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排序方式: 共有171条查询结果,搜索用时 375 毫秒
91.
Victor Prajapati Tom Janssens Joachim John Jef Poortmans Robert Mertens 《Progress in Photovoltaics: Research and Applications》2013,21(5):980-985
Traditional POCl3 diffusion is performed in large diffusion furnaces heated to ~850 C and takes an hour long. This may be replaced by an implant and subsequent 90‐s rapid thermal annealing step (in a firing furnace) for the fabrication of p‐type passivated emitter rear contacted silicon solar cells. Implantation has long been deemed a technology too expensive for fabrication of silicon solar cells, but if coupled with innovative process flows as that which is mentioned in this paper, implantation has a fighting chance. An SiOx/SiNy rear side passivated p‐type wafer is implanted at the front with phosphorus. The implantation creates an inactive amorphous layer and a region of silicon full of interstitials and vacancies. The front side is then passivated using a plasma‐enhanced chemical vapor deposited SiNxHy. The wafer is placed in a firing furnace to achieve dopant activation. The hydrogen‐rich silicon nitride releases hydrogen that is diffused into the Si, the defect rich amorphous front side is immediately passivated by the readily available hydrogen; all the while, the amorphous silicon recrystallizes and dopants become electrically active. It is shown in this paper that the combination of this particular process flow leads to an efficient Si solar cell. Cell results on 160‐µm thick, 148.25‐cm2 Cz Si wafers with the use of the proposed traditional diffusion‐free process flow are up to 18.8% with a Voc of 638 mV, Jsc of 38.5 mA/cm2, and a fill factor of 76.6%. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
92.
Martijn A. J. Gillissen Tom T. Hoeben A. J. H. Spiering Jef A. J. M. Vekemans Anja R. A. Palmans E. W. Meijer 《Israel journal of chemistry》2011,51(10):1118-1127
A novel set of chiral self-assembling discotic molecules has been prepared based on two previously studied self-assembling C3-discotic systems, namely alkyl substituted benzene-1,3,5-tricarboxamides (alkyl-BTAs) and 3,3′-bis(acylamino)-2,2′-bipyridine substituted BTAs (BiPy-BTAs). By replacing one of the three bipyridyl side chains by an alkyl chain we have prepared a hybrid system that shows properties of both parent compounds. Due to the different packing parameters and mechanisms of self-assembly of the parent BTAs, one might expect a lack of ordering in such a hybrid system. However, we observe columnar mesophases and unique self-assembly behavior in solution. We propose that the solution self-assembly passes through three stages. First, disordered aggregates are formed that evolve into ordered aggregates via an isodesmic process. Finally, these ordered aggregates rearrange in a cooperative fashion into a higher ordered structure. Through the interplay between π–π interactions and H-bonding, the hybrid molecules combine the cooperative self-assembly behavior of alkyl-BTAs with the isodesmic behavior of BiPy-BTA discotics. This work shows that merging two systems with seemingly incompatible requirements can lead to new and complex self-assembly behavior. 相似文献
93.
Dr. Jakub Modranka Dr. Jiahong Li Dr. Anastasia Parchina Michiel Vanmeert Dr. Shrinivas Dumbre Dr. Mayla Salman Prof. Hannu Myllykallio Prof. Hubert F. Becker Roeland Vanhoutte Lia Margamuljana Hoai Nguyen Rania Abu El-Asrar Prof. Jef Rozenski Prof. Piet Herdewijn Dr. Steven De Jonghe Prof. Eveline Lescrinier 《ChemMedChem》2019,14(6):645-662
Since the discovery of a flavin-dependent thymidylate synthase (ThyX or FDTS) that is absent in humans but crucial for DNA biosynthesis in a diverse group of pathogens, the enzyme has been pursued for the development of new antibacterial agents against Mycobacterium tuberculosis, the causative agent of the widespread infectious disease tuberculosis (TB). In response to a growing need for more effective anti-TB drugs, we have built upon our previous screening efforts and report herein an optimization campaign of a novel series of inhibitors with a unique inhibition profile. The inhibitors display competitive inhibition toward the methylene tetrahydrofolate cofactor of ThyX, enabling us to generate a model of the compounds bound to their target, thus offering insight into their structure–activity relationships. 相似文献
94.
