scholarly journals Tribological and Thermal Transport Performance of SiO2-Based Natural Lubricants

Lubricants ◽  
2019 ◽  
Vol 7 (8) ◽  
pp. 71 ◽  
Author(s):  
Jaime Taha-Tijerina ◽  
Karla Aviña ◽  
Jose Manuel Diabb
Keyword(s):  
High Performance ◽  
Skin Diseases ◽  
Sio2 Nanoparticles ◽  
Maximum Enhancement ◽  
Mineral Oils ◽  
Load Carrying ◽  
Sunflower Oils ◽  
The Coefficient Of Friction ◽  
Filler Fraction ◽  
Friction Performance

Fluids and lubricants are critical for the mechanical manufacturing processing of metals, due to a high amount of friction generated, also reflected as heat, could wear and damage tooling and machine components. The proper application of lubricants increases machinery lifetime, decreases long-term costs, and energy and time consumption due to the maintenance or components exchange/repairs. Besides being non-renewable, mineral oils bring consequences to the environment due to their low biodegradability and could affect the user with respiratory and skin diseases. Recently, due to an increase in environmental awareness, the search of biocompatible and efficient lubricants has become a technology goal. The vegetable oil-based lubricants are slowly emerging as ecofriendly and high-performance alternatives to petroleum-based lubricants. This study evaluates soybean, sunflower, corn and paraffinic oils reinforced with SiO2 nanoparticles. The thermal and tribological evaluations were performed varying the temperature and nanofiller concentrations. The thermal conductivity improvements were observed for all nanolubricants as the temperature and filler fraction increased. The highest thermal conductivities were observed at 323 K with 0.25 wt % SiO2. The soybean and corn oils unveiled a maximum enhancement of ~11%. The tribological evaluations showed that SiO2 addition, even in small concentration, resulted into a significant improvement on a load-carrying capacity. For instance, at 0.25 wt % enhancements of 45% and 60% were observed for soybean and sunflower oils, respectively. The coefficient of friction performance also showed enhancements between 10% and 26%.

scholarly journals Multi-level characteristics of TiOx transparent non-volatile resistive switching device by embedding SiO2 nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sera Kwon ◽  
Min-Jung Kim ◽  
Kwun-Bum Chung
Keyword(s):  
Resistive Switching ◽  
High Performance ◽  
Sio2 Nanoparticles ◽  
Visible Range ◽  
Resistive State ◽  
Switching Device ◽  
Structural Density ◽  
Multi Level ◽  
Switching Characteristics ◽  
Switching Devices

AbstractTiOx-based resistive switching devices have recently attracted attention as a promising candidate for next-generation non-volatile memory devices. A number of studies have attempted to increase the structural density of resistive switching devices. The fabrication of a multi-level switching device is a feasible method for increasing the density of the memory cell. Herein, we attempt to obtain a non-volatile multi-level switching memory device that is highly transparent by embedding SiO2 nanoparticles (NPs) into the TiOx matrix (TiOx@SiO2 NPs). The fully transparent resistive switching device is fabricated with an ITO/TiOx@SiO2 NPs/ITO structure on glass substrate, and it shows transmittance over 95% in the visible range. The TiOx@SiO2 NPs device shows outstanding switching characteristics, such as a high on/off ratio, long retention time, good endurance, and distinguishable multi-level switching. To understand multi-level switching characteristics by adjusting the set voltages, we analyze the switching mechanism in each resistive state. This method represents a promising approach for high-performance non-volatile multi-level memory applications.

Graphite@Silicon embedded in Carbon Conformally Coated Tiny SiO2 Nanoparticles Matrix for High-Performance Lithium-Ion Batteries

2021 ◽  
Author(s):  
Huitian Liu ◽  
Xu Liu ◽  
Zhaolin Liu ◽  
Junyan Tao ◽  
Xiaoqian Dai ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Large Volume ◽  
Volume Expansion ◽  
Anode Materials ◽  
High Performance ◽  
Lithium Ion ◽  
Sio2 Nanoparticles ◽  
Carbon Composites ◽  
Effective Strategy ◽  
Si Anode

Engineering of graphite@Si/carbon composites is considered as an effective strategy to surmount the shortcomings of low conductivity and large volume expansion of bare Si anode materials for lithium-ion batteries. Nevertheless,...

scholarly journals Determination of Ten Corticosteroids in Illegal Cosmetic Products by a Simple, Rapid, and High-Performance LC-MS/MS Method

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Vita Giaccone ◽  
Giuseppe Polizzotto ◽  
Andrea Macaluso ◽  
Gaetano Cammilleri ◽  
Vincenzo Ferrantelli
Keyword(s):  
High Performance ◽  
Skin Diseases ◽  
Gradient Elution ◽  
Reversed Phase ◽  
Cosmetic Products ◽  
Chromatography Method ◽  
Esi Ms ◽  
Negative Ionization Mode ◽  
Negative Ionization

