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排序方式: 共有107条查询结果,搜索用时 0 毫秒
1.
G. Agostinelli A. Delabie P. Vitanov Z. Alexieva H.F.W. Dekkers S. De Wolf G. Beaucarne 《Solar Energy Materials & Solar Cells》2006,90(18-19):3438-3443
Surface recombination velocities as low as 10 cm/s have been obtained by treated atomic layer deposition (ALD) of Al2O3 layers on p-type CZ silicon wafers. Low surface recombination is achieved by means of field induced surface passivation due to a high density of negative charges stored at the interface. In comparison to a diffused back surface field, an external field source allows for higher band bending, that is, a better performance. While this process yields state of the art results, it is not suited for large-scale production. Preliminary results on an industrially viable, alternative process based on a pseudo-binary system containing Al2O3 are presented, too. With this process, surface recombination velocities of 500–1000 cm/s have been attained on mc-Si wafers. 相似文献
2.
Alkema WB Hensgens CM Snijder HJ Keizer E Dijkstra BW Janssen DB 《Protein engineering, design & selection : PEDS》2004,17(5):473-480
Penicillin acylase catalyses the condensation of Calpha-substituted phenylacetic acids with beta-lactam nucleophiles, producing semi-synthetic beta-lactam antibiotics. For efficient synthesis a low affinity for phenylacetic acid and a high affinity for Calpha-substituted phenylacetic acid derivatives is desirable. We made three active site mutants, alphaF146Y, betaF24A and alphaF146Y/betaF24A, which all had a 2- to 10-fold higher affinity for Calpha-substituted compounds than wild-type enzyme. In addition, betaF24A had a 20-fold reduced affinity for phenylacetic acid. The molecular basis of the improved properties was investigated by X-ray crystallography. These studies showed that the higher affinity of alphaF146Y for (R)-alpha-methylphenylacetic acid can be explained by van der Waals interactions between alphaY146:OH and the Calpha-substituent. The betaF24A mutation causes an opening of the phenylacetic acid binding site. Only (R)-alpha-methylphenylacetic acid, but not phenylacetic acid, induces a conformation with the ligand tightly bound, explaining the weak binding of phenylacetic acid. A comparison of the betaF24A structure with other open conformations of penicillin acylase showed that betaF24 has a fixed position, whereas alphaF146 acts as a flexible lid on the binding site and reorients its position to achieve optimal substrate binding. 相似文献
3.
Origin and Processing Methods Slightly Affect Allergenic Characteristics of Cashew Nuts (Anacardium occidentale) 下载免费PDF全文
Marit Reitsma Shanna Bastiaan‐Net Lutske Sijbrandij Evelien de Weert Stefano Sforza Roy Gerth van Wijk Huub F. J. Savelkoul Nicolette W. de Jong Harry J. Wichers 《Journal of food science》2018,83(4):1153-1164
The protein content and allergen composition was studied of cashews from 8 different origins (Benin, Brazil, Ghana, India, Ivory Coast, Mozambique, Tanzania, Vietnam), subjected to different in‐shell heat treatments (steamed, fried, drum‐roasted). On 2D electrophoresis, 9 isoforms of Ana o 1, 29 isoforms of Ana o 2 (11 of the acidic subunit, 18 of the basic subunit), and 8 isoforms of the large subunit of Ana o 3 were tentatively identified. Based on 1D and 2D electrophoresis, no difference in allergen content (Ana o 1, 2, 3) was detected between the cashews of different origins (P > 0.5), some small but significant differences were detected in allergen solubility between differently heated cashews. No major differences in N‐ and C‐terminal microheterogeneity of Ana o 3 were detected between cashews of different origins. Between the different heat treatments, no difference was detected in glycation, pepsin digestibility, or IgE binding of the cashew proteins. 相似文献
4.
Effects of growth hormone, insulin-like growth factor-I, and cortisol on periparturient antibody response profiles of dairy cattle 总被引:2,自引:0,他引:2
The objectives of this study were to determine hormone and antibody response profiles from the prepartum period to peak lactation, and evaluate potential immunomodulatory effects of the classic endocrine hormones, growth hormone (GH), insulin-like growth factor-I (IGF-I) and cortisol. Specifically, 33 Holstein cows were immunized with ovalbumin (OVA) and Escherichia coli J5 at weeks -8 and -3 prior to parturition. At parturition (week 0), cows received an additional immunization of OVA. Blood was collected at weeks -8, -3, 0, 3 and 6 relative to parturition and various samples were used to determine plasma hormone concentration, serum immunoglobulin (Ig), and specific antibody response to OVA and E. coli. Colostrum and milk samples were also collected post-parturition to monitor local immunoglobulin and antibody responses. Results indicated that not all periparturient cows exhibited depressed immune response, and that antibody response to OVA could be used to partition cows into 3 groups recognizing animals with sustained measurable antibody response before and after parturition (Group 1), animals which responded poorly to immunization at parturition (Group 2), and animals which did not respond to immunizations at week -3 or parturition (Group 3). Cows with the highest antibody response to OVA (Group 1) also tended (P < or = 0.10) to have the highest response to E. coli J5 at parturition and had the lowest incidence of disease, particularly mastitis. Antibody response to OVA measured in milk tended to be higher in Group 1 cows, particularly at week 0 (P < or = 0.06) compared to cows of Group 3. IGF-I was higher (P < or = 0.05) in cows of Group 1 than Group 3 at peak lactation (week 6). 相似文献
5.
