Inverted Tandem Polymer Solar Cells with Polyethylenimine‐Modified MoOX/Al2O3:ZnO Nanolaminate as the Charge Recombination Layers

A new charge recombination layer for inverted tandem polymer solar cells is reported. A bilayer of MoO_X/Al₂O₃:ZnO nanolaminate is shown to enable efficient charge recombination in inverted tandem cells. A polymer surface modification on the MoO_X/Al₂O₃:ZnO nanolaminate bilayer increases the work function contrast between the two outward surfaces of the charge recombination layer, further improving the performance of tandem solar cells. An analysis of the electrical, optical, and surface properties of the charge recombination layer is presented. Inverted tandem polymer solar cells, with two photoactive layers comprising poly (3‐hexylthiophene) (P3HT):indene‐C₆₀ bisadduct (IC₆₀BA) for the bottom cell and poly[(4,8‐bis‐(2‐ethylhexyloxy)‐benzo[1,2‐b:4,5‐b']dithiophene)‐2,6‐diyl‐alt‐(4‐(2‐ethylhexanoyl)‐thieno[3,4‐b]thiophene))‐2,6‐diyl] (PBDTTT‐C):[6,6]‐phenyl C₆₁ butyric acid methyl ester (PC₆₀BM) for the top cell, yield an open‐circuit voltage of 1481 mV ± 15 mV, a short‐circuit current density of 7.1 mA cm^?2 ± 0.1 mA cm^?2, and a fill factor of 0.62 ± 0.01, resulting in a power conversion efficiency of 6.5% ± 0.1% under simulated AM 1.5G, 100 mW cm^?2 illumination.     

Assessing age,breeding stage,and mating activity as drivers of variation in the reproductive microbiome of female tree swallows

Sexually transmitted microbes are hypothesized to influence the evolution of reproductive strategies. Though frequently discussed in this context, our understanding of the reproductive microbiome is quite nascent. Indeed, testing this hypothesis first requires establishing a baseline understanding of the temporal dynamics of the reproductive microbiome and of how individual variation in reproductive behavior and age influence the assembly and maintenance of the reproductive microbiome as a whole. Here, we ask how mating activity, breeding stage, and age influence the reproductive microbiome. We use observational and experimental approaches to explain variation in the cloacal microbiome of free‐living, female tree swallows (Tachycineta bicolor). Using microsatellite‐based parentage analyses, we determined the number of sires per brood (a proxy for female mating activity). We experimentally increased female sexual activity by administering exogenous 17ß‐estradiol. Lastly, we used bacterial 16S rRNA amplicon sequencing to characterize the cloacal microbiome. Neither the number of sires per brood nor the increased sexual activity of females significantly influenced female cloacal microbiome richness or community structure. Female age, however, was positively correlated with cloacal microbiome richness and influenced overall community structure. A hypothesis to explain these patterns is that the effect of sexual activity and the number of mates on variation in the cloacal microbiome manifests over an individual''s lifetime. Additionally, we found that cloacal microbiome alpha diversity (Shannon Index, Faith''s phylogenetic distance) decreased and community structure shifted between breeding stages. This is one of few studies to document within‐individual changes and age‐related differences in the cloacal microbiome across successive breeding stages. More broadly, our results contribute to our understanding of the role that host life history and behavior play in shaping the cloacal microbiomes of wild birds.     

Fabrication and Characterization of Native and Oxidized Potato Starch Biodegradable Films

The need to replace conventional polymers due to environmental pollution caused by them has led to increased production of biodegradable polymers such as starch. Thus, the application possibilities of starch have increased. In this study, we produced and characterized biodegradable films derived from native and oxidized potato starch. The film-forming solution was prepared with different concentrations of extracted starch (native or oxidized) and a plasticizer (glycerol or sorbitol). Then, the mechanical, barrier, morphological, and structural properties of the films were characterized. The moisture content of the films varied from 15.35?±?1.31 to 21.78?±?0.49%. The elastic modulus of the films ranged from 219?±?14.97 to 2299?±?62.91 MPa. The film of oxidized starch plasticized with sorbitol in the lowest content was the most resistant and flexible; moreover, this film also presented lower water vapor permeability and low solubility in water. Fourier-transform infrared spectroscopic analysis of the biodegradable films indicated the presence of same functional groups as those of starch with bands in the same regions. The film thickness was lower for the films plasticized with glycerol whereas the color variation (Δ?) was lower for the ones plasticized with sorbitol. In case of both plasticizers, the increase in their content decreased the Δ? value. All the biodegradable films presented stability against water absorption owing to their low solubility in water. Morphological evaluation revealed the presence of partially gelatinized starch granules in the films. The roughness parameter (Rq) of the films varied from 3.39 to 10.9 nm, indicating that their surfaces are smooth. X-ray diffraction studies showed a B-type pattern for the starches, which is representative of tubers. Further, the films present higher relative crystallinity (RC) compared to the starches. The biodegradable starch films are uniform, transparent and with low solubility in water. The oxidation of starch and use of sorbitol as a plasticizer resulted in improved properties of the starch films, which is suitable for application.     

First Report of Botrytis cinerea Pers. on Salicornia bigelovii Torr. in North‐West México

Grey mould has been detected on Salicornia bigelovii Torr plants in nursery and in the wild in north‐west Mexico. Sampling of the grey mould was performed in the state of Sonora, Mexico, of wild as well as cultivated S. bigelovii plants. The samples were isolated, and based on morphology, the species was identified as Botrytis cinerea Pers. Koch's postulates were fulfilled by pathogenicity tests carried out in plated petri dishes on branches from the 3‐month‐old potted S. bigelovii plants. To our knowledge, this is the first report of the isolation and identification of the fungal pathogen B. cinerea from S. bigelovii in the north‐west Mexico.     

Escherichia coli ppGpp synthetase II activity requires spoT

Escherichia coli has two enzymes catalyzing the synthesis of guanosine tetraphosphate (ppGpp), designated ppGpp synthetase I (PSI = RelA) and II (PSII), whose activities are regulated differently. Until now, the gene for PSII had not been identified. Here, an E. coli relA1 strain that expresses lacZ from an rrnB P1 promoter was used to screen mutants with increased beta-galactosidase activity on 5-bromo-4-chloro-3-indoyl beta-D-galactoside indicator plates at 30 degrees C. About 15% of the mutants obtained in this manner had reduced levels of ppGpp at 30 degrees C and no detectable ppGpp at 43 degrees C. These mutants did not form colonies at 42 degrees C on minimal medium plates and had elevated ribosome concentrations and higher growth rates at 30 degrees C. Genetic mapping by phage P1 transduction and complementation analyses showed that the mutations were located in spoT and that they were recessive. Specific inhibition of SpoT-dependent ppGpp degradation activity with picolinic acid showed that two of the mutants tested were deficient in ppGpp synthesis activity. These results indicate that spoT is required for PSII activity, suggesting that spoT encodes both ppGpp degradation and synthesis activities and that these two functions can be affected independently by mutation.     

Évaluation de la toxicité deBacillus thuringiensis surSpodoptera frugiperda

Résumé Cinquante deux souches deB. thuringiensis appartenant à 13 sérovars ont été testées sur des chenilles néonates deSpodoptera frugiperda en contaminant la surface du milieu semi-synthétique d'élevage. Deux souches du sérovarkenyae et une autre du sérovartolworthi provoquent le plus de mortalité, suivies par les souches des sérovarsaizawai etkurstaki. Les souches les moins actives appartiennent aux sérotypesalesti, dendrolimus, sotto etcolmeri. L'action des souches sur le développement larvaire a aussi été abordée. Les souches des sérovarskenyae, aizawai etkurstaki ont ralenti le développement des chenilles, tandis que les souches des sérovarsalesti, sotto etcolmeri n'ont eu aucun effet.      

Qualitative simulation of the initiation of sporulation in <Emphasis Type="Italic">Bacillus subtilis</Emphasis>

Under conditions of nutrient deprivation, the Gram positive soil bacterium Bacillus subtilis can abandon vegetative growth and form a dormant, environmentally-resistant spore instead. The decision to either divide or sporulate is controlled by a large and complex genetic regulatory network integrating various environmental, cell-cycle, and metabolic signals. Although sporulation in B. subtilis is one of the best-understood model systems for prokaryotic development, very little quantitative data on kinetic parameters and molecular concentrations are available. A qualitative simulation method is used to model the sporulation network and simulate the response of the cell to nutrient deprivation. Using this method, we have been able to reproduce essential features of the choice between vegetative growth and sporulation, in particular the role played by competing positive and negative feedback loops.     

Brain blotting: a method to detect multiple DNA copies in specific brain regions

We developed a method to detect multiple DNA copies (both cellular and viral) in specific brain regions by blotting thick frozen sections onto nylon membranes. This was achieved by "printing" the frozen sections on standard blotting paper immediately after cryotome sectioning and performing blotting according to the standard Southern technique. A "replica" of the blotted section was obtained by keeping on the glass slide the next frozen section cut, which was then stained for conventional histopathological analysis and the cell nuclei counted to give an estimate of the total amount of DNA present in each section. The blotted membranes were then denatured and hybridized with a nick-translated Alu probe either at 42 degrees C with 50% formamide or at 68 degrees C without formamide. Brain sections from mice infected with Herpes simplex virus 1 (HSV1), blotted and hybridized with a nick-translated HSV1 probe, clearly showed the focal nature of the Herpes simplex infection, which was also demonstrated immunohistologically using a virus specific antiserum. This method of DNA detection, conveniently modified, might also be used to detect nuclear and cytoplasmic RNAs in specific coronal sections of whole brain before localization at high power by standard in situ techniques.