Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.124
Filtrar
1.
Front Psychiatry ; 15: 1335554, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38957739

RESUMO

Background: Mobile phone addiction (MPA) greatly affects the biological clock and sleep quality and is emerging as a behavioral disorder. The saliva microbiota has been linked to circadian rhythms, and our previous research revealed dysrhythmic saliva metabolites in MPA subjects with sleep disorders (MPASD). In addition, acupuncture had positive effects. However, the dysbiotic saliva microbiota in MPASD patients and the restorative effects of acupuncture are unclear. Objectives: To probe the circadian dysrhythmic characteristics of the saliva microbiota and acupunctural restoration in MPASD patients. Methods: MPASD patients and healthy volunteers were recruited by the Mobile Phone Addiction Tendency Scale (MPATS) and the Pittsburgh Sleep Quality Index (PSQI). Saliva samples were collected every 4 h for 72 h. After saliva sampling, six MPDSD subjects (group M) were acupuncturally treated (group T), and subsequent saliva sampling was conducted posttreatment. Finally, all the samples were subjected to 16S rRNA gene sequencing and bioinformatic analysis. Results: Significantly increased MPATS and PSQI scores were observed in MPDSD patients (p< 0.01), but these scores decreased (p<0.001) after acupuncture intervention. Compared with those in healthy controls, the diversity and structure of the saliva microbiota in MPASD patients were markedly disrupted. Six genera with circadian rhythms were detected in all groups, including Sulfurovum, Peptostreptococcus, Porphyromonas and Prevotella. There were five genera with circadian rhythmicity in healthy people, of which the rhythmicities of the genera Rothia and Lautropia disappeared in MPASD patients but effectively resumed after acupuncture intervention. Conclusions: This work revealed dysrhythmic salivary microbes in MPASD patients, and acupuncture, as a potential intervention, could be effective in mitigating this ever-rising behavioral epidemic.

2.
Artigo em Inglês | MEDLINE | ID: mdl-38959195

RESUMO

Background: Posterior fossa craniotomy is commonly performed for various pathologies. However, intra-cranial infection following craniotomy causes morbidity. Pseudomeningocele is one of the main complications following posterior fossa operation. This study aimed to test the hypothesis that the risk of intra-cranial infection is increased in patients who undergo posterior fossa craniotomy with pseudomeningocele compared with those without pseudomeningocele. Methods: We retrospectively analyzed the data of patients undergoing posterior fossa craniotomy for the management of neurological pathologies at our institute from 2011 to 2020. A total of 308 craniotomies were included, and the primary outcome of interest was the occurrence of intra-cranial infection. Standard statistical methods were used to explore associations between several parameters, including pseudomeningocele, intra-cranial infection, and wound leak. Results: Of the 308 craniotomies, 41 (13.3%) developed intra-cranial infection and 59 (19.2%) involved pseudomeningocele. Of cases involving pseudomeningocele, 27 (45.8%) developed an intra-cranial infection compared with only 14 of 249 without pseudomeningocele (5.6%; p < 0.001). In the multi-variable analysis, pseudomeningocele was associated with intra-cranial infection (odds ratio [OR] 8.56; 95% confidence interval [CI] 3.145-23.299; p < 0.001) and wound leak (OR 91.339; 95% CI 10.437-799.364; p < 0.001). Conclusion: The findings indicate that patients undergoing posterior fossa craniotomy are at a greater risk of intra-cranial infection if there is pseudomeningocele after the operation.

3.
Sci Rep ; 14(1): 15368, 2024 07 04.
Artigo em Inglês | MEDLINE | ID: mdl-38965410

RESUMO

To detect and analyze the changes of microorganisms in expressed prostatic secretion (EPS) of patients with IIIB prostatitis before and after low-intensity pulsed ultrasound (LIPUS) treatment, and to explore the mechanism of LIPUS in the treatment of chronic prostatitis (CP). 25 patients (study power was estimated using a Dirichlet-multinomial approach and reached 96.5% at α = 0.05 using a sample size of 25) with IIIB prostatitis who were effective in LIPUS treatment were divided into two groups before and after LIPUS treatment. High throughput second-generation sequencing technique was used to detect and analyze the relative abundance of bacterial 16 s ribosomal variable regions in EPS before and after treatment. The data were analyzed by bioinformatics software and database, and differences with P < 0.05 were considered statistically significant. Beta diversity analysis showed that there was a significant difference between groups (P = 0.046). LEfSe detected four kinds of characteristic microorganisms in the EPS of patients with IIIB prostatitis before and after LIPUS treatment. After multiple comparisons among groups by DESeq2 method, six different microorganisms were found. LIPUS may improve patients' clinical symptoms by changing the flora structure of EPS, stabilizing and affecting resident bacteria or opportunistic pathogens.


Assuntos
Próstata , Prostatite , Ondas Ultrassônicas , Humanos , Masculino , Prostatite/terapia , Prostatite/microbiologia , Prostatite/metabolismo , Próstata/microbiologia , Próstata/metabolismo , Próstata/patologia , Adulto , Bactérias/metabolismo , Bactérias/genética , Pessoa de Meia-Idade , Terapia por Ultrassom/métodos , Microbiota , RNA Ribossômico 16S/genética
4.
Discov Oncol ; 15(1): 255, 2024 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-38955924

RESUMO

CD320, which is a transmembrane protein responsible for facilitating the absorption of vitamin B12, plays a key role in this process. However, the relationships between CD320 and immune cell infiltration levels remain unclear, with limited studies investigating the diagnostic and prognostic significance of CD320 in hepatocellular carcinoma. We used various databases, including the TIMER, GEPIA, UALCAN and TCGA databases to investigate the expression levels of CD320 in hepatocellular carcinoma. Subsequently, we analyzed the prognosis of hepatocellular carcinoma patients with different expression levels of CD320. Furthermore, we also performed Western blot, immunohistochemistry, and immunofluorescence analyses to validate the results of the database analysis. Finally, the functions of CD320 in hepatocellular carcinoma were also confirmed via relevant cell experiments and angiogenesis assays. We found that CD320 expression was significantly upregulated in tumor vascular endothelial cells. Moreover, the knockdown of CD320 led to a reduction in angiogenesis in endothelial cells. Increased expression of CD320 was also correlated with a poor prognosis in patients with hepatocellular carcinoma, which suggested that CD320 may be a potential prognostic marker. Finally, TIMER analysis demonstrated that the infiltration of six immune cell types was significantly associated with high expression levels of CD320 in hepatocellular carcinoma. Herein, we demonstrated that CD320 may play an important role in angiogenesis in hepatocellular carcinoma. These findings suggested that CD320 may be a potential clinical prognostic marker and immunotherapy target for hepatocellular carcinoma.

5.
Commun Biol ; 7(1): 827, 2024 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-38972908

RESUMO

The "hologenome" concept is an increasingly popular way of thinking about microbiome-host for marine organisms. However, it is challenging to track hologenome dynamics because of the large amount of material, with tracking itself usually resulting in damage or death of the research object. Here we show the simple and efficient holo-2bRAD approach for the tracking of hologenome dynamics in marine invertebrates (i.e., scallop and shrimp) from one holo-2bRAD library. The stable performance of our approach was shown with high genotyping accuracy of 99.91% and a high correlation of r > 0.99 for the species-level profiling of microorganisms. To explore the host-microbe association underlying mass mortality events of bivalve larvae, core microbial species changed with the stages were found, and two potentially associated host SNPs were identified. Overall, our research provides a powerful tool with various advantages (e.g., cost-effective, simple, and applicable for challenging samples) in genetic, ecological, and evolutionary studies.


Assuntos
Organismos Aquáticos , Animais , Organismos Aquáticos/genética , Invertebrados/genética , Invertebrados/fisiologia , Microbiota , Polimorfismo de Nucleotídeo Único
6.
Trials ; 25(1): 432, 2024 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-38956697

RESUMO

BACKGROUND: Norepinephrine and phenylephrine are commonly used vasoactive drugs to treat hypotension during the perioperative period. The increased release of endogenous norepinephrine elicits prothrombotic changes, while parturients are generally in a hypercoagulable state. Therefore, this trial aims to investigate whether there is a disparity between equivalent doses of prophylactic norepinephrine infusion and phenylephrine infusion on prothrombotic response in patients undergoing cesarean section under spinal anesthesia. METHODS: Sixty-six eligible parturients will be recruited for this trial and randomly assigned to the norepinephrine or phenylephrine group. The "study drug" will be administered at a rate of 15 ml/h starting from the intrathecal injection. The primary outcome are plasma coagulation factor VIII activity (FVIII: C), fibrinogen, and D-dimer levels. The secondary outcomes include hemodynamic variables and umbilical artery blood pH value. DISCUSSION: Our study is the first trial comparing the effect of norepinephrine and phenylephrine on prothrombotic response in patients undergoing cesarean section under spinal anesthesia. Positive or negative results will all help us better understand the impact of vasoactive drugs on patients. If there are any differences, this trial will provide new evidence for maternal choice of vasoactive medications in the perioperative period. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCTR2300077164. Registered on 1 November 2023. https://www.chictr.org.cn/ .


Assuntos
Anestesia Obstétrica , Raquianestesia , Cesárea , Norepinefrina , Fenilefrina , Ensaios Clínicos Controlados Aleatórios como Assunto , Vasoconstritores , Humanos , Cesárea/efeitos adversos , Raquianestesia/efeitos adversos , Feminino , Norepinefrina/sangue , Método Duplo-Cego , Gravidez , Fenilefrina/administração & dosagem , Vasoconstritores/uso terapêutico , Anestesia Obstétrica/efeitos adversos , Anestesia Obstétrica/métodos , Adulto , Produtos de Degradação da Fibrina e do Fibrinogênio/metabolismo , Produtos de Degradação da Fibrina e do Fibrinogênio/análise , Fator VIII , Resultado do Tratamento , Coagulação Sanguínea/efeitos dos fármacos , Hemodinâmica/efeitos dos fármacos
7.
Surg Endosc ; 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-39009733

RESUMO

BACKGROUND: The caudate lobe (S1) of the liver, due to its deep central position, presents a formidable challenge for laparoscopic resection. Historical skepticism about laparoscopic approaches has been overshadowed by advancements in technology and technique, with recent studies showing comparable outcomes to open surgery. METHODS: This paper introduces the "Easy First" technique and the Sextet strategies for laparoscopic hepatic caudate lobectomy. The strategies include meticulous preoperative planning, optimal trocar placement, and team positioning, tailored to the anatomical complexities of the caudate lobe. RESULTS: With a 0% conversion and mortality rate, our series demonstrates the safety of the "Easy First" technique. The Sextet strategies have been instrumental in navigating the technical challenges, emphasizing the importance of patient selection and surgeon expertise. CONCLUSION: The "Easy First" technique, with its structured approach and the Sextet strategies, offers a replicable method for laparoscopic caudate lobectomy. It underscores the need for stringent patient selection, advanced technical skill, and high-volume center expertise to ensure procedural success and patient safety.

8.
BMJ Open ; 14(7): e083202, 2024 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-38991676

RESUMO

INTRODUCTION: Peripheral vasodilation causes a redistribution of body temperature from the core to the periphery, resulting in shivering and hypothermia. These are normal pathological and physiological processes during spinal anaesthesia. Two drugs, norepinephrine and phenylephrine, have peripheral vasoconstrictive effects. It is unclear the effects of norepinephrine and phenylephrine on shivering and hypothermia in patients undergoing caesarean section under spinal anaesthesia. METHODS ANALYSIS: 240 eligible parturients will be recruited for this randomised, double-blind, controlled trial and randomly assigned to either the norepinephrine or phenylephrine groups. The primary outcome will be the incidence of shivering while secondary outcomes will include the severity of shivering, rectal temperature, incidence of hypothermia and umbilical artery blood pH value. ETHICS AND DISSEMINATION: The Institutional Ethics Committee of The Second People's Hospital of Hefei approved the trial protocol (ID: 2023-093). The results will be published in a compliant journal. The original data will be released in December 2029 on the ResMan original data-sharing platform of the China Clinical Trial Registry (http://www.medresman.org.cn). TRIAL REGISTRATION NUMBER: ChiCTR2300077164.


