Publications by authors named "Peifang Li"

23 Publications

  • Page 1 of 1

Structural basis for zinc-induced activation of a zinc uptake transcriptional regulator.

Nucleic Acids Res 2021 06;49(11):6511-6528

State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi Key Laboratory for Sugarcane Biology, Guangxi University, Nanning 530004, China.

The zinc uptake regulator (Zur) is a member of the Fur (ferric uptake regulator) family transcriptional regulators that plays important roles in zinc homeostasis and virulence of bacteria. Upon zinc perception, Zur binds to the promoters of zinc responsive genes and controls their transcription. However, the mechanism underlying zinc-mediated Zur activation remains unclear. Here we report a 2.2-Å crystal structure of apo Zur from the phytopathogen Xanthomonas campestris pv. campestris (XcZur), which reveals the molecular mechanism that XcZur exists in a closed inactive state before regulatory zinc binding. Subsequently, we present a 1.9-Å crystal structure of holo XcZur, which, by contrast, adopts an open state that has enough capacity to bind DNA. Structural comparison and hydrogen deuterium exchange mass spectrometry (HDX-MS) analyses uncover that binding of a zinc atom in the regulatory site, formed by the hinge region, the dimerization domain and the DNA binding domain, drives a closed-to-open conformational change that is essential for XcZur activation. Moreover, key residues responsible for DNA recognition are identified by site-directed mutagenesis. This work provides important insights into zinc-induced XcZur activation and valuable discussions on the mechanism of DNA recognition.
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http://dx.doi.org/10.1093/nar/gkab432DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8216289PMC
June 2021

The comparison between total hip arthroplasty and hemiarthroplasty in patients with femoral neck fractures: a systematic review and meta-analysis based on 25 randomized controlled trials.

J Orthop Surg Res 2020 Dec 10;15(1):596. Epub 2020 Dec 10.

West China School of Nursing, Sichuan University/Department of Orthopedics, West China Hospital, Sichuan University, Chengdu, 610041, People's Republic of China.

Background: We performed an updated systematic review and meta-analysis which enrolled 25 prospective randomized controlled trials (RCTs) to compare the outcomes between total hip arthroplasty (THA) and hemiarthroplasty (HA) in patients with femoral neck fractures (FNFs).

Methods: We searched English databases which included PubMed, Embase (vis OvidSP), The Cochrane Library, and Web of Science, and Chinese databases Chinese National Knowledge Infrastructure (CNKI), VIP, Wang Fang, and China Biology Medicine Disc (CBM) in July 2020. The quality of each study was assessed according to the Cochrane Collaboration's Risk of Bias. Risk ratios (RRs) and weighted mean differences (WMDs) with 95% confidence intervals (95% CIs) were pooled with random-effects models. Data regarding baseline characteristics, hospital and surgery outcomes, clinical outcomes, patients' quality of life, common complications, prothesis-related complications, mortality, and costs were reported.

Results: A total of 25 RCTs involving 3223 patients (1568 THA and 1655 HA) were included. THA had longer hospital length (WMD = 0.721, P < 0.0001) and surgery time (WMD = 20.044, P < 0.0001), and more blood loss compared with HA (WMD = 69.109, P < 0.0001). THA showed better ratings in the Harris Hip Score during follow-up periods between 1 and 5 years while no differences within 6 months and after 9 years. THA was associated with higher quality-of-life EuroQol-5 Dimension (EQ-5D) scores after 2 years of surgery but no difference within 1 year. There was no difference in common complications. THA had significant higher rate of dislocation (WMD = 1.897, P = 0.002) and lower acetabular erosion (WMD = 0.030, P = 0.001). For mortality, there was no difference during all the follow-up periods except for slightly higher 2-year mortality after surgery.

Conclusion: This meta-analysis demonstrates that THA has better medium-term functional results and quality of life and lower acetabular erosion rate, while HA shows better in reducing hospital stay, surgery time, and blood loss and also has lower dislocation rate.
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http://dx.doi.org/10.1186/s13018-020-02122-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7730787PMC
December 2020

High-pressure crystal structure and properties of BrCl.

J Phys Condens Matter 2020 Mar;33(9):095401

College of Mathematics and Physics, Inner Mongolia University for Nationalities, Tongliao 028043, People's Republic of China.

