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Formation of Water Quality of Surface Water Bodies Used in the Material Processing
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作者 Tatyana Lyubimova Anatoly Lepikhin +2 位作者 Yanina Parshakova Irina Zayakina Alibek Issakhov 《Fluid Dynamics & Materials Processing》 EI 2024年第4期815-828,共14页
In the process of production or processing of materials by various methods,there is a need for a large volume of water of the required quality.Today in many regions of the world,there is an acute problem of providing ... In the process of production or processing of materials by various methods,there is a need for a large volume of water of the required quality.Today in many regions of the world,there is an acute problem of providing industry with water of a required quality.Its solution is an urgent and difficult task.The water quality of surface water bodies is formed by a combination of a large number of both natural and anthropogenic factors,and is often significantly heterogeneous not only in the water area,but also in depth.As a rule,the water supply of large industrial enterprises is located along the river network.Mergers are the most important nodes of river systems.Understanding the mechanism of transport of pollutants at the confluence of rivers is critical for assessing water quality.In recent years,thanks to the data of satellite images,the interest of researchers in the phenomenon of mixing the waters of merging rivers has increased.The nature of the merger is influenced by the formation of transverse circulation.Within the framework of this work,a study of vorticity,as well as the width of the mixing zone,depending on the distance from the confluence,the speeds of the merging rivers and the angle of confluence was carried out.Since the consumer properties of water are largely determined by its chemical and physical indicators,the intensity of mixing,determined largely by the nature of the secondary circulation,is of fundamental importance for assessing the distribution of hydrochemical indicators of water quality in the mixing zone.These characteristics are important not only for organizing water intake for drinking and technical purposes with the best consumer properties,but also for organizing an effective monitoring system for confluence zones. 展开更多
关键词 Water for material processing water quality formation of transverse circulation
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Effects of Functional Organic Materials on Morphological Indexes,Quality and Yield of Watermelon
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作者 Kun CHEN Shuying CHEN +1 位作者 Tao JIANG Pan ZHANG 《Agricultural Biotechnology》 2024年第3期8-10,共3页
[Objectives]This study was conducted to explore suitable organic compound application models for watermelon growth.[Methods]With watermelon hybrid material"M22×P18"as the test material,the effects of fo... [Objectives]This study was conducted to explore suitable organic compound application models for watermelon growth.[Methods]With watermelon hybrid material"M22×P18"as the test material,the effects of four functional organic materials,namely garlic straw treatment(T_(1)),onion straw treatment(T_(2)),garlic straw+sheep manure treatment(T_(3))and onion straw+chicken manure treatment(T_(4)),on the morphological indexes,yield and quality of watermelon were investigated.[Results]Different functional organic materials had different effects on morphological indexes,yield and quality of watermelon.The morphological indexes,nutritional quality indexes and yield of watermelon treated with garlic straw and sheep manure compound(T_(3))and onion straw and chicken manure compound(T_(4))were significantly higher than those treated simply with garlic straw(T_(1))and onion straw(T_(2)),and T_(3)performed relatively better.Compared with treatment T_(2),T_(3)showed a stem diameter,vine length and leaf number increasing by 43.05%,46.69%and 40.77%respectively,central sugar and side sugar contents increasing by 11.72%and 21.90%respectively,and a yield increasing by 42.91%,with significant differences from T_(2).[Conclusions]This study provides technical support for high-quality and high-yielding cultivation of watermelon. 展开更多
关键词 Organic materials WATERMELON Morphological index quality YIELD
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Effect of Different Mulch Materials on Yield and Nutrition Profile of Common Capsicum (Capsicum annuum) Cultivars in Bangladesh
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作者 Prince Biswas Md. Abubakar Siddik +5 位作者 Md. Shariful Islam Mohammad Zahir Ullah Md. Shamsuzzoha Hasina Akter Akm Maksudul Alam Mominul Hauque Robin 《Agricultural Sciences》 2024年第2期246-255,共10页
