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Raman crystallinity

Iwona Koltsov, Julita Smalc-Koziorowska, Marta Prześniak-Welenc, Maria Małysa, Giora Kimmel, Jessica McGlynn, Alexey Ganin, Swietlana Stelmakh
A novel method to obtain Al₂O₃⁻ZrO₂ nanocomposites is presented. It consists of the co-precipitation step of boehmite (AlO(OH)) and ZrO₂, followed by microwave hydrothermal treatment at 270 °C and 60 MPa, and by calcination at 600 °C. Using this method, we obtained two nanocomposites: Al₂O₃⁻20 wt % ZrO₂ and Al₂O₃⁻40 wt % ZrO₂. Nanocomposites were characterized by Fourier transformed infrared spectroscopy, Raman spectroscopy, X-ray diffraction, and transmission electron microscopy...
May 17, 2018: Materials
Venkata Raman Kallakunta, Roshan Tiwari, Sandeep Sarabu, Suresh Bandari, Michael A Repka
The current study's aim is to prepare lipid based sustained release tablets via a twin-screw granulation technique and compare those dosage forms with conventional techniques, namely wet granulation and direct compression. The granules were successfully manufactured in a single-step, continuous twin-screw granulation process with a low proportion of binder (Klucel™ EF, HPC SSL) using Compritol® 888 ATO, Precirol® ATO 5 and Geleol™ as sustained release agents. The granules prepared showed good flow characteristics and compaction properties...
May 14, 2018: European Journal of Pharmaceutical Sciences
M Ramachandran, R Subadevi, Wei-Ren Liu, M Sivakumar
The crystalline Zirconium oxide (ZrO2) nano particles were synthesized using optimized content of Zirconium nitrate (Zr(NO3)2·3H2O) with varying KOH concentration (0.5, 1 and 1.5 M) by co-precipitation method. The thermal history of the precursor was carefully analyzed through Thermogravimetric (TG/DTA) measurement. The as prepared samples were characterized to ensure structural, functional, morphological, compositional, chemical composition and band gap by X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), Laser Raman, scanning electron microscopy (SEM), High resolution Transverse Electron Microscopy (HR-TEM), X-ray photo electron spectroscopy (XPS), EDX, Photo luminescence spectroscopy (PL)...
January 1, 2018: Journal of Nanoscience and Nanotechnology
R Muthupradeepa, M Sivakumar, R Subadevi, V Suryanarayanan, Wei-Ren Liu
The present study emphases on the effect of toting of TiO2 filler on the electrochemical enactment of polymer electrolyte containing PVdF-co-HFP(30) + SEt3TFSI(10) + EC/PC(60) + TiO2(x) wt% (Poly (vinylidene fluoride-co-hexafluoropropylene + Triethylsulfoniumbis(trifluoromethylsulfonyl)imide + Ethylene carbonate/Propylene carbonate (1:1 ratio) + Titanium dioxide) for lithium battery applications. Composite electrolytes with different weight percentages of TiO2 were prepared and characterized by different surface analytical, thermal and electrochemical techniques...
January 1, 2018: Journal of Nanoscience and Nanotechnology
Diane M Haiber, Peter A Crozier
In graphitic carbon nitrides, (photo)catalytic functionality is underpinned by the effect that residual hydrogen content, manifesting in amine (N-Hx ) defects, has on its optoelectronic properties. Therefore, a detailed understanding of the variation in the local structure of graphitic carbon nitrides is key for understanding structure-activity relationships. Here we apply aloof-beam vibrational electron energy-loss spectroscopy in the scanning transmission electron microscope (STEM) to locally detect variations in hydrogen content in two different layered carbon nitrides with nanometer resolution...
May 16, 2018: ACS Nano
E Mitsai, A Kuchmizhak, E Pustovalov, A Sergeev, A Mironenko, S Bratskaya, D P Linklater, A Balčytis, E Ivanova, S Juodkazis
All-dielectric resonant micro- and nano-structures made of high-index dielectrics have recently emerged as a promising surface-enhanced Raman scattering (SERS) platform which can complement or potentially replace the metal-based counterparts in routine sensing measurements. These unique structures combine the highly-tunable optical response and high field enhancement with the non-invasiveness, i.e. chemically non-perturbing the analyte, simple chemical modification and recyclability. Meanwhile, commercially competitive fabrication technologies for mass production of such structures are still missing...
May 16, 2018: Nanoscale
Wioleta Edyta Śmiszek-Lindert, Elżbieta Chełmecka, Olaf Lindert, Anna Dudzińska, Ilona Kaczmarczyk-Sedlak
This paper presents the investigation results of the polarized IR spectra of the hydrogen bond in crystals of N-acetylbenzylamine and its sulphur analogue N-benzyl-ethanethioamide. The spectra were measured at 298 and 77 K by a transmission method, with the use of polarized light. The Raman spectroscopy, Hirshfeld surfaces analysis and DFT studies have been also reported. Theoretical calculations of the isolated molecule were performed by using density functional theory (DFT) method at B3LYP/6-311(d,p), B3LYP/6-311++G(d,p) and B3LYP/6-311++G(3df,2pd) basis set levels...
