Campholenic aldehyde ozonolysis: a mechanism leading to specific biogenic secondary organic aerosol constituents

In the present study, campholenic aldehyde ozonolysis was performed to investigate pathways leading to specific biogenic secondary organic aerosol (SOA) marker compounds. Campholenic aldehyde, a known α-pinene oxidation product, is suggested to be a key intermediate in the formation of terpenylic acid upon α-pinene ozonolysis. It was reacted with ozone in the presence and absence of an OH radical scavenger, leading to SOA formation with a yield of 0.75 and 0.8, respectively. The resulting oxidation products in the gas and particle phases were investigated employing a denuder/filter sampling combination. Gas-phase oxidation products bearing a carbonyl group, which were collected by the denuder, were derivatised by 2,4-dinitrophenylhydrazine (DNPH) followed by liquid chromatography/negative ion electrospray ionisation time-of-flight mass spectrometry analysis and were compared to the gas-phase compounds detected by online proton-transfer-reaction mass spectrometry. Particle-phase products were also analysed, directly or after DNPH derivatisation, to derive information about specific compounds leading to SOA formation. Among the detected compounds, the aldehydic precursor of terpenylic acid was identified and its presence was confirmed in ambient aerosol samples from the DNPH derivatisation, accurate mass data, and additional mass spectrometry (MS² and MS³ fragmentation studies). Furthermore, the present investigation sheds light on a reaction pathway leading to the formation of terpenylic acid, involving α-pinene, α-pinene oxide, campholenic aldehyde, and terpenylic aldehyde. Additionally, the formation of diaterpenylic acid acetate could be connected to campholenic aldehyde oxidation. The present study also provides insights into the source of other highly functionalised oxidation products (e.g. <i>m</i> / <i>z</i> 201, C₉H₁₄O₅ and <i>m</i> / <i>z</i> 215, C₁₀H₁₆O₅), which have been observed in ambient aerosol samples and smog chamber-generated monoterpene SOA. The <i>m</i> / <i>z</i> 201 and 215 compounds were tentatively identified as a C₉- and C₁₀-carbonyl-dicarboxylic acid, respectively, based on reaction mechanisms of campholenic aldehyde and ozone, as well as detailed interpretation of mass spectral data, in conjunction with the formation of corresponding DNPH derivatives

Selektion anbauwürdiger Saflor-Formen für den Ökologischen Landbau aus einem zweijährigen Screening-Experiment

Als alternative Ölpflanze mit hervorragender Speiseölqualität könnte Saflor für den ökologischen Landbau dort in Frage kommen, wo Raps und Sonnenblumen weniger hohe Erträge zu liefern imstande sind. In der vorliegenden Studie sollte die Anbauwürdigkeit des Saflors unter den Bedingungen des Ökologischen Landbaues mit einem Screening von 741 ausgewählten Formen dieser Art überprüft werden. Das Experiment fand 2002 an zwei Standorten statt. Eine hieraus getroffene Auswahl von 65 geeigneten Herkünften wurde 2003 in einer dreiortigen Leistungsprüfung weiter getestet. 2002 wurden sowohl bei morphologischen als auch agronomisch wichtigen Merkmalen große Unterschiede zwischen den Herkünften gefunden. Besonders in der Anfälligkeit für verschiedene Krankheiten zeigte das Material eine große Variabilität. Neben ertragslosen Formen konnten eine Reihe von Genotypen mit ausreichendem Kornansatz geerntet werden, die zusätzlich im Mittel einen Kernanteil bis zu 40% aufwiesen. Das weitergeprüfte Material zeigte 2003 eine mit den Daten aus 2002 gut übereinstimmende Krankheitsanfälligkeit. Es kann hieraus gefolgert werden, dass es bei Saflor anbauwürdige Formen gibt, die auch unter unseren eher humiden Klimabedingungen noch ausreichende Leistungen erbringen können

Enhanced Performance of Dye-Sensitized Solar Cells based on TiO2 Nanotube Membranes using Optimized Annealing Profile

We use free-standing TiO2 nanotube membranes that are transferred onto FTO slides in front-side illuminated dye-sensitized solar cells (DSSCs). We investigate the key parameters for solar cell arrangement of self-ordered anodic TiO2 nanotube layers on the FTO substrate and namely the influence of the annealing procedure on the DSSC light conversion efficiency. The results show that using an optimal temperature annealing profile can significantly enhance the DSSC efficiency (in our case 9.8 %), as it leads to a markedly lower density of trapping states in the tube oxide, and thus to strongly improved electron transport properties

Mixed-ligand lanthanide complexes supported by ditopic bis(imino-methyl)-phenol/calix[4]arene macrocycles: synthesis, structures, and luminescence properties of [Ln2(L2)(MeOH)2] (Ln = La, Eu, Tb, Yb)

The lanthanide binding ability of a macrocyclic ligand H6L2 comprising two bis(iminomethyl)phenol and two calix[4]arene units has been studied. H6L2 is a ditopic ligand which provides dinuclear neutral complexes of composition [Ln2(L2)(MeOH)2] (Ln = La (1), Eu (2), Tb (3), and Yb (4)) in very good yield. X-ray crystal structure analyses for 2 and 3 show that (L2)6- accommodates two seven coordinated lanthanide ions in a distorted monocapped trigonal prismatic/octahedral coordination environment. UV-vis spectroscopic titrations performed with La3+, Eu3+, Tb3+ and Yb3+ ions in mixed MeOH/CH2Cl2 solution (I = 0.01 M NBu4PF6) reveal that a 2 : 1 (metal : ligand) stoichiometry is present in solution, with log K11 and K21 values ranging from 5.25 to 6.64. The ratio α = K11/K21 of the stepwise formation constants for the mononuclear (L2 + M = ML2, log K11) and the dinuclear complexes (ML2 + M = M2L2, log K21) was found to be invariably smaller than unity indicating that the binding of the first Ln3+ ion augments the binding of the second Ln3+ ion. The present complexes are less luminescent than other seven-coordinated Eu and Tb complexes, which can be traced to vibrational relaxation of excited EuIII and TbIII states by the coligated MeOH and H2O molecules and/or low-lying ligand-to-metal charge-transfer (LMCT) states. © 2020 The Royal Society of Chemistry

General Protein Diffusion Barriers Create Compartments within Bacterial Cells

In eukaryotes, the differentiation of cellular extensions such as cilia or neuronal axons depends on the partitioning of proteins to distinct plasma membrane domains by specialized diffusion barriers. However, examples of this compartmentalization strategy are still missing for prokaryotes, although complex cellular architectures are also widespread among this group of organisms. This study reveals the existence of a protein-mediated membrane diffusion barrier in the stalked bacterium Caulobacter crescentus. We show that the Caulobacter cell envelope is compartmentalized by macromolecular complexes that prevent the exchange of both membrane and soluble proteins between the polar stalk extension and the cell body. The barrier structures span the cross-sectional area of the stalk and comprise at least four proteins that assemble in a cell-cycle-dependent manner. Their presence is critical for cellular fitness because they minimize the effective cell volume, allowing faster adaptation to environmental changes that require de novo synthesis of envelope proteins

Boosting Anti-Inflammatory Potency of Zafirlukast by Designed Polypharmacology

Multitarget design offers access to bioactive small molecules with potentially superior efficacy and safety. Particularly multifactorial chronic inflammatory diseases demand multiple pharmacological interventions for stable treatment. By minor structural changes, we have developed a close analogue of the cysteinyl-leukotriene receptor antagonist zafirlukast that simultaneously inhibits soluble epoxide hydrolase and activates peroxisome proliferator-activated receptor \u3b3. The triple modulator exhibits robust anti-inflammatory activity in vivo and highlights the therapeutic potential of designed multitarget agents

Resistivity of a Metal between the Boltzmann Transport Regime and the Anderson Transition

We study the transport properties of a finite three dimensional disordered conductor, for both weak and strong scattering on impurities, employing the real-space Green function technique and related Landauer-type formula. The dirty metal is described by a nearest neighbor tight-binding Hamiltonian with a single s-orbital per site and random on-site potential (Anderson model). We compute exactly the zero-temperature conductance of a finite size sample placed between two semi-infinite disorder-free leads. The resistivity is found from the coefficient of linear scaling of the disorder averaged resistance with sample length. This ``quantum'' resistivity is compared to the semiclassical Boltzmann expression computed in both Born approximation and multiple scattering approximation.Comment: 5 pages, 3 embedded EPS figure

Mapping the Pore Architecture of Structured Catalyst Monoliths from Nanometer to Centimeter Scale with Electron and X-ray Tomographies

The hierarchical pore systems of Pt/Al2O3 exhaust gas aftertreatment catalysts were analyzed with a collection of correlative imaging techniques to monitor changes induced by hydrothermal aging. Synergistic imaging with laboratory X-ray microtomography, synchrotron radiation ptychographic X-ray computed nanotomography, and electron tomography allowed quantitative observation of the catalyst pore architecture from centimeter to nanometer scale. Thermal aging at 750 °C in air and hydrothermal aging at 1050 °C in 10% H2O/air caused increasing structural degradation, which manifested as widespread sintering of Pt particles, increased volume and quantity of macropores (>20 nm), and reduction in effective surface area coupled with decreasing volume and frequency of mesopores (2-20 nm) and micropores (<2 nm). Electron tomography unraveled the three-dimensional (3D) structure with high resolution allowing visualization of meso- and macropores but with samples of maximum 300 nm thickness. To complement this, hard X-ray ptychographic tomography produced quantitative 3D electron density maps of 5 μm diameter samples with spatial resolution <50 nm, effectively filling the resolution gap between electron tomography and hard X-ray microtomography. The obtained 3D volumes are an essential input for future computational modeling of fluid dynamics, mass transport, or diffusion properties and may readily complement bulk one-dimensional porosimetry measurements or simulated porosity

Decoding information in the human hippocampus: a user's guide

Multi-voxel pattern analysis (MVPA), or 'decoding', of fMRI activity has gained popularity in the neuroimaging community in recent years. MVPA differs from standard fMRI analyses by focusing on whether information relating to specific stimuli is encoded in patterns of activity across multiple voxels. If a stimulus can be predicted, or decoded, solely from the pattern of fMRI activity, it must mean there is information about that stimulus represented in the brain region where the pattern across voxels was identified. This ability to examine the representation of information relating to specific stimuli (e.g., memories) in particular brain areas makes MVPA an especially suitable method for investigating memory representations in brain structures such as the hippocampus. This approach could open up new opportunities to examine hippocampal representations in terms of their content, and how they might change over time, with aging, and pathology. Here we consider published MVPA studies that specifically focused on the hippocampus, and use them to illustrate the kinds of novel questions that can be addressed using MVPA. We then discuss some of the conceptual and methodological challenges that can arise when implementing MVPA in this context. Overall, we hope to highlight the potential utility of MVPA, when appropriately deployed, and provide some initial guidance to those considering MVPA as a means to investigate the hippocampus