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1.
Nat Commun ; 15(1): 4684, 2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38824184

RESUMO

Miniaturized passive fliers based on smart materials face challenges in precise control of shape-morphing for aerodynamics and contactless modulation of diverse gliding modes. Here, we present the optical control of gliding performances in azobenzene-crosslinked liquid crystal networks films through photochemical actuation, enabling reversible and bistable shape-morphing. First, an actuator film is integrated with additive constructs to form a rotating glider, inspired by the natural maple samara, surpassing natural counterparts in reversibly optical tuning of terminal velocity, rotational rate, and circling position. We demonstrate optical modulation dispersion of landing points for the photo-responsive microfliers indoors and outdoors. Secondly, we show the scalability of polymer film geometry for miniature gliders with similar light tunability. Thirdly, we extend the material platform to other three gliding modes: Javan cucumber seed-like glider, parachute and artificial dandelion seed. The findings pave the way for distributed microflier with contactless flight dynamics control.

2.
Toxicon ; 244: 107772, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38768828

RESUMO

Around 95% of snake venom is protein. Along with the soluble proteins, snake venom also contains proteins encapsulated in vesicles known as Snake Venom Extracellular Vesicles (SVEV). SVEVs are nano-sized membrane-bound vesicles released from the snake venom gland cells. The available published research works on SVEVs are minimal. Extracellular vesicles in the Snake Venom gland were initially discovered during the histopathological analysis of the Crotalus durissus terrificus snakes' venom gland. Later, various techniques were employed to isolate and characterize the SVEVs. The cargo of SVEV consists of a variety of proteins like Phospholipase A-2, C-type Lectins, L-Amino Acid Oxidase, Cysteine-Rich Secretory Proteins, Serine Proteinases, Dipeptidyl Peptidase-IV, Aminopeptidase-A, Ecto-5'-nucleotidases, Disintegrins. Proteomic data revealed the presence of some exclusive proteins in the SVEVs, and the other proteins are in varying concentrations in the SVEVs compared to their whole Venom. Interaction of SVEVs with mammalian cell lines showed the disruption of primary physiological functions leads to host immune modulation, and long-term effects of envenoming. Snakebite victim's blood showed variations in the specific Extracellular vesicle concentration. It has been hypothesized that SVEVs are responsible for long-term toxicity. The current review focuses on the various techniques adopted to isolate and characterize SVEVs and discusses the exclusiveness and variations of SVEV proteins and their role in snakebites.


Assuntos
Vesículas Extracelulares , Venenos de Serpentes , Vesículas Extracelulares/metabolismo , Animais , Proteômica , Crotalus
3.
Soft Matter ; 20(3): 511-522, 2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-38113054

RESUMO

Exploiting the interplay of anisotropic diamagnetic susceptibility of liquid crystalline monomers and site selective photopolymerization enables the fabrication of 3D freeforms with highly refined microstructures. Utilizing chain transfer agents in the mesogenic inks presents a pathway for broadly tuning the mechanical properties of liquid crystalline polymers and their response to stimuli. In particular, the combination of 1,4-benzenedimethanethiol and tetrabromomethane is shown to enable voxelated blueprinting of molecular order, while allowing for a modulation of the crosslink density and the mechanical properties. The formulation of these monomers allows for the resolution of the voxels to approach the limits set by the coherence lengths defined by the anchoring from surfaces. These compositions demonstrate the expected thermotropic responses while allowing for their functionalization with photochromic switches to elicit photomechanical responses. Actuation strains are shown to outstrip that accomplished with prior systems that did not access chain transfer agents to modulate the structure of the macromolecular network. Test cases of this system are shown to create freeform actuators that exploit the refined director patterns during high-resolution printing. These include topological defects, hierarchically-structured light responsive grippers, and biomimetic flyers whose flight dynamics can be actively modulated via irradiation with light.

