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1.
ACS Sens ; 9(1): 182-194, 2024 01 26.
Artigo em Inglês | MEDLINE | ID: mdl-38207118

RESUMO

A high-performance semiconductor metal oxide gas sensing strategy is proposed for efficient sensor-based disease prediction by integrating a machine learning methodology with complementary sensor arrays composed of SnO2- and WO3-based sensors. The six sensors, including SnO2- and WO3-based sensors and neural network algorithms, were used to measure gas mixtures. The six constituent sensors were subjected to acetone and hydrogen environments to monitor the effect of diet and/or irritable bowel syndrome (IBS) under the interference of ethanol. The SnO2- and WO3-based sensors suffer from poor discrimination ability if sensors (a single sensor or multiple sensors) within the same group (SnO2- or WO3-based) are separately applied, even when deep learning is applied to enhance the sensing operation. However, hybrid integration is proven to be effective in discerning acetone from hydrogen even in a two-sensor configuration through the synergistic contribution of supervised learning, i.e., neural network approaches involving deep neural networks (DNNs) and convolutional neural networks (CNNs). DNN-based numeric data and CNN-based image data can be exploited for discriminating acetone and hydrogen, with the aim of predicting the status of an exercise-driven diet and IBS. The ramifications of the proposed hybrid sensor combinations and machine learning for the high-performance breath sensor domain are discussed.


Assuntos
Acetona , Síndrome do Intestino Irritável , Humanos , Algoritmos , Hidrogênio , Aprendizado de Máquina
2.
ACS Nano ; 17(5): 4404-4413, 2023 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-36825770

RESUMO

Noble metal nanoparticle decoration is a representative strategy to enhance selectivity for fabricating chemical sensor arrays based on the 2-dimensional (2D) semiconductor material, represented by molybdenum disulfide (MoS2). However, the mechanism of selectivity tuning by noble metal decoration on 2D materials has not been fully elucidated. Here, we successfully decorated noble metal nanoparticles on MoS2 flakes by the solution process without using reducing agents. The MoS2 flakes showed drastic selectivity changes after surface decoration and distinguished ammonia, hydrogen, and ethanol gases clearly, which were not observed in general 3D metal oxide nanostructures. The role of noble metal nanoparticle decoration on the selectivity change is investigated by first-principles density functional theory (DFT) calculations. While the H2 sensitivity shows a similar tendency with the calculated binding energy, that of NH3 is strongly related to the binding site deactivation due to preferred noble metal particle decoration at the MoS2 edge. This finding is a specific phenomenon which originates from the distinguished structure of the 2D material, with highly active edge sites. We believe that our study will provide the fundamental comprehension for the strategy to devise the highly efficient sensor array based on 2D materials.

3.
J Korean Neurosurg Soc ; 66(4): 393-399, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-36537033

RESUMO

OBJECTIVE: Chiari II malformation (CM II) is still the main cause of severe morbidity and mortality in children with open neural tube defects (ONTDs). The goal of this study was to validate a CM II model in late-stage chick embryos with surgically induced ONTDs. METHODS: To make the chick embryo model of ONTD, their neural tubes were opened for a length of 5-6 somites at the thoracic level in Hamburger and Hamilton stage 18 chick embryos (n=150). They were reincubated in ovo. up to a total age of 17-21 days. A total of 19 embryos survived and were assigned to either the postoperative day (POD) 14-15 group (n=6) or the POD 17-18 group (n=13). Magnetic resonance imaging (MRI) and histopathologic findings of embryo heads with spinal ONTDs were compared with age-matched normal chick embryos. RESULTS: The chick embryos with ONTDs demonstrated definite and constant structural changes, such as downward displacement of the cerebellum to just above the foramen magnum and narrow and small cerebrospinal fluid spaces in the crowded small posterior fossa. These morphologic features were more prominent in the POD 17-18 group than in the POD 14-15 group. CONCLUSION: This is the first description of CM II with spinal ONTD in a late-stage chick embryo model with MRI and histopathological analysis. The morphological changes of the posterior fossa in this study mimic those of CM II associated with spinal ONTD in humans. This model will facilitate investigation of the pathogenesis of CM II.

4.
Adv Mater ; 35(43): e2206842, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35947765

RESUMO

The sensing performances of gas sensors must be improved and diversified to enhance quality of life by ensuring health, safety, and convenience. Metal-organic frameworks (MOFs), which exhibit an extremely high surface area, abundant porosity, and unique surface chemistry, provide a promising framework for facilitating gas-sensor innovations. Enhanced understanding of conduction mechanisms of MOFs has facilitated their use as gas-sensing materials, and various types of MOFs have been developed by examining the compositional and morphological dependences and implementing catalyst incorporation and light activation. Owing to their inherent separation and absorption properties and catalytic activity, MOFs are applied as molecular sieves, absorptive filtering layers, and heterogeneous catalysts. In addition, oxide- or carbon-based sensing materials with complex structures or catalytic composites can be derived by the appropriate post-treatment of MOFs. This review discusses the effective techniques to design optimal MOFs, in terms of computational screening and synthesis methods. Moreover, the mechanisms through which the distinctive functionalities of MOFs as sensing materials, heterostructures, and derivatives can be incorporated in gas-sensor applications are presented.

5.
Autoimmun Rev ; 18(1): 1-8, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30408580

RESUMO

BACKGROUND: Adrenal insufficiency (AI) is associated with high morbidity and mortality. The aim of this systematic review was to enhance diagnostic approaches and summarize therapeutic strategies in the management of AI in patients with systematic lupus erythematosus (SLE) or antiphospholipid syndrome (APS). METHODS: A literature search of PubMed and Medline databases was performed and 91 publications containing 105 cases were included for the final analysis. RESULTS: The following frequency of clinical signs and symptoms was noted: abdominal pain (39.04%) was the leading symptom, followed by fever (33.33%), vomiting (23.81%), and nausea (19.05%). APS was present in 73%, SLE in 17% of the patients, while 2% had a diagnosis of both, SLE and APS. ACTH stimulation test (ACTHst) was performed in 18% of cases and 76.6% of them were unresponsive towards stimulation. Variable treatment approaches were used: hydrocortisone was most commonly used (38.09%), followed by fludrocortisone (26.67%), prednisolone (20.00%) and volume replacement treatment (11.43%), respectively. CONCLUSIONS: This analysis highlights the importance of an early diagnosis and initiation of therapeutic management when AI is suspected. In line, signs and symptoms related to autoimmune diseases in patients with AI should be reviewed crtitically.


Assuntos
Insuficiência Adrenal/etiologia , Síndrome Antifosfolipídica/complicações , Lúpus Eritematoso Sistêmico/complicações , Adolescente , Insuficiência Adrenal/mortalidade , Insuficiência Adrenal/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Síndrome Antifosfolipídica/imunologia , Criança , Feminino , Humanos , Lúpus Eritematoso Sistêmico/imunologia , Masculino , Pessoa de Meia-Idade , Adulto Jovem
6.
Sci Rep ; 6: 31088, 2016 08 09.
Artigo em Inglês | MEDLINE | ID: mdl-27501986

RESUMO

Somatic cell nuclear transfer (SCNT) provides an excellent model for studying epigenomic reprogramming during mammalian development. We mapped the whole genome and whole methylome for potential anomalies of mutations or epimutations in SCNT-generated dogs with XY chromosomal sex but complete gonadal dysgenesis, which is classified as 78, XY disorder of sex development (DSD). Whole genome sequencing revealed no potential genomic variations that could explain the pathogenesis of DSD. However, extensive but stochastic anomalies of genome-wide DNA methylation were discovered in these SCNT DSD dogs. Persistent abnormal hypermethylation of the SRY gene was observed together with its down-regulated mRNA and protein expression. Failure of SRY expression due to hypermethylation was further correlated with silencing of a serial of testis determining genes, including SOX9, SF1, SOX8, AMH and DMRT1 in an early embryonic development stage at E34 in the XY(DSD) gonad, and high activation of the female specific genes, including FOXL2, RSPO1, CYP19A1, WNT4, ERα and ERß, after one postnatal year in the ovotestis. Our results demonstrate that incomplete demethylation on the SRY gene is the driving cause of XY(DSD) in these XY DSD dogs, indicating a central role of epigenetic regulation in sex determination.


Assuntos
Metilação de DNA , Transtornos do Desenvolvimento Sexual/genética , Técnicas de Transferência Nuclear/efeitos adversos , Proteína da Região Y Determinante do Sexo/genética , Animais , Clonagem de Organismos , Modelos Animais de Doenças , Transtornos do Desenvolvimento Sexual/etiologia , Transtornos do Desenvolvimento Sexual/metabolismo , Cães , Epigênese Genética , Feminino , Disgenesia Gonadal/etiologia , Disgenesia Gonadal/genética , Disgenesia Gonadal/metabolismo , Masculino , Gravidez , Processos de Determinação Sexual , Processos Estocásticos , Testículo/embriologia , Testículo/metabolismo , Cromossomo Y/genética
7.
J Korean Med Sci ; 29(11): 1464-72, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25408576

RESUMO

Mcl-1 and Bcl-xL, key anti-apoptotic proteins of the Bcl-2 family, have attracted attention as important molecules in the cell survival and drug resistance. In this study, we investigated whether inhibition of Bcl-xL influences cell growth and apoptosis against simultaneous treatment of resveratrol and clofarabine in the human malignant mesothelioma H-2452 cells. Resveratrol and clofarabine decreased Mcl-1 protein levels but had little effect on Bcl-xL levels. In the presence of two compounds, any detectable change in the Mcl-1 mRNA levels was not observed in RT-PCR analysis, whereas pretreatment with the proteasome inhibitor MG132 led to its accumulation to levels far above basal levels. The knockdown of Bcl-xL inhibited cell proliferation with cell accumulation at G2/M phase and the appearance of sub-G0/G1 peak in DNA flow cytometric assay. The suppression of cell growth was accompanied by an increase in the caspase-3/7 activity with the resultant cleavages of procaspase-3 and its substrate poly (ADP-ribose) polymerase, and increased percentage of apoptotic propensities in annexin V binding assay. Collectively, our data represent that the efficacy of resveratrol and clofarabine for apoptosis induction was substantially enhanced by Bcl-xL-lowering strategy in which the simultaneous targeting of Mcl-1 and Bcl-xL could be a more effective strategy for treating malignant mesothelioma.


Assuntos
Nucleotídeos de Adenina/farmacologia , Antimetabólitos Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Arabinonucleosídeos/farmacologia , Estilbenos/farmacologia , Proteína bcl-X/genética , Proteína bcl-X/metabolismo , Caspase 3/metabolismo , Caspase 7/metabolismo , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Clofarabina , Pontos de Checagem da Fase G2 do Ciclo Celular/efeitos dos fármacos , Técnicas de Silenciamento de Genes , Humanos , Leupeptinas/farmacologia , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Pontos de Checagem da Fase M do Ciclo Celular/efeitos dos fármacos , Mesotelioma/metabolismo , Mesotelioma/patologia , Mesotelioma Maligno , Proteína de Sequência 1 de Leucemia de Células Mieloides/antagonistas & inibidores , Proteína de Sequência 1 de Leucemia de Células Mieloides/genética , Proteína de Sequência 1 de Leucemia de Células Mieloides/metabolismo , Interferência de RNA , RNA Mensageiro/metabolismo , RNA Interferente Pequeno/metabolismo , Resveratrol , Proteína bcl-X/antagonistas & inibidores
8.
Theriogenology ; 81(9): 1207-13.e1, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24613602

RESUMO

Using in vivo-flushed oocytes from a homogenous dog population and subsequent embryo transfer after nuclear transfer, we studied the effects of donor cells collected from 10 different breeds on cloning efficiency and perinatal development of resulted cloned puppies. The breeds were categorized into four groups according to their body weight: small (≤9 kg), medium (>9-20 kg), large (>20-40 kg), and ultra large (>40 kg). A total of 1611 cloned embryos were transferred into 454 surrogate bitches for production of cloned puppies. No statistically significant differences were observed for initial pregnancy rates at Day 30 of embryo transfer for the donor cells originated from different breeds. However, full-term pregnancy rates were 16.5%, 11.0%, 10.0%, and 7.1% for the donor cells originated from ultra-large breed, large, medium, and small breeds, respectively, where pregnancy rate in the ultra-large group was significantly higher compared with the small breeds (P < 0.01). Perinatal mortality until weaning was significantly higher in small breeds (33.3%) compared with medium, large, or ultra-large breeds where no mortality was observed. The mean birth weight of cloned pups significantly increased proportional to breed size. The highest litter size was examined in ultra-large breeds. There was no correlation between the number of embryo transferred and litter size. Taken together, the efficiency of somatic cell cloning and fetal survival after embryo transfer may be affected significantly by selecting the appropriate genotype.


Assuntos
Clonagem de Organismos/veterinária , Cães/genética , Cães/fisiologia , Fibroblastos , Animais , Animais Recém-Nascidos , Peso Corporal , Transferência Embrionária/veterinária , Embrião de Mamíferos/citologia , Embrião de Mamíferos/embriologia , Feminino , Genótipo , Masculino , Gravidez
9.
PLoS One ; 8(5): e63241, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23704897

RESUMO

The present study was conducted to generate transgenic pigs coexpressing human CD55, CD59, and H-transferase (HT) using an IRES-mediated polycistronic vector. The study focused on hyperacute rejection (HAR) when considering clinical xenotransplantation as an alternative source for human organ transplants. In total, 35 transgenic cloned piglets were produced by somatic cell nuclear transfer (SCNT) and were confirmed for genomic integration of the transgenes from umbilical cord samples by PCR analysis. Eighteen swine umbilical vein endothelial cells (SUVEC) were isolated from umbilical cord veins freshly obtained from the piglets. We observed a higher expression of transgenes in the transgenic SUVEC (Tg SUVEC) compared with the human umbilical vein endothelial cells (HUVEC). Among these genes, HT and hCD59 were expressed at a higher level in the tested Tg organs compared with non-Tg control organs, but there was no difference in hCD55 expression between them. The transgenes in various organs of the Tg clones revealed organ-specific and spatial expression patterns. Using from 0 to 50% human serum solutions, we performed human complement-mediated cytolysis assays. The results showed that, overall, the Tg SUVEC tested had greater survival rates than did the non-Tg SUVEC, and the Tg SUVEC with higher HT expression levels tended to have more down-regulated α-Gal epitope expression, resulting in greater protection against cytotoxicity. By contrast, several Tg SUVEC with low CD55 expression exhibited a decreased resistance response to cytolysis. These results indicated that the levels of HT expression were inversely correlated with the levels of α-Gal epitope expression and that the combined expression of hCD55, hCD59, and HT proteins in SUVECs markedly enhances a protective response to human serum-mediated cytolysis. Taken together, these results suggest that combining a polycistronic vector system with SCNT methods provides a fast and efficient alternative for the generation of transgenic large animals with multiple genetic modifications.


Assuntos
Antígenos CD55/genética , Antígenos CD59/genética , Proteínas do Sistema Complemento/genética , Fucosiltransferases/genética , Técnicas de Transferência de Genes , Porco Miniatura/genética , Suínos/genética , Animais , Animais Geneticamente Modificados , Morte Celular , Separação Celular , Embrião de Mamíferos/metabolismo , Células Endoteliais/metabolismo , Feminino , Fibroblastos/metabolismo , Citometria de Fluxo , Galactose/metabolismo , Expressão Gênica , Vetores Genéticos/genética , Humanos , Imuno-Histoquímica , Masculino , Especificidade de Órgãos/genética , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Soro , Transgenes
10.
Nanotechnology ; 23(46): 465402, 2012 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-23092968

RESUMO

We demonstrate the fabrication of hybrid nanocomposite electrodes with a combination of SnO(2) nanoparticles (NPs) and conducting multiwalled carbon nanotube (MWCNT) anodes (SnO(2)@CNT) through the direct anchoring of SnO(2) NPs on the surface of electrophoretically pre-deposited MWCNT (EPD-CNT) networks via a metal-organic chemical vapor deposition process. This SnO(2)@CNT nanocomposite displays large reversible capacities of over 780, 510, and 470 mA h g(-1) at 1 C after 100, 500, and 1000 cycles, respectively. This outstanding long-term cycling stability is a result of the uniform distribution of SnO(2) NPs (~8.5 nm), a nanoscale EPD-CNT network with good electrical conductivity, and the creation of open spaces that buffer a large volume change during the Li-alloying/dealloying reaction of SnO(2).

11.
Chem Commun (Camb) ; 48(56): 7061-3, 2012 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-22684325

RESUMO

Germanium (Ge) nanoparticle-multiwalled carbon nanotube (MWCNT) anodes are fabricated through the anchoring of Ge on the surface of electrophoretically pre-deposited MWCNT networks via a thermal evaporation process. This Ge-MWCNT nanocomposite displays a large reversible capacity of over 800 mA h g(-1) at 1 C even after 200 cycles.

12.
Korean J Urol ; 53(3): 171-7, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22468212

RESUMO

PURPOSE: The purpose of our study was to investigate the safety and efficacy of the suprapubic arch (SPARC) sling operation and the transobturator tape (MONARC) sling operation according to body mass index (BMI). MATERIALS AND METHODS: Between January 1, 2004, and July 12, 2009, a retrospective clinical trial was performed with 284 patients treated by the SPARC sling procedure and 49 patients treated by the MONARC sling procedure. The women were classified into 3 groups by BMI according to the WHO Expert Consultation: normal weight (A, BMI 18.5 to 22.9 kg/m²), overweight (B, BMI 23 to 27.5 kg/m²), and obese (C, BMI>27.6 kg/m²). Patients' characteristics and clinical outcomes of the operation were analyzed according to BMI at 1 year after surgery via questionnaires and interviews with the patients about their voiding symptoms and medical records. RESULTS: There were 103 patients in group A, 186 in group B, and 34 in group C. The objective cure rates for groups A, B, and C after the SPARC procedure were 94.4%, 96.7%, and 96.8%, respectively (p=0.321), and the subjective cure rates were 94.4%, 96.1%, and 96.8%, respectively (p=0.222). The objective cure rates for groups A, B, and C after the MONARC procedure were 100.0%, 90.9%, and 66.7%, respectively (p=0.742), and the subjective cure rates were 92.3%, 93.9%, and 66.7%, respectively (p=0.779). The complication rates were similar among the three study groups. CONCLUSIONS: Mid-urethral sling procedures for urinary incontinence result in similar objective and subjective cure rates and postoperative complications irrespective of BMI.

13.
Nanoscale Res Lett ; 7(1): 10, 2012 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-22222097

RESUMO

One of the most promising anode materials for Li-ion batteries, Li4Ti5O12, has attracted attention because it is a zero-strain Li insertion host having a stable insertion potential. In this study, we suggest two different synthetic processes to prepare Li4Ti5O12 using anatase TiO2 nanoprecursors. TiO2 powders, which have extraordinarily large surface areas of more than 250 m2 g-1, were initially prepared through the urea-forced hydrolysis/precipitation route below 100°C. For the synthesis of Li4Ti5O12, LiOH and Li2CO3 were added to TiO2 solutions prepared in water and ethanol media, respectively. The powders were subsequently dried and calcined at various temperatures. The phase and morphological transitions from TiO2 to Li4Ti5O12 were characterized using X-ray powder diffraction and transmission electron microscopy. The electrochemical performance of nanosized Li4Ti5O12 was evaluated in detail by cyclic voltammetry and galvanostatic cycling. Furthermore, the high-rate performance and long-term cycle stability of Li4Ti5O12 anodes for use in Li-ion batteries were discussed.

14.
ACS Appl Mater Interfaces ; 3(12): 4682-8, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22053902

RESUMO

Brush-shaped ZnO heteronanostructures were synthesized using a newly designed thermal-assisted pulsed laser deposition (T-PLD) system that combines the advantages of pulsed laser deposition (PLD) and a hot furnace system. Branched ZnO nanostructures were successfully grown onto CVD-grown backbone nanowires by T-PLD. Although ZnO growth at 300 °C resulted in core-shell structures, brush-shaped hierarchical nanostructures were formed at 500-600 °C. Materials properties were studied via photoluminescence (PL), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterizations. The enhanced photocurrent of a SnO(2)-ZnO heterostructures device by irradiation with 365 nm wavelength ultraviolet (UV) light was also investigated by the current-voltage characteristics.

15.
ACS Appl Mater Interfaces ; 3(8): 3140-5, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21744869

RESUMO

The effect of Ag decoration on the gas sensing characteristics of SnO(2) nanowire (NW) networks was investigated. The Ag layers with thicknesses of 5-50 nm were uniformly coated on the surface of SnO(2) NWs via e-beam evaporation, which were converted into isolated or continuous configurations of Ag islands by heat treatment at 450 °C for 2 h. The SnO(2) NWs decorated by isolated Ag nano-islands displayed a 3.7-fold enhancement in gas response to 100 ppm C(2)H(5)OH at 450 °C compared to pristine SnO(2) NWs. In contrast, as the Ag decoration layers became continuous, the response to C(2)H(5)OH decreased significantly. The enhancement and deterioration of the C(2)H(5)OH sensing characteristics by the introduction of the Ag decoration layer were strongly governed by the morphological configurations of the Ag catalysts on SnO(2) NWs and their sensitization mechanism.


Assuntos
Técnicas Eletroquímicas/métodos , Etanol/análise , Nanopartículas Metálicas/química , Nanofios/química , Prata/química , Compostos de Estanho/química , Catálise , Gases/química , Nanopartículas Metálicas/ultraestrutura , Nanofios/ultraestrutura , Temperatura
16.
Chem Commun (Camb) ; 47(33): 9315-7, 2011 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-21503339

RESUMO

Microstructural evolution of spinel Zn(2)SnO(4) nanofibers was manipulated via an in situ phase separation process of inorganic precursors and a matrix polymer during electrospinning and calcination. Chemiresistive gas sensors using porous Zn(2)SnO(4) fibers exhibited superior C(2)H(5)OH sensing response.

17.
Sensors (Basel) ; 11(11): 10603-14, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22346661

RESUMO

A combinatorial hydrothermal reaction has been used to prepare pure and additive (Sb, Cu, Nb, Pd, and Ni)-loaded In2O3 hollow spheres for gas sensor applications. The operation of Pd- and Cu-loaded In2O3 sensors at 371 °C leads to selective H2S detection. Selective detection of CO and NH3 was achieved by the Ni-In2O3 sensor at sensing temperatures of 371 and 440 °C, respectively. The gas responses of six different sensors to NH3, H2S, H2, CO and CH4 produced unique gas sensing patterns that can be used for the artificial recognition of these gases.

18.
Nanotechnology ; 21(48): 485201, 2010 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-21051805

RESUMO

The degradation pattern of SnO(2) nanowire field effect transistors (FETs) was investigated by using an individual SnO(2) nanowire that was passivated in sections by either a PMMA (polymethylmethacrylate) or an Al(2)O(3) layer. The PMMA passivated section showed the best mobility performance with a significant positive shift in the threshold voltage. The distinctive two-dimensional R(s)-µ diagram based on a serial resistor connected FET model suggested that this would be a useful tool for evaluating the efficiency for post-treatments that would improve the device performance of a single nanowire transistor.

19.
Nanotechnology ; 19(9): 095508, 2008 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-21817675

RESUMO

We fabricated a nanowire-based gas sensor using a simple method of growing SnO(2) nanowires bridging the gap between two pre-patterned Au catalysts, in which the electrical contacts to the nanowires are self-assembled during the synthesis of the nanowires. The gas sensing capability of this network-structured gas sensor was demonstrated using a diluted NO(2). The sensitivity, as a function of temperature, was highest at 200 °C and was determined to be 18 and 180 when the NO(2) concentration was 0.5 and 5 ppm, respectively. Our sensor showed higher sensitivity compared to different types of sensors including SnO(2) powder-based thin films, SnO(2) coating on carbon nanotubes or single/multiple SnO(2) nanobelts. The enhanced sensitivity was attributed to the additional modulation of the sensor resistance due to the potential barrier at nanowire/nanowire junctions as well as the surface depletion region of each nanowire.

20.
Nano Lett ; 7(10): 3041-5, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17760477

RESUMO

Novel SnO(2)-In(2)O(3) heterostructured nanowires were produced via a thermal evaporation method, and their possible nucleation/growth mechanism is proposed. We found that the electronic conductivity of the individual SnO(2)-In(2)O(3) nanowires was 2 orders of magnitude better than that of the pure SnO(2) nanowires, due to the formation of Sn-doped In(2)O(3) caused by the incorporation of Sn into the In(2)O(3) lattice during the nucleation and growth of the In(2)O(3) shell nanostructures. This provides the SnO(2)-In(2)O(3) nanowires with an outstanding lithium storage capacity, making them suitable for promising Li ion battery electrodes.


Assuntos
Fontes de Energia Elétrica , Índio/química , Lítio/química , Microeletrodos , Nanotecnologia/instrumentação , Nanotubos/química , Compostos de Estanho/química , Cristalização/métodos , Condutividade Elétrica , Eletroquímica/instrumentação , Eletroquímica/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Íons , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Nanotecnologia/métodos , Nanotubos/ultraestrutura , Tamanho da Partícula , Propriedades de Superfície
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