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1.
PLoS Pathog ; 18(12): e1011036, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36480554

RESUMO

Serine/arginine-rich (SR) proteins are well known as splicing factors in humans, model animals and plants. However, they are largely unknown in regulating pre-mRNA splicing of filamentous fungi. Here we report that the SR protein MoSrp1 enhances and suppresses alternative splicing in a model fungal plant pathogen Magnaporthe oryzae. Deletion of MoSRP1 caused multiple defects, including reduced virulence and thousands of aberrant alternative splicing events in mycelia, most of which were suppressed or enhanced intron splicing. A GUAG consensus bound by MoSrp1 was identified in more than 94% of the intron or/and proximate exons having the aberrant splicing. The dual functions of regulating alternative splicing of MoSrp1 were exemplified in enhancing and suppressing the consensus-mediated efficient splicing of the introns in MoATF1 and MoMTP1, respectively, which both were important for mycelial growth, conidiation, and virulence. Interestingly, MoSrp1 had a conserved sumoylation site that was essential to nuclear localization and enhancing GUAG binding. Further, we showed that MoSrp1 interacted with a splicing factor and two components of the exon-joining complex via its N-terminal RNA recognition domain, which was required to regulate mycelial growth, development and virulence. In contrast, the C-terminus was important only for virulence and stress responses but not for mycelial growth and development. In addition, only orthologues from Pezizomycotina species could completely rescue defects of the deletion mutants. This study reveals that the fungal conserved SR protein Srp1 regulates alternative splicing in a unique manner.


Assuntos
Processamento Alternativo , Ascomicetos , Proteínas Fúngicas , Oryza , Ascomicetos/genética , Oryza/microbiologia , Fatores de Processamento de Serina-Arginina/genética , Proteínas Fúngicas/genética
2.
Sensors (Basel) ; 23(17)2023 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-37687873

RESUMO

The performance of the calorimetric microflow sensor is closely related to the thermal sensing part design, including structure parameter, heater temperature, and operation environment. In this paper, several measures to enhance the performance of the calorimetric microflow sensor were proposed and further verified by numerical simulations. The results demonstrate that it is more favorable to reduce the negative impact of flow separation as the space between detectors and heater is set to be 1.6 µm so as to improve the accuracy of the sensor. With an appropriate gap, the front arranged obstacle of the upstream detector can effectively widen the measure range of the sensor, benefiting from the decrease in upstream viscous dissipation. Compared to a cantilever structure, the resonances can be effectively suppressed when the heater and detectors are designed as bridge structures. In particular, the maximum amplitude of the bridge structure is only 0.022 µm at 70 sccm, which is 53% lower than that of the cantilever structure. The optimized sensor widens the range by 14.3% and significantly increases the sensitivity at high flow rates. Moreover, the feasibility of the improved measures is also illustrated via the consistency of the trend between the simulation results and experimental ones.

3.
J Prosthet Dent ; 129(1): 230-233, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34011442

RESUMO

The digital fabrication of a maxillary obturator with a 3D-printed polyetheretherketone (PEEK) framework is described. Digital oral data were scanned for the computer-aided design (CAD) of the framework and the 3D printing of a preliminary resin cast. The framework was accurately printed from a PEEK filament material. A secondary impression was made to fabricate the definitive cast. The PEEK framework exhibited precise fit, excellent retention, and reduced weight compared with a typical metal framework.


Assuntos
Prótese Maxilofacial , Polímeros , Benzofenonas , Polietilenoglicóis , Desenho Assistido por Computador , Impressão Tridimensional , Cetonas
4.
Environ Microbiol ; 23(10): 5901-5916, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34056823

RESUMO

The splicing factor Cwf15 is an essential component of the Prp19-associated component of the spliceosome and regulates intron splicing in several model species, including yeasts and human cells. However, the roles of Cwf15 remain unexplored in plant pathogenic fungi. Here, we report that MoCWF15 in the rice blast fungus Magnaporthe oryzae is non-essential to viability and important to fungal virulence, growth and conidiation. MoCwf15 contains a putative nuclear localization signal (NLS) and is localized into the nucleus. The NLS sequence but not the predicted phosphorylation site or two sumoylation sites was essential for the biological functions of MoCwf15. Importantly, MoCwf15 physically interacted with the Prp19-associated splicing factors MoCwf4, MoSsa1 and MoCyp1, and negatively regulated protein accumulations of MoCyp1 and MoCwf4. Furthermore, with the deletion of MoCWF15, aberrant intron splicing occurred in near 400 genes, 20 of which were important to the fungal development and virulence. Taken together, MoCWF15 regulates fungal growth and infection-related development by modulating the intron splicing efficiency of a subset of genes in the rice blast fungus.


