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Isothermal oxidation behaviour of two nickel base superalloys with different Cr contents was investigated in the temperature range of 700–800 °C. Weight–change curves show that weight loss increases with increasing temperature and a relatively lower Cr ratio corresponds to slow weight gain rate. Microscopic observations uncover that oxidation penetration attacks the alloys primarily along grain boundary especially for the lower-Cr alloy, and the penetration depth is strongly dependent on the oxidation temperature. The underlying oxidation mechanisms of the two alloys are explained using energy-dispersive x-ray spectroscopy and X-ray photoelectron spectroscopy.

Deep learning-based recommender systems (DRSs) are increasingly and widely deployed in the industry, which brings significant convenience to people's daily life in different ways. However, recommender systems are also shown to suffer from multiple issues,e.g., the echo chamber and the Matthew effect, of which the notation of "fairness" plays a core role.While many fairness notations and corresponding fairness testing approaches have been developed for traditional deep classification models, they are essentially hardly applicable to DRSs. One major difficulty is that there still lacks a systematic understanding and mapping between the existing fairness notations and the diverse testing requirements for deep recommender systems, not to mention further testing or debugging activities. To address the gap, we propose FairRec, a unified framework that supports fairness testing of DRSs from multiple customized perspectives, e.g., model utility, item diversity, item popularity, etc. We also propose a novel, efficient search-based testing approach to tackle the new challenge, i.e., double-ended discrete particle swarm optimization (DPSO) algorithm, to effectively search for hidden fairness issues in the form of certain disadvantaged groups from a vast number of candidate groups. Given the testing report, by adopting a simple re-ranking mitigation strategy on these identified disadvantaged groups, we show that the fairness of DRSs can be significantly improved. We conducted extensive experiments on multiple industry-level DRSs adopted by leading companies. The results confirm that FairRec is effective and efficient in identifying the deeply hidden fairness issues, e.g., achieving 95% testing accuracy with half to 1/8 time.

Objectives: We studied the consequences of parental domestic smoking behavior on children’s digital entertainment and mental health during COVID-19, and put forward the initiative of family tobacco control toprotect children’s physical and mental health. Methods: From February 20 to February 23, 2021, using Sojump survey method, 800 smoking parents who live with children aged 6∼12 answered the questionnaire online about basic information, children’s digital entertainment status, strengths and difficulties (SDQ). Results: 60.8% of the children exposed to secondhand smoke spend more than 1 h on digital entertainment every day; abnormal detection rates of emotional symptoms, conduct problems, hyperactivity and inattention, peer interaction, pro-social behavior, and difficulty total scores are 29.2%, 38.2%, 6.5%, 80.3%, 22.0%, 40.0%, respectively. Single factor analysis suggests that there are statistical differences in the degree of impact of household monthly income and children’s life under smoking parents on digital entertainment duration (χ= 14.76, 10.88; P

The marine internet of things (MIoT), an increasingly important foundation for ocean development and protection, consists of a variety of marine distributed sensors under water. These sensors of the MIoT have always been highly dependent on batteries. To realize in situ power supply, a flexible seaweed-like triboelectric nanogenerator (S-TENG) capable of harvesting wave energy is proposed in this study. The flexible structure, designed with inspiration from the seaweed structure, processes extensive marine application scenarios. The bending and recovering of the S-TENG structure under wave excitations are converted to electricity. As the output performance increases with the number of parallel connected S-TENG units, an S-TENG system with multiple units could serve for floating buoys, coastal power stations, and even submerged devices. Through the demonstration experiments performed in this study, the flexible, low-cost S-TENG could become an effective approach to achieve a battery independent MIoT.

Endometrial cancer (EC) is the gynecological tumor with the highest incidence. In recent years, it has been proved that necroptosis is a method of cell death related to EC. However, the expression of necroptosis-related miRNA in EC and its correlation with prognosis still ill-defined. Use the Cancer Genome Atlas (TCGA) cohort to obtain prognostic data and related clinical data for ECs and normal endometrium tissues. In this study, we identified three necroptotic regulatory miRNAs that are necroptosis-related and survival-related miRNAs (DENSMs) between normal endometrium tissues and EC from 13 necroptosis-related miRNAs. The three DENSMs signature was built to develop prognostic model and classified all EC patients into a high or low risk group. EC patients in the low-risk group showed significantly higher survival possibilities than those in the high-risk group (p = 0.0242), and the risk score was found to be an independent prognosis factor for predicting the OS of EC patients (p = 0.0254) in multivariate Cox regression. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed dephosphorylation, microtubule, protein serine/threonine kinase activity, PI3K-Akt signaling pathway and MAPK signaling pathway are closely related to it. In conclusion, the risk prediction model based on necroptosis-related miRNAs can effectively predict the prognosis of EC patients.

