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https://www.readbyqxmd.com/read/29140802/characterization-with-scanning-electron-microscopy-energy-dispersive-x-ray-spectrometry-of-microtraces-from-the-ligature-mean-in-hanging-mechanical-asphyxia-a-series-of-forensic-cases
#1
Francesca Maghin, Salvatore Ambrogio Andreola, Michele Boracchi, Guendalina Gentile, Francesca Maciocco, Riccardo Zoja
The authors applied scanning electron microscopy with energy-dispersive x-ray spectrometry to the furrow derived from hanging means. The study was conducted with the purpose to detect possible extraneous microtraces, deriving from the ligature, that could have had an interaction with the cutaneous biological matrix, thanks to a transfert mechanism, in the proximities of the lesion.Fifteen cutaneous samples of the furrow and an equal number of fragments of graphite tape, directly positioned on the lesion produced by the ligature mean and used as a "conductor" of possible traces, were analyzed using scanning electron microscopy with energy-dispersive x-ray spectrometry...
November 15, 2017: American Journal of Forensic Medicine and Pathology
https://www.readbyqxmd.com/read/29139500/self-assembly-of-wo3-3-clusters-on-a-highly-oriented-pyrolytic-graphite-surface-and-nanowire-formation-a-combined-experimental-and-theoretical-study
#2
Xin Tang, Kit H Bowen, Florent Calvo
Tungsten oxide cluster anions (WO3)3(-) produced from a magnetron source were soft-landed on highly oriented pyrolytic graphite (HOPG) surfaces at different temperatures, and the structures formed upon deposition were analyzed using ex situ atomic force microscopy. Under liquid nitrogen cooling conditions of 100 K, the clusters form small branched nanostructures extending over a few nanometers with a height not exceeding 1 nm. At 673 K, nanowires approximately 100 nm long and less than 10 nm in diameter are observed...
November 15, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29138773/cooperating-dipole-dipole-and-van-der-waals-interactions-driven-2d-self-assembly-of-fluorenone-derivatives-ester-chain-length-effect
#3
Meiqiu Dong, Kai Miao, Yi Hu, Juntian Wu, Jinxing Li, Peng Pang, Xinrui Miao, Wenli Deng
Two-dimensional supramolecular assemblies of a series of 2,7-bis(10-n-alkoxycarbonyl-decyloxy)-9-fluorenone derivatives (BAF-Cn, n = 1, 3-6) consisting of polar fluorenone moieties and ester alkoxy chains were investigated by scanning tunneling microscopy on highly oriented pyrolytic graphite surfaces. The chain-length effect was observed in the self-assembly of BAF-Cn. Self-assembly of BAF-C1 was composed of a linear I pattern, where the side chains adopted a fully interdigitated arrangement. As the length of side chains increased, the coexistence of a linear I pattern and a cyclic pattern for the self-assembly of BAF-C3 was observed...
November 15, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29137797/fabrication-of-g-c3n4-nio-heterostructured-nanocomposite-modified-glassy-carbon-electrode-for-quercetin-biosensor
#4
S Selvarajan, A Suganthi, M Rajarajan
Herein, we report a one-pot synthesis of structurally uniform and electrochemically active graphitic carbon nitride/nickel oxide (g-C3N4/NiO) nanocomposite and an investigation on the electrocatalytic oxidation of quercetin (QR). The synthesized g-C3N4/NiO nanocomposite has uniform surface distribution, which was characterized with scanning electron microscopy (SEM). Moreover, the composition of synthesized g-C3N4/NiO nanocomposite was characterized by UV-vis-spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR spectra), BET, SEM and HRTEM...
March 2018: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/29137742/ultrasound-coupled-with-supercritical-carbon-dioxide-for-exfoliation-of-graphene-simulation-and-experiment
#5
Yanzhe Gai, Wucong Wang, Ding Xiao, Yaping Zhao
Ultrasound coupled with supercritical CO2 has become an important method for exfoliation of graphene, but behind which a peeling mechanism is unclear. In this work, CFD simulation and experiment were both investigated to elucidate the mechanism and the effects of the process parameters on the exfoliation yield. The experiments and the CFD simulation were conducted under pressure ranging from 8MPa to 16MPa, the ultrasonic power ranging from 12W to 240W and the frequency of 20kHz. The numerical analysis of fluid flow patterns and pressure distributions revealed that the fluid shear stress and the periodical pressure fluctuation generated by ultrasound were primary factors in exfoliating graphene...
