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1.
Biomater Sci ; 2023 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-36691757

RESUMO

As a kind of basic polypeptide with antibacterial properties, antimicrobial peptides play an important role in resisting the invasion of foreign microorganisms. Antimicrobial peptides have a wide range of antimicrobial activities against bacteria, fungi, viruses and other microorganisms. They are active against traditional antibiotic-resistant strains and do not easily cause bacterial resistance. In this study, we synthesized an antibacterial peptide library by a Fmoc solid phase synthesis method, and screened the peptide chain FWKFK by modified cell membrane chromatography. The minimum inhibitory concentration of FWKFK against E. coli and S. aureus was 200 µg mL-1 and 250 µg mL-1, respectively, and FWKFK also had inhibitory effects on P. aeruginosa, B. subtilis and S. epidermidis. Its biocompatibility and therapeutic effect on mouse wounds were then tested. The results showed that the survival rate of normal cells after FWKFK treatment was more than 95%, the hemolysis rate of red blood cells was as low as 6%, and it had a significant effect on wound healing in mice.

2.
Nat Nanotechnol ; 18(1): 29-35, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36543882

RESUMO

Photoinduced charge transfer in van der Waals heterostructures occurs on the 100 fs timescale despite weak interlayer coupling and momentum mismatch. However, little is understood about the microscopic mechanism behind this ultrafast process and the role of the lattice in mediating it. Here, using femtosecond electron diffraction, we directly visualize lattice dynamics in photoexcited heterostructures of WSe2/WS2 monolayers. Following the selective excitation of WSe2, we measure the concurrent heating of both WSe2 and WS2 on a picosecond timescale-an observation that is not explained by phonon transport across the interface. Using first-principles calculations, we identify a fast channel involving an electronic state hybridized across the heterostructure, enabling phonon-assisted interlayer transfer of photoexcited electrons. Phonons are emitted in both layers on the femtosecond timescale via this channel, consistent with the simultaneous lattice heating observed experimentally. Taken together, our work indicates strong electron-phonon coupling via layer-hybridized electronic states-a novel route to control energy transport across atomic junctions.

3.
J Control Release ; 354: 167-187, 2023 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-36581260

RESUMO

Polysaccharide-based nanocarriers (PBNs) are the focus of extensive investigation because of their biocompatibility, low cost, wide availability, and chemical versatility, which allow a wide range of anticancer agents to be loaded within the nanocarriers. Similar to other nanocarriers, most PBNs are designed to extravasate out of tumor vessels, depending on the enhanced permeability and retention (EPR) effect. However, the EPR effect is compromised in some tumors due to the heterogeneity of tumor structures. Transvascular transport efficacy is decreased by complex blood vessels and condensed tumor stroma. The limited extravasation impedes efficient drug delivery into tumor parenchyma, and thus affects the subsequent tumor accumulation, which hinders the therapeutic effect of PBNs. Therefore, overcoming the biological barriers that restrict extravasation from tumor vessels is of great importance in PBN design. Many strategies have been developed to enhance the EPR effect that involve nanocarrier property regulation and tumor structure remodeling. Moreover, some researchers have proposed active transcytosis pathways that are complementary to the paracellular EPR effect to increase the transvascular extravasation efficiency of PBNs. In this review, we summarize the recent advances in the design of PBNs with enhanced transvascular transport to enable optimization of PBNs in the extravasation of the drug delivery process. We also discuss the obstacles and challenges that need to be addressed to clarify the transendothemial mechanism of PBNs and the potential interactions between extravasation and other drug delivery steps.

