The effect of nitrogen (0, 80, 120, and 160 kg/ha from urea) and sulphur (0, 20, 40, and 60 kg/ha from gypsum) fertilization on N and S uptake and yield performance of onion (var. BARI Piaz-1) was studied in the research field of Bangladesh Agricultural Research Institute (BARI), Joydebpur, Gazipur during rabi seasons of 2002-2003 and 2003-2004. The experiment was laid out in a randomized complete block design under factorial arrangement with three replications. Addition of nitrogen and sulphur fertilizers exerted significant influence on the number of leaves/plant, plant height, diameter of bulb, single bulb weight, and yield of onion. The uptake of N and S by bulb also significantly responded to the application of nitrogen and sulphur. The highest yield of onion and the maximum uptake of N and S were recorded by the combined application of 120 kg N and 40 kg S/ha with a blanket dose of 90 kg P 2 O 5 , 90 kg K 2 O, and 5 kg Zn/ha plus 5 tons of cowdung/ha. The antagonistic effect of nitrogen and sulphur on the uptake of N and S by bulb, yield components, and yield of onion was observed only when they were applied together at higher rates of nitrogen (160 kg/ha) and sulphur (40kg/ha).

The dielectric constant of polymers was increased by combining flexible segments and rigid polar segments in the polymer backbone.

Metal−polymer interface plays a crucial role in controlling the dielectric performance in all flexible electronics. Ideally, the formation of the Schottky barrier due to the large band offset of the electron affinity of the polymer over the work function of the electrode should sufficiently impede the charge injection. Arguably, however, such an injection barrier has hardly been indisputably verified in polymer−metal junctions due to the everexisting surface states, which dramatically compromise the barrier thus leading to undesired high electrical conduction. Here, we demonstrate experimentally a clear negative correlation between the breakdown strength and the density of surface states in polymer dielectrics. The existence of surface states reduces the effective barrier height for charge injection, as further revealed by density functional theory calculations and photoinjection current measurements. Based on these findings, we present a surface engineering method to enhance the breakdown strength with the application of nanocoatings on polymer films to eliminate surface states. The density of surface states is reduced by 2 orders of magnitude when the polymer is coated with a layer of two-dimensional hexagonal boron nitride nanosheets, leading to about 100% enhancement of breakdown strength. This work reveals the critical role played by surface states on electrical breakdown and provides a versatile surface engineering strategy to curtail surface states, broadly applicable for all polymer dielectrics.

Breakdown strength, the maximum electric field that can be applied on a dielectric polymer without destroying its insulating characteristics, sets an upper limit on the maximum energy that can be stored in this material. Despite its significance, the breakdown strength remains poorly understood and impractical to compute. This is a major challenge in the development of high-energy dielectric polymers for which a large number of candidates must be screened for identifying those with high breakdown strength. In this work, we develop a multistep strategy for accessing the breakdown strength through two proxies that can be computationally estimated in a high-throughput manner, i.e., the polymer band gap and electron injection barrier at electrode–polymer interfaces. First, these properties are experimentally proven (established) to be correlated strongly with the breakdown strength of a number of benchmark polymers. Then, we develop a simple model, which relies on the chain structure of polymers, to estimate their band gap and electron injection barrier at the level of density functional theory. After validation, this model was finally used for 990 polymers, identifying 53 candidates that have preferable proxies, and thus, potentially having high breakdown strength. Because of the past synthesizability evidence of these polymers, we hope that they may be considered to be synthesized and tested in the near future. Moreover, some empirical rules that were extracted from our computed data could be useful for polymer selection and design in general. We note that the strategy used here is generic and can be used to design materials with other attractive, but complex, properties as well.

Nitrogen (N) loss from rice production systems in the form of ammonia (NH3) can be a significant N loss pathway causing significant economic and environmental costs.

Recently, there has been a growing interest in developing wide band gap dielectric materials as the next generation insulators for capacitors, photovoltaic devices, and transistors. Organotin polyesters have shown promise as high dielectric constant, low loss, and high band gap materials. Guided by first-principles calculations from density functional theory (DFT), in line with the emerging codesign concept, the polymer poly(dimethyltin 3,3-dimethylglutarate), p(DMTDMG), was identified as a promising candidate for dielectric applications. Blends and copolymers of poly(dimethyltin suberate), p(DMTSub), and p(DMTDMG) were compared using increasing amounts of p(DMTSub) from 10% to 50% to find a balance between electronic properties and film morphology. DFT calculations were used to gain further insight into the structural and electronic differences between p(DMTSub) and p(DMTDMG). Both blend and copolymer systems showed improved results over the homopolymers with the films having dielectric constants of 6.8 and 6.7 at 10 kHz with losses of 1% and 2% for the blend and copolymer systems, respectively. The energy density of the film measured as a D-E hysteresis loop was 6 J/cc for the copolymer, showing an improvement compared to 4 J/cc for the blend. This improvement is hypothesized to come from a more uniform distribution of diacid repeat units in the copolymer compared to the blend, leading toward improved film quality and subsequently higher energy density.

Flexible films having high dielectric constants with low dielectric loss have promising application in the emerging area of high‐energy‐density materials. Here, for the first time, an organometallic, Sn‐polyester‐containing hybrid free‐standing film in polyimide matrix is reported. Polyimide, pBTDA‐HDA, is used with poly(dimethyltin glutarate) and poly(dimethyltin‐3,3‐dimethyglutarate) (pDMTDMG) for having a processable film with tunable dielectric properties. Hybrid film with 60% pDMTDMG and 40% PI (HB2) is found to have improved dielectric features over previously synthesized organic polyimide and organometallic Sn‐polyester homopolymers. These novel organometallic–organic hybrid systems expanded a new area of dielectrics for next‐generation electronics with superior overall electrical performance.

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