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1.
Mol Pharm ; 21(3): 1537-1547, 2024 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-38356224

RESUMO

Mitochondria-targeting photothermal therapy could significantly enhance the tumor cell killing effect. However, since therapeutic reagents need to overcome a series of physiological obstacles to arrive at mitochondria accurately, precise mitochondria-targeting photothermal therapy still faces great challenges. In this study, we developed a self-delivery nanoplatform that specifically targeted the mitochondria of tumor cells for precise photothermal therapy. Photothermal agent IR780 was encapsulated by amphiphilic apoptotic peptide KLA with mitochondria-targeting ability to form nanomicelle KI by self-assembly through hydrophilic and hydrophobic interactions. Subsequently, negatively charged tumor-targeting polymer HA was coated on the surface of KI through electrostatic interactions, to obtain tumor mitochondria-targeting self-delivery nanoplatform HKI. Through CD44 receptor-mediated recognition, HKI was internalizated by tumor cells and then disassembled in an acidic environment with hyaluronidase in endosomes, resulting in the release of apoptotic peptide KLA and photothermal agent IR780 with mitochondria anchoring capacity, which achieved precise mitochondria guidance and destruction. This tumor mitochondria-targeting self-delivery nanoplatform was able to effectively deliver photothermal agents and apoptotic peptides to tumor cell mitochondria, resulting in precise destruction to mitochondria and enhancing tumor cell inhibition at the subcellular organelle level.


Assuntos
Nanopartículas , Neoplasias , Humanos , Terapia Fototérmica , Peptídeos , Mitocôndrias , Apoptose , Nanopartículas/química , Linhagem Celular Tumoral , Fototerapia
2.
Polymers (Basel) ; 15(7)2023 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-37050365

RESUMO

Photothermal therapy directly acting on the nucleus is a potential anti-tumor treatment with higher killing efficiency. However, in practical applications, it is often difficult to achieve precise nuclear photothermal therapy because agents are difficult to accurately anchor to the nucleus. Therefore, it is urgent to develop a nanoheater that can accurately locate the nucleus. Here, we designed an amphiphilic arginine-rich dendritic peptide (RDP) with the sequence CRRK(RRCG(Fmoc))2, and prepared a nucleus-targeting nanoplatform RDP/I by encapsulating the photothermal agent IR780 in RDP for precise photothermal therapy of the tumor nucleus. The hydrophobic group Fmoc of the dendritic peptide provides strong hydrophobic force to firmly encapsulate IR780, which improves the solubility and stability of IR780. Moreover, the arginine-rich structure facilitates cellular uptake of RDP/I and endows it with the ability to quickly anchor to the nucleus. The nucleus-targeting nanoplatform RDP/I showed efficient nuclear enrichment ability and a significant tumor inhibition effect.

3.
J Environ Manage ; 340: 117999, 2023 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-37119633

RESUMO

Electrolytic Manganese Residue (EMR) is a solid waste containing soluble sulfate, discharged by electrolytic manganese industries. The accumulation of EMR in ponds poses a significant hazard to both safety and the environment. This study utilized innovative geotechnical test techniques to conduct a series of tests, investigating the effect of soluble salts on the geotechnical characteristics of EMR. The results revealed that soluble sulfates had a significant impact on the geotechnical characteristics of the EMR. In particular, the infiltration of water leached away the soluble salts, causing a non-uniform particle size distribution and decreasing the shear strength, stiffness, and liquefaction resistance of the EMR. Nevertheless, an increase in the stacking density of EMR could improve its mechanical characteristics and inhibited the dissolution of soluble salts. Therefore, increasing the density of stacked EMR, ensuring the effectiveness and non-obstruction of the water interception facilities, and reducing rainwater infiltration could be effective measures to enhance the safety and reduce the environmental hazard of EMR ponds.


Assuntos
Manganês , Sais , Manganês/química , Eletrólitos/química , Resíduos Sólidos/análise , Água
4.
Immunol Res ; 71(4): 528-536, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-36933165

RESUMO

According to Elie Metchnikoff, an originator of modern immunology, several pivotal functions for disease and health are provided by indigenous microbiota. Nonetheless, important mechanistic insights have been elucidated more recently, owing to the growing availability of DNA sequencing technology. There are 10 to 100 trillion symbiotic microbes (such as viruses, bacteria, and yeast) in each human gut microbiota. Both locally and systemically, the gut microbiota has been demonstrated to impact immune homeostasis. Primary B-cell immunodeficiencies (PBIDs) are a group of primary immunodeficiency diseases (PIDs) referring to the dysregulated antibody production due to either intrinsic genetic defects or failures in functions of B cells. Recent studies have found that PBIDs cause disruptions in the gut's typical homeostatic systems, resulting in inadequate immune surveillance in the gastrointestinal (GI) tract, which is linked to increased dysbiosis, which is characterized by a disruption in the microbial homeostasis. This study aimed to review the published articles in this field to provide a comprehensive view of the existing knowledge about the crosstalk between the gut microbiome and PBID, the factors shaping the gut microbiota in PBID, as well as the potential clinical approaches for restoring a normal microbial community.


Assuntos
Disbiose , Microbioma Gastrointestinal , Humanos , Linfócitos B , Reações Cruzadas , Homeostase , Saccharomyces cerevisiae
5.
IEEE Trans Biomed Circuits Syst ; 16(6): 1075-1094, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36459601

RESUMO

Conventional electromagnetic (EM) sensing techniques such as radar and LiDAR are widely used for remote sensing, vehicle applications, weather monitoring, and clinical monitoring. Acoustic techniques such as sonar and ultrasound sensors are also used for consumer applications, such as ranging and in vivo medical/healthcare applications. It has been of long-term interest to doctors and clinical practitioners to realize continuous healthcare monitoring in hospitals and/or homes. Physiological and biopotential signals in real-time serve as important health indicators to predict and prevent serious illness. Emerging electromagnetic-acoustic (EMA) sensing techniques synergistically combine the merits of EM sensing with acoustic imaging to achieve comprehensive detection of physiological and biopotential signals. Further, EMA enables complementary fusion sensing for challenging healthcare settings, such as real-world long-term monitoring of treatment effects at home or in remote environments. This article reviews various examples of EMA sensing instruments, including implementation, performance, and application from the perspectives of circuits to systems. The novel and significant applications to healthcare are discussed. Three types of EMA sensors are presented: (1) Chip-based radar sensors for health status monitoring, (2) Thermo-acoustic sensing instruments for biomedical applications, and (3) Photoacoustic (PA) sensing and imaging systems, including dedicated reconstruction algorithms were reviewed from time-domain, frequency-domain, time-reversal, and model-based solutions. The future of EMA techniques for continuous healthcare with enhanced accuracy supported by artificial intelligence (AI) is also presented.


Assuntos
Inteligência Artificial , Tecnologia de Sensoriamento Remoto , Acústica , Fenômenos Eletromagnéticos , Atenção à Saúde
6.
Adv Mater ; 34(47): e2207016, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36134530

RESUMO

Tactile technologies that can identify human body features are valuable in clinical diagnosis and human-machine interactions. Previously, cutting-edge tactile platforms have been able to identify structured non-living objects; however, identification of human body features remains challenging mainly because of the irregular contour and heterogeneous spatial distribution of softness. Here, freestanding and scalable tactile platforms of force-softness bimodal sensor arrays are developed, enabling tactile gloves to identify body features using machine-learning methods. The bimodal sensors are engineered by adding a protrusion on a piezoresistive pressure sensor, endowing the resistance signals with combined information of pressure and the softness of samples. The simple design enables 112 bimodal sensors to be integrated into a thin, conformal, and stretchable tactile glove, allowing the tactile information to be digitalized while hand skills are performed on the human body. The tactile glove shows high accuracy (98%) in identifying four body features of a real person, and four organ models (healthy and pathological) inside an abdominal simulator, demonstrating identification of body features of the bimodal tactile platforms and showing their potential use in future healthcare and robotics.


Assuntos
Tecnologia Háptica , Robótica , Humanos , Tato , Mãos , Fenômenos Mecânicos
7.
Polymers (Basel) ; 14(7)2022 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-35406338

RESUMO

Basalt fiber is a new environmentally-friendly material with excellent potential for soil reinforcement in geotechnical engineering construction. This study explores the effects of freeze-thaw cycles on the unconfined compressive strength (UCS) and P-wave velocity (Vp) of lime-stabilized basalt fiber-reinforced loess. Reinforced loess samples with different proportions of basalt fiber and lime were subjected to 0, 1, 5, and 10 freeze-thaw cycles, and their UCS and Vp were subsequently measured. The test results showed that the addition of basalt fiber and lime to loess could enhance strength and improve resistance against freeze-thaw damage, and the freeze-thaw damage of reinforced loess decreases with the increase of basalt fiber content and length. A relationship between UCS and Vp of the reinforced samples was obtained for the same number of freeze-thaw cycles, and this relationship exhibited linear characteristics. The fitting results indicate that the Vp can be used to estimate the UCS after freeze-thaw damage. The research results not only have important practical significance in the application of basalt fiber in geotechnical engineering but also provide a reference for the non-destructive testing of the strength of loess after freeze-thaw cycles.

8.
IEEE Trans Biomed Circuits Syst ; 16(1): 138-152, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-35077367

RESUMO

Empowered by the rapid advancements of semiconductor techniques, emerging areas such as industry 4.0, precise healthcare, pervasive communications, intelligent robots, and smart buildings are to be realized, which put substantial demands on low-power and high-performance cognitive edge sensors. Capabilities of precise sensing and seamless interactions with human subjects are pivotal to boosting versatile Internet of Everything (IoE) applications. However, it is challenging to attain various kinds of intuitive sensing based on one edge sensor. A novel silicon-based phased-array coherent radar sensing platform is proposed to attain versatile application-driven capabilities by focusing the wideband radar beams accurately at the target's direction to attain precise sensing. The coherent radar platform can support a maximum 60° field-of-view sensing range with smaller than 2° optimum steering step resolution and -70-dBm sensitivity. The silicon-based mixed-signal coherent radar chip platform is fabricated by a 65-nm CMOS process and owns the convenience for massive deployments at the edge. A series of experiments were conducted to validate the integrated radar platform's adaptable capabilities and salient performances on human subject detection, vital signs monitoring, and motion recognition. Notably, the adaptable multifunction integrated radar platform opens up the enticing possibility for next-generation monolithic edge devices supporting seamless health sensing and cognitive interactive functions with human subjects.


Assuntos
Radar , Silício , Cognição , Humanos , Sujeitos da Pesquisa , Processamento de Sinais Assistido por Computador
9.
Adv Mater ; 34(25): e2104078, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34423476

RESUMO

Simple and rapid Young's modulus measurements of soft materials adaptable to various scenarios are of general significance, and they require miniaturized measurement platforms with easy operation. Despite the advances made in portable and wearable approaches, acquiring and analyzing multiple or complicated signals necessitate tethered bulky components and careful preparation. Here, a new methodology based on a self-locked stretchable strain sensor to haptically quantify Young's modulus of soft materials (kPa-MPa) rapidly is reported. The method demonstrates a fingertip measurement platform, which endows a prosthetic finger with human-comparable haptic behaviors and skills on elasticity sensing without activity constraints. A universal strategy is offered toward ultraconvenient and high-efficient Young's modulus measurements with wide adaptability to various fields for unprecedented applications.


Assuntos
Técnicas de Imagem por Elasticidade , Módulo de Elasticidade , Elasticidade , Técnicas de Imagem por Elasticidade/métodos , Humanos
10.
Anal Cell Pathol (Amst) ; 2021: 6692022, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34211824

RESUMO

Abnormal expressions of long noncoding RNAs (lncRNAs) and protein-encoding messenger RNAs (mRNAs) are important for the development of childhood acute lymphoblastic leukemia (ALL). This study developed an lncRNA-mRNA integrated classifier for the prediction of recurrence and prognosis in relapsed childhood ALL by using several transcriptome data. Weighted gene coexpression network analysis revealed that green, turquoise, yellow, and brown modules were preserved across the TARGET, GSE60926, GSE28460, and GSE17703 datasets, and they were associated with clinical relapse and death status. A total of 184 genes in these four modules were differentially expressed between recurrence and nonrecurrence samples. Least absolute shrinkage and selection operator analysis showed that seven genes constructed a prognostic signature (including one lncRNA: LINC00652 and six mRNAs: INSL3, NIPAL2, REN, RIMS2, RPRM, and SNAP91). Kaplan-Meier curve analysis observed that patients in the high-risk group had a significantly shorter overall survival than those of the low-risk group. Receiver operating characteristic curve analysis demonstrated that this signature had high accuracy in predicting the 5-year overall survival and recurrence outcomes, respectively. LINC00652 may function by coexpressing with the above prognostic genes (INSL3, SNAP91, and REN) and lipid metabolism-related genes (MIA2, APOA1). Accordingly, this lncRNA-mRNA-based classifier may be clinically useful to predict the recurrence and prognosis for childhood ALL. These genes represent new targets to explain the mechanisms for ALL.


Assuntos
Leucemia-Linfoma Linfoblástico de Células Precursoras , RNA Longo não Codificante , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Regulação Neoplásica da Expressão Gênica , Humanos , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Prognóstico , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo
11.
Environ Sci Pollut Res Int ; 28(47): 67565-67576, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34258702

RESUMO

Surface deposition has been widely used in the mining industry to manage mill tailings. Tailings are generally discharged in the form of a slurry into tailings ponds. The slurried tailings are deposited in layers that undergo complex processes, e.g. evaporation, desiccation and consolidation. The evaporation of the deposited tailings controls their geotechnical engineering behaviour, which is necessary to characterise the physical properties. In this study, a constant temperature device was employed in evaporation tests to investigate two classes of deposited tailings, and the effects of the initial concentration, particle size, exposure area and deposited layer thickness on the evaporation processes were analysed. The test results showed four stages in the evaporation processes of deposited coarse and fine tailings. Dewatering of the deposited tailings occurred during the first two stages, which were keys to improving the desiccation efficiency of the tailings in the pond. The exposure area and deposited layer thickness also had a considerable influence on evaporation. The evaporation rate increased with the exposure area and layer thickness. Direct shear tests were performed to measure the shear strength of intact tailings during evaporation and used to determine the variation law of the mechanical properties of the test tailings.


Assuntos
Laboratórios , Lagoas
12.
IEEE Trans Biomed Circuits Syst ; 15(4): 666-678, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-33877986

RESUMO

For precise health status monitoring and accurate disease diagnostics in the current COVID-19 pandemic, it is essential to detect various kinds of target signals robustly under high noise and strong interferences. Moreover, the health monitoring system is preferred to be realized in a small form factor for convenient mass deployments. A CMOS-integrated coherent sensing platform is proposed to achieve the goal, which synergetically leverages quadrature coherent photoacoustic (PA) detection and coherent radar sensing for achieving universal healthcare. By utilizing configurable mixed-signal quadrature coherent PA detection, high sensitivity and enhanced specificity can be achieved. In-phase (I) and quadrature (Q) templates are specifically designed to accurately sense and precisely reconstruct the target PA signals in a coherent mode. By mixed-signal implementation leveraging an FPGA to generate template waveforms adaptively, accurate tracking and precise reconstruction on the target PA signal can be attained based on the early-late tracking principle. The multiplication between the received PA signal and the templates is implemented efficiently in analog-domain by the Gilbert cell on-chip. In vivo blood temperature monitoring was realized based on the integrated PA sensing platform fabricated in a 65-nm CMOS process. With an integrated radar sensor deployed in the indoor scenario, noncontact monitoring on respiration and heartbeat rates can be attained based on electromagnetic (EM) sensing. By complementary usage of PA-EM sensing mechanisms, comprehensive health status monitoring and precise remote disease diagnostics can be achieved for the currentglobal COVID-19 pandemic and the future pervasive healthcare in the Internet of Everything (IoE) era.


Assuntos
Temperatura Corporal , COVID-19 , Radar , Processamento de Sinais Assistido por Computador , Sinais Vitais , Humanos , Pandemias
13.
Environ Sci Pollut Res Int ; 28(14): 17468-17481, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33394448

RESUMO

Phosphogypsum (PG) is a solid waste product of the wet-process phosphoric acid industry that accumulates in large amounts on the ground, forming PG ponds. In recent years, the amount of PG produced and discharged into ponds has increased significantly with the increase in the market demand for phosphate fertilizers. To enrich the basic knowledge of PG properties and provide basic data for the stability analysis of PG dams, a series of laboratory geotechnical tests, including permeability tests, compressibility tests, triaxial shear tests, and dynamic triaxial tests, were conducted in this study. During the preparation of the test samples, solubility and high-temperature dehydration of PG were considered. The results indicated that PG exhibits medium compressibility and medium to weak permeability characteristics. The stress-strain curves of the triaxial shear tests were divided into three typical stages: initial deformation stage, strain hardening stage, and destruction stage. With increasing dry density and consolidation confining pressure, both the shear strength and deformation modulus significantly increased. The relationship between the deformation modulus and confining pressure gradually changed from linear to logarithmic with increasing density. The liquefaction resistance curves (CSR-NL curves) of PG were expressed by power functions. With increasing dry density, the curves shifted higher and became steeper. Compared with the Hardin-Drnevich model, the Davidenkov model was found to be more suitable for describing the relationship between the dynamic shear modulus ratio and damping ratio of PG and the dynamic shear strain. Furthermore, compared with those of tailings and natural soils, the engineering mechanical properties of PG were relatively poor, which may be related to its uniform particle distribution and neat particle stacking structure.


Assuntos
Eliminação de Resíduos , Sulfato de Cálcio , Fósforo , Resistência ao Cisalhamento , Resíduos Sólidos/análise
14.
RSC Adv ; 11(30): 18381-18386, 2021 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-35480930

RESUMO

Carbon-based fluorescent security labels are effective methods to prevent counterfeiting. However, the properties of poor optical stability, complex and energy-consuming synthesis processes and weak bonding with substrates of carbon-based fluorescent materials limit their application prospects. Here, a novel in situ fluorescent patterning strategy is developed to achieve covert, chemically stable and solvent-tolerant cellulose-based security labels by UV exposure. The unsaturated double bonds as the origin of the fluorescence were generated during the photodegradation process under UV exposure. The fluorescent emission of cellulose-based materials reveals excellent stability under acidic, alkaline, reducing, oxidizing and non-polar solvent environments. These advantages give the cellulose nanofiber based security label fantastic potential applications.

15.
Environ Sci Pollut Res Int ; 27(8): 8046-8057, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31897984

RESUMO

The co-placement of mine tailings and fly ash (CMF) can reduce acid mine drainage (AMD) production and decrease metal mobilization. This aids in waste management construction. However, few people have studied a large number of tailing sand-fly ash mixtures under the condition of neutral saturated solution in tailing ponds, wherein the pozzolanic reaction is highly gradual. In this study, a series of tests were conducted to determine the monotonic and cyclic shear characteristics of a mixture of fly ash and tailings. In particular, the effects of the fly ash content on the monotonic shear peak, shear strength parameters, dynamic modulus, and damping ratio of the mixture were analyzed. The results reveal that in a monotonic shear test, the peak shear strength of the saturated CMF mixture decreases as the fly ash content increases. The shear strength parameters (cohesion c and internal friction angle φ) were observed to increase and decrease linearly, respectively, as the fly ash content increased. Furthermore, the maximum dynamic shear modulus was observed to decrease by 41.4% as the fly ash content increased from 0 to 50%, during the cyclic cutting process. Moreover, the experimental results fit well with the fitting formula for the variation in shear modulus in the cyclic shear process of the saturated CMF mixture with varying fly ash content. Meanwhile, the initial damping ratio of the cyclic shear was observed to increase from 10.3 to 13.6% as the fly ash content increased. Therefore, when the CMF method is used to treat AMD waste, it is necessary to consider the extent to which the design stability of the tailing pond may be reduced. These experimental results can be used as a reference for similar CMF projects.


Assuntos
Cinza de Carvão/química , Poluentes Ambientais , Gerenciamento de Resíduos , Cinza de Carvão/análise , Mineração/normas , Areia
16.
Clin Chim Acta ; 502: 191-198, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31904350

RESUMO

B7 homolog 6 (B7-H6) has been identified as involved in tumorigenesis. Elucidating its role and potential mechanism of action is essential for understanding tumorigenesis and the potential development of an effective clinical strategy. Abnormal overexpression of B7-H6 in various types of tumors was reported to be linked with poor prognosis. B7-H6 suppresses the initiation of the "caspase cascade" and induces anti-apoptosis by STAT3 pathway activation to provoke tumorigenesis. B7-H6 facilitates tumor proliferation and cell cycle progression by regulating apoptosis suppressors. B7-H6 induces cellular cytotoxicity, secretion of TNF-α and IFN-γ and B7-H6-specific BiTE triggers T cells to accelerate tumorigenesis. B7-H6 induces abnormal immunological progression by HER2-scFv mediated ADCC and NKp30 immune escape to promote tumorigenesis. B7-H6 promotes tumorigenesis via apoptosis inhibition, proliferation and immunological progression. B7-H6 may a valuable potential biomarker and therapeutic strategy for diagnostics, prognostics and treatment in cancer.


Assuntos
Antígenos B7/imunologia , Neoplasias/imunologia , Humanos , Neoplasias/patologia
17.
IEEE Trans Biomed Circuits Syst ; 13(6): 1405-1416, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31562104

RESUMO

Monolithic integration of photoacoustic (PA) sensor with compact size, lightweight, and low power consumption is attractive to be implemented on wearable medical devices for in vivo blood metabolic sensing and imaging. This work presents a miniaturized chip-scale mixed-signal photoacoustic sensor system which can achieve coherent lock-in function to detect weak target PA signals noninvasively at in vivo scenarios of poor signal to noise ratio (SNR) and strong interferences. A low-noise amplifier (LNA), a 3rd order Butterworth low-pass filter (LPF), and a variable-gain amplifier (VGA) chain with 10 MHz cutoff frequency are implemented on-chip to attain a high-quality sensing performance with 50-dB dynamic range. A Gilbert-cell type multiplier is integrated on-chip to fulfill the coherent lock-in process on acquired PA signals in a closed-loop process with an embedded FPGA system. Fabricated in 65-nm CMOS technology, the prototype PA sensor system demonstrated 50 µV sensitivity. The functions of the chip-scale PA sensor system enhanced by coherent lock-in process were validated through the experiments on temperature monitoring and vessel imaging. The PA receiver chip occupies an area of 0.6 mm2 and consumes 20 mW at a 1.8-V supply.


Assuntos
Técnicas Biossensoriais/instrumentação , Vasos Sanguíneos/diagnóstico por imagem , Temperatura Corporal , Técnicas Fotoacústicas , Amplificadores Eletrônicos , Técnicas Biossensoriais/métodos , Desenho de Equipamento , Humanos , Lasers de Estado Sólido , Semicondutores , Razão Sinal-Ruído
18.
Sensors (Basel) ; 19(16)2019 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-31426550

RESUMO

Vehicular ad hoc networks (VANETs) are an emerging type of mobile ad hoc networks (MANETs) with robust applications in intelligent traffic management systems. VANET has drawn significant attention from the wireless communication research community and has become one of the most prominent research fields in intelligent transportation system (ITS) because of the potential to provide road safety and precautionary measures for the drivers and passengers. In this survey, we discussed the basic overview of the VANET from the architecture, communication methods, standards, characteristics, and VANET security services. Second, we presented the threats and attacks and the recent state-of-the-art methods of the VANET security services. Then, we comprehensively reviewed the authentication schemes that can protect vehicular networks from malicious nodes and fake messages. Third, we discussed the latest simulation tools and the performance of the authentication schemes in terms of simulation tools, which was followed by the VANET applications. Lastly, we identified the open research challenges and gave future research directions. In sum, this survey fills the gap of existing surveys and summarizes the latest research development. All the security attacks in VANETs and their related countermeasures are discussed with respect to ensuring secure communication. The authentication schemes and comprehensive applications were introduced and analyzed in detail. In addition, open research challenges and future research directions were issued.

19.
Environ Sci Pollut Res Int ; 26(25): 26397-26403, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31342351

RESUMO

The physical and mechanical properties of the dielectric materials mainly depend on shapes of particles in granular media. In order to reveal the differences of physical and mechanical properties between tailings and natural sands from the microscopic view, the usage of digital image processing techniques contributes to the quantification of shape descriptors (elongation, sphericity, convexity, and roughness) describing the shapes of particles. The comparison between four tailings (gold, tin, copper, and iron) and two natural sands (river sand and sea sand) is made in the current study. Results show that particle shape descriptors have great relationship with particle size. The decrement of particle size, on one hand, leads to the increase of the elongation of tailings and sea sand, and thus forming the needle-like or columnar shape of particles. The sphericity of tailings and river sand also increases and generates spherical shapes of particles. On the other hand, both of the convexity and roughness of tailings and sea sand grow with larger particle size. The remarkable difference can be observed on surface texture of particles between tailings and sea sand. Much higher angularity of tailings is also represented by comparing with that of sea sand and river sand.


Assuntos
Processamento de Imagem Assistida por Computador , Mineração , Tamanho da Partícula , Cobre , Ouro , Ferro , Dióxido de Silício , Estanho
20.
Artigo em Inglês | MEDLINE | ID: mdl-30917516

RESUMO

Rainfall has been identified as one of the main causes for slope failures in areas where high annual rainfall is experienced. The slope angle is important for its stability during rainfall. This paper aimed to determine the impact of the angle of soil slope on the migration of wetting front in rainfall. The results proved that under the same rainfall condition, more runoff was generated with the increase of slope angle, which resulted in more serious erosion of the soil and the ascent of wetting front. A modified Green-Ampt (GA) model of wetting front was also proposed considering the seepage in the saturated zone and the slope angle. These findings will provide insights into the rainfall-induced failure of soil slopes in terms of angle.


Assuntos
Modelos Teóricos , Chuva , Solo , China , Movimentos da Água
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