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We investigated the role of potassium conductances in the nucleus of the solitary tract (NTS) in determining the efficacy of the baroreceptor and cardiopulmonary reflexes in anesthetized rats. The baroreceptor reflex was elicited with an intravenous injection of phenylephrine to evoke a reflex bradycardia, and the cardiopulmonary reflex was evoked with a right atrial injection of phenylbiguanide. Microinjection of two Ca-dependent potassium channel antagonists (apamin and charybdotoxin) into the NTS potentiated the baroreceptor reflex bradycardia. This may reflect the increased neuronal excitability observed previously in vitro with these blockers. In contrast, the Ca-dependent potassium channel antagonists attenuated the cardiopulmonary reflex, whereas voltage-dependent potassium channel antagonists (4-aminopyridine and dendrotoxin) attenuated both the baro- and cardiopulmonary reflexes when microinjected into the NTS. The possibility that the reflex attenuation observed indicates a predominant distribution of certain potassium channels on γ-aminobutyric acid interneurons is discussed.
- baroreceptor reflex
- cardiopulmonary reflex
- 4-aminopyridine
- dendrotoxin
- apamin
- nucleus of the solitary tract
it has been well documented that primary afferent fibers from cardiorespiratory receptors project to, and terminate in, the nucleus of the solitary tract (NTS) located within the dorsomedial medulla (for review, see Refs. 14 and 28). However, the neural mechanisms by which this afferent information is integrated within the NTS to produce reflex cardiovascular and respiratory responses are not fully understood. In this regard, we have hypothesized that the sensitivity of an NTS neuron to afferent input is dependent on its own specific set of intrinsic membrane properties and that modulation of one or more of these conductances in a population of such neurons would alter the magnitude of an evoked reflex response.
On the basis of previous in vitro recordings of NTS neurons (5,7-9, 16, 21) and recent simulation experiments (24), our current approach is to investigate the functional role of a variety of potassium conductances, including both voltage- and Ca-dependent (I K andI K Ca, respectively) channels, that control neuronal firing properties in regulating reflex sensitivity in vivo. Studies by Richter and co-workers (22) have also used in vivo approaches to demonstrate a functional role forI K Ca: intracellular injection of the calcium chelator BAPTA into postinspiratory neurons, which are responsible for switching off inspiration irreversibly, prolonged action potential discharge, and reduced adaptation. It was suggested that blockade of such channels in postinspiratory neurons could lead to a lengthening of the postinspiratory phase and a decrease in respiratory frequency (22). From in vitro studies on the NTS, twoI K Caconductances were identified (5, 8, 10) that were sensitive to either charybdotoxin [large-conductanceI K Caantagonist (BK); Ref. 16] or apamin [small-conductanceI K Caantagonist (SK); Ref. 21]. Additionally, voltage-dependent channels included both a transient potassium current (I A) and a delayed, more slowly inactivating potassium current (I D) that were both blocked by 4-aminopyridine (5, 8, 9, 16, 21). Another voltage-dependent potassium channel antagonist used in this study, dendrotoxin, has not previously been used on the NTS; although in cells isolated from the rat nodose ganglia this toxin had little effect onI A, with a much larger effect onI D (29, 30).
We have chosen to study two reflexes with contrasting roles in the intact animal: the baroreceptor reflex acts on a beat-by-beat basis to maintain arterial pressure in a regulatory manner around a given set point; in contrast, the cardiopulmonary reflex, which can be elicited experimentally with a right atrial injection of phenylbiguanide, has been postulated to act in a defensive way (6) to protect, for example, against a rise in pulmonary interstitial pressure during exercise (19). Despite a qualitatively similar pattern of reflex response [i.e., falls in arterial pressure, heart rate (HR), and respiratory frequency], the cardiopulmonary reflex is quantitatively more potent than its regulatory counterpart. In this regard, it has recently been shown, using both extra- and intracellular recording techniques, that there is very little convergence of baroreceptor and pulmonary C fiber synaptic inputs onto NTS neurons in both the mouse (20) and cat (27). One might conclude, therefore, that these reflexes are mediated by two separate populations of NTS neurons with distinct intrinsic membrane properties. Moreover, a differential distribution of potassium conductances could underlie the contrasting potency of these two reflexes.
Because in vitro studies (16, 21) revealed that blockade of potassium currents (either voltage- or Ca-dependent) increased the responsiveness of the neuron during depolarizing current injection, one might anticipate that blockade of eitherI K orI K Ca in NTS would increase reflex efficacy. However, we show that in the in vivo rat blockade ofI K Cacounterintuitively attenuates the cardiopulmonary reflex, whereas blockade of I Kattenuates both this and the baroreceptor reflex.
Surgical Procedures
Experiments were carried out on mature male Sprague-Dawley rats (220–270 g; n = 54) in which anesthesia was induced with a mixture of α-chloralose-urethan-pentobarbitone sodium (69, 690, 30 mg/kg ip, respectively) and supplemented with 3–8 mg intravenous α-chloralose when required, as judged from the withdrawal of a hindlimb to a paw pinch.
The trachea was intubated below the larynx, and the left femoral artery and vein were cannulated for recording arterial pressure (Gould Stratham) and subsequent injections of anesthetic, respectively. The left jugular vein was cannulated for administration of phenylephrine. Phenylbiguanide was injected into the right atrium via a cannula inserted into the right jugular vein. Rectal temperature was monitored and maintained at 37.5 ± 0.5°C. Animals were placed in a stereotaxic head holder (Kopf Instruments) and ventilated artificially using humidified oxygen-enriched air. End-tidal CO2 was sampled and monitored and maintained at 4.5 ± 5% by altering tidal volume. The dorsal medulla was exposed by retraction of the nuchal muscles and removal of the dura. When necessary, the posterior cerebellar vermis was retracted to expose the dorsal surface of the medulla.
Recording Procedures
The electrocardiogram (ECG) was recorded via stainless steel pins placed subcutaneously in a fore- and hindlimb, and the right phrenic nerve activity (PNA) was recorded using a bipolar hook electrode. Both signals were amplified (Neurolog module 104) and filtered (Neurolog module 125). Recordings of arterial pressure, HR, and rectified and integrated PNA were relayed to a CED 1401 interface (Cambridge Electronics Design), displayed on a computer monitor, and stored digitally (CED; Spike2).
Microinjection Techniques
Seven-barreled glass microelectrodes were used with the tips cut back to 35–40 μm to allow pressure injection. Microinjection volumes were 45 nl, calculated by observing the distance the meniscus moved down the glass capillary using a binocular microscope fitted with an eye piece graticule. Microelectrodes were placed (under visual guidance of a binocular microscope) into two anatomically distinct regions of the NTS using reference landmarks on the medullary surface, such as area postrema and calamus scriptorius. From preliminary mapping studies our histological data revealed that microinjection sites that were selective in altering the magnitude of the baroreceptor reflex were located ∼200 μm caudal to obex (the point at which the central canal opens into the fourth ventricle), 600 μm lateral to midline, and 500 μm ventral to the dorsal surface. In contrast, sites that were selective in altering the efficacy of the cardiopulmonary reflex were located ∼900 μm caudal to obex, 100 μm lateral to the midline, and 400 μm ventral to the dorsal surface. At the end of the experiment, Pontamine sky blue (2%) was microinjected and the brain stem was excised from the skull and fixed with a solution containing 2% paraformaldehyde and 20% sucrose. Transverse sections were cut (100 μm) on a freezing microtome, mounted on subbed slides, stained with neutral red, and placed under a coverslip. The microinjection sites were reconstructed with reference to obex and the solitary tract and documented on standard outlines (taken from Ref. 2).
Experimental Protocol
The baroreceptor reflex was evoked by an intravenous injection of the α1-adrenergic receptor agonist phenylephrine (PE; 40 μg/ml; 1–3 μg bolus) to raise arterial pressure and induce a reflex bradycardia. The cardiopulmonary reflex was elicited by a right atrial injection of phenylbiguanide (PBG; 100 μg/ml; 1–10 μg bolus ), a 5-hydroxytryptamine 3 agonist (5-HT3), used to stimulate J receptors located within the lungs (19). Both drugs were prewarmed to 38°C. At the end of some experiments, the position of the tip of the cannula was checked to be within, or very close to, the right atrium. Because all microinjections were unilateral, in some experiments the pulmonary vagal C fiber afferent input was restricted to one side of the NTS by cutting the vagus nerve contralateral to the microinjection site; however, even with both vagi intact it was possible to modulate the efficacy of the cardiopulmonary reflex with unilateral microinjections. After at least three successive and consistent control reflex responses, a potassium channel antagonist was microinjected into the NTS. Two minutes later this was followed by an intravenous injection of either PBG or PE (depending on the reflex studied); these injections continued every 10 min until recovery was obtained. To test microinjection site specificity in some experiments both reflexes were elicited in quick succession after microinjection into the NTS. Control microinjections of artificial cerebrospinal fluid were made using similar volumes (45 nl).
The peak magnitude of the reflex falls in HR and mean arterial pressure (MAP), as well as the changes in inspiratory duration and frequency of PNA, was compared before and after a microinjection of a potassium channel antagonist, and the differences were statistically tested (paired Student's t-test). To ascertain that measurements of the baroreceptor reflex bradycardia were on the linear part of the sensitivity curve, multiple measurements of MAP and the corresponding HR fall, were made during the rising phase of PE-induced pressor responses. Moreover, the gain of the reflex [expressed as fall in HR (beats/min) per mmHg rise in MAP] together with the rate of rise of the pressor response (mmHg/s) was calculated for each PE injection. Data are presented as means ± SE.
The microelectrodes were filled with Pontamine sky blue (2%) and artificial cerebrospinal fluid (aCSF; constituents as in Ref. 21) along with a selection of the following chemicals dissolved in aCSF: 4-aminopyridine (4-AP; 2 mM; Sigma), dendrotoxin (DTX; 10 μM; Alamone), apamin (100 μM; Alamone), and charybdotoxin (ChTX; 5 μM; Alamone). PBG (Sigma) and PE (Sigma) were dissolved in 0.9% NaCl at concentrations of 100 and 40 μg/ml, respectively.
In 54 animals, the resting MAP was 96 ± 2 mmHg, and the resting HR was 465 ± 6 beats/min. Analysis of integrated PNA revealed a respiratory cycle length of 1.26 ± 0.08 s and a burst duration of 0.47 ± 0.03 s (n = 30). Microinjection of bothI K andI K Caantagonists resulted in transient falls in MAP from baseline: apamin 13 ± 5 mmHg (n = 11;P < 0.01), ChTX 25 ± 5 mmHg (n = 13;P < 0.001), 4-AP 12 ± 2 mmHg (n = 20;P < 0.001), DTX 9 ± 3 mmHg (n = 19;P < 0.01; Fig.1 A). Only theI K Caantagonists produced a significant (Fig.1 B) reduction in HR: apamin 13 ± 5 beats/min (P < 0.05), ChTX 18 ± 6 beats/min (P < 0.01). None of the antagonists had a consistent effect on either respiratory cycle length or phrenic burst duration. There were no significant differences in these cardiovascular responses between the rostral and caudal microinjection sites (seemethods). During reflex testing after a microinjection the basal levels of MAP, HR, and PNA were not significantly different from control values (Tables1 and 2). The effects of the antagonist on the evoked reflex usually occurred within 2 min after the microinjection and usually recovered within 80 min (Tables 1 and 2). Vehicle injection of aCSF (45 nl) had no effect, either on baseline cardiorespiratory variables or on reflex responsiveness.
Baroreceptor Reflex
The baroreceptor reflex was elicited via an intravenous injection of PE, which increased arterial pressure and induced a reflex bradycardia. As seen in Fig.2 B, measurements were taken on the linear portion of the baroreceptor reflex response curve. A 1- to 3-μg bolus of PE raised MAP by 73 ± 3 mmHg, which elicited a reflex bradycardia of 92 ± 10 beats/min (n = 25). Microinjection of potassium channel antagonists had no effect on the slight respiratory slowing observed during the induced pressor responses under control conditions or on the amplitude or burst duration of the PNA. In all experiments microinjections into the NTS had no significant effect on either the magnitude or the rate of rise of the PE-induced pressor response (Table 1). All effective microinjection sites were restricted to regions 100–200 μm caudal to obex as described inmethods (see above and Fig. 7).
Effect of blockade of IK Ca . Microinjection of either apamin or ChTX into the NTS potentiated the baroreceptor reflex (Table 1; Fig. 2); apamin increased the reflex bradycardia from 12 ± 3 to 25 ± 5% (n = 6;P < 0.05) and ChTX from 12 ± 2 to 24 ± 5% (Table 1; n = 6;P < 0.05).
Effect of blockade of IK . In contrast to apamin and ChTX, 4-AP attenuated the baroreceptor reflex bradycardia, reducing it from 23 ± 3 to 13 ± 2% (n = 8;P < 0.01; Table 1; Fig.3). Similar effects were observed with DTX: the evoked bradycardia was reduced from 32 ± 5 to 17 ± 6% (Table 1; n = 6;P < 0.01).
