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1
Liu, Dan, and Ling-Qiang Zhu. "P3-224: GSK-3 activation retards the axonal transport." Alzheimer's & Dementia 7 (July 2011): S587. http://dx.doi.org/10.1016/j.jalz.2011.05.1666.
2
Chen, Ru, James C. McWilliams, and Lionel Renault. "Momentum Governors of California Undercurrent Transport." Journal of Physical Oceanography 51, no. 9 (September 2021): 2915–32. http://dx.doi.org/10.1175/jpo-d-20-0234.1.
Анотація:
AbstractThe California Undercurrent (CUC) transport, with significant variability ranging from weeks to decades, has consequences for both the climate and biogeochemistry of the California Current system. This study evaluates the governors of the CUC transport and its temporal variability from a momentum perspective, using a mesoscale-resolving regional model. From a 16-yr mean perspective, the along-isobath pressure gradient acts to accelerate the CUC, whereas eddy advection retards it. The topographic form stress, which is part of the volume integrated along-isobath pressure gradient, not only acts in the direction of the time-mean CUC, but also greatly modulates the temporal variability of the CUC transport. This temporal variability is also correlated with the eddy momentum advection. The eddy stress plays a role in transferring both the equatorward wind stress and poleward CUC momentum downward. A theory is formulated to show that, in addition to the conventional vertical redistribution of momentum, the eddy stress can also redistribute momentum horizontally in the area where the correlation between the pressure anomaly and isopycnal fluctuations has large spatial variability.
3
Friederich, E., H. J. Fritz, and W. B. Huttner. "Inhibition of tyrosine sulfation in the trans-Golgi retards the transport of a constitutively secreted protein to the cell surface." Journal of Cell Biology 107, no. 5 (November 1, 1988): 1655–67. http://dx.doi.org/10.1083/jcb.107.5.1655.
Анотація:
The effect of tyrosine sulfation on the transport of a constitutively secreted protein, yolk protein 2 (YP2) of Drosophila melanogaster, to the cell surface was investigated after expression of YP2 in mouse fibroblasts. Inhibition of YP2 sulfation was achieved by two distinct approaches. First, the single site of sulfation in YP2, tyrosine 172, was changed to phenylalanine by oligonucleotide-directed mutagenesis. Second, L cell clones stably expressing YP2 were treated with chlorate, a reversible inhibitor of sulfation. Pulse-chase experiments with transfected L cell clones showed that the half-time of transport from the rough endoplasmic reticulum to the cell surface of the unsulfated mutant YP2 and the unsulfated wild-type YP2 produced in the presence of chlorate was 15-18 min slower than that of the sulfated wild-type YP2. Control experiments indicated (a) that the tyrosine to phenylalanine change itself did not affect YP2 transport, (b) that the retardation of YP2 transport by chlorate occurred only with sulfatable but not with unsulfatable YP2, (c) that the transport difference between wild-type and mutant YP2 was not due to the level of YP2 expression, and (d) that transport of the endogenous secretory protein fibronectin was the same in L cell clones expressing wild-type and mutant YP2. Since the half-time of transport of wild-type YP2 from the intracellular site of sulfation, the trans-Golgi, to the cell surface was found to be 10 min, the 15-18-min retardation seen upon inhibition of tyrosine sulfation reflected a two- to threefold increase in the half-time of trans-Golgi to cell surface transport, which was most probably caused by an increased residence time of unsulfated YP2 in the trans-Golgi. The results demonstrate a role of tyrosine sulfation in the intracellular transport of a constitutively secreted protein.
4
Ebneth, A., R. Godemann, K. Stamer, S. Illenberger, B. Trinczek, E. M. Mandelkow, and E. Mandelkow. "Overexpression of Tau Protein Inhibits Kinesin-dependent Trafficking of Vesicles, Mitochondria, and Endoplasmic Reticulum: Implications for Alzheimer's Disease." Journal of Cell Biology 143, no. 3 (November 2, 1998): 777–94. http://dx.doi.org/10.1083/jcb.143.3.777.
Анотація:
The neuronal microtubule-associated protein tau plays an important role in establishing cell polarity by stabilizing axonal microtubules that serve as tracks for motor-protein–driven transport processes. To investigate the role of tau in intracellular transport, we studied the effects of tau expression in stably transfected CHO cells and differentiated neuroblastoma N2a cells. Tau causes a change in cell shape, retards cell growth, and dramatically alters the distribution of various organelles, known to be transported via microtubule-dependent motor proteins. Mitochondria fail to be transported to peripheral cell compartments and cluster in the vicinity of the microtubule-organizing center. The endoplasmic reticulum becomes less dense and no longer extends to the cell periphery. In differentiated N2a cells, the overexpression of tau leads to the disappearance of mitochondria from the neurites. These effects are caused by tau's binding to microtubules and slowing down intracellular transport by preferential impairment of plus-end–directed transport mediated by kinesin-like motor proteins. Since in Alzheimer's disease tau protein is elevated and mislocalized, these observations point to a possible cause for the gradual degeneration of neurons.
5
Blostein, Rhoda, and Eva Grafova. "Characteristics of membrane transport losses during reticulocyte maturation." Biochemistry and Cell Biology 65, no. 10 (October 1, 1987): 869–75. http://dx.doi.org/10.1139/o87-113.
Анотація:
The decline in activity of distinct membrane transport systems was followed during in vitro maturation of sheep reticulocytes, namely the sodium pump (measured as specific ouabain binding sites), Na+–glycine cotransport, and the nucleoside transporter (measured as specific nitrobenzylthioinosine binding sites). Certain features of this maturation-associated decline in membrane transport are clarified. Thus, the apparent retardation of loss by metabolic (ATP) depletion, reported previously for the sodium pump and Na+–glycine cotransport, is applicable also to the decline in nucleoside transport. The absolute losses, as well as relative effects of ATP depletion, are different for the three distinct systems. Inhibitors of membrane recycling and (or) intracellular processing, such as chloroquine, as well as ATP depletion, prevent not only the loss but also cause a transient increase in nucleoside transport sites apparent at the surface. Proteolytic processing, at least in the case of the nucleoside transporter, is probably also involved since leupeptin retards the loss in binding sites. Protection against the decline in transporters can also be affected by specific ligands as evidenced in ouabain protection of sodium pump sites. The results provide evidence that membrane transporter recycling is a fundamental process underlying the energy-dependent, maturation-associated loss in membrane transport functions.
6
Nicot, Benjamin, Jean-Pierre Korb, Isabelle Jolivet, Hervé Vezin, Didier Gourier, and Anne-Laure Rollet. "Magnetic expression in kerogen reveals impact on fluid transport." Magnetic Resonance 3, no. 2 (July 29, 2022): 125–36. http://dx.doi.org/10.5194/mr-3-125-2022.
Анотація:
Abstract. How can the transport of fluids in a confined and complex mixed organic/inorganic matrix be far below the expected value from a topological aspect? A good example of this situation is oil shales. Oil and gas shales are source rocks in which organic matter has matured to form hydrocarbons. They exhibit a dual porous network formed by the intertwining of mineral and organic pores that leads to very low permeability. Still, the exact origin of this extremely low permeability remains somehow unclear. The present communication addresses this important question and provides novel insights on the mechanisms that strongly hinder fluid diffusion in such materials. By combining nuclear and electronic magnetic resonance techniques with SEM imaging, we show evidence that magnetic interaction occurs in kerogen. This results from a magnetic coupling between vanadyl present in porphyrins and the organic matrix. We demonstrate that such coupling retards fluid diffusion and is reversible. This key dynamical feature explains the extremely low mobility of oil in shale rocks. This phenomenon may be a more general feature occurring in several systems where fluids are confined in a complex hierarchical matrix that embeds both organic and inorganic radicals resulting from the aging process.
7
Casirola, D. M., B. Rifkin, W. Tsai, and R. P. Ferraris. "Adaptations of intestinal nutrient transport to chronic caloric restriction in mice." American Journal of Physiology-Gastrointestinal and Liver Physiology 271, no. 1 (July 1, 1996): G192—G200. http://dx.doi.org/10.1152/ajpgi.1996.271.1.g192.
Анотація:
Lifelong caloric restriction increases median and maximum life span and retards the aging process in many organ systems of rodents. Because the small intestine absorbs a reduced amount of nutrients each day, does lifelong caloric restriction induce adaptations in intestinal nutrient transport? We initially compared intestinal transport of sugars and amino acids between 24-mo-old mice allowed free access to food [ad libitum (AL)] and those provided a calorically restricted [40% less than ad libitum (CR)] diet since 3 mo of age. We found that CR mice had significantly greater transport rates for D-glucose, D-fructose, and several amino acids and had significantly lower villus heights. Total intestinal absorptive capacities for D-glucose, D-fructose, and L-proline were each 40-50% greater in CR mice; absorptive capacity normalized to metabolic mass (body weight 0.75) was approximately 80% greater in CR mice. Comparison of uptakes in aged AL and CR mice with previously published results in young AL mice suggests that caloric restriction delays age-related decreases in nutrient transport. In contrast to published studies in hibernation and starvation, chronic caloric restriction enhances not only uptake per milligram but also uptake per centimeter. We then switched 24-mo-old AL mice to a calorie-restricted diet for 1 mo and found that short-term caloric restriction has no effect on intestinal nutrient transport, intestinal mass, and total absorptive capacity. Thus chronic but not short-term caloric restriction increases intestinal nutrient transport rates in aged mice, and the main mechanism underlying these increases is enhanced transport rates per unit intestinal tissue weight.
