Journal articles on the topic 'PVC membrane ISE'
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1
Wahab, Abd Wahid. "THE EFFECT OF PVC-BASED MEMBRANE COMPOSITION AND Zn(II), Cd(II) AND Pb(II) INTERFERING IONS TO Hg(II) ION SELECTIVE ELECTRODE (ISE) PERFORMANCE BY USING DBA218C6 IONOPHORE." Indonesian Journal of Chemistry 6, no. 1 (June 13, 2010): 27–31. http://dx.doi.org/10.22146/ijc.21768.
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The effect of PVC (Polyvinylchloride)-Based Membrane Composition to Ion Selective Electrode (ISE)-Hg(II) Performance using Ionophore DBA218C6 (N,N'-Dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclo octadecane), Plasticizer NPOE (Nitrophenyl Octhyl Ether), Anionic Site KTCPB (Potassium Tetrakis (4-chloro phenyl) borate) have been performed. Membrane compositions used were:(a) PVC (30 mg), NPOE (60 mg), DBA218C6(6 mg) and KTCPB (4 mg); (b) PVC(30 mg), NPOE (60 mg), DBA218C6(7 mg) and KTCPB (3 mg); (c) PVC (30 mg), NPOE (59 mg), DBA218C6 (8 mg) and KTCPB( 3 mg). The concentration range of interference ions Zn(II), Cd(II) and Pb(II) were 1.0 x 10-3 - 1.0 x 10-1 M. ISE-Hg(II) performance for membrane composition of 30 : 60 : 6 : 4 was 26.34 mV per decade (Nernstian Slope value) on Hg(II) concentration range of 1.0x10-6 - 1.0 x 10-1 M , membrane composition of 30 : 60 : 7 : 3 was 27.71 mV per decade on Hg(II) concentration range of 1.0 x10-6 - 1.0 x10-1 M, and membrane composition of 30 : 59 : 8 : 3 was 28.52 mV per decade on Hg(II) concentration range of 1.0 x10-6 - 1.0 x10-1 M with activity between pH 1.0-3.0. The concentration of interference ions : Zn(II), Cd(II) and Pb(II) in the range of 1.0 x 10-3 - 1.0 x 10-1 M with the ratio of the primary ion to interference ions of 4 : 1 gave real effect. As results, selectivities and sensitivities between ISE-Hg(II) and Ionophore DBA218C6 could be determined by PVC-Based Membrane Composition and the effect of Zn(II), Cd(II) and Pb(II) interference ions was observed in the concentration of 1,0 x10-3 - 1,0 x10-1 M. Keywords: membrane composition effect, ionophore DBA218C6, ISE-Hg(II)
2
Thomas, J. D. R. "Devices for ion-sensing and pX measurements." Pure and Applied Chemistry 73, no. 1 (January 1, 2001): 31–38. http://dx.doi.org/10.1351/pac200173010031.
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Thirty years of ion-selective electrode (ISE) researches at the University of Wales, Cardiff are outlined. They summarize developments of PVC membrane ISEs, first for calcium and then of other systems, including the improved calcium dioctyl-phenyl-phosphate sensor for calcium and those of ion-exchangers, polyalkoxylates, and cyclic and acyclic polyethers for various anions and cations. Electrodes based on polyalkoxylates have interesting properties toward the polyethers themselves. Some ISE failure causes are discussed. Attention is given to applications, including analysis of wash liquors and nonionic surfactants, biomedical roles, and studies of sulfate-reducing bacteria activity. Coated-wire ISEs and ion-selective field effect transistors (ISFETs) are mentioned, as are other modes of ISE deployment. The review concludes with some fundamental features of PVC electrode membranes as determined by radiotracer, applied potential, and potentiostatic approaches.
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Muhali, Muhali. "APLIKASI SENYAWA AMIDA HUMAT SEBAGAI IONOFOR DALAM MEMBRAN ELEKTRODA SELEKTIF ION Ni (II)." Prisma Sains : Jurnal Pengkajian Ilmu dan Pembelajaran Matematika dan IPA IKIP Mataram 1, no. 1 (June 30, 2013): 67. http://dx.doi.org/10.33394/j-ps.v1i1.520.
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The amide compound derived from humic acid has been applied as ionophore in ion selective electrode (ISE) measurement based on poly vinyl chloride (PVC) membrane. The carboxylic acid group of the humic acid was first modified to the corresponding amide and is expected to form complex with the target cation. This work aims at obtaining selectivity coefficient towards Ni2+ ion. The products of the reactions were observed using infra red (IR) spectrometer. The amide compound derived from humic acid was immobilized into the membrane with composition percentage (w/w) as the following 32% of PVC, 64% of plasticizer of either [orto-nitrophenil octyl ether (NPOE) or dioctylpthalate (DOP) or dibenzyl ether (DBE)], 2% of lipophilic anion [sodiumtetraphenylborate (NaTPB), and oleic acid], and 2% of ionophore the humic amide, respectively. The results show that ISE membrane give selective response to the Ni2+ ion at pH of 4,5 with response time of approximately 80 seconds. Among many others, the cations that give strong emf interference include Cu2+,Li+, K+, Pb2+, Na+, Zn2+, and Ca2+. The Nernstian factor of ISE membrane is close to +28 mV per decade with linear range of concentration of pNi2+ of 1-6, with composition PVC membrane, DBE as plasticizer, oleic acid as lipophilic anion, and humic amide as ionophore, respectively.
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Sukru Kalayci, Sukru Kalayci. "High Sensitivity Sulphite Membrane Selective Electrode and its Application." Journal of the chemical society of pakistan 43, no. 4 (2021): 451. http://dx.doi.org/10.52568/000590/jcsp/43.04.2021.
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In this study, the new sulphite sensitive ion-selective electrode (ISE) was prepared. The ISE was prepared from a combination of 5% perfluorooctanesulfonic acid (PFOS), 40% PVC and 55% dibutylphthalate (DBF).The sensitivity of the ISE to 1.0x10- 7-1.0x10-1 M sulphite concentration was 58 and#177; 4 mV. Electrode sensitivity was characterized. The response time of this electrode is short and 30 s. The lifetime of ISE was approximately 210 days when used five times a day. It was determined that it can work at any pH value. It is not sensitive to anions and cations that may be present in the determination medium. The detection limit of the electrode against the sulfide concentration was measured as 1.2x10-8 M. The amount of sulfites in dried apricots in Turkey, was measured with electrodes. Sulfite amount in dried apricot was determined as 2.328 and#177; 0.2417 mg / kg according to the average of 5 experiments and 95% confidence interval. The same sample was measured with DPP as 2.521 and#177; 0.2785.The validation of the obtained results in each case was proved by statistical “t” and “F” tests.
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Sukru Kalayci, Sukru Kalayci. "High Sensitivity Sulphite Membrane Selective Electrode and its Application." Journal of the chemical society of pakistan 43, no. 4 (2021): 451. http://dx.doi.org/10.52568/000590.
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In this study, the new sulphite sensitive ion-selective electrode (ISE) was prepared. The ISE was prepared from a combination of 5% perfluorooctanesulfonic acid (PFOS), 40% PVC and 55% dibutylphthalate (DBF).The sensitivity of the ISE to 1.0x10- 7-1.0x10-1 M sulphite concentration was 58 and#177; 4 mV. Electrode sensitivity was characterized. The response time of this electrode is short and 30 s. The lifetime of ISE was approximately 210 days when used five times a day. It was determined that it can work at any pH value. It is not sensitive to anions and cations that may be present in the determination medium. The detection limit of the electrode against the sulfide concentration was measured as 1.2x10-8 M. The amount of sulfites in dried apricots in Turkey, was measured with electrodes. Sulfite amount in dried apricot was determined as 2.328 and#177; 0.2417 mg / kg according to the average of 5 experiments and 95% confidence interval. The same sample was measured with DPP as 2.521 and#177; 0.2785.The validation of the obtained results in each case was proved by statistical “t” and “F” tests.
6
Umaningrum, Dewi, Radna Nurmasari, Siti Hasnah, Maria Dewi Astuti, Kiki Amalia Wardhani, and Shofia Qalby. "The Coated-Wire Ion-Selective Electrode (CWISE) of Tartrazine Using Chitosan as an Ionophore." Jurnal Kimia Sains dan Aplikasi 24, no. 6 (August 25, 2021): 206–12. http://dx.doi.org/10.14710/jksa.24.6.206-212.
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Research on the Ion-Selective Electrode (ISE) of coated wire-type tartrazine using chitosan as an ionophore has been developed. The variables used in the manufacture of ISE are membrane composition and immersion time. Meanwhile, the basic characteristics of ISE measured are Nernst value, measurement concentration range, detection limit, and measurement response time. The results showed that ISE tartrazine coated wire type had an optimum membrane composition in a mixture of chitosan: PVC: DOP of 3: 34: 63 (% w/w) and a membrane immersion time 20 minutes. The basic characteristics of ISE produce a Nernst value of 20.976 mV/decade. The measurement concentration range is 1×10-7-1×10-2 M with a detection limit of 2.749×10-7 M or 0.1469 ppm. The response time ranges from 10-60 seconds, with an average of 40 seconds.
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Morakchi, K., A. Zazoua, A. Hamel, Saida Zougar, R. Kherrat, and Nicole Jaffrezic-Renault. "Functionalization of ISE Sensor for Metal Ion Detection." Materials Science Forum 609 (January 2009): 249–54. http://dx.doi.org/10.4028/www.scientific.net/msf.609.249.
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In this work, we report the study of functionalized platinum (Pt) electrodes based on a polymeric membrane (PVC) including an ionophore (ethyln diamin tetracetic EDTA) sensitive for mercury ions Hg2+. The optimised working conditions of the sensors have been studied with regard to the sensitivity performances; in particular, the polarisation was adjusted to - 0.2V/SCE. Ion sensitivity of sensors have been tested for Hg(II) via Cd(II) in aqueous solution. A layer of EDTA deposited on platinum electrode has been characterised by impedance spectroscopy and cyclic voltammetry methods.
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Dali, Nasriadi, Seniwati Dali, Armadi Chairunnas, Hilda Ayu Melvi Amalia, and Sri Ayu Andini Puspitasari. "Highly Selective and Sensitive Determination of Hg(II) Ions Using Ion Selective Electrodes (ISE) Coated with the BEC4ND1 Ionophore as Membranes." JKPK (Jurnal Kimia dan Pendidikan Kimia) 7, no. 2 (August 31, 2022): 242. http://dx.doi.org/10.20961/jkpk.v7i2.62213.
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<p>The research on the highly selective and sensitive determination of Hg(II) ions using ion-selective electrodes (ISE) coated with the BEC4ND1 ionophore as a membrane has been successfully carried out. ISE was designed using the membrane composition of the [(BEC4ND1 ionophore : PTCPB : DOS : PVC) (3 : 2 : 60 : 35 % w/w)]. The ESI-BEC4ND1 ionophore has good characteristics where it shows a sensitivity value of 29.933 mV/decade in the Hg(II) ion concentration range of 10<sup>-9</sup> - 10<sup>-1</sup> M with a limit of detection (LoD) of 10<sup>-7</sup> M. The response time obtained is in the range of 4 - 8 minutes with a relative standard deviation (RSD) of 0.548. The ESI-BEC4ND1 ionophore also shows the average value of selectivity coefficient (K<sub>ij</sub>) < 1. These results indicate that the presence of Zn(II), Cd(II), and Pb(II) ions as interfering ions in the analyte solution does not affect the performance of the ESI-BEC4ND1 ionophore in detecting Hg(II) ions. The ESI-BEC4ND1 ionophore that has been developed shows good selectivity, sensitivity, stability, and reproducibility, so the ESI-BEC4ND1 ionophore is promising to be used as a Hg(II) ion detector in the environment.</p>
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Ezzat, Samar, Mona A. Ahmed, Abd El-Galil E. Amr, Mohamed A. Al-Omar, Ayman H. Kamel, and Nagy M. Khalifa. "Single-Piece All-Solid-State Potential Ion-Selective Electrodes Integrated with Molecularly Imprinted Polymers (MIPs) for Neutral 2,4-Dichlorophenol Assessment." Materials 12, no. 18 (September 10, 2019): 2924. http://dx.doi.org/10.3390/ma12182924.
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A novel single-piece all-solid-state ion-selective electrode (SC/ISE) based on carbon-screen printed is introduced. Polyaniline (PANI) is dissolved in a membrane cocktail that contains the same components used for making a conventional ion-selective polyvinyl chloride (PVC) matrix membrane. The membrane, having the PANI, is directly drop-casted on a carbon substrate (screen-printed-carbon electrode). PANI was added to act as an intermediary between the substrate and the membrane for the charge transfer process. Under non-equilibrium sensing mechanism, the sensors revealed high sensitivity towards 2,4-dichlorophenol (DCP) over the linearity range 0.47 to 13 µM and a detection limit 0.13 µm. The selectivity was measured by the modified separate solution method (MSSM) and showed good selectivity towards 2,4-DCP over the most commonly studied ions. All measurements were done in 30 mm Tris buffer solution at a pH 5.0. Using constant-current chronopotentiometry, the potential drift for the proposed electrodes was checked. Improvement in the potential stability of the SPE was observed after the addition of PANI in the sensing membrane as compared to the corresponding coated-wire electrode (membrane without PANI). The applicability of the sensor has been checked by measuring 2,4-DCP in different water samples and the results were compared with the standard HPLC method.
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Abdalla, Nashwa S., Abd El-Galil E. Amr, Aliaa S. M. El-Tantawy, Mohamed A. Al-Omar, Ayman H. Kamel, and Nagy M. Khalifa. "Tailor-Made Specific Recognition of Cyromazine Pesticide Integrated in a Potentiometric Strip Cell for Environmental and Food Analysis." Polymers 11, no. 9 (September 19, 2019): 1526. http://dx.doi.org/10.3390/polym11091526.
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Screen-printed ion-selective electrodes were designed and characterized for the assessment of cyromazine (CYR) pesticide. A novel approach is to design tailor-made specific recognition sites in polymeric membranes using molecularly imprinted polymers for cyromazine (CR) determination (sensor I). Another sensor (sensor II) is the plasticized PVC membrane incorporating cyromazine/tetraphenyl borate ion association complex. The charge-transfer resistance and water layer reached its minimal by incorporating Polyaniline (PANI) solid-contact ISE. The designed electrodes demonstrated Nernstain response over a linear range 1.0 × 10−2–5.2 × 10−6 and 1.0 × 10−2–5.7 × 10−5 M with a detection limit 2.2 × 10−6 and 8.1 × 10−6 M for sensors I and II, respectively. The obtained slopes were 28.1 ± 2.1 (r2 = 0.9999) and 36.4 ± 1.6 (r2 = 0.9991) mV/decade, respectively. The results showed that the proposed electrodes have a fast and stable response, good reproducibility, and applicability for direct measurement of CYR content in commercial pesticide preparations and soil samples sprayed with CYR pesticide. The results obtained from the proposed method are fairly in accordance with those using the standard official method.
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WANG, F. L., and P. M. HUANG. "ION-SELECTIVE ELECTRODE DETERMINATION OF SOLUTION K IN SOIL SUSPENSIONS AND ITS SIGNIFICANCE IN KINETIC STUDIES." Canadian Journal of Soil Science 70, no. 3 (August 1, 1990): 411–24. http://dx.doi.org/10.4141/cjss90-041.
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The feasibility of using a K ion-selective electrode (K-ISE) to monitor changes in solution K concentration in soil suspensions with time, under shaking conditions, was investigated and its significance in kinetics studies of K adsorption was discussed. Factors that affect the efficiency of the K-ISE method include the response time of the electrode, influence of suspended soil particles, shaking speed, and ionic strength of the system. The response time of the K-ISE decreased with increasing K concentration. Moreover, for a system with a solution K concentration greater than 10 mg K L−1, errors resulting from response delays were negligible when, under shaking conditions, observation time intervals were greater than 30 s. The influence of suspended soil particles on the K-ISE method was negligible for soil suspensions with a solution/soil ratio of 50:1 (vol/wt). Shaking significantly influenced K-ISE determination of solution K concentration. The degree of the influence of shaking on the determination of solution K appeared to be related to ionic factors of the systems. Shaking had much less influence on the soil suspensions, the filtrates and mixed CaCl2-KCl solutions than on pure KCl solutions. Satisfactory results were obtained by taking into account the response time, suspended soil particle and shaking speed factors and by adjusting the ionic strength of the calibration system (KCl standard solution series). Key words: Potassium ion-selective PVC membrane electrode, batch technique, kinetics, calibration system, electrode response time, suspended soil particle, shaking speed, ionic strength
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Abdalla, Nashwa, Maha Youssef, H. Algarni, Nasser Awwad, and Ayman Kamel. "All Solid-State Poly (Vinyl Chloride) Membrane Potentiometric Sensor Integrated with Nano-Beads Imprinted Polymers for Sensitive and Rapid Detection of Bispyribac Herbicide as Organic Pollutant." Molecules 24, no. 4 (February 16, 2019): 712. http://dx.doi.org/10.3390/molecules24040712.
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All-solid-state potentiometric sensors were prepared by using polyaniline (PANI) as the solid contact material. A film of PANI (thickness approximately being 0.25 µm) was deposited on a solid substrate (carbon screen printed platform). The PANI layer was subsequently coated with an ion-selective membrane (ISM) containing uniform-sized molecularly imprinted nanoparticles to produce a solid-contact ion-selective electrode (SC/ISE) for bispyribac herbicide (sensor I). In addition, aliquat 336 was also used as an ion exchanger in plasticized PVC membrane (sensor II). The proposed sensors revealed a remarkably improved sensitivity towards bispyribac ions with anionic slopes of −47.8 ± 1.1 (r2 = 0.9995) and −44.4 ± 1.4 (r2 = 0.9997) mV/decade over a linear range 1.0 × 10−2–8.6 × 10−6 M, 1.0 × 10−2–9.0 × 10−6 M and detection limits of 1.33 and 1.81 µg/mL for sensors I and II, respectively.Selectivity of both sensors is significantly high for different common pesticides and inorganic anions. The potential stability of the SC/ISEs was studied using chronopotentiometry. Electrochemical impedance spectrometry was used to understand the charge-transfer mechanisms of the different types of ion-selective electrodes studied. The impedance response of the electrodes was modelled by using equivalent electrical circuits. The sensors were used for a direct measurement of the bispyribac content in commercial herbicide formulations and soil samples collected from agricultural lands planted with rice and sprayed with bispyribac herbicide. The results agree fairly well with data obtained using HPLC method.
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Mohammed, Maha J., Kadhum M. Shabeeb, and Bassam I. Khalil. "Effect of Polyvinyl Pyrrolidone on Polyvinyl Chloride-Graft-Acrylamide Membranes." Engineering and Technology Journal 38, no. 9A (September 25, 2020): 1305–15. http://dx.doi.org/10.30684/etj.v38i9a.1319.
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Polyvinyl-chloride (PVC) was dehydrochlorinated by alkaline-solution (NaOH) in determining molarity (3.0 M) followed by grafting with acrylamide (AM) monomer onto dehydrochlorinated PVC (DHPVC) backbone by free-radical graft copolymerization to produce new grafted polymer referred as graft 3M. Then investigated the effect of polyvinyl pyrrolidone (PVP) addition on the grafted polymer. Membranes from pure PVC, graft 3M, and graft 3M/ PVP were synthesis via a phase inversion method. The successful AM grafting onto PVC was confirmed by characterization of the membranes by Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscope (FESEM) analysis, porosity, pore size, and contact angle measurements. The new synthesis (graft 3M) and (graft 3M/ PVP) membranes show excellent hydrophilicity in compared to pure PVC membranes, confirmed by higher pure water flux (PWF). The graft 3M/ 3wt.% PVP membrane exhibited the highest pure water permeate flux was about 540 L/m2 h at 28 °C of feed temperature and 1bar of pressure, i.e. was improved by about 270 times compared to the unmodified PVC membrane and 2.35 times compared to the graft 3M membrane.
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Witt, Katarzyna, and Elżbieta Radzymińska-Lenarcik. "Characterization of PVC-based polymer inclusion membranes with phosphonium ionic liquids." Journal of Thermal Analysis and Calorimetry 138, no. 6 (November 4, 2019): 4437–43. http://dx.doi.org/10.1007/s10973-019-08912-3.
