Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.127
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.
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
5.
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.

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.
Int J Surg ; 2024 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-39023809

RESUMO

BACKGROUND: Venous thromboembolism (VTE) is one of the most common and serious complications of cesarean section in parturients. Norepinephrine (NE) has been shown to activate coagulation. The aim of this study was to compare the effect of a fixed-rate prophylactic norepinephrine infusion and a fixed-rate prophylactic phenylephrine(PHE) infusion under spinal anesthesia for caesarean section on the prethrombotic response. MATERIALS AND METHODS: Sixty-six women undergoing cesarean section under spinal anesthesia were randomly assigned to the NE group or PHE group, starting simultaneously with the administration of the subarachnoid solution, a "study drug" solution containing either NE or PHE was pumped intravenously at a constant rate of 15 ml/h until the end of the operation. Plasma coagulation factor VIII activity (FVIII: C), Fibrinogen, and D-dimer levels were measured in blood samples obtained on admission to the operating theatre and at the end of the procedure. RESULTS: Compared with preoperative levels, there were no significant differences in postoperative fibrinogen and D-dimer levels in the NE group, except for a decrease in FVIII: C levels (P = 0.003). However, postoperative levels of FVIII: C (P = 0.009), fibrinogen (P = 0.035) and D-dimer (P = 0.025) were increased in the NE group compared with postoperative levels in the PHE group. CONCLUSIONS: NE does not affect the maternal prethrombotic response and can be safely used in cesarean sections. Compared with PHE infusion, NE infusion increased the level of coagulation molecules, suggesting that NE maybe more beneficial for women with high intraoperative bleeding requiring hemostasis.

8.
iScience ; 27(7): 110159, 2024 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-39021792

RESUMO

Alcohol use disorder (AUD) is a disorder of clinical and public health significance requiring novel and improved therapeutic solutions. Both environmental and genetic factors play a significant role in its pathophysiology. However, the underlying epigenetic molecular mechanisms that link the gene-environment interaction in AUD remain largely unknown. In this proof-of-concept study, we showed, for the first time, the neuroepigenetic biomarker capability of non-invasive imaging of class I histone deacetylase (HDAC) epigenetic enzymes in the in vivo brain for classifying AUD patients from healthy controls using a machine learning approach in the context of precision diagnosis. Eleven AUD patients and 16 age- and sex-matched healthy controls completed a simultaneous positron emission tomography-magnetic resonance (PET/MR) scan with the HDAC-binding radiotracer [11C]Martinostat. Our results showed lower HDAC expression in the anterior cingulate region in AUD. Furthermore, by applying a genetic algorithm feature selection, we identified five particular brain regions whose combined [11C]Martinostat relative standard uptake value (SUVR) features could reliably classify AUD vs. controls. We validate their promising classification reliability using a support vector machine classifier. These findings inform the potential of in vivo HDAC imaging biomarkers coupled with machine learning tools in the objective diagnosis and molecular translation of AUD that could complement the current diagnostic and statistical manual of mental disorders (DSM)-based intervention to propel precision medicine forward.

9.
Nat Commun ; 15(1): 6102, 2024 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-39030211

RESUMO

Visible-light photocatalysis has evolved as a powerful technique to enable controllable radical reactions. Exploring unique photocatalytic mode for obtaining new chemoselectivity and product diversity is of great significance. Herein, we present a photo-induced chemoselective 1,2-diheteroarylation of unactivated alkenes utilizing halopyridines and quinolines. The ring-fused azaarenes serve as not only substrate, but also potential precursors for halogen-atom abstraction for pyridyl radical generation in this photocatalysis. As a complement to metal catalysis, this photo-induced radical process with mild and redox neutral conditions assembles two different heteroaryl groups into alkenes regioselectively and contribute to broad substrates scope. The obtained products containing aza-arene units permit various further diversifications, demonstrating the synthetic utility of this protocol. We anticipate that this protocol will trigger the further advancement of photo-induced alkyl/aryl halides activation.

10.
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.

11.
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.

12.
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
13.
Water Res ; 260: 121900, 2024 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-38870862

RESUMO

Membrane science is the key strategy to solve water shortage in the future, and its essence is energy and mass transfer. Due to the complexity and variety of the internal structure of membrane, the energy transfer theory of membrane is still a black box theory. Herein, a new fluid mechanics principle is introduced to establish the energy fluid theory of membrane, which is translated into the energy formula: such as the initial total pressure difference (ΔP), the flow rate of fluid exiting the membrane (v1 and v2), fluid density (ρ), and energy consumption by salt resistance (NSR): { [Formula: see text] +12ρv23}. The theoretical framework is not only helpful for the data analysis of the energy transfer process of membranes, but also helps to allow for more in-depth and specific theoretical research. For instance, the relationship between NSR and the concentration difference (C) of salt can be expressed as NSR = aCb (a-product constant, b-exponential constant, R2>0.99). Hence, the basic theory can not only be widely applied to a variety of membranes with complex internal structure, but also have a profound impact on the application and research of membrane science.

