21 research outputs found
Reactions of (PCP)Ir complexes with small molecules:
No full textIridium pincer complexes (R4PCP)IrHn (PCP=[k3-2,6-C6H3(CH2PR2)]) are effective catalysts for the dehydrogenation of alkanes. We wished to design pincer ligands in which the set of phosphinoalkyl groups would offer (a) maximal steric "protection" against cluster-formation (b) minimal hindrance to C-H addition, and (c) resistance to decomposition and self-dehydrogenation (unlike iPr groups). Thus, we have synthesized iridium complexes of ligands tBu3MePCP ([C6H3(CH2PtBuMe)(CH2PtBu2]). (tBu3MePCP)IrH4 (1) shows more efficiency in dehydrogenation of alkanes than either
(tBu4PCP)IrHn or (iPr4MePCP)IrHn. (tBu3MePCP)IrH4 was also found to be a very effective catalyst in alkane metathesis.
Although isocyanides are important building blocks in organic synthesis, their commercial availability is limited compared to other chemicals. (PCP)Ir complexes react with different secondary methyl amines and at ambient temperature to form
corresponding iridium isocyanide complexes (PCP)Ir(H)(H)(CNR), 3-1 (a-e) which react with CO forming (PCP)Ir(CO) to liberate the corresponding isocyanide.
The addition of PhCCH to highly stable complexes, (PCP)IrL (L = CO, CNR), is challenging. (PCP)IrL (L = CO, CNR) complexes react with PhCCH in presence of acid to form complex (PCP)Ir(CO)(H)(CCPh) (5-3) and (PCP)Ir(CNBz)(H)(CCPh) (5-1), respectively, in which hydride and acetylide group are trans to each other. The reaction proceeds via the cationic intermediate [(PCP)Ir(CO)(H)]+. Solid-supported catalysts have significant advantages over homogeneous systems, particularly with respect to product-catalyst separation. We have investigated several routes to the development of supported pincer-ligated iridium catalysts. The p-dimethylamino- substituted PCP complex is found to bind strongly to alumina while maintaining the same high activity (or even slightly greater) for alkane-dehydrogenation as found in the solution phase.
A broad range of (PCP)Ir complexes with widely varying steric and electronic effects have been synthesized and studied including (PCP)IrL, (PCP)Ir(H)(H)L and PCP)Ir(H)(Cl)L, (L = various P- and N-donors, N2, various olefins). The relative thermodynamics of these adducts have been detected by equilibrium measurements and calculated using DFT. Precursors of "(PCP)Ir" cleaves sp3 C--O bonds of various esters (RCO2R1, R1= alkyl) to give (PCP)Ir(R1)(O2CR) or, in cases where R1 has a b-hydrogen, (PCP)Ir(H)(O2CR) plus the corresponding alkene derived from R1.Ph.D.Includes bibliographical referencesby Sabuj Kumar Kund
Molecular Detection and Antibiotic Resistance of Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio alginolyticus from Shrimp (Penaeus monodon) and Shrimp Environments in Bangladesh
No full textSome Vibrio species can cause food-borne diseases in humans, including cholera, vomiting, septicemia, and gastroenteritis, which are associated with the consumption of contaminated seafood products. The study was conducted to detect antimicrobial-resistant Vibrio species in shrimp and shrimp environments in Bangladesh. Samples of shrimp (n = 50), water (n = 50), and mud (n = 50) were collected aseptically from 50 different shrimp culture ponds in the Khulna region of Bangladesh. Identification of Vibrio species was based on cultural and staining characteristics, biochemical tests, and polymerase chain reaction (PCR). Antimicrobial resistance profiles were determined using a disk diffusion assay. By PCR, Vibrio isolates were found in 34% (95% CI: 26.9%–41.9%) of the samples, of which the detection rate was significantly higher in shrimp (54%), compared to mud (26%) and water (22%). Moreover, V. cholerae, V. parahaemolyticus, and V. alginolyticus were detected in 24.7%, 15.3%, and 4% of the samples, respectively. Among them, the detection rate of V. cholerae and V. alginolyticus was significantly higher in shrimp samples than in other samples. V. parahaemolyticus was also higher in the shrimp samples, but the difference was not statistically significant. Vibrio isolates showed high to moderate resistance (92.2%–15.7%) to ampicillin, amikacin, cefotaxime, tetracycline, ceftazidime, gentamicin, nalidixic acid, levofloxacin, and ciprofloxacin, and low resistance (3.9%) to imipenem, meropenem, chloramphenicol, and trimethoprim-sulfamethoxazole. Interestingly, 52.9% of the isolates were multidrug resistant, and the multiple antibiotic resistance index was up to 1.0. To our knowledge, this is the first study in Bangladesh detecting these three Vibrio species (V. parahaemolyticus, V. alginolyticus, and V. cholerae) from shrimp and shrimp environments by molecular approach in the same study. These findings reveal the alarmingly high occurrence of antimicrobial-resistant Vibrio species in shrimp and shrimp environments, which should be of concern to both the shrimp industry and public health management
Inclusion of the economically backward students: Scope and tenet of Indian school libraries
No full textThe study aims to find out how far a school library can contribute in the issue of inclusion of the economically backward class students. Meanwhile the author has opined three major issues: Economical, Psychological and Societal as the reasons behind the school dropouts in India; while theoretical analyses have unveiled that the school library has enough scope and potential to reduce the dropout rate by offering several innovative approaches. Further, the author has investigated the reality and forwarded ten unique approaches (broadly classified into Library beyond school, Increase the reading habit and Empowerment of the student) which could be fruitful to impede the dropout rates in school education and also framed a flowchart to describe the steps of the process. The study shows that the approaches are well construct and self-explanatory and proper implications of those ideas can uplift the literacy rate. Later, two cases are being cited in the study to understand the applicability of those initiatives. The result shows that through the appropriate application of the ideas the dropout rates have decreased in both the cases
Effect of Common Extraneous Citation Optimizing Factors on Journal Impact Indicators
No full textThis study examines nineteen Scopus index Library and Information Science (LIS) journals to understand the individual as well as unified effects of three optimizing factors such as Author self-citation (ASC), Journal self-citation (JSC) and Recitation (RC) on three popular impact indicators i.e., 2-year JIF, 3-year JIF and JII. Authors found that ASC and JSC have noticeable effects on these impact indicators. Further, it is observed that these impact indicators exhibit very poor correlation among them when their values are deduced from raw citation counts, though all of them express simple arithmetic mean values. The authors concluded that a more refined method that can automatically exclude the effect of these optimizing factors in their derivation may be needed for a fair assessment of a journal’s relative impact in scholarly communication
Nexus between Economic Policy Uncertainty and Bank Liquidity Creation: Moderating Role of Bank Regulations and Credit Risk
No full textPurpose: This paper analyzes the effects of economic policy uncertainty (EPU), bank regulations, and credit risk on the asset and liability sides of liquidity creation in developed and developing countries.
Methods: The sample comprises 100 companies in developed and developing countries from 2015 to 2021. We used a dynamic Generalized Method of Moments (GMM) estimator to test the hypothesis. We also performed the Sargan test of over-identification or J-statistics to check the validity of instruments in the GMM model. Additionally, we conducted a robustness test on our analysis based on average assets and average capital.
Results: We find that Economic Policy Uncertainty (EPU) significantly negatively impacts asset-side liquidity creation in developed and developing countries. However, EPU significantly positively impacts liability-side liquidity creation only in developed countries. Interestingly, higher credit risk can effectively counteract the adverse effects of EPU on asset-side liquidity creation and encourage a positive impact on liability-side liquidity creation in developed and developing countries. Moreover, stricter bank regulations, including activity restriction and capital stringency, can weaken the negative effects of EPU on asset-side liquidity creation in developed and developing countries. However, we do not find any significant effect of higher bank regulations on the relationship between liability-side liquidity creation and EPU.
Implications: Since financial institutions can make riskier decisions to keep their businesses going in an uncertain economy, regulators need to act in advance to restore confidence in credit growth and financial resilience. The government should assess the short-term and long-term consequences of any policy implications.
Originality: While most studies concentrate on total liquidity creation from a cross-country perspective, our study provides new evidence by breaking down liquidity creation into asset-side and liability-side liquidity creation and examining the research separately in developed and developing countries
Quantification of scaling exponent with Crossover type phenomena for different types of forcing in DC glow discharge plasma
No full textInvestigation and quantification of nonlinearity using surrogate data in a glow discharge plasma
No full textInterplay of transitions between oscillations with emergence of fireballs and quantification of phase coherence, scaling index in a magnetized glow discharge plasma in a toroidal assembly
No full textHysteresis of fluctuation dynamics associated with a fireball in a magnetized glow discharge plasma in a currentless toroidal assembly
No full textInvestigation and quantification of Phase coherence index for different types of forcing in DC glow discharge plasma
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