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https://www.readbyqxmd.com/read/28646753/mechanical-properties-and-molecular-structure-analysis-of-subsurface-dentin-after-er-yag-laser-irradiation
#1
Zhengdi He, Lingling Chen, Xuejuan Hu, Yasushi Shimada, Masayuki Otsuki, Junji Tagami, Shuangchen Ruan
The purpose of this study was to evaluate the chemical and mechanical modifications in subsurface dentin layer after Er: YAG (Erbium-Yttrium Aluminium Garnet) laser irradiation, as the guidance of new dental restorative materials specific for laser irradiated dentin. MATERIALS AND METHODS: Dentin disks obtained from extracted human molars were prepared and exposed to a single pulse Er:YAG laser irradiation at 80mJ/pulse. After laser irradiation the mechanical and chemical characteristics of intertubular dentin in subsurface layer were studied using nanoindentation tester and micro-Raman spectromy (μ-RS)...
June 3, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28634498/evaluation-of-in-vitro-cytotoxicity-biocompatibility-and-changes-in-the-expression-of-apoptosis-regulatory-proteins-induced-by-cerium-oxide-nanocrystals
#2
Shahanavaj Khan, Anees A Ansari, Christian Rolfo, Andreia Coelho, Maha Abdulla, Khayal Al-Khayal, Rehan Ahmad
Cerium oxide nanocrystals (CeO2-NCs) exhibit superoxide dismutase and catalase mimetic activities. Based on these catalytic activities, CeO2-NCs have been suggested to have the potential to treat various diseases. The crystalline size of these materials is an important factor that influences the performance of CeO2-NCs. Previous reports have shown that several metal-based nanocrystals, including CeO2-NCs, can induce cytotoxicity in cancer cells. However, the underlying mechanisms have remained unclear. To characterize the anticancer activities of CeO2-NCs, several assays related to the mechanism of cytotoxicity and induction of apoptosis has been performed...
2017: Science and Technology of Advanced Materials
https://www.readbyqxmd.com/read/28633527/molecular-beam-epitaxy-of-highly-crystalline-monolayer-molybdenum-disulfide-on-hexagonal-boron-nitride
#3
Deyi Fu, Xiaoxu Zhao, Yu-Yang Zhang, Linjun Li, Hai Xu, A-Rang Jang, Seong In Yoon, Peng Song, Sock Mui Poh, Tianhua Ren, Zijing Ding, Wei Fu, Tae Joo Shin, Hyeon Suk Shin, Sokrates T Pantelides, Wu Zhou, Kian Ping Loh
Atomically thin molybdenum disulfide (MoS2), a direct-band-gap semiconductor, is promising for applications in electronics and optoelectronics but the scalable synthesis of highly-crystalline film remains challenging. Here we report the successful epitaxial growth of a continuous, uniform, highly-crystalline monolayer MoS2 film on hexagonal boron nitride (h-BN) by molecular beam epitaxy. Atomic force microscopy and electron microscopy studies reveal that MoS2 grown on h-BN primarily consists of two types of nucleation grains (0o aligned and 60o anti-aligned domains)...
June 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28628483/sige-layer-thickness-effect-on-the-structural-and-optical-properties-of-well-organized-sige-sio2-multilayers
#4
Eliana Vieira, Johann Toudert, Anabela Gomes Rolo, Andrea Parisini, Joaquim Leitão, Maria Rosario Correia, Nuno Franco, Eduardo Alves, Adil Chahboun, Javier Martin-Sanchez, Rosalia Serna, Maria de Jesus de Matos Gomes
In this work, we report on the production of regular (SiGe/SiO2)20 multilayer structures by conventional RF-magnetron sputtering, at 350 ºC. Transmission electron microscopy, scanning transmission electron microscopy, raman spectroscopy, and X-ray reflectometry measurements revealed that annealing at a temperature of 1000 ºC lead to the formation of SiGe nanocrystals between SiO2 thin layers with good multilayer stability. Reducing the nominal SiGe layer thickness (tSiGe) from 3.5 to 2 nm results in a transition from continuous SiGe crystalline layer (tSiGe ~ 3...