4.
Front Vet Sci ; 9: 1033107, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36570511

RESUMO

The family Parvoviridae comprises many major viral pathogens that can infect humans and multiple other species, causing severe diseases. However, knowledge of parvoviruses that infect equids is limited. In the present study, we found that three equine parvoviruses (EqPVs), namely, equine parvovirus-hepatitis (EqPV-H), equine parvovirus-cerebrospinal fluid (EqPV-CSF) and equine copivirus (EqCoPV) cocirculated among horses in China. We examined the prevalence of these three EqPVs in 225 horse serum samples in China and found EqPV-H, EqPV-CSF and EqCoPV viremia in 7.6% (17/225), 2.7% (6/225) and 2.2% of samples (5/225), respectively. We also obtained the complete genomes of one EqPV-H strain, six EqPV-CSF strains and one EqCoPV strain. After phylogenetic analysis of the EqPVs, we found that EqPV-CSF and EqCoPV may have evolved from the same ancestor. The EqPV-CSF strains (E111 and A27) and EqCoPV strain (F124) were genetically similar to foreign strains, but the EqPV-CSF strains (B48, E96, C61 and F146) comprised unique clades. This study determined the prevalence of three EqPVs in Chinese horses and analyzed the genetic characteristics of EqPVs prevalent strains in Chinese horse herds. Our data provide a theoretical basis for follow-up research on the prevention and control of EqPVs.

5.
Exp Anim ; 2022 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-36543206

RESUMO

Nonhuman primates are used extensively in a variety of non-clinical safety evaluation studies of new drugs. In those studies, intravenous infusion is a common treatment method, non-invasive telemetry system is usually used for cardiovascular safety and pharmacology evaluation, and blood samples are repeated collected for various analysis. Intravenous infusion, vest wearing and repeated bleeding can caused the stress response in cynomolgus monkeys, which may lead to changes on clinical pathology parameters in cynomolgus monkeys. Here, we aimed to test the effectiveness of the above operations on clinical pathology parameters in cynomolgus monkeys. 0.9% sodium chloride injection was administrated to 20 monkeys (10 animals/sex) via intravenous infusion on Day 1 and Day 10. Each animal wore the vest before each dosing, the vest was removed at 24 hr after each dosing. Blood samples were collected pre-dosing, at 2 min, 24 hr, 48 hr, 72 hr, and 168 hr after each dosing. As compared to the pre-dosing (D -1) values, increased reticulocytes (RET% and RET#) and decreased erythrocytes (RBC, HGB, and HCT) were noted after dosing. The loss of erythrocytes and increases of reticulocytes were considered to the related to the repeated bleeding. Increased leukocytes (WBC, NEUT#, and NEUT%) and platelets (MPV and PDW) were noted at 2 min or 24 hr post dose. Increased AST, DBIL, CK, CRP, and hsTnI and decreased P were noted at 2 min to 72 hr post dose.

6.
Adv Mater ; : e2206997, 2022 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-36440651

RESUMO

One central challenge in understanding phonon thermal transport is a lack of experimental tools to investigate frequency-resolved phonon transport. Although recent advances in computation lead to frequency-resolved information, it is hindered by unknown defects in bulk regions and at interfaces. Here, a framework that can uncover microscopic phonon transport information in heterostructures is presented, integrating state-of-the-art ultrafast electron diffraction (UED) with advanced scientific machine learning (SciML). Taking advantage of the dual temporal and reciprocal-space resolution in UED, and the ability of SciML to solve inverse problems involving O ( 10 3 ) $\mathcal{O}({10^3})$ coupled Boltzmann transport equations, the frequency-dependent interfacial transmittance and frequency-dependent relaxation times of the heterostructure from the diffraction patterns are reliably recovered. The framework is applied to experimental Au/Si UED data, and a transport pattern beyond the diffuse mismatch model is revealed, which further enables a direct reconstruction of real-space, real-time, frequency-resolved phonon dynamics across the interface. The work provides a new pathway to probe interfacial phonon transport mechanisms with unprecedented details.

7.
Nano Lett ; 2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-36450036

RESUMO

Relaxor ferroelectrics have been intensely studied for decades based on their unique electromechanical responses which arise from local structural heterogeneity involving polar nanoregions or domains. Here, we report first studies of the ultrafast dynamics and reconfigurability of the polarization in freestanding films of the prototypical relaxor 0.68PbMg1/3Nb2/3O3-0.32PbTiO3 (PMN-0.32PT) by probing its atomic-scale response via femtosecond-resolution, electron-scattering approaches. By combining these structural measurements with dynamic phase-field simulations, we show that femtosecond light pulses drive a change in both the magnitude and direction of the polarization vector within polar nanodomains on few-picosecond time scales. This study defines new opportunities for dynamic reconfigurable control of the polarization in nanoscale relaxor ferroelectrics.

8.
Adv Mater ; : e2202841, 2022 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-36189841

RESUMO

Magnetism in topological materials creates phases exhibiting quantized transport phenomena with potential technological applications. The emergence of such phases relies on strong interaction between localized spins and the topological bands, and the consequent formation of an exchange gap. However, this remains experimentally unquantified in intrinsic magnetic topological materials. Here, this interaction is quantified in MnBi2 Te4 , a topological insulator with intrinsic antiferromagnetism. This is achieved by optically exciting Bi-Te p states comprising the bulk topological bands and interrogating the consequent Mn 3d spin dynamics, using a multimodal ultrafast approach. Ultrafast electron scattering and magneto-optic measurements show that the p states demagnetize via electron-phonon scattering at picosecond timescales. Despite being energetically decoupled from the optical excitation, the Mn 3d spins, probed by resonant X-ray scattering, are observed to disorder concurrently with the p spins. Together with atomistic simulations, this reveals that the exchange coupling between localized spins and the topological bands is at least 100 times larger than the superexchange interaction, implying an optimal exchange gap of at least 25 meV in the surface states. By quantifying this exchange coupling, this study validates the materials-by-design strategy of utilizing localized magnetic order to manipulate topological phases, spanning static to ultrafast timescales.

9.
Front Public Health ; 10: 980973, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36062130

RESUMO

Background: Change in obesity risk could be related to shift in high blood pressure (HBP) risk, while individualized influence of weight change on high blood pressure is in need of exploration. Methods: A total of 16,446 children (53.47% boys) and 13,9021 effective annual measurements from 2006 to 2020 were recruited. Children's weight status, both at baseline and endpoint, was categorized as underweight, normal, overweight, and obese according to the age and sex-specific Body Mass Index z scores. HBP at late adolescence was defined with the last two measurements for each child. Populational attributable risk (PAR) of weight trait on HBP risk was calculated. Results: Compared to children who maintained normal weight during follow-up, staying obese was associated with the highest HBP risk with OR of 6.39 (95% CI: 4.46, 9.15; p < 0.001) and PAR of 28.71% (95% CI: 21.58, 35.54) in boys, and OR of 6.12 (95% CI: 2.80, 13.37; p < 0.001) and PAR of 12.75% (95% CI: 4.29, 21.02) in girls. Returning from obese to normal weight was associated with lowered HBP risk, with ORs of 1.07 (95% CI: 0.69, 1.66; p = 0.771) in boys and 0.73 (95% CI: 0.25, 2.12; p = 0.566) in girls. Conclusion: Weight loss program could be effective to reduce HBP risk during school age, while the underlying mechanism needs further exploration.


Assuntos
Hipertensão , Adolescente , Pressão Sanguínea/fisiologia , Criança , China/epidemiologia , Feminino , Humanos , Hipertensão/epidemiologia , Estudos Longitudinais , Masculino , Obesidade/epidemiologia
10.
Front Endocrinol (Lausanne) ; 13: 882840, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35937794

