萜烯树指及其在压敏胶粘剂中的应用

本文对萜烯树脂生产和研究的基本情况及在压敏胶中的应用作了综述性报道     

Effects of irbesartan and perindopril on pressure overload-induced cardiac hypertrophy in rats

AIM: To observe the effects of irbesartan and perindopril on pressure-overload cardiac hypertrophy in rats. METHODS: 40 male adult Sprague Dawley rats were divided into 5 groups. One was sham operation group, other four were aortic banding groups. One week after operation, all rats were gavaged with normal saline, perindopril, irbesartan or combination of perindopril and irbesartan. Morphometric determination, calcineurin (CaN) expression, CaN and sarcoplasmic reticulum (SR) Ca²⁺-ATPase activity were performed at the end of 6 weeks of drug intervention. RESULTS: Left ventricular mass index (LVMI), transverse diameter of myocardical cell (TDM), CaN activity were remarkably decreased after drug intervention and this decrease was most remarkable in the combination group. SR Ca²⁺-ATPase activity increased after drug intervention, especially in the combination group. CaN expression in myocardium were remarkably decreased after drug intervention. LVMI was positively correlated with TDM and CaN, negatively correlated with SR Ca²⁺-ATPase. CONCLUSION: Both irbesartan and perindopril decrease CaN activity, increase SR Ca²⁺-ATPase activity and combination of them has synergic effects on regressing of ventricular hypertrophy.     

Carprofen and buprenorphine prevent hyperalgesia in a model of inflammatory pain in cats

A model of nociceptive threshold determination was developed for evaluation of NSAID analgesia in cats. In a crossover study, eight cats received carprofen (4 mg/kg), buprenorphine (0.01 mg/kg) or saline (0.3 ml) subcutaneously before intradermal kaolin injection on the antebrachium to induce mild inflammation. Pressure thresholds were measured at the injected site using blunt-ended pins advanced by manual inflation of a bladder within a bracelet. Bladder pressure was recorded as threshold (PT) at the behavioural end point. Baseline PT were recorded before kaolin injection (time 0). PT was measured at 2-10 h intervals for 52 h. PT below the lower 95% confidence interval (CI) of baseline values indicated hyperalgesia. After saline, hyperalgesia was detected from 2-6 h, 22-26 h, and at 30 and 36 h. After carprofen, PT remained within the 95% CI. After buprenorphine, PT remained within the 95% CI except at 2h. Carprofen and to some extent buprenorphine, prevented inflammatory hyperalgesia.     

The influence of the width of the saddle tree on the forces and the pressure distribution under the saddle

As there is no statistical evidence that saddle fit influences the load exerted on a horse's back, this study was performed to assess the hypothesis that the width of the tree significantly alters the pressure distribution on the back beneath the saddle. Nineteen sound horses were ridden at walk and trot on a treadmill with three saddles differing only in tree width. Kinetic data were recorded by a sensor mat. A minimum of 14 motion cycles were used in each trial. The saddles were classified into four groups depending on fit. For each horse, the saddle with the lowest overall force (LOF) was determined. Saddles were classified as "too-narrow" if they were one size (2 cm) narrower than the LOF saddle, and "too-wide" if they were one size (2 cm) wider than the LOF saddle. Saddles two sizes wider than LOF saddles were classified as "very-wide". In the group of narrow saddles, the pressure in the caudal third (walk 0.63 N/cm(2)+/-0.10; trot 1.08 N/cm(2)+/-0.26) was significantly higher compared to the LOF saddles (walk 0.50 N/cm(2)+/-0.09; trot 0.86 N/cm(2)+/-0.28). In the middle transversal third, the pressure of the wide saddles (walk 0.73 N/cm(2)+/-0.06; trot 1.52 N/cm(2)+/-0.19) and very-wide saddles (walk 0.77 N/cm(2)+/-0.06; trot 1.57 N/cm(2)+/-0.19) was significantly higher compared to LOF saddles (walk 0.65 N/cm(2)+/-0.10/ 0.63 N/cm(2)+/-0.11; trot 1.33 N/cm(2)+/-0.22/1.27 N/cm(2)+/-0.20). This study demonstrates that the load under poorly fitting saddles is distributed over a smaller area than under properly fitting saddles, leading to potentially harmful pressures peaks.     

