Synthesis and antitumor activity of novel benzophenone derivatives

Novel benzophenone derivatives were synthesized and screened for cytotoxic and antitumor activity. Friedel-Crafts condensation was employed to construct the benzophenone skeleton. Among the compounds synthesized, morpholino and thiomorpholino benzophenones 3a-d exhibited potent cytotoxic activity against P388 murine leukemia and PC-6 human lung carcinoma cells in vitro, and compounds 3a, 3c, and 3j, when administered intraperitoneally, showed significant antitumor activity against the malignant ascites caused by intraperitoneal inoculation of P388 cells in mice.     

Continuous formation of slurry ice by cooling water–oil emulsion in a tube

Water-silicone oil emulsion with an additive, (C₂H₅O)₃SiC₃H₆NH₂, was examined as a heat storage material. A spiral tube used as a heat exchanger was immersed in a low temperature bath and the emulsion was circulated in the tube to make ice continuously. Ice was separated from the ice–liquid suspension in an outlet tank. The amount of formed ice, the temperatures of the inlet and the outlet of the heat exchanger, and the temperatures in the tube wall were measured and the overall heat transfer coefficient and the heat flux through the tube were calculated. Experiments were carried out, varying the flow rate, the temperature of cooling brine, and the thickness of tube wall. The condition under which slurry ice was formed continuously without adhesion of ice to the cooling wall was clarified. Though decrease in the thermal resistance of the tube increased the rate of ice formation or raised the brine temperature, it narrowed the range of the flow rate and of the brine temperature in which slurry ice was formed continuously.     

Dynamics of absorbed water in model composites of polyamide 6 and carbon fibre evaluated by differential scanning calorimetry

The crystallization and subsequent melting behaviour of absorbed water in the model composites of polyamide 6 (PA6) and carbon fibre were investigated by differential scanning calorimetry (DSC) in comparison with those in neat PA6, using the small rectangular specimens exposed to water at 90 °C. In the DSC curves of PA6 any exothermic peaks of crystallization and endothermic ones of melting were not observed, but a step corresponding to glass transition was observed at about −30 °C during the heating process. Thus water absorbed by neat PA6 was recognized as non-freezing bound water which does not crystallize, probably due to the strong interaction with the polyamide chains. On the other hand, for the model composite several exothermic peaks were clearly observed at temperatures ranging from −10 to −20 °C, and their intensity was increased with increasing the fibre content. The distinct endothermic peaks were detected around at 0 °C during the reversed heating process. The glass transition temperature was not affected by adding the carbon fibre. Comparing with the result of neat PA6 indicates that in the model composite water exists in a state near free water, besides the non-freezing bound water dispersed in the matrix polyamide. It is further implied that water is mainly accumulated in the matrix/fibre interfacial region with some microstructural heterogeneties or defects, in which the water molecules can easily move under much weaker interaction with the polyamide chains.     

Study on high performance ice slurry formed by cooling emulsion in ice storage (discussion on adaptability of emulsion to thermal storage material)

This study focuses on an emulsion as a new thermal storage material for ice storage. Two types of emulsions were formed using an oil–water mixture with a small amount of additive. A silicone, light and lump oils were used. The water contents of the emulsions were 70, 80 and 90%. The additive was an amino group modified silicone oil. No depression of freezing point was observed for the emulsions because of their hydrophobic properties. In order to determine the structure of the emulsions, their electrical resistances were measured. Moreover, components of the liquids separating from the emulsions were analyzed. The results indicated that one emulsion was a W/O type emulsion, while the other was an O/W type. Finally, adaptability of the two emulsions to ice storage was discussed, it was concluded that a high performance ice slurry could be formed by the W/O type emulsion.     

In-Situ Characterization of SiC–AlN multiphase ceramics

AlN and SiC can react and form a solid solution at temperatures above 1800 °C, a result that may be beneficial for sintering silicon carbide ceramics. The pressureless sintered AlN–SiC multiphase ceramics have reached high density at a temperature of 2100 °C for 1 hr in Ar. Analytical scanning transmission electron microscopy was then used to determine the grain boundary, fracture surface, and the local compositions. Because AlN has a higher solid vaporization pressure than SiC, the vaporization rate of the AlN solid would far exceed that of SiC at a sintering temperature. The vaporizing AlN was deposited on the surface of SiC powder; SiC grains then elongated in a random arrangement. The form of elongated rod crystals of 4H SiC is 5 to 8 m in length and 1 m in width. It resulted in the sample fracture section producing pulling-out and a strong tearing-open effect. The bending strength and the fracture toughness of the material obtained are 420 MPa and 4.40 MPa × m^1/2, respectively.     

残余应力对Si3N4/S45C连接体强度的影响

本文主要就Si3N4／S45C连接体在插入软金属及附加热循环的情况下，使残余应力发生变化，而讨论其对抗弯强度的影响．其结果为：（1）Si3N4表面边缘处的拉伸应力是影响连接体强度的主要原因．（2）抗弯强度和残余应力具有σ0＝-1．63σ＋658．1的线性关系．（2）周期性热循环对连接体的残余应力及抗弯强度有较大的影响；即发生加工硬化等使残余应力上升，产生裂纹等导致强度下降．     

Analysis of diffusional broadening of vesicular packets of catecholamines released from biological cells during exocytosis.

Secretion of catecholamines is observed as a series of current spikes when measured at the surface of a bovine adrenal medullary cell in culture with a carbon-fiber microelectrode operated in the amperometric mode. Prior work has shown that these spikes are due to detection of concentrated packets of catecholamines which are released from individual vesicles after their fusion with the cell membrane, a process known as exocytosis. The shape of the individual current spikes, detected with a 5-microns spacing between the hemispherical cell and the electrode, has been compared to the shape generated by a theoretical model. The model consists of an instantaneous point source of material on a surface which subsequently diffuses to a disk that consumes the emitted material. The pertinent diffusion conditions have been evaluated with finite difference and random walk digital simulations. The two methods give identical results when the point source is located on a plane. The more realistic simulation geometry, emission from a hemispherical surface, was evaluated with the random walk method. The simulations allow a set of criteria to be established to evaluate diffusion-controlled broadening of spike shape. The broad range of spike widths observed experimentally and their individual shapes measured with 5-microns cell-electrode spacing are consistent with diffusion from point sources randomly distributed across a hemispherical surface. The data can be described with the diffusion coefficient for catecholamines in free solution. The model enables evaluation of signal-to-noise losses and correction for diffusional losses which are dependent on electrode radius.(ABSTRACT TRUNCATED AT 250 WORDS)     

Enzyme-modified organic conducting salt microelectrode.

A miniaturized enzyme-modified electrode has been constructed and evaluated. The tip of a capillary-encased, carbon-fiber electrode is recessed, and tetrathiafulvalene-tetracyanoquinodimethane crystals are electrochemically deposited in the recessed tip. Flavoenzymes are placed in the recess by cross-linking with glutaraldehyde. The specific enzymes used are glucose oxidase to form a microbiosensor for glucose, and a combination of acetylcholine esterase and choline oxidase to form a microbiosensor for acetylcholine. The sensor is operated in an amperometric mode with Eapp = 150 mV versus a sodium saturated calomel electrode, and the response appears to be limited by the kinetics of the enzyme reaction. The effective maximum current density for the glucose electrode is greater than 600 microA/cm2. At low concentrations of glucose, oxygen provides a significant interference by attenuating the signal. The device is simple to prepare and has a rapid response time. Interference from ascorbate has been significantly reduced by the design and by addition of a layer of ascorbate oxidase. Although not yet suitable for use in tissue, the biosensors are suitable for detection in situations where oxygen concentrations do not frequently change.     

Fatigue failure of poly(methyl methacrylate) in alcohol environments

Fatigue tests of poly(methyl methacrylate) were conducted in environments of methanol, 1-butanol, and 1-octanol at room temperature under cyclic tensile loading at 10 Hz. The fatigue lifetime increased as the molar volume of the environmental alcohol increased, and indicated no correlation with the solubility parameter. The scanning electron micrographs of the fracture surfaces reveal that crazes strongly participate in the fatigue fracture, and suggest that a great increase in the fatigue lifetime in methanol brought about by pre-soaking the specimen in methanol for a period below 100 h, which has been previously reported, is caused by the combined effects both of the case II diffusion of methanol producing the softened matter and the internal compressive stress in the swollen surface layer and of a cooperative work of crazing, shear flow and/or shear cracking taking place under cyclic tensile loading.