Study on bisphenol-A polycarbonates samples crystallized by acetone vapor induction

Bisphenol-A polycarbonate (PC) is an important amorphous engineering polymer, which can have its crystallinity induced by special environmental conditions. Such crystallization can alter PC properties leading to flaws during its use or to new applications. Cast film samples of PC, prepared from chloroform solutions, were submitted to acetone vapor and characterized by polarized light microscopy (PLM), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). PLM showed that the PC crystalline structure was presented as spherulites of different sizes. DSC analysis exhibited a multiple melting behavior for the crystalline structure. FTIR has presented bands shifting and intensity decrease, compared to the samples before treatment. Compression molded samples were characterized by scanning electron microscopy (SEM), DSC and mechanical properties tests. For those samples, DSC also showed the presence of a crystalline phase, with a little increase on surface rugosity observed through SEM. Stress–strain tests presented a decrease on samples performance after acetone exposure.     

Preparation of MnO<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript>/AISI 304 Austenitic Stainless Steel Monoliths for Catalytic Combustion of Ethyl Acetate

Abstract  

The objective of this study is to explore the treatment conditions of austenitic stainless steel, AISI 304, for catalytic devices used in volatile organic compounds (VOCs) combustion. The variables studied were treatment exposure time, temperature and atmosphere. AISI 304 steel surface resulted in different morphologies depending on temperature and atmosphere. The oxide layer was composed of mixed oxides of Cr–Fe and Cr–Mn–Fe, forming octahedral and hexagonal crystals. The addition of manganese with the objective of reaching the ideal Mn/Fe ratio improved notably the catalytic performance.     

Heart and autonomic nervous system in connective tissue disorders

Heart rate variability (HRV) is a suitable diagnostic tool in identifying patients with autonomic nervous system (ANS) disorders even in pre-clinical stage. We have enrolled in this study all patients with large variety of connective tissue disorders, given the possibility of an involvement of ANS in these diseases. The study population consisted in eighty-five patients (68 females and 17 males), 35 of whom affected by systemic lupus erythematosus, 16 by rheumatoid arthritis, 14 by Sj?gren syndrome, 12 by progressive systemic sclerosis, 3 by Beh?et syndrome and 5 by antiphospholipid antibodies syndrome. The mean age ranged between 33.7 of patients with lupus erythematosus and 51.8 of those with Sj?gren syndrome. As control, we enrolled healthy subjects of different age, divided into two groups, to rule out the aging as potential source of considered parameters alteration. The autonomic function has been evaluated by 24 hours ambulatory monitoring, using a Zymed 1210 Scanner with Zymed 3.74-PC 1990 software. We have considered: in the time domain, the standard deviation of the RR intervals average (SDNN) and the percentage of RR adjacent intervals differing each other more than 50 msec (pNN50); in the frequency domain, the low (LF) and high (HF) frequencies, the LF/HF ratio, and the total power (RT). The HRV parameters resulted abnormal in every type of the connective tissue diseases considered: particularly SDNN, pNN50, LF, HF and RT (p < or = 0.01). In conclusion: the results of our study suggest that autonomic neuropathy may be present in any kind of connective tissue disorders even in preclinical stage.     

A comparative study of two isoforms of laccase secreted by the "white-rot" fungus Rigidoporus lignosus, exhibiting significant structural and functional differences

Two isoforms of laccase were obtained as the predominant phenol-oxidases in defined medium liquid cultures of the "white-rot" fungus Rigidoporus lignosus (R. lignosus). A characterization of the two laccases was made in terms of molecular mass, isoelectric point, metal content and N-terminal sequence. Furthermore, in order to gain information on the structural features related to the metal centers, a study of their geometric arrangement and their redox ability was made. It turned out that the two isoenzymes greatly differed with regard to pH stability, catalytic and copper centers features. It is proposed that all such differences are dependent on the amino acid sequences, which cause a distortion of the copper sites, thus accounting for the redox potential values and kinetic properties.     