Capsicum is a nutritious vegetable and its cultivation in farms is getting popular in Bangladesh. Although many efforts have lain to explore better yielding and nutritionally rich cultivars with suitable modern cultiv... Capsicum is a nutritious vegetable and its cultivation in farms is getting popular in Bangladesh. Although many efforts have lain to explore better yielding and nutritionally rich cultivars with suitable modern cultivation techniques but still have to find the desired outcome. Thus, it’s necessary to conduct further research to identify the high-yielding and nutritious capsicum cultivars in Bangladesh. An experiment was conducted from July 2021 to June 2022 at the Bangladesh Institute of Research and Training on Applied Nutrition (BIRTAN) research field with three cultivars of capsicum: B<sub>0</sub> = California Wonder, B<sub>1</sub> = BARI Misti Morich-1 and B<sub>2</sub> = BARI Misti Morich-2 and three mulching: T<sub>0</sub> = No mulching, T<sub>1</sub> = Water hyacinth, T<sub>2</sub> = Poly Mulching in randomized complete block design with three replications to identify better quality capsicum cultivar and suitable mulching material. Among cultivars the BARI Misti Morich-2 (B<sub>2</sub>) showed increased agronomic parameters like number of branches and effective branches per plant, leaves length and width, consequently yield and yield contributing traits were also enhanced like fruits per plant, fruit length, fruit diameter and yield per plant (25.97%, 4.54%, 3.64% and 21.43%, respectively). Poly Mulching (T<sub>2</sub>) increased agronomic traits, yield traits and yield (0.61 kg) than BARI Misti Morich-1 (T<sub>1</sub>). The combined effect of B<sub>2</sub>T<sub>2</sub> increased the number of branches per plant, effective branches per plant, leaves length and breadth by 40%, 90%, 15.57% and 26.22%, respectively, hence resulting in an increased yield of 20%. BARI Misti Morich-2 cultivar showed an increase in Fe, Zn and Vitamin-C content of 26.24% and 23.10%, 8.82% and 5.14%, and 6.03% and 5.74% than B0 and B1 cultivars, respectively. Therefore, BARI Misti Morich-2 exhibited the improved agronomic, yield and nutritional traits of capsicum under poly mulching among other cultivars in Bangladesh. 展开更多
关键词 Capsicum Cultivars Mulch materials YIELD Yield Contributing Traits Nutritional quality
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Effect of mechanical anisotropy on material removal rate and surface quality during polishing CdZnTe wafers 被引量:1
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作者 LI Yan JIE Wanqi +1 位作者 KANG Renke GAO Hang 《Rare Metals》 SCIE EI CAS CSCD 2011年第4期381-386,共6页
The mechanical characters of CdZnTe crystal were investigated by nanoscratch tests, and the effects of mechanical anisotropy on the material removal rate and surface quality were studied by polishing tests. There is a... The mechanical characters of CdZnTe crystal were investigated by nanoscratch tests, and the effects of mechanical anisotropy on the material removal rate and surface quality were studied by polishing tests. There is a peak of frictional coefficient at the early stage of scratch, and increasing the vertical force will result in the increase of peak value correspondingly. The fluctuation phenomenon of frictional coefficient is generated at high vertical force. The lateral forces show the apparent twofold and threefold symmetries on (110) and (111) planes, respectively. To obtain high surface quality, low polishing pressure and hard direction (〈 T10 〉 directions on (110) plane and 〈 112 〉 directions on (111) plane) should be selected, and to achieve high material removal rate, high polishing pressure and soft direction (〈001〉 directions on (110) plane and 〈 121 〉 directions on (111) plane) should be selected. 展开更多
关键词 cadmium compounds single crystals nanoscratch tests frictional coefficient material removal rate surface quality ANISOTROPY
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Hydration mechanism of low quality fly ash in cement-based materials 被引量:10
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作者 刘数华 孔亚宁 王露 《Journal of Central South University》 SCIE EI CAS 2014年第11期4360-4367,共8页
The hydration mechanism of low quality fly ash in cement-based materials was investigated. The hydration heat of the composite cementitious materials was determined by isothermal calorimetry, and the hydration product... The hydration mechanism of low quality fly ash in cement-based materials was investigated. The hydration heat of the composite cementitious materials was determined by isothermal calorimetry, and the hydration products, quantity, pore structure and morphology were measured by X-ray diffraction(XRD), thermalgravity-differential thermal analysis(TG-DTA), mercury intrusion porosimetry(MIP) and scanning electron microscopy(SEM), respectively. The results indicate that grinding could not only improve the physical properties of the low quality fly ash on particle effect, but also improve hydration properties of the cementitious system from various aspects compared with raw low quality fly ash(RLFA). At the early stage of hydration, the low quanlity fly ash acts as almost inert material; but then at the later stage, high chemical activity, especially for ground low quality fly ash(GLFA), could be observed. It can accelerate the formation of hydration products containing more chemical bonded water, resulting in higher degree of cement hydration, thus denser microstructure and more reasonable pore size distribution, but the hydration heat in total is reduced. It can also delay the induction period, but the accelerating period is shortened and there is little influence on the second exothermic peak. 展开更多
