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Zachary R Dunbar, Ananth Das, Richard J O'Connor, Maciej L Goniewicz, Binnian Wei, Mark J Travers
Few published studies have investigated the presence of lead in the e-liquid of electronic nicotine delivery systems (ENDS). Lead inhalation is associated with increased risk of stroke, heart disease, and other diseases. This study used a novel application of graphite furnace technology to compare the concentration of lead between e-liquids of different packaging and product designs using e-liquids that are or were commercially available in the United States and Canada. Eleven nicotine-free disposable ENDS devices and 12 bottled refill solutions that contained nicotine were purchased from retailers in Canada and the United States between 2015 and 2017...
January 19, 2018: International Journal of Environmental Research and Public Health
Bin Wang, Jaegeon Ryu, Sungho Choi, Gyujin Song, Dongki Hong, Chihyun Hwang, Xiong Chen, Bo Wang, Wei Li, Hyun-Kon Song, Soojin Park, Rodney S Ruoff
We show that a high energy density can be achieved in a practical manner with freestanding electrodes without using conductive carbon, binders, and current collectors. We made and used a folded graphene composite electrode designed for a high areal capacity anode. The traditional thick graphene composite electrode, such as made by filtering graphene oxide to create a thin film and reducing it such as through chemical or thermal methods, has sluggish reaction kinetics. Instead, we have made and tested a thin composite film electrode that was folded several times using a water-assisted method; it provides a continuous electron transport path in the fold regions and introduces more channels between the folded layers, which significantly enhances the electron/ion transport kinetics...
January 19, 2018: ACS Nano
Mingdao Zhang, Quanbin Dai, Hegen Zheng, Mindong Chen, Liming Dai
Metal-organic frameworks (MOFs) and MOF-derived materials have recently attracted considerable interest as alternatives to noble-metal electrocatalysts. Herein, the rational design and synthesis of a new class of Co@N-C materials (C-MOF-C2-T) from a pair of enantiotopic chiral 3D MOFs by pyrolysis at temperature T is reported. The newly developed C-MOF-C2-900 with a unique 3D hierarchical rodlike structure, consisting of homogeneously distributed cobalt nanoparticles encapsulated by partially graphitized N-doped carbon rings along the rod length, exhibits higher electrocatalytic activities for oxygen reduction and oxygen evolution reactions (ORR and OER) than that of commercial Pt/C and RuO2 , respectively...
January 19, 2018: Advanced Materials
Ş Ortatatlı, J Knossalla, F Schüth, C Weidenthaler
This article aims to address the formation and the structural disordering/ordering phenomena of PtNi nanoalloys supported on hollow graphitic spheres (HGSs) using pair distribution function (PDF) analysis under ex situ/in situ data collection conditions. Starting from small nanoparticles (10-15 Å in diameter) embedded in HGSs, structural changes were monitored during stepwise heating and cooling of the sample using in situ PDF analysis. In order to evaluate the conventional synthesis route for the production of PtNi nanoalloys supported on HGSs, ex situ PDF experiments were performed before and after heat treatment in a furnace...
January 19, 2018: Physical Chemistry Chemical Physics: PCCP
Yixian Wang, Wei Tian, Luhai Wang, Haoran Zhang, Jialiang Liu, Tingyue Peng, Lei Pan, Xiaobo Wang, Mingbo Wu
Amorphous carbon is regarded as a promising alternative to commercial graphite as the lithium-ion battery anode due to its capability to reversibly store more lithium ions. However, the structural disorder with a large number of defects can lead to low electrical conductivity of the amorphous carbon, thus limiting its application for high power output. Herein, ultrathin amorphous carbon nanosheets were prepared from petroleum asphalt through tuning the carbonization temperature in a molten-salt medium. The amorphous nanostructure with expanded carbon interlayer spacing can provide substantial active sites for lithium storage while the two-dimensional (2D) morphology can facilitate fast electrical conductivity...
January 18, 2018: ACS Applied Materials & Interfaces
Qi-Jun Sun, Jiaqing Zhuang, Shishir Venkatesh, Ye Zhou, Su-Ting Han, Wei Wu, Ka-Wai Kong, Wen-Jung Li, Xianfeng Chen, Robert K Y Li, Vellaisamy A L Roy
Piezoresistive microsensors are considered to be essential components of the future wearable electronic devices. However, the expensive cost, complex fabrication technology, poor stability, and low yield have limited their developments for practical applications. Here, we present a cost-effective, relatively simple, and high-yield fabrication approach to construct highly sensitive and ultrastable piezoresistive sensors using a bioinspired hierarchically structured graphite/polydimethylsiloxane composite as the active layer...
