Search results for: structural strengthening

Authors: Naoual Boussoualim, Hayat Trabsa, Iman Krache, Lekhmici Arrar, Abderrahmane Baghiani

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Resistance to antibiotics has emerged following their widespread use; the important mechanism of beta-lactam resistance in bacteria is the production of beta-lactamase. In order to find new bioactive beta-lactamase inhibitors, this study investigated the inhibition effect of the extracts of Anchusa azurea (AA) on a beta-lactamase from Bacillus cereus. The extracts exerted inhibitory effects on beta-lactamase in a dose-dependent manner, the results showed that the crude extract (BrE) and the ethyl acetate extract (AcE) of Anchusa azurea showed a very high inhibitory activity at a concentration of 10 mg, the percentage of inhibition was between 58% and 68%. Not all extracts were as potent as the original inhibitors such as clavulanic acid, the isolation and the structural elucidation of the active constituents in these extracts will provide useful means in the development of beta -lactamase inhibitors.

Keywords: Anchusa azurea, natural product, resistance, antibiotics, beta-lactamase, inhibitors

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Authors: J. van Vuuren, D. J. van Vuuren, R. Muigai

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In recent times, South Africa has experienced extensive droughts that created the need for reliable small water reservoirs. These reservoirs have comparatively quick fabrication and installation times compared to market alternatives. An elevated water tank has inherent potential energy, resulting in that no additional water pumps are required to sustain water pressure at the outlet point – thus ensuring that, without electricity, a water source is available. The initial construction formwork and the complex geometric shape of concrete towers that requires casting can become time-consuming, rendering steel towers preferable. Reinforced concrete foundations, cast in advance, are required to be of sufficient strength. Thereafter, the prefabricated steel supporting structure and tank, which consist of steel panels, can be assembled and erected on site within a couple of days. Due to the time effectiveness of this system, it has become a popular solution to aid drought-stricken areas. These sites are normally in rural, schools or farmland areas. As these tanks can contain up to 2000kL (approximately 19.62MN) of water, combined with supporting lattice steel structures ranging between 5m and 30m in height, failure of one of the supporting members will result in system failure. Thus, there is a need to gain a comprehensive understanding of the operation conditions because of wind loadings on both the tank and the supporting structure. The aim of the research is to investigate the relationship between the theoretical wind loading on a lattice steel tower in combination with an elevated sectional steel tank, and the current wind loading codes, as applicable to South Africa. The research compares the respective design parameters (both theoretical and wind loading codes) whereby FEA analyses are conducted on the various design solutions. The currently available wind loading codes are not sufficient to design slender cantilever latticed steel towers that support elevated water storage tanks. Numerous factors in the design codes are not comprehensively considered when designing the system as these codes are dependent on various assumptions. Factors that require investigation for the study are; the wind loading angle to the face of the structure that will result in maximum load; the internal structural effects on models with different bracing patterns; the loading influence of the aspect ratio of the tank; and the clearance height of the tank on the structural members. Wind loads, as the variable that results in the highest failure rate of cantilevered lattice steel tower structures, require greater understanding. This study aims to contribute towards the design process of elevated steel tanks with lattice tower supporting structures.

Keywords: aspect ratio, bracing patterns, clearance height, elevated steel tanks, lattice steel tower, wind loads

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Authors: Tadaaki Tomiie, Hiroki Shinkawa

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The present study was aimed to examine the structure of children’s adaptation during school transition and to identify a commonality and dissimilarity at the elementary and junior high school. 1,983 students in the 6th grade and 2,051 students in the 7th grade were extracted by stratified two-stage random sampling and completed the ASSESS that evaluated the school adaptation from the view point of ‘general satisfaction’, ‘teachers’ support’, ‘friends’ support’, ‘anti-bullying relationship’, ‘prosocial skills’, and ‘academic adaptation’. The 7th graders tend to be worse adaptation than the 6th graders. A structural equation modeling showed the goodness of fit for each grades. Both models were very similar but the 7th graders’ model showed a lower coefficient at the pass from ‘teachers’ support’ to ‘friends’ support’. The role of ‘teachers’ support’ was decreased to keep a good relation in junior high school. We also discussed how we provide a continuous assistance for prevention of the 7th graders’ gap.

Keywords: school transition, social support, psychological adaptation, K-12

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Authors: Daniel Martin Fellows, Sean P. Walton, Jennifer Thompson, Oubay Hassan, Ella Quigley, Kevin Tinkham

