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Gu M, Bai YH, Zhang GP, George TF. Spin-phonon dispersion in magnetic materials. J Phys Condens Matter 2022; 34:375802. [PMID: 35793694 DOI: 10.1088/1361-648x/ac7f17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 07/06/2022] [Indexed: 06/15/2023]
Abstract
Microscopic coupling between the electron spin and the lattice vibration is responsible for an array of exotic properties from morphic effects in simple non magnets to magnetodielectric coupling in multiferroic spinels and hematites. Traditionally, a single spin-phonon coupling constant is used to characterize how effectively the lattice can affect the spin, but it is hardly enough to capture novel electromagnetic behaviors to the full extent. Here, we introduce a concept of spin-phonon dispersion to project the spin moment change along the phonon crystal momentum direction, so the entire spin change can be mapped out. Different from the phonon dispersion, the spin-phonon dispersion has both positive and negative frequency branches even in the equilibrium ground state, which correspond to the spin enhancement and spin reduction, respectively. Our study of bcc Fe and hcp Co reveals that the spin force matrix, that is, the second-order spatial derivative of spin moment, is similar to the vibrational force matrix, but its diagonal elements are smaller than the off-diagonal ones. This leads to the distinctive spin-phonon dispersion. The concept of spin-phonon dispersion expands the traditional Elliott-Yafet theory in nonmagnetic materials to the entire Brillouin zone in magnetic materials, thus opening the door to excited states in systems such as CoF2and NiO, where a strong spin-lattice coupling is detected in the THz regime.
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Affiliation(s)
- Mingqiang Gu
- Department of Physics, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China
| | - Y H Bai
- Office of Information Technology, Indiana State University, Terre Haute, IN 47809, United States of America
| | - G P Zhang
- Department of Physics, Indiana State University, Terre Haute, IN 47809, United States of America
| | - Thomas F George
- Departments of Chemistry & Biochemistry and Physics & Astronomy, University of Missouri-St. Louis, St. Louis, MO 63121, United States of America
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Bai YH, Zhang Z, Li SP. [Impact of co-infection of streptococcus pneumoniae and pneumococcal vaccination on the clinical outcomes of coronavirus disease 19]. Zhonghua Yu Fang Yi Xue Za Zhi 2022; 56:659-667. [PMID: 35644983 DOI: 10.3760/cma.j.cn112150-20211119-01072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Coronavirus disease 19 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 has spread all over the world. Streptococcus pneumoniae as a common pathogen of community-acquired pneumonia shares similar high-risk susceptible populations with COVID-19. Streptococcus pneumoniae co-infection is a key risk factor for severe COVID-19 and death. Pneumococcal vaccination has a beneficial impact on reducing the incidence and mortality of COVID-19. The vaccination rate of streptococcus pneumoniae is still low in China. Streptococcus pneumoniae vaccination may be one of effective strategies in the management of COVID-19 for high-risk population such as the elderly and those who have underlying chronic diseases.
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Affiliation(s)
- Y H Bai
- Department of Biological Products, Chaoyang District Center for Disease Prevention and Control of Beijing, Beijing 100020, China
| | - Z Zhang
- Department of Biological Products, Chaoyang District Center for Disease Prevention and Control of Beijing, Beijing 100020, China
| | - S P Li
- Department of Biological Products, Chaoyang District Center for Disease Prevention and Control of Beijing, Beijing 100020, China
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Bai YH, Li SP, Ding S, Lu Q, Yang LQ, Zhang YL, Zhang JN, Li L, Zhang Z. [Safety analysis of 12 241 infants inoculated in three sites of diphtheria, tetanus, acellular pertussis and haemophilus influenzae type b combined vaccine in Chaoyang District of Beijing]. Zhonghua Yu Fang Yi Xue Za Zhi 2020; 54:953-957. [PMID: 32907284 DOI: 10.3760/cma.j.cn112150-20200316-00342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Objective: To observe the adverse reactions of Diphtheria, Tetanus, Acellular Pertussis and Haemophilus Influenzae Type b Combined Vaccine conjugate vaccine at the anterolateral thigh muscle, upper arm deltoid muscle and upper gluteal region. Methods: A total of 12 241 infants who were voluntarily vaccinated DTaP-Hib from April 2015 to April 2019 in Beijing were selected for the study. DTaP-Hib vaccine is recommended for 3, 4, 5 months of age for basic immunization and 18 to 24 months of age to strengthen immunization. Subjects were divided into the groups of lateral thigh muscle, the upper arm deltoid and upper gluteal region according to the actual inoculation sites. Adverse reactions were collected within 30 minutes and 7 days after each does of vaccination at different sites and compared between three groups. The