关键词 low quality fly ash cement-based materials hydration products pore structure
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GMA material design and construction quality control for asphalt pavement of steel box girder: Case study of the Hong Kong–Zhuhai–Macao Bridge 被引量:2
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作者 Xiaoning Zhang 《Journal of Road Engineering》 2021年第1期63-72,共10页
To improve the quality of the Hong Kong–Zhuhai–Macao Bridge paving project,a new paving layer material,Guss-mastic asphalt(GMA),was proposed in this paper by combining the advantages of two types of cast asphalt mix... To improve the quality of the Hong Kong–Zhuhai–Macao Bridge paving project,a new paving layer material,Guss-mastic asphalt(GMA),was proposed in this paper by combining the advantages of two types of cast asphalt mixtures:mastic asphalt(MA)and Guss asphalt(GA).Based on the characteristics of GMA,to simulate its actual production process,this study developed a small-simulated cooker mixing equipment.Moreover,the flow degree,60C dynamic stability,and impact toughness were proposed to be used to evaluate the construction and ease,high temperature stability,and fatigue resistance of GMA cast asphalt mixtures,respectively.Moreover,the quality control standards for GMA paving materials by indoor tests,field trial mix GMA material performance tests,and accelerated loading tests were finalized.The study showed that the developed simulated cooker yielded consistent mixing results in the same working environment as the engineering cooker device.Increasing the coarse aggregate incorporation rate,coarsening the mastic epure(ME)gradation composition,and using a smaller oil to stone ratio can reduce the flowability of the GMA materials to varying degrees.The four-point bending fatigue life and impact toughness of the different GMA materials are correlated well.A mobility of<20 s,60C dynamic stability of 400–800 times/mm,15C impact toughness of400 N⋅mm,and cooker car mixing temperature control standard of 210C–230C form an appropriate control index system for the design and production of GMA cast asphalt mixtures.Simultaneously,accelerated loading tests verified the accuracy and reliability of the quality control index system that has been used in the GMA paving project of the Hong Kong–Zhuhai–Macao Bridge deck and has achieved good application results. 展开更多
关键词 Asphalt pavement material design GMA Steel box girder Construction quality control
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Quality Improvement of Granular Wastes-The Effective Way to Recycle Secondary Raw Building Materials
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作者 邢伟宏 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2004年第4期87-90,共4页
Granular wastes have negative effects on the environment due to contamination. On the other hand, stony components in granular wastes have a potential good perspectives for utilization in civil engineering works as se... Granular wastes have negative effects on the environment due to contamination. On the other hand, stony components in granular wastes have a potential good perspectives for utilization in civil engineering works as secondary raw building materials. To reuse such materials without environmental risks, all contaminants must be removed or reduced to an acceptable level. Therefore liberation of materials is an important step in waste treatment. For this purpose, separation and cleansing techniques are suitable. Based on the analysis of contaminants in wastes, it is discussed how to select suitable techniques. The rules for technique selection and processes for quality improvement are set up. To evaluate the environmental quality and technical quality of output products, it is necessary to check leaching behaviours and physical properties. 展开更多
关键词 granular waste secondary material contamination quality improvement separation technique
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Use of Affordable Materials to Improve Water Quality in Peri-Urban Settlements in Windhoek, Namibia
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作者 Pam Claassen Marius Hedimbi Kayeuna Basson 《Advances in Microbiology》 2015年第3期190-197,共8页
Water samples from Daan Viljoen dam, Avis dam and Goreangab dam were collected and filtered with burlap, cotton and polyester. The water samples were analyzed for the presence of total coliform, Escherichia coli, hete... Water samples from Daan Viljoen dam, Avis dam and Goreangab dam were collected and filtered with burlap, cotton and polyester. The water samples were analyzed for the presence of total coliform, Escherichia coli, heterotrophic plate count (HPC), somatic coliphage, Clostridium perfringens, turbidity and conductivity. The bacteriological analysis was carried out by membrane filtration and pour plate techniques. The water from the three dams was found to contain high levels of microorganisms which indicated that it was not safe for human consumption. Turbidity was improved after filtration. Cotton filtered out the most microorganisms (p < 0.05) in all dams compared with the other two types of cloths. 展开更多
