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Ren, X.Y.,Zhao, C.X.,Niu, C.Y.,Wang, J.Q.,Jia, Y.,Cho, J.H. North-Holland 2016 Physics letters. Section A. Vol.380 No.46
<P>As the analog of carbon allotropes, new three-dimensional (3D) boron nitride (BN) allotropes have attracted much attention of researchers due to their great importance in fundamental sciences and wide practical applications. Here, based on first-principles density-functional theory calculations, we predict two new stable BN allotropes: One is H-18-BN with the P (6) over bar m2 (D-3h(1)) symmetry containing eighteen atoms in the hexagonal unit cell and the other is Rh6-BN with the R (3) over barm (C-3v(5)) symmetry containing six atoms in the rhombohedral primitive unit cell. The dynamic stabilities of the two structures are examined through the phonon spectrum analysis as well as molecular dynamics simulations, whereas the mechanical properties are analyzed by elastic constants, bulk modulus and shear modulus. From the analysis of the enthalpy evolution with respect to pressure, we find that h-BN can be transformed into either H-18-BN or RH6-BN structure under a higher pressure of similar to 15 GPa. We also find that both the H-18-BN and Rh6-BN allotropes are brittle materials with indirect band gaps of 2.31 and 4.48 eV, respectively. The simulated XRD spectra provide detailed structural information of H-18-BN and Rh6-BN for future experimental examinations. Our findings not only greatly enrich the existing structural family of 3D-BN materials but also stimulate further experiments. (C) 2016 Elsevier B.V. All rights reserved.</P>
China Spallation Neutron Source: Accelerator Design Iterations and R&D Status
J. Wei,C.-D. Deng,C.-H. Wang,C.-T. Shi,H. Sun,H.-F. Ouyang,H.-M. Qu,H.-Y. Dong,J. Li,J. Zhang,J.-S. Cao,J.-Y. Tang,L. Dong,L.-L. Wang,Q. Qin,Q.-B. Wang,S. Wang,S.-N. Fu,S.-X Fang,T. -G. Xu,W. Kang,Y.- 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.I
The China Spallation Neutron Source (CSNS) is a high-power, accelerator-based project currently under preparation. The accelerator complex consists of an H$^-$ ion source, an H$^-$ linac, a rapid-cycling proton synchrotron, and the transport lines. During the past year, the design of most accelerator systems went through major iterations, and initial research and developments was started on the prototyping of several key components.
X. J. Chen,J. C. Xu,H. X. Jin,D. F. Jin,B. Hong,H. L. Ge,X. Q. Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.5
In this paper, ordered mesoporous SBA-15 silica was synthesized by the hydrothermal method, and then a series of CoFe2O4/SBA-15 nanocomposites were synthesized by a facile impregnation method. X-ray diffraction and N2 adsorption–desorption isotherms were used to characterize the microstructure and morphology of SBA-15 and CoFe2O4/SBA-15 nanocomposites. CoFe2O4 nanoparticles presented spinel phase structure and existed in the mesopores of SBA-15. The magnetic response of CoFe2O4/SBA-15 nanocomposites was characterized with vibrating sample magnetometer (VSM). The adsorption efficiency of CoFe2O4/SBA-15 nanocomposites for methylene blue increased firstly with the increasing CoFe2O4 content, and then decreased. Sample-2 (SBA-15: CoFe2O4 = 1: 0.1 in the precursor) not only presented the best adsorptive performance, but also could be separated and retrieved effectively by magnetic separation technique.
X. Y. Le,S. Yan,W. J. Zhao,B. H. Han,Y. G. Wang,J. M. Xue,H. T. Zhang 한국진공학회(ASCT) 2002 Journal of Korean Vacuum Science & Technology Vol.6 No.2
In this paper, we treated the Ni₃Al based alloy samples with intense pulsed ion beams (IPIB) at the beam parameters of 250KV acceleration voltage, 100 - 200 A/㎤ current density and 60 ㎱ pulse duration. We simulated the thermal-mechanical process near the surface of Ni₃Al based alloy with our STEIPIB codes. The surface morphology and the cross-section microstructures of samples were observed with SEM, the composition of the sample surface layer was determined by X-ray Energy Dispersive Spectrometry (XEDS) and the microstructure on the surface was observed by Transmission Electron Microscope (TEM). The results show that heating rate increases with the current density of IPIB and cooling rate reached highest value less than 150 A/㎤. The irradiation of IPIB induced the segregation of Mo and adequate beam parameter can improve anti-oxidation property of IC6 alloy. Some craters come from extraneous debris and liquid droplets, and some maybe due to the melting of the intersection region of interphase. Increasing the pulse number enlarges average size of craters and decreases number density of craters.
