Search results for: large dams
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 7123

Search results for: large dams

2473 Synthesis of Nanoparticles and Thin Film of Cu₂ZnSnS₄ by Hydrothermal Method and Its Application as Congo Red Photocatalyst

Authors: Paula Salazar, Rodrigo Henríquez, Pablo Zerega

Abstract:

The textile, food and pharmaceutical industries are expanding daily worldwide, and they are located within the most polluting industries due to the fact that wastewater is discharged into watercourses with high concentrations of dyes and traces of drugs. Many of these compounds are stable to light and biodegradation, being considered as emerging organic contaminants. Advanced oxidation processes (AOPs) emerge as an effective alternative for the removal and elimination of this type of contaminants. Heterogeneous photocatalysis has been extensively studied as it is an efficient, low-cost and durable method. As the main photocatalyst, TiO₂ has been used for the degradation of a large number of dyes and drugs. The disadvantage of TiO₂ is its absorption in the UV region of the solar spectrum. On the other hand, quaternary chalcogenides based on Cu₂SnZnX₄ (X = S, Se) are a possible alternative due to their narrow bandgap (ca. between 0.8 to 1.5 eV depending on the phase considered), low cost, an abundance of its constituent elements in the earth's crust and its low toxicity. The objective of this research was to synthesize Cu₂SnZnS₄ (CZTS) through of a low-cost hydrothermal method and evaluate it as a potential photo-catalyst in the photo-degradation process of Congo Red. The synthesis of the nanoparticle in suspension and film onto fluorine-doped tin oxide coated glass (FTO) was carried out using a mixture of: 2 mmol CuCl₂, 1 mmol ZnCl₂, 1 mmol SnCl₂ and 4 mmol CH4N₂S in a Teflon reactor at 180⁰C for 72 h. Characterization was performed through scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV VIS spectroscopy. Photo-degradation monitoring was carried out employing a UV VIS spectrophotometer. The results show that photodegradation of 55% of the dye can be obtained after 4h of exposure to polychromatic light, it should be noted that the Congo Red dye is being studied for the first time.

Keywords: CZTS, hydrothermal, photocatalysis, dye

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2472 Equipping Organic Farming in Medicinal and Aromatic Plants: Central Institute of Medicinal and Aromatic Plants' Scientific Interventions

Authors: Alok Kalra

Abstract:

Consumers and practitioners (medical herbalists, pharmacists, and aromatherapists) with strong and increased awareness about health and environment demand organically grown medicinal and aromatic plants (MAPs) to offer a valued product. As the system does not permit the use of synthetic fertilizers the use of nutrient rich organic manures is extremely important. CSIR-CIMAP has developed a complete recycling package for managing distillation and agro-waste of medicinal and aromatic plants for production of superior quality vermicompost involving microbes capable of producing high amounts of humic acid. The major benefits being faster composting period and nutrient rich vermicompost; a nutrient advantage of about 100-150% over the most commonly used organic manure (FYM). At CSIR-CIMAP, strains of microbial inoculants with multiple activities especially strains useful both as biofertilizers and biofungicide and consortia of microbes possessing diverse functional activities have been developed. CSIR-CIMAP has also initiated a program where a large number of accessions are being screened for identifying organic proficient genotypes in mints, ashwagandha, geranium and safed musli. Some of the natural plant growth promoters like calliterpenones from the plant Callicarpa macrophylla has been tested successfully for induction of rooting in stem cuttings and improving growth and yield of various crops. Some of the microbes especially the endophytes have even been identified improving the active constituents of medicinal and aromatic plants. The above said scientific interventions making organic farming a charming proposition would be discussed in details.

Keywords: organic agriculture, microbial inoculants, organic fertilizers, natural plant growth promoters

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2471 'Performance-Based' Seismic Methodology and Its Application in Seismic Design of Reinforced Concrete Structures

Authors: Jelena R. Pejović, Nina N. Serdar

Abstract:

This paper presents an analysis of the “Performance-Based” seismic design method, in order to overcome the perceived disadvantages and limitations of the existing seismic design approach based on force, in engineering practice. Bearing in mind, the specificity of the earthquake as a load and the fact that the seismic resistance of the structures solely depends on its behaviour in the nonlinear field, traditional seismic design approach based on force and linear analysis is not adequate. “Performance-Based” seismic design method is based on nonlinear analysis and can be used in everyday engineering practice. This paper presents the application of this method to eight-story high reinforced concrete building with combined structural system (reinforced concrete frame structural system in one direction and reinforced concrete ductile wall system in other direction). The nonlinear time-history analysis is performed on the spatial model of the structure using program Perform 3D, where the structure is exposed to forty real earthquake records. For considered building, large number of results were obtained. It was concluded that using this method we could, with a high degree of reliability, evaluate structural behavior under earthquake. It is obtained significant differences in the response of structures to various earthquake records. Also analysis showed that frame structural system had not performed well at the effect of earthquake records on soil like sand and gravel, while a ductile wall system had a satisfactory behavior on different types of soils.

Keywords: ductile wall, frame system, nonlinear time-history analysis, performance-based methodology, RC building

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2470 Microclimate Impacts on Solar Panel Power Generation in Midlands Area, UK

Authors: Stamatis Zoras, Boris Ceranic, Ashley Redfern

Abstract:

Green House Gas emissions from domestic properties currently account for a substantial part of the total UK’s carbon emissions and is a priority area for UK to reach zero carbon emissions. However, GHG emissions of urban complexes depend on building, road, structural developments etc surfaces that form urban microclimate. This in turn may further influence renewable energy system power generation that depend on solar or wind potential. Moreover, urban climatic conditions are also influenced by the installation of those power generation systems that may impact their own power generation efficiency. Increased air temperature is attributed to densely installed roof based solar panels that consequently impact their own production efficiency. Installation of roof based solar panels requires adequate guidance to enable housing businesses, councils and organisations to implement sufficient measures for improved power generation in relation to local urban microclimate. How microclimate is affected and how, in return, it affects solar power productivity. Derby Council & Derby Homes have been collecting solar panel power generation data for a large number of properties. The different building areas and system operation performance will be studied against microclimate conditions through time. It is envisaged that the outcomes of the study will support a working up strategy for Derby city to ensure that owned homes would be able to access information and data of solar photo voltaic PV and solar thermal panels potential on social housing, helping residents on low incomes create their own green energy to power their homes and heat their homeshot water.

Keywords: microclimate, solar power, urban climatology, urban morphology

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2469 The Relationship between Fluctuation of Biological Signal: Finger Plethysmogram in Conversation and Anthropophobic Tendency

Authors: Haruo Okabayashi

Abstract:

Human biological signals (pulse wave and brain wave, etc.) have a rhythm which shows fluctuations. This study investigates the relationship between fluctuations of biological signals which are shown by a finger plethysmogram (i.e., finger pulse wave) in conversation and anthropophobic tendency, and identifies whether the fluctuation could be an index of mental health. 32 college students participated in the experiment. The finger plethysmogram of each subject was measured in the following conversation situations: Fun memory talking/listening situation and regrettable memory talking/ listening situation for three minutes each. Lyspect 3.5 was used to collect the data of the finger plethysmogram. Since Lyspect calculates the Lyapunov spectrum, it is possible to obtain the largest Lyapunov exponent (LLE). LLE is an indicator of the fluctuation and shows the degree to which a measure is going away from close proximity to the track in a dynamical system. Before the finger plethysmogram experiment, each participant took the psychological test questionnaire “Anthropophobic Scale.” The scale measures the social phobia trend close to the consciousness of social phobia. It is revealed that there is a remarkable relationship between the fluctuation of the finger plethysmography and anthropophobic tendency scale in talking about a regrettable story in conversation: The participants (N=15) who have a low anthropophobic tendency show significantly more fluctuation of finger pulse waves than the participants (N=17) who have a high anthropophobic tendency (F (1, 31) =5.66, p<0.05). That is, the participants who have a low anthropophobic tendency make conversation flexibly using large fluctuation of biological signal; on the other hand, the participants who have a high anthropophobic tendency constrain a conversation because of small fluctuation. Therefore, fluctuation is not an error but an important drive to make better relationships with others and go towards the development of interaction. In considering mental health, the fluctuation of biological signals would be an important indicator.

Keywords: anthropophobic tendency, finger plethymogram, fluctuation of biological signal, LLE

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2468 The Status Quo, Consensus and Debates on Urbanization in Chinese Education: A General Overview of Research from the 1990s

Authors: Jingqian Xiao

Abstract:

The rapid wave of urbanization triggered by China’s economic growth over the past few decades has inevitably impacted the country’s educational landscape. Educational spaces in China shifted during the 1990s when, due to the government’s tax reforms, large numbers of rural schools were abolished or merged with urban schools, resulting in an “urbanization” of school content and values. While urbanized education is now the status quo, there is as yet no literature review, to our best knowledge, that comprehensively summarizes academic work on this phenomenon. Besides, most research on Chinese educational urbanization relies on basic policy deductions, and there is room for improvement in both the quality and quantity of empirical research on this topic. This paper, therefore, reviews relevant literature on educational urbanization in China from three interrelated factors that shape educational inequality between urban and rural China, namely the urbanization in educational space, school content, and educational values. Results find that the main discussion on Chinese educational urbanization often addresses how Chinese rural education can be improved by reforming the urbanization model to revitalize rural society. While the complete urbanization of Chinese education does not seem feasible, the rapidly changing nature of China’s development patterns and political landscape means the course of Chinese education may shift at any time. When the government does decide to fulfill its intentions to improve the countryside, many formerly dilapidated rural schools may be revived, but for the moment, both rural and urban education in China suffers from governmental neglect. In addition, the breakout of COVID-19, which led to a sudden spread of online education that reopened the gap between the educational conditions and the cultural capital of families in rural and urban areas, has also posed new challenges for China’s attempts to resolve conflicting interests between urban and rural schools and promote educational equality.

Keywords: Chinese education, educational inequality, rural and urban education, urbanization in education

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2467 University of Sciences and Technology of Oran Mohamed Boudiaf (USTO-MB)

Authors: Patricia Mikchaela D. L. Feliciano, Ciela Kadeshka A. Fuentes, Bea Trixia B. Gales, Ethel Princess A. Gepulango, Martin R. Hernandez, Elina Andrea S. Lantion, Jhoe Cynder P. Legaspi, Peter F. Quilala, Gina C. Castro

Abstract:

Propolis is a resin-like material used by bees to fill large gap holes in the beehive. It has been found to possess anti-inflammatory property, which stimulates hair growth in rats by inducing hair keratinocytes proliferation, causing water retention and preventing damage caused by heat, ultraviolet rays, and other microorganisms without abnormalities in hair follicles. The present study aimed to formulate 10% and 30% Propolis Hair Cream for use in enhancing hair properties. Raw propolis sample was tested for heavy metals using Atomic Absorption Spectroscopy; zinc and chromium were found to be present. Likewise, propolis was extracted in a percolator using 70% ethanol and concentrated under vacuum using a rotary evaporator. The propolis extract was analyzed for total flavonoid content. Compatibility of the propolis extract with excipients was evaluated using Differential Scanning Calorimetry (DSC). No significant changes in organoleptic properties, pH and viscosity of the formulated creams were noted after four weeks of storage at 2-8°C, 30°C, and 40°C. The formulated creams were found to be non-irritating based on the Modified Draize Rabbit Test. In vivo efficacy was evaluated based on thickness and tensile strength of hair grown on previously shaved rat skin. Results show that the formulated 30% propolis-based cream had greater hair enhancing properties than the 10% propolis cream, which had a comparable effect with minoxidil.

Keywords: atomic absorption spectroscopy, differential scanning calorimetry (DSC), modified draize rabbit test, propolis

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2466 Functional Connectivity Signatures of Polygenic Depression Risk in Youth

Authors: Louise Moles, Steve Riley, Sarah D. Lichenstein, Marzieh Babaeianjelodar, Robert Kohler, Annie Cheng, Corey Horien Abigail Greene, Wenjing Luo, Jonathan Ahern, Bohan Xu, Yize Zhao, Chun Chieh Fan, R. Todd Constable, Sarah W. Yip

Abstract:

Background: Risks for depression are myriad and include both genetic and brain-based factors. However, relationships between these systems are poorly understood, limiting understanding of disease etiology, particularly at the developmental level. Methods: We use a data-driven machine learning approach connectome-based predictive modeling (CPM) to identify functional connectivity signatures associated with polygenic risk scores for depression (DEP-PRS) among youth from the Adolescent Brain and Cognitive Development (ABCD) study across diverse brain states, i.e., during resting state, during affective working memory, during response inhibition, during reward processing. Results: Using 10-fold cross-validation with 100 iterations and permutation testing, CPM identified connectivity signatures of DEP-PRS across all examined brain states (rho’s=0.20-0.27, p’s<.001). Across brain states, DEP-PRS was positively predicted by increased connectivity between frontoparietal and salience networks, increased motor-sensory network connectivity, decreased salience to subcortical connectivity, and decreased subcortical to motor-sensory connectivity. Subsampling analyses demonstrated that model accuracies were robust across random subsamples of N’s=1,000, N’s=500, and N’s=250 but became unstable at N’s=100. Conclusions: These data, for the first time, identify neural networks of polygenic depression risk in a large sample of youth before the onset of significant clinical impairment. Identified networks may be considered potential treatment targets or vulnerability markers for depression risk.

