Effects of Sn residue on the high temperature stability of the H_2-permeable palladium membranes prepared by electroless plating on Al_2O_3 substrate after SnCl_2–PdCl_2 process: A case study

The stability of composite palladium membranes is of key importance for their application in hydrogen energy systems. Most of these membranes are prepared by electroless plating, and beforehand the substrate surface is activated by a SnCl_2–PdCl_2 process, but this process leads to a residue of Sn, which has been reported to be harmful to the membrane stability. In this work, the Pd/Al_2O_3 membranes were prepared by electroless plating after the SnCl_2–PdCl_2 process. The amount of Sn residue was adjusted by the SnCl_2 concentration, activation times and additional Sn(OH)_2coating. The surface morphology, cross-sectional structure and elemental composition were analyzed by scanning electron microscopy(SEM), metallography and energy dispersive spectroscopy(EDS), respectively. Hydrogen permeation stability of the prepared palladium membranes were tested at450–600 °C for 400 h. It was found that the higher SnCl_2 concentration and activation times enlarged the Sn residue amount and led to a lower initial selectivity but a better membrane stability. Moreover, the additional Sn(OH)_2coating on the Al_2O_3 substrate surface also greatly improved the membrane selectivity and stability.Therefore, it can be concluded that the Sn residue from the SnCl_2–PdCl_2 process cannot be a main factor for the stability of the composite palladium membranes at high temperatures.

Morphological stability analysis of vesicles with mechanical-electrical coupling effects

Using a recently established liquid crystal model for vesicles, we present a theoretical method to analyze the morphological stability of liquid crystal vesicles in an electric field. The coupled mechanical-electrical effects associated with elastic bending, osmotic pressure, surface tension, Max- well pressure, as well as flexoelectric and dielectric proper- ties of the membrane are taken into account. The first and second variations of the free energy are derived in a com- pact form by virtue of the surface variational principle. The former leads to the shape equation of a vesicle embedded in an electric field, and the latter allows us to examine the stabil- ity of a given vesicle morphology. As an illustrative exam- ple, we analyze the stability of a spherical vesicle under a uniform electric field. This study is helpful for understanding and revealing the morphological evolution mechanisms of vesicles in electric fields and some associated phenomena of cells.

Melittin enhanced intracellular trehalose with synergistic membrane stabilization of macromolecular protectants for cell cryopreservation

Cryopreservation plays an essential role in biobanking and cell therapy,but the physiological toxicity of traditional cryoprotectants such as glycerol and dimethyl sulfoxide(DMSO)has raised safety issues for biomedical applications.Trehalose,a nonreducing disaccharide that accumulates in desiccation-or cold-tolerant organisms,has been considered as a biocompatible cryoprotectant.Herein,a naturally occurring membrane-active cationic peptide,melittin,was utilized to facilitate membraneimpermeable trehalose entry into cells for effective cell cryopreservation.Poly(ethylene glycol)and poly(vinyl pyrrolidone)were applied as macromolecular protectants to improve the stabilization of cell membranes.Upon the optimal protocol,the postthaw recovery of human red blood cells in freezing bags at a hematocrit of~50%could achieve 82.9%with favorable cell morphologies and physiological functions.Furthermore,the cryosurvival of L929 fibroblasts reached 84.3%compared to the conventional method using 10%(v/v)DMSO.In short,this work by using trehalose and melittin provides a biocompatible solvent-free approach for long-term cryostorage of cells.

Long Term Salinity Stress Reveals Variety Specific Differences in Root Oxidative Stress Response

Salinity stress induces oxidative stress caused by reactive oxygen species （ROS）： superoxide radicals, hydrogen peroxide （H2O2） and hydroxyl radicals. Activities of both enzymatic and non-enzymatic components of the antioxidant system and related growth parameters were studied in the roots of the salt tolerant rice variety FL478 and the sensitive variety IR29 in response to long term stress （12 d）induced by 50 mmol/L NaCI. The comparative study showed that FL478 maintained higher relative growth rate and lower Na＋/K＋ in the roots than IR29 due to a higher membrane stability index that effectively exclude Na＋. Lower TBARS （thiobarbituric acid reactive substance） content in FL478 roots indicated that its membrane was relatively unaffected by ROS despite high H2O2 content recorded under the salinity stress. Relatively higher superoxide dismutase activity along with a parallel increase in transcript level of superoxide dismutase （Os07g46990） in FL478 indicated that this protein might make a vital contribution to salt stress tolerance. Although the content of ascorbic acid remained unchanged in FL478, the activity of ascorbic peroxidases （APOXs） was reduced comparably in the both varieties. Transcriptomic data showed that a larger number of peroxidase genes were upregulated in FL478 compared to IR29 and several of which might provide engineering targets to improve rice salt tolerance.

