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https://www.readbyqxmd.com/read/30120630/effects-of-tip-sonication-parameters-on-liquid-phase-exfoliation-of-graphite-into-graphene-nanoplatelets
#1
Xinzhi Cai, Zeyi Jiang, Xinru Zhang, Xinxin Zhang
Graphene nanoplatelets (GNPs) can be produced by exfoliating graphite in solvents via high-power tip sonication. In order to understand the influence of tip sonication parameters on graphite exfoliation to form GNPs, three typical flaked graphite samples were exfoliated into GNPs via tip sonication at power of 60, 100, 200, or 300 W for 10, 30, 60, 90, 120, or 180 min. The concentration of GNP dispersions, the size and defect density of the produced GNPs, and the sedimentation behavior of GNP dispersions produced under various tip sonication parameters were determined...
August 17, 2018: Nanoscale Research Letters
https://www.readbyqxmd.com/read/30119563/low-repetition-rate-all-fiber-integrated-optical-parametric-oscillator-for-coherent-anti-stokes-raman-spectroscopy
#2
Kangwen Yang, Shikai Zheng, Yuxing Wu, Pengbo Ye, Kun Huang, Qiang Hao, Heping Zeng
All-fiber optical parametric oscillator (OPO), offering advantages like robustness, compactness and low lost, has attracted intense interest in coherent anti-Stokes Raman scattering spectroscopy. In typical fiber-based OPO configurations, detrimental nonlinear effects due to intense pump field in fiber coupling devices would inevitably degrade the spectral purity and conversion efficiency, especially when the OPO operated at low repetition rates. Here we demonstrated a new OPO design by placing the main amplifier inside the cavity, where the amplified pump pulses were directly coupled into the nonlinear fiber...
June 25, 2018: Optics Express
https://www.readbyqxmd.com/read/30116687/defect-formation-in-multiwalled-carbon-nanotubes-under-low-energy-he-and-ne-ion-irradiation
#3
Santhana Eswara, Jean-Nicolas Audinot, Brahime El Adib, Maël Guennou, Tom Wirtz, Patrick Philipp
The mechanical, structural, electronic and magnetic properties of carbon nanotubes can be modified by electron or ion irradiation. In this work we used 25 keV He+ and Ne+ ion irradiation to study the influence of fluence and sample thickness on the irradiation-induced damage of multiwalled carbon nanotubes (MWCNTs). The irradiated areas have been characterised by correlative Raman spectroscopy and TEM imaging. In order to preclude the Raman contribution coming from the amorphous carbon support of typical TEM grids, a new methodology involving Raman inactive Au TEM grids was developed...
2018: Beilstein Journal of Nanotechnology
https://www.readbyqxmd.com/read/30114813/optical-fibre-tip-probes-for-sers-numerical-study-for-design-considerations
#4
Tanya Hutter, Stephen R Elliott, Sumeet Mahajan
Enhancement of sub-wavelength optical fields using sub-micron plasmonic probes has found many applications in chemical, material, biological and medical sciences. The enhancement is via localised surface-plasmon resonance (LSPR) which enables the highly sensitive vibrational-spectroscopy technique of surface-enhanced Raman scattering (SERS). Combining SERS with optical fibres can allow the monitoring of biochemical reactions in situ with high resolution. Here, we study the electromagnetic-field enhancement of a tapered optical fibre-tip coated with gold nanoparticles (AuNPs) using finite-element simulations...
June 11, 2018: Optics Express
https://www.readbyqxmd.com/read/30114030/holographically-controlled-three-dimensional-atomic-population-patterns
#5
Adam Selyem, Sylvain Fayard, Thomas W Clark, Aidan S Arnold, Neal Radwell, Sonja Franke-Arnold
The interaction of spatially structured light fields with atomic media can generate spatial structures inscribed in the atomic populations and coherences, allowing for example the storage of optical images in atomic vapours. Typically, this involves coherent optical processes based on Raman or EIT transitions. Here we study the simpler situation of shaping atomic populations via spatially dependent optical depletion. Using a near resonant laser beam with a holographically controlled 3D intensity profile, we imprint 3D population structures into a thermal rubidium vapour...
July 9, 2018: Optics Express
https://www.readbyqxmd.com/read/30112649/imaging-of-growth-factors-on-a-human-tooth-root-canal-by-surface-enhanced-raman-spectroscopy
#6
Václav Ranc, Radovan Žižka, Zuzana Chaloupková, Juraj Ševčík, Radek Zbořil
Endodontic treatment of immature permanent teeth with necrotic pulp poses several clinical challenges and is one of the most demanding interventions in endodontics. Recently, with new discoveries in the field of tissue engineering, novel treatment protocols have been established. The most promising treatment modality is revascularization, whose integral part is the exposure of collagen matrix and embedded growth factors. However, optimization of the treatment protocol requires a development of analytical procedures able to analyze growth factors directly on the sample surface...
August 15, 2018: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/30111103/uncovering-the-hidden-excited-state-toward-fluorescence-of-an-intracellular-ph-indicator
#7
Longteng Tang, Liangdong Zhu, Yanli Wang, Chong Fang
Intracellular pH (pHi ) imaging is of paramount importance for life sciences. In this work, we implement the ultrafast electronic and stimulated Raman spectroscopies to unravel the fluorescence mechanism of an excitation-ratiometric pHi indicator in basic aqueous solution. After photoexcitation of the pHi indicator HPTS, a hidden charge-transfer (CT) state following the locally excited (LE) state is uncovered as an essential step prior to fluorescence and this LE → CT transition is gated by ultrafast solvation dynamics...
August 17, 2018: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/30110153/sers-based-quantification-of-biomarker-expression-at-the-single-cell-level-enabled-by-gold-nanostars-and-truncated-aptamers
#8
Manjari Bhamidipati, Hyeon-Yeol Cho, Ki Bum Lee, Laura Fabris
Surface-enhanced Raman spectroscopy (SERS)-based biosensors have been used increasingly over the past few years for cancer detection and diagnosis. SERS-based imaging offers excellent sensitivity and has advantages over other detection techniques such as fluorescence. In this study, we developed a novel biosensor to detect the cancer biomarker epithelial cell adhesion molecule (EpCAM) and quantify its expression at the single cell level. EpCAM is one of the most commonly expressed markers on a variety of cancer cells; importantly it has been suggested that reduction of its expression levels could be associated to the epithelial to mesenchymal transition (EMT), and thus to the onset of metastasis...
August 15, 2018: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/30106560/roadblocks-in-cation-diffusion-pathways-implications-of-phase-boundaries-for-li-ion-diffusivity-in-an-intercalation-cathode-material
#9
Yuting Luo, Luis R De Jesus, Justin L Andrews, Abhishek Parija, Nathan Fleer, Daniel Juarez Robles, Partha P Mukherjee, Sarbajit Banerjee
Increasing intercalation of Li-ions brings about distortive structural transformations in several canonical intercalation hosts. Such phase transformations require the energy dissipative creation and motion of dislocations at the interface between the parent lattice and the nucleated Li-rich phase. Phase inhomogeneities within particles and across electrodes give rise to pronounced stress gradients, which can result in capacity fading. How such transformations alter Li-ion diffusivities remains much less explored...
August 14, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/30106346/translabial-us-preoperative-detection-of-midurethral-sling-erosion-in-stress-urinary-incontinence
#10
Karoly A Viragh, Seth A Cohen, Luyao Shen, Nicole Kurzbard-Roach, Shlomo Raz, Steven S Raman
Purpose To evaluate the performance of translabial (TL) US in preoperative detection of sling erosion into pelvic organs with cystourethroscopic and surgical correlation. Materials and Methods The study cohort included women who underwent surgery at a subspecialty center (from 2008 to 2016) for suspected mesh complications in the setting of previous midurethral sling placement for stress urinary incontinence (from 1999 to 2012) with available preoperative TL US imaging. Clinical information, the finding of sling erosion identified intraoperatively and at cystourethroscopy, and blinded dual-reader radiologic analysis of the TL US studies for mesh location (intraluminal, mural, or extramural) relative to pelvic organs (bladder, urethra, vagina, or rectum) were evaluated...
August 14, 2018: Radiology
https://www.readbyqxmd.com/read/30106072/diversity-among-endothelial-cell-lines-revealed-by-raman-and-fourier-transform-infrared-spectroscopic-imaging
#11
Ewelina Szafraniec, Ewelina Wiercigroch, Krzysztof Czamara, Katarzyna Majzner, Emilia Staniszewska-Slezak, Katarzyna M Marzec, Kamilla Malek, Agnieszka Kaczor, Malgorzata Baranska
Growing interest in the role of endothelium under physiological and pathological conditions has led to an increasing demand for its representative in vitro models especially suitable for drug tests and medical diagnostics. There are several endothelial cell lines commercially available whose biochemistry, and hence response to various stimuli, can be different. Recently, two vibrational techniques, Raman and Fourier-transform infrared microscopy, have been found to be potent tools for studying the biochemical composition of a single cell in an easy, rapid and label-free way...
August 14, 2018: Analyst
https://www.readbyqxmd.com/read/30099316/facilitated-delignification-in-cad-deficient-transgenic-poplar-studied-by-confocal-raman-spectroscopy-imaging
#12
Jana S Segmehl, Tobias Keplinger, Artem Krasnobaev, John K Berg, Christoph Willa, Ingo Burgert
Lignocellulosic biomass represents the only renewable carbon resource which is available in sufficient amounts to be considered as an alternative for our fossil-based carbon economy. However, an efficient biochemical conversion of lignocellulosic feedstocks is hindered by the natural recalcitrance of the biomass as a result of a dense network of cellulose, hemicelluloses, and lignin. These polymeric interconnections make a pretreatment of the biomass necessary in order to enhance the susceptibility of the polysaccharides...
July 29, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/30096801/developing-hollow-channel-gold-nanoflowers-as-trimodal-intracellular-nanoprobes
#13
Sunjie Ye, May C Wheeler, James R McLaughlan, Abiral Tamang, Christine P Diggle, Oscar Cespedes, Alex F Markham, P Louise Coletta, Stephen D Evans
Gold nanoparticles-enabled intracellular surface-enhanced Raman spectroscopy (SERS) provides a sensitive and promising technique for single cell analysis. Compared with spherical gold nanoparticles, gold nanoflowers, i.e., flower-shaped gold nanostructures, can produce a stronger SERS signal. Current exploration of gold nanoflowers for intracellular SERS has been considerably limited by the difficulties in preparation, as well as background signal and cytotoxicity arising from the surfactant capping layer. Recently, we have developed a facile and surfactant-free method for fabricating hollow-channel gold nanoflowers (HAuNFs) with great single-particle SERS activity...
August 8, 2018: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/30087373/following-laser-induced-changes-of-plant-phenylpropanoids-by-raman-microscopy
#14
Batirtze Prats-Mateu, Peter Bock, Martina Schroffenegger, José Luis Toca-Herrera, Notburga Gierlinger
Raman microscopy is a powerful imaging technique for biological materials providing information about chemistry in context with microstructure. A 532 nm laser is often used as excitation source, because high spatial resolution and signal intensity can be achieved. The latter can be controlled by laser power and integration time, whereby high power and long times give good signal to noise ratio. However, most biological materials absorb in the VIS range and fluorescence masking the signal or even sample degradation might be hindering...
August 7, 2018: Scientific Reports
https://www.readbyqxmd.com/read/30083018/label-free-molecular-imaging-and-analysis-by-raman-spectroscopy
#15
Yasuaki Kumamoto, Yoshinori Harada, Tetsuro Takamatsu, Hideo Tanaka
Raman scattering of a cell conveys the intrinsic information inherent to chemical structures of biomolecules. The spectroscopy of Raman scattering, or Raman spectroscopy, allows label-free and quantitative molecular sensing of a biological sample in situ without disruption. For the last five decades Raman spectroscopy has been widely utilized in biological research fields. However, it is just within the latest decade that molecular imaging and discrimination of living cells and tissues have become practically available...
June 26, 2018: Acta Histochemica et Cytochemica
https://www.readbyqxmd.com/read/30082908/optical-imaging-of-metabolic-dynamics-in-animals
#16
Lingyan Shi, Chaogu Zheng, Yihui Shen, Zhixing Chen, Edilson S Silveira, Luyuan Zhang, Mian Wei, Chang Liu, Carmen de Sena-Tomas, Kimara Targoff, Wei Min
Direct visualization of metabolic dynamics in living animals with high spatial and temporal resolution is essential to understanding many biological processes. Here we introduce a platform that combines deuterium oxide (D2 O) probing with stimulated Raman scattering (DO-SRS) microscopy to image in situ metabolic activities. Enzymatic incorporation of D2 O-derived deuterium into macromolecules generates carbon-deuterium (C-D) bonds, which track biosynthesis in tissues and can be imaged by SRS in situ. Within the broad vibrational spectra of C-D bonds, we discover lipid-, protein-, and DNA-specific Raman shifts and develop spectral unmixing methods to obtain C-D signals with macromolecular selectivity...
August 6, 2018: Nature Communications
https://www.readbyqxmd.com/read/30082723/cell-type-discrimination-based-on-image-features-of-molecular-component-distribution
#17
Arno Germond, Taro Ichimura, Liang-da Chiu, Katsumasa Fujita, Tomonobu M Watanabe, Hideaki Fujita
Machine learning-based cell classifiers use cell images to automate cell-type discrimination, which is increasingly becoming beneficial in biological studies and biomedical applications. Brightfield or fluorescence images are generally employed as the classifier input variables. We propose to use Raman spectral images and a method to extract features from these spatial patterns and explore the value of this information for cell discrimination. Raman images provide information regarding distribution of chemical compounds of the considered biological entity...
August 6, 2018: Scientific Reports
https://www.readbyqxmd.com/read/30082614/effect-of-annealing-temperature-on-ecd-grown-hexagonal-plane-zinc-oxide
#18
Sukrit Sucharitakul, Rangsan Panyathip, Supab Choopun
Zinc oxide (ZnO) offers a great potential in several applications from sensors to Photovoltaic cells thanks to the material's dependency, to its optical and electrical properties and crystalline structure architypes. Typically, ZnO powder tends to be grown in the form of a wurtzite structure allowing versatility in the phase of material growths; albeit, whereas in this work we introduce an alternative in scalable yet relatively simple 2D hexagonal planed ZnO nanoflakes via the electrochemical deposition of commercially purchased Zn(NO₃)₂ and KCl salts in an electrochemical process...
August 6, 2018: Materials
https://www.readbyqxmd.com/read/30081633/chemically-derived-kirigami-of-wse2
#19
Liang Cai, Melinda J Shearer, Yuzhou Zhao, Zhili Hu, Fan Wang, Yi Zhang, Kevin W Eliceiri, Robert J Hamers, Wensheng Yan, Shiqiang Wei, Ming Tang, Song Jin
Layered metal dichalcogenides have shown intriguing physical phenomena depending on their complex layer stackings and unique architectures. Here, we report novel microscale kirigami structures of multilayered WSe2 formed by a simple chemical vapor deposition and etching method. Scanning electron microscopy and atomic force microscopy reveal the unusual structure features of curved concave edges, panhandles, and saw-tooth corners of these intricate multilayer architectures that result from etching. The structure-symmetry relationship and layer stackings of these WSe2 kirigami were elucidated by second-harmonic generation imaging and micro-Raman spectroscopy...
August 7, 2018: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/30080395/intraoperative-detection-and-eradication-of-residual-microtumors-with-gap-enhanced-raman-tags
#20
Yuanyuan Qiu, Yuqing Zhang, Mingwang Li, Gaoxian Chen, Chenchen Fan, Kai Cui, Jian-Bo Wan, Anpan Han, Jian Ye, Zeyu Xiao
The inability to intraoperatively diagnose and eliminate microscopic residual tumors represents a significant challenge in cancer surgery. These residual microtumors cause lethal recurrence and metastasis. Herein, we show a crucial example of Raman imaging with gap-enhanced Raman tags (GERTs) to serve as a robust platform for intraoperative detection and eradication of residual microscopic foci, which exist in surgical margins, tumor invasion, and multifocal tumor spread. The GERTs feature gap-enhanced gold core-shell nanostructures, with Raman reporters embedding inside the interior gap junction...
August 6, 2018: ACS Nano
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