水性聚氨酯荧光增白材料的合成及其性能研究

荧光增白剂可吸收不可见的紫外光,并且将紫外光转变为可见的蓝色或蓝紫色光发射出来;由于蓝色和黄色互为补色,消除了物质中的黄色部分,从而达到了增白效果。因此,采用荧光增白剂合成的水性聚氨酯(WPU)增白材料,用于涂料和织物上,可初步解决芳香族WPU的耐黄变问题。研究了乳液pH值、荧光增白剂的用量及其添加方式对WPU增白效果的影响,并通过透射电镜(TEM)观察增白剂在WPU中的分散情况。实验结果表明,WPU乳液及其胶膜的蓝光效果随着荧光增白剂用量的增加呈先增后降的趋势,当w(荧光增白剂)=0.008%时为最佳;当pH=7～9时,荧光增白剂在WPU中的分散稳定性和增白效果都较好;荧光增白剂的两种添加方式对其在WPU乳液及其胶膜中的分散稳定性和增白效果的影响不明显。     

Rating scales for the psychosocial evaluation of organ transplant candidates. Comparison of the PACT and TERS with bone marrow transplant patients

Two scaled formats for summarizing the results of psychosocial evaluations of transplant candidates have been published, the Psychosocial Assessment of Candidates for Transplantation (PACT) and the Transplant Evaluation Rating Scale (TERS). In this study, 40 consecutive candidates for bone marrow transplant were rated on the PACT and TERS. The PACT and TERS were comparable in interrater reliability. Similar conceptual items for each scale correlated fairly highly with one another. The PACT and TERS differ in several scale characteristics. The authors discuss the relationship between scale characteristics and clinical utility.     

Physiologic variations in lower extremity venous valvular function

We conducted this study to investigate the physiologic variations in venous valvular function and calf muscle pump function that occur in normal limbs after prolonged stationary standing. Twenty-two limbs from 11 healthy volunteers were studied after a brief period of activity and after 4 to 6 hours of stationary standing. Vein diameter, peak reflux flow velocity (PRFV), and valve closure time (VCT) were measured with duplex scanning in the standing position in the common femoral vein (CFV), superficial femoral vein (SFV), popliteal vein (POP), proximal greater saphenous vein (GSV), and greater saphenous vein at the knee (kGSV). Pneumatic rapid inflation-deflation cuffs were used to elicit reflux. Vein cross-sectional area (VA) and peak reflux volume (PRVol) were calculated. Venous volume (VV), venous filling index (VFI), ejection fraction (EF), residual volume fraction (RVF), and outflow fraction (OF) were measured with air plethysmography in all limbs. After stationary standing, there was no significant change or trend toward an increase in diameter or VA in any of the deep veins and there was no change in the PRFV or VCT. In the proximal GSV there was a significant increase in diameter (p = 0.0001) and VCT (p = 0.048) without a change in PRFV. No significant changes were noted in the kGSV. In the GSV the PRFV was significantly lower (p < 0.05) and the VCT significantly shorter (p < 0.05) compared with the SFV and POP but values were no different from those in the CFV. The PRFV was significantly higher in the SFV (p < 0.0001) and the POP (p < 0.002) compared with that in the CFV.(ABSTRACT TRUNCATED AT 250 WORDS)     

球铁材料脉冲激光表面强化的实验研究

采用经过二元光学变换后呈二维点阵分布的脉冲激光束对球铁试样作了表面强化处理。对强化前后试样表面的粗糙度、强化层深度、强化层显微硬度分布和耐磨性进行了研究。结果表明,在保证试样表面粗糙度(表面微熔或不熔)的前提下,随脉宽增加强化区层深增加。耐磨性测试表明,脉冲激光强化处理可提高材料耐磨性1.8倍以上。     

药厂净化空调系统几个问题的探讨

对药厂净化空调系统中的组合式空调箱功能段、消声器、回风口过滤器及双风机系统等几个方面的问题,从理论和实践方面进行了论述和分析,提出了自己的观点。并对有关规范的某些条文提出了自己的看法。     

Effective targeting of magnetic radioactive 90Y-microspheres to tumor cells by an externally applied magnetic field. Preliminary in vitro and in vivo results

Magnetic biodegradable poly(lactic acid) microspheres that incorporate both magnetite and the beta-emitter 90Y were prepared. By applying a directional external magnetic field gradient in excess of 0.02 Tesla/cm across a 96-well plate containing neuroblastoma cells incubated with the 90Y magnetite loaded microspheres, the radiation dose to the cells could be enhanced or reduced relative to the dose from a uniform loading of the well with 90Y-DTPA. Using the MTT assay, cell survival was measured for the magnetic field directed from above (cell sparing) and from below (cell targeting) the well plate, resulting in 65 +/- 8% or 18 +/- 5% survival respectively. This method was then applied to an in vivo murine tumor model. The biodistribution of intraperitoneally injected magnetic radioactive microspheres, after 24 h in mice, showed that 73 +/- 32% of the radioactivity was found on the subcutaneous tumor that had a rare earth magnet fixed above it. In contrast, the tumor radioactivity with no attached magnet was 6 +/- 4%. Magnetically targeted radiopolymers such as 90Y-microspheres show great promise for regional or intracavitary radiotherapy.     

Obliterative bronchiolitis after lung and heart-lung transplantation

Obliterative bronchiolitis (OB) has emerged as the main cause of morbidity and mortality in the long-term follow-up after lung and heart-lung transplantation. The pathogenesis of OB is multifactorial, with acute rejection and cytomegalovirus infection being the main risk factors for the development of OB. The final common pathway of all inciting events seems to be an alloimmune injury, with subsequent release of immunologic mediators and production of growth factors leading to luminal obliteration and fibrous scarring of the small airways. Analyzing the 14 years of experience in 163 patients at Stanford University, we found a current incidence of bronchiolitis obliterans syndrome or histologically proven OB within the first 3 years after lung and heart-lung transplantation of 36.3%, with an overall prevalence of 58.1% after heart-lung and 51.4% after lung transplantation. Both pulmonary function indices (forced expiratory flow between 25% and 75% of forced vital capacity and forced expiratory volume in 1 second) and transbronchial biopsies have proven helpful in diagnosing bronchiolitis obliterans syndrome or OB at an early stage. Early diagnosis of OB and improved management have achieved survival rates in patients with OB after 1, 3, 5, and 10 years of 83%, 66%, 46%, and 22%, compared with 86%, 83%, 67%, and 67% in patients without OB. Recently, different experimental models have been developed to investigate the cellular and molecular events leading to OB and to evaluate new treatment strategies for this complication, which currently limits the long-term success of heart-lung and lung transplantation.     

EC Directive on the Control of Dangerous Substances (76/464/EEC): Its Impact on the UK Water Industry

This paper discusses the impact on the UK water industry of EC legislation which has been adopted and proposed for the control of dangerous substances discharged to the aquatic environment. The main impact arises from the increased monitoring needs, requiring more sophisticated analytical equipment and skilled staff, together with the increased administrative burden to produce reduction programmes and to set and control consents for dangerous substances. The paper also summarizes recent initiatives which have been taken by the UK towards a more precautionary approach to pollution control, by requiring that 'red-list' substances should be controlled by environmental quality standards and limit values whichever are the more stringent.     

Glutathione S-transferase a major allergen of the house dust mite, Dermatophagoides pteronyssinus

Cutaneous electrogastrography (EGG) allows the measurement of gastric electrical activity. An association of EGG with gastrointestinal motility disorders has been shown. Abnormalities of electrical rate or rhythm are accepted as the most important parameters in EGG. However, the reliability of the magnitude of electrical amplitude in the assessment of motility is discussed controversially. Therefore in a prospective study we investigated the relation between amplitude and antral contractions by means of ultrasonography. 8 healthy volunteers (4 men, 4 women, 24-31 years) ingested 400 ml carbonated mineral water after an overnight fast at two separate study days. Over a period of 10 min preprandial and 10 min postprandial small and intense antral contractions were measured employing sagittal antral planimetry. Simultaneous amplitudes were determined during contractions and at 1 min intervals (average amplitude) by cutaneous electrogastrography. Data were analyzed by Wilcoxon's rank sum test and Spearman rank correlation test. The coefficient of variation of the postprandial/preprandial amplitude ratio was nearly two times greater between subjects than between recordings in the same subject, which reflects a moderate intraindividual reproducibility. We found a significant increase in the average amplitude postprandially (p < 0.05). Although postprandial contractions (n = 243) predominated preprandial contractions (n = 127) significantly (p = 0.02), no significant correlation between the number of contractions and the average amplitude existed (R = 0.1; p = 0.7). Moreover the average amplitude did not differ from amplitudes during intense and small contractions significantly (p = 0.7; p = 0.1). The magnitude of the amplitude measured by EGG does not correlate with the mechanical gastral activity significantly.(ABSTRACT TRUNCATED AT 250 WORDS)     

Direct voltammetric observation of redox driven changes in axial coordination and intramolecular rearrangement of the phenylalanine-82-histidine variant of yeast iso-1-cytochrome c

Direct square-wave and cyclic voltammetric electrochemical examination of the yeast iso-1-cytochrome c Phe82His/Cys102Ser variant revealed the intricacies of redox driven changes in axial coordination, concomitant with intramolecular rearrangement. Electrochemical methods are ideally suited for such a redox study, since they provide a direct and quantitative visualization of specific dynamic events. For the iso-1-cytochrome c Phe82His/Cys102Ser variant, square-wave voltammetry showed that the primary species in the reduced state is the Met80-Fe2+-His18 coordination form, while in the oxidized state the His82-Fe3+-His18 form predominates. The addition or removal of an electron to the appropriate form of this variant serves as a switch to a new molecular form of the cytochrome. Using the 2 x 2 electrochemical mechanism, simulations were done for the cyclic voltammetry experiments at different scan rates. These, in turn, provided relative rate constants for the intramolecular rearrangement/ligand exchange and the equilibrium redox potentials of the participating coordination forms: kb,AC = 17 s-1 for Met80-Fe3+-His18 --> His82-Fe3+-His18 and kf,BD > 10 s-1 for His82-Fe2+-His18 --> Met80-Fe2+-His18; E0' = 247 mV for Met80-Fe3+/2+-His18 couple, E0' = 47 mV for His82-Fe3+/2+-His18 couple, and E0' = 176 mV for the cross-reaction couple, His82-Fe3+-His18 + e- --> Met80-Fe2+-His18. Thermodynamic parameters, including the entropy of reaction, DeltaS0'Rxn, were determined for the net reduction/rearrangement reaction, His82-Fe3+-His18 + e- --> Met80-Fe2+-His18, and compared to those for wild-type cytochrome, Met80-Fe3+-His18 + e- --> Met80-Fe2+-His18. For the Phe82His variant mixed redox couple, DeltaS0'Rxn = -80 J/mol.K compared to DeltaS0'Rxn = -52 J/mol.K for the wild-type cyt c couple without rearrangement. Comparison of these entropies indicates that the oxidized His82-Fe3+-His18 form is highly disordered. It is proposed that this high level of disorder facilitates rapid rearrangement to Met80-Fe2+-His18 upon reduction.