Radiation patterns of dual concentric conductor microstrip antennas for superficial hyperthermia

The finite difference time domain (FDTD) method has been used to calculate electromagnetic radiation patterns from 915-MHz dual concentric conductor (DCC) microwave antennas that are constructed from thin and flexible printed circuit board (PCB) materials. Radiated field distributions are calculated in homogeneous lossy muscle tissue loads located under variable thickness coupling bolus layers. This effort extends the results of previous investigations to consider more realistic applicator configurations with smaller 2-cm-square apertures and different coupling bolus materials and thicknesses, as well as various spacings of multiple-element arrays. Results are given for practical applicator designs with microstrip feedlines etched on the backside of the PCB antenna array instead of previously tested bulky coaxial-cable feedline connections to each radiating aperture. The results demonstrate that for an optimum coupling bolus thickness of 2.5-5 mm, the thin, flexible, and lightweight DCC antennas produce effective heating to the periphery of each aperture to a depth of approximately 1 cm, and may be combined into arrays for uniform heating of large area superficial tissue regions with the 50% power deposition contour conforming closely to the outer perimeter of the array.     

Effect of abortion on obstetric patterns

The statement of A.F. Pentecost that "it is an established fact that 1 or more terminations of pregnancy are liable to result in more women coming in at 26 weeks with ruptured membranes" needs to be challenged. The study he quotes to support his view indicates that 7 out of 8 women who had premature rupture of the membranes had previously been aborted of pregnancies exceeding 10 weeks' gestation and most likely with the traumatic techniques in use at that time. In the 1960s Hegar dilators of larger than Size 12 were used in the majority of cases, and dilation to such a degree was likely to result in frequent damage to the internal os, causing subsequent cervical incompetence and premature rupture of the membranes. However, the modern aspiration techniques now in use rarely require the cervix to be dilated to more than Hegar 10. Consequently, subsequent premature labor because of cervical incompetence is unlikely. Evidence is frequently quoted from a number of papers in support of Mr. Pentecost's position. It does not seem possible that a clinical trial will ever be conducted that will finally resolve the issue because of the problem of obtaining matched controls, difficulties of follow-up, and variable abortion techniques. Available evidence does indicate that modern legal abortion generally increases the risks of prematurity in a subsequent pregnancy. The remaining question is whether the reduction in the incidence of low birth weight can be ascribed to legal abortion.     

Effect of dielectric gaps on the conductance of resistance composites

Conclusions Mathematical expressions are given describing the contact resistance of the dielectric gaps in resistance composites and its temperature dependence. It is shown that thermally stable composites can be obtained by ensuring that the thermally induced changes in the resistance of their conducting particles are counter balanced by those of their gaps. Theoretical relationships between the CTE of the binder and conducting components are established which are necessary for the formulation of thermally compensated systems.Translated from Poroshkovaya Metallurgiya, No. 4(208), pp. 85–89, April, 1980.     

Effect of dietary patterns on measures of lipid peroxidation: results from a randomized clinical trial

BACKGROUND: Free radical-mediated oxidative damage to lipids is thought to be an important process in the pathogenesis of atherosclerosis. Although previous studies have demonstrated a beneficial impact of antioxidant vitamin supplements on lipid peroxidation, the effect of dietary patterns on lipid peroxidation is unknown. METHODS AND RESULTS: During the 3-week run-in period of a randomized trial, 123 healthy individuals were fed a control diet, low in fruits, vegetables, and dairy products, with 37% of calories from fat. Participants were then randomized to consume for 8 weeks: (1) the control diet, (2) a diet rich in fruits and vegetables but otherwise similar to the control diet, and (3) a combination diet rich in fruits, vegetables, and low-fat dairy products and reduced in fat. Serum oxygen radical-absorbing capacity, malondialdehyde (an in vitro measure of lipid peroxidation), and breath ethane (an in vivo measure of lipid peroxidation) were measured at the end of run-in and intervention periods. Between run-in and intervention, mean (95% CI) change in oxygen radical-absorbing capacity (U/mL) was -35 (-93, 13) in the control diet, 26 (-15, 67) in the fruits and vegetables diet (P=0.06 compared with control), and 19 (-22, 54) in the combination diet (P=0.10 compared with control). Median (interquartile range) change in ethane was 0.84 (0.10, 1.59) in the control diet, 0.02 (-0.61, 0.83) in the fruits and vegetables diet (P=0.04 compared with control), and -1.00 (-1.97, 0.25) in the combination diet (P=0.005 compared with control). Change in malondialdehyde did not differ between diets. CONCLUSIONS: This study demonstrates that modification of diet can favorably affect serum antioxidant capacity and protect against lipid peroxidation.     

Effect of regimes involving small loads on the tribological characteristics of self-lubricating slide bearings obtained from porous bronze containing antifriction additives

Translated from Poroshkovaya Metallurgiya, No. 12 (360), pp. 77–82, December, 1992.     

