检索结果-南通市图书馆

Mass Spectral Fragmentation of (S,S)-N,N′-Bis [1-(hydroxymethyl)alkyl]anthracene/Naphthalene-1,8-dicarboxamides under Electron Impact Ionization Conditions

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2006年第6期22卷 756-759页

作者： jiao peng ZHANG Qi-han XU Jia-xi Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education College of Chemistry and Molecular Engineering Peking University Beijing 100871 China

The mass spectrometric fragmentation of （ S, S） -N, N＇-bis [ 1- （hydroxymethyl） alkyl] anthracene/naphthalene-1, 8-dicarboxamides was investigated with the aid of mass-analyzed ion kinetic energy spectrometry and the elemental compositions of important fragment ions were determined by accurate mass measurement under electron impact ionization conditions. All the compounds could eliminate formaldehyde. The [ M-CH2O] ions could also eliminate imine, aziridine, aziridinone, 2-amonoalkan-1-ol, water, and other fragments. Several cyclizations were observed under electron impact ionization.

关键词： Biscarboxamide EI-MS Fragmentation Cyclization

Insight into evolution of invasive patterns on fingering phenomenon during immiscible two-phase flow through pore structure

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2024年第5期21卷 3307-3325页

作者： Yu Li Hui-Qing Liu Chao peng peng jiao Wai Lam Loh Qing Wang State Key Laboratory of Petroleum Resources and Engineering China University of PetroleumBeijing102249China Department of Mechanical Engineering National University of Singapore117575Singapore Oil and gas production Business Department Kunlun Shuzhi Technology Co.LTDBeijing100040China

Understanding fingering, as a challenge to stable displacement during the immiscible flow, has become a crucial phenomenon for geological carbon sequestration, enhanced oil recovery, and groundwater protection. Typically governed by gravity, viscous and capillary forces, these factors lead invasive fluids to occupy pore space irregularly and incompletely. Previous studies have demonstrated capillary numbers,describing the viscous and capillary forces, to quantificationally induce evolution of invasion *** the evolution mechanisms of invasive patterns have not been deeply elucidated under the constant capillary number and three variable parameters including velocity, viscosity, and interfacial *** research employs two horizontal visualization systems and a two-phase laminar flow simulation to investigate the tendency of invasive pattern transition by various parameters at the pore scale. We showed that increasing invasive viscosity or reducing interfacial tension in a homogeneous pore space significantly enhanced sweep efficiency, under constant capillary number. Additionally, in the fingering crossover pattern, the region near the inlet was prone to capillary fingering with multi-directional invasion, while the viscous fingering with unidirectional invasion was more susceptible occurred in the region near the outlet. Furthermore, increasing invasive viscosity or decreasing invasive velocity and interfacial tension promoted the extension of viscous fingering from the outlet to the inlet, presenting that the subsequent invasive fluid flows toward the outlet. In the case of invasive trunk along a unidirectional path, the invasive flow increased exponentially closer to the outlet, resulting in a significant decrease in the width of the invasive interface. Our work holds promising applications for optimizing invasive patterns in heterogeneous porous media.

关键词： Immiscible two-phase flow Fingering phenomenon Invasive pattern Capillary number Parameters optimization

Rational architecture design of yolk/double-shells Si-based anode material with double buffering carbon layers for high performance lithium-ion battery

在线全文

学校读者我要写书评

暂无评论

Green Energy & Environment 2021年第4期6卷 517-527页

作者： Zhenyu Wu Jing Luo jiao peng Hong Liu Baobao Chang Xianyou Wang National Base for International Science&Technology Cooperation Hunan Province Key Laboratory of Electrochemical Energy Storage and ConversionSchool of ChemistryXiangtan UniversityXiangtan411105China Key Laboratory of Materials Processing and Mold of Ministry of Education Zhengzhou UniversityHenan450001China

Among the many strategies to fabricate the silicon/carbon composite,yolk/double-shells structure can be regarded as an effective strategy to overcome the intrinsic defects of Si-based anode materials for Li-ion batteries(LIBs).Hereon,a facile and inexpensive technology to prepare silicon/carbon composite with yolk/double-shells structure is proposed,in which the double buffering carbon shells are *** silicon/carbon nanoparticles with core-shell structure are encapsulated by SiO_(2)and external carbon layer,and it shows the yolk/double-shells structure via etching the SiO_(2)sacrificial *** multiply shells structure not only significantly improves the electrical conductivity of composite,but also effectively prevents the exposure of Si particles from the electrolyte ***,the yolk/double-shells structure can provide enough space to accommodate the volume change of the electrode during charge/discharge process and avoid the pulverization of Si ***,the as-prepared YDS-Si/C shows excellent performance as anode of LIBs,the reversible capacity is as high as 1066 mA h g^(-1) at the current density of 0.5 A g^(-1) after 200 *** the same time,the YDS-Si/C has high capacity retention and good cyclic ***,the unique architecture design of yolk/double-shells for Si/C composite provides an instructive exploration for the development of next generation anode materials of LIBs with high electrochemical performances and structural stability.

