Browsing by Author "Sanjay K. Singh"

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A new distribution with monotone and non-monotone shaped failure rate
(ISOSS Publications, 2020) Sandeep K. Maurya; Sanjay K. Singh; Umesh Singh
In the present paper, we propose to use a transformation to get a new class of distribution by using some baseline distribution. We have considered Lindley distribution as baseline model which is a popular model used in the field of reliability and engineering. The proposed model includes various shapes like increasing, decreasing and bathtub failure rates. We have studied its statistical properties along with the maximum likelihood estimation procedure for the estimation of parameters of the proposed model. Lastly, three real data sets are used to compare the suitability of the proposed model over seven other existing models. © 2020, ISOSS Publications. All rights reserved.
Bayesian estimation for inverse weibull distribution under progressive type-II censored data with beta-binomial removals
(Austrian Statistical Society, 2018) Pradeep K. Vishwakarma; Arun Kaushik; Aakriti Pandey; Umesh Singh; Sanjay K. Singh
This paper deals with the estimation procedure for inverse Weibull distribution under progressive type-II censored samples when removals follow Beta-binomial probability law. To estimate the unknown parameters, the maximum likelihood and Bayes estimators are obtained under progressive censoring scheme mentioned above. Bayes estimates are obtained using Markov chain Monte Carlo (MCMC) technique considering square error loss function and compared with the corresponding MLE’s. Further, the expected total time on test is obtained under considered censoring scheme. Finally, a real data set has been analysed to check the validity of the study. © 2018, Austrian Statistical Society. All rights reserved.
Bayesian inference using product of spacings function for Progressive hybrid Type-I censoring scheme
(Taylor and Francis Ltd., 2018) Suparna Basu; Sanjay K. Singh; Umesh Singh
This article is devoted to the development of product of spacings estimator for a Progressive hybrid Type-I censoring scheme with binomial removals. The experimental units are assumed to follow inverse Lindley distribution. We propose a Bayes estimator of associated scale parameter based on the product of spacings function and simultaneously compare it with that obtained under a usual Bayesian estimation procedure. The estimators are obtained under the squared error loss function along with corresponding HP intervals evaluated by using the Markov chain Monte-Carlo technique. The classical product of spacings estimator has also been derived and compared with the maximum likelihood estimator in addition to 95% average asymptotic confidence intervals. The applicability of the proposed methods is demonstrated by analysing a real data of guinea pigs affected with tuberculosis for the considered censoring scheme. © 2017 Informa UK Limited, trading as Taylor & Francis Group.
Calibration approach estimation of the mean in stratified sampling and stratified double sampling
(Taylor and Francis Inc., 2017) N. Nidhi; B.V.S. Sisodia; Subedar Singh; Sanjay K. Singh
Calibration estimation improves the precision of the estimates of population parameters by incorporating specified auxiliary information. A class of calibration estimators has been proposed for estimating the population mean by making use of a set of calibration constraints in stratified sampling. The estimator of variance of the proposed calibration estimator of the mean is derived using a lower level calibration approach. The idea is extended for stratified double sampling. A simulation study is used to evaluate the performances of the proposed estimators by comparing them with the similar estimators developed by Tracy, Singh and Arnab (2003) based on different sets of calibration constraints. © 2017 Taylor & Francis Group, LLC.
Estimation of Inverse Lindley Distribution Using Product of Spacings Function for Hybrid Censored Data
(Springer New York LLC, 2019) Suparna Basu; Sanjay K. Singh; Umesh Singh
This article presents different estimation procedure for inverse Lindley distribution for Type-I hybrid censored data. We have obtained the parameter estimate under both the classical and Bayesian paradigm. In the classical set up, method of Maximum Likelihood(ML) and Maximum Product of spacings (MPS) estimates are obtained along with 95% asymptotic confidence interval. Bayesian estimation is implemented under the assumption of squared error loss function. An alternative Bayesian procedure is also proposed by incorporating the sample information through the spacings function instead of likelihood function. The Bayes estimates are computed using Markov Chain Monte Carlo (MCMC) technique due to their implicit nature. Highest posterior density (HPD) intervals based on these MCMC samples are evaluated and compared in terms of simulated risks. Further, a real data of 72 guinea pigs, infected with tuberculosis is analysed to justify the suitability of the afore-said estimation techniques under the specified censoring scheme. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.
Estimations of the parameters of generalised exponential distribution under progressive interval type-I censoring scheme with random removals
(Austrian Statistical Society, 2017) Arun Kaushik; Aakriti Pandey; Sandeep K. Maurya; Umesh Singh; Sanjay K. Singh
The present article aims to point and interval estimation of the parameters of generalised exponential distribution (GED) under progressive interval type-I (PITI) censoring scheme with random removals. The considered censoring scheme is most useful in those cases where continuous examination is not possible. Maximum likelihood, expectationmaximization and Bayesian procedures have been developed for the estimation of parameters of the GED, based on a PITI censored sample. Real datasets have been considered to illustrate the applicability of the proposed work. Further, we have compared the performances of the proposed estimators under PITI censoring to that of the complete sample. © 2017, Austrian Statistical Society. All rights reserved.
Fructose-2, 6-bisphosphate associated regulatory enzymes develop in concordance in mice brain during early postnatal life
(2005) Pankaj Pandey; Sanjay K. Singh; Surendra K. Trigun
Fructose-2, 6-bisphosphate (fru-2, 6P2), synthesized by 6-phosphofructo-2-kinase (PFK2), regulates glucose metabolism via modulating phosphofructokinase-1 (PFK1) and fructose-1, 6-bisphosphatase (FBPase1) reciprocally in mammalian tissues. How this control system develops in brain is poorly understood. This article presents the postnatal comparative profiles of fru-2, 6P2 and PFK2 & fru-2, 6P2 dependent regulation of PFK1 and FBPase1 in mice brain. Fru-2, 6P2 and PFK2 activity both attained their adult levels in concordance from day1 to 1wk age. Western blot analysis of mice liver and brain & rat liver PFK2 using anti rat liver PFK2/FBPase2 confirmed that both, mice liver and brain isoforms cross- react efficiently with this antibody. In addition, DEAE-eluted brain fractions from different postnatal ages revealed that 1day mice brain expresses a liver type enzyme (∼55 kDa) that is replaced by an adult brain type protein (∼110 kDa) from 1wk onward ages. As compared to 1day mice, significantly decreased Km values of PFK2 at 1wk-10wk ages also suggest the existence of a kinetically different isoform of this enzyme from 1wk onward ages. In vitro effects of fru-2, 6P2 on partially enriched brain PFK1 and FBPase1 suggest that fru-2, 6P2 dependent respective stimulatory and inhibitory responses of both these enzymes increase progressively from day1 to 3wk age. This is well corroborated with the postnatal age-dependent linear increase in PFK1 and decrease in FBPase1 activities in mice brain. The results suggest that fru-2, 6P2 associated regulatory components develop in concordance in mice brain during early postnatal life. © Universitätsverlag Ulm GmbH 2005.
Fungal diversity notes 1151–1276: taxonomic and phylogenetic contributions on genera and species of fungal taxa
(Springer, 2020) Kevin D. Hyde; Yang Dong; Rungtiwa Phookamsak; Rajesh Jeewon; D. Jayarama Bhat; E. B. Gareth Jones; Ning-Guo Liu; Pranami D. Abeywickrama; Ausana Mapook; Deping Wei; Rekhani H. Perera; Ishara S. Manawasinghe; Dhandevi Pem; Digvijayini Bundhun; Anuruddha Karunarathna; Anusha H. Ekanayaka; Dan-Feng Bao; Junfu Li; Milan C. Samarakoon; Napalai Chaiwan; Chuan-Gen Lin; Kunthida Phutthacharoen; Sheng-Nan Zhang; Indunil C. Senanayake; Ishani D. Goonasekara; Kasun M. Thambugala; Chayanard Phukhamsakda; Danushka S. Tennakoon; Hong-Bo Jiang; Jing Yang; Ming Zeng; Naruemon Huanraluek; Jian-Kui Liu; Subodini N. Wijesinghe; Qing Tian; Saowaluck Tibpromma; Rashika S. Brahmanage; Saranyaphat Boonmee; Shi-Ke Huang; Vinodhini Thiyagaraja; Yong-Zhong Lu; Ruvishika S. Jayawardena; Wei Dong; Er-Fu Yang; Sanjay K. Singh; Shiv Mohan Singh; Shiwali Rana; Sneha S. Lad; Garima Anand; Bandarupalli Devadatha; M. Niranjan; V. Venkateswara Sarma; Kare Liimatainen; Begoña Aguirre-Hudson; Tuula Niskanen; Andy Overall; Renato Lúcio Mendes Alvarenga; Tatiana Baptista Gibertoni; Walter P. Pfliegler; Enikő Horváth; Alexandra Imre; Amanda Lucia Alves; Ana Carla da Silva Santos; Patricia Vieira Tiago; Timur S. Bulgakov; Dhanushaka N. Wanasinghe; Ali H. Bahkali; Mingkwan Doilom; Abdallah M. Elgorban; Sajeewa S. N. Maharachchikumbura; Kunhiraman C. Rajeshkumar; Danny Haelewaters; Peter E. Mortimer; Qi Zhao; Saisamorn Lumyong; Jianchu Xu; Jun Sheng
Fungal diversity notes is one of the important journal series of fungal taxonomy that provide detailed descriptions and illustrations of new fungal taxa, as well as providing new information of fungal taxa worldwide. This article is the 11th contribution to the fungal diversity notes series, in which 126 taxa distributed in two phyla, six classes, 24 orders and 55 families are described and illustrated. Taxa in this study were mainly collected from Italy by Erio Camporesi and also collected from China, India and Thailand, as well as in some other European, North American and South American countries. Taxa described in the present study include two new families, 12 new genera, 82 new species, five new combinations and 25 new records on new hosts and new geographical distributions as well as sexual-asexual reports. The two new families are Eriomycetaceae (Dothideomycetes, family incertae sedis) and Fasciatisporaceae (Xylariales, Sordariomycetes). The twelve new genera comprise Bhagirathimyces (Phaeosphaeriaceae), Camporesiomyces (Tubeufiaceae), Eriocamporesia (Cryphonectriaceae), Eriomyces (Eriomycetaceae), Neomonodictys (Pleurotheciaceae), Paraloratospora (Phaeosphaeriaceae), Paramonodictys (Parabambusicolaceae), Pseudoconlarium (Diaporthomycetidae, genus incertae sedis), Pseudomurilentithecium (Lentitheciaceae), Setoapiospora (Muyocopronaceae), Srinivasanomyces (Vibrisseaceae) and Xenoanthostomella (Xylariales, genera incertae sedis). The 82 new species comprise Acremonium chiangraiense, Adustochaete nivea, Angustimassarina camporesii, Bhagirathimyces himalayensis, Brunneoclavispora camporesii, Camarosporidiella camporesii, Camporesiomyces mali, Camposporium appendiculatum, Camposporium multiseptatum, Camposporium septatum, Canalisporium aquaticium, Clonostachys eriocamporesiana, Clonostachys eriocamporesii, Colletotrichum hederiicola, Coniochaeta vineae, Conioscypha verrucosa, Cortinarius ainsworthii, Cortinarius aurae, Cortinarius britannicus, Cortinarius heatherae, Cortinarius scoticus, Cortinarius subsaniosus, Cytospora fusispora, Cytospora rosigena, Diaporthe camporesii, Diaporthe nigra, Diatrypella yunnanensis, Dictyosporium muriformis, Didymella camporesii, Diutina bernali, Diutina sipiczkii, Eriocamporesia aurantia, Eriomyces heveae, Ernakulamia tanakae, Falciformispora uttaraditensis, Fasciatispora cocoes, Foliophoma camporesii, Fuscostagonospora camporesii, Helvella subtinta, Kalmusia erioi, Keissleriella camporesiana, Keissleriella camporesii, Lanspora cylindrospora, Loratospora arezzoensis, Mariannaea atlantica, Melanographium phoenicis, Montagnula camporesii, Neodidymelliopsis camporesii, Neokalmusia kunmingensis, Neoleptosporella camporesiana, Neomonodictys muriformis, Neomyrmecridium guizhouense, Neosetophoma camporesii, Paraloratospora camporesii, Paramonodictys solitarius, Periconia palmicola, Plenodomus triseptatus, Pseudocamarosporium camporesii, Pseudocercospora maetaengensis, Pseudochaetosphaeronema kunmingense, Pseudoconlarium punctiforme, Pseudodactylaria camporesiana, Pseudomurilentithecium camporesii, Pseudotetraploa rajmachiensis, Pseudotruncatella camporesii, Rhexocercosporidium senecionis, Rhytidhysteron camporesii, Rhytidhysteron erioi, Septoriella camporesii, Setoapiospora thailandica, Srinivasanomyces kangrensis, Tetraploa dwibahubeeja, Tetraploa pseudoaristata, Tetraploa thrayabahubeeja, Torula camporesii, Tremateia camporesii, Tremateia lamiacearum, Uzbekistanica pruni, Verruconis mangrovei, Wilcoxina verruculosa, Xenoanthostomella chromolaenae and Xenodidymella camporesii. The five new combinations are Camporesiomyces patagoniensis, Camporesiomyces vaccinia, Camposporium lycopodiellae, Paraloratospora gahniae and Rhexocercosporidium microsporum. The 22 new records on host and geographical distribution comprise Arthrinium marii, Ascochyta medicaginicola, Ascochyta pisi, Astrocystis bambusicola, Camposporium pellucidum, Dendryphiella phitsanulokensis, Diaporthe foeniculina, Didymella macrostoma, Diplodia mutila, Diplodia seriata, Heterosphaeria patella, Hysterobrevium constrictum, Neodidymelliopsis ranunculi, Neovaginatispora fuckelii, Nothophoma quercina, Occultibambusa bambusae, Phaeosphaeria chinensis, Pseudopestalotiopsis theae, Pyxine berteriana, Tetraploa sasicola, Torula gaodangensis and Wojnowiciella dactylidis. In addition, the sexual morphs of Dissoconium eucalypti and Phaeosphaeriopsis pseudoagavacearum are reported from Laurus nobilis and Yucca gloriosa in Italy, respectively. The holomorph of Diaporthe cynaroidis is also reported for the first time. © 2020, The Author(s).
LC-HRMS metabolomics, isolation, network pharmacology, and molecular docking based evaluation of anti-cancer potential of compounds of Glycyrrhiza glabra L.
(Elsevier B.V., 2025) Sanheeta Chakrabarty; Hitesh Harsukhbhai Chandpa; Nancy Tripathi; Sagar Singh Shyamal; Anindita Bhattacharjee; Sanjay K. Singh; Bharat Goel; Sanju Kumari; Jairam Meena; Venkatnarayanan Ramanathan; Sanjeev Kumar; Shreyans Kumar Jain
Network pharmacology plays a crucial role in drug discovery by identifying target genes and elucidating underlying mechanisms. In the present work, Glycyrrhiza glabra hydroalcoholic extract (GGHE) was subjected to LC-MS phytochemical profiling, followed by in-silico ADME analysis of identified compounds. Various databases like GeneCards, SEA databases, PharmMapper, DisGeNet, SwissTargetPrediction, and STRING were used to find information on target genes, and a network was created using CytoScape. The combination synergy study was done by constructing hierarchical networks. In the LC-MS study, 16 compounds were identified, with 12 passing ADME screening. Enrichment analysis revealed the involvement of various pathways linked to cancer, including EGFR TKI resistance, MAPK, PD-L1/PD-1, proteoglycans, PI3K-Akt, ErbB, and RAS pathways. Synergy studies highlighted mTOR and CHUK gene targets for two compounds. Besides, secondary metabolites were isolated using chromatographic techniques, characterized by NMR, and evaluated for cytotoxicity in human cancer cell lines by MTT assay. Six compounds viz hispaglabridin A, glabrol, isoliquiritin apioside, formononetin, glycyrrhizin, and glabridin were isolated, and most of these were subjected to cytotoxic evaluation. Glabridin showed the highest potency against breast cancer cell lines (MDA-MB-231 and MCF-7) and Network pharmacology suggests Glabrene and Glyinflanin A possesses anti-cancer potential. Thus, the study demonstrates GGHE or its compounds have potential against breast, prostate, and pancreatic cancer. © 2025 Elsevier Ltd
Model suitability analysis of survival time to ovarian cancer patients data
(Natural Sciences Publishing, 2020) Manoj Kumar; Sandeep K. Maurya; Sanjay K. Singh; Umesh Singh; Anurag Pathak
In this paper, we propose a suitable statistical model for survival time of the ovarian cancer patients data. The proposition followed by checking the suitability of twelve lifetime models through different statistical tools like the value of logarithmic of likelihood, Akaike Information Criterion, Kolmogorov-Smirnov distance and Bayesian Information Criterion. The maximum likelihood estimate of the parameters for the considered models has been obtained. Also, the non-parametric procedure has been used to show the validity of the conclusion. © 2020 Natural Sciences Publishing. All rights reserved.
Novel Feed Supplement Improved Metabolic Hormones, Antioxidant Activity, Immune Response and Gene Expression in Postpartum Cows
(Indian journals, 2024) Sandeep K. Chaudhary; Narayan Dutta; Sunil E. Jadhav; Gyanendra Singh; Sanjay K. Singh; Dharmesh Tewari
This study was taken up to assess the efficacy of a customized novel feed supplement on circulating concentration of metabolic hormones, antioxidant activity, immune response and expression of immune related cytokines and genes involved in energy metabolism in early postpartum dairy cows. Postpartum crossbred lactating cows (N=12) were equally and randomly allocated to CON (control) and NFS (Novel Feed Supplement) groups. The cattle in CON group were fed on green fodder and wheat straw-based diet with concentrate mixture, whereas, cattle in NFS group were fed according to CON group with additional novel feed supplement @ 0.25% of BW. The feeding trials was continued from 60 days post-partum to 150 days lactation period (total experimental period was 90 days). Circulating concentration of T3, T4, GH and IGF-1 hormones were significantly (P<0.05) increased in NFS than CON group. The cows fed NFS diet exhibited significantly (P<0.001) enhanced antioxidant activity than their counterpart fed CON diet. Cell mediated immune response and fold expression of immune related cytokines were significantly (P<0.05) improved in NFS fed cows implicating an improved immune response. The fold expression of LEP gene was higher (P<0.001) and GHRL gene was lower (P<0.001) in NFS than CON groups. Thus, it can be concluded that, dietary inclusion of the novel feed supplement @ 0.25% of BW significantly improved the circulating concentration of metabolic hormones, antioxidant activity, immunity and overall health of lactating crossbred cattle during early lactation period. © 2024, Indian journals. All rights reserved.
On the estimation problems for exponentiated exponential distribution under generalized progressive hybrid censoring
(Austrian Statistical Society, 2021) Aakriti Pandey; Arun Kaushik; Sanjay K. Singh; Umesh Singh
In this article, we considered the statistical inference for the unknown parameters of exponentiated exponential distribution based on a generalized progressive hybrid censored sample under classical paradigm. We have obtained maximum likelihood estimators of the unknown parameters and confidence intervals utilizing asymptotic theory. Entropy measures, such as Shannon entropy and Awad sub-entropy, have been obtained to measure loss of information owing to censoring. Further, the expected total time of the test and expected number of failures, which are useful during the execution of an experiment, also have been computed. The performance of the estimators have been discussed based on mean squared errors. Moreover, the effect of choice of parameters, termination time T, and m on the ETTT and ETNFs also have been observed. For illustrating the proposed methodology, a real data set is considered. © 2021, Austrian Statistical Society. All rights reserved.
Quality induced fingerprint identification using extended feature set
(2008) Mayank Vatsa; Richa Singh; Afzel Noore; Sanjay K. Singh
Automatic fingerprint identification systems use level-1 and level-2 features for fingerprint identification. However, forensic examiners utilize inherent level-3 details along with level-2 features. Existing level-3 feature extraction algorithms are computationally expensive to be used for identification. This paper presents a novel algorithm for fast level- 3 feature extraction and identification. The algorithm starts with computing local image quality score using redundant discrete wavelet transform. A fast curve evolution algorithm is then used to extract four level-3 features namely, pores, ridge contours, dots, and incipient ridges. Along with level-1 and level-2 features, these level-3 features are used in a Delaunay triangulation based indexing algorithm. Finally, quality-based likelihood ratio is used to further improve the identification performance. Experiments conducted on a high resolution fingerprint database containing rolled, slap and latent images indicate that the algorithm offers significant benefits for fast fingerprint identification. © 2008 IEEE.
Ruthenium complexes containing pyridine-2-carbaldehyde azine as a synthon in the synthesis of bi-/trimetallic complexes
(Wiley-VCH Verlag, 2008) Sudhakar D. Dwivedi; Ashish K. Singh; Sanjay K. Singh; Sanjeev Sharma; Manish Chandra; Daya S. Pandey
Ruthenium complexes [(η5-C5H5) Ru(PPh3)(κ2-paa)]PF6 (paa = pyridine-2-carbaldehyde azine) and [(η5-C5H 5)Ru(κ1-dppm)-(κ2-paa)]BF 4 [dppm = bis(diphenylphosphanyl)methane] have been employed as a synthon in the synthesis of homo/hetero bi-/trimetallic complexes. It is the uncoordinated N,N-donor site on paa in complex [(η5-C 5H5)Ru(PPh3)-(κ2-paa)]PF 6, and N,N-donor site on paa and pendant phosphorus in [(η5-C5H5)Ru(κ1-dppm) (κ2-paa)]BF4 that allows for their incorporation into bi-/trimetallic systems. The resulting complexes have been characterized by analytical, spectral and electrochemical studies. Molecular structures of homobimetallic complex [(PPh3)(θ5-C 5H5)Ru(μ-paa)Ru(θ6-C 10H14)Cl](PF6)2 and hetero-bimetallic complex [(PPh3)(θ5-C 5H5)-Ru(μ-paa)Rh(θ5-C 5Me5)Cl](PF6)2 have been authenticated crystallographically. Complexes exhibit absorptions throughout the visible region and complicated electrochemical behaviour. Metal-based Ru II/RuIII oxidations in the bimetallic complexes do not vary as in the trimetallic complexes. © Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
Ruthenium(II) polypyridyl complexes: Potential precursors, metalloligands, and topo II inhibitors
(2008) Sanjeev Sharma; Sanjay K. Singh; Daya S. Pandey
Neutral and cationic mononuclear complexes containing both group 15 and polypyridyl ligands [Ru(κ3-tptz)(PPh3)-Cl 2] [1; tptz = 2,4,6-tris(2-pyridyl)-1,3,5-thazine], [Ru(κ3-tptz)(κ2-dppm)CI]BF4 [2; dppm = bis(diphenylphosphino)-methane], [Ru(κ3-tptz)(PPh 3)(pa)]Cl (3; pa = phenylalanine), [Ru(κ3-tptz) (PPh3)(dtc)]Cl (4; dtc = diethyldithiocarbamate), [Ru(κ3-tptz)(PPh3)(SCN)2] (5) and [Ru(κ3-tptz)(PPh3)(N3)2] (6) have been synthesized. Complex 1 has been used as a metalloligand in the synthesis of homo- and heterodinuclear complexes [Cl2(PPh 3)Ru(μ-tptz)Ru-(η6-C6H 6)Cl]BF4 (7), [Cl2(PPh3)Ru(μ- tptz)Ru(η6-C10H14)Cl]PF6 (8), and [Cl2(PPh3)Ru(μ-tptz)Rh(η5-C 5Me5)Cl]BF4 (9). Complexes 7-9 present examples of homo- and heterodinuclear complexes in which a typical organometallic moiety [(η6-C6H6)RuCl]+, [(η6-C10H14)RuCl]+, or [(η5-C5Me5)RhCl]+ is bonded to a ruthenium(II) polypyridine moiety. The complexes have been fully characterized by elemental analyses, fast-atom-bombardment mass spectroscopy, NMR ( 1H and 31P), and electronic spectral studies. Molecular structures of 1-3, 8, and 9 have been determined by single-crystal X-ray diffraction analyses. Complex 1 functions as a good precursor in the synthesis of other ruthenium-(II) complexes and as a metalloligand. All of the complexes under study exhibit inhibitory effects on the Topoisomerase II-DNA activity of filarial parasite Setaria cervi and β-hematin/hemozoin formation in the presence of Plasmodium yoelii lysate. © 2008 American Chemical Society.
Statistical analysis for generalized progressive hybrid censored data from lindley distribution under step-stress partially accelerated life test model
(Austrian Statistical Society, 2021) Aakriti Pandey; Arun Kaushik; Sanjay K. Singh; Umesh Singh
The aim of this paper is to present the estimation procedure for the step-stress partially accelerated life test model under the generalized progressive hybrid censoring scheme. The uncertainties are assumed to be governed by Lindley distribution. The problem with point and interval estimation of the parameters as well as the acceleration factor using maximum likelihood approach for the step-stress partially accelerated life test model has been considered. A simulation study is conducted to monitor the performance of the estimators on the basis of the mean squared error under the considered censoring scheme. The expected total time of the test under an accelerated condition is computed to examine the effects of the parameters on the duration of the test. In addition, a graph of the expected total time of the test under accelerated and un-accelerated conditions is provided to highlight the effect due to acceleration. One real data set has been analyzed for illustrative purposes. © 2021, Austrian Statistical Society. All rights reserved.
Synthetic, spectral and structural studies of ruthenium(II) compounds based on 2,6-diacetylpyridinemonoxime
(2008) Manoj Trivedi; Sanjay K. Singh; Daya S. Pandey; Ru-Qiang Zou; Manish Chandra; Qiang Xu
Reaction of the ruthenium complexes [RuCl2(EPh3)3] (E = P, As), [(η5-C5H5)RuCl(EPh3)2] (E = P, As), [(η5-C5Me5)RuCl(PPh3)2] and [(η5-C9H7)RuCl(PPh3)2] with 2,6-diacetylpyridinemonoxime (dapmoH) have been investigated. Compounds with the formulations [Ru(κ3-dapmoH)Cl(PPh3)2]PF6 (1), [Ru(κ3-dapmoH)Cl(PPh3)2]BF4 (2) and [Ru(κ3-dapmoH)Cl(AsPh3)2]Cl (3) have been isolated and fully characterized by elemental analyses, IR, NMR, electronic, emission spectral and electrochemical studies. Molecular structures of the complexes [Ru (κ3 -dapmoH) Cl (PPh3)2] PF6 · H2 O (1) and [Ru (κ3 -dapmoH) Cl (PPh3)2] BF4 · 1.5 H2 O (2) have been determined by single crystal X-ray diffraction studies. A structural feature of interest for both the compounds is that the counter anions in 1 and 2 play vital role in the self-assembly of cages through intermolecular weak interactions in which water dimers or trimers are encapsulated. Compounds 1 and 2 strongly emit upon excitation at their respective MLCT transitions. © 2007 Elsevier B.V. All rights reserved.
Tuned helical array of RhIII/IrIII Cp* complexes with polypyridyl ligands
(Wiley-VCH Verlag, 2006) Sanjay K. Singh; Manish Chandra; Santosh K. Dubey; Daya S. Pandey
Reactions of the chloro-bridged dimeric complexes [{(η5- C5Me5)M(μ-Cl)Cl}2] (M = Rh, Ir) with the polypyridyl ligands 2,3-di(2-pyridyl)pyrazine (dpp) and 2,4,6-tri(2-pyridyl)-1, 3,5-triazine (tptz) in the presence of ammonium tetrafluoroborate gave the mononuclear complexes [(η5-C5Me5) MCl(κ2-dpp)]BF4 [M = Rh (1), Ir (2)] and [(η5-C5Me5)MCl(κ2-tptz)] BF4 [M = Rh (3), Ir (4)]. The complexes have been characterised by elemental analysis, FAB-MS, ESMS, IR, NMR, electronic and emission spectroscopic studies and the molecular structures of 1, 2 and 3 have been crystallographically determined. Structural studies on the complexes revealed the presence of helical superstructures resulting from C-H⋯X (X = N, F, Cl and π) interactions. © Wiley-VCH Verlag GmbH & Co. KGaA, 2006.