Search results for: cell viability
1160 Genome-Wide Isoform Specific KDM5A/JARID1A/RBP2 Location Analysis Reveals Contribution of Chromatin-Interacting PHD Domain in Protein Recruitment to Binding Sites
Authors: Abul B. M. M. K. Islam, Nuria Lopez-Bigas, Elizaveta V. Benevolenskaya
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RBP2 has shown to be important for cell differentiation control through epigenetic mechanism. The main aim of the present study is genome-wide location analysis of human RBP2 isoforms that differ in a histone-binding domain by ChIPseq. It is conceivable that the larger isoform (LI) of RBP2, which contains a specific H3K4me3 interacting domain, differs from the smaller isoform (SI) in genomic location, may account for the observed diversity in RBP2 function. To distinguish the two RBP2 isoforms, we used the fact that the SI lacks the C-terminal PHD domain and hence used the antibodies detecting both RBP2 isoforms (AI) through a common central domain, and the antibodies detecting only LI but not SI, through a C-terminal PHD domain. Overall our analysis suggests that RBP2 occupies about 77 nucleotides and binds GC rich motifs of active genes, does not bind to centromere, telomere, or enhancer regions, and binding sites are conserved compare to random. A striking difference between the only-SI and only-LI is that a large number of only-SI peaks are located in CpG islands and close to TSS compared to only-LI peaks. Enrichment analysis of the related genes indicates that several oncogenic pathways and metabolic pathways/processes are significantly enriched among only-SI/AI targets, but not LI/only-LI peak’s targets.Keywords: bioinformatics, cancer, ChIP-seq, KDM5A
Procedia PDF Downloads 3071159 Crystallization Fouling from Potable Water in Heat Exchangers and Evaporators
Authors: Amthal Al-Gailani, Olujide Sanni, Thibaut Charpentier, Anne Neville
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Formation of inorganic scale on heat transfer surfaces is a serious problem encountered in industrial, commercial, and domestic heat exchangers and systems. Several industries use potable/groundwater sources such as rivers, lakes, and oceans to use water as a working fluid in heat exchangers and steamers. As potable/surface water contains diverse salt ionic species, the scaling kinetics and deposit morphology are expected to be different from those found in artificially hardened solutions. In this work, scale formation on the heat transfer surfaces from potable water has been studied using a once-through open flow cell under atmospheric pressure. The surface scaling mechanism and deposit morphology are investigated at high surface temperature. Thus the water evaporation process has to be considered. The effect of surface temperature, flow rate, and inhibitor deployment on the thermal resistance and morphology of the scale have been investigated. The study findings show how an increase in surface temperature enhances the crystallization reaction kinetics on the surface. There is an increase in the amount of scale and the resistance to heat transfer. The fluid flow rate also increases the fouling resistance and the thickness of the scale layer.Keywords: fouling, heat exchanger, thermal resistance, crystallization, potable water
Procedia PDF Downloads 1451158 Geospatial Modeling Framework for Enhancing Urban Roadway Intersection Safety
Authors: Neeti Nayak, Khalid Duri
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Despite the many advances made in transportation planning, the number of injuries and fatalities in the United States which involve motorized vehicles near intersections remain largely unchanged year over year. Data from the National Highway Traffic Safety Administration for 2018 indicates accidents involving motorized vehicles at traffic intersections accounted for 8,245 deaths and 914,811 injuries. Furthermore, collisions involving pedal cyclists killed 861 people (38% at intersections) and injured 46,295 (68% at intersections), while accidents involving pedestrians claimed 6,247 lives (25% at intersections) and injured 71,887 (56% at intersections)- the highest tallies registered in nearly 20 years. Some of the causes attributed to the rising number of accidents relate to increasing populations and the associated changes in land and traffic usage patterns, insufficient visibility conditions, and inadequate applications of traffic controls. Intersections that were initially designed with a particular land use pattern in mind may be rendered obsolete by subsequent developments. Many accidents involving pedestrians are accounted for by locations which should have been designed for safe crosswalks. Conventional solutions for evaluating intersection safety often require costly deployment of engineering surveys and analysis, which limit the capacity of resource-constrained administrations to satisfy their community’s needs for safe roadways adequately, effectively relegating mitigation efforts for high-risk areas to post-incident responses. This paper demonstrates how geospatial technology can identify high-risk locations and evaluate the viability of specific intersection management techniques. GIS is used to simulate relevant real-world conditions- the presence of traffic controls, zoning records, locations of interest for human activity, design speed of roadways, topographic details and immovable structures. The proposed methodology provides a low-cost mechanism for empowering urban planners to reduce the risks of accidents using 2-dimensional data representing multi-modal street networks, parcels, crosswalks and demographic information alongside 3-dimensional models of buildings, elevation, slope and aspect surfaces to evaluate visibility and lighting conditions and estimate probabilities for jaywalking and risks posed by blind or uncontrolled intersections. The proposed tools were developed using sample areas of Southern California, but the model will scale to other cities which conform to similar transportation standards given the availability of relevant GIS data.Keywords: crosswalks, cyclist safety, geotechnology, GIS, intersection safety, pedestrian safety, roadway safety, transportation planning, urban design
Procedia PDF Downloads 1091157 HyDUS Project; Seeking a Wonder Material for Hydrogen Storage
Authors: Monica Jong, Antonios Banos, Tom Scott, Chris Webster, David Fletcher
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Hydrogen, as a clean alternative to methane, is relatively easy to make, either from water using electrolysis or from methane using steam reformation. However, hydrogen is much trickier to store than methane, and without effective storage, it simply won’t pass muster as a suitable methane substitute. Physical storage of hydrogen is quite inefficient. Storing hydrogen as a compressed gas at pressures up to 900 times atmospheric is volumetrically inefficient and carries safety implications, whilst storing it as a liquid requires costly and constant cryogenic cooling to minus 253°C. This is where DU steps in as a possible solution. Across the periodic table, there are many different metallic elements that will react with hydrogen to form a chemical compound known as a hydride (or metal hydride). From a chemical perspective, the ‘king’ of the hydride forming metals is palladium because it offers the highest hydrogen storage volumetric capacity. However, this material is simply too expensive and scarce to be used in a scaled-up bulk hydrogen storage solution. Depleted Uranium is the second most volumetrically efficient hydride-forming metal after palladium. The UK has accrued a significant amount of DU because of manufacturing nuclear fuel for many decades, and that is currently without real commercial use. Uranium trihydride (UH3) contains three hydrogen atoms for every uranium atom and can chemically store hydrogen at ambient pressure