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排序方式: 共有71条查询结果,搜索用时 15 毫秒
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Jonas Sidaravicius Ringaudas Rinkūnas Justinas Jurksus Tadeus Lozovski Isto Heiskanen Kaj Backfolk 《应用聚合物科学杂志》2014,131(22)
The number of polymers successfully electrospun is increasing, and methods are needed predict the electrospinnability of polymers. With such methods, researchers should consider the polymer solution parameters and perform measurements in conditions that mimic the electrospinning process. A novel test method based on the electromechanical simulation of the fiber formation was developed. We formed fibers by mechanically dragging a conductive ball from the solution at an applied voltage and measuring the electrical current. The changes in the time of the electrical current (the ball current) reflect the fiber‐formation process, which depended on certain polymer solution properties (e.g., viscosity, surface tension, liquid flow) and on the influence of charges on the fiber surface. The data obtained with the proposed method was compared with experimental data from electrospinning trials with the spinneret and bubble electrospinning. The results demonstrate that the ball‐current method made it possible to predict the polymer solution behavior in the electrospinning process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41091. 相似文献
3.
Distribution of bacteria in a domestic hot water system in a Danish apartment building 总被引:1,自引:0,他引:1
Bacterial growth in hot water systems seems to cause problems such as bad odor of the water, skin allergies and increased heat transfer resistance in heating coils. In order to establish a basis for long-term suppression of bacterial growth, we studied the distribution of bacteria in a Danish domestic hot water system. Heterotrophic plate counts (HPC) were measured in both water and biofilm samples from various sampling sites in the system. In hot water samples, where the temperature was 55-60 degrees C, the HPC were 10(3)-10(4)CFU/mL at incubation temperatures of 25 degrees C or 37 degrees C and 10(5)CFU/mL at 55 degrees C or 65 degrees C. In the cold water (10 degrees C) supplying the hot water system, the HPC at 25 degrees C or 37 degrees C was lower than in the hot water, and no bacteria were found after incubation at 55 degrees C or 65 degrees C. HPC constituted from 38% to 84% of the AODC results in hot water but only 2% in cold water, which showed a high ratio of culturable bacteria in hot water. Biofilm samples from the hot water tank and the inner surface of the pipes in the cold and hot water distribution system were collected by specially designed sampling devices, which were exposed in the system for 42 days. The quasi-steady-state number of bacteria in the biofilm, measured as the geometric mean of the HPC obtained between 21 and 42 days, was five-fold higher in the hot water pipe (13x10(5)CFU/cm(2) at 55 degrees C) than in the cold water pipe (2.8x10(5)CFU/cm(2) at 25 degrees C). There was no significant difference between the number of bacteria in the biofilm samples from the top, middle and bottom of the hot water tank, and the number of bacteria in the biofilm counted at 55 degrees C ranged from 0.6x10(4) to 1.7x10(4)CFU/cm(2). The surfaces of the sacrificial aluminum anodes and the heating coils in the hot water tank also contained high bacterial numbers. The measured number of bacteria in water and biofilm samples was related to the dimensions of the hot water system, and calculations showed that the majority of bacteria (72%) were located in the biofilm especially in the distribution system, which accounts for the greatest surface area. Free-living bacteria accounted for 26% and only a minor part of the bacteria were in the sludge in the hot water tank (2%). 相似文献
4.
Moriguchi CS Carnaz L Veiersted KB Hanvold TN Hæg LB Hansson GÅ Cote Gil Coury HJ 《Applied ergonomics》2013,44(1):86-92
The aim of this study is to record, objectively describe and compare working postures of Brazilian and Norwegian construction electricians. Postures of the upper arms, head, and neck during work and breaks were quantified by means of inclinometry for a representative sample of 12 Brazilian and 12 Norwegian electricians in the construction industry during a full work-shift. Despite that differences were found between specific work-related factors, Brazilian and Norwegian workers revealed a high and very similar level and pattern of postures for all evaluated body regions, suggesting that results could be extrapolated to other electricians. Upper arm elevation was high and similar for both groups and head flexion and extension was pronounced compared to other occupations. Thus, extreme postures were identified for construction electricians in both countries, with similar exposure pattern also for defined tasks (planning, support and wiredraw), suggesting that this job is risky regardless organizational differences. 相似文献
5.
