Towards the understanding of the gold interaction with AIII-BV semiconductors at the atomic level.

AIII-BV semiconductors have been considered to be a promising material for decades in overcoming the limitations of silicon semiconductor devices. One of the important aspects within the AIII-BV semiconductor technology is gold-semiconductor interactions on the nanoscale. We report on the investigations into the basic chemical interactions of Au atoms with AIII-BV semiconductor crystals by the investigation of the nanostructure formation in the process of thermally-induced Au self-assembly on various AIII-BV surfaces by means of atomically resolved High Angle Annular Dark Field (HAADF) Scanning Transmission Electron Microscopy (STEM) measurements. We have found that the formation of nanostructures is a consequence of the surface diffusion and nucleation of adatoms produced by Au induced chemical reactions on AIII-BV semiconductor surfaces. Only for InSb crystals we have found that there is efficient diffusion of Au atoms into the bulk, which we experimentally studied by Machine Learning HAADF STEM image quantification and theoretically by Density Functional Theory (DFT) calculations with the inclusion of finite temperature effects. Furthermore, the effective number of Au atoms needed to release one AIII metal atom has been estimated. The experimental finding reveals a difference in the Au interactions with the In- and Ga-based groups of AIII-BV semiconductors. Our comprehensive and systematic studies uncover the details of the Au interactions with the AIII-BV surface at the atomic level with chemical sensitivity and shed new light on the fundamental Au/AIII-BV interactions at the atomic scale.

Effect of the type of reducing agents of silver ions in interpolyelectrolyte-metal complexes on the structure, morphology and properties of silver-containing nanocomposites.

The objective of this work is to study the peculiarities of structural organization, morphology, thermomechanical, electrical and antimicrobial properties of nanocomposites based on pectin-polyethyleneimine interpolyelectrolyte complexes and silver nanoparticles in dependence on the type of reducing agent being applied for chemical reduction of silver ions in the interpolyelectrolyte-metal complexes. The average size of Ag nanoparticles is shown to be increased with decreasing of the activity of reducing agent (E0) and equals to 3.8 nm, 4.3 nm, and 15.8 nm, respectively, when engaging sodium borohydride (-1.24 V), hydrazine (-1.15 V) and ascorbic acid (-0.35 V). Moreover, it was found that the crystallite size of Ag nanoparticles also had the smallest value for nanocomposites obtained involving NaBH4 as reducing agent. Ag-containing nanocomposites prepared by reduction of silver ions in interpolyelectrolyte-metal complexes while applying a range of reducing agents are characterized by different electrical properties and polymer matrix' glass transition temperature. The influence of silver nanoparticles' size incorporated in the polymer matrix on the antimicrobial activity of nanocomposites has been established. The inhibition zone diameter of Staphylococcus aureus and Escherichia coli was higher for nanocomposites obtained using sodium borohydride and hydrazine compared to nanocomposites where ascorbic acid was used as the reducing agent.

Characterization of the µ and P phase precipitates in the CMSX-4 single crystal superalloy.

A combination of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and scanning-transmission electron microscopy (STEM) using high-angle annular-dark-field (HAADF) imaging, focussed ion beam- scanning electron microscopy (FIB-SEM) tomography, selected area electron diffraction with beam precession (PED), as well as spatially resolved energy-dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS), was used to investigate topologically close-packed (TCP) phases, occurring in the CMSX-4 superalloy subjected to high temperature annealing and creep deformation. Structural and chemical analyses were performed to identify the TCP phases and provide information concerning the compositional partitioning of elements between them. The results of SEM and FIB-SEM tomography revealed the presence of merged TCP particles, which were identified by TEM and PED analysis as coprecipitates of the µ and P phases. Inside the TCP particles that were several micrometres in size, platelets of alternating µ and P phases of nanometric width were found. The combination of STEM-HAADF imaging with spatially resolved EDS and EELS microanalysis allowed determination of the significant partitioning of the constituent elements between the µ and P phases.