incidence of adverse reactions at the three different inoculation sites was compared by Chi-square test. Results: A total of 12 241 infants and toddlers received combined DTaP-Hib and 35 027 doses of DTaP-Hib were investigated. The number and of lateral thigh muscles, upper arm deltoids and gluteal muscles were 3 461 infants and 11 129 doses, 2 659 infants and 7 957 doses, 6 121 infants and 15 941 doses respectively. A total of 2 489 adverse reactions occurred. The incidence of adverse reactions was 7.11%. The incidence of adverse reactions in deltoid muscle of upper arm was 9.69%(771 doses), which was higher than that in gluteal muscle (7.58%, 1 211 doses) and anterolateral muscle of thigh (4.56%, 507 doses). The incidence of mild, moderate and severe adverse reactions in the upper arm deltoid group were higher than those in the other two groups. The incidence rates were 4.85% (386 doses), 3.77% (300 doses) and 1.07% (85 doses) respectively. The differences between groups were statistically significant(P<0.001). The total adverse reactions of the three doses of basic immunization and the fourth dose of enhanced immunization had the same trend in different parts. The incidence of adverse reactions was in the order of the upper arm deltoid injection, upper gluteal injection and lateral thigh muscle injection from high to low. The differences were statistically significant (P<0.001). Conclusion: The incidence of adverse reactions of DTaP-Hib vaccination in three different sites was low, which confirmed that the DTaP-Hib vaccination got expected safety regardless of the sites of inoculation. The lateral femoral muscle group had the lowest incidence of adverse reactions, hence it should be preferred as the inoculation site of DTaP-Hib vaccination.
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Affiliation(s)
- Y H Bai
- Department of Biological Products,Chaoyang District Center for Disease Control and Prevention, Beijing 100021, China
| | - S P Li
- Department of Biological Products,Chaoyang District Center for Disease Control and Prevention, Beijing 100021, China
| | - S Ding
- Baotou Medical College, Baotou 014040, China
| | - Q Lu
- Department of Biological Products,Chaoyang District Center for Disease Control and Prevention, Beijing 100021, China
| | - L Q Yang
- Department of Biological Products,Chaoyang District Center for Disease Control and Prevention, Beijing 100021, China
| | - Y L Zhang
- Department of Biological Products,Chaoyang District Center for Disease Control and Prevention, Beijing 100021, China
| | - J N Zhang
- Department of Biological Products,Chaoyang District Center for Disease Control and Prevention, Beijing 100021, China
| | - L Li
- Department of Biological Products,Chaoyang District Center for Disease Control and Prevention, Beijing 100021, China
| | - Z Zhang
- Department of Biological Products,Chaoyang District Center for Disease Control and Prevention, Beijing 100021, China
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Zhang GP, Bai YH, Jenkins T, George TF. Laser-induced ultrafast transport and demagnetization at the earliest time: first-principles and real-time investigation. J Phys Condens Matter 2018; 30:465801. [PMID: 30277218 DOI: 10.1088/1361-648x/aae5a9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
It is generally believed that there are at least two ways to use an ultrafast laser pulse to demagnetize a magnetic sample. One is to directly photo-demagnetize the system through spin-orbit coupling (SOC), and the other is to utilize ultrafast hot electron transport without SOC. The challenge is that these two processes are entangled on the same time scale. While the experimental results have been inconclusive, theoretical investigations are even scarcer, beyond those earlier studies based on spin superdiffusion. For instance, we do not even know how fast electrons move under laser excitation and how far they move. Here we carry out a first-principles time-dependent calculation to investigate how fast electrons actually move under laser excitation and how large the electron transport affects demagnetization on the shortest time scale. To take into account the transport effect, we implement the intraband transition in our theory. In the bulk fcc Ni, we find the effect of the spin transport on the demagnetization is extremely small, no more than 1%. The collective electron velocity in Ni is 0.4 Å fs-1, much smaller than the Fermi velocity, and the collective displacement is no more than 0.1 Å. But this does not mean that electrons do not travel fast; instead we find that electron velocities at two opposite crystal momenta cancel each other. We follow the Γ-X line and find a huge dispersion in the velocities in the crystal momentum space. In the Fe/W(1 1 0) thin film, the overall demagnetization is larger than Ni, and the Fermi velocity is higher than Ni. However, the effect of the spin transport is still small in the Fe/W(1 1 0) thin film. Based on our numerical results and existing experimental findings, we propose a different mechanism that can explain two latest experimental results. Our finding sheds new light on the effect of ballistic transport on demagnetization.
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Affiliation(s)
- G P Zhang
- Department of Physics, Indiana State University, Terre Haute, IN 47809, United States of America
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Zhang GP, Si MS, Murakami M, Bai YH, George TF. Generating high-order optical and spin harmonics from ferromagnetic monolayers. Nat Commun 2018; 9:3031. [PMID: 30072711 PMCID: PMC6072758 DOI: 10.1038/s41467-018-05535-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 07/05/2018] [Indexed: 11/08/2022] Open
Abstract
High-order harmonic generation (HHG) in solids has entered a new phase of intensive research, with envisioned band-structure mapping on an ultrashort time scale. This partly benefits from a flurry of new HHG materials discovered, but so far has missed an important group. HHG in magnetic materials should have profound impact on future magnetic storage technology advances. Here we introduce and demonstrate HHG in ferromagnetic monolayers. We find that HHG carries spin information and sensitively depends on the relativistic spin-orbit coupling; and if they are dispersed into the crystal momentum k space, harmonics originating from real transitions can be k-resolved and carry the band structure information. Geometrically, the HHG signal is sensitive to spatial orientations of monolayers. Different from the optical counterpart, the spin HHG, though probably weak, only appears at even orders, a consequence of SU(2) symmetry. Our findings open an unexplored frontier-magneto-high-order harmonic generation.
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Affiliation(s)
- G P Zhang
- Department of Physics, Indiana State University, Terre Haute, IN, 47809, USA.
| | - M S Si
- Key Lab for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou, 730000, China
| | - M Murakami
- Department of Physics, Indiana State University, Terre Haute, IN, 47809, USA
| | - Y H Bai
- Office of Information Technology, Indiana State University, Terre Haute, IN, 47809, USA
| | - Thomas F George
- Office of the Chancellor Departments of Chemistry & Biochemistry, Physics & Astronomy University of Missouri-St. Louis, St. Louis, MO, 63121, USA
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Han Y, Bai YH, Hou XM. [Glide path management of rotary nickel-titanium instruments in simulated root canals]. Beijing Da Xue Xue Bao Yi Xue Ban 2018; 50:148-153. [PMID: 29483738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
OBJECTIVE To compare the shaping ability of ProGlider, HyFlex EDM Glidepath File and RaCe ISO 10 with that of PathFile and stainless steel K-file hand instruments in simulated root canals. METHODS A total of 60 simulated resin blocks were divided randomly into five groups (n=12), each group prepared with each instrument, respectively. Preparation time was recorded. Pre- and post-operative images were obtained using a scanner and superimposed using Photoshop. The material removal from the inner and outer canal walls beginning from 0 mm at the end point of the canal were measured using ImageJ. Centering ability was determined, accordingly. The data were analyzed using the One-Way ANOVA at a significance level of P<0.05. RESULTS Preparation time for ProGlider was (61.018±5.020) s, significantly the fastest (P < 0.05), that for SS K-file (111.100±6.987) s, the slowest (P<0.05), and the differences among the other 3 groups were not significant (P>0.05). The removal of resin from the outer wall at the apical portion was significantly lower for HyFlex EDM Glidepath File than for ProGlider (P<0.05), both of them were significantly lower than the other 3 groups (P<0.05). For the removal from the inner wall at the curvature portion, ProGlider was the least whilst SS K-file the most (P<0.05). At the straight portion, RaCe ISO 10 removed the most not only from the inner but also the outer wall (P<0.05), HyFlex EDM Glidepath File the second most, and the other 3 groups among the same levels. As far as the centering ability was concerned, at the apical portion, HyFlex EDM Glidepath File was the best, ProGlider the second best, no significant difference identified among the other 3 groups. At the curvature portion, ProGlider and HyFlex EDM Glidepath File were the best, PathFile the second, RaCe ISO 10 the third, the worst was the SS K-file. At the straight portion, the difference amongt the 5 groups was not significant. CONCLUSION The shaping abilities of ProGlider, HyFlex EDM Glidepath File and RaCe ISO 10 were better or comparable to that of PathFile, while the preparation time for ProGlider reduced significantly, and HyFlex EDM Glidepath File and RaCe ISO 10 removed significantly more resin at the straight portion of the canal.
