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1.
Ecol Indic ; 111: 106020, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32372880

RESUMO

Ecological perturbations caused by biotic invasion have been identified as a growing threat to global sustainability. Invasive alien plants species (IAPS) are considered to be one of the major drivers of biodiversity loss and thereby altering the ecosystem services and socio-economic conditions through different mechanisms. Although the ecological impacts of IAPS are well documented, there is a dearth of studies regarding their economic quantification, livelihood considerations, biotechnological prospects (phytoremediation, bioenergy, phyto-synthesis of nanoparticles, biomedical, industrial applications etc.) and human health risk assessments of IAPS. In this context, the current panoramic review aimed to investigate the environmental, socio-ecological and health risks posed by IAPS as well as the compounded impact of IAPS with habitat fragmentation, climate and land use changes. To this end, the need of an integrated trans-disciplinary research is emphasized for the sustainable management of IAPS. The management prospects can be further strengthened through their linkage with geo-spatial technologies (remote sensing and GIS) by mapping and monitoring the IAPS spread. Further, the horizon of IAPS management is expanded to ecological indicator perspectives of IAPS, biosecurity, and risk assessment protocols with critical discussion. Moreover, positive as well as negative implications of the IAPS on environment, health, ecosystem services and socio-economy (livelihood) are listed so that a judicious policy framework could be developed for the IAPS management in order to mitigate the human health implications.

2.
Polym Bull (Berl) ; 80(3): 3055-3083, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-35378874

RESUMO

The density functional theory calculation has been carried out for the analysis of 5-chlorouracil using DFT/Gaussian 09 with GAR2PED. Recorded experimental spectra for Raman and IR of 5-chlorouracil have been analyzed all fundamental vibrational modes using the outcome results of DFT at 6-311++G** of Gaussian 09 calculations and the GaussView 5.09. To help the analysis of vibrational modes, GAR2PED program has been used in the calculation of PEDs. The charge transfer properties of 5-chlorouracil have been analyzed using HOMO and LUMO level energy analysis. HOMO and LUMO energy gap study supports the charge transfer possibility in molecule. These have been made to study for reactivity and stability of heterocyclic molecules for the analysis of antiviral drugs against the new corona virus: COVID-19. Here, the smaller energy gap of 5-chlorouracil is more responsible for charge transfer interaction in the heterocyclic drug molecules and a reason of more bioactivity. The electron density mapping within molecular electrostatic potential plot and electrostatic potential plotting within iso-surface plot have been evaluated the charge distribution concept in the molecule as the nucleophilic reactions and electrophilic sites. These computations have been used to produce the molecular charges, structure and thermodynamic functions of biomolecule. This study has been made to all internal modes of chloro group substituent at pyrimidine ring of C5 atom. The splitting of frequencies has arisen in the two species for the normal distribution modes.

3.
Front Plant Sci ; 14: 1181293, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38333040

RESUMO

Abiotic and biotic factors have considerable impact on the plasticity of plant functional traits, which influences forest structure and productivity; however, their inter-relationships have not been quantified for fragmented tropical dry forest (TDF) ecosystems. We asked the following questions: (1) what are the variations in the plasticity of functional traits due to soil moisture availability in TDF fragments? (2) what are the roles of soil nutrients and forest disturbances in influencing variations in the plasticity of functional traits in the TDF fragments? and (3) how do the variations in the plasticity of functional traits influence the structure and productivity of TDF fragments? Based on linear mixed-effects results, we observed significant variations among tree species for soil moisture content (SMC) under the canopy and selected functional traits across forest fragments. We categorized tree species across fragments by principal component analysis (PCA) and hierarchical clustering on principal components (HCPC) analyses into three functional types, viz., low wood density high deciduous (LWHD), high wood density medium deciduous (HWMD), and high wood density low deciduous (HWLD). Assemblage of functional traits suggested that the LWHD functional type exhibits a drought-avoiding strategy, whereas HWMD and HWLD adopt a drought-tolerant strategy. Our study showed that the variations in functional trait plasticity and the structural attributes of trees in the three functional types exhibit contrasting affinity with SMC, soil nutrients, and disturbances, although the LWHD functional type was comparatively more influenced by soil resources and disturbances compared to HWMD and HWLD along the declining SMC and edge distance gradients. Plasticity in functional traits for the LWHD functional type exhibited greater variations in traits associated with the conservation of water and resources, whereas for HWMD and HWLD, the traits exhibiting greater plasticity were linked with higher productivity and water transport. The cumulative influence of SMC, disturbances, and functional trait variations was also visible in the relative abundance of functional types in large and small sized fragments. Our analysis further revealed the critical differences in the responses of functional trait plasticity of the coexisting tree species in TDF, which suggests that important deciduous endemic species with drought-avoiding strategies might be prone to strategic exclusion under expected rises in anthropogenic disturbances, habitat fragmentation, and resource limitations.

4.
ScientificWorldJournal ; 2012: 790219, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22448139

RESUMO

Accurate characterization of biomass in different forest components is important to estimate their contribution to total carbon stock. Due to lack of allometric equations for biomass estimation of woody species at juvenile stage, the carbon stored in this forest component is ignored. We harvested 47 woody species at juvenile stage in a dry tropical forest and developed regression models for the estimation of above-ground biomass (AGB). The models including wood-specific gravity (ρ) exhibited higher R(2) than those without ρ. The model consisting of ρ, stem diameter (D), and height (H) not only exhibited the highest R(2) value but also had the lowest standard error of estimate. We suggest that ρ-based regression model is a viable option for nondestructive estimation of biomass of forest trees at juvenile stage.


Assuntos
Biomassa , Clima Tropical , Madeira
5.
Sci Total Environ ; 738: 139710, 2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-32544704

RESUMO

This paper reviews dissimilatory nitrate reduction to ammonium (DNRA) in soils - a newly appreciated pathway of nitrogen (N) cycling in the terrestrial ecosystems. The reduction of NO3- occurs in two steps; in the first step, NO3- is reduced to NO2-; and in the second, unlike denitrification, NO2- is reduced to NH4+ without intermediates. There are two sets of NO3-/NO2- reductase enzymes, i.e., Nap/Nrf and Nar/Nir; the former occurs on the periplasmic-membrane and energy conservation is respiratory via electron-transport-chain, whereas the latter is cytoplasmic and energy conservation is both respiratory and fermentative (Nir, substrate-phosphorylation). Since, Nir catalyzes both assimilatory- and dissimilatory-nitrate reduction, the nrfA gene, which transcribes the NrfA protein, is treated as a molecular-marker of DNRA; and a high nrfA/nosZ (N2O-reductase) ratio favours DNRA. Recently, several crystal structures of NrfA have been presumed to producee N2O as a byproduct of DNRA via the NO (nitric-oxide) pathway. Meta-analyses of about 200 publications have revealed that DNRA is regulated by oxidation state of soils and sediments, carbon (C)/N and NO2-/NO3- ratio, and concentrations of ferrous iron (Fe2+) and sulfide (S2-). Under low-redox conditions, a high C/NO3- ratio selects for DNRA while a low ratio selects for denitrification. When the proportion of both C and NO3- are equal, the NO2-/NO3- ratio modulates partitioning of NO3-, and a high NO2-/NO3- ratio favours DNRA. A high S2-/NO3- ratio also promotes DNRA in coastal-ecosystems and saline sediments. Soil pH, temperature, and fine soil particles are other factors known to influence DNRA. Since, DNRA reduces NO3- to NH4+, it is essential for protecting NO3- from leaching and gaseous (N2O) losses and enriches soils with readily available NH4+-N to primary producers and heterotrophic microorganisms. Therefore, DNRA may be treated as a tool to reduce ground-water NO3- pollution, enhance soil health and improve environmental quality.


Assuntos
Compostos de Amônio , Ecossistema , Nitrogênio , Desnitrificação , Nitratos
6.
Environ Res ; 109(3): 258-66, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19147131

RESUMO

The goal of our research was to assess the impact of post-mining land subsidence, caused due to underground coal mining operations, on fine root biomass and root tips count; plant available nutrient status, microbial biomass N (MBN) and N-mineralization rates of a Southern tropical dry deciduous forest of Singareni Coalfields of India. The changes were quantified in all the three (rainy, winter and summer) seasons, in slope and depression microsites of the subsided land and an adjacent undamaged forest microsite. Physico-chemical characteristics were found to be altered after subsidence, showing a positive impact of subsidence on soil moisture, bulk density, water holding capacity, organic carbon content, total N and total P. The increase in all the parameters was found in depression microsites, while in slope microsites, the values were lower. Fine root biomass and root tips count increased in the subsided depression microsites, as demonstrated by increases of 62% and 45%, respectively. Soil nitrate-N and phosphate-P concentrations were also found to be higher in depression microsite, showing an increase of 35.68% and 24.74%, respectively. Depression microsite has also shown the higher MBN value with an increase over control. Net nitrification, net N-mineralization and MBN were increased in depression microsite by 29.77%, 25.72% and 34%, respectively. There was a positive relation of microbial N with organic C, fine root biomass and root tips.


Assuntos
Minas de Carvão , Nitrogênio/análise , Solo/análise , Árvores/crescimento & desenvolvimento , Clima Tropical , Biomassa , Índia , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Solo/normas , Árvores/metabolismo , Árvores/microbiologia
7.
Heliyon ; 5(12): e02955, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31872124

RESUMO

Vibrational spectra (Infra Red and Raman) of uracil and 5-aminouracil have been recorded as well as reproduced in solid phase for the pyrimidinal region (200-2000 cm-1) and the internal modes were analyzed especially for pyrimidine ring of bio-molecules theoretically by using the density functional theory (DFT) calculations on the different basis sets for Restricted Hartree-Fock (RHF) by employing the Gaussian-03 program. These quantum chemical calculations have been employed to yield the Mulliken atomic charges, atomic polarizability tensor (APT) charges and thermodynamic functional properties of these bio-molecules. These DFT calculations have been computed for the some important internal ring modes especially to pyrimidine ring of uracil with a substituent amino-group (NH2) at site of C5 atom on pyrimidine ring.

8.
Microbiol Res ; 162(3): 276-83, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-16875809

RESUMO

Population dynamics of methane-oxidizing bacteria (MOB) was measured for 2 consecutive years for four forest and one savanna sites in seasonally dry tropical regions of India. The soils were nutrient-poor and well drained. These sites differed in vegetational cover and physico-chemical features of soils. There were significant differences in MOB population size during the 2 years (mean 0.40 and 0.48 x 10(5) cells g(-1) dry soil), and at different sites (mean 0.38-0.59 x 10(5) cells g(-1) dry soil). The mean population size of MOB was higher (P<0.05) in dry seasons than in the rainy season at all the sites. There was a significant season and site interaction, indicating that the effect of different seasons differed across the sites. There was a positive relation between soil moisture and MOB population size during summer (the driest period) and a negative relation during the rest of the year. The number of MOB was consistently higher for the Kotwa hill base site than rest of the sites having higher soil organic C and total N. The results suggested that in seasonally dry tropical forests the moisture, C and N status of the soil regulates the population size of MOB (methanotrophs) in the long term.


Assuntos
Carbono/análise , Metano/metabolismo , Nitrogênio/metabolismo , Microbiologia do Solo , Solo/análise , Euryarchaeota/crescimento & desenvolvimento , Euryarchaeota/metabolismo , Umidade , Nitrogênio/análise , Estações do Ano , Árvores , Clima Tropical
9.
Microbiol Res ; 161(2): 169-79, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16427522

RESUMO

The study was conducted in Vindhyan region, to assess the N-mineralization, nitrification and size of viable community of ammonium- and nitrite-oxidizing bacteria as affected by different sites and seasons. Six different ecosystems (four forests and two savannas), which differ in terms of topography, vegetation and moisture status, were selected for the present study. The soils of the study sites differ significantly in its physico-chemical properties. The savanna site had significantly higher pH (7.2), bulk density (1.37 g cm(-3)) and silt content (67.80%) but lower water holding capacity (1.37%), total-C (16,356 microg g(-1) dry soil), N (1090 microg g(-1) dry soil) and P (213 microg g(-1) dry soil) than forest sites. The soil moisture content, N-mineralization, nitrification rates and numbers of ammonium- and nitrite-oxidizing bacteria were highest in the wet season and lowest in dry season, while the size of mineral-N (NH4(+)-N and NO3(-)-N) showed a reverse trend at the sites. The N-mineralization, nitrification and nitrifier population size differ significantly across the site and season. The numbers of free-living cells of ammonium- and nitrite-oxidizing bacteria were significantly related to each other and to N-mineralization, nitrification, soil moisture and mineral-N components. The N-mineralization, nitrification and the viable number of nitrifying cells were consistently higher for forest soils compared to savanna sites. It was concluded that soil microbial process (N-mineralization and nitrification) and nitrifier population size were dependent on site topography, vegetation cover and soil moisture status.


