Preparation of Cellulose Acetate Butyrate Porous Micro/Nanofibrous Membranes and Their Properties

Cellulose acetate butyrate(CAB)is a cellulose ester that is commonly used in applications such as coatings and leather brighteners.However,its appearance in a fibrous form is rarely reported.CAB porous micro/nanofibrous membranes with a large number of nanopores on the fiber surface were successfully prepared by electrospinning with dichloromethane(DCM)/acetone(AC)as the mixed solvent.Apparent morphology,porosity,moisture permeability,air permeability,static water contact angles,and thermal conductivity of the fibrous membranes were investigated at different spinning voltages.The results showed that with the increase of the spinning voltage,the average fiber diameter of the CAB porous micro/nanofibrous membranes gradually decreased and the fiber diameter distribution was more uniform.When the spinning voltage reached 40 kV,the porosity reached 91.38%,the moisture permeability was up to 7430 g/(m^(2)·d),the air permeability was up to 36.289 mm/s,the static water contact angle was up to 145.0°,while the thermal conductivity of the fibrous membranes reached 0.030 W/(m·K).The material can be applied as thermal-insulation,waterproof and moisture-permeable membranes.

Effect of Soil Drought Stress on Leaf Water Status, Membrane Permeability and Enzymatic Antioxidant System of Maize

A simulation experiment on the responses of maize (Zea mays L.) from the third leaf stage to maturity for different soil water levels (well-watered, moderately stressed, and severely stressed) was conducted by controlling irrigation and using a mobile rain shelter in a neutral loam, meadow soil to determine the effects on leaf water status, membrane permeability and enzymatic antioxidant system for different growth stages. The results indicated that drought stress relied on drought intensity and duration, with more severe drought stress creating more serious effects on maize. Compared with well-watered conditions, during the silking and blister stages moderate stress did not significantly change the relative water content (RWC) and did change significantly the relative conductivity (RC) (P < 0.05) of the leaves; however, severe stress did significantly decrease (P < 0.01) the leaf RWC and increase (P < 0.01) membrane permeability (leaf relative conductivity). Furthermore, under severe drought stress antioxidant enzyme activities declined significantly (P < 0.01) in later stages, namely for superoxide dismutase (SOD) the tasseling and blister stages, for peroxidase (POD) the milk stage, and for catalase (CAT) during the tasseling, blister, and milk stages. Meanwhile, membrane lipid peroxidation (measured as malondialdehyde content) significantly increased (P < 0.01) in all stages.

Effects of exogenous Ca^(2+) on the membrane permeability, MDA and SH group content of Alexandrium sp. LC3 under surfactant stress

The effect of Ca 2+ on the removal of Alexandrium sp. LC3 under HDTMAB stress was investigated. The results showed that the toxic effect of HDTMAB on Alexandrium sp. LC3 was significantly reduced in the presence of Ca 2+, especially under 4 mmol/L of Ca 2+. To understand the underlying mechanism, the SH group and MDA content of the cell membrane and membrane permeability were measured. It was found that the SH content of cell member increased, the MDA content and membrane permeability decreased when Alexandrium sp. was treated with Ca 2+ and HDTMAB complex, compared with using HDTMAB only. The data suggested that Ca 2+ might promote HDTMAB stress resistance of Alexandrium sp. LC3 by reducing the permeability and increasing the stability of cell membrane.

A low-cost in-situ CO_(2) sensor based on a membrane and NDIR for long-term measurement in seawater

The multi-point simultaneous long-term measurement of CO_(2) concentration in seawater can provide more-valuable data for further understanding of the spatial and temporal distribution of CO_(2).Thus,the requirement for a low-cost sensor with high precision,low power consumption,and a small size is becoming urgent.In this work,an in-situ sensor for CO_(2) detection in seawater,based on a permeable membrane and non-dispersive infrared(NDIR)technology,is developed.The sensor has a small size(Ф66 mm×124 mm),light weight(0.7 kg in air),low power consumption(<0.9 W),low cost(<US$1000),and high-pressure tolerance(<200 m).After laboratory performance tests,the sensor was found to have a measurement range of(0–2000)×10^(-6),and the gas linear correlation R^(2) is 0.99,with a precision of about 0.98%at a sampling rate of 1 s.A comparison measurement was carried out with a commercial sensor in a pool for 7 days,and the results showed a consistent trend.Further,the newly developed sensor was deployed in Qingdao nearshore water for 35 days.The results proved that the sensor could measure the dynamic changes of CO_(2) concentration in seawater continuously,and had the potential to carry out long-term observations on an oceanic platform.It is hoped that the sensor could be applied to field ocean observations in near future.

Effect of NdCl_3 on the Injury of Membrane and ABA Content under Osmotic Stress

Wheat seedlings grown in 0. 67 MPa Polyethylene glycol(PEG) , the relative water content(RWC) of leaves declined, the malondialdehyde(MDA) content and the permeability of plasma-membrane increased. The activity of superoxide dismutase (SOD) decreased, but that of peroxidase (POD) increased. At 3 h and 15 h osmotic treatment the abscisic acid(ABA) content showed two peaks respectively. When 0. 67 MPa PEG contained 35 4mol/L NdCl3 the RWC was higher than that of the control, the permeability of the plasma membrane and the MDA content were decreased. The activity of SOD of POD all increased by adding NdCl3. The ABA content showed only one peak at 24 h osmotic treatment, and the value of that peak declined obviously when treated with NdCl3.

Preparation and characterization of a composite membrane based on the asphaltene component of coal

Asphaltene-ceramic composite membranes were fabricated from ceramic supports and an asphaltene component, which was obtained from the separation of coal to give a kind of new carbonaceous precursor material. Using SEM and thermogravimetric analysis to measure the microstructure and properties of the asphaltene component allowed the porosity, permeability, and retention ratios to be determined. The results show that the asphaltene component can be regarded as a good carbon membrane precursor material because of its high carbon content and strong bonding capacity. When ceramic supports are impregnated with asphaltene colloid the asphaltene easily combines with the support surface and forms a good carbonaceous film after carbonization. Little of the asphaltene component permeates into the internal pores of the ceramic support. Although the number of coats applied to the substrate had little affect on the porosity of the asphaltene-ceramic composite membranes the permeability varied depend- ing upon the number of times the substrate was treated. The way bubbles escape from the film, and the phenomenon of coalescence, as affected by different film thicknesses also seem closely related to the number of coats. A composite membrane carbonized at a final temperature of 600℃ is relatively dense and the permeability of Fe（OH）3 colloid through it is very low. A membrane fired at 800℃ is porous and its permeability and retention of Fe（OH）3 colloid are 88 L/（m2 h MPa） and 85.3%, respectively when the trans-membrane pressure is 0.22 MPa.

A novel approach to regulate cell membrane permeability for ATP and NADH formation in Saccharomyces cerevisiae induced by air cold plasma

Air cold plasma has been used as a novel method for enhancing microbial fermentation. The aim of this work was to explore the effect of plasma on membrane permeability and the formation of ATP and NADH in Saccharomyces cerevisiae, so as to provide valuable information for largescale application of plasma in the fermentation industry. Suspensions of S. cerevisiae cells were exposed to air cold plasma for 0, 1, 2, 3, 4 and 5 min, and then subjected to various analyses prior to fermentation （Oh） and at the 9 and 21 h stages of fermentation. Compared with nonexposed cells, cells exposed to plasma for 1 min exhibited a marked increase in cytoplasmic free Ca2＋ concentration as a result of the significant increase in membrane potential prior to fermentation. At the same time, the ATP level in the cell suspension decreased by about 40%, resulting in a reduction of about 60% in NADH prior to culturing. However, the levels of ATP and NADH in the culture at the 9 and 21 h fermentation stages were different from the level at 0 h. Taken together, the results indicated that exposure of S. cerevisiae to air cold plasma could increase its cytoplasmic free Ca2＋ concentration by improving the cell membrane potential, consequently leading to changes in ATP and NADH levels.

Effect of Lanthanum Chloride on Membrane Permeability of Corn Root Tissue

The effect of lanthanum ion on membrane permeability of corn root segment is studied.Results shows that treatment of the root segments with LaCl_3·7H_2O can decrease the ion leakage of the root tissue.The leakage decreases hy increasing the concentration of lanthanum,and the concentration has no further dependence on ion leakages above 25 μmol/L.After treating the root tissue for one hour with lanthanum ion,the amount of leak- age has linear dependence on time within the first 2 h and after two hours the leakage increases.The ion leakage of the tissue dependes on the time of lanthanum treatment.When the duration of treatment is prolonged,the leakage decreases rapidly and the leakage reaches a minimum at 30 minutes.Other rare earth elements can also decrease ion leakage.There is no significant difference in the ion leakage among these elements.

Enhancement of CREC sensitivity to fosfomycin by baicalein through increasing outer membrane permeability

Background:To confirm whether baicalein improves the sensitivity of carbapenem-resistant Escherichia coli(CREC)to fosfomycin by increasing the permeability of bacterial outer membrane in vitro experiments.Methods:The clinically isolated CREC strains were amplified and then divided into three groups including baicalein monotherapy groups,fosfomycin monotherapy groups,and baicalein plus fosfomycin groups,and their minimum inhibitory concentrations(MICs)measurement and interpretation were performed according to CLSI interpretive criteria.To determine bacterial permeability after contact with baicalein,CREC were incubated with fluorescein isothiocyanate(FITC)after pretreatment with blank control without baicalein,with 0.25 MIC of baicalein,and with 0.125 MIC of baicalein,followed by observation of the intrabacterial fluorescence intensity of FITC.In addition,CREC were pretreated with 0.125 MIC of baicalein and with blank control without baicalein followed by measurement of alkaline phosphatase(AKP)leak to determine the change of bacterial permeability.Results:The MIC range in baicalein monotherapy groups was from 128 mg/L to 256 mg/L,and the MIC range in fosfomycin monotherapy groups was from 16 mg/L to 1,024 mg/L,but the MIC range in both combination therapy groups was reduced to 4 mg/L to 64 mg/L.The combination use reduced the MIC of each therapy by 75%-96.88%in all strains,and the fractional inhibitory concentration index(FICI)values less than or equal to 0.5.In the permeability assay,no permeabilization of FITC was observed in the blank groups without baicalein,but the intrabacterial FITC aggregation was observed in the groups of pretreatment with 0.25 MIC of baicalein or 0.25 MIC of baicalein.In the AKP leak assay,the AKP leak was more severe at the groups of coincubation with 0.25 MIC of baicalein than those blank groups without baicalein within the first 6 hours.Conclusion:Our study suggests that baicalein may synergistically enhance the antibacterial effect of fosfomycin by increasing the permeability of CREC outer membrane.

The role of extracellular calcium in the effect of a snake venom Lys49-phospholipase A_(2) on water transport across epithelial membranes

ACLMT is a Lys49-phospholipase A2 myotoxin isolated from the venom of the Agkistrodon contortrix laticinctus snake. This study investigated the mechanisms involved in effect of ACLMT on membrane water permeability by examining the role of extracellular calcium and strontium in this effect. Water flow across the membrane was gravimetrically measured in bladder sac preparations. The decrease in extracellular calcium promoted a higher response of epithelium to ACLMT, suggesting that the extracellular calcium protects the membrane from the action of the toxin. No alteration in the effect of the toxin on water transport was observed when calcium was replaced by strontium, indicating that this effect is independent of its enzymatic activity. These findings may bring an important contribution towards the comprehension of the mechanisms involved in the effect of Lys49-phospholipase A2 myotoxins on water permeability of epithelial membranes, with implications for the understanding of renal toxicity.

Functions and mechanisms of cytosolic phospholipase A_(2)in central nervous system trauma

Central nervous system(CNS)trauma,including traumatic brain injury and spinal cord injury,has a high rate of disability and mortality,and effective treatment is currently lacking.Previous studies have revealed that neural inflammation plays a vital role in CNS trauma.As the initial enzyme in neuroinflammation,cytosolic phospholipase A_(2)(cPLA2)can hydrolyze membranous phosphatides at the sn-2 position in a preferential way to release lysophospholipids andω3-polyunsaturated fatty acid dominated by arachidonic acid,thereby inducing secondary injuries.Although there is substantial fresh knowledge pertaining to cPLA2,in-depth comprehension of how cPLA2 participates in CNS trauma and the potential methods to amelio rate the clinical res ults after CNS trauma are still insufficient.The present review summarizes the latest understanding of how cPLA2 participates in CNS trauma,highlighting novel findings pertaining to how cPLA2 activation initiates the potential mechanisms specifically,neuroinflammation,lysosome membrane functions,and autophagy activity,that damage the CNS after trauma.Moreover,we focused on testing a variety of drugs capable of inhibiting cPLA2 or the upstream pathway,and we explored how those agents might be utilized as treatments to improve the results following CNS trauma.This review aimed to effectively understand the mechanism of cPLA2 activation and its role in the pathophysiological processes of CNS trauma and provide clarification and a new referential framework for future research.

