A nuclease activity has been purified from the nuclei-kinetoplast fraction of Leishmania. This enzyme, termed endonuclease M (Endo M), is shown by electrophoresis in a denaturing polyacrylamide gel to be associated with a single polypeptide of molecular mass 52 kDa. Physical analysis of the enzyme indicates that it has a sedimentation coefficient S20,w of 4.5S, a Stoke's radius of 32.5 A, and a native molecular mass of 53 kDa. The final Mono Q purified Endo M possesses both DNase and RNase activities. It acts as an endonuclease by introducing random single-stranded nicks into the supercoiled DNA molecules, that often leads to its linearization due to nicking at the opposite strands, and subsequent degradation of the DNA with further incubation. Single-stranded DNA is twice preferred to double-stranded DNA as substrate. Single-stranded RNA is also degraded rapidly and is competitive as a substrate with single-stranded DNA. RNA:DNA hybrids, however, are largely resistant to the Endo M digestion. 相似文献
The selection of product portfolios, processing routes and the combination of technologies to obtain a sustainable biorefinery design according to economic and environmental criteria represents a challenge to process engineering. The aim of this research is to generate a robust methodology that assists process engineers to conceptually optimise the environmental and economic performances of biorefinery systems. A novel economic value and environmental impact (EVEI) analysis methodology is presented in this paper. The EVEI analysis is a tool that emerges from the combination of the value analysis method for the evaluation of economic potential with environmental footprinting for impact analysis. The methodology has been effectively demonstrated by providing insights into the performance of a bioethanol plant as a case study. The systematisation of the methodology allowed its implementation and integration into a computer-aided process engineering (CAPE) tool in the spreadsheet environment. 相似文献
Speciation of actinide (An) and lanthanide (Ln) in technologically important ceramics is very important from both fundamental as well as technological aspects. The intrinsic structural flexibility of perovskite containing AO6 and BO12 polyhedra makes them suitable and rich hosts for An and Ln. In this work, emphasis was given to deciphering information such as oxidation state, local dopant site, charge compensating defects, excited state kinetics, and so forth in BaHfO3 (BHO) related to dopant uranium (BHO-U) and cerium (BHO-Ce). Several spectroscopic techniques namely, time-resolved photoluminescence (TRPL), positron annihilation lifetime spectra (PALS), and thermoluminescence (TL) spectroscopy coupled with density functional theory (DFT) were employed to probe the same. Ce and U though are distributed at both Ba and Hf sites, Ce prefers the former, while U prefers the latter site. Uranium on the other hand stabilizes as U6+ in the form of octahedral uranate ion giving green emission. PALS suggested the formation of defects in BHO-Ce and BHO-U with oxygen vacancies predominating in the former whereas BHO-U perovskites are loaded with cation vacancies and vacancy clusters. These cation vacancies are responsible for lower TL output in BHO-U. TL measurements also suggested cerium doping leads to a higher density of deeper traps in BHO-Ce compared to uranium doping in BHO-U which is in concurrence with DFT results and may have implications in designing afterglow phosphors based on perovskite. We believe this work would have a long-term impact on exploring the potential of perovskite for nuclear waste host and afterglow phosphors applications. 相似文献
In this study, response surface methodology (RSM) was employed for the removal of methylene blue (MB) from aqueous solution using neem (Azadirachta indica) bark dust (NBD) as a bioadsorbent. The influence of various process parameters namely initial concentration (500–1,000 mg L?1), bioadsorbent dose [0.20–1.50 g (100 mL)?1], pH (5–12), and stirring rate (250–650 rpm) was taken as an input parameter. A total of 29 biosorption experimental runs were carried out employing the detailed conditions designed by RSM based on the Box–Behnken design (BBD). Response surface plots were studied to determine the interaction effects of main factors and optimum conditions of process. Regression analysis showed good fit of the experimental data to the second-order polynomial model with coefficient of determination (R2) value of 0.9760 and model F value of 40.68. The predicted R2 value is 0.8979. In addition, results reported in this research demonstrated the feasibility of employing NBD as bioadsorbent for MB removal. 相似文献
For tissue engineering purpose two gelatin based polyester urethane scaffolds of different compositions were prepared from
lactic acid, polyethylene glycol 400 (PEG 400) and characterized by FTIR, XRD for their mechanical and morphological properties
using SEM and optical microscopic analyses. Degradation and swelling studies of gelatin based polyester urethane scaffolds
in phosphate buffer saline (PBS) were performed. Human keratinocyte cells were cultured within these scaffolds, which showed
good cell adherence and proliferation. 相似文献
A sensor for metal cations is demonstrated using single and binary mixtures of different thiolated ligands as self-assembled monolayers (SAMs) functionalized on silicon microcantilevers (MCs) with gold nanostructured surfaces. Binding of charged metal ions to the active surface of a cantilever induces an apparent surface stress, thereby causing static bending of the MC that is detected in this work by a beam-bending technique. A MC response mechanism based on changes in surface charge is discussed. The monodentated ligands arranged as SAMs on the MC surface are not expected to fully satisfy the coordination sphere of the detected metals. This leads to lower binding constants than would be expected for chelating ligands, but reversible responses. The modest binding constants are compensated in terms of the magnitudes of responses by the inherent higher sensitivity of the nanostructured approach as opposed to more traditional smooth surface MCs. Response characteristics are optimized in terms of SAM formation time, concentration of ligand solution, and pH of working buffer solution. Limits of detection for the tested mono-, di-, and trivalent metal ions are in low to submicromolar range. The results indicated that shapes and magnitudes of response profiles are characteristics of the metal ions and type of SAM. The response factors for a given SAM with the tested metal ions, or for a given metal with the tested SAMs, varied by roughly 1 order of magnitude. While the observed selectivity is not large, it is anticipated that sufficient ionic recognition contrast is available for selective metal ion identification when differentially functionalized arrays of MCs (different ligands on different cantilevers in the array) are used in conjunction with pattern recognition techniques. 相似文献
In this article a Substrate Integrated Non Radiative Dielectric Guide (SINRD) has been realized with the concept of substrate integration circuits. In SINRD, a specific pattern of air holes have been used grooved in a dielectric substrate to reduce the effective dielectric constant of a particular region. Accordingly, design and implementation of SINRD guides and its applications in millimeter wave subsystems have been investigated by using published literatures. Thereby the concept has been utilized to develop an optimized design flow of SINRD transmission line. Design has been carried out at W band (85–110 GHz) on a high dielectric constant substrate and subsequently dispersion characteristics has been studied subject to transmitted and radiated field configuration.