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Planting mechanization is a main tendency of the whole-course mechanization development in rice production in China; and the rice mechanized transplanting ratio was more than 38% across the country in 2014. Mechanical transplanting rice can enhance the working efficiency and increase planting income. However, the current varieties of mechanical transplanted rice are mostly conventional rice, and the hybrid rice varieties are less used, due to some problems that cause hybrid rice cultivar can't be applied to mechanical transplanting. In order to explore the better technology of mechanical transplanting for exerting the high yield of hybrid rice, and to solve the problems such as the weak seedlings, packing difficulty and high drain hole in field of mechanical transplanting hybrid rice, a field experiment was conducted using hybrid rice cultivars which respectively were Yongyou 2640 (japonica hybrid rice) and Y Liangyou 1 (indicia hybrid rice) in the demonstration base of Huaiyin District and Xuyi County in Jiangsu Province. Three different mechanical transplanting methods were adopted, which included mechanical transplanting of pot seedling (PS), mechanical transplanting of old blanket seedling (OS) and mechanical transplanting of conventional blanket seedling (CS). in The climate conditions in 2014 were representative and consistent with those of recent 3 years in precipitation, sunshine and temperature. The seedling rate in each bowl seedling tray was 40 gram and 35 gram with japonica hybrid rice and indicia hybrid rice respectively for the mechanical transplanting of PS, 60 and 50 gram respectively for the mechanical transplanting of OS, and 80 and 60 gram respectively for the CS. The 3 different ages for mechanical transplanting seedling were 30, 35 and 22 d, and seedlings with different mechanical transplanting were transplanted in the plot of 90 m² (15 m × 6 m) seperately. The nitrogen fertilizer amounts of japonica hybrid rice and indicia hybrid rice were 300 and 225 kg/hm², respectively. The other management measures were uniform with high-yield cultivation. In this experiment, we investigated the yield and its components, the number of culms and tillers, the leaf area index, the composition of leaf area, photosynthetic potential (pp), dry matter production and accumulation, crop growth rate (CGR) and net assimilation rate (NAR) and matter transport in culm and sheath in the high-yield cultivation. Results showed that, the population spikelets of PS and OS were significantly (P<0.05) or very significantly (P<0.01) higher than CS, the filled-grain percentage and 1000-grain weight were slightly higher than CS, and the actual yields of PS and OS were significantly higher (P<0.01) than that of CS, which increased by 20.70%-20.81% and 12.26%-12.94% respectively. The high yield of PS was attributed to seedlings transplanted with soil, shorter rejuvenation period, steady dynamic of tillers, appropriate peak tillers, higher percentage of productive tiller (80%), higher PP, CGR and NAR, greater dry matter accumulation in the middle and late growth stage, and coordinating matter output and transport. The reason of high yield of OS was that its seedling age could extend to 35 d and was transplanted to field with strong tillers, and that the peak tillers were fewer, the percentage of productive tiller was higher (70%), the indices of population were significantly better than CS. Based on the above system analysis, the paper was also suitable for production verification and scientific evaluation on the mechanical planting approach of high-yielding hybrid rice. This article provides an important reference to the development of mechanical transplanting hybrid rice. [ABSTRACT FROM AUTHOR]

Micro thermoelectric devices are expected to further improve the cooling density for the temperature control of electronic devices; nevertheless, the high contact resistivity between metals and semiconductors critically limits their applications, especially in chip cooling with extremely high heat flux. Herein, based on the calculated results, a low specific contact resistivity of ∼10 -7 Ω cm 2 at the interface is required to guarantee a desirable cooling power density of micro devices. Thus, we developed a generally applicable interfacial modulation strategy via localized surface doping of thermoelectric films, and the feasibility of such a doping approach for both n/p-type (Bi,Sb) 2 Te 3 films was demonstrated, which can effectively increase the surface-majority carrier concentration explained by the charge transfer mechanism. With a proper doping level, ultralow specific contact resistivities at the interfaces are obtained for n-type (6.71 × 10 -8 Ω cm 2 ) and p-type (3.70 × 10 -7 Ω cm 2 ) (Bi,Sb) 2 Te 3 layers, respectively, which is mainly attributed to the carrier tunneling enhancement with a narrowed interfacial contact barrier width. This work provides an effective scheme to further reduce the internal resistance of micro thermoelectric coolers, which can also be extended as a kind of universal interfacial modification technique for micro semiconductor devices.

The electrical contact resistance between a metal and semiconductor is one of the keys to improving the output performance of thin-film thermoelectric devices. Herein, we reduced the interface contact resistance by controlling the surface energy of a Sb 2 Te 3 semiconductor via tuning of the crystallization and orientation, preparing an intrinsically compact and flat Sb 2 Te 3 film with high surface energy and low roughness, which can give rise to a low average specific contact resistivity (8.2 × 10 -6 Ω cm 2 ) with a Ni/Cu metal. The improvement in interface electrical properties is due to the increase in the surface energy and decrease in the surface roughness of the semiconductor surface, which lead to a transformation from three-dimensional island-shaped nucleation to two-dimensional layered nucleation for surface-attached metal films, forming a longitudinally tight connection contact with a low resistance. This approach allows the resistivity to become close to the fundamental theoretically calculated limit. Our work provides a new idea for reducing the contact resistivity of thin-film thermoelectric devices, which is conducive to supporting the development of thermoelectric semiconductor planarization.

The application of screen-printed thin-film thermoelectric (TE) devices is still in its infancy, mainly due to low TE performance of screen-printed films and especially the poor electrical transport properties. Herein, we design and prepare a high-performance screen-printed Bi 2 Te 3 film through introducing excessive Te-based nanosolder (Te-NS) to simultaneously realize the conduction channel construction and defect control. On one hand, the promoted carrier migration makes the electrical conductivity dramatically rise about 7 times, with a maximum power factor of 4.65 μW cm -1 K -2 . Meanwhile, the defect formation mechanism in the screen-printed Bi 2 Te 3 film after the introduction of Te-NS is also in-depth studied, and the bipolar conduction is reduced by increased generation of Te Bi • and/or more suppression of Bi Te ' , resulting in a postponed temperature of the maximum Seebeck coefficient. Hence, the large engineering power factor is achieved with excellent temperature linearity, indicating a possibility of screen-printed film application in a large temperature region. A TE device with a single leg has been fabricated to further demonstrate the generation validity. An open-circuit voltage of 11.34 mV and a maximum output power of 27.1 μW at a temperature gradient of 105 K have been achieved over a wide temperature range from 303 to 478 K. This study provides a theoretical and practical basis for the performance improvement of screen-printed TE films and devices.