Coexpression of CD69 and HLADR activation markers on synovial fluid T lymphocytes of patients affected by rheumatoid arthritis: a three-colour cytometric analysis

Haploid and diploid strains of Aspergillus nidulans have been repeatedly treated with the strong mutagen 6-N-hydroxylaminopurine (HAP) which causes only base substitutions. An enormous amount of variability may be rapidly accumulated in haploid or diploid strains of A. nidulans. In particular, in the diploids the analysis of the results shows that after 12 cycles of treatment the conidia differ from each other for about ten recessive lethals and therefore probably for several hundreds of mutations. The viability of the heterozygous multiply mutant diploids is not appreciably different from that of untreated controls. In the diploid strains the accumulated variability was very high. The treatment of a haploid strain during vegetative growth also caused a strong accumulation of mutations, even though deleterious, because they can be maintained in the heterokaryotic condition.     

Monitoring the effect of high pressure and transglutaminase treatment of milk on the evolution of flavour compounds during lactic acid fermentation using PTR-ToF-MS

In this study, the effects of thermal or high hydrostatic pressure (HHP) treatment of a milk base in the absence or presence of a transglutaminase (TGase) protein cross-linking step on the flavour development of yoghurt were investigated. The presence of several tentatively identified volatile flavour compounds (VOCs), both during the enzymatic treatment and the lactic acid fermentation of the milk base, were monitored using a proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS). The formation of the major flavour compounds (acetaldehyde, diacetyl, acetoin, and 2-butanone) followed a sigmoidal trend described by the modified Gompertz model. The HHP treatment of milk increased significantly the volatile compound formation rate whereas it did not affect the duration of the lag phase of formation, with the exception of acetaldehyde and diacetyl formation. On the contrary, the TGase cross-linking of milk did not significantly modify the formation rate of the volatile compounds but shortened the duration of the lag phase of their formation.     

Meiotic progression of isolated mouse spermatocytes under simulated microgravity

Progression through the prophase of the first meiotic division can be obtained in culture by treatment of mouse spermatocytes with the serine/threonine phosphatase inhibitor okadaic acid. Chromosome condensation during this G2/M transition involves the activation of the MAPK pathway, which causes the activation of Nek2 and the phosphorylation of the chromatin architectural protein Hmga2. In an effort to set up conditions to allow a spontaneous progression of mouse spermatocytes through meiosis, we have investigated the cell-cycle features of these cells cultured for 24 h with a rotary cell culture system in a humidified atmosphere in a thermostatic incubator to simulate a microgravity environment. Morphological analysis of nuclear squashes indicated a 2-fold increase in late-pachytene spermatocytes with highly condensed chromosomes, and a contemporaneous decrease of mid-pachytene cells with less condensed chromatin. Microgravity induced a 2-fold activation of the cyclinB-cdc2 complex, confirming at the molecular level that cell-cycle progression had occurred. Moreover, using immuno-kinase assays with specific substrates we have demonstrated that the meiotic progression obtained under microgravity conditions is accompanied by activation of the Erk1/p90Rsk2 pathway. These data indicated that activation of the MAPK pathway correlates with chromatin condensation even under conditions in which meiotic progression occurs spontaneously and is not induced by a drug. We suggest that culture under microgravity conditions might help to release the block that inhibits isolated spermatocytes from progressing through prophase at unit gravity, and to study the physiological events of germ cell differentiation in vitro.     

Embryonic diapause and its regulation

Embryonic diapause, a condition of temporary suspension of development of the mammalian embryo, occurs due to suppression of cell proliferation at the blastocyst stage. It is an evolutionary strategy to ensure the survival of neonates. Obligate diapause occurs in every gestation of some species, while facultative diapause ensues in others, associated with metabolic stress, usually lactation. The onset, maintenance and escape from diapause are regulated by cascades of environmental, hypophyseal, ovarian and uterine mechanisms that vary among species and between the obligate and facultative condition. In the best-known models, the rodents, the uterine environment maintains the embryo in diapause, while estrogens, in combination with growth factors, reinitiate development. Mitotic arrest in the mammalian embryo occurs at the G0 or G1 phase of the cell cycle, and may be due to expression of a specific cell cycle inhibitor. Regulation of proliferation in non- mammalian models of diapause provide clues to orthologous genes whose expression may regulate the reprise of proliferation in the mammalian context.