Tillage layer thickness (TLT) of farmland could be regarded as one of physical indexes in assessing soil productivity and quality. In recent years, tillage layer shallowing was found in China in ...various regions, mainly due to the adoption of non-tillage or rotary tillage practices, but only little rough and non-quantitative information is available so far on the issue. This research took Anhui, a typical agricultural province in Eastern China as an example and compared the TLTs of 87 typical profiles on provincial scale and 210 on county scale from 1980s to 2010s. The results showed that TLTs of 3.7% and 17.2% of samples in 1980s and 2010s respectively were larger than 20 cm. From 1980s to 2010s the mean TLT increased from 16.3 cm to 17.4 cm on the provincial scale and from 15.0 cm to 15.5 cm on the county scale respectively.
Anisotropy in electronic structures may ignite intriguing anisotropic optical responses, as has been well demonstrated in various systems including superconductors, semiconductors, and even ...topological Weyl semimetals. Meanwhile, it is well established in metal optics that the metal reflectance declines from one to zero when the photon frequency is above the plasma frequency {\omega}p , behaving as a plasma mirror. However, the exploration of anisotropic plasma mirrors and corresponding applications remains elusive, especially at room temperature. Here, we discover a pronounced anisotropic plasma reflectance edge in the type-II Weyl semimetal WP2, with an anisotropy ratio of {\omega}p up to 1.5. Such anisotropic plasma mirror behavior and its robustness against temperature promise optical device applications over a wide temperature range. For example, the high sensitivity of polarization-resolved plasma reflectance edge renders WP2 an inherent polarization detector. We further achieve a room-temperature WP2-based optical switch, effectively controlled by simply tuning the light polarization. These findings extend the frontiers of metal optics as a discipline and promise the design of multifunctional devices combining both topological and optical features.
Weyl semimetal emerges as a new topologically nontrivial phase of matter, hosting low-energy excitations of massless Weyl fermions. Here, we present a comprehensive study of the type-II Weyl ...semimetal WP2. Transport studies show a butterfly-like magnetoresistance at low temperature, reflecting the anisotropy of the electron Fermi surfaces. The four-lobed feature gradually evolves into a two-lobed one upon increasing temperature, mainly due to the reduced relative contribution of electron Fermi surfaces compared to hole Fermi surfaces for the magnetoresistance. Moreover, angle-dependent Berry phase is further discovered from the quantum oscillations, which is ascribed to the effective manipulation of the extremal Fermi orbits by the magnetic field to feel the nearby topological singularities in the momentum space. The revealed topological characters and anisotropic Fermi surfaces of WP2 substantially enrich the physical properties of Weyl semimetals and hold great promises in topological electronic and Fermitronic device applications.
Tiled modular 2D ultrasound arrays have the potential for realizing large apertures for novel diagnostic applications. Here we present the results of recent work for fabrication of a tileable 2D ...array module implemented using a 1-3 composite of high bandwidth PIN-PMN-PT material closely coupled with high voltage CMOS ASICs for buffering and multiplexing functions. The 2D transducer array is supported by a 3D printed conducting and acoustically attenuating interposer backing which links the array to a PCB housing the interface ASICs. A novel low temperature approach for assembly of the acoustic modules to the printed circuit board utilizing conductive adhesive is presented. The fabricated module consists of an array of 6 × 20 elements at 600 \mu\mathbf{m} pitch in azimuth, and 1600 \mu\mathbf{m} pitch in elevation. The combined acoustic electric assembly displayed excellent overall fractional bandwidth of 81% for the functional elements, high element yield of 93%, and had a center frequency of 3.5 MHz, and −20dB pulse length of 850 ns. The device was interfaced to a Verasonics Vantage 128 ultrasound system using an FPGA controller, and images were acquired using an industry standard tissue mimicking phantom.
碩士
元培科技大學
生物技術研究所
98
Cellulosic biomass from agricultural wastes has been considered as an attractive route for ethanol production. However, cellulosic biomass for ethanol production needs ...pretreatments via liquefaction and saccharification. The aim of this research was to study the optimal conditions for reducing sugar production by acid/autoclaving pretreatment and hydrolysis of corncob material with Streptomyces culture, and the yields of ethanol from fermentation of cellulosic hydrolysate. After corncob was pretreated with 0.5% (v/v) sulfuric acid and autoclaved at 121℃ for 60 min, the cellulosic residue was then hydrolyzed by commercial cellulase, 0.9 g/g dried substrate of total reducing sugar was produced. However, the hydrolysates from autoclaving pretreated corncob material could be converted to maximal yields of reducing sugar when Streptomyces were cultured. Total reducing sugar concentration reached 5.3 g/g dried substrate after Streptomyces sp. was incubated. During the cultivation CMCase, Avicel
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