Ga and In-based hybrid halide perovskites as an alternative to Pb: a first principles study.

Lead-free hybrid halide perovskites have gained much attention in the field of photovoltaics due to their non-toxicity, stability and unique photo-physical properties. Sn and Ge-based ABX3 perovskites have been widely studied due to their similar electronic properties to Pb-based materials. However, the unstable oxidation state of Sn is a major challenge for the commercialization of this class of materials. To overcome this problem, here, we have designed a series of novel Ga and In-based A3B2X9-type perovskite materials incorporating the methylammonium (MA) organic cation in the A site and I- as the halide ion in the X site. In this regard, we have investigated different structural, electronic, optical and photovoltaic properties by employing the density functional theory formalism. The formation of a stable three dimensional perovskite structure is determined by the observed values of tolerance factor (TF) and octahedral factor (µ). The observed negative values of formation enthalpy manifest that our studied materials are also thermodynamically stable. The obtained band gap values reveal that our designed perovskite materials can act as semiconducting materials for application in photovoltaics. We have also investigated the optical properties of our studied materials and the observed values of dielectric function and absorption coefficient in the visible range of the electromagnetic spectrum indicate their excellent photo absorption. The observed theoretical power conversion efficiency (PCE) values reveal that (MA)3In2I9 (13.82%) and (MA)3 (Ga.50In.50)2I9 (12.8%) can be chosen as potential candidates for application in perovskite-based photovoltaics. This research provides a pathway for the development of less toxic and efficient semiconducting materials, offering exciting prospects for their utilization in optoelectronics and contributing to the ongoing efforts to advance sustainable energy technologies.

Photophysics of a Monoannulated Indigo: Intra- and Intermolecular Charge Transfer.

In the present work, the photoinduced charge-transfer (CT) behavior of 7-phenyl-6H-pyrido[1,2-a:3,4-b']diindole-6,13(12H)-dione (HCB) as a function of solvent polarity is reported by UV-vis absorption, steady-state and time-resolved fluorescence, and quantum chemical calculations. Calculated excited state energies of HCB at the B3PW91/6-31+G* level in vacuo and in solvents fulfill the energy requirements for singlet fission, which is the most promising path for the generation of highly efficient solar cells. The calculated potential energy curve for the compound reveals that the keto form is the predominant form in the ground state. Large bathochromic shifts in fluorescence with decreasing trends of quantum yield and lifetime indicate the occurrence of intramolecular CT from the indole bicycle to the indolinone moiety of HCB in highly polar solvents. The observed quenching of HCB fluorescence in different solvents without altering the spectral shape upon addition of a donor, triethylamine, is attributed to intermolecular CT, and it was examined in terms of the Stern-Volmer kinetics. The thermodynamics of photoinduced CT processes in HCB was analyzed using the measured photophysical data and cyclic voltammetric redox potentials via the Rehm-Weller equation. Analyses with the semiclassical Marcus theory suggest that both the CT processes fall under the Marcus normal region.

Boosting the Performance of Diketopyrrolopyrrole-Triphenylamine-Based Organic Solar Cells via π-Linker Engineering.

The design and development of novel and efficient donor-π-acceptor (D-π-A) type conjugated systems has attracted substantial interest in the field of organic electronics owing to their intriguing properties. In this paper, we have designed seven new and efficient D-π-A type conjugated systems (M1-M7) by a variety of π-linkers with triphenylamine (TPA) as the electron donor and diphenyldiketopyrrolopyrrole (DPP) as the electron acceptor using density functional theory (DFT) formalism for organic solar cells (OSCs). The π-linker has been substituted between the donor and acceptor for efficient electron transfer. Here, our primary focus is on narrowing the highest occupied molecular orbital-lowest unoccupied molecular orbital gaps, electronic transition, charge transfer rate, reorganization energies, and the theoretical power conversion efficiencies (PCEs). Our study reveals that the designed compounds exhibit excellent charge transfer rates. The absorption properties of the compounds have been examined using the time-dependent density functional theory (TD-DFT) method. The TD-DFT study shows that compound M2 possesses the highest absorption maxima with a maximum bathochromic shift. For a better understanding of the electron transport process of our designed compounds, we have designed donor/acceptor (D/A) blends, and each of the developed blends (FREA/M1-M7) can encourage charge carrier separation. According to the photovoltaic performance of the D/A blends, compound FREA-M2, which has a theoretical PCE of 16.53%, is the most appealing choice for use in OSCs. We expect that by thoroughly examining the relationship between structure, characteristics, and performance, this work will serve as a roadmap for future research and development of TPA-DPP-based photovoltaic materials.

Calcium phosphate nanoparticles conjugated with outer membrane vesicle of Riemerella anatipestifer for vaccine development in ducklings.

Biodegradable calcium phosphate nanoparticles offer a viable substitute for traditional adjuvants such as aluminum in vaccine production. Calcium phosphate nanoparticle adjuvanted with outer membrane vesicle (OMV) of gram negative bacteria may induce efficient immune response in the host. The present study was carried out to evaluate the potential of a mucosal vaccine formulation of calcium phosphate (CAP) nanoparticle using OMV of Riemerella anatipestifer (RA) as antigen against New Duck disease in ducks. The work was initiated with isolation, identification of RA, followed by OMV production and extraction. The CAP-OMV nanoparticle was prepared and characterized. The efficacy of the vaccine formulation and toxicity were studied in ducks. The average OMV yield in terms of protein concentration was found to be 122.33 ± 3.48 mg per liter of BHI broth. In SDS-PAGE, isolated OMVs exhibited presence of 16 distinct protein bands with molecular weight ranging from 142.1 to 12.1 kDa. Seven protein bands of 74.1, 69.3, 55.5, 50.6, 45.6, 25.1 and 13.1 kDa were detected relatively more distinct. The major bands detected in our findings were 42 kDa, 37 kDa and 16 kDa that corresponds to OmpA, OmpH, P6 respectively. The mean zeta size (±SD) and potential of the nanoparticle were 246.20 ± 0.53 nm and -25.60 ± 5.97 respectively. In transmission electron microscopy (TEM), the nanoparticles exhibited an average diameter of 129.80 ± 11.10 nm and displayed spherical morphology. The median protective dose (PD50) of CAP-OMV nanoparticle was 1881.10 µg of protein. Group I ducks received 3762 µg of protein (entrapped protein in CAP-OMV nanoparticle) via intra nasal route and it showed the highest serum IgG and secretory IgA level than other immunized groups. All experimental ducks were challenged with 10 × LD50 on 35 days of post primary immunization. Group I showed 100 % survivability in the challenge study. No gross and biochemical indication of acute or chronic toxicity were recorded. In conclusion, our results suggest that CAP-OMV nanoparticle can be a safe and efficient mucosal vaccine delivery system for RA, eliciting strong immune response in the host.

End group modulation of A-D-A type small donor molecules for DTP based organic photovoltaic solar cells: a DFT approach.

Here, five new acceptor-donor-acceptor (A-D-A) type small donor molecules C1-C5, have been designed based on the central D unit, dithieno[3,2-b:2',3'-d]pyrrole (DTP). Besides, five different A units, viz. 1,1-dicyano-methylene-5,6-dimethyl-3-indanone, 1,1-dicyano-methylene-5,6-difluoro-3-indanone, 1,1-dicyano-methylene-5,6-dichloro-3-indanone, 1,1-dicyano-methylene-5-nitro-3-indanone, and 1,1-dicyano-methylene-5,6-diamino-3-indanone are selected for these designed compounds C1-C5, respectively. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods have been employed to study the influence of different A units on the geometric, electronic, optical, charge transport and photovoltaic properties of the designed donor molecules. The results reveal that the performance of the designed donor molecules have been improved on attachment of the strong electron withdrawing A units. The observed reorganization energy (λ) values infer the electron donating nature of the designed compounds. Moreover, the absorption properties of the designed compounds manifest that compound C4 possesses the high values of maximum wavelength (λmax) in both gas and solvent phases. The properties of the D/A blends reveal that all designed blends C1-C5/C60-CN, have the capacity to promote charge carrier separation at the D/A interface. Further, the photovoltaic performance of the D/A complexes also reveal that complex C4/C60-CN, with a theoretical PCE of 18%, can be considered as the most promising candidate for application in OSCs.

RIG-I expression pattern and cytokine profile in indigenous ducks infected with duck plague virus.

The present study was undertaken to elucidate mRNA expression pattern of RIG-I and serum cytokines profile alterations in indigenous ducks of Assam, India viz. Pati, Nageswari and Cinahanh in response to natural infections of duck plague virus. Field outbreaks of duck plague virus were attended during the study period for collection of tissue and blood samples. The ducks under study were divided into three distinct groups as per health status i.e. healthy, duck plague infected and recovered. Results from the study revealed that RIG-I gene expression was significantly upregulated in liver, intestine, spleen, brain and PBMC of both infected and recovered ducks. However, fold changes in RIG- I gene expression was lower in recovered ducks as compared to infected ones which indicated continued stimulation of RIG-I gene by the latent viruses. Both serum pro and anti-inflammatory cytokines were elevated in infected ducks as compared to healthy and recovered ducks, indicating activation of inflammatory reactions in the ducks due to virus invasion. The results from the study indicated that innate immune components of the infected ducks were stimulated in order to make an attempt to resist the virus from the infected ducks.

Hopping transport in triphenylamine and indoline based semiconductors in the context of dye sensitized solar cells: A DFT Study.

Dye-sensitized solar cells (DSSCs) have drawn a significant interest due to their low production cost, light weight, better flexibility in design, and better tunability. Herein, two metal free organic dyes based on donor-π-acceptor (D-π-A) type architecture having methoxy substituted triphenyl amine (TPA) and methyl substituted indoline(IND) as the donor units, cyanoacrylic acid (CA) as the acceptor unit, and 8H-thieno [2', 3':4,5]thieno[3,2-b]thieno[2,3-d]pyrrole (TTP) unit as π-bridge are successfully designed for fabrication of DSSCs. To tune the optical properties, structural engineering has been carried out at the TTP unit via substituting different +I groups, viz., -H, -CH3, -OCH3, -CH2CH2, -SH, and -OH and different -I groups viz. -CF3, -COCH3, -COOH and -CN. Various structural, electronic and optical parameters are calculated for the designed dyes. Our study reveals that dyes substituted with electron withdrawing groups possess lower ΔH-L values for both TPA-CA and IND-CA groups of dyes. Moreover, the ESOP and GSOP values of all the dyes confirm the spontaneity of the electron injection and dye regeneration processes with respect to the conduction band of the TiO2 surface and redox potential of the I-/I3- redox couple. The absorption properties also manifest the red shift behavior of the designed dyes. Further, from the study of the structural and electronic properties of the dye-Ti5O10 clusters it is evident that the performance of the dyes get increased upon binding to the TiO2 surface. Hence, our study provides a good recommendation for further designing of dyes to enhance the performance of DSSCs.

Rational design of mixed Sn-Ge based hybrid halide perovskites for optoelectronic applications: a first principles study.

Here, we have investigated some mixed metal hybrid halide perovskite materials by employing first principle calculation method. In this regard we have designed some Sn and Ge based hybrid halide (iodide) perovskite materials incorporating dimethylammonium (DMA) organic cation and studied their structural, optoelectronic and photovoltaic properties. Observed tolerance factor (TF) and dihedral factor (µ) manifests that our studied compounds form stable three dimensional perovskite structure. Additionally, the observed negative value of formation energy indicates their thermodynamic stability. Calculated band gap values indicate the semiconducting nature of the compounds. We have also calculated the real and imaginary part of dielectric function as well as absorption coefficient of all the studied compounds. Our investigation reveals that compounds with equal amount of Sn and Ge content exhibit higher value of dielectric function and absorption coefficient among the studied compounds. Study of photovoltaic performances reveal that DMASn0.75Ge0.25I3 exhibits the highest value of theoretical power conversion efficiency (PCE) i.e., 17.42% among the studied compounds. This investigation will help researchers to design Pb-free hybrid perovskite materials which will be beneficial for the world.

Theoretical investigation of fused N-methyl-dithieno-pyrrole derivatives in the context of acceptor-donor-acceptor approach.