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Fire performance is a crucial aspect to consider when designing cladding products, and testing this performance is extremely expensive. Appropriate use of numerical simulation of fire performance has the potential to reduce the total number of fire tests required when designing a product by eliminating poor-performing design ideas early in the design phase. Due to the complexity of fire and the large spectrum of failures it can cause, multi-disciplinary models are needed to capture the complex fire behavior and its structural effects on its surroundings. Working alongside Tata Steel U.K., the authors have focused on completing a coupled CFD-FEA simulation model suited to test Polyisocyanurate (PIR) based sandwich panel products to gain confidence before costly experimental standards testing. The sandwich panels are part of a thermally insulating façade system primarily for large non-domestic buildings. The work presented in this paper compares two coupling methodologies of a replicated physical experimental standards test LPS 1181-1, carried out by Tata Steel U.K. The two coupling methodologies that are considered within this research are; one-way and two-way. A one-way coupled analysis consists of importing thermal data from the CFD solver into the FEA solver. A two-way coupling analysis consists of continuously importing the updated changes in thermal data, due to the fire's behavior, to the FEA solver throughout the simulation. Likewise, the mechanical changes will also be updated back to the CFD solver to include geometric changes within the solution. For CFD calculations, a solver called Fire Dynamic Simulator (FDS) has been chosen due to its adapted numerical scheme to focus solely on fire problems. Validation of FDS applicability has been achieved in past benchmark cases. In addition, an FEA solver called ABAQUS has been chosen to model the structural response to the fire due to its crushable foam plasticity model, which can accurately model the compressibility of PIR foam. An open-source code called FDS-2-ABAQUS is used to couple the two solvers together, using several python modules to complete the process, including failure checks. The coupling methodologies and experimental data acquired from Tata Steel U.K are compared using several variables. The comparison data includes; gas temperatures, surface temperatures, and mechanical deformation of the panels. Conclusions are drawn, noting improvements to be made on the current coupling open-source code FDS-2-ABAQUS to make it more applicable to Tata Steel U.K sandwich panel products. Future directions for reducing the computational cost of the simulation are also considered.

Keywords: fire engineering, numerical coupling, sandwich panels, thermo fluids

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Authors: Raja Kannusamy

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The research focuses on the applicable technologies in the automobile industry and their effects on the productivity and annual revenue of the industry. A study has been conducted on 6 major automobile manufacturing industries represented in this research as M1, M2, M3, M4, M5 and M6. The results indicate that M1, which is a pioneer in technological applications, remains the market leader, followed by M5 & M2 taking the second and third positions, respectively. M3, M6 and M4 are the followers and are placed next in positions. It has also been observed that M1 and M2 have entered into an agreement to share the basic structural technologies and they maintain long-term and trusted relationships with their suppliers through the Keiretsu system. With technological giants such as Apple, Microsoft, Uber and Google entering the automobile industry in recent years, an upward trend is expected in the futuristic market with self-driving cars to dominate the automobile sector. To keep up with the market trend, it is essential for automobile manufacturers to understand the importance of developing technological capabilities and skills to be competitive in the marketplace.

Keywords: automobile manufacturing industries, competitiveness, performance improvement, technological applications

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Authors: K. Sowri Babu, P. Srinath, N. Rajeswara Rao, K. Venugopal Reddy

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The effect of gamma ray irradiation on morphology and optical properties of ZnO/Mesoporous silica (MPS) nanocomposite was studied. The ZnO/MPS nanocomposite was irradiated with gamma rays of doses 30, 60, and 90 kGy and dose-rate of irradiation was 0.15 kGy/hour. Irradiated samples are characterized with FE-SEM, FT-IR, UV-vis, and Photoluminescence (PL) spectrometers. SEM pictures showed that morphology changed from spherical to flake like morphology. UV-vis analysis showed that the band gap increased with increase of gamma ray irradiation dose. This enhancement of the band gap is assigned to the depletion of oxygen vacancies with irradiation. The intensity of PL peak decreased gradually with increase of gamma ray irradiation dose. The decrease in PL intensity is attributed to the decrease of oxygen vacancies at the interface due to poor interface and improper passivation between ZnO/MPS.

Keywords: ZnO nanoparticles, nanocomposites, mesoporous silica, photoluminescence

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Authors: Ying Sun, Ji-wu Wang

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The establishment of a city is the result of the accumulation of local historical and cultural heritage and the sublimation of settlements. Take history as a mirror, it’s known how the things rise and fall. Based on the perspective of history, the development of the ancient city of Wenzhou was combed, and the urban development history of Wenzhou in 2200 could be divided into seven stages. This paper mainly studies the four stages of germination, formation, initial development and tortuous development, explores the external and internal driving forces of urban development and the structural evolution of urban layout, and discusses how the ancient Wenzhou evolved from a remote town to an important coastal port city. This paper finds that the most important factors affecting the development of ancient cities in Wenzhou are war, policy and geographical environment, and then points out the importance of urban policies to the rise and fall of cities.

Keywords: ancient city development, history, Wenzhou city, city policy

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Authors: Areeg Shermaddo

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Solar updraft power plants (SUPP) provide a great potential for green and environmentally friendly renewable power generation. An up to 1000 m high chimney represents one of the major parts of each SUPP, which consist of the main shell structure and the stiffening rings. Including the nonlinear material behavior in a simulation of the chimney is computationally a demanding task. However, allowing the formation of cracking in concrete leads to a more economical design of the structure. In this work, an FE model of a SUPP is presented incorporating the nonlinear material behavior. The effect of wind loading intensity on the structural response is explored. Furthermore, the influence of the stiffness of the ring beams on the global behavior is as well investigated. The obtained results indicate that the minimum reinforcement is capable of carrying the tensile stresses provided that the ring beams are rather stiff.