Characterization of Energy_Transduction in Thermal Pretreated Chloroplast from Spinach

Characterization of energy-transduction on die chloroplast thylakoid membranes from spinach (Spinacia oleracca L.) after thermal pretreatment was investigated. The related reactions of energy-transduction in chloroplasts were seriously affected by thermal pretreatment. The results were obtained as following: (1) The rate of cyclic photophosphorylation declined when the pretreatment temperature increased in the range of 25 to 45 degreesC. (2) The thermal pretreatment led to a decrease of the activity of thylakoid membrane-bounded ATPase. (3) Proton uptake of chloroplasts acid the fluorescence quenching of 9-aminoacridine (9-AA) in thylakoid membrane decreased after the thermal pretreatment, but addition of dicyclohexylcarbodiimide (DCCD) could partially restore the fluorescence quenching of 9-AA. (4) Both the rates of fast phase in electrochroism absorption change at 515 nm and the millisecond delayed light emission (ms-DLE) of chloroplast showed a progressive decrease upon raising the temperature of pretreatment. (5) Immunbloting analysis showed that the thermal pretreatment caused the changes of protein content and the electrophoresis mobility of thylakoid membrane-bound ATPase and its alpha -subunit. (6) If the temperature of pretreatment were higher than 33 degreesC, oxygen uptake of PS I -mediated in the samples was rapidly inhibited, but addition of sinapine into the reaction medium could partially restore the ability of oxygen uptake in the samples. These results are briefly discussed in relation to the change of permeability of thylakoid membranes, the dissociation of coupling factor complex as well as accumulation of the radicals in the thylakoid membranes after thermal pretreatment.

Effect of Rare Earths on Plants under Supplementary Ultraviolet-B Radiation: Ⅱ. Effect of Cerium on Antioxidant Defense System in Rape Seedlings under Supplementary Ultraviolet-B Radiation

Effects of cerium （Ce^3＋ ） on membranous protective enzymes in rape seedlings exposed to two levels of enhanced uhraviolet-B radiation （UV-B, 280 - 320 nm） were studied by hydroponics in the laboratory. The results show that the chlorophyll content decreases and membrane permeability increases in the leaves under UV-B irradiation with an intensity of 0.15 and 0.35 W·m^-2. The activities of SOD, CAT and POD are first increased and then decreased in leaves exposed to a low level of UV-B radiation. POD activity in leaves exposed to a high level of UV-B radiation is enhanced constantly. The sensitivities of these enzymes to UV-B radiation are SOD 〉 CAT 〉 POD. The injury by UV-B radiation on the functions of protective enzymes is lightened, their ability to scavenge radicals is improved, and the membrane permeability is maintained by Ce. Furthermore, the protective effect of cerium is more obvious in plants exposed to low levels of UV-B radiation than to high levels of it. Accordingly, all results prove that the protective effect of Ce on plants under UV-B radiation is realized through the protective system of plants.

Changes induced by osmotic stress in the morphology, biochemistry, physiology, anatomy and stomatal parameters of almond species(Prunus L. spp.) grown in vitro

