Spatial Charge Separation as the Origin of Anomalous Stark Effect in Fluorous 2D Hybrid Perovskites

2D hybrid perovskites (2DP) are versatile materials, whose electronic and optical properties can be tuned through the nature of the organic cations (even when those are seemingly electronically inert). Here, it is demonstrated that fluorination of the organic ligands yields glassy 2DP materials featuring long‐lived correlated electron–hole pairs. Such states have a marked charge‐transfer character, as revealed by the persistent Stark effect in the form of a second derivative in electroabsorption. Modeling shows that electrostatic effects associated with fluorination, combined with the steric hindrance due to the bulky side groups, drive the formation of spatially dislocated charge pairs with reduced recombination rates. This work enriches and broadens the current knowledge of the photophysics of 2DP, which will hopefully guide synthesis efforts toward novel materials with improved functionalities.     

Nanomotion Detection Method for Testing Antibiotic Resistance and Susceptibility of Slow‐Growing Bacteria

Infectious diseases are caused by pathogenic microorganisms and are often severe. Time to fully characterize an infectious agent after sampling and to find the right antibiotic and dose are important factors in the overall success of a patient's treatment. Previous results suggest that a nanomotion detection method could be a convenient tool for reducing antibiotic sensitivity characterization time to several hours. Here, the application of the method for slow‐growing bacteria is demonstrated, taking Bordetella pertussis strains as a model. A low‐cost nanomotion device is able to characterize B. pertussis sensitivity against specific antibiotics within several hours, instead of days, as it is still the case with conventional growth‐based techniques. It can discriminate between resistant and susceptible B. pertussis strains, based on the changes of the sensor's signal before and after the antibiotic addition. Furthermore, minimum inhibitory and bactericidal concentrations of clinically applied antibiotics are compared using both techniques and the suggested similarity is discussed.     

Image and video denoising by combining unsupervised bounded generalized gaussian mixture modeling and spatial information

Multimedia Tools and Applications - In recent years, a great deal of effort has been expended on developing robust solutions for images quality degradation caused mainly by noise. In this paper, we...     

Adolescents' and mothers' perceptions of the cognitive and relational functions of collaboration and adjustment in dealing with type 1 diabetes.

We examined how adolescents' and mothers' perceptions of cognitive and interpersonal functions of collaboration surrounding Type 1 diabetes differed and how they related to adolescent age, psychosocial, and diabetes adjustment. Adolescents (M = 14.16 years) and mothers completed questionnaires assessing the functions of collaboration for the adolescent, quality of the mother-adolescent relationship, emotional adjustment, and adherence to the diabetes regimen. Confirmatory factor analysis (CFA) of perceptions of collaboration confirmed three dimensions: collaboration to compensate for cognitive function, interpersonal enjoyment, and frequency of collaboration. Although adolescents' and mothers' views of interpersonal enjoyment and frequency of collaboration converged, their perceptions of compensation were unrelated. Mothers' perceptions of adolescents' compensation were unrelated to perceptions of enjoyment and frequency. Both adolescents and mothers perceived less compensation and less enjoyment of collaboration with increasing adolescent age, but only adolescents reported collaborating less frequently with higher age. Better emotional adjustment and adherence occurred when mothers and adolescents perceived enjoying collaboration (controlling for mothers' acceptance) regardless of age. Enjoying collaboration at an interpersonal level may be an important avenue for successful diabetes management during adolescence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genomic structure,cloning and expression of two phospholipase D isoenzymes from white cabbage

Phospholipase D (PLD) from cabbage is interesting as biocatalyst in phospholipid transformation. To provide the basis for genetic engineering of the enzyme, gene cloning and sequencing were carried out. We have recently identified two isoenzymes, PLD1 and PLD2, on the basis of their cDNAs, here we describe their genomic structure consisting of 3404 and 3614 bp, respectively. Based on their sequence, PLD1 and PLD2 can be assigned to the α‐type of plant PLDs, they contain two HKD motifs and the C2 domain with a phosphatidylinositol 4,5‐bisphosphate (PIP₂) binding motif. Starting from pld1 cDNA, expression studies were carried out. Whereas expression using constructs with StrepTactin or Glutathion S‐transferase tags was not successful, soluble active enzyme was produced from constructs without tag. pld2 was expressed accordingly. Both enzymes were purified by Ca²⁺‐mediated hydrophobic interaction chromatography to high purity. N‐terminal sequencing of PLD1 and PLD2 revealed that the Met‐free N‐termini of both enzymes correspond to sequences derived from the coding region of the pld1 and pld2 genes, respectively. Both recombinant enzymes showed highest hydrolytic activities at pH 5.5 to 5.6, independent of Ca²⁺ concentration (10—100 mM). The optimum Ca²⁺ concentration was 45 mM for PLD1 and PLD2. Both enzymes showed comparable activities in hydrolysis and transphosphatidylation of phospholipids.     

Aedes aegypti Piwi4 Structural Features Are Necessary for RNA Binding and Nuclear Localization

The PIWI-interacting RNA (piRNA) pathway provides an RNA interference (RNAi) mechanism known from Drosophila studies to maintain the integrity of the germline genome by silencing transposable elements (TE). Aedes aegypti mosquitoes, which are the key vectors of several arthropod-borne viruses, exhibit an expanded repertoire of Piwi proteins involved in the piRNA pathway, suggesting functional divergence. Here, we investigate RNA-binding dynamics and subcellular localization of A. aegypti Piwi4 (AePiwi4), a Piwi protein involved in antiviral immunity and embryonic development, to better understand its function. We found that AePiwi4 PAZ (Piwi/Argonaute/Zwille), the domain that binds the 3′ ends of piRNAs, bound to mature (3′ 2′ O-methylated) and unmethylated RNAs with similar micromolar affinities (K_D = 1.7 ± 0.8 μM and K_D of 5.0 ± 2.2 μM, respectively; p = 0.05) in a sequence independent manner. Through site-directed mutagenesis studies, we identified highly conserved residues involved in RNA binding and found that subtle changes in the amino acids flanking the binding pocket across PAZ proteins have significant impacts on binding behaviors, likely by impacting the protein secondary structure. We also analyzed AePiwi4 subcellular localization in mosquito tissues. We found that the protein is both cytoplasmic and nuclear, and we identified an AePiwi4 nuclear localization signal (NLS) in the N-terminal region of the protein. Taken together, these studies provide insights on the dynamic role of AePiwi4 in RNAi and pave the way for future studies aimed at understanding Piwi interactions with diverse RNA populations.     

Aflatoxin B1, ochratoxin A and zearalenone in sorghum grains marketed in Tunisia

A total of 64 samples of sorghum (37 Tunisian sorghum samples and 27 Egyptian sorghum samples) were collected during 2011–2012 from markets in Tunisia. Samples were analysed for contamination with aflatoxin B1, ochratoxin A and zearalenone by High-Performance Liquid Chromatography Coupled with Fluorescence Detection (HPLC-FLD). Aflatoxin B1 was found in 38 samples in the range 0.03–31.7 µg kg^?1. Ochratoxin A was detected in 24 samples with concentrations ranging from 1.04 to 27.8 µg kg^?1. Zearalenone was detected in 21 samples and the concentration varied between 3.7 and 64.5 µg kg^?1. ANOVA analysis of the influence of the country of origin on the incidence and concentration of mycotoxins in the samples studied showed no significant difference (P > 0.05) between the two batches of samples for each of the three mycotoxins studied. The studied mycotoxins contaminate sorghum and may also co-exist because of the diversity of the mycobiota in this cereal.