关键词： Silicon/carbon composite Structure design Yolk/double-shells Double buffering carbon layers Li-ion batteries

Mass Spectrometric Fragmentation of 1,8-Bis[4-substituted- (oxazolin-2-yl)] anthracenes: Ring-contraction Rearrangement of Oxazoline Ring under Electron-Impact Ionization Conditions

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2006年第6期22卷 753-755页

作者： jiao peng MA Lin-ge ZHANG Qi-han XU Jia-xi Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education College of Chemistry and Molecular Engineering Peking University Bering 100871 P. R. China

The mass spectrometric fragmentation of 1,8-bis [ 4-substituted （oxazolin-2-yl） ] anthracenes （AnBOXes） was investigated by using mass-analyzed ion kinetic energy spectrometry under electron-impact ionization conditions. All the compounds could undergo a ring contraction by the loss of an RCH = CH2 molecule to form 1-oxazirinyl-8-（oxazolin- 2-yl） anthracene ions, which could further lose an R radical, followed by the loss of oxazoline. These ions could also eliminate an R radical and subsequently undergo ring-contraction rearrangements to lose a CHCH2O fragraent and an epoxide molecule, respectively. The ions that are formed could further lose CHCH2O and CH2 = CH fragments. Several ring-contraction rearrangements of the oxazoline ring were observed under electron-impact ionization conditions.

关键词： Bis-oxazoline EI-MS Fragmentation Ring contraction

Effects of Shrub on Runoff and Soil Loss at Loess Slopes Under Simulated Rainfall

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2017年第4期27卷 589-599页

作者： XIAO Peiqing YAO Wenyi SHEN Zhenzhou YANG Chunxia LYU Xizhi jiao peng Key Laboratory of the Loess Plateau Soil Erosion and Water Loss Process and Control of Ministry of Water Resources Yellow RiverInstitute of Hydraulic ResearchZhengzhou 450003China

Improved understanding of the effect of shrub cover on soil erosion process will provide valuable information for soil and water conservation *** rainfall simulations were conducted to determine the effects of shrubs on runoff and soil erosion and to ascertain the relationship between the rate of soil loss and the runoff hydrodynamic *** these simulations a 20° slope was subjected to rainfall intensities of 45,87,and 127 mm/*** average runoff rates ranged from 0.51 to 1.26 mm/min for bare soil plots and 0.15 to 0.96 mm/min for shrub *** soil loss rates varied from 44.19 to 114.61 g/(min·m^2) for bare soil plots and from 5.61 to 84.58 g/(min·m^2) for shrub *** was a positive correlation between runoff and soil loss for the bare soil plots,and soil loss increased with increased runoff for shrub plots only when rainfall intensity is 127 mm/*** and soil erosion processes were strongly influenced by soil surface conditions because of the formation of erosion pits and *** unit stream power was the optimal hydrodynamic parameter to characterize the soil erosion *** soil loss rate increased linearly with the unit stream power on both shrub and bare soil *** unit stream power values were 0.004 m/s for bare soil plots and 0.017 m/s for shrub plots.

关键词： runoff soil loss shrub bare soil rainfall intensity loess slope

Dispersion polymerization of anionic polyacrylamide in an aqueous salt medium

在线全文

学校读者我要写书评

暂无评论

Petroleum Science 2010年第3期7卷 410-415页

作者： Lu jiao peng Bo Li Mingyuan Lin Meiqin Dong Zhaoxia Enhanced Oil Recovery Research Center China University of Petroleum Beijing 102249 China

Anionic polyacrylamide dispersions were prepared by dispersion polymerization in an aqueous salt medium, using acrylamide（AM） and acrylic acid（AA） as monomers and anionic polyelectrolytes as stabilizer. Effects of salt concentration, and molecular weight and concentration of stabilizers on the stability of the dispersions were investigated using a HAAKE rheometer and optical microscopy. The results showed that stable anionic polyacrylamide dispersions, consisting of smooth, spherical, polydisperse particles, could be obtained under the conditions of salt concentration ranging from 26 wt% to 30 wt%, concentration of stabilizers from 1.2 wt% to 1.8 wt%, and intrinsic viscosity of stabilizers from 2.98 dL·g^-1 to 3.74 dL·g^-1. The apparent viscosity of the stable dispersions changed very little with the shear rate, showing Newton fluid behavior.

