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  • 1
    Language: English
    In: Engineering Structures, Feb, 2013, Vol.47, p.148(7)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.engstruct.2012.02.018 Byline: Xin Jia Keywords: RC hyperbolic cooling tower; Nonlinear finite element method; Material nonlinearity; Geometric nonlinearity; Cracking of concrete; Yielding of the reinforcement; Buckling; Ultimate load; Ultra-high-strength-fiber concrete; Imperfections Abstract: The failure mode of a previously analyzed reinforced concrete (RC) hyperbolic cooling tower is re-investigated by means of the Finite Element Method (FEM), however, with another computer program. Furthermore, the original design of this cooling tower is changed. The changes include use of ultra-high-strength-fiber concrete (UHSF-concrete), reduction of the thickness of the shell, and consideration of imperfections of the original geometry of the structure. The main conclusion drawn from the numerical results is that the cooling tower would still fail by loss of strength, characterized by the existence of an ultimate load and of yielding of the reinforcement. Author Affiliation: Institute for Mechanics of Materials and Structures, Vienna University of Technology, Austria Article Note: (dedication) Dedicated to Professor Herbert A. Mang on the occasion of his 70th birthday
    Keywords: Concretes -- Analysis ; Finite Element Method -- Analysis ; Cooling Systems -- Analysis
    ISSN: 0141-0296
    Source: Cengage Learning, Inc.
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  • 2
    Language: English
    In: Chemosphere, April 2012, Vol.87(5), pp.477-482
    Description: ► A concentration of 10 μg L BDE-209 suppressed the sorption of BDE-47. ► BDE-47 caused no competitive effect on BDE-209 sorption. ► Desorption hysteresis was observed in all cases in both single and binary systems. ► BDE-209 impacted BDE-47 desorption in different ways for different soils. Three loamy-clay soil samples (LC1-3) with different properties were collected as the geosorbents to preliminarily investigate the sorption and desorption of 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) in single system and binary system with the presence of decabromodiphenyl ether (BDE-209), which can provide information in order to further understand the sorption mechanisms and evaluate the adsorption sites. A concentration of 10 μg L BDE-209 suppressed the sorption of BDE-47, and the trend became more and more significant with the increase of BDE-47 equilibrium concentration, however, BDE-47 caused no competitive effect on BDE-209 sorption, which was related with the better accessibility of more hydrophobic molecules to adsorption sites. In the binary system, nonlinearity of the BDE-47 sorption isotherms for the three samples changed in different ways, which originated from the varied soil properties. Desorption hysteresis was observed in all cases, which was estimated due to irreversible surface adsorption between sorbent and sorbate. BDE-209 made desorption of BDE-47 more hysteretic from soil samples, which was estimated to be ascribed to the accelerated sorbent state transition and new sites creation caused by BDE-209 sorption.
    Keywords: Bde-47 ; Binary-Solute System ; Sorption ; Desorption ; Chemistry ; Ecology
    ISSN: 0045-6535
    E-ISSN: 1879-1298
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  • 3
    Language: English
    In: Chemosphere, 2011, Vol.84(3), pp.342-347
    Description: ► DDTs contamination was investigated in paint factory sites and shipyard sites. ► DDT containing antifouling paint served as important fresh sources for DDT pollution. ► Compared with paint factory sites, shipyard sites were more seriously contaminated ► History and capacity of paint production and use largely affected DDTs level. This study provides the first intensive investigation of Dichlorodiphenyltrichloroethanes (DDT) distribution in typical paint factories and shipyards in China where DDT containing antifouling paint were mass produced and used respectively. DDTs were analyzed in soil, sludge and sediment samples collected from three major paint factories and two shipyards. The results showed that the total DDTs concentrations detected in paint factory and shipyard sites ranged from 0.06 to 8387.24 mg kg . In comparison with paint factory sites, the shipyard sites were much more seriously contaminated. However, for both kinds of sites, the DDTs level was found to be largely affected by history and capacity of production and use of DDT containing antifouling paint. (DDE + DDD)/DDT ratios indicated that DDT containing antifouling paint could serve as important fresh input sources for DDTs. It can be seen that most samples in shipyards were in ranges where heavy contamination and potential ecological risk were identified.
