1,247 results match your criteria hardness calculated


Thermochemical Properties and Growth Mechanism of the Ag-Doped Germanium Clusters, AgGe with = 1-13 and λ = -1, 0, and +1.

Authors:
Bin Liu Jucai Yang

ACS Omega 2021 Apr 31;6(14):9813-9827. Epub 2021 Mar 31.

School of Chemical Engineering, Inner Mongolia Key Laboratory of Theoretical and Computational Chemistry Simulation, Inner Mongolia University of Technology, Hohhot 010051, People's Republic of China.

A systematic investigation of the silver-doped germanium clusters AgGe with = 1-13 in the neutral, anionic, and cationic states is performed using the unbiased global search technique combined with a double-density functional scheme. The lowest-energy minima of the clusters are identified based on calculated energies and measured photoelectron spectra (PES). Total atomization energies and thermochemical properties such as electron affinity (EA), ionization potential (IP), binding energy, hardness, and highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap are obtained and compared with those of pure germanium clusters. Read More

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Hydrochemical characterization and quality assessment of groundwater in the hilly area of the Taihang Mountains in Henan Province, China.

Environ Sci Pollut Res Int 2021 Apr 10. Epub 2021 Apr 10.

Henan Institute of Geological Environment Monitoring, Zhengzhou, 450016, China.

This study evaluated the quality of groundwater and its suitability for drinking and irrigation in the hilly area of the Taihang Mountains in Henan Province, China. Groundwater samples were collected from 43 unconfined and 20 confined wells and analyzed. The pollution index of groundwater (PIG) was estimated based on the physicochemical parameters, and seven indices, including the sodium adsorption ratio (SAR), sodium percentage (%Na), residual sodium carbonate (RSC), permeability index (PI), magnesium ratio (MR), Kelley's ratio (KR), and corrosivity ratio (CR), were calculated to qualify the groundwater within the research area for irrigation activities. Read More

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QSPR modelling for intrinsic viscosity in polymer-solvent combinations based on density functional theory.

SAR QSAR Environ Res 2021 Apr 7:1-15. Epub 2021 Apr 7.

Department of Chemical Engineering, Sichuan University, Chengdu, PR China.

Linear and nonlinear quantitative structure-property relationship (QSPR) models were developed based on a dataset with 65 polymer-solvent combinations. Seven quantum chemical descriptors, dipole moment, hardness, chemical potential, electrophilicity index, total energy, HOMO and LUMO orbital energies, were calculated with density functional theory at the B3LYP/6-31 G(d) level for polymers and solvents. Considering the strong correlation between intrinsic viscosity and weight, size, shape as well as topological structure of polymers and solvents, topological descriptors were also applied in this work. Read More

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Growth, spectral, optical, electrical and computational analysis of sodium oxalate single crystals.

Heliyon 2021 Mar 21;7(3):e06527. Epub 2021 Mar 21.

Department of Chemistry, St Berchmans College (Autonomous), Changanassery, 686101, Kerala, India.

Single crystals of Sodium Oxalate (SO) were grown by adopting the slow evaporation solution growth approach from aqueous solution. The prominent functional groups seen in the SO crystal were distinctly detected with Fourier transform infrared and FT-Raman spectral analysis. The cut-off wavelength of 230 nm was measured using Ultraviolet -visible spectral analysis. Read More

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Staling of white wheat bread crumb and effect of maltogenic α-amylases. Part 3: Spatial evolution of bread staling with time by near infrared hyperspectral imaging.

Food Chem 2021 Mar 6;353:129478. Epub 2021 Mar 6.

Chemometrics Analytical Technology, Department of Food Science, Faculty of Science, University of Copenhagen, Rolighedsvej 30, 1958 Frederiksberg C, Denmark.