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Affiliation(s)
- Y Han
- Second Dental Center, Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing 100101, China
| | - Y H Bai
- Department of Stomatology, Xuanwu Hospital, Capital Medical University, Beijing 100053, China
| | - X M Hou
- Second Dental Center, Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing 100101, China
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Zhang GP, Jenkins T, Bennett M, Bai YH. Manifestation of intra-atomic 5d6s-4f exchange coupling in photoexcited gadolinium. J Phys Condens Matter 2017; 29:495807. [PMID: 29105644 DOI: 10.1088/1361-648x/aa986c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Intra-atomic exchange couplings (IECs) between 5d6s and 4f electrons are ubiquitous in rare-earth metals and play a critical role in spin dynamics. However, detecting them in real time domain has been difficult. Here we show the direct evidence of IEC between 5d6s and 4f electrons in gadolinium. Upon femtosecond laser excitation, 5d6s electrons are directly excited; their majority bands shift toward the Fermi level while their minority bands do the opposite. For the first time, our first-principles minority shift now agrees with the experiment quantitatively. Excited 5d6s electrons lower the exchange potential barrier for 4f electrons, so the 4f states are also shifted in energy, a prediction that can be tested experimentally. Although a significant number of 5d6s electrons, some several eV below the Fermi level, are excited out of the Fermi sea, there is no change in the 4f states, a clear manifestation of intra-atomic exchange coupling.
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Affiliation(s)
- G P Zhang
- Department of Physics, Indiana State University, Terre Haute, IN 47809, United States of America
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Zhang GP, Bai YH, George TF. Is perpendicular magnetic anisotropy essential to all-optical ultrafast spin reversal in ferromagnets? J Phys Condens Matter 2017; 29:425801. [PMID: 28770812 DOI: 10.1088/1361-648x/aa83c6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
All-optical spin reversal presents a new opportunity for spin manipulations, free of a magnetic field. Most of all-optical-spin-reversal ferromagnets are found to have a perpendicular magnetic anisotropy (PMA), but it has been unknown whether PMA is necessary for spin reversal. Here we theoretically investigate magnetic thin films with either PMA or in-plane magnetic anisotropy (IMA). Our results show that spin reversal in IMA systems is possible, but only with a longer laser pulse and within a narrow laser parameter region. Spin reversal does not show a strong helicity dependence where the left- and right-circularly polarized light lead to the identical results. By contrast, the spin reversal in PMA systems is robust, provided both the spin angular momentum and laser field are strong enough while the magnetic anisotropy itself is not too strong. This explains why experimentally the majority of all-optical spin-reversal samples are found to have strong PMA and why spins in Fe nanoparticles only cant out of plane. It is the laser-induced spin-orbit torque that plays a key role in the spin reversal. Surprisingly, the same spin-orbit torque results in laser-induced spin rectification in spin-mixed configuration, a prediction that can be tested experimentally. Our results clearly point out that PMA is essential to spin reversal, though there is an opportunity for in-plane spin reversal.
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Affiliation(s)
- G P Zhang
- Department of Physics, Indiana State University, Terre Haute, IN 47809, United States of America
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Su Z, Bai YH, Hou XM. [Effects of different techniques on removal of vapor lock in the apical region of curved canals: a cone-beam computed tomography study]. Beijing Da Xue Xue Bao Yi Xue Ban 2017; 49:76-80. [PMID: 28203008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
OBJECTIVE To compare the effect of four different techniques on removal of vapor lock in the apical region of curved root canals. METHODS Forty simulated resin root canals with 45° curvature were prepared using WaveOne Primary, then the apical foramen were sealed with soft wax. The teeth were divided randomly into 4 groups thereafter (n=10). Contract solution was injected into the canals using a 30 G side-vented needle and scanned with cone-beam CT (CBCT) to identify the volume of the vapor lock. Four different techniques including photon-induced photoacoustic streaming (PIPS) laser-activated irrigation, gutta-percha cone technique, ultrasonic irrigation, and sonic irrigation were used to remove the vapor locks in the root canals. The residual volume of the vapor lock was identified again using CBCT scanning data. Accordingly, the reduction rates of the vapor lock were calculated. Furthermore, the initial and residual vapor lock length was calculated. The data were analyzed by using the One-way ANOVA analysis and Kruskal-Wallis H test at a significance level of P<0.05. RESULTS There was no significant difference in the initial vapor lock volume (P>0.05). Residual volume of the vapor lock for PIPS laser-activated irrigation was 0 mm(3), and that for gutta-percha cone technique was (0.02±0.07) mm3, significantly lower than those of ultrasonic and sonic irrigation, the values being (0.20±0.09) mm(3) and (0.23±0.06) mm(3) (P<0.001), respectively. The reduction rates of the vapor lock of PIPS laser-activated irrigation and gutta-percha cone technique were 100.00% (100.00%, 100.00%) and 100.00% (77.66%, 100.00%), respectively, significantly higher than those of ultrasonic irrigation [70.37% (56.41%, 91.43%)] and sonic irrigation [63.54% (51.47%, 74.00%), P<0.001]. The length of the residual vapor lock for PIPS laser-activated irrigation was 0 mm, and that for gutta-percha cone technique was (0.15±0.47) mm, significantly lower than those of ultrasonic and sonic irrigation, values being (2.21±0.09) mm and (2.34±0.08) mm (P<0.001), respectively. The length of the residual vapor locks in the ultrasonic and sonic group remained approximately the same as the distance between the working tip and the apical foramen. CONCLUSION PIPS laser activated irrigation and gutta-percha cone technique could remove the vapor lock from the apical region of curved canals effectively.
