Search results for: contact resistance

Authors: Amerah Alsalem

Abstract:

Aim: Laminate veneers are restorations which are envisioned to correct existing abnormalities, esthetic deficiencies, and discolorations. Laminate veneer restorations may be processed in two different ways: direct or indirect. Materials and methods: Direct composite laminate veneers require minimal preparation compared to indirect composite veneers, cost less and are easier to repair, so are useful in young patients. However, composites can have inherent limitations such as shrinkage, limited toughness; color instability and susceptibility to wear that reduce the lifespan of the restoration and cause postoperative complications. Every new material or method introduced to the field of dentistry aims to achieve esthetics and successful dental treatments with minimal invasiveness. Therefore, direct laminate veneer restorations have been developed for advanced esthetic problems of anterior teeth. Tooth discolorations, rotated teeth, coronal fractures, congenital or acquired malformations, diastemas, discolored restorations, palatally positioned teeth, the absence of lateral incisors, abrasions and erosions are the main indications for direct laminate veneer restorations. Result: Direct veneers, as esthetic procedures, have become treatment alternatives for patients with esthetic problems of anterior teeth in recent years. The cost, social and time factors have to be considered. Although ceramic laminate veneer restorations have some advantages like color stability and high resistance against abrasion, they have also some disadvantages, including high cost and long chair time. Moreover, they have some problems such as the necessity of an additional adhesive cement. Conclusion: Although there are still some disadvantages, especially discolorations and fragility, with the development of new composite resins, direct laminate veneer restorations can be a treatment option for patients with esthetic problems of anterior teeth, when applied judiciously with good patient hygiene motivation.

Keywords: direct, veneers, composite, anterior

Procedia PDF Downloads 256

Authors: Emmanuel Olugbenga Fakoya

Abstract:

The study examined the perceived impact of climate change on the livelihood of arable crop farmers in Ipokia Local Government Area of Ogun State, Nigeria. Multistage sampling technique was used to select 80 arable crop farmers in the study area. Data collected were analyzed using percentages, frequencies and Chi square analysis. The result showed that 63.8 percent of the respondents were male while 55.0 percent were married. Less than half (30.0 percent) of the respondents were between the age bracket of 41-50 years and 50.0 percent had 6-10 household size. Furthermore, majority (40.0 percent) of the arable crop farmers farmed on an inherited land and 51.3 percent had 2-3 hectares of land. Majority (38.8 percent) of the farmers intercrop maize with cassava and maize with yam. Various strategies adapted to reduce the effect of climate change on their crop and livelihood include: crop rotation (53.8 percent), planting of leguminous crop (35.0 percent), application of organic fertilizers (45.0 percent), mulching (56.3 percent) and by planting drought resistance crops (46.5 percent). Reported among the effects of climate change on crop and farmers’ livelihood were: discoloration of crop leave (63.8 percent), increase infestation of pests and diseases (58.8 percent) and reduction of crop yield (60.0 percent). Chi- square analysis showed significant relationship between impact of climate change on arable crop production and thus famers’ livelihood. It was concluded from the study that climate change is an impinging factor that seriously affect arable crop production and hence farmers’ livelihood despite coping strategies to minimize its effect. It was however recommended that Agricultural policies and practices that could minimize or eliminate its effect should be seriously enacted to boost production and increase farmers’ livelihood.

Keywords: agricultural extension, extension agent, private sector, perception

Procedia PDF Downloads 420

Authors: Włodzimierz Przewodowski, Agnieszka Przewodowska

Abstract:

Colloidal metal nanoparticles have drawn increasing attention in the field of phytopathology because of their unique properties and possibilities of applications. Their antibacterial activity, no induction of the development of pathogen resistance and the ability to penetrate most of biological barriers make them potentially useful in the fighting against dangerous pathogens. These properties are very important in the case of protection of strategic crops in the world, like potato - fourth crop in the world - which is host to numerous pathogenic microorganisms causing serious diseases, significantly affecting yield and causing the economic losses. One of the most important and difficult to reduce pathogen of potato plant is quarantine bacterium Clavibacter michiganensis ssp. sepedonicus (Cms) responsible for ring rot disease. Control and detection of these pathogens is very complicated. Application of healthy, certified seed material as well as hygiene in potato production and storage are the most efficient ways of preventing of ring rot disease. Currently used disinfectants and pesticides, have many disadvantages, such as toxicity, low efficiency, selectivity, corrosiveness, and the inability to eliminate the pathogens in potato tissue. In this situation, it becomes important to search for new formulations based on components harmful to health, yet efficient, stable during prolonged period of time and a with wide range of biocide activity. Such capabilities are offered by the latest generation of biocidal nanoparticles such as colloidal metals. Therefore the aim of the presented research was to develop newly antibacterial preparation based on colloidal metal nanoparticles and checking their influence on the Cms bacteria. Our preliminary results confirmed high efficacy of the nano-colloids in controlling the this selected pathogen.

Keywords: clavibacter michiganensis ssp. sepedonicus, colloidal metal nanoparticles, phytopathology, bacteria

Procedia PDF Downloads 245

Authors: Helen K. Buteme, Rebecca Axelsson-Robertson, Moses L. Joloba, Henry W. Boom, Gunilla Kallenius, Markus Maeurer

Abstract:

Background: The Ugandan population is heavily affected by infectious diseases and Human leukocyte antigen (HLA) diversity plays a crucial role in the host-pathogen interaction and affects the rates of disease acquisition and outcome. The identification of HLA class 1 alleles and determining which alleles are associated with tuberculosis (TB) outcomes would help in screening individuals in TB endemic areas for susceptibility to TB and to predict resistance or progression to TB which would inevitably lead to better clinical management of TB. Aims: To be able to determine the HLA class 1 phenotype distribution in a Ugandan TB cohort and to establish the relationship between these phenotypes and active and latent TB. Methods: Blood samples were drawn from 32 HIV negative individuals with active TB and 45 HIV negative individuals with latent MTB infection. DNA was extracted from the blood samples and the DNA samples HLA typed by the polymerase chain reaction-sequence specific primer method. The allelic frequencies were determined by direct count. Results: HLA-A*02, A*01, A*74, A*30, B*15, B*58, C*07, C*03 and C*04 were the dominant phenotypes in this Ugandan cohort. There were differences in the distribution of HLA types between the individuals with active TB and the individuals with LTBI with only HLA-A*03 allele showing a statistically significant difference (p=0.0136). However, after FDR computation the corresponding q-value is above the expected proportion of false discoveries (q-value 0.2176). Key findings: We identified a number of HLA class I alleles in a population from Central Uganda which will enable us to carry out a functional characterization of CD8+ T-cell mediated immune responses to MTB. Our results also suggest that there may be a positive association between the HLA-A*03 allele and TB implying that individuals with the HLA-A*03 allele are at a higher risk of developing active TB.

