A comparative study of chromium oxide clusters grafted on mesoporous silica SBA-15 was carried out using samples synthesized by one-pot, impregnation and Cr-polycation sol grafting methods. The ...nature of CrO
x
species incorporated into SBA-15 by direct hydrothermal one-pot method as well as impregnation of Cr(NO
3
)
3
·9H
2
O and Cr-polycation precursors was characterized by XRD, BET isotherms, UV–Vis DRS, FTIR, TGA, O1s XPS,
29
Si-MAS NMR, H
2
-TPR, NH
3
-TPD, SEM and TEM. Powder XRD did not show the presence of Cr
2
O
3
in the calcined samples obtained by one-pot method. It, however, shows the rhombohedral clusters of α-Cr
2
O
3
dispersed over SBA-15 for CrO
x
/SBA-15 samples prepared by impregnation and polycation sol grafting methods. The absorption band at 296 nm, observed for Cr
3+
in solution, is absent for the aqueous Cr-polycation sol. There is evidence that the presence of chromium precursor in the reaction medium can influence the morphology of SBA-15 as seen in the SEM micrographs. Charge transfer transitions demonstrate the insertion of CrO
x
species on SBA-15 matrix synthesized by one-pot method. Cr-polycation grafted SBA-15 sample shows unique vibrational features at 573 and 624 cm
−1
attributed to extra-framework CrO
x
species. The ratio of Cr
6+
/Cr
3+
species present in CrO
x
/SBA-15 samples depends on the Cr-precursor employed for grafting on SBA-15. One-pot synthesized samples predominantly contain coordinated water (δ
H–O–H
at 1,635 cm
−1
) on SBA-15 while impregnated samples show water molecules associated with CrO
x
species (δ
H–O–H
at 1,594 cm
−1
).
Bhaga Basin has complex mountainous terrain; little study has been done on the spatial and temporal characteristics of snow cover in the region. The Moderate Resolution Imaging Spectroradiometer ...(MODIS) 8-day snow cover products between 2001 and 2012 for winter period (November-April) have been used to study the variation in snow cover area (SCA). The statistical analysis based on non-parametric Mann Kendall and Sen's slope methods have been used for detecting and estimating trends for climatic variables (temperature and snowfall) and SCA for winter period. Results of statistical analysis indicate rise in minimum temperature (0.02 °C year
−1
) and fall in maximum temperature (0.17 °C year
−1
). It also shows decrease in mean seasonal snowfall (0.07 cm year
−1
). The seasonal SCA was found to decrease at the rate of 0.002% year
−1
. This study indicates that the climate change is probably one of the major causes for depleting SCA.
The conservation of biodiversity is essential for human survival and quality of the environment. Lakshadweep islands are vulnerable to global change and the representing remnant natural vegetation. ...Landscape fragmentation, disturbance regimes and biological richness have been studied using geo-spatial techniques. Littoral vegetation is the only natural vegetation type of Lakshadweep islands. Altogether 59 patches of the littoral vegetation occupying an area of 137.2 ha were identified. 58.06% of the littoral vegetation patches belongs to the patch-size class of <5 ha. The remnant natural vegetation surviving with patches of less than 20 ha size indicates severe anthropogenic pressure. The fragmentation of littoral vegetation habitat into smaller isolated patches poses one of the key threats to biodiversity and coastal environment. Phytosociological observations revealed distinct plant communities and presence of invasive species in littoral vegetation. The high disturbance areas accounted for 59.11% area of the total vegetation. The overall spatial distribution of biological richness (BR) in Lakshadweep shows maximum BR at low level (78%), followed by medium (19%), high (2%) and very high (1%). The study emphasises the importance of conserving the remnant natural vegetation, which is critically endangered.
Proteins that selectively transport water across the membranes of cells are recognized as important in the normal functioning of the body systems of vertebrates. There are 13 known mammalian ...aquaporins (AQP0 to AQP12), some of which have been shown to have unexpected cellular roles beyond transmembrane water transport. The availability of non-mammalian vertebrate animal models has the potential to provide insight into the emergence of diverse function in the aquaporins. The domesticated chicken (Gallus gallus) is the premier avian model for biological research; however, only a limited number of studies have compared chicken and mammalian aquaporins. The identification of aquaporins that share functional motifs or are expressed in the same tissues in human and chicken could allow the further functional analyses of homologous aquaporins in both species. We hypothesize that integrative analyses of protein sequences and body site expression of human, mouse, rat and chicken aquaporins has the potential to yield novel biological hypotheses about the unexpected cellular roles of aquaporins beyond transmembrane water transport.
A total of 76 aquaporin transcript models derived from 47 aquaporin genes were obtained for human, mouse, rat and chicken. Eleven body sites (brain, connective tissue, head, heart, liver, muscle, ovary, pancreas, small intestine, spleen and testis) were identified in which there is suggested expression of at least one mammalian and one chicken aquaporin. This study demonstrates that modern on-line analysis tools, a novel matrix integration technique, and the availability of the chicken genome for comparative genomics and expression analysis enables hypothesis generation in several important areas including: (i) alternative transcription and speciation effects on the conservation of functional motifs in vertebrate aquaporins; (ii) the emergence of basolateral targeting in mammalian species; (iii) the potential of the cysteine-rich AQP11 as a possible target in the pathophysiology of neurodegenerative disorders such as autism that involve Purkinje cells; and (iv) possible impairment of function of pancreas-expressed AQP12 during pancreatotropic necrosis in avian influenza virus infection.
The investigation of aquaporin function in chicken and mammalian species has the potential to accelerate the discovery of novel knowledge of aquaporins in both avian and mammalian species.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Up-scaling the evaluation of threat status of biodiversity from species to ecosystem level has remained for long a research challenge in global conservation science. To meet this challenge, the ...present study makes an attempt toward actionable conservation prescription and assigning a threat category scheme for forest ecosystems. The scheme sets the quantitative criteria for evaluation of cumulative anthropogenic threats in grid cells, such as deforestation, degradation, fragmentation, forest fires and biological invasions. Adopting the convention of IUCN, five conservation status categories (i.e. Critically Endangered, Endangered, Vulnerable, Near Threatened, Least Concern) have been similarly adopted for the forest ecosystems facing these threats. The operational success of this scheme of threat categories at ecosystem level has been strengthened by remote sensing and field data generated for the forest ecosystems of Odisha, India. The threat category status of the forest ecosystems were identified by creating grids (5km×5km) in GIS and assigned the degree of the threats for each grid. The database on deforestation was generated using topographical maps of 1935 and remote sensing data of 1975 and 2010. The degradation in forest ecosystems have been assessed based on the change in forest canopy closure, fragmentation pattern, forest fire distribution and impact of biological invasions. The analysis for conservation priority hotspots complements an assessment of the threatened ecosystems undergoing remarkable level of multiple threats. Areas under the danger of cumulative anthropogenic threats would have a higher priority. 5.8% grids of existing forest had included under the category of conservation priority hotspot-I, followed by 12.4% in conservation priority hotspot-II, and 12.5% in conservation priority hotspot-III. An integrated approach involving the cumulative anthropogenic threat indicators have been found to be the most appropriate tool to empirically evaluate the threat status of the forest ecosystems. Finally, identification of ecosystems especially those facing increasing extinction risks, as attempted in the present study, can help in devising an appropriate policy and management agenda for the conservation and sustainable use of biodiversity.
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