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1.
Physiother Theory Pract ; : 1-10, 2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31686567

RESUMO

Objectives: To describe change in trunk flexor endurance and intra-abdominal pressure (IAP) associated with trunk flexor assessment and explore factors associated with change in trunk flexor endurance during the first postpartum year.Design: Ancillary analysis of an ongoing prospective cohort study.Methods: Participants (N = 282) were primiparous women delivered vaginally. They completed trunk flexor endurance testing while assessing IAP, body habitus measures (body mass index, waist circumference, and body composition), and questionnaires 5-10 weeks and 11-15 months postpartum. We investigated change in trunk flexor endurance by quartile of improvement and factors associated with improvement (Q4 vs. Q1-Q3) using multivariable models, adjusted for baseline endurance.Results: Mean age was 28 ± 5 years. The median (IQR) trunk flexor hold time increased from early to late postpartum (129/IQR = 68, 217 vs 148/IQR = 80, 265 seconds, p = .01) and mean (SD) IAP decreased (55/SD = 13 vs 48/SD = 14 cmH20, p < .0001). The most improved group (Q4) increased endurance time by 176 seconds (95% CI = 103, 254), were less likely to be Hispanic, more likely to be older, more educated, and have lower measures of body habitus than women in Q1-Q3. Conclusion: Trunk flexor endurance increased and IAP decreased over one year postpartum. Lower body habitus and higher age early postpartum predicted greatest improvement in trunk flexor endurance at 1 year.

2.
BMC Infect Dis ; 19(1): 962, 2019 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-31711435

RESUMO

BACKGROUND: High-risk human papillomavirus (HR-HPV) testing is more sensitive than cytology for the detection of cervical cancer and its precursors. However, limited and inconsistent data are available about the efficacy of the combination of these two methods for screening cervical adenocarcinoma. This multicenter retrospective study investigated the screening results of a cohort of Chinese patients who were subsequently diagnosed with invasive cervical adenocarcinoma, with the goal of identifying the optimal cervical adenocarcinoma screening method. METHODS: We retrospectively retrieved and analyzed the data from patients with histologically confirmed primary invasive cervical adenocarcinoma from eight local pathology laboratories operated by KingMed Diagnostics, the largest independent operator of pathology laboratories in China, over a 2-year period. Only patients who underwent cytology and/or HR-HPV testing within 6 months before the adenocarcinoma diagnosis were included. HR-HPV DNA was detected using one of two HPV test kits: the Hybrid Capture 2 (HC2) assay (Qiagen, Hilden, Germany) and an HPV genotyping panel (Yaneng Bio, Shenzhen, China). RESULTS: Of the 311 patients, 136 underwent cytology alone, 106 underwent HR-HPV testing alone, and 69 underwent cytology and HR-HPV co-testing. The sensitivities of cytology alone (64.0, 95% confidence interval [CI]: 55.9-72.0) and HR-HPV testing alone (66.0, 95% CI: 57.0-75.1) were similar (P = 0.738). The sensitivity of cytology and HR-HPV co-testing (87.0, 95% CI: 79.0-94.9) was significantly higher than that of either cytology (P = 0.001) or HR-HPV testing alone (P = 0.002). CONCLUSIONS: Both cytology alone and HR-HPV testing alone showed poor screening efficiency, whereas the combination of the two clearly increased the efficiency of primary cervical adenocarcinoma screening. Thus, cytology and HR-HPV co-testing might be the most efficient cervical adenocarcinoma screening method.

4.
Sci Rep ; 9(1): 16522, 2019 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-31712736

RESUMO

Circular RNAs (circRNAs) play important roles in animals, plants, and fungi. However, no circRNAs have been reported in Ganoderma lucidum. Here, we carried out a genome-wide identification of the circRNAs in G.lucidum using RNA-Seq data, and analyzed their features. In total, 250 and 2193 circRNAs were identified from strand-specific RNA-seq data generated from the polyA(-) and polyA(-)/RNase R-treated libraries, respectively. Six of 131 (4.58%) predicted circRNAs were experimentally confirmed. Across three developmental stages, 731 exonic circRNAs (back spliced read counts ≥ 5) and their parent genes were further analyzed. CircRNAs were preferred originating from exons with flanking introns, and the lengths of the flanking intron were longer than those of the control introns. A total of 200 circRNAs were differentially expressed across the three developmental stages of G. lucidum. The expression profiles of 119 (16.3%) exonic circRNAs and their parent genes showed significant positive correlations (r ≥ 0.9, q < 0.01), whereas 226 (30.9%) exonic circRNAs and their parent genes exhibited significant negative correlations (r ≤ -0.9, q < 0.01), in which 53 parent genes are potentially involved in the transcriptional regulation, polysaccharide biosynthesis etc. Our results indicated that circRNAs are present in G. lucidum, with potentially important regulatory roles.

5.
Theor Appl Genet ; 2019 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-31745579

RESUMO

KEY MESSAGE: The resistance gene Gm6 was mapped and characterized using near-isogenic and pyramided lines, followed by marker-assisted selection to develop lines with resistance to both gall midge and brown planthopper. The Asian rice gall midge (GM; Orseolia oryzae; Diptera: Cecidomyiidae) is a major destructive pest affecting rice cultivation regions. The characterization of GM-resistance genes and the breeding of resistant varieties are together considered the most efficient strategy for managing this insect. Here, the Gm6 resistance gene derived from the Kangwenqingzhan (KW) variety was found to be located on the long arm of chromosome 4 using the F2 population of 9311/KW. The region was narrowed to a 90-kb segment flanked by the markers YW91 and YW3-4 using backcrossing populations. Based on no-choice feeding and host choice tests, GM development and growth in near-isogenic lines (NILs) were severely restricted compared to that in the 9311 control. On day 8, the average GM body length was 0.69 mm and 0.56 mm on NILs and 9311, respectively, and the differences were more significant at later time points. However, GM insects exhibited no host preference between NILs and 9311, and there was normal egg hatching on the resistant plants. We developed pyramided lines carrying BPH27, BPH36, and Gm6 by crossing and backcrossing with marker-assisted selection. These lines were similar to the KW parent in terms of agronomic traits while also exhibiting high resistance to brown planthopper (BPH) and GM. The present mapping and characterization of Gm6 will facilitate map-based cloning of this important resistance gene and its application in the breeding of insect-resistant rice varieties.

6.
Dalton Trans ; 2019 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-31750467

RESUMO

Two new organic-inorganic hybrid metal halides, formulated as (C7H13N2)2MnCl4 (1) and (C6H11N2)PbBr3 (2), were prepared by a two-component ionothermal approach using multifunctional ionic liquids as solvents, charge-balancing agents, and halide sources. Compound 1 has an ionic zero-dimensional structure showing bright green luminescence with a high quantum yield of up to 70.78%. Compound 2 has a chain-like structure with a large second harmonic generation efficiency which is approximately 8× that of KH2PO4.

7.
Taiwan J Obstet Gynecol ; 58(6): 808-813, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31759533

RESUMO

OBJECTIVE: The aim was to determine the role of visfatin (VF) and human fetuin A (AHSG) in the development of gestational diabetes mellitus (GDM) and to explore the association between these variables and adverse outcomes. MATERIALS AND METHODS: We carried out our study on 68 cases of GDM pregnant women and 42 cases of healthy pregnant women, including 56 cases with diet control and 12 cases with insulin treatment. Enzyme-linked immunoassay (ELISA) was used to test the expression levels of VF and AHSG in maternal and umbilical cord serum. Immunohistochemistry (ICH) was used to test the expression level of the VF protein in placental tissue. RESULTS: The expression levels of VF and AHSG in maternal and umbilical cord serum and the expression level of VF in placental tissue in GDM pregnant women were higher than those in healthy pregnant women. The incidence of adverse outcomes in the GDM pregnant women was higher than that in healthy pregnant women, and these differences were statistically significant (P < 0.05). Those who had higher expression levels of VF or AHSG had a higher incidence of adverse outcomes (P < 0.05). CONCLUSION: The expression of VF and AHSG may participate in the development of GDM. A test of VF and AHSG in GDM pregnant women may have some predictive value for the occurrence of adverse outcomes.

