THE ESTIMATION OF THIOLS AND DISULPHIDES IN BARLEY

Methods are described for the extraction and quantitation of endogenous barley thiols and disulphides. Thiols and disulphides, together with added internal standards, are extracted from ground barley tissues (embryos or degermed grains) and the thiols in the extract are trapped on columns of beaded p-hydroxymercuribenzoyl-agarose (p-HMB-agarose). After elution they are derivatised with 5,5′-dithiobis (2-nitrobenzoic acid) and the derivatives are separated and quantified by hplc. The disulphides in the effluent from the p-HMB-agarose column are collected on a silica-based ion exchange material. After elution they are reduced to thiols and, after derivatisation, they are assayed by hplc. Dry barley embryos contain substantial quantities of glutathione, progressively lesser quantities of oxidised glutathione, cystine and cysteine and traces of γ-glutamyl cysteine and cysteinyl glycine.     

Macrosegregation modeling during direct-chill casting of aluminum alloy 7050

ABSTRACT

A fully transient model of the direct-chill casting process is used to predict the macrosegregation development of aluminum alloy 7050. The ingot diameter, casting speed, superheat, secondary cooling, and thickness of pure Al at startup are varied. Predicted radial composition distributions are fit to Weibull probability density functions at each axial location, and the normalized standard deviation describes the macrosegregation level and the time when the process reaches steady state. The sump depth, steady-state height, and macrosegregation level were most affected by changes in casting speed and ingot diameter. The pure Al dilutes the alloy and delays compositional steady state.     

Functional trait differences between extant exotic,native and extinct native plants in the Hunter River,NSW: a potential tool in riparian rehabilitation

Riparian and riverine systems around the world are subject to human mediated degradation. It is increasingly recognized that rehabilitation of these systems is important to retain biodiversity and important ecosystem services. Plant functional traits represent a potentially useful but underutilized tool in the restoration or rehabilitation of ecosystems such as riparian systems. This study uses a functional trait approach to provide insight into the changes in ecosystem function that have occurred with the loss of native plant species and their replacement by exotics. We examined the plant functional traits associated with extinct native, extant native and extant exotic species in the riparian margin of the Hunter River, New South Wales, Australia. Comparisons of 11 traits were conducted using univariate (analysis of variance and χ ²) and multivariate (principal component analysis and analysis of similarity) methods. Both extant native and extant exotic species had traits associated with a short lived, ruderal strategy: high specific leaf area (SLA), soft leaves, herbaceous growth forms and therophyte life form. In contrast, extinct native species had traits such as low SLA, tough leaves, tree and shrub growth form and phanerophyte life form. This shift in plant trait assemblages associated with the transition from a native to predominately exotic flora has important implications for ecosystem processes in this riverine system. We suggest that such a functional trait approach can be integrated with knowledge of other ecosystem components to provide an understanding of ecosystem function that can be used to guide rehabilitation initiatives. Copyright © 2008 John Wiley & Sons, Ltd.     

Nitrogen mineralization of sewage sludge and composted poultry manure applied to willow in a greenhouse experiment

Nitrogen requirements for production of intensively cultured willow for use as a bioenergy crop coupled with the need for safe disposal of nutrient rich organic wastes provide an opportunity to reduce costs associated with bioenergy plantations. In order to minimize N leaching from sites treated with organic wastes, knowledge of the rate of N mineralization is needed. The objective of this study was to assess N mineralization rates of four organic residuals in a controlled greenhouse environment: composted poultry manure, composted sewage sludge, and anaerobically digested sewage sludge from two different municipalities. Thirty-six weeks after application, disappearance of the mass initially applied ranged from 20% to 50%. Gross nitrogen mineralization rate (N mass released expressed as a percentage of initially applied N) ranged from 12% to 57%. Non-composted treatments released greater amounts of nitrogen than composted treatments. Within composted treatments, net N release was estimated as 325 kgNha⁻¹ for poultry manure and 86 kgNha⁻¹ for sewage sludge. Syracuse and New York City sewage sludges, with 57% and 30% gross N release rates respectively, provided approximately 360 and 240 kg plant available Nha⁻¹, respectively. These estimates of N release suggest that the application rates could be halved and that sufficient N would be provided to meet crop needs and reduce leaching losses.     

Studies on the adsorption of RuN3 dye on sheet-like nanostructured porous ZnO films

The interface between the ZnO and dye directly impacts the dye-sensitized solar cell (DSSC) performance. Nanostructured porous ZnO film was developed by a simple chemical solution process. Scanning electron microscope (SEM) images demonstrated the uniform ZnO films with sheet-like nanostructure. Adsorption studies indicated that the maximum adsorption capacity of RuN₃ dye on the surface of ZnO films was approximately 0.016 mmol RuN₃/g ZnO films. Adsorption studies were conducted at 25 and 40 °C. The results showed that the dye adsorption was significantly influenced by temperatures. Moreover, the problem of the dye aggregation on the ZnO surface was reduced at higher adsorption temperatures. The adsorption chemistry was studied with Raman spectroscopy.     

