A quantitative study of the dynamics of threshold-voltage shifts with time in gallium-indium zinc oxide amorphous thin-film transistors is presented using standard analysis based on the stretched exponential relaxation. For devices using thermal silicon oxide as gate dielectric, the relaxation time is 3 ϫ 10 5 s at room temperature with activation energy of 0.68 eV. These transistors approach the stability of the amorphous silicon transistors. The threshold voltage shift is faster after water vapor exposure suggesting that the origin of this instability is charge trapping at residual-water-related trap sites. © 2009 American Institute of Physics. ͓DOI: 10.1063/1.3187532͔ Amorphous gallium-indium zinc oxide ͑GIZO͒ thin-film transistors ͑TFTs͒ have attracted attention for their possible applications to flat, flexible, and transparent displays, 1-4 especially when processed at low temperatures. However, like the other TFTs' technologies, they also suffer from a stability phenomena known as gate-bias stress. 5,6 This effect manifests itself as a continuous increase in threshold voltage ͑V th ͒ when the gate bias is kept constant over time. This limits the application of these TFTs in demanding applications, such as active matrix organic light emitting displays. The increase in V th lowers the luminance of individual pixels over time, causing display nonuniformity. 7 As an example, using current technologies several driving transistors per pixel are necessary to compensate for the V th shift. Hence, a proper understanding of the stressing mechanism is of paramount importance.Gate-bias stress effects are commonly reported in the literature for a variety of transistors, a-Si TFTs, 8 organic transistors, 9-11 and recently also in amorphous oxide semiconductors TFTs. [12][13][14][15] The effect has been explained as a slow trapping of charge carriers in defects of unknown origin located at the semiconductor/dielectric interface. 13 It is known that the current degradation is faster when the devices are exposed to atmosphere 15,16 and that the stability improves after annealing. 1 Also, it has been reported that the effects can be reduced by the insertion of a passivation layer, either between the dielectric and the semiconductor 17 or on top of the semiconductor in bottom-gate structures. 16 This work provides a quantitative study of the gate-bias stress instability as a function of temperature and environment conditions. The results allow a comparison with competing TFTs technologies. Furthermore, it also provides evidences that water vapor contamination enhances this instability. Therefore, there is no conceptual limitation for the stability of GIZO based TFTs. This is in contrast to hydrogenated amorphous silicon TFTs where the instability is caused by the creation of intrinsic defects, unsaturated valence states into which electrons are trapped.The device fabrication process has been described in detail elsewhere. 18 Briefly, the TFTs were produced with a staggered bottom gate configuration on silicon wafers, which a...

Airway epithelium plays an important role in the asthma physiopathology. Aerobic exercise decreases Th2 response in murine models of allergic asthma, but its effects on the structure and activation of airway epithelium in asthma are unknown. BALB/c mice were divided into control, aerobic exercise, ovalbumin-sensitized and ovalbumin-sensitized plus aerobic exercise groups. Ovalbumin sensitization occurred on days 0, 14, 28, 42, and aerosol challenge from day 21 to day 50. Aerobic exercise started on day 22 and ended on day 50. Total cells and eosinophils were reduced in ovalbumin-sensitized group submitted to aerobic exercise. Aerobic exercise also reduced the oxidative and nitrosative stress and the epithelial expression of Th2 cytokines, chemokines, adhesion molecules, growth factors and NF-kB and P2X7 receptor. Additionally, aerobic exercise increased the epithelial expression of IL-10 in non-sensitized and sensitized animals. These findings contribute to the understanding of the beneficial effects of aerobic exercise for chronic allergic airway inflammation, suggesting an immune-regulatory role of exercise on airway epithelium.

O presente trabalho teve como objetivo determinar o acúmulo de nutrientes em cultivares de alface cultivadas em condições do semi-árido. O experimento foi conduzido em área experimental da Universidade Federal Rural do Semi-Árido em solo classificado como Argissolo Vermelho-Amarelo. O delineamento experimental utilizado foi em blocos casualizados completos em esquema fatorial 3 x 5 com quatro repetições. Os tratamentos resultaram da combinação de três cultivares de alface (Babá de Verão, Tainá e Verônica) e cinco épocas de coletas (7, 12, 17, 22 e 27 dias após transplantio - DAT). A máxima produção de matéria seca foi obtida aos 27 DAT, sendo de 8,9; 6,9 e 6,4 g planta-1, respectivamente para as cultivares Babá de Verão, Tainá e Verônica. O período de maior demanda para N, P, K e Mg foi de 22 a 27 DAT e para Ca de 17 a 22 DAT, em todas as cultivares. A ordem decrescente dos nutrientes acumulados pelas cultivares de alface foi: K, N, P, Mg e Ca.

RESUMOO objetivo do presente trabalho foi determinar o acúmulo e exportação de nutrientes pela cultura da beterraba em condições de altas temperaturas e luminosidade. O delineamento experimental utilizado foi em blocos casualizados completos com quatro repetições, sendo os tratamentos constituídos pelas épocas de coleta de plantas (20, 30, 40, 50 e 60 dias após semeadura). Em cada coleta foram utilizadas quatro plantas por repetição. O máximo acúmulo de massa seca ocorreu aos 60 DAS, sendo de 21,35 g/planta. A maior demanda de nutriente aconteceu no período de 50 a 60 DAS para N e Mg, 30 a 50 DAS para P, 30 a 40 para K e 40 a 50 DAS para Ca. A ordem decrescente dos nutrientes acumulados pela beterraba foi: N, K, Mg, Ca e P. As quantidades totais de N, P, K, Ca e Mg exportadas pelas raízes foram respectivamente de 88,0; 6,1; 93,2; 12,1 e 16,8 kg/ha. Termos para indexação:Beta vulgaris, nutrição de plantas, crescimento. ABSTRACTThe objective of this research was to determine on field condition the accumulation and exportation of nutrients by beet crop in conditions of high temperatures and radiations intensity. The experimental design was fully randomized blocks, with four replications. The treatments consisted of the sampling times (20, 30, 40, 50 and 60 days after sowing (DAS). The maximum accumulation of dry mass occurred at 60 DAS, being of 21.35 g/plant. The period of higher demand for N and Mg occurred from 50 to 60 DAS, 30 the 50 DAT for P, 30 the 40 for K and 40 the 50 for Ca. The decreasing order of nutrient accumulation by the beet crop was: N, K, Mg, Ca and P. The roots exported 88.0 kg/ha of N; 6.1 kg/ha of P; 93.1 kg/ha of K; 12.1 kg/ha of Ca and 16.8 kg/ha of Mg.

Background Airway inflammation in asthma involves innate immune responses. Toll-like receptors (TLRs) and thymic stromal lymphopoietin (TSLP) are thought to be involved in airway inflammation, but their expression in asthmatics’ both large and small airways has not been investigated. Objective To analyze the expression of TLR2, TLR3, TLR4 and TSLP in large and small airways of asthmatics and compare their expression in smoking and nonsmoking asthmatics; to investigate whether TLR expression is associated with eosinophilic or neutrophilic airway inflammation and with Mycoplasma pneumoniae and Chlamydophila pneumoniae infection. Methods Using immunohistochemistry and image analysis, we investigated TLR2, TLR3, TLR4 and TSLP expression in large and small airways of 24 victims of fatal asthma, FA, (13 nonsmokers, 11 smokers) and 9 deceased control subjects (DCtrl). TLRs were also measured in 18 mild asthmatics (MA) and 12 healthy controls (HCtrl). Mycoplasma pneumoniae and Chlamydophila pneumoniae in autopsy lung tissue was analyzed using real-time polymerase chain reaction. Airway eosinophils and neutrophils were measured in all subjects. Results Fatal asthma patients had higher TLR2 in the epithelial and outer layers of large and small airways compared with DCtrls. Smoking asthmatics had lower TLR2 levels in the inner and outer layers of the small airways than nonsmoking asthmatics. TSLP was increased in the epithelial and outer layers of the large airways of FA. FA patients had greater TLR3 expression in the outer layer of large airways and greater TLR4 expression in the outer layer of small airways. Eosinophilic airway inflammation was associated with TLR expression in the epithelium of FA. No bacterial DNA was detected in FA or DCtrls. MA and HCtrls had only a small difference in TLR3 expression. Conclusions and Clinical Relevance Increased expression of TLR 2, 3 and 4 and TSLP in fatal asthma may contribute to the acute inflammation surrounding asthma deaths.