丰度坐标系中岩浆岩系REE的演化线运动参数

指出丰度坐标系具多维性和共轭性．其坐标轴具对偶性；探讨了REE演化线、REE演化线三参数(演化强度、演化方向、演化空间位置)及其物理含义；指出REE演化线三个参数是体系的实测参数．是研究天然体系中元素质量运移的基础数据；侧重讨论了其中一个参数——REE演化方向在REE演化线类型划分上的应用、演化线类型的符号表示及其对岩石成因类型进行判别的示例。     

CHARACTERIZING SPECIES DISTRIBUTIONS BY PRODUCTIVITY AND MORTALITY RATES IN MULTISPECIES MODELS

Abstract The temporal change in species composition is one dimension that may be used to characterize ecosystems. Multispecies interactions and species abundance (or biomass) distributions can be analyzed by an N‐species Lotka–Volterra (LV) system of equations. We derive a statistical approximation to the stationary probability distribution of relative species biomass for a system of interacting species. The distribution is parameterized by the mean and variance of the LV species interaction coefficients and can exhibit a variety of shapes. Given this distribution, one can describe the state of the system, and subsequent perturbations within the system, in terms of shifts in the resulting stable distribution. Theoretical distributions with known properties were compared to distributions estimated from simulations and good agreement was found. Our analytical result could be used to develop “ecosystem indicators” for describing changes in the state of species within an ecosystem.     

金等离子体的荷态分配数的计算

在非局域热动力学平衡(Non-LTE)下,采用类氢近似,计算得出电子密度分别为6.0×10~(20) cm~(-3)、1.4×10~(21) cm~(-3)、1.0×10~(22) cm~(-3)和1.7×10~(22) cm~(-3)的条件下的三体复合、辐射复合、双电子复合系数随电子温度的变化,得出总的复合系数随电子温度的变化关系;结合相关的电离系数得出相应的离子占有数的比,最后,计算出一定电子密度和温度条件下Au~(48+)～Au~(52+)离子的离子丰度,从而得到金等离子体的荷态分配数与电子温度和电子密度的关系.     

Estimating the contribution of surfactant replacement therapy to the alveolar pool: An in vivo study based on 13C natural abundance in rabbits

Variation of the isotopic abundance of selected nutrients and molecules has been used for pharmacological and kinetics studies under the premise that the administered molecule has a different isotopic enrichment from the isotopic background of the recipient subject. The aim of this study is to test the feasibility of assessing the contribution of exogenous surfactant phospholipids to the endogenous alveolar pool in vivo after exogenous surfactant replacement therapy in rabbits. The study consisted in measuring the consistency of ¹³C/¹²C ratio of disaturated‐phosphatidylcholine palmitate (DSPC‐PA) in 7 lots of poractant alfa, produced over a year, and among bronchoalveolar lavages of 20 rabbits fed with a standard chow. A pilot study was performed in a rabbit model of lavage‐induced surfactant deficiency: 7 control rabbits and 4 treated with exogenous surfactant. The contribution of exogenous surfactant to the alveolar pool was assessed after intra‐tracheal administration of 200 mg/kg of poractant alfa. The ¹³C content of DSPC‐PA was measured by isotope ratio mass spectrometry. The mean DSPC‐PA ¹³C/¹²C ratio of the 7 lots of poractant alfa was −18.8‰ with a SD of 0.1‰ (range: −18.9‰; −18.6‰). The mean ¹³C/¹²C ratio of surfactant DSPC recovered from the lung lavage of 20 rabbits was −28.8 ± 1.2‰ (range: −31.7‰; −25.7‰). The contribution of exogenous surfactant to the total alveolar surfactant could be calculated in the treated rabbits, and it ranged from 83.9% to 89.6%. This pilot study describes a novel method to measure the contribution of the exogenous surfactant to the alveolar pool. This method is based on the natural variation of ¹³C, and therefore it does not require the use of chemically synthetized tracers. This method could be useful in human research and especially in surfactant replacement studies in preterm infants.     

尼龙1010－聚四氢呋喃多嵌段共聚物的ESCA研究

尼龙１０１０－聚四氢呋哺多嵌段共聚物（ＰＡ－ＰＴＭＧ）是一种性能良好的聚合物。本文用Ｘ射线光电子能谱（ＥＳＣＡ）和计算机分峰技术研究了不同软硬段分子量的ＰＡ－ＰＴＭＧ的表面化学组成，进行了试样ＥＳＣＡ谱峰归属的确定。结果表明，本体嵌段效果较好，但在样品表面上Ｏ／Ｎ原子比大于体相Ｏ／Ｎ原子比，即软段富集于表面，并且分相程度高的试样较分相程度低的试样其软段在表面富集得更多。     

The total column densities and fractional abundances of CH_3CN, CH_3OH, HCOOCH_3 and ~(13)CS in W51 cores

W51 is an HII region complex in Sagittarius spiral arm about 7.5 kpc away. There are three dense molecular cores identified in the 1′ region[1—3]. Massive stars form in these hot, dense, molecular cloud cores. These cores are characterized by small sizes, high temperature, and high gas densities. Although substantial effort has been invested in the study of hot cores, their role in the evolution of massive stars is not well under- stood. Observations of molecules in hot cores can be used t…     

低温NMR探头的应用

在过去10年中研发新核磁共振探头一直是制造者争夺的活跃领域. 最近，因其灵敏度的巨大提高，低温冷却探头得到人们格外的关注. 利用这一技术可大量节省谱仪机时. 对于低γ核可直接测定天然丰度样品而不必标记，这远比节省机时更为重要. 本文评述了针对5～10 Hz优化2 mg天然丰度噁唑烷酮抗菌素eperezolid的 CIGAR-HMBC-¹H-¹⁵N谱的比较，一个是采自美国瓦里安公司的5 mm低温探头，另一个是采自瓦里安公司传统室温3 mm 梯度三共振探头. 利用低温探头大约10 min就可记录到大部份¹H-¹⁵N远 程相关，26 min可观察到几乎所有的远程共振. 而在同样条件下使用3 mm传统梯度反式三共振探头无法得到有用的谱图，要想取得相同的结果须累加约18 h.     

Purity analysis of hydrogen cyanide, cyanogen chloride and phosgene by quantitative (13)C NMR spectroscopy

Hydrogen cyanide, cyanogen chloride and phosgene are produced in tremendously large quantities today by the chemical industry. The compounds are also particularly attractive to foreign states and terrorists seeking an inexpensive mass-destruction capability. Along with contemporary warfare agents, therefore, the US Army evaluates protective equipment used by warfighters and domestic emergency responders against the compounds, and requires their certification at > or = 95 carbon atom % before use. We have investigated the (13)C spin-lattice relaxation behavior of the compounds to develop a quantitative NMR method for characterizing chemical lots supplied to the Army. Behavior was assessed at 75 and 126 MHz for temperatures between 5 and 15 degrees C to hold the compounds in their liquid states, dramatically improving detection sensitivity. T(1) values for cyanogen chloride and phosgene were somewhat comparable, ranging between 20 and 31 s. Hydrogen cyanide values were significantly shorter at 10-18 s, most likely because of a (1)H--(13)C dipolar contribution to relaxation not possible for the other compounds. The T(1) measurements were used to derive relaxation delays for collecting the quantitative (13)C data sets. At 126 MHz, only a single data acquisition with a cryogenic probehead gave a signal-to-noise ratio exceeding that necessary for certifying the compounds at > or = 95 carbon atom % and 99% confidence. Data acquired at 75 MHz with a conventional probehead, however, required > or = 5 acquisitions to reach this certifying signal-to-noise ratio for phosgene, and >/= 12 acquisitions were required for the other compounds under these same conditions. In terms of accuracy and execution time, the NMR method rivals typical chromatographic methods.     

Examination of n-T_9 conditions required by N=50,82,126 waiting points in r-process

We examined the conditions of neutron density(n) and temperature(T_9) required for the N = 50, 82,and 126 isotopes to be waiting points(WP) in the r-process. The nuclear mass based on experimental data presented in the AME2020 database(AME and AME ±Δ) and that predicted using FRDM,WS4, DZ10, and KTUY models were employed in our estimations. We found that the conditions required by the N = 50 WP significantly overlap with those required by the N = 82 ones, except for the WS4 model. In addition, the upper(or lower) bounds of the n-T_9 conditions based on the models are different from each other due to the deviations in the two-neutron separation energies.The standard deviations in the nuclear mass of 108 isotopes in the three N = 50, 82, and 126 groups are about rms = 0.192 and 0.434 Me V for the pairs of KTUY-AME and WS4-KTUY models,respectively. We found that these mass uncertainties result in a large discrepancy in the nn-T_9 conditions, leading to significant differences in the conditions for simultaneously appearing all the three peaks in the r-process abundance. The newly updated FRDM and WS4 calculations can give the overall conditions for the appearance of all the peaks but vice versa for their old versions in a previous study. The change in the final r-process isotopic abundance due to the mass uncertainty is from a few factors to three orders of magnitude. Therefore, accurate nuclear masses of the r-process key nuclei, especially for ~(76) Fe,~(81)Cu,~(127)Rh,~(132)Cd,~(192)Dy, and ~(197)Tm, are highly recommended to be measured in radioactive-ion beam facilities for a better understanding of the r-process evolution.     

Glycosylation States on Intact Proteins Determined by NMR Spectroscopy

Protein glycosylation is important in many organisms for proper protein folding, signaling, cell adhesion, protein-protein interactions, and immune responses. Thus, effectively determining the extent of glycosylation in glycoprotein therapeutics is crucial. Up to now, characterizing protein glycosylation has been carried out mostly by liquid chromatography mass spectrometry (LC-MS), which requires careful sample processing, e.g., glycan removal or protein digestion and glycopeptide enrichment. Herein, we introduce an NMR-based method to better characterize intact glycoproteins in natural abundance. This non-destructive method relies on exploiting differences in nuclear relaxation to suppress the NMR signals of the protein while maintaining glycan signals. Using RNase B Man5 and RNase B Man9, we establish reference spectra that can be used to determine the different glycoforms present in heterogeneously glycosylated commercial RNase B.