Cholesterol thiosalicylate, a novel cholesterol conjugate its synthesis experimental studies conformational analysis chemical reactivity intermolecular interaction and first order hyperpolarizability

2019 ◽  
Vol 1195 ◽  
pp. 231-245
Author(s):  
Sangeeta Srivastava ◽  
Sadaf Aleem ◽  
Nadeem Ahmed Ansari
Keyword(s):  
Conformational Analysis ◽  
Intermolecular Interaction ◽  
Chemical Reactivity ◽  
Experimental Studies ◽  
First Order

scholarly journals Deeper Insights into Conformational Analysis of cis-Butene and 1-Alkenes as Monomers and Dimers: QTAIM, NCI, and DFT Approach

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Caio L. Firme
Keyword(s):  
Hydrogen Bonding ◽  
Conformational Analysis ◽  
Intermolecular Interaction ◽  
Boiling Point ◽  
Experimental Studies ◽  
Physical Property ◽  
Repulsive Interaction ◽  
Methyl Groups ◽  
Stable Conformer ◽  
Linear Relationships

A few theoretical and experimental studies have been done so far about the properties and the conformational analysis of alkenes as monomers and dimers. Deeper insights into the conformational analysis of monomers and dimers of alkenes and the relation with boiling point are done in this work. In low-lying cis-butene, there is no repulsive interaction between methyl groups but there is an attractive hydrogen-hydrogen bonding. In monomers of 1-alkenes, the most stable conformer has bent-inward geometry which favors the π bond interaction with methyl/methylene hydrogen/carbon atoms. Conversely, each alkene’s molecule in the corresponding most stable alkene’s dimer has a straight, zig-zag geometry. Two straight, zig-zag alkene’s molecules in the corresponding most stable dimer have only one type of intermolecular interaction (hydrogen-hydrogen bonding). As a consequence, very good linear relationships between a physical property (such as boiling point) and theoretical parameters are obtained.

On the Chemical Reactivity of the Phytochrome Chromophore in the Pr and Pfr Form

1985 ◽  
Vol 40 (3-4) ◽  
pp. 215-218 ◽  
Author(s):  
Fritz Thümmler ◽  
Peter Eilfeld ◽  
Wolfhart Rüdiger ◽  
Doo-Khil Moon ◽  
Pill-Soon Song
Keyword(s):  
Reaction Kinetics ◽  
Rate Constants ◽  
Chemical Reactivity ◽  
Order Reaction ◽  
First Order Reaction ◽  
Limiting Factor ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Pseudo First Order ◽  
The Difference

The reactivity of the phytochrome chromophore and related tetrapyrroles towards ozone and tetranitromethane was investigated. Both oxidizing reagents cause bleaching of the main absorp­tion band of the pigment. The rate constants for this bleaching were determined under conditions of pseudo first order reaction kinetics. The rate constants for the reaction with ozone are similar for native phytochrome and for freely accessible tetrapyrroles (biliverdin, small chromopeptides from phytochrome) indicating that accessibility is not the limiting factor for the reaction with ozone. Under a variety of conditions, the Pfr chromophore reacts by about 10% faster than the Pr chromophore. This may reflect the true difference in reactivity. The rate constants for the reaction with tetranitromethane are much larger for biliverdin, bilirubin and small chromopeptides from phytochrome than for native phytochrome. The limiting factor for this reaction in native phytochrome therefore is the accessibility of the chromophore by the reagent. Previous conclusions on the difference in exposure of the tetrapyrrole chromophore in Pr and Pfr are confirmed.

Sustainable wastewater management technology for tourism in Thailand: case and experimental studies

2019 ◽  
Vol 79 (10) ◽  
pp. 1977-1984
Author(s):  
W. Liamlaem ◽  
L. Benjawan ◽  
C. Polprasert
Keyword(s):  
Kinetic Constant ◽  
Experimental Studies ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Wastewater Management ◽  
Order Kinetic ◽  
First Order ◽  
Treated Effluent ◽  
Management Technology ◽  
Pre Treatment

Abstract Thailand has adopted the concept of eco-tourism as a protocol to protect environmental resources. One of the key factors in enabling the achievement of this goal is the improvement of the quality of effluent from those homestays and resorts which still lack efficient on-site wastewater treatment. This research utilized case studies of subsurface flow constructed wetlands (SFCWs), planted mainly with the Indian shot (Canna indica L.), which were designed to treat wastewaters at three resorts located in Amphawa District, Samut Songkram Province in central Thailand. The results showed that the treated effluent was of sufficient quality to meet the building effluent standards Type C, which require the concentrations of biological oxygen demand (BOD), total Kjeldahl nitrogen (TKN) and suspended solids (SS) to be less than 40, 40 and 50 mg/L, respectively. In addition, the first-order kinetic constants for the design and operation of SFCWs were determined. For treating wastewater containing organic substances, with no prior pre-treatment, the first-order kinetic constant of 0.24 1/d can be applied to predict effluent quality. For treating other types of domestic wastewater, a first-order kinetic constant in the range 0.40–0.45 1/d can be used when sizing and operating SFCWs. This research highlights the great potential of SFCWs as a sustainable wastewater management technology.

scholarly journals In-silico study of antituberculous activity of Zn-pyrazinamide in pyrazinamidase

2020 ◽  
Author(s):  
Jesus Antonio Alvarado-Huayhuaz ◽  
Wilmar Puma-Zamora ◽  
Ana Cecilia Valderrama-Negrón
Keyword(s):  
In Silico ◽  
Chemical Reactivity ◽  
Experimental Studies ◽  
New Drugs ◽  
In Silico Study ◽  
Three Stages ◽  
Dynamics Simulations ◽  
Antituberculous Activity ◽  
Tuberculosis Activity ◽  
Pyrazinoic Acid

Tuberculosis is caused by Mycobacterium tuberculosis and is one of the leading causes of death. Treatment with pyrazinamide depends on the formation of the bioactive species, pyrazinoic acid (POA), catalyzed by the enzyme pyrazinamidase (PZAse). New mutant strains show resistance to PZA, therefore, it is necessary to search for new drugs. Metallodrugs can offer a synergistic effect on the biological activity of the metal and the drug. Recent studies by our group show anti-tuberculosis activity of pyrazinamide coordinated with Zn, however, the mechanism of action is unknown. In this work, an in-silico study was carried out in three stages: Quantum mechanical, molecular docking and molecular dynamics simulations. ZnPZA (Egap = 4.12 eV) presented greater chemical reactivity than PZA (Egap = 4.97 eV). Greater binding energy was found in ZnPZA-PZAse (-6.98 kcal/mol) than in PZA-PZAse (-6.48 kcal/mol). RMSD and RMSF show stability in PZA-PZAse and ZnPZA-PZAse dockings. Hydrogen bonds interaction of ZnPZA with the catalytic amino acids Asp8 and Lys96 occurs for 83 and 40 ns, respectively. It is concluded that ZnPZA could serve as a transporter of PZA to the active site of PZAse, to promote the production of POA and the antituberculous effect; however, further experimental studies are needed.

scholarly journals Numerical and Experimental Analysis of the Dynamic Behavior of Piezoelectric Stiffened Composite Plates Subjected to Airflow

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Nguyen Thai Chung ◽  
Nguyen Ngoc Thuy ◽  
Duong Thi Ngoc Thu ◽  
Le Hai Chau
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Behavior ◽  
Degrees Of Freedom ◽  
Plate Theory ◽  
Experimental Studies ◽  
Composite Plates ◽  
Theoretical Method ◽  
First Order ◽  
Element Method

In this paper, the authors present results on dynamic behavior analysis of the stiffened composite plate with piezoelectric patches under airflow by finite element method and experimental study. The first-order shear deformation plate theory and nine-noded isoparametric piezoelectric laminated plate finite element with five elastic degrees of freedom at each node and one electric degree of freedom per element per piezoelectric layer were used in the dynamic analysis of plates by finite element method. The modern equipment was used in the dynamic behaviors analysis of plates subjected to airflow load by experimental method. In this study, the results of the theoretical method have been compared with experimental studies.

scholarly journals Reactions of Organic Disulfides and Gold(I) Complexes

1999 ◽  
Vol 6 (4-5) ◽  
pp. 247-253 ◽  
Author(s):  
Melanie DiLorenzo ◽  
Shantheni Ganesh ◽  
Lily Tadayon ◽  
Jinhua Chen ◽  
Mitchell R. M. Bruce ◽  
...  
Keyword(s):  
Exchange Reaction ◽  
Chemical Reactivity ◽  
Conductivity Measurements ◽  
Exchange Reactions ◽  
Disulfide Exchange ◽  
First Order ◽  
Mixed Disulfide ◽  
Ionic Mechanisms ◽  
Thiolate Complexes ◽  
Gold Thiolate

Gold-thiolate/disulfide exchange reactions of (p-SC6H4Cl)2 with Ph3PAu(SC6H4CH3) , dppm(AuSC6H4CH3)2, and dppe(AuSC6H4CH3)2 were investigated. The rate of reactivity of the gold-thiolate complexes with (p-SC6H4Cl)2 is: dppm(AuSC6H4CH3)2>> dppe(AuSC6H4CH3)2>Ph3PAu(SC6H4CH3). This order correlates with conductivity measurements and two ionic mechanisms have been evaluated. H1 NMR experiments demonstrate that in the reaction of dppm(AuSC6H4CH3)2 with (p-SC6H4Cl)2, the mixed disulfide, ClC6H4SSC6H4CH3, forms first, followed by the formation of (p-SC6H4CH3)2. The rate law is first order in (pp-SC6H4Cl)2 and partial order in dppm(AuSC6H4CH3)2. Results from electrochemical and chemical reactivity studies suggest that free thiolate is not involved in the gold-thiolate/disulfide exchange reaction. A more likely source of ions is the dissociation of a proton from the methylene backbone of the dppm ligand which has been shown to exchange with D2O. The implications of this are discussed in terms of a possible mechanism for the gold-thiolate/disulfide exchange reaction.

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