Preparation of capacitor’s electrode from sunflower seed shell

Series of nanoporous carbons are prepared from sunflower seed shell (SSS) by two different strategies and used as electrode material for electrochemical double-layer capacitor (EDLC). The surface area and pore-structure of the nanoporous carbons are characterized intensively using N₂ adsorption technique. The results show that the pore-structure of the carbons is closely related to activation temperature and dosage of KOH. Electrochemical measurements show that the carbons made by impregnation-activation process have better capacitive behavior and higher capacitance retention ratio at high drain current than the carbons made by carbonization-activation process, which is due to that there are abundant macroscopic pores and less interior micropore surface in the texture of the former. More importantly, the capacitive performances of these carbons are much better than ordered mesoporous carbons and commercial wood-based active carbon, thus highlighting the success of preparing high performance electrode material for EDLC from SSS.     

Modulation of Coordinated Activity across Cortical Layers by Plasticity of Inhibitory Synapses

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Tangential cell migration during layer formation of chick optic tectum

The laminated structure of the optic tectum is formed by radial and tangential cell migration during development. Studies of developing chick optic tectum have revealed two streams of tangential cell migration in the middle and superficial layers, which have distinctive origins, migratory paths, modes of migration, and destinations. We will review the process of the two types of tangential migrations, in order to elucidate their roles in the formation of the optic tectum layers.     

华北地区针叶林下凋落物层化学性质的研究

森林凋落物中贮积了大量的有机、无机养分物质,它是森林土壤自然肥力的重要来源之一。在森林生态系统中,养分物质的内部循环主要是通过凋落物来实现的。在分解、转化过     

The effect of dielectric polarization of the electrode on anomalous temperature effects in the electrical double layer

Monte Carlo simulations and a modified Poisson–Boltzmann (MPB) theory are used to investigate the temperature dependence of the capacitance (around the potential of zero charge) of an electric double layer in the presence of surface polarization due to a dielectric boundary. Within the context of the restricted primitive model planar double layer, whose solvent dielectric constant is ε₂, the cases when the electrode is an insulator (ε₁ = 1), when the electrode and the electrolyte have the same permittivity (ε₁ = ε₂, no polarization), and when the electrode is a conductor (ε₁ → ∞) are studied for the case where the electrolyte concentration is 0.1 M. The simulations reveal a capacitance anomaly, that is, a positive temperature dependence of the capacitance at low temperatures for the former two situations. The MPB theory also shows this effect for these two situations and is in qualitative or better agreement with the simulation data. In these two cases, both the simulations and theory show a dramatic increase of the diffuse layer potential in the temperature regime where capacitance anomaly occurs. However, in the latter situation, where the electrode is metallic, the capacitance always has a negative temperature derivative for the MPB theory and probably also for the simulation data.     

Characterization of B and H blood-group active glycosphingolipids from human B erythrocyte membranes

Two blood group B active glycosphingolipids (B-I and B-II) previously isolated and highly purified from human B erythrocytes [21] were analysed first by degradation with α-D-galactosidase from coffee beans, α-L-fucosidase from bovine kidney and with 0,1 N trichloracetic acid; the native B-glycolipids as well as their degradation products were then investigated by methylation analysis with combined gas chromatography-mass spectrometry, by thin layer chromatography, twodimensional immunodiffusion and by the hemagglutination inhibition technique. Together with the results obtained by mass spectrometry of permethylated glycolipids [26] the following structures were elucidated: α-D-galactopyranosyl-(1 → 3)-[α-L-fucopyranosyl-(1 → 2)]-D-galactopyranosyl-(1 → 4)-N-acetyl-D-glucosaminosyl-(1 → 3)-D-galactopyranosyl-(1 → 4)-D-glucopyranosyl-(1 → 1)-ceramide for the B-I glycosphingolipid and α-D-galactopyranosyl-(1 → 3)-[α-L-fucopyranosyl-(1 → 2)]-D-galactopyranosyl-(1 → 4)-N-acetyl-D-glucosaminosyl-(1 → 3)-D-galactopyranosyl-(1 → 4)-N-acetyl-D-glucosaminosyl-(1 → 3)-D-galactopyranosyl-(1 → 4)-D-glucopyranosyl-(1 → 1)-ceramide for the B-II glycosphingolipid. A H active glycolipid fraction from B erythrocytes further purified by thin layer chromatography was also investigated by methylation analysis. The pattern of its partially methylated alditol acetates was essentially the same as that of the α-galactosidase treated and permethylated B-I glycolipid. It also exhibited strongly precipitating and hemagglutination inhibiting H properties as well as the two α-galactosidase treated B-I and B-II glycosphingolipids. Based upon these data the following tentative structure was proposed: α-L-fucopyranosyl-(1 → 2)-D-galactopyranosyl-(1 → 4)-N-acetyl-D-glucosaminosyl-(1 → 3)-D-galactopyranosyl-(1 → 4)-D-glucopyranosyl-(1 → 1)-ceramide. Gas chromatographic analysis revealed sphingosine and lignoceric, nervonic and behenic acids to be the main components of the ceramide residues of the three glycosphingolipids. From the data presented the H active substance very probably can be regarded as the immediate precursor of the B-I glycosphingolipid from human B erythrocyte membranes.     

The effect of diffusion and convection on the rate of transfer of solutes across an interface

The transfer of substances across the interface between water and a membrane or between water and a solvent occurs in series with transport up to and away from the interface. These processes have been difficult to resolve. Recently D. M. Miller (Biochim Biophys Acta 856: 27–35, 1986) has used a moving drop technique to measure the rates of transfer of short-chain alcohols and tritiated water between water andn-octanol. This technique produces equivalent unstirred layers which are less than about 10 m thick. Based on the trends in the observed rates of phase transfer, he proposes that the transfer is limited by the actual interfacial step. If so, water-oil interfacial transfer would be sufficiently slow to limit the rate of permeation of lipid membranes by these substances. It is shown here that the observed rates of phase transfer can be explained quantitatively if they are limited by convection or by diffusion across the combination of 5–10 m unstirred layers both inside and outside the moving drops. For water, comparison of the observed rates with the rate of evaporation from a clean surface, suggests that the interfacial step at the water-octanol interface is not rate-limiting.     

Selection of Lactobacillus acidophilus strains for use in “acidophilus products”

Recent studies by DNA-DNA hybridization revealed that strains now designated as L. acidophilus, can be divided into several groups and only one group should be classified as L. acidophilus. We studied several phenotypic characteristics in representative strains from the six DNA-homology groups of L. acidophilus. No group specific pattern was observed among the strains for fermentation of eight carbohydrates, growth at 15 and 45°C, resistance to 0.2% oxgall, lysis by lysozyme or sensitivity to 17 antibiotics. However, some differences among groups were observed in -galactosidase (-gal) activity and surface layer (s-layer) protein. Strains in B1 do not have a s-layer or -gal while B2 strains also lack a s-layer but do possess -gal. All strains in groups A1, A2, A3 and A4, capable of growing in lactose, have -gal activity and also have a s-layer composed of protein subunits of different molecular weights (MW). Strains in A1 homology group have a s-layer with 46 Kd protein subunits while strains in other A groups have s-layer protein subunits that varied in MW within each group. On the basis of these two traits several isolates of unknown homology groups have been tentatively placed in A1, B1 or B2 groups. L. acidophilus from A1 group showed strain variation in -gal specific activity and rate of acid production and growth. For use in dietary adjuncts, L. acidophilus strains should be selected for these three and other desirable traits. They should be maintained and grown in media containing lactose.