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bond strength

Evgenii Stoyanov, Irina S Stoyanova
Experimental study on protonation of simple weakly basic molecules (L) by the strongest solid superacid, H(CHB11F11), showed that basicity of SO2 is high enough (during attachment to the acidic H atoms at partial pressure of 1 atm) to break the bridged H-bonds of the polymeric acid and to form a mixture of solid mono- and disolvates, LH+‧‧‧An- and L-H+-L. With a decrease in the basicity of L = CO (via C), N2O, and CO (via O), only proton monosolvates are formed, which approach L-H+-An species with convergence of the strengths of bridged H-bonds...
February 19, 2018: Angewandte Chemie
Marcelle Gonçalves Garcia, Laiza Tatiana Poskus, Viviane Hass, Cristiane Mariote Amaral, Jaime Dutra Noronha-Filho, Eduardo Moreira da Silva
PURPOSE: To investigate the effect of Ca(OH)2 concentration on pH neutralization, degree of conversion (DC%), and bonding performance of experimental self-etch adhesives (SEAs). MATERIALS AND METHODS: Four different concentrations of Ca(OH)2 (0 wt%, 1 wt%, 2 wt%, and 4 wt%) were added to the bond of an experimental two-step SEA consisting of primer (10-MDP [30 wt%], TEG-DMA [30 wt%], ethanol [35 wt%], water [5 wt%], camphorquinone [0.5 wt%], and tertiary amine [0...
February 16, 2018: Journal of Adhesive Dentistry
Wei Zhang, Xin Jin, Heng Li, Run-Run Zhang, Cheng-Wei Wu
Hydrogels based on chitosan/hyaluronic acid/β-sodium glycerophosphate demonstrate injectability, body temperature sensitivity, pH sensitive drug release and adhesion to cancer cell. The drug (doxorubicin) loaded hydrogel precursor solutions are injectable and turn to hydrogels when the temperature is increased to body temperature. The acidic condition (pH 4.00) can trigger the release of drug and the cancer cell (Hela) can adhere to the surface of the hydrogels, which will be beneficial for tumor site-specific administration of drug...
April 15, 2018: Carbohydrate Polymers
Hongjuan Geng
This work reports a "one-step" approach to make cellulose-based hydrogels in NaOH/urea aqueous solution via mixing N,N'-methylene bisacrylamide (MBA) with cellulose solution at room temperature. The hydrogels were revealed to be formed by an addition reaction between the double bonds of MBA and the hydroxyl groups of cellulose. Two states of hydrogels, i.e. the freshly prepared hydrogels and the hydrogels at swelling equilibrium state in deionized water, were prepared. Water retention of the hydrogels can reach up to 330 g H2 O/g dry hydrogel...
April 15, 2018: Carbohydrate Polymers
Yadong Sun, Jiyou Gu, Haiyan Tan, Yanhua Zhang, Pengfei Huo
Starch-based adhesives were prepared by esterification modification with dodecenyl succinic anhydride (DDSA) and polyaryl polymethylene isocyanate (PAPI) as a crosslinking agent. DDSA modified starch (DMS) adhesives could significantly enhance the viscosity and adhesion strength of starch adhesives, making it beneficial to be applied in the field of plywood industry. This paper investigated the physicochemical properties of starch modified by dodecenyl succinic anhydride. Solid content, viscosity, adhesion, structural change and morphological features were characterized in detail...
February 15, 2018: International Journal of Biological Macromolecules
Fuzheng Ren, Hanjing Sun, Lin Cui, Yike Si, Ning Chen, Guobin Ren, Qiufang Jing
Drugs in amorphous solid dispersions (ASDs) are highly dispersed in hydrophilic polymeric carriers, which also help to restrain recrystallization and stabilize the ASDs. In this study, microscopic observation after antisolvent recrystallization was developed as a rapid screening method to select appropriate polymers for the initial design filgotinib (FTN) ASDs. Using solvent evaporation, FTN ASDs with the polymers were prepared, and accelerated experimentation validated this screening method. Fourier-transform infrared spectroscopy, Raman scattering, and nuclear magnetic resonance revealed hydrogen-bonding formation in the drug-polymer binary system, which was critical for ASDs stabilization...
February 15, 2018: Journal of Pharmaceutical Sciences
Putsadeeporn Thammajaruk, Masanao Inokoshi, Shanley Chong, Massimiliano Guazzato
OBJECTIVES: The aim of this study was to systematically review the literature and statistically analyze bond strength data to identify the influence that composite cements, type of test methodology, chemical and mechanical pre-treatments have on the bond strength of composite cements to zirconia in three different artificial aging conditions. METHODS: The literature was electronically searched in MEDLINE, PUBMED, EMBASE, and SCOPUS to select relevant articles that evaluated the bond strength between zirconia and composite cements...