June 19, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28610397/sliding-speed-dependent-tribochemical-wear-of-oxide-free-silicon
#5
Lei Chen, Yaqiong Qi, Bingjun Yu, Linmao Qian
Fundamental understanding of tribochemical wear mechanism of oxide-free single crystalline silicon (without native oxide layer) is essential to optimize the process of ultra-precision surface manufacturing. Here, we report sliding speed-dependent nanowear of oxide-free silicon against SiO2 microspheres in air and in deionized water. When contact pressure is too low to induce Si yield, tribochemical wear occurs with the existence of water molecules and wear volume decreases logarithmically to constant as sliding speed increased...
December 2017: Nanoscale Research Letters
https://www.readbyqxmd.com/read/28599097/in-plane-uniaxial-strain-in-black-phosphorus-enables-the-identification-of-crystalline-orientation
#6
Shuqing Zhang, Nannan Mao, Juanxia Wu, Lianming Tong, Jin Zhang, Zhirong Liu
Identification of the crystalline axis of anisotropic black phosphorus (BP) is important for investigating its physical properties, as well as for optical and electronic applications. Herein, it is showed that by applying in-plane uniaxial strain and measuring the changes of the Raman shifts, the crystalline axis of BP can be reliably determined. The strain effects on the Raman shifts are angle-dependent, and they can be expressed as a combination of the Raman responses under zigzag and armchair strain. Differing from previous polarized optical spectroscopic methods where the Raman intensity is analyzed, the proposed method uses the Raman frequency shift, which is less affected by laser polarization, excitation wavelength, the sample thickness, and the substrate...
June 9, 2017: Small
https://www.readbyqxmd.com/read/28587250/removal-of-carmine-from-aqueous-solution-by-carbonated-hydroxyapatite-nanorods
#7
Guanxiong Liu, Caibao Xue, Peizhi Zhu
In this study, carbonated hydroxyapatite (CHA) nanorods were prepared by a novel hydrothermal method. The crystallinity and chemical structure of synthesized CHA nanorods was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), respectively. Carmine was selected as representative organic dyes to study the adsorption capacities of CHA nanorods. Mechanistic studies of carmine adsorption by CHA nanorods show that the adsorption processes both follow the pseudo-second-order kinetic model and fit the Langmuir isotherm model well...
June 5, 2017: Nanomaterials
https://www.readbyqxmd.com/read/28581732/microwave-assisted-synthesis-of-perovskite-srsno3-nanocrystals-in-ionic-liquids-for-photocatalytic-applications
#8
Tarek Alammar, Ines Hamm, Viktoria Grasmik, Michael Wark, Anja-Verena Mudring
Nanosized SrSnO3 photocatalysts have been successfully synthesized by microwave synthesis in various ionic liquids (ILs) followed by a heat treatment process to optimize the materials' crystallinity. The influence of the ILs with various cations such as 1-butyl-3-methylimidazolium ([C4mim](+)), 6-bis(3-methylimidazolium-1-yl)hexane ([C6(mim)2](2+)), butylpyridinium ([C4Py](+)), and tetradecyltrihexylphosphonium ([P66614](+)) and bis(trifluoromethanesulfonyl)amide ([Tf2N](-)) as the anion on the structure, crystallization, and morphology of the products was investigated...
June 5, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28579458/cerium-oxide-nanoparticles-promote-hsa-fibrillation-in-vitro
#9
Gajalakshmi Sekar, N Prem Kumar, Amitava Mukherjee, Natarajan Chandrasekaran
Physicochemical characterization of CeO2NPs using UV-vis, FTIR and XRD have confirmed the characteristic identity and fluorite phase of their crystalline nature. The interaction studies between cerium oxide nanoparticles (CeO2NPs) and HSA were investigated using fluorescence emission and synchronous spectra, UV-vis absorbance, FTIR, FT-Raman and Circular Dichroism spectroscopy. Thermodynamic parameters and Stern-Volmer plot has conveyed the existence of the ground state complex raised due to static quenching...
June 1, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/28577510/drop-coating-deposition-raman-spectroscopy-of-proteinogenic-amino-acids-compared-with-their-solution-and-crystalline-state
#10
Tomáš Pazderka, Vladimír Kopecký
The Raman spectra of 20 proteinogenic amino acids were recorded in the solution, glass phase (as drop coating deposition Raman (DCDR) samples) and crystalline forms in the wide spectral range of 200-3200cm(-1). The most apparent spectral differences between the Raman spectra of the crystalline forms, glass phases and aqueous solutions of amino acids were briefly discussed and described in the frame of published works. The possible density dependencies of spectral bands were noted. In some cases, a strong influence of the sample density, as well as of the organization of the water envelope, was observed...
May 21, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28575978/fabrication-optimization-and-characterization-of-electrospun-poly-caprolactone-gelatin-graphene-nanofibrous-mats
#11
Mina Heidari, Hajir Bahrami, Marziyeh Ranjbar-Mohammadi
Recently graphene-based materials have been exploited widely in graphene-polymer nanocomposites and hold notable potential for various applications. In this study novel graphene-incorporated poly(caprolactone)/gelatin nanofibrous web were produced by electrospinning technique using acetic acid as a cost-effective eco-friendly solvent. Response surface methodology was used for optimizing the diameter of the electrospun nanofibrous web. To tailor electrospun nanofibers with suitable mechanical and electrical properties, the impact of affecting electrospinning parameters was studied...
September 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28575944/novel-and-facile-microwave-assisted-synthesis-of-mo-doped-hydroxyapatite-nanorods-characterization-gamma-absorption-coefficient-and-bioactivity
#12
M M Abutalib, I S Yahia
In the current work, the authors report the microwave-assisted synthesis Molybdenum-doped (from 0.05 to 5wt%) hydroxyapatite (HAp) for the first time. The morphology of Mo-doped HAp is nanorods of diameter in the range of 25-70nm and length in the range of 25nm to 200nm. The good crystalline nature was confirmed from X-ray diffraction patterns and also lattice parameters, grain size, strain and dislocation density were determined. The crystallite size was found to be in the range 16 to 30nm and crystallinity was found to be enhanced from 0...
September 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28575936/solid-crystal-suspension-of-efavirenz-using-hot-melt-extrusion-exploring-the-role-of-crystalline-polyols-in-improving-solubility-and-dissolution-rate
#13
Jaywant N Pawar, Ritesh A Fule, Mohammed Maniruzzaman, Purnima D Amin
Poor aqueous solubility of drugs has emerged as a major issue for pharmaceutical scientists from many decades. The current study explores the manufacture and development of a thermodynamically stabilized solid crystal suspension (SCS) of poorly water soluble drug efavirenz via hot melt extrusion. Efavirenz is a non-nucleoside reverse transcriptase inhibitor and belongs to BCS class II. The SCS was prepared using pearlitol and xylitol as a crystalline carrier. The drug-excipient blend was processed by hot melt extrusion with up to 50% (w/w) drug loading...
September 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/28575818/in-situ-studies-on-the-micro-structure-evolution-of-a2w2o7-a-li-na-k-during-melting-by-high-temperature-raman-spectroscopy-and-density-functional-theory
#14
Jian Wang, Jinglin You, Min Wang, Liming Lu, Songming Wan, A A Sobol
In-situ high temperature Raman spectroscopic (HTRS) technique in combination with density functional theory (DFT) analysis has been adopted to investigate the micro-structure of solid and molten A2W2O7 (A=Li, Na, K). The [WO6] octahedra were found to be connected to each other by corner and edge sharing in the crystalline Li2W2O7 and K2W2O7 compounds. In the crystal lattice of Na2W2O7, on the other hand, the [WO4] tetrahedra and [WO6] octahedra were found to coexist and paired by corner sharing. Although the structural diversity has clearly led to distinct Raman spectra of the crystalline A2W2O7 compounds, the spectra of their melts tended to be analogous, showing the typical vibration modes of (W2O7)(2-) dimer...
May 23, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28574714/fast-growth-of-gan-epilayers-via-laser-assisted-metal-organic-chemical-vapor-deposition-for-ultraviolet-photodetector-applications
#15
Hossein Rabiee Golgir, Da Wei Li, Kamran Keramatnejad, Qi Ming Zou, Jun Xiao, Fei Wang, Lan Jiang, Jean-François Silvain, Yong Feng Lu
In this study, we successfully developed a carbon dioxide (CO2)-laser-assisted metal-organic chemical vapor deposition (LMOCVD) approach to fast synthesis of high-quality gallium nitride (GaN) epilayers on Al2O3 [sapphire(0001)] substrates. By employing a two-step growth procedure, high crystallinity and smooth GaN epilayers with a fast growth rate of 25.8 μm/h were obtained. The high crystallinity was confirmed by a combination of techniques, including X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and atomic force microscopy...
June 13, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28574402/thermal-sublimation-a-scalable-and-controllable-thinning-method-for-the-fabrication-of-few-layer-black-phosphorus
#16
Weijun Luo, Rui Yang, Jialun Liu, Yunlong Zhao, Wenjuan Zhu, Guangrui Maggie Xia
We report uniform layer-by-layer sublimation of black phosphorus under heating below 600 K. The uniformity and crystallinity of BP samples after thermal thinning were confirmed by Raman spectra and Raman mapping. The sublimation rate of BP was around 0.18 nm min(-1) at 500 K and 1.15 nm min(-1) at 550 K. Both room and high temperature Raman peak intensity ratio [Formula: see text] as functions of BP thickness were established for in situ thickness determination and control. Uniform and crystalline 2 to 4-layer BP flakes with areas from 10 to 1000 μm(2) were prepared with this method...
June 2, 2017: Nanotechnology
https://www.readbyqxmd.com/read/28557413/manufacturing-te-pedot-films-for-thermoelectric-applications
#17
Mario Culebras, Ana María Igual-Muñoz, Carlos Rodríguez-Fernández, María Isabel Gómez-Gómez, Clara Gómez, Andrés Cantarero
In this work, flexible Te films have been synthesized by electrochemical deposition using PEDOT [poly(3,4-ethylenedioxythiophene)] nanofilms as working electrodes. The Te electrodeposition time was varied to find the best thermoelectric properties of the Te/PEDOT double layers. To show the high quality of the Te films grown on PEDOT, the samples were analyzed by Raman spectroscopy, showing the three Raman active modes of Te: E1, A1, and E2. The X-ray diffraction spectra also confirmed the presence of crystalline Te on top of the PEDOT films...
June 21, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28557169/delicate-changes-of-bioapatite-mineral-in-pig-femur-with-addition-of-dietary-xylooligosaccharide-evidences-from-raman-spectroscopy-and-icp
#18
Shujie Wang, Penghao Zhang, Xiangfeng Kong, Shengda Xie, Qiao Li, Zhen Li, Zhenlei Zhou
Bone mineral is strongly correlated with performance and health of animal bodies. The mineral bioapatite (BAp) is the dominant component in bone tissue. This study investigated mineralogical changes of BAp in pig femur by Raman spectroscopy and inductively coupled plasma optical emission spectrometry (ICP-OES). The pigs had been raised with various xylooligosaccharide (XOS) additions at two stages of growth (growing and fattening periods). The results show that XOS can decrease the degree of carbonate substitution for PO4 in BAp mineral and improve the mineral's crystallinity...
May 30, 2017: Animal Science Journal, Nihon Chikusan Gakkaihō
https://www.readbyqxmd.com/read/28554546/cyclodextrin-based-metal-organic-frameworks-particles-as-efficient-carriers-for-lansoprazole-study-of-morphology-and-chemical-composition-of-individual-particles
#19
Xue Li, Tao Guo, Laurent Lachmanski, Francesco Manoli, Mario Menendez-Miranda, Ilse Manet, Zhen Guo, Li Wu, Jiwen Zhang, Ruxandra Gref
Cyclodextrin-based metal-organic frameworks (CD-MOFs) represent an environment-friendly and biocompatible class of MOFs drawing increasing attention in drug delivery. Lansoprazole (LPZ) is a proton-pump inhibitor used to reduce the production of acid in the stomach and recently identified as an antitubercular prodrug. Herein, LPZ loaded CD-MOFs were successfully synthesized upon the assembly with γ-CD in the presence of K(+) ions using an optimized co-crystallization method. They were characterized in terms of morphology, size and crystallinity, showing almost perfect cubic morphologies with monodispersed size distributions...
May 26, 2017: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/28543094/mechanism-of-graphene-induced-cytotoxicity-role-of-endonucleases
#20
Tariq Fahmi, La Donna Branch, Zeid A Nima, Dae Song Jang, Alena V Savenka, Alexandru S Biris, Alexei G Basnakian
Graphene, a crystalline allotrope or carbon, presents numerous useful properties; however, its toxicity is yet to be determined. One of the most dramatic and irreversible toxic abilities of carbon nanomaterials is the induction of DNA fragmentation produced by endogenous cellular endonucleases. This study demonstrated that pristine graphene exposed to cultured kidney tubular epithelial cells is capable of inducing DNA fragmentation measured by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, which is usually associated with cell death...
May 24, 2017: Journal of Applied Toxicology: JAT
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