Keywords: HLA, phenotype, tuberculosis, Uganda

Procedia PDF Downloads 381

Authors: Thobela Conco, Sheena Kumari, Thor Stenstrom, Simona Rosetti, Valter Tandoi, Faizal Bux

Abstract:

Filamentous bacteria are well documented as causative agents of bulking and foaming in the biological wastewater treatment process. These filamentous bacteria are however closely associated with other non-filamentous organism forming a micro-niche. Among these specific epiphytic bacteria attach to filaments in the consortium of organisms that make up the floc. Neither the eco-physiological role of the epiphytes nor the nature of the interaction between the epiphytic bacteria and the filament hosts they colonize is well understood and in need of in-depth investigations. The focus of this presentation is on the interaction between the epiphytic bacteria and the filament host. Samples from the activated sludge treatment have been repeatedly collected from several wastewater treatment plants in KwaZulu Natal. Extensive investigations have been performed with SEM and TEM electron microscopy, Polarized Light Microscopy with Congo red staining, and Thioflavin T staining to document the interaction. SEM was used to document the morphology of both the filament host and their epiphytes counterparts with the focus on the interface/point of contact between the two, while the main focus of the TEM investigations with the higher magnification aimed to document the ultra-structure features of two organisms relating to the interaction. The interaction of the perpendicular attachment partly seems to be governed by the physiological status of the filaments. The attachment further seems to trigger a response in the filaments with distinct internal visible structures at the attachment sites. It is postulated that these structures most likely are amyloid fibrils. Amyloid fibrils may play an overarching role in different types of attachments and has earlier been noted to play a significant role in biofilm formation in activated sludge. They also play a medical role in degenerative diseases such as Alzheimer’s and Diabetes. Further studies aims to define the eco-physiological role of amyloid fibrils in filamentous bacteria, based on their observed presence at interaction sites in this study. This will also relate to additional findings where selectivity within the species of epiphytes attaching to the selected filaments has been noted. The practical implications of the research findings is still to be determined, but the ecophysiological interaction between two closely associated species or groups may have significant impact in the future understanding of wastewater treatment processes and broaden existing knowledge on population dynamics.

Keywords: activated sludge, amyloid proteins, epiphytic bacteria, filamentous bacteria

Procedia PDF Downloads 390

Authors: Abdulqader Alkhouzaam, Hazim Qiblawey, Majeda Khraisheh

Abstract:

Membrane treatment for desalination and wastewater treatment is one of the promising solutions to affordable clean water. It is a developing technology throughout the world and considered as the most effective and economical method available. However, the limitations of membranes’ mechanical and chemical properties restrict their industrial applications. Hence, developing novel membranes was the focus of most studies in the water treatment and desalination sector to find new materials that can improve the separation efficiency while reducing membrane fouling, which is the most important challenge in this field. Graphene oxide (GO) is one of the materials that have been recently investigated in the membrane water treatment sector. In this work, ultrafiltration polysulfone (PSF) membranes with high antifouling properties were synthesized by incorporating different loadings of GO. High-oxidation degree GO had been synthesized using a modified Hummers' method. The synthesized GO was characterized using different analytical techniques including elemental analysis, Fourier transform infrared spectroscopy - universal attenuated total reflectance sensor (FTIR-UATR), Raman spectroscopy, and CHNSO elemental analysis. CHNSO analysis showed a high oxidation degree of GO represented by its oxygen content (50 wt.%). Then, ultrafiltration PSF membranes incorporating GO were fabricated using the phase inversion technique. The prepared membranes were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM) and showed a clear effect of GO on PSF physical structure and morphology. The water contact angle of the membranes was measured and showed better hydrophilicity of GO membranes compared to pure PSF caused by the hydrophilic nature of GO. Separation properties of the prepared membranes were investigated using a cross-flow membrane system. Antifouling properties were studied using bovine serum albumin (BSA) and humic acid (HA) as model foulants. It has been found that GO-based membranes exhibit higher antifouling properties compared to pure PSF. When using BSA, the flux recovery ratio (FRR %) increased from 65.4 ± 0.9 % for pure PSF to 84.0 ± 1.0 % with a loading of 0.05 wt.% GO in PSF. When using HA as model foulant, FRR increased from 87.8 ± 0.6 % to 93.1 ± 1.1 % with 0.02 wt.% of GO in PSF. The pure water permeability (PWP) decreased with loadings of GO from 181.7 L.m⁻².h⁻¹.bar⁻¹ of pure PSF to 181.1, and 157.6 L.m⁻².h⁻¹.bar⁻¹ with 0.02 and 0.05 wt.% GO respectively. It can be concluded from the obtained results that incorporating low loading of GO could enhance the antifouling properties of PSF hence improving its lifetime and reuse.

Keywords: antifouling properties, GO based membranes, hydrophilicity, polysulfone, ultrafiltration

Procedia PDF Downloads 120

Authors: Saniye Çeşmecioğlu

Abstract:

The importance of project sustainability and success has become increasingly significant due to the proliferation of external environmental factors that have decreased project resistance in contemporary times. The primary approach to forestall the failure of projects is to ensure their long-term viability through the strategic selection of projects as creating judicious project selection framework within the organization. Decision-makers require precise decision contexts (models) that conform to the company's business objectives and sustainability expectations during the project selection process. The establishment of a rational model for project selection enables organizations to create a distinctive and objective framework for the selection process. Additionally, for the optimal implementation of this decision-making model, it is crucial to establish a Project Management Office (PMO) team and Project Steering Committee within the organizational structure to oversee the framework. These teams enable updating project selection criteria and weights in response to changing conditions, ensuring alignment with the company's business goals, and facilitating the selection of potentially viable projects. This paper presents a multi-criteria decision model for selecting project sustainability and project success criteria that ensures timely project completion and retention. The model was developed using MACBETH (Measuring Attractiveness by a Categorical Based Evaluation Technique) and was based on broadcaster companies’ expectations. The ultimate results of this study provide a model that endorses the process of selecting the appropriate project objectively by utilizing project selection and sustainability criteria along with their respective weights for organizations. Additionally, the study offers suggestions that may ascertain helpful in future endeavors.

Keywords: project portfolio management, project selection, multi-criteria decision making, project sustainability and success criteria, MACBETH

Procedia PDF Downloads 40

Authors: Hasan Izhar Khan, Naiqiang Zhang, Hong Xu, Zhongliang Zhu, Dongfang Jiang

Abstract:

Inconel 625 is a nickel-based alloy having outstanding corrosion resistance and developed for use at service temperatures ranging from cryogenic to 980°C. It got a wide range of applications in nuclear, petrochemical, chemical, marine, aeronautical, and aerospace industries. Currently, it is one of the candidate materials to be used as a structural material in ultra-supercritical (USC) power plants. In the high-temperature corrosive medium environment, metallic materials are susceptible to corrosion fatigue (CF). CF is an interaction between cyclic stress and corrosive medium environment that acts on a susceptible material and results in initiation and propagation of cracks. For the application of Inconel 625 as a structural material in USC power plants, CF behavior must be evaluated in steam and supercritical water (SCW) environment. Fatigue crack growth rate (FCGR) curves obtained from CF experiments are required to predict residual life of metallic materials used in power plants. In this study, FCGR tests of Inconel 625 were obtained by using compact tension specimen at 550-650 °C in steam (8 MPa) and SCW (25 MPa). The dissolved oxygen level was kept constant at 8000 ppb for the test conducted in steam and SCW. The tests were performed under sine wave loading waveform, 1 Hz loading frequency, stress ratio of 0.6 and maximum stress intensity factor of 32 MPa√m. Crack growth rate (CGR) was detected by using direct current potential drop technique. Results showed that CGR increased with an increase in temperature in the tested environmental conditions. The mechanism concerning the influence of temperature on FCGR are further discussed.

Keywords: corrosion fatigue, crack growth rate, nickel-based alloy, temperature

Procedia PDF Downloads 109

Authors: Ahmed F. Ghanem, Marwa I. Wahba, Asmaa N. El-Dein, Mohamed A. EL-Raey, Ghada E.A. Awad

Abstract:

Numerous attempts are being performed in order to formulate suitable packaging materials for meat products. However, to the best of our knowledge, the incorporation of free hibiscus extract or its microcapsules in the pure polyvinyl alcohol (PVA) matrix as packaging materials for meats is seldom reported. Therefore, this study aims at protection of the aqueous crude extract of hibiscus flowers utilizing spry drying encapsulation technique. Fourier transform infrared (FTIR), scanning electron microscope (SEM), and zetasizer results confirmed the successful formation of assembled capsules via strong interactions, spherical rough microparticles, and ~ 235 nm of particle size, respectively. Also, the obtained microcapsules enjoy high thermal stability, unlike the free extract. Then, the obtained spray-dried particles were incorporated into the casting solution of the pure PVA film with a concentration 10 wt. %. The segregated free-standing composite films were investigated, compared to the neat matrix, with several characterization techniques such as FTIR, SEM, thermal gravimetric analysis (TGA), mechanical tester, contact angle, water vapor permeability, and oxygen transmission. The results demonstrated variations in the physicochemical properties of the PVA film after the inclusion of the free and the extract microcapsules. Moreover, biological studies emphasized the biocidal potential of the hybrid films against microorganisms contaminating the meat. Specifically, the microcapsules imparted not only antimicrobial but also antioxidant activities to PVA. Application of the prepared films on the real meat samples displayed low bacterial growth with a slight increase in the pH over the storage time up to 10 days at 4 oC which further proved the meat safety. Moreover, the colors of the films did not significantly changed except after 21 days indicating the spoilage of the meat samples. No doubt, the dual-functional of prepared composite films pave the way towards combined active/smart food packaging applications. This would play a vital role in the food hygiene, including also quality control and assurance.

Keywords: PVA, hibiscus, extraction, encapsulation, active packaging, smart and intelligent packaging, meat spoilage

Procedia PDF Downloads 59

Authors: G. Henini, Y. Laidani, F. Souahi, A. Labbaci, S. Hanini

Abstract:

Environmental contamination is a major problem being faced by the society today. Industrial, agricultural, and domestic wastes, due to the rapid development in the technology, are discharged in the several receivers. Generally, this discharge is directed to the nearest water sources such as rivers, lakes, and seas. While the rates of development and waste production are not likely to diminish, efforts to control and dispose of wastes are appropriately rising. Wastewaters from textile industries represent a serious problem all over the world. They contain different types of synthetic dyes which are known to be a major source of environmental pollution in terms of both the volume of dye discharged and the effluent composition. From an environmental point of view, the removal of synthetic dyes is of great concern. Among several chemical and physical methods, adsorption is a promising technique due to the ease of use and low cost compared to other applications in the process of discoloration, especially if the adsorbent is inexpensive and readily available. The focus of the present study was to assess the potentiality of Brahea edulis (BE) for the removal of synthetic dye Yellow bemacid (YB) from aqueous solutions. The results obtained here may transfer to other dyes with a similar chemical structure. Biosorption studies were carried out under various parameters such as mass adsorbent particle, pH, contact time, initial dye concentration, and temperature. The biosorption kinetic data of the material (BE) was tested by the pseudo first-order and the pseudo-second-order kinetic models. Thermodynamic parameters including the Gibbs free energy ΔG, enthalpy ΔH, and entropy ΔS have revealed that the adsorption of YB on the BE is feasible, spontaneous, and endothermic. The equilibrium data were analyzed by using Langmuir, Freundlich, Elovich, and Temkin isotherm models. The experimental results show that the percentage of biosorption increases with an increase in the biosorbent mass (0.25 g: 12 mg/g; 1.5 g: 47.44 mg/g). The maximum biosorption occurred at around pH value of 2 for the YB. The equilibrium uptake was increased with an increase in the initial dye concentration in solution (C_o = 120 mg/l; q = 35.97 mg/g). Biosorption kinetic data were properly fitted with the pseudo-second-order kinetic model. The best fit was obtained by the Langmuir model with high correlation coefficient (R² > 0.998) and a maximum monolayer adsorption capacity of 35.97 mg/g for YB.

Keywords: adsorption, Brahea edulis, isotherm, yellow Bemacid

Procedia PDF Downloads 156

Authors: Akram Khelaifia, Salah Guettala, Nesreddine Djafar Henni, Rachid Chebili

Abstract:

Recent seismic events have underscored the significant influence of masonry infill walls on the resilience of structures. The irregular positioning of these walls exacerbates their adverse effects, resulting in substantial material and human losses. Research and post-earthquake evaluations emphasize the necessity of considering infill walls in both the design and assessment phases. This study delves into the presence of soft stories in reinforced concrete structures with infill walls. Employing an approximate method relying on pushover analysis results, fiber-section-based macro-modeling is utilized to simulate the behavior of infill walls. The findings shed light on the presence of soft first stories, revealing a notable 240% enhancement in resistance for weak column—strong beam-designed frames due to infill walls. Conversely, the effect is more moderate at 38% for strong column—weak beam-designed frames. Interestingly, the uniform distribution of infill walls throughout the structure's height does not influence soft-story emergence in the same seismic zone, irrespective of column-beam strength. In regions with low seismic intensity, infill walls dissipate energy, resulting in consistent seismic behavior regardless of column configuration. Despite column strength, structures with open-ground stories remain vulnerable to soft first-story emergence, underscoring the crucial role of infill walls in reinforced concrete structural design.

Keywords: masonry infill walls, soft Storey, pushover analysis, fiber section, macro-modeling

Procedia PDF Downloads 31

Authors: Lee Cahaner, Nissim Leon

Abstract:

The segregation of populations is one of the main axes in the research of urban geography, which refers to the spatial and functional relationships between settlements. In Israel, this phenomenon has its unique expression in the spatial processes concerning the ultra-orthodox population. This population holds a set of interactions within itself as well as with the non-orthodox surrounding population because of historical and contemporary motivations on its which strength depends on its homogeneousness and separation. Its demographic growth rate and the internal social processes that the ultra-orthodox society undergoes create a new image of the ultra-orthodox concentration and its location in the Israeli space. The goals of the present study have also been defined with the express intention of filling the scholarly vacuum noted above: firstly, to discuss the development of the Israeli ultra-Orthodox sector’s hierarchical and spatial structure as of 2015, in light of the principles and mechanisms that guide it and vis-à-vis the general population’s hierarchical locality system; secondly, to map Israel’s ultra-Orthodox population, with attention to its physical boundaries, its subdivisions (Hassidic, Lithuanian, Sephardic) and the geographical and demographic processes that have characterized it in recent years; and thirdly, to shed light on the interactions between ultra-Orthodox localities via several different parameters, e.g. migration, education, transportation, employment, consumerism and community services. In order to understand the changes in ultra-Orthodox geographic distribution and the social processes that these changes have generated, a number of research activities were conducted during the course of this study− notably, gathering and assembling material from earlier academic studies, newspaper advertisements, state and private archives; in-depth interviews with major figures in the ultra-Orthodox community and others who come into contact with it; tours of the core areas of ultra-Orthodox settlement; and gathering quantitative and qualitative data from the statistical reports of governmental and other bodies. In addition, a multi-participant (2400-respondent) quantitative survey was conducted among residents of the new ultra-Orthodox cities, designed to elucidate the attributes and spatial attitudes of the residents− as a means of tracing and understanding this new settlement pattern within ultra-Orthodox space. A major portion of the quantitative and qualitative material was processed to form a system of maps that visually describe the distribution of Israel’s ultra-Orthodox population.

Keywords: migration, new cities, segregation, ultra-orthodox

Procedia PDF Downloads 377

Authors: Kamil Dydek, Anna Boczkowska, Paulina Latko-Duralek, Rafal Kozera, Michal Salacinski

Abstract:

In recent years there has been increasing interest in many industries, such as the aviation, automotive, and military industries, in Carbon Fibre Reinforced Polymers (CFRP). This is because of the excellent properties of CFRP, which are characterized by very high strength and stiffness in relation to their mass, low density (almost twice as low as aluminum and more than five times as low as steel), and corrosion resistance. However, they do not have sufficient electrical conductivity, which is required in some applications. Therefore, work is underway to improve their electrical conductivity, for example, by incorporating carbon nanotubes (CNTs) into the CFRP structure. CNTs possess excellent properties, such as high electrical conductivity, high aspect ratio, high Young’s modulus, and high tensile strength. An idea developed by our team is a modification of CFRP by the use of thermoplastic nonwovens containing CNTs. Nanocomposite fibers were made from three different masterbatches differing in the content of multi-wall carbon nanotubes, and then nonwovens that differed in areal weight were produced using a thermo-press. The out of autoclave method was used to fabricate the laminates from commercial carbon-epoxy prepreg dedicated to aviation applications - one without the nonwovens (reference) and five containing nonwovens placed between each prepreg layer. The volume of electrical conductivity of the manufactured laminates was measured in three directions. In order to investigate the adhesion between carbon fibers and nonwovens, the microstructure of the produced laminates was observed. The mechanical properties of the CFRP composites were measured in a short-beam shear test. In addition, the influence of thermoplastic nonwovens on the thermos-mechanical properties of laminates was analyzed by Dynamic Mechanical Analysis. The studies were carried out within grant no. DOB-1-3/1/PS/2014 financed by the National Centre for Research and Development in Poland.

Keywords: CFRP, thermoplastic nonwovens, carbon nanotubes, electrical conductivity

Procedia PDF Downloads 104

Authors: Long Long Chen, Xinwei Liao, Shanfa Tang, Shaojing Jiang, Ruijia Tang, Rui Wang, Shu Yun Feng, Si Yao Wang

Abstract:

Tight oil reservoirs have poor physical properties, insufficient formation energy, and low natural productivity; it is necessary to effectively improve their crude oil recovery. CO₂ flooding is an important technical means to enhance oil recovery and achieve effective CO₂ storage in tight oil reservoirs, but its heterogeneity is strong, which makes CO₂ flooding prone to gas channeling and poor recovery. Aiming at the problem of gas injection channeling, combined with the excellent performance of low interfacial tension viscoelastic fluid (GOBTK), the research on CO₂-low interfacial tension viscoelastic fluid synergistic oil displacement in tight reservoirs was carried out, and the synergy of CO₂ and low interfacial tension viscoelastic fluid was discussed. Oil displacement mechanism. Experiments show that GOBTK has good injectability in tight oil reservoirs (Kg=0.141～0.793mD); CO₂-0.4% GOBTK synergistic flooding can improve the recovery factor of low permeability layers (31.41%) under heterogeneous (gradient difference of 10) conditions the) effect is better than that of CO₂ flooding (0.56%) and 0.4% GOBT-water flooding (20.99%); CO₂-GOBT synergistic oil displacement mechanism includes: 1) The formation of CO₂ foam increases the flow resistance of viscoelastic fluid, forcing the displacement fluid to flow 2) GOBTK can emulsify and disperse residual oil into small oil droplets, and smoothly pass through narrow pores to produce; 3) CO₂ dissolved in GOBTK synergistically enhances the water wettability of the core, and the use of viscosity Elastomeric fluid injection and stripping of residual oil; 4) CO₂-GOBTK synergy superimposes multiple mechanisms, effectively improving the swept volume and oil washing efficiency of the injected fluid to the reservoir.

Keywords: tight oil reservoir, CO₂ flooding, low interfacial tension viscoelastic fluid flooding, synergistic oil displacement, EOR mechanism

Procedia PDF Downloads 152

Authors: Rachel Shukrun, Szilvia Baron, Victoria Fidel, Anna Shusterman, Osnat Sher, Netanya Kollender, Dror Levin, Yair Peled, Yair Gortzak, Yoav Ben-Shahar, Revital Caspi, Sagi Gordon, Michal Manisterski, Ronit Elhasid

Abstract:

Ewing sarcoma (EWS) is a highly aggressive cancer with a survival rate of 70–80% for patients with localized disease and under 30% for those with metastatic disease. Tumor-infiltrating neutrophils (TIN) can generate extracellular net-like DNA structures known as neutrophil extracellular traps (NETs). However, little is known about the presence and prognostic significance of tumor-infiltrating NETs in EWS. Herein, we investigated 46 patients diagnosed with EWS and treated in the Tel Aviv Medical Center between 2010 and 2021. TINs and NETs were identified in diagnostic biopsies of EWS by immunofluorescent. In addition, NETs were investigated in neutrophils isolated from peripheral blood samples of EWS patients at diagnosis and following neoadjuvant chemotherapy. The relationships between the presence of TINs and NETs, pathological and clinical features, and outcomes were analyzed. Our results demonstrate that TIN and NETs at diagnosis were higher in EWS patients with metastatic disease compared to those with local disease. High NETs formation at diagnosis predicted poor response to neo-adjuvant chemotherapy, relapse, and death from disease (P < .05). NETs formation in peripheral blood samples at diagnosis was significantly elevated among patients with EWS compared to pediatric controls and decreased significantly following neoadjuvant chemotherapy. In conclusion, NETs formation seems to have a role in the EWS immune microenvironment. Their presence can refine risk stratification, predict chemotherapy resistance and survival, and serve as a therapeutic target in patients with EWS.

Keywords: Ewing sarcoma, tumor microenvironment, neutrophil, neutrophil extracellular traps (NETs), prognosis

Procedia PDF Downloads 37

Authors: Zeinab Yazdanfar, Dilan Robert, Daniel Lester, S. Setunge

Abstract:

Scour has been identified as the most common threat to bridge stability worldwide. Traditionally, scour around bridge piers is calculated using the empirical approaches that have considerable limitations and are difficult to generalize. The multi-physic nature of scouring which involves turbulent flow, soil mechanics and solid-fluid interactions cannot be captured by simple empirical equations developed based on limited laboratory data. These limitations can be overcome by direct numerical modeling of coupled hydro-mechanical scour process that provides a robust prediction of bridge scour and valuable insights into the scour process. Several numerical models have been proposed in the literature for bridge scour estimation including Eulerian flow models and coupled Euler-Lagrange models incorporating an empirical sediment transport description. However, the contact forces between particles and the flow-particle interaction haven’t been taken into consideration. Incorporating collisional and frictional forces between soil particles as well as the effect of flow-driven forces on particles will facilitate accurate modeling of the complex nature of scour. In this study, a coupled Computational Fluid Dynamics and Discrete Element Model (CFD-DEM) has been developed to simulate the scour process that directly models the hydro-mechanical interactions between the sediment particles and the flowing water. This approach obviates the need for an empirical description as the fundamental fluid-particle, and particle-particle interactions are fully resolved. The sediment bed is simulated as a dense pack of particles and the frictional and collisional forces between particles are calculated, whilst the turbulent fluid flow is modeled using a Reynolds Averaged Navier Stocks (RANS) approach. The CFD-DEM model is validated against experimental data in order to assess the reliability of the CFD-DEM model. The modeling results reveal the criticality of particle impact on the assessment of scour depth which, to the authors’ best knowledge, hasn’t been considered in previous studies. The results of this study open new perspectives to the scour depth and time assessment which is the key to manage the failure risk of bridge infrastructures.

