Search results for: mechanical behavior of bone

Authors: L. Sánchez-Abella, I. Loinaz, H-J. Grande, D. Dupin

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Aseptic loosening remains as the principal cause of revision in total hip arthroplasty (THA). For long-term implantations, submicron particles are generated in vivo due to the inherent wear of the prosthesis. When this occurs, macrophages undergo phagocytosis and secretion of bone resorptive cytokines inducing osteolysis, hence loosening of the implanted prosthesis. Therefore, new technologies are required to reduce the wear of the bearing materials and hence increase the life-span of the prosthesis. Our strategy focuses on surface modification of the bearing materials with a hydrophilic coating based on cross-linked water-soluble (meth)acrylic monomers to improve their tribological behavior. These coatings are biocompatible, with high swelling capacity and antifouling properties, mimicking the properties of natural cartilage, i.e. wear resistance with a permanent hydrated layer that prevents prosthesis damage. Cartilage mimicking based coatings may be also used to protect medical device surfaces from damage and scratches that will compromise their integrity and hence their safety. However, there are only a few reports on the mechanical and tribological characteristics of this type of coatings. Clear beneficial advantages of this coating have been demonstrated in different conditions and different materials, such as Ultra-high molecular weight polyethylene (UHMWPE), Polyethylene (XLPE), Carbon-fiber-reinforced polyetheretherketone (CFR-PEEK), cobalt-chromium (CoCr), Stainless steel, Zirconia Toughened Alumina (ZTA) and Alumina. Using routine tribological experiments, the wear for UHMWPE substrate was decreased by 75% against alumina, ZTA and stainless steel. For PEEK-CFR substrate coated, the amount of material lost against ZTA and CrCo was at least 40% lower. Experiments on hip simulator allowed coated ZTA femoral heads and coated UHMWPE cups to be validated with a decrease of 80% of loss material. Further experiments on hip simulator adding abrasive particles (1 micron sized alumina particles) during 3 million cycles, on a total of 6 million, demonstrated a decreased of around 55% of wear compared to uncoated UHMWPE and uncoated XLPE. In conclusion, CIDETEC‘s hydrogel coating technology is versatile and can be adapted to protect a large range of surfaces, even in abrasive conditions.

Keywords: cartilage, hydrogel, hydrophilic coating, joint

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Authors: Felix Jr. Garde, Eric Augustus Tingatinga

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Most analysis procedures of reinforced concrete (RC) slabs are based on elastic theory. When subjected to large forces, however, slabs deform beyond elastic range and the study of their behavior and performance require nonlinear analysis. This paper presents a numerical model to simulate nonlinear behavior of RC slabs using rigid body-spring discrete element method. The proposed slab model composed of rigid plate elements and nonlinear springs is based on the yield line theory which assumes that the nonlinear behavior of the RC slab subjected to transverse loads is contained in plastic or yield-lines. In this model, the displacement of the slab is completely described by the rigid elements and the deformation energy is concentrated in the flexural springs uniformly distributed at the potential yield lines. The spring parameters are determined from comparison of transverse displacements and stresses developed in the slab obtained using FEM and the proposed model with assumed homogeneous material. Numerical models of typical RC slabs with varying geometry, reinforcement, support conditions, and loading conditions, show reasonable agreement with available experimental data. The model was also shown to be useful in investigating dynamic behavior of slabs.

Keywords: RC slab, nonlinear behavior, yield line theory, rigid body-spring discrete element method

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Authors: Asmaa M. Marzouk, Abdallah M. Elshaer

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Despite the well-recognized value of shopping as a revenue-generating resource, little effort was made to investigate what is the structure of tourists’ shopping behavior, which in turn, affect their travel experience. The purpose of this paper is to study the structure of tourists’ shopping process to better understand their shopping behavior by investigating factors that influence this activity other than hotels tyranny. This study specifically aims to propose a model incorporating those all variables. This empirical study investigates the shopping experience of international tourists using a questionnaire aimed to examine multinational samples selected from the tourist population visiting a specific destination in Egypt. This study highlights the various stakeholders that make tourists do shop independent of hotels. The results, therefore, demonstrate the relationship between the shopping process entities involved and configure the variables within the model in a way that provides a viable solution for visitors to avoid the tyranny of hotel facilities and amenities on the public markets.

