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Raman crystallinity

Seung Min Lee, Jung Hwan Yum, Seonno Yoon, Eric S Larsen, Woo Chul Lee, Seong Keun Kim, Shahab Shervin, Weijie Wang, Jae-Hyun Ryou, Christopher W Bielawski, Jungwoo Oh
We have developed a beryllium oxide (BeO) thin film process by atomic layer deposition (ALD) and grown a single-crystal BeO on a gallium nitride (GaN) substrate for the first time. BeO has a higher thermal conductivity than all other metals except Cu, Ag, and Au, and it has a higher bandgap energy and dielectric constant than SiO2 and Al2O3. As an electrical insulator, diamond is the only material on Earth whose thermal conductivity exceeds that of BeO. Despite these advantages, there is no chemical vapor deposition technique for BeO thin film deposition, and thus, it is not used in nanoscale semiconductor device processing...
November 17, 2017: ACS Applied Materials & Interfaces
Yongcheng Li, Ming Lu, Chuanbin Wu
The purpose of this study was to explore poly(vinylpyrrolidone-co-vinyl acetate) (PVP VA64) as a novel release-modifier to tailor the drug release from ethylcellulose (EC)-based mini-matrices prepared via hot melt extrusion (HME). Quetiapine fumarate (QF) was selected as model drug. QF/EC/PVP VA64 mini-matrices were extruded with 30% drug loading. The physical state of QF in extruded mini-matrices was characterized using differential scanning calorimetry, X-ray powder diffraction, and confocal Raman microscopy...
November 10, 2017: Drug Delivery and Translational Research
Nestor J Bello-Vieda, Ricardo A Murcia, Alvaro Muñoz-Castro, Mario A Macías, John J Hurtado
The reaction of isophthaloyl dichloride with 1H-1,2,4-triazole afforded the new ligand 1,3-phenylenebis(1,2,4-triazole-1-yl)methanone (1). A series of Co(II), Cu(II), Zn(II) and Ni(II) complexes were synthesized using 1 and then characterized by melting point analysis, elemental analysis, theoretical calculations, thermogravimetric analysis, X-ray powder diffraction, nuclear magnetic resonance, infrared and Raman spectroscopy. Experimental and computational studies predict the formation of coordination polymers (CPs)...
November 10, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Sudip Nag, Arnab Pramanik, Dhrubajyoti Chattopadhyay, Maitree Bhattacharyya
Microbial synthesis of gold nanoparticles (GNPs) has attracted considerable attention in recent times due to their exceptional capability for the bioremediation of industrial wastes and also for the treatment of wastewater. A bacterial strain Staphylococcus warneri, isolated from the estuarine mangroves of Sundarbans region produced highly stable GNPs by reducing hydrogen auric chloride (HAucl4) salt using intracellular protein extract. The nanoparticles were characterized utilizing ultraviolet-visible spectrophotometry, transmission electron microscopy, scanning electron microscopy, atomic force microscopy, X-ray diffraction, and surface enhanced Raman scattering...
November 9, 2017: Environmental Science and Pollution Research International
Naveen K Kalagatur, Kumarvel Karthick, Joseph A Allen, Oriparambil Sivaraman Nirmal Ghosh, Siddaiah Chandranayaka, Vijai K Gupta, Kadirvelu Krishna, Venkataramana Mudili
In the present study, activated carbon (AC) was derived from seed shells of Jatropha curcas and applied to decontaminate the zearalenone (ZEA) mycotoxin. The AC of J. curcas (ACJC) was prepared by ZnCl2 chemical activation method and its crystalline structure was determined by X-ray diffraction analysis. The crystalline graphitic nature of ACJC was confirmed from the Raman spectroscopy. Scanning electron microscope showed the porous surface morphology of the ACJC surface with high pore density and presence of elemental carbon was identified from the energy dispersive X-ray analysis...
2017: Frontiers in Pharmacology
Frank Theil, Johanna Milsmann, Samuel O Kyeremateng, Sankaran Anantharaman, Jörg Rosenberg, Holger van Lishaut
Inhibition of recrystallization of the drug substance in kinetically stabilized amorphous solid dispersions (ASDs) within and beyond shelf life is still a matter of debate. Generally, these ASD systems are considered to be prone to recrystallization, but examples of their long term stability are emerging in the literature. Since, in some cases, the formation of crystals may impact bioavailability, recrystallization may present a relevant risk for patients as it potentially lowers the effective dose of the formulation...
November 7, 2017: Molecular Pharmaceutics
Samuel Tardif, Ekaterina Pavlenko, Lucille Quazuguel, Maxime Boniface, Manuel Maréchal, Jean-Sébastien Micha, Laurent Gonon, Vincent Mareau, Gérard Gebel, Pascale Bayle-Guillemaud, François Rieutord, Sandrine Lyonnard
Operando Raman spectroscopy and synchrotron X-ray diffraction were combined to probe the evolution of strain in Li-ion battery anodes made of crystalline silicon nanoparticles. The internal structure of the nanoparticles during two discharge/charge cycles was evaluated by analyzing the intensity and position of Si diffraction peaks and Raman TO-LO phonons. Lithiation/delithiation of the silicon under limited capacity conditions triggers the formation of "crystalline core-amorphous shell" particles, which we evidenced as a stepwise decrease in core size, as well as sequences of compressive/tensile strain due to the stress applied by the shell...
November 9, 2017: ACS Nano
Taehong Gwon, Ahmed Mohamed, Chanyoung Yoo, Eui-Sang Park, Sanggyun Kim, Sijung Yoo, Han-Koo Lee, Deok-Yong Cho, Cheol Seong Hwang
The local bonding structures of GexTe1-x (x=0.5, 0.6, and 0.7) films prepared through atomic layer deposition (ALD) with Ge(N(Si(CH3)3)2)2 and ((CH3)3Si)2Te precursors were investigated using Ge K-edge X-ray absorption spectroscopy (XAS). The results of the X-ray absorption fine structure analyses show that for all the compositions, the as-grown films were amorphous with a tetrahedral Ge coordination of a mixture of Ge-Te and Ge-Ge bonds, but without any signature of Ge-GeTe decomposition. The compositional evolution in the valence band electronic structures probed through X-ray photoelectron spectroscopy suggests a substantial chemical influence of additional Ge on the nonstoichiometric GeTe...
November 7, 2017: ACS Applied Materials & Interfaces
X Ojanen, P Tanska, M K H Malo, H Isaksson, S P Väänänen, A P Koistinen, L Grassi, S P Magnusson, S M Ribel-Madsen, R K Korhonen, J S Jurvelin, J Töyräs
Trabecular bone is viscoelastic under dynamic loading. However, it is unclear how tissue viscoelasticity controls viscoelasticity at the apparent-level. In this study, viscoelasticity of cylindrical human trabecular bone samples (n=11, male, age 18-78 years) from 11 proximal femurs were characterized using dynamic and stress-relaxation testing at the apparent-level and with creep nanoindentation at the tissue-level. In addition, bone tissue elasticity was determined using scanning acoustic microscope (SAM)...
October 13, 2017: Journal of Biomechanics
Katarzyna Gniado, Pól MacFhionnghaile, Patrick McArdle, Andrea Erxleben
The amorphization of 18 different drugs on milling with one mole equivalent sodium taurocholate (NaTC) was investigated. In all cases the X-ray powder pattern showed an amorphous halo after milling at room temperature or after cryomilling and 14 of the 18 coamorphous drug-NaTC systems were physically stable for between one to eleven months under ambient storage conditions. In three cases, namely carbamazepine-NaTC, indomethacin-NaTC and mefenamic acid-NaTC, significant dissolution advantages over the crystalline drugs were observed, both for the freshly prepared samples and after storage for seven months...
October 28, 2017: International Journal of Pharmaceutics
Thokchom Taru Taru Chanu, N Rajmuhon Singh
A series of monophasic Tb(3+) (2, 5, 7, 10 and 15at%) doped PbWO4 phosphors were successfully prepared via hydrothermal method. X-ray diffraction patterns revealed that the prepared samples possess a high crystallinity with tetragonal scheelite-type structure. FT-IR and Raman analysis exhibited a WO stretching peak of WO4(2-) group, which is also related to the scheelite structure. UV-visible diffuse reflectance spectra indicated a reduction in the optical band gap with the replacement of Pb(2+) by Tb(3+) ions...
October 26, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Dip K Nandi, Sumanta Sahoo, Soumyadeep Sinha, Seungmin Yeo, Hyungjun Kim, Ravindra N Bulakhe, Jaeyeong Heo, Jae-Jin Shim, Soo-Hyun Kim
This article takes an effort to establish the potential of atomic layer deposition (ALD) technique toward the field of supercapacitors by preparing molybdenum disulfide (MoS2) as its electrode. While molybdenum hexacarbonyl [Mo(CO)6] serves as a novel precursor toward the low-temperature synthesis of ALD-grown MoS2, H2S plasma helps to deposit its polycrystalline phase at 200 °C. Several ex situ characterizations such as X-ray diffractometry (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and so forth are performed in detail to study the as-grown MoS2 film on a Si/SiO2 substrate...
November 13, 2017: ACS Applied Materials & Interfaces
Adrian Paz Ramos, Gert Gooris, Joke Bouwstra, Michel Lafleur
The stratum corneum (SC), the top layer of skin, dictates both the rate of water loss through the skin, and absorption of exogenous molecules into the body. The crystalline organization of the lipids in the SC is believed to be a key feature associated with the very limited permeability of the skin. In this work, we characterized the organization of SC lipid models that include, as in native SC, cholesterol, a free fatty acid series (saturated with C16-C24 chains), as well as a ceramide bearing an oleate linked to a very long saturated acyl chain (Cer EOS)...
November 1, 2017: Journal of Lipid Research
Greg Walker, Philipp Römann, Bettina Poller, Korbinian Löbmann, Holger Grohganz, Jeremy S Rooney, Gregory S Huff, Geoffrey P S Smith, Thomas Rades, Keith C Gordon, Clare J Strachan, Sara J Fraser-Miller
This study uses a multimodal analytical approach to evaluate the rates of (co)amorphization of milled drug and excipient and the effectiveness of different analytical methods in detecting these changes. Indomethacin and tryptophan were the model substances, and the analytical methods included low-frequency Raman spectroscopy (785 nm excitation and capable of measuring both low- (10 to 250 cm(-1)) and midfrequency (450 to 1800 cm(-1)) regimes, and a 830 nm system (5 to 250 cm(-1))), conventional (200-3000 cm(-1)) Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRPD)...
November 16, 2017: Molecular Pharmaceutics
Lina Kong, Changhua Wang, Fangxu Wan, Lan Li, Xintong Zhang, Yichun Liu
Doping and tailoring of the crystal orientation are two main strategies to improve the photocatalytic properties of TiO2 films. Herein, we introduce a novel route for obtaining Nb-doped TiO2 anatase films with the [001] preferred orientation by thermal oxidation of the [100]-oriented Nb-doped TiN film prepared by magnetron sputtering. Comprehensive analyses with X-ray diffraction, Raman scattering, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy indicate that the proportion of high-energy (001) facets of the Nb-doped TiO2 film is more than 90% and the Nb(5+) ion is successfully doped into the film without destroying the crystallinity and orientation...
November 14, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Bohr-Ran Huang, Jinn P Chu, Cheng-Liang Hsu, You-Syuan Chen, Chia-Hao Chang
A few layers of Cu-based (Cu47Zr42Al7Ti4) thin-film metallic glasses (TFMGs) were sputtered on hydrothermally synthesized ZnO nanowires/glass and ZnO nanotubes/glass to fabricate UV photodetectors. The few layers of Cu-based TFMG are ultrathin at ∼0.98 nm and have a noncrystalline metal structure according to X-ray diffraction, Raman, photoluminescence, and high-temperature transmission electron microscopy verification. The photoresponse performance of the coated few-layers Cu-TFMG samples was enhanced 1680-7700% compared with the noncoated sample...
November 1, 2017: ACS Applied Materials & Interfaces
Sebastian Haferkamp, Franziska Fischer, Werner Kraus, Franziska Emmerling
The mechanochemical Knoevenagel condensation of malononitrile with p-nitrobenzaldehyde was studied in situ using a tandem approach. X-ray diffraction and Raman spectroscopy were combined to yield time-resolved information on the milling process. Under solvent-free conditions, the reaction leads to a quantitative conversion to p-nitrobenzylidenemalononitrile within 50 minutes. The in situ data indicate that the process is fast and proceeds under a direct conversion. After stopping the milling process, the reaction continues until complete conversion...
2017: Beilstein Journal of Organic Chemistry
Haoming Bao, Hongwen Zhang, Le Zhou, Guangqiang Liu, Yue Li, Weiping Cai
Controllable and flexible fabrication of ultrathin and uniform oxide layer-wrapped noble metal nanoparticles (NPs) has been expected. Here a new strategy is presented for them based on colloidal electrostatic attraction and self-assembly on the metal NPs via one-step laser ablation of noble metal targets in the hydrolysis-induced hydroxide sol solutions at room temperature. The Au NPs, with several tens of nanometers in size, are taken as core part and TiO2 as shell-layer to demonstrate the validity of the presented strategy...
November 2, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Aiden A Martin, Jorge Filevich, Marcus Straw, Steven Randolph, Aurélien Botman, Igor Aharonovich, Milos Toth
Ultra-nanocrystalline diamond (UNCD) is increasingly being used in the fabrication of devices and coatings due to its excellent tribological properties, corrosion resistance, and biocompatibility. Here, we study its response to irradiation with kiloelectronvolt electrons as a controlled model for extreme ionizing environments. Real time Raman spectroscopy reveals that the radiation-damage mechanism entails dehydrogenation of UNCD grain boundaries, and we show that the damage can be recovered by annealing at 883 K...
October 31, 2017: ACS Applied Materials & Interfaces
Kezia Sasitharan, Anitha Varghese, Louis George
A highly selective novel fluorescent probe was prepared by using surface modified ZnS:Mn nanoparticles, functionalized with morin, a flavonol. SEM investigations of the heterostructures prepared using wet chemical precipitation technique revealed a nanoflake type of morphology. HR-TEM and powder XRD analysis confirmed the crystalline planes corresponding to Wurtzite ZnS. The functionalized nanoparticles were characterized using Raman, XPS and FTIR which confirms the binding of morin to the nanoparticles via surface coordination...
November 1, 2017: Analytica Chimica Acta
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