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111.
A 2D physical model of the human head was used to investigate how the irregular skull base structure affects brain kinematics during sagittal plane head dynamics. The model consisted of a rigid skull vessel with interchangeable skull base structures. One version of the model used a skull base mimicking the irregular geometry of the human. A second version used a skull base structure approximating the anterior and middle fossae as a flat surface. Silicone gel simulated the brain and was separated from the vessel by a paraffin layer which provided a slip condition at the interface between the gel and vessel. The model was exposed to 7600 rad/s2 peak rotational acceleration with 6 ms pulse duration and 5° forced rotation. After 90° free rotation, the model was decelerated during 30 ms. Five repeated tests were conducted with each version. Rigid body displacement, shear strain and principal strains were determined from high-speed video recorded trajectories of grid markers located at different positions in the surrogate brain. The humanlike skull base reduced peak displacements of the inferior surfaces of the temporal and frontal lobes up to 87% and 48%, respectively. Up to 48% and 36% higher peak strains were obtained in the frontal and superior regions of the surrogate brain in the version containing the humanlike skull base. In contrast, the humanlike skull base decreased peak strain up to 28% in the central region of the surrogate brain. The results indicate that the irregular skull base offers natural protection of nerves and vessels passing through fissures and foramina in the cranial floor but also that it affects kinematics in different regions throughout the cerebrum. Implications of these results are discussed with respect to brain injury and modeling of head impact. 相似文献
112.
Şeker Mehmet Emin Erdoğan Ayşegül Korkmaz Seda Dicle Küplülü Özlem 《Environmental science and pollution research international》2022,29(24):36161-36169
Environmental Science and Pollution Research - In this study, pollens were collected from 25 different locations of Northern Turkey to investigate pollution monitoring. Surface chemistry of pollen... 相似文献
113.
Ebru Özgür Nilüfer Afsar Truus de Vrije Meral Yücel Ufuk Gündüz Pieternel A.M. Claassen Inci Eroglu 《Journal of Cleaner Production》2010
Biological hydrogen production by a sequential operation of dark and photofermentation is a promising route to produce hydrogen. The possibility of using renewable resources, like biomass and agro-industrial wastes, provides a dual effect of sustainability in biohydrogen production and simultaneous waste removal. In this study, photofermentative hydrogen production on effluents of thermophilic dark fermentations on glucose, potato steam peels (PSP) hydrolysate and molasses was investigated in indoor, batch operated bioreactors. An extreme thermophile Caldicellulosiruptor saccharolyticus was used in the dark fermentation step, and Rhodobacter capsulatus (DSM1710) was used in the photofermentation step. Addition of buffer, Fe and Mo to dark fermentor effluents (DFEs) improved the overall efficiency of hydrogen production. The initial acetate concentration in the DFE needed to be adjusted to 30–40 mM by dilution to increase the yield of hydrogen in batch light-supported fermentations. The thermophilic DFEs are suitable for photofermentative hydrogen production, provided that they are supplemented with buffer and nutrients. The overall hydrogen yield of the two-step fermentations was higher than the yield of single step dark fermentations. 相似文献
114.
115.
Mesut Ural Selami Arca Gürel Nedim Örnekçi Ferhat Demirol Songül Yüce Kazim Uysal 《毒物与环境化学》2013,95(1):49-55
Metal concentrations were determined in water, sediment, and freshwater fish samples (Squalus cephalus, Barbus esocinus, and Barbus xanthopterus) collected from Karakaya Dam Lake, Turkey, to estimate the risk of human consumption and pollution. Metal concentrations differed between the species (p?0.05) even as they were living in similar habitats. Metal analyses were performed by inductively coupled plasma optical emission spectroscopy (ICP-OES). Cd and Hg were not detected in water, sediment, and fish samples. Also, Mn, Ni, and Se were not determined in water. The accumulation order of the metals were found to be Fe?>?Zn?=?Cu in water and Fe?>?Zn?>?Mn?>?Ni?>?Cu in sediment. In general, the accumulation order of elements in the tissues all of the species sampled were found as Fe?>?Zn?>?Se?>?Mn?>?Cu?>?Ni?>?Cd in muscle, Zn?>?Fe?>?Mn?>?Se?>?Cu?>?Ni?>?Cd in gills, Fe?>?Zn?>?Se?>?Mn?>?Cu?>?Ni?>?Cd in liver and gonad, and Zn?>?Fe?>?Cu?>?Mn?>?Se?>?Ni?>?Cd in kidney. It was concluded that the fish from the dam lake are not heavily burdened with metals, but they should be controlled periodically to avoid excessive intake of trace metals by humans, and to monitoring the pollution of aquatic environment. 相似文献
116.
117.
Prenatal diagnosis of congenital atresia of the larynx is difficult but is possible by the findings of increased lung echogenicity and size coexisting with fetal ascites in ultrasonography. Sonographic findings may not always be typical. We report on a case of congenital laryngeal atresia diagnosed prenatally by the findings of fetal hydrops and hyperechogenic lungs. Our case presented with oligohydramnios. We also review syndromes that demonstrate laryngeal anomalies. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
118.
Efe Boran Ebru Özgür Job van der Burg Meral Yücel Ufuk Gündüz Inci Eroglu 《Journal of Cleaner Production》2010
The purpose of this study was to develop a pilot scale tubular photo bioreactor (80 L) for photo fermentative hydrogen production by photosynthetic purple-non-sulfur bacterium, Rhodobacter capsulatus, operating in outdoor conditions, using acetate as the carbon source. The reactor was operated continuously in fed-batch mode for 30 days throughout December 2008 in Ankara. It was placed in a greenhouse in order to keep the temperature above freezing levels. It was found that R. capsulatus had a rapid growth with a specific growth rate of 0.025 h?1 in the exponential phase. The growth was defined with modified logistic model for long term duration. The hydrogen production and feeding started in the late exponential phase. Evolved gas contained 99% hydrogen and 1% carbon dioxide by volume. The average molar productivity calculated during daylight hour was 0.31 mol H2/(m3 h) with regard to the total reactor volume and 0.112 mol H2/(m2·day) with regard to the total illuminated surface area. It was proven that even at low light intensities and low temperatures, the acetic acid which was fed to the system can be utilized for biosynthesis, growth and hydrogen production. The overall hydrogen yield was 0.6 mole H2 per mole of acetic acid fed. This study showed that photofermentation in a pilot scale tubular photo bioreactor can produce hydrogen, even in winter conditions. 相似文献
119.
Daniel Teixidor Thanongsak Thepsonthi Joaquim Ciurana Tugrul Özel 《Journal of Manufacturing Processes》2012,14(4):435-442
This paper reports an investigation into the effects of nanosecond laser processing parameters on the geometry of microchannels fabricated from polymethylmethacrylate (PMMA). The Nd:YAG solid-state pulsed laser has a wavelength of 1064 nm and a measured maximum power of 4.15 W. The laser processing parameters are varied in a scanning speed range of 400–800 pulses/mm, a pulse frequency range of 5–11 Hz, a Q-switch delay time range of 170–180 μs. Main effects plots and microchannel images are utilized to identify the effects of the process parameters for improving material removal rate and surface quality simultaneously for laser micromachining of microchannels in PMMA polymer. It is observed that channel width and depth decreased linearly with increasing Q-switch delay time (hence average power) and increased non-linearly with higher scanning rates and not much affected by the increase in pulse frequency. 相似文献
120.
In this study, two pilot-scale aerobic landfill reactors with (A1) and without (A2) leachate recirculation are used to obtain
detailed information on the quantity and quality of leachate in aerobic landfills. The observed parameters of leachate quality
are pH, chloride (Cl−), chemical oxygen demand (COD), biological oxygen demand (BOD), total Kjeldahl nitrogen (TKN), ammonia nitrogen (NH3-N), and nitrate (NO3–-N). pH values of the leachate increased to 7 after 50 days in reactor A1 and after 70 days in reactor A2. Cl− concentrations increased rapidly to 6100 (A1) and 6900 (A2) mg/L after 80 days, from initial values of 3000 and 2800 mg/L,
respectively. COD and BOD values decreased rapidly in the A1 landfill reactor, indicating the rapid oxidation of organic matter.
The BOD/COD ratio indicates that leachate recirculation slightly increases the degradation of solid waste in aerobic landfills.
NH3-N concentrations decreased as a result of the nitrification process. Denitrification occurred in parts of the reactors as
a result of intermittent aeration; this process causes a decrease in NO3− concentrations. There is a marked difference between the A1 and A2 reactors in terms of leachate quantity. Recirculated leachate
made up 53.3% of the leachate generated from the A1 reactor during the experiment, while leachate quantity decreased by 47.3%
with recirculation when compared with the aerobic dry landfill reactor. 相似文献