Thermal decomposition of lanthanum selenate pentahydrate in air and nitrogen

Thermogravimetric studies, supported by IR and X-ray diffraction measurements, were carried out for La₂(SeO₄)₃ · 5H₂O in order to establish its decomposition scheme under various experimental conditions. Several analytical methods were tested for the simultaneous determination of (Se(IV) and Se(VI) in the quenched samples. TG weight losses and analyses of the solid intermediates indicated that after dehydration La₂(SeO₄)₃ decomposes in nitrogen mainly to oxyselenite(IV) compoundsvia the normal selenite(IV) but in air the oxyselenate La₂O₂SeO₄ was detected as one of the intermediates. The final product of the thermal degradation is La₂O₃. TG curves of La₂(SeO₄)₃ · 5H₂O were also compared with those obtained for the isostructural neodymium compound.     

Measuring turbulence energy with PIV in a backward-facing step flow

Turbulence energy is estimated in a backward-facing step flow with three-component (3C, stereo) particle image velocimetry (PIV). Estimates of turbulence energy transport equation for convection, turbulence transport, turbulence production, viscous diffusion, and viscous dissipation in addition to Reynolds stresses are computed directly from PIV data. Almost all the turbulence energy terms in the backward-facing step case can be measured with 3C PIV, except the pressure-transport term, which is obtained by difference of the other turbulence energy terms. The effect of the velocity spatial sampling resolution in derivative estimations is investigated with four two-dimensional PIV measurement sets. This sampling resolution information is used to calibrate the turbulence energies estimated by 3C PIV measurements. The focus of this study is on the separated shear layer of the backward-facing step. The measurements with 3C PIV are carried out in a turbulent water flow at Reynolds number of about 15,000, based on the step height h and the inlet streamwise maximum mean velocity U₀. The expansion ratio (ER) is 1.5. Turbulence energy budget profiles in locations x/h=4, x/h=6, and x/h=10 are compared with DNS data of a turbulent flow. The shapes of profiles agree well with each other. Different ERs between the PIV case (1.5) and the DNS case (1.2) cause higher values for the turbulence energies measured by PIV than the energies by DNS when x/h=10 is approached. PIV results also show that the turbulence energy level in these experiments is generally higher than that of the DNS data.     

Spectator recoil in intermediate-energy heavy-ion collisions

Recoil momenta of heavy spectators in intermediate-energy heavy-ion collisions of the order of 50–500 MeV per nucleon have been investigated within a statistical transfer model. Special emphasis was put on the role of fluctuations in defining the reaction geometry from correlation experiments involving recoil momenta and masses.     

Screening of Hydrogels for Human Pluripotent Stem Cell–Derived Neural Cells: Hyaluronan‐Polyvinyl Alcohol‐Collagen‐Based Interpenetrating Polymer Network Provides an Improved Hydrogel Scaffold

There is a clear need for novel in vitro models, especially for neuronal applications. Development of in vitro models is a multiparameter task consisting of cell‐, biomaterial‐, and environment‐related parameters. Here, three different human origin neuronal cell sources are studied and cultured in various hydrogel 3D scaffolds. For the efficient evaluation of complex results, an indexing method for data is developed and used in principal component analysis (PCA). It is found that no single hydrogel is superior to other hydrogels, and collagen I (Col1) and hyaluronan–poly(vinyl alcohol) (HA1‐PVA) gels are combined into an interpenetrating network (IPN) hydrogel. The IPN gel combines cell supportiveness of the collagen gel and stability of the HA1‐PVA gel. Moreover, cell adhesion is studied in particular and it is found that adhesion of neurons differs from that observed for fibroblasts. In conclusion, the HA1‐PVA‐col1 hydrogel is a suitable scaffold for neuronal cells and supports adhesion formation in 3D.     

Single-nucleon and heavy recoil spectra in intermediate energy heavy-ion reactions

We study the nucleon emission spectra from a local large-volume hot zone formed in intermediate energy (～ 20–100 MeV/nucleon) heavy-ion reactions. The hot zone is continuously being cooled by nucleon emission while the cold nuclear matter surrounding the hot zone is being heated up by nucleon absorption until full thermal equilibrium is reached. The sequential evaporation from the equilibrated reaction complex is followed up. The recoil properties of the residual heavy fragments are also investigated.     

Analysis of the compounds in the synthesis mixtures of hydroxy acids by a gradient programmed RP-HPLC with UV/vis and RI detectors

Summary A gradient programmed reversed phase high-performance liquid chromatographic (RP-HPLC) method is described for the quantitative determination of some aldehydes, hydroxy aldehydes, unsaturated aldehydes, hydroxy carboxylic acids, carboxylic acids, alcohols and polyols using an ultraviolet and a refractive index detector in series. The sample matrices are synthesis mixtures of hydroxy carboxylic acids. The structures of the hydroxy aldehyde intermediates are determined by¹³C NMR and the influence of sample preparation on analysis results is discussed. The limits of detection and the precision of the method are evaluated.     

Treatment of moisture condensation on fins

An analysis of natural convection from a vertical plate fin when the fin base temperature is below the dew point of the surrounding air is presented in this paper. The analytical solution derived is based upon a constant heat and mass transfer coefficient and is also valid for forced convection. The results of this simplified theory are compared with a numerical solution where the coupling of convection and conduction is taken into account. An experimental verification of the results is also shown.

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Aus Kondensation von Feuchtigkeit an Rippen

Zusammenfassung Es wird eine Analyse der freien Konvektion an einer vertikalen plattenförmigen Rippe dargestellt, bei der die Temperatur im Anfangsbereich der Rippe unterhalb des Taupunktes der umgebenden Luft liegt. Die abgeleitete analytische Lösung beruht auf einem konstanten Wärme- und Stoffübergangskoeffizienten und gilt auch für die erzwungene Konvektion. Die Resultate dieser vereinfachten Theorie werden mit einer numerischen Lösung verglichen, in der die Verbindung von Konvektion und Wärmeleitung in Betracht gezogen wird. Angeführt wird auch eine experimentelle Bestätigung der Resultate.

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Nomenclature a _f thermal diffusivity of air - A, B constants in Eq. (7) - c constant defined in Eq. (3) - D diffusion coefficient - f an arbitrary function ofT andx in Eq. (12) - F ₁,F ₂ coefficients in differential Eq. (13) - g gravitational acceleration - h heat transfer coefficient - h _m mass transfer coefficient - k thermal conductivity of fin - k _f thermal conductivity of air - l latent heat of moisture condensation - L total length of fin - L _w length of wet fin - m parameter, (h/kt)^1/2 - m _l dimensionless parameter, 1+ B/T _r - m _y parameter,m m _l ^1/2 - p pressure of surrounding air - p _ws saturation pressure of water vapor - p _w partial pressure of water vapor in air - Pr Prandtl number,/a _f - q total heat fluxl - q _c convective heat flux - q _m heat flux - q _r radiative heat flux - R parameter in Eq. (14) - R _w specific gas constant of water vapor - t half thickness of fin - T temperature - T _b base temperature of wet fin - T _c base temperature of dry fin=saturation temp. of vapor - T _r reference temperature defined in Eq. (15) - T temperature of surrounding air - T temp, difference between fin surface and surroundings - v initial temperature for quasilinearization - x vertical coordinate, see Fig. 1 - y horizontal coordinate, see Fig. 1 - coefficient of thermal expansion - emissivity - dimensionless parameter in Eq. (14) - ø _d heat flux of dry fin - ø _tot total heat flux of dry-wet fin - kinematic viscosity - Stefan-Boltzman coefficient - relative humidity of air     

A comparative study of five different PIV interrogation algorithms

Five different particle image velocimetry (PIV) interrogation algorithms are tested with numerically generated particle images and two real data sets measured in turbulent flows with relatively small particle images of size 1.0–2.5 pixels. The size distribution of the particle images is analyzed for both the synthetic and the real data in order to evaluate the tendency for peak-locking occurrence. First, the accuracy of the algorithms in terms of mean bias and rms error is compared to simulated data. Then, the algorithms ability to handle the peak-locking effect in an accelerating flow through a 2:1 contraction is compared, and their ability to estimate the rms and Reynolds shear stress profiles in a near-wall region of a turbulent boundary layer (TBL) at Re=510 is analyzed. The results of the latter case are compared to direct numerical simulation (DNS) data of a TBL. The algorithms are: standard fast Fourier transform cross-correlation (FFT-CC), direct normalized cross-correlation (DNCC), iterative FFT-CC with discrete window shift (DWS), iterative FFT-CC with continuous window shift (CWS), and iterative FFT-CC CWS with image deformation (CWD). Gaussian three-point peak fitting for sub-pixel estimation is used in all the algorithms. According to the tests with the non-deformation algorithms, DNCC seems to give the best rms estimation by the wall, and the CWS methods give slightly smaller peak-locking observations than the other methods. With the CWS methods, a bias error compensation method for the bilinear image interpolation, based on the particle image size analysis, is developed and tested, giving the same performance as the image interpolation based on the cardinal function. With the CWD algorithms, the effect of the spatial filter size between the iteration loops is analyzed, and it is found to have a strong effect on the results. In the near-wall region, the turbulence intensity varies by up to 4%, depending on the chosen interrogation algorithm. In addition, the algorithms computational performance is tested.     

Copper(I) Bromide: An Alternative Emitter for Blue‐Colored Flame Pyrotechnics

Copper(I) bromide was evaluated as an alternative emitter for blue flame pyrotechnic compositions. CuBr and CuCl emission spectra were recorded from a butane torch flame and compared. Cu(BrO₃)₂ was synthesized and used in pyrotechnic compositions as an oxidizer and the source for the generation of CuBr species. Pyrotechnic compositions, which contained copper and potassium bromates as oxidizers, were optimized for the generation of blue flames. The experimental data, including emission spectra of the flames, chromaticity coordinates, burning rates, luminous intensities, and sensitivity tests, were analyzed and compared.     

Prompt emission of nucleons in heavy-ion collisions

The mechanism of the production of quasifree promptly emitted particles in heavy ion collisions is studied within a sharp surface model. The particle production cross section is found to be rather low, ～1% of the total reaction cross section at energies slightly above the Coulomb barrier. Arguments on how to observe them in experiments are presented. Comparison between theoretical results and experimental data does not rule out the possibility of this reaction process.