红外辐射联合回火与冷激杀菌技术对胡萝卜粉品质的影响

首先研究不同红外辐射温度(100,110,120℃)及辐射时间(2.5,5,10 min)对胡萝卜粉微生物及品质的影响,然后根据栅栏效应原理研究红外辐射-回火、红外辐射-冷激联合杀菌对胡萝卜粉微生物、色调值、类胡萝卜素含量等品质的影响。结果表明:100℃、10 min的红外辐射处理使细菌和真菌分别降低了1.9 lg(CFU/g)和2.32 lg(CFU/g),110℃、5 min的红外辐射处使细菌和真菌分别降低了1.58 lg(CFU/g)和2.57 lg(CFU/g)。在上述两种处理条件下胡萝卜粉的水分活度从0.238分别降至0.123和0.147,胡萝卜粉中总类胡萝卜素含量从308.8μg/g降至227.8μg/g和238.8μg/g,色差值(ΔE)为9.11和7.89。与红外辐射单独作用相比,联合回火后的处理没有显著影响细菌数目,处理后保持在5.40~5.80 CFU/g,霉菌、酵母数却在处理过程中显著减少,然而减少量较低,总数仍不低于4.5 lg(CFU/g)。红外辐射-冷激联合处理相比红外辐射单独处理,100℃、10 min联合冷激7 d处理可将细菌数量降低0.25 lg(CFU/g),可将霉菌与酵母数量降低0.28 lg(CFU/g),110℃、5 min联合冷激7 d处可将细菌数量降低0.26 lg(CFU/g),可将霉菌、酵母数量降低0.40 lg(CFU/g),且这些处理下胡萝卜粉的色调值、水分活度、类胡萝卜素含量变化不显著。本试验结果表明,红外辐射-冷激处理具有协同效应,且处理过程中胡萝卜粉的色调值及总类胡萝卜素含量不受影响,这为低水分粉体食品红外辐射联合杀菌提供了参考。     

As the number falls,alternatives to the Hagberg–Perten falling number method: A review

This review examines the application, limitations, and potential alternatives to the Hagberg–Perten falling number (FN) method used in the global wheat industry for detecting the risk of poor end-product quality mainly due to starch degradation by the enzyme α-amylase. By viscometry, the FN test indirectly detects the presence of α-amylase, the primary enzyme that digests starch. Elevated α-amylase results in low FN and damages wheat product quality resulting in cakes that fall, and sticky bread and noodles. Low FN can occur from preharvest sprouting (PHS) and late maturity α-amylase (LMA). Moist or rainy conditions before harvest cause PHS on the mother plant. Continuously cool or fluctuating temperatures during the grain filling stage cause LMA. Due to the expression of additional hydrolytic enzymes, PHS has a stronger negative impact than LMA. Wheat grain with low FN/high α-amylase results in serious losses for farmers, traders, millers, and bakers worldwide. Although blending of low FN grain with sound wheat may be used as a means of moving affected grain through the marketplace, care must be taken to avoid grain lots from falling below contract-specified FN. A large amount of sound wheat can be ruined if mixed with a small amount of sprouted wheat. The FN method is widely employed to detect α-amylase after harvest. However, it has several limitations, including sampling variability, high cost, labor intensiveness, the destructive nature of the test, and an inability to differentiate between LMA and PHS. Faster, cheaper, and more accurate alternatives could improve breeding for resistance to PHS and LMA and could preserve the value of wheat grain by avoiding inadvertent mixing of high- and low-FN grain by enabling testing at more stages of the value stream including at harvest, delivery, transport, storage, and milling. Alternatives to the FN method explored here include the Rapid Visco Analyzer, enzyme assays, immunoassays, near-infrared spectroscopy, and hyperspectral imaging.     

Optimization of room-temperature TCR of polycrystalline La0.9-xSrxK0.1MnO3 ceramics by Sr adjustment

High-density La_0.9-xSr_xK_0.1MnO₃ ceramics (LSKMO, A-site = La, Sr and K, 0 ≤ x ≤ 0.25) are successfully fabricated by using facile sol-gel method. Electrical properties are performed by using combination of phenomenological percolation (PP) model, double exchange (DE) mechanism, and Jahn-Teller (JT) effect. Moreover, X-ray diffraction and scanning electron microscopy are employed to analyze the structure and morphology of LSKMO ceramics. Valence states and ionic stoichiometry are assessed by using X-ray photoemission spectrometry. Results reveal that Sr²⁺ ions, substituting La³⁺ ions, significantly influenced DE mechanism and JT effect. In addition, Sr-doping plays essential role in improving electrical properties of LSKMO ceramics. At optimal doping content of x = 0.09, peak temperature coefficient of resistance (TCR) of the resistivity is found to be 11.56% K^?1 at 297.15 K, which is optimal TCR for A-site K-occupied perovskite manganese oxides. These results confirm that polycrystalline LSKMO ceramics render high room-temperature TCR values due to Sr-doping.     

