Apparatus for monitoring a plurality of tissue viability parameters of a tissue layer element, in which two different illumination sources are used via a common illumination element in contact with the tissue. One illumination source is used for monitoring blood flow rate and optionally flavoprotein concentration, and collection fibers are provided to receive the appropriate radiation from the tissue. The other illuminating radiation is used for monitoring any one of and preferably all of NADH, blood volume and blood oxygenation state of the tissue element, and collection fibers are provided to receive the appropriate radiation from the tissue. In one embodiment, the wavelengths of the two illumination sources are similar, and common collection fibers for the two illuminating radiations are used. In another embodiment, the respective collection fibers are distanced from the illumination point at different distances correlated to the ratio of the first and second illuminating wavelengths.

Mammalian tissues are dependent upon the continuous supply of oxygen and glucose needed for the energy production. This energy is used for various types of work, including the maintaining of ionic balance and biosynthesis of various cellular components. The ratio or balance, between oxygen supply and demand reflects the cells' functional capacity to perform their work. In this way, the energy balance reflects the metabolic state of the tissue. In order to assess the tissue energy balance, it is necessary to monitor the events continuously using a multiparametric system in real-time.
The integrated system of energy supply and demand can be understood by considering the various components thereof.
O2 supply: The blood carries the oxygen and other essential substances to the cells. Therefore, monitoring of blood flow rate, blood volume and blood oxygenation will reflect the supply of O2 to the tissue for the purpose of energy formation therein.
Energy production and demand: In an inner compartment of the cells, called the mitochondria, the glucose and O2 are transformed into ATP, a form of energy which can be used by the cells for various types of activities. The ATP production rate is, in normal states, regulated by rate of consumption of ATP, and is increased when cellular activity rises. In most pathological states, the limiting factor for this process is O2 availability.
The process of energy (ATP) production and consumption can be determined through monitoring of Nicotineamide adenine dinucleotide (NADH) redox state. The NADH and NAD molecules can be correlated with the process of ATP production. The concentration of the reduced form of the molecule (NADH) rises when the rate of ATP production is low, and is unable to meet the demand in the tissue or cells.
A complementary indicator of energy production, other than NADH, is the concentration of flavoproteins (Fp). Flavoprotein molecules are also linked to the production of ATP in the mitochondria. Fp concentration drops when the rate of ATP production is reduced, and is unable to meet the demand in the tissue or cells.
There is direct correlation between energy metabolism of the cellular compartment and the blood flow in the microcirculation of the same tissue. In a normal tissue, any change in the O2 demand will be compensated by a corresponding change in the blood flow to the tissue. By this mechanism, the O2 supply remains constant if there is no change in the O2 consumption. Any change in the abundance of O2 in the tissue, in other words a change in energy state, will be reflected by the NADH and Fp level.
It is important to monitor both supply and demand in order to be able to detect pathological situations in which the balance is disrupted, and one component of the system reacts abnormally with respect to the other.
The parameters used in the art for the assessment of tissue vitality include: A—Blood Flow Rate; B—Mitochondrial Redox State via the NADH level; C—Blood Volume; D—Blood Oxygenation State; E—Mitrochondrial Redox State via flavoprotein level.
A—Blood Flow Rate
The blood flow rate relates to the mean volume flow rate of the blood and is essentially equivalent to the mean velocity multiplied by the number of moving red blood cells in the tissue. This parameter may be monitored by a technique known as Laser Doppler Flowmetry, which is based on the fact that light reflected off moving red blood cells (RBC) undergoes a small shift in wavelength (Doppler shift) in proportion to the cell's velocity. Light reflected off of stationary RBC or bulk stationary tissue, on the other hand, does not undergo a Doppler shift.
By illuminating with coherent light, such as a laser, and converting the intensities of incident and reflected light to electrical signals, it is possible to estimate the blood flow from the magnitude and frequency distribution of those signals (U.S. Pat. No. 4,109,647; Stem, M. D. Nature 254, 56–58, 1975).
B—Mitochondrial Redox State or the NADH Level
The level of Nicotineamide adenine dinucleotide (NADH), the reduced form of NAD, is dependent both on the availability of oxygen and on the extent of tissue activity. Referring to FIG. 1, whilst NADH absorbs UV light at wavelengths of about 300 nm to about 400 nm and fluoresces at wavelengths of about 400 nm to about 550 nm, the NAD does not fluoresce. The NADH Level can thus be measured using Mitochondrial NADH Fluorometry. The conceptual foundations for Mitochondrial NADH Fluorometry were established in the early 50's and were published by Chance and Williams (Chance B., & Williams G. R., Journal of Biological Chemistry, 217, 383–392, 1955). They defined various metabolic states of activity and rest for in-vitro mitochondria.
An increase in the level of NADH with respect to NAD and the resulting increase in fluorescence intensity indicate that insufficient Oxygen is being supplied to the tissue. Similarly, a decrease in the level of NADH with respect to NAD and the resulting decrease in fluorescence intensity indicate an increase in tissue activity.
C—Blood Volume
The blood volume parameter refers to the concentration of the blood in the tissue. When tissue is irradiated, the intensity R of reflection of the excitation wavelength light from the tissue is informative of the blood volume. The intensity R of the reflected signal, also referred to as the total backscatter, increases dramatically as blood is eliminated from the tissue as a result of the decrease in haemoglobin concentration. Similarly, if the tissue becomes more perfused with blood, R decreases due to the increase in the haemoglobin concentration.
D—Blood Oxygenation State
The blood oxygenation state parameter refers to the relative concentration of oxyhaemoglobin to deoxy-haemoglobin in the tissue. It may be assessed by the performance of photometry measurements. The absorption spectrum of oxyhaemoglobin HbO2 is considerably different from the absorption spectrum of deoxy-haemoglobin Hb (Kramer R. S. and Pearlstein R. D., Science, 205, 693–696, 1979). The measurement of the absorption at one or more wavelengths can thus be used to assess this important parameter. Blood oximeters are based on measurement of the haemoglobin absorption changes as blood deoxygenates (Pologe J. A., Int. Anesthesiol. Clin., 25(3), 137–53, 1987). Such oximeters generally use at least two light wavelengths to probe the absorption. One known method uses one wavelength at an isosbestic point and another wavelength at a point that exhibits absorption changes due to variation in oxygenation level. Another technique uses wavelengths at both sides of an isosbestic point in order to increase measurement sensitivity. The wavelengths used in commercial pulse oximeters are typically around 660 nm in the red region of the spectrum, and between 800 to 1000 nm in near-infrared region (Pologe, 1987).
Isosbestic point as referred to herein is a wavelength at which the intensity of absorption of oxyhaemoglobin HbO2 is the same as the intensity of absorption of deoxy-haemoglobin Hb; to such isosbestic points are indicated as IPA and IPB in FIG. 10. Similarly, there is an isosbestic range marked IR in FIG. 10 where these two functions are substantially coincident. FIG. 10 is based on Anderson, R. R., Parrish, J. A. (1981) Microvasculature can be selectively damaged using dye lasers: a basic theory and experimental evidence in human skin. Lasers Surg. Med. 1, 263–276.
For monitoring the oxygenation levels of internal organs, fiber-optic blood oximeters have been developed. These fiber-optic devices irradiate the tissue with two wavelengths, and collect the reflected light. By analysis of the reflection intensities at several wavelengths the blood oxygenation is deduced. The wavelengths used in one such system were 585 nm (isosbestic point) and 577 nm (Rampil I. J., Litt L., & Mayevsky A., Journal of Clinical Monitoring, 8, 216–225, 1992). Another blood oximeter measures and analyzes the whole spectrum band 500–620 nm (Kessler M. & Frank K., Quantitative spectroscopy in tissue pp. 61–74. Verlagsgruppe GmbH, Frankfurt au Main, 1992). These devices are relatively complicated and susceptible to interference from ambient light, as well as various electronic and optic drifts. Two light sources are required, and the light sources and the detection system also incorporate optical filters that are interchangeable by mechanical means.
E—Flavoprotein Concentration
In order to determine the metabolic state of various tissues in-vivo it is also possible to monitor the fluorescence of another cellular fluorochrome, namely Flavoproteins (Fp). Referring to FIG. 12, Fp absorbs light at wavelengths of about 400 nm to about 470 nm and fluoresces at wavelengths of about 490 nm to about 580 nm. The Fp level can thus be measured using Fp Fluorometry. The conceptual foundations for Fp Fluorometry were established in the late 1960's and were published in several papers as will be referenced hereinafter. Simultaneous monitoring of NADH and Fp from the same layer or volume of tissue provides better interpretation of the changes in energy production and demand.
Chance et al.(B. Chance, N. Graham, and D. Mayar. A time sharing fluorometer for the readout of intracellular oxidation-reduction states of NADH and Flavoprotein. The Review of Scientific Instruments 42 (7):951–957, 1971) used a time-sharing fluorometer to record intracellular redox state of NADH and Fp. They showed a very clear correlation between the two chromophores to changes in O2 supply to the perfused liver. Using a time sharing fluorometer reflectometer simultaneous monitoring of NADH and Fp was performed from the surface of the rat's brain (A. Mayevsky. Brain energy metabolism of the conscious rat exposed to various physiological and pathological situations. Brain Res. 113:327–338, 1976). The kinetics of the responses to anoxia or decapitation were identical for the NADH and Fp indicating that the NADH signal comes from the same cellular compartment as the Fp—the mitochondrion.
The five tissue viability parameters described above represent various important biochemical and physiological activities of body tissues. Monitoring them can provide much information regarding the tissues' vitality. For the monitoring of different parameters to have maximum utility however, the information regarding all parameters is required to originate from substantially the same layer of tissue, and preferably the same volume of tissue, otherwise misleading results can be obtained. In general, the more parameters that are monitored from the same tissue volume or layer, the better and more accurate an understanding of the functional state of the tissue that may be obtained.
There are several techniques that relate to the simultaneous in-vivo measuring of multiple parameters in certain tissues, which can be used for the various pathological situations arising in modem medicine.
The prior art teaches a wide variety of apparatuses/devices which monitor various parameters reflecting the viability of the tissue. For example, U.S. Pat. No. 4,703,758 teaches the use of an apparatus for monitoring blood flow by using a light source to emit a beam of light, and a light detector that measures the light received. This provides the value of the intensity of the transmitted light, which inter alia depends upon the blood flow in the path of the light.
U.S. Pat. No. 4,945,896 teaches the use of a multiprobe sensor, using independent microelectrodes implanted inside the brain tissue, for measuring various parameters indicative of the function of the brain. This device includes a laser Doppler flow probe for measuring cerebral blood flow, and a probe for monitoring redox state (NADH). These probes can be mounted sequentially, i.e., one after another in the same housing, or they can be placed side by side. These devices suffer from a major drawback however. Tissue viability is not merely a reflection of various values of parameters measured at different times in one place, or different places at one time. The complex biochemical mechanisms that determine tissue viability are such that short time deviations between measurement at short distances between points of measurement can provide inaccurate or even misleading information. Thus, while the values of blood flow and redox state (NADH) must be monitored simultaneously at the same location, with the monitoring being for the same layer of tissue, this is not performed in the reference.
Another drawback encountered in NADH measurements is the Haemodynamic Artifact. This refers to an artifact in which NADH fluorescence measurements in-vivo are underestimated or overestimated due to the haemoglobin present in blood circulation, which absorbs radiation at the same wavelengths as NADH, and therefore interferes with the ability of the light to reach the NADH molecules. The haemoglobin also partially absorbs the NADH fluorescence. In particular, a reduction of haemoglobin in blood circulation causes an increase in fluorescence, generating a false indication of the true oxidation reduction state of the organ. U.S. Pat. No. 4,449,535 teaches, as means to compensate for this artifact, the monitoring of the concentration of red blood cells, by illuminating at a red wavelength (805 nm) simultaneously and in the same spot as the UV radiation required for NADH excitation and measuring the variation in intensity of the reflected red radiation, as well as the fluorescence at 440–480 nm, the former being representative of the intra-tissue concentration of red blood cells. Similarly Kobayashi et al (Kobayashi S., Nishiki K., Kaede K., Ogata E. J. Appl. Physiol. 31, 93–96, 1971) used ultraviolet (UV) illumination at 366 nm for NADH excitation, and red light at 720 nm for reflection measurements. However, U.S. Pat. No. 4,449,535 has at least two major drawbacks; firstly, and as acknowledged therein, using a single optical fiber to illuminate the organ, as well as to receive emissions therefrom causes interference between the outgoing and incoming signals, and certain solutions with different degrees of effectiveness are proposed. More importantly, though, two different wavelengths are used for illuminating the organ. FIG. 2 (based on Eggert & Blazek, 1987, © the Congress of Neurological Surgeons, Lippincott Williams & Wilkins) illustrates the penetration depth profile for various tissues of the human brain as a function of illuminating radiation wavelength, showing a plateau of relative insensitivity, of penetration depth (PD) with wavelength, for a wavelength range between about 360 nm and about 440 nm. For illuminating wavelengths greater than 440 nm, the penetration depth increases sharply with wavelength. Similar characteristics are found with other organs of the body. Thus, as may be seen from FIG. 2, the use of light radiation at the red end of the spectrum in accordance with U.S. Pat. No. 4,449,535 or as proposed by Kobayashi, to correct for blood haemodynamic artifacts in the NADH signal introduces inaccuracies into the measurements due to differences in penetration depths and therefore in the actual sampling volumes. Even though both radiation wavelengths are incident on the same spot, since detection is also at the same point, effectively two different elements of tissue, volume are being probed since the different radiation wavelengths penetrate the tissue to different depths. This results in measurements that are incompatible one with the other, the blood volume measurement relating to a greater depth of tissue than the NADH measurement. Therefore, the device disclosed by this reference does not enable adequate compensation of NADH to be effected using the simultaneous, though inappropriate, blood volume measurement. There is in fact no recognition of this problem, much less so any disclosure or suggestion of how to solve it. Further, there is no indication of how to measure other parameters such as blood flow rate or blood oxygenation level using the claimed apparatus.
In earlier patents; U.S. Pat. Nos. 5,916,171 and 5,685,313 (which have a common inventor with the present invention), a device is described that enables the monitoring of microcirculatory blood flow (MBF), the mitochondrial redox state (NADH fluorescence) and the microcirculatory blood volume (MBV), using a single source multi-detector electro-optical, fiber-optic probe device for monitoring various tissue characteristics to assess tissue vitality. During monitoring, the device is attached to the fore-mentioned tissue. The probe/tissue configuration enables front-face fluorometry/photometry. The two most important parameters involved in that fiber arrangement are the Optical Penetration Depth (PD) and the Averaged Sample Depth (SD), the PD parameter being dependent on both the tissue-type and on the irradiation wavelength; the SD parameter being dependent on the PD parameter and the distance between the ends of the excitation and collection fiber in contact with tissue.
Although U.S. Pat. No. 5,916,171 and U.S. Pat. No. 5,685,313 represent an improvement over the prior art, they nevertheless have some drawbacks:                (i)The oxidation level of the blood will introduce artifacts, affecting both the Mitochrondrial Redox State measurement (NADH fluorescence) and the microcirculatory blood volume (MBV) since these patents do not specify how to compensate for the oxygenation state of the blood in the tissue, i.e., the relative quantities of oxygenated blood to deoxygenated blood in the tissue. This problem is substantially overcome in the present invention by performing the NADH and blood volume measurements at an isosbestic point of the oxyhaemoglobin deoxyhaemoglobin absorption spectrum.        (ii)There is no facility included for measurement of the oxyhaemoglobin—deoxyhaemoglobin level, i.e. the Blood Oxygenation State, which is also an important tissue viability parameter, worthy of monitoring.        (iii) In these two U.S. patents, the same tissue volume needs to be monitored for all parameters, and the same light source and wavelength is used for the illumination needed for monitoring all three parameters. To measure both the NADH level and the blood flow rate, a relatively powerful UV laser is used. Using a relatively high intensity UV laser illumination source as proposed raises safety issues, especially for long-term monitoring.        (iv) The blood flow measurements impose several requirements on the UV laser source. In particular, the UV laser should have a high coherence length and very low intensity optical noise. Such lasers at these wavelengths are also not standard components and are indeed quite difficult to come by, which might lead to supply problems.        (v) There is no suggestion of monitoring Fp level, with or without any of the other parameters.
It is an aim of the present invention to overcome the above deficiencies in the prior art.
Particularly, it is an aim of the present invention to provide a method and apparatus enabling the simultaneous in-vivo monitoring of blood flow rate (i.e. intravascular mean velocity times the number of moving red blood cells) and at least one, and preferably all, of the following: NADH concentration by fluorescence, total blood volume (i.e. concentration of red blood corpuscles) by reflectometry, blood haemoglobin oxygenation (i.e. the oxy/deoxy haemoglobin ratio) by fluorescence, flavoprotein concentration by fluorescence; for the same body tissue, in substantially the same layer within the same region. These parameters, which represent different biochemical and physiological activities of the tissue, are used to assess the tissue vitality in said layer and tissue region.
It is another aim of the invention to provide flexibility in design of apparatus for simultaneous measurement of four or five different parameters with reference to the same tissue layer.
It is another objective of the present invention to provide a method and apparatus for enabling the blood oxygenation of a tissue to be measured, which overcomes the deficiencies of the prior art.
It is another aim of the present invention to provide a method and apparatus for enabling the blood oxygenation of a tissue to be measured where prior art absorption methods cannot be used.
It is a further aim of this invention to enable the concurrent monitoring of blood parameters in different regions of the same organ.
It is a further aim of this invention to enable the concurrent monitoring of blood parameters in the same or different region of a number of different organs of the same type, for example the kidney of a number of patients.
It is a further aim of this invention to enable the concurrent monitoring of blood parameters in different organs belonging to the same or different patients.
Other objects and advantages of the invention will become apparent as the description proceeds.
These and other objectives are realised by the present invention by a revolutionary approach to tissue viability measurement, directed at a common tissue layer concept rather than based on necessarily using the same excitation wavelength for all parameters. The same tissue layer measurements can be achieved, as explained further on, by-utilizing several wavelengths that are all confined within a well defined wave-band, or alternatively by using even very different wavelengths and making adequate compensation for variable penetration depths, rather than being restricted to using a single radiation illumination as taught by U.S. Pat. No. 5,916,171 and U.S. Pat. No. 5,685,313.
Thus, the NADH fluorescence, blood volume and blood haemoglobin oxygenation state are measured using the same monochromatic illumination wavelength and the same detection fibers, ensuring that the same tissue volume is monitored for these three blood parameters. The illumination point is not coincident with the detection point, and the spacing between these points may be chosen according to the average sample depth that is desired.
The wavelength of the monochromatic light is chosen to lie at one of the isosbestic points of the extinction coefficient vs. wavelength curves for oxyhaemoglobin and deoxyhaemoglobin; wherein the NADH or blood volume measurements will be substantially unaffected by the oxygenation state of the blood.
The blood flow rate may be measured by Laser Doppler Flowmetry (LDF), typically using coherent light (a laser radiation), the illumination being applied at the same point on the tissue as for the above three parameters. Furthermore, this laser radiation can also be used for excitation of Fp fluorescence which enables the monitoring of flavoprotein concentration, which is an important physiological parameter, as discussed above.
However, the location of the detection fibers with respect to the illumination fibers, specifically the distance between their ends, is set to a different value to compensate for the different penetration depth of the two illuminating wavelengths, and thus to ensure that the same layer of tissue is monitored for the blood flow parameter and flavoprotein fluorescence, as is monitored for the other blood and tissue parameters. This distance will vary; both as a function of the tissue type being monitored and as a function of the selected wavelengths of the two illuminations. While it is generally preferable to monitor NADH and LDF over exactly the same tissue volume, not just layer, to achieve this aim, the excitation wavelengths used for the parameters being monitored should be confined within predefined wave-band for which penetration depth is substantially insensitive to wavelength.
Nonetheless, for any given type of tissue, there exists in general, a range of wavelengths with substantially the same penetration depth for each tissue type. For example, as illustrated in FIG. 2 for brain tissues, this plateau in penetration depth as a function of wavelength, extends from about 360 nm to about 440 nm, with some indication from other sources, that the plateau extends to even lower wavelengths. Similarly some other tissues feature similar plateaus at these or other wavelengths. If the monitored tissue is radiated using different wavelengths over the appropriate range, the penetration depth will be similar, and substantially the same volume of tissue may be monitored. In such cases, the same detection fibers may be used for both illuminating wavelengths.
Thus, the present invention also provides a method and apparatus for the measurement of blood oxygenation level based on fluorescence measurements, rather than reflection measurements. Essentially, a single radiation at a particular wavelength illuminates a tissue such as to stimulate the emission of fluorescence by the tissue. The intensity of the fluorescent radiation at two or more wavelengths (within the fluorescent radiation band) is measured, and the level of oxygenation is derived from these measurements. Such a method and apparatus is advantageously incorporated within the apparatus of the invention in which a number of tissue viability parameters are determined. Alternatively, a stand-alone device and corresponding method may be provided for the measurement of blood oxygenation level.
As discussed above, U.S. Pat. No. 5,916,171 and U.S. Pat. No. 5,685,313 are directed at the use of a single radiation at a single wavelength for monitoring a number of tissue viability parameters, including blood flow rate and NADH level. On the other hand, EP 442011 describes a sensor for non-invasive measurement of a single parameter, oxygen saturation in a tissue. In one embodiment, shown in FIG. 2 thereof, a carrier means has mounted therein a single light transmitter emitting electromagnetic waves of different wavelengths, and two receivers at different distances from the transmitter, each receiver being sensitive to a different one of these wavelengths reflected from the tissue.
Returning, to the references U.S. Pat. No. 5,916,171 and U.S. Pat. No. 5,685,313, a single optical fiber guide carries the single illuminating radiation to the tissue and receives light from the tissue via another fiber, and the received light is then directed into two separate channels. A single illuminating radiation is used to ensure that the same tissue volume is being considered for all the tissue vitality parameter measurements. Thus, not only would there be no motivation for a man of the art to consider these documents when desiring to provide an apparatus with two illuminating radiations at different wavelengths, these references actually teach against using more than one illuminating radiation source, and more so at different illuminating wavelengths. On the other hand, EP 422011 is directed exclusively at the measurement of a single parameter, oxygen saturation in a tissue, and does not consider in any shape or form the measurement of multiple tissue viability parameters such as blood flow rate and NADH—in fact it is not concerned with the measurement of two or more parameters, but rather uses both receivers to measure a single parameter. Thus, there would be no motivation for a man of the art to combine EP 442011 with U.S. Pat. No. 5,916,171 or U.S. Pat. No. 5,685,313 when seeking to provide a device according to the present invention. Moreover, even if the sensor of EP 442011 were to be combined with the apparatus of U.S. Pat. 5,916,171 or U.S. Pat. No. 5,685,313, the combination would not yield the present invention. For example, the apparatus of U.S. Pat. No. 5,916,171 and U.S. Pat. No. 5,685,313 does not provide radiation at a range of wavelengths, and the radiation is provided directly from a remote radiation source via optical fiber. This enables a relatively small tissue area to be monitored as the cross-section of the probe can therefore be quite small. On the other hand the sensor of EP 442011 has the transmitter itself (in the form of an LED) mounted onto the carrier, which therefore needs to be large enough to accommodate the same, and which has power leads, rather than optical fibers connecting the carrier to an external power source. Thus, these two devices—the apparatus and the sensor—are not compatible with each other, and very significant modifications to the two would be required to enable the sensor of EP 422011 to be incorporated into the apparatus of U.S. Pat. No. 5,916,171 and U.S. Pat. No. 5,685,313. This still leaves the question of how to configure the combination so that each of the receivers of EP 422011 is coupled to a different measuring channel of the apparatus of U.S. Pat. No. 5,916,171 and U.S. Pat. No. 5,685,313. More importantly, though, the sensor of EP 422011 is characterised in that the two receivers are mounted on the carrier in distances selected such that the lengths of the light paths through the tissue at the two different wavelengths are substantially equal. In such a case, by definition, the two different wavelengths must be directed to two different tissue layers, not to mention entirely different tissue volumes. Thus, not only would the fact that different tissue volumes are targeted by EP 422011 teach away from considering this reference in combination with U.S. Pat. No. 5,916,171 and U.S. Pat. No. 5,685,313 in the first place, such a combination still does not provide the apparatus of the present invention in which a single tissue layer is targeted by both radiations. In the present invention, the relative location of the detection fibers with respect to the illumination fibers, specifically the distance between their ends, is set to such as to compensate for the different penetration depths of the two illuminating wavelengths, and thus to ensure that the same layer of tissue is monitored for the blood flow parameter, as is monitored for the other blood and tissue parameters. Clearly, far from providing this arrangement, EP 422011 teaches away therefrom.
Regarding the determination of oxygenation level of a tissue according to the present invention, such a method and corresponding device are not disclosed or suggested in the prior art.
For example, WO 99/02956 uses a laser induced fluorescence method for assessing the levels of ischemia and hypoxia in a tissue, rather than blood oxygenation level. The method comprises the steps of (a) measuring the fluorescence spectra at two different points on the tissue; (b) calculating the tissue absorption spectrum from these measurements; and (c) calculating the intrinsic fluorescence spectrum. Thus, in order to perform the calculations for determining the absorption spectra, two different points on the tissue need to be considered, and thus the device requires two different detectors coupled to two corresponding measurement channels, in contrast to the present invention in which a single point on the tissue suffices for obtaining fluorescence measurements therefrom, which are in the form of intensity measurements. Further, there is no disclosure or suggestion of using the intensity of the fluorescent radiating at two or more wavelengths for determining ischemia or hypoxia, and less so for determining blood oxygenation level.
In U.S. Pat. No. 5,318,022 and in WO 98/44839, oximetry techniques are described, wherein in each case an excitation source of several wavelengths is used, and the intensity of the reflected radiation for each wavelength is measured, wherein the appropriate ratios of oxygen saturation are determined. In contrast, the present invention uses only a single wavelength, and the intensity of the fluorescent radiation emitted as a result thereof is measured at two or more fluorescent wavelengths, from which blood oxygenation level is determined.

Apparatus and method for monitoring tissue vitality parameters


An array substrate for a transflective liquid crystal display device is disclosed. The array substrate includes a substrate; a plurality of scanning lines and data lines on the substrate, crossing each other to define a plurality of pixel regions; a transmissive electrode disposed in the transmission region; and a reflector disposed in the reflection region and not subjected to a voltage. A lateral field is generated in the reflection region. The transflective LCD of the present invention achieves the maximum light efficiency in both reflection and transmission modes.

1. Field of the Invention
The present invention relates to transflective liquid crystal displays, and more particularly to single cell gap type transflective liquid crystal displays.
2. Description of the Prior Art
Liquid crystal display (LCD) types are divided into three kinds: a transmissive LCD, a reflective LCD, and a transflective LCD. However, the transmissive LCD is a non-effective light converter that merely transmits about 3% to 8% of light from the backlight. Therefore, the transmissive LCD requires a backlight device having high brightness, leading to high power consumption. The reflective LCD uses ambient light for imaging, thus saving power consumption. However, the reflective LCD can be used during the day or in environments where external light exists, but not during the night or under poor ambient lighting.
Therefore, the transflective LCD has been introduced. In general, two main approaches of transflective LCD have been developed: single cell gap (FIG. 1a) and double cell gap (FIG. 1b). FIG. 1a is a cross-section of a conventional transflective liquid crystal display using a single cell gap. The transflective LCD includes upper and lower substrates 200 and 100 opposing each other, and a liquid crystal layer 300 interposed between the upper and lower substrates. A common electrode 220 is formed below the upper substrate 200, a transmissive electrode 140 is formed in the transmission region T, and a reflective electrode 120 is formed in the reflection region R. The cell gap (d) in T and R regions is the same.
Light efficiency is proportional to the total retardation change experienced by the incident light traveling in the liquid crystal layer of the device. The total retardation change is a product of 1) birefringence change, Δn, 'seen' by the incident light as a result of the reorientation of the liquid crystal molecules upon an applied voltage and 2) total path length traveled by the incident light in the liquid crystal layer.
Since the light passes the LC layer 300 twice in the R region, but only once in the T region, the reflected light R experiences a total retardation change of (Δn)×(2d), twice that of T which is (Δn)×d. FIG. 1b shows that R reaches 100% brightness at 2.75V whereas T only reaches 50% at the same voltage.
In order to achieve high light efficiency for both R and T modes, the double cell gap approach is often used such that the cell gap in the R region is reduced to d/2, so that the total length traveled by light in the LC layer 300 for T and R regions is the same (FIG. 2a). The total retardation change in the R region, which is (Δn)×2×(d/2), is thus equal to that in the T region ((Δn)×d). Thus, both R and T can have equally high efficiency of 100% as shown in FIG. 2b. This approach, however, leads to much more complicated structure. The fabrication process needs to maintain good control over the difference between the two cell gaps, which depends on the control of the extra layer (usually an organic layer). Moreover, this difference in cell gap between R and T regions also leads to different response times between R and T modes.
U.S. Patent Publication US2003/0202139A1 discloses a transflective liquid crystal display that requires only a single cell gap. The disclosure in this publication is rather unclear. The abstract of this publication states that instead of reducing the cell gap of the reflective region, it reduces the birefringence change Δn of reflective pixels so that the total retardation change Δnd of the reflective region is equal to that of the transmissive pixels. This is realized by a partial switching of the pixels of approximately 45 degrees which occurs in the reflective pixel region of the single cell gap by applying fringing fields, generated by a discontinuous electrode, to the molecules in the reflective pixel region of the cell gap. It appears that the entire reflective region is provided with a discontinuous electrode in the structure disclosed in this publication. It is unclear how commercially viable would be the disclosed structure.


Device write operations may be controlled by receiving a request to perform a write operation to a device and determining whether the device is activated or inactivated. If the device activated, the device may be accessed to perform the requested write operation. If the device is inactivated, the write operation may be buffered to physical memory. Device read operations may be controlled by receiving a request from a process to read a portion of a file from a device and determining whether a limited power condition exists. If a limited power condition does not exist, the device is accessed to read the requested file portion into memory. If a limited power condition exists, the device is accessed to read a superset (either the entire file or less than the entire file) of the requested file portion into memory.

The present application describes systems and techniques for regulating access to file system devices in a computer system, for example, a mobile computing platform such as a laptop computer or a hand-held computer.
A typical laptop computer includes one or more file system devices through which files such as application files, data files, operating system files, and the like can be accessed—for example, written or read. Such file system devices include non-volatile data storage devices such as disk drives (e.g., hard disk, floppy disk, zip drive, CD or DVD drive, or non-volatile memory components such as flash cards) as well as other devices such as network interface adapters, or any other network access devices, which typically do not themselves store data but rather serve as a conduit through which file write and/or read requests are communicated to a data storage resource on a network.
Many users rely on their mobile computers for performing computing tasks, for example, running application programs such as word processors, spread-sheet programs, graphic presentation programs and the like, in the absence of the wall-socket AC power sources that are present in virtually all offices and homes. Consequently, a mobile user by necessity often relies on battery power for operating his or her mobile computer. Many users discover, however, that the battery life of their mobile computer is less than they would optimally desire. A mobile user on a long-distance flight may, for example, experience a lapse in battery life, and thus be forced to cease using the computer, while only half-way through the flight. This may be particularly true if the user is operating devices in the mobile computer such as disk drives, which typically exhibit a relatively high level of power consumption compared to other devices in the system.
In an effort to extend battery lifetime, several computer and/or operating system manufactures have developed utilities that enable users to regulate the behavior of their mobile computers while operating under battery power. These utilities can control properties such as screen brightness levels and the length of a hard drive time-out period—that is, the time duration of hard drive inactivity that may occur before the hard drive is forced to power down or otherwise assume a reduced power state.
In addition to the manufacturer-specific implementations of power saving utilities, various organizations have published specifications relating to power management. For example, Intel Corp. and Microsoft Corp. jointly published a power management specification entitled "Advanced Power Management (APM): BIOS Interface Specification," Rev. 1.2, February 1996. Another specification, "Advanced Configuration and Power Interface Specification," Rev. 2.0, Jul. 27, 2000, was published jointly by Compaq Computer Corp., Intel Corp., Microsoft Corp., Phoenix Technologies Ltd. and Toshiba Corp.
Details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims.


A two-wheel battery-powered vehicle having a platform, two wheels connected to the platform, a battery-powered wheel drive driving the two wheels, an attachment connected to the platform, and a sensor device arranged in the platform. A person standing on the platform and engaging the attachment moves the platform into an angle position corresponding to a body position of the person. Based on the angle position of the platform relative to a horizontal position, the sensor device controls the wheel drive such that the wheel drive, by acceleration or deceleration, keeps the vehicle and the person standing on the platform in a balanced position. The attachment has a leg support device for at least one leg of the person standing on the platform in order to keep the platform at a desired angle position. The leg support device is adjustable.

The invention generally relates to a two-wheel battery-powered vehicle comprising a platform, two wheels connected to the platform, a battery-powered wheel drive driving the two wheels, an attachment connected to the platform, a sensor device arranged in the platform, wherein a person standing on the platform and engaging the attachment moves the platform into an angle position corresponding to a body position of the person, wherein, based on the angle position of the platform relative to a horizontal position, the sensor device controls the wheel drive such that the wheel drive, by acceleration or deceleration, keeps the vehicle and the person standing on the platform in a balanced position.
Such a vehicle is in use and known under the name "Segway®". The platform of this known vehicle comprises a flat box in which the battery, the sensors, and the control equipment are arranged. The standing surface is positioned at the comfortable height of a usual stair step. The person steps from the rear onto the platform and reaches for two handles that, similar to a bicycle handlebar, are arranged on a column arranged on the platform. In one embodiment of the vehicle, one side of the handlebar contains a rotary handle with which the control right/left steering is achieved. In another, right/left steering is achieved by leaning the entire handlebar to right and left. Speed control is achieved by a special type of balance control: The more the person and the column supporting the handles leans forward, the faster the vehicle moves forward. When leaning to the rear, the vehicle moves backwards, or decelerates. When the vehicle stands still and the person is not moving, the balance is maintained by acceleration and counter acceleration in which the vehicle moves continuously back and forth within small fractions of a second.
The "Segway®" vehicle is subject to U.S. Pat. Nos. 5,701,965; 5,971,091; 6,302,230; 6,367,817; 6,408,240; 6,561,294; 6,575,539; 6,581,714; 6,598,941; 6,651,766; 6,779,621; 6,789,640; 6,796396; 6,799,649; 6,815,919; and 6,827,163 which are incorporated herein by reference. While the "Segway®" vehicle provided simple transportation, controlling such a vehicle while carrying objects, especially while operating a camera, is not well supported.
EP 1695896 and U.S. Pat. No. 7,303,132 describe a further development of the two-wheel battery-powered vehicle. Instead of the handles of the "Segway®" vehicle, an attachment that has a leg support device for at least one leg of the person standing on the platform for keeping the platform at a desired angle position is connected to the platform. To drive the vehicle, the person standing on the platform leans his body forwards or backwards, thereby engaging the attachment and inclining the platform. Based on the angle of inclination of the platform, the sensor device controls the wheel drive such that, by acceleration or deceleration, the vehicle and the person standing on it are kept in a balanced position. A right/left control equipment providing foot pedals controls turning of the vehicle in a traveling direction by driving the wheels at different speeds. The vehicle requires that the person leans, tilts or otherwise compromises the body in order to maneuver the transport.
Furthermore the above mentioned patents disclose a bow-shaped support, which is provided for an object to be carried on the vehicle; the support is arranged to be pivotable to the front and to the rear of the vehicle, preferably on or near the wheel axle, and can be connected to the body, preferably by a bracket laterally engaging the body. The support that extends approximately to the waist of the person is provided as a hard mount of a camera.
While the developments disclosed in EP 1695896 and U.S. Pat. No. 7,303,132 improve the possibilities to use the two-wheel battery-powered vehicle, several shortfalls when operating remain. For example, the vehicle shows a leg-saddle comprising two concave control shells placed between a user's legs at a height above the knees. With this vehicle braking requires a person to incline the body rearwards from above the knees, in particular from above the hips, which leads to unnatural body positions.
Furthermore the vehicle is vulnerable to accidents and mishaps. A common accident occurs when one or both wheels of the vehicle run into an object too high for the vehicle to negotiate, e.g. a wall, kerb, leg, or any other obstacle. This often results in the vehicle attempting to climb the object, thus throwing the person off the machine, and causing the vehicle to perform an emergency shut down, whereby it looses power and falls over. A person that does not carry or operate any equipment may be injured, but a person who does may also be forced to abandon the equipment, causing damage to it or to people or objects in the vicinity.


Novel tellurium compounds of the present invention have the formula: EQU TeR.sup.1 R.sup.2. wherein R.sup.1 is a fluorinated alkyl having the formula C.sub.n F.sub.(2n+1)-x H.sub.x where n may range from 1 to 6 and x may range from 0 to 2n, and R.sup.2 is selected from the group consisting of alkyls having 2 to 6 carbon atoms, cycloalkyls having 3 to 6 carbon atoms, allyl, alkyl-substituted allyl having 4 to 6 carbon atoms, cyclopentadienyl, benzyl, alpha-methylbenzyl, and bis(alpha-methyl)benzyl. The novel tellurium reagents are useful as sources for organometallic vapor deposition processes, particularly the MOCVD fabrication of II-VI semiconductor materials such as Hg.sub.x Cd.sub.1-x Te. The compounds are synthesized by high yield ligand exchange reactions between Te(R.sup.1).sub.2 and Te(R.sup.2).sub.2.

Semiconductor materials of the Group II-VI elements and especially those containing mercury, cadmium, and tellurium are useful as photodetectors for infrared radiation. Applications include heat sensors in automobile engines, solar cells, sensors for road obstacles, and infrared detectors for night vision and heat-seeking missiles.
In order to take advantage of the electronic properties for the II-VI materials, devices based on heterojunction diodes and superlattices must be fabricated. Device fabrication requires the ability to grow abrupt junctions over large areas but this has been hampered by the high temperatures required to grow tellurium containing alloys. The high growth temperatures coupled with low growth rates result in diffusion of mercury across the heterojunction, thus destroying its integrity and usefulness.
The apparent solution is to lower the growth temperatures and increase the growth rates. Metalorganic chemical vapor deposition (MOCVD) is a technique well-suited to the deposition of II-VI semiconductors. MOCVD is commonly employed in the semiconductor, optical, and optoelectronic industries for doping or coating a suitable substrate. MOCVD essentially involves depositing a thin film of an element or compound onto a substrate such as silicon. The deposited films can be sources of doping impurities which are driven into the substrate or the films themselves can have different electrical or optical properties than the substrate. The properties of the film depend on the deposition conditions and the chemical identity of the deposited film. MOCVD has significant advantages in that the process is uniform and amenable to scale-up. New source reagents and growth techniques that permit junction fabrication at low temperatures are required.
MOCVD of tellurium containing alloys is limited by the availability of appropriate tellurium source reagents. The most important criteria for effective reagents in low temperature CVD of tellurium are:
1) volatility of the tellurium source reagent, PA1 2) efficient decomposition of the source reagent to elemental tellurium without incorporation of impurities into the product film, and PA1 3) chemical and elemental purity of the source reagent.
The ideal reagent for CVD of a metal or metalloid element would be characterized by high volatility (vapor pressure of .gtoreq.10 mm Hg at room temperature) and rapid low temperature decomposition to the elemental form (e.g., decomposition at temperatures of about 200.degree. C. versus temperatures approaching 500.degree. C., which are required for the presently available tellurium source reagents) with no codeposition of carbon or other contaminants into the film of the desired element. Dimethyl and diethyltellurium are currently utilized as source reagents for the CVD of tellurium and are commercially available. Neither of these reagents possesses labile Te-C bonds and both require high temperatures (>450.degree. C.) for successful deposition of tellurium containing alloys (Hoke, W. E.; Lemonias, P. J.; Korenstein, R., J. Mater. Res., 1988, 3, 329).
No currently available tellurium source reagents are optimum for the intended applications. New tellurium reagents with weaker tellurium-carbon bonds have been introduced since 1985 and are included in the table below. The newer reagents have secondary or tertiary alkyl or allyl substituents, since it has been reasoned that these substituents will lead to enhanced decomposition at lower temperatures. While improvement is seen in the decomposition temperature, volatility of the starting reagent is sacrificed.
______________________________________ Organotellurium Source Reagents Vapor Pressure Growth Temp. (.degree.C.) (mm/.degree.C.) ______________________________________ Dimethyltellurium 450 51/25 Diethytellurium 450 9.3/25 Diisopropyltellurium 390 5.6/30 Ditertbutyltellurium 320 4/40 Diallyltellurium (280) 3.5/45 Methyl(allyl)tellurium 290 8/30 2,5-dihydrotellurophene 250 -- Dimethylditellurium (250) 0.26/23 ______________________________________ Hoke, W. E.; Lemonias, P., Appl. Phys. Lett., 1985, 46, 398. Kisker, D. W.; Steigerwald, M. L.; Kometani, T. Y.; Jeffers, K. S., Appl. Phys. Lett., 1987, 50, 1681. Parsons, J. D.; Lichtmann, L. S.; J. Cryst. Growth 1988, 86, 222. Parsons, J. D.; Lichtmann, L. S.; J. Cryst. Growth, 1988, 86, 217.
Perfluoroalkyltellurium compounds represent a novel alternative to the materials currently in use, yet until now these reagents have not been studied under MOCVD conditions, nor in many cases even synthesized. The increased volatility for alkyl(perfluoroalkyl)tellurium compounds, without significant alteration of growth temperatures or film quality, renders these compounds potentially superior source reagents for MOCVD.
The absence of intermolecular forces in perfluoroalkyl compounds often leads to increased volatility. Boiling points for a number of main group alkyl compounds are compared with the corresponding perfluoro alkyl compounds below and demonstrate the trend toward lower boiling points for the fluorocarbon derivatives.
__________________________________________________________________________ Boiling Points of Selected Organometallic Compounds at 1 atm Compound (CH.sub.3).sub.2 S (CF.sub.3).sub.2 S (CH.sub.3).sub.2 Se (CF.sub.3).sub.2 Se (CH.sub.3).sub.2 Te (CF.sub.3).sub.2 Te __________________________________________________________________________ b.p. (.degree.C.) 37.3 -22 54.5 -- 82 23 __________________________________________________________________________ CRC Handbook of Chemistry and Physics 55th Ed. 1974-75; Herberg, S.; Naumann, D., Z. Anorg. Allg. Chem., 1982, 492, 95
A further concern that arises in MOCVD of tellurium-containing materials is the high toxicity of hydrogen telluride or the dialkyltellurium compounds. In addition, these materials possess odors that are so foul and persistent that they are exceedingly unpleasant and inconvenient to work with. The excursion of even extremely small amounts of the lower alkyl tellurides into the air creates an intolerable working environment. Thus new organometallic compounds of tellurium, with enhanced volatility and reduced toxicity and stench factors, would be desirable.

Organometallic tellurium compounds useful in chemical vapor deposition processes


A semiconductor sealing mold for sealing a semiconductor element within a thermosetting resin is provided with resin inflow openings formed in oppositely and substantially symmetrically opposed relation to the active surface and back surface of a lead frame connected semiconductor element. As a result, the application of the molding process and method of encapsulation of the semiconductor element can be accomplished under conditions of uniformly applied pressure to opposite surfaces of the semiconductor element and extending outwardly in all radial directions from the center of the semiconductor element. Furthermore, since the bonding wires and lead frame leads are substantially aligned in the same radial directions from the center of the semiconductor element, damage does not occur to these wires or leads during the molding process.

This invention relates generally to a semiconductor sealing mold and more particularly to a semiconductor sealing mold employed in a method of encapsulating a semiconductor element via a resin sealing process.
FIG. 2A is a plan view of a lead frame connected semiconductor element, and FIG. 2B is a sectional view along the line 2B--2B in FIG. 2A disclosing a semiconductor sealing mold 20 as known in the art. Semiconductor element 8 is secured to lead frame 1 via semiconductor element mount 6, such as, with an adhesive or eutectic alloy. The output pads of semiconductor element 8 and internal leads 2 of lead frame 1 are connected by a plurality of bonding wires 16 comprising fine metal wire, such as, gold or copper-aluminum. Further, a dam bar 3 is formed between internal leads 2 and external leads 4 of lead frame 1. Also, pilot holes 5 and outer frame 7 may be formed external of lead frame 1.
Previously employed semiconductor sealing molds have resin inflow openings 10 formed in a lower mold portion 14 so that they are only in communication with the side wall regions of lower mold cavity 12B. Semiconductor apparatus employed in connection with such semiconductor sealing molds require initial alignment of lead frame 1 between upper mold portion 13 and lower mold portion 14 of the semiconductor sealing mold, followed by heating these mold portions at a temperature between 160.degree. C. to 180.degree. C., and thereafter compressing lead frame 1 between mold portions 13 and 14 at a predetermined pressure. Then, a thermosetting resin having a low viscosity is introduced at resin inflow opening 10 and runner 11 to the interior of the compressed and heated mold portions 13 and 14 to bring about filling of the mold cavity 12. However, since resin inflow opening 10 is provided within the confines of lower mold portion 14 relative to lead frame 1, the thermosetting resin flowing into cavity 12 from resin inflow opening 10 is actually blocked by the presence of lead frame 11 so that lower mold cavity 12B will fill at a faster rate than upper mold cavity portion 12A. In other words, in the encapsulation of semiconductor element 8, the flow of resin in the mold cavity was directed towards semiconductor element from one direction only. In this manner, the resin forced into cavity 12 flows from lower mold cavity 12B into upper mold cavity 12A and, as a result, the force of the resin flow through and about lead frame 1 will shift semiconductor element mount 6 and internal leads 2 toward the upper reaches of upper mold cavity 12A. This approach in mold filling tends to damage semiconductor element 8 and/or its leads. For example, (1) The position of the semiconductor element 8 relative to lead frame 1 is deformed, disarranged or twisted. (2) Internal leads 2 of lead frame 1 are deformed. (3) Adjacently disposed bonded wires are brought into contact causing electrical shorts or the bonded wires are severed or broken. All of these problems result in significant deterioration or destruction of the useful life of the lead frame connected semiconductor element.
The present invention resolves these problems and has as an object of providing a semiconductor sealing mold that avoids or eliminates the foregoing problems.
It is another object of this invention is to provide a semiconductor method of encapsulation of a semiconductor element in resin that presents damage to the semiconductor connections to its lead frame during the sealing or encapsulation process.
It is a further object of this invention to provide means to increase the yield of lead frame connected semiconductor elements subjected to a semiconductor sealing mold process wherein they are encapsulated in a resin material.
It is another object of this invention to provide a semiconductor sealing mold to prevent the occurrence of fundamentally fatal defects in the employment of semiconductor sealing apparatus, such as, a distorted position change of the semiconductor element relative to its lead frame or mount, deformation of the lead frame internal leads, and undesirable electrical contact between adjoining bonding wires or the severing of bonding wires.


A portable urinal device is provided with an elongated body having a first section and a second section, the first section being releasable connected to the second section. The first section includes an open end coupled to the second section and a closed end having a top surface. A retractable flexible tube having a first end secured within the first section and a second end that is retractable away from the top surface is preferably disposed about a spindle located within the first section. The second end of the flexible tube is preferably disposed outside the first section. A device for creating suction at the first end of the retractable tube so as to draw fluid from the second end of the flexible tube to the first end of the flexible tube is coupled to the first end of the flexible tube. A motor is operatively engaged with the spindle to rotate the spindle and retract the flexible tube into the first section. First and second extension members adapted for coupling to second end of the flexible tube are preferably secured to the top surface of the first section.

Bladder control problems, sometimes called urinary incontinence, affect millions of Americans. There are three types of bladder control problems: overactive bladder; sphincter abnormalities (stress incontinence); and mixed incontinence (a combination of both overactive bladder and sphincter abnormalities). Urge incontinence can result in the need to use the restroom at times when there is no readily available facility. This immediate need to relieve oneself may lead create situations that, unsightly, dangerous and even unlawful. Those individuals who are not fortunate enough to make it to a convenient restroom must settle for other alternatives. These alternatives can range from urinating in an alley, on the side of the road and, in severe instances, involuntary wetting. These situations can be embarrassing, and can lead to fines or, in the case of public urination, even citation.
Several transportable urinal device have been patented that may address some of the above issues. For example, U.S. Pat. No. 3,703,731 is directed to a device that includes a housing enclosing a container for storing urine. A hose is coupled to the container and coiled within the housing. The house is provided with an applicator to collect urine from the user. In use, the hose is reeled out of the housing and the applicator is applied to the user. U.S. Pat. No. 4,631,061 is directed to still another urinal device. The xe2x80x2061 patent discloses a device comprising a hose coupled to a receptacle for storing urine. A collection vessel is attached an end of the hose to minimize urine leakage. A vacuum pump is provided for suctioning urine through the hose into the container.
A significant issue with the prior art urine collection devices is the design of the collection vessel. It is desirable to use separate collection vessels for male and female users. For convenience and flexibility, both the male and female collection vessels should be readily accessible to the user.
In addition, in many prior art systems, the hose is left to dangle after the user has finished urinating. This can cause leakage problems that may lead to unsanitary conditions.
A portable urinal device according to the invention includes an elongated body having a first section and a second section, the first section being releasable connected to the second section. The first section includes an open end coupled to the second section and a closed end having a top surface. A retractable flexible tube having a first end secured within the first section and a second end that is retractable away from the top surface is preferably disposed about a spindle located within the first section. The second end of the flexible tube is preferably disposed outside the first section. A device for creating suction at the first end of the retractable tube so as to draw fluid from the second end of the flexible tube to the first end of the flexible tube is coupled to the first end of the flexible tube. A motor is operatively engaged with the spindle to rotate the spindle and retract the flexible tube into the first section. First and second extension members adapted for coupling to second end of the flexible tube are preferably secured to the top surface of the first section.
The portable urinal device of the present invention will allow men and women a practical alternative to public restrooms even at the most inconvenient times. Whether one is stuck in traffic, on a long road trip, or even if one just doesn""t feel like using a public restroom. By coupling the extension members to the top surface of the device, the extension members are likely to be readily available wherever the device is found. Thus, men and women alike can comfortably use the device without fear of excessive leakage.


A navigation system including a present-position sensing system for sensing a present position; information storage medium for storing map information; an input device for entering into the system the destination, a roundabout point, a bypass, and the location desired to be traversed for entry of input indicating the execution of a route search from the present position sensed by the present-position sensing system to the destination; an output device for outputting information route guidance; and a central processing unit including a route searching capability for searching for a route to the destination; a route storage capability for provisionally storing the identified route; and route guidance control for sending a signal for performing route guidance to the output device. When the roundabout point or bypass is entered in the system, a search cost for roads and intersections near to the roundabout point or bypass is raised so that route search processing can be performed. When the location desired to be traversed is set, roads near to the location desired to be traversed are retrieved for search purposes. In travel guidance, a present-position mark is displayed in either a continuous mode or a blinking mode depending on the state of travel.

This invention relates to generally a vehicular navigation system for providing route guidance according to a set route and, more particularly, to a vehicular navigation system which includes an added function of setting a transit point using an expressway or toll road as a transversal road, so chat a road satisfying a transit point condition can be selected from a plurality of roads to provide guidance to a destination through a transit point set on the road or the selected road.
The navigation system for the vehicle searches for a route from the present position of the vehicle or a designated starting location to the destination based on entry of the location, such as the destination, and provides route guidance based on the route found, thereby providing the driver of the vehicle with information on a route to the destination when the vehicle is traveling on unfamiliar roads. To accomplish this, the vehicular navigation system has a function that enables a route from the present position to the destination be searched for based on entry of the destination, a present position sensing function for sensing the present position and direction of the vehicle, a guidance function for collating the detected present position with a guidance route to provide route guidance along the guidance route, and the like. The guidance function enables the guidance route found by the search processing to be displayed on a map or intersection map, for instance, and the present position and direction of travel of the vehicle to be displayed on the map or intersection map to thereby provide route guidance to the driver. In addition, some navigation systems have a function for providing a driver with information on an intersection at which the vehicle must make a turn, for instance, the remaining distance, its name, and whether turning to the right or left, a function for informing the driver of characteristic features to enable the driver to confirm the guidance route during travel, and a function for providing guidance in the form of not only screen displays but voice or sounds as well.
However, when the route is searched for only using entry of locations, such as the departure location and destination, a route is often found which includes locations the driver does not wish to pass through for reasons such as road conditions and environments or heavy traffic. In this case, processing for calculating another route in lieu of the found route may be envisaged. However, even when this processing is executed, the route found often includes a location the driver does not wish to pass through. Such processing may be performed until a route desired by the driver is found. However, this takes much time to find the desired route, and needs awkward operations because the route to the destination must be calculated a good many times.
Various modification are made to route guidance display screens so that for the confirmation of the present position and direction of travel of the vehicle on the guidance route, the driver can take a quick look at a guidance screen as if the driver were looking at meters. For instance, when the present position and direction of travel of the vehicle are displayed on a map, a guidance route on a map or the like is displayed such that the direction of travel can always turn upward or toward the top of the display. Alternatively, a guidance route on a map display can always be displayed with north at the top of the display, so that an arrow indicating the present position of the vehicle is pointed in the direction of travel. Still alternatively, a mark indicating the present position of the vehicle may blink at a given period so that it can be easily identified (see, for instance, JP-A-58-10708).
In a conventional system where a vehicle's present position mark is blinked, however, it is impossible to reduce an updating time length because the updating of the present position of the vehicle occurs in synchrony with the blinking period. This results in a problem that the distance the present position mark moves across a detailed map each blink is increased, especially when the speed of the vehicle becomes high.
FIGS. 1A-1C illustrates problems associated with the conventional system designed to blink the present position mark of the vehicle. Now consider the case where there are a set of successive intersections with the rearmost one being a guidance intersection at which the vehicle must make a turn, as shown in FIG. 1A. When a distance between adjacent intersections is short, it is impossible for the driver to have a precise indication of the present position of the vehicle in motion, when the present position mark of the vehicle is held, or blinked, off as shown in FIG. 1B. Thus, there is a strong possibility of failing to take notice of the intersection at which the vehicle must make a turn. In other words, it is possible that the driver will make a wrong turn at an intersection situated in front of the rearmost one, as shown in FIG. 1C, or pass straight through the intersection at which the vehicle must make a turn. In this case, the driver will take notice of, with surprise, the fact that the vehicle is off course only after the present position mark is displayed or blinked on. Thus, a grave problem with the present position mark blinking system is that it is difficult to achieve any real-time monitoring of the mark position being displayed.
In a system where a vehicle's present position mark is always displayed, or highlighted without blinking, on the contrary, there is a difficulty in looking at or for characters and marks on a map because they remain hidden by the mark. Moreover, due to no change in the screen being displayed, the user has difficulty noticing the fact that the system (computer) is constantly operating. Especially when the vehicle is at a stop, the screen being displayed is often taken as remaining looked.
Vehicular navigation system having a function for setting a transit point and providing guidance to the destination through the thus set transit point are disclosed in JP-A-2-3899, and JP-A-337216. Conventionally accepted methods for setting the destination include those for providing guidance to the destination via a route found on the basis of the entered destination, for providing guidance to the destination through a first destination via a route found using the destination as a second destination, and for setting a plurality of transit points scheduled to be traversed on a map, so that after the vehicle has passed through a give distance from one scheduled transit point, guidance can be provided to the next scheduled transit point. For instance, JP-A-4-220112 discloses a system for providing guidance to the final guidance point with respect to the set destination.
For destination setting input, one method is known, wherein repeated selection is made from an a list of institutions or facilities, such as, buildings, banks, parks, and playgrounds, to derive a registered destination pre-stored in a storage device to thereby set the registered destination as the destination. In another known method, a map having a center positioned at the location of a registered destination is further scrolled through to set a desired location as the destination.
The object of transit point input is to set a transversal road enabling the user to go to the destination through a selected road, to say nothing of setting the aforesaid transit point as the destination. Currently, it is possible to indiscriminately set the transit point on a drivable road or a nearest drivable road. When the transit point is indiscriminately set on an general road, however, it is impossible to set an expressway or municipal expressway as the transversal road. When a guidance point for the transversal point is indiscriminately set on the nearest general road, however, a problem may arise. For instance, when the transit point is set at a store or other transit point situated alongside an expressway or municipal expressway, route guidance onto the expressway or municipal expressway occurs.
Consider, for example, the case where the user sets the destination without recourse to data on registered locations (location data corresponding to telephone numbers, names of establishments or addresses, which have been stored in a storage device and are selected by the user for setting purposes). For instance, when a cursor is moved from pre-displayed map to set the position of the cursor as the destination, or when the data on registered locations is used to display a map having a center positioned at a location corresponding to the registered location, and a cursor is then moved to set a desired location as the destination, it is required to set a location at which a route search finishes, i.e., a final route guidance location, because the location to be set is often found on a drivable road. In the systems proposed in JP-A-4-220112 and JP-A-6-337216, a point on a road, i.e. one identified in the system, that is nearest to the destination, or transit point, is set as a guidance location, i.e., a final guidance point, or a point scheduled to be traversed, respectively. When the destination, or transit point, is set in this way, it is likely that a point on the road that is nearest to the entered destination, or transit point, is always set as a guidance point by reference to road data. As a result, some difficulty arises, that is, in a congested road area or the like, a guidance point is set on a road that is undesired by the user.


A multiple-layered tampon applicator that has at least one modification to one or more inner layers that form the applicator. As a result, enhanced aesthetics, enhanced functionality, or both are achieved in the applicator.

1. Field of the Invention
The present invention relates generally to a multiple-layered tampon applicator. More particularly, the present invention relates to a multiple-layered tampon applicator with a modified inner layer(s), which results in improved functionality and aesthetics.
2. Description of Related Art
There exist numerous applications that require a product to possess both highly functional properties in conjunction with highly aesthetic properties. This is especially true with consumer products, where the consumer is not only concerned with how well the particular product functions, but also how the product looks and feels.
In particular, feminine hygiene products, such as tampons, are subject to above-identified constraints, making it extremely difficult to make a product that is highly functional, yet meets the aesthetic demands of the consumer.
Through consumer studies, it has been determined that tampon applicator color, texture and finish can alter a user's perception of insertion ease and comfort of said applicator. This includes, but is not limited to, impartation of pigment, modification of surface texture, coefficient of friction, surface contact points, and visual effects due to reflection of light.
With regard to tampon applicators, it is widely known that they are generally formed from either a molded thermoplastic material, such as plastic, or a paper laminate, such as cardboard or paperboard.
Liquid coated paper laminate applicators are known in the art. For example, U.S. Pat. No. 4,412,833 to Weigner et al. is directed to an applicator formed of a high-gloss paper that can be coated with a degradable, dispersible or water soluble polymer, such as a modified polyethylene, polypropylene, polyvinylidene chloride or polyvinyl alcohol. U.S. Pat. No. 4,508,531 to Whitehead provides an applicator with a heat-sensitive coating, such as polyolefin (e.g., polyethylene or polypropylene) or a heat sensitive adhesive. U.S. Pat. No. 5,984,888 to Nielson et al. is directed to a paper applicator article having multiple paper layers and a compostable coating on the exterior surface.
However, neither the liquid nor film coatings applied to the prior art cardboard tampon applicators described above have permitted the combination of the formation of the desired glossy finish, retention of applicator circularity, reduction in friction, and sufficient biodegradability, let alone while further providing enhanced aesthetics to the applicator. Further, some prior art liquid coatings are more expensive, and require the use of organic solvents, leading to higher manufacturing cost and consumer cost.
The present invention overcomes the difficulties in providing additional aesthetic properties and/or additional functional properties to a tampon applicator without compromising the desired functional properties associated with the outer or exterior surface of the tampon applicator. This is accomplished by modifying at least one inner layer of material that forms the multiple-layer applicator. As a result, a highly functional product having enhanced aesthetics and or functionality is efficiently produced without compromising any of the desired functional properties associated with the exterior surface.

Cardboard tampon applicator with optical enhancing material coated on inner layers


One preferred embodiment of the present invention is directed to a convenient and efficient dispenser that includes at least one container and at least one nozzle for dispersing the contents of the container(s). In one preferred embodiment, first and second nozzles functionally associated with sterilization agent within the container are positioned to disperse the sterilization agent to first and second target points respectively, the first target point being distinct from the second target point. In another preferred embodiment of the present invention, a grid is positioned in front of the nozzle(s) so that a dispersement of sterilization agent from within the container(s) sterilizes the grid(s) when the nozzle(s) are activated. Yet another preferred embodiment of the present invention is directed to a multiple-mist dispenser that includes a dual chamber activation sleeve so that two nozzles are simultaneously actuable by depression of the dual chamber activation sleeve.

The present invention is directed to a convenient and efficient means for dispensing and more specifically to a multiple-mist dispenser for dispersing dispersement (such as a spray or mist) in a plurality of directions and/or having a net or wire grid in front of at least one dispersement nozzle.
Hand washing is extremely important to reduce the spread of germs, bacteria, and disease. Sometimes, however, soap and water are not readily available. In addition, regular washing with soap and water may irritate the skin. Several products on the market recognize this and attempt to provide alcohol-based hand sanitizers (both rinses and gels) as is discussed in the article, "Maximizing Hand-Hygiene Compliance to Improve Outcomes: A New Tool for Infection Control," published in the November 2001 issue of Infection Control Today at http://www.infectioncontroltoday.com/articles/1b1feat4.html.
There are also many patents directed to devices aimed at reducing the spread of germs, bacteria, and disease. U.S. Pat. No. 5,960,991 to Ophardt, for example, is directed to a fingerprint activated soap dispenser. U.S. Pat. No. 5,863,497 to Dirksing is directed to an electrostatic hand sanitizer. U.S. Pat. No. 5,808,553 to Cunningham is directed to an apparatus for enforcing hygiene. U.S. Pat. No. 5,074,322 to Jaw is directed to a structure of sterilizing hand dryer. U.S. Pat. No. 4,670,010 to Dragone is directed to a liquid-nebulizing device for the dermatological treatment of the hands. U.S. Pat. No. 3,220,424 to Nelson is directed to sanitizing equipment for sanitizing a person's hands. German Patent No. DE3604256 to Barsom is directed to a device for disinfecting, cleaning, and drying hands. The proliferation of devices emphasizes the need for an effective device for hand sterilization.
The best hand sanitizers and sterilization agents, however, do not work if the user promptly reinfects himself.
One example of a user reinfecting himself is when, after a thorough hand washing, a door with a contaminated handle must be opened. This usually occurs when a user washes his hands in the bathroom. Then, to leave the bathroom, he must open a door that has been handled by others who have not diligently sterilized their hands. This type of reinfection can sometimes be avoided by using a paper towel to open the door.
Another example of reinfection is when sterilized hands are used on a dirty "computer" controller such as a keyboard, mouse, button, touch screen, trackball, joystick, or other means for controlling a "computer." "Computer," for purposes of this disclosure, includes any controllable device, including, but not limited to, computers, games, copy machines, elevators, typewriters, adding machines, and any other device that can be controlled. Reinfection is extremely common when multiple people use a computer controller. This occurs when the "computer" is in public places such as libraries, public information kiosks, gaming facilities, stores, elevators, and other publicly accessible locations. This also occurs in offices where multiple people use the same workstation. Even a private controller may be contaminated by the user's own previous prior unsterilized usage. Once the user's sterilized hands touch the unsterilized controller, the user's hands become unsterilized.
Even the containers of the hand sanitizers can carry infections. If a user touches the container with unsterilized hands, the container becomes contaminated. The usual practice is for the user to pour hand sterilizer onto one hand. If the user puts down the container and rubs his hands together appropriately, he would have sterilized hands as long as he did not touch the unsterilized container again. The more likely scenario, however, is that he would sterilize one hand, touch the container, and then sterilize the other hand. This would leave the user with one unsterilized hand and, if the hands were brought together, possibly two unsterilized hands.
Some types of soap and hand sterilizers come in containers that are wall mounted. The user may actuate the wall-mounted devices, for example, by placing one hand under a spout and pressing a button with one or more fingers or thumb, placing his fingers under the spout and pushing a lever with the heel of his hand, or placing the palm of his hand under the spout and pulling forward with one or more of his fingers. These all require at least some contact with contaminated surfaces.
U.S. Pat. No. 5,785,250 to De Laforcade (the "De Laforcade reference") and U.S. Pat. No. 6,189,810 to Nerushai et al. (the "Nerushai reference") are directed to devices for spraying a liquid that has at least two nozzles. It should be noted, however, that the purpose of both of these devices is to provide a single and homogeneous spray. This is done by directing the sprays of the nozzles so that they at least partially overlap and/or join together. Such a configuration is not significantly functionally different from a single spray dispenser.


A plasma display apparatus and a method of driving the same are disclosed. The plasma display apparatus includes a plurality of scan electrodes, a plurality of data electrodes, a scan driver and a data driver. The scan driver scans the plurality of scan electrodes during an address period in one scanning type of a plurality of scanning types having different scanning orders. Further, the scan driver supplies a scan signal, of which the duration of a voltage rising period is different from the duration of a voltage falling period, to the scan electrodes when scanning the scan electrodes. The data driver supplies a data signal to the data electrodes depending on the scanning type selected from the plurality of scanning types.

1. Field of the Invention
This document relates to a display apparatus, and more particularly, to a plasma display apparatus and a method of driving the same.
2. Description of the Background Art
A plasma display panel comprises a front panel, a rear panel and barrier ribs formed between the front panel and the rear panel. The barrier ribs forms unit discharge cell or discharge cells. Each of discharge cells is filled with a main discharge gas such as neon (Ne), helium (He) and a mixture of Ne and He, and an inert gas containing a small amount of xenon (Xe). When it is discharged by a high frequency voltage, the inert gas generates vacuum ultra-violet rays, which thereby cause phosphors formed between the barrier ribs to emit light, thus displaying an image. Since the plasma display panel can be manufactured to be thin and light, it has attracted attention as a next generation display device.
A plurality of electrodes, for example, a scan electrode, a sustain electrode and a data electrode are formed in the plasma display panel. A driver supplies a predetermined driving voltage to the plurality of electrodes to generate a discharge such that an image is displayed. The driver for supplying the predetermined driving voltage to the plurality of electrodes of the plasma display panel is connected to the plurality of electrodes in the form of a driver integrated circuit (IC).
For example, a data driver IC is connected to the data electrode of the plasma display panel, and a scan driver IC is connected to the scan electrode of the plasma display panel.
When driving the plasma display panel, a displacement current flows in these driver ICs. A magnitude of the displacement current varies by various factors.
For example, a displacement current flowing in the data driver IC may vary in accordance with equivalence capacitance of the plasma display panel and the number of switching operation times of the data driver IC. More specifically, the displacement current flowing in the data driver IC is proportional to the equivalence capacitance of the plasma display panel and the number of switching operation times of the data driver IC.
In particular, when image data is a specific pattern where logical values 1 and 0 are repeatedly input, the displacement current flowing in the data driver IC excessively increases such that the data driver IC is electrically damaged.

Plasma display apparatus and method of driving the same


The present disclosure relates to using a coating to protect a portion of an optical fiber that is intended to buckle within a fiber optic connector. The fiber optic connector can include a bare fiber optical connector.

Fiber optic communication systems are becoming prevalent in part because service providers want to deliver high bandwidth communication capabilities (e.g., data and voice) to customers. Fiber optic communication systems employ a network of fiber optic cables to transmit large volumes of data and voice signals over relatively long distances. Optical fiber connectors are an important part of most fiber optic communication systems. Fiber optic connectors allow two optical fibers to be quickly optically connected without requiring a splice. Fiber optic connectors can be used to optically interconnect two lengths of optical fiber. Fiber optic connectors can also be used to interconnect lengths of optical fiber to passive and active equipment.
A typical fiber optic connector includes a ferrule assembly supported at a distal end of a connector housing. A spring is used to bias the ferrule assembly in a distal direction relative to the connector housing. The ferrule functions to support an end portion of at least one optical fiber (in the case of a multi-fiber ferrule, the ends of multiple fibers are supported). The ferrule has a distal end face at which a polished end of the optical fiber is located. When two fiber optic connectors are interconnected, the distal end faces of the ferrules abut one another and the ferrules are forced proximally relative to their respective connector housings against the bias of their respective springs. With the fiber optic connectors connected, their respective optical fibers are coaxially aligned such that the end faces of the optical fibers directly oppose one another. In this way, an optical signal can be transmitted from optical fiber to optical fiber through the aligned end faces of the optical fibers. For many fiber optic connector styles, alignment between two fiber optic connectors is provided through the use of an intermediate fiber optic adapter.
Another type of fiber optic connector can be referred to as a ferrule-less fiber optic connector. In a ferrule-less fiber optic connector, an end portion of an optical fiber corresponding to the ferrule-less fiber optic connector is not supported by a ferrule. Instead, the end portion of the optical fiber is a free end portion. Similar to the ferruled connectors described above, fiber optic adapters can be used to assist in optically coupling together two ferrule-less fiber optic connectors. Such fiber optic adapters can include specialized fiber alignment structures adapted to receive bare optical fibers. Example ferrule-less fiber optic connectors are disclosed by PCT Publication No. WO 2012/112344, PCT Publication No. WO 2013/117598, and U.S. Pat. No. 8,870,466.

Ferrule-less fiber optic connector with re-coat layer to protect buckling portion of optical fiber


The present invention provides a steering communication system being able to individually obtain a telemetry data from a steered-object communication devices mounted on the steered-object. An arbitrary identification number assigned to a plurality of steered-object communication devices mounted on a steered-object at the time of pairing-setup is associated with the equipment ID of a pairing object. When performing transmission request of a telemetry data, a steering signal adding the transmission request information and the own identification number is transmitted. The steered-object communication device judges signal classification of the inputted control signal. When the steering signal adding transmission request information and the own identification number is inputted, the steered-object communication device transmits a telemetry data signal adding the telemetry data as an answer signal to a steering communication device.

1. Technical Field
The present invention relates to a steering communication system used in a radio control steered-object such as various models, for example, a model helicopter, plane, car, and ship, and an industrial machine unmanned operated, in particular, the steering communication system communicating between a steering communication device steered by an operator and a plurality of steered-object communication device mounted on an steered-object. More specifically, the present invention relates to a steering communication device, a steered-object communication device and a steering communication system, which are able to obtain a telemetry data of various sensors mounted on the steered-object by request to send the telemetry data for each steered-object communication device.
2. Background of the Invention
In a model plane as a steered object radio-operated, a drive mechanism such as a servomotor or gyroscopic apparatus controlling a ladder, elevator, engine throttle, aileron and the like so as to steer the steered object is mounted. When an operator controls an operating stick at a transmitter end, a steering signal including steering data corresponding to the controlled amount is transmitted to the steered-object. When a receiver mounted on the steered-object receives the steering data, each drive mechanism is properly driven with the required amount, and the steered-object is steered according to the operation of the transmitter side from the operator.
Also, in a big or luxury model plane, the airframe price of the plane is very expensive. As a result, a dual receiving system mounting each one receiver in both wings is used in case of emergencies, such as a case that radio communication from the transmitter is interrupted and thereby the operator is not able to control. By using the above system, even if one receiver is not able to receive the signal normally, the other receiver is able to control, and thereby it is possible to maintain attitude control of the airframe and recover it. As an apparatus using for the above type of system, for example, the invention disclosed in PTL 1 is known.
Furthermore, in another embodiment different from the above dual receiving system, a system using for a diversity function is disclosed in PTL 2. The system has two receivers, and select and use a signal of one of the receivers received normally.    [PTL 1] Japanese Patent Publication No. H02-311100    [PTL 2] Japanese Patent Publication No. 2012-5121

Steering communication device, steered-object communication device and steering communication system


An Fe-Cr-Mn alloy is disclosed which has the following composition by wt% and corrosion resistance of which is improved and deterioration in its strength is prevented at grain boundaries due to irradiation of high-energy particles such as neutrons: 5 to 40% of Mn, 5 to 18% of Cr, 2.0 to 12% of Al and the balance of Fe except for unavoidable impurities. In the alloy according to the present invention, Al is added to an Fe-Cr-Mn alloy by a restricted quantity as a main component element. As a result of the addition of Al, an alloy can be obtained in which lowering of concentration of Cr at grain boundaries due to irradiation of high-energy particles such as neutrons can be prevented or concentration of the solutes can be raised.

1. Field of the Invention
The present invention relates to an Fe-Cr-Mn alloy for constituting a reactor for a nuclear fusion reactor, a fast breeder reactor, a light-water nuclear reactor or the like. More particularly, the present invention relates to an Fe-Cr-Mn alloy capable of satisfactorily preventing the lowering of concentration of chromium at grain boundaries when subjected to a neutron irradiation environment.
2. Prior Art
Hitherto, the Fe-Cr-Mn alloy, which has been developed as the material for use as the atomic reactor material, is constituted by substituting nickel with manganese, nickel being a main component of the Fe-Cr-Ni alloy, which had been widely employed as the steel for the light-water nuclear reactor or the fast breeder reactor. Furthermore, element compositional proportion of the alloy has been changed or minor elements have been added to the alloy for the purpose of securing the phase stability. Therefore, an advantage can be obtained in that residual radioactivity (to be called "induced radioactivity" hereinafter) of the radioactive isotope, formed by irradiation of neutrons having the energy spectrum generated due to fusion reaction, can be reduced. Therefore, safety of the nuclear fusion reactor can significantly be improved and an excellent economical advantage can be obtained in terms of facility of the maintenance of the reactor and efficiency of the waste disposal and re-utilization of reactor systems.
In Japanese Patent Unexamined Publication No. 61-9560, a conventional alloy is disclosed, which has fine austenitic structure and which is composed of 20 to 40 wt% of manganese, 0 to 15 wt% of chromium, 0.4 to 3.0 wt% of silicon, at least one of less than 0.7 wt% carbon and 0.3 wt% of nitrogen each of which quantity can stabilize fine austenitic structure, 0 to 0.1 wt% of phosphor, 0 to 0.01 wt% of boron, 0 to 3.0 wt% of aluminum, 0 to 0.5 wt% of nickel, 0 to 2.0 wt% of tungsten, 0 to 1.0 wt% of tantalum, 0 to 2.5 wt% of vanadium and the balance substantially composed of iron. High manganese austenitic steel having a same structure and improved high temperature strength is disclosed in Japanese Patent Unexamined Publication No. 62-238353, the high manganese austenitic steel being composed of, by weight, 0.05 to 0.5% of carbon, 12 to 50% of manganese, 2 to 20% of chromium, 0.1 to 5.0% of silicon, 0.01 to 4.0% of aluminum, 0.25% or less of nitrogen, one or more elements selected from a group consisting of 0.01 to 1.0% of titanium, 0.01 to 1.0% of niobium and 0.005 to 0.2% of zirconium by a predetermined proportion and the balance of iron except for unavoidable impurities. There is also a high manganese austenitic steel which is composed by adding at least one or more elements selected from a group consisting of 10% or less of nickel, 5% or less of cobalt and 10% or less of copper to the above-described high manganese austenitic steel. In addition, a high manganese austenitic steel of a different type is known which is composed by adding one or more elements selected from a group consisting of 5% or less of molybdenum and 5% or less of tungsten to the above-described high manganese austenitic steel. Furthermore, a high manganese austenitic steel is known which is composed by adding one or more elements selected from a group consisting of 10% or less of nickel, 5% or less of cobalt and 10% or less of copper and one or more elements selected from a group consisting of 5% or less of molybdenum and 5% or less of tungsten to the above-described high manganese austenitic steel.
However, the change in composition of the elements of the above-described alloys at grain boundaries which can take place when used under neutron irradiation environment has not been studied. In particular, the alloys have a problem of lowering of chromium concentration at grain boundaries which may cause deterioration in corrosion resistance and in strength.