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Raman spectroscopy

Abdul K Parchur, Qifei Li, Anhong Zhou
We report the synthesis, characterization, and application of Prussian blue (PB) functionalized CaMoO4:Eu@SiO2@Au nanorod hybrid nanoparticles (HNPs), with multimodal capabilities such as fluorescence imaging, surface-enhanced Raman spectroscopy (SERS) detection and photothermal therapy (PTT). The average size of CaMoO4:Eu@SiO2 NPs was 206 nm. The HNPs are highly dispersible in water for several weeks without settling and show a strong absorption in the near-infrared region, overlapping with the PB absorption between 600 nm and 1000 nm and the surface plasmon resonance of Au nanorods around 800 nm...
October 21, 2016: Biomaterials Science
S Drijkoningen, S D Janssens, P Pobedinskas, S Koizumi, M K Van Bael, K Haenen
Nanocrystalline diamond (NCD) membranes are promising candidates for use as sensitive pressure sensors. NCD membranes are able to withstand harsh conditions and are easily fabricated on glass. In this study the sensitivity of heavily boron doped NCD (B:NCD) pressure sensors is evaluated with respect to different types of supporting glass substrates, doping levels and membrane sizes. Higher pressure sensing sensitivities are obtained for membranes on Corning Eagle 2000 glass, which have a better match in thermal expansion coefficient with diamond compared to those on Schott AF45 glass...
October 21, 2016: Scientific Reports
Daniel Jaeger, Christian Pilger, Henning Hachmeister, Elina Oberländer, Robin Wördenweber, Julian Wichmann, Jan H Mussgnug, Thomas Huser, Olaf Kruse
Oleaginous photosynthetic microalgae hold great promise as non-food feedstocks for the sustainable production of bio-commodities. The algal lipid quality can be analysed by Raman micro-spectroscopy, and the lipid content can be imaged in vivo in a label-free and non-destructive manner by coherent anti-Stokes Raman scattering (CARS) microscopy. In this study, both techniques were applied to the oleaginous microalga Monoraphidium neglectum, a biotechnologically promising microalga resistant to commonly applied lipid staining techniques...
October 21, 2016: Scientific Reports
Martin Hetzl, Max Kraut, Julia Winnerl, Luca Francaviglia, Markus Döblinger, Sonja Matich, Anna Fontcuberta I Morral, Martin Stutzmann
We demonstrate the selective area growth of GaN-AlGaN core-shell nanowire heterostructures directly on Si (111). Photoluminescence spectroscopy on as-grown nanowires reveals a strong blueshift of the GaN band gap from 3.40 eV to 3.64 eV at room temperature. Raman measurements relate this shift to compressive strain within the GaN core. On the nano-scale, cathodoluminescence spectroscopy and scanning transmission electron microscopy prove the homogeneity of strain-related luminescence along the NW axis and the absence of significant fluctuations within the shell, respectively...
October 21, 2016: Nano Letters
Thitaphat Ngernsutivorakul, Cynthia M Cipolla, Colleen E Dugan, Shi Jin, Michael D Morris, Robert T Kennedy, Francis W L Esmonde-White
Fiber optics coupled to components such as lenses and mirrors have seen extensive use as probes for Raman and fluorescence measurements. Probes can be placed directly on or into a sample to allow for simplified and remote application of these optical techniques. The size and complexity of such probes however limits their application. We have used microfabrication in polydimethylsiloxane (PDMS) to create compact probes that are 0.5 mm thick by 1 mm wide. The miniature probes incorporate pre-aligned mirrors, lenses, and two fiber optic guides to allow separate input and output optical paths suitable for Raman and fluorescence spectroscopy measurements...
October 20, 2016: Analytical and Bioanalytical Chemistry
Justin M Gorham, William A Osborn, Jeremiah W Woodcock, Keana C K Scott, John M Heddleston, Angela R Hight Walker, Jeffrey W Gilman
To better assess risks associated with nano-enabled products including multiwalled carbon nanotubes (MWCNT) within polymer matrices, it is important to understand how MWCNT are dispersed throughout the composite. The current study presents a method which employs imaging X-ray photoelectron spectroscopy (XPS) to chemically detect spatially segregated MWCNT rich regions at an epoxy composites surface by exploiting differential charging. MWCNT do not charge due to high conductivity and have previously been shown to energetically separate from their insulating surroundings when characterized by XPS...
January 2016: Carbon
Nicolas Marinval, Pierre Saboural, Oualid Haddad, Murielle Maire, Kevin Bassand, Frederic Geinguenaud, Nadia Djaker, Khadija Ben Akrout, Marc Lamy de la Chapelle, Romain Robert, Olivier Oudar, Erwan Guyot, Christelle Laguillier-Morizot, Angela Sutton, Cedric Chauvierre, Frederic Chaubet, Nathalie Charnaux, Hanna Hlawaty
Herein we investigate the structure/function relationships of fucoidans from Ascophyllum nodosum to analyze their pro-angiogenic effect and cellular uptake in native and glycosaminoglycan-free (GAG-free) human endothelial cells (HUVECs). Fucoidans are marine sulfated polysaccharides, which act as glycosaminoglycans mimetics. We hypothesized that the size and sulfation rate of fucoidans influence their ability to induce pro-angiogenic processes independently of GAGs. We collected two fractions of fucoidans, Low and Medium Molecular Weight Fucoidan (LMWF and MMWF, respectively) by size exclusion chromatography and characterized their composition (sulfate, fucose and uronic acid) by colorimetric measurement and Raman and FT-IR spectroscopy...
October 17, 2016: Marine Drugs
M Moskvin, D Horák
Maghemite (gamma-Fe2O3) nanoparticles, 12 nm in size, were prepared by co-precipitation of Fe(II) and Fe(III) chlorides with ammonium hydroxide and oxidation with hydrogen peroxide. To achieve stability and biocompatibility, obtained particles were coated with silica, to which glucose and ascorbic acid were bound by different mechanisms. The composite particles were thoroughly characterized by transmission electron microscopy, dynamic light scattering, elemental analysis, and FT-Raman and fluorescence spectroscopy to determine composition, morphology, size and its distribution, zeta-potential, and scavenging of peroxyl and hydroxyl radicals...
October 20, 2016: Physiological Research
Yuqin Zou, Alex S Walton, Ian A Kinloch, Robert A W Dryfe
A study of the differences between the capacitance of freshly exfoliated highly ordered pyrolytic graphite (HOPG, sample denoted FEG), HOPG aged in air (denoted AAG) and aged in an inert atmosphere (hereafter IAG) is presented in this work. The FEG is found to be more hydrophilic than AAG and IAG since the aqueous electrolyte contact angle (CA) increases from 61.7o to 72.5o and 81.8o after aging in Ar and air, respectively. Electrochemical impedance spectroscopy (EIS) shows the FEG has higher intrinsic capacitance (6...
October 19, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Aaron J Celestian, Caleb J Chappell, Melinda J Rucks, Pauline Norris
The ion exchange of yttrium, one of the five most critical rare-earth elements as outlined by the U.S. Department of Energy, into ETS-4 is a dynamic, multistep ion exchange process. The ion exchange process was followed using in situ time-resolved Raman spectroscopy, and the crystal structures of the pre-exchange and post-exchange forms were determined by single-crystal X-ray diffraction. In situ Raman spectroscopy is an ideal tool for this type of study, as it measures the spectral changes that are a result of molecular geometry changes at fast time intervals, even where symmetry and unit volume changes are minimally detected by X-ray diffraction...
October 19, 2016: Inorganic Chemistry
Mouritz N Svenson, Randall E Youngman, Yuanzheng Yue, Sylwester J Rzoska, Michal Bockowski, Lars R Jensen, Morten M Smedskjaer
The structure and properties of glass can be modified through compression near the glass transition temperature (Tg), and such modified structure and properties can be maintained at ambient temperature and pressure. However, once the compressed glass undergoes annealing near Tg at ambient pressure, the modified structure and properties will relax. The challenging question is how the property relaxation is correlated with both the local and the medium-range structural relaxation. In this paper, we answer this question by studying the volume (density) and structural relaxation of a sodium borate glass that has first been pressure-quenched from its Tg at 1 GPa, and then annealed at ambient pressure under different temperature-time conditions...
October 19, 2016: Physical Chemistry Chemical Physics: PCCP
Bikramjeet Singh, Gurpreet Kaur, Paviter Singh, Kulwinder Singh, Baban Kumar, Ankush Vij, Manjeet Kumar, Rajni Bala, Ramovatar Meena, Ajay Singh, Anup Thakur, Akshay Kumar
Highly water dispersible boron based compounds are innovative and advanced materials which can be used in Boron Neutron Capture Therapy for cancer treatment (BNCT). Present study deals with the synthesis of highly water dispersible nanostructured Boron Nitride (BN). Unique and relatively low temperature synthesis route is the soul of present study. The morphological examinations (Scanning/transmission electron microscopy) of synthesized nanostructures showed that they are in transient phase from two dimensional hexagonal sheets to nanotubes...
October 19, 2016: Scientific Reports
Stefan Hofbauer, Georg Mlynek, Lisa Milazzo, Dominic Pühringer, Daniel Maresch, Irene Schaffner, Paul G Furtmüller, Giulietta Smulevich, Kristina Djinović-Carugo, Christian Obinger
Heme biosynthesis in Gram positive bacteria follows a recently described coproporphyrin-dependent pathway with HemQ catalyzing the decarboxylation of coproheme to heme b. Here we present the first crystal structure of a HemQ (homopentameric coproproheme-HemQ from Listeria monocytogenes) at 1.69 Å resolution and the conversion of coproheme to heme b followed by UV-vis and resonance Raman spectroscopy as well as mass spectrometry. The ferric 5-coordinated coproheme iron of HemQ is weakly bound by a neutral proximal histidine H174...
October 18, 2016: FEBS Journal
Yao Tian, Kenneth S Burch
Raman spectroscopy is a powerful technique, widely used in both academia and industry. In part, the technique's extensive use stems from its ability to uniquely identify and image various material parameters: composition, strain, temperature, lattice/excitation symmetry, and magnetism in bulk, nano, solid, and organic materials. However, in nanomaterials and samples with low thermal conductivity, these measurements require long acquisition times. On the other hand, charge-coupled device (CCD) detectors used in Raman microscopes are vulnerable to cosmic rays...
October 17, 2016: Applied Spectroscopy
Suman Chowdhury, Debnarayan Jana
Inspired by the success of graphene, various two dimensional (2D) structures in free standing (FS) (hypothetical) form and on different substrates have been proposed recently. Silicene, a silicon counterpart of graphene, is predicted to possess massless Dirac fermions and to exhibit an experimentally accessible quantum spin Hall effect. Since the effective spin-orbit interaction is quite significant compared to graphene, buckling in silicene opens a gap of 1.55 meV at the Dirac point. This band gap can be further tailored by applying in plane stress, an external electric field, chemical functionalization and defects...
October 18, 2016: Reports on Progress in Physics
Myriam Barrejón, María J Gómez-Escalonilla, José Luis G Fierro, Pilar Prieto, José R Carrillo, Antonio M Rodríguez, Gonzalo Abellán, Ma Cruz López-Escalante, Mercedes Gabás, Juan T López-Navarrete, Fernando Langa
After the feasibility of the 1,3-dipolar cycloaddition reaction between nitrile imines and exfoliated graphene by density functional theory calculations was proved, very few-layer graphene was effectively functionalized using this procedure. Hydrazones with different electronic properties were used as precursors for the 1,3-dipoles, and microwave irradiation as an energy source enabled the reaction to be performed in a few minutes. The anchoring of organic addends on the graphene surface was confirmed by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis...
October 18, 2016: Physical Chemistry Chemical Physics: PCCP
C Weyrich, M Drögeler, J Kampmeier, M Eschbach, G Mussler, T Merzenich, T Stoica, I E Batov, J Schubert, L Plucinski, B Beschoten, C M Schneider, C Stampfer, D Grützmacher, Th Schäpers
Ternary (Bi1-x Sb x )2Te3 films with an Sb content between 0 and 100% were deposited on a Si(1 1 1) substrate by means of molecular beam epitaxy. X-ray diffraction measurements confirm single crystal growth in all cases. The Sb content is determined by x-ray photoelectron spectroscopy. Consistent values of the Sb content are obtained from Raman spectroscopy. Scanning Raman spectroscopy reveals that the (Bi1-x Sb x )2Te3 layers with an intermediate Sb content show spatial composition inhomogeneities. The observed spectra broadening in angular-resolved photoemission spectroscopy (ARPES) is also attributed to this phenomena...
October 17, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Moamen S Refat, Hosam A Saad, Abdel Majid A Adam, Mohamed A Al-Omar, Ahmed M Naglah
The topic of charge-transfer (CT) complexation of vital drugs has attracted considerable attention in recent years owing to their significant physical and chemical properties. In this study, CT complexes derived from the reaction of the anti-hyperuricemic drug allopurinol (Allop) with organic p-acceptors [(picric acid (PA), dichlorodicyanobenzoquinone (DDQ) and chloranil (CHL)] were prepared, isolated and characterized by a range of physicochemical methods, such as IR, Raman, 1H NMR and 13C NMR spectroscopy...
December 1, 2016: Acta Pharmaceutica
Sumit Murab, Shibu Chameettachal, Sourabh Ghosh
Macular corneal dystrophy (MCD) is characterized by multiple punctate gray-white opacities in the corneal stromal region, due to the accumulation of abnormally sulfated keratan sulfates. We attempted to develop an in vitro model of MCD by simulating the sulfation inhibition using sodium chlorate, a chemical inhibitor of 3'-phosphoadenosine-5'-phosphosulfate (PAPs). The SEM and micro-Raman spectroscopy results showed the hallmark feature of MCD. Further the gene expression studies elucidated the direct effect of sulfation inhibition on the WNT pathway, that in turn downregulated production of matrix metalloproteinases (MMPs), which causes abnormal matrix deposits leading to loss of transparency in vivo...
October 17, 2016: Laboratory Investigation; a Journal of Technical Methods and Pathology
Yushi Yang, Zhou Mao, Wenjie Huang, Lihua Liu, Junli Li, Jialiang Li, Qingzhi Wu
CeO2 nanoparticles (NPs) have been well demonstrated as an antioxidant in protecting against oxidative stress-induced cellular damages and a potential therapeutic agent for various diseases thanks to their redox enzyme-mimicking activities. The Ce(3+)/Ce(4+) ratio and oxygen vacancies on the surface have been considered as the major originations responsible for the redox enzyme-mimicking activities of CeO2 NPs. Herein, CeO2 nanostructures (nanocubes and nanorods) exposed different facets were synthesized via a facile hydrothermal method...
October 17, 2016: Scientific Reports
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