Growth mechanism and gas-sensing characteristics of organic-additive-free zinc oxide of various shapes

Zinc oxide is widely used in gas sensors, solar cells, and photocatalysts because of its wide bandgap and exciton binding energy of 60 meV in various metal oxides. To use ZnO as a gas sensor, it is necessary to synthesize it with surface defects and a large specific surface area. In this study, hydrothermal synthesis without surfactants was employed to obtain organic-additive-free ZnO. For morphology control, we varied the ratio of the hydroxide ion concentration to the zinc ion concentration. To confirm the growth mechanism of ZnO, we performed X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses. Raman spectroscopy and photoluminescence measurements were performed to analyze the surface properties. The Brunauer–Emmett–Teller method and probe stations were used to measure the specific surface area and sensitivity of the gas sensor, respectively. The results confirmed that flower-shaped ZnO is the most suitable gas-sensing material.     

物料堆场智能化管理经验分享

华润水泥（罗定）有限公司根据物料储存需求，共有三个长堆棚分为9个室内料场堆放原材料及混合材，厂内有4台铲车无规则轮流在这8个料场内作业，同时外来运料货车、公司化验及验收人员也会不间断地进入不同堆棚。由于料场内空间狭窄，驾驶员视线不好，如果堆棚料场内铲车在作业时，有其他人员或车辆进入铲车工作区域共同作业，在没有检测装置对进入的人、车进行识别，提醒铲车驾驶员的情况下，容易发生碾压进入人员或车辆碰撞的安全事故。公司根据现场实际，自2020年起决定实施从堆场出入口智能红外感应技术、装载机车载识别系统、智能声光语音提醒、实时监控显示、照明、堆场硬件设施等五方面实施物料堆场车辆智能化安全预警系统项目。     

Elemental analysis of cemented carbides by calibration-free portable laser-induced breakdown spectroscopy

The process of cemented carbides manufacturing requires rapid and field elemental analytical techniques to control and evaluate the properties of products. Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) is such a potential elemental analytical technique. In this work, a portable LIBS instrument combined with a CF method was developed for the analysis of cemented carbides. Three batches of cemented compact carbides without reference samples were analyzed. Qualitative and quantitative analysis of the samples were achieved by using the portable LIBS instrument combined with CF method. To validate the analysis results, X-ray fluorescence spectrometry (XRF) was used to analyze the samples as well. The results of CF-LIBS agreed well with the results of XRF, with relative errors between ?29.53 and 24.70%. The results demonstrated that the portable LIBS instrument combined with CF method was capable for direct and rapid analysis without any need of standard measurements. Notably, with the portable LIBS instrument combined with CF method, acceptable accuracy could be obtained, which is promising for practical field applications.     

红外菲涅尔透镜的注射超声辅助成型优化

为了提升聚合物红外菲涅尔透镜的光学性能,以其表面微沟槽的成型质量为目标,提出了一种高效的注射超声辅助成型方法,并对工艺参数进行了综合质量优化。首先分析了超声振动对聚合物的加热和加压效应,设计了一套一模两腔的对比试验模具;接着以红外菲涅尔透镜的调制传递函数MTF和齿形平均高度h为优化质量目标,设计了四步骤的多目标优化流程,通过试验设计、基于BP神经网络的质量目标与注射工艺参数关系建模、基于NSGA-Ⅱ的多目标优化和试验验证进行工艺参数的综合优化。实验结果表明:该多目标优化流程具有很高的精度,MTF和h的平均预测误差MPE分别为4.16%和3.32%;注射超声辅助成型的菲涅尔透镜微沟槽具有更高的复制质量,其齿沟槽平均高度h增加了15.6%,且h值的波动量随着h值的增大而增大,MTF值受齿高h均匀性的影响大于齿高h对其的影响。     

临近空间载人舱舱门密封特性研究

为研究临近空间载人舱舱门密封特性,对临近空间载人舱舱门P形橡胶密封圈进行有限元压缩行为仿真分析,分析P形橡胶密封圈主副密封面密封接触宽度和接触应力随舱门间隙与舱门行程变化的规律,并根据该规律给出舱门压缩行程和舱门密封间隙的设计推荐值。基于ROTH泄漏模型推导出P形橡胶密封圈的总漏率模型,并计算该泄漏模型的稳态漏率值。通过舱门密封试验,对P形橡胶密封圈的总漏率进行验证。P形橡胶密封圈总漏率计算值与试验结果基本吻合,验证了P形橡胶密封圈总漏率模型的有效性。