The aim of our present work was the development of a rapid high-performance liquid chromatography method with electrospray ionization and tandem mass spectrometry detection (LC-ESI-MS/MS) for the determination of several corticosteroids in cosmetic products. Corticosteroids are suspected to be illegally added in cosmetic preparations in order to enhance the curative effect against some skin diseases. Sample preparation step consists in a single extraction with acetonitrile followed by centrifugation and filtration. The compounds were separated by reversed-phase chromatography with water and acetonitrile (both with 0.1% formic acid) gradient elution and detected by ESI-MS positive and negative ionization mode. The method was validated at the validation level of 0.1 mg kg−1. Linearity was studied in the 5–250 μg L−1 range and linear coefficients (r2) were all over 0.99. The accuracy and precision of the method were satisfactory. The LOD ranged from 0.085 to 0.109 mg kg−1 and the LOQ from 0.102 to 0.121 mg kg−1. Mean recoveries for all the analytes were within the range 91.9–99.2%. The developed method is sensitive and useful for detection, quantification, and confirmation of these corticosteroids in cosmetic preparations and can be applied in the analysis of the suspected samples under investigation.

Physical characterisation and stability study of formulated Chromolaena odorata gel

2021 ◽  
Vol 18 ◽  
Author(s):  
Qurratul Ain Zakirah Mohd Zamram ◽  
Hannis Fadzillah Mohsin ◽  
Mashani Mohamad Mohamad ◽  
Nurul Aqmar Mohamad Nor Hazalin ◽  
Khuriah Abdul Hamid
Keyword(s):  
High Performance ◽  
Skin Diseases ◽  
Loss Modulus ◽  
Viscosity Index ◽  
Stability Study ◽  
Wound Management ◽  
Flavonoid Compound ◽  
Chromolaena Odorata ◽  
Skin Delivery ◽  
Materials Used

Aim: Formulating topical products for skin delivery has always been a challenge for pharmaceutical scientists to fulfil good formulation criteria. Despite the challenges, gel-based drug delivery offers some advantages such that it is non-invasive, painless, avoidance of the first-pass metabolism and has satisfactory patient compliance. Objectives: In this study, Chromolaena odorata gel and quercetin gel (bioactive flavonoid compound) were successfully formulated and compared with placebo and conventional wound aid gel. The chromatographic profilling was conducted to screen the presence of phytoconstituents. Subsequently, all formulated gels were subjected to physical characteristic and stability study. Methods: Reverse Phase High-Performance Liquid Chromatography (RP-HPLC) of C.odorata methanolic leaves extract shows a distinct compound separation at retention time 8.4min to 34.8 min at 254nm. All gels were characterised by evaluating their rheological properties including storage modulus, loss modulus and plastic viscosity. Besides, texture analysis was performed to measure the gels’ firmness, consistency, cohesiveness, and viscosity index. Results: From the observation, C. odorata gel demonstrated better spreadability as compared to the other gels, which acquired less work and favourable to be applied onto the skin. Moreover, C. odorata gel showed no changes in organoleptic properties and proven to be stable after 30 days of accelerated stability study at 40°C ± 2°C with relative humidity (RH) of 75%± 5%. Conclusion: C. odorata gel has shown to be stable, reflecting the combination of materials used in the formulation, which did not degrade throughout the study. This work suggests the potential of this gel as a vehicle to deliver the active ingredients of C. odorata to the skin, which can be further explored as a topical application in antimicrobial wound management or other skin diseases study.

scholarly journals Determination of Axial Capacity for Enhanced Normal and Ultra - High Performance Concrete Columns

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sarmad Shafeeq Abdulqader ◽  
Asmaa Ali Ahmed ◽  
Nawfal Shihab Ahmed
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Peak Load ◽  
Concrete Cover ◽  
Ultra High Performance Concrete ◽  
Concrete Technology ◽  
Compression Load ◽  
Axial Capacity ◽  
Load Carrying ◽  
Normal Strength

Abstract Concrete Technology has been developing for more than a century. One of the most exceptional achievements in concrete technology is the evolving of Ultra-High Performance Concrete (UHPC) which has been a research focus in a wide applications diversity. In this paper, an experimental work has been carried out for investigating the transverse and longitudinal reinforcements’ variation influence on the axial capacity of UHPC columns. Eight columns (five UHPC columns and three Normal Strength Concrete (NSC) columns) have been poured and tested under a concentric axial compression load till a failure is reached. Then, the results are reported herein. The experimental results show that UHPC columns failed in a controlled manner and no concrete chips or a concrete cover spalling are observed. Also, the longitudinal reinforcements have not buckled away beyond the peak load because of the presence of the reinforcing steel fibers in UHPC. Correspondingly, the steel ties spacing proportionally affects the load carrying capacity of columns as presented hereinafter.

scholarly journals Calculation of Axial Compression Capacity for Square Columns Strengthened with HPFL and BSP

2016 ◽  
Vol 2016 ◽  
pp. 1-11
Author(s):  
Hua Huang ◽  
Kailin Xi ◽  
Yu Zhang ◽  
Jinghui Shi ◽  
Boquan Liu
Keyword(s):  
Bearing Capacity ◽  
Axial Compression ◽  
High Performance ◽  
Reduction Factor ◽  
Steel Plates ◽  
Strength Reduction Factor ◽  
Compression Performance ◽  
Load Carrying ◽  
Calculation Results ◽  
Primary Damage

The load carrying capacity and failure mechanism of 8 square columns strengthened with high-performance ferrocement laminate (HPFL) and bonded steel plates (BSP) were analyzed on the basis of experiments on the axial compression performance of these columns. Results show that the reinforcing layer worked together with the original columns as a whole, and the load-bearing capacity significantly increased. When failure of the strengthened column occurred, the mortar and concrete were crushed and bulged outward in the middle of the columns, the angle bars and longitudinal steel bars buckled, and some stirrups were pulled out. The chamfering of angle bar momentously affected the primary damage of steel strand. The values of the strength reduction factor and pressure effective utilization coefficient of the mortar were suggested. Based on the experiments and existing tests of 35 columns strengthened with HPFL, equations for the axial compression bearing capacity were proposed and all calculation results agreed well with testing results. Therefore, the calculation method could be used in the capacity design of axial compression strengthened columns.

Density Variation Effects in Stepped-Thrust Bearings

1959 ◽  
Vol 26 (3) ◽  
pp. 337-340
Author(s):  
C. F. Kettleborough
Keyword(s):  
Coefficient Of Friction ◽  
Carrying Capacity ◽  
Thrust Bearing ◽  
Density Variation ◽  
Load Carrying Capacity ◽  
Thrust Bearings ◽  
Load Carrying ◽  
The Coefficient Of Friction

Abstract The problem of the stepped-thrust bearing is considered but, whereas normally volumetric continuity is assumed, the equations are solved assuming mass continuity; i.e., the variation of density is also considered as well as the effect of the stepped discontinuity on the load-carrying capacity and the coefficient of friction. Computed theoretical curves illustrate the importance of the density on the operation of this bearing and, in part, explain results already published.

The effect of V-shape protruded and dimple textured on the load-carrying capacity and coefficient of friction of hydrodynamic journal bearing: A comparative numerical study

2020 ◽  
pp. 135065012093500
Author(s):  
Sanjay Sharma ◽  
Aniket Sharma ◽  
Gourav Jamwal ◽  
Rajeev Kumar Awasthi
Keyword(s):  
Coefficient Of Friction ◽  
Carrying Capacity ◽  
Performance Enhancement ◽  
Numerical Study ◽  
Geometrical Parameters ◽  
Load Carrying Capacity ◽  
Enhancement Ratio ◽  
Load Carrying ◽  
The Coefficient Of Friction ◽  
Computing Performance

The present comparative numerical study is between V-shape protruded, dimple textured, and untextured bearing. The performance parameters in terms of the load-carrying capacity and coefficient of friction are computed by solving governing Reynold’s equation of the lubricant fluid flow. The governing equation is solved by the finite element method by assuming that the fluid is Newtonian and isoviscous in nature. The effect of eccentricity ratios, texture distribution, texture heights, and texture depths are considered for the analysis in both textured bearings. From simulated results, the load-carrying capacity and coefficient of friction is found to be maximum for protruded textured bearing in full textured region and first half-textured region respectively as compared to untextured bearings. Finally, optimal operating and geometrical parameters of textured bearing is obtained by computing performance enhancement ratio, which is the ratio of the load-carrying capacity to the coefficient of friction. The maximum value of the performance enhancement ratio is found for protruded and dimple textured bearing in full texturing and second half-region corresponding to the eccentricity ratio of 0.8 and 0.6 respectively at texture height and depth of 0.4.

scholarly journals Influence of SiO2 Content and Exposure Periods on the Anticorrosion Behavior of Epoxy Nanocomposite Coatings

Coatings ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 118 ◽  
Author(s):  
Alam ◽  
Samad ◽  
Sherif ◽  
Poulose ◽  
Mohammed ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
High Performance ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Sio2 Nanoparticles ◽  
Epoxy Coating ◽  
Properties Of Coatings ◽  
Ft Ir ◽  
Eis Measurements ◽  
Coating Formulations

Epoxy coating formulations containing 1%, 3%, and 5% SiO2 nanoparticles were produced and applied on a mild steel substrate to achieve the objective of high performance corrosion resistance. The electrochemical impedance spectroscopy (EIS) technique was employed to measure the anticorrosive properties of coatings. The corrosion tests were performed by exposing the coated samples in a solution of 3.5% NaCl for different periods of time, varied from 1 h and up to 30 days. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analyses revealed the presence of nanoparticles in the final cured samples. Establishing the incorporation of the nanoparticles in the coating formulations was confirmed by employing both of XRD and FT-IR techniques. The FT-IR spectra have proved to be satisfactory indicating that there was a complete reaction between the epoxy resin with the hardener. EIS measurements confirmed that the presence and the increase of SiO2 nanoparticles greatly improved the corrosion resistance of the epoxy coating. The highest corrosion resistance for the coatings was obtained for the formulation with 5% SiO2 nanoparticles content, particularly with prolonging the immersion time to 30 days.

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