Mechanical and Fatigue Properties of Diamond-Reinforced Cu and Al Metal Matrix Composites Prepared by Cold Spray.

Diamond-reinforced metal matrix composites (DMMC) prepared by cold spray are emerging materials simultaneously featuring outstanding thermal conductivity and wear resistance. In our paper, their mechanical and fatigue properties relevant to perspective engineering applications were investigated using miniature bending specimens. Two different diamond mass concentrations (20 and 50%) embedded in two metal matrices (Al-lighter than diamond, Cu-heavier than diamond) were compared with the respective cold-sprayed pure metals, as well as bulk Al and Cu references. The pure Al, Cu coatings showed properties typical for cold spray deposits, i.e., decreased elastic moduli (50 GPa for Al, 80 GPa for Cu), limited ductility (< 1 × 10-3) and low fracture toughness (3.8 MPa·m0.5 for Al, 5.6 MPa·m0.5 for Cu) when compared to the bulks. Significantly improved properties (strain at fracture, ultimate strength, fatigue crack growth resistance, fracture toughness) were then observed for the produced DMMC. The improvement can be explained by a combination of two factors: changes in the properties of the metallic matrix triggered by the reinforcement particles peening effect and stress redistribution due to the particles presence.

The effect of repeated passaging on the susceptibility of human proximal tubular HK-2 cells to toxic compounds.

The human proximal tubular HK-2 cell line is an immortalized cell line commonly used for studying proximal tubular toxicity. Even as their use is presently increasing, there unfortunately are no studies focused on functional changes in HK-2 cells associated with passaging. The aim of the present study, therefore, was to evaluate the functional stability of HK-2 cells during 13 weeks of continuous passaging after 6 and 24 h of treatment with model nephrotoxic compounds (i.e., acetaminophen, cisplatin, CdCl(2)). Short tandem repeat profile, the doubling time, cell diameter, glutathione concentration, and intracellular dehydrogenase activity were measured in HK-2 cells at each tested passage. The results showed that HK-2 cells exhibit stable morphology, cell size, and cell renewal during passaging. Mean doubling time was determined to be 54 h. On the other hand, we observed a significant effect of passaging on the susceptibility of HK-2 cells to toxic compounds. The largest difference in results was found in both cadmium and cisplatin treated cells across passages. We conclude that the outcomes of scientific studies on HK-2 cells can be affected by the number of passages even after medium-term cultivation and passaging for 13 weeks.

Achromatic Non-Interferometric Single Grating Neutron Dark-Field Imaging.

We demonstrate a simple single grating beam modulation technique, which enables the use of a highly intense neutron beam for differential phase and dark-field contrast imaging and thus spatially resolved structural correlation measurements in full analogy to interferometric methods. In contrast to these interferometric approaches our method is intrinsically achromatic and provides unprecedented flexibility in the choice of experimental parameters. In particular the method enables straight forward application of quantitative dark-field contrast imaging in time-of-flight mode at pulsed neutron sources. Utilizing merely a macroscopic absorption mask unparalleled length scales become accessible. We present results of quantitative dark-field contrast imaging combining microstructural small angle scattering analyses with real space imaging for a variety of materials.

Transient increase in cellular dehydrogenase activity after cadmium treatment precedes enhanced production of reactive oxygen species in human proximal tubular kidney cells.

Cadmium is a heavy metal causing toxicity especially in kidney cells. The toxicity is linked also with enhanced oxidative stress leading to cell death. On the other hand, our recent experiments have shown that an increase of total intracellular dehydrogenases activity can also occur in kidney cells before declining until cell death. The aim of the present study, therefore, was to evaluate this transient enhancement in cell viability after cadmium treatment. The human kidney HK-2 cell line was treated with CdCl(2) at concentrations 0-200 microM for 2-24 h and intracellular dehydrogenase activity was tested. In addition, we measured reactive oxygen species (ROS) production, glutathione levels, mitochondrial membrane potential, and C-Jun-N-terminal kinase (JNK) activation. We found that significantly increased dehydrogenase activity could occur in cells treated with 25, 100, and 200 microM CdCl(2). Moreover, the results showed an increase in ROS production linked with JNK activation following the enhancement of dehydrogenase activity. Other tests detected no relationship with the increased in intracellular dehydrogenase activity. Hence, the transient increase in dehydrogenase activity in HK-2 cells preceded the enhancement of ROS production and our finding provides new evidence in cadmium kidney toxicity.

Intergranular Strain Evolution During Biaxial Loading: A Multiscale FE-FFT Approach.

Predicting the macroscopic and microscopic mechanical response of metals and alloys subjected to complex loading conditions necessarily requires a synergistic combination of multiscale material models and characterization techniques. This article focuses on the use of a multiscale approach to study the difference between intergranular lattice strain evolution for various grain families measured during in situ neutron diffraction on dog bone and cruciform 316L samples. At the macroscale, finite element simulations capture the complex coupling between applied forces and gauge stresses in cruciform geometries. The predicted gauge stresses are used as macroscopic boundary conditions to drive a mesoscale full-field elasto-viscoplastic fast Fourier transform crystal plasticity model. The results highlight the role of grain neighborhood on the intergranular strain evolution under uniaxial and equibiaxial loading.

Measurement of thermal properties of thin films up to high temperatures--pulsed photothermal radiometry system and Si-B-C-N films.

A new arrangement of two-detector pulsed photothermal radiometry measurement system has been developed enabling temperature dependence measurement of thermal properties of thin films up to high temperatures. Only a few methods are available in this temperature range for thin films' thermal properties investigation, but there is a need for their knowledge in the fields of high-temperature electronics and high-speed machining. The present system enables simultaneous determination of the thin film effusivity, thermal conductivity, and volumetric specific heat in the temperature range from room temperature to 600 °C. The samples are placed in a vacuum chamber. The temperatures in the system were verified by an independent measurement and the system was tested on known bulk samples. Advantages and shortcomings of the method when used at higher temperatures and in the vacuum are described and discussed. Furthermore, Si-B-C-N thin films were studied. These amorphous ceramic materials possess an interesting set of mechanical and thermal properties. In particular, the films of the investigated chemical composition exhibit an excellent thermal stability at temperatures of up to 1700 °C. In the studied temperature range, from 20 to 600 °C, the thermal conductivity increased with increasing temperature from 1.72 to 1.89 W m(-1) K(-1) and volumetric specific heat increased from 2.65 to 3.76 × 10(6) J m(-3) K(-1).

Lactate stress test in the diagnosis of mitochondrial myopathy.

The aim of the study was to determine the sensitivity and specificity of the lactate stress test in the detection of mitochondrial myopathies. Thirty one healthy subjects, 10 patients with non-mitochondrial myopathy and 26 patients with mitochondrial myopathy underwent lactate stress testing at a standardized workload of 30 W during 15 min on a bicycle ergometer. Lactate was determined before the exercise (R1), 5, 10, 15 min after starting the exercise (S5, S10, S15) and 15 min after finishing the exercise (R2). A result was interpreted as pathologic if more than two of the five lactate values were above the corresponding upper reference limits. The upper reference limits for the venous lactate at R1, S5, S10, S15 and R2 were 1.9, 2.0, 2.1, 2.0 and 1.7 mmol/l respectively. The lactate stress test was pathologic in 1/10 of the non-mitochondrial myopathies and in 18/26 of the mitochondrial myopathies. The sensitivity of the lactate stress test was 69%. The specificity of the test was 90%. In conclusion, the lactate stress test proved to be helpful for evaluating the integrity of the oxidative metabolism in the majority of patients with mitochondrial myopathy.

[Determination of forced expiratory volume (FEV 1) and maximal peak expiratory flow within the scope of routine diagnosis in general practice]. / Bestimmung des Atemstosses (FEV 1) und des maximalen Atemstroms (PEF) im Rahmen der Basisdiagnostik in der Allgemeinpraxis.

In 5 Viennese general practice offices we investigated patients by spirometry with the following indications: differential diagnosis of dyspnea; every 3rd smoker of more than 10 cigarettes a day (including asymptomatic ones); cough and nasal disorders of more than 4 weeks duration; indicative physical findings (cyanosis or auscultation). The sample control group was matched for age and gender and did not have any symptoms characteristic of the indication group. Nevertheless a spirometric test was also carried out in these patients. A total of 212 patients were examined in 4673 consultations on 202 workdays in the 5 offices. In the group of 109 patients 62 (56.9%) had dyspnea and/or positive signs on auscultation. Of these 62 patients 39 (62.9%) had 1 or more positive findings either from PEF or FEV 1 or both. There were significantly more referrals for X-rays in case of abnormal lung function. The control group of 103 obviously healthy persons in particular showed a significantly higher number of abnormal PEF values than expected (31 persons, 30.1%).

[Coronary arteritis and its clinical significance]. / Koronární arteritis a její klinický význam.

The authors submit a report on a 47-year-old man with the syndrome of angina pectoris and history of myocardial infarction who died after a revascularization operation of the heart from left ventricular insufficiency. On necropsy extensive arteritis of the coronary vessels with aortitis was revealed and with arteritis of the small intramyocardial and lienal arteries and arteries in the renal pelvis. They describe in detail the histological finding on the blood vessels, and consistent with some data in the literature, they assume that this disease forms a separate unit. It must be considered in particular in middle-aged men who have signs of coronary ischaemia and risk factors suggesting atherosclerosis, not occur in the case-history.

[Long-term survival after palliative embolization of kidneys affected by tumors]. / Dlouhodobé prezívání po paliativní embolizaci ledviny postizené nádorem.

Based on their own experience and data in the literature, the authors recommend to use also in future palliative embolization of the kidney as part of comprehensive treatment of patients with inoperable tumours of the kidney. They describe their experience with a group of 20 patients. In one female patient after palliative embolization an unusually favourable effect was observed with macroscopic disappearance of the tumour and affection of the pleura, associated with prolonged survival.