This paper explores how the staling of white bread affects the behavior of the whole crumb surface and how that mechanism is interrupted/changed by the addition of maltogenic α-amylases. This is done using near infrared hyperspectral imaging, machine learning methodologies and the knowledge acquired in the previous two manuscripts. Methods like principal component analysis and multivariate curve resolution demonstrate how the constituents of the bread being stored (for 21 days) evolve differently depending on the presence/absence of maltogenic α-amylases and also which parts of the crumb are primarily exposed to changes. Read More

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Influence of radiant exposure values from two third generation LED curing units on polymerization profile and microhardness of orthodontic composite under ceramic and metallic brackets.

Dental Press J Orthod 2021 10;26(1):e2119150. Epub 2021 Mar 10.

Universidade Estadual de Ponta Grossa, Departamento de Odontologia (Ponta Grossa/PR, Brazil).

Introduction: Third generation of LED light curing units might be used in short exposure periods for orthodontic brackets bonding.

Objective: This study evaluated the effect of the different radiant exposure (RE) values: Manufacturers' instructions (MI), ½ MI, 1/4 MI and Turbo mode. Two third-generation LED curing units were used: VALO® and Bluephase 20i® . Read More

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An ab-initio study on structural, elastic, electronic, bonding, thermal, and optical properties of topological Weyl semimetal TaX (X = P, As).

Authors:
M I Naher S H Naqib

Sci Rep 2021 Mar 10;11(1):5592. Epub 2021 Mar 10.

Department of Physics, University of Rajshahi, Rajshahi, 6205, Bangladesh.

In recent days, study of topological Weyl semimetals have become an active branch of physics and materials science because they led to realization of the Weyl fermions and exhibited protected Fermi arc surface states. Therefore, topological Weyl semimetals TaX (X = P, As) are important electronic systems to investigate both from the point of view of fundamental physics and potential applications. In this work, we have studied the structural, elastic, mechanical, electronic, bonding, acoustic, thermal and optical properties of TaX (X = P, As) in detail via first-principles method using the density functional theory. Read More

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Computational property predictions of Ta-Nb-Hf-Zr high-entropy alloys.

Sci Rep 2021 Mar 1;11(1):4815. Epub 2021 Mar 1.

TCS Research, Tata Research Development and Design Center, 54-B Hadapsar Industrial Estate, Hadapsar, Pune, Maharashtra, 411013, India.

Refractory high entropy alloys (R-HEAs) are becoming prominent in recent years because of their properties and uses as high strength and high hardness materials for ambient and high temperature, aerospace and nuclear radiation tolerance applications, orthopedic applications etc. The mechanical properties like yield strength and ductility of TaNbHfZr R-HEA depend on the local nanostructure and chemical ordering, which in term depend on the annealing treatment. In this study we have computationally obtained various properties of the equimolar TaNbHfZr alloy like the role of configurational entropy in the thermodynamic property, rate of evolution of nanostructure morphology in thermally annealed systems, dislocation simulation based quantitative prediction of yield strength, nature of dislocation movement through short range clustering (SRC) and qualitative prediction of ductile to brittle transition behavior. Read More

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Model for liver hardness using two-dimensional shear wave elastography, durometer, and preoperative biomarkers.

World J Gastrointest Surg 2021 Feb;13(2):127-140

Department of Hepatobiliary and Pancreatic Surgery, The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310009, Zhejiang Province, China.

Background: Post-hepatectomy liver failure (PHLF) increases morbidity and mortality after liver resection for patients with advanced liver fibrosis and cirrhosis. Preoperative liver stiffness using two-dimensional shear wave elastography (2D-SWE) is widely used to evaluate the degree of fibrosis. However, the 2D-SWE results were not accurate. Read More

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February 2021

Effect of fluoride varnish on glass ionomer microhardness changes in endogenous acid erosion challenge.

Biomater Investig Dent 2021 Feb 10;8(1):18-23. Epub 2021 Feb 10.

Department of Operative Dentistry, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.

Objective: This study aimed to assess the effect of fluoride varnish on glass ionomer microhardness changes after endogenous acid erosion challenge.

