Zn uptake by Cladophora glomerata

The uptake of zinc by Cladophora glomerata at different pH-values, light conditions and exposure periods is reported. Zinc uptake was pH-dependent, with uptake increasing with rising pH. Uptake was greatest within the first two hours of exposure and was greater in light than in darkness due to increased pH. All results support the dominance of adsorptive uptake of zinc by Cladophora.     

山西云蒙山油松种群的年龄结构和动态特征

本文用样方法研究了山西云蒙山油松种群的年龄结构、存活曲线和数量动态规律,并且讨论了油松种群数量动态和群落演替的关系,结果表明:油松种群具有增长型和衰退型的动态特征,影响油松种群数量的内在机制主要是种内光资源的竞争。尽管大多数油松种群处于不断衰减状态,但其群落结构及性质在较长时期内将不会发生显著的变化。     

Adsorptive transfer stripping voltammetry: Determination of nanogram quantities of DNA immobilized at the electrode surface

In adsorptive transfer stripping voltammetry (AdTSV), DNA is first adsorbed at the electrode, the electrode is washed and transferred (with the adsorbed layer) in the medium not containing DNA, and voltammetric analysis is performed in this medium. Adsorption can be performed from a drop of DNA solution, which makes it possible to reduce the volume of the analyzed sample by two orders of magnitude as compared to that of conventional voltammetry. With the hanging mercury drop electrode the limit of detection of single-stranded DNA is below 0.1 micrograms/ml; thus if the adsorption is performed from a 10-microliter drop of DNA solution subnanogram quantities of single-stranded DNA are sufficient for the analysis. In AdTSV the behavior of single- and double-stranded DNAs markedly differ from each other in a manner similar to that in the conventional voltammetric or polarographic analysis; AdTSV can thus be used in DNA structure analysis. In AdTSV the DNA transport and its adsorption at the electrode are separated from the electrode process; due to this fact it is possible (a) to perform the voltammetric analysis of DNA from media not suitable for voltammetric analysis of the conventional type, (b) to study the interaction of immobilized DNA with other substances in solution without the results of the voltammetric analysis being influenced by DNA interactions in the bulk of solution, and (c) to exploit the differences of adsorbability of DNA and other substances in order to separate them on the electrode.     

Plant availability of applied and native boron in soils with diverse properties

Laboratory and greenhouse research was conducted to study effects of soil properties on the availability of native and applied B in 14 Virginia soils. Boron absorption could be described by the Langmuir equation in 12 of the 14 soils, and maximum B adsorption (Vmax) in these 12 soils ranged from 3.3 to 26.5 mg kg⁻¹. A multiple regression equation, −19.3+3.51 pH+0.048 clay content, accounted for 89.6% of the variation in Vmax for the 12 soils. Curvilinear relationships (α=0.01) occurred between B in corn (Zea mays L.) tissue from native B and hot-water soluble B, mannitol exchangeable B, and NH₄-acetate and Mehlich III extractable B. Among these four procedures, mannitol exchangeable B correlated most closely (r=0.923) with B in corn tissue from native B. From 0.4 to 13.5% of the applied B was absorbed by corn plants and translocated to shoots. Curvilinear relationships (α=0.01) occurred between B in corn tissue from applied B and soil clay content, NH₄-oxalate extractable Al and Fe, and acidified NH₂OH·HCl extractable Mn. It is evident from these relationships that soil clay and oxyhydroxides of Al, Fe, and Mn have an affinity to adsorb B in somewhat unavailable forms.     

基于海藻酸钠羟基改性的MPEG原位共价修饰微胶囊及抗蛋白性能

目的:通过对海藻酸钠链段羟基位点改性制备甲氧基聚乙二醇(MPEG)原位共价修饰的海藻酸钠/壳聚糖(AC)微胶囊,在保证MPEG修饰微胶囊机械强度不受影响的基础上,有效提高表面MPEG修饰密度,实现兼具良好机械稳定性及抗蛋白性能的微胶囊制备方法。方法:利用溴化氰对海藻酸钠羟基进行活化并将末端氨基的点击化学linker(BAT)接枝在主链上进而制备MPEG原位共价修饰微囊A_(B(OH))CP_N,用球磨法表征微囊机械强度,用Ig G和Fgn为模型考察微囊表面抗蛋白吸附性能,以L929细胞在其二维模拟平板膜上的黏附情况作为衡量指标,考察MPEG修饰微胶囊表面细胞粘附情况,并最终通过体内移植考察MPEG修饰微囊的生物相容性。结果:基于海藻酸钠羟基位点的MPEG原位共价修饰微胶囊能够实现与常规条件制备的微胶囊接近的机械强度;同时与对照组相比Ig G吸附量降低87.4%,Fgn吸附量降低75.5%,实现了良好的抗蛋白吸附性能;二维模拟平板膜表面L929细胞粘附情况显著改善,细胞粘附数与对照组相比降低了76.9%;体内移植结果证明MPEG修饰微囊细胞粘附极少,微囊与纤维层分离明显。结论:基于海藻酸钠羟基位点的MPEG原位修饰能够实现兼具良好机械稳定性及抗蛋白吸附性能的微胶囊。     

