Metal‐Oxide‐Free Methylammonium Lead Iodide Perovskite‐Based Solar Cells: the Influence of Organic Charge Transport Layers

Metal‐oxide‐free methylammonium lead iodide perovskite‐based solar cells are prepared using a dual‐source thermal evaporation method. This method leads to high quality reproducible films with large crystal domain sizes allowing for an in depth study of the effect of perovskite film thickness and the nature of the electron and hole blocking layers on the device performance. The power conversion efficiency increases from 4.7% for a device with only an organic electron blocking layer to almost 15% when an organic hole blocking layer is also employed. In addition to the in depth study on small area cells, larger area cells (approx. 1 cm^?2) are prepared and exhibit efficiencies in excess of 10%.     

Molecular sieves provoke multiple substitutions in the enzymatic synthesis of fructose oligosaccharide–lauryl esters

The cause of discrepancies in the literature regarding the specificity of immobilized Candida antarctica lipase B in the acylation of oligosaccharides was examined. Molecular sieves, generally used to control the water content during acylation reactions, turned out to have an important role in this. It was proven that molecular sieves alone can catalyze the acylation of fructose oligomers using vinyl laurate, leading to multiple substitution of the oligomers. This effect was the most profound at conditions unfavorable for the enzyme, because this resulted in a relatively high concentration of the chemically produced adducts. The enzyme alone catalyzed the formation of monosubstituted oligomers. It was proven that even solvent pre-drying by molecular sieves already causes the release of catalyzing compounds to the liquid, leading to subsequent catalysis. These findings should be taken into account when applying molecular sieves in this type of reactions in the future. Molecular sieves could, moreover, be used as a catalyst when multiple substitution is desired.     

Cotransformation of Aspergillus nidulans: a tool for replacing fungal genes

Summary When a non-selected DNA sequence was added during the transformation of amdS320 deletion strains of Aspergillus nidulans with a vector containing the wild-type amdS gene the AmdS⁺ transformants were cotransformed at a high frequency. Cotransformation of an amdS320, trpC801 double mutant strain showed that both the molar ratio of the two vectors and the concentration of the cotransforming vector affected the cotransformation frequency. The maximum frequency obtained was defined by the gene chosen as selection marker for transformation. Cotransformation was used to induce a gene replacement in A. nidulans. An amdS320 strain was transformed to AmdS⁺ and cotransformed with a DNA fragment containing a fusion between a non-functional A. nidulans trpC gene and the Escherichia coli lacZ gene. Ten AmdS⁺, LacZ⁺ transformants with a Trp^– mutant phenotype were selected. All of these strains could be transformed with a functional copy of the A. nidulans trpC gene, but only two strains yielded TrpC⁺ transformants which, with a low frequency, had a LacZ^– phenotype. These latter transformants had also lost the AmdS⁺ phenotype. Southern blotting analysis of DNA from these transformants confirmed the inactivation of the wild-type trpC gene, but revealed that amdS vector sequences were also involved in the gene replacement events.     

<Emphasis Type="Italic">Vernonia bayensis</Emphasis> (Asteraceae/Compositae), a new species from Somalia and a key to the Somali species of <Emphasis Type="Italic">Vernonia</Emphasis>

The new species Vernonia bayensis Thulin & Beentje from southern Somalia is described and illustrated, and a new key to the Somali species of the genus is presented.     

Frequency of a natural truncated allele of <Emphasis Type="Italic">MdMLO19</Emphasis> in the germplasm of <Emphasis Type="Italic">Malus domestica</Emphasis>

Podosphaera leucotricha is the causal agent of powdery mildew (PM) in apple. To reduce the amount of fungicides required to control this pathogen, the development of resistant apple cultivars should become a priority. Resistance to PM was achieved in various crops by knocking out specific members of the MLO gene family that are responsible for PM susceptibility (S-genes). In apple, the knockdown of MdMLO19 resulted in PM resistance. However, since gene silencing technologies such as RNAi are perceived unfavorably in Europe, a different approach that exploits this type of resistance is needed. This work evaluates the presence of non-functional naturally occurring alleles of MdMLO19 in apple germplasm. The screening of the re-sequencing data of 63 apple individuals led to the identification of 627 single nucleotide polymorphisms (SNPs) in five MLO genes (MdMLO5, MdMLO7, MdMLO11, MdMLO18, and MdMLO19), 127 of which were located in exons. The T-1201 insertion of a single nucleotide in MdMLO19 caused the formation of an early stop codon, resulting in a truncated protein lacking 185 amino acids, including the calmodulin-binding domain. The presence of the insertion was evaluated in 115 individuals. It was heterozygous in 64 and homozygous in 25. Twelve of the 25 individuals carrying the insertion in homozygosity were susceptible to PM. After barley, pea, cucumber, and tomato, apple would be the fifth species for which a natural non-functional mlo allele has been found.     

Validation of the TracmorD Triaxial Accelerometer to Assess Physical Activity in Preschool Children

Objectives: To assess validity evidence of Tracmor_D to determine energy used for physical activity in 3‐4‐year‐old children. Design and Methods: Participants were randomly selected from GECKO Drenthe cohort (n = 30, age 3.4 ± 0.3 years). Total energy expenditure (TEE) was measured using the doubly labeled water method. Sleeping metabolic rate (SMR) was measured by indirect calorimetry (Deltatrac). TEE and SMR were used to calculate physical activity level (PAL) and activity energy expenditure (AEE). Physical activity was monitored using a DirectLife triaxial accelerometer, Tracmor_D with activity counts per minute (ACM) and activity counts per day (ACD) as outcome measures. Results: The best predictor for PAL was ACM with gender and weight, the best predictor for AEE was ACM alone (backward regression, R² = 0.50, P = 0.010 and R² = 0.31, P = 0.011, respectively). With ACD, the prediction model for PAL included ACD, height, gender, and sleep duration (R² = 0.48, P = 0.033), the prediction model for AEE included ACD, gender and sleep duration (R² = 0.39, P = 0.042). The accelerometer was worn for 5 days, but 3 days did not give a different estimated PAL. Conclusion: Tracmor_D provides moderate‐to‐strong validity evidence that supports its use to evaluate energy used for physical activity in 3‐4‐year‐old children.     

Complex genetics controls natural variation among seed quality phenotypes in a recombinant inbred population of an interspecific cross between Solanum lycopersicum × Solanum pimpinellifolium

Seed quality in tomato is associated with many complex physiological and genetic traits. While plant processes are frequently controlled by the action of small‐ to large‐effect genes that follow classic Mendelian inheritance, our study suggests that seed quality is primarily quantitative and genetically complex. Using a recombinant inbred line population of Solanum lycopersicum × Solanum pimpinellifolium, we identified quantitative trait loci (QTLs) influencing seed quality phenotypes under non‐stress, as well as salt, osmotic, cold, high‐temperature and oxidative stress conditions. In total, 42 seed quality traits were analysed and 120 QTLs were identified for germination traits under different conditions. Significant phenotypic correlations were observed between germination traits under optimal conditions, as well as under different stress conditions. In conclusion, one or more QTLs were identified for each trait with some of these QTLs co‐locating. Co‐location of QTLs for different traits can be an indication that a locus has pleiotropic effects on multiple traits due to a common mechanistic basis. However, several QTLs also dissected seed quality in its separate components, suggesting different physiological mechanisms and signalling pathways for different seed quality attributes.     

Influence of different combinations of bacteria and yeasts in voice prosthesis biofilms on air flow resistance

Laryngectomized patients use silicone rubber voice prostheses to rehabilitate their voice. However, biofilm formation limits the lifetime of voice prostheses. The presence of particular combinations of bacterial and yeast strains in voice prosthesis biofilms has been suggested to be crucial for causing valve failure. In order to identify combinations of bacterial and yeast strains causative to failure of voice prostheses, the effects of various combinations of bacterial and yeast strains on air flow resistances of Groningen button voice prostheses were determined. Biofilms were grown on Groningen button voice prostheses by inoculating so-called artificial throats with various combinations of clinically relevant bacterial and yeast strains. After 3 days, all throats were perfused three times daily with 250 ml phosphate buffered saline and at the end of each day the artificial throats were filled with growth medium for half an hour. After 7 days, the air flow resistances of the prostheses were measured. These air flow resistances were expressed relative to the air flow resistances of the same prostheses prior to biofilm formation. This study shows that biofilms causing strong increases in air flow resistance (26 to 28 cm water.s/l) comprised combinations of microorganisms, involving Candida tropicalis, Staphylococcus aureus and Rothia dentocariosa. This revised version was published online in June 2006 with corrections to the Cover Date.     

Local accumulations of B-50/GAP-43 evoke excessive bleb formation in PC12 cells

B-50 (GAP-43) is an axonal, plasma membrane-associated protein involved in growth cone morphology and function. We have conducted immunocytochemical, electron microscopic, and time-lapse experiments to visualize morphological consequences of local accumulations of B-50 at the plasma membrane of B-50-transfected PC-B2 cells, a clonal PC12 cell line with very low expression of endogenous B-50. The distribution of the transfected B-50 within these cells was inhomogeneous. At sites where the B-50 concentration was locally increased up to twofold, numerous filopodia were present in growth cone-like, substrate-attached regions. When local B-50 concentrations were even higher (up to 6.2-fold), blebs were formed, often containing vesicular structures, heavily decorated with B-50 immunoreactivity. Double labeling with f-actin binding phalloidin revealed that local B-50 accumulations were accompanied by increased actin filament concentrations. Colocalization of B-50 with actin filaments was prominent in filopodia, but was virtually absent in blebs, suggesting a disconnection of the bleb plasma membrane from the actin cytoskeleton. We conclude that B-50 evokes distinct effects on cell-surface activity in PC12 cells depending on its local concentration.