Key of Suppressed Triplet Nonradiative Transition-Dependent Chemical Backbone for Spatial Self-Tunable Afterglow.

Highly efficient persistent (lifetime > 0.1 s) room-temperature phosphorescence (RTP) chromophores are important for futuristic high-resolution afterglow imaging for state-of-the-art security, analytical, and bioimaging applications. Suppression of the radiationless transition from the lowest triplet excited state (T) of the chromophores is a critical factor to access the high RTP yield and RTP lifetime for desirable RTP.

Vibrational Radiationless Transition from Triplet States of Chromophores at Room Temperature.

The radiationless transition rate based on intramolecular vibrations from the lowest excited triplet state (T) at room temperature [(RT)] is crucial for triplet energy harvesting in optoelectronics and photonics applications. Although a decrease of (RT) of chromophores with strong intermolecular interactions is often proposed, scientific evidence for this has not been reported. Here we report a method to predict (RT).

The Substituent-Induced Symmetry-Forbidden Electronic Transition Allows Significant Optical Limiting under Weak Sky-Blue Irradiance.

We report a novel material containing a rare metal-free dopant chromophore with controlled electronic symmetry, which exhibits strong optical limiting (OL) capabilities under weak, continuous, sky-blue irradiance. Electron-donating substituents at positions C2 and C7 of pyrene allow significant triplet generation because of the symmetrically forbidden transition between the ground state and the lowest singlet excited state, which leads to accumulation of triplet excitons in the dopant chromophore. This also leads to a small ground state absorption coefficient and induces greater absorption of sky-blue wavelengths when triplet excitons of the chromophore accumulate.

Highly Efficient Persistent Room-Temperature Phosphorescence from Heavy Atom-Free Molecules Triggered by Hidden Long Phosphorescent Antenna.

Persistent (lifetime > 100 ms) room-temperature phosphorescence (pRTP) is important for state-of-the-art security and bioimaging applications. An unclear relationship between chromophores and physical parameters relating to pRTP has prevented obtaining an RTP yield of over 50% and a lifetime over 1 s. Here highly efficient pRTP is reported under ambient conditions from heavy atom-free chromophores.

Phytoextracts as Antibacterials: A Review.

Botanicals have been cultured to flavour food, to treat health disorders and to put a stop to diseases caused by various microorganisms. The awareness of curative features of different medicinal plants has been spread among human communities. The application of herbal products as antimicrobial agents may be a better choice for the extensive and imprudent use of synthetic antibiotics.

Thermally activated delayed fluorescence and room-temperature phosphorescence in naphthyl appended carbazole-quinoline conjugates, and their mechanical regulation.

The influences of naphthyl and/or phenyl rings at the 2,4-positions of the quinolinyl fragments in carbazole-quinoline conjugates are studied. The centric phase of one of the conjugates (β-CQNN) revealed both thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP), while prompt fluorescence and RTP were observed in the non-centric phase (α-CQNN) that can regenerate the emission features of β-CQNNvia mechanical grinding. This unique observation is explained by the modulation of the higher-lying triplet (T2) energy level caused by conformational change.

Larvivorous potentiality of Puntius tetrazona and Hyphessobrycon rosaceus against Culex vishnui subgroup in laboratory and field based bioassay.

Objectives: This study assessed the predatory potentiality of two unexplored fishes, Puntius tetrazona and Hyphessobrycon rosaceus on Culex vishnui subgroup larvae in order to utilize natural resources to diminish mosquito population. Larval feeding rate was evaluated in laboratory under varying prey density and volume of water. The experiment was extended to semi field condition.

Biluminescence via Fluorescence and Persistent Phosphorescence in Amorphous Organic Donor(D)-Acceptor(A) Conjugates and Application in Data Security Protection.

Purely organic biluminescent materials are of great interest due to the involvement of both singlet and long-lived triplet emissions, which have been rarely reported in bioimaging and organic light-emitting diodes. We show two molecules 3,4,5,6-tetraphenyloxy-phthalonitrile (POP) and 3,4,5,6-tetrakis- p-tolyloxy-phthalonitrile (TOP), in which POP was found to exhibit fluorescence and persistent room-temperature green phosphorescence (pRTGP) in the amorphous powder and crystal states. Both POP and TOP show aggregation-induced emission in a tetrahydrofuran-water mixture.

Dual Emission through Thermally Activated Delayed Fluorescence and Room-Temperature Phosphorescence, and Their Thermal Enhancement via Solid-State Structural Change in a Carbazole-Quinoline Conjugate.

The emergence of single-component organic dual light emitters holds great promise for white light-emitting diodes (WLEDs) and biological detection due to the involvement of broad emission covering visible spectrum. Here we show experimental studies on dual emission of carbazole-quinoline conjugate (CQ) that exhibits both thermally activated delayed fluorescence (TADF) via reverse intersystem crossing (r ISC) from the higher-lying triplet state ( T) to the singlet state ( S) and room-temperature phosphorescence (RTP) from the lowest triplet state ( T) due to low energy gap between T and S, and energetic proximity of T with T. We found in thermal effect that the intensity of the dual features is enhanced with increasing temperatures up to 100 °C, which can be explained by a thermal-induced structural change (TISC) mechanism that compensates the emission losses due to nonradiative transitions at elevated temperatures.

