Nanovesicles Based on Mixtures of a Biantennary Glycolipid with Ionic Co‐Surfactants

A biantennary surfactant based on a synthetic C₁₆‐maltoside was chosen to prepare vesicles for a potential vesicular drug delivery system. The synthesis comprised of three stages: Initial synthesis of β‐d ‐maltose octaacetate was followed by glycosidation of 2‐hexyl‐decanol and final glycolipid deacetylation. Both α‐ and β‐anomers were prepared and their anomeric purity was evaluated by ¹H NMR. Owing to the low water solubility of the glycolipid, addition of ionic co‐surfactants was believed to promote the surfactant distribution, thus leading to smaller and more uniform vesicles. The assembly behavior of the surfactant systems was studied by contact penetration under an optical polarizing microscope, while interfacial properties were determined by surface tension measurements. Vesicles were prepared by injection of an ethanolic solution into bulk water and investigated by dynamic light scattering and field emission scanning electron microscopy. Contact of the surfactant mixtures with water indicated a high tendency to exhibit the lamellar phase and confirmed the expected low molecular solubility. These findings suggest a potential of the surfactant to form stable vesicles. Injection of an ethanolic surfactant solution into bulk water gave sub‐micrometer sized vesicles with a narrow size distribution. Application of ionic co‐surfactants reduced the vesicle size. In particular ～20 % of anionic SDS proved highly effective, lowering the vesicle size by nearly one decade, thus accessing nano‐sized vesicles. Encapsulation of a water‐soluble drug was achieved in a 76 ± 10 % efficiency.     

Enhancement of stack ventilation in hot and humid climate using a combination of roof solar collector and vertical stack

In the hot and humid climate, stack ventilation is inefficient due to small temperature difference between the inside and outside of naturally ventilated buildings. Hence, solar induced ventilation is a feasible alternative in enhancing the stack ventilation. This paper aims to investigate the effectiveness of a proposed solar induced ventilation strategy, which combines a roof solar collector and a vertical stack, in enhancing the stack ventilation performance in the hot and humid climate. The methodology selected for the investigation is physical experimental modelling which was carried out in the actual environment. The results are presented and discussed in terms of two performance variables: air temperature and air velocity. The findings indicate that the proposed strategy is able to enhance the stack ventilation, both in semi-clear sky and overcast sky conditions. The highest air temperature difference between the air inside the stack and the ambient air (T_i−T_o) is achieved in the semi-clear sky condition, which is about 9.9 °C (45.8 °C–35.9 °C). Meanwhile, in the overcast sky condition, the highest air temperature difference (T_i−T_o) is 6.2 °C (39.3 °C–33.1 °C). The experimental results also indicate good agreement with the theoretical results for the glass temperature, the air temperature in the roof solar collector’s channel and the absorber temperature. The findings also show that wind has significant effect to the induced air velocity by the proposed strategy.     

转速对6061-T6铝合金搅拌摩擦搭接焊接头力学性能的影响(英文)

采用场发射扫描电子显微镜(FE-SEM),研究转速对厚度为5 mm的6061-T6铝合金搅拌摩擦搭接焊接头的宏观和微观组织、硬度、搭接头剪切性能和失效模式的影响。结果表明:在最低的转速度下,上模板和下模板具有十分相似的硬度分布。采用EDX分析发现,焊核区的断裂面中含有Fe的化合物。     

Preparation of cupric palmitate membrane,its characterization and evaluation of thermodynamically effective fixed charge density

Membrane potentials have been measured across, parchment-supported cupric palmitate membrane separating various 1∶1 electrolytes at concentrations C₁ and C₂ such that C₂=10 C₁. Membrane potential data have been used to calculate transference number of ions, permselectivity and also to derive the thermodynamically effective fixed charge density which is an important characteristic governing the membrane phenomena, by utilizing the generally accepted and most widely used theory of Teorell-Meyer and Sievers as well as the recent theories for membrane potential of Kobatake et al. and Nagasawa et al. based on the principles of nonequilibrium thermodynamics. The values of charge densities derived from different theories were almost the same, confirming thereby the validity of the recently developed theories of membrane potential.     

