Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 105
Filtrar
1.
Arch Microbiol ; 206(9): 390, 2024 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-39222088

RESUMEN

Essential amino acid, tryptophan which intake from food plays a critical role in numerous metabolic functions, exhibiting extensive biological functions and applications. Tryptophan is beneficial for the food sector by enhancing nutritional content and promoting the development of functional foods. A putative gene encoding tryptophan synthase was the first identified in Sphingobacterium soilsilvae Em02, a cellulosic bacterium making it inherently more environmentally friendly. The gene was cloned and expressed in exogenous host Escherichia coli, to elucidate its function. The recombinant tryptophan synthase with a molecular weight 42 KDa was expressed in soluble component. The enzymatic activity to tryptophan synthase in vivo was assessed using indole and L-serine and purified tryptophan synthase. The optimum enzymatic activity for tryptophan synthase was recorded at 50 ºC and pH 7.0, which was improved in the presence of metal ions Mg2+, Sr2+ and Mn2+, whereas Cu2+, Zn2+ and Co2+ proved to be inhibitory. Using site-directed mutagenesis, the consensus pattern HK-S-[GGGSN]-E-S in the tryptophan synthase was demonstrated with K100Q, S202A, G246A, E361A and S385A as the active sites. Tryptophan synthase has been demonstrated to possess the defining characteristics of the ß-subunits. The tryptophan synthase may eventually be useful for tryptophan production on a larger scale. Its diverse applications highlight the potential for improving both the quality and health benefits of food products, making it an essential component in advancing food science and technology.


Asunto(s)
Escherichia coli , Mutagénesis Sitio-Dirigida , Triptófano Sintasa , Triptófano , Triptófano Sintasa/metabolismo , Triptófano Sintasa/genética , Triptófano Sintasa/química , Triptófano/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/química , Sphingomonadaceae/enzimología , Sphingomonadaceae/genética , Sphingomonadaceae/metabolismo , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/química , Dominio Catalítico , Clonación Molecular , Concentración de Iones de Hidrógeno , Indoles/metabolismo , Catálisis , Serina/metabolismo
2.
Open Med (Wars) ; 19(1): 20241021, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-39247441

RESUMEN

Background: Emergence agitation (EA) is a behavioural disturbance encountered during the recovery phase of patients following general anaesthesia. It is characterised by restlessness, involuntary limb movements, and drainage tube withdrawal and may significantly harm patients and medical staff. The mechanism of EA has not been fully understood and is still a challenging subject for researchers. Methods: We extracted relevant publications published between 1 January 2001 and 31 December 2023 on the Web of Science Core Collection platform. VOSviewer software was utilised to analyse the retrieved literature and predict the development trends and hotspots in the field. Results: The results show that the number of publications grew annually, with China contributing the most, followed by the United States and South Korea. The co-occurrence of keywords "children," "propofol," "risk factors" are current research hotspots. Owing to its self-limiting and short-duration characteristics, EA lacks standardised clinical time guidelines and objective assessment tools, which may be the focus of future research in this field. Conclusions: Understanding the research hotspots and the latest progress in this field, this study will help to continuously improve the clinical understanding and management of EA, and help to timely identify environmental risk factors for EA in clinical practice.

3.
Adv Sci (Weinh) ; : e2405945, 2024 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-39229956

RESUMEN

Realizing spin transport between heavy metal and two-dimensional (2D) magnetic materials at high Curie temperature (TC) is crucial to advanced spintronic information storage technology. Here, environmentally stable 2D nonlayered Fe3O4 nanosheets are successfully synthesized using a reproducible process and found that they exhibit vortex magnetic domains at room temperature. A Verwey phase transition temperature (TV) of ≈110 K is identified for ≈3 nm thick nanosheet through Raman characterization and spin Hall device measurement of the Pt/Fe3O4 bilayer. The anisotropic magnetoresistance ratio decreases near TV, while both the spin Hall magnetoresistance ratio and spin mixing conductance (Gr) increase at TV. As the temperature approaches 112 K, the anomalous Hall effect ratio tends to become zero. The maximum Gr reaches ≈5 × 1015 Ω-1m-2 due to the clean and flat interface between Pt and 2D nanosheet. The observed spin transport behavior in Pt/Fe3O4 spin Hall devices indicates that 2D Fe3O4 nanosheets possess potential for high-power micro spintronic storage devices applications.

4.
ISME J ; 18(1)2024 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-39129674

RESUMEN

Understanding the ancestral transition from anaerobic to aerobic lifestyles is essential for comprehending life's early evolution. However, the biological adaptations occurring during this crucial transition remain largely unexplored. Thiamine is an important cofactor involved in central carbon metabolism and aerobic respiration. Here, we explored the phylogenetic and global distribution of thiamine-auxotrophic and thiamine-prototrophic bacteria based on the thiamine biosynthetic pathway in 154 838 bacterial genomes. We observed strong coincidences of the origin of thiamine-synthetic bacteria with the "Great Oxygenation Event," indicating that thiamine biosynthesis in bacteria emerged as an adaptation to aerobic respiration. Furthermore, we demonstrated that thiamine-mediated metabolic interactions are fundamental factors influencing the assembly and diversity of bacterial communities by a global survey across 4245 soil samples. Through our newly established stable isotope probing-metabolic modeling method, we uncovered the active utilization of thiamine-mediated metabolic interactions by bacterial communities in response to changing environments, thus revealing an environmental adaptation strategy employed by bacteria at the community level. Our study demonstrates the widespread thiamine-mediated metabolic interactions in bacterial communities and their crucial roles in setting the stage for an evolutionary transition from anaerobic to aerobic lifestyles and subsequent environmental adaptation. These findings provide new insights into early bacterial evolution and their subsequent growth and adaptations to environments.


Asunto(s)
Bacterias , Filogenia , Microbiología del Suelo , Tiamina , Tiamina/biosíntesis , Tiamina/metabolismo , Bacterias/metabolismo , Bacterias/genética , Bacterias/clasificación , Adaptación Fisiológica , Aerobiosis , Vías Biosintéticas , Genoma Bacteriano , Anaerobiosis
5.
J Agric Food Chem ; 72(34): 18840-18850, 2024 Aug 28.
Artículo en Inglés | MEDLINE | ID: mdl-39140307

RESUMEN

Cyromazine, a triazine insecticide, raises food safety concerns due to residues in vegetables like cowpeas. Microbial metabolism is key for pesticide elimination, but bacteria efficient in cyromazine degradation are limited, with uncharacterized enzymes. This study isolated a highly efficient cyromazine-degrading bacterium, Mycobacterium sp. M15, from a cowpea field. M15 utilized cyromazine as the sole carbon source for its growth and completely degraded 0.5 mM cyromazine within 24 h. The degradation pathway involved hydrolyzing cyromazine to N-cyclopropylammeline and further to N-cyclopropylammelide, with amino groups removed sequentially. The cyclopropylamine group in N-cyclopropionamide continued to hydrolyze to cyanuric acid. A protein, CriA, identified as an aminohydrolase in M15, degraded cyromazine to N-cyclopropylammeline. Using CriA reduced cyromazine residues on cowpea surfaces and completely degraded them in immersion solutions. These findings offer insights into cyromazine's microbial degradation mechanism and highlight the potential of cyromazine-degrading enzymes in enhancing food safety.


Asunto(s)
Proteínas Bacterianas , Biodegradación Ambiental , Mycobacterium , Triazinas , Vigna , Triazinas/metabolismo , Triazinas/química , Vigna/metabolismo , Vigna/química , Mycobacterium/metabolismo , Mycobacterium/enzimología , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/química , Insecticidas/metabolismo , Insecticidas/química
6.
Arch Gynecol Obstet ; 310(3): 1749-1755, 2024 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-39143334

RESUMEN

PURPOSE: To explore the effectiveness of sling surgery followed by pelvic floor muscle exercises (PFME) or PFME alone for moderate stress urinary incontinence (SUI) in women and its influencing factors. METHODS: This is a prospective observational cohort study investigating whether sling surgery or PFME is preferred for pre-menopause women with moderate uncomplicated SUI. Those who received PFME alone or sling surgery were divided to PT or TVT group, respectively. The primary outcome was objective cure at 12 months. The secondary outcomes included Incontinence Impact Questionnaire-Short Form (IIQ-7) scores and PFME adherence. RESULTS: The study sample comprised 130 and 74 patients in the PT and TVT groups, respectively. There was 38.2% of patients adhered to PFME twice weekly or more often, and the compliance varied by education level. At 12 months, the objective cure rate was significantly higher in the TVT versus PT group (75.7% vs 47.7%; adjusted OR = 4.27; 95% CI, 2.05-8.87; P < 0.001). In addition, the mean reduction in IIQ-7 scores was greater in the TVT group (16.2 vs 10.0; adjusted OR = 3.38; 95% CI, 1.93-4.82; P < 0.001). However, among patients with lower education or those without adherence to PFME at 12 months, the TVT was also favorized, and the discrepancy in cure rates was greater between the two groups. CONCLUSION: Sling procedures followed by PFME demonstrate greater efficacy versus physiotherapy alone for moderate female SUI management. Continued adherence to PFME was important, even for patients undergoing sling procedures. Educational factors influenced patient PFME adherence and the advantage conferred by sling procedures.


Asunto(s)
Terapia por Ejercicio , Diafragma Pélvico , Cabestrillo Suburetral , Incontinencia Urinaria de Esfuerzo , Humanos , Femenino , Incontinencia Urinaria de Esfuerzo/cirugía , Incontinencia Urinaria de Esfuerzo/terapia , Estudios Prospectivos , Terapia por Ejercicio/métodos , Diafragma Pélvico/fisiopatología , Adulto , Persona de Mediana Edad , Premenopausia , Cooperación del Paciente , Resultado del Tratamiento , Encuestas y Cuestionarios
7.
JCI Insight ; 2024 Aug 20.
Artículo en Inglés | MEDLINE | ID: mdl-39163137

RESUMEN

Palatine tonsils are the only air-contacted lymphoid organs that constantly engage in crosstalk with commensal microorganisms and serve as the first handling sites against microbial antigens. While tonsil inflammations have been implicated in various autoimmune diseases, including rheumatoid arthritis (RA), the precise role of tonsillar microbiota in autoimmune pathogenesis remains inadequately characterized. In this study, we conducted a profiling of the tonsillar microbiota and identified a notable dysbiosis in RA patients, particularly within the Streptococcus genus. Specifically, RA patients exhibited an enrichment of pathogenic Streptococcus species, including S. pyogenes, S. dysgalactiae, and S. agalactiae. Colonization with these bacteria significantly exacerbated arthritis severity and increased autoimmune responses in collagen-induced arthritis (CIA). Furthermore, immunization with peptides derived from these pathogenic Streptococcus species directly induced experimental arthritis. Conversely, RA patients demonstrated a marked deficiency in commensal Streptococcus members, notably S. salivarius. Treatment of CIA mice with S. salivarius attenuated the progression of arthritis and downregulated autoimmune responses. These findings highlight a functional link between tonsillar microbiota and RA, shedding light on their contribution to autoimmunity.

8.
J Diabetes Investig ; 2024 Aug 22.
Artículo en Inglés | MEDLINE | ID: mdl-39171608

RESUMEN

AIMS: To investigate the efficacy of the integrated data platform of cloud hospital combined with dietary management for adults with type 2 diabetes. MATERIALS AND METHODS: We conducted a randomized controlled clinical trial. One hundred eighty patients with type 2 diabetes were randomly allocated into a control group (Group A) and an experimental group (Group B). Routine standard diabetes care was applied to the patients in Group A. The integrated data platform with dietary management was applied to Group B. Individualized diabetes education videos were sent to the patients through the platform. The primary endpoint was the change in HbA1c and change in body weight from baseline to Week 12 during the follow-up. RESULTS: At Week 12, HbA1c was 7.4 ± 0.7%, 6.9 ± 0.9% in Groups A and B, P < 0.01. The rate of fasting blood glucose <7 mmol/L, and glycosylated hemoglobin <7% was higher in Group B than in Group A. At Week 12, there was a significant weight loss and body mass index decrease in the overweight or obese patients of the experimental group. Those overweight or obese patients in the experimental group utilizing the appetite suppressant semaglutide achieved the most significant weight loss, with a 13.4% reduction after 12 weeks. CONCLUSIONS: The integrated data platform combined with personalized diabetes education video delivery was verified to be a more effective management mode for diabetes. For overweight or obese adults with diabetes, the use of semaglutide in conjunction with dietary management and the integrated data platform led to greater weight loss.

9.
Sci Bull (Beijing) ; 2024 Aug 06.
Artículo en Inglés | MEDLINE | ID: mdl-39153908

RESUMEN

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease triggered by antigenic peptides with environmental and genetic risk factors. It has been shown that antigen-specific targeting could be a promising therapeutical strategy for RA by restoring immune tolerance to self-antigens without compromising normal immunity. Citrullination of antigens enhances antigenic properties and induces autoimmune responses. Here, we showed that citrullinated antigenic (citAg) vaccine ameliorated collagen-induced arthritis (CIA) with decreased T-helper 1 (Th1) and Th17 cells, downregulated proinflammatory cytokines including interlukin-6 and tumor necrosis factor-α, and inhibited antigen recall responses. B cell receptor (BCR) sequencing further revealed that citAg vaccine could dampen the dysregulated V(D)J recombination, restoring the immune repertoire. Taken together, the results demonstrated that citAg vaccine might have a therapeutic effect on RA.

10.
Chin J Integr Med ; 2024 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-38990478

RESUMEN

Atrial fibrillation (AF) is the most common arrhythmia in clinical practice. It has a high prevalence and poor prognosis. The application of antiarrhythmic drugs and even surgery cannot completely treat the disease, and there are many sequelae. AF can be classified into the category of "palpitation" in Chinese medicine according to its symptoms. Acupuncture has a significant effect on AF. The authors find that an important mechanism of acupuncture in AF treatment is to regulate the cardiac vagus nerve. Therefore, this article intends to review the distribution and function of vagus nerve in the heart, the application and the regulatroy effect for the treatment of AF.

11.
Ann Rheum Dis ; 2024 Jul 31.
Artículo en Inglés | MEDLINE | ID: mdl-39084885

RESUMEN

OBJECTIVES: Viruses have been considered as important participants in the development of rheumatoid arthritis (RA). However, the profile of enteric virome and its role in RA remains elusive. This study aimed to investigate the atlas and involvement of virome in RA pathogenesis. METHODS: Faecal samples from 30 pairs of RA and healthy siblings that minimise genetic interferences were collected for metagenomic sequencing. The α and ß diversity of the virome and the virome-bacteriome interaction were analysed. The differential bacteriophages were identified, and their correlations with clinical and immunological features of RA were analysed. The potential involvement of these differential bacteriophages in RA pathogenesis was further investigated by auxiliary metabolic gene annotation and molecular mimicry study. The responses of CD4+ T cells and B cells to the mimotopes derived from the differential bacteriophages were systemically studied. RESULTS: The composition of the enteric bacteriophageome was distorted in RA. The differentially presented bacteriophages correlated with the immunological features of RA, including anti-CCP autoantibody and HLA-DR shared epitope. Intriguingly, the glycerolipid and purine metabolic genes were highly active in the bacteriophages from RA. Moreover, peptides of RA-enriched phages, in particular Prevotella phage and Oscillibacter phage could provoke the autoimmune responses in CD4+ T cells and plasma cells via molecular mimicry of the disease-associated autoantigen epitopes, especially those of Bip. CONCLUSIONS: This study provides new insights into enteric bacteriophageome in RA development. In particular, the aberrant bacteriophages demonstrated autoimmunity-provoking potential that would promote the occurrence of the disease.

12.
Dent Mater J ; 43(4): 597-608, 2024 Jul 31.
Artículo en Inglés | MEDLINE | ID: mdl-38960668

RESUMEN

The glass infiltration technique was employed for surface modification of zirconia implants in this study. The prepared glass-infiltrated zirconia with low infiltrating temperature showed excellent mechanical properties and enough infiltrating layer. The zirconia substrate was pre-sintered at 1,200°C and the glass infiltration depth reached 400 µm after infiltrating at 1,200°C for 10 h. The infiltrating glass has good wetting ability, thermal expansion match and good chemical compatibility with the zirconia substrate. Indentation fracture toughness and flexural strength of the dense sintered glass-infiltrated zirconia composite are respectively 5.37±0.45 MPa•m1/2 and 841.03±89.31 MPa. Its elasticity modulus is 163.99±7.6 GPa and has about 500 µm infiltrating layer. The glass-infiltrated zirconia can be acid etched to a medium roughness (1.29±0.09 µm) with a flexural strength of 823.65±87.46 MPa, which promotes cell proliferation and has potential for dental implants.


Asunto(s)
Implantes Dentales , Resistencia Flexional , Vidrio , Ensayo de Materiales , Propiedades de Superficie , Circonio , Circonio/química , Vidrio/química , Módulo de Elasticidad , Temperatura , Materiales Dentales/química , Grabado Ácido Dental
14.
Langmuir ; 40(27): 13773-13783, 2024 Jul 09.
Artículo en Inglés | MEDLINE | ID: mdl-38920266

RESUMEN

Cartilage defects in large joints are a common occurrence in numerous degenerative diseases, especially in osteoarthritis. The hydrogel-on-metal composite has emerged as a potential candidate material, as hydrogels, to some extent, replicate the composition of human articular cartilage consisting of collagen fibers and proteoglycans. However, achieving tough bonding between the hydrogel and titanium alloy remains a significant challenge due to the swelling of the hydrogel in a liquid medium. This swelling results in reduced interfacial toughness between the hydrogel and titanium alloy, limiting its potential clinical applications. Herein, our approach aimed to achieve durable bonding between a hydrogel and a titanium alloy composite in a swollen state by modifying the surface texture of the titanium alloy. Various textures, including circular and triangular patterns, with dimple densities ranging from 10 to 40%, were created on the surface of the titanium alloy. Subsequently, poly(vinyl alcohol) (PVA) hydrogel was deposited onto the textured titanium alloy using a casting-drying method. Our findings revealed that PVA hydrogel on the textured titanium alloy with a 30% texture density exhibited the highest interfacial toughness in the swollen state, measuring at 1300 J m-2 after reaching equilibrium swelling in deionized water, which is a more than 2-fold increase compared to the hydrogel on a smooth substrate. Furthermore, we conducted an analysis of the morphologies of the detached hydrogel from the textured titanium alloy after various swelling durations. The results indicated that interfacial toughness could be enhanced through mechanical interlocking, facilitated by the expanded volume of the hydrogel protrusions as the swelling time increased. Collectively, our study demonstrates the feasibility of achieving tough bonding between a hydrogel and a metal substrate in a liquid environment. This research opens up promising avenues for designing soft/hard heterogeneous materials with strong adhesive properties.

15.
Artículo en Inglés | MEDLINE | ID: mdl-38781519

RESUMEN

OBJECTIVES: The routine biomarkers for rheumatoid arthritis (RA), including anticyclic citrullinated peptide antibody (anti-CCP), rheumatoid factor (RF), immunoglobulin M (IgM), erythrocyte sedimentation rate (ESR), and C-reaction protein (CRP) have limited sensitivity and specificity. Scavenger receptor-A (SR-A) is a novel RA biomarker identified by our group recently, especially for seronegative RA. Here, we performed a large-scale multicentre study to further assess the diagnostic value of SR-A in combination with other biomarkers for RA. METHODS: The performance of SR-A in combination with other biomarkers for RA diagnosis was first revealed by a pilot study, and was further elucidated by a large-scale multicentre study. A total of 1129 individuals from 3 cohorts were recruited in the study, including RA patients, healthy controls, and patients with other common rheumatic diseases. Diagnostic properties were evaluated by the covariate-adjusted receiver-operating characteristic (AROC) curve, sensitivity, specificity and clinical association, respectively. RESULTS: Large-scale multicentre analysis showed that SR-A and anti-CCP dual combination was the optimal method for RA diagnosis, increasing the sensitivity of anti-CCP by 13% (87% vs 74%) while maintaining a specificity of 90%. In early RA patients, SR-A and anti-CCP dual combination also showed promising diagnostic value, increasing the sensitivity of anti-CCP by 7% (79% vs 72%) while maintaining a specificity of 94%. Moreover, SR-A and anti-CCP dual combination was correlated with ESR, IgM, and autoantibodies of RA patients, further revealing its clinical significance. CONCLUSION: SR-A and anti-CCP dual combination could potentially improve early diagnosis of RA, thus improving the prognosis and reducing mortality.

16.
J Hazard Mater ; 470: 134175, 2024 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-38574662

RESUMEN

Emerging organic photoelectrochemical transistors (OPECTs) with inherent amplification capabilities, good biocompatibility and even self-powered operation have emerged as a promising detection tool, however, they are still not widely studied for pollutant detection. In this paper, a novel OPECT dual-mode aptasensor was constructed for the ultrasensitive detection of di(2-ethylhexyl) phthalate (DEHP). MXene/In2S3/In2O3 Z-scheme heterojunction was used as a light fuel for ion modulation in sensitive gated OPECT biosensing. A transistor system based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) converted biological events associated with photosensitive gate achieving nearly a thousand-fold higher current gain at zero bias voltage. This work quantified the target DEHP by aptamer-specific induction of CRISPR-Cas13a trans-cutting activity with target-dependent rolling circle amplification as the signal amplification unit, and incorporated the signal changes strategy of biocatalytic precipitation and TMB color development. Combining OPECT with the auxiliary validation of colorimetry (CM), high sensitivity and accurate detection of DEHP were achieved with a linear range of 0.1 pM to 200 pM and a minimum detection limit of 0.02 pM. This study not only provides a new method for the detection of DEHP, but also offers a promising prospect for the gating and application of the unique OPECT.


Asunto(s)
Técnicas Biosensibles , Dietilhexil Ftalato , Técnicas Electroquímicas , Transistores Electrónicos , Aptámeros de Nucleótidos/química , Técnicas Biosensibles/métodos , Sistemas CRISPR-Cas , Dietilhexil Ftalato/química , Dietilhexil Ftalato/análisis , Técnicas Electroquímicas/instrumentación , Técnicas Electroquímicas/métodos , Límite de Detección , Técnicas de Amplificación de Ácido Nucleico , Poliestirenos/química , Tiofenos , Contaminantes Químicos del Agua/análisis
17.
Int J Biol Macromol ; 268(Pt 1): 131627, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38636752

