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1
Sawamura, Okamoto, and Todokoro. "Development of Mass Production Technology of Highly Permeable Nano-Porous Supports for Silica-Based Separation Membranes." Membranes 9, no. 8 (August 16, 2019): 103. http://dx.doi.org/10.3390/membranes9080103.
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Silica-based membranes show both robust properties and high-permeability, offering us great potential for applying them to harsh conditions where conventional organic membranes cannot work. Despite the increasing number of paper and patents of silica-based membranes, their industrial applications have yet to be fully realized, possibly due to their lack of technologies on scaling-up and mass production. In particular, quality of membrane supports decisively impacts final quality of silica-based separation membranes. In this study, therefore, we have developed mass producing technologies of nano-porous supports (φ 12 mm, length 400 mm) with surface center pore size distribution of 1–10 nm, which are generally used as supports for preparing separation membranes with a pore size of less than 1 nm. The developed mass production apparatuses have enabled us to reproducibly produce nano-porous silica-based supports with high permeance (e.g., N2 permeance of more than 10−5 mol m−2 s−1·Pa−1) minimizing effects of membrane defects less than 0.1% of the total flux. The developed nano-porous supports have enabled us to reproducibly produce silica-based separation membranes with high permeace and selectivity (e.g., H2 permeance of about 5 × 10−6 mol m−2 s−1 Pa−1 and H2/SF6 permeance ratio of more than 2000).
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SCHINGOETHE, D. J., D. P. CASPER, W. J. COSTELLO, and D. G. ROLLINS. "ULTRAFILTRATED WHEY PERMEATE PRODUCTS FOR GROWING-FINISHING STEERS." Canadian Journal of Animal Science 68, no. 4 (December 1, 1988): 1309–14. http://dx.doi.org/10.4141/cjas88-149.
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A 119-d field study with 50 Holstein steers weighing 408 ± 16 kg at the start evaluated feeding ultrafiltrated permeate of whey or three products made from additional processing of the permeate. Liquid permeates provided more than 17% of total dry matter intake while concentrated, ammoniated permeates provided more than 26% of crude protein intake. All whey permeate products tested were utilized well as indicated by weight gains, feed consumption, and carcass quality. Key words: Whey, whey products, cattle
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Koester, S., F. Roghmans, and M. Wessling. "Water vapor permeance: The interplay of feed and permeate activity." Journal of Membrane Science 485 (July 2015): 69–78. http://dx.doi.org/10.1016/j.memsci.2015.03.019.
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Beck, Thomas, Anja Schmidt, and Michael N. Hall. "Starvation Induces Vacuolar Targeting and Degradation of the Tryptophan Permease in Yeast." Journal of Cell Biology 146, no. 6 (September 20, 1999): 1227–38. http://dx.doi.org/10.1083/jcb.146.6.1227.
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In Saccharomyces cerevisiae, amino acid permeases are divided into two classes. One class, represented by the general amino acid permease GAP1, contains permeases regulated in response to the nitrogen source. The other class, including the high affinity tryptophan permease, TAT2, consists of the so-called constitutive permeases. We show that TAT2 is regulated at the level of protein stability. In exponentially growing cells, TAT2 is in the plasma membrane and also accumulates in internal compartments of the secretory pathway. Upon nutrient deprivation or rapamycin treatment, TAT2 is transported to and degraded in the vacuole. The ubiquitination machinery and lysine residues within the NH2-terminal 31 amino acids of TAT2 mediate ubiquitination and degradation of the permease. Starvation-induced degradation of internal TAT2 is blocked in sec18, sec23, pep12, and vps27 mutants, but not in sec4, end4, and apg1 mutants, suggesting that, upon nutrient limitation, internal TAT2 is diverted from the late secretory pathway to the vacuolar pathway. Furthermore, our results suggest that TAT2 stability and sorting are controlled by the TOR signaling pathway, and regulated inversely to that of GAP1.
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Aspiyanto, Aspiyanto, Agustine Susilowati, and Yati Maryati. "SEPARATION OF SAVORY FRACTION FROM AUTOLYSATE OF KIDNEY BEAN (Phaseolus vulgaris L.) FERMENTED BY Rhizopus sp-PL19 THROUGH CROSS-FLOW MICROFILTRATION (CFMF) MEMBRANE MODULE." Jurnal Kimia Terapan Indonesia 16, no. 1 (June 10, 2014): 39–48. http://dx.doi.org/10.14203/jkti.v16i1.7.
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Separation of savory fraction from autolysate of kidney bean (Phaseolus vulgaris L.) fermented by Rhizopus sp.-PL19 as potential seasoning agent was performed using cross-flow microfiltration (CFMF) technique in module scale. The goal of this experiment was to find out the effect of pressure and time on performance of MF membrane, and compositions of retentate and permeate. The result of experiment showed that separation and/or purification using CFMF technique gave permeate as savory fraction with better clearness and sharper aroma than retentate, but retentate had better composition than permeate. During separation increased total protein, dissolved protein and salt concentrations, but decreased total solid, reducing sugar and fat concentrations in permeate at pressure of 2 and 4 bar. Based on N-Amino concentration in permeate, the optimum condition of separation was reached at pump motor frequency of 10 Hz and room temperature with pressure of 2 and 4 bar for 10 minutes. This condition produced permeate with fluxes of 51.11 and 52.55 L/m2.hour, and concentrations of N-Amino of 5.50 and 9.80 mg/mL, dissolved protein of 1.01 and 0.97 mg/mL, total protein of 4.85 and 12.10 % (dry weight), reducing sugar of 55.75 and 53.75 mg/mL, salt of 1.16 and 1.06 %, fat of 0.41 and 0.65 %, and total solids of 7.82 and 6.35 %, respectively. Keywords : Autolysate, kidney bean (Phaseolus vulgaris L.), Rhizopus sp.-PL19, cross-flow microfiltration (CFMF), permeate, retentate. Pemisahan fraksi gurih dari autolisat kacang merah (Phaseolus vulgaris L.) terfermentasi oleh Rhizopus sp.-PL19 sebagai bahan seasoning potensial dilakukan menggunakan teknik mikrofiltrasi cross-flow (MFCF) pada modul.Penelitian bertujuan untuk mencari pengaruh tekanan dan waktu pemisahan terhadap kinerja membran mikrofiltrasi (MF) dan komposisi dalam retentat dan permeat. Hasil penelitian menunjukan bahwa pemisahan dan/atau pemurnian menggunakan teknik MFCF memberikan permeat sebagai fraksi gurih savory dengan kejernihan lebih baik dan aroma lebih tajam daripada retentat, tetapi retentat memiliki komposisi lebih baik daripada permeat. Pemisahan dengan waktu lama menaikkan konsentrasi total protein, protein terlarut dan garam, namun mengurangi konsentrasi total padatan, gula pereduksi dan lemak dalam permeat pada tekanan 2 dan 4 bar. Berdasarkan konsentrasi N-Amino dalam permeat, kondisi optimum pada pemisahan dicapai dibawah frekuensi motor pompa 10 Hz dan suhu ruang dengan tekanan 2 dan 4 bar selama 10 menit. Kondisi ini menghasilkan permeat dengan fluks masing-masing 51,11 dan 52,55 L/m2.jam serta konsentrasi N-Amino of 5,50 dan 9,80 mg/mL, protein terlarut 1,01 dan 0,97 mg/mL, total protein 4,85 dan 12,10 % (berat kering), gula pereduksi 55,75 dan 53,75 mg/mL, garam 1,16 dan 1,06 %, lemak 0,41 dan 0,65 % serta total padatan 7,82 dan 6,35 %. Kata kunci : Autolisat, kacang merah (Phaseolus vulgaris L.), Rhizopus sp.-PL19, mikrofiltrasi cross-flow (CFMF), permeat, retentat.
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Duan, Shuhong, Teruhiko Kai, and Shin-ichi Nakao. "Effect of Carbonic Anhydrase on CO2 Separation Performance of Thin Poly(amidoamine) Dendrimer/Poly(ethylene glycol) Hybrid Membranes." Membranes 9, no. 12 (December 5, 2019): 167. http://dx.doi.org/10.3390/membranes9120167.