Keywords: genetics, functional connectivity, pre-adolescents, depression

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2465 Numerical Studies on Thrust Vectoring Using Shock-Induced Self Impinging Secondary Jets

Authors: S. Vignesh, N. Vishnu, S. Vigneshwaran, M. Vishnu Anand, Dinesh Kumar Babu, V. R. Sanal Kumar

Abstract:

The study of the primary flow velocity and the self impinging secondary jet flow mixing is important from both the fundamental research and the application point of view. Real industrial configurations are more complex than simple shear layers present in idealized numerical thrust-vectoring models due to the presence of combustion, swirl and confinement. Predicting the flow features of self impinging secondary jets in a supersonic primary flow is complex owing to the fact that there are a large number of parameters involved. Earlier studies have been highlighted several key features of self impinging jets, but an extensive characterization in terms of jet interaction between supersonic flow and self impinging secondary sonic jets is still an active research topic. In this paper numerical studies have been carried out using a validated two-dimensional k-omega standard turbulence model for the design optimization of a thrust vector control system using shock induced self impinging secondary flow sonic jets using non-reacting flows. Efforts have been taken for examining the flow features of TVC system with various secondary jets at different divergent locations and jet impinging angles with the same inlet jet pressure and mass flow ratio. The results from the parametric studies reveal that in addition to the primary to the secondary mass flow ratio the characteristics of the self impinging secondary jets having bearing on an efficient thrust vectoring. We concluded that the self impinging secondary jet nozzles are better than single jet nozzle with the same secondary mass flow rate owing to the fact fixing of the self impinging secondary jet nozzles with proper jet angle could facilitate better thrust vectoring for any supersonic aerospace vehicle.

Keywords: fluidic thrust vectoring, rocket steering, supersonic to sonic jet interaction, TVC in aerospace vehicles

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2464 Sensitivity Enhancement of Photonic Crystal Fiber Biosensor

Authors: Mohamed Farhat O. Hameed, Yasamin K. A. Alrayk, A. A Shaalan, S. S. A. Obayya

Abstract:

The surface plasmon resonance (SPR) sensors are widely used due to its high sensitivity with molecular labels free. The commercial SPR sensors depend on the conventional prism-coupled configuration. However, this type of configuration suffers from miniaturization and integration. Therefore, the search for compact, portable and highly sensitive SPR sensors becomes mandatory.In this paper, sensitivity enhancement of a novel photonic crystal fiber biosensoris introduced and studied. The suggested design has microstructure of air holes in the core region surrounded by two large semicircular metallized channels filled with the analyte. The inner surfaces of the two channels are coated by a silver layer followed by a gold layer.The simulation results are obtained using full vectorial finite element methodwith perfect matched layer (PML) boundary conditions. The proposed design depends on bimetallic configuration to enhance the biosensor sensitivity. Additionally, the suggested biosensor can be used for multi-channel/multi-analyte sensing. In this study, the sensor geometrical parameters are studied to maximize the sensitivity for the two polarized modes. The numerical results show that high refractive index sensitivity of 4750 nm/RIU (refractive index unit) and 4300 nm/RIU can be achieved for the quasi (transverse magnetic) TM and quasi (transverse electric) TE modes of the proposed biosensor, respectively. The reportedbiosensor has advantages of integration of microfluidics setup, waveguide and metallic layers into a single structure. As a result, compact biosensor with better integration compared to conventional optical fiber SPR biosensors can be obtained.

Keywords: photonic crystal fibers, gold, silver, surface plasmon, biosensor

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2463 Tactical Urbanism and Sustainability: Tactical Experiences in the Promotion of Active Transportation

Authors: Aline Fernandes Barata, Adriana Sansão Fontes

Abstract:

The overvaluation of the use of automobile has detrimentally affected the importance of pedestrians within the city and consequently its public spaces. As a way of treating contemporary urban paradigms, Tactical Urbanism aims to recover and activate spaces through fast and easily-applied actions that demonstrate the possibility of large-scale and long-term changes in cities. Tactical interventions have represented an important practice of redefining public spaces and urban mobility. The concept of Active Transportation coheres with the idea of sustainable urban mobility, characterizing the means of transportation through human propulsion, such as walking and cycling. This paper aims to debate the potential of Tactical Urbanism in promoting Active Transportation by revealing opportunities of transformation in the urban space of contemporary cities through initiatives that promote the protection and valorization of the presence of pedestrians and cyclists in cities, and that subvert the importance of motorized vehicles. In this paper, we present the character of these actions in two different ways: when they are used as tests for permanent interventions and when they have pre-defined start and end periods. Using recent initiatives to illustrate, we aim to discuss the role of small-scale actions in promoting and incentivizing a more active, healthy, sustainable and responsive urban way of life, presenting how some of them have developed through public policies. For that, we will present some examples of tactical actions that illustrate the encouragement of Active Transportation and trials to balance the urban opportunities for pedestrians and cyclists. These include temporary closure of streets, the creation of new alternatives and more comfortable areas for walking and cycling, and the subversion of uses in public spaces where the usage of cars are predominant.