Site specificity of antagonists into NTS. In 14 of these experiments, as soon as the PE-induced increase in arterial pressure had returned to control (i.e., ∼5 min after a microinjection) the cardiopulmonary reflex was evoked with a right atrial injection of PBG. In 12 of 14 animals, the reflex was of similar magnitude to controls (i.e., that seen before microinjections into NTS). For example, microinjection of apamin into a site that was 0.1 mm caudal to obex (see Fig. 7) potentiated the baroreceptor reflex bradycardia from 5 to 30% but left the PBG-evoked bradycardia of 82% unaffected.
Cardiopulmonary Reflex
Right atrial injection of PBG elicited a 227 ± 14 beats/min decrease in HR and a 32 ± 2 mmHg decrease in MAP (n = 43) together with an increase in phrenic cycle length to 2.38 ± 0.38 s (n = 17). The doses used resulted in reproducible, submaximal effects with a latency of 1 to 1.5 s. This is within the pulmonary circulation time of the rat, indicating a relatively specific action of PBG on pulmonary vagal C fibers. All effective microinjections were restricted to more caudal regions of the NTS (i.e., 900–1,000 μm caudal to the obex; seemethods and Fig. 7).
Effect of blockade of IK Ca . Blockade of apamin- and ChTX-sensitiveI K Ca in NTS neurons attenuated the cardiopulmonary reflex (Table 2; Figs.4 and 6). After a microinjection of apamin into the NTS the reflex falls in HR and MAP were reduced from 63 ± 11 to 21 ± 3% (P < 0.01) and from 35 ± 3 to 23 ± 3% (n = 5;P < 0.05), respectively. Moreover, the duration of the reflex prolongation in phrenic nerve cycle length was reduced by 46 ± 7% (n = 4;P < 0.05). In seven other animals, a microinjection of ChTX reduced the bradycardia from 54 ± 9 to 15 ± 2%, the depressor response from 44 ± 4 to 29 ± 2%, and the reflex increase in phrenic nerve cycle length by 34 ± 17% (n = 7;P < 0.05).
Effect of blockade of voltage-dependent K+channels. Both 4-AP and DTX microinjected into the NTS produced qualitatively similar attenuating effects to theI K Caantagonists (see above; Table 2; Figs. 5and 6). In 12 animals, a microinjection of 4-AP attenuated the bradycardia from 51 ± 6 to 20 ± 4% (P < 0.01) and the depressor response from 33 ± 3 to 18 ± 5% (P < 0.01) and reduced the duration of the reflex prolongation in phrenic nerve cycle length by 27 ± 9% (n = 6;P < 0.05; Fig. 5). Similarly DTX attenuated the bradycardia from 42 ± 5 to 19 ± 3% and the depressor response from 30 ± 3 to 17 ± 3% (n = 13;P < 0.01; Fig.6 A; PNA not recorded).
Site specificity of antagonists in NTS. In 10 of these experiments, as soon as the PBG-evoked falls in HR and arterial pressure had returned to control (i.e., ∼4 min after the microinjection), the baroreceptor reflex was elicited. In eight animals, the baroreceptor reflex gain was not affected by microinjections into these caudal regions (i.e., 900–1,000 μm caudal to obex; see Fig.7); for example, 2 min after ChTX was microinjected into a caudal NTS site, the PBG-evoked fall in HR was attenuated from 48 to 15% and the depressor response from 40 to 28%, whereas the baroreceptor reflex bradycardia was not substantially altered (7% before and 4% after ChTX microinjection). The effective microinjection sites for both the baroreceptor and cardiopulmonary reflexes are shown in Fig. 7.
As far as we know this is the first study to investigate the physiological significance ofI K andI K Ca in the NTS for cardiorespiratory reflex function. Blockade ofI K Capotentiated the baroreceptor reflex but attenuated the cardiopulmonary reflex, whereas antagonizingI K produced a qualitatively similar depression of both reflexes.
Specificity of the Microinjection Technique
The microinjection technique is a useful first approach for understanding the physiological significance of channels or receptors and is dependent on sufficient diffusion of injectate to produce a systems level response. As suggested previously (13, 18), this technique does, however, have numerous disadvantages, particularly concerning the degree of specificity. With the use of equations derived by Nicholson (18) it can be estimated that a microinjection of 50 nl will spread ∼550 μm; however, the "effective" spread may well be less because the drug concentration will decrease from its source, and, furthermore, in the intact animal, it will be removed by the circulation.
Specificity of Microinjection Sites in NTS
Our results indicate that the effective spread of drugs was within previously determined estimates (18), because we could demonstrate site specificity of drugs on either the baroreceptor reflex or the cardiopulmonary reflex after microinjections into anatomically distinct regions of the NTS (i.e., 100–200 μm and 900–1,000 μm caudal to the obex; see Fig. 7 andresults). Although baroreceptor and pulmonary C fiber afferent innervation of NTS partially overlap, anatomic evidence suggests that there is a difference in the density of labeling of these afferents within this nucleus. Studies in the rat (12) and rabbit (33) suggest that aortic nerve afferents project, in part, to the commissural NTS, a region that has been described as playing an integral role in the cardiopulmonary reflex (3); however, the density of this baroreceptor innervation, particularly in the very medial regions that we microinjected into, which contain high densities of pulmonary vagal afferents (see below; Ref. 3), is not as great as that seen at the level of the obex. Because the microinjection technique relies on recruiting sufficient neurons to effect a change at the systems level, this could account for the large degree of specificity for the cardiopulmonary reflex at the commissural level. Similarly, it has been demonstrated with the use of microinjections of cobalt chloride into NTS that the primary site of pulmonary C fiber afferent termination lies between 0.7 and 1.1 mm caudal to obex (3), a region that was effective in modulating the cardiopulmonary reflex but not the baroreceptor reflex, and which lies at least 0.5 mm caudal to the sites where we could modulate the baroreceptor reflex consistently. Moreover, recent electrophysiological studies in the mouse (20) and cat (27) suggest that NTS neurons, which are synaptically driven by pulmonary C fiber stimulation, receive little convergent input from baroreceptors.
Transient Effects of Potassium Channel Blockers on MAP and HR
All four potassium channel antagonists evoked transient falls in baseline MAP and HR (see results and Fig. 1), indicating that bothI K andI K Ca are "tonically" active in NTS in the anesthetized rat. These data in combination with our results showing changes in reflex performance suggest roles in both static as well as dynamic circulatory control.
Effects of IKCaAntagonists on the Baroreceptor Reflex
A microinjection of either apamin or ChTX into regions of the NTS slightly caudal to obex resulted in an increase in the magnitude of the baroreceptor-mediated reflex bradycardia. This might be explained by an increase in the excitability of primary afferent terminals or of NTS neurons after potassium channel blockade and is consistent with the effect of blockingI K Ca in NTS neurons recorded in vitro: both a reduction in the after-hyperpolarization and an increase in firing response to injected current was observed (16, 21). The absence of an effect of apamin on dissociated NTS neurons reported previously (16) might reflect1) that there is heterogeneity of NTS neurons mediating the baroreceptor reflex or2) that the neurons studied did not belong to the population of cells mediating the baroreceptor reflex or3) that these channels were lost during the enzymatic isolation procedure.
It is perhaps surprising that antagonism of SK channels with apamin and BK channels with charybdotoxin produced a similar potentiation of the baroreceptor reflex and an almost identical attenuation of the cardiopulmonary reflex. There is no a priori reason to expect that the distribution of these two channel types would be similar on a given neuron or indeed that their blockade would produce a quantitatively similar systems effect. The limitations of the present experiments do not permit further interpretation; a detailed cellular analysis investigating the relative distribution and density of the twoI K Caconductance types on characterized NTS neurons is required.
Anomalous Effects of Blocking K+ Channels on the Baroreceptor and Cardiopulmonary Reflexes
We found that ChTX and apamin, in contrast to their effects on the baroreceptor reflex, attenuated the cardiopulmonary reflex. Furthermore, we demonstrated that blockade ofI K also reduced both baro- and cardiopulmonary reflexes. One possible interpretation of these data is thatI K Ca andI K are predominantly located on inhibitory [e.g., γ-aminobutyric acid (GABA)] interneurons impinging on NTS cells mediating cardiorespiratory reflexes. In this regard, only 40% of dorsal NTS neurons at the level of, and caudal to, the area postrema recorded in vitro contained 4-AP-sensitive currents and 64% apamin-sensitive currents (21). Thus, after blockade of potassium channels in GABA interneurons, excitability would be expected to increase (e.g., Refs.7, 24), which would augment levels of tonic inhibitory drive thereby reducing reflex efficacy. This is supported by a previously published observation of ours (4): antagonism of GABAA receptors within the NTS using bicuculline led to an increase in the magnitude of the cardiopulmonary reflex bradycardia; moreover, a concomitant microinjection of DTX and bicuculline prevented the attenuating effect of DTX on the PBG-evoked bradycardia. It should be emphasized, however, that these data do not reveal whether this is the result of the summation of two dependent or mutually exclusive events. Interestingly, preliminary in vitro data from our laboratory indicate that 4-AP can both decrease the ongoing firing rate and the firing response to injected current of NTS neurons (Butcher and Paton, unpublished observations); the neuronal mechanisms responsible for these observations are unknown at present but may underlie the reduction in reflex performance seen in vivo.
The attenuating effects of potassium channel blockers on cardiorespiratory reflex control reported here are analogous to recent studies where activation of 5-HT3receptors within the NTS reduced the gain of baroreceptor, chemoreceptor, and cardiopulmonary reflexes (15, 25, 26). Because 5-HT3 receptors are known to mediate excitatory actions (23), it was suggested that the effects of 5-HT3 receptors were mediated via a local GABAergic system within the NTS (26). This was further supported by the finding that bicuculline prevented the inhibitory effect of 5-HT on the baroreceptor reflex (15). In this regard, >90% of 5-HT3 receptors expressing cells in the neocortex and hippocampus are GABAergic (17). By analogy, our data would predict that GABA-containing interneurons within the NTS contain high densities ofI K channels and those that control the cardiopulmonary reflex also have high numbers ofI K Caconductances.
The involvement of potassium channels on presynaptic membrane terminals must also be considered. It is possible that our microinjections of potassium channel antagonists caused a depolarization block of the peripheral afferent endings. Alternatively, potassium channels may exist on the terminals of local GABA-containing neurons (see above). There is substantial evidence supporting the presence ofI K in GABAergic terminals: in synaptosomal preparations both 4-AP (32) and DTX (34) have been shown to release GABA, whereas inhibitory neurotransmission was enhanced by DTX in pyramidal cells (11). To our knowledge there are no such reports detailing the existence ofI K Ca in presynaptic GABAergic terminals.
In conclusion, our data indicate thatI K andI K Ca play an important role in determining the efficacy of both the baroreceptor reflex and the cardiopulmonary reflex in vivo. The exact mechanism, whether pre- and/or postsynaptic, by which blockade of potassium channels in the NTS leads to a reduction in cardiorespiratory reflex efficacy requires further investigation at the cellular level. Nevertheless, on the basis of our data obtained with bicuculline (4) together with previous reports of enhanced GABA-mediated neurotransmission after potassium channel blockade, the notion that there is a predominance of potassium channels on GABAergic interneurons within the NTS is supported.
With the exception of studies on invertebrates such as aplysia (e.g., 31), the functional implications of potassium channel activity remain largely uninvestigated. Clearly though, these currents play a pivotal role in determining the excitability of neurons and, as such, are prime targets for regulation by neurotransmitters and second messengers. Indeed, such neuromodulation has been implicated in mechanisms of plasticity, such as learning and memory, and perhaps, by analogy, may prove important in the NTS for determining, for example, baroreceptor reflex set point. Potassium conductances may also account for more hard-wired mechanisms such as the differing potencies of the baroreceptor versus cardiopulmonary reflexes. Neurons receiving afferent input on a beat-by-beat basis from baroreceptors may have a higher density ofI K Caconductances, which are needed to dampen their activity. When these channels are blocked the neurons would fire action potentials at a higher frequency, accounting for the potentiation of reflex efficacy that we observed. In contrast, pulmonary C fibers discharge at very low frequencies at rest (0.3 Hz; Ref. 1), which may negate the need for a central adapting mechanism. Whether or not the firing behavior of NTS neurons dictates the type and density of potassium channel that is expressed is open for experimental investigation.
We thank Dr. S. Kasparov for helpful discussions during the course of these studies.
Address reprint requests to J. F. R. Paton.
The research was funded by the British Heart Foundation (BS/93003) and Royal Society (Grant 14349). J. W. Butcher holds a British Heart Foundation PhD Studentship (FS/94080).
- Copyright © 1998 the American Physiological Society


