A sensor platform for use in sample analysis comprises a substrate (30) of refractive index (n1) and a thin, optically transparent layer (32) of refractive index (n2) on the substrate, (n2) is greater than (n1). The platform incorporates one or multiple corrugated structures in the form of periodic grooves (31), (33), which defines one or more sensing areas each for one or more capture elements. The grooves are so profiled, dimensioned and oriented that when coherent light is incident on the platform it is diffracted into individual beams or diffraction order resulting in reduction of the transmitted beam and an abnormal high reflection of the incident light thereby creates an enhanced evanescent field at the surface of the or each sensing area. The amplitude of this field at the resonant condition is greater by an order of approximately 100 than the field of prior art platforms so that the luminescence intensity created from samples on the platform is also increased by a factor of 100. Also disclosed are an apparatus incorporating the platform and a method of using the platform. Further increases of amplitude have been detected by using light having a linear component which gives rise to TM excitation and/or irradiating the platform from the substrate side.

This invention relates generally to the field of analysing samples and has particular, but not exclusive, application in the field of affinity sensing for example that known generally as DNA, protein, peptide and antibody chip technology. One aspect of the invention is concerned with a sensor platform which can be used to analyse samples. Another aspect of the invention is concerned with an apparatus which makes use of the sensor platform. A further aspect of the invention is concerned with the process for analysing samples which makes use of the platform.
Techniques for analysing two-dimensional arrays of samples are known. One such technique is known as an ELISA assay and is based upon the intense biochemical reaction between antibodies and antigens. Special mono or polyclonal antibodies are immobilised on substrates and react with complimentary species. Fluorophore labelled markers are added, activated via enzyme-linked antibodies, and the samples are irradiated with light in order to induce fluorescence. The fluorescence is detected and the intensity of the fluorescence is indicative of the affinity reaction.
Another known technique is that described in W098/27430. In this a large number of different species are immobilised in an array on a substrate. The species are immobilised on the substrate by photolithographical means. Fluorophore labelled markers are added to the species. A sample is prepared and reacted with the immobilised species and the whole chip is scanned with a focused laser beam. Alternatively a sample is prepared and modified with fluorophore labelled markers and reacted with the immobilised species and the whole chip is scanned with a focussed laser beam. The fluorescent signals are detected by photodetectors and a 2D pattern is produced. Changes in this pattern between individual samples provide an indication of differences in gene expression and therefore provides information about pharmacology and toxicology.
Another known technique is that based on evanescent wave sensors. These make use of coherent laser light which is trapped in a very thin layer and creates so-called evanescent electromagnetic fields which extends for a small distance outside the actual physical sensor. This field can interact with molecules attached to the surface of the sensor. This evanescent excitation or interaction is limited to a region very close to the vicinity of the waveguide, typically 0.5 microns for visible light from the surface. The evanescent fields remain localised spatially and do not transfer their stored energy to other regions. The interaction of the laser light with the molecules can be used in a number of different ways. These include:
1 Detection of luminescence induced by the evanescent field.
2 Detection of changes in refractive index which occur when molecules of a sample bind to capture molecules.
3 Detection of surface plasmon resonance.
One particular sensor which uses an evanescent field is known as a planar waveguide sensor. The planar waveguide sensor comprises a planar substrate having formed thereon a thin wave guiding layer. Part of the wave guiding layer incorporates a grating onto which laser light is incident and from which the laser light is launched so that it propagates through the waveguide layer to a sensing region remote from the grating. The waveguide sensor can be either used in a mass sensitive mode (cf. 2, 3 above), or with superior sensitivity in combination with luminescence excitation and detection (cf. 1 above). Capture molecules are immobilised on the sensing area and the analyte (sample) is then brought into contact with the sensing area/capture molecules in the presence of added labelled molecules with similar affinity (competition). Alternatively, analyte molecules may bind to immobilised capture molecules and fluorescence labels are introduced by reaction of a further labelled species with the captured analyte molecules. Laser light launched into the waveguiding layer leads to evanescent excitation of the fluorophores which then allows the quantification of the analyte. The emitted fluorescence is detected and the intensity of the fluorescence provides an indication of the interaction that has occurred between affinity partners present in the analyte and the immobilised capture molecules. It should be noted that in this type of arrangement the laser radiation propagates inside the waveguide over relatively long distances and the coupling grating and the sensing areas are geometrically separated. (See WO 95/33197 and WO 95/33198).
EP-0 455 067 A2 describes a planar waveguide sensor exploiting the detecting principle of refractive index changes. The platform shallow grooves formed over the entire platform couple polarised, coherent light into the transparent waveguiding layer where it is coupled out after some distance. The angle of the outcoupled beam changes when analyte molecules bind to capture molecules.
Another example of the refractive index type is given in U.S. Pat. No. 5,738,825. The platform contains individual gratings being in contact with the wells of a microtiter plate.
EP 178 083 discloses Surface Plasmon Resonance (SPR) in which the energy of incoming photons is converted to electrical energy as a surface plasmon wave. The sensor architecture requires a metal layer in contrast to the platform of the present invention, and the amount of reflected light at the critical angle is, or approximates to, zero in contrast with the present invention in which the reflected intensity reaches almost 100%.
All the above techniques suffer from various disadvantages. Some are very slow because each sample has to be excited individually. Others such as the planar waveguide allow excitation of more than one sample at a time, but do not provide entirely reliable results because of fluorescence crosstalk between different capture elements and locally varying excitation light intensities due to losses of the waveguides and local variations of coupled power due to variations of grating coupling efficiencies.
The present invention is concerned with a technique which allows multiple samples to be analysed simultaneously in an extremely sensitive, reliable, and quantitative manner.
In contrast to planar waveguide sensors, the present invention shows no luminescence crosstalk and local light intensities are well defined. The present invention allows true multiplexing, i.e. the transducer requires no stacked substructure (as is the case for planar waveguides) and can be seen as a universal platform, where, depending on the requirements, size and number of recognition elements can be varied within the technical feasible limitations, without requiring changes in the chip structure (corrugated areas and sensing areas are not separated as is the case for planar waveguides). In addition, the invention delivers about 100 fold stronger luminescence intensities compared to prior epifluorescence techniques. The experimental set-up is very simple and requires solely a simple adjustment of the angle of the incident light beams The transducers described in the present invention, can be easily adapted to conventional fluorescence microscopes, confocal microscopes, and laser scanners. Furthermore, for transducers with a broad resonance width (defined as Full Width at Half Maximum, FWHM) and a resonance position at or close to normal incidence, angle adjustments are obsolete.
The production process of the platform is relatively simple (cheap) and the performance of existing systems (i.e. fluorescence scanners, microscopes, fluorescence microtiter plate readers, . . . ) can be easily increased by modest modifications of the respective set-ups.
According to a first aspect of the present invention there is provided a platform for use in sample analysis comprising an optically transparent substrate having a refractive index (n1), a thin, optically transparent layer, formed on one surface of the substrate, said layer having a refractive index (n2) which is greater than (n1), said platform incorporating therein one or multiple corrugated structures comprising periodic grooves which define one or multiple sensing areas or regions, each for one or multiple capture elements, said grooves being so profiled, dimensioned and oriented that either
a) coherent light incident on said platform is diffracted into individual beams or diffraction orders which interfere resulting in reduction of the transmitted beam and an abnormal high reflection of the incident light thereby generating an enhanced evanescent field at the surface of the one or multiple sensing areas; or
b) coherent and linearly polarised light incident on said platform is diffracted into individual beams or diffraction orders which interfere resulting in almost total extinction of the transmitted beam and an abnormal high reflection of the incident light thereby generating an enhanced evanescent field at the surface of the one or multiple sensing areas.
According to a second aspect of the present invention there is provided a platform comprising an optically transparent substrate having a refractive index (n1), a thin, optically transparent layer, formed on one surface of the substrate, said layer having a refractive index (n2) which is greater than (n1), said platform incorporating in the transparent layer a corrugated structure substantially over the entire platform, or multiple separate corrugated structures arranged on the platform, said structures comprising substantially parallel periodic grooves which are mono- or multi-diffractional which grooves represent one or multiple sensing areas or regions, wherein
(a) the depth of the grooves is in the range of 3 nm to the thickness of the optically transparent layer,
(b) the thickness of the optically transparent layer is in the range of 30 to 1000 nm,
(c) the period of the corrugated structure is in the range of 200 to 1000 nm,
(d) the ratio of groove depth to the thickness of the optically transparent layer is in the range of 0.02 to 1, and
(e) the ratio of groove width to the period of the grooves is in the range of 0.2 to 0.8. The arrangement may be such that, in use, the grooves are so profiled, dimensioned and oriented that either
a) coherent light incident on the platform is diffracted into individual beams or diffraction orders which interfere resulting in reduction of the transmitted beam and an abnormal high reflection of the incident light thereby generating an enhanced evanescent field at the surface of the one or multiple sensing areas; or
b) coherent and linearly polarised light incident on said platform is diffracted into individual beams or diffraction orders which interfere resulting in almost total extinction of the transmitted beam and an abnormal high reflection of the incident light thereby generating an enhanced evanescent field at the surface of the one or multiple sensing areas.
As used herein, orientation is understood to mean that the electric field vector of the linearly polarised light is parallel or perpendicular to the grooves. As used herein, coherent light is understood to mean that the coherence length of the radiation, i.e. the spatial extent to which the incident beam has a defined phase relation, is large compared to the thickness of the platform.
The evanescent field decays exponentially within wavelength dimensions of the incident beam (less than 1 xcexcm).
An important aspect of the present invention is the use of a platform in which so-called evanescent resonance can be created. Abnormal reflection is a phenomenon which has been described theoretically in the prior art for example in a paper entitled xe2x80x9cTheory and applications of guided mode resonance filtersxe2x80x9d by S S Wang and R Magnusson in Applied Optics, Vol. 32, No 14, May 10, 1993, pages 2606 to 2613 and in a paper entitled xe2x80x9cCoupling gratings as waveguide functional elementsxe2x80x9d by O. Parriaux et al, Pure and Applied Optics 5, (1996) pages 453-469. As explained in these papers resonance phenomena can occur in planar dielectric layer diffraction gratings where almost 100% switching of optical energy between reflected and transmitted waves occurs when the grooves of the diffraction grating have sufficient depth and the radiation incident on the corrugated structure is at a particular angle. In the present invention this phenomenon is exploited in the sensing area of the platform where that sensing area includes diffraction grooves of sufficient depth and light is caused to be incident on the sensing area of the platform at an angle such that evanescent resonance occurs in that sensing region. This creates in the sensing region an enhanced evanescent field which is used to excite samples under investigation. It should be noted that the 100% switching referred to above occurs with parallel beam and linearly polarised coherent light and the effect of an enhanced evanescent field can also be achieved with non-polarised light of a non-parallel focussed laser beam.
At resonance conditions the individual beams interfere in such a way that the transmitted beam is cancelled out (destructive interference) and the reflected beam interferes constructively giving rise to abnormal high reflection.
By choosing appropriate parameters for the above mentioned corrugated layer structure the excitation energy remains highly localized. Such structures are described in the literature as photonic band gap structures, materials with periodic spatial variations of their refractive index such that electromagnetic radiation cannot propagate in any direction. Photonic bandgap structures allow highly localized modes to appear, see e.g. the paper entitled xe2x80x9cLocalisation of One Photon Statesxe2x80x9d by C. Adlard, E. R. Pike and S. Sarkar in Physical Review Letters, Vol. 79, No 9, pages 1585-87 (1997). Such structures exhibit extremely large propagation losses corresponding to a mode localisation in the xcexcm regime.
The platform of the present invention can be considered as optically active in contrast to optically passive platforms constructed from e.g. a glass or polymer. Here, optically active means increasing the electromagnetic field of the excitation beam by energy confinement.
The substrate of the platform may be formed from inorganic materials such as glass, SiO2, quartz, Si. Alternatively the substrate can be formed from organic materials such as polymers preferably polycarbonate (PC), poly(methyl methacrylate) (PMMA), polyimide (PI), polystyrene (PS), polyethylene (PE), polyethylene terephthalate (PET) or polyurethane (PU). These organic materials are especially preferred for point-of-care (POC) and personalized medical applications since glass is not accepted in such an environment. Plastics substrates can be structured (embossed) much more easily than glass. In one example the substrate is formed from glass.
The optically transparent layer may be formed from inorganic material. Alternatively it can be formed from organic material. In one example the optically transparent layer is a metal oxide such as Ta2O5, TiO2, Nb2O5, ZrO2, ZnO or HfO2. The optically transparent layer is non-metallic.
Alternatively the optically transparent layer can be made of organic material such as polyamide, polyimide, polypropylene (PP), PS, PMMA, polyacryl acids, polyacryl ethers, polythioether, poly(phenylenesulfide), and derivatives thereof (see for example S S. Hardecker et al., J. of Polymer Science B: Polymer Physics, Vol. 31, 1951-63, 1993).
The depth of the diffraction grooves may be in the range 3 nm to the thickness of the optically transparent layer and preferably 10 nm to the thickness of the optically transparent layer e.g. 30 nm to the thickness of the optically transparent layer. The thickness of the optically transparent layer be in the range 30 to 1000 nm, e.g. 50 to 300 nm, preferably 50-200 nm, the period of the corrugated structure may be in the range 200 to 1000 nm, e.g. 200 to 500 nm, preferably 250-500 nm, the ratio of the groove depth to the thickness of the optically transparent layer may lie in the range 0.02 to 1 e.g. 0.25 to 1, preferably 0.3 to 0.7, and the ratio of the grooves width to the period of the grooves (xe2x80x9cduty-cyclexe2x80x9d) may lie in the range 0.2 to 0.8, e.g. 0.4 to 0.6.
The grooves may be generally rectangular in cross-section. Alternatively, the grooves may be sinusoidal or of saw tooth cross-section. The surface structure may be generally symmetrical. Preferred geometries include rectangular, sinusoidal, and trapezoidal cross-sections. Alternatively, the grooves may be of saw tooth cross-section (blazed grating) or of other asymmetrical geometry. In another aspect the groove depth may vary, e.g. in periodic modulations.
The platform may be square or rectangular and the grooves may extend linearly along the platform so as to cover the surface. Alternatively the platform may be disc shaped and the grooves may be circular or linear.
The grooves may be formed on a surface of the substrate. Alternatively the grooves may be formed on a surface of the optically transparent layer. As a further alternative, grooves may be formed both on the surface of the substrate which is the interface and on the surface of the optically transparent layer.
The corrugated surface of a single sensing area may be optimized for one particular excitation wavelength and for one particular type of polarisation. By appropriate means, e.g. superposition of several periodic structures which are parallel or perpendicular one with another, periodic surface reliefs can be obtained that are suitable for multiple wavelength use of the platform (xe2x80x9cmulticolourxe2x80x9d applications). Alternatively, individual sensing areas on one platform may be optimized for different wavelengths and/or polarization orientations.
The surface of the optically transparent layer may include one or a plurality of corrugated sensing areas which each may carry one or a plurality of capture elements.
Each capture element may contain individual and/or mixtures of capture molecules which are capable of affinity reactions. The shape of an individual capture element may be rectangular, circular, ellipsoidal, or any other shape. The area of an individual capture element is between 1 xcexcm2 and 10 mm2, e.g. between 20 xcexcm2 and 1 mm2 and preferably between 100 xcexcm2 and 1 mm2. The capture elements may be arranged in a regular two dimensional array. The center-to-center (ctc) distance of the capture elements may be between 1 xcexcm and 1 mm, e.g. 5 xcexcm to 1 mm, preferably 10 xcexcm to 1 mm.
The number of capture elements per sensing area is between 1 and 1,000,000, preferably 1 and 100,000. In another aspect, the number of capture elements to be immobilized on the platform may not be limited and may correspond to e.g. the number of genes, DNA sequences, DNA motifs, DNA micro satelites, single nucleotide polymorphisms (SNPs), proteins or cell fragments constituting a genome of a species or organism of interest, or a selection or combination thereof. In a further aspect, the platform of this invention may contain the genomes of two or more species, e.g. mouse and rat.
The platform may include an adhesion promoting layer disposed at the surface of the optically transparent layer in order to enable immobilisation of capture molecules. The adhesion promoting layer may also comprise a microporous layer (ceramics, glass, Si) for further increasing assay and detection efficacy or of gel layers which either can be used as medium for carrying out the capture element immobilisation and sample analysis, thereby further increasing the assay and detection efficacy, or which allow separation of analyte mixtures in the sense of gel electrophoresis. The platform may be formed with a plurality of sensing areas or regions, each having its own diffractive grooves.
A feature of the platform of this invention is that light energy entering the optically transparent layer is diffracted out of the layer immediately due to the nature of the corrugated platform. Therefore no or negligible waveguiding occurs. Typically the propagation distance is 100 xcexcm or less, preferably 10 xcexcm or less. This is a very surprisingly short distance. The propagation distance is the distance over which the energy of the radiation is reduced to 1/e.
A third aspect of the invention provides apparatus for analysing samples comprising a platform according to said first or second aspect, means for generating a light beam and for directing the beam so that it is incident upon the platform at an angle which causes evanescent resonance to occur in the platform to thereby create an enhanced evanescent field in the sensing area of the platform, and means for detecting a characteristic of a material disposed on the sensing area of the platform. The range of angles suitable for creating a resonance condition is limited by the angle of total reflection for incident light on the platform. Preferred angles are less than 45xc2x0, e.g. 30xc2x0 or less, e.g. 20xc2x0 to 10xc2x0 or below, e.g. 0.1xc2x0 to 9.9xc2x0. The angle may equal or approximate normal incidence. The light generating means may comprise a laser for emitting a coherent laser beam. Other suitable light sources include discharge lamps or low pressure lamps, e.g. Hg or Xe, where the emitted spectral lines have sufficient coherence length, and light-emitting diodes (LED). The apparatus may also include optical elements for directing the laser beam so that it is incident on the platform at an angle xcex8, and elements for shaping the plane of polarisation of the coherent beam, e.g. adapted to transmit linearly-polarised light. The angle xcex8 may be defined by the expression sin xcex8=nxe2x88x92xcex/xcex9 where xcex9 is a period of the diffractive grooves, xcex is the wavelength of the incident light and n is the effective refractive index of the optically transparent layer.
Examples of lasers that may be used are gas lasers, solid state lasers, dye lasers, semiconductor lasers. If necessary, the emission wavelength can be doubled by means of non-linear optical elements. Especially suitable lasers are argon ion lasers, krypton ion lasers, argon/krypton ion lasers, and helium/neon lasers which emit at wavelengths between 275 and 753 nm. Very suitable are diode lasers or frequency doubled diode lasers of semiconductor material which have small dimensions and low power consumption.
Another appropriate type of excitation makes use of VCSEL""s (vertical cavity surface-emitting lasers) which may individually excite the recognition elements on the platform.
The detecting means may be arranged to detect luminescence such as fluorescence. Affinity partners can be labelled in such a way that Fxc3x6rster fluorescence energy transfer (FRET) can occur upon binding of analyte molecules to capture molecules. The maximum of the luminescence intensity might be slightly shifted relative to the position of highest abnormal reflection depending on the refractive index values of the layer system and the corresponding Fresnel Coefficients.
The samples may be used either undiluted or with added solvents. Suitable solvents include water, aqueous buffer solutions, protein solutions, natural or artificial oligomer or polymer solutions, and organic solvents. Suitable organic solvents include alcohols, ketones, esters, aliphatic hydrocarbons, aldehydes, acetonitrile or nitrites.
Solubilisers or additives may be included, and may be organic or inorganic compounds or biochemical reagents such as diethylpyrocarbonate, phenol, formamide, SSC (sodium citrate/sodium chloride), SDS (Sodiumdodecylsulfate), buffer reagents, enzymes, reverse transcriptase, RNAase, organic or inorganic polymers.
The sample may also comprise constituents that are not soluble in the solvents used, such as pigment particles, dispersants and natural and synthetic oligomers or polymers.
The luminescence dyes used as markers may be chemically or physically, for instance electrostatically, bonded to one or multiple affinity binding partners (or derivatives thereof) present in the analyte solution and/or attached to the platform. In case of naturally-occurring oligomers or polymers such as DNA, RNA, saccharides, proteins, or peptides, as well as synthetic oligomers or polymers, involved in the affinity reaction, intercalating dyes are also suitable. Luminophores may be attached to affinity partners present in the analyte solution via biological interaction such as biotin/avidin binding or metal complex formation such as HIS-tag coupling.
One or multiple luminescence markers may be attached to affinity partners present in the analyte solution, to capture elements immobilized on the platform, or both to affinity partners present in analyte solution and capture elements immobilized at the platform, in order to quantitatively determine the presence of one or multiple affinity binding partners.
The spectroscopic properties of the luminescence markers may be chosen to match the conditions for Fxc3x6rster Energy Transfer or Photoinduced Electron Transfer. Distance and concentration dependent luminescence of acceptors and donors may then be used for the quantification of analyte molecules.
Quantification of affinity binding partners may be based on intermolecular and/or intramolecular interaction between such donors and acceptors bound to molecules involved in affinity reactions. Intramolecular assemblies of luminescence donors and acceptors covalently linked to affinity binding partners, Molecular Beacons (S. Tyagi et al., Nature Biotechnology 1996, 14, 303-308) which change the distance between donor and acceptor upon affinity reaction, may also be used as capture molecules or additives for the analyte solution. In addition, pH and potentially sensitive luminophores or luminophores sensitive to enzyme activity may be used, such as enzyme mediated formation of fluorescing derivatives.
Transfluorospheres or derivatives thereof may be used for fluorescence labelling, and chemi-luminescent or electro-luminescent molecules may be used as markers.
Luminescent compounds having luminescence in the range of from 400 nm to 1200 nm which are functionalised or modified in order to be attached to one or more of the affinity partners, such as derivatives of
polyphenyl and heteroaromatic compounds
stilbenes,
coumarines,
xanthene dyes,
methine dyes,
oxazine dyes,
rhodamines,
fluoresceines,
coumarines, stilbenes,
pyrenes, perylenes,
cyanines, oxacyanines, phthalocyanines, porphyrines, naphthalopcyanines, azobenzene derivatives, distyryl biphenyls,
transition metal complexes e.g. polypyridyl/ruthenium complexes, tris(2,2xe2x80x2-bipyridyl)ruthenium chloride, tris(1,10-phenanthroline)ruthenium chloride, tris(4,7-diphenyl-1,10-phenanthroline) ruthenium chloride and polypyridyl/phenazine/ruthenium complexes, such as octaethyl-platinum-porphyrin, Europium and Terbium complexes may be used as luminescence markers.
Suitable for analysis of blood or serum are dyes having absorption and emission wavelength in the range from 400 nm to 1000 nm. Furthermore luminophores suitable for two and three photon excitation can be used.
Dyes which are suitable in this invention may contain functional groups for covalent bonding, e.g. fluorescein derivatives such as fluorescein isothiocyanate. Also suitable are the functional fluorescent dyes commercially available from Amersham Life Science, Inc. Texas. and Molecular Probes Inc.
Other suitable dyes include dyes modified with deoxynucleotide triphosphate (dNTP) which can be enzymatically incorporated into RNA or DNA strands. Further suitable dyes include Quantum Dot Particles or Beads (Quantum Dot Cooperation, Palo Alto, Calif.) or derivatives thereof or derivatives of transition metal complexes which may be excited at one and the same defined wavelength, and derivatives show luminescence emission at distinguishable wavelengths.
Analytes may be detected either via directly bonded luminescence markers, or indirectly by competition with added luminescence marked species, or by concentration-, distance-, pH-, potential- or redox potential-dependent interaction of luminescence donors and luminescence/electron acceptors used as markers bonded to one and/or multiple analyte species and/or capture elements. The luminescence of the donor and/or the luminescence of the quencher can be measured for the quantification of the analytes.
In the same manner affinity partners can be labelled in such a way that electron transfer or photoinduced electron transfer leads to quenching of fluorescence upon binding of analyte molecules to capture molecules.
Appropriate detectors for luminescence include CCD-cameras, photomultiplier tubes, avalache photodiodes, photodiodes, hybrid photomultiplier tubes.
The detection means can be arranged to detect in addition changes in refractive index.
The incident beam may be arranged to illuminate the sensing area or all sensing areas on one common platform. Alternatively the beam can be arranged to illuminate only a small sub-area of the sensing area to be analysed and the beam and/or the platform may be arranged so that they can undergo relative movement in order to scan the sensing area of the platform.
Accordingly the detecting means may be arranged in an appropriate way to acquire the luminescence signal intensities of the entire sensing area in a single exposure step. Alternatively the detection and/or excitation means may be arranged in order to scan the sensing areas stepwise.
The apparatus may include a cartridge for location against the sensing area of the platform to bring a sample into contact with the sensing area. The cartridge may contain further means in order to carry out sample preparation, diluting, concentrating, mixing, bio/chemical reactions, separations, in a miniaturised format (see WO 97/02357). The apparatus may include a microtiter type device for containing a plurality of samples to be investigated.
A fourth aspect of the present invention provides a process for analysing a sample or samples which comprises bringing the sample into contact with the sensing area of a platform according to said first or second aspect, irradiating the platform with a light beam such that evanescent resonance is caused to occur within the sensing area of the platform and detecting radiation emanating from the sensing area. The method may comprise adding fluorescent inducing material to the samples under investigation and sensing fluorescence induced in said samples by excitation of the samples by the enhanced evanescent field. Alternatively the method may comprise adding fluorescence inducing or quenching material to the samples under investigation and/or transfer of the samples under investigation into fluorescing or quenching derivatives and sensing fluorescence induced by said samples bound at the sensing platform by excitation with the enhanced evanescent field.
It is believed to be a novel and inventive concept to provide a sensor platform in which each sensing area or region has attached thereto more than one type of capture element or molecule. This concept applies whether the platform is designed for evanescent resonant mode or a more conventional mode such as waveguiding. Thus, according to another aspect of the present invention there is provided a platform for use in a sample analysis, said platform having one or more sensing areas or regions, each for receiving a capture element or elements which when the platform is irradiated with coherent light can interact to provide an indication of an affinity reaction, wherein each capture element includes two or more types of capture molecule.
The above-described embodiments of this invention contemplate light polarised parallel with the longitudinal axis of the grooves of the platform, giving rise to xe2x80x9cTExe2x80x9d excitation, or light polarised perpendicular to the longitudinal axis of the grooves of the platform, giving rise to xe2x80x9cTMxe2x80x9d excitation. Further, light may be incident either onto the corrugated, optically transparent, high refractive index layer side of the platform (xe2x80x9cchipxe2x80x9d) or onto the other side of the platform, i.e. onto the optically transparent substrate side.
The nature of polarisation and aspects of excitation of TE and TM modes are discussed in Guided Wave Optoelectronics, Ed. T. Tamir, 1988, Springer Verlag, specifically the Chapter entitled Theory of Optical Waveguides, Author: H. Kogelnik, the contents of which are incorporated herein by reference.
The present applicants have found that even greater amplification can be obtained by exploiting the abnormal reflection geometry provided by TM excitation compared to TE excitation.
A further increase in sensitivity may be obtained when the light incident on the platform is directed onto the optically transparent substrate. This may be attractive for e.g. fluorescence laser scanners.
In a further aspect, therefore, this invention provides a platform, apparatus or detection method as described herein adapted to TM excitation.
It will be appreciated that varying degrees of polarisation of the incident light beam may be employed, depending e.g. on field of application and resources available or required. The abnormal reflection and/or fluorescence enhancement described herein is observed preferably from the linearly polarised component of the incident light. Thus the light incident on the platform may be e.g. substantially linearly polarised or circularly or elliptically polarised.
Increases of signal intensity amplification have been detected by a factor of up to around 5 to 10 using TM excitation over TE excitation.
In a further aspect, this invention provides a platform, apparatus or detection method as described herein wherein the light beam is irradiated onto the transparent substrate side of the platform. The applicants have found that several times greater signal intensity, e.g. a factor of 5 to 7, may be obtained when irradiating the platform onto the substrate side instead of onto the corrugated, optically transparent, high refractive index layer side of the platform.
An increase in signal intensity amplification by a factor of around 50 may be obtained by employing TM excitation with the light beam incident onto the substrate side compared with TE excitation and the light beam incident onto the corrugated, optically transparent, high refractive index layer side of the platform.