Keywords: tactical urbanism, active transportation, sustainable mobility, non-motorized means

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2462 Re-Visiting Rumi and Iqbal on Self-Enhancement for Social Responsibility

Authors: Javed Y. Uppal

Abstract:

The background of this study is the great degree of stress that the world is experiencing today, internationally among the countries, within a community among people, and even individually within one’s own self. The significance of the study is the attempt to find a solution of this stress in the philosophy of the olden times of Jalaluddin Rumi and comparatively recently of that of Allama Iqbal. The methodology adopted in this paper is firstly exploration of the perspectives of these philosophers that are being consolidated by a number of psychic and spiritual experts of today, who are being widely read but less followed. This paper further goes on presenting brief life sketches of Rumi and Iqbal. It expounds the key concepts proposed by them and the social change that was resulted in the times of the two above mentioned metaphysical philosophers. It is further amplified that with the recent advancements, in both metaphysics and the physical sciences, the gap between the two is closing down. Both Rumi and Iqbal emphasized their common essence. The old time's concepts, postulates, and philosophies are hence once again becoming valid. The findings of this paper are that the existence of human empathy, affection and mutual social attraction among humans is still valid. The positive inner belief system that dictates our thoughts and actions is vital. As a conclusion, empathy should enable us solving our problems collectively. We need to strengthen our inner communication system, to listen to the messages that come to our inner-selves. We need to get guidance and strength from them. We need to value common needs and purposes collectively to achieve results. Spiritual energy among us is to be harnessed and utilized. Connectivity is to be recognized to unify and strengthen ties among people. Mutual bonding at small and large group levels is to be employed for the survival of the disadvantaged, and sustainability of the empowering trends. With the above guidelines, hopefully, we can define a framework towards a brave and happy new humane world.

Keywords: belief system, connectivity, human empathy, inner-self, mutual bonding, spiritual energy

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2461 Early Marriage and Women's Empowerment: The Case of Chil-bride in East Hararghe Zone of Oromia National Regional State, Ethiopia

Authors: Emad Mohammed Sani

Abstract:

Women encounter exclusion and discrimination in varying degrees, particularly those who marry as minors. The detrimental custom of getting married young is still prevalent worldwide and affects millions of people. It has been less common over time, although it is still widespread in underdeveloped nations. Oromia Regional State is the region in Ethiopia with the highest proportion of child brides. This study aimed at evaluating the effects of early marriage on its survivors’ life conditions – specifically, empowerment and household decision-making – in Eastern Hararghe Zone of Oromia Region. This study employed community-based cross-sectional study design. It adopted mixed method approach – survey, in-depth interview and focus group discussion (FGD) – to collect, analyses and interpret data on early marriage and its effects on household decision-making processes. Narratives and analytical descriptions were integrated to substantiate and/or explain observed quantitative results, or generate contextual themes. According to this study, married women who were married at or after the age of eighteen participated more in household decision-making than child brides. Child brides were more likely to be victims of violence and other types of spousal abuse in their marriages. These changes are mostly caused by an individual's age at first marriage. Delaying marriage had a large positive impact on women's empowerment at the household level, and age at first marriage had a considerable negative impact. In order to advance women's welfare and emancipation, we advise more research to concentrate on the relationship between the home and the social-structural forms that appear at the individual and communal levels.

Keywords: child-bride, early marriage, women, ethiopia

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2460 An Exploration of Renewal Utilization of Under-bridge Space Based on Spatial Potential Evaluation - Taking Chongqing Municipality as an Example

Authors: Xuelian Qin

Abstract:

Urban "organic renewal" based on the development of existing resources in high-density urban areas has become the mainstream of urban development in the new era. As an important stock resource of public space in high-density urban areas, promoting its value remodeling is an effective way to alleviate the shortage of public space resources. However, due to the lack of evaluation links in the process of underpass space renewal, a large number of underpass space resources have been left idle, facing the problems of low space conversion efficiency, lack of accuracy in development decision-making, and low adaptability of functional positioning to citizens' needs. Therefore, it is of great practical significance to construct the evaluation system of under-bridge space renewal potential and explore the renewal mode. In this paper, some of the under-bridge spaces in the main urban area of Chongqing are selected as the research object. Through the questionnaire interviews with the users of the built excellent space under the bridge, three types of six levels and twenty-two potential evaluation indexes of "objective demand factor, construction feasibility factor and construction suitability factor" are selected, including six levels of land resources, infrastructure, accessibility, safety, space quality and ecological environment. The analytical hierarchy process and expert scoring method are used to determine the index weight, construct the potential evaluation system of the space under the bridge in high-density urban areas of Chongqing, and explore the direction of renewal and utilization of its suitability. To provide feasible theoretical basis and scientific decision support for the use of under bridge space in the future.

Keywords: high density urban area, potential evaluation, space under bridge, updated using

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2459 Development of Solar Energy Resources for Land along the Transportation Infrastructure: Taking the Lan-Xin Railway in the Silk Road Economic Belt as an Example

Authors: Dan Han, Yukun Zhang, Jie Zheng, Rui Zhang

Abstract:

Making full use of space along transportation infrastructure to develop renewable energy sources, especially solar energy resources, has become a research focus in relevant fields. In recent years, relevant international researches can be classified into three stages of theoretical and technical exploration, exploratory practice as well as planning implementation. Compared with traditional solar energy development mode, the development of solar energy resources in places along the transportation infrastructure has special advantages, which can also bring forth new opportunities for the development of green transportation. 'Road Integrated Photovoltaic', a development model of combining transport and new energy, has been actively studied and applied in developed countries, but it was still in its infancy in China. 'New Silk Road Economic Belt' has great advantage to carry out the 'Road Integrated Photovoltaic' because of the rich solar energy resources in its path, the shortages of renewable energy, the constraints of agricultural land and other reasons. Especially the massive amount of construction of transportation infrastructure brought by Silk Road Economic Belt, large area of developable land along the transportation line will be generated. Abundant solar energy recourses along the Silk Road will provide extremely superb practical opportunities to the land development along transportation infrastructure. We take PVsyst, GIS and Google map software for simulation of its potential by taking Lan-Xin Railway as an example, so potential electrical energy generation can be quantified and further analyzed. Research of 'New Silk Road Economic Belt' combined with 'Road Integrated Photovoltaic' is a creative development for the along transport and energy infrastructure. It not only can make full use of solar radiation and land in its path, but also bring more long-term advantages and benefits.

Keywords: land use, silk road economic belt, solar energy, transportation infrastructure

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2458 Outcome Analysis of Various Management Strategies for Ileal Perforation

Authors: Ashvamedh, Chandra Bhushan Singh, Anil Kumar Sarda

Abstract:

Introduction: Ileal perforation is a common cause for peritonitis in developing countries. Surgery is the ideal treatment as it eliminates soilage of peritoneal cavity in an effort to lessen the toxaemia and enhance the recovery of the patient. However, there is no uniformity of standardized operative procedure that is most effective for management. Material and method: The study was conducted on 66 patients of perforation peritonitis from November 2013 to February 2015 in Lok Nayak Hospital. Data of each patient were recorded on a pre-determined proforma. The methods used for repair were Primary repair, Resection anastomosis (RA) and Ileostomy. Result: Male preponderance was noticed among the patients with majority in their third decade. Of all perforations 40.9% were tubercular and 34.8% were typhoid. Amongst operated cases 27.3% underwent primary repair, RA was performed in 45.5%, Ileostomy in 27.3%patients. The average time taken for RA and ileostomy was more than primary repair. The type of repair bear no significance to size or no of perforation but was significant statistically for distance from I/C valve(P=.005) and edema of bowel wall(p=.002) when analysed for post op complications. Wound infection, dehiscence, intra-abdominal collections were complications observed bearing no significance to type of repair. Ileostomy per se has its own complications peristomal skin excoriation seen in 83.3%, electrolyte imbalance in 33.3%, duration for closure averaged 188 days (median 150 days, range 85-400 days). Conclusion: Primary closure is preferable in patients with single, small perforations. RA is advocated in patients with multiple or large perforation, perforation proximal to stricture. Ileostomy should not be considered as primary definitive procedure and reserved only for moribund patients as a lifesaving procedure. It has more morbidity and requires a second surgery for closure increasing the cost of treatment as well.

Keywords: ileal perforation, ileostomy, perforation peritonitis, typhoid perforation management

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2457 The Structure of Southern Tunisian Atlas Deformation Front: Integrated Geological and Geophysical Interpretation

Authors: D. Manai, J. Alvarez-Marron, M. Inoubli

Abstract:

The southern Tunisian Atlas is a part of the wide Cenozoic intracontinental deformation that affected North Africa as a result of convergence between African and Eurasian plates. The Southern Tunisian Atlas Front (STAF) corresponds to the chotts area that covers several hundreds of Km² and represents a 60 km wide transition between the deformed Tunisian Atlas to the North and the undeformed Saharan platform to the South. It includes three morphostructural alignments, a fold and thrust range in the North, a wide depression in the middle and a monocline to horizontal zone to the south. Four cross-sections have been constructed across the chotts area to illustrate the structure of the Southern Tunisian Atlas Front based on integrated geological and geophysical data including geological maps, petroleum wells, and seismic data. The fold and thrust zone of the northern chotts is interpreted as related to a detachment level near the Triassic-Jurassic contact. The displacement of the basal thrust seems to die out progressively under the Fejej antiform and it is responsible to the south dipping of the southern chotts range. The restoration of the cross-sections indicates that the Southern Tunisian Atlas front is a weakly deformed wide zone developed during the Cenozoic inversion with a maximum calculated shortening in the order of 1000 m. The wide structure of this STAF has been influenced by a pre-existing large thickness of upper Jurassic-Aptian sediments related to the rifting episodes associated to the evolution of Tethys in the Maghreb. During Jurassic to Aptian period, the chotts area corresponded to a highly subsiding basin.

Keywords: Southern Tunisian Atlas Front, subsident sub- basin, wide deformation, balanced cross-sections.

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2456 Intracranial Hypertension without CVST in Apla Syndrome: An Unique Association

Authors: Camelia Porey, Binaya Kumar Jaiswal

Abstract:

BACKGROUND: Antiphospholipid antibody (APLA) syndrome is an autoimmune disorder predisposing to thrombotic complications affecting CNS either by arterial vasooclusion or venous thrombosis. Cerebral venous sinus thrombosis (CVST) secondarily causes raised intracranial pressure (ICP). However, intracranial hypertension without evidence of CVST is a rare entity. Here we present two cases of elevated ICP with absence of identifiable CVST. CASE SUMMARY: Case 1, 28-year female had a 2 months history of holocranial headache followed by bilateral painless vision loss reaching lack of light perception over 20 days. CSF opening pressure was elevated. Fundoscopy showed bilateral grade 4 papilledema. MRI revealed a partially empty sella with bilateral optic nerve tortuosity. Idiopathic intracranial hypertension (IIH) was diagnosed. With acetazolamide, there was complete resolution of the clinical and radiological abnormalities. 5 months later she presented with acute onset right-sided hemiparesis. MRI was suggestive of acute left MCA infarct.MR venogram was normal. APLA came positive with high titres of Anticardiolipin and Beta 2 glycoprotein both IgG and IgM. Case 2, 23-year female, presented with headache and diplopia of 2 months duration. CSF pressure was elevated and Grade 3 papilledema was seen. MRI showed bilateral optic nerve hyperintensities with nerve head protrusion with normal MRV. APLA profile showed elevated beta 2 glycoprotein IgG and IgA. CONCLUSION: This is an important non thrombotic complication of APLA syndrome and requires further large-scale study for insight into the pathogenesis and early recognition to avoid future complications.

Keywords: APLA syndrome, idiopathic intracranial hypertension, MR venogram, papilledema

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2455 Evaluation of the Analytic for Hemodynamic Instability as a Prediction Tool for Early Identification of Patient Deterioration

Authors: Bryce Benson, Sooin Lee, Ashwin Belle

Abstract:

Unrecognized or delayed identification of patient deterioration is a key cause of in-hospitals adverse events. Clinicians rely on vital signs monitoring to recognize patient deterioration. However, due to ever increasing nursing workloads and the manual effort required, vital signs tend to be measured and recorded intermittently, and inconsistently causing large gaps during patient monitoring. Additionally, during deterioration, the body’s autonomic nervous system activates compensatory mechanisms causing the vital signs to be lagging indicators of underlying hemodynamic decline. This study analyzes the predictive efficacy of the Analytic for Hemodynamic Instability (AHI) system, an automated tool that was designed to help clinicians in early identification of deteriorating patients. The lead time analysis in this retrospective observational study assesses how far in advance AHI predicted deterioration prior to the start of an episode of hemodynamic instability (HI) becoming evident through vital signs? Results indicate that of the 362 episodes of HI in this study, 308 episodes (85%) were correctly predicted by the AHI system with a median lead time of 57 minutes and an average of 4 hours (240.5 minutes). Of the 54 episodes not predicted, AHI detected 45 of them while the episode of HI was ongoing. Of the 9 undetected, 5 were not detected by AHI due to either missing or noisy input ECG data during the episode of HI. In total, AHI was able to either predict or detect 98.9% of all episodes of HI in this study. These results suggest that AHI could provide an additional ‘pair of eyes’ on patients, continuously filling the monitoring gaps and consequently giving the patient care team the ability to be far more proactive in patient monitoring and adverse event management.

Keywords: clinical deterioration prediction, decision support system, early warning system, hemodynamic status, physiologic monitoring

Procedia PDF Downloads 187
2454 Changes in the Median Sacral Crest Associated with Sacrocaudal Fusion in the Greyhound

Authors: S. M. Ismail, H-H Yen, C. M. Murray, H. M. S. Davies

Abstract:

A recent study reported a 33% incidence of complete sacrocaudal fusion in greyhounds compared to a 3% incidence in other dogs. In the dog, the median sacral crest is formed by the fusion of sacral spinous processes. Separation of the 1st spinous process from the median crest of the sacrum in the dog has been reported as a diagnostic tool of type one lumbosacral transitional vertebra (LTV). LTV is a congenital spinal anomaly, which includes either sacralization of the caudal lumbar part or lumbarization of the most cranial sacral segment of the spine. In this study, the absence or reduction of fusion (presence of separation) between the 1st and 2ndspinous processes of the median sacral crest has been identified in association with sacrocaudal fusion in the greyhound, without any feature of LTV. In order to provide quantitative data on the absence or reduction of fusion in the median sacral crest between the 1st and 2nd sacral spinous processes, in association with sacrocaudal fusion. 204 dog sacrums free of any pathological changes (192 greyhound, 9 beagles and 3 labradors) were grouped based on the occurrence and types of fusion and the presence, absence, or reduction in the median sacral crest between the 1st and 2nd sacral spinous processes., Sacrums were described and classified as follows: F: Complete fusion (crest is present), N: Absence (fusion is absent), and R: Short crest (fusion reduced but not absent (reduction). The incidence of sacrocaudal fusion in the 204 sacrums: 57% of the sacrums were standard (3 vertebrae) and 43% were fused (4 vertebrae). Type of sacrum had a significant (p < .05) association with the absence and reduction of fusion between the 1st and 2nd sacral spinous processes of the median sacral crest. In the 108 greyhounds with standard sacrums (3 vertebrae) the percentages of F, N and R were 45% 23% and 23% respectively, while in the 84 fused (4 vertebrae) sacrums, the percentages of F, N and R were 3%, 87% and 10% respectively and these percentages were significantly different between standard (3 vertebrae) and fused (4 vertebrae) sacrums (p < .05). This indicates that absence of spinous process fusion in the median sacral crest was found in a large percentage of the greyhounds in this study and was found to be particularly prevalent in those with sacrocaudal fusion – therefore in this breed, at least, absence of sacral spinous process fusion may be unlikely to be associated with LTV.

Keywords: greyhound, median sacral crest, sacrocaudal fusion, sacral spinous process

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2453 An Unbiased Profiling of Immune Repertoire via Sequencing and Analyzing T-Cell Receptor Genes

Authors: Yi-Lin Chen, Sheng-Jou Hung, Tsunglin Liu

Abstract:

Adaptive immune system recognizes a wide range of antigens via expressing a large number of structurally distinct T cell and B cell receptor genes. The distinct receptor genes arise from complex rearrangements called V(D)J recombination, and constitute the immune repertoire. A common method of profiling immune repertoire is via amplifying recombined receptor genes using multiple primers and high-throughput sequencing. This multiplex-PCR approach is efficient; however, the resulting repertoire can be distorted because of primer bias. To eliminate primer bias, 5’ RACE is an alternative amplification approach. However, the application of RACE approach is limited by its low efficiency (i.e., the majority of data are non-regular receptor sequences, e.g., containing intronic segments) and lack of the convenient tool for analysis. We propose a computational tool that can correctly identify non-regular receptor sequences in RACE data via aligning receptor sequences against the whole gene instead of only the exon regions as done in all other tools. Using our tool, the remaining regular data allow for an accurate profiling of immune repertoire. In addition, a RACE approach is improved to yield a higher fraction of regular T-cell receptor sequences. Finally, we quantify the degree of primer bias of a multiplex-PCR approach via comparing it to the RACE approach. The results reveal significant differences in frequency of VJ combination by the two approaches. Together, we provide a new experimental and computation pipeline for an unbiased profiling of immune repertoire. As immune repertoire profiling has many applications, e.g., tracing bacterial and viral infection, detection of T cell lymphoma and minimal residual disease, monitoring cancer immunotherapy, etc., our work should benefit scientists who are interested in the applications.

Keywords: immune repertoire, T-cell receptor, 5' RACE, high-throughput sequencing, sequence alignment

Procedia PDF Downloads 194
2452 Thick Data Techniques for Identifying Abnormality in Video Frames for Wireless Capsule Endoscopy

Authors: Jinan Fiaidhi, Sabah Mohammed, Petros Zezos

Abstract:

Capsule endoscopy (CE) is an established noninvasive diagnostic modality in investigating small bowel disease. CE has a pivotal role in assessing patients with suspected bleeding or identifying evidence of active Crohn's disease in the small bowel. However, CE produces lengthy videos with at least eighty thousand frames, with a frequency rate of 2 frames per second. Gastroenterologists cannot dedicate 8 to 15 hours to reading the CE video frames to arrive at a diagnosis. This is why the issue of analyzing CE videos based on modern artificial intelligence techniques becomes a necessity. However, machine learning, including deep learning, has failed to report robust results because of the lack of large samples to train its neural nets. In this paper, we are describing a thick data approach that learns from a few anchor images. We are using sound datasets like KVASIR and CrohnIPI to filter candidate frames that include interesting anomalies in any CE video. We are identifying candidate frames based on feature extraction to provide representative measures of the anomaly, like the size of the anomaly and the color contrast compared to the image background, and later feed these features to a decision tree that can classify the candidate frames as having a condition like the Crohn's Disease. Our thick data approach reported accuracy of detecting Crohn's Disease based on the availability of ulcer areas at the candidate frames for KVASIR was 89.9% and for the CrohnIPI was 83.3%. We are continuing our research to fine-tune our approach by adding more thick data methods for enhancing diagnosis accuracy.

Keywords: thick data analytics, capsule endoscopy, Crohn’s disease, siamese neural network, decision tree

Procedia PDF Downloads 156
2451 High-Risk Gene Variant Profiling Models Ethnic Disparities in Diabetes Vulnerability

Authors: Jianhua Zhang, Weiping Chen, Guanjie Chen, Jason Flannick, Emma Fikse, Glenda Smerin, Yanqin Yang, Yulong Li, John A. Hanover, William F. Simonds

Abstract:

Ethnic disparities in many diseases are well recognized and reflect the consequences of genetic, behavior, and environmental factors. However, direct scientific evidence connecting the ethnic genetic variations and the disease disparities has been elusive, which may have led to the ethnic inequalities in large scale genetic studies. Through the genome-wide analysis of data representing 185,934 subjects, including 14,955 from our own studies of the African America Diabetes Mellitus, we discovered sets of genetic variants either unique to or conserved in all ethnicities. We further developed a quantitative gene function-based high-risk variant index (hrVI) of 20,428 genes to establish profiles that strongly correlate with the subjects' self-identified ethnicities. With respect to the ability to detect human essential and pathogenic genes, the hrVI analysis method is both comparable with and complementary to the well-known genetic analysis methods, pLI and VIRlof. Application of the ethnicity-specific hrVI analysis to the type 2 diabetes mellitus (T2DM) national repository, containing 20,791 cases and 24,440 controls, identified 114 candidate T2DM-associated genes, 8.8-fold greater than that of ethnicity-blind analysis. All the genes identified are defined as either pathogenic or likely-pathogenic in ClinVar database, with 33.3% diabetes-associated and 54.4% obesity-associated genes. These results demonstrate the utility of hrVI analysis and provide the first genetic evidence by clustering patterns of how genetic variations among ethnicities may impede the discovery of diabetes and foreseeably other disease-associated genes.

Keywords: diabetes-associated genes, ethnic health disparities, high-risk variant index, hrVI, T2DM

Procedia PDF Downloads 137
2450 Socio-Economic Setting and Implications to Climate Change Impacts in Eastern Cape Province, South Africa

Authors: Kenneth Nhundu, Leocadia Zhou, Farhad Aghdasi, Voster Muchenje

Abstract:

Climate change poses increased risks to rural communities that rely on natural resources, such as forests, cropland and rangeland, waterways, and open spaces Because of their connection to the land and the potential for climate change to impact natural resources and disrupt ecosystems and seasons, rural livelihoods and well-being are disproportionately vulnerable to climate change. Climate change has the potential to affect the environment in a number of ways that place increased stress on everyone, but disproportionately on the most vulnerable populations, including the young, the old, those with chronic illness, and the poor. The communities in the study area are predominantly rural, resource-based and are generally surrounded by public or private lands that are dominated by natural resources, including forests, rangelands, and agriculture. The livelihoods of these communities are tied to natural resources. Therefore, targeted strategies to cope will be required. This paper assessed the household socio-economic characteristics and their implications to household vulnerability to climate change impacts in the rural Eastern Cape Province, South Africa. The results indicate that the rural communities are climate-vulnerable populations as they have a large proportion of people who are less economically or physically capable of adapting to climate change. The study therefore recommends that at each level, the needs, knowledge, and voices of vulnerable populations, including indigenous peoples and resource-based communities, deserve consideration and incorporation so that climate change policy (1) ensures that all people are supported and able to act, (2) provides as robust a strategy as possible to address a rapidly changing environment, and (3) enhances equity and justice.

Keywords: climate change, vulnerable, socio-economic, livelihoods

Procedia PDF Downloads 355
2449 The Influence of Forest Management Histories on Dead and Habitat Trees in the Old Growth Forest in Northern Iran

Authors: Kiomars Sefidi

Abstract:

Dead and habitat tree such as fallen logs, snags, stumps and cracks and loos bark etc. is regarded as an important ecological component of forests on which many forest dwelling species depend, yet its relation to management history in Caspian forest has gone unreported. The aim of research was to compare the amounts of dead tree and habitat in the forests with historically different intensities of management, including: forests with the long term implication of management (PS), the short-term implication of management (NS) which were compared with semi virgin forest (GS). The number of 405 individual dead and habitat trees were recorded and measured at 109 sampling locations. ANOVA revealed volume of the dead tree in the form and decay classes significantly differ within sites and dead volume in the semi virgin forest significantly higher than managed sites. Comparing the amount of dead and habitat tree in three sites showed that dead tree volume related with management history and significantly differ in three study sites. Also, the numbers of habitat trees including cavities, Cracks and loose bark and Fork split trees significantly vary among sites. Reaching their highest in virgin site and their lowest in the site with the long term implication of management, it was concluded that forest management cause reduction of the amount of dead and habitat tree. Forest management history affect the forest's ability to generate dead tree especially in a large size, thus managing this forest according to ecological sustainable principles require a commitment to maintaining stand structure that allow, continued generation of dead tree in a full range of size.

Keywords: forest biodiversity, cracks trees, fork split trees, sustainable management, Fagus orientalis, Iran

Procedia PDF Downloads 554
2448 Geographic Information System Based Development Potentiality Assessment for Rural Villages: Case Study in Fuliang County, Jingdezhen

Authors: Sishen Wang

Abstract:

Chinese rural industry development is the major task currently during rapid urbanization. Development of potentiality assessment, evaluate the overall suitability of each village for further industrial development, could offer reference for policy makers, especially considering the limited data available in Chinese rural regions. The study focuses on 157 official villages in Fuliang County and evaluates their development potentiality by their topography, transportation condition, population, income of villagers, infrastructure and environmental conditions. Land cover changes for Fuliang county and surrounding areas of each village is also investigated for reference. The final development potentiality of each village was calculated by adding different weighted scores of different categories. Besides, inverse distance weighting (IDW) images for both final score of development potentiality and each factor were made and compared to help to understand the final result. The study found that village in the southern and northern regions have higher development potentiality than villages in the eastern and western regions, mainly because of higher income of villagers, good accessibilities and a large amount of population size. In addition, the Fuliang county was divided into five regions based on final result and policy reference for the development of each region were put forward individually. In addition, three suggestions were made for better local development potentiality: Firstly, the transportation accessibility needs to be improved in the northern regions by building more public transit system there. Secondly, the environmental conditions and infrastructure conditions in the eastern region of the county need some improvement. Thirdly, some encouragement and job opportunities should beset up in the western regions to attract labor force to move in and settle down.

Keywords: development potentiality, Fuliang GIS-Based, GIS, official village

Procedia PDF Downloads 110
2447 Temperature Dependent Current-Voltage (I-V) Characteristics of CuO-ZnO Nanorods Based Heterojunction Solar Cells

Authors: Venkatesan Annadurai, Kannan Ethirajalu, Anu Roshini Ramakrishnan

Abstract:

Copper oxide (CuO) and zinc oxide (ZnO) based coaxial (CuO-ZnO nanorods) heterojunction has been the interest of various research communities for solar cells, light emitting diodes (LEDs) and photodetectors applications. Copper oxide (CuO) is a p-type material with the band gap of 1.5 eV and it is considered to be an attractive absorber material in solar cells applications due to its high absorption coefficient and long minority carrier diffusion length. Similarly, n-type ZnO nanorods possess many attractive advantages over thin films such as, the light trapping ability and photosensitivity owing to the presence of oxygen related hole-traps at the surface. Moreover, the abundant availability, non-toxicity, and inexpensiveness of these materials make them suitable for potentially cheap, large area, and stable photovoltaic applications. However, the efficiency of the CuO-ZnO nanorods heterojunction based devices is greatly affected by interface defects which generally lead to the poor performance. In spite of having much potential, not much work has been carried out to understand the interface quality and transport mechanism involved across the CuO-ZnO nanorods heterojunction. Therefore, a detailed investigation of CuO-ZnO heterojunction is needed to understand the interface which affects its photovoltaic performance. Herein, we have fabricated the CuO-ZnO nanorods based heterojunction by simple hydrothermal and electrodeposition technique and investigated its interface quality by carrying out temperature (300 –10 K) dependent current-voltage (I-V) measurements under dark and illumination of visible light. Activation energies extracted from the temperature dependent I-V characteristics reveals that recombination and tunneling mechanism across the interfacial barrier plays a significant role in the current flow.

Keywords: heterojunction, electrical transport, nanorods, solar cells

Procedia PDF Downloads 224
2446 Electrospun Membrane doped with Gold Nanorods for Surface-Enhanced Raman Sepctroscopy

Authors: Ziwei Wang, Andrea Lucotti, Luigi Brambilla, Matteo Tommasini, Chiara Bertarelli

Abstract:

Surface-enhanced Raman Spectroscopy (SERS) is a highly sensitive detection that provides abundant information on low concentration analytes from various researching areas. Based on localized surface plasmon resonance, metal nanostructures including gold, silver and copper have been investigated as SERS substrate during recent decades. There has been increasing more attention of exploring good performance, homogenous, repeatable SERS substrates. Here, we show that electrospinning, which is an inexpensive technique to fabricate large-scale, self-standing and repeatable membranes, can be effectively used for producing SERS substrates. Nanoparticles and nanorods are added to the feed electrospinning solution to collect functionalized polymer fibrous mats. We report stable electrospun membranes as SERS substrate using gold nanorods (AuNRs) and poly(vinyl alcohol). Particularly, a post-processing crosslinking step using glutaraldehyde under acetone environment was carried out to the electrospun membrane. It allows for using the membrane in any liquid environment, including water, which is of interest both for sensing of contaminant in wastewater, as well as for biosensing. This crosslinked AuNRs/PVA membrane has demonstrated excellent performance as SERS substrate for low concentration 10-6 M Rhodamine 6G (Rh6G) aqueous solution. This post-processing for fabricating SERS substrate is the first time reported and proved through Raman imaging of excellent stability and outstanding performance. Finally, SERS tests have been applied to several analytes, and the application of AuNRs/PVA membrane is broadened by removing the detected analyte by rinsing. Therefore, this crosslinked AuNRs/PVA membrane is re-usable.

Keywords: SERS spectroscopy, electrospinning, crosslinking, composite materials

Procedia PDF Downloads 141
2445 Sustainable Use of Agricultural Waste to Enhance Food Security and Conserve the Environment

Authors: M. M. Tawfik, Ezzat M. Abd El Lateef, B. B. Mekki, Amany A. Bahr, Magda H. Mohamed, Gehan S. Bakhoom

Abstract:

The rapid increase in the world’s population coupled by decrease the arable land per capita has resulted into an increased demand for food which has in turn led to the production of large amounts of agricultural wastes, both at the farmer, municipality and city levels. Agricultural wastes can be a valuable resource for improving food security. Unfortunately, agricultural wastes are likely to cause pollution to the environment or even harm to human health. This calls for increased public awareness on the benefits and potential hazards of agricultural wastes, especially in developing countries. Agricultural wastes (residual stalks, straw, leaves, roots, husks, shells etcetera) and animal waste (manures) are widely available, renewable and virtually free, hence they can be an important resource. They can be converted into heat, steam, charcoal, methanol, ethanol, bio diesel as well as raw materials (animal feed, composting, energy and biogas construction etcetera). agricultural wastes are likely to cause pollution to the environment or even harm to human health, if it is not used in a sustainable manner. Organic wastes could be considered an important source of biofertilizer for enhancing food security in the small holder farming communities that would not afford use of expensive inorganic fertilizers. Moreover, these organic wastes contain high levels of nitrogen, phosphorus, potassium, and organic matter important for improving nutrient status of soils in urban agriculture. Organic compost leading to improved crop yields and its nutritional values as compared with inorganic fertilization. This paper briefly reviews how agricultural wastes can be used to enhance food security and conserve the environment.

Keywords: agricultural waste, organic compost, environment, valuable resources

Procedia PDF Downloads 520
2444 All-Optical Gamma-Rays and Positrons Source by Ultra-Intense Laser Irradiating an Al Cone

Authors: T. P. Yu, J. J. Liu, X. L. Zhu, Y. Yin, W. Q. Wang, J. M. Ouyang, F. Q. Shao

Abstract:

A strong electromagnetic field with E>1015V/m can be supplied by an intense laser such as ELI and HiPER in the near future. Exposing in such a strong laser field, laser-matter interaction enters into the near quantum electrodynamics (QED) regime and highly non-linear physics may occur during the laser-matter interaction. Recently, the multi-photon Breit-Wheeler (BW) process attracts increasing attention because it is capable to produce abundant positrons and it enhances the positron generation efficiency significantly. Here, we propose an all-optical scheme for bright gamma rays and dense positrons generation by irradiating a 1022 W/cm2 laser pulse onto an Al cone filled with near-critical-density plasmas. Two-dimensional (2D) QED particle-in-cell (PIC) simulations show that, the radiation damping force becomes large enough to compensate for the Lorentz force in the cone, causing radiation-reaction trapping of a dense electron bunch in the laser field. The trapped electrons oscillate in the laser electric field and emits high-energy gamma photons in two ways: (1) nonlinear Compton scattering due to the oscillation of electrons in the laser fields, and (2) Compton backwardscattering resulting from the bunch colliding with the reflected laser by the cone tip. The multi-photon Breit-Wheeler process is thus initiated and abundant electron-positron pairs are generated with a positron density ~1027m-3. The scheme is finally demonstrated by full 3D PIC simulations, which indicate the positron flux is up to 109. This compact gamma ray and positron source may have promising applications in future.

Keywords: BW process, electron-positron pairs, gamma rays emission, ultra-intense laser

Procedia PDF Downloads 260