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Abstract Membrane techniques can be used to separate different compounds, i.e., toxic metal ions from waste waters. As any other method of separation, also this one, based on polymer inclusion membranes (PIMs), has certain limitations. One of them is the stability of membranes. In the present paper, the dependence of the physical and chemical properties on composition of PVC-based polymer inclusion membranes doped with phosphonium ionic liquids (CYPHOS IL 101, CYPHOS IL 104, CYPHOS IL 105 and CYPHOS IL 109) was studied. The thermal stability of investigated membranes was examined by thermogravimetry together with differential thermogravimetry analysis. Obtained results showed that studied PIMs are stable to the temperature of about 170 °C. The membrane morphology was examined by attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy, as well as scanning electron microscopy (SEM). The visibility of all characteristic bands in the ATR-FTIR spectra confirmed the presence of individual components in the membranes: a polymer, a plasticizer and the carriers. It also suggested that there were no signs of the covalent bond formation between the polymer, the plasticizer and the carrier. Only van der Waals or hydrogen bonds could be present. Moreover, in the SEM images of the investigated PIMs a rough surface without pores was observed.
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Luogo, Beatrice Dal Pio, Toufic Salim, Wenjing Zhang, Nanna B. Hartmann, Francesca Malpei, and Victor M. Candelario. "Reuse of Water in Laundry Applications with Micro- and Ultrafiltration Ceramic Membrane." Membranes 12, no. 2 (February 15, 2022): 223. http://dx.doi.org/10.3390/membranes12020223.
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This study compares the performance of a microfiltration membrane, made by silicon carbide (SiC) and an ultrafiltration membrane, made by zirconia (ZrO2), in the treatment of wastewater from a washing machine designed to clean industrial tents. The filtration of deionized water, containing model microplastics (i.e., nylon fiber), was performed. This was followed by the filtration of real wastewater from a single washing cycle of industrial tents, made from polyvinyl chloride (PVC) textile. The filtration parameters of the membranes and physical-chemical parameters of the wastewater, including the concentration of microplastics in the shape of tent fibers (PVC), were calculated before and after filtration. The microfiltration membrane manifested a greater decrease in permeability (95%) compared to the ultrafiltration membrane (37%). The resulting water quality in terms of Total Solids, turbidity, and microplastics concentration was better for the ultrafiltration. This is evident from 99.2% versus 98.55% removal efficiency of microplastics from the laundering wastewater, respectively.
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Atkinson, T. P., M. A. Kaliner, and R. J. Hohman. "Phospholipase C-gamma 1 is translocated to the membrane of rat basophilic leukemia cells in response to aggregation of IgE receptors." Journal of Immunology 148, no. 7 (April 1, 1992): 2194–200. http://dx.doi.org/10.4049/jimmunol.148.7.2194.
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Abstract Aggregation of the high affinity receptor for IgE (Fc epsilon RI) on the surface of mast cells results in the rapid hydrolysis of membrane inositol phospholipids by phospholipase C (PLC). Although at least seven isoenzymes of PLC have been characterized in different mammalian cells, the isoenzyme involved in Fc epsilon RI-mediated signal transduction and the mechanism of its activation have not been demonstrated. We now report that PLC-gamma 1 is translocated to the membrane of mast cells after aggregation of Fc epsilon RI. Activation of rat basophilic leukemia cells, a rat mast cell line, with oligomeric IgE resulted in an increase in PLC activity in washed membrane preparations in a cell free assay containing exogenous [3H]phosphatidylinositol (PI). The increase in PLC activity has the same dose-response to oligomeric IgE as receptor mediated hydrolysis of inositol lipids (PI hydrolysis) in intact cells. Analysis by Western blot probed with anti-PLC-gamma 1 antibody revealed that there is a three- to fourfold increase in PLC-gamma 1 in membranes from activated cells. The increase in PLC activity is augmented a further 20% by the addition of orthovanadate to the incubation medium suggesting that a tyrosine phosphatase is involved in the down-regulation of this phenomenon. These findings demonstrate translocation of PLC-gamma 1 to the membrane following activation of a receptor which does not contain intrinsic tyrosine kinase activity. Activation of PLC-gamma 1 by this pathway may account for Fc epsilon RI-mediated PI hydrolysis.
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Villalba, Martin, Kun Bi, Junru Hu, Yoav Altman, Paul Bushway, Eric Reits, Jacques Neefjes, Gottfried Baier, Robert T. Abraham, and Amnon Altman. "Translocation of PKCθ in T cells is mediated by a nonconventional, PI3-K– and Vav-dependent pathway, but does not absolutely require phospholipase C." Journal of Cell Biology 157, no. 2 (April 15, 2002): 253–63. http://dx.doi.org/10.1083/jcb.200201097.
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PKCθ plays an essential role in activation of mature T cells via stimulation of AP-1 and NF-κB, and is known to selectively translocate to the immunological synapse in antigen-stimulated T cells. Recently, we reported that a Vav/Rac pathway which depends on actin cytoskeleton reorganization mediates selective recruitment of PKCθ to the membrane or cytoskeleton and its catalytic activation by anti-CD3/CD28 costimulation. Because this pathway acted selectively on PKCθ, we addressed here the question of whether the translocation and activation of PKCθ in T cells is regulated by a unique pathway distinct from the conventional mechanism for PKC activation, i.e., PLC-mediated production of DAG. Using three independent approaches, i.e., a selective PLC inhibitor, a PLCγ1-deficient T cell line, or a dominant negative PLCγ1 mutant, we demonstrate that CD3/CD28-induced membrane recruitment and COOH-terminal phosphorylation of PKCθ are largely independent of PLC. In contrast, the same inhibitory strategies blocked the membrane translocation of PKCα. Membrane or lipid raft recruitment of PKCθ (but not PKCα) was absent in T cells treated with phosphatidylinositol 3-kinase (PI3-K) inhibitors or in Vav-deficient T cells, and was enhanced by constitutively active PI3-K. 3-phosphoinositide-dependent kinase-1 (PDK1) also upregulated the membrane translocation of PKCθ, but did not associate with it. These results provide evidence that a nonconventional PI3-K– and Vav-dependent pathway mediates the selective membrane recruitment and, possibly, activation of PKCθ in T cells.
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Arnold, T. P., M. L. Standaert, H. Hernandez, J. Watson, H. Mischak, M. G. Kazanietz, L. Zhao, D. R. Cooper, and R. V. Farese. "Effects of insulin and phorbol esters on MARCKS (myristoylated alanine-rich C-kinase substrate) phosphorylation (and other parameters of protein kinase C activation) in rat adipocytes, rat soleus muscle and BC3H-1 myocytes." Biochemical Journal 295, no. 1 (October 1, 1993): 155–64. http://dx.doi.org/10.1042/bj2950155.
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To evaluate the question of whether or not insulin activates protein kinase C (PKC), we compared the effects of insulin and phorbol esters on the phosphorylation of the PKC substrate, i.e. myristoylated alanine-rich C-kinase substrate (MARCKS). In rat adipocytes, rat soleus muscle and BC3H-1 myocytes, maximally effective concentrations of insulin and phorbol esters provoked comparable, rapid, 2-fold (on average), non-additive increases in the phosphorylation of immunoprecipitable MARCKS. These effects of insulin and phorbol esters on MARCKS phosphorylation in intact adipocytes and soleus muscles were paralleled by similar increases in the phosphorylation of an exogenous, soluble, 85 kDa PKC substrate (apparently a MARCKS protein) during incubation of post-nuclear membrane fractions in vitro. Increases in the phosphorylation of this 85 kDa PKC substrate in vitro were also observed in assays of both plasma membranes and microsomes obtained from rat adipocytes that had been treated with insulin or phorbol esters. These insulin-induced increases in PKC-dependent phosphorylating activities of adipocyte plasma membrane and microsomes were associated with increases in membrane contents of diacylglycerol, PKC-beta 1 and PKC-beta 2. Our findings suggest that insulin both translocates and activates PKC in rat adipocytes, rat soleus muscles and BC3H-1 myocytes.
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Khan, Aamir, Sher Jamal Khan, Waheed Miran, Waqas Qamar Zaman, Alia Aslam, and Hafiz Muhammad Aamir Shahzad. "Feasibility Study of Anaerobic Baffled Reactor Coupled with Anaerobic Filter Followed by Membrane Filtration for Wastewater Treatment." Membranes 13, no. 1 (January 8, 2023): 79. http://dx.doi.org/10.3390/membranes13010079.
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The performance of a Decentralized Wastewater Treatment System (DWTS) comprising an Anaerobic Baffled Reactor (ABR) and an Anaerobic Filter (AF) and Membrane Filtration (MF) module was studied for domestic wastewater treatment. The efficiency of the system was evaluated by running ABR at four different HRTs (14, 12, 10, and 8 h) resulting in COD removal efficiencies of 74, 72, 69, and 65%, respectively. The performance of AF using four different filtration media, i.e., PVC pipe (25 mm), PVC pipe (20 mm), PVC pipe (15 mm), and Kaldnes K3, was determined at optimized HRT (12 h). Among all the filtration media tested, the highest performance efficiency of the system was found with the PVC pipe (20 mm), which showed COD, TP, and TKN removal of 79, 32, and 63%, respectively. The efficacy of the system was proven via significant COD and turbidity removal of 94.6 and 87.2%, respectively, by the combined system.
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Li, Tian, Hongjian Yu, Jing Tian, Junxia Liu, Tonghao Yuan, Shaoze Xiao, Huaqiang Chu, and Bingzhi Dong. "PAC-UF Process Improving Surface Water Treatment: PAC Effects and Membrane Fouling Mechanism." Membranes 12, no. 5 (April 29, 2022): 487. http://dx.doi.org/10.3390/membranes12050487.
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In this study, the water purification effect and membrane fouling mechanism of two powdered activated carbons (L carbon and S carbon) enhancing Polyvinylidene Fluoride (PVDF) ultrafiltration (UF) membranes for surface water treatment were investigated. The results indicated that PAC could effectively enhance membrane filtration performance. With PAC addition, organic removal was greatly enhanced compared with direct UF filtration, especially for small molecules, i.e., the S-UF had an additional 25% removal ratio of micro-molecule organics than the direct UF. The S carbon with the larger particle size and lower specific surface area exhibited superior performance to control membrane fouling, with an operation duration of S-UF double than the direct UF. Therefore, the particle size and pore structure of carbon are the two key parameters that are essential during the PAC-UF process. After filtration, acid and alkaline cleaning of UF was conducted, and it was found that irreversible fouling contributed the most to total filtration resistance, while the unrecoverable irreversible resistance ratio with acid cleaning was greater than that with alkaline cleaning. With PAC, irreversible UF fouling could be relieved, and thus, the running time could be extended. In addition, the membrane foulant elution was analyzed, and it was found to be mainly composed of small and medium molecular organic substances, with 12% to 21% more polysaccharides than proteins. Finally, the hydrophilicity of the elution was examined, and it was observed that alkaline cleaning mainly eluted large, medium, and small molecules of hydrophilic and hydrophobic organic matter, while acid cleaning mainly eluted small molecules of hydrophilic organic matter.
