Waterlogged molecules

Measurements of vapor pressures over their aqueous solutions indicate that organic compounds show profound differences in hydrophilic character. These differences are of such magnitude as to suggest an important role for changing solvation in determining free energy changes associated with metabolic transformations in water, and in governing structural equilibria of proteins and other large molecules in water. When two or more functional groups are present within the same solute molecule, their combined effects on its free energy of solvation are commonly additive. Striking departures from additivity, observed in certain cases, indicate the existence of special interactions between different parts of a solute molecule and the water that surrounds it. Similar considerations presumably apply to activated intermediates in the interconversion of biological materials.     

Cell adhesion molecules

It has been proposed that cell-cell recognition occurs by means of local cell surface modulation of a small number of proteins rather than by expression of large numbers of different cell surface markers. Several different cell adhesion molecules (CAM's) have now been found in a number of vertebrate species in different tissues such as liver and striated muscle and even in a single complex structure such as the brain, where different molecules specific for neurons and glia have been identified. The neuron-specific molecule is involved in early embryonic events but also mediates neurite fasciculation, neuromuscular interaction, and orderly layering of neural tissue. It undergoes local surface modulation with loss of sialic acid during development. A failure of this process is closely correlated with connectional disorders in the staggerer mutant of the mouse. The accumulated data on this and other CAM's favor modulation theories rather than strict chemoaffinity theories of cell-cell recognition.     

椰子酸奶的研制

探讨了凝固型椰子酸奶的工艺条件、配方及生产影响因素。试验结果表明，在纯椰奶为10％(质量分数，下同)的稀释椰奶中加入6％的脱脂奶粉、10％的蔗糖及0．6％的稳定剂，经均质、杀菌、接种等工艺可制得酸甜可口的椰子酸奶。     

Bose-Einstein condensation of molecules

We report on the Bose-Einstein condensation of more than 10(5) Li2 molecules in an optical trap starting from a spin mixture of fermionic lithium atoms. During forced evaporative cooling, the molecules are formed by three-body recombination near a Feshbach resonance and finally condense in a long-lived thermal equilibrium state. We measured the characteristic frequency of a collective excitation mode and demonstrated the magnetic field-dependent mean field by controlled condensate spilling.     

Reactions of oriented molecules

Beams of oriented molecules have been used to directly study geometrical requirements in chemical reactions. These studies have shown that reactivity is much greater in some orientations than others and demonstrated the existence of steric effects. For some reactions portions of the orientation results are in good accord with traditional views of steric hindrance, but for others it is clear that our chemical intuition needs recalibrating. Indeed, the information gained from simultaneously orienting the reactants and observing the scattering angle of the products may lead to new insights about the detailed mechanism of certain reactions. Further work must be done to extend the scope and detail of the studies described here. More detailed information is needed on the CH(3)I reaction and the CF(3)I reaction. The effects of alkyl groups of various sizes and alkali metals of various sizes are of interest. In addition, reactions where a long-lived complex is formed should be studied to see if orientation is important. Finally, it would be of interest to apply the technique to the sort of reactions that led to our interest in the first place: the S(N)2 displacements in alkyl halides where the fascinating Walden inversion occurs.     

鲟鱼剥制标本的制作

鱼类标本的制作方法较多,依个体大小及用途的不同,有浸渍标本、剥制标本、骨骼标本等.剥制标本是剥取动物的外皮,内面涂以防腐剂或将整张皮用防腐固定液浸泡,再用钢棍、铅丝、木架和填充物支撑制成的标本,它的制作是动物学技术的主要内容之一.剥制标本主要供教学、研究、博物馆陈列观摩和家庭等场所的陈设.现将鲟鱼（Acipenser）剥制标本制作过程介绍如下.     

Nucleation on photoexcited molecules

On irradiation with light of suitable wavelength and intensity, certain organic compounds, even at very low concentrations, cause very efficient nucleation of supersaturated vapors. A mechanism is suggested to account for this phenomenon. Nuclei containing only a few photoexcited molecules are responsible for the nucleation.