Application of a fluorescent biosensor based‐on magneto‐γ‐Fe2O3–methyldopa nanoparticles for adsorption of human serum albumin

Understanding and controlling the interaction between the polymer methyldopa (2‐amino‐3‐(3,4‐dihydroxyphenyl)‐2‐methyl‐propanoic acid) (PMDP)–γ‐Fe₂O₃ nanoparticles and biological fluids is important if the potential of nanoparticles (NPs) in biomedicine is to be realized. Physicochemical studies on the interactions between proteins and NPs are influenced by the surface properties of the NPs. To identify the effects of the NP surface, interactions between human serum albumin (HSA) and PMDP–γ‐Fe₂O₃ NPs were investigated. Here, the adsorption of HSA onto small (10–30 nm diameter) PMDP–γ‐Fe₂O₃ NPs was quantitatively analyzed using spectroscopic methods. The fluorescence quenching data were checked for the inner‐filter effect, the main confounding factor in the observed quenching. The binding constants, K_a, were calculated at different temperatures, using a nonlinear fit to the experimental data, and the thermodynamic parameters ?H, ?S and ?G were given. The obtained thermodynamic signature suggests that hydrophobic interactions at least are present. This result indicates that the structure of the protein turns from a structureless denatured state at pH 3 into an ordered biologically active native state on addition of PMDP–γ‐Fe₂O₃ NPs. Copyright © 2015 John Wiley & Sons, Ltd.     

In situ green synthesis of highly fluorescent Fe2O3@CQD/graphene oxide using hard pistachio shells via the hydrothermal‐assisted ball milling method

In this study, highly photoluminescent and photocatalytic Fe₂O₃@carbon quantum dots/graphene oxide nanostructures were synthesized using ball milling‐assisted hydrothermal synthesis with hard pistachio shells. Different analyses, such as X‐ray diffraction, energy dispersive X‐ray spectroscopy, and Fourier transform infrared spectroscopy were used to study the product structure. Scanning electron microscopy and transmission electron microscopy images were used to study product size and morphology. Optical properties of the as‐synthesized nanomaterials were investigated using ultraviolet–visible light and photoluminescence analyses. To increase photoluminescence intensity, ethylene diamine tetraacetic acid, polyethylene glycol, polyvinylpyrrolidone, and acetylacetonate anions were used to modify the product surface. Thermal stability of the product was studied using thermal gravimetric analysis. Finally, photocatalytic activity and surface adsorption of the product were investigated; the produce was found to be highly photoluminescent with high photocatalytic and surface activities.     

Magnitude of forward trunk flexion influences upper limb muscular efforts and dynamic postural stability requirements during sitting pivot transfers in individuals with spinal cord injury

The purpose of this study was to investigate the effects of imposing different degrees of forward trunk flexion during sitting pivot transfers on electromyographic activity at the leading and trailing upper limb muscles and on dynamic stability requirements. Thirty-two individuals with a spinal cord injury performed three types of sitting pivot transfers: natural technique, exaggerated forward trunk flexion and upright trunk position. Ground reaction forces, trunk kinematics, and bilateral electromyographic activity of eight upper limb muscles were recorded. Electromyographic data were analyzed using the area under the curve of the muscular utilization ratio. Dynamic stability requirements of sitting pivot transfers were assess using a dynamic equilibrium model. Compared to the natural strategy, significantly greater muscle activities were found for the forward trunk flexion condition at the anterior deltoid and both heads of the pectorialis major, whereas the upright trunk strategy yielded greater muscle activity at the latissimus dorsii and the triceps. The forward flexed condition was found to be more dynamically stable, with a lower stabilizing force, increased area of base of support and greater distance traveled. Thus, transferring with a more forward trunk inclination, even though it increases work of few muscles, may be a beneficial trade-off because increased dynamic stability of this technique and versatility in terms of potential distance of the transfer.     

A study of the adsorption of bacterial cells on porous materials

The paper presents experimental data on the adsorption of bacterial cells on porous materials.Translated from Mikrobiologiya, Vol. 73, No. 6, 2004, pp. 810–816.Original Russian Text Copyright © 2004 by Samonin, Elikova.