and temperature at more than twice the density of pure liquid hydrogen for the same volume. To release the hydrogen from the hydride, all you do is heat it up. At temperatures above 250°C, the hydride starts to thermally decompose, releasing hydrogen as a gas and leaving the Uranium as a metal again. The reversible nature of this reaction allows the hydride to be formed and unformed again and again, enabling its use as a high-density hydrogen storage material which is already available in large quantities because of its stockpiling as a ‘waste’ by-product. Whilst the tritium storage credentials of Uranium have been rigorously proven at the laboratory scale and at the fusion demonstrator JET for over 30 years, there is a need to prove the concept for depleted uranium hydrogen storage (HyDUS) at scales towards that which is needed to flexibly supply our national power grid with energy. This is exactly the purpose of the HyDUS project, a collaborative venture involving EDF as the interested energy vendor, Urenco as the owner of the waste DU, and the University of Bristol with the UKAEA as the architects of the technology. The team will embark on building and proving the world’s first pilot scale demonstrator of bulk chemical hydrogen storage using depleted Uranium. Within 24 months, the team will attempt to prove both the technical and commercial viability of this technology as a longer duration energy storage solution for the UK. The HyDUS project seeks to enable a true by-product to wonder material story for depleted Uranium, demonstrating that we can think sustainably about unlocking the potential value trapped inside nuclear waste materials.Keywords: hydrogen, long duration storage, storage, depleted uranium, HyDUS
Procedia PDF Downloads 1571156 Recent Trend in Gluten-Free Bakery Products
Authors: Madhuresh Dwivedi, Navneet Singh Deora, H. N. Mishra
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In the context of bakery products, the gluten component of wheat has a crucial role in stabilizing the gas-cell and crumb structures, appearance, mouth feel and maintaining the rheological properties, thus the acceptability of these products. However, because of coeliac disease, some individuals cannot tolerate the protein gliadin present in the gluten fraction of wheat flour. Also termed as gluten-sensitive enteropathy, it is a common chronicle disorder in populations throughout the world with average prevalence of 0.37%. The safest way for celiac sufferers is to stay away from gluten-containing foods such as wheat, rye, barley as well as durum wheat, spelt wheat, and triticale. Thus, in view of the current increasing incidence of gluten intolerant sufferers (due to improved diagnostic procedures), the development of gluten-free cereal-based bakery products suitable for celiac patients represents a challenging and serious task, but also very demanding call for food technologists as well as for the bakers. The use of alternative cereal starches (like rice, soy, maize, potato and so on), gums, hydrocolloids, dietary fibres, alternative protein sources, prebiotics and combinations of them represent the most widespread approach used as replacement to mimic gluten in the manufacture of industrial processable gluten-free bakery products due to their structure-building and water binding properties.Keywords: gluten-free, coeliac disease, alternative flour, hydrocolloid, crumb structure
Procedia PDF Downloads 2771155 Altered TP53 Mutations in de Novo Acute Myeloid Leukemia Patients in Iran
Authors: Naser Shagerdi Esmaeli, Mohsen Hamidpour, Parisa Hasankhani Tehrani
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Background: The TP53 mutation is frequently detected in acute myeloid leukemia (AML) patients with complex karyotype (CK), but the stability of this mutation during the clinical course remains unclear. Material and Methods: In this study, TP53 mutations were identified in 7% of 500 patients with de novo AML and 58.8% of patients with CK in Tabriz, Iran. TP53 mutations were closely associated with older age, lower white blood cell (WBC) and platelet counts, FAB M6 subtype, unfavorable-risk cytogenetics, and CK, but negatively associated with NPM1 mutation, FLT3/ITD and DNMT3A mutation. Result: Multivariate analysis demonstrated that TP53 mutation was an independent poor prognostic factor for overall survival and disease-free survival among the total cohort and the subgroup of patients with CK. A scoring system incorporating TP53 mutation and nine other prognostic factors, including age, WBC counts, cytogenetics, and gene mutations, into survival analysis proved to be very useful to stratify AML patients. Sequential study of 420 samples showed that TP53 mutations were stable during AML evolution, whereas the mutation was acquired only in 1 of the 126 TP53 wild-type patients when therapy-related AML originated from different clone emerged. Conclusion: In conclusion, TP53 mutations are associated with distinct clinic-biological features and poor prognosis in de novo AML patients and are rather stable during disease progression.Keywords: acute myloblastic leukemia, TP53, FLT3/ITD, Iran
Procedia PDF Downloads 1071154 Nursery Treatments May Improve Restoration Outcomes by Reducing Seedling Transplant Shock
Authors: Douglas E. Mainhart, Alejandro Fierro-Cabo, Bradley Christoffersen, Charlotte Reemts
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Semi-arid ecosystems across the globe have faced land conversion for agriculture and resource extraction activities, posing a threat to the important ecosystem services they provide. Revegetation-centered restoration efforts in these regions face low success rates due to limited soil water availability and high temperatures leading to elevated seedling mortality after planting. Typical methods to alleviate these stresses require costly post-planting interventions aimed at improving soil moisture status. We set out to evaluate the efficacy of applying in-nursery treatments to address transplant shock. Four native Tamaulipan thornscrub species were compared. Three treatments were applied: elevated CO2, drought hardening (four-week exposure each), and antitranspirant foliar spray (the day prior to planting). Our goal was to answer two primary questions: (1) Do treatments improve survival and growth of seedlings in the early period post-planting? (2) If so, what underlying physiological changes are associated with this improved performance? To this end, we measured leaf gas exchange (stomatal conductance, light saturated photosynthetic rate, water use efficiency), leaf morphology (specific leaf area), and osmolality before and upon the conclusion of treatments. A subset of seedlings from all treatments have been planted, which will be monitored in coming months for in-field survival and growth.First month field survival for all treatment groups were high due to ample rainfall following planting (>85%). Growth data was unreliable due to high herbivory (68% of all sampled plants). While elevated CO2 had infrequent or no detectable influence on all aspects of leaf gas exchange, drought hardening reduced stomatal conductance in three of the four species measured without negatively impacting photosynthesis. Both CO2 and drought hardening elevated leaf osmolality in two species. Antitranspirant application significantly reduced conductance in all species for up to four days and reduced photosynthesis in two species. Antitranspirants also increased the variability of water use efficiency compared to controls. Collectively, these results suggest that antitranspirants and drought hardening are viable treatments for reducing short-term water loss during the transplant shock period. Elevated CO2, while not effective at reducing water loss, may be useful for promoting more favorable water status via osmotic adjustment. These practices could improve restoration outcomes in Tamaulipan thornscrub and other semi-arid systems. Further research should focus on evaluating combinations of these treatments and their species-specific viability.Keywords: conservation, drought conditioning, semi-arid restoration, plant physiology
