Ice crystal observations and the degree of riming in winter precipitation     

Lukas Mosimann  Matthias Steiner  Jeff L. Collett Jr.  Werner Henrich  Willi Schmid  Albert Waldvogel 《Water, air, and soil pollution》1993,68(1-2):29-42

Since snow crystals provide information on the processes leading to their formation and growth, their observation gives insight to the microphysics of cloud and precipitation. The capture of supercooled cloud droplets by snow crystals (riming) forms an important link between precipitation and cloudwater and thus plays an important role in wet deposition. In the project ‘Winter Precipitation at Mount Rigi’ ice crystals are collected at two stations at different elevations. The shape, size and degree of riming of each crystal are analyzed for more than 10000 crystals. Differences in the degree of riming of the crystals between the higher and the lower station are discussed. With the aid of Doppler radar data the location of snow crystal origin is estimated. Furthermore a relationship between the degree of riming of snow crystals and the vertical Doppler velocities is established.  相似文献   

Some cesium and potassium salts increase the water permeability of astomatous isolated plant cuticles     

Salem Elshatshat  Lukas Schreiber  Jörg Schönherr 《植物养料与土壤学杂志》2007,170(1):59-64

Salts were applied as aqueous solution to the outer surfaces of astomatous isolated cuticles, and the water was allowed to evaporate. Effects of salt residues on the surfaces of cuticles on water permeability of cuticles were measured at 25°C. A surface dose of 0.2 mol m^–2 Cs₂CO₃ and K₂CO₃ increased the water permeability of pear leaf cuticles by factors of 9.9 and 3.9, respectively. Na₂CO₃ was barely effective, and Li₂CO₃ as well as (NH₄)₂CO₃ had no influence on water permeability. Potassium applied as sulfate, nitrate, or chloride had no effect on the water permeability of pear leaf cuticles, while K⁺ salts of weak acids (0.2 mol m^–2) were effective, as they increased water permeability by factors of 5.4 (K⁺‐acetate), 3.9 (K₂CO₃), and 2.0 (K₂HPO₄), respectively. Sensitivity of Idesia polycarpa leaf cuticles to treatment with K₂CO₃ at 0.2 mol m^–2 was greatest as water permeability was increased 35‐fold, while the water permeability of cuticles from other species tested (astomatous leaf cuticles from Hedera helix, Citrus aurantium, Prunus laurocerasus, Pyrus communis, and Populus canescens; fruit cuticles from Capsicum annuum and Lycopersicon esculentum) increased only by factors ranging from 1.7 to 3.9. Data are discussed in relation to swelling and ion‐exchange properties of cuticles.  相似文献   

Heart transplantation in animal experiments     

J Kraft-Kinz  G Friehs  H Lukas 《Wiener tier?rztliche Monatsschrift》1970,57(5):184-188

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Proanthocyanidins: target compounds as antibacterial agents     

Mayer R  Stecher G  Wuerzner R  Silva RC  Sultana T  Trojer L  Feuerstein I  Krieg C  Abel G  Popp M  Bobleter O  Bonn GK 《Journal of agricultural and food chemistry》2008,56(16):6959-6966

Grape seeds accumulate in huge quantities as byproduct during wine production and are therefore a cheap source for pharmacologically active agents. However, studies prove poor antibacterial activity, and results of analyses are sometimes contradictory. The aim of this study was, thus, to determine the antibacterial activity of grape seed extracts with special focus on the chromatographic characterization of active fractions. In the course of these investigations, extraction protocols were optimized so that microwave-assisted extraction (MAE) guaranteed highest preconcentration efficiency. Proanthocyanidins, monomeric flavonoid aglycones, as well as some of their glycosides could be identified within yielded extracts via high-performance liquid chromatography-mass spectrometry (HPLC-MS). By that means the coherence number of possible isomers of procyanidins was approximated by a newly developed equation. As far as antibacterial activity determined via screening tests is concerned, the extracts generally have been found to be positively responsive toward 10 different gram-positive and gram-negative bacteria strains. After fractionation of the raw extracts, proanthocyanidins P2, P3, P4 and gallate esters P2G and P3G (P = proanthocyanidin consisting of catechin and epicatechin units, n = oligomerization degree, G = gallate ester) were determined as active antibacterial agents toward 10 different pathogens. Only moderate activity was found for monomeric flavonoid fractions.  相似文献   

Does closure of traditionally managed open woodlands threaten epigeic invertebrates? Effects of coppicing and high deer densities   总被引：1，自引：0，他引：1  

Lukas Spitzer  Martin Konvicka  Jiri Benes  Ivan H. Tuf 《Biological conservation》2008,141(3):827-837

The demise of traditional woodland management techniques, such as coppicing or woodland pasture, is causing a gradual closure of formerly sparse lowland woods across Central Europe. It is established that these processes threaten such organisms as butterflies and higher plants. Effects on other groups, such as epigeic invertebrates, are little known, hindering rational conservation decisions. We investigated the effects of stand openness on three epigeic groups, carabids (Carabidae), arachnids (Araneae + Opiliones) and myriapods-isopods (Chilopoda + Diplopoda + Oniscidea), in a lowland deciduous wood in the Czech Republic. Situating some of the traps in an intensive deer park allowed a simultaneous assessment of effects of high vs. low ungulate densities. Carabids reached the highest species richness in either sparse stands with low game or dense stands, high game. More arachnids occurred under low game and in sparse stands than under high game density and in dense stands. The highest richness of myriapods-isopods was in sparse stands with low game. Ordinations revealed that species of conservation concern (‘relic species’ according to C. European authors) tended to be associated with sparse stands and low game. A considerable proportion of epigeic woodland invertebrates, including many species of conservation concern, depends on preserving highly heterogeneous sparse canopy conditions. Restoring such conditions in selected areas will benefit these sensitive open woodland specialists while causing minimum harm to specialists of dense stands, that likely prosper in commercially managed high forests.  相似文献   

Performance and behaviour of the microbial community of an anaerobic biogas digester using sugar beet silage as mono-substrate     

Burak Demirel  Serhat Ergun  Lukas Neumann  Paul Scherer 《Biosystems Engineering》2009,102(4):444-452

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Recent Developments on the Synthesis and Bioactivity of Ilamycins/Rufomycins and Cyclomarins,Marine Cyclopeptides That Demonstrate Anti-Malaria and Anti-Tuberculosis Activity     

Uli Kazmaier  Lukas Junk 《Marine drugs》2021,19(8)

Ilamycins/rufomycins and cyclomarins are marine cycloheptapeptides containing unusual amino acids. Produced by Streptomyces sp., these compounds show potent activity against a range of mycobacteria, including multidrug-resistant strains of Mycobacterium tuberculosis. The cyclomarins are also very potent inhibitors of Plasmodium falciparum. Biosynthetically the cyclopeptides are obtained via a heptamodular nonribosomal peptide synthetase (NRPS) that directly incorporates some of the nonproteinogenic amino acids. A wide range of derivatives can be obtained by fermentation, while bioengineering also allows the mutasynthesis of derivatives, especially cyclomarins. Other derivatives are accessible by semisynthesis or total syntheses, reported for both natural product classes. The anti-tuberculosis (anti-TB) activity results from the binding of the peptides to the N-terminal domain (NTD) of the bacterial protease-associated unfoldase ClpC1, causing cell death by the uncontrolled proteolytic activity of this enzyme. Diadenosine triphosphate hydrolase (PfAp3Aase) was found to be the active target of the cyclomarins in Plasmodia. SAR studies with natural and synthetic derivatives on ilamycins/rufomycins and cyclomarins indicate which parts of the molecules can be simplified or otherwise modified without losing activity for either target. This review examines all aspects of the research conducted in the syntheses of these interesting cyclopeptides.  相似文献   

Optimal Estimation Versus MCMC for $$\mathrm{{CO}}_{2}$$ Retrievals     

Jenny Brynjarsdottir  Jonathan Hobbs  Amy Braverman  Lukas Mandrake 《Journal of Agricultural, Biological & Environmental Statistics》2018,23(2):297-316

The Orbiting Carbon Observatory-2 (OCO-2) collects infrared spectra from which atmospheric properties are retrieved. OCO-2 operational data processing uses optimal estimation (OE), a state-of-the-art approach to inference of atmospheric properties from satellite measurements. One of the main advantages of the OE approach is computational efficiency, but it only characterizes the first two moments of the posterior distribution of interest. Here we obtain samples from the posterior using a Markov Chain Monte Carlo (MCMC) algorithm and compare this empirical estimate of the true posterior to the OE results. We focus on 600 simulated soundings that represent the variability of physical conditions encountered by OCO-2 between November 2014 and January 2016. We treat the two retrieval methods as ensemble and density probabilistic forecasts, where the MCMC yields an ensemble from the posterior and the OE retrieval result provide the first two moments of a normal distribution. To compare these methods, we apply both univariate and multivariate diagnostic tools and proper scoring rules. The general impression from our study is that when compared to MCMC, the OE retrieval performs reasonably well for the main quantity of interest, the column-averaged \(\mathrm{{CO}}_{2}\) concentration \(X_{\mathrm{{CO}}_{2}}\), but not for the full state vector \(\mathbf {X}\) which includes a profile of \(\mathrm{{CO}}_{2}\) concentrations over 20 pressure levels, as well as several other atmospheric properties.Supplementary materials accompanying this paper appear on-line.  相似文献   

Interaction of minerals,organic matter,and microorganisms during biogeochemical interface formation as shown by a series of artificial soil experiments     

Geertje?J.?PronkEmail author  Katja?Heister  Cordula?Vogel  Doreen?Babin  J?rg?Bachmann  Guo-Chun?Ding  Franziska?Ditterich  Martin?H.?Gerzabek  Julia?Giebler  Michael?Hemkemeyer  Ellen?Kandeler  Yamuna?Kunhi Mouvenchery  Anja?Miltner  Christian?Poll  Gabriele?E.?Schaumann  Kornelia?Smalla  Annelie?Steinbach  Irina?Tanuwidjaja  Christoph?C.?Tebbe  Lukas?Y.?Wick  Susanne?K.?Woche  Kai?U.?Totsche  Michael?Schloter  Ingrid?K?gel-Knabner 《Biology and Fertility of Soils》2017,53(1):9-22

Our understanding of the interactions between minerals, organic matter, and microorganisms at so-called biogeochemical interfaces in soil is still hampered by the inherent complexity of these systems. Artificial soil maturation experiments can help to bridge a gap in complexity between simple abiotic sorption experiments and larger-scale field experiments. By controlling other soil-forming factors, the effect of a particular variable can be identified in a simplified system. Here, we review the findings of a series of artificial soil incubation experiments with the aim of revealing general trends and conclusions. The artificial soils were designed to determine the effect of mineral composition and charcoal presence on the development of abiotic and biotic soil properties during maturation. In particular, the development of soil aggregates, organic matter (OM) composition and turnover, sorption properties, and the establishment of microbial community composition and function were considered. The main objectives of the research were to determine (1) how surface properties and sorption of chemicals modify biogeochemical interfaces; (2) how much time is required to form aggregates from mixtures of pure minerals, OM, and a microbial inoculum; and (3) how the presence of different mineral and charcoal surfaces affects aggregation, OM turnover, and the development of microbial community composition.  相似文献   

Impact of climate and lithology on soil phytolith-occluded carbon accumulation in eastern China     

Xiaodong Zhang  Zhaoliang Song  Zhiqi Zhao  Lukas Van Zwieten  Jianwu Li  Linan Liu  Song Xu  Hailong Wang 《Journal of Soils and Sediments》2017,17(2):481-490

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