Does the position of the electron-donating nitrogen atom in the ring system influence the efficiency of a dye-sensitized solar cell? A computational study

Electronic structure of the XeOF₂ molecule and its two complexes with HX (X= F, Cl, Br, I) molecules have been studied in the gas phase using quantum chemical topology methods: topological analysis of electron localization function (ELF), electron density, ρ(r), reduced gradient of electron density |RDG(r)| in real space, and symmetry adapted perturbation theory (SAPT) in the Hilbert space. The wave function has been approximated by the MP2 and DFT methods, using APF-D, B3LYP, M062X, and B2PLYP functionals, with the dispersion correction as proposed by Grimme (GD3). For the Xe-F and Xe=O bonds in the isolated XeOF₂ molecule, the bonding ELF-localization basins have not been observed. According to the ELF results, these interactions are not of covalent nature with shared electron density. There are two stable F₂OXe^…HF complexes. The first one is stabilized by the F-H^…F and Xe^…F interactions (type I) and the second by the F-H^…O hydrogen bond (type II). The SAPT analysis confirms the electrostatic term, E_elst ⁽¹⁾ and the induction energy, E_ind ⁽²⁾ to be the major contributors to stabilizing both types of complexes.

     

Fabrication of nanofiber coated with l-arginine via electrospinning technique: a novel nanomatrix to counter oxidative stress under crosstalk of co-cultured fibroblasts and satellite cells

The objective of this study was to synthesize and characterize novel polyurethane (PU)-nanofiber coated with l-arginine by electrospinning technique. This study determined whether l-arginine conjugated with PU-nanofiber could stimulate cell proliferation and prevent H₂O₂-induced cell death in satellite cells co-cultured with fibroblasts isolated from Hanwoo (Korean native cattle). Our results showed that l-arginine conjugated with PU nanofiber could reduce cytotoxicity of co-cultured satellite cells. Protein expression levels of bcl-2 were significantly upregulated whereas those of caspase-3 and caspase-7 were significantly downregulated in co-culture of satellite cells compared to those of monoculture cells after treatment with PU-nanofiber coated with l-arginine and which confirmed by Confocal microscope. These results suggest that co-culture of satellite cells with fibroblasts might be able to counter oxidative stress through translocation/penetration of antioxidant, collagen, and molecules secreted to satellite cells. Therefore, this nanofiber might be useful as a wound dressing in animals to counter oxidative stresses.     

Aeromycoflora in the Central Milk Dairy of Calcutta, India

Intramural aeromycological survey was performed at the Central Milk Dairy, Calcutta, covering eight locations within the Dairyusing Burkard personal volumetric air sampler. The locations were butter cold storage (−2 °C), cold store (8 °C), packaging section (23 °C), milk processing section (24 °C), reconstituent of skimmed milk (24 °C), quality control lab (25 °C), raw milk reception (28 °C) and loading dock (26 °C). A number of fungal spores, conidia and mycelia were recorded in different rooms: the highest spore quantity was recorded in the packaging section (23 °C) and the minimum at the butter cold store (−2 °C). The dominant spores consisted of Aspergillus niger, A flavus,Cladosporium sp., Fusarium sp., Curvularia sp.,Alternaria sp., Torula sp., Myrotheciumsp., Helminthosporium sp., Periconia sp.,Nigrospora sp. and Pithomyces sp. This revised version was published online in June 2006 with corrections to the Cover Date.     

Aeromycoflora of an agricultural farm in West Bengal,India: A five-year study (1994–1999)

A five-year (1994–1999) continuous survey of aeromycoflora had been carried out in an agricultural farm at a suburban area of Greater Calcutta. The sampling was carried out with Burkard volumetric spore trap placed 0.5?meter above the ground level at the centre in a small plot in a rice field. A total of 26 fungal spore types were identified microscopically. The most abundant types were Basidiospores (21.85–5.59%) followed by Cladosporium, Periconia, Nigrospora, Aspergilli group, Ascospores. The seasonal periodicity of the major dominant types had maxima in autumn, during the month of October. This coincided with the harvesting period of the rice crop during rainy season. In Petri plate exposure of nutrient media, different species of aspergilli group, Alternaria, Cladosporium, Curvularia, Nigrospora, and other taxa were identified. The diurnal periodicities recorded for different types were classified into night-time, post dawn, middle day and double maxima (showing two peaks in a day) patterns. In general, no significant correlation between the total air spora and the meteorological parameters could be established. It is evident that the local cropping practices may have some regulating role on spore concentration in the air of the study area.     

Prediction of in vivo radiation dose status in radiotherapy patients using ex vivo and in vivo gene expression signatures

After a large-scale nuclear accident or an attack with an improvised nuclear device, rapid biodosimetry would be needed for triage. As a possible means to address this need, we previously defined a gene expression signature in human peripheral white blood cells irradiated ex vivo that predicts the level of radiation exposure with high accuracy. We now demonstrate this principle in vivo using blood from patients receiving total-body irradiation (TBI). Whole genome microarray analysis has identified genes responding significantly to in vivo radiation exposure in peripheral blood. A 3-nearest neighbor classifier built from the TBI patient data correctly predicted samples as exposed to 0, 1.25 or 3.75 Gy with 94% accuracy (P < 0.001) even when samples from healthy donor controls were included. The same samples were classified with 98% accuracy using a signature previously defined from ex vivo irradiation data. The samples could also be classified as exposed or not exposed with 100% accuracy. The demonstration that ex vivo irradiation is an appropriate model that can provide meaningful prediction of in vivo exposure levels, and that the signatures are robust across diverse disease states and independent sample sets, is an important advance in the application of gene expression for biodosimetry.     

Low-shear-modeled microgravity-grown Penicillium chrysogenum -mediated biosynthesis of silver nanoparticles with enhanced antimicrobial activity and its anticancer effect in human liver cancer and fibroblast cells

Gravitational force and shear forces induce various changes in gene expression and metabolite production of microorganisms. Previous reports have shown that there are differences in the expression of different sets of proteins and enzymes under microgravity conditions compared to normal gravity. The aim of this study is to utilize culture filtrates of Penicillium chrysogenum grown under microgravity and normal conditions to synthesize silver nanoparticles and to examine whether there is any difference between their physiochemical and biological function. Synthesized nanoparticles were characterized using UV–Vis spectroscopy, FTIR, XRD, and TEM. Biological functional studies such as antimicrobial activity, cytotoxic studies, and anticancer activity were carried out. Antimicrobial activity was tested using antibiotic susceptibility testing by Kirby–Bauer method and cytotoxicity tests were carried out using 3T3-L1 normal fibroblasts cells and Hep-G2 cancer cell lines. Interestingly, our results indicated that microgravity-synthesized silver nanoparticles possess enhanced antibacterial activity and cytotoxic effect against cancer cells compared to normal gravity-synthesized silver nanoparticle. This work highlighted the importance of gravitational vector on the fungal enzyme profiles and their role in silver nanoparticle synthesis with enhanced biological activity.     

ArgR and PepA, accessory proteins for XerCD-mediated resolution of ColE1 dimers, are also required for stable maintenance of the P1 prophage

Dimers of low copy number plasmids must be resolved to monomers to prevent interference with active partition. For the P1 prophage this is achieved by the Cre site-specific recombinase acting at lox. Multimerisation of multicopy plasmids threatens stability via copy number depression, and multimers of ColE1 are resolved by XerCD-mediated recombination at cer. Xer-cer is constrained to multimer resolution by accessory proteins ArgR and PepA. Recently, it has been shown that ArgR and PepA influence Cre-mediated recombination at a cer-lox hybrid site in vitro, defining the structure of the synaptic complex. We show here that both ArgR and PepA are required for stable maintenance of the P1 prophage. It is extremely difficult to establish P1 in a strain lacking PepA and the prophage was lost rapidly once selection was removed. ArgR plays a less crucial role although its absence significantly increased prophage loss. The effect of the accessory proteins is seen only at physiological concentrations of Cre; when the recombinase is expressed from a multicopy plasmid, the prophage is unstable even in the presence of ArgR and PepA. We propose that ArgR and PepA are involved in Cre-lox recombination in vivo, probably by constraining the system to resolution of prophage dimers.     

Comparative aerobiology,allergenicity and biochemistry of three palm pollen grains in Calcutta,India

A Burkard volumetric trap was used at Salt Lake City, Calcutta, to record the occurrence and frequency of three common palm pollen, namely,Areca catechu, Borassus flabellifer andPhoenix sylvestris for two consecutive years (July 1988–June 1990). The meteorological factors responsible for the frequency of relevant airborne pollen grains were analysed. The allergenic potential of these pollen types was investigated by skin-prick tests on adult respiratory allergic patients. These were also chemically analysed in terms of total carbohydrate, lipid and soluble protein. Total soluble protein of the above types was used in 11% SDS-polyacrylamide gel electrophoresis to study the range of molecular components.     

Interaction of silver and gold nanoparticles in mammalian cancer: as real topical bullet for wound healing— A comparative study

The present study evaluates in vitro cytotoxic effects and the mode of interaction of biologically synthesized Ag and Au nanoparticles (NPs) using Brassica oleracea L. var. capitata f. rubra (BOL) against HT-1080 cancer cells and bacterial cells as well as their wound healing efficacy using a mouse model. UV–visible spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, and energy-dispersive X-ray analysis have ascertained the formation of nano-sized Ag and Au particles. Fourier transform infrared analysis has confirmed that polyphenol and amide groups in BOL act as capping as well as reducing agents. The free radical scavenging activity under in vitro conditions is found to be higher for the Ag NPs when compared to the Au NPs. Acridine orange–ethidium bromide dual staining and comet assay have indicated that the cytotoxic effects are mediated through nuclear morphological changes and DNA damage. The intracellular localization of Ag and Au NPs in HT-1080 cells and their subsequent effect on apoptosis and necrosis were analyzed by flow cytometry while the mode of interaction was established by scanning electron microscopy under field emission mode and by bio-transmission electron microscopy. These methods of analysis clearly revealed that the Ag and Au NPs have easily entered and accumulated into the cytosol and nucleus, resulting in activation of inflammatory and apoptosis pathways, which in turn cause damage in DNA. Further, mRNA and protein expression of caspase-3 and caspase-7, TNF-α, and NF-κB have provided sufficient clues for induction of intrinsic and extrinsic apoptosis and inflammatory pathways in Ag NP- and Au NP-treated cells. Evaluation of wound healing properties of Ag and Au NPs using a mouse model indicates rapid healing of wounds. In addition, no clear toxic effects and no nuclear abnormalities in peripheral blood cells are observed. Ag NPs appear to be a better anticancer therapeutic agent than Au NPs. Nonetheless, both Ag NPs and Au NPs show potential for promoting topical wound healing without any toxic effects.

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Graphical abstract Schematic representation of biological synthesis of Ag and Au NPs and its application on cancer and wound healing: