34 results on '"Z-C, Yan"'
Search Results
2. Elastic scattering of positive muons from He3 and He4
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M.-S. Wu, Y. Zhang, G.-A. Yan, J.-Y. Zhang, K. Varga, and Z.-C. Yan
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- 2023
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3. Microstructure and corrosion behavior of Al95−xNixY5 (x = 7,10) glassy ribbons
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X. N. Wang, Y. Feng, H. Z. Liu, H. Zhang, Z. C. Yan, and Y. W. Bai
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General Chemical Engineering ,General Chemistry - Abstract
The Al95−xNixY5 ribbon x = 7 has a Y-depleted extra film and has a longer passive zone in the polarization curve and higher corrosion resistance than x = 10.
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- 2022
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4. [The status of projects funded in division of preventive medicine in National Natural Science Foundation of China from the financial year 2007-2021]
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Z H, Peng and Z C, Yan
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China ,Humans ,Nutritional Status ,Natural Science Disciplines ,Health Facilities - Abstract
It is of great significance to analyze the configuration of programs funded by the National Natural Science Foundation of China using funding data in the field of preventive medicine from 2007 to 2021. The analysis mainly focused on the funding status of the program, funding amount, funded institutions and personnel. A total of 5 349 programs in the discipline of preventive medicine were funded over the last 15 years. The funding amount in this discipline accounted for a relatively low proportion in the total funding amount of the Department of Medical Sciences and this proportion also showed a decreasing trend. Non-infectious disease epidemiology, human nutrition, and health toxicology were the top three subdisciplines of all funded programs in preventive medicine. The proportion of programs led by young scholars was gradually rising over the years, and young scholars were playing an increasingly influential role in scientific research. The funding status among each subdiscipline and institution also varied. The results of this study reflected the thriving of preventive medicine. Meanwhile, some problems and dilemmas were also revealed in its current development. Hopefully, this study could provide valuable information for institutions and preventive medicine researchers to apply for National Natural Science Foundation, and promote the long-term development of preventive medicine in the future.分析国家自然科学基金预防医学领域各类型项目的资助情况具有重要意义。本研究汇总2007—2021年国家自然科学基金预防医学领域各类型项目的资助数据,主要针对各类型项目立项数、资助金额、受资助依托单位情况以及受资助人员情况等进行系统分析。15年间预防医学学科共计资助各类型项目5 349项,资助金额占医学科学部资助总金额比例较低,且有占比下降的趋势。非传染病流行病学、人类营养和卫生毒理是获得资助项目数排前3位的分支学科。青年科研人员近年来主持的项目占比逐渐增加,在科学研究中发挥的作用越来越大。各分支学科、各申报单位的情况也有较大差别。以上结果反映出预防医学学科目前的蓬勃发展态势,同时也暴露出当前预防医学学科基础研究中存在的问题,可为各研究单位、预防医学科技工作者未来申报国家自然科学基金项目提供参考,促进预防医学学科的长远发展。.
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- 2022
5. Non-Born-Oppenheimer confined variational calculation of low-energy Ps- H2 scattering
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W. Du, M.-S. Wu, J.-Y. Zhang, Y. Qian, K. Varga, and Z.-C. Yan
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- 2022
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6. Microstructure and corrosion behavior of Al
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X N, Wang, Y, Feng, H Z, Liu, H, Zhang, Z C, Yan, and Y W, Bai
- Abstract
In this work, we correlate the microstructure and passivation of the Al
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- 2021
7. [Adrenal ablation therapy for primary aldosteronism related resistant hypertension: key technology and clinical application perspectives]
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Z M, Zhu, Z G, Zhao, H X, Zhang, H B, He, and Z C, Yan
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Technology ,Hyperaldosteronism ,Hypertension ,Humans - Abstract
以原发性醛固酮增多症(PA)为代表的肾上腺疾病是内分泌高血压的主要病因,10%~20%的高血压患者合并PA,PA还是导致难治性高血压、心力衰竭、心肌梗死及卒中等的重要原因。PA的诊断依赖于血生化检测、肾上腺影像学及必要时肾上腺静脉取血。药物干预或外科手术是PA的主要治疗方法,但常会出现药物不能耐受及不适合手术的问题。肾上腺消融术是一种安全、有效、不良反应较小的干预措施,也是对现有PA治疗的重要补充。该文对肾上腺消融术治疗PA相关高血压的临床应用现况、技术关键及应用前景进行了评述。.