Keywords: hotels’ amenities, shopping process, tourist behavior, tourist satisfaction

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Authors: Loredana Elena Nita, Maria Bercea, Aurica P. Chiriac, Iordana Neamtu

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The paper is devoted to the behavior of gels based on poly(itaconic anhydride-co-3, 9-divinyl-2, 4, 8, 10-tetraoxaspiro (5.5) undecane) copolymers, with different ratio between the comonomers, and hyaluronic acid (HA). The gel formation was investigated by small-amplitude oscillatory shear measurements following the viscoelastic behavior as a function of gel composition, temperature and shear conditions. Hyaluronic acid was investigated in the same conditions and its rheological behavior is typical to viscous fluids. In the case of the copolymers, the ratio between the two comonomers influences the viscoelastic behavior, a higher content of itaconic anhydride favoring the gel formation. Also, the sol-gel transition was evaluated according to Winter-Chambon criterion that identifies the gelation point when the viscoelastic moduli (G’ and G”) behave similarly as a function of oscillation frequency. From rheological measurements, an optimum composition was evidenced for which the system presents a typical gel-like behavior at 37 °C: the elastic modulus is higher than the viscous modulus and they are not dependent on the oscillation frequency. The formation of the 3D macroporous network was also evidenced by FTIR spectra, SEM microscopy and chemical imaging. These hydrogels present a high potential as drug delivery systems.

Keywords: copolymer, viscoelasticity, gelation, 3D network

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Authors: Netta Horesh Reinman

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The inability to communicate feelings and thoughts to people close to oneself may be an important risk factor for suicidal behavior. This inability has been operationalized in the concept of “self-disclosure.” The purpose of this paper was to evaluate the correlation of self-disclosure with suicidal behavior in adolescents. Eighty consecutive admissions to an adolescent psychiatric inpatient unit were evaluated. Thirty-four were suicide attempters, 18 were suicidal ideators, and 18 were non-suicidal. Assessment measures included the Child Suicide Potential Scale, the Suicide Intent Scale, the Suicide Ideation Scale, and the Self-Disclosure Scale. The results show that low self-disclosure levels are associated with suicidal thinking, suicide attempts and suicidal attitudes. Thus, low self-disclosure may well be a risk factor worthy of further evaluation in the attempt to understand adolescent suicidal behavior.

Keywords: self disclosure, suicide, adolescents, treatment

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Authors: Ehsan Kadkhodaie, Shahin Parvar, Soroush Senemar, Mostafa Shriat, Abdolrasoul Malekpour

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The role of oil in supra distribution transformers is so critical and, several standards in determining the quality of oil have been offered. So far, moisture, viscosity and insulation protection of the oil have been measured based on mechanical and chemical methods and systems such as kart fisher, falling ball and TDM 4000 that most of these techniques are destructive and have many problems such as pollution. In this study, due to the properties of oil and also physical behavior of ultrasound wave new method was designed to in the determination of oil indicators including viscosity and moisture. The results show the oil viscosity can be found from the relationship μ = 42.086/√EE and moisture from (PLUS+) = −15.65 (PPM) + 26040 relationship.

Keywords: oil, viscosity, moisture, ultrasonic waves

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Authors: Narumon Piaseu

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This survey research was aimed to describe and compare consumption behavior of health risk food among students in Suan Sunandha Rajabhat University. Sample included 400 undergraduate students enrolled in the first semester of 2008 academic year. Data were collected by using self reported questionnaire developed by the researcher. Data were then analyzed by descriptive statistics including frequency, percentage, mean, standard deviation, and inferential statistics including independent t-test, and Oneway ANOVA. Results revealed that most of the sample were women (67%), enrolled in social related programs (74%). Approximately half of them (45.5%) stayed in dormitory. The mean of monthly income was 5,164 Baht and daily food expenditure was 114.55 Baht. Majority of them (83%) had ready-to-eat food. A major factor influencing their food selection was their parents (61%). A main reason for their food selection was food that looks good (70.75%). Almost half of them (46.25%) had heavy exercise less than 3 times per week. Regarding knowledge on health risk food, 43.5% of the sample had good knowledge. The followings were moderate (41%) and poor (41%). Most of the sample (60.75%) had consumption behavior at low risk. The following was at moderate risk (37.25%). Only 2% were at high risk. Among the sample, consumption behavior of health risk food were significantly different in years of study (F = 3.168, p = .024), daily food expenditure (F = 8.950, p <.001), and knowledge on health risk food (F = 37.856, p <.001), while no significant difference in consumption behavior of health risk food was found in those with a difference in gender, program of study, living place, and monthly income. Results indicate the importance of providing knowledge regarding health risk food for students and their parents in order to promote appropriate food consumption behavior among the students.

Keywords: food consumption, risky behavior, Suan Sunandha Rajabhat University, health risk

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Authors: Talebi Aliasghar, Ebrahimpour Komeleh Hooman, Maghsoudi Ali Akbar

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In reinforced concrete (RC) structures, beam-column connection region has a considerable effect on the behavior of structures. Using fiber reinforcement polymer (FRP) for the strengthening of connections in RC structures can be one of the solutions to retrofitting this zone which result in the enhanced behavior of structure. In this paper, these changes in behavior by using FRP for high strength concrete beam-column connection have been studied by finite element modeling. The concrete damage plasticity (CDP) model has been used to analyze the RC. The results illustrated a considerable development in load-bearing capacity but also a noticeable reduction in ductility. The study also assesses these qualities for several modes of strengthening and suggests the most effective mode of strengthening. Using FRP in flexural zone and FRP with 45-degree oriented fibers in shear zone of joint showed the most significant change in behavior.

Keywords: HSC, beam-column connection, Fiber Reinforcement Polymer, FRP, Finite Element Modeling, FEM

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Authors: Charita Jashi

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The aim of the paper is to explore the role of social marketing in changing the behavior of consumers on road safety, identify critical aspects and priority needs which impede the implementation of road safety program in Georgia. Given the goals of the study, a quantitative method was used to carry out interviews for primary data collection. This research identified the awareness level of road safety, legislation base, and marketing interventions to change behavior of drivers and pedestrians. During several years the non-governmental sector together with the local authorities and media have been very intensively working on the road safety issue in Georgia, but only seat-belts campaign should be considered rather successful. Despite achievements in this field, efficiency of road safety programs far from fulfillment and needs strong empowering.

Keywords: road safety, social marketing interventions, behavior change, well-being

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Authors: Ela Ari, Aysi̇ma Findikoglu

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Consumers’ switching GSM operators’ has been an important research issue since the rise of their competitive offers. Recent research has looked at consumer switching behavior through the theory of planned behavior, but not yet extended the theory with identity, psycho-social and cultural influences within the service context. This research explores an extended version of the theory of planned behavior including social and financial risks and brand loyalty. Moreover, the role of individualism and collectivism at the individual level is investigated in a collectivistic culture that moves toward to individualism due to changing family relationships, use of technology and education. Our preliminary analysis showed that financial risk and vertical individualism prove to be a significant determinant of intention to switch. The study also investigates social risk and intention, subjective norm, perceived behavioral control relationship. The effect of individualism and collectivism and attitudes relationship has been also examined within a service industry. Implications for marketing managers and scholars are also discussed.

Keywords: attitude, individualism, intention, subjective norm

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Authors: F. Saadi, M. Fatahi, M. Heidari

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Aim of this work was to determine the approximate glass forming composition range of Ni-Sn system for the alloys produced by mechanical alloying. It was predicted by Miedema semi-empirical model that the composition had to be in the range of 30-60 wt. % tin, while Ni-40Sn had the most susceptibility to produce amorphous alloy. In the next stage, some different compositions of Ni-Sn were mechanically alloyed, where one of them had the proper predicted composition. Products were characterized by XRD analysis. There was a good agreement between calculation and experiments, in which Ni-40Sn alloy had the most amorphization degree.

Keywords: Ni-Sn system, mechanical alloying, Amorphous alloy, Miedema model

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Authors: Gargi S. Kumar, Mrinmoyi Kulkarni

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Food choice behavior is complex and determined by biological, psychological, socio-cultural, and economic factors. The past two decades, have seen dramatic changes in food consumption patterns among urban Indian consumers. The objective of the current study was to evaluate perceptions about changes with respect to food choice behavior. Ten participants [urban men and women] ranging in age from 40 to 65 were selected and in-depth interviews were conducted with a set of open ended questions. The recorded interviews were transcribed and thematically analyzed using inductive, open and axial coding. The results identified themes that act as drivers and consequences of change in food choice behavior. Drivers such as globalization [sub themes of urbanization, education, income, and work environment], media and advertising, changing gender roles, women in the workforce, and change in family structure have influenced food choice, both at an individual and national level. The consequences of changes in food choice were health implications, processed food consumption, food decisions driven by children and eating out among others. The study reveals that, over time, food choices change and evolve. However it is interesting to note how market forces and culture interact to influence individual behavior and the overall food environment which subsequently affects food choice and the health of the people.

Keywords: change, consequences, drivers, food choice, globalization

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Authors: B. A. Mir, Asim Malik

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Bottom ash is a by-product of the combustion process of coal in furnaces in the production of electricity in thermal power plants. In India, about 75% of total power is produced by using pulverized coal. The coal of India has a high ash content which leads to the generation of a huge quantity of bottom ash per year posing the dual problem of environmental pollution and difficulty in disposal. This calls for establishing strategies to use this industry by-product effectively and efficiently. However, its large-scale utilization is possible only in geotechnical applications, either alone or with soil. In the present investigation, bottom ash was collected from National Capital Power Station Dadri, Uttar Pradesh, India. Test samples of bottom ash admixed with 20% clayey soil were prepared and treated with different cement content by weight and subjected to various laboratory tests for assessing its suitability as an engineered construction material. This study has shown that use of 10% cement content is a viable chemical additive to enhance the mechanical properties of bottom ash, which can be used effectively as an engineered construction material in various geotechnical applications. More importantly, it offers an interesting potential for making use of an industrial waste to overcome challenges posed by bottom ash for a sustainable environment.