RESUMEN

Nanoparticles-loaded bio-based polymers have emerged as a sustainable substitute to traditional oil-based packaging materials, addressing the challenges of limited recyclability and significant environmental impact. However, the functionality and efficiency of nanoparticles have a significant impact on the application of bio-based composite films. Herein, graphitic carbon nitride (g-C3N4) and titanium dioxide (TiO2) coupled photocatalyst (g-C3N4-TiO2) was prepared by one-step calcination and introduced into chitosan (CS) and polyvinyl alcohol (PVA) solution to fabricate g-C3N4-TiO2/CS/PVA green renewable composite film via solution casting method. The results demonstrated the successful preparation of a Z-scheme heterojunction g-C3N4-TiO2 with exceptional photocatalytic activity. Furthermore, the incorporation of heterojunction enhanced mechanical properties, water barrier, and ultraviolet (UV) resistance properties of the fresh-keeping film. The g-C3N4-TiO2/CS/PVA composite film exhibited superior photocatalytic antibacterial preservation efficacy on strawberries under LED light, with a prolonged preservation time of up to 120 h, when compared to other films such as polyethylene (PE), CS/PVA, g-C3N4/CS/PVA, and TiO2/CS/PVA. In addition, the composite film has good recyclability and renewability. This work is expected to have great potential for low-cost fruit preservation and sustainable packaging, which also contributes to environmental protection.


Asunto(s)
Quitosano , Embalaje de Alimentos , Grafito , Alcohol Polivinílico , Titanio , Titanio/química , Quitosano/química , Alcohol Polivinílico/química , Embalaje de Alimentos/métodos , Grafito/química , Frutas/química , Catálisis , Compuestos de Nitrógeno/química , Antibacterianos/química , Antibacterianos/farmacología
18.
Beijing Da Xue Xue Bao Yi Xue Ban ; 56(2): 345-351, 2024 Apr 18.
Artículo en Chino | MEDLINE | ID: mdl-38595256

RESUMEN

OBJECTIVE: To analyze the influence of forming direction on the surface characteristics, elastic modulus, bending strength and fracture toughness of printed parts and the relationship between forming direction and force direction, and to provide scientific basis and guidance for the clinical application of oral denture base resin materials. METHODS: The 3D printing technology was used to print denture base resin samples. The shape and size of the samples referred to the current standard for testing conventional denture base materials. The samples used for physical performance testing were cylindrical (with a diameter of 15 mm and a thickness of 1 mm) and printed at different angles along the Z axis (0°, 45°, 90°). Scanning electron microscope was used to observe the microscopic topography of the different samples. The color stability of different samples was observed by color stabilizer. The surface roughness of the samples was analyzed by using surface roughness tester. The Vickers hardness was measured to analyze the hardness of the samples. The samples used for mechanical performance testing were rectangular (elastic modulus and bending strength: A length of 64 mm, a width of 10 mm, and a height of 3.3 mm; fracture toughness: A length of 39 mm, a width of 8 mm, and a height of 4 mm), divided into two groups: W group and H group. The W group was printed from the bottom up along the Z axis with the length × width as the bottom surface parallel to the X, Y axis plane, while the H group printed from the bottom up along the Z axis with the length × height as the bottom surface parallel to the X, Y axis plane. The forming angles of both groups were equally divided into 0°, 45°, and 90°. The elastic modulus, bending strength and fracture toughness of different samples were studied through universal mechanical testing machine. SPSS 22.0 software was used for statistical analysis. RESULTS: The microscopic topography and roughness of different samples were closely related to the printing direction, with significant differences between the 0°, 45°, and 90° specimens. The 0° specimens had the smoothest surface (roughness < 1 µm). The surface of the 45° specimen was the roughest (roughness>3 µm). The microhardness of the 0° sample was the best [(196.13±0.20) MPa], with a significant difference compared with the 90° sample [(186.62±4.81) MPa, P < 0.05]. The mechanical properties of different samples were also closely related to the printing direction. The elastic modulus, bending strength, and fracture toughness of the 45° samples in the W group were the highest compared with the other groups. The results of elastic modulus showed that in the H group, the 45° specimens had the highest elastic mo-dulus, which was significantly different from the 0° and 90° specimens (P < 0.05). The elastic modulus of 0° and 45° specimens in the W group were higher than those in 90° specimens (P < 0.05). The bending strength results showed that there was no significant difference between the specimens from dif-ferent angles in the H group. The bending strength of the 90° specimens in the W group was the smallest, and there was a significant difference between 90° and the 0° and 45° specimens (P < 0.05); And the bendind strength of the 0° and 45° specimens in the W group was significantly higher than that of the 0° and 45° specimens in the H group (P < 0.05). The fracture toughness results showed that the fracture toughness of the H group specimens was lower than 1.9 MPa m1/2, which was specified in the denture base standard. The 45° samples in the W group were the highest, with significant differences compared with the 0° and 90° samples (P < 0.05). And the 90° samples of the W group specimens were lower than 1.9 MPa m1/2. And the fracture toughness of the 45° specimen in the W group was significantly higher than that of all the specimens in the H group (P < 0.05). CONCLUSION: The 0° samples had relatively better physical properties. The 45° samples had the best mechanical properties. But the fracture toughness of specimens (H group and 90° samples of W group) did not yet meet clinical requirements. That indicated that the characteristics of the 3D printing denture base resin were affected by the printing direction. Only when the performance of the printed samples in all directions met the minimum requirements of the standard, they could be used in clinical practice.