May 8, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Prokhor A Alekseev, Mikhail S Dunaevskiy, George E Cirlin, Rodion Reznik, Alexander Smirnov, Demid Kirilenko, Valery Davydov, Vladimir L Berkovits
Fermi level pinning at the oxidized (110) surfaces of III-As nanowires (GaAs, InAs, InGaAs, AlGaAs) is studied. Using scanning gradient Kelvin probe microscopy, we show that the Fermi level at oxidized cleavage surfaces of ternary Al<sub>x</sub>Ga<sub>1-x</sub>As (0≤x≤0.45) and Ga<sub>x</sub>In<sub>1-x</sub>As (0≤x≤1) alloys is pinned at the same position of 4.8 ± 0.1 eV with regard to the vacuum level...
May 14, 2018: Nanotechnology
Nizar Al-Zoubi, Faten Odah, Wasfy Obeidat, Ahmad Al-Jaberi, Ioannis Partheniadis, Ioannis Nikolakakis
Solid dispersions of spironolactone with Soluplus® and PVP were prepared by spray drying according to a mixture experimental design and evaluated for moisture content, particle size, drug solubility, crystallinity (PXRD and DSC) and physicochemical interactions (FTIR, Raman). In vitro dissolution was evaluated for the spray dried product itself and after compression into tablets and prediction models were derived using multiple linear regression analysis. The spray dried products consisted of amorphous drug, indicated by the absence of crystalline PXRD peaks...
May 9, 2018: Journal of Pharmaceutical Sciences
Xin Sun, Zonghuan Lu, Yu Xiang, Yiping Wang, Jian Shi, Gwo-Ching Wang, Morris A Washington, Toh-Ming Lu
Antimony (Sb) nanostructures, including islands, sheets, and thin films, of high crystallinity were epitaxially grown on single-crystalline graphene through van der Waals interactions. Two types of graphene substrates grown by chemical vapor deposition (CVD) were used, the as-grown graphene on Cu(111)/c-sapphire and the transferred graphene on SiO2/Si. On the as-grown graphene, deposition of ultrathin Sb resulted in two growth modes and associated morphologies of Sb. One was Sb islands grown in Volmer-Weber (VW) mode and the other was Sb sheets grown in Frank-van der Merve (FM) mode...
May 10, 2018: ACS Nano
Xingzhi Wang, Nannan Mao, Weijun Luo, Hikari Kitadai, Xi Ling
Black phosphorus (BP), a layered material with puckered crystalline structure in each layer, drew intense interest due to its unique optical and electronic properties. In particular, the intricate Raman scattering effect in BP is intriguing and provides a platform for researchers to probe the physical properties of BP in depth. Here we report the first observation of anomalous modes with the frequency in the range of 100-900 cm-1 in BP due to the resonant Raman effect. The origin and assignment of the anomalous modes are discussed based on the excitation energy and angle-dependent Raman measurements...
May 10, 2018: Journal of Physical Chemistry Letters
José-Luis Ortiz-Quiñonez, Umapada Pal, Martin Salazar Villanueva
Fabrication of phase-pure well-crystalline BiFeO3 submicroparticles in large scale is of great importance for the utilization of this rhombohedrally distorted perovskite material in applications such as memory storage and spintronic devices and visible photocatalyst for the degradation of organic pollutants. In fact, because of the narrow temperature range of phase stabilization, the fabrication of phase-pure BiFeO3 in large scale remained elusive. We present the synthesis of phase-pure BiFeO3 particles of submicrometric dimensions (246-330 nm average size) through the adjustment of oxidizing/reducing agent ratio in solution combustion process utilizing glycine as reducing agent and nitrate precursors as oxidizing agent...
May 10, 2018: Inorganic Chemistry
Benjamin R Coyac, Guillaume Falgayrac, Guillaume Penel, Alain Schmitt, Thorsten Schinke, Agnès Linglart, Marc D McKee, Catherine Chaussain, Claire Bardet
X-linked hypophosphatemia (XLH) is a skeletal disorder arising from mutations in the PHEX gene, transmitted in most cases as an X-linked dominant trait. PHEX deficiency leads to renal phosphate wasting and hypophosphatemia, as well as impaired mineralization of bone and dentin, resulting in severe skeletal and dental complications. Dentin mineralization defects appear as characteristic, large interglobular spaces resulting from the lack of fusion of calculospherites in the circumpulpal region during the mineralization process...
December 2018: Connective Tissue Research
K A Prosolov, K S Popova, O A Belyavskaya, J V Rau, K A Gross, A Ubelis, Yu P Sharkeev
Bioactive calcium phosphate coatings were deposited by radio-frequency magnetron sputtering from biphasic targets of hydroxyapatite and tricalcium phosphate, sintered at different mass % ratios. According to Raman scattering and X-ray diffraction data, the deposited hydroxyapatite coatings have a disordered structure. High-temperature treatment of the coatings in air leads to a transformation of the quasi-amorphous structure into a crystalline one. A correlation has been observed between the increase in the Ca content in the coatings and a subsequent decrease in Ca in the biphasic targets after a series of deposition processes...
September 2017: Bioactive Materials
Qiang Cai, Jiadan Xue, Qiqi Wang, Yong Du
The dehydration process of gallic acid monohydrate was carried out by heating method and characterized using Raman spectroscopic technique. Density functional theory calculation with B3LYP function is applied to simulate optimized structures and vibrational frequencies of anhydrous gallic acid and its corresponding monohydrated form. Different vibrational modes are assigned by comparison between experimental and theoretical Raman spectra of above two polymorphs. Raman spectra show that vibrational modes of the monohydrate are distinctively different from those of anhydrous one...
May 2, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Briley Bourgeois, Sijun Luo, Brian Riggs, Yaping Ji, Shiva Adireddy, Kurt Schroder, Stan Farnsworth, Douglas B Chrisey, Matthew Escarra
This work reports a new technique for scalable and low temperature processing of nanostructured-TiO2 thin films, allowing for practical manufacturing of TiO2 based devices such as perovskite solar cells at low temperature or on flexible substrates. Dual layers of dense and mesoporous TiO2/graphitic oxide nanocomposite films are synthesized simultaneously using inkjet printing and pulsed photonic irradiation. Investigation of process parameters including precursor concentration (10-20 wt%) and exposure fluence (4...
May 8, 2018: Nanotechnology
Weiren Xia, Heng Wu, Piaojie Xue, Xinhua Zhu
We report on microstructural, magnetic, and optical properties of Pr-doped perovskite manganite (La1 - x Prx )0.67 Ca0.33 MnO3 (LPCMO, x = 0.0-0.5) nanoparticles synthesized via sol-gel process. Structural characterizations (X-ray and electron diffraction patterns, (high resolution) TEM images) provide information regarding the phase formation and the single-crystalline nature of the LPCMO systems. X-ray and electron diffraction patterns reveal that all the LPCMO samples crystallize in perovskite crystallography with an orthorhombic structure (Pnma space group), where the MnO6 octahedron is elongated along the b axis due to the Jahn-Teller effect...
May 4, 2018: Nanoscale Research Letters
Jan Jehlička, Adam Culka, Lilly Mana, Aharon Oren
Cell suspensions of the haloarchaea Halorubrum sodomense and Halobacterium salinarum and the extremely halophilic bacterium Salinibacter ruber (Bacteroidetes) in saturated solutions of chlorides and sulfates (NaCl, KCl, MgSO4 ·7H2 O, K2 SO4 , and (NH4 )Al(SO4 )2 ·12H2 O) were left to evaporate to produce micrometric inclusions in laboratory-grown crystals. Raman spectra of these pinkish inclusions were obtained using a handheld Raman spectrometer with green excitation (532 nm). This portable instrument does not include any microscopic tool...
May 3, 2018: Analytical and Bioanalytical Chemistry
Juan Marcelo Arias, Maria Eugenia Tuttolomondo, Sonia Beatriz Díaz, Aida Ben Altabef
The aim of this work is to analyze the consequences of water redistribution on the structure and stability of phospholipid bilayers induced by Cysteine (Cys). This interaction is studied with dipalmitoylphosphatidylcholine (DPPC) multilamellar vesicles, in gel (30 ºC) and liquid crystalline (50 ºC) state; experimental studies were performed by means of Infrared Spectroscopy (FTIT), Raman Spectroscopy and Differential Scanning Calorimetry (DSC). The polar head sites of the lipid molecules to which water can bind are identified by competition with compounds that form hydrogen bonds such as Cys...
May 2, 2018: Journal of Physical Chemistry. B
Xiujuan Han, Zuchao Meng, Hongfang Zhang, Jianbin Zheng
Various carbon nanomaterials for use in anodic stripping voltammetric analysis of Hg(II), Cu(II), Pb(II) and Cd(II) are screened. Graphene, carbon nanotubes, carbon nanofibers and fullerene (C60 ), dispersed in chitosan (Chit) aqueous solution, are used to modify a glassy carbon electrode (GCE). The fullerene-chitosan modified GCE (C60 -Chit/GCE) displays superior performance in terms of simultaneous determination of the above ions. The electrodes and materials are characterized by electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy, Raman spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy...
May 1, 2018: Mikrochimica Acta
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