Highly efficient triazine/carbazole-based host material for green phosphorescent organic light-emitting diodes with low efficiency roll-off

Two novel triazin/carbazole-based host materials were designed and synthesized, which demonstrated outstanding EL performance with maximum CE, PE and EQE of 69.3 cd A−1, 54.2 lm W−1 and 21.9%, respectively.</p

Optimization on the jet characteristics of the main nozzle of hot-blowing snow removal device

The exhaust devices used by snow removal vehicles are mainly based on hot-blowing snow removal. Due to the inherent characteristics of the turbojet engine such as low flow rate and high exhaust temperature, the modified hot-blowing snow removal device has problems of low snow removal efficiency and the possibility of ablation and damage to the road surface. In order to solve the problem, transforming the turbofan engine with a high flow rate and a low exhaust temperature into a hot-blowing snow removal device is an important improvement to achieve efficient and safe snow removal operations. In order to convert a medium bypass ratio turbofan engine into a hot-blowing snow removal device, the computational fluid dynamics (CFD) software CFX was used to analyze the internal and external flow field characteristics of the main nozzle of an exhaust device under the 60 % rated condition of the engine. The effective area sizes of the jet velocity and temperature predicted by the external flow field were used to optimize the layout of the main nozzle

Electrochemical Conversion of Methane to Ethylene in a Solid Oxide Electrolyer

Conversion of methane to ethylene with high yield remains a fundamental challenge due to the low ethylene selectivity, severe carbon deposition and instability of catalysts. Here we demonstrate a conceptually different process of in situ electrochemical oxidation of methane to ethylene in a solid oxide electrolyzer under ambient pressure at 850 °C. The porous electrode scaffold with an in situ-grown metal/oxide interface enhances coking resistance and catalyst stability at high temperatures. The highest C2 product selectivity of 81.2% together with the highest C2 product concentration of 16.7% in output gas (12.1% ethylene and 4.6% ethane) is achieved while the methane conversion reaches as high as 41% in the initial pass. This strategy provides an optimal performance with no obvious degradation being observed after 100 h of high temperature operation and 10 redox cycles, suggesting a reliable electrochemical process for conversion of methane into valuable chemicals

Polymorphisms in thymidylate synthase gene and susceptibility to breast cancer in a Chinese population: a case-control analysis

BACKGROUND: Accumulative evidence suggests that low folate intake is associated with increased risk of breast cancer. Polymorphisms in genes involved in folate metabolism may influence DNA methylation, nucleotide synthesis, and thus individual susceptibility to cancer. Thymidylate synthase (TYMS) is a key enzyme that participates in folate metabolism and catalyzes the conversion of dUMP to dTMP in the process of DNA synthesis. Two potentially functional polymorphisms [a 28-bp tandem repeat in the TYMS 5'-untranslated enhanced region (TSER) and a 6-bp deletion/insertion in the TYMS 3'-untranslated region (TS 3'-UTR)] were suggested to be correlated with alteration of thymidylate synthase expression and associated with cancer risk. METHODS: To test the hypothesis that polymorphisms of the TYMS gene are associated with risk of breast cancer, we genotyped these two polymorphisms in a case-control study of 432 incident cases with invasive breast cancer and 473 cancer-free controls in a Chinese population. RESULTS: We found that the distribution of TS3'-UTR (1494del6) genotype frequencies were significantly different between the cases and controls (P = 0.026). Compared with the TS3'-UTR del6/del6 wild-type genotype, a significantly reduced risk was associated with the ins6/ins6 homozygous variant genotype (adjusted OR = 0.58, 95% CI = 0.35–0.97) but not the del6/ins6 genotype (OR = 1.09, 95% CI = 0.82–1.46). Furthermore, breast cancer risks associated with the TS3'-UTR del6/del6 genotype were more evident in older women, postmenopausal subjects, individuals with a younger age at first-live birth and individuals with an older age at menarche. However, there was no evidence for an association between the TSER polymorphism and breast cancer risks. CONCLUSION: These findings suggest that the TS3'-UTR del6 polymorphism may play a role in the etiology of breast cancer. Further larger population-based studies as well as functional evaluation of the variants are warranted to confirm our findings

Corneal Surface Ablation Laser Refractive Surgery for the Correction of Myopia: A Network Meta-analysis

PURPOSE: To systematically compare the efficacy, predictability, safety, postoperative haze, pain scores, and epithelial healing time of four corneal surface ablation procedures. METHODS: PubMed, Embase, Cochrane Library, and the U.S. trial registry were searched up to June 2018. Randomized controlled trials were selected. Efficacy (uncorrected distance visual acuity of 20/20 or better), predictability (refractive spherical equivalent within ±0.50 diopters [D] of the target), and safety (loss of two or more lines of spectacle corrected distance visual acuity) were set as primary outcome measures. Haze, pain scores, and epithelial healing time were set as secondary outcome measures. RESULTS: Eighteen studies involving 1,423 eyes were included. According to the Grading of Recommendations Assessment, Development, and Evaluation, the quality of outcomes were moderate to high (70.6%). There were no differences in efficacy, predictability, safety, haze, day 1 pain, and epithelial healing time between treatments. Epithelial laser in situ keratomileusis (epi-LASIK) had statistically significantly higher pain scores on day 3 compared to photorefractive keratectomy (PRK) (weighted mean differences [WMD] = 2.2, 95% credible intervals [CrI] = 0.19 to 4.01) and transepithelial PRK (T-PRK) (WMD = 2.7, 95% CrI = 0.51 to 4.84). The surface under the cumulative ranking curve ranking results (best to worst) showed laser epithelial keratomileusis (LASEK) ranked highest for efficacy, predictability, safety, and day 1 pain scores. Epi-LASIK ranked best for grade 1 haze scores. T-PRK ranked best for haze of 0.5 or higher, haze scores day 3 pain scores, and epithelial healing time. CONCLUSIONS: Surface laser refractive surgeries are comparable in terms of efficacy, predictability, safety, and postoperative haze except for day 3 pain scores, with epi-LASIK being more painful compared to PRK and T-PRK. [J Refract Surg. 2018;34(11):726-735.]

Cross-cultural validation of the functional vision questionnaire for children and young people (FVQ_CYP) with visual impairment in the Dutch population: challenges and opportunities

BACKGROUND:To assess cross-cultural validity between Dutch and English versions of the FVQ_CYP, a patient-reported outcome measure developed in the United Kingdom (UK) for children and adolescents with (severe) visual impairment or blindness (VI for brevity) to measure functional vision. METHODS:The 36-item FVQ_CYP was translated and adapted into Dutch using standard guidelines. The questionnaire was administered to Dutch children and adolescents aged 7-17 years (N = 253) with impaired vision (no restrictions regarding acuity). Data were compared to existing UK data of children and adolescents aged 10-15 years (N = 91) with VI (acuity LogMar worse than 0.48). As with the original UK FVQ_CYP validation, a rating scale model (RSM) was applied to the Dutch data. RESULTS:Minor adaptations were needed in translation-rounds. Significant differences in item responses were found between the Dutch and UK data. Item response theory assumptions were met, but fit to the RSM was unsatisfactory. Therefore, psychometric properties of the Dutch FVQ_CYP were analysed irrespective of the original model and criteria used. A graded response model led to the removal of 12 items due to missing data, low information, overlapping content and limited relevance to Dutch children. Fit indices for the remaining 24 items were adequate. CONCLUSIONS:Differences in population characteristics, distribution of responses, non-invariance at the model level and small sample sizes challenged the cross-cultural validation process. However, the Dutch adapted FVQ_CYP showed high measurement precision and broad coverage of items measuring children's functional vision. The underlying reasons for differences between countries in instrument performance are discussed with implications for future studies

Voice detection with spiking neural network for smart sensor applications

A novel methodology that embeds machine learning algorithm on microcontrollers for real time training and processing, or in other words, online training on edge devices is described in this report. Due to memory limitation and single time dimensional processing of microcontroller unit (MCU), the Arduino Uno and Nano are engaged in this project. With that, traditional Artificial Intelligence (AI) algorithms were modified to suit the new working environment. Firstly, an improved Spiking Recurrent Neural Network (SRNN) based on Spiking Convolutional Neural Network (SCNN) is designed to realize better real time voice signal, and an accuracy of 99.8% in voice digit recognition on Matlab software platform was achieved. However, Long Short-Term Memory (LSTM) Neural Network in SRNN trained all weights in floating 32-bit applications. Thus, for hardware convenience, a dynamic bias and advanced processing LSTM is designed and tested in floating 32-bit, fixed 1-bit and fixed 2-bit system, each achieved final loss of 0.0425, 0.0446 and 0.0453 in mean square error (MSE), respectively. Not only software programming was innovated in this project, hardware implementation had also been realized using different components. A multi-layer perceptron neural network that deployed 16% of the Arduino Uno flash memory was established to recognize a 7-segment LED displayer, and finally achieved a mere 0.0004 error, thus verified that simple neural network can built on an ATMEGA328P processor, an 8-bit AVR microcontroller with 32K Bytes in-system programmable flash memory. Moreover, a voice command recognition had been achieved 97.5% accuracy based on pre-well-trained neural network and Fast Fourier Transform (FFT) in a TensorFlow microprocessor library. Finally, a single spike neuron was simulated by one Arduino Uno board to mimic neuron’s performance under different cell state surroundings. Also, A simple Spiking Neural Network (SNN) made up by two series connected spike neurons, where each neuron was represented by an Arduino Uno board, was able to reproduce the excitation wave of series spiking neurons, All experiments in this final year project had verified that the proposed SNN for smart sensor applications is an interesting and valuable topic worth continuing for online training on edge devices.Bachelor of Engineering (Electrical and Electronic Engineering

Speed Control Effect Study on Optical Illusion Deceleration Markings

The optical illusion deceleration marking is one of the commonly used speed control measures. In this research, the authors analyzed operating speed and trajectory of motor vehicle at intersection where optical illusion deceleration marking is installed. Quantitative and qualitative evaluation on effect of optical illusion deceleration marking is conducted. Results showed that optical illusion deceleration marking would help to reduce operating speed and average speed by 5-10km/h, to regulate motorcycle driver behavior, and to reduce speed difference, so that driving safety is ensured. Optical illusion deceleration marking is suitable for accident prone road sections on two-lane highways which main vehicle types are passenger car and motorcycle

Severe Traffic Crash Speaks : Safety Facts From Mountain Roads in China

objective to build up a systematic mountain road safety enhancement technology, this study analyses severe traffic crashes from 2006 to 2010 occurred on an inter-regional mountain arterial road network in south China. In order to digest these crash data collected from local traffic police stations, the authors conduct the in-depth crash analysis from the aspect of human, vehicle, road, and management. By developing the definition sets for crash deterministic causing factors judging system, the deterministic causes of severe accidents on mountain roads in China are deeply investigated. Results of our analysis indicate that human factor does weigh the most in the occurrence of the severe crashes; main crash types on mountain roads are running-off road, headon collision, overturned; Almost 76% severe crashes occurred on slope/curve combination sites; and freight car shall be given more attentions in reducing the severe accidents

Effects of Roadway Segment Alignments and Locations on Rural Two-Lane Highway Crash Rates

This paper investigates the effects of road segment alignment and location on rural two-lane highway crash rates by taking the mileage of segment types into consideration. Roadway segments are classified and redefined according to the segment alignment and location. The definitions of crash rates in terms of segment alignment and location are presented respectively. The study gathers crash data and the roadway geometric information of rural two-lane highways in southwest of China and crash rates of each segment type are proposed by utilizing the proposed definitions. The result indicates that gentle-slope &amp; sharp-curve segments and intersections tend to have extremely higher crash rates than the other types of segments