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1.
Phys Chem Chem Phys ; 26(25): 17707-17719, 2024 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-38869465

RESUMEN

A high-precision global potential energy surface (PES) of the Li3 system is constructed based on high-level ab initio calculations, and the root-mean-square error is 5.54 cm-1. The short-range of the PES is fitted by the fundamental invariant neural network (FI-NN) method, while the long-range uses a function with an accurate asymptotic potential energy form, and the two regions are connected by a switching function. Based on the new PES, the statistical quantum-mechanical (SQM) and the time-dependent wave packet (TDWP) methods are used to study the dynamics of 7Li + 6Li2 (v = 0, j = 0) → 6Li7Li + 6Li reactions in the low collision energy region (10-11 to 10-3 cm-1) and the high collision energy region (8 to 800 cm-1), respectively. In the high collision energy region, the calculation results of the SQM method and the TDWP method are inconsistent, indicating that the reaction dynamics does not follow the statistical behavior in the high collision energy region. In addition, we found that the Coriolis coupling effect plays an important role in this reaction. The symmetric forward-backward scattering in the total DCS indicates that the reaction follows the complex-forming reaction mechanism.

2.
J Phys Chem A ; 128(26): 5115-5127, 2024 Jul 04.
Artículo en Inglés | MEDLINE | ID: mdl-38889710

RESUMEN

The ultracold reaction offers a unique opportunity to elucidate the intricate microscopic mechanism of chemical reactions, and the Na2Li system serves as a pivotal reaction system in the investigation of ultracold reactions. In this work, a high-precision potential energy surface (PES) of the Na2Li system is constructed based on high-level ab initio energy points and the neural network (NN) method, and a proper asymptotic functional form is adopted for the long-range interaction, which is suitable for the study of cold or ultracold collisions. Based on the new NN PES, the dynamics of the Li + Na2 (v = 0, j = 0) → Na + NaLi reaction are studied in the collision energy range of 10-7 to 80 cm-1. In the high collision energy range of 8 to 80 cm-1, the dynamics of the reaction is studied using the time-dependent wave packet method and the statistical quantum mechanical (SQM) method. Comparing the results of the two methods, it is found that the SQM method provides a rough description of the product ro-vibrational state distribution but overestimates the integral cross-section values. With the decrease of collision energy, the reaction differential cross section gradually changes from forward-backward symmetric scattering to predominant forward scattering. In the low collision energy range from 10-7 to 8 cm-1, the SQM method is used to study the reaction dynamics, and the rate constant in the Wigner threshold region is estimated to be 2.87 × 10-10 cm3/s.

3.
BMC Nurs ; 23(1): 420, 2024 Jun 21.
Artículo en Inglés | MEDLINE | ID: mdl-38907353

RESUMEN

BACKGROUND: The lack of professional identity can impede the transition from nursing students to qualified nurses and exacerbate the shortage of health care professionals. Personality is important to resilience-building and professional identity development in nursing students. However, the associations among personality, resilience, and professional identity are less explored. The study aims to identify latent subtypes of personality, to evaluate the mediating role of resilience between personality and professional identity in nursing students, and to provide practical guidance for educators' subsequent interventions with nursing students' professional identity. METHODS: 1397 nursing students were recruited from Be Resilient to Nursing Career (BRNC) between October 2020 and April 2022 by cluster sampling from 4 universities in China. NEO Five-Factor Inventory, 10-item Connor-Davidson Resilience Scale, and Professional Identity Questionnaire for Undergraduate Students were administered. Analyses of latent profiles and mediations were performed. RESULTS: Three latent personality types were identified: Over-sensitivity (35.4%), Ordinary (53.8%), and Flexibility (10.8%). Nursing role model was found to be a significant indicator of personality (Ordinary as ref, Over-sensitivity: OR = 0.73, 95% CI: 0.57-0.93, P = 0.010; Flexibility: OR = 1.85, 95% CI: 1.29-2.65, P = 0.001). The association between personality portraits and professional identity were significantly mediated by resilience (P < 0.05). CONCLUSIONS: There exists heterogeneity in nursing students' personality. Resilience plays a significant role in mediating the relationship between personality and professional identity.

4.
Small ; 19(43): e2303294, 2023 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-37356060

RESUMEN

The uncontrollable growth and uneven nucleation of lithium metal can be addressed by utilizing spatial confinement structures in conjunction with lithiophilic sites. However, their complex fabrication technique and the inhomogeneous dispersion of lithiophilic sites make the application ineffective. In this work, ultra-uniformly dispersed SiOx seeds and defects are produced in situ to achieve the spatially restricted protection within the reduced graphene oxide (rGO) layer. The in situ formed SiOx and defects during annealing double constrain lithium nucleation and growth behaviors thanks to the superlithiophilic characteristic, while both provide the fast Li+ transport channel to utilize the interlayer protection of rGO in limiting lithium dendrite growth. Furthermore, XANES and XPS analyze the SiOx seeds that are dominated by various valence states, and theoretical calculations further verify the control on the nucleation of lithium atoms. Benefiting from the optimum average valence of three for the "control site", the host realizes steady circulation. In asymmetric cells, the host demonstrates excellent coulombic efficiency of 99.1% and stable lifespans over 1250 h at 1 mA cm-2 . When assembled in LiFePO4 full cells, it retains a favorable capacity of 116.2 mA h g-1 after 170 cycles.

5.
Small ; 19(17): e2207167, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36703536

RESUMEN

Because of its high specific capacity, the silicon-graphite composite (SGC) is regarded as a promising anode for new-generation lithium-ion batteries. However, the frequently employed two-section preparation process, including the modification of silicon seed and followed mixture with graphite, cannot ensure the uniform dispersion of silicon in the graphite matrix, resulting in a stress concentration of aggregated silicon domains and cracks in composite electrodes during cycling. Herein, inspired by powder engineering, the two independent sections are integrated to construct multistage stable silicon-graphite hybrid granules (SGHGs) through wet granulation and carbonization. This method assembles silicon nanoparticles (Si NPs) and graphite and improves compatibility between them, addressing the issue of severe stress concentration caused by uncombined residue of Si NPs. The optimal SGHG prepared with 20% pitch content exhibits a highly reversible specific capacity of 560.0 mAh g-1 at a current density of 200 mA g-1 and a considerable stability retention of 86.1% after 1000 cycles at 1 A g-1 . Moreover, as a practical application, the full cell delivers an outstanding capacity retention of 85.7% after 400 cycles at 2 C. The multistage stable structure constructed by simple wet granulation and carbonization provides theoretical guidance for the preparation of commercial SGC anodes.

6.
Macromol Rapid Commun ; 44(12): e2300024, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-37078381

RESUMEN

Natural spider silks with striking performances achieve extensive investigations. Nonetheless, a lack of consensus over the mechanism of the natural spinning hinders the development of artificial spinning methods where the regenerated spider silks generally show poor performances compared with the natural fibers. As is known, the Plateau-Rayleigh instability tends to break solution column into droplets and is considered a main challenge during fiber-spinning. Here in this study, by harnessing the viscoelastic properties of the regenerated spidroin dope solution via organic salt-zinc acetate (ZA), this outcome can be avoided, and dry-spinning of long and mechanically robust regenerated spider silk ribbons can be successfully realized. The as-obtained dry-spun spider silk ribbons show an enhanced modulus up to 14 ± 4 GPa and a toughness of ≈51 ± 9 MJ m-3 after the post-stretching treatment, which is even better than that of the pristine spider silk fibers. This facile and flexible strategy enriches the spinning methodologies which bypass the bottleneck of precisely mimicking the complex natural environment of the glands in spiders, shining a light to the spider-silk-based textile industrial applications.


Asunto(s)
Fibroínas , Arañas , Animales , Seda
7.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 40(5): 928-937, 2023 Oct 25.
Artículo en Zh | MEDLINE | ID: mdl-37879922

RESUMEN

Accurate segmentation of pediatric echocardiograms is a challenging task, because significant heart-size changes with age and faster heart rate lead to more blurred boundaries on cardiac ultrasound images compared with adults. To address these problems, a dual decoder network model combining channel attention and scale attention is proposed in this paper. Firstly, an attention-guided decoder with deep supervision strategy is used to obtain attention maps for the ventricular regions. Then, the generated ventricular attention is fed back to multiple layers of the network through skip connections to adjust the feature weights generated by the encoder and highlight the left and right ventricular areas. Finally, a scale attention module and a channel attention module are utilized to enhance the edge features of the left and right ventricles. The experimental results demonstrate that the proposed method in this paper achieves an average Dice coefficient of 90.63% in acquired bilateral ventricular segmentation dataset, which is better than some conventional and state-of-the-art methods in the field of medical image segmentation. More importantly, the method has a more accurate effect in segmenting the edge of the ventricle. The results of this paper can provide a new solution for pediatric echocardiographic bilateral ventricular segmentation and subsequent auxiliary diagnosis of congenital heart disease.


Asunto(s)
Ecocardiografía , Ventrículos Cardíacos , Adulto , Humanos , Niño , Ventrículos Cardíacos/diagnóstico por imagen , Procesamiento de Imagen Asistido por Computador
8.
Nanotechnology ; 33(39)2022 Jul 04.
Artículo en Inglés | MEDLINE | ID: mdl-35700715

RESUMEN

The conductive skeleton and aligned carbon nanotube array (CNTA) structure can greatly shorten the ion transfer path and promote the charge transfer speed, which makes the CNTA an ideal electrode material for energy storage application. However, poor mechanical stability and low specific capacitance greatly impede its practical utilization. Here, we introduce a promising flexible electrode material based on the natural spider silk protein (SSP) modified CNTA(SSP/CNTA) with improved hydrophilicity and mechanical flexibility. The redox-active Fe3+doped SSP/CNTA flexible solid-state supercapacitor (FSSC) device with superior energy storage performance was assembled in a symmetric 'sandwich-type' structure. The synergetic interaction between Fe3+ions and the SSP are proved to greatly enhance the electrochemical performance especially the long-term cyclic stability. The Fe3+doped SSP/CNTA FSSCs device achieves an ultra-high volumetric capacitance of 4.92 F cm-3at a sweep speed of 1 mV s-1. Meanwhile it exhibited an excellent cycling stability with an increased capacitance by 10% after 10 000 charge-discharge cycles. As a control, a Fe3+doped CNTA composite device without SSP will lose over 74% of the capacitance after 10 000 cycles. The energy storage mechanism analysis confirms the dominated capacitive behavior of the device, which explained a considerable power density and rate performance. Our method thus provides a promising strategy to build up highly-efficient redox-enhanced FSSCs for next generation of wearable and implantable electronics.

9.
Inflammopharmacology ; 30(4): 1445-1458, 2022 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-35451724

RESUMEN

OBJECTIVES: As the main cause of osteoporosis, abnormal activity of osteoclasts could disrupt the balance between bone resorption and formation. Moreover, up-regulation of nuclear factor-kappa ligand (RANKL) expression by chronic inflammation-mediated inflammatory factors might contribute to the differentiation of osteoclast precursor cells. Therefore, an anti-inflammatory agent named yangonin was presented for inhibiting osteoclast and relieving inflammatory osteoporosis through down-regulating inflammatory factors. METHODS: We established a model of macrophage inflammation and then verified the anti-inflammatory effect of yangonin. The inhibitory effect of yangonin on osteoclasts was detected by tartrate-resistant acid phosphatase (TRAP) staining, Western blotting and quantitative real-time PCR (qRT-PCR). Finally, micro-CT, TRAP and hematoxylin-eosin (HE) staining were used to show the effect of yangonin on inflammatory osteoporosis in vivo. RESULTS: Our results suggested that yangonin was able to reduce the secretion of inflammatory factors, down-regulate osteoclast-related genes such as TRAP, RANKL, cathepsin K (CTSK) and nuclear factor-activated T-cell 1 (NFATc1). Furthermore, it was demonstrated that yangonin could suppress the function of inflammatory cytokines in osteoclast differentiation and reporting, wherein NF-κB, AKT and downstream c-Fos/NFATc1 signaling pathways were involved. In an in vivo study, we implied that yangonin has a relieving effect on inflammatory osteoporosis. CONCLUSION: Our research shows that yangonin down-regulates inflammatory factors and inhibits the bone-breaking effect of inflammation through NF-κB, AKT and downstream c-Fos/NFATc1 signaling pathways to achieve the purpose of treating inflammatory osteoporosis.


