甜味糯米籺保鲜工艺研究

以糯米粉、粳米粉、黄糖等为主要原料,经模具成型、蒸煮、冷却、真空包装、杀菌等工序生产甜味糯米籺,分析蒸煮时间、冷却时间、杀菌温度与杀菌时间对甜味糯米籺保鲜效果及感官品质的影响。得出最佳工艺:蒸煮时间为1.5 h,冷却时间为20 min,杀菌温度为121℃,杀菌时间为15min。检测得甜味糯米籺真空包装冷藏(5~8℃)120 d,菌落总数为1 300 cfu/g,大肠菌群数为3MPN/g;真空包装冻藏(低于-12℃)180 d,菌落总数1 200 cfu/g,大肠菌群3 MPN/g;致病菌均未检出。糯米籺外观色泽较好,试吃后口感、风味仍优。甜味糯米籺在真空包装下冷藏(5~8℃)可储藏120 d,冻藏(低于-12℃)可储藏180 d。     

某工程基础及钢围堰设计与施工

水中基础施工是桥梁施工中控制工期的重要节点,该文阐述了在枯水期通过先旋挖钻孔施工桩基础再进行钢围堰施工,可避免常规施工方法在钢围堰上搭设钻孔平台进行水上钻孔施工的安全风险,为类似工程提供一定的参考。     

Effect of working position and cold environment on muscle activation level and fatigue in the upper limb during manual work tasks

Several occupational groups are exposed to periods of low ambient temperatures while performing manual work tasks outdoors. Work tasks typically include heavy lifting, tool handling, and overhead work. This study evaluated the effect of working position and cold environment on muscle activation level (%RMS_max) and fatigue in the upper limb during manual work tasks. Fourteen male participants (25 ± 3 years, 80.9 ± 6.4 kg, 182 ± 5 cm) completed a 2-h test protocol consisting of five test periods alternating with four work periods, wearing identical sets of clothing, under cold (−15 °C) and control (5 °C) conditions. The work periods consisted of manual work at the hip level, manual overhead work, and a lifting exercise. The test periods consisted of isometric maximal voluntary contractions (MVC) and seated rest. Skin temperatures decreased during cold exposure, especially in the extremities. %RMS_max in the forearm was higher in the cold condition both during overhead work and work at the hip level than that for the same work in the control condition, especially at the end of the test when the difference was approximately 25% (equating to 2–3 %RMS_max). For the middle deltoid muscle, the %RMS_max was approximately three times (or 10 %RMS_max) higher during overhead work than work at the hip level, but there was no additional cost of working in the cold. Signs of deltoid muscle fatigue (decrease in electromyography median power frequency and an increase in %RMS_max) were observed during the overhead work periods in both temperature conditions. No decrease in MVC, as a sign of overall muscle fatigue, was observed in either condition.Relevance to industryThis study demonstrated that when wearing suitable cold-weather protective clothing, the adverse effect of work posture is much higher than that of cold on muscle demand and physical strain.     

Experimental investigation of the drying characteristics of a mixed mode natural convection solar crop dryer with back up heater

A mixed mode natural convection solar crop dryer with a backup heater was designed and constructed from locally available materials and used to dry freshly prepared pineapples under four drying Scenarios for drying to correspond to specified drying periods for four typical seasons in Ghana. The experiments were devised for the material moisture content to be monitored continuously till the desired moisture content of between +106% and 184% (d.b) was achieved. In solar heating mode of operation, results show that the thermal mass was capable of storing part of the absorbed solar energy but the quantities involved are insufficient to sustain night drying. It was possible to dry a batch of pineapples in each mode of operation. The dryer reduced the moisture content of pineapple slices from about; 924% to 106% in 19 h; 1049% to 184% in 10 h; 912% to 155% in 7 h; and 1049% to 144% (d.b) in 23 h, for drying in Scenarios 1, 2, 3 and 4, respectively. The average moisture pickup efficiency values obtained were 27%, 24%, 11%, and 32% for drying in Scenarios 1, 2, 3, and 4, respectively.     