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The effect of carbonic anhydrase (CA) on the separation performance of thin poly(amidoamine) (PAMAM) dendrimer/poly(ethylene glycol) (PEG) hybrid membranes was investigated. CA, a type of enzyme, was used to promote CO2 hydration and dehydration reactions and to assess whether these reactions were the rate-limiting step in CO2 permeation through the membrane. The relationship between the membrane thickness and the CO2 permeance was evaluated in CO2/H2 or CO2/He separation using PAMAM/PEG hybrid membranes (thickness: 10–100 μm) with and without CA. Without CA, the CO2 permeance of PAMAM/PEG hybrid membranes was not inversely proportional to the membrane thickness. On the other hand, with CA, the CO2 permeance was inversely proportional to the membrane thickness. It was implied that, without CA, the rate-limiting step of CO2 transport was either the CO2 hydration reaction at the feed side or the CO2 dehydration reaction at the permeate side. On the other hand, with CA addition, the rate-limiting step of CO2 transport was diffusion, and CO2 permeance could be increased without sacrificing the selectivity by reducing membrane thickness. The effect of the position of CA (i.e., on the surface and/or reverse surface) on CO2 separation performance was investigated to evaluate which reaction was the rate-limiting step of CO2 permeation through the membrane. It was suggested that the rate-limiting step of CO2 permeation was CO2 dehydration reaction at the permeate side.
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Tupasela, Tuomo, Heikki Koskinen, and Pirkko Antila. "Whey pretreatments before ultrafiltration." Agricultural and Food Science 3, no. 5 (September 1, 1994): 473–79. http://dx.doi.org/10.23986/afsci.72719.
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Whey is a by-product of cheesemaking. Whey dry matter contains mainly lactose, but also valuable whey proteins. The aim of this study was to develop improvements to whey protein membrane isolation processes. In our trials CaCl2 -added, pH-adjusted and heat-treated wheys were found to have MF (microfiltration) permeate fluxes about 30% higher than in untreated MF whey. The total solids and protein content of the MF permeates decreased compared to the original wheys. UF (ultrafiltration) trials were conducted using MF whey to compare it with centrifugally separated whey. The MF whey consistently maintained an UF flux about 1.5 to 2.5 times higher than that of the separated whey. Differently treated MF whey UF permeate fluxes also showed a difference. With CaCl2 addition, pH adjustment and heat treatment, the UF permeate fluxes were about 20 to 40% higher than when only MF was used. The total solids content decreased in each trial. The protein content of the UF concentrate also decreased compared to the MF permeate. The (β-lg (β-lactoglobulin) and α-la (α-lactalbumin) content was almost the same in UF concentrates as in MF permeates.
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Wong, T. Y., C. A. Murdock, S. P. Concannon, and T. D. Lockey. "Simultaneous uptake of galactose and glucose by Azotobacter vinelandii." Biochemistry and Cell Biology 69, no. 10-11 (October 1, 1991): 711–14. http://dx.doi.org/10.1139/o91-106.
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Azotobacter vinelandii growing on galactosides induced two distinct permeases for glucose and galactose. The apparent Vmax and Km of the galactose permease were 16 nmol galactose/min per 1010 cells and 0.5 mM, respectively. The apparent Vmax and Km of the glucose permease were 7.8 nmol glucose/min per 1010 cells and 0.04 mM, respectively. Excess glucose had no effect on the galactose uptake. However, excess galactose inhibited glucose transport. The galactosides-induced glucose permease also exhibited different uptake kinetics from that induced by glucose.Key words: Azotobacter, carbohydrate metabolism, melibiose, transport, galactose.
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Schreve, James L., Jennifer K. Sin, and Jinnie M. Garrett. "The Saccharomyces cerevisiae YCC5(YCL025c) Gene Encodes an Amino Acid Permease, Agp1, Which Transports Asparagine and Glutamine." Journal of Bacteriology 180, no. 9 (May 1, 1998): 2556–59. http://dx.doi.org/10.1128/jb.180.9.2556-2559.1998.
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ABSTRACT The yeast YCC5 gene encodes a putative amino acid permease and is homologous to GNP1 (encoding a high-affinity glutamine permease). Using strains with disruptions in the genes for multiple permeases, we demonstrated that Ycc5 (which we have renamed Agp1) is involved in the transport of asparagine and glutamine, performed a kinetic analysis of this activity, and showed that AGP1 expression is subject to nitrogen repression.
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Panopoulos, George, Golfo Moatsou, Chrysanthi Psychogyiopoulou, and Ekaterini Moschopoulou. "Microfiltration of Ovine and Bovine Milk: Effect on Microbial Counts and Biochemical Characteristics." Foods 9, no. 3 (March 4, 2020): 284. http://dx.doi.org/10.3390/foods9030284.
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The aim of this research work was to assess the effect of the microfiltration (ceramic membranes 1.4 μm, 50 °C) of partially defatted ovine milk (fat 0.4%) and bovine milk (fat 0.3%) characteristics. Feed milks, permeates and retentates were analyzed for microbial counts, gross composition, protein fractions, the indigenous enzymes cathepsin D and alkaline phosphatase and the behavior during renneting. It was showed that the microbial quality of both ovine and bovine permeate was improved by reduction of the total mesophilic microflora about 4 Log and 2 Log, respectively. The protein contents and the total solids contents of both permeates were significantly (p < 0.05) reduced. A further analysis of protein fractions by Reversed Phase -High Performance Liquid Chromatography (RP-HPLC) revealed lower αs1- and β-casein and higher κ-casein contents in permeates. The activity of alkaline phosphatase followed the allocation of the fat content, while activity of cathepsin D in permeates was not influenced, although somatic cells counts were removed. Regarding cheesemaking properties, the firmness of ovine curd made from the feed milk did not differ significantly from that made from the permeate. The obtained results suggested that microfiltration could be used for pre-treating of ovine milk prior to cheesemaking.
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Létoffé, Sylvie, Philippe Delepelaire, and Cécile Wandersman. "Functional Differences between Heme Permeases: Serratia marcescens HemTUV Permease Exhibits a Narrower Substrate Specificity (Restricted to Heme) Than the Escherichia coli DppABCDF Peptide-Heme Permease." Journal of Bacteriology 190, no. 6 (January 4, 2008): 1866–70. http://dx.doi.org/10.1128/jb.01636-07.
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ABSTRACT Serratia marcescens hemTUV genes encoding a potential heme permease were cloned in Escherichia coli recombinant mutant FB827 dppF::Km(pAM 238-hasR). This strain, which expresses HasR, a foreign heme outer membrane receptor, is potentially capable of using heme as an iron source. However, this process is invalidated due to a dppF::Km mutation which inactivates the Dpp heme/peptide permease responsible for heme, dipeptide, and δ-aminolevulinic (ALA) transport through the E. coli inner membrane. We show here that hemTUV genes complement the Dpp permease for heme utilization as an iron source and thus are functional in E. coli. However, hemTUV genes do not complement the Dpp permease for ALA uptake, indicating that the HemTUV permease does not transport ALA. Peptides do not inhibit heme uptake in vivo, indicating that, unlike Dpp permease, HemTUV permease does not transport peptides. HemT, the periplasmic binding protein, binds heme. Heme binding is saturable and not inhibited by peptides that inhibit heme uptake by the Dpp system. Thus, the S. marcescens HemTUV permease and, most likely, HemTUV orthologs present in many gram-negative pathogens form a class of heme-specific permeases different from the Dpp peptide/heme permease characterized in E. coli.
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Garty, H., T. J. Furlong, D. E. Ellis, and K. R. Spring. "Sorbitol permease: an apical membrane transporter in cultured renal papillary epithelial cells." American Journal of Physiology-Renal Physiology 260, no. 5 (May 1, 1991): F650—F656. http://dx.doi.org/10.1152/ajprenal.1991.260.5.f650.
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The efflux of sorbitol from the rabbit papillary epithelial cell line PAP-HT25 occurs through a specific transport pathway, which we denote the "sorbitol permease." The permease was studied by measuring cell volume changes that accompanied osmotic swelling and by determination of the sorbitol efflux from plasma membrane vesicles. The cell volume studies showed that sorbitol efflux in response to hypotonicity occurred only across the apical membrane of the cells and that loss of sorbitol was the primary mechanism for regulatory volume decrease (RVD) by these cells. Quinidine, a permeant inhibitor of the sorbitol permease, was shown to prevent RVD when added to either apical or basolateral bathing solution. Cell volume experiments also showed that the permease was present only on the apical membrane of cells that had been grown in isotonic medium and did not accumulate sorbitol. The permease could be demonstrated in membrane vesicles obtained from cells exposed to a hypotonic environment before being homogenized. Quinidine blocked the sorbitol efflux from vesicles indicating that it either directly inhibited the permease or a membrane-associated activation step.
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Wollmuth, L. P., and B. Hille. "Ionic selectivity of Ih channels of rod photoreceptors in tiger salamanders." Journal of General Physiology 100, no. 5 (November 1, 1992): 749–65. http://dx.doi.org/10.1085/jgp.100.5.749.
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Ionic selectivity of Ih channels of tiger salamander rod photoreceptors was investigated using whole-cell voltage clamp. Measured reversal potentials and the Goldman-Hodgkin-Katz voltage equation were used to calculate permeability ratios with 20 mM K+ as a reference. In the absence of external K+, Ih is small and hard to discern. Hence, we defined Ih as the current blocked by 2 mM external Cs+. Some small amines permeate Ih channels, with the following permeability ratios (PX/PK):NH4+, 0.17; methylammonium, 0.06; and hydrazine, 0.04. Other amines are tially impermeant: dimethylammonium (< 0.02), ethylammonium (< 0.01), and tetramethylammonium (< 0.01). When K+ is the only external permeant ion and its concentration is varied, the reversal potential of Ih follows the Nernst potential for a K+ electrode. Ih channels are also permeable to other alkali metal cations (PX/PK): T1+, > 1.55; K+, 1; Rb+, > 0.55; Na+, 0.33; Li+, 0.02. Except for Na+, the relative slope conductance had a similar sequence (GX/GK): T1+, 1.07; K+, 1; Rb+, 0.37; NH4+, 0.07; Na+, 0.02. Based on permeabilities to organic cations, the narrowest part of the pore has a diameter between 4.0 and 4.6 A. Some permeant cations have large effects on the gating kinetics of Ih channels; however, permeant cations appear to have little effect on the steady-state activation curve of Ih channels. Lowering K+ or replacing K+ with Na+ reduces the maximal conductance of Ih but does not shift or change the steepness of its voltage dependence. With ammonium or methylammonium replacing K+ a similar pattern is seen, except that there is a small positive shift of approximately 10 mV in the voltage dependence.
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Dehkordi, Javad Aminian, Seyed Saeid Hosseini, Prodip K. Kundu, and Nicolas R. Tan. "Mathematical Modeling of Natural Gas Separation Using Hollow Fiber Membrane Modules by Application of Finite Element Method through Statistical Analysis." Chemical Product and Process Modeling 11, no. 1 (March 1, 2016): 11–15. http://dx.doi.org/10.1515/cppm-2015-0052.
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Abstract Hollow fiber membrane permeators used in the separation industry are proven as preferred modules representing various benefits and advantages to gas separation processes. In the present study, a mathematical model is proposed to predict the separation performance of natural gas using hollow fiber membrane modules. The model is used to perform sensitivity analysis to distinguish which process parameters influence the most and are necessary to be assessed appropriately. In this model, SRK equation was used to justify the nonideal behavior of gas mixtures and Joule-Thomson equation was employed to take into account the changes in the temperature due to permeation. Also, the changes in temperature along shell side was calculated via thermodynamic principles. In the proposed mathematical model, the temperature dependence of membrane permeance is justified by the Arrhenius-type equation. Furthermore, a surface mole fraction parameter is introduced to consider the effect of accumulation of less permeable component adjacent to the membrane surface in the feed side. The model is validated using experimental data. Central Composite Designs are used to gain response surface model. For this, fiber inner diameter, active fiber length, module diameter and number of fibers in the module are taken as the input variables related to the physical geometries. Results show that the number as well as the length of the fibers have the most influence on the membrane performance. The maximum mole fraction of CO2 in the permeate stream is observed for low number of fibers and fibers having smaller active lengths. Also results indicate that at constant active fiber length, increasing the number of fibers decreases the permeate mole fraction of CO2. The findings demonstrate the importance of considering appropriate physical geometries for designing hollow fiber membrane permeators for practical gas separation applications.
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Marchal, Christelle, Rosine Haguenauer-Tsapis, and Daniele Urban-Grimal. "A PEST-Like Sequence Mediates Phosphorylation and Efficient Ubiquitination of Yeast Uracil Permease." Molecular and Cellular Biology 18, no. 1 (January 1, 1998): 314–21. http://dx.doi.org/10.1128/mcb.18.1.314.
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ABSTRACT Uptake of uracil by the yeast Saccharomyces cerevisiaeis mediated by a specific permease encoded by the FUR4gene. Uracil permease located at the cell surface is subject to two covalent modifications: phosphorylation and ubiquitination. The ubiquitination step is necessary prior to permease endocytosis and subsequent vacuolar degradation. Here, we demonstrate that a PEST-like sequence located within the cytoplasmic N terminus of the protein is essential for uracil permease turnover. Internalization of the transporter was reduced when some of the serines within the region were converted to alanines and severely impaired when all five serines within the region were mutated or when this region was absent. The phosphorylation and degree of ubiquitination of variant permeases were inversely correlated with the number of serines replaced by alanines. A serine-free version of this sequence was very poorly phosphorylated, and elimination of this sequence prevented ubiquitination. Thus, it appears that the serine residues in the PEST-like sequence are required for phosphorylation and ubiquitination of uracil permease. A PEST-like sequence in which the serines were replaced by glutamic acids allowed efficient permease turnover, suggesting that the PEST serines are phosphoacceptors.
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Kuehn, M. J., R. Schekman, and P. O. Ljungdahl. "Amino acid permeases require COPII components and the ER resident membrane protein Shr3p for packaging into transport vesicles in vitro." Journal of Cell Biology 135, no. 3 (November 1, 1996): 585–95. http://dx.doi.org/10.1083/jcb.135.3.585.
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In S. cerevisiae lacking SHR3, amino acid permeases specifically accumulate in membranes of the endoplasmic reticulum (ER) and fail to be transported to the plasma membrane. We examined the requirements of transport of the permeases from the ER to the Golgi in vitro. Addition of soluble COPII components (Sec23/24p, Sec13/31p, and Sar1p) to yeast membrane preparations generated vesicles containing the general amino acid permease. Gap1p, and the histidine permease, Hip1p. Shr3p was required for the packaging of Gap1p and Hip1p but was not itself incorporated into transport vesicles. In contrast, the packaging of the plasma membrane ATPase, Pma1p, and the soluble yeast pheromone precursor, glycosylated pro alpha factor, was independent of Shr3p. In addition, we show that integral membrane and soluble cargo colocalize in transport vesicles, indicating that different types of cargo are not segregated at an early step in secretion. Our data suggest that specific ancillary proteins in the ER membrane recruit subsets of integral membrane protein cargo into COPII transport vesicles.
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Belitsky, Boris R. "Role of Branched-Chain Amino Acid Transport in Bacillus subtilis CodY Activity." Journal of Bacteriology 197, no. 8 (February 2, 2015): 1330–38. http://dx.doi.org/10.1128/jb.02563-14.
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ABSTRACTCodY is a branched-chain amino acid-responsive transcriptional regulator that controls the expression of several dozen transcription units inBacillus subtilis. The presence of isoleucine, valine, and leucine in the growth medium is essential for achieving high activity of CodY and for efficient regulation of the target genes. We identified three permeases—BcaP, BraB, and BrnQ—that are responsible for the bulk of isoleucine and valine uptake and are also involved in leucine uptake. At least one more permease is capable of efficient leucine uptake, as well as low-affinity transport of isoleucine and valine. The lack of the first three permeases strongly reduced activity of CodY in an amino acid-containing growth medium. BcaP appears to be the most efficient isoleucine and valine permease responsible for their utilization as nitrogen sources. The previously described strong CodY-mediated repression of BcaP provides a mechanism for fine-tuning CodY activity by reducing the availability of amino acids and for delaying the utilization of isoleucine and valine as nitrogen and carbon sources under conditions of nutrient excess.IMPORTANCEBacillus subtilisCodY is a global transcriptional regulator that is activated by branched-chain amino acids (BCAA). Since the level of BCAA achieved by intracellular synthesis is insufficient to fully activate CodY, transport of BCAA from the environment is critical for CodY activation, but the permeases needed for such activation have not been previously identified. This study identifies three such permeases, reports their amino acid transport specificity, and reveals their impact on CodY activation.
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Roberg, Kevin J., Stephen Bickel, Neil Rowley, and Chris A. Kaiser. "Control of Amino Acid Permease Sorting in the Late Secretory Pathway of Saccharomyces cerevisiae by SEC13, LST4, LST7 and LST78." Genetics 147, no. 4 (December 1, 1997): 1569–84. http://dx.doi.org/10.1093/genetics/147.4.1569.
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Abstract The SEC13 gene was originally identified by temperature-sensitive mutations that block all protein transport from the ER to the Golgi. We have found that at a permissive temperature for growth, the sec13-1 mutation selectively blocks transport of the nitrogen-regulated amino acid permease, Gaplp, from the Golgi to the plasma membrane, but does not affect the activity of constitutive permeases such as Hip1p, Can1p, or Lyp1p. Different alleles of SEC13 exhibit different relative effects on protein transport from the ER to the Golgi, or on Gap1p activity, indicating distinct requirements for SEC13 function at two different steps in the secretory pathway. Three new genes, LST4, LST7, and LSTB, were identified that are also required for amino acid permease transport from the Golgi to the cell surface. Mutations in LST4 and LST7 reduce the activity of the nitrogen-regulated permeases Gap1p and Put4p, whereas mutations in LST8 impair the activities of a broader set of amino acid permeases. The LST8 gene encodes a protein composed of WD-repeats and has a close human homologue. The LST7 gene encodes a novel protein. Together, these data indicate that SEC13, LST4, LST7, and LST8 function in the regulated delivery of Gap1p to the cell surface, perhaps as components of a post-Golgi secretory-vesicle coat.
