合肥市即食肉类食品中金黄色葡萄球菌污染情况及耐药和基因型分布

目的调查合肥市即食肉类食品中金黄色葡萄球菌的污染情况,并对分离株进行耐药性分析及多位点序列分型研究。方法 2017年10月—2018年10月自合肥市区范围内的超市和开放型菜市场共采集744份即食型肉类食品样品。根据GB 4789.10—2016《食品安全国家标准食品微生物学检验金黄色葡萄球菌检验》中的方法对样品进行金黄色葡萄球菌定性和定量分析,采用K-B纸片扩散法检测分离株的耐药性,采用多位点序列分型法对分离株进行ST分型,使用MEGA 7.0绘制聚类树状图。结果样品中金黄色葡萄球菌检出率为4.2%(31/744),其中卤肉制品检出率最高为8.1%(15/185),其次为烤肉制品(6.3%,11/174),定量分析显示超过90%的样品金黄色葡萄球菌污染水平在0.3～10 MPN/g范围内。耐药性分析结果显示80.6%(25/31)的菌株对青霉素G耐药,40%以上的菌株对链霉素、红霉素和卡那霉素耐药;多重耐药菌株占比为61.3%(19/31)。分型分析共获得8个ST型,分别为ST6、ST7、ST15、ST59、ST72、ST188、ST398和ST2196型,其中以ST188和ST72型为主。结论合肥市卤肉和烤肉制品中存在金黄色葡萄球菌污染,且多重耐药菌株比例较高,对消费者的健康有潜在威胁,有必要持续监测污染率、菌株耐药和基因型流行趋势,完善合肥市食源性金黄色葡萄球菌感染的风险评估。     

快速计算工字轮及缠绕物参数的方法

根据生产情况,对工字轮中的钢丝绳和钢丝分别建立数学模型,通过对数学模型的分析,利用Excel表格,快速获得卷装物的长度或工字轮的参数和容重。计算结果与生产实际情况较好地吻合,满足生产需求。     

A field-portable thermal infrared grating spectrometer (THIRSPEC)

A thermal infrared grating spectrometer was developed for field studies in the Earth sciences. The design is based on a reflection grating and a 60-element HgCdTe detector array. The useful spectral range of the instrument covers 7.9-11.3 μm with a Nyquist limited resolution of 0.16 μm. The instrument averages over a 12° field of view and compares the exitance of the target to that of an internal black body at ambient temperature. The noise equivalent temperature is approximately 0.06°K over the useful spectral range. Background radiance reflected from the surface of the target can seriously impede the determination of emissivity. This effect is removed from the spectra of geological samples by the use of reference samples     

Modulation of Mechanical Interactions by Local Piezoelectric Effects

Piezoelectricity is a well‐established property of biological materials, yet its functional role has remained unclear. Here, a mechanical effect of piezoelectric domains resulting from collagen fibril organisation is demonstrated, and its role in tissue function and application to material design is described. Using a combination of scanning probe and nonlinear optical microscopy, a hierarchical structuring of piezoelectric domains in collagen‐rich tissues is observed, and their mechanical effects are explored in silico. Local electrostatic attraction and repulsion due to shear piezoelectricity in these domains modulate fibril interactions from the tens of nanometre (single fibril interactions) to the tens of micron (fibre interactions) level, analogous to modulated friction effects. The manipulation of domain size and organisation thus provides a capacity to tune energy storage, dissipation, stiffness, and damage resistance.     

Reduction of ASR-expansion using powders ground from various sources of reactive aggregates

This study assesses the potential of ground reactive aggregates to reduce or suppress expansion associated with ASR. Particular attention is paid to fine admixtures (<80 μm) added to mortars, which contain the reactive aggregates from which the fines were ground. Many varieties of aggregate (quarried and natural, igneous, metamorphic and sedimentary rocks) from different geological settings were subjected to an autoclave test. The replacement of 10–20% of the sand by reactive aggregate powder (RAP) of different surface areas from 11 different reactive aggregates led to the reduction of ASR-expansion by up to 78% compared with control mortars. Increasing the amount of fines led to better performance. No clear relationship was observed between the reactivity degree of the aggregates and the efficiency of their ground powder to reduce expansion. A general trend was found regarding the fineness of ground aggregates: finer particles were more effective in reducing expansion. The reduction of the expansion due to RAP is discussed in terms of parameters affecting its efficiency and of the mechanisms responsible for the reduction.     

Floor shape optimization for green building design

Shape is an important consideration in green building design due to its significant impact on energy performance and construction costs. This paper presents a methodology to optimize building shapes in plan using the genetic algorithm. The building footprint is represented by a multi-sided polygon. Different geometrical representations for a polygon are considered and evaluated in terms of their potential problems such as epistasis, which occurs when one gene pair masks or modifies the expression of other gene pairs, and encoding isomorphism, which occurs when chromosomes with different binary strings map to the same solution in the design space. Two alternative representations are compared in terms of their impact on computational effectiveness and efficiency. An optimization model is established considering the shape-related variables and several other envelope-related design variables such as window ratios and overhangs. Life-cycle cost and life-cycle environmental impact are the two objective functions used to evaluate the performance of a green building design. A case study is presented where the shape of a typical floor of an office building defined by a pentagon is optimized with a multi-objective genetic algorithm.     

Estimated potassium content in Hanford workers

Potassium content in male and female workers at the US Department of Energy Hanford Site was estimated based on measurements made in 2002 of 40K activity in the body. The 40K activity in females ranged from 2.1 to 4.1 kBq with an average of 3.1 +/- 0.02 kBq. The total body potassium (TBK) content in females averaged 98 +/- 0.6 g. The 40K activity in males ranged from 2.8 to 6.6 kBq with an average of 4.2 +/- 0.01 kBq and the average TBK was 136 +/- 0.3 g. The average TBK value for males aged 20-49 y was 140 g. The average TBK values for both genders decreased with age. The average potassium concentrations calculated for the different age ranges for males were 15-25% less than the value (1.9 gK per kg) obtained using the reported ICRP reference potassium and reference weight values. Potassium concentrations were inversely correlated with body-build index, body-mass index and body weight. These correlations could possibly be utilised to help assess the risk for disease. Future work is planned to evaluate whether monitoring of potassium concentrations could be used as a tool for the detection of diabetes and hypertension.     

用谱仪测量环境 Υ 照射量率

本文介绍了一台就地测量环境γ照射量率的 NaI(Tl)谱仪。并介绍了测量陆地总γ照射量率的谱能法和测量单个核素或天然衰变系γ照射量率的峰面积法及其有关刻度因子与参数的确定方法。在原子能所建筑物内外做了一些现场测量,有的测量结果和高压电离室或 PTB-7201型剂量仪的测量值作了比较,二者在±5%范围内是吻合的。     

关于用FD-71型闪烁辐射仪测量环境γ照射量率的讨沦

本文讨论了 FD-71型闪烁辐射仪用于环境γ照射量率测定时的能响修正、环境因素影响和探测限等问题。FD-71受环境温度影响不大;但能响很差,若不修正,可引起+50%至+150%的误差,采用典型环境γ场刻度修正系数修正后,由能响引起的不确定度仍可达±25%;最小可探测限约为1μR/h。