8.
ACS Appl Mater Interfaces ; 11(47): 44144-44152, 2019 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-31687798

RESUMO

Cation-disordered Li-excess lithium-transition metal (Li-TM) oxides designed based on the percolation theory are regarded as a promising new type of high-performance cathode material for Li-ion batteries. Herein, cation-disordered rocksalt-type Li-Fe-Ti oxides of Li0.89Fe0.44Ti0.45O2, Li1.18Fe0.34Ti0.45O2, and Li1.24Fe0.38Ti0.38O2 with different Li-to-transition metal ratios (Li/TM = 1, 1.49, or 1.63) are investigated to understand the effect of a Li excess on the electrochemical Li-ion storage properties. The Li excess leads to local structural fluctuations of the as-prepared Li-Fe-Ti oxides, contributing to the formation of 0-TM diffusion channels for rapid Li-ion migration. The as-prepared Li-excess Li-Fe-Ti oxide cathodes (Li/TM = 1.49 and Li/TM = 1.63) deliver a higher reversible capacity of over 220 mAh g-1 and a better rate capability compared to the Li/TM = 1 electrode, which possesses a maximum discharge capacity of only about 165 mAh g-1. The redox reactions of Fe2+/Fe3+ and O2-/O22- achieve the main capacity of the Li-excess Li-Fe-Ti oxide cathodes during cycling, as supported by 57Fe Mössbauer spectroscopy, O 1s X-ray photoelectron spectroscopy, and O K-edge soft X-ray absorption spectroscopy.

9.
Plant Sci ; 289: 110282, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31623771

RESUMO

The metabolic profile of rice (Oryza sativa) during germination under low temperature (LT) has not been reported. In this study, the rice varieties 02428 (japonica) and YZX (indica) were subjected to experiments consisting of treatments including LT, normal temperature (NT) and a transition from LT to NT, and tissues were sampled at different time points during germination. A total of 730 metabolites were detected by a liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based widely targeted metabolomics method. On the basis of the screening criteria of increased contents under LT and decreased contents under NT, we identified 35 different metabolites that responded to LT stress among the 730 metabolites. Furthermore, the content differences of the 35 metabolites were compared when the samples were transferred from LT to NT. According to a fold change <0.5 or a variable importance in projection (VIP) score>1 at the transition point, 7 out of the 35 metabolites responded significantly to LT stress and were defined as key metabolites. A partial least squares (PLS) regression model of seven key metabolites with seedling length (SL), seedling area (SSA), and seedling volume (SV) was constructed, and the fitting effect was good. These seven key metabolites participate in the biosynthesis of amino acids and phenylpropanoids and in the metabolism of glutathione and inositol phosphate. This study laid a foundation for an improved understanding of the LT-germination mechanism of rice seeds.

10.
Science ; 366(6461): 132-135, 2019 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-31604316

RESUMO

Quantum mechanics and the general theory of relativity are two pillars of modern physics. However, a coherent unified framework of the two theories remains an open problem. Attempts to quantize general relativity have led to many rival models of quantum gravity, which, however, generally lack experimental foundations. We report a quantum optical experimental test of event formalism of quantum fields, a theory that attempts to present a coherent description of quantum fields in exotic spacetimes containing closed timelike curves and ordinary spacetime. We experimentally test a prediction of the theory with the quantum satellite Micius that a pair of time-energy-entangled particles probabilistically decorrelate passing through different regions of the gravitational potential of Earth. Our measurement results are consistent with the standard quantum theory and hence do not support the prediction of event formalism.

11.
Biochemistry ; 58(41): 4224-4235, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31568719

RESUMO

Cholesterol catabolism plays an important role in Mycobacterium tuberculosis's (Mtb's) survival and persistence in the host. Mtb exploits three ß-oxidation cycles to fully degrade the side chain of cholesterol. Five cistronic genes in a single operon encode three enzymes, 3-oxo-4-pregnene-20-carboxyl-CoA dehydrogenase (ChsE1-ChsE2), 3-oxo-4,17-pregnadiene-20-carboxyl-CoA hydratase (ChsH1-ChsH2), and 17-hydroxy-3-oxo-4-pregnene-20-carboxyl-CoA retro-aldolase (Ltp2), to perform the last ß-oxidation cycle in this pathway. Among these three enzymes, ChsH1-ChsH2 and Ltp2 form a protein complex that is required for the catalysis of carbon-carbon bond cleavage. In this work, we report the structure of the full length ChsH1-ChsH2-Ltp2 complex based on small-angle X-ray scattering and single-particle electron microscopy data. Mutagenesis experiments confirm the requirement for Ltp2 to catalyze the retro-aldol reaction. The structure illustrates how acyl transfer between enzymes may occur. Each protomer of the ChsH1-ChsH2-Ltp2 complex contains three protein components: a chain of ChsH1, a chain of ChsH2, and a chain of Ltp2. Two protomers dimerize at the interface of Ltp2 to form a heterohexameric structure. This unique heterohexameric structure of the ChsH1-ChsH2-Ltp2 complex provides entry to further understand the mechanism of cholesterol catabolism in Mtb.