Keywords: bottom ash, environmental pollution, solid waste, sustainable environment, waste utilization

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Authors: Roxana Maria Angelescu, Doina Răducanu, Mariana Lucia Angelescu, Ion Cincă, Vasile Dănuţ Cojocaru, Cosmin Cotruț, Şerban Nicolae

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Titanium alloys are often used for biomedical applications as hard tissue replacements, such as: orthopedic implants, spinal fixation devices and dental implants. Their advantages are well known and demonstrated: excellent mechanical properties, biocompatibility and good corrosion resistance, but it is also known that the main disadvantage of the metallic materials is their tendency of corrosion in in-vivo environments. In 1987, titanium was found to be the only metallic biomaterial that osseointegrates. The aim of this study was to investigate the microstructure and the corrosion behavior of the Ti-20Nb-5Ta wt% alloy. In this case Nb stabilizes the β-Ti structure and Ta is a highly passivating metal. The as studied alloy was melt under argon protective atmosphere in a levitation induction melting furnace, type FIVE CELES - MP25, with a nominal power of 25 kW and a melting capacity of 30 cm3. The microstructure of the as studied alloy was analyzed by using the electronic microscope Tescan Vega II-XMU. The phase structure of the as studied alloy was determined, as well as the crystalline grain size (100-200µ). To determine the corrosion behavior of the as studied alloy, the technique used was the linear polarization, with the PARSTAT 4000 potentiostat, produced by Princeton Applied Research; potentiodynamic curves were obtained with the VeraStudio v.2.4.2 software.

Keywords: corrosion resistance, microstructure, titanium alloys

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Authors: M. Kozłowski, M. Kadela

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Foamed concrete is known for its low self-weight and excellent thermal and acoustic properties. For many years, it has been used worldwide for insulation to foundations and roof tiles, as backfill to retaining walls, sound insulation, etc. However, in the last years it has become a promising material also for structural purposes e.g. for stabilization of weak soils. Due to favorable properties of foamed concrete, many interests and studies were involved to analyze its strength, mechanical, thermal and acoustic properties. However, these studies do not cover the investigation of fracture energy which is the core factor governing the damage and fracture mechanisms. Only limited number of publications can be found in literature. The paper presents the results of experimental investigation and numerical campaign of foamed concrete based on three-point bending test of beams with initial notch. First part of the paper presents the results of a series of static loading tests performed to investigate the fracture properties of foamed concrete of varying density. Beam specimens with dimensions of 100×100×840 mm with a central notch were tested in three-point bending. Subsequently, remaining halves of the specimens with dimensions of 100×100×420 mm were tested again as un-notched beams in the same set-up with reduced distance between supports. The tests were performed in a hydraulic displacement controlled testing machine with a load capacity of 5 kN. Apart from measuring the loading and mid-span displacement, a crack mouth opening displacement (CMOD) was monitored. Based on the load – displacement curves of notched beams the values of fracture energy and tensile stress at failure were calculated. The flexural tensile strength was obtained on un-notched beams with dimensions of 100×100×420 mm. Moreover, cube specimens 150×150×150 mm were tested in compression to determine the compressive strength. Second part of the paper deals with numerical investigation of the fracture behavior of beams with initial notch presented in the first part of the paper. Extended Finite Element Method (XFEM) was used to simulate and analyze the damage and fracture process. The influence of meshing and variation of mechanical properties on results was investigated. Numerical models simulate correctly the behavior of beams observed during three-point bending. The numerical results show that XFEM can be used to simulate different fracture toughness of foamed concrete and fracture types. Using the XFEM and computer simulation technology allow for reliable approximation of load–bearing capacity and damage mechanisms of beams made of foamed concrete, which provides some foundations for realistic structural applications.

Keywords: foamed concrete, fracture energy, three-point bending, XFEM

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Authors: Lilia Righi

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Recently, the fashion industry has demonstrated a keen interest in sustainability and the environment. Sustainable fashion has huge potential and appeals to environmentally conscious Generation Z shoppers. Meanwhile, Generation Z customers have attracted researchers' interest due to their overconsumption of clothing. However, most studies in this area focus on designing or producing sustainable clothing, with little exploration of consumers. To fill this gap, the present study aims to determine the important factors influencing Generation Z consumers' decisions to purchase sustainable fashion by mobilizing the theory of planned behavior (TPB). It uses deductive qualitative research based on 18 semi-structured interviews with Generation Z consumers in France. Qualitative data will be analyzed using reflective thematic analysis. On a theoretical level, this research contributes to enriching the literature by mobilizing, for the first time, the theory of planned behavior in the context of sustainable fashion. On a practical level, the results can help practitioners determine effective marketing strategies to persuade Generation Z to consume sustainable clothing.

Keywords: generation Z, qualitative methodology, sustainable fashion, theory of planned behavior (TPB).