Calculation models of pressure and position of curved laminated veneer lumber in molds during pressing

Curved laminated veneer lumber (LVL) for use in furniture-making was produced from glue-coated pieces of rotary-cut veneers that were assembled and pressed between molds. Pressure was applied until glue-lines were set and finally held in an assembly of the desired curvature. Pressure was an important factor during pressing of curved LVL. In this study we deduced some equations for designing the shape of molds and calculating the total pressure from the mechanics. The results are summarized as follows: (1) The position angle of every section of curved LVL assembly in molds on the horizontal and the total pressure during pressing can be calculated in relation to the shapes and dimensions of the curved LVL. (2) The pressure distributions in the glue-line measured using pressure-sensitive film were in good agreement with the glue-line unit pressure provided for the experiment and calculation. Therefore, the equations deduced in this study were suitable for calculating the position angle and pressure of curved LVL in molds. (3) The total pressure on curved LVL was greater than the pressure on straight LVL. The total pressure consisted of the pressure on the glue-lines of straight LVL with the same length and width as curved LVL plus the supplementary pressure needed to bend the veneers. (4) The total pressures and position angles of curved LVL in molds were affected by the shape, bent angle, and length of each section of curved LVL.The outline of this study was presented at the 48th annual meeting of the Japan Wood Research Society, Shizuoka, April 3, 1998     

一次中尺度带状暴雨机制分析

利用地面加密观测资料、常规探测资料和NCEP 1°×1°再分析资料等,从环流形势入手,通过对水汽通量、假相当位温、24 h变温、地面风场、湿焓和压能场等的诊断分析,研究此次暴雨过程的形成机制。结果表明,此次暴雨是在高层槽前和中低层切变南侧的西南气流中产生的;低空西南急流和低层西南风辐合为暴雨提供了充足的水汽,低层涡旋的辐合提供了垂直上升的动力,低层海上回流的冷空气是暴雨产生最直接的促发机制。高压能舌与等湿焓密集带呈带状,且走向一致,强湿焓平流出现时间比实际出现强降水的时间早。冷空气激发带状θse锋区能量释放,东北—西南向的强湿焓平流促使带状强对流的发生,闽东南部900~700 h Pa水汽通道畅通,但低层水汽不足,故仅在700 h Pa水汽通量高值中心形成暴雨,闽西北水汽匮乏,直接导致其未出现强降水。     

静压活鱼提升设备实用性能参数测试

根据静压活鱼提升设备的适用范围及实用性能参数进行性能测试,并根据测得的流量,流速,时间与压力确定出设备的主要性能指标,试验表明：静压活鱼提升设备的流量与流速达到实际要求;提升最大鱼个体为（体重2kg,体长450mm);对鱼无损伤,鱼损率为零;最佳鱼水比为1：1。     

不同棚架结构对江西设施葡萄种植影响分析

对江西目前葡萄设施栽培中常用的简易“V”型种植篱架棚、“V”型种植连栋棚架、“平网”种植连栋拱顶棚架、“飞鸟”型种植连栋棚架的结构、造价进行分析,结合风、雪、葡萄攀爬果实等对四种棚架的承压影响,以及棚架结构对光照、温度等栽培环境的影响,进行了测试分析。结果表明,“平网”种植连栋拱顶棚架较其他三种成本高,但抗压能力强,维修成本少,通风性能好,适宜机械化操作,综合效益最佳。     

基于支持向量机的CVT压力传感器误差补偿

针对无级变速器(CVT)压力传感器测量误差较大的问题,提出了一种应用支持向量机(SVM)建立误差补偿模型的方法.在分析引起测量误差因素的基础上,确立了误差补偿模型的输入、输出基本结构;通过试验构建训练样本集,并完成误差补偿模型的训练,在训练过程中,通过遗传算法对模型参数进行了优化.试验结果表明,设计的误差补偿模型可以有效提高传感器的线性度,并可以把最大绝对误差从0.5 MPa降至0.15 MPa,显著提高了压力传感器的性能和测量精度.     

电控柴油机共轨管长径比对压力波动的影响

现代电控柴油机中共轨内压力的瞬态波动会直接影响到燃油喷射系统的喷油量的均衡。本文采用ASW软件建立了燃油喷射系统模型,设定平均压力波动量、试验商值和瞬态压力波动率3个参数,分析了高压共轨系统共轨管的容积、压力和长径比对共轨内压力波动产生的影响。