Sparse and low-rank methods in structural system identification and monitoring

This paper presents sparse and low-rank methods for explicit modeling and harnessing the data structure to address the inverse problems in structural dynamics, identification, and data-driven health monitoring. In particular, it is shown that the structural dynamic features and damage information, intrinsic within the structural vibration response measurement data, possesses sparse and low-rank structure, which can be effectively modeled and processed by emerging mathematical tools such as sparse representation (SR), and low-rank matrix decomposition. It is also discussed that explicitly modeling and harnessing the sparse and low-rank data structure could benefit future work in developing data-driven approaches towards rapid, unsupervised, and effective system identification, damage detection, as well as massive SHM data sensing and management

Structural modifications leading to changes in supramolecular aggregation of thiazolo3, 2-apyrimidines: Insights into their conformational features

The compounds, 7-methyl-3,5-diphenyl-5H-thiazolo3,2-apyrimidine-6-carboxylic acid ethyl ester (1), 3-amino-2-cyano-7-methyl-5-phenyl-5H-thiazolo3,2-apyrimidine-6-carboxylic acid methyl ester (2), 2-dimethylaminomethylene-7-methyl-3-oxo-5-phenyl-2,3-dihydro-5H-thiazolo3,2-apyrimidine-6-carboxylic acid ethyl ester (3), 2-(3-cyano-benzylidene)-5-(4-hydroxy-phenyl)-7-methyl-3-oxo-2,3-dihydro-5H-thiazolo3,2-apyrimidine-6-carboxylic acid methyl ester; with N,N-dimethyl-formamide (4) and 3-ethoxycarbonylmethyl-5-(4-hydroxy-3-methoxy-phenyl)-7-methyl-5H-thiazolo3,2-apyrimidine-6-carboxylic acid methyl ester (5) have been synthesized and their structures evaluated crystallographically. Compound 1 crystallizes in the space group PI with Z=8, with four molecules in the asymmetric unit. Compound 2 also crystallizes in the space group PI with Z=4 wherein asymmetric unit accommodates two molecules. Compound 3 belongs to P21/c with Z=4, compound 4 crystallizes in Pbc2 1 with Z=4 and compound 5 belongs to PI with Z=2. In all the above compounds, the aryl ring positioned at C5 of thiazolopyrimidine ring is almost perpendicular. In the case of compounds with substituted phenyl ring, aryl group-up conformation predominates. However, for compounds with unsubstituted phenyl ring, aryl group-down conformation is adopted. By varying the substituents at positions C2, C3, C6 and on the aryl at C5 in the main molecular scaffold of (1-5), we have observed significant differences in the intermolecular interaction patterns. The packing features of the compounds are controlled by C-H...O, C-H...N, N-H...N O-H...N, C-H...� and �...� weak interactions. © 2014 Indian Academy of Sciences

Synthesis and Crystal Structure Analysis of Ethyl-4-(4-Acetoxy-Phenyl)-3-Acetyl-6-Methyl-2-Thioxo-1,2,3,4-Tetrahydro-Pyrimidine-5-Carboxylate

4-(4-Acetoxy-phenyl)-3-acetyl-6-methyl-2-thioxo-1,2,3,4-tetrahydro-pyrimidine-5-carboxylic acid ethyl ester (2) was synthesized by a two step reaction process. Preliminary spectroscopic analysis was done by IR, 1HNMR and elemental analysis. The crystal and molecular structure was further confirmed using single crystal x-ray diffraction. The dihedral angle between the planes of the aryl and dihydropyrimidine rings is 89.65(6)°, which is almost orthogonal. The dihydropyrimidine ring adopts twist-boat conformation. The crystal structure is stabilized by C-H…O, N-H…S and C-H…π interactions

Methyl 2-(2-bromo­benzyl­idene)-5-(4-hy­droxy­phen­yl)-7-methyl-3-oxo-2,3-dihydro-5H-1,3-thia­zolo[3,2-a]pyrimidine-6-carboxyl­ate

In the title compound, C22H17BrN2O4S, the central dihydropyrimidine ring, with a chiral C atom, is significantly puckered and adopts a half-chair conformation with the chiral C atom displaced from the mean plane of the remaining ring atoms by 0.305 (6) Å. The hydroxy-phenyl ring is positioned axially to the pyrimidine ring and almost bisects it, the dihedral angle between the mean-planes of the two rings being 89.78 (12)°. The meth­oxy­carbonyl group is disordered over two sites with an occupancy ratio of 0.568 (5):0.432 (5), resulting in a major and a minor conformer. In the crystal, O—H⋯N and C—H⋯S inter­actions result in sheets along the c axis. The supra­molecular assembly is stabilized by π–π stacking inter­actions between the 2-bromo­benzyl­idene and thia­zolopyrimidine rings [centroid–centroid distance = 3.632 (1) Å]. In addition, C—H⋯π inter­actions are also observed in the crystal structure

Methyl 5-(4-hy­droxy-3-meth­oxy­phen­yl)-2-(4-meth­oxy­benzyl­idene)-7-methyl-3-oxo-2,3-dihydro-5H-thia­zolo[3,2-a]pyrimidine-6-carboxyl­ate

In the title compound, C24H22N2O6S, a pyrimidine ring substituted with 4-hy­droxy-3-meth­oxy­phenyl is fused with a thia­zole ring. The 4-hy­droxy-3-meth­oxy­phenyl group is positioned axially to the pyrimidine ring, making a dihedral angle 85.36 (7)°. The pyrimidine ring adopts a twist boat conformation. In the crystal, O—H⋯N inter­actions result in a chain running along the b axis. The carbonyl O atom bonded to the thia­zole ring is involved in two C—H⋯O hydrogen-bond inter­actions forming centrosymmetric dimers; the ten- and six-membered rings resulting from these inter­actions have R 2 2(10) and R 1 2(6) motifs, respectively

