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Thermo physical Properties

Juan R Chamorro, Tyrel M McQueen
Ages of history are defined by the underlying materials that promoted human development: stone, bronze, and iron ages. Since the middle of the last century, humanity has lived in a silicon age, where the development of the transistor ushered in new technologies previously thought inconceivable. But as technology has advanced, so have the requirements for new materials to sustain increasing physical demands. The field of solid state chemistry is dedicated to the discovery of new materials and phenomena, and though most materials discoveries in history have been through serendipity rather than careful reaction design, the last few decades have seen an increase in the number of materials discovered through a consideration of chemical reaction kinetics and thermodynamics...
October 9, 2018: Accounts of Chemical Research
Ho Cm Brian, Otto Lt Lam, Nithya Jagannathan, Michael G Botelho
AIM: This article aims to systematically review the evidence reporting on physical properties of bonded amalgam, its clinical performance, and implications. MATERIALS AND METHODS: An electronic search in "Medline" (search term: Amalgam and Dentin bonding) from 1987 to 2013 yielded 465 publications out of which 170 articles were selected for the analysis. Data were extracted relating to the bond strength of amalgam to dentin, microleakage, postoperative sensitivity, and longevity of bonded amalgam restorations...
August 1, 2018: Journal of Contemporary Dental Practice
Kartikkumar Thakkar, Keyur Shah, Pravin Kodgire, Surendra Singh Kachhwaha
The present study demonstrates innovative and industrially viable in-situ biodiesel production process using coordinated ultrasound-microwave reactor. Reactive extraction process has been carried out by mixing grinded castor seeds with methanol in the presence of base catalyst (KOH). Response surface methodology coupled with central composite design has been applied for process optimization to achieve maximum yield. The result shows that maximum biodiesel yield of 93.5 ± 0.76% was obtained under favorable conditions of: molar ratio (350:1), catalyst (w/w) (1...
August 13, 2018: Ultrasonics Sonochemistry
Zhe Yang, Xuemei Han, Hiang Kwee Lee, Gia Chuong Phan-Quang, Charlynn Sher Lin Koh, Chee Leng Lay, Yih Hong Lee, Yue-E Miao, Tianxi Liu, In Yee Phang, Xing Yi Ling
Nanoporous gold (NPG) promises efficient light-to-heat transformation, yet suffers limited photothermal conversion efficiency owing to the difficulty in controlling its morphology for the direct modulation of thermo-plasmonic properties. Herein, we showcase a series of shape-controlled NPG nanoparticles with distinct bowl- (NPG-B), tube- (NPG-T) and plate-like (NPG-P) structures for quantitative temperature regulation up to 140 °C in <1 s using laser irradiation. Notably, NPG-B exhibits the highest photothermal efficiency of 68%, which is >12 and 39 percentage points better than those of other NPG shapes (NPG-T, 56%; NPG-P, 49%) and Au nanoparticles (29%), respectively...
August 30, 2018: Nanoscale
Zhijie Qin, Qiulin Yue, Yan Liang, Jingjing Zhang, Lin Zhou, Orlando Borrás Hidalgo, Xinli Liu
Quantum dots are important fluorescent semiconductor nano-crystals with distinguished electrical and optical properties and have gained great interest in many fields. The chemical and physical synthetic methods are usually not favorable for biological application due to high energy-consumption procedure and residual toxic chemicals. The development of novel "green" routes to prepare bio-compatible cadmium sulfide quantum dots constitutes a promising substituted approach. We used the white rot fungus Trametes versicolor for the biosynthesis of cadmium sulfide quantum dots taking account of the adsorption property of this fungus...
October 20, 2018: Journal of Biotechnology
Jinfu Zhao, Zhanqiang Liu, Qi Shen, Bing Wang, Qingqing Wang
Physical Vapor Deposition (PVD) Ti1- x Al x N coated cemented carbide tools are commonly used to cut difficult-to-machine super alloy of Inconel 718. The Al concentration x of Ti1- x Al x N coating can affect the coating microstructure, mechanical and thermo-physical properties of Ti1- x Al x N coating, which affects the cutting temperature in the machining process. Cutting temperature has great influence on the tool life and the machined surface quality. In this study, the influences of PVD (Ti,Al)N coated cemented carbide tools on the cutting temperature were analyzed...
July 25, 2018: Materials
Bui Quoc Bao, Ngoc Hoang Le, Diem Huong Tran Nguyen, Tuong Vi Tran, Linh Phuong Tran Pham, Long Giang Bach, Hieu Minh Ho, Thi Hiep Nguyen, Dai Hai Nguyen
The development of nanomaterials in the field of biomedical has attracted much attention in the past decades. New mesoporous nanosilica (MNS) generation, called multi functionalized MNS, presents the promising applications for efficient encapsulation, controlled release, and intracellular delivery of therapeutic agents due to their unique physiochemical properties, such as large surface area and pore volume, tunable particle size, biocompatibility, and high loading capacity. In this review, we intensively discussed the multi functionalized MNSs that respond to the demand of physical stimuli (thermo, light, magnetic field, ultrasound, and electricity), chemical stimuli (pH, redox, H2 O2 ), and biological stimuli (enzyme, glucose, ATP), individual or in combination...
