Short communication: Variability in milk urea nitrogen and dairy total mixed ration composition in the northeastern United States

The main objective of this survey was to examine variability in milk urea nitrogen (MUN) for Dairy Herd Improvement Association (DHIA) herds in the northeastern United States (the Northeast), examine trends in dairy cow diet composition, and determine potential relationships for MUN and diet composition. Trends in milk fat and protein concentrations, milk yield, days in milk on test day, and lactation number of the cows were also evaluated. The data set for the survey included 10,839,461 DHIA dairy cow records from 2004 to 2015 for 13 states (CT, DE, MA, MD, ME, NH, NJ, NY, PA, RI, VA, VT, and WV) and was retrieved from Dairy Records Management Systems (Raleigh, NC). Average (across states and years) milk yield, milk fat, and milk protein were 31.6 ± 0.24 kg/d, 3.85 ± 0.021%, and 3.13 ± 0.013%, respectively. No obvious trends were observed for milk fat or protein content, but milk yield steadily increased during the survey period. Milk urea N concentration averaged 13.3 ± 0.13 mg/dL, with no obvious or consistent trends. Examination of variability in dairy feed cost and all milk price for the Northeast indicated that high MUN generally coincided with high feed cost and high milk price. For the diet composition survey, 9,707 records of total mixed ration (TMR) analyses, unrelated to the milk composition data set, from the Cumberland Valley Analytical Service (Maugansville, MD) database were examined. Concentration of TMR crude protein (CP) decreased from 17.1% in 2007 to 16.4% in 2015, but there was not an obvious trend in soluble protein concentration. Concentration of TMR neutral detergent fiber (NDF) and 24-h in vitro NDF degradability declined steadily during the survey period and was accompanied by a steady increase in TMR starch concentration. Examination of these unrelated data sets revealed lack of correlation between MUN and diet chemical composition. Thus, we conclude that individual cow MUN in Northeast dairy herds fluctuated between 2004 and 2015. It appeared that MUN followed variability in feed cost; however, ration feed ingredient data were not available to better define the reasons for the variations in MUN.     

开江—梁平海槽西侧飞仙关组不同类型鲕滩储层特征及其控制因素研究

针对开江—梁平海槽西侧飞仙关组鲕滩储层特征及主控因素存在较大差异的问题,基于鲕滩沉积演化规律，结合物性与地球化学分析，对开江—梁平海槽西侧飞仙关组鲕滩储层进行了研究。结果表明:伴随区内飞仙关期高能坡折带不断迁移，对应形成三期鲕滩，发育鲕粒云岩和鲕粒灰岩2类储层，物性及孔隙结构以鲕粒云岩型储层最优，次为鲕粒灰岩型储层。在鲕滩沉积的物质基础上，轻度蒸发海水诱发的回流渗透叠加深部热液白云石化作用共同控制鲕粒云岩型储层的形成，而有机酸主导的埋藏期保孔-扩孔作用既进一步改善先期形成的鲕粒云岩型储层，又影响了鲕粒灰岩型储层的形成。该研究对鲕滩储层的差异性成储机理相关研究有很好的借鉴意义。     