14.
Small ; : e2402701, 2024 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-38874085

RESUMO

The inevitable oxidation of nickel-metal-based catalysts exposed to the air will lead to instability and poor reproducibility of a catalytic interface, which is usually ignored and greatly hinders their application for the catalysis of alkaline hydrogen oxidation. The details on the formation of a world-class nickel-based HOR catalyst Ni3-MoOx/C-500 are reported via an interfacial reconstruction triggered by passive oxidation upon air exposure. Interfacial reconstruction, initiated with various Ni-Mo metal ratios and annealing temperature, can fine-tune the Ni-Mo interface with an increased work function and a reduced d-band center. The optimized Ni3-MoOx/C exhibits a record high mass activity of 102.8 mA mgNi -1, a top-level exchange current density of 76.5 µA cmNi -2, and exceptional resistance to CO poisoning at 1000 ppm CO for hours. The catalyzed alkaline exchange membrane fuel cell exhibits a maximum power output of 600 mW cm-2 and excellent stability, ranking it as one of the most active non-precious metals HOR catalysts to date.

15.
Water Res ; 260: 121911, 2024 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-38875859

RESUMO

At present, nitrogen (N) leaching from bioretention systems (BRSs) has become a key issue, imposing constraints on their application, a consequence of N dynamics of both inflow and legacy N at different time scales. In this study, the distinct sources (IL: immediate leaching, FL: fast leaching, SL: slow leaching) and the principal transformation processes of different N species (i.e., NH4+, NO3- and DON) leaching originating from inflow and legacy of BRSs were firstly unveiled by various 15N species labeling (i.e., 15N-NH4+, 15N-NO3- and 15N-DON). Results indicate that: NH4+ leaching was primarily caused by FL from influent organic N and SL from influent NH4+, with mineralization being the main transformation process influencing NH4+ leaching; NO3- leaching primarily originated from SL, with the major proportion attributed to the influent organic N in SL, autotrophic and heterotrophic nitrification were the main influencing factors; DON leaching primarily originated from SL, with similar proportions coming from influent organic N, NH4+, and NO3-, inorganic N assimilation was the principal transformation process affecting DON leaching. This study provides an effective framework for apportioning the leaching sources of different N species, providing valuable insights for the implementation of both inflow and legacy N leaching control measures.

16.
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
17.
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.

18.
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.

19.
IUCrJ ; 11(Pt 4): 587-601, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38904547

RESUMO

The success of experimental phasing in macromolecular crystallography relies primarily on the accurate locations of heavy atoms bound to the target crystal. To improve the process of substructure determination, a modified phase-retrieval algorithm built on the framework of the relaxed alternating averaged reflection (RAAR) algorithm has been developed. Importantly, the proposed algorithm features a combination of the π-half phase perturbation for weak reflections and enforces the direct-method-based tangent formula for strong reflections in reciprocal space. The proposed algorithm is extensively demonstrated on a total of 100 single-wavelength anomalous diffraction (SAD) experimental datasets, comprising both protein and nucleic acid structures of different qualities. Compared with the standard RAAR algorithm, the modified phase-retrieval algorithm exhibits significantly improved effectiveness and accuracy in SAD substructure determination, highlighting the importance of additional constraints for algorithmic performance. Furthermore, the proposed algorithm can be performed without human intervention under most conditions owing to the self-adaptive property of the input parameters, thus making it convenient to be integrated into the structural determination pipeline. In conjunction with the IPCAS software suite, we demonstrated experimentally that automatic de novo structure determination is possible on the basis of our proposed algorithm.

20.
IUCrJ ; 11(Pt 4): 602-619, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38904548

RESUMO

Ultra-intense, ultra-fast X-ray free-electron lasers (XFELs) enable the imaging of single protein molecules under ambient temperature and pressure. A crucial aspect of structure reconstruction involves determining the relative orientations of each diffraction pattern and recovering the missing phase information. In this paper, we introduce a predicted model-aided algorithm for orientation determination and phase retrieval, which has been tested on various simulated datasets and has shown significant improvements in the success rate, accuracy and efficiency of XFEL data reconstruction.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA