Fabrication,characterization, and thermal property evaluation of silver nanofluids

Silver nanoparticles were successfully prepared in two different solvents using a microwave heating technique, with various irradiation times. The silver nanoparticles were dispersed in polar liquids (distilled water and ethylene glycol) without any other reducing agent, in the presence of the stabilizer polyvinylpyrrolidone (PVP). The optical properties, thermal properties, and morphology of the synthesized silver particles were characterized using ultraviolet-visible spectroscopy, photopyroelectric technique, and transmission electron microscopy. It was found that for the both solvents, the effect of microwave irradiation was mainly on the particles distribution, rather than the size, which enabled to make stable and homogeneous silver nanofluids. The individual spherical nanostructure of self-assembled nanoparticles has been formed during microwave irradiation. Ethylene glycol solution, due to its special properties, such as high dielectric loss, high molecular weight, and high boiling point, can serve as a good solvent for microwave heating and is found to be a more suitable medium than the distilled water. A photopyroelectric technique was carried out to measure thermal diffusivity of the samples. The precision and accuracy of this technique was established by comparing the measured thermal diffusivity of the distilled water and ethylene glycol with values reported in the literature. The thermal diffusivity ratio of the silver nanofluids increased up to 1.15 and 1.25 for distilled water and ethylene glycol, respectively.     

Solubility of Acetaminophen in Ethanol + Water + NaCl Mixtures at Various Temperatures

Acetaminophen is a common low water-soluble drug whose solubility could be increased using various methods, including addition of a pharmaceutical cosolvent. The solubility of acetaminophen in ethanol + water + NaCl mixtures at 293.2, 298.2, 303.2, 308.2, and 313.2 K was determined and the results showed that NaCl addition to the solution decreased the solubility. The generated data were mathematically represented using a modified version of the Jouyban–Acree model within an acceptable accuracy.     

Review of Process Industry Accidents Analysis towards Safety System Improvement and Sustainable Process Design

Risk assessment is the tool for maintaining perfect safety management systems and aiding sustainable process design, with hazard identification as the critical step. This step can be executed by past accidents analysis (PAA) to achieve the mentioned objectives. Despite of available analyses, the recurring of accidents identifies the shortcomings in PAA and requires a detailed examination as reported in this review. The intensified exploration of accident information will strengthen both the safety management system at existing facilities and process designing in terms of sustainability.     

3D additive manufacture of oral and maxillofacial surgical models for preoperative planning

This paper investigates the errors generated during the fabrication stage for producing complex anatomical replicas derived from computed tomography coupled with the 3D additive manufacturing methods. Based on this research work, it is shown that patient-specific model based on computed tomography data can be converted into computer numerically controlled G-code. It is shown that 3D extrusion-based additive manufacturing technology is accurate to ±3 % equating to ±200 μm surface deviations due to plastic shrinkage and distortion formed during the process. Polylactic acid plastic extrusion through a 200-μm bore nozzle has resulted in a model being produced with an R_a roughness of 35.5 μm. An evaluation on the errors generated during the fabrication process has been used to accurately produce an adult female mandible. Internal nerve channels and complex external bone geometry has been produced within the model. It is shown that using this process results in bone complexity and accuracy required for producing low-cost surgical grades models which is in comparison with traditional selective laser sintering manufacturing techniques. The surface accuracies suggest that the reproduction of anatomically complex representative structures by 3D plastic extrusion additive manufacturing which can be used for pre-surgical planning.     

Calcium ion-selective electrode based on the facile synthesis of CuO over Cu wires

Here, we report a simple, cost-effective and repeatable process to grow copper(II) oxide (CuO) over a Cu wire. Characterization of the prepared CuO structures revealed a pure phase of CuO with high-density nanostructures. By applying dibenzo-18-crown-6 as an ionophore, CuO (as a solid contact, SC) was developed into a calcium (Ca²⁺) ion-selective electrode (ISE) with a linear activity range between 10 μM and 100 mM, an average Nernstian slope (sensitivity) of 32.3?±?1.3 mV/decade, and a lower limit of detection (LOD) of 10 μM. When tested for selectivity among three ions (magnesium, nickel, and sodium) in addition to the target ion, the electrode had better selectivity toward Ca²⁺ ions. We were able to demonstrate that the proposed Cu/CuO electrode was stable within the pH range from 5.0 to 9.0 for a period of 60 days. Our results of the proposed SC-ISE exhibit a good potential response and acceptable stability, and they show a clear indication that Cu/CuO nanostructures (SC-ISE) can be used as an ion-to-electron transducer for low-cost solid-state potentiometric sensors.

     

Development of a new biosensor for mediatorless voltammetric determination of hydrogen peroxide and its application in milk samples

A new biosensor for the voltammetric detection of hydrogen peroxide was developed based on immobilization of catalase on a clinoptilolite modified carbon paste electrode using bovine serum albumin and glutaraldehyde. The biosensor response was evaluated according to electrode composition, reaction time, solution pH and temperature. The voltammetric signals were linearly in proportion to H₂O₂ concentration in the range 5.0 × 10⁻⁶–1.0 × 10⁻³ M with a correlation coefficient of 0.9975. The detection limit is 8.0 × 10⁻⁷ M and the relative standard deviation for 4.0 × 10⁻⁴ M hydrogen peroxide was 1.83% (n = 6). The biosensor exhibited high sensitivity, and it was determined that it could be used for more than 2 months. In addition, the biosensor was successfully applied for the determination of hydrogen peroxide in milk samples.     

Cavitation during high-temperature deformation in Al–Mg alloys

It has recently been revealed that high-density pre-existing hydrogen micropores, formed during production processes, exhibit premature growth and coalescence under external loading at room temperature, thereby inducing ductile fracture. This process is incidentally supplemented by the well-established ductile fracture mechanism based on particle damage. It is reasonable to assume that the pre-existing hydrogen micropores may also contribute to damage evolution at high temperatures. In the present study, synchrotron X-ray microtomography was applied to the in situ observation of deformation and fracture in Al–Mg alloys at a high temperature. High-density hydrogen micropores were observed in the alloys. Flow localization controlled deformation through the mechanism of solute drag creep. A combined effect of grain boundary sliding and heterogeneous nucleation on particles was also confirmed to accelerate the growth of pre-existing hydrogen micropores and cavities. Although continuous nucleation occurred together with the growth of pre-existing hydrogen micropores, the effects of the pre-existing hydrogen micropores, especially those located on grain boundaries, were predominant in the overall damage evolution. It seemed likely that supersaturated hydrogen in the aluminum alloys might also make an appreciable contribution to cavitation during high-temperature loading.     

Structure and Principal Components Analyses Reveal an Intervarietal Fusion in Malaysian Mistletoe Fig (Ficus deltoidea Jack) Populations

Genetic structure and biodiversity of the medicinal plant Ficus deltoidea have rarely been scrutinized. To fill these lacunae, five varieties, consisting of 30 F. deltoidea accessions were collected across the country and studied on the basis of molecular and morphological data. Molecular analysis of the accessions was performed using nine Inter Simple Sequence Repeat (ISSR) markers, seven of which were detected as polymorphic markers. ISSR-based clustering generated four clusters supporting the geographical distribution of the accessions to some extent. The Jaccard’s similarity coefficient implied the existence of low diversity (0.50–0.75) in the studied population. STRUCTURE analysis showed a low differentiation among the sampling sites, while a moderate varietal differentiation was unveiled with two main populations of F. deltoidea. Our observations confirmed the occurrence of gene flow among the accessions; however, the highest degree of this genetic interference was related to the three accessions of FDDJ10, FDTT16 and FDKT25. These three accessions may be the genetic intervarietal fusion points of the plant’s population. Principal Components Analysis (PCA) relying on quantitative morphological characteristics resulted in two principal components with Eigenvalue >1 which made up 89.96% of the total variation. The cluster analysis performed by the eight quantitative characteristics led to grouping the accessions into four clusters with a Euclidean distance ranged between 0.06 and 1.10. Similarly, a four-cluster dendrogram was generated using qualitative traits. The qualitative characteristics were found to be more discriminating in the cluster and PCA analyses, while ISSRs were more informative on the evolution and genetic structure of the population.