An efficient way to reduce the power consumption of electronic devices is to lower the supply voltage, but this voltage is restricted by the thermionic limit of subthreshold swing (SS), 60 millivolts ...per decade, in field-effect transistors (FETs). We show that a graphene Dirac source (DS) with a much narrower electron density distribution around the Fermi level than that of conventional FETs can lower SS. A DS-FET with a carbon nanotube channel provided an average SS of 40 millivolts per decade over four decades of current at room temperature and high device current
of up to 40 microamperes per micrometer at 60 millivolts per decade. When compared with state-of-the-art silicon 14-nanometer node FETs, a similar on-state current
is realized but at a much lower supply voltage of 0.5 volts (versus 0.7 volts for silicon) and a much steeper SS below 35 millivolts per decade in the off-state.
Infrared ship target detection is crucial technology in marine scenarios. Ship targets vary in scale throughout navigation because the distance between the ship and the infrared camera is constantly ...changing. Furthermore, complex backgrounds, such as sea clutter, can cause significant interference during detection tasks. In this paper, multiscale morphological reconstruction-based saliency mapping, combined with a two-branch compensation strategy (MMRSM-TBC) algorithm, is proposed for the detection of ship targets of various sizes and against complex backgrounds. First, a multiscale morphological reconstruction method is proposed to enhance the ship targets in the infrared image and suppress any irrelevant background. Then, by introducing a structure tensor with two feature-based filter templates, we utilize the contour information of the ship targets and further improve their intensities in the saliency map. After that, a two-branch compensation strategy is proposed, due to the uneven distribution of image grayscale. Finally, the target is extracted using an adaptive threshold. The experimental results fully show that our proposed algorithm achieves strong performance in the detection of different-sized ship targets and has a higher accuracy than other existing methods.
Tidal bore impact can be strong and destructive, placing estuarine infrastructures under great threat. However, there is a lack of research focusing on accurately estimating the impact pressure ...exerted by tidal bores. Herein new experiments were conducted to investigate the pressure of tidal bore fronts in a glass flume. Through analysis of instantaneous pressure of three forms of tidal bore, it was observed that the pressure fluctuation of weak and strong breaking bore fronts is characterized by impact pressure. The vertical distribution and maximum impact pressure of tidal bore were studied.The maximum impact pressure of breaking bore fronts appeared around 0.46 times height of it. The relationship between relative impact pressure and height of the tidal bore fronts was found to closely follow a normal probability density function. Through nonlinear regression analysis, an empirical equation was derived to calculate impact pressure, which was validated using observation data from the Qiantang River in China. This equation can be utilized to predict the impact pressure of tidal bore fronts and provide valuable support for estuarine engineering design.
Multi-exciton generation-the creation of multiple charge carrier pairs from a single photon-has been reported for several materials and may dramatically increase solar cell efficiency. Singlet ...fission, its molecular analogue, may govern multi-exciton generation in a variety of materials, but a fundamental mechanism for singlet fission has yet to be described. Here, we use sophisticated ab initio calculations to show that singlet fission in pentacene proceeds through rapid internal conversion of the photoexcited state into a dark state of multi-exciton character that efficiently splits into two triplets. We show that singlet fission to produce a pair of triplet excitons must involve an intermediate state that (i) has a multi-exciton character, (ii) is energetically accessible from the optically allowed excited state, and (iii) efficiently dissociates into multiple electron-hole pairs. The rational design of photovoltaic materials that make use of singlet fission will require similar ab initio analysis of multi-exciton states such as the dark state studied here.
Microtia is a congenital external ear malformation that can seriously influence the psychological and physiological well-being of affected children. The successful regeneration of human ear-shaped ...cartilage using a tissue engineering approach in a nude mouse represents a promising approach for auricular reconstruction. However, owing to technical issues in cell source, shape control, mechanical strength, biosafety, and long-term stability of the regenerated cartilage, human tissue engineered ear-shaped cartilage is yet to be applied clinically. Using expanded microtia chondrocytes, compound biodegradable scaffold, and in vitro culture technique, we engineered patient-specific ear-shaped cartilage in vitro. Moreover, the cartilage was used for auricle reconstruction of five microtia patients and achieved satisfactory aesthetical outcome with mature cartilage formation during 2.5years follow-up in the first conducted case. Different surgical procedures were also employed to find the optimal approach for handling tissue engineered grafts. In conclusion, the results represent a significant breakthrough in clinical translation of tissue engineered human ear-shaped cartilage given the established in vitro engineering technique and suitable surgical procedure.
This study was registered in Chinese Clinical Trial Registry (ChiCTR-ICN-14005469).
•Patient-specific ear-shaped cartilage was engineered in vitro using expanded MCs and compound biodegradable scaffold.•The first microtia case treated with the tissue engineered ear-shaped cartilage was follow-up for 2.5years.•Other four cases with similar and different surgical procedures were also presented.
Microtia is a congenital external ear malformation that can seriously influence the psychological and physiological well-being of affected children. Using expanded microtia chondrocytes, compound biodegradable scaffold, and in vitro culture technique, we engineered patient-specific ear-shaped cartilage in vitro, and performed a pilot clinical trial of auricle reconstruction using the engineered ear cartilage on five patients. Satisfactory aesthetical outcome with mature cartilage formation was achieved with the longest follow-up of 2.5years.