For the scalability of industrial online advertising systems, a two-stage auction architecture is widely used to enable efficient ad allocation on a large set of corpus within a limited response time. The current deployed two-stage ad auction usually retrieves an ad subset by a coarse ad quality metric in a pre-auction stage, and then determines the auction outcome by a refined metric in the subsequent stage. However, this simple and greedy solution suffers from serious performance degradation, as it regards the decision in each stage separately, leading to an improper ad selection metric for the pre-auction stage. In this work, we explicitly investigate the relation between the coarse and refined ad quality metrics, and design a two-stage ad auction by taking the decision interaction between the two stages into account. We decouple the design of the two-stage auction by solving a stochastic subset selection problem in the pre-auction stage and conducting a general second price (GSP) auction in the second stage. We demonstrate that this decouple still preserves the incentive compatibility of the auction mechanism. As the proposed formulation of the pre-auction stage is an NP-hard problem, we propose a scalable approximation solution by defining a new subset selection metric, namely Pre-Auction Score (PAS). Experiment results on both public and industrial dataset demonstrate the significant improvement on social welfare and revenue of the proposed two-stage ad auction, than the intuitive greedy two-stage auction and other baselines.

Gynostemma longipes contains an abundance of dammarane-type ginsenosides and gypenosides that exhibit extensive pharmacological activities. Increasing attention has been paid to the elucidation of cytochrome P450 monooxygenases (CYPs) and UDP-dependent glycosyltransferases (UGTs) that participate downstream of ginsenoside biosynthesis in the Panax genus. However, information on oxidosqualene cyclases (OSCs), the upstream genes responsible for the biosynthesis of different skeletons of ginsenoside and gypenosides, is rarely reported. Here, an integrative study of the metabolome and the transcriptome in the leaf, stolon, and rattan was conducted and the function of GlOSC1 was demonstrated. In total, 46 triterpenes were detected and found to be highly abundant in the stolon, whereas gene expression analysis indicated that the upstream OSC genes responsible for saponin skeleton biosynthesis were highly expressed in the leaf. These findings indicated that the saponin skeletons were mainly biosynthesized in the leaf by OSCs, and subsequently transferred to the stolon via CYPs and UGTs biosynthesis to form various ginsenoside and gypenosides. Additionally, a new dammarane-II synthase (DDS), GlOSC1, was identified by bioinformatics analysis, yeast expression assay, and enzyme assays. The results of the liquid chromatography–mass spectrometry (LC–MS) analysis proved that GlOSC1 could catalyze 2,3-oxidosqualene to form dammarenediol-II via cyclization. This work uncovered the biosynthetic mechanism of dammarenediol-II, an important starting substrate for ginsenoside and gypenosides biosynthesis, and may achieve the increased yield of valuable ginsenosides and gypenosides produced under excess substrate in a yeast cell factory through synthetic biology strategy.

In online advertising, auto-bidding has become an essential tool for advertisers to optimize their preferred ad performance metrics by simply expressing high-level campaign objectives and constraints. Previous works designed auto-bidding tools from the view of single-agent, without modeling the mutual influence between agents. In this paper, we instead consider this problem from a distributed multi-agent perspective, and propose a general $\underline{M}$ulti-$\underline{A}$gent reinforcement learning framework for $\underline{A}$uto-$\underline{B}$idding, namely MAAB, to learn the auto-bidding strategies. First, we investigate the competition and cooperation relation among auto-bidding agents, and propose a temperature-regularized credit assignment to establish a mixed cooperative-competitive paradigm. By carefully making a competition and cooperation trade-off among agents, we can reach an equilibrium state that guarantees not only individual advertiser's utility but also the system performance (i.e., social welfare). Second, to avoid the potential collusion behaviors of bidding low prices underlying the cooperation, we further propose bar agents to set a personalized bidding bar for each agent, and then alleviate the revenue degradation due to the cooperation. Third, to deploy MAAB in the large-scale advertising system with millions of advertisers, we propose a mean-field approach. By grouping advertisers with the same objective as a mean auto-bidding agent, the interactions among the large-scale advertisers are greatly simplified, making it practical to train MAAB efficiently. Extensive experiments on the offline industrial dataset and Alibaba advertising platform demonstrate that our approach outperforms several baseline methods in terms of social welfare and revenue., Accepted by WSDM 2022

Natural Language Processing (NLP) has been revolutionized by the use of Pre-trained Language Models (PLMs) such as BERT. Despite setting new records in nearly every NLP task, PLMs still face a number of challenges including poor interpretability, weak reasoning capability, and the need for a lot of expensive annotated data when applied to downstream tasks. By integrating external knowledge into PLMs, \textit{\underline{K}nowledge-\underline{E}nhanced \underline{P}re-trained \underline{L}anguage \underline{M}odels} (KEPLMs) have the potential to overcome the above-mentioned limitations. In this paper, we examine KEPLMs systematically through a series of studies. Specifically, we outline the common types and different formats of knowledge to be integrated into KEPLMs, detail the existing methods for building and evaluating KEPLMS, present the applications of KEPLMs in downstream tasks, and discuss the future research directions. Researchers will benefit from this survey by gaining a quick and comprehensive overview of the latest developments in this field., Comment: 19 pages, 12 figures, 192 references

