Table of Contents - Volume 18 Number 3

Concrete is highly used construction material with cement being its major ingredient. Also, the demand for good quality of concrete is increasing because of the fast-growing urbanization. But there are certain problems associated with the manufacturing of cement. One of the major problems being production of carbon dioxide causing pollution in environment, the manufacturing of cement is quite expensive and it also leads to the depletion of resources. In order to curtail the consumption of cement, it has become inevitable to replace cement by certain amount with substituent materials that are cheaper to produce in order to lower down the financial cost of concrete production by some extent. The review paper, elaborates many properties of concrete by the inclusion of Kota stone slurry after evaluating several research papers. The following paper discusses numerous properties of concrete including workability, compressive strength, split tensile strength, water absorption and modulus of elasticity. The paper demonstrates that when used appropriately, inclusion of Kota stone slurry in concrete had a positive impact on concrete by increasing the strength and durability.

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This work presents design and fabrication of efficient and economical ultrasonic utensil cleaning machine. Electrical energy is converted into Mechanical energy by transducer. Transducer vibrates with ultrasonic frequency supplied to it by the frequency producer. These vibrations produce cavitation bubbles in the solvent/water. The size of the bubbles is in micron range. The mass of the cavitation bubbles depend on the rate of recurrence of the transducer. These bubbles act as scrubber which scrub the surface of utensil thus removing the soils/dirt stick on it. The size of the bubble is so small it does not cause any damage to the surface of utensil. Higher the frequency, more homogeneous will be the cleaning. Rinsing is provided within the system which will make it more compact. To keep the contaminants away from the cleaned surface, sweep frequency is used. Rotation to the basket is given by the motor. This rotation helps to reduce the cycle time and also dry the surface of utensil by centrifugal action. So when the utensil is removed from the basket it is ready for use. By this technology cycle time will be reduced drastically. Without any human efforts it can clean the dirtiest stains from the oily utensils. All types of utensils can be cleaned whether it is ceramics, glass, copper, wood, aluminum, stainless steel, etc. This cleaning process is more hygienic and can clean more efficiently compared to conventional cleaning.

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This paper reports the analyses carried out with the company Pedrini SpA ad unico socio, located in Carobbio degli Angeli, Bergamo (IT). Wire ropes with diamond beads, used as cutting tools in multi-wire machines for cutting blocks of stone, were considered and a failure analysis of the wire ropes was carried out. The aim of the paper is to highlight the damage mechanisms of the wire ropes to increase service life of these cutting tools. Microscope observations and the penetrating liquids method were used to analyze the damaged wire ropes. Fatigue, corrosion and contact fatigue problems were observed and the effect of the centering of the beads on the wire rope was studied.

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In the present investigation we have fabricated the cerium dioxide (CeO2) nanoparticles by green route. While preparing the cerium dioxide nanoparticles by co-precipitation method, Neem leaf extract mixed into the precursor of cerium. The synthesized nanoparticles of CeO2 were used for the preparation of thick film sensor by using screen printing strategy. The fabricated CeO2 sensor was characterized by XRD, SEM, EDS and TEM techniques. The structural characteristics investigated by x-ray diffraction technique (XRD). XRD confirms the formation of cubic lattice of CeO2 material. The surface, texture, porosity characteristics were investigated from SEM analysis, while chemical composition of the material was analysed by EDS technique. The transmission electron microscopy (TEM) confirms the formation cubic lattice of the cerium dioxide material. The thickness of the films was calculated from mass difference method, the prepared film sensors belong to thick region. The fabricated material CeO2 sensor was applied as gas sensor to sense the gases such as LPG, petrol vapors (PV), toluene vapors (TV) and CO2. The CeO2 sensor showed excellent gas response for LPG and PV, nearly 93.20 % and 78.23 % gas response. The rapid response and recovery of the prepared sensors was observed at the tested gases. CeO2 material also employed for antibacterial study at several pathogenic organism such as pseudomonas, staphylococcus aureus and salmonella typhae. From antibacterial study it was observed that the material is capable of inhibiting the growth of these pathogenic microbes.

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The available literature and research work on W-type hexaferrites is mainly focused on Co- and Zn-based calcium W-type hexagonal ferrites with a variety of cationic substitutions. The Modifications in the properties of the Calcium W-type ferrite based on Ni²⁺ as the divalent metal ion, however, is not studied sufficiently in the research literature vailable. In this study, the focus is mainly on the effects of substitution of Ni²⁺ on the properties of CaCo₂W exaferrites. The investigations carried out are mainly XRD, SEM and VSM. The main objective of this research investigation is to study the effect of substitution of Nickel and Cobalt on the structural and magnetic properties of calcium W-type hexaferrite CaCo_2-xNi_xFe₁₆O₂₇ (x=0, 1 and 2). XRD analysis and characterization revealed slight decrease in the values of lattice constants ‘a’ and ‘c’ with increase in concentration ‘x’. The particle size was confirmed from SEM and TEM images. The analysis of VSM for magnetic properties reveals decrease in coercivity and increase in the values of saturation magnetization as concentration increases. The results of measurements made bythe various experimental techniques and the observations were compared to understand the crystalline and magnetic structure of the compounds

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The present study focuses on an efficient eco-friendly method for reducing graphene oxide (rGO) using Coffea arabica leaf extract for bio-medical applications for the first time to the best of our knowledge. The reduction of graphene oxide (GO) using Coffea arabica leaves was verified through Raman, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM). The XRD peaks corresponding to GO at 2 =10º have dissapeared on reduction of GO to rGO and the formation of rGO was verified through a new broad peak at 2 =26º. FTIR revealed functional group changes in reducing GO to rGO. The SEM images of rGO showed a ribbed form instead of the rigid appearance of the GO flakes. The analysis revealed that the current green method is a feasible method for reducing GO to rGO and formation of the Coffea arabica/rGO nanocomposite. The composite prepared from young coffee leave exhibited higher antioxidant capacity than matured leave against scavenging 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radicals. Fascinatingly, the Coffea arabica/rGO nanocomposite showed an anti-inflammatory activity as well suggesting that the Coffea arabica /rGO nanocomposite is promising candidate for bio-medical applications in near future.

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Hardness in drinking water is a major problem in domestic usage. It is important to use drinking water within the tolerance limits of hardness. Clay samples obtained from two different areas in Sri Lanka were analysed, modified, and optimized with a view to suppress the hardness in drinking water. Characterization of clay was carried out using XRD (X-ray diffraction spectroscopy), FTIR (Fourier transformed infrared spectroscopy), and SEM (Scanning electron microscope). Variation of the adsorption capacity of clay was analysed at different firing temperatures of the clay samples. XRD analysis revealed that both clay types are consisting of Kaolinite as the main constituent. The hardness adsorption efficiency and the retention of hardness adsorption in prolonged cycles has been observed when the clay is heated at different temperatures. In addition, the water hardness adsorption efficiency was enhanced by the cationic modification using sodium chloride. The results further reveals that the Freundlich isotherm is best fit for Ca2+ adsorption on both Biyagama and Deniyaya clay whereas that for the Mg2+ adsorption is Langmuir isotherm. The present study is useful to develop low-cost clay-based materials to minimize water hardness.

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