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Baker, R. W. "Separation of Volatile Organic Compounds from Water by Pervaporation." MRS Bulletin 24, no. 3 (March 1999): 50–53. http://dx.doi.org/10.1557/s0883769400051927.
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Pervaporation is a membrane process used to separate liquid mixtures. Separation is achieved by a combination of evaporation and membrane permeation. As a result, the process offers the possibility of removing dissolved volatile organic compounds (VOCs) from water, dehydrating organic solvents, and separating mixtures of components with close boiling points or azeotropes that are difficult to separate by distillation or other means.A schematic diagram of the pervaporation process is shown in Figure 1. In the example shown, the feed liquid is a solution of toluene in water which contacts one side of a membrane that is selectively permeable to toluene. The permeate, enriched in toluene, is removed as a vapor from the other side of the membrane. The driving force for the process is the difference in the partial vapor pressures of each component in the feed liquid and the permeate gas. This driving force can be increased by raising the temperature of the feed liquid to increase its vapor pressure or by decreasing the permeate gas pressure. The permeate gas pressure can be adjusted by using a vacuum pump, but industrially the most economical method is to cool and condense the vapor. Condensation spontaneously generates a vacuum. The permeate vapor pressure is then determined by the temperature of the permeate condenser and the composition of the permeate liquid generated by cooling and condensing the permeate vapor.Pervaporation membranes are made by coating a thin layer of selective polymer material onto a microporous support.
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Dehesa-Carrasco, U., J. J. Ramírez-Luna, C. Calderón-Mólgora, R. S. Villalobos-Hernández, and J. J. Flores-Prieto. "Experimental evaluation of a low pressure desalination system (NF-PV), without battery support, for application in sustainable agriculture in rural areas." Water Supply 17, no. 2 (September 27, 2016): 579–87. http://dx.doi.org/10.2166/ws.2016.147.
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Desalination driven by solar energy represents an appealing solution for agricultural irrigation in remote areas. In this work, a desalination system based on a photovoltaic-powered nanofiltration (NF-PV) membrane is studied. The experimental work explored the effect of the influent concentration and solar radiation on permeate production, energy consumption, recovery rate and quality of the permeate product. Four cases of different inlet conditions of influent concentrations were studied. In each set, the influent concentration was kept constant, varying only the irradiance along the solar day. In addition, a unit cost of permeated water was estimated. The maximum tested energy consumption was 1.55 Kwh m−3, with a concentration of 2,539 mg L−1 of total dissolved solids. The NF-PV system produces 2.16 to 4.8 m3 d−1, with a permeate water unit cost of 1.05–0.47 US$ m−3.
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Nanda, Abdul Rakhim, Amrullah Mansida, Anita Anita, and Yayu Sulistiawati. "PENGARUH KRIB BAMBU TIPE PERMEABEL TERHADAP GERUSAN TEBING DI BELOKAN SUNGAI (STUDI EKSPERIMENTAL)." TEKNIK HIDRO 12, no. 2 (August 21, 2019): 1–10. http://dx.doi.org/10.26618/th.v12i2.2805.
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Kerusakan Daerah Aliran Sungai (DAS) menyebabkan Gerusan tebing sungai menambah sedimentasi di dasar sungai.Penelitian ini bertujuan untuk mengetahui pengaruh karakteristik aliran di daerah krib bambu tipe permeable dan pengaruh pemasangan jarak krib bambu tipe permeable terhadap gerusan tebing di belokan sungai. Jenis penelitian yang digunakan adalah eksperimen laboratorium. Pengaruh pemasangan krib tipe permeabel terhadap karakteristik aliran dan tanpa pemasangan krib menyebabkan terjadinya perubahan karakteristik aliran di beberapa titik dari super kritis ke sub kritis dan pemasangan jarak krib bambu tipe permeabel terhadap gerusan tebing di belokan sungai berpengaruh pada volume gerusan, dimana semakin kecil jarak pemasangan krib yang digunakan maka akan semakin kecil volume gerusan yang terjadi. Hal ini diakibatkan karena krib mengalami agradasi dan degradasi di daerah krib dengan jarak yang cenderung lebih besar
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Inami, Hisao, Chie Abe, and Yasuhisa Hasegawa. "Development of Ammonia Selectively Permeable Zeolite Membrane for Sensor in Sewer System." Membranes 11, no. 5 (May 10, 2021): 348. http://dx.doi.org/10.3390/membranes11050348.
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Ammonia (NH3) and hydrogen sulfide (H2S) are hazardous and odorous gases. A special device that is not affected by other gases is necessary so that it can detect such gases. Zeolite membranes can separate the desired component selectively by molecular sieving and selective adsorption. LTA-, MFI-, and FAU-type zeolite membranes were prepared in this study, and the permeation and separation performances were determined for the ternary mixture of NH3, H2S, and N2 to develop an NH3 selectively permeable membrane. Although the separation factors of NH3 were high enough for the LTA-type zeolite membrane, the NH3 permeance was the lowest among the three membranes. In contrast, the FAU-type zeolite membrane with Si/Al = 1.35 showed a high enough NH3 permeance and a NH3/N2 separation factor. The membrane modification and varying the membrane composition were carried out to reduce the H2S permeance. As a result, the H2S permeance could be decreased by modification with silane coupling agents, and a separation factor of NH3 toward H2S of over 3000 was achieved.
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Urban-Grimal, D., B. Pinson, J. Chevallier, and R. Haguenauer-Tsapis. "Replacement of Lys by Glu in a transmembrane segment strongly impairs the function of the uracil permease from Saccharomyces cerevisiae." Biochemical Journal 308, no. 3 (June 15, 1995): 847–51. http://dx.doi.org/10.1042/bj3080847.
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The co-transport of uracil and protons through the plasma membrane of the yeast Saccharomyces cerevisiae is mediated by a specific permease encoded by the FUR4 gene. The uracil permease is a multi-spanning membrane protein that follows the secretory pathway to the plasma membrane. Recent experimental data led to the proposal of a two-dimensional model of its topology. A spontaneous mutant corresponding to the substitution of Lys-272 by glutamic acid was obtained. The influence of this mutation was studied by comparing the wild-type and mutant permeases produced in a strain carrying a chromosomal deletion of the FUR4 gene. The mutant permease is correctly targeted to the plasma membrane and its stability is similar to that of the wild-type permease. The uptake parameters for the mutant permease were impaired and showed an approximately 65-fold increase of apparent K(m) and a decrease in apparent Vmax. Equilibrium binding measurements with enriched plasma membrane preparations showed an approximately 70-fold increase in apparent Kd in the mutant, whereas its Bmax. was similar to that of the wild type. Lys-272 is fully conserved in the uracil permease family and is predicted to lie in the fourth transmembrane segment of the protein. It seems to be essential for both efficient uracil binding and translocation.
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Ferro-Luzzi Ames, G. "Energy coupling in periplasmic permeases: The histidine permease as a model system." Research in Microbiology 141, no. 3 (January 1990): 341–48. http://dx.doi.org/10.1016/0923-2508(90)90009-f.
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Yau Seng Mah, Darrien, Siew Ling Loh, Md Abdul Mannan, and Wan Hashim Wan Ibrahim. "Modelling of Surface Permeation in Multiple-Orifice Permeable Road." International Journal of Engineering & Technology 7, no. 3.18 (August 2, 2018): 40. http://dx.doi.org/10.14419/ijet.v7i3.18.16670.
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A patent-pending StormPav green pavement is introduced here as a form of permeable road, in which the system employed precast concrete pieces as modular units. The pavement layer consists of hexagonal plates with each a service inlet to drain water. This study is exploring the water draining capability or technically surface permeation of these service inlets. Virtual and physical modelling are performed to investigate the service inlets as multiple orifices to permeate surface water of the said permeable road. Both modelling efforts have deduced that the permeable road has 18,000 – 24,000 mm/hr of permeation rate when subjected to a 5-minute red-alert storm (>60mm/hr of intensity). It implies that StormPav green pavement has superior surface permeation against the forming of water ponding and flash flood on roads.
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Dean, A. M. "A molecular investigation of genotype by environment interactions." Genetics 139, no. 1 (January 1, 1995): 19–33. http://dx.doi.org/10.1093/genetics/139.1.19.
