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Raman spectra

Sherif Elbasuney, Ashraf F El-Sherif
The instant detection of explosives and explosive-related compounds has become an urgent priority in recent years for homeland security and counter-terrorism applications. Modern techniques should offer enhancement in selectivity, sensitivity, and standoff distances. Miniaturisation, portability, and field-ruggedisation are crucial requirements. This study reports on instant and standoff identification of concealed explosive-related compounds using customized Raman technique. Stokes Raman spectra of common explosive-related compounds were generated and spectrally resolved to create characteristic finger print spectra...
November 30, 2016: Forensic Science International
Fumiya Watanabe, Zeid A Nima, Takumi Honda, Masatoshi Mitsuhara, Minoru Nishida, Alexandru S Biris
Multicomponent nano-agents were designed and built via a core-shell approach to enhance their surface enhanced Raman scattering (SERS) signals. These nano-agents had 36 nm × 12 nm gold nanorod cores coated by 4 nm thick silver shell films and a subsequent thin bifunctional thiolated polyethylene glycol (HS-PEG-COOH) layer. Ambient time-lapsed SERS signal measurements of these functionalized nanorods taken over a two-week period indicated no signal degradation, suggesting that large portions of the silver shells remained in pure metallic form...
December 6, 2016: Nanotechnology
Dedi Liu, Bingbing Liu, Bertil Sundqvist, Dapeng Dong, Zhenghua Li, Dongping Liu
Hollow C70 nano/submicro-crystals with a fcc lattice structure were treated under various high pressure and high temperature conditions. The energy band structure was visibly changed by the high pressure and high temperature treatment, and the luminescence of the treated C70 nano/submicro-crystals were tuned from the visible to the near infrared range. In-situ high pressure experiments at room temperature indicate that pressure plays a key role in the tuning of the band gap and PL properties in C70 nanocrystals, and temperature plays an important role in the formation of stable intermolecular bonds and thus to define the final red-shift of the PL peaks...
December 6, 2016: Scientific Reports
Li-Kun Yang, Xia-Guang Zhang, Fang-Zu Yang, De-Yin Wu, Zhong-Qun Tian, Xiang-Yang Liu
Density functional theory calculations have been used to elucidate the mechanism of the addition reaction of acetaldehyde to the positively charged hydrogenated silicene (H-silicene). We find that the positively charged H-silicene plane could be partially restructured to form a vacant Si site, enabling a further nucleophilic addition reaction. After acetaldehyde molecule attached to the H-silicene plane, two competing pathways are involved in hydrogen abstraction process: a random reaction mechanism and a chain reaction mechanism...
December 6, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Arthur V Cresce, Selena M Russell, Oleg Borodin, Joshua A Allen, Marshall A Schroeder, Michael Dai, Jing Peng, Mallory P Gobet, Steven G Greenbaum, Reginald E Rogers, Kang Xu
Sodium ion batteries are on the cusp of being a commercially available technology. Compared to lithium ion batteries, sodium ion batteries can potentially offer an attractive dollar-per-kilowatt-hour value, though at the penalty of reduced energy density. As a materials system, sodium ion batteries present a unique opportunity to apply lessons learned in the study of electrolytes for lithium ion batteries; specifically, the behavior of the sodium ion in an organic carbonate solution and the relationship of ion solvation with electrode surface passivation...
December 5, 2016: Physical Chemistry Chemical Physics: PCCP
Deepika Chaturvedi, Sai A Balaji, Vinay Kumar Bn, Freek Ariese, Siva Umapathy, Annapoorni Rangarajan
Breast cancer is the most prevalent cause of cancer-associated death in women the world over, but if detected early it can be treated successfully. Therefore, it is important to diagnose this disease at an early stage and to understand the biochemical changes associated with cellular transformation and cancer progression. Deregulated lipid metabolism has been shown to contribute to cell transformation as well as cancer progression. In this study, we monitored the biomolecular changes associated with the transformation of a normal cell into an invasive cell associated with breast cancer using Raman microspectroscopy...
November 28, 2016: Biosensors
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
Dinh Bao Nguyen, Thanh Danh Nguyen, Sangsoo Kim, Sang-Woo Joo
Spectral differences between cytosine (Cyt) and 5-methylcytosine (5MC) were investigated by means of Raman spectroscopy with a combination of density functional theory (DFT) calculations. Surface-enhanced Raman scattering (SERS) revealed discriminating peaks of 5MC from those of Cyt upon adsorption on gold nanoparticles (AuNPs). Among the notable features, the multiple bands between 850 and 700cm(-1) for the ring-breathing modes of 5MC and Cyt could be correlated well with the simulated spectra based on the DFT calculations of the adsorbates on the gold cluster atoms...
November 9, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Nan Wang, Kai Ren, Rong Jia, Wenting Chen, Ruirui Sun
BACKGROUND: Manganese peroxidase (MnP) from Irpex lacteus F17 has been shown to have a strong ability to degrade recalcitrant aromatic pollutants. In this study, a recombinant MnP from I. lacteus F17 was expressed in Escherichia coli Rosetta (DE3) in the form of inclusion bodies, which were refolded to achieve an active enzyme. Further, we optimized the in vitro refolding conditions to increase the recovery yield of the recombinant protein production. Additionally, we attempted to express recombinant MnP in soluble form in E...
December 1, 2016: BMC Biotechnology
Baolai Yang, Hanwei Zhang, Chen Shi, Xiaolin Wang, Pu Zhou, Xiaojun Xu, Jinbao Chen, Zejin Liu, Qisheng Lu
Transverse mode instability (TMI) is one of the main limiting factors in kW-level fiber lasers. Unlike fiber amplifiers, TMI in fiber laser oscillators attracts less attention from researchers. In this work, we construct an all-fiber ytterbium-doped laser oscillator and investigate the performance in co-pumping and bidirectional-pumping configurations, respectively. In the co-pumping scheme, TMI occurs at ~1.6kW and restricts further output power scaling. Different from the characteristic of dynamic TMI in fiber amplifiers, quasi-static TMI is observed in the laser oscillator...
November 28, 2016: Optics Express
Jun Young Kim, Jeongyong Kim, Jinsoo Joo
Two-dimensional (2-D) transition metal dichalcogenides, such as MoS<sub>2</sub>, WSe<sub>2</sub>, and WS<sub>2</sub>, are promising materials for application in field effect transistors, optoelectronics, and sensing devices. In this study, 2-D WSe<sub>2</sub> samples with various numbers of layers were hybridized with functionalized gold nanoparticles (Au-NPs) to achieve surface-enhanced Raman scattering (SERS). The nanoscale Raman and photoluminescence spectra of the WSe<sub>2</sub> layers and WSe<sub>2</sub>/Au-NP hybrids were measured using a high-resolution laser confocal microscope...
November 28, 2016: Optics Express
Jean-Emmanuel Clément, Aymeric Leray, Alexandre Bouhelier, Eric Finot
In this contribution, we provide new insights on the temporal fluctuations of surface enhanced Raman spectra (SERS) of large single molecules such as proteins. Because they can only fit partly into small active volume, SERS analysis is referred to spectral pointillism where only protein subdomains are shined and the whole protein landscape is built from the dynamics of successive individual spectra. By applying our approach on bovine serum albumin, we show that single protein subdomains are mostly comprised of three distinct amino acids...
December 1, 2016: Physical Chemistry Chemical Physics: PCCP
Afik Shachar, Nitzan Mayorkas, Hanan Sachs, Ilana Bar
Fluorination is considered as a possible means for alteration of conformational landscapes in molecules. The effect of fluorine substitution was studied here by measuring the vibronic and vibrational spectra of gas phase 2-(4-fluoro-phenyl)-ethylamine (4-FPEA) by resonant two-photon ionization (R2PI) and by ionization-loss stimulated Raman spectroscopy (ILSRS). The measurement of survey ILSR spectra of 4-FPEA in the amino group region allowed to associate the bands in the R2PI spectrum to origin and vibronic transitions of the ground (S0) to the excited (S1) electronic states of three different conformers...
December 1, 2016: Physical Chemistry Chemical Physics: PCCP
Jakub Maciej Surmacki, Laura Ansel-Bollepalli, Francesca Pischiutta, Elisa R Zanier, Ari Ercole, Sarah Elizabeth Bohndiek
Traumatic brain injury (TBI) constitutes a major cause of death and long-term disability. At present, we lack methods to non-invasively track tissue biochemistry and hence select appropriate interventions for patients. We hypothesized that detailed label-free vibrational chemical analysis of focal TBI could provide such information. We assessed the early spatial and temporal changes in tissue biochemistry that are associated with brain injury in mice. Numerous differences were observed in the spectra of the contusion core and pericontusional tissue between 2 and 7 days...