Temporal Dynamics of Antioxidant Defence System in Relation to Polyamine Catabolism in Rice under Direct-Seeded and Transplanted Conditions

Six rice cultivars viz. PR120, PR116, Feng Ai Zan, PR115, PAU201 and Punjab Mehak 1 under the direct-seeded and transplanted conditions were used to investigate the involvement of antioxidative defence system in relation to polyamine catabolism in temporal regulation of developing grains. Activities of ascorbate peroxidase （APx）, guaiacol peroxidase （GPx）, catalase （CAT）, superoxide dismutase （SOD）, polyamine oxidases （PAO） and contents of ascorbate, a-tocopherol, proline and polyamines increased gradually until mid-milky stage and then declined towards maturity stage under both planting conditions. The transplanted condition led to higher activities of antioxidative enzymes （APx, GPx and CAT） and contents of ascorbate, a-tocopherol and proline whereas the direct-seeded condition had elevated levels of PAO and SOD activities and contents of polyamines, lipid peroxide and hydrogen peroxide. Cultivars Feng Ai Zan and PR120 exhibited superior tolerance over other cultivars by accumulating higher contents of ascorbate, a-tocopherol and proline with increasing level of PAO and SOD activities under the direct-seeded condition. However, under the transplanted condition PR116 and PAU201 showed higher activities of antioxidative enzymes with decreasing content of lipid peroxide. Therefore, we concluded that under the direct-seeded condition, enhancements of polyamines content and PAO activity enabled rice cultivars more tolerant to oxidative stress, while under the transplanted condition, antioxidative defence with decreasing of lipid peroxide content was closely associated with the protection of grains by maintaining membrane integrity during rice grain filling. The results indicated that temporal dynamics of H2O2 metabolic machinery was strongly up-regulated especially at the mid-milky stage.

Benzimidazolium Functionalized Polysulfone-based Anion Exchange Membranes with Improved Alkaline Stability

The stability of anion exchange membranes（AEMs） is an important feature of alkaline exchange membrane fuel cells（AEMFCs）, which has been extensively studied. However it remains a real challenge due to the harsh working condition. Herein, we developed a novel type of polysulfone-based AEMs with three modified 1,2-dimethylbenzimidazoliums containing different substitutes at C4-and C7-position. The results showed that the introduction of the substitutes could obviously improve the dimensional and alkaline stabilities of the corresponding membranes. The swelling ratios of resultant AEMs were all lower than 10% after water immersion. The membrane with 4,7-dimethoxy-1,2-dimethylbenzimidazolium group exhibited the highest alkaline stability. Only 9.2% loss of hydroxide conductivity was observed after treating the membrane in 1 mol·L^（-1） KOH solution at 80 °C for 336 h. Furthermore, the density functional theory（DFT） study on the three functional group models showed that the substitutes at C4-and C7-position affected the lowest unoccupied molecular orbital（LUMO） energies of the different 1,2-dimethylbenzimidazolium groups.

Fluorite Ce_(0.8)Sm_(0.2)O_(2-δ) porous layer coating to enhance the oxygen permeation behavior of a BaCo_(0.7)Fe_(0.2)Nb_(0.1)O_(3-δ) mixed conductor

Fluorite Ce0.8Sm0.2O2-δ（SDC） nanopowder with a crystallite size of 15 nm was synthesized by a co-precipitation method. An SDC porous layer was coated onto a BaCo0.7Fe0.2Nb0.1O3-δ（BCFN） mixed conductor to improve its oxygen transport behavior. The results show that the SDC-coated BCFN membrane exhibits a remarkably higher oxygen permeation flux（JO2） than the uncoated BCFN in the partial oxidation of coke oven gas（COG）. The maximum JO2 value of the SDC-coated BCFN is 18.28 mL ·min^-1·cm^-2 under a COG/air flux of 177 mL ·min^-1/353 mL ·min^-1 at 875℃ when the thickness of the BCFN membrane is 1 mm; this JO2 value is 23% higher than that of the uncoated BCFN membrane. This enhancement is likely because of the higher oxygen ionic conductivity of SDC, which supplies oxygen vacancies and accelerates oxygen exchange on the membrane/coating layer/gas three-phase boundary.

Supplements of an aqueous combination of Justicia adhatoda and Ocimum tenuiflorum boost antioxidative effects and impede hyperlipidemia

Background: Justicia adhatoda and Ocimum tenuiflorum, locally known as bashok and tulsi, are two ethnomedicinally important herbs that have been using as dietary supplements for several therapeutic applications. This study evaluated the combined effect of both the herbs as an antioxidative and antihyperlipidemic agent.Methods: Antihyperlipidemic effect was assessed in a high-fat diet-induced hyperlipidemic model in Wistar albino rats. The rats were treated orally with extracts of bashok(J adhatoda, 200 mg/kg bw), tulshi(O tenuiflorum, 200 mg/kg bw), and a combination of bashok and tulshi(50:50), as well as with a reference drug, atorvastatin(10 mg/kg/day), with or without high-fat diet for 14 days. The antioxidative effect was studied using established in vitro models. The studies were supported by experimentally testing the effects of the extracts on membrane stabilization and inhibition of protein denaturation.Results: The results showed that the serum lipid profile was significantly decreased in the different treatment groups, with bashok having the greatest effect. Body weights, total serum protein, LDH, and relative liver and adipose tissue weights were markedly restored towards baseline values, the lowest atherogenic index being achieved with the combined extract. The combination treatment significantly enhanced total phenolic content and antioxidative capacity and greatly potentiated membrane stabilization, but inhibition of protein denaturation was not significantly affected.Conclusion: The data demonstrate that a combination of Justicia adhatoda and Ocimum tenuiflorum could be developed as a food supplement with antioxidative and antihyperlipidemic benefits.