Recent studies show that pre-trained language models (LMs) are vulnerable to textual adversarial attacks. However, existing attack methods either suffer from low attack success rates or fail to search efficiently in the exponentially large perturbation space. We propose an efficient and effective framework SemAttack to generate natural adversarial text by constructing different semantic perturbation functions. In particular, SemAttack optimizes the generated perturbations constrained on generic semantic spaces, including typo space, knowledge space (e.g., WordNet), contextualized semantic space (e.g., the embedding space of BERT clusterings), or the combination of these spaces. Thus, the generated adversarial texts are more semantically close to the original inputs. Extensive experiments reveal that state-of-the-art (SOTA) large-scale LMs (e.g., DeBERTa-v2) and defense strategies (e.g., FreeLB) are still vulnerable to SemAttack. We further demonstrate that SemAttack is general and able to generate natural adversarial texts for different languages (e.g., English and Chinese) with high attack success rates. Human evaluations also confirm that our generated adversarial texts are natural and barely affect human performance. Our code is publicly available at https://github.com/AI-secure/SemAttack., Comment: Published at Findings of NAACL 2022

Microplastics (MPs) pollution has drawn increasing concern due to its widespread occurrence and potential risks in the environment. The reliable methods and instruments for fast analysis of microplastics (MPs) less than 5 mm are urgently needed. In this study, a new method based on custom-made portable pyrolysis-mass spectrometry (Pyr-MS) is developed, which enables rapid identification and mass related quantification of MPs. MPs are decomposed in the compact pyrolyzer and then directly analyzed in the portable MS by the chemical fingerprints of polymers including characteristic ions and their special ratio. It avoids the complex extraction and separation procedures of the pyrolysis/thermogravimetric-gas chromatography-mass spectrometry (Pyr/TGA-GC-MS), realizes the rapid analysis of MPs in 5 min, and thus can practically apply to a large number of MPs samples. In comparison to Fourier transform infrared spectroscopy (FT-IR) and Raman, this method is not limited by the shape, size, and color of MPs. Four common plastics including polyethylene (PE), polypropylene (PP), polystyrene (PS), and poly(methyl methacrylate) (PMMA) were investigated to verify the feasibility of this method. The environmental MPs samples collected from a beach were successfully identified and quantified, demonstrating the simplicity and practicality of this approach. The influence of plastics aging on the chemical fingerprints and the potential of mixed plastics detection by Pyr-MS are also assessed. The portable Pyr-MS could provide a promising tool for in-field analysis of MPs such as ship-based marine MPs surveys.

The data generated by the launch vehicle test launch system has the characteristics of big data and small samples. Using small sample learning to start from a small amount of faulty data, and learning and processing sample data through data enhancement and metric learning strategies can greatly improve the effect of data mining. In view of the current situation that the deep learning method in the launch vehicle test system has not been used on a large scale, the characteristics of the data generated by the launch vehicle test launch are analyzed, and the method of small sample learning based on the deep neural network is combined with the data analysis of the launch vehicle test. And expounded the potential value and significance of this method to the development of launch vehicle test system.

Beta adrenergic receptors (βARs) mediate physiologic responses to the catecholamines epinephrine and norepinephrine released by the sympathetic nervous system. While the hormone epinephrine binds β1AR and β2AR with similar affinity, the smaller neurotransmitter norepinephrine is approximately tenfold selective for the β1AR. To understand the structural basis for this physiologically important selectivity, we solved the crystal structures of the human β1AR bound to an antagonist carazolol and different agonists including norepinephrine, epinephrine and BI-167107. Structural comparison revealed that the catecholamine-binding pockets are identical between β1AR and β2AR, but the extracellular vestibules have different shapes and electrostatic properties. Metadynamics simulations and mutagenesis studies revealed that these differences influence the path norepinephrine takes to the orthosteric pocket and contribute to the different association rates and thus different affinities.

This study investigated the effect of activated silica on both the polymerization mechanism and strength development of municipal solid waste incineration (MSWI) bottom ash alkali-activated mortars, with a specific focus on increasing the silica content by adding either solid or liquid sodium silicate. The results show that such additives increase the content of active silicon and improve the resulting compressive strength of mortars, which is more effectively enhanced by liquid solid sodium silicate addition. However, a significant decline of these effects was found with increased addition of sodium silicate. Solid sodium silicate is difficult to dissolve; therefore, increasing its content not only fails to improve the content of active silicon but also causes precipitation. Using liquid sodium silicate could further improve the content of active silicon; however, excessive addition will result in a large surplus of activated silicon and thus, causing sodium and magadiite precipitation.

High-quality low Sn-content GeSn film has been grown on tensile strained Ge/Si (100) substrate using a physical vapor deposition reactor and no subsequent annealing was carried out after the deposition of the film. High Resolution X-ray diffraction (HR-XRD) measurement was performed to estimate the crystallinity and the residual strain in the Ge layer. Secondary-ion mass spectrometry (SIMS) and X-ray photoelectron spectrometer (XPS) show Sn incorporation of the film is approximately 3%. High-resolution transmission electron microscopy (TEM) and atomic force microscopy (AFM) results show that the crystallinity of the film is quite good and it shows a smooth surface (RMS = 0.744 nm) in 5 µm × 5 µm scan. Raman spectroscopy and photoluminescence (PL) measurements were carried out to study the structural and optical properties of the film. Room-temperature PL of the film was observed and it results in a decrease in the difference between Γ and L valleys of tensile strained Ge (0.21%) from 87 meV to 76 meV, which makes this method promising for obtaining Pseudo-direct bandgap group IV films.

Power factor correction (PFC) converter is widely utilized in grid-connected equipment and power adapter, etc. Conventional PFC Buck converter is not proper to maintain good performance at low output voltage with a wide input range. In the bridge-based PFC converter, the forward voltage of rectifier diodes is an important source of power loss. For overcoming the above-mentioned issues, a bridgeless PFC converter based on switched-capacitor dual-resonance tank is proposed in this paper. The switched-capacitor dual-resonance tank is meaningful to improve voltage regulating capacity and the bridgeless structure is helpful to eliminate rectifier diode loss. Additionally, only small inductors are utilized in the proposed PFC converter, which is useful to improve power density.

Aiming at the problems existing in the current fault location methods of distribution grid, such as precise calculation of wave velocity and the finite precision of fault location, a precise fault location method of traveling wave in the distribution grid based on multiple measuring points is proposed. In this method, the line-mode traveling wave of a specific frequency is selected as the basis for the time calibration of the initial wave head, and the circuit is divided into fault zone and non-fault zone. The traveling wave velocity is real time calculated by using the traveling wave of the non-fault zone. The fault branch identification matrix (FBIM) is constructed and compared with the fault branch identification array line by line to identify the fault branch (FB). On this basis, the fault distance is solved precisely by using redundant end-point traveling wave and least square method. This method only requires the placement of measuring points at the end of each branch, which to some extent solves the problem of limitation of measuring point allocation. Simulation results show that the method is highly reliable and has high fault location accuracy in different fault locations.

In this work, electromagnetic heating was firstly explored as sample introduction approach in portable microplasma-atomic emission spectrometer to achieve the direct, rapid analysis of soil sample. The device primarily consists of an electromagnetic heating unit, a dielectric barrier discharge (DBD) excitation source and an optical signal acquisition unit. A W-boat was used as an electromagnetic heating medium and sample carrier, and copper coil spiraled around the tube was used as magnetic induction coil. With applying a voltage on copper coil, W-boat was electromagnetically heated to vaporize analyte-containing species for sample introduction into the microplasma. The portable battery-powered device is controlled by a miniature touch screen computer with the main advantages of small size (40.5 cm (l) × 30 cm (w) × 15 cm (h).), light weight (less than 7 kg), low-power consumption (the average power consumption is 118 W). By this method, Hg, Cd and Pb in soil were simultaneously analyzed within 4 min. Under the optimal conditions, the limits of detection for Hg, Cd and Pb in soils were 8.0 μg/kg, 17.8 μg/kg and 3.5 mg/kg, respectively, meeting the requirements for environmental quality standards for soils of China. Different types of CRM soils were analyzed, demonstrating good accuracy, stability and utility of this method. This technique could be a promising and powerful tool for on-site, rapid analysis of heavy metals in soil even other solid samples. Electromagnetic heating mode provides a good alternative for solid sampling to develop portable, miniaturized atomic spectrometers for solid sample analysis.

Surface charge accumulation on spacer is an important factor to cause surface flashover. An experimental set-up is established to measure surface potential over a truncated cone-type spacer under DC voltage in SF 6 gas at atmospheric pressure using a Kelvin vibrating electrostatic probe. The surface charge density is calibrated based on multipoint measurement technique, which takes the influence of electrostatic probe into account. The experimental results show that surface charge distribution patterns can be divided into three classes including centrosymmetric distribution, spot-like distribution, and cloud-like distribution. The symmetrically distributed charges are injected by electrode, which migrate along spacer surface through the surface conductivity. While the charges showing spot-like and cloud-like distribution are generated by the ionisation of SF 6 due to local electrical field concentrated. Besides, the hetero-charges are more easily to be saturated with different charging durations and the polarity of the net charge is the same as that of applied voltage.

In this paper, a novel fully-depleted Ge1-xSnx n-Tunneling FET (FD Ge1-xSnx nTFET) with field plate is investigated theoretically based on the experiment previously published. The energy band structures of Ge1-xSnx are calculated by EMP and the band-to-band tunneling (BTBT) parameters of Ge1-xSnx are calculated by Kane's model. The electrical characteristics of FD Ge1-xSnx nTFET and FD Ge1-xSnx nTFET with field plate (FD-FP Ge1-xSnx nTFET) having various Sn compositions are investigated and simulated with quantum confinement model. The results indicated that the GIDL effect is serious in FD Ge1-xSnx nTFET. By employing the field plate structure, the GIDL effect of FD-FP Ge1-xSnx nTFET is suppressed and the off-state current Ioff is decreased more than 2 orders of magnitude having Sn compositions from 0 to 0.06 compared with FD Ge1-xSnx nTFET. The impact of the difference of work function between field plate metal and channel Φfps is also studied. With the optimized Φfps = 0.0 eV, the on-state current Ion = 4.6 × 10−5 A/μm, the off-state current Ioff = 1.6 × 10−13 A/μm and the maximum on/off ration Ion/Ioff = 2.9 × 108 are achieved.