The Iranian plateau has a more straightforward relationship between the Paleo-Tethys and Neo-Tethys, than other regions in the Tethyan realm and is an ideal place to test the genetic connection of ...how the Paleo-Tethys affected the Neo-Tethys. Moreover, there is no consensus on how Paleo-Tethyan evolution influenced the Neo-Tethyan Wilson cycle. We studied the petrology, geochemistry, and metamorphic age of an eclogite suite at Rasht in northern Iran from the Paleo-Tethyan suture. The eclogitic protolith was a typical mid-ocean-ridge basalt and achieved its peak metamorphic condition of 2.7 GPa and 590 °C at 353 ± 8.9 Ma. Reconstructed pressure-temperature-time path of the eclogite-facies rocks suggests that the eclogitic protolith entered the trench at 356 ± 8.9 Ma. Mid-oceanic ridge rocks formed at ~380 Ma at the Rasht region and other places along the Alborz Mountain strike. A ~ 25 million years (Myr) period from the birth of oceanic crust to subduction at Rasht region implies that the mid-ocean-ridge was close to the trench. We propose that the Paleo-Tethyan mid-ocean-ridge was trench-parallelly subducted beneath the Eurasian boundary in northern Iran. This ridge-subduction propagated from east to west between 380 and 355 Ma. 47–27 Myr after ridge consumption, subduction of the remaining Paleo-Tethyan oceanic crust exerted a continuous extensional stress of ~0.1 GPa on the passive margin of Gondwana since the late Carboniferous. The drag-force eventually detached the Central Iranian Block from Gondwana, and opened the Neo-Tethyan ocean during the middle-late Permian.
We report an efficient electrochemical conversion of CO2 to CO on surface-activated bismuth nanoparticles (NPs) in acetonitrile (MeCN) under ambient conditions, with the assistance of ...1-butyl-3-methylimidazolium trifluoromethanesulfonate (bmimOTf). Through the comparison between electrodeposited Bi films (Bi-ED) and different types of Bi NPs, we, for the first time, demonstrate the effects of catalyst’s size and surface condition on organic phase electrochemical CO2 reduction. Our study reveals that the surface inhibiting layer (hydrophobic surfactants and Bi3+ species) formed during the synthesis and purification process hinders the CO2 reduction, leading to a 20% drop in Faradaic efficiency for CO evolution (FECO). Bi particle size showed a significant effect on FECO when the surface of Bi was air-oxidized, but this effect of size on FECO became negligible on surface-activated Bi NPs. After the surface activation (hydrazine treatment) that effectively removed the native inhibiting layer, activated 36-nm Bi NPs exhibited an almost-quantitative conversion of CO2 to CO (96.1% FECO), and a mass activity for CO evolution (MACO) of 15.6 mA mg–1, which is three-fold higher than the conventional Bi-ED, at −2.0 V (vs Ag/AgCl). This work elucidates the importance of the surface activation for an efficient electrochemical CO2 conversion on metal NPs and paves the way for understanding the CO2 electrochemical reduction mechanism in nonaqueous media.
Top-gated p-type field-effect transistors (FETs) have been fabricated in batch based on carbon nanotube (CNT) network thin films prepared from CNT solution and present high yield and highly uniform ...performance with small threshold voltage distribution with standard deviation of 34 mV. According to the property of FETs, various logical and arithmetical gates, shifters, and d-latch circuits were designed and demonstrated with rail-to-rail output. In particular, a 4-bit adder consisting of 140 p-type CNT FETs was demonstrated with higher packing density and lower supply voltage than other published integrated circuits based on CNT films, which indicates that CNT based integrated circuits can reach to medium scale. In addition, a 2-bit multiplier has been realized for the first time. Benefitted from the high uniformity and suitable threshold voltage of CNT FETs, all of the fabricated circuits based on CNT FETs can be driven by a single voltage as small as 2 V.
•Simultaneously determining difenoconazole and propiconazole in wheat and soil.•Half-lives in ecosystem were relatively short, ca. 3–9days.•The residues in wheat grain were below 0.01mg/kg based on ...use labels.•The residues in wheat are safe per established MRL’s.
An analytical method for simultaneously determining the residues of difenoconazole and propiconazole in wheat straw, wheat grain and soil was developed. Mean recoveries and relative standard deviations in all samples ranged 86.2–101.3% and 3.1–12.1% for propiconazole and difenoconazole. The half-lives of difenoconazole and propiconazole were 3.6–5.5days and 5.1–6.9days in wheat straws, and 4.9–5.8days and 6.1–8.4days in soil, respectively. The residues in wheat grain were found to be <0.01mg/kg, based on the application rate (135g a.i./ha) and the pre-harvest interval (PHI=28days) recommended by the manufacturer. The results suggest that the use of difenoconazole and propiconazole on wheat is considered to be safe under the Good Agricultural Practices (GAP) in the Chinese fields, and the main factors for pesticide residue in crops are application times, rates and pre-harvest intervals.
Large-area monolayer WS2 is a desirable material for applications in next-generation electronics and optoelectronics. However, the chemical vapour deposition (CVD) with rigid and inert substrates for ...large-area sample growth suffers from a non-uniform number of layers, small domain size and many defects, and is not compatible with the fabrication process of flexible devices. Here we report the self-limited catalytic surface growth of uniform monolayer WS2 single crystals of millimetre size and large-area films by ambient-pressure CVD on Au. The weak interaction between the WS2 and Au enables the intact transfer of the monolayers to arbitrary substrates using the electrochemical bubbling method without sacrificing Au. The WS2 shows high crystal quality and optical and electrical properties comparable or superior to mechanically exfoliated samples. We also demonstrate the roll-to-roll/bubbling production of large-area flexible films of uniform monolayer, double-layer WS2 and WS2/graphene heterostructures, and batch fabrication of large-area flexible monolayer WS2 film transistor arrays.
PDF
