2007～2011年广西食用木薯淀粉微生物污染状况调查

介绍了广西近5年来食用木薯淀粉微生物污染状况,为质量监督工作和标准的制定工作提供依据。选用2007～2011年监督抽查和委托检验的190份食用木薯淀粉样品进行微生物学检测,按照不同年份、不同抽样方法、不同样品类别作分析比较。共检出超标样品63份,超标率为33.16%,带菌样品83份,带菌率为43.68%。不同年份超标率差异有统计学意义(P<0.005)。原淀粉和变性淀粉超标率分别为44.53%和5.66%,两者差异有统计学意义(P<0.005)。     

T-2毒素对不同生长期对虾的急性毒性及其分析方法的比较研究

比较T-2毒素对不同生长期凡纳滨对虾(Litopenaeus vannamei)的急性毒性及其分析方法,明确对虾作为T-2毒素毒性评价的生物标记物的最佳时期,建立T-2毒素对对虾的急性毒性互补评价方法。通过对不同生长期凡纳滨对虾的急性毒性试验,采用寇氏法和概率单位法,计算得到T-2毒素对不同生长期凡纳滨对虾的LD50,并通过u检验对两种方法求得的LD50值进行分析比较。结果得到T-2毒素对虾卵、幼虾和成虾的LD50值分别为2.33、1.79和3.34 mg/kg·bw,且经检验两种方法求得的LD50并无显著性差异。研究表明,T-2毒素对成虾的毒害作用最小急性毒性最弱,对幼虾的毒害作用最大急性毒性最强,即该生长期的凡纳滨对虾更适宜做评价T-2毒素急性毒性的生物标志物,同时采用寇氏法和概率单位法相结合的方法得到的LD50值更具准确。     

箱型梁附加挠度与剪力滞效应的一维有限元分析

当前箱型梁剪力滞效应分析的一维离散有限元法对剪力滞函数的处理存在局限性,而且剪力滞系数难以准确反映翼缘截面剪力滞效应及其变化规律。为此,利用箱梁附加挠度代替剪力滞函数建立箱梁翼缘的纵向位移函数,并根据能量变分原理建立控制微分方程并识别了其中的待定参数。以箱梁挠度、附加挠度及其一阶导数作为单元节点位移参数,提出了箱型梁剪力滞效应分析的一维离散有限元法,给出了箱梁的自然边界条件和强迫边界条件。基于箱梁挠度和附加挠度定义了新的剪力滞系数,分析了不同支撑条件对箱型梁剪力滞效应的影响。算例分析证明了该方法的有效性,且具有较高的计算精度;与传统的基于应力的剪力滞系数相比,基于挠度的剪力滞系数能够更加准确地反映箱型梁截面的剪力滞效应及其分布规律。     

基于专家-层次分析法的地质灾害风险性评价——以广西富川瑶族自治县为例

本文利用专家-层次分析法对地质灾害风险性进行评价,以广西贺州市富川瑶族自治县地质灾害风险调查评价为依托,通过资料分析和现场调研,根据各类地质灾害构建其风险性评价指标体系,采用专家-层次分析法对地质灾害风险性进行研究,研究结果表明：将富川瑶族自治县地质灾害风险分区分为高、中、低3种类型,富川瑶族自治县面积为1572.5 km²,其中地质灾害高风险区(I)的面积约为166.37 km²,约占研究区面积的10.58%;地质灾害中风险区(II)的面积为167.37 km²,约占研究区面积的10.64%;地质灾害低风险区(III)的面积约为1238.76 km²,约占研究区面积的78.78%。借助GIS平台实现可视化,评价结果对广西地区地质灾害的防治具有指导意义。     

2015-2020年广西毒蘑菇中毒事件流行病学分析

目的 分析广西毒蘑菇中毒事件流行病学特点,为毒蘑菇中毒的风险预警和预防控制提供科学依据。方法 采用描述流行病学方法,对广西2015—2020年食源性疾病事件监测系统报告的毒蘑菇中毒事件的流行病学特征进行分析。结果 2015—2020年,广西共报告毒蘑菇中毒事件189起,发病人数789人,死亡10人,病死率为1.27%。事件数最多的是2020年,占事件总数的38.10%(72/189);中毒事件主要发生在5～9月,高发地区为桂林市、百色市、梧州市和钦州市;家庭为主要的发生场所,占总事件数的93.65%(177/189),其中农村地区占88.14%(156/177);毒蘑菇中毒的主要原因为误食误用。结论 广西毒蘑菇中毒防控应根据高发季节、高危场所和人群有针对性行预防,加强对农村地区家庭的宣传教育,提高公众防范意识。     

电网企业基于不确定型电力电量平衡的购电成本分析

购电成本分析是电网企业的重要决策手段,而传统的购电成本分析一般是基于简单的确定型电力电量平衡,忽略了电力系统生产运行过程中所蕴涵的不确定性,使得分析结果无法提供全面的有价值的参考。文中首先根据模糊性及随机性的概念,利用序列运算理论从不同的角度对电力供需平衡中的不确定性进行描述,提出了不确定型电力电量平衡的新理念,并建立了其计算方法。由此对电网企业的购电成本进行分析,详细描述了购电成本分析的思想、方法和流程,并对电网企业的购电成本风险进行了评估。最后结合广西电网实际数据,对所提出的方法进行了实例说明以及有效性检验。     

Water uptake and pore volume determination of porous styrene–divinylbenzene copolymers

The relationship of water uptake and pore volume has been investigated for porous styrene–divinylbenzene (St–DVB) copolymers prepared in the presence of different inert diluents. It was found that the copolymers prepared in some conditions significantly increased their volume on taking up the water (swelling), and thus the use of water to measure the pore volume of porous St–DVB copolymers could hardly be recommended because the water uptake measurement does not always give a true value of the pore volume in dry state.     

Electromagnetic field intensity triggered micro-biopsy device for active locomotive capsule endoscope

For an active and precise diagnosis, we developed an active locomotive intestinal capsule endoscope (ALICE), which can be wirelessly driven and controlled using an electromagnetic actuation (EMA) system. Since then, there has been a need to develop a biopsy device integrated into ALICE which can take a biopsy sample inside the gastrointestinal tract for a historical analysis of cancer disease. Toward this goal, this paper proposes a smart-triggered biopsy device for the ALICE using a micro-reed switch, where the integrated micro-reed switch is turned on using a strong magnetic field, and the biopsy device mechanism is activated by a micro-reed switch. To execute the biopsy process, first, the ALICE with the biopsy device is driven by an EMA system, where a moderate intensity magnetic field is used for driving the ALICE to reach a target region on the intestinal wall. After that, by increasing the magnetic field above a critical value, the ALICE is pushed hard against the target lesion, the micro-reed switch is turned on, and the biopsy device is triggered. The biopsy process, therefore, is totally wirelessly controlled by the external magnetic field of the EMA system, without an additional controller module. The prototype of the biopsy device, with dimensions of 12 mm in diameter and 5 mm in length, was integrated into the ALICE and the prototype of the ALICE, with the biopsy device having dimensions of 12 mm in diameter and 32 mm in length. The working principle and mechanism of the proposed biopsy device are introduced and the feasibility of ALICE with the biopsy device is demonstrated through in-vitro experiments.     

Interphase precipitation of Fe2Hf Laves phase in a Fe–9Cr/Fe–9Cr–Hf diffusion couple

Periodically arrayed rows of fine Fe₂Hf Laves phase particles were found to form in ferritic matrix containing 9 weight percent chromium and a few weight percent hafnium. Microstructural investigation suggests that the particles were formed on cooling through interphase precipitation during the phase transformation from δ ferrite to austenite, and the austenite was subsequently transformed into the α ferrite. The interphase precipitation mode may be effectively used to strengthen ferritic heat resistant steels with Laves phase.     

Photocatalytic oxidation of methylene blue dye under visible light by Ni doped Ag2S nanoparticles

Ag₂S nanoparticles were prepared using a hydrothermal method, and Ni was doped via a photo-assisted deposition method. The samples produced were characterized using different tools. Furthermore, the catalytic performance of the Ag₂S and Ni/Ag₂S samples was examined in the degradation of methylene blue dye under visible light. The UV–vis spectral analysis detected a red shift after loading of Ni. The maximum degradation efficiency achieved was 100% with 3 wt% Ni/Ag₂S as the photocatalyst after a 40-min reaction time. The catalyst could be reused without any loss in activity for the first five cycles.