Delivery Techniques for Enhancing CAR T Cell Therapy against Solid Tumors

Chimeric antigen receptor (CAR) T cells exhibit promising results for cancer immunotherapy. However, the clinical success is still restricted to certain types of blood cancers, while in solid tumors the clinical activity is modest and potential toxicities remain a concern. There are various barriers that prevent CAR T cells from combating solid tumors. Therefore, distinct strategies have been explored to augment CAR T cell proliferative capacity, persistence, and effector function. Altering the tumor microenvironment, and in particular its physiochemical properties and immunosuppressive milieu, is of great significance to facilitate CAR T cell therapy. In this article, emerging strategies implemented to overcome the barriers of CAR T cell therapy in solid tumors are reviewed. Enhancing infiltration, activation, and persistence of CAR T cells has been addressed in several preclinical models. The future development of this field to promote innovation and clinical translation is also discussed.     

Tuning the Poisson's Ratio of Biomaterials for Investigating Cellular Response

Cells sense and respond to mechanical forces, regardless of whether the source is from a normal tissue matrix, an adjacent cell or a synthetic substrate. In recent years, cell response to surface rigidity has been extensively studied by modulating the elastic modulus of poly(ethylene glycol) (PEG)‐based hydrogels. In the context of biomaterials, Poisson's ratio, another fundamental material property parameter has not been explored, primarily because of challenges involved in tuning the Poisson's ratio in biological scaffolds. Two‐photon polymerization is used to fabricate suspended web structures that exhibit positive and negative Poisson's ratio (NPR), based on analytical models. NPR webs demonstrate biaxial expansion/compression behavior, as one or multiple cells apply local forces and move the structures. Unusual cell division on NPR structures is also demonstrated. This methodology can be used to tune the Poisson's ratio of several photocurable biomaterials and could have potential implications in the field of mechanobiology.     

资产管理推动了智能无线设备的发展

智能无线设备获取的数据能让资产管理系统提供范围更为广泛的诊断信息。     

A study of diffusion in poly(ethyleneglycol)-gelatin based semi-interpenetrating networks for use in wound healing

Semi-interpenetrating networks (sIPNs) designed to mimic extracellular matrix via covalent crosslinking of poly(ethylene glycol) diacrylate in the presence of gelatin have been shown to aid in wound healing, particularly when loaded with soluble factors. Ideal systems for tissue repair permit an effective release of therapeutic agents and flow of nutrients to proliferating cells. Appropriate network characterization can, consequently, be used to convey an understanding of the mass transfer kinetics necessary for materials to aid in the wound healing process. Solute transport from and through sIPNs has not yet been thoroughly evaluated. In the current study, the diffusivity of growth factors and nutrients through the polymeric system was determined. Transport of keratinocyte growth factor was modeled by treating the sIPN as a plane sheet into which the protein was loaded. The diffusion coefficient was determined to be 4.86 × 10⁻⁹ ± 1.86 × 10⁻¹² cm²/s. Glucose transport was modeled as flow through a semi-permeable membrane. Using lag-time analysis, the diffusion coefficient was calculated to be 2.25 × 10⁻⁶ ± 1.98 × 10⁻⁷ cm²/s. The results were evaluated in conjunction with previous studies on controlled drug release from sIPNs. As expected from Einstein-Stokes equation, diffusivity decreased as molecular size increased. The results offer insight into the structure-function design paradigm and show that release from the polymeric system is diffusion controlled, rather than dissolution controlled.     

Detection of [U-13C]eicosapentaenoic acid in rat liver lipids using13C nuclear magnetic resonance spectroscopy

Fatty acid carbons are well-resolved in¹³C nuclear magnetic resonance (NMR) spectra of lipid extracts, but application of this methodology to the metabolism of¹³C-labelled fatty acids has not yet been reported. In the present study,¹³C NMR was used to monitor the presence of 98% [U-¹³C]eicosapentaenoic acid (EPA) in liver and carcass lipids 24 h after it had been injected into the stomach of a rat. Natural abundance¹³C NMR spectra of liver total fatty acid extracts were obtained from four control rats for comparison. At 24 h post-injection, quantitative high resolution¹³C NMR showed¹³C enrichment in liver fatty acid extracts was present mainly at olefinic and at the n−1 to n−4 carbons, but¹³C signal intensities for C−1 to C−4 of [U-¹³C]EPA were markedly reduced or absent. Small¹³C resonances, possibly indicative of some¹³C incorporation into docosahexaenoic acid and saturated or monounsaturated fatty acids, were present in spectra of liver fatty acids. Liver and carcass fatty acid composition was similar in both the controls and the EPA-injected rat, suggesting little accumulation of the injected [U-¹³C]EPA after 24 h. We conclude that the carbon-specific data provided by¹³C NMR of lipid extracts may be useful in monitoring the fate of individual carbons during tracer studies using¹³C-labelled fatty acids.