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81.
The economic, social, ecological and environmental roles and benefits of forests are obvious and need no emphasis. Inefficient use of fuel wood is considered one of the important causes of deforestation. Use of more efficient improved cookstoves is proposed as one of the measures that can reduce demand for fuel wood and charcoal and help in lowering the annoying deforestation rate in many developing countries. During the 1980s and 1990s several programs aiming at testing and disseminating energy saving technologies were implemented in Sudan. One of these technologies was improved cookstoves, which was intended to increase the efficiency of using energy from biomass sources. This study is carried out to examine the adoption rate and the factors affecting adoption of improved cookstoves in Khartoum State. The study is based on primary data collected through personal interviews with husbands and wives in 300 randomly selected households. Regression analysis was used to analyze the data. The results showed that the device's adoption rate was very low. The improved cookstove's relative advantage, housewife's exposure to messages about improved cookstoves, educational level of the housewife and the average educational level of the female household's members had significant positive effect on the household's innovativeness regarding adoption of improved cookstove. Wife's age and the educational level of the husband had negative significant effects. In the Sudanese patriarchal society all the household domestic tasks, particularly food preparation and related activities, are considered women's responsibilities and all the decisions related to them are taken by women. Therefore, these results could be understood as a reflection of the division of labor, gender relations and decision-making process in the Sudanese household. 相似文献
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Mehmet Kaplan Fahrettin Yakuphanoglu Abdulkadir Yildiz 《Materials and Manufacturing Processes》2006,21(1):97-104
In this study, the effects of mold pressure variation on the microstructure, mechanical, oxidation behavior, and thermodynamics properties of an AlSi12CuNi alloy have been investigated by means of optical microcopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, differential thermal analysis, and thermo-gravimetric analysis techniques. It is observed that hardness and tensile strength of the alloys increase as die-casting mold pressure increases due to an improvement in the distribution pattern of secondary phases and reduction in porosity. Oxidation behavior parameters and thermodynamic parameters such as formation enthalpy, heat capacity, and entropy are determined from TGA and DTA. It is found that mold pressure also has a significant effect on the oxidation behavior and thermodynamic parameters. 相似文献
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Abdulkadir Çevik Radhwan Alzeebaree Ghassan Humur Anıl Niş Mehmet Eren Gülşan 《Ceramics International》2018,44(11):12253-12264
In this study, the effect of nano silica on the short term severe durability performance of fly ash based geopolymer concrete (GPC) specimens was investigated. Four types of GPC were produced with two types of low calcium fly ashes (FAI and FAII) with and without nano silica, and ordinary Portland cement concrete (OPC) concrete was also cast for reference. For the geopolymerization process, the alkaline activator has selected a mixture of sodium silicate solution (Na2SiO3) and sodium hydroxide solution (NaOH) with a ratio (Na2SiO3/ NaOH) of 2.5. Main objectives of the study were to investigate the effect of usability or replaceability of nano silica-based low calcium fly ash based geopolymer concretes instead of OPC concrete in structural applications and make a contribution to standardization process of the fly ash based geopolymer concrete. To achieve the goals, four types of geopolymer and OPC concretes were subjected to sulfuric acid (H2SO4), magnesium sulfate (MgSO4) and seawater (NaCl) solutions with concentrations of 5%, 5%, and 3.5%, respectively. Visual appearances and weight changes of the concretes under chemical environments were utilized for durability aspects. Compressive, splitting tensile and flexural strength tests were also performed on specimens to evaluate the mechanical performance under chemical environments. Results indicated that FAGPC concretes showed superior performance than OPC concrete under chemical attacks due to low calcium content. Amongst the chemical environments, sulfuric acid (H2SO4) was found to be the most dangerous environment for all concrete types. In addition, nano silica (NS) addition to FAGPC specimens improved both durability and residual mechanical strength due to the lower porosity and more dense structure. The FAIIGPC specimens including nano silica showed the superior mechanical performance under chemical environment. 相似文献
86.
Nur Aqilah Bt Fauzan Hafiz Abdul Mannan Rizwan Nasir Dzeti Farhah Bt Mohshim Hilmi Mukhtar 《化学工程与技术》2019,42(12):2608-2620
The application of thin‐film composite mixed‐matrix membranes (TFC‐MMMs) for gas separation is widely considered as an efficient separation technology. The principal methods for the preparation of TFC‐MMMs are dip‐coating, phase inversion, and interfacial polymerization comprising different types of support layers. These methods influence the CO2 permeation over the selective and support layers. A comprehensive review is provided for capturing new details of progress achieved in developing TFC‐MMMs with detailed performance of gas separation in the previous few years. Various preparation techniques of TFC‐MMMs and their effect on the gas separation performance of the prepared membranes are described. 相似文献
87.
Gamze Bozkurt Abdulkadir Özer Ayşe Bayrakçeken Yurtcan 《International Journal of Hydrogen Energy》2018,43(49):22205-22214
Hydrogen is an alternative and clean energy carrier, but there are still some production related problems. In this aspect, it is crucial to efficiently generate hydrogen from hydrogen rich materials such as sodium borohydride. In this study, Co3O4 supported Ni and Co catalysts are synthesized via microwave irradiation technique for hydrogen generation from sodium borohydride. In this context, firstly, Co3O4 support material is synthesized by chemical method. Then, Ni and Co catalysts are decorated onto Co3O4 support material by microwave irradiation-polyol method. Prepared catalysts and support material are characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma-mass spectrometer (ICP/MS). A new system is designed by our group in order to determine the activity of the prepared catalysts for hydrogen generation. The effects of different initial NaOH concentrations on hydrogen generation rate are investigated. It is observed that the rate of hydrogen generation increased with an increase in initial NaOH concentration. Co-Co3O4 catalyst at 10% NaOH initial concentration shows the highest hydrogen generation rate as 2823 ml/gcat.min. In summary, Co-based catalysts are exhibited more activity than Ni-based catalysts in terms of hydrogen generation. 相似文献
88.
Persistent left superior vena cava: Two case reports and a review from nephrologists’ perspective
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Tuncay Sahutoglu Tamer Sakaci Ekrem Kara Elbis Ahbap Taner Basturk Yener Koc Mustafa Sevinc Cuneyt Akgol Arzu Ozdemir Kayarlar Zuhal Atan Ucar Feyza Bayraktar Caglayan Nuri Baris Hasbal Perin Nazif Mahmoud Isleem Elif Sahutoglu Abdulkadir Unsal 《Hemodialysis international. International Symposium on Home Hemodialysis》2016,20(3):369-377
Thoracic venous anomalies without congenital heart anomalies are present in minority of the population, but they are frequent enough to be encountered while placing hemodialysis catheters through the jugular or subclavian veins. Persistent left superior vena cava is the most commonly seen anomaly and it is rarely noticed before the observation of an unusual course of hemodialysis catheter or guidewire on chest X‐ray. We present two patients with previously unspotted persistent left superior vena cava and uncomplicated hemodialysis catheter insertions through the internal jugular veins with good catheter functions. Review of the relevant literature from a nephrologists’ perspective with technical aspects is provided. 相似文献
89.
Structural, physical, magnetic and electrical properties of La-substituted W-type hexagonal ferrites
Mukhtar AhmadFaiza Aen M.U. IslamShahida B. Niazi M.U. Rana 《Ceramics International》2011,37(8):3691-3696
Lanthanum doped W-type hexaferrites BaZn2LaxFe16−xO27 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) were synthesized by co-precipitation and sintered at 1320 °C. The X-ray diffraction reveals W-type hexagonal structure with few traces of secondary phase. The decrease in grain size as a function of La-concentration is attributed to the fact that La acts as a grain inhibitor. The saturation magnetization and remanance decrease due to spin canting on B-sites. The increase in coercivity follows 1/r behavior where r is the radius of grain. The DC resistivity was observed to increase from 0.59 × 107 to 8.42 × 107 Ω cm with increasing La-contents due to the unavailability of Fe3+ ions. This enhancement in resistivity makes these materials promising candidates for use at high frequencies in order to reduce eddy current losses. 相似文献
90.