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261.
Developing prototypes of pressure sensitive mats and testing their practical application were the aims of this study. Two contact plate mats were designed and constructed: rubber-rubber (R) and metal-metal (M). A recipe for rubber mixes and the production technology were prepared. Two laboratory test stands for measuring the actuating force, response time, static pressure resistance, and the durability of the mats were constructed. Computer software was written to control the operation of those test stands. Methods of testing pressure sensitive mats were based on PrDIN 31 006 (Deutsches Institut fur Normung [DIN], 1990) and EN 1760–1 (Comite Europeen de Normalisation [CEN], 1997). Both prototypes of contact plate mats were tested under laboratory and industrial conditions.The test results proved that the design was correct, the setup requirements were fulfilled, and the mats were efficient and reliable in the industrial environment. 相似文献
262.
Jolanta Skowroń Lidia Zapór Katarzyna Miranowicz-Dzierżawska 《International journal of occupational safety and ergonomics》2013,19(1):107-116
The acute-toxic-class method (ATC) is an alternative to the classical LD50 test. Four substances were tested with an ATC testing procedure. The results were compared with LD50 data obtained from the literature. Great importance was attached to the observations of toxic signs following administration. The results of this study have shown that the ATC method allows allocation to toxicity classes in the same manner as on the basis of the classical LD50 tests. The ATC method uses fewer animals and yields the same information on toxic signs. Introducing the ATC method into the quality system allows estimating the acute oral toxicity of chemicals according to the Organisation for Economic Cooperation and Development (OECD; OECD, 1992, 1996). 相似文献
263.
Circadian Rhythm of Heart Rate,Urinary Cortisol Excretion,and Sleep in Civil Air Traffic Controllers
Krystyna Zużewicz Krzysztof Kwarecki Jim Waterhouse 《International journal of occupational safety and ergonomics》2013,19(3):383-392
The examination of Air Traffic Controllers (ATCs) from the Warsaw Airport (Poland) included 24-hr ECG monitoring. The participants were 10 civil ATCs, 9 males and 1 woman. The study was carried out on a group of 19 ATCs during their duty periods, 14 of them working 12-hr shifts and 5 performing 24-hr duties. The participants collected urine every 4 hrs, and Cortisol concentration was determined. Further, the survey included the quality and duration of sleep, and subjective fatigue in the 62 participants.In ATCs, shift work modifies natural rhythms of the circulatory system and decreases the ability for intensified mental work at night. In consequence ATCs experience frequent sleep disorders. 相似文献
264.
Magdalena Leszczyszyn-Pynka Małgorzata Kłys-Rachwalska Beata Sacharczuk Anna Boroń-Kaczmarska 《International journal of occupational safety and ergonomics》2013,19(4):425-429
We analyzed occupational exposure to potentially infectious body fluids among health care workers (HCWs). Nurses were the most common exposed category of HCWs. In 73.6% cases needle sticks had been the reason of exposure. Recapping a needle was the cause of exposure in 6.9% accidents. Among 189 registered HCWs, 66 (34.9%) performed invasive procedures without any personal protective equipment. Prophylaxis with antiretroviral drugs was necessary in 43 (22.8%) cases.As many as 60.3% of exposure incidents to potentially infectious material result from non-compliance with the relevant recommendations. Continuous education and training is critically needed to prevent occupational exposure to blood-borne infections among health care workers. 相似文献
265.
Aerosol concentration and particle size distributions in underground excavations of a hard coal mine
Krystian Skubacz Łukasz Wojtecki Paweł Urban 《International journal of occupational safety and ergonomics》2013,19(3):318-327
Deposition of aerosols in the respiratory system depends inter alia on their size and the respiratory tract deposition is appreciable for nanometer-sized particles. This article presents the results of measurements of size distributions of aerosols in the range of several nanometers up to about 20?μm in the underground mine excavations of an active hard coal mine. The study included practically all particles of a respirable fraction. The results showed that a high concentration of fine and ultrafine aerosols occurs in key underground workplaces especially during mining machine operations, although their contribution to total mass concentration is usually negligible. 相似文献
266.
The chromium(VI) biosorption onto guava seeds, as an alternative method for Cr6+ removal from aqueous solutions, was investigated. The parameters affecting kinetics and equilibrium of Cr6+ adsorption onto guava seeds were studied. An external mass-transfer diffusion coefficient k and intra-particle diffusion coefficient ki were determined to measure the rate-limiting step of adsorption. A single external mass-transfer diffusion model and intra-particle diffusion models were used. The effects of initial pH, sorbent mass, and initial Cr6+ concentrations on mass-transfer coefficients were investigated. The external mass-transfer coefficient has an average value of 7.2×10-3 cm s-1, while the intra-particle mass-transfer diffusion coefficient was 0.34 mg g-1 min-0.5. This indicates that external diffusion to the guava seeds surface and intra-particle diffusion are both involved in the sorption process. The isotherm equilibrium data were well fitted by the Langmuir and Freundlich models with an average correlation coefficient R2=0.98. The maximum removal of Cr6+ was obtained at pH 1 (about 100% for adsorbent dose of 15 g l-1 and 25 mg l-1 initial concentration of Cr6+). The results indicated that the guava seeds exhibit acceptable sorption capacity. 相似文献
267.
Highly activated carbon from the seed husk of Casuarina Casuarinas equisetifolia, a worldwide famous plant, have been prepared and tested for the removal of toxic Cr(VI) from its aqueous solution. The adsorbent was investigated for influences of initial chromium concentration (75, 100, 125, and 150 mg l-1), pH, contact time, and quantity of carbon on removal of Cr(VI) from aqueous solution at room temperature (25±2 °C). The adsorption kinetic of Cr(VI) was studied, and the rates of sorption were found to conform to pseudo-second-order kinetics with a good correlation (R2≥0.99). The Langmuir and Freundlich models fit the isotherm data well. Furthermore, the Gibbs free energy was obtained for each system and was found to be-5.29 kJ mol-1 for removal of Cr(IV). The negative value of Δ G° indicates the feasibility and spontaneous nature of adsorption. The results indicate that acidic pH (1.05) supported the adsorption of Cr(IV) on activated carbon. The maximum adsorption capacity of Cr(VI) on activated carbon was about 172.4 mg g-1 at pH 1.05. 相似文献
268.
Bolesław Zagalak 《Die Naturwissenschaften》1982,69(2):63-74
A critical review on corrinoid biochemistry and physiology is presented. This includes: chemical synthesis of biologically important organocorrinoids and the correlation between their structures and coenzymatic activity; forms, distribution and transport of physiologically active corrinoids; methylcobalamin- and adenosylcobalamin-dependent enzymatic reactions and their physiological functions; and steric course of the adenosylcobalamin-dependent enzymatic rearrangements. Special attention is paid to the mechanisms of adenosylcobalamin-dependent enzymatic reactions. 相似文献
269.
Maria Nowakowska Monika Sterzel Krzysztof Szczubiałka 《Journal of Polymers and the Environment》2006,14(1):59-64
Novel water-soluble polymeric photosensitizers based on a natural polymer, naphthalene-modified hydroxyethylcellulose (HENC),
were obtained and used for the photooxidation of cyanide. The reaction leads to the formation of cyanate. The process occurs
via photoinduced electron transfer from CN− to the naphthalene or naphthoquinone polymeric chromophores. The kinetics of the reaction depend on the degree of substitution
of HENC, its concentration, and pH of the solution. The polymers can be easily removed after reaction as prolonged irradiation
leads to their photodegradation. 相似文献
270.