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Abstract The fitnesses conferred by seven lactose operons, which had been transduced into a common genetic background from natural isolates of Escherichia coli, were determined during competition for growth rate-limiting quantities of galactosyl-glycerol, a naturally occurring galactoside. The fitnesses of these same operons have been previously determined on lactose and three artificial galactosides, lactulose, methyl-galactoside and galactosyl-arabinose. Analysis suggests that although marked genotype by environment interactions occur, changes in the fitness rankings are rare. The relative activities of the beta-galactosidases and the permeases were determined on galactosyl-glycerol, lactose, lactulose and methyl-galactoside. Both enzymes display considerable kinetic variation. The beta-galactosidase alleles provide no evidence for genotype by environment interactions at the level of enzyme activity. The permease alleles display genotype by environment interactions with a few causing changes in activity rankings. The contributions to fitness made by the permeases and the beta-galactosidases were partitioned using metabolic control analysis. Most of the genotype by environment interaction at the level of fitness is generated by changes in the distribution of control among steps in the pathway, particularly at the permease where large control coefficients ensure that its kinetic variation has marked fitness effects. Indeed, changes in activity rankings at the permease account for the few changes in fitness rankings. In contrast, the control coefficients of the beta-galactosidase are sufficiently small that its kinetic variation is in, or close to, the neutral limit. The selection coefficients are larger on the artificial galactosides because the control coefficients of the permease and beta-galactosidase are larger. The flux summation theorem requires that control coefficients associated with other steps in the pathway must be reduced, implying that the selection at these steps will be less intense on the artificial galactosides. This suggests that selection intensities need not be greater in novel environments.
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Tkachuk, B., V. Lisovyi, M. Kolesnyk, E. Sokol, R. Tomashevskyi, N. Kotulevych, and L. Mykhailiuk. "Optimal design and ensuring the stable functioning the pretreatment systems and obtaining high-quality permeate for HD/HDF." Ukrainian Journal of Nephrology and Dialysis, no. 1(65) (January 14, 2020): 58–64. http://dx.doi.org/10.31450/ukrjnd.1(65).2020.08.
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Since 2011, at the Department of Industrial and Biomedical Electronics, NTU "KHPI" together with KNPE of KRC "RMCCUN n. a. V. I. Shapoval” with the participation of State Institute “Institute of Nephrology of the National Academy of Medical Sciences of Ukraine” is carrying out research aimed at improving patient safety the hemodialysis (HD)or hemodiafiltration (HDF) procedure. Especially prepared water ensures the safety and quality of the HD or HDF procedure. For the carrying-out, one HD session is necessary more than 150 liters of permeate. Poor quality permeates causes various complications, even can lead to fatal consequences. Therefore a constantly guaranteed qualitative permeate is an important component of safe HD or HDF.
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Tazaki, Asahi, Shintaro Takeuchi, Suguru Miyauchi, Lucy T. Zhang, Ryo Onishi, and Takeo Kajishima. "Fluid Permeation Through A Membrane With Infinitesimal Permeability Under Reynolds Lubrication." Journal of Mechanics 36, no. 5 (August 14, 2020): 637–48. http://dx.doi.org/10.1017/jmech.2020.38.
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ABSTRACTTo understand the lubrication-dominated permeation through a membrane, numerical simulations of permeation through a moving corrugated permeable membrane is carried out with a fully validated numerical method. Through comparisons between the numerical results and the results of an asymptotic analysis of permeate flux (under an infinitesimal permeability condition) using Reynolds lubrication equation, the effect of permeation on lubrication and its inverse effect (i.e., the dependence of permeation on lubrication) are discussed. The linear and non-linear dependences of the relaxation of the lubrication pressure due to membrane permeation are identified. The effect of the tangential component of the permeate flux is evaluated by a linear analysis, and the limitation of Reynolds-type lubrication is discussed.
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Fang, Yu. "Analysis on Permeability of High Permeability Layer-Penetration Oil Influencing Factors." Applied Mechanics and Materials 580-583 (July 2014): 2524–27. http://dx.doi.org/10.4028/www.scientific.net/amm.580-583.2524.
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This article from the permeability condition, half-rigid base type, material requirements, penetrating agent and emulsifier choice, permeation resistance, etc., through the analysis of the factors affecting the permeability of permeable layer of emulsified asphalt, and guided by the factors above, we developed and prepared a new high permeability permeate layer emulsification asphalt, the tests showed that it has good permeability.
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Seres, Zita, Ljubica Dokic, Biljana Pajin, Dragana Soronja-Simovic, Drago Subaric, Jurislav Babic, and Aleksandar Fistes. "Influence of the operating parameters on the flux during microfiltration of the steepwater in the starch industry." Acta Periodica Technologica, no. 43 (2012): 225–35. http://dx.doi.org/10.2298/apt1243225s.
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The subject of the work is the possibility of applying microfiltration through a ceramic tubular membrane with 100 nm pore sizes to the steepwater obtained in the production process of corn starch. The dry matter content should be reduced in the steepwater permeate. Thus the consumption of the process water would be reduced, the nutrients from the steepwater could be exploited as feed and the wastewater problem would consequently be solved. The objective of the work was to examine the influence of the operating parameters on the permeate flux during steepwater microfiltration. The parameters that vary in the course of microfiltration, were the transmembrane pressur and flow rate, while the permeate flux and dry matter content of the permeate and retentate were the dependent parameters, constantly monitored during the process. Another objective of this study was to investigate the influence of static turbulence promoter on the permeate flux during steepwater microfiltration. Static mixers enhance permeate flux, thus the microfiltration can be performed longer. As a result of the statistical analysis, the optimal conditions for steepwater microfiltration were determined. The maximum value of the permeate flux without mixer (25 lm-2h-1) was achieved at a pressure of 2 bars and a flow rate around 100 lh-1. With the use of static mixer the flux is 2,5 times higher compared to the one obtained without the mixer. The dry matter content of the permeat after 2.5 hours of mucrofiltration was lowered by 40%.
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Halim, M. H. M., F. Kadirkhan, W. N. F. W. Mustapa, W. K. Soh, and S. Y. Yeo. "Natural gas sweetening polymeric membrane: Established optimum operating condition at 70% of CO2 concentration feed gas stream." Malaysian Journal of Fundamental and Applied Sciences 16, no. 1 (February 2, 2020): 54–58. http://dx.doi.org/10.11113/mjfas.v16n1.1471.
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PETRONAS embarks on breakthrough technology for natural gas sweetening in high CO2 gas fields. Membrane technology is found to be one with high potential and a promising technology for bulk CO2 removal from natural gas. It can be suited to wide operating conditions to process varied natural gas composition, pressure and temperature. This paper focuses on the extensive development of PETRONAS in-house membrane and its evaluation for gas separation performance for high CO2 feed gas at different operating conditions; eg. feed gas flowrate, temperature, pressure, CO2 concentration in mixed gas system, and permeate pressure. For all the cases in this study, samples were tested at optimum gas flowrate of 1000 standard cm3/min (sccm) to obtain representative membrane performance. Feed gas pressure and CO2 concentration have shown significantly affect membrane permeation properties; whereas feed gas temperature and permeate pressure showed negligible impact. There is a trade-off between permeance and selectivity when CO2 concentration is increased from 40% to 70%; where the CO2 permeance increased by 12% which consequently reduces CO2/CH4 selectivity by 15%. In summary, the membrane developed in this study demonstrates high pressure durability up to 50 bar and temperature up to 55oC with satisfactory gas separation performance in the presence of high CO2 concentration in feed gas (up to 70% CO2). This work is breakthrough in establishing the operational boundary of PETRONAS Membrane for technology development and deployment in monetizing high CO2 gas field.
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Smart, M. G., J. R. Aist, and H. W. Israel. "Some exploratory experiments on the permeability of papillae induced in barley coleoptiles by Erysiphe graminis f.sp. hordei." Canadian Journal of Botany 65, no. 4 (April 1, 1987): 745–49. http://dx.doi.org/10.1139/b87-099.
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Impermeability to ions and small molecules has been cited as a possible basis of the resistance of papillae to fungal penetration: nonporous papillae could prevent nutrient transfer or disrupt recognition between pathogen and suscept. We have tested the ability of lanthanum ions and a few, selected, small molecules to permeate both normal papillae and oversize papillae induced in barley coleoptiles by Erysiphe graminis f.sp. hordei. The probes were applied to living, usually untreated, coleoptiles and were detected by light or electron microscopy. Hydrophilic probes up to 389 Da were able to permeate both kinds of papillae freely. Although the results with the lipophilic probes were more difficult to interpret, the 479-Da probe did not freely permeate unaltered papillae of either kind. We conclude that unaltered papillae are permeable to some cations and small, hydrophilic molecules and infer that impermeability to similar chemicals cannot explain why oversize papillae, but not normal papillae, are highly resistant to penetration by the fungus.
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Varlakhanova, Natalia V., Bryan A. Tornabene, and Marijn G. J. Ford. "Feedback regulation of TORC1 by its downstream effectors Npr1 and Par32." Molecular Biology of the Cell 29, no. 22 (November 2018): 2751–65. http://dx.doi.org/10.1091/mbc.e18-03-0158.
