浓香大豆油制备工艺研究

以黑龙江省非转基因大豆为原料,通过单因素试验对浓香大豆油的风味进行了研究,得到产生浓香型大豆油的最佳工艺条件:热炒豆占原料比例30%,热炒温度180℃。在保证浓香风味的基础上,以出油率为指标,通过单因素试验和正交试验对浓香大豆油的压榨工艺进行研究,得到最佳压榨条件为:压榨压力4MPa,压榨温度130℃,物料总水分4%,出油率达到57.1%。此条件下得到的大豆油气味浓郁,透明澄清,符合国家四级大豆油标准。     

漏磁腐蚀检测器新型探头机构的设计

为了解决漏磁腐蚀检测器在管道内检测过程中因探头机构姿态不稳、偏磨及支撑弹簧易折断、易震颤带来的一系列问题,对检测器所用探头机构进行研究,设计制造了一种全新的探头机构.该机构增加了辅助支撑弹簧和柔性连接铰链,很好地解决了传统探头机构存在的不足.该机构的检测探头将以往探头加耐磨层结构变为整体灌装探头壳形式,改善了检测探头的提离值,提高了检测信号的可靠性.与传统探头机构相比,该机构的使用能够有效提高检测数据的可靠性和稳定性.     

《热学》省级精品课程建设的探索与实践——以四川文理学院为例

精品课程建设是从根本上提高高等教育质量和人才培养质量的奠基性工作.四川文理学院《热学》省级精品课程在建设实践中,明确提出了＂为学生而建＂的课程建设目的;紧紧围绕学院的办学定位、人才培养定位以及物理学本科专业的人才培养目标,理清了课程建设的思路;重点开展了师资队伍建设、教学方法改革、教材建设等建设工作;同时,还建立了有效的激励机制、多样的交流机制和综合的评价机制,有力地保障和提升了精品课程的建设水平.     

Comparison of heat tolerance of feedlot heifers of different breeds

Heat stress in cattle causes decreases in feed intake and feed efficiency; in extreme cases, it can cause death. These losses amount to millions of dollars each year. A study was designed to determine severity of heat stress among four breeds of cattle. Throughout two summers, 256 feedlot heifers of four different breeds were observed. Respiration rates, panting scores, and surface temperatures were taken twice each day on 10 animals/breed for several weeks during the summers of 2002 and 2003. Twenty-four-hour behavior measurements were recorded for four heat-stress and four thermoneutral days. Results showed during the afternoon, Angus cattle (black) had the highest respiration rates, panting scores, and surface temperatures, followed by the MARC III (dark red), Gelbvieh (tan), and Charolais (white). Behavior data showed that heat stress increased drinking and standing behavior, and decreased eating, lying, and agonistic behaviors, and that dark-hided cattle adjusted their behavior more than light-hided cattle. Overall, it was found that breed of cattle with dark-hides were more affected by temperature changes and at peak temperatures than breeds of cattle with light-hides.     

Heat stress risk factors of feedlot heifers

Heat stress in cattle results in millions of dollars in lost revenue each year due to production losses, and in extreme cases, death. Death losses are more likely to result from animals vulnerable to heat stress. A study was conducted to determine risk factors for heat stress in feedlot heifers. Over two consecutive summers, a total of 256 feedlot heifers (32/ breed/ year) of four breeds were observed. As a measure of stress, respiration rates and panting scores were taken twice daily (morning and afternoon) on a random sample of 10 heifers/ breed. Weights, condition scores, and temperament scores were taken on 28-day intervals during the experiment. Health history from birth to slaughter was available for every animal used in this study. It was found that at temperatures above 25 °C, dark-hided animals were 25% more stressed than light-colored; a history of respiratory pneumonia increased stress level by 10.5%; each level of fatness increased stress level by approximately 10%; and excitable animals had a 3.2% higher stress level than calm animals. Not only did the stress level increase with these risk factors, but average daily gain was reduced. The Charolais cattle gained significantly more than all other breeds of cattle tested. Calm cattle gained 5% more than excitable cattle. Finally, cattle treated for pneumonia gained approximately 8% slower than non-treated cattle. The results of this study have not only revealed heat stress risk factors of breed (color), condition score (fatness), temperament, and health history (treated or not treated for pneumonia), but have also shown the effectiveness of using respiration rate as an indicator of heat stress.     

Effects of chilled drinking water on the performance of lactating sows and their litters during high ambient temperatures under farm conditions

Heat stress has detrimental effects on lactating sows and their litters, including decreased feed intake and milk production in sows and decreased weight gain in their offspring. It also increases respiration rate, rectal temperature, and weaning to estrus interval in sows. This study was conducted to investigate the effects of chilled water (CW) on the performance of lactating sows and their litters exposed to high ambient temperatures for 21 days. Ninety multiparous sows (Yorkshire × Landrace; parity range: 2 to 5) and their litters (Yorkshire × Landrace × Duroc) were divided into 3 blocks (30 each). Sows and their litters within each block were randomly assigned to one of the three treatment groups (n = 10 each). Each group was provided with drinking water at 10, 15, or 22 °C (control) under farm conditions where ambient temperature above 25 °C was consistent during the experimental period. Sows on CW (both 10 and 15 °C) consumed more feed and water than did control (P < 0.01) and higher estimated milk production compared with control (P < 0.01), but had lower rectal temperature and respiration rate compared with control (P < 0.01). Mean weaning weight (P < 0.01) and average daily gain (P < 0.01) of litters in CW groups were higher than those in control group. There were no differences in the measured variables, with the exception of the respiration rates, between the two CW treatment groups. These results suggest that CW may improve the performance of sows and their litters exposed to high ambient temperatures and the 15 °C water, from an energy viewpoint, may be more effective.     

Utility of on- and off-farm weather records for studies in genetics of heat tolerance

Utility of weather information from on-farm and weather stations was evaluated for the application in studies on the genetics of heat stress. Daily milk yield of 31 primiparous Holstein cows was collected at Tifton, GA, from April 28 to July 19, 1993. Weather information was recorded on-farm and was available from weather stations in Georgia. Analyses used daily average of temperature–humidity index (THI). Effects of threshold of heat stress and the rate of decline in milk after the threshold were estimated. With on-farm weather data, threshold was at THI = 22 and rate of decline was − 1.12 kg of milk per unit of THI measured 2 days before milking. At the Tifton weather station, 3 km away from the farm, the threshold was THI = 20 and the rate was the same. With data from Macon, Columbus, Atlanta, and Athens stations, the threshold was at 20, 21, 20, and 20, respectively, and the rate of decline with a 2 day lag was − 0.88, − 1.02, − 0.90, and − 0.97 kg of milk per unit of THI. Subsequent analysis included 2260 test day records from the same farm from 1993 to 2003 and weather data from Tifton station. The highest rate of decline on milk yield of − 0.22 kg per unit of THI occurred at the threshold of 20 and no lag. For data restricted to 1999–2003, the threshold increased to 22 and the rate to − 0.46 kg per THI unit. Public stations provide satisfactory information for national genetic evaluation for heat stress. Critical parts in such an evaluation are modeling of test days and accounting for changes among farms and weather stations over time.     

Effect of floor cooling on performance of lactating sows during summer

Forty Landrace × Large White lactating sows were used to evaluate the effects of cooling of the floor when maintained under high temperature conditions during summer on their productive and reproductive performance. The sows were allocated in a completely randomized design with two treatments with 20 replicates according to parity number and body weight, with each animal being considered an experimental unit. The treatments consisted of cooling of the floor under the sow with water circulation at about 17 °C and no cooling. The resulting temperatures of the floor were 27.6 and 35.8 °C for the cooled and the control treatments, respectively. The sows from both treatments were exposed to average maximum and minimum environmental temperatures of 26.9 and 20.8 °C, respectively. Sows maintained on a cooled floor had a higher feed intake (6.47 vs. 5.61 kg/day; P < 0.01). Despite this higher intake, sows maintained on a cooled floor had higher body weight and body protein losses during the lactation period (P < 0.01) in connection with a higher milk yield and subsequent growth of the litter (2280 vs. 1798 g/day; P < 0.01). There was an effect of treatment on rectal temperature, surface temperatures and respiratory rate (P < 0.01) with lower values in sows submitted to floor cooling. It is concluded that floor cooling under the lactating sow improves its productive and reproductive performance, as well as the performance of its litter.     

崇测冰帽冰芯记录与塔克拉玛干周缘观测的相逆降水趋势——兼论大气尘埃含量对高海拔山地冰川物质平衡的贡献

对钻自西昆仑山崇测冰帽6530m处18.7m长冰芯的分析得到:尘埃含量的变化影响着崇测冰帽钻点处的物质平衡———与其它气溶胶相比,沙尘微粒是冰帽钻点处降雪的主要贡献因子;以沙尘作为冰核的降雪是钻点处降水的主导形式。与塔克拉玛干沙漠周缘地区地面观测资料比较显示:近60a来的冰芯积累量所反映出的冰帽降水量在减少,同时显示塔克拉玛干沙漠周缘地区暖季降水量在增加,而沙尘恰是连接沙漠周缘地区和附近冰川区气候变化的中介。值得注意的是,本研究对于崇测冰帽冰芯中降雪积累率与尘埃沉降通量一致降低的发现具有区域范围,甚至全球范围气候变化的意义。     

水杨酸与蔬菜作物抗性关系的研究进展

水杨酸在植物的抗病性方面发挥着重要的作用,近年来的研究表明,水杨酸在植物抗冷、热、盐、干旱、臭氧、重金属等环境胁迫方面有明显的作用。对近年来有关水杨酸在蔬菜抗逆境胁迫方面的研究进展进行综述,并提出一些研究思路。