December 1, 2016: Analyst
Sagnik Basuray, Avinash Pathak, Sangho Bok, Biyan Chen, Steven C Hamm, Cherian J Mathai, Suchismita Guha, Keshab Gangopadhyay, Shubhra Gangopadhyay
Classical methods for enhancing the electromagnetic field from substrates for spectroscopic applications, such as surface-enhanced Raman spectroscopy (SERS), have involved the generation of hotspots through directed self-assembly of nanoparticles or by patterning nanoscale features using expensive nanolithography techniques. A novel large-area, cost-effective soft lithographic technique involving glancing angle deposition (GLAD) of silver on polymer gratings is reported here. This method produces hierarchical nanostructures with high enhancement factors capable of analyzing single-molecule SERS...
December 1, 2016: Nanotechnology
K V Jovan Jose, Krishnan Raghavachari
The molecules-in-molecules (MIM) fragment-based method has recently been adapted to evaluate the chiroptical (vibrational circular dichroism [VCD] and Raman optical activity [ROA]) spectra of large molecules such as peptides. In the MIM-VCD and MIM-ROA methods, the relevant higher energy derivatives of the parent molecule are assembled from the corresponding derivatives of smaller fragment subsystems. In addition, the missing long-range interfragment interactions are accounted at a computationally less expensive level of theory (MIM2)...
December 2016: Chirality
Renan Belli, Michael Wendler, Dominique de Ligny, Maria Rita Cicconi, Anselm Petschelt, Herwig Peterlik, Ulrich Lohbauer
OBJECTIVE: A deeper understanding of the mechanical behavior of dental restorative materials requires an insight into the materials elastic constants and microstructure. Here we aim to use complementary methodologies to thoroughly characterize chairside CAD/CAM materials and discuss the benefits and limitations of different analytical strategies. METHODS: Eight commercial CAM/CAM materials, ranging from polycrystalline zirconia (e.max ZirCAD, Ivoclar-Vivadent), reinforced glasses (Vitablocs Mark II, VITA; Empress CAD, Ivoclar-Vivadent) and glass-ceramics (e...
November 24, 2016: Dental Materials: Official Publication of the Academy of Dental Materials
Cynthia Hanson, Michael Sieverts, Elizabeth Vargis
Raman spectroscopy has been used for decades to detect and identify biological substances as it provides specific molecular information. Spectra collected from biological samples are often complex, requiring the aid of data truncation techniques such as principal component analysis (PCA) and multivariate classification methods. Classification results depend on the proper selection of principal components (PCs) and how PCA is performed (scaling and/or centering). There are also guidelines for choosing the optimal number of PCs such as a scree plot, Kaiser criterion, or cumulative percent variance...
November 25, 2016: Applied Spectroscopy
Wen-Juan Tian, Qiang Chen, Xin-Xin Tian, Yue-Wen Mu, Hai-Gang Lu, Si-Dian Li
Motifs of planar metalloborophenes, cage-like metalloborospherenes, and metal-centered double-ring tubular boron species have been reported. Based on extensive first-principles theory calculations, we present herein the possibility of doping the quasi-planar C2v B56 (A-1) with an alkaline-earth metal to produce the penta-ring tubular Ca©B56 (B-1) which is the most stable isomer of the system obtained and can be viewed as the embryo of metal-doped (4,0) boron α-nanotube Ca©BNT(4,0) (C-1). Ca©BNT(4,0) (C-1) can be constructed by rolling up the most stable boron α-sheet and is predicted to be metallic in nature...
November 25, 2016: Scientific Reports
Tory M Schaaf, Kurt C Peterson, Benjamin D Grant, David D Thomas, Gregory D Gillispie
We have developed a microplate reader that records a complete high-quality fluorescence emission spectrum on a well-by-well basis under true high-throughput screening (HTS) conditions. The read time for an entire 384-well plate is less than 3 min. This instrument is particularly well suited for assays based on fluorescence resonance energy transfer (FRET). Intramolecular protein biosensors with genetically encoded green fluorescent protein (GFP) donor and red fluorescent protein (RFP) acceptor tags at positions sensitive to structural changes were stably expressed and studied in living HEK cells...
November 22, 2016: Journal of Biomolecular Screening
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