Ocean current energy harvester is a promising infrastructure to achieve self-powered marine wireless sensing system. This study proposes and investigates an underwater flag-like Triboelectric Nanogenerator (UF-TENG) based on the flow-induced vibration. The UF-TENG consists of two conductive ink-coated polyethylene terephthalate membranes and one strip of poly tetra fluoroethylene membrane with their edges sealed up by a waterproof PTFE tape. In this way, the triboelectric layers are prevented from contacting water. It is verified that the vortex street induced by a cylinder enhances the vibration of the UF-TENG. The low velocity startup enables the UF-TENG to harvest extremely low-velocity ocean current energy, e.g., presently achieving 0.133 m/s as the critical startup velocity. The proposed UF-TENG has a simpler structure and better low velocity performance when comparing with electromagnetic generators and piezoelectric generators. Parametric studies are conducted to evaluate the influence of geometrical parameters of the UF-TENG on the vibration behavior and output performance. It is demonstrated that the underwater electrical appliance can be powered by parallel UF-TENG units. The present UF-TENG is a more cost-effective and more accessible hydroelectric technology to utilize the renewable ocean current for powering sensors or micro electric appliances in Internet of Things.

In this paper, a novel structure of the fully-depleted Ge-on-Insulator (GOI) n-channel MOSFET with field plate is proposed and studied by two-dimensional numerical simulation. The results indicate that the gated-induced drain leakage (GIDL) of the fully-depleted GOI NMOSFET with field plate (FD-FP NMOSFET) is suppressed effectively. Besides, off-state current Ioff decreases by 2 orders of magnitude compared with the device without field plate. The impacts of the distance of field plate from the drain Lcb and the difference of work function between field plate metal and channel material Φfps on the electrical characteristics of FD-FP NMOSFET are investigated. FD-FP NMOSFET with a Φfps of 0 eV and a Lcb of 5 nm, demonstrates a reduction in Ioff by more than 3 orders of magnitude as compared with the control device. An on/off ratio Ion/Ioff = 2.57 × 107, and a sub-threshold swing of 76.8mV/decade are achieved.

This paper proposes a parameter calculation method for the mixed initiation circuit with both nonel detonators (NDs) and electronic detonators (EDs) to increase the detonator delay for reducing the blast-induced vibration in tunnel blasting and to ensure safe circuit operation. The circuit involves the outside-hole delay for increasing the delay numbers under the premise of safe circuit operation. The time calculation and vibration-reduction effects of the circuit were quantitatively determined through mathematical modeling and field experimental studies. A calculation model of mixed detonator groups was established based on three constraint conditions: no delay irregularly, no misfire, and an increased delay number. The main parameters obtained were the initiation sequence of the EDs, the delay number of the NDs and the time interval of the EDs inside the blastholes. The factor considered in the mathematical modeling was the delay error of the NDs. The calculation results agreed well with experimental results, the latter confirming that the mixed initiation circuit was feasible and safe when using a 90 ms delay outside the blasthole. In addition, the delay numbers of the mixed-detonator group were increased by 40% relative to those of NDs. Compared with conventional blasting that reduces the advance per round, blasting with the mixed initiation circuit using an outside-hole delay produced 82.3% less blast-induced vibration. It was also found that the blasting cost could be reduced by 54.3% compared with that of using EDs only. Overall, the mixed initiation method had a positive effect on tunnel controlled-blasting. The research methods and results are expected to be useful in guiding related engineering efforts.

In this paper, a novel junctionless Ge n-Tunneling Field-Effect Transistors (TFET) structure is proposed. The simulation results show that Ion = 5.5 × 10−5A/μm is achieved. The junctionless device structure enhances Ion effectively and increases the region where significant BTBT occurs, comparing with the normal Ge-nTEFT. The impact of the lightly doped drain (LDD) region is investigated. A comparison of Ion and Ioff of the junctionless Ge n-TFET with different channel doping concentration ND and LDD doping concentration NLDD is studied. Ioff is reduced 1 order of magnitude with the optimized ND and NLDD are 1 × 1018cm−3 and 1 × 1017 cm−3, respectively. To reduce the gate induced drain leakage (GIDL) current, the impact of the sloped gate oxide structure is also studied. By employing the sloped gate oxide structure, the below 60 mV/decade subthreshold swing S = 46.2 mV/decade is achieved at Ion = 4.05 × 10−5A/μm and Ion/Ioff = 5.7 × 106.

In this paper, the structure of fully-depleted Ge NMOS with P-substrate (FDP-NMOS) is proposed. The DIBL effect of fully depleted GeOI NMOS (FD-NMOS) and FDP-NMOS has been studied based on the simulation results. It is demonstrated that DIBL of FD-NMOS occurs at the deep bulk of channel before the surface. From the current-voltage (I D -V G ) characteristics, the DIBL effect, the leakage current and the on-state current are determined. The results indicate that with the doping concentration of P-substrate (N B ) increasing, the DIBL effect is lower and the leakage current decreases significantly. Therefore, the FDP-NMOS has excellent subthreshold characteristics. When N B is 10 × 10 17 /cm 3 , the subthreshold swing is 76.8 mV/dec and the on/off ratio is 1.65 × 10 8 , respectively. The on/off ratio of FDP-NMOS increases more than 4 orders compared with the FD-NMOS and the experimental results.

Background Wound infections, especially multidrug-resistant (MDR) bacterial infections, are a major challenge in clinical medicine. Methods In this study, a new type of antibacterial sponge was prepared from a solution containing a chitosan-polyvinyl alcohol (CTS-PVA) emulsion with added polyhexamethylene guanidine hydrochloride (PHMG) in a homogeneous medium using lyophilization technology. The antibacterial ability of and CTS-PVA/PHMG sponge against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, Methicillin-resistant Staphylococcus aureus, multidrug-resistant Pseudomonas aeruginosa, and multidrug-resistant Acinetobacter baumannii in vitro. The structure and physical properties were characterized. The sponge dressing was tested in a Pseudomonas aeruginosa-infected full-thickness mouse skin wound defect model. The effects were evaluated by wound area measurement and histological analysis. Results The CTS-PVA/PHMG sponge showed broad-spectrum antibacterial ability, including for MDR bacterial stains from clinical sources, while maintaining excellent physicochemical properties, including a high swelling degree and good moisture retention capability. Scanning electron microscopy images displayed the surface morphology of the CTS-PVA/PHMG sponge dressing. The detection of the wound healing rate and histological analysis supported that the new dressing can alleviate the inflammation and accelerate the healing speed of infected wounds and in vivo. Conclusions CTS-PVA/PHMG sponge shows broad-spectrum antibacterial activity, which can provide a new pathway for clinical prevention and treatment of superbug-infected wounds.

In order to achieve high efficiency absorption of CO2 by fresh cement paste, a special CO2 absorption device was designed. Then the influences of stirring rate (SR), water-to-cement ratio(W/C), superplasticizer type and its addition order on the CO2 absorption rate (CO2 AR) and CO2 ultimate absorption amount(CO2 UAA)were investigated. Moreover, the fluidity and mechanical properties of cement paste with different CO2 absorption amount were determined. According to the experimental results, with increasing absorption amount of CO2, the cement paste gradually loses fluidity and becomes hardened, indicating CO2 absorption of cement paste has reached to CO2 UAA. Meanwhile, increasing SR can effectively increase CO2 AR, while the CO2 UAA cannot be increased. Increasing W/C results in an increase in both CO2 AR and CO2 UAA. On the other hand, superplasticizer added before CO2 absorption neither can help to increase CO2 UAA nor improve fluidity of the carbonated cement paste. Superplasticizer added after CO2 absorption can improve fluidity of the carbonated cement paste but is barely helpful for increasing the CO2 UAA. The influence of CO2 absorption on early mechanical strength of the carbonated cement mortar is not obvious while the later mechanical strength of the carbonated cement paste can be improved. SEM and EDS analysis indicate that with an increase in CO2 absorption amount (CO2 AA), water in the cement paste is gradually consumed, forming columnar crystals of ettringite and calcium carbonate and increasing the cement particles and the flocculation structure per unit volume of cement paste. As a result, cement paste gradually loses its fluidity.

Wide voltage range converters are significant for photovoltaic power generation system, battery charging, etc. Resonant converter has been preferred topology for these applications, however, some demerits exist: 1) Difficult to realize wide voltage gain range and low circulating current losses; 2) Widely regulated switching frequency to adapt to wide voltage gain range; 3) Poor regulation at light load. Based on above-mentioned shortcomings, dual-resonance-core based step-up/down switched capacitor converter topology is presented in this paper. Utilizing hybrid control strategy, non-overlapping control strategy is used in the Buck-type mode and overlapping control strategy is applied in the Boost-type mode with common switching frequency range, and therefore, reduced frequency range in the presented converter is achieved. Moreover, wide voltage gain range can be obtained due to step-up/down capacity in the proposed converter. Furthermore, conversion ratio of proposed converter can be reduced to zero theoretically by using dual-resonance-core existed in the resonant switched capacitor converter. Finally, comprehensive operational principle analysis and performance analysis are provided, and a 48V to 2890V/100W prototype is built to verify the analysis.

Microplastics (MPs) pollution in the marine has become a global concern. To obtain accurate measurements of MPs in the marine sediments is important for understanding its effects and potential risks to the environment. In this study, we developed a novel method for extracting MPs from sediments by density flotation of sodium dihydrogen phosphate (NaH2PO4) solution, which utilized the heating-assisted to increase the density of separation solution. It features high density, nontoxic, and economic, indicating its promising application in the MPs extraction. A standard procedure based on NaH2PO4 for extracting MPs from sediments was established and validated by the recovery experiments of seven common plastics. Results showed NaH2PO4 solution exhibited higher recovery rates than the commonly-used NaCl solution; three plastics with high density couldn't be recovered by NaCl, while NaH2PO4 was available for all the studied MPs. A large number of real beach samples was collected and validated by this method, and the abundance and characteristic of the collected MPs were further analyzed. Results exhibited the heating-assisted NaH2PO4 could be a promising way for extracting MPs in environmental samples.

The uncertain mechanical parameters of artificial frozen soil in deep alluvium are the key factors for computing the stochastic stress fields and stochastic deformation fields of artificial freezing engineering. In this study, a series of mechanical parameters tests for the artificially frozen clay are carried out, and the statistical data of elastic modulus, strength and Poisson ratio of frozen clay under three different low temperature conditions (−20 °C, −15 °C and −10 °C) are obtained. The experimental semi-variogram values of the mechanical parameters for artificially frozen clay under different temperature conditions are calculated and analyzed. The results show that the test data meets the requirements of the coefficient of variation analysis and the elastic modulus, strength and poisson ratio basically meet the normal distribution. The variability of the mechanical parameters for artificially frozen clay is basically in the degree of moderate to weak variability. The optimal theoretical variation function model of basic mechanical parameters of frozen clay is Gaussian model. The correlation of soil parameters calculated by Gauss model at smaller distances is greater than that of Exponential model and Spherical model. The mechanical parameters of artificially frozen clay are strongly dependent in spatial range. This study can improve our understanding of the variation characteristics of uncertain mechanical parameters for artificial frozen soil in deep alluvium and provide a theoretical basis and reference for the stochastic mechanical analysis of artificial freezing engineering.

Objective To explore the significance of prostatic calculi in prostate surgery. Methods During the beginning of 2010 to the end of 2017, a retrospective analysis was made of 821 cases of benign prostatic hyperplasia (BPH) with prostatic calculi admitted to our hospital. During 2010 to 2015, transurethral resection of the prostate (TURP) was performed. And then, from 2015 to 2017, it was replaced as transurethral laser vaporization of the prostate (TULVP). There were 5 converted to open. We should remove the prostate tissue til the surgical capsule by electrocision or vaporization. If annular fibrous tissue or prostatic calculi are encountered during the operation, the calculi will be exfoliated, and then stop operation. Results All the operations were successfully completed, with an average times of 47 minutes (22-117 minutes), bleeding of 50ml (15-350 ml), indwelling catheter for 5.7 days (3-10 days), and continuous bladder irrigation for 1.3 days (1-5 days). During the follow-up period of 0.4-5 years, the urination symptoms and quality of life of the post-operation patients were significantly improved. Conclusions Prostate calculi can be used as a marker of the depth of operation for BPH.

The accumulated charge on insulator surface is an important factor to trigger surface flashover. A surface charge experimental setup as well as measurement system under high gas pressure is built. An active electrostatic probe (Trek 3455ET, Model 341B) is used to measure surface potential distribution on a downsized cone-type spacer in SF 6 /N 2 mixtures of different pressure under DC voltage. The actual charge density distribution is computed by the charge inverse algorithm, which considers the impact of the probe. The surface charge distribution shows similar shape at different pressure, including the homo-charges presenting a symmetrical distribution and a streak-like distribution. For the home-charges presenting a symmetrical distribution, they come from surface conductivity. For the streak-like distribution, they are located between central and grounded electrode. These charges come from the ionization of SF 6 due to the local electrical field concentrated.

The charges accumulated on spacer surface is an important factor to cause surface flashover. To investigate surface charge distribution characteristics of GIL spacer, a downsized truncated cone-type spacer is designed and manufactured. An experimental and measurement system is established to scan surface potential of this spacer under DC voltages in SF 6 by electrostatic probe method. A calibration method with high resolution is built to compute the actual surface charge distribution. There are two classes of charge distribution observed on spacer surface, including centrosymmetric distribution (the first class), streak-like distribution and spot-like distribution (the second class). It is analyzed that surface conductivity, SF 6 gas conductivity and volume conductivity contribute to different classes of charge distribution respectively.

For motion track errors in the measurement of underwater noise sources, utilized MUSIC near-field focused beamforming correcting the sound source trajectory, established measurement model based on the algorithm of near-field focused beamforming. MUSIC algorithm is based on the characteristics decomposition of the covariance matrix to obtain the noise subspace and the signal subspace corresponding to signal components, and achieve DOA estimation using the two-orthogonal subspace. Through numerical simulations obtaining the following conclusions: After utilizing the modified data reconstructing the sound field, the amplitude reconstructive accuracy and phase reconstructive accuracy have all exist different improvements, which proved the correctness and effectiveness of the algorithm.

The dynamic threshold algorithm (DTA) presented by Pan Tompkins is a popular QRS detection method, and it has high sensitivity and specificity. However, the accuracy of this algorithm would be compromised if its sensitivity is increased. In this study, an enhanced dynamic threshold algorithm (EDTA) based on dynamic threshold rules is proposed, which add a compensation scheme to reduce the rate of misdetection and missed detection of R wave in low signal-to-noise ratio condition, sensitivity and detection error rate are calculated on simulated and clinical data to compare the performance between EDTA and DTA, and EDTA yields a competitive results. For the clinical data, the average accuracy rate of EDTA is 99.24%, which is higher than that of DTA at 95.98%. Further compared experiments among EDTA and the two other popular algorithms are conducted and the results of their validation over a public database are given and discussed, which prove our superiority.

This paper discusses the so-called “crisis” and “death” of comparative literature as a discipline, arguing that the congenital deficiency and internal illogicality are the root causes that make comparative literature lose the disciplinary consciousness in its growth. The theoretical turn, great emergence of cultural studies and the flooding of deconstructive torrent within the past thirty years are the external causes that lead the discipline into “crisis” and “death.” The paper asserts that despite its crises, comparative literature is not dying, but growing rapidly. The paper suggests that only by effectively constructing its disciplinary theory can Chinese comparative literature possibly strive to be the representative of the discipline in its third stage after French and American schools.

p53, as a tumor suppressor, plays a critical role in inhibiting development of cancer. Generally, p53 sustains a constant low level in cells at physiological conditions, however, p53 is significantly increased in response to various stresses, through which regulates cell cycle arrest, senescence, DNA damage repair and apoptosis. Functional modifications of p53 involve a series of posttranslational modifications including ubiquitination, acetylation, phosphorylation, sumolation/ neddylation and methylation. These modifications interact each other and thus mutually regulate p53 activities. This review focuses on interactions of various posttranslational modifications of p53, and tries to provide a potential strategy for clinical cancer therapeutics.

With millions of apps that can be downloaded from official or third-party market, Android has become one of the most popular mobile platforms today. These apps help people in all kinds of ways and thus have access to lots of user's data that in general fall into three categories: sensitive data, data to be shared with other apps, and non-sensitive data not to be shared with others. For the first and second type of data, Android has provided very good storage models: an app's private sensitive data are saved to its private folder that can only be access by the app itself, and the data to be shared are saved to public storage (either the external SD card or the emulated SD card area on internal FLASH memory). But for the last type, i.e., an app's non-sensitive and non-shared data, there is a big problem in Android's current storage model which essentially encourages an app to save its non-sensitive data to shared public storage that can be accessed by other apps. At first glance, it seems no problem to do so, as those data are non-sensitive after all, but it implicitly assumes that app developers could correctly identify all sensitive data and prevent all possible information leakage from private-but-non-sensitive data. In this paper, we will demonstrate that this is an invalid assumption with a thorough survey on information leaks of those apps that had followed Android's recommended storage model for non-sensitive data. Our studies showed that highly sensitive information from billions of users can be easily hacked by exploiting the mentioned problematic storage model. Although our empirical studies are based on a limited set of apps, the identified problems are never isolated or accidental bugs of those apps being investigated. On the contrary, the problem is rooted from the vulnerable storage model recommended by Android. To mitigate the threat, we also propose a defense framework.

The popularity of mobile device has made people's lives more convenient, but threatened people's privacy at the same time. As end users are becoming more and more concerned on the protection of their private information, it is even harder to track a specific user using conventional technologies. For example, cookies might be cleared by users regularly. Apple has stopped apps accessing UDIDs, and Android phones use some special permission to protect IMEI code. To address this challenge, some recent studies have worked on tracing smart phones using the hardware features resulted from the imperfect manufacturing process. These works have demonstrated that different devices can be differentiated to each other. However, it still has a long way to go in order to replace cookie and be deployed in real world scenarios, especially in terms of properties like uniqueness, robustness, etc. In this paper, we presented a novel method to generate stable and unique device ID stealthy for smartphones by exploiting the frequency response of the speaker. With carefully selected audio frequencies and special sound wave patterns, we can reduce the impacts of non-linear effects and noises, and keep our feature extraction process un-noticeable to users. The extracted feature is not only very stable for a given smart phone speaker, but also unique to that phone. The feature contains rich information that is equivalent to around 40 bits of entropy, which is enough to identify billions of different smart phones of the same model. We have built a prototype to evaluate our method, and the results show that the generated device ID can be used as a replacement of cookie., Comment: 12 pages

In this work, the carrier microscopic transport process of biaxial strained Si p-channel metal-oxide-semiconductor field-effect transistor (PMOSFET) under γ -ray radiation has been studied. Effect of γ-ray on devices and the relationship between the variation of device electrical characteristics and the total dose are investigated. A model for considering the degradation of threshold voltage and transconductance due to the total dose radiation is established. Based on this model, numerical simulation has been carried out. Results show that the threshold voltage of PMOSFET decreases with increasing radiation dose. At a lower total dose, the threshold voltage decreases linearly. However, at a higher total dose, it becomes saturated. The degradation can be explained by the generation of trapped charges which increase the impact possibility of carriers in the channel and induce the reduction of mobility and transconductance accordingly. Finally, the simulation results are compared with the experimental data. A good agreement is observed, indicating the validation of our proposed model.