关键词 CLOTH materialS DAMS FILTRATION Windhoek Water quality
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Evaluation of physicochemical properties as supporting information on quality control of raw materials and veterinary pharmaceutical formulations
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作者 Sara da Silva Anacleto Marcella Matos Cordeiro Borges +7 位作者 Hanna Leijoto de Oliveira Andressa Reis Vicente Eduardo Costa de Figueiredo Marcone Augusto Leal de Oliveira Barbara Juliana Pinheiro Borges Marcelo Antonio de Oliveira Warley de Souza Borges Keyller Bastos Borges 《Journal of Pharmaceutical Analysis》 SCIE CAS CSCD 2018年第3期168-175,共8页
This study aimed to show that the physicochemical proprieties obtained by Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), and scanning electronic microscopy (SEM) can be useful tools for e... This study aimed to show that the physicochemical proprieties obtained by Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), and scanning electronic microscopy (SEM) can be useful tools for evaluating the quality of active pharmaceutical ingredients (APIs) and pharmaceutical products. In addition, a simple, sensitive, and efficient method employing HPLC-DAD was developed for simulta- neous determination of lidocaine (LID), ciprofloxacin (CFX) and enrofloxacin (EFX) in raw materials and in veterinary pharmaceutical formulations. Compounds were separated using a Gemini Cm (250 mm×4.6 mm, 5μm) Phenomenex column, at a temperature of 25℃, with a mobile phase containing 10 mM of phosphoric acid (pH 3.29): acetonitrile (85.7:14.3, v/v) and a flow rate of 1.5 mL/min. Physicochemical characterization by TG, FTIR, and SEM of raw materials of LID, CFX, and EFX provided information useful for the evaluation, differentiation, and qualification of raw materials. Finally, the HPLC method was proved to be useful for evaluation of raw material and finished products, besides satisfying the need for an analytical method that allows simultaneous determination of EFX, CFX, and LID, which can also be extended to other matrices and applications. 展开更多
关键词 HPLC Physicochemical characterization quality control Veterinary pharmaceutical formulation Raw material
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Research Progress of Soil Factors Affecting the Quality of Chinese Medicinal Materials
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作者 Yuxuan TIAN Chunying ZHAO 《Medicinal Plant》 CAS 2022年第6期85-91,94,共8页
The paper summarized the effects of soil on the quality of Chinese medicinal materials from the aspects of physical,chemical and biological properties of soil,in order to provide a reference for further research on th... The paper summarized the effects of soil on the quality of Chinese medicinal materials from the aspects of physical,chemical and biological properties of soil,in order to provide a reference for further research on the internal relationship between soil factors and the quality of Chinese medicinal materials,and to provide a theoretical basis for the cultivation and quality improvement of Chinese medicinal materials. 展开更多
关键词 Chinese medicinal materials Soil factors quality
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Atmospheric Pollutants in a Commercial Region of Fortaleza, Ceará, Brazil: Integration of Health, Environment and Economy in Urban Planning to Improve Air Quality
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作者 Mônica Giovana Alves Cardoso Ratts Brenna Kessy Silva Lima +5 位作者 Gilvan Ribeiro dos Santos Fladimir de Lima Gondim Rinaldo Santos Araújo Mona Lisa Moura de Oliveira Francisco Sales Ávila Cavalcante Daniel Silveira Serra 《Journal of Geoscience and Environment Protection》 2024年第5期92-112,共21页
The accelerated growth of the vehicular fleet, the modernization of large urban centers, and the few adjustments to the road network in Fortaleza have intensified the problems of traffic and emissions of atmospheric p... The accelerated growth of the vehicular fleet, the modernization of large urban centers, and the few adjustments to the road network in Fortaleza have intensified the problems of traffic and emissions of atmospheric pollutants, highlighting the necessity for strategic urban planning initiatives to address the escalating issues of traffic and pollution. With the objective of analyzing the indices of concentrations of atmospheric pollutants and estimating how these levels can affect human health, this work consists of a study of the analysis of air quality in the intense trade region of Fortaleza. For this, the analysis zone was divided into three perimeters (Major - Medium - Minor), where each perimeter was analyzed at 7 am, 12 noon and 5 pm. Concentrations of the type of O<sub>3</sub>, particulate matter (PM<sub>2.5</sub> and PM<sub>10</sub>), CO<sub>2</sub> and HCHO were collected. Our results demonstrate that most of the analyses are within the limits of current legislation;however, at certain times and perimeters, the analyses of CO<sub>2</sub> and HCHO exceeded the established limits. In view of the above, we conclude that public policies to control air quality are necessary to reduce the damage to human health and the environment caused by pollutants. 展开更多