渤海海域石臼坨凸起东北缘沙河街组一段+二段砂砾岩储层差异定量表征

为了探究砂砾岩储层物性差异的成因，以石臼坨凸起东北缘秦皇岛19-A构造和秦皇岛29-B构造沙河街组一段（沙一段）+沙河街组二段（沙二段）为例，通过岩心、铸体薄片、岩石物性、全岩分析、流体包裹体等资料，定量分析了砂砾岩储层的差异、控制因素以及孔隙演化过程。研究结果表明：①沉积作用控制了不同构造的岩性差异和原始物性差异，是其主要因素。秦皇岛29-A构造沙一段+沙二段主要发育扇三角洲中砂岩、粗砂岩夹薄层砾岩储层，粒度相对较细，砾岩比例小（约为2%），粒间以少量泥质为主，物性好，原生孔隙为主。秦皇岛29-B构造沙一段+沙二段主要发育扇三角洲含生物碎屑的砾岩与中砂岩、粗砂岩互层的储层，粒度较粗，砾岩比例高（约为57%），粒间以大量方解石、白云石等胶结物为主，物性差，次生孔隙发育。受控于沉积作用的差异，秦皇岛29-A构造沙一段+沙二段储层原始孔隙度为32.7%，秦皇岛29-B构造储层原始孔隙度为29.6%。②不同沉积作用影响下，砂砾岩储层经历了差异成岩演化。在长期碱性→酸性→短暂碱性的流体演化过程中，秦皇岛29-A构造经历了较强的压实作用（损失孔隙度为16.2%，孔隙度损失率为47.1%）和较弱的胶结作用（损失孔隙度为5.5%，孔隙度损失率为15.5%）；秦皇岛29-B构造经历了较弱的压实作用（损失孔隙度为10.1%，孔隙度损失率为35.6%）和较强的胶结作用（损失孔隙度为14.9%，孔隙度损失率为53.2%）。2个构造均经历了相近的强烈溶解作用（秦皇岛29-A构造增加孔隙度为8.3%，增孔率为24.7%；秦皇岛29-B构造增加孔隙度为7.2%，增孔率为25.8%）。③孔隙定量演化揭示，不同构造的储层孔隙演化过程具有明显的差异性。     

A novel ultra-high-temperature oxidation protective MoSi2-TaSi2 ceramic coating for tantalum substrate

To protect refractory metal against oxidation at ultra-high temperatures, a MoSi₂-TaSi₂ ceramic coating was prepared on a pure tantalum (Ta) substrate using a novel three-step process, which included dip-coating with a molybdenum slurry, vacuum sintering, and halide-activated pack cementation (HAPC). The original coating had a MoSi₂-TaSi₂ double-layer structure from the surface to the substrate. After oxidation at 1700°C for 8 h in air, the coating exhibited a complex multi-layer structure composed of SiO₂-Mo₅Si₃-MoSi₂-(Mo,Ta)₅Si₃-TaSi₂-Ta₅Si₃ from the outer layer to the inner layer, due to the high-temperature phase transition and diffusion of Si and O. The coating effectively protected the Ta substrate at 1700°C for 12 h without failure, thereby demonstrating great improvement to its service life in an ultra-high-temperature aerobic environment. The protective effect was attributed to the integrity of the ceramic coating and the formation of a dense, uniform SiO₂ film that effectively lowered the inward oxygen diffusion rate.     

长沙太平街湘绣产品的市场调查与分析

长沙是湘绣的发源地,集湘绣的研发、生产、销售于一体,拥有着独特的湘绣文化。太平街坐落于长沙市老城区南部,是一条商业繁荣、游客众多的文化老街,主要以销售长沙当地特产、传统手工艺品、特色小吃等为主,极具湖湘文化魅力,吸引了许多外来游客。笔者以太平街为研究范围,对太平街区域内的湘绣销售情况进行了问卷调查,调查显示,太平街区域内的湘绣产品销售情况与湘绣产品的种类和游客群的构成特征关系密切。基于上述调查结果,笔者对当下的长沙地区湘绣销售的前景和未来湘绣文化产品的推广,进行了分析并提供了新的思路。     

基于GIS和TOPSIS-PSR的湖南省洪涝灾害后恢复力评价

针对当前洪灾恢复力评估对洪灾与承灾体、自然环境之间关系阐释不明的问题,以湖南省洪灾后恢复力为研究对象,提出应用压力-状态-响应(PSR)概念构建洪灾评价指标体系,在此基础上建立了TOPSIS诊断模型,并基于GIS平台予以可视化。结果表明,PSR概念以因果关系描述洪灾恢复力的多元结构与功能差异,对指导灾害管理具有积极意义;就压力而言,湘西北、湘南致灾压力较小,湘中致灾压力略大;状态指数分布与全省经济社会发展水平一致,长株潭地区较高;响应分析显示,湘北地区防洪治理效果显著。全省洪灾恢复力呈条带分布,湘北-湘东洪灾恢复力较好,湘中、湘西南和岳阳洪灾恢复能力偏差。该量化模型还具有易于维数扩充、可操作的特点,应用前景良好。     

