Impact of Blend Morphology on Interface State Recombination in Bulk Heterojunction Organic Solar Cells

This work is a reinvestigation of the impact of blend morphology and thermal annealing on the electrical performance of regioregular‐P3HT:PC₆₀BM bulk heterojunction organic solar cells. The morphological, structural, and electrical properties of the blend are experimentally investigated with atomic force microscopy, X‐ray diffraction, and time‐of‐flight measurements. Current–voltage characteristics of photodiode devices are measured in the dark and under illumination. Finally, the existence of exponential electronic band tails due to gap states is experimentally confirmed by measuring the device spectral response in the subband gap regime. This method reveals the existence of a large density of gap states, which is partially and systematically reduced by thermal annealing. When the band tails are properly accounted for in the drift and diffusion simulations, experimentally measured charge transport characteristics, under both dark and illuminated conditions and as a function of annealing time, can be satisfactorily reproduced. This work further confirms the critical impact of tails states on the performance of solar cells.     

Photoluminescence of hydrophilic silicon nanocrystals in aqueous solutions

Stable aqueous solutions of undecylenic-acid-grafted silicon nanocrystals (Si-nc) were prepared. The time evolution of the photoluminescence properties of these hydrophilic silicon nanocrystals has been followed on different timescales (hours and days). On a short timescale (hours), Si-nc tend to agglomerate while the PL lineshape and intensity are stable. Agglomeration can be reduced by using suitable surfactants. On a long timescale (days), oxidation of Si-nc occurs even in the presence of surfactants. These two observations render Si-nc very useful as a labeling agent for biosensing.     

Enhancement of optical processes in coupled plasmonic nanocavities [Invited

We present detailed experimental and numerical investigations of resonances in deep nanogroove gratings in metallic substrates. These plasmonic nanocavity gratings feature enhanced fields within the grooves that enable a large enhancement of linear and nonlinear optical processes. This enhancement relies on both localized and propagating surface plasmons on the nanopatterned surface. We show that the efficiency of optical processes such as Raman scattering and four-wave mixing is dramatically enhanced by plasmonic nanocavity gratings.     

Isolation and characterization of a psychrotolerant toxin producer, Bacillus weihenstephanensis, in liquid egg products

A psychrotolerant bacteria of the Bacillus cereus group was found responsible for the spoilage of whole liquid egg products. By sequencing a 16S rRNA region and performing a PCR amplification of specific 16S rRNA and cspA signatures, a Bacillus weihenstephanensis was identified. Characterization of this strain shows its ability to grow in defined medium as well as in whole liquid egg at refrigerated temperatures. The strain isolated possesses genes encoding for hemolysin BL, nonhemolytic enterotoxin, and B. cereus enterotoxins and produces enterotoxins with cytotoxic activity in whole liquid egg, even at refrigerated temperatures. The isolate exhibits a clear ability to stick and form biofilms on stainless steel, the most common material used in egg breaking factories, as well as on model hydrophilic (glass) and hydrophobic (polytetrafluoroethylene) materials. These findings show the necessity to monitor for Bacillus contamination in egg products that are often used in the composition of particularly susceptible finished products such as cream, dessert, dairy, meat, and seafood.     

Variations in tumour oxygen tension (pO2) during accelerated radiotherapy of head and neck carcinoma

The study was performed to assess the effect of accelerated radiotherapy on oxygenation of primary tumours and metastatic nodes in patients with advanced head and neck tumours. In 14 patients with head and neck tumour, oxygen tension (pO2) was evaluated in normal tissues and tumours (primary tumour or metastatic neck node) before (0 Gy) and after 2 weeks (32 Gy) of accelerated radiotherapy (70 Gy in 3.5 weeks, with three daily fractions). Radiotherapy was combined with carbogen breathing in 5 patients. pO2 was measured using a polarographic technique. For pooled normal tissues, median pO2 was 38 mmHg before treatment and 46 mmHg after 2 weeks. For tumours, very low values (< 2 mmHg) represented 20% of the recorded values before treatment and 10% after 2 weeks. The relative increase in tumour oxygenation was more pronounced for primary tumours (median pO2 12 mmHg before treatment versus 26 mmHg after 2 weeks, P < 0.05) than for metastatic nodes (respectively, 20 and 27 mmHg P = 0.1). For the 5 patients who breathed carbogen during accelerated radiotherapy, the median pO2 was 44 mmHg at 2 weeks, compared with 13.5 mmHg before treatment (P = 0.05). Very low pO2 values, corresponding to tumour hypoxia, were found in the tumours (primary and metastatic neck nodes) prior to accelerated treatment. During the first 2 weeks of accelerated treatment, an increase in median pO2 was found in nine of the 14 tumours, together with a decrease in the frequency of very low values.     

Sequence-dependent activity of the irinotecan-5FU combination in human colon-cancer model HT-29 in vitro and in vivo

Irinotecan, a DNA-topoisomerase-I inhibitor, is active against metastatic colon carcinoma. We investigated the effects of irinotecan and 5FU combinations in human colon-carcinoma cell line HT-29, both in vitro and in vivo. Cytotoxicity of 24-hr exposure was evaluated by SRB technique and the nature of interactions were determined by median-effect analysis. Strong synergism between irinotecan and 5FU was observed after sequential exposure, and only additivity after simultaneous exposure. At 50% level of kill, the mean sums of fractional effects were 0.13 +/- 0.05 and 0.18 +/- 0.02 respectively for the 2 sequential schedules, indicating that the combined amount of the 2 drugs necessary to kill 50% cells was only 0.18 and 0.13 times respectively, as much as would be required if they demonstrated purely additive behavior. In nude-mice xenografts, schedule-dependent toxicity was observed: the schedule in which irinotecan was administered i.v. 6 hours before 5FU was the most toxic. Higher anti-tumoral activity was noted when 20 mg/kg/day of each drug was administered sequentially (a delay of 6 hr between the 2 drugs) to mice over 5 days, in comparison with simultaneous administration. In vivo data confirmed those obtained in vitro in the same human colon-cancer model. These results suggest that irinotecan and 5FU combinations are of clinical interest and that the schedule of administration is a critical parameter for chemotherapeutic efficacy.     

Pseudopeptide TASP inhibitors of HIV entry bind specifically to a 95-kDa cell surface protein

The template assembled synthetic peptide constructs (TASP), pentavalently presenting the tripeptide KPR or RPK, are potent and specific inhibitors of human immunodeficiency virus (HIV) infection by preventing viral entry into permissive cells. Here the 5[KPsi(CH2N)PR]-TASP construct, Psi(CH2N) for reduced peptide bond, was used in studies to demonstrate its specific binding to a 95-kDa cell surface protein ligand. Compared to its nonreduced 5[KPR]-TASP counterpart, the pseudopeptide 5[KPsi(CH2N)PR]-TASP manifested higher affinity to bind to its cell surface ligand, increased activity to inhibit HIV infection, and resistance to degradation when incubated in serum from an HIV-1 seropositive individual. In ligand blotting experiments, the biotin-labeled 5[KPsi(CH2N)PR]-TASP identified a single 95-kDa protein in crude cell extracts. This 95-kDa protein (p95) is expressed on the cell surface since surface iodination of cells resulted in its labeling, and moreover, following incubation of cells with the biotin-labeled 5[KPsi(CH2N)PR]-TASP, the p95.TASP complex was recovered by affinity chromatography using avidin-agarose. All anti-HIV TASP constructs but not their control derivatives affected the binding of biotin-labeled 5[KPsi(CH2N)PR]-TASP to p95, thus emphasizing the specific nature of this binding. Since 5[KPsi(CH2N)PR]-TASP does not interact with HIV-envelope glycoproteins, our results suggest that TASP inhibitors mediate directly or indirectly a block in HIV-mediated membrane fusion process by binding to the cell surface expressed p95.     

A new chemically defined medium for wine lactic acid bacteria

Growth and activity of lactic acid bacteria is crucial for the production and quality of grape wines but studying their metabolism is difficult in wines or complex laboratory media because of the undefined substrate pools. This work presents a new chemically defined medium that meets the fastidious nutritional requirements of wine lactic acid bacteria and yields rapid and strong growth. The new medium is composed of 44 constituents and a precise protocol is provided for its preparation. Maximum specific growth rates and growth yields of the wine strains studied were comparable to those obtained in common laboratory media, and the new medium allows for various modifications, such as changing the medium pH to the wine range, addition of L-malic acid or utilization of different carbon sources while maintaining growth of wine lactic acid bacteria. The medium was successfully tested with 22 wine strains of the genera Oenococcus, Lactobacillus and Pediococcus. It is suggested that this chemically defined medium be considered for the investigation of the nutritional requirements and metabolism of wine lactic acid bacteria.     

Comparison of the relative quantities of aroma compounds found in fresh apricot (Prunus armeniaca) from six different varieties

Summary The volatile components of fresh apricot (Prunus armeniaca) were isolated by vacuum distillation and fractionated on a silica gel column. Analysis by gaschromatography coupled with mass spectrometry led to the identification of 82 compounds, 60 of which were found for the first time in this fruit. Six varieties, cultivated in the south of France were compared for their firmness, acidity, sweetness and for their content of 56 volatile components. Precoce de Tyrinthe was the least aromatic variety, but produced fruits very early in the season. Palsteyn gave acidic but rather aromatic fruits. Moniqui possessed large but perishable fruits with flowery aroma due to the presence of terpenic ketones. Rouge du Roussillon contained all the identified volatile compounds and possessed a pleasant aroma. Polonais contained many C₆-compounds with herbaceous notes and Bergeron was rich in lactones but poor in terpenic alcohols.

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Über die Gehalte an Aromakomponenten von sechs Aprikosensorten (Prunus armeniaca)

Zusammenfassung Die flüchtigen Aromastoffe von Aprikosen (Prunus armeniaca) wurden durch Vakuumdestillation und anschließende chromatographische Vortrennung und Kieselgel isoliert. Mit kombinierter gaschromatographischer Analyse wurden 82 Komponenten, davon 60 zum ersten Mal, identifiziert. Die Gehalte an Zucker, Säuren und 56 Aromakomponenten von 6 französischen Aprikosensorten wurden miteinander verglichen. Die Sorte Precoce de Tyrinthe ist wenig aromatisch aber frühreif, die Sorte Moniqui trägt große Früchte mit einem Blumenaroma von Ketonen, während Rouge du Roussillon viele Komponenten und das angenehmste Aroma besitzt. Die Sorte Polonais zeichnet sich durch den höchsten Gehalt an C₆-Komponenten und ein krautartiges Aroma aus. Die Sorte Bergeron ist reich an Lactonen, jedoch arm an Terpenalkoholen.