Keywords: ABAQUS, nonlinear analysis, ring beams, SUPP

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Authors: Yangsu Kwon, Hyo-Gyoung Kwak

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Nonlinear tendon constitutive model for nonlinear analysis of pre-stressed concrete structures are presented. Since the post-cracking behavior of concrete structures, in which bonded reinforcements such as tendons and/or reinforcing steels are embedded, depends on many influencing factors(the tensile strength of concrete, anchorage length of reinforcements, concrete cover, and steel spacing) that are deeply related to the bond characteristics between concrete and reinforcements, consideration of the tension stiffening effect on the basis of the bond-slip mechanism is necessary to evaluate ultimate resisting capacity of structures. In this paper, an improved tendon model, which considering the slip effect between concrete and tendon, and effect of tension stiffening, is suggested. The validity of the proposed models is established by comparing between the analytical results and experimental results in pre-stressed concrete beams.

Keywords: bond-slip, prestressed concrete, tendon, ultimate strength

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Authors: Rolla Monib, Chris Ian Goodier, Alistair Gibb

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This paper aims to investigate decision support strategies in the EC sector to determine the most appropriate degree of modularization. This is achieved through three oil and gas (O&G) and two power plant case studies via semi-structured interviews (n=59 and n=27, respectively), analysis of project documents, and case study-specific semi-structured validation interviews (n=12 and n=8). New terminology to distinguish degrees of modularization is proposed, along with a decision-making support checklist and a diagrammatic decision-making support figure. Results indicate that the EC sub-sectors were substantially more satisfied with the application of component, structural, or traditional modularization compared with system modularization for some types of modules. Key drivers for decisions on the degree of modularization vary across module types. This paper can help the EC sector determine the most suitable degree of modularization via a decision-making support strategy.

Keywords: modularization, engineering construction, case study, decision support

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Authors: Muhammad Jahangeer Munir, Liaqat Ali Qureshi, Junaid Ahmed

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This paper presents the investigation regarding use of glass fibers in structural concrete members and determining the behavior of normal PCC, GFRC and retrofitted GFRC under different tests performed in the laboratory. Effect of retrofitting on the GFRC & PCC was investigated by using three patterns of CFRP wrapping. Properties like compressive, split tensile and flexural strength of normal GFRC and retrofitted GFRC were investigated and compared with their PCC counterparts. It was found that GFRC has more compressive strength as compared to PCC. At lower confinement pressures PCC behaves better than GFRC. Confinement efficiency was lower in GFRC as compared to PCC in terms of Split tensile strength. In case of GFRC all the patterns of wrapped CFRP strips showed more strength than their PCC counterparts.

Keywords: carbon fiber reinforced polymers, confinement, glass fibers, retrofitting

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Authors: Paulo Mendonca, Nzar Faiq Naqeshbandi

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The objective of this study is to propose an interactive design environment that outlines the underlying computational framework to reach self-supporting overhangs. The research demonstrates the digital printability of overhangs taking into consideration factors related to the geometry design, the material used, the applied support, and the printing set-up of slicing and the extruder inclination. Parametric design tools can contribute to the design phase, form-finding, and stability optimization of self-supporting structures while printing in order to hold the components in place until they are sufficiently advanced to support themselves. The challenge is to ensure the stability of the printed parts in the critical inclinations during the whole fabrication process. Facilitating the identification of parameterization will allow to predict and optimize the process. Later, in the light of the previous findings, some guidelines of simulations and physical tests are given to be conducted for estimating the structural and functional performance.

Keywords: additive manufacturing, overhangs, self-support overhangs, printability, parametric tools

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Authors: Agustin Maciel-Padilla

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This paper explores the most significant change to Japan’s security strategy since the end of World War II, in particular Prime Minister Fumio Kishida’s government publication, in late 2022, of 3 policy documents (the National Security Strategy [NSS], the National Defense Strategy and the Defense Buildup Program) that basically propose to expand the country’s military capabilities and to increase military spending over a 5-year period. These policies represent a remarkable transformation of Japan’s defense-oriented policy followed since 1946. These proposals have been under analysis and debate since they were announced, as it was also Japan’s historic ambition to strengthening its deterrence capabilities in the context of a more complex regional security environment. Even though this new defense posture has attracted significant international attention, it is far from representing a done deal because of the fact that there is still a long way to go to implement this vision because of a wide variety of political and economic issues. Japan is currently experiencing the most dangerous security environment since the end of World War II, and this situation led Japan to intensify its dialogue with the United States to reflect a re-evaluation of deterrence in the face of a rapidly worsening security environment, a changing balance of power in East Asia, and the arrival of a new era of “great power competition”. Japan’s new documents, for instance, identify China and North Korea’s as posing, respectively, a strategic challenge and an imminent threat. Japan has also noted that Russia’s invasion of Ukraine has contributed to erode the foundation of the international order. It is considered that Russia’s aggression was possible because Ukraine’s defense capability was not enough for effective deterrence. Moreover, Japan’s call for “counterstrike capabilities” results from a recognition that China and North Korea’s ballistic and cruise missiles could overwhelm Japan’s air and missile defense systems, and therefore there is an urgent need to strengthen deterrence and resilience. In this context, this paper will focus on the impact of these changes on the US-Japan alliance. Adapting this alliance to Tokyo’s new ambitions and capabilities could be critical in terms of updating their traditional protection/access to bases arrangement, interoperability and joint command and control issues, as well as regarding the security–economy nexus. While China is Japan’s largest trading partner, and trade between the two has been growing, US-Japan economic relationship has been slower, notwithstanding the fact that US-Japan security cooperation has strengthened significantly in recent years.

Keywords: us-japan alliance, japan security, great power competition, interoperability

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Authors: Wei-Ju Huang, Hung-Pin Hsu

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[Background] In congestive heart failure (CHF), it has always been the principle of clinical treatment to control the water retention mechanism in the body to prevent excessive fluid retention. Early control of sympathetic nerves, Renin-Angiotensin-Aldosterone system (RAA system, RAAS), or strengthening of Atrial Natriuretic Peptide (ANP) was the point. In RAA system, related hormones, such as angiotensin, or enzymes in the pathway, such as ACE-I, can be used with corresponding inhibitors to reduce water content.[Aim] In recent years, clinical studies have pointed out that if different mechanisms are combined, the control effect seems to be better. For example, recent studies showed that ENTRESTO, a combination of Sacubitril and Valsartan, is a good new drug for CHF. Sacubitril is a prodrug. After activation, it can inhibit neprilysin and act as a neprilysin inhibitor (ARNI) to reduce the breakdown of natriuretic peptides(ANP). Valsartan is a kind of angiotensin receptor blocker (ARB), both of which are used to treat heart failure at the same time, have excellent curative effects.[Materials and Methods] Considering the side effects of this drug, coughing and a few cases of diarrhea were observed. However, the effect of this drug on the patient's intestinal tract has not been confirmed. On the other hand, studies have pointed out that ANP supplement can improve the CHF and increase the inhibitory effect on cancer cells. Therefore, the purpose of this study is to use a special microbial detection method to prove that whether oral drugs have an effect on microorganisms.The experimental method uses Nissui Compact Dry to observe the situation in different types of microorganisms. After the drug is dissolved in water, it is implanted in a petri dish, and the presence of different microorganisms is detected through different antibody reactions to confirm whether the drug has some toxicology in the gut.[Results and Discussion]From the above experimental results, it can be known that among the effects of Sacubitril and Valsartan on the basic microbial flora of the human body, low doses had no significant effect on Escherichia coli or intestinal bacteria. If Sacubitril or Valsartan with a high concentration of 3mg/ml is used alone or under the stimulation of a high concentration of the two drugs, it has a significant inhibitory effect on Escherichia coli. However, in terms of the effect on intestinal bacteria, high concentration of Sacubitril has a more significant inhibitory effect on intestinal bacteria, while high concentration of Valsartan has a less significant inhibitory effect on intestinal bacteria. The inhibitory effect of the combination of the two drugs on intestinal bacteria is also less significant.[Conclusion]The results of this study can be used as a further reference for the possible side effects of the clinical use of Sacubitril and Valsartan on the intestinal tract of patients,

Keywords: sacubitril, valsartan, entresto, congestive heart failure (CHF)

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Authors: Andre Sanches Siqueira Campos

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Central banks can play a significant role in promoting regional economic and monetary integration by strengthening the payment and settlement systems. However, close coordination and cooperation require facilitating the implementation of reforms at domestic and cross-border levels in order to benchmark with international standards and commitments to the liberal order. This situation reflects the normative power of the regulatory globalization dimension of strong states, which may drive or constrain regional integration. In the MERCOSUR and SAARC regions, central banks have set financial initiatives that could facilitate South America and South Asia regions to move towards convergence integration and facilitate trade and investments connectivities. This is qualitative method research based on a combination of the Process-Tracing method with Qualitative Comparative Analysis (QCA). This research approaches multiple forms of data based on central banks, regional organisations, national governments, and financial institutions supported by existing literature. The aim of this research is to analyze the decision-making process of the Central Bank of Brazil (BCB) and the Reserve Bank of India (RBI) towards regional financial cooperation by identifying connectivity instruments that foster, gridlock, or redefine cooperation. The BCB and The RBI manage the monetary policy of the largest economies of those regions, which makes regional cooperation a relevant framework to understand how they provide an effective institutional arrangement for regional organisations to achieve some of their key policies and economic objectives. The preliminary conclusion is that both BCB and RBI demonstrate a reluctance to deepen regional cooperation because of the existing economic, political, and institutional asymmetries. Deepening regional cooperation is constrained by the interests of central banks in protecting their economies from risks of instability due to different degrees of development between countries in their regions and international financial crises that have impacted the international system in the 21st century. Reluctant regional integration also provides autonomy for national development and political ground for the contestation of Global Financial Governance by Brazil and India.