8
Zhu, Qinzhang, Michael Lindenbaum, Françoise Levavasseur, Hélène Jacomy та Jean-Pierre Julien. "Disruption of the NF-H Gene Increases Axonal Microtubule Content and Velocity of Neurofilament Transport: Relief of Axonopathy Resulting from the Toxin β,β′-Iminodipropionitrile". Journal of Cell Biology 143, № 1 (5 жовтня 1998): 183–93. http://dx.doi.org/10.1083/jcb.143.1.183.
Анотація:
To investigate the role of the neurofilament heavy (NF-H) subunit in neuronal function, we generated mice bearing a targeted disruption of the gene coding for the NF-H subunit. Surprisingly, the lack of NF-H subunits had little effect on axonal calibers and electron microscopy revealed no significant changes in the number and packing density of neurofilaments made up of only the neurofilament light (NF-L) and neurofilament medium (NF-M) subunits. However, our analysis of NF-H knockout mice revealed an ∼2.4-fold increase of microtubule density in their large ventral root axons. This finding was further corroborated by a corresponding increase in the ratio of assembled tubulin to NF-L protein in insoluble cytoskeletal preparations from the sciatic nerve. Axonal transport studies carried out by the injection of [35S]methionine into spinal cord revealed an increased transport velocity of newly synthesized NF-L and NF-M proteins in motor axons of NF-H knockout mice. When treated with β,β′-iminodipropionitrile (IDPN), a neurotoxin that segregates microtubules and retards neurofilament transport, mice heterozygous or homozygous for the NF-H null mutation did not develop neurofilamentous swellings in motor neurons, unlike normal mouse littermates. These results indicate that the NF-H subunit is a key mediator of IDPN-induced axonopathy.
9
Fiermonte, G., J. E. Walker, and F. Palmieri. "Abundant bacterial expression and reconstitution of an intrinsic membrane-transport protein from bovine mitochondria." Biochemical Journal 294, no. 1 (August 15, 1993): 293–99. http://dx.doi.org/10.1042/bj2940293.
Анотація:
The oxoglutarate carrier, an intrinsic membrane-transport protein of the inner membranes of bovine-heart mitochondria, has been expressed at an abundant level in Escherichia coli. It accumulates in the bacterium as inclusion bodies, and none of the protein was detected in the bacterial inner membrane. The mitochondrial ADP/ATP carrier, a member of the same super-family of transport proteins as the oxoglutarate carrier, has also been expressed in E. coli. However, the expression of the ADP/ATP carrier in bacteria retards their growth, and so the levels of expression that were attained were lower than those of the oxoglutarate carrier. The oxoglutarate carrier inclusion bodies have been disaggregated with the detergent N-dodecanoyl-sarcosine, and the protein has been incorporated into liposomes. In its ability to transport oxoglutarate and malate and other known substrates of the carrier in mitochondria, and in its inhibition characteristics by a wide range of non-competitive and competitive inhibitors, this reconstituted oxoglutarate carrier is similar to the natural protein in the inner membranes of mitochondria, and to the carrier that has been purified from mitochondria and reconstituted in liposomes. These experiments remove significant obstacles to crystallization trials and to site-directed mutagenesis of the oxoglutarate carrier.
10
Yang, Y. Q., and J. T. Wu. "RU 486 interferes with egg transport and retards the in vivo and in vitro development of mouse embryos." Contraception 41, no. 5 (May 1990): 551–56. http://dx.doi.org/10.1016/0010-7824(90)90063-2.
11
Berisha, Avni, Fetah Podvorica, Valbonë Mehmeti, Fidan Syla, and Debatik Vataj. "Theoretical and experimental studies of the corrosion behavior of some thiazole derivatives toward mild steel in sulfuric acid media." Macedonian Journal of Chemistry and Chemical Engineering 34, no. 2 (November 12, 2015): 287. http://dx.doi.org/10.20450/mjcce.2015.576.
Анотація:
<p>The corrosion behavior of iron in diluted aqueous sulfuric acid medium has been studied in the presence and absence of 6-ethoxybenzo[<em>d</em>]thiazol-2-amine (EBT), 5-bromothiazol-2-amine (BTA) and 4,5-dimethylthiazol-2-amine (DTA). Potentiodynamic measurements showed the shift of corrosion potential towards a more negative potential indicating that these compounds mostly act as cathodic inhibitors due to their adsorption on the iron surface. The adsorbed film of these molecules hinders the transport of metal ions from the metal to the solution and also retards hydrogen evolution reaction by acting as a physical barrier. The molecules were also studied by density functional theory (DFT), using the B3LYP functional in order to determine the relationship between molecular structure and the corrosion inhibition efficiencies.</p>
12
An, Lihong, Guozhen Li, Jiliang Si, Cuili Zhang, Xiaoying Han, Shuo Wang, Lulu Jiang, and Keqin Xie. "Acrylamide Retards the Slow Axonal Transport of Neurofilaments in Rat Cultured Dorsal Root Ganglia Neurons and the Corresponding Mechanisms." Neurochemical Research 41, no. 5 (December 31, 2015): 1000–1009. http://dx.doi.org/10.1007/s11064-015-1782-z.
13
Engel, Stephanie, Maren de Vries, Andreas Herrmann, and Michael Veit. "Mutation of a raft-targeting signal in the transmembrane region retards transport of influenza virus hemagglutinin through the Golgi." FEBS Letters 586, no. 3 (January 10, 2012): 277–82. http://dx.doi.org/10.1016/j.febslet.2012.01.002.
14
Prasad, V. Ramachandra, R. Bhuvanavijaya, and Mallikarjuna Bandaru. "Natural convection on heat transfer flow of non-newtonian second grade fluid over horizontal circular cylinder with thermal radiation." Journal of Naval Architecture and Marine Engineering 13, no. 1 (June 15, 2016): 63–78. http://dx.doi.org/10.3329/jname.v13i1.20703.
Анотація:
This article numerically studies for multi-physical transport of an optically-dense, free convective incompressible non-Newtonian second grade fluid past an isothermal, impermeable horizontal circular cylinder. The governing boundary layer equations for momentum and energy transport, which are parabolic in nature, have been reduced to non-similarity non-linear conservation equations using appropriate transformations and then solved numerically by employing with most validated, efficient implicit finite difference method with Keller box scheme. The numerical code is validated with previously existing results and found to be very good agreement. The results are reported graphically and in tabular form for various physical parameters; Deborah number, Prandtl number and thermal radiation on flow velocity and temperature profiles. Furthermore, the effects of these parameters on non dimensional wall shear stress (skin friction) and surface heat transfer rate (Nusselt number) are also investigated. Increasing the Deborah number reduces velocity profile, skin friction and Nusselt number where as it enhances the temperature profile. Increasing Prandtl number decelerates the flow velocity, temperature and skin friction but Nusselt number enhances considerably. Increase in radiation parameter retards the flow velocity, temperature profiles and skin friction. But Nusselt number enhances markedly with increase in radiation parameter. Applications of the model arise in polymer processing in chemical engineering, metallurgical material processing.
15
Pandey, Prem, Shubhangi Shukla, Shelby Skoog, Ryan Boehm, and Roger Narayan. "Current Advancements in Transdermal Biosensing and Targeted Drug Delivery." Sensors 19, no. 5 (February 28, 2019): 1028. http://dx.doi.org/10.3390/s19051028.
Анотація:
In this manuscript, recent advancements in the area of minimally-invasive transdermal biosensing and drug delivery are reviewed. The administration of therapeutic entities through the skin is complicated by the stratum corneum layer, which serves as a barrier to entry and retards bioavailability. A variety of strategies have been adopted for the enhancement of transdermal permeation for drug delivery and biosensing of various substances. Physical techniques such as iontophoresis, reverse iontophoresis, electroporation, and microneedles offer (a) electrical amplification for transdermal sensing of biomolecules and (b) transport of amphiphilic drug molecules to the targeted site in a minimally invasive manner. Iontophoretic delivery involves the application of low currents to the skin as well as the migration of polarized and neutral molecules across it. Transdermal biosensing via microneedles has emerged as a novel approach to replace hypodermic needles. In addition, microneedles have facilitated minimally invasive detection of analytes in body fluids. This review considers recent innovations in the structure and performance of transdermal systems.
