Production of 230U/226Th for targeted alpha therapy via proton irradiation of 231Pa

(230)U and its daughter nuclide (226)Th are novel therapeutic nuclides for application in targeted alpha-therapy of cancer. We have investigated the feasibility of producing (230)U/(226)Th via proton irradiation of (231)Pa according to the reaction (231)Pa(p,2n)(230)U. The experimental excitation function for this reaction is reported for the first time. Cross sections were measured using thin targets of (231)Pa prepared by electrodeposition and (230)U yields were analyzed using alpha-spectrometry. Beam parameters (energy and intensity) were determined both by calculation using a mathematical model based on measured beam orbits and beam current integrator and by parallel monitor reactions on copper foils using high-resolution gamma-spectrometry and IAEA recommended cross-section data. The measured cross sections are in good agreement with model calculations using the EMPIRE-II code and are sufficiently high for the production of (230)U/(226)Th in clinically relevant amounts. A highly effective separation process was developed to isolate clinical grade (230)U from irradiated protactinium oxide targets. Product purity was assessed using alpha- and gamma-spectrometry as well as ICPMS.     

Progress in AMS measurement of natural 32Si for glacier ice dating

AMS measurement of ³²Si can allow for ice core dating over the last thousand years. Technique developments are reported. Necessary negative-ion yields of 20–30% can now be consistently achieved, and permit an overall efficiency from ice sample to detector of ～1%. A ³⁰Si-spike technique has overcome the problem of extremely low intrinsic silicon concentration, with the added benefit of allowing determination of ppb-level silicon via isotope dilution. Improvements have also been made to the ionization detector in the gas-filled magnet that separates the accelerated ³²Si ions from the intense flux of ³²S ions. Preliminary ³²Si AMS results of snow and ice samples from Mt. Cook National Park, New Zealand, are reproducible, and with ³²Si concentrations 1.2–7.2 mBq/m³ comparable to results from mid-latitude snow samples measured previously via the radiometric technique, demonstrating the feasibility of the method. With these developments, the potential of ³²Si as ice core dating tool is close to being realized, and attempts to determine chronologies for both alpine and Antarctic glaciers are underway.     

奥地利的板材加工技术

去年上半年新建的奥地利潘汉斯（Panhans）机械制造有限公司,前身是安东——潘汉斯工具与机械厂。该公司致力于研发经济地板材锯切,包括纤维板、塑料板和石膏纸箱等板材。它具有30多年的板材锯切的经验。     

Site-Specific Small Molecule Labeling of an Internal Loop in JC Polyomavirus Pentamers Using the π-Clamp-Mediated Cysteine Conjugation

The major capsid protein VP1 of JC Polyomavirus assembles into pentamers that serve as a model for studying viral entry of this potentially severe human pathogen. Previously, labeling of viral proteins utilized large fusion proteins or non-specific amine- or cysteine-functionalization with fluorescent dyes. Imaging of these sterically hindered fusion proteins or heterogeneously labeled virions limits reproducibility and could prevent the detection of subtle trafficking phenomena. Here we advance the π-clamp-mediated cysteine conjugation for site-selective fluorescent labeling of VP1-pentamers. We demonstrate a one-step synthesis of a probe consisting of a bio-orthogonal click chemistry handle bridged to a perfluoro-biphenyl π-clamp reactive electrophile by a polyethylene glycol linker. We expand the scope of the π-clamp conjugation by demonstrating selective labeling of an internal, surface exposed loop in VP1. Thus, the π-clamp conjugation offers a general method to selectively bioconjugate tags-of-interest to viral proteins without impeding their ability to bind and enter cells.     

Model reduction for linear simulated moving bed chromatography systems using Krylov‐subspace methods

Simulated moving bed (SMB) chromatography is a well‐established technology for separating chemical compounds. To describe an SMB process, a finite‐dimensional multistage model arising from the discretization of partial differential equations is typically employed. However, its relatively high dimension poses severe computational challenges to various model‐based analysis. To overcome this challenge, two Krylov‐type model order reduction (MOR) methods are proposed to accelerate the computation of the cyclic steady states (CSSs) of SMB processes with linear isotherms. A “straightforward method” that carefully deals with the switching behavior in MOR is first proposed. Its improvement, a “subspace‐exploiting method,” thoroughly exploits each reduced model to achieve further acceleration. Simulation studies show that both methods achieve high accuracy and significant speedups. The subspace‐exploiting method turns out to be computationally much more efficient. Two challenging analyses of SMB processes, namely uncertainty quantification and CSS optimization, further demonstrate the accuracy, efficiency, and applicability of the proposed methods. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3773–3783, 2014     

Evaluation of the potential of periodically operated reactors based on the second order frequency response function

A new, fast and easy method for analysing the potential for improving reactor performance by replacing steady state by forced periodic operation is presented. The method is based on Volterra series, generalized Fourier transform and the concept of higher-order frequency response functions (FRFs). The second order frequency response function, which corresponds to the dominant term of the non-periodic (DC) component, G₂(ω, −ω), is mainly responsible for the average performance of the periodically operated processes. Based on that, in order to evaluate the potential of periodic reactor operation, it is enough to derive and analyze G₂(ω, −ω). The sign of this function defines the sign of the DC component and reveals whether a performance improvement by cycling is possible compared to optimal steady state process. The method is used to analyze the periodic performance of a continuous stirred tank reactor (CSTR), a plug flow tubular reactor (PFTR) and a dispersive flow tubular reactor (DFTR), after introducing periodic changes of the input concentrations. A homogeneous, n-th order reaction is studied under isothermal conditions.     

Nonrigid microporous PVC sheets: Preparation and properties

The non‐rigid microporous PVC films are prepared by mono‐axially stretching nonporous sheets containing fillers which show an average particle size of 2 to 10 μm. The nonporous PVC film is generated from paste‐like PVC. The influence of recipe components on the mechanical properties, morphological behavior and permeability to water vapor and water was investigated as well as the influence of the stretching ratio. Filled PVC pastes exhibit higher values for viscosity than those of pure polymer mixtures. For processing the compounded paste by means of a doctor blade a low viscosity is required meaning the amount of filler is limited by the resulting paste viscosity. Due to dewetting, the filler initiates the holes of the microporous system during the stretching process. Empirically, a minimum of about 15 vol % filler particles are necessary in order to achieve an interconnected air hole system. Varying the components PVC, plasticiser and filler, PVC membranes could be prepared with high water vapour permeability and high waterproofness simultaneously. To utilize the membranes commercially a continuous preparation process was developed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Membrane topology of recombinant rat liver microsomal glutathione transferase expressed in E. coli

Rat liver microsomal glutathione transferase is a mammalian membrane protein that can be successfully expressed in Escherichia coli in an enzymatically active form. The protein does not form inclusion bodies and is recovered in the membrane fraction. The membrane topology of recombinant rat liver microsomal glutathione transferase expressed in E. coli was investigated by comparing the proteolytic cleavage products from intact and permeabilized spheroplasts. It was shown that lysine-4 of microsomal glutathione transferase is directed towards the outside, whereas lysine-41 faces the inside of the E. coli inner membrane. This shows that microsomal glutathione transferase has an inside-out orientation in E. coli spheroplasts as compared to liver microsomes. This fact enables us to make topology experiments that were previously not possible. Intact spheroplasts treated with pronase yielded a cleavage pattern consistent with two additional exposed segments closer to the C-terminus. Thus a polytopic model is suggested for the membrane association of microsomal glutathione transferase.     

Impact of stress on objectively recorded menopausal hot flushes and on flush report bias.

Investigated the association between stress and both objective (i.e., physiologically recorded) and subjective hot flushes (HFs) among 21 37–71 yr old postmenopausal women who reported having frequent HFs. Ss underwent psychophysiological monitoring during stressful and nonstressful laboratory sessions. Significantly more objective HFs were recorded during the stress session than during the nonstress session. The stress manipulation, however, did not affect Ss' propensity to report HFs. Results suggest that the observed association between reported HFs and stress is not due to changes in report bias. The physiological mechanisms through which stress may stimulate HFs are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)