Keywords: Brazil, central banks, decision-making process, global financial governance, India, MERCOSUR, connectivity, payment system, regional cooperation, SAARC

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Authors: Victor A. Okenyi, Kehinde A. Alawode

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Corrosion of reinforcement in concrete structures remains a durability issue in structural engineering with the increasing cost of repair and maintenance. The mechanism and factors influencing reinforcement corrosion in concrete with various electrochemical monitoring techniques including non-destructive, destructive techniques and the roles of sensors have been reviewed with the aim of determining the monitoring technique that proved most effective in determining corrosion parameters and more practicable for the assessment of concrete durability. Electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) techniques showed great performance in evaluating corrosion kinetics and corrosion rate, respectively, while the gravimetric weight loss (GWL) technique provided accurate measurements. However, no single monitoring technique showed to be the ultimate technique, and this calls for more research work in the development of more dynamic monitoring tools capable of considering all possible corrosion factors in the corrosion monitoring process.

Keywords: corrosion, concrete structures, durability, non-destructive technique, sensor

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Authors: Germans Natuhwera, Peter Ellis, Acuda Wilson, Anne Merriman, Martha Rabwoni

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Objective: The aim of the study was to diagnose the socio-economic burden and impact of a diagnosis of cervical cancer (CC) in rural women in the context of low-resourced country Uganda, using a phenomenological enquiry. Methods: This was a multi-site phenomenological inquiry, conducted at three hospice settings; Mobile Hospice Mbarara in southwestern, Little Hospice Hoima in Western, and Hospice Africa Uganda Kampala in central Uganda. A purposive sample of women with a histologically confirmed diagnosis of CC was recruited. Data was collected using open-ended audio-recorded interviews conducted in the native languages of participants. Interviews were transcribed verbatim in English, and Braun and Clarke’s (2019) framework of thematic analysis was used. Results: 13 women with a mean age of 49.2 and age range 29-71 participated in the study. All participants were of low socioeconomic status. The majority (84.6%) had advanced disease at diagnosis. A fuller reading of transcripts produced four major themes clustered under; (1) socioeconomic characteristics of women, (2) impact of CC on women’s relationships, (3) disrupted and impaired activities of daily living (ADLs), and (4) economic disruptions. Conclusions: A diagnosis of CC introduces significant socio-economic disruptions in a woman’s and her family’s life. CC causes disability, impairs the woman and her family’s productivity hence exacerbating levels of poverty in the home. High and expensive out-of-pocket expenditure on treatment, investigations, and transport costs further compound the socio-economic burden. Decentralizing cancer care services to regional centers, scaling up screening services, subsidizing costs of cancer care services, or making cervical cancer care treatment free of charge, strengthening monitoring mechanisms in public facilities to curb the vice of healthcare workers soliciting bribes from patients, increased mass awareness campaigns about cancer, training more healthcare professionals in cancer investigation and management, and palliative care, and introducing an introductory course on gynecologic cancers into all health training institutions are recommended.

Keywords: activities of daily living, cervical cancer, out-of-pocket, expenditure, phenomenology, socioeconomic

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Authors: M. Naimur Rahman, Mohammad Tariqul Islam, Mandeep Singh Jit Singh, Norbahiah Misran

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This paper presents the architecture and exploration of a compact, circulated double Psi-shaped microstrip patch antenna for Ku-band satellite applications. The antenna is composed of the double Psi-shaped patch in opposite focus which is circulated with a ring. The antenna size is 24 mm × 18 mm and the prototype is imprinted on Rogers RT/duroid 5880 materials with the depth of 1.57 mm. The substrate has a relative permittivity of 2.2 and the dielectric constant of 0.0009. The excitation is supplied through a 50Ω microstrip line. The performance of the presented antenna has been simulated and verified with the High-Frequency Structural Simulator (HFSS). The results depict that the antenna covers the frequency spectrum 14.6 - 17.4 GHz (Ku-band) with 10 dB return loss. The antenna has a 4.40 dBi maximum gain with stable radiation patterns throughout the operating band which makes the proposed antenna compatible for the satellite application in Ku-band.

Keywords: Ku-band antenna, microstrip antenna, psi-shaped antenna, satellite applications

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Authors: Eman M. Elmazek

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Green roofs and walls are a rising technology in the global sustainable architectural industry. The idea takes great steps towards the future of sustainable design due to its many benefits. However, there are many barriers and constraints. Economical, structural, and knowledge barriers prevent the spread of the usage of green roofs and living walls. Understanding the benefits and expanding them will spread the idea. Benefits provided by these green spots interrupt and maintain the current urban cover. Food production is one of the benefits of green roofs. It can save money and energy spent in food transportation. The goal of this paper is to put a better understanding of implementing green systems. The paper aims to identify gains versus challenges facing the technology. It surveys with case studies buildings with green roofs and walls used for food production.

Keywords: green roof, green walls, urban farming, roof herb garden

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Authors: Amirhossein Dodankeh, Hadi Dabiryan, Saeed Hamze

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Using fabrics to reinforce composites considerably leads to improved mechanical properties, including resistance to the impact load and the energy absorption of composites. Warp-knitted spacer fabrics (WKSF) are fabrics consisting of two layers of warp-knitted fabric connected by pile yarns. These connections create a space between the layers filled by pile yarns and give the fabric a three-dimensional shape. Today because of the unique properties of spacer fabrics, they are widely used in the transportation, construction, and sports industries. Polyurethane (PU) foams are commonly used as energy absorbers, but WKSF has much better properties in moisture transfer, compressive properties, and lower heat resistance than PU foam. It seems that the use of warp-knitted spacer fabric reinforced PU foam (WKSFRF) can lead to the production and use of composite, which has better properties in terms of energy absorption from the foam, its mold formation is enhanced, and its mechanical properties have been improved. In this paper, the energy absorption efficiency (EAE) of WKSFRF under low-velocity impact is investigated experimentally. The contribution of the effect of each of the structural parameters of the WKSF on the absorption of impact energy has also been investigated. For this purpose, WKSF with different structures such as two different thicknesses, small and large mesh sizes, and position of the meshes facing each other and not facing each other were produced. Then 6 types of composite samples with different structural parameters were fabricated. The physical properties of samples like weight per unit area and fiber volume fraction of composite were measured for 3 samples of any type of composites. Low-velocity impact with an initial energy of 5 J was carried out on 3 samples of any type of composite. The output of the low-velocity impact test is acceleration-time (A-T) graph with a lot deviation point, in order to achieve the appropriate results, these points were removed using the FILTFILT function of MATLAB R2018a. Using Newtonian laws of physics force-displacement (F-D) graph was drawn from an A-T graph. We know that the amount of energy absorbed is equal to the area under the F-D curve. Determination shows the maximum energy absorption is 2.858 J which is related to the samples reinforced with fabric with large mesh, high thickness, and not facing of the meshes relative to each other. An index called energy absorption efficiency was defined, which means absorption energy of any kind of our composite divided by its fiber volume fraction. With using this index, the best EAE between the samples is 21.6 that occurs in the sample with large mesh, high thickness, and meshes facing each other. Also, the EAE of this sample is 15.6% better than the average EAE of other composite samples. Generally, the energy absorption on average has been increased 21.2% by increasing the thickness, 9.5% by increasing the size of the meshes from small to big, and 47.3% by changing the position of the meshes from facing to non-facing.

Keywords: composites, energy absorption efficiency, foam, geometrical parameters, low-velocity impact, warp-knitted spacer fabric

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Authors: Atasi Dan, Kamanio Chattopadhyay, Bikramjit Basu

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A cost-effective titanium diboride (TiB2) paint coating has been developed on stainless steel substrate using commercially available polyvinylpyrrolidone as a binder by convenient dip-coating technique. The emittance of the coating has been explored by tailoring various process parameters to obtain highest thermal radiation. The optimized coating has achieved a high thermal emittance of 0.85. In addition, the coating exhibited an excellent thermal stability while heat-treated at 500 °C in air. Along with the emittance, the structural and physical properties of the As-deposited and heat-treated coatings have been investigated systematically. The high temperature annealing has not affected the emittance, chemical composition and morphology of the coating significantly. Hence, the fabricated paint coating is expected to open up new possibilities for using it as a low-cost, thermally stable emitter in high temperature applications.

Keywords: titanium diboride, emittance, paint coating, thermal stability

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Authors: Sukhleen Bindra Narang, Dalveer Kaur, Kunal Pubby

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Dielectric ceramic samples in the BaO-Re2O3-TiO2 ternary system were synthesized with structural formula Ba2-xRe4+2x/3Ti8O24 where Re= rare earth metal and Re= Sm and La where x varies from 0.0 to 0.6 with step size 0.1. Polycrystalline samples were prepared by the conventional solid state reaction technique. The dielectric, electrical and impedance analysis of all the samples in the frequency range 1KHz- 1MHz at room temperature (25°C) have been done to get the understanding of electrical conduction and dielectric relaxation and their correlation. Dielectric response of the samples at lower frequencies shows dielectric dispersion while at higher frequencies it shows dielectric relaxation. The ac conductivity is well fitted by the Jonscher law (σac = σdc+Aωn). The spectroscopic data in the impedance plane confirms the existence of grain contribution to the relaxation. All the properties are found out to be function of frequency as well as the amount of substitution.

Keywords: dielectric ceramics, dielectric constant, loss tangent, AC conductivity, impedance spectroscopy

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Authors: Feng Fu, Ahmad Bazgir

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This study aimed to investigate and examine the structural behaviour of steel fibre reinforced concrete slabs when subjected to impact loading using drop weight method. A number of compressive tests, tensile splitting tests, as well as impact tests were conducted. The experimental work consists of testing both conventional reinforced slabs and SFRC slabs. Parameters to be considered for carrying out the test will consist of the volume fraction of steel fibre, type of steel fibres, drop weight height and number of blows. Energy absorption of slabs under impact loading and failure modes were examined in-depth and compared with conventional reinforced concrete slab are investigated.