16
DiCarlantonio, G., and P. Talbot. "Inhalation of Mainstream and Sidestream Cigarette Smoke Retards Embryo Transport and Slows Muscle Contraction in Oviducts of Hamsters (Mesocricetus auratus)1." Biology of Reproduction 61, no. 3 (September 1, 1999): 651–56. http://dx.doi.org/10.1095/biolreprod61.3.651.
17
Coulson, R., P. S. Proch, R. A. Olsson, C. E. Chalfant, and D. R. Cooper. "Upregulated renal adenosine A1 receptors augment PKC and glucose transport but inhibit proliferation." American Journal of Physiology-Renal Physiology 270, no. 2 (February 1, 1996): F263—F274. http://dx.doi.org/10.1152/ajprenal.1996.270.2.f263.
Анотація:
Adenosine A1 receptor densities were increased in cultured LLC-PK1 and OK cells by chronic treatment with the adenosine receptor antagonists 1,3,7-trimethylxanthine (caffeine, 1 mM) and 1,3-dimethyl-8-cyclopentylxanthine [cyclopentyltheophylline (CPT), < or = 0.4 mM], respectively. The A1 receptor number per cell was increased twofold by 10-day treatments with 1 mM caffeine or 0.1 mM CPT, and the sodium-coupled glucose uptake was augmented twofold by 1 mM caffeine and sevenfold by 0.1 microM CPT (higher doses of CPT were progressively less stimulatory). Glucose uptake was blocked by acute (2-h) treatment with CPT, adenosine deaminase, or calphostin C. Caffeine (1 mM) or CPT (> or = 0.1 mM) inhibited cell proliferation for the first 10 days, then cell growth assumed a normal proliferative rate despite continued presence of antagonist. Cytosolic protein kinase C (PKC) beta-isoform immunoactivity and PKC-beta II mRNA were elevated at least twofold during 10 days of 0.1 mM CPT or 1 mM caffeine treatment. The sustained elevation in sodium-glucose symport and PKC activity observed with adenosine receptor antagonists was similar to acute (2-h) effects of the adenosine A1 agonist R(-)-N6-phenylisopropyladenosine (R-PIA, 0.1-1 microM). Moreover, cell proliferation was increased by adenosine (0.1 microM R-PIA), whereas Na-K-adenosinetriphosphatase activity was unaltered with chronic antagonist or acute adenosine treatments. Caffeine treatment may have some non-adenosine A1 receptor-mediated actions, because it slightly (30%) augmented protein kinase A activity. It is concluded that chronic exposure of proximal tubule cells to caffeine or CPT augments PKC and sodium-glucose transport but retards cell proliferation mainly via adenosine A1 receptor-mediated mechanisms.
18
Vautier, D., P. Chesne, C. Cunha, A. Calado, J. P. Renard, and M. Carmo-Fonseca. "Transcription-dependent nucleocytoplasmic distribution of hnRNP A1 protein in early mouse embryos." Journal of Cell Science 114, no. 8 (April 15, 2001): 1521–31. http://dx.doi.org/10.1242/jcs.114.8.1521.
Анотація:
A unique feature of certain members of the heterogeneous nuclear ribonucleoprotein (hnRNP) family of proteins is that they shuttle continuously between nucleus and cytoplasm and their accumulation in the nucleus is transcription-dependent. An extensively characterised protein of this group is hnRNP A1. To date, most studies addressing the transcription-dependent transport of hnRNP A1 have been performed on cultured cell lines treated with transcription inhibitors. Here we have analysed the nucleocytoplasmic distribution of hnRNP A1 in early mouse embryos, where the haploid pronuclei remain transcriptionally inactive for a period of several hours. Consistent with its small molecular size (36 kDa), the hnRNP A1 protein diffuses passively through the nuclear pores and equilibrates between the nucleus and the cytoplasm of transcriptionally inactive embryos. In contrast, following transcriptional activation the A1 protein becomes accumulated in the nucleus. This accumulation of the A1 protein in the nucleus is blocked by the lectin wheat germ agglutinin (WGA), which binds to nuclear pore proteins and prevents translocation of receptor-cargo complexes through the pores. This indicates that a carrier-mediated transport pathway is required for the concentration of A1 in transcriptionally active nuclei. To further analyse how transcription is coupled to nucleocytoplasmic transport, we transplanted transcriptionally inactive pronuclei into the cytoplasm of transcriptionally active embryos. The results show that the presence of newly synthesised RNAs in the cytoplasm is not sufficient to induce the accumulation of hnRNP A1 in the nucleus. Rather, the appearance of nascent transcripts in the nucleus appears to be the crucial event. Since hnRNP A1 is a shuttling protein, an increase in its steady state nuclear concentration could be the result of either faster nuclear import or slower export to the cytoplasm. We propose that binding of A1 to nascent transcripts retards its export to the cytoplasm and therefore contributes to its concentration in the nucleus.
19
Altundas, Y. B. B., T. S. S. Ramakrishnan, Nikita Chugunov, and Romain de Loubens. "Retardation of CO2 Caused by Capillary Pressure Hysteresis: A New CO2 Trapping Mechanism." SPE Journal 16, no. 04 (November 10, 2011): 784–94. http://dx.doi.org/10.2118/139641-pa.
Анотація:
Summary Containment security of geologically stored CO2 is improved substantially through trapping mechanisms. Therefore, to simulate the potential viability of a storage site, it is necessary to account for immobilization processes. In this paper, we focus on a quantitative measure for the contribution of hysteresis in reducing plume transport, with particular emphasis on capillary-pressure-induced migration retardation. Rocks with large pore-body-to-throat-size ratio, or a low permeability, are the best candidates for this mechanism to be operative. In the present work, a self-consistent relative permeability and capillary pressure hysteresis model is incorporated within a simulator. With this model, it is possible to compare and contrast hysteresis-induced retardation to other mechanisms of trapping. The self-consistent parameterization of all of the transport properties is used to quantify sensitivity compactly. The sensitivity of the CO2-plume shape and the amount of CO2 trapped to the strength of the capillary pressure hysteresis is also described. Simulated results show that the CO2-plume shapes with and without capillary pressure hysteresis are significantly different. As expected, capillary pressure hysteresis retards the buoyant transport of the CO2 plume. Although a portion of the CO2 is connected, and therefore not residual, the plume remains immobile for all practical purposes. Also, because of the decreased driving potential, gravity tonguing below the caprock is reduced in comparison to the case without capillary pressure hysteresis, thus suggesting enhanced storage efficiency. However, the total dissolution of CO2 in saline water is reduced because of the reduced contact area with the brine. Thus, one mechanism of containment is offset by the other. Inclusion of accurate hysteresis models is important for qualifying storage sites constrained by spatial-domain limits. It is anticipated that site-acceptability criteria would change as a result of this study, thereby impacting risk evaluation.
20
Wegner, Lars H. "A pump/leak model of growth: the biophysics of cell elongation in higher plants revisited." Functional Plant Biology 44, no. 2 (2017): 185. http://dx.doi.org/10.1071/fp16184.
Анотація:
Current concepts of growth hydraulics in higher plants are critically revisited, and it is concluded that they partly fail to interpret the experimental data adequately, particularly in the case of hydroponics-grown roots. Theoretical considerations indicate that the growth rate in roots is controlled by the extensibility of the cell wall, excluding water availability (i.e. hydraulic conductance) as a major constraint. This is supported by the findings that the growth rate does not scale with turgor, and that no radial nor axial water potential gradients have been observed in the root elongation zone. Nevertheless, a water potential deficit ranging from –0.2 to –0.6 MPa has repeatedly been reported for growing cells that by far exceeds the shallow trans-membrane water potential difference required for the uptake of growth water. Unexpectedly, growth was also shown to depend on the hydraulic conductance (LP) of the plasma membrane of root cells, even though LP should generally be too large to have an impact on growth. For leaves, similar observations have been reported, but the interpretation of the data is less straightforward. Inconsistencies associated with the current model of growth hydraulics prompt the author to suggest a revised model that comprises, in addition to a passive mechanism of water transport across the plasma membrane of growing cells mediated by aquaporins (‘leak’) a secondary active water transport (‘pump’), in analogy to a mechanism previously demonstrated for mammalian epithelia and postulated for xylem parenchyma cells in roots. Water is hypothesised to be secreted against a trans-membrane water potential difference by cotransport with solutes (salts, sugars, and/or amino acids), taking advantage of the free energy released by this transport step. The solute concentration gradient is supposed to be maintained by a subsequent retrieval of the solutes from the apoplast and back-transport at the expense of metabolic energy. Water secretion tends to reduce the turgor pressure and retards growth, but turgor and, in turn, growth can be upregulated very rapidly independent from any adjustment in the osmolyte deposition rate by increasing LP and/or reducing secondary active water transport, e.g. when the root is exposed to mild osmotic stress, as confirmed by experimental studies.
21
Medraño-Fernandez, Iria, Claudio Fagioli, Alexandre Mezghrani, Mieko Otsu, and Roberto Sitia. "Different redox sensitivity of endoplasmic reticulum associated degradation clients suggests a novel role for disulphide bonds in secretory proteins." Biochemistry and Cell Biology 92, no. 2 (April 2014): 113–18. http://dx.doi.org/10.1139/bcb-2013-0090.