Assuntos
Bradyrhizobiaceae/metabolismo , Nitrogênio/metabolismo , Microbiologia do Solo , Solo/análise , Nitrogênio/análise , Análise de Regressão , Estações do Ano , Árvores , Clima Tropical
10.
Cancer Res ; 61(10): 4197-205, 2001 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-11358845

RESUMO

Genetic defects in the Wnt-1 signaling pathway contribute to human tumor progression and are especially prevalent in colorectal cancer. We screened mouse C57MG cells to isolate mRNAs induced by Wnt-1 and identified Stra6, an mRNA known to be up-regulated by retinoic acid. Up-regulation of Stra6 mRNA was also observed in hyperplastic mammary tissue and mammary gland tumors from transgenic mice expressing Wnt-1 and in human tumors that frequently harbor defects in Wnt-1 signaling. Stimulation of C57MG cells with retinoic acid plus Wnt-1 resulted in expression of Stra6 transcript to levels greatly exceeding that observed with either stimulus alone. This synergy could be explained in part by the up-regulation of retinoic acid receptor-gamma that was observed in response to Wnt-1 signaling. Accordingly, treatment of human colorectal cancer cell lines with retinoic acid resulted in the up-regulation of Stra6 mRNA and accumulation of Stra6 protein at the cell membrane. The data support a model in which Wnt-1 signaling synergizes with retinoids to activate retinoic acid receptor-gamma-responsive genes in human cancers.


Assuntos
Antineoplásicos/farmacologia , Neoplasias do Colo/genética , Proteínas de Membrana/biossíntese , Proteínas de Membrana/genética , Proteínas Proto-Oncogênicas/fisiologia , Tretinoína/farmacologia , Proteínas de Peixe-Zebra , Adenocarcinoma/genética , Adenocarcinoma/metabolismo , Animais , Cromossomos Humanos Par 15 , Neoplasias do Colo/metabolismo , DNA Complementar/genética , DNA Complementar/isolamento & purificação , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Neoplasias Mamárias Experimentais/genética , Neoplasias Mamárias Experimentais/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Transgênicos , Proteínas Proto-Oncogênicas/biossíntese , Proteínas Proto-Oncogênicas/genética , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/fisiologia , Células Tumorais Cultivadas , Proteínas Wnt , Proteína Wnt1
11.
Spectrochim Acta A Mol Biomol Spectrosc ; 137: 625-40, 2015 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-25244296

RESUMO

FT-IR (400-4000 cm(-1)) and Raman spectra (200-4000 cm(-1)) of uracil and 5-methyluracil (thymine) have been recorded and analyzed. The optimized molecular geometries, atomic polar tensor (APT) charges and vibrational characteristics have been studied theoretically using restricted Hartree-Fock (RHF) and density functional theory (DFT) methods. Using the Becke's exchange in conjunction with Lee-Yang-Parr's correlation functional and Becke's three-parameter hybrid method (B3LYP), the ab initio and DFT calculations were carried out to study the optimized molecular fundamental vibrational frequencies for uracil and 5-methyluracil (thymine) by employing Gaussian-03 program. The fundamental vibrational frequencies along with their corresponding intensities in IR and Raman activities and depolarization ratios of the Raman lines have also been calculated using the RHF and DFT methods employing different basis sets. In quantum chemical calculations, most of the B3LYP/6-311++G(∗∗) vibrational frequencies are in excellent agreement with the available experimental assignments and helped to propose in the reassignments of some missing frequencies in experimental study. Assuming under the Cs point group for both molecules, the distribution of normal mode of vibrations between the two species as planar (a') and non-planar (a″) for all 39 normal vibrational modes of 5-methyluracil are given by 26a'+13a″, of which 30 modes (21a'+9a″) correspond to the uracil moiety and 9 modes (5a'+4a″) to the CH3 group. Consistent assignments have been made for the internal modes of CH3 group, especially for the anti-symmetric CH3 stretching and bending modes. A possible explanation could be the planarity of pyrimidine ring and non-planarity at carbon site of methyl group which might cause the splitting of frequencies including three components due to the substitution of CH3 group at the site of C5 atom on pyrimidine ring of uracil. The three non-equivalent CH bonds of CH3 group are distinctly separated from the CH/NH ring stretching frequencies. Kekule ring stretching mode is found to be comparatively higher frequency magnitude than the mode of uracil due to the involvement of hydrogen bonding of methyl group. But, the ring breathing is found to be lower frequency magnitude compared to those for uracil which could be due to mass effect of the CH3 group in place of the hydrogen atom at the site of C5 atom on pyrimidine ring of uracil.


Assuntos
Espectrofotometria , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Timina/química , Uracila/química , Hidrogênio/química , Ligação de Hidrogênio , Conformação Molecular , Distribuição Normal , Pirimidinas/química , Teoria Quântica , Software , Temperatura , Vibração
12.
Indian J Med Microbiol ; 33(4): 593-4, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26470974

RESUMO

Dirofilaria is parasitic nematodes of domestic and wild animals that can infect humans accidentally via vectors. Its occurrence in the oral cavity is extremely rare. The most frequent presentation of human dirofilariasis is a single submucosal nodule without signs of inflammation. We hereby, report a case of human dirofilariasis affecting the buccal mucosa in a 32-year-old farmer caused by D. repens.


Assuntos
Dirofilaria/isolamento & purificação , Dirofilariose/diagnóstico , Dirofilariose/patologia , Doenças da Boca/diagnóstico , Doenças da Boca/patologia , Adulto , Animais , Histocitoquímica , Humanos , Masculino , Microscopia , Boca/patologia
13.
Antiviral Res ; 25(3-4): 281-5, 1994 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-7710274

RESUMO

Tetranitromethane, a protein nitrating agent, was tested for its ability to disinfect surfaces from viruses. Different surfaces on commercially available pocket calculators were pretreated with either the Indiana strain of vesicular stomatitis virus or the Herts' strain of Newcastle disease virus. The calculators surfaces were then sprayed with either tetranitromethane or control solutions. The calculators were incubated for 30 min at ambient temperature, and then the surfaces were wiped with sterile swabs. The swabs were placed into test tubes containing phosphate-buffered saline. Samples of the phosphate-buffered saline were then titered on appropriate cell lines by plaque assay. The results indicated that the amount of vesicular stomatitis virus and Newcastle disease virus recovered from the tetranitromethane-treated surfaces was dramatically decreased compared to the amount of virus recovered from control-treated surfaces. These data suggest that tetranitromethane may be useful to disinfect surfaces from both enveloped and non-enveloped RNA viruses.


Assuntos
Antivirais/farmacologia , Desinfetantes/farmacologia , Tetranitrometano/farmacologia , Contaminação de Equipamentos , Vírus da Doença de Newcastle/efeitos dos fármacos , Vírus da Estomatite Vesicular Indiana/efeitos dos fármacos
14.
Carbohydr Res ; 244(1): 137-47, 1993 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-8339298

RESUMO

The active site of the glucan-binding lectin (or agglutinin) (GBL) of Streptococcus sobrinus was probed by specific amino acid modifying reagents. Reagents specific for carboxylates, imidazolium, phenolic, and lysyl residues inactivated the cell bound GBL, whereas agents specific for sulfhydryl, disulfide, and guanidinium groups had no effect on the lectin. A low molecular weight alpha-(1-->6)-glucan provided partial protection against the reagents which inactivated the protein, whereas an alpha-(1-->4)-glucan, incapable of complexing with the lectin, afforded no protection. A reagent specific for tryptophan, 2-hydroxy-5-nitrobenzyl bromide (HNB) did not cause a loss of GBL activity, although N-bromosuccinimide, a reagent capable of oxidizing tryptophan and less selective than HNB, was a very effective inhibitor of the glucan-dependent cellular aggregation. In the latter case, alpha-(1-->6)-glucan did not protect. Hydroxylamine partially restored the loss of lectin activity due to treatment of the cells with N-acetylimidazole (highly specific for tyrosine), glycine methyl ester plus water-soluble carbodiimide (specific for carboxylates), and diethylpyrocarbonate (specific for histidine). Because the soluble form of GBL rapidly loses activity when purified, it was necessary to perform the chemical modification of the amino acid side chains employing the cell-bound form of the lectin. Because specific ligand [alpha-(1-->6)-glucan] protected against the inactivation of the agglutinin by selected reagents and because lectin activity could be restored in some cases, it was possible to identify likely essential amino acid residues needed for glucan binding. The results, taken together, suggest that aspartic (and/or glutamic) acid, histidine, lysine, and tyrosine are critical amino acids responsible for agglutinin activity. Present efforts are directed to the design and synthesis of glucan analogues which may serve as affinity inactivating agents of the lectin. Such glucan derivatives may be of value in studies on the role of the lectin in cariogenesis.


Assuntos
Proteínas de Bactérias , Glucanos/metabolismo , Lectinas/metabolismo , Streptococcus sobrinus/metabolismo , Aminoácidos , Sítios de Ligação , Glucanos/farmacologia , Guanidina , Guanidinas/farmacologia , Indóis/farmacologia , Cinética , Relação Estrutura-Atividade , Compostos de Sulfidrila/farmacologia , Reagentes de Sulfidrila/farmacologia
15.
J Ethnopharmacol ; 81(1): 31-41, 2002 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-12020925

RESUMO

The present ethnobotanical exploration study presents the folk medicinal uses of certain plants by tribes of the Sonbhadra district in the Uttar Pradesh state of India. One hundred and twenty five plants from 57 families, which are therapeutically used against different diseases, such as cough, cold, dysentery, diarrhoea, ulcers, diabetes, male and female weakness, snake-bite and skin disorders are covered in this report. Part of the plant used, dosage and the mode of drug administration in different ailments are described.


Assuntos
Etnobotânica , Medicina Tradicional , Fitoterapia , Extratos Vegetais/uso terapêutico , Plantas Medicinais , Vias de Administração de Medicamentos , Feminino , Humanos , Índia/etnologia , Masculino , Extratos Vegetais/administração & dosagem , Estruturas Vegetais
16.
Spectrochim Acta A Mol Biomol Spectrosc ; 117: 502-18, 2014 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-24036044

RESUMO

Raman (200-4000 cm(-1)) and FT-IR (400-4000 cm(-1)) spectra of uracil and 5-halogenated uracils (5-X-uracils; X=F, Cl, Br, I) have been recorded and analyzed in the range 200-4000 cm(-1). The optimized molecular geometries, atomic polar tensor (APT) charges and vibrational characteristics have been studied theoretically using restricted Hartree-Fock (RHF) and density functional theory (DFT) methods. Ab initio and DFT calculations [using Becke's exchange in conjunction with Lee-Yang-Parr's correlation functional and Becke's three-parameter hybrid method (B3LYP)] were carried out to study the optimized molecular fundamental vibrational frequencies for uracil and 5-halogenated uracils by employing Gaussian-03 program. Gauss View software was used to make the vibrational analysis. Raman and IR spectra have been computed theoretically for the uracil and 5-halogenated molecules. The fundamental vibrational frequencies along with their corresponding intensities in IR and Raman activities and depolarization ratios of the Raman lines have also been calculated using the RHF and DFT methods employing different basis sets. Quantum chemical calculations helped in the reassignments of some fundamental vibrational modes. Most of the B3LYP/6-311++G(**) vibrational frequencies are in excellent agreement with available experimental assignments. The ring breathing and kekule stretching modes are found to lower magnitudes compared to those for uracil which could be due to mass effect of halogen atom in place of the hydrogen atom. The C-X (X=F, Cl, Br, I) stretching frequency is distinctly separated from the CH/NH ring stretching frequencies on the pyrimidine ring. All other bands have also been assigned different fundamentals/overtones/combinations.


Assuntos
Elétrons , Halogênios/química , Pirimidinas/química , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Uracila/química , Vibração , Halogenação , Modelos Moleculares , Conformação Molecular , Teoria Quântica
17.
Spectrochim Acta A Mol Biomol Spectrosc ; 130: 313-28, 2014 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-24793482

RESUMO

Infrared (IR) and Raman spectra of uracil and 5-aminouracil have been recorded and analyzed between the region 200-4000 cm(-1). The optimized molecular geometries, atomic polar tensor (APT) charges and vibrational characteristics have been studied theoretically using restricted Hartree-Fock (RHF) and density functional theory (DFT) methods. Using the Becke's exchange in conjunction with Lee-Yang-Parr's correlation functional and Becke's three-parameter hybrid method (B3LYP), the ab initio and DFT calculations were carried out to study the optimized molecular fundamental vibrational frequencies for uracil and 5-aminouracil by employing Gaussian-03 program. The fundamental vibrational frequencies along with their corresponding intensities in IR and Raman activities and depolarization ratios of the Raman lines have also been calculated using the RHF and DFT methods employing different basis sets. In quantum chemical calculations, the most of B3LYP/6-311++G** vibrational frequencies are in the excellent agreement with available experimental assignments and helped in the reassignments of some fundamental vibrational modes. On the basis of calculated results, the assignments of some missing frequencies in the experimental study are proposed. Assuming under the Cs point group for both molecules, the distribution of normal mode of vibrations between the two species as planar (a') and non-planar (a″) are given by 25a'+11a″, of which 30 modes (21a'+9a″) correspond to the uracil moiety and 6 modes (4a'+2a″) to the NH2 group. Kekule ring stretching mode is found to be comparatively higher frequency magnitude than the mode of uracil due to the involvement of hydrogen bonding of amino group. But, the ring breathing is found to be lower frequency magnitude compared to those for uracil which could be due to mass effect of the NH2 group in place of the hydrogen atom. All other bands have also been assigned different fundamentals/overtones/combinations.


Assuntos
Espectrofotometria Infravermelho , Análise Espectral Raman , Uracila/análogos & derivados , Uracila/química , Algoritmos , Elétrons , Hidrogênio/química , Ligação de Hidrogênio , Conformação Molecular , Distribuição Normal , Pirimidinas/química , Teoria Quântica , Software , Vibração
18.
Artigo em Inglês | MEDLINE | ID: mdl-22169026

RESUMO

FTIR and Raman spectra of 5-halosubstituted uracils (5-X-uracil; X=F, Cl, Br and I) were recorded in the region 200-4000cm(-1). Assuming under the C(s) point group, the distribution of normal mode of vibrations between the two species as planar (a') and non-planar (a″) are given by 21a'+9a″, of which also correspond to the 30 modes of uracil moiety and the electro negativity of halogen group substitution causes some where mixing/shifting in their modes with other modes. The ring breathing and kekule stretching modes are observed in lower magnitudes compared to those of uracil which could be due to mass effect of halogen atom in place of the hydrogen atom. The C-X (X=F, Cl, Br and I) stretching frequency is distinctly separated from the CH/NH ring stretching frequencies on the pyrimidine ring. All other bands have also been assigned different fundamentals/overtones/combinations.


Assuntos
Halogênios/química , Uracila/análogos & derivados , Modelos Moleculares , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman
19.
J Biosci ; 36(5): 963-81, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22116295

RESUMO

Functional traits (FTs) integrate the ecological and evolutionary history of a species, and can potentially be used to predict its response as well as its influence on ecosystem functioning. Study of inter-specific variation in the FTs of plants aids in classifying species into plant functional types (PFTs) and provides insights into fundamental patterns and trade-offs in plant form and functioning and the effect of changing species composition on ecosystem functions. Specifically, this paper focuses on those FTs that make a species successful in the dry tropical environment. Following a brief overview, we discuss plant FTs that may be particularly relevant to tropical deciduous forests (TDFs). We consider the traits under the following categories: leaf traits, stem and root traits, reproductive traits, and traits particularly relevant to water availability. We compile quantitative information on functional traits of dry tropical forest species. We also discuss trait-based grouping of plants into PFTs. We recognize that there is incomplete knowledge about many FTs and their effects on TDFs and point out the need for further research on PFTs of TDF species, which can enable prediction of the dynamics of these forests in the face of disturbance and global climate change. Correlations between structural and ecophysiological traits and ecosystem functioning should also be established which could make it possible to generate predictions of changes in ecosystem services from changes in functional composition.


Assuntos
Árvores/fisiologia , Clima Tropical , Ecossistema , Folhas de Planta/fisiologia , Raízes de Plantas/fisiologia , Caules de Planta/fisiologia , Reprodução , Especificidade da Espécie
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