In this work we have theoretically investigated the optoelectronic properties of a series of acceptor-donor-acceptor type molecules by employing density functional theory formalism. We have used 1,1-dicyano-methylene-3-indanone as the acceptor unit and a fused N-methyl-dithieno-pyrrole as the donor unit. We have calculated the values of dihedral angle, inter-ring bond length, bond length alteration parameters, HOMO-LUMO gap, ionization potential, electron affinity, partial density of states, reorganization energies for holes and electrons, charge transfer rate for holes and electrons of the seven types of compounds designed via molecular engineering. Calculated IP and EA values manifest that PBDB-C2 shows excellent charge transportation compared to others. Absorption spectra of the designed compounds have been studied using the time-dependent density functional theory method. From the calculation of reorganization energy it is confirmed that our designed molecules behave more likely as donor materials. Our calculated results also reveal that compounds with electron donating substituents at the acceptor units show higher value of λ max. Absorption spectra of donor/acceptor blends show similar trends with the isolated compounds. Observed lower exciton binding energy values for all the compounds indicate facile charge carrier separation at the donor/acceptor interface. Moreover, the negative values of Gibb's free energy change also indicate the ease of exciton dissociation of all the designed compounds. The photovoltaic characteristics of the studied compounds infer that all the designed compounds have the potential to become suitable candidate for the fabrication of organic semiconductors. However, PBDB-C2 and PBDB-C4 with the highest PCE of 18.25% can become the best candidate for application in photovoltaics.

Evaluation of anti-amnesic effect of Conyza bonariensis in rats.

OBJECTIVE: Conyza bonariensis is an ornamental medicinal weed. This experiment was planned to explore the outcome of petroleum ether extract of C. bonariensis (PECB) leaves on scopolamine-induced amnesia in rats. MATERIALS AND METHODS: For impairing memory, 0.4 mg/kg (i. p.) of scopolamine was given. Fifty to 200 mg/kg of PECB was fed orally to rats and 3 mg/kg (i. p.) of tacrine was given as a standard drug. Anti-amnesic property was evaluated in Barnes maze using ANY-maze software. Following a behavioral study, acetylcholinesterase (AChE), ß-amyloid1-41, antioxidant enzymes, and cytokine levels were measured. Furthermore, reverse transcription-polymerase chain reaction was done for expression of the marker genes such as AChE, Nrf2, NF-κB, PP2A, and HO-1, whereas BDNF, TrkB, caspase-3, and Bax were measured by Western blotting. RESULTS: PECB and tacrine significantly improved memory dysfunction by decreasing escape latency in Barnes maze. At the highest dose, treatment with PECB altered the scopolamine-induced hyperactivation of AChE and ß-amyloid1-41 activity. PECB elevated the levels of superoxide dismutase, glutathione, and catalase and decreased lipid peroxidation and nitric oxide dose dependently. PECB attenuated scopolamine-induced increase of tumor necrosis factor-α and interleukin (IL)-1ß concentrations in the hippocampus with reversed diminished IL-10 level toward normal in the brain. Nrf2, HO-1, PP2A, BDNF, and TrkB were significantly upregulated with downregulation of AChE, NF-κB, Tau, Bax, and caspase-3. Different components such as beta-amyrin and alpha-amyrin were isolated from leaves of the plant. CONCLUSION: The results indicated that PECB might be a potential curative drug for the treatment of cognitive impairment.

Structural modulation of phenothiazine and coumarin based derivatives for high performance dye sensitized solar cells: a theoretical study.

A series of dyes with the D-π-A architecture has been designed and studied for dye sensitized solar cells (DSSCs). We have used phenothiazine (PTZ) and coumarin (COU) derivatives as the donor unit and benzopyrrole (BTZ) and 2-methyl-2H-isoindole-1,3-(3aH,7aH)-diene (IND) as the acceptor unit along with the azomethine group and thiophene ring as the π-spacer unit. Three electron donating groups viz. -CH3, -NH2, and -OH and four electron withdrawing groups viz. -CF3, -COCl, -F and -NO2 have been attached at the donor and the acceptor units respectively of the four unsubstituted dyes COU-BTZ, PTZ-BTZ, COU-IND and PTZ-IND. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods have been employed to investigate the structural, electronic and photochemical properties of these dyes. The study reveals that the unsubstituted dye PTZ-BTZ possesses the lowest value of ΔH-L. Our study also reveals that attachment of the -NO2 group at the acceptor unit lowers the ΔH-L values of all the dye molecules. We have observed that the excited state oxidation potential (ESOP) of all the dyes lies above the conduction band of the TiO2 semiconducting surface. However, the ground state oxidation potential (GSOP) of most of the dyes belonging to the COU-BTZ and COU-IND groups lies below the redox potential of the I-/I3- redox couple. The total reorganization energy (λtot) values of the COU-BTZ and COU-IND groups of dyes are observed to be low compared to the other groups of dyes. The study of the charge transport properties of the dyes confirms that the designed dyes will act as electron transport materials. The absorption properties of the dyes show that the COU-BTZ group of dyes possesses the maximum values of the absorption wavelength (λmax values) and attaching the -NO2 group at the acceptor unit shifts the λmax values of all the dyes to the longer region. From the study of the electronic properties of the dye-TiO2 complexes it has been observed that the performance of the dyes has been enhanced compared to the isolated dye molecules.

Tuning the charge transfer and optoelectronic properties of tetrathiafulvalene based organic dye-sensitized solar cells: a theoretical approach.

Here, we have designed a series of dyes following the donor-π-acceptor (D-π-A) architecture by incorporating tetrathiafulvalene (TTF) as the donor unit and phthalazine (PTZ), diketopyrrolopyrrole (DPP) and quinoxaline (QNX) as the acceptor units, along with the thiophene unit as a π-bridge. The designed dyes have been designated as TTF-PTZ, TTF-DPP and TTF-QNX respectively. We have used cyanoacrylic acid as the anchoring group for the dyes TTF-PTZ and TTF-DPP, while for the third dye, TTF-QNX, we used a carboxylic group. The structural, electronic and photochemical properties of the designed dyes are investigated under the regime of density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods. In this regard, the dihedral angle, energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), energy difference between the HOMO and LUMO (Δ H-L values), partial density of states (PDOS), ground state oxidation potential (GSOP), excited state oxidation potential (ESOP), ionization potential (IP), electron affinity (EA), molecular electrostatic potential surface (MEPS) analysis, reorganization energy (λ), electronic coupling matrix element (V), charge transfer rate (k CT), hopping mobility (µ hop), absorption spectra, exciton binding energy (EBE) and electron density difference (EDD) of the designed dyes are calculated. This study reveals that the dyes TTF-DPP-4 and TTF-DPP-6' exhibit the lowest Δ H-L values. The study also reveals that the attachment of the -NH2 group at the donor unit and the -NO2 and -CF3 groups at the acceptor units lower the Δ H-L values of all of the designed dyes. We have also observed that the GSOP of all the designed dyes lie below the redox potential of the I-/I3 - electrolyte couple. However, the ESOP of the TTF-PTZ and TTF-QNX groups of dyes, along with the most of the dyes belonging to the TTF-DPP group, lie above the conduction band of the TiO2 semiconducting surface. Moreover, the total reorganization energy (λ tot) values are low for the TTF-DPP and TTF-QNX groups of dyes, which confirm the better electron-hole separation efficiency in these groups of dyes. Furthermore, the absorption properties of the designed dyes indicate that the TTF-DPP groups of dyes possess the maximum absorption wavelength (λ max) values and attachment of the -CH3 group at the donor part increases the electron density of the dyes, which in turn results into the maximum red-shift. Therefore, the study reveals that the designed dyes are likely to exhibit facile charge transport. Moreover, the electronic properties of the dye-TiO2 clusters strengthen the performance of the dyes compared to those of the isolated dyes. Hence, our study provides good recommendations for the further design of dyes to enhance the performance of dye-sensitized solar cells (DSSCs).

End-capped group manipulation of non-fullerene acceptors for efficient organic photovoltaic solar cells: a DFT study.

A series of acceptors, S1-S5, has been designed based on the acceptor-π-donor-π-acceptor (A-π-D-π-A) architecture by incorporating a phenothiazine unit as the central donor unit. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods have been employed to study the effect of various end-capped groups on the geometric, electronic, optical and charge transport properties of the designed acceptor molecules. The results reveal that on increasing the electron-withdrawing nature of the end-capped groups, the performance of the acceptor molecules increases. It is also observed that on increasing the flexibility of the end-capped groups, the planarity of the molecules gets destroyed and, as a result, the performance of the acceptor molecules decreases. The investigated molecules exhibit high electron affinity (EA) and low reorganization energy for electrons (λ-), indicating the electron acceptor nature of the designed molecules. The absorption properties of the molecules manifest that compounds S2-S4 possess high values of the maximum wavelength (λmax) of absorption. We have also studied the properties of a D/A active layer by considering PffBT4T-2OD as the electron donor and arranging PffBT4T-2OD/S1-S5 molecules in a face to face manner. Properties of the D/A blend indicate that molecules S2-S4 have capacity to promote charge carrier separation at the D/A active layer. Our results provide guidelines for further designing of acceptors to enhance the performance of organic solar cells (OSCs).

Rational design of BODIPY-carbazole analogues in the context of D-π-A approach for facile charge transport: A DFT/TD-DFT study.

In this paper, we have examined the influence of torsional rigidity on the optoelectronic properties by imposing furan, pyrrole and thiophene unit on the BODIPY-carbazole based donor-acceptor systems employing density functional theory (DFT) formalism. We have designed 12 small conjugated molecules based on the donor (carbazole)-acceptor (BODIPY) approach using furan, pyrrole and thiophene unit as the bridging units. To study the torsional rigidity imparted by the bridging units we have performed potential energy surface (PES) analysis. Our study explores that among the bridging units furan and thiophene impart maximum and minimum rigidity on the systems respectively. Different parameters viz. distortion energy (ΔEdis), HOMO-LUMO gap (ΔH-L values), ionization potential (IP), electron affinity (EA), bond length alteration (BLA) parameters, dipole moment values, reorganization energies for holes (λh) and electrons (λe), electronic coupling matrix element (V), charge transfer rate (kct), hopping mobility (µhop), radiative decay rate (kr) etc. have been calculated. The absorption and emission spectra of the BODIPY based compounds have been studied using TD-DFT. NTO analysis have also been performed for the dominant electronic transitions. Our calculations predict that compounds possessing pyrrole unit as the bridging unit and compounds in which BODIPY unit is meso substituted with pyrrole unit possesses greater amount of conjugation and as a result exhibit facile charge transport.

Rational Design of Bay-Annulated Indigo (BAI)-Based Oligomers for Bulk Heterojunction Organic Solar Cells: A Density Functional Theory (DFT) Study.

In this paper, we have designed a series of oligomers based on the donor-acceptor concept. Here, acceptor bay-annulated indigo (BAI) dye and donor N-methyl-4,5-diazacarbazole (DAC) are joined by a thiophene linkage. We have substituted the 5th and 5'th positions of the acceptor unit and the 2nd position of the donor unit with various electron-withdrawing and electron-donating groups to study various structural and electronic properties of the compounds. In this regard, we have calculated the dihedral angle, distortion energy, bond length alteration (BLA) parameters, bang gap (Δ H - L ) values, partial density of states (PDOS), electrostatic potential (ESP) surface analysis, reorganization energy, charge transfer rates, hopping mobility values, and absorption spectra of the compounds. The ESP plots of the compounds indicate significant charge separation in the studied compounds. Our study manifests that the designed compounds are prone to facile charge transport.

Charge transport in isoindigo-dithiophenepyrrole based D-A type oligomers: A DFT/TD-DFT study for the fabrication of fullerene-free organic solar cells.

In this paper, we have designed a series of isoindigo-dithiophenepyrrole based oligomers with donor-acceptor architecture. The donor and acceptor units are joined by a thiophene linkage. We have substituted the 5,5'-positions of the isoindigo acceptor unit with different +I groups, viz., -CH3, -NH2, -SH, -OH, -OCH3, and -CH=CH2, and -I groups, viz., -F, -NO2, -CN, -COCH3, -COOH, and -CF3. We have studied the structural, charge injection, and transport properties employing the density functional theory (DFT) formalism. Our study explores that the presence of bulky substituents adversely affects these properties. Values of frontier orbital energies, ionization potentials, and electron affinities are calculated for each compound to predict the ease of charge injection from metal electrodes to these compounds. Most of our compounds show the ease of hole injection ability and show a large electron injection barrier. Computation of reorganization energies followed by the charge transfer integral and charge transfer rate have also been performed. Our findings reveal that compounds substituted with +I groups possess larger hole mobilities than the compounds with -I groups. Substitution of a dimer of compound 9 with -NO2 leads to the highest hole and electron mobility. Dipole moment values have also been calculated to study the charge transport properties. We have also computed the absorption properties of the compounds using the time-dependent DFT method. Our study indicates that absorption properties are changed by the attachment of substituents and can be tuned according to the requirements. Among the studied compounds, the -OCH3 substituted dimer (dimer 6) exhibits the largest bathochromic shift with a λ max of 554 nm. From this study, we can infer that our designed compounds are promising candidates for fabrication of optoelectronic devices.