    Keywords: Dichlorodiphenyltrichloroethanes (Ddt) ; Environmental Pollution ; Paint Factory ; Shipyard ; Chemistry ; Ecology
    ISSN: 0045-6535
    E-ISSN: 1879-1298
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  • 4
    Language: English
    In: Oikos, acta oecologica Scandinavica, 2011, Vol.120(3), pp.472-480
    Description: Recent years have seen a growing body of evidence showing that plant competition and facilitation usually operate simultaneously to drive population dynamics, community structure and ecosystem functions. However, the potential role of facilitation in spatial patterning of plant populations has rarely been explicitly examined. We used a ‘zone-of-influence' model to explore how facilitation interacts with competition and abiotic stress to determine the spatial patterning of populations during density-dependent mortality. Model simulations revealed that started with the same clustered pattern, the final pattern of simulated populations depended strongly on the interaction among facilitation, stress level and size-symmetry of competition. Asymmetric competition consistently led to immediate and non-random mortality towards regularity, thus rapidly decayed the initially clustered pattern to final patterns of small-scale regularity and large-scale randomness. The role of symmetric competition in decaying the clustered pattern increased with abiotic stress because stress-induced reductions in plants' growth rates can make individuals in high-density clusters more likely to die even from symmetric competition. Facilitation played a clear role in counteracting the effect of stress, thus tended to maintain the degree of clustering of the pattern during density-dependent mortality. This is because the amelioration of harsh conditions by neighboring plants relieved the reductions in plant growth due to competition, thus slowed down and reduced the mortality inside clusters (relative to that outside clusters). Moreover, the effect of facilitation appeared to increase with abiotic stress. Our results indicate that facilitation among neighboring plants should partially be responsible for clustered population spatial patterns observed in stressful environments, even though its contribution relative to other factors (e.g. local dispersal and environmental heterogeneity) remains to be evaluated. In addition, the potential influence of facilitation on self-thinning trajectory should be explicitly examined in future modeling and experimental studies considering its effects on density-dependent mortality. ; Includes references ; p. 472-480.
    Keywords: Plant Populations -- Models ; Plant Populations -- Health Aspects ; Plant Populations -- Analysis;
    ISSN: 0030-1299
    E-ISSN: 16000706
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  • 5
    In: Journal of Polymer Science Part A: Polymer Chemistry, 01 July 2014, Vol.52(13), pp.1807-1814
    Description: A nondestructive method was developed for grafting and retrieving polymer brushes from single‐walled carbon nanotubes (SWCNT)s based on mussel‐inspired chemistry. Thermo‐responsive polymer brushes were grafted on SWCNTs by coating the tubes with polydopamine as a reactive underlayer and sequential surface‐initiated atom transfer radical polymerization of oligo(ethylene glycol) methacrylate (OEGMA,  = 475) and 2‐(2'‐methoxyethoxy)ethyl methacrylate (MEO2MA). Copolymer brushes were retrieved from the SWCNTs using 1 M NaOH to destroy the crosslinked polydopamine coating, and after that, the pristine properties of the SWCNTs were preserved. The low critical solution temperature (LCST) and molecular weight of the copolymer were measured using a nephelometer and gel permeation chromatograph, respectively. The loading and release behavior of Rhodamine 6G on responsive polymer‐grafted SWCNTs demonstrates that the copolymer brushes confer the SWCNTs an LCST dependence. This method can accurately confirm the molecular weights and polydispersity of stimuli‐responsive polymers grafted on any other nanoparticles and predict their controlled release behavior. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. , , 1807–1814 An easy and reliable method is developed to tune the low critical solution temperatures (LCSTs) of thermo‐responsive polymer brushes grafted on single‐walled carbon nanotubes (SWCNTs), and to study the LCST‐dependent drug‐loading and drug‐release properties of these polymer‐modified SWCNTs. The copolymers grafted on SWCNTs are retrieved by 1 M NaOH to evaluate their molecular weights and LCSTs. Additionally, the pristine properties of SWCNTs are preserved.
    Keywords: Single‐Walled Carbon Nanotubes ; Polydopamine ; Thermo‐Responsive Polymer Brushes ; Mussel‐Inspired Chemistry ; Surface‐Initiated Atom Transfer Radical Polymerization
    ISSN: 0887-624X
    E-ISSN: 1099-0518
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  • 6
    Language: English
    In: Journal of Environmental Management, March 1, Vol.150, p.420(7)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jenvman.2014.12.022 Byline: Jia Xin, Jun Han, Xilai Zheng, Haibing Shao, Olaf Kolditz Abstract: This report focuses on the enhancement in trichloroethylene (TCE) removal from contaminated groundwater using xanthan gum (XG)-modified, microscale, zero-valent iron (mZVI). Compared with bare mZVI, XG-coated mZVI increased the TCE removal efficiency by 30.37% over a 480-h experimental period. Because the TCE removal is attributed to both sorption and reduction processes, the contributions from sorption and reduction were separately investigated to determine the mechanism of XG on TCE removal using mZVI. The results showed that the TCE sorption capacity of mZVI was lower in the presence of XG, whereas the TCE reduction capacity was significantly increased. The FTIR spectra confirmed that XG, which is rich in hydrophilic functional groups, was adsorbed onto the iron surface through intermolecular hydrogen bonds, which competitively repelled the sorption and mass transfer of TCE toward reactive sites. The variations in the pH, Eh, and Fe.sup.2+ concentration as functions of the reaction time were recorded and indicated that XG buffered the solution pH, inhibited surface passivation, and promoted TCE reduction by mZVI. Overall, the XG-modified mZVI was considered to be potentially effective for the in-situ remediation of TCE contaminated groundwater due to its high stability and dechlorination reactivity. Author Affiliation: (a) College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China (b) Helmholtz Center for Environmental Research UFZ/TU Dresden, Leipzig 034202, Germany Article History: Received 17 September 2014; Revised 5 December 2014; Accepted 10 December 2014
    Keywords: Groundwater ; Polysaccharides
    ISSN: 0301-4797
    Source: Cengage Learning, Inc.
