Measurement of temperature fields in mixing vessels using optical topography

Experimental investigation of stirring processes require the measurement of temperature changes and concentration profiles in all the zones of the mixing volume. The conversion of simultaneous chemical reactions during the mixing process depends on the local temperature and concentration. The time-dependent temperature and concentration fields can be recorded for the entire mixing volume with the use of optical tomography and correlated with time. This technique offers the possibility of continuous measurement of temperature and concentration changes during the mixing process throughout the measurement volume. In the described investigations, optical tomography is used to examine the transport and equalization processes during mixing in stirred vessels.     

K-shell X-ray cross-section ratios for 1H, 4He and 6Li projectiles on targets from fluorine to titanium

Experimental K X-ray emission ratios have been measured for nine elements ranging from F to Ti (9 ? Z₂ ? 22) using ¹H⁺, and ⁶Li⁺ projectiles. The experimental ratios are in fair agreement with theoretical predictions for the velocity range studied, $\text{?}{}_{\mathrm{k}}\text{\$}\text{?}\text{1}$.     

Simple reinforcement for thin nephrostomy catheters

PURPOSE: Nephrostomy catheters are prone to kinking or damage because the thin, flexible silicone tube is too vulnerable against mechanical stress even when the proximal end is carefully fixed. We developed a simple method to reinforce the outside part of a thin catheter protruding from the skin. MATERIALS AND METHODS: We treated 7 children with nephrostomy catheters or ureteral stents with a diameter of 8F or smaller. After insertion a large plastic tube was wrapped around the small catheter, and fixed to the skin and to the peripheral collection system with adhesive tape. RESULTS: Handling of the catheters improved and there was less need for re-fixation. CONCLUSIONS: Thin nephrostomy catheters can be effectively protected by wrapping them into a larger, outer tube after insertion.     

Calibrated Models of Deicing Agent Solids, Pavement Texture, and Specific Conductivity of Highway Runoff

Field data and existing theory suggest that pavement texture governs the seasonal persistence of deicing agent solids and the storm scale variability of the specific conductivity of highway runoff. We measured precipitation, runoff, and specific conductivity for 50 storms over four deicing seasons at a highway drainage system in southeastern Massachusetts. An average pavement texture of 2.44?mm was measured and 5.17×105?kg of calcium magnesium acetate, salt, and premix applications was reported as well. Catchments and a depression storage layer model the highway drainage system, which routes hyetographs and slowly dissolving deicing agent solids to storm scale hydrographs and specific conductivity pollutographs. We equate the average pavement texture to the depression storage layer depth, which receives applied deicing agent solids, controls their dissolution during a storm, and governs their seasonal scale persistence. The observed average pavement texture, precipitation, and deicing agent applications yield first flush (storm scale) specific conductivity values in the depression storage layer that range from a winter maximum of 15?mS/cm to summer values two orders of magnitude lower. The winter maximum, or seasonal scale first flush of specific conductivity, would be lower for rougher pavement due to slower dissolution. The rougher pavement would also induce stronger persistence of deicing agent solids throughout the year, so that appreciable storm scale first flushes would occur in the summer.     

Silo Discharge: Measurement and Simulation of Dynamic Behavior in Bulk Solids

This paper deals with the experimental investigation and the numerical simulation of silo discharge processes, including dynamic interactions between the silo filling and the elastic silo walls. The discharge process is described by a system of nonlinear differential equations. Via the Finite Element Method (FEM) based on an EULERian reference frame, the deformation rate, the velocity field, the porosity, and the stress distribution can be calculated without the need of re‐meshing the FE‐grid. To compare simulation results with measured data, the numerical simulation examples are chosen to be similar to an experimental test‐silo of the Institute of Mechanical Process Engineering at the Technical University of Braunschweig. Optical measurement techniques are applied to investigate the flow profile, and load cells on the silo walls register the stress evolution, e.g., a stress peak (switch) moving from the outlet to the transition from hopper to shaft.     

Electronic energy loss of heavy ions colliding with atoms obtained from the harmonic oscillator model and from the shell-wise model

The quantal harmonic oscillator model and the shell-wise model in conjunction with a modified BK effective charge are used to calculate the electronic energy loss of heavy ions colliding with atoms. The stopping power near the stopping maximum obtained from the model calculations is compared with experimental data. It is shown that the experimentally well-known Z₁- and Z₂-oscillations of the electronic stopping cross sections are reproduced by the model calculations.     

How flat is an air-cleaved mica surface?

Muscovite mica is an important mineral that has become a standard substrate, due to its easy cleavage along the {001} planes, revealing a very flat surface that is compatible with many biological materials. Here we study mica surfaces by dynamic atomic force microscopy (AFM) operated in the non-contact mode (NC-AFM) under ultra-high vacuum (UHV) conditions. Surfaces produced by cleaving in UHV cannot be imaged with NC-AFM due to large surface charges; however, cleavage in air yields much less surface charge and allows for NC-AFM imaging. We present highly resolved NC-AFM images of air-cleaved mica surfaces revealing a rough morphology originating from a high density of nanometre-sized particles. Among these particles, we find regularly shaped structures indicating the growth of crystallites on the surface. The contamination layer cannot be removed by degassing in UHV; even prolonged heating at a temperature of 560?K under UHV conditions does not yield an atomically flat surface.     

Experiments and Computational Fluid Dynamics on Vapor and Gas Cavitation for Oil Hydraulics

A compressible Euler-Euler computational fluid dynamics (CFD) model for vapor, gas, and pseudo-cavitation in oil-hydraulic flows is presented. For vapor, the Zwart-Gerber-Belamri (ZGB) model is used and for gas cavitation, the Lifante model. The aim is to determine the empirical parameters within the cavitation models for hydraulic oil by comparing CFD results to experiments in a realistic valve. The cavitating flow is visualized and measured for numerous operating points. By degassing, states of pure vapor cavitation are generated. The major findings are: (1) large eddy simulation turbulence modeling is essential, (2) vapor cavitation in mineral oil can be simulated very well with the ZGB model using the determined parameter, and (3) gas cavitation model provides useful results although not all details can be reflected and its scope is limited.     

Bifunctional Reagents for Formylglycine Conjugation: Pitfalls and Breakthroughs

Formylglycine-generating enzymes specifically oxidize cysteine within the consensus sequence CxPxR to C^α-formylglycine (FGly). This noncanonical electrophilic amino acid can subsequently be addressed selectively by bioorthogonal hydrazino-iso-Pictet-Spengler (HIPS) or Knoevenagel ligation to attach payloads like fluorophores or drugs to proteins to obtain a defined payload-to-protein ratio. However, the disadvantages of these conjugation techniques include the need for a large excess of conjugation building block, comparably low reaction rates and limited stability of FGly-containing proteins. Therefore, functionalized clickable HIPS and tandem Knoevenagel building blocks were synthesized, conjugated to small proteins (DARPins) and subsequently linked to strained alkyne-containing payloads for protein labeling. This procedure allowed the selective bioconjugation of one or two DBCO-carrying payloads with nearly stoichiometric amounts at low concentrations. Furthermore, an azide-modified tandem Knoevenagel building block enabled the synthesis of branched PEG linkers and the conjugation of two fluorophores, resulting in an improved signal-to-noise ratio in live-cell fluorescence-imaging experiments targeting the EGF receptor.     

Entwicklung einer Methode zur nichtinvasiven Messung des Absolutdrucks in teiltransparenten Gebinden mit karbonisierten Getränken

A non-invasive optical measurement technique for food analysis is presented, which allows for a reliable determination of the absolute pressure in beverage bottles with carbonated contents. The method uses a tunable laser diode with an emission wavelength around 2004 nm to record three to four absorption lines of CO₂ and evaluates the pressure broadening of the lines proportional to the absolute pressure. With the developed measuring method, a standard deviation of repeated absolute pressure measurements of up to 5.5 bar of less than 50 mbar could finally be achieved in field measurements on sealed soft drink bottles made of PET.