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1.
Front Pharmacol ; 15: 1399625, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38720781

RESUMO

Objective: To investigate the immune mechanism of osteosarcoma (OS)-specific markers to mitigate bone destruction in the aggressive OS, prone to recurrence and metastasis. Methods: Gene expression patterns from the Gene Expression Omnibus (GEO) database (GSE126209) were analyzed using weighted gene co-expression network analysis (WGCNA), protein-protein interaction (PPI) analysis, least absolute shrinkage and selection operator (LASSO) modeling, and survival analysis to identify charged multivesicular body protein 4C (CHMP4C). Subsequently, its role in regulating the immune system and immune cell infiltration was explored. CHMP4C expression and signaling molecules in OS were assessed in osteosarcoma cell lines (MG63, U2OS, HOS) and hFOB1.19 cells using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and immunofluorescence staining. The impact of CHMP4C upregulation and interference on OS-related signaling molecules in MG63 cells was studied. Functional validation of CHMP4C in MG63 OS cells was confirmed through cell counting Kit-8 (CCK-8), transwell, and colony formation assays. In vivo experiments were conducted using Specific Pathogen Free (SPF)-grade male BALB/C nude mice for OS xenograft studies. Results: Based on the gene expression profiles analysis of six osteosarcoma samples and six normal tissue samples, we identified 1,511 upregulated DEGs and 5,678 downregulated DEGs in normal tissue samples. A significant positive correlation between the "yellow-green" module and OS was found through WGCNA analysis. Expression levels of CHMP4C, phosphorylated Glycogen Synthase Kinase 3ß (p-GSK3ß), and ß-catenin were notably higher in U2OS, HOS, and MG63 OS cells than in hFOB1.19 human osteoblasts. Overexpressing CHMP4C in MG63 OS cells upregulated CHMP4C, p-GSK3ß, and ß-catenin while downregulating GSK3ß, leading to increased proliferation and migration of MG63 cells. Conversely, interrupting CHMP4C had the opposite effect. High expression of CHMP4C significantly accelerated the growth of OS in nude mice, resulting in substantial upregulation of CHMP4C, p-GSK3ß, and ß-catenin expression and suppression of Glycogen Synthase Kinase 3ß (GSK3ß) expression in OS tissues. Conclusion: CHMP4C may serve as a specific immunomodulatory gene for OS. Its activation of the Wnt/ß-catenin signaling pathway, mainly by increasing the phosphorylation echelon of GSK3ß, promotes the invasion and spread of OS.

2.
Hortic Res ; 11(3): uhae031, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38481937

RESUMO

Apple fruit skin color fading is not well understood although the molecular mechanism of skin color formation is well known. The red-fleshed apple cultivar 'Daihong' (DH) exhibited fading skin color during fruit development despite having a heterozygous R6 allele but lacking Red-TE for red fruit skin. In this study, transcriptomic analysis revealed the expression level of MdMYB10 increased with fruit development whereas reduced expression levels of MdMYBPA1, MdCHS, MdANS, MdUFGT, MdLAR, and MdANR were observed, consistent with decreased levels of chalcone, anthocyanin, catechin, epicatechin, and procyanidin B2. Whole-genome bisulfite sequencing (WGBS) indicated a global gain in cytosine methylation levels and increased methylation in 5' and 3' flanking regions of genes and transposable elements (TEs), and in TE bodies in all CG, CHG and CHH contexts, especially the mCHH context, during fruit development. The increased DNA methylation was attributed to reduced expression levels of DNA demethylase genes, including MdDME1, MdROS1, and MdROS2. Association analysis revealed a significant negative correlation between promoter methylation levels of MdCHS, MdCHI, MdMYBPA1, and their respective transcript levels, as well as a negative correlation between promoter methylation levels of MdCHS, MdCHI, MdANR, and MdFLS, and the content of chalcones, naringenin-7-glucoside, epicatechin, and quercetin. Treatment with the DNA demethylation agent 5-aza-2'-deoxycytidine verified the negative correlation between DNA methylation and gene expression within the flavonoid pathway. These findings suggest that hypermethylation in promoter regions of genes of the flavonoid biosynthesis pathway is associated with the reduction of gene expression and flavonoid content, and fruit skin color fading during DH apple development.

3.
Nanotechnology ; 35(24)2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38271718

RESUMO

With the advancements in flexible materials and information technology, flexible sensors are becoming increasingly pervasive in various aspects of life and production. They hold immense potential for further development in areas such as motion detection, electronic skin, soft robots, and wearable devices. Aminopropyl-terminated polydimethylsiloxane (PDMS) was used as the raw material, while a diisocyanate reagent served as the cross-linking agent for the polymerization reaction, which involved the introduction of ureido groups, containing N-H and C=O bonds, into the long siloxane chain. The dynamic hydrogen bonding between the clusters completes the self-healing of the material. Using 1-[3-(trimethoxysilyl)propyl]urea as a grafting agent, the urea groups are introduced into graphene oxide and carbon nanotubes (CNTs) as conductive fillers. Subsequently, a flexible polymer is used as the substrate to prepare conductive flexible self-healing composites. By controlling the amount of conductive fillers, flexible strain materials with varying sensitivities are obtained. Design the structure of the flexible strain sensor using three-dimensional (3D) modeling software with deposition printing method.

4.
Br J Radiol ; 97(1153): 237-248, 2024 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-38263821

RESUMO

OBJECTIVE: To construct prediction models including baseline 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) metabolic parameters of tumoural lesions and non-tumour lymphoid tissue for recurrence-free survival within 5 years (5y-RFS) after imaging examination in patients with invasive ductal carcinomas (IDCs) of the breast. METHODS: The study included 101 consecutive female patients. Univariable and multivariable Cox regression were used to identify clinicopathological and metabolic parameters associated with risk of recurrence. Four prediction models based on the results of multivariable analysis were constructed and visualized as nomograms. Performance of each nomogram was evaluated using the concordance index (C-index), integrated discrimination improvement, decision curve analysis (DCA), and calibration curve. RESULTS: N3 status, total metabolic tumour volume, the maximum standardized uptake value of spleen, and spleen-to-liver ratio were significant predictors of 5y-RFS. The nomogram including all significant predictors demonstrated superior predictive performance for 5y-RFS, with a C-index of 0.907 (95% CI, 0.833-0.981), greatest net benefit on DCA, good accuracy on calibration curves, and excellent risk stratification on Kaplan-Meier curves. CONCLUSIONS: The model that included metabolic parameters of the spleen had the best performance for predicting 5y-RFS in patients with IDCs of the breast. This model may guide personalized treatment decisions and inform patients and clinicians about prognosis. ADVANCES IN KNOWLEDGE: This research identifies 18F-FDG PET/CT metabolic parameters of non-tumour lymphoid tissue as predictors of recurrence in breast cancer.


Assuntos
Neoplasias da Mama , Carcinoma Ductal , Humanos , Feminino , Baço , Fluordesoxiglucose F18 , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Mama
5.
Micromachines (Basel) ; 15(1)2024 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-38258228

RESUMO

Hollow microspheres as the filler material of syntactic foams have been adopted in extensive practical applications, where the physical parameters and their homogeneity have been proven to be critical factors during the design process, especially for high-specification scenarios. Based on double-emulsion droplet templates, hollow microspheres derived from microfluidics-enabled soft manufacturing have been validated to possess well-controlled morphology and composition with a much narrower size distribution and fewer defects compared to traditional production methods. However, for more stringent requirements, the innate density difference between the core-shell solution of the double-emulsion droplet template shall result in the wall thickness heterogeneity of the hollow microsphere, which will lead to unfavorable mechanical performance deviations. To clarify the specific mechanical response of microfluidics-derived hollow silica microspheres with varying eccentricities, a hybrid method combining experimental nanoindentation and a finite element method (FEM) simulation was proposed. The difference in eccentricity can determine the specific mechanical response of hollow microspheres during nanoindentation, including crack initiation and the evolution process, detailed fracture modes, load-bearing capacity, and energy dissipation capability, which should shed light on the necessity of optimizing the concentricity of double-emulsion droplets to improve the wall thickness homogeneity of hollow microspheres for better mechanical performance.

7.
RSC Adv ; 14(5): 3250-3260, 2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-38249672

RESUMO

Colloidal emulsion droplets, created using glass capillary microfluidic devices, have been found in a myriad of applications, serving as subtle microcarriers, delicate templates, etc. To meet the objective requirements under varying circumstances, it is crucial to efficiently control the morphology and dimensions of the droplets on demand. The glass capillary collection tube is a crucial component of the flow-focusing microfluidic system due to its close association with the geometrical confinement of the multiphasic flow. However, there are currently no guidelines for the design of the morphology and dimensions of the glass capillary collection tube, which shall result in a delay in assessing serviceability until after the microfluidic device is prepared, thereby causing a loss of time and effort. Herein, an experimental study was conducted to investigate the effect of the geometrical characteristics of glass capillary collection tubes on the production of colloidal emulsion droplets. After characterizing the generated colloidal emulsion droplets, it was found that the geometrical variations of the glass capillary collection tube resulted in numerical disparities of droplets due to different degrees of flow-focusing effects. The stronger flow-focusing effect produced smaller droplets at a higher frequency, and the dimensional variation of colloidal emulsion droplets was more responsive to varying flow rates. Furthermore, the transformation from colloidal single-core double-emulsion droplets to multi-core double-emulsion droplets also changed with the flow rate due to the glass capillary collection tube morphology-determined varying flow-focusing effect. These experimental findings can offer qualitative guidance for the design of glass capillary microfluidic devices in the preliminary stage, thus facilitating the smooth production of desired colloidal emulsion droplets.

8.
J Clin Endocrinol Metab ; 109(1): e397-e405, 2023 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-37410931

RESUMO

CONTEXT: Body weight and composition may change over the natural menopause transition. Whether surgical menopause has similar effects, and the impact of hormone replacement therapy (HRT), are unknown. Understanding the metabolic effects of surgical menopause will inform clinical care. OBJECTIVE: To prospectively measure weight and body composition over 24 months following surgical menopause compared with a similar comparison group who retained their ovaries. METHODS: Prospective observational study of weight change from baseline to 24 months in 95 premenopausal women at elevated risk of ovarian cancer planning risk-reducing salpingo-oophorectomy (RRSO) and 99 comparators who retained their ovaries. Change in body composition from baseline to 24 months was also assessed by dual-energy x-ray absorptiometry in a subgroup of 54 women who underwent RRSO and 81 comparators who retained their ovaries. In the subgroup, weight, fat mass, lean mass, and abdominal fat measures were compared between groups. RESULTS: At 24 months both groups had gained weight (RRSO 2760 ± 4860 g vs comparators 1620 ± 4540 g) with no difference between groups (mean difference 730 g; 95% CI 920 g to 2380 g; P = .383). In the body composition subgroup, there was no difference in weight between groups at 24 months (mean difference 944 g; 95% CI -1120 g to 2614 g; P = .431). RRSO women may have gained slightly more abdominal visceral adipose tissue (mean difference 99.0 g; 95% CI 8.8 g to 189.2 g; P = .032) but there were no other differences in body composition. There were also no differences in weight or body composition between HRT users and nonusers at 24 months. CONCLUSION: 24 months after RRSO, there was no difference in body weight compared with women who retained their ovaries. RRSO women gained more abdominal visceral adipose tissue than comparators, but there were no other differences in body composition. Use of HRT following RRSO had no effect on these outcomes.


Assuntos
Neoplasias Ovarianas , Salpingo-Ooforectomia , Feminino , Humanos , Estudos Prospectivos , Menopausa , Terapia de Reposição Hormonal , Peso Corporal , Ovariectomia
9.
ACS Nano ; 17(10): 9025-9038, 2023 05 23.
Artigo em Inglês | MEDLINE | ID: mdl-37134316

RESUMO

The highly aligned extracellular matrix of metastatic breast cancer cells is considered to be the "highway" of cancer invasion, which strongly promotes the directional migration of cancer cells to break through the basement membrane. However, how the reorganized extracellular matrix regulates cancer cell migration remains unknown. Here, a single exposure of a femtosecond Airy beam followed by a capillary-assisted self-assembly process was used to fabricate a microclaw-array, which was used to mimic the highly oriented extracellular matrix of tumor cells and the pores in the matrix or basement membrane during cell invasion. Through the experiment, we found that metastatic breast cancer MDA-MB-231 cells and normal breast epithelial MCF-10A cells exhibit three major migration phenotypes on microclaw-array assembled with different lateral spacings: guidance, impasse, and penetration, whereas guided and penetrating migration are almost completely arrested in noninvasive MCF-7 cells. In addition, different mammary breast epithelial cells differ in their ability to spontaneously perceive and respond to the topology of the extracellular matrix at the subcellular and molecular levels, which ultimately affects the cell migratory phenotype and pathfinding. Altogether, we fabricated a microclaw-array as a flexible and high-throughput tool to mimic the extracellular matrix during invasion to study the migratory plasticity of cancer cells.


Assuntos
Neoplasias da Mama , Células Epiteliais , Humanos , Feminino , Células MCF-7 , Células Epiteliais/metabolismo , Fenótipo , Carmustina/metabolismo , Movimento Celular/fisiologia , Neoplasias da Mama/patologia , Linhagem Celular Tumoral , Invasividade Neoplásica
10.
Aging Dis ; 14(6): 2113-2126, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-37199584

RESUMO

Interleukin-(IL)-11 is a cytokine involved in hematopoiesis, cancer metastasis, and inflammation. IL-11 belongs to the IL-6 cytokine family, binding to the complex of receptors glycoprotein gp130 and the ligand-specific-receptor subunits (IL-11Rα or their soluble counterpart sIL-11R). IL-11/IL-11R signaling enhances osteoblast differentiation and bone formation and mitigates osteoclast-induced bone resorption and cancer bone metastasis. Recent studies have shown that systemic and osteoblast/osteocyte-specific IL-11 deficiency leads to reduced bone mass and formation, but also adiposity, glucose intolerance, and insulin resistance. In humans, mutations of IL-11 and the receptor IL-11RA genes are associated with height reduction, osteoarthritis, and craniosynostosis. In this review, we describe the emerging role of IL-11/IL-11R signaling in bone metabolism by targeting osteoblasts, osteoclasts, osteocytes, and bone mineralization. Furthermore, IL-11 promotes osteogenesis and suppresses adipogenesis, thereby influencing the fate of osteoblast/adipocyte differentiation derived from pluripotent mesenchymal stem cells. We have newly identified IL-11 as a bone-derived cytokine that regulates bone metabolism and the link between bone and other organs. Thus, IL-11 is vital in bone homeostasis and could be considered a potential therapeutic strategy.

11.
Soft Matter ; 19(17): 3222-3227, 2023 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-37083022

RESUMO

Active particles without detailed balance can rectify their random motions to drive the directed movement or rotation of asymmetric passive obstacles. However, whether they can drive the directed movement of symmetric passive obstacles is still unclear. Here, we show that a rod-like passive particle which is fixed to move along the x-axis in an active bath can keep long-lived directed movement at nearly constant speed due to the spontaneous symmetry breaking of the neighboring active particle cluster. If the passive particle is further confined by a harmonic potential, it may undergo self-sustained periodic oscillation for an appropriate length of the passive particle and self-propelled velocity of active particles. The restoring force from the harmonic potential will trigger the velocity jump-off and thus lead to self-sustained periodic oscillation. Remarkably, the relationship between the velocity of the passive particle and the external force shows that the effective viscosity of the active bath may become negative in some regime. Finally, we develop a minimum 1D theoretical model to further probe the mechanism underlying the directed movement and self-sustained oscillation of the passive particle. Our findings reveal the effect of the moving boundary on the active bath and demonstrate a novel method to extract practical mechanical work from the active bath to propel microdevices.

12.
Clin Nucl Med ; 48(1): 61-63, 2023 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-36469061

RESUMO

ABSTRACT: A 65-year-old man presented with abdominal bloating for approximately 4 weeks. After CT imaging, it was diagnosed as gastric carcinoma with hepatic metastasis. 68Ga-FAPI-04 PET/CT revealed much higher tumor-to-background contrast and more metastatic lesions compared with 18F-FDG PET/CT in this case. Following gastroscopy and pathological examination, the final diagnosis was malignant gastrointestinal stromal tumor. This case demonstrated that 68Ga-FAPI-04 PET/CT was more sensitive than 18F-FDG PET/CT for detecting primary and metastatic lesions in malignant gastrointestinal stromal tumor.


Assuntos
Tumores do Estroma Gastrointestinal , Tomografia por Emissão de Pósitrons combinada à Tomografia Computadorizada , Masculino , Humanos , Idoso , Tumores do Estroma Gastrointestinal/diagnóstico por imagem , Fluordesoxiglucose F18 , Tomografia por Emissão de Pósitrons
13.
Biophys J ; 121(23): 4740-4747, 2022 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-36116008

RESUMO

Touch allows us to gather abundant information in the world around us. However, how sensory cells embedded in the fingers convey texture information into their firing patterns is still poorly understood. Here, we develop an electromechanical model for roughness perception by incorporating main ingredients such as voltage-gated ion channels, active ion pumps, mechanosensitive channels, and cell deformation. The model reveals that sensory cells can convey texture wavelengths into the period of their firing patterns as the finger slides across object surfaces, but they can only convey a limited range of texture wavelengths. We also show that an increase in sliding speed broadens the decoding wavelength range at the cost of reduction of lower perception limits. Thus, a smaller sliding speed and a bigger contact force may be needed to successfully discern a smooth surface, consistent with previous psychophysical observations. Moreover, we show that cells with slowly adapting mechanosensitive channels can still fire action potentials under static loadings, indicating that slowly adapting mechanosensitive channels may contribute to the perception of coarse textures under static touch. Our work thus provides a new theoretical framework to study roughness perception and may have important implications for the design of electronic skin, artificial touch, and haptic interfaces.


Assuntos
Percepção
14.
ACS Appl Mater Interfaces ; 14(37): 42504-42512, 2022 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-36084147

RESUMO

Biological materials such as conch shells with crossed-lamellar textures hold impressive mechanical properties due to their capability to realize effective crack control and energy dissipation through the structural synergy of interfacial modulus mismatch and lamellar orientation disparity. Integrating this mechanism with mechanical metamaterial design can not only avoid the catastrophic post-yield stress drop found in traditional architectural materials with uniform lattice structures but also effectively maintain the stress level and improve the energy absorption ability. Herein, a novel bioinspired design strategy that combines regional particularity and overall cyclicity is proposed to innovate the connotation of long-range periodicity inside the metamaterial, in which the node constraint gradient and crossed-lamellar struts corresponding to the core features of conch shells are able to guide the deformation sequence with a self-strengthening response during compression. Detailed in situ experiments and finite element analysis confirm that the rotated broad layer stacking can shorten and impede the shear bands, further transforming the deformation of bioinspired metamaterial into a progressive, hierarchical way, highlighted by the cross-layer hysteresis. Even based on a brittle polymeric resin, excellent specific energy absorption capacity [4544 kJ/kg] has been achieved in this architecture, which far exceeds the reported metal-based syntactic foams for two orders of magnitude. These results offer new opportunities for the bioinspired metamaterials to substitute the widespread syntactic foams in specific applications required for both lightweight and energy absorption.


Assuntos
Polímeros , Impressão Tridimensional , Próteses e Implantes
15.
Stem Cells Int ; 2022: 4197473, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36132169

RESUMO

Purpose: Adipose-derived mesenchymal stem cells (ADSCs) are increasingly applied in tendon repair. However, the underlying mechanisms of ADSC-derived extracellular vesicles (EVs) in tendon healing are largely unknown. In this study, we investigated the effect of the EVs secreted by ADSCs on the recovery of tendon injuries and its potential mechanism. Materials and Methods: We injected ADSCs into the injured tendon, followed by the evaluation of the tissue morphology, tenocyte proliferation, and oxidative stress. Then, the injured tenocytes were treated with EVs secreted by ADSCs, and oxidative stress and proliferation of tenocytes in vitro were detected. After the overexpression and knockdown of miR-19a and its target protein IGFBP3, the oxidative stress and proliferation of tenocytes in vitro were assessed. Finally, the injured tendon was treated with EVs, and the tissue morphology and proliferation of the injured tendon in vivo were examined. Results: ADSC-derived EVs were found to inhibit oxidative stress and promote proliferation of tenocytes isolated from an injury model of rats. EVs were shown to carry miR-19a which regulated the expression of IGFBP3 through binding to 3'UTR of IGFBP3 mRNA. In addition, IGFBP3 promotes oxidative stress and inhibits proliferation of tenocytes. Finally, we found that ADSC-derived EVs promoted tendon wound healing in vivo. Conclusions: Our data suggest that treatment with ADSC-derived EVs ameliorates tendon injury by inhibiting oxidative stress and promoting proliferation in tenocytes. miR-19a carried by ADSC-derived EVs regulates IGFBP3 expression through binding to its 3'UTR.

16.
Biophys J ; 121(9): 1610-1618, 2022 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-35395246

RESUMO

Oscillations and waves are ubiquitous in living cellular systems. Generations of these spatiotemporal patterns are generally attributed to some mechanochemical feedbacks. Here, we treat cells as open systems, i.e., water and ions can pass through the cell membrane passively or actively, and reveal a new origin of wave generation. We show that osmotic shocks above a shock threshold will trigger self-sustained cell oscillations and result in long-range waves propagating without decrement, a phenomenon that is analogous to the excitable medium. The traveling wave propagates along the intercellular osmotic pressure gradient, and its wave speed scales with the magnitude of intercellular water flows. Furthermore, we also find that the traveling wave exhibits several hallmarks of solitary waves. Together, our findings predict a new mechanism of wave generation in living multicellular systems. The ubiquity of intercellular water exchanges implies that this mechanism may be relevant to a broad class of systems.


Assuntos
Água
17.
Lab Chip ; 22(8): 1556-1564, 2022 04 12.
Artigo em Inglês | MEDLINE | ID: mdl-35352749

RESUMO

High portability and miniaturization are two of the most important objectives pursued by microfluidic methods. However, there remain many challenges for the design of portable and visual microfluidic devices (e.g., electrokinetic experiments) due to the use of a microscope and power supply. To this end, we report a visual portable microfluidic experimental device (PMED) with multiple electric field regulation functions, which can realize the electric field regulation functions of various basic microfluidic experiments through modular design. The internal reaction process of the microfluidic chip is displayed by a smartphone, and the experimental results are analyzed using a mobile phone application (APP). Taking the induced-charge electroosmosis (ICEO) particle focusing phenomenon as an example, we carried out detailed experiments on PMED and obtained conclusions consistent with numerical simulations. In addition to ICEO experiments, other functions such as alternating electroosmosis (ACEO), thermal buoyancy convection, and dielectrophoresis (DEP) can be realized by replacing module-specific covers. The device expands the application of microfluidic experiments and provides a certain reference for the further integration and portability of subsequent microfluidic experiment devices.


Assuntos
Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas , Eletro-Osmose , Eletroforese , Microfluídica/métodos
18.
Phys Rev E ; 105(2-2): 025102, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35291076

RESUMO

We report a unique phenomenon in which liquid metal droplets (LMDs) under a pure ac electric field pump fluid. Unlike the directional pumping that occurs upon reversing the electric field polarity under a dc signal, this phenomenon allows the direction of fluid motion to be switched by simply shifting the position of the LMD within the cylindrical chamber. The physical mechanism behind this phenomenon has been termed Marangoni flow, caused by nonlinear electrocapillary stress. Under the influence of a localized, asymmetric ac electric field, the polarizable surface of the position-offset LMD produces a net time-averaged interfacial tension gradient that scales with twice the field strength, and thus pumps fluid unidirectionally. However, the traditional linear RC circuit polarization model of the LMD/electrolyte interface fails to capture the correct pump-flow direction when the thickness of the LMD oxide skin is non-negligible compared to the Debye length. Therefore, we developed a physical description by treating the oxide layer as a distributed capacitance with variable thickness and connected with the electric double layer. The flow profile is visualized via microparticle imaging velocimetry, and excellent consistency is found with simulation results obtained from the proposed nonlinear model. Furthermore, we investigate the effects of relevant parameters on fluid pumping and discuss a special phenomenon that does not exist in dc control systems. To our knowledge, no previous work addresses LMDs in this manner and uses a zero-mean ac electric field to achieve stable, adjustable directional pumping of a low-conductivity solution.

19.
Micromachines (Basel) ; 13(2)2022 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-35208356

RESUMO

With the development of industry IoT, microprocessors and sensors are widely used for autonomously transferring information to cyber-physics systems. Massive quantities and huge power consumption of the devices result in a severe increment of the chemical batteries, which is highly associated with problems, including environmental pollution, waste of human/financial resources, difficulty in replacement, etc. Driven by this issue, mechanical energy harvesting technology has been widely studied in the last few years as a great potential solution for battery substitution. Therefore, the piezoelectric generator is characterized as an efficient transformer from ambient vibration into electricity. In this paper, a spoke-like piezoelectric energy harvester is designed and fabricated with detailed introductions on the structure, materials, and fabrication. Focusing on improving the output efficiency and broadening the pulse width, on the one hand, the energy harvesting circuit is optimized by adding voltage monitoring and regulator modules. On the other hand, magnetic mass is adopted to employ the magnetic field of repulsive and upper repulsion-lower attraction mode. The spoke-like piezoelectric energy harvester suggests broadening the frequency domain and increasing the output performance, which is prepared for wireless sensors and portable electronics in remote areas and harsh environments.

20.
Micromachines (Basel) ; 13(2)2022 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-35208405

RESUMO

In recent years, low-power wireless sensors with high flexibility, portability and computing capability have been extensively applied in areas such as military, medicine and mechanical equipment condition monitoring. In this paper, a novel symmetrical T-shaped trapezoidal micro piezoelectric energy harvester (STTM-PEH) is proposed to supply energy for wireless sensors monitoring the vibrations of mechanical equipment. Firstly, the finite element model (FEM) of the STTM-PEH is established. Secondly, the modal analysis of the T-shaped trapezoidal piezoelectric cantilever beam is carried out by finite element software and its vibration modes are obtained. Additionally, the structural characteristics of the STTM-PEH and the composition of piezoelectric patches are described. Furthermore, the effects of resistance, acceleration coefficient, substrate materials and structural parameters of the output performance of the STTM-PEH are researched. The results indicate that the output power of the STTM-PEH rises first and then falls with a change in resistance, while the output voltage does not increase as resistance increases to a certain extent. Meanwhile, selecting copper as the piezoelectric material of the T-shaped trapezoidal piezoelectric cantilever beam can generate a higher energy output. Finally, how the structural parameters, including piezoelectric patch thickness, substrate thickness and cantilever head length, affect the output performance of the STTM-PEH is studied, which illustrates that the load range of the STTM-PEH can be appropriately broadened by adjusting the length of the cantilever beam head. This research is valuable for designing a novel high performance piezoelectric energy harvester.

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