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1.
The swelling of five types of Sephadex that are either nonionic (G) or possess one of four different ionic groups [sodium carboxymethyl (CM), sodium sulfopropyl (SP), diethyl-aminoethyl chloride (DEAE), diethyl - (2-hydroxypropyl) aminoethyl chloride (QAE)] in the same skeleton of the molecule has been studied by picture analysis and by calorimetry. Inducing dissociation of the ionic group in the polymer skeleton increased the water swelling. By the addition of sodium chloride, the maximum swelling volume of nonionic Sephadex was only slightly decreased. However, that of ionic polymers was considerably decreased. The variation of the apparent first-order rate constant of the swelling and that of the maximum swelling volume show the same tendency. The maximum heats of swelling were 93.2 ± 7.1 J g?1 for G, 128.8 ± 9.1 J g?1 for CM, 92.3 ± 8.0 J g?1 for SP, 68.8 ± 10.5 J g?1 for DEAE, and 67.0 ± 7.2 J g?1 for QAE and did not depend on the concentration of sodium chloride. From the results obtained, we conclude that the nonionic Sephadex swells only by hydration but that ionic Sephadexes swell mainly by the osmotic pressure due to the counterions of the ionic groups and that the swelling ratio is not dependent on the kinds of ions but on the ionic concentration. Most of the water in the gels of ionic Sephadexes is free water that does not interact with the Sephadexes. © 1993 John Wiley & Sons, Inc.  相似文献   

2.
The swelling of five types of spherical crosslinked dextrans (Sephadex) that are either nonionic (G) or ionic [carboxymethyl (CM), sulphopropyl (SP), diethylaminoethyl (DEAE), and diethyl-(2-hydroxypropyl)aminoethyl (QAE)] in the same skeleton has been studied in water at different dissolved oxygen concentrations by microscopic observation and by dilatometry. The maximum specific volume, Vmax/V0 obtained by microscopic observation increased with the lowered dissolved oxygen concentration for each Sephadex. The change of the maximum specific volume was closely related to the changes of the dissolved oxygen concentrations. The maximum changes of the total volume took the larger negative values at the lower dissolved oxygen concentration. The effect of the difference in the dissolved oxygen on the change of the total volume with swelling was closely related to the viscosity B coefficient of the Jones-Dole equation. From these results, we conclude that the structure of water on the inside of the gel differs from that on the outside of the gel. © 1995 John Wiley & Sons, Inc.  相似文献   

3.
The kinetics of the swelling of sodium polyacrylate (NaPA), a hydrophilic polymer, was studied gravimetrically, by microscopic observation, and calorimetrically. The swelling process followed first-order kinetics and the rate constant was of the order of 10?2 s?1. The gravimetric method, however, was not useful for kinetic studies. The rate constant was depressed by the addition of sodium chloride. The activation energy of the swelling was 46.0 ± 6.2 (kJ mol?1) and decreased with the increase in sodium chloride concentration. In acid solution, the activation energy was almost the same as that in water. The heat of the swelling was 196 ± 17 J g?1 and did not vary with the addition of sodium chloride. © 1993 John Wiley & Sons, Inc.  相似文献   

4.
We present mechanically strong macroporous, squeezable dextran cryogels as a column filling material for the removal and separation of binary organic dye and pesticide mixtures from aquatic medium. Dextran cryogels were prepared from aqueous solutions of dextran of various molecular weights (MWs) in the presence of 20 to 50 mol% divinyl sulfone (DVS) as a cross-linker at −18°C. The cryogels have interconnected irregular pores of 100 μm in sizes, and exhibit 69-84% reversible squeezability without damaging the 3D dextran network. Their total open pore volumes (6.3-10 mL g−1), weight swelling ratios in water (1380%-2200%), and mechanical parameters could easily be adjusted by both DVS mol% and MW of dextran. Dextran cryogel with the highest modulus (3.8 ± 0.5 MPa), compressive stress (8 ± 2 MPa) and plateau stress (0.46 ± 0.04 MPa) was obtained at 50 mol% DVS using dextran with a MW of 15 to 25 kg·mol−1. Dextran cryogels are hydrolysable at pH = 1 and 9 but stable at 7.4 independent on both the degree of cross-linking and MW of dextran. At below 50 mol% DVS, they are blood compatible and possess slight thrombogenic effect with blood clotting index value of 98% ± 5%. They are also capable to separate binary dye and pesticide mixtures from aqueous solutions via ionic interactions.  相似文献   

