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Raman crystallinity

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https://www.readbyqxmd.com/read/27922033/profilometry-of-thin-films-on-rough-substrates-by-raman-spectroscopy
#1
Martin Ledinský, Bertrand Paviet-Salomon, Aliaksei Vetushka, Jonas Geissbühler, Andrea Tomasi, Matthieu Despeisse, Stefaan De Wolf, Christophe Ballif, Antonín Fejfar
Thin, light-absorbing films attenuate the Raman signal of underlying substrates. In this article, we exploit this phenomenon to develop a contactless thickness profiling method for thin films deposited on rough substrates. We demonstrate this technique by probing profiles of thin amorphous silicon stripes deposited on rough crystalline silicon surfaces, which is a structure exploited in high-efficiency silicon heterojunction solar cells. Our spatially-resolved Raman measurements enable the thickness mapping of amorphous silicon over the whole active area of test solar cells with very high precision; the thickness detection limit is well below 1 nm and the spatial resolution is down to 500 nm, limited only by the optical resolution...
December 6, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27921145/compressive-loading-of-the-murine-tibia-reveals-site-specific-micro-scale-differences-in-adaptation-and-maturation-rates-of-bone
#2
I Bergström, J G Kerns, A E Törnqvist, C Perdikouri, N Mathavan, A Koskela, H B Henriksson, J Tuukkanen, G Andersson, H Isaksson, A E Goodship, S H Windahl
: Loading increases bone mass and strength in a site-specific manner; however, possible effects of loading on bone matrix composition have not been evaluated. Site-specific structural and material properties of mouse bone were analyzed on the macro- and micro/molecular scale in the presence and absence of axial loading. The response of bone to load is heterogeneous, adapting at molecular, micro-, and macro-levels. INTRODUCTION: Osteoporosis is a degenerative disease resulting in reduced bone mineral density, structure, and strength...
December 5, 2016: Osteoporosis International
https://www.readbyqxmd.com/read/27916700/elucidation-and-visualization-of-solid-state-transformation-and-mixing-in-a-pharmaceutical-mini-hot-melt-extrusion-process-using-in-line-raman-spectroscopy
#3
Jeroen Van Renterghem, Ashish Kumar, Chris Vervaet, Jean Paul Remon, Ingmar Nopens, Yvan Vander Heyden, Thomas De Beer
Mixing of raw materials (drug+polymer) in the investigated mini pharma melt extruder is achieved by using co-rotating conical twin screws and an internal recirculation channel. In-line Raman spectroscopy was implemented in the barrels, allowing monitoring of the melt during processing. The aim of this study was twofold: to investigate (I) the influence of key process parameters (screw speed - barrel temperature) upon the product solid-state transformation during processing of a sustained release formulation in recirculation mode; (II) the influence of process parameters (screw speed - barrel temperature - recirculation time) upon mixing of a crystalline drug (tracer) in an amorphous polymer carrier by means of residence time distribution (RTD) measurements...
December 1, 2016: International Journal of Pharmaceutics
https://www.readbyqxmd.com/read/27914329/facile-synthesis-of-go-sno2-tio2-nanofibers-and-their-behavior-in-photovoltaics
#4
Ibrahim M A Mohamed, Van-Duong Dao, Ahmed S Yasin, Ho-Suk Choi, KhalilAbdelrazek Khalil, Nasser A M Barakat
Chemical doping is a widely-used strategy to improve the performance of TiO2 for the dye-sensitized solar cells (DSCs). However, the effect of two efficient dopants has been rarely investigated. We present the synthesis of GO@SnO2/TiO2 nanofibers (NFs) by a facile method using electrospinning and hydrothermal processes. The synthesized NFs are described in terms of morphology, crystallinity and chemistry through FESEM, TEM, HR-TEM, XRD, EDX, XPS, FT-IR and Raman spectra. As the results, the axial ratio and the average diameter of NFs decreased after the hydrothermal treatment and calcination process, respectively...
November 12, 2016: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/27910817/on-the-molecular-interaction-between-femoral-heads-and-polyethylene-liners-in-artificial-hip-joints-phenomenology-and-molecular-scale-phenomena
#5
Giuseppe Pezzotti, B Sonny Bal, Elisa Casagrande, Nobuhiko Sugano, Bryan J McEntire, Wenliang Zhu, Leonardo Puppulin
The chemical interaction of femoral heads with polyethylene liners is an important new area of research in total hip arthroplasty (THA) as a consequence of an unabating quest for elongated artificial joint lifetimes. It is a topic that goes beyond simple mechanical behavior or wear. It seeks to describe the prosthetic device as a whole by adding chemical considerations to mechanics and abrasion. One of the poorly understood chemical interactions is oxygen affinity of the femoral heads. While oxygen unavoidably diffuses into the non-crystalline enclaves of the polyethylene liner as a result of its contact with the tribolayer, a ceramic femoral head can either attract or release oxygen due to its tribochemical interactions...
December 2, 2016: Biomedical Materials
https://www.readbyqxmd.com/read/27906391/large-area-growth-of-vertically-aligned-luminescent-mos2-nanosheets
#6
G Deokar, N S Rajput, P Vancsó, F Ravaux, M Jouiad, D Vignaud, F Cecchet, J-F Colomer
Vertically aligned MoS2 nanosheets (NSs) with exposed edges were successfully synthesized over a large area (∼2 cm(2)). The NSs were grown using an ambient pressure chemical vapor deposition technique via rapid sulfurization of sputter deposited thick molybdenum films. Extensive characterization of the grown MoS2 NSs has been carried out using high resolution scanning and transmission electron microscopy (SEM & TEM). A special care was given to the TEM lamella preparation process by means of a focused ion beam to preserve the NS growth direction...
December 1, 2016: Nanoscale
https://www.readbyqxmd.com/read/27895234/ultraviolet-raman-wide-field-hyperspectral-imaging-spectrometer-for-standoff-trace-explosive-detection
#7
Kyle T Hufziger, Sergei V Bykov, Sanford A Asher
We constructed the first deep ultraviolet (UV) Raman standoff wide-field imaging spectrometer. Our novel deep UV imaging spectrometer utilizes a photonic crystal to select Raman spectral regions for detection. The photonic crystal is composed of highly charged, monodisperse 35.5 ± 2.9 nm silica nanoparticles that self-assemble in solution to produce a face centered cubic crystalline colloidal array that Bragg diffracts a narrow ∼1.0 nm full width at half-maximum (FWHM) UV spectral region. We utilize this photonic crystal to select and image two different spectral regions containing resonance Raman bands of pentaerythritol tetranitrate (PETN) and NH4NO3 (AN)...
November 28, 2016: Applied Spectroscopy
https://www.readbyqxmd.com/read/27892655/3d-printed-polycaprolactone-carbon-nanotube-composite-scaffolds-for-cardiac-tissue-engineering
#8
Chee Meng Benjamin Ho, Abhinay Mishra, Pearlyn Teo Pei Lin, Sum Huan Ng, Wai Yee Yeong, Young-Jin Kim, Yong-Jin Yoon
Fabrication of tissue engineering scaffolds with the use of novel 3D printing has gained lot of attention, however systematic investigation of biomaterials for 3D printing have not been widely explored. In this report, well-defined structures of polycaprolactone (PCL) and PCL- carbon nanotube (PCL-CNT) composite scaffolds have been designed and fabricated using a 3D printer. Conditions for 3D printing has been optimized while the effects of varying CNT percentages with PCL matrix on the thermal, mechanical and biological properties of the printed scaffolds are studied...
November 28, 2016: Macromolecular Bioscience
https://www.readbyqxmd.com/read/27892489/laser-light-induced-transformation-of-molybdenum-disulphide-based-nanoplatelet-arrays
#9
Arūnas Jagminas, Gediminas Niaura, Rokas Žalnėravičius, Romualdas Trusovas, Gediminas Račiukaitis, Vitalija Jasulaitiene
One-pot hydrothermal synthesis of MoS2 nanoplatelet arrays on various substrates is perhaps the most promising approach to fabricate efficient electrocatalysts for hydrogen evolution reaction. However, the main challenges in this synthesis remain the purity and crystallinity of MoS2. In this study, we show for the first time that irradiation of amorphous, defect-rich MoS2 nanoplatelets with a green nanosecond laser at a proper irradiation dose, ca ≤0.35 J cm(-2), can significantly improve the crystallinity and purity of MoS2 nanoplatelets...
November 28, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27889181/brazilian-cerrado-soil-reveals-an-untapped-microbial-potential-for-unpretreated-polyethylene-biodegradation
#10
Julianna Peixoto, Luciano P Silva, Ricardo H Krüger
Discarded PE-based products pose a social and environmental threat because of their recalcitrance to degradation, a consequence of the unique set of PE's physicochemical properties. In this study we isolated nine novel PE-degrading bacteria from plastic debris found in soil of the savanna-like Brazilian Cerrado. These bacterial strains from the genera Comamonas, Delftia, and Stenotrophomonas showed metabolic activity and cellular viability after a 90-day incubation with PE as the sole carbon source. ATR/FTIR indicated that biodegraded PE undergone oxidation, vinylene formation, chain scission, among other chemical changes...
November 14, 2016: Journal of Hazardous Materials
https://www.readbyqxmd.com/read/27886647/high-pressure-raman-scattering-study-on-sm2mo4o15-system
#11
S D Silva Santos, W Paraguassu, M Maczka, P T C Freire
High-pressure Raman experiments were performed on Sm2Mo4O15 system up to 7.9GPa. We show that this system exhibits an irreversible structural amorphization at 5.0GPa. In contrast to any other molybdates and tungstates experiencing pressure-induced amorphization, this structural change in Sm2Mo4O15 has strongly first-order character. This amorphous phase can be originated from the hindrance of a crystalline structural phase transition from the P1¯ to P2/m structure. Additionally, the assignment of Raman modes of the ambient-pressure phase of Sm2Mo4O15 was proposed based on lattice dynamics calculations...
November 19, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/27882619/in-operando-mechanism-analysis-on-nanocrystalline-silicon-anode-material-for-reversible-and-ultrafast-sodium-storage
#12
Lei Zhang, Xianluo Hu, Chaoji Chen, Haipeng Guo, Xiaoxiao Liu, Gengzhao Xu, Haijian Zhong, Shuang Cheng, Peng Wu, Jiashen Meng, Yunhui Huang, Shixue Dou, Huakun Liu
The electrochemical mechanism of nanocrystalline silicon anode in sodium ion batteries is first studied via in operando Raman and in operando X-ray diffraction. An irreversible structural conversion from crystalline silicon to amorphous silicon takes place during the initial cycles, leading to ultrafast reversible sodium insertion in the newly generated amorphous silicon. Furthermore, an optimized silicon/carbon composite has been developed to further improve its electrochemical performance.
November 24, 2016: Advanced Materials
https://www.readbyqxmd.com/read/27873767/high-pressure-studies-with-x-rays-using-diamond-anvil-cells
#13
Guoyin Shen, Ho Kwang Mao
Pressure profoundly alters all states of matter. The symbiotic development of ultrahigh-pressure diamond anvil cells, to compress samples to sustainable multi-megabar pressures; and synchrotron x-ray techniques, to probe materials' properties in situ, has enabled the exploration of rich high-pressure (HP) science. In this article, we first introduce the essential concept of diamond anvil cell technology, together with recent developments and its integration with other extreme environments. We then provide an overview of the latest developments in HP synchrotron techniques, their applications, and current problems, followed by a discussion of HP scientific studies using x-rays in the key multidisciplinary fields...
November 22, 2016: Reports on Progress in Physics
https://www.readbyqxmd.com/read/27859586/lactation-induced-changes-in-the-volume-of-osteocyte-lacunar-canalicular-space-alter-mechanical-properties-in-cortical-bone-tissue
#14
Serra Kaya, Jelena Basta-Pljakic, Zeynep Seref-Ferlengez, Robert J Majeska, Luis Cardoso, Timothy Bromage, Qihong Zhang, Carol R Flach, Richard Mendelsohn, Shoshana Yakar, Susannah P Fritton, Mitchell B Schaffler
Osteocytes can remove and remodel small amounts of their surrounding bone matrix through osteocytic osteolysis, which results in increased volume occupied by lacunar and canalicular space (LCS). It is well established that cortical bone stiffness and strength are strongly and inversely correlated with vascular porosity, but whether changes in LCS volume caused by osteocytic osteolysis are large enough to affect bone mechanical properties is not known. In the current studies we tested the hypotheses that i) lactation and post-lactation recovery in mice alter the elastic modulus of bone tissue, and ii) such local changes in mechanical properties are related predominantly to alterations in lacunar and canalicular volume rather than bone matrix composition...
November 18, 2016: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
https://www.readbyqxmd.com/read/27826025/vitamin-d-and-calcium-supplementation-for-three-years-in-postmenopausal-osteoporosis-significantly-alters-bone-mineral-and-organic-matrix-quality
#15
E P Paschalis, S Gamsjaeger, N Hassler, A Fahrleitner-Pammer, H Dobnig, J J Stepan, I Pavo, E F Eriksen, K Klaushofer
Prospective, controlled clinical trials in postmenopausal osteoporosis typically compare effects of an active drug with placebo in addition to vitamin D and calcium supplementation in both treatment arms. While clinical benefits are documented, the effect of this supplementation in the placebo arm and in clinical practice on bone material composition properties is unknown. The purpose of the present study was to evaluate these bone quality indices (specifically mineral/matrix, nanoporosity, glycosaminoglycan content, mineral maturity/crystallinity, and pyridinoline content) in patients that either received long-term vitamin D (400-1200IU) and calcium (1...
November 5, 2016: Bone
https://www.readbyqxmd.com/read/27826024/ovarian-hormone-depletion-affects-cortical-bone-quality-differently-on-different-skeletal-envelopes
#16
E P Paschalis, S Gamsjaeger, N Hassler, K Klaushofer, D Burr
The physical properties of bone tissue are determined by the organic and mineral matrix, and are one aspect of bone quality. As such, the properties of mineral and matrix are a major contributor to bone strength, independent of bone mass. Cortical bone quality may differ regionally on the three skeletal envelopes that compose it. Each of these envelopes may be affected differently by ovarian hormone depletion. Identifying how these regions vary in their tissue adaptive response to ovarian hormones can inform our understanding of how tissue quality contributes to overall bone strength in postmenopausal women...
November 4, 2016: Bone
https://www.readbyqxmd.com/read/27825283/physical-chemical-properties-of-furosemide-nanocrystals-developed-using-rotation-revolution-mixer
#17
Sávio Fujita Barbosa, Takayuki Takatsuka, Guilherme Diniz Tavares, Gabriel Lima Barros Araújo, Hui Wang, Reinhard Vehring, Raimar Löbenberg, Nádia Araci Bou-Chacra
Recently, several approaches have been reported to improve the dissolution rate and bioavailability of furosemide, a class IV drug. However, to the best of our knowledge, none of them proposed nanocrystals. In the last decade, nanocrystals successfully addressed solubility issues by increasing surface area and saturation solubility, both leading to an increase in the dissolution rate of poor water soluble drugs. The preparation of furosemide nanocrystals was by a rotation revolution mixer method. Size distribution and morphology were performed using laser diffraction and scanning electron microscopy, respectively...
November 2016: Pharmaceutical Development and Technology
https://www.readbyqxmd.com/read/27819265/new-porous-water-ice-metastable-at-atmospheric-pressure-obtained-by-emptying-a-hydrogen-filled-ice
#18
Leonardo Del Rosso, Milva Celli, Lorenzo Ulivi
The properties of some forms of water ice reserve still intriguing surprises. Besides the several stable or metastable phases of pure ice, solid mixtures of water with gases are precursors of other ices, as in some cases they may be emptied, leaving a metastable hydrogen-bound water structure. We present here the first characterization of a new form of ice, obtained from the crystalline solid compound of water and molecular hydrogen called C0-structure filled ice. By means of Raman spectroscopy, we measure the hydrogen release at different temperatures and succeed in rapidly removing all the hydrogen molecules, obtaining a new form of ice (ice XVII)...
November 7, 2016: Nature Communications
https://www.readbyqxmd.com/read/27802720/the-rheo-raman-microscope-simultaneous-chemical-conformational-mechanical-and-microstructural-measures-of-soft-materials
#19
Anthony P Kotula, Matthew W Meyer, Francesca De Vito, Jan Plog, Angela R Hight Walker, Kalman B Migler
The design and performance of an instrument capable of simultaneous Raman spectroscopy, rheology, and optical microscopy are described. The instrument couples a Raman spectrometer and optical microscope to a rotational rheometer through an optically transparent base, and the resulting simultaneous measurements are particularly advantageous in situations where flow properties vary due to either chemical or conformational changes in molecular structure, such as in crystallization, melting, gelation, or curing processes...
October 2016: Review of Scientific Instruments
https://www.readbyqxmd.com/read/27802654/pressure-induced-polymerization-of-fluid-ethylene
#20
Demetrio Scelta, Matteo Ceppatelli, Roberto Bini
The spontaneous polymerization of fluid ethylene under high temperature and pressure conditions has been characterized by using FTIR absorption spectroscopy. The fluid has been isobarically heated at pressures ranging between 0.4 and 1.5 GPa by means of a resistively heated membrane diamond anvil cell. Besides tracing the instability boundary for spontaneous polymerization in the fluid, we have also measured the reaction kinetics at 1.5 GPa and temperatures ranging between 340 and 423 K. From the rate constants the activation energy of the overall reaction could be computed, information that joined to the molecularity of the initiation step provides some insight about the reaction mechanism...
October 28, 2016: Journal of Chemical Physics
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