Expanded Polystyrene Foam Formed from Polystyrene Beads Coated with a Nanocrystalline SiO2 Film and the Analysis of Its Moisture Adsorption and Resistance to Mechanical Stress

Conventional expanded polystyrene can absorb moisture, which significantly degrades its properties. In the present study, it was demonstrated that SiO₂ can be deposited on polystyrene beads before pre-expansion and molding steps. Under the applied test conditions, expanded polystyrene with nanocrystalline SiO₂ additives had approximately 10% lower moisture adsorption and an 8.4% better resistance to deformation. Expanded polystyrene analysis suggested that the observed improvements were caused by the hydrophobic nature of nanocrystalline SiO₂ and, even more importantly, because SiO₂ acted as an amalgamation catalyst and significantly increased adhesion between the expanded polystyrene beads during the expanded polystyrene molding process.     

Early and late results of surgical treatment in patients with primary mediastinal germ cell tumors]

A group of 37 patients--20 (54%) men and 17 (46%) women--aged 2-65, mean 31.6 years, was treated between 1978 and 1995 for different kinds of primary mediastinal germ cell tumours. In 14 (37.8%) of them a mature solid teratoma was diagnosed, in 13 (35.1%)--dermoid cyst, in 5 (13.5%)--malignant teratoma, in 1 (2.7%)--immature teratoma, in 4 (10.8%)--seminoma. Mediastinal tumour was removed completely in 30 (81.1%) patients, partially in 7 (18.9%). Out of 37 patients, 3 (8.1%) died during postoperative time. Out of 26 patients discharged after surgical removal of mature teratomas, all are alive and have been followed-up for 10 years (17 patients) or 5 years (6 patients). Out of 8 discharged after surgical removal of malignant neoplasm, 3 are alive and all of them had primary mediastinal seminoma. One of them has survived 17 years after complete resection, and two patients--7.5 years and 2 years after partial resection and radiotherapy. Mean survival time is 4 years and 2 months for all patients with malignant neoplasm.     

Mechanical characteristics of optical coatings prepared by various techniques: a comparative study

Good performance of optical coatings depends on the appropriate combination of optical and mechanical properties. Therefore, successful applications require good understanding of the relationship between optical microstructural and mechanical characteristics and film stability. In addition, there is a lack of standard mechanical tests that allow one to compare film properties measured in different laboratories. We give an overview of the methodology of mechanical measurements suitable for optical coatings; this includes depth-sensing indentation, scratch resistance, friction, abrasion and wear testing, and stress and adhesion evaluation. We used the techniques mentioned above in the same laboratory to systematically compare the mechanical behavior of frequently used high- and low-index materials, namely, TiO2, Ta2O5, and SiO2, prepared by different complementary techniques. They include ion-beam-assisted deposition by electron-beam evaporation, magnetron sputtering, dual-ion-beam sputtering, plasma-enhanced chemical-vapor deposition, and filtered cathodic arc deposition. The mechanical properties are correlated with the film microstructure that is inherently related to energetic conditions during film growth.     

Single-material inhomogeneous optical filters based on microstructural gradients in plasma-deposited silicon nitride

Transparent hydrogenated amorphous silicon nitride (SiNx:H) coatings were prepared by dual-mode microwave-radio-frequency plasma-enhanced chemical vapor deposition. By controlling the effects of plasma density and ion energy on the film growth, it was possible to modify the microstructure of the coatings and hence the refractive index n. Using this method, we were able to vary n from 1.6 to 2.0, at 550 nm, by adjusting the power levels of the radio-frequency and microwave components while keeping the gas composition (SiH4, N2) and pressure constant. An inhomogeneous bandpass filter with a controlled refractive-index depth profile was fabricated, and its optical performance was compared with that of its multilayer counterpart. Besides the attractive optical features of such single-material rugate filters, we found that the mechanical resistance of inhomogeneous films is superior to that of multilayer systems.     

Anti‐corrosion additive for concrete

The Building Research Institute in Warsaw has developed an organic concrete additive, known as Dikszopt, which is derived from tanning oak extract. Tests, mostly in the laboratory but some in application trials, show that it has a remarkable ability to protect reinforcing steel against corrosion, notably in carbonized concrete. It also appears to improve the consistency of the concrete mix and retard the setting time, as discussed in this article from the Institute.     

