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Raman crystallinity

Shujun Wang, Mengge Zheng, Jinglin Yu, Shuo Wang, Les Copeland
The aim of the present study was to characterize the multi-scale structures of ternary complexes of a model system of starch, fatty acid (FA) and β-lactoglobulin (βLG) prepared using a Rapid Visco Analyser (RVA). The addition of βLG to starch-lauric acid or starch-oleic acid RVA pastes resulted in the increased intensity or occurrence of a new viscosity peak during cooling when the RVA protocol was repeated. The viscosity peak was attributed to the formation of starch-βLG-FA complexes. Differential scanning calorimetry (DSC) results showed clearly that starch-βLG-FAs complex was formed as gelatinized starch was cooled in the presence of βLG and FAs...
February 15, 2017: Journal of Agricultural and Food Chemistry
Ashok Zachariah Samuel, Bo-Han Lai, Shih-Ting Lan, Masahiro Ando, Chien-Lung Wang, Hiro-O Hamaguchi
We have recently demonstrated a methodology to estimate the percent crystallinity (PC) of polymers directly with Raman spectroscopy and multivariate curve resolution (MCR) by alternating least-squares (ALS). In the MCR-ALS methodology, the Raman spectrum of a semicrystalline polymer is separated into two constituent components (crystalline and molten/amorphous) and their corresponding concentrations. The methodology necessitates that the Raman spectrum at any temperature to be a linear combination of two MCR spectral components (one molten and one crystalline)...
February 7, 2017: Analytical Chemistry
Vishwas Srivastava, Wenyong Liu, Eric M Janke, Vladislav Kamysbayev, Alexander S Filatov, Chengjun Sun, Byeongdu Lee, Tijana Rajh, Richard D Schaller, Dmitri V Talapin
GaAs is one of the most important semiconductors. However, colloidal GaAs nanocrystals remain largely unexplored because of the difficulties with their synthesis. Traditional synthetic routes either fail to produce pure GaAs phase or result in materials whose optical properties are very different from the behavior expected for quantum dots of direct-gap semiconductors. In this work, we demonstrate a variety of synthetic routes toward crystalline GaAs NCs. By using a combination of Raman, EXAFS, transient absorption, and EPR spectroscopies, we conclude that unusual optical properties of colloidal GaAs NCs can be related to the presence of Ga vacancies and lattice disorder...
February 13, 2017: Nano Letters
Xiaodong Zhang, Yuehua Cong, Baoyan Zhang
As the properties of materials can be determined by their structures, a novel liquid crystalline oligomer (LCO) was first designed and prepared. The LCO possessed reactivity with reduced graphene oxide (RGO) and could be used to modify RGO. Maleimide groups could be grafted onto the RGO surface via the Diels-Alder reaction, whereby the mesogenic units enable the LCO to have optical rotation and excellent liquid crystalline properties, while the carboxyl groups could improve the dispersibility of RGO in solvents and disperse more TiO2 on the surface of modified RGO than on pure RGO...
February 13, 2017: Physical Chemistry Chemical Physics: PCCP
Dae Seok Kim, Apiradee Honglawan, Shu Yang, Dong Ki Yoon
Manipulation of nanomaterials such as nanoparticles (NPs) and nanorods (NRs) to make clusters is of significant interest in material science and nanotechnology due to the unusual collective opto-electric properties in such structures that cannot be found in the individual NPs. This work demonstrates an effective way to arrange NP clusters (NPCs) to make the desired arrays based on removable and NP-guidable liquid crystalline template using sublimation and reconstruction phenomenon. The position of the NPCs is precisely controlled by the defect structure of the liquid crystal (LC), namely toric focal conic domains (TFCDs), during thermal annealing to construct the LC and corresponding NPC structures...
February 16, 2017: ACS Applied Materials & Interfaces
Brad A Steele, Ivan I Oleynik
Two new crystalline compounds, pentazole (N5H) and ammonium pentazolate (NH4)(N5), both featuring cyclo-N5- are discovered using first principles evolutionary search of the nitrogen-rich portion of the hydro-nitrogen binary phase diagram (NxHy, x>y) at high pressures. Both crystals consist of the pentazolate N5- anion and ammonium NH4+ or hydrogen H+ cations. These two crystals are predicted to be thermodynamically stable at pressures above 30 GPa for (NH4)(N5) and 50 GPa for pentazole N5H. The chemical transformation of ammonium azide (NH4)(N3) mixed with di-nitrogen (N2) to ammonium pentazolate (NH4)(N5) is predicted to become energetically favorable above 12...
February 7, 2017: Journal of Physical Chemistry. A
Hye Yun Jeong, Youngjo Jin, Seok Joon Yun, Jiong Zhao, Jaeyoon Baik, Dong Hoon Keum, Hyun Seok Lee, Young Hee Lee
Single-crystalline monolayer hexagonal WS2 is segmented into alternating triangular domains: sulfur-vacancy (SV)-rich and tungsten-vacancy (WV)-rich domains. The WV-rich domain with deep-trap states reveals an electron-dedoping effect, and the electron mobility and photoluminescence are lower by one order of magnitude than those of the SV-rich domain with shallow-donor states. The vacancy-induced strain and doping effects are investigated via Raman and scanning photoelectron microscopy.
February 7, 2017: Advanced Materials
Sarah Karle, Detlef Rogalla, Arne Ludwig, Hans-Werner Becker, Andreas Dirk Wieck, Markus Grafen, Andreas Ostendorf, Anjana Devi
Novel copper ketoiminate compounds were synthesized and for the first time applied for additive-free solution-based deposition of nanoscale copper oxide thin films. The two closely related compounds, namely the bis[4-(2-ethoxyethyl-imino)-3-pentanonato]copper, [Cu(EEKI)2], and bis[4-(3-methoxypropylimino)-3-pentanonato]copper, [Cu(MPKI)2], were characterized by means of elemental and thermogravimetric analysis (TGA), as well as electron impact mass spectrometry (EI-MS). The advantages of these compounds are that they are liquid and possess excellent solubility in common organic solvents in addition to an optimum reactivity towards ambient moisture that enables a facile solution-based approach to nanoscale copper oxide thin films...
February 7, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Guesmi Amira, Bouzidi Chaker, Elhouichet Habib
Undoped and Dy(3+) (0.25, 0.5, 0.8 and 1.5at.%) doped ZnO were elaborated by solid-state reaction method. The ZnO:Dy(3+) samples were characterized using X-ray diffraction (XRD), Raman spectroscopy, UV-vis diffuse reflectance spectroscopy and photoluminescence (PL). The XRD analysis confirms the wurtzite structure of ZnO. A slight shift to lower angles, of the (101) peak, is seen with Dy(3+) content, indicating the substitution of these ions into the ZnO lattice. Raman study indicates the good crystallinity of all ZnO:Dy(3+) samples and confirms the substitution of Zn(2+) by Dy(3+)...
January 22, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Turki Al Hagbani, Sami Nazzal
One approach to enhance curcumin (CUR) aqueous solubility is to use cyclodextrins (CDs) to form inclusion complexes where CUR is encapsulated as a guest molecule within the internal cavity of the water-soluble CD. Several methods have been reported for the complexation of CUR with CDs. Limited information, however, is available on the use of the autoclave process (AU) in complex formation. The aims of this work were therefore to (1) investigate and evaluate the AU cycle as a complex formation method to enhance CUR solubility; (2) compare the efficacy of the AU process with the freeze-drying (FD) and evaporation (EV) processes in complex formation; and (3) confirm CUR stability by characterizing CUR:CD complexes by NMR, Raman spectroscopy, DSC, and XRD...
February 5, 2017: International Journal of Pharmaceutics
Han-Seung Lee, Jitendra Kumar Singh, Mohamed A Ismail
A new technique was accepted to fill the porosity of Al coating applied by arc thermal spray process to enhance corrosion resistance performance in artificial ocean water. The porosity is the inherent property of arc thermal spray coating process. In this study, applied coating was treated with different concentrations of ammonium phosphate mono basic (NH4H2PO4: AP) solution thereafter dried at room temperature and kept in humidity chamber for 7d to deposit uniform film. The corrosion resistance of Al coating and treated samples have been evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic techniques with exposure periods in artificial ocean water...
February 3, 2017: Scientific Reports
Manuel Toledano, Raquel Osorio, Estrella Osorio, Antonio Luis Medina-Castillo, Manuel Toledano-Osorio, Fátima S Aguilera
The aim of this study was to evaluate changes in the mechanical and chemical behavior, and bonding ability at dentin interfaces infiltrated with polymeric nanoparticlesstandard deviations and modes of failure are (NPs) prior to resin application. Dentin surfaces were treated with 37% phosphoric acid followed by application of an ethanol suspension of NPs, Zn-NPs or Ca-NPs followed by the application of an adhesive, Single Bond (SB). Bonded interfaces were stored for 24h, submitted to microtensile bond strength test, and evaluated by scanning electron microscopy...
January 25, 2017: Journal of the Mechanical Behavior of Biomedical Materials
Tobias Wöhrle, Rafet Gündemir, Wolfgang Frey, Friederike Knecht, Andreas Köhn, Sabine Laschat
A series of MIDA (N-methylimino diacetic acid) boronates carrying 4-alkoxy, 3,4-bisalkoxy, or 3,4,5-trisalkoxyphenyl substituents were synthesized and their mesomorphic properties characterized by differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (WAXS, SAXS). Most derivatives were liquid crystalline. In the case of mono- and bisalkoxy-substituted derivatives, already C6 chains induced SmA mesophases despite the bulky MIDA head group. With increasing chain lengths Colh phases replaced SmA phases in the disubstituted series...
January 30, 2017: Chemistry: a European Journal
Daehwan Jung, Joseph Faucher, Samik Mukherjee, Austin Akey, Daniel J Ironside, Matthew Cabral, Xiahan Sang, James Lebeau, Seth R Bank, Tonio Buonassisi, Oussama Moutanabbir, Minjoo Larry Lee
Self-assembled nanocomposites have been extensively investigated due to the novel properties that can emerge when multiple material phases are combined. Growth of epitaxial nanocomposites using lattice-mismatched constituents also enables strain-engineering, which can be used to further enhance material properties. Here, we report self-assembled growth of highly tensile-strained Ge/In0.52Al0.48As (InAlAs) nanocomposites by using spontaneous phase separation. Transmission electron microscopy shows a high density of single-crystalline germanium nanostructures coherently embedded in InAlAs without extended defects, and Raman spectroscopy reveals a 3...
January 27, 2017: Nature Communications
Shigeki Yamamoto, Mai Miyada, Harumi Sato, Hiromichi Hoshina, Yukihiro Ozaki
Low-frequency vibrational modes of lamellar crystalline poly(glycolic acid) (PGA) were measured on Raman and far-infrared (FIR) spectra. Among the observed bands, an FIR band at ∼70 cm(-1) and a Raman band at 125 cm(-1) showed a gradual lower-frequency shift with increasing temperature from 20 °C to the melting point at ∼230 °C. Their polarization direction was perpendicular to the chain axis of PGA. Both spectra were quantum-mechanically simulated with the aid of a fragment method, the Cartesian-coordinate tensor transfer, which enabled an explicit consideration of molecular interactions between two adjacent polymer chains...
February 9, 2017: Journal of Physical Chemistry. B
Karishma B Patel, Bruno Boizot, Sébastien P Facq, Giulio I Lampronti, Sylvain Peuget, Sophie Schuller, Ian Farnan
Molybdenum solubility is a limiting factor to actinide loading in nuclear waste glasses, as it initiates the formation of water-soluble crystalline phases such as alkali molybdates. To increase waste loading efficiency, alternative glass ceramic structures are sought that prove resistant to internal radiation resulting from radioisotope decay. In this study, selective formation of water-durable CaMoO4 in a soda lime borosilicate is achieved by introducing up to 10 mol % MoO3 in a 1:1 ratio to CaO using a sintering process...
January 26, 2017: Inorganic Chemistry
Wenbo Xin, Jenn-Ming Yang, Chao Li, Mark S Goorsky, Larry Carlson, Igor De Rosa
In this work, we have demonstrated a novel route for one-pot synthesis of two dimensional gold nanoplates (2-D AuNPLs) on carbon nanotube (CNT) sheet. Well-defined AuNPLs are grafted onto CNT sheet via a facile hydrothermal reduction process, during which bromine ions are employed as the surfactant for gold anisotropic growth. Scanning electron microscopy (SEM) shows large-scale AuNPLs with micrometer-scaled length and sub-100 nm thickness are deposited uniformly on the CNT sheet. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) results confirm the synthesized AuNPLs are single-crystalline with preferential {111} orientation...
January 20, 2017: ACS Applied Materials & Interfaces
I Georgieva, N Trendafilova, N Dodoff, D Kovacheva
DFT and periodic-DFT (PAW-PBE method, code VASP) calculations have been performed to study the structural and vibrational characteristics of cis-diamminedichloroplatinum(II) (cisplatin) at molecular and outside molecular level. To estimate the effect of the intermolecular interactions in crystal on the structural and vibrational properties of cisplatin, three theoretical models are considered in the present study: monomer (isolated molecule), hydrogen bonded dimer and periodic solid state structures. The work focused on the role of the theoretical models for correct modeling and prediction of geometrical and vibrational parameters of cisplatin...
January 4, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Ying Jin, Anthony P Kotula, Angela R Hight Walker, Kalman B Migler, Young Jong Lee
We use moving-window two-dimensional correlation spectroscopy (MW-2DCOS) for phase-specific Raman analysis of the n-alkane (C21H44) during melting from the crystalline solid phase to the intermediate rotator phase and to the amorphous molten phase. In MW-2DCOS, individual peak-to-peak correlation analysis within a small subset of spectra provides both temperature-resolved and spectrally disentangled Raman assignments conducive to understanding phase-specific molecular interactions and chain configurations. We demonstrate that autocorrelation MW-2DCOS can determine the phase transition temperatures with a higher resolving power than commonly-used analysis methods including individual peak intensity analysis or principal component analysis...
November 2016: Journal of Raman Spectroscopy: JRS
Amine Mezni, Tariq Altalhi, Nesrine Ben Saber, Ali Aldalbahi, Seifeddine Boulehmi, Abel Santos, Dusan Losic
This work aims at introducing the synthesis process of carbon nanotubes (CNTs) inside nanoporous anodic alumina (NAA) templates adopting a catalyst-free chemical vapor deposition (CVD) approach under different conditions. The nanotubular structure of NAA is prepared according to tow-step anodization process. This provides a unique platform to grow CNTs with precisely controlled geometric features. The structural features, crystalline structures and chemical composition of the resulting CNTs-NAA composites were systematically characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), High Resolution Transmission Electron Microscopy (HRTEM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Energy-dispersive X-ray spectroscopy (EDX), Fourier Transform Infrared Spectroscopy (FTIR) as well as Raman spectroscopy...
April 1, 2017: Journal of Colloid and Interface Science
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