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1.
Chem Commun (Camb) ; 60(7): 827-830, 2024 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-38131208

RESUMO

This study showcases the design and development of a facile method for synthesizing trinitro-pyrazolo-triazole (TNPT) and its derivatives. The synthesized compounds are analysed using multinuclear NMR [1H, 13C, and 15N] and HRMS analyses. Furthermore, X-ray diffraction studies confirm the structure of some TNPT derivatives. Notably, compounds 8, 9, 11, and 12 exhibit good thermal stability with a decomposition threshold above 250 °C, and show a high level of insensitivity towards impact and friction [impact sensitivity (IS) is more than 25 J and friction sensitivity (FS) is above 180 N]. Compound 12, in particular, displays excellent performance characteristics [density 1.76 g cc-1 (at 298 K), a high detonation velocity (Dv = 8550 m s-1), and good thermal stability (Td = 280 °C), with high insensitivity towards impact and friction (IS = 35 J; FS = 180 N)]. The Hirshfeld surface analysis study provides further insight into the sensitivity of the TNPT derivatives.

2.
Biosensors (Basel) ; 13(8)2023 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-37622904

RESUMO

The detection of the lead heavy metal (Pb) in water is crucial in many chemical processes, as it is associated with serious health hazards. Here, we report the selective and precise colorimetric detection of Pb2+ ions in water, exploiting the aggregation and self-assembly mechanisms of glutathione (GSH)-functionalized gold nanoparticles (GNPs). The carboxyl functional groups are able to create coordination complexes with Pb2+, inducing aggregation amongst the GSH-GNPs in the presence of Pb2+ due to the chelation of the GSH ligands. The resulting aggregation amongst the GSH-GNPs in the presence of Pb2+ increases the aggregate size depending on the available Pb2+ ions, affecting the plasmonic coupling. This causes a substantial shift in the plasmon wavelength to a longer wavelength side with increasing Pb2+ concentration, resulting in a red-to-blue colorimetric or visual change, enabling the instant determination of lead content in water.


Assuntos
Colorimetria , Nanopartículas Metálicas , Ouro , Chumbo , Íons , Glutationa , Coloide de Ouro
3.
Transl Oncol ; 35: 101730, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37406550

RESUMO

Non-coding RNAs (ncRNAs) have emerged as key regulators of gene expression, with growing evidence implicating their involvement in cancer development and progression. The potential of ncRNAs as diagnostic and prognostic biomarkers for cancer is promising, with emphasis on their use in liquid biopsy and tissue-based diagnostics. In a nutshell, the review comprehensively summarizes the diverse classes of ncRNAs implicated in cancer, including microRNAs, long non-coding RNAs, and circular RNAs, and their functions and mechanisms of action. Furthermore, we describe the potential therapeutic applications of ncRNAs, including anti-miRNA oligonucleotides, siRNAs, and other RNA-based therapeutics in cancer treatment. However, significant challenges remain in developing effective ncRNA-based diagnostics and therapeutics, including the lack of specificity, limited understanding of mechanisms, and delivery challenges. This review also covers the current state-of-the-art non-coding RNA research technologies and bioinformatic analysis tools. Lastly, we outline future research directions in non-coding RNA research in cancer, including developing novel biomarkers, therapeutic targets, and modalities. In summary, this review provides a comprehensive understanding of non-coding RNAs in cancer and their potential clinical applications, highlighting both the opportunities and challenges in this rapidly evolving field.

4.
Curr Microbiol ; 78(12): 4072-4083, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34559288

RESUMO

Fe deficiency is a major challenge that limits agricultural productivity and is a serious human health concern worldwide. Under iron-limiting conditions soil microorganisms produce siderophores, that chelates Fe3+ (ferric) and make it available to the plants. Selection of efficient siderophore producing bacteria and establishing their role in enhancing iron uptake is a strategic approach for improving plant nutrition. Hence 3 efficient isolates Pantoea agglomerans, Pseudomonas plecoglossida and Lactococcus lactis, selected from a repository of 154 bacteria, producing catecholate, hydroxamate and carboxylate siderophores, respectively, were assessed for Fe chelation efficiency using 59Fe and their role in plant biometric parameters, Fe uptake and antioxidant enzymes with tomato (Strategy I) and wheat (Strategy II) test plants under hydroponic system. Cell-free siderophore preparation (Sid) improved plant parameters and iron nutrition more efficiently than bacterial inoculants. Pantoea agglomerans was proven best as its 59Fe-bound siderophore complex showed the highest uptake of 4.25 and 1.59 Bq plant-1 in wheat and tomato, respectively. Further, the Fe-starved plants (1 µm Fe-EDTA) showed around two-fold higher 59Fe uptake than those raised under Fe-sufficient condition (100 µm Fe-EDTA). Results indicated that probably the bacterial mediated iron translocation in plants is Strategy III, complementing both Strategy I and II by facilitating higher availability of chelated Fe to plant reductases directly and/or through ligand exchange with phytosiderophores, respectively. This study highlights the need for integration of siderophore based formulations in INM strategies for enhancing plant iron content to address the Fe deficiency challenge of the soil and human nutrition.


Assuntos
Sideróforos , Solanum lycopersicum , Bactérias , Humanos , Ferro , Solo
5.
Front Microbiol ; 12: 805498, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35360654

RESUMO

Interactions among the plant microbiome and its host are dynamic, both spatially and temporally, leading to beneficial or pathogenic relationships in the rhizosphere, phyllosphere, and endosphere. These interactions range from cellular to molecular and genomic levels, exemplified by many complementing and coevolutionary relationships. The host plants acquire many metabolic and developmental traits such as alteration in their exudation pattern, acquisition of systemic tolerance, and coordination of signaling metabolites to interact with the microbial partners including bacteria, fungi, archaea, protists, and viruses. The microbiome responds by gaining or losing its traits to various molecular signals from the host plants and the environment. Such adaptive traits in the host and microbial partners make way for their coexistence, living together on, around, or inside the plants. The beneficial plant microbiome interactions have been exploited using traditional culturable approaches by isolating microbes with target functions, clearly contributing toward the host plants' growth, fitness, and stress resilience. The new knowledge gained on the unculturable members of the plant microbiome using metagenome research has clearly indicated the predominance of particular phyla/genera with presumptive functions. Practically, the culturable approach gives beneficial microbes in hand for direct use, whereas the unculturable approach gives the perfect theoretical information about the taxonomy and metabolic potential of well-colonized major microbial groups associated with the plants. To capitalize on such beneficial, endemic, and functionally diverse microbiome, the strategic approach of concomitant use of culture-dependent and culture-independent techniques would help in designing novel "biologicals" for various crops. The designed biologicals (or bioinoculants) should ensure the community's persistence due to their genomic and functional abilities. Here, we discuss the current paradigm on plant-microbiome-induced adaptive functions for the host and the strategies for synthesizing novel bioinoculants based on functions or phylum predominance of microbial communities using culturable and unculturable approaches. The effective crop-specific inclusive microbial community bioinoculants may lead to reduction in the cost of cultivation and improvement in soil and plant health for sustainable agriculture.

6.
Curr Eye Res ; 46(1): 78-82, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32478613

RESUMO

Purpose: To describe a goats' eye training model for teaching of trabeculectomy and releasable suture techniques for Ophthalmology residents. Methods: A descriptive report explaining the methodology for setting up a goats' eye wet-lab model for teaching trabeculectomy for Ophthalmology residents. It details the approaches to eyeball preparation, steps of surgery, application and release of two representative types of 'releasable sutures' in a step-by-step manner. Conclusion: A systematic approach using goats' eye model to teach trabeculectomy and releasable suture techniques can enhance residents' understanding, confidence and expertise to operate upon human eyes.


Assuntos
Glaucoma/cirurgia , Internato e Residência , Modelos Animais , Oftalmologia/educação , Técnicas de Sutura/educação , Trabeculectomia/educação , Animais , Competência Clínica , Avaliação Educacional , Cabras , Pressão Intraocular , Curva de Aprendizado , Retalhos Cirúrgicos/cirurgia
7.
Sci Rep ; 10(1): 21219, 2020 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-33277572

RESUMO

Monitoring volcanic activity along the submarine volcanoes that are usually induced by subsurface magmatism is a challenge. We present fresh set of Ocean Bottom Seismometer (OBS) data that shows geophysical evidence indicative of subsurface magmatism along the submarine volcanoes in the off Nicobar region, Andaman Sea. In this region, we observed for the first time, hybrid very long-period earthquakes documented by passive OBS experiment. These events were initiated by high-frequency (5-10 Hz) with a clear onset of P-phase followed by low-frequency (0.01-0.5 Hz) oscillations in the range of 300-600 s with a prominent high-frequency (10-40 Hz) hydro-acoustic phase. A total of 141 high-frequency events were detected on 21st and 22nd March 2014 out of which 71 were of low-frequency oscillations. These events are distributed in the northwest-southeast direction along the submarine volcanic arc and Seulimeum strand of Great Sumatra fault. Off Nicobar region has been witnessing frequent earthquake swarms since 26th December 2004 tsunamigenic Sumatra earthquake. These swarms occurred in January 2005, March and October 2014, November 2015 and March 2019. The occurrence of low-frequency earthquakes and prominent hydro-acoustic phase are suggestive of sub-surface tectonic and magmatic influence. We propose that upward movement of magma pulses from deeper magma reservoir to the shallow magma chamber activated the strike-slip movement of sliver faults and induced earthquake swarms in the off Nicobar region.

8.
Lung India ; 37(5): 394-399, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32883898

RESUMO

CONTEXT: Fractional exhaled nitric oxide (FeNO) is a noninvasive test for airway inflammation in asthma. The usefulness of FeNO in predicting exacerbations is uncertain. AIMS: The study aims to assess and compare the ability of FeNO, spirometry, and asthma control test (ACT) in predicting future exacerbations of asthma and their correlation with each other. SETTINGS AND DESIGN: This prospective, cohort study was conducted at the Department of Respiratory Medicine, Kasturba Medical College, Manipal. MATERIALS AND METHODS: Adult asthma patients of age 18-65 years were included. Patients with a smoking history of >10 pack-years and those in whom spirometry was contraindicated were excluded. Patients who consented underwent FeNO and spirometry. The control of asthma was assessed using the ACT questionnaire. We captured the number of exacerbations in the follow-up period of 4 months. STATISTICAL ANALYSIS USED: Mann-Whitney test was used to compare the utility of FeNO, spirometry, ACT in predicting exacerbations and Spearman's correlation coefficient was used to ascertain the correlation among them. RESULTS: Of 154 study patients, 28% had exacerbations. We found that there was no significant difference in FeNO in patients with and without exacerbations. The median (interquartile range [IQR]) FEV1% in the patients with and without exacerbations were 68 (55-79) and 75 (65-88), respectively (P = 0.013). The median (IQR) ACT score in patients with exacerbations was 12 (10-16) which was significantly lower than in those without exacerbation in whom it was 16 (14-18) (P = 0.003). There was a negative correlation of ACT with FeNO (Correlation coefficient: -0.167, P = 0.038). The median (IQR) FeNO level (ppb) was lower in patients who were on inhaled corticosteroid (ICS) than in the other group values being 22 (14-38) and 30 (17-58), respectively (P = 0.05). CONCLUSIONS: In our study, FEV1% and ACT score could predict exacerbations of asthma whereas FeNO could not. FeNO level correlated inversely with ACT score. FeNO level decreased with inhaled corticosteroid usage.

