二维电离室矩阵在放疗的质量保证体系中的应用

肿瘤的放射治疗中,为了检测治疗设备的性能以及确保放疗计划实施的可靠性和准确性,必须具备完善的质量保证体系（Quality Assurance,QA）. 本文研究将德国PTW公司研发的二维电离室矩阵Seven29应用到放疗的日常QA过程中,使用Seven29和与之配套的八角体模或平板体模来测量剂量分布图,并与治疗计划系统计算出来的剂量分布图进行比较. 对治疗设备每月的QA,最重要的项目是检测射线性能的连续性,检测方法是对连续两个月机器性能的参数进行比较. 采用PTW公司的软件VeriSoft和MultiCheck进行数据分析,经大量的实验验证和比较,结果表明二维电离室矩阵是剂量测量和分析的有效工具,其精度高、可靠性强、使用方便,是实现无胶片化和无纸化放疗体系的重要组成部分.     

Vitamin D Reverses Disruption of Gut Epithelial Barrier Function Caused by Campylobacter jejuni

Infections by the zoonotic foodborne bacterium Campylobacter jejuni (C. jejuni) are among the most frequent causes of bacterial gastroenteritis worldwide. The aim was to evaluate the relationship between epithelial barrier disruption, mucosal immune activation, and vitamin D (VD) treatment during C. jejuni infection, using intestinal epithelial cells and mouse models focused on the interaction of C. jejuni with the VD signaling pathway and VD treatment to improve C. jejuni-induced barrier dysfunction. Our RNA-Seq data from campylobacteriosis patients demonstrate inhibition of VD receptor (VDR) downstream targets, consistent with suppression of immune function. Barrier-preserving effects of VD addition were identified in C. jejuni-infected epithelial cells and IL-10^−/− mice. Furthermore, interference of C. jejuni with the VDR pathway was shown via VDR/retinoid X receptor (RXR) interaction. Paracellular leakiness of infected epithelia correlated with tight junction (TJ) protein redistribution off the TJ domain and apoptosis induction. Supplementation with VD reversed barrier impairment and prevented inhibition of the VDR pathway, as shown by restoration of transepithelial electrical resistance and fluorescein (332 Da) permeability. We conclude that VD treatment restores gut epithelial barrier functionality and decreases bacterial transmigration and might, therefore, be a promising compound for C. jejuni treatment in humans and animals.     

重卡正面碰撞强度试验的有限元分析

依据ECE29法规,对重卡驾驶室正面碰撞强度试验进行了有限元仿真。当摆锤正面撞击后,测量结果表明驾驶室方向盘外延到座椅的x向距离大于法规中人胸部厚度,证明了驾驶室具有足够的生存空间。     

Influences of electric pulse on solidification structure of LM-29 Al-Si alloy

The metallographic structure of LM-29 aluminum-silicon alloy modified by electric pulse treatment has been investigated and compared with those untreated. The solidification structure of LM-29 alloy has been analyzed by means of M1AP3 Quantimet image processing and analysis system, and then the solidification process has been analyzed by means of differential scanning calorimetry (DSC). The results indicate that the primary silicon phase was refined remarkably by electric pulse while the tensile strength and elongation properties increased accordingly. Electric pulse treatment can also increase the binding power between silicon clusters and alloy melt matrix, as a result, the precipitation of primary silicon phase is suppressed to meet the demand of supercooling degree for nucleating, correspondingly. The electric pulse modification has great influence on the size of silicon atomic cluster as well as its distribution in the melt, subsequently, leads to the refinement of solidification structure.     

29Si固体核磁共振技术在C-S-H凝胶中的应用进展

C-S-H凝胶作为硅酸盐水泥最主要的水化产物,是影响水泥混凝土行业工程质量的重要因素.本文围绕29Si固体核磁共振技术(29Si NMR)在硅酸盐水泥水化产物应用展开,从水化硅酸钙晶型、C-S-H聚合机理、钙硅比、机械力活化作用、矿物掺合料对C-S-H影响等几方面阐述29Si NMR在硅酸盐水泥水化产物C-S-H凝胶中的应用,提出了利用29Si NMR分析硅酸盐水泥水化产物存在的问题,并展望了29Si NMR在水泥水化领域的发展趋势.     

Influence of template on Si distribution of SAPO-11 and their performance for n-paraffin isomerization

SAPO-11 molecular sieves were synthesized using single agent (i.e. diethylamine (DEA), di-iso-propylamine (DIPA) and di-n-propylamine (DPA)) or a mixture of DEA and DIPA (named DEPA) as the template under hydrothermal conditions. XRD indicated that the directing effect of different templates for AEL structure decreased in the order of DEPA > DPA > DIPA > DEA. ²⁹Si MAS NMR showed that although all SAPO-11 samples synthesized at same Si content, that prepared with the mixed template contained more Si (4Al) sites, whereas Si (nAl, 4-nSi, 0 < n < 4) environments were predominant in the samples synthesized with single template. The results indicated that the mixed template led to a better Si dispersion and then increased the number of total acid sites of SAPO-11. In the isomerization of n-tetradecane over different Pt/SAPO-11 catalysts, the sample prepared with DEPA showed high catalytic activity and selectivity for i-C₁₄, which were related to the most abundant weak acid sites of the sample.     

Fatty Acid Composition, Antioxidant Properties, and Antiproliferative Capacity of Selected Cold-Pressed Seed Flours

Cold-pressed seed flours from pumpkin, parsley, mullein, cardamom, and milk thistle were examined for total oil, fatty acid profile of the oil, total phenolic content (TPC), scavenging activities against peroxyl (ORAC), hydroxyl (HOSC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (RDSC) radicals, and antiproliferative capacity against HT-29 human colon cancer cells. The cold-pressed parsley seed flour contained a very high concentration of total oil—17.6 g/100 g flour—with primarily C18:1 fatty acid at 86.2 g/100 g fatty acids. All other flour oils had relatively high levels of saturated fats, ranging from 39.0 to 62.9 g/100 g fatty acids. The tested seed flours demonstrated significant TPC and free radical scavenging activities. Milk thistle seed flour had the highest TPC value of 25.2 mg gallic acid equivalent per g flour (GAE mg/g) followed by that of parsley seed flour at 8.1 GAE mg/g. Milk thistle seed-flour extract also had significantly higher antioxidant activities than all other extracts against all tested radicals. The milk thistle seed-flour extract had an ORAC value of 1131 μmol trolox equivalents (TE) per g flour (TE μmol/g), a HOSC value of 893 TE μmol/g, and an RDSC value of 61 TE μmol/g. Also, ORAC, HOSC, and TPC values were significantly correlated (P < 0.01) under the experimental conditions. The cold-pressed milk thistle seed flour inhibited the proliferation of HT-29 cancer cells in a dose-dependent manner. Results from this study suggest that these cold-pressed seed flours may serve as natural sources of antioxidants and may be used to improve human health.     

A structural investigation relating to the pozzolanic activity of rice husk ashes

Various factors determine the applicability of rice husk ash (RHA) as a pozzolanic material. The amount and accessibility of reactive sites is thought to be a key factor. A structural study of RHA samples in relation to their reactivity has been performed; Silica in RHA formed by burning rice husk in a laboratory furnace under continuous supply of air have been characterized as a function of incineration temperature, time and cooling regime. The characterization methods included chemical analyses, conductivity measurements, microscopic analysis, X-ray diffraction (XRD) and ²⁹Si magic-angle spinning (MAS) nuclear magnetic resonance (NMR). In line with earlier observations, the analyses show that the highest amounts of amorphous silica occur in samples burnt in the range of 500 °C–700 °C. The ²⁹Si NMR data allow direct identification of the reactive silanol sites in the RHA samples. De-convolution of the NMR spectra clearly shows that the quickly cooled RHA resulting from burning rice husk for 12 h at 500 °C has the highest amount of silanol groups. This sample also induced the largest drop in conductivity when added to a saturated calcium hydroxide solution giving an indication of its reactivity towards lime. Therefore, this RHA is the favorable sample to be used as pozzolanic cement additive.     

Isoflavone content and apoptotic effect in HT-29 cancer cells of a soy germ extract

Colon cancer is one of the leading causes of death and a major public health problem in western countries. We examined the isoflavone content of 70% ethanol extract of soy germ (SG) and its apoptotic effect in HT-29 colon cancer cells. Our results showed that the major isoflavones of the SG extract were daidzein and genistein, and it effectively induced apoptosis in HT-29 cancer cells. In addition, nuclear factor-kappa B (NF-κB) expression was reduced in cells treated with the SG extract, which reduced cyclooxygenase-2 (COX-2) and nitric oxide synthase (iNOS) expression. These combined effects ultimately resulted in apoptosis via caspase-3 activation. In addition, daidzein and genistein, the major isoflavones of SG extract, also exerted the apoptotic effect against HT-29 cancer cells. These results suggest that the inhibition of NF-κB expression is the most important factor in the induction of apoptosis in HT-29 cells treated with the SG extract.