关键词 Air quality Urban Planning Particulate material Health Impacts
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Study on Quality Control of Concrete Raw Materials in Road and Bridge Construction
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作者 Suqin Han Xiuyong Ni Ruimin Huang 《Frontiers Research of Architecture and Engineering》 2021年第1期22-25,共4页
The main material of concrete is a construction building material composed of water and mineral mixture and cement and chemical additives in the corresponding proportion and below the standard.In the process of making... The main material of concrete is a construction building material composed of water and mineral mixture and cement and chemical additives in the corresponding proportion and below the standard.In the process of making concrete material,slurry and cement are needed to mix,then cement slurry and sand are mixed into mortar according to the corresponding proportion,and aggregate is added to mortar to form concrete building material.In the process of concrete preparation,the most important construction link is mixing,which needs to be fully stirred to make the performance of concrete meet the construction needs.In the process of concrete construction technology development,both mix ratio and production technology have become more and more mature,but there are still some problems,which have an impact on the quality of concrete[1].Therefore,this paper discusses the quality control of concrete raw materials according to the construction process of road and bridge. 展开更多
关键词 Concrete raw materials Road and bridge engineering quality control
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Risk Analysis and Quality Control of Cosmetic Raw Materials
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作者 Liu Guanfeng 《China Detergent & Cosmetics》 2021年第1期78-82,共5页
The present situation of cosmetic raw materials has been introduced,mainly including the measures of risk analysis and quality control for cosmetic raw materials.Through the inspection of cosmetic raw materials,the fo... The present situation of cosmetic raw materials has been introduced,mainly including the measures of risk analysis and quality control for cosmetic raw materials.Through the inspection of cosmetic raw materials,the formulation design and development,and the incoming management,the departments in the enterprise have worked together to achieve the risk analysis and quality control of cosmetic raw materials,to ensure the quality and safety of cosmetics. 展开更多
关键词 cosmetic raw material risk analysis quality control cosmetic quality
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The Use of Self-cleaning Materials and Study Their Impact on the Quality of the Visual Appearance of Large Industrial Cities
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作者 Sahar Mirabi 《Journal of Architectural Research and Development》 2020年第6期1-11,共11页
One of the capabilities of the architecture is to respond to growing and,in some cases,varied needs of users.However,architecture and construction industry,in comparison with other sciences,have been very slow and ina... One of the capabilities of the architecture is to respond to growing and,in some cases,varied needs of users.However,architecture and construction industry,in comparison with other sciences,have been very slow and inadequate to implement this technology despite very suitable ground for improvement.At the moment,one of the most essential discussions in this field is how to achieve qualitative understanding of construction materials.Accordingly,one of the key sections of a construction which plays a significant role in optimizing performance is shell of the building.In this article,in addition to the utilization technique of selfcleaning materials in construction industry which will result in embellishment of urban design,an attempt has also been made to present a suitable model on how to utilize these materials in order to improve the visual appearance quality of megalopolises.The technology of self-cleaning surfaces in order to increase durability and reduce costs and required time for equipment maintenance has currently become the focal point in construction industry.Now providing one answer to the question of whether will selfcleaning,purifying facades change the future of urban architecture?The main panorama of this research is to find and establish a dynamic and sustainable balance in embellishment of urban design.The necessity of research in this field as well as finding the best and most practical solution seem.To achieve all this,an analytical and descriptive research has been utilized,data has been collected by various books and national and international websites. 展开更多
