Assessing spatiotemporal changes in landcover using geospatial and remote sensing techniques in the Southern fringes of Chennai.

Peri-urban areas are transitional zones on the outer boundaries of cities. These regions have immense growth potential, and it is necessary to observe the land use landcover changes to understand the dynamics of these transformations. The area selected for this study is towards the Southern fringe of Chennai, Tamil Nadu, India, and is analyzed using multi-spectral satellite imagery from Landsat 5 and 8. The primary objective of the study is to assess the change in landcover classes, namely water, land, and vegetation, over a 30-year study period between 1991 and 2021. The peri-urban regions majorly are arable land. Hence, NDVI is considered a suitable index to monitor the landcover changes. The spatiotemporal analysis indicates an increase of 19.43% in land /barren areas towards the Northern parts near the study area and along the transit and industrial corridors. No significant changes are observed in the areas of vegetation that could be attributed to efforts taken to conserve reserve forests and increase green zones in newer developments. A steep depletion of 46.86% of water bodies observed in the region also corresponds to water scarcity problems. Accuracy was assessed using ground-truthing methods, computing the confusion matrix and Kappa coefficient. NDVI is used efficiently in the landcover classification but does not indicate the difference between built-up areas and barren land. Change detection map prepared using ARCGIS indicates the areas that have been converted to other landcover over a period of 30 years. The study reveals an urgent need to bring in policy decisions to conserve waterbodies and green spaces in the initial stages of urban planning for sustainable developments in the fringe areas.

Nano Hydroxyapatite for Biomedical Applications Derived from Chemical and Natural Sources by Simple Precipitation Method.

In the past, bone fractures due to accidents were rectified by surgery and reconstruction of bone structure. In recent times, researchers have been made to find a solution by producing alternate biomaterials. Hydroxyapatite (HAp) is one of the most important bioactive materials used as a substitute for human hard tissue because of its composition being very similar to human bones and teeth. A study has proved that HAp has been used for bone regeneration in clinical trials in the mid-1980. HAp has been used as implant coatings and graft materials and also used as granules, cement, and pastes for bone regenerative applications. HAp coatings on bioimplants improved biocompatibility, bioactivity, and biological fixation. Moreover, some of the deposition methods can be employed to increase the cellular responses of bone regeneration such as sputtering, spraying, electrodeposition, and pulsed layer deposition. The researcher has prepared hydroxyapatite from chemical and natural sources. The surface area and intrinsic properties of the HAp play a vital role in bone-related applications. This can be achieved by synthesizing the HAp from natural sources rather than synthetic materials. The HAp obtained from the chemical source is not fulfilling the requirements of the natural bone. A variety of biowaste materials such as eggshell, crab shell, snail shell, bovine bone, fishbone, and fish scales are available in nature and can be converted to useful calcium source for HAp. The present study is to produce the HAp from biowaste materials like eggshell and chemical sources using the wet precipitation method. The synthesized HAp is coated on the Ti6Al4V alloy using the electrodeposition method, and it is immersed in SBF solution at 37 °C for corrosion testing. The coated samples are investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), electrochemical study, field emission scanning electron icroscopy (FESEM), energy dispersive X-ray analysis (EDAX), AFM, and antibacterial activity with two different microorganisms. FTIR and XRD confirm the functional groups and crystallinity of the HAp. The good antibacterial activity of the HAp is observed against two bacterial strains. The corrosion studies reveal that the HAp derived from a natural source is eco-friendly and nontoxic and has excellent corrosion resistivity and cell adhesion properties. A strong bond is formed between the naturally derived HAp with bone tissue which is involved in the bio-resorption process and does not pose any side effect to the human body compared to synthetically derived HAp. In addition, the biowaste materials are converted to useful biomaterials and can reduce environmental pollution.

Water quality assessment and occurrence of seagrass associated pen shell Pinna bicolor (Gmelin, 1791) and Pinna deltodes (Menke, 1843) in Pudupattinam Coastal Area, Palk Bay, South East Coast, India.

Pen shell species such as Pinna bicolor and Pinna deltodes are found in the muddy region associated with intertidal seagrass in the coastal area of Pudupattinam. The pen shell is one of the sources of animal protein-rich, thereby encouraging the community of pen shells and their study worldwide. The water samples were collected for a year between January to December 2016 and analysed. Salinity (30.1-31.5‰), pH (8.1-8.2), EC value (39.79 103-46.09103 mho), turbidity 25-54 NTU, TSS value (5.51-108 mg/l), DO (4.45-5.74 ml/l), BOD (0.175 -1.05 mg/l), chemical oxygen demand (9.6-39.1 mg/l), chloride 14,276.8-16,124.9 mg/l), sulphate (1975.3-25 mg/l), ammonia (0.022-0.112 µm/l), inorganic phosphate (0.754 µm/l and maximum 1.568 µm/l), total nitrogen (10.829-29.509 µm/l), total phosphate (1.76-3.174 µm/l) and silicate (42.264-64.121 µm/l). Minimum and maximum water temperature ranges (26.9-30.6 °C) were recorded. A total of 623 Pinna bicolor and 1341 Pinna deltodes were collected during the same time and consisted of 305 males and 318 females and 558 males and 783 females, respectively. The improvements in the parameters of physico-chemical and statistical analysis have been shown to have a minor effect on the distribution of these two species in the present research, as environmental factors were not sufficient to influence their distribution.

Crystal structure of 2-benzyl-amino-4-p-tolyl-6,7-di-hydro-5H-cyclo-penta-[b]pyridine-3-carbo-nitrile.

The title compound, C23H21N3, comprises a 2-amino-3-cyano-pyridine ring fused with a cyclo-pentane ring. The later adopts an envelope conformation with the central methyl-ene C atom as the flap. The benzyl and and p-tolyl rings are inclined to one another by 56.18 (15)°, and to the pyridine ring by 81.87 (14) and 47.60 (11)°, respectively. In the crystal, mol-ecules are linked by pairs of N-H⋯Nnitrile hydrogen bonds, forming inversion dimers with an R 2 (2)(12) ring motif. The dimers are linked by C-H⋯π and π-π inter-actions [centroid-centroid distance = 3.7211 (12) Å], forming a three-dimensional framework.

Crystal structure of 1',1''-dimethyl-4'-(4-cholorophen-yl)di-spiro-[11H-indeno[1,2-b]quinoxaline-11,2'-pyrrolidine-3',3''-piperidin]-4''-one.

In the title compound, C30H27ClN4O, the central pyrrolidine ring adopts an envelope conformation with the methyl-ene C atom being the flap. The quinoxaline and indane rings are each essentially planar, with r.m.s. deviations of 0.027 (1) and 0.0417 (1) Å, respectively. The pyrrolidine ring forms dihedral angles of 88.25 (1) and 83.76 (1)° with the quinoxaline and indane rings, respectively. A weak intra-molecular C-H⋯N inter-action is observed. In the crystal, C-H⋯π inter-actions lead to supra-molecular chains along [101] that assemble in the ac plane. Connections along the b axis are of the type Cl⋯Cl [3.6538 (16) Å].

Crystal structure of 2-benzyl-amino-4-(4-bromo-phen-yl)-6,7-di-hydro-5H-cyclo-penta-[b]pyridine-3-carbo-nitrile.

In the title compound C22H18BrN3, the cyclo-pentane ring adopts an envelope conformation with the central methyl-ene C atom as the flap. The dihedral angles between the central pyridine ring and the pendant benzyl and and bromo-benzene rings are 82.65 (1) and 47.23 (1)°, respectively. In the crystal, inversion dimers linked by pairs of N-H⋯Nn (n = nitrile) hydrogen bonds generate R 2 (2)(12) loops. These dimers are linked by weak π-π inter-actions [centroid-centroid distance = 3.7713 (14) Å] into a layered structure.

Crystal structures of 2-benzyl-amino-4-(4-bromo-phen-yl)-6,7,8,9-tetra-hydro-5H-cyclo-hepta-[b]pyridine-3-carbo-nitrile and 2-benzyl-amino-4-(4-chloro-phen-yl)-6,7,8,9-tetra-hydro-5H-cyclo-hepta[b]pyridine-3-carbo-nitrile.

In the title compounds, C24H22BrN3, (I), and C24H22ClN3, (II), the 2-amino-pyridine ring is fused with a cyclo-heptane ring, which adopts a half-chair conformation. The planes of the phenyl and benzene rings are inclined to that of the central pyridine ring [r.m.s. deviations = 0.0083 (1) and 0.0093 (1) Šfor (I) and (II), respectively] by 62.47 (17) and 72.51 (14)°, respectively, in (I), and by 71.44 (9) and 54.90 (8)°, respectively, in (II). The planes of the aromatic rings are inclined to one another by 53.82 (17)° in (I) and by 58.04 (9)° in (II). In the crystals of both (I) and (II), pairs of N-H⋯Nnitrile hydrogen bonds link the mol-ecules, forming inversion dimers with R 2 (2)(12) ring motifs. In (I), the resulting dimers are connected through C-H⋯Br hydrogen bonds, forming sheets parallel to (10-1), and π-π inter-actions [inter-centroid distance = 3.7821 (16) Å] involving inversion-related pyridine rings, forming a three-dimensional network. In (II), the resulting dimers are connected through π-π inter-actions [inter-centroid distance = 3.771 (2) Å] involving inversion-related pyridine rings, forming a two-dimensional network lying parallel to (001).

Crystal structure of 1-benzyl-4-(4-chloro-phen-yl)-2-imino-1,2,5,6,7,8,9,10-octa-hydro-cyclo-octa-[b]pyridine-3-carbo-nitrile.

The title compound, C25H24ClN3, comprises a 2-imino-pyridine ring fused with a cyclo-octane ring, which adopts a twist boat-chair conformation. In the crystal, C-H⋯N inter-actions form R 2 (2)(14) ring motifs and mol-ecules are further connected by weak C-H⋯π inter-actions. The resulting supra-molecular structure is a two-dimensional framework parallel to the ab plane.

Isotypic crystal structures of 1-benzyl-4-(4-bromo-phen-yl)-2-imino-1,2,5,6,7,8,9,10-octa-hydro-cyclo-octa-[b]pyridine-3-carbo-nitrile and 1-benzyl-4-(4-fluoro-phen-yl)-2-imino-1,2,5,6,7,8,9,10-octa-hydro-cyclo-octa-[b]pyridine-3-carbo-nitrile.

The mol-ecules of the two isotypic title compounds, C25H24BrN3, (I), and C25H24FN3, (II), comprise a 2-imino-pyridine ring fused with a cyclo-octane ring. In (I), the cyclo-octane ring adopts a twisted chair-chair conformation, while in (II), this ring adopts a twisted boat-chair conformation. The dihedral angles between the planes of the pyridine ring and the bromo-benzene and phenyl rings are 80.14 (12) and 71.72 (13)°, respectively, in (I). The equivalent angles in (II) are 75.25 (8) and 68.34 (9)°, respectively. In both crystals, inversion dimers linked by pairs of C-H⋯N inter-actions generate R 2 (2)(14) loops, which are further connected by weak C-H⋯π inter-actions, generating (110) sheets.

Crystal structure of 1-benzyl-4-(2,4-di-chloro-phenyl)-2-imino-1,2,5,6,7,8,9,10-octa-hydro-cyclo-octa-[b]pyridine-3-carbo-nitrile.

In the title compound, C25H23Cl2N3, the cyclo-octene ring adopts a twist chair-chair conformation. The dihedral angles between the central pyridine ring (r.m.s. deviation = 0.013 Å) and the pendant chloro-benzene and benzyl rings are 78.07 (11) and 87.47 (12)°, respectively. No directional inter-actions could be identified in the crystal and the packing is governed by van der Waals inter-actions.

Crystal structure of 5-amino-5'-chloro-6-(4-chloro-benzo-yl)-8-nitro-2,3-di-hydro-1H-spiro-[imidazo[1,2-a]pyridine-7,3'-indolin]-2'-one including an unknown solvent mol-ecule.

The asymmetric unit of the title compound, C21H15Cl2N5O4, contains two independent mol-ecules (A and B) having similar conformations. The amine (NH2) group forms an intra-molecular hydrogen bond with the benzoyl group, giving an S(6) ring motif in both mol-ecules. The central six-membered rings adopt sofa conformations and the imidazole rings are planar (r.m.s deviations = 0.0150 and 0.0166 Å). The pyridine and imidazole rings are inclined to one another by 3.54 (1) and 3.03 (1)° in mol-ecules A and B, respectively. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds, forming chains along the a axis which enclose R 2 (2)(16) ring motifs. The rings are linked by weak N-H⋯O and C-H⋯O hydrogen bonds and C-H⋯π inter-actions forming sheets lying parallel to (001). A region of disordered electron density, most probably disordered solvent mol-ecules, occupying voids of ca 753 Å(3) for an electron count of 260, was treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. Their formula mass and unit-cell characteristics were not taken into account during refinement.

5-Amino-5'-bromo-6-(4-methyl-benzo-yl)-8-nitro-2,3-di-hydro-1H-spiro-[imidazo[1,2-a]pyridine-7,3'-indolin]-2'-one including an unknown solvate.

In the title compound, C22H18BrN5O4, the central six-membered ring, derived from 1,4-di-hydro-pyridine, adopts a distorted boat conformation with a puckering amplitude of 0.197 (3) Å, the imidazole ring adopts a twisted conformation with a puckering amplitude of 0.113 (3) Å, and the oxindole moiety is planar with an r.m.s. deviation of 0.0125 Å. Two intra-molecular N-H⋯O hydrogen bonds are formed, each closing an S(6) loop. In the crystal, strong N-H⋯O hydrogen bonds lead to the formation of zigzag chains along the c axis. These are consolidated in the three-dimensional crystal packing by weak N-H⋯O hydrogen bonding, as well as by C-H⋯O, C-H⋯Br and C-H⋯π inter-actions. A small region of electron density well removed from the main mol-ecule was removed with the SQUEEZE procedure in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155] following unsuccessful attempts to model it as a plausible solvent mol-ecule. The unit-cell characteristics do not take into account this feature of the structure.

DENVirDB: a web portal of dengue virus sequence information on Asian isolates.

DENVirDB is a web portal that provides the sequence information and computationally curated information of dengue viral proteins. The advent of genomic technology has increased the sequences available in the public databases. In order to create relevant concise information on Dengue Virus (DENV), the genomic sequences were collected, analysed with the bioinformatics tools and presented as DENVirDB. It provides the comprehensive information of complete genome sequences of dengue virus isolates of Southeast Asia, viz. India, Bangladesh, Sri Lanka, East Timor, Philippines, Malaysia, Papua New Guinea, Brunei and China. DENVirDB also includes the structural and non-structural protein sequences of DENV. It intends to provide the integrated information on the physicochemical properties, topology, secondary structure, domain and structural properties for each protein sequences. It contains over 99 entries in complete genome sequences and 990 entries in protein sequences, respectively. Therefore, DENVirDB could serve as a user friendly database for researchers in acquiring sequences and proteomic information in one platform.

5-Amino-6-benzoyl-8-nitro-2,3-di-hydro-1H-spiro-[imidazo[1,2-a]pyridine-7,3'-indolin]-2'-one dimethyl sulfoxide monosolvate.

In the title compound C21H17N5O4·C2H6OS, the central six-membered ring derived from 1,4-di-hydro-pyridine adopts a distorted boat conformation with a small puckering amplitude of 0.127 (3) Å. The sums of bond angles around the pyridine N atom [358.7 (2)°] and the other imidazolidine N atom [60 (2)°] indicate that these atoms are in sp(2) hybridization, leading to an essentially planar imidazolidine ring. The last heterocycle, an oxindole moiety, is also nearly planar with an r.m.s. deviation of 0.0185 (1) Å. The amine NH2 group forms an intra-molecular hydrogen bond with the benzoyl group, giving a S(6) motif. In the crystal, N-H⋯O hydrogen bonds lead to the formation of chains along the c-axis direction. Within the chains there are further N-H⋯O and C-H⋯O hydrogen bonds enclosing R (2) 2(14) ring motifs. The chains are linked via N-H⋯O and C-H⋯O hydrogen bonds involving the dimethyl sulfoxide solvent mol-ecule which acts as both an acceptor and a donor..

Investigations on the vibrational modes and non-linear optical properties of 4-Fluoro Chalcone crystal.

Organic Nonlinear Optical (NLO) crystals of 4-fluorochalcone (4FC) were synthesized and grown by slow evaporation solution growth method. The grown crystals have been characterised by powder X-ray diffraction, factor group analysis, FTIR, FT-Raman, UV-Vis Spectroscopy, powder SHG and Vickers microhardness tests. Theoretical quantum chemical analysis were performed to determine the first order hyperpolarizability (ß) and HOMO-LUMO analysis of the title compound were computed by GAUSSIAN 03 package.

(3aR*,8bR*)-3a,8b-Dihy-droxy-1-(4-methyl-phen-yl)-2-methyl-sulfanyl-3-nitro-1,8b-di-hydro-indeno-[1,2-b]pyrrol-4(3aH)-one.

The asymmetric unit of the title compound, C19H16N2O5S, contains four independent mol-ecules (A, B, C and D), with two mol-ecules (B and D) displaying disorder in their methyl-sulfanyl groups [occupancy ratios of 0.797 (11):0.203 (11) and 0.85 (2):0.15 (2)]. The nitro groups are twisted slightly out of the planes of the 2-pyrroline rings to which they are bonded with dihedral angles of 10.17 (1), 8.01 (1), 9.44 (1) and 8.87 (1)° in mol-ecules A, B, C and D, respectively. The 2-pyrroline rings are almost orthogonal to the attached tolyl rings, forming dihedral angles of 73.44 (1), 81.21 (1), 88.18 (8) and 73.94 (1)° for mol-ecules A, B, C and D, respectively. A weak intra-molecular O-H⋯O inter-action is observed in mol-ecules B and C. The two hy-droxy groups in each mol-ecule are involved in inter-molecular O-H⋯O hydrogen bonding. In the crystal, mol-ecules are connected via O-H⋯O and C-H⋯O hydrogen bonds, forming a complex three-dimensional network.

10-(4-Chloro-phen-yl)-14a-hy-droxy-12-methyl-8,9,9a,10,12,13,14,14a-octa-hydro-5H-10a,14-methano-indeno-[2',1':4,5]azepino[3,4-b]pyrrolizine-5,15(7H,11H)-dione.

The asymmetric unit of the title compound, C26H25ClN2O3, contains two independent mol-ecules (A and B). The conformation of the two mol-ecules differs essentially in the dihedral angle involving the two benzene rings. They are inclined to one another by 52.47 (10) in A and by 31.75 (11)° in B. In both mol-ecules, the six-membered piperidin-3-one rings have chair conformations. In mol-ecule A, all four five-membered rings have twist conformations. In mol-ecule B, only three of the four five-membered rings have twist conformations. The fourth, of the inden-1-one moiety, has an envelope conformation with the spiro C atom, bonded to the N atom of the pyrrolidine ring, as the flap. A weak intra-molecular O-H⋯N hydrogen bond occurs in each independent mol-ecule while a C-H⋯O inter-action is also observed in mol-ecule A. In the crystal, pairs of O-H⋯O hydrogen bonds link the mol-ecules, forming inversion dimers with graph-set motif R 2 (2)(12). These dimers are further inter-connected by C-H⋯O and C-H⋯π inter-actions, forming a three-dimensional network.

Experimental and theoretical studies of 2,5-dichloroanilinium picrate.

Organic 2,5-dichloroanilinium picrate crystal was grown by using slow evaporation solution technique. The lattice parameter was estimated by powder X-ray diffraction. The absence of absorption at around Nd:YAG fundamental wavelength was confirmed by ultraviolet-visible absorption study. The vibrational analyses confirm the various functional groups present in the grown crystal. The NMR study confirms the presence of chemical environment of hydrogen in the title crystal. The thermogravimetric (TG), differential thermal analysis (DTA) and differential scanning calorimetry (DSC) traces reveals the thermal stability of the compound. The second harmonic generation (SHG) of the crystal was confirmed by Kurtz Perry powder technique. The theoretical studies such as first-order hyperpolarizability (ß), molecular orbitals, electronic excitation and electrostatic potential (ESP) were performed using Gaussian 03W software at HF/6-31G (d) level.

Crystal structure of 2-benzyl-amino-4-(4-meth-oxy-phen-yl)-6,7,8,9-tetra-hydro-5H-cyclo-hepta-[b]pyridine-3-carbo-nitrile.

The title compound, C25H25N3O, comprises a 2-amino-pyridine ring fused with a cyclo-heptane ring, which adopts a chair conformation. The central pyridine ring (r.m.s. deviation = 0.013 Å) carries three substituents, viz. a benzyl-amino group, a meth-oxy-phenyl ring and a carbo-nitrile group. The N atom of the carbo-nitrile group is significantly displaced [by 0.2247 (1) Å] from the plane of the pyridine ring, probably due to steric crowding involving the adjacent substituents. The phenyl and benzene rings are inclined to one another by 58.91 (7)° and to the pyridine ring by 76.68 (7) and 49.80 (6)°, respectively. In the crystal, inversion dimers linked by pairs of N-H⋯Nnitrile hydrogen bonds generate R 2 (2)(14) loops. The dimers are linked by C-H⋯π and slipped parallel π-π inter-actions [centroid-centroid distance = 3.6532 (3) Å] into a three-dimensional structure.

1''-Allyl-5''-(4-meth-oxy-benzyl-idene)-7'-(4-methoxy-phen-yl)-1',3',5',6',7',7a'-hexa-hydro-dispiro-[ace-naphthyl-ene-1,5'-pyrrolo-[1,2-c][1,3]thia-zole-6',3''-piperidine]-2,4''(1H)-dione.

In the title compound, C39H36N2O4S, the piperidine ring adopts a twisted half-chair conformation. In the pyrrolo-thia-zole fused-ring system, the pyrrole ring adopts an envelope conformation (with the C atom bound to the thia-zole ring being the flap atom) and the thia-zole ring also exhibits an envelope conformation (with the N atom bound to the pyrrole ring as the flap). The mol-ecular structure features a weak intra-molecular C-H⋯O inter-action. In the crystal, a C-H⋯O inter-action forms a linear chain along the diagonal of the ac plane, generating a C(14) graph-set motif. A weak C-H⋯π inter-action also occurs.