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NL Asfandiarov AI Fokin VG Lukin EP Nafikova GS Lomakin VS Fal'ko YV Chizhov 《Rapid communications in mass spectrometry : RCM》1999,13(12):1116-1123
A series of anthraquinone (C(14)O(2)H(8)) derivatives has been studied by means of electron capture negative ion mass spectrometry (ECNI-MS), photoelectron spectroscopy (PES), and AM1 quantum chemical calculations. Mean lifetimes of molecular negative ions M(-.) (MNI) have been measured. The mechanism of long-lived MNI formation in the epithermal energy region of incident electrons has been investigated. A simple model of a molecule (a spherical potential well with the repulsive centrifugal term) has been applied for the analysis of the energy dependence of cross sections at the first stage of the electron capture process. It has been shown that a temporary resonance of MNI at the energy approximately 0.5 eV corresponds to a shape resonance with lifetime 1-2.10(-13) s in the f-partial wave (l = 3) of the incident electron. The next resonant state of MNI at the energy approximately 1.7 eV has been associated with the electron excited Feshbach resonance (whose parent state is a triplet npi* transition). In all cases the initial electron state of the MNI relaxes into the ground state by means of a radiationless transition, and the final state of the MNI is a nuclear excited resonance with a lifetime measurable on the mass spectrometry timescale. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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Nanoarchitectured Graphene‐Based Supercapacitors for Next‐Generation Energy‐Storage Applications
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Rahul R. Salunkhe Ying‐Hui Lee Kuo‐Hsin Chang Jing‐Mei Li Patrice Simon Jing Tang Nagy L. Torad Prof. Dr. Chi‐Chang Hu Prof. Dr. Yusuke Yamauchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(43):13838-13852
Tremendous development in the field of portable electronics and hybrid electric vehicles has led to urgent and increasing demand in the field of high‐energy storage devices. In recent years, many research efforts have been made for the development of more efficient energy‐storage devices such as supercapacitors, batteries, and fuel cells. In particular, supercapacitors have great potential to meet the demands of both high energy density and power density in many advanced technologies. For the last half decade, graphene has attracted intense research interest for electrical double‐layer capacitor (EDLC) applications. The unique electronic, thermal, mechanical, and chemical characteristics of graphene, along with the intrinsic benefits of a carbon material, make it a promising candidate for supercapacitor applications. This Review focuses on recent research developments in graphene‐based supercapacitors, including doped graphene, activated graphene, graphene/metal oxide composites, graphene/polymer composites, and graphene‐based asymmetric supercapacitors. The challenges and prospects of graphene‐based supercapacitors are also discussed. 相似文献
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Electric Double‐Layer Capacitors Based on Highly Graphitized Nanoporous Carbons Derived from ZIF‐67
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Nagy L. Torad Rahul R. Salunkhe Yunqi Li Hicham Hamoudi Masataka Imura Prof. Dr. Yoshio Sakka Prof. Dr. Chi‐Chang Hu Prof. Dr. Yusuke Yamauchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(26):7895-7900
Nanoporous carbons (NPCs) have large specific surface areas, good electrical and thermal conductivity, and both chemical and mechanical stability, which facilitate their use in energy storage device applications. In the present study, highly graphitized NPCs are synthesized by one‐step direct carbonization of cobalt‐containing zeolitic imidazolate framework‐67 (ZIF‐67). After chemical etching, the deposited Co content can be completely removed to prepare pure NPCs with high specific surface area, large pore volume, and intrinsic electrical conductivity (high content of sp2‐bonded carbons). A detailed electrochemical study is performed using cyclic voltammetry and galvanostatic charge–discharge measurements. Our NPC is very promising for efficient electrodes for high‐performance supercapacitor applications. A maximum specific capacitance of 238 F g?1 is observed at a scan rate of 20 mV s?1. This value is very high compared to previous works on carbon‐based electric double layer capacitors. 相似文献
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Hu M Reboul J Furukawa S Torad NL Ji Q Srinivasu P Ariga K Kitagawa S Yamauchi Y 《Journal of the American Chemical Society》2012,134(6):2864-2867
Nanoporous carbon (NPC) is prepared by direct carbonization of Al-based porous coordination polymers (Al-PCP). By applying the appropriate carbonization temperature, both high surface area and large pore volume are realized for the first time. Our NPC shows much higher porosity than other carbon materials (such as activated carbons and mesoporous carbons). This new type of carbon material exhibits superior sensing capabilities toward toxic aromatic substances. 相似文献
