Saturation in milk and meat fats

Meat and milk products from ruminants (cows, goats, sheep, and beef animals) contribute 35 to 40 percent of the fat in the average American diet. Such fat is highly saturated, containing less than about 4 percent polyunsaturated fatty acids. The unsaturated plant lipids (fats) ordinarily consumed by the ruminant are hydrogenated (saturated) in the rumen. Transport and incorporation of this hydrogenated fat into meat and milk follows. Rumen hydrogenation does not take place until the fat is broken down to free fatty acids, thus establishing the fact that lipolysis is an essential feature of the process. Circumvention of this lipolysis may lead to more-unsaturated meat and milk fat.     

饱和度对AVO影响探讨

介绍了Biot-Gassmann方程及其7个假设条件,通过该方程分析了饱和度对密度和纵横波速度的敏感程度以及饱和度对纵横波反射系数的影响。研究表明,纵波速度和密度对于区分含气砂岩与含油砂岩是较为敏感的。总体上,饱和度对纵波的敏感性比横波要更强一些。     

Body-centered cubic iron-nickel alloy in Earth's core

Cosmochemical, geochemical, and geophysical studies provide evidence that Earth's core contains iron with substantial (5 to 15%) amounts of nickel. The iron-nickel alloy Fe(0.9)Ni(0.1) has been studied in situ by means of angle-dispersive x-ray diffraction in internally heated diamond anvil cells (DACs), and its resistance has been measured as a function of pressure and temperature. At pressures above 225 gigapascals and temperatures over 3400 kelvin, Fe(0.9)Ni(0.1) adopts a body-centered cubic structure. Our experimental and theoretical results not only support the interpretation of shockwave data on pure iron as showing a solid-solid phase transition above about 200 gigapascals, but also suggest that iron alloys with geochemically reasonable compositions (that is, with substantial nickel, sulfur, or silicon content) adopt the bcc structure in Earth's inner core.     

奶牛乳腺长链脂肪酸转运的研究进展

奶牛乳脂中的长链脂肪酸（LCFA）JL乎全部来源于从消化道吸收并转运人血液的食物外源性LCFA,然后跨膜进入乳腺上皮细胞参与乳脂合成,而参与LCFA跨膜运输的脂肪酸转运蛋白有：脂肪酸转运蛋白家族（Fattyacid transport proteins,FAPTs）、脂肪酸转位酶（Fatty acid translocase,FAT／CD36）、脂肪酸结合蛋白家族（Fattyacid binding proteins,FABPs）和小窝蛋白（Caveolinproteins）。文章在综述LCFA跨膜运输研究的基础上,重点介绍4种LCFA转运蛋白的研究进展,发现在奶牛乳腺中表达的只有FAT／CD36和FABPs,而FATPs和小窝蛋白在奶牛乳腺中是否表达并参与LCFA的转运仍有待进一步研究确定。因此,应利用营养学、分子生物学和细胞生物学等方法,在体内和体外对FAT／CD36、FABPs、FATPs和小窝蛋白在泌乳期奶牛乳腺中的表达规律、作用机理进行深入研究,以探明其在乳腺LCFA转运中的作用及调控机制．并为优化乳脂组成实施的营养调控提供科学依据。     

巢湖流域农田土壤磷吸持指数及吸持饱和度特征

农业活动对水体磷污染的影响已成为公众关注的焦点。土壤对磷具有一定的固定能力，可以采用土壤磷吸持指数（PSI）和吸持饱和度（DPSS）来表征土壤中的磷向水体释放的风险。对巢湖流域各类土壤的研究表明，土壤的固磷能力相比太湖及国外其他地区普遍较低，红壤和石灰岩土的固磷能力相对较强，而紫色土的固磷能力最弱。土壤磷的吸持饱和度和吸持指数之间存在显著的负相关关系，吸持指数较高的红壤和石灰岩土，其土壤磷吸持饱和度表现较低；而紫色土对磷较容易饱和，磷吸持饱和度普遍偏高。已有30％的土壤其磷吸持饱和度超过25％的流失临界值，应重视其可能对环境造成的影响。     

关于旅游区饱和与超载问题的思考

旅游活动已逐渐成为人们生活的重要组成部分,由旅游热所引起的旅游环境超容量承载问题已逐渐引起社会越来越多的关注和重视.从旅游饱和与超载的概念出发,分析了旅游饱和与超载的形式,阐述了超载现象带来的消极影响,并提出了解决饱和与超载问题的方法.     

Crystal structure of the long-chain fatty acid transporter FadL

The mechanisms by which hydrophobic molecules, such as long-chain fatty acids, enter cells are poorly understood. In Gram-negative bacteria, the lipopolysaccharide layer in the outer membrane is an efficient barrier for fatty acids and aromatic hydrocarbons destined for biodegradation. We report crystal structures of the long-chain fatty acid transporter FadL from Escherichia coli at 2.6 and 2.8 angstrom resolution. FadL forms a 14-stranded beta barrel that is occluded by a central hatch domain. The structures suggest that hydrophobic compounds bind to multiple sites in FadL and use a transport mechanism that involves spontaneous conformational changes in the hatch.     