Conformational switching via an intramolecular H-bond modulates the fluorescence lifetime in a novel coumarin-imidazole conjugate.

Achieving synthetic control over light-driven molecular dynamics is essential for designing complex molecule-based devices. Here we design a novel coumarin-imidazole conjugate (1) whose excited state structural dynamics are primarily controlled by a distant intramolecular H-bonding interaction within the backbone. The coumarin conjugate is based on a 1,2,4,5-aryl substituted imidazole framework (aryl = -Ph and -PhOH) covalently connected to the coumarin moiety via a C-N bond.

Hypolipidemic effect of steroid compound from Cestrum diurnum (Solanaceae: Solanales) in normocholesterolemic albino rat.

The present study was carried out to establish the hypolipidemic effect of a phyto-steroid compound isolated from the chloroform: methanol extract of fresh mature leaves of the plant Cestrum diurnum (Solanaceae: Solanales). Change in the haematological parameters was studied in normocholesterolemic albino rats after oral administration of single dose of isolated phytosteroid (2 mg/ day) up to 15 days and compared with control rats. Application of phytosteroid fraction resulted in a significant reduction in total plasma cholesterol and free cholesterol levels.

Concurrent dengue and malaria in an area in Kolkata.

Objective: To establish the nature and extent of dual dengue and malaria infections in an endemic area through a longitudinal study.

Methods: A prospective study was conducted from August 2005 to December 2010 to document the nature and extent of concurrent dengue and malaria infections in an area in central Kolkata, endemic both for dengue and malaria.

Results: Of 2 971 suspected cases of dengue fever, in 605 (20.

Isolation and identification of bioactive antibacterial components in leaf extracts of Vangueria spinosa (Rubiaceae).

Objective: The column chromatographic fraction of ethyl acetate (EA1, EA2, EA3, EA4 and EA5) leaf extracts of Vangueria spinosa (V. spinosa) were screened for antibacterial activity and phytochemical analysis.

Methods: EA3 fraction was isolated and identified by column chromatography, thin layer chromatography, spectral data analysis and phytochemical screening were used for analysis.

n-alkane profile of Argemone mexicana leaves.

An n-hexane extract of fresh, mature leaves of Argemone mexicana (Papaveraceae), containing thin-layer epicuticular waxes, has been analysed for the first time by TLC, IR and GLC using standard hydrocarbons. Seventeen long-chain alkanes (n-C18 to n-C34) were identified and quantified. Nonacosane (n-C29) was established as the n-alkane with the highest amount, whilst octadecane (n-C19) was the least abundant component of the extracted wax fraction.

Determination of the n-alkane profile of epicuticular wax extracted from mature leaves of Cestrum nocturnum (Solanaceae: Solanales).

An n-hexane extract of fresh, mature leaves of Cestrum nocturnum (Solanales: Solanaceae) containing thin layer epicuticular waxes was analysed by thin-layer chromatography, infrared and gas liquid chromatography using standard hydrocarbons. Seventeen long chain alkanes (n-C(18) to n-C(34)) were identified and quantified. Hentriacontane (n-C(31)) was established as the major n-alkane, while nonadecane (n-C(19)) was the least abundant component of the extracted wax fraction.

A review on Anopheles subpictus Grassi--a biological vector.

Anopheles subpictus is a complex of four isomorphic sibling species A, B, C and D and is recognized as a primary vector of malaria, a disease of great socio-economic importance, in Australasian Zone, Celebes, Portuguese Timor and South East Asia and a secondary vector in Sri Lanka. This species is also a vector of some helminth and arboviruses. This species has been reported so far from nineteen countries of the Oriental and Australasian Zones.

In vitro synergistic effect of doxycycline & ofloxacin in combination with ethanolic leaf extract of Vangueria spinosa against four pathogenic bacteria.

Background & Objectives: The in vitro antibacterial activity of ethanolic leaf extract of Vangueria spinosa Roxb. (Rubiaceae) alone and in combination with antibiotics (doxycycline and ofloxacin) by means of fractional inhibitory concentration indices (FICI) as well as by the use of time-kill assays against one Gram-positive bacterium (Staphylococcus aureus) and three Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa) was studied.

Methods: Antibacterial activity was assayed by using the microdilution method.

Water quality assessment near an industrial site of Damodar River, India.

An assessment on the water quality parameters coliform including the bacterial abundance from a point source of river Damodar (24 degrees 26(') N and 86 degrees 53(') E), West Bengal, India was carried out during the period of 2004-2007. The site received mining and industrial effluents from the collieries and industries. The water samples collected on a monthly basis revealed the presence of the coliform bacteria Escherichia coli and Streptococcus sp.

Antibacterial potentiality of Argemone mexicana solvent extracts against some pathogenic bacteria.

The sensitivity of two Gram positive (Staphylococcus aureus and Bacillus subtilis) and two Gram negative (Escherichia coli and Pseudomonas aeruginosa) pathogenic multi-drug resistant bacteria was tested against the crude extracts (cold aqueous, hot aqueous, and methanol extracts) of leaves and seeds of Argemone mexicana L. (Papaveraceae) by agar well diffusion method. Though all the extracts were found effective, yet the methanol extract showed maximum inhibition against the test microorganisms followed by hot aqueous extract and cold aqueous extract.