Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 39
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Soft Robot ; 2021 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-33416435

RESUMO

This study presents the design and test of a novel self-adaptive soft gripper, integrating pneumatic actuators and bistable carbon-fiber reinforced polymer laminates. The morphology was designed using the distinct structural characteristics of bistable structures; and the stable gripping configuration of the gripper was maintained through the bistability without continuous pressure application. The sufficient compliance of bistable structures makes the gripper versatile and adaptable to gripping deformable objects. First, a pneumatic-actuated method was introduced to achieve the reversible shape transition of the bistable structure. Next, three arrangement methods for actuators were analyzed with respect to the bistable transition and curvature, where it was found that the cross-arrangement is optimal. The effects of pneumatic actuators with different geometrical parameters on the response times are discussed, and the results show that the bistable structure can achieve shape transition within milliseconds under low pressure. Furthermore, the numerical and experimental results show good agreement between critical pressures and out-of-plane deformation. Furthermore, the shape retention function of the soft gripper was studied by using it to grasp objects of various sizes even when the pressure was reduced to the initial state. The bistable laminates exhibit sufficient compliance, and the deformed laminates can automatically accommodate the deformation of objects. The relationship between the weight and size of available gripping objects was studied; functional tests confirmed that the proposed soft gripper is versatile and adaptable for gripping objects of various shapes, sizes, and weights. This gripper has immense potential to reduce energy consumption in vacuum environments such as underwater and space.

2.
Vasc Endovascular Surg ; : 1538574420976237, 2020 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-33353495

RESUMO

Popliteal venous aneurysm (PVA) is defined as an increase in the diameter of the popliteal vein, twice its normal dimension. Herein, we report a case of right PVA with severe pulmonary embolism in a 75-year-old woman who presented with sudden chest tightness and dyspnea. Clinical examination revealed hypotension and hypoxemia. Radiographic investigations revealed extensive pulmonary embolism and right fusiform PVA. Following thrombolysis, her blood pressure and oxygen saturation normalized. However, she developed right calf swelling, and angiography revealed a thrombus in the right PVA, which was managed by catheter-directed thrombolysis. Thereafter, a vascular bypass was performed using the left great saphenous vein as a conduit to treat recurrent thrombosis. Subsequent venography indicated a patent vein graft, acceptable blood flow velocity, no thrombosis residue, and no significant thrombosis. Follow-ups at 3, 6, and 12 months revealed satisfactory outcomes. In conclusion, if the systemic condition is conducive, a surgical resection and reconstruction of the popliteal vein is recommended for the treatment of PVAs.

3.
Front Oncol ; 10: 575422, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33178604

RESUMO

Introduction: Prognosis prediction is essential to improve therapeutic strategies and to achieve better clinical outcomes in colorectal cancer (CRC) patients. Radiomics based on high-throughput mining of quantitative medical imaging is an emerging field in recent years. However, the relationship among prognosis, radiomics features, and gene expression remains unknown. Methods: We retrospectively analyzed 141 patients (from study 1) diagnosed with CRC from February 2018 to October 2019 and randomly divided them into training (N = 99) and testing (N = 42) cohorts. Radiomics features in venous phase image were extracted from preoperative computed tomography (CT) images. Gene expression was detected by RNA-sequencing on tumor tissues. The least absolute shrinkage and selection operator (LASSO) regression model was used for selecting imaging features and building the radiomics model. A total of 45 CRC patients (study 2) with immunohistochemical (IHC) staining of CXCL8 diagnosed with CRC from January 2014 to October 2018 were included in the independent testing cohort. A clinical model was validated for prognosis prediction in prognostic testing cohort (163 CRC patients from 2014 to 2018, study 3). We performed a combined radiomics model that was composed of radiomics score, tumor stage, and CXCL8-derived radiomics model to make comparison with the clinical model. Results: In our study, we identified the CXCL8 as a hub gene in affecting prognosis, which is mainly through regulating cytokine-cytokine receptor interaction and neutrophil migration pathway. The radiomics model incorporated 12 radiomics features screened by LASSO according to CXCL8 expression in the training cohort and showed good performance in testing and IHC testing cohorts. Finally, the CXCL8-derived radiomics model combined with tumor stage performed high ability in predicting the prognosis of CRC patients in the prognostic testing cohort, with an area under the curve (AUC) of 0.774 [95% confidence interval (CI): 0.674-0.874]. Kaplan-Meier analysis of the overall survival probability in CRC patients stratified by combined model revealed that high-risk patients have a poor prognosis compared with low-risk patients (Log-rank P < 0.0001). Conclusion: We demonstrated that the radiomics model reflected by CXCL8 combined with tumor stage information is a reliable approach to predict the prognosis in CRC patients and has a potential ability in assisting clinical decision-making.

4.
J Zhejiang Univ Sci B ; 21(10): 796-810, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33043645

RESUMO

Seed vigor is a key factor affecting seed quality. The mechanical drying process exerts a significant influence on rice seed vigor. The initial moisture content (IMC) and drying temperature are considered the main factors affecting rice seed vigor through mechanical drying. This study aimed to determine the optimum drying temperature for rice seeds according to the IMC, and elucidate the mechanisms mediating the effects of drying temperature and IMC on seed vigor. Rice seeds with three different IMCs (20%, 25%, and 30%) were dried to the target moisture content (14%) at four different drying temperatures. The results showed that the drying temperature and IMC had significant effects on the drying performance and vigor of the rice seeds. The upper limits of drying temperature for rice seeds with 20%, 25%, and 30% IMCs were 45, 42, and 38 °C, respectively. The drying rate and seed temperature increased significantly with increasing drying temperature. The drying temperature, drying rate, and seed temperature showed extremely significant negative correlations with germination energy (GE), germination rate, germination index (GI), and vigor index (VI). A high IMC and drying temperature probably induced a massive accumulation of hydrogen peroxide (H2O2) and superoxide anions in the seeds, enhanced superoxide dismutase (SOD) and catalase (CAT) activity, and increased the abscisic acid (ABA) content. In the early stage of seed germination, the IMC and drying temperature regulated seed germination through the metabolism of H2O2, gibberellin acid (GA), ABA, and α-amylase. These results indicate that the metabolism of reactive oxygen species (ROS), antioxidant enzymes, GA, ABA, and α-amylase might be involved in the mediation of the effects of drying temperature on seed vigor. The results of this study provide a theoretical basis and technical guidance for the mechanical drying of rice seeds.

5.
J Sci Food Agric ; 2020 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-32981065

RESUMO

BACKGROUND: Rice is an important food crop in China. Seed drying is an important step in the production of rice seeds. However, the regulatory mechanism of the effect of drying temperature on vigor of rice seeds with high initial moisture content (IMC) has not been examined. RESULTS: This study presents hot-air drying of rice seeds with high IMC (>30%) to assess the effect of drying temperature (35, 41, and 47 °C) on drying performance and seed vigor in terms of germination capacity. The results show a significant positive correlation between the drying rate, seed temperature, and drying temperature. High-temperature drying tends to cause a large accumulation of reactive oxygen species (ROS) and increases the activity of antioxidant enzymes in rice seeds. High-temperature drying also significantly increased abscisic acid (ABA) content and decreased gibberellin (GA) content through the regulation of the activity of metabolism related-enzymes. Moreover, changes in GA and ABA metabolism during early seed germination might be an important reason for the decrease in seed vigor with high-temperature drying. High-temperature drying also significantly inhibited the activity of α-amylase during early seed germination. CONCLUSION: A drying temperature of 35 °C was safe for rice seeds with high IMC, whereas higher drying temperatures (41 and 47 °C) reduced rice seed vigor remarkably. The metabolism of ROS, antioxidant enzymes, GA, ABA, and α-amylase might be closely involved in the regulation of the effect of drying temperature on the seed vigor of rice seeds with high IMC. The results of this study, therefore, provide a theoretical basis and technical guidance for mechanical drying of rice seeds. © 2020 Society of Chemical Industry.

