An immunization scheme for ransomware

In recent years, as the popularity of anonymous currencies such as Bitcoin has made the tracking of ransomware attackers more difficult, the amount of ransomware attacks against personal computers and enterprise production servers is increasing rapidly. The ransomware has a wide range of influence and spreads all over the world. It is affecting many industries including internet, education, medical care, traditional industry, etc. This paper uses the idea of virus immunity to design an immunization solution for ransomware viruses to solve the problems of traditional ransomware defense methods (such as anti-virus software, firewalls, etc.), which cannot meet the requirements of rapid detection and immediate prevention of new outbreaks attacks. Our scheme includes two parts: server and client. The server provides an immune configuration file and configuration file management functions, including a configuration file module, a cryptography algorithm module, and a display module. The client obtains the immunization configuration file from server in real time, and performs the corresponding operations according to the configuration file to make the computer have an immune function for a specific ransomware, including an update module, a configuration file module, a cryptography algorithm module, a control module, and a log module. This scheme controls mutexes, services, files and registries respectively, to destroy the triggering conditions of the virus and finally achieve the purpose of immunizing a computer from a specific ransomware

Crystal structure, synthesis and characterization of different chromium-based two-dimensional compounds

The field of two dimensional (2D) materials experienced a surge of discoveries after the isolation of graphene. Among these, the transition metal compounds of Molybdenum and tungsten have been the most extensively studied materials after graphene. More recently, their group member chromium has only recently come to the limelight after the discovery of its exciting magnetic properties. As such the body of work surrounding 2D chromium-based materials is growing. Here, we present an up-to-date summary of the chromium 2D materials showing the latest advances in their experimental synthesis, characterization and the applications of 2D Chromium-based compounds. Finally, we conclude with a perspective on the future of 2D chromium-based materials. We believe that this study will be helpful to understand the field of chromium-based 2D compounds

Impact of meteorological factors on the COVID-19 transmission: A multicity study in China

The purpose of the present study is to explore the associations between novel coronavirus disease 2019 (COVID- 19) case counts and meteorological factors in 30 provincial capital cities of China. We compiled a daily dataset including confirmed case counts, ambient temperature (AT), diurnal temperature range (DTR), absolute humidity (AH) and migration scale index (MSI) for each city during the period of January 20th to March 2nd, 2020. First, we explored the associations between COVID-19 confirmed case counts, meteorological factors, and MSI using non-linear regression. Then, we conducted a two-stage analysis for 17 cities with more than 50 confirmed cases. In the first stage, generalized linear models with negative binomial distribution were fitted to estimate city-specific effects of meteorological factors on confirmed case counts. In the second stage, the meta-analysis was conducted to estimate the pooled effects. Our results showed that among 13 cities that have less than 50 confirmed cases, 9 cities locate in the Northern China with average AT below0 °C, 12 cities had average AHbelow4 g/m3, and one city (Haikou) had the highest AH (14.05 g/m3). Those 17 cities with 50 and more cases accounted for 90.6% of all cases in our study. Each 1 °C increase in AT and DTR was related to the decline of daily confirmed case counts, and the corresponding pooled RRs were 0.80 (95% CI: 0.75, 0.85) and 0.90 (95% CI: 0.86, 0.95), respectively. For AH, the association with COVID-19 case counts were statistically significant in lag 07 and lag 014. In addition,we found the all these associations increased with accumulated time duration up to 14 days. In conclusions, meteorological factors play an independent role in the COVID-19 transmission after controlling population migration. Local weather condition with low temperature, mild diurnal temperature range and low humidity likely favor the transmission

In situ fabrication of freestanding single-atom-thick 2D metal/metallene and 2D metal/ metallene oxide membranes: Recent developments

In recent years, two-dimensional (2D) materials have attracted a lot of research interest as they exhibit several fascinating properties. However, outside of 2D materials derived from van der Waals layered bulk materials only a few other such materials are realized, and it remains difficult to confirm their 2D freestanding structure. Despite that, many metals are predicted to exist as 2D systems. In this review, the authors summarize the recent progress made in the synthesis and characterization of these 2D metals, so called metallenes, and their oxide forms, metallene oxides as free standing 2D structures formed in situ through the use of transmission electron microscopy (TEM) and scanning TEM (STEM) to synthesize these materials. Two primary approaches for forming freestanding monoatomic metallic membranes are identified. In the first, graphene pores as a means to suspend the metallene or metallene oxide and in the second, electron-beam sputtering for the selective etching of metal alloys or thick complex initial materials is employed to obtain freestanding single-atom-thick 2D metal. The data show a growing number of 2D metals/metallenes and 2D metal/ metallene oxides having been confirmed and point to a bright future for further discoveries of these 2D materials.Web of Scienceart. no. 210061

Intermetallic Cooperation in Olefin Polymerization Catalyzed by a Binuclear Samarocene Hydride: A Theoretical Study

The cooperative effect in bi- and multinuclear metal complexes is of great interest in catalysis since such a cooperative effect often gives the complexes unique catalytic performance unavailable in mononuclear analogues. However, the related mechanism of bi- and multinuclear cooperative catalysis remained almost unexplored. Herein, the detailed mechanism of ethylene polymerization by a binuclear samarocene hydride complex has been computationally modeled. The results have not only revealed new aspects of the mechanism of olefin insertion reactions but also provided theoretical evidence for electronic communication between the metal centers during the polymerization, where the bridging hydride ligand plays an important role in such an intermetallic cooperation

Computational Studies on the Selective Polymerization of Lactide Catalyzed by Bifunctional Yttrium NHC Catalyst

A theoretical investigation of the ring-opening polymerization (ROP) mechanism of rac-lactide (LA) with an yttrium complex featuring a N-heterocyclic carbine (NHC) tethered moiety is reported. It was found that the carbonyl of lactide is attacked by N(SiMe3)2 group rather than NHC species at the chain initiation step. The polymerization selectivity was further investigated via two consecutive insertions of lactide monomer molecules. The insertion of the second monomer in different assembly modes indicated that the steric interactions between the last enchained monomer unit and the incoming monomer together with the repulsion between the incoming monomer and the ligand framework are the primary factors determining the stereoselectivity. The interaction energy between the monomer and the metal center could also play an important role in the stereocontrol

Mechanistic Insights into the Methylenation of Ketone by a Trinuclear Rare-Earth-Metal Methylidene Complex

Trinuclear rare-earth-metal methylidene (CH₂^2–) complexes are an emerging class of compounds that serve as methylidene transfer agents for methylenation of carbonyl compounds. Herein, the reaction of a trinuclear scandium methylidene complex with acetophenone was used as a model reaction of the multimetallic-cooperating methylidene transfer case, and its detailed mechanism has been investigated by the DFT approach. The analyses of Wiberg bond index, electron occupation, the frontier molecular orbital, and natural charge provide us a clear and comprehensive understanding of the CH₂^2–/O^2– group interchange process assisted by cooperating multimetal sites. The mechanism presented here is markedly different from conventional Wittig and transition-metal-mediated Wittig-type reactions. In addition, the behavior of μ₃-CH₂ in a multinuclear complex system is also demonstrated. This study not only enriches the chemistry of metal Wittig-type reactions but also sheds light on the intermetallic cooperation for methylidene transfer

Mechanistic Investigation on Scandium-Catalyzed C–H Addition of Pyridines to Olefins

This paper reports computational studies on the ortho alkylation of pyridines via C–H addition to olefins catalyzed by cationic half-sandwich rare-earth alkyl species. A detailed mechanism concerning the generation of catalytically active species and C–H addition has been computationally investigated at the molecular and electronic levels. The results support the mechanism based on experiments, which involves the initial generation of a metal pyridyl active species, followed by the coordination and insertion of an olefin and the subsequent pyridine C–H activation by a metal–carbon bond. The <i>o-</i>methyl sp³ C–H activation product of α<i>-</i>picoline has been also calculated, and the results suggest that the sp³ C–H activation product mainly results from the conversion of the sp² C–H activation product of α-picoline rather than from the direct reaction of the cationic species (η⁵-C₅Me₅)­Sc­(CH₂C₆H₄NMe₂<i>-o</i>)⁺ with α-picoline, and such a conversion is reversible. The reaction rate of the whole process is controlled by the generation of active species and an insertion step. The formation of the branched product is both kinetically and energetically favorable over that of the linear product, which is in agreement with the experimental observation. Both steric and electronic factors account for the regioselectivity. An analysis of energy decomposition provides new insights into the stability of the 1-hexene insertion transition states involved in such processes. A comparison between the successive olefin insertion and the C–H activation of pyridine has also been computationally carried out. In addition, it is predicted that the cationic scandium pyridyl species (η⁵-C₅Me₅)­Sc­(MeC₅H₃N)⁺ has a shorter induction period than the initial aminobenzyl analogue (precursor) (η⁵-C₅Me₅)­Sc­(CH₂C₆H₄NMe₂<i>-o</i>)⁺ for the initiation step of ethylene polymerization

Application of Artificial Intelligence in Oncology Nursing: A protocol for a Scoping Review

This scoping review aims to unequivocally identify and evaluate AI technologies that have been developed, tested or implemented in oncology nursing through a comprehensive synthesis of knowledge