March 2018: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/29137704/high-throughput-screening-of-phenoxy-carboxylic-acids-with-dispersive-solid-phase-extraction-followed-by-direct-analysis-in-real-time-mass-spectrometry
#6
Jiaqin Wang, Jun Zhu, Ling Si, Qi Du, Hongli Li, Wentao Bi, David Da Yong Chen
A high throughput, low environmental impact methodology for rapid determination of phenoxy carboxylic acids (PCAs) in water samples was developed by combing dispersive solid phase extraction (DSPE) using velvet-like graphitic carbon nitride (V-g-C3N4) and direct analysis in real time mass spectrometry (DART-MS). Due to the large surface area and good dispersity of V-g-C3N4, the DSPE of PCAs in water was completed within 20 s, and the elution of PCAs was accomplished in 20 s as well using methanol. The eluents were then analyzed and quantified using DART ionization source coupled to a high resolution mass spectrometer, where an internal standard was added in the samples...
December 15, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29137456/highly-stretchable-conductors-based-on-expanded-graphite-macro-confined-in-tubular-rubber
#7
Wei Luo, Tongfei Wu, Biqiong Chen, Mei Liang, Huawei Zou
Highly stretchable and durable conductors are significant to the development of wearable devices, robots, human-machine interfaces and other artificial intelligence products. Although many respectable methods have been reported, it is still a challenge to fabricate stretchable conductors with a large elastic limit, high conductivity and excellent reliability in rapid, effective and economic ways. Herein, a facile method is offered to fabricate high-performance stretchable tubular conductors (TCs) based on a macro-confined structure of expanded graphite (EG) in rubber tubing by simply physical packing...
November 15, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29136880/enhanced-electrochemical-response-of-carbon-quantum-dot-modified-electrodes
#8
M Algarra, A González-Calabuig, K Radotić, D Mutavdzic, C O Ania, J M Lázaro-Martínez, J Jiménez-Jiménez, E Rodríguez-Castellón, M Del Valle
A glassy carbon electrode (GCE) was surface-modified with carbon quantum dots (CQDs) and applied for the effective enhancement of the electrochemical signal for dopamine and uric acid determination. CQDs were prepared from graphite by a green modification of the Hummers method. They were characterized by FTIR-ATR, XPS, solid-state NMR, fluorescence and Raman spectroscopies. TPD-MS analysis was applied to characterize the functionalization of the surface. The CQDs were assembled on the glassy carbon electrode by adsorption because of the large number of carboxy groups on their surface warrants effective adsorption...
February 1, 2018: Talanta
https://www.readbyqxmd.com/read/29136838/a-robotic-magnetic-nanoparticle-solid-phase-extraction-system-coupled-to-flow-batch-analyzer-and-gfaas-for-determination-of-trace-cadmium-in-edible-oils-without-external-pretreatment
#9
Inakã S Barreto, Stefani I E Andrade, Francisco A S Cunha, Marcelo B Lima, Mario Cesar U Araujo, Luciano F Almeida
A lab-made magnetic-mechanical robotic (MMR) system coupled to a flow-batch analyzer (FBA) for magnetic nanoparticles solid phase extraction (MSPE) is presented. As an illustrative application, an NMR-FBA couple was connected to a graphite furnace atomic absorption spectrometer (GFAAS) for quantification of trace cadmium in edible oils. Factors affecting MSPE, such as the amount of adsorbent, the type, concentration and volume of the eluent and elution time were studied. Under the optimized experimental conditions, the interferents studied did not reveal a significant change in the analytical response, indicating that proposed method is selective...
February 1, 2018: Talanta
https://www.readbyqxmd.com/read/29136792/comparative-performances-of-a-bare-graphite-polyurethane-composite-electrode-unmodified-and-modified-with-graphene-and-carbon-nanotubes-in-the-electrochemical-determination-of-escitalopram
#10
Marina Baccarin, Priscila Cervini, Eder Tadeu Gomes Cavalheiro
A bare composite graphite-polyurethane electrode (EGPU) and two other modified with graphene (EGPU-GR) and functionalized multi-walled carbon nanotubes (EGPU-CNTs) were prepared and compared regarding their voltammetric response to escitalopran (EST). The modifiers were characterized by Raman spectroscopy and the resulting electrode materials by contact angle measurements with a hydrophilicity character in the ascending order for the composites: GPU > GPU-GR > GPU-CNTs and scanning electron microscopy (SEM)...