Анотація:
To maintain proteostasis in the endoplasmic reticulum (ER), terminally misfolded secretory proteins must be recognized, partially unfolded, and dislocated to the cytosol for proteasomal destruction, in a complex process called ER-associated degradation (ERAD). Dislocation implies reduction of inter-chain disulphide bonds. When in its reduced form, protein disulphide isomerase (PDI) can act not only as a reductase but also as an unfoldase, preparing substrates for dislocation. PDI oxidation by Ero1 favours substrate release and transport across the ER membrane. Here we addressed the redox dependency of ERAD and found that DTT stimulates the dislocation of proteins with DTT-resistant disulphide bonds (i.e., orphan Ig-μ chains) but stabilizes a ribophorin mutant (Ri332) devoid of them. DTT promotes the association of Ri332, but not of Ig-µ, with PDI. This discrepancy may suggest that disulphide bonds in cargo proteins can be utilized to oxidize PDI, hence facilitating substrate detachment and degradation also in the absence of Ero1. Accordingly, Ero1 silencing retards Ri332 degradation, but has little if any effect on Ig-µ. Thus, some disulphides can increase the stability and simultaneously favour quality control of secretory proteins.
22
Powell, J. J., R. Jugdaohsingh, and R. P. H. Thompson. "The regulation of mineral absorption in the gastrointestinal tract." Proceedings of the Nutrition Society 58, no. 1 (February 1999): 147–53. http://dx.doi.org/10.1079/pns19990020.
Анотація:
The absorption of metal ions in the mammalian single-stomached gut is fortunately highly selective, and both luminal and tissue regulation occur. Initially, assimilation of metal ions in an available form is facilitated by the intestinal secretions, chiefly soluble mucus (mucin) that retards hydrolysis of ions such as Cu, Fe and Zn. Metal ions then bind and traverse the mucosally-adherent mucus layer with an efficiency M+> M2+> M3+. At the mucosa Fe3+is probably uniquely reduced to Fe2+, and all divalent cations (including Fe2+) are transported by a membrane protein (such as divalent cation transporter 1) into the cell. This minimizes absorption of toxic trivalent metals (e.g. A13+). Intracellular metal-binding molecules (such as mobilferrin) may be present at the intracellular side of the apical membrane, anchored to a transmembrane protein such as an integrin complex. This mobilferrin would receive the metal ion from divalent cation transporter 1 and, with part of the integrin molecule, transport the metal to the cytosol for safe sequestration in a larger complex such as ferritin or‘paraferritin’. β2-Microglobulin and HFE (previously termed human leucocyte antigen H) may be involved in stabilizing metal mobilferrin-integrin to form this latter complex. Finally, a systemic metal-binding protein such as transferrin may enter the antiluminal (basolateral) side of the cell for binding of the sequestered metal ion and delivery to the circulation. Regulatory proteins, such as HFE, may determine the degree of ion transport from intestinal cells to the circulation. Gradients in pH and perhaps pCa or even pNa could allow the switching of ions between the different transporters throughout this mechanism.
23
Romig, A. D., D. R. Frear, and T. J. Headley. "High-spatial-resolution x-ray microanalysis of Al-2wt.% Cu aluminum thin films." Proceedings, annual meeting, Electron Microscopy Society of America 47 (August 6, 1989): 216–17. http://dx.doi.org/10.1017/s0424820100153051.
Анотація:
Aluminum - 2 wt.% copper alloys are commonly used in thin film form as interconnect metallization lines for integrated circuits. Experience has shown that the addition of the Cu to the Al, albeit at a decrease in conductivity, makes the metallizations more resistant to failure by electromigration. However, the mechanism by which Cu increases the resistance to electromigration has never been positively identified. One theory proposes that Cu coats the Al grain boundaries (boundaries are enriched in Cu) and retards grain boundary diffusion thereby reducing electromigration. Another theory suggests that a continuous thin layer of CuAl2 forms along the boundaries also reducing grain boundary transport and therefore the tendency to electromigrate. Recently, Frear et al. have reported on a detailed set of experiments to examine these theories from a microstructural viewpoint. Here, the details of the high spatial resolution microanalysis done to support the study of Fear, et al. are reported.Al- 2wt.% Cu was magnetron sputtered onto a borosilicate glass (BSG) coated (100) Si wafer. The Al-Cu films were sputtered at room temperature from a single source under an argon atmosphere at a deposition rate of 100 nm/min. Films 400 and 800 nm thick were prepared. The films were annealed under a 15% hydrogen forming gas (reducing) at 425°C for 35 min.
24
Bache, Kristi G., Thomas Slagsvold, Alicia Cabezas, Ken R. Rosendal, Camilla Raiborg, and Harald Stenmark. "The Growth-Regulatory Protein HCRP1/hVps37A Is a Subunit of Mammalian ESCRT-I and Mediates Receptor Down-Regulation." Molecular Biology of the Cell 15, no. 9 (September 2004): 4337–46. http://dx.doi.org/10.1091/mbc.e04-03-0250.
Анотація:
The biogenesis of multivesicular bodies and endosomal sorting of membrane cargo are driven forward by the endosomal sorting complexes required for transport, ESCRT-I, -II, and -III. ESCRT-I is characterized in yeast as a complex consisting of Vps23, Vps28, and Vps37. Whereas mammalian homologues of Vps23 and Vps28 (named Tsg101 and hVps28, respectively) have been identified and characterized, a mammalian counterpart of Vps37 has not yet been identified. Here, we show that a regulator of proliferation, hepatocellular carcinoma related protein 1 (HCRP1), interacts with Tsg101, hVps28, and their upstream regulator Hrs. The ability of HCRP1 (which we assign the alternative name hVps37A) to interact with Tsg101 is conferred by its mod(r) domain and is shared with hVps37B and hVps37C, two other mod(r) domain-containing proteins. HCRP1 cofractionates with Tsg101 and hVps28 by size exclusion chromatography and colocalizes with hVps28 on LAMP1-positive endosomes. Whereas depletion of Tsg101 by siRNA reduces cellular levels of both hVps28 and HCRP1, depletion of HCRP1 has no effect on Tsg101 or hVps28. Nevertheless, HCRP1 depletion strongly retards epidermal growth factor (EGF) receptor degradation. Together, these results indicate that HCRP1 is a subunit of mammalian ESCRT-I and that its function is essential for lysosomal sorting of EGF receptors.
25
Mercado Camargo, Jairo, Arnulfo Taron Dunoyer, and Luis A. García-Zapateiro. "The effect of storage temperature and time on total phenolics and enzymatic activity of sapodilla (Achras sapota L.)." Revista Facultad Nacional de Agronomía Medellín 69, no. 2 (July 1, 2016): 7955–63. http://dx.doi.org/10.15446/rfna.v69n2.59140.
Анотація:
The tropical fruits are sensitive to low storage temperatures, so optimal parameters have been searched for storage and transport for the purpose of maintaining its overall quality as long as possible to the consumer. The effect of different storage temperatures (6, 10, 15, 21 and 27 °C) and storage durations (0 to 20 d) on total phenolics and enzymatic activity of peroxidase (POD), catalase (CAT), and polyphenol oxidase (PPO) on sapodilla (Achras sapota L.) fruit was investigated. The extraction and quantitation of protein and phenols from fruit was performed, then the enzymatic activity of PPO, POD and CAT was determined. The concentration of total phenolics decreased in the control fruit. POD activity was 3268.7 ± 1.4 U g-1 in ripening and senescence of sapodilla stored at 27 °C. CAT activity reached a peak of 34.0 ± 0.25 U g-1 in senescence in control fruit. PPO activity remained unchanged in the ripening stage and until consumption. The best storage temperatures to prolong the post-harvest life of the sapodilla fruit were 6 °C and 10 °C when storage was at low temperatures. POD activity was inactivated during sapodilla storage at low temperatures (6 and 10 °C) and after being transferred to 27 °C the activity was reactivated. Likewise of fruits stored at 21 °C after being transferred to 27 °C the POD activity was reactive with a maximum value of 46.3 ± 0.012 U g-1. Enzyme activity decreased at low temperatures, which contributed to the preservation of the fruit, showing that the cold retards the maturation processes.
26
Strocchi, A., G. Corazza, J. Furne, C. Fine, A. Di Sario, G. Gasbarrini, and M. D. Levitt. "Measurements of the jejunal unstirred layer in normal subjects and patients with celiac disease." American Journal of Physiology-Gastrointestinal and Liver Physiology 270, no. 3 (March 1, 1996): G487—G491. http://dx.doi.org/10.1152/ajpgi.1996.270.3.g487.