Methodology: In this study, 40 conventional glass ionomer (CGI; Fuji IX) and 40 resin-modified glass ionomer (RMGI; Fuji IILC) discs were fabricated and divided into 4 subgroups ( = 10) for immersion in synthetic gastric acid or saliva for 27 h with/without fluoride varnish application. The surface microhardness was measured at baseline and after immersion, and the change in microhardness was calculated. Read More

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February 2021

Determination of Hardness and Fracture Toughness of Y-TZP Manufactured by Digital Light Processing through the Indentation Technique.

Biomed Res Int 2021 12;2021:6612840. Epub 2021 Feb 12.

State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China.

Objective: The purpose of the study was to determine the hardness and fracture toughness of dental yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) manufactured by digital light processing (DLP) technology to study its clinical prospects.

Methods: The experimental group was DLP-manufactured zirconia, and the control group was milled zirconia. The hardness was investigated under a range of test loads (0. Read More

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February 2021

Design of a Series of Metallic BN with Tunable Mechanical Properties.

J Phys Chem Lett 2021 Feb 17;12(7):1979-1984. Epub 2021 Feb 17.

Center for High Pressure Science (CHiPS), State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, China.

Here a series of sp-sp BN ( = 1, 2, 3, 4, 5, 6) structures was constructed. These structures can be viewed as diamond-like BN blocks connected by single N-N bonds. Elastic constants and phonon dispersion curves confirm that all of the proposed structures are mechanically and dynamically stable. Read More

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February 2021

Temporal and spatial variations of surface water quality in the Nile River of Damietta Region, Egypt.

Environ Monit Assess 2021 Feb 15;193(3):128. Epub 2021 Feb 15.

Zoology Department, Faculty of Science, Damietta University, Damietta, Egypt.

Temporal/spatial variations of surface water quality were examined for the Nile River in the Damietta region where it serves as the major source of water for the inhabitants of Damietta Governorate. A total of 32 water quality parameters were monitored at six sampling sites for 12 months from February 2016 to January 2017. Higher values of chemical oxygen demand (COD), biological oxygen demand (BOD), heavy metals, and nutrients were observed upstream. Read More

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February 2021

IrN and IrN as potential high-energy-density materials.

J Chem Phys 2021 Feb;154(5):054706

State Key Laboratory of Metastable Materials Science & Technology and Key Laboratory for Microstructural Material Physics of Hebei Province, School of Science, Yanshan University, Qinhuangdao 066004, China.

Transition metal nitrides have attracted great interest due to their unique crystal structures and applications. Here, we predict two N-rich iridium nitrides (IrN and IrN) under moderate pressure through first-principles swarm-intelligence structural searches. The two new compounds are composed of stable IrN octahedrons and interlinked with high energy polynitrogens (planar N or cyclo-N). Read More

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February 2021

Quantum computational investigations and molecular docking studies on amentoflavone.

Heliyon 2021 Jan 30;7(1):e06079. Epub 2021 Jan 30.

Departamento de Análises Clínicas e Toxicológicas, Centro de Ciências da Saúde, Universidade Federal do Ceará, Campus Porangabussu, 60430-370, Fortaleza, Ceará, Brazil.

Chagas disease is a neglected tropical disease caused by the protozoan parasite , with approximately 6-7 million people infected worldwide, becoming a public health problem in tropical countries, thus generating an increasing demand for the development of more effective drugs, due to the low efficiency of the existing drugs. Aiming at the development of a new antichagasic pharmacological tool, the density functional theory was used to calculate the reactivity descriptors of amentoflavone, a biflavonoid with proven anti-trypanosomal activity in vitro, as well as to perform a study of interactions with the enzyme cruzain, an enzyme key in the evolutionary process of . Structural properties (in solvents with different values of dielectric constant), the infrared spectrum, the frontier orbitals, Fukui analysis, thermodynamic properties were the parameters calculated from DFT method with the monomeric structure of the apigenin used for comparison. Read More

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January 2021

Electron deficiency but semiconductive diamond-like BCN originated from three-center bonds.

Phys Chem Chem Phys 2021 Feb;23(4):3087-3092

Department of Materials Science, State Key Lab of Superhard Materials, Jilin University, Changchun 130012, China.