February 1, 2018: Talanta
https://www.readbyqxmd.com/read/29136460/graphitic-nitrogen-triggers-red-fluorescence-in-carbon-dots
#11
Katerina Hola, Mária Sudolská, Sergii Kalytchuk, Dana Nachtigallova, Andrey L Rogach, Michal Otyepka, Radek Zbořil
Carbon dots (CDs) are a stable and highly biocompatible fluorescent material offering great application potential in cell labeling, optical imaging, LED diodes, and optoelectronic technologies. Because their emission wavelengths provide the best tissue penetration, red-emitting CDs are of a particular interest for applications in biomedical technologies. Current synthetic strategies enabling red-shifted emission include increasing the CD particle size (sp2 domain) by a proper synthetic strategy and tuning the surface chemistry of CDs with suitable functional groups (e...
November 14, 2017: ACS Nano
https://www.readbyqxmd.com/read/29134802/ab-initio-study-of-interfacial-structure-transformation-of-amorphous-carbon-catalyzed-by-ti-cr-and-w-transition-layers
#12
Xiaowei Li, Lei Li, Dong Zhang, Aiying Wang
Amorphous carbon (a-C) films composited with transition layers exhibit the desirable improvement of adhesion strength between films and substrate, but the further understanding on the interfacial structure transformation of a-C structure induced by transition layers is still lacked. In this paper, using ab initio calculations, we comparatively studied the interfacial structure between Ti, Cr or W transition layers and a-C film from the atomic scale, and demonstrated that the addition of Ti, Cr or W catalyzed the graphitic transformation of a-C structure at different levels, which provided the theoretical guidance for designing multilayer nanocomposite film for renewed application...
November 14, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29134768/determination-of-multiple-antibiotics-in-leafy-vegetables-using-quechers-uhplc-ms-ms
#13
Xiaolu Yu, Hang Liu, Chengjun Pu, Junhao Chen, Ying Sun, Lin Hu
A modified quick, easy, cheap, effective, rugged and safe method was established for simultaneous extraction and cleanup of multiple antibiotics in leafy vegetables, and ultra high performance liquid chromatography with tandem mass spectrometry was used for analysis. Antibiotics in leafy vegetables were extracted with citric acid/sodium citrate in mixed solvents consisting of acetonitrile/methanol (85:15 v/v) from 10 g of vegetables. Octadecylsilyl and graphitized carbon black were used as dispersant adsorbents...
November 14, 2017: Journal of Separation Science
https://www.readbyqxmd.com/read/29132011/effect-of-anode-polarization-on-biofilm-formation-and-electron-transfer-in-shewanella-oneidensis-graphite-felt-microbial-fuel-cells
#14
David Pinto, Thibaud Coradin, Christel Laberty-Robert
In microbial fuel cells, electricity generation is assumed by bacterial degradation of low-grade organics generating electrons that are transferred to an electrode. The nature and efficiency of the electron transfer from the bacteria to the electrodes are determined by several chemical, physical and biological parameters. Specifically, the application of a specific potential at the bioanode has been shown to stimulate the formation of an electro-active biofilm, but the underlying mechanisms remain poorly understood...
October 31, 2017: Bioelectrochemistry
https://www.readbyqxmd.com/read/29131994/ph-dependent-kow-provides-new-insights-in-understanding-the-adsorption-mechanism-of-ionizable-organic-chemicals-on-carbonaceous-materials
#15
Hao Li, Yanbei Cao, Di Zhang, Bo Pan
The dominant adsorption mechanism of ionizable organic chemicals (IOCs) on carbonaceous materials is still unclear. This study used benzoic acid (BA), o-chlorobenzoic acid (2-CBA) and p-chlorobenzoic acid (4-CBA) as representatives of IOCs to investigate the dominant adsorption mechanism on graphene oxide (GO) and graphite (GP), with a specific emphasis on the impact of pH-dependent KOW. The order of apparent adsorption of the investigated chemicals changed with pH, which could not be explained by their constant KOW...
