Measurement and estimation of species distribution in a direct methanol fuel cell

Determination of methanol concentration in a direct methanol fuel cell is crucial for design improvement and performance enhancement. Methanol and water concentrations in a direct methanol fuel cell are experimentally and numerically investigated. In the experimental program, a single cell direct methanol fuel cell is developed and an experimental setup is devised to measure methanol and water concentrations and performance of the cell depending on operating conditions. In theoretical program a mathematical model which includes fluid flow, species distribution, electric field and electrochemistry is adapted and numerically solved. The results showed that the performance of a Direct Methanol Fuel Cell (DMFC) is mainly influenced by operating temperature. A large drop in methanol concentration methanol is measured at the inlet section of cell. The mathematical model is found to satisfactorily capture main physics involved in a DMFC.     

Endurance time of grip-force as a function of grip-span, posture and anthropometric variables

The time to volitional exhaustion (endurance time) for sustained contractions is considered as a valid parameter to quantify fatigue and to determine the required rest pauses between two successive contractions. In this study, the effects of grip-span, shoulder posture and anthropometric characteristics on endurance time of grip-force during sustained 30% of maximal voluntary grip-force were investigated. Both subjective and objective measures of fatigue were used in determining the endurance times. Twelve male subjects performed sustained isometric handgrip contractions using a handgrip dynamometer at the combinations of three different grip span settings and two shoulder postures. The investigated three grip spans were the optimal, 2 cm narrower than the optimal, and 2 cm wider than the optimal. The investigated two shoulder postures were neutral and 25° flexion. The outcome measures were: endurance time, surface electromyography of related forearm muscles, heart rate, blood pressure, and ratings of perceived discomfort/pain. The results indicate that the endurance time decreases significantly as the grip span deviates from the optimal in both directions. On the other hand, the considered shoulder postures did not have a significant effect on the endurance time. Further analysis indicated a significant negative correlation between endurance time and rest pause and a marginal positive correlation between maximum voluntary grip-force and rest pause. Body mass index, and volume of forearm and hand had also significant negative correlation with endurance time. The comparisons are made with a number of existing endurance models and the impact of findings are discussed.

Relevance to industry

In accurate establishment of the time standards, muscular fatigue allowances need to be taken into account. The endurance time for sustained isometric contractions is correlated with the required rest allowances (pauses) for intermittent static contractions; and therefore, required muscular fatigue allowances can be estimated from the endurance times.     

光波导化学传感器的数据采集和分析软件的开发

在光波导化学传感器研究中,辐照计检测的光强度由记录器(打印机)显示。对观察、记录、分析和保存检测的数据极不方便。因此提高和改进光波导检测系统的性能,用VB6.0编程语言开发数据采集和分析软件。通过数据采集卡将辐照计连接计算机并用该软件记录、处理、分析和保存检测数据,一整套实时图形化显示过程。本论文详细介绍检测系统的硬件、软件结构和性能,它不需要任何应用软件支持,可以在Windows中直接运行,界面友好、操作方便、运行稳定性好。计算机采集和处理检测数据使新系统在灵敏度、可靠性、响应速度和检测数据的精密度等方面超过了原来系统的性能,并为检测、研究该类传感器在智能化方面提供指导作用。     

Reducing energy consumption of parallel sparse matrix applications through integrated link/CPU voltage scaling

Reducing power consumption is quickly becoming a first-class optimization metric for many high-performance parallel computing platforms. One of the techniques employed by many prior proposals along this direction is voltage scaling and past research used it on different components such as networks, CPUs, and memories. In contrast to most of the existent efforts on voltage scaling that target a single component (CPU, network or memory components), this paper proposes and experimentally evaluates a voltage/frequency scaling algorithm that considers CPU and communication links in a mesh network at the same time. More specifically, it scales voltages/frequencies of CPUs in the nodes and the communication links among them in a coordinated fashion (instead of one after another) such that energy savings are maximized without impacting execution time. Our experiments with several tree-based sparse matrix computations reveal that the proposed integrated voltage scaling approach is very effective in practice and brings 13% and 17% energy savings over the pure CPU and pure communication link voltage scaling schemes, respectively. The results also show that our savings are consistent with the different network sizes and different sets of voltage/frequency levels.

Chitotriosidase as a novel biomarker of early atherosclerosis in hemodialysis patients

Introduction: Increasing evidence suggests that inflammation and increased macrophage activity have a central role in pathogenesis of atherosclerosis. It is shown that chitotriosidase (CHIT‐1) is a marker of macrophage activity in atherosclerotic plaque, and is found associated with severity of atherosclerotic lesion. There is no data about CHIT‐1 activity of hemodialysis patients in the literature. Thus, we hypothesized that in hemodialysis patients, CHIT‐1 levels might be a novel biomarker in early atherosclerosis. Methods: Forty‐five hemodialysis patients were included in the study (age: 61.93 ± 13.34). Intima media thickness (IMT) was evaluated with high‐resolution B‐mode ultrasonography. Biomarker levels were measured in serum of patients. Findings: We found positive correlation among IMT, age (R: 0.426, P: 0.004) and, CHIT‐1 value (R: 0.462, P: 0.001) in spearman correlation analysis. When age, CRP, creatinine, P, Alb, CHIT‐1 were chosen as measures that can effect IMT in multiple regression model, IMT level was related with CHIT‐1 (Beta: 0,396, P: 0.012) and age (Beta: 0,313 P: 0,048) independently. Discussion: In conclusion, this is the first report showing that serum CHIT‐1 level was related independently with carotid IMT in hemodialysis patients. This biomarker might have an unknown role in the development of atherosclerosis during uremia.     