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Doi, Shoichi, Maki Kinoshita, Masahiro Yasukawa, and Mitsuru Higa. "Alkali Attack on Anion Exchange Membranes with PVC Backing and Binder: II Prediction of Electrical and Mechanical Performances from Simple Optical Analyses." Membranes 8, no. 4 (December 14, 2018): 133. http://dx.doi.org/10.3390/membranes8040133.
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Performance of anion exchange membranes (AEMs), including polyvinyl chloride (PVC) as backing and binder, decreases during a repetitive cleaning-in-place (CIP) treatment using alkali. In this study, we have systematically performed two optical analyses, relative total visible (VIS) reflectance and handheld X-ray fluorescence (XRF), for alkali-attacked commercially available AEM (Neosepta® AMX, Tokyo, Japan) with different NaOH immersion conditions (0–1.0 M NaOH at 40–80 °C for 0–168 h). The VIS reflectance and XRF data were then compared with the electrical and mechanical performances (i.e., membrane resistance, proton rejection, amount of fixed-charge sites, and Young’s modulus) of the alkali-attacked AMXs. The result indicated that there are clear linear relationships between their performances and both VIS reflectance and XRF data especially at 40 °C, indicating both optical analyses have a good possibility as a quick diagnosis-in-place (DIP) to predict the resulting performance of the alkali-attacked AMXs. In addition, we also found a clear linear relationship between VIS reflectance and XRF data, so that polyene formations through dehydrochlorination of PVC during alkali attack is one of dominant mechanisms for the performance reduction of the alkali-attacked AMX at 40 °C. These results are promising to be useful for the analysis of ion exchange membranes (IEMs) used in real commercial processes on-site in future.
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Dreskin, S. C., and H. Metzger. "Fc epsilon RI-mediated hydrolysis of phosphoinositides in ghosts derived from rat basophilic leukemia cells." Journal of Immunology 146, no. 9 (May 1, 1991): 3102–9. http://dx.doi.org/10.4049/jimmunol.146.9.3102.
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Abstract Aggregation of the high affinity receptor for IgE (Fc epsilon RI) on mast cells by a polyvalent Ag leads to hydrolysis of phosphoinositides (PI) catalyzed by phospholipase C (PI-PLC). To understand this phenomenon in molecular terms, it is important to obtain active, cell-free preparations. In extensive preliminary studies, we could not demonstrate Fc epsilon RI-mediated activation of PI-PLC in plasma membranes prepared by conventional methods from rat basophilic leukemia cells. We now report a stepwise approach involving preparation of cytoplasts from such cells and then hypotonic lysis of the cytoplasts to obtain active membrane vesicles. These membranes, best described as "ghosts," appear to reseal after losing greater than 90% of their soluble, cytoplasmic components and contain receptors that when aggregated, activate PI-PLC to hydrolyze endogenous phospholipids. Per unit of plasma membrane, the ghosts retain approximately 25% of Fc epsilon RI-mediated stimulation of PI-PLC relative to the cells. This activity requires ATP, magnesium, phosphoenolpyruvate, and, to a limited degree, calcium. Although an adequate amount of phosphatidylinositol biphosphate is present, the predicted spike of (1,4,5)-inositol trisphosphate is not seen, and the predominant inositol phosphate isomer is (1,4)-inositol bisphosphate. This is the first report of Fc epsilon RI-mediated activation of PI-PLC in a cytoplasm-depleted system that demonstrates activation of endogenous enzyme acting on endogenous substrate. In addition, it is the first such report for any receptor of the Ig superfamily.
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Stauffer, Thomas P., and Tobias Meyer. "Compartmentalized IgE Receptor–mediated Signal Transduction in Living Cells." Journal of Cell Biology 139, no. 6 (December 15, 1997): 1447–54. http://dx.doi.org/10.1083/jcb.139.6.1447.
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Several receptor-mediated signal transduction pathways, including EGF and IgE receptor pathways, have been proposed to be spatially restricted to plasma membrane microdomains. However, the experimental evidence for signaling events in these microdomains is largely based on biochemical fractionation and immunocytochemical studies and only little is known about their spatial dynamics in living cells. Here we constructed green fluorescent protein–tagged SH2 domains to investigate where and when IgE receptor (FcεRI)–mediated tyrosine phosphorylation occurs in living tumor mast cells. Strikingly, within minutes after antigen addition, tandem SH2 domains from Syk or PLC-γ1 translocated from a uniform cytosolic distribution to punctuate plasma membrane microdomains. Colocalization experiments showed that the microdomains where tyrosine phosphorylation occurred were indistinguishable from those stained by cholera toxin B, a marker for glycosphingolipids. Competitive binding studies with coelectroporated unlabeled Syk, PLC-γ1, and other SH2 domains selectively suppressed the induction of IgE receptor–mediated calcium signals as well as the binding of the fluorescent SH2 domains. This supports the hypothesis that PLC-γ1 and Syk SH2 domains selectively bind to Syk and IgE receptors, respectively. Unlike the predicted prelocalization of EGF receptors to caveolae microdomains, fluorescently labeled IgE receptors were found to be uniformly distributed in the plasma membrane of unstimulated cells and only transiently translocated to glycosphingolipid rich microdomains after antigen addition. Thus, these in vivo studies support a plasma membrane signaling mechanism by which IgE receptors transiently associate with microdomains and induce the spatially restricted activation of Syk and PLC-γ1.
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Warner, J. A., and D. W. MacGlashan. "Protein kinase C (PKC) changes in human basophils. IgE-mediated activation is accompanied by an increase in total PKC activity." Journal of Immunology 142, no. 5 (March 1, 1989): 1669–77. http://dx.doi.org/10.4049/jimmunol.142.5.1669.
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Abstract We have examined the changes in protein kinase C (PKC) which follow IgE-mediated activation of basophils. Exposure to 0.1 microgram/ml anti-IgE resulted in an increase in total cellular PKC (169 +/- 23% of control, histamine release (HR) = 33 +/- 7%, n = 12) which could be accounted for solely by the increase in membrane-associated PKC. These changes reached a maximum (280 +/- 48%) 1.0 min after challenge and declined to 190 +/- 38% after 5.0 min though histamine release was not complete until 5 to 10 min later. We found a good correlation between the increase in membrane-associated PKC and the eventual release of histamine (rs = 0.902). Donors whose basophils released less than 5% total histamine (n = 3, HR = 3 +/- 1%) showed a partial activation of PKC (173 +/- 18%) though much less than the remaining donors (increase in PKC = 346 +/- 59%, n = 9, HR = 43 +/- 7%). We observed no redistribution of cytosolic PKC at any time following exposure to anti-IgE. In contrast, 0.1 microgram/ml 2-O-tetradecanoyl-phorbol-13-acetate (HR = 36 +/- 3%, n = 3) promoted an increase in total cellular PKC, the loss of 31 +/- 4% of the cytosolic PKC and an 816 +/- 183% increase in membrane-associated PKC. Activation of PKC by anti-IgE was only partially dependent on extracellular calcium. In the absence of calcium, the increase in PKC was approximately 65% (n = 4) of that noted in the presence of 1mM calcium but these levels were sustained over much longer periods, failing to return to base line after 30 min. Higher than normal concentrations of calcium (5 to 10 mM) promoted rapid increases in PKC activity and accelerated the return to base line (back to prechallenge levels by 5 min). Suboptimal concentrations of anti-IgE (0.01 microgram/ml) attenuated the changes in membrane associated PKC and altered the kinetics of the response. The time required to reach maximum activity increased from 1.0 to 5.0 min with a corresponding decrease in the rate at which histamine was released. Higher concentrations of anti-IgE (1.0 microgram/ml) promoted a rapid increase in PKC (maximum increase in PKC = 501 +/- 59%, time = 0.5 min, HR = 28 +/- 2%) followed by an equally rapid return to base line levels.(ABSTRACT TRUNCATED AT 250 WORDS)
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DEMİREL, Elif. "POLİVİNİL KLORÜR (PVC) ULTRAFİLTRASYON MEMBRAN PERFORMANSININ ÇOK DUVARLI KARBON NANOTÜP KATKISI İLE İYİLEŞTİRİLMESİ." Konya Journal of Engineering Sciences 8, no. 3 (September 3, 2020): 479–98. http://dx.doi.org/10.36306/konjes.620662.
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Apgar, J. R. "Association of the crosslinked IgE receptor with the membrane skeleton is independent of the known signaling mechanisms in rat basophilic leukemia cells." Cell Regulation 2, no. 3 (March 1991): 181–91. http://dx.doi.org/10.1091/mbc.2.3.181.
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Crosslinking of the IgE receptor on the surface of rat basophilic leukemia (RBL) cells by multivalent antigen induces an association of these receptors with the detergent-insoluble membrane skeleton. Detergent insolubility of the receptor can also be induced on purified plasma membranes isolated from RBL cells by the use of either IgE oligomers or IgE monomers plus multivalent antigen. The critical event in initiating this interaction between the receptor and the membrane skeleton is cross-linking of the receptor. This association is rapid, and, when triggered by multivalent antigen, it is quickly reversed by the addition of excess monovalent antigen. The fact that this association occurs with the use of purified plasma membranes indicates that all of the components necessary for this interaction are present in the plasma membrane and that intracellular components are not required. Although crosslinking of the receptor activates phospholipase C and phospholipase A2 leading to the generation of several second messengers, none of these signaling mechanisms appears to be involved in IgE receptor interaction with the membrane skeleton. This interaction cannot be induced by phorbol 12-myristate 13-acetate (PMA), ionomycin, or a combination of these two reagents, although this will result in degranulation. Furthermore, receptor detergent insolubility is temperature independent when triggered by multivalent antigen, thus indicating that enzyme-catalyzed reactions are not important. This was verified by the fact that a variety of inhibitors that block phosphatidylinositol metabolism, arachidonic acid metabolism, Ca2+ influx, and protein kinase C (PKC) activation had no effect on antigen-induced association of the receptor with the membrane skeleton. These results indicate that the signaling mechanisms leading to the degranulation response are not involved in the association of the crosslinked receptor with the membrane skeleton.
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Min, Wen, Mingjie Wu, Penghua Fang, Mei Yu, Mingyi Shi, Zhenwen Zhang, and Ping Bo. "Effect of Baicalein on GLUT4 Translocation in Adipocytes of Diet-Induced Obese Mice." Cellular Physiology and Biochemistry 50, no. 2 (2018): 426–36. http://dx.doi.org/10.1159/000494154.
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Background/Aims: Although baicalein has been shown to increase insulin sensitivity in liver of mice, there is no literature available about the effect of baicalein on glucose transporter 4 (GLUT4) translocation from intracellular membrane pools to plasma membranes in adipocytes of diet-induced obese mice. Methods: In the present study, the obese model was induced in mice fed a high fat diet (20% carbohydrates, 21% protein and 59% fat) for 16 weeks. The diet-induced obese mice were given 20mg/kg baicalein intraperitoneally (i.p.) once a day for 21 days. The plasma insulin was measured by enzyme-linked immunosorbent assay. Fasting blood glucose and insulin resistance indexes were measured by glucose tolerance test (GTT). The expression levels of PGC-1α, UCP1, GLUT4, PPARγ, pP38MAPK, pERK and pAKT in adipocytes were determined by quantitative real-time polymerase chain reaction and western blotting. Results: The present findings showed that administration of baicalein decreased pP38MAPK, pERK and PPARγ levels, but enhanced pAKT, PGC-1α and UCP1 contents as well as GLUT4 expression in adipocytes, and reversed high fat diet-induced glucose intolerance, hyperglycemia and insulin resistance in diet-induced obese mice. Moreover, baicalein treatment increased GLUT4 concentration in plasma membranes of adipocytes, i.e. baicalein may prevent insulin resistance through the GLUT4 translocation from intracellular membrane compartments to plasma membranes in adipocytes. Conclusion: These results suggest that baicalein is a powerful and promising agent for treatment of obesity and insulin resistance via Akt/GLUT4 pathway.
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Miura, Katsushi, and Donald W. MacGlashan Jr. "Expression of Protein Kinase C Isozymes in Human Basophils: Regulation by Physiological and Nonphysiological Stimuli." Blood 92, no. 4 (August 15, 1998): 1206–18. http://dx.doi.org/10.1182/blood.v92.4.1206.
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Abstract The expression of protein kinase C (PKC) isozymes in human basophils and the regulation of PKC isozymes during basophil activation by phorbol 12-myristate 13-acetate (PMA) ± ionomycin, f-met-leu-phe (FMLP), and anti-IgE antibody were examined. In human basophils (> 98% purity), PKCβΙ, βΙΙ, δ, and were expressed, PKC was difficult to detect, and PKCγ and η were undetectable. In unstimulated basophils, PKCβI and βII were found primarily in the cytosol fraction (95% ± 3% of total and 98% ± 1%, respectively). Within 5 minutes of stimulation with PMA (100 ng/mL), both PKCβI and βII were translocated to the membrane fraction (85% ± 4% and 83% ± 6%, respectively). In resting cells, 48% ± 3% and 61% ± 10% of PKCδ and , respectively, existed in the membrane fraction. Within 1 minute of stimulation with PMA, 90% ± 6% of PKC was found in the membrane fraction, however, no translocation of PKCδ was apparent. Stimulation with FMLP caused modest translocation (≈20%) of all PKC isozymes by 1 minute, whereas stimulation with anti-IgE antibody led to no detectable changes in PKC location throughout a 15-minute period of measurement. However, concentrations of PMA and ionomycin that alone caused no PKC translocation and little histamine release, together caused significant histamine release but no apparent PKC translocation. Studies with bis-indolylmaleimide analogs showed inhibition of PMA-induced, but not anti–IgE-induced, histamine release. These pharmacological studies suggest that PKC does not play a prodegranulatory role in human basophil IgE-mediated secretion. © 1998 by The American Society of Hematology.
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Miura, Katsushi, and Donald W. MacGlashan Jr. "Expression of Protein Kinase C Isozymes in Human Basophils: Regulation by Physiological and Nonphysiological Stimuli." Blood 92, no. 4 (August 15, 1998): 1206–18. http://dx.doi.org/10.1182/blood.v92.4.1206.416k01_1206_1218.
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The expression of protein kinase C (PKC) isozymes in human basophils and the regulation of PKC isozymes during basophil activation by phorbol 12-myristate 13-acetate (PMA) ± ionomycin, f-met-leu-phe (FMLP), and anti-IgE antibody were examined. In human basophils (> 98% purity), PKCβΙ, βΙΙ, δ, and were expressed, PKC was difficult to detect, and PKCγ and η were undetectable. In unstimulated basophils, PKCβI and βII were found primarily in the cytosol fraction (95% ± 3% of total and 98% ± 1%, respectively). Within 5 minutes of stimulation with PMA (100 ng/mL), both PKCβI and βII were translocated to the membrane fraction (85% ± 4% and 83% ± 6%, respectively). In resting cells, 48% ± 3% and 61% ± 10% of PKCδ and , respectively, existed in the membrane fraction. Within 1 minute of stimulation with PMA, 90% ± 6% of PKC was found in the membrane fraction, however, no translocation of PKCδ was apparent. Stimulation with FMLP caused modest translocation (≈20%) of all PKC isozymes by 1 minute, whereas stimulation with anti-IgE antibody led to no detectable changes in PKC location throughout a 15-minute period of measurement. However, concentrations of PMA and ionomycin that alone caused no PKC translocation and little histamine release, together caused significant histamine release but no apparent PKC translocation. Studies with bis-indolylmaleimide analogs showed inhibition of PMA-induced, but not anti–IgE-induced, histamine release. These pharmacological studies suggest that PKC does not play a prodegranulatory role in human basophil IgE-mediated secretion. © 1998 by The American Society of Hematology.
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Wheeler-Jones, C. P. D., Y. Patel, V. V. Kakkar, and S. Krishnamurthi. "Receptor- and phorbol-ester-mediated redistribution of protein kinase C in human platelets. Evidence that aggregation promotes degradation of protein kinase C." Biochemical Journal 263, no. 3 (November 1, 1989): 969–72. http://dx.doi.org/10.1042/bj2630969.
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Translocation of Ca2+/phospholipid-dependent protein kinase (PKC) activity from cytosolic to membrane fractions was assessed in washed human platelet suspensions. Phorbol myristate acetate (PMA) induced a rapid loss of PKC activity from the cytosolic compartment in stirred platelets, which was not accompanied by measurable increases in membrane-associated activity, but was paralleled by a decrease in total cellular enzyme activity (cytosol plus membrane). When platelet aggregation was prevented by not stirring, (i) cytosolic activity was decreased by PMA, (ii) significant and maintained (1-15 min with PMA) increases in membrane-bound PKC were detected, and (iii) the decline in total enzyme activity was markedly slower. In stirred platelets, total and specific inhibition of PMA-induced aggregation by a fibrinogen-derived peptide (RGDS, i.e. Arg-Gly-Asp-Ser) promoted maximal increases in membrane-associated PKC in the presence of PMA and completely prevented the loss in cellular activity. Thrombin and collagen both induced a decrease in cytosolic PKC and a loss of total activity, but a significant rise in membrane activity was seen only with collagen; ADP had no detectable effect on enzyme distribution. These results demonstrate an agonist-induced redistribution of PKC and indicate that platelet aggregation may play an important role in the proteolysis, and hence persistence, of membrane-associated PKC. This observation has implications for the potency and duration of PKC-mediated responses induced by agonists and exogenous PKC activators.
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Lohwacharin, Jenyuk, Thitiwut Maliwan, Hideki Osawa, and Satoshi Takizawa. "Effects of Ferrihydrite-Impregnated Powdered Activated Carbon on Phosphate Removal and Biofouling of Ultrafiltration Membrane." Water 13, no. 9 (April 24, 2021): 1178. http://dx.doi.org/10.3390/w13091178.
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The presence of multiple contaminant species in surface waters makes surface water treatment difficult to accomplish through a single process. Herein, we evaluated the ability of an integrated adsorption/ultrafiltration (UF) membrane filtration system to simultaneously remove phosphates and dissolved organic matter (DOM). When bare powdered activated carbon (PAC) and PAC impregnated with amorphous ferrihydrite (FHPAC) adsorbents were compared, FHPAC showed a greater adsorption rate and capacity for phosphate. FHPAC had a phosphate adsorption capacity of 2.32 mg PO43−/g FHPAC, even when DOM was present as a competing adsorbate. In a lab-scale hybrid FHPAC-UF system (i.e. integrated adsorption by FHPAC with UF membrane filtration), irreversible membrane fouling was ca. three times lower than that in a PAC-UF system. When membrane fouling in the PAC-UF system was described with pore blockage models, we found that the main cause of fouling was bacterial deposition on the membrane surface. CLSM analysis determined that the chemical composition of foulants in the PAC-UF system included higher proportions of proteins, nucleic acids, and alpha-polysaccharides than that in the FHPAC-UF system. Overall, FHPAC’s ability to undergo ligand exchanges with DOM helped to reduce the nutrients and bacteria that cause biofouling to accumulate on the membrane surface.
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Siegrist, H., and A. Joss. "Review on the fate of organic micropollutants in wastewater treatment and water reuse with membranes." Water Science and Technology 66, no. 6 (September 1, 2012): 1369–76. http://dx.doi.org/10.2166/wst.2012.285.
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A brief review of the fate of micropollutants in membrane-based wastewater treatment due to sorption, stripping, biological degradation/transformation and membrane separation is discussed, to give an overview of these technologies due to the growing importance for water reuse purposes. Compared with conventional activated sludge treatment (CAS) micropollutant removal in membrane bioreactor (MBR) is slightly improved due to complete suspended solids removal and increased sludge age. For discharge to sensitive receiving waters advanced treatment, such as post-ozonation or activated carbon adsorption, is recommended. In water reuse plants nanofiltration (NF) and reverse osmosis (RO) efficiently reject micropollutants due to size exclusions as well as electrostatic and hydrophobic effects reaching potable quality. To remove micropollutants fully, additionally post-ozone or the addition of powdered activated carbon (PAC) have to be applied, which in parallel also reduce NDMA precursors. The concentrate has to be treated if disposed to sensitive receiving waters due to its high micropollutant concentration and ecotoxicity potential. The present review summarizes principles and capabilities for the most important membrane-based applications for wastewater treatment, i.e. porous membranes in MBRs (micro- or ultrafiltration) and dense membrane applications (NF and RO) for water reuse.
