Discrimination the geographical origin of Yanchi Tan Lamb with different muscle sections by stable isotopic ratios and elemental profiles

In the study, lamb, feed and soil samples were collected from three regions of China in the year 2017 and 2018. The δ¹³C and δ¹⁵N values in lamb (defatted dry mass and lipids) and grass and the contents of nine elements in lamb, grass and soil were determined. The results indicated that except for Fe, Zn and Rb, most variables of lamb showed significant differences among two or three regions, and the contents of Fe, Sr and Cs showed significant differences between two years, and the contents of Cu and Zn showed significant differences among different muscle sections. Besides, significant correlations were found for δ¹³C between defatted lamb and lipid (r² = 0.973, P < 0.05) and for the element contents between lamb and soil. Finally, four key variables δ¹³C, δ¹⁵N, Sr and Mo were selected through stepwise canonical discriminant analysis with the cross-validation correct classification rate of 99.1%.     

HFETR碘坑后沿启堆临界棒位的估算

本文研究高通量工程试验堆(HFETR)在碘坑内启动反应堆的问题。首先根据反应堆在碘坑内启堆时碘(135I)和氙(135Xe)浓度随时间变化关系推导出了氙毒引入的反应性随时间变化的解析表达式;接着针对HFETR某炉段进行研究,并结合冷却剂温度效应、燃耗及停堆前的棒位,给出估算碘坑后沿启动反应堆的临界棒位的方法;最后基于MATLAB软件开发用于估算碘坑后沿启动反应堆的临界棒位的程序。     

Effects of different agro-industrial waste as substrates on proximate composition,metals, and mineral contents of oyster mushroom (Pleurotus ostreatus)

The use of agro-industrial waste as substrates for mushroom cultivation is considered a promising management strategy for reducing and valorising these wastes, simultaneously reducing the cost of mushroom cultivation. In this study, oyster mushroom Pleurotus ostreatus were cultivated on twelve substrates composed of either tea waste, lime sawdust, alder sawdust, hornbeam sawdust/shaving, wheat stalk-straw, wheat bran or their composite to determine the proximate composition and accumulation of thirteen elements in their fruiting bodies. The proximate composition of P. ostreatus did not show a significant difference, regardless of the employed substrate. (one-way manova ; F_{(66, 107)} = 1.329, Wilk’s λ = 0.041, P > 0.05). However, their chemical element contents show a statistically significant difference (one-way manova ; F_{(132, 418)} = 32.163, Wilk’s λ = 0.000, P < 0.05). These results were supported by discriminant function and principal component analyses. The highest mean concentrations of six of twelve elements (i.e., Ca, Mg, Na, Zn, Cd and Cr) were recorded in P. ostreatus cultivated on the lime-sawdust substrate. Three health indices viz., estimated daily intake, target hazard quotient (THQ) and total THQ were applied to determine the risk to human health via the consumption of P. ostreatus, suggesting that they are safe for human consumption.     

碳酸盐矿石中钨的前处理方法研究

对碳酸盐矿石中钨的熔矿方法进行了研究,分别考察了坩埚、熔剂、双氧水等因素的影响,通过电感耦合等离子体发射光谱法和传统比色法对钨含量的测定结果比较,得出以镍坩埚、氢氧化钠对碳酸盐矿石进行熔矿前处理,钨能较多的存在于溶液中以利于含量的测定。     

WF油田强底水断块油藏开发规律研究及认识

为改善底水油藏开发效果,结合WF油田强底水断块油藏历年开发实践的基础上,分别对不同开发阶段的影响因素进行了详细分析,总结了强底水断块油藏的开发规律。通过计算临界产量和统计生产初期打开程度与含水的关系,早期应充分利用天然隔板,合理打开程度在30%左右;中期含水20%~80%时,合理控制生产压差;后期提掖稳产,晚期上返挖潜,确保了底水油藏的有效开发。该方法从不同生产阶段来分别制定对策,能充分挖掘油藏的生产潜力,来提高开发效果,其做法及经验可供同类型油藏开发参考借鉴。     

不同方法测定两种表面活性剂的临界胶束浓度

采用电导法及表面张力法分别测定了十二烷基硫酸钠(阴离子表面活性剂)和十二烷基三甲基氯化铵(阳离子表面活性剂)的临界胶束浓度,两种实验方法测得十二烷基硫酸钠的临界胶束浓度约为7.0×10-3mol·dm-3,十二烷基三甲基氯化铵的临界胶束浓度约为1.60×10-2mol·dm-3,两种方法所得结果一致。     

原子荧光仪测试岩石矿物中硒元素试验研究

探讨了原子荧光仪测试岩石矿物中硒元素试验研究。运用原子荧光仪测试岩石矿物中硒元素,结果显示：原子荧光仪测试岩石矿物中方法硒元素的回收率、相对标准偏差、方法检出限分别为98.2%-103.0%、0.95%-5.80%、3.5×10^-11g/m L。原子荧光仪方法测试岩石矿物中硒元素具有较为快捷的速度、较高的灵敏度,且简便易行等,值得推广。     

基于分离效率的卧螺离心机CFD分析

从分离效率的角度对卧式螺旋卸料离心机转鼓内的流场进行数值分析.通过剖析推料螺旋与转鼓溢流堰的结构特点可知,转鼓内流体在轴向为薄层流动,在径向由于涡流产生向内流动导致颗粒上浮,这两者对离心机分离效率有决定性的影响.结合CFD数值分析和颗粒的Stokes沉降运动关系,提出将薄层流动与上浮临界粒度应用于离心机分离能力计算的理论和方法.文章通过定义沉降粒度和上浮临界粒度,进一步把分离能力计算与分离效率相关联,使该方法更接近离心机分离工艺的实际情况.通过对工业中典型离心机进行实例计算,证明了该方法的可行性和准确性.     

活性粉末混凝土中带肋钢筋搭接性能试验研究#br#

为明确活性粉末混凝土RPC（reactive powder concrete）中带肋钢筋搭接连接的受力性能,合理确定RPC中纵筋的搭接长度,以纵筋搭接长度、RPC强度、搭接钢筋净距和配箍率为试验参数,对39个RPC中的钢筋搭接连接试件进行对拉试验,获得各试验参数对RPC中带肋钢筋搭接连接性能的影响规律。结果表明：对拉荷载作用下,RPC中带肋钢筋搭接连接分别出现钢筋拔出和拉断两种破坏模式,对于保护层厚度小于2倍钢筋直径的拔出破坏试件,一般还伴随外围RPC劈裂裂缝的出现;对于拔出破坏试件,搭接区域的搭接强度随搭接长度增大而略有减小、随RPC强度和配箍率的增加而增大;相较于搭接长度为100mm的试件,搭接长度为150mm试件的搭接强度约减小5%;强度等级为100MPa、120MPa和150MPa的RPC与直径为20mm带肋钢筋间的搭接强度分别约为17.5MPa、19.5MPa和21.1MPa;相较于未配箍筋试件,配箍率为0.34%和0.75%试件的搭接强度分别提高7.8%和13.1%;相较于钢筋净距为20mm试件,净距为0和40mm试件的搭接强度分别约减小5%和8%,但净距40mm试件搭接强度的降低主要是由于试件RPC保护层厚度过小,使得钢筋外围RPC产生劈裂所致。根据试验结果,建立搭接区域钢筋表面搭接强度及临界搭接长度的计算公式,并以该文及其他研究者的试验结果验证了所提公式的适用性,据此可确定带肋钢筋在RPC中的临界搭接长度。