高效液相色谱法测定不同产地湘莲中荷叶碱、 莲心碱、芦丁的含量

目的建立高效液相色谱法同时测定湘莲中荷叶碱、莲心碱、芦丁的方法。方法在酸性条件下超声提取3种待测组分。色谱条件如下:C_(18)(250 mm×4.6 mm,5μm)色谱柱;流动相:甲醇-0.1 mol/L乙酸铵(用乙二胺调节pH值至7.5~8.0)(55:45,V:V);流速:1.0 m L/min;检测波长:275 nm;柱温30℃;进样量10μL。结果荷叶碱、莲心碱、芦丁分别在7.636~152.7μg/mL(r~2=0.9999,n=5)、7.543~150.9μg/mL(r~2=0.9995,n=5)、7.543~150.9μg/mL(r~2=0.9998,n=5)范围内线性关系良好,加标回收率为96.9%~100.5%之间,相对标准偏差(relative standard deviation,RSD)为1.1%~1.4%。结论该法同时测定湘莲中荷叶碱、莲心碱、芦丁,简单快速,定量准确,可以为评价不同产地湘莲功效成分提供参考。     

塔里木盆地塔中地区北坡奥陶系热液蚀变作用

沉积盆地超深层(4 500 m)不仅具有与浅层和中深层不同的温压条件,而且流体体制也存在显著差异。以塔里木盆地塔中地区北坡NE向走滑断裂带上的SN4井超深层的中下奥陶统碳酸盐岩硅化段为研究对象,在详细的成岩作用研究基础上,开展了成岩矿物流体包裹体、稳定O-C和Si-O同位素以及常量、微量和稀土元素等系统分析。结果表明,超深层中下奥陶统碳酸盐岩储层存在3种流体端元类型:1深成上升流热液;2外源同生卤水;3这2种热流体与储层同生海水的混合流体。其为经历2种流体-岩石相互作用体制演化的结果:1大气淡水-同生海水重力流演化体制;2火成岩活动驱动远端热液与同生卤水混合上升流演化体制。其中,上升流具有2个流体来源:1受火成岩活动驱动远端热液,具有中低温度、中高盐度、富Si质和富含CO2和H2S挥发份水解成强酸的特征,不仅成为缝洞型储层热液-岩石相互作用的溶剂,而且可能发生了第1期天然气充注;2来源于下伏寒武系烃源岩层的中低温、富Ca和CH4的碱性热卤水,不仅形成了晚期裂缝刀刃状方解石脉,而且发生了第2期天然气充注成藏。依据成岩矿物组合和温度控制矿物学原理构筑其储层化学反应路径模型,结合储层物性测定结果,初步估算这种上升流热液蚀变作用对储层孔隙度的贡献达约8%。由此表明,多期火成岩活动和多期断裂活动不仅为深成上升流提供了动力和通道,而且作为一个独立因素对超深层缝洞型碳酸盐岩储层的形成和天然气的成藏起到了重要的控制作用。综上可推论,塔里木盆地中央火成岩带超深层将是这类热液蚀变缝洞型储层发育带和有利的天然气聚集带。     

略论湖湘文化对长沙窑装饰艺术影响

长沙窑是中国陶瓷釉下彩的发源地。在陶瓷装饰上,从注重瓷器的釉色美转移到瓷器彩绘装饰美的发展方向,它是我国釉下彩绘的第一个里程碑。古老的长沙窑,虽然己经逝去,但我们能从它民间名窑画风洒脱、俊逸、空灵的釉下彩装饰艺术中感受到湖湘文化精神气质,客观地反映了当时人们的思想情趣和民间风俗,也为后人研究中国陶瓷史以及现代陶瓷装饰留下丰富而详实的考证和借鉴。