This paper reviews and reports our work on the development of polymeric light-emitting diodes (LEDs) based on Langmuir-Blodgett (LB) films. We have used LB deposition technique as a tool to fabricate dc and ac LEDs with a precise thickness ranging from a few molecular layers to tens of layers. In de LEDs, we have shown that as few as three LB layers of active polymer can yield the same luminance as the thicker ones. With the advantage of LB deposition technique to fabricate heterostructure (multilayer) devices, we have used carrier transporting materials and carrier blocking LB films to control and balance the charge injections in dc LEDs. The frequency dependence of (multilayered) ac LEDs has been studied and moderately high-frequency (20 kHz) electroluminescence (EL) intensity has been obtained. From the transient EL measurements, the role of interfaces in polymeric LEDs has been emphasized and the operation mechanism of LED's has been discussed 相似文献
Excess molar volumes,VEm, and viscosities,, were measured as a function of composition for the binary mixtures of diethylene glycol dibutyl ether+dimethyl carbonate, +diethyl carbonate, and +propylene carbonate at temperatures of 298.15, 308.15, and 318.15 K and atmospheric pressure over the whole range of mixture compositions. From the experimental results, deviations in the viscosity,ln, and excess free energies of activation of viscous flow,G*E, were calculated. The experimental results were correlated using the Redlich–Kister equation. The experimental and calculated quantities were used to analyze the mixing behavior of the components. Furthermore, activation enthalpies,H*, and entropies,S*, of viscous flow were evaluated and their variation with concentration is discussed. 相似文献
Estimates of the abundance and production of Daphnia carinata in six mass culture experiments revealed higher values in the cow dung medium compared with other manures tested. Average production ranged from 1.2 to 223 mg m−3 wk−1 and average biomass of the population from 1.3 to 194 mg m−3 wk−1. The P/B coefficient was highest in the mohua (Madhuca indica) oil cake (1.15) and lowest in the poultry manure (0.77). Daphnia started reproducing at the age of 6–9 days in different culture media. Longevity was higher in the field ( 36 days) than in the laboratory. The total numbers of offspring per female was closely correlated with the mean number of eggs per female in her life span. The intrinsic rate (r) and the finite rate (e') of population of growth of Daphnia were markedly higher in the field than in the laboratory. 相似文献
Banana is one of the most important tropical fruits, and India ranks first in its world production. Banana cultivars rich in provitamin A carotenoids may offer a potential food source for alleviating vitamin A deficiency, particularly in developing countries. With a view to exploit banana peels as a source of valuable components, in the present study, proximate composition, carotenoids, beta‐carotene and some anti‐oxidative enzymes as well as carbohydrate content of selected Indian banana varieties were determined. Karpooravalli cultivar of banana showed the maximum accumulation of carotenoid content in the non‐edible (68 μg g?1 d.w.) portion of banana, while being the second highest in beta‐carotene content (143.12 μg per 100g). However, Red Banana ranked highest in total carotenoid contents for pulp (4 μg g?1 d.w.) and beta‐carotene was estimated to be the highest in the case of peels (241.91 μg per 100g) and in pulp (117.2 μg per 100g). Karpooravalli cultivar of banana is also rich in carbohydrate content in terms of total starch (1786.0 μg g?1 d.w. in peels and 544.85 μg g?1 d.w. in pulp) and sugars (53.53 μg g?1 d.w. in peels and 39.05 μg g?1 d.w. in pulp). The catalase enzyme activity in these peels ranged from 5.66 to 35.57 nmol min?1 mg?1 proteins and was found at a higher level in cultivar Poovan, while the ascorbate peroxidase showed the range of 2.25 to 6.22 μmol min?1 mg?1 proteins. The peels of cultivars Red Banana and Karpooravalli are rich source of bioactive compounds, such as carotenoids (beta‐carotene), anti‐oxidative enzymes and carbohydrate contents. 相似文献
This paper will describe the solid oxide membrane (SOM) process as it applies to the energy-efficient and environmentally sound production of magnesium from magnesium oxide. Also, it will describe the challenges encountered while using this process for the production of transition metals like titanium from its higher oxides. Finally, a novel magnesiothermic SOM process will be proposed that can enable production of transition metals from its higher oxides. 相似文献
Characteristic mineral assemblage and special features of the composition of Au and Ag sulfides of gold-silver deposits have been established. The forms of the occurrence of Au and Ag in the minerals of the early and last stages have been analyzed. The conditions for the formation of uytenbogaardtite and petrovskaite in supergene and low-temperature hydrothermal processes have been considered. A thermodynamic model explaining their genesis in the oxidation zones is presented. 相似文献
The present article describes the effect of steric and electronic factors on the efficiency of initiators based on novel xanthenyl phosphonium salts for cationic polymerization of epoxide monomers. 2-substituted (IH, ICl, IMe, and IOMe) xanthenyl phosphonium hexafluoroantimonate were synthesized and characterized by NMR (1H, 13C and 31P) and IR spectroscopy. The order of initiator activity in polymerization of glycidyl phenyl ether (GPE), was found as IH> ICl>IMe>IOMe. To understand the effect of steric factor, the polymerization of cyclohexene oxide (CHO) was performed and the order of activity was found as ICl>IH>IMe >IOMe. All the initiators were found to be latent at ambient temperature and initiates polymerization on thermal initiation. The order of initiator activity was influenced by electronic and steric factors in the system. The thermal stability of these salts was measured by Thermo gravimetric analysis (TGA). The solubility of the initiators in various organic solvents and epoxy monomers is also discussed. 相似文献
Many modern organizations integrate enterprise resource planning (ERP) and supply chain management (SCM) systems, as they work in a complementary fashion. This often results in technical and organizational challenges. Neway, a Chinese organization, recently went through this complex process. This required efficient procurement and management of hardware, software, and human resources for successful completion. The integrated system was found to improve operations, foster a paperless environment, and provide efficient inventory tracking and picking. It also had several tangible benefits, including reduced lead time and improved inventory accuracy. ERP and SCM systems integration is still a novel concept for a Chinese manufacturing organization. Our case study details the organization's experience, identifies challenges that were faced, and describes solutions adopted to overcome them. 相似文献
An integrated regional model is proposed for rain-rate retrievals over land/ocean from the brightness temperature (Tb) values of the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI). The polarization-corrected temperature calculated from the 85.5-GHz channels is also considered as one of the inputs along with the nine channel Tb values. This model is applicable over the region between and . For this purpose, an artificial neural network is utilized. The collocated precipitation radar (PR) near-surface rain rates as given by a 2A25 data product is considered as a target value. The methodology consists of the separation of land and ocean pixels, the separation of stratiform and convective pixels over land/ocean, and the selection of important features (inputs) for the multilayer perceptron network by the feature selection technique for each group. For the separation of land/ocean pixels, the Tb values of the 10.65-GHz vertical channel are utilized. The values are utilized to separate the stratiform and convective pixels both over land and ocean. The rain retrieval from the developed model is validated with TRMM PR. Overall result shows the better agreement of the model-retrieved rain rate with the PR observation compared to the TMI (2A12) rain rate particularly over land. The rain retrieved from the developed model is further validated with Doppler weather radar. A reasonably good agreement is observed between these two estimations. 相似文献
Floods are common and recurring natural hazards which damages is the destruction for society. Several regions of the world with different climatic conditions face the challenge of floods in different magnitudes. Here we estimate flood susceptibility based on Analytical neural network (ANN), Deep learning neural network (DLNN) and Deep boost (DB) algorithm approach. We also attempt to estimate the future rainfall scenario, using the General circulation model (GCM) with its ensemble. The Representative concentration pathway (RCP) scenario is employed for estimating the future rainfall in more an authentic way. The validation of all models was done with considering different indices and the results show that the DB model is most optimal as compared to the other models. According to the DB model, the spatial coverage of very low, low, moderate, high and very high flood prone region is 68.20%, 9.48%, 5.64%, 7.34% and 9.33% respectively. The approach and results in this research would be beneficial to take the decision in managing this natural hazard in a more efficient way.