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Assessment on engineering properties and CO2 emissions of recycled aggregate concrete incorporating waste products as supplements to Portland cement
No full textThis paper presents an experimental investigation on the durability properties and carbon dioxide (CO 2 ) emissions of concrete developed using waste products. The concrete comprised of recycled concrete aggregate (RA) as a complete coarse aggregate replacement. In addition, rice husk ash (RHA), palm oil fuel ash (POFA) and palm oil clinker powder (POCP) were used as replacement materials for cement at levels up to 30%. The supplementary cementitious materials (SCMs) were used in RA concrete with the aim of reducing the dependency on cement as a stand-alone binder. The compressive strength, water absorption, chloride-ion penetration and electrical resistivity were investigated for RA concrete containing SCMs. Moreover, the residual compressive strength was also examined along with the weight loss to check the elevated temperature resistance of RA concrete with SCMs. The results revealed that the use of 30% RHA as SCM produced the highest compressive strength efficiency of 0.143 MPa/kg cement among all mixes at the age of 90 days. In addition, a significant enhancement was observed for the durability-related properties at later ages, although the engineering properties of RA concrete containing SCMs was low at the age of 28 days. The thermogravimetric (TG) analysis indicated that the RHA is more effective as a pozzolanic additive than POFA and POCP. The CO 2 emissions from RA concrete were reduced by approximately 29% when it was incorporated with 30% SCM, where the eco-strength efficiency showed the highest values at 20% cement replacement level of 20%
Physical measurement of the expansion rate of anisotropic tissue expander in the skin of the horse
No full textTissue expansion technique is one of the most important innovations in skin reconstructive surgery. In this study, anisotropic self-inflating hydrogel tissue expanders were implanted subcutaneously at different anatomical locations; frontal, right shoulder and right forelimb of horses. The resulting skin expansion were observed and recorded daily for the duration of 28 days by manual physical measurements. The rate of height growth and swelling that were recorded are 164.25% at the frontal region of the head, 189.13% at the shoulder region and 122.42% at the forelimb region. The growth of the tissue expander in the three sites could be summarized in three phases; biodegradable in week one, the peak of anisotropic expansion in week two and three, and final degree of swelling in week four
Surface Decoration of Selenium Nanoparticles by Proteins from the Culinary-Medicinal Shiitake Mushroom, Lentinus edodes (Agaricomycetes), for Enhanced Fibrinolytic Activity
No full textLentinus edodes (shiitake mushroom) has exhibited fibrinolytic activity. We synthesized and characterized selenium nanoparticles (SeNPs) using protein precipitated from the mushroom. We also investigated the fibrinolytic activity of the SeNPs. The proteins from a crude extract of L. edodes were recovered through the use of aqueous 2-phase separation, and these we used as the capping agent in SeNP biosynthesis. We characterized the SeNPs using UV-visible spectrophotometry, field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), transmission electron microscopy (TEM), particle size distribution analysis, and Fourier transform infrared spectroscopy (FT-IR). The fibrinolytic capability of the SeNPs was tested through an in vitro fibrin plate assay. The UV-visible spectra showed maximal absorbance at 220 nm. FESEM images showed that the SeNPs were dispersed and did not clump. The TEM images revealed a spherical shape and average size of the SeNPs. The particle size distribution analysis confirmed the mean size of the SeNPs at 64.53 nm. A strong signal for the presence of selenium was observed in the EDX analysis. The FT-IR spectrum revealed the involvement of protein functional groups in the reduction of sel-enite. Overall, the SeNPs capped with protein from shiitake mushroom were effective as an in vitro fibrinolytic agent
Assessment of toxic metals in water and sediment of Pasur River in Bangladesh
No full textThis study was conducted to assess the levels of toxic metals like arsenic (As), chromium (Cr), cadmium (Cd), and lead (Pb) in water and sediments of the Pasur River in Bangladesh. The ranges of Cr, As, Cd, Pb in water were 25.76-77.39, 2.76-16.73, 0.42-2.98 and 12.69-42.67 μg/L and in sediments were 20.67-83.70, 3.15-19.97, 0.39-3.17 and 7.34-55.32 mg/kg. The level of studied metals in water samples exceeded the safe limits of drinking water, indicating that water from this river is not safe for drinking and cooking. Certain indices, including pollution load index (PLI) and contamination factor (Ci f) were used to assess the ecological risk. The PLI indicated progressive deterioration of sediments by the studied metals. Potential ecological risks of metals in sediment indicated low to considerable risk. However, the Ci f values of Cd ranged from 0.86 to 8.37 revealed that the examined sediments were strongly impacted by Cd. Considering the severity of potential ecological risk (PER) for single metal (Ei r), the descending order of contaminants was Cd >Pb> As> Cr. According the results, some treatment scheme must formulate and implement by the researchers and related management organizations to save the Pasur River from metals contamination
Stirrer time effect on optical properties of nanophotonic LiNbO3
No full textLithium niobate (LiNbO3) nanostructures are synthesized on n-silicon substrate by spin coating technique with stirrer times; 8 h, 24 h and 48 h. LiNbO3 is characterized and analyzed by Scanning Electron Microscope (SEM), Atomic Force Microscopy (AFM), X-ray diffraction (XRD) and UV-visible and Photoluminescence (PL). The measurements show that as stirrer time increases, the structures start to crystallize to become more regular distribution, which helps to apply in optical waveguides. In addition, the calculated refractive index and optical dielectric constant are in agreement with experimental data
Thermal conductivity and viscosity models of metallic oxides nanofluids
No full textFor over ten years, investigators focused on determining and modelling the effective thermal conductivity and viscosity of nanofluids. Lately, many theoretical and experimental investigations on convective heat transfer have been performed on the augmentation of heat transfer by utilizing suspensions of nanometer-sized solid particle materials (metallic or nonmetallic) in base fluids. The main purpose of this work is to determine the thermal conductivity and viscosity of various types of metallic oxides (Al 2 O 3 , CuO, SiO 2 and ZnO) for nanoparticle concentrations of 1–5 vol% at temperatures of 300–320 K and nanoparticle shapes (blades, platelets, cylindrical, bricks, and spherical). The results illustrate that the effective thermal conductivity and thermal conductivity ratio of metallic oxide nanofluids increase with temperature and nanoparticles volume fraction but decreases nanoparticle size intensifies. Besides that, the results of effective viscosity and viscosity ratio obtained indicate a considerable rise with the increase of nanoparticles concentration. Thus, optimum nanoparticle concentration is essential to be determined in forming nanofluids that can enhance thermal systems performance. Finally, it is found that nanoparticles shape has great impact on the thermophysical properties of nanofluids
Effect of aged crumb rubber bitumen on performance dense graded mix in Malaysia
No full textTo prevent pavement failure there are different solutions such as adopting new mix methods or utilization of waste materials as additives. The main objective of this study is to evaluate the effect of crumb rubber (CR) added to bitumen binder as a reinforcing material on dense graded asphalt (DGA) mixture performance. The performances of the DGA mixture were investigated by means of Marshall Stability and flow test, stiffness test, indirect tensile strength test and cantabro test on DGA samples before and after exposing unmodified and modified binders to aging process. In this study, bitumen PEN (60/70) was utilized, modified with CR at three various modification levels, namely, 5%, 10%, and 15%, respectively, by weight of the asphalt binder. The optimum content of the added CR was found to be 5-10%. This percentage results in the best level of stability and stiffness, maximum indirect tensile strength and lower flow. The modified samples at different of CR contents were obviously better properties in comparison with that of unmodified samples. It could be concluded that reinforcement of binders by CR is a successful and beneficial technique
Sensorless control system for assistive robotic ankle-foot
No full textThis article presents a novel sensorless control system of assistive robotic ankle-foot prosthesis, two estimation algorithms were developed and an analogy between them has been made. The system actuator’s motor is a permanent magnet synchronous motor, unlike other powered ankle-foot, where the brushless DC motor and DC motor were used. Utilizing the permanent magnet synchronous motor will reduce the torque ripples and increase system ability to be overloaded compared to systems which utilize the brushless DC motor. Moreover, the ability of the machine to operate in all speed range makes this machine more suitable for the application. Both estimation algorithms are built using C-code and assessed in MATLAB Simulink. The estimation algorithms are used to provide motor and powered ankle-foot’s angular speed and position. Two-level control system is used to evaluate the estimation algorithms; the control system role is to mimic biological ankle-foot performance during normal ground level walking speed. Based on the result of this article the unscented Kalman filter (UKF) is applicable for the application, as a result of the observer ability to estimate the motor load and angular position. On the other hand, extended Kalman filter (EKF) accuracy is affected by the load applied to the motor. Furthermore, the angular position is evaluated by integration of the angular speed which means integration of angular speed estimation error
Enhanced amperometric detection of paracetamol by immobilized cobalt ion on functionalized MWCNTs - Chitosan thin film
No full textIn the present study, a nanocomposite of f-MWCNTs-chitosan-Co was prepared by the immobilization of Co(II) on f-MWCNTs-chitosan by a self-assembly method and used for the quantitative determination of paracetamol (PR). The composite was characterized by field emission scanning electron microscopy (FESEM) and energy dispersive x-ray analysis (EDX). The electroactivity of cobalt immobilized on f-MWCNTs-chitosan was assessed during the electro-oxidation of paracetamol. The prepared GCE modified f-MWCNTs/CTS-Co showed strong electrocatalytic activity towards the oxidation of PR. The electrochemical performances were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). Under favorable experimental conditions, differential pulse voltammetry showed a linear dynamic range between 0.1 and 400 μmol L−1 with a detection limit of 0.01 μmol L−1 for the PR solution. The fabricated sensor exhibited significant selectivity towards PR detection. The fabricated sensor was successfully applied for the determination of PR in commercial tablets and human serum sample
Treatment of chronic back pain using indirect vibroacoustic therapy: A pilot study
No full textBACKGROUND: Low frequency sound wave stimulation therapy has become increasingly popular in the rehabilitation fields,due to its ease, less fatiguing and time efficient application.OBJECTIVE: This 12-week pilot study examines the efficacy of applying low frequency sound wave stimulation (between16-160 Hz) through both hands and feet on relieving pain and improving functional ability in patients with chronic back pain.METHODS: Twenty-three participants with chronic shoulder (eleven participants) or low back pain (twelve participants) underwent a 12-week vibration therapy program of three sessions per week. A low frequency sound wave device comprising fourpiezoelectric vibration-type tactile tranducers enclosed in separate 5-cm diameter circular plates, which generate sinusoidal vibratory stimuli at a frequency of 16-160 Hz, was used in this study. Primary outcome measure was pain sensation measuredusing the Visual Analogue Scale (P-VAS). The secondary outcome measures were pain-related disability measured using thepain disability index (PDI) and quality of life measured using the SF-12.RESULTS: At week 12, significant reductions in pain sensation and pain-related disability were observed, with mean reductionsof 3.5 points in P-VAS and 13.5 points in the PDI scores. Sixty-five percent of the participants had a reduction of at least 3 pointson the P-VAS score, while 52% participants showed a decrease of at least 10 points in the PDI score. Significant improvementwas observed in the SF-12 physical composite score but not the mental composite score.CONCLUSIONS: The preliminary findings showed that passive application of low frequency sound wave stimulation therapythrough both hands and feet was effective in alleviating pain and improving functional ability in patients with chronic back pain