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Authors: Chinazo Onyeka Eziuzo

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This work presents the simulation and control of the flywheel system in the rotor of a wind turbine using Simulink and OpenFAST for assessing the effect on the mechanical loads. This concept allows the flywheel system to serve two main tasks: supporting the power system and mitigating the mechanical loads in the wind turbine. These tasks are grouped into four control scenarios; scenario 1 represents steadying the power infeed in the Flywheel, scenario 2 represents steadying power with FW and grid loss, scenario 3 represents mitigating excitations from gravity, and scenario 4 represents damping in-plane blade vibrations. The s-function of the OpenFAST model was used to substitute the given 1st Eigen mode model of the WT. After that, the simulations were run for the above-listed scenarios. Additionally, the effects of the control options on the mechanical loads were assessed, and it was established that the FW system assists in steadying infeed power and mechanical load mitigation.

Keywords: simulation, control, wind turbine, OpenFAST

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Authors: N. Reppas, Y. L. Gui, B. Wetenhall, C. T. Davie, J. Ma

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A theoretical constitutive model describing the stress-strain behavior of rock subjected to different confining pressures is presented. A bounding surface plastic model with hardening effects is proposed which includes the effect of temperature drop. The bounding surface is based on a mapping rule and the temperature effect on rock is controlled by Poisson’s ratio. Validation of the results against available experimental data is also presented. The relation of deviatoric stress and axial strain is illustrated at different temperatures to analyze the effect of temperature decrease in terms of stiffness of the material.

Keywords: bounding surface, cooling of rock, plasticity model, rock deformation, elasto-plastic behavior

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Authors: Terri Cole, Fay Sweeting

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Abuse of position for sexual gain by police is defined as behavior involving individuals taking advantage of their role to pursue a sexual or improper relationship. Previous research has considered whether it involves ‘bad apples’ - individuals with poor moral ethos or ‘bad barrels’ – broader organizational flaws which may unconsciously allow, minimize, or do not effectively deal with such behavior. Low level sexual misconduct (e.g., consensual sex on duty) is more common than more serious offences (e.g., rape), yet the impact of such behavior can have severe implications not only for those involved but can also negatively undermine public confidence in the police. This ongoing, collaborative research project has identified variables from 514 historic case files from 35 UK police forces in order to identify potential risk indicators which may lead to such behavior. Quantitative analysis using logistic regression and the Cox proportion hazard model has resulted in the identification of specific risk factors of significance in prediction. Factors relating to both perpetrator background such as a history of intimate partner violence, debt, and substance misuse coupled with in work behavior such as misusing police systems increase the risk. Findings are able to provide pragmatic recommendations for those tasked with identifying potential or investigating suspected perpetrators of misconduct.

Keywords: abuse of position, forensic psychology, misconduct, sexual abuse

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Authors: Hamed Ahmadi Moghadam, Omolbanin Arasteh Khoshbin

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The possibility of using of rice husk ash (RHA) of Guilan (a province located in the north of Iran) (RHA) in concrete was studied by performing experiments. Mechanical properties and shrinkage and expansion of concrete containing different percentage of RHA and the control concrete consisting of cement type II were investigated. For studying, a number of cube and prism concrete specimens containing of 5 to 30% of RHA with constant water to binder ratio of 0.4 were casted and the compressive strength, tensile strength, shrinkage and expansion for water curing conditions up to 360 days were measured. The tests results show that the cement replacement of rice husk ash (RHA) caused both the quality and mechanical properties alterations. It is shown that the compressive strength, tensile strength increase also shrinkage and expansion of specimens were increased that should be controlled in mass concrete structures.

Keywords: rice husk ash, mechanical properties, shrinkage and expansion, Pozzolan

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Authors: Razan Salem

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This study aims to investigate the investment behavior of Arab women (in regards to their herding behavior, risk tolerance, confidence and investment literacy levels). This study aims to investigate the relationship between three demographic factors (age, income, education) and the investment behavior of Arab women. On average, women in the Arab region face several obstacles that limit them from fully participating in stocks investments. In the context, this study focuses on extending the existing literature to include Arab women individuals and their investment behaviors. To achieve the study’s objective, the researcher distributed 600 close-ended online questionnaires to a sample of Arab male and female individual investors in both Saudi Arabia and Jordan. The researcher used quantitative statistical methods (frequency distribution along with the Kruskal-Wallis H Test and the Mann-Whitney U Test) to analyze the 550 questionnaire respondents. The findings indicated that only age, educational level, and annual income level are associated with the investment behavior of Arab women, where age is only negatively associated with their financial risk tolerance levels. Additionally, income level is positively associated with Arab women‘s confidence and investment literacy levels, while educational level is only associated positively with their investment confidence levels. According to annual income, Arab women with lower incomes have lower confidence and investment literacy levels. The limited income level might prevent the sample Arab women from investing in the financial information and advisors that may help in improving their investment literacy levels. Furthermore, Arab women with lower educational levels have lower investment literacy levels and thus, this may limit their stock investments. Overall, the study contributes to the existing literature by focusing directly on examining the investment behavior of Arab women and its association with age, annual income, and education. Generally, there are scarce existing studies that investigate the association of demographic factors with the investment behavior of women only in regards to their herding behavior, risk tolerance, investment confidence, and investment literacy levels (combined), especially Arab women investors.