Asunto(s)
Impresión Tridimensional , Prostodoncia , Ensayo de Materiales , Propiedades de Superficie , Resistencia Flexional , Bases para Dentadura
19.
ACS Appl Mater Interfaces ; 16(15): 19764-19770, 2024 Apr 17.
Artículo en Inglés | MEDLINE | ID: mdl-38577833

RESUMEN

Two-dimensional van der Waals (2D vdW) materials are widely used in spin-orbit torque (SOT) devices. Recent studies have demonstrated the low crystal symmetry and large spin Hall conductivity of 2D vdW ZrSe3, indicating its potential applications in low-power SOT devices. Here, we study the interfacial contribution of SOTs and current-induced magnetization switching in the ZrSe3/Py (Ni80Fe20) and ZrSe3/Cu/Py heterostructures. SOT efficiencies of samples are detected by the spin-torque ferromagnetic resonance (ST-FMR), and out-of-plane damping-like torque (τB) is observed. The ratio between τB and the field-like torque (τA) decreases from 0.175 to 0.138 when inserting 1 nm Cu at the interface and then drops to 0.001 when the thickness of Cu intercalation is 2 nm, indicating that Cu intercalation inhibits the τB component of SOT. Moreover, the SOT efficiency is increased from 3.05 to 5.21, which may be attributed to the Cu intercalation being beneficial to improve the interface between Py and ZrSe3. Theoretical calculation has shown that the Cu spacer can change the conductivity of ZrSe3 from semiconductor to conductor, thereby decreasing the Schottky barrier and increasing the transmission efficiency of the spin current. Furthermore, magneto-optical Kerr effect (MOKE) microscopy is employed to verify the current-driven magnetization switching in these structures. In comparison to the ZrSe3/Py bilayer, the critical current density of ZrSe3/Cu/Py is reduced when inserting 1 nm Cu, demonstrating the higher SOT efficiency and lower power consumption in ZrSe3/Cu/Py structures.

20.
Artif Intell Med ; 150: 102813, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38553155

RESUMEN

Named entity recognition (NER) is an important task for the natural language processing of biomedical text. Currently, most NER studies standardized biomedical text, but NER for unstandardized biomedical text draws less attention from researchers. Named entities in online biomedical text exist with errors and polymorphisms, which negatively impact NER models' performance and impede support from knowledge representation methods. In this paper, we propose a neural network method that can effectively recognize entities in unstandardized online medical/health text. We introduce a new pre-training scheme that uses large-scale online question-answering pairs to enhance transformers' model capacity on online biomedical text. Moreover, we supply models with knowledge representations from a knowledge base called multi-channel knowledge labels, and this method overcomes the restriction from languages, like Chinese, that require word segmentation tools to represent knowledge. Our model outperforms other baseline methods significantly in experiments on a dataset for Chinese online medical entity recognition and achieves state-of-the-art results.


Asunto(s)
Procesamiento de Lenguaje Natural , Redes Neurales de la Computación
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA