Chlorine-Functional Silsesquioxanes (POSS-Cl) as Effective Flame Retardants and Reinforcing Additives for Rigid Polyurethane Foams

The subject of the research was the production of silsesquioxane modified rigid polyurethane (PUR) foams (POSS-Cl) with chlorine functional groups (chlorobenzyl, chloropropyl, chlorobenzylethyl) characterized by reduced flammability. The foams were prepared in a one-step additive polymerization reaction of isocyanates with polyols, and the POSS modifier was added to the reaction system in an amount of 2 wt.% polyol. The influence of POSS was analyzed by performing a series of tests, such as determination of the kinetics of foam growth, determination of apparent density, and structure analysis. Compressive strength, three-point bending strength, hardness, and shape stability at reduced and elevated temperatures were tested, and the hydrophobicity of the surface was determined. The most important measurement was the determination of the thermal stability (TGA) and the flammability of the modified systems using a cone calorimeter. The obtained results, after comparing with the results for unmodified foam, showed a large influence of POSS modifiers on the functional properties, especially thermal and fire-retardant, of the obtained PUR-POSS-Cl systems.     

Random fluorene copolymers with on‐chain quinoxaline acceptor units

Two series of novel random polyfluorene copolymers containing quinoxaline units were prepared by stressing the coupling according to Yamamoto. The first series contains 2,3‐bis‐(4′‐tert‐butyl‐biphenyl‐4‐yl)benzo[g]quinoxaline and the second series 2,3‐bis‐(4′‐tert‐butyl‐biphenyl‐4‐yl)quinoxaline as energy accepting unit. The copolymers were identified by gel permeation chromatography, infrared spectroscopy, and nuclear magnetic resonance spectroscopy. Thermal properties were analyzed by thermal gravimetric analysis and differential scanning calorimetry revealing amorphous copolymers that are stable up to 430 °C. The morphology was investigated using atomic force microscopy. The optical properties in solutions and thin films were analyzed. Furthermore, the thin film electro‐optical properties were determined in monolayer polymer light‐emitting devices. Single layer devices were built with efficiencies ranging from 0.15 to 2.0 cd/A. For the random copolymers with 5 mol % benzo[g]quinoxazoline in the polyfluorene backbone some threefold efficiency enhancement from 1.1 to 3.0 cd/A was achieved by utilizing an ultra thin interlayer of poly(9,9‐di‐n‐octylfluorene‐2,7‐diyl)‐alt‐[1,4‐phenylene‐(4‐sec‐butylphenylimino)‐1,4‐phenylene] between PEDOT:PSS and the emissive random copolymer layer. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4773–4785, 2007     

Inactivation of Staphylococcus aureus and native microflora in human milk by high pressure processing

The storage of unpreserved food, including breast milk, is associated with the growth of microorganisms, including pathogenic bacteria. It is therefore necessary to use suitable processes to eliminate pathogenic microorganisms and reduce the total microbial count in order to ensure product safety for consumers. In the present study, samples of milk obtained from volunteers donating to the human milk bank were artificially contaminated with Staphylococcus aureus ATCC 6538. This bacteria was the model microorganism of choice, being relatively resistant to high pressure as well as posing the most serious risk to infant health. The results obtained show that high pressure processing can reduce the count of S. aureus by about 5?log units at 4°C and about 8?log units at 50°C, and totally eliminate Enterobacteriaceae after 5?min of treatment, and result in a total microbial count reduction after 10?min treatment at 500?MPa at 20°C and 50°C. This suggests the possibility of this technology being applied to ensure the adequate safety and quality of human breast milk in human milk banks.     

