Wood plastic composites (WPC) are made from wood and annual plant fiber or flours, mixing with plastics materials. WPC provide better properties than resources that form it. This renewable material ...has many utilization areas because of outstanding properties such as enhanced strength, stiffness, creep, physical and mechanical properties and dimension stability. In the present work, series of filled Polypropylene (PP) composites with olive pit and almond shell flour loading (between 0-40 wt %) were prepared, to study the effect of the filler content on the mechanical, wear and friction properties of polypropylene polymer composites.
In this study, sepiolite, fly ash and apricot stone activated carbon (ASAC) were used as adsorbents for the investigation of the adsorption kinetics, isotherms and thermodynamic parameters of the ...basic dye (Astrazon Blue FGRL) from aqueous solutions at various concentrations (100–300
mg/L), adsorbent doses (3–12
g/L) and temperatures (303–323
K). The result showed that the adsorption capacity of the dye increased with increasing initial dye concentration, adsorbent dose and temperature. Three kinetic models, the pseudo-first-order, second-order, intraparticle diffusion, were used to predict the adsorption rate constants. The kinetics of adsorption of the basic dye followed pseudo-second-order kinetics. Equations were developed using the pseudo-second-order model which predicts the amount of the basic dye adsorbed at any contact time, initial dye concentration and adsorbent dose within the given range accurately. The adsorption equilibrium data obeyed Langmuir isotherm. The adsorption capacities (
Q
0) calculated from the Langmuir isotherm were 181.5
mg/g for ASAC, 155.5
mg/g for sepiolite and 128.2
mg/g for fly ash at 303
K. Thermodynamical parameters were also evaluated for the dye–adsorbent systems and revealed that the adsorption process was endothermic in nature.
Air entraining admixtures (AEA) are generally used for increasing the workability and resistance to freezing and thawing in concrete. These admixtures generate air bubbles with diameters ranging from ...10 μm to 1 mm, providing spaces for the expansion of ice, and therefore facilitate frost protection. In this study, performances of AEAs were investigated based on surface tension measurements, accounting for the effect of AEAs on surface tension. For this purpose, a new test method was developed which depends on surface tension measurements according to the Du Nouy ring method. All types of AEAs used in the scope of this research presented a substantial influence on the surface tension. It was observed that a significant relationship between the air void system and surface tension exists. The surface tension method was found as a useful tool to determine the AEA type and content to obtain the desired air void system in concrete.
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•The amount of solids inside bubbles has been quantified for different conditions.•Bubble fraction measured differs from theoretical correlations.•A novel method to determine the wake ...parameter has been developed.•The internal solids circulation has been quantified by solving the mass balance.•A sensitivity analysis confirms the need to correct for the assumptions.
The solids mass flux distribution and internal solids circulation rates in freely-bubbling gas-solid fluidized beds has been studied in detail in a pseudo-2D column. A non-invasive Particle Image Velocimetry (PIV) combined with Digital Image Analysis (DIA) technique has been further extended to investigate and quantify the gas and solids phase properties simultaneously for different particle types and sizes (all Geldart B type) at different fluidization velocities. It is found that the solids fluxes increase strongly, practically linearly, as a function of the vertical position and depend on the excess gas velocity but not on the particle size, while the most often used phenomenological two-phase fluidized bed models assume the vertical solids fluxes to be constant. To further investigate this important discrepancy, the underlying assumptions of the phenomenological models have been validated, especially concerning the average solids fraction inside the bubbles, the laterally and time-averaged axial bubble fraction profile (or visual bubble flow rate) and the wake parameter (the amount of solids carried along a bubble relative to the bubble volume). To this end, the PIV/DIA technique was further extended and a new method for the determination of the wake parameter is proposed. From the experimental results, it was concluded that i) the average solids fraction inside the bubbles is about 2.5–3% for glass beads and alumina particles and is practically independent of the excess gas velocity and particle size; ii) the measured laterally and time-averaged bubble fractions are considerably lower compared to often used correlations from literature, which would lead to a significant over-prediction of the visual bubble flow rate and iii) the wake parameter depends strongly on the bubble size and with the developed correlation the axial solids mass fluxes as a function of the vertical position can be well described. Finally, the influence of these findings was evaluated by performing a sensitivity analysis with an existing phenomenological model for fluidized beds with the new values and closures considering the case of the heterogeneously catalyzed steam methane reforming. With the developed findings and correlations the predictions with the two-phase phenomenological models can be further improved, especially concerning the hydrodynamics of the solids phase.
This study was carried out to determine the protective effects of lithium borate (LTB) on blood parameters and histopathological findings in experimentally induced acute cadmium (Cd) toxicity in ...rats. Twenty-eight male Wistar albino rats were used, weighing 200–220 g, and they were randomly divided into four groups, including one control and the following three experimental groups: a Cd group (0.025 mmol/kg), a LTB group (15 mg/kg/day orally for 5 days), and a LTB + Cd group (15 mg/kg/day orally for 5 days and Cd 0.025 mmol/kg by intraperitoneal injection on the fifth day). All the rats in the study were anesthetized with ketamine at the end of the sixth day, blood was taken from their hearts, and then the rats were decapitated. The values in the control and LTB group were usually close to each other. White blood cell (WBC), neutrophil %, and C-reactive protein (CRP) levels increased in the Cd and LTB + Cd groups while lymphocyte and monocyte levels decreased in a statistically significant manner, in comparison to the other groups. It was determined that the levels of red blood cells (RBCs), hematocrit (Htc), and hemoglobin (Hb) did not change in the groups. The levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the Cd and LTB + Cd groups significantly increased, in comparison to the other groups, while the glucose, alkaline phosphatase (ALP), albumin (ALB), and total protein (TP) levels decreased. According to histopathological findings in the control and LTB groups, the liver and kidney tissues were found to have normal histological structures. In the Cd group, severe necrotic hemorrhagic hepatitis, mild steatosis, and mononuclear cell infiltration were detected in the liver. In the LTB + Cd group, degeneration and mild mononuclear cell infiltration were found in the liver. Regarding the kidney tissue in the Cd group, severe intertubular hyperemia in both kidney cortex and medulla, as well as degeneration and necrosis in the tubulus epithelium, was observed. In the LTB + Cd group, mild interstitial hyperemia and mononuclear cell infiltration was detected. Resultantly, it can be said that LTB at this dose has non-toxic effects and some beneficial effects for liver and kidney damage caused by acute Cd toxicity.
