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bond strength

Essam Hammam, Jalal Basahi, Iqbal Ismail, Ibrahim Hassan, Talal Almeelbi
The excited state hydrogen bonding dynamics of BBVN in hydrogen donating methanol solvent was explored at the TD-BMK/cc-pVDZ level of theory with accounting for the bulk environment effects at the polarizable continuum model (PCM). The heteroatoms of the BBVN laser dye form hydrogen bonds with four methanol molecules. In the formed BBVN-(MeOH)4 complex, the A-type hydrogen bond (N…HO), of an average strength of 25kJmol(-1), is twofold stronger than the B-type (O…HO) one. Upon photon absorption, the total HB binding energy increases from 78...
October 17, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Fengbo Zhu, Libo Cheng, Jun Yin, Ziliang Wu, Jin Qian, Jianzhong Fu, Qiang Zheng
Polyion complex (PIC) hydrogels have been proposed as promising engineered soft materials due to their high toughness and good processibility. In this work, we reported manufacturing of complex structures with tough PIC hydrogels based on three-dimensional (3D) printing technology. The strategy relies on the distinct strength of ionic bonding in PIC hydrogels at different stages of printing. In concentrated saline solution, PIC forms viscous solution, which can be directly extruded out of a nozzle into water, where dialyzing out of salt and counterions results in sol-gel transition to form tough physical PIC gel with intricate structures...
October 25, 2016: ACS Applied Materials & Interfaces
Kalyan Kong, Noriko Hiraishi, Mohannad Nassar, Masayuki Otsuki, Cynthia K Y Yiu, Junji Tagami
PURPOSE: Phytic acid (IP6) works well as an etchant in dentin bonding to remove the smear layer due to its acidity and chelating effect. This study compared the etching effect of IP6 with phosphoric acid (PA) and ethylenediaminetetraacetic acid (EDTA) on resin-dentin bond strength, micromorphology of the etched dentin surface and nanoleakage formation along resin-dentin interfaces and compared the protecting effect against collagen degradation. METHODS: Dentin disks and flat dentin surfaces were obtained from extracted human teeth...
October 21, 2016: Journal of Prosthodontic Research
Man Zhang, Rui Wang, Zhenqiang Shi, Xuelian Huang, Weifeng Zhao, Changsheng Zhao
A novel family of multi-responsive, tough, and reversible hydrogels were prepared by the combination of dipole-dipole interaction, hydrogen bonding interaction and slightly chemical cross-linking, using monomers of acrylonitrile, sodium allylsulfonate and itaconic acid. Reversible gel-sol transition was achieved by the flexible conversion of the dipole-dipole interactions between acrylonitrile-acrylonitrile and acrylonitrile-sodium thiocyanate, and the hydrogels could freely form desired shapes. The dipole-dipole and hydrogen bonding interactions improved the mechanical strength of the hydrogels with a compressive stress of 2...
October 11, 2016: Journal of Hazardous Materials
Ming Guo, Xiaowang Lu, Yan Wang, Peter E Brodelius
The binding properties of pentacyclic triterpenoid isomeric drugs, i.e. ursolic acid (UA) and oleanolic acid (OA), to bovine lactoferrin (BLF) have been studied by molecule modeling, fluorescence spectroscopy, UV-visible absorbance spectroscopy and infrared spectroscopy (IR). Molecular docking, performed to reveal the possible binding mode or mechanism, suggested that hydrophobic interaction and hydrogen bonding play important roles to stabilize the complex. The results of spectroscopic measurements showed that the two isomeric drugs both strongly quenched the intrinsic fluorescence of BLF through a static quenching procedure although some differences between UA and OA binding strength and non-radiation energy transfer occurred within the molecules...
October 18, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Alex Dickson, Christopher T Bailey, John Karanicolas
Proteins can be destabilized by a number of environmental factors such as temperature, pH, and mutation. The ability to subsequently restore function under these conditions by adding small molecule stabilizers, or by introducing disulfide bonds, would be a very powerful tool, but the physical principles that drive this stabilization are not well understood. The first problem lies is in choosing an appropriate binding site or disulfide bond location to best confer stability to the active site and restore function...
October 24, 2016: Journal of Computational Chemistry
Renato Cassio Roperto, Thiago Soares Porto, Lisa Lang, Sorin Teich, Sean Weber, Omar El-Mowafy, Sizenando Toledo Porto-Neto
During a fiber post cementation, bonding failure often occurs at the junction between the fiber-post and resin-cement. Because this failure requires better characterization, we evaluated if different post surface treatment can affect the bond strength of urethane dimethacrylate (UDMA) fiber-posts with resin-cements. Three groups were created: G1: no treatment/silane; G2: ethyl alcohol (96° GL)/silane; G3: 24% H2O2/silane and further divided into four subgroups: I-Unicem/3MESPE; II-BisCem/Bisco; III-Panavia SA/Kuraray and IV-DuoLink/Bisco...
October 22, 2016: Dental Materials Journal
Ion N Mihailescu, Dorota Bociaga, Gabriel Socol, George E Stan, Mariana-Carmen Chifiriuc, Coralia Bleotu, Marius A Husanu, Gianina Popescu-Pelin, Liviu Duta, Catalin R Luculescu, Irina Negut, Claudiu Hapenciuc, Cristina Besleaga, Irina Zgura, Florin Miculescu
We report on the selection by combinatorial pulsed laser deposition of Silver-doped Carbon structures with reliable physical-chemical characteristics and high efficiency against microbial biofilms. The investigation of the films was performed by scanning electron microscopy, high resolution atomic force microscopy, energy dispersive X-Ray Spectroscopy, X-ray diffraction, Raman spectroscopy, bonding strength "pull-out" tests, and surface energy measurements. In vitro biological assays were carried out using a large spectrum of bacterial and fungal strains, i...
October 20, 2016: International Journal of Pharmaceutics
Isil Cekic-Nagas, Gulfem Ergun, Ferhan Egilmez, Pekka Kalevi Vallittu, Lippo Veli Juhana Lassila
PURPOSE: The aim of this study was to evaluate the effects of hydrofluoric acid treatment on bond strength of resin cements to three different types of ceramic/glass containing CAD-CAM block composite materials. METHODS: CAD-CAM block materials of polymer infiltrated (Vita Enamic), resin nanoceramic (Lava Ultimate) and nanoceramic (Cerasmart) with a thickness of 1.5mm were randomly divided into two groups according to the surface treatment performed. In Group 1, specimens were wet-ground with silicon carbide abrasive papers up to no...
March 10, 2016: Journal of Prosthodontic Research
Qian Wang, Xiaoguang Chen, Lin Zhu, Jiuchun Yan, Zhiwei Lai, Pizhi Zhao, Juncheng Bao, Guicai Lv, Chen You, Xiaoyu Zhou, Jian Zhang, Yuntao Li
Al-50Si alloys were joined by rapid ultrasound-induced transient-liquid-phase bonding method using Zn foil as interlayer at 390°C in air, below the melt point of interlayer. The fracture of oxide films along the edge of Si particles led to contact and inter-diffusion between aluminum substrate and Zn interlayer, and liquefied Zn-Al alloys were developed. The width of Zn-Al alloys gradually decreased with increasing the ultrasonic vibration time due to liquid squeezing out and accelerated diffusion. A stage of isothermal solidification existed, and the completion time was significantly shortened...
January 2017: Ultrasonics Sonochemistry
Evelise M Souza, Jan De Munck, Pong Pongprueksa, Annelies Van Ende, Bart Van Meerbeek
OBJECTIVES: To determine the interfacial fracture toughness (iFT) and micro-tensile strength (μTBS) of composite cements bonded to dentin. METHODS: Fifty feldspar ceramic blocks (Vita Mark II, Vita Zahnfabrik) were luted onto dentin using two self-adhesive (G-CEM LinkAce, GC; SpeedCEM, Ivoclar Vivadent), two self-etch (Multilink Primer & Multilink Automix, Ivoclar Vivadent; Scotchbond Universal & RelyX Ultimate, 3 M ESPE), and one etch-and-rinse (Excite F DSC & Variolink II, Ivoclar Vivadent) composite cement (n=10)...
October 19, 2016: Dental Materials: Official Publication of the Academy of Dental Materials
Toshiki Miyazaki, Chisato Matsunami, Yuki Shirosaki
Polyetheretherketone (PEEK) has attracted much attention as an artificial intervertebral spacer for spinal reconstruction. Furthermore, PEEK plastic reinforced with carbon fiber has twice the bending strength of pure PEEK. However, the PEEK-based materials do not show ability for direct bone bonding, i.e., bioactivity. Although several trials have been conducted for enabling PEEK with bioactivity, few studies have reported on bioactive surface modification of carbon-PEEK composites. In the present study, we attempted the preparation of bioactive carbon-PEEK composites by chemical treatments with H2SO4 and CaCl2...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Stephanie Lemos Martins Sicuro, Marilisa Carneiro Leão Gabardo, Carla Castiglia Gonzaga, Nathaly Dias Morais, Flares Baratto-Filho, Gisele Maria Correr Nolasco, Denise Piotto Leonardi
INTRODUCTION: Different materials have been used for intervening in root perforations. These materials are often in contact with resin cements used for cementation of intraradicular retainers. The aim of this study was to evaluate the bond strength of self-adhesive resin cement to different materials used to treat root perforations (mineral trioxide aggregate [MTA], Portland cement [PORT], and glass ionomer cement [GIC]). METHODS: Four discs (10 × 1 mm) of each material (the MTA, PORT, and GIC groups) were embedded into polyvinyl chloride tubes using acrylic resin, ground, and polished until a flat surface was exposed...
October 18, 2016: Journal of Endodontics
Chencheng Sun, Bowen Xiong, Yang Pan, Hao Cui
Polyaniline (PANI) prepared by chemical oxidation was studied for adsorption removal of tannic acid (TA) from aqueous solution. Batch adsorption studies were carried out under different adsorbent dosages, pH, ionic strength, initial TA concentration and coexisting anions. Solution pH had an important impact on TA adsorption onto PANI with optimal removal in the pH range of 8-11. TA adsorption on PANI at three ionic strength levels (0.02, 0.2 and 2molL(-1) NaCl) could be well described by Langmuir model (monolayer adsorption process) and the maximum adsorption capacity was 230, 223 and 1023mgg(-1), respectively...
October 15, 2016: Journal of Colloid and Interface Science
Maria Demireva, JungSoo Kim, P B Armentrout
Guided ion beam mass spectrometry (GIBMS) is used to measure the kinetic energy dependent product ion cross sections for reactions of the lanthanide metal gadolinium cation (Gd(+)) with O2, CO2, and CO and for reactions of GdO(+) with CO, O2, and Xe. GdO(+) is formed through barrierless and exothermic processes in the reactions of Gd(+) with O2 and CO2. All other reactions observed are endothermic, and analyses of their kinetic energy dependent cross sections yield 0 K bond dissociation energies (BDEs) for GdO(+), GdC(+), and GdCO(+)...
October 21, 2016: Journal of Physical Chemistry. A
Erfan Dashtimoghadam, Ghasem Bahlakeh, Hamed Salimi-Kenari, Mohammad Mahdi Hasani-Sadrabadi, Hamid Mirzadeh, Bo Nyström
The temperature-induced gelation of chitosan/glycerophosphate (Chs/GP) systems through physical interactions has shown great potential for various biomedical applications. In the present work, hydroxyethyl cellulose (HEC) was added to the thermosensitive Chs/GP solution to improve the mechanical strength and gel properties of the incipient Chs/HEC/GP gel in comparison with the Chs/GP hydrogel at body temperature. The physical features of the macromolecular complexes formed by the synergistic interaction between chitosan and hydroxyethyl cellulose in the presence of β-glycerophosphate disodium salt solution have been studied essentially from a rheological point of view...
October 21, 2016: Biomacromolecules
Qinghua Xu, Chaoliang He, Zhen Zhang, Kaixuan Ren, Xuesi Chen
Injectable hydrogels have been widely investigated in biomedical applications, and increasing demand has been proposed to achieve the dynamic regulation of physiological properties of hydrogels. Herein, a new type of injectable and biomolecule-responsive hydrogel based on poly(L-glutamic acid) (PLG) grafted with disulfide bond modified phloretic acid (denoted as PLG-g-CPA) was developed. The hydrogels formed in situ via enzymatic crosslinking under physiological condition in the presence of horseradish peroxidase and hydrogen peroxide...
October 20, 2016: ACS Applied Materials & Interfaces
Woon Yong Sohn, Valérie Brenner, Eric Gloaguen, Michel Mons
Conformer-selective IR gas phase spectroscopy and high level quantum chemistry methods have been used to characterise the diversity of local NH-π interactions between the π ring of a phenylalanine aromatic residue and the nearby main chain amide groups. The study of model systems shows how the amide NH stretch vibrational features, in the 3410-3460 cm(-1) frequency range, can be used to monitor the strength of these local π H-bonds, which is found to depend on both the backbone conformation and the aromatic side chain orientation...
October 20, 2016: Physical Chemistry Chemical Physics: PCCP
Rahul Shukla, Deepak Chopra
In this article, the existence of NO noncovalent interactions was explored in per-halo substituted ammonia-water complexes. Optimized geometry at the MP2/aug-cc-pVTZ level shows that the NO distance in all complexes is less than the sum of the vdW radii of N and O. The strength of these contacts was directly dependent on the extent of chlorine substitution on N or O atoms. Also, the level of theory and the basis set employed for the binding energy calculations have a direct effect on the strength of the NO contacts...
October 20, 2016: Physical Chemistry Chemical Physics: PCCP
Fredrik Elinder, Michael Madeja, Hugo Zeberg, Peter Århem
The transmembrane voltage needed to open different voltage-gated K (Kv) channels differs by up to 50 mV from each other. In this study we test the hypothesis that the channels' voltage dependences to a large extent are set by charged amino-acid residues of the extracellular linkers of the Kv channels, which electrostatically affect the charged amino-acid residues of the voltage sensor S4. Extracellular cations shift the conductance-versus-voltage curve, G(V), by interfering with these extracellular charges...
October 18, 2016: Biophysical Journal
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