Анотація:
Normal intestinal absorption of nutrients requires efficient luminal mixing to deliver solute to the brush border. Lacking such mixing, the buildup of thick unstirred layers over the mucosa markedly retards absorption of rapidly transported compounds. Using a technique based on the kinetics of maltose hydrolysis, we measured the unstirred layer thickness of the jejunum of normal subjects and patients with celiac disease, as well as that of the normal rat. The jejunum of humans and rats was perfused with varying maltose concentrations, and the apparent Michaelis constant (Km) and maximal velocity (Vmax) of maltose hydrolysis were determined from double-reciprocal plots. The true Km of intestinal maltase was determined on mucosal biopsies. Unstirred layer thickness was calculated from the in vivo Vmax and apparent Km and the in vitro Km of maltase. The average unstirred layer thickness of 11 celiac patients (170 micron) was seven times greater than that of 3 controls (25 micron). The unstirred layer of each celiac exceeded that of the controls. A variety of factors could account for the less efficient luminal stirring observed in celiacs. Although speculative, villous contractility could be an important stirring mechanism that would be absent in celiacs with villous atrophy. This speculation was supported by the finding of a relatively thick unstirred layer (mean: 106 micron) in rats, an animal that lacks villous contractility. Because any increase in unstirred layer slows transport of rapidly absorbed compounds, poor stirring appears to represent a previously unrecognized defect that could contribute to malabsorption in celiac disease and, perhaps, in other intestinal disorders.
27
Khan, Adeel, Munir Ahmad, Mukhtar Ahmed, and M. Iftikhar Hussain. "Rising Atmospheric Temperature Impact on Wheat and Thermotolerance Strategies." Plants 10, no. 1 (December 27, 2020): 43. http://dx.doi.org/10.3390/plants10010043.
Анотація:
Temperature across the globe is increasing continuously at the rate of 0.15–0.17 °C per decade since the industrial revolution. It is influencing agricultural crop productivity. Therefore, thermotolerance strategies are needed to have sustainability in crop yield under higher temperature. However, improving thermotolerance in the crop is a challenging task for crop scientists. Therefore, this review work was conducted with the aim of providing information on the wheat response in three research areas, i.e., physiology, breeding, and advances in genetics, which could assist the researchers in improving thermotolerance. The optimum temperature for wheat growth at the heading, anthesis, and grain filling duration is 16 ± 2.3 °C, 23 ± 1.75 °C, and 26 ± 1.53 °C, respectively. The high temperature adversely influences the crop phenology, growth, and development. The pre-anthesis high temperature retards the pollen viability, seed formation, and embryo development. The post-anthesis high temperature declines the starch granules accumulation, stem reserve carbohydrates, and translocation of photosynthates into grains. A high temperature above 40 °C inhibits the photosynthesis by damaging the photosystem-II, electron transport chain, and photosystem-I. Our review work highlighted that genotypes which can maintain a higher accumulation of proline, glycine betaine, expression of heat shock proteins, stay green and antioxidant enzymes activity viz., catalase, peroxidase, super oxide dismutase, and glutathione reductase can tolerate high temperature efficiently through sustaining cellular physiology. Similarly, the pre-anthesis acclimation with heat treatment, inorganic fertilizer such as nitrogen, potassium nitrate and potassium chloride, mulches with rice husk, early sowing, presoaking of a 6.6 mM solution of thiourea, foliar application of 50 ppm dithiothreitol, 10 mg per kg of silicon at heading and zinc ameliorate the crop against the high temperature. Finally, it has been suggested that modern genomics and omics techniques should be used to develop thermotolerance in wheat.
28
Kassambara, Hamidou, and Paul Kleene. "La traction animale à l’Office du Niger au Mali : du colonat au désengagement de l’Etat." Revue d’élevage et de médecine vétérinaire des pays tropicaux 57, no. 3-4 (March 1, 2004): 167. http://dx.doi.org/10.19182/remvt.9887.
Анотація:
L’Office du Niger a commencé son exploitation au début des années 1930 par la traction bovine. La grande mécanisation, introduite à partir de 1949, s’est soldée par un échec dix ans plus tard. Depuis, la traction animale est redevenue la principale source d’énergie pour le travail du sol et le transport. Jusqu’au début des années 1980, les systèmes de production étaient basés sur des techniques extensives, conduisant à des rendements moyens en paddy qui ne dépassaient que rarement 2 t/ha. A partir de 1982, une nouvelle dynamique dans les activités de l’Office du Niger s’est instaurée. La traction animale s’est fortement développée, grâce à de nouvelles facilités de crédit, du matériel mieux adapté fabriqué sur place et des services vétérinaires adéquats. Les rendements moyens en paddy sont passés à 4-6 t/ha, en fonction du type d’aménagement. La restructuration de l’Office du Niger, intervenue en 1994, a vu la suppression de la division d’élevage, les services vétérinaires étant privatisés. La fabrication et la maintenance du matériel sont désormais assurées par un réseau de forgerons. Les fonctions d’approvisionnement en matériel agricole et en boeufs de labour sont à la charge des paysans. Suite au fort endettement des organisations paysannes, les crédits matériels et boeufs ont été supprimés, ce qui rend l’accès à l’équipement difficile. Des retards dans l’exécution du calendrier agricole sont constatés dus à la mauvaise condition alimentaire et sanitaire des boeufs en début de campagne. Pour y remédier, le projet Urdoc (Unité de recherche développement observatoire de changement) a mis au point et testé un ensemble de mesures permettant d’améliorer l’état des animaux de trait. Leur diffusion se fait dans le cadre de l’approche « conseil à l’exploitation familiale ». La pérennisation de l’impact positif de la traction animale dépendra de l’engagement des différents acteurs au renforcement des services d’appui : conseil, crédit, entretien/fabrication de matériel et soins vétérinaires.
29
Lei, Yulong, Pengxiang Song, Hongpeng Zheng, Yao Fu, Xingzhong Li, and Bin Song. "Application of fuzzy logic in constant speed control of hydraulic retarder." Advances in Mechanical Engineering 9, no. 2 (February 2017): 168781401769095. http://dx.doi.org/10.1177/1687814017690956.
Анотація:
Hydraulic retarders are extensively used in commercial vehicles because of their advantages, such as their large braking torque and long continuous operating hours. In this article, the structure and working principles of hydraulic retarders are introduced, and their dynamic characteristics are analyzed. The theoretical model of a hydraulic retarder is then established based on the dynamic analysis of a vehicle driving downhill. The braking process that involves the hydraulic retarder is divided into three stages. Moreover, the filling ratio controller of the hydraulic retarder is designed by adopting fuzzy control theory to control the braking torque of the vehicle while driving downhill. The vehicle dynamic model and constant-speed control model were then established in the MATLAB/Simulink environment. The simulation results showed that the fuzzy logic controller designed in this study has good constant-torque control and anti-inference performances, which can accurately and immediately produce braking torque to satisfy the braking requirement, thereby enabling the vehicle to drive downhill at a constant speed. As a result, the control strategy designed in this article can lead to significant improvements toward a safe road transport.
30
Sankar, S., K. Parvathi, and MT Ramesan. "Structural characterization, electrical properties and gas sensing applications of polypyrrole/Cu-Al2O3 hybrid nanocomposites." High Performance Polymers 32, no. 6 (January 14, 2020): 719–28. http://dx.doi.org/10.1177/0954008319899157.
Анотація:
The present work focused on the synthesis of polypyrrole (PPy) wrapped nano copper-alumina (Cu-Al2O3) composite by an in situ polymerization of pyrrole in the presence of Cu-Al2O3 nanoparticles. The polymerized samples were systematically characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis, scanning electron microscope (SEM), high-resolution transmission electron microscope (HR-TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The properties such as AC and DC conductivity, dielectric constant, and ammonia gas sensing performance of PPy/Cu-Al2O3 composites were investigated in detail as a function of Cu-Al2O3 content. The FTIR spectra showed the existence of sharp and resolved infrared bands of nanoparticles in the PPy chain. The presence of the crystalline peaks of Cu-Al2O3 in the PPy matrix was confirmed from the XRD analysis. SEM images revealed the homogenous growth of Cu-Al2O3 in the polymer with the formation of spherically shaped particles. The HR-TEM observation showed that Cu-Al2O3 particles were dispersed at a nanometer level in the nanocomposites with a width of 30–60 nm. The glass transition temperature of composites obtained from DSC was found to be increased with increase in the content of nanoparticles. TGA analysis proved that the nano Cu-Al2O3 in the content in the composites acted as a mass transport barrier that retards the degradation of the product. The AC conductivity and dielectric constant of the nanocomposite showed that the maximum electrical properties were observed for the composite with 5 weight percentage loading of Cu-Al2O3. DC conductivity showed that the PPy/Cu-Al2O3 composites have higher electrical conductivity than PPy. The ammonia gas sensing property of the composites was significantly enhanced by the addition of Cu-Al2O3 nanoparticles. Therefore, the improved properties of synthesized PPy/Cu-Al2O3 nanocomposite can be useful for developing functional composite material for the fabrication of sensors, electronic devices, and high energy storage capacitors.
