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101.
Miscibility conditions and volumetric properties of solutions of poly(dimethylsiloxane) in supercritical carbon dioxide have been determined as a function of polymer molecular weight, polymer concentration, temperature, and pressure. Measurements have been conducted in a variable volume view cell equipped with an LVDT sensor to identify the position of a movable piston and thus the internal volume of the cell and consequently the density of the solution at a given pressure and temperature. The demixing data (in the form of P‐T curves for a given concentration, or as P‐x diagrams at a given T) and the density isotherms are presented for solutions of two polymer samples with different molecular weights (Mw = 38,600; Mw/Mn = 2.84 and Mw = 94,300; Mw/Mn = 3.01) at several concentrations in the range from 0.05 to 10 mass % over a temperature range from 302–425 K. Solution densities corresponding to the demixing points also have been identified. Representation of the demixing densities on the density isotherms, i.e., pressure‐density plots is a new methodology that gives a direct assessment of the volumetric expansion the solution must undergo before phase separation. The temperature–composition diagrams generated at selected pressures show that the poly(dimethylsiloxane) + CO2 solutions display both lower critical solution and upper critical solution type behavior. The lower critical solution temperature moves to lower temperatures and the upper critical solution temperature moves to higher temperatures with decreasing pressure and they eventually merge together at lower pressures forming an hourglass‐shaped region of immiscibility. This behavior is linked to the solvent quality of supercritical carbon dioxide that changes with pressure. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1397–1403, 2000 相似文献
102.
The aim of study was to investigate the effects of various curing protocols with quartz–tungsten halogen (QTH) or light‐emitting diode (LED) light‐curing units on the degree of conversion (% DC) of two dual‐cured core buildup resin composites. Two dual‐cured core buildup resin composites, Clearfil Dc Core Automix (CLF) and Grandio Core Dc (GR), were selected. Specimens were exposed to the polymerization protocols as follows: there was immediate photoactivation or photoactivation delayed by 2 or 5 min by a QTH or LED source, and one group was allowed to chemically polymerize and served as a control (n = 6). The % DC of the specimens was determined with attenuated total reflectance–Fourier transform infrared spectroscopy. The GR samples polymerized with QTH for the 5‐min‐delayed photoactivation had higher % DC values than those self‐cured, and the Clearfil Dc Core Automix (CLF) samples with immediate or delayed curing protocols with halogen yielded higher % DC values than the samples that were chemically polymerized. The comparison of the two resin composites polymerized with halogen showed a higher % DC for CLF than for GR in the 2‐min‐delayed photoactivation. On the other hand, when they were cured with LED, the % DC values of GR significantly increased after the 2‐min‐delayed photoactivation. In light of the results, it might be stated that CLF polymerized with QTH, could be the better option. GR provided adequate chemical polymerization; therefore, it might be useful in areas in which light curing is not possible. Clinicians should consider the polymerization characteristics of dual‐cured resin composites. The use of different composites may require the modification of the application procedures recommended by the manufacturer. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40560. 相似文献
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Zeynep Madak‐Erdogan Ping Gong Yiru Chen Zhao Liwen Xu Kinga U. Wrobel James A. Hartman Michelle Wang Anthony Cam Urszula T. Iwaniec Russell T. Turner Nathan C. Twaddle Daniel R. Doerge Ikhlas A. Khan John A. Katzenellenbogen Benita S. Katzenellenbogen William G. Helferich 《Molecular nutrition & food research》2016,60(2):369-380
106.
The abundance and spatial distribution of zooplankton at monthly intervals were studied in polluted Golden Horn Estuary (Istanbul, Turkey), from July 2006 to December 2007. Selected water quality parameters also were measured. The zooplankton community was characterized by the presence of freshwater, estuarine and marine species, with a total of 59 taxa. Rotifers were the most important fraction of the total zooplankton, comprising 36.52% of all the samples. The zooplankton exhibited seasonal patterns, with the highest abundance occurring in the summer (979 ind. L?1) and the lowest in the spring (856 ind. L?1). Rotifera was the most abundant group in the upper and middle estuary, whereas Copepoda usually reaches the maximum densities in the higher salinity waters in the lower estuary. The study results indicated that both the sampling time (seasons) and sampling sites jointly had significant effects on the zooplankton densities (manova P < 0.05), and horizontal patterns were related to electrical conductivity, water temperature, dissolved oxygen, suspended particulate matter, pH and chlorophyll a measured in the estuary. 相似文献
107.
Arno Behr Zeynep Bayrak Güner Samli Dilbar Yildiz Vedat Korkmaz Stefan Peitz Guido Stochniol 《化学工程与技术》2017,40(1):196-204
The catalyst decomposition in homogeneously catalyzed reactions is a very important factor that has been studied for the oligomerization of n‐butenes in a system of two liquid phases. A highly active catalyst [NiCl2(PMe3)2] was investigated with an emphasis on the long‐term catalyst activity using N‐methylpyrrole as a buffer. The recycling experiments indicated that this catalyst is viable for five runs. Furthermore, introducing aluminum chloride or an ionic liquid in small concentrations led to increased stability, though fine adjustments were necessary to arrive at optimal results. 相似文献
108.
Zeynep Tanes 《Behaviour & Information Technology》2017,36(10):1037-1045
Playing serious games may allow individuals to acquire essential disaster preparedness knowledge and skills. Playing such games repeatedly could generate self-efficacy, and consequently lead to behavioural intentions to take precautions. This study examines the effects of repetitive-play of an earthquake preparedness game on behavioural intentions, and the role of self-efficacy in mediating these positive outcomes. An experimental study was conducted, where repetitive-play was manipulated in a laboratory setting. An online self-administered survey was used to measure self-efficacy and behavioural intentions. Results showed that those in the repetitive-play condition had significant intentions to take precautions compared only to those in the no-play condition. The gradual increase in intentions from no-play to single-play to repetitive-play was not significant. Earthquake preparedness self-efficacy mediated the relationship between repetitive-play and behavioural intentions. Results of this study suggest that serious games should encourage repetitive-play while allowing players to progressively gain content self-efficacy, highlighting the important role of design and game features in serious games on risk communication. 相似文献
109.
Haleema Sadia Muhammad Zafar Mushtaq Ahmad Lubna Muhammad P. Z. Khan Ghulam Yaseen Muhammad I. Ali Shazia Sultana Omer Kilic Zeynep ahan Naveed Alam Qamar Abbas Abdul Ghani Saeeda Naz 《Microscopy research and technique》2020,83(3):259-267
The present study is focused on the detailed foliar epidermal anatomy of some selected wild edible fruits (WEFs) from Pakistan using light microscopy (LM) and scanning electron microscopy (SEM). The studied species are Ficus racemosa L., Solanum nigrum L., Capparis spinosa L., Physalis divaricata D.Don, Rosa moschata Herrm. and Ribes orientale Desf. collected from various localities of Pakistan. The objective of the present study is to investigate qualitative and quantitative anatomical characters for the identification and differentiation of collected wild edible fruits. The characters studied are shape and size of epidermal cells, anticlinal wall pattern, trichome type and shape, average number of stomata, length and width of stomata and pore. The detailed microscopic investigation and variations in the characters recorded have a key role in the determination and authentication of wild edible fruits. This study possesses great potential for plant taxonomists to further evaluate the species at molecular and genetic levels. 相似文献
110.
Culture-led regeneration of Istanbul waterfront: Golden Horn Cultural Valley Project 总被引：1，自引：0，他引：1
The regeneration of declining waterfronts has been one of the crucial tasks of urban policy since the 1970s; whereas culture has become an important theme as means for responding to the socio-economic decline that waterfronts have been facing through the re-functioning of abandoned factories and warehouses, the rehabilitation of historic neighborhoods and the utilization of events and amenities. At the same time, many academics are critical on the attempts to reform post-industrial spaces of consumption in creating privatized spaces and commodified cultures excluding social milieu. Within this context, the research attempts to discuss the contribution of culture-led approaches in the regeneration of Istanbul waterfront by using a case study of the Golden Horn Cultural Valley Project (GHCVP) as empirical evidence. The GHCVP is not only one of the most important indicators of wider governmental emphasis on culture as a way of reviving Istanbul’s waterfront; but also it provides major discussions and claims on the impact of these developments, especially those regarding the historic environment, local community and economy. The results of this research respond to questions about what makes waterfront regeneration a success and what role the culture-led approaches should play in the process of waterfront regeneration. 相似文献