5.
Permeation of sodium chloride and glucose through polydimethylsiloxane‐poly(N‐isopropylacrylamide) (PDMS‐PNIPAAm) interpenetrating polymer networks (IPNs) of two different microstructures was investigated. We have successfully developed small‐molecule permeable IPNs, by modifying PDMS film structure. A group of PDMS films was prepared using conventional solvent casting (SC) method and another group produced by introducing oil, followed by SC and leaching the oil out (SCOL method). Scanning electron microscopy (SEM) and attenuated total reflection fourier transformer infrared (ATR‐FTIR) spectroscopy results confirmed the presence of PNIPAAm in the SC and SCOL IPNs. Results obtained from spectra of differential scanning calorimetry (DSC) showed that these IPNs had a phase transition temperature at about 32°C. Permeation measurements showed that the presence of PNIPAAm as the second phase in the IPN, improved the permeability of PDMS film. According to the results, maximum permeation coefficient was related to SCOL IPN containing 15.8% ± 0.3%PNIPAAm, at 23°C (5.98 × 10?7 ± 7.93 × 10?9 cm2/s for sodium chloride and 3.6 × 10?7 ± 7 × 10?9 cm2/s for glucose). These results suggested that these PDMS‐PNIPAAm IPNs with sodium chloride and glucose permeability may be further developed as ophthalmic biomaterials or corneal replacements. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

6.
A stable and soapless latex of 2‐diethyl‐aminoethyl (DEAE)–dextran–methyl methacrylate (MMA) graft copolymer (DDMC) was developed for nonviral gene delivery vectors (complex between polycation and nucleic acid). DDMC was newly prepared using MMA and DEAE–dextran. Following a transfection protocol, transfection of HEK 293 cells by DDC1, DDC2, and DDC3 samples was carried out using plasmid DNA. With the transfection efficiency determined using the X‐Gal staining method, a higher value of 5 times or more was confirmed for DDMC samples DDC1 and DDC2 (but not for DDC3) than for the starting DEAE–dextran hydrochloride. The absorption spectrum shift at around 3400 cm?1 of the complexes between DDMC and DNA may support the formation of more compact structures by a Coulomb force between the phosphoric acid of DNA and the DEAE group of DEAE–dextran, concluding in DNA condensation. The specifically designed molecular structure of DDMC to ensure easy entry of DNA into cells needs not only a positive charge and a hydrophilic–hydrophobic microseparated domain but also more compact structures for transfection steps. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 9–14, 2005  相似文献   

7.
BACKGROUND: Supercritical water oxidation (SCWO) of dyehouse waste‐water containing several organic pollutants has been studied. The removal of these organic components with unknown proportions is considered in terms of total organic carbon concentration (TOC), with an initial value of 856.9 mg L?1. Oxidation reactions were performed using diluted hydrogen peroxide. The reaction conditions ranged between temperatures of 400–600 °C and residence times of 8–16 s under 25 MPa of pressure. RESULTS: TOC removal efficiencies using SCWO and hydrothermal decomposition were between 92.0 and 100% and 6.6 and 93.8%, respectively. An overall reaction rate, which consists of hydrothermal decomposition and the oxidation reaction, was determined for the hydrothermal decomposition of the waste‐water with an activation energy of 104.12 ( ± 2.6) kJ mol?1 and a pre‐exponential factor of 1.59( ± 0.5) × 105 s?1. The oxidation reaction rate orders for the TOC and the oxidant were 1.169 ( ± 0.3) and 0.075 ( ± 0.04) with activation energies of 18.194 ( ± 1.09) kJ mol?1, and pre‐exponential factor of 5.181 ( ± 1.3) L0.244 mmol?0.244 s?1 at the 95% confidence level. CONCLUSION: Results demonstrate that the SCWO process decreased TOC content by up to 100% in residence times between 8 and 16 s under various reaction conditions. The treatment efficiency increased remarkably with increasing temperature and the presence of excess oxygen in the reaction medium. Color of the waste‐water was removed completely at temperatures of 450 °C and above. Copyright © 2010 Society of Chemical Industry  相似文献   