Keywords: Arab region, demographic factors, investment behavior, women investors

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Authors: Belal Almassri, Amjad Kreit, Firas Al Mahmoud, Raoul François

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Corrosion of steel in reinforced concrete leads to several major defects. Firstly, a reduction in the crosssectional area of the reinforcement and in its ductility results in premature bar failure. Secondly, the expansion of the corrosion products causes concrete cracking and steel–concrete bond deterioration and also affects the bending stiffness of the reinforced concrete members, causing a reduction in the overall load-bearing capacity of the reinforced concrete beams. This paper investigates the validity of a repair technique using Near Surface Mounted (NSM) carbon-fibre-reinforced polymer (CFRP) rods to restore the mechanical performance of corrosion-damaged RC beams. In the NSM technique, the CFRP rods are placed inside pre-cut grooves and are bonded to the concrete with epoxy adhesive. Experimental results were obtained on two beams: a corroded beam that had been exposed to natural corrosion for 25 years and a control beam, (both are 3 m long) repaired in bending only. Each beam was repaired with one 6-mm-diameter NSM CFRP rod. The beams were tested in a three-point bending test up to failure. Overall stiffness and crack maps were studied before and after the repair. Ultimate capacity, ductility and failure mode were also reviewed. Finally some comparisons were made between repaired and non-repaired beams in order to assess the effectiveness of the NSM technique. The experimental results showed that the NSM technique improved the overall characteristics (ultimate load capacity and stiffness) of the control and corroded beams and allowed sufficient ductility to be restored to the repaired corroded elements, thus restoring the safety margin, despite the non-classical mode of failure that occurred in the corroded beam, with the separation of the concrete cover due to corrosion products.

Keywords: carbon fibre, corrosion, strength, mechanical testing

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Authors: G. A. Rombach, A. Faron

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Crack formation and growth in reinforced concrete members are, in many cases, the cause of the collapse of technical structures. Such serious failures impair structural behavior and can also damage property and persons. An intensive investigation of the crack propagation is indispensable. Numerical methods are being developed to analyze crack growth in an element and to detect fracture failure at an early stage. For reinforced concrete components, however, further research and action are required in the analysis of shear cracks. This paper presents numerical simulations and continuum mechanical modeling of bending shear crack propagation in a three-dimensional reinforced concrete beam without transverse reinforcement. The analysis will provide a further understanding of crack growth and redistribution of inner forces in concrete members. As a numerical method to map discrete cracks, the extended finite element method (XFEM) is applied. The crack propagation is compared with the smeared crack approach using concrete damage plasticity. For validation, the crack patterns of real experiments are compared with the results of the different finite element models. The evaluation is based on single span beams under bending. With the analysis, it is possible to predict the fracture behavior of concrete members.

Keywords: concrete damage plasticity, crack propagation, extended finite element method, fracture mechanics

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Authors: Manoj Kumar, Sujata Mohanty, D. N. Rao, Arul Selvi, Sanjeev K. Bhoi

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Background: Hematopoietic progenitor cells (HPC) mobilized from bone marrow to peripheral blood has been observed in severe trauma and hemorrhagic shock patients. Granulocyte-colony stimulating factor (G-CSF) is a potent stimulator that mobilized HPC from bone marrow to peripheral blood. Objective: Our aim of the study was to investigate the serum G-CSF levels and correlate with HPC and outcome. Methods: Peripheral blood sample from 50 hemorrhagic shock patients was collected on arrival for determination of G-CSF and peripheral blood HPC (PBHPC) and compared with healthy control (n=15). Determination of serum levels of G-CSF by sandwich ELISA and PBHPC by Sysmex XE-2100. Data were categorized by age, sex, Injury Severity Score (ISS), and laboratory data was prospectively collected. Data are expressed as mean±SD and median (min, max). Results: Significantly increased the serum level of G-CSF (264.8 vs. 79.1 pg/ml) and peripheral blood HPC (0.1 vs. 0.01 %) in the T/HS patients when compared with control group. Conclusions: Our studies suggest serum G-CSF elevated in T/HS patients. The elevated in G-CSF was also associated with mobilization of HPC from BM to peripheral blood HPC. Increased the levels of G-CSF in T/HS may play a significant role in the alteration of the hematopoietic compartment.