Kaj Ovesen 《Building Research & Information》2013,41(5):319-320
Kaj Ovesen of the Danish Building Institute and former co‐ordinator of the CIB Commission discusses harmonization of the European water and drainage building regulations. 相似文献
6.
Liyun Yang Ke Lu Mikael Forsman Kaj Lindecrantz Fernando Seoane Örjan Ekblom 《Ergonomics》2019,62(5):694-705
Work metabolism (WM) can be accurately estimated by oxygen consumption (VO2), which is commonly assessed by heart rate (HR) in field studies. However, the VO2–HR relationship is influenced by individual capacity and activity characteristics. The purpose of this study was to evaluate three models for estimating WM compared with indirect calorimetry, during simulated work activities. The techniques were: the HR-Flex model; HR branched model, combining HR with hip-worn accelerometers (ACC); and HR?+?arm-leg ACC model, combining HR with wrist- and thigh-worn ACC. Twelve participants performed five simulated work activities and three submaximal tests. The HR?+?arm-leg ACC model had the overall best performance with limits of agreement (LoA) of ?3.94 and 2.00?mL/min/kg, while the HR-Flex model had ?5.01 and 5.36?mL/min/kg and the branched model, ?6.71 and 1.52?mL/min/kg. In conclusion, the HR?+?arm-leg ACC model should, when feasible, be preferred in wearable systems for WM estimation.
Practitioner Summary: Work with high energy demand can impair employees’ health and life quality. Three models were evaluated for estimating work metabolism during simulated tasks. The model combining heart rate, wrist- and thigh-worn accelerometers showed the best accuracy. This is, when feasible, suggested for wearable systems to assess work metabolism. 相似文献
7.
Mass Spectrometric Analysis of Cerebrospinal Fluid Ubiquitin in Alzheimer's Disease and Parkinsonian Disorders
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Simon Sjödin Oskar Hansson Annika Öhrfelt Gunnar Brinkmalm Henrik Zetterberg Ann Brinkmalm Kaj Blennow 《Proteomics. Clinical applications》2017,11(11-12)
1 Purpose
Dysfunctional proteostasis, with decreased protein degradation and an accumulation of ubiquitin into aggregated protein inclusions, is a feature of neurodegenerative diseases. Identifying new potential biomarkers in cerebrospinal fluid (CSF) reflecting this process could contribute important information on pathophysiology.2 Experimental design
A developed method combining SPE and PRM‐MS is employed to monitor the concentration of ubiquitin in CSF from subjects with Alzheimer's disease (AD), Parkinson's disease (PD), and progressive supranuclear palsy (PSP). Four independent cross‐sectional studies are conducted, studies 1–4, including controls (n = 86) and participants with AD (n = 60), PD (n = 15), and PSP (n = 11).3 Results
The method shows a repeatability and intermediate precision not exceeding 6.1 and 7.9%, respectively. The determined LOD is 0.1 nm and the LOQ range between 0.625 and 80 nm . The CSF ubiquitin concentration is 1.2–1.5‐fold higher in AD patients compared with controls in the three independent AD‐control studies (Study 1, p < 0.001; Study 2, p < 0.001; and Study 3, p = 0.003). In the fourth study, there is no difference in PD or PSP, compared to controls.4 Conclusion and clinical relevance
CSF ubiquitin may reflect dysfunctional proteostasis in AD. The described method can be used for further exploration of ubiquitin as a potential biomarker in neurodegenerative diseases. 相似文献8.
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Jesper Thaysen Kaj B. Jakobsen 《AEUE-International Journal of Electronics and Communications》2007,61(8):540-545
Mutual coupling between two identical planar inverted-F antennas (PIFA) located on an infinite ground plane is studied numerically. Several arrangements of side-by-side, collinear, parallel-in-echelon, and orthogonal PIFA antennas with element spacing varying from to are investigated at the design frequency of 1.9 GHz, and in the bandwidth between 1.8 and 2.0 GHz. It is found that choosing configurations that maximizes the separation between the open-end of the PIFAs reduces the mutual coupling. 相似文献
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