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Affiliation(s)
- Z Su
- Department of Endodontics, Capital Medical University School of Stomatology, Beijing 100050, China
| | - Y H Bai
- Department of Stomatology, Xuanwu Hospital, Capital Medical University, Beijing 100053, China
| | - X M Hou
- The Second Dental Center, Peking University School and Hospital of Stomatology & National Engineering Laboratory for Digital and Material Technology of Stomatology & Beijing Key Laboratory of Digital Stomatology, Beijing 100101, China
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Li HY, Liu YC, Bai YH, Sun M, Wang L, Zhang XB, Cai B. SNP at miR-483-5p-binding site in the 3'-untranslated region of the BSG gene is associated with susceptibility to esophageal cancer in a Chinese population. Genet Mol Res 2016; 15:gmr7735. [PMID: 27420938 DOI: 10.4238/gmr.15027735] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The aim of this study was to investigate the association between a functional variant of the basigin (BSG) gene, caused by a polymorphism (rs11473) at the miR-483-5p binding site, and the risk of esophageal squamous cell carcinoma (ESCC) in the Chinese population. The rs11473 polymorphism was genotyped in 624 esophageal cancer patients and 636 cancer-free age- and gender-matched controls using polymerase chain reaction restriction and direct sequencing. The functional variants resulting from the BSG rs11473 SNP were investigated using a luciferase activity assay and validated by immunoblotting. We discovered that ESCC patients carrying the rs11473 AA genotype or A allele were at a significantly higher risk of esophageal cancer [odds ratio (OR) = 1.560, 95% confidence interval (CI) = 1.031-2.358, P = 0.037; OR = 1.231, 95%CI = 1.038-1.459, P = 0.017, respectively] than those carrying the GG genotype and G allele. Moreover, the rs11473 polymorphism modifies the binding of miR-483- 5p to basigin, as well as the basigin protein levels in esophageal cancer patients. Our data suggested that the rs11473 polymorphism at the miR- 483-5p binding site in the 3'-UTR of basigin gene may play a key role in the development of esophageal cancer in a Chinese population.
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Affiliation(s)
- H Y Li
- Department of Clinical Laboratory, Baoji People's Hospital, Baoji, Shanxi, China
| | - Y C Liu
- Department of Oncology, Taixing People's Hospital, Taixing, Jiangsu, China
| | - Y H Bai
- Department of Clinical Laboratory, Baoji People's Hospital, Baoji, Shanxi, China
| | - M Sun
- Department of Clinical Laboratory, Baoji People's Hospital, Baoji, Shanxi, China
| | - L Wang
- Department of Clinical Laboratory, Baoji People's Hospital, Baoji, Shanxi, China
| | - X B Zhang
- Department of Clinical Laboratory, Baoji People's Hospital, Baoji, Shanxi, China
| | - B Cai
- Department of Clinical Laboratory, Taixing People's Hospital, Taixing, Jiangsu, China
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Abstract
A decade ago Rhie et al (2003 Phys. Rev. Lett. 90 247201) reported that when ferromagnetic nickel is subject to an intense ultrashort laser pulse, its exchange splitting is reduced quickly. But to simulate such reduction remains a big challenge. The popular rigid band approximation (RBA), where both the band structure and the exchange splitting are held fixed before and after laser excitation, is unsuitable for this purpose, while the time-dependent density functional theory could be time-consuming. To overcome these difficulties, we propose a time-dependent Liouville and density functional theory (TDLDFT) that integrates the time-dependent Liouville equation into the density functional theory. As a result, the excited charge density is reiterated back into the Kohn-Sham equation, and the band structure is allowed to change dynamically. Even with the ground-state density functional, a larger demagnetization than RBA is found; after we expand Ortenzi's spin scaling method into an excited-state (laser) density functional, we find that the exchange splitting is indeed strongly reduced, as seen in the experiment. Both the majority and minority bands are shifted toward the Fermi level, but the majority shifts a lot more. The ultrafast reduction in exchange splitting occurs concomitantly with demagnetization. While our current theory is still unable to yield the same percentage loss in the spin moment as observed in the experiment, it predicts a correct trend that agrees with the experiments. With a better functional, we believe that our results can be further improved.
