Optical system design and experimental evaluation of a coherent Doppler wind Lidar system for the predictive control of wind turbine

The control of wind turbine blade pitch systems by Lidar assisted wind speed prediction has been proposed to increase the electric power generation and reduce the mechanical fatigue load on wind turbines. However, the sticking point of such Lidar systems is the price. Hence, our objective is to develop a more cost efficient Lidar system to support the pitch control of horizontal axis wind turbines and therefore to reduce the material requirement, lower the operation and maintenance costs and decrease the cost of wind energy in the long term. Compared to the state of the art Lidar systems, a laser with a shorter coherence length and a corresponding fiber delay line is introduced for reducing the costs. In this paper we present the experimental evaluation of different sending and receiving optics designs for such a system from a free space laboratory setup.     

Dark field nanoparticle tracking analysis for size characterization of plasmonic and non-plasmonic particles

Journal of Nanoparticle Research - Co3O4 nanocubes with perfect shape were synthesized by a simple hydrothermal route in which Co3O4 was directly prepared in the one-pot process with aging...     

Access to Intrinsically Glucoside‐Based Microspheres with Boron Affinity

Intrinsically glucoside‐based microspheres are prepared in olive oil via a water in oil inverse suspension polymerization. The microspheres are characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) microscopy, and X‐ray photoelectron spectroscopy (XPS), evidencing the intrinsic glucose character of the spheres. A novel boronic acid fluorescent molecule was subsequently conjugated to the microspheres in an aqueous environment, exhibiting the spatial and uniform distribution of glucoside as well as the affinity of the microspheres to bind with boron, evidenced via fluorescence spectroscopy measurements.

     

Modeling aspects of flow and solute transport simulations in water disinfection tanks

Water disinfection tanks such as chlorine and ozone contactors typically consist of multiple compartments featuring a serpentine flow pattern. Due to the complex hydrodynamics, the design and optimization of these tanks are often carried out by employing computational fluid dynamics (CFD) simulations. The present study demonstrates the influence of certain modeling aspects when the widely used Reynolds-Averaged Navier Stokes (RANS) based CFD approach to predict hydrodynamics and disinfection performance is employed. Three different contact tank geometries are examined numerically using RANS. The time-averaged velocity predictions are reasonably accurate when compared to validation data. However, in baffled contact tanks, the time-averaged flow differs quite significantly from the instantaneous flow, with the consequence that RANS-based models require careful calibration of the turbulent mixing parameter, i.e., the turbulent Schmidt number, when computing transport of solutes.     

Comparison between vacuum sublimed matrices and conventional dried droplet preparation in MALDI-TOF mass spectrometry

The properties of several cinnamic acid compounds used as matrices for matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) were investigated as standard dried droplet (DD) and vacuum sublimed preparations. The differences between both preparation methods were analyzed with regard to matrix grain size, internal ion energy, initial velocity, analyte intensity, and analyte incorporation depth. Some of the used cinnamic acid derivatives exhibit clearly reduced grain sizes as sublimed preparations compared with standard DD approaches. In these cases higher effective temperatures could be measured accompanied by increased analyte intensities, which can be explained by stronger volatilization processes caused by a hindered heat dissipation resulting in a raised analyte transfer into the gas phase. For all sublimed compounds, a strong increase of the initial ion velocity compared with DD preparations could be measured. Higher initial ion velocities correlate with a decrease in internal ion energy which might be attributed to the very uniform crystal morphology exhibited by sublimed compounds. For sublimed matrices without reduced grain size, at least slightly higher analyte intensities could be detected at raised laser fluences. Analyte accumulation in the uppermost matrix layers or the detected higher ion stability can be explanations for these results.     

Reactions of free gold cluster cations with H2O, CH3Cl, and mixtures thereof

The reactions of the mass-selected gas-phase gold cluster cations Au₃⁺ and Au₅⁺ with H₂O, CH₃Cl, and mixtures of these reactants were studied under well-defined multi-collision conditions in an octopole ion trap. The reaction of CH₃Cl with the gold cations was found to proceed fast at room temperature, leading to the adsorption of one CH₃Cl molecule at each ‘corner’ atom of the cluster ion. This strong adsorption hindered the coadsorption of other reactants like H₂O. However, a considerable reduction of the CH₃Cl partial pressure led to distinct patterns of H₂O/CH₃Cl coadsorption products. Furthermore, the mass spectra indicated the loss of hydrogen after the reaction of CH₃Cl with Au₃⁺.     

Dynamic Nuclear Polarization with a Rigid Biradical

A new polarizing agent with superior performance in dynamic nuclear polarization experiments is introduced, and utilizes two TEMPO (2,2,6,6‐tetramethylpiperidine‐1‐oxyl) moieties connected through a rigid spiro tether (see structure). The observed NMR signal intensities were enhanced by a factor of 1.4 compared to those of TOTAPOL, a previously described TEMPO‐based biradical with a flexible tether.

     

Total Synthesis of Meloscine by a [2+2]‐Photocycloaddition/Ring‐Expansion Route

The stereogenic centers at C3 and C12 of meloscine ( 3 ) can be established in the photochemical key step 1 → 2 . 1,2‐retro‐Benzilic acid rearrangement to a five‐membered ring, reductive amination, Claisen rearrangement, and ring‐closing metathesis are further key steps in the transformation of cyclobutane 2 into the target molecule 3 (14 steps, 9 % overall yield). Enantioselective access to (+)‐meloscine was possible when the [2+2]‐photocycloaddition was conducted in the presence of a chiral template.

     

Sequencing hydroxyethylamine-containing peptides via Edman degradation

Hydroxyethylamine-containing peptides can be sequenced by automated Edman degradation to provide sequence information for peptide segments on either side of the peptide backbone modification. [reaction: see text]