Ramiah Valliappan - Academia.edu (original) (raw)
Papers by Ramiah Valliappan
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Acta Crystallographica Section E Structure Reports Online, 2012
9-(2,4-Difluorophenyl)-3,3,6,6-tetramethyl-3,4,5,6,7,9-hexahydro-2 H -xanthene-1,8-dione
Acta Crystallographica Section E Structure Reports Online, 2014
In the title compound, C23H24F2O3, the central pyran ring has a flat-boat conformation, whereas t... more In the title compound, C23H24F2O3, the central pyran ring has a flat-boat conformation, whereas the two fused cyclohexenone rings adopt envelope conformations, with the C atom bearing the dimethyl substituent being the flap atom in each case. The pyran ring mean plane and the difluorophenyl ring are almost normal to each other, making a dihedral angle of 87.55 (4)°. In the crystal, molecules are linked by pairs of C—H...O hydrogen bonds, forming inversion dimers with anR22(8) ring motif. The F atom at position 2 on the difluorophenyl ring is disordered over the 2- and 6-positions, and has a refined occupancy ratio of 0.932 (3):0.068 (3).
Proceedings of the International Conference on Chemical,Material and Food Engineering, 2015
In order to improve the adsorption performance of Attapulgite (ATP) on dyes. ATP was modified by ... more In order to improve the adsorption performance of Attapulgite (ATP) on dyes. ATP was modified by cetyl trimethyl ammonium bromide (CTAB), and the ATP before and after modified were characterized with XRD and FT-IR. The results showed that ATP had been modified with CTAB successfully, and crystal structure of ATP was unchanged. The influence factors such as modified agent dosage, solution temperature, pH value of solution and dyes structure on adsorption properties of ATP were discussed. The results suggested that the optimal dosage of modifier was 10 wt% based on the quality of ATP. ATP had good adsorption effect on methyl orange when the pH value was pH value was in the rage of 3.6 to 11.6, temperature was in the range of 30-50 o C. The order of adsorption effect was as follow: methyl orange>methylene blue>amido black>methyl blue>congo red>rhodamine B.
E-Journal of Chemistry, 2010
The dye, Grey BL was adsorbed on an adsorbent prepared from mature leaves of the Pungan tree (Pon... more The dye, Grey BL was adsorbed on an adsorbent prepared from mature leaves of the Pungan tree (Pongamia glabra). A batch adsorption study was carried out with variable adsorbate concentration, adsorbent amount and pH. Ninety three percent of the dye could be removed by 2 g of the derris leaf powder from 1 L of an aqueous solution containing 25 mg of the dye at 300 K. The adsorption followed pseudo first order kinetics with a mean rate constant of 3.73 ×10-3min-1and an intraparticle diffusion rate constant of 6.36 x10-2mg g-1min-0.5. A possible mechanism of adsorption was suggested on the basis of concurrently operating surface adsorption and pore diffusion. The experimental data yielded excellent fits with Langmuir and Freundlich isotherm equations. The Langmuir monolayer capacity had a mean value of 8.27 mg g-1. The results indicated that the dye, Grey BL, strongly interacts with a biomass-based adsorbent, the Derris (Pongamia glabra) leaf powder.
TENCON 2007 - 2007 IEEE Region 10 Conference, 2007
ABSTRACT The objective of this paper is to develop a prototype called intelligent mammography ret... more ABSTRACT The objective of this paper is to develop a prototype called intelligent mammography retrieval engine. It can be implemented as a computer software that able to examine/analyst digital mammogram image and automatically yield its finding and recommendation. The computerized examination is done through comparison of a new digital mammogram image with the existing collection of digital mammogram image in the database. The digital mammogram images in the database that exactly identical to the new digital mammogram image will be sources of yielding finding and recommendation of new digital mammogram image.
Synlett, 2003
A general and practical chemistry route to the synthesis of polyfunctionlized benzopyrans using t... more A general and practical chemistry route to the synthesis of polyfunctionlized benzopyrans using tetrabutylammonium bromide (TBABr) as the catalyst (10 mol%) is described. This method provides several advantages such as neutral conditions, high yields and simple work-up procedure. In addition, water was chosen as a green solvent.
Research on Chemical Intermediates, 2013
ABSTRACT An efficient one-pot, atom-economical, three-component reaction of aromatic aldehydes, d... more ABSTRACT An efficient one-pot, atom-economical, three-component reaction of aromatic aldehydes, dimedone, and malononitrile was developed, for the first time, using SiO2-OK as an efficient solid base reusable catalyst, producing various substituted 2-amino-4H-benzo[b]pyran derivatives in good to excellent yields, under solvent-free conditions at 80 °C. This synthesis was confirmed to follow the group–assistant–purification chemistry process, which can avoid traditional chromatography and recrystallization purifications. The catalyst is inexpensive and easily obtained, stable and storable, and easily recycled, being reused at least six times without any marked change in its catalytic activity.
Research on Chemical Intermediates, 2013
Abstract A series of novel spiroindanedionepyrrolizidines have been synthesized by multicomponent... more Abstract A series of novel spiroindanedionepyrrolizidines have been synthesized by multicomponent 1, 3-dipolar cycloaddition of a variety of (E)-3-aryl-1-(thiophen-2-yl) prop-2-en-1-ones with unstabilized azomethine ylides generated from ninhydrin and l-proline. ...
Medicinal Chemistry Research, 2007
A series of new 3,5-diaryl-N-hydroxymethylene-1,4-thiazine-1,1-dioxides and 3,5-diaryl-N-methoxym... more A series of new 3,5-diaryl-N-hydroxymethylene-1,4-thiazine-1,1-dioxides and 3,5-diaryl-N-methoxymethylene-tetrahydro-1,4-thiazines-1,1-dioxides were synthesized and their antimicrobial activities were tested against Gram-positive (Bacillus subtilis, Streptococci) and Gram-negative bacteria (Escherichia coli and Klebsiella penumoniae) and against the fungi Penicillium inclobium and Aspergillus flavus. The synthesized compounds have been characterized on the basis of elemental analyses, infrared spectroscopy (IR), and nuclear magnetic resonance (NMR).
sphinxsai.com
Gallstone disease is common in developing as well as developed countries. The exact mechanism of ... more Gallstone disease is common in developing as well as developed countries. The exact mechanism of stone formation is not yet understood clearly. An attempt has been made to clarify such problem. This is a case-control study with gallstone disease in Cuddalore district of Tamilnadu, the study population consists of 124 cases and 50 controls residing in the same region. Data were collected through standard questionnaire during the period between May 2007 and June 2009 (25 months) and the results were compiled and interpreted. The investigation suggests that mixed stones are predominant in the selected study area. The significant associations (BMI, beverage consumption, pregnancy, socioeconomic status, and food habit) between control and patients groups were found.
Romanian Journal of …, 2009
The objective of this study was to measure the alterations in serum elements, viz., copper (Cu), ... more The objective of this study was to measure the alterations in serum elements, viz., copper (Cu), iron (Fe), selenium (Se) and zinc (Zn) in patients (n = 39) with chronic hepatitis B and to compare them with the results of healthy volunteers (n = 24) by using ICP-AES. Significant low serum levels of Se, Zn and high level of serum Cu were observed in patients with hepatitis B virus, as compared with normal healthy controls. Serum Fe concentrations did not show alterations in hepatitis B patients compared with healthy individuals. The study showed that Cu, Fe, Se and Zn concentrations in serum of hepatitis B patients were 1.499 ± 0.297 ppm, 1.211 ± 0.206 ppm, 0.042 ± 0.014 ppm and 0.550 ± 0.094 ppm respectively. In healthy individuals these concentrations were 1.003 ± 0.159 ppm, 1.272 ± 0.340 ppm, 0.059 ± 0.008 ppm, 0.883 ± 0.070 ppm respectively. The results were statistically compared (p < 0.05) with those of healthy individuals. The degrees of involvement of trace elements due to hepatitis B virus in human blood serum were discussed. This study supports the association of trace elements such as Se, Cu and Zn with hepatitis B.
The paper describes a convenient method for the preparation of 4-substituted phenyl-5-[1-(4-fluor... more The paper describes a convenient method for the preparation of 4-substituted phenyl-5-[1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-yl]-2H-1,2,4-triazole-3-thiones. The structures of the synthesized compounds are established by the results of LCMS, 1 H NMR, 13 C NMR, and IR and elemental analyses. The mercaptotriazoles are indicated to be in thione form by 1 H NMR spectra. All the synthesized compounds have been screened for antibacterial and antifungal activities. Compounds 12d and 12h exhibit encouraging results, while the remaining compounds show moderate activities. On the basis of spectral studies, formation of 2amino-1,3,4-thiadiazoles from the isobenzofuran acyl thiosemicarbazides 11(a-h) is ruled out.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Acta Crystallographica Section E Structure Reports Online, 2012
9-(2,4-Difluorophenyl)-3,3,6,6-tetramethyl-3,4,5,6,7,9-hexahydro-2 H -xanthene-1,8-dione
Acta Crystallographica Section E Structure Reports Online, 2014
In the title compound, C23H24F2O3, the central pyran ring has a flat-boat conformation, whereas t... more In the title compound, C23H24F2O3, the central pyran ring has a flat-boat conformation, whereas the two fused cyclohexenone rings adopt envelope conformations, with the C atom bearing the dimethyl substituent being the flap atom in each case. The pyran ring mean plane and the difluorophenyl ring are almost normal to each other, making a dihedral angle of 87.55 (4)°. In the crystal, molecules are linked by pairs of C—H...O hydrogen bonds, forming inversion dimers with anR22(8) ring motif. The F atom at position 2 on the difluorophenyl ring is disordered over the 2- and 6-positions, and has a refined occupancy ratio of 0.932 (3):0.068 (3).
Proceedings of the International Conference on Chemical,Material and Food Engineering, 2015
In order to improve the adsorption performance of Attapulgite (ATP) on dyes. ATP was modified by ... more In order to improve the adsorption performance of Attapulgite (ATP) on dyes. ATP was modified by cetyl trimethyl ammonium bromide (CTAB), and the ATP before and after modified were characterized with XRD and FT-IR. The results showed that ATP had been modified with CTAB successfully, and crystal structure of ATP was unchanged. The influence factors such as modified agent dosage, solution temperature, pH value of solution and dyes structure on adsorption properties of ATP were discussed. The results suggested that the optimal dosage of modifier was 10 wt% based on the quality of ATP. ATP had good adsorption effect on methyl orange when the pH value was pH value was in the rage of 3.6 to 11.6, temperature was in the range of 30-50 o C. The order of adsorption effect was as follow: methyl orange>methylene blue>amido black>methyl blue>congo red>rhodamine B.
E-Journal of Chemistry, 2010
The dye, Grey BL was adsorbed on an adsorbent prepared from mature leaves of the Pungan tree (Pon... more The dye, Grey BL was adsorbed on an adsorbent prepared from mature leaves of the Pungan tree (Pongamia glabra). A batch adsorption study was carried out with variable adsorbate concentration, adsorbent amount and pH. Ninety three percent of the dye could be removed by 2 g of the derris leaf powder from 1 L of an aqueous solution containing 25 mg of the dye at 300 K. The adsorption followed pseudo first order kinetics with a mean rate constant of 3.73 ×10-3min-1and an intraparticle diffusion rate constant of 6.36 x10-2mg g-1min-0.5. A possible mechanism of adsorption was suggested on the basis of concurrently operating surface adsorption and pore diffusion. The experimental data yielded excellent fits with Langmuir and Freundlich isotherm equations. The Langmuir monolayer capacity had a mean value of 8.27 mg g-1. The results indicated that the dye, Grey BL, strongly interacts with a biomass-based adsorbent, the Derris (Pongamia glabra) leaf powder.
TENCON 2007 - 2007 IEEE Region 10 Conference, 2007
ABSTRACT The objective of this paper is to develop a prototype called intelligent mammography ret... more ABSTRACT The objective of this paper is to develop a prototype called intelligent mammography retrieval engine. It can be implemented as a computer software that able to examine/analyst digital mammogram image and automatically yield its finding and recommendation. The computerized examination is done through comparison of a new digital mammogram image with the existing collection of digital mammogram image in the database. The digital mammogram images in the database that exactly identical to the new digital mammogram image will be sources of yielding finding and recommendation of new digital mammogram image.
Synlett, 2003
A general and practical chemistry route to the synthesis of polyfunctionlized benzopyrans using t... more A general and practical chemistry route to the synthesis of polyfunctionlized benzopyrans using tetrabutylammonium bromide (TBABr) as the catalyst (10 mol%) is described. This method provides several advantages such as neutral conditions, high yields and simple work-up procedure. In addition, water was chosen as a green solvent.
Research on Chemical Intermediates, 2013
ABSTRACT An efficient one-pot, atom-economical, three-component reaction of aromatic aldehydes, d... more ABSTRACT An efficient one-pot, atom-economical, three-component reaction of aromatic aldehydes, dimedone, and malononitrile was developed, for the first time, using SiO2-OK as an efficient solid base reusable catalyst, producing various substituted 2-amino-4H-benzo[b]pyran derivatives in good to excellent yields, under solvent-free conditions at 80 °C. This synthesis was confirmed to follow the group–assistant–purification chemistry process, which can avoid traditional chromatography and recrystallization purifications. The catalyst is inexpensive and easily obtained, stable and storable, and easily recycled, being reused at least six times without any marked change in its catalytic activity.
Research on Chemical Intermediates, 2013
Abstract A series of novel spiroindanedionepyrrolizidines have been synthesized by multicomponent... more Abstract A series of novel spiroindanedionepyrrolizidines have been synthesized by multicomponent 1, 3-dipolar cycloaddition of a variety of (E)-3-aryl-1-(thiophen-2-yl) prop-2-en-1-ones with unstabilized azomethine ylides generated from ninhydrin and l-proline. ...
Medicinal Chemistry Research, 2007
A series of new 3,5-diaryl-N-hydroxymethylene-1,4-thiazine-1,1-dioxides and 3,5-diaryl-N-methoxym... more A series of new 3,5-diaryl-N-hydroxymethylene-1,4-thiazine-1,1-dioxides and 3,5-diaryl-N-methoxymethylene-tetrahydro-1,4-thiazines-1,1-dioxides were synthesized and their antimicrobial activities were tested against Gram-positive (Bacillus subtilis, Streptococci) and Gram-negative bacteria (Escherichia coli and Klebsiella penumoniae) and against the fungi Penicillium inclobium and Aspergillus flavus. The synthesized compounds have been characterized on the basis of elemental analyses, infrared spectroscopy (IR), and nuclear magnetic resonance (NMR).
sphinxsai.com
Gallstone disease is common in developing as well as developed countries. The exact mechanism of ... more Gallstone disease is common in developing as well as developed countries. The exact mechanism of stone formation is not yet understood clearly. An attempt has been made to clarify such problem. This is a case-control study with gallstone disease in Cuddalore district of Tamilnadu, the study population consists of 124 cases and 50 controls residing in the same region. Data were collected through standard questionnaire during the period between May 2007 and June 2009 (25 months) and the results were compiled and interpreted. The investigation suggests that mixed stones are predominant in the selected study area. The significant associations (BMI, beverage consumption, pregnancy, socioeconomic status, and food habit) between control and patients groups were found.
Romanian Journal of …, 2009
The objective of this study was to measure the alterations in serum elements, viz., copper (Cu), ... more The objective of this study was to measure the alterations in serum elements, viz., copper (Cu), iron (Fe), selenium (Se) and zinc (Zn) in patients (n = 39) with chronic hepatitis B and to compare them with the results of healthy volunteers (n = 24) by using ICP-AES. Significant low serum levels of Se, Zn and high level of serum Cu were observed in patients with hepatitis B virus, as compared with normal healthy controls. Serum Fe concentrations did not show alterations in hepatitis B patients compared with healthy individuals. The study showed that Cu, Fe, Se and Zn concentrations in serum of hepatitis B patients were 1.499 ± 0.297 ppm, 1.211 ± 0.206 ppm, 0.042 ± 0.014 ppm and 0.550 ± 0.094 ppm respectively. In healthy individuals these concentrations were 1.003 ± 0.159 ppm, 1.272 ± 0.340 ppm, 0.059 ± 0.008 ppm, 0.883 ± 0.070 ppm respectively. The results were statistically compared (p < 0.05) with those of healthy individuals. The degrees of involvement of trace elements due to hepatitis B virus in human blood serum were discussed. This study supports the association of trace elements such as Se, Cu and Zn with hepatitis B.
The paper describes a convenient method for the preparation of 4-substituted phenyl-5-[1-(4-fluor... more The paper describes a convenient method for the preparation of 4-substituted phenyl-5-[1-(4-fluorophenyl)-1,3-dihydroisobenzofuran-5-yl]-2H-1,2,4-triazole-3-thiones. The structures of the synthesized compounds are established by the results of LCMS, 1 H NMR, 13 C NMR, and IR and elemental analyses. The mercaptotriazoles are indicated to be in thione form by 1 H NMR spectra. All the synthesized compounds have been screened for antibacterial and antifungal activities. Compounds 12d and 12h exhibit encouraging results, while the remaining compounds show moderate activities. On the basis of spectral studies, formation of 2amino-1,3,4-thiadiazoles from the isobenzofuran acyl thiosemicarbazides 11(a-h) is ruled out.