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  • 7
    Language: English
    In: Analytical Chemistry, August 18, 2015, Vol.87(16), p.8181(5)
    Description: The article describes the development of a new approach for global fatty acid (FA) profiling and identification for high-performance liquid chromatography-multiple reaction monitoring (HPLC-MRM) FA data mining. A high identification efficiency (greater than 75%) was achieved when 96 FA species were identified in plasma.
    Keywords: Fatty Acids – Identification and Classification ; Liquid Chromatography – Usage ; Blood Plasma – Analysis
    ISSN: 0003-2700
    Source: Cengage Learning, Inc.
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  • 8
    Language: English
    In: Journal of the American Chemical Society, 24 September 2014, Vol.136(38), pp.13186-9
    Description: An iron-catalyzed diastereoselective intermolecular olefin amino-oxygenation reaction is reported, which proceeds via an iron-nitrenoid generated by the N-O bond cleavage of a functionalized hydroxylamine. In this reaction, a bench-stable hydroxylamine derivative is used as the amination reagent and oxidant. This method tolerates a range of synthetically valuable substrates that have been all incompatible with existing amino-oxygenation methods. It can also provide amino alcohol derivatives with regio- and stereochemical arrays complementary to known amino-oxygenation methods.
    Keywords: Alkenes -- Chemistry ; Hydroxylamines -- Chemistry ; Iron -- Chemistry ; Oxidants -- Chemistry
    ISSN: 00027863
    E-ISSN: 1520-5126
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  • 9
    Language: English
    In: Journal of Alloys and Compounds, Dec 15, 2012, Vol.544, p.125(4)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jallcom.2012.07.135 Byline: Xiang-Ping Jiang, Xin-Jia Wang, Jia-Xin Wen, Chao Chen, Na Tu, Xiao-Hong Li Keywords: Bismuth layer-structured; Piezoelectric ceramics; Microstructure; Na.sub.0.25K.sub.0.25Bi.sub.2.5Nb.sub.2O.sub.9 Abstract: a* In this work, Mn-modified Na.sub.0.25K.sub.0.25Bi.sub.2.5Nb.sub.2O.sub.9 ceramics were prepared by a traditional solid-state reaction. a* Mn ions entered into the Na.sub.0.25K.sub.0.25Bi.sub.2.5Nb.sub.2O.sub.9 lattices to form a solid solution. a* The electrical properties of NKBN-based ceramics are improved significantly by the addition of Mn. a* The optimized properties of the ceramics: d.sub.33 =25 pC/N, Q.sub.m =2817, P.sub.r =14.50 [mu]C/cm.sup.2, T.sub.c =643[degrees]C. Author Affiliation: Jiangxi Key Laboratory of Advanced Ceramic Materials, Department of Material Science and Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333001, China Article History: Received 19 July 2012; Accepted 29 July 2012
    Keywords: Bismuth -- Analysis ; Bismuth -- Electric Properties ; Ceramics -- Analysis ; Ceramics -- Electric Properties
    ISSN: 0925-8388
    Source: Cengage Learning, Inc.
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  • 10
    Language: English
    In: Water Research, 01 September 2016, Vol.100, pp.80-87
    Description: Application of microscale zero-valent iron (mZVI) is a promising technology for in-situ contaminated groundwater remediation; however, its longevity is negatively impacted by surface passivation, especially in saline groundwater. In this study, the aging behavior of mZVI particles was investigated in three media (milli-Q water, fresh groundwater and saline groundwater) using batch experiments to evaluate their potential corrosion and passivation performance under different field conditions. The results indicated that mZVI was reactive for 0–7 days of exposure to water and then gradually lost H -generating capacity over the next hundred days in all of the tested media. In comparison, mZVI in saline groundwater exhibited the fastest corrosion rate during the early phase (0–7 d), followed by the sharpest kinetic constant decline in the latter phases. The SEM-EDS and XPS analyses demonstrated that in the saline groundwater, a thin and compact oxide film was immediately formed on the surface and significantly shielded the iron reactive site. Nevertheless, in fresh groundwater and milli-Q water, a passive layer composed of loosely and unevenly distributed precipitates slowly formed, with abundant reactive sites available to support continuous iron corrosion. These findings provide insight into the molecular-scale mechanism that governs mZVI passivation and provide implications for long-term mZVI application in saline contaminated groundwater.
    Keywords: Microscale Zero-Valent Iron (Mzvi) ; Aging ; Passivation ; Hydrogen Production ; Saline Groundwater ; Engineering
    ISSN: 0043-1354
    E-ISSN: 1879-2448
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