8.
Adsorption of iron ions from diluted solutions (10?5–10?4 mol/L) of iron(III) chloride on macroporous glass (average pore radius 14.5 ± 0.6 nm) produced from sodium borosilicate glass is investigated. It is shown that the adsorption isotherm in the studied concentration range is in compliance with the Langmuir type. The limiting adsorption in the monomolecular layer and the adsorption equilibrium constant are determined.  相似文献   

9.
Greenhouse gases emitted into the atmosphere by burning of fossil fuels cause global warming. One option is obtaining biodiesel. Nannochloropsis oculata was cultured under different light intensities and reactors at 25°C for 21 days with f/2 medium to assess their effects on cell density, lipid, and fatty acids (FAs). N. oculata improved cell density on fed-batch glass tubular reactor (7 L) at 200 μmol E m−2 s−1, yielding 3.5 × 108 cells ml−1, followed by fed-batch Erlenmeyer flask (1 L) at 650 μmol E m−2 s−1 with 1.7 × 108 cells ml−1. The highest total lipid contents (% g lipid × g dry biomass−1) were 44.4 ± 0.8% for the reactor (1 L) at 650 μmol E m−2 s−1 and 35.2 ± 0.2% for the tubular reactor (7 L) at 200 μmol E m−2 s−1, until twice as high compared with the control culture (Erlenmeyer flask 1 L, 80 μmol E m−2 s−1) with 21.2 ± 1%. Comparing the total lipid content at 200 μmol E m−2 s−1, tubular reactor (7 L) and reactor 1 L achieved 35.2 ± 0.2% and 28.3 ± 1%, respectively, indicating the effect of shape reactor. The FAs were affected by high light intensity, decreasing SFAs to 2.5%, and increased monounsaturated fatty acids + polyunsaturated fatty acids to 2.5%. PUFAs (20:5n-3) and (20:4n-3) were affected by reactor shape, decreasing by half in the tubular reactor. In the best culture, fed-batch tubular reactor (7 L) at 200 μmol E m−2 s−1 contains major FAs (16:0; 38.06 ± 0.16%), (16:1n-7; 30.74 ± 0.58%), and (18:1n-9; 17.15 ± 0.91%).  相似文献   

10.
BACKGROUND: The development of carriers with biocompatible surfaces are required to meet the needs in animal cell culture. In this work, poly (ethylene terephthalate) (PET) fibrous scaffold surfaces were chemically modified to introduce diethylaminoethyl (DEAE) groups. A packed‐bed bioreactor with DEAE‐conjugated PET fibrous scaffolds was investigated for continuous production of HBsAg by r‐CHO cells. RESULTS: The changes of surface properties were characterized by surface hydrophilicity, Attenuated total reflectance (ATR) analysis, element measurement, and scanning electron microscopy. The results showed that this treatment could improve surface hydrophilicity and roughness. Using an r‐CHO cell line as model cells, the feasibility of the DEAE‐conjugated PET fibrous scaffold in animal cell culture was evaluated by means of cell attachment efficiency measurement, MTT (3‐(4,5)‐dimethylthiathiazo(‐z‐yl)‐3,5‐di‐phenytetrazoliumromide) assay, and scanning electron microscopy observation. Enhancement of cell attachment and proliferation was exhibited in the cell culture on DEAE‐conjugated PET fibrous scaffolds. r‐CHO cells were cultured for continuous HBsAg production in a packed‐bed bioreactor with DEAE‐conjugated PET fibrous scaffolds. A cell density of 1.2 × 107 cells mL?1 working volume, cell viability of 92.8% and maximum HBsAg concentration of 3.1 mg L?1 were achieved. CONCLUSION: The packed‐bed bioreactor system with DEAE‐conjugated PET fibrous scaffolds has the potential for industrial animal cell culture application. Copyright © 2008 Society of Chemical Industry  相似文献   

11.
BACKGROUND: When organic matter is limiting for biological nutrient removal (BNR) from wastewater, external organic carbon can be added to a wastewater treatment plant (WWTP). This increases the overall treatment cost, so the choice of substrate is critical. The effect of using ethanol as the carbon source for BNR is investigated. RESULTS: The results clearly showed that using ethanol as a carbon source is a promising strategy for removing nutrients from wastewater. Effluent concentrations of 3.0 mg total nitrogen (TN) L?1 (96% N removal efficiency) and 0.05 mg phosphate (P‐PO4) L?1 (99.9% P removal efficiency) were obtained. Furthermore, tests performed in order to identify the carbon source used by polyphosphate‐accumulating organisms (PAOs) showed that the phosphorus release/carbon uptake ratio using ethanol (0.41 mmol P mmol?1 C) was slightly lower than that with acetate (0.50 mmol P mmol?1 C) but close to that with propionate (0.42 mmol P mmol?1 C). CONCLUSION: Therefore, taking into account the results presented for ethanol‐acclimatised biomass and the fact that the cost of ethanol is lower than that of acetate or propionate, ethanol can be considered as an alternative carbon source if one is needed in a WWTP. Copyright © 2007 Society of Chemical Industry  相似文献   

12.
Owing to its well-known high complexing power toward Al3+ ion, fluoride ion is able to increase the solubility of alumina in alkali chloride melts. To determine the extent of this effect, the formation of aluminium(III) fluoro-complexes was studied potentiometrically in LiCl-KCl eutectic at 470°. But the sodium fluoride addition appeared to produce not only the complexation effect but also a mineralization effect on alumina. So, the thermodynamical stability of alumina formed in this melt by precipitation from aluminium chloride with carbonate ion (oxide anion donor) depends on the fluoride ion concentration. These two effects explain the solubility variation of alumina in the LiCl-KCl eutectic + NaF mixtures. A pF? - pO2? diagram, which represents the stability area of the various aluminium (III) species is established, and leads to some conclusions concerning the electrowinning of aluminium from molten chloride melts.The cumulative formation constants of the aluminium(lII) fluoro-complexes (AlF3?ii) have been obtained, whose values are the following: 2.5 ± 0.4, 4.7 ± 0.6, 5.7 ± 0.5, 7.5 ± 0.4, 8.0 ± 0.5, 9.0 ± 0.6, respectively for i = 1, 2, 3, 4, 5 and 6. It has been shown that oxyfluoride species such as AlOF1?ji does not exist. The solubility products of gamma and alpha-alumina have been determined and are equal to 10?42.9 and 10?44.0 respectively (all the constants are given in the molality scale). They differ widely from the solubility product of the alumina obtained in the absence of fluoride ion, ie 10?27.4.  相似文献   

13.
Oxidation of aqueous solution of C.I. Basic Blue 41 (BB41), which is model azo dye pollutants, was studied in a continuous-flow reactor that was operated between 400 and 650 °C at a fixed pressure of 25 MPa. The total organic carbon (TOC) concentration of BB41 was in the range of 30.60 and 152.97 mmol/L in the feed stock solution. Hydrogen peroxide (H2O2) was used as an oxygen source and the oxidant concentrations were between 73.53 and 489.64 mmol/L in the feed stock solution. The results demonstrated that supercritical water oxidation (SCWO) process decreases the TOC up to 99.87% in very short reaction times (at residence times of 9–19 s). According to the wastewater and oxidant concentrations, the global rate expression was regressed from the complete set of data for each dye solution. As a result of regression analysis, the reaction rate expression for the oxidation of BB41 was determined with the activation energy of 18.88 (±0.9) kJ/mol and the pre-exponential factor of 2.8 (±0.5) mmol?0.16 L0.16 s?1; and the reaction orders for BB41 (based on TOC) and the oxidant were 0.84 (±0.03) and 0.32 (±0.05) in a 95% confidence level.  相似文献   

14.
The culture conditions for glutamate decarboxylase (GAD) production under submerged fermentation by Streptococcus salivarius ssp. thermophilus were investigated. The results indicated the optimum culture medium was composed as follows: 15.0 g L?1 of peptone, 12.5 g L?1 of beef extract, 12.5 g L?1 of sucrose, 1.03 g L?1 of dipotassium hydrogen phosphate, 5 g L?1 of sodium acetate, 2 g L?1 of ammonium dibasic citrate, 2.12 g L?1 of calcium chloride, 1 g L?1 of Tween 80, and initial pH 6.79. The optimum culture temperature and time were 37 °C and 12 h, respectively. Under these conditions, GAD production was 257.46 ± 5.12 U, which was about 1.45‐fold that of Man–Rogosa–Sharpe broth. Copyright © 2008 Society of Chemical Industry  相似文献   

15.
Ultrafiltration membrane based on polyacrylonitrile prepared by phase inversion method using zinc chloride as an additive showed more than 90% rejection for BSA and 90–110 lm?2 h?1 water flux. The surface modification of this membrane was studied using ethanolamine, triethylamine, sodium hydroxide, and potassium hydroxide solutions. The effect of base treatment time and temperature on water flux and rejection was investigated. The membranes exhibited swelling by NaOH treatment followed by deswelling by HCl post‐treatment, similar to pH responsive membranes. The treatment by organic as well as inorganic bases improved water flux with a slight lowering in BSA rejection by dead‐end mode type treatment. A 230% increase in water flux was achieved by sodium hydroxide treatment in crossflow mode without a noticeable pore swelling by SEM. The contact angle of the modified membranes was decreased as compared to the unmodified one indicating appreciable surface modification. As the treatment time or temperature increased, the ESCA analysis showed increased population of Na‐carboxylate groups. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4378–4385, 2006  相似文献   

16.
目的探讨pH值和盐浓度对金属螯合亲和层析(Immobilized metal ion affinity chromatography,IMAC)分离含His-Tag标签的人胰高血糖素样肽-1(Glucagon-like peptide-1,GLP-1)融合蛋白的影响,并确定最佳洗脱条件。方法在0.50mol/L盐浓度条件下,分别取pH6.0、7.0、7.8和9.04种缓冲液进行咪唑梯度洗脱;在合适的pH值条件下,分别取氯化钠浓度0.25、0.50和0.75mol/L3种缓冲液进行咪唑梯度洗脱。分析在不同pH值及盐浓度条件下洗脱融合蛋白所需要的咪唑浓度及回收率。结果在所考察的pH值范围内,洗脱融合蛋白所需的咪唑浓度随洗脱液pH值的升高而逐渐降低,当洗脱液pH值为7.8时,融合蛋白的分离效果最佳,大部分杂蛋白被0~40mmol/L咪唑洗脱液去除且不含融合蛋白,而绝大部分融合蛋白在咪唑浓度达80~200mmol/L时被洗出,总回收率达(83.7±1.0)%,且比例较高;在此pH值条件下,氯化钠浓度达0.75mol/L,才会影响融合蛋白的回收率,氯化钠浓度为0.25或0.50mol/L的洗脱液洗出融合蛋白的效果相近;在pH7.8,含0.25mol/L氯化钠的洗脱体系下,用50mmol/L咪唑溶液洗脱杂蛋白,200mmol/L咪唑溶液洗脱融合蛋白,融合蛋白的回收率和比例分别可达(85.2±2.0)%和(80.5±1.0)%。结论在所考察的pH值和盐浓度范围内,提高洗脱液pH值和盐浓度均可降低洗脱融合蛋白需要的咪唑量,但也会降低融合蛋白的回收率。  相似文献   

17.
Three porous ceramic composites were prepared from readily available raw materials (kaolin, bauxite, feldspar and kyanite). The porous ceramic formulations were sintered at different temperatures ranging from 1200 to 1400°C. The fired specimens were characterized by determining their porosity, bulk density, flexural strength, thermochemical stability, microstructure, water and mercury permeability. Apparent porosity and bulk density in the range 15.57 ± 1.56–42.73 ± 2.28?vol% and 2.23 ± 0.31–2.68 ± 0.41?g?cm?3 respectively were obtained after firing. The flexural strength was in the range of 32.31 ± 2.1–74.88 ± 2.57?MPa and the thermal expansion coefficient of 5–9 × 10?6 C?1. The values of water permeability were 745.4, 641.45 and 525.91?L/m2 h?kPa respectively for PK3, PK4 and PK5. It was found that at high temperature (1400?°C), kyanite particles enhanced the porosity and thermal stability by reducing glass formation and improving crystallization. The presence of the interconnected pores with size between 0.03 and 4.50?µm, the high total volume of pores together with the high flexural strength and thermal stability make the synthesized porous ceramics suitable for high-pressure filtering applications.  相似文献   

18.
The optimal extraction parameters of Mopan persimmon polysaccharide (MPP) were ultrasonic power 900 W, ultrasonic treatment time 3 min, and water addition 2000%. Four subfractions (MPP‐1, MPP‐2b, MPP‐3, and MPP‐4b) were separated by DEAE–52 cellulose anion‐exchange column chromatography and then Sephadex G‐200 gel column chromatography. The in vitro scavenging effects of MPP and MPP‐4b at a dosage of 10 g/L on hydroxyl radical were 94.15 ± 8.27% and 96.61 ± 8.06%, respectively. The 1,1‐diphenyl‐2‐picrylhydrazyl inhibition percentages of two polysaccharides fractions were 93.37 ± 7.66% and 70.79 ± 6.15%, respectively. The reducing power (absorbance at 700 nm) of MPP and MPP‐4b were 4.31 ± 0.26 and 5.09 ± 0.33, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

19.
采用交联聚丙烯酸钠(PAAS)为吸水材料,通过动态硫化法制备了聚氯乙烯(PVC)j氯化聚乙烯橡胶(cM)热塑性硫化胶(TPV),并对其力学性能、微观相态结构及吸水行为进行了研究。结果表明:在实验范围内,PVC/PAAS/CMTPV呈现出典型弹性体软而韧的应力应变行为;PAAS在基体中实现了均匀分散,且随着PAAS含量的增加,PVC/PAAS/CMTPV的力学性能呈下降趋势;PVC/PAAS/CMTPV的吸水性能随着PAAs的含量增加而显著提高,且在PAAS加入量为60phr时急剧增加;由于基体的屏蔽作用,PVC/PAAS/CMTPV没有出现明显的溶出现象。  相似文献   

20.
Air pollution has seriously threatened public health in developing countries. However, it is still a big challenge for fabricating a filter with high filtration efficiency, low air resistance, and long service life. Herein, we report a facile strategy to fabricate a multilayered nonwoven composite with a functionally gradient structure for air filtration by a combined method of needle-punch, melt blown, and corona charging techniques. Our integrated multilayer needle-punched/melt blown composite filter could achieve a high filtration efficiency up to 99.52 ± 0.01%, a low pressure drop of 136.87 ± 0.49 Pa, and a satisfied quality factor of 0.03898 ± 0.0001 Pa−1 for sodium chloride particles with an aerodynamic diameter of 0.26 μm at the airflow rate of 85 L min−1. More importantly, the resultant filter exhibited a large dust holding capacity of 23.5 ± 0.41 g m−2, which indicates a long service life. It is expected that our multilayer needle-punched/melt blown composite fabric may not only serve as a good candidate for air filtration, but also provide a new sight for designing the air filtration materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47827.  相似文献   

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