Pre-service teacher education (PTE) is vital because adequately-prepared teachers positively add to student performance, school effectiveness, and the efficiency of an entire system of education in a ...country. This study aimed to examine the current pre-service teacher education (PTE) practices in Turkey by identifying the significant factors of pre-service teacher education to provide suggestions for the improvement of PTE. Therefore, the findings of this study will provide a reasonable basis for strengthening the quality of pre-service teacher education, which will, in turn, contribute positively to the quality of teachers. The present study is designed to examine Turkish secondary school teachers' perceptions of their preparation for the teaching profession. The sample of this study was selected by random cluster sampling as 800 teachers from 14 different cities located in seven geographical regions -- two cities in each region. AMOS 20.0 was used for the testing of the pre-service teacher education model through path analysis. Attitude towards pre-service teacher education in general, curriculum, practice, proficiency, and relevance of theory with the practice was considered as endogenous variables, and preparedness was considered as an exogenous variable. Data obtained from quantitative results have shown that teacher preparedness as a dependent factor consistently relates to independent factors that are inter-related; i.e., teaching practice has a significant impact on the relevance of teaching practice, the relevance of teaching practice has a significant impact on proficiency and proficiency has a significant impact on curriculum, and curriculum has a significant impact on PTE in general. Future research would be conducted on the factors affecting the in-service teacher training programs.
Abstract Background It is thought that airway inflammation is more common in obese asthmatic patients because inflammation is harder to control and does not respond well to glucocorticoid treatment. ...Objective This study's aim was to investigate the effect of obesity on airway and systemic inflammation in children with asthma and to identify the biomarkers that play a role in this inflammation. Methods The study included patients aged 6–16 years who were diagnosed with asthma in the paediatric allergy outpatient clinic of Bagcilar Training and Research Hospital in Turkey. Complete blood count parameters were compared between three groups: obese asthmatic ( n = 43), obese non-asthmatic ( n = 45), and non-obese non-asthmatic (control group, n = 30). Levels of high-sensitive CRP (hs-CRP), neutrophil gelatinase-associated lipocalin (NGAL), osteopontin (OPN), and matrix metalloproteinase-9 (MMP-9), and 25(OH)-vitamin D were compared between the groups. Results No statistically significant differences were observed in 25(OH)-vitamin D, NGAL, OPN, hs-CRP, and MMP-9 levels between groups. There was a statistically significant negative correlation between FEV1/FVC and NGAL and MMP-9. Conclusion This is the first study to investigate levels of hs-CRP, NGAL, OPN, MMP-9, and 25(OH)-vitamin D in obese asthmatic children. Larger studies with sputum and BAL examinations are required to determine the potential of biomarkers for identifying inflammation in obese asthmatic children.
The main goal of this study is to obtain an optimum mix design for steel-fibre-reinforced concrete (SFRC) plates that establishes the optimum aspect ratio (length/diameter) and volume fraction of ...fibres by maximising the plate toughness (as specified by the EFNARC standard) and minimising the mix costs. To achieve this goal, 60 plate specimens with dimensions of 600 × 600 × 100 mm were produced based on different SFRC mixtures and tested. The compressive and splitting tensile strengths and the elastic modulus of the mixtures were also determined. Based on the experimental results, a multi-objective simultaneous optimisation technique was used to determine the optimum SFRC mix design. The variables considered during optimisation were the aspect ratio and volume fraction of the fibres for two different concrete classes. For each concrete class, the optimum mix design was determined.
The objective of this research is to optimise the fracture parameters of steel fibre reinforced concretes to obtain a more ductile behaviour than that of plain concrete. The effects of the aspect ...ratio (
L/
d) and volume fraction of steel fibre (
V
f) on fracture properties of concrete in bending were investigated by measuring the fracture energy (
G
F) and characteristic length (
l
ch). For optimisation, three-level full factorial experimental design and response surface method were used. The results show that the effects of fibre volume fraction and aspect ratio on fracture energy and characteristic length are very significant.
The main objective of this study is to provide more data on the effects of expanded perlite on the mechanical properties and thermal conductivity of lightweight concrete. In the experimental program, ...mixtures were prepared by partially replacing natural aggregate by expanded perlite and as a result, unit weights of lightweight concretes in fresh state varied between 700 and 2000
kg/m
3. Water to cement ratio was kept constant in all mixtures. Compressive strength, modulus of elasticity, water absorption and capillarity coefficient of the mixtures were determined. Thermal conductivity of the specimens was also obtained. Test results show that the compressive strength and modulus of elasticity decreases with increasing in perlite content. Water absorption and sorptivity coefficient, however, increase with the higher perlite contents. The test results indicate that the thermal conductivity is substantially improved with the use of perlite and a strong relationship between thermal conductivity and unit weight is obtained.
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