October 1, 2018: Materials Science & Engineering. C, Materials for Biological Applications
G Montalbano, S Toumpaniari, A Popov, P Duan, J Chen, K Dalgarno, W E Scott, A M Ferreira
Hydrogels based on natural polymers offer a range of properties to mimic the native extracellular matrix, and provide microenvironments to preserve cellular function and encourage tissue formation. A tri-component hydrogel using collagen, alginate and fibrin (CAF) was developed and investigated at three collagen concentrations for application as a functional extracellular matrix analogue. Physical-chemical characterization of CAF hydrogels demonstrated a thermo-responsive crosslinking capacity at physiological conditions with stiffness similar to native soft tissues...
October 1, 2018: Materials Science & Engineering. C, Materials for Biological Applications
Jose M Ortiz-Roldan, Gustavo Esteban-Manzanares, Sergio Lucarini, Sofía Calero, Javier Segurado, Francisco Montero-Chacón, A Rabdel Ruiz-Salvador, Said Hamad
The development of new interatomic potentials to model metallic systems is a difficult task, due in part to the dependence between the parameters that describe the electron density and the short-range interactions. Parameter search methods are prone to false convergence. To solve this problem, we have developed a methodology for obtaining the electron density parameters independently of the short-range interactions, so that physically sound parameters can be obtained to describe the electron density, after which the short-range parameters can be fitted, thus reducing the complexity of the process and yielding better interatomic potentials...
July 11, 2018: Physical Chemistry Chemical Physics: PCCP
Hanna J M Wolff, Michael Kather, Hans Breisig, Walter Richtering, Andrij Pich, Matthias Wessling
Microgels are commonly synthesized in batch experiments, yielding quantities sufficient to perform characterization experiments for physical property studies. With increasing attention on the application potential of microgels, little attention is yet paid to the questions (a) whether they can be produced continuously on a larger scale, (b) whether synthesis routes can be easily transferred from batch to continuous synthesis, and (c) whether their properties can be precisely controlled as a function of synthesis parameters under continuous flow reaction conditions...
July 25, 2018: ACS Applied Materials & Interfaces
Kiersten M Ruff, Stefan Roberts, Ashutosh Chilkoti, Rohit V Pappu
Proteins and synthetic polymers can undergo phase transitions in response to changes to intensive solution parameters such as temperature, proton chemical potentials (pH), and hydrostatic pressure. For proteins and protein-based polymers, the information required for stimulus-responsive phase transitions is encoded in their amino acid sequence. Here, we review some of the key physical principles that govern the phase transitions of archetypal intrinsically disordered protein polymers (IDPPs). These are disordered proteins with repetitive amino acid sequences...
June 24, 2018: Journal of Molecular Biology
Yasmin Khambhaty, R Akshaya, C Rama Suganya, Kalarical Janardhanan Sreeram, Jonnalagadda Raghava Rao
Driven by the environmental benefits that bio-bleaching could bring, the interest in xylanase has received enormous attention and hence, the search of xylanase with properties like no cellulase activity, function at elevated temperatures and pH continues. The present study reports the production of extracellular xylanase from Aspergillus nidulans using waste agro-residues as substrate. The optimum temperature (60 °C) and pH (9.0), classified the xylanase as thermo and alkali tolerant. The addition of salt of Mn2+ increased the xylanase activity to almost double; however, these ions were unable to protect the enzyme from thermal inactivation...
October 15, 2018: International Journal of Biological Macromolecules
Ji Chen, Qiwei Hu, Leiming Fang, Duanwei He, Xiping Chen, Lei Xie, Bo Chen, Xin Li, Xiaolin Ni, Cong Fan, Akun Liang
Crystal solubility is one of the most important thermo-physical properties and plays a key role in industrial applications, fundamental science, and geoscientific research. However, high-pressure in situ measurements of crystal solubility remain very challenging. Here, we present a method involving high-pressure neutron diffraction for making high-precision in situ measurements of crystal solubility as a function of pressure over a wide range of pressures. For these experiments, we designed a piston-cylinder cell with a large chamber volume for high-pressure neutron diffraction...
May 2018: Review of Scientific Instruments
Na Sun, Panpan Sun, Aoli Wu, Xuanxuan Qiao, Fei Lu, Liqiang Zheng
Stimuli-responsive or "smart" soft materials have raised considerable attention due to their ability to spontaneously respond to external environmental variations and have a great potential for wide applications. Herein, a thermo/redox responsive hydrogel is facilely constructed based on a dual crosslinked matrix: the primary chemical crosslinked copolymer is composed of thermo-responsive poly(N-isopropylacrylamide) (PNIPAM) and poly(ionic liquid), and the secondary physical crosslinking component is generated by the ionic coordination between iron ions and carboxyl groups in the poly(ionic liquid)...
