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Raman spectra

Shangyuan Feng, Zuci Zheng, Yuanji Xu, Jinyong Lin, Guannan Chen, Cuncheng Weng, Duo Lin, Sufang Qiu, Min Cheng, Zufang Huang, Lan Wang, Rong Chen, Shusen Xie, Haishan Zeng
The search for tumor biomarkers in the urine for cancer diagnosis is currently a hot topic in clinical oncology, with potential for cancer screening and diagnosis. Modified nucleosides excreted through the urine are considered to be a general tumor marker for various cancer types. Herein, we explore a new method that utilizes surface-enhanced Raman scattering (SERS) spectroscopy to obtain a complete biochemical profile of urinary modified nucleosides. In our method, modified nucleosides are first isolated from urine sample utilizing the excellent separation ability of affinity chromatography; then supplemented with gold (Au) nanoparticles as substrate for SERS spectroscopy analysis...
January 5, 2017: Biosensors & Bioelectronics
Lixia Li, Dong Pan, Yongzhou Xue, Xiaolei Wang, Miaoling Lin, Dan Su, Qinglin Zhang, Xuezhe Yu, Hyok So, Dahai Wei, Baoquan Sun, PingHeng Tan, Anlian Pan, Jianhua Zhao
Here we report on the Ga self-catalyzed growth of near full-composition-range energy-gap-tunable GaAs1-xSbx nanowires by molecular-beam epitaxy. GaAs1-xSbx nanowires with different Sb content are systematically grown by tuning the Sb and As fluxes, and the As background. We find that GaAs1-xSbx nanowires with low Sb content can be grown directly on Si (111) substrates (0 ≤ x ≤ 0.60) and GaAs nanowire stems (0 ≤ x ≤ 0.50) by tuning the Sb and As fluxes. To obtain GaAs1-xSbx nanowires with x ranging from 0...
January 19, 2017: Nano Letters
Antoine Azan, Valérie Untereiner, Cyril Gobinet, Ganesh D Sockalingum, Marie Breton, Olivier Piot, Lluis M Mir
Confocal Raman microspectroscopy was used to study the interaction between pulsed electric fields and live cells from a molecular point of view in a non-invasive and label-free manner. Raman signatures of live human adipose-derived mesenchymal stem cells exposed or not to pulsed electric fields (8 pulses, 1 000 V/cm, 100 μs, 1 Hz) were acquired at two cellular locations (nucleus and cytoplasm) and two spectral bands (600-1 800 cm(-1) and 2 800-3 100 cm(-1)). Vibrational modes of proteins (phenylalanine and amide I) and lipids were found to be modified by the electropermeabilization process with a statistically significant difference...
January 19, 2017: Scientific Reports
R Schürmann, I Bald
The excitation of localized surface plasmons in noble metal nanoparticles (NPs) results in different nanoscale effects such as electric field enhancement, the generation of hot electrons and a temperature increase close to the NP surface. These effects are typically exploited in diverse fields such as surface-enhanced Raman scattering (SERS), NP catalysis and photothermal therapy (PTT). Halogenated nucleobases are applied as radiosensitizers in conventional radiation cancer therapy due to their high reactivity towards secondary electrons...
January 18, 2017: Nanoscale
Daniele Moro, Giovanni Valdrè, Ernesto Mesto, Fernando Scordari, Maria Lacalamita, Giancarlo Della Ventura, Fabio Bellatreccia, Salvatore Scirè, Emanuela Schingaro
This study presents a cross-correlated surface and near surface investigation of two phlogopite polytypes from Kasenyi kamafugitic rocks (SW Uganda) by means of advanced Atomic Force Microscopy (AFM), confocal microscopy and Raman micro-spectroscopy. AFM revealed comparable nanomorphology and electrostatic surface potential for the two mica polytypes. A widespread presence of nano-protrusions located on the mica flake surface was also observed, with an aspect ratio (maximum height/maximum width) from 0.01 to 0...
January 18, 2017: Scientific Reports
Pawan Kumar Srivastava, Premlata Yadav, Varsha Rani, Subhasis Ghosh
We report controlled doping in graphene monolayers through charge transfer interaction by trapping selected organic molecules between graphene and underneath substrates. Controllability has been demonstrated in terms of shift in Raman spectra and Dirac point in graphene monolayers. The shift in the Dirac point to positive (negative) gate bias in the transfer characteristics of graphene monolayer based field effect transistor is a clear indication of p(n) type doping in graphene as a consequence of charge transfer interaction between organic molecules and graphene...
January 17, 2017: ACS Applied Materials & Interfaces
Pengfei Li, Yaqi Zhang, Zeming Chen, Peng Gao, Tao Wu, Li-Min Wang
The enthalpy relaxation is performed in the glassy Ge22Se78 to understand the dynamic behaviors. The structure of the glass is examined by X-ray diffraction and Raman spectra. The dynamic parameters such as the fragility, stretching exponent and non-linear factor are determined. A low fragility of m = 27 is exhibited for the chalcogenide, however, the stretching exponent is found not to have a larger value. The enthalpy relaxation spectra are constructed for various glass formers, and a relationship between the fragility and the symmetry of the spectra is demonstrated...
January 17, 2017: Scientific Reports
Panxue Wang, Shintaro Pang, Brooke Pearson, Yayoi Chujo, Lynne McLandsborough, Mingtao Fan, Lili He
A novel method was developed to rapidly concentrate, detect, and differentiate bacteria in skimmed milk using surface enhanced Raman scattering (SERS) mapping on 4-mercaptophenylboronic acid (4-MPBA) functionalized silver (Ag) dendrites. The 4-MPBA functionalized Ag dendritic SERS substrate was used to capture the bacterial cells and enhance the bacterial signal. Salmonella, a significantly important food pathogen, was used as the representative strain to optimize and evaluate the developed method. The capture efficiency for Salmonella enterica subsp enterica BAA1045 (SE1045) was 84...
January 14, 2017: Analytical and Bioanalytical Chemistry
S Saravanan, Anjali C, M Vairamani, T P Sastry, K S Subramanian, N Selvamurugan
Critical-sized bone defects are augmented with cell free and cell loaded constructs to bridge bone defects. Improving the properties of three-dimensional scaffolds with multiple polymers and others is of growing interest in recent decades. Chitosan (CS), a natural biopolymer has limitations for its use in bone regeneration, and its properties can be enhanced with other materials. In the present study, the composite scaffolds containing CS, gelatin (Gn) and graphene oxide (GO) were fabricated through freeze-drying...
January 12, 2017: International Journal of Biological Macromolecules
M C Kirkegaard, J Langford, J Steill, B Anderson, A Miskowiec
Uranyl fluoride (UO2F2) is a hygroscopic powder with two main structural phases: an anhydrous crystal and a partially hydrated crystal of the same R3¯m symmetry. The formally closed-shell electron structure of anhydrous UO2F2 is amenable to density functional theory calculations. We use density functional perturbation theory (DFPT) to calculate the vibrational frequencies of the anhydrous crystal structure and employ complementary inelastic neutron scattering and temperature-dependent Raman scattering to validate those frequencies...
January 14, 2017: Journal of Chemical Physics
Yu V Gerasimova, A S Oreshonkov, N M Laptash, A N Vtyurin, A S Krylov, N P Shestakov, A A Ershov, A G Kocharova
Two ammonium oxofluorovanadates, (NH4)3VO2F4 and (NH4)3VOF5, have been investigated by temperature-dependent infrared and Raman spectroscopy methods to determine the nature of phase transitions (PT) in these compounds. Dynamics of quasioctahedral groups was simulated within the framework of semi-empirical approach, which justified the cis-conformation of VO2F4(3-) (C2v) and the C4v geometry of VOF5(3-). The observed infrared and Raman spectra of both compounds at room temperature (RT) revealed the presence at least of two crystallographically independent octahedral groups...
January 4, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Katarzyna Filipecka, Rafał Miedziński, Maciej Sitarz, Jacek Filipecki, Małgorzata Makowska-Janusik
The Raman, MIR and UV-vis spectroscopy have been used to characterize Omafilcon A material constructing the one of the Proclear family contact lenses. The Omafilcon A is hydrogel material composed of 2-hydroxyethyl methacrylate (HEMA) and 2-methacryloyloxyethyl phosphorylcholine (PC) polymers crosslinked with ethyleneglycol dimethacrylate (EGDMA). Vibrational and electronic properties of the Omafilcon A material were also investigated by quantum chemical calculations. Experimentally obtained Raman, MIR and optical spectra were compared to the theoretical ones calculated applying RHF and DFT methodology...
January 5, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Zarina Ansari, Shib Shankar Singha, Abhijit Saha, Kamalika Sen
A simple room temperature synthesis method of Ni, Cu and Zn sulfide nanoparticles (NPs) in aqueous medium is reported here. The NPs stabilized in aqueous medium by the citrate ions were characterized by UV-vis, ζ potentials, TEM and Raman spectroscopic techniques. The solid NPs could be isolated from the aqueous medium when allowed to stand for a prolonged time (~20h). The solids were also characterized by IR and powder X-ray analysis. The nanoparticles were further used for the development of facile optical sensing and detection of heavy metal ions at trace scale...
January 4, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Yaqi You, Kamol K Das, Huiyuan Guo, Che-Wei Chang, Maria Navas-Moreno, James W Chan, Paul Verburg, Simon R Poulson, Xilong Wang, Baoshan Xing, Yu Yang
Carbonaceous nanomaterials are widely used in industry and consumer products, but concerns have been raised regarding their release into the environment and subsequent impacts on ecosystems and human health. Although many efforts have been devoted to understanding the environmental fate of carbonaceous nanomaterials, information about their microbial transformation is still rare. In this study, we found that within 1 month a polycyclic aromatic hydrocarbon-degrading bacterium, Mycobacterium vanbaalenii PYR-1, was able to degrade both pristine and carboxyl-functionalized multi-walled carbon nanotubes (p-MWCNT and c-MWCNT), as demonstrated by consistent results from high resolution transmission electron microscopy, Raman spectroscopy, and confocal Raman microspectroscopy...
January 12, 2017: Environmental Science & Technology
Kathrin J Mohler, Bernhard J Bohn, Ming Yan, Gwénaëlle Mélen, Theodor W Hänsch, Nathalie Picqué
We extend the technique of multiplex coherent Raman spectroscopy with two femtosecond mode-locked lasers to oscillators of a pulse repetition frequency of 1 GHz. We demonstrate a spectra of liquids, which span 1100  cm<sup>-1</sup> of Raman shifts. At a resolution of 6  cm<sup>-1</sup>, their measurement time may be as short as 5 μs for a refresh rate of 2 kHz. The waiting period between acquisitions is improved 10-fold compared to previous experiments with two lasers of 100-MHz repetition frequencies...
January 15, 2017: Optics Letters
Peter Spenst, Ryan M Young, Brian T Phelan, Michel Keller, Jakub Dostál, Tobias Brixner, Michael R Wasielewski, Frank Würthner
A series of semi-rigid perylene bisimide (PBI) macrocycles with varied ring size containing two to nine PBI chromophores were synthesized in a one-pot reaction and their photophysical properties were characterized by fluorescence, steady-state and transient absorption spectroscopy as well as femtosecond stimulated Raman spectroscopy. These macrocycles show solvent-dependent conformational equilibria and excited-state properties. In dichloromethane the macrocycles prevail in wide-stretched conformations and exhibit upon photoexcitation symmetry-breaking charge separation followed by charge recombination to triplet states, which photosensitize singlet oxygen formation...
January 12, 2017: Journal of the American Chemical Society
Matic Lozinšek, Hélène P A Mercier, David S Brock, Boris Žemva, Gary J Schrobilgen
Examples of coordination compounds in which KrF2 functions as a ligand are very rare. In contrast, XeF2 provides a rich coordination chemistry with a variety of main-group and transition metal cations. The reactions of Mg(AsF6 )2 and KrF2 in HF or BrF5 solvent have afforded [Mg(KrF2 )4 (AsF6 )2 ] and [Mg(KrF2 )4 (AsF6 )2 ]⋅2 BrF5 , respectively, the first examples of a metal cation ligated by KrF2 . Their X-ray crystal structures and Raman spectra show that the KrF2 ligands and [AsF6 ](-) anions are F-coordinated to a naked Mg(2+) cation...
January 12, 2017: Angewandte Chemie
Haitao Li, Han Dai, Yihe Zhang, Wangshu Tong, Hua Gao, Qi An
Electrochemically up-regulated surface-enhanced Raman spectroscopy (E-SERS) effectively increases Raman signal intensities. However, the instrumental requirements and the conventional measurement conditions in an electrolyte cell have hampered its application in fast and on-site detection. To circumvent the inconveniences of E-SERS, we propose a self-energizing substrate that provides electrical potential by converting film deformation from a finger press into stored electrical energy. The substrate combines an energy conversion film and a SERS-active Ag nanowire layer...
January 12, 2017: Angewandte Chemie
Sergii G Nedilko, Sergiy Revo, Vitalii Chornii, Vasyl Scherbatskyi, Kateryna Ivanenko, Maksym Nedielko, Yurii Sementsov, Mykola Skoryk, Andrii Nikolenko, Victor Strelchuk
Micro/nanosized carbon materials were prepared by electrochemical exfoliation method in the forms of the colloids and thin films. Scanning electronic microscopy, optical and luminescent microscopy, and Raman scattering and luminescent spectroscopy were applied for characterization of materials. The wide photoluminescence band in the visible spectral region was observed for each of the samples. The shape of the photoluminescence band depends on excitation wavelength and on the size of the particles. At least two components with maxima at ~580 and ~710 nm can be distinguished in the photoluminescence spectra...
December 2017: Nanoscale Research Letters
Marina Gühlke, Zsuzsanna Heiner, Janina Kneipp
A thiol-modified carotene, 7'-apo-7'-(4-mercaptomethylphenyl)-β-carotene, was used to obtain nonresonant surface-enhanced Raman scattering (SERS) spectra of carotene at an excitation wavelength of 1064 nm, which were compared with resonant SERS spectra at an excitation wavelength of 532 nm. These spectra and surface-enhanced hyper-Raman scattering (SEHRS) spectra of the functionalized carotene were compared with the spectra of nonmodified β-carotene. Using SERS, normal Raman, and SEHRS spectra, all obtained for the resonant case, the interaction of the carotene molecules with silver nanoparticles, as well as the influence of the resonance enhancement and the SERS enhancement on the spectra, were investigated...
September 22, 2016: Journal of Physical Chemistry. C, Nanomaterials and Interfaces
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