Effect of prenatal haloperidol administration on anxiety patterns in rats

Haloperidol (0.1 mg/kg, i.p.) treatment was given from day 12 to 20 of gestation to pregnant rats, this being the critical period for neural development in this species. The pups born were subjected to open-field exploratory behaviour, tunnel-board exploratory behaviour, elevated zero-maze and elevated plus maze behaviour tests at 7-8 weeks of age. The results indicate that prenatal haloperidol treatment induces a significant increase in open-field ambulations and rearings, decrease in scratching and licking/washing behaviours whereas grooming and faecal droppings remain unchanged. Significantly reduced activity in the centre and increased activity in the periphery of the tunnel board was noted. These suggest presence of anxiety in these animals. Significant anxiogenic behavioural patterns were also observed on elevated zero-maze and plus-maze in the prenatally haloperidol treated offsprings. The results suggest that prenatal exposure of haloperidol leaves a lasting effect on offsprings resulting in hyper-emotional responsiveness and anxiety state.     

退火工艺对Nb-V微合金化双相钢组织性能的影响

为了进一步提升双相钢性能、探究Nb-V元素复合添加对双相钢组织性能的影响,在实验室研发了Nb-V微合金化的冷轧双相钢。利用连退模拟试验机、扫描电镜等设备,系统地研究了退火温度和过时效温度对双相钢组织性能的影响。结果表明,抗拉强度和伸长率随着退火温度的升高变化不大,屈服强度在组织中铁素体含量明显减少后有显著提升;Nb、V元素的添加细化了组织,可以提高综合性能。随着过时效温度的升高,试验钢主要组织由起初低温时的淬火马氏体+回火马氏体变为高温时的粒状贝氏体,残余奥氏体比例也逐渐增大。高温过时效时,试验钢强度的降低主要由回火马氏体的软化造成;低温过时效时,V析出量的增加也对试验钢的强化起到了重要作用。     

Effect of thermomechanical treatment on structure and mechanical properties of Mo-bearing dual phase steel

The effects of hot rolling of a dual phase steel in the (α + γ) range on microstructure and mechanical properties was investigated by using two thermomechanical (TMT) routes. The first consisted of heating A_c3, soaking, cooling to deformation temperature in the (α + γ) range. The second comprises heating to deformation temperature in the (α + γ) range, followed by rolling and quenching. Parameters varied were temperature (with the first route) and extent of deformation (with the second). The microstructures were characterised by optical and transmission electron microscopy. The results indicate a distinct difference in the final structure and properties due to the two different TMT routes. The first TMT route resulted in a greater amount of ferrite, finer lath width of martensite, finer ferrite grain size and increased density of dislocations. The strength properties decreased, the YS/UTS ratio decreased and ductility increased with the increase in the extent and temperature of deformation. However, TMT route 2 resulted in an increase in the amount of martensite, finer ferrite grain size, decrease in the martensite lath width and increased dislocation density. The strength properties increased, YS/UTS ratio increased and ductility decreased with increase in the extent and temperature of deformation.     

Effect of contrast on the perception of moving multiple Gabor patterns

The present study examined the way in which the perception of motion coherency depends on luminance contrast. Pseudo-plaid patterns were presented to subjects who judged whether coherent motion or component motion of the Gabor patterns was perceived. Michelson contrast, eccentricity, spatial separation, and angular separation between two groups of Gabor patches were varied systematically. When the contrast was high, coherent motion perception was dominant in peripheral viewing but not in foveal viewing. When the contrast was low, coherent motion was perceived at all eccentricities. Under low-contrast conditions and with peripheral viewing, coherent motion was perceived over broader spatial areas and at wider angular separations. The contrast dependency of motion coherency can be qualitatively explained in terms of the relative activity of hypothetical local-motion units in area V1 and global-motion units in area MT of the visual cortex.     

锶锆共掺杂对钛酸钡陶瓷结构和介电性质的影响

采用固相反应法制备了(Ba0.85 Sr0.15)(Ti1-xZrx)O3(x=0.10,0.15,0.20,0.25)陶瓷.通过X射线粉末衍射、介电温谱测试和电子顺磁共振技术对其进行了结构表征、介电性能评价和杂质定性检测.结果表明:(Ba0.85 Sr0.15)(Ti1-xZrx)O3陶瓷显示平均立方钙钛矿结构,随着Zr掺杂量的增加,晶格常数和单胞体积线性增加;介电居里峰以-5.6℃的速率向低温线性移动,(Ba0.85 Sr0.15)(Ti0.8 Zr0.2)O3陶瓷的介电峰值超过8 000,并发生在室温附近,扩散系数γ=1.90,材料实现Y5V介电指标;除Sr/Zr双位替代效应导致介电峰更加扩散外,Fe和Mn杂质在Ti位的存在也是实现Y5V介电指标的主要原因之一.