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Wang, Zhe, Xiaoguang Zhou, and Jili Feng. "An Innovative Method for Conventional Triaxial Tests of Concrete: Applications of PVC Pipes as a Mould and Sealing Membrane." Advances in Civil Engineering 2020 (August 25, 2020): 1–14. http://dx.doi.org/10.1155/2020/4125428.
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In this paper, we propose an innovative method for conventional triaxial tests of concrete with a confining cell. The polyvinyl chloride (PVC) pipe is used as a mould to cast concrete and also as a membrane to isolate the concrete specimen from oil under confinements. This method is termed as PMM (i.e., PVC pipe is used as a mould and membrane). However, a heat-shrink sleeve is used as a membrane in the traditional test method (TMM). Specimens were made from mortar without coarse aggregates in the present experiment. Under six confinements (0–70 MPa), the conventional triaxial compression tests were performed on ultrahigh-strength (150 MPa) and high-strength (82 MPa) mortar specimens by PMM and TMM. The results indicate the following: (i) there is a characteristic confinement p0; when the confinement is lower than p0, the strength by PMM is higher than that by TMM; on the contrary, when the confinement is higher than p0, the strengths by both methods are almost identical. In this work, p0 is between 0 and 5 MPa. (ii) When the confinement is 5–70 MPa, the relationship between the peak stress of high-strength mortar and confinement is characterized by a monotonically rising straight line; however, a monotonically rising upward convex curve describes the peak stress of ultrahigh-strength mortar related to the confinement. (iii) The residual strength using PMM is significantly higher than that using TMM at zero confinement or lower confinements, but the residual strengths by these two methods are approximately identical at higher confinements. (iv) The transverse cracks appear in the mortar specimen inside the PVC pipe after enduring a triaxial loading using PMM. However, there is no such phenomenon when TMM is applied.
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White, K. N., and H. Metzger. "Translocation of protein kinase C in rat basophilic leukemic cells induced by phorbol ester or by aggregation of IgE receptors." Journal of Immunology 141, no. 3 (August 1, 1988): 942–47. http://dx.doi.org/10.4049/jimmunol.141.3.942.
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Abstract Rat basophilic leukemic cells contain protein kinase C (PKC), 96 +/- 1% of which is located in the cytosol in the resting state. Phorbol ester (PMA), synergistically with calcium ionophore (A23187), caused 55% of the total PKC activity to associate rapidly with membranes where it remained for at least 20 min. When IgE-loaded cells were activated by Ag, maximally 30% of the cytosolic activity associated with membranes within 15 to 30 s, but most of this returned to the cytosol by 2 min. The small amount (3%) of PKC activity that remained associated with the membranes did so for at least 20 min but only if aggregation of the receptors was maintained. PKC translocation correlated with aggregation of receptors both at 30 s and at 10 min. However, only the translocation at 10 min and not that at 30 s correlated with receptor-induced exocytosis. In the absence of extracellular calcium (no exocytosis is observed), translocation at 30 s was diminished by 30% and at 10 min was completely absent. Cells depleted of PKC by 18-h treatment with PMA failed to degranulate in response to PMA and A23187 but responded partially (35%) when receptors were aggregated. We conclude that translocation of PKC is an early event that follows aggregation of IgE receptors but may not be essential for mediating the exocytotic mechanism induced by these receptors.
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Gelband, Craig H. "Renal Vascular Kv and Ca 2+ Channel Alterations in the SHR are Dependent on Protein Kinase C Activity." Hypertension 36, suppl_1 (October 2000): 688. http://dx.doi.org/10.1161/hyp.36.suppl_1.688-d.
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60 It is well established that in renal vascular smooth muscle cells of the SHR there is membrane depolarization, a decrease in Kv current and an increase in Ca 2+ current when compared to control WKY cells. It is also well accepted that protein kinase C (PKC) activity in SHR vascular smooth muscle is increased when compared to the WKY vasculature. The objective of this study was to investigate if the increased vascular PKC activity of the SHR plays a role in the regulation of SHR renal smooth muscle cell Kv and Ca 2+ channels. Basal PKC activity was increased ∼3-fold in the SHR renal arterioles when compared to the WKY (2.2±0.4 vs 6.3±0.6 nmol[ 32 P]/min/mg protein, n=7, P≤0.01). Western blot analysis showed the presence of four different PKC isoforms, α, δ, ε and ζ, in both WKY and SHR renal resistance arterioles. Of the four isoforms, only the levels of PKC-α and ε were significantly increased in the SHR when compared to the WKY. To investigate the influence of PKC on vascular membrane potential, Kv and Ca 2+ current, renal resistance arteriolar cells were treated with PKC inhibitors (staurosporine or Calphostin C,1 μM) or activators (PMA or PDBu, 100 nM) for 1 hour and then subjected to whole cell patch clamp analysis. Interestingly, when SHR renal smooth muscle cells were treated with either PKC inhibitor, the membrane depolarization, decrease in Kv current and increase in Ca 2+ current usually observed were abolished , i.e. the SHR cells electrophysiologically resemble WKY cells. When WKY renal smooth muscle cells were treated with either phorbol ester, they caused membrane depolarization (22±3.5 mV, n=8), a decrease in Kv current (65±8.5%, n=10) and an increase in Ca 2+ current (125±11%, n=9), i.e. WKY cells electrophysiologically resemble SHR cells. These data suggest, that in renal arterioles of the SHR, increased PKC activity plays a role in the regulation of Kv and Ca 2+ channels, which in turn alters membrane potential, intracellular free Ca 2+ concentration and the resting tone of vascular smooth muscle in the kidney. This then would further decrease renal blood flow and exacerbate the hypertensive state.
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Asadi, Hastia, Joerg Uhlemann, Natalie Stranghoener, and Mathias Ulbricht. "Artificial Weathering Mechanisms of Uncoated Structural Polyethylene Terephthalate Fabrics with Focus on Tensile Strength Degradation." Materials 14, no. 3 (January 29, 2021): 618. http://dx.doi.org/10.3390/ma14030618.
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In the past five decades, reinforced coated textile membranes have been used increasingly as building materials, which are environmentally exposed. Thus, their weathering degradation over the service life must be taken into account in design, fabrication, and construction. Regarding such structural membranes, PVC (polyvinylchloride)-coated PET (polyethylene terephthalate) fabric is one of the most common commercially available types. This paper focuses on the backbone of it, i.e., the woven PET fabric. Herein, weathering of uncoated PET, as the load-bearing component of the composite PET-PVC, was studied. This study assessed the uniaxial tensile strength degradation mechanisms of uncoated PET fabric during artificial accelerated weathering tests. For this purpose, exploratory data analysis was carried out to analyze the chemical and physical changes which were traced by Fourier transform infrared spectroscopy and molecular weight measurements. Finally, with the help of degradation mechanisms determined from the aforementioned evaluations, a degradation pathway network model was constructed. With that, the relationship between applied stress, mechanistic variables, structural changes, and performance level responses (tensile strength degradation) was assessed.
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Zheng, Yaoxian, Qiong Wang, Mi Lin, and Zhengbiao Ouyang. "Enhancement of Self-Collimation Effect in Photonic Crystal Membranes Using Hyperbolic Metamaterials." Nanomaterials 12, no. 3 (February 6, 2022): 555. http://dx.doi.org/10.3390/nano12030555.
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Hyperbolic metamaterials (HMMs) exhibit high tunability in photonic devices. This study numerically investigates light propagation in photonic crystal (PhC) membranes containing HMMs. The proposed HMM PhC membranes contain square HMM rods, which comprise dielectric (Si) and metallic (Ag) layers. Owing to their property of subwavelength field localization, HMMs can be applied to PhCs to improve tunability and thus enhance the self-collimation (SC) effect of PhCs. The SC points were obtained in the second HMM PhC band, wherein the nearby dispersion curves change significantly. In addition, the effect of the HMM filling factor (i.e., the ratio of the metal-layer to unit-cell thicknesses) on the SC point frequency is studied. Finally, we demonstrate the efficient control of beam behaviors using HMM PhC membranes while considering the nonlinearity of Ag. The findings of this study confirm that high-performance HMM PhC membranes can be employed in nonlinear all-optical switches, filters, tunable lenses, and other integrated optical devices.
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Galal Eldin, Ahmed, Abd El-Galil E. Amr, Ayman H. Kamel, and Saad S. M. Hassan. "Screen-printed Microsensors Using Polyoctyl-thiophene (POT) Conducting Polymer As Solid Transducer for Ultratrace Determination of Azides." Molecules 24, no. 7 (April 9, 2019): 1392. http://dx.doi.org/10.3390/molecules24071392.
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Two novel all-solid-state potentiometric sensors for the determination of azide ion are prepared and described here for the first time. The sensors are based on the use of iron II-phthalocyanine (Fe-PC) neutral carrier complex and nitron-azide ion-pair complex (Nit-N3−) as active recognition selective receptors, tetradodecylammonium tetrakis(4-chlorophenyl) borate (ETH 500) as lipophilic cationic additives and poly(octylthiophene) (POT) as the solid contact material on carbon screen-printed devices made from a ceramic substrate. The solid-contact material (POT) is placed on a carbon substrate (2 mm diameter) by drop-casting, followed, after drying, by coating with a plasticized PVC membrane containing the recognition sensing complexes. Over the pH range 6-9, the sensors display fast (< 10 s), linear potentiometric response for 1.0 × 10−2–1.0 × 10−7 M azide with low detection limit of 1.0 × 10−7 and 7.7 × 10−8 M (i.e., 6.2–4.8 ng/ml) for Fe-PC/POT/and Nit-N3−/POT based sensors, respectively. The high potential stability and sensitivity of the proposed sensors are confirmed by electrochemical impedance spectroscopy (EIS) and constant-current chronopotentiometry measurement techniques. Strong membrane adhesion and absence of delamination of the membrane, due to possible formation of a water film between the recognition membranes and the electron conductor are also verified. The proposed sensors are successfully applied for azide quantification in synthetic primer mixture samples. Advantages offered by these sensors are the robustness, ease of fabrication, simple operation, stable potential response, high selectivity, good sensitivity and low cost.
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Chen, Yongyue, Guillermo A. Altenberg, and Luis Reuss. "Mechanism of activation of Xenopus CFTR by stimulation of PKC." American Journal of Physiology-Cell Physiology 287, no. 5 (November 2004): C1256—C1263. http://dx.doi.org/10.1152/ajpcell.00229.2004.
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PKA-mediated phosphorylation of the regulatory (R) domain plays a major role in the activation of the human cystic fibrosis transmembrane conductance regulator (hCFTR). In contrast, the effect of PKC-mediated phosphorylation is controversial, smaller than that of PKA, and dependent on the cell type. In the present study, we expressed Xenopus CFTR ( XCFTR) and hCFTR in Xenopus oocytes and examined their responses (i.e., macroscopic membrane conductance) to maximal stimulation by PKC and PKA agonists. With XCFTR, the average response to PKC was approximately sixfold that of PKA stimulation. In contrast, with hCFTR, the response to PKC was ∼90% of the response to PKA stimulation. The reason for these differences was the small response of XCFTR to PKA stimulation. Using the substituted cysteine accessibility method, we found no evidence for insertion of functional CFTR channels in the plasma membrane in response to PKC stimulation. The increase in macroscopic conductance in response to PKC stimulation of XCFTR was due to an approximately fivefold increase in single-channel open probability, with a minor (∼30%) increase in single-channel conductance. The responses of XCFTR to PKC stimulation and of hCFTR to PKA stimulation were mediated by similar increases in Po. In both instances, there were no changes in the number of channels in the membrane. We speculate that in animals other than humans, PKC stimulation may be the dominant mechanism for activation of CFTR.
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Müller, G., and W. Bandlow. "Glucose induces lipolytic cleavage of a glycolipidic plasma membrane anchor in yeast." Journal of Cell Biology 122, no. 2 (July 15, 1993): 325–36. http://dx.doi.org/10.1083/jcb.122.2.325.
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In the yeast Saccharomyces cerevisiae an amphiphilic cAMP-binding protein has been found recently to be anchored to plasma membranes by virtue of a glycolipid structure (Müller and Bandlow, 1991a, 1992). The cAMP-binding parameters of this protein are affected by the lipolytic removal of the glycosylphosphatidylinositol (GPI) membrane anchor by exogenous (G)PI-specific phospholipases C or D (PLC or PLD) (Müller and Bandlow, 1993) suggesting a regulatory role of glycolipidic membrane anchorage. Here we report that transfer of yeast cells from lactate to glucose medium results in the conversion of the amphiphilic form of the cAMP receptor protein into a hydrophilic version accompanied by the rapid loss of fatty acids from the GPI anchor of the [14C]palmitic acid-labeled protein. Analysis of the cleavage site identifies [14C]inositol phosphate as the major product after treatment of the soluble, [14C]inositol-labeled protein with nitrous acid which destroys the glucosamine constituent of the anchor. Together with the observed cross-reactivity of the hydrophilic fragment with antibodies directed against the cross-reacting determinant of soluble trypanosomal variable surface glycoproteins (i.e., myo-inositol-1,2-cyclic phosphate) this demonstrates that, in membrane release, the initial cleavage event is catalyzed by an intrinsic GPI-PLC activated upon transfer of cells to glucose medium. Release from the plasma membrane in soluble form requires, in addition, the presence of high salt or alpha-methyl mannopyranoside, or the removal of the carbohydrate moieties, because otherwise the protein remains associated with the membrane presumably at least in part via its N-glycosidic carbohydrate side chains. The data point to the possibility that cleavage of the anchor could play a role in the transfer of the signal for the nutritional situation to the interior of the cell.
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Warner, J. A., and D. W. MacGlashan. "Signal transduction events in human basophils. A comparative study of the role of protein kinase C in basophils activated by anti-IgE antibody and formyl-methionyl-leucyl-phenylalanine." Journal of Immunology 145, no. 6 (September 15, 1990): 1897–905. http://dx.doi.org/10.4049/jimmunol.145.6.1897.
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Abstract We have compared the transmembrane signals generated in human basophils by two distinct stimuli, anti-IgE antibody and FMLP (f-met peptide). Although both stimuli resulted in the activation of protein kinase C (PKC) and an increase in intracellular free calcium, there were substantial differences between the two which suggested that distinct signal transduction mechanisms were operating. We have confirmed an earlier observation that the cross-linking of IgE led to an increase in membrane PKC activity with no apparent concomitant loss of cytosolic PKC and established that in contrast, the univalent stimulus, f-met peptide, resulted in the canonical translocation of cytosolic PKC to the membrane. Furthermore, unlike anti-IgE-stimulated basophils, there was no clear relationship between the increase in PKC activity and the subsequent release of histamine. Two PKC inhibitors, staurosporine (0.1 to 1 nM) and sphingosine (25 to 50 microM), inhibited anti-IgE induced release, yet, potentiated the release of mediators after a challenge with 1 microM f-met peptide. Both stimuli led to an increase in the intracellular Ca2+ levels that correlated well with the release of histamine, however, the anti-IgE-induced responses were typically only 50% of those required to give equivalent histamine release when f-met peptide initiated release. Pharmacologic evidence suggested that the up-regulation of PKC was required for a full IgE-mediated Ca2+ response and that PKC contributed to the elevated Ca2+ levels that persist for up to 15 min after the addition of anti-IgE. In contrast, the PKC inhibitor, staurosporine, did not affect the initial increase in Ca2+ after the addition of f-met peptide but reduced the rate at which Ca2+ was removed from the cytosol. Experiments with the phorbol ester, PMA, suggested that substantial degranulation can occur in the absence of any increase in intracellular Ca2+. The addition of 10 ng/ml PMA 10 min before the addition of f-met peptide did not affect the magnitude of the initial Ca2+ transient but increased the rate at which Ca2+ levels returned to a stable baseline. Similar pretreatment with PMA almost completely abolished the anti-IgE antibody-induced Ca2+ response. These experiments, together with other previous data, suggest that the activation of PKC is a prodegranulatory component of the IgE-mediated signal transduction pathway, yet serves principally to modulate the Ca2+ signal when f-met peptide initiates release.
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Piiper, A., D. Stryjek-Kaminska, R. Klengel, and S. Zeuzem. "CCK, carbachol, and bombesin activate distinct PLC-beta isoenzymes via Gq/11 in rat pancreatic acinar membranes." American Journal of Physiology-Gastrointestinal and Liver Physiology 272, no. 1 (January 1, 1997): G135—G140. http://dx.doi.org/10.1152/ajpgi.1997.272.1.g135.
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Four different isoforms of phospholipase C-beta (PLC-beta 1-4) have been discovered, raising the important question of whether a distinct receptor activates a single PLC-beta isoenzyme or a subset of PLC-beta isoenzymes. The present study was designed to investigate activation of PLC-beta isoenzymes by three different PLC-activating agonists that bind to different receptor entities, i.e., cholecystokinin octapeptide (CCK-8), bombesin, and carbachol in rat pancreatic acinar membranes. PLC activity was measured using exogenous [3H]phosphatidylinositol 4,5-bisphosphate as substrate. Western blot analysis of pancreatic acinar membranes revealed the presence of PLC-beta 1, -beta 3, -gamma 1, and -delta 1, but not of PLC-beta 2, -beta 4, -gamma 2, and -delta 2. Preincubation of the membranes with anti-PLC-beta 1 or -beta 3 antibody reduced agonist-induced activation of PLC. The order of sensitivity toward inhibition by anti-PLC-beta 1 antibody was CCK-8 > bombesin > carbachol. An opposite order of sensitivity was found for inhibition of PLC activity by anti-PLC-beta 3 antibody (carbachol > bombesin > CCK-8). Anti-PLC-beta 2, -beta 4, -gamma 1, -gamma 2, -delta 1, and -delta 2 antibodies had no effect. Preincubation of the membranes with an antibody raised against the COOH terminus of the alpha-subunit of Gq/11 proteins inhibited PLC activity in response to all three different receptor agonists to a similar extent, whereas anti-Gi alpha 1-2 and anti-Gi alpha 3 antibodies had no effect. In conclusion, the data of the present study indicate that CCK-8 and carbachol activate PLC-beta 1 and PLC-beta 3, respectively, whereas bombesin activates both PLC-beta 1 and PLC-beta 3. Activation of PLC-beta by these receptor agonists is mediated by Gq/11.
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Hashimoto, Gunawan, Wattanachira, Wongrueng, and Takizawa. "Raw Water Storage as a Simple Means for Controlling Membrane Fouling Caused by Inorganic Foulants in River Water in a Tropical Region." Water 11, no. 8 (July 31, 2019): 1592. http://dx.doi.org/10.3390/w11081592.
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Natural waters in tropical countries are turbid and rich in inorganic substances such as iron and manganese. Hence, membrane fouling by these inorganic substances is the most serious problem in membrane filtration processes for potable water production. This study aimed to assess raw water storage as a simple but effective means for controlling membrane fouling in the filtration of river water in a tropical country. Raw water taken from the Ping River in Chiang Mai, Thailand, in different seasons, was either immediately filtered or stored in a tank for two days before filtration through a polyvinylidene difluoride (PVDF) membrane with a nominal pore size of 0.1 μm. The turbidity and particulate organic carbon (POC) in the raw water were reduced by storage, while dissolved manganese was oxidized during the storage period. Although the amounts of metallic substances retained on membranes were larger than those of silica and organic matter, their contribution to the fouling resistance was found to be less than silica and organic carbon. The fouling analysis using hydraulically irreversible fouling index (HIFI) was found to be not able to measure the effects of storage when the initial flux increased. Hence, the ratio of the hydraulically reversible fouling index (HRFI) to the total fouling index (TFI), i.e., HRFI/TFI, was proposed to elucidate the effects of raw water storage on membrane fouling, which was manifest during the early stage of membrane filtration operation.
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Abd Hakim, S., Krista Tarigan, Manihar Situmorang, and Timbangen Sembiring. "Synthesis of Urea Sensors using Potentiometric Methods with Modification of Electrode Membranes Indicators of ISE from PVA-Enzymes Coating PVC-KTpClPB." Journal of Physics: Conference Series 1120 (November 2018): 012024. http://dx.doi.org/10.1088/1742-6596/1120/1/012024.
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Sakai, Hiroyasu, Tomona Hirano, Yoshihiko Chiba, and Miwa Misawa. "Acetylcholine-induced phosphorylation and membrane translocation of CPI-17 in bronchial smooth muscle of rats." American Journal of Physiology-Lung Cellular and Molecular Physiology 289, no. 6 (December 2005): L925—L930. http://dx.doi.org/10.1152/ajplung.00054.2005.
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A translocation of protein kinase C (PKC) from cytosol to plasma membrane has been reported as an association with agonist-induced Ca2+ sensitization in smooth muscle contraction. Therefore, it is possible that a downstream target of PKC, CPI-17 [PKC-potentiated inhibitory protein for heterotrimeric myosin light chain (MLC) phosphatase of 17 kDa], might also be translocated to membrane when activated. To confirm this hypothesis, cytosolic and membrane CPI-17 was measured in acetylcholine (ACh)- and high-K+ depolarization-stimulated bronchial smooth muscle of rats. An active form of CPI-17, i.e., Thr38-phosphorylated CPI-17, was also measured in cytosolic and membrane fractions. Immunoblot analyses demonstrated a translocation of CPI-17 from cytosolic to membrane fraction by ACh, but not high-K+ depolarization, stimulation in time- and concentration-dependent manners. Interestingly, phosphorylated CPI-17 was detected only in membrane fractions in the ACh-stimulated tissues. However, in the high-K+ depolarization-stimulated tissues, phosphorylated CPI-17 was not detected both in membrane and cytosolic fraction. To estimate downstream of activated CPI-17, immunoblotting for phosphorylated MLC was performed in ACh- or high-K+ depolarization-stimulated tissues. ACh- and high-K+ depolarization-induced phosphorylation of MLC was observed in its contraction-dependent manner. In conclusion, we, for the first time, suggested that CPI-17 is translocated and phosphorylated by ACh, but not high-K+ depolarization, in rat bronchial smooth muscle. ACh-induced translocation and phosphorylation of CPI-17 might be caused via the activation of muscarinic receptor.
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Stoica, Anca-Iulia, Clara Viñas, and Francesc Teixidor. "History of Cobaltabis(dicarbollide) in Potentiometry, No Need for Ionophores to Get an Excellent Selectivity." Molecules 27, no. 23 (November 29, 2022): 8312. http://dx.doi.org/10.3390/molecules27238312.
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This work is a mini-review highlighting the relevance of the θ metallabis(dicarbollide) [3,3′-Co(1,2-C2B9H11)2]− with its peculiar and differentiating characteristics, among them the capacity to generate hydrogen and dihydrogen bonds, to generate micelles and vesicles, to be able to be dissolved in water or benzene, to have a wide range of redox reversible couples and many more, and to use these properties, in this case, for producing potentiometric membrane sensors to monitor amine-containing drugs or other nitrogen-containing molecules. Sensors have been produced with this monoanionic cluster [3,3′-Co(1,2-C2B9H11)2]−. Other monoanionic boron clusters are also discussed, but they are much fewer. It is noteworthy that most of the electrochemical sensor species incorporate an ammonium cation and that this cation is the species to be detected. Alternatively, the detection of the borate anion itself has also been studied, but with significantly fewer examples. The functions of the borate anion in the membrane are different, even as a doping agent for polypyrrole which was the conductive ground on which the PVC membrane was deposited. Apart from these cases related to closo borates, the bulk of the work has been devoted to sensors in which the θ metallabis (dicarbollide) [3,3′-Co(1,2-C2B9H11)2]− is the key element. The metallabis (dicarbollide) anion, [3,3′-Co(1,2-C2B9H11)2]−, has many applications; one of these is as new material used to prepare an ion-pair complex with bioactive protonable nitrogen containing compounds, [YH]x[3,3′-Co(1,2-C2B9H11)2]y as an active part of PVC membrane potentiometric sensors. The developed electrodes have Nernstian responses for target analytes, i.e., antibiotics, amino acids, neurotransmitters, analgesics, for some decades of concentrations, with a short response time, around 5 s, a good stability of membrane over 45 days, and an optimal selectivity, even for optical isomers, to be used also for real sample analysis and environmental, clinical, pharmaceutical and food analysis.
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Baldassarre, M., A. Dragonetti, P. Marra, A. Luini, C. Isidoro, and R. Buccione. "Regulation of protein sorting at the TGN by plasma membrane receptor activation." Journal of Cell Science 113, no. 4 (February 15, 2000): 741–48. http://dx.doi.org/10.1242/jcs.113.4.741.
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We show that in the rat basophilic leukemia cell line RBL, the physiological stimulation of the IgE receptor or direct activation of PKC leads to the missorting of proteins to the plasma membrane, diverting them from their normal intracellular destination. This is demonstrated for two classes of proteins that are normally targeted to the secretory lysosomes via completely different mechanisms, i.e. proteoglycans and the aspartic protease cathepsin D. In the latter case, normal processing of the enzyme is also affected, leading to secretion of the immature form of cathepsin. The present study shows how completely different sorting mechanisms, such as those for delivering proteoglycans and cathepsin D to secretory lysosomes, might share common regulatory signals and are similarly affected when the levels of these signals are perturbed. Finally, protein kinase C appears to be a major player in the signal transduction pathways, leading to proteoglycan and cathepsin D missorting.
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Chang, E. Y., Z. Szallasi, P. Acs, V. Raizada, P. C. Wolfe, C. Fewtrell, P. M. Blumberg, and J. Rivera. "Functional effects of overexpression of protein kinase C-alpha, -beta, -delta, -epsilon, and -eta in the mast cell line RBL-2H3." Journal of Immunology 159, no. 6 (September 15, 1997): 2624–32. http://dx.doi.org/10.4049/jimmunol.159.6.2624.
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Abstract The rat basophilic leukemic (RBL-2H3) cell line was stably transfected with the endogenously expressed Ca2+-dependent protein kinase C-alpha (PKC-alpha) and -betaI and the Ca2+-independent delta and epsilon isoforms to study their functional roles. In addition, the Ca2+-independent PKC-eta was expressed. All transfected PKC isoforms translocated to the membrane-containing fraction in response to aggregation of the IgE-sensitized high affinity receptor for IgE (Fc epsilonRI) with the Ag dinitrophenyl(25)-BSA. All PKC transfectants, except PKC-eta, showed increased proliferative responses, and aggregation of Fc epsilonRI further enhanced the rate of proliferation. The PKC transfectants also showed increased phosphoinositide hydrolysis in response to Ag aggregation of receptors. No marked differences in the Ca2+ responses of the transfectants to Ag or thapsigargin were observed. Overexpression of PKC-alpha or -epsilon specifically inhibited receptor-dependent cytosolic phospholipase A2 (cPLA2) activity, whereas this activity was enhanced in the PKC-betaI transfectant. Analysis of the secretory response revealed that overexpression of PKC-betaI and -eta significantly enhanced secretion. A broad spectrum of cytokine mRNAs was detected in all transfectants, and overexpression of PKC-betaI significantly enhanced the receptor-dependent production of IL-2 and IL-6 mRNA. These studies identify PKC-alpha and -epsilon as negative regulators of cPLA2 activity and demonstrate the importance of PKC-beta as a positive modulator of secretion, cPLA2 activity, and cytokine production in this mast cell line.
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Sarasidis, Vasilis C., Konstantinos V. Plakas, and Anastasios J. Karabelas. "A Pilot Study of a Hybrid Process Involving In Situ Regenerated Activated Carbon, Membrane Separation and Advanced Oxidation for Water Pollution Abatement." Journal of Chemical Engineering Research Updates 8 (December 5, 2021): 60–72. http://dx.doi.org/10.15377/2409-983x.2021.08.5.
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The assessment of a pilot-scale hybrid system coupling powdered activated carbon (PAC) adsorption with membrane ultrafiltration (UF), in respect of activated carbon regeneration and organic micropollutant removal, was investigated in this study. Field tests with two adsorbents (i.e. a commercial PAC and a PAC-Fe(II) composite), conducted in the premises of Thessaloniki Water Treatment Plant, demonstrated the high efficiency of the combined PAC/UF process. Regeneration efficiencies varying between approximately 95% and 110%, complete diclofenac (DCF) degradation and rather moderate mineralization (TOC removal) rates of up to 47%, can be achieved by UVC/H2O2 or photo-Fenton oxidation after 4 hours of treatment; this performance is attributed to the in situ generation of reactive oxidant species by photolysis of H2O2, which seems to enhance the process effectiveness. Among the two adsorbent materials tested, composite PAC-Fe(II) exhibited a higher DCF adsorption capacity than the original PAC, probably due to the improved chemisorption and/or the electrostatic attractive interactions between the negatively charged DCF molecules and the positively charged iron species, at neutral pH. Furthermore, a rather insignificant effect of PAC-Fe(II) loading on the regeneration efficiency was observed. The advantages of totally controlled H2O2 dosages and short operating times render the hybrid PAC/UF system a promising alternative to conventional and advanced drinking water purification methods.
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Tubiana, Thibault, Ian Sillitoe, Christine Orengo, and Nathalie Reuter. "Dissecting peripheral protein-membrane interfaces." PLOS Computational Biology 18, no. 12 (December 14, 2022): e1010346. http://dx.doi.org/10.1371/journal.pcbi.1010346.
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Peripheral membrane proteins (PMPs) include a wide variety of proteins that have in common to bind transiently to the chemically complex interfacial region of membranes through their interfacial binding site (IBS). In contrast to protein-protein or protein-DNA/RNA interfaces, peripheral protein-membrane interfaces are poorly characterized. We collected a dataset of PMP domains representative of the variety of PMP functions: membrane-targeting domains (Annexin, C1, C2, discoidin C2, PH, PX), enzymes (PLA, PLC/D) and lipid-transfer proteins (START). The dataset contains 1328 experimental structures and 1194 AphaFold models. We mapped the amino acid composition and structural patterns of the IBS of each protein in this dataset, and evaluated which were more likely to be found at the IBS compared to the rest of the domains’ accessible surface. In agreement with earlier work we find that about two thirds of the PMPs in the dataset have protruding hydrophobes (Leu, Ile, Phe, Tyr, Trp and Met) at their IBS. The three aromatic amino acids Trp, Tyr and Phe are a hallmark of PMPs IBS regardless of whether they protrude on loops or not. This is also the case for lysines but not arginines suggesting that, unlike for Arg-rich membrane-active peptides, the less membrane-disruptive lysine is preferred in PMPs. Another striking observation was the over-representation of glycines at the IBS of PMPs compared to the rest of their surface, possibly procuring IBS loops a much-needed flexibility to insert in-between membrane lipids. The analysis of the 9 superfamilies revealed amino acid distribution patterns in agreement with their known functions and membrane-binding mechanisms. Besides revealing novel amino acids patterns at protein-membrane interfaces, our work contributes a new PMP dataset and an analysis pipeline that can be further built upon for future studies of PMPs properties, or for developing PMPs prediction tools using for example, machine learning approaches.