Quantitative analysis of hydrogen in thin films using Time-of-Flight Elastic Recoil Detection Analysis

Determination of atomic concentrations in thin films is one of the key problems in materials science. Time-of-Flight Elastic Recoil Detection Analysis is a powerful method for depth profiling of light and medium mass elements in near surface layers of material. However, due to poor detection efficiency those spectrometers are not commonly used for hydrogen analysis. We have performed some improvements in order to increase detection efficiency and to make spectrometer more suitable for hydrogen analysis. The spectrometer performance was tested on amorphous Si samples implanted with H⁻ and D⁻ and hydrogenised Si standard reference sample. Sensitivity for hydrogen in silicon matrix was found to be several tens of ppm with a surface depth resolution of ~ 15 nm.     

Microwave-assisted synthesis of carboxymethylcellulose – based polymeric surfactants

Summary Carboxymethylcellulose (CMC, DS_CM = 1) was partially hydrophobized in order to prepare polymeric surfactants by the transesterification reaction using the methyl ester of the fatty acid complex of rapeseed oil (MERO). The chemical modification was performed in different reaction media (i) DMF/TSA and (ii) H₂O/DMF with and without K₂CO₃ as catalyst, at various reaction conditions and using microwave radiation with controlled power as heating source. The obtained MERO-hydrophobized CMC (MH-CMC) comprising mixed fatty acyl esters were characterized by FT-IR and NMR spectroscopic techniques, which indicated a very low degree of esterification (DS < 0.1). The derivatives showed, in spite of moderate surface tension-lowering effects, excellent emulsifying activity for ‘oil in water’ type emulsions as well as good performance properties including washing power and antiredeposition efficiency. The results suggested that surface-active MH-CMC derivatives can be prepared under microwave heating at reaction times in the range of several minutes, what is a great advantage in comparison to transesterification reactions lasting up to 6 h at conventional heating. The novel CMC esters represent biodegradable polymeric surfactants with potential applications in manufacture of consumer products and in industrial processes.     

Development of a time-of-flight spectrometer at the Ruder Boškovi? Institute in Zagreb

A new TOF telescope has been constructed for thin film and surface analysis. The timing system consists of two electrostatic mirror type detectors of Busch design. The detection efficiency of timing stations for very light ions was significantly improved using DLC (diamond like carbon) foils coated with LiF instead of the conventionally used carbon foils. Ion energy is measured by a 300 mm² ULTRA ion-implanted silicon detector. For the ERDA measurements with heavy and energetic ion beams, a time-of-flight (TOF) spectrometer is positioned at 37.5°. Spectrometer can be easily moved to 120° backward angle for time-of-flight RBS analysis with low energy beam of light ions. Positioning and fine adjustments of sample orientation are performed with a motorized sample stage. The same spectrometer can be also installed at the ion microprobe scattering chamber for 3D elemental imaging.     

DRYING RESEARCH AND DEVELOPMENT IN CZECHOSLOVAKIA

This paper provides general information on drying R 6D activities in Czechoslovakia. This survey report lists the main topics in drying according to individual industrial sectors in which drying plays an important role. Drying R 6D carried out in Czechoslovak Universities is also cited. The paper includes an extensive list of references, mainly proceedings of national drying conferences, symposia, and meetings     

Constrained simulations of flow in haemodynamic devices: towards a computational assistance of magnetic resonance imaging measurements

Cardiovascular diseases, mostly related to atherosclerosis, are the major cause of death in industrial countries. It is observed that blood flow dynamics play an important role in the aetiology of atherosclerosis. Especially, the blood velocity distribution is an important indicator for predisposition regions. Today magnetic resonance imaging (MRI) delivers, in addition to the morphology of the cardiovascular system, blood flow patterns. However, the spatial resolution of the data is slightly less than 1 mm and owing to severe restrictions in magnetic field gradient switching frequencies and intensities, this limit will be very hard to overcome. In this paper, constrained fluid dynamics is applied within the smoothed particle hydrodynamics formalism to enhance the MRI flow data. On the one hand, constraints based on the known volumetric flow rate are applied. They prove the plausibility of the order of magnitude of the measurements. On the other hand, the higher resolution of the simulation allows one to determine in detail the flow field between the coarse data points and thus to improve their spatial resolution.     

The Relevance of Physico-Chemical Properties and Protein Corona for Evaluation of Nanoparticles Immunotoxicity—In Vitro Correlation Analysis on THP-1 Macrophages

Alongside physiochemical properties (PCP), it has been suggested that the protein corona of nanoparticles (NPs) plays a crucial role in the response of immune cells to NPs. However, due to the great variety of NPs, target cells, and exposure protocols, there is still no clear relationship between PCP, protein corona composition, and the immunotoxicity of NPs. In this study, we correlated PCP and the protein corona composition of NPs to the THP-1 macrophage response, focusing on selected toxicological endpoints: cell viability, reactive oxygen species (ROS), and cytokine secretion. We analyzed seven commonly used engineered NPs (SiO₂, silver, and TiO₂) and magnetic NPs. We show that with the exception of silver NPs, all of the tested TiO₂ types and SiO₂ exhibited moderate toxicities and a transient inflammatory response that was observed as an increase in ROS, IL-8, and/or IL-1β cytokine secretion. We observed a strong correlation between the size of the NPs in media and IL-1β secretion. The induction of IL-1β secretion was completely blunted in NLR family pyrin domain containing 3 (NLRP3) knockout THP-1 cells, indicating activation of the inflammasome. The correlations analysis also implicated the association of specific NP corona proteins with the induction of cytokine secretion. This study provides new insights toward a better understanding of the relationships between PCP, protein corona, and the inflammatory response of macrophages for different engineered NPs, to which we are exposed on a daily basis.     

Thermal Characterization of Metakaolin-Based Geopolymer

Thermal characterization of geopolymer powder was investigated at room and elevated temperatures. The physical, chemical and mass change with respect to various temperatures have been studied. The physical properties such as density, porosity, and particle size were analyzed in geopolymer powder. The chemical and phase compositions were determined by x-ray fluorescence. The surface images of solid blocks of geopolymer were examined at room and elevated temperatures using scanning electron microscopy. Thermal expansion, shrinkage, and mass loss behavior towards the elevated temperatures were investigated by differential scanning calorimetry (DSC). The endothermic peak arising in the DSC curve is due to evaporation of water, chemical, gases and weight loss.     

Ambient air quality for the territory of the Czech Republic in 1996-1999 expressed by three essential factors

A new method for spatial interpretation and visualisation of measured air quality data developed and introduced in 1998 is used for ambient air quality assessment in the Czech Republic. The data from a countrywide air quality monitoring network is collated into the least possible number of factors describing the overall air quality in 1996-1999. The factors identified as 'ambient air pollution', 'ground-level ozone' and 'wet atmospheric deposition' represent three different aspects of ambient air quality and their impact on receptors' evaluation. The monitoring stations are classified for each factor using five categories clearly distinguishing the sites over the Czech Republic territory within the 'best-worst' scale range. The results are presented in maps with spot symbols produced in Arc/View system. The problem areas within the country are identified clearly for each factor. The air quality picture differs considerably for the respective factors within one calendar year. Categorisation of each factor for the entire period under review, however, remains strikingly similar, indicating that in spite of partial improvement and some decreases in air pollutant concentration, the problem areas have remained more or less the same for each factor. Comparison of all three factors shows that the southern part of the country is in a certain simplification very clean as to the 'ambient air pollution' and 'wet atmospheric deposition' factors, while it is impacted as to the 'ground-level ozone' factor. In contrast, the northern part of the country impacted as to the 'ambient air pollution' along with the 'wet atmospheric deposition' and 'ground-level ozone' factors at the higher elevations.     

Molecular dynamics of oligopeptides. 1. The use of long trajectory and high temperature data for determination of statistical weight of conformational substates

The purpose of this study was to assess the accuracy of chest x-ray (CXR) interpretation in the diagnosis of pneumocystis carinii pneumonia (PCP), bacterial pneumonia (BP), and pulmonary tuberculosis (TB) in human immunodeficiency virus (HIV)-positive patients and to identify the frequency with which these infections mimic one another radiographically. The admitting CXRs of 153 HIV-positive patients with laboratory proven BP (n = 71), PCP (n = 73), and TB (n = 9) and those of 10 HIV-positive patients with no active disease were reviewed retrospectively and independently by three radiologists who were blinded to clinical and laboratory data. Median percent accuracies were as follows: TB, 84%; PCP, 75%; BP, 64%; and no active disease, 100%. Fifteen of 153 cases (9.8%) were shown to mimic other infections radiographically. A confident and accurate diagnosis can be made radiographically in the majority of cases of PCP, BP, and TB in HIV-positive patients at the time of hospitalization. In approximately 10% of cases, these infections may mimic one another radiographically.     

Note on the principle of stationary phase

The principle of stationary phase as enunciated by Kelvin [1] in 1887 concerns the approximate evaluation of an integral of a rapidly fluctuating function. The well-known formula is derived on the tacit assumption of the amplitude function ?(x) being non-zero at the isolated stationary point ? of the phase function ?(x). The present note points out that the vanishing of ?(x) at this point alters the order of approximation. The significant contribution to the integral comes in this case from the first non-vanishing even order derivative of ?(x) at x = ? and the corresponding formula for the approximate value has been worked out. The formula has been further generalized for the case when the first non-vanishing derivatives of ? and ? are ?ⁿ(α) and ?^m(α), respectively, m, n being both positive integers.