Current Materials Science - Volume 15, Issue 1, 2022

Background: Miniaturized piezoresistive sensors, particularly strain gauges, pressure sensors, and accelerometers, have been used for measurements and control applications in various fields, such as automotive, aerospace, industrial, biomedical, sports, and many more. A variety of different materials have been investigated for the development of these sensors. Among them, diamond- like carbon (DLC) thin films have emerged as one of the most promising piezoresistive sensing materials due to their excellent mechanical properties, such as hardness and high Young’s modulus. At the same time, metal doping has been studied to enhance their electrical properties. Objective: This article explores the use of co-sputtered tungsten-doped diamond-like carbon (WDLC) thin films as microfabricated strain gauges or piezoresistors. Methods: Different serpentine thin-film resistors were microfabricated on co-sputtered W-DLC thin films using photolithography, metallization, lift-off and RIE (reactive ion etching) processes. In order to evaluate their piezoresistive sensing performance, Gauge Factor (GF) measurements were carried out at room temperature using the cantilever beam method. Results: GF values obtained in this study for co-sputtered W-DLC thin films are comparable to those reported for W-DLC films produced and characterized by other techniques, which indicates the feasibility of our approach to using them as sensing materials in piezoresistive sensors. Conclusions: W-DLC thin films produced by the co-magnetron sputtering technique can be considered as sensing materials for miniaturized piezoresistive sensors due to the following key advantages: (i) easy and well-controlled synthesis method, (ii) good piezoresistive properties exhibiting a GF higher than metals, and (iii) thin-film resistors formed by a simple microfabrication process.

Aim: The article aims to describe the rheological behavior of potato starch with reference to different parameters. Methods: Various search engines, such as Science Direct, Google Scholar, Scopus, Google Patents, etc. were used for literature survey. Discussion: The manuscript describes the rheology and its classification. It describes the importance of rheology and factor affecting viscosity. The manuscript focuses on the physicochemical properties of potato starch, rheological properties of potato starch and pharmaceutical uses of potato starch. The rheological property of potato starch depends on the shear rate and viscosity. Conclusion: Rheological behavior of potato starch plays a significant role in food processing. In the future, potato starch will be used in various pharmaceutical companies, manufacturing, daily life and food products.

Nanomaterials are widely used in all walks of life, bring great changes to our life and production. In addition, nanomaterials have also been used in agriculture. The most common ones are carbon-based nanomaterials and TiO2 nanoparticles, which can stimulate plant growth and increase crop yield. However, not all nanomaterials have a positive effect on plant growth. Therefore, it is necessary to understand the influence of nanomaterials on plants after entering the environment. Nanomaterials can be inhaled directly or through endocytosis. Some nanomaterials will become the corresponding ion state to enter the plant, while some larger nanomaterials will block cell wall channels or adsorb on the surface of plants. Nanoparticles (NPs) enter the plant can produce positive or negative effects on the plant's genes, proteins. This paper discusses the effects of nanomaterials on plant growth and on the molecular level.

Background: Crystal Violet Dye (CV) can cause severe eye irritation and cancer due to its adsorption, ingestion, and inhalation effect. Therefore, CV in wastewater systems poses as a severe risk to human health and the environment. It is essential to remove CV before CV is discharged in the environment. Methods: Vanadium doped calcium bismuthate nanoflakes with the vanadium mass ratio of 1 wt%, 3 wt.%, 5 wt.%, and 10 wt.% have been synthesized by a simple hydrothermal route using sodium vanadate as a vanadium raw material. The obtained vanadium doped calcium bismuthate products were analyzed by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and solid diffuse reflection spectrum. Results: XRD patterns show that the vanadium in the doped nanoflakes exists as triclinic Bi3.5V1.2O8.25 and monoclinic Ca0.17V2O5 phases. SEM observations show that the morphology of the products is closely related to the vanadium mass ratio. The morphology changes from the nanoflakes to irregular nanoparticles is observed by increasing the vanadium mass ratio. The bandgap of the nanoflakes decreases to 1.46 eV and 1.01 eV when the doped vanadium mass ratio reaches 5 wt.% and 10 wt.%, respectively. The photocatalytic performance for the CV removal can be greatly enhanced using 5 wt.% and 10 wt.% vanadium doped calcium bismuthate nanoflakes, respectively. By increasing the irradiation time, vanadium mass ratio, and dosage of the nanoflakes, the photocatalytic activity for the CV removal can be improved. Conclusion: 10 wt.% vanadium doped calcium bismuthate nanoflakes have the best photocatalytic performance for CV removal. Vanadium-doped calcium bismuthate nanoflakes exhibit great application potential for the removal of organic pollutants.

Introduction: Plants have been used for thousands of years to treat health disorders, to prevent diseases including epidemics, to flavor and conserve food. It is estimated that 250 to 500 thousand plant species are present on the earth, out of which merely 10 percent are used as a source of food by humans and animals. Objective: In the present work, antibacterial activity of five different Indian spices namely turmeric, clove, pepper, cinnamon and garlic was investigated against pathogens isolated from wound samples Methods: The unknown bacteria were identified by different types of morphological and biochemical techniques such as serial dilutions spread plate methods, morphological studies and biochemical tests. The swabs of the patients were inoculated in 10 mL of sterile nutrient broth and incubated at 37oC for 24 h. The antibacterial activities of these Indian spices were evaluated using the disk diffusion method. A suspension of the microorganisms to be tested was spread on nutrient agar and MacConkey agar medium. The filter paper discs were placed on the agar plates, which were saturated with extract of spice. The plates were then incubated at 37oC for 24 h. The zone of inhibition was determined post-incubation by evaluating the diameter of the zone of inhibition. Results: The antibacterial activities of these Indian spices were evaluated using the disk diffusion method, and the inhibitory zones were recorded. It was quite evident from the result that cinnamon had a larger inhibition zone against P1NA3, P1MAC1 and least for P2NA2. Garlic exhibited a greater zone of inhibition against P2NA2, P3NA3 and least for P1MAC1. Clove had a maximum zone of inhibition against P1MAC2 and least with P3NA3. These spices displayed a zone of inhibition somewhat close to the control antibiotic drug, ampicillin. Conclusion: P1MNC2 showed a maximum zone of inhibition with clove (3 cm) at 100%. P2NA2 showed maximum antibacterial activity with garlic (3.6 cm) at 100% and minimum with cinnamon (1.1cm) at 20%. P3NA3 presented maximum antibacterial activity result with garlic (4.2 cm) at 100% and minimum with clove (1.2cm) at 20%. Spices are economical, more accessible to most of the population in the world. So, medicinal plants should be encouraged as potential candidates for new drugs.

Background: Red Mud (RM) is a solid waste produced by alumina production in the Bayer process. At present, it is being stored or dumped on the land or in the oceans. To utilize RM, extensive work has been done by the researchers to develop various techniques. The production of PC (Polymer Concrete) is one of the economical and efficient methods to recycle the RM. Methods: In this study, the RM has been utilized to fabricate the PC using the recycled PET resin as the binder with fly ash, silica fume and foundry sand as the fillers. By varying the RM content, the influence on the workability, shrinkage, ultrasonic velocity, toughness, modulus of elasticity, mechanical strength, water absorption and acid resistance has been observed. Results: For the specimens cured for 56 days, the values of compressive strength, flexural strength and split tensile strength have been increased by 20.26%, 49.11% and 61.99%, respectively. The water absorption has been reduced by 23.5%. Also, the loss in compressive strength under the effect of the 30%HCl has been decreased by 25%. Conclusion: The specimens containing 20% of red mud content have shown maximum values. Fine particles of RM have increased the mortar compactness and produced high-density PC with reduced density, and the ultrasonic pulse velocity has been reduced due to a decrement in density and modulus of elasticity values.

Background: Nowadays, natural polysaccharides are preferred over synthetic polymers because they are biocompatible, cheap, and easily available than synthetic ones. The polysaccharide obtained from the tuber of the Colocasia esculenta was reported to exhibit many pharmaceutical applications as an excipient. Objective: The application of any polymer in formulating various dosage forms depends upon its qualitative and quantitative chemical composition. Therefore, in the current research work, the quantitative composition of the polysaccharide isolated from Colocasia esculenta was determined by the validated HPLC method. Methods: RP-HPLC analysis was performed on an Agilent, Zorbax Eclipse XDB C8 column (250 mm × 4.6 mm, 5 μm) with the mobile phase consisting of citrate buffer of pH 5.5: Tetrahydrofuran: Acetonitrile (87.1:11.9:1 v/v) at a flow rate of 0.6 mL/min. UV detection was performed at 307 nm. The method was validated for various parameters as per ICH guidelines. Results: The calibration curve constructed for glucose and galactose was found linear with correlation coefficients of 0.997 and 0.994, respectively. The system suitability parameters, such as theoretical plate, tailing factor, and relative standard deviation (RSD), were well within the limits. Solution stability data indicated that the solution was stable for 24 hours at 25°C. The watersoluble polysaccharide from Colocasia esculenta was found to contain glucose and galactose in the ratio 8:1. Conclusion: The validated RP-HPLC method was found to be specific, linear, precise, and accurate and can be successfully used for simultaneous estimation of glucose and galactose content in the polysaccharides.

Background: Additive manufacturing is the most recognized technology which uses metals, polymer, ceramics, and composites for fabrication with a layer-by-layer deposition strategy. Due to its lower cost, higher accuracy, and less material wastage, this technology is used for engineering and domestic applications. But in many applications, there is a need to alter the properties of the product in a specific direction with the help of some reinforcements. With reinforcements, composite layers can be fabricated using additive manufacturing techniques, which will enhance the directional properties. A novel apparatus is designed to spray the reinforcement material into the printed structures quickly and precisely. This spray nozzle is fully automated, which works according to toolpaths generated by slicing software. The alternate deposition of layers of reinforcement and build materials helped to fabricate customized composite products. Objective: This study aims to design and analyze the working principle of a novel composite manufacturing technique that has been developed to fabricate composite materials using additive manufacturing. The apparatus is numerically controlled by computer according to CAD data, which facilitates the deposition of alternate reinforcement and matrix material layers. The major challenges during the design process and the functioning of each component have been explored. Methods: The design process is initiated after a comprehensive literature review is performed to study previous composite manufacturing processes. The recent patents published by different patent offices of the world are studied in detail, and analysis has been used to design a low-cost composite fabrication apparatus. A liquid dispensing device comprises a storage tank attached with a pump and microprocessor. The microprocessor receives the signal from the computer as per tool paths generated by slicing software which decides the spray of reinforcements on polymer layers. The spraying apparatus moves in coordination with the primary nozzle of the Fused Filament Fabrication process. Results: The hybridization of the Fused Filament Fabrication process with the metal spray process has been successfully performed. The apparatus facilitates the fabrication of low-cost composite materials and the flexibility of complete customization of the composite manufacturing process. Conclusion: The anisotropic behavior of products can be easily controlled and managed during fabrication which can be used for different applications.

Introduction: A new series of organic liquid crystal tetramers containing two symmetrical mesogenic units of 4-(4’-phenoxylimino)methyl)phenol joined by methylene –(CH2)mspacer wherein m varied from 5 to 10 have been synthesized. Methods: The length for each of the mesogenic units was extended further via connection with two chiral entities of (S)-2- methylbutyl-4-(4’-bromobutyloxyphenyl)benzoate situated at both terminal ends. The structures of these tetramers were elucidated using elemental analysis and spectroscopic techniques (FT-IR and 1H-NMR) whilst the texture, and the phase transition temperatures were studied using polarizing optical microscopy (POM) along with differential scanning calorimetry (DSC). Results: All the homologues in this series are enantiotropic mesogens exhibiting oily streak texture or fan-shaped texture characteristic of the chiral nematic phase. The odd-even effect can be observed upon increasing the methylene spacer length. The structure-properties connectivity has demonstrated that the phase transition temperature for tetramers with even-numbered methylene units in the spacer is relatively higher in comparison with the odd-numbered members. Conclusion: The computational study via molecular constraint dynamics performed at the DFTB level of theory has further supported that more energy is required for the even-numbered tetramer than the odd-numbered member to undergo the structural transition from folded to extended geometries.

Background: There is a worldwide interest in metal nanoparticles synthesized by various chemical reactions for use in biomedical applications. These processes exhibit a broad range of toxicity in non-target organisms. To avoid chemical toxicity, green synthesis of metal nanoparticles is proposed as a cost-effective and eco-friendly alternative. Aloe vera (A. vera) leaf extract is a medicinal agent with multiple properties, including antibacterial effects. Its constituents include lignin, pectin and hemicellulose, which can be used in the reduction of silver ions to produce silver nanoparticles (AgNPs). Objective: The study aimed at the use of naturally occurring compounds as a reducing and stabilizing agent for the biosynthesis of nanoparticles and investigation of the insecticidal activity of these compounds against Musca domestica (M. domestica) larvae. Methods: Phytochemical analysis of A. vera gel extract was done and the phytochemical components were identified by Gas Chromatography–Mass Spectrometry (GC-MS) analysis. AgNPs and encapsulated Chitosan Nanoparticles (CsNPs) were prepared by an eco-friendly method using A. vera gel extract as a reducing and stabilizing agent. A. vera-AgNPs and A. vera encapsulated CsNPs were characterized using Ultraviolet-visible spectrophotometer (UV–vis spectrum), Transmission Electron Microscopy (TEM), Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD). Then the insecticidal activity of these compounds was investigated against late second instar larvae of the house fly. Results: The most active ingredients identified by GC-MS analysis were Terpene and Sesquiterpene hydrocarbons. The synthesized AgNPs were spherical with an average size of about 12-75 nm, as revealed by TEM. While encapsulated CsNPs ranged between 34-75 nm and the shape seemed spherical with dark parts confirming the encapsulated plant extract. FTIR and XRD results confirmed the successful encapsulation of the gel extract within the chitosan nanoparticles. Results proved the insecticidal potential of the tested compounds against M. domestica larvae, and the relative potency of encapsulated CsNPs was nearly 148.51 times more potent than A. vera crude extract whereas AgNPs was nearly 40.65 times more potent than A. vera crude extract. Furthermore, a prolongation of larval duration and reduction in the percentage pupation and adult emergence were observed. Conclusion: Overall, green-synthesized silver and chitosan nanoparticles have the potential for application as a biopesticide for house fly population control through the use of a safer and costeffective approach.

Background: Nowadays, natural fibers are used in all industrial fields, particularly in automotive technology and civil engineering. This great emergence is due to their biodegradability, recyclability and have no environmental effect. Objective: In this article, the effect of raffia, alfa and sisal fibers on the damage of biocomposite materials (raffia/PLA (polylactic acid), alfa/PLA and sisal/PLA), subjected to the same mechanical shear stress, has been investigated. Methods: To calculate the damage to the interface, the genetic operator crossing is employed based on the fiber and matrix damage. Results: The results have shown that the raffia / PLA and alfa/PLA biocomposite materials are better mechanical properties compared to sisal / PLA, this observation has been confirmed by different values of interface damage of the biocomposite studied. Conclusion: The numerical results are similar and coincide perfectly with the results of Cox where he demonstrated that the Young's modulus of fibers improves the resistance of the interface. These conclusions are in very good agreement with our numerical data presented by the red cloud, and in good agreement with the work presented by Antoine Le Duigou et al. and Bodros et al. in which they have shown that natural fibers greatly improve the physical characteristics of composite materials.