Elektrokinetische untersuchungen von chemiefasern

Electrokinetic parameters like the electroosmotic current (Q_c) and the electrokinetic potential (ζ) of fibres depend strongly on masses and structures of the investigated samples. The influence of these parameters was determined using fibres of polyamide, polyester, and polyacrylonitrile. It was found (a) that it is not possible to measure the true zeta-potential by the electroosmotic method and (b) that a determination of the influence of these parameters is not necessary for making a relative comparison of the zeta-potential of different fibres.     

Investigations of electrokinetic properties of dyed polyamide fibres

Changes of the electrokinetic flow intensity Q_v and the zeta potential for polyamide fibres colourless and dyed with Polan dyes were analyzed. Essential differences in determined quantities were found for fibres dyed with dyes of different steric structure.     

Beckwith-Wiedemann syndrome: difficulties with prenatal diagnosis

The characteristics of the midsole were examined in four pairs of running shoes by a materials test. The variables of interest were the peak acceleration, time to peak acceleration and the kinetic energy absorbed. Ten subjects then ran at a recreational jogging pace (3.5 ms-1) barefoot and in the shoes. An accelerometer secured to the lower tibia was used to measure the peak acceleration and time to peak acceleration associated with footstrike. Subjects were also videoed and a kinematic analysis was undertaken at the knee and ankle joints. The results from the materials test showed that the shoes differed in their midsole characteristics, however, no significant differences (P > 0.05) were observed in the peak acceleration and time to peak acceleration during running in shoes. These variables were significantly greater in the barefoot running condition (P < 0.05), as compared with running in shoes. Small and subtle kinematic differences were observed between the barefoot and shoe conditions. It appears that the differences observed between the shoes in the materials test were not sufficient to elicit the kinematic changes observed between the barefoot and shoe conditions. It is suggested that runners operate within a 'kinetic bandwidth' when responding to impact stresses.     

Septic myocardial aneurysm in mitral valve endocarditis. Clinical and pathological-anatomical findings

HISTORY AND CLINICAL FINDINGS: A 68-year-old woman was hospitalized because of fever and tiredness for 3 months. Her general condition was clearly impaired. She had a mild fever of 38.5 degrees C and on auscultation a 3/6 systolic murmur, maximal parasternally in the 3rd intercostal space, transmitted to the apex. There were distant rales over both lungs, the neck veins were distended and there was ankle oedema. INVESTIGATIONS: C-reactive protein was raised to 17.3 mg/dl (normal up to 0.9 mg/dl), WBC count 19,300/microliter. beta-haemolysing streptococcus (S. agalactiae) was grown in the blood culture. The ECG showed sinus tachycardia (rate of 98/min) and transthoracic echocardiography demonstrated a small pericardial, enlarged ventricles, marked mitral regurgitation and a large vegetation on the posterior mitral leaflet, as well as a 3 x 4 cm mass in the posterior wall of the ventricle, originating from the posterior mitral valve ring and communicating with the vegetation on the mitral valve. The posterior mitral leaflet was perforated. TREATMENT AND COURSE: As endocarditis of the mitral valve with a complicated course was suspected-abscess of the posterior mitral valve ring and septic myocardial aneurysm with associated pericarditis and haemodynamically insignificant effusion-she was transferred to the intensive care unit where she died suddenly of circulatory arrest only 30 min after transfer. Autopsy confirmed the echocardiographic findings. CONCLUSION: Paravalvular abscess in the course of mitral valve endocarditis is rare, but should be looked for at transthoracic echocardiography so that any necessary surgical intervention can be undertaken early.     

Visual‐Interactive Preprocessing of Multivariate Time Series Data

Pre‐processing is a prerequisite to conduct effective and efficient downstream data analysis. Pre‐processing pipelines often require multiple routines to address data quality challenges and to bring the data into a usable form. For both the construction and the refinement of pre‐processing pipelines, human‐in‐the‐loop approaches are highly beneficial. This particularly applies to multivariate time series, a complex data type with multiple values developing over time. Due to the high specificity of this domain, it has not been subject to in‐depth research in visual analytics. We present a visual‐interactive approach for preprocessing multivariate time series data with the following aspects. Our approach supports analysts to carry out six core analysis tasks related to pre‐processing of multivariate time series. To support these tasks, we identify requirements to baseline toolkits that may help practitioners in their choice. We characterize the space of visualization designs for uncertainty‐aware pre‐processing and justify our decisions. Two usage scenarios demonstrate applicability of our approach, design choices, and uncertainty visualizations for the six analysis tasks. This work is one step towards strengthening the visual analytics support for data pre‐processing in general and for uncertainty‐aware pre‐processing of multivariate time series in particular.     

On the temperature control in a microstructured packed bed reactor for methanation of CO/CO2 mixtures

Microreactor technology is widely used for process intensification and is essential for fast and strongly exothermic reactions exhibiting mass and heat transfer limitations. In the scope of the MINERVE Power‐to‐Gas project, sponsored by KIC InnoEnergy from 2012 to 2015, a micro packed bed reactor was developed for conversion of syngas containing CO₂ into methane. This work focuses on heat removal and temperature control in a manufactured device using syngas throughputs less than 1.4 Nm³/h (10% CO, 7% CO₂, H₂/C = 4) while examining the cooling potential of different cooling fluids, e.g., air, steam and water. © 2016 American Institute of Chemical Engineers AIChE J, 63: 120–129, 2017     

A function for α-tocopherol: Stabilization of the microsomal membrane from radical attack during TPNH-dependent oxidations

Events accompanying electron transport in the membrane fraction of liver and other tissues have led us to propose a specific function for α-tocopherol based on a sequence of biochemical changes we observed to occur in these membranes and on pertinent information from other laboratories. The activity of a membrane-bound enzyme system (TPNH oxidase) which involves transport of electrons from substrate to oxygen, has been shown to promote simultaneous formation of peroxide functions on the β position polyunsaturated fatty acids (PUFA) of phospholipids in the membrane. The phospholipid peroxides then undergo a chain cleavage reaction producing phospholipids containing a variety of carbonyl moieties in the β position. The process results in marked alteration of the membrane structure. During the overall reaction α-tocopherol present in the membrane is converted to a compound more polar than tocopheryl quinone and the conversion is dependent on the same enzymic factors promoting the phospholipid alterations. The membrane alteration process is enhanced in microsomes from animals fed diets containing relatively high levels of PUFA or diets low in α-tocopherol, and is diminished by low levels of dietary PUFA or relatively high levels of α-tocopherol. The experimental data indicate that enzymic electron transport associated with TPNH oxidation by the microsomal membrane involves free radical functions. The latter apparently can promote extensive peroxidative alterations of phospholipids that result in structural changes in the membrane unless adequate α-tocopherol is present in this organelle. This system appears to be part of the microsomal drug metabolizing system.     

Formation of By‐products in Pure and Aqueous Acrylic Acid – Kinetic Measurements and Formation Mechanisms

During acrylic acid (AA) storage, a quality loss occurs due to the formation of by‐products such as diacrylic acid (DiAA), triacrylic acid (TriAA), and higher oligomers. This problem intensifies in the presence of water since the formation rate of oligomers increases and further by‐products such as 3‐hydroxypropionic acid (3‐HPA) and 3‐hydroxydiacrylic acid (3‐HDiAA) are formed. However, water is often essential during storage and transport to raise the flash point or reduce the melting point. In this work, the formation kinetics are investigated for all mentioned components in pure and aqueous AA. The formation mechanisms of 3‐HPA and 3‐HDiAA are assumed as acid‐catalyzed ester hydrolyses of DiAA or TriAA. The introduced reactions are modeled with the measured kinetic data in order to confirm the proposed reactions.     

Low-energy arc welding with gas shielding – the effect of material and technological conditions on joint quality and the emission of impurities in the workplace

Connecting modern extra-lightweight materials requires the use of technology which cannot be provided by traditional gas-shielded welding methods. It is, therefore, necessary to develop variants of the arc welding method, which would deliver a very small amount of heat to the material but which would still ensure that the resulting joints would be tough. coldArc welding is a modification of the MIG/MAG method, which meets those requirements. With this method, all interventions in the process are made directly at the source of the power supply, without mechanical intervention in the feeding of the solder wire. As such, it is possible to use standard holders, and this method may also be successfully used in manual welding.     

Modeling and Simulation of an Integrated Micro Packed Bed Reactor-Heat Exchanger Configuration for Direct Dimethyl Ether Synthesis

The application of an integrated micro packed bed reactor-heat exchanger for highly exothermic syngas conversion to dimethyl ether was investigated by numerical simulation. A three-dimensional pseudo-homogeneous model was developed to describe concentration and temperature distributions inside a single reaction slit. The model was adopted at low Reynolds numbers (small catalyst particles and long residence times). The simulation results reveal that the micro packed reaction slit is close to isothermal, and a negligible temperature gradient is predicted also for a doubling of the critical reaction slit dimension, i.e. the reaction slit height. The flow in the reaction slit was modelled by Brinkman??s equation and it was found that the pressure drop in wide range of gas velocity was not significant. The reactor simulation showed good agreement with experimental results and could be further developed to assess the potential of microstructured packed bed reactors to intensify large-scale industrial processes.