Physico-chemical and antigenic properties of tetanus and diphtheria toxoids and steps towards improved stability

Physico-chemical, antigenic and immunogenic properties may be altered during microencapsulation of antigens and their release from poly(lactic acid) and poly(lactic-co-glycolic acid) microspheres. Here, the physico-chemical, conformational and antigenic stability of tetanus and diphtheria toxoids was studied in aqueous solutions stressed by elevated temperature and the presence of lactic and glycolic acids. Further, the stabilising effect of albumin was investigated. The analytical tools used were fluorimetry, circular dichroism spectroscopy, turbidimetry, electrophoresis and ELISA. Elevated temperatures altered the physico-chemical and antigenic properties of the toxoids to a greater extent than the acids (50 mM) did. Substantial unfolding and chemical changes of tryptophan were observed upon 1-4 weeks of incubation at 60 degreesC. At 4 degreesC, only minor conformational changes were observed, even in the presence of the acids. Furthermore, 40% of the tetanus toxoid antigenicity was lost after 7 days at 37 degreesC. This loss increased in the presence of the acids. At 60 degreesC, the antigenicity had completely vanished. Very importantly, 0.5% albumin preserved the tetanus antigenicity over 6 weeks' incubation at 37 degreesC, regardless of the presence of glycolic acid. This qualifies albumin as potential stabilising additive for toxoid loaded poly(lactic acid) and poly(lactic-co-glycolic acid) microspheres.     

Stability and convergence analysis of implicit upwind schemes

Von Neumann stability analysis and convergence studies are used to parametrically study the performance capabilities of implicit upwind schemes, such as alternating direction implicit (ADI), diagonally dominant ADI (DDADI), point Gauss–Seidel (DDLU) and line Gauss–Seidel (DDLGS) methods. All the schemes are expressed in a common approximate factorization form, and multi-sweep strategies are formulated within a generalized dual-time framework. Stability analysis reveals that all the schemes are conditionally stable, although they may be rendered unconditionally stable by employing a sufficient number of inner sweeps. Study of high aspect ratio effects reveals the importance of using the min-CFL time-step definition and viscous preconditioning based upon the min-CFL and max-VNN. Stability and convergence studies reveal that the ADI and DDLGS schemes possess attractive convergence properties at all aspect ratios for 2D problems, while the DDADI and DDLU schemes perform worse at high aspect ratios.     

Electrical Transport and Oxygen Exchange in the Superoxides of Potassium,Rubidium, and Cesium

Conductivity, ionic transference number, and chemical diffusion coefficients are determined for KO₂, RbO₂, and CsO₂. Based on such results, a defect‐chemical model is constructed. These superoxides are found to exhibit a total conductivity in the range of 3 × 10^–7 to 5 × 10^–5 S cm^–1 at 200 °C with contributions from ionic and electronic carriers. The ionic conductivity is caused by alkali interstitials and superoxide vacancies as mobile defects, and is found to exceed the n‐type electronic conductivity. ¹⁸O isotope exchange on powder samples (monitoring the gas phase composition) shows that essentially all oxygen can be exchanged. At high pO₂ this largely occurs without breaking of the O–O bond—indicating a sufficient mobility of molecular superoxide species in the solid—and with an effective rate constant that is much higher than for other large‐bandgap mixed conducting materials such as SrTiO₃.     

Interconnection of busbar‐free back contacted solar cells by laser welding

We are presenting the module integration of busbar‐free back‐junction back‐contact (BJBC) solar cells. Our proof‐of‐concept module has a fill factor of 80.5% and a conversion efficiency on the designated area of 22.1% prior to lamination. A pulsed laser welds the Al metallization of the solar cells to an Al foil carried by a transparent substrate. The weld spots electrically contact each individual finger to the Al foil, which serves as interconnect between different cells. We produce a proof‐of‐concept module using busbar‐free cell strips of 25 × 125 mm². These are obtained by laser‐dicing of a 125 × 125 mm² BJBC solar cell. The fill factor of this module is increased by 3.5% absolute compared with the initial cell before laser‐dicing. This is achieved mainly by omitting the busbars and reduction of the finger length. The improvement of the module fill factor results in an increase in the module performance of 0.9% absolute before lamination in comparison with the efficiency of the initial 125 × 125 mm² BJBC solar cell. Hence, this interconnection scheme enables the transfer of high cell efficiencies to the module. Copyright © 2014 John Wiley & Sons, Ltd.     

添加剂之应用及全球洗涤剂发展趋势

一、全球趋势 尽管世界各地的洗涤剂生产,零售和消费情况不尽相同,但是共同点也是显而易见的:我们都致力于开发更高效,更方便,更高兼容性,当然,更低成本的洗涤剂产品.同时,洗涤剂配方确实在上个世纪取得了巨大的进步.     

Epidermal aminopeptidase activity and metabolism as observed in an organized HaCaT cell sheet model

Metabolism studies on organized HaCaT keratinocyte cell sheets are reported. Cells were grown on porous membranes to form organized cell sheets of several cell layers, which were considered as a model of viable epidermis. Metabolism was studied by reflection kinetics, with the top side of the cell sheets in contact with a donor solution and the basal side closed by an impermeable backing layer. Metabolite formation was followed by HPLC of substrate and metabolite in the donor. For comparison, studies with homogenized HaCaT cells were also performed. Model substrates were amino acid amides of 4-methoxy-2-naphthylamine (MNA) (i.e., Ala-MNA, Arg-MNA, Glu-MNA, and Leu-MNA). Also Leu-enkephalin was studied as a model peptide. Except for Glu-MNA, all substrates were metabolized in both the organized cell sheet and in the homogenates. In homogenate studies, saturation of the metabolic reaction was reached at <100 nmol mL(-1) substrate, whereas metabolism in organized cell sheets was below saturation (up to 500 nmol mL(-1)) except for Leu-enkephalin that showed saturation at >100 nmol mL(-1). In homogenates, substrate inhibition was found with Leu-MNA (> approximately 20 nmol mL(-1)) but not with Ala-MNA and Arg-MNA, both of which showed saturation. Differences of homogenates versus organized cell sheets are due to the intact organization and enzyme compartmentation of the cell sheets as opposed to the loss of organization and compartmentation in homogenates. Also, diffusion of substrate into cell sheets may be rate limiting.     

Imaging H2(17)O distribution in a phantom and measurement of metabolically produced H2(17)O in live mice by proton NMR

Previously we suggested a method for indirect detection of H2(17)O via a combination of 1H spin-echo sequence and 17O decoupling. The method is based on the shortening of the water proton T2 due to the residual spin-spin coupling with the 17O nucleus, and on our finding that this shortening is abolished by applying an radio frequency field at the 17O resonance frequency. In the present work we demonstrate how the method can be used for imaging low concentrations of H2(17)O, and report for the first time an application of this method to in vivo detection of H2(17)O in live newborn mice, where the H2(17)O was introduced either directly i.p. or by inhalation of 17O2 where it was formed by oxidative metabolic activity.     

Spatially resolved drying kinetics of multi-component solution cast films for organic electronics

The use of multi-component solvent/additive systems can be beneficial in the manufacturing process of organic and printed electronics because they can provide an extended degree of freedom, in terms of optimized wetting properties or their influence on the molecular ordering during solvent evaporation. For a systematic investigation of the drying process of such systems a technique for the measurement of the evaporation kinetics for micrometer to nanometer thin films is required. Since large area films are drying faster at the edges, we determine the drying kinetics spatially resolved in a linear array of 5 reflectometers simultaneously for single and binary solvent systems for polymer–fullerene (P3HT:PCBM) solutions as used in organic photovoltaic.In order to design a specific drying process, e.g. combined fast and slow evaporation of high or less solving solvents, a spatial resolved numerical investigation of solvent mass transfer is addressed. A numerical approach including the effect of a moving drying front shows reasonable agreement for single and binary solvent systems with spatially resolved experimental data. The effect of the moving drying front accelerates the drying kinetics at a distinct position as the front approaches and must also be considered for integral measurements (e.g. gravimetric experiments).