Simultaneous chiral separation and determination of carvedilol and 5′-hydroxyphenyl carvedilol enantiomers from human urine by high performance liquid chromatography coupled with fluorescent detection

A sensitive and specific high performance liquid chromatography coupled with fluorescent detection (HPLC-FL) and tandem mass spectrometry detection (HPLC-MS/MS) methods for separation and determination of carvedilol (CAR) enantiomers and 5′-hydroxyphenyl carvedilol (5′-HCAR) enantiomers has been developed and validated. The analysed compounds were extracted from human urine by solid phase extraction. Good enantioseparation of the studied enantiomers was achieved on CHIRALCEL® OD-RH column using 0.05% trifluoroacetic acid and 0.05% diethylamine in water and acetonitrile in a gradient elution. The mass spectrometric data were acquired using the multiple reaction monitoring mode by positive electrospray ionisation. The method was validated over the concentration range from 25.0 ng mL^?1 to 200 ng mL^?1 for the analysed compounds. The limit of quantification varied from 14.2 ng mL^?1 to 24.2 ng mL^?1. Both the repeatability and inter-day precisions were below 10.0%, and the accuracy varied from ?13.2% to 3.77%. The extraction recoveries ranged from 79.2% to 108%. The present paper reports the method for the simultaneous determination of CAR enantiomers and their metabolite enantiomers (5′-HCAR) in human urine samples. This newly developed method was successfully used to analyse the aforementioned analytes in human urine samples obtained from patients suffering from cardiovascular disease.      

Activity and Diversity of Microorganisms in Root Zone of Plant Species Spontaneously Inhabiting Smelter Waste Piles

The aim was to assess plant driven changes in the activity and diversity of microorganisms in the top layer of the zinc and lead smelter waste piles. The study sites comprised two types (flotation waste—FW and slag waste—SW) of smelter waste deposits in Piekary Slaskie, Poland. Cadmium, zinc, lead, and arsenic contents in these technosols were extremely high. The root zone of 8 spontaneous plant species (FW—Thymus serpyllum, Silene vulgaris, Solidago virgaurea, Echium vulgare, and Rumex acetosa; and SW—Verbascum thapsus; Solidago gigantea, Eupatorium cannabinum) and barren areas of each waste deposit were sampled. We observed a significant difference in microbial characteristics attributed to different plant species. The enzymatic activity was mostly driven by plant-microbial interactions and it was significantly greater in soil affected by plants than in bulk soil. Furthermore, as it was revealed by BIOLOG Ecoplate analysis, microorganisms inhabiting barren areas of the waste piles rely on significantly different sources of carbon than those found in the zone affected by spontaneous plants. Among phyla, Actinobacteriota were the most abundant, contributing to at least 25% of the total abundance. Bacteria belonging to Blastococcus genera were the most abundant with the substantial contribution of Nocardioides and Pseudonocardia, especially in the root zone. The contribution of unclassified bacteria was high—up to 38% of the total abundance. This demonstrates the unique character of bacterial communities in the smelter waste.     

Rapid-Scan Electron Paramagnetic Resonance of Highly Resolved Hyperfine Lines in Organic Radicals.

X-band (ca. 9 GHz) fluid solution rapid-scan electron paramagnetic resonance spectra are reported for radicals with multiline spectra and resolution of hyperfine lines as narrow as 30 mG. Highly-resolved spectra of 3-carbamoyl-2,2,5,5-tetramethylpyrrolidin-1-yloxy, diphenylnitroxide, galvinoxyl, and perylene cation radical with excellent signal-to-noise are shown, demonstrating the capabilities of the rapid-scan technique to characterize very small, well-resolved hyperfine couplings. To acquire high resolution spectra the signal bandwidth must be less than the resonator bandwidth. Signal bandwidth is inversely proportional to linewidth and proportional to scan rate. Resonator bandwidth is inversely proportional to resonator Q. Proper selection of scan rate and resonator Q is needed to achieve resolution of closely-spaced narrow EPR lines.     

Cosmogenic 22Na, 7Be and terrestrial 137Cs, 40K radionuclides in ground level air samples collected weekly in Kraków (Poland) over years 2003–2006

A low background gamma spectrometer with an Etruscan, 2500 years old lead shield and a muon veto detector were applied to study ²²Na and ⁷Be activity concentration in ground level air aerosol samples collected weekly over the years 2003–2006 in Kraków. Each sample was formed with ca 100 000 m³ of passed air, collected with two parallel ASS-500 high volume air samplers. The results for ⁴⁰K and ¹³⁷Cs are also presented for reference and comparison. Presented frequency distributions for activity concentration and correlation between the obtained results are discussed. The activity concentration results confirmed seasonal variation of activity to be different for all the investigated radionuclides. Moreover, the seasonal variation in nucleus activity ratio was also noticed for ²²Na and ⁷Be. Cosmogenic radionuclides being mainly of stratospheric origin, are subsequently attached to fine aerosols, via which they are transported to the ground level air. The mean aerosol transport time within the troposphere was estimated as equal to 7.5 days on average, reaching even 50 days in warm seasons. Limitations of the applied model were identified.     

Enzymatic synthesis of tryptamine and its halogen derivatives selectively labeled with hydrogen isotopes

Nine isotopomers of tryptamine and its halogen derivatives, labeled with deuterium, tritium in side chain, i.e., [(1R)-²H]-, [(1R)-³H]-, 5-F-[(1R)-²H]-, 5-F-[(1R)-³H]-, 5-Br-[(1R)-²H]-, double labeled [(1R)-²H/³H]-, 5-F-[(1R)-²H/³H]-, and ring labeled [4-²H]-, and [5-²H]-tryptamine, were obtained by enzymatic decarboxylation of l-Trp and its appropriate derivatives in deuteriated or tritiated media, respectively. Intermediates: [5′-²H]-l-Trp used for further decarboxylation was synthesized by enzymatic coupling of [5-²H]-indole with S-methyl-l-cysteine, and [4′-²H]-l-Trp was obtained by isotope exchange ¹H/²H of the authentic l-Trp dissolved in heavy water induced by UV-irradiation. Doubly labeled [(1R)-²H/³H]- and 5-F-[(1R)-²H/³H]-tryptamine were obtain by decarboxylation of l-Trp or [5′-F]-l-Trp carried out in ²H³HO incubation medium.     

A microfluidic system to study the cytotoxic effect of drugs: the combined effect of celecoxib and 5-fluorouracil on normal and cancer cells

We have investigated the response of normal and cancer cells to exposure a combination of celecoxib (Celbx) and 5-fluorouracil (5-FU) using a lab-on-a-chip microfluidic device. Specifically, we have tested the cytotoxic effect of Celbx on normal mouse embryo cells (Balb/c 3T3) and human lung carcinoma cells (A549). The single drugs or their combinations were adjusted to five different concentrations using a concentration gradient generator (CGG) in a single step. The results suggest that Celbx can enhanced the anticancer activity of 5-FU by stronger inhibition of cancer cell growth. We also show that the A549 cancer cells are more sensitive to Celbx than the Balb/c 3T3 normal cells. The results obtained with the microfluidic system were compared to those obtained with a macroscale in vitro cell culture method. In our opinion, the microfluidic system represents a unique approach for an evaluation of cellular response to multidrug exposure that also is more simple than respective microwell plate assays.

Polypyrrole–gold nanostructured composite,active and durable electrocatalytic material

The consequences of treatment of gold nanocrystals present in polypyrrole–gold composites and electrodeposited gold nanocrystals (PPY–Au and Au NPs) with OH radicals generated in Fenton’s reaction were investigated. Particularly, the changes in the morphology and the electrochemical properties of those materials are shown. For both materials, the etching effect was noticed. Contrary to significantly reduced catalytic activity, the changes observed in size and shape of gold nanostructures were less pronounced. In the case of PPY–Au composite material, the etching effects were less intense. Even after a 60-min radical treatment of the PPY–Au composite material, the gold–nanocrystal catalytic activity remained high. The limited dissolution of the gold nanocrystals in the PPY–Au composites, compared to bare Au NPs, can be explained by the presence of the polymer which served as a kind of protective barrier against the oxidizing agent. A decrease in the electrocatalytic properties vs. the electrooxidation of ethanol of both forms of gold nanocrystals were observed after the treatment with hydroxyl radicals.