Wim Dewulf Florian Wagner Ellen Bracquené Jef R. Peeters Joost R. Duflou 《CIRP Annals》2019,68(1):29-32
Waste Electrical and Electronic Equipment (WEEE) comprises a complex mix of engineering plastic grades often containing flame retardants. Whereas post-shredder recycling strategies are widely implemented, considerably higher economic and environmental returns can be expected based on information-rich dismantling scenarios. This paper therefore presents the results of an extensive technological feasibility study on diversified recycling strategies for a dismantling based approach. Results of mechanical and flammability tests as well as injection moulding trials are moreover presented to show the quality and potential of the recycling strategies. Subsequently, the environmental impact reduction potential is assessed using Life Cycle Assessment. 相似文献
95.
Ji Zou Guo-Jun Zhang Jef Vleugels Omer Van der Biest 《Journal of the European Ceramic Society》2013,33(10):1609-1614
ZrB2–20 vol% SiC (ZS) ceramics based on ZrB2 starting powders obtained by different boro/carbo-thermal reductions involving ZrO2 + B4C, ZrO2 + B4C + C, and ZrO2 + B, were fully densified by hot pressing at 1900–2000 °C. The flexural strength of these ZS ceramics was measured from room temperature up to 1600 °C. At 1600 °C, the flexural strength of the ceramics is 460 ± 31, 471 ± 32 and 345 ± 11 MPa, respectively. The evolution of the strength as function of temperature is explained in terms of the differences in oxygen content, nature of fracture, grain sizes, grain boundary phases and microstructural defects. 相似文献
96.
The increasing demand for high-performance materials, in for example aerospace and biomedical industries, calls for more efficient and capable technologies. This paper describes a new technology, namely Mechano-Electrochemical Milling (MECM), which combines electrochemical machining (ECM) with a mechanical cutting process. The process behaviour has been investigated experimentally based on the machining of two Titanium alloys, Titanium grade 2 and Titanium grade 5. The material removal mechanism was investigated through analysis of the machined surface and removed material. Besides the slightly higher material removal rate in MECM compared to ECM, the MECM process results in more stable process conditions. 相似文献
97.
Tim Van De Gucht Wouter Saeys Jef Van Meensel Annelies Van Nuffel Jurgen Vangeyte Ludwig Lauwers 《Journal of dairy science》2018,101(1):637-648
Although prototypes of automatic lameness detection systems for dairy cattle exist, information about their economic value is lacking. In this paper, a conceptual and operational framework for simulating the farm-specific economic value of automatic lameness detection systems was developed and tested on 4 system types: walkover pressure plates, walkover pressure mats, camera systems, and accelerometers. The conceptual framework maps essential factors that determine economic value (e.g., lameness prevalence, incidence and duration, lameness costs, detection performance, and their relationships). The operational simulation model links treatment costs and avoided losses with detection results and farm-specific information, such as herd size and lameness status. Results show that detection performance, herd size, discount rate, and system lifespan have a large influence on economic value. In addition, lameness prevalence influences the economic value, stressing the importance of an adequate prior estimation of the on-farm prevalence. The simulations provide first estimates for the upper limits for purchase prices of automatic detection systems. The framework allowed for identification of knowledge gaps obstructing more accurate economic value estimation. These include insights in cost reductions due to early detection and treatment, and links between specific lameness causes and their related losses. Because this model provides insight in the trade-offs between automatic detection systems' performance and investment price, it is a valuable tool to guide future research and developments. 相似文献
98.
Toughness tailoring of yttria-doped zirconia ceramics 总被引:3,自引:0,他引:3
Bikramjit Basu Jef Vleugels Omer Van der Biest 《Materials Science and Engineering: A》2004,380(1-2):215-221
Despite the impressive development in understanding transformation toughening, tailoring the toughness of yttria-doped zirconia ceramics remained a major challenge. In our research, a simple but innovative route based on the mixing and hot pressing (under identical conditions) of zirconia powders with varying yttria content (3 and 0 mol%) is developed to investigate this critical issue. The experimental results clearly reveal that the fracture toughness of yttria-stabilized tetragonal zirconia polycrystalline (Y-TZP) ceramics can be tailored by careful mixing of co-precipitated and yttria-free zirconia starting powders. 相似文献
99.
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