4.
Soft Matter ; 19(45): 8764-8778, 2023 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-37938345

RESUMO

Liquid crystalline elastomers (LCEs) are active materials that are of interest due to their programmable response to various external stimuli such as light and heat. When exposed to these stimuli, the anisotropy in the response of the material is governed by the nematic director, which is a continuum parameter that is defined as the average local orientation of the mesogens in the liquid crystal phase. This nematic director can be programmed to be heterogeneous in space, creating a vast design space that is useful for applications ranging from artificial ligaments to deployable structures to self-assembling mechanisms. Even when specialized to long and thin strips of LCEs - the focus of this work - the vast design space has required the use of numerical simulations to aid in experimental discovery. To mitigate the computational expense of full 3-d numerical simulations, several dimensionally-reduced rod and ribbon models have been developed for LCE strips, but these have not accounted for the possibility of initial transverse curvature, like carpenter's tape spring. Motivated by recent experiments showing that transversely-curved LCE strips display a rich variety of configurations, this work derives a dimensionally-reduced 1-d model for pre-curved LCE strips. The 1-d model is validated against full 3-d finite element calculations, and it is also shown to capture experimental observations, including tape-spring-like localizations, in activated LCE strips.

5.
Acta Crystallogr E Crystallogr Commun ; 79(Pt 6): 538-544, 2023 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-37288464

RESUMO

The title Schiff base compounds, C22H26N4O (I) and C18H16FN3O (II), were each synthesized by a single-step condensation reaction. The substituted benzyl-idene ring is inclined to the pyrazole ring mean planes by 22.92 (7)° in I and 12.70 (9)° in II. The phenyl ring of the 4-amino-anti-pyrine unit is inclined to the pyrazole ring mean plane by 54.87 (7)° in I and by 60.44 (8)° in II. In the crystal of I, the mol-ecules are linked by C-H⋯O hydrogen bonds and C-H⋯π inter-actions to form layers lying parallel to (001). In the crystal of II, the mol-ecules are linked by C-H⋯O and C-H⋯F hydrogen bonds and C-H⋯π inter-actions, thereby forming layers lying parallel to (010). Hirshfeld surface analysis was employed to further qu-antify the inter-atomic inter-actions in the crystals of both compounds.

6.
J Forensic Leg Med ; 97: 102548, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37327568

RESUMO

The Acute Physiology and Chronic Health Evaluation II (APACHE II) scoring system is utilised as a prognostic method in paraquat poisoning; however, current evidence shows ambiguity. Although some studies have shown APACHE II to be a superior tool, others have reported it inferior to other prognostic markers, such as lactate, severity index of paraquat poisoning and urine paraquat concentration. Hence, to address this ambiguity, we conducted a systematic review and meta-analysis to analyse prognostic accuracy of APACHE II score in predicting mortality in paraquat poisoning. We included twenty studies with 2524 paraquat poisoned patients in the systematic review, after a comprehensive literature search in databases PubMed, Embase, Web of Science, Scopus and Cochrane Library, from which 16 studies were included in the meta-analysis. The survivors of paraquat poisoning were found to have significantly lower APACHE II scores (Mean Difference (MD): -5.76; 95% CI: -7.93 to -3.60 p < 0.0001; n = 16 studies) compared to non-survivors. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR) and diagnostic odds ratio (DOR) for APACHE II score <9 was found to be 74%, 68%, 2.58, 0.38 and 7.10, respectively (n = 5 studies). The area under the curve (AUC) of the bivariate summary receiver operating characteristic (SROC) curve was found to be 0.80. The pooled sensitivity, specificity, PLR, NLR and DOR for APACHE II score ≥9 was found to be 73%, 86%, 4.69, 0.33 and 16.42, respectively (n = 9 studies). The AUC of the SROC curve was found to be 0.89. Pairwise AUC comparison of APACHE II with other prognostic markers showed serum presepsin to have a significantly better discriminatory ability than APACHE II. Through the findings of this study, we conclude that APACHE II was found to be a good indicator of death in paraquat poisoning patients. However, higher APACHE II scores (≥9) depicted greater specificity in predicting mortality in paraquat poisoning. Thus, APACHE II can be used as a practical tool in the hand of physicians to prognose patients with paraquat poisoning to aid clinical decisions.


