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Kumar, Shiv,Khan, S.A.,Alam, Ozair,Azim, Rizwan,Khurana, Atul,Shaquiquzzaman, M.,Siddiqui, Nadeem,Ahsan, Waquar Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.7
4-Chlorotetrazolo[1,5-a]quinoxaline (III) was synthesized by azide (2+3) cycloaddition of 2,3-dichloroquinoxaline (II). Compound (III) on further refluxing with hydrazine hydrate furnished 4-hydrazinotetrazolo[1,5-a]quinoxaline (IV). Further refluxing of (IV) with different aromatic aldehydes in methanol yielded corresponding Schiff's bases V(a-j). Various 4-aminotetrazolo[1,5-a]quinoxaline based azetidinones VII(a-j) were synthesized by stirring the compounds V(a-j), at low temperature, with equimolar mixture of chloroacetylchloride & triethylamine in dry benzene, while 4-aminotetrazolo[1,5-a]quinoxaline based thiazolidinones VIII(a-j) were synthesized by refluxing Schiff's bases V(a-j) with thioglycolic acid in oil-bath. The structures of all the compounds were confirmed on the basis of $^1H$-NMR & FT-IR spectral data. All the newly synthesized compounds were screened for in-vitro antimicrobial activity against E. coli, S. aureus, K. pneumoniae & P. aeruginosa & antifungal activity against C. albicans. Few of them have exhibited the promising activity.
Shiv Kumar,S. A. Khan,Ozair Alam,Rizwan Azim,Atul Khurana,M. Shaquiquzzaman,Nadeem Siddiqui,Waquar Ahsan 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.7
4-Chlorotetrazolo[1,5-a]quinoxaline (III) was synthesized by azide (2+3) cycloaddition of 2,3-dichloroquinoxaline (II). Compound (III) on further refluxing with hydrazine hydrate furnished 4-hydrazinotetrazolo[1,5-a]quinoxaline (IV). Further refluxing of (IV) with different aromatic aldehydes in methanol yielded corresponding Schiff’s bases V(a-j). Various 4-aminotetrazolo[1,5-a]quinoxaline based azetidinones VII(a-j) were synthesized by stirring the compounds V(a-j), at low temperature, with equimolar mixture of chloroacetylchloride & triethylamine in dry benzene, while 4-aminotetrazolo[1,5-a]quinoxaline based thiazolidinones VIII(a-j) were synthesized by refluxing Schiff’s bases V(a-j) with thioglycolic acid in oil-bath. The structures of all the compounds were confirmed on the basis of ^1H-NMR & FT-IR spectral data. All the newly synthesized compounds were screened for in-vitro antimicrobial activity against E. coli, S. aureus, K. pneumoniae & P. aeruginosa & antifungal activity against C. albicans. Few of them have exhibited the promising activity.
M.Z.A. Rafiquee,Masoom R. Siddiqui,H.N. Haque,M. Shamsul Ola,Hamad A. Al-Lohedan,Z.A. ALOthman,Saikh M. Wabaidur 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.34 No.-
Reduction of molecular oxygen by 2-mercaptoethanol in the presence of cobalt(II)histidine is described. Cobalt(II)histidine complex forms dinuclear 2:1 (Co:O2) complex with molecular oxygen (m-dioxyte-trakis(histidinato)dicobalt(II)). The molecular oxygen did not directly react with 2-mercaptoethanol, but,reacted in the form of an adduct with cobalt(II)histidine complex. During the course of the reaction themolecular oxygen is reduced to hydroxide ion while the cobalt(II)histidine complex was oxidized tocobalt(III)histidine while 2-mercaptoethanol is reduced into 2,20-dithiodiethanol. The decrease inabsorbance for the dioxygen complex was monitored spectrophotometrically and was observed that thevalues of rate constant increased with the increase in [2-mercaptoethanol]. The values of kobs also increasedwith increasing [NaOH]. Thus, from the results of these studies, mechanism of the reaction has beenproposed. In addition, the values of various equilibrium constants and rate constants were also determinedusing nonlinear least square techniques.
Chung, I.M.,Siddiqui, N.A.,Kim, S.H.,Nagella, P.,Khan, A.A.,Ali, M.,Ahmad, A. Saudi Pharmaceutical Society 2017 Saudi pharmaceutical journal Vol.25 No.5
Panax ginseng C. A. Meyer (Araliaceae), is a well-known herb and used in the old established system of Oriental remedy, especially in Japan, China and Korea. Four new compounds characterized as (cis)- 7β,11α,19,21-tetra-O-decanoyl-18, 22β-dihydroxy-dammar-1-en-3-one (1), 3β,4α,12β-trihydroxystigmast-5-en-21-yl octadecan-9',12'-dienoate (2), dammar-12, 24-dien-3α, 6β, 15α-triol-3α-D-arabinopyranosyl-6β-L-arabinopyranoside (3) and dammar-24-en-3α, 6β, 16α, 20β-tetraol-3α-D-arabinopyranosyl-6β-D-arabinopyranoside (4) were isolated and established from the ethyl acetate and butanol extracts of the roots of P. ginseng. Their structures were established on the basis of spectral data and chemical reactions. Natural compounds indicative a great reservoir of materials and compounds with evolved biological activity, including antioxidant. Compounds 1-4 were investigated in vitro for antioxidant potential using ferric reducing antioxidant power (FRAP), the Nitric oxide (NO) scavenging activity, reducing power, phosphomolybdenum and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging actions, and the decision showed the compounds 3and 4 have probablyessential antioxidant properties than the compounds 1and 2 presented weak activity.
Oxidative CO_2 reforming of CH4 over Ni/a-Al_2O_3 catalyst
A.S.A. Al-Fatesh,A.A. Ibrahim,A.H. Fakeeha,A.E. Abasaeed,M.R.H. Siddiqui 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.3
Oxidative carbon dioxide reforming of methane to synthesis gas over alumina-supported Ni catalysts was investigated at atmospheric pressure. The reforming reactions were carried out using a CO_2 to CH_4feed ratio of one and reaction temperatures in the range 600–800℃The activity and stability of the catalyst, carbon deposition, and synthesis gas (H_2/CO) ratio were determined. Catalyst deactivation was primarily due to coke formation. energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and thermo-gravimetric/differential analyzer (TG/DTA) techniques were used to confirm carbon deposition. It was observed that increasing the oxygen feed concentration and/or reaction temperatures,enhanced methane conversion and reduced coke formation. When 20% O_2 feed was used at 800℃,catalyst stability test revealed a 99.7% CH_4 conversion, 1.0% CH_4 conversion drop and 1% carbon formation.
EXACT SOLUTION FOR STEADY PAINT FILM FLOW OF A PSEUDO PLASTIC FLUID DOWN A VERTICAL WALL BY GRAVITY
M.K.ALAM,M.T.RAHIM,S.ISLAM,A.M.SIDDIQUI 한국산업응용수학회 2012 Journal of the Korean Society for Industrial and A Vol.16 No.3
Here in this paper, the steady paint film flow on a vertical wall of a non-Newtonian pseudo plastic fluid for drainage problem has been investigated. The exact solution of the non-linear problem is obtained for the velocity profile. Also the average velocity, volume flux, shear stress on the wall, force to hold the wall in position and normal stress difference have been derived. We retrieve Newtonian case, when material constant μ₁ and relaxation time λ₁ equal zero. The results for co-rotational Maxwell fluid is also obtained by taking material constant μ₁ = 0. The effect of the zero shear viscosity η?, the material constant μ₁, the relaxation time λ₁ and gravitational force on the velocity profile for drainage problem are discussed and plotted.
M. A. I. EL-SHAARAWI,S. A. M. SAID,M. U. SIDDIQUI 대한설비공학회 2012 International Journal of Air-Conditioning and Refr Vol.20 No.2
Designing of an intermittently operating solar powered aqua-ammonia absorption system requires determination of design parameters such as operating pressures, operating aqua-ammonia concentrations, energy requirement of all components of the system, etc. These design parameters are mainly dependent on four operating temperatures, namely, the ondenser/day-ambient, the absorber/night-ambient, the evaporator/cooling-load, and the generator temperatures. The present study presents a set of new polynomial form of correlations for directly estimating these design parameters as a function of the four operating temperatures. The developed correlations are simple, easy to use and estimate the design parameters for both, constant pressure and constant temperature absorption intermittent systems with a percentage error of less than 3%.
On a class of modied new Bernstein operators
M. A. Siddiqui,R. R. Agrawal,N. Gupta 장전수학회 2014 Advanced Studies in Contemporary Mathematics Vol.24 No.1
In this paper, by giving a slight modification of the class of new Bernstein type operators introduved in [3], we introduce a class of modified new Bernstein type operators and claim that the midified new Bernstein type operators is more close to classcial Bernstein polynomial in comparison to operators defined in [3]. We prove Voronovskaja type theorem for these operators. We also present a q-analogue of these operators which is an interesting generalizaiton of Bernstein polynomials based on the q-integers, introduved by G M Phillips in [10].
A simplified procedure to incorporate soil non-linearity in missile penetration problems
Siddiqui, N.A.,Kumar, S.,Khan, M.A.,Abbas, H. Techno-Press 2006 Structural Engineering and Mechanics, An Int'l Jou Vol.23 No.3
In this paper, a simplified mathematical procedure is presented to incorporate nonlinearity in soil material to predict the deceleration time history, penetration depth and other relevant parameters for normal impact of missiles into soil targets. Numerical method is employed for these predictions. The results of the study are compared with experimental observations and predictions available in the literature. A good agreement is found with experimental observations and an improvement is observed with existing predictions. A comparison is also made with linear soil model. Some parametric studies are also carried out to obtain the results of practical interest.
Reliability analysis of latticed steel towers against wind induced displacement
M.A. Khan,N.A. Siddiqui,H. Abbas 국제구조공학회 2004 Steel and Composite Structures, An International J Vol.4 No.1
The present study aims at the reliability analysis of steel towers against the limit state of deflection. For this purpose tip deflection of the tower has been obtained after carrying out the dynamic analysis of the tower using modal method. This tip deflection is employed for subsequent reliability analysis. A limit state function based on serviceability criterion of deflection is derived in terms of random variables. A complete procedure of reliability computation is then presented. To study the influence of various random variables on tower reliability, sensitivity analysis has been carried out. Design points, important for probabilistic design of towers, are also located on the failure surface. Some parametric studies have also been included to obtain the results of academic and field interest.