Tuning of defects in ZnO nanorod arrays used in bulk heterojunction solar cells

With particular focus on bulk heterojunction solar cells incorporating ZnO nanorods, we study how different annealing environments (air or Zn environment) and temperatures impact on the photoluminescence response. Our work gives new insight into the complex defect landscape in ZnO, and it also shows how the different defect types can be manipulated. We have determined the emission wavelengths for the two main defects which make up the visible band, the oxygen vacancy emission wavelength at approximately 530 nm and the zinc vacancy emission wavelength at approximately 630 nm. The precise nature of the defect landscape in the bulk of the nanorods is found to be unimportant to photovoltaic cell performance although the surface structure is more critical. Annealing of the nanorods is optimum at 300°C as this is a sufficiently high temperature to decompose Zn(OH)₂ formed at the surface of the nanorods during electrodeposition and sufficiently low to prevent ITO degradation.     

Phytochemical Composition and in Vitro Analysis of Nopal (O. Ficus-Indica) Cladodes at Different Stages of Maturity

This study aimed to determine the phytochemical profile and nutraceutical properties of nopal cladodes (Opuntia ficus-indica) at different stages of maturity. Medium-age cladodes showed the highest total saponins, phytosterols, and indigestible fiber, as well as the highest in vitro antioxidant capacity and digestive enzymes inhibitory activity. Furthermore, these cladodes presented the highest content of p-hydroxybenzoic acid, p-coumaric acid, rutin, narcissin, nicotiflorin, β-sitosterol, and sitosteryl-3-β-glucopyranoside, as well as several amino acids, organic acids, and fatty acids. Whereas young cladodes contained the highest concentration of condensed and hydrolyzable tannins. These results demonstrated that maturity affects the nutritional and nutraceutical properties of nopal cladodes.     

New high capacity getter for vacuum insulated mobile LH2 storage tank systems

Current “Non-evaporable getters” (NEGs) are important for the improvement of vacuum by the help of metallic surface sorption of residual gas molecules. High porosity alloys or powder mixtures of Zr, Ti, Al, V, Fe and other metals are the base material for this kind of gas sorbents. The development of vacuum technologies creates new challenges for the field of getter materials. The main sorption parameters of the current NEGs, namely, pumping speed and sorption capacity, have reached certain level limits. Chemically active metals are the basis of NEGs of a new generation. The appearance of new materials with high sorption capacity at room temperature is a long-felt need. It is obvious, that chemically active metals and alloys with reactivity higher, than that of transition metals, can become this kind of materials. The potential of active metals as the strongest gas sorbents is very high. The improved getter materials allow faster pumping speed. The sticking rate on the chemically active surface is significantly higher, and sorption capacity can be increased by up to 104 times (during the life-time of a device the entire getter material reacts with residual gases). The main structural form of the new getter concepts are spherical powders, granules and porous multi-layers. The full pumping performance takes already place at room temperature and the activation temperature can be adjusted between room temperature and 660 °C. The successful insertion of this new chemical getter pump in a mobile double-walled LH₂ tank system shows the very high sorption capacity of all relevant residual gases including H₂. This new invention opens the possibility for significant vacuum improvements especially in the field of H₂ pumping, which is an important challenge in many different vacuum devices and processes.     

Automatic on-line monitoring of atmospheric volatile organic compounds: gas chromatography-mass spectrometry and gas chromatography-flame ionization detection as complementary systems

Traditionally air quality networks have been carrying out the continuous, on-line measurement of volatile organic compounds (VOC) in ambient air with GC-FID. In this paper some identification and coelution problems observed while using this technique in long-term measurement campaigns are described. In order to solve these problems a GC-MS was set up and operated simultaneously with a GC-FID for C₂-C₁₁ VOCs measurement.There are few on-line, unattended, long term measurements of atmospheric VOCs performed with GC-MS. In this work such a system has been optimized for that purpose, achieving good repeatability, linearity, and detection limits of the order of the GC-FID ones, even smaller in some cases. VOC quantification has been made by using response factors, which is not frequent in on-line GC-MS. That way, the identification and coelution problems detected in the GC-FID, which may led to reporting erroneous data, could be corrected.The combination of GC-FID and GC-MS as complementary techniques for the measurement of speciated VOCs in ambient air at sub-ppbv levels is proposed. Some results of the measurements are presented, including concentration values for some compounds not found until now on public ambient air VOC databases, which were identified and quantified combining both techniques. Results may also help to correct previously published VOC data with wrongly identified compounds by reprocessing raw chromatographic data.     

Degradable Bottlebrush Polypeptides and the Impact of their Architecture on Cell Uptake,Pharmacokinetics, and Biodistribution In Vivo

Bottlebrush polymers are highly promising as unimolecular nanomedicines due to their unique control over the critical parameters of size, shape and chemical function. However, since they are prepared from biopersistent carbon backbones, most known bottlebrush polymers are non-degradable and thus unsuitable for systemic therapeutic administration. Herein, we report the design and synthesis of novel poly(organo)phosphazene-g-poly(α-glutamate) (PPz-g-PGA) bottlebrush polymers with exceptional control over their structure and molecular dimensions (Dh ≈ 15–50 nm). These single macromolecules show outstanding aqueous solubility, ultra-high multivalency and biodegradability, making them ideal as nanomedicines. While well-established in polymer therapeutics, it has hitherto not been possible to prepare defined single macromolecules of PGA in these nanosized dimensions. A direct correlation was observed between the macromolecular dimensions of the bottlebrush polymers and their intracellular uptake in CT26 colon cancer cells. Furthermore, the bottlebrush macromolecular structure visibly enhanced the pharmacokinetics by reducing renal clearance and extending plasma half-lives. Real-time analysis of the biodistribution dynamics showed architecture-driven organ distribution and enhanced tumor accumulation. This work, therefore, introduces a robust, controlled synthesis route to bottlebrush polypeptides, overcoming limitations of current polymer-based nanomedicines and, in doing so, offers valuable insights into the influence of architecture on the in vivo performance of nanomedicines.     

European higher education space: where do we go from here?

The Declaration of Bologna and subsequent documents have drastically changed the European university panorama and the future role of universities as providers of continuous education for a lifelong learning. There will be a convergence not only in academic titles, but also in the way we see university education. The previous EEE symposium gave some clues on the approaches taken by different European countries: organization of EE studies, integration of graduates into the market, and interaction with professional bodies. Bologna's outcomes were sold in Spain as a change into an American (USA) model, which, as any other model, has advantages and drawbacks. This paper deals with an open reflection on the future of university studies in Europe.     

The toxicity in vitro of titanium dioxide nanoparticles modified with noble metals on mammalian cells

The aim of the presented work was to evaluate the effect of modification of titanium dioxide nanoparticles with noble metals and their oxides on selected mammalian cells. The in vitro cytotoxicity studies of titanium dioxide (TiO₂) nanoparticles modified with Au, Ag, Pd, Ag₂O, and PdO with reference to the unmodified TiO₂ nanoparticles were presented. The evaluation of cytotoxic activity of the tested nanocomposite particles was carried out using three cell lines: Caco-2 colorectal epithelial adenocarcinoma cells, BJ normal human skin fibroblasts, and L929 mouse fibroblasts. The in vitro studies included determination of cell viability after 24 and 48 hours of exposure to the nanocomposite particles, using the MTT assay, as well as flow cytometry with Annexin V-FITC staining. Our results indicate that irrespectively of the kind of cell line and assay used, nanoparticles of unmodified titanium dioxide as well as those with addition of gold and palladium have a slight impact on cell viability at the investigated concentration range (10-200 μg/mL). Nanoparticles with addition of silver (Ag and Ag₂O), were found to have significantly higher toxic effect, the level of which varied depending on the cell line and assay used.     

Novel Atmospheric Growth Technique to Improve Both Light Absorption and Charge Collection in ZnO/Cu2O Thin Film Solar Cells

In low temperature grown ZnO/Cu₂O solar cells, there is a discrepancy between collection length and depletion width in the Cu₂O which makes the simultaneous achievement of efficient charge collection and high open‐circuit voltage problematic. This is addressed in this study by fabricating ZnO/Cu₂O/Cu₂O⁺ back surface field devices using an atmospheric atomic layer deposition (AALD) printing method to grow a sub‐200‐nm Cu₂O⁺ film on top of electrodeposited ZnO and Cu₂O layers. The AALD Cu₂O⁺ has a carrier concentration around 2 orders of magnitude higher than the electrodeposited Cu₂O, allowing the electrodeposited Cu₂O layer thickness in a back surface field cell to be reduced from 3 μm to the approximate charge collection length, 1 μm, while still allowing a high potential to be built into the cell. The dense conformal nature of the AALD layer also blocks shunt pathways allowing the voltage enhancement to be maintained. The thinner cell design reduces recombination losses and increases charge collection from both incident light and light reflected off the back electrode. Using this design, a short circuit current density of 6.32 mA cm^?2 is achieved–the highest reported J_SC for an atmospherically deposited ZnO/Cu₂O device to date.     

Wearable Activity Tracking in Car Manufacturing

A context-aware wearable computing system could support a production or maintenance worker by recognizing the worker's actions and delivering just-in-time information about activities to be performed.     

Dynophore-Based Approach in Virtual Screening: A Case of Human DNA Topoisomerase IIα

In this study, we utilized human DNA topoisomerase IIα as a model target to outline a dynophore-based approach to catalytic inhibitor design. Based on MD simulations of a known catalytic inhibitor and the native ATP ligand analog, AMP-PNP, we derived a joint dynophore model that supplements the static structure-based-pharmacophore information with a dynamic component. Subsequently, derived pharmacophore models were employed in a virtual screening campaign of a library of natural compounds. Experimental evaluation identified flavonoid compounds with promising topoisomerase IIα catalytic inhibition and binding studies confirmed interaction with the ATPase domain. We constructed a binding model through docking and extensively investigated it with molecular dynamics MD simulations, essential dynamics, and MM-GBSA free energy calculations, thus reconnecting the new results to the initial dynophore-based screening model. We not only demonstrate a new design strategy that incorporates a dynamic component of molecular recognition, but also highlight new derivates in the established flavonoid class of topoisomerase II inhibitors.