An automated differential thermal and potentiometric titration apparatus for binding studies

A differential pH-termal titration apparatus is described which can detect pH differences with a sensitivity of ±0.0001 pH units and a thermal sensitivity of ±0.00002°C at a time constant of 0.1 s. With a reaction which yields 1 kcal mol⁻¹, the current system can detect concentrations as low as 4×10⁻⁶ M or, in a 2 ml volume, a total amount of 40 nmol. With a time constant of 0.1 s, the sensitivity is 20±4 μ°C. The experimental protocol is specified by a microprocessor and three modes of operation are possible: titration at constant rate of reagent addition, titration at variable rates of addition so that the contents of both cells are at either constant pH or at a constant temperature and variable rate when a rate of change is specified. Experimental data are collected in files, corrected for heat loss, initial baseline drift, and changes in volume. The final corrected from the standardized run of 0.01338 M HCl in 0.2 M KCl at 25°C calibrate the pH scale yielded the calorimetric conversion constants and pK_w which are calculated and stored for subsequent corrections for the titration of an unknown acid or the measurement of bindin constants and heats.     

The influence of nest site selection on the population dynamics of Africanized honey bees in an urban landscape

Urban landscapes provide habitat for many species, including domesticated and feral honey bees, Apis mellifera L. (Hymenoptera: Apidae). With recent losses of managed honey bee colonies, there is increasing interest in feral honey bee colonies and their potential contribution to pollination services in agricultural, natural, and urban settings. However, in some regions the feral honey bee population consists primarily of Africanized honey bees. Africanized honey bees (AHB) are hybrids between European honey bees and the African honey bee, Apis mellifera scutellataLepeletier, and have generated economic, ecological, and human health concerns because of their aggressive behavior. In this study, we used two long‐term datasets (7–10 years) detailing the spatial and temporal distribution of AHB colonies in Tucson, AZ, USA, where feral colonies occupy a variety of cavities including water meter boxes. A stage‐structured matrix model was used to elucidate the implications of nest site selection and the effects of colony terminations on the structure and dynamics of the AHB population. Our results suggest that Tucson's AHB population is driven by a relatively small number of ‘source’ colonies that escape termination (ca. 0.165 colonies per km² or 125 colonies in total), although immigrating swarms and absconding colonies from the surrounding area may have also contributed to the stability of the Tucson AHB population. Furthermore, the structure of the population has likely been impacted by the number and spatial distribution of water meter boxes across the city. The study provides an example of how urban wildlife populations are driven by interactions among landscape structure, human management, and behavioral traits conferred by an invasive genotype.     

Genetic variation of salt-stressed durum wheat (Triticum turgidum subsp. durum Desf.) genotypes under field conditions and gynogenetic capacity

Agriculture has new challenges against the climate change: the preservation of genetic resources and the rapid creation of new varieties better adapted to abiotic stress, specially salinity. In this context, the agronomic performance of 25 durum wheat (Triticum turgidum subsp. durum Desf.) genotypes (nineteen landraces and six improved varieties), cultivated in two semi-arid regions in the center area of Tunisia, were assessed. These sites (Echbika, 2.2?g?l^?1; Barrouta, 4.2?g?l^?1) differ by their degree of salinity of the water irrigation. The results showed that most of the agronomic traits (e.g. spike per meter square, thousand kernels weight and grain yield) were reduced by salinity. Durum wheat landraces, Mahmoudi and Hmira, and improved varieties, Maali and Om Rabia showed the widest adaptability to different quality of irrigation water. Genotypes including Jneh Kotifa and Arbi were estimated as stable genotypes under adverse conditions. Thereafter, salt-tolerant (Hmira and Jneh Khotifa) and the most cultivated high-yielding (Karim, Razzak and Khiar) genotypes were tested for their gynogenetic ability to obtain haploids and doubled haploid lines. Genotypes with good induction capacity had not necessarily a good capacity of regeneration of haploid plantlets. In our conditions, Hmira and Khiar exhibited the best gynogenetic ability (3.1% and 2.9% of haploid plantlets, respectively).     

应用高精度pH计测定植物的光合速率和呼吸速率

为方便、准确地测定植物的光合速率和呼吸速率,将高精度pH计和高灵敏复合电极引入测定系统.结合样品的测定,阐明了pH计法的测定原理、气路连接和复合电极的标定,并指出了测定过程中应注意的事项.     

Determining Noise in an Aggregates Plant Using Functional Statistics

A key issue to be taken into account in any mining operation or premises is workers’ health and safety. Noise has negative repercussions on workers’ health, which is why regular inspections of noise levels are necessary to ensure that noise is less than legally permitted limits. In our study we statistically analyzed functional data with a view to determining noise levels in an aggregates plant. Data were captured by a sound level meter that indicated equivalent sound pressure levels and peaks and the octave bands for a specific range of frequencies. Unlike the methods habitually used to construct noise maps (which only permit one of these parameters to be determined for each point), the methods applied in our research enable the noise level to be calculated at each point for the entire spectrum of frequencies picked up by a sound level meter. For each point we obtain, rather than a single value, a noise curve reflecting the entire range of frequencies detected by the sound level meter. This enables us to better understand the effects of noise and to determine its origin.     

