Integrated molecular diode as 10 MHz half-wave rectifier based on an organic nanostructure heterojunction

Considerable efforts have been made to realize nanoscale diodes based on single molecules or molecular ensembles for implementing the concept of molecular electronics. However, so far, functional molecular diodes have only been demonstrated in the very low alternating current frequency regime, which is partially due to their extremely low conductance and the poor degree of device integration. Here, we report about fully integrated rectifiers with microtubular soft-contacts, which are based on a molecularly thin organic heterojunction and are able to convert alternating current with a frequency of up to 10 MHz. The unidirectional current behavior of our devices originates mainly from the intrinsically different surfaces of the bottom planar and top microtubular Au electrodes while the excellent high frequency response benefits from the charge accumulation in the phthalocyanine molecular heterojunction, which not only improves the charge injection but also increases the carrier density

Helical Single-Lamellar Crystals Thermotropically Formed in a Synthetic Nonracemic Chiral Main-Chain Polyester

Phase structures and transformation mechanisms of nonracemic chiral biological and synthetic polymers are fundamentally important topics in understanding their macroscopic responses in different environments. It has been known for many years that helical structures and morphologies can exist in low-ordered chiral liquid crystalline (LC) phases. However, when the chiral liquid crystals form highly ordered smectic liquid crystal phases, the helical morphology is suppressed due to the crystallization process. A double-twisted morphology has been observed in many liquid crystalline biopolymers such as dinoflaggellate chromosomes (in Prorocentrum micans) in an in vivo arrangement. Helical crystals grown from solution have been reported in the case of Bombyx mori silk fibroin crystals having the beta modification. This study describes a synthetic nonracemic chiral main-chain LC polyester that is able to thermotropically form helical single lamellar crystals. Flat single lamellar crystals can also be observed under the same crystallization condition. Moreover, flat and helical lamellae can coexist in one single lamellar crystal, within which one form can smoothly transform to the other. Both of these crystals possess the same structure, although translational symmetry is broken in the helical crystals. The polymer chain folding direction in both flat and helical lamellar crystals is determined to be identical, and it is always along the long axis of the lamellae. This finding provides an opportunity to study the chirality effect on phase structure, morphology, and transformation in condensed states of chiral materials. [S0163-1829(99)01042-5]

Double Twist in Helical Polymer Soft Crystals

In natural and synthetic materials having non-racemic chiral centers, chirality and structural ordering each play a distinct role in the formation of ordered states. Configurational chirality can be extended to morphological chirality when the phase, structures possess low liquid crystalline order. In the crystalline states the crystallization process suppresses the chiral helical morphology due to strong ordering interactions, In this Letter, we report the first observation of helical single lamellar crystals of synthetic non-racemic chiral polymers. Experimental evidence shows that the molecular chains twist along both the long and short axes of the helical lamellar crystals, which is the first time a double-twist molecular orientation in a helical crystal has been observed

(Cities and Urban Cultures)

Designed as a text for undergraduate courses in cultural studies, sociology and wider social science, this book traces the development of urban environments from the nineteenth century to the present, and illuminates the nature of urban life

Dexamethasone added to local anesthetics in ultrasound-guided transversus abdominis plain (TAP) block for analgesia after abdominal surgery: A systematic review and meta-analysis of randomized controlled trials.

ObjectiveTo evaluate the analgesic efficacy of dexamethasone added to local anesthetics in ultrasound-guided transversus abdominis plane (TAP) block for the patients after abdominal surgery.MethodsPubMed, CENTRAL, EMBASE, Web of science were searched to identify eligible randomized controlled trials (RCTs) that compared dexamethasone added to local anesthetics in ultrasound-guided TAP block with control for postoperative analgesia in adult patients undergoing abdominal surgery. Primary outcomes included postoperative pain intensity, the time to the first request for additional analgesics, and opioid consumption over 24 h after surgery. Secondary outcome was the incidence of postoperative nausea and vomiting. Analysis was performed by RevMan 5.3 software and the quality of evidence was rated using GRADE (Grading of Recommendations, Assessment, Development and Evaluation) approach.ResultsNine RCTs involving 575 patients were included. Compared to the control, dexamethasone added to local anesthetics in ultrasound-guided TAP block significantly decreased visual analogue scale (VAS) scores at rest at 4h (mean difference [MD] = -1.01; 95% confidence intervals [CI], -1.29 to -0.73; PConclusionsDexamethasone added to local anesthetics in ultrasound-guided TAP block was a safe and effective strategy for postoperative analgesia in adult patients undergoing abdominal surgery

Monitoring of Nitrogen Indices in Wheat Leaves Based on the Integration of Spectral and Canopy Structure Information

Canopy spectral reflectance can indicate both crop nutrient and canopy structural information. Differences in canopy structure can affect spectral reflectance. However, a non-imaging spectrometer cannot distinguish such differences while monitoring crop nutrients, because the results are likely to be influenced by the canopy structure. In addition, nitrogen application rate is one of the main factors influencing the canopy structure of crops. Strong correlations exist between indices of canopy structure and leaf nitrogen, and thus, these can be used to compensate for the spectral monitoring of nitrogen content in wheat leaves. In this study, canopy structural indices (CSI) such as wheat coverage, height, and textural features were obtained based on the RGB and height images obtained by the RGB-D camera. Moreover, canopy spectral reflectance was obtained by an ASD hyperspectral spectrometer, based on which two vegetation indices—ratio vegetation index (RVI) and angular insensitivity vegetation index (AIVI)—were constructed. With the vegetation indices and CSIs as input parameters, a model was established to predict the leaf nitrogen content (LNC) and leaf nitrogen accumulation (LNA) of wheat based on partial least squares (PLS) and random forest (RF) regression algorithms. The results showed that the RF model with RVI and CSI as inputs had the highest prediction accuracy for LNA, the coefficient of determination (R2) reached 0.79, and the root mean square error (RMSE) was 1.54 g/m2. The vegetation indices and coverage were relatively important features in the model. In addition, the PLS model with AIVI and CSI as input parameters had the highest prediction accuracy for LNC, with an R2 of 0.78 and an RMSE of 0.35%, among the vegetation indices. In addition, parts of both the textural and height features were important. The results suggested that PLS and RF regression algorithms can effectively integrate spectral and canopy structural information, and canopy structural information effectively supplement spectral information by improving the prediction accuracy of vegetation indices for LNA and LNC

D (2005b) Probabilistic algorithm to support the fingerprinting method for CDMA location

Abstract. Mobile phone location methods based on signal time delay and angle of arrival measurements, such as time of arrival (TOA), time difference of arrival (TDOA), or angle of arrival (AOA), suffer from the non-line-of-sight (NLOS) error and multipath, especially in urban and suburban areas. On the other hand, the “fingerprinting ” technique utilises location-dependent signals available in mobile phone systems from several transmitters, such as the received signal strength (RSS). The problems in the former methods become useful information in the latter method because local signal behaviour is exploited. Generally, any location-dependent information can be used as the “fingerprint ” to support positioning. The conventional algorithms using RSS in mobile phone positioning are deterministic. However, a probabilistic approach can also be used to estimate the position. This paper discusses the probabilistic approach based on an experiment using a CDMA network. The results show both approaches can provide a good estimate of the mobile user’s (MU) location, with the accuracy of the probabilistic method proving to be better. Keywords. Fingerprinting technique, Bayes' theorem, positionin

A Study of Interpolation Compensation Based Large Step Simulation of PWM Converters

Real-time online simulation based on a real-time workshop (RTW) plays a vital role in the study and application of power electronics. However, restricted by the performance of equipment and hardware, the simulators so far available in the market mainly support simulation steps over 50 μs, while large step simulation may result in the action delay of pulse-width modulating (PWM), numerical oscillation and high-level non-characteristic harmonic distortion. In view of these problems, this paper puts forward a modeling method based on integral prediction and interpolation compensation. First of all, prediction is performed one step in advance by the implicit trapezoidal method to find out the accurate time when the triangle carrier wave intersects with the modulation wave. At the same time, a mathematic model is built for the insulated gate bipolar transistor (IGBT) to output equivalent voltage waveform according to the principle of area equivalent. Next, in MATLAB/Simulink, offline simulation is performed with the three-phase AC-DC-AC converter as the subject. By comparing the control accuracy, the content of harmonic wave and the simulation time, the simulation effects of the 50 μs fixed-step interpolation prediction model are the same as that for a 5 μs fixed-step standard model. Finally, the effectiveness and high efficiency of this algorithm are verified on a real-time simulator, marking the application of offline models on real-time simulators