Procedia PDF Downloads 861153 The impact of Breast Cancer Polymorphism on Breast Cancer
Authors: Roudabeh Vakil Monfared, Farhad Mashayekhi
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Breast cancer is the most common malignancy type among women with about 1 million new cases each year. The immune system plays an important role in the breast cancer development. OX40L (also known as TNFSF4), a membrane protein, which is a member of the tumor necrosis factor super family binds to its receptor OX40 and this co-stimulation has a crucial role in T-cell proliferation, survival and cytokine release. Due to the importance of the T-cells in anti-tumor activities of OX40L we studied the association of rs3850641 (T→C) polymorphism of OX40L gene with breast cancer. The study included 123 women with breast cancer and 126 healthy volunteers with no signs of cancer. Genomic DNA was extracted from blood leucocytes. Genotype and allele frequencies were determined in patients and control cases with the method of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and the analysis was performed by Med Calc. The prevalence of genotype frequencies of TT, CT and CC were 60.9%, 30.08% and 8.9 % in patients with breast cancer and 74.6 %, 18.25 % and 7.14 % in healthy volunteers while the T and C allelic frequency was 76.01% and 23.98 % in patients and 83.73% and 16.26% in healthy controls. Respectively Statistical analysis has shown no significant difference from the comparison of either genotype (P=0.06). According to these results, the rs3850641 SNP has no association with the susceptibility of breast cancer in a population in northern Iran. However, further studies in larger populations including other genetic and environmental factors are required to achieve conclusion.Keywords: OX40L, gene, polymorphism, breast cancer
Procedia PDF Downloads 5351152 Application of Electrochemically Prepared PPy/MWCNT:MnO2 Nano-Composite Film in Microbial Fuel Cells for Sustainable Power Generation
Authors: Rajeev jain, D. C. Tiwari, Praveena Mishra
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Nano-composite of polypyrrole/multiwalled carbon nanotubes:mangenese oxide (PPy/MWCNT:MnO2) was electrochemically deposited on the surface of carbon cloth (CC). The nano-composite was structurally characterized by FTIR, SEM, TEM and UV-Vis studies. Nano-composite was also characterized by cyclic voltammetry (CV), current voltage measurements (I-V) and the optical band gaps of film were evaluated from UV-Vis absorption studies. The PPy/MWCNT:MnO2 nano-composite was used as anode in microbial fuel cell (MFC) for sewage waste water treatment, power and coulombic efficiency measurement. The prepared electrode showed good electrical conductivity (0.1185 S m-1). This was also supported by band gap measurements (direct 0.8 eV, indirect 1.3 eV). The obtained maximum power density was 1125.4 mW m-2, highest chemical oxygen demand (COD) removal efficiency was 93% and the maximum coulombic efficiency was 59%. For the first time PPy/MWCNT:MnO2 nano-composite for MFC prepared from nano-composite electrode having the potential for the use in MFC with good stability and better adhesion of microbes is being reported. The SEM images confirm the growth and development of microbe’s colony.Keywords: carbon cloth, electro-polymerization, functionalization, microbial fuel cells, multi walled carbon nanotubes, polypyrrole
Procedia PDF Downloads 2711151 Application of Bioreactors in Regenerative Dentistry: Literature Review
Authors: Neeraj Malhotra
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Background: Bioreactors in tissue engineering are used as devices that apply mechanical means to influence biological processes. They are commonly employed for stem cell culturing, growth and expansion as well as in 3D tissue culture. Contemporarily there use is well established and is tested extensively in the medical sciences, for tissue-regeneration and tissue engineering of organs like bone, cartilage, blood vessels, skin grafts, cardiac muscle etc. Methodology: Literature search, both electronic and hand search, was done using the following MeSH and keywords: bioreactors, bioreactors and dentistry, bioreactors & dental tissue engineering, bioreactors and regenerative dentistry. Articles published only in English language were included for review. Results: Bioreactors like, spinner flask-, rotating wall-, flow perfusion-, and micro-bioreactors and in-vivo bioreactor have been employed and tested for the regeneration of dental and like-tissues. These include gingival tissue, periodontal ligament, alveolar bone, mucosa, cementum and blood vessels. Based on their working dynamics they can be customized in future for regeneration of pulp tissue and whole tooth regeneration. Apart from this, they have been successfully used in testing the clinical efficacy and biological safety of dental biomaterials. Conclusion: Bioreactors have potential use in testing dental biomaterials and tissue engineering approaches aimed at regenerative dentistry.Keywords: bioreactors, biological process, mechanical stimulation, regenerative dentistry, stem cells
Procedia PDF Downloads 2091150 Design and Fabrication of a Programmable Stiffness-Sensitive Gripper for Object Handling
Authors: Mehdi Modabberifar, Sanaz Jabary, Mojtaba Ghodsi
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Stiffness sensing is an important issue in medical diagnostic, robotics surgery, safe handling, and safe grasping of objects in production lines. Detecting and obtaining the characteristics in dwelling lumps embedded in a soft tissue and safe removing and handling of detected lumps is needed in surgery. Also in industry, grasping and handling an object without damaging in a place where it is not possible to access a human operator is very important. In this paper, a method for object handling is presented. It is based on the use of an intelligent gripper to detect the object stiffness and then setting a programmable force for grasping the object to move it. The main components of this system includes sensors (sensors for measuring force and displacement), electrical (electrical and electronic circuits, tactile data processing and force control system), mechanical (gripper mechanism and driving system for the gripper) and the display unit. The system uses a rotary potentiometer for measuring gripper displacement. A microcontroller using the feedback received by the load cell, mounted on the finger of the gripper, calculates the amount of stiffness, and then commands the gripper motor to apply a certain force on the object. Results of Experiments on some samples with different stiffness show that the gripper works successfully. The gripper can be used in haptic interfaces or robotic systems used for object handling.Keywords: gripper, haptic, stiffness, robotic
Procedia PDF Downloads 3581149 Inhibitory Impacts of Fulvic Acid-Coated Iron Oxide Nano Particles on the Amyloid Fibril Aggregations
Authors: Dalia Jomehpour, Sara Sheikhlary, Esmaeil Heydari, Mohammad Hossien Majles Ara
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In this study, we report fulvic acid-coated iron oxide nanoparticles of 10.7 ± 2.7 nm size, which serve to inhibit amyloid fibrillation formation. Although the effect of fulvic acid on tau fibrils was investigated, to our best knowledge, its inhibitory impacts on amyloid aggregation formation have been assessed neither in-vitro nor in-vivo. On the other hand, iron oxide nanoparticles exhibit anti-amyloid activity on their own. This study investigates the inhibitory effect of fulvic acid coated iron oxide nanoparticles on amyloid aggregations formed from the commonly used in-vitro model, lysozyme from chicken egg white. FESEM, XRD, and FTIR characterization confirmed that fulvic acid was coated onto the surface of the nanoparticles. The inhibitory effects of the fulvic acid coated iron oxide nanoparticles were verified by Thioflavin T assay, circular dichroism (CD), and FESEM analysis. Furthermore, the toxicity of the nanoparticles on the neuroblastoma SH-SY5Y human cell line was assessed through an MTT assay. Our results indicate that fulvic acid coated iron oxide nanoparticles can efficiently inhibit the formation of amyloid aggregations while exhibiting negligible in-vitro toxicity; thus, they can be used as anti-amyloid agents in the development of the potential drug for neurodegenerative diseases.Keywords: Alzheimer’s disease, fulvic acid coated iron oxide nanoparticles, fulvic acid, amyloid inhibitor, polyphenols
Procedia PDF Downloads 1121148 Sustainability in Space: Material Efficiency in Space Missions
Authors: Hamda M. Al-Ali
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From addressing fundamental questions about the history of the solar system to exploring other planets for any signs of life have always been the core of human space exploration. This triggered humans to explore whether other planets such as Mars could support human life on them. Therefore, many planned space missions to other planets have been designed and conducted to examine the feasibility of human survival on them. However, space missions are expensive and consume a large number of various resources to be successful. To overcome these problems, material efficiency shall be maximized through the use of reusable launch vehicles (RLV) rather than disposable and expendable ones. Material efficiency is defined as a way to achieve service requirements using fewer materials to reduce CO2 emissions from industrial processes. Materials such as aluminum-lithium alloys, steel, Kevlar, and reinforced carbon-carbon composites used in the manufacturing of spacecrafts could be reused in closed-loop cycles directly or by adding a protective coat. Material efficiency is a fundamental principle of a circular economy. The circular economy aims to cutback waste and reduce pollution through maximizing material efficiency so that businesses can succeed and endure. Five strategies have been proposed to improve material efficiency in the space industry, which includes waste minimization, introduce Key Performance Indicators (KPIs) to measure material efficiency, and introduce policies and legislations to improve material efficiency in the space sector. Another strategy to boost material efficiency is through maximizing resource and energy efficiency through material reusability. Furthermore, the environmental effects associated with the rapid growth in the number of space missions include black carbon emissions that lead to climate change. The levels of emissions must be tracked and tackled to ensure the safe utilization of space in the future. The aim of this research paper is to examine and suggest effective methods used to improve material efficiency in space missions so that space and Earth become more environmentally and economically sustainable. The objectives used to fulfill this aim are to identify the materials used in space missions that are suitable to be reused in closed-loop cycles considering material efficiency indicators and circular economy concepts. An explanation of how spacecraft materials could be re-used as well as propose strategies to maximize material efficiency in order to make RLVs possible so that access to space becomes affordable and reliable is provided. Also, the economic viability of the RLVs is examined to show the extent to which the use of RLVs has on the reduction of space mission costs. The environmental and economic implications of the increase in the number of space missions as a result of the use of RLVs are also discussed. These research questions are studied through detailed critical analysis of the literature, such as published reports, books, scientific articles, and journals. A combination of keywords such as material efficiency, circular economy, RLVs, and spacecraft materials were used to search for appropriate literature.Keywords: access to space, circular economy, material efficiency, reusable launch vehicles, spacecraft materials
Procedia PDF Downloads 1131147 Genome-Wide Identification of Genes Resistance to Nitric Oxide in Vibrio parahaemolyticus
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Food poison caused by consumption of contaminated food, especially seafood, is one of most serious public health threats worldwide. Vibrio parahaemolyticus is emerging bacterial pathogen and the leading cause of human gastroenteritis associated with food poison, especially in the southern coastal region of China. To successfully cause disease in host, bacterial pathogens need to overcome the host-derived stresses encountered during infection. One of the toxic chemical species elaborated by the host is nitric oxide (NO). NO is generated by acidified nitrite in the stomach and by enzymes of the inducible NO synthase (iNOS) in the host cell, and is toxic to bacteria. Bacterial pathogens have evolved some mechanisms to battle with this toxic stress. Such mechanisms include genes to sense NO produced from immune system and activate others to detoxify NO toxicity, and genes to repair the damage caused by toxic reactive nitrogen species (RNS) generated during NO toxic stress. However, little is known about the NO resistance in V. parahaemolyticus. In this study, a transposon coupled with next generation sequencing (Tn-seq) technology will be utilized to identify genes for NO resistance in V. parahaemolyticus. Our strategy will include construction the saturating transposon insertion library, transposon library challenging with NO, next generation sequencing (NGS), bioinformatics analysis and verification of the identified genes in vitro and in vivo.Keywords: vibrio parahaemolyticus, nitric oxide, tn-seq, virulence
Procedia PDF Downloads 2641146 Sound Instance: Art, Perception and Composition through Soundscapes
Authors: Ricardo Mestre
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The soundscape stands out as an agglomeration of sounds available in the world, associated with different contexts and origins, being a theme studied by various areas of knowledge, seeking to guide their benefits and their consequences, contributing to the welfare of society and other ecosystems. Murray Schafer, the author who originally developed this concept, highlights the need for a greater recognition of sound reality, through the selection and differentiation of sounds, contributing to a tuning of the world and to the balance and well-being of humanity. According to some authors sound environment, produced and created in various ways, provides various sources of information, contributing to the orientation of the human being, alerting and manipulating him during his daily journey, like small notifications received on a cell phone or other device with these features. In this way, it becomes possible to give sound its due importance in relation to the processes of individual representation, in manners of social, professional and emotional life. Ensuring an individual representation means providing the human being with new tools for the long process of reflection by recognizing his environment, the sounds that represent him, and his perspective on his respective function in it. In order to provide more information about the importance of the sound environment inherent to the individual reality, one introduces the term sound instance, in order to refer to the whole sound field existing in the individual's life, which is divided into four distinct subfields, but essential to the process of individual representation, called sound matrix, sound cycles, sound traces and sound interference.Keywords: sound instance, soundscape, sound art, perception, composition
