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41.
42.
In this study, visible light‐driven heterogeneous photocatalysts for hydrogen production are comparatively assessed based on technical, environmental, and cost criteria. The photocatalysis systems are compared with respect to their (i) rate of hydrogen generation per gram; (ii) rate of hydrogen generation per m2 of the specific surface area; and (iii) the band gap energy. The photocatalysis systems are also compared and discussed in terms of flammability, reactivity, and their impact on living systems' health. Furthermore, the costs of the required components of the photocatalysis systems are ranked. In addition to individual photocatalyst comparison, seven photocatalyst groups are ranked and compared. The results show that TiO2‐C‐362 and Ag0.03Mn0.40Cd0.60S show the highest in terms of µmol/h‐gcat and µmol/h‐m2cat, respectively, and TiO2‐C‐362 has the highest overall rankings. The Zn/In/S‐based photocatalyst groups show the highest hydrogen production rate in terms of µmol/h‐gcat and µmol/h‐m2cat. Overall, Cd/S/Zn has the highest rankings when cost and health and environmental impact criteria are taken into account. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
43.
The purpose of this study was to evaluate the knowledge, attitudes and practices among food service staff with regards to food hygiene in hospitals in Edirne, Turkey, and to provide baseline data for implementing HACCP in hospital food services by carrying out a questionnaire by a face-to-face interview. The current study shows that food service staff in Edirne hospitals have insufficient knowledge regarding the basics of food hygiene. And also revealed a discrepancy between attitudes and practices towards food hygiene. There is an immediate need for continuous training among food handlers regarding safe food handling practices. 相似文献
44.
Ayse Altin Burcin Akgun Ozlem Buyukgumus Zeynep Sarayli Bilgici Sesil Agopcan Didar Asik Havva Yagci Acar Duygu Avci 《Reactive and Functional Polymers》2013,73(9):1319-1326
An urea methacrylate (1) and two phosphonated methacrylates (2–3) were synthesized from 2-isocyanatoethyl methacrylate (IEM) and benzyl amine (1), diethyl aminomethylphosphonate (2) and diethyl amino(phenyl)methylphosphonate (3). Their photopolymerization rates are notably higher than commercial monomers, despite the presence of only one double bond. Their polymerization rates follow the order 1 ~ 2 > 3 ~ triethylene glycol dimethacrylate (TEGDMA) > 2-hydroxyethyl methacrylate (HEMA). A tendency toward high crosslinking density during thermal bulk polymerizations, low oxygen sensitivity and high conversions with benzophenone during photopolymerization indicated the importance of hydrogen abstraction/chain transfer reactions. It was found that the addition of the monomers to HEMA significantly increased its polymerization rate, proving their utility as replacements for TEGDMA as reactive diluents for 2,2-bis[4-(2-hydroxy-3-methacryloyloxy propyloxy) phenyl] propane (Bis-GMA). Copolymer systems containing 2 and 3 showed improved Tg values compared to Bis-GMA/TEGDMA systems. 相似文献
45.
46.
Suphi S. Oncel Esra Imamoglu Emre Gunerken Fazilet Vardar Sukan 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(3):414-420
BACKGROUND: Recent studies indicate that microalgal cultivation using organic carbon sources has the potential to provide high yields. Haematococcus pluvialis and Chlorella zofingiensis, two important carotenoid producers, were selected for co‐culture cultivations to utilize the unique advantages of both organisms. A co‐culture production process was investigated in terms of the effects of organic carbon source, co‐cultivation method, and light intensity on carotenoid production. RESULTS: The addition of 5 g L?1 glucose resulted in a growth rate of 0.60 day?1 for H. pluvialis and 0.59 day?1 for C. zofingiensis, which were higher than those for other carbon sources tested and the control group. Incremental increase of light intensity instead of direct increase to 170 µE m?2s? prevented cell loss in both cultures. Co‐cultivation based on cell numbers (60% H. pluvialis and 40% C. zofingiensis) prevented population domination of one microalgae over the other. The biomass production rate of the co‐culture was higher (0.61 g L?1 day?1) in glucose‐enriched medium. The total carotenoid content of the co‐culture in the control culture was higher (0.83 mg total carotenoids g?1 cell) than that obtained in glucose‐enriched medium (0.54 mg total carotenoids g?1 cell) but not as high as the amounts reached in mono‐cultures. CONCLUSION: Total carotenoid content of the mono‐cultures gave higher yields in standard bold basal medium (BBM). Preliminary high performance liquid chromatography (HPLC) studies indicated a variation in the amounts of astaxanthin isomers produced. Further studies are in progress to determine the effects of carbon‐enriched media and co‐cultivation on the type of isomers and caretenoids produced. Copyright © 2010 Society of Chemical Industry 相似文献
47.
The art of mosaic has arisen thousands of years ago. Despite all those years and all the attention it has received till today, mosaic tiling is still being carried out manually and mosaic tiling processes have never been changed except the tool and material developments. 相似文献
48.
In this work, the minimization of the ripple in the relative change of the transfer function amplitude due to parameter variations is studied for the signal-flow graph of the state equations realizing all-pole second-order transfer function. First the measure for the ripple is defined and then branch transmittances minimizing the measure are found. the results obtained in this study can be used in all-pole active filter realizations with the minimum ripple measure. 相似文献
49.
The Data Locality of Work Stealing 总被引:1,自引:0,他引:1
This paper studies the data locality of the work-stealing scheduling algorithm on hardware-controlled shared-memory machines,
where movement of data to and from the cache is solely controlled by the hardware. We present lower and upper bounds on the
number of cache misses when using work stealing, and introduce a locality-guided work-stealing algorithm and its experimental
validation.
{As a lower bound, we show that a work-stealing application that exhibits good data locality on a uniprocessor may exhibit
poor data locality on a multiprocessor. In particular, we show a family of multithreaded computations G
n
whose members perform Θ(n) operations (work) and incur a constant number of cache misses on a uniprocessor, while even on two processors the total
number of cache misses soars to Ω(n) . On the other hand, we show a tight upper bound on the number of cache misses that nested-parallel computations, a large,
important class of computations, incur due to multiprocessing. In particular, for nested-parallel computations, we show that
on P processors a multiprocessor execution incurs an expected
more misses than the uniprocessor execution. Here m is the execution time of an instruction incurring a cache miss, s is the steal time, C is the size of cache, and T
∈
fty is the number of nodes on the longest chain of dependencies. Based on this we give strong execution time bounds for nested-parallel
computations using work stealing.}
For the second part of our results, we present a locality-guided work-stealing algorithm that improves the data locality
of multithreaded computations by allowing a thread to have an affinity for a processor. Our initial experiments on iterative
data-parallel applications show that the algorithm matches the performance of static-partitioning under traditional work loads
but improves the performance up to 50% over static partitioning under multiprogrammed work loads. Furthermore, locality-guided
work stealing improves the performance of work stealing up to 80%. 相似文献
50.
The limitations of the photolithography-based micromachining technologies defines the upper-bound on the performance and robustness of micromachined gyroscopes. Conventional gyroscope designs based on matching (or near-matching) the drive and sense modes are extremely sensitive to variations in oscillatory system parameters that shift the natural frequencies and introduce quadrature errors. Nonconventional design concepts have been reported that increase bandwidth to improve robustness, but with the expense of response gain reduction. This paper presents a new approach that may yield robust vibratory MEMS gyroscopes with better gain characteristics while retaining the wide bandwidth. The approach is based on utilizing multiple drive-mode oscillators with incrementally spaced resonance frequencies to achieve wide-bandwidth response in the drive-mode, leading to improved robustness to structural and thermal parameter fluctuations. Enhanced mode-decoupling is achieved by distributing the linear drive-mode oscillators radially and symmetrically, to form a multidirectional linear drive-mode and a torsional sense-mode; minimizing quadrature error and zero-rate output. The approach has been implemented on bulk-micromachined prototypes fabricated in a silicon-on-insulator (SOI)-based process, and experimentally demonstrated. 相似文献