B2CN was one of the synthesized light element compounds, which was expected to be superhard material with a metallic character due to its electron deficienct nature. However, in this work, we discovered two novel semiconducting superhard B2CN phases using particle swarm intelligence technique and first-principles calculations, which were reported to have three-dimensional and four coordinated covalent diamond-like structures. These two new phases were calculated to be dynamically stable at zero and high pressures, and can be deduced from the previously reported Pmma phase by pressure-induced structural phase transitions. Read More

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February 2021

Indentation Induced Mechanical Behavior of Spark Plasma Sintered WC-Co Cemented Carbides Alloyed with CrC, TaC-NbC, TiC, and VC.

Authors:
Piotr Siwak

Materials (Basel) 2021 Jan 5;14(1). Epub 2021 Jan 5.

Faculty of Mechanical Engineering, Poznan University of Technology, 5 Marii Sklodowskiej-Curie Square, 60-965 Poznan, Poland.

The focus of this paper is on examining the mechanical behavior of spark plasma sintered WC-Co based composites doped with CrC, TaC-NbC, TiC, and VC, as well as defining some parameters characterizing deformation and fracture processes during hardness measurement. The calculated microhardness of WC-Co cemented carbides for all the studied compositions is found to be higher than the results obtained during hardness testing. Therefore, the ratio of the experimental and calculated values of microhardness is shown to be an approximate indication of WC-Co cemented carbide sensitivity to damage processes during indentation. Read More

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January 2021

Design, Synthesis, Molecular Modeling, Anticancer Studies, and Density Functional Theory Calculations of 4-(1,2,4-Triazol-3-ylsulfanylmethyl)-1,2,3-triazole Derivatives.

ACS Omega 2021 Jan 31;6(1):301-316. Epub 2020 Dec 31.

Chemistry Department, College of Sciences, Yanbu, Taibah University, Yanbu 30799, Saudi Arabia.

New conjugates of substituted 1,2,3-triazoles linked to 1,2,4-triazoles were synthesized starting from the appropriate S-propargylated 1,2,4-triazoles and . Ligation of 1,2,4-triazoles to the 1,2,3-triazole core was performed through Cu(I)-catalyzed cycloaddition of 1,2,4-triazole-based alkyne side chain and/or with several un/functionalized alkyl- and/or aryl-substituted azides to afford the desired 1,4-disubstituted 1,2,3-triazoles , using both classical and microwave methods. After their spectroscopic characterization (infrared, H, C nuclear magnetic resonance, and elemental analyses), an anticancer screening was carried out against some cancer cell lines including human colon carcinoma (Caco-2 and HCT116), human cervical carcinoma (HeLa), and human breast adenocarcinoma (MCF-7). Read More

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January 2021

Effects of laser debonding treatment on the optical and mechanical properties of all-ceramic restorations.

Lasers Med Sci 2021 Jan 15. Epub 2021 Jan 15.

Department of Stomatology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, 100730, China.

The objective of this study was to evaluate how erbium-doped yttrium aluminium garnet (Er:YAG) laser debonding treatment affects the optical and mechanical properties of dental ceramics. In total, 120 rectangular (22*5*1.2 mm) IPS E. Read More

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January 2021

Effect of light-curing time on microhardness of a restorative bulk-fill resin composite to lute CAD-CAM resin composite endocrowns.

Am J Dent 2020 Dec;33(6):331-336

Department of Cariology and Endodontology, University of Geneva, Geneva, Switzerland.

Purpose: To evaluate the minimal irradiation time to reach a sufficient polymerization of a photopolymerizable restorative bulk-fill resin composite to lute endocrowns.

Methods: A photopolymerizable restorative bulk-fill resin composite (Filtek One Bulk Fill) was submitted to direct light-curing by a high power LED light-curing unit for 20 seconds as the positive control group (n = 10). Five more test groups (n= 10) were light-cured in a natural tooth mold from three sites (buccal, palatal and occlusal) under a 9. Read More

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December 2020

Investigation of Formation Behaviour of Al-Cu Intermetallic Compounds in Al-50vol%Cu Composites Prepared by Spark Plasma Sintering under High Pressure.

Materials (Basel) 2021 Jan 7;14(2). Epub 2021 Jan 7.

Department of Materials System Engineering, Pukyong National University, Busan 48547, Korea.

Al-Cu matrix composites with excellent mechanical and thermal properties are among the most promising materials for realising high performance in thermal management systems. However, intermetallic compounds (ICs) formed at the Al/Cu interfaces prevent direct contact between the metals and severely deteriorate the thermal conductivity of the composite. In this study, we systemically investigated the formation behaviour of Al-Cu ICs as a function of compaction pressure at a low temperature of 380 °C. Read More

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January 2021

Influence of coloring liquid immersion on flexural strength, Vickers hardness, and color of zirconia.

J Prosthet Dent 2021 Jan 7. Epub 2021 Jan 7.

PhD student, Department of Prosthodontics, Faculty of Dentistry, Biruni University, İstanbul, Turkey.

Statement Of Problem: Zirconia is a widely used restorative material, yet its white color does not meet esthetic requirements and coloring is needed. However, the effects of different durations of coloring have not been thoroughly investigated.

Purpose: The purpose of this in vitro study was to evaluate the effects of coloring liquid immersion of different durations on the flexural strength, Vickers hardness, and color of zirconia. Read More

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January 2021

Physical and Mechanical Properties of Resins Blends Containing a Monomethacrylate with Low-polymerization Shrinkage.

Eur J Dent 2021 Feb 7;15(1):96-100. Epub 2021 Jan 7.

School of Dentistry, Santo Amaro University, São Paulo, SP, Brazil.

Objectives:  The aim of this study was to evaluate the Knoop hardness (KH), cross-link density (CLD), water sorption (WS), water solubility (WSB), and volumetric shrinkage (VS) of experimental resins blends containing a monomethacrylate with low-polymerization shrinkage.

Materials And Methods:  A blend of bisphenol glycidyl methacrylate (BisGMA) as base monomer was formulated with (Bis-GMA)/triethyleneglycol dimethacrylate (TEGDMA), Bis-GMA/isobornyl methacrylate (IBOMA), or Bis-GMA/TEGDMA/IBOMA in different concentrations (40, 50, or 60 wt%). The camphorquinone (CQ)/2-(dimethylamino) ethyl methacrylate (DMAEMA) was used as the photoinitiator system. Read More

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February 2021

Theoretical assessment of calix[4]arene-N-β-ketoimine (n=1-4) derivatives: Conformational studies, optoelectronic, and sensing of Cucation.

J Mol Model 2021 Jan 6;27(1):16. Epub 2021 Jan 6.

Laboratory of Advanced Materials and Interfaces (LIMA), Faculty of Science of Monastir, Avenue of Environnment, University of Monastir, 5000, Monastir, Tunisia.

Herein, we have investigated the key functions of the calix[4]arene, abbreviated as CX [1], and designed its several derivatives by substitution of the functional groups. Molecular geometry provides an intuitive understanding of the effect of functional groups on various physical properties. The addition of the N-β-ketoimine (n = 1-4) ligands has a direct effect on the stretching vibration of the H-bonding interaction. Read More

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January 2021

Application of the Entropy Weighted Water Quality Index (EWQI) and the Pollution Index of Groundwater (PIG) to Assess Groundwater Quality for Drinking Purposes: A Case Study in a Rural Area of Telangana State, India.

Arch Environ Contam Toxicol 2021 Jan 2;80(1):31-40. Epub 2021 Jan 2.

School of Water and Environment, Chang'an University, No. 126 Yanta Road, Xi'an, 710054, Shaanxi, China.

In this study, the quality of groundwater was assessed in a semi-arid region of India by using an entropy weighted water quality index (EWQI) and a pollution index of groundwater (PIG). The EWQI and PIG methods were used to evaluate data on physicochemical parameters in relation to drinking water quality standards. Groundwater samples were collected from the Dubbak region, Telangana state, India, and were analyzed for pH, total hardness, electrical conductivity, total dissolved solids, bicarbonate (HCO), chloride (Cl), sulfate (SO), nitrate (NO), fluoride (F), calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K). Read More

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January 2021

Multi-Layer Wear and Tool Life Calculation for Forging Applications Considering Dynamical Hardness Modeling and Nitrided Layer Degradation.

Materials (Basel) 2020 Dec 29;14(1). Epub 2020 Dec 29.

Institute of Metal Forming and Forming Machines, Leibniz University Hannover, 30823 Garbsen, Germany.

As one of the oldest shaping manufacturing processes, forging and especially hot forging is characterized by extreme loads on the tool. The thermal load in particular is able to cause constant changes in the hardness of the surface layer, which in turn has a decisive influence on the numerical estimation of wear. Thus, also during numerical wear, modeling hardness changes need to be taken into account. Read More

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December 2020

Forging of Mg-Al-Zn Magnesium Alloys on Screw Press and Forging Hammer.

Materials (Basel) 2020 Dec 23;14(1). Epub 2020 Dec 23.

Faculty of Mechanical Engineering, Lublin University of Technology, 20-618 Lublin, Poland.

Magnesium alloys are highly strain rate sensitive and exhibit good workability in a narrow forging temperature range. Consequently, parts made of these materials are usually forged with low-speed hydraulic presses, using specially designed tool heating systems in order to ensure near-isothermal conditions. This study investigates whether popular magnesium alloys such as Mg-Al-Zn can be forged in forging machines equipped with high-speed forming tools. Read More

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December 2020

Fluorescent Probe for Ag Detection Using SYBR GREEN I and C-C Mismatch.

Biosensors (Basel) 2020 Dec 24;11(1). Epub 2020 Dec 24.

Key Laboratory of the Three Gorges Reservoir Region's Eco-Environments of MOE, Chongqing University, Chongqing 400030, China.

Among heavy metals silver ions (Ag) severely impact water, the environment and have serious side effects on human health. This article proposes a facile and ultrasensitive fluorescent probe for the detection of Ag ions using SYBR Green I (SGI) and cytosine-rich (C-rich) silver-specific oligonucleotide (SSO). Maximum fluorescent intensities with the highest sensitivity were obtained using a 0. Read More

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December 2020

Evaluation of Synergic Potential of rGO/SiO as Hybrid Filler for BisGMA/TEGDMA Dental Composites.

Polymers (Basel) 2020 Dec 17;12(12). Epub 2020 Dec 17.

Engineer Abdullah Bugshan Research Chair for Dental and Oral Rehabilitation, College of Dentistry, King Saud University, Riyadh 11545, Saudi Arabia.

Graphene and graphene oxide based nanomaterials have attained immense significance in research because of their matchless physiochemical characteristics. Although potential biomedical applications of graphene have been extensively studied, however, dentistry related applications were rarely explored. This study aimed to investigate the effect of various percentages of surface modified reduce graphene oxide (S-rGO) in combination with SiO nanoparticles (bulk filler) on numerous physio-mechanical characteristics of acrylate-based (BisGMA/TEGDMA: 1:1 by wt. Read More

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December 2020

A League-Wide Evaluation of Factors Influencing Match Activity Profile in Elite Australian Football.

Front Sports Act Living 2020 6;2:579264. Epub 2020 Nov 6.

Institute for Health and Sport (iHeS), Victoria University, Melbourne, VIC, Australia.

Accurate interpretation of activity profile data requires an understanding of the variables influencing player movement during matches. Over 65,000 stints (player rotations) from all 207 matches of the 2018 Australian Football League (AFL) season were evaluated. The relative activity profile including total distance per minute (TD), high-speed running distance per minute (HSR) and Player Load per minute (PL) was determined for each stint and analysed against a range of match-related, player-related and environment-related predictor variables using multivariate linear mixed modelling. Read More

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November 2020