ABSTRACTFive novel transition metal coordination polymers (CPs) or commonly called as CPs based on chelating ligand 1-(2, 4-dihydroxy-5-(1-(hydroxyamino)ethyl)-3-bromophenyl) ethanoneoxime (DHBO) (...
The temperature rise in chips during machining process largely affects the tool life as well as the quality of the machined product. It also affects the power required for machining. Therefore, accurate measurement of temperature rise in chips during machining is important not only to understand and predict any changes in the properties of the component but also to predict and optimize the life cycle of the tool. In this work, we measure temperature rise during shaping process of the aluminum block using thermal imaging technique and compare the values with that obtained using Weiner’s model for moving heat source. Our result indicates that temperature value obtained by the infrared camera was very close to those obtained by Weiner model. This work validates the use of Weiner model for an in situ temperature rise of chips during machining.
The compound (I) was synthesized and characterized by elemental analysis, Fourier-Transform InfraredSpectroscopy (FT-IR), UV-VIS, X-ray, 1H Nuclear Magnetic Resonance Spectroscopy (NMR) and 13C NMR spectroscopic and analytic techniques. Both the highest occupied molecular orbital and lowest occupied molecular orbital values of this compound were calculated by the GAUSSIAN G03 software program. The crystal structure of I was determined by the single crystal X-ray diffraction method. The molecular structure is stabilized by intermolecular C—H…O hydrogen bonds, C—H…π interactions and π–π stacking interactions. According to FT-IR and X-ray diffraction method data, compound (I) exists in the tautomeric form I in the crystalline state. In accordance with UV-VIS and 1H NMR's data, the structure of the ketoamine–enolimine (form I and II) of compound (I) was in equilibrium in dimethyl sulfoxide (DMSO)solution. The antibacterial activity of compound was investigated against bacteria and fungus. Moreover, the catalytic activity of this compound was tested in the carbon–carbon coupling reaction.
AbstractThis study reports on novel polyacrylonitrile/polyethylenimine (PAN/PEI) blend, polyacrylonitrile/polyethylenimine/carbon nano-onion (PAN/PEI/CNO) nanocomposite and related PAN/PEI/CNO foam...
Demineralization of Enugu Coal with HCl, H2S04, HN03, HF and H3P04 under different conditions such as leaching time, particle size, acid concentration and leachant volume was investigated in this study. The filtrate from each treatment was analyzed with Atomic Absorption X-ray Spectrophotometer (AAS) to determine the amount of metals (Pb, Cr, Cd, Ar, and Hg) leached. Similarly, the residual coal from each treated sample was also analyzed together with virgin coal using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectrophotometer (EDAX), X-ray Fluorescence (XRF), and Fourier Transform Infrared Spectrophotometer (FTIR). Lithophiles like aluminum and silicates revealed by EDAX and Micrograph of virgin coal was found to be absent in residual coal, which is an indication of demineralization. Proximate analysis of coal ash after acid treatments showed that the ash content decreased with increase in acid concentration. XRF results showed that SiO2, Al2O3, and Fe2O3 are the dominant minerals in coal ash. Statistical analysis atP<0.05 showed that leaching leaching of trace elements depend on the leaching time, acid type, acid concentration, particle size and leachant volume. Results of the investigation revealed that HNO3 mostly influenced the removal of trace elements from Enugu coal.
The graphene quantum dots (GQDs) with outstanding electron conductivity and good optical properties modified Ag3PO4 composites were prepared by a simple two-step method. Compared to pure Ag3PO4, the GQDs/Ag3PO4 composites exhibited enhanced photocatalytic activities for degradation Rhodamine B (RhB) and 4-Chlorophenol (4-CP) under the visible-light irradiation. More interestingly, the stabilities of Ag3PO4 were also been improved after introducing GQDs. The possible reaction mechanism was proposed by discussing comprehensive characterizations, which indicated that the GQDs can work as electron acceptors to enhance separation efficiency of photogenerated electron-hole pairs. The structure-activity relationships have been studied in detail. The active species was determined and photocatalytic mechanism was proposed.
Kinetic degradation of organic matter was investigated in this work by composting mixtures of organic wastes with bulking agent (sawdust) to produce biofertilizer. In-vessel method of composting was performed with three plastic drums each of 120 L capacity. Temperature, microbial population, and pH were used to monitor the rate of organic matter degradation during composting. Turning over of the compost piles was done twice every week for aeration. Various physical, chemical, and biological parameters were monitored at every 5 days interval till the end of composting. The organic matter degradation data was used to determine the kinetic parameters according to the four kinetic models; Petric and Selimbasic, Michaelis menten, Contois, and Xi et al. model. Physiochemical properties of the compost extracts demonstrated that Organic matter and Carbon content decreased significantly with time in all the compost, nitrogen content of the composts increased significantly except in the control. The highest average temperature reached during the composting process was 61.4°C after 20 days of composting of substrates in compost 2. Error analysis conducted on the models showed that Xi et al. model best described the degradation of organic matter during composting.