Assuntos
Magnaporthe , Oryza , Ascomicetos , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Regulação Fúngica da Expressão Gênica , Humanos , Oryza/microbiologia , Doenças das Plantas/microbiologia , Fatores de Processamento de RNA/genética , Fatores de Processamento de RNA/metabolismo , Esporos Fúngicos/metabolismo , Virulência/genética
5.
Entropy (Basel) ; 23(10)2021 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-34682049

RESUMO

Calculation of the thermal conductivity of nanofluids by molecular dynamics (MD) is very common. Regrettably, general MD can only be employed to simulate small systems due to the huge computation workload. Instead, the computation workload can be considerably reduced due to the coarse-grained fluid when multiparticle collision dynamics (MPCD) is employed. Hence, such a method can be utilized to simulate a larger system. However, the selection of relevant parameters of MPCD noticeably influences the calculation results. To this end, parameterization investigations for various bin sizes, number densities, time-steps, rotation angles and temperatures are carried out, and the influence of these parameters on the calculation of thermal conductivity are analyzed. Finally, the calculations of thermal conductivity for liquid argon, water and Cu-water nanofluid are performed, and the errors compared to the theoretical values are 3.4%, 1.5% and 1.2%, respectively. This proves that the method proposed in the present work for calculating the thermal conductivity of nanofluids is applicable.

6.
Langmuir ; 36(4): 919-930, 2020 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-31886672

RESUMO

The evaporation behaviors of droplet containing nanoparticles play an important role in nanofluid combustion, spray drying, and so on. The average evaporation rate of a nanofluid droplet will decrease sharply at the end stage of droplet evaporation because the aggregation of nanoparticles on the surface of the droplet results in a shell. To illustrate the microscopic mechanism for the variation of the average evaporation rate and surface tension caused by the copper nanoparticles on the surface of the water droplet, numerical simulations based on the Brownian dynamics are conducted to study the effects of nanoparticle behaviors on the average evaporation rate and surface tension for various initial volume fractions and various distributions of nanoparticles. The results show us that the nanoparticles' distribution and the initial volume fraction of nanoparticles will greatly affect the average evaporation rate of the nanofluid droplet. Therefore, a Dh law can be expected due to the effects of added copper nanoparticles on the evaporation behavior where h will vary with the initial volume fraction and distribution of nanoparticles. Comparisons to the published results indicate that the exponent h = 2.0 for pure liquid, h < 2.0 when lyophilic nanoparticles are added, and h > 2.0 when lyophobic nanoparticles are added. In general, the most important factors to affect the evaporation rate are the volume fraction, distribution, and lyophilic nature of nanoparticles.

7.
Mol Cell Proteomics ; 16(9): 1669-1682, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28706003

RESUMO

Protein phosphorylation is known to regulate pathogenesis, mycelial growth, conidiation and stress response in Pyricularia oryzae However, phosphorylation mediated regulatory networks in the fungal pathogen remain largely to be uncovered. In this study, we identified 1621 phosphorylation sites of 799 proteins in mycelia of P. oryzae, including 899 new p-sites of 536 proteins and 47 new p-sites of 31 pathogenicity-related proteins. From the sequences flanking the phosphorylation sites, 19 conserved phosphorylation motifs were identified. Notably, phosphorylation was detected in 7 proteins that function upstream of Pmk1, but not in Pmk1 and its downstream Mst12 and Sfl1 that have been known to regulate appressorium formation and infection hyphal growth of P. oryzae Interestingly, phosphorylation was detected at the site Ser240 of Pmp1, which is a putative protein phosphatase highly conserved in filamentous fungi but not characterized. We thus generated Δpmp1 deletion mutants and dominant allele PMP1S240D mutants. Phenotyping analyses indicated that Pmp1 is required for virulence, conidiation and mycelial growth. Further, we observed that phosphorylation level of Pmk1 in mycelia was significantly increased in the Δpmp1 mutant, but decreased in the PMP1S240D mutant in comparison with the wild type, demonstrating that Pmp1 phosphorylated at Ser240 is important for regulating phosphorylation of Pmk1. To our surprise, phosphorylation of Mps1, another MAP kinase required for cell wall integrity and appressorium formation of P. oryzae, was also significantly enhanced in the Δpmp1 mutant, but decreased in the PMP1S240D mutant. In addition, we found that Pmp1 directly interacts with Mps1 and the region AA180-230 of Pmp1 is required for the interaction. In summary, this study sheds new lights on the protein phosphorylation mediated regulatory networks in P. oryzae.


Assuntos
Ascomicetos/metabolismo , Proteínas Fúngicas/metabolismo , Redes Reguladoras de Genes , Micélio/metabolismo , Fosfoproteínas/metabolismo , Proteômica/métodos , Sequência de Aminoácidos , Ascomicetos/patogenicidade , Proteínas Fúngicas/química , Sistema de Sinalização das MAP Quinases , Modelos Biológicos , Fosfopeptídeos/química , Fosfopeptídeos/metabolismo , Fosfoproteínas/química , Fosforilação , Espectrometria de Massas em Tandem , Fatores de Virulência/metabolismo
8.
Arch Virol ; 162(9): 2695-2704, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28578521

RESUMO

Human cytomegalovirus (HCMV) has been reported to be linked to vascular disease through the induction of neovessel formation. We have previously reported that microRNA (miR)-217 and miR-199a-5p enhance endothelial angiogenesis via inhibition of sirtuin 1 (SIRT1) in HCMV-infected human umbilical vein endothelial cells (HUVECs). Here, we found that miR-138 also suppressed the expression of the SIRT1 protein and stimulated phosphorylation of signal transducer and activator of transcription 3 (p-STAT3). Moreover, the regulation of p-STAT3 expression mediated by SIRT1 was found to promote HCMV-induced angiogenesis. These findings revealed that miR-138 might promote angiogenesis of HCMV-infected HUVECs by activating the SIRT1-mediated p-STAT3 pathway, and this could provide novel insights into HCMV-induced angiogenesis.


Assuntos
Citomegalovirus/fisiologia , Células Endoteliais/fisiologia , MicroRNAs/metabolismo , Neovascularização Fisiológica/fisiologia , Fator de Transcrição STAT3/metabolismo , Sirtuína 1/metabolismo , Movimento Celular , Regulação para Baixo , Células Endoteliais/virologia , Regulação da Expressão Gênica , Células Endoteliais da Veia Umbilical Humana , Humanos , MicroRNAs/genética , Fator de Transcrição STAT3/genética , Sirtuína 1/genética , Regulação para Cima
9.
Entropy (Basel) ; 20(1)2017 Dec 25.
Artigo em Inglês | MEDLINE | ID: mdl-33265098

RESUMO

It is necessary to control the temperature of solar cells for enhancing efficiency with increasing concentrations of multiple photovoltaic systems. A heterogeneous two-phase model was established after considering the interacting between temperature, viscosity, the flow of nanofluid, and the motion of nanoparticles in the nanofluid, in order to study the microchannel heat sink (MCHS) using Al2O3-water nanofluid as coolant in the photovoltaic system. Numerical simulations were carried out to investigate the thermal performance of MCHS with a series of trapezoidal grooves. The numerical results showed us that, (1) better thermal performance of MCSH using nanofluid can be achieved from a heterogeneous two-phase model than that from single-phase model; (2) The effects of flow field, volume fraction, nanoparticle size on the heat transfer enhancement in MCHS were interpreted by a non-dimensional parameter NBT (i.e., ratio of Brownian diffusion and thermophoretic diffusion). In addition, the geometrical parameters of MCHS and the physical parameters of the nanofluid were optimized. This can provide a sound foundation for the design of MCHS.

10.
Neurol Sci ; 37(2): 309-13, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25837714

RESUMO

BACKGROUND: Multiple brainstem manifestations have been rarely reported during the same attack in neuromyelitis optica spectrum disorders (NMOSD). CASE PRESENTATION: We describe a 39-year-old Asian woman presenting multiple brainstem manifestations including intractable nausea and vomiting, vertigo, diplopia, facial palsy, hypogeusia, ophthalmoplegia, hemiplegia, dysphagia and tonic spasm during the same attack. Hypogeusia was transient and recovered without any immunotherapy. The brain MRIs showed progressive multiple lesions in the brainstem. NMO-IgG (aquaporin4-antibody, AQP4-Ab) were positive in both serum and cerebral spinal fluid. The symptoms and signs were controlled after immunosuppressive therapy. No relapse happened during the 15-month follow-up. CONCLUSION: This report emphasizes multiple brainstem manifestations during the same attack in NMOSD and the most characteristic symptom was reversible hypogeusia.


Assuntos
Tronco Encefálico/patologia , Neuromielite Óptica/complicações , Neuromielite Óptica/patologia , Adulto , Feminino , Humanos
11.
BMC Neurol ; 15: 107, 2015 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-26152327

RESUMO

BACKGROUND: Anti-N-methyl-D-aspartate receptor encephalitis is a severe autoimmune disorder characterized by severe psychiatric symptoms, seizures, decreased consciousness, autonomic dysregulation, and dyskinesias. Multifocal subcortical white matter lesions on fluid-attenuated inversion recovery and diffuse weighted images have rarely been reported in previous literature, and serial magnetic resonance imaging changes after plasma exchange have not been presented before. CASE PRESENTATION: A previously healthy 24-year-old Chinese woman presented with acute psychiatric symptoms characterized by fear and agitation followed by decreased consciousness, dyskinesias, and seizures. Magnetic resonance imaging revealed hyperintense lesions on fluid-attenuated inversion recovery and diffuse weighted images in bilateral subcortical white matter. Cerebrospinal fluid analysis revealed a mild pleocytosis with lymphocytic predominance. Protein and glucose levels were normal. Aquaporin-4 antibodies in serum and cerebrospinal fluid were negative. Identification of anti-N-methyl-D-aspartate receptor antibodies in serum and cerebrospinal fluid confirmed the diagnosis of anti-N-methyl-D-aspartate receptor encephalitis. She was initially treated with combined intravenous immunoglobulin and methylprednisolone without improvement. Plasma exchange was then initiated with good response; the patient made a full recovery after several cycles of plasma exchange. Repeat magnetic resonance imaging performed 1 month after plasma exchange showed partial resolution of the hyperintense lesions in bilateral subcortical white matter, and follow-up magnetic resonance imaging 2 months after plasma exchange showed complete resolution. CONCLUSION: Anti-N-methyl-D-aspartate receptor encephalitis may be concomitant with multifocal subcortical white matter lesions. Such lesions may resolve after appropriate immunotherapy.


Assuntos
Encefalite Antirreceptor de N-Metil-D-Aspartato/diagnóstico , Imageamento por Ressonância Magnética , Substância Branca/patologia , Encefalite Antirreceptor de N-Metil-D-Aspartato/patologia , Autoanticorpos/sangue , Feminino , Humanos , Imunoglobulinas Intravenosas/administração & dosagem , Imunoterapia , Metilprednisolona/administração & dosagem , Receptores de N-Metil-D-Aspartato/imunologia , Convulsões/etiologia , Adulto Jovem
12.
Arch Virol ; 158(12): 2443-52, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23760629

RESUMO

Human cytomegalovirus (HCMV) infection has been shown to contribute to vascular disease through the induction of angiogenesis. However, the role of microRNA in angiogenesis induced by HCMV infection remains unclear. The present study was thus designed to explore the potential effect of miR-199a-5p on angiogenesis and to investigate the underlying mechanism in endothelial cells. We found that HCMV infection of endothelial cells (ECs) enhanced expression of miR-199a-5p and reduced the SIRT1 protein level at 24 h postinfection (hpi). Transfection with miR-199a-5p mimics significantly suppressed SIRT1 protein expression and promoted cellular migration and tube formation induced by HCMV infection, which could be reversed by transfection with an miR-199a-5p inhibitor. Furthermore, pretreatment with resveratrol depressed motility and tube formation of HCMV-infected ECs, which could be reversed by SIRT1 siRNA. Finally, overexpression of miR-199a-5p decreased the level of eNOS modulated by SIRT1, an effect repressed by transfection with an miR-199a-5p inhibitor. In summary, HCMV infection of endothelial cells upregulates miR-199a-5p expression and enhances cell migration and tube formation through downregulation of SIRT1/eNOS by miR-199a-5p.


Assuntos
Movimento Celular , Infecções por Citomegalovirus/patologia , Células Endoteliais/virologia , MicroRNAs/metabolismo , Neovascularização Patológica , Óxido Nítrico Sintase Tipo III/biossíntese , Sirtuína 1/biossíntese , Regulação para Baixo , Células Endoteliais/fisiologia , Interações Hospedeiro-Patógeno , Humanos
13.
Micromachines (Basel) ; 14(11)2023 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-38004985

RESUMO

The liquid cooling system of lithium battery modules (LBM) directly affects the safety, efficiency, and operational cost of lithium-ion batteries. To meet the requirements raised by a factory for the lithium battery module (LBM), a liquid cooling plate with a two-layer minichannel heat sink has been proposed to maintain temperature uniformity in the module and ensure it stays within the temperature limit. This innovative design features a single inlet and a single outlet. To evaluate the performance of the liquid cooling system, we considered various discharge rates while taking into account the structure, flow rate, and temperature of the coolant. Our findings indicate that at a mass outflow rate of 20 g/s, a better cooling effect and lower power consumption can be achieved. An inlet temperature of 20 °C, close to the initial temperature of the battery string, may be the most appropriate because a higher temperature of the coolant will cause a higher temperature of LBM, so far as to exceed the safe threshold value. In the case of larger rate discharge, the design of a double-layer MCHS at the bottom and an auxiliary one at the side can effectively reduce the maximum temperature LBM (within 28 °C) and maintain the temperature difference in the single cell at approximately 4 °C. In the case of non-constant discharges, the temperature difference between cells increases with the maximum temperature. When the discharge rate is reduced, the large temperature difference helps the temperature to drop rapidly. This can provide guidance for the design of cooling systems for the LBM.

14.
IEEE J Biomed Health Inform ; 27(2): 854-865, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-35259124

RESUMO

Edge intelligent computing is widely used in the fields, such as the Internet of Medical Things (IoMT), which has advantages, including high data processing efficiency, strong real-time performance and low network delay. However, there are many problems including privacy disclosure, limited calculation force, as well as scheduling and coordination issues. Federated learning can greatly improves training efficiency. However, due to the sensitive nature of the healthcare data, the aforementioned approach of transferring the patient's data to the servers may create serious security and privacy issues. Therefore, this article proposes a Privacy Protection Scheme for Federated Learning under Edge Computing (PPFLEC). First of all, we propose a lightweight privacy protection protocol based on a shared secret and weight mask, which is based on a random mask scheme of secret sharing. It is more accurate and efficient than,homomorphic encryption. It can not only protect gradient privacy without losing model accuracy, but also resist equipment dropping and collusion attacks between devices. Second, we design an algorithm based on a digital signature and hash function, which achieves the integrity and consistency of the message, as well as resisting replay attacks. Finally, we propose a periodic average training strategy, compared with differential privacy to prove that our scheme is 40 % faster in efficiency than in deferential privacy. Meanwhile, compared with federated learning, we can achieve the same efficiency under the condition of ensuring safety. Therefore, our scheme can work well in unstable edge computing environments such as smart healthcare.


Assuntos
Internet das Coisas , Privacidade , Humanos , Segurança Computacional , Atenção à Saúde , Algoritmos
15.
IEEE J Biomed Health Inform ; 27(2): 732-743, 2023 02.
Artigo em Inglês | MEDLINE | ID: mdl-36215343

RESUMO

The Internet of Medical Things (IoMT) is an important application of the Internet of Things in health care. In IoMT, efficiency and user privacy are crucial for cloud storage and retrieval of healthcare data documents. Existing schemes, however, often suffer from inefficient retrieval and increased risk of privacy disclosure when dealing with massive data. We propose here a new Efficient Encrypted Parallel Ranking (EEPR) search system, block-based and privacy-preserved, for encrypted cloud healthcare data. We design a parallel binary search tree structure in block and propose a parallel retrieval algorithm adaptable to such a structure. A quantitative analysis through the information retention index shows that our scheme demonstrates better search performance. In addition, feature vectors generated from our scheme are difficult to be reversely analyzed due to unexplainability, enhancing privacy protection for patients and researchers. A formal security analysis shows that our EEPR scheme is resistable to known background attack, and yields a lower time complexity and significantly improves search efficiency as well as accuracy over existing schemes.


Assuntos
Segurança Computacional , Privacidade , Humanos , Armazenamento e Recuperação da Informação , Registros Eletrônicos de Saúde , Algoritmos , Computação em Nuvem , Atenção à Saúde
16.
Neural Netw ; 163: 146-155, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37054513

RESUMO

Deep neural networks are enjoying unprecedented attention and success in recent years. However, catastrophic forgetting undermines the performance of deep models when the training data are arrived sequentially in an online multi-task learning fashion. To address this issue, we propose a novel method named continual learning with declarative memory (CLDM) in this paper. Specifically, our idea is inspired by the structure of human memory. Declarative memory is a major component of long-term memory which helps human beings memorize past experiences and facts. In this paper, we propose to formulate declarative memory as task memory and instance memory in neural networks to overcome catastrophic forgetting. Intuitively, the instance memory recalls the input-output relations (fact) in previous tasks, which is implemented by jointly rehearsing previous samples and learning current tasks as replaying-based methods act. In addition, the task memory aims to capture long-term task correlation information across task sequences to regularize the learning of the current task, thus preserving task-specific weight realizations (experience) in high task-specific layers. In this work, we implement a concrete instantiation of the proposed task memory by leveraging a recurrent unit. Extensive experiments on seven continual learning benchmarks verify that our proposed method is able to outperform previous approaches with tremendous improvements by retaining the information of both samples and tasks.


Assuntos
Aprendizagem , Redes Neurais de Computação , Humanos , Cognição , Rememoração Mental , Aprendizado de Máquina
17.
Micromachines (Basel) ; 14(5)2023 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-37241555

RESUMO

Heterogeneous integration (HI) is a rapidly developing field aimed at achieving high-density integration and miniaturization of devices for complex practical radio frequency (RF) applications. In this study, we present the design and implementation of two 3 dB directional couplers utilizing the broadside-coupling mechanism and silicon-based integrated passive device (IPD) technology. The type A coupler incorporates a defect ground structure (DGS) to enhance coupling, while type B employs wiggly-coupled lines to improve directivity. Measurement results demonstrate that type A achieves <-16.16 dB isolation and <-22.32 dB return loss with a relative bandwidth of 60.96% in the 6.5-12.2 GHz range, while type B achieves <-21.21 dB isolation and <-23.95 dB return loss in the first band at 7-13 GHz, <-22.17 dB isolation and <-19.67 dB return loss in the second band at 28-32.5 GHz, and <-12.79 dB isolation and <-17.02 dB return loss in the third band at 49.5-54.5 GHz. The proposed couplers are well suited for low cost, high performance system-on-package radio frequency front-end circuits in wireless communication systems.

18.
Micromachines (Basel) ; 15(1)2023 Dec 25.
Artigo em Inglês | MEDLINE | ID: mdl-38258165

RESUMO

This review presents a concise overview of RF (radio frequency) power transistor behavior models, which is crucial for optimizing RF performance in high-frequency applications like wireless communication, radar, and satellites. The paper highlights the significance of accurate modeling in understanding transistor behavior and traces the evolution of behavior modeling techniques. Different behavior modeling strategies, such as LUT (look-up table) based models, polynomial equation-based models, and machine learning based models, are discussed along with their unique characteristics and modeling challenges. The review explores the difference between behavior models and the conventional empirical or physics-based modeling approaches, addressing the challenges of the accurate characterization of transistors at high frequencies and power levels. This paper concludes with an outlook of emerging trends, such as physical models combined with behavior models, shaping the future of RF power transistor modeling for more efficient communication systems.

19.
Micromachines (Basel) ; 13(7)2022 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-35888968

RESUMO

The miniaturization of components in mechanical and electronic equipment has been the driving force for the fast development of micro/nanosystems [...].

20.
Micromachines (Basel) ; 13(11)2022 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-36363868

RESUMO

Heat-transfer enhancement in microchannel heat sinks (MCHS) has been a hot topic in the last decade. However, most published works did not focus on the heat sources that are discrete, as in most microelectronic devices, and the enhancement of heat and mass transfer (HMT) due to the Soret and Dufour effects being ignored. Based on a heterogeneous two-phase model that takes into consideration the Soret and Dufour effects, numerical simulations have been performed for various geometries and heat sources. The numerical results demonstrate that the vortices induced by a heat source(s) can enhance the heat transfer efficiency up to 2665 W/m2·K from 2618 W/m2·K for a discrete heat source with a heat flux q = 106 W/m2. The Soret effect can affect the heat transfer much more than the Duffour effect. The integrated results for heat transfer due to the Soret and Dufour effects are not sampled superpositions. Discrete heat sources (DHS) arranged in microchannels can enhance heat transfer, especially when the inlet velocity of the forced flow is less than 0.01 m/s. This can provide a beneficial reference for the design of MCHS with DHS.

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