Assuntos
Ácido Láctico , Paraquat , Humanos , APACHE , Prognóstico , Curva ROC , Estudos Retrospectivos , Fragmentos de Peptídeos , Receptores de Lipopolissacarídeos
7.
Chemosphere ; 311(Pt 2): 137030, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36334741

RESUMO

Ternary nanohybrids based on mesoporous graphitic carbon nitride (g-C3N4) were synthesized and presented for developing stable and efficient Hydrogen (H2) production system. Based on photocatalytic activity, optimization was performed in three different stages to develop carbon nanotubes (CNTs) and WO3 loaded g-C3N4 (CWG-3). Initially, the effect of exfoliation was investigated, and a maximum specific surface area of 100.77 m2/g was achieved. 2D-2D interface between WO3 and g-C3N4 was targeted and achieved, to construct a highly efficient direct Z-scheme heterojunction. Optimized binary composite holds the enhanced activity of about 2.6 folds of H2 generation rates than the thermally exfoliated g-C3N4. Further, CNT loading towards binary composite in an optimized weight ratio enhances the activity by 6.86 folds than the pristine g-C3N4. Notably, optimized ternary nanohybrid generates 15,918 µmol h-1. g-1cat of molecular H2, under natural solar light irradiation with 5 vol% TEOA as a sacrificial agent. Constructive enhancements deliver remarkable H2 production and dye degradation activities. Results evident that, the same system can be useful for pilot-scale energy generation and other photocatalytic applications as well.

8.
Oncol Res ; 32(1): 73-94, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38188673

RESUMO

Exosomes, small tiny vesicle contains a large number of intracellular particles that employ to cause various diseases and prevent several pathological events as well in the human body. It is considered a "double-edged sword", and depending on its biological source, the action of exosomes varies under physiological conditions. Also, the isolation and characterization of the exosomes should be performed accurately and the methodology also will vary depending on the exosome source. Moreover, the uptake of exosomes from the recipients' cells is a vital and initial step for all the physiological actions. There are different mechanisms present in the exosomes' cellular uptake to deliver their cargo to acceptor cells. Once the exosomal uptake takes place, it releases the intracellular particles that leads to activate the physiological response. Even though exosomes have lavish functions, there are some challenges associated with every step of their preparation to bring potential therapeutic efficacy. So, overcoming the pitfalls would give a desired quantity of exosomes with high purity.


Assuntos
Exossomos , Neoplasias , Humanos
9.
Cryo Letters ; 44(6): 360-368, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38311930

RESUMO

BACKGROUND: Cicer microphyllum Benth. is a crop wild relative (CWR) of chickpea (C. arietinum L.), that possess useful genes for cold and drought tolerance. The species is being conserved in the In Vitro Active Genebank for short- to medium-term conservation. Cryopreservation would be a useful complementary approach for its long-term conservation. OBJECTIVE: The current work aimed to develop an efficient cryoconservation protocol for cryobanking of C. microphyllum shoot tips. MATERIALS AND METHODS: In vitro shoot tips excised from 4-month old shoot cultures grown on B5 + 0.5 mg/L KIN + 0.1 mg/L NAA + 10 mg/L AgNO3 medium were cryoconserved using a droplet-vitrification technique. Post-thaw regrowth was evaluated after: (i) preculture medium (B5 basal, B5 + 3, 4, 6 and 10% sucrose), (ii) preculture incubation temperature (25 ± 2, 10, 8 and 22/5 degree C), (iii) PVS2 duration (10, 20, 30. 40, 50 and 60 min) and (iv) regrowth medium (B5) supplemented with 0.5 mg/L KIN + 0.1 NAA mg/L; 0.5 mg/L KIN + 0.1 mg/L NAA + 10 mg/L AgNO3; 0.2 mg/L BAP + 10 mg/L AgNO3; 0.2 mg/L BAP + 20 mg/L AgNO3 and 0.2 mg/L BAP + 30 mg/L AgNO3. RESULTS: In vitro shoot tips grown on B5 + 0.5 mg/L KIN + 0.1 mg/L NAA + 10 mg/L AgNO3, precultured on B5 + 6% sucrose at 10 degree C for 3 days, followed by PVS2 treatment for 20 min, unloading solution for 60 min and regrowth on B5 + 0.2 mg/L BAP + 20 mg/L AgNO3 resulted in highest survival (57%) and regrowth (40%) after cryoconservation. CONCLUSION: The standardized protocol was successfully used for cryobanking of in vitro shoot tips of C. microphyllum in the In Vitro Base Genebank of ICAR-NBPGR, New Delhi. Doi.org/10.54680/fr23610110412.