Keywords: bridge scour, discrete element method, CFD-DEM model, multi-phase model

Procedia PDF Downloads 107

Authors: Sin Ying Tan, Mohammed Alloghani, A. J. Aljaaf, Abir Hussain, Jamila Mustafina

Abstract:

Industry 4.0 is a term frequently used to describe the new upcoming industry era. Higher education institutions aim to prepare students to fulfil the future industry needs. Advancement of digital technology has paved the way for the evolution of education and technology. Evolution of education has proven its conservative nature and a high level of resistance to changes and transformation. The gap between the industry's needs and competencies offered generally by education is revealing the increasing need to find new educational models to face the future. The aim of this study was to identify the main issues faced by both universities and students in preparing the future workforce. From December 2018 to April 2019, a regional qualitative study was undertaken in Liverpool, United Kingdom (UK). Interviews were conducted with employers, faculty members and undergraduate students, and the results were analyzed using the open coding method. Four main issues had been identified, which are the characteristics of the future workforce, student's readiness to work, expectations on different roles played at the tertiary education level and awareness of the latest trends. The finding of this paper concluded that the employers and academic practitioners agree that their expectations on each other’s roles are different and in order to face the rapidly changing technology era, students should not only have the right skills, but they should also have the right attitude in learning. Therefore, the authors address this issue by proposing a learning framework known as 'ASK SUMA' framework as a guideline to support the students, academicians and employers in meeting the needs of 'Industry 4.0'. Furthermore, this technology era requires the employers, academic practitioners and students to work together in order to face the upcoming challenges and fast-changing technologies. It is also suggested that an interactive system should be provided as a platform to support the three different parties to play their roles.

Keywords: attitude, expectations, industry needs, knowledge, skills

Procedia PDF Downloads 100

Authors: Faris Tarlochan, Siva Mahesh Tangutooru

Abstract:

Lateral Geniculate Nucleus (LGN) is the relay center in the visual pathway as it receives most of the input information from retinal ganglion cells (RGC) and sends to visual cortex. Low threshold calcium currents (IT) at the membrane are the unique indicator to characterize this firing functionality of the LGN neurons gained by the RGC input. According to the LGN functional requirements such as functional mapping of RGC to LGN, the morphologies of the LGN neurons were developed. During the neurological disorders like glaucoma, the mapping between RGC and LGN is disconnected and hence stimulating LGN electrically using deep brain electrodes can restore the functionalities of LGN. A computational model was developed for simulating the LGN neurons with three predominant morphologies, each representing different functional mapping of RGC to LGN. The firings of action potentials at LGN neuron due to IT were characterized by varying the stimulation parameters, morphological parameters and orientation. A wide range of stimulation parameters (stimulus amplitude, duration and frequency) represents the various strengths of the electrical stimulation with different morphological parameters (soma size, dendrites size and structure). The orientation (0-1800) of LGN neuron with respect to the stimulating electrode represents the angle at which the extracellular deep brain stimulation towards LGN neuron is performed. A reduced dendrite structure was used in the model using Bush–Sejnowski algorithm to decrease the computational time while conserving its input resistance and total surface area. The major finding is that an input potential of 0.4 V is required to produce the action potential in the LGN neuron which is placed at 100 µm distance from the electrode. From this study, it can be concluded that the neuroprostheses under design would need to consider the capability of inducing at least 0.4V to produce action potentials in LGN.

Keywords: Lateral Geniculate Nucleus, visual cortex, finite element, glaucoma, neuroprostheses

Procedia PDF Downloads 256

Authors: Srinivasa Reddy Mallampati, Min Hee Park, Soo Mim Cho, Sung Hyeon Yoon

Abstract:

One of the issues of End of Life Vehicles (ELVs) recycling promotion is technology for the appropriate treatment of automotive shredder residue (ASR). Owing to its high heterogeneity and variable composition (plastic (23–41%), rubber/elastomers (9–21%), metals (6–13%), glass (10–20%) and dust (soil/sand) etc.), ASR can be classified as ‘hazardous waste’, on the basis of the presence of heavy metals (HMs), PCBs, BFRs, mineral oils, etc. Considering their relevant concentrations, these metals and plastics should be properly recovered for recycling purposes before ASR residues are disposed of. Brominated flame retardant additives in ABS/HIPS and PVC may generate dioxins and furans at elevated temperatures. Moreover, these BFRs additives present in plastic materials may leach into the environment during landfilling operations. ASR thermal process removes some of the organic material but concentrates, the heavy metals and POPs present in the ASR residues. In the present study, Fe/Ca/CaO nanoparticle assisted ozone treatment has been found to selectively hydrophilize the surface of ABS/HIPS and PVC plastics, enhancing its wettability and thereby promoting its separation from ASR plastics by means of froth flotation. The water contact angles, of ABS/HIPS and PVC decreased, about 18.7°, 18.3°, and 17.9° in ASR respectively. Under froth flotation conditions at 50 rpm, about 99.5% and 99.5% of HIPS in ASR samples sank, resulting in a purity of 98% and 99%. Furthermore, at 150 rpm a 100% PVC separation in the settled fraction, with 98% of purity in ASR, respectively. Total recovery of non-ABS/HIPS and PVC plastics reached nearly 100% in the floating fraction. This process improved the quality of recycled ASR plastics by removing surface contaminants or impurities. Further, a hybrid ball-milling and with Fe/Ca/CaO nanoparticle froth flotation process was established for the recovery of HMs from ASR. After ball-milling with Fe/Ca/CaO nanoparticle additives, the flotation efficiency increased to about 55 wt% and the HMs recovery were also increased about 90% for the 0.25 mm size fractions of ASR. Coating with Fe/Ca/CaO nanoparticles associated with subsequent microbubble froth flotation allowed the air bubbles to attach firmly on the HMs. SEM–EDS maps showed that the amounts of HMs were significant on the surface of the floating ASR fraction. This result, along with the low HM concentration in the settled fraction, was confirmed by elemental spectra and semi-quantitative SEM–EDS analysis. Developed hybrid preferential hazardous plastics and metals separation process from ASR is a simple, highly efficient, and sustainable procedure.

Keywords: end of life vehicles shredder residue, hazardous plastics, nanoparticle froth flotation, separation process

Procedia PDF Downloads 258

Authors: Soheil Heydari, Ailar Hajimohammadi, Nasser Khalili

Abstract:

Polystyrene, being made from a monomer called styrene, is a rigid and easy-to mould polymer that is widely used for many applications, from foam packaging to disposable containers. Considering that the degradation of waste polystyrene takes up to 500 years, there is an urgent need for a sustainable application for waste polystyrene. This study evaluates the application of waste polystyrene as an asphalt modifier. The inclusion of waste plastics in asphalt is either practised by the dry process or the wet process. In the dry process, plastics are added straight into the asphalt mixture and in the wet process, they are mixed and digested into bitumen. In this article, polystyrene was used as an asphalt modifier in a dry process. However, the mixing process is precisely designed to make sure that the polymer is melted and modified in the binder. It was expected that, due to the rigidity of polystyrene, it will have positive effects on the permanent deformation of the asphalt mixture. Therefore, different mixtures were manufactured with different contents of polystyrene and Marshall specimens were manufactured, and dynamic creep tests were conducted to evaluate the permanent deformation of the modification. This is a commonly repeated loading test conducted at different stress levels and temperatures. Loading cycles are applied to the AC specimen until failure occurs; with the amount of deformation constantly recorded the cumulative, permanent strain is determined and reported as a function of the number of cycles. Also, to our best knowledge, hybrid mixes of polystyrene with crumb rubber and low-density polyethylene were made and compared with a polystyrene-modified mixture. The test results of this study showed that the hybrid mix of polystyrene and low-density polyethylene has the highest resistance against permanent deformation. However, the polystyrene-modified mixture outperformed the hybrid mix of polystyrene and crumb rubber, and both demonstrated way lower permanent deformation than the unmodified specimen.

Keywords: permanent deformation, waste plastics, polystyrene, hybrid plastics, hybrid mix, hybrid modification, dry process

Procedia PDF Downloads 66

Authors: Tao Yang, Yongli Zhao

Abstract:

Low-temperature cracking is one of the major challenges for asphalt pavement in the cold region. Fracture energy could determine from various test methods, which is a commonly used parameter to evaluate the low-temperature cracking resistance of asphalt mixture. However, the feasibility of evaluating the low-temperature cracking performance of asphalt mixture using fracture energy is not investigated comprehensively. This paper aims to verify whether fracture energy is an appropriate parameter to evaluate the low-temperature cracking performance. To achieve this goal, this paper compared the test results of thermal stress restrained specimen test (TSRST) and semi-circular bending test (SCB) of asphalt mixture with different types of aggregate, TSRST and indirect tensile test (IDT) of asphalt mixture with different additives, and single-edge notched beam test (SENB) and TSRST of asphalt mixture with different asphalt. Finally, the correlation between in-suit cracking performance and fracture energy was surveyed. The experimental results showed the evaluation result of critical cracking temperature and fracture energy are not always consistent; the in-suit cracking performance is also not correlated well with fracture energy. These results indicated that it is not feasible to evaluate low-temperature performance by fracture energy. Then, the composition of fracture energy of TSRST, SCB, disk-shaped compact tension test (DCT), three-point bending test (3PB) and IDT was analyzed. The result showed: the area of thermal stress versus temperature curve is the multiple of fracture energy and could be used to represent fracture energy of TSRST, as the multiple is nearly equal among different asphalt mixtures for a specific specimen; the fracture energy, determined from TSRST, SCB, DCT, 3PB, SENB and IDT, is mainly the surface energy that forms the fracture face; fracture energy is inappropriate to evaluate the low-temperature cracking performance of asphalt mixture, as the relaxation/viscous performance is not considered; if the fracture energy was used, it is recommended to combine this parameter with an index characterizing the relaxation or creep performance of asphalt mixture.

Keywords: asphalt pavement, cold region, critical cracking temperature, fracture energy, low-temperature cracking

Procedia PDF Downloads 156

Authors: Anastasios Ntousas

Abstract:

The purpose of the following paper is to analyze the relationship between the lexical quality and the self-teaching hypothesis and their impact on the reading ability. The following questions emerged, is there a correlation between the effective reading experience that the lexical quality hypothesis proposes and the self-teaching hypothesis, would the ability to read by analogy facilitate and create stable, synchronized four-word representational, and would word morphological knowledge be a possible extension of the self-teaching hypothesis. The lexical quality hypothesis speculates that words include four representational attributes, phonology, orthography, morpho-syntax, and meaning. Those four-word representations work together to make word reading an effective task. A possible lack of knowledge in one of the representations might disrupt reading comprehension. The degree that the four-word features connect together makes high and low lexical word quality representations. When the four-word representational attributes connect together effectively, readers have a high lexical quality of words; however, when they hardly have a strong connection with each other, readers have a low lexical quality of words. Furthermore, the self-teaching hypothesis proposes that phonological recoding enables printed word learning. Phonological knowledge and reading experience facilitate the acquisition and consolidation of specific-word orthographies. The reading experience is related to strong reading comprehension. The more readers have contact with texts, the better readers they become. Therefore, their phonological knowledge, as the self-teaching hypothesis suggests, might have a facilitative impact on the consolidation of the orthographical, morphological-syntax and meaning representations of unknown words. The phonology of known words might activate effectively the rest of the representational features of words. Readers use their existing phonological knowledge of similarly spelt words to pronounce unknown words; a possible transference of this ability to read by analogy will appear with readers’ morphological knowledge. Morphemes might facilitate readers’ ability to pronounce and spell new unknown words in which they do not have lexical access. Readers will encounter unknown words with similarly phonemes and morphemes but with different meanings. Knowledge of phonology and morphology might support and increase reading comprehension. There was a careful selection, discussion of theoretical material and comparison of the two existing theories. Evidence shows that morphological knowledge improves reading ability and comprehension, so morphological knowledge might be a possible extension of the self-teaching hypothesis, the fundamental skill to read by analogy can be implemented to the consolidation of word – specific orthographies via readers’ morphological knowledge, and there is a positive correlation between effective reading experience and self-teaching hypothesis.

Keywords: morphology, orthography, reading ability, reading comprehension

Procedia PDF Downloads 96

Authors: Thanusha D. Abeywickrama, Inoka C. Perera, Genji Kurisu

Abstract:

Tuberculosis, considered being as the ninth leading cause of death worldwide, cause from a single infectious agent M. tuberculosis and the drug resistance nature of this bacterium is a continuing threat to the world. Therefore TB preventing treatment is expanding, where this study designed to analyze the regulatory mechanism of GntR transcriptional regulator gene Rv0792c, which lie between several genes codes for some hypothetical proteins, a monooxygenase and an oxidoreductase. The gene encoding Rv0792c was cloned into pET28a and expressed protein was purified to near homogeneity by Nickel affinity chromatography. It was previously reported that the protein binds within the intergenic region (BS region) between Rv0792c gene and monooxygenase (Rv0793). This resulted in binding of three protein molecules with the BS region suggesting tight control of monooxygenase as well as its own gene. Since monooxygenase plays a key role in metabolism, this gene may have a global regulatory role. The natural ligand for this regulator is still under investigation. In relation to the Rv0792 protein structure, a Circular Dichroism (CD) spectrum was carried out to determine its secondary structure elements. Percentage-wise, 17.4% Helix, 21.8% Antiparallel, 5.1% Parallel, 12.3% turn and 43.5% other were revealed from CD spectrum data under room temperature. Differential Scanning Calorimetry (DSC) was conducted to assess the thermal stability of Rv0792, which the melting temperature of protein is 57.2 ± 0.6 °C. The graph of heat capacity (Cp) versus temperature for the best fit was obtained for non-two-state model, which concludes the folding of Rv0792 protein occurs through stable intermediates. Peak area (∆HCal ) and Peak shape (∆HVant ) was calculated from the graph and ∆HCal / ∆HVant was close to 0.5, suggesting dimeric nature of the protein.