12种常见食用蘑菇脂肪酸绝对含量的测定

了解１２种常见食用蘑菇长链脂肪酸的绝对含量。方法：以正十七酸为内ｌ－ＣＨ３ＯＨ抽担和酯化,正己烷提取脂肪酸甲酯化物,进行毛细管气相色谱分析,结果与结论：１２种食用蘑菇所含脂肪的绝对含量不同。     

从饱和度再认识非饱和表层土吸力

为了探讨非饱和土水膜中的重力水对总吸力的影响,根据饱和度大小情况,将非饱和土中的水、气形态分成了四类,即界限饱和度Sr1,Sr2,Sr3,Sr4.分析了非饱和土中的总吸力组成和水膜中重力水对总吸力的影响,并推导出界限饱和度Sr2条件重力水对总吸力影响的计算公式,在此基础上给出了颗粒级数分别为10-3mm~100mm的总吸力与饱和度的关系图.最后选择了一种试验值模拟比较.模拟比较表明,考虑重力水的作用下理论计算值与实测值更加吻合,从而证实了重力水对吸力的影响是不可忽略的.     

执行器饱和的线性连续系统的镇定

针对控制系统中广泛存在饱和问题,主要研究执行器饱和线性连续系统的镇定问题并进行吸引域估计。首先根据Finsler’s 引理和Lyapunov 函数方法研究系统稳定的充分条件,得到执行器饱和控制系统稳定的新判据。其次,在稳定条件下,应用凸组合方法和新引入的自由权矩阵使得系统吸引域估计具有更小的保守性,将所得非线性矩阵不等式转化为线性矩阵不等式,给出求解最大吸引域的优化方法和状态反馈控制器的设计方案。最后通过仿真算例验证结果的有效性和可行性。     

输入饱和受限的短时延网络控制系统指数稳定性研究

基于线性不变被控对象,固定时延不大于一个采样周期,且存在输入饱和受限的网络控制系统,采用对角矩阵法处理饱和环节,最优线性二次型方法设计离散最优控制器,并得出网络控制系统局部指数渐近稳定时的最大吸引域和离散最优控制器结论。仿真结果表明建模方法的可行性和有效性。     

江西省有机肥资源利用现状及发展对策

2001年对江西省各市县有机肥料资源、利用状况、商品有机肥料生产情况及用户进行了调查。结果表明,江西省有机肥料资源量为13411.0万t,利用量为6199.4万t,商品有机肥产量4.1万t,有机肥料利用率为46.2%。针对目前有机肥发展存在的绿肥种植面积下降,单产低;作物秸秆总量减少,秸杆资源未充分利用;农民积造的农家肥数量锐减,粪尿类资利用率低;有机肥商品化率低等问题,提出了制订政策,加强立法;发展经济绿肥,搞好良种繁育;抓好秸杆还田,严禁就地焚烧;抓好有机肥积造;提高有机肥商品化率的建议和对策。     

Calcium Carbonate: Factors Affecting Saturation in Ocean Waters off Bermuda

Bermuda marine waters are not in equilibrium with the bulk carbonate sediments with which they are in contact, and they are supersaturated with respect to pure calcite. This apparent supersaturation seems to result from a metastable equilibrium between sea water and the most soluble solid phase available locally in excess.     

Harnessing nonlinearity: predicting chaotic systems and saving energy in wireless communication

We present a method for learning nonlinear systems, echo state networks (ESNs). ESNs employ artificial recurrent neural networks in a way that has recently been proposed independently as a learning mechanism in biological brains. The learning method is computationally efficient and easy to use. On a benchmark task of predicting a chaotic time series, accuracy is improved by a factor of 2400 over previous techniques. The potential for engineering applications is illustrated by equalizing a communication channel, where the signal error rate is improved by two orders of magnitude.     

输入具有饱和非线性的离散系统闭环稳定性

基于矩阵范数和离散时间系统李雅普诺夫定理，给出了控制输入具有饱和非线性特性的状态反馈控制系统的闭环渐近稳定性判据。     

白色长链脂肪醇醚羧酸盐的合成研究

以16-18碳脂肪醇-9-聚氧乙烯醚(AEO9)和氯乙酸为原料,采用羧甲基化法合成长链脂肪醇聚氧乙烯醚羧酸盐(简称脂肪醇醚羧酸盐)。通过正交试验确定了较佳的反应条件,反应时间为6 h,反应温度为80℃,AEO9、C lCH2COOH、NaOH投料体积比为1∶1.1∶2.53。采用分批投料、用活性炭脱色的方法控制产物颜色为白色;再通过分离、提纯去除杂质,提高产品纯度和产率。     

Common structure of soluble amyloid oligomers implies common mechanism of pathogenesis

Soluble oligomers are common to most amyloids and may represent the primary toxic species of amyloids, like the Abeta peptide in Alzheimer's disease (AD). Here we show that all of the soluble oligomers tested display a common conformation-dependent structure that is unique to soluble oligomers regardless of sequence. The in vitro toxicity of soluble oligomers is inhibited by oligomer-specific antibody. Soluble oligomers have a unique distribution in human AD brain that is distinct from fibrillar amyloid. These results indicate that different types of soluble amyloid oligomers have a common structure and suggest they share a common mechanism of toxicity.     

Structure of a 16-nm cage designed by using protein oligomers

Designing protein molecules that will assemble into various kinds of ordered materials represents an important challenge in nanotechnology. We report the crystal structure of a 12-subunit protein cage that self-assembles by design to form a tetrahedral structure roughly 16 nanometers in diameter. The strategy of fusing together oligomeric protein domains can be generalized to produce other kinds of cages or extended materials.