Ultrafast photoinduced enhancement of nonlinear optical response in 15-atom gold clusters on indium tin oxide conducting film

We show that the third order optical nonlinearity of 15-atom gold clusters is significantly enhanced when in contact with indium tin oxide (ITO) conducting film. Open and close aperture z-scan experiments together with non-degenerate pump-probe differential transmission experiments were done using 80 fs laser pulses centered at 395 nm and 790 nm on gold clusters encased inside cyclodextrin cavities. We show that two photon absorption coefficient is enhanced by an order of magnitude as compared to that when the clusters are on pristine glass plate. The enhancement for the nonlinear optical refraction coefficient is ~3 times. The photo-induced excited state absorption using pump-probe experiments at pump wavelength of 395 nm and probe at 790 nm also show an enhancement by an order of magnitude. These results attributed to the excited state energy transfer in the coupled gold cluster-ITO system are different from the enhancement seen so far in charge donor-acceptor complexes and nanoparticle-conjugate polymer composites.Comment: To appear in Optics Express (2013); http://dx.doi.org/10.1364/OE.21.00848

Large scale harvest of lizardfish juveniles along the Kerala coast

Lizardfishes are one of the major demersal resources, which contribute 5.3% of the total marine landings of Kerala. They are locally known as “Aranameen” and are sold and consumed in fresh and dried condition in Kerala, and support a regular fishery. The lizardfish landings in commercial trawlers along Kerala during the period 2007-2016 was 1,05,848 tonnes (t), with an annual average catch of 10,858 t, which constituted 5.3% of the total marine landings of Kerala

Length-weight relationships of three reef-associated fishes Lutjanus gibbus, Pinjalo lewisi and Pristipomoides filamentosus off Kochi, southwest coast of India

Length-weight relationships (LWRs) of three reef-associated fishes belonging to the family Lutjanidae viz ., Lutjanus gibbus (Forsskal, 1775), Pinjalo lewisi Randall, Allen & Anderson, 1987 and Pristipomoides filamentosus (Valenciennes, 1830), were estimated based on 548 samples collected from trawl net and hook and line fishery off Kochi, southwest coast of India. Sampling was done at Kochi (Lat. 09°56′327′′N, Long. 76°15′764′′E) and Munambam (Lat. 10°10′965′′N, Long. 76°10′258′′E) landing centers from May 2017 to November 2019. The estimated coefficient (b value) ranged from 2.597 ( P. lewisi , N = 89) to 2.902 (P. filamentosus , N = 240). Coefficient of determination (r2) ranged from 0.906 ( L. gibbus ) to 0.952 ( P. filamentosus), indicating a strong functional LWRs that were highly significant (p <0.001). The study reports the new maximum total length (TLmax) for P. lewisi and also records first estimates of length-weight relationships for three major species of snappers from the region. The generated LWR parameters will be of great importance in evaluating the biological changes in fish stocks and for developing sustainable management measures for snappers in the southeastern Arabian Sea

Molecular Mechanisms Involved in Biosynthesis and Regulation of Carotenoids in Plants

Carotenoids are coloured compounds beneficial to plants and humans. Some of the major health benefits carotenoids provide include Vitamin A precursors and, antioxidants besides being involved in several physiological functions. Even though several carotenoids are synthesised by plants, only a few like beta/ alpha carotenes and cryptoxanthin serve as Vitamin A precursors. The rest are useful as antioxidants. To draw maximum benefits from carotenoids, we need to incorporate these in crop improvement programmes for enhancing available Vitamin A precursor carotenoids. Therefore, it is essential to study biosynthesis of carotenoids, their genetics and their control. In this review, we focus on factors regulating carotenoid biosynthesis, metabolism and storage in plastids. Transcriptional and genetic control of carotenoid production in plants is discussed in the review using several mutants too. Further, environmental regulation of carotenoid biosynthesis is also highlighted. Carotenoid-rich fruits and vegetables have greater economic value owing to their health-promoting effects. Besides,carotenoids have several industrial applications. Therefore, knowledge of regulation mechanism in carotenoid production in plants can help develop crop varieties or technologies, thus generating carotene-rich fruits and vegetables