Anti-inflammatory and membrane stabilizing properties of methyl jasmonate in rats

The present investigation was carried out to evaluate anti-inflammatory and membrane stabilizing properties of methyl jasmonate(MJ) in experimental rat models of acute and chronic inflammation.The effects of MJ on acute inflammation were assessed using carrageenan-induced rat's paw edema model.The granuloma air pouch model was employed to evaluate the effects of MJ on chronic inflammation produced by carrageenan in rats.The number of white blood cells(WBC) in pouch exudates was estimated using light microscopy.The levels of biomarkers of oxidative stress,such as malondialdehyde(MDA),glutathione(GSH) and activity of antioxidant enzymes in the exudates,were determined using spectrophotometry.The membrane stabilizing property of MJ was assessed based on inhibition of hemolysis of rat red blood cells(RBC) exposed to hypotonic medium.Our results indicated that MJ(25-100 mg·kg-1,i.p.) produced significant anti-inflammatory activity in carrageenan-induced paw edema in rats(P < 0.05).MJ reduced the volume of pouch exudates and the number of WBC in carrageenan-induced granulomatous inflammation.It also exhibited potent antioxidant and membrane stabilizing activities.In conclusion,these findings suggest the therapeutic potentials of methyl jasmonate in disease conditions associated with inflammation and its anti-inflammatory activity may be related to its antioxidant and membrane stabilizing activities.

Impact of blanching pretreatment on the drying rate and energy consumption during far-infrared drying of Paprika(Capsicum annuum L.)

We incorporated a superheated steam blanching pretreatment step into a paprika drying process and compared the far-infrared(FIR)drying rates,hardness of the sample surfaces,cell membrane stabilities,and energy consumption of blanched and non-blanched paprika.The average drying rate of blanched paprika samples during FIR drying was higher than that of non-blanched samples.The hardness and cell membrane stability of dried blanched samples were lower than those of non-blanched samples.We estimated that the softening of the sample surfaces and injury to the cell membranes caused the drying rate to increase.The total energy consumption of the FIR drying of paprika was reduced by approximately 30%by introducing the blanching pretreatment.These findings contribute to the development of environmentally friendly FIR drying techniques for paprika.

Effect of salinity changes on haemocyte of pearl oyster Pinctada martensii

Objective:To evaluate the impact of salinity changes in the rearing environment on the haemocyte activities of pearl oyster Pinctada martensii(P.martensii).Methods:Three salinity treatments including 12‰,22‰,and 32‰were tested.Haemocyte mortality rate and neutral red retention(NRR)assay were used to investigate the impact of rearing salinity on the haemocyte activities of pearl oyster.Results:Results from the present study indicated that salinity significantly affected the haemocyte mortality rate of P.martensii.The highest haemocytes mortality rate was observed in the 12‰treatment,and the lowest mortality rate was observed in the 32‰treatment.NRR time was also significantly affected by the salinity.The highest NRR time was observed in the 32‰treatment,and the lowest NRR time was observed in the 12‰treatment.Conclusions:Results from the present study indicated that salinity<22‰had significant impact on the haemocyte mortality rate and NRR time.Reducing the environmental salinity will pose an additional stress and may also reduce the defense capacities of P.martensii and make them more susceptible to parasites and bacteria.

Biological investigations of medicinal plants of Heliotropium indicum indigenous to Bangladesh

Objective:To investigate the clot lysis,antimicrobic and membrane stabilizing potentials of ethanolic extractives of the leaves of Heliotropium indicum(H.indicum).Methods:Crude ethanolic extracts of H.indicum leaves were partitioned successively using solvents of different polarity and subjected to determine qualitatively and quantitatively for the presence of different bioactive constitutes and fractions which were assessed for their possible clot lysis,antimicrobic,and membrane stabilizing activities as compared with the known drugs.Results:For the thrombolytic activity,the petroleum ether soluble fraction showed the highest percent of clot lysis(35.4%)among all fractions,while streptokinase and water resulted in 65.15%and 3.77%clot lysis,respectively.With respect to the membrane stabilizing activity,carbon tetrachloride soluble fraction of H.indicum profoundly interdicted the hemolysis of erythrocytes brought about by osmotic induction(39.24%)or by heat(40.20%).The other fractions exhibited less significant membrane stabilizing effect.By contrast,acetylsalicylic acid resulted in 72.25%±0.30%inhibition of osmotically induced hemolysis and showed a lower level of protection of heat induced hemolysis(42.56%).Crude ethanolic extracts were moderately sensitive against known pathogenic microbes.Since pharmacological activities of H.indicum are due to the presence of bioactive compounds,we detected and quantified the presence of significant levels of flavonoid and tannin substances.Conclusions:The outcomes of this research show that the leaves of H.indicum have the potential to be used as a remedy for thrombosis,inflammatory diseases and against few important bacterial pathogens.