4,932 research outputs found
Mold attack on frescoes and stone walls of Gradac monastery
Microfungi can colonize stone surfaces and form sub-aerial biofilms which can lead to biodeterioration of historic monuments. In this investigation samples for mycological analyses were collected from stone material with visible alteration on stone walls of Gradac monastery exterior. The prevailing fungi found on stone walls were dematiaceous hyphomycetes with melanized hyphae and reproductive structures (Alternaria, Aureobasidium, Cladosporium and Epicoccum species). The frescoes inside the monastery building were also analyzed for the presence of mycobiota. The predominant fungi found on frescoes were osmophilic species from genera Aspergillus and Penicillium. The significant result is identification of human pathogen species Aspergillus fumigatus on frescoes
Hydrogen storage in a layered flexible [Ni2(btc)(en)2]n coordination polymer
[Ni2(btc)(en)2]n coordination polymer exhibits a layered two-dimensional structure with weak interaction between the layers. Correlation of experimental measurements, DFT calculations and molecular simulations demonstrated that its structural features, primarily the inherent flexibility of the layered polymeric structure, lead to improved hydrogen storage performance at room temperature, due to significant enhancement in isosteric heats of hydrogen adsorption. Volumetric measurements of hydrogen adsorption at room temperature show up to 0.3 wt.% hydrogen absorbed at 303 K and 2.63 bar of hydrogen pressure, with isosteric heats of adsorption of about 12.5 kJ molā1. Predicted performance at room temperature is 1.8 wt.% at 48 bar and 3.5 wt.% at 100 bar, better than both MOF-5 and NU-100, with calculated values of isosteric heats for adsorption of hydrogen in 8ā13 kJ molā1 range at both 77 K and 303 K. Grand canonical Monte Carlo calculations show that this material, at 77 K, exhibits gravimetric hydrogen densities of more than 10 wt.% (up to 8.3 wt.% excess) with the corresponding volumetric density of at least 66 gLā1, which is comparable to MOF-5, but achieved with considerably smaller surface area of about 2500 m2 gā1. This study shows that layered two-dimensional MOFs could be a step towards MOF systems with significantly higher isosteric heats of adsorption, which could provide better room temperature hydrogen storage capabilities.This is the peer reviewed version of the following article: BlagojeviÄ, V.A., LukiÄ, V., BegoviÄ, N.N., MariÄiÄ, A.M., MiniÄ, D.M., 2016, āHydrogen storage in a layered flexible [Ni2(btc)(en)2]n coordination polymerā, International Journal of Hydrogen Energy, http://dx.doi.org/10.1016/j.ijhydene.2016.08.20
Calculation of vibrations of a single degree of freedom system
The three node numerical integration scheme with the displacement and velocity as the nodal variables for integration of the second order differential equation using finite elements in time on the basis of the method of least squares is proposed. The precision of integration is investigated and compared with the corresponding procedure based on the method of Galerkin. The error measure is introduced which shows the higher precision of the least squares techniqu
Measurement of the solenoid magnetic field
We describe the machine used to map the solenoid field and the data sets that were collected. The bulk of the note describes the analysis of this data. A series of small corrections are made; some taken from surveys and some derived from the data itself. Two fitting methods are defined and applied to all data sets. The final result is that the field map at normal operating current can be fitted to a function that obeys Maxwell with an r.m.s. residual of less than 5 Gauss. Systematic errors on the measurement of track sagitta due to the field uncertainty are estimated to be in the range 2.3E-4 to 12E-4, depending on the track rapidity. Finally, the representation of the map in Athena is briefly described
Dependence of Drift Tube Performance on the Anode Wire Diameter
Cylindrical pressurized drift tubes with different anode wire diameters wereoperated in a 170~GeV muon test beam. The dependences of spatialresolution, efficiency and streamer probability on the anode wirediameter were measured. The resolution measurements are compared with a simulation
Measurement of the ATLAS solenoid magnetic field
ATLAS is a general purpose detector designed to explore a wide range of physics at the Large Hadron Collider. At the centre of ATLAS is a tracking detector in a 2 T solenoidal magnetic field. This paper describes the machine built to map the field, the data analysis methods, the final results, and their estimated uncertainties. The remotely controlled mapping machine used pneumatic motors with feedback from optical encoders to scan an array of Hall probes over the field volume and log data at more than 20 000 points in a few hours. The data were analysed, making full use of the physical constraints on the field and of our knowledge of the solenoid coil geometry. After a series of small corrections derived from the data itself, the resulting maps were fitted with a function obeying Maxwell's equations. The fit residuals had an r.m.s. less than 0.5 mT and the systematic error on the measurement of track sagitta due to the field uncertainty was estimated to be in the range 0.02 % to 0.12 % depending on the track rapidity
CLIC Beam Delivery System
We review the present design for the CLIC beam delivery system as configured for 3 TeV and for 500 GeV, describe some recent developments (including the combined effect of solenoid, crab cavity, and crossing angle), highlight open questions, and outline future studies
Total Synthesis and Functional Evaluation of IORs, Sulfonolipidābased Inhibitors of Cell Differentiation in Salpingoeca rosetta
The choanoflagellate Salpingoeca rosetta is an important model system to study the evolution of multicellularity. In this study we developed a new, modular, and scalable synthesis of sulfonolipid IORā1A (six steps, 27ā% overall yield), which acts as bacterial inhibitor of rosette formation in S.ā
rosetta . The synthesis features a decarboxylative crossācoupling reaction of a sulfonic acidācontaining tartaric acid derivative with alkyl zinc reagents. Synthesis of 15 modified IORā1A derivatives, including fluorescent and photoaffinityābased probes, allowed quantification of IORā1A, localization studies within S.ā
rosetta cells, and evaluation of structureāactivity relations. In a proof of concept study, an inhibitory bifunctional probe was employed in proteomic profiling studies, which allowed to deduce binding partners in bacteria and S.ā
rosetta . These results showcase the power of synthetic chemistry to decipher the biochemical basis of cell differentiation processes within S.ā
rosetta
Space charge in drift chambers operated with the Xe,CO2(15%) mixture
Using prototype modules of the ALICE Transition Radiation Detector we
investigate space charge effects and the dependence of the pion rejection
performance on the incident angle of the ionizing particle. The average pulse
height distributions in the drift chambers operated with the Xe,CO2(15%)
mixture provide quantitative information on the gas gain reduction due to space
charge accumulating during the drift of the primary ionization. Our results
demonstrate that the pion rejection performance of a TRD is better for tracks
which are not at normal incidence to the anode wires. We present detailed
simulations of detector signals, which reproduce the measurements and lend
strong support to our interpretation of the measurements in terms of space
charge effects.Comment: 18 pages, 10 figures, accepted for publication in Nucl.Instrum.Meth.
A. Data files available at http://www-alice.gsi.de/tr
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