Effects of salinity on egg and fecal pellet production, development and survival, adult sex ratio and total life span in the calanoid copepod, A cartia tonsa:a laboratory study

The ef fects of salinity on the copepod, A cartia tonsa in terms of daily egg production rate(EPR), hatching success, fecal pellet production rate(FPR), naupliar development time and survival, sex ratio, and total life span were determined in laboratory conditions through three experiments. In experiment 1, EPR, hatching success, and FPR of individual females were monitored at salinities of 13, 20, 35 and 45 during short-periods(seven consecutive days). Results show EPR was aff ected by salinity with the highest outputs recorded at 20 and 35, respectively, which were considerably higher than those at 13 and 45. Mean FPR was also higher in 35 and 20. In experiment 2, the same parameters were evaluated over total life span of females(long-term study). The best EPR and FPR were observed in 35, which was statistically higher than at 13 and 20. In experiment 3, survival rates of early nauplii until adult stage were lowest at a salinity of 13. The development time increased with increasing of salinity. Female percentage clearly decreased with increasing salinity. Higher female percentages(56.7% and 52.2%, respectively) were signifi cantly observed at two salinities of 13 and 20 compared to that at 35(25%). Total longevity of females was not af fected by salinity increment. Based on our results, for mass culture we recommend that a salinity of 35 be adopted due to higher reproductive performances, better feeding, and faster development of A. tonsa.

Fatigue reliability quantitative analysis of cement concrete for highway pavement under high stress ratio

In order to obtain the change law of the fatigue reliability of cement concrete for highway pavement under high stress ratios, first, the probability densities of monotonic random variables including concrete fatigue life are deduced. And then, the fatigue damage probability densities of the Miner and Chaboche-Zhao models are deduced. By virtue of laboratory fatigue test results, the fatigue damage probability density functions of the two models can be obtained, considering different stress ratios. Finally, substituting load cycles into them, the change law of cement concrete fatigue reliability about load cycles can be acquired. The results show that under the same stress ratio, with the increase in the load cycle, the fatigue reliability declines from almost 100% to 0% gradually. No matter under what stress ratio, during the initial stage of the load action, there is always a relatively stable phase for fatigue reliability. With the increase in the stress ratio, the stable phase gradually shortens and the load cycle corresponding to the reliability of 0% also decreases. In the descent phase of reliability, the higher the stress ratio is, the lower the concrete reliability is for the same load cycle. Besides, compared with the Chaboche-Zhao fatigue damage model, the Miner fatigue damage model is safer.

微囊藻毒素-LR完全抗原的设计及制备

从偶联位点、偶联剂、载体蛋白和偶联步骤等分析出发,设计了微囊藻毒素-LR (Microcystin- LR ,MC- LR)完全抗原的制备方法.在半抗原分子第7位氨基酸分子上引进1个自由的氨基;再用戊二醛2步法将此中间产物(H2 N etMC- LR)分别与BSA和OVA偶联.中间产物和偶联产物分别经固相萃取和透析纯化后,经SDS凝胶电泳、紫外扫描及生物质谱技术鉴定,结果表明MC- LR与BSA的平均偶联比能达到5以上,满足了进一步免疫的要求.

Fatigue Damage Calculated by the Ratio-Method to Materials and Its Machine Part

Several new calculating equations on the damage-evolving rate are suggested for describing the elastic-plastic behavior of some materials under un-symmetric cyclic loading. And the estimating formulas are given of the life relative to varied damage value D oi at each loading history. The method is to adopt the ratio of plastic strain range to elastic strain range as the stress-strain parameter, using the staple material constants as the material parameters in damage calculating expression. And it gives out a new concept of the compositive material constant, that has a functional relation with the staple material constants, average stress,average strain and critical loading time. In addition, it calculates fatigue damage as example for a part of car, its calculating results are accordant with the Landgraf’s equation, and calculating precision is more rigorous, so could avoid unnecessary fatigue tests and will be of practical significance to stint times, manpower and capitals, and to provide convenience for engineering applications.