SYNTHESIS AND FIELD EMISSION PROPERTIES OF SnS_2 AND In-DOPED SnS_2 WITH HIERARCHICAL STRUCTURE
H. X. ZHONG,C. X. WANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2011 NANO Vol.6 No.5
A simple hydrothermal route was employed to prepare flower-like SnS_2 and In-doped SnS_2 by using biomolecular L-cysteine as sulfur source. The synthetic samples were characterized by X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy in detail. Furthermore, the field emission from both the materials was investigated, it was found that both of them have excellent field emission properties, and the doped In has enhanced the field emission properties.
Wang, M.-Z.,Abe, K.,Abe, K.,Abe, T.,Adachi, I.,Aihara, H.,Asano, Y.,Aso, T.,Aulchenko, V.,Aushev, T.,Bakich, A. M.,Bay, A.,Bizjak, I.,Bondar, A.,Bozek, A.,Brax10d,ko, M.,Browder, T. E.,Chang, M.-C. American Physical Society 2004 Physical Review Letters Vol.92 No.13
<P>We report the first observation of a b-->u type charmless baryonic B decay, B+-->pppi(+), as well as b-->s type B0-->ppK0 and B+-->ppK(*+) decays. The analysis is based on a 78 fb(-1) data sample recorded on the Upsilon(4S) resonance with the Belle detector at KEKB. We find B(B+-->pppi(+))=(3.06(+0.73)(-0.62)+/-0.37)x10(-6), B(B0-->ppK0)=(1.88(+0.77)(-0.60)+/-0.23)x10(-6), and B(B+-->ppK(*+))=(10.3(+3.6+1.3)(-2.8-1.7))x10(-6). We also update B(B+-->ppK+)=(5.66(+0.67)(-0.57)+/-0.62)x10(-6) and present an upper limit on B(B0-->ppK(*0)) at the 90% confidence level. A common feature of the observed decay modes is threshold peaking in baryon pair invariant mass.</P>
Wang, T. G.,Dong, Y.,Gebrekidan, B. A.,Liu, Y. M.,Fan, Q. X.,Kim, K. H. Springer Science + Business Media 2017 Acta metallurgica sinica Vol.30 No.7
<P>The Cr-Si-N coatings were prepared by combining system of high-power impulse magnetron sputtering and pulsed DC magnetron sputtering. The Si content in the coating was adjusted by changing the sputtering power of the Si target. By virtue of electron-probe microanalysis, X-ray diffraction analysis and scanning electron microscopy, the influence of the Si content on the coating composition, phase constituents, deposition rate, surface morphology and microstructure was investigated systematically. In addition, the change rules of micro-hardness, internal stress, adhesion, friction coefficient and wear rate with increasing Si content were also obtained. In this work, the precipitation of silicon in the coating was found. With increasing Si content, the coating microstructure gradually evolved from continuous columnar to discontinuous columnar and quasi-equiaxed crystals; accordingly, the coating inner stress first declined sharply and then kept almost constant. Both the coating hardness and the friction coefficient have the same change tendency with the increase of the Si content, namely increasing at first and then decreasing. The Cr-Si-N coating presented the highest hardness and average friction coefficient for an Si content of about 9.7 at.%, but the wear resistance decreased slightly due to the high brittleness. The above phenomenon was attributed to a microstructural evolution of the Cr-Si-N coatings induced by the silicon addition.</P>
Wang, M.,Zhang, H.,Li, L.,Liu, X.,Hong, F.,Li, R.,Song, H.,Gui, M.,Shen, J.,Zhu, W.,Wang, J.,Zhou, L.,Jeong, J.H. Elsevier Sequoia 2014 JOURNAL OF ALLOYS AND COMPOUNDS Vol.585 No.-