May 30, 2018: Soft Matter
Shakeel Ahmad Khandy, Ishtihadah Islam, Dinesh C Gupta, Amel Laref
Density functional theory (DFT)-based investigations have been put forward on the elastic, mechanical, and thermo-dynamical properties of BaPaO3 . The pressure dependence of electronic band structure and other physical properties has been carefully analyzed. The increase in Bulk modulus and decrease in lattice constant is seen on going from 0 to 30 GPa. The predicted lattice constants describe this material as anisotropic and ductile in nature at ambient conditions. Post-DFT calculations using quasi-harmonic Debye model are employed to envisage the pressure-dependent thermodynamic properties like Debye temperature, specific heat capacity, Grüneisen parameter, thermal expansion, etc...
May 7, 2018: Journal of Molecular Modeling
D Navarro-Urrios, N E Capuj, J Maire, M Colombano, J Jaramillo-Fernandez, E Chavez-Angel, L L Martin, L Mercadé, A Griol, A Martínez, C M Sotomayor-Torres, J Ahopelto
Silicon on insulator photonics has offered a versatile platform for the recent development of integrated optomechanical circuits. However, there are some constraints such as the high cost of the wafers and limitation to a single physical device level. In the present work we investigate nanocrystalline silicon as an alternative material for optomechanical devices. In particular, we demonstrate that optomechanical crystal cavities fabricated of nanocrystalline silicon have optical and mechanical properties enabling non-linear dynamical behaviour and effects such as thermo-optic/free-carrier-dispersion self-pulsing, phonon lasing and chaos, all at low input laser power and with typical frequencies as high as 0...
April 16, 2018: Optics Express
Syang-Peng Rwei, Huynh Nguyen Anh Tuan, Whe-Yi Chiang, Tun-Fun Way
A series of semi-interpenetrating polymer network (semi-IPN) hydrogels were synthesized and investigated in this study. Linear copolymer poly( N -isopropylacrylamide-co-itaconamic acid) p(NIPAM-co-IAM), which is formed by copolymerization of N -isopropylacrylamide (NIPAM) and itaconamic acid (IAM, 4-amino-2-ethylene-4-oxobutanoic acid), was introduced into a solution of NIPAM to form a series of pH and thermo dual-responsive p(NIPAM-co-IAM)/pNIPAM semi-IPN hydrogels by free radical polymerization. The structural, morphological, chemical, and physical properties of the linear copolymer and semi-IPN hydrogels were investigated...
April 28, 2018: Materials
Farhad Mohammadi, Soliman Mohammadi Samani, Nader Tanideh, Fatemeh Ahmadi
Purpose: Cartilage regeneration by using polymeric scaffolds is a new option for treatment of osteoarthritis. A good scaffold for tissue engineering should copy the characteristics of natural extracellular matrix. The purpose of this study was to make a dosage form with proper reliability and stability for cartilage repair. Methods: Hybrid scaffolds containing different ratios of hyaluronic acid (HA) and collagen were prepared and loaded with prednisolone as anti-inflammatory agent. Two different dosage forms (lyophilized implantable disk and thermo-sensitive gels) were examined...
March 2018: Advanced Pharmaceutical Bulletin
T R Pavlov, T Wangle, M R Wenman, V Tyrpekl, L Vlahovic, D Robba, P Van Uffelen, R J M Konings, R W Grimes
Values are presented for thermal conductivity, specific heat, spectral and total hemispherical emissivity of ThO2 (a potential nuclear fuel material) in a temperature range representative of a nuclear accident - 2000 K to 3050 K. For the first time direct measurements of thermal conductivity have been carried out on ThO2 at such high temperatures, clearly showing the property does not decrease above 2000 K. This could be understood in terms of an electronic contribution (arising from defect induced donor/acceptor states) compensating the degradation of lattice thermal conductivity...
March 22, 2018: Scientific Reports
Omer Said Toker, Nevzat Konar, Ibrahim Palabiyik, Haniyeh Rasouli Pirouzian, Sirin Oba, Derya Genc Polat, Ender Sinan Poyrazoglu, Osman Sagdic
In this study, dark chocolate enriched with EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) was developed using various forms and origins. Quality characteristics such as physical, thermo-gravimetric, rheological, textural and sensory properties of chocolates were investigated. The highest EPA/DHA stability was determined in samples prepared by free-flowing powder and microencapsulated forms of omega-3 fatty acids (FA). The L∗ and C∗ values varied from 32.16-33.37 and 7.45-8.09, respectively for the all samples...
July 15, 2018: Food Chemistry
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