The pressure-induced phase transitions of bromine chloride (BrCl) were studied using the CALYPSO structure prediction method and first-principles calculations. Geometry optimization showed that the BrCl underwent the following phase transitions under high pressure: Cmcm → C2/m → Fddd → P4/mmm. These phase transitions occurred at 75, 94, and 140 GPa, respectively. All four phases were calculated to be dynamically stable, judging by the absence of any imaginary phonon modes in the whole Brillouin zone. As the pressure increased, the number of bonds between Br atom and surrounding Cl atoms increased. The high-pressure P4/mmm-BrCl phase (stable at 150 GPa) consisted of eight-coordinated Br atoms and is predicted to exist in BrCl compounds for the first time. The band overlap of the Cmcm phase, which caused the pressure-induced semiconductor → metal transition, occurs ∼50 GPa. This article lays the foundation for further theoretical and experimental research.
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http://dx.doi.org/10.1088/1361-648X/abcc10DOI Listing
March 2020

The Effect of Chitosan in Wound Healing: A Systematic Review.

Adv Skin Wound Care 2021 May;34(5):262-266

At the West China School of Nursing/West China Hospital Orthopedics Department, Sichuan University, Chengdu, China, Ying Liu, MS, is a master's student; JiaLi Chen, MS, RN, is Co-chief Superintendent Nurse and International Wound Therapist; PeiFang Li, MSN, RN, is Senior Nurse and International Wound Therapist; and Ning Ning, MS, RN, is Chief Nurse and Professor. The authors have disclosed no financial relationships related to this article. Submitted February 7, 2020; accepted in revised form April 20, 2020; published online ahead of print November 16, 2020.

Objective: To systematically review the effectiveness of chitosan in wound healing.

Data Sources: References were retrieved from PubMed, EMBASE, the Cochrane library, and Web of Science based on Medical Subject Headings and keywords ("chitosan" OR "chitin" OR "poliglusam" AND "wound healing").

Study Selection: Eligible articles were randomized controlled trials (RCTs) that required interventions for chitosan and its derivative dressings and included endpoints associated with wound healing. In summary, five RCTs (N = 319) were included in the final analysis.

Data Synthesis: Only two RCTS (40%) reported significant beneficial effects of chitosan on wound healing compared with conventional gauze dressings (eg, tulle gras, petroleum jelly). The remaining three studies reported that chitosan had no significant effect on clinical wound healing compared with other biologic dressings (eg, alginate, hydrocolloid).

Conclusions: Although the number of trials of new chitosan dressings has been increasing, studies on the relationship between chitosan and wound healing have been limited. Current data suggest that chitosan does not slow wound healing. However, the small number of available trials restricted adequate interpretation of the existing results. Future research needs to be rigorously designed to confirm any clinically relevant effect of chitosan in wound healing.
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http://dx.doi.org/10.1097/01.ASW.0000723128.58588.b5DOI Listing
May 2021

[Urgent recommendation protective measures of West China Hospital for medical personnel to prevent device related pressure injuries in 2019-nCoV epidemic situation].

Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi 2020 Aug;34(8):1036-1040

Department of Orthopedics, West China Hospital, Sichuan University, Chengdu Sichuan, 610041, P.R.China.

At present, the 2019-nCoV epidemic situation is in severe and complex period. In order to prevent the virus from invading and infecting, it is very important and urgent for medical personnel to protect themselves. However, in the process of using protective equipment by medical personnel, the performance of device related pressure injuries (DRPI) caused by pain, numbness, redness, and even breakage caused by the equipment has seriously endangered the health of medical personnel. This article, based on Prevention and Treatment of Pressure Ulcers/Injuries: Quick Reference Guide 2019, references, and clinical experiences of wound specialists in West China Hospital of Sichuan University, summarize the preventive and protective measures of West China Hospital for medical personnel to prevent DRPI, so as to provide clinical preventive measurements for medical personnel.
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http://dx.doi.org/10.7507/1002-1892.202002009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8171919PMC
August 2020

Crystal structure and properties of iodine monofluoride compounds at high pressure.

J Phys Condens Matter 2020 May 20;32(38):385404. Epub 2020 May 20.

College of Mathematics and Physics, Inner Mongolia University for Nationalities, Tongliao 028000, People's Republic of China.

The pressure-induced structural phase transitions of halogen compound IF under high pressure were studied by using the unbiased CALYPSO structure prediction method. The phase transition sequence of IF under high pressure is determined to be P1 → P2/c-I → P2/c-II → I4/mmm, and the corresponding phase transition pressures are 3 GPa, 16.5 GPa and 46 GPa, respectively. The physical properties of each predicted phase were thus fully studied, and it was found that the P1 phase was unstable which is in excellent agreement with the experiment result. Furthermore, our exploration of the high pressure phases for IF will provide fundamental insights for further exploration the structural phase transition of other halogen compounds under high pressure.
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http://dx.doi.org/10.1088/1361-648X/ab94f5DOI Listing
May 2020

Subtypes of anterior circulation large artery occlusions with acute brain ischemic stroke.