Keywords: CD spectrum, DSC analysis, GntR transcriptional regulator, protein structure

Procedia PDF Downloads 201

Authors: Zhiguo Yang, Xiangan Yue, Minglu Shao, Yue Yang, Rongjie Yan

Abstract:

It is difficult to realize deep profile control because of the small pore-throats and easy water channeling in low-permeability heterogeneous reservoir, and the traditional polymer microspheres have the contradiction between injection and plugging. In order to solve this contradiction, the controllable self-aggregating colloidal particles (CSA) containing amide groups on the surface of microspheres was prepared based on emulsion polymerization of styrene and acrylamide. The dispersed solution of CSA colloidal particles, whose particle size is much smaller than the diameter of pore-throats, was injected into the reservoir. When the microspheres migrated to the deep part of reservoir, , these CSA colloidal particles could automatically self-aggregate into large particle clusters under the action of the shielding agent and the control agent, so as to realize the plugging of the water channels. In this paper, the morphology, temperature resistance and self-aggregation properties of CSA microspheres were studied by transmission electron microscopy (TEM) and bottle test. The results showed that CSA microspheres exhibited heterogeneous core-shell structure, good dispersion, and outstanding thermal stability. The microspheres remain regular and uniform spheres at 100℃ after aging for 35 days. With the increase of the concentration of the cations, the self-aggregation time of CSA was gradually shortened, and the influence of bivalent cations was greater than that of monovalent cations. Core flooding experiments showed that CSA polymer microspheres have good injection properties, CSA particle clusters can effective plug the water channels and migrate to the deep part of the reservoir for profile control.

Keywords: heterogeneous reservoir, deep profile control, emulsion polymerization, colloidal particles, plugging characteristic

Procedia PDF Downloads 196

Authors: Susumu Fukita, Hiromi Kawasaki, Satoko Yamasaki, Kotomi Yamashita, Tomoko Iki

Abstract:

The increase in the number of workers with mental health problems has become an issue. Many workers work in small- and medium-sized enterprises, which often support local employment and economy, especially in underpopulated mountainous areas. It is important for managers to take mental health measures for employees since there is no budget to hire health staff in small- and medium-sized enterprises. It is necessary to understand the manager's attitude toward the mental health of employees and to publicly support the manager in promoting mental health measures for employees. The purpose of this study was to study the awareness of managers of small- and medium-sized enterprises regarding the mental health of employees and to consider support for managers to take measures for the mental health of employees. Semi-structured interviews were conducted with six managers of small- and medium-sized enterprises in underpopulated mountainous areas in November 2019. Managers were asked about their awareness of the mental health of their employees. Qualitative descriptive analysis was used, and subcategories and categories were extracted. Four categories emerged. Regarding the mental health of employees, the managers acknowledged that if the appearance and behavior of the employees do not interfere with their lives, the manager judges that the employees’ mental health is normal. It was also found that the managers acknowledged that there is a comfortable working environment due to the characteristics of the underpopulated mountainous area. On the other hand, the managers acknowledged that employees are dissatisfied with salaries and management systems. In addition, it was found the manager acknowledged that some employees retire due to mental health problems. Although managers recognized that employees may be dissatisfied with salaries, they also recognized that there was a comfortable working environment due to the characteristics of the areas, with good interpersonal relationships. Economic challenges are difficult to solve in underpopulated mountainous areas. It is useful to consider measures that take advantage of the characteristics of the areas where it is easy to work because of good relations with each other, for example, to create a family-like workplace culture where managers and employees can engage in daily conversation. The managers judged that the employees were in good health if there was no interference with their lives. However, it is too late to take measures at the stage when it becomes an obstacle to life. Therefore, it is necessary to provide training for managers to learn observation techniques by which they quickly notice changes in the situation of employees and give appropriate responses; and to set up a contact point for managers to consult. Local governments should actively provide public support such as training for managers and establishing consultation desks to maintain valuable employment and local economics in underpopulated mountainous areas.

Keywords: employer, mental health, small- and medium- sized enterprises, underpopulated areas

Procedia PDF Downloads 118

Authors: Magdalena Kowalska, Weronika Rupik

Abstract:

The pancreas is an important organ present in all vertebrate species. It contains two different tissues, exocrine and endocrine, that act as two glands in one. The development and differentiation of the pancreas in reptiles is poorly known in comparison to other vertebrates. Therefore, the aim of this study was to investigate the particular steps concerning the differentiation of the pancreas in the grass snake (Natrix natrix) embryos. For this, histological methods (including hematoxylin and eosin, and Heidenhain's AZAN staining), transmission electron microscopy and three-dimensional (3D) reconstructions from serial paraffin sections were used. The results of this study indicated that the first step of pancreas development in Natrix was the connection of the two pancreatic buds: dorsal and ventral one. Then, duct walls in both buds started to be remodeled from the multilayered to single-layered epithelium. This remodeling started in the dorsal bud and was simultaneously with the differentiation of the duct lumens which occurred by the cavition. During this process, the cells that had no contact with the mesenchyme underwent cell death named anoikis. These findings indicated that the walls of ducts in the embryonic pancreas of the grass snake were initially formed by the abundant principal and single endocrine cells. Later the basal and goblet cells differentiated. Among the endocrine cells, as the first the B and A cells differentiated, then the D and PP cells. The next step of the pancreatic development was the withdrawing of the endocrine cells from the duct walls to form the pancreatic islets. The endocrine cells and islets were found only in the dorsal part of the pancreas in Natrix embryos what is different than in other vertebrate species. The islets were formed mainly by the A cells. Simultaneously, with the differentiation of the endocrine pancreas, the acinar tissue started to differentiate. The source of the acinar cells were pancreatic ducts similar as in other vertebrates. The acini formation began at the proximal part of the pancreas and went towards the caudal direction. Differentiating pancreatic ducts developed into the branched system that can be divided into extralobular, intralobular, and intercalated ducts, similarly as in other vertebrate species. However, the pattern of branching was different. In conclusions, particular steps of the pancreas differentiation in the grass snake were different than in other vertebrates. It can be supposed that these differences are related to the specific topography of the snake’s internal organs and their taxonomy position. All specimens used in the study were captured according to the Polish regulations concerning the protection of wild species. Permission was granted by the Local Ethics Commission in Katowice (41/2010; 87/2015) and the Regional Directorate for Environmental Protection in Katowice (WPN.6401.257.2015.DC).

Keywords: embryogenesis, organogenesis, pancreas, Squamata

Procedia PDF Downloads 147

Authors: Suelen C. Lima, André C. de Oliveira, Rosemary A. Roque

Abstract:

Dengue is fatal arboviruses transmitted by the A. aegypti mosquito to more than 100 countries, for which the WHO estimates that 2.5 million people will be infected by these disease. The widespread of these diseases is due, among other factors, to the resistance that A. aegypti has to several commercial insecticides. On the other hand, natural products based on plants of the genus Piper (Piperaceae) are characterized by their insecticidal activities against mosquitoes. Piper longepetiolatum and Piper brachypetiolatum are species with wide distribution in the State of Amazonas. However, there is no investigation of phytochemical or biological of these plants against mosquitoes such as A. aegypti. The main of this study was to identify the chemical composition of the essential oil (EOs) from P. longepetiolatum and P. brachypetiolatum and to evaluate the biological activity against A. aegypti. The EOs were extracted by hydrodistillation from leaves (200 g) of P. longepetiolatum and P. brachypetiolatum and analyzed by GC-MS and GC-FID. The main compounds β-caryophyllene (99.9% of purity) and E-nerolidol (99.4% of purity) were purchased from Sigma-Aldrich® Brazil. The larvicidal activity of EOs (20 to 100 ppm), β-caryophyllene and E-nerolidol (10 to 50 ppm) was performed according to WHO protocol against A. aegypti larvae. The GC-MS and GC-FID analysis of EOs from P. longepetiolatum and P. brachypetiolatum indicated the majority presence of β-caryophyllene (35.42%) and E-nerolidol (49.79%), respectively. The results showed that all natural products presented larvicidal activity against A. aegypti. In this aspect, the OE from P. brachypetiolatum (LC50 of 15.51 ppm and LC90 of 22.79 ppm) was more active than the OE from P. longepetiolatum (LC50 of 47.17 ppm and LC90 of 69.60 ppm) (p < 0.05). Regarding of main compounds, E-nerolidol (LC50 of 9.50 ppm and LC90 of 23.89 ppm) showed higher larvicidal activity than the β-caryophyllene compound (LC50 of 79.00 ppm and LC90 of 230.91 ppm) (p < 0.05). The larvae treated with these natural products showed tremors and lethargic movements, suggesting that these natural products have neurotoxic action. These observations support studies to investigate the mechanism of action. This is the first record of the chemical composition and larvicidal activity of the EO from P. longepetiolatum and P. brachypetiolatum rich in β-caryophyllene and E-nerolidol against A. aegypti larvae.

Keywords: piperaceae, aedes, sesquiterpenes, biological control

Procedia PDF Downloads 46

Authors: Sireen Irsheid

Abstract:

Despite concerted efforts to improve education attainment with progress in recent years, student achievement and attainment remain among the most significant challenges for school districts across the United States. Many scholars have argued that students who do not complete high school do not drop out of school voluntarily but are ‘pushed out’ of schools through multiple mechanisms related to structural and socioeconomic barriers, behavioral health challenges, pedagogical practices, and administrative procedures. Extant literature has shown that living in historically disadvantaged neighborhoods or attending under-resourced schools exacerbates student-level risk factors for grade retention and school pushout. Most efforts to respond to the school pushout phenomenon have focused on individual characteristics of students, with relatively little attention to addressing these multiple system-level characteristics related to perpetuating inequities. This study is built on a growing body of social justice-oriented research concerned with the systemic influences that shape the experiences and mental health challenges of young people. Specifically, this study examined how young people who have been experiencing education inequities make meaning and navigate the structural factors related to neighborhood and school disinvestment and access to resources and supports, and their risk for school pushout. Furthermore, schools as political, cultural, and ideologically reproductive spaces often serve as sites of resistance and can support students who are impacted by educational inequity. Study findings provide education, neighborhood, school psychology, social work practice, and policy considerations.

Keywords: education policy, mental health, school prison nexus, school pushout, structural trauma

Procedia PDF Downloads 27

Authors: Sajjad Shojaeidoust, Mohsen Ghanbarzadeh, Abdolhamid Habibi

Abstract:

Exercise-induced bronchospasm (EIB) is a transitory condition of airflow obstruction that is associated with physical activities. It is noted that high ventilation can lead to an increase in the heat and reduce in the moisture in airways resistance of trachea. Also causes of pathophysiological mechanism are EIB. Accordingly, studying some parameters of pulmonary function (FVC, FEV1) among active people seems quintessential. The aim of this study was to analyze bronchospasm following the implementation of a program of maximum aerobic exercise in active men at Chamran University of Ahwaz. Method: In this quasi-experimental study, the population consisted of all students at Chamran University. Among from 55 participants, of which, 15 were randomly selected as the experimental group. In this study, the size of the maximum oxygen consumption was initially measured, and then, based on the maximum oxygen consumed, the active individuals were identified. After five minutes’ warm-up, Strand treadmill exercise test was taken (one session) and pulmonary parameters were measured at both pre- and post-tests (spirometer). After data normalization using KS and non-normality of the data, the Wilcoxon test was used to analyze the data. The significance level for all statistical surveys was considered p≤0/05. Results: The results showed that the ventilation factors and bronchospasm (FVC, FEV1) in the pre-test and post-test resulted in no significant difference among the active people (p≥0/05). Discussion and conclusion: Based on the results observed in this study, it appears that pulmonary indices in active individuals increased after aerobic test. The increase in this indicator in active people is due to increased volume and elasticity of the lungs as well. In other words, pulmonary index is affected by rib muscles. It is considered that progress over respiratory muscle strength and endurance has raised FEV1 in the active cases.

Keywords: aerobic active maximum, bronchospasm, pulmonary function, spirometer

Procedia PDF Downloads 261

Authors: Rukshika S Hewawasam, Sisira K. Weliwegamage, Sanath Rajapakse, Subramanium Sotheeswaran

Abstract:

Bio fuel is one of the emerging industries around the world due to arise of crisis in petroleum fuel. Fermentation is a cost effective and eco-friendly process in production of bio-fuel. So inventions in microbes, substrates, technologies in fermentation cause new modifications in fermentation. One major problem in microbial ethanol fermentation is the low resistance of conventional microorganisms to the high ethanol concentrations, which ultimately lead to decrease in the efficiency of the process. In the present investigation, an ethanol resistant bacterium was isolated from sap of Saccharum officinarum (sugar cane). The optimal cultural conditions such as pH, temperature, incubation period, and microbiological characteristics, morphological characteristics, biochemical characteristics, ethanol tolerance, sugar tolerance, growth curve assay were investigated. Isolated microorganism was tolerated to 18% (V/V) of ethanol concentration in the medium and 40% (V/V) glucose concentration in the medium. Biochemical characteristics have revealed as Gram negative, non-motile, negative for Indole test ,Methyl Red test, Voges- Proskauer`s test, Citrate Utilization test, and Urease test. Positive results for Oxidase test was shown by isolated bacterium. Sucrose, Glucose, Fructose, Maltose, Dextrose, Arabinose, Raffinose, Lactose, and Sachcharose can be utilized by this particular bacterium. It is a significant feature in effective fermentation. The fermentation process was carried out in glucose medium under optimum conditions; pH 4, temperature 30˚C, and incubated for 72 hours. Maximum ethanol production was recorded as 12.0±0.6% (V/V). Methanol was not detected in the final product of the fermentation process. This bacterium is especially useful in bio-fuel production due to high ethanol tolerance of this microorganism; it can be used to enhance the fermentation process over conventional microorganisms. Investigations are currently conducted on establishing the identity of the bacterium

Keywords: bacterium, bio-fuel, ethanol tolerance, fermentation

Procedia PDF Downloads 309