Keywords: steel fibre reinforce concrete, compressive test, tensile splitting test, impact test

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Authors: Jatinderkumar R. Saini

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E-mail has become a key mechanism of electronic communication. This is truer for professional organizations that like to communicate with their subjects online and are slowly shifting to paper-less office. The current paper focuses specifically on academic institutions offering Engineering course in Gujarat state and attempts for textual analysis of the usernames of the institutional e-mail addresses. We found that the institutions tend to design the username segment of their e-mail addresses by choosing words or combination of words from specific categories. The paper also highlights the use of special characters, digits and random words in designing the usernames. On the sidelines, the paper lists the style of employing department names and designations for the design process. To the best of our knowledge, this is the first formal attempt to analyze the selection of words employed for designing username segment of e-mail addresses of Engineering institutions.

Keywords: e-mail address, institute, engineering, username

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Authors: H. Heydari, B. Konuklugil, P. Proksch

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Marine-derived fungi can produce interesting bioactive secondary metabolites that can be considered the potential for drug development. Turkey is a country of a peninsula surrounded by the Black Sea at the north, the Aegean Sea at the west, and the Mediterranean Sea at the south. Despite the approximately 8400 km of coastline, studies on marine secondary metabolites and their biological activity are limited. In our ongoing search for new natural products with different bioactivities produced by the marine-derived fungi, we have investigated secondary metabolites of Turkish collection of the marine sea slug (Peltodoris atromaculata) associated fungi Hypocrea nigricans collected from Seferihisar in the Egean sea. According to the author’s best knowledge, no study was found on this fungal species in terms of secondary metabolites. Isolated from ethyl acetate extract of the culture of Hypocrea nigricans were (isodihydroauroglaucin,tetrahydroauroglaucin and dihydroauroglaucin. The structures of the compounds were established based on an NMR and MS analysis. Structural elucidation of another isolated secondary metabolite/s continues.

Keywords: Hypocrea nigricans, isolation, marine fungi, secondary metabolites

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Authors: Khoa Tan Nguyen, Tuan Anh Le, Kihak Lee

Abstract:

This paper presents the flexural response of Reinforced Geopolymer Concrete (RGPC) beams. A commercial finite element (FE) software ABAQUS has been used to perform a structural behavior of RGPC beams. Using parameters such: stress, strain, Young’s modulus, and Poisson’s ratio obtained from experimental results, a beam model has been simulated in ABAQUS. The results from experimental tests and ABAQUS simulation were compared. Due to friction forces at the supports and loading rollers; slip occurring, the actual deflection of RGPC beam from experimental test results were slightly different from the results of ABAQUS. And there is good agreement between the crack patterns of fly ash-based geopolymer concrete generated by FE analysis using ABAQUS, and those in experimental data.

Keywords: geopolymer concrete beam, finite element mehod, stress strain relation, modulus elasticity

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Authors: Victor Pena Ribeiro, Caroline Arruda, Jennyfer Andrea Aldana Mejia, Jairo Kenupp Bastos

Abstract:

Leishmaniasis is a serious health problem around the world. The treatment of infected individuals with pentavalent antimonial drugs is the main therapeutic strategy. However, they present high toxicity and persistence side effects. Therefore, the discovery of new and safe natural-derived therapeutic agents against leishmaniasis is important. Propolis is a resin of viscous consistency produced by Apis mellifera bees from parts of plants. The main types of Brazilian propolis are green, red, yellow and brown. Thus, the aim of this work was to investigate the chemical composition and leishmanicidal properties of a brown propolis (BP). For this purpose, the hydroalcoholic crude extract of BP was obtained and was fractionated by liquid-liquid chromatography. The chemical profile of the extract and its fractions were obtained by HPLC-UV-DAD. The fractions were submitted to preparative HPLC chromatography for isolation of the major compounds of each fraction. They were analyzed by NMR for structural determination. The volatile compounds were obtained by hydrodistillation and identified by GC/MS. Promastigote forms of Leishmania amazonensis were cultivated in M199 medium and then 2×106 parasites.mL-1 were incubated in 96-well microtiter plates with the samples. The BP was dissolved in dimethyl sulfoxide (DMSO) and diluted into the medium, to give final concentrations of 1.56, 3.12, 6.25, 12.5, 25 and 50 µg.mL⁻¹. The plates were incubated at 25ºC for 24 h, and the lysis percentage was determined by using a Neubauer chamber. The bioassays were performed in triplicate, using a medium with 0.5% DMSO as a negative control and amphotericin B as a positive control. The leishimnicidal effect against promastigote forms was also evaluated at the same concentrations. Cytotoxicity experiments also were performed in 96-well plates against normal (CHO-k1) and tumor cell lines (AGP01 and HeLa) using XTT colorimetric method. Phenolic compounds, flavonoids, and terpenoids were identified in brown propolis. The major compounds were identified as follows: p-coumaric acid (24.6%) for a methanolic fraction, Artepelin-C (29.2%) for ethyl acetate fraction and the compounds of hexane fraction are in the process of structural elucidation. The major volatile compounds identified were β-caryophyllene (10.9%), germacrene D (9.7%), nerolidol (10.8%) and spathulenol (8.5%). The propolis did not show cytotoxicity against normal cell lines (CHO) with IC₅₀ > 100 μg.mL⁻¹, whereas the IC₅₀ < 10 μg.mL⁻¹ showed a potential against the AGP01 cell line, propolis did not demonstrate cytotoxicity against HeLa cell lines IC₅₀ > 100 μg.mL⁻¹. In the determination of the leishmanicidal activity, the highest (50 μg.mL⁻¹) and lowest (1.56 μg.mL⁻¹) concentrations of the crude extract caused the lysis of 76% and 45% of promastigote forms of L. amazonensis, respectively. To the amastigote form, the highest (50 μg.mL⁻¹) and lowest (1.56 μg.mL⁻¹) concentrations caused the mortality of 89% and 75% of L. amazonensis, respectively. The IC₅₀ was 2.8 μg.mL⁻¹ to amastigote form and 3.9 μg.mL⁻¹ to promastigote form, showing a promising activity against Leishmania amazonensis.

Keywords: amastigote, brown propolis, cytotoxicity, promastigote

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Authors: Malizgani Paul Chavula

Abstract:

Background: Comprehensive sexuality education (CSE) plays a critical role in promoting youth and adolescents’ sexual and reproductive health and well-being. However, little is known about the enablers and barriers affecting the integration of CSE into educational programmes. The aim of this review is to explore positive and negative factors influencing the integration of CSE into national curricula and educational systems in low- and middle-income countries. Methods: We conducted a systematic literature review (January 2010 to August 2022). The results accord with the Preferred Reporting Items for Systematic Reviews and Meta-analysis standards for systematic reviews. Data were retrieved from the PubMed, Cochrane, Google Scholar, and Web of Hinari databases. The search yielded 431 publications, of which 23 met the inclusion criteria for full-text screening. The review is guided by an established conceptual framework that incorporates the integration of health innovations into health systems. Data were analyzed using a thematic synthesis approach. Results: The magnitude of the problem is evidenced by sexual and reproductive health challenges such as high teenage pregnancies, early marriages, and sexually transmitted infections. Awareness of these challenges can facilitate the development of interventions and the implementation and integration of CSE. Reported aspects of the interventions include core CSE content, delivery methods, training materials and resources, and various teacher-training factors. Reasons for adoption include perceived benefits of CSE, experiences and characteristics of both teachers and learners, and religious, social, and cultural factors. Broad system characteristics include strengthening links between schools and health facilities, school and community-based collaboration, coordination of CSE implementation, and the monitoring and evaluation of CSE. Ultimately, the availability of resources, national policies and laws, international agendas, and political commitment will impact upon the extent and level of integration. Conclusion: Social, economic, cultural, political, legal, and financial contextual factors influence the implementation and integration of CSE into national curricula and educational systems. Stakeholder collaboration and involvement in the design and appropriateness of interventions is critical.

Keywords: comprehensive sexuality education, factors, integration, sexual reproductive health rights

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Authors: Lotfi Hedi Khezami, Mohamed Ben Rabha, N. Sboui, Mounir Gaidi, B. Bessais

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Metal-nano particle-assisted Chemical Etching is an extraordinary developed wet etching method of producing uniform semiconductor nano structure (nano wires) from patterned metallic film on crystalline silicon surface. The metal films facilitate the etching in HF and H2O2 solution and produce silicon nanowires (SiNWs). Creation of different SiNWs morphologies by changing the etching time and its effects on optical and opto electronic properties was investigated. Combination effect of formed SiNWs and stain etching treatment in acid (HF/HNO3/H2O) solution on the surface morphology of Si wafers as well as on the optical and opto electronic properties are presented in this paper.

Keywords: stain etching, porous silicon, silicon nanowires, reflectivity, lifetime, solar cells

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Authors: Tosin Osasona

Abstract:

The Nigeria Police Force bears the constitutional mandate as the primary policing agency for the protection of life and property within Nigeria; however, the police have an historical ill-reputation for corruption, ineptitude and impunity. Using the institutional theory of police as the framework of analysis, the paper argues that the performance of the police in Nigeria mirrors the dominant political, social and economic institutions and the structural environment of the Nigerian state. The article puts in perspective the deliberate political decision to underfund the police, leaving officers of the force the extra task of foraging for funds to undertake the duty that the Nigeria state primarily exists for; the article further explores the nexus between corruption in the police in Nigeria and the issue of funding. The article finds that the Nigerian state, by deliberately under-funding the police, while expecting the agency to perform its duties, has indirectly sanctioned the corruption of the force and approved the cooption of the institution of police and policing for private use in Nigeria.

Keywords: Police Corruption, Funding , Informal Taxation, POlice Checkpoint

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