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text: It's 1977. Fifteen-year old Vinnie isn't having a good year. He's recovering from the worst case of galloping acne his dermatologist's ever seen. His girl moved to California without even saying good-bye. And the ink on his parents divorce papers is barely dry, when his mom announces that they're moving from Queens to Long Island. The silver lining in all this is that they move next door to Patsy - everyone's dream girl. Not that she'd ever notice him. But when Vinnie calls Patsy one night, it leads to a chain of anonymous midnight conversations.


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It's that time of year again. Employers scrolling through resumes, candidates polishing shoes and searching for the perfect suit because it's job search season in the world of higher education. With The Job Placement Exchange (TPE) rapidly approaching (March 18-22nd), employers will soon be traveling to New Orleans in search of the perfect individuals for their institution. Candidates will be arriving in hopes of landing an interview which will lead them to the perfect job.
As a candidate, there's probably some thoughts on what you can do to make yourself the best possible candidate for the positions in which you hold an interest. Here's some tips to make the most of you (and your potential employers time) at TPE.
1). Prior to the conference, do your research. Look through job postings, read school mission statements, list out what you want to accomplish with this position. Find your ideal description (even if it's out of your reach) and use that description as a checklist for experiences other positions will give you to get that point. Have your questions lined up and know what you need to do to setup an interview or apply for a position.
2). Once at the conference, attend the candidate orientation. This will help you to understand where you should be prior to your interviews, show you where candidate mailboxes are located, discuss the communication process with employers and cover a variety of other helpful topics.
3). If you're nervous about interviewing, look to see if mock interviews are available. These are hosted by individuals who often conduct interviews. At the very least, mock interviews will help you to get used to answer questions and provide some feedback on how to better conduct yourself during an interview.
4). Acknowledge that as a candidate, you might be interviewing at one table in the morning and the table right next to it in the afternoon. It's a job search conference, so schools will understand that you are interviewing with other institutions.
5). Be honest with employers. If you have an interview at 4:00 and another wants to schedule at 4:30, it's okay to tell the later institution that you might be a few minutes late because of a prior to interview. Employers will understand that you're trying to fit in as many interviews as possible and would rather know that you might be a little late than not showing up at all. Also, be honest in how you answer questions. Conversations can be overheard, so be sure to keep your responses consistent and honest.
6). Prepare to have tunnel vision. You'll be interviewing at one table and another interview will be occurring at the tables to your right and left. Be focused on the person in front of you. Ignore everything else that's going on around you.
7). Understand that during TPE, the interviews never truly end. Employers will be on the plane ride down, sharing the room next to you, at the restaurants in which you choose to eat, etc. Be aware of how you conduct yourself in all of these settings. Jokes that might be understood between friends might be misconstrued by people who don't know you. The same goes with employers. You might see people with whom you just interviewed, so employers know their behavior is being watched by candidates as well. This is a time to observe the social interactions of a school and see if that's the right environment for you.
8). Constantly check your box for communication. Employers might try to schedule a last minute interview, so you want to try to respond as soon as possible.
9). Rejection is okay. If an employer offers an interview for position you're not interested in, it's alright to turn them down. Just be professional in your response. It's better to turn them down than to waste their time for that interview slot. It can also rob another candidate of an opportunity to interview for that position. If an employer sends you the "Thanks, but no thanks", don't let it get you down. Schedule another interview and move on through the process.
10). Don't forget the "thank-you's". You're going to need to take A LOT of thank you cards with you to the conference. As soon as an interview ends, wright out your thank-you card and have it placed in the employer's box.
After the conference, it's not time to sit back and relax just yet. Many employers might still want to do a phone interview. Some might use TPE as their initial interview and lead straight into on-campus interviews. Most important, don't get too stressed out about the job search process. The perfect job is there, sometimes it just takes a little longer than expected. You won't be unemployed for forever if you keep on trying.
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Productivity Effects of Foreign Acquisitions in Swedish Manufacturing: The FDI Productivity Issue Revisited
This study analyzes the difference between foreign and domestic ownership of firms with respect to productivity. Recent literature has shown that it is important to study the counter-factual outcome, i.e. what would the outcome be had the domestic firm never been acquired? The analysis is based on a panel of Swedish firm level data. In order to isolate the casual effects due to a takeover a propensity score matching estimator is applied to compare similar treated and untreated firms. The difference-in-difference estimations show that there is a positive effect of foreign acquisition on productivity. Foreign acquisitions increase the productivity in the acquired Swedish firms by between 3 and 11% depending on the estimator chosen. Moreover, this productivity difference does not occur immediately but starts between 1-5 years post acquisition.
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Volume (Year): 14 (2007)
Issue (Month): 2 ()
Pages: 241-260
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This text is aimed at a one-term course taken by allied health and agricultural science students. It includes annotated reaction summary tables, solved in-chapter examples, integrated applications (industrial, medical, etc.) and essays that describe organic chemistry's impact on the economy, environment, and the quality of life.
"synopsis" may belong to another edition of this title.
Francis A. Carey is a native of Pennsylvania, educated in the public schools of Philadelphia, at Drexel University (B.S. in chemistry, 1959), and at Penn State (Ph.D. 1963). Following postdoctoral work at Harvard and military service, he was appointed to the chemistry faculty of the University of Virginia in 1966. Prior to retiring in 2000, he regularly taught the two-semester lecture courses in general chemistry and organic chemistry. With his students, Professor Carey has published over forty research papers in synthetic and mechanistic organic chemistry. In addition to this text, he is coauthor (with Robert C. Atkins) of Organic Chemistry: A Brief Course and (with Richard J. Sundberg) of Advanced Organic Chemistry, a two-volume treatment designed for graduate students and advanced undergraduates. He was a member of the Committee of Examiners of The Graduate Record Examination in Chemistry from 1993-2000. Frank and his wife Jill, who is a teacher/director of a preschool and a church organist, are the parents of Andy, Bob, and Bill and the grandparents of Riyad and Ava.
"About this title" may belong to another edition of this title.
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Book Description McGraw-Hill Science/Engineerin, 2001. Paperback. Book Condition: New. Never used!. Bookseller Inventory # P110072319445
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Book Description Blacklick, Ohio, U.S.A.: McGraw-Hill Science Engineering, 2001. Soft cover. Book Condition: New. 3rd Edition. New, International Edition ,3rd Edition . Premium quality books. Ship via FedEx, UPS, DHL. Delivery time is 3-5 biz days. Bookseller Inventory # 0072319445
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- Andrew K Birnie, Shelton E Hendricks, Adam S Smith, Ross Milam, Jeffrey A French
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Exposure to androgens during prenatal development shapes both physiological and behavioral developmental trajectories. Notably, in rhesus macaques, prenatal androgen exposure has been shown to increase rough-and-tumble play, a prominent behavioral feature in males during the juvenile period in primates. While macaques are an Old World, polygamous species… (More)
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The effect of a nutritionally complete liquid-formula diet without soy polysaccharide or with the fiber source at 20, 30, or 40 g/d on mineral retention in young men was examined. Addition of 20 g soy polysaccharide to the liquid formula significantly (p less than 0.05) improved the retentions of copper, iron, zinc, and magnesium over the diet without added… (More)
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Supplier Homepage Product PPGI Others PPGI Hot DIP Galvanized Iron Coils for Roofing Sheets
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A:Yes, we could do SGS, CIQ, based on cutomers require.


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FAQs - Family Float
Family Float - US$30For the not so adventurous or the not so tall, why not spend your time drifting down the River Nile. Beautiful islands, birdlife and low grade rapids make it the ideal short family outing for both young and old.
|When is the best time of year to go rafting?
|Apart from Xmas Day and New Years Day we raft everyday as the flow is dam controlled and not seasonal or affected by rains.
|Do I need to book this trip in advance?
|The rafting is very flexible, however to ensure our service to you is as efficient as we like, we would recommend that you book at least the day before particularly if you require transport or accommodation. Please be aware that on weekends, especially in high season our accommodation can fill very quickly.
|Will I get wet and/or cold?
|You will certainly get wet but the water is always warm. You might get cold if it gets windy, in which case spray jackets will be provided.
|What happens if it is raining?
|We raft everyday rain or shine. As we are on the equator most rains in Uganda are tropical rains, intense but for only a short period of time. Should you encounter a storm in the morning we may delay the start until it has passed.
|What is the possibility of falling out of the boat?
|There is a chance you may fall out of the boat, though unlikely. You may swim voluntarily in the pools and our safety kayakers will always be close by.
|What is a safety kayaker?
|A safety kayaker will fetch you if you do fall out of the raft. They are there for your safety, because they are quicker and easier to manoeuvre than a raft.
|What if I am vegetarian or have other dietary needs?
|No problem, we cater for vegetarians every day but your trip leader will confirm numbers of anyone with special dietary needs at the briefing on the morning of rafting.
|What if I can't see without my glasses?
|If you have disposable contact lenses then we recommend you wear them, otherwise your glasses need to be securely tied to your head and helmet, however you take them at your own risk.
|Can I go if I have a medical condition?
|Please let us know in the morning if you have any medical condition you think we should be aware of particularly previous injuries, and take any medicines with you for the day.
|Can I go if I have a disability?
|We like to help everyone experience the Nile and specialize in helping those with disabilities. If you do have a disability and would like to go rafting please contact us and we will do our best to make it possible.
|What do I do with my valuables to keep them safe?
|Valuables can be left at our office at check in, or at the Adventure Centre at Explorers River Camp, they will be given a security tag and stored in a safe place. Do not take any valuables on the river!
|What about my bags?
|If you are staying at our River Camp your bags will be transferred while you are on the river. If you are not staying at our River Camp, we recommend you take a small bag with something dry to change into at the end of your trip, this will be kept in our office and meet you at the finish point. Any other bags will be tagged and remain in our office for collection there.
|What about crocs and hippos?
|In 15 years of operation there have been no crocodile related incidents as they do not like populated areas so are rarely seen. There are no hippos on this stretch of river.


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'Avatar' Actor Returning for Sequels
Wochit Headline News - Friday, 13 October 2017 (1 week ago)
Actor Giovanni Ribisi, who appeared in the first 'Avatar' movie, will reportedly return for the film's upcoming four sequels. Even though his role as RDA administrator Parker Selfridge from the first film wasn't a huge one, it's likely the multiple sequels will see his character fleshed out substantially. While there's no word yet on the plot for the first sequel, it should be interesting to see how Selfridge factors into it given the rebellion from the first 'Avatar'. The film's sequel is currently scheduled to hit theatres on December 18, 2020.


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Accidents at School
Every care is taken to make sure that children are properly attended to in the event of an accident. Minor accidents, cuts, and bruises are treated by staff members who are first aid trained. Where a student sustains a serious injury they will be attended to in a professional manner and parents contacted in accordance with the gravity and urgency of the situation. Any bumps to the head are treated and the parents are contacted. The school will, in extreme circumstances, ring directly for an ambulance whether the parents can be contacted or not, and then make contact with a parent. Where children are involved, we prefer to err on the side of caution. A record is maintained of all children who are treated in Sick Bay with a full accident report being completed for the more serious accidents.


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[Funeral Program for Alfred Ball, May 18, 1998]
Description: Funeral program for Minister Alfred Ball, born October 25, 1917 and died May 12, 1998. The funeral was held Monday, May 18, 1998 at Dellcrest Church of Christ. Funeral arrangements were made through Sutton-Sutton Mortuary and he was buried in Fort Sam Houston National Cemetery near San Antonio, Texas.
Date: May 18, 1998
Item Type: Refine your search to only Pamphlet
Partner: San Antonio Public Library


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21 Reasons Why You Should Appreciate Your Dog More!
July 16, 2017 | 7 Comments » | Topics: Dogs, Life
1. Remember that your puppy's main goal is to ensure you're happy, so remember to be thankful for that !
2. You will have a friend for life!
3. S/he's always up for a cuddle on the couch!
4. They put up with you, when they really don't have to.
5. Their loyalty is unmatched.
6. No matter how you're feeling, they will bring a smile to your face when you see them.
7. S/he doesn't understand the concept of privacy.
8. Remember when you're gone, there's not a second that goes by when they aren't thinking about you.
9. You may not be guaranteed a greeting from your human family when you come back home, but your faithful companion will always be there.
10. Looking at their face will make difficult times that much easier.
11. You won't ever have to wait on anyone because you will always have this reliable playmate.
12. Or s/he can be your snuggle buddy.
13. S/he's your reliable travel buddy.
14 And your driving assistant.
15. Celebrations with them are memorable.
16. They will be there with through the good times…and the bad.
17. Waking up to a face like this is always nice.
18. Going to sleep is much better when you have something to snuggle up to.
19. They give the best kisses!
20. A dog's love is unconditional, always.
21. They love you for who you are, no matter how old you get.
7 Responses to "21 Reasons Why You Should Appreciate Your Dog More!"
Kaley Says:
December 23rd, 2016 at 1:55 am
There's a secret about your post. ICTTTBIHYKY
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February 14th, 2017 at 10:42 am
With regard to to the Wretched Hive of Scum and Villainy at New York, my previous proposal: to wit, that we hotwire USS Intrepid, joyride it around a little, then anchor off Turtle Bay and use the catapults to fire old toilets through the windows at the UN……is herewith reintroduced.
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April 23rd, 2017 at 1:09 pm
Very interesting topic. I think I will dive into this a little deeper on my own. I have done meditation that focused on the third eye and can now put myself in a state of meditation where very little breathing takes place and the mind opens. I am still very amateur in this practice but I can feel my third eye tingling and opening at will on a regular basis now. I need to learn more to utilize this wonderful potential. Great post!
Utsav Srinet Says:
May 1st, 2017 at 2:48 am
The best dog I ever had was an enormous Great Dane, called Nicolas and he lived to the ripe old age of 12 years. It is all in the way you feed and handle them. The large breeds are not meant to be treated the same as little dogs, their bodies work differently. However, great post. Thanks for sharing !!
coin generator for pixel gun 3d Says:
May 8th, 2017 at 9:35 am
Well, Morocco's not the Middle East; it's North Africa. And this "vacation" is just a long weekend. The big one– posts coming soon– will be Bhutan in June.I later joined SDS but in 1964 I was completely clueless about the Vietnam War. It wasn't until freshman orientation that I started to figure out what was going on. Fortunately I was a fast learner… despite the pot. Or maybe it helped!


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Our Common Future is an open world community striving to further develop our democracies by introducing new participatory mechanisms. We foster social cohesion and intercultural dialogue through community actions, open journalism, and the creation of world policy communities.
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Check out our projects and get in touch!


text: PE Firms Fundraising: Brightstar, Kainos and Others Published March 04 2016, 11:18am EST More in Financial services Business services Print Email Reprints Share Share on Subscribe Now Complete access to real-time information and analysis of news and trends in the industry. Learn More 14-Day Free Trial No credit card required. Complete access to articles, breaking news and industry data. Get 14-Day Free Trial Have an account? Sign In


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Matthew 16:24–26 MSG Then Jesus went to work on his disciples. "Anyone who intends to come with me has to let me lead. You're not in the driver's seat; I am. Don't run from suffering; embrace it. Follow me and I'll show you how. Self-help is no help at all. Self-sacrifice is the way, my way, to finding yourself, your true self. What kind of deal is it to get everything you want but lose yourself? What could you ever trade your soul for?" Colossians 3:1-4 NLT Since you have been raised to new life with Christ, set your sights on the realities of heaven, where Christ sits in the place of honor at God's right hand. Think about the things of heaven, not the things of earth. For you died to this life, and your real life is hidden with Christ in God. And when Christ, who is your life, is revealed to the whole world, you will share in all his glory.
The Conclusion.
July 30, 2017 • John Scholtz


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Corsair H75 review -
Product Showcase
Product Gallery
Right then, as always the packaging and bundle first, everything is packaged and bundled safely in the box. Once unboxed you'll spot the liquid cooling unit consisting out of the radiator, fan, tubing, pump/cooling block. Most pre-fitted and ready to use of course. Next to that you'll spot a back plate that supports a wide variety of CPU sockets. AMD AM2, AMD AM3, AMD FM1, AMD FM2, Intel LGA 1155, Intel LGA 1156, Intel LGA 1366, Intel LGA 2011 based processors can be used in combination with this cooler as well as LGA 1150 (Haswell).
Included are:
- Corsair Hydro Series H75 Liquid CPU Cooler
- Mounting kit for all modern CPU sockets
- 2x SP120L High Performance Fans
- Fan and radiator mounting screws
- Thermal compound (pre-applied)
- Quick Start Guide
So summed up, once unboxed you'll spot the cooling unit consisting of the radiator assembly, fan and brackets + back plate that support a very wide range of AMD and Intel processors. A little thermal paste is actually already pre-applied on the cooler for you.
You'll receive a backplate and AMD retention clips. Pretty much any modern processor can be cooled with this kit. Installation is fairly easy, we'll show you that in this article as well.
Here we have the H75 unit, we'll need to mount the two variable PWM fans (120mm) ourselves and set them up in a push-pull configurations, pump, tubing and radiator are assembled as one single unit. Installation will be easy, 10 minutes tops.
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You can spend a lot of money on fans and everything RGB these days, but the one thing missing is that each component is regulated by a different piece of hard and software. Say no more, as Corsair jus...
Corsair GLAIVE RGB game mouse review
For the true gamers out there we now offer a review on the all new Corsair Gaming GLAIVE RGB game mouse, the device is sturdy and aesthetically pleasing with configurable RGB LEDs and has a grip that...
Corsair Vengeance RGB DDR4 memory review
In this article we review the new RGB series Vengeance DDR4 memory from Corsair. Not only do these puppies look awesome, they are properly specced as well. We received a 4x8GB DDR4 3000MHz CAS 15 DRA...


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Lassen College math program
Think about what career is best suited for you, and where you want to study. Request more information now.
Think about what career is best suited for you, and where you want to study. Request more information now.
Think about what career is best suited for you, and where you want to study. Request more information now.
Find info concerning Lassen College math program, and registering for elective discussion sections and seminars. Which college degrees give you the best chances of finding employment after graduation? There are a variety of engineering training programs that may appeal to you, such as mechanics, vehicle design, and alternative energy production. Concentrating on Lassen College math program, for example, you may gain an advantage in job recruiting on-campus. Check with the mathematics department for course registration deadlines, and math placement testing program requirements. Please use the form above to request admissions info for Lassen College.
While a math degree may not seem like a path to wealth at first glance, many fields are based almost entirely on a math foundation. For instance, both physics as well as engineering make use of algebraic formulas to determine motion and forces on objects, and the stress on materials. In business, financial accounting and stock investing count on the mathematical principle of compound interest over time. Math classes may be refocused toward practical applications, such as numerical analytics of big data online or statistical interpretation of scientific research results. Further, financial engineers or 'quants' may be called upon to prepare math-based reports for financial management, in order to develop high-speed, stock investment algorithms.
Finally, there is a lot of mathematical calculation behind complex decisions such as whether a business should raise money by issuing stock directly to the public as in the case of Google, or seek long-term loan financing? Both decisions involve quantification of risk and substantial probability analysis. A discount rate is used to determine the present value of the expected returns, and if a business anticipates being highly profitable in the short-term, it may be wiser to take out a bank loan, rather than dilute ownership via exanding the number of shares outstanding. Beyond major requirements within the mathematics department, you may consider Suffolk University aviation technology as an adjunct to your primary course of study.
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Name: Shubham Sharma
Society: Mirage- The Western Dance Crew of Nsit
Q.1. When and in which department were you recruited?
I was recruited in August 2015, in the performing team.
Q.2.What all targets are met by the society on a daily/monthly basis?
We try to complete as many routines as possible and they depend on when the next competition is going to be held.
Q.3.Does your society organize its own fest or participates in major inter/intra college events? Share your experiences.
We try to participate in as many inter college competitions as possible. The society organises Oorja, the western dance competition of NSIT during MOKSHA. My experience so far has been worth remembering. Mirage has improved me as a dancer, boosted my confidence, helped me in getting rid of stage fear and the list goes on. It is the only place in college where I love working hard.
Q.4.What overall improvements has the society brought out in your life?
The society has made me a better dancer, brought discipline in my life and improved my level of fitness. It has also boosted my confidence and helped me in expanding my social circle. It is my escape from the monotonous college life into a world of grace.
Q.5.Did you ever face problems in balancing society work, academics and personal life?
Not at all. Mirage has many members who are performing exceptionally well in academics. I myself have been scoring 75% on average. The seniors make sure that societies' work does not interfere with academics or personal life of any member.
Q.6.How frequent are the society meets and what all objectives are covered?
Our meetings are held every one week or two where we discuss our improvements and make plans for the further weeks to come.
Q.7.How is the interaction among society members?
The environment within mirage is very healthy. All the members gel up very well. Every member is always available for others, be it for mirage or any academic purpose.


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Fatals spur police advice
Two deaths in a week on South Canterbury roads have prompted police to remind drivers to look out for themselves and others, and to drive to the conditions.
The region's road toll for the first half of 2013 is three after a 64-year-old Ashburton man died at Otaio on Sunday afternoon.
Last week, a 5-week-old infant from Timaru died from injuries he suffered in a crash near Pareora.
The two accidents are under investigation, but police have seen other serious crashes recently that were related to winter driving conditions, according to Waimate Sergeant Mike van der Heyden.
On June 21, two Ikawai women were lucky to escape with their lives when their vehicle slid off a snowy bridge into Elephant Hill Stream. They were trapped up to their necks in the frigid water for about 45 minutes.
"We had another vehicle [on Monday] morning that slid off the icy gorge road and into Waimate Creek," Mr van der Heyden said. "People need to slow down and be sure to drive to the conditions because the roads are slippery."
But inattention and risk-taking were probably the most significant causes of crashes in general.
"Most are probably caused by poor observation or inattention."
Earlier this year, Fonterra worker Steve Kirkcaldie was killed when hit by a vehicle while cycling at the intersection of Milford-Clandeboye and Bain roads.
In 2012, South Canterbury's road toll was five.
"We should be looking at this and saying, as drivers, we have a responsibility to keep ourselves and our passengers safe," Senior Sergeant Randel Tikitiki said.
"The killers for New Zealand roads are fatigue, speed and not driving to the conditions. Particularly in Mid-South Canterbury, where we tend to travel long distances on relatively straight roads."
It also pays to practice defensive driving, he said. "The person in front or behind you might not be as good a driver as you are."
The Timaru Herald


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New flicks with celebs in interfaith relationships and from interfaith backgrounds, plus their baby news!
Jewish Camp is a valuable way for interfaith families to learn and share in the joy of Judaism in a comfortable, fun and meaningful environment. See which camps identify as welcoming to interfaith families.
The High Holy Days�or, High Holidays as they are also called�consist of two autumn holidays called Rosh Hashanah and Yom Kippur. Learn about the meaning and how to celebrate these holidays.
Connecting Interfaith Families to Jewish Life in Greater Cleveland by providing programs and opportunities for interfaith families to experience Judaism in a variety of venues, meet other interfaith families, and to connect to other Jewish organizations that may serve their needs.
This is an interactive, fun, and low-key workshop for couples who are dating, engaged or recently married. The sessions will give you a chance to ask questions about faith, to think about where you are as an adult with your own spirituality and to talk through what's important to you and your partner.
Supporting rabbis and cantors looking to engage interfaith couples and families in their communities and help them make a stronger connection with Judaism.
A great way for Jewish professionals and volunteers who work with and provide programming for people in interfaith relationships to locate resources and trainings to build more welcome into their Jewish communities; connect with and learn from each other; and publicize and enhance their programs and services.
This blog is written by IFF staff and ranges from reactions to news, personal opinions and resources or guides for couples, families or program providers.
See all interested members (1)Add to my events
A New Holiday Tradition Begins in Boston's Back Bay on December 18th with "A Light Through the Ages"
Boston Jewish Spirit will open its doors at its shared home at Emmanuel Church for "A Light Through the Ages", a holiday celebration of love, family, hope and peace. Presented by Boston Jewish Spirit and featuring the world renowned musicians of Emmanuel Music, this free holiday concert celebrates Chanukah's deep spiritual meaning through story and song and explores messages of major contemporary importance for people of all ages and backgrounds.
The original text of "A Light Through the Ages," written by Rabbi Howard A. Berman, was first performed in New York City 34 years ago, and provides a chronicle of the holiday from different times and places over the centuries. Choral selections of traditional and contemporary holiday music highlight the narrative, and the program concludes with a dramatic candlelight ceremony.
Copyright © 2015 InterfaithFamily.com, Inc. Privacy Policy


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Well I hope you all had a great Mother's Day! I know I did even though it was very busy! My family spoiled me and took me to my favorite restaurant for my favorite steak! MMMMM, was it ever good! Anyway, these two cards were for my two wonderful sisters who live so far away. I think they turned out so pretty yet so simple! I LOVE the Martha Stewart Hydrangea Punches. They are so pretty and versatile. You have many choices and things that you can do with them. Either way they both said that they really enjoyed getting them and thought that they were so beautiful.
I used:
Textured Pink and Blue Cardstock
White Velum Paper
White Pearl Cardstock for the frame and the BG behind the frame on the Pink card
DCWV Linen Closet Stack for the BG paper on the blue card
DCWV The French Country Stack for the Pink BG paper
Elegant Edges Cricut Cartridge for the frame cut
Potpourri Basket Cricut Cartridge for the Ivy
Cuttlebug Folder: Textile
Martha Stewart Pine Branch Punch
Martha Stewart Hydrangea Punches
Martha Stewart Scalloped Circle corner punch
Liquid Pearls
Well thanks for stopping in and checking out what I have been busy doing! I hope have a wonderful day!


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2 males 4 females. Akc papered . Mom and dad on site. Family raised with kids of all ages, cats, other dogs, indoor / outdoor activities. Taking 300…$1,000
I have three females, and three males. They are AKC German Shepherds with European bloodlines. I'm asking 1200 for limited register/pet. I'm asking 1500…$1,200
Have 5 males and 1 female Full Siberian Huskies have mom and dad on site will be derwormed and have 1st shots and are APR papered$750
Siberian husky puppies ready September 19, and September 25. Puppies are sold as a pet only on a spay/neuter contract. All puppies will have first set…$800
**AUTUMN IS A LOST GIRL FROM THE SOAP LAKE WA AREA, PLEASE HELP HER FIND HER WAY HOME**SHE IS NOT UP FOR ADOPTION UNTILL 10/9/17 THE QUINCY ANIMAL RESCUE…No Price Listed
If you are looking for a loving boy, Mac is your man! Provide the love and Mac will do the rest. He is a really adorable 10 mon, well mannered gentleman…No Price Listed
Chihuahua - Scooter - Small - Fullgrown - Male - Dog Scooter is an older Chihuahua who needs to find a home. He adores people, is friendly and affectionate…No Price Listed
This girl is in need of some TLC! She came to the shelter as a stray, very thin and hungry begging for some attention.She is a cute and gentle 1.5 yr old…No Price Listed


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|Publication number
|Publication type
|Application number
|Publication date
|Nov 1, 1988
|Filing date
|Apr 3, 1987
|Priority date
|Apr 11, 1986
|Fee status
|Also published as
|Publication number
|Finn Hannover
|Original Assignee
|Du Pont (U.K.) Limited
|Export Citation
|BiBTeX, EndNote, RefMan
|Patent Citations (13), Referenced by (7), Classifications (18), Legal Events (4)
|External Links: USPTO, USPTO Assignment, Espacenet
This invention relates to a method for lining tubular structures such as pipe, particularly, but not exclusively, long lengths of pipe in situ such as underground gas or water and sewer mains.
Metal pipes may be lined with thermoplastic polymers to convey corrosive material such as acids, or the lining may be used simply to rehabilitate or prolong the life of old, existing water or gas supply pipes or other pipes which may carry relatively non-corrosive fluids.
It has been proposed in U.S. Pat. No. 3,429,954 to line metal pipe by inserting into a pipe a longitudinally oriented heat shrinkable, irradiated thermoplastic polymer tubing, the tubing having in its unoriented state an outer diameter greater than the internal diameter of the metal pipe but slightly smaller than the internal diameter when oriented, and heating the tubing to a temperature above the crystalline melting point of the polymer to longitudinally shrink the polymer tubing and cause it to expand radially and fit tightly against the internal wall of the pipe.
The polymer tubings employed in U.S. Pat. No. 3,429,954 were irradiated to cross-link the polymer. This technique may be satisfactory for small diameter pipe, which is normally obtained and installed from a large coil. However, polymeric pipe having a diameter of greater than 3 or 4 inches is generally available only in straight lengths of several feet each, which must be joined by butt fusion or butt solvent welding techniques. Cross-linked polymers cannot with confidence be joined by fusion or solvent welding and are inferior in this respect to non-crosslinked thermoplastic polymers.
In the U.S. patent it is also suggested that the same polymer liners be expanded by heating using one of three methods.
(a) application of hot air internally
(b) passing the polymer lined pipe through a furnace so as to apply heat externally
(c) immersing the polymer lined pipe in a propylene glycol bath.
While methods (b) and (c) for obvious reasons are impractical for the relining of long, continuous lengths of underground pipe, method (a) is not effective either because in long pipe sections the air or any other gas or fluid will cool rapidly as it progresses along the pipe and there will be insufficient heat to raise the entire length of the polymer liners to the necessary temperatures.
A further problem in the lining of long lengths of metal pipe is that to achieve the proper expansion of the polymer liners inside the metal pipe, the liner must be completely free to shrink in the longitudinal direction. If the shrinkage is prevented or only slightly hindered in any way, it will result in no or only a reduced and insufficient expansion, as well as undesirable axial tensile stresses in the pipe that may be harmful to the fused or solvent welded joint.
In particular, where long, continuous lengths of pipe are to be lined, problems arise where the weight and associated friction drag of the long lengths of the lining itself, inside the metal pipe tends to prevent the required shrinkage. This situation may be further aggravated where the metal pipe is not completely straight and the liner becomes pinched or where the polymer liner during the expansion process itself expands unevenly or at a different rate either at various points along the length of the liner where it may tend to hang up, or around the periphery of the liner where this may cause the liner to curve in the length direction inside the metal pipe and thereby become pinched.
It is the object of this invention to provide a method particularly for lining long lengths of underground pipe that will overcome all of the above mentioned difficulties and problems.
The present invention provides a process for lining a pipe with a thermoplastic polymer which comprises:
(a) selecting a substantially non-crosslinked, expandable, thermoplastic tubular polymer liner having an outside diameter less than the internal diameter of the pipe and which, when fully expanded, would have an outside diameter greater than the internal diameter of the pipe;
(b) inserting the tubular polymer liner into the pipe; and
(c) heating the polymer liner sequentially from one point toward at least one free end of the pipe and uniformly about its circumference to a temperature sufficient to cause the liner to expand while applying positive axial pressure on the end of the liner toward which the liner is being heated.
FIG. 1 illustrates in diagrammatic sectional from practice of the method of this invention in lining an underground pipe;
FIG. 2 is a sectional view of FIG. 1 taken on line 2--2;
FIG. 3 is an illustration of a portion of FIG. 1 modified to show a different method of applying axial pressure to the thermoplastic liner;
FIG. 4 is a section through a pipe and liner showing a modified radiant heater; and
FIG. 5 is a partly cut away side view of a preferred heater which can be used in the instant invention.
Thermoplastic polymers which can be used in the practice of this invention include any non-crosslinked, thermoplastic homopolymers and copolymers which are capable of maintaining a deformation brought about from being heated, stretched and cooled, and which return to their approximate original dimension up reheating.
Specific examples include homopolymers such as polyethylene, polypropylene, polybutene; copolymers of ethylene and vinyl esters of aliphatic carboxylic acids such as vinyl acetate and vinyl propionate; copolymers of ethylene and alkyl acrylate and methyl methacrylate; copolymers of ethylene and other alpha-olefins such as propylene, butene, hexene and octene; copolymers of ethylene and ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid and the like. Still other classes of thermoplastic materials which can be used include polyacetals, polyvinyl chloride and chlorinated polyvinyl chloride, polyamides and acrylics such as polymethyl methacrylate.
Preferred thermoplastic materials which can be used in the invention include polyethylene such as that manufactured by Du Pont under the Trade Mark ALATHON, ethylene-octene and ethylene-hexene copolymers.
In a preferred method of preparing the liners used in the present invention, the polymer liner is first heated to a temperature within the normal annealing temperature range of the polymer, and preferably to a temperature which is about from 10 to 30 Centigrade degrees below the melting point of the polymer. The liner is then stretched to reduce the outer diameter sufficiently so that upon cooling to room temperature and removal of the tension, the dimensionally stable outside diameter is less than the internal diameter of the pipe to be lined.
A polyethylene liner capable of expanding about from 8 to 15% of its diameter, for example, can be made from a tubular polyethylene billet with an outside diameter slightly larger than that of the internal diameter of the pipe by:
(a) heating the billet to a temperature in the range 105� to 120� C. or about 10� to 20� C. below its crystalline melting point
(b) stretching the tubular billet at this temperature in the range 1.3� to 1.7� its original length
(c) cooling the stretched tube under tension to room temperature
(d) relieving the tension and permitting the tube to relax for a period of time (usually 2 to 3 days) until the dimension remains stable.
Preferably the outside diameter of the unexpanded liner is 5 to 12% smaller than the nominal inside diameter of the tubular structure so that one liner size may accommodate a narrow range of different pipe inside diameters.
It is normally necessary to join a series of pieces of liner together to produce a sufficient continuous length.
In the process of butt welding it is normal to clamp two pieces of pipe adjacent to each other, face off their adjacent end surfaces, apply heat to these end surfaces to affect some melting and then bring the two face surfaces or ends of the pipes together so as to butt weld the two portions together. If this is done with pipe which has been stretched such as the liners used in the present invention, the heat will cause circumferential expansion of the pipe or liner at the joint which will create an undesirable bulge at the joint. To avoid this, during the butt welding the two ends of liner or pipe must be clamped as near as possible to the junction and the diameters at this point must be slightly compressed or reduced to counteract the tendency of the pipe to expand as it is heated. By maintaining the clamp compression close to and on each side of the joint during the welding and until the joint has cooled to room temperature, it is possible to make a butt fusion without any diameter distortions or bulges.
A preferred method of joining successive sections of the heat expandable liner by butt heat fusion involves
(a) circumferentially compressing the end of each stretched liner section to be joined about from 1 to 5% by clamping each such end with a circumferential clamp;
(b) positioning the clamps or stops on the equipment to permit the faced off ends of each liner section to protrude from the edge of each clamp about from 0.5 to 1.5 times the thickness of the liner;
(c) heating the ends of the liner sections to be joined to the fusion temperature of the thermoplastic from which the liner is made; and
(d) bringing the ends of the heated liner section into contact under pressure and maintaining the contact until the temperature of the ends falls to substantially ambient temperature.
Typically the interfacial pressure applied during the fusion of the ends of the liner sections is about from 40 to 60 psi.
After joining successive sections, the beads on the inside and outside of the pipe are typically cleaned by conventional means. Internal cleaning is described, for example, in Brandt, U.S. Pat. No. 3,805,311, hereby incorporated by reference.
Thus by successively joining sections it is possible to insert into the metal pipe a total length of heat expandable liner which should typically be about from 10 to 35% longer than the metal pipe to allow for longitudinal shrinkage which will vary depending on the required expansion.
To expand the liner it is preferably heated from the inside of the liner with a radiant infra-red heater. The polymer liner should be heated uniformly about its circumference and sequentially from one point toward at least one free end of the pipe. Accordingly, the radiant heater may be inserted into the liner, either to an intermediate point or at the end of the pipe, and moved through the pipe towards an open end from said intermediate point or from said one end at a rate such as to relieve the internal strain applied by the stretching and to allow for full expansion of the polymer liner into contact with the internal surface of the pipe. The method of moving the heating zone from an intermediate point or from one end is to ensure that the longitudinal shrinkage which is associated with radial expansion can take place unhindered.
To obtain the best expansion and fit with the internal diameter of the pipe to be lined and to protect the fused or welded joints, an axial compressive force is preferably applied at the free end of the polymer pipe toward which the heater is moving so as to overcome frictional drag forces from the weight of the not yet expanded section of the liner, to overcome the resistance forces from pinch points along the pipe and in this way assist in the movement of the unexpanded liner section to accomplish the required axial shrinkage. Preferably this axial force should produce some axial compression in the zone of the expansion during the entire operation. Preferably, the axial pressure applied is equal to about from 100 to 400 psi of the cross-sectional area of the pipe wall.
The radiant heater may, for example, be in the form of a rod or bar supported at one end on a carriage which is shaped to conform to the shape of the liner and is slid along the liner. A preferred heater which can be used in the present invention, having anterior and posterior ends, comprises:
(a) a platform;
(b) at least one radiant heating element mounted on the platform;
(c) a spiral air tube mounted on the platform to encircle the heating element at least once in a direction axial to the liner, the air tube having a plurality of apertures formed therein positioned to create a circumferential air flow within the pipe;
(d) electrical and pressurized air sources functionally connected to the radiant heating element and air tube, respectively;
(e) means for moving the platform through the pipe; and
(f) a diametric gasket positioned anterior to the heating element to separate the apparatus from the portion of the pipe anterior to the heating element.
In the installation of pipe liner according to the present invention, the liner may not conform in minute detail to the inside of the pipe which may be rough, uneven or pitted. Further, if good conformation of the pipe liner and the pipe wall is initially obtained, temperature variations in the pipeline can cause a gap between the liner and the pipe wall. In the event that a leak in the system should develop, detection and repair of the leak would be difficult.
