纤维长度因素

已经证实,转杯纱中的纤维分布和形态与环锭纱不同。J.Kasparek借助纤维有效长度分布这一概念,把纱线不匀率与纱线内部结构联系起来,发现转杯纱的纤维纺入系数比环锭纱低。

含外伸桁架和斜拉杆的立柱屈曲分析

通过对某工程起重机立柱可能失稳方向的分析,建立了含外伸桁架和斜拉杆的立柱屈曲分析的简化模型,并在此基础上,推导了立柱的屈曲基本方程。数值算例验证了方法的正确性,计算了桁架的最优长度并探讨了其影响因素,得到此类立柱的最小长度因数为2/3的结论。

动力舱出风口分布式管式气压测试方案研究

在动力舱内复杂恶劣环境下,环境因素的影响给气压测试准确性以及不确定性带来了很多困扰。为了准确地研究动力舱出气口气压分布情况,需要采用分布式管式气压测试方法。但是,管道长度对气压参数测试会带来误差,这个问题必须首先得到解决。本文根据动力舱实际测试环境,设计了管长因素对气压误差影响分析测试系统,完成了不同管道长度对于气压参数测量结果的影响分析。运用差值一阶线性拟合方式,得到了差值拟合斜率与管道长度的对应关系。此研究解决了任意管道长度下对气压参数测试结果修正,提高管式气压参数测量精度,满足了动力舱出气口气压参数高精度测试需求。研究成果已应用实际工程问题,具有一定实用性。

COMBINED EFFECTS OF TEMPERATURE, IRRADIANCE AND SALINITY ON GROWTH OF DIATOM SKELETONEMA COSTATUM

factor experiment was used to study the combined effects of temperature, irradiance and salinity on the growth of an HAB species diatom Skeletonema costatum (Grev.) Cleve. The results showed that temperature (12, 19, 25, 32℃), irradiance ((0.02, 0.08, 0.3, 1.6)×10 16 quanta/(s·cm 2)) and salinity (10, 18, 25, 30, 35) significantly influenced the growth of this species. There were interactive effects between any two of and among all three physical factors on the growth. In the experiment, the most optimal growth condition for S. costatum was temparature of 25℃, salinity of 18-35 and irradiance of 1.6×10 16 quanta/(s·cm 2). The results indicated S. costatum could divide at higher rate and were more likely to bloom under high temperature and high illumination from spring to fall. It was able to distribute widely in ocean and estuary due to its adaptation to a wide range of salinities.

Teat Length and Lactation Period as A Predisposition Factor of Subclinical Mastitis in Dairy Cattle in Bandung, Indonesia

In order to improve the practical approach to clinical diagnosis of subclinical mastitis, 72 dairy cattle from KPSBU Lembang Bandung Regency was used in this research. The purpose of this research was to study the correlation between udder length and lactation period with the profile of subclinical mastitis. Lactation period data was collected from interviews with farmers. Subclinical mastitis testing by IPB-1 Mastitis Test reagent and udder length measured using measuring tape （cm）. Data was analyzed using Duncan test and logistic regression. The highest correlation of subclinical mastitis occurred to dairy cattle with average udder length of 7.5 cm and was in the third and forth lactation period. This result shows that udder length and lactation period of dairy cattle is a predisposing factor for subclinical mastitis. This finding is important to improve the milking management as well as a way to diagnose subclinical mastitis.

Relationships among hamstring muscle optimal length and hamstring flexibility and strength

Background:Hamstring muscle strain injury(hamstring injury) due to excessive muscle strain is one of the most common injuries in sports.The relationships among hamstring muscle optimal lengths and hamstring flexibility and strength were unknown,which limited our understanding of risk factors for hamstring injury.This study was aimed at examining the relationships among hamstring muscle optimal length and flexibility and strength.Methods:Hamstring flexibility and isokinetic strength data and three-dimensional kinematic data for hamstring isokinetic tests were collected for11 male and 10 female recreational athletes.The maximal hamstring muscle forces,optimal lengths,and muscle lengths in standing were determined for each participant.Results:Hamstring muscle optimal lengths were significantly correlated to hamstring flexibility score and gender,but not to hamstring strength.The greater the flexibility score,the longer the hamstring muscle optimal length.With the same flexibility score,females tend to have shorter hamstring optimal muscle lengths compared to males.Hamstring flexibility score and hamstring strength were not correlated.Hamstring muscle optimal lengths were longer than but not significantly correlated to corresponding hamstring muscle lengths in standing.Conclusion:Hamstring flexibility may affect hamstring muscle maximum strain in movements.With similar hamstring flexibility,hamstring muscle maximal strain in a given movement may be different between genders.Hamstring muscle lengths in standing should not be used as an approximation of their optimal lengths in calculation of hamstring muscle strain in musculoskeletal system modeling.