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TORC1 (target of rapamycin complex) integrates complex nutrient signals to generate and fine-tune a growth and metabolic response. Npr1 (nitrogen permease reactivator) is a downstream effector kinase of TORC1 that regulates the stability, activity, and trafficking of various nutrient permeases including the ammonium permeases Mep1, Mep2, and Mep3 and the general amino acid permease Gap1. Npr1 exerts its regulatory effects on Mep1 and Mep3 via Par32 (phosphorylated after rapamycin). Activation of Npr1 leads to phosphorylation of Par32, resulting in changes in its subcellular localization and function. Here we demonstrate that Par32 is a positive regulator of TORC1 activity. Loss of Par32 renders cells unable to recover from exposure to rapamycin and reverses the resistance to rapamycin of Δ npr1 cells. The sensitivity to rapamycin of cells lacking Par32 is dependent on Mep1 and Mep3 and the presence of ammonium, linking ammonium metabolism to TORC1 activity. Par32 function requires its conserved repeated glycine-rich motifs to be intact but, surprisingly, does not require its localization to the plasma membrane. In all, this work elucidates a novel mechanism by which Npr1 and Par32 exert regulatory feedback on TORC1.
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Mänttäri, M., and M. Nyström. "Membrane filtration for tertiary treatment of biologically treated effluents from the pulp and paper industry." Water Science and Technology 55, no. 6 (March 1, 2007): 99–107. http://dx.doi.org/10.2166/wst.2007.217.
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Discharge waters from activated sludge processes in the pulp and paper industry and from a municipal wastewater treatment plant were filtered with various nanofiltration (NF) and low pressure reverse osmosis (RO) membranes. The purpose was to study flux, retention, and permeate quality after membrane filtration by using a high shear (CR-250/2) filter. The suitability of the achieved permeates for reuse at the industrial site is also discussed. The NF permeate was practically free from colour and organic compounds but contained significant amount of inorganic compounds e.g. chloride ions, especially when a high amount of sulphate containing discharge waters were filtered, in which case a low pressure RO membrane was needed to successfully remove monovalent anions. Organic compounds were almost completely retained by NF and RO membranes and organic carbon in the permeate was less than 10 mg/dm3 on average. The achieved permeate can easily be reused in paper production. Nanofiltration has a significantly higher flux and also a lower fouling tendency than reverse osmosis but it passes through monovalent ions when there is a high sulphate concentration in the water. Therefore, RO might be needed in such cases to produce excellent process water.
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Voets, Thomas, Annelies Janssens, Jean Prenen, Guy Droogmans, and Bernd Nilius. "Mg2+-dependent Gating and Strong Inward Rectification of the Cation Channel TRPV6." Journal of General Physiology 121, no. 3 (February 24, 2003): 245–60. http://dx.doi.org/10.1085/jgp.20028752.
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TRPV6 (CaT1/ECaC2), a highly Ca2+-selective member of the TRP superfamily of cation channels, becomes permeable to monovalent cations in the absence of extracellular divalent cations. The monovalent currents display characteristic voltage-dependent gating and almost absolute inward rectification. Here, we show that these two features are dependent on the voltage-dependent block/unblock of the channel by intracellular Mg2+. Mg2+ blocks the channel by binding to a site within the transmembrane electrical field where it interacts with permeant cations. The block is relieved at positive potentials, indicating that under these conditions Mg2+ is able to permeate the selectivity filter of the channel. Although sizeable outward monovalent currents were recorded in the absence of intracellular Mg2+, outward conductance is still ∼10 times lower than inward conductance under symmetric, divalent-free ionic conditions. This Mg2+-independent rectification was preserved in inside-out patches and not altered by high intracellular concentrations of spermine, indicating that TRPV6 displays intrinsic rectification. Neutralization of a single aspartate residue within the putative pore loop abolished the Mg2+ sensitivity of the channel, yielding voltage-independent, moderately inwardly rectifying monovalent currents in the presence of intracellular Mg2+. The effects of intracellular Mg2+ on TRPV6 are partially reminiscent of the gating mechanism of inwardly rectifying K+ channels and may represent a novel regulatory mechanism for TRPV6 function in vivo.
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Kajama, Mohammed Nasir, Yilmaz Yildirim, Usman Habu Taura, Alhaji Shehu Grema, and Shehu Abdulrahman. "Silica Modified Membrane for Carbon Dioxide Separation from Natural Gas." Nano Hybrids and Composites 21 (June 2018): 43–52. http://dx.doi.org/10.4028/www.scientific.net/nhc.21.43.
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A dip-coating technique was applied to prepare a selective membrane on a commercial ceramic mesoporous support. Single gas components used for permeance and selectivity were CH4, CO2, H2, He, N2, and O2(BOC UK) with at least 99.999 (% v/v) purity. The permeances and selectivities were obtained at room temperature and transmembrane pressure differences between 0.05 up to 5.0 barg. Gas permeation experiments showed the permeance of CO2to be strongly influenced by surface diffusion mechanism. Single gas experiment showed linear flow dependence on the inverse square root of molecular weight at room temperature and 1.0 barg. The single gas selectivities were found to be higher than the ideal Knudsen separation mechanism. The highest CO2/CH4selectivity value of 24.07 was obtained at 0.7 barg and room temperature.
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Bertram, Ralph, Maximilian Schlicht, Kerstin Mahr, Harald Nothaft, Milton H. Saier, and Fritz Titgemeyer. "In Silico and Transcriptional Analysis of Carbohydrate Uptake Systems of Streptomyces coelicolor A3(2)." Journal of Bacteriology 186, no. 5 (March 1, 2004): 1362–73. http://dx.doi.org/10.1128/jb.186.5.1362-1373.2004.
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ABSTRACT Streptomyces coelicolor is the prototype for the investigation of antibiotic-producing and differentiating actinomycetes. As soil bacteria, streptomycetes can metabolize a wide variety of carbon sources and are hence vested with various specific permeases. Their activity and regulation substantially determine the nutritional state of the cell and, therefore, influence morphogenesis and antibiotic production. We have surveyed the genome of S. coelicolor A3(2) to provide a thorough description of the carbohydrate uptake systems. Among 81 ATP-binding cassette (ABC) permeases that are present in the genome, we found 45 to encode a putative solute binding protein, an essential feature for carbohydrate permease function. Similarity analysis allowed the prediction of putative ABC systems for transport of cellobiose and cellotriose, α-glucosides, lactose, maltose, maltodextrins, ribose, sugar alcohols, xylose, and β-xylosides. A novel putative bifunctional protein composed of a substrate binding and a membrane-spanning moiety is likely to account for ribose or ribonucleoside uptake. Glucose may be incorporated by a proton-driven symporter of the major facilitator superfamily while a putative sodium-dependent permease of the solute-sodium symporter family may mediate uptake of galactose and a facilitator protein of the major intrinsic protein family may internalize glycerol. Of the predicted gene clusters, reverse transcriptase PCRs showed active gene expression in 8 of 11 systems. Together with the previously surveyed permeases of the phosphotransferase system that accounts for the uptake of fructose and N-acetylglucosamine, the genome of S. coelicolor encodes at least 53 potential carbohydrate uptake systems.
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Bachem, Steffi, and Jörg Stülke. "Regulation of the Bacillus subtilis GlcT Antiterminator Protein by Components of the Phosphotransferase System." Journal of Bacteriology 180, no. 20 (October 15, 1998): 5319–26. http://dx.doi.org/10.1128/jb.180.20.5319-5326.1998.
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ABSTRACT Bacillus subtilis utilizes glucose as the preferred source of carbon and energy. The sugar is transported into the cell by a specific permease of the phosphoenolpyruvate:sugar phosphotransferase system (PTS) encoded by the ptsGHI operon. Expression of this operon is induced by glucose and requires the action of a positive transcription factor, the GlcT antiterminator protein. Glucose availability is sensed by glucose-specific enzyme II (EIIGlc), the product of ptsG. In the absence of inducer, the glucose permease negatively controls the activity of the antiterminator. The GlcT antiterminator has a modular structure. The isolated N-terminal part contains the RNA-binding protein and acts as a constitutively acting antiterminator. GlcT contains two PTS regulation domains (PRDs) at the C terminus. One (PRD-I) is the target of negative control exerted by EIIGlc. A conserved His residue (His-104 in GlcT) is involved in inactivation of GlcT in the absence of glucose. It was previously proposed that PRD-containing transcriptional antiterminators are phosphorylated and concomitantly inactivated in the absence of the substrate by their corresponding PTS permeases. The results obtained with B. subtilis glucose permease with site-specific mutations suggest, however, that the permease might modulate the phosphorylation reaction without being the phosphate donor.