RESUMO

Introduction: The relationship between the characteristics of puberty growth and the stature (height and overweight and obesity) in late adolescence was not clear. We aimed to explore the effects of puberty growth patterns on the stature in late adolescence. Methods: A total of 13,143 children from a longitudinal cohort from 2006 to 2016 in Zhongshan city of China were included. The Preece-Baines growth curve was fitted for each individual child, and the age at peak height velocity (APHV), peak height velocity (PHV), and age at take-off (TOA) were obtained from the Preece-Baines model. To compare the difference in height in late adolescence (at 18 years old) at different pubertal height growth patterns (height spurt timing, intensity, and duration), the height at baseline was matched by using the propensity score matching. The log-binomial model was applied to assess the association between the three pubertal height growth patterns (timing, intensity, and duration) and overweight and obesity status in late adolescence, controlling the urbanity and body mass index (BMI) at baseline. Results: After matching the baseline height, boys and girls in three pubertal patterns with early timing (P < 0.01), small intensity (P < 0.01), and short duration (P < 0.01) of height spurt had the lowest final height in the late adolescence. A 16% increase and 45% increase of risk for overweight and obesity were significantly associated with the early APHV in boys and girls, respectively, relative risk (RR) in boys, 1.16(95% confidence interval, CI: 1.03-1.30), P = 0.011; RR in girls, 1.45(1.21-1.75), P < 0.001. A 21% increase and 59% increase of risk for overweight and obesity were significantly associated with small PHV in boys and girls, respectively, RR in boys, 1.21(1.07-1.36), P < 0.001; RR in girls, 1.59(1.30-1.95), P < 0.001; and an 80% increase of risk for overweight and obesity with small spurt duration in girls (RR = 1.80; 95% CI: 1.49, 2.18; P < 0.001). Conclusion: Pubertal growth patterns, including earlier puberty onset timing, smaller puberty intensity, and shorter puberty spurt duration, had a positive association with lower height risks and higher overweight and obesity risks in late adolescence.


Assuntos
Sobrepeso , Puberdade , Adolescente , Estatura , Criança , Feminino , Humanos , Estudos Longitudinais , Masculino , Obesidade , Sobrepeso/epidemiologia
11.
Medicine (Baltimore) ; 101(34): e30015, 2022 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-36042667

RESUMO

To evaluate the effects of Chêneau bracing on Cobb's angle (CA) and spinopelvic parameters in adolescent idiopathic scoliosis (AIS) patients. In this retrospective study, we evaluated 51 AIS patients who received Chêneau bracing treatment between January 2020 and August 2021. The prebracing and in-bracing radiographs were analyzed about the spinopelvic parameters. The CA, pelvic coronal obliquity angle, thoracolumbar kyphosis (TLK), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), sagittal vertical angle, and coronal vertical angle were measured. Paired t-test was used to compare prebracing and in-bracing spinopelvic parameters. The Pearson correlation analysis was used to identify the relationships between the variations in the spinopelvic parameters. The mean age at the initiation of bracing was 13.6 ± 1.5 years. The mean prebracing CA was 24.0° ± 6.3°. There were no statistically significant differences between prebracing and in-bracing measurements of sagittal and coronal vertical angles. However, there were statistically significant differences between the prebracing and in-bracing measurements of the CA, pelvic coronal obliquity angle, TLK, LL, PT, and SS. A significant correlation was observed between PT and thoracolumbar kyphosis variations in the sagittal plane. The pelvic coronal obliquity angle variation was correlated to the prebracing pelvic coronal obliquity angle in the coronal plane. Chêneau's bracing effects of AIS can be extended to the pelvis. Affected by the Chêneau brace, the pelvis should be retro-rotated correspondingly to TLK hyperkyphosis on the sagittal plane, whereas in the coronal plane, pelvic obliquity was improved independently. The effect of Chêneau braces on the pelvic parameters should be fully considered before bracing treatment.


Assuntos
Cifose , Lordose , Escoliose , Adolescente , Braquetes/efeitos adversos , Humanos , Cifose/diagnóstico por imagem , Cifose/etiologia , Cifose/terapia , Lordose/complicações , Vértebras Lombares/diagnóstico por imagem , Pelve/diagnóstico por imagem , Estudos Retrospectivos , Escoliose/complicações , Escoliose/diagnóstico por imagem , Escoliose/terapia
12.
Vet Med Sci ; 8(5): 2076-2085, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35894780

RESUMO

OBJECTIVE: In quantitative reverse transcription-polymerase chain reaction (RT-qPCR) studies, the selection and validation of reference genes are crucial for the accurate analysis of MicroRNAs (miRNAs) expression. In this work, the optimal reference genes for RT-qPCR normalisation in plasma samples of rat middle cerebral artery occlusion (MCAO) models were identified. METHODS: Six rat MCAO models were established. Blood samples were collected before modelling and approximately 16-24 h after modelling. Two commonly used reference genes (U6 and 5S) and three miRNAs (miR-24, miR-122 and miR-9a) were selected as candidate reference genes, and the expression of these genes was detected with RT-qPCR. The acquired data were analysed using geNorm, Normfinder, BestKeeper, RefFinder and comparative delta threshold cycle statistical models. RESULTS: The analysed results consistently showed that miR-24 was the most stably expressed reference gene. The 'optimal combination' calculated by geNorm was miR-24, U6 and5S. The expression level of the target gene miR124 was similar when the most stable reference gene miR-24 or the 'optimal combination' was used as a reference gene. However, compared with miR24 or the 'optimal combination', the less stable reference genes influenced the fold change and the data accuracy with a large standard deviation. CONCLUSION: These results confirmed the importance of selecting suitable reference genes for normalisation to obtain reliable results in RT-qPCR studies and demonstrated that the identified reference gene miR-24 or the 'optimal combination' could be used as an internal control for gene expression analysis in the rat MCAO model.


Assuntos
MicroRNAs , Doenças dos Roedores , Animais , Infarto da Artéria Cerebral Média/genética , Infarto da Artéria Cerebral Média/veterinária , MicroRNAs/genética , Ratos , Reação em Cadeia da Polimerase em Tempo Real/métodos , Reação em Cadeia da Polimerase em Tempo Real/veterinária
13.
Environ Sci Pollut Res Int ; 29(48): 73262-73270, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35622291

RESUMO

Evidence on the effects of exposure to ambient gaseous pollutants on children's vision was consistently scarce. We aimed to explore the effect of ambient gaseous pollutant exposure on the incidence of visual impairment (VI) in children. From 2005 to 2018, a total of 340,313 children without VI participated in a longitudinal and two-center dynamic cohort. The logMAR acuity was used to assess visual function. The space-time extremely randomized trees model was used to estimate SO2 and CO exposures levels. The association between SO2 and CO and VI risks among children was assessed using a proportional hazards model with a restricted cubic spline. Subgroup analyses stratified by gender and grades were used to investigate the differences in an association of SO2 and CO exposures with childhood VI. A total of 158381 (46.54%) children experienced an new incident VI. A ten-unit (10 µg/m3) increase in SO2 exposure concentrations was significantly associated with a 1.70 times higher risk of childhood VI. In addition, a 0.1-unit (0.1 mg/m3) increase in CO exposure was significantly associated with a 1.22 times higher risk of childhood VI. The positive association between ambient gaseous pollutants (including SO2 and CO exposures) and childhood VI risks remained even after adjusting for other environmental variables. An increase in the incidence of VI in children was positively linked to SO2 and CO exposure. Such evidence might aid governments in developing strategies to interfere with children's eyesight by decreasing air pollution and changing school curricula.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Poluentes Ambientais , Adolescente , Poluentes Atmosféricos/análise , Poluição do Ar/análise , Criança , China/epidemiologia , Estudos de Coortes , Exposição Ambiental/análise , Poluentes Ambientais/análise , Humanos , Incidência , Dióxido de Nitrogênio/análise , Material Particulado/análise , Dióxido de Enxofre/análise , Transtornos da Visão
14.
Sci Adv ; 8(13): eabn0523, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35363518

RESUMO

Magnetic nanoparticles such as FePt in the L10 phase are the bedrock of our current data storage technology. As the grains become smaller to keep up with technological demands, the superparamagnetic limit calls for materials with higher magnetocrystalline anisotropy. This, in turn, reduces the magnetic exchange length to just a few nanometers, enabling magnetic structures to be induced within the nanoparticles. Here, we describe the existence of spin-wave solitons, dynamic localized bound states of spin-wave excitations, in FePt nanoparticles. We show with time-resolved x-ray diffraction and micromagnetic modeling that spin-wave solitons of sub-10 nm sizes form out of the demagnetized state following femtosecond laser excitation. The measured soliton spin precession frequency of 0.1 THz positions this system as a platform to develop novel miniature devices.

15.
Sci Total Environ ; 832: 155117, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35398425

RESUMO

Greenness could theoretically increase the impact of physical activity (PA) and reduce the adverse effects of air pollution on overweight/obesity. However, no evidence systematically compares these two pathways, especially in longitudinal studies of children and adolescent's cohort. Greenness, PA, and air pollution were assessed by Normalized Difference Vegetation Index (NDVI), International Physical Activity Short Form, and 7 pollutants (PM1, PM2.5, PM10, SO2, NO2, CO, and O3). Each exposure was divided into low-/high-level groups based on the 50% quantile. Proportional hazards and logistic regression model were used to assess the associations of greenness, PA, pollutants with overweight/obesity. The incidence of overweight/obesity was 1.98% in the national survey, and the cumulative incidence and incidence density were 12.76% and 3.43 per 100 person-year in the dynamic cohort, separately. An increase of 0.1 units in NDVI was associated with a 12% lower risk of overweight/obesity, but no significant link between PA and incidence was observed. The HRs of the high-level of PM1, PM2.5, PM10, SO2, NO2, CO, and O3 on the risk of overweight/obesity were 2.21, 2.63, 1.88, 2.38, 1.33, 2.43, and 1.33 in the low-level of greenness, which was higher than those in the high-level of greenness. The AFs of PM1, PM2.5, PM10, SO2, NO2, CO, and O3 were 25.58%, 44.37%, 22.96%, 29.15%, 11.55%, 29.50%, and 10.92% in the low-level of greenness, which simultaneously was higher than those in the high-level of greenness. Moreover, the risk of overweight/obesity associated with high-level of greenness in the high-level of PM10, SO2, CO were 0.83, 0.81, and 0.83 respectively. Our findings confirmed that greenness has a moderating effect on the effects of air pollutants on childhood overweight/obesity especially in heavy-industry areas where PM10, SO2, and CO are the major pollutants, although it did not influence the association between PA and overweight/obesity risks.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Adolescente , Poluentes Atmosféricos/análise , Criança , China/epidemiologia , Exposição Ambiental/análise , Exercício Físico , Humanos , Dióxido de Nitrogênio/análise , Obesidade/induzido quimicamente , Obesidade/epidemiologia , Sobrepeso/induzido quimicamente , Sobrepeso/epidemiologia , Material Particulado/análise
16.
Front Nutr ; 9: 785863, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35387193

RESUMO

Background: Current reference systems using body mass index (BMI) or BMI z-scores to estimate overweight and obesity risk in adolescents are complex to use. An easy and effective measure and cutoffs such as the tri-ponderal mass index (TMI) are in need for parents and grassroots health workers. Objective: The aim of this study was to test whether cohort-derived TMI could be efficient for obesity prediction and to find out whether simplified TMI cutoffs could be used in the prediction. Methods: Data were obtained from a 12-year retrospective growth cohort generated in Guangdong, China. A total of 17,815 children (53.9% were boys) with 151,879 follow-ups conducted annually between 2005 and 2016 were involved. Late adolescent overweight and obesity were defined based on the BMI z-score (WHO 2007 growth reference) of the last measurement, which happened at the mean age of 17.2 (SD: 0.7) for both sexes. Analysis of the area under the curve (AUC) of the receiver operating characteristic curves was used to find the most appropriate cutoff. Results: In total, 9,604 boys and 8,211 girls were included in the final analysis. TMI cutoffs performed better than WHO BMI cutoffs in the prediction of late adolescent overweight and obesity, with all corresponding AUCs <0.7. The simplified TMI cutoffs used to predict late adolescent overweight and obesity were 13.1 and 14.1 kg/m3 for children aged 7 to 15 years, respectively, with the corresponding AUCs ranging from 0.7315 (standard error, SE: 0.0132) to 0.9367 (SE: 0.0052). The cutoffs for predicting late adolescent overweight and obesity for children aged 16 to 18 years were 14.0 and 15.8 kg/m3, respectively, with the corresponding AUCs ranging from 0.9189 (SE: 0.0048) to 0.9841 (95% CI: 0.0027). Conclusion: Tri-ponderal mass index with the ease of administration in practice could be a promising alternative screening tool to BMI for the prediction of late adolescent overweight and obesity.

17.
Nat Commun ; 13(1): 1929, 2022 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-35396393

RESUMO

The emergence of magnetism in quantum materials creates a platform to realize spin-based applications in spintronics, magnetic memory, and quantum information science. A key to unlocking new functionalities in these materials is the discovery of tunable coupling between spins and other microscopic degrees of freedom. We present evidence for interlayer magnetophononic coupling in the layered magnetic topological insulator MnBi2Te4. Employing magneto-Raman spectroscopy, we observe anomalies in phonon scattering intensities across magnetic field-driven phase transitions, despite the absence of discernible static structural changes. This behavior is a consequence of a magnetophononic wave-mixing process that allows for the excitation of zone-boundary phonons that are otherwise 'forbidden' by momentum conservation. Our microscopic model based on density functional theory calculations reveals that this phenomenon can be attributed to phonons modulating the interlayer exchange coupling. Moreover, signatures of magnetophononic coupling are also observed in the time domain through the ultrafast excitation and detection of coherent phonons across magnetic transitions. In light of the intimate connection between magnetism and topology in MnBi2Te4, the magnetophononic coupling represents an important step towards coherent on-demand manipulation of magnetic topological phases.

18.
Lab Chip ; 22(7): 1365-1373, 2022 03 29.
Artigo em Inglês | MEDLINE | ID: mdl-35234235

RESUMO

We report on the design and testing of glass nozzles used to produce liquid sheets. The sheet nozzles use a single converging channel chemically etched into glass wafers by standard lithographic methods. Operation in ambient air and vacuum was demonstrated. The measured sheet thickness ranges over one order of magnitude with the smallest thickness of 250 nm and the largest of 2.5 µm. Sheet thickness was shown to be independent of liquid flow rate, and dependent on the nozzle outlet area. Sheet surface roughness was dependent on nozzle surface finish and was on the order of 10 nm for polished nozzles. Electron transmission data is presented for various sheet thicknesses near the MeV mean free path and the charge pair distribution function for D2O is determined from electron scattering data.


Assuntos
Vidro , Vácuo
19.
Phys Rev Lett ; 128(3): 036401, 2022 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-35119886

RESUMO

Hysteresis underlies a large number of phase transitions in solids, giving rise to exotic metastable states that are otherwise inaccessible. Here, we report an unconventional hysteretic transition in a quasi-2D material, EuTe_{4}. By combining transport, photoemission, diffraction, and x-ray absorption measurements, we observe that the hysteresis loop has a temperature width of more than 400 K, setting a record among crystalline solids. The transition has an origin distinct from known mechanisms, lying entirely within the incommensurate charge density wave (CDW) phase of EuTe_{4} with no change in the CDW modulation periodicity. We interpret the hysteresis as an unusual switching of the relative CDW phases in different layers, a phenomenon unique to quasi-2D compounds that is not present in either purely 2D or strongly coupled 3D systems. Our findings challenge the established theories on metastable states in density wave systems, pushing the boundary of understanding hysteretic transitions in a broken-symmetry state.

20.
Nat Commun ; 13(1): 1055, 2022 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-35217665

RESUMO

Plasticity is ubiquitous and plays a critical role in material deformation and damage; it inherently involves the atomistic length scale and picosecond time scale. A fundamental understanding of the elastic-plastic deformation transition, in particular, incipient plasticity, has been a grand challenge in high-pressure and high-strain-rate environments, impeded largely by experimental limitations on spatial and temporal resolution. Here, we report femtosecond MeV electron diffraction measurements visualizing the three-dimensional (3D) response of single-crystal aluminum to the ultrafast laser-induced compression. We capture lattice transitioning from a purely elastic to a plastically relaxed state within 5 ps, after reaching an elastic limit of ~25 GPa. Our results allow the direct determination of dislocation nucleation and transport that constitute the underlying defect kinetics of incipient plasticity. Large-scale molecular dynamics simulations show good agreement with the experiment and provide an atomic-level description of the dislocation-mediated plasticity.

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