A Novel DDoS Attack Detection Method Using Optimized Generalized Multiple Kernel Learning

Distributed Denial of Service(DDoS)attack has become one of the most destructive network attacks which can pose a mortal threat to Internet security.Existing detection methods cannot effectively detect early attacks.In this paper,we propose a detection method of DDoS attacks based on generalized multiple kernel learning(GMKL)combining with the constructed parameter R.The super-fusion feature value(SFV)and comprehensive degree of feature(CDF)are defined to describe the characteristic of attack flow and normal flow.A method for calculating R based on SFV and CDF is proposed to select the combination of kernel function and regularization paradigm.A DDoS attack detection classifier is generated by using the trained GMKL model with R parameter.The experimental results show that kernel function and regularization parameter selection method based on R parameter reduce the randomness of parameter selection and the error of model detection,and the proposed method can effectively detect DDoS attacks in complex environments with higher detection rate and lower error rate.

International consensus guidelines on robotic pancreatic surgery in 2023

Background:With the rapid development of robotic surgery,especially for the abdominal surgery,robotic pancreatic surgery(RPS)has been applied increasingly around the world.However,evidence-based guidelines regarding its application,safety,and efficacy are still lacking.To harvest robust evidence and comprehensive clinical practice,this study aims to develop international guidelines on the use of RPS.Methods:World Health Organization(WHO)Handbook for Guideline Development,GRADE Grid method,Delphi vote,and the AGREE-II instrument were used to establish the Guideline Steering Group,Guideline Development Group,and Guideline Secretary Group,formulate 19 clinical questions,develop the recommendations,and draft the guidelines.Three online meetings were held on 04/12/2020,30/11/2021,and 25/01/2022 to vote on the recommendations and get advice and suggestions from all involved experts.All the experts focusing on minimally invasive surgery from America,Europe and Oceania made great contributions to this consensus guideline.Results:After a systematic literature review 176 studies were included,19 questions were addressed and 14 recommendations were developed through the expert assessment and comprehensive judgment of the quality and credibility of the evidence.Conclusions:The international RPS guidelines can guide current practice for surgeons,patients,medical societies,hospital administrators,and related social communities.Further randomized trials are required to determine the added value of RPS as compared to open and laparoscopic surgery.

A review of the influencing factors on teleseismic traveltime tomography

Teleseismic traveltime tomography is an important tool for investigating the crust and mantle structure of the Earth.The imaging quality of teleseismic traveltime tomography is affected by many factors,such as mantle heterogeneities,source uncertainties and random noise.Many previous studies have investigated these factors separately.An integral study of these factors is absent.To provide some guidelines for teleseismic traveltime tomography,we discussed four main influencing factors:the method for measuring relative traveltime differences,the presence of mantle heterogeneities outside the imaging domain,station spacing and uncertainties in teleseismic event hypocenters.Four conclusions can be drawn based on our analysis.(1)Comparing two methods,i.e.,measuring the traveltime difference between two adjacent stations(M1)and subtracting the average traveltime of all stations from the traveltime of one station(M2),reveals that both M1 and M2 can well image the main structures;while M1 is able to achieve a slightly higher resolution than M2;M2 has the advantage of imaging long wavelength structures.In practical teleseismic traveltime tomography,better tomography results can be achieved by a two-step inversion method.(2)Global mantle heterogeneities can cause large traveltime residuals(up to about 0.55 s),which leads to evident imaging artifacts.(3)The tomographic accuracy and resolution of M1 decrease with increasing station spacing when measuring the relative traveltime difference between two adjacent stations.(4)The traveltime anomalies caused by the source uncertainties are generally less than 0.2 s,and the impact of source uncertainties is negligible.

Combinatorial optimization of perovskite-based ferroelectric ceramics for energy storage applications

With the increasing impacts of climate change and resource depletion,dielectric capacitors,with their exceptional stability,fast charging and discharging rates,and ability to operate under more extreme conditions,are emerging as promising high-demand candidates for high-performance energy storage devices,distinguishing them from traditional electrochemical capacitors and batteries.However,due to the shortcomings of various dielectric ceramics(e.g.,paraelectrics(PEs),ferroelectrics(FEs),and antiferroelectrics(AFEs)),their low polarizability,low breakdown strength(BDS),and large hysteresis loss limit their standalone use in the advancement of energy storage ceramics.Therefore,synthesizing novel perovskite-based materials that exhibit high energy density,high energy efficiency,and low loss is crucial for achieving superior energy storage performance.In this review,we outline the recent development of perovskitebased ferroelectric energy storage ceramics from the perspective of combinatorial optimization for tailoring ferroelectric hysteresis loops and comprehensively discuss the properties arising from the different combinations of components.We also provide future guidelines in this realm.Therefore,the combinatorial optimization strategy in this review will open up a practical route toward the application of new high-performance ferroelectric energy storage devices.

Water-involving transfer hydrogenation and dehydrogenation of N-heterocycles over a bifunctional MoNi_(4)electrode

A room-temperature electrochemical strategy for hydrogenation(deuteration)and reverse dehydrogenation of N-heterocycles over a bifunctional MoNi_(4)electrode is developed,which includes the hydrogenation of quinoxaline using H2O as the hydrogen source with 80%Faradaic efficiency and the reverse dehydrogenation of hydrogen-rich 1,2,3,4-tetrahydroquinoxaline with up to 99%yield and selectivity.The in situ generated active hydrogen atom(H^(*))is plausibly involved in the hydrogenation of quinoxaline,where a consecutive hydrogen radical coupled electron transfer pathway is proposed.Notably,the MoNi_(4)alloy exhibits efficient quinoxaline hydrogenation at an overpotential of only 50 mV,owing to its superior water dissociation ability to provide H^(*)in alkaline media.In situ Raman tests indicate that the Ni^(Ⅱ)/Ni^(Ⅲ)redox couple can promote the dehydrogenation process,representing a promising anodic alternative to low-value oxygen evolution.Impressively,electrocatalytic deuteration is easily achieved with up to 99%deuteration ratios using D2O.This method is capable of producing a series of functionalized hydrogenated and deuterated quinoxalines.

DDoS Attack Detection via Multi-Scale Convolutional Neural Network

Distributed Denial-of-Service(DDoS)has caused great damage to the network in the big data environment.Existing methods are characterized by low computational efficiency,high false alarm rate and high false alarm rate.In this paper,we propose a DDoS attack detection method based on network flow grayscale matrix feature via multi-scale convolutional neural network(CNN).According to the different characteristics of the attack flow and the normal flow in the IP protocol,the seven-tuple is defined to describe the network flow characteristics and converted into a grayscale feature by binary.Based on the network flow grayscale matrix feature(GMF),the convolution kernel of different spatial scales is used to improve the accuracy of feature segmentation,global features and local features of the network flow are extracted.A DDoS attack classifier based on multi-scale convolution neural network is constructed.Experiments show that compared with correlation methods,this method can improve the robustness of the classifier,reduce the false alarm rate and the missing alarm rate.

聚3-己基噻吩:非富勒烯太阳能电池中的量子效率损失和电压损失

聚3-己基噻吩(P3HT)以其合成工艺简单、成本低廉的优势,成为有机光伏领域中最具吸引力的电子给体材料之一。然而,目前P3HT:非富勒烯太阳能电池的光伏性能仍然较差。在本工作中,我们证明了与P3HT:富勒烯太阳能电池相比,较快的电荷转移态的非辐射衰减速率(K_(nr))是导致P3HT:非富勒烯太阳能电池中较低的量子效率和较高的电压损失的原因。然后,我们研究了基于非富勒烯受体ZY-4Cl的太阳能电池的工作机理。研究结果表明与P3HT:非富勒烯体系相比,P3HT:ZY-4Cl中K_(nr)的降低改善了器件的量子效率,同时降低了电压损失。K_(nr)降低的原因可以部分归因于电荷转移态能量的增加。此外,给体分子和受体分子之间的距离(DA间距)的增大也是K_(nr)减少的重要原因。因此,我们得出结论:为了提高P3HT太阳能电池的性能,需进一步降低器件的K_(nr),这可通过增加活性层中的DA间距来实现。

A DDoS Attack Information Fusion Method Based on CNN for Multi-Element Data

Traditional distributed denial of service(DDoS)detection methods need a lot of computing resource,and many of them which are based on single element have high missing rate and false alarm rate.In order to solve the problems,this paper proposes a DDoS attack information fusion method based on CNN for multi-element data.Firstly,according to the distribution,concentration and high traffic abruptness of DDoS attacks,this paper defines six features which are respectively obtained from the elements of source IP address,destination IP address,source port,destination port,packet size and the number of IP packets.Then,we propose feature weight calculation algorithm based on principal component analysis to measure the importance of different features in different network environment.The algorithm of weighted multi-element feature fusion proposed in this paper is used to fuse different features,and obtain multi-element fusion feature(MEFF)value.Finally,the DDoS attack information fusion classification model is established by using convolutional neural network and support vector machine respectively based on the MEFF time series.Experimental results show that the information fusion method proposed can effectively fuse multi-element data,reduce the missing rate and total error rate,memory resource consumption,running time,and improve the detection rate.

Research Progress of High Yield Cultivation Mode of Rice

Optimized high-yielding cultivation is of great significance to ensure stable and high yield of rice in China. This paper reviewed several super high-yielding cultivation modes, analyzed the effects of different cultivation modes on rice agronomic traits and physiological characteristics, and discussed the advances in rice mechanized cultivation and mode. Finally, the future development prospects of rice cultivation were put forward.

硝酸体系电解精炼制备高纯铜

高纯铜具有优良的延展性、导热性、导电性及较为稳定的化学性质,在半导体材料、光电子等领域应用广泛。本研究采用硝酸体系作为电解质,以4N金属铜为原料,一步电解精炼制备纯度为5N的高纯铜,系统研究了H_(2)O_(2)添加量、电流密度、电解液pH、Cu^(2+)浓度等因素对电解过程的影响。结果表明,硝酸体系电解精炼制备高纯铜的最佳工艺条件为Cu^(2+)浓度为80 g/L、pH=1.0、H_(2)O_(2)加入量为0.10 mL/100 mL、电流密度为200 A/m^(2)。在该条件下进行电解精炼,阴极沉积的高纯铜表面光滑平整,电流效率达到97%以上。对最佳条件下获得的阴极产物进行ICP-MS检测,其中S,Ni,Se,As,Sb,Pb,Bi等常见杂质元素含量均符合5N高纯铜的国家标准。

Reversible N6-methyladenosine of RNA:The regulatory mechanisms on gene expression and implications in physiology and pathology

N6-methyladenosine(m6A)is the most abundant inner RNA modification in eukaryotes.Due to the development of RNA sequencing technology,the distribution pattern of m6A in the transcriptome has been uncovered.Dynamically,the reversible N6-methylation is mediated by two types of proteins,which are classified as“writers”and“erasers”.Under the association of specific co-factors,writers show spatiotemporal N6-methyltransferase activity.Mechanically,m6A can be recognized by“reader”proteins or can directly modify RNA conformation,and it widely affects gene expression by mediating RNA stability,translation,splicing and export.m6A is involved in a series of physiology processes.Dysregulation of m6A is gradually defined as the pathogenesis of some diseases,e.g.,cancer and cardiovascular disease.Therefore,a good understanding of m6A is essential for molecular biology and pathology research.In this article we systemically present an overview of the functions and mechanisms of identified m6A regulators.The discovered biological and pathological processes affected by m6A are also summarized.We hope that readers with related research interests benefit from our review.

Electrosynthesis of ^(15)N-labeled amino acids from ^(15)N-nitrite and ketonic acids

^(15)N isotope-labeled amino acids(^(15)N-amino acids)are crucial in the fields of biology,medicine,and chemistry.^(15)N-amino acids are conventionally synthesized through microbial fermentation and chemical reductive amination of ketonic acids methodologies,which usually require complicated procedures,high temperatures,or toxic cyanide usage,causing energy and environmental concerns.Here,we report a sustainable pathway to synthesize ^(15)N-amino acids from readily available ^(15)N-nitrite(^(15)NO_(2)-)and biomass-derived ketonic acids under ambient conditions driven by renewable electricity.A mechanistic study demonstrates a ^(15)N-nitrite→^(15)NH_(2)OH→^(15)N-pyruvate oxime→^(15)N-alanine reaction pathway for ^(15)N-alanine synthesis.Moreover,this electrochemical strategy can synthesize six ^(15)N-amino acids with 68%–95%yields.Furthermore,a ^(15)N-labeled drug of ^(15)N-tiopronin,the most commonly used hepatitis treatment drug,is fabricated using ^(15)N-glycine as the building block.Impressively,^(15)N sources can be recycled by the electrooxidation of ^(15)NH4^(+) to ^(15)NO_(2)-with a method economy.This work opens an avenue for the green synthesis of ^(15)N-labeled compounds or drugs.

Optimizing a high-sensitivity NanoLuc-based bioluminescence system for in vivo evaluation of antimicrobial treatment

Focal and systemic infections are serious threats to human health.Preclinical models enable the development of new drugs and therapeutic regimens.In vivo,animal bioluminescence(BL)imaging has been used with bacterial reporter strains to evaluate antimicrobial treatment effects.However,high-sensitivity bioluminescent systems are required because of the limited tissue penetration and low brightness of the BL signals of existing approaches.Here,we report that NanoLuc(Nluc)showed better performance than LuxCDABE in bacteria.However,the retention rate of plasmid constructs in bacteria was low.To construct stable Staphylococcus aureus reporter strains,a partner protein enolase(Eno)was identified by screening of S.aureus strain USA300 for fusion expression of Nluc-based luciferases,including Nluc,Teluc,and Antares2.Different substrates,such as hydrofurimazine(HFZ),furimazine(FUR),and diphenylterazine(DTZ),were used to optimize a stable reporter strain/substrate pair for BL imaging.S.aureus USA300/Eno-Antares2/HFZ produced the highest number of photons of orange-red light in vitro and enabled sensitive BL tracking of S.aureus in vivo,with sensitivities of approximately 10 CFU from mouse skin and 750 CFU from mouse kidneys.USA300/Eno-Antares2/HFZ was a powerful combination based on the longitudinal evaluation of the therapeutic efficacy of antibiotics.The optimized S.aureus Eno-Antares2/HFZ pair provides a technological advancement for the in vivo evaluation of antimicrobial treatment.

Velocity structure and radial anisotropy beneath the northeastern Tibetan Plateau revealed by eikonal equation-based teleseismic P-wave traveltime tomography

The northeastern Tibetan Plateau serves as the frontier for the northeastward expansion of the plateau.In this area,the Tibetan Plateau interacts with the surrounding blocks,such as the Alxa Block,the Ordos Block,the Kunlun-West Qinling belt and the Sichuan Basin.Because of this expansion and interaction,this area suffers from intense deformation.At present,the evolution and deformation mechanisms of the northeastern Tibetan Plateau remain controversial.To provide new insights into these mechanisms,in this study,we conduct tomography of the P-wave velocity and radial anisotropy structures beneath the northeastern Tibetan Plateau.We choose a total of 667 teleseismic earthquakes from August 2006 to October 2020.Waveforms of these earthquakes were recorded by 921 broadband seismic stations in the northeastern Tibetan Plateau and surrounding areas.We first perform cross-correlation on waveforms of each station pair and obtain 770,749 P-wave traveltime differences.Then,we invert the differential traveltime data by applying eikonal equation-based teleseismic tomography.Finally,the P-wave velocity and radial anisotropy structures at depths from 30 to 800 km below the northeastern Tibetan Plateau are obtained.Our tomographic model shows clear low-velocity anomalies and positive radial anisotropy in the lower crust under the northeastern Qilian orogen,the northeastern Songpan-Ganzi belt and the western Qinling fold zone.These features are integrated to demonstrate the existence of lower crustal flow in the study area.Prominent low-velocity anomalies and positive radial anisotropy are found in the uppermost mantle beneath the Qilian orogen,the northeastern Songpan-Ganzi belt and western Qinling fold zone.These characteristics are combined to infer a weak lithosphere and horizontal asthenospheric flow under these tectonic units.Both the Ordos Block and the Sichuan Basin exhibit clear high-velocity anomalies and negative radial anisotropy in the uppermost mantle,thereby reflecting the high mechanical strength of the lithosphere beneath these blocks.High-velocity anomalies are also present in the upper mantle under the northern Chuandian block,potentially implying the northward subduction of the Indian plate.Furthermore,the front of the subducted Indian plate is imaged close to the Xianshuihe fault rather than the Kunlun fault.

Dual-site fluorescent probe for highly selective and sensitive detection of sulfite and biothiols

A dual-site fluorescent probe with double bond and aldehyde as reactive sites, was designed for the selective detection of sulfite and biothiols. Sulfite reacts with conjugate bond selectively, while Cys responses with aldehyde and GSH occurs substitution reaction. Different interactions cause different absorption and fluorescence responses. Moreover, it could be further applied in imaging in living cells.

Using water as the hydrogen source for electrocatalytic transfer hydrogen storage

Hydrogen gas(H2)is a promising energy carrier and an important chemical feedstock for industrial processes[1].A facile and atom-economic hydrogen storage strategy is markedly significant for hydrogen utilization.

Improving current and mitigating energy loss in ternary organic photovoltaics enabled by two well-compatible small molecule acceptors

Ternary organic photovoltaic(OPV)strategy is an effective but facile approach to enhance the photovoltaic performance for single-junction devices.Herein,a series of ternary OPVs were fabricated by employing a wide bandgap donor(PBDB-TF)and two acceptor-donor-acceptor(A-D-A)-type nonfullerene small molecule acceptors(NF-SMAs,called F-2 Cl and 3 TT-OCIC).As the third component,the near-infrared SMA,3 TT-OCIC,has complementary absorption spectrum,narrow bandgap and wellcompatible crystallization property to the host acceptor(F-2 Cl)for efficient ternary OPVs.With these,the optimal ternary devices yield significantly enhanced power conversion efficiency of 15.23%,one of the very few examples with PCE higher than15%other than Y6 systems.This is mainly attributed to the increased short-circuit current density of 24.92 m A cm^(-2) and dramatically decreased energy loss of 0.53 e V.This work presents a successful example for simultaneously improving current,minimizing energy loss and together with modifying the morphology of active layers in OPVs,which will contribute to the further construction of high performance ternary OPVs.