Calcium Ions Regulate K+ Uptake into Brain Mitochondria: The Evidence for a Novel Potassium Channel

The mitochondrial response to changes of cytosolic calcium concentration has a strong impact on neuronal cell metabolism and viability. We observed that Ca²⁺ additions to isolated rat brain mitochondria induced in potassium ion containing media a mitochondrial membrane potential depolarization and an accompanying increase of mitochondrial respiration. These Ca²⁺ effects can be blocked by iberiotoxin and charybdotoxin, well known inhibitors of large conductance potassium channel (BK_Ca channel). Furthermore, NS1619 – a BK_Ca channel opener – induced potassium ion–specific effects on brain mitochondria similar to those induced by Ca²⁺. These findings suggest the presence of a calcium-activated, large conductance potassium channel (sensitive to charybdotoxin and NS1619), which was confirmed by reconstitution of the mitochondrial inner membrane into planar lipid bilayers. The conductance of the reconstituted channel was 265 pS under gradient (50/450 mM KCl) conditions. Its reversal potential was equal to 50 mV, which proved that the examined channel was cation-selective. We also observed immunoreactivity of anti-β₄ subunit (of the BK_Ca channel) antibodies with ~26 kDa proteins of rat brain mitochondria. Immunohistochemical analysis confirmed the predominant occurrence of β₄ subunit in neuronal mitochondria. We hypothesize that the mitochondrial BK_Ca channel represents a calcium sensor, which can contribute to neuronal signal transduction and survival.     

Interfacial activity of narrow-range alcohol oxyethylates

Surface and interfacial tension isotherms for narrow-range distribution ALFOL 1214 alcohol oxyethylates were determined and compared with those obtained for broad-range alcohol oxyethylates. Various adsorption parameters were estimated. The effectiveness of surface tension reduction decreases when the length of polyoxyethylene hydrophile increases. Micellization is observed at log cmc ranging from −4.7 to −3.3. Effects of the length and distribution of the polyoxyethylene chain on cmc are very small. A minimum of A _min/N _av ^0.5 is obtained for N _av=8, where A _min and N _av denote the minimum interfacial area occupied by a statistical molecule at the saturated interface and the average degree of oxyethylation, respectively. The interface becomes saturated at pC ₂₀=−5.61±0.35, where pC ₂₀ denotes the logarithm of concentration required to obtain the surface pressure equal to 20 mNm⁻¹. The highest and lowest values of the surface excess at saturation and the free energy of adsorption, respectively, are obtained for an average degree of oxyethylation equal to 8. Parameters are correlated with the average degree of oxyethylation and the oxyethylene chain distribution parameter according to empirical second-order polynomials. Small differences in adsorption abilities at the water/air interface are only observed for narrow- and broad-range distributed oxyethylates. The differences become important for adsorption at the hexadecane/water interface. The lowest values of interfacial tension are obtained for narrow-range oxyethylates with N _av=7 and 8. The Krefeld fabric detergency tests indicated that the best detergency was observed for alcohol oxyethylates with N _av=5–7. Narrow-range oxyethylates exhibit somewhat better washing abilities than the broad-range products. No relationship between detergency of alcohol oxyethylates and their abilities to adsorb at the water/air and water/hydrocarbon interfaces is observed.     

A search for optimal acrylic carriers for immobilization of penicillin acylase

Acrylic carriers were obtained by aminolysis of nitrile or ester groups in copolymers or terpolymers synthesized from acrylonitrile, acrylic esters and divinylbenzene or ethylene dimethacrylate in the presence of a mixture of inert diluents. The influence of the supermolecular structure of these carriers, generated during the suspension polymerization by adding a mixture of inert diluents, on the carrier properties was observed. Acrylic carriers for immobilization of penicillin acylase should be obtained from either porous or ‘sol’-type copolymers which aquire after aminolysis the structure of expanded gel.     

Evaluation of functional properties of offal proteins

Evaluation of functional properties of beef heart and lip tissue proteins was based on the data obtained in the following determinations: protein extractability, fat emulsifying capacity, emulsion stability, gel forming ability, and water holding capacity after heat treatment. Beef skeletal muscles were used as the control. It was found that extractability of proteins of the raw materials was low as well as their ability to stabilize emulsions was on a low level. Proteins soluble at high ionic strength (fraction HIS) of beef heart and lip tissue emulsified 80.7 ml and 68.9 ml of oil/100 mg of protein, respectively, as compared to 106.6 ml in the control group. Analogically, protein soluble at low ionic strength (fraction LIS) emulsified 77.9 ml, 61.2 ml and 100.4 ml of oil, respectively. Emulsion stability of offal proteins appeared to be dependent on ionic strength. Generally at higher concentrations of salt their ability to stabilize emulsions was better as well as their water holding capacity increased. Their gelation properties as compared to control were also low. In each case, the functionality of cardiac proteins proved to be better than that of beef lip tissue.     

Low-temperature atomic layer deposition of Al2O3 thin coatings for corrosion protection of steel: Surface and electrochemical analysis

ToF-SIMS, XPS, voltammetry and EIS investigation of the anti-corrosion properties of thin (10, 50 and 100 nm) alumina coatings grown by atomic layer deposition at 160 °C on steel is reported. Surface analysis shows a thickness-independent Al₂O₃ stoichiometry of the coating and trace contamination by the growth precursors. The buried coating/alloy interface has iron oxide formed in ambient air and/or resulting from the growth of spurious traces in the initial stages of deposition. Electrochemical analysis yields an exponential decay of the coating porosity over four orders of magnitude with increasing thickness, achieved by sealing of the more defective first deposited 10 nm.