Synergy of silica sand and waste plastics as thermoplastic composites on abrasive wear characteristics under conditions of different loads and sliding speeds.

The diverse nature of polymers with attractive properties has replaced the conventional materials with polymeric composites. The present study was sought to evaluate the wear performance of thermoplastic-based composites under the conditions of different loads and sliding speeds. In the present study, nine different composites were developed by using low-density polyethylene (LDPE), high-density polyethylene (HDPE) and polyethylene terephthalate (PET) with partial sand replacements i.e., 0, 30, 40, and 50 wt%. The abrasive wear was evaluated as per the ASTM G65 standard test for abrasive wear through a dry-sand rubber wheel apparatus under the applied loads of 34.335, 56.898, 68.719, 79.461 and 90.742 (N) and sliding speeds of 0.5388, 0.7184, 0.8980, 1.0776 and 1.4369 (m/s). The optimum density and compressive strength were obtained to be 2.0555 g/cm3 and 46.20 N/mm2, respectively for the composites HDPE60 and HDPE50 respectively. The minimum value of abrasive wear were found to 0.02498, 0.03430, 0.03095, 0.09020 and 0.03267 (cm3) under the considered loads of 34.335, 56.898, 68.719, 79.461 and 90.742 (N), respectively. Moreover, the composites LDPE50, LDPE100, LDPE100, LDPE50PET20 and LDPE60 showed a minimum abrasive wear of 0.03267, 0.05949, 0.05949, 0.03095 and 0.10292 at the sliding speeds of 0.5388, 0.7184, 0.8980, 1.0776 and 1.4369 (m/s), respectively. The wear response varied non-linearly with the conditions of loads and sliding speeds. Micro-cutting, plastic deformations, fiber peelings, etc. were included as the possible wear mechanism. The possible correlations between wear and mechanical properties, and throughout discussions for wear behaviors through the morphological analyses of the worn-out surfaces were provided.

Strength Evaluation of Functionalized MWCNT-Reinforced Polymer Nanocomposites Synthesized Using a 3D Mixing Approach.

The incorporation of carboxyl functionalized multi-walled carbon nanotube (MWCNT- COOH) into a polymethyl methacrylate (PMMA) has been investigated. The resultant tensile and flexural mechanical properties have been determined. In this paper, a novel synthesis process for a MWCNT-reinforced polymer nanocomposite is proposed. The proposed method significantly eliminates the most challenging issues of the nano-dispersed phase, including agglomeration and non-homogeneous mixing within a given matrix material, and also resolves the issues occurring in conventional mixing processes. The results of scanning electron microscopy support these claims. This 3D-mixing process is followed by an extrusion process, using a twin-screw extruder for pristine MWCNT, and a compression molding process for COOH-MWCNT, to prepare test specimens for experimentally determining the mechanical properties. The test specimens are fabricated using 0.1, 0.5, and 1.0 wt.% MWCNT, with a remaining PMMA phase. The testing is conducted according to ASTM D3039 and ASTM D7264 standards. Significant improvements of 25.41%, 35.85%, and 31.75% in tensile properties and 18.27%, 48%, and 33.33% in flexural properties for 0.1, 0.5, and 1.0 wt.% COOH-MWCNT in PMMA, respectively, compared to non-functionalized MWCNTs, were demonstrated. The highest strength was recorded for the nanocomposite with 0.5 wt.% f-MWCNT content, indicating the best doping effect at a lower concentration of f-MWCNT. The proposed CNT-PMMA nanocomposite may be found suitable for use as a scaffold material in the domain of bone tissue engineering research. This type of research possesses a high strength requirement, which may be fulfilled using MWCNT. Furthermore, this analysis also shows a significant amount of enhancement in flexural strength, which is clinically required for fabricating denture bases.

Titanium Allergy in Dentistry: A New Allergen in Rapidly Evolving Implant Dentistry.

Although titanium is considered as the biocompatible material and widely used in medical and dental fields, the clinical application of this material is still a critical issue due to the possible adverse host response. Very few case reports related with titanium-based hypersensitivity reactions with dental implants proved the existence of titanium allergy. The present case report describes 56-year-old male showing allergic symptoms after 1 week of dental implant placement with no perioral or facial signs, but eczema was shown on the distant body parts, and the complete remission was attained after removing the dental implant.

Vibration Exposure and Transmissibility on Dentist's Anatomy: A Study of Micro Motors and Air-Turbines.

The use of dental hand pieces endanger dentists to vibration exposure as they are subjected to very high amplitude and vibration frequency. This paper has envisaged a comparative analysis of vibration amplitudes and transmissibility during idling and drilling with micro motor (MM) and air-turbine (AT) hand pieces. The study aims to identify the mean difference in vibration amplitudes during idling, explore different grasp forces while drilling with irrigant injection by the dentist, and various vibration transmission of these hand pieces. The study utilized 22 separate frequency resonances on two new and eight used MMs and two new and eight used ATs of different brands by observing the investigator at 16 different dentist clinics. The study adopted a descriptive research design with non-probability sampling techniques for selecting dentists and hand pieces. Statistical methods like Levene Test of Homogeneity, Welch ANOVA, independent t-test, and Games-Howell test were utilized with SPSS version 22 and MS-Excel. The results reveal that vibration amplitudes and vibration transmissibility when measured at position 2 are higher than in another position 1. Vibrations during idling for used MMs are more than AT hand pieces, and the used MM (MUD) and used AT (AUA) hand pieces differ due to their obsolescence and over-usage. Vibration amplitudes increase every time with the tightening of grasping of the hand piece. Vibration amplitudes for each grasping style of MM hand piece differ from all other grasping styles of AT hand pieces. Routine exposure to consistent vibrations has ill physical, mental, and psychological effects on dentists. The used hand pieces more hazardous as compared to newer ones. The study suggests that these hand pieces must be replaced periodically, sufficient to break between two operations, especially after every hand piece usage. Hence, the present research work can be further extended by creating some control groups among dentists and then studying the vibration amplitude exposure of various dental hand pieces and subsequent transmissibility to their body parts.

On the characterization of functionally graded biomaterial primed through a novel plaster mold casting process.

The current work presents a novel plaster mold casting (PMC) process for fabricating functionally graded biodegradable materials (FGBMs) for orthopedics applications. According to the proposed route, the plaster molds were first prepared by using a hybrid and variable mixture of Plaster of Paris (PoP) and hydroxyapatite (HAP). Upon drying, molten magnesium (Mg) alloy was poured in the mold cavity and allowed to solidify. Various experiments have been conducted as per Taguchi based design of experimentation to study the effect of PoPX/HAP proportion, mixing time, and baking times on mechanical, corrosion, and cytocompatibility performances of the resulting FGBM. It has been revealed by the scanning electron microscopy (SEM) that uniform layers of HAP particles were developed on the prepared specimens, revealed the novelty of the route. The mechanical properties, in case of surface hardness and impact strength, the optimum results were obtained with PoP(x = 90% by wt.) and HAP(y = 10% by wt.). Further, the corrosion investigations highlighted that the sample prepared with PoP(x = 70% by wt.) and HAP(y = 30% by wt.) proportion possessed excellent corrosion resistance. Moreover, the cytocompatibility analysis revealed that all the developed FGBM are substantially bioactive and promoted cell adhesion, proliferation, differentiation, and various other cytoplasmic activities. However, in this case, FGBM with PoP(x = 70% by wt.) and HAP(y = 30% by wt.) proportion was found superior. The overall results of the present work supported the developed FGBM components and involved the PMC route as a potential candidate for various orthopedics fabrications.

3D printed biodegradable functional temperature-stimuli shape memory polymer for customized scaffoldings.

Shape memory polymers (SMPs) and their composites have become the prominent choice of the various industries owing to the unique inherent characteristics which can be stimulated through the exposure of external stimuli. The use of SMPs in the three-dimensional (3D) technologies has produced enormous advantages. However, the potential of SMPs in 3D printing has limitedly explored. In the present study, an investigation was performed to study the shape memory effect (SME) of the fused filament fabricated (FFF) chitosan (CS) reinforced poly-lactic-acid (PLA) based porous scaffolds. Firstly, the composite filaments, with 1, 1.5, and 2% wt. of CS, were fabricated by using the twin-screw extrusion process, which was later used to print the test specimens at different infill density. The printed samples were selectively pre-elongated to 2.5 mm and then processed through direct heating, at 60-70 °C, for enabling the SME. It has been observed that the CS particles acted as rigid phases and interrupted the re-ordering of PLA chain. However, the scaffoldings showed 18.8% shape recovery at optimized process parametric settings. In addition, wettability and biocompatibility analyses of developed scaffoldings have also been performed to investigate the biological aspects of the developed scaffoldings. The stimulated samples found to be possessed with good wettability and cell proliferation. Overall, the 3D printed PLA/CS porous scaffoldings have shown significant shape recovery characteristics and are biologically active to be used as self-healing implants for acute bone deficiencies.

Trigeminal neuralgia secondary to cerebellopontine angle tumor: A case report and brief overview.

Trigeminal neuralgia (TN) is a paroxysmal shock-like pain restricted to innervations of the areas of one or more branches of the trigeminal nerve, often set off by light stimuli in a trigger zone. Pain attacks occur spontaneously and can also be triggered by a nonpainful sensory stimulus to the skin, intraoral mucosa surrounding the teeth, or tongue. The pathogenesis of TN is uncertain and typically is idiopathic, but it may be due to a structural lesion. Some pathologies include traumatic compression of the trigeminal nerve by neoplastic or vascular anomalies and intracranial tumors or demyelinating conditions such as multiple sclerosis. This case report describes an epidermoid cyst at the cerebellopontine angle in a 25-year-old young man with otherwise classical unilateral TN. The case highlights the difficulties of diagnosis and the importance of a multidisciplinary approach in making the correct diagnosis in symptomatic as well as classical TN.