We investigated the influence of different levels of osmotic stress on growth and development in selected wild almond species （eight Prunus spp.） grown in vitro. The study, while endorsing the efficacy of in vitro screening of auxiliary buds of wild almond for osmotic stress tolerance, showed species variability in its response to osmotic stress. Osmotic stress reduced growth and development of all the species. How-ever, the putative tolerant Prunus spp. showed better performance than the putative susceptible genotypes. On average there was an 80% de-crease in shoot dry weight at -1.2 MPa. Reduction in shoot weight was more common in osmotic stress-susceptible species in the section labeled‘Euamygdalus’. The tolerant Prunus species produced smaller changes in biochemical responses than the sensitive cultivars for malondialdehyde content, catalase activity, relative permeability of protoplast membranes, and net photosynthetic rate. The tolerant species maintained cell integrity better than drought sensitive species. Wild almond species in the section labeled ‘Spartioides’ （Prunus arabica （Olivier） Neikle, Prunus glauca＆amp;nbsp;（Browicz） A.E. Murray, Prunus scoparia Spach） and ‘Lycioides’ （Pru-nus lycioides Spach, Prunus reuteri Bossi. et Bushe） were best adapted to osmotic stress. Increase in chlorophyll concentration and leaf thickness under high osmotic stress can be considered as preliminary selection parameters for osmotic stress tolerance in Prunus spp. The study con-firmed the efficacy of the in vitro method for screening of large number of genotypes for osmotic stress tolerance in wild almond species.

Seed priming improves early seedling vigor, growth and productivity of spring maize

Potential of seed priming treatments in improving the performance of early planted maize was evaluated against timely planting. Seeds of maize hybrid FH-810 were soaked in water (hydropriming), CaCl2 (2.2%, osmopriming), moringa leaf extracts (MLE 3.3%, osmopriming) and salicylic acid (SA, 50 mg L–1, hormonal priming) each for 18 h. Untreated and hydroprimed seeds were taken as control. Seeds primed with SA took less time in emergence and had high vigor in early planted maize. Amongst treatments, hormonal priming, reduced the electrical conductivity, increased the leaf relative and chlorophyl contents fol owed by osmopriming with CaCl2 at seedling stage. Likewise, plant height, grain rows and 1 000-grain weight, grain and biological yield and harvest index were also improved by seed priming;however hormonal priming and osmopriming with MLE were more effective in this regard. Improved yield performance by hormonal priming or osmopriming with MLE in early planting primarily owed to increased leaf area index, crop growth and net assimilation rates, and maintenance of green leaf area at maturity. In conclusion, osmopriming with MLE and hormonal priming with SA were the most economical treatments in improving productivity of early planted spring maize through stimulation of early seedling growth at low temperature.

Electron paramagnetic resonance study of amphiphiles partitioning behavior in desiccation-tolerant moss during dehydration

Desiccation tolerance is a crucial characteristic for desert moss surviving in arid regions. Desiccation procedure always induces amphiphiles transferring from the polar cytoplasm into lipid bodies. The behavior of amphiphiles transferring can contribute to the enhancement of desiccation tolerance and the reduction of plasma membrane integrity simultaneously. The effects of amphiphiles partitioning into the lipid phase during water loss has been studied for pollen and seeds using electron paramagnetic resonance （EPR） spectroscopy. However, desiccation-tolerant high plants occur among mosses, several angiosperms and higher plants seeds or pollens. They have different strategies for survival in dehydration and rehydration. A desiccation-tolerant moss Tortula desertorurn was used to investigate the behaviors of amphiphilic molecules during drying by spin label technology. There are small amount of amphiphilic probes partitioning into membrane during moss leaves dehydration, comparing with that in higher plants. Cytoplasm viscosity changed from 1.14 into glass state only dehydration less than 60 min. Moss leaves lost plasma membrane integrity slightly,from 0.115 to 0.237, occurred simultaneously with amphiphiles partition. The results showed the more advantages of mosses than higher plants in adapting fast dehydration. We propose that EPR spin label is feasible for studying the amphiphiles partitioning mechanisms in membrane protection and damage for desiccation-tolerant mosses.

Characteristics of water relations in seedling of Machilus yunnanensis and Cinnamomum camphora under soil drought condition

The soil drought stress experiment in different durations (no watering within 3d, 6d, 9d, 11d individually) was conducted to study the drought-resistant capacity of one-year-old seedlings for the native tree species (Machilus yunnanensis) in Yunnan Province and the introduced tree species (Cinnamomum camphora). The leaf water potential, chlorophyll content, proline content and plasma membrane permeability for two species seedlings were measured in different soil drought conditions. The results showed that, on the 9th day of drought stress, the leaf water potential of two species decreased obviously, whereas the free proline content and plasma membrane permeability increased sharply. On the 11th day, the leaf water potential of C. camphora seedlings was lower than that of M. yunnanensis seedlings; the plasma membrane permeability in C. camphora seedling leaves increased much more than that in M. yunnanensis seedling leaves, which showed that the injury to the former by soil drought stress was more severe than that to the latter. The free proline content in M. yunnanensis seedling leaves continued to increase on the 11th day, but that in the C. camphora seedling leaves started to drop obviously, indicating that the reduction of osmotic regulation substance in C. camphora seedling leaves after the 11th day was unable to maintain the osmotic balance between the plasma system and its surroundings and the water loss occurred inevitably. Comprehensively, M. yunnanensis seedlings enhanced the drought-resistance in the course of soil drought stress by maintaining higher leaf water potential and by increasing osmotic regulation substance to promote cell plasma concentration and maintain membrane structure integrity so as to reduce water loss. The subordination function index evaluated with fuzzy mathematic theory also showed that the drought-resistant capacity of M. yunnanensis seedlings was stronger than that of C. camphora seedlings.

Promotion of hexadecyltrimethyleamine bromide to the damage of Alexandrium sp.LC3 by cupric glutamate

The effect of hexadecyltrimethyleamine bromide （HDTMAB） on the removal of A lexandrium sp. LC3 under cupric glutamate stress was investigated. Toxic effect of cupric glutamate on A lexandrium sp. LC3 was significantly promoted in the presence of HDTMAB, especially at 3.0 cmc of HDTMAB. It was found that the sulfhydryl group content of the cell decreased, while the malonaldehyde content and membrane permeability increased when A lexandrium sp. LC3 was treated with HDTMAB and cupric glutamate complex, compared with cupric glutamate alone. The data suggest that HDTMAB might stimulate the damage of A lexandrium sp. LC3 by enhancing the membrane permeability.

Effect of Drought Stress on Growth and Water Physiological Characteris­tics of Poa sibirica

In order to develop the resources of native turfgrass,the morphological traits and drought resistance of native Siberian bluegrass(Poa sibirica,abbreviated as PS)was evaluated using the introduced Kentucky bluegrass'Midnight'(Poa pratensis,abbreviated as PP)as a control.Two water schemes were imposed to plants in this pot culture study in greenhouse.One was with drought stress persistent limiting water supply for 20 days,the other was re-hydrated until 14 days after drought.The leaf shape,turf color,water status and cell plasma membrane permeability were evaluated.Similar changing trends with these parameters were shown for both species,and there were not significant differences with most evaluations during drought and re-water periods.The values leaf width and length of PS were higher while leaf color intensity was slightly lower than that of PP,but the greenness of PS leaf was still visually acceptable.There were not significant differences with cell membrane stability between the two species.In comparison,the native wild species PS possessed the potential for to be domesticated into a new cultivar for turf industry.

Disruption of colonic barrier function and induction of mediator release by strains of Campylobacter jejuni that invade epithelial cells

AIM: To study the mechanisms by which Campylobacter jejuni (C. jejuni) causes inflammation and diarrhea. In particular, direct interactions with intestinal epithelial cells and effects on barrier function are poorly under- stood. METHODS: To model the initial pathogenic effects of C. jejuni on intestinal epithelium, polarized human colonic HCA-7 monolayers were grown on permeabilized filters and infected apically with clinical isolates of C. jejuni. Integrity of the monolayer was monitored by changes in monolayer resistance, release of lactate dehydrogenase, mannitol fluxes and electron microscopy. Invasion of HCA-7 cells was assessed by a modified gentamicin protection assay, translocation by counting colony forming units in the basal chamber, stimulation of mediator release by immunoassays and secretory responses in monolayers stimulated by bradykinin in an Ussing chamber. RESULTS: All strains translocated across monolayers but only a minority invaded HCA-7 cells. Strains that invaded HCA-7 cells destroyed monolayer resistance over 6 h, accompanied by increased release of lactate dehydrogenase, a four-fold increase in permeability to [3H] mannitol, and ultrastructural disruption of tight junctions, with rounding and lifting of cells off the filter membrane. Synthesis of interleukin (IL)-8 and prostaglandin E2 was increased with strains that invaded the monolayer but not with those that did not. CONCLUSION: These data demonstrate two distinct effects of C. jejuni on colonic epithelial cells and provide an informative model for further investigation of initial host cell responses to C. jejuni.