TEM, HRTEM, electron holography and electron tomography studies of gamma' and gamma'' nanoparticles in Inconel 718 superalloy.

The aim of the study was the identification of gamma' and gamma'' strengthening precipitates in a commercial nickel-base superalloy Inconel 718 (Ni-19Fe-18Cr-5Nb-3Mo-1Ti-0.5Al-0.04C, wt %) using TEM dark-field, HRTEM, electron holography and electron tomography imaging. To identify gamma' and gamma'' nanoparticles unambiguously, a systematic analysis of experimental and theoretical diffraction patterns were performed. Using HRTEM method it was possible to analyse small areas of precipitates appearance. Electron holography and electron tomography techniques show new possibilities of visualization of gamma' and gamma'' nanoparticles. The analysis by means of different complementary TEM methods showed that gamma'' particles exhibit a shape of thin plates, while gamma' phase precipitates are almost spherical.

The changes in protein fraction of milk subjected to vibration.

This paper presents a model study into the effect of vibration on the changes in the nitrogen compound system of whole milk. It was found that milk protein destabilization increases with an increase in vibration frequency. Moreover, it was observed that in skimmed milk obtained from whole milk subjected to vibration, the total and dissolved nitrogen contents and the casein dehydration degree tended to decrease while the NPN+PPN level increased.

The effect of vibration frequency on changes in the salt system of milk.

This paper presents a model study into the effect of varied frequencies (10-60 Hz) of vertical and horizontal vibrations at a constant acceleration of 1g for 60-min. exposures on the changes in the salt system of milk. It was found that the tendencies of changes in the salt system of milk under vertical and horizontal vibrations are similar and are determined by the applied frequency. Their intensity increased with an increase in vibration frequency.

Vibrations in milk transportation.

During transport of milk in three-cell tank truck, the vibrating acceleration ranged generally on the level of 0.5 to 2g (0.5 to 20 m/s2) at the vibrating frequency 2 to 60 Hz. The vibration increased proportionally to the driving speed of tank truck, being dependent on the type and surface condition of road and the efficiency of space filling in the container, with lower vibration levels at lower filling.

Influence of vibrations on fat-phase of milk.

Model studies are presented on the influence of vertical and horizontal vibrations of different frequency (10 to 60 Hz), constant acceleration 1 g, and constant exposition time 60 min on changes in the lipid fraction of milk. It was found that the changes in the examined characteristics of milk fat were dependent on and intensified with the frequency.

Excitatory and inhibitory responses of the ongoing sympathetic discharge in single renal neurons to liminal stimulation of aortic C-fibres in the rabbit.

Excitatory and inhibitory responses of sympathetic discharge were recorded in single renal postganglionic neurons of rabbits anaesthetized with urethane and chloralose. The animals were vagotomized and had transected aortic nerves. Responses were elicited by single volleys in the aortic C-fibres. Excitatory responses consisted in short-lasting increase in the rate of ongoing sympathetic discharge and were followed by inhibitory responses. Excitatory effects together with inhibitory responses were seen in 68% of units (19/28). Only excitatory effects appeared in 2 neurons (7.1%) and only inhibitory effects in 7 neurons (25%). In renal neurons exhibiting both effects, the excitatory responses appeared after latency of 172 +/- 8 ms (x +/- S.D.) and had duration of 64 +/- 11 ms. Inhibitory effects had latency o f 257 +/- 10 ms and their duration amounted to 265 +/- 22 ms. In more than half of recordings the excitatory responses were separated from the inhibitory effects by discharge lasting 33 +/- 4 ms. Significant correlations between latencies of excitatory and inhibitory responses and between duration of excitatory and latency of inhibitory responses suggest interaction between both effects. Increase in the number of afferent volleys (1 through 5) evoked relatively small changes in duration of the excitatory effect indicating that temporal facilitation is of minor importance in generating this response. Temporal facilitation was found to play an important role in determining duration of the inhibitory response. Comparison of effects of unilateral and bilateral stimulation of the aortic C-fibres showed larger occlusion of durations of the excitatory than inhibitory responses.

Liver regeneration attenuates increased voluntary alcohol intake evoked by the liver damage.

Liver dysfunction induced in Wistar rats either surgically (by construction of portocaval anastomosis) or chemically (by chronic administration of thioacetamide) led to increased voluntary alcohol intake. Alcohol preference could be attenuated by liver regeneration that was triggered by a two-thirds hepatectomy done on cirrhotic rats. The brain serotonin system was activated in portocaval anastomosis rats and unchanged in thioacetamide-treated rats, thus suggesting that serotonin is not likely to be implicated in the mechanism(s) underlying development of alcohol preference in these rats. Also, tetrahydro-beta-carboline could possibly be excluded from consideration. Neither change in the brain concentration or distribution of tetrahydrobetacarboline after long-term treatment with thioacetamide could be found.

Pattern of ongoing discharge of single renal sympathetic neurons in the rabbit.

Ongoing discharge in single renal sympathetic neurons was first studied in vagotomized rabbits without baroreceptor information (60 min after section of the aortic nerves). Under urethane + chloralose anaesthesia interspike-interval histograms were compiled and discharge rates were measured in 79 neurons. The following parameters were analysed: (a) the shortest, (b) the preferred and (c) the longest interspike-intervals, (d) discharge rate, (e) spread of a histogram, (f) coefficient of symmetry, and (g) coefficient of variability. The type of distribution of histograms and 9 correlations between some parameters were also assessed. These parameters were considered to make up the pattern of the ongoing discharge. The shortest, preferred and longest interspike-intervals of the ongoing discharge were: 14.1 +/- 0.9, 30.4 +/- 3.5 and 1672 +/- 82 ms. The mean rate of discharge amounted to 1.78 +/- 0.08 spikes/s. Three out of 9 correlation coefficients between the above parameters were statistically significant. In a second part, the effect of section of the aortic nerves and of 4-aminopyridine (a drug known to enhance synaptic transmission) on the pattern of ongoing discharge were also studied. Ten minutes after section of the aortic nerves the rate of discharge significantly increased, the shortest interspike-interval diminished and coefficient of variability was not changed. The number of significant correlations rose from 3 to 9.4-Aminopyridine significantly increased the discharge rate, did not alter the shortest interspike-interval and increased the coefficient of variability. These data show that assessing several parameters of ongoing discharge making up its pattern may differentiate between the excitatory effects of section of the aortic nerves and administration of 4-aminopyridine and in this way help to elucidate the mechanisms of action of various factors affecting renal sympathetic discharge.

Inhibition of renal nerve discharge by liminal stimulation of non-myelinated aortic afferents.

The pattern of inhibitory responses of sympathetic nerve discharge to liminal activation of aortic C-fibres was studied in rabbits. The animals were anaesthetized with urethane and chloralose and vagotomized. Sympathetic postganglionic discharge was recorded from single fibres of the renal nerve. Inhibitory responses were elicited by single shocks or short trains (2-5 shocks at 10 Hz) and assessed from peri-stimulus time histograms. Clear-cut inhibition of the sympathetic discharge was observed in 6 out of 10 fibres. It was evoked by one shock in 5 fibres and by two shocks in 1 fibre. The mean latency of the inhibitory response elicited by one shock was 318 +/- 18 ms and its duration amounted to 196 +/- 22 ms (mean +/- SE). The increase in the number of shocks prolonged the duration of the inhibitory response without markedly affecting their latency.

Rapid immunoturbidimetric assay of albumin and immunoglobulin G in serum and cerebrospinal fluid with an automatic discrete analyser.

A method is presented to determine albumin and immunoglobulin G (IgG) in serum and cerebrospinal fluid (CSF) with an automatic discrete analyser. Concentrations of albumin and IgG in serum and CSF are compared with values obtained by radial immunodiffusion (RID). Ratios of albumin in CSF over albumin in serum and the so-called IgG index are calculated. Ratios obtained with the discrete analyser and with the RID are compared and discussed with respect to clinical diagnosis.