Procedia PDF Downloads 1461145 Experimental Investigation of Air-Water Two-Phase Flow Pattern in T-Junction Microchannel
Authors: N. Rassoul-ibrahim, E. Siahmed, L. Tadrist
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Water management plays a crucial role in the performance and durability of PEM fuel cells. Whereas the membrane must be hydrated enough, liquid droplets formed by water in excess can block the flow in the gas distribution channels and hinder the fuel cell performance. The main purpose of this work is to increase the understanding of liquid transport and mixing through mini- or micro-channels for various engineering or medical process applications including cool-ing of equipment according to the operations considered. For that purpose and as a first step, a technique was devel-oped to automatically detect and characterize two-phase flow patterns that may appear in such. The investigation, mainly experimental, was conducted on transparent channel with a 1mm x 1mm square cross section and a 0.3mm x 0.3 mm water injection normal to the gas channel. Three main flow patterns were identified liquid slug, bubble flow and annular flow. A flow map has been built accord-ing to the flow rate of both phases. As a sample the follow-ing figures show representative images of the flow struc-tures observed. An analysis and discussion of the flow pattern, in mini-channel, will be provided and compared to the case old micro-channel. . Keywords: Two phase flow, Clean Energy, Minichannels, Fuel Cells. Flow patterns, Maps.Keywords: two phase flox, T-juncion, Micro and minichannels, clean energy, flow patterns, maps
Procedia PDF Downloads 761144 Haplotypes of the Human Leukocyte Antigen-G Different HIV-1 Groups from the Netherlands
Authors: A. Alyami, S. Christmas, K. Neeltje, G. Pollakis, B. Paxton, Z. Al-Bayati
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The Human leukocyte antigen-G (HLA-G) molecule plays an important role in immunomodulation. To date, 16 untranslated regions (UTR) HLA-G haplotypes have been previously defined by sequenced SNPs in the coding region. From these, UTR-1, UTR-2, UTR-3, UTR-4, UTR-5, UTR-6 and UTR-7 are the most frequent 3’UTR haplotypes at the global level. UTR-1 is associated with higher levels of soluble HLA-G and HLA-G expression, whereas UTR-5 and UTR-7 are linked with low levels of soluble HLA-G and HLA-G expression. Human immunodeficiency virus type 1 (HIV-1) infection results in the progressive loss of immune function in infected individuals. The virus escape mechanism typically includes T lymphocytes and NK cell recognition and lyses by classical HLA-A and B down-regulation, which has been associated with non-classical HLA-G molecule up-regulation, respectively. We evaluated the haplotypes of the HLA-G 3′ untranslated region frequencies observed in three HIV-1 groups from the Netherlands and their susceptibility to develop infection. The three groups are made up of mainly men who have sex with men (MSM), injection drug users (IDU) and a high-risk-seronegative (HRSN) group. DNA samples were amplified with published primers prior sequencing. According to our results, the low expresser frequencies show higher in HRSN compared to other groups. This is indicating that 3’UTR polymorphisms may be identified as potential prognostic biomarkers to determine susceptibility to HIV.Keywords: Human leukocyte antigen-G (HLA-G) , men who have sex with men (MSM), injection drug users (IDU), high-risk-seronegative (HRSN) group, high-untranslated region (UTR)
Procedia PDF Downloads 1531143 Transcriptional Profiling of Developing Ovules in Litchi chinensis
Authors: Ashish Kumar Pathak, Ritika Sharma, Vishal Nath, Sudhir Pratap Singh, Rakesh Tuli
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Litchi is a sub-tropical fruit crop with genotypes bearing delicious juicy fruits with variable seed size (bold to rudimentary size). Small seed size is a desirable trait in litchi, as it increases consumer acceptance and fruit processing. The biochemical activities in mid- stage ovules (e.g. 16, 20, 24 and 28 days after anthesis) determine the fate of seed and fruit development in litchi. Comprehensive ovule-specific transcriptome analysis was performed in two litchi genotypes with contrasting seed size to gain molecular insight on determinants of seed fates in litchi fruits. The transcriptomic data was de-novo assembled in 1,39,608 trinity transcripts, out of which 6,325 trinity transcripts were differentially expressed between the two contrasting genotypes. Differential transcriptional pattern was found among ovule development stages in contrasting litchi genotypes. The putative genes for salicylic acid, jasmonic acid and brassinosteroid pathway were down-regulated in ovules of small-seeded litchi. Embryogenesis, cell expansion, seed size and stress related trinity transcripts exhibited altered expression in small-seeded genotype. The putative regulators of seed maturation and seed storage were down-regulated in small-seed genotype.Keywords: Litchi, seed, transcriptome, defence
Procedia PDF Downloads 2441142 Impact of U.S. Insurance Reimbursement Policy on Healthcare Business and Entrepreneurship
Authors: Iris Xiaohong Quan, Sharon Qi, Kelly Tianqin Shi
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This study focuses on the critical role of insurance policies in a world grappling with increasing mental health challenges, as they significantly influence the dynamics of healthcare businesses and entrepreneurial ventures. The paper utilizes the mental health sector as a case to examine the impact of insurance policies on healthcare service providers, entrepreneurs, and individuals seeking mental health support. This paper addressed the following research questions: To what extent do changes in insurance reimbursement policies affect the accessibility and affordability of mental health services for patients, and how does this impact the overall demand for such services? What are the barriers and opportunities that mental health entrepreneurs face and what strategies and adaptations do mental health businesses employ when navigating the evolving landscape of insurance reimbursement policies? How do changes in insurance reimbursement policies, specifically related to mental health services, influence the financial viability and sustainability of mental health clinics and private practices? Employing a self-designed survey aimed at autism spectrum disorder (ASD) treatment companies, alongside two in-depth case studies and an analysis of pertinent insurance policies and documents, this research aims to elucidate the multifaceted influence of insurance policies on the mental health industry. The findings from this study reveal how insurance policies shape the landscape of mental health businesses and their operations. A total of 821 autism treatment organizations or offices were contacted by telephone between November 1, 2019, and January 31, 2020. About half of the offices (53.33%) were established in the past five years, and 80% were established in the past 15 years. There is a significant increase in the establishment of ABA service centers in the recent two decades as a result of autism insurance reform, the increasing social awareness of ASD, and the redefinition of autism. In addition, almost half of the ABA service providers we surveyed had a patient size ranging from 20 to 50 in the year when the residence state passed the legislation for autism insurance coverage. On average, an ABA service provider works with 5.3 insurance companies. This research find that insurance is the main source of revenue for most ABA service providers. However, our survey reveals that clients’ out of pocket payment has been the second main revenue sources. Despite the changes of regulations and insurance policies in all states, clients still have to pay a fraction of, if not all, the ABA treatment service fees out of pocket. This research shows that some ABA service providers seek federal and government funds and grants to support their services and businesses. Our further analysis with the in-depth case studies and other secondary data also indicate the rise of entrepreneurial startups in the mental health industry. Overall, this research sheds light on both the challenges and opportunities presented by insurance policies in the mental health sector, offering insights into the new industry landscape.Keywords: entrepreneurship, healthcare policy, insurance policy, mental health industry
Procedia PDF Downloads 571141 Surface Modification of TiO2 Layer with Phosphonic Acid Monolayer in Perovskite Solar Cells: Effect of Chain Length and Terminal Functional Group
Authors: Seid Yimer Abate, Ding-Chi Huang, Yu-Tai Tao
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In this study, charge extraction characteristics at the perovskite/TiO2 interface in the conventional perovskite solar cell is studied by interface engineering. Self-assembled monolayers of phosphonic acids with different chain length and terminal functional group were used to modify mesoporous TiO2 surface to modulate the surface property and interfacial energy barrier to investigate their effect on charge extraction and transport from the perovskite to the mp-TiO2 and then the electrode. The chain length introduces a tunnelling distance and the end group modulate the energy level alignment at the mp-TiO2 and perovskite interface. The work function of these SAM-modified mp-TiO2 varied from −3.89 eV to −4.61 eV, with that of the pristine mp-TiO2 at −4.19 eV. A correlation of charge extraction and transport with respect to the modification was attempted. The study serves as a guide to engineer ETL interfaces with simple SAMs to improve the charge extraction, carrier balance and device long term stability. In this study, a maximum PCE of ~16.09% with insignificant hysteresis was obtained, which is 17% higher than the standard device.Keywords: Energy level alignment, Interface engineering, Perovskite solar cells, Phosphonic acid monolayer, Tunnelling distance
Procedia PDF Downloads 1371140 The Interplay of Dietary Fibers and Intestinal Microbiota Affects Type 2 Diabetes by Generating Short-Chain Fatty Acids
Authors: Muhammad Mazhar, Yong Zhu, Likang Qin
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Foods contain endogenous components known as dietary fibers, which are classified into soluble and insoluble forms. Dietary fibers are resistant to gut digestive enzymes, modulating anaerobic intestinal microbiota (AIM) and fabricating short-chain fatty acids (SCFAs). Acetate, butyrate, and propionate dominate in the gut, and different pathways, including Wood-Ljungdahl and acrylate pathways, generate these SCFAs. In pancreatic dysfunction, the release of insulin/glucagon is impaired, which leads to hyperglycemia. SCFAs enhance insulin sensitivity or secretion, beta-cell functions, leptin release, mitochondrial functions, and intestinal gluconeogenesis in human organs, which positively affect type 2 diabetes (T2D). Research models presented that SCFAs either enhance the release of peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) from L-cells (entero-endocrine) or promote the release of leptin hormone satiation in adipose tissues through G-protein receptors, i.e., GPR-41/GPR-43. Dietary fibers are the components of foods that influence AIM and produce SCFAs, which may be offering beneficial effects on T2D. This review addresses the effectiveness of SCFAs in modulating gut AIM in the fermentation of dietary fiber and their worth against T2D.Keywords: dietary fibers, intestinal microbiota, short-chain fatty acids, fermentation, type 2 diabetes
Procedia PDF Downloads 731139 Design and Implementation of a 94 GHz CMOS Double-Balanced Up-Conversion Mixer for 94 GHz Imaging Radar Sensors
Authors: Yo-Sheng Lin, Run-Chi Liu, Chien-Chu Ji, Chih-Chung Chen, Chien-Chin Wang
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A W-band double-balanced mixer for direct up-conversion using standard 90 nm CMOS technology is reported. The mixer comprises an enhanced double-balanced Gilbert cell with PMOS negative resistance compensation for conversion gain (CG) enhancement and current injection for power consumption reduction and linearity improvement, a Marchand balun for converting the single LO input signal to differential signal, another Marchand balun for converting the differential RF output signal to single signal, and an output buffer amplifier for loading effect suppression, power consumption reduction and CG enhancement. The mixer consumes low power of 6.9 mW and achieves LO-port input reflection coefficient of -17.8~ -38.7 dB and RF-port input reflection coefficient of -16.8~ -27.9 dB for frequencies of 90~100 GHz. The mixer achieves maximum CG of 3.6 dB at 95 GHz, and CG of 2.1±1.5 dB for frequencies of 91.9~99.4 GHz. That is, the corresponding 3 dB CG bandwidth is 7.5 GHz. In addition, the mixer achieves LO-RF isolation of 36.8 dB at 94 GHz. To the authors’ knowledge, the CG, LO-RF isolation and power dissipation results are the best data ever reported for a 94 GHz CMOS/BiCMOS up-conversion mixer.Keywords: CMOS, W-band, up-conversion mixer, conversion gain, negative resistance compensation, output buffer amplifier
Procedia PDF Downloads 5311138 MiR-103 Inhibits Osteoblast Proliferation Mainly through Suppressing Cav 1.2 Expression in Simulated Microgravity
Authors: Zhongyang Sun, Shu Zhang, Manjiang Xie
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Emerging evidence indicates that microRNAs (miRNAs) play important roles in modulating osteoblast function and bone formation. However, the influence of miRNA on osteoblast proliferation and the possible mechanisms underlying remain to be defined. In this study, we aimed to investigate whether miR-103 regulates osteoblast proliferation under simulated microgravity condition through regulating Cav1.2, the primary subunit of L-type voltage sensitive calcium channels (LTCCs). We first investigated the effect of simulated microgravity on osteoblast proliferation and the outcomes clearly demonstrated that the mechanical unloading inhibits MC3T3-E1 osteoblast-like cells proliferation. Using quantitative Real-Time PCR (qRT-PCR), we provided data showing that miR-103 was up-regulated in response to simulated microgravity. In addition, we observed that up-regulation of miR-103 inhibited and down-regulation of miR-103 promoted osteoblast proliferation under simulated microgravity condition. Furthermore, knocking-down or over-expressing miR-103, respectively, up- or down-regulated the level of Cav1.2 expression and LTCCs currents, suggesting that miR-103 acts as an endogenous attenuator of Cav1.2 in osteoblasts under the condition of simulated microgravity. More importantly, we showed that the effect of miR-103 on osteoblast proliferation was diminished in simulated microgravity, when co-transfecting miR-103 mimic or inhibitor with Cav1.2 siRNA. Taken together, our data suggest that miR-103 inhibits osteoblast proliferation mainly through suppression of Cav1.2 expression under simulated microgravity condition. This work may provide a novel mechanism of microgravity-induced detrimental effects on osteoblast, identifying miR-103 as a novel possible therapeutic target in bone remodeling disorders in this mechanical unloading.Keywords: microRNA, osteoblasts, cell proliferation, Cav1.2, simulated microgravity
Procedia PDF Downloads 3661137 3D Carbon Structures (Globugraphite) with Hierarchical Pore Morphology for the Application in Energy Storage Systems
Authors: Hubert Beisch, Janik Marx, Svenja Garlof, Roman Shvets, Ivan Grygorchak, Andriy Kityk, Bodo Fiedler
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Three-dimensional carbon materials can be used as electrode materials for energy storage systems such as batteries and supercapacitors. Fast charging and discharging times are realizable without reducing the performance due to aging processes. Furthermore high specific surface area (SSA) of three-dimensional carbon structures leads to high specific capacities. One newly developed carbon foam is Globugraphite. This interconnected globular carbon morphology with statistically distributed hierarchical pores is manufactured by a chemical vapor deposition (CVD) process from ceramic templates resulting from a sintering process. Via scanning electron (SEM) and transmission electron microscopy (TEM), the morphology is characterized. Moreover, the SSA was measured by the Brunauer–Emmett–Teller (BET) theory. Measurements of Globugraphite in an organic and inorganic electrolyte show high energy densities and power densities resulting from ion absorption by forming an electrochemical double layer. A comparison of the specific values is summarized in a Ragone diagram. Energy densities up to 48 Wh/kg and power densities to 833 W/kg could be achieved for an SSA from 376 m²/g to 859 m²/g. For organic electrolyte, a specific capacity of 100 F/g at a density of 20 mg/cm³ was achieved.Keywords: BET, carbon foam, CVD process, electrochemical cell, Ragone diagram, SEM, TEM
Procedia PDF Downloads 2341136 Path Planning for Orchard Robot Using Occupancy Grid Map in 2D Environment
Authors: Satyam Raikwar, Thomas Herlitzius, Jens Fehrmann
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In recent years, the autonomous navigation of orchard and field robots is an emerging technology of the mobile robotics in agriculture. One of the core aspects of autonomous navigation builds upon path planning, which is still a crucial issue. Generally, for simple representation, the path planning for a mobile robot is performed in a two-dimensional space, which creates a path between the start and goal point. This paper presents the automatic path planning approach for robots used in orchards and vineyards using occupancy grid maps with field consideration. The orchards and vineyards are usually structured environment and their topology is assumed to be constant over time; therefore, in this approach, an RGB image of a field is used as a working environment. These images undergone different image processing operations and then discretized into two-dimensional grid matrices. The individual grid or cell of these grid matrices represents the occupancy of the space, whether it is free or occupied. The grid matrix represents the robot workspace for motion and path planning. After the grid matrix is described, a probabilistic roadmap (PRM) path algorithm is used to create the obstacle-free path over these occupancy grids. The path created by this method was successfully verified in the test area. Furthermore, this approach is used in the navigation of the orchard robot.Keywords: orchard robots, automatic path planning, occupancy grid, probabilistic roadmap
Procedia PDF Downloads 1551135 White-Rot Fungi Phellinus as a Source of Antioxidant and Antitumor Agents
Authors: Yogesh Dalvi, Ruby Varghese, Nibu Varghese, C. K. Krishnan Nair
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Introduction: The Genus Phellinus, locally known as Phansomba is a well-known traditional folk medicine. Especially, in Western Ghats of India, many tribes use several species of Phellinus for various ailments related to teeth, throat, tongue, stomach and even wound healing. It is one of the few mushrooms which play a pivotal role in Ayurvedic Dravyaguna. Aim: The present study focuses on to investigate phytochemical analysis, antioxidant, and antitumor (in vitro and in vivo) potential of Phellinus robinae from South India, Kerala Material and Methods: The present study explores the following: 1. Phellinus samples were collected from Ranni, Pathanamthitta district of Kerala state, India from Artocarpus heterophyllus Lam. and species were identified using rDNA region. 2. The fruiting body was shadow dried, powdered and extracted with 50% alcohol using water bath at 60°C which was further condensed by rotary evaporator and lyophilized at minus 40°C temperature. 3. Secondary metabolites were analyzed by using various phytochemical screening assay (Hager’s Test, Wagner’s Test, Sodium hydroxide Test, Lead acetate Test, Ferric chloride Test, Folin-ciocalteu Test, Foaming Test, Benedict’s test, Fehling’s Test and Lowry’s Test). 4. Antioxidant and free radical scavenging activity were analyzed by DPPH, FRAP and Iron chelating assay. 5. The antitumor potential of Water alcohol extract of Phellinus (PAWE) is evaluated through In vitro condition by Trypan blue dye exclusion method in DLA cell line and In vivo by murine model. Result and Discussion: Preliminary phytochemical screening by various biochemical tests revealed presence of a variety of active secondary molecules like alkaloids, flavanoids, saponins, carbohydrate, protein and phenol. In DPPH and FRAP assay PAWE showed significantly higher antioxidant activity as compared to standard Ascorbic acid. While, in Iron chelating assay, PAWE exhibits similar antioxidant activity that of Butylated Hydroxytoluene (BHT) as standard. Further, in the in vitro study, PAWE showed significant inhibition on DLA cell proliferation in dose dependent manner and showed no toxicity on mice splenocytes, when compared to standard chemotherapy drug doxorubicin. In vivo study, oral administration of PAWE showed dose dependent tumor regression in mice and also raised the immunogenicity by restoring levels of antioxidant enzymes in liver and kidney tissue. In both in vitro and in vivo gene expression studies PAWE up-regulates pro-apoptotic genes (Bax, Caspases 3, 8 and 9) and down- regulates anti-apoptotic genes (Bcl2). PAWE also down regulates inflammatory gene (Cox-2) and angiogenic gene (VEGF). Conclusion: Preliminary phytochemical screening revealed that PAWE contains various secondary metabolites which contribute to its antioxidant and free radical scavenging property as evaluated by DPPH, FRAP and Iron chelating assay. PAWE exhibits anti-proliferative activity by the induction of apoptosis through a signaling cascade of death receptor-mediated extrinsic (Caspase8 and Tnf-α), as well as mitochondria-mediated intrinsic (caspase9) and caspase pathways (Caspase3, 8 and 9) and also by regressing angiogenic factor (VEGF) without any inflammation or adverse side effects. Hence, PAWE serve as a potential antioxidant and antitumor agent.Keywords: antioxidant, antitumor, Dalton lymphoma ascites (DLA), fungi, Phellinus robinae
Procedia PDF Downloads 3041134 Static Characterization of a Bio-Based Sandwich in a Humid Environment
Authors: Zeineb Kesentini, Abderrahim El Mahi, Jean Luc Rebiere, Rachid El Guerjouma, Moez Beyaoui, Mohamed Haddar
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Industries’ attention has been drawn to green and sustainable materials as a result of the present energy deficit and environmental damage. Sandwiches formed of auxetic structures made up of periodic cells are also being investigated by industry. Several tests have emphasized the exceptional properties of these materials. In this study, the sandwich's core is a one-cell auxetic core. Among plant fibers, flax fibers are chosen because of their good mechanical properties comparable to those of glass fibers. Poly (lactic acid) (PLA), as a green material, is available from starch, and its production process requires fewer fossil resources than petroleum-based plastics. A polylactic acid (PLA) reinforced with flax fiber filament was employed in this study. The manufacturing process used to manufacture the test specimens is 3D printing. The major drawback of a 100% bio-based material is its low resistance to moisture absorption. In this study, a sandwich based on PLA / flax with an auxetic core is characterized statically for different periods of immersion in water. Bending tests are carried out on the composite sandwich for three immersion time. Results are compared to those of non immersed specimens. It is found that non aged sandwich has the ultimate bending stiffness.Keywords: auxetic, bending tests, biobased composite, sandwich structure, 3D printing
Procedia PDF Downloads 1531133 Synthesis and Applications of Biosorbent from Barley Husk for Adsorption of Heavy Metals and Bacteria from Water
Authors: Sudarshan Kalsulkar, Sunil S. Bhagwat
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Biosorption is a physiochemical process that occurs naturally in certain biomass which allows it to passively concentrate and bind contaminants onto its cellular structure. Activated carbons (AC) are one such efficient biosorbents made by utilizing lignocellulosic materials from agricultural waste. Steam activated carbon (AC) was synthesized from Barley husk. Its synthesis parameters of time and temperature were optimized. Its physico-chemical properties like density, surface area, pore volume, Methylene blue and Iodine values were characterized. BET surface area was found to be 42 m²/g. Batch Adsorption tests were carried out to determine the maximum adsorption capacity (qmax) for various metal ions. Cd+2 48.74 mg/g, Pb+2 19.28 mg/g, Hg+2 39.1mg/g were the respective qmax values. pH and time were optimized for adsorption of each ion. Column Adsorptions were carried for each to obtain breakthrough data. Microbial adsorption was carried using E. coli K12 strain. 78% reduction in cell count was observed at operating conditions. Thus the synthesized Barley husk AC can be an economically feasible replacement for commercially available AC prepared from the costlier coconut shells. Breweries and malting industries where barley husk is a primary waste generated on a large scale can be a good source for bulk raw material.Keywords: activated carbon, Barley husk, biosorption, decontamination, heavy metal removal, water treatment
Procedia PDF Downloads 4151132 A Kernel-Based Method for MicroRNA Precursor Identification
Authors: Bin Liu
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MicroRNAs (miRNAs) are small non-coding RNA molecules, functioning in transcriptional and post-transcriptional regulation of gene expression. The discrimination of the real pre-miRNAs from the false ones (such as hairpin sequences with similar stem-loops) is necessary for the understanding of miRNAs’ role in the control of cell life and death. Since both their small size and sequence specificity, it cannot be based on sequence information alone but requires structure information about the miRNA precursor to get satisfactory performance. Kmers are convenient and widely used features for modeling the properties of miRNAs and other biological sequences. However, Kmers suffer from the inherent limitation that if the parameter K is increased to incorporate long range effects, some certain Kmer will appear rarely or even not appear, as a consequence, most Kmers absent and a few present once. Thus, the statistical learning approaches using Kmers as features become susceptible to noisy data once K becomes large. In this study, we proposed a Gapped k-mer approach to overcome the disadvantages of Kmers, and applied this method to the field of miRNA prediction. Combined with the structure status composition, a classifier called imiRNA-GSSC was proposed. We show that compared to the original imiRNA-kmer and alternative approaches. Trained on human miRNA precursors, this predictor can achieve an accuracy of 82.34 for predicting 4022 pre-miRNA precursors from eleven species.Keywords: gapped k-mer, imiRNA-GSSC, microRNA precursor, support vector machine
Procedia PDF Downloads 1611131 Synthesis of Chitosan/Silver Nanocomposites: Antibacterial Properties and Tissue Regeneration for Thermal Burn Injury
Authors: B.L. España-Sánchez, E. Luna-Hernández, R.A. Mauricio-Sánchez, M.E. Cruz-Soto, F. Padilla-Vaca, R. Muñoz, L. Granados-López, L.R. Ovalle-Flores, J.L. Menchaca-Arredondo, G. Luna-Bárcenas
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Treatment of burn injured has been considered an important clinical problem due to the fluid control and the presence of microorganisms during the healing process. Conventional treatment includes antiseptic techniques, topical medication and surgical removal of damaged skin, to avoid bacterial growth. In order to accelerate this process, different alternatives for tissue regeneration have been explored, including artificial skin, polymers, hydrogels and hybrid materials. Some requirements consider a nonreactive organic polymer with high biocompatibility and skin adherence, avoiding bacterial infections. Chitin-derivative biopolymer such as chitosan (CS) has been used in skin regeneration following third-degree burns. The biological interest of CS is associated with the improvement of tissue cell stimulation, biocompatibility and antibacterial properties. In particular, antimicrobial properties of CS can be significantly increased when is blended with nanostructured materials. Silver-based nanocomposites have gained attention in medicine due to their high antibacterial properties against pathogens, related to their high surface area/volume ratio at nanomolar concentrations. Silver nanocomposites can be blended or synthesized with chitin-derivative biopolymers in order to obtain a biodegradable/antimicrobial hybrid with improved physic-mechanical properties. In this study, nanocomposites based on chitosan/silver nanoparticles (CS/nAg) were synthesized by the in situ chemical reduction method, improving their antibacterial properties against pathogenic bacteria and enhancing the healing process in thermal burn injuries produced in an animal model. CS/nAg was prepared in solution by the chemical reduction method, using AgNO₃ as precursor. CS was dissolved in acetic acid and mixed with different molar concentrations of AgNO₃: 0.01, 0.025, 0.05 and 0.1 M. Solutions were stirred at 95°C during 20 hours, in order to promote the nAg formation. CS/nAg solutions were placed in Petri dishes and dried, to obtain films. Structural analyses confirm the synthesis of silver nanoparticles (nAg) by means of UV-Vis and TEM, with an average size of 7.5 nm and spherical morphology. FTIR analyses showed the complex formation by the interaction of hydroxyl and amine groups with metallic nanoparticles, and surface chemical analysis (XPS) shows low concentration of Ag⁰/Ag⁺ species. Topography surface analyses by means of AFM shown that hydrated CS form a mesh with an average diameter of 10 µm. Antibacterial activity against S. aureus and P. aeruginosa was improved in all evaluated conditions, such as nAg loading and interaction time. CS/nAg nanocomposites films did not show Ag⁰/Ag⁺ release in saline buffer and rat serum after exposition during 7 days. Healing process was significantly enhanced by the presence of CS/nAg nanocomposites, inducing the production of myofibloblasts, collagen remodelation, blood vessels neoformation and epidermis regeneration after 7 days of injury treatment, by means of histological and immunohistochemistry assays. The present work suggests that hydrated CS/nAg nanocomposites can be formed a mesh, improving the bacterial penetration and the contact with embedded nAg, producing complete growth inhibition after 1.5 hours. Furthermore, CS/nAg nanocomposites improve the cell tissue regeneration in thermal burn injuries induced in rats. Synthesis of antibacterial, non-toxic, and biocompatible nanocomposites can be an important issue in tissue engineering and health care applications.Keywords: antibacterial, chitosan, healing process, nanocomposites, silver
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