Plant regeneration through direct and indirect organogenesis,phyto-molecular profiles,antioxidant properties and swertiamarin production in elicitated cell suspension cultures of Swertia minor (Griseb.) Knobl

Plant Cell, Tissue and Organ Culture (PCTOC) - The present study reports an optimized protocol for high frequency in vitro plant propagation through direct and indirect organogenesis, phytochemical...     

Compositional and Solvent Engineering in Dion–Jacobson 2D Perovskites Boosts Solar Cell Efficiency and Stability

Hybrid halide 2D perovskites deserve special attention because they exhibit superior environmental stability compared with their 3D analogs. The closer interlayer distance discovered in 2D Dion–Jacobson (DJ) type of halide perovskites relative to 2D Ruddlesden–Popper (RP) perovskites implies better carrier charge transport and superior performance in solar cells. Here, the structure and properties of 2D DJ perovskites employing 3‐(aminomethyl)piperidinium (3AMP²⁺) as the spacing cation and a mixture of methylammonium (MA⁺) and formamidinium (FA⁺) cations in the perovskite cages are presented. Using single‐crystal X‐ray crystallography, it is found that the mixed‐cation (3AMP)(MA_0.75FA_0.25)₃Pb₄I₁₃ perovskite has a narrower bandgap, less distorted inorganic framework, and larger Pb? I? Pb angles than the single‐cation (3AMP)(MA)₃Pb₄I₁₃. Furthermore, the (3AMP)(MA_0.75FA_0.25)₃Pb₄I₁₃ films made by a solvent‐engineering method with a small amount of hydriodic acid have a much better film morphology and crystalline quality and more preferred perpendicular orientation. As a result, the (3AMP)(MA_0.75FA_0.25)₃Pb₄I₁₃‐based solar cells exhibit a champion power conversion efficiency of 12.04% with a high fill factor of 81.04% and a 50% average efficiency improvement compared to the pristine (3AMP)(MA)₃Pb₄I₁₃ cells. Most importantly, the 2D DJ 3AMP‐based perovskite films and devices show better air and light stability than the 2D RP butylammonium‐based perovskites and their 3D analogs.     

Further evidence that deltamethrin-impregnated collars protect domestic dogs from sandfly bites

In many foci of zoonotic visceral leishmaniasis (ZVL), domestic dogs are important reservoir hosts of the causative Leishmania parasites transmitted by phlebotomine sandflies (Diptera: Psychodidae). We tested the protective value of impregnated dog collars (20 g plastic containing deltamethrin 800 mg ai) against Phlebotomus papatasi (Scopoli) sandflies in Iran. For each assay, the dog was sedated and caged in a net with 70-100 wild-caught sandflies overnight (23.30-06.30 hours). Dogs wearing the collars were bitten by approximately 80% fewer sandflies than before collars were fitted, i.e. 51% vs. 11% of hungry female flies exposed. Sandfly mortality rates following 20 h exposure to dogs with collars (18%) or without collars (17%) were not significantly different. Effects of collars were tested when dogs had been wearing them for 8 days. A previous trial against the sandfly P. perniciosus Newstead in France, using smaller dogs, showed that effects of such collars were not fully realized until they had been worn for 2 weeks or more; they remained effective for at least 8 months and killed significant proportions of the sandflies exposed. Present results with P. papatasi, confirming that this simple device provides effective protection against sandflies, are considered sufficiently encouraging to justify a community-wide field trial of deltamethrin-impregnated dog collars against ZVL vector sandflies in Iran.     

Surgical removal of duct occluder device under mild hypothermia without cardiopulmonary bypass

Because the use of percutaneous intervention is increasing for the closure of the patent ductus arteriosus, the procedure-related complications are also on rise, with migration of the device being most common. The routine practice is to remove the migrated duct occluder device under cardiopulmonary bypass. Amplatzer duct occluder used in a 4-month-old infant dislodged into the descending thoracic aorta. It was removed by the posterolateral thoracotomy under mild hypothermia through juxtaductal aortotomy between the aortic cross-clamps. The use of cardiopulmonary bypass is thus avoided.     

Mechanistic approach for fabrication of gold nanoparticles by Nitzschia diatom and their antibacterial activity

The problem of chemically synthesized nanoproducts motivated scientific community to explore ecofriendly methods of nanosynthesis. Diatoms belong to a group of aquatic, unicellular, photosynthetic microalgae have been scarcely investigated as a source of reducing and capping agents for nanosynthesis of pesticides and antibiotics. The present study reports a novel ecofriendly method for the fabrication of bioactive gold nanoparticles using locally isolated Nitzschia diatoms. The diatom-fabricated gold nanoparticles show characteristic ruby red colored with sharp absorbance peak at 529 nm. Electron microscopy confirmed irregular shape of gold nanoparticles, with average size of 43 nm and zeta potential of −16.8 mV. The effects of gold nanoparticles on diatom viability were investigated using light and electron microscopy. The mechanistic approach to shed light on how diatoms reacted after exposure to gold metal salt revealed that exposure to gold chloride triggers elevated levels of catalase and peroxidase (12.76 and 14.43 unit/mg protein, respectively) to relieve reactive oxygen species (ROS) stress induced by gold salt exposure. Investigation studies on mechanisms behind Nitzschia-mediated gold nanoparticles fabrication outlined the role of diatom proteins, polysaccharides in reduction, and stabilization of nanoparticles as confirmed by FT-IR analysis. Bioactivity of gold nanoparticles was accessed by coupling them with antibiotics (penicillin and streptomycin), which increased their antibacterial activity compared to individual nanoparticles and antibiotics (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus). Overall, the present novel phyco-nanotechnological approach is a promising tool to be used as sustainable strategy in green nanotechnology as well as to reduce use of antibiotics in microbial control.     

Cytotoxic Helix-Rich Oligomer Formation by Melittin and Pancreatic Polypeptide

Conversion of amyloid fibrils by many peptides/proteins involves cytotoxic helix-rich oligomers. However, their toxicity and biophysical studies remain largely unknown due to their highly dynamic nature. To address this, we chose two helical peptides (melittin, Mel and pancreatic polypeptide, PP) and studied their aggregation and toxicity. Mel converted its random coil structure to oligomeric helical structure upon binding to heparin; however, PP remained as helix after oligomerization. Interestingly, similar to Parkinson’s associated α-synuclein (AS) oligomers, Mel and PP also showed tinctorial properties, higher hydrophobic surface exposure, cellular toxicity and membrane pore formation after oligomerization in the presence of heparin. We suggest that helix-rich oligomers with exposed hydrophobic surface are highly cytotoxic to cells irrespective of their disease association. Moreover as Mel and PP (in the presence of heparin) instantly self-assemble into stable helix-rich amyloidogenic oligomers; they could be represented as models for understanding the biophysical and cytotoxic properties of helix-rich intermediates in detail.     

Effect of Precursor Solution Aging on the Crystallinity and Photovoltaic Performance of Perovskite Solar Cells

Perovskite materials due to their exceptional photophysical properties are beginning to dominate the field of thin‐film optoelectronic devices. However, one of the primary challenges is the processing‐dependent variability in the properties, thus making it imperative to understand the origin of such variations. Here, it is discovered that the precursor solution aging time before it is cast into a thin film, is a subtle but a very important factor that dramatically affects the overall thin‐film formation and crystallinity and therein factors such as grain growth, phase purity, surface uniformity, trap state density, and overall solar cell performance. It is shown that progressive aging of the precursor promotes efficient formation of larger seeds after the fast nucleation of a large density of small seeds. The hot‐casting method then leads to the growth of large grains in uniform thin‐films with excellent crystallinity validated using scanning microscopy images and X‐ray diffraction patterns. The high‐quality films cast from aged solution is ideal for thin‐film photovoltaic device fabrication with reduced shunt current and good charge transport. This observation is a significant step toward achieving highly crystalline thin‐films with reliability in device performance and establishes the subtle but dramatic effect of solution aging before fabricating perovskite thin‐films.     

Yarrowia lipolytica and pollutants: Interactions and applications

Yarrowia lipolytica is a dimorphic, non-pathogenic, ascomycetous yeast species with distinctive physiological features and biochemical characteristics that are significant in environment-related matters. Strains naturally present in soils, sea water, sediments and waste waters have inherent abilities to degrade hydrocarbons such as alkanes (short and medium chain) and aromatic compounds (biphenyl and dibenzofuran). With the application of slow release fertilizers, design of immobilization techniques and development of microbial consortia, scale-up studies and in situ applications have been possible. In general, hydrocarbon uptake in this yeast is mediated by attachment to large droplets (via hydrophobic cell surfaces) or is aided by surfactants and emulsifiers. Subsequently, the internalized hydrocarbons are degraded by relevant enzymes innately present in the yeast. Some wild-type or recombinant strains also detoxify nitroaromatic (2,4,6-trinitrotoluene), halogenated (chlorinated and brominated hydrocarbons) and organophosphate (methyl parathion) compounds. The yeast can tolerate some metals and detoxify them via different biomolecules. The biomass (unmodified, in combination with sludge, magnetically-modified and in the biofilm form) has been employed in the biosorption of hexavalent chromium ions from aqueous solutions. Yeast cells have also been applied in protocols related to nanoparticle synthesis. The treatment of oily and solid wastes with this yeast reduces chemical oxygen demand or value-added products (single cell oil, single cell protein, surfactants, organic acids and polyalcohols) are obtained. On account of all these features, the microorganism has established a place for itself and is of considerable value in environment-related applications.