DIVISIBILITY TESTS FOR SMARANDACHE SEMIGROUPS

Two Divisibility Tests for Smarandache semigroups are given. Further, the notion of divisibility of elements in a semigroup is applied to characterize the Smarandache semigroups. Examples are provided for justification

ON SMARANDACHE RINGS

It is proved that a ring R in which for every x ∈ R there exists a (and hence the smallest) natural number n(x) > 1 such that xn(x) = x is always a Smarandache Ring. Two examples are provided for justification

Studying Ransomware Attacks Using Web Search Logs

Cyber attacks are increasingly becoming prevalent and causing significant damage to individuals, businesses and even countries. In particular, ransomware attacks have grown significantly over the last decade. We do the first study on mining insights about ransomware attacks by analyzing query logs from Bing web search engine. We first extract ransomware related queries and then build a machine learning model to identify queries where users are seeking support for ransomware attacks. We show that user search behavior and characteristics are correlated with ransomware attacks. We also analyse trends in the temporal and geographical space and validate our findings against publicly available information. Lastly, we do a case study on 'Nemty', a popular ransomware, to show that it is possible to derive accurate insights about cyber attacks by query log analysis.Comment: To appear in the proceedings of SIGIR 202

Physiological antioxidant system and oxidative stress in stomach cancer patients with normal renal and hepatic function

Role of free radicals has been proposed in the pathogenesis of many diseases. Gastric cancer is a common disease worldwide, and leading cause of cancer death in India. Severe oxidative stress produces reactive oxygen species (ROS) and induces uncontrolled lipid peroxidation. Albumin, uric acid (UA) and Bilirubin are important physiological antioxidants. We aimed to evaluate and assess the role of oxidative stress (OS) and physiological antioxidant system in stomach cancer patients. Lipid peroxidation measured as plasma Thio Barbituric Acid Reactive substances (TBARS), was found to be elevated significantly (p=0.001) in stomach cancer compared to controls along with a decrease in plasma physiological antioxidant system. The documented results were due to increased lipid peroxidation and involvement of physiological antioxidants in scavenging free radicals but not because of impaired hepatic and renal functions

Robust Estimation of Tone Break Indices from Speech Signal using Multi-Scale Analysis and their Applications

The aim of this study is to develop robust algorithm to automatically detect the Tone and Break Indices(ToBI) from the speech signal and explore their applications. iLAST was introduced to analyze the acoustic and prosodic features to detect the ToBI indices. Both expert and data driven rules were used to improve the robustness. The integration of multi-scale signal analysis with rule-based classification has helped in robustly identifying tones that can be used in applications, such as identifying Vowel triangle, emotions from speech etc. Empirical analyses using labeled dataset were performed to illustrate the utility of the proposed approach. Further analyses were conducted to identify the inefficiencies with the proposed approach and address those issues through co-analyses of prosodic features in identifying the major contributors to robust detection of ToBI. It was demonstrated that the proposed approach performs robustly and can be used for developing a wide variety of applications

Investigation Of Stoichiometric And Catalytic Palladium Mediated Reactions

This dissertation describes the investigation of stoichiometric and catalytic transformations involving Pd(II) compounds. The first two parts of the dissertation are focused on the preparation, characterization and application of the well-known group of Pd(II) derivatives called cyclopalladated complexes (CPCs). Specifically, N,N-dimethylhydrazone of D-camphor (I.1) was obtained as the single E isomer in 80% yield by treating the enantiopure ketone with N,N-dimethylhydrazine in the presence of an equimolar amount of p-TSA.H2O in ethanol. Direct cyclopalladation of hydrazone I.1 was accomplished at the C(3)H2 group using Pd(MeCN)2Cl2 and NaOAc in MeCN at the reflux temperature. The product of the reaction, dinuclear cyclopalladated complex (I.2), was isolated in 89% yield as a mixture of diastereoisomers, which differ by the absolute configuration of the chiral carbon bound to the metal. Compound I.2 was converted to the mononuclear complex I.3 by treating the dimer with PPh3. Compound I.3 was a mixture of two diastereomers with the Pd atom either in the endo or exo position of the bornane scaffold. Isomers of complex I.3 were partly separated by column chromatography to obtain samples of endo-I.3 and exo-I.3 with 96% and 86% de, respectively. The structures of two diastereomers, endo-I.3 and exo-I.3, were supported by 1H, 13C{1H}, 31P{1H} and 1D NOE NMR spectra and X-ray crystallographic data.The dimeric complex I.2 (named as II.12 in Chapter II) and five known (sp2)C,N and (sp3)C,N cyclopalladated complexes (II.1, II.4, II.6, II.8, and II.10) derived from N,N-dimethylbenzylamine, 4,4-dimethyl-2-phenyl-2-oxazoline, 2-tert-butyl-2,2-dimethyl-2- oxazoline, O-methyloxime of D-camphor, and 8-methylquinoline were used in C–C bond formation reactions with aryl, benzyl and allylboronic acids or esters. Two protocols for a C–C coupling were developed; both involve the use of a base and the conversion of dimeric cyclopalladated complexes to the mononuclear derivatives with PPh3 as an auxiliary ligand. The (sp2)C–(sp2)C bond formation was successfully achieved by reacting complexes PPh3-II.1 and PPh3-II.4 with ArB(OH)2 in acetone at 60 oC in the presence of Cs2CO3, and the corresponding products II.3 and III.5 were isolated in 73–90%. Reactions of (i) (sp3)C,N complexes PPh3-II.6, PPh3-II.8, and PPh3-II.10 with ArB(OH)2 (Ar = Ph, p-NO2C6H4, p-MeOC6H4, 8-quinolyl and 2-pyridyl) and (ii) (sp2)C,N palladacycle PPh3-II.4 with pinacol esters of allyl- and benzylboronic acids occurred in a refluxing 4:1 mixture of dioxane-water in the presence of K3PO4 and afforded (sp2)C–(sp3)C coupling products II.7, II.9, II.11 and II.15 in 46–89% yield. Compounds II.16b–II.18b with an (sp3)C–(sp3)C bond were isolated in 67, 38, and 17% in the reactions of pinacol ester of benzylboronic acid with (sp3)C,N palladacycles PPh3-II.6, PPh3-II.8, and PPh3-II.10, respectively. The stereoselectivity of the transformation was investigated using reactions of p-NO2C6H4B(OH)2 with two diastereomeric complexes having different absolute configurations of the chiral center attached to the metal, (1R,2S,4R,Z)-II.12 and (1R,2R,4R,Z)-II.12. Both reactions yielded the same isomer, (1R,3R,4R,Z)-II.13b. The X-ray crystallographic data of (1R,3R,4R,Z)-II.13b were obtained. In the third part of the dissertation, the Pd-catalyzed arylation of arylboronic acids with triarylphosphines was investigated. Various parameters of this transformation, such as the oxygen presence, choice of solvent, temperature, palladium source, bases and oxidants, were tested and the optimal conditions of the aryl transfer were determined. The effect of electron-withdrawing and electron-donating substituents on the aryl groups of both reactants was also studied. The unusual transfer of the acetate group from Pd(OAc)2 to p-nitrophenylboronic acid in the presence of PAr3 was observed. A plausible mechanism of the Pd-catalyzed aryl group transfer from PAr3 to the arylboronic acid was proposed

Changes in the electronic structure and properties of graphene induced by molecular charge-transfer

Interaction with electron donor and acceptor molecules such as aniline and nitrobenzene brings about marked changes in the Raman spectrum and the electronic structure of graphene, prepared by the exfoliation of graphitic oxide.Comment: 13 pages, 4 figure