Showing papers by "P A College of Engineering published in 2006"
TL;DR: In this article, the synthesis, crystal growth and non-linear optical properties of new chalcone derivatives are reported, including 4-propyloxy and 4-butoxy benzaldehydes.
131 citations
TL;DR: The newly synthesized compounds 3m, 3o, 3q showed in vitro anticancer activity and were tested for their antimicrobial activities against Escherichia coli, Staphylococcus aureus, Psuedomonas aeruginosa, Bacillus subtilis and Candida albicans.
106 citations
TL;DR: In this paper, two bis-chalcone derivatives, 1,5-[di(4-methoxyphenyl)]penta-1,4-dien-3-one and 1, 5-[di (4-chlorophenyl]penta]-1, 4-dimethylhexyl hexylhexylhexylon, were synthesized using Z-scan technique using 7ns laser pulses at 532nm.
90 citations
TL;DR: In this paper, the effectiveness of micro jets under the influence of Over, Under, and Correct expansion to control the base pressure in suddenly expanded axi-symmetric ducts was investigated.
Abstract: Purpose – This paper presents an experimental investigation to study the effectiveness of micro jets under the influence of Over, Under, and Correct expansion to control the base pressure in suddenly expanded axi‐symmetric ducts.Design/methodology/approach – Four micro jets of 1 mm orifice diameter located at 90° intervals along a pitch circle diameter of 1.3 times the nozzle exit diameter in the base region was employed as active controls. The tests were conducted for Mach numbers 1.5, 1.3, 1.6, 1.8, 2.0, 2.5, and 3.0. The jets were expanded suddenly into an axi‐symmetric tube with cross‐sectional area 2.56 times that of nozzle exit area. The L/D ratio of the sudden expansion tube was varied from 10 to 1.Findings – From the present studies, it was found that the maximum increase in base pressure is 152 percent for Mach number 2.58. It is found that the micro jets do not adversely influence the wall pressure distribution.Research limitations/implications – As a result of developments in space flights and ...
56 citations
TL;DR: The title compound, C17H15FO3, crystallizes in a centrosymmetric space group and thus does not show any non-linear optical activity and there are two molecules in the asymmetric unit.
Abstract: The title compound, C17H15FO3, crystallizes in a centrosymmetric space group and thus does not show any non-linear optical activity. There are two molecules in the asymmetric unit.
13 citations
TL;DR: The planar molecules of the title compound, C15H13FO2, are normal as discussed by the authors, and the non-centrosymmetric crystal packing may be influenced by weak C−H⋯O and C−F inter-actions.
Abstract: The planar molecules of the title compound, C15H13FO2, are normal. The non-centrosymmetric crystal packing may be influenced by weak C—H⋯O and C—H⋯F interactions.
11 citations
TL;DR: Shan et al. as discussed by the authors confirmed that C19H18O3 has ortho-rhombic symmetry and the only possible inter-molecular interaction is a weak C-H⋯O bond.
Abstract: The title compound, C19H18O3, is confirmed to crystallize with orthorhombic symmetry [Shan et al. (1999). Z. Kristallogr. New Cryst. Struct. 214, 381–382; Marsh (2004). Acta Cryst. B60, 252–253]. The molecule has crystallographically imposed twofold symmetry and the only possible intermolecular interaction is a weak C—H⋯O bond.
9 citations
TL;DR: The geometrical parameters for the title compound, C16H12BrClO2, are normal as mentioned in this paper, and the observed bond lengths and angles imply that there is little electronic conjugation between the two benzene ring systems.
Abstract: The geometrical parameters for the title compound, C16H12BrClO2, are normal. The observed bond lengths and angles imply that there is little electronic conjugation between the two benzene ring systems. An intramolecular C—H⋯Br interaction may help to establish the molecular conformation. The crystal packing results in a centrosymmetric structure.
9 citations
TL;DR: The title compound, C17H12Cl2O, shows significant non-linear optical activity as discussed by the authors, and a twofold rotation axis passes through the carbonyl group. But it cannot be used for optical imaging.
Abstract: The title compound, C17H12Cl2O, shows significant non-linear optical activity. A twofold rotation axis passes through the carbonyl group.
8 citations
TL;DR: The geometrical parameters for the title compound, C16H13ClO2, are normal as discussed by the authors, and packing in a non-centrosymmetric space group, which is consistent with the non-zero second harmonic generation response, may be influenced by a C-H⋯O inter-action.
Abstract: The geometrical parameters for the title compound, C16H13ClO2, are normal. Packing in a non-centrosymmetric space group, which is consistent with the non-zero second harmonic generation response, may be influenced by a C—H⋯O interaction.
6 citations
TL;DR: In this paper, the central C=C double bond is trans configured and the molecule consists of two essentially planar parts which are twisted by 26.89 (5) degrees with respect to each other.
Abstract: In the title biologically active compound, C16H12O3, the central C=C double bond is trans configured. The molecule consists of two essentially planar parts which are twisted by 26.89 (5)degrees with respect to each other.
TL;DR: The title compound, C24H18O2, is a chalcone derivative as discussed by the authors, and the torsion angle between the mean planes of the two naphthalene groups is 54.41 (2)degrees.
Abstract: The title compound, C24H18O2, is a chalcone derivative The torsion angle between the mean planes of the two naphthalene groups is 54.41 (2)degrees.
TL;DR: C22H22O3 as mentioned in this paper is a cyclohexanone derivative with a two-photon absorption and its metrical parameters are similar to those of related C-H-21O3 derivatives.
Abstract: The title compound, C22H22O3, demonstrates a two-photon absorption Its metrical parameters are similar to those of related cyclohexanone derivatives In the crystal structure, two sets of centrosymmetric dimers formed by weak C-H center dot center dot center dot O intermolecular hydrogen bonds combine to form molecular tapes along 101]
TL;DR: The title compound, C9H11N3S2, crystallizes with two molecules in the asymmetric unit, which differ mainly in the degree of planarity as mentioned in this paper, and the C=N double bonds are trans configured.
Abstract: The title compound, C9H11N3S2, crystallizes with two molecules in the asymmetric unit, which differ mainly in the degree of planarity. The C=N double bonds are trans configured. Geometric parameters are in the usual ranges. The crystal structure is characterized by N-H center dot center dot center dot N and N-H center dot center dot center dot S hydrogen bonds.
TL;DR: The title compound, C17H16Br2O2S, crystallizes in a centro-symmetric space group and thus does not show any non-linear optical activity as mentioned in this paper.
Abstract: The title compound, C17H16Br2O2S, crystallizes in a centro-symmetric space group and thus does not show any non-linear optical activity.
TL;DR: In this article, the title compound, C18H14O2S, is shown to have a trans-configurable central C=C double bond and a planar molcule.
Abstract: The molecule of the title compound, C18H14O2S, is essentially planar. The central C=C double bond is trans-configured. Geometric parameters are in normal ranges.
01 Dec 2006
TL;DR: Two defense models for DoS attacks are developed and evaluated: the Secure Overlay Services (SOS) Model and the Server Hopping Model using distributed firewalls, which provide defense in a different part of the network, and has different resource requirements.
Abstract: Denial of Service attacks, orchestrated by a single host or multiple hosts in a coordinated manner, has become an increasingly frequent disturbance in today's Internet. Generally, attackers launch DDoS attacks by directing a massive number of attack sources to send useless traffic to the victim. The victim's services are disrupted when its host or network resources are occupied by the attack traffic. The threat of DDoS attacks has become even more severe as attackers can compromise a huge number of computers using vulnerabilities in popular operating systems [4]. This paper deals with Denial of service (DoS) and Distributed DoS (DDoS) attacks. In the first part, we categorize existing defense mechanisms, and analyze their strengths and weaknesses. In the second part of our investigation, we develop and evaluate two defense models for DoS attacks: the Secure Overlay Services (SOS) Model and the Server Hopping Model using distributed firewalls. Each of these models provide defense in a different part of the network, and has different resource requirements. In the third part of our investigation, we assess the effectiveness of our defense models for different types of DoS attack.
TL;DR: In this paper, the central C=C double bond is trans configured in a biologically active compound, C17H13Cl2FO3, which consists of two essentially planar parts which are twisted by 67.06'2'° with respect to each other.
Abstract: In the title biologically active compound, C17H13Cl2FO3, the central C=C double bond is trans configured. The molecule consists of two essentially planar parts which are twisted by 67.06 (2)° with respect to each other.
TL;DR: In the title compound, C16H14Br2O2, the C-Br bond lengths are significantly different as discussed by the authors, and one of the Br atoms participates in weak hydrogen-bonding inter-actions with C-H groups from adjoining molçecules.
Abstract: In the title compound, C16H14Br2O2, the C—Br bond lengths are dsignificantly different. One of the Br atoms participates in weak hydrogen-bonding interactions with C—H groups from adjoining molecules.
TL;DR: In this article, the indole ring system of C10H8ClNO2 was shown to be planar in the crystal structure and linked by inter-molecular N-H⋯O hydrogen bonds, forming centrosymmetric dimers.
Abstract: In the molecule of the title compound, C10H8ClNO2, the indole ring system is planar. In the crystal structure, the molecules are linked by intermolecular N—H⋯O hydrogen bonds, forming centrosymmetric dimers.
TL;DR: The title compound, C17H15BrOS, crystallizes in a non-centrosymmetric space group and shows significant nonlinear optical activity.
Abstract: The title compound, C17H15BrOS, crystallizes in a non-centrosymmetric space group and shows significant nonlinear optical activity.
TL;DR: In this paper, the central C=C double bond is trans configured and geometric parameters are in the normal ranges, and the C17H17BrO2S is trans-configurable.
Abstract: In the title molecule, C17H17BrO2S, the central C=C double bond is trans configured and geometric parameters are in the normal ranges.
TL;DR: The title compound, C15H12BrNO5S, is a chalcone derivative with potential nonlinear optical properties as mentioned in this paper, which is essentially planar and does not show any unusual geometric parameters.
Abstract: The title compound, C15H12BrNO5S, is a chalcone derivative with potential nonlinear optical (NLO) properties. The molecule is essentially planar and does not show any unusual geometric parameters. The molecular structure and the crystal packing are characterized by C-(HBr)-Br-... and C-(HO)-O-... contacts.
TL;DR: In this article, the title compound was synthesized and characterized by the X-ray diffraction method, and the structure exhibits intermolecular hydrogen bonds of the type C-H-O.
Abstract: The title compound was synthesized and characterized by the X-ray diffraction method. The compound crystallizes in the orthorhombic space group Pcab with cell parameters a = 7.4720(8)A, b = 15.6800(11)A, c = 16.4010(15)A, Z = 8. The structure exhibits intermolecular hydrogen bonds of the type C-H…O.
TL;DR: In this article, the authors present a planar model of the C19H15BrN4OS clique, which is essentially planar, and the geometric parameters are in the usual ranges.
Abstract: Molecules of the title compound, C19H15BrN4OS, are essentially planar. Geometric parameters are in the usual ranges.
TL;DR: In the title compound, C19H13Br2NO4S2, the two bromo-thienyl rings have different orientations with respect to the carbonyl groups as discussed by the authors.
Abstract: In the title compound, C19H13Br2NO4S2, the two bromothienyl rings have different orientations with respect to the carbonyl groups. The nitro group is almost coplanar with the benzene ring to which it is attached.
TL;DR: The geometrical parameters for the title compound, C16H13NO2S, are normal as discussed by the authors, and the non-centrosymmetric crystal packing, which is consistent with the nonzero second harmonic generation response, may be influenced by a weak inter-molecular C-H⋯O inter-action.
Abstract: The geometrical parameters for the title compound, C16H13NO2S, are normal. The non-centrosymmetric crystal packing, which is consistent with the non-zero second harmonic generation response, may be influenced by a weak intermolecular C—H⋯O interaction.
TL;DR: The C17H12BrN3OS compound as discussed by the authors is a planar compound with two intra-molecular C-H⋯N hydrogen bonds, which is essentially planar.
Abstract: The molecule of the title compound, C17H12BrN3OS, is essentially planar. Geometric parameters are in the normal ranges. There are two intramolecular C—H⋯N hydrogen bonds.
TL;DR: The central double bond in the title molcule, C19H19ClO2, is trans configured as discussed by the authors, and the geometric parameters are in normal ranges, and the double bond is trans-configurable.
Abstract: The central double bond in the title molecule, C19H19ClO2, is trans configured. Geometric parameters are in normal ranges.