Keywords: granulocyte colony stimulating factor, G-CSF, hematopoietic progenitor cells, HPC, trauma hemorrhagic shock, T/HS, outcome

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Authors: Samah Oda, Asmaa Khafaga, Mohammed Hashim, Asmaa Khamis

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Toxicity of hydroxyurea (HU), a treatment for certain tumors, polycythemia, and thrombocytosis, was evaluated in rats in one-month toxicity study. Sixty male albino rats were equally classified into four groups. Rats received daily oral gavage of HU in 0, 250, 500, and 750 mg/kg b.wt. Chemical and histopathological assessment of liver, lung, spleen, and bone marrow was performed at 10, 20, and 30 days of the experiment. No significant change was reported in alanine aminotransferase (ALT), aspartate aminotransferase (AST), globulin, and albumin/ globulin ratio during the experiment. Significant decreases in alkaline phosphatase (ALP) and total albumin were reported in rats received 500 and 750 mg/kg b.wt of HU. In addition, total cholesterol level increased significantly after 10 days; however, it significantly decreased after 20 and 30 days of the experiment. Moreover, hepatocytic vacuolation and necrosis with portal inflammatory infiltrates were reported along experimental periods. Pulmonary congestion, hemorrhage, interstitial mononuclear infiltration, peribronchitis, and bronchial epithelial necrosis were also reported. Severe lymphocytic necrosis in spleen and severe loss of hematopoietic cells and replacement with corresponding adipose tissue in bone marrow tissues was demonstrated. In conclusion, HU could be able to induce severe dose and time-dependent hepato-pulmonary toxicity and lymphoid depression in rats.

Keywords: hydroxyurea, hepato-pulmonary toxicity, lymphoid depression, histopathology

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Authors: Udomporn Yingpaisuk, Premwadee Karuhadej

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The purposed of this research was to study the eating habit of teenage pregnancy and its relationship to the knowledge of nutrition during pregnancy. The 100 samples were derived from simple random sampling technique of the teenage pregnancy in Bangkae District. The questionnaire was used to collect data with the reliability of 0.8. The data were analyzed by SPSS for Windows with multiple regression technique. Percentage, mean and the relationship of knowledge of eating and eating behavior were obtained. The research results revealed that their knowledge in nutrition was at the average of 4.07 and their eating habit that they mentioned most was to refrain from alcohol and caffeine at 82% and the knowledge in nutrition influenced their eating habits at 54% with the statistically significant level of 0.001.

Keywords: teenage pregnancy, knowledge of eating, eating behavior, alcohol, caffeine

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Authors: Wei Chen

Abstract:

3D concrete printing technology is a novel and highly efficient construction method that holds significant promise for advancing low-carbon initiatives within the construction industry. In contrast to traditional construction practices, 3D printing offers a manual and formwork-free approach, resulting in a transformative shift in labor requirements and fabrication techniques. This transition yields substantial reductions in carbon emissions during the construction phase, as well as decreased on-site waste generation. Furthermore, when compared to conventionally printed concrete, 3D concrete exhibits mechanical anisotropy due to its layer-by-layer construction methodology. Therefore, it becomes imperative to investigate the influence of the printing process on the mechanical properties of 3D printed strips and to optimize the mechanical characteristics of these coagulated strips. In this study, we conducted three-dimensional reconstructions of printed blocks using both circular and directional print heads, incorporating various overlap distances between strips, and employed CT scanning for comprehensive analysis. Our research focused on assessing mechanical properties and micro-pore characteristics under different loading orientations.Our findings reveal that increasing the overlap degree between strips leads to enhanced mechanical properties of the strips. However, it's noteworthy that once full overlap is achieved, further increases in the degree of coincidence do not lead to a decrease in porosity between strips. Additionally, due to its superior printing cross-sectional area, the square printing head exhibited the most favorable impact on mechanical properties.This paper aims to improve the tensile strength, tensile ductility, and bending toughness of a recently developed ‘one-part’ geopolymer for 3D concrete printing (3DCP) applications, in order to address the insufficient tensile strength and brittle fracture characteristics of geopolymer materials in 3D printing scenarios where materials are subjected to tensile stress. The effects of steel fiber content, and aspect ratio, on mechanical properties, were systematically discussed, including compressive strength, flexure strength, splitting tensile strength, uniaxial tensile strength, bending toughness, and the anisotropy of 3DP-OPGFRC, respectively. The fiber distribution in the printed samples was obtained through x-ray computed tomography (X-CT) testing. In addition, the underlying mechanisms were discussed to provide a deep understanding of the role steel fiber played in the reinforcement. The experimental results showed that the flexural strength increased by 282% to 26.1MP, and the compressive strength also reached 104.5Mpa. A high tensile ductility, appreciable bending toughness, and strain-hardening behavior can be achieved with steel fiber incorporation. In addition, it has an advantage over the OPC-based steel fiber-reinforced 3D printing materials given in the existing literature (flexural strength 15 Mpa); It is also superior to the tensile strength (<6Mpa) of current geopolymer fiber reinforcements used for 3D printing. It is anticipated that the development of this 3D printable steel fiber reinforced ‘one-part’ geopolymer will be used to meet high tensile strength requirements for printing scenarios.

