γ全吸收型探测装置探测效率的实验与模拟

为精确测量keV能区中子俘获反应截面,中国原子能科学研究院核数据重点实验室基于中国散裂中子源反角白光中子源建成了国内首套γ全吸收型BaF₂探测装置。为获得重要的实验参数装置对γ射线的探测效率曲线,对单个BaF₂探测器模块能谱的测量数据与模拟结果进行比较。结果表明,测量¹³⁷Cs和⁶⁰Co源得到的实验结果与MCNP和GEANT4的模拟结果吻合较好,验证了模拟计算得到的探测效率曲线的可靠性,可用于中子俘获反应截面的在线测量。     

气动柔性球关节的模糊PID控制

介绍了新型气动柔性球关节，讨论了其控制方法。综合模糊控制和PID控制的特点。设计了针对气动柔性球关节的模糊PID控制器，实现对球关节弯曲角度、偏转方向等系统参数的动态控制。实验结果表明，模糊PID控制可以实时准确地对气动柔性球关节进行控制。设计的控制系统可以作为气动柔性球关节的有效控制系统，用于进行相关研究。     

5'-Amino acid esters of antiviral nucleosides, acyclovir, and AZT are absorbed by the intestinal PEPT1 peptide transporter

PURPOSE: General use of nucleoside analogues in the treatment of viral infections and cancer is often limited by poor oral absorption. Valacyclovir, a water soluble amino acid ester prodrug of acyclovir has been reported to increase the oral bioavailability of acyclovir but its absorption mechanism is unknown. This study characterized the intestinal absorption mechanism of 5' -amino acid ester prodrugs of the antiviral drugs and examined the potential of amino acid esters as an effective strategy for improving oral drug absorption. METHODS: Acyclovir (ACV) and Zidovudine (AZT) were selected as the different sugar-modified nucleoside antiviral agents and synthesized to L-valyl esters of ACV and AZT (L-Val-ACV and L-Val-AZT), D-valyl ester of ACV (D-Val-ACV) and glycly ester of ACV (Gly-ACV). The intestinal absorption mechanism of these 5' -amino acid ester prodrugs was characterized in three different experimental systems; in situ rat perfusion model, CHO/hPEPT1 cells and Caco-2 cells. RESULTS: Testing 5' -amino acid ester prodrugs of acyclovir and AZT, we found that the prodrugs increased the intestinal permeability of the parent nucleoside analogue 3- to 10-fold. The dose- dependent permeation enhancement was selective for L-amino acid esters. Competitive inhibition studies in rats and in CHO cells transfected with the human peptide transporter, hPEPT1, demonstrated that membrane transport of the prodrugs was mediated predominantly by the PEPT1 H+/dipeptide cotransporter even though these prodrugs did not possess a peptide bond. Finally, transport studies in Caco-2 cells confirmed that the 5' - amino acid ester prodrugs enhanced the transcellular transport of the parent drug. CONCLUSIONS: This study demonstrates that L-amino acid-nucleoside chimeras can serve as prodrugs to enhance intestinal absorption via the PEPT1 transporter, providing a novel strategy for improving oral therapy of nucleoside drugs.     

Nebivolol: comparison of the effects of dl-nebivolol, d-nebivolol, l-nebivolol, atenolol, and placebo on exercise-induced increases in heart rate and systolic blood pressure

Congenital subluxation of the peroneal tendons is an uncommon, but not rare condition. In almost all cases, it will spontaneously resolve without requiring any treatment. Presented is a case report of the condition affecting the patient bilaterally. The subluxation did not resolve and the patient was subsequently treated with a modification of the Kelly procedure.     

生物陶瓷增韧前后的比较研究

通过扫描电子显微镜对氧化锆增韧的羟基磷灰石和纯羟基磷灰石的裂纹扩展和断口形貌特征的观察，发现增韧的羟基磷灰石是以沿晶方式断裂，而纯羟基磷灰石是以解理方式断裂。本文分析了造成增韧前后两种材料不同断裂方式的机制，并讨论了颗粒增韧生物陶瓷的机理。     

Characteristics of DNA Comet, Photostimulated Luminescence, Thermoluminescence and Hydrocarbon in Perilla Seeds Exposed to Electron Beam

ABSTRACT: Detection characteristics of perilla seeds exposed to electron beam doses of 0 to 2 kGy were investigated. DNA comet assay, photostimulated luminescence (PSL) and thermoluminescence (TL) measurements, and hydrocarbon determinations by GC-MS were carried out. The irradiated samples showed comets with longer tails (152 ± 6 mm) than did nonirradiated samples (35 ± 11 mm). PSL values (photon counts) for the irradiated samples were more than 7865; whereas those of nonirradiated samples were less than 294. TL ratios (Glow 1/Glow 2) obtained from nonirradiated samples were less than 0.01 and above 0.48 from irradiated ones. The prominent radiation-induced hydrocarbons were 16:2, 16:3, 17:1, and 17:2, of which 16:2 was the most abundant.     

Use of pentastarch solution in the treatment of patients with hemorrhagic hypovolemia: randomized phase II study in the emergency room

The weeping fig, Ficus benjamina (Fb), is a relatively common indoor allergen. Many cases of perennial allergic rhinoconjunctivitis and allergic asthma caused by Fb hypersensitivity are not detected. These patients typically have proven sensitization to housedust mites and do not improve after avoidance of exposure (encasing) and specific immunotherapy. The number of Fb sensitizations is increasing in Germany, which can partly be explained by the cross-reactivity between Hevea brasiliensis (Hb) latex and Fb and the rapidly increasing number of mostly occupational latex allergies. But Fb itself is a potential sensitizer which is widely spread as ornamental plant in homes and offices. As relevant indoor allergen Fb ranks third after housedust mites and pets but before molds among our allergy patients. For diagnosis, prick-tests with Fb-latex seem to be more sensitive than in vitro-methods (RAST, CAPRAST). Fb plants should not be kept in the homes of atopic individuals or persons with latex (Hb) allergy.     

The rare metastasis of osteosarcoma of a long bone associated with von Recklinghausen''s neurofibromatosis

Benign mesothelioma of the pleura is a very rare tumor. The cells responsible originate from either the mesothelium or the submesothelium. This is why such tumors are described in the literature as fibroma of the pleura, mesothelial fibroma, localized fibrous mesothelioma and monophasic spindle cell tumor. Their growth, is very slow taking several years or even decades. In contrast to the more common malignant mesothelioma of the pleura, it is not related to asbestos exposure. This report deals with a 47-year-old woman patient with a giant benign mesothelioma of the pleura in the region of the right thorax, which was completely removed by thoracotomy.     

Surface temperature measurements on burning wood specimens in the Cone Calorimeter and the effect of grain orientation

Surface temperatures were measured on dry Douglas fir sapwood specimens during Cone Calorimeter tests using thermocouples and an infra-red pyrometer. Good agreement between the thermocouples and the pyrometer was obtained when (1) the emissivity was assumed to be 1.0 and (2) the thermocouples were in good contact with the surface and were not located in the proximity of a fissure. The major fissures were normal to the grain of the wood and the volatiles vented through the fissures. Char oxidation in the region between the vertical fissures resulted in higher surface temperatures.