Vascular proteomics and the discovery process of clinical biomarkers: The case of TWEAK

In the last years, big efforts are devoted to the search of novel biomarkers. Proteomic approaches in healthy and pathological samples may help us to discern differential protein expression patterns. These identified proteins include potential culprits in pathological pathways and/or clinical biomarkers to identify individuals at risk. However, extensively validation must be carried out before their implementation into the clinical practice. Biomarkers need to discriminate between health and disease, detect preclinical disease stages, have impact on survival prediction, and add predictive value beyond traditional risk factors and global risk algorithms. Now, we summarize the data of soluble tumor necrosis factor-like weak inducer of apoptosis (sTWEAK), a new cardiovascular biomarker identified by proteomic analysis. Decreased sTWEAK concentrations have been shown in patients with carotid atherosclerosis, coronary artery disease, congestive heart failure, peripheral artery disease, or chronic kidney disease (CKD). sTWEAK predicted adverse outcomes in patients with heart failure, myocardial infarction, and CKD. Finally, different drug regimens were able to modify sTWEAK plasma levels in patients with CKD. Although sTWEAK seems so far to fulfill the requisites in the development of a new biomarker, more large-scale studies are warranted to consolidate its usefulness.     

Impacts of impregnation chemicals on combustion properties of the laminated wood materials produced combination of beech and poplar veneers

The aim of this study was to investigate the effects of impregnation with boron compounds Borax (B_X), Boric acid (B_A), B_X + B_A, Imersol-Aqua (I_AQUA) and Timbercare-Aqua (T_AQUA) on combustion properties of the laminated wood materials produced combination of Oriental beech and poplar veneers bonded with Desmodur-VTKA (D_V) and Poly(vinyl acetate) (P_VAc) adhesives. The test samples, prepared from beech (Fagus orientalis Lipsky) and poplar (Populus nigra Lipsky) woods, were impregnated boron compounds by vacuum, I_AQUA by dipping and T_AQUA by brushing methods according to ASTM D 1413-76-99 and directions of the manufacturer. The laminated wood materials were prepared in the form of five layers, 4 mm thickness from the impregnated beech and poplar veneers according to TS EN 386. Combustion properties of samples after laminated and impregnated process were determined according to ASTM E 160-50. Considering the interaction of combustion type and impregnation materials, combustion temperature was found the highest in flame source combustion (F_SC) + T_AQUA (528.150 °C) but the lowest in without flame source combustion (WF_SC) + B_A (391.333 °C). Consequently, boron compounds and I_AQUA showed a decreasing impact on combustion properties of the laminated wood materials, produced combination of beech and poplar veneers, bonded with D_V. In consequence, impregnation with boron compounds and Imersol-Aqua of the laminated wood materials, bonded with Desmodur-VTKA, provides security for the usage of having high risk of fire.     

新疆红果桑果实总生物碱的提取工艺的研究

采用分光光度法,以盐酸小檗碱为标准品测定新疆红果桑中的总生物碱含量。在提取过程中通过单因素试验分析乙醇体积分数、料液比、提取时间及提取温度4 个主要因素对提取率的影响。在单因素试验的基础上通过正交设计法进行试验,优化红果桑总生物碱提取工艺条件。结果表明：红果桑总生物碱的最佳提取工艺条件为乙醇体积分数90%、料液比1:15、提取温度70℃、提取时间6h。根据最佳提取工艺条件测得的红果桑的总生物碱提取率为2.5%。该实验结果可靠,方法简便,最佳条件适合批量生产中该药材的提取。     

Anaerobic co-digestion of chicken and cattle manures: Free ammonia inhibition

In this study, 4 different anaerobic digesters were set by keeping the chicken manure ratios as 0%, 30%, 70%, and 100% by completing the remaining portions with cattle manures. According to the results, the highest methane production potentials were 144 ± 7, 201 ± 12, 217 ± 3, 256 ± 5 L/kg VS_added, respectively. After reaching the highest total nitrogen concentrations in semi continuously operated reactors, methane level has dropped due to free ammonia (as high as 652 mg NH₃-N/L) inhibition stimulated by high pH in all reactors. Recovery of the methane production following free ammonia inhibition was greatly succeeded although deficiency in essential trace elements such as Cd and Ni. Nevertheless, it was shown that cattle manure alone can be a good co-substrate for the chicken manure.     

Fractionation and characterization of edible sheep tail fat

Edible sheep tail fat was effectively fractionated by an acetone crystallization. Each of the fractions and filtrates were analyzed for melting point, refractive index, iodine value, fatty acid composition, and characterized by differential scanning calorimetry. Fatty acid analysis indicated that as the fractionation temperature decreased, the concentration of unsaturated fatty acids in the fractions increased. The liquid fraction had a differential scanning calorimetry melting curve similar to commercial salad oil and the curve of one of the filtrates resembled that of cocoa butter.