Keywords: 3D printing concrete, mechanical anisotropy, micro-pore structure, printing technology

Procedia PDF Downloads 75

Authors: C. Tezara, H. Y. Lim, M. H. Yazdi, J. W. Lim, J. P. Siregar

Abstract:

Natural fibre has become an element in human lives. A lot of researchers have conducted research about natural fibre reinforced polymer. Malaysian government has spent a lot of money on the research funding for researchers and academician especially research on kenaf fibre due to exclusion of tobacco from AFTA (Asean Free Trade Area) list. This work is to investigate the mechanical properties of kenaf fiber reinforced epoxy composite where short kenaf fibre was applied and the mechanical properties of 5%, 10% and 15% wt. of kenaf fibre were added into the mixture of epoxy resin. Hand lay-up process was selected in the fabrication of the specimen for testing. The tensile, flexural and impact test were conducted following ASTM D3039, ASTM D790 and ASTM D256 accordingly. From the experiment result, the effect of different fiber loading of the specimen on its mechanical properties would be analyzed and compared in the result and discussion.

Keywords: Kenaf fibre, epoxy, composite, fibre

Procedia PDF Downloads 280

Authors: Nadia Elouaer

Abstract:

Tax revenue is the main state resource and one of the important variables in tax policy. Nevertheless, this resource is continually decreasing, so it is important to focus on the reasons for this decline. Several studies show that the taxpayer is reluctant to pay taxes, especially in countries at risk or in countries in transition, including Tunisia. This study focuses on the tax evasion behavior of a Tunisian taxpayer under the influence of his political beliefs, as well as the influence of different tax compliance variables. Using a questionnaire, a sample of 500 Tunisian taxpayers is used to examine the relationship between political beliefs and taxpayer affiliations and tax compliance variables, as well as the study of the causal link between political beliefs and fraudulent behavior. The data were examined using correlation, factor, and regression analysis and found a positive and statistically significant relationship between the different tax compliance variables and the tax evasion behavior. There is also a positive and statistically significant relationship between tax evasion and political beliefs and affiliations. The study of the relationship between political beliefs and compliance variables shows that they are closely related. The conclusion is to admit that tax evasion and political beliefs are closely linked, and the government should update its tax policy and modernize its administration in order to strengthen the credibility and disclosure of information in order to restore a relationship of trust between public authorities and the taxpayer.

Keywords: fiscal policy, political beliefs, tax evasion, taxpayer behavior

Procedia PDF Downloads 143

Authors: Doran C. Kalmin

Abstract:

The descending genicular artery (DGA) perforator free flap provides an alternative to free flap reconstruction based on a review of the literature detailing both anatomical and clinical studies. The descending genicular artery (DGA) supplies skin, muscle, tendon, and bone located around the medial aspect of the knee that has been used in several pioneering reports in reconstructing defects located in various areas throughout the body. After the success of the medial femoral condyle flap in early studies, a small number of studies have been published detailing the use of the DGA in free flap reconstruction. Despite early success in the use of the DGA flap, acceptance within the Plastic and Reconstructive Surgical community has been limited due primarily to anatomical variations of the pedicle. This literature review is aimed at detailing the progression of the DGA perforator free flap and its variations as an alternative and reliable free flap for reconstruction of composite defects with an exploration into both anatomical and clinical studies. A literature review was undertaken, and the progression of the DGA flap is explored from the early review by Acland et al. pioneering the saphenous free flap to exploring modern changes and studies of the anatomy of the DGA. An extensive review of the literature was undertaken that details the anatomy and its variations, approaches to harvesting the flap, the advantages, and disadvantages of the DGA perforator free flap as well as flap outcomes. There are 15 published clinical series of DGA perforator free flaps that incorporate cutaneous, osteoperiosteal, cartilage, osteocutaneous, osteoperiosteal and muscle, osteoperiosteal and subcutaneous and tendocutatenous. The commonest indication for using a DGA free flap was for non-union of bone, particularly that of the scaphoid whereby the medial femoral condyle could be used. In the case series, a success rate of over 90% was established, showing that these early studies have had good success with a wide range of tissue transfers. The greatest limitation is the anatomical variation of the DGA and therefore, the challenges associated with raising the flap. Despite the variation in anatomy and around 10-15% absence of the DGA, the saphenous artery can be used as well as the superior medial genicular artery if the vascular bone is required as part of the flap. Despite only a handful of anatomical and clinical studies describing the DGA perforator free flap, it ultimately provides a reliable flap that can include a variety of composite structure used for reconstruction in almost any area throughout the body. Although it has limitations, it provides a reliable option for free flap reconstruction that can routinely be performed as a single-stage procedure.

Keywords: anatomical study, clinical study, descending genicular artery, literature review, perforator free flap reconstruction

Procedia PDF Downloads 143