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BACKGROUND In recent years, neoadjuvant chemotherapy (NAC) has been increasingly used in patients with resectable colorectal liver metastases. However, the efficacy and safety of NAC in the treatment of resectable colorectal liver metastases (CRLM) are still controversial. AIM To assess the efficacy and application value of NAC in patients with resectable CRLM. METHODS We searched PubMed, Embase, Web of Science, and the Cochrane Library from inception to December 2020 to collect clinical studies comparing NAC with non-NAC. Data processing and statistical analyses were performed using Stata V.15.0 and Review Manager 5.0 software. RESULTS In total, 32 studies involving 11236 patients were included in this analysis. We divided the patients into two groups, the NAC group (that received neoadjuvant chemotherapy) and the non-NAC group (that received no neoadjuvant chemotherapy). The meta-analysis outcome showed a statistically significant difference in the 5-year overall survival and 5-year disease-free survival between the two groups. The hazard ratio (HR) and 95% confidence interval (CI) were HR = 0.49, 95%CI: 0.39-0.61, P = 0.000 and HR = 0.48 95%CI: 0.36-0.63, P = 0.000. The duration of surgery in the NAC group was longer than that of the non-NAC group [standardized mean difference (SMD) = 0.41, 95%CI: 0.01-0.82, P = 0.044)]. The meta-analysis showed that the number of liver metastases in the NAC group was significantly higher than that in the non-NAC group (SMD = 0.73, 95%CI: 0.02-1.43, P = 0.043). The lymph node metastasis in the NAC group was significantly higher than that in the non-NAC group (SMD = 1.24, 95%CI: 1.07-1.43, P = 0.004). CONCLUSION We found that NAC could improve the long-term prognosis of patients with resectable CRLM. At the same time, the NAC group did not increase the risk of any adverse event compared to the non-NAC group.

Wind resource assessment has important economic and ecological implications. Many developing countries in arid and semiarid areas are caught in a dilemma between the development of wind energy and the threat of sandy desertification. Sand-driving winds are momentous for both generating wind energy and aeolian research. The estimation for the probability of sand-driving winds has been rarely studied. The ability of the two-parameter Weibull distribution to estimate high wind velocities is questioned and parameters appear to have no practical significance. Drift potential (DP) is a way of evaluating potential sand transport volume by sand-driving winds, but the relationship between DP and the wind energy of sand-driving winds has been rarely studied. In this paper, a function was constructed from the expressions of DP and the two-parameter Weibull probability distribution to improve the estimation of sand-driving winds. This is simple and applicable to arid and semiarid areas worldwide. The mean wind velocity and the mean wind power density at a height of 10 m around the Badain Jaran Sand Sea in China, are in the range between 2.64 and 4.79 m·s−1, and 27.61–165.61 W·m−2, respectively. The mean wind power density of sand-driving winds accounted for half or more of the total mean wind power density. The relationship among DP, the wind power density of sand-driving winds and the probability of sand-driving winds, was proved theoretically. Gentle winds and strong winds are distinguished by the drift wind velocity at which potential sand transport activities (potential lost wind power density) reach their maximum. The scale parameter dominates the mean and median wind velocity, and represents the effect of convection. The shape parameter characterizes the atmospheric stability. These results provide a basis for the wind energy development, improve the understanding of aeolian activities, and have implications for sand control engineering.

Some of the surface on Earth, Mars, Venus, and Titan is covered by ripples, dunes, and other features formed by sand-driving winds. Many developing countries in arid and semiarid areas are caught in a dilemma between the threat of sandy desertification and the development of wind energy. The estimation for the probability of sand-driving winds has been rarely studied. The ability of two-parameter Weibull probability distribution to estimate sand-driving winds is questioned. Sand transport rate is used only for the evaluation of short-term aeolian activities. Drift potential (DP) is an accessible way of evaluating potential sand transport volume by sand-driving winds. However, the relationship among annual sand transport volume, DP and wind energy has been rarely studied. Sand-driving winds can be divided into gentle winds and strong winds, but it is hard to distinguish them and to quantify their effects on aeolian geomorphology. A function was constructed from expressions of sand transport rate and the two-parameter Weibull probability distribution to improve the estimation of sand-driving winds. On this basis, annual sand transport volume was accurately evaluated by sand-driving winds. This is applicable to arid and semiarid areas worldwide. The relationship among annual sand transport volume, DP and wind energy was analyzed from the perspective of dimensional analysis. Gentle winds and strong winds are distinguished by transport wind velocity at which aeolian activities on a sandy underlying surface reach the erosion–deposition balance, and which corresponds to annual maximum sand transport rate. On a sandy underlying surface strong winds control deposition, while gentle winds dominate wind erosion. The transport wind velocity is nearly constant, weakly related to the probability distribution of sand-driving winds. These results provide a basis for an improved understanding of aeolian activities as an important planetary surface process, sand control engineering, and wind energy development.

In order to meet the demand of remote monitoring, this paper introduces a method of realizing remote monitoring based on mobile network and embedded system. Related key technologies include building remote monitoring terminal, sending and receiving of SMS, making and sending of MMS. By using S3C6410 hardware platform and Linux OS, as well as GPRS module, and developing phone specific program and interface in control terminal. Users can control and monitor the equipments and working condition in remote terminal or dangerous areas, and query their video images and abnormity information by sending phone SMS or clicking on developed phone interface buttons easily and conveniently.

As an emerging two-dimensional (2D) material, monolayer molybdenum disulfide films show excellent electrical and optical properties and have aroused great interest due to their potential applications in electronics and optoelectronics. In this paper, we review our works about molybdenum disulfide films in the past few years. Chemical vapor deposition (CVD) is a convenient and low-cost method to synthesize 2D materials. By oxygen-assisted CVD, the wafer-scale highly-oriented monolayer molybdenum disulfide films and large single-crystal monolayer molybdenum disulfide on various substrates have been prepared epitaxially. Preparation of high-quality monolayer molybdenum disulfide films is the key to measure its intrinsic properties and realize its large-scale applications. Besides the preparation of high-quality materials, the optimizing of transfer technique and fabrication technique are of equal importance for improving the properties of electronic and optoelectronic devices. Water-assisted lossless transfer, patterned peeling, structural change and local phase transition of monolayer molybdenum disulfide films pave the way for preparing and optimizing the functionalized devices. For example, water-assisted transfer and patterned peeling provide methods of preparing molybdenum disulfide samples with clean surfaces and interfaces. Phase transition in the contact area of field-effect transistor reduces the contact resistance effectively, which improves the electrical performance. In addition, the heterojunctions of molybdenum disulfide and other 2D materials show novel electrical and optical properties. As for the functional devices, ultrashort-channel field-effect transistors, integrated flexible thin film transistors, and humidity sensor array have been realized with monolayer molybdenum disulfide films. A grain boundary widening technique is developed to fabricate graphene electrodes for ultrashort-channel monolayer molybdenum disulfide transistors. Field-effect transistors with channel lengths scaling down to 4 nm can be realized reliably and exhibit superior performances, such as the nearly Ohmic contacts and excellent immunity to short channel effects. Furthermore, monolayer molybdenum disulfide films show excellent electrical properties in the measurement of integrated flexible thin film transistors. Under a uniaxial stain of 1%, the performance of the device shows no obvious change, revealing not only the high quality of CVD-grown molybdenum disulfide films, but also the stabilities of these flexible thin film transistor devices. Molybdenum disulfide humidity sensor array for noncontact sensation also shows high sensitivity and stability. Mobility and on/off ratio of the devices in the array decrease linearly with the relative humidity increasing, leading to a high sensitivity of more than 104. The study of monolayer molybdenum disulfide films is universal and instructive for other 2D transition metal dichalcogenides.

With the rapid development of wireless network, demand for the spectrum accessing increases dramatically. However, if selfish users can access the spectrum arbitrarily, it may lead to serious interference problem for the network. In our paper, the spectrum owner in the network regulates the spectrum accessing of radio devices. It uses a new kind of auction called VARYVER to efficiently allocate the channels. We prove that VARYVER auction not only guarantee the truthfulness but also does well in ensuring the fairness among nodes in our multi-hop, multi-channel network. Spectrum owner first determines the winners of the auction, then uses some algorithms to determine the users of the channel based on the information VARYVER collect. Finally, spectrum owner charges the users and redistribute the revenue of the network to both winners and users. Simulation results show that our LP Algorithm does well in both maximizing the throughput of our network and ensuring the fairness among nodes while the Greedy Algorithm may cause data congestion in multi-hop network.