Environmentally Friendly Radiation Hard d-Limonene and Laccol Copolymers Synthesized via Cationic Copolymerization

In the modern world, petroleum-based synthetic polymers have a great number of applications in fields ranging from food packaging to space travel. However, the processing of petroleum products and the resulting depletion of fossil fuels are major environmental concerns in today's society. As a result, the development of sustainable polymers which are made up of renewable resources and waste products is an immerging area of research. Considering the world food production, citrus fruit is most abundant and its contribution to waste generation is immense. Therefore, this study focuses on offering an alternative to the use of petroleum-based polymers and also providing a regulatory pathway to manage citrus waste by developing novel copolymers of laccol and limonene. Two environmentally friendly compounds, laccol, derived from the sap of Toxicodendron succedaneum tree and limonene, extracted from orange peels, were copolymerized via cationic polymerization to generate d-limonene:laccol copolymers with radiation hardening capabilities which is relevant in fields such as nuclear energy generation, medicinal sterilization, commercial irradiation, and space exploration. Formation of these copolymers was verified with infrared and nuclear magnetic resonance analysis. The synthesized copolymers were characterized using different methods and exposed to Co-60 gamma radiation to identify alterations to their properties. POLYM. ENG. SCI., 60:607–618, 2020. © 2019 Society of Plastics Engineers     

Synthesis and thermal stability of carborane-containing phosphazenes

Carborane-substituted polyphosphazenes were prepared by the thermal polymerization of phenyl-carboranyl pentachlorocyclotriphosphazene. Successive isothermal vacuum pyrolyses were conducted on the polymer and examined for structural changes by infrared spectroscopy. The degradation products were ascertained by gas chromatography-mass spectrometric analysis. It was found that the presence of the carborane group improves the thermal stability of the polymer by retarding the ring-chain equilibrium processes of decomposition.     

Caspase-mediated cleavage of DNA topoisomerase I at unconventional sites during apoptosis

Previous studies have demonstrated that topoisomerase I is cleaved late during apoptosis, but have not identified the proteases responsible or examined the functional consequences of this cleavage. Here, we have shown that treatment of purified topoisomerase I with caspase-3 resulted in cleavage at DDVD146 downward arrowY and EEED170 downward arrowG, whereas treatment with caspase-6 resulted in cleavage at PEDD123 downward arrowG and EEED170 downward arrowG. After treatment of Jurkat T lymphocytic leukemia cells with anti-Fas antibody or A549 lung cancer cells with topotecan, etoposide, or paclitaxel, the topoisomerase I fragment comigrated with the product that resulted from caspase-3 cleavage at DDVD146 downward arrowY. In contrast, two discrete topoisomerase I fragments that appeared to result from cleavage at DDVD146 downward arrowY and EEED170 downward arrowG were observed after treatment of MDA-MB-468 breast cancer cells with paclitaxel. Topoisomerase I cleavage did not occur in apoptotic MCF-7 cells, which lack caspase-3. Cell fractionation and band depletion studies with the topoisomerase I poison topotecan revealed that the topoisomerase I fragment remains in proximity to the chromatin and retains the ability to bind to and cleave DNA. These observations indicate that topoisomerase I is a substrate of caspase-3 and possibly caspase-6, but is cleaved at sequences that differ from those ordinarily preferred by these enzymes, thereby providing a potential explanation why topoisomerase I cleavage lags behind that of classical caspase substrates such as poly(ADP-ribose) polymerase and lamin B1.     

Iron-ruthenium catalyst for the water-gas shift reaction

Iron-ruthenium catalysts prepared by impregnation of calcination products of -, , -and -iron oxide-hydroxides with either ruthenium chloride or ruthenium red were tested for the activity for the water-gas shift reaction. The effect of support, ruthenium containing impregnation agent and thermal treatment on catalyst performance was discussed.     

Pneumatization of the middle nasal turbinate: a CT study

Anatomic variations of the middle turbinate may be an important factor in the pathogenesis of inflammatory processes of the paranasal sinuses. A detailed analysis of coronal and axial plane CT scans of the paranasal sinuses obtained from 120 patients was performed. Paradoxical curve of the middle concha was detected in 24.2% of patients. Pneumatized middle turbinate was found in 42.5% and "true" concha bullosa in 8.3% of patients. Bilateral concha bullosa was found in 1.7% of patients.     

The most important bioactive components of cold pressed oil from different pumpkin (Cucurbita pepo L.) seeds

The composition and content of certain bioactive components of the cold pressed oil obtained from six samples of pumpkin seeds (Cucurbita pepo L.) cultivated in Serbia were analyzed by GC and GC/MS. The composition and content of fatty acids, tocopherols and phytosterols, and the total content of squalene were determined. The results indicate oil's excellent quality, with high contents of monounsaturated fatty acids (37.1 ± 0.70–43.6 ± 0.69 g/100 g of total fatty acids), total tocopherols (38.03 ± 0.25–64.11 ± 0.07 mg/100 g of oil), sterols (718.1 ± 6.1–897.8 ± 6.8 mg/100 g of oil) and especially squalene (583.2 ± 23.6–747 ± 16 mg/100 g of oil). High content of squalene, phytosterols and monounsaturated fatty acids recommend the use of this type of the oil in the nutritional and medical purposes.     

Harmonization of individual dosimetry quality control within metrology system of a small country

A programme of harmonization of individual dosimetry quality control organized in the framework of a distributed metrology system is presented as seen from the experiences gained in Slovenia. As a part of the programme intercomparison of dosimetry services was organized and basic characteristics of dosimetry systems compared. Results are discussed with suggestions for further improvements of quality assurance.     

Synthesis and characterization of novel laccol based polyurethanes

Development of polyurethanes (PU) has come a long way from their origin in 1937 and has unique applications in a diverse set of fields. Recent PU developments are focusing more on the naturally-derived diols in the synthesis process in an effort to make them more environmentally friendly. In this study, three different diisocyanates (aliphatic, cycloaliphatic, and aromatic diisocyanates) were combined with laccol, which extracted from Vietnamese lacquer sap (Toxicodendron succedanea) to synthesize novel PUs. Influence of the different diisocyanates in novel PUs, hydrogen bonding capability, and crosslinking ability were investigated to provide a broader characteristic scope for future developments. Resulting materials illustrated good thermal stability after exposed to higher temperatures and the hydrogen bonding regions corresponding to N H (3326 cm⁻¹) and CO (1652 cm⁻¹) groups were shifted to higher wavenumber according to Fourier transform infra-red spectroscopy analysis. Further curing occurred with temperature treatment and improved the overall quality of novel PUs. Powder X-ray analysis, micro hardness, and swelling analysis were utilized to identify molecular packing and crosslinking effects. Higher crosslink density observed for cycloaliphatic and aromatic diisocyanate incorporated novel polyurethanes compared to aliphatic diisocyanate incorporated polyurethane.