Assuntos
Raquianestesia , Cesárea , Hipotermia , Norepinefrina , Fenilefrina , Estremecimento , Centros de Atenção Terciária , Humanos , Raquianestesia/métodos , Raquianestesia/efeitos adversos , Estremecimento/efeitos dos fármacos , Cesárea/efeitos adversos , Feminino , Método Duplo-Cego , Gravidez , Norepinefrina/uso terapêutico , China/epidemiologia , Hipotermia/prevenção & controle , Fenilefrina/uso terapêutico , Adulto , Anestesia Obstétrica/métodos , Anestesia Obstétrica/efeitos adversos , Vasoconstritores/uso terapêutico , Ensaios Clínicos Controlados Aleatórios como Assunto
9.
Materials (Basel) ; 17(13)2024 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-38998409

RESUMO

This paper introduces an electromagnetic structure utilizing the controllable mechanical properties of magnetorheological elastomer (MRE) materials through magnetic flux. An adaptive elastic foundation composed of these materials is explored for vibration reduction and frequency modulation. This study investigates these effects using both a single-mass model and a coupled human-seat model. For objects supported by the adaptive elastic foundation, increasing the magnetic flux enhances the stiffness and damping, thereby significantly reducing the peak response while slightly increasing the resonance frequency. Strategies such as increasing the magnetic flux, reducing the object mass, and minimizing the system's degrees of freedom and internal damping contribute to enhancing the vibration reduction and frequency modulation in the adaptive elastic foundation. The simulation results indicate that for a seated human (weighing between 72.4 kg and 88.4 kg), the adaptive elastic foundation reduces the head peak response by approximately 15.7% and increases the resonance frequency by approximately 3.4% at a magnetic flux of 138 mT.

10.
MedComm (2020) ; 5(6): e571, 2024 Jun.
Artigo em Catalão | MEDLINE | ID: mdl-38840772

RESUMO

Iron overload is common in cardiovascular disease, it is also the factor that drives ferroptosis. Noncoding RNAs play an important role in heart disease; however, their regulatory role in iron overload-mediated ferroptosis remains much unknown. In our study, the iron overload model in mice was constructed through a high-iron diet, and ammonium iron citrate  treatment was used to mimic iron overload in vitro. We found iron overload induced ferroptosis in cardiomyocytes, which was dependent on the high expression of transferrin receptor (TFRC). MiR-31-5p was downregulated during iron overload; it inhibited cardiomyocyte ferroptosis by targeting TFRC. CircPIK3C2A, a highly expressed circRNA in the heart, was upregulated when iron was overloaded. CircPIK3C2A enhanced the expression of TFRC by sponging miR-31-5p and promoted ferroptosis during iron overload. Our results reveal a novel mechanistic insight into noncoding RNA-based ferroptosis and identify the circPIK3C2A/miR-31-5p/TFRC axis as a promising therapeutic target for myocardial damage.

11.
Nat Chem ; 2024 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-38844635

RESUMO

Halogenated organic pollutants (HOPs) are causing a significant environmental and human health crisis due to their high levels of toxicity, persistence and bioaccumulation. Urgent action is required to develop effective approaches for the reduction and reuse of HOPs. Whereas current strategies focus primarily on the degradation of HOPs, repurposing them is an alternative approach, albeit a challenging task. Here we discover that alkyl bromide can act as a catalyst for the transfer of chlorine using alkyl chloride as the chlorine source. We demonstrate that this approach has a wide substrate scope, and we successfully apply it to reuse HOPs that include dichlorodiphenyltrichloroethane, hexabromocyclododecane, chlorinated paraffins, chloromethyl polystyrene and poly(vinyl chloride) (PVC). Moreover, we show that the synthesis of essential non-steroidal anti-inflammatory drugs can be achieved using PVC and hexabromocyclododecane, and we demonstrate that PVC waste can be used directly as a chlorinating agent. Overall, this methodology offers a promising strategy for repurposing HOPs.

12.
Pest Manag Sci ; 2024 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-38847112

RESUMO

BACKGROUND: Plants have numerous defensive secondary metabolites to withstand insect attacks. Scoparone, which is extracted from the medicinal plant Artemisia capillaris, has potent acaricidal effects on Tetranychus cinnabarinus. Spirodiclofen, derived from a tetronic acid derivative, is a potent commercial acaricide that is extensively used globally. However, whether scoparone has synergistic effects when used in conjunction with spirodiclofen and the underlying synergistic mechanism remains unclear. RESULTS: Scoparone exhibited a potent synergistic effect when it was combined with spirodiclofen at a 1:9 ratio. Subsequently, cytochrome P450 monooxygenase (P450) activity, RNA-Seq and qPCR assays indicated that the enzyme activity of P450 and the expression of one P450 gene from T. cinnabarinus, TcCYP388A1, were significantly inhibited by scoparone and spirodiclofen + scoparone; conversely, P450 was activated in spirodiclofen-exposed mites. Importantly, RNAi-mediated silencing of the TcCYP388A1 gene markedly increased the susceptibility of spider mites to spirodiclofen, scoparone and spirodiclofen + scoparone, and in vitro, the recombinant TcCYP388A1 protein could metabolize spirodiclofen. Molecular docking and functional analyses further indicated that R117, which is highly conserved in Arachnoidea species, may be a vital specific binding site for scoparone in the mite TcCYP388A1 protein. This binding site was subsequently confirmed using mutagenesis data, which revealed that this binding site was the sole site selected by scoparone in spider mites over mammalian or fly CYP388A1. CONCLUSIONS: These results indicate that the synergistic effects of scoparone and spirodiclofen on mites occurs through the inhibition of P450 activity, thus reducing spirodiclofen metabolism. The synergistic effect of this potent natural product on the detoxification enzyme-targeted activity of commercial acaricides may offer a sustainable strategy for pest mite resistance management. © 2024 Society of Chemical Industry.

13.
Sensors (Basel) ; 24(12)2024 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-38931495

RESUMO

Video action recognition based on skeleton nodes is a highlighted issue in the computer vision field. In real application scenarios, the large number of skeleton nodes and behavior occlusion problems between individuals seriously affect recognition speed and accuracy. Therefore, we proposed a lightweight multi-stream feature cross-fusion (L-MSFCF) model to recognize abnormal behaviors such as fighting, vicious kicking, climbing over the wall, et al., which could obviously improve recognition speed based on lightweight skeleton node calculation, and improve recognition accuracy based on occluded skeleton node prediction analysis in order to effectively solve the behavior occlusion problem. The experiments show that our proposed All-MSFCF model has a video action recognition average accuracy rate of 92.7% for eight kinds of abnormal behavior recognition. Although our proposed lightweight L-MSFCF model has an 87.3% average accuracy rate, its average recognition speed is 62.7% higher than the full-skeleton recognition model, which is more suitable for solving real-time tracing problems. Moreover, our proposed Trajectory Prediction Tracking (TPT) model could real-time predict the moving positions based on the dynamically selected core skeleton node calculation, especially for the short-term prediction within 15 frames and 30 frames that have lower average loss errors.

14.
Sci Rep ; 14(1): 14458, 2024 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-38914778

RESUMO

Unmanned aerial vehicles (UAVs) have become the focus of current research because of their practicability in various scenarios. However, current local path planning methods often result in trajectories with numerous sharp or inflection points, which are not ideal for smooth UAV flight. This paper introduces a UAV path planning approach based on distance gradients. The key improvements include generating collision-free paths using collision information from initial trajectories and obstacles. Then, collision-free paths are subsequently optimized using distance gradient information. Additionally, a trajectory time adjustment method is proposed to ensure the feasibility and safety of the trajectory while prioritizing smoothness. The Limited-memory BFGS algorithm is employed to efficiently solve optimal local paths, with the ability to quickly restart the trajectory optimization program. The effectiveness of the proposed method is validated in the Robot Operating System simulation environment, demonstrating its ability to meet trajectory planning requirements for UAVs in complex unknown environments with high dynamics. Moreover, it surpasses traditional UAV trajectory planning methods in terms of solution speed, trajectory length, and data volume.

15.
Chin Neurosurg J ; 10(1): 18, 2024 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-38835088

RESUMO

BACKGROUND: This study aimed to investigate clinical features and treatment strategies for intracranial aneurysm (IA) associated with pituitary adenoma (PA). METHODS: We enrolled patients with lesions in the sellar region and age-matched general population who were confirmed with IA from two hospitals. Four types of treatment strategies were performed, which included Type I (both IA and PA were treated with surgery), Type II (IA was treated with surgery and PA was performed by non-surgical treatment), Type III (PA was performed with surgery and observation was available for IA) and Type IV (both IA and PA were performed with non-surgical treatment). RESULTS: The incidence of IA was 2.2% in the general population, 6.1% in patients with PA, 4.3% in patients with Rathke cleft cyst, 2.8% in patients with meningioma and none were found with IA in patients with craniopharyngioma. Age over 50 years (OR, 2.69; 95% CI, 1.20-6.04; P = 0.016), female (OR, 3.83, P = 0.003), and invasive tumor (OR, 3.26, P = 0.003) were associated with a higher incidence of IA in patients with PA. During the mean follow-up of 49.2 months, no patients experienced stroke, and recurrence of aneurysms and aneurysms treated with observation were stable. Of four patients with recurrence of PA, three patients were treated for type I and one patient for type III. CONCLUSIONS: Preoperative evaluation for aneurysm screening is necessary due to the high incidence of IA in PA patients. Our current treatment strategies may provide a benefit for these patients.

16.
Imeta ; 3(2): e182, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38882487

RESUMO

The Microbiome Protocols eBook (MPB) serves as a crucial bridge, filling gaps in microbiome protocols for both wet experiments and data analysis. The first edition, launched in 2020, featured 152 meticulously curated protocols, garnering widespread acclaim. We now extend a sincere invitation to researchers to participate in the upcoming 2nd version of MPB, contributing their valuable protocols to advance microbiome research.

19.
J Int Med Res ; 52(6): 3000605241259439, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38867556

RESUMO

OBJECTIVE: To determine the prevalence of cognitive impairment (CI) among middle-aged to older patients receiving maintenance haemodialysis (MHD) and to investigate the potential association between CI and physical performance. METHODS: This cross-sectional observational study enrolled participants aged 55-85 years who received MHD. Cognitive status was assessed using the Mini Mental State Examination (MMSE). Physical performance was measured by hand grip strength, the Timed Up and Go Test (TUGT) and the 4-m walking speed. Sociodemographic, clinical and laboratory parameters were recorded for each patient. RESULTS: The study included 592 patients (363 males); and of these, 126 (21.3%) were diagnosed with CI. Compared with patients with normal cognitive function, those with CI were significantly older and had significantly longer dialysis duration, lower educational level, higher Malnutrition Inflammation Score, higher depression and higher Charlson Comorbidity Index score. After adjustment for covariates, multiple regression analysis suggested that grip strength (odds ratio [OR] = 0.959, 95% confidence interval [CI] = 0.924, 0.996) and 4-m walking speed (OR = 0.161, 95% CI = 0.070, 0.368) were protective factors. TUGT (OR = 1.037, 95%CI = 1.003, 1.071) was a risk factor. CONCLUSION: Physical performance was correlated with CI and might be a significant indicator for the early identification of CI in middle-aged to older MHD patients.


Assuntos
Disfunção Cognitiva , Força da Mão , Desempenho Físico Funcional , Diálise Renal , Humanos , Masculino , Feminino , Idoso , Estudos Transversais , Disfunção Cognitiva/fisiopatologia , Disfunção Cognitiva/epidemiologia , Disfunção Cognitiva/diagnóstico , Pessoa de Meia-Idade , Idoso de 80 Anos ou mais , Força da Mão/fisiologia , Fatores de Risco , Prevalência
20.
Nanotechnology ; 35(38)2024 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-38861960

RESUMO

Magneto-controlling micro-nano materials' motion is a promising way that enable the noncontact, remote, and nondestructive controlling of their macrostructure as well as functionalities. Here, an optical microscope with an electromagnet was constructed toin-situmonitor the magneto-controlled motion process microscopically. Taking micro-nano graphite flake (MGF) as a model system, we experimentally demonstrate the key factors that influence the magneto-controlling of materials' motion. First, the product of intensity and gradient of the magnetic field (B∇B) has been confirmed as the dominant driving force and the flipping direction of the MGFs is accordingly determined by the vector direction ofB×∇B. Second, quantitatively comparative experiments further revealed that the threshold driving force has an exponential relationship with the structural aspect ratio (b/a) of MGFs. Third, the critical magneto-driving force is found as proportional to the viscosity of the solvent. Accordingly, a dynamic model is developed that describes the flip of the diamagnetic flake under external magnetic field excitation considering the shape factor. It is shown experimentally that the model accurately predicts the flip dynamics of the flake under different magnetic field conditions. In addition, we also discovered the delay effect, multiple cycle acceleration effect, and the fatigue effects due to gas adsorption in magneto-controlled MGFs flipping. These findings can be used to achieve magneto-controlling materials' macrostructure as well as their functionalities.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...