Plasma albumin-to-globulin ratio before dry-off as a possible index of inflammatory status and performance in the subsequent lactation in dairy cows

The dry-off of dairy cows represents an important phase of the lactation cycle, influencing the outcome of the next lactation. Among the physiological changes, the severity of the inflammatory response can vary after the dry-off, and this response might have consequences on cow adaptation in the transition period. The plasma protein profile is a diagnostic tool widely used in humans and animals to assess the inflammatory status and predict the outcome of severe diseases. The albumin-to-globulin ratio (AG) can represent a simple and useful proxy for the inflammatory condition. In this study, we investigated the relationship between AG before dry-off and inflammation, metabolic profile, and performance of 75 Holstein dairy cows. Blood samples were collected from ?62 (7 d before dry-off) to 28 d relative to calving (DFC) to measure metabolic profile biomarkers, inflammatory variables, and liver function. Daily milk yield in the first month of lactation was recorded. Milk composition, body condition score, fertility, and health status were also assessed. The AG calculated 1 wk before dry-off (?62 DFC) was used to retrospectively group cows into tertiles (1.06 ± 0.09 for HI, 0.88 ± 0.04 for IN, and 0.72 ± 0.08 for LO). Data were subjected to ANOVA using the PROC MIXED program in SAS software. Differences among groups observed at ?62 DFC were almost maintained throughout the period of interest, but AG peaked before calving. According to the level of acute-phase proteins (haptoglobin, ceruloplasmin, albumin, cholesterol, retinol-binding protein), bilirubin, and paraoxonase, a generally overall lower inflammatory condition was found in HI and IN than in the LO group immediately after the dry-off but also after calving. The HI cows had greater milk yield than LO cows, but no differences were observed in milk composition. The somatic cell count reflected the AG ratio trend, with higher values in LO than IN and HI either before dry-off or after calving. Fertility was better in HI cows, with fewer days open and services per pregnancy than IN and LO cows. Overall, cows with high AG before dry-off showed an improved adaptation to the new lactation, as demonstrated by a reduced systemic inflammatory response and increased milk yield than cows with low AG. In conclusion, the AG ratio before dry-off might represent a rapid and useful proxy to evaluate the innate immune status and likely the ability to adapt while switching from the late lactation to the nonlactating phase and during the transition period with emphasis on early lactation.     

高密度聚乙烯装置循环气冷却器腐蚀原因分析及防护

针对高密度聚乙烯装置循环气冷却器在使用中存在的腐蚀问题进行分析。通过采用相应的防护办法,取得良好的效果。     

岩石冻融循环试验建议性方案探讨

岩石冻融循环试验是低温岩石力学基础性试验,其主要涉及冻融循环温度、冻融时长、循环次数等3个指标。但目前关于指标的选取,国内外的试验规程或相关学者研究成果,均未给出明确参考依据,对岩石冻融循环试验方案的确定造成较大困扰。本研究旨在明确各指标的确定办法,提出建议性岩石冻融循环试验方案。首先,展开国内外冻融循环试验方案的全面综述,指出目前冻融循环试验方案确定时所存在问题,并藉此明确冻融循环试验方案思路;接着,针对以上三大影响指标,通过设计室内岩石冻融循环试验,详细探讨冻融循环温度、冻融时长、循环次数对岩石物理、力学参数的影响,最终根据试验结果,明确出针对不同岩性、孔隙率所对应的建议性试验方案。本研究将为后期冻融循环指标选取及标准化试验方案建立提供技术借鉴。     

Evolution of Oxidative Values during Kinetic Studies on Olive Oil Oxidation in the Rancimat Test

A comparative study was carried out in order to evaluate the kinetics of the formation of a number of primary and secondary oxidation products during oxidation of olive oil in the Rancimat test at 100–130 °C. There were good correlations between the Rancimat index (OSI) and stability indices (IP) measured in the Rancimat test with no significant differences in kinetic parameters calculated from them. Mean values of the temperature coefficient, Q₁₀ number, activation energy (E_a), frequency factor (A), and free energy of activation (ΔG⁺⁺) for olive oil oxidation were calculated to be ?3.44 × 10^?2°C^?1, 2.21, 98.91 kJ/mol, 12.17 × 10¹² h^?1, and 128.25 kJ/mol, respectively. Each unit change in E_a was accompanied by an average 1.43 × 10¹² change in A, indicating a higher contribution for factor A than for E_a to the olive oil stability. The E_a and A correlated well with the values of enthalpy and entropy, respectively. The values of OSI or IP could be described well by the ΔG⁺⁺ values. Kinetic data indicated that olive oil stability is more affected by the indigenous antioxidants than by the fatty acid composition.