Sap Flow of Abies georgei var. smithii and Its Relationship with the Environment Factors in the Tibetan Subalpine Region, China

Abies georgei var. smithii is a dominant species playing an important role in protecting biodiversity and sustaining the forestry ecosystems in Southeastern Tibetan Plateau. Stem sap flows of five different diameters at the breast height(DBH) A. georgei var. smithii samples were monitored continuously with the thermal dissipation probe for the entire growing period in order to understand the water transportation mechanism and the effects of environmental factors on its transpiration and growth. Relative environment factors, temperature and humidity of air, photosynthetically active radiation, rainfall, and wind speed, soil moisture, etc. were measured by the automatic weather stations. Diurnal and seasonal variations in sap flow rate with the different stem diameters and their correlations with meteorological factors were analyzed. The diurnal change in sap flow velocity showed a single-peak curve at the daily time scale, whereas a lower sap flow velocity can be observed in the largest DBH sample tree at night. The maximum average velocity was observed in August, whereas the minimum velocity was observed in January, and a large amount of water evaporated in summer owing to the higher sap flow velocity. In addition, sap flow velocity was closely related to changes in the micrometeorological factors, with average sap flow velocity showing significant linear correlations with air temperature, photosynthetically active radiation, rainfall, and vapor pressure deficit of air and soil moisture. Therefore, some measures, improving the light and temperature conditions, should be taken for protecting A. georgei var. smithii population in the Tibetan Plateau.

Production of Interleukin 2 like Growth Factor from the Mitogen Activated Peripheral Blood Lymphocytes of Indian Major Carp, Labeo rohita

Optimum conditions for in vitro production of interleukin 2 （IL 2） like activity from the Peripheral blood lymphocytes （PBL） of an Indian major carp, Labeo rohita were studied. Culture supernatants were generated by culturing the PBL in RPMI-1640 media supplemented with Glutamine and 10% fetal bovine serum （FBS） and stimulating with two different mitogens： concanavalin A （Con A） and Phytohaemagglutinin （PHA） at different concentrations separately. Significantly （P 〈 0.01） higher proliferation response was obtained from the culture supematant stimulated with concanavalin A （Con A） at a concentration of 10 lag mLl. The effect of phorbol myristate acetate （PMA） was also studied by co-stimulating PBL with Con A and PHA separately and it was found to synergistically enhancing the stimulation index with Con A whereas the stimulation index remain unchanged with PHA. The Con A （10 μg mLl） stimulated PBL were also cultured at different cell density, incubation period and incubation temperature in order to optimize the in vitro L. rohita IL2 production. The IL2 like activity was studied by lymphocyte proliferation assay on 72 h Con A blasts using WST based assay technique. Significantly （P 〈 0.01） higher stimulation indices were obtained when the PBL were cultured at a cell density of 1 × 10^6 cells mL^-1 for 30-36 h at an incubation temperature of 30 ℃. The IL2 like activity was purified by DEAE-Sepharose anion exchange chromatography and recorded between 70-130 mM NaCI with peak activity at 110 Mm NaCI. The molecular weight of the factor responsible for IL2 like activity was found to be 15-17 KD.

Flowering responses to light and temperature

Light and temperature signals are the most important environmental cues regulating plant growth and development. Plants have evolved various strategies to prepare for, and adapt to environmental changes. Plants integrate environmental cues with endogenous signals to regulate various physiological processes, including flowering time. There are at least five distinct pathways controlling flowering in the model plant Arabidopsis thaliana: the photoperiod pathway, the vernalization/thermosensory pathway, the autonomous floral initiation, the gibberellins pathway, and the age pathway. The photoperiod and temperature/vernalization pathways mainly perceive external signals from the environment, while the autonomous and age pathways transmit endogenous cues within plants. In many plant species, floral transition is precisely controlled by light signals(photoperiod) and temperature to optimize seed production in specific environments. The molecular mechanisms by which light and temperature control flowering responses have been revealed using forward and reverse genetic approaches. Here we focus on the recent advances in research on flowering responses to light and temperature.