6.
Biosens Bioelectron ; 168: 112569, 2020 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-32905930

RESUMO

Wearable and implantable bio-integrated electronics have started to gain momentum because of their essential role in improving the quality of life for various patients and healthy individuals. However, their continuous operation is often limited by traditional battery technologies with a limited lifespan, creating a significant challenge for their development. Thus, it is highly desirable to harvest biomechanical energies from human motion for self-powered bio-integrated functional devices. Piezoelectric energy harvesters are ideal candidates to achieve this goal by converting biomechanical energy to electric energy. Because of their applications on soft and highly deformable tissues of the human body, these devices also need to be mechanically flexible and stretchable, thus posing a significant challenge. Effective methods to address the challenge include the exploration of new stretchable piezoelectric materials (e.g., hybrid composite material) and stretchable structures (e.g., buckled shapes, serpentine mesh layouts, kirigami designs, among others). This review presents an overview of the recent developments in new intrinsically stretchable piezoelectric materials and rigid inorganic piezoelectric materials with novel stretchable structures for flexible and stretchable piezoelectric sensors and energy harvesters. Following the discussion of theoretical modeling of the piezoelectric materials to convert mechanical deformations into electrical signals, the representative applications of stretchable piezoelectric materials and structures in wearable and implantable devices are briefly summarized. The present limitations and future research directions of flexible and stretchable piezoelectric devices are then discussed.

7.
Nanotechnology ; 31(33): 335714, 2020 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-32365343

RESUMO

Large electromechanical response of ferroelectric materials is particularly appealing for applications in functional devices, such as sensors and actuators. For conventional ferroelectric materials, however, the mechanical strain under an external electric field, i.e. the electrostrain, is often limited by the intrinsic electromechanical property of the materials. Domain engineering has been suggested as a practical way to overcome this limitation and to enhance the electrostrain. Here, we show from phase-field simulations that reversible domain switching in ordered ferroelectric nanostructures with optimized geometric configurations can enhance the electrostrain significantly. In the presence of an external electric field, the domains in such nanostructures can switch from a multi-domain state confined by the geometric configurations to a mono-domain state. It is interesting that the domains can switch back to the multi-domain state due to strong internal depolarization fields once the electric field is removed. As a result, accompanying the reversible domain switching behavior, a large and reversible electrostrain can be obtained. Going further, it is found that the temperature dependence of the large electrostrain is similar to that of polarization in such nanostructures. The present work opens a perspective to obtaining large electrostrain in nanoscale ferroelectrics, which holds great promise for designing electromechanical functional devices with high performance.

8.
Polymers (Basel) ; 12(5)2020 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-32357439

RESUMO

The bistability of anti-symmetric thin shallow cylindrical polymer composite shells, made of carbon fiber/epoxy resin, has already been investigated based on the uniform curvature and inextensible deformation assumptions by researchers in detail. In this paper, a non-uniform curvature model that considers the extensible deformations is proposed. Furthermore, a parametric modeling and automatic postprocessing plug-in component for the bistability analysis of polymer composite cylindrical shells is established by means of ABAQUS-software, by which the equilibrium configurations and the load-displacement curves during the snap process can be easily obtained. The presented analytical model is validated by the numerical simulation and literature models, while the factors affecting the bistability of anti-symmetric cylindrical shells are revisited. In addition, the planform effects of anti-symmetric cylindrical shells with rectangular, elliptical and trapezoidal planform are discussed. The results show that the presented analytical model improves the accuracy of the prediction of the principal curvature of second equilibrium configuration and agree well with the numerical results.

9.
Zhongguo Dang Dai Er Ke Za Zhi ; 22(5): 419-424, 2020 May.
Artigo em Chinês | MEDLINE | ID: mdl-32434634

RESUMO

OBJECTIVE: To study the clinical features of coronavirus disease 2019 (COVID-19) in children aged <18 years. METHODS: A retrospective analysis was performed from the medical data of 23 children, aged from 3 months to 17 years and 8 months, who were diagnosed with COVID-19 in Jiangxi, China from January 21 to February 29, 2020. RESULTS: Of the 23 children with COVID-19, 17 had family aggregation. Three children (13%) had asymptomatic infection, 6 (26%) had mild type, and 14 (61%) had common type. Among these 23 children, 16 (70%) had fever, 11 (48%) had cough, 8 (35%) had fever and cough, and 8 (35%) had wet rales in the lungs. The period from disease onset or the first nucleic acid-positive detection of SARS-CoV-2 to the virus nucleic acid negative conversion was 6-24 days (median 12 days). Of the 23 children, 3 had a reduction in total leukocyte count, 2 had a reduction in lymphocytes, 2 had an increase in C-reactive protein, and 2 had an increase in D-dimer. Abnormal pulmonary CT findings were observed in 12 children, among whom 9 had patchy ground-glass opacities in both lungs. All 23 children received antiviral therapy and were recovered. CONCLUSIONS: COVID-19 in children aged <18 years often occurs with family aggregation, with no specific clinical manifestation and laboratory examination results. Most of these children have mild symptoms and a good prognosis. Epidemiological history is of particular importance in the diagnosis of COVID-19 in children aged <18 years.


Assuntos
Betacoronavirus , Infecções por Coronavirus , Pandemias , Pneumonia Viral , Adolescente , Criança , Pré-Escolar , China , Humanos , Lactente , Estudos Retrospectivos
10.
Mol Med Rep ; 21(4): 1739-1748, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32319617

RESUMO

Osteosarcoma (OS) is a primary malignant tumor that occurs in bone, and mainly affects children and adolescents. C­type lectin domain family 3 member A (CLEC3A) is a member of the C­type lectin superfamily, which regulates various biological functions of cells. The present study aimed to identify the effects and related mechanisms of CLEC3A in the proliferation and chemosensitivity of OS cells. The expression of CLEC3A in OS was analyzed using the Gene Expression Omnibus data profile GSE99671, and its expression in OS samples was verified using reverse transcription­quantitative PCR (RT­qPCR) and immunohistochemical staining. The relationship between the expression of CLEC3A and clinical traits in patients with OS was also analyzed, including age, tumor size, TNM stage and lymph node metastasis. Cell Counting Kit­8 assays, colony formation assays and cell cycle distribution analysis were used to determine the roles of CLEC3A in the proliferation and chemosensitivity of OS cells. Finally, RT­qPCR and western blotting were used to demonstrate the relationship between CLEC3A and the AKT1/mTOR/hypoxia­inducible factor 1­α (HIF1α) pathway. Both the mRNA and protein expression levels of CLEC3A were increased in OS tissues compared with adjacent non­tumor tissues, and this was positively associated with TNM stage and lymph node metastasis. The genetic knockdown of CLEC3A with small interfering RNA decreased OS cell proliferation and colony formation, and induced G1 phase arrest, whereas the overexpression of CLEC3A increased OS cell proliferation and colony formation, and alleviated G1 phase arrest. The suppression of CLEC3A also promoted enhanced the chemosensitivity of OS cells to doxorubicin (DOX) and cisplatin (CDDP); it also inhibited the expression of AKT1, mTOR and HIF1α, further to the nuclear localization of HIF1α, and HIF1α target gene expression levels, including VEGF, GLUT1 and MCL1 were also decreased. Furthermore, treatment with the AKT activator SC79 blocked the inhibitory effects of CLEC3A silencing in OS cells. In conclusion, these findings suggested that CLEC3A may function as an oncogene in OS, and that the suppression of CLEC3A may inhibit OS cell proliferation and promote chemosensitivity through the AKT1/mTOR/HIF1α signaling pathway.

11.
Int J Mol Med ; 45(5): 1317-1326, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32323741

RESUMO

Osteosarcoma is a common type of bone tumor that primarily occurs in children and young adults. MicroRNA (miRNA/miR) dysregulation is associated with the progression of osteosarcoma; therefore, the aim of the present study was to investigate the biological functions and molecular mechanisms of miR­145­5p in osteosarcoma. The expression of miR­145­5p in osteosarcoma tissues and cell lines was quantified using reverse transcription­quantitative PCR (RT­qPCR). The effect of miR­145­5p on the proliferation of osteosarcoma cells was detected using Cell Counting Kit­8 and colony formation assays, as well as cell cycle distribution analysis. The effect of miR­145­5p on tumor growth was further investigated in vivo using a subcutaneous tumor model in nude mice. The interaction between miR­145­5p and E2F transcription factor 3 (E2F3) was determined using bioinformatics analysis, a luciferase assay, RT­qPCR and western blotting. The results revealed that miR­145­5p expression was decreased in osteosarcoma cell lines and tissues compared with the corresponding normal controls. Increased miR­145­5p expression inhibited the proliferation and colony formation ability of osteosarcoma cells, and induced G1 phase arrest. Furthermore, mice injected with tumor cells overexpressing miR­145­5p exhibited smaller tumors than those in the control group. Further investigation revealed that miR­145­5p binds to and decreases the expression of E2F3. In addition, the mRNA levels of E2F3 were negatively associated with miR­145­5p in osteosarcoma tissues, and increasing E2F3 expression abrogated the inhibitory effects of miR­145­5p on osteosarcoma cells. Collectively, the results obtained in the present study suggest that miR­145­5p may suppress the progression of osteosarcoma, and may serve as a useful biomarker for the diagnosis of osteosarcoma, as well as a therapeutic target.

12.
Nanoscale ; 12(8): 5003-5013, 2020 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-32064473

RESUMO

Molybdenum disulfide (MoS2) can be an efficient electro-catalyst for the hydrogen evolution reaction (HER) as an alternative to precious metals, but significant efforts are still needed to further improve its efficiency. Among various approaches, the formation of edge aligned MoS2 on an electrically conductive support is highly promising for cost-effective H2 production. Nevertheless, catalysis is highly impeded by the poor charge transport between the electrode materials and also between the multilayers of MoS2. This research presents a strategy to improve the HER catalysis by binding layers of metallic molybdenum dioxide (MoO2) and MoS2 to form hybrid MoS2/MoO2 nanosheets (attached and cross-linked to each other). Taking advantage of the hybrid structure and the mechanical strength of the carbon cloth, a catalyst with outstanding catalytic performance in the HER is demonstrated. This work shows not only a strategy to efficiently improve the electrochemical process, but also the preparation of a highly efficient catalyst for constant and robust H2 production.

13.
ACS Nano ; 14(2): 2336-2344, 2020 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-31951370

RESUMO

Designing anisotropic architectures enables the creation of soft materials with rich properties and functions to artificially simulate the evolutionary diversity of biology. In the important liquid crystalline hybrid (LCH) hydrogels, free manipulation of liquid crystalline order in high accuracy and efficiency has been long pursued to design properties and functions but remains a challenge. Here, we realize digital programing LC order in graphene oxide LCH hydrogels in high size resolution (∼20 µm) and efficiency by using shearing microlithography. The localized shear-induced LC order organization is immobilized by cross-linking gelation, and we prepare graphene oxide LCH hydrogels with digital programmed patterns in a large area. The shearing order generates a vertical alignment of graphene oxide sheets in hydrogels and a considerable mechanical anisotropy controlled by the shearing angle and interval spacing. By diversely organizing geometry of LC order, the mechanical response behaviors of LCH hydrogels are designed to exhibit localized deformations, steered cracking, and programmable swelling actuations. Our work offers a versatile avenue to scalably digital program LCH hydrogels in a high efficiency and accuracy. The digital designed hydrogel promises wide uses in actuators, bioscaffolds, biomimetic materials, and soft designer materials.

14.
Langmuir ; 35(52): 17000-17008, 2019 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-31786923

RESUMO

A droplet that impacts on a superhydrophobic surface will undergo a process of unfolding, contracting, and finally rebounding from the surface. With regards to the pancake bouncing behavior of a droplet, since the retraction process of the droplet is omitted, the contact time is greatly shortened compared to the normal type of bouncing. However, the quantitative prediction to the range of droplet pancake bouncing and the adjustment of pancake bouncing state have yet to be probed into. In this paper, we reported the controllable pancake bouncing of droplets by adjusting the size of the superhydrophobic surface with microstructures. In addition, we also discovered a dimensional effect with regards to pancake bouncing, namely, the pancake bouncing would be more likely to happen on the surfaces with large post spacing for the droplet with the larger radius. The contact time could be reduced to 2 ms by adjusting the size of the microstructures and the radius of the droplets. Based on the relationship between the droplet bouncing state and the surface microstructure size, we are able to propose reasonable dimensions for the surfaces in order to control pancake bouncing.

15.
Nat Commun ; 10(1): 3951, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31477695

RESUMO

Ferroelastic switching in ferroelectric/multiferroic oxides plays a crucial role in determining their dielectric, piezoelectric, and magnetoelectric properties. In thin films of these materials, however, substrate clamping is generally thought to limit the electric-field- or mechanical-force-driven responses to the local scale. Here, we report mechanical-force-induced large-area, non-local, collective ferroelastic domain switching in PbTiO3 epitaxial thin films by tuning the misfit-strain to be near a phase boundary wherein c/a and a1/a2 nanodomains coexist. Phenomenological models suggest that the collective, c-a-c-a ferroelastic switching arises from the small potential barrier between the degenerate domain structures, and the large anisotropy of a and c domains, which collectively generates much larger response and large-area domain propagation. Large-area, non-local response under small stimuli, unlike traditional local response to external field, provides an opportunity of unique response to local stimuli, which has potential for use in high-sensitivity pressure sensors and switches.

16.
Seizure ; 71: 174-178, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31382136

RESUMO

PURPOSE: To compare the clinical efficacy of high-dose prednisone monotherapy and the combination of hormone and moderate-dose topiramate (TPM) therapy in children with infantile spasms (IS) and late-onset epileptic spasms (ES), and to evaluate whether the addition of TPM would provide more benefits for patients. METHODS: All patients were assigned to receive either high-dose prednisone alone (the maximum doses was 60 mg a day) or high-dose prednisone with TPM (the moderate doses was 5 mg/kg/day). The primary outcome was the proportion of children who achieved cessation of spasms at day-49 or day-56 after initial treatment (the minimum duration of treatment were 49 days). RESULTS: 77 patients were randomly divided into two groups. The control rate of spasms on day-14 in hormone monotherapy was similar to combination therapy (71.8% vs 76.3%, p = 0.796). The cessation of spasms rate of patients on day-49 or day-56 was also similar between the two groups (71.8% vs 65.8%, p = 0.569). After 4 months, the cessation of spasms rate of patients in the group of hormone monotherapy was higher than the group of combination therapy, but there was no significant difference (61.5% vs 50.0%, p = 0.308). CONCLUSION: The efficacy of the combination therapy was not better than that of the monotherapy in achieving spasm freedom at 14-days, 49-days or 56-days and day-120 in the patients. Adding-on moderate-dose TPM did not help more children achieve spasm freedom and provided no benefit for prevention of IS and late-onset ES in short term. Higher-dose regimens of TPM might be more effective.


Assuntos
Anticonvulsivantes/farmacologia , Glucocorticoides/farmacologia , Avaliação de Resultados em Cuidados de Saúde , Prednisona/farmacologia , Espasmos Infantis/tratamento farmacológico , Topiramato/farmacologia , Idade de Início , Anticonvulsivantes/administração & dosagem , Pré-Escolar , Quimioterapia Combinada , Feminino , Glucocorticoides/administração & dosagem , Humanos , Lactente , Masculino , Prednisona/administração & dosagem , Topiramato/administração & dosagem
17.
ACS Nano ; 13(7): 7930-7938, 2019 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-31241310

RESUMO

A nature-inspired water-cycling system, akin to trees, to perform effective water and solar energy management for photosynthesis and transpiration is considered to be a promising strategy to solve water scarcity issues globally. However, challenges remain in terms of the relatively low transport rate, short transport distance, and unsatisfactory extraction efficiency. Herein, enlightened by conifer tracheid construction, an efficient water transport and evaporation system composed of a hierarchical structured aerogel is reported. This architecture with radially aligned channels, micron pores, and molecular meshes is realized by applying a radial ice-template method and in situ cryopolymerization technique. This nature-inspired design benefits the aerogel excellent capillary rise performance, realizing a long-distance (>28 cm at 190 min) and quick (>1 cm at 1 s, >9 cm at 300 s) antigravity water transport on a macroscopic scale, regardless of clean water, seawater, sandy groundwater, or dye-including effluent. Furthermore, an efficient water transpiration and collection is performed by the bilayer-structured aerogel with a carbon heat collector on an aerogel top, demonstrating a solar steam generation rate of 2.0 kg m-2 h-1 with the energy conversion efficiency up to 85.7% under one solar illumination. This biomimetic design with the advantage of water transport and evaporation provides a potential approach to realize water purification, regeneration, and desalination.

18.
Langmuir ; 35(21): 6870-6877, 2019 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-31042869

RESUMO

The wetting behavior of hierarchically wrinkled surfaces has attracted great interest because of its broad application in flexible electronic, microfluidic chip, and biomedicine. However, theoretical studies concerning the relationship between the apparent contact angle and mechanical strain applied on the soft and flexible surface with a hierarchically wrinkled structure are still limited. We established a theoretical framework to describe and understand how prestrain and applied dynamic strain reversibly tune the wettability of the hierarchically wrinkled surface. More specifically, a direct relationship between the mechanical strain and contact angle was built through reversible tuning of the amplitude and the wavelength of the wrinkled structures caused by mechanical strain, which allowed for more precise adjustment of surface wettability. To verify the accuracy of the theoretical relationship between the contact angle and mechanical strain, a soft surface with a hierarchically wrinkled structure was prepared by combining wrinkled microstructures and strip ones. The results showed that the experimental contact angles were in agreement with the theoretical ones within a limited error range. This will be helpful for further investigation on the wettability of hierarchically wrinkled surfaces.

19.
Materials (Basel) ; 12(7)2019 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-30934906

RESUMO

Unidirectional transport is attracting increasing attention in the field of microfluidics, because it does not require an external energy supply. However, most of the current self-driving structures are still plagued with persistent problems that restrict their practical applications. These include low transport velocity, short transport distance, and complex structure. This work reports the design of a new arrowhead microstructure array, on which liquid transport can reach speeds of 23 mm/s and the ratio of transport length to channel width (L/R) can reach up to approximately 40. This structure drives liquid through a unique arrow conformation, which can induce capillary force and arrest the reverse motion of the liquid simultaneously. By means of theory, simulation, and experiment, we have studied the mechanism of liquid transport on this structure. We provide a detailed discussion of the relationship between the velocity of liquid transport and the microstructural dimensions. The findings may inspire the design of novel, unidirectional, liquid-spreading surfaces.

20.
Nanomaterials (Basel) ; 9(2)2019 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-30781651

RESUMO

Flexible electronic systems have received increasing attention in the past few decades because of their wide-ranging applications that include the flexible display, eyelike digital camera, skin electronics, and intelligent surgical gloves, among many other health monitoring devices. As one of the most widely used technologies to integrate rigid functional devices with elastomeric substrates for the manufacturing of flexible electronic devices, transfer printing technology has been extensively studied. Though primarily relying on reversible interfacial adhesion, a variety of advanced transfer printing methods have been proposed and demonstrated. In this review, we first summarize the characteristics of a few representative methods of transfer printing. Next, we will introduce successful demonstrations of each method in flexible electronic devices. Moreover, the potential challenges and future development opportunities for transfer printing will then be briefly discussed.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA