Ion Transport

This article describes a working hypothesis of the nature of the 'suicide condition' (SC). The authors contend that the SC emerges as a specialized result of two-phase impairment in the neuroimmunological 'inherited schematic representation' (ISR) involving: (a) the formation of a 'microcellular suicide' phenomenon; and (b) the establishment of a 'macro-organismic suicide' program. Our hypothesis, unlike earlier ones, is based on scientific evidence spanning diverse clinical diagnostic areas indicating that the SC is induced by a local histoincompatibility across distinct tissue structures and/or a remodeling of one or more neurimmunological ISR designs due to biophysical ion shunt bypass and neglect, whereas a normal neuroimmunological ISR complex produces an allembracing organismic histocompatible tissue-syntonic-to-ego-syntonic expression. The presence of abnormal 'microcellular suicide' assemblies leads to cell syntonic-to-cell dystonic transformation and initiates the first modification phase by contaminating certain neurimmunological ISR programs which in turn trigger the onset of partial ego syntonic-to-ego-dystonic conversion. This is translated by the self-conscious experience as partial self-to-alien tissue translocation. These formations accumulate at a rate, arriving at the second phase in SC establishment when they reach a magnitude resolution that surpasses the organismic suicide threshold level and increase the amount of ego-syntonic-to-ego-dystonic inclusion. This is then translated by the self-conscious experience as a 'foreseeable and inescapable death' that is based on severe self-to-alien multiorgan substitution. The latter overcomes the rules and regulations prescribed by impulse-induced inner events, regardless of outer psychosocial events, and leads to an irrevocable drive to suicide.

Our study aimed at investigating the influence of elevated atmospheric CO 2 concentration on the salinity tolerance of the cash crop halophyte Aster tripolium L., thereby focussing on protein expression and enzyme activities. The plants were grown in hydroponics using a nutrient solution with or without addition of NaCl (75% seawater salinity), under ambient (380 ppm) and elevated (520 ppm) CO 2 . Under ambient CO 2 concentration enhanced expressions and activities of the antioxidant enzymes superoxide dismutase, ascorbate peroxidase, and glutathione-S-transferase in the salt-treatments were recorded as a reaction to oxidative stress. Elevated CO 2 led to significantly higher enzyme expressions and activities in the salt-treatments, so that reactive oxygen species could be detoxified more effectively. Furthermore, the expression of a protective heat shock protein (class 20) increased under salinity and was even further enhanced under elevated CO 2 concentration. Additional energy had to be provided for the mechanisms mentioned above, which was indicated by the increased expression of a b ATPase subunit and higher v-, p-and f-ATPase activities under salinity. The higher ATPase expression and activities also enable a more efficient ion transport and compartmentation for the maintenance of ion homeostasis. We conclude that elevated CO 2 concentration is able to improve the survival of A. tripolium under salinity because more energy is provided for the synthesis and enhanced activity of enzymes and proteins which enable a more efficient ROS detoxification and ion compartmentation/transport.

Mitochondria promptly respond to Ca 2+ -mediated cell stimulations with a rapid accumulation of the cation into the matrix. In this article, we review (i) the basic principles of mitochondrial Ca 2+ transport, (ii) the physiological/pathological role of mitochondrial Ca 2+ uptake, (iii) the regulatory mechanisms that may operate in vivo, and (iv) the new targeted Ca 2+ probes that allowed the brediscoveryQ of these organelles in calcium signalling. D

# Springer-Verlag 2005 of cystic fibrosis transmembrane regulator, KCNQ1, and CLCA1 mRNAs were not found to be different between the two segments. Conclusion: There was a clear segmental heterogeneity with regard to electrogenic secretion in the human colon, and this difference can be explained by differences in the ascending colon and rectum.

It is generally assumed that bumetanide possesses some selectivity for the renal Na-K-Cl cotransporter NKCC2, although the results are scarce in the literature and comparisons were done with extra-renal NKCC1 at its basal, almost silent state. Here we investigated NKCC2/NKCC1 selectivity of loop diuretic drugs (bumetanide, piretanide and furosemide) as a function of the NKCC1 activated state (NKCC1 was activated by hypertonic media). NKCC2 activity was measured in isolated rat medullary thick ascending limb (mTAL) and NKCC1 in rat thymocytes and erythrocytes. When NKCC2 was compared with NKCC1at its activated state, all three diuretic drugs inhibited NKCC2 and NKCC1 with the same potency (bumetanide pIC 50 =6.48, 6.48 and 6.47; piretanide pIC 50 =5.97, 5.99 and 6.29; and furosemide pIC 50 =5.15, 5.04 and 5.21 for mTAL NKCC2, erythrocyte NKCC1 and thymocyte NKCC1, respectively). Basal NKCC1 exhibited a lower diuretic sensitivity, although with marked differences depending on the diuretic drug and the cell type in consideration and with the notable exception of furosemide in erythrocytes. Molecular modelling showed that bumetanide and piretanide possess four potentially active groups, of which three are shared with furosemide at similar intergroup distances. Of these three common groups, one should not bind to basal NKCC1 in thymocytes. The fourth (phenoxy) group (absent in furosemide) confers higher lipophilicity and should not bind to basal NKCC1 in erythrocytes. In conclusion, loop diuretics had no NKCC2/NKCC1 selectivity, when NKCC1 is measured at its activated state. Basal NKCC1 has a reduced diuretic sensitivity, of very different magnitude depending on the diuretic drug and cell type in consideration.