Effects of Strain Ratio on Fatigue Behavior of G20Mn5QT Cast Steel

Due to traffic and wave actions, cast steel joints are subjected to variable-amplitude fatigue loading, which may cause fatigue problems. The ratio of the minimum strain to the maximum strain(strain ratio)can be employed to analyze the influence of variable-amplitude fatigue both in the elastic and plastic ranges. To evaluate the effect of the strain ratio on G20Mn5 QT cast steel, the fatigue tests of smooth specimens were carried out at the strain ratio of 0.1. The cyclic deformation and the relationships between the strain amplitude, the stress amplitude, the Smith, Watson and Topper(SWT)parameter and fatigue life were studied and compared with those at the strain ratio of-1. Compared with other methods, Basquin formula and Solonberg formula provide reliable and appropriate ranges of S-N curve and fatigue limit at different strain ratios respectively. The SWT parameter can be used to predict the fatigue life at other strain ratios accurately.

Effect of Notch Location on Fatigue Life Prediction of Strength Mismatched HSLA Steel Weldments

Welding of high strength low alloy steels (HSLA) involves usage of low, even and high strength filler materials (electrodes) than the parent material depending on the application of the welded structures and the availability of the filler material. In the present investigation, the fatigue crack growth behaviour of weld metal (WM) and heat affected zone (HAZ) regions of under matched (UM), equal matched (EM) and over matched (OM) joints has been studied. The base material used in this investigation is HSLA-80 steel of weldable grade. Shielded metal arc welding (SMAW) process has been used to fabricate the butt joints. Centre cracked tension (CCT) specimen has been used to evaluate the fatigue crack growth behaviour of the welded joints. Fatigue crack growth experiments have been conducted using servo hydraulic controlled fatigue testing machine at constant amplitude loading (R=0).A method has been proposed to predict the fatigue life of HSLA steel welds using fracture mechanics approach by incorporating influences of mismatch ratio (MMR) and notch location.

Early administration of branched-chain amino acid granules

The effect of malnutrition on survival in patients with decompensated liver cirrhosis has not been well defined. Nutritional intervention with branched-chain amino acid (BCAA) can increase serum albumin concentration in patients with decompensated cirrhosis but its effects on survival are unclear. The BCAA to tyrosine ratio (BTR) is a surrogate marker (the normal range of BTR is between 4.41 and 10.05, and a Fischer's ratio of 1.8 corresponds to a BTR of 3.5) in patients with decompensated liver cirrhosis, and BCAA inhibits hepatic carcinogenesis in patients with compensated cirrhosis. This review discusses data regarding the effect of early administration of BCAA granules based on the ratio of BCAA to BTR on prognosis in patients with cirrhosis.

LIFE CYCLE AND PRODUCTION OF CHIRONOMIDAE(DIPTERA) IN BIANDANTANG, A TYPICAL MACROPHYTIC LAKE (HUBEI, CHINA)

The life cycle and annual production of four dominant species of Chironomids ( Chironomus plumosus, Chironomus sp., Clinotanypus sp., Tokunagayusurika akamusi) were studied with samples taken monthly in Biandantang Lake at eight stations from April, 1996 to March, 1997. Instar frequency data showed C. plumosus was univoltine, while the other three were bivoltine. Production in wet weight (g/(m 2·a)) calculated by the size frequency method for each species were: C. plumosus, 2.663 ; Chironomus sp.,1.161 ;Clinotanypus sp., 0.270; T. akamusi , 1.476. Based on the mean standing stock, their P/B ratios were 3.2, 4.0, 6.2 and 4.4, respectively.

Factors Related to Functional Capacity and Quality of Life for Elderly People in a Middle-Sized City of São Paulo, Brazil