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Odey, Emmanuel A., Kaijun Wang, Zifu Li, Abdulmoseen S. Giwa, and Bodjui O. Abo. "Feasibility of wastewater resource recovery using pilot-scale membrane reactor with long-term operation." Energy & Environment 30, no. 4 (October 3, 2018): 662–71. http://dx.doi.org/10.1177/0958305x18802782.
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With the growing interest in resource recovery from wastewater, research has been put forward to realize this aim using different approaches. Here, we considered several conditions necessary for the experiment, with the primary goal of recovering concentrates suitable for biogas recovery and water reuse through the pilot-scale membrane reactor (PSMR). The new concept enables the feasibility of recovering permeates and concentrates directly from the PSMR. From the results obtained, permeate chemical oxygen demand was within 20 mg/L to 38 mg/L; the total nitrogen yielded an average value of 22.14 ± 3.53 mg/L; ammonia yielded an average value of 13.34 ± 1.18 mg/L; and the total phosphorus presented a value of 0.46 ± 0.32 mg/L. Permeates recovered from the experiment feature potential use for agriculture, groundwater, and lake recharge, as the chemical oxygen demand, total nitrogen, total phosphorus, and ammonia contents are low and acceptable for these purposes. Concentrates from two days of solid retention time ranged from 6050 mg/L to 10,000 mg/L, which was suitable for anaerobic digestion for biogas recovery. A further experiment is suggested to enable the removal of more ammonia, total phosphorus, and total nitrogen in permeate to enable its use for a domestic purpose.
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Palmer, Laura K., Darren Wolfe, Jessica L. Keeley, and Ralph L. Keil. "Volatile Anesthetics Affect Nutrient Availability in Yeast." Genetics 161, no. 2 (June 1, 2002): 563–74. http://dx.doi.org/10.1093/genetics/161.2.563.
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Abstract Volatile anesthetics affect all cells and tissues tested, but their mechanisms and sites of action remain unknown. To gain insight into the cellular activities of anesthetics, we have isolated genes that, when overexpressed, render Saccharomyces cerevisiae resistant to the volatile anesthetic isoflurane. One of these genes, WAK3/TAT1, encodes a permease that transports amino acids including leucine and tryptophan, for which our wild-type strain is auxotrophic. This suggests that availability of amino acids may play a key role in anesthetic response. Multiple lines of evidence support this proposal: (i) Deletion or overexpression of permeases that transport leucine and/or tryptophan alters anesthetic response; (ii) prototrophic strains are anesthetic resistant; (iii) altered concentrations of leucine and tryptophan in the medium affect anesthetic response; and (iv) uptake of leucine and tryptophan is inhibited during anesthetic exposure. Not all amino acids are critical for this response since we find that overexpression of the lysine permease does not affect anesthetic sensitivity. These findings are consistent with models in which anesthetics have a physiologically important effect on availability of specific amino acids by altering function of their permeases. In addition, we show that there is a relationship between nutrient availability and ubiquitin metabolism in this response.
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Zhang, Qi, Hua Wang, Xinfei Fan, Shuo Chen, Hongtao Yu, and Xie Quan. "A controlled wet-spinning and dip-coating process for preparation of high-permeable TiO2 hollow fiber membranes." Water Science and Technology 73, no. 4 (October 26, 2015): 725–33. http://dx.doi.org/10.2166/wst.2015.543.
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In order to improve the permeate flux of photocatalytic membranes, we present an approach for coupling TiO2 with ceramic hollow fiber membranes. The ceramic hollow fiber membranes with high permeate flux were fabricated by a controlled wet-spinning process using polyethersulfone (PESf) and ceramic powder as precursors and 1-methyl-2-pyrrolidinone as solvent, and the subsequent TiO2 coating was performed by a dip-coating process using tetra-n-butyl titanate as precursor. It has been found that the PESf/ceramic powder ratio could influence the structure of the membranes. Here the as-prepared TiO2 hollow fiber membranes had a pure water flux of 4,450 L/(m2·h). The performance of the TiO2 hollow fiber membrane was evaluated using humic acid (HA) as a test substance. The results demonstrated that this membrane exhibited a higher permeate flux under UV irradiation than in the dark and the HA removal efficiency was enhanced. The approach described here provides an operable route to the development of high-permeable photocatalytic membranes for water treatment.
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Salanenka, Yuliya A., and Alan G. Taylor. "Seedcoat Permeability: Uptake and Post-germination Transport of Applied Model Tracer Compounds." HortScience 46, no. 4 (April 2011): 622–26. http://dx.doi.org/10.21273/hortsci.46.4.622.
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The seedcoat permeability, uptake, and transport of model fluorescent tracers were investigated in snapbean (Phaseolus vulgaris), pepper (Capsicum annuum), tomato (Solanum lycopersicum), onion (Allium cepa), cucumber (Cucumis sativus), and lettuce (Lactuca sativa) seeds. Nine fluorescent tracers and one vital stain were selected to represent a diversity of physicochemical properties (lipophilicity, electrical charge, etc.) and to simulate behavior of applied seed treatments. To study seedcoat permeability, tracers were applied to seeds as dry powders, and treated seeds were sown in moistened sand at 20 °C and removed after 18 to 24 h, a time before visible germination. Imbibed seeds were dissected and fluorescence (staining) was observed in embryos with a dissecting microscope under ultraviolet (365 nm) or visible radiation. Seedcoat permeability of species to solutes was grouped into three categories: 1) permeable—snapbeans; 2) selectively permeable—tomato, pepper, and onion; and 3) non-permeable—cucumber and lettuce. Systemic tracers that failed to permeate seedcoats during seed imbibition were taken up by roots or hypocotyls after visible germination.
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Utto, Weerawate, Rittirong Pruthtikul, Patcharee Malila, Athapol Noomhorm, and John E. Bronlund. "Concentration and Temperature Dependences of Effective Ethanol Vapor Permeance of Plastic Films Utilized in Controlled Release-Based Active Packaging for Horticultural Products." Key Engineering Materials 718 (November 2016): 45–48. http://dx.doi.org/10.4028/www.scientific.net/kem.718.45.
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In the present work effective film permeances to ethanol vapor (FPE) of Low Density Polyethylene (LDPE) and Nylon/PE films were determined in relations to ethanol vapor concentrations and storage temperatures (10°C and 25°C). The FPE was characterized using the isostatic and the gravimetric methods. The values of FPE show dependences on both storage temperatures and ethanol vapor concentration (0.25-3.17 mol⋅m-3). Experimental data on FPE were well predicted with the exponential growth model with Root Mean Square Error (RMSE) value in a range of 0.0002-0.005. At comparable ethanol vapor concentration, research findings show that (i) average permeances of LDPE were higher than those of Nylon/PE, and, (2) the effective permeances measured at 10°C, for each films, were higher than those measured at 25°C, except the permeance of LDPE film measured at 10°C using 0.6-0.7 mol⋅m-3 was lower than that measured at 25°C.
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Solomon, Jonathan, Laura Su, Stanley Shyn, and Alan D. Grossman. "Isolation and Characterization of Mutants of the Bacillus subtilis Oligopeptide Permease with Altered Specificity of Oligopeptide Transport." Journal of Bacteriology 185, no. 21 (November 1, 2003): 6425–33. http://dx.doi.org/10.1128/jb.185.21.6425-6433.2003.
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ABSTRACT Bacterial oligopeptide permeases are members of the large family of ATP binding cassette transporters and typically import peptides of 3 to 5 amino acids, apparently independently of sequence. Oligopeptide permeases are needed for bacteria to utilize peptides as nutrient sources and are sometimes involved in signal transduction pathways. The Bacillus subtilis oligopeptide permease stimulates competence development and the initiation of sporulation, at least in part, by importing specific signaling peptides. We isolated rare, partly functional mutations in B. subtilis opp. The mutants were resistant to a toxic tripeptide but still retained the ability to sporulate and/or become competent. The mutations, mostly in the oligopeptide binding protein located on the cell surface, affected residues whose alteration appears to change the specificity of oligopeptide transport.
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Pasantes-Morales, H., R. Sanchez Olea, D. Miranda, and J. Moran. "Volume regulation in NIH/3T3 cells not expressing P-glycoprotein. I. Regulatory volume decrease." American Journal of Physiology-Cell Physiology 272, no. 6 (June 1, 1997): C1798—C1803. http://dx.doi.org/10.1152/ajpcell.1997.272.6.c1798.