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Affiliation(s)
- G P Zhang
- Department of Physics, Indiana State University, Terre Haute, IN 47809, USA
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Zhang GP, Si MS, Bai YH, George TF. Magnetic spin moment reduction in photoexcited ferromagnets through exchange interaction quenching: beyond the rigid band approximation. J Phys Condens Matter 2015; 27:206003. [PMID: 25950828 DOI: 10.1088/0953-8984/27/20/206003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The exchange interaction among electrons is one of the most fundamental quantum mechanical interactions in nature and underlies any magnetic phenomena from ferromagnetic ordering to magnetic storage. The current technology is built upon a thermal or magnetic field, but a frontier is emerging to directly control magnetism using ultrashort laser pulses. However, little is known about the fate of the exchange interaction. Here we report unambiguously that photoexcitation is capable of quenching the exchange interaction in all three 3d ferromagnetic metals. The entire process starts with a small number of photoexcited electrons which build up a new and self-destructive potential that collapses the system into a new state with a reduced exchange splitting. The spin moment reduction follows a Bloch-like law as M(z)(ΔE) = M(z)(0)(1 - ΔE/ΔE₀)(1/β), where ΔE is the absorbed photon energy and β is a scaling exponent. A good agreement is found between the experimental and our theoretical results. Our findings may have a broader implication for dynamic electron correlation effects in laser-excited iron-based superconductors, iron borate, rare-earth orthoferrites, hematites and rare-earth transition metal alloys.
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Affiliation(s)
- G P Zhang
- Department of Physics, Indiana State University, Terre Haute, IN 47809, USA
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Abstract
A 25-year-old male weightlifter felt increasing intractable low back pain during training but denied any acute injury. The physical examination, blood parameters, radiographs and MRI were unremarkable. He had been treated non-operatively by various means, with only temporary relief. The pressures in the lumbar paraspinal compartment were abnormally high and he was treated by surgical decompression. This gave rapid relief, he returned to training, and one year later the pain had not recurred.
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Affiliation(s)
- Y M Xu
- Shanghai Sixth People's Hospital Shanghai JiaoTong University, Shanghai, China
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Wang TL, Zhou C, Shen YW, Wang XY, Ding XL, Tian S, Liu Y, Peng GH, Xue SQ, Zhou JE, Wang RL, Meng XM, Pei GD, Bai YH, Liu Q, Li H, Zhang JZ. Prevalence of androgenetic alopecia in China: a community-based study in six cities. Br J Dermatol 2010; 162:843-7. [PMID: 20105167 DOI: 10.1111/j.1365-2133.2010.09640.x] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- T L Wang
- Department of Dermatology, Peking University People's Hospital, Beijing 100044, China
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Xu YM, Bai YH, Li QT, Yu H, Cao ML. Chronic lumbar paraspinal compartment syndrome: a case report and review of the literature. J Bone Joint Surg Br 2009. [PMID: 19949129 DOI: 10.1302/0301-620x.91b12.22647.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A 25-year-old male weightlifter felt increasing intractable low back pain during training but denied any acute injury. The physical examination, blood parameters, radiographs and MRI were unremarkable. He had been treated non-operatively by various means, with only temporary relief. The pressures in the lumbar paraspinal compartment were abnormally high and he was treated by surgical decompression. This gave rapid relief, he returned to training, and one year later the pain had not recurred.
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Affiliation(s)
- Y M Xu
- Shanghai Sixth People's Hospital Shanghai JiaoTong University, Shanghai, China
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Cheng YL, Yan M, Li JL, Liu ZR, Bai YH, Tian W, Wu DG, Cheng Q. Variations in indoor PM10 concentrations in sixteen homes in Guiyang City, People's Republic of China. Bull Environ Contam Toxicol 2006; 77:112-8. [PMID: 16832763 DOI: 10.1007/s00128-006-1039-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Accepted: 05/11/2006] [Indexed: 05/10/2023]
Affiliation(s)
- Y L Cheng
- College of Environmental Sciences, Peking University, Beijing 100871, People's Republic of China
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Bai YH, Takemitsu M, Atsuta Y, Matsuno T. Peripheral mononeuropathy induced by loose ligation of the sciatic nerve in the rat: behavioral, electrophysiological and histopathologic studies. Exp Anim 1999; 48:87-94. [PMID: 10374069 DOI: 10.1538/expanim.48.87] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The relationship between clinical parameters and pathological changes was investigated in an animal model of mononeuropathy, by behavioral, electrophysiological and histopathological methods. Mononeuropathy was induced in rats by loosely tying ligatures around the sciatic nerve. Eighty-four rats were used, and these were divided into fourteen groups to determine chronological changes in the withdrawal reflex latency, nerve conduction velocity and ultrastructure of the nerve from 1 to 84 days after nerve ligation surgery. Pathological changes around the ligated nerves were divisible in three phases: the first week was an inflammatory phase, when axonal degeneration, phagocyte infiltration and interstitial edematous changes were observed. The second and third weeks were a nerve-sprouting phase, when numerous axonal sprouts and remyelination were seen. The fourth to twelfth weeks were a recovery phase in which maturing myelination and interstitial fibrosis were characteristic. In the inflammatory phase, withdrawal reflex latencies were shortened, and sensory nerve conduction velocities (SCV) and motor nerve conduction velocities (MCV) gradually decreased. In the nerve-sprouting phase, the latency values remained low, and SCV and MCV were minimal. The parameters examined gradually returned to control levels during the recovery phase. In conclusion, these findings increase the knowledge of disease progression in mononeuropathy with hyperalgesia in human and animal models.
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Affiliation(s)
- Y H Bai
- Department of Orthopaedic Surgery, Asahikawa Medical College, Hokkaido, Japan
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Abstract
: To elucidate the pathogenesis of chronic compartment syndrome, we examined pathological changes in the soleus (red) and extensor digitorum longus (EDL; white) muscles in Japanese white rabbits after repeated compression with a pneumatic tourniquet. Repeated tourniquet compression via cuff inflation was carried out on the rabbits, calves daily, for 2 h, then stopped for 30 min, and then applied for another 2 h. The contralateral hindlimb, which was not compressed, served as a control. Animals were allocated to 15 groups, with pressures of 40, 80, and 120 mmHg for periods of 1 day, 3 days, 1 week, 2 weeks, and 4 weeks. Skeletal muscle specimens in each group were studied by histopathological and histochemical (ATPase) methods. After compression for 1 day, regardless of pressure, and compression for 3 days in the 40-mmHg pressure group, edematous changes in regions with mild inflammation and increases in fiber diameter were observed in the muscles. After compression for 3 days in the 80- and 120-mmHg pressure groups, and after 1, 2, or 4 weeks in the 40-mmHg pressure group, a few necrotic fibers and scattered fibers with some mononuclear cell infiltrates indicative of early-stage necrosis were detected. In the groups with 80 or 120 mmHg pressure for 1, 2, or 4 weeks, muscle fibers exhibited marked degenerative changes, which were more pronounced in the 120-mmHg group than in the 80-mmHg group. The pathological changes were more pronounced in the soleus than in the EDL muscles, indicating that these two muscles differed in sensitivity to repeated compression. Additionally, average muscle wet weight and average fiber diameter for both types of muscle were increased in the 1-day and 3-day compression groups and decreased in the 1-week, 2-week, and 4-week compression groups. These findings clearly differ from those of previously reported single-compression experiments. Our findings indicate that repeated compression may cause serious muscle degeneration, particularly in red muscles.
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Affiliation(s)
- Y H Bai
- Department of Orthopaedic Surgery, Asahikawa Medical College, Nishikagura 4-5, 3-11, Asahikawa, Hokkaido 078-8510, Japan
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Ma DC, Sun YH, Chang KZ, Ma XF, Huang SL, Bai YH, Kang J, Liu YG, Chu JJ. Selective induction of apoptosis of NB4 cells from G2+M phase by sodium arsenite at lower doses. Eur J Haematol Suppl 1998; 61:27-35. [PMID: 9688289 DOI: 10.1111/j.1600-0609.1998.tb01057.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Apoptosis of NB4 cells induced by sodium arsenite and arsenate was studied using flow cytometry and DNA gel electrophoresis in order to investigate their effects on cell cycle and determine the relationship between apoptosis and cell cycle. In this study, we found that: 1) at low doses, sodium arsenite selectively induced apoptosis of NB4 cells in G2+M phase of cell cycle after its being arrested in G2 phase. With increment of the cells blocked in G2 phase, dUTP-specifically labeling cells in G2+M phase increased without concomitant increment of dUTP-labeling cells in other two phases of cell cycle; 2) at high doses, extensive apoptosis was induced in NB4 cells from all phases of cell cycle without cell cycle preference and cell cycle blockade; 3) sodium arsenite-induced apoptosis of NB4 cells occurred in the presence of bcl-2 expression as the unapoptotic cells; 4) sodium arsenite with As3+ induced apoptosis of NB4 cells more strongly than sodium arsenate with As5+ did although both of them affected NB4 cells in the same pattern. These results not only suggested that both arsenite and arsenate induced apoptosis of NB4 cells through 2 different mechanisms--at low doses, arsenical might directly induce apoptosis through regulation of cell cycle checkpoint, while at high doses they might directly induce it, but also indicated that bcl-2 might not play an important role in arsenite or arsenate-induced apoptosis of NB4 cells, whereas chemical valence of As in a compound might be related to efficiency in arsenical induction of apoptosis.
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Affiliation(s)
- D C Ma
- Department of Experimental Medicine, Northern Hospital, Shenyang, Liaoning, China
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Bai YH, Wang DW, Cui XM, Long JY, Cui CB, Jia CY, Song LW. Expression of transforming growth factor beta in radiation interstitial pneumonitis. J Environ Pathol Toxicol Oncol 1997; 16:15-20. [PMID: 9256927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We investigated the changes in transforming growth factor beta 1 (TGF-beta 1) mRNA and TGF-beta 3 protein expression that occur in radiation interstitial pneumonitis. We used TGF-beta 1-cDNA probe in situ hybridization and TGF-beta 3 polyclonal antibody in immunohistochemical techniques. Our results showed that the distribution of TGF-beta 1 mRNA and TGF-beta 3 protein basically coincided in blood vessels, airways, lung parenchyma, and alveolar macrophages. However, bronchial epithelial cells expressed only TGF-beta 3 proteins and no TGF-beta 1 mRNA. We found an increased expression of TGF-beta 1 mRNA and TGF-beta 3 proteins in radiation interstitial pneumonitis.
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Affiliation(s)
- Y H Bai
- Department of Experimental Pathology, Institute of Radiation Medicine, Beijing, P.R. China
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Abstract
Gs and adenylate cyclase from bovine brain cortices were co-reconstituted into asolectin liposomes with or without 1000-fold transmembrane Ca2+ gradient. Obtained results showed that Gs activities of both binding GTP gamma S and stimulating adenylate cyclase were the highest in proteoliposomes, with a transmembrane Ca2+ gradient similar to the physiological situation and the lowest while the transmembrane Ca2+ gradient was in the inverse direction. Such a difference could be diminished following the dissipation of the transmembrane Ca2+ gradient by A23187. Time-resolved fluorescence anisotropy of diphenylhexatriene (DPH) has been used to compare the physical state of phospholipids among those proteoliposomes. It is suggested that a proper transmembrane Ca2+ gradient is essential for higher membrane fluidity, which may favor Gs function with higher GTP-binding activity and stimulation of adenylate cyclase.
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Affiliation(s)
- G F Fan
- National Laboratory of Biomacromolecules, Chinese Academy of Sciences, Beijing
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Bai YH, Wang DW, Wang LP, Chen JZ, Yang Y. The role of free radicals in the development of radiation interstitial pneumonitis. J Environ Pathol Toxicol Oncol 1993; 12:199-204. [PMID: 8189375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We examined the morphologic changes in the lung tissue of Wistar rats after chest irradiation and determined sequentially the content of free radicals (FR) using electron spin resonance. The activity of superoxide dismutase (SOD) was also assessed using the chemical glow method of xanthine oxidase. After chest irradiation, the content of FR in the lung progressively increased and the activity of SOD progressively decreased. We discuss here the role of the FR in the developing process of radiation interstitial pneumonitis.
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Affiliation(s)
- Y H Bai
- Department of Experimental Pathology, Academy of Military Medical Science, Beijing, China
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