When grown on rigid substrates in confluent monolayers, MDCK and other epithelial cell lines form "dome" structures. These domes are formed by cells that lifte up from the solid support but are continuous with the monolayer (as represented in the schematic below). There is sporadic data in the literature about signalling pathways that control this behaviour and I list a

Transport is the outstanding physics issue in the quest for fusion by magnetic confinement. In spite of the intrinsic difficulty, a great deal of progress has been made in the past 25 years. Experiments have gone from being dominated by high anomalous losses, of the order of Bohm diffusion losses, to operation with no anomalous transport. This success is due to a combination of improved experimental infrastructure and the high degree of knowledge on how to control plasma discharges. Both have made it possible to access enhanced confinement regimes and to unravel new effects in confinement physics. Although there is not yet a complete understanding of the dynamical mechanisms underlying the anomalous transport process, there is some understanding of important components such as the ion transport loss mechanism at the plasma core and of the main mechanism for turbulence suppression in the enhanced confinement regimes.

The mechanism by which nonsteroidal antlinflammatory drugs interfere with the action of loop diuretics is not clear. We studied the renal response to an acute challenge of piretanide superimposed on pretreatment with either placebo, probenecid, indomethacin, or piroxicam in seven maximally hydrated subjects. No change was seen in glomerular filtration rate, as measured by creatinine clearance, throughout the experiments. When compared with responses to piretanide challenge after placebo pretreatment, probenecid reduced by 65% the peak fractional excretion of sodium (FENa), with a corresponding reduction in diuretic excretion. Pretreatment with indomethacin reduced peak FENa by 35%, but urinary delivery of piretanide was not altered. In contrast, piroxicam did not influence FENa but significantly reduced the delivery of both sodium and piretanide into urine. We conclude that the activity of nonsteroidal antiinflammatory drugs within the renal tubule varies among individual drugs and cannot be explained solely by their common mechanism of antiinflammatory action.

The regulation of membrane-transport activity is crucial for intracellular pH homeostasis, maintenance of cell osmotic potential, nutrient acquisition, signalling, and adaptation of bacterial cells. The non-invasive microelectrode ion flux estimation (MIFE) technique is a powerful tool for kinetic studies of membranetransport processes across cellular membranes. Since 2001, when this technique was first applied to the study of membrane-transport processes in bacterial cells (J Microbiol Methods 46, 119-129), a large amount of information has been accumulated. This review summarizes some of these findings and discusses the advantages and applicability of this technique in studying bacterial adaptive responses to adverse environmental conditions. First, various methodological aspects of the application of this novel technique in microbiology are discussed. Then, several practical examples ('case studies') are described. The latter include changes in membrane-transport activity in response to various stresses (acidic, osmotic, and temperature stresses) as well as flux changes as a function of bacterial growth stage and nutrient availability. It is shown that non-invasive ion flux measurements may provide a significant conceptual advance in our understanding of adaptive responses in bacteria, fungi and biofilms to a variety of environmental conditions. The technique can also be used for the rapid assessment of foodprocessing treatments aimed at reducing bacterial contamination of food and for the development of strategies to assess the resistance of organisms to antimicrobial agents. FEMS Microbiol Rev 30 (2006) 472-486 c

Little is known about the molecular and regulatory mechanisms of long-distance nitrate transport in higher plants. NRT1.5 is one of the 53 Arabidopsis thaliana nitrate transporter NRT1 (Peptide Transporter PTR) genes, of which two members, NRT1.1 (CHL1 for Chlorate resistant 1) and NRT1.2, have been shown to be involved in nitrate uptake. Functional analysis of cRNA-injected Xenopus laevis oocytes showed that NRT1.5 is a low-affinity, pH-dependent bidirectional nitrate transporter. Subcellular localization in plant protoplasts and in planta promoter-b-glucuronidase analysis, as well as in situ hybridization, showed that NRT1.5 is located in the plasma membrane and is expressed in root pericycle cells close to the xylem. Knockdown or knockout mutations of NRT1.5 reduced the amount of nitrate transported from the root to the shoot, suggesting that NRT1.5 participates in root xylem loading of nitrate. However, root-to-shoot nitrate transport was not completely eliminated in the NRT1.5 knockout mutant, and reduction of NRT1.5 in the nrt1.1 background did not affect rootto-shoot nitrate transport. These data suggest that, in addition to that involving NRT1.5, another mechanism is responsible for xylem loading of nitrate. Further analyses of the nrt1.5 mutants revealed a regulatory loop between nitrate and potassium at the xylem transport step.