Sci Rep 2020 02 26;10(1):3442. Epub 2020 Feb 26.

Department of Neurology, The Second Hospital of Hebei Medical University, 215 West Heping Road, Shijiazhuang, Hebei, 050000, China.

Anterior circulation large artery occlusion (AC-LAO) related acute ischemic stroke (AIS) is particularly common in clinics in China. We retrospectively analyzed 787 consecutively hospitalized AIS patients with AC-LAO in Hebei Province, China. AC-LAO was defined as a complete occlusion of at least one intracranial internal carotid artery (ICA) or middle cerebral artery (MCA) based on computed tomography or magnetic resonance angiography. Among eight subtypes of AC-LAO, unilateral MCA occlusion is the most common one (49.8%, n = 392), while bilateral ICA/unilateral MCA occlusion is the least (0.3%, n = 2). Compared with unilateral MCA and unilateral ICA occlusion, patients with tandem ICA/MCA and bilateral ICA/MCA occlusion had poor outcomes after suffering AIS. Age (OR 1.022; 95%CI, 1.007 to 1.036) was an independent risk factor for single artery progressed to multiple artery occlusion, while ApoA1 (OR 0.453; 95% CI, 0.235 to 0.953) was a protective factor. Patients with unilateral MCA occlusion were prone to artery-to-artery embolism infarction subtype, unilateral ICA occlusion group were the most vulnerable to hypoperfusion/impaired emboli clearance subtype. Our results suggested various AC-LAO subtypes have different clinical characteristics and prognosis and were prone to different subtypes of infarction. Customized preventive measures based on AC-LAO subtypes may be more targeted preventions of stroke recurrences for AIS patients and could improve their prognoses.
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http://dx.doi.org/10.1038/s41598-020-60399-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7044197PMC
February 2020

Cell-based immunofluorescence assay for screening the neurogenesis potential of new drugs in adult hippocampal neural progenitor cells.

Acta Neurobiol Exp (Wars) 2019 ;79(3):302-308

Department of Neurology, The Second Hospital of Hebei Medical University, Hebei, China,

Preclinical studies have suggested that increased adult neurogenesis in the hippocampus might have potential therapeutic effects for Alzheimer's disease and depression; therefore, it is a target for the treatment of some brain diseases. In this technical communication, we propose a cell-based fluorescence assay to study the neurogenesis of adult hippocampal progenitor cells that can be used for high-throughput screening of drugs promoting neurogenesis. Three fluorescent dyes (DAPI, Alexa Fluor 488, and Alexa Fluor 594) and a fluorescence spectrophotometry reader were used, which confirmed that the mutual interference of the three fluorescent dyes is very low. We used this cell-based fluorescence assay to evaluate the effects of three neurotrophic factors, ciliary neurotrophic factor (CNTF), insulin-like growth factor 1 (IGF-1), and IGF-2 on the promotion of neurogenesis in adult hippocampal neural progenitor cells. The fluorescence intensity ratio of the neuronal marker, class III β-tubulin, to the housekeeping protein, glyceraldehyde 3-phosphate dehydrogenase, or nuclear staining dye, DAPI, in CNTF-treated cells was significantly higher than in control cells. The ratios in IGF-1 and IGF-2-treated cells were slightly higher under higher cell density conditions. These results are consistent with those in previous reports; therefore, this report proved the efficacy of this method. Taken together, the results showed that this simple, rapid, and economical cell-based immunofluorescence assay could be a powerful tool for the rapid screening of drugs that promote adult neurogenesis.
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February 2020

The crystal structure of the phytopathogenic bacterial sensor PcrK reveals different cytokinin recognition mechanism from the plant sensor AHK4.

J Struct Biol 2019 10 13;208(1):69-76. Epub 2019 Aug 13.

State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, China. Electronic address:

Plant cytokinins (CKs) are essential for many central cellular processes and play important roles in the interaction between bacteria and plants. Perception of CK is executed by the CHASE domain in the histidine kinase sensors of a class of two-component regulatory systems. Despite advances in understanding the structural basis for CK perception by the sensor AHK4 in Arabidopsis, the molecular mechanism of CK binding by other sensors is unclear. Here, we report the crystal structure of the CHASE domain in the histidine kinase PcrK of the bacterial plant pathogen Xanthomonas campestris pathovar campestris, which senses plant CK, determined at 2.55 Å resolution. The structure reveals that the PcrK has an AHK4-like overall topology and assembles into a homodimer. Strikingly, detailed structural analysis unveils two unique features of the PcrK ligand binding pocket: the size of the pocket is restricted for CK binding, and the PcrK applies a positively charged arginine but not a negatively charged aspartate to recognize the ligand. We propose a model to explain how the PcrK accommodates CK-sized compounds through conformational changes, providing a potential mechanistic framework for understanding ligand recognition by the PcrK.
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http://dx.doi.org/10.1016/j.jsb.2019.08.001DOI Listing
October 2019

Electrophysiological Subtypes and Prognostic Factors of Guillain-Barre Syndrome in Northern China.

Front Neurol 2019 2;10:714. Epub 2019 Jul 2.

Department of Neurology, The Second Hospital of Hebei Medical University, Shijiazhuang, China.

To assess the epidemiology of different electrophysiological subtypes of Guillain-Barre syndrome (GBS) and investigate the factors affecting the prognosis of the acute motor axonal neuropathy (AMAN) subtype in northern China. According to the National Institute of Neurological Disorders and Stroke diagnostic criteria for GBS, 104 consecutive GBS patients were recruited from the Department of Neurology of the Second Hospital of Hebei Medical University, China from 2014 to 2018. Based on nerve conduction studies (NCSs), AMAN was the most common subtype in Northern China, accounting for 58 patients (55.8%). AMAN patients had significantly higher prevalence of antecedent diarrhea, longer duration of hospitalization, and slightly slower recovery than those with acute inflammatory demyelinating polyneuropathy (AIDP), but there was no statistical difference in disease severity or short-term prognosis between AMAN and AIDP. Based on multivariate regression analysis, AMAN patients with antecedent diarrhea (OR = 0.16, 95% CI: 0.03-0.756, = 0.021) or conduction blocks (CBs) (OR = 0.033, 95% CI: 0.001-0.787, = 0.035) had dramatically better short-term prognosis. Decreased compound action potential with distal stimulation (dCMAP) amplitude was associated with significant slower speed of recovery(OR = 8.31, 95% CI: 2.55-27.10, = 0.02). AMAN is still the most common subtype of GBS in northern China. A decline in dCMAP amplitude is predictive factor of a slow recovery and poor outcome of GBS. Diarrhea and CBs may be the factors for better short-term prognosis in AMAN patients in Northern China.
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http://dx.doi.org/10.3389/fneur.2019.00714DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6614537PMC
July 2019

Efficacy and mechanism of acupuncture for ischemic poststroke depression: Study protocol for a multicenter single-blinded randomized sham-controlled trial.

Medicine (Baltimore) 2019 Feb;98(7):e14479

First Teaching Hospital of Tianjin University of Traditional Chinese Medicine.

Introduction: Poststroke depression is a serious and common complication of stroke, especially the ischemic poststroke depression. Antidepressants are used in poststroke depression, and acupuncture may be an alternative approach. However, the efficacy and mechanism of acupuncture for poststroke depression has not been confirmed.

Methods/design: This is a multicenter, central-randomized, single-blind, sham-controlled clinical trial. We will allocate 208 subjects aged between 40 and 80 years old, diagnosed with initial poststroke depression (PSD) within 6 months to 2 groups randomly in a ratio of 1:1. Patients in the experimental group will be treated with traditional acupuncture and placebo pills, whereas the others in the control group will be treated with sham-acupoints acupuncture and antidepressant (fluoxetine hydrochloride tablets). All will be given acupuncture and/or medication treatment for 12 weeks, and then received 12-week follow-up. Patients will be evaluated with the 17-item Hamilton Depression Scale and Se1f-rating Depression Scale for depression state, National Institute of Health Stroke Scale for neurological deficit, Modified Barthel Index for activities of daily living, Treatment Emergent Symptom Scale for side effects of treatments, diagnosis and evaluation criteria of traditional Chinese medicine for stroke (try out) for curative effects of stroke, and clinical global impression for synthesize effect before and the 2nd, 4th, 8th, and 12th week of treatment, 24th week of follow-up. Study on mechanisms of acupuncture will be revealed through the diversity of brain metabolites (choline-containing compounds [Cho], N-acetylaspartate [NAA], myoinositol, glutamine and glutamate complex, creatine [Cr], Cho/Cr, Cho/NAA, Cr/NAA) in bilateral dorsolateral prefrontal cortex and anterior cingulate cortex monitored by proton magnetic resonance spectroscopy, and serum monoamine neurotransmitters (5-hydroxytryptamine, norepinephrine, dopamine) and cytokines (brain-derived neurotrophic factor [BDNF], interleukin [IL]-4, IL-6, IL-10, IL-18, IL-1β, tumor necrosis factor alpha) before and the 12th week of treatment. Baseline characteristics of patients will be summarized by groups and compared with chi-square for categorical variables, and 2-sample t tests or Wilcoxon rank-sum test for the continuous variables. Primary and secondary outcomes according to the measurement times are applicable to univariate repetitive measurement deviation analysis or 2-sample t tests, or Wilcoxon rank-sum test.

Conclusion: The present research is designed to investigate efficacy and mechanism of traditional acupuncture therapy on ischemic PSD, also to explore the correlation between cerebra metabolic and serologic factors, and ischemic PSD. With this research, we are looking forward to find out an appropriate alternative nondrug therapy for PSD people to alleviate the adverse effects and drug dependence caused by antidepressants.
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http://dx.doi.org/10.1097/MD.0000000000014479DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6408034PMC
February 2019

Bioinformatic and Functional Analysis of a Key Determinant Underlying the Substrate Selectivity of the Al Transporter, Nrat1.

Front Plant Sci 2018 7;9:606. Epub 2018 May 7.

State Key Laboratory of Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning, China.

Nrat1 is a member of the natural resistance-associated macrophage protein (Nramp) family of metal ion transporters in all organisms. Different from other Nramp members capable of transporting divalent metals, Nrat1 specifically transports trivalent aluminum (Al) ion. However, molecular mechanism underlying the Al transport selectivity of Nrat1 remains unknown. Here, we performed structure-function analyses of Nrat1 and other Nramp members to gain insights into the determinants of ion selectivity. A phylogenetic analysis showed that plant Nramp transporters could be divided into five groups. OsNrat1 was found in one of the individual clades and clustered with SbNrat1 and ZmNrat1 on the evolutionary tree. Structural modeling revealed that Nrat1 transporters adopted a common LeuT fold shared by many Nramp-family transporters that likely employed an identical transport mechanism. Sequence alignment and evolutionary conservation analysis of amino acids identified a metal-permeation pathway of Nrat1 centered at the metal binding site. The metal binding site of Nrat1 was characterized by two conserved sequence motifs, i.e., the Asp-Pro-Ser-Asn motif (motif A) and the Ala-Ile-Ile-Thr motif (motif B). Replacement of the Ala-Met-Val-Met motif B of the OsNramp3 manganese (Mn) transporter to that of Nrat1 resulted in a partial gain of Al transport activity and a total loss of Mn in yeast. Conversely, substitution of the motif B of OsNrat1 with that of OsNramp3 altered the Al transport activity. These observations indicated the metal binding site, particularly the motif B, as a key determinant of Al selectivity of Nrat1.
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http://dx.doi.org/10.3389/fpls.2018.00606DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5949535PMC
May 2018

[Responsiveness of Chinese version of Neck Outcome Score in subjects with neck pain].

Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi 2018 05;32(5):554-557

Department of Orthopedics, West China Hospital, Sichuan University, Chengdu Sichuan, 610041, P.R.China.

Objective: To analyze responsiveness of Chinese version of Neck Outcome Score (NOOS-C) and provide a reliable measure to assess intervention effect for patients with neck pain.

Methods: Cross-cultural adaptation of NOOS was performed according to the Beaton's guidelines for cross-cultural adaptation of self-report measures. Eighty patients with neck pain were recruited between September 2016 and May 2017. Those patients were assessed using NOOS-C and Chinese version of Neck Disability Index (NDI) before and after intervention. And 71 patients completed those questionnaires. The statistic differences of the score of each subscale and the total scale before and after intervention were evaluated by paired-samples test. Internal responsiveness was determined by effect size (ES) and standardized response mean (SRM) based on the calculated difference before and after intervention. External responsiveness was analyzed by Spearman correlation coefficient.

Results: The differences in symptom subscale, sleep disturbance subscale, participating in everyday life subscale, every day activity and pain subscale, and the scale between before and after intervention were significant ( <0.05) except for mobility subscale ( >0.05). The difference of NDI-C before and after intervention was -12.11%±17.45%, ES was 0.77, and SRM was 0.69. The difference of NOOS-C before and after intervention was 13.74±17.22, ES was 0.83, and SRM was 0.80. Spearman correlation analysis revealed that the relativity about NOOS-C and NDI-C before and after intervention were both negative ( =-0.914, =0.000; =-0.872, =0.000).

Conclusion: NOOS-C's responsiveness is good.
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http://dx.doi.org/10.7507/1002-1892.201801021DOI Listing
May 2018

[Application progress of surface electromyography and surface electromygraphic biofeedback in low back pain].

Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi 2017 04;31(4):504-507

Department of Orthopaedics, West China Hospital, Sichuan University, Chengdu Sichuan, 610041,

Objective: To summarize the application progress of surface electromyography (sEMG) and surface electromygraphic biofeedback (sEMGBF) in low back pain (LBP).

Methods: The related literature about the application of sEMG and sEMGBF in diagnosis and therapy of LBP was summarized and analyzed.

Results: As a auxiliary diagnostic technique, lumbar muscle fatigue, lumbar muscle activity disorder, flexion-relaxation phenomenon, and asymmetry of the paravertebral muscle electromygraphic activity were found in patients with LBP by sEMG. For treatment, sEMG combined with sEMGBF technology to form sEMGBF training. sEMGBF training include sEMGBF training and sEMGBF stretching exercise. sEMGBF training can improve lumbar muscle activity disorder, recover muscle function, and relieve back pain.

Conclusion: sEMG can monitor the electromyographic signal and sEMGBF biofeedback information can relax or strengthen the muscle. It is very meaningful for diagnosis and therapy of LBP.
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http://dx.doi.org/10.7507/1002-1892.201609078DOI Listing
April 2017

Hydride ion (H) transport behavior in barium hydride under high pressure.

Phys Chem Chem Phys 2018 Mar;20(13):8917-8923

State Key Laboratory of Superhard Materials and Institute of Atomic and Molecular Physics, Jilin University, Changchun 130012, China.

Hydride ions (H-) have an appropriate size for fast transport, which makes the conduction of H- attractive. In this work, the H- transport properties of BaH2 have been investigated under pressure using in situ impedance spectroscopy measurements up to 11.2 GPa and density functional theoretical calculations. The H- transport properties, including ionic migration resistance, relaxation frequency, and relative permittivity, change significantly with pressure around 2.3 GPa, which can be attributed to the structural phase transition of BaH2. The ionic migration barrier energy of the P63/mmc phase decreases with pressure, which is responsible for the increased ionic conductivity. A huge dielectric constant at low frequencies is observed, which is related to the polarization of the H- dipoles. The current study establishes general guidelines for developing high-energy storage and conversion devices based on hydride ion transportation.
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http://dx.doi.org/10.1039/C7CP08386FDOI Listing
March 2018

Structure and Electronic Properties of Neutral and Negatively Charged RhB Clusters (n = 3-10): A Density Functional Theory Study.

J Phys Chem A 2017 Aug 18;121(34):6510-6516. Epub 2017 Aug 18.

Department of Physics, Florida A&M University , Tallahassee, Florida 32307, United States.

The geometrical structure and electronic properties of the neutral RhB and singly negatively charged RhB clusters are obtained in the range of 3 ≤ n ≤ 10 using the unbiased CALYPSO structure search method and density functional theory (DFT). A combination of the PBE0 functional and the def2-TZVP basis set is used for determining global minima on potential energy surfaces of the Rh-doped B clusters. The photoelectron spectra of the anions are simulated using the time-dependent density functional theory (TD-DFT) method. Good agreement between our simulated and experimentally obtained photoelectron spectra for RhB provides support to the validity of our theoretical method. The relative stabilities of the ground-state RhB and RhB clusters are estimated using the calculated binding energies, second-order total energy differences, and HOMO-LUMO gaps. It is found that RhB and RhB are the most stable species in the neutral and anionic series, respectively. The chemical bonding analysis reveals that the RhBcluster possesses two sets of delocalized σ and π bonds. In both cases, the Hückel 4N + 2 rule is fulfilled and this cluster possesses both σ and π aromaticities.
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http://dx.doi.org/10.1021/acs.jpca.7b06123DOI Listing
August 2017

New insight into the structural evolution of PbTiO: an unbiased structure search.

Phys Chem Chem Phys 2017 Jan;19(2):1420-1424

College of Physics and Electronic Information, Inner Mongolia University for the Nationalities, Tongliao 028043, China.

Understanding the structural evolution of materials is a challenging problem of condensed matter physics. Solving this problem would open new ways for understanding the behaviors of materials. In this context, we here report unbiased structure searches for a prototypical perovskite oxide, PbTiO, based on the CALYPSO (Crystal structure AnaLYsis by Particle Swarm Optimization) method in conjunction with first-principles calculations. For the first time, we decipher the structure evolution of PbTiO from a zero dimensional (0D) cluster to a two dimensional (2D) layered structure and in the end to a three dimensional (3D) bulk solid. Our unbiased structure search is successful in reproducing the cubic Pm3[combining macron]m and tetragonal P4mm phases of PbTiO at ambient pressure. We also predict a new quasi-planar kite shape structure of the PbTiO cluster, with C symmetry and a surprisingly large HOMO-LUMO gap. Furthermore, by using this method, we predict that the 2D planar PbTiO monolayer is unstable in the perpendicular direction and the 2D PbTiO double layer is dynamically stable, with a hope that it can provide guidance to future synthesis of low dimensional perovskite oxides.
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http://dx.doi.org/10.1039/c6cp07624fDOI Listing
January 2017

Prediction of Stable Ruthenium Silicides from First-Principles Calculations: Stoichiometries, Crystal Structures, and Physical Properties.

ACS Appl Mater Interfaces 2015 Dec 25;7(48):26776-82. Epub 2015 Nov 25.

Centre for Science at Extreme Conditions and SUPA, School of Physics and Astronomy, The University of Edinburgh , Edinburgh EH9 3JZ, United Kingdom.

We present results of an unbiased structure search for stable ruthenium silicide compounds with various stoichiometries, using a recently developed technique that combines particle swarm optimization algorithms with first-principles calculations. Two experimentally observed structures of ruthenium silicides, RuSi (space group P2(1)3) and Ru2Si3 (space group Pbcn), are successfully reproduced under ambient pressure conditions. In addition, a stable RuSi2 compound with β-FeSi2 structure type (space group Cmca) was found. The calculations of the formation enthalpy, elastic constants, and phonon dispersions demonstrate the Cmca-RuSi2 compound is energetically, mechanically, and dynamically stable. The analysis of electronic band structures and densities of state reveals that the Cmca-RuSi2 phase is a semiconductor with a direct band gap of 0.480 eV and is stabilized by strong covalent bonding between Ru and neighboring Si atoms. On the basis of the Mulliken overlap population analysis, the Vickers hardness of the Cmca structure RuSi2 is estimated to be 28.0 GPa, indicating its ultra-incompressible nature.
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http://dx.doi.org/10.1021/acsami.5b08807DOI Listing
December 2015

[The effect of the acupuncture intervention of dredging Governor Vessel and regulating mentality for the medication treatment of post-stroke depression].

Zhongguo Zhen Jiu 2015 Aug;35(8):753-7

Objective: To observe the differences in onset time and the overall efficacy of the acupuncture therapy of dredging Governor Vessel and regulating mentality combined with fluoxetine and the fluoxetine for post-stroke depression(PSD).

Methods: Sixty-three patients were randomly divided into an acupuncture intervention of dredging Governor Vessel and regulating mentality group(acupuncture and medication group, 33 cases) and a control group (medication group, 30 cases). In the medication group, 20 mg fluoxetine was used by oral administration, once a day at 7:00 in the morning, continuously for 4 weeks. In the acupuncture and medication group, based on the oral administration of fluoxetine, the acupuncture intervention of dredging Governor Vessel and regulating mentality was applied mainly at Baihui(GV 20), Fengfu(GV 16), Shenting(GV 24), Shuigou(GV 26), Dazhui(GV 14) and Shendao(GV 11), once a day, 6 times a week, continuously for 4 weeks. Twenty-four items in Hamilton Depression Scale(HAMD), modified Edinburgh Scandinavia Stroke Scale(MESSS) and activity of daily life scale(ADL, Barthel index, BI) were used before and after 2-week and 4-week treatment. The efficacy was compared between the two groups.

Results: After 2-week treatment, the HAMD score and the MESSS score in the acupuncture and medication group were obviously decreased and the BI score was apparently increased(all P<0. 01). In the medication group, however, the score of every scale was not statistically different from that before treatment(P'>0. 05). After 4-week treatment, HAMD scores and MESSS scores in the two groups were obviously decreased and the BI scores I were apparently increased(all P<0. 01). After 2-week and 4-week treatment, the HAMD scores and the MESSS scores in the acupuncture and medication group were lower than those in the medication group and the BI scores were higher than those in the medication group(P<0. 01, P<0. 05). The total effective rate of anti-depression (97. 0%, 32/33) the total effective rate of nerve function impairment(90. 9%, 30/33) and the total effective rate of daily life activity(97. 0% 32/33) in the acupuncture and medication group were better than 80. 0% (24/30), 80. 0%(24/30), 83. 3%(25/30) in the medication group(all P<0. 05).

Conclusion: The acupuncture therapy of dredging Governor Vessel and regulating mentality could reduce the onset time of anti-depression medicine treatment of PSD and enhance the overall efficacy. Therefore, it enhances the clinical compliance.
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August 2015

Carbon coated face-centered cubic Ru-C nanoalloys.

Nanoscale 2014 Sep;6(17):10370-6

State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, Hebei 066004, China.

Carbon-encapsulated ruthenium-carbon (Ru-C) nanoalloys were synthesized by dynamic shocks. The Ru-C alloy shows a new fcc structure different from the original hcp structure of metal Ru. This fcc phase is assigned to a Ru32C4 solid solution with a lattice parameter of 3.868(2) Å and a bulk modulus KT0 of 272(12) GPa. The small amount of carbon in the solid solution enhances the thermodynamic and chemical stabilities with respect to pure Ru, as well as induces changes in the electronic properties, which have direct applications in improving the material's catalytic activity and selectivity.
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http://dx.doi.org/10.1039/c4nr02632bDOI Listing
September 2014

Modulated structure and molecular dissociation of solid chlorine at high pressures.

J Chem Phys 2012 Aug;137(6):064502

State Key Lab of Superhard Materials, Jilin University, Changchun 130012, People's Republic of China.

Among diatomic molecular halogen solids, high pressure structures of solid chlorine (Cl(2)) remain elusive and least studied. We here report first-principles structural search on solid Cl(2) at high pressures through our developed particle-swarm optimization algorithm. We successfully reproduced the known molecular Cmca phase (phase I) at low pressure and found that it remains stable up to a high pressure 142 GPa. At 150 GPa, our structural searches identified several energetically competitive, structurally similar, and modulated structures. Analysis of the structural results and their similarity with those in solid Br(2) and I(2), it was suggested that solid Cl(2) adopts an incommensurate modulated structure with a modulation wave close to 2∕7 in a narrow pressure range 142-157 GPa. Eventually, our simulations at >157 GPa were able to predict the molecular dissociation of solid Cl(2) into monatomic phases having body centered orthorhombic (bco) and face-centered cubic (fcc) structures, respectively. One unique monatomic structural feature of solid Cl(2) is the absence of intermediate body centered tetragonal (bct) structure during the bco → fcc transition, which however has been observed or theoretically predicted in solid Br(2) and I(2). Electron-phonon coupling calculations revealed that solid Cl(2) becomes superconductors within bco and fcc phases possessing a highest superconducting temperature of 13.03 K at 380 GPa. We further probed the molecular Cmca → incommensurate phase transition mechanism and found that the softening of the A(g) vibrational (rotational) Raman mode in the Cmca phase might be the driving force to initiate the transition.
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http://dx.doi.org/10.1063/1.4742152DOI Listing
August 2012

Dissociation of methane under high pressure.

J Chem Phys 2010 Oct;133(14):144508

State Key Lab of Superhard Materials, Jilin University, Changchun 130012, People's Republic of China.

Methane is an extremely important energy source with a great abundance in nature and plays a significant role in planetary physics, being one of the major constituents of giant planets Uranus and Neptune. The stable crystal forms of methane under extreme conditions are of great fundamental interest. Using the ab initio evolutionary algorithm for crystal structure prediction, we found three novel insulating molecular structures with P2(1)2(1)2(1), Pnma, and Cmcm space groups. Remarkably, under high pressure, methane becomes unstable and dissociates into ethane (C(2)H(6)) at 95 GPa, butane (C(4)H(10)) at 158 GPa, and further, carbon (diamond) and hydrogen above 287 GPa at zero temperature. We have computed the pressure-temperature phase diagram, which sheds light into the seemingly conflicting observations of the unusually low formation pressure of diamond at high temperature and the failure of experimental observation of dissociation at room temperature. Our results support the idea of diamond formation in the interiors of giant planets such as Neptune.
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http://dx.doi.org/10.1063/1.3488102DOI Listing
October 2010

High-pressure crystal structures and superconductivity of Stannane (SnH4).

Proc Natl Acad Sci U S A 2010 Jan 6;107(4):1317-20. Epub 2010 Jan 6.

National Laboratory of Superhard Materials, Jilin University, Changchun 130012, PR China.

There is great interest in the exploration of hydrogen-rich compounds upon strong compression where they can become superconductors. Stannane (SnH(4)) has been proposed to be a potential high-temperature superconductor under pressure, but its high-pressure crystal structures, fundamental for the understanding of superconductivity, remain unsolved. Using an ab initio evolutionary algorithm for crystal structure prediction, we propose the existence of two unique high-pressure metallic phases having space groups Ama2 and P6(3)/mmc, which both contain hexagonal layers of Sn atoms and semimolecular (perhydride) H(2) units. Enthalpy calculations reveal that the Ama2 and P6(3)/mmc structures are stable at 96-180 GPa and above 180 GPa, respectively, while below 96 GPa SnH(4) is unstable with respect to elemental decomposition. The application of the Allen-Dynes modified McMillan equation reveals high superconducting temperatures of 15-22 K for the Ama2 phase at 120 GPa and 52-62 K for the P6(3)/mmc phase at 200 GPa.
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http://dx.doi.org/10.1073/pnas.0908342107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2824346PMC
January 2010
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