Structural Modifications Leading to Changes in Supramolecular Aggregation of Thiazolo[3, 2-A]Pyrimidines: Insights into their Conformational Features

The compounds, 7-methyl-3,5-diphenyl-5H-thiazolo[3,2-a]pyrimidine-6-carboxylic acid ethyl ester (1), 3-amino-2-cyano-7-methyl-5-phenyl-5H-thiazolo[3,2-a]pyrimidine-6-carboxylic acid methyl ester (2), 2-dimethylaminomethylene-7-methyl-3-oxo-5-phenyl-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidine- 6-carboxylic acid ethyl ester (3), 2-(3-cyano-benzylidene)-5-(4-hydroxy-phenyl)-7-methyl-3-oxo-2,3- dihydro-5H-thiazolo[3,2-a]pyrimidine-6-carboxylic acid methyl ester; with N,N-dimethyl-formamide (4) and 3-ethoxycarbonylmethyl-5-(4-hydroxy-3-methoxy-phenyl)-7-methyl-5H-thiazolo[3,2-a]pyrimidine-6- carboxylic acid methyl ester (5) have been synthesized and their structures evaluated crystallographically. Compound 1 crystallizes in the space group P¯i with Z=8, with four molecules in the asymmetric unit. Compound 2 also crystallizes in the space group P¯i with Z=4 wherein asymmetric unit accommodates two molecules. Compound 3 belongs to P21/c with Z=4, compound 4 crystallizes in Pbc21 with Z= 4 and compound 5 belongs to P¯i with Z=2. In all the above compounds, the aryl ring positioned at C5 of thiazolopyrimidine ring is almost perpendicular. In the case of compounds with substituted phenyl ring, aryl group-up conformation predominates. However, for compounds with unsubstituted phenyl ring, aryl group-down conformation is adopted. By varying the substituents at positions C2, C3, C6 and on the aryl at C5 in the main molecular scaffold of (1-5), we have observed significant differences in the intermolecular interaction patterns. The packing features of the compounds are controlled by C-H…O, C-H…N, N-H…N O-H…N, C-H…p and p…p weak interactions

Crystal structure of ethyl 5-(3-fluoro-phen-yl)-2-[(4-fluoro-phen-yl)methyl-idene]-7-methyl-3-oxo-2H,3H,5H-[1,3]thia-zolo[3,2-a]pyrimidine-6-carboxyl-ate.

In the title mol-ecule, C23H18F2N2O3S, the pyrimidine ring is in a half-chair conformation and the 3-fluoro-phenyl group is in the axial position. The thia-zole ring (r.m.s. deviation = 0.0252 Å) forms dihedral angles of 84.8 (7) and 9.6 (7)° with the 3-fluoro-substituted and 4-fluoro-substituted benzene rings, respectively. In the crystal, weak C-H⋯F and C-H⋯O hydrogen bonds connect mol-ecules, forming zigzag chains along the b axis. In addition π-π stacking inter-actions with a centroid-centroid distance of 3.7633 (9) Å connect these chains into ladders via inversion-related 4-fluoro-phenyl groups

Methyl 4-(4-hydroxyphenyl)-6-methyl-2-sulfanylidene-1,2,3,4- tetrahydropyrimidine-5-carboxylate

In the title mol­ecule, C13H14N2O3S, the di­hydro­pyrimidine ring is in a flattened sofa conformation, with the methine C atom forming the flap. The dihedral angle between the mean plane of the five essentially planar atoms of the di­hydro­pyrimidine ring [maximum deviation = 0.056 (4) Å] and the benzene ring is 89.4 (2)°. The O atom of the carbonyl group is in a trans conformation with respect to the C=C bond of the di­hydro­pyrimidine ring. In the crystal, N-H...O and O-H...S hydrogen bonds connect mol­ecules, forming a two-dimensional network parallel to (001)

Use of over the counter drugs in urban and rural populations of Mandya district: a cross-sectional study

Background: Over-the-counter (OTC) drugs are medicines which are sold directly to a consumer without a prescription. There is a big potential for misuse and abuse of such products. Over the counter (OTC) drugs are meant for self-medication and are of proved efficacy and safety. Their improper use and unable to follow the precautions due to lack of knowledge of their side effects and interactions could lead to serious complications, especially in children and elderly.Methods: This cross-sectional study was conducted using a pre-tested & semi-structured questionnaire. A total of 400 urban and 400 rural persons were interviewed for this study. 100 persons were interviewed in Mandya city and 50 each from the city in each of the 6 taluks. Data was entered in Microsoft Excel software and was analysed using Statistical Package for Social Sciences (SPSS) software. Chi-square test was used to calculate the difference in use among the urban and rural OTC drug users.Results: A total of 800 persons were interviewed regarding their use of OTC drugs, among them 400 were urban residents and 400 were rural residents of Mandya district. Of the 400 urban persons and rural persons, 310 respondents (77.50%) and 273 respondents (68.25%) reported the use of OTC in the recall period of the last 6 months respectively. The difference in the usage of OTC by urban adults was significantly more than that of rural adults.Conclusions: The proportion of the respondents who had practiced self-medication with OTC drugs is very high. The prevalence of self-medication with OTC drugs in our study was found to be 72.87% and is nearly same in both rural and urban population. As this study was conducted in a limited population in Mandya district, generalization of the study to all the population cannot be done, and it requires large study in all districts of Karnataka with adequate sampling methods