12.
J Hazard Mater ; : 121386, 2019 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-31635822

RESUMO

Adsorption is widely used in removal of toxic vanadium (V) [V(V)] from water streams, and a fit-for-purpose adsorbent plays a vital role in this process. Herein HZrO@D201, an adsorbent with decoration of nanosized hydrous zirconium oxide (HZrO) on anion exchange resin D201, is fabricated for efficient V(V) removal. Compared to pristine D201, HZrO@D201 excelled in V(V) removal with a maximum adsorption capacity of 118.1 mg/g, due to potential formation of inner sphere complexation between V(V) and HZrO. HZrO@D201 could also functioned well in a wide pH range (3.00 to 9.00) and exhibited outstanding selective V(V) adsorption under the presence of competing anions (chloride, nitrate, sulfate, and phosphate). The adsorption thermodynamics was in accordance with the Langmuir model, while adsorption kinetics followed the Pseudo-Second-Order model. When treating actual vanadium contaminated groundwater from Panzhihua region (China), HZrO@D201 indicated a satisfactory lifespan in the column experiment for V(V) removal (2.41 times longer than D201), and the treated groundwater could meet the vanadium standard of drinking water source in China (less than 50 µg/L). Regeneration of HZrO@D201 was easily achievable with negligible capacity loss. Results from this work suggests a promising application potential of HZrO@D201 in vanadium pollution control.

13.
Zhongguo Zhong Yao Za Zhi ; 44(16): 3558-3561, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31602922

RESUMO

To preliminarily investigate the effect of Tripterygium Glycosides Tablets( TGT) combined with traditional Chinese medicine( TCM) on the fertility and female menstruation on persons who have took during childhood. The children with henoch-schonlein purpura( HSP) or henoch-schonlein purpura nephritis( HSPN) who treated with TGT under 18 years old and now older than 18 years old( including 18 years old) during January 1998 to December 2010 were selected in our research. The content of follow-up visit included marriage,marriage age,fertility and child health; and unmarried female patients were asked whether they had menstrual abnormalities. The data of the unmarried female patients,including age,clinical classification,TCM syndrome type,initial dose and other related factors that may affect menstrual cycle,was analyzed by using binary logistic regression analysis. A total of 195 patients who met the criteria were followed up in this study,and 26 patients married for more than 1 year. Among the 26 married patients,1 HSP patient had no birth planning due to rheumatoid arthritis,and the remaining 25 patients all had given birth or were pregnant. The 169 unmarried patients included 89 female patients. Among the 89 female patients,4 cases refused to tell the menstrual situations,72 cases had normal menstruation( 84. 7%),13 cases had abnormal menstruation( 15. 3%),and there was no case of amenorrhea. Logistic regression analysis results showed that the age,clinical classification,TCM syndrome type and initial dose had no correlation with abnormal menstruation. Our results demonstrated that TGT has no effect on adulthood fertility among patients who took TGT combined with traditional Chinese medicine during childhood.