关键词： Dispersion polymerization aqueous salt medium stability micromorphology apparentviscosity

Repetitive cleaning of a stainless steel first mirror using radio frequency plasma

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2017年第10期19卷 83-90页

作者： jiao peng Rong YAN Rui DING Junling CHEN Dahuan ZHU Zengming ZHANG Institute of Plasma Physics Chinese Academy of Sciences Hefei 230031 People＇s Republic of China University of Science and Technology of China Hefei 230026 People＇s Republic of China The Center of Physical Experiments University of Science and Technology of China Hefei 230026 People＇s Republic of China

First mirrors（FMs） are crucial components of optical diagnostic systems in present-day tokamaks and future fusion reactors. Their lifetimes should be extremely limited due to their proximity to burning plasma, greatly influencing the safe operation of corresponding *** cleaning is expected to provide a solution to the frequent replacement of contaminated FMs, thus prolonging their lifetimes. Three repetitive cleaning cycles using radio frequency plasma were applied to stainless steel（SS） FM samples, to evaluate the change of the mirrors＇ optical properties and morphology during each cycle. Amorphous carbon films were deposited on mirror surfaces under identical conditions in three cycles. In three cycles with identical cleaning parameters, the total reflectivity was restored at up to 95%. Nevertheless, with successive cleaning cycles, the FM surfaces gradually appeared to roughen due to damage to the grain boundaries. Correspondingly, the diffuse reflectivity increased from a few percent to 20%and 27% after the second and third cycles. After optimizing the cleaning parameters of the second and third cycles, the roughness showed a significant decrease, and simultaneously the increase of diffuse reflectivity was remarkably improved.

关键词： first mirror stainless steel lifetime repetitive cleaning reflectivity

Study on plasma cleaning of the large-scale first mirror of the charge exchange recombination spectroscopy diagnostic on EAST

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2020年第3期22卷 24-33页

作者： jiao peng Rong YAN Junling CHEN Rui DING Yingying LI Fali CHONG Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People’s Republic of China Xuzhou University of Technology Xuzhou 221000People’s Republic of China

In the Experimental Advanced Superconducting Tokamak(EAST),the reflectivity of the charge exchange recombination spectroscopy(CXRS)first mirror(FM)was dramatically dropped down to 20%of the original value after the operation of two EAST experimental campaigns from 2014-2015,leading to degradation of the signal intensity of the CXRS diagnostic to an unacceptably low *** radio frequency(RF)plasma cleaning of the CXRS FM with a dimension of 303×81×76 mm3 and a small curvature of 0.008 mm-1 was performed to remove deposits to recover the *** 168 h cleaning by RF plasma,the maximum specular reflectivity of the FM could reach 92%of the original value at 532 nm,making the cleaned CXRS FM eligible to be reused for the CXRS diagnostic in the 2016 EAST *** tests of sputtering polished mirror samples were performed to explore the cleaning uniformity and possible damage to the mirror *** specular reflectivity did not show obvious dependence on locations along the surface with the same cleaning *** measured surface roughness gradually increased with sputtering *** reflectivity remained almost unchanged regardless of different sputtering times and locations,indicating negligible damage to the FM surface even after 100 h *** recontaminated CXRS FM in the 2016 EAST campaign was firstly cleaned for 81 h,and the least reflectivity recovery for areas with relatively thick deposits was only 40%.After continuing cleaning to 147 h,redeposition of the sputtered residual deposits on the FM surface was *** the future for in situ cleaning of the FMs in EAST and ITER,deposits should be removed timely when they are very thin taking into account a very long cleaning time and presumable redeposition of thick and nonuniform deposits.

关键词： first mirror CXRS EAST plasma cleaning cleaning uniformity

Development of a New Cold-Tolerant Maize(Zea mays L.)Germplasm Using the ICE1 Gene from Arabidopsis thaliana

在线全文

学校读者我要写书评

暂无评论

Phyton-International Journal of Experimental Botany 2022年第8期91卷 1709-1719页

作者： Jing Qu Shuang Liu peng jiao Zhenzhong Jiang Jianbo Fei Shuyan Guan Yiyong Ma College of Agronomy Jilin Agricultural UniversityChangchun130118China College of Life Sciences Jilin Agricultural UniversityChangchun130118China

To develop cold-tolerant maize germplasms and identify the activation of INDUCER OF CRT/DRE-BINDING FACTOR EXPRESSION(ICE1)expression in response to cold stress,RT-PCR was used to amplify the complete open reading frame sequence of the ICE1 gene and construct the plant expression vector *** maize embryos and calli were transformed with the recombinant vector using Agrobacterium tumefaciens-mediated *** the regenerated plantlets,three T1 lines were screened and identi-fied by PCR.A Southern blot analysis showed that a single copy of the ICE1 gene was integrated into the maize(Zea mays L.)genomes of the three T1 *** low temperature-stress conditions(4°C),the relative conductivity levels decreased by 27.51%–31.44%,the proline concentrations increased by 12.50%–17.50%,the malondialdehyde concentrations decreased by 16.78%–18.37%,and the peroxidase activities increased by 19.60%–22.89%in the T1 lines compared with those of the control.A real-time quantitative PCR analysis showed that the ICE1 gene was ectopically expressed in the roots,stems,and leaves of the T1 ***1 positively regulates the expression of the CBF genes in response to cold ***,this study showed the successful transformation of maize with the ICE1 gene,resulting in the generation of a new maize germplasm that had increased tolerance to cold stress.

关键词： Maize ICE1 cold tolerance inducer maize Arabidopsis thaliana