January 18, 2018: ACS Applied Materials & Interfaces
Paul O Phelps, J Andrew Carlson, Dale R Meyer
The authors present a case of a gradually enlarging pigmented mass of the upper eyelid and anterior orbit that was discovered to be the graphite tip of a pencil surrounded by macrophages bearing graphite and fibrous tissue. A 25-year-old woman with no medical history presented with a gradually enlarging pigmented lesion of her left upper eyelid. She denied any history of previous skin cancer, trauma, or previous surgery. A biopsy was performed. This revealed an encapsulated grayish, pigmented mass within the medial portion of the left upper eyelid and anterior orbit...
November 2017: Ocular Oncology and Pathology
Xuefeng Zhang, Qiangu Yan, Jinghao Li, Jilei Zhang, Zhiyong Cai
Effects of physical and chemical states of iron-based catalysts on the formation of carbon-encapsulated iron nanoparticles (CEINs) synthesized thermally from kraft lignin were investigated. Experimental results indicated that if solution-based iron nitrate (FeN) was used as an iron source for the catalyst, CEINs observed were α-Fe and γ-Fe-based cores encapsulated by few layers graphitic-carbon (mostly 1-5 layers) and the majority of these CEINs were embedded in amorphous carbon matrix. The formation of graphitic-carbon shells is believed based on the dissolution and precipitation mechanism of amorphous carbon acting as the carbon source...
January 15, 2018: Materials
Andreu González-Calabuig, Xavier Cetó, Manel Del Valle
This work reports the applicability of a voltammetric sensor array able to quantify the content of 2,4-dinitrophenol, 4-nitrophenol, and picric acid in artificial samples using the electronic tongue (ET) principles. The ET is based on cyclic voltammetry signals, obtained from an array of metal disk electrodes and a graphite epoxy composite electrode, compressed using discrete wavelet transform with chemometric tools such as artificial neural networks (ANNs). ANNs were employed to build the quantitative prediction model...
January 13, 2018: Sensors
Shuai Zhang, Chen-Guang Wang, Ming-Yang Li, Di Huang, Lain-Jong Li, Wei Ji, Shiwei Wu
The atomic and electronic structure of intrinsic defects in a WSe_{2} monolayer grown on graphite was revealed by low temperature scanning tunneling microscopy and spectroscopy. Instead of chalcogen vacancies that prevail in other transition metal dichalcogenide materials, intrinsic defects in WSe_{2} arise surprisingly from single tungsten vacancies, leading to the hole (p-type) doping. Furthermore, we found these defects to dominate the excitonic emission of the WSe_{2} monolayer at low temperature. Our work provided the first atomic-scale understanding of defect excitons and paved the way toward deciphering the defect structure of single quantum emitters previously discovered in the WSe_{2} monolayer...
July 28, 2017: Physical Review Letters
F Arnold, A Isidori, E Kampert, B Yager, M Eschrig, J Saunders
Graphite is a model system for the study of three-dimensional electrons and holes in the magnetic quantum limit, in which the charges are confined to the lowest Landau levels. We report magneto-transport measurements in pulsed magnetic fields up to 60 T, which resolve the collapse of two charge density wave states in two, electron and hole, Landau levels at 52.3 and 54.2 T, respectively. We report evidence for a commensurate charge density wave at 47.1 T in the electron Landau level, and discuss the likely nature of the density wave instabilities over the full field range...
September 29, 2017: Physical Review Letters
Tyson C Davis, Jae Jin Bang, Jacob T Brooks, David G McMillan, Shelley A Claridge
Noncovalent monolayer chemistries are often used to functionalize 2D materials. Nanoscopic ligand ordering has been widely demonstrated (e.g., lying-down lamellar phases of functional alkanes); however, combining this control with micro- and macroscopic patterning for practical applications remains a significant challenge. A few reports have demonstrated that standing phase Langmuir films on water can be converted into nanoscopic lying-down molecular domains on 2D substrates (e.g., graphite), using horizontal dipping (Langmuir-Schaefer, LS, transfer)...
January 17, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Arathi P J, Seemesh Bhaskar, Rajendra Kumar Reddy G, Suresh Kumar P, Ramanathan V
We report on the ability of template-electrodeposited copper on pencil graphite as a novel and cost effective photocatalyst by considering the photodimerization of p-aminothiophenol (p-ATP) to 4,4'-dimercaptoazobenzene.
January 17, 2018: Physical Chemistry Chemical Physics: PCCP
Xian-Zhu Deng, Chuang Song, Yin-Lin Tong, Guoliang Yuan, Feng Gao, Dan-Qing Liu, Shan-Tao Zhang
As one of the most promising photocatalysts, graphitic carbon nitride (g-C3N4) shows a visible light response and great chemical stability. However, its relatively low photocatalytic efficiency is a major obstacle to actual applications. Here an effective and feasible method to dramatically increase the visible light photocatalytic efficiency by forming C3N4/BiFeO3 ferroelectric heterojunctions is reported, wherein the band alignment and piezo-/ferroelectricity have synergistic positive effects in accelerating the separation of the photogenerated carriers...