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Exposure of NIH/3T3 fibroblasts not expressing P-glycoprotein to 50, 30, 20, and 10% hyposmotic solutions led to cell volume increases of 70, 32, 21, and 12%, respectively. After swelling, NIH/3T3 cells exhibited regulatory volume decrease (RVD), attaining complete volume recovery after 30 min except in 50% hyposmotic solution, in which volume recovery was 76%. RVD was accelerated by gramicidin and inhibited by the Cl channel blockers 5-nitro-2-(3-phenylpropylamino)-benzoic acid, 1,9-dideoxyforskolin, dipyridamole, and niflumic acid and by the K channel, blocker quinidine. RVD was reduced 15% by removal of extracellular Ca. The pathway opened by hypotonicity was highly permeable to K and Rb and only partly permeable to other cations. Most anions were able to permeate, with a permeability ranking of nitrate > benzoate = iodide > thiocyanate > chloride > > gluconate. The pathway was permeable to neutral amino acids, with a permeability ranking of glycine > alanine > glutamate > taurine > gamma-aminobutyric acid > glutamine. The pathway was not permeable to basic amino acids. These results show that, despite the absence of P-glycoprotein, NIH/3T3 cells exhibit RVD with properties similar to those expressed in most cell types.
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Venezuela, A. L., R. F. Cantão, R. S. Ongaratto, and R. N. Haneda. "MODIFIED SERIES RESISTANCE MODEL - DETERMINATION OF MEAN CONCENTRATION BY INTEGRAL TRANSFORMATION." Revista de Engenharia Térmica 17, no. 1 (June 30, 2018): 94. http://dx.doi.org/10.5380/reterm.v17i1.62266.
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There are several mathematical models that describe permeate flow in membrane separation processes. Among these, the series resistance model plays a prominent role. It takes into account membrane strength, concentration polarization, polarized layer and fouling to describe the permeate flow over time. In this work, an analysis of the modified series resistance model was performed, in which the resistance by polarization of the concentration is defined as being directly proportional to the transmembrane pressure. The proportionality constant is given by the product of a specific coefficient of resistance – which is determined by means of experimental data – the thickness of the boundary layer of concentration and the mean concentration. Due to the inability to obtain experimentally the value of the average concentration within the boundary layer of concentration, its simulation is carried out from the conservation equation of the chemical species. Thus, the objective of the present work was to solve the equation of the conservation of chemical species using GITT (Generalized Integral Transform Technique) and apply the modified series resistance model to describe the permeate flow of a solution of dextran through a permeable tube under laminar flow. GITT provided satisfactory results for the mean concentration, verified by comparison with the permeate flow obtained by the series resistance model with experimental results reported in the literature.
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Jin, Fan, Meng, Zhang, Meng, Yang, and Liu. "Theoretical and Experimental Insights into the Mechanism for Gas Separation through Nanochannels in 2D Laminar MXene Membranes." Processes 7, no. 10 (October 15, 2019): 751. http://dx.doi.org/10.3390/pr7100751.
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Clarifying the mechanism for the gas transportation in the emerging 2D materials-based membranes plays an important role on the design and performance optimization. In this work, the corresponding studies were conducted experimentally and theoretically. To this end, we measured the gas permeances of hydrogen and nitrogen from their mixture through the supported MXene lamellar membrane. Knudsen diffusion and molecular sieving through straight and tortuous nanochannels were proposed to elucidate the gas transport mechanism. The average pore diameter of 5.05 Å in straight nanochannels was calculated by linear regression in the Knudsen diffusion model. The activation energy for H2 transport in molecular sieving model was calculated to be 20.54 kJ mol−1. From the model, we can predict that the gas permeance of hydrogen (with smaller kinetic diameter) is contributed from both Knudsen diffusion and molecular sieving mechanism, but the permeance of larger molecular gases like nitrogen is sourced from Knudsen diffusion. The effects of the critical conditions such as temperature, the diffusion pore diameter of structural defects, and the thickness of the prepared MXene lamellar membrane on hydrogen and nitrogen permeance were also investigated to understand the hydrogen permeation difference from Knudsen diffusion and molecular sieving. At room temperature, the total hydrogen permeance was contributed 18% by Knudsen diffusion and 82% by molecular sieving. The modeling results indicate that molecular sieving plays a dominant role in controlling gas selectivity.
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Day, Rachel E., Peter J. Rogers, Ian W. Dawes, and Vincent J. Higgins. "Molecular Analysis of Maltotriose Transport and Utilization by Saccharomycescerevisiae." Applied and Environmental Microbiology 68, no. 11 (November 2002): 5326–35. http://dx.doi.org/10.1128/aem.68.11.5326-5335.2002.
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ABSTRACT Efficient fermentation of maltotriose is a desired property of Saccharomyces cerevisiae for brewing. In a standard wort, maltotriose is the second most abundant sugar, and slower uptake leads to residual maltotriose in the finished product. The limiting factor of sugar metabolism is its transport, and there are conflicting reports on whether a specific maltotriose permease exists or whether the mechanisms responsible for maltose uptake also carry out maltotriose transport. In this study, radiolabeled maltotriose was used to show that overexpression of the maltose permease gene, MAL61, in an industrial yeast strain resulted in an increase in the rate of transport of maltotriose as well as maltose. A strain derived from W303-1A and lacking any maltose or maltotriose transporter but carrying a functional maltose transport activator (MAL63) was developed. By complementing this strain with permeases encoded by MAL31, MAL61, and AGT1, it was possible to measure their specific transport kinetics by using maltotriose and maltose. All three permeases were capable of high-affinity transport of maltotriose and of allowing growth of the strain on the sugar. Maltotriose utilization from the permease encoded by AGT1 was regulated by the same genetic mechanisms as those involving the maltose transcriptional activator. Competition studies carried out with two industrial strains, one not containing any homologue of AGT1, showed that maltose uptake and maltotriose uptake were competitive and that maltose was the preferred substrate. These results indicate that the presence of residual maltotriose in beer is not due to a genetic or physiological inability of yeast cells to utilize the sugar but rather to the lower affinity for maltotriose uptake in conjunction with deteriorating conditions present at the later stages of fermentation. Here we identify molecular mechanisms regulating the uptake of maltotriose and determine the role of each of the transporter genes in the cells.
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ECKNER, KARL F., and EDMUND A. ZOTTOLA. "Potential for the Low-Temperature Pasteurization of Dairy Fluids Using Membrane Processing." Journal of Food Protection 54, no. 10 (October 1, 1991): 793–97. http://dx.doi.org/10.4315/0362-028x-54.10.793.
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Raw milk, reconstituted skim milk, skim milk, sweet whey, and acid whey were membrane processed on different units from several manufacturers using various membranes with pore sizes ranging from nanofiltration through microfiltration. The bulk fluids were inoculated with either Staphylococcus aureus 196E, Salmonella typhimurium var. Hillfarm, and/or Pseudomonas fragi 4973. In addition, indigenous microorganisms were present. The permeate and retentate streams were monitored for bacterial numbers. Percent total solids of the permeate streams was determined. Temperatures and pressures were controlled. In no cases were the bacteria completely retained while concomitantly allowing permeated solids to equal the solids in the original bulk fluid. Findings indicated different membranes of same molecular weight cut-off exhibited dissimilar bacterial retention characteristics. Unit design/configuration appeared to play a role in retention of bacteria. Spiral wound microfiltration and ultrafiltration membranes reduced bacterial loads in the permeate by 98.9 to 99.99% while allowing 5 to 6% of the solids in the bulk fluid to pass through the membrane. The bulk fluid does not appear to affect the bacterial retention. The different wheys, milks, and reconstituted skim milk showed similar reductions in bacterial numbers when microfiltered or ultrafiltered through the same type of membrane. All three test microbes demonstrated similar declines during membrane processing. It appeared that bacterial morphology and size did not affect the bacterial retention characteristics. Results indicated that low-temperature membrane processing will not eliminate all microorganisms in the permeate nor did all milk components pass through the membrane into the permeate.
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Jiwad, Foad Srhan, Mojtaba Behnam Taghadosi, and Ahmed Abed Al-Kadhem Majhool. "Development of the Hydro Static Wind Turbine Powered RO System for Maximum Power Point and Maximum Permeate Flow Tracking." Al-Qadisiyah Journal for Engineering Sciences 13, no. 1 (May 10, 2020): 60–66. http://dx.doi.org/10.30772/qjes.v13i1.649.
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Wind energy is one of the cheapest sources of energy that may solve the Climate change problem and fresh water scarcity challenges. This article introduces a novel Desalination Wind Turbine that is cheaper and more efficient than the common wind turbine, especially offshore wind turbines. In this system, the wind energy transmitted to the water pump by a hydraulic transmission line. The RO module is used for fresh water production. The pressure recovery module is added to RO system, to increase the permeated flow. It can be increased the permeate flow up to 45%, which is significant. The Maximum Power Point Tracking (MPPT) based on the hydraulic oil pressure measurement is implemented. In addition, the Maximum Permeate Flow Tracking control loop, similar to MPPT, is introduced to optimized the pressure of the RO system. It is increased the annual permeate production up to 8%. The long term performance of the system, such as annual water production is calculated and the ability of the system to MPPT and the wind turbulence and gust is analyzed. The rotor speed overshoot of the closed loop system is less than 16%, which is acceptable.