Assuntos
Cicer , Criopreservação , Criopreservação/métodos , Cicer/genética , Crioprotetores/farmacologia , Brotos de Planta , Vitrificação , Sacarose
10.
J Indian Prosthodont Soc ; 22(1): 56-64, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36510948

RESUMO

Aim: The primary aim of this study is to analyse the stress distribution between an ALL ON FOUR implant supported prosthesis and the TREFOIL implant supported prosthesis with 3D finite element models. Settings and Design: An in vitro perspective. Materials and Methods: Two mandibular three-dimensional Finite Element Models were constructed by the CREO version 5 software, in which Model A depicts a mandible with ALL ON FOUR implant supported prost hesis and Model B will depict TREFOIL implant supported prosthesis. Model A contains four implants, two anterior straight and posterior tilted implants (30°), a bar and denture containing acrylic teeth. In Model B, it contains three straight implants and a prefabricated compensatory bar with standardised dimensions. To evaluate and compare the stress distribution between the bone and implant interface, one deleterious cantilever load of upto 300 N is applied on the second molar bilaterally and simultaneously. Another full bite biting load of 150 N is given bilaterally and simultaneously on the central groove of premolars and molars. Statistical Analysis Used: The results of the simulations obtained were analysed in terms of Von Mises equivalent stress levels at the bone -implant interface. Results: The results of loading 1 showed that the maximum Von Mises stress was recorded in the anterior implant region of the Trefoil system (Model B) when compared to All on four concept. The results of loading 2 showed that the maximum Von Mises stress were recorded in the anterior implant region Trefoil system (Model B) when compared to All on four concept. Conclusion: This invitro study concludes that All on Four implant supported prosthesis showed better stress distribution when compared to the Trefoil concept.


Assuntos
Implantes Dentários , Lotus , Análise de Elementos Finitos , Prótese Dentária Fixada por Implante , Análise do Estresse Dentário , Estresse Mecânico
11.
J Educ Health Promot ; 11: 160, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35847133

RESUMO

BACKGROUND: Conducting online classes and assessment during the COVID-19 pandemic is not without challenges. The world of medical education is adapting online training and assessment because of COVID-19 pandemic restrictions. The present study was conducted to assess the students' perception regarding the process, difficulties encountered and perceived effectiveness of online assessment. MATERIALS AND METHODS: Online viva-voce (theory and visual based) was conducted in a government medical college in Karwar, Karnataka, India using videoconferencing application (Google Meet) to 149 second MBBS students as a formative assessment in 2020 over 3 months. Ten students per day joined Google Meet, 10 questions were asked to each student and assessed using a tutor marking system (on-spot). A feedback questionnaire (Google Form) was administered to students who attended online Viva-Voce. Data was analysed using descriptive and inferential statistics (Student's t-test). RESULTS: Out of 149 students, 132 participated and responded to a feedback questionnaire. Majority of the participants (91%) agreed that questions covered all topics kept for viva, 82% of them felt it would be helpful for performance in final examinations. Thirty percent of students faced network issues at their places, 45% felt nervous while facing viva in the presence of other students and 35% of participants preferred online methods over traditional viva voce. Online viva voce can be transparent (90%) and less biased (88%) if done in structured format. CONCLUSION: Online viva-voce may become relevant and effective in medical education assessment with transparent marking system for students' performance.