9.
BMC Biotechnol ; 20(1): 46, 2020 08 26.
Artigo em Inglês | MEDLINE | ID: mdl-32843009

RESUMO

BACKGROUND: Cellulose, the most versatile biomolecule on earth, is available in large quantities from plants. However, cellulose in plants is accompanied by other polymers like hemicellulose, lignin, and pectin. On the other hand, pure cellulose can be produced by some microorganisms, with the most active producer being Acetobacter xylinum. A. senengalensis is a gram-negative, obligate aerobic, motile coccus, isolated from Mango fruits in Senegal, capable of utilizing a variety of sugars and produce cellulose. Besides, the production is also influenced by other culture conditions. Previously, we isolated and identified A. senengalensis MA1, and characterized the bacterial cellulose (BC) produced. RESULTS: The maximum cellulose production by A. senengalensis MA1 was pre-optimized for different parameters like carbon, nitrogen, precursor, polymer additive, pH, temperature, inoculum concentration, and incubation time. Further, the pre-optimized parameters were pooled, and the best combination was analyzed by using Central Composite Design (CCD) of Response Surface Methodology (RSM). Maximum BC production was achieved with glycerol, yeast extract, and PEG 6000 as the best carbon and nitrogen sources, and polymer additive, respectively, at 4.5 pH and an incubation temperature of 33.5 °C. Around 20% of inoculum concentration gave a high yield after 30 days of inoculation. The interactions between culture conditions optimized by CCD included alterations in the composition of the HS medium with 50 mL L- 1 of glycerol, 7.50 g L- 1 of yeast extract at pH 6.0 by incubating at a temperature of 33.5 °C along with 7.76 g L- 1 of PEG 6000. This gave a BC yield of wet weight as 469.83 g L- 1. CONCLUSION: The optimized conditions of growth medium resulted in enhanced production of bacterial cellulose by A. senegalensis MA1, which is around 20 times higher than that produced using an unoptimized HS medium. Further, the cellulose produced can be used in food and pharmaceuticals, for producing high-quality paper, wound dressing material, and nanocomposite films for food packaging.


Assuntos
Acetobacter/metabolismo , Técnicas de Cultura de Células/métodos , Celulose/biossíntese , Meios de Cultura/química , Acetobacter/crescimento & desenvolvimento , Carbono , Gluconacetobacter xylinus , Glicerol , Concentração de Íons de Hidrogênio , Nitrogênio , Temperatura
10.
J Glaucoma ; 29(5): e28-e30, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32097255

RESUMO

In this report, the authors highlight 2 effective and simple techniques of video documentation of the anterior chamber angle using the newer generation iPhone, iPhone 11 Pro Max. In these techniques, we also used a commercially available macro lens with the phone. The patient positions his/her chin on a slit-lamp biomicroscope as done during a routine slit-lamp examination. The first observer places the gonioscope over the patient's eye and projects a thin slit beam of light of the slit-lamp biomicroscope along the superior or inferior Gonio mirror. A second observer records the anterior chamber angle findings using the macro lens clipped smartphone after bringing it closer to the eye of the patient. In the phone, the video mode is selected after opening the phone's camera application. In the subcategory of video mode, 1× or the wide-angle mode is chosen. Under 1× mode, the magnification is further increased to 3× to document high-quality imaging findings of angle. Similarly, in the second technique, the slit (streak) light beam of the direct ophthalmoscope was used that completely circumvented the need for a slit lamp as a source of light.


Assuntos
Segmento Anterior do Olho/diagnóstico por imagem , Diagnóstico por Imagem/instrumentação , Técnicas de Diagnóstico Oftalmológico/instrumentação , Documentação/métodos , Glaucoma de Ângulo Fechado/diagnóstico por imagem , Glaucoma de Ângulo Aberto/diagnóstico por imagem , Smartphone/instrumentação , Feminino , Gonioscopia , Humanos , Masculino , Lâmpada de Fenda
11.
Nanomaterials (Basel) ; 9(10)2019 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-31590297

RESUMO

: The presence of denatured proteins within a therapeutic drug product can create a series of serious adverse effects, such as mild irritation, immunogenicity, anaphylaxis, or instant death to a patient. The detection of protein degradation is complicated and expensive due to current methods associated with expensive instrumentation, reagents, and processing time. We have demonstrated here a platform for visual biosensing of denatured proteins that is fast, low cost, sensitive, and user friendly by exploiting the plasmonic properties of noble metal nanoparticles. In this study we have exposed artificially heat stressed ferritin and gold nanoparticles to 3-aminopropyl triethoxysilane, which degrades the protein by showing a systematic blue shift in the absorbance spectra of the gold nanoparticle/ferritin and aminosilane solution. This blue shift in absorbance produces a detectable visual color transition from a blue color to a purple hue. By studying the Raman spectroscopy of the gold nanoparticle/ferritin and aminosilane solution, the extent of ferritin degradation was quantified. The degradation of ferritin was again confirmed using dynamic light scattering and was attributed to the aggregation of the ferritin due to accelerated heat stress. We have successfully demonstrated a proof of concept for visually detecting ferritin from horse spleen that has experienced various levels of degradation, including due to heat stress.

13.
J Contemp Dent Pract ; 18(10): 911-914, 2017 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-28989129

RESUMO

INTRODUCTION: Alginate is a versatile, irreversible hydrocolloid impression material, which is cost-effective and forms an essential component in dental practice. For elevating the hardness of the cast models, hardeners are combined with stone. Hence, we planned the present study to evaluate the impact of altering the time of contact between alginate and stone after various interim periods. MATERIALS AND METHODS: The present study included the assessment of impact of time of contact between alginate and stone by the construction of 90 casts using a cylinder model. Two bisecting lines were marked and were named as y and y'. These lines were used for testing the dimensional stability. Using chemically cured acrylic resin, the construction of ten special trays was done. All the impression casts were randomly divided into two study groups, with 45 casts in each group-group I: control group, casts were removed after 60 minutes; group II: study group, casts were removed after 9 hours. A digital caliper was used for measuring the dimensional stability of the cast. All the data were collected and analyzed. RESULTS: In the specimens of the control group (group I) and the study group (group II), the mean dimensions from y to y' were found to be 17.54 and 17.95 respectively. The mean reading of hardness in the control group and study group was found to be 0.59 and 0.20 respectively. In groups I and II, the number of specimens showing clarity of two lines (X and X") was 0 and 5 respectively. CONCLUSION: There was no change in the dimensional stability of the dental stone model when the contact time was increased. CLINICAL SIGNIFICANCE: Within certain limits, the contact time between alginate and stone can be altered without significantly altering the properties of the cast.


Assuntos
Alginatos/metabolismo , Sulfato de Cálcio/metabolismo , Modelos Dentários , Técnica de Fundição Odontológica , Materiais para Moldagem Odontológica/metabolismo , Ácido Glucurônico/metabolismo , Ácidos Hexurônicos/metabolismo , Humanos , Técnicas In Vitro , Fatores de Tempo
14.
J Contemp Dent Pract ; 18(10): 923-926, 2017 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-28989131

RESUMO

BACKGROUND: Luting agents used to fix artificial prostheses, such as fixed partial denture (FPD) to tooth are basically viscous in nature and show chemical reaction for fixation. Postcementation hypersensitivity is a frequent complaint of patients. The present study was conducted to compare postcementation hypersensitivity with zinc phosphate and self-adhesive resin in complete coverage crown. MATERIALS AND METHODS: This study included 30 patients in which 60 porcelein fused to metal crowns was placed. Two metal crowns were placed in each patient in nonantagonis-tic contralateral quadrants. First crown was cemented with zinc phosphate cement, while the other was cemented with self-adhesive resin. Hypersensitivity was evaluated by visual analog scale (VAS) score and by clinical test. For clinical evaluation of sensitivity, hot and cold water was applied to the cervical margin of restoration for 5 seconds and response was recorded. RESULTS: This study consisted of 30 patients in which 60 crowns were given. There was no statistical difference in VAS score of mastication in zinc phosphate cement recorded at baseline, 1 week, 4 weeks, 6 months, 1 year, and 2 years (p > 0.05). Cold response also did not show a significant difference at six time points. Warm response showed slight decrease in subsequent time points but was nonsignificant (p > 0.05). Similarly, with self-adhesive resin cement, VAS score during mastication, hot and cold response was statistically nonsignificant (p > 0.05). CONCLUSION: Postcementation hypersensitivity is a frequent complaint that patient may experience. However, we found no statistically significant difference in both cements tested. CLINICAL SIGNIFICANCE: Postcementation hypersensitivity is an unpleasant sensation experienced by patients. This may affect the success of any prosthesis. Thus, selection of luting agent for cementation plays an important role to eliminate this symptom.


Assuntos
Cerâmica/uso terapêutico , Coroas , Dermatite de Contato/etiologia , Fosfatos/uso terapêutico , Cimentos de Resina/uso terapêutico , Compostos de Zinco/uso terapêutico , Cerâmica/efeitos adversos , Coroas/efeitos adversos , Cimentos Dentários/efeitos adversos , Cimentos Dentários/uso terapêutico , Humanos , Fosfatos/efeitos adversos , Estudos Prospectivos , Cimentos de Resina/efeitos adversos , Compostos de Zinco/efeitos adversos
15.
Dalton Trans ; 46(37): 12507-12515, 2017 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-28901363

RESUMO

Density functional theory (DFT, B3LYP-D3 with implicit solvation in toluene) was used to investigate the mechanisms of olefin hydrosilylation catalyzed by PDI(Fe) (bis(imino)pyridine iron) complexes, where PDI = 2,6-(ArN[double bond, length as m-dash]CMe)2(C5H3N) with Ar = 2,6-R2-C6H3. We find that the rate-determining step for hydrosilylation is hydride migration from Et3SiH onto the Fe-bound olefin to form (PDI)Fe(alkyl)(SiEt3). This differs from the mechanism for the Pt Karstedt catalyst in that there is no prior Si-H oxidative addition onto the Fe center. (PDI)Fe(alkyl)(SiEt3) then undergoes C-Si reductive elimination to form (PDI)Fe, which coordinates an olefin ligand to regenerate the resting state (PDI)Fe(olefin). In agreement with experimental observations, we found that anti-Markovnikov hydride migration has a 5.1 kcal mol-1 lower activation enthalpy than Markovnikov migration. This system has an unusual anti-ferromagnetic coupling between high spin electrons on the Fe center and the unpaired spin in the pi system of the non-innocent redox-active PDI ligand. To describe this with DFT, we used the "broken-symmetry" approach to establish the ground electronic and spin state of intermediates and transition states over the proposed catalytic cycles.

16.
Sci Rep ; 7(1): 2604, 2017 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-28572597

RESUMO

Every year pharmaceutical companies use significant resources to mitigate aggregation of pharmaceutical drug products. Specifically, peptides and proteins that have been denatured or degraded can lead to adverse patient reactions such as undesired immune responses. Current methods to detect aggregation of biological molecules are limited to costly and time consuming processes such as high pressure liquid chromatography, ultrahigh pressure liquid chromatography and SDS-PAGE gels. Aggregation of pharmaceutical drug products can occur during manufacturing, processing, packaging, shipment and storage. Therefore, a facile in solution detection method was evaluated to visually detect denatured glutathione peptides, utilizing gold nanoparticle aggregation via 3-Aminopropyltreithoxysilane. Glutathione was denatured using a 70 °C water bath to create an accelerated heat stressed environment. The peptide, gold nanoparticle and aminosilane solution was then characterized via, UV-Vis spectroscopy, FTIR spectroscopy, dynamic light scattering and scanning electron microscopy. Captured images and resulting absorbance spectra of the gold nanoparticle, glutathione, and aminosilane complex demonstrated visual color changes detectable with the human eye as a function of the denaturation time. This work serves as an extended proof of concept for fast in solution detection methods for glutathione peptides that have experienced heat stress.


Assuntos
Glutationa/metabolismo , Resposta ao Choque Térmico , Peptídeos/metabolismo , Produtos Biológicos/química , Produtos Biológicos/metabolismo , Estabilidade de Medicamentos , Glutationa/química , Ouro/química , Proteínas de Choque Térmico/química , Proteínas de Choque Térmico/metabolismo , Temperatura Alta , Humanos , Nanopartículas Metálicas/química , Imagens de Fantasmas , Propilaminas/química , Agregados Proteicos , Desnaturação Proteica , Silanos/química , Percepção Visual
17.
Langmuir ; 33(1): 11-18, 2017 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-27992713

RESUMO

The ability to control the growth of materials with nanosized precision as well as a complex hollow morphology provides rationale for the study of systems comprising both characteristics. This study explores the design of TiO2 hollow nanotube shells deposited by atomic layer deposition (ALD) on vertically aligned SnO2 nanorods grown using the vapor-liquid-solid technique. The sacrificial template approach in combination with highly conformal coating advantages of ALD resulted in a highly reproducible method to create a large surface area covered by TiO2-protected SnO2 nanorods, which are about 60-100 nm in diameter and approximately 1 µm in length. ZnO was used as a sacrificial layer to create a 30 nm gap between SnO2 nanorods and 10 nm of TiO2 shells. Chemical etching of the sacrificial layer was used to create the desired hollow nanocomposite. A coin half-cell battery has been assembled using the TiO2-protected SnO2 nanorods as an anode electrode and lithium foil as a counter electrode and tested for lithium storage during 70 cycles of charge/discharge in a range of 0.5-2.5 V. The TiO2 hollow shell functioned as a good and robust enhancer for both absolute capacity and current rate capabilities of vertically aligned SnO2 nanorods; an improvement in cyclic stability was also observed. This advanced self-standing hollow configuration provides several unique advantages for energy storage device applications including enhanced lithiation for superior energy storage performance.

18.
Sci Rep ; 6: 26763, 2016 05 31.
Artigo em Inglês | MEDLINE | ID: mdl-27240537

RESUMO

Graphene Oxide (GO) based low cost flexible electronics and memory cell have recently attracted more attention for the fabrication of emerging electronic devices. As a suitable candidate for resistive random access memory technology, reduced graphene oxide (RGO) can be widely used for non-volatile switching memory applications because of its large surface area, excellent scalability, retention, and endurance properties. We demonstrated that the fabricated metal/RGO/metal memory device exhibited excellent switching characteristics, with on/off ratio of two orders of magnitude and operated threshold switching voltage of less than 1 V. The studies on different cell diameter, thickness, scan voltages and period of time corroborate the reliability of the device as resistive random access memory. The microscopic origin of switching operation is governed by the establishment of conducting filaments due to the interface amorphous layer rupturing and the movement of oxygen in the GO layer. This interesting experimental finding indicates that device made up of thermally reduced GO shows more reliability for its use in next generation electronics devices.

19.
Mater Sci Eng C Mater Biol Appl ; 65: 116-25, 2016 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-27157734

RESUMO

Theophylline is an inexpensive drug employed in asthma and chronic obstructive pulmonary disorder medications and is toxic at higher concentration. The development of a molecularly imprinted polymer based theophylline electrochemical sensor on glassy carbon electrode by the electropolymerization of 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid is being discussed in this work. The MIP modification enhances the theophylline recognition ability and the electron transfer kinetics of the bare electrode. The parameters, controlling the performance of the imprinted polymer based sensor, like number of electropolymerization cycles, composition of the pre-polymerization mixture, pH and immersion time were investigated and optimized. The interaction energy and the most stable conformation of the template-monomer complex in the pre-polymerization mixture were determined computationally using ab initio calculations based on density functional theory. The amperometric measurements showed that the developed sensor has a method detection limit of 0.32µM for the dynamic range of 0.4 to 17µM, at optimized conditions. The transducer possesses appreciable selectivity in the presence of structurally similar interferents such as theobromine, caffeine and doxofylline. The developed sensor showed remarkable stability and reproducibility and was also successfully employed in theophylline detection from commercially available tablets.


Assuntos
Técnicas Eletroquímicas , Impressão Molecular , Polímeros/química , Teofilina/análise , Cafeína/química , Carbono/química , Espectroscopia Dielétrica , Eletrodos , Humanos , Concentração de Íons de Hidrogênio , Limite de Detecção , Microscopia de Força Atômica , Teobromina/química , Teofilina/análogos & derivados , Teofilina/sangue , Teofilina/química , Teofilina/urina , Compostos de Estanho/química
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