上肢精准电磁功率计（臂力计）用于心肺代谢等整体功能评估的临床观察研究*

目的: 受试者分别用上肢（臂力计）和下肢精准电磁功率计（自行车）进行症状限制性极限心肺运动试验（CPET）,分析探讨上肢CPET的临床价值。方法: 15例受试者（正常人6例和慢病患者9例）签署知情同意书后在不同的2 d里分别完成上肢和下肢精准电磁功率计CPET,分析CPET数据、计算相关核心指标,探究上肢和下肢CPET的异同及其相关性。结果: ①全体15例受试者男8女7,其中6例正常人和9例慢病患者亚组相比仅年龄（（33.2±12.7）比（53.6±8.5）岁）和无诊断疾病有显著差异（P<0.05）。②全体受试者上肢CPET峰值心率（（131.0±19.0）比（153.0±22.0） bpm,P<0.05）和血压均低于下肢CPET,但血压差异无统计学意义（P>0.05）;上肢CPET的峰值潮气量（（1.3±0.4）比（1.8±0.4） L）和分钟通气量（（51.4±21.1）比（67.9±22.1） L/min）均显著低于下肢（P均<0.05）,而峰值呼吸频率无显著差异;采用上肢CPET时,运动时间（（6.4±0.6）比（8.5±1.2） min）要短于下肢CPET;峰值负荷功率（（73.2±19.6）比（158.5±40.3）W/min）、峰值摄氧量（（1.1±0.4）比（1.7±0.4）L/min）、无氧阈（（0.6±0.2）比（0.9±0.2） L/min）、峰值氧脉搏（（8.6±2.3）比（10.9±2.6） ml/beat）、摄氧通气效率峰值平台（34.7±4.3比39.8±5.3）均较低,而二氧化碳排出通气效率最小值（32.6±3.8比28.7±4.9）及斜率（33.9±4.3比28.3±6.2）高于下肢CPET（P均<0.05）。正常人和慢病两亚组各自的比较结果与整体比较结果无显著差异。③上肢CPET的运动时间,峰值心率,峰值呼吸频率、潮气量、分钟通气量,峰值负荷功率实测值及百分预计值,峰值摄氧量实测值、公斤体重值和百分预计值,无氧阈实测值、公斤体重值,峰值氧脉搏的实测值,摄氧通气效率峰值平台、二氧化碳排出通气效率最小值和斜率的实测值及百分预计值与下肢CPET的结果相关性较好,其余指标无显著相关性。结论: 作为下肢CPET的补充,上肢CPET用于整体功能状态评估具有极高的可行性和更高的安全性,对于指导安全有效个体化精准运动整体方案的实施提供了重要补充,值得进一步深入探究。     

饲料原料中有毒有害物质的综合毒性测定法初探

目的建立发光细菌综合毒性测定法,对实验动物饲料原料中有毒有害物质进行初筛.方法用发光细菌作指示生物,测定金属离子Pb2+,Zn2+,Cr+,Hg2+和毒性物质苯酚,灭害灵;以Hg2+为毒性对照物,测定10种饲料原料和3种人用食品.结果发光菌对有毒有害物质和金属离子敏感.在所测定的范围内,其发光强度随浓度增加而减弱,即相对抑光率增强,呈负线性相关,其相关系数在0.92以上;以Hg2+为毒性对照物,对10种饲料原料和3种人用食品进行测定,其中脱水蔬菜相对抑光率最大,为39.74%,相当于1.85×10-5%Hg2+的表征毒性,提示该样品可能受到农药和化肥等较严重的污染.结论发光细菌综合毒性测定法,可用于饲料原料中有毒有害物质的初筛,是一种快速、经济、有效的方法.     

Experimental study on convective heat transfer coefficient of the human body

1. 1. The convective heat transfer coefficient of the human body is essential to predict convective heat loss from the body.

2. 2. The object of this paper is to calculate the convective heat transfer coefficient of the human body using heat flow meters and to estimate the thermally equivalent sphere and cylinder to the human body.

3. 3. The experimental formulae of the convective heat transfer coefficient for the whole body were obtained by regression analysis for natural, forced and mixed convection.

4. 4. Diameters of the thermally equivalent sphere and cylinder of the human body were calculated as 12.9 and 12.2 cm, respectively.

Spatial and temporal RF electromagnetic field exposure of children and adults in indoor micro environments in Belgium and Greece

Personal radio frequency electromagnetic field (RF-EMF) exposure, or exposimetry, is gaining importance in the bioelectromagnetics community but only limited data on personal exposure is available in indoor areas, namely schools, crèches, homes, and offices. Most studies are focused on adult exposure, whereas indoor microenvironments, where children are exposed, are usually not considered. A method to assess spatial and temporal indoor exposure of children and adults is proposed without involving the subjects themselves. Moreover, maximal possible daily exposure is estimated by combining instantaneous spatial and temporal exposure. In Belgium and Greece, the exposure is measured at 153 positions spread over 55 indoor microenvironments with spectral equipment. In addition, personal exposimeters (measuring EMFs of people during their daily activities) captured the temporal exposure variations during several days up to one week at 98 positions. The data were analyzed using the robust regression on order statistics (ROS) method to account for data below the detection limit. All instantaneous and maximal exposures satisfied international exposure limits and were of the same order of magnitude in Greece and Belgium. Mobile telecommunications and radio broadcasting (FM) were most present. In Belgium, digital cordless phone (DECT) exposure was present for at least 75% in the indoor microenvironments except for schools. Temporal variations of the exposure were mainly due to variations of mobile telecommunication signals. The exposure was higher during daytime than at night due to the increased voice and data traffic on the networks. Total exposure varied the most in Belgian crèches (39.3%) and Greek homes (58.2%).