Sensor platform, apparatus incorporating the platform, and process using the platform


A connecting adjustment assembly for a fall protection assembly including a back plate assembly and a sliding engagement member is provided. The back plate assembly includes a body and a roller. The body has a first side and an opposed second side. The body further has a first edge and an opposed second edge that defines the length of the body. The body also has a third edge and an opposed fourth edge that defines a width of the body. The body still further has a groove in the second side that passes along the width of the body. The roller is rotationally coupled proximate the second edge of the body. The sliding engagement member includes a first portion with a first post and a second portion with a connection head. The first post is configured and arranged to be at least partially received within the groove of the body.

Fall protection assemblies that include climbing straps are often used by utility workers when climbing up utility poles. The climbing straps can include a first strap that is placed around an outer portion of the pole to be climbed and an inner strap that is positioned around an inner portion of the pole to be climbed. If a fall event occurs, the straps cinch up on the pole to limit the distance of the fall. The straps are connected together via connecting members. The ability to loosen and tighten the straps around the pole to position the straps as the worker climbs or descends the pole is an important function for a fall protection assembly. The connectors should aid in the loosening and tightening functions of the straps.
For the reasons stated above and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for connecting members that provide effective and efficient means for connecting straps and loosening and tightening straps.


An inkjet recording apparatus includes memory, a processor, an image forming section, and a bending mechanism. The memory stores therein bending information in which a plurality of bending amounts corresponding to respective ejection amounts of an ink ejected from the image forming section are defined. The processor sets a bending amount of a sheet to be conveyed. The bending mechanism includes a roller and a belt that hold the sheet therebetween, and bends the sheet by moving a position of a center of the roller toward the belt based on the set bending amount. The processor calculates for each of areas of the sheet an amount of the ink ejected to the area, and sets the bending amount of the sheet based on the bending amounts corresponding to the calculated amounts of the ink ejected to the respective areas in the bending information.

An inkjet recording apparatus disclosed in Patent Literature 1 prints on a first side of a sheet. After printing on the first side, it is determined whether or not conveyance of the sheet must stop based on image data of an image which has been printed on the first side. When conveyance must be stopped after printing on the first side, a stopping time is determined based on the image data, and the conveyance of the sheet is stopped so that the sheet is put in standby. The reasoning for putting the sheet in standby is to dry ink adhered to the sheet and decrease curling in the sheet. After the determined stopping time has passed, the inkjet recording apparatus prints on a second side of the sheet.


A wellhead assembly includes first and second wellhead members. An annular lock groove is located on an inner or an outer diameter surface of the first wellhead member. An annular lock ring is supported on an annular shoulder of the second wellhead member and is radially moveable between an unset position and a set position where a locking profile of the annular lock ring engages the annular lock groove. The second wellhead member is positioned concentrically with the first wellhead member, defining an annulus between the first and second wellhead members. An energizing ring is positioned in the annulus and axially movable between an unengaged position and an engaged position. The energizing ring has an engaging portion with a corrugated shape in cross section that is interference fit between the annular lock ring and the second wellhead member when the energizing ring is in the engaged position.

1. Field of Disclosure
This invention relates in general to wellhead assemblies, and in particular to energizing rings used to lock down concentric tubular members.
2. Description of Related Art
Wellhead assemblies can include concentric tubular shaped members. Outer and inner wellhead members can be, for example, a wellhead housing, casing hanger, tubing hanger, seal assembly, or other member with a generally ring shaped cross section. Throughout the life of the wellhead assembly, forces within the wellhead assembly can push the inner wellhead member axially up and down. As an example, when the wellhead members are subjected to high pressures, the high pressures can cause the inner wellhead member to move axially upward relative to the outer wellhead member. Thermal expansion can also lead to relative axial movement between outer and inner wellhead members.
Small relative axial movement can also occur between the inner wellhead member and the outer wellhead member due to stack up tolerances. This motion can cause wear of the adjacent surfaces, jeopardizing the integrity of the inner wellhead member and the outer wellhead member. Relative movement between components is, for example, of particular concern for metal to metal seal elements. In cases where small relative axial movement is undesirable, a preload force can be generated through the load path between lockdown ring flanks and mating faces of an annular recess within the entire stack up tolerance range, to reduce or eliminate any relative axial movement between the inner wellhead member and the outer wellhead member.
A lockdown ring can be used to prevent or reduce relative axial movement between outer and inner wellhead members. Lockdown rings can be energized by an energizing ring. Once the energizing ring energizes the lockdown ring, the energizing ring stays in place to maintain the radial position of the lockdown ring. In some current wellhead systems, continued pressure and force from the lockdown ring on the energizing ring, can be sufficient to move the lockdown ring from the set position to an unset position. In addition, due to the stack up tolerances, the lock ring may not land in a predicable location and may not provide sufficient locking forces to prevent relative movement between outer and inner wellhead members.
In some current energizing rings, the engaging surfaces of the energizing ring are straight. Such energizing rings can only displace the lock ring a set radial amount. Therefore depending on the stack up tolerances, such energizing rings can allow for more than acceptable amounts of relative axial movement between the inner wellhead member and the outer wellhead member.
In other current energizing rings, a taper can be incorporated into the energizing ring. A tapered energizing ring interface ensures contact of the lock ring flanks throughout the stack up tolerance range but requires an additional lock down device for the energizing ring, which can require a separate tool and additional trips into the well to operate. In addition there is not positive stop for the energizing ring so the exact set position of the energizing ring will be unknown.

Corrugated energizing ring for use with a split lockdown ring


Adjacent tissue layers can be accessed using a catheter device with a distal tip having a conductive portion including a first cutting feature and one or more projections extending from the first cutting feature towards an outer diameter of the distal tip. Electrical energy can be supplied to the conductive portion of the device to cut tissue. A stent can be delivered to form a fluid communication between the adjacent tissue layers.

A number of inter and intra-luminal endoscopic procedures require precise placement of anchors or stents. For example, a number of procedures may be performed by entering the gastrointestinal (GI) tract through a first organ or structure, such as the esophagus, stomach, duodenum, small intestine, or large intestine, and delivering the anchor or stent to adjacent organs and lumen or tissue structures such as an adjacent portion of the GI tract, the bile duct, the pancreatic duct, the gallbladder, the pancreas, cysts, pseudocysts, abscesses, and the like. While primarily intended for use in the GI tract, such methods and apparatus can also be used for access to and from portions of the urinary tract, such as the urinary bladder and ureter, the pulmonary tract, such as the trachea and bronchi, and the biliary tract, such as the bile duct and gallbladder, as well.
Intra-ductal stents are commonly used to facilitate the opening of closed vessels for access, drainage or other purposes. Tissue anchors are used to secure adjacent tissues or organs. Inter-luminal tissue anchors, which include a central lumen, are used to facilitate fluid communication between adjacent ducts, organs or lumens. Often, the precise placement of the tissue anchor or stent is necessary, especially when the tissue anchor or stent has well defined anchoring elements at the proximal and/or distal ends, and the device is used to secure adjacent lumens.
When deploying a stent or other tissue anchor between adjacent body lumens, organs, or other structures, it is typically necessary to penetrate both a wall of the first body lumen through which access is established and a wall of a second body lumen which is the target for the procedure. When initially forming such access penetrations, there is a significant risk of leakage from either or both of the access body lumen and the target body lumen into the surrounding space including, but not limited to the peritoneal cavity. In some procedures, such as those involving transgastric or transduodenal bile duct access, loss of body fluid into surrounding tissues and body cavities can present a substantial risk to the patient. The risk can be exacerbated when it is necessary to not only penetrate the luminal walls to gain initial access, usually with a needle, but to subsequently enlarge or dilate the initial penetration, for example by passing a tapered dilator over the needle used to establish initial access. Dilation of the initial tissue penetration can cause additional damage to the tissue penetration and is an additional opportunity for leakage.
Thus, it would be desirable to establish initial luminal wall penetrations and to subsequently dilate said penetrations in order to deploy a stent, anchor, or for other purposes, while minimizing the risk of body fluid leakage. It is also desirable for improved access to body lumens while minimizing trauma and damage to the tissue surrounding the initial luminal wall penetration. It would be further desirable to provide improved protocols and access tools which are capable of being deployed from endoscopes present in a first body lumen to access adjacent body lumens or cavities while minimizing the risk of leakage. Such access tools and protocols should be compatible with a wide variety of procedures, such as placement of stents or other tissue anchors between adjacent luminal walls, and will preferably reduce or eliminate the need to exchange tools during the access procedure.

Methods and devices for access across adjacent tissue layers


A non-extrusion device for split annular well casing and tubing hanger compression seals has a flat annular body having truncated, radially-split cone portions forming through holes for receiving pins or bolts and for guiding a compressed elastomer seal between inner and outer tubing structures along a radial direction to prevent axial extrusion of the seal.

This invention relates to well casing support systems for suspending oilwell casings from a surface wellhead, and more particularly to split annular compression seals for use with a slip hanger forming a seal between a well casing and an inner surface of a casing head.
Prior known compression seals form a seal when an annular elastomer seal is compressed within the slip hanger structure. This type of seal is typically compressed between two or more relatively displaceable annular slip hanger components. The seal is typically formed with through holes for receiving pins or bolts that guide or draw together the slip hanger components. When the slip hanger components are displaced toward each other axially, the annular compression seal is deformed along a radial plane to engage the casing and the inner surface of the casing head.
Problems have occurred with these types of seals under broad temperature ranges because of the difficulty in controlling elastomer extrusion through the gaps that are necessary due to the manufacturing tolerances of the casing wellhead and hanger components. Furthermore, the thermal expansion and contraction of elastomer seal elements encased in the steel elements of hangers increase the difficulty in sealing due to amplification of stress in the elastomer. This results because the coefficient of thermal expansion of elastomers is about ten times greater than steel. With continuing development of the petroleum industry in increasingly severe environments, the requirements for safely controlling downhole pressures communicated to the surface of oilwells continue to become more demanding. Problems have occurred in these types of seals when the seals are extruded so that the diameters of through holes for receiving pins or bolts have a greater diameter than that of the pins or bolts, causing gaps in the seal. Similarly, gaps occur at inner and outer contact surfaces and at splits in between components adjacent the seal element.
Prior attempts to solve this problem included molding fabric or cord into the elastomer seal. This method has proven to have very limited capability at higher elastomer pressures. Another prior attempt to solve this problem, illustrated in FIG.5, has included the use of low modulus material and split extrusion washers 22 placed in a conical countersink 23 beneath a non-extrusion plate 21 adjacent the pins or bolts 12' as shown in FIG. 5. This method creates the need for many additional parts, especially if many load bolts or pins are required to pass through the seal element. Such a solution adds to cost and increased probability of assembly errors.

Non-extrusion device for split annular casing/tubing hanger compression seals


Carbon black is produced from a pyrolyzed hydrocarbon wherein pyrolysis is effected by combusting a synthesis gas containing hydrogen and carbon monoxide. The synthesis gas is produced from reforming a hydrocarbon fuel, wherein the reformation is heated by combusting carbon black effluent tail gas or indirect heat exchange of the hot tail gas.

In the manufacture of carbon black, natural gas is combusted with a stoichiometric excess of oxidant, typically air, to provide a hot combustion gas. Oil feedstock is sprayed into the hot gas causing it to pyrolyze into elemental carbon product. This product is carried in the reactor tail gas through various quench steps and heat recovery before it is separated in a filter device. Residual, low pressure tail gas from the filters contains large quantities of nitrogen, water, carbon dioxide, hydrogen and carbon monoxide yielding a low BTU(50-150 British Thermal Unit/standard cubic foot BTU/SCF) fuel. Some tail gas is used to fuel carbon dryer furnaces and boilers, but excess gas is incinerated.
Effective utilization of the low BTU excess tail gas can result in an overall energy efficiency improvement for the carbon black process. Efficiency improvements can also result from effectively integrating waste heat recovery into the carbon black process and limiting quench requirements. Increased efficiency can translate into reduced natural gas requirements or increased carbon black production.
Better utilization of carbon black reactor tail gas has been proposed by several patents in the prior art.
In U.S. Pat. No. 4,261,964, Scott, IV et al. proposed extracting the combustible components (hydrogen and/or carbon monoxide) from the tail gas and replacing 33% to 100% of the natural gas fuel with these components. The method for CO extraction described was a liquid adsorbent process known as COSORB. Hydrogen was recovered from the resultant CO--free tail gas with a cryogenic process.
There are several disadvantages to this process. The solvent CO absorption process (COSORB) is very sensitive to oxygen and water content in the tail gas. Water must be removed from the tail gas with dryers; failure to remove water results in severe corrosion problems in the COSORB equipment due to HCl formation. Oxygen will result in solid precipitates that foul and plug equipment.
The low pressure tail gas (near atmospheric) will require a large absorber column and high solvent circulation rates due to low separation driving force for CO removal. The COSORB solvent requires about 100,000-150,000 BTU/lb mole CO for regeneration. The combination of high energy requirements and high capital makes this recovery method uneconomical.
U.S. Pat. Nos. 4,460,558 and 4,393,034 utilize oxygen enriched air for the carbon black reactor oxidant gas. This minimizes the nitrogen content of the tail gas, upgrading its heating value, and making it suitable for reactor fuel.
Oxygen enrichment also has several disadvantages especially when retrofitting an existing carbon black process. Oxygen enrichment increases combustion chamber temperatures and requires a refractory changeout or the advantages of oxygen enrichment are limited. Oxygen is costly--its cost is about equivalent to the natural gas fuel cost that is replaced. Equipment must be installed to cool and condense water from the tail gas to improve its heating value. The integrated SMR process can retrofit existing carbon black processes without requiring equipment changeout in the carbon black process.
Chen cites in U.S. Pat. No. 4,490,346 a method for using the low BTU content tail gas by combusting with with near stoichiometric amounts of air and then tempering the combustion mixture with diluent tail gas or air before oil injection. A special compact reactor configuration with means for diluent introduction is needed to carry out this process.
The disadvantages of the prior art set forth above have been overcome by the present invention which will be described in greater detail below.

Integrated reformer process for the production of carbon black


A method and system operable for evaluation of an automotive vehicle forward collision threat. The presence of an oncoming vehicle in front of a host vehicle is established and a passing position of the host vehicle for the moment when the vehicles reach each other is predicted. In addition, a free passing distance for free passing of the oncoming vehicle on a first side of the host vehicle is predicted for the situation when the host vehicle is positioned in the passing position. The free passing distance is the minimum distance between the first side of the host vehicle and a road edge. A width of the oncoming vehicle is also estimated. If the free passing distance is equal to or less than a comparison value, it is decided that a forward vehicle collision threat exists. The comparison value is at least equal to the width of the oncoming vehicle.

A current trend in the automotive industry is to introduce active safety systems for avoiding or mitigating collisions. Some of the introduced active safety systems are aimed at avoiding or mitigating forward collisions between a vehicle hosting such a system and an oncoming vehicle. These active safety systems have a potentially large positive impact on accident statistics. Forward collisions between two vehicles may, for example, be due to intentional or unintentional lane changes or to the fact that any of the drivers of the vehicles does not drive completely on the correct side of a road.
In known active safety systems for avoiding or mitigating a forward collision between a host vehicle and an oncoming vehicle, a vehicle forward collision threat evaluation system performs an evaluation of the vehicle forward collision threat before any action in order to avoid or mitigate a collision is executed. Normally, the vehicle forward collision threat evaluation systems utilize one or more sensors based on technologies such as RADAR (RAdio Detection And Ranging), LIDAR (Light Detection And Ranging), LASER (Light Amplification by Stimulated Emission of Radiation) and cameras in order to establish the presence of an oncoming vehicle and estimate parameters such as the distance between the oncoming vehicle and the host vehicle, lateral and longitudinal velocity of the oncoming vehicle, and lateral and longitudinal acceleration of the oncoming vehicle.
Typically, the estimated parameters are utilized for prediction of a future path of the oncoming vehicle. The predicted future path of the oncoming vehicle is then compared with a predicted future path of the host vehicle in order to check if a collision between the host vehicle and the oncoming vehicle is likely to occur, i.e. in order to decide whether there is a vehicle forward collision threat or not. In case it is decided that a vehicle forward collision threat exists, a collision avoidance functionality may be executed by the active safety system. For example, a Forward Collision Warning (FCW) functionality, a Collision Mitigation by Braking (CMbB) or an autonomous steering intervention of the host vehicle may then be executed.
Forward Collision Warning (FCW) is a function that warns the driver in case a collision with a target object seems likely. Collision Mitigation by Braking (CMbB) is a function that automatically applies braking in case a collision with a target object is unavoidable.
However, the above mentioned sensors, which are utilized in order to establish the presence of an oncoming vehicle and to estimate the above mentioned parameters thereof, provide estimations of the lateral velocity and the lateral acceleration of the oncoming vehicle with limited accuracy. This implies in turn that the accuracy of the predicted future path of the oncoming vehicle also is limited since the prediction of the future path is based on the lateral velocity and lateral acceleration (as well as other parameters) estimated by means of any of those sensors.
Furthermore, in order for an action executed in order to avoid a collision, e.g. an FCW, CMbB or autonomous steering intervention, to be effective, it has to be initiated a few seconds (e.g. about three seconds) before an estimated collision time point (or passing time point). Thus, the above mentioned vehicle forward collision threat evaluation has to be performed a few seconds before an estimated collision time point. Thereby, the future path of the oncoming vehicle, which is utilized for comparison with the path of the host vehicle in the evaluation, has to be predicted a few seconds before an estimated collision time point. However, there is an uncertainty of future maneuvers of the oncoming car, i.e. many things can happen during the time between the time point of prediction of the future path of the oncoming vehicle and the time point when the vehicles reach each other, resulting in another actual path of the oncoming vehicle than the predicted path.
Thus, since the predicted future path of the oncoming vehicle has limited accuracy and since there is an uncertainty of future movements of the oncoming vehicle in accordance with the above, the conventional vehicle forward collision threat evaluation, which is based on a comparison of the predicted future path of the oncoming vehicle and the predicted future path of the host vehicle, may easily turn out wrong. For example, it may result in false alarms and interventions. Consequently, there is still a need for another improved approach in automotive forward collision threat evaluations.

System and method for evaluation of an automotive vehicle forward collision threat


A compressor shaft has a fluid inlet that leads into a fluid inlet tube, is perpendicular to a longitudinal hole in the length of the shaft. An intermediate inlet into the longitudinal hole is located between the fluid inlet and an outlet at an end of the longitudinal hole. A drive plate mounted to the compressor shaft has a protruding drive arm, which uses a holding mechanism to connect to a swash plate. At certain swash plate angles, the intermediate inlet is covered and sealed by the swash plate, or uncovered. The drive arm defines an internal bore and a through slot. At opposite ends, the bore merges into the longitudinal hole and open into the through slot. The holding mechanism and/or swash plate guide covers the bore in the slot.

This section provides background information related to the present disclosure which is not necessarily prior art. Compressors used to compress a refrigerant, such as R134a, in an air-conditioning system of a vehicle are known; however, such compressors are not without their share of limitations. One such limitation is the amount of heat stored within the compressor, which is created and held within a swash plate chamber (i.e. crank case) of a variable displacement air conditioning compressor. Prolonged subjection to heat may decrease the useful life of internal compressor parts and thus the useful life of the compressor. By controlling the volume of lubricating oil that is retained within the swash plate chamber, such as during specific volumes of compressor piston displacement, heat generated within the swash plate chamber may be controlled.
Another limitation of air conditioning compressors relates to the amount of oil that is permitted to be discharged from the compressor swash plate chamber and become resident within other components of an attached air conditioning refrigeration system, such as within a condenser and an evaporator. Oil that becomes resident in a condenser and an evaporator may decrease the cooling effectiveness of refrigerant passing through such components because a layer of oil within an internal cavity of such components decreases the heat transfer performance of such components and the overall cooling performance of the air conditioning system. What is needed then is a device that is capable of helping to retain oil within the compressor swash plate chamber when the compressor operates at prescribed compressor displacements.

Variable displacement compressor shaft oil separator


A low-current female socket of the modular jack type comprises a series of eight aligned metal contacts, each of which having a tail and a contact part which extends in female entry mouth and which is adapted to make electrical contact with a metal contact of a plug. The central four metal contacts of the series are shorter contacts that follow a one-way path from their tail, with the contact parts thereof parallel to each other and oriented generally toward the front of the female entry mouth, and the two metal contacts at the ends are longer contacts that follow a path with portions in two opposite directions and whose contact parts are oriented generally toward the rear of the female entry mouth.

1. Field of the Invention
The present invention relates to a low-current female socket of the modular jack type, such as a telephone or computer female socket for connecting a computer or telephone cable of a particular device to a computer or telephone network.
2. Description of the Prior Art
An RJ 45 computer female socket generally has an insulative material body with a female entry mouth adapted to receive an RJ 45 male plug and a series of eight aligned metal contacts, with each metal contact extending freely from a tail at the female entry mouth end and having a contact part adapted to make electrical contact with a metal contact of the male plug.
The eight contacts are connected in pairs to pairs of electrical wires, each of which pairs forms a single electrical circuit.
In some countries, telephone female sockets comprise only four or six metal contacts in an insulative material body of the same type as the computer female socket described above (RJ 11 or RJ 12 female socket).
They are then adapted to receive an RJ 11 or RJ 12 male plug with four or six metal contacts.
Also, in these countries, telephone and computer installations of open-plan or modular offices often use only RJ 45 computer female sockets with eight metal contacts to transmit computer data and telephone data.
In this case, RJ 11 or RJ 12 telephone male plugs, which are narrower than RJ 45 computer male plugs, are inserted into RJ 45 computer female sockets, of which only four or six metal contacts are used.
However, if an RJ 11 or RJ 12 male plug is inserted into an RJ 45 female socket, its insulative body crushes the metal contacts at the end of the RJ 45 female socket, which are not used, and are therefore subjected to high deformation stresses.
Although the metal contacts of RJ 45 female sockets have electrically deformable branches, it often happens that when an RJ 11 or RJ 12 male plug is inserted into an RJ 45 female socket these end metal contacts exceed their elastic limit and therefore become unusable with an RJ 45 male plug.
Also, when transmitting high-frequency signals, crosstalk can occur between the various pairs of metal contacts of an RJ 45 low-current female socket in contact with the corresponding metal pairs of the RJ 45 male plug.
Crosstalk degrades message transmission and increases with the operating frequency of the computer female sockets.
Crosstalk is favored by the proximity of parallel lengths of metal contacts, since the phenomenon is due to an induced current. The critical pairs of metal contacts are usually the central pairs of metal contacts, one of which comprises contacts 3 and 6 and the other of which comprises contacts 4 and 5. In these pairs of metal contacts, each metal contact is between other metal contacts.
There are various prior art solutions to the problem of crosstalk.
One solution is to cross the metal contacts concerned over at particular locations to create an induced current with the opposite phase to cancel the induced current that causes crosstalk when transmitting high-frequency signals.
Another prior art solution is to reduce the parallel lengths of the metal contacts.
Finally, a further prior art solution is to provide appropriate compensation circuits on a printed circuit card in the low-current female socket.
In order to alleviate all of the drawbacks previously referred to, the present invention proposes a new low-current female socket of the modular jack type adapted to be used with a male plug with eight, six or four metal contacts without damaging the end metal contacts, and which offers good performance in terms of transmission of high-frequency signals.
The present invention provides a low-current female socket of the modular jack type comprising an insulative material body having a female entry mouth adapted to receive a male plug and a series of eight aligned metal contacts, each metal contact having a tail and a contact part which extends in said female entry mouth and which is adapted to make electrical contact with a metal contact of the male plug, wherein the central four metal contacts of the series, forming two pairs of contacts connected to respective pairs of electrical wires, are shorter contacts that follow a one-way path from their tail, with the contact parts thereof parallel to each other and oriented generally toward the front of the female entry mouth, and the two metal contacts at the two ends of the series are longer contacts that follow a path with portions in two opposite directions and whose contact parts are oriented generally toward the rear of the female entry mouth.
Accordingly, the end two metal contacts of the low-current female socket according to the invention are able to withstand the considerable elastic deformation caused by inserting into the female entry mouth of the female socket an RJ 11 or RJ 12 male plug, and the four central metal contacts of the low-current female socket are short, which improves the quality of transmission of high-frequency signals by minimizing the induced current.
Other non-limiting and advantageous features of the present invention are as follows:
the two pairs of end metal contacts, each adapted to be connected to a pair of electrical wires, are pairs of longer contacts that follow a path with portions in two opposite directions and whose contact parts are parallel to each other and oriented generally toward the rear of the female entry mouth;
each contact part of each longer contact of the series has one end free of any mechanical interengagement with any insulative support;
each end metal contact has the general shape of a hairpin with two different length branches connected together by a connection forming a hinge, the shorter branch is oriented toward the rear of the female entry mouth and constitutes the contact part, and the longer branch is situated to the rear of the shorter branch;
the contact part of each end metal contact is bent toward the rear of the female entry mouth;
the contact parts of the central metal contacts have at their end a beak adapted to bear against an insulative support;
the contact parts of the central metal contacts are crenellated;
the contact part of each end metal contact is shorter than the contact part of each central metal contact;
the contact parts of the central metal contacts are all the same length and the contact parts of the end metal contacts are all the same length;
the metal contacts are attached to an insulative plate and the tails of the metal contacts emerge from the insulative plate toward the rear of the body and are pinhead-shaped so that they can be force-fitted into orifices in a printed circuit support plate;
the tails of the metal contacts are arranged in a quincunx on the insulative plate and each central metal contact has a part for taking up play between its tail and its contact part; and
the female socket further includes an insulative support with eight slots adapted to receive the metal contacts and to be received in an opening at the rear of the body.
The following description with reference to the accompanying drawings, which are provided by way of non-limiting example only, explain in what the invention consists and how it can be put into effect.

Low-current female socket of the modular jack type

Arnould Fabrique d""Appareillage Electrique


The present invention provides a method of bioluminescence-driven optogenetic control of excitable cells. The excitable cell expresses a light-gated ion channel, and a luminescent protein can be expressed either in the excitable cell or in another cell proximal to the excitable cell. The methods of the invention can be used to desynchronize local activity of excitable cells in a mammalian tissue. The methods of the invention can be used to treat a disease or condition in a mammal, the disease or condition being related to bursting. The disease or condition can be Parkinson's disease, epilepsy, a sleep disorder, or a sensory-related disease or condition (e.g., attention deficit disorder or pain). The invention also provides a conjugate of containing a voltage-gated ion channel and a luminescent protein.

Polarization of excitable cells (e.g., neurons) plays a role in symptoms of various diseases or conditions (e.g., Parkinson's disease, epilepsy, sleep and sensory-related maladies such as pain and attention deficit disorders). While etiologies of these diseases or conditions may differ, their manifestation can involve the same basic processes, such as hyperpolarization of excitable cells. For example, increases in bursting (brief periods of high-frequency action potential activity) are prominent in epilepsy and Parkinson's disease. Epileptic seizures are believed to be driven by hyper-synchronized bursting in the thalamic reticular nucleus (TRN) and in thalamic relay neurons that project to the neocortex. In Parkinson's disease patients, bursting occurs in subthalamic nucleus and increases after dopamine depletion.
Modulation of polarization of excitable cells has been the focus of many studies in the field of optogenetics. Existing optogenetic approaches typically up- or down-regulate activity of cells in a tissue en masse and thus can up- or down-regulate the activity of cells that are not in need thereof. Moreover, delivery of light often requires the use of chronic implanted devices, which may be fully or partially implanted. If automatic control of optogenetic control is desired in a device, additional elements, such as implanted electrodes, may be required, rendering such approaches invasive.
There remains a need for minimally invasive methods of optogenetic control, preferably automatic control that requires little input from patient or medical personnel. The methods capable of providing targeted optogenetic control are particularly desirable. The present invention can provide optogenetic control with the desirable characteristics described herein.

Minimally-invasive and activity-dependent control of excitable cells


A method used in equalization processing is provided, in which a reference signal is received and a change point of transmission line characteristics is detected. A basic frequency signal of fluctuation period of the transmission line characteristics is extracted, and vectorized. The vector is adjusted such that vectors corresponding to two change points become symmetrical with respect to X axis. Then, fluctuation interval of transmission line characteristics is judged by comparing X component of the vector with a reference value. As a result, equalization processing is performed in accordance with the fluctuation.

1. Field of the Invention
The present invention relates to an equalization processing method and an equalization processing apparatus for periodical fluctuation of transmission line characteristics.
More particularly, an equalization characteristic changing method and the apparatus for detecting fluctuation of transmission line characteristics and changing the equalization characteristic according to the fluctuation of transmission line characteristics, wherein the fluctuation of transmission line characteristics periodically occurs, in a modem and the like for a power line communication, due to on-off of internal elements of a household electrical appliance which is connected to a power line such as a switching power source and the like.
2. Description of the Related Art
FIG. 1 shows a configuration example of a power line communication system. As shown in the figure, a high voltage power line 8-2 of 6.6 kV is provided between a distribution substation 8-1 and a pole transformer 8-3, and a low voltage distribution line 8-4 of 100V/200V and a service line 8-5 are provided between the pole transformer 8-3 and a house 8-6.
In the power line communication system, an optical fiber is provided in parallel with the high voltage distribution line 8-2 between an access node 8-11 in the distribution substation 8-1 and a modem in the pole transformer 8-3 so that an optical signal is transmitted. A communication signal is transmitted between the pole transformer 8-3 and a modem plugged in a wall outlet in the house 8-6 via the low voltage distribution line 8-4 of 100V/200V, the service line 8-5 and an interior distribution line 8-7.
In such a power line communication system, the low voltage distribution line 8-4 can be regarded as inductor for the modem in the pole transformer 8-3. In addition, the service line 8-5 which is connected to the low voltage distribution line 8-4 and the interior distribution line 8-7 can be regarded as a condenser. In addition, household electrical appliances show large capacitive load since condensers for preventing noise are connected between AC 100V lines.
As a result, the low voltage distribution line 8-4 is regarded as a low-pass filter (LPF) by the pole transformer 8-3 so that there is a case where a receive signal of the modem connected to the interior distribution line 8-7 is buried in noise since high frequency component is largely attenuated. On the other hand, low frequency component is not much attenuated comparing with the high frequency component. However, communication quality of the low frequency component degrades since random noise (colored noise) is released from switching power sources or inverter circuits of the household electrical appliances so that the low frequency component is also buried in large noise. Therefore, taking measures against the noise is necessary for realizing high speed data communication by the power line carrier.
For taking measures against degradation of the receive signal, frequency modulation (FM), frequency-shift keying (FSK), phase-shift keying (PSK) and the like which are said to be strong for noise are adopted conventionally as modulation method of the modem for power line communication. However, since noise level of power line is high, thus, applications which are realized by these modulation methods are limited to low speed applications under 1200 bps.
In addition, spread spectrum technology has been used for the power line communication. However, transmission capacity decreases remarkably when S/N value becomes minus under white noise environment. Thus, data can be sent at 100 kbps at the maximum, and communication is interrupted at worst. In addition, an attempt has been made to apply a technology to avoid carrier band in which noise is high, by using OFDM (Orthogonal Frequency Division Multiplexing) which uses multi-carrier modulation method.
However, the switching power sources in the household electrical appliance and the inverter circuits tend to increase. Conventional technology can be used for low speed communication even when noise and fluctuation of transmission line characteristics due to switching of the power sources and the inverter circuits occurs. However, it is not possible to realize the power line communication at high speed of several Mbps.
The switching power sources and the inverter circuits in the household electrical appliance are more and more increasingly used. In addition, condensers are connected to 100V power source lines for preventing noise so that capacitive load is increasing. Under these circumstances, it is not enough to avoid noise for communication in the way as conventional technology. On the other hand, it is more effective to realize high speed communication by actively coping with the occurrence of noise and fluctuation of transmission line characteristics so as to increasing receiving accuracy of a signal.

Equalization processing method and the apparatus for periodic fluctuation of transmission line characteristic


A method for triggering a heterodyne interferometer having two acousto-optical modulators in separate light paths, a receiver generating an analog signal and a downstream A/D converter converting the analog signal into a digital signal is described. The one acousto-optical modulator is triggered at a modulation frequency f1 and the other acousto-optical modulator is triggered at another modulation frequency f2, the difference between modulation frequencies f1 and f2 forming a heterodyne frequency fHet and the analog signal being converted into the digital signal in the A/D converter at sampling frequency fa. In such a heterodyne interferometer, a fixed ratio of modulation frequencies is maintained, and they are prevented from shifting due to aging and drift by forming at least two of the frequencies of modulation frequencies f1, f2 and sampling frequency fa from a fundamental frequency fqartz of a common oscillator. As a result, it is also possible for sampling frequency fa to be in a fixed phase ratio to the differential frequency of modulation frequencies f1, f2, of heterodyne frequency fHet. Measurement accuracy is increased because sampling is performed at a constant phase, independently of drift and aging.

Heterodyne interferometers are used to measure the phase shift of a beam of light caused by an optical phase shifter. An optical bypass line whose length is to be measured may function as an optical phase shifter. Heterodyne interferometers are generally conventional.
In a heterodyne interferometer, the beam of a light source, usually a laser, is passed through a beam splitter to two acousto-optical modulators. The two acousto-optical modulators are triggered by frequencies f1 and f2 which are typically in the MHz range. The beams of light at the output of the acousto-optical modulators are shifted here by a corresponding frequency with respect to the original light frequency.
The two frequency-shifted beams of light are then sent back to a beam splitter via mirrors and combined, one of the two beams being delayed via an optical phase shifter. This may be accomplished via materials which shift the phase of light or with which the speed of the light with respect to air is reduced. According to another embodiment, the light is deflected by additional mirrors and must therefore travel through an optical bypass. After the two beams of light have been combined again by the beam splitter, e.g., in the form of a semitransparent mirror, the light is sent to a receiver containing a photodetector and usually an amplifier.
The two beams of light cause interference and generate a beat frequency known as a heterodyne frequency fHet in the receiver. This frequency is calculated as follows:fHet=|f1−f2|.The phase of this signal, based on the phase angle of an electric signal of frequency fHet obtained by mixing f1 with f2, corresponds to the phase shift of the optical phase shifter that is to be measured.
The analog signal available at the output of the receiver is sent to a downstream A/D converter which generates a digital signal. The conversion is then performed at a sample rate of frequency fa. The digital signal is then sent to an analyzer unit for further processing.
In the case of the heterodyne interferometers described above, generating frequencies f1, f2 and fa during operation may result in great fluctuations in heterodyne frequency fHet=|f1−f2| because the oscillators may have frequency drift with temperature and also with aging. Another disadvantage is that blanking frequency fa does not form an integral ratio with heterodyne frequency fHet and is not even constant.

Triggering for a heterodyne interferometer


A screw spindle pump, including a housing and a drive spindle accommodated therein and at least one running spindle which meshes with the latter and which has in each case two terminal end surfaces. A stop surface is provided axially adjacent to at least one end surface of the running spindle, wherein the running spindle is accommodated displaceably with an axial clearance perpendicular to the stop surfaces.

The invention relates to a screw spindle pump, comprising a housing and a drive spindle accommodated therein and at least one running spindle which meshes with the latter and which has in each case two terminal end surfaces.
Screw spindle pumps are used for conveying a very wide variety of substances, primarily fluid media. A screw spindle pump is known to comprise a housing in which the spindle set, comprising a drive spindle, which is led out of the housing and is coupled to a drive motor, possibly with a gear mechanism interposed, and comprising one or more running spindles, the spindle profiles of which mesh with the spindle profile of the drive spindle and which are driven via the drive spindle. The housing in which the spindle set is accommodated may be the pump housing, which also terminates outwardly, or a housing designed as an insert into an outer housing.
Normally, the one running spindle or the multiple running spindles, generally two running spindles arranged in a parallel manner and so as to be offset by 180° next to the drive spindle, is/are hydraulically supported axially, for which purpose there may be provided adjacent to the end surface of the respective running spindle a nozzle orifice via which a fed proportion of the fluid to be conveyed flows against the spindle end surface in order, in this way, to build up an axial support pressure via which the respective running spindle is supported axially. This necessitates a corresponding formation of the housing, in which a corresponding fluid supply has to be provided via suitable channels, as well as the corresponding nozzle orifices, which, for the generation of the corresponding fluid pressure, also have to be designed and configured in a geometrically corresponding manner.
Screw spindle pumps are increasingly being used also in the food sector and the pharmaceutical sector, that is to say that they are used for conveying corresponding fluid foodstuffs or pharmaceutical substances. Working with such substances requires the highest level of hygiene, and for this reason the screw spindle pumps used also have to be cleaned at correspondingly short intervals. Owing to the complex configuration of the screw spindle pump with regard to the fluid guide means for axial support of the running spindles, which comprises corresponding channels, etc., it is necessary for the purpose of cleaning for the screw spindle pump to be removed and dismantled and cleaned, in order to ensure that cleaning is realized in all regions. This is because, owing to the integration of the additional channels, nozzle orifices, etc, there is a considerable volume which does not participate in the actual conveying process, that is to say is effectively present as dead space, but is nevertheless charged with the fluid.

Screw spindle pump having a stop surface axially adjacent to an end surface of a running spindle


A golf club head comprising an aerodynamic hosel is disclosed herein. In one embodiment, the hosel may have an airfoil cross-section with a high thickness to chord ratio. In a further embodiment, the thickness to chord ratio may increase from a hosel head connection point to a hosel shaft connection point. In another embodiment, a shaft connection point of the hosel is closer to a club face vertical plane than to a head connection point vertical plane, e.g., is swept. In yet another embodiment, the hosel has an endplate proximate a shaft connection point. In yet another embodiment, the exterior surface of the hosel is rough, comprises at least one vertex generator, comprises a fillet, or comprises at least one trip step.

1. Field of the Invention
The present invention relates to a golf club head having a hosel configuration that improves the aerodynamic qualities of the golf club head.
2. Description of the Related Art
Technical innovation in the size, structure, configuration, material, construction, and performance of golf clubs has resulted in a variety of new products. The contribution of the hosel to overall drag of a club head can be significant, but it has largely been ignored by manufacturers and innovators even though the advent of adjustable hosel configurations with increased dimensions has resulted in a larger contribution to club head drag for some club head models. For low drag head shapes the contribution of the hosel becomes more important.
The hosel of a golf club head is the connection between the shaft and the head. It is typically circular in cross-section with a diameter that is larger than the shaft. Both tapered and constant cross-section approaches can be used. The hosel is a relatively small subcomponent of a golf club head, but it essentially travels at the same high speed as the head and is usually has a very aerodynamically inefficient shape. In addition, it operates in a flow field that is heavily influenced by larger club heads, particularly in drivers.
Although the prior art has disclosed many variations of golf club heads, including a variation disclosed in U.S. Pat. No. 1,587,758 (entitled "Golf Club") to Charavay, the prior art has failed to provide a club head with a hosel configuration that does not interfere with or have a negative effect on airflow during a swing.

Golf club head with improved aerodynamic characteristics


The present invention relates to novel polymorphic forms of ivacaftor, process for its preparation and pharmaceutical compositions comprising the same.

Ivacaftor, also known as N-(2,4-di-tert-butyl-5-hydroxyphenyl)-1,4-dihydro-4-oxoquinoline-3-carboxamide, having the following Formula I:

Ivacaftor was approved by FDA and marketed by Vertex pharma for the treatment of cystic fibrosis under the brand name KALYDECO® in the form of 150 mg oral tablets.
WO2006/002421 publication discloses modulators of ATP-binding cassette transporters such as ivacaftor. This patent generally discloses a process for the preparation of modulators of ATP-binding cassette transporters such as quinoline compounds; however, specific process for the preparation of ivacaftor and its solid state details were not specifically disclosed.
WO2007/079139 publication discloses Form A, Form B and amorphous form of ivacaftor characterized by PXRD, DSC and TGA and process for their preparation. Further this publication discloses ethanol crystalate of ivacaftor in example part.
WO2009/038683 publication discloses the solid forms of ivacaftor, which are designated as Form-I (2-methylbutyric acid), Form-II (propylene glycol), Form-III (PEG400.KOAc), Form-IV (lactic acid), Form-V (isobutyric acid), Form-VI (propionic acid), Form-VII (ethanol), Form-VIII (2-propanol), Form-IX (monohydrate), Form-X (besylate Form A), Form-XI (besylate Form B), Form-XII (besylate Form D), Form-XIII (besylate Form E), Form-XIV (besylate Form F), Form-XV (besylate (2:1)), Form-XVI (besylate mono hydrate). This publication also discloses the characterization details like PXRD, DSC and TGA for the above forms and process for their preparation.
WO2011/116397 publication discloses crystalline Form C of ivacaftor, process for its preparation and pharmaceutical composition comprising the same. Also discloses characterization details of Form C, such as PXRD, IR, DSC and 13CSSNMR.
WO2013/158121 publication discloses solvated forms of ivacaftor, which are designated as Form D (acetonitrile or acetonitrile/water (75/25) solvate), Form E (Methyl ethyl ketone (MEK), MEK/water (90/1), MEK/water (90/10), MEK/water (80/20) solvate), Form F (acetonitrile/water (75/25) solvate), Form G (isopropyl acetate solvate), Form H (isopropyl acetate/water (95/5) solvate), Form I (MEK solvate), Form J (MEK/water (99/1) solvate), Form K (MEK or MEK/water (99/1) or MEK/water (90/10) or MEK/water (80/20) solvate), Form L (isopropyl acetate/water (95/5) solvate), Form M (MEK or MEK/water (99/1) solvate), Form N (MEK/water (90/10) or MEK/water (80/20) solvate), Form O (MEK or MEK/water (99/1) solvate), Form P (MEK/water (90/10) or MEK/water (80/20) solvate), Form Q (MEK/water (80/20) solvate), Form R (acetonitrile solvate), Form S (MEK/water (80/20) solvate), Form T (isopropyl acetate/water (95/5) solvate), Form W (acetonitrile/water (90/10) solvate), Form XX (from 10% water/acetonitrile) and hydrate B (hydrated form). This patent further discloses characterization details like PXRD and TGA for the above forms and process for their preparation.
WO2014/118805 publication discloses crystalline forms of ivacaftor designated as Form D, Form E, Form E1, Form G and Form G′; amorphous ivacaftor designated as Form I and Form II; crystalline ivacaftor solvates such as n-butanol solvate, methanol solvate, propylene glycol solvate, DMF solvate, THF solvate, DMF:ethylacetate solvate. This publication further discloses the process for the preparation of said forms along with their characterization details.
WO2015/070336 publication discloses polymorphic form APO-I and MIBK solvate of ivacaftor along with its characteristic PXRD details, process for its preparation and pharmaceutical composition comprising them.
CN 104725314A publication discloses ivacaftor new polymorph D, which is obtained by crystallization of ivacaftor from acetonitrile/water. This publication further discloses characteristic details such PXRD, IR and DSC of ivacaftor new polymorph D.
Polymorphism is the occurrence of different crystalline forms of a single compound and it is a property of some compounds and complexes. Thus, polymorphs are distinct solids sharing the same molecular formula, yet each polymorph may have distinct physical properties. Therefore, a single compound may give rise to a variety of polymorphic forms where each form has different and distinct physical properties, such as different solubility profiles, different melting point temperatures and/or different x-ray diffraction peaks. Since the solubility of each polymorph may vary, identifying the existence of pharmaceutical polymorphs is essential for providing pharmaceuticals with predictable solubility profiles. It is desirable to investigate all solid state forms of a drug, including all polymorphic forms and solvates, and to determine the stability, dissolution and flow properties of each polymorphic form.
Polymorphic forms and solvates of a compound can be distinguished in a laboratory by X-ray diffraction spectroscopy and by other methods such as, infrared spectrometry. Additionally, polymorphic forms and solvates of the same drug substance or active pharmaceutical ingredient, can be administered by itself or formulated as a drug product (also known as the final or finished dosage form), and are well known in the pharmaceutical art to affect, for example, the solubility, stability, flowability, tractability and compressibility of drug substances and the safety and efficacy of drug products.
The discovery of new polymorphic forms and solvates of a pharmaceutically useful compound, like ivacaftor, may provide a new opportunity to improve the performance characteristics of a pharmaceutical product. It also adds to the material that a formulation scientist has available for designing, for example, a pharmaceutical dosage form of a drug with a targeted release profile or other desired characteristic. New polymorphic forms of the ivacaftor have now been discovered and have been designated as ivacaftor Form-L1, Form-L2, Form-L3, Form-L4, Form-L5, Form-L6, Form-L7, Form-L8, Form-L9, Form-L10, Form-L11, Form-L12A, Form-L12B, Form-L13 and Form-L14.

Polymorphs of Ivacaftor, process for its preparation and pharmaceutical composition thereof


A tandem rolling bearing including a first rolling element subassembly and a second rolling element subassembly is provided. The subassemblies both include a plurality of rolling elements and a cage. The cages each include a ring and a plurality of axial projections having axial free ends. The free ends of the cages in the first and second subassemblies face each other. Rolling element retaining pockets are defined between adjacent pairs of projections in the cages. The projections include pairs of lugs that, together with a partially spherical retaining surface provided between the projections of each of the pockets, contact and retain the rolling elements in the pockets.

Rolling bearings are widely used in various mechanical applications, including the automotive field. Tandem rolling bearings include two rows of rolling elements. The two rows are arranged in a stepped-manner, axially offset in relation to one another. These rows generally include cages for retaining and separating the rolling elements in the circumferential direction. A subset of this is tandem ball bearings where the rolling elements are balls. Tandem ball bearing assemblies can include a small and large rolling element subassembly. Each subassembly includes a cage and a plurality of the rolling elements. Retention of the rolling element subassemblies depends on the diametrical interference between the retention diameter of the smaller rolling element subassembly, defined as the diameter formed on the radially inner surface of the rolling elements, and the diameter of a retention element formed on an axial end of the inner ring. Slight deviations of the retention diameter of the smaller rolling element subassembly, due to geometric tolerances, moisture absorption, and/or thermal expansion, can cause excessive or inadequate retention of the smaller rolling element subassembly on the inner ring.
Cages for separating rolling elements are typically made from plastic in an injection-molding process. U.S. Patent Application 2010/0189386 A1 discloses an angular-contact ball bearing in a tandem arrangement. The two main types of cages currently used in rolling bearing assemblies are closed and open. Closed cages retain rolling elements in the circumferential direction and both axial directions. When installed in a bearing assembly, the rolling elements arranged in a closed cage are retained about a given axis by either the cage or the races of the rings. U.S. Pat. No. 6,783,279 B2 discloses a closed cage tandem rolling bearing where closed cages retain the rolling elements. These closed cages require additional space between the rolling element subassemblies to maintain necessary clearance during operation. Because of their configuration, closed cages are often stiffer than similarly sized open cages. As a result, closed cages are more sensitive with respect to their retention properties than open cages, and the retention forces provided by closed cages are greater than open cages.
Open cages separate rolling elements in the circumferential direction and retain the rolling elements on one axial side. U.S. Patent Application 2010/0296761 A1 discloses an open cage tandem rolling bearing. These open cages do not retain rolling elements in the outer radial direction and both axial directions.
Providing retention of the rolling elements in the outer radial direction as well as in the axial directions would be desirable during installation of cage subassemblies onto an inner ring of a bearing assembly.
It would also be desirable to retain the rolling elements in the cages during the installation of the subassemblies onto the outer ring. After the rolling element subassemblies are secured on the inner ring, this inner ring subassembly is dropped a short distance down a shaft with the smaller rolling element subassembly facing down. The inner ring subassembly comes to rest at an intermediate position before being pressed into position with the outer ring. Retention of the smaller rolling element subassembly on the seat of the smaller race of the inner ring during installation is necessary.
Therefore, a need exists for a tandem rolling bearing having the advantages of both the open and closed cages. A need exists for a cage for a tandem rolling bearing that does not have the increased width requirements or stiffness provided by the closed cages that still provides improved retention of the rolling elements during assembly.