关键词 Urban architecture Visual exterior of capital cities Visual quality of the façades Purifying facades Nanotechnology materials The useful life of the building
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A comparison of different methods for preserving plant molecular materials and the effect of degraded DNA on ddRAD sequencing 被引量:2
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作者 Ying Guo GuoQian Yang +2 位作者 Yunmei Chen Dezhu Li Zhenhua Guo 《Plant Diversity》 SCIE CAS CSCD 2018年第3期106-116,共11页
Obtaining high-quality plant materials for experiments is challenging for many research projects.Therefore, it is of special importance to determine the best method for preserving biological macromolecules like DNA, w... Obtaining high-quality plant materials for experiments is challenging for many research projects.Therefore, it is of special importance to determine the best method for preserving biological macromolecules like DNA, which degrade over time. Although some research has demonstrated that DNA degradation has little effect on traditional molecular markers, the effects of DNA degradation on dd RADseq, a popular reduced-representation sequencing technology, have not been adequately investigated. In this study, we first chose six woody bamboo species(Bambusoideae, Poaceae) to explore appropriate methods for preserving molecular materials with two DNA extraction approaches. Then we sequenced twenty-one bamboos and examined the effects of DNA quality on data generation using the dd RAD-seq technique(Midd RAD-seq). Finally, we reconstructed phylogenies of twenty woody bamboo species. We found that the integrity of dry-powdered DNA was preserved longer than that of TE-dissolved DNA,regardless of whether the DNA was extracted by a modified CTAB protocol or DNAsecure plant kit. The dd RAD-seq data were robust, except when DNA was severely degraded. In addition, we resolved the phylogenetic positions of the sampled Phyllostachys spp. Our results suggest that dry-powdered DNA is the most appropriate preservation method for plant molecular materials. Furthermore, a moderate level of DNA degradation has little effect on reduced representation sequencing techniques represented by dd RAD-seq. 展开更多
关键词 Molecular materials DNA extraction and preservation DNA quality ddRAD-seq BAMBOO PHYLOGENY
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Application of Factor Analysis in Sensory Evaluation of Tobacco Raw Materials 被引量:1
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作者 Zhen XIONG Lan MI +1 位作者 Yu QIN Ye QIU 《Agricultural Biotechnology》 CAS 2016年第3期13-15,共3页
[ Objective] This study aimed to analyze the main sensory quality indexes of reconstituted tobacco materials. [ Method ] The factor analysis was per- formed to analyze sensory quality of reconstituted tobacco raw mate... [ Objective] This study aimed to analyze the main sensory quality indexes of reconstituted tobacco materials. [ Method ] The factor analysis was per- formed to analyze sensory quality of reconstituted tobacco raw materials. [ Result] The results showed that the contribution rate was 87. 791% and four factors were obtained via factor analysis. The factor loading of factor 1 ( aroma quality, aroma amount, offensive odor, after-taste) was relatively large. Factor 2 was the exterior factor. Factor 3 was momentum factor. Factor 4 was the concentration factor. The comprehensive scores of samples from different regions demonstrated a descending order of Hubei, Yuxi, Chuxiong, Honghe, Dali, Kunming, Hunan, Henan, Fujian, Qujing, Baoshan, Guizhou, Zhaotong, Chongqing, Puer, Wenshan, Guang- dong, and Jiangxi. [ Conclusion] The factor analysis results provided a theoretical basis for subsequent sensory evaluation of reconstituted tobacco. 展开更多
关键词 Factor analysis Reconstituted tobacco materials Sensory quality
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Preparation of bovine liver candidate reference material
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作者 Zhang Yuan xun, Qian Yin e, Li De yi, Wang Yin song, Wang Xue peng Shanghai Institute of Nuclear Research, Chinese Academy of Sciences, Shanghai 201800, China 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 1998年第4期83-85,共3页
The bovine liver candidate reference material specially for micro analytical techniques was prepared. The preparation process including material collection, dried, pulverize, sieve, homogenization and preliminary tes... The bovine liver candidate reference material specially for micro analytical techniques was prepared. The preparation process including material collection, dried, pulverize, sieve, homogenization and preliminary test was described in detail. The more effective grinding methods were established to achieve the median particle size of 22μm. 展开更多
关键词 standard reference material bovine liver quality assurance.