This work focuses on the optimisation of key process parameters of Colocynthis vulgaris Shrad seed oil extraction using response surface methodology. The effects of temperature, particle size and time on the oil yield were evaluated. The process fitted (R2 = 99.25%) to second-order quadratic model, while linear and quadratic terms of the process variables were significant (p > 0.05) on the oil yield. At optimum process, parameters of 55 °C, 0.5 mm and 150 min, 53.86% oil yield were obtained. The oil colour, viscosity, acidity, moisture content, iodine value, peroxide value, saponification value and flash point were yellow, 7.64 Cp, 1.66 mg KOH/g oil, 0.78%, 112.53 g/I2/100g oil, 6.82 M/mol/kg, 193.61 mg KOH/g and 230 °C, respectively. Unsaturated and saturated fatty acids of the oil were 61.89% and 37.99%, respectively. Physiochemical properties of the oil showed its potential application industrially.
Molecular modelling and computational approaches were used to design (virtual) molecularly imprinted binding sited for 170 amino acids, dipeptides and tripeptides. Analysis of the binding energy of ligands to their corresponding virtual binding sites revealed a direct correlation between size of the ligand and its binding affinity. Only tripeptides were capable of forming binding sites in molecularly imprinted polymers (MIPs) that are capable, in theory, of binding the corresponding targets at micromolar concentrations. No appreciable specificity was demonstrated in binding of virtual binding sites and corresponding templates. It is possible to conclude that although tripeptide sequences are sufficiently long to form MIPs with relatively high affinity, the sequence of peptide epitopes should be substantially longer that three amino acid residues to ensure specificity of imprinted sites. This consideration will be useful for the design of highly efficient MIPs for proteins.
Steel structures and pipelines can be saved from environmental effects by epoxy based coating. This research has been focused to reinforce locally developed nanoparticles of silica sand in epoxy ba...
Thin films of ruthenium (Ru) on 6-hexagonal silicon carbide (6H-SiC) and 4-hexagonal silicon carbide (4H-SiC) were analysed by Rutherford backscattering spectroscopy (RBS) at various annealing temperatures in the air-ambient. RBS analysis indicated Ru oxidation at a temperature of 400 °C and commencement of diffusion of Ru into SiC at a temperature of 500 °C for both Ru–4H-SiC and Ru–6H-SiC. X-ray diffraction analysis of samples annealed in air at 600 °C showed evidence of formation of ruthenium silicide in both 4H and 6H-SiC. Silicide formation in 4H-SiC and Ru oxidation in 6H-SiC were also confirmed by Raman analysis. Both samples of Ru–6H-SiC and Ru–4H-SiC Schottky barrier diodes (SBD) showed excellent rectification behaviour and linear capacitance-voltage characteristics up to an annealing temperature of 600 °C for 6H-SiC and 300 °C for 4H-SiC . The Ru–6H-SiC and Ru–4H-SiC SBDs degraded after annealing at 700 °C and 400 °C, respectively as evidenced by the appearance of infinite series resistance. The degradation of Ru–6H-SiC may be attributed to the inter-diffusion of Ru and Si at the Schottky-substrate interface, while the oxidation of Ru which led to the formation of of non-conducting and gaseous oxide compounds is the likely cause of Ru–4H-SiC SBDs device failure.
H2S is considered as a lethal ‘gas of rotten eggs,’ and recognized for hundreds of years as a toxicant. The gas can be harmful even if present as low as 0.05 ppm. The increase in its concen...
The effects of process parameters (temperature, time and particle size) on the oil yield as well as their effects on the kinetic and thermodynamic (enthalpy, entropy and free energy) parameters of oil extraction from Colocynthis vulgaris Shrad [melon seed (MS)] were investigated. The highest oil yield of 53.86% (by weight) was obtained at 55 °C, 0.5 mm and 150 min. Results of the physicochemical properties indicated that the viscosity, acidity and flash point were 7.64 Cp, 1.66 mg KOH/g oil and 230 °C, respectively, indicating the potential industrial utilisation of the oil. Chemical composition analysis of MS oil showed that it is composed of 61.89% and 37.99% unsaturated and saturated fatty acids, respectively. The kinetics of MS oil extraction was best described by pseudo second-order model, followed by hyperbolic, Elovich's and parabolic models. However, the power law model failed to give adequate fitting to the experimental data. ΔH, ΔS and ΔG values of the MS oil extraction process were 333.40 kJ/mol, 1.22 J/mol/K and −64.82 kJ/mol, respectively, indicating an endothermic, irreversible and spontaneous process.
Carbon monoxide (CO) is an important gaseous biomolecule known to possess manifold biological relevance. The molecule is co-classified as ‘gasotransmitters’ along with nitric oxide produced by metalloproteins in human beings. In conspicuous interests towards design and synthesis of carbon monoxide releasing molecule (CORM), herein Ru(II) carbonyl complex studied under a combined experimental-theoretical approach is reported. The representative complex includes a novel ruthenium hydride carbonyl complex of 2-benzoylpyridine. Elemental analysis, decomposition temperature measurement, cyclic voltammetry, Fourier-transform infrared spectroscopy (FT-IR) and UV-visible spectral techniques were used to characterize the complex. A special focus was given towards the computational prediction of CO releasing ability and thermodynamic evaluation. Moreover, cell toxicity against COLO-205 (human colon derived-ATCC code 205) human cancer cell line has also been implicated in the current report.
