Investigating Thermal Parameters of PVDF Sensor in the Front Pyroelectric Configuration

A metalized PVDF pyroelectric (PE) sensor was used as an optically opaque sensor and in a thermally thick regime for both sensor and sample, instead of a very thick sensor in the conventional front PE configuration. From the frequency dependence measurements, the normalized amplitude and phase signal were independently analyzed to obtain the thermal effusivity of the sensor. The differential normalized amplitude measured with water as a substrate was analyzed to determine the sensor thermal diffusivity. The PVDF thermal diffusivity and thermal effusivity agree with literature values. Then, from the known thermal parameters of the sensor, the thermal effusivity of a standard liquid sample, glycerol, and other liquids were obtained by the similar procedure.     

Fabrication of an Electrically-Resistive,Varistor-Polymer Composite

This study focuses on the fabrication and electrical characterization of a polymer composite based on nano-sized varistor powder. The polymer composite was fabricated by the melt-blending method. The developed nano-composite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FeSEM), and energy-dispersive X-ray spectroscopy (EDAX). The XRD pattern revealed the crystallinity of the composite. The XRD study also showed the presence of secondary phases due to the substitution of zinc by other cations, such as bismuth and manganese. The TEM picture of the sample revealed the distribution of the spherical, nano-sized, filler particles throughout the matrix, which were in the 10–50 nm range with an average of approximately 11 nm. The presence of a bismuth-rich phase and a ZnO matrix phase in the ZnO-based varistor powder was confirmed by FeSEM images and EDX spectra. From the current-voltage curves, the non-linear coefficient of the varistor polymer composite with 70 wt% of nano filler was 3.57, and its electrical resistivity after the onset point was 861 KΩ. The non-linear coefficient was 1.11 in the sample with 100 wt% polymer content. Thus, it was concluded that the composites established a better electrical non-linearity at higher filler amounts due to the nano-metric structure and closer particle linkages.     

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.

     

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.     

Bacterial sensors based on chitosan matrices

Bacterial cells were entrapped together with chitosan matrix onto the surface of graphite electrode to form microbial biosensors. Two types of bacterial sensors were constructed by using Pseudomonas fluorescens (Pseudomonas putida DSM 6521) and P. putida DSM 50026 cells as the biological components and the measurements were based on the respiratory activity of the cells. Carbon nanotube (CNT)-modified chitosan membrane was also prepared to test nanoparticle effect on the efficiency of biosensor performances. As well as the response characteristics, stabilities and substrate specificities were investigated. Data were given as the comparison of CNT-modified and -unmodified systems.     

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.     

Extraction of dibenzothiophene from dodecane using ionic liquids

The effect of ionic liquid loading, extraction temperature, and extraction time in the removal of dibenzothiophene from dodecane were investigated. Eighteen (18) ionic liquids were screened for its dibenzothiophene extraction ability. Imidazolium based ionic liquids with thiocyanate, dicyanamide and octylsulfate anions exhibited the highest extraction capabilities with 66.1%, 66.1%, and 63.6% of extraction efficiency respectively. Tributylmethylammonium methylcarbonate ionic liquid gave 61.9% extraction efficiency, which showed that π-π interaction between aromatic rings of sulfur compound and ionic liquid (IL) was not be the main extraction mechanism. A trend between specific volume and desulfurization efficiency of ILs was put forward, enabling researchers to predict ILs' desulfurization efficiency from its specific volume. It was also found that [C₄mim][SCN] can be reused in extraction without regeneration with considerable extraction efficiency of 41.9%. Huge saving on energy can be achieved if we make use of this IL behavior in process design, instead of regenerating IL after every time of extraction.     

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.     

Green Formation of Spherical and Dendritic Silver Nanostructures under Microwave Irradiation without Reducing Agent

The rapid and green formation of spherical and dendritic silver nanostructures based on microwave irradiation time was investigated. Silver nanoparticles were successfully fabricated by reduction of Ag(+) in a water medium and using polyvinylpyrrolidone (PVP) as the stabilizing agent and without the use of any other reducing agent, and were compared with those synthesized by conventional heating method. UV-vis absorption spectrometry, transmission electron microscopy (TEM), atomic absorption spectroscopy (AAS) and photon correlation spectroscopy (PCS) measurements, indicated that increasing the irradiation time enhanced the concentration of silver nanoparticles and slightly increased the particle size. There was a lack of large silver nanoparticles at a high concentration, but interestingly, the formation and growth of silver dendrite nanostructures appeared. Compared to conventional heating methods, the silver nanoparticle suspension produced by irradiated microwaves was more stable over a six-month period in aqueous solution without any signs of precipitation.