Eu<SUP>3+</SUP> activated micrometer Y<SUB>2</SUB>MoO<SUB>6</SUB> phosphors with strong red emission bands, under a broad-band excitation wavelength range of 340-400nm, have been prepared by solid-state reaction and sol-gel technique. The photoluminescence indicates that the materials exhibit a characteristic red emission peak of Eu<SUP>3+</SUP> ions at 612nm. Compared with the material obtained by sol-gel method, the Y<SUB>2</SUB>MoO<SUB>6</SUB>:Eu prepared using solid state method showed much stronger red emission under the n-UV excitation. The broad excitation bands are assigned to charge transfer (CT) bands originating from the ligands (O) to the central ions Mo<SUP>6+</SUP>. About 12nm shift of excitation bands in Y<SUB>2</SUB>MoO<SUB>6</SUB>:Eu was found. With a decrease of the crystalline size, the excitation bands of O-Mo CT shift to the short wavelength. The origin of CT shift in macromaterial Y<SUB>2</SUB>MoO<SUB>6</SUB>:Eu was investigated quantitatively from the chemical bond viewpoint. All constituent chemical bonds in the crystal with or without oxygen vacancy were considered. The changes of average energy gap of the chemical bond Mo-O and the environmental factor (h<SUB>e</SUB>) surrounding Mo<SUP>6+</SUP> ions in the crystals were discussed quantitatively. Calculated results from two different methods analysis specifications showed that the origin of CT blue-shifts mainly come from the vacancies of O6 sites within the crystals.
( Wang,L. X. ),( I. L. Choi ),( J. H. Lee ),( H. M. Kang ) 강원대학교 농업생명과학연구원(구 농업과학연구소) 2019 강원 농업생명환경연구 Vol.31 No.2
Oxygen transmission rate (OTR) films of 1,300 and 10,000 cc/m<sup>2</sup>/day/atm, perforated (P), micro-perforated (MP), and vacuum (V) films were investigated for suitability in maintaining the quality and prolonging shelf life of asparagus during cold storage. An additional investigation using 60% (v/v) carbon dioxide treatment (V + 60% CO<sub>2</sub>) was also performed. All samples lost fresh weight over time, P and V + 60% CO<sub>2</sub> had the highest and lowest fresh weight loss rate by the last day. Only 1,300 cc and 10,000 cc OTR films kept the asparagus at a marketable value, the least off-odor was detected in P, and the worst was in V + 60% CO<sub>2</sub> in final day. The V + 60% CO<sub>2</sub> resulted in lower firmness in asparagus tips, and the V resulted in the lowest firmness in stems. Although, little color changes happened in all treatments, the V + 60% CO<sub>2</sub> treatment had greater soluble solids content and hue angle. The highest ethylene concentration was detected in the V film. The CO<sub>2</sub> and O<sub>2</sub> levels of the 1,300 cc and 10,000 cc OTR treatments were more suitable for asparagus storage. In general, based on the visual quality, 1,300 cc and 10,000 cc OTR films were more effective for asparagus cold storage. To some extent, high CO<sub>2</sub> treatment exhibited a positive effect on maintaining internal quality, fresh weight and color of asparagus.
ANALYSIS OF THE PHASE STABILITY OF FINE Fe.90Ni.10ALLOY PARTICLES
H. M. Widatallah,R. S. Huang,Y. F. Hsia,X. M. Lee,J. H. Wang,H. X. Lu 한국자기학회 1995 韓國磁氣學會誌 Vol.5 No.5
A set of Fe_(1-x)Ni_x(x=0.10, 0.25, 0.30, 0.50, 0.60, 0.75, 0.85) fine particles prepared by the gas evaporation technique was studied by Moossbauer, XRD and other techniques. The XRD and Moossbauer patterns of the sample with x=0.10(Fe_(90)Ni_(10)) were found to be exceptionally different, showing an austenite phase stability when the particles are quenched. This phase stability is quite different from that of the corresponding bulk alloy. Using binomial distribution fits of the Moossbauer spectra of the particles in terms of nearest and text nearest neighbour configurations around the Fe atoms, and analysis of this phase stability is given. The changes in the relative intensities of the resulting magnetic sextets are used to determine the increase in martensite following the austenite-martensite transformation process. The stable austenite can, therefore, be determined. This stability may be related to the oxide surface layer and the small number of atoms of these fine particles.