February 8, 2018: Journal of the Mechanical Behavior of Biomedical Materials
GeunSeok Yoon, Sang-Min Park, Heuiwon Yang, Daniel C W Tsang, Daniel S Alessi, Kitae Baek
During the measurement of total organic carbon (TOC), dissolved organic carbon is converted into CO 2 by using high temperature combustion (HTC) or wet chemical oxidation (WCO). However, the criteria for selecting the oxidation methods are not clear. In this study, the chemical structures of organic material were considered as a key factor to select the oxidation method used. Most non-degradable organic compounds showed a similar oxidation efficiency in both methods, including natural organic compounds, dyes, and pharmaceuticals, and thus both methods are appropriate to measure TOC in waters containing these compounds...
February 12, 2018: Chemosphere
Shubhra Sarkar, Nagarajan Ramanathan, Kalyanasundaram Sundararajan
Hydrogen bonded interactions of pyrrole with water and methanol have been studied using matrix isolation infrared spectroscopy and compared with the calculation performed on dimethyl ether. Computations carried out at MP2/aug-cc-pVDZ level of theory yielded two minima for the pyrrole-water and pyrrole-methanol complexes. The global and local minima correspond to the N-H∙∙∙O and O-H∙∙∙π complexes, respectively, where the N-H group of pyrrole interacts with oxygen of water/methanol and O-H of water and methanol interacts with the π cloud of pyrrole...
February 16, 2018: Journal of Physical Chemistry. A
Kaho Yamaguchi, Kazuma Yamawaki, Takuya Kimura, Junpei Kuwabara, Takeshi Yasuda, Yoshinobu Nishimura, Takaki Kanbara
The cationic Pt complexes with amide groups have been found to show dimer emission through hydrogen bonding interactions with counter anions even at low concentration. In order to investigate further details of dimer emission, we prepared three Pt complexes, Pt·B(C6F5)4, Pt·Cl, and Pt·PF6, whose counter anions possess different strengths of a hydrogen bonding acceptor. Hydrogen bonding interactions in the ground state and excited-state dynamics of the Pt complexes were evaluated by NMR analysis, temperature dependence, and kinetics of dimer emission...
February 16, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Qianmin Ou, Ya Hu, Siqi Yao, Yan Wang, Xuefeng Lin
OBJECTIVES: This study investigated the effect of matrix metalloproteinase 8 (MMP-8) on resin-dentin bonds, assessed the mechanical properties of the interfaces over time, and discussed the potential application of MMP-8 inhibitor I (MMP8-I) as a specific MMP-8 inhibitor to be incorporated into dental adhesives. METHODS: The activation and inhibition of MMP-8 was detected by colorimetric assay. After 1 day, 6 months and 1 year of storage of Control, MMP8-I, and chlorhexidine (CHX) groups, the microtensile bond strengths (μTBS) were used to evaluate the bond strength and failure mode distributions, and nanoleakage analysis was used to evaluate the minor scattered silver particles...
February 12, 2018: Dental Materials: Official Publication of the Academy of Dental Materials
Fan Zhao, Wei Jin, Lin Ma, Jian-Ye Zhang, Jin-Long Wang, Jing-Hai Zhang, Yong-Bo Song
Voltage-gated sodium (Na v ) channels play a pivotal role for the changes in membrane potential and belong to large membrane proteins that compose four voltage sensor domains (VSD1-4). In this study we describe the binding mode and selectivity of one of the aryl sulfonamide sodium channel inhibitors, PF-04856264, for the VSD4s in Na v 1.4, Na v 1.5 and Na v 1.7, respectively, through molecular dynamics simulation and enhanced post-dynamics analyses. Our results show that there are three binding site regions (BSR1-3) in the combination of the ligand and receptors, of which BSR1 and BSR3 contribute to the selectivity and affinity of the ligand to the receptor...
February 15, 2018: Journal of Biomolecular Structure & Dynamics
Seong-Hee Lee, Jung-Han Kim, Hyo-Sang Yoo, Hyeon-Taek Son
Accumulative roll-bonding (ARB) is the most appropriate process for sheet-shaped materials because it can be carried out readily by utilizing the conventional rolling apparatus. In this study, a nanostructured AA1050/AA5052 Al alloy sheet was successfully fabricated by four-layer stack ARB process. The ARB of AA1050 and AA5052 alloy sheets was performed up to 6 cycles without a lubricant at ambient temperature. The sample fabricated by the ARB was a multi-layer aluminum alloy sheet in which AA1050 and AA5052 layers are alternately stacked...
March 1, 2018: Journal of Nanoscience and Nanotechnology
Chang-Been Lee, Seong-Sik Bang, Young-Chul Park, Jee Hun Kim, Nam-Seok Kim, Seung-Ho Yang, Jae-Sung Park, Jong-Bae Kim, Dong-Ho Choi, Soonwan Chung, Changjae Kim, Taek-Kyun Jung, Soong-Keun Hyun
The surface activated bonding (SAB) method generally has the advantage of high bonding strength, low contact resistance, and high microstructural stability at room temperature. In this study, Ti-Al laminates were produced by surface activated bonding with aluminum and titanium foils. Heat treatment was conducted at the temperature range from 200 to 550 °C in vacuum. The bonding strength Ti-Al laminates was measured by a peel test, and the interfacial characteristics were investigated microstructural observation...
March 1, 2018: Journal of Nanoscience and Nanotechnology
Sung-Min Kwon, Bong Ki Min, Jun Sik Son, Tae-Yub Kwon
Self-assembled monolayers of thiols have been used to link a range of materials to planar gold surfaces or gold nanoparticles in nanoscience and nanotechnology. Novel mercapto silane systems are a promising alternative to dental noble metal alloys for enhanced resin bonding durability Goldbased alloys for full-cast restorations contain various base metal elements, which may bond to acidic functional monomers chemically, in addition to noble metal elements. This study examined how the additional incorporation of a phosphate monomer (di-2-hydroxyethyl methacryl hydrogenphosphate, DHP) into novel mercapto silane primer systems affected the resin bond strength to a type IV gold alloy pretreated with the primers...
February 1, 2018: Journal of Nanoscience and Nanotechnology
Ramin Atash, Antoaneta Yordanova, Sibel Cetik
PURPOSE: The aim of this study was to investigate the effect of coloring on the interfacial surface adhesion between a zirconia framework and ceramic veneer using three-point flexural bonding strength. MATERIALS AND METHODS: A total of 40 zirconia bars (Zirlux ST1; DE Healthcare) were cut and divided into two groups of 20 (Groups 1 and 2). The two groups were then further split and divided into four groups of 10 each (Groups 1a, 1b, 2a, and 2b). Groups 1a and 1b tested adhesion of uncolored zirconia and two different shades of ceramic veneer, and Groups 2a and 2b tested adhesion of zirconia colored with two different coloring liquids and one shade of ceramic veneer...
February 15, 2018: International Journal of Prosthodontics
Zhengmu Wang, Hongbin Zhang, Axel J Chu, John Jackson, Karen Lin, Chinten James Lim, Dirk Lange, Mu Chiao
Well-organized composite formations such as hierarchical nested-network (NN) structure in bone tissue and reticular connective tissue present remarkable mechanical strength and play a crucial role in achieving physical and biological functions for living organisms. Inspired by these delicate microstructures in nature, an analogous scaffold of double network hydrogel was fabricated by creating a poly(2-hydroxyethyl methacrylate) (pHEMA) network in the porous structure of alginate hydrogels. The resulting hydrogel possessed hierarchical NN structure and showed significantly improved mechanical strength but still maintained high elasticity comparable to soft tissues due to a mutual strengthening effect between the two networks...
February 12, 2018: Acta Biomaterialia
Christopher R Taylor, Graeme M Day
We present a periodic density functional theory study of the stability of 350 organic cocrystals relative to their pure single-component structures, the largest study of cocrystals yet performed with high-level computational methods. Our calculations demonstrate that cocrystals are on average 8 kJ mol -1 more stable than their constituent single-component structures and are very rarely (<5% of cases) less stable; cocrystallization is almost always a thermodynamically favorable process. We consider the variation in stability between different categories of systems-hydrogen-bonded, halogen-bonded, and weakly bound cocrystals-finding that, contrary to chemical intuition, the presence of hydrogen or halogen bond interactions is not necessarily a good predictor of stability...
February 7, 2018: Crystal Growth & Design
T P Hou, K M Wu, W M Liu, M J Peet, C N Hulme-Smith, L Guo, L Zhuang
Understanding the nature of the magnetic-field-induced precipitation behaviors represents a major step forward towards unravelling the real nature of interesting phenomena in Fe-based alloys and especially towards solving the key materials problem for the development of fusion energy. Experimental results indicate that the applied high magnetic field effectively promotes the precipitation of M 23 C 6 carbides. We build an integrated method, which breaks through the limitations of zero temperature and zero external field, to concentrate on the dependence of the stability induced by the magnetic effect, excluding the thermal effect...
February 14, 2018: Scientific Reports
Luo Zhanjun, Chen Hui, Wu Jing, Xia Xiaohong, Liu Hongbo, Yang Li
The homogeneous carbon nanotubes (CNTs) directly grown on short cut carbon fibers (CFs) surface by chemical vapor deposition (CVD) using iron nanoparticles as catalyst. The iron nanoparticles were obtained by the reduction of magnetite particles using mixed nitrogen and hydrogen gas flow at 415 °C. Magnetite particles were prepared through a solvothermal reaction, where iron(III) acetylacetone as catalyst source and polylol as solvent. CNTs grown on CFs were used as reinforcement in epoxy (EP). The effects of density of CNTs grown on CFs (CNTs-CFs) and different mass fractions of CNTs-CFs in EP on the composites flexural strength were investigated...
July 1, 2018: Journal of Nanoscience and Nanotechnology
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