January 17, 2018: Physical Chemistry Chemical Physics: PCCP
Vladimir Blank, Valentin Churkin, Boris Kulnitskiy, Igor A Perezhogin, Alexey Kirichenko, Viktor Denisov, Sergey Erohin, Pavel Sorokin, Mikhail Popov
Phase diagrams of carbon, and those focusing on the graphite-to-diamond transitional conditions in particular, are of great interest for fundamental and applied research. The present study introduces a number of experiments carried out to convert graphite under high-pressure conditions, showing a formation of stable phase of fullerene-type onions cross-linked by sp3-bonds in the 55-115 GPa pressure range instead of diamonds formation (even at temperature 2000-3000 K) and the already formed diamonds turn into carbon onions...
January 17, 2018: Nanotechnology
Huitian Liu, Zhongqiang Shan, Wenlong Huang, Dongdong Wang, Zejing Lin, Zongjie Cao, Peng Chen, Shuxian Meng, Li Chen
The utilization of silicon/carbon composites as anode materials to replace the commercial graphite is hampered by their tendency to huge volumetric expansion, costly raw materials, and complex synthesis processes in lithium-ion batteries. Herein, self-assembly method is successfully applied to prepare hierarchical silicon nanoparticles@oxidized mesocarbon microbeads/carbon (Si@O-MCMB/C) composites for the first time, in which O-MCMB core and low-cost sucrose-derived carbon shell not only effectively enhance the electrical conductivity of the anode, but also mediate the dramatic volume change of silicon during cycles...
January 16, 2018: ACS Applied Materials & Interfaces
Yan Wu, Hou Wang, Wenguang Tu, Yue Liu, Yong Zen Tan, Xingzhong Yuan, Jia Wei Chew
Materials of perovskite-type structure have attracted considerable attention for their applications in photocatalysis. In this study, a novel composite of p-type LaFeO3 microsphere coated with n-type nanosized graphitic carbon nitride nanosheets was constructed by the quasi-polymeric calcination method with the aid of electrostatic self-assembly interaction. Results indicate that the LaFeO3/g-C3N4p-n heterostructured photocatalyst obtained, in contrast to the pure constituents, enabled improved visible-light absorption, and more efficient separation and migration of charge carriers via solid p-n heterojunction interfacial effect...
January 11, 2018: Journal of Hazardous Materials
Alexander D Warren, David J Mitchell, Paul J Gates
There is still a need to develop reliable and robust matrix deposition methods for matrix-assisted laser desorption/ionisation mass spectrometry that are applicable to a range of matrices, solvents and analyte types. This paper presents a robust methodology for the airbrush application of matrices along with the implications of varying the set-up and airbrush parameters. A small number of organic analytes and metal salts are analysed in both positive and negative ion modes to exemplify this methodology. In the analyses with the airbrush deposited matrices, performance was enhanced when compared to standard pipette deposition with the need for a search for sweat spots greatly diminished due to the increase homogeneity of the matrix surface and resultant analyte spots...
February 2018: European Journal of Mass Spectrometry
Viktor Brus, Marc A Gluba, Joerg Rappich, Felix Lang, Zakhar Kovalyuk, Pavlo Maryanchuk, Norbert H Nickel
A detailed study of hitherto unknown electrical and thermoelectric properties of graphite pencil traces on paper was carried out by measuring the Hall and Seebeck effects. We show that the combination of pencil-drawn graphite and brush-painted PEDOT:PSS films on regular office paper results in extremely simple, low-cost and environmentally friendly thermoelectric power generators with promising output characteristics at low-temperature gradients. The working characteristics can be improved even further by incorporating n-type InSe flakes...
January 16, 2018: ACS Applied Materials & Interfaces
Lin Liu, Ya-Xia Yin, Jin-Yi Li, Shu-Hua Wang, Yu-Guo Guo, Li-Jun Wan
The lithium metal anode has attracted soaring attention as an ideal battery anode. Unfortunately, nonuniform Li nucleation results in uncontrollable growth of dendritic Li, which incurs serious safety issues and poor electrochemical performance, hindering its practical applications. Herein, this study shows that uniform Li nucleation/growth can be induced by an ultralight 3D current collector consisting of in situ nitrogen-doped graphitic carbon foams (NGCFs) to realize suppressing dendritic Li growth at the nucleating stage...
January 15, 2018: Advanced Materials
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