12.
Bioinformation ; 18(1): 14-18, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35815197

RESUMO

Fluorosis is a metabolic disease that is endemic in nearly 25 countries with India being one of the most affected. It primarily affects the bone and the teeth. Moringa oleifera (MO) leaves are known to reduce the effect of fluorosis on various tissues. Therefore, it is of interest to document the effect of Moringa oleifera leaves on the hematological profile of fluorosis affected rats. Twenty four Sprague Dawley rats were housed two per cage in a room with 12 hours light and 12 hours dark cycle. The rats were allowed to adjust to the laboratory environment for about one to two weeks before the beginning of the study. This study reveals that MO leaves is effective in reducing the plasma fluoride content. It also helps in improving the Hb % and RBC count in fluorosis affected rats. Data shows that Moringa olifera leaves powder is effective in reducing the plasma fluoride content. It also helps in improving the Hemoglobin percentage & Red Blood Cell count in fluorosis affected rats.

13.
Sci Rep ; 12(1): 5150, 2022 03 25.
Artigo em Inglês | MEDLINE | ID: mdl-35338172

RESUMO

Vital sign monitoring systems are essential in the care of hospitalized neonates. Due to the immaturity of their organs and immune system, premature infants require continuous monitoring of their vital parameters and sensors need to be directly attached to their fragile skin. Besides mobility restrictions and stress, these sensors often cause skin irritation and may lead to pressure necrosis. In this work, we show that a contactless radar-based approach is viable for breathing monitoring in the Neonatal intensive care unit (NICU). For the first time, different scenarios common to the NICU daily routine are investigated, and the challenges of monitoring in a real clinical setup are addressed through different contributions in the signal processing framework. Rather than just discarding measurements under strong interference, we present a novel random body movement mitigation technique based on the time-frequency decomposition of the recovered signal. In addition, we propose a simple and accurate frequency estimator which explores the harmonic structure of the breathing signal. As a result, the proposed radar-based solution is able to provide reliable breathing frequency estimation, which is close to the reference cabled device values most of the time. Our findings shed light on the strengths and limitations of this technology and lay the foundation for future studies toward a completely contactless solution for vital signs monitoring.


Assuntos
Unidades de Terapia Intensiva Neonatal , Radar , Frequência Cardíaca , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Monitorização Fisiológica/métodos , Processamento de Sinais Assistido por Computador , Sinais Vitais
14.
Bioinformation ; 18(6): 501-505, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-37168795

RESUMO

Radiofrequency emitted radiations (RFEMR) from mobile phones are known to produce a stress response because of its effect on hypothalamus. Mobile phones have become an integral part of our lives with increasing usage not only in terms of number of users but also increase in talk time. Therefore, it is of interest to study the effect of mobile phone radiofrequency electromagnetic radiations on NSE and MDA levels in SD rats. Twelve male SD rats of 10-12weeks old, weighing 180-220 grams, were purchased from registered laboratory breeders & housed in a room with 12:12hour's light-dark cycle with adlibitum amount of food and RO water. Present study showed significant increase in NSE and MDA levels in rats exposed to RFEMR. This study proves that mobile RFEMR causes oxidative stress and oxidative damage in SD rats.

15.
Sci Total Environ ; 778: 146252, 2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-34030369

RESUMO

Surveillance of SARS-CoV-2 and organic tracers (OTs) were conducted in the community wastewater of Chennai city and the suburbs, South India, during partial and post lockdown phases (August-September 2020) as a response to the coronavirus disease 2019 (COVID-19) pandemic. Wastewater samples were collected from four sewage treatment plants (STPs), five sewage pumping stations (SPSs) and at different time intervals from a suburban hospital wastewater (HWW). Four different methods of wastewater concentrations viz., composite (COM), supernatant (SUP), sediment (SED), and syringe filtration (SYR) were subjected to quantitative real time-polymerase chain reaction (qRT-PCR). Unlike HWW, STP inlet, sludge and SPS samples were found with higher loading of SARS-CoV-2 by SED followed by SUP method. Given the higher levels of dissolved and suspended solids in STPs and SPSs over HWW, we suspect that this enveloped virus might exhibit the tendency of higher partitioning in solid phase. Cycle threshold (Ct) values were < 30 in 50% of the HWW samples indicating higher viral load from the COVID-19 infected patients. In the STP outlets, a strict decline of biochemical oxygen demand, >95% removal of caffeine, and absence of viral copies reflect the efficiency of the treatment plants in Chennai city. Among the detected OTs, a combination of maximum dynamic range and high concurrence percentage was observed for caffeine and N1 gene of SARS-CoV-2. Hence, we suggest that caffeine can be used as an indicator for the removal of SARS-CoV-2 by STPs. Our predicted estimated number of cases are in line with the available clinical data from the catchments. Densely distributed population of the Koyambedu catchment could be partly responsible for the high proportion of estimated infected individuals during the study period.


Assuntos
COVID-19 , SARS-CoV-2 , Cidades , Controle de Doenças Transmissíveis , Humanos , Índia , Águas Residuárias
16.
Plast Reconstr Surg Glob Open ; 9(4): e3428, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33912368

RESUMO

BACKGROUND: Plastic surgery varies in scope, especially in different settings. This study aimed to quantify the plastic surgery workforce in low-income countries (LICs), understand commonly treated conditions by plastic surgeons working in these settings, and assess the impact on reducing global disease burden. METHODS: We queried national and international surgery societies, plastic surgery societies, and non-governmental organizations to identify surgeons living and working in LICs who provide plastic surgical care using a cross-sectional survey. Respondents reported practice setting, training experience, income sources, and perceived barriers to care. Surgeons ranked commonly treated conditions and reported which of the Disease Control Priorities-3 essential surgery procedures they perform. RESULTS: An estimated 63 surgeons who consider themselves plastic surgeons were identified from 15 LICs, with no surgeons identified in the remaining 16 LICs. Responses were obtained from 43 surgeons (70.5%). The 3 most commonly reported conditions treated were burns, trauma, and cleft deformities. Of the 44 "Essential Surgical Package'' procedures, 37 were performed by respondents, with the most common being skin graft (73% of surgeons performing), cleft lip/palate repair (66%), and amputations/escharotomy (61%). The most commonly cited barrier to care was insufficient equipment. Only 9% and 5% of surgeons believed that there are enough plastic surgeons to handle the burden in their local region and country, respectively. CONCLUSIONS: Plastic surgery plays a significant role in the coverage of essential surgical conditions in LICs. Continued expansion of the plastic surgical workforce and accompanying infrastructure is critical to meet unmet surgical burden in low- and middle-income countries.

17.
J Burn Care Res ; 42(4): 621-626, 2021 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-33891676

RESUMO

In Nepal, preventable death and disability from burn injuries are common due to poor population-level spatial access to organized burn care. Most severe burns are referred to a single facility nationwide, often after suboptimal burn stabilization and/or significant care delay. Therefore, we aimed to identify existing first-level hospitals within Nepal that would optimize population-level access as "burn stabilization points" if their acute burn care capabilities are strengthened. A location-allocation model was created using designated first-level candidate hospitals, a population density grid for Nepal, and road network/travel speed data. Six models (A-F) were developed using cost-distance and network analyses in ArcGIS to identify the three vs five candidate hospitals at ≤2, 6, and 12 travel-hour thresholds that would optimize population-level spatial access. The baseline model demonstrated that currently 20.3% of the national population has access to organized burn care within 2 hours of travel, 37.2% within 6 travel-hours, and 72.6% within 12 travel-hours. If acute burn stabilization capabilities were strengthened, models A to C of three chosen hospitals would increase population-level burn care access to 45.2, 89.4, and 99.8% of the national population at ≤2, 6, and 12 travel-hours, respectively. In models D to F, five chosen hospitals would bring access to 53.4, 95.0, and 99.9% of the national population at ≤2, 6, and 12 travel-hours, respectively. These models demonstrate developing capabilities in three to five hospitals can provide population-level spatial access to acute burn care for most of Nepal's population. Organized efforts to increase burn stabilization points are feasible and imperative to reduce the rates of preventable burn-related death and disability country-wide.


Assuntos
Queimaduras/terapia , Fortalecimento Institucional/organização & administração , Cuidados Críticos/estatística & dados numéricos , Melhoria de Qualidade/organização & administração , Humanos , Modelos Organizacionais , Nepal , População Rural/estatística & dados numéricos , População Urbana/estatística & dados numéricos
18.
J Environ Manage ; 286: 112130, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33684804

RESUMO

Silver nanoparticles doped with FCNT-TiO2 heterogeneous catalyst was prepared via one-step chemical reduction process and their efficacy was tested for hydrogen production under solar simulator. Crystallinity, purity, optical properties, and morphologies of the catalysts were examined by X-Ray diffraction, Raman spectroscopy, UV-Visible diffuse reflectance spectra, and Transmission Electron Microscopy. The chemical states and interface interactions were studied by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The optimized catalyst showed 19.2 mmol g-1 h-1 of hydrogen production, which is 28.5 and 7 times higher than the pristine TiO2 nanoparticles and FCNT-TiO2 nanocomposite, respectively. The optimized catalyst showed stability up to 50 h under the solar simulator irradiation. The natural solar light irradiated catalyst showed ~2.2 times higher hydrogen production rate than the solar simulator irradiation. A plausible reaction mechanism of Ag NPs/FCNT-TiO2 photocatalyst was elucidated by investigating the beneficial co-catalytic role of Ag NPs and FCNTs for enhanced hydrogen production.


Assuntos
Nanopartículas Metálicas , Prata , Catálise , Hidrogênio , Luz , Titânio
19.
J Environ Manage ; 277: 111433, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33070019

RESUMO

In this research, efficient and novel catalysts based on hierarchical carbon nanohorns-titanium nanoflowers have been prepared by one-pot solvothermal process. Hydrogen generation from dye-contaminated water and dye degradation along with electrochemical supercapacitance performance have been investigated using the synthesized hierarchical catalyst to produce 4500 µmol g-1 h-1 of hydrogen from the photocatalytically generated aqueous methylene blue and methyl orange dyes, which were degraded up to 90% under natural solar light irradiation. These results offer a new path to generate hydrogen from the aqueous dyes. The catalysts electrode showed 164.6 F g-1 supercapacitance at 5 mV s-1 scan rate, which is nearly 1.3 and 1.65-times higher than that of pristine titanium nanoflower and carbon nanohorns electrodes, respectively. Such superior results were achieved due to good crystallinity, improved optical absorption strength, strong chemical composition between the two components, and hierarchical morphology as demonstrated from XRD, UV-DRS, TEM, XPS, and Raman spectral characterizations.


Assuntos
Carbono , Água , Catálise , Corantes , Hidrogênio , Titânio , Raios Ultravioleta
20.
Soft Matter ; 17(6): 1521-1529, 2021 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-33331368

RESUMO

The effect of chain extender structure and composition on the thermomechanical properties of liquid crystal elastomers (LCE) synthesized using thiol-acrylate Michael addition is presented. The intrinsic molecular stiffness of the thiol chain extender and its relative molar ratio to acrylate-based host mesogens determine the magnitudes of the thermomechanical strains, temperatures at which they are realized and the mechanical work-content. A non-linear structure-property relationship emerges, wherein higher concentrations of flexible extenders first magnify the thermomechanical sensitivity, but a continued increase leads to weaker actuation. Understanding this interplay leads to a composite material platform, enabling a peak specific work production of ∼2 J kg-1 using ∼115 mW of electrical power supplied at 2 V. Composites of LCE with eGaIn liquid metal (LM) are prepared, which act as heaters, while being capable of actuation themselves. The thermomechanically active electrodes convert the electrical power into Joule heat, which they efficiently couple with the neat LCE to which they are bound. This system harnesses the nascent responsiveness of the LCE using electrodes that work with them, instead of fighting against them (or passively standing in the way). Specific work generated increases when subjected to increasing levels of load, reaching a peak at loads ∼260× the actuator weight. These ideas are extended to tri-layered actuators, where LCE films with orthogonal molecular orientations sandwich LCE-LM composite heaters. Torsional actuation modes are harnessed to twist under load.

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