A voltage-controlled ring oscillator (VCO) based on a full enhancement-mode InAlAs/InGaAs/InP high electron mobility transistor (HEMT) logic is proposed. An enhancement-mode HEMT (E-HEMT) is fabricated, whose threshold is demonstrated to be 10 mV. The model of the E-HEMT is established and used in the SPICE simulation of the VCO. The result proves that the full E-HEMT logic technology can be applied to the VCO. And compared with the HEMT DCFL technology, the complexity of our fabrication process is reduced and the reliability is improved.
A series of copper phthalocyanine (CuPc)-based organic small molecules were prepared through vapor-phase reaction. Nanoscale phase separation was observed with tunable CuPc and copper phthalocyaninato iodide (CuPcI) phase content by changing the iodine ratio. The Seebeck coefficient of the samples was significantly enhanced, which is considered to be attributed to the enhanced surface polarization effect due to the formation of a great number of nanoscale interfaces between the CuPc phase and the CuPcI phase. In addition, these nanointerfaces also gave rise to increased phonon scattering and therefore significantly reduced the lattice thermal conductivity of the small-molecule samples. As a result of the combination of the synergistically optimized electrical and thermal transport properties, the maximum ZT value reaches 3.0 × 10–2 at room temperature, which is among the highest values for small-molecule charge-transfer complex reported so far. Our results shed light on optimizing the thermoelectric performance of organic small molecules by introducing nanoscale phase separations and tailoring the nanoscale interfaces.
Many scholars have made contributions on the formulae of the colloidal dispersion gel (CDG) and the factors affecting on the gelation performance.However,few reports were concentrated on studying the microstructure of the CDG.Polyacrylamide(HPAM)/ Chromium acetate and HPAM/phenolic aldehyde colloidal dispersion gel ,which come respectively from different cross linking systems,inorganic and organic,were studied by the microscopic image analysis with the atomic force microscope(AFM).All of the CDG is founded to present eventually a self assembly branch like fractal structure under the scanning range of micrometer magnitude,and the fractal of a single twig was formed by compact stock of nanometer particles on a smaller scale regardless of the concentration variation of HPAM and the cross linking reagent in either inorganic cross linking system or organic cross linking system.It is revealed that formation and morphology of the branch like fractal structure depend on the concentration of HPAM,and the presence and concentration of cross linking reagent only affect the topography of branch like gel fractal.Moreover,the experimental results demonstrate that the elastic modulus of the gel with the fractal structure formed by the nanometer colloid particles is higher one order of magnitude than that by micrometer ones,and that the smaller the particle diameter is,the higher the gel kinetic stability is.
Root growth has a fundamental role in nitrogen (N) use efficiency. Nevertheless, little is known about how modern breeding progress has affected root growth and its responses to N supply. The root and shoot growth of a core set of 11 representative Chinese maize (Zea mays L.) hybrids released between 1973 and 2009 were investigated under high N (4 mmol L−1, HN) and low N (0.04 mmol L−1, LN) levels in a solution culture system. Compared with LN, HN treatment decreased root dry weight (RDW), the root: shoot ratio (R/S), and the relative growth rate for root dry weight (RGRroot), but increased the total root length (TRL) and the total lateral root length (LRL). The total axial root length (ARL) per plant was reduced under HN, mostly in hybrids released before the 1990s. The number of seminal roots (SRN) was largely unaffected by different N levels. More recently released hybrids showed higher relative growth rates in the shoot under both HN and LN. However, the roots only showed increased RGR under HN treatment. Correspondingly, there was a positive linear relationship with the year of hybrid release for TRL, LRL and ARL under HN treatment. Together, these results suggest that while shoot growth of maize has improved, its root growth has only improved under high N conditions over the last 36 years of selective breeding in China. Improving root growth under LN conditions may be necessary to increase the N use efficiency of maize.
In this work, the authors report an effective one‐pot method to prepare poly(ε‐caprolactone) (PCL)‐incorporated bovine serum albumin (BSA)/calcium alginate/hydroxyapatite (HAp) nanocomposite (NC) scaffolds by templating oil‐in‐water high internal phase emulsion (HIPE), which includes alginate, BSA, and HAp in water phase and PCL in oil phase. The water phase of HIPEs is solidified to form hydrogels containing emulsion droplets via gelation of alginate induced by Ca 2+ ions released from HAp. And the prepared hydrogels are freeze‐dried to obtain PCL‐incorporated porous scaffolds. The obtained scaffolds possess interconnected pore structures. Increasing PCL concentration clearly enhances the compressive property and BSA stability, decreases the swelling ratio of scaffolds, which assists in improving the scaffold stability. The anti‐inflammatory drug ibuprofen can be highly efficiently loaded into scaffolds and released in a sustained rate. Furthermore, mouse bone mesenchymal stem cells can successfully proliferate on the scaffolds, proving the biocompatibility of scaffolds. All results show that the PCL‐incorporated NC scaffolds possess promising potentials in tissue engineering application. image
Straw returning is an effective way to improve soil quality. Whether the bacterial community development has been changed by long-term straw returning in non-calcareous soil is not clear. In this study, the following five treatments were administered: soil without fertilizer (CK); wheat and corn straw returning (WC); wheat straw returning with 276 kg N ha−1 yr−1 (WN); manure, 60,000 kg ha−1 pig manure compost (M) and wheat and corn straw returning with 276 kg N ha−1 yr−1 (WCN). The high-throughput 16S rRNA sequencing technology was used to evaluate the bacterial communities. The results showed that the community was composed mostly of two dominant groups (Proteobacteria and Acidobacteria). Bacterial diversity increased after the application of straw and manure. Principal component analyses revealed that the soil bacterial community differed significantly between treatments. The WCN treatment showed relatively higher total soil N, available P, available K, and organic carbon and invertase, urease, cellulase activities and yield than the WC treatment. Our results suggested that application of N fertilizer to straw returning soil had significantly higher soil fertility and enzyme activity than straw returning alone, which resulted in a different bacterial community composition, Stenotrophomonas, Pseudoxanthomonas, and Acinetobacter which were the dominant genera in the WC treatment while Candidatus, Koribacter and Granulicella were the dominant genera in the WCN treatment. To summarize, wheat and maize straw returning with N fertilizer would be the optimum proposal for improving soil quality and yield in the future in non-calcareous fluro-acquic-wheat and maize cultivated soils in the North China Plain in China.
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