Accordingly, in another preferred embodiment of the invention, the pipe liner has a coating of about from 10 to 100 mils on the outer surface thereof of a thermoplastic elastomer hot melt adhesive, the thermoplastic elastomer having a flexural modulus of about from 500 to 10,000 psi and a melting point of about from 40� to 120� C. Preferably, the polymer has a melting point of about from 50� to 100� C., and melting points of about from 65� to 85� C. are especially preferred.
As the heater is moved through the liner, the outside surface of the liner reaches temperatures that will melt or soften the thermoplastic elastomeric melt adhesive. As the liner simultaneously expands and presses against the internal surface of the pipe, a good bond between the pipe and the liner is assured.
Thermoplastic elastomers which can be used in a coating for the pipe liner include, for example, ethylene vinyl esters, ethylene acrylate copolymers, ethylene olefinic copolymers such as ethylene propylene rubbers, styrene isoprene, styrene butadiene or styrene ethylene propylene block copolymers. These materials can be functionalized with a comonomer which gives good adhesion to metals, such as maleic anhydride, the half-ester of maleic anhydride, acids such as methacrylic acid, acrylic acid or itaconic acid or epoxy functionalized or saturated monomers such as glycidyl methacrylate or acrylate. By controlling the comonomer content and selecting the proper comonomer, these materials can adhere well to the polymer of the pipe liner by direct copolymerization or by a grafting reaction.
The coating of thermoplastic elastomers can be applied to the surface of the pipe line either continuously or intermittently. The coating can be applied by conventional coating means or in the form of a tape that is wrapped around the pipe and subsequently heat fused to provide an integral coating.
The invention may be more fully understood by reference to the Figures.
In FIG. 1 is shown an iron gas main 10 which is located underground and may be several feet below ground level 11.
The gas main is to be lined with a polyethylene pipe liner 12.
The length of prestressed polymeric pipe liner 12 is chosen to be of larger length than the pipe 10. The outer diameter of the polymeric liner is not more than 10% less than the internal diameter of the pipe 10.
One end 13 of the iron pipe is exposed by excavating a cavity in the ground, the cavity being sufficiently large to feed through a long length of polyethylene pipe liner which may, for example, be about 10 to 12 meters in length.
The polymeric pipe liner is then inserted into the pipe 10 leaving a portion of the length of the polymeric pipe liner exposed so as to allow for axial shrinkage of the liner during the subsequent radial expansion within the pipe.
A radiant heater 14 which is preferably in the form of an elongated tube is then inserted into the liner on a carriage 15. The carriage 15 is shaped to conform to the shape of the liner so that it will slide freely along the liner and has a post 16 at one end of which the heater 14 is cantilevered.
At the other end is a second post 17 to which is attached a rope or cable 18 which may incorporate the wires carrying the power supply to the heater 14. Alternatively separate wires may be provided to the heater 14.
The rope or cable 18 passes around the pulley 19 and to a motor 20 which can provide a steady gentle pull on the rope 18 so as to pull the carriage or sledge 15 at a predetermined steady rate through the pipe. The motor 20 is preferably variable in speed so as to adjust the speed at which the carriage 15 moves through the pipe.
It has been found in practice that it is desirable to position the radiant heater 14 so that it is below the mid-level of the liner to ensure that the portion of the liner at the lowermost part of the pipe receives sufficient heat.
Since the liner is most likely resting on the bottom of the metal pipe this is where the more important heat sink is. For this reason this area should receive the highest heat intensity from the infrared heater. Since the top of the liner is not initially in contact with the steel pipe--and therefore, has no heat sink--and at the same time is favored as far as convective heat transfer is concerned, this area should receive the lowest heat intensity from the radiant heater. This is achievable with the type of improved heating arrangement shown in FIG. 4.
A central support tube 25 carries the electric wiring supplying four radiant rod heaters 27, 29, 31, 33 of the infrared type, each being provided with a reflector 26, 28, 30, 32 respectively. The reflector 32 and heater rod 33 are located much further from the center line of the pipe than the other heaters are.
The infra-red heaters preferably operate in the range 2 to 3 u., i.e., in the medium range of infrared spectrum. Preferably, the stretched liner is heated in the presence of an inert gas.
An incentive for using infrared heating is that polyethylene over a large range of wave lengths is somewhat transparent to infra-red radiation. This means that a significant proportion of the infra-red energy penetrates into the polyethylene liner wall directly causing it to heat up faster than if it was heated up by other means which depend solely on conduction through the pipe wall.
The heater 14 is then pulled gently through the pipe and liner so as to cause the liner to expand and attempt to return to its original diameter thus making an effective tight seal against the inner circumference of the pipe 10.
Because of drag and weight of the liner when such long lengths of liner are employed, the expansion may not occur uniformly and fully. To overcome this problem an axial thrust or force is preferably applied to the liner 12, for example, by means of a block or bar 21 connected by rods 22 to jack devices 23 which may be set to provide a steady pull on the block 21 so as to overcome any drag or inertia of the liner as it proceeds into the pipe.
The jacks may be automatic devices which provide a constant pull or they may be operated manually and the force applied may be adjusted to suit particular lengths of liner and weights of liner and drag situation.
In FIG. 3 an alternative method is shown of applying the axial force to the liner. A clamp 24 is used which again may be attached via rods 22a to suitable jacks similar to 23. By attaching the clamp 24 at a point fairly close to the entrance 13 of the pipe 10 a better control can be achieved on the axial force applied without distorting the liner.
A preferred heater for use in the present invention is shown in FIG. 5. In that Figure, platform 50 has two radiant heating elements 51 mounted ontthe platform through support means 52. Spiral air tube 53 is similarly mounted on the platform to encircle the heating element. Apertures 54 are formed in the air tubes in such positions as to create a circumferential air flow within the pipe liner. Blower 55 provides a pressurized air source connected to the air tube. The blower is powered by a motor 56. The motor and radiant heating elements are respectively connected to electrical sources 57 and 58. Diametric gasket 59 is positioned anterior to the heating element to separate the apparatus from the portion of the pipe preceding the heater. Optional posterior diametric gasket 60 similarly isolates the portion of the pipe behind the heating apparatus. The heating apparatus can be either drawn or pushed through the pipe liner by attaching means 61.
It has been found to be particularly convenient to mount the air tube and the heating element on a common suspension, as shown in the Figure. While a single radiant heater can be used, particularly with smaller sized pipe, it is preferred to position two or more heaters, as shown, substantially equidistant from the center of the pipe.
The present invention provides a method for lining pipe that not only effectively seals decayed pipe, but can be efficiently operated by a relatively small work force. Example
An iron gas pipe 10 which had lain in the ground for 50 years was to be lined with a polythene liner so as to extend the life of the original pipe. It was important to retain the volume flow through the pipe and so the liner was selected to cause the minimum reduction cross-sectional area of the original pipe and had to be brought into firm contact with internal surface of the pipe 10.
The pipe 10 was a 20 ft (6 m) 8 inch nominal diameter cast iron main with an average inside diameter of 8.4 inches (21.4 cm).
A polyethylene liner was selected with an outside diameter of 8.95 inches (22.7 cm) and a wall thickness of 0.29 inches (0.75 cm) produced from an ethylene octene-1 copolymer having a melt index of 1 and a density of 0.937 g/cc containing antioxidants and pigment.
The polyethylene liner was heated to a temperature of 113� C. over a period of 1 hour and subsequently stretched 1.5�. After the liner had cooled to room temperature in this state the tension was released and the liner was permitted to relax. After three days, no further dimensional changes were noticable and the outside diameter of the liner remained 7.65 inches (19.4 cm).
A 25 ft (7.72 cm) long section of this liner was inserted into the 20 ft (6 m) long cast iron pipe in such a way that the liner and pipe were flush at one end with the longer length liner extending 5 ft out of the other pipe end 13.
A heater, of the design shown in FIG. 5, using four 1 ft long, 3/8 inch diameter 1 kw cartridge heaters was slid into the liner so that the heater elements extended just outside the far end, with the carriage section supported inside the liner.
After the current was turned on and the heater cartridges had reached their maximum temperature, the motor was started and the heater carriage progressivly moved along the pipe from right to left as shown in FIG. 1. As soon as the end of the heater was about 6 inches inside the liner, the end of the liner was plugged and the air source was turned on. At the same time, axial pressure of 100 pounds per square inch of liner wall thickness was applied by means of the mechanism shown in FIG. 1. By moving the heater carriage at a rate of 4 to 5 inches/minute along the liner, the liner expanded to provide a good fit with the internal diameter of the cast iron pipe. The axial pressure ensured that full radial expansion took place. In the course of the radial expansion and axial contraction the portion of the liner extending outside of the pipe contracted into the pipe.
|Cited Patent
|Filing date
|Publication date
|Jan 18, 1940
|Feb 29, 1944
|Youngstown Sheet And Tube Co
|Method of applying protective coatings for metal
|Dec 11, 1944
|Jul 25, 1950
|Amercoat Corp
|Method of lining pipes and other structures with plastic sheets
|Jun 19, 1952
|May 15, 1956
|Garten Wilhelm
|Method of lining a metal pipe
|Mar 20, 1961
|Jun 5, 1962
|Crutcher Rolfs Cummings Inc
|Internal treatment of pipes
|Feb 11, 1960
|Oct 15, 1963
|Shirlow Corp
|Apparatus for performing work on the internal wall of piping
|Oct 31, 1977
|Jan 2, 1979
|Tektronix, Inc.
|Feedbeside correction circuit for an amplifier
|Sep 8, 1980
|Oct 5, 1982
|Mcelroy Arthur H
|Defined force fusion machine for joining plastic pipe
|Dec 13, 1982
|Oct 18, 1983
|Umac, Inc.
|Apparatus for relining an underground gas line or the like without excavation
|Feb 12, 1982
|Jul 15, 1986
|Asahi Kasej Kogyo Kabushiki Kaisha
|Thermoplastic elastomers
|Aug 21, 1979
|Aug 26, 1980
|Perry N. Brittain
|Process for lining high pressure pipeline
|Title not available
|Title not available
|Title not available
|Citing Patent
|Filing date
|Publication date
|Nov 22, 1988
|Mar 19, 1991
|Allied Tube & Conduit Corporation
|Method and apparatus for manufacturing plastic-lined pipe
|Jul 26, 1990
|Oct 8, 1991
|Allied Tube & Conduit Corporation
|Apparatus for manufacturing plastic-lined pipe
|Jan 7, 1992
|Jun 29, 1993
|Gundle Lining Systems, Inc.
|Method of sealing lateral connections for pipe liners
|Oct 21, 1999
|Oct 9, 2001
|Ledoux Patrick
|Method for forming and sealing pipe liners
|Jan 13, 1997
|Oct 16, 2001
|Uponor Innovation Ab
|Method for lining underground pipelines
|Sep 16, 2002
|Mar 20, 2003
|Method of installing a tubular element
|Oct 27, 2008
|Apr 29, 2010
|Ipex Inc.
|Pipe stop system and method to prevent over insertion
|U.S. Classification
|156/287, 156/304.2, 264/230, 156/294
|International Classification
|Cooperative Classification
|European Classification
|Jun 5, 1987
Owner name: DU PONT (U.K.) LIMITED, WEDGWOOD WAY, GB-STEVENAGE
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:HANNOVER, FINN;REEL/FRAME:004720/0086
Effective date: 19870406
|Apr 24, 1992
|Fee payment
Year of fee payment: 4
|Apr 24, 1996
|Fee payment
Year of fee payment: 8
|Apr 17, 2000
|Fee payment
Year of fee payment: 12


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Download Cape Town Accommodation apk 184.108.40.2066 free for Android smartphone
Posted by Modern Web Presence in Travel & Local | Aug. 20, 2015 | 0 Comments
Apk file size: 19.0 MB
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At the recent UK Drives and Controls exhibition, Inverteks UK distributor Moeller Electric - demonstrated how Optidrive can be used to save energy and money.
An innovative display on the stand utilised a 2,700litre fridge with a 3kW cooling capacity. This was powered by a 1kW compressor and two condenser fans rated at 125W and controlled by an Optidrive. Connecting Optidrive to a temperature sensor, via a PI controller, allows the motor running speeds to be optimised to save energy and maintain highly consistent temperatures.
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For some it's more appreciation. For some it's newly surfaced regrets.
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