It is shown that only 10% of the 99wt% water present in bacterial cellulose (BC) gels, produced by Acetobacter xylinum, behave like free bulk water; the majority of the water molecules in the gels is more or less tightly bound to the cellulose. The magnitude of the diffusion coefficients of ions transported in the water phase of the BC gels

The formation of dentin, dentinogenesis, comprises a sophisticated interplay between several factors in the tissue, cellular as well as extracellular. Dentin may be regarded as a calcified connective tissue. In this respect, as well as in its mode of formation, it is closely related to bone. Using dentinogenesis as an experimental model to study biomineralization provides several practical advantages, and the results may be extrapolated to understand similar processes in other tissues, primarily bone. After describing dentin structure and composition, this review discusses items such as the morphology of dentinogenesis; the dentinogenically active odontoblast, transport, and concentrations of mineral ions; the constituents of the dentin organic matrix; and the presumed mechanisms involved in mineral formation.

This work gives estimated values of the velocity correlation coefficients VCCs for ternary electrolyte solutions (the system may have a tracer ion as one of the components), utilizing available measured transport coefficients. The VCCs originate from linear response theory and give a deeper insight into the microdynamic structure of complex ionic solutions. By assuming Onsager's relation to be valid, ten sets of velocity correlation coefficients were calculated for a ternary system and were used to calculate the VCCs for 134 Cs + ion (present in trace amount) transport in aqueous solutions of CsCl and KCl at 25 • C. Keywords Velocity correlation coefficients • Cs + ion transport • Diffusion coefficients • Sliding cell method • Radioactive tracer technique • Aqueous CsCl solution • Aqueous KCl solution

The electrochemical, rheological, calorimetric, spectroscopic and morphological investigations have been used to examine poly(methyl methacrylate), PMMA based electrolytes dispersed with nano-sized fumed silica (SiO 2 ). The observed ionic conductivity was one of the highest and is of the order wmS/cm at ambient temperature which was studied as a function of concentration of fumed silica nano-particles. It was further found that the fumed silica acted as a passive filler and played a predominant role in controlling the rheological properties while ion transport properties were least effected. The differential calorimetry studies revealed single glass transition temperature pointing towards homogeneous nature of the composite polymeric electrolytes (CPEs). At an optimum concentration of fumed silica (2 wt%) the observed maximum conductivity and morphology was attributed to the presence of a strong network structure, while at a higher concentration the elastic behavior was more pronounced which impeded ion transport. This contention was supported by spectroscopic data. q .in (S.A. Agnihotry).

Connective tissue growth factor (CTGF) is a member of the CCN family of secreted, matrix-associated proteins encoded by immediate early genes that play various roles in angiogenesis and tumor growth. CCN family proteins share uniform modular structure which mediates various cellular functions such as regulation of cell division, chemotaxis, apoptosis, adhesion, motility, angiogenesis, neoplastic transformation, and ion transport. Recently, CTGF expression has been shown to be associated with tumor development and progression. There is growing body of evidence that CTGF may regulate cancer cell migration, invasion, angiogenesis, and anoikis. In this review, we will highlight the influence of CTGF expression on the biological behavior and progression of various cancer cells, as well as its regulation on various types of protein signals and their mechanisms.

Phaeocystis globosa, a leading agent in marine carbon cycling, releases its photosynthesized biopolymers via regulated exocytosis. Release is elicited by blue light and relayed by a characteristic cytosolic Ca 2+ signal. However, the source of Ca 2+ in these cells has not been established. The present studies indicate that Phaeocystis' secretory granules work as an intracellular Ca 2+ oscillator. Optical tomography reveals that photo-stimulation induces InsP 3 -triggered periodic lumenal [Ca 2+ ] oscillations in the granule and corresponding out-of-phase cytosolic oscillations of [Ca 2+ ] that trigger exocytosis. This Ca 2+ dynamics results from an interplay between the intragranular polyanionic matrix, and two Ca 2+ -sensitive ion channels located on the granule membrane: an InsP 3 -receptor-Ca 2+ channel, and an apaminsensitive K + channel.

A simple HPLC method with fluorescence detection of ciprofloxacin in human plasma was developed and validated. After protein precipitation, chromatographic separation of ciprofloxacin in plasma was achieved at 35 8C with a C18 column and acetonitrile Á/phosphate mixture, pH 3, as mobile phase. Quantitative determination was performed by fluorimetry after excitation at 278 nm. The method was specific and validated with a limit of quantification of 41 ng/ml. The intra-and inter-day coefficients of variation were between 0.5 and 6.6% and accuracy between (/2.02 and 7.04%. Ciprofloxacin was stable in plasma for 40 days at (/20 8C and after three freezing-thawing cycles. The method has been applied in a bioequivalence study of two formulation of 500 mg ciprofloxacin. #

Recombinant interleukin-I (rIL-I) is known to inhibit glucose-induced insulin secretion by islets of Langerhans, a novel target tissue of cytokine. We have investigated whether rIL-I pretreatment affects biochemical mechanisms known to be involved in the regulation of Ca 2' homeostasis during glucose-induced insulin secretion. Glucose-induced Ca2+ uptake by intact islets through the plasma membrane was dramatically inhibited (96%) by rIL-I (2 nM). rIL-1, however, did not affect Ca2+ uptake by, or Ins I ,4,5-P,-induced Ca *+ efflux from, the endoplasmic reticulum in digitonin-permeabilized islets, although glucose-induced accumulation of inositol trisphosphates was inhibited (38%). These results suggest that perturbation of intracellular Ca 2+ homeostasis in islets is involved in inhibition of insulin secretion by rIL-I.

Astrocytes are involved in multiple brain functions in physiological conditions, participating in neuronal development, synaptic activity and homeostatic control of the extracellular environment. They also actively participate in the processes triggered by brain injuries, aimed at limiting and repairing brain damages. Purines may play a significant role in the pathophysiology of numerous acute and chronic disorders of the central nervous system (CNS). Astrocytes are the main source of cerebral purines. They release either adenine-based purines, e.g. adenosine and adenosine triphosphate, or guanine-based purines, e.g. guanosine and guanosine triphosphate, in physiological conditions and release even more of these purines in pathological conditions. Astrocytes express several receptor subtypes of P1 and P2 types for adenine-based purines. Receptors for guanine-based purines are being characterised. Specific ecto-enzymes such as nucleotidases, adenosine deaminase and, likely, purine nu...

The salinity tolerance and ion transport of 2-month-old seedlings of stone pine (Pinus pinea L.) grown in hydroponic solution containing various concentrations of NaCl (0-100 mM) were studied. The presence of salt of up to 100 mM did not significantly reduce growth. Seedling hydration was insensitive to salinity. High salt concentrations reduced K ? and Ca 2? uptake, root accumulation, and export to shoots. Na ? and Clions, representing the major part of the ionic uptake, were effectively compartmentalized in vacuoles. We concluded that seedlings of stone pine cultivated hydroponically were highly tolerant to salt concentrations of up to 100 mM for a culture period of 38 days. This tolerance was associated with the accumulation of Na ? and Clions in the shoots.

In Formica Malpighian tubules KC1 secretion is driven by a V-type H + ATPase in the luminal membrane in parallel with a H+/K + antiporter. The effect of the protonophore dinitrophenol (DNP) was investigated on the isolated, symmetrically perfused tubule. DNP was applied in two different concentrations : 0.2 mmol/1 and 1 mmol/1. The effects were fast and rapidly reversible. The equivalent short-circuit current (/so) was reduced significantly to respectively 25---3% Cn = 4) and -3 -7% (n = 11) of the control value when 0.2 mmol/ 1 or 1 mmol/1 was added to the bath. When 1 mmol/1 DNP was applied the transepithelial resistance (Rt~) decreased significantly to 74 _+ 11% of the control value (n = 11), and the luminal over basolateral voltage divider ratio (VDR), providing an estimate of luminal over basolateral membrane resistance, decreased to 37 _ 12% of the control (n = 6). A concentration of 1 mmol/1 DNP was also applied from the lumen. The decrease in Lc was significant, but much less pronounced (74 _ 5% of control; n = 6) and no significant changes in Rte and VDR were observed. It is argued that, when the concentration in the bath is high enough, DNP may cross the cell and have a protonophoric effect not only on the mitochondria but also across the luminal cell membrane explaining the drop in transepithelial and in relative luminal membrane resistance. The diminished effectiveness of DNP, when applied from the luminal side, suggests that the luminal membrane is somehow less permeable to toxic substances, but that DNP very rapidly enters the cell via the basolateral membrane and may bring about an initial protonophoric effect across this membrane.

The purpose of the present work is to develop analytical expressions for the depth variation of the fluence, planar fluence, the energy fluence, planar energy fluence, the mean energy and absorbed dose of primary ions and their associated fragments in tissue-like media with ranges of clinical interest. The analytical expressions of the primary ions and associated fragments take into account nuclear interactions, energy losses, range straggling and multiple scattering. The analytical models of the radiation field quantities were compared with the results of the modified Monte Carlo (MC) code SHIELD-HIT(+). The results show that the shape of the depth absorbed dose distribution of the primary particles is characterized by an increasingly steep exponential fluence decrease with depth as the charge and atomic weight increase. This is accompanied by a compensating increased energy loss towards the Bragg peak as the charge of the ion increases. These largely compensating mechanisms are th...

Kinetin (N 6 -furfuryladenine) was the first cytokinin to be isolated almost 45 years ago from DNA as an artifactual rearrangement product of the autoclaving process. Since then its chemical structure and properties have been well described. Most importantly, a wide variety of biological effects of kinetin, including those on gene expression, on inhibition of auxin action, on stimulation of calcium flux, on cell cycle, and as an anti-stress and anti-ageing compound have been reported. Recently, views on this very well known plant growth factor have undergone substantial modifications. New data have appeared which show that kinetin is formed in cellular DNA as the product of the oxidative, secondary modification of DNA. Although the biological significance of the endogenous kinetin and the molecular mechanisms of its action are not completely understood at present, most of the experimental data point toward kinetin acting as a strong antioxidant in vitro and in vivo, with potential beneficial uses in agriculture and human healthcare.

Ion transport membranes (ITMs) are made from ceramic materials that conduct oxygen ions at elevated temperatures. Successful application of ITM technology will allow significant improvement in the performance of several large-scale industrial processes. The ITM Oxygen process, in which ITMs are used to separate high-purity oxygen from air, has the potential for significant advantages when integrated with power generation cycles. The ITM Syngas process, by combining air separation and high-temperature syngas generation processes into a single compact ceramic membrane reactor, has the potential for substantially reducing the capital investment for gas-to-liquid (GTL) plants and for distributed hydrogen. The development efforts are major, long-term and high risk, and place severe demands on the performance and property requirements of the ITM materials. Air Products and Chemicals has joined with the U.S. Department of Energy, Ceramatec and other partners to develop, scale-up and commercialize these technologies. In addition, Air Products and Ceramatec are developing the SEOSE Oxygen Generator, an electrically-driven, small scale, oxygen generation and removal technology using ITMs, which could have a significant impact in the global market for distributed oxygen and inert gases. This paper describes the stages of development of these three related technologies, their industrial applications, and the technical hurdles that must be overcome before successful commercialization.

The paper reviews properties of room temperature ionic liquids (RTILs) as electrolytes for lithium and lithium-ion batteries. It has been shown that the formation of the solid electrolyte interface (SEI) on the anode surface is critical to the correct operation of secondary lithium-ion batteries, including those working with ionic liquids as electrolytes. The SEI layer may be formed by electrochemical transformation of (i) a molecular additive, (ii) RTIL cations or (iii) RTIL anions. Such properties of RTIL electrolytes as viscosity, conductivity, vapour pressure and lithium-ion transport numbers are also discussed from the point of view of their influence on battery performance.

Regression analyses of major ion concentration in relation to specific conductance of water from the Mohawk River during two separate periods, 1951-53 and 1970-74, indicate statistically insignificant changes in the linear relationship of all constituents studied except chloride. Mean values and changes in the slopes of these relationships indicate that sodium and chloride have had consistently higher yields, in kilograms per square kilometer p r year, than the other ions, although all ions show a general 20 percent increase in yields during the two decades. This general increase in ion yields is attributed to an accelerated transport rate of ions out of the bash as a result of a 19 percent increase in mean stream discharge. Transport rates of sodium and chloride have increased by 72 and 145 percent, respectively, in the Mohawk River since the early 1950's. Analysis of the sodium and chloride sources indicates rock salt used as a road deicer to be the primary source. This salt use accounts for 96 percent of the sodium transport increase and 69 percent of the chloride transport increase within the basin during the last two decades. (KEY TERMS: weathering, regression analysis; water pollution;highway effects; deicing; road salt; ion transport.) 570

In the branchial mitochondrion-rich (MR) cells of euryhaline teleosts, the Na+/K+/2Cl− cotransporter (NKCC) is an important membrane protein that maintains the internal Cl− concentration, and the branchial Na+/K+-ATPase (NKA) is crucial for providing the driving force for many other ion-transporting systems. Hence this study used the sailfin molly (Poecilia latipinna), an introduced aquarium fish in Taiwan, to reveal that the potential roles of NKCC and NKA in sailfin molly were correlated to fish survival rates upon salinity challenge. Higher levels of branchial NKCC were found in seawater (SW)-acclimated sailfin molly compared to freshwater (FW)-acclimated individuals. Transfer of the sailfin molly from SW to FW revealed that the expression of the NKCC and NKA proteins in the gills was retained over 7 days in order to maintain hypoosmoregulatory endurance. Meanwhile, their survival rates after transfer to SW varied with the duration of FW-exposure and decreased significantly when the SW-acclimated individuals were acclimated to FW for 21 days. Double immunofluorescence staining showed that in SW-acclimated sailfin molly, NKCC signals were expressed on the basolateral membrane of MR cells, whereas in FW-acclimated molly, they were expressed on the apical membrane. This study illustrated the correlation between the gradual reductions in expression of branchial NKCC and NKA (i.e., the hypoosmoregulatory endurance) and decreasing survival rates after hyperosmotic challenge in sailfin molly.

The nephrotic syndrome is a frequent clinical condition characterized by fluid and salt retention. Although several theories have been put forward to explain the salt-retaining status, recent data have confirmed previous renal micropuncture observations indicating that the distal nephron is the site for increased salt reabsorption, eventually leading to sodium retention. Target proteomic approaches and immunocytochemistry experiments have identified the epithelial sodium channel (ENaC) and basolateral Na+,K+-ATPase as the main transport proteins responsible for increased transepithelial sodium reabsorption in various forms of experimental nephrotic syndrome. Although the fine-tuning for the up-regulation of these transporters has not been so far elucidated, it is clear from clinical studies that the use of amiloride, a selective, dose-dependent ENaC inhibitor, is an appropriate tool to reduce distal sodium reabsorption and thus to offset edema formation.

A new electrodynamic (rf) ion funnel has been developed and evaluated for use in the interface regions (at approximately 1-10 Torr) of atmospheric pressure ion sources (e.g., electrospray ionization (ESI) for mass spectrometry). The ion funnel consists of a ring electrode ion guide with decreasing i.d. and with a superimposed dc potential gradient along the ring stack. The thicknesses of the ring electrodes and the spacings between them were reduced to 0.5 mm from 1.59 mm compared to those used for previous designs. The new ion funnel displays a significant improvement in low-mass transmission (m/z >200) and sensitivity compared to previous designs. The transmission efficiencies for electrosprayed peptides and proteins (ranging in mass from 200 to 17,000 Da) were typically 50-60% of total incoming currents from a heated capillary inlet. The transmitted ion currents were a factor of 30-56 greater than those of the standard interface for peptide samples and a factor of 18-22 greater than those for protein samples. The sensitivity gains realized at the MS detector were somewhat lower, possibly due to space charge effects in the octapole ion beam guide following the ion funnel. The improved ion transmission properties result primarily from the use of reduced spacings between ring electrodes. We also show that the ion funnel can be operated in two different modes, one using low-rf-amplitude scans, allowing fragile noncovalent complexes (as well as generally undesired adducts) to be transmitted, and the other using high-rf-amplitude scans, providing greater collisional activation and more effective adduct removal (or the dissociation of lower m/z species).

Promising electricity and hydrogen production chains with CO 2 capture, transport and storage (CCS) and energy carrier transmission, distribution and end-use are analysed to assess (avoided) CO 2 emissions, energy production costs and CO 2 mitigation costs. For electricity chains, the performance is dominated by the impact of CO 2 capture, increasing electricity production costs with 10-40% up to 4.5-6.5 hct/kWh. CO 2 transport and storage in depleted gas fields or aquifers typically add another 0.1-1 hct/kWh for transport distances between 0 and 200 km. The impact of CCS on hydrogen costs is small. Production and supply costs range from circa 8 h/GJ for the minimal infrastructure variant in which hydrogen is delivered to CHP units, up to 20 h/GJ for supply to households. Hydrogen costs for the transport sector are between 14 and 16 h/GJ for advanced large-scale coal gasification units and reformers, and over 20 h/GJ for decentralised membrane reformers. Although the CO 2 price required to induce CCS in hydrogen production is low in comparison to most electricity production options, electricity production with CCS generally deserves preference as CO 2 mitigation option. Replacing natural gas or gasoline for hydrogen produced with CCS results in mitigation costs over 100 h/t CO 2 , whereas CO 2 in the power sector could be reduced for costs below 60 h/t CO 2 avoided. r

Although Nernst observed ionic conduction of zirconia-yttria solutions in 1899, the field of oxygen separation research remained dormant. In the last 30 years, research efforts by the scientific community intensified significantly, stemming from the pioneering work of Takahashi and co-workers, with the initial development of mixed ionic-electronic conducting (MIEC) oxides. A large number of MIEC compounds have been synthesized and characterized since then, mainly based on perovskites (ABO 3−ı and A 2 BO 4±ı ) and fluorites (A ı B 1−ı O 2−ı and A 2ı B 2−2ı O 3 ), or dual-phases by the introduction of metal or ceramic elements. These compounds form dense ceramic membranes, which exhibit significant oxygen ionic and electronic conductivity at elevated temperatures. In turn, this process allows for the ionic transport of oxygen from air due to the differential partial pressure of oxygen across the membrane, providing the driving force for oxygen ion transport. As a result, defect-free synthesized membranes deliver 100% pure oxygen. Electrons involved in the electrochemical oxidation and reduction of oxygen ions and oxygen molecules respectively are transported in the opposite direction, thus ensuring overall electrical neutrality. Notably, the fundamental application of the defect theory was deduced to a plethora of MIEC materials over the last 30 years, providing the understanding of electronic and ionic transport, in particular when dopants are introduced to the compound of interest. As a consequence, there are many special cases of ionic oxygen transport limitation accompanied by phase changes, depending upon the temperature and oxygen partial pressure operating conditions. This paper aims at reviewing all the significant and relevant contribution of the research community in this area in the last three decades in conjunction with theoretical principles.

An in vitro preparation of the dorsal epithelium of the dog tongue actively transports ions, producing a transepithelial potential difference characteristic of the ions and their concentration. Hypertonic sodium chloride solutions generally cause increased potentials and short-circuit currents and reduced resistances when placed on the mucosal surface. This hypertonic flux is eliminated by ouabain and is not found in ventral lingual epithelia. When either sodium acetate or tetramethylammonium chloride is substituted for sodium chloride in the mucosal medium, the currents are diminished but their sum at a given concentration approximates that for sodium chloride at the same concentration. This result suggests a current composed of inward sodium ion movement and outward chloride ion movement. Actively regulated potentials and currents, whether generated in the taste buds or in supporting cells, may be important in both normal chemotransduction and in taste responses evoked by currents passing through the tongue.

This paper describes the corrosion behaviour of the positive and negative electrodes of a lead-acid battery in 5 M H 2 SO 4 with binary additives such as mixtures of phosphoric acid and boric acid, phosphoric acid and tin sulphate, and phosphoric acid and picric acid. The effect of these additives is examined from the Tafel polarisation curves, double layer capacitance and percentage of inhibition efficiency. A lead salt battery has been fabricated replacing the binary mixture with an alternative electrolyte and the above electrochemical parameters have been evaluated for this lead salt battery. The results are explained in terms of H þ ion transport and the morphological change of the PbSO 4 layer.

Printed circuit board (PCB) specimens containing three different IPC-B-25 test structures were exposed to temperature/humidity/bias conditions in order to evaluate the effects of conformal coating, conductor spacing, voltage bias, flux chemistry, and test environment on surface insulation resistance (SIR). Results indicate that conformal coatings improve reliability, provided that sources of contamination on the PCB and within the coating are minimized. The presence of fibrous contaminants within the coating represented a preferential medium for moisture adsorption and ion transport, leading to accelerated reduction of SIR. In the absence of contamination, PCBs with conformal coatings were found to be less susceptible to SIR degradation than uncoated PCBs, with silicone providing better protection than urethane, and acrylic providing the least protection of the three coating materials evaluated. Conductor spacing was observed to represent a factor in the electrochemical migration (ECM) process independent of electric field, indicating that updated test structures are required to predict reliability of today's high-density assemblies. The SIR failure rate with rosin-based no-clean flux was observed to be greater than that with aqueous-based no-clean flux. A higher failure rate was also observed for tests conducted at 40 C/93% RH than for 85 C/85% RH. Due to the more rapid evaporation of weak organic acids in the flux residues at higher temperatures, test results obtained at 85 C/85% RH will not accurately predict reliability at lower temperatures for PCBs processed using no-clean flux. PCB specimens were exposed to temperature/humidity/bias conditions in order to evaluate the effects of conformal coating, conductor spacing, voltage bias, flux chemistry, and test environment on reduction of surface insulation resistance. Results indicate that, in the absence of contamination, conformal coatings improve reliability.

Transient waves of Ca 2/ release cross-fertilizing deuterostome eggs from the point of sperm entry to its antipode and provide much of the activating stimulus for the egg. Based on several indirect lines of experimental evidence, it was proposed that protostome eggs are activated by a prolonged uptake of Ca 2/ from the medium due to sperm-induced membrane depolarization and that this uptake then starts an activation wave similar to those in deuterostomes, except that it moves inward from the whole surface rather than through the egg from pole to pole. To test these hypotheses, we microinjected oocytes of the polychaete annelid, Chaetopterus pergamentaceus, with semisynthetic recombinant aequorins and measured light emission in response to both fertilization and artificial activation by excess K / . Both fertilization and K / -activation induced multiple, brief Ca 2/ transients in the eggs. The first transient did not propagate, but it was followed by a series of globally propagated Ca 2/ waves interspersed with additional nonpropagated pulses. The waves traversed the egg at about 30 mm/sec. Sequential propagated waves and nonpropagated pulses generally originated at different regions on the egg surface, except the last few, which originated in the same ''pacemaker'' region. These new data are consistent with the hypothesis that the activation of protostome eggs is initiated by Ca 2/ waves. However, the fact that these waves propagated from pole to pole like those in deuterostome eggs refutes the notion that Ca 2/ waves in activating protostome eggs move inward from the whole surface. ᭧ 1995 Academic Press, Inc.

The maintenance of pH homeostasis in the CNS is of key importance for proper execution and regulation of neurotransmission, and deviations from this homeostasis are a crucial factor in the mechanism underlying a spectrum of pathological conditions. The first few sections of the review are devoted to the brain operating under normal conditions. The article commences with an overview of how extrinsic factors modelling the brain at work: neurotransmitters, depolarising stimuli (potassium and voltage changes) and cyclic nucleotides as major signal transducing vehicles affect pH in the CNS. Further, consequences of pH alterations on the major aspects of CNS function and metabolism are outlined. Next, the major cellular events involved in the transport, sequestration, metabolic production and buffering of protons that are common to all the mammalian cells, including the CNS cells. Since CNS function reflects tight interaction between astrocytes and neurons, the pH regulatory events pertinent to either cell type are discussed: overwhelming evidence implicates astrocytes as a key player in pH homeostasis in the brain. The different classes of membrane proteins involved in proton shuttling are listed and their mechanisms of action are given. These include: the Na+/H+ exchanger, different classes of bicarbonate transporters acting in a sodium-dependent- or -independent mode, monocarboxylic acid transporters and the vacuolar-type proton ATPase. A separate section is devoted to carbonic anhydrase, which is represented by multiple isoenzymes capable of pH buffering both in the cell interior and in the extracellular space. Next, impairment of pH regulation and compensatory responses occurring in brain affected by different pathologies: hypoxia/ischemia, epilepsy, hyperammonemic encephalopathies, cerebral tumours and HIV will be described. The review is limited to facts and plausible hypotheses pertaining to phenomena directly involved in pH regulation: changes in pH that accompany metabolic stress but have no distinct implications for the pH regulatory mechanisms are not dealt with. In most cases, the vast body of knowledge derived from in vitro studies remains to be verified in in vivo settings.

Drought, salinity and extreme temperature are major adverse environmental factors that limit plant productivity. Sensors initiate a signaling cascade to transmit the signal and activate nuclear transcription factors to induce the expression of specific sets of genes. Ionic and osmotic stress signal transduction triggers the ionic and osmotic homeostasis signaling pathways, detoxification response pathways, and pathways for growth regulation. The ionic stress is signaled via the SOS pathway where an SOS3-SOS2 complex controls the expression and activity of ion transporters. Osmotic stress activates several protein kinases which mediate osmotic homeostasis and/or detoxification responses. Understanding the mechanisms by which plants perceive and transduce the stress signals to initiate adaptive responses is essential for engineering stress-tolerant crop plants. Genetic engineering strategies rely on the transfer of one or several genes that are either involved in signaling and regulatory pathways, or that encode enzymes present in pathways leading to the synthesis of functional and structural protectants, or that encode stresstolerance-conferring proteins. Certain techniques have been described to identify the gene whose expression is differentially regulated in response to various environmental stresses in higher plants. Such methods include differential display-polymerase chain reaction, suppression subtractive hybridization, serial analysis of gene expression, DNA microarray and cDNA-amplified fragment length polymorphism.

Data are accumulating that emphasize the important role of the intestinal barrier and intestinal permeability for health and disease. However, these terms are poorly defined, their assessment is a matter of debate, and their clinical significance is not clearly established. In the present review, current knowledge on mucosal barrier and its role in disease prevention and therapy is summarized. First, the relevant terms 'intestinal barrier' and 'intestinal permeability' are defined. Secondly, the key element of the intestinal barrier affecting permeability are described. This barrier represents a huge mucosal surface, where billions of bacteria face the largest immune system of our body. On the one hand, an intact intestinal barrier protects the human organism against invasion of microorganisms and toxins, on the other hand, this barrier must be open to absorb essential fluids and nutrients. Such opposing goals are achieved by a complex anatomical and functional structure the intestinal barrier consists of, the functional status of which is described by 'intestinal permeability'. Third, the regulation of intestinal permeability by diet and bacteria is depicted. In particular, potential barrier disruptors such as hypoperfusion of the gut, infections and toxins, but also selected over-dosed nutrients, drugs, and other lifestyle factors have to be considered. In the fourth part, the means to assess intestinal permeability are presented and critically discussed. The means vary enormously and probably assess different functional components of the barrier. The barrier assessments are further hindered by the natural variability of this functional entity depending on species and genes as well as on diet and other environmental factors. In the final part, we discuss selected diseases associated with increased intestinal permeability such as critically illness, inflammatory bowel diseases, celiac disease, food allergy, irritable bowel syndrome, andmore recently recognizedobesity and metabolic diseases. All these diseases are characterized by inflammation that might be triggered by the translocation of luminal components into the host. In summary, intestinal permeability, which is a feature of intestinal barrier function, is increasingly recognized as being of relevance for health and disease, and therefore, this topic warrants more attention.

With recent advancements in DNA-chip technology, requisite software development and support and progress in related aspects of plant molecular biology, it is now possible to comprehensively analyze the expression of complete genomes. Global transcript profiling shows that in plants, salt-stress response involves simultaneous up and downregulation of a large number of genes. This analysis further suggests that apart from the transcripts that govern synthesis of osmolytes and ion transporters, two candidate systems that have attracted much of the attention thus far, transcripts encoding for proteins related to the regulation of transcriptional and translational machineries have a distinct role in salt-stress response. In particular, induction of transcripts of specific transcription factors, RNA-binding proteins, ribosomal genes, and translation initiation and elongation factors has recently been noted to be important during salt stress. There is an urgent need to examine cellular functionality of the above putative salt-tolerance-related genes emerging from the transcriptome analysis.