Introduction: It is a fact that the elderly population has been increasing all around the world and also in Brazil. This has been a challenge for governments and managers in the development of public policies to promote healthy and quality aging. And one of the conditions for healthy aging is to assess the functional capacity and quality of life of elderly people. Objective: The aim of the present study was to evaluate the factors that influence the loss of functional capacity and the worsening of the quality of life of a representative sample of elderly people from a medium-sized city in the inner of São Paulo State, Brazil. Methodology: Questionnaires about activities of daily living (ADL), instrumental activities of daily living (IADL), Flanagan quality of life scale (FQOLS), sociodemographic and morbidities aspects were applied to the elderly people. In order to assess associated factors to functional capacity and quality of life, chi-square tests and logistic regression models were fitted including variables: gender, age group, marital status, income, education level, body mass index, abdominal circumference and some morbidities reported by the elderly people. The level of significance adopted for the statistical tests was 5%. Results: Elderly with age over 75 years old and not married had more risk to be dependent on ADL, while elderly with more than 75 years old, not married, income below one minimal wage, cardiovascular disease and be diabetic had more risk to be dependent by IADL. Already, people with excess of weight had smallest risk to be dependent by IADL, paradoxically. The elderly not married and with an income below a minimum wage had the worst quality of life. Conclusions: Population aging in Brazil is an evident factor, so it is hoped that this study will contribute to the greatest diligence on the issues of the elderly and related social problems.

Effect of Strain Ratio on Fatigue Model of Ultra-fine Grained Pure Titanium

The ultra-fine grained(UFG)pure titanium was prepared by equal channel angular pressing(ECAP)and rotary swaging(RS).The strain controlled low cycle fatigue(LCF)test was carried out at room temperature.The fatigue life prediction model and mean stress relaxation model under asymmetrical stress load were discussed.The results show that the strain ratio has a significant effect on the low cycle fatigue performance of the UFG pure titanium,and the traditional Manson-coffin model can not accurately predict the fatigue life under asymmetric stress load.Therefore,the SWT mean stress correction model and three-parameter power curve model are proposed,and the test results are verified.The final research shows that the threeparameter power surface model has better representation.By studying the mean stress relaxation phenomenon under the condition of R≠-1,it is revealed that the stress ratio and the strain amplitude are the factors that significantly afiect the mean stress relaxation rate,and the mean stress relaxation model with the two variables is calculated to describe the mean stress relaxation phenomenon of the UFG pure titanium under different strain ratios.The fracture morphology of the samples was observed by SEM,and it was concluded that the final fracture zone of the fatigue fracture of the UFG pure titanium was a mixture of ductile fracture and quasi cleavage fracture.The toughness of the material increases with the increase of strain ratio at the same strain amplitude.

A Method of Determining Realistic Stress S/N Curves by Interpolations and Extrapolations of Two Known Best-Fit S/N Curves for Fatigue Life Predictions

The design and sizing of new mechanical components which are intended to operate under cyclic loads often require an acceptable level of confidence that the components will meet pre-defined fatigue strength objectives for crack initiation. For loads with multiple amplitudes and mean values, models based on Palmgren-Miner’s linear cumulative damage hypothesis and on multiple S/N curves (stress-no. cycles) are widely used in estimations for the duration of crack initiation. In this paper a procedure for generating S/N curves for multiple stress ratios by interpolation or extrapolation from the data available for two such curves is proposed. At any number of cycles, the stress for crack initiation is calculated from the far field macroscopic stresses of the known curves using Dang Van fatigue criterion and microscopic stresses evaluated at the grain level. An algorithm is presented for uniaxial loading and results verifications against curves established from laboratory tests with elastic and plastic stresses are shown and discussed for notched and un-notched specimens.

指纹证据似然比评价数据库的构建与评估

建立科学的指纹证据量化评价体系,尤其是将似然比统计学方法引入指纹鉴定意见的数字化表达,是当前法庭科学理论和实践研究的热点问题。构建科学有效的指纹证据似然比评价模型,需要丰富的同源和异源指纹数据库来获得具有稳定分布规律的似然函数,因而,同源和异源数据库的质量高低直接影响了似然比模型的性能优劣。本研究通过活体采集仪和录屏软件获取每枚指纹在不同变形方式下产生的1000枚以上变形指纹图像,200枚模拟现场指纹共得到20万枚同源指纹,进而构成同源指纹数据库;异源指纹数据库则选用公安实战中千万人级的十指指纹数据库。在此基础上,运用指纹自动识别系统进行查询比对,并评估比对得分数据。实验结果表明,不同变形方式的指纹数据差异较大;压力大小和捺印时间对指纹的比对得分影响很小。由对样本总量不同程度缩减后的子样本数据的统计分析结果可知,每枚指纹的同源样本数量在少至155枚时仍然能形成稳定的分布规律。因此,所构建的数据库中同源和异源指纹样本数量丰富,结构合理,具备形成稳定分布规律的数据基础,有助于后续似然比评价模型的建立。

浅析三带型基因座同一认定似然比的计算策略

目的探讨短串联重复序列(short tandem repeat,STR)三带型基因座同一认定似然比(likelihood ratio,LR)的不同计算策略。方法通过忽略三带型基因座、基于人群中不同类型的观测值、基于三带型基因座形成机制推导公式三个模型,对三带型基因座似然比进行计算。结果得到三个模型六种策略的LR计算方法,并分析其保守性与局限性。结论根据三体综合征发生机制推导的三带型基因座LR计算公式,可得到较为准确且可用于司法鉴定的LR值。

铝合金双面焊对接接头内部缺陷扩展行为分析

基于ABAQUS和FRANC3D联合仿真方法分析了铝合金双面焊对接接头中内部缺陷在疲劳荷载作用下的裂纹扩展行为。对比接头全模型中不同裂纹深度a下裂纹尖端应力强度因子K及疲劳寿命N,验证了对称模型的准确性,进而基于对称模型分析了不同形状比(深度a/长度2c)下初始缺陷的疲劳扩展规律。结果表明:当椭圆形缺陷的深度a不变而长度2c逐渐增大时,初始应力强度也随之增加,试件的疲劳寿命显著降低,当长轴长度增加3倍时,疲劳寿命降低了50%;随着裂纹的扩展,a/c的比值逐渐趋近于1,即形状趋近于圆形。

碳纤维增强复合材料疲劳寿命分析

为实现碳纤维增强复合材料疲劳寿命的便捷、高精度评估,开展了两种碳纤维增强树脂基复合材料在不同应力比下的疲劳试验研究,分析了不同应力比下的疲劳破坏过程和失效模式,提出了一种考虑应力水平和应力比的碳纤维增强复合材料疲劳寿命评估模型。通过两种材料的拉-压和压-压疲劳试验,验证了该模型的适用性。本文所建立的疲劳寿命评估模型预估寿命与试验寿命偏差小于2.5倍分散带。

圈养大熊猫种群性比失衡现象产生机制的探究

大熊猫(Ailuropoda melanoleuca)的迁地保护工作已开展了近70年,基本实现了圈养种群的自我维持。根据2019年大熊猫谱系,现存圈养大熊猫种群(n=612)的总性比为1.22∶1(♀336/♂276),与1∶1的性比有显著性差异(P=0.015),目前尚未开展性比失衡现象产生机制的探究工作。本研究以全国最大的圈养大熊猫种群为研究对象,梳理了该种群36年的出生性比、11年的分年龄雌雄个体数量和分年龄死亡雌雄个体数量,计算了出生性比和预期寿命等数据,旨在探究性比失衡的内在原因。结果显示,圈养大熊猫种群的出生性比为1.01∶1,与1∶1的性比无显著性差异(P=0.926);雄性大熊猫在幼年阶段死亡的比例高于雌性(♀38.24%/♂48.72%);圈养大熊猫的出生预期寿命中位数为21.4岁,其中雌性为23.5岁,雄性为19.8岁,雌性预期寿命比雄性长3.7岁。研究表明,圈养大熊猫种群性比失衡的内在原因是雄性大熊猫幼年阶段的死亡比例高于雌性,且雌性大熊猫预期寿命更长。本研究聚焦圈养大熊猫种群的性比失衡问题,首次计算了圈养大熊猫的预期寿命,可为圈养大熊猫种群的饲养管理和野外大熊猫种群性比问题的进一步研究提供参考。

磨牙区不同冠根比例种植体的动力学及疲劳分析研究

目的 探讨磨牙区种植体长度一致下,二期修复时产生的不同种植体冠根比例对种植体系统及周围骨的受力影响,从而获得磨牙区最适合冠根比值区间,为增加种植体临床寿命提供新思路。方法 通过三维有限元方法分析冠根比例为1∶1.5、1∶1、1.5∶1、2∶1、2.5∶1、3∶1的种植体系统的基台、中央螺丝、种植体、皮质骨和松质骨受力情况、疲劳寿命和安全系数。结果 在动态载荷作用力下,种植体构件和周围骨受力随冠根比例增加而增大。种植体系统应力集中在基台和种植体连接处。疲劳寿命和安全系数随着冠根比例增加而减小。结论 在种植体冠根比例大于1的情况下,基台-种植体连接处发生疲劳折断是种植体的潜在危险之一。冠根比例≤1时,种植体各构件可以获得良好的预后和远期效应。但由于有限元方法的特殊性,还有待临床进一步的深入研究。

不同颜色果袋套袋对宝岛蕉果实品质的影响

为了提高宝岛蕉果实商品性,开展蓝色(对照)、红色、黄色、透明聚乙烯(PE)果袋套袋处理,测定比较不同套袋处理的宝岛蕉果实色泽、果肉果皮硬度、货架期以及可溶性固形物含量等内在品质指标,并采用隶属函数法综合评价各处理。结果表明,透明PE袋、红色PE袋和黄色PE袋能显著提高青蕉果皮亮度。相比对照(蓝色PE袋),透明PE袋、红色PE袋和黄色PE袋均能显著提高熟蕉果皮硬度,黄色PE袋显著延长熟蕉果实货架期。相比其他处理,红色PE袋处理显著降低果实可溶性固形物含量,黄色PE袋降低果实总酸含量,且显著提高固酸比。综合评价发现黄色PE袋适宜作为宝岛蕉的套袋材料,可在生产上推广应用。

应力比对高强钢丝腐蚀疲劳寿命的影响研究

建立了高强钢丝腐蚀疲劳寿命模型,用于预测不同应力比和应力范围下的腐蚀疲劳寿命,研究应力比对腐蚀疲劳寿命的影响。利用应力比与应力范围之间的关系,处理了不同应力比和应力范围下高强钢丝腐蚀疲劳耦合试验数据。基于处理后的试验数据,对寿命模型进行参数估计,建立了高强钢丝腐蚀疲劳寿命模型,研究了不同应力比下腐蚀疲劳寿命的演化规律。结果表明:高强钢丝腐蚀疲劳寿命模型的预测值与试验数据吻合较好。该模型对高应力范围的腐蚀疲劳寿命预测值小于试验数据,对低应力范围的腐蚀疲劳寿命预测值大于试验数据。随着应力比的增大,高强钢丝的S-N曲线逐渐左移,而且斜率的绝对值逐渐变小。高强钢丝的腐蚀疲劳寿命随应力比的增大而减小。当应力比较大时,应力范围对腐蚀疲劳寿命的影响减小。应力比对低应力范围下的腐蚀疲劳寿命影响更显著。

美藤果油微胶囊包埋工艺优化及抗疲劳作用研究

目的优化美藤果油微胶囊的制备工艺,并探讨其抗疲劳功效。方法以美藤果油为芯材,以大豆分离蛋白、麦芽糊精为壁材,利用喷雾干燥法制备美藤果油微胶囊,并优化工艺参数,采用Schaal烘箱法进行加速氧化实验,并根据Van’t Hoff经验预测美藤果油微胶囊货架期;设置对照组、美藤果油组、微胶囊组,通过负重游泳实验及检测相关生化指标考察美藤果油及其微胶囊的抗疲劳作用。结果大豆分离蛋白:麦芽糊精质量为2:1时,微胶囊外观颗粒完整,呈规则圆形,包埋效果较好,最佳的工艺参数为进风温度:173℃、芯壁比:1:4、乳化剂用量:1.5%,包埋率为93.8%,与预测值较接近,加速氧化实验表明微胶囊化能够有效延长美藤果油保质期达608d;与对组相比,美藤果油及其微胶囊能够延长负重游泳时间,减少血清尿素氮、血乳酸的积累,增加机体肌糖原、肝糖原水平,提升运动持久性,减少疲劳。结论美藤果油的包埋效果良好,微胶囊化有利于提高其氧化稳定性,并且具有明显的抗疲劳功效。