Azhar Mahmood

Phytochemical studies on the seed extract of Piper nigrum Linn.

The petroleum ether extract of dried ground seeds of Piper nigrum Linn. and some column fractions of this extract were subjected to GC and GC-MS analysis, resulting in the identification of fourteen compounds (1–14) by using NIST Mass spectral search program 1998 and the Kovats retention indices. Ten of the compounds (1, 2, 4–12) are reported for the first time from this plant. All the fractions showed insecticidal activity against the fourth instar larvae of Aedes aegypti and against the fourth instar larvae of Anopheles stephensi Liston, determined by the WHO method.

Flavonoid glycosides fromPrunus armeniaca and the antibacterial activity of a crude extract

Investigations on the chemical constituents of the fruits ofPrunus armeniaca have led to the isolation of two new flavonoid glycosides, 4′,5,7-trihydroxy flavone-7-O-[β-D-mannopyranosyl (1″′→2″)]-β-D-allopyranoside (1) and 3,4′,5,7-tetrahydroxy-3′,5′-di-methoxy flavone 3-O-[α-L-rhamnopyranosyl (1″′→6″)]-β-D-galactopyranoside (2), from the butanolic fraction of the fruits. The butanolic extract exhibited antibacterial activity against both Gram positive and Gram negative bacteria. The structures of these compounds were elucidated through spectral studies, including 2D-NMR (COSY, NOESY,J-resolved), HMQC and HMBC experiments.

Structural determination of prunusins A and B, new C-alkylated flavonoids from Prunus domestica, by 1D and 2D NMR spectroscopy

Prunusins A (1) and B (2), the new C‐alkylated flavonoids, have been isolated from the seed kernels of Prunus domestica. Their structures were assigned from 1H and 13C nuclear magnetic resonating spectra, DEPT and by correlation spectroscopy, HMQC and HMBC experiments. 3, 5, 7, 4′‐Tetrahydroxyflavone (3) and 3, 5, 7‐trihydroxy‐8, 4′‐dimethoxyflavone (4) have also been reported from this species. Both compounds (1) and (2) showed significant antifungal activity against pathogenic fungus Trichophyton simmi. Copyright

Purunusides A-C, α-glucosidase inhibitory homoisoflavone glucosides from Prunus domestica

Purunusides A-C (1–3), new homoisoflavone glucosides together with the known compounds β-sitosterol (4) and 6,7-methylenedioxy-8-methoxycoumarin (5) have been isolated from n-butanol and ethyl acetate soluble fractions of Prunus domestica. Their structures were assigned on the basis of spectral studies. The compounds 1–3 showed potent inhibitory activity against the enzyme α-glucosidase.

Real time localization of mobile robotic platform via fusion of Inertial and Visual Navigation System

Inertial Navigation System (INS) is one of the most important component of a mobile robotic platform, be it ground or air based. It is used to localize the mobile robotic platform in the real world and identify its location in terms of latitudes and longitudes or other related coordinate systems. Highly accurate and precise INS is quite expensive and is therefore not suitable for more general purpose applications. It is, therefore, a standard approach in mobile robotics to use a low grade commercial INS coupled with another navigation device to provide a more accurate triangulation. Generally, INS and Global Positioning System (GPS) are integrated using Kalman Filters to provide accurate localization information about the mobile robots. Although, in certain scenarios, the mobile robot is not able to acquire a GPS fix for long durations of time especially when navigating in indoor environments or in areas with inadequate GPS satellite coverage. In such cases, an additional source of location fix is required. This paper describes an accurate and stable data fusion filter which integrates the position of a mobile robot from a Visual Navigation System (VNS) with the position from an INS to accurately localize the robot in absence of GPS data. This research proposes a seven error states model and uses it in Kalman Filter for data fusion. The filter is tuned and tested using dynamic and static data from INS and VNS. Simulation and experimentation results show that the seven error states model based Kalman Filter provides a good balance between accuracy, robustness and processing efficiency for a real time implementation. Experiments also show that in absence of GPS data only a couple of fixes from the VNS are sufficient to quickly correct the position of the mobile robotic platform and three fixes at different times are sufficient for velocity correction of INS.

Local normalized cross correlation for geo-registration

Real time geo-registration is a difficult problem to solve due to issues like partial or complete contrast reversal, partial change in scene and occlusion. In this paper, a local normalized cross correlation based approach is presented that reduces the impact of the above mentioned issues and improves the performance of a geo-registration system. Further enhancements to the proposed approach are also presented to reduce the processing time and improve the performance speed. Extensive experimentation on the proposed approach was conducted to evaluate its performance against standard geo-registration approaches.