Far-infrared magnetospectroscopy on epitaxial zero-gap and wide-gap semiconductor layer systems

Far-infrared magnetotransmission measurements have been performed on MBE-grown HgTe and CdTe epilayers. The results on the HgTe samples can be understood by the standard Pidgeon-Brown model for bulk HgTe. For the CdTe layers, transitions were only observed under illumination by visible light. The spectra are dominated by the 1s→2p transition of the shallow hydrogen-like impurity. These transitions are persistent with a life time of the order of magnitude of one second.     

Potent piperazine hydroxyethylamine HIV protease inhibitors containing novel P3 ligands

The 2-isopropyl thiazolyl group is a highly optimized P3 ligand for C2 symmetry-based HIV protease inhibitors, as exemplified in the drug ritonavir. Here we report that incorporation of this P3 ligand into a piperazine hydroxyethylamine series also yielded novel, highly potent inhibitors. In tissue culture assays, the presence of human serum was less deleterious to the activity of these inhibitors than to that of ritonavir. Furthermore, potent activity against ritonavir resistant HIV was observed.     

一个C＋＋的垃圾收集框架

在所有对C 的抱怨中,声音最响的可能就是“C 没有垃圾收集机制”了。那些使用过更先进的语言(例如Java)的程序员会发现:C 既难学又难用,而且还很容易出错,因为你必须手工管理内存的使用情况。在某种意义上来说,他们是对的;但另一方面,那些死忠的C 程序员们却又对“把控制权拱手交给垃圾收集系统”的做法恨之入骨。本文介绍了一个兼顾易用性和安全性的C 垃圾收集框架。读者可以在CSDN网站《程序员》频道下载本文示例代码。     

A 2 MV Van de Graaff accelerator as a tool for planetary and impact physics research

Investigating the dynamical and physical properties of cosmic dust can reveal a great deal of information about both the dust and its many sources. Over recent years, several spacecraft (e.g., Cassini, Stardust, Galileo, and Ulysses) have successfully characterised interstellar, interplanetary, and circumplanetary dust using a variety of techniques, including in situ analyses and sample return. Charge, mass, and velocity measurements of the dust are performed either directly (induced charge signals) or indirectly (mass and velocity from impact ionisation signals or crater morphology) and constrain the dynamical parameters of the dust grains. Dust compositional information may be obtained via either time-of-flight mass spectrometry of the impact plasma or direct sample return. The accurate and reliable interpretation of collected spacecraft data requires a comprehensive programme of terrestrial instrument calibration. This process involves accelerating suitable solar system analogue dust particles to hypervelocity speeds in the laboratory, an activity performed at the Max Planck Institut fu?r Kernphysik in Heidelberg, Germany. Here, a 2 MV Van de Graaff accelerator electrostatically accelerates charged micron and submicron-sized dust particles to speeds up to 80 km s(-1). Recent advances in dust production and processing have allowed solar system analogue dust particles (silicates and other minerals) to be coated with a thin conductive shell, enabling them to be charged and accelerated. Refinements and upgrades to the beam line instrumentation and electronics now allow for the reliable selection of particles at velocities of 1-80 km s(-1) and with diameters of between 0.05 μm and 5 μm. This ability to select particles for subsequent impact studies based on their charges, masses, or velocities is provided by a particle selection unit (PSU). The PSU contains a field programmable gate array, capable of monitoring in real time the particles' speeds and charges, and is controlled remotely by a custom, platform independent, software package. The new control instrumentation and electronics, together with the wide range of accelerable particle types, allow the controlled investigation of hypervelocity impact phenomena across a hitherto unobtainable range of impact parameters.     

The duration of viral suppression during protease inhibitor therapy for HIV-1 infection is predicted by plasma HIV-1 RNA at the nadir

OBJECTIVE: To determine markers that are associated with the durability of virologic response to therapy with HIV protease inhibitors in HIV-infected individuals. DESIGN: This study encompassed two retrospective analyses of the duration of virologic response to protease inhibitor therapy. The first analysis included 29 patients receiving either monotherapy or combination therapy with the protease inhibitor ritonavir whose plasma HIV RNA levels rebounded from the point of greatest decline with mutations associated with resistance to ritonavir. The second analysis included a cohort of 102 patients who initially responded to randomized treatment with either monotherapy with ritonavir or combination therapy with ritonavir and zidovudine. METHODS: Durability of response was defined as the time from the initiation of therapy to the point at which plasma HIV RNA displayed a sustained increase of at least 0.6 log10 copies/ml from the nadir value. In the first analysis, durability of response was analyzed with respect to baseline HIV RNA, HIV RNA at the nadir, and the drop in HIV RNA from baseline to the nadir. In the second analysis, time to rebound was examined using Kaplan-Meier analysis, stratifying by either baseline HIV RNA or HIV RNA at the nadir. RESULTS: In both analyses, the durability of response was not highly associated with either baseline RNA or the magnitude of RNA decline from baseline. Instead, a strong relationship was observed between the durability of response and the nadir plasma HIV-1 RNA value (P < 0.01). The nadir in viral load was generally reached after 12 weeks of randomized therapy. CONCLUSIONS: Viral RNA determinations at intermediate timepoints may be prognostic of impending virologic failure of protease inhibitor therapy. Therapeutic strategies that allow intensification of initial antiretroviral regimens in the subset of patients with incomplete virological response before the emergence of high level resistance should be investigated.     

Study on the Microstructure of Internally Oxidized Ag–Sn–In Alloys

The microstructures of five internally oxidized Ag–Sn–In materials were investigated using ion polishing, field emission scanning electron microscopy and electron backscatter diffraction. The ion polished sections showed a subtle material contrast in the oxide particles that could be attributed to different oxide phases generated during internal oxidation. The phases could be identified as tetragonal SnO₂ that surrounds the cubic In₂O₃ core of the combined oxide particles. It is shown that In₂O₃ exhibits an orientation relationship to the Ag matrix and for SnO₂ and Ag another orientation relationship is likely. Interrupted internal oxidation experiments were applied to identify the growth mechanism of the oxide particles. A consistent view on the role of In during the internal oxidation of Ag–Sn–In alloys as heterogeneous nucleation agent of SnO₂ is presented.     

Characterisation of a chromatographically produced anti-D immunoglobulin product

A chromatographic fractionation method has been developed for the production of a liquid-stable anti-D immunoglobulin product for intravenous and intramuscular use. An immunoglobulin fraction, highly enriched with anti-D immunoglobulins, was isolated by cation-exchange column chromatography and further polished, first by anion-exchange chromatography, followed by an aluminium hydroxide gel treatment. The process includes two specific steps for virus inactivation and removal, namely S/D treatment and nanofiltration. The overall anti-D process yield is about 56%. The final product is stabilised with human albumin and glycine and placed in ready-to-use syringes. The anti-D product was shown to be stable in liquid state for at least 30 months at 4 degrees C.     

Conductive radical anion salts of poly(butadiene-b-4-vinylpyridine) blockcopolymers

Summary Poly (1,4-butadiene-b-4-vinylpyridine) blockcopolymers are made conductive by formation of the complex salt of the 4-VP-block with tetracyanoquinodimethane (TCNQ). Microphase separated morphologies are obtained where the conductive 4-VP phase is continous or forms a network on a submicron scale in a continous elastomer phase. While the absolute value of the conductivity of 10^-3–10^-4 Scm^-1 depends on the morphology the activation energy typical for an electron hopping process is approximately the same as in the low molecular weight complex with ethylpyridine.