Pyrenebutylamidopropylimidazole as a multi-analyte sensor for 3,5-dinitrosalicylic acid and Hg²⁺ ions

Kumar, A.,Pandith, A.,Kim, H.S. Elsevier [etc.] 2016 Journal of luminescence Vol.172 No.-

<P>Pyrenebutylamidopropylimidazole 1 was synthesized as a sensor for 3,5-dinitrosalicylic acid (3,5-DNSA) and 5-nitrosalicylic acid (5-NSA), among other aromatic carboxylic acids, and Hg2+ among different metal ions in PBS-EtOH (5:95; pH=7.4) solutions. The sensing ability of probe 1 was examined using fluorescence and H-1 NMR spectroscopy. The presence of 3,5-DNSA and 5-NSA resulted in 97% and 50% quenching, respectively, of the emission intensity at lambda(max)=379 nm of probe 1, whereas the presence of Hg2+ resulted in the selective development of an excimer band at 476 nm with simultaneous quenching of the monomer emission. Probe 1 had good association constants with 3,5-DNSA (K-a=4.38 x 10(4) M-1) and 5-NSA (K-a=2.37 x 10(4) M-1) in a 1:1 stoichiometry in PBS-EtOH (5:95; pH=7.4) solution, whereas the presence of Hg2+ led to the formation of a 1:2 complex between Hg2+ and probe 1 with a high association constant (K-a=9.76 x 10(4) M-1). These results were further supported by energy-minimization density functional theory calculations. (C) 2015 Elsevier B.V. All rights reserved.</P>

Ab initio molecular dynamics simulations of excited hydrogen halides and methyl halides

Kumar, A.,Lee, E.C.,Lee, S.,Kolaski, M. North Holland ; Elsevier Science Ltd 2009 Chemical physics letters Vol.482 No.4

Using excited-state ab initio molecular dynamics simulations employing the complete-active-space self-consistent-field approach, we study the mechanism of photodissociation in terms of time evolution of structure, kinetic energy, charges and potential energy for the first excited state of hydrogen halides and methyl halides. Although the hydrogen halides and methyl halides are similar in the photodissociation mechanism, their dynamics are slightly different. The presence of the methyl group causes delay in photodissociation as compared to hydrogen halides.

Pyrene-appended imidazolium probe for 2,4,6-trinitrophenol in water

Kumar, A.,Pandith, A.,Kim, H.S. Elsevier Sequoia 2016 Sensors and actuators. B, Chemical Vol.231 No.-

Pyrene-appended imidazolium salts (1-3) were synthesized for sensing 2,4,6-trinitrophenol (TNP); the salts selectively and sensitively detected TNP in a pH 7.4 PBS-DMSO (99.5:0.5v/v) solution. The binding of TNP to probe 3 completely quenched its green excimer emission because of the loss of π-π interactions between the pyrene rings and energy transfer from electron-rich pyrene to electron-deficient TNP. Probe 3 showed the highest association constant with TNP (K<SUB>a</SUB>=8.34x10<SUP>6</SUP>M<SUP>-1</SUP>) in a 1:2 stoichiometry; the limit of detection (LOD) of TNP in a pH 7.4 PBS-DMSO (99.5:0.5v/v) solution was 10nM. Probe 3 also detected TNP in tap water and river water with an LOD of 10nM and a good association constant; the calculated LOD was 0.067 ppb. Filter paper strips coated with 3 detected TNP in an aqueous solution. The interactions of TNP with probes 1-3 were investigated by UV-vis, fluorescence, and <SUP>1</SUP>H NMR spectroscopies as well as density functional theory calculations.

EVALUATION OF BEST SEX AND ECONOMIC SLAUGHTER WEIGHT ON STANDARD FEEDING IN LARGE WHITE PIGS UNDER INDIAN CONDITIONS

Kumar, A.,Barsaul, C.S. Asian Australasian Association of Animal Productio 1991 Animal Bioscience Vol.4 No.3

A comparative study was conducted in total thirty six large while weaner pigs of about 15 kg body weight namely boars, barrows and gilts to evaluate best sex and economic slaughter weight with one standard ration. In 159 days study period feed consumption, growth, feed conversion ratio and carcass quality were judged in all sexes of pigs at 50, 70 and 90 kg body weight. It was noted that upto 70 kg body weight the growth in boars and gills 46.0 and 49.0 kg and feed conversion ratio 4.83 and 4.81 were superior and economical over the barrows, which were 45.5 kg and 4.95. Later on there were too many fluctuations in growth and feed conversion ratio in all sexes of pigs, which would be uneconomical. Carcass quality was also better in boars and gilts than barrows, No boar taint was noted in most of the boar carcasses. Hence it is concluded that boars and gilts can be raised upto the 70 kg body weight for economic pork production.

Quality and Fertility of Post Thaw Sephadex Filtered Bull Semen

Kumar, A.,Singh, J.,Nanda, A.S.,Pangaonkar, G.R. Asian Australasian Association of Animal Productio 2004 Animal Bioscience Vol.17 No.6

The present investigation was carried out to assess the effect of Sephadex (G-15) filtration on the post thaw bull semen quality and conception rate. Post thaw unfiltered (control) and Sephadex filtered semen from four healthy bulls (three cross bred and one pure bred Holstein Friesian) were subjected to microscopic examination viz. sperm concentration, individual motility, live sperm count and sperm morphology. Sixty-two healthy, normal cycling crossbred cows were inseminated with post thaw unfiltered (n=32) and filtered semen (n=30). Sephadex filtration of post thaw semen significantly (p<0.05) decreased total sperm concentration and sperm with abnormal head, mid piece and tail. The overall average total sperm concentration, head and tail defects in filtered semen decreased significantly (53.4, 1.2 and 6.4 million) than in the unfiltered semen (80.4, 2.4 and 15.7 million, respectively). However, after filtration significant (p<0.05) increase in overall average motile and live sperm concentration were observed (38.8 and 38.0) as compared to unfiltered semen (29.2 and 32.0 million, respectively). The overall conception rate recorded was 21.9% with post thaw unfiltered semen and 56.7% with filtered semen. It was concluded that Sephadex filtration of post thaw semen improved its quality and conception rate.

New 1,8-naphthalimide-conjugated sulfonamide probes for TNP sensing in water

Kumar, A.,Chae, P.S. Elsevier Sequoia 2017 Sensors and actuators. B Chemical Vol.240 No.-

Two 1,8-naphthalimide (NPI)-conjugated sulfonamide probes (1 and 2) were synthesized for sensitive detection of 2,4,6-trinitrophenol (TNP) in aqueous media. In a PBS buffer, probe 1 (with two NPI units) showed an emission spectrum with λ<SUB>max</SUB>=484nm while probe 2 (with only one NPI unit) gave an emission spectrum with λ<SUB>max</SUB>=383nm. Probe 1 showed aggregation-induced emission enhancement (AIEE) in a mixture of DMSO: H<SUB>2</SUB>O, but this emission was completely quenched in the presence of 2 equiv. of TNP. Partial de-aggregation of the nanoparticles and a conformational change of probe 1 induced by strong binding of the probe with TNP are mainly responsible for its sensitive TNP detection. Probe 1 provided sensitive detection of TNP in sea water, with observed and calculated limits of detection (LOD) of 3nM and 5.86 ppt, respectively. In addition, filter paper strips coated with probe 1 were successfully utilized for TNP detection with high sensitivity.

Selective fluorescence sensing of 3,5-dinitrosalicylic acid based on pyrenesulfonamide-functionalized inorganic/organic hybrid nanoparticles

Kumar, A.,Lee, J.Y.,Kim, H.S. THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2016 Journal of Industrial and Engineering Chemistry Vol.44 No.-

<P>Pyrenesulfonamide-functionalized inorganic/organic hybrid Fe3O4@SiO2 nanoparticles were prepared for the selective and sensitive detection of 3,5-dinitrosalicylic acid (3,5-DNSA) among a series of aromatic carboxylic acids. The monomer fluorescence emission intensity of pyrene at 380 nm was switched off on interaction with 3,5-DNSA. The minimum detection limit for 3,5-DNSA was 10 nM in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES)-CH3CN (8:2; pH 7.4). The inorganic/organic hybrid Fe3O4@SiO2 nanoparticles were characterized using Fourier-transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. (C) 2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.</P>

Electro- and opto-resistive switching behaviors of the Nb doped SrTiO₃ films

Kumar, A.,Dho, J. Elsevier 2013 CURRENT APPLIED PHYSICS Vol.13 No.4

Nb doped SrTiO<SUB>3</SUB> (Nb:STO) films were deposited on (100) SrTiO<SUB>3</SUB> substrates using a pulse laser deposition technique. The effects of deposition pressure on their structural, electrical and optical properties were investigated. Decrease in deposition pressure lead to decrease in grain size and average surface roughness. Various optical parameters such as refractive index, extinction coefficient, and band gap were calculated by applying the envelop or extrapolation methods using the transmittance data obtained from a UV/Vis spectrophotometer. A systematic decrease in resistivity and increment of negative charged carriers was observed with decreasing deposition pressure. Experimental results exhibited electro- and opto-resistive switching behaviors with a resistive transition from high resistance state to low resistance state on the application of current-pulse or UV light. Multi-level resistance states have also been demonstrated using a train of current pulses of different magnitudes or a simultaneous application of current and UV light. Such observed phenomenon makes Nb:STO a potential candidate to be used in future for the fabrication of multi-level memory devices and transparent thin films transistors.

Electronically tuned sulfonamide-based probes with ultra-sensitivity for Ga³⁺ or Al³⁺ detection in aqueous solution

Kumar, A.,Chae, P.S. Elsevier Pub. Co 2017 Analytica chimica acta Vol.958 No.-

<P>Three electronically tuned fluorescent probes (1-3) were synthesized by conjugating a fluorescent unit to N,N-bis-(hydroxyethyl)ethylenediamine. Probe 1 bearing an electron-deficient naphthalenedimide unit did not give a fluorescence response to the presence of various metal ions including monovalent metal ions (Na+, K+, and Ag+), divalent metal ions (Ca2+, Cd2+, Co2+, Ni2+, Cu2+, Hg2+, Pb2+, and Zn2+) and trivalent metal ions (Al3+, Ga3+, Fe3+, and Cr3+) in an aqueous solution. By contrast, probes 2 and 3 possessing 1,8-naphthalimide and pyrene fluorophores, respectively, exhibited selective fluorescent 'OFF-ON' behaviors as a result of Ga3+/Al3+ binding among the diverse metal ions, suggesting the importance of fluorophore electronic character with regard to metal ion sensing. The ethylenediamine analog of probe 3, corresponding to probe 4, was unable to yield a significant change in fluorescence intensity in the presence of any metal ions tested here, revealing the essential role of two hydroxyl groups for metal ion binding. A high association constant of Ka = 2.99 x 10(5) M-1 was obtained for probe 3 with Ga3+, with a limit of detection (LOD) of 10 nM. This LOD is the lowest value known for Ga3+ detection using chemical sensors. Along with an increase in aggregate sizes, PET suppression of probes upon metal ion binding was the primary contributor to the enhancement in fluorescence emission necessary for the sensitive detection of the target ions. The probe-metal ion complexes were fully characterized via TEM, FE-SEM, H-1 NMR, fluorescence spectroscopy techniques and DFT calculations. (C) 2016 Elsevier B.V. All rights reserved.</P>

Novel dithiols as capping ligands for CdSe quantum dots: optical properties and solar cell applications

Kumar, A.,Huy, B.,Kumar, B.,Kim, J.,Dao, V. D.,Choi, H. S.,Lee, Y. I. Royal Society of Chemistry 2015 Journal of Materials Chemistry C Vol.3 No.9