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Towards Vaporized Molecular Discrimination: A Quartz Crystal Microbalance (QCM) Sensor System Using Cobalt‐Containing Mesoporous Graphitic Carbon
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Jing Tang Dr. Nagy L. Torad Dr. Rahul R. Salunkhe Dr. Jang‐Hee Yoon Dr. Md Shahriar Al Hossain Prof. Shi Xue Dou Prof. Jung Ho Kim Dr. Tatsuo Kimura Prof. Yusuke Yamauchi 《化学:亚洲杂志》2014,9(11):3238-3244
A recent study on nanoporous carbon based materials (J. Am. Chem. Soc. 2012 , 134, 2864) showed that the presence of abundant graphitized sp2 carbon species in the frameworks led to higher affinity for aromatic hydrocarbons than their aliphatic analogues. Herein, improved understanding of the sensitive and selective detection of aromatic substances by using mesoporous carbon (MPC)‐based materials, combined with a quartz crystal microbalance (QCM) sensor system, was obtained. MPCs were synthesized by direct carbonization of mesoporous polymers prepared from resol through a soft templating approach with Pluronic F127. The carbon‐based frameworks can be graphitized through the addition of a cobalt source to the precursor solution, according to the catalytic activity of the cobalt nanoparticles formed during the carbonization process. From the Raman data, the degree of the graphitization was clearly increased by increasing the cobalt content and elevating the carbonization temperature. From a QCM study, it was proved that the highly graphitized MPCs exhibited a higher affinity for aromatic hydrocarbons than their aliphatic analogues. By increasing the degree of graphitization in the carbon‐based pore walls, the MPCs showed both larger adsorption uptake and faster sensor response towards toxic benzene and toluene vapors. 相似文献
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Optimal design of coastal or offshore structures requires the estimation of extreme quantiles of oceanographic data such as wave heights and wave periods. Since there are strong correlations between oceanographic variables, it is necessary to use multivariate models in order to capture its dependencies. To achieve this, an approach based on copulas is proposed and is compared to a model based on the physical behaviour of waves. 相似文献
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Dual Soft‐Template System Based on Colloidal Chemistry for the Synthesis of Hollow Mesoporous Silica Nanoparticles
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Yunqi Li Dr. Bishnu Prasad Bastakoti Dr. Masataka Imura Jing Tang Prof. Ali Aldalbahi Dr. Nagy L. Torad Prof. Yusuke Yamauchi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(17):6375-6380
A new dual soft‐template system comprising the asymmetric triblock copolymer poly(styrene‐b‐2‐vinyl pyridine‐b‐ethylene oxide) (PS‐b‐P2VP‐b‐PEO) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) is used to synthesize hollow mesoporous silica (HMS) nanoparticles with a center void of around 17 nm. The stable PS‐b‐P2VP‐b‐PEO polymeric micelle serves as a template to form the hollow interior, while the CTAB surfactant serves as a template to form mesopores in the shells. The P2VP blocks on the polymeric micelles can interact with positively charged CTA+ ions via negatively charged hydrolyzed silica species. Thus, dual soft‐templates clearly have different roles for the preparation of the HMS nanoparticles. Interestingly, the thicknesses of the mesoporous shell are tunable by varying the amounts of TEOS and CTAB. This study provides new insight on the preparation of mesoporous materials based on colloidal chemistry. 相似文献
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Highly Crystallized Nanometer‐Sized Zeolite A with Large Cs Adsorption Capability for the Decontamination of Water
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Nagy L. Torad Dr. Masanobu Naito Dr. Junichi Tatami Dr. Akira Endo Sin‐Yen Leo Dr. Shinsuke Ishihara Dr. Kevin C.‐W. Wu Dr. Toru Wakihara Dr. Yusuke Yamauchi 《化学:亚洲杂志》2014,9(3):759-763
Nanometer‐sized zeolite A with a large cesium (Cs) uptake capability is prepared through a simple post‐milling recrystallization method. This method is suitable for producing nanometer‐sized zeolite in large scale, as additional organic compounds are not needed to control zeolite nucleation and crystal growth. Herein, we perform a quartz crystal microbalance (QCM) study to evaluate the uptake ability of Cs ions by zeolite, to the best of our knowledge, for the first time. In comparison to micrometer‐sized zeolite A, nanometer‐sized zeolite A can rapidly accommodate a larger amount of Cs ions into the zeolite crystal structure, owing to its high external surface area. Nanometer‐sized zeolite is a promising candidate for the removal of radioactive Cs ions from polluted water. Our QCM study on Cs adsorption uptake behavior provides the information of adsorption kinetics (e.g., adsorption amounts and rates). This technique is applicable to other zeolites, which will be highly valuable for further consideration of radioactive Cs removal in the future. 相似文献