31
Zheng, Jie, Rui Xia, Najma Yaqoob, Payam Kaghazchi, Johan E. ten Elshof, and Mark Huijben. "Fast and Durable Lithium Storage Enabled By Tuning Entropy in Wadsley-Roth Phase Titanium Niobium Oxides." ECS Meeting Abstracts MA2023-02, no. 2 (December 22, 2023): 422. http://dx.doi.org/10.1149/ma2023-022422mtgabs.
Анотація:
To date, Wadsley−Roth phase materials are one of the most promising intercalation-type hosts for fast lithium transport because of the unique crystalline diffusion channels. However, the volume expansion as well as sluggish ion/electron transport kinetics retards its application in grid scale. In recent years, various strategies have been suggested to further improve the overall performance of micro-sized Wadsley-Roth phase materials, such as oxygen vacancy creation or cation substitution. Lately, entropy tuning has received considerable interest due to the favorable entropy-dominated phase-stabilization and ionic conductivity boosting effects.[1,2] However, it has only been applied in a few materials and the understanding of its function is still limited. It has been suggested that entropy-stabilized Wadsley−Roth shear phases with a more ordered structure would be stable upon electrochemical lithium (de-)insertion without a phase transition, while a more disordered structure would compromise the stability of the active material.[3] Therefore, suitable entropy tuning in entropy-stabilized Wadsley−Roth phase materials remains challenging and detailed knowledge about its effect on crystal structure and lithium storage is still lacking. Here, we have successfully realized entropy-stabilized Wadsley-Roth phase Fe0.4Ti1.6Nb10O28.8 (FTNO) in which the increased entropy, due to iron substitution, leads to a reduced grain size, and therefore, a shortened Li+ diffusion channel length.[4] Secondly, the diffusion coefficient and the reaction rate constant are enhanced leading to a reduced overpotential and an improved rate performance. Benefiting from this, the micro-sized FTNO electrode exhibits an enhanced rate ability of 73.7 mAh·g-1 at 50 C as compared to 37.9 mAh·g-1 for its TNO counterpart. Thirdly, the increased entropy results in an extended cycling durability of FTNO electrode which can deliver a specific capacity of 130.0 mAh g-1 after 6000 cycles at high rate of 10 C. Operando XRD analysis demonstrates a suppression of the a-axis deformation during the first stage of the lithiation process. The mechanism is revealed by DFT calculations and found that Fe-O bond lengths undergo less changes than Ti-O during lithiation. Finally, the potential practical application of FTNO anodes has been demonstrated by successfully constructing fast charging and stable LiFePO4‖FTNO full cells. Our results demonstrate the effectiveness of tuning entropy by iron substitution to stabilize the Wadsley-Roth phase with fast charging ability, which can be extended to other intercalation electrodes for enhanced battery applications. [1] Y. Zeng et al., Science 2022, 378, 1320-1324. [2] R. Zhang et al., Nature 2022, 610, 67-73. [3] A. A. Voskanyan et al., Chem. Mater. 2020, 32, 5301-5308 [4] J. Zheng et al., Small, smll.202301967R1, accepted.
32
Gosai, Sanjeevan, Subash Adhikari, Saugat Khanal, and Padam Bahadur Poudel. "Effects of plant growth regulators on growth, flowering, fruiting and fruit yield of cucumber (Cucumis sativus L.): A review." Archives of Agriculture and Environmental Science 5, no. 3 (September 25, 2020): 268–74. http://dx.doi.org/10.26832/24566632.2020.050306.
Анотація:
This review provides a comprehensive overview of the basic and applied aspects of different plant growth regulators in the regulation of growth and development of cucumber plants. The study is completely based on the use of secondary sources of data; related journals, government institutes, and relevant reports. Foliar application of PGRs has been shown to change the physiological and developmental processes, including plant vegetative growth, sex expression, yield, and yield components in cucumber. There are basically two types of growth regulators; plant growth promoters such as auxin, gibberellins, cytokinins, maleic hydrazide, ethephon, etc. and plant growth inhibitors such as ethylene, abscisic acids, dormins, etc. The combined use of auxins and gibberellins result in increased secondary growth. Maleic hydrazide (MH) along with Ethephon at 100 ppm each increases the number of nodes and primary branches. Ethrel at 300-400 ppm retards the secondary development and increase femaleness, and at 200-300 ppm make fruit surface smooth. Silver nitrate (AgNO3) at 400 ppm enhances the maleness in cucumber. Application of Ethephon at 300 ppm reduces the harvesting time of the fruit. Salicylic acid (at 2 doses of 0.07 mm/l + 0.18 mm/l) increases chlorophyll content and its exogenous application increases the fruit yield. Maleic Hydrazide (MH) alone at 100 ppm increases the femaleness, inhibits apical growth at 50-100 ppm, and increases fruit size at 200 ppm. Therefore, various auxin [indole-3-acetic acid (IAA), NAA], auxin transport inhibitor (TIBA), cytokinins (KIN), gibberellin [gibberellic acid (GA3)], ABA, ethylene [(2-chloroethylphosphonic acid (ethrel; ethephon; CEPA)] and growth retardant (MH) have been applied to control the vegetative growth and to maximize yield of cucumber. Numerous obstacles have hindered the quality cucumber production in Nepal; like environmental stresses, biotic and abiotic constraints, pest and disease outbreaks, and many others. The use of exogenous plant growth regulators has been crucial to Nepali cucumber producers as plant growth regulators has hasty effect on vegetative as well as the quality yield of plants. This study aims to reveal the suitable concentrations for the applications of growth regulators so that the use of such regulators is environmentally and toxicologically safe for both plants and the consumers.
33
Cvetkovic, Vladimir, and Gedeon Dagan. "Transport of kinetically sorbing solute by steady random velocity in heterogeneous porous formations." Journal of Fluid Mechanics 265 (April 25, 1994): 189–215. http://dx.doi.org/10.1017/s0022112094000807.
Анотація:
A Lagrangian framework is used for analysing reactive solute transport by a steady random velocity field, which is associated with flow through a heterogeneous porous formation. The reaction considered is kinetically controlled sorption–desorption. Transport is quantified by the expected values of spatial and temporal moments that are derived as functions of the non-reactive moments and a distribution function which characterizes sorption kinetics. Thus the results of this study generalize the previously obtained results for transport of non-reactive solutes in heterogeneous formations (Dagan 1984; Dagan et al. 1992). The results are illustrated for first-order linear sorption reactions. The general effect of sorption is to retard the solute movement. For short time, the transport process coincides with a non-reactive case, whereas for large time sorption is in equilibrium and solute is simply retarded by a factor R = 1+Kd, where Kd is the partitioning coefficient. Within these limits, the interaction between the heterogeniety and kinetics yields characteristic nonlinearities in the first three spatial moments. Asymmetry in the spatial solute distribution is a typical kinetic effect. Critical parameters that control sorptive transport asymptotically are the ratio εr between a typical reaction length and the longitudinal effective (non-reactive) dispersivity, and Kd. The asymptotic effective dispersivity for equilibrium conditions is derived as a function of parameters εr and Kd. A qualitative agreement with field data is illustrated for the zero- and first-order spatial moments.
34
Stout, T. A., C. Gibson, and M. de Ruijter Villani. "112 EFFECT OF ASYNCHRONOUS EMBRYO TRANSFER ON GLUCOSE TRANSPORTER EXPRESSION IN EQUINE TROPHECTODERM." Reproduction, Fertility and Development 27, no. 1 (2015): 148. http://dx.doi.org/10.1071/rdv27n1ab112.
Анотація:
Equine pregnancy is characterised by an unusually long pre-implantation period (40 days) during which the conceptus is entirely dependent on uterine secretions for nutrient provision; although glucose is an important nutrient during development post-blastocyst formation, little is known about its transport into the early horse conceptus. Equine embryos are also known to tolerate an unusually large degree of uterine asynchrony following embryo transfer (ET). However, negative asynchrony (recipient behind the donor) of more than 5 days markedly retards conceptus growth and development, and thereby offers a unique tool for studying the effect of the uterine environment on early development. In a preliminary study, we detected abundant mRNA expression for the facilitative glucose transporters (SLC2As) 1–3, 5, 8 and 10 and sodium-glucose co-transporter (SLC5A)11 in Day 14 to 28 equine conceptus membranes. In the current study, we evaluated the effect of uterine asynchrony on trophectodermal glucose transporter expression. Day 8 horse embryos were transferred to recipient mares that ovulated on the same day (synchronous; n = 10) or 5 days after (asynchronous; n = 10) the donor mare. The conceptuses were collected 6 or 11 days after ET (Day 14 or 19 of embryo development: n = 5 per group). Trophectodermal mRNA expression for glucose transporters was evaluated by RT-qPCR, and the effects of asynchronous ET and stage of pregnancy were analysed by two-way ANOVA followed by independent-samples t-tests. Gene expression for SLC2A3 and 8 was stable over time and treatment. Expression of SLC2A1 and SLC5A11 decreased between Days 14 and 19 in synchronous pregnancies only (P < 0.05). SLC2A2 expression increased markedly on Day 19 in synchronous (P < 0.01) but not asynchronous pregnancies (P < 0.05). SLC2A5 expression was lower in the asynchronous group on Day 14, but increased beyond expression levels in synchronous pregnancies by Day 19 (P < 0.05). In summary, expression of SLC2A1 and 3, the major placental glucose transporters, was not affected by asynchronous ET. The marked up-regulation of SLC2A2 expression between Days 14 and 19 of synchronous but not asynchronous pregnancy suggests a stage-specific function, whereas the increase in SLC2A5 at Day 19 after asynchronous ET could be a compensatory response to growth retardation. This study was funded by EpiHealthNet (Project number 317146).
