A study of ionization electrons drifting large distances in liquid and solid argon

A two liter gridded ionization chamber was built and operated repeatedly to study electron transport in liquid and solid argon over distances up to 10 cm in drift fields of 0.01–2 kV/cm. A detailed analysis of the ionization pulse shape was performed, yielding information on both the degree of purity of the liquid and the electron drift velocity. Argon with an impurity concentration less than 0.2 ppb oxygen equivalent was obtained with a simple purification system. The measured attenuation length extrapolates to 7.5 m for liquid argon and to 1 m for solid argon at a drift field of 1 kV/cm.     

Reconstitution of Monocyte Subsets and PD-L1 Expression but Not T Cell PD-1 Expression in Obstructive Sleep Apnea Patients upon PAP Therapy

Obstructive sleep apnea (OSA) is characterized by nocturnal breathing intermissions resulting in oxidative stress and eventually, a low-grade systemic inflammation. The study aimed to investigate the impact of positive airway pressure (PAP) therapy on the inflammatory milieu as measured by monocyte and T cell phenotypic alterations. Participants were assessed for their OSA severity before PAP therapy and about six months later, including patient-reported outcome and therapy usage by telemetry readout. The distributions of the CD14/CD16-characterized monocyte subsets as well as the CD4/CD8-characterized effector T cell subsets with regard to their PD-1 and PD-L1 expression were analyzed by flow cytometry from blood samples. Data of 25 patients revealed a significant reconstitution of the monocyte subset distribution and a decrease in PD-L1 expression on pan-monocytes and CD8⁺ T cells without an association to initial AHI and overweight. The PD-1 expression was still increased on T cell subsets, especially on CD4⁺ TH17/22 cells. We conclude that PAP therapy might have a rapid effect on the monocyte phenotype and overall PD-L1 expression levels. However, T cell immune alterations especially on TH17/22 cells persist longer, indicating an ongoing disturbance of the adaptive immune system.     

Screener3D:a gaseous time projection chamber for ultra-low radioactive material screening

In experiments searching for rare signals,back-ground events from the detector itself are some of the major factors limiting search sensitivity.Screening for ultra-low radioactive detector materials is becoming ever more essential.We propose to develop a gaseous time projection chamber(TPC)with a Micromegas readout for radio screening.The TPC records three-dimensional tra-jectories of charged particles emitted from a flat sample placed in the active volume of the detector.The detector can distinguish the origin of an event and identify the particle types with information from trajectories,which significantly increases the screening sensitivity.For a particles from the sample surface,we observe that our proposed detector can reach a sensitivity higher than 100 p Bq m-2 within two days.     

Chemical and Morphological Changes of Vacuum-Plasma-Sprayed Hydroxyapatite Coatings during Immersion in Simulated Physiological Solutions

The purpose of this investigation was to study the behavior of vacuum-plasma-sprayed hydroxyapatite (VPS-HA) coatings in a defined simulated physiological environment that mimics the conditions that the material experiences after implantation in the human body. Commercially available and clinically used HA coatings on titanium alloy substrates were immersed in an inorganic simulated body fluid (SBF) with ion concentrations that were almost equal to those of human blood plasma and in fetal calf serum (FCS) for time periods of 1, 3, 7, 14, and 28 days. At each time interval, the VPS-HA coatings were analyzed using scanning electron microscopy, X-ray diffractometry, Fourier transform infrared spectroscopy, and inductively coupled plasma-atomic emission spectroscopy. The as-received VPS coatings consisted of HA as the main phase component; in addition, small concentrations of tricalciumphosphate (TCP) were determined to be present. During immersion in SBF, transformation of the peripheral area of the VPS coating to a regular spherical shape was observed. Concentration measurements of the immersion solution indicated that dissolution of the more-soluble TCP started within the first day. At the same time, precipitation of a carbonate-containing, marginally crystalline calcium phosphate with very small coherently scattering domains was observed. In FCS, the dissolution of calcium and phosphorus was observed; however, the precipitation of the new calcium phosphate layer was retarded by the presence of proteins, which indicates their important role in the ion-exchange mechanisms. In both solutions, the coating integrity was not adversely affected, which indicates the high stability of VPS-HA coatings in a simulated physiological environment.     

Coincidence timing of Schottky CdTe detectors for tomographic imaging

Schottky CdTe detectors are good candidates for large pixel array imagers. For use of such arrays in Positron Emission Tomography (PET) the coincidence timing of the detectors is very important, since it reduces the background from random coincidences. The coincidence timing of a small 2×2×1 mm³ detector has been measured as 11.6 ns, and thus is not much worse than the timing of BGO scintillators, commonly used in PET.     

干式双离合器已立足于自动变速箱市场

自大众公司2008年初发布首款采用干式双离合器自动变速箱的高尔夫乘用车以来,广大的终端用户和汽车专业人士开始熟知这一技术。在各种出版物和对比分析中,给系统赢得了高度的评价,他达到甚至超过了人们对其驾驶性能及燃油经济性的期望值。     

Waterborne polyurethanes

A major change in coatings technology was caused by the restrictions on volatile organic compounds (VOC) in coatings. These government regulations combined with performance advantages were the key to the success of waterborne polyurethanes. The production and chemistry of waterborne one-component polyurethanes and reactive two-component systems are discussed. Examples for their application, predominantly in the field of surface coatings, are given.     

Status of delayed-neutron precursor data: half-lives and neutron emission probabilities

We present in this paper a compilation of the present status of experimental delayed-neutron precursor data; i.e. β-decay half-lives (T_1/2) and neutron emission probabilities (P_n) in the fission-product region (27 ≤ Z ≤ 57). These data are compared to two model predictions of substantially different sophistication: (i) an update of the empirical Kratz-Herrmann formula (KHF), and (ii) a unified macroscopic-microscopic model within the quasi-particle random-phase approximation (QRPA). Both models are also used to calculate so far unknown T_1/2 and P_n values up to Z = 63. A number of possible refinements in the microscopic calculations are suggested to further improve the nuclear-physics foundation of these data for reactor and astrophysical applications.