Note on landings of pregnant sharks in Cochin Fisheries Harbour, Kerala

Sharks formed the major bycatch of pelagic longline and gillnet fishery which target high value fishes like tunas until recently. However, owing to the great demand for fresh and dried shark meet in the domestic market and expansion of fishing to distant waters there is targeted fishing for sharks. In India, major portion of the sharks caught by mechanized longliners and gillnetters are landed in Cochin Fisheries Harbour and Thoothoor fish landing centre. The annual catch of sharks in Kerala during 2017 was estimated at 2936 tonnes, of which 80% was landed in Cochin Fisheries Harbour

First Record of African Angel Shark, Squatina africana (Chondricthyes: Squatinidae) in Indian Waters, Confirmed by DNA Barcoding

A single specimen of African angel shark, Squatina africana (Regan, 1908) was caught off Lakshadweep (11°5′47″ N; 72°2′21″ E), India in September 2016. The present study is a new report of the above species from Indian waters. In addition to classical methodologies, DNA barcoding was also adopted for species identification. The 650 bp-long region of mitochondrial Cytochrome Oxidase subunit I was sequenced to obtain the DNA barcode for the species under study. The sequence divergence value within species and between species was calculated using MEGA V.7.0, where Kimura 2 parameter (k2p) model was chosen as a distance model. The average k2p distance separating individuals within species was 1.76% and inter specific divergence was 8–10%. A neighbour joining network was constructed to provide a graphical representation of divergence between the species. Using the maximum identity with Gen Bank database, K2P divergence distance, NJ-network and traditional morphological approach, we could identify the given specimen as a mature male African angel shark

Giant sized rays landed at Cochin Fisheries Harbour

On 4th March 2017, three huge rays - two Mobula tarpacana and one Manta birostris were landed at Cochin Fisheries Harbour. They were caught in long lines, which were operated for skipjack tuna. These rays caught off Ratnagiri coast at a depth of 500m weighed around 400 kg each. Of these, Mobula tarpacana locally called 'Kakkathirandi' measured 2.4 m in disc width (DW)

Length weight relationships of demersal reef fishes from south west coast of India

Length weight relationship of thirteen demersal reef fish species in three genera in two families Serranidae and Lutjanidae from northern Arabian Sea was estimated. A total of 7344 specimens from the thirteen species were used for the study. Sample sizes ranged from 25 to 4428 mm with the smallest sample size being that of Cephalopholis sonnerati. New maximum length was estimated for Epinephelus areolatus, Pristipomoides typus and Pinjalo lewisi. Significant differences in the slopes of length weight relationships between males and females for Epinephelus diacanthus, was observed. Fishes studied are in the Least Concern (LC) category in the IUCN list

Report on the landing of the critically endangered Rhinobatid Acroteriobatus variegatus (Nair & Lal Mohan, 1973) with some insights into its reproductive biology

A single specimen of a gravid female of the stripenose guitarfish, Acroteriobatus variegatus was landed as by-catch by a tuna hook and line at Sakthikulangara, Kerala from a depth of 110-130 m. The species is categorized as ‘critically endangered’ by IUCN. The morphometric characteristics of A. variegatus are described for the first time since its original description by Nair and Lal Mohan (1973) from Gulf of Mannar. The present study provides preliminary insights into its reproductive biology. The mode of reproduction in A. variegatus is aplacental yolk sac viviparity with low uterine fecundit

Seasonal fishery of blue swimmer crab at Attupuram landing centre

Recent visits to the landing centers of A ttupuram - K athiyalam area in Thrissur district of Kerala, it is learnt that a seasonal fishery for Blue swim m er crab - Portunuspelagicus- is existing in this area for a few years. Every year during July-August period, gillnet fishing for blue swim m er crab (BSC) is active here. Of the harvested catch 99% is BSC and the rest the Three spotted crab, P sanguinolentus. Crabs are also caught by hand-picking during the season when young boys are engaged in this activity. The BSC caught in the gillnets were bigger in size and males were dominating