Assuntos
Medicamentos de Ervas Chinesas/farmacologia , Fertilidade/efeitos dos fármacos , Glicosídeos/farmacologia , Púrpura de Schoenlein-Henoch/tratamento farmacológico , Tripterygium/química , Adolescente , Adulto , Criança , Feminino , Humanos , Medicina Tradicional Chinesa , Comprimidos
14.
Nat Commun ; 10(1): 4765, 2019 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-31628366

RESUMO

Spin-orbit coupling (SOC) has gained much attention for its rich physical phenomena and highly promising applications in spintronic devices. The Rashba-type SOC in systems with inversion symmetry breaking is particularly attractive for spintronics applications since it allows for flexible manipulation of spin current by external electric fields. Here, we report the discovery of a giant anisotropic Rashba-like spin splitting along three momentum directions (3D Rashba-like spin splitting) with a helical spin polarization around the M points in the Brillouin zone of trigonal layered PtBi2. Due to its inversion asymmetry and reduced symmetry at the M point, Rashba-type as well as Dresselhaus-type SOC cooperatively yield a 3D spin splitting with αR ≈ 4.36 eV Å in PtBi2. The experimental realization of 3D Rashba-like spin splitting not only has fundamental interests but also paves the way to the future exploration of a new class of material with unprecedented functionalities for spintronics applications.

15.
J Bone Miner Res ; 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31614022

RESUMO

Circulating microRNAs (miRNAs) play important roles in regulating gene expression and have been reported to be involved in various metabolic diseases, including osteoporosis. Although the transcriptional regulation of osteoblast differentiation has been well characterized, the role of circulating miRNAs in this process is poorly understood. Here we discovered that the level of circulating miR-19b was significantly lower in osteoporotic patients with vertebral compression fractures than that of healthy controls. The expression level of miR-19b was increased during osteoblastic differentiation of human mesenchymal stem cells (hMSCs) and MC3T3-E1 cells, and transfection with synthetic miR-19b could promote osteoblastic differentiation of hMSCs and MC3T3-E1 cells. PTEN (phosphatase and tensin homolog deleted from chromosome 10) was found to be directly repressed by miR-19b, with a concomitant increase in Runx2 expression and increased phosphorylation of AKT (protein kinase B, PKB). The expression level of circulating miR-19b in aged ovariectomized mice was significantly lower than in young mice. Moreover, the osteoporotic bone phenotype in aged ovariectomized mice was alleviated by the injection of chemically modified miR-19b (agomiR-19b). Taken together, our results show that circulating miR-19b plays an important role in enhancing osteoblastogenesis, possibly through regulation of the PTEN/pAKT/Runx2 pathway, and may be a useful therapeutic target in bone loss disorders, such as osteoporosis. © 2019 American Society for Bone and Mineral Research.

16.
Oncol Rep ; 42(6): 2426-2434, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31638261

RESUMO

RAD51, is a key homologous recombination protein that repairs DNA damage and maintains gene diversity and stability. Previous studies have demonstrated that the over­expression of RAD51 is associated with chemotherapy resistance of tumor cells to chemotherapy, and enhanced activity of DNA damage repair (DDR) systems contributes to resistance of adult T­cell leukemia­lymphoma (ATL) resistance to chemotherapy. Thus, targeting RAD51 is a potential strategy for the sensitization of ATL cells to chemotherapeutic drugs by inducing DNA damage. In general, cells can repair minor DNA damage through DDR; however, serious DNA damage may cause cell toxicity in cells which cannot be restored. In the present, down regulation of RAD51 by shRNA and imatinib sensitized Jurkat cells to etoposide by decreasing the activity of homologous recombination (HR). We found that the suppression of RAD51 by shRNA inhibited tumor cells proliferation and enhanced apoptosis of Jurkat cells after etoposide treatment. Importantly, downregulation of RAD51 by imatinib obviously increased the apoptosis of Jurkat cell after etoposide treatment. These results demonstrated that RAD51 may be of great value to as a novel target for the clinical treatment of adult T­cell leukemia­lymphoma (ATL), and it may improve the survival of leukemia patients.

17.
PLoS One ; 14(10): e0224096, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31661493

RESUMO

Staphylococcus aureus (S. aureus) infections are a leading cause of death by an infectious agent. Survival within host phagocytic cells is one mechanism by which S. aureus evades antibiotic treatment. A novel THIOMAB™ antibody-antibiotic conjugate (TAC) strategy was developed to kill S. aureus intracellularly and mitigate the spread of infection. In this report, we used a longitudinal whole-body bioluminescence imaging method to study the antibacterial dynamics of TAC alone or in combination with vancomycin in a mouse infection model. Injections of stably luminescent S. aureus bacteria into mice resulted in exponential increases in whole body bioluminescence with a reduction in body weight and survival rate. Vancomycin, a standard-of-care antibiotic, suppressed bacterial growth in mice. However, bacterial growth rebounded in these animals once treatment was discontinued. In contrast, single dose of TAC showed rapid reduction of bioluminescence intensity, which persisted for up to 19 days. The combination of TAC and vancomycin achieved a more sustained and significantly greater reduction of bioluminescence compared with vancomycin alone. In summary, the present study showed an imaging method to longitudinally assess antibacterial drug dynamics in mice and demonstrated that TAC monotherapy or in combination with vancomycin had superior and sustained activity compared to vancomycin alone.

18.
Int J Biometeorol ; 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31654197

RESUMO

Plateau zokor (Myospalax baileyi) and plateau pika (Ochotona curzoniae) are endemic fossorial vertebrates in the Qinghai-Tibetan Plateau alpine meadow ecosystem. Their different burrowing activities together transform soil structure and then significantly change the landscape of meadow ecosystem. However, how their burrowing activities impact greenhouse gas (GHG) emissions and the pattern of GHG emissions between different types of tunnel burrowing still remain obscure. In this study, we conducted in situ measurements quantitatively investigating the impacts of the different burrowing activities of zokors and pikas on three main GHG CO2, CH4, and N2O from an alpine meadow ecosystem in southeastern Qinghai-Tibetan Plateau. Our results showed that zokor hummocks and pika burrows were sources of CO2 and N2O and sinks of CH4. Zokors burrowing increased N2O in the atmosphere, decreased CO2, and enhanced CH4 absorbing, while pikas burrowing increased N2O in the atmosphere and enhanced CH4 absorbing. Considering the controversial role of fossorial vertebrates in Qinghai-Tibetan Plateau, this study also shed lights on effective management of animal activities with the aim of stabilizing or increasing ecosystem carbon sequestration.

19.
Med Hypotheses ; 132: 109233, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31606702

RESUMO

The guidelines for cardiopulmonary resuscitation (CPR) in pediatric advanced life support suggest that midazolam is the preferred agent for sedation in patients with mild hypothermia, whereas children with cardiac arrest (CA) are at a crucial stage regarding their immature nervous system. Studies have shown that midazolam may have a detrimental effect on the developmental of the pediatric nervous system. Our previous study found that midazolam induced neuronal damage after CPR in young rats. It is speculated that: midazolam causes the potential injury of neurons by inhibiting mitochondrial autophagy expression and is an important factor for the poor prognosis in children after successful CPR. This project intends to adopt the modified asphyxiant CPR model in juvenile rats. Survival rate, neurological function and histopathological changes were evaluated to determine the protective effects of appropriate sedation depth on cerebral ischemia-reperfusion injury in juvenile rats after CPR. Combined with cell biology and molecular biology related technologies, the mechanism by which the mitochondrial pinkl-parkin signaling pathway induces autophagy to inhibit neuronal apoptosis may be key factor in the protective effects of sedation depth on the brain. The aim of this study is to provide experimental evidence and elucidate the mechanisms of improvement of cerebral ischemia-reperfusion injury by sedation depth in children after successful CPR and to lay a theoretical and experimental basis for clinical treatment.

20.
Phys Rev Lett ; 123(10): 105701, 2019 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-31573294

RESUMO

Relaxation processes significantly influence the properties of glass materials. However, understanding their specific origins is difficult; even more challenging is to forecast them theoretically. In this study, using microseconds molecular dynamics simulations together with an accurate many-body interaction potential, we predict that an Al_{90}Sm_{10} metallic glass would have complex relaxation behaviors: In addition to the main (α) relaxation, the glass (i) shows a pronounced secondary (ß) relaxation at cryogenic temperatures and (ii) exhibits an anomalous relaxation process (α_{2}) accompanying α relaxation. Both of the predictions are verified by experiments. Computational simulations reveal the microscopic origins of relaxation processes: while the pronounced ß relaxation is attributed to the abundance of stringlike cooperative atomic rearrangements, the anomalous α_{2} process is found to correlate with the decoupling of the faster motions of Al with slower Sm atoms. The combination of simulations and experiments represents a first glimpse of what may become a predictive routine and integral step for glass physics.

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