The effect of varying the low-density polyethylene content and the polystyrenepolyethylene block co-polymer content on the rates of craze initiation and craze growth in polystyrene/low-density polyethylene blends has been studied. it was found that the parameters in the Eyring rate coefficients for craze initiation and craze growth are not dependent on the low-density polyethylene content. However, the rates of craze initiation increased with increasing low-density polyethylene content. This is explained tentatively by a new model for craze initiation. It is argued that effective crazes are only formed within clusters of low-density polyethylene particles that have overlapping stress-concentration fields. The dependence of the rate of craze initiation on the volume-fraction of dispersed phase that follows from this cluster model is qualitatively in agreement with experimental results. PS-PE co-polymer addition gives rise to changes in the Eyring parameters of the rate coefficients of craze initiation and craze growth. This may be a consequence of changes in morphology near the interface and of the different stress state at the interface. 相似文献
6.
High impact strength poly(phenylene oxide)-polyamide blends can be prepared by chemically coupling the two components and
incorporating a rubbery impact modifier in the resin. The resulting materials exhibit a distinctive morphology in which the
rubber is selectively incorporated in the dispersed poly(phenylene oxide) phase. In this paper both the structure and toughening
mechanisms in these blends are examined. An analysis of their deformation behaviour is presented in a companion paper. 相似文献
7.
Summary In this communication the results of a series of recent studies of the morphology and deformation behavior of toughened poly(butylene terephthalate) (PBT)/BPA polycarbonate (PC) blends are briefly summarized. Several papers containing a more detailed account are currently in press (1–3). Among the unique morphological features of these blends are the consistent isolation of the core/shell impact modifier (IM) in the PC phase and the crystallization and phase separation of the PBT from the partially miscible PBT/PC melt on slow cooling. DSC studies provide corroborating evidence for melt miscibility of the two resins. The blends deform through a combination of cavitation and shear processes. In all cases cavitation occurs exclusively within the IM particles and is suppressed at higher PC concentrations and elevated temperatures. 相似文献
8.
Machteld van den Broek Evelien Brederode Andrea Ramírez Leslie Kramers Muriel van der Kuip Ton Wildenborg Wim Turkenburg André Faaij 《Environmental Modelling & Software》2010,25(12):1754-1768
Large-scale deployment of carbon capture and storage needs a dedicated infrastructure. Planning and designing of this infrastructure require incorporation of both temporal and spatial aspects. In this study, a toolbox has been developed that integrates ArcGIS, a geographical information system with spatial and routing functions, and MARKAL, an energy bottom-up model based on linear optimization. Application of this toolbox led to blueprints of a CO2 infrastructure in the Netherlands. The results show that in a scenario with 20% and 50% CO2 emissions reduction targets compared to their 1990 level in respectively 2020 and 2050, an infrastructure of around 600 km of CO2 trunklines may need to be built before 2020. Investment costs for the pipeline construction and the storage site development amount to around 720 m€ and 340 m€, respectively. The results also show the implication of policy choices such as allowing or prohibiting CO2 storage onshore on CO2 Capture and Storage (CCS) and infrastructure development. This paper illustrates how the ArcGIS/MARKAL-based toolbox can provide insights into a CCS infrastructure development, and support policy makers by giving concrete blueprints over time with respect to scale, pipeline trajectories, and deployment of individual storage sites. 相似文献
9.
Wouter M.J. Achten Joana Almeida Vincent Fobelets Evelien Bolle Erik Mathijs Virendra P. Singh Dina N. Tewari Louis V. Verchot Bart Muys 《Applied Energy》2010
Since 2003 India has been actively promoting the cultivation of Jatropha on unproductive and degraded lands (wastelands) for the production of biodiesel suitable as transportation fuel. In this paper the life cycle energy balance, global warming potential, acidification potential, eutrophication potential and land use impact on ecosystem quality is evaluated for a small scale, low-input Jatropha biodiesel system established on wasteland in rural India. In addition to the life cycle assessment of the case at hand, the environmental performance of the same system expanded with a biogas installation digesting seed cake was quantified. The environmental impacts were compared to the life cycle impacts of a fossil fuel reference system delivering the same amount of products and functions as the Jatropha biodiesel system under research. The results show that the production and use of Jatropha biodiesel triggers an 82% decrease in non-renewable energy requirement (Net Energy Ratio, NER = 1.85) and a 55% reduction in global warming potential (GWP) compared to the reference fossil-fuel based system. However, there is an increase in acidification (49%) and eutrophication (430%) from the Jatropha system relative to the reference case. Although adding biogas production to the system boosts the energy efficiency of the system (NER = 3.40), the GWP reduction would not increase (51%) due to additional CH4 emissions. For the land use impact, Jatropha improved the structural ecosystem quality when planted on wasteland, but reduced the functional ecosystem quality. Fertilizer application (mainly N) is an important contributor to most negative impact categories. Optimizing fertilization, agronomic practices and genetics are the major system improvement options. 相似文献
10.
Bellemans Inge De Wilde Evelien Blanpain Bart Moelans Nele Verbeken Kim 《Metallurgical and Materials Transactions B》2017,48(6):3058-3073
Metallurgical and Materials Transactions B - This study investigates the origin of mechanically entrained metal droplets in liquid slag due to their interaction with solid spinel particles. Two... 相似文献