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- 2021
8. Erratum: Transition frequencies between the 2S and 2P states of the lithiumlike ion O5+ [Phys. Rev. A 100 , 032505 (2019)]
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Z.-C. Yan and L. M. Wang
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Physics ,Atomic physics ,Ion - Published
- 2021
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9. Corrosion comparison of free and roller surfaces of Fe
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H, Zhang, Z C, Yan, Q, Chen, Z G, Qi, Y, Feng, H Z, Liu, X Y, Li, and W M, Wang
- Abstract
The corrosion resistance of the free surface (FS) and roller surface (RS) of Fe
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- 2021
10. Polarizabilities of hydrogen molecules calculated without using the Born-Oppenheimer approximation
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Z.-C. Yan, L. M. Wang, X. J. Wei, D. Sun, and Y. P. Zhang
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Physics ,Hydrogen molecule ,Born–Oppenheimer approximation ,01 natural sciences ,010305 fluids & plasmas ,symbols.namesake ,Dipole ,0103 physical sciences ,symbols ,Physics::Atomic Physics ,Atomic physics ,010306 general physics ,Wave function ,Order of magnitude - Abstract
The static dipole polarizabilities of the first three lowest states of hydrogen molecules ${\mathrm{H}}_{2}$, HD, and ${\mathrm{D}}_{2}$ are calculated using variationally generated wave functions in Hylleraas coordinates without using the Born-Oppenheimer approximation. Our results for ${\mathrm{H}}_{2}$ and HD are two orders of magnitude more accurate than the best literature values. We also improve the previous best results for ${\mathrm{D}}_{2}$.
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- 2021
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11. Treatment of chronic subdural hematoma by novel YL-1 hollow needle aspiration drainage system (697 cases report)
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Li Chen, X. D. Wang, L. Yang, Z. C. Yan, Lun Dong, L. She, Wei Wu, and Hengzhu Zhang
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Adult ,Male ,medicine.medical_specialty ,Neurology ,Adolescent ,Dermatology ,Young Adult ,03 medical and health sciences ,0302 clinical medicine ,Epidural hematoma ,Chronic subdural hematoma ,Recurrence ,medicine ,Humans ,Minimally Invasive Surgical Procedures ,030212 general & internal medicine ,Drainage system (agriculture) ,Aged ,Neuroradiology ,Aged, 80 and over ,Urokinase ,geography ,geography.geographical_feature_category ,business.industry ,General Medicine ,Middle Aged ,medicine.disease ,Urokinase-Type Plasminogen Activator ,Surgery ,Psychiatry and Mental health ,Treatment Outcome ,Needles ,Hematoma, Subdural, Chronic ,Drainage ,Female ,Neurology (clinical) ,Neurosurgery ,Brain tissue injury ,business ,030217 neurology & neurosurgery ,medicine.drug - Abstract
It is written to discuss the effect and syndromes of novel YL-1 hollow needle aspiration drainage system to treat chronic subdural hematoma. Collecting clinical data about 697 patients with chronic subdural hematoma in neurosurgery of People' Hospital in North Jiangsu from January 2004 to December 2014, including clinical manifestation, imaging data, operation time, postoperative complications and prognostic factors and so on. 593 patients got cured, 53 patients with recurrence, 19 patients with acute subdural hematoma, 13 patients with poor drainage, 9 case of patients with acute epidural hematoma, puncture failure in 6 cases, 3 cases of pulmonary infection, one got intracranial hemorrhage (brain stem and basal ganglia hemorrhage). The total time of the operation is 15-28 min, the mean time is 18 ± 3.6 min, the average retention time of novel YL-1 hollow needle aspiration drainage system was 2.6 ± 1.3 days, the average use of urokinase was 30,000 ± 2.10,000 units. It takes a short time for novel YL-1 hollow needle aspiration drainage system to treat chronic subdural hematoma without any syndromes like brain tissue injury, tension pneumocrania, intracranial infection and so on. The clinical cure rate is 85.08 %, recurrence rate is 7.6 %. Using novel YL-1 hollow needle aspiration drainage system to treat chronic subdural hematoma is such a minimally invasive surgical technology which has a higher curative rate, small damage, is also easy to operate with security and less severe complications.
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- 2016
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12. Theory and computational methods for high precision spectra of few-electron atomic systems
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LiMing Wang, Z.-C. Yan, and WanPing Zhou
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Physics ,chemistry.chemical_element ,Electron ,Effective nuclear charge ,Schrödinger equation ,Computational physics ,symbols.namesake ,chemistry ,Atom ,symbols ,Physics::Atomic Physics ,Relativistic quantum chemistry ,Hamiltonian (quantum mechanics) ,Quantum ,Helium - Abstract
Due to modern precision laser technology, the spectra of some few-electron atomic systems (such as hydrogen, helium, lithium, beryllium) could be measured to very high accuracy. A comparison between high precision experimental and theoretical results supplies us with a practicable method to test fundamental physical theories, to determine fundamental physical constants, and to extract nuclear properties, such as the nuclear charge radius. However, it is not an easy task to calculate the spectrum of an atom to a precision that matches the corresponding experimental precision. In order to achieve this goal, we need to take electron correlation effects, relativistic effects, and quantum electrodynamic (QED) effects into consideration and evaluate them to a sufficiently high accuracy. In the past several decades, significant progress has been made on high precision calculations of few-electron atomic systems, due to advances of computer technologies and persistent efforts in this area. The main purpose of this article is to give a survey on high precision calculations of few-electron atomic systems, including the effective Hamiltonian, the solutions to the Schrodinger equation, calculations of relativistic and QED effects, the finite nuclear mass effect, and the effect due to the nuclear charge radius. Finally, we give some perspectives for the future.
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- 2021
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13. LncRNA HOTAIR participates in the development and progression of adrenocortical carcinoma via regulating cell cycle
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Z-C, Yan, L, He, J-H, Qiu, W-T, Deng, J-R, Lu, Z, Yuan, D-J, Liu, R-Q, Zheng, and W, Jiang
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Male ,Cell Cycle ,Middle Aged ,Adrenal Cortex Neoplasms ,Disease-Free Survival ,Up-Regulation ,Gene Expression Regulation, Neoplastic ,Risk Factors ,Cell Line, Tumor ,Databases, Genetic ,Adrenocortical Carcinoma ,Disease Progression ,Humans ,Female ,RNA, Long Noncoding ,Cell Proliferation ,Neoplasm Staging ,Signal Transduction - Abstract
To explore the role of HOTAIR in the pathogenesis of adrenocortical carcinoma (ACC) and its underlying mechanism.Differentially expressed lncRNA (HOTAIR) in ACC was screened out from the GEO database. The survival analysis and ROC curve were performed according to HOTAIR expressions in ACC patients. The correlation between HOTAIR expression and clinical information of ACC patients was analyzed by chi-square test. The univariate and multivariate COX regression analysis was carried out to analyze the relationship between HOTAIR expression, disease-free survival (DFS) and overall survival (OS) of ACC patients. We then detected HOTAIR expression in 77 ACC tissues and 30 normal tissues by qRT-PCR (quantitative Real-time polymerase chain reaction). ACC cell lines were further screened out for the following in vitro experiments. After altering HOTAIR expression in ACC cells by plasmid transfection, proliferation and cell cycle were detected by Cell Counting Kit-8 (CCK-8) and colony formation assay, respectively. Finally, Western blot was utilized to detect expressions of cell cycle-related genes in ACC cells.HOTAIR was overexpressed in ACC tissues than that of normal tissues. HOTAIR expression was remarkably increased in ACC with T3 and T4 stage than that of T1 and T2 stage. Moreover, HOTAIR expression was remarkably increased in ACC with stage III and IV than that of stage I and II. HOTAIR was an independent prognostic factor for DFS and OS of ACC patients. For in vitro experiments, inhibited proliferation and arrested cell cycle were observed in H295R cells transfected with si-HOTAIR. Opposite results were obtained after SW-13 cells were transfected with HOTAIR overexpression plasmid. Furthermore, expressions of cell cycle-related genes, including Cyclin D1, p-Rb and p-GSK3β were remarkably decreased after HOTAIR knockdown.We demonstrated for the first time that HOTAIR is overexpressed in ACC and is a prognostic risk factor in ACC patients. HOTAIR participates in the development and progression of ACC via shortening cell cycle and promoting proliferation of ACC cells.
- Published
- 2018
14. 172 Effects of net energy levels on feed intake pattern and growth performance of growing-finishing gilts monitored using a computerized feed intake recording system
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Z J Yuan, Z C Yan, YaKuan Huang, Zhikai Zeng, Liqiang Zhu, D F Sun, H Zeng, Z Wang, and Zhiyuan Chen
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ORAL PRESENTATIONS ,Animal science ,Net energy ,Genetics ,Environmental science ,Animal Science and Zoology ,General Medicine ,Recording system ,Food Science - Abstract
This study evaluated the effects of dietary net energy concentrations on feeding behavior and growth performance of growing-finishing pigs monitored using a feed intake recording equipment (FIRE). Two hundred and sixteen (48.8 ± 5.6 kg) gilts were blocked by bodyweight and assigned randomly to 1 of 3 dietary treatments, which included low (2,350 kcal/kg), medium (2,450 kcal/kg), and high (2,550 kcal/kg) dietary NE levels. Pigs were housed in 18 pens for 68 d in four phases with 12 pigs and one FIRE station per pen. Bodyweight, feed consumption, and the amount of time and visit at the station of individual pigs were monitored every day by using FIRE. Pigs fed low NE diet spent more time (min) at the station during the first two weeks and visited the station more times with fewer amounts of time (min) per visit after two weeks compared with pigs fed medium and high levels of NE diets (P < 0.05). The speed (g/min) and amount (g/visit) of feed intake were lower (P < 0.05) during phase 3 and the overall period in low NE diet compared with pigs fed medium NE diet. Pigs fed medium NE diet tended to have a greater (P = 0.066) average daily feed intake at phase 4 than pigs fed low NE diet. Increasing NE levels linearly improved (P < 0.05) average daily gain, feed conversion ratio, and final BW during phase 3 and the overall period. However, the overall energy efficiency (Mcal NE/ kg gain) was linearly decreased with increasing NE levels. In conclusion, decreasing dietary NE to 2350 Mcal/kg resulted in more visits to feeders with slow ingestion speed compared with pigs fed diets with 2450 or 2550 Mcal/kg NE. Increasing dietary NE levels linearly improved daily gain and feed conversion ratio, but linearly decreased energy efficiency.
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- 2019
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15. [Analysis of the application and funding projects of National Natural Science Foundation of China in the field of burns and plastic surgery from 2010 to 2016]
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Z C, Zhang, D, Dou, X Y, Wang, D H, Xie, and Z C, Yan
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China ,Cicatrix ,Financial Support ,Humans ,Natural Science Disciplines ,Surgery, Plastic ,Burns ,Foundations - Abstract
We analyzed the data of application and funding projects of the National Natural Science Foundation of China (NSFC) during 2010-2016 in the field of burns and plastic surgery and summarized the NSFC funding pattern, the research hotspots, and weaknesses in this field. The NSFC has funded 460 projects in the field of burns and plastic surgery, with total funding of RMB 227.96 million. The scientific issues involved in the funding projects include orthotherapy against malformations, wound repair, basic research of burns, skin grafting, scars prevention, and regeneration of hair follicle and sweat glands. The research techniques involved in the funding projects are diversified. NSFC plays an important role in the scientific research and talents training in the field of burns and plastic surgery.
- Published
- 2017
16. A new F-wave resonant state in the e+-He+ system
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Z. C. Yan and Y. K. Ho
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Physics ,History ,Quantum electrodynamics ,State (functional analysis) ,Computer Science Applications ,Education ,F wave - Abstract
Synopsis Using the complex scaling method, together with employing highly correlated Hylleraas wave functions in which all the interparticle coordinates are included, we have calculated for the first time a F-wave resonance state in the positron-helium positive ion system near the postronium (ground state) formation threshold.
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- 2020
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17. Calculations of long-range three-body interactions for Li(2 2S )-Li(22 S )-Li+(1 1S)
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L. Y. Tang, Z. C. Yan, P. G. Yan, and J. F. Babb
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Physics ,History ,Range (particle radiation) ,Atomic physics ,Computer Science Applications ,Education - Abstract
Synopsis Using perturbation theory for energies, we evaluate the additive and nonadditive interaction co-efficients C4, C6 , C7 , C8 and C9 for the Li(22S)-Li(22S)-Li+(11S) system. The obtained coefficients Cn are evaluated with highly accurate variationally-generated nonrelativistic wave functions in Hylleraas coordinates. The nonadditive interaction coefficients depend on the geometrical configurations of this three-body system and on the different position of the ion for each configuration. Our calculations may be of interest for the study of three-body recombination and for constructing precise potential energy surfaces.
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- 2020
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18. Properties of halo nuclei from atomic isotope shifts
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Z.-C. Yan and G.W.F. Drake
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Physics ,Nuclear and High Energy Physics ,chemistry.chemical_element ,Electron ,Effective nuclear charge ,Computational physics ,chemistry ,Self-energy ,Atomic theory ,Halo ,Atomic physics ,Perturbation theory ,Asymptotic expansion ,Helium - Abstract
This paper reviews progress that has been made in obtaining essentially exact solutions to the nonrelativistic three-body problem for helium by a combination of variational and asymptotic expansion methods. The calculation of relativistic and quantum electrodynamic corrections by perturbation theory is discussed, and in particular, methods for the accurate calculation of the Bethe logarithm part of the electron self energy are presented. As an example, the results are applied to the calculation of isotope shifts for the short-lived 'halo' nucleus 6 He relative to 4 He in order to determine the nuclear charge radius of 6 He from high precision spectroscopic measurements carried out at the Argonne National Laboratory. The results demonstrate that the high precision that is now available from atomic theory is creating new opportunities to create novel measurement tools, and helium, along with hydrogen, can be regarded as a fundamental atomic system whose spectrum is well understood for all practical purposes.