Asunto(s)
Resorción Ósea , Osteoporosis , Resorción Ósea/tratamiento farmacológico , Diferenciación Celular , Humanos , Inflamación/tratamiento farmacológico , Inflamación/metabolismo , Ligandos , FN-kappa B/metabolismo , Osteoclastos/metabolismo , Osteoporosis/tratamiento farmacológico , Osteoporosis/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Pironas , Ligando RANK/metabolismo
10.
Bull Environ Contam Toxicol ; 109(4): 651-658, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-35908225

RESUMEN

Contaminated soils have caused serious harm to human health and the ecological environment due to the high toxicity of organic and inorganic pollutants, which has attracted extensive attention in recent years. Because of its low cost, simple operation and high efficiency, soil washing technology is widely used to permanently remove various pollutants in contaminated soils and is considered to be the most promising remediation technology. This review summarized the recent developments in the field of soil washing technology and discusses the application of conventional washing agents, advanced emerging washing agents, the recycling of washing effluents and the combination of soil washing and other remediation technologies. Overall, the findings provide a comprehensive understanding of soil washing technology and suggest some potential improvements from a scientific and practical point of view.


Asunto(s)
Restauración y Remediación Ambiental , Metales Pesados , Contaminantes del Suelo , Contaminación Ambiental , Humanos , Metales Pesados/análisis , Suelo , Contaminantes del Suelo/análisis , Tecnología
11.
Zhongguo Dang Dai Er Ke Za Zhi ; 24(11): 1231-1237, 2022 Nov 15.
Artículo en Zh | MEDLINE | ID: mdl-36398549

RESUMEN

OBJECTIVES: To summarize the skeletal muscle magnetic resonance imaging (MRI) features of the lower limbs in common subtypes of muscular dystrophy (MD) and the experience in the application of MRI in the diagnosis of MD. METHODS: A total of 48 children with MD who were diagnosed by genetic testing were enrolled as subjects. The muscle MRI features of the lower limbs were analyzed. Cumulative fatty infiltration score was calculated for each subtype, and the correlation of cumulative fatty infiltration score with clinical indices was analyzed for Duchenne muscular dystrophy (DMD). RESULTS: DMD was characterized by the involvement of the gluteus maximus and the adductor magnus. Becker muscular dystrophy was characterized by the involvement of the vastus lateralis muscle. Limb-girdle muscular dystrophy was characterized by the involvement of the adductor magnus, the vastus intermedius, the vastus medialis, and the vastus lateralis muscle. For DMD, the cumulative fatty infiltration score of the lower limb muscles was significantly correlated with age, course of the disease, muscle strength, and motor function (P<0.05), while it was not significantly correlated with the serum creatine kinase level (P>0.05). CONCLUSIONS: Different subtypes of MD have different MRI manifestations, and MRI may help with the diagnosis and assessment of MD.


Asunto(s)
Distrofia Muscular de Cinturas , Distrofia Muscular de Duchenne , Niño , Humanos , Distrofia Muscular de Duchenne/diagnóstico por imagen , Distrofia Muscular de Cinturas/diagnóstico por imagen , Distrofia Muscular de Cinturas/patología , Músculo Esquelético/diagnóstico por imagen , Imagen por Resonancia Magnética/métodos , Muslo/patología
12.
Langmuir ; 37(15): 4523-4531, 2021 Apr 20.
Artículo en Inglés | MEDLINE | ID: mdl-33822634

RESUMEN

We investigated the selective adsorption and desorption behaviors of charged molecules (calcein, brilliant green, and methylene blue) dissolved in water using polydopamine-modified carbon nanotube (CNT) sponges. Porous CNT sponges (CNTSs) as a scaffold for the selective adsorption and desorption of aqueous molecules were fabricated by using a chemical vapor deposition technique. To improve the hydrophilicity of porous CNTS and to control the adsorption and desorption of aqueous molecules, CNT sidewalls were decorated with a hydrophilic polydopamine layer through noncovalent interactions between CNT sidewalls and polydopamine. After this noncovalent chemical modification, the water contact angle of CNTS was close to 0, and the aqueous solution can rapidly infiltrate the three-dimensional (3D) networks of polydopamine-modified CNTS (Pdop-CNTS). The incorporation of pH-responsive polydopamine in CNTS showed an evident advantage of adsorbing positively charged molecules over a pH range of 10.5-4. In aqueous solutions with pH value of ≤3, Pdop-CNTS selectively adsorbed negatively charged molecules. Aqueous molecules carrying net charges were successfully separated from mixture solutions. Moreover, charged calcein and methylene blue molecules adsorbed on the 3D networks of Pdop-CNTS were selectively desorbed from Pdop-CNTS by tuning the pH value of the desorption solution.

13.
Nanotechnology ; 32(10): 105709, 2021 Mar 05.
Artículo en Inglés | MEDLINE | ID: mdl-33260168

RESUMEN

We investigated the effect of an electric treatment on the wettability of aqueous solution on carbon nanotubes (CNT) and ion transport behaviors in superhydrophobic porous carbon nanotube sponges (CNTS). This electric activation treatment where an electric voltage was applied across highly porous CNT sponge induced an electrowetting effect. This effect significantly reduced interfacial tensions between CNT sidewalls and aqueous liquids. Meanwhile, polar functional groups were also introduced on CNTs. Both electrowetting effect and polar functional groups greatly improved the wettability of aqueous solutions on CNT sidewalls. After the electric treatment, we observed a dramatic increase in the overall rate of ion flow across porous CNT sponges. The formation of solution channels during the electric treatment is responsible for the enhanced ionic transport in porous CNT sponges. The overall rate of ion flow increased with the increases in electric treatment time and voltage. The crucial role of electric treatment parameters in the ion transport provides a new strategy for precisely controlling the ion transport across CNT sponges by tuning electric treatment time or voltage. Importantly, the good wettability of aqueous solution on CNT sidewalls greatly increased the effective surface area of CNT sponges and thus significantly improved the performance of CNTS-based supercapacitors after the electric treatment.

14.
Phys Chem Chem Phys ; 22(37): 21297-21306, 2020 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-32935675

RESUMEN

The glass transition behaviors of thin polymer films on the sidewalls of carbon nanotubes (CNTs) in CNT sponges (CNTSs) were studied. Due to the extremely large surface area of CNTS, the glass transition temperatures (Tg) of thin polystyrene (PS) and poly(methyl methacrylate) (PMMA) films were measured using a routine experimental method, differential scanning calorimetry (DSC). We thus provide a direct Tg comparison between the thin film and the bulk sample using the same DSC technique. For thin polymer films on the CNT sidewalls, free surface and polymer-substrate interfacial interactions co-exist. It is well-known that polymer chains at the liquid-like free surface tend to have a relatively high mobility, but the mobility in the interfacial layer near the substrate depends strongly on the polymer-substrate interaction strength. Accordingly, we tuned the polymer-substrate interaction strength by introducing an amphiphilic sodiumdodecylsulfate (SDS) molecule layer on the CNT sidewalls. The value and sign of Tg deviation were influenced by the competition between the free surface effect and the interfacial interactions. Strong polymer-substrate interactions led to a decrease in the mobility of polymer chains near the substrate and weak polymer-substrate interactions have little influence on the mobility of polymer chains near the substrate. When the polymer-substrate interactions are strong, both the free surface effect and the polymer-substrate interaction are key factors influencing the glass transition temperature. For thin polymer films having weak interactions with substrates, the free surface effect dominates the glass transition behavior and Tgs shows a large reduction. We also observed a double Tg behavior in the thin PS film and found the thickness of the PS film on the substrate was a deciding factor for controlling the spatial variation of Tg.

15.
Gut ; 68(6): 1034-1043, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-30658994

RESUMEN

OBJECTIVE: Pancreatic ductal adenocarcinoma (PDA) has among the highest stromal fractions of any cancer and this has complicated attempts at expression-based molecular classification. The goal of this work is to profile purified samples of human PDA epithelium and stroma and examine their respective contributions to gene expression in bulk PDA samples. DESIGN: We used laser capture microdissection (LCM) and RNA sequencing to profile the expression of 60 matched pairs of human PDA malignant epithelium and stroma samples. We then used these data to train a computational model that allowed us to infer tissue composition and generate virtual compartment-specific expression profiles from bulk gene expression cohorts. RESULTS: Our analysis found significant variation in the tissue composition of pancreatic tumours from different public cohorts. Computational removal of stromal gene expression resulted in the reclassification of some tumours, reconciling functional differences between different cohorts. Furthermore, we established a novel classification signature from a total of 110 purified human PDA stroma samples, finding two groups that differ in the extracellular matrix-associated and immune-associated processes. Lastly, a systematic evaluation of cross-compartment subtypes spanning four patient cohorts indicated partial dependence between epithelial and stromal molecular subtypes. CONCLUSION: Our findings add clarity to the nature and number of molecular subtypes in PDA, expand our understanding of global transcriptional programmes in the stroma and harmonise the results of molecular subtyping efforts across independent cohorts.


Asunto(s)
Adenocarcinoma/patología , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/patología , Regulación Neoplásica de la Expresión Génica , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patología , Adenocarcinoma/genética , Adenocarcinoma/cirugía , Carcinoma Ductal Pancreático/cirugía , Estudios de Casos y Controles , Simulación por Computador , Matriz Extracelular/patología , Perfilación de la Expresión Génica , Humanos , Microdisección , Neoplasias Pancreáticas/cirugía , Sensibilidad y Especificidad
16.
Opt Lett ; 42(23): 5042-5045, 2017 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-29216175

RESUMEN

In this Letter, we propose a fiber-optic radio frequency (RF) transfer based on active phase noise compensation adopting a carrier suppressed double-sideband (CSDSB) signal. The forward CSDSB signal is generated based on the transmitted RF signal at the local site to discriminate from the backward RF signal. The forward and backward signals are transmitted over the same fiber with the same wavelength to guarantee the bidirectional propagation symmetry. The impact of backscattering is efficiently suppressed by electrical filtering at the sites. A 1 GHz signal transfer over a 40 km optical link is performed in a laboratory. The results show that the proposed scheme can improve the short-term stability from 1.9 e-13/s to 3.9 e-14/s in contrast to the scheme with backscattering while reaching a long-term stability of 2.0 e-16/10000 s.

17.
Muscle Nerve ; 56(1): 117-121, 2017 07.
Artículo en Inglés | MEDLINE | ID: mdl-27750387

RESUMEN

INTRODUCTION: Duchenne and Becker muscular dystrophies (DMD and BMD) are X-linked myopathies caused by mutations of the dystrophin gene. METHODS: Multiplex ligation-dependent probe amplification (MLPA) combined with next-generation sequencing (NGS) of the exons of the dystrophin gene were performed in 92 suspected DMD/BMD patients. Patients with negative results were subjected to additional muscle diseases panel tests. RESULTS: DNA rearrangements were detected in 65 (70.65%) patients using MLPA. The deletions primarily clustered at exons 45-55, followed by exons 2-19. The duplication locations were in contrast to previous studies, which involved the 3' end of the gene. A total of 21 cases with point mutations were detected by NGS analysis. Furthermore, 6 previously unreported mutations were detected. Limb-girdle muscular dystrophy was confirmed in 2 patients after analysis with the muscle diseases panel. CONCLUSIONS: MLPA combined with NGS was effective for detection of the mutations in dystrophin gene exons. Muscle Nerve 56: 117-121, 2017.


Asunto(s)
Distrofina/genética , Distrofia Muscular de Duchenne/genética , Mutación/genética , Niño , Preescolar , Biología Computacional , Exones/genética , Estudios de Asociación Genética , Humanos , Masculino , Estudios Retrospectivos
18.
Opt Lett ; 41(24): 5672-5675, 2016 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-27973486

RESUMEN

In this Letter, we propose and demonstrate a multi-access fiber-optic radio frequency dissemination with passive phase noise cancelation. A forward phase-conjugated signal is generated at the local site by frequency mixing between the standard signal and the round-trip probe signal. A stable frequency signal is achieved by frequency mixing the tapped forward phase-conjugated signal and the backward probe signal at an arbitrary point along the fiber link. Different wavelengths for forward and backward directions are employed to efficiently suppress the effect of backscattering. At the same time, the increase of bidirectional asymmetry with the increase of user ends is avoided by employing the same wavelengths for all user ends. A multi-access frequency transfer over a 45 km fiber link based on the proposed scheme is demonstrated. The radio frequency signals with relative frequency stabilities of 10-17/20,000 s level are reproduced at two points of 5 and 40 km far from the local site along the fiber link, respectively.

19.
Comput Methods Programs Biomed ; 254: 108278, 2024 Jun 11.
Artículo en Inglés | MEDLINE | ID: mdl-38878360

RESUMEN

BACKGROUND AND OBJECTIVE: Training convolutional neural networks based on large amount of labeled data has made great progress in the field of image segmentation. However, in medical image segmentation tasks, annotating the data is expensive and time-consuming because pixel-level annotation requires experts in the relevant field. Currently, the combination of consistent regularization and pseudo labeling-based semi-supervised methods has shown good performance in image segmentation. However, in the training process, a portion of low-confidence pseudo labels are generated by the model. And the semi-supervised segmentation method still has the problem of distribution bias between labeled and unlabeled data. The objective of this study is to address the challenges of semi-supervised learning and improve the segmentation accuracy of semi-supervised models on medical images. METHODS: To address these issues, we propose an Uncertainty-based Region Clipping Algorithm for semi-supervised medical image segmentation, which consists of two main modules. A module is introduced to compute the uncertainty of two sub-networks predictions with diversity using Monte Carlo Dropout, allowing the model to gradually learn from more reliable targets. To retain model diversity, we use different loss functions for different branches and use Non-Maximum Suppression in one of the branches. The other module is proposed to generate new samples by masking the low-confidence pixels in the original image based on uncertainty information. New samples are fed into the model to facilitate the model to generate pseudo labels with high confidence and enlarge the training data distribution. RESULTS: Comprehensive experiments on the combination of two benchmarks ACDC and BraTS2019 show that our proposed model outperforms state-of-the-art methods in terms of Dice, HD95 and ASD. The results reach an average Dice score of 87.86 % and a HD95 score of 4.214 mm on ACDC dataset. For the brain tumor segmentation, the results reach an average Dice score of 84.79 % and a HD score of 10.13 mm. CONCLUSIONS: Our proposed method improves the accuracy of semi-supervised medical image segmentation. Extensive experiments on two public medical image datasets including 2D and 3D modalities demonstrate the superiority of our model. The code is available at: https://github.com/QuintinDong/URCA.

20.
Macromol Biosci ; : e2400238, 2024 Jun 06.
Artículo en Inglés | MEDLINE | ID: mdl-38843881

RESUMEN

Controlling the growth of microbial consortia is of great significance in the biomedical field. Selective bacterial growth is achieved by fabricating silk inverse opal (SIO) scaffolds with varying pore sizes ranging from 0.3 to 4.5 µm. Pore size significantly influences the growth dynamics of bacteria in both single and mixed-strain cultures. Specially, the SIO-4.5 µm scaffold is observed to be more favorable for cultivating S. aureus, whereas the SIO-0.3 µm scaffold is more suitable for cultivating E. coli and P. aeruginosa. By adjusting the secondary conformation of silk fibroin, the stiffness of the SIO substrate will be altered, which results in the increase of bacteria on the SIO by 16 times compared with that on the silk fibroin film. Manipulating the pore size allows for the adjustment of the S. aureus to P. aeruginosa ratio from 0.8 to 9.3, highlighting the potential of this approach in regulating bacterial culture.

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