Dynamic Atomic Contributions To Infrared Intensities Of Fundamental Bands.

Dynamic atomic intensity contributions to fundamental infