Methylglyoxal: A newly detected and potentially harmful metabolite in the blood of ketotic dairy cows

Ketosis causes serious economic losses for the modern dairy industry because it is a highly prevalent metabolic disease among cows in high-producing herds during the transition period. Due to some striking similarities between diabetes in humans and ketosis in dairy cows, there is potential for the use of methylglyoxal (MGO)—commonly used in human diabetics—as a biomarker in dairy cattle. However, currently no data are available about the presence of MGO in the serum of dairy cattle or about the characteristics of its production or its potential contribution in the pathogenesis of ketosis. To determine the potential origin and pathway of formation of MGO, cows in different metabolic conditions [i.e., non-subclinically ketotic dairy cows in early lactation (n = 7), subclinically ketotic dairy cows in early lactation (n = 8), overconditioned dry cows (BCS >4.25, n = 6), and nonlactating heifers (n = 6)] were selected. Serum MGO concentrations were determined and correlated with indicators of the glucose and lipid metabolism and with haptoglobin (Hp) as an inflammatory marker. The serum MGO concentrations in subclinically ketotic cows (712.60 ± 278.77 nmol/L) were significantly greater than in nonlactating heifers (113.35 ± 38.90 nmol/L), overconditioned dry cows (259.71 ± 117.97 nmol/L), and non-subclinically ketotic cows (347.83 ± 63.56 nmol/L). In serum of lactating cows, concentrations of glucose and fructosamine were lower than in heifers and were negatively correlated with MGO concentrations. Even so, concentrations of metabolic and inflammatory markers such as dihydroxyacetone phosphate, nonesterified fatty acids, β-hydroxybutyrate, acetone, and Hp were remarkably higher in subclinically ketotic cows compared with nonlactating heifers; these metabolites were also positively correlated with MGO. In human diabetics elevated MGO concentrations are stated to originate from both hyperglycemia and the enhanced lipid metabolism, whereas higher MGO concentrations in subclinically ketotic cows were not associated with hyperglycemia. Therefore, our data suggest MGO in dairy cows to be a metabolite produced from the metabolization of acetone within the lipid metabolization pathway and from the metabolization of dihydroxyacetone phosphate. Furthermore, the highly positive correlation between MGO and Hp suggests that this reactive compound might be involved in the proinflammatory state of subclinical ketosis in dairy cows. However, more research is needed to determine the potential use of MGO as a biomarker for metabolic failure in dairy cows.     

基于像素点灰度差的Harris角点检测算法

针对Harris算法在图像处理过程中特征点提取实时性和抗噪能力较差、计算量大的问题,提出一种结合像素点灰度差的Harris角点检测算法。将被检测点与半径为3的邻近圆周上16个像素点作对比,以此计算非相似像素点的个数来确定候选角点,通过Harris角点响应函数提取角点,并结合SUSAN算法的思想去除伪角点。实验结果表明,改进算法提高了原算法的实时性,增加了角点提取的数量,并且能有效去除大多数伪角点,提高图像角点检测的速度和正确性。     

基于事故树理论的综采面危险程度分级技术

为了提高煤矿安全管理的针对性和有效性,介绍了事故树模糊分析理论,利用风险矩阵法提出了综采面的危险程度分级判定方法,得出了基于评价总分T的危险程度分级判定准则:T≥88(危险区域),55≤T<88(威胁区域),T<55(相对安全区域),并在钱营孜矿3212综采面进行了现场应用.结果表明,钱营孜矿3212综采面为威胁区域,发生可能性最大的事故是冲击地压事故,概率范围为(0.29,0.73);可能性最小的事故是煤尘爆炸,概率范围为(4.08×10-11,4.32×10-11).在日常安全管理过程中,应当加强对冲击地压事故的防治和管理,抓住重点,合理分配资源,最大程度提高煤矿安全管理效率.     

四川某选厂球磨分级自动控制系统

为四川某矿业集团选矿厂设计了球磨分级自动控制系统。在一段球磨分级过程中,通过检测球磨机负荷和螺旋分级机的溢流浓度,采用串级PID控制,实现对新给矿量和溢流浓度的控制,从而间接控制磨矿浓度和螺旋分级机的溢流粒度。在二段磨矿的旋流器给矿泵池,使用超声波液位计和核子密度计分别检测泵池液位和矿浆浓度,并对其进行控制,使旋流器有较好的工况。同时用计算机进行实时监控,显示各重要数据和设备状态及报警等。详细说明了各参数的控制方案和整体设计思路。     

FCC汽油选择加氢脱硫催化剂的研制及其性能评价

以模拟汽油为原料油,在传统的CoMo/γ-Al_2O_3催化剂上添加Fe,K,Mg金属助剂,制备了相应的改性催化剂;研究了金属助剂种类及其负载量对催化剂物化性质及其加氢脱硫选择性的影响;并用XRD,BET,H_2-TPR等技术对催化剂的物化性质进行了表征。实验结果表明,负载0.5%(基于Fe的氧化物质量)Fe的CoMo/γ-Al_2O_3催化剂对FCC汽油具有较好的加氢脱硫选择性,并用于处理大港FCC汽油时可将汽油中的硫含量降至50μg/g以下,辛烷值只损失1～2个单位,达到了欧Ⅳ汽油标准,且Fe改性的CoMo/γ～Al_2O_3催化剂具有较好的稳定性。     

难忘的孙筱祥先生

人生在世,父母是启蒙的先生.可是中国传统讲究'异子而教'.主要还在于各级学校任教的先生们.就中影响最广而深的当是迄今从事社会工作最相关的学科和专业的先生.我今生有幸成为清华大学和北京农业大学合办、通过吴良镛和汪菊渊两位大师远瞻创议于 1951 年成立的造园专业一年级新生.时在 1951 年秋,基础课和专业基础课都由两校名师任教.打下了全面扎实的基础.     

屡得感悟挚贺寄畅老人生生不息

逢寄畅园建园490周年,颇有感发,遂浮想命笔,以表挚贺。寄畅园为明代遗构,布局自然简约,景面文心,是鲜有的“虽由人作,宛自天开”的园林。通过明旨、相地、问名、布局、理微、余韵、借景等方面分析寄畅园之造园理法,并着重分析寄畅园筑山、理水之要点。     

徽州传统民居民间艺术文化意蕴探究

民间艺术是中国民族传统文化中非常重要的组成部分,具有鲜明的地域性特征,与传统发展密切相关,包含了材料技艺、社会信仰、乡民的价值观念、角色认知、生产生活行为中衍生的文化载体。基于此,本文从文化表征、认同、混融三方面探究了徽州传统民居中民间艺术文化意蕴,希望能够对民间艺术研究有所帮助。     

晶种法制备氢氧化镁阻燃剂粉体

以卤水为原料,以氢氧化钠为沉淀剂,采用加入晶种两步合成法制备出类似立方状的氢氧化镁粉体颗粒.通过SEM,XRD和粒度分布考察了不同水热时间氢氧化镁粒子的形貌、大小、(101)面内应变和粒度分布的变化.研究发现采用加入晶种两步合成法,氢氧化镁的生长速度明显快于未加入晶种的氢氧化镁的生长速度,且其分散性更好,过滤时间更短.前6 h氢氧化镁为片状,24 h后其宽厚比接近1;(101)面内应变的增加主要集中在6 h～12 h时间段内,12 h后增加速度明显变缓.