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Analysis of bell materials:Tin bronzes
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作者 Jaromir Audy Katarina Audy 《China Foundry》 SCIE CAS 2008年第3期199-204,共6页
The present study was set up to examine the effect of alloying elements (including harmful elements) on metallurgical features (material properties and qualitative parameters) of tin bronzes, with particular refer... The present study was set up to examine the effect of alloying elements (including harmful elements) on metallurgical features (material properties and qualitative parameters) of tin bronzes, with particular reference to church bells from Middle Ages to Current times. A driving force of this study was to identify and demonstrate features related to the quality of church bells made in different centuries. The findings have been derived via metallographic and chemical analysis of specimens of bells from various parts of Australasia and Europe. The bell materials consisted of a mixture of the a phase and the (α+β) eutectoid essentially, in proportions determined by tin content and mould materials during casting. The samples from the 15th century to the one from the 20th century showed a progressive increase in hardness, ranging from the minimum of -280 VHM20g to a maximum of -470 VHM20g for the (α+β) eutectoid, and -160 VHM20g to -230 VHM20g for the a phase. The investigation also shows that the sound decay of the bell decreased with lowering the wt.% of tin and increasing the wt.% of lead and silver. This information is expected to provide an additional interesting knowledge into manufacturing practices and their significance in the quality of church bells over past centuries. 展开更多
关键词 tin bronzes bell material church bells MICROSTRUCTURE chemical composition material properties quality
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Evaluation of Some Radioactive Materials and Heavy Metals in Marine Environment of Alexandria Coastline, Egypt
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作者 E. R. Atta Kh. M. Zakaria 《Journal of Environmental Protection》 2014年第17期1618-1629,共12页
The present work is carried out to obtain quantitative information of some natural radioactive materials and heavy metals in water and sediment samples along the Alexandria Coastline, as a step to construct the baseli... The present work is carried out to obtain quantitative information of some natural radioactive materials and heavy metals in water and sediment samples along the Alexandria Coastline, as a step to construct the baseline map of the background radioactivity level in the Egyptian environment and also as a base data to assess the future physicochemical changes of surface coastal water and sediment in the studied area. The distribution of natural gamma emitting radionuclides such as 238U, 232Th and 40K has been established by gamma spectrometry. The results show that the area of Alexandria coast is affected by the existence of high back-ground radiation from the Rashid coast at the eastern side which has high levels of radioisotope concentrations due to black sand deposits which are dominant in this area. The absorbed dose rate (D, nGy&middot;h-1), annual effective dose equivalent, external hazard index (Hex) and representative level index (Ir) of the investigated radioactive materials were calculated. The concentration of Pb2+, Cd2+, Ni2+, Mn2+, Cu2+, Co2+, Zn2+ and Cr3+ ions has been determined using Atomic Absorption Spectroscopy. The total dissolved solids (TDS) in water samples ranged from 33,000 mg/l to 42,000 mg/l, the salinity ranged from 37.9% to 40.5% and pH ranged from 7.6 to 7.9. Some of the sediment quality guidelines are calculated and they are the metal pollution index (MPI), the contamination factor (CF), degree of contamination (Cdeg), and Pollution load index (PLI). 展开更多
关键词 Mediterranean Sea Water SEDIMENT RADIOACTIVE materials Heavy Metals SEDIMENT quality Guidelines
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Challenges of the Use of Instructional Materials in Geography Classroom in Secondary School: Nepal
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作者 Keshav Raj Dhakal 《Journal of Geographical Research》 2020年第3期36-39,共4页
Geography is an optional subject in the secondary schools in Nepal.This paper is an attempt to examine the challenges of using instructional materials in the geography classroom in community secondary schools in Kathm... Geography is an optional subject in the secondary schools in Nepal.This paper is an attempt to examine the challenges of using instructional materials in the geography classroom in community secondary schools in Kathmandu district of Bagmati Province.Geography teachers were selected by purposive sampling offering geography as an optional subject in secondary school.The semi structured interview method was used for data collection.The interviews were recorded on an audio recorder and transcribed.After collecting data,analysis of the data was made through the interpretations of the raw data by interpretative method.The results reveal that the challenges of using materials are non-availability of materials,laziness of the teachers,lack of skill and strategies,financial constraint,lack of appropriate materials in textbook,time constraint,lack of support from authority,lack of geography resource room etc.The remedies of the challenges of using materials are the organizing of training and workshop for teachers on how to use instructional materials,provision of funds by the authorities and government,regular supervision,the improvisation of the local materials and the provision of the various instructional materials which are necessary for teaching etc. 展开更多
关键词 Instructional materials Geography lesson Qualitative research quality teaching Local materials
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