Matrix-assisted laser desorption/ionization mass spectrometry of proteins extracted directly from sodium dodecyl sulphate-polyacrylamide gels

A new strategy for the characterization of Coomassie Brilliant Blue stained SDS-PAGE separated proteins by UV-MALDI-MS is reported. The proteins are extracted directly from the polyacrylamide gel by treatment with an organic solvent mixture consisting of formic acid, acetonitrile, isopropanol and water in an ultrasonic bath. A fraction of the supernatant is then mixed directly with the matrix solution and measured by MALDI-MS. High quality spectra could be obtained from gels which were loaded with 6 pmol of myoglobin. Compared to other methods based on electroblotting or electroelution this method is much simpler and less time consuming. The sensitivity is higher than or comparable to the Coomassie Blue staining procedure for proteins up to about 25 kDa. Another advantage is that mass shifts due to charging effects of the membranes, which are common if membranes are mounted directly on the sample target, can be avoided. However, all proteins studied showed slightly higher masses than expected which reduces mass accuracy to 0.2-0.3%. This is presumably partly due to formylation of serine or threonine residues during incubation in formic acid. Gel electrophoresis induced modifications can contribute as well. The possibility of further characterizing the remaining part of the supernatant after extraction by means of proteolytic digestion is also demonstrated. The knowledge of both molecular weight of the whole protein and of the proteolytic fragments increases specificity for protein identification by searching in sequence databases.     

Computer-controlled microcirculatory support system for endothelial cell culture and shearing

Endothelial cells (ECs) lining the inner lumen of blood vessels are continuously subjected to hemodynamic shear stress, which is known to modify EC morphology and biological activity. This paper describes a self-contained microcirculatory EC culture system that efficiently studies such effects of shear stress on EC alignment and elongation in vitro. The culture system is composed of elastomeric microfluidic cell shearing chambers interfaced with computer-controlled movement of piezoelectric pins on a refreshable Braille display. The flow rate is varied by design of channels that allow for movement of different volumes of fluid per variable-speed pump stroke. The integrated microfluidic valving and pumping system allowed primary EC seeding and differential shearing in multiple compartments to be performed on a single chip. The microfluidic flows caused ECs to align and elongate significantly in the direction of flow according to their exposed levels of shear stress. This microfluidic system overcomes the small flow rates and the inefficiencies of previously described microfluidic and macroscopic systems respectively to conveniently perform parallel studies of EC response to shear stress.     

Ethanol and lactic acid production using sap squeezed from old oil palm trunks felled for replanting

Old oil palm trunks that had been felled for replanting were found to contain large quantities of high glucose content sap. Notably, the sap in the inner part of the trunk accounted for more than 80% of the whole trunk weight. The glucose concentration of the sap from the inner part was 85.2 g/L and decreased towards the outer part. Other sugars found in relatively low concentrations were sucrose, fructose, galactose, xylose, and rhamnose. In addition, oil palm sap was found to be rich in various kinds of amino acids, organic acids, minerals and vitamins. Based on these findings, we fermented the sap to produce ethanol using the sake brewing yeast strain, Saccharomyces cerevisiae Kyokai no.7. Ethanol was produced from the sap without the addition of nutrients, at a comparable rate and yield to the reference fermentation on YPD medium with glucose as a carbon source. Likewise, we produced lactic acid, a promising material for bio-plastics, poly-lactate, from the sap using the homolactic acid bacterium Lactobacillus lactis ATCC19435. We confirmed that sugars contained in the sap were readily converted to lactic acid with almost the same efficiency as the reference fermentation on MSR medium with glucose as a substrate. These results indicate that oil palm trunks felled for replanting are a significant resource for the production of fuel ethanol and lactic acid in palm oil-producing countries such as Malaysia and Indonesia.     

Palm-Based Nonionic Surfactants as Emulsifiers for High Internal Phase Emulsions

In the present study, a series of as-synthesized palm-based nonionic surfactants with various hydrophile–lipophile balance values were successfully synthesized. The critical micelle concentration and the Gibbs energy of the surfactants were determined and discussed. For the first time, the surfactants were used to stabilize three-component olein oil-in-water high internal phase emulsions, with an oil volume fraction of 0.85, and which were easily prepared by one-pot homogenization. Proof of high stability was confirmed by the satisfactory rheological profiles and further enhanced by a three-month storage exercise at an elevated temperature which showed no significant physical and rheological changes. These results suggest that low concentration of the surfactants efficiently stabilized the emulsions with high content of oil. Based on the optical micrograph observation, an average droplet size of less than 10 μm increased with increasing ethylene oxide chain length and temperature. The varying degree of viscosity resulted from the various ethylene oxide chain lengths of the surfactants. The hydration efficacy of the emulsions was examined in vivo using a corneometer. The impressive hydration efficacy of olein oil suggests that it could well be a potential moisturizing lipid which might interest dermatologists.     

Electrochemical Formation of Polypyrrole-carboxymethylcellulose Conducting Polymer Composite Films

1.IntroductionConjugated polymers such as polypyrrole(PPY),polyaniline,polythiophene and polyphenylene etc.whichexhibit significant level of electrical conductivity andhence are termed as conducting polymers,have gotversatile promising applications in the field of energystorage[1],sensors[2],electronic and optical devices[3]andso on.Many researches have been conducted to pro-duce composites or blends of conducting polymer filmswith some insulating polymers in order to overcome thedrawbacks su…