EFFECTS OF COUPLING AGENTS ON THE CRYSTALLIZATION BEHAVIOR OF PP/T-ZnOw COMPOSITES

The objectives of this paper are to understand the crystallization behavior of polypropylene(PP)composites with surface modified tetra-needle-shaped zinc oxide whisker(T-ZnOw).T-ZnOw was surface modified with different coupling agents,such as silane coupling agents(KH-550,KH-560)and titanate coupling agent(NDZ-105),in order to improve the compatibility between PP and T-ZnOw.DSC and POM were used to characterize the melt and crystallization behavior and the crystalline structures of the composites,respectively.The results show that the surface modified T-ZnOw acts as a nucleating agent of PP crystallization,depending on the coupling agent used for modification.KH-550 and KH-560 have more apparent role in improving the interfacial interaction than NDZ-105 and induce PP crystallization at higher temperature and with smaller spherulites size.The results also suggest that the crystallization behavior depends on not only the content of coupling agent,but also the content of the surface modified T-ZnOw used in the composites.     

EFFECTS OF COUPLING AGENTS ON THE RHEOLOGICAL BEHAVIOR OF KAOLIN FILLED POLYAMIDE 6

An experimental study was carried out to investigate the effects of coupling agents on the rheological properties of kaolin filled polyamide 6(PA6). We have investigated the state of dispersion and interfacial interaction of the filled systems, using 'h:anning electron microscopy (SEM) and Molau test, respectively. It is found that the addition of the coupling agents to the PA6/ kaolin (20 wt percent) significantly decreases the melt viscosity and the melt elasticity (first normal stress difference). Moreover, the states of dispersion and the polymer/filler interactions have significant influences on the rheological properties of kaolin/PA6 systems. The rheological behavior of KH550 kaolin /PA6 system is different from that of KH560 kaolin/PA6 system, although chemical reactions have taken place between the surface of KH550 kaolin (or KH560 kaolin) and PA6 matrix during melt processing. This is attributable, in part, to the differences in the state of dispersion of kaolins in PA6 matrix and, to a great extent, to the differences in the extent of chemical reactions that have taken place between the filler and polymer matrix.     

聚合物结晶成核剂作用的表征方法的比较和研究

用聚合物的等速降温过程的结晶温度，等温结晶过程的半结晶时间（ｔ１／２）或结晶速度常数（Ｋ），结晶过程的晶核密度或球晶尺寸大小和聚合物结晶成核界面自由能（σσｅ或σｅ）大小等方法描述了碳酸钙、对苯二甲酸、苯甲酸钠对聚丙烯成核结晶过程的影响．通过对不同方法的比较，结果表明不同方法是从不同角度来反映助剂对聚合物成核结晶过程的影响，聚合物结晶温度的高低和等温结晶过程的半结晶时间或结晶速度常数是描述聚合物整体结晶速度的参数；而聚合物结晶过程中晶核密度或结晶完了时聚合物球晶尺寸，和聚合物结晶成核界面自由能大小与聚合物的成核难易程度直接相关，是判断聚合物结晶成核速度的方法．但不同方法之间存在一定的相关性，所以用不同方法测定的结果之间有较好的可比性，可根据具体条件选用一种方法．多种方法的配合使用可以较全面的了解成核剂的作用．     

EFFECTS OF SOLAR AND ARTIFICIAL UV IRRADIATION ON MOTILITY AND PHOTOTAXIS IN THE FLAGELLATE, Euglena gracilis

The effect of solar irradiation on the percentage of motile cells, their average speed and their phototactic orientation to white actinic light was studied in the flagellate, Euglena gracilis. Unfiltered solar radiation in midsummer during mid-day at a location near Lisboa, Portugal, was found to impair motility within 2 h. This effect is exclusively due to the UV-B component of the radiation and not due to UV-A, visible light or a temperature increase. Likewise, phototactic orientation was drastically impaired. Reduction of the solar UV-B irradiation by insertion of an ozone-Hooded plexiglass cuvette partially reduced the inhibition and covering the cuvettes with glass prevented any decrease in motility and photoorientation. Similar results were found with artificial irradiation (Xe lamps). After inoculation the motility of the population follows an optimum curve (optimum at 8 days). Also, the UV-B effect on motility was smallest after about one week and increased for younger and older cultures.     

AN EVALUATION OF CHARGE EFFECTS ON THE QUENCHING OF TRYPTOPHAN FLUORESCENCE IN SMALL PEPTIDES BY IODIDE ION

Abstract— Charge effects on the quenching of tryptophan fluorescence in small peptides by iodide ion have been analyzed by the conventional "static" quenching model and by a recently proposed competitive quenching model. The former involves a fit of the quenching data using two quenching parameters—one for dynamic and one for static quenching contributions. The latter model involves a single parameter fit in which the fitting parameter is the characteristic rate constant for quenching of the fluorescent state. Both models indicate a clear charge effect on the efficiency of quenching by iodide ion. However, the static model results are obscured by the interdependence of the two fitting parameters and the fact that the true physical meaning of the static parameter is uncertain. Rate constants derived from the competitive model can be converted into relative quenching efficiencies. These efficiencies, which vary by more than a factor of two for the molecules studied, are greatest when the positive charge is on the tryptophan and least when this residue contains a negative charge.     

THE EFFECTS OF THROMBOXANE INHIBITORS ON THE MICROVASCULAR AND TUMOR RESPONSE TO PHOTODYNAMIC THERAPY

Abstract— Vascular stasis and tissue ischemia are known to cause tumor cell death in several experimental models after photodynamic therapy (PDT); however, the mechanisms leading to this damage remain unclear. Because previous studies indicated that thromboxane release is implicated in vessel damage, we further examined the role of throm-boxane in PDT. Rats bearing chondrosarcoma were injected with 25 mg/kg Photofrin® (intravenously) 24 h before treatment. Light (135 J/cm ² , 630 nm) was delivered to thc tumor area after injection of one of the following inhibitors: (1) R68070: a thromboxane synthetase inhibitor; (2) SQ-29548: a thromboxane receptor antagonist; and (3) Flunarizine: an inhibitor of platelet shape change. Systemic thromboxane levels were determined. Vessel constriction and leakage were evaluated by intravital microscopy. Tumor response was assessed after treatment. Thromboxane levels were decreased more than 50% with SQ-29548 as compared to controls. Thromboxane levels in animals given R68070 and Flunarizine remained at baseline levels. SQ-29548 and R68070 reduced vessel constriction compared to controls, while Flunarizine totally prevented vessel constriction. R68070 and SQ-29548 inhibited vessel permeability compared to PDT controls; Flunarizine did not. Animals given these inhibitors showed markedly reduced tumor cure. These results indicate that the release of thromboxane is linked to the vascular response in PDT.     

CdS-Ag2S混晶膜电极对络合剂的响应

本文选择了八种典型的有代表性的络合剂,分别观察了它们在CdS-Ag₂S混晶膜电极上的响应,并根据实验值和计算值的比较,探讨了与镉电极响应有关的络合平衡以及应用镉电极测定某些络合物常数的问题,指出了所研究的络合剂在镉电极测试中的实用意义.     

ON THE MECHANISM OF QUENCHING OF SINGLET OXYGEN IN SOLUTION

Abstract— Bimolecular rate constants for the quenching of singlet oxygen O*₂(¹Δ_g), have been obtained for several transition-metal complexes and for β-carotene. Laser photolysis experiments of aerated solutions, in which triplet anthracene is produced and quenched by oxygen, yielding singlet oxygen which then sensitizes absorption due to triplet carotene, firmly establishes diffusion-controlled energy transfer from singlet oxygen as the quenching mechanism in the case of β-carotene. The efficient quenching of singlet oxygen by two trans-planar Schiff-base Ni(II) complexes, which have low-lying triplet ligand-field states, most probably also occurs as a result of electronic energy transfer, since an analogous Pd(II) complex and ferrocene, which both have lowest-lying triplet states at higher energies than the O*₂(¹Δ_g), state, quench much less effectively.     

氧化剂对聚苯胺性质的影响

当过硫酸铵与苯胺的摩尔量之比为1∶1至2∶1时,化学合成的聚苯胺具有高的产率,电导率也较高,过多的过硫酸铵存在,使聚苯胺的电导率明显下降,这是由于它氧化了不同的中间体使产物不同,及聚苯胺被进一步氧化而造成的。各种强的氧化剂虽能提高电化学合成的聚苯胺的电极电位,但都使它的电导率和电化学活性显著降低,这仅是由于聚苯胺的进一步氧化所引起的。为了保持聚苯胺高的电化学活性,应避免它与强氧化剂共存。     

化学发光淬灭测定磺胺甲基异噁唑(SMZ)的研究

复方新诺明系磺胺甲基异噁唑(Sulfamethoxazole,简称SMZ)和甲氧苄氨嘧啶(Trime-thoprim,简称TMP)的复方制剂,用于抗脑膜炎球菌、肺炎球菌、溶血性链球菌及革蓝氏阴性杆菌,为临床广泛使用的磺胺类抗菌药物之一。药典规定用永停滴定法,重氮化外指示剂法进行含量测定。文献报道也有用三波长分光光度法、双波长法、吸收度比值法,核磁共振法等。本文根据SMZ的结构     

THE ROLE OF MICROSCOPIC AND MACROSCOPIC VISCOSITY ON THE TRIPLET-TRIPLET QUENCHING OF ANTHRACENE

Abstract— The interpretation of the viscosity dependence of anthracene triplet decay is shown to be complexed by the effects of the macroscopic and the microscopic viscosity of the system on the translational diffusion coefficient. The second order rate constant for the decay of the anthracene triplet as measured by flash photolysis is equal to 2.45plusmn;.30×10⁹1. mole^-1sec-¹ for nearly a one hundredfold change in the viscosity of cyclohexane-polyisobutylene solutions. The translational diffusion coefficient is unaffected by the presence of the polymer, and the local viscosity of the polymer solutions is identical to that of the pure solvent.     

成核剂对聚丙烯熔融行为的影响

成核剂对聚丙烯熔融行为的影响陈彦徐懋（中国科学院化学研究所高分子物理开放实验室北京１０００８０）关键词成核剂，聚丙烯，平衡熔点聚合物的熔融过程受分子量大小、分子量分布、分子链构型（等规度、分子结构单元的键接序列）、不同的结晶晶型、不同的热历史等...     

几种螯合剂解镍致小鼠胰脏毒作用比较

小鼠腹腔注射氯化镍溶液(5 mg Ni/kg)染毒，观察了N-苯甲基-D-葡糖氨基二硫代甲酸钠(BGD)、二乙氨基二硫代甲酸钠(DDTC)、二羟乙氨基二硫代甲酸钠(DHED)及meso-2，3-二巯基丁二酸钠(DMSA)等螯合剂对镍致小鼠胰脏毒性的解毒作用。镍染毒后引起小鼠胰脏胰蛋白酶活性升高和羧肽酶A活性降低以及组织中镍、钙、锌浓度增加；镍染毒30 min和24 h后进行各螯合剂治疗(剂量均为400 μmol/kg)，BGD、DDTC和DMSA可明显抑制上述变化，其中BGD解镍毒效果最好、自身毒性最小、对镍致小鼠胰脏毒性有更好的解毒作用。     

Na+/K+ TRANSPORT AND PHOTOSENSITIVITY OF THE COLORLESS FLAGELLATE Peranema trichophorum (Euglenida)

Abstract— Perimycin, ouabain and elevation of extracellular K⁺ concentrations cause an increase in the fluence rate thresholds (white light) for the step-up photophobic response in Peranema trichophorum . Elevation of extracellular Na⁺ concentration decreases the thresholds for this response in comparison to the control level. The fluence rate threshold of perimycin-treated cells increases before the side effect of an antibiotic action appears. Removal of K⁺ ions from the medium of K⁺-treated cells to a concentration of 1 mM depresses the threshold for the step-up response to the control level. By addition of K⁺ or Na ⁺ ions to perimycin- or ouabain-treated cells the threshold returns to the control value. It is suggested that the flagellar and cell membrane are responsible for changes of P. trichophorum photosensitivity.     

MICELLAR EFFECT ON THE FLUORESCENCE QUENCHING OF INDOLIC COMPOUNDS BY AMINOACIDS

Abstract— The photolysis in aqueous neutral solutions of 5-nitrofurfural (NFA), an important metabolite of nitrofurans used as medicines, was investigated. Upon UV-A irradiation NFA loses up to 70 mol % nitrite, with formation of 5-hydroxymethylene-2(5H)-furanone, a new substance. When Cl⁻¹ is present 5-chlorofurfural is an important photoproduct. Photo-induced addition of either OH or CI⁻¹, followed by thermochemical elimination of NO₂⁻¹, is the proposed mechanism. Furthermore, NFA reacts with nitrite yielding nifuroxim. The possible role of the NFA photolysis in the occurrence of (photo)biological effects of NFA is discussed.     

EFFECTS OF INORGANIC NITROGEN ON THE RESPONSE OF LEMNA CARBON DIOXIDE OUTPUT TO LIGHT QUALITY AND TIMING*

Abstract —The effects of various light/dark schedules on the time course of CO₂ output by axenic cultures of the short-day plant Lemna perpusilla 6746 differ substantially depending on whether the medium is N-less or contains NH₄ or NO₃ as the sole N source. The steady-state pattern achieved with a daily 1/4 h light pulse in N-less medium is essentially the same whether the light is red or far-red; on NO₃ or NH₄, however, the red and far-red patterns differ in form and suggest the action of a ‘Pfr-hourglass’ timer. In darkness, following either continuous light or entrainment to kh red light daily, CO₂ output oscillates for three or more circadian cycles on NH₄ medium and for at least two on N-less, but damps after a single cycle on NO₃. A schedule of 1/4 h red light every 12 h elicits a 24 h periodicity on NO₃ or NH₄ media and a 12 h periodicity on N-less medium, while a similar far-red schedule elicits a 12 h periodicity on all three. CO₂ output patterns on each of the media respond differently to varying the daily span of light from 1/4 to 6 to 12 h. These results are probably due to differential effects of changing N status on the proportion of total C O₂ arising from various metabolic reactions. They suggest that, rather than being a simple, unitary indicator, CO₂ output can be made to reflect different processes on different media, increasing its value as a real-time indicator of events underlying photoperiodism.     

ON THE QUENCHING OF SINGLET OXYGEN BY α-TOCOPHEROL

Abstract —D-α-tocopherol was found to be an effective quencher of ¹O₂ molecules ( k = 2.5 times 10⁸→mol^-1 s^-1 in pyridine) by measuring its effect on the autosensitized photooxidation of rubrene. The quenching process was shown to be almost entirely 'physical', that is, α-tocopherol deactivated about 120 ¹O₂ molecules before being destroyed. The results suggest that this process may be a mechanism for the protective effect of α - tocopherol in photodynamic action.     

INVESTIGATIONS ON THE FLUORESCENCE CONCENTRATION QUENCHING OF FLAVOMONONUCLEOTIDE IN GLYCERINE-WATER SOLUTIONS

We measured concentration changes of the fluorescence quantum yield eta/eta 0 of flavomononucleotide (FMN) in glycerine-water solutions of various viscosities. The results obtained show that FMN dimers are traps for the exciting light energy as well as the energy transferred non-radiatively. Very good agreement between the experimental and theoretical eta/eta 0 results was obtained. It has been shown that in the investigated solutions non-radiative energy transfer from monomers to dimers takes place, preceded by the migration of energy. It has been stated that no monomer quenching occurs in these solutions. The contribution of the individual fluorescence concentration quenching mechanisms has been determined.