A perovskite sample of a chemical formula Ca0.8Ba0.2Cu3Ti4O12 (CBCTO-20) ceramic has been fabricated by a low-cost ceramic technology. The structural analysis reveals that the studied compound has cubic crystal symmetry at room temperature. The surface micrograph of the pellet sample, recorded at room temperature using scanning electron microscope (SEM), shows a high-density sample. Attempts have been made to study the (a) effect of microstructures containing grains, grain boundaries, and electrodes in impedance and capacitive characteristics, (b) relationship between structural–physical properties and (c) nature of the relaxation mechanism of the prepared samples. The electrical behavior of the sample is analyzed by using complex impedance and modulus data. (P ∼ E) loop of the CBCTO bulk sample showed lossy behavior. The utilization of TiO2 and CuO2 nano-size powder at the beginning stage with micron size CaCO3 and BaCO3 powder promote the kinetics of rapid solid-state reaction at the microscopic level. This compound shows a remarkable temperature stable relative dielectric properties and low tangent loss, thus becoming a potential candidate for high-temperature dielectric applications.
The polycrystalline samples having chemical formula 0.7(BiGdxFe1−xO3)−0.3(PbTiO3) (x = 0.0, 0.05, 0.10, 0.15 and 0.20) were fabricated by using high temperature mixed oxide route. The X-ray diffraction spectra suggested rhombohedral (major) symmetry with small impurity phases. The surface microstructure showed a highly dense packing of grains throughout the wider area for all samples. The dielectric permittivity and loss factor of all samples were studied with the help of temperature-dependent dielectric parameters. The relaxation mechanism was suggested from the dielectric and impedance spectroscopy. The conduction mechanism of all samples was investigated. The P–E and M–H loops of all the samples were taken at room temperature showing the multiferroic properties.
Designing new eco-friendly fibers enable the creation of an alternative resource for many applications, specifically within the field of polymeric composites. This article details the fabrication o...
Banana peduncle fibres (BPF) are new natural fibres that need the attention of researcher. In this study, the effect of chemical treatments on the BPF for possible application in polymer composites production was investigated. Alkali, acetic anhydride, permanganate and silane treatment of BPF were studied. Tensile test and microstructure were used to validate the work. The obtained results shows that alkali treatment fibres have tensile strength of 98.33 N/mm2 and untreated fibre strength of 51.62 N/mm2, acetic anhydride treatment of the BPF have a maximum tensile strength 108.61 N/mm2 at 2 h. Permanganate treatment of BPF maximum strength of 118.89 N/mm2 at the 2 h. The celluloses content of the BPF was enhance from 63.40, 75.81, 82.23, 77.78 and 79.67% for the untreated BPF, alkali, silane, KMnO4 and acetylation treatment. It was established that silane treatment has the best tensile strength after treatment of the BPF.
In recent years, the development of natural and synthetic fibers reinforced hybrid composites is one of the high attractive research fields. These composites are one of the major concerns for many industrial applications due to weight reduction and ecological reasons. In this experimental study, partially eco-friendly hybrid composites were fabricated by using carbon and flax fibers with epoxy resin. The composites were fabricated by hand lay-up process and the properties such as inter-laminar shear strength (ILSS), Fourier transform infra-red (FTIR) spectroscopy analysis, hardness, wear behavior and weight gain characteristics have been carried out. The internal structures of the fractured surfaces of the tested composites were analyzed using a scanning electron microscopy (SEM) analysis. From the experimental results, it is observed that the average weight loss is 17.98%, ILSS varies between 3.96 and 4.9 MPa and hardness is in the range of 62.33–77.66 (HRC). The results further revealed that the percentage of water intake of the flax fiber is 92%, carbon fiber is 36.6% and these fibers reinforced composite is 61.9%. From the results, it is concluded that the above said properties are comparable with pure carbon fiber reinforced composites, which shows the potential for hybridization of flax fiber with carbon fiber.
A prediction model for the throughput capacity and energy consumption of cassava tuber-shredder was developed following fundamental principles and iterative steps involved in machine process modelling. The homogeneity of each of the derived model was verified using dimensional analysis, after which, the validation and confirmation of the adequacies of the developed models were performed using six experimental runs. Each model's prediction accuracy is over 98% with the range of the standard error for the specific energy consumption of the machine found to be −1.48 to 1.49%, while that of throughput of the machine was found to be −1.21 to 1.31% respectively. The result of the verification showed R2 value of 99.86% for the throughput capacity and 99.99% for specific energy consumption. This shows a good fit with a positive linear relationship between the observed and the predicted values for the two parameters predicted. The performance efficiency of the modelled cassava shredder ranged from 84 to 85.11% at a shredding speed of 300–600 rpm. It was observed from the ANOVA table that the shredding speed significantly affected the specific energy consumption and throughput but not the shredding efficiency.
