Heavy-electron metals: new highly correlated States of matter

Heavy-electron metals exhibit highly correlated electronic behavior at liquid helium temperatures, with conduction-electron masses some hundred times the free-electron mass. Whether "normal," antiferromagnetic, or superconducting, their electronic behavior differs drastically from their ordinary metallic counterparts. The physical origin of the large mass and unusual superconducting and magnetic properties is the strong coupling between the conduction electrons and the local f-electron moment fluctuations characteristic of these materials.     

Gas-phase polymerization: ultraslow chemistry

The mechanism of formation of polymer molecules in the gas phase is difficult to study because the involatile polymers tend to condense out of that phase. However, new techniques, involving the use of cloud chambers, have enabled workers to use the nucleation of liquid drops in supersaturated monomer vapors to detect single polymer molecules and therefore to work with so few simultaneously growing polymers that aggregation and condensation are avoided. Chain polymerization in which the chain carriers are either radicals or ions can therefore be studied in the vapor. Furthermore, the ability to work with such small concentrations of growing polymeric radicals, for example, makes it possible to avoid encounters between them that lead to recombination and the formation of "dead" polymers that are incapable of further growth. Many aspects of gas-phase polymerization can be studied including, besides radical and ion chains, ring-opening polymerization, initiation, radiation-induced polymerization, and especially "ultraslow" chemistry.     

Gas-phase infrared spectrum of the protonated water dimer

The protonated water dimer is a prototypical system for the study of proton transfer in aqueous solution. We report infrared photodissociation spectra of cooled H+(H2O)2 [and D+(D2O2] ions, measured between 620 and 1900 wave numbers (cm-1). The experiment directly probes the shared proton region of the potential energy surface and reveals three strong bands below 1600 cm-1 and one at 1740 cm-1 (for H5O2+). From a comparison to multidimensional quantum calculations, the three lower energy bands were assigned to stretching and bending fundamentals involving the O...H+...O moiety, and the highest energy band was assigned to a terminal water bend. These results highlight the importance of intermode coupling in shared proton systems.     

Gas-phase ionic reactions: dynamics and mechanism of nucleophilic displacements

Nucleophilic displacement reactions (the SN2 reaction) of ions in the gas phase are a prototypical reaction system that allows a study of dynamics, mechanisms, and structure-energy relations. This article reviews aspects of the kinetics (especially the applicability of statistical reaction rate theory), the relation of structure and reactivity, and the effects of small numbers of solvent molecules on the reaction and compares the behavior of the ionic reaction in the gas phase with that in solution.     

Gas-phase inorganic chemistry: monovalent derivatives of calcium and strontium

The chemistry and spectroscopy of monovalent derivatives of calcium and strontium are described. Laser-driven chemical reactions of calcium and strontium vapors with a variety of small molecules have provided many new free radicals. In general, these species are analogous to the stable molecules obtained in traditional inorganic or organometallic chemistry, but some new families of molecules have been discovered.     

Late glacial climate record of midwestern United States from the hydrogen isotope ratio of lake organic matter

A hydrogen isotope time series obtained from an analysis of organic matter extracted from a lake core in Kalamazoo, southwestern Michigan, reveals four distinct isotope stages within the last 12,000 years that can be interpreted in terms of oscillations between cold and warm, dry climates. The most dramatic are a cold phase between 12,000 and 9000 years before present (B.P.), a warm, dry period between 8500 and 2000 years B.P., a cold period between 2000 and 1000 years B.P., and a warming trend since 1000 years B.P. The warming trend of the last 1000 years is comparable in magnitude to the mid-Holocene warm phase.     

Gas-phase ion chromatography: transition metal state selection and carbon cluster formation

Gas-phase ion chromatography can separate ions that have the same mass but differ in isomeric structure or electronic configuration. The main features of this technique are briefly outlined, and applications to a series of problems in transition metal chemistry and carbon cluster chemistry are described. Examples in transition metal chemistry include state-selective reactivity, excited state deactivation, and state-selective ligand binding energies. For clusters, ion chromatography was used to determine the structure of pure carbon cluster ions as a function of size from C(4) to C(84). The results indicate that carbon grows first in linear chains, transforms to monocyclic planar rings at about C(10), and forms new families of planar bi-, tri-, and tetracyclic rings at C(20), C(30), and C(40), respectively. Fullerenes, which mysteriously appear at C(30) and dominate by C(50), are generated by heating the planar ring systems above an isomerization barrier rather than by growth of graphite precursors.     

论新建本科院校经管类实验室的跨越式发展

文章从界定跨越式发展的本质内涵入手,分析了经管实验室面临的发展机遇、优势和重点要处理好的几个关系,并以嘉兴学院经管实验室建设发展为例,提出了新建本科院校经管实验室利用后发优势和重点突破策略,实现跨越式发展的对策。     

跨越管理学案例教学障碍的若干思考

案例教学是一种引导式、启发式、参与式教学,很适合于教授管理课程,应该在管理学教学实践中大力推广。近几年来,我们在大学本科管理课教学中推进案例教学法遇到了不少障碍和问题,本文针对这些障碍和问题提出相应的对策与措施。     

Gone with the wind: the origin of S0 galaxies in clusters

We present three-dimensional, high-resolution hydrodynamical simulations of the interaction between the hot ionized intracluster medium and the cold interstellar medium of spiral galaxies. Ram pressure and turbulent/viscous stripping remove 100% of the atomic hydrogen content of luminous galaxies like the Milky Way within 100 million years. These mechanisms naturally account for the morphology of S0 galaxies and the rapid truncation of star formation implied by spectroscopic observations, as well as a host of observational data on the neutral hydrogen (HI) morphology of galaxies in clusters.     

最小生成树算法的一种实现方法及其在代数理论上的探讨

图论中最小生成树问题的算法在现实中应用非常广泛,本文先根据其中的Kruskal算法的步骤并结合数据结构中单链表的特点对在计算机中如何实现这一问题进行了阐述和分析,最后又更加深入地探讨了如何利用代数理论来判定最小生成树涉及到的简单无向图连通性问题。     

Suspended particulate matter: concentration in the major oceans

Quantitative data from over 500 concentrates of suspended particulate material has been summarized statistically for the Atlantic, Pacific, and Indian oceans, the Gulf of Mexico, and the Caribbean Sea. From clear ocean water a majority of samples were in the range of 0 to 9.9 milligrams per 200 liters and the next largest number were in the range of 10 to 19.9 milligrams per 200 liters. Certain areas of cloudy or nepheloid water, observed photographically, contain relatively more samples in heavier concentration ranges and have larger mean values than clear ocean water.