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- 2007
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19. Magnetic moments for lithium quartet S states
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Z.-C. Yan
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Condensed Matter::Quantum Gases ,Physics ,Zeeman effect ,Magnetic moment ,Isotope ,Jahn–Teller effect ,Optical physics ,chemistry.chemical_element ,Plasma ,Atomic and Molecular Physics, and Optics ,symbols.namesake ,chemistry ,symbols ,Radiative transfer ,Astrophysics::Solar and Stellar Astrophysics ,Lithium ,Physics::Atomic Physics ,Atomic physics - Abstract
The fully correlated calculations of the Zeeman gJ factors for the first three quartet S states of lithium are presented, including relativistic and radiative corrections of orders α2, α2 m/M, and α3. The isotope shifts in gJ are predicted precisely for various isotopes of lithium.
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- 2002
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20. Variational energies and the Fermi contact term for the low-lying states of lithium: Basis-set completeness
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Haoxue Qiao, Z.-C. Yan, Gordon W. F. Drake, and L. M. Wang
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Physics ,Angular momentum ,Fermi contact interaction ,chemistry.chemical_element ,Term (logic) ,Atomic and Molecular Physics, and Optics ,Combinatorics ,Variational method ,chemistry ,Quantum mechanics ,Physical Sciences and Mathematics ,Lithium ,Hyperfine structure ,Basis set ,Spin-½ - Abstract
Nonrelativistic energies for the low-lying states of lithium are calculated using the variational method in Hylleraas coordinates. Variational eigenvalues for the infinite nuclear mass case with up to 34 020 terms are $\ensuremath{-}7.478\phantom{\rule{0.16em}{0ex}}060\phantom{\rule{0.16em}{0ex}}323\phantom{\rule{0.16em}{0ex}}910\phantom{\rule{0.16em}{0ex}}147(1)$ a.u. for $1{s}^{2}2s{\phantom{\rule{0.16em}{0ex}}}^{2}\phantom{\rule{-0.16em}{0ex}}S$, $\ensuremath{-}7.354\phantom{\rule{0.16em}{0ex}}098\phantom{\rule{0.16em}{0ex}}421\phantom{\rule{0.16em}{0ex}}444\phantom{\rule{0.16em}{0ex}}37(1)$ a.u. for $1{s}^{2}3s{\phantom{\rule{0.16em}{0ex}}}^{2}\phantom{\rule{-0.16em}{0ex}}S$, $\ensuremath{-}7.318\phantom{\rule{0.16em}{0ex}}530\phantom{\rule{0.16em}{0ex}}845\phantom{\rule{0.16em}{0ex}}998\phantom{\rule{0.16em}{0ex}}91(1)$ a.u. for $1{s}^{2}4s{\phantom{\rule{0.16em}{0ex}}}^{2}\phantom{\rule{-0.16em}{0ex}}S$, $\ensuremath{-}7.410\phantom{\rule{0.16em}{0ex}}156\phantom{\rule{0.16em}{0ex}}532\phantom{\rule{0.16em}{0ex}}652\phantom{\rule{0.16em}{0ex}}41(4)$ a.u. for $1{s}^{2}2p{\phantom{\rule{0.16em}{0ex}}}^{2}\phantom{\rule{-0.16em}{0ex}}P$, and $\ensuremath{-}7.335\phantom{\rule{0.16em}{0ex}}523\phantom{\rule{0.16em}{0ex}}543\phantom{\rule{0.16em}{0ex}}524\phantom{\rule{0.16em}{0ex}}688(3)$ a.u. for $1{s}^{2}3d{\phantom{\rule{0.16em}{0ex}}}^{2}\phantom{\rule{-0.16em}{0ex}}D$. The selection of the minimum set of angular momentum configurations is discussed, with the $2P$ and $3D$ states as examples to demonstrate the impact of various configurations on the variational energies. It is shown by numerical example that the second spin function (i.e., coupled to form a triplet intermediate state) has no significant effect on either the variational energies or the spin-dependent Fermi contact term. Results of greatly improved accuracy for the Fermi contact term are presented for all the states considered.
- Published
- 2012
21. Higher-lying resonances in Ps-H scattering below thee+-H−threshold
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Yew Kam Ho and Z.-C. Yan
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Physics ,Quantum defect ,symbols.namesake ,Series (mathematics) ,Scattering ,Rydberg formula ,symbols ,Resonance ,State (functional analysis) ,Atomic physics ,Wave function ,Atomic and Molecular Physics, and Optics ,Energy (signal processing) - Abstract
In this work, we perform a study on high-lying $S$-wave resonances in Ps-H scattering below the ${e}^{+}$-H${}^{\ensuremath{-}}$ threshold. The method of complex-coordinate rotation is applied together with highly correlated wave functions containing all six interparticle distances. Using such Hylleraas bases up to 6412 terms, the energy positions up to the 8$S$ state and the widths up to the 7$S$ state in the Rydberg series converging to the H${}^{\ensuremath{-}}$ threshold are determined. The energies of 4$S$ to 7$S$ states from the present calculations are fitted into the quantum defect formula, from which the energies of higher members in the Rydberg series can be deduced.
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- 2011
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22. Variational upper bounds for low-lying states of lithium
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Z.-C. Yan, L. M. Wang, Haoxue Qiao, and Gordon W. F. Drake
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Physics ,Basis (linear algebra) ,chemistry.chemical_element ,Atomic and Molecular Physics, and Optics ,Calculation methods ,chemistry ,Quantum mechanics ,Physical Sciences and Mathematics ,Lithium ,Atomic physics ,Eigenvalues and eigenvectors ,Energy (signal processing) ,Numerical stability - Abstract
We present improved calculations of variational energy eigenvalues for the $1{s}^{2}2s {}^{2}S$, $1{s}^{2}3s {}^{2}S$, and $1{s}^{2}2p {}^{2}P$ states of lithium using basis sets with up to 30 224 terms in Hylleraas coordinates. The nonrelativistic energies for infinite nuclear mass are $\ensuremath{-}7.478 060 323 910 143 7(45)$ a.u. for $1{s}^{2}2s {}^{2}S$, $\ensuremath{-}7.354 098 421 444 316 4(32)$ a.u. for $1{s}^{2}3s {}^{2}S$, and $\ensuremath{-}7.410 156 532 651 6(5)$ a.u. for $1{s}^{2}2p {}^{2}P$, which represent the most accurate variational upper bounds to date. An important advantage of the basis sets with multiple distance scales is their exceptional numerical stability.
- Published
- 2011
23. Measurement of the nuclear charge radii of 8,9Li
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W. Nörtershäuser, B. A. Bushaw, A. Dax, G. W. F. Drake, G. Ewald, S. Götte, R. Kirchner, H. -J. Kluge, Th. Kühl, R. Sanchez, A. Wojtaszek, Z. -C. Yan, and C. Zimmermann
- Published
- 2009
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24. Nuclear Charge Radii ofBe7,9,10and the One-Neutron Halo NucleusBe11
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Magda Kowalska, G. W. F. Drake, C. Z. Zimmermann, D. Tiedemann, Z.-C. Yan, J. Krämer, Mark Bissell, Deyan T. Yordanov, A. Krieger, Z. Andjelkovic, C. Geppert, R. Cazan, Klaus Blaum, Rainer Neugart, Wilfried Nörtershäuser, R. Sánchez, M. Zakova, and Ferdinand Schmidt-Kaler
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Physics ,Charge radius ,Nuclear magnetic moment ,General Physics and Astronomy ,Charge density ,Halo nucleus ,Neutron ,Atomic number ,Atomic physics ,Spectroscopy ,Effective nuclear charge - Abstract
Nuclear charge radii of ;{7,9,10,11}Be have been determined by high-precision laser spectroscopy. On-line measurements were performed with collinear laser spectroscopy in the 2s_{1/2}-->2p_{1/2} transition on a beam of Be+ ions. Collinear and anticollinear laser beams were used simultaneously, and the absolute frequency determination using a frequency comb yielded an accuracy in the isotope-shift measurements of about 1 MHz. Combining this with accurate calculations of the mass-dependent isotope shifts yields nuclear charge radii. The charge radius decreases from 7Be to 10Be and then increases for the halo nucleus 11Be. When comparing our results with predictions of ab initio nuclear-structure calculations we find good agreement. Additionally, the nuclear magnetic moment of 7Be was determined to be -1.3995(5)micro_{N} and that of 11Be was confirmed with an accuracy similar to previous beta-NMR measurements.
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- 2009
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25. Chapter 4 Studies of Light Halo Nuclei from Atomic Isotope Shifts
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G.W.F. Drake and Z.-C. Yan
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Physics ,chemistry ,Self-energy ,Atomic theory ,Nuclear structure ,chemistry.chemical_element ,Lithium ,Physics::Atomic Physics ,Electron ,Perturbation theory ,Atomic physics ,Helium ,Effective nuclear charge - Abstract
This paper reviews progress in the application of atomic isotope shift measurements, together with high precision atomic theory, to the determination of nuclear radii from the nuclear volume effect. The theory involves obtaining essentially exact solutions to the nonrelativistic three- and four-body problems for helium and lithium by variational methods. The calculation of relativistic and quantum electrodynamic corrections by perturbation theory is discussed, and in particular, methods for the accurate calculation of the Bethe logarithm part of the electron self energy are presented. The results are applied to the calculation of isotope shifts for the short-lived ‘halo’ nuclei 6He and 11Li in order to determine their nuclear charge radii from high precision spectroscopic measurements. It is shown that the results provide a unique measurement tool that is capable of discriminating amongst a variety of theoretical models for nuclear structure. In view of the high precision that is now obtainable, helium and lithium, along with hydrogen, can be regarded as fundamental atomic systems whose spectra are well understood for all practical purposes.
- Published
- 2008
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26. Studies of light halo nuclei by the isotope shift method
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G. W. F. Drake and Z.-C. Yan
- Published
- 2007
- Full Text
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27. Nuclear charge radii of 9,11Li: the influence of halo neutrons
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R, Sánchez, W, Nörtershäuser, G, Ewald, D, Albers, J, Behr, P, Bricault, B A, Bushaw, A, Dax, J, Dilling, M, Dombsky, G W F, Drake, S, Götte, R, Kirchner, H-J, Kluge, Th, Kühl, J, Lassen, C D P, Levy, M R, Pearson, E J, Prime, V, Ryjkov, A, Wojtaszek, Z-C, Yan, and C, Zimmermann
- Abstract
The nuclear charge radius of 11Li has been determined for the first time by high-precision laser spectroscopy. On-line measurements at TRIUMF-ISAC yielded a 7Li-11Li isotope shift (IS) of 25 101.23(13) MHz for the Doppler-free [FORMULA: SEE TEXT]transition. IS accuracy for all other bound Li isotopes was also improved. Differences from calculated mass-based IS yield values for change in charge radius along the isotope chain. The charge radius decreases monotonically from 6Li to 9Li, and then increases from 2.217(35) to 2.467(37) fm for 11Li. This is compared to various models, and it is found that a combination of halo neutron correlation and intrinsic core excitation best reproduces the experimental results.
- Published
- 2005
28. Nuclear charge radii of 8,9Li determined by laser spectroscopy
- Author
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G, Ewald, W, Nörtershäuser, A, Dax, S, Götte, R, Kirchner, H-J, Kluge, Th, Kühl, R, Sanchez, A, Wojtaszek, B A, Bushaw, G W F, Drake, Z-C, Yan, and C, Zimmermann
- Abstract
The 2s--3s transition of (6,7,8,9)Li was studied by high-resolution laser spectroscopy using two-photon Doppler-free excitation and resonance-ionization detection. Hyperfine structure splittings and isotope shifts were determined with precision at the 100 kHz level. Combined with recent theoretical work, the changes in the nuclear-charge radii of (8,9)Li were determined. These are now the lightest short-lived isotopes for which the charge radii have been measured. It is found that the charge radii monotonically decrease with increasing neutron number from 6Li to 9Li.
- Published
- 2004
29. High-angular-momentum resonances in positron scattering by aHe+ion
- Author
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Z.-C. Yan and Yew Kam Ho
- Subjects
Physics ,Angular momentum ,Positron ,Scattering ,Excited state ,Resonance ,Eigenfunction ,Atomic physics ,Atomic and Molecular Physics, and Optics ,Ion ,Positronium - Abstract
The method of complex-coordinate rotation is applied to investigate resonances in positron scattering by helium ions. Here we present results for high-angular-momentum states $(L=2--6).$ Together with the earlier values for the $L=0$ and 1 states, these stabilized complex eigenvalues exhibit a regular pattern. We also calculate some narrow S-wave resonances below the excited positronium $(N=2)$ threshold. Our converged results for the first S state lying above the ${\mathrm{He}}^{+}$ $(n=5)$ threshold differ substantially from the calculation by Igarashi and Shimamura [Phys. Rev. A 56, 4733 (1997)].
- Published
- 2002
- Full Text
- View/download PDF
30. Application of Energy-Filtered Imaging and HREM in the Study of Terbium Nanoparticles
- Author
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Yong Zhang, George C. Hadjipanayis, Vassil Skumryev, C. E. Nelson, and Z. C. Yan
- Subjects
Materials science ,chemistry ,chemistry.chemical_element ,Nanoparticle ,Terbium ,Nanotechnology ,Instrumentation ,Energy (signal processing) - Published
- 2002
- Full Text
- View/download PDF
31. Magnetic properties of gadolinium and terbium nanoparticles produced via multilayer precursors
- Author
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Christopher T. Nelson, S. Stoyanov, George C. Hadjipanayis, John Q. Xiao, Vassil Skumryev, Z. C. Yan, Yong Zhang, Y. Huang, and Hideyuki Okumura
- Subjects
Nuclear magnetic resonance ,Materials science ,chemistry ,Chemical engineering ,Scanning electron microscope ,Transmission electron microscopy ,Polymer characterization ,Scanning confocal electron microscopy ,Nanoparticle ,Energy filtered transmission electron microscopy ,chemistry.chemical_element ,Terbium ,Superparamagnetism - Abstract
Gd and Tb nanoparticles were obtained via annealing of sputtered multilayer precursors. Detailed structural examination, involving energy-filtered imaging and high-resolution electron microscopy along with transmission electron microscopy and scanning electron microscopy techniques, revealed an island structure for the rare earths within the precursors, which further develops to nanoparticles upon annealing. A dramatic change in the magnetic characteristics of the nanoparticles is observed comparing to the bulk. Magnetic data are discussed to distinguish between true size effects and superparamagnetism. The obtained results give a credit to the former scenario.
32. Critical nuclear charge and shape resonances for the two-electron Hamiltonian.
- Author
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Z-C Yan and Y K Ho
- Published
- 2015
- Full Text
- View/download PDF
33. Colloquium: Laser probing of neutron-rich nuclei in light atoms.
- Author
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Z.-T. Lu, Mueller, P., Drake, G. W. F., Nörtershäuser, W., Pieper, Steven C., and Z.-C. Yan
- Subjects
- *
NEUTRONS , *ATOMS , *NUCLEAR structure , *HELIUM , *ACCURACY - Abstract
The neutron-rich 6He and 8He isotopes exhibit an exotic nuclear structure that consists of a tightly bound 4He-like core with additional neutrons orbiting at a relatively large distance, forming a halo. Recent experimental efforts have succeeded in laser trapping and cooling these short-lived, rare helium atoms and have measured the atomic isotope shifts along the 4He-6He-8He chain by performing laser spectroscopy on individual trapped atoms. Meanwhile, the few-electron atomic structure theory, including relativistic and QED corrections, has reached a comparable degree of accuracy in the calculation of the isotope shifts. In parallel efforts, also by measuring atomic isotope shifts, the nuclear charge radii of lithium and beryllium isotopes have been studied. The techniques employed were resonance ionization spectroscopy on neutral, thermal lithium atoms and collinear laser spectroscopy on beryllium ions. Combining advances in both atomic theory and laser spectroscopy, the charge radii of these light halo nuclei have now been determined for the first time independent of nuclear structure models. The results are compared with the values predicted by a number of nuclear structure calculations and are used to guide our understanding of the nuclear forces in the extremely neutron-rich environment. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
34. Long-range interactions between excited helium and alkali-metal atoms.
- Author
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J.-Y. Zhang, L.-Y. Tang, T.-Y. Shi, Z.-C. Yan, and Schwingenschlög, U.
- Subjects
- *
ALKALI metals , *DISPERSION (Chemistry) , *HELIUM , *UNCERTAINTY , *ATOMS - Abstract
The dispersion coefficients for the long-range interaction of the first four excited states of He, i.e., He(2, 35) and He(2 UP), with the low-lying states of the alkali-metal atoms Li, Na, K, and Rb are calculated by summing over the reduced matrix elements of the multipole transition operators. For the interaction between He and Li the uncertainty of the calculations is 0.1-0.5%. For interactions with other alkali-metal atoms the uncertainty is 1-3% in the coefficient C5, 1-5% in the coefficient C6, and 1-10% in the coefficients C8 and Ci0. The dispersion coefficients C for the interaction of He(2 1,3S) and He(2 1,3P) with the ground-state alkali-metal atoms and for the interaction of He(2 1,3S) with the alkali-metal atoms in their first 2P states are presented in this Brief Report. The coefficients for other pairs of atomic states are listed in the Supplemental Material. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
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