35
Slanina, Petr, and Šárka Šilarová. "Moisture transport through perforated vapour retarders." Building and Environment 44, no. 8 (August 2009): 1617–26. http://dx.doi.org/10.1016/j.buildenv.2008.10.006.
36
Li, ZhiPeng, HongGuang Sun, and Renat T. Sibatov. "An investigation on continuous time random walk model for bedload transport." Fractional Calculus and Applied Analysis 22, no. 6 (December 18, 2019): 1480–501. http://dx.doi.org/10.1515/fca-2019-0077.
Анотація:
Abstract Bedload particles in the armoring layer may experience a multi-scale effect and multiple mass transfer rates between mobile and immobile domains. Anomalous transport behaviors and retarded space evolution plume cannot be described by the normal diffusion equation. In this paper, we apply the continuous time random walk model with different distributions of waiting times to capture bedload transport behavior under different conditions. Experimental data indicate that fluctuations of diffusive rates for bedload transport can be captured by the truncated power law (TPL). The retarded plume evolution can be well characterized by an exponential distribution of waiting times and advection-diffusion equation with a retarded kernel. The heavy-tailed snapshots of bedload transport are interpreted in terms of mobile and immobile states.
37
Trautmann, M. E., and C. B. Wollheim. "Characterization of glucose transport in an insulin-secreting cell line." Biochemical Journal 242, no. 3 (March 15, 1987): 625–30. http://dx.doi.org/10.1042/bj2420625.
Анотація:
The rat insulinoma-derived RINm5F cell line retains many differentiated functions of islet beta-cells. However, it fails to recognize glucose as an insulin secretagogue in the physiological concentration range. With this cell line, glucose-transport kinetics were investigated, by using a double-label technique with the non-metabolizable glucose analogue 3-O-methylglucose (OMG). RINm5F cells possess a passive glucose-transport system with high capacity and low affinity. Equilibration across the plasma membrane of extracellular OMG concentrations up to at least 20 mM is achieved within 2 min at 37 degrees C. The half-saturation of OMG uptake occurs at 32 mM. At lower temperatures OMG uptake is markedly retarded, with a temperature coefficient (Q10) of 2.9. As indicated by efflux measurements, transport is symmetrical. Cytochalasin B at micromolar concentrations and phlorrhizin in millimolar concentrations are potent inhibitors of OMG uptake. Neutralization of the secreted insulin with antibodies does not alter OMG uptake kinetics. The glucose metabolism of RINm5F cells is much exaggerated compared with that of islet beta-cells. Nonetheless, when measured in parallel to uptake, transport exceeds by far the rate of metabolism at glucose concentrations above 3 mM. Measurements of intracellular D-glucose reveal a lower intracellular glucose concentration relative to the extracellular in RINm5F cells. This seems to be due to abnormalities in the subsequent steps of glucose metabolism, rather than to abnormalities in hexose uptake. The loss of glucose-induced insulin release in RINm5F cells cannot be explained by alterations in hexose transport.
38
Gelvez García, Nancy Yaneth, and Luis Fernando Pedraza. "ENTORNOS MPLS Y ATM PARA EL TRANSPORTE DE VOZ SOBRE INTERNET." Redes de Ingeniería 3, no. 1 (August 30, 2012): 41. http://dx.doi.org/10.14483/2248762x.6406.
Анотація:
Este artículo presenta los resultados obtenidos en el estudio de la calidad de servicio sobre redes IP en tráficos sensibles al retardo como la VoIP sobre la tecnología ATM y MPLS. Se analizaran diferentes topologías con características propias que permitirán evaluar valores tales como el retardo y el ancho de banda.
39
Niño Suárez, Paola, M. Velasco Villa, and E. Aranda Bricaire. "Discretización exacta de un robot móvil con retardo de transporte." Ciencia e Ingeniería Neogranadina 16, no. 1 (January 13, 2016): 43–53. http://dx.doi.org/10.18359/rcin.1245.
Анотація:
En este trabajo se presenta la obtención del modelo exacto en tiempo discreto de un robot móvil tipo (2,0), bajo la consideración de la existencia de retardos de transporte en la señal de control, producidos por la propagación de las señales entre los sensores y actuadores del robot y el control remoto. El modelo obtenido es evaluado mediante simulación, comparando su desempeño con un modelo discreto aproximado que incluye también retardos de transporte y con el modelo en tiempo continuo del mismo sistema.
40
Budohoski, L., R. A. Challiss, A. Dubaniewicz, H. Kaciuba-Usciłko, B. Leighton, F. J. Lozeman, K. Nazar, E. A. Newsholme, and S. Porta. "Effects of prolonged elevation of plasma adrenaline concentration in vivo on insulin-sensitivity in soleus muscle of the rat." Biochemical Journal 244, no. 3 (June 15, 1987): 655–60. http://dx.doi.org/10.1042/bj2440655.
Анотація:
1. Prolonged elevation of the plasma adrenaline concentration was produced in rats by implantation of adrenaline-releasing retard-tablets. With this technique, a hyperadrenalinaemic state is maintained for at least 5 days. 2. At 6 h after implantation of the retard-tablet it was found that plasma glucose and fatty acid concentrations increased and insulin concentration decreased compared with values obtained from placebo-tablet-implanted rats. Administration of a subcutaneous glucose load demonstrated an impaired glucose tolerance in vivo, and incubation of soleus muscle strips from 6 h-hyperadrenalinaemic rats in vitro demonstrated a decreased sensitivity of the rates of glycolysis and glucose transport to insulin. 3. The sensitivities of the rates of glycolysis, glucose transport and glycogen synthesis to insulin were determined for the incubated soleus muscle preparation isolated from animals after 48 h, 72 h and 120 h duration of hyperadrenalinaemia. At 48 h after retard-tablet implantation, the sensitivity of the processes of glucose transport and glycolysis was decreased; at 72 h, the insulin-sensitivities of the rates of glycolysis and glucose transport in skeletal muscle were similar to those determined for control animals; at 120 h, however, the sensitivities of the processes of glucose transport and glycolysis were both statistically significantly increased. In contrast, no changes in the sensitivity of the process of glycogen synthesis were observed at any of the time intervals studied. 4. The possible biochemical basis for the observed changes in skeletal-muscle insulin-sensitivity with prolonged hyperadrenalinaemia is discussed.
41
Lévai, László. "The Effect of Smut Gall Tumour Infection on Iron and Zinc Uptake and Distribution in Maize Seedlings." Acta Agraria Debreceniensis, no. 15 (December 14, 2004): 27–32. http://dx.doi.org/10.34101/actaagrar/15/3353.
Анотація:
The amounts of Fe, and Zn were measured in maize seedlings infected by smut gall tumour (Ustilago maydis Dc. Cda.) and in healthy seedlings five days after infection. The amount of elements was also measured under different stress intensities. Due to the infection, as a biotic stress, the amount and distribution of examined elements have been changed. On the bases of the differences in the Fe distribution between the symptoms less and tumorial leaf parts, we have come to the conclusion that the infection also effects the mobilisation of Fe and Zn inside the plants. The Fe uptake was much higher in the infected plants and the tumour development also had an effect on the uptake and distribution of the examined elements. The experiments of infecting maize seedlings by monosporidial strain of crown gall tumour showed no tumour development. We found that the monosporidial strain also acts as a biotic stress and has an effect of iron and zinc distribution. We observed a slight difference in the iron and zinc contents in the roots of corn seedlings infected by different monosporidial sporidium concentrations, while the iron and zinc contents in the shoots were increased by the intensity of the infection. The roots do not form tumours. There is no difference between the roots of the infected and healthy corn seedlings. Since the Fe and Zn contents of the shoots of infected plants depend on the intensity of the infection, we have come to the conclusion that there must exist a „special” communication system regulating the transportation of the examined elements.In the experiments with infected maize seedlings, it became necessary to get the iron chlorosis before the disease reaches the lethal phase. Although most of the iron reserves are located in the embryo, to accelerate the chlorosis, the endosperm was removed, and it was observed, that the iron chlorosis appears later in maize seedlings when the endosperm is removed. The relative chlorophyll content of the first and second leaves was measured in iron efficient and iron deficient maize seedlings at different times.The higher IAA content of tumorial plant tissues is already known. The treatment with IAA decreases the iron concentration in the shoots and in the roots of +Fe precultured plants and increases at -Fe precultured ones. The TIBA retards the shoot-to-root transport of IAA. When the seedlings were treated simultaneously with IAA and TIBA, higher iron concentrations were observed in the shoots and in the roots of corn seedlings.We found extremely high iron concentrations in the roots of infected seedlings and, in line with this, serious damage to the roots was observed that this can be caused by the high iron content generated free radicals. The results demonstrate that IAA has a role in the shoot to root communication.
42
Emangard, Pierre-Henri, and Yves Guermond. "Les transports ferroviaires : un vieux retard à rattraper." Études Normandes 59, no. 4 (2010): 31–45. http://dx.doi.org/10.3406/etnor.2010.1824.
43
Zhao, Chongguang, Chen Li, Yilang Li, Yong Qiu, and Lian Duan. "Understanding the operational lifetime expansion methods of thermally activated delayed fluorescence sensitized OLEDs: a combined study of charge trapping and exciton dynamics." Materials Chemistry Frontiers 3, no. 6 (2019): 1181–91. http://dx.doi.org/10.1039/c9qm00185a.
Анотація:
Shallow trap assisted charge transport, fast reverse intersystem crossing of the hosts and efficient host–guest Förster resonant energy transfer in OLEDs can retard the defect formation by inhibiting exciton–polaron annhilation.
44
DERZHANSKII, Victor B., Igor A. TARATORKIN, and Alexander A. VOLKOV. "MOTION CONTROL DYNAMICS OF TRANSPORT VEHICLE ON LONG DESCENTS." Mechanics of Machines, Mechanisms and Materials 1, no. 66 (March 2024): 23–28. http://dx.doi.org/10.46864/1995-0470-2024-1-66-23-28.
Анотація:
The article provides a rationale for the need to develop an additional braking control system for a transport vehicle to limit the movement speed under the action of rolling forces and to protect the engine from exceeding the permissible speed, “overshooting” the speed. Design options for four systems that dissipate kinetic energy are considered, and the effectiveness of their use is assessed: in periodically switched off clutches in the transmission; in a hydraulic retarder, containing a rotor and a stator, where kinetic energy turns into heat and is dissipated into the environment; in two complex hydrodynamic transmissions, the design of which integrates a torque converter and a hydraulic retarder. In the first version of the system, kinetic energy turns into heat when the transmission clutches are periodically turned on and off; in the second option, energy transformation is carried out in the retarder circulation circle containing the rotor and the stator; in the third embodiment, in an additional circuit of the circulation circle of the working fluid of a hydrodynamic transmission, containing a pump, turbine, reactor wheels and an additionally introduced fourth wheel, which can serve as the stator; in the fourth version, the pump wheel of the torque converter can perform the additional function of the hydraulic retarder rotor, and the hydrodynamic transmission housing can function as the stator.
45
YI, XIZHANG, RUIQIN ZHANG, WEI FAN, and XIAOHONG ZHANG. "AN ITERATION SCHEME FOR CALCULATING TRANSPORT PROPERTIES OF MOLECULAR SYSTEMS." Journal of Theoretical and Computational Chemistry 06, no. 04 (December 2007): 975–84. http://dx.doi.org/10.1142/s0219633607003337.
Анотація:
An iteration method of functional theory is used to solve Poisson equation self-consistently in order to determine the retarded and advanced Green's function of a molecular system. The approach is demonstrated using a system with a spherical potential. The retarded and advanced Green's functions are calculated and the determined current–voltage results compare well with experimental data for the system involving Coulomb potential. The approach is expected to find wide applications in general systems.
46
de Vries, Maren, Andreas Herrmann, and Michael Veit. "A cholesterol consensus motif is required for efficient intracellular transport and raft association of a group 2 HA from influenza virus." Biochemical Journal 465, no. 2 (January 6, 2015): 305–14. http://dx.doi.org/10.1042/bj20141114.
Анотація:
The external part of the transmembrane region of HA (haemagglutinin) of influenza virus contains a cholesterol consensus motif originally identified in G-protein-coupled receptors. Various mutations in this motif retard transport of HA through the Golgi and reduce raft association.
47
Liu, Weiyi, Greg Walker, Sally Price, Xiangdong Yang, Juan Li, and Craig Bunt. "Electrospun Membranes as a Porous Barrier for Molecular Transport: Membrane Characterization and Release Assessment." Pharmaceutics 13, no. 6 (June 21, 2021): 916. http://dx.doi.org/10.3390/pharmaceutics13060916.
Анотація:
Electrospun nanofibers have been extensively studied for encapsulated drugs releasing from the inside of the fiber matrix, but have been barely looked at for their potential to control release as a semi-permeable membrane. This study investigated molecular transport behaviors across nanofiber membranes with different micro-structure sizes and compositions. Four types of membranes were made by 5% and 10% poly (ε-caprolactone) (PCL) solutions electro-spun with or without 50 nm calcium carbonate (CaCO3) nanoparticles. The membranes were tested for thickness, fiber diameter, pore size, porosity, tensile strength and elongation, contact angle of water and their impacts on molecular transport behaviors. The presence of the CaCO3 nanoparticles made the 5% membranes stronger and stiffer but the 10% membranes weaker and less stiff due to the different (covering or embedded) locations of the nanoparticles with the corresponding fibers. Solute transport studies using caffeine as the model drug found the 5% membranes further retarded release from the 10% membranes, regardless of only half the amount of material being used for synthesis. The addition of CaCO3 nanoparticles aided the water permeation process and accelerated initial transports. The difference in release profiles between 5% and 10% membranes suggests different release mechanisms, with membrane-permeability dominated release for 5% PCL membranes and solute-concentration-gradient dominated release for 10% PCL membranes.
48
Gamboa, Fausto Alexander, and Octavio José Salcedo Parra. "TRANSPORTE DE VOZ (VoIP) SOBRE REDES IPv4 e IPv6." Redes de Ingeniería 2, no. 2 (May 30, 2012): 71. http://dx.doi.org/10.14483/2248762x.7171.
Анотація:
El presente artículo tiene como finalidad evaluar el comportamiento de la VoIP en redes IPv6 y compararlo con IPv4, de igual manera presentar las arquitecturas que la soportan. Con el fin de que los resultados sean los más cercanos a la realidad, el artículo no solo se soporta en simulaciones si no en implementaciones reales. Dentro de las conclusiones más sobresalientes se encontró que la VoIP6 presenta mejor rendimiento ante el Jitter y el retardo que VoIPv4.
49
Cao, Jie, Qi Wang, Jun Mei, and Jing Xie. "Effect of 3-Aminobenzoic Acid Ethyl Ester Methanesulfonate (MS-222) on Quality of Marine Cultured Turbot (Scophthalmus maximus) during Simulated Transport in Water." Fishes 6, no. 2 (May 19, 2021): 20. http://dx.doi.org/10.3390/fishes6020020.
Анотація:
This study evaluated the effect of different concentrations (20, 40 and 60 mg/L) of 3-aminobenzoic acid ethyl ester methanesulfonate (MS-222) on the quality changes in turbot during simulated transport in water. The results showed that the ammonia nitrogen content in the transportation water of each sample increased significantly, and the dissolved oxygen level decreased. The dissolved oxygen content in MS-222-treated samples was higher than that of control group (CK) samples. For turbot flesh quality, simulated transport in water led to a decrease in moisture, fat and protein contents in all samples. The MS-222-treated turbot samples showed higher pH values, glycogen contents, springiness and chewiness values and lower lactic acid contents comparing with the CK samples during simulated transport in water. In addition, the fresh and bitter amino acids in the muscle of turbot increased in each treatment group compared to the non-transported fish at the end of the simulated transport. The results showed that MS-222 treatment could retard the turbot transport stress and improve the quality of turbot during simulated transport in water.
50
Cissé, Yacouba. "Le commissionnaire de transport, le Non Vessel Operating Common Carrier, le consortium maritime : sont-ils transporteurs maritimes ?" Revue générale de droit 34, no. 3 (November 14, 2014): 407–29. http://dx.doi.org/10.7202/1027285ar.
Анотація:
En étudiant la notion et le statut juridique du commissionnaire de transport, du Non Vessel Operating Common Carrier (NVOCC) et du consortium maritime, nous avons pu identifier ces trois acteurs du transport maritime international comme étant des transporteurs maritimes. Ainsi, bien qu’étant un intermédiaire, le commissionnaire de transport bénéficie d’un statut juridique distinct de celui du transitaire. En effet, il doit assurer le transport de la marchandise. Le Non Vessel Operating Common Carrier, acteur du shipping moderne a un statut juridique équivalent à celui du transporteur maritime en ce qu’il est aussi chargé du transport de la marchandise. Enfin, le consortium maritime, selon la nature et le degré de coopération entre ses membres, peut être identifié ou non comme transporteur maritime responsable du retard ou du dommage causé à la marchandise. Ces trois acteurs du transport maritime international ont ceci de commun qu’ils apparaissent, aux yeux des tiers non comme des intermédiaires ou des agents, mais comme de véritables transporteurs maritimes dans les pays où leurs statuts sont réglementés.