Novel Isophthalohydrazide-cDB24C8 cryptand derivative for the selective recognition of fluoride ion: An experimental and DFT study.

A highly selective and sensitive novel Isophthalohydrazide-cDB24C8 cryptand derivative was developed for fluoride recognition at a very low concentration of 2.31 × 10-10 M. The binding was established by UV-Vis, fluorescence and 1H NMR titration. The receptor formed very strong H-bonded complex with fluoride, furnished a sharp new UV-Vis absorption peak at 280 nm which was also supported by the DFT-study. The fluorescence emission spectra showed large quenching up to 79.13% upon addition of fluoride.

Application of smooth exterior scaling method to study the time dependent dynamics of H2(+) in intense laser field.

A study of the multiphoton dissociation of H(2)(+) in intense laser field using the smooth exterior scaling method to calculate resonance states is presented. This method is very attractive as it does not disturb the interaction region. The wave functions calculated with this method provide indisputable proof in support of the mechanisms of the different phenomena happening during photodissociation. Wave functions corresponding to the "vibrationally trapped" (bond-hardening) states are found. A unequivocal mechanism for "bond-softening" is provided. It is observed that with an increase in intensity, the lifetime of low vibrational level increases. The mechanism for this novel phenomenon is also explained.

Molecular cloning and characterization of lingual antimicrobial peptide cDNA of Bubalus bubalis.

Antimicrobial peptides form a crucial component of innate immune system, making it a highly effective first line of defense in animals. In the study, lingual antimicrobial peptide cDNA of Bubalus bubalis has been characterized. The characterized cDNA has complete ORF of 195 bases. The signal sequence of buffalo LAP comprised of N-terminal 1-20 amino acids and mature peptide from 23-64 amino acids. The percentage of similarity of buffalo LAP and buffalo EBD at nucleotide and amino acid level was 96.4% and 92.3% respectively. The identity of buffalo LAP with cattle LAP and TAP at nucleotide level was 92.8% and 90.3%. Both at nucleotide and amino acid level buffalo LAP is closer to buffalo EBD followed by cattle LAP and TAP. Phylogenetic tree at nucleotide and amino acid level also showed close relationship of buffalo LAP with buffalo EBD, cattle LAP and TAP. The synthesized LAP fragment had antibacterial activity.

Structure-function studies of Bubalus bubalis lingual antimicrobial peptide analogs.

Antimicrobial peptides expressed on different epithelial lining are major components of the innate immune system. Based on the deduced amino acid sequence of Bubalus bubalis lingual antimicrobial peptide (LAP) cDNA (Accession No. DQ458768), five overlapping peptides LAP(23-55), LAP(42-64), LAP(21-64), LAP(1-26) and LAP(1-64) were synthesized using solid phase fluorenylmethoxycarbonyl (Fmoc) chemistry. Circular Dichroism spectroscopy of synthesized peptides revealed predominantly beta-structure for LAP(23-55,) LAP(42-64) and LAP(21-64) with less alpha-helix in different solutions. Quantitation of secondary structure indicated the highest beta-structure for all these three peptides in membrane mimetic SDS solution. The helicogenic solvent TFE could not induce helix in LAP(23-55) however TFE induced helical propensity was observed in LAP(42-64) and LAP(21-64). The quantitation of secondary structure indicated the highest ordered structure for LAP(23-55) followed by LAP(42-64) and LAP(21-64). The antibacterial activity of LAP(23-55) was found to be more potent against Staphylococcus aureus, Listeria monocytogens, Escherichia coli and Salmonella typhimurium followed by LAP(42-64) and LAP(21-64). Minimum inhibitory concentration (MIC) also showed similar trend with lowest value for LAP(23-55) followed by LAP(42-64) and LAP(21-64). Haemolysis and cytotoxicity was observed above 3 fold for LAP(21-64,) above six fold for LAP(23-55) and LAP(42-64) of their MIC. The LAP(1-26) and LAP(1-64) could not produce any characteristic CD spectra and did not show any antimicrobial activity, indicating that N- terminal of the peptide negates the antimicrobial activity.