November 10, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/29131962/intercalation-and-deintercalation-of-lithium-at-the-ionic-liquid-graphite-0001-interface
#16
Florian Buchner, Jihyun Kim, Christiane Adler, Maral Bozorgchenani, Joachim Bansmann, R Jürgen Behm
The intercalation and deintercalation of lithium (Li) into / out of graphite(0001), which is a highly important process in Li-ion batteries, was investigated under ultrahigh vacuum conditions as a function of temperature, employing X-ray and ultraviolet photoelectron spectroscopy. Both the up-shifts of the core-level binding energy and the lowering of the work function ΔΦ reveal that heating of a monolayer of the battery-relevant ionic liquid (IL) 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide ([BMP](+)[TFSI](-)) adsorbed on lithiated graphite at 80 K to >230 K facilitates an accumulation of partially charged Li(δ+) atoms at the IL-graphite(0001) interface...
November 15, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/29131939/concentration-directed-polymorphic-surface-covalent-organic-frameworks-rhombus-parallelogram-and-kagome
#17
Yi-Ping Mo, Xuan-He Liu, Dong Wang
Polymorphic single-layered covalent organic frameworks (sCOFs) via on-surface synthesis have been investigated by employing the tetradentate monomer 1,3,6,8-tetrakis(p-formylphenyl)pyrene with D2h symmetry and ditopic linear diamine building blocks. Three kinds of well-ordered sCOFs, including rhombus, parallelogram, and Kagome networks, are observed on the graphite surface by scanning tunnel microscopy. The pore size and periodicity of sCOFs are tunable by employing diamine monomers with different lengths...
November 15, 2017: ACS Nano
https://www.readbyqxmd.com/read/29131607/carbon-papers-and-aerogels-based-on-graphene-layers-and-chitosan-direct-preparation-from-high-surface-area-graphite
#18
Vincenzina Barbera, Silvia Guerra, Luigi Brambilla, Mario Maggio, Andrea Serafini, Lucia Conzatti, Alessandra Vitale, Maurizio Galimberti
In this work, carbon papers and aerogels based on graphene layers and chitosan were prepared. They were obtained by mixing chitosan (CS) and a high surface area nanosized graphite (HSAG) in water in the presence of acetic acid. HSAG/CS water dispersions were stable for months. High resolution transmission electron microscopy revealed the presence of few graphene layers in water suspensions. Casting or lyophilization of such suspensions led to the preparation of carbon paper and aerogel respectively. In X-ray spectra of both aerogels and carbon paper, peaks due to regular stacks of graphene layers were not detected: graphene with unaltered sp(2) structure was obtained directly from graphite without the use of any chemical reaction...
November 13, 2017: Biomacromolecules
https://www.readbyqxmd.com/read/29131344/aerrow-a-probe-format-graphite-calorimeter-for-absolute-dosimetry-of-high-energy-photon-beams-in-the-clinical-environment
#19
James Renaud, Arman Sarfehnia, Julien Bancheri, Jan Seuntjens
In this work, the design, operation, initial experimental evaluation, and characterization of a small-scale graphite calorimeter probe - herein referred to as the Aerrow - developed for routine use in the clinical environment, is described. Similar in size and shape to a Farmer type cylindrical ionization chamber, the Aerrow represents the first translation of calorimetry intended for direct use by clinical physicists in the radiotherapy clinic METHODS: Based on a numerically-optimized design obtained in previous work, a functioning Aerrow prototype capable of two independent modes of operation (quasi-adiabatic and isothermal) was constructed in-house...
November 13, 2017: Medical Physics
https://www.readbyqxmd.com/read/29131343/extracting-wair-from-the-electron-beam-measurements-of-domen-and-lamperti
#20
Frédéric Tessier, Claudiu Dorin Cojocaru, Carl Kenneth Ross
PURPOSE: The average energy expended by an energetic electron to create an ion pair in dry air, Wair, is a key quantity in radiation dosimetry. Although Wair is well established for electron energies up to about 3 MeV there is limited data for higher energies. The measurements by Domen and Lamperti [Med. Phys. 3, 294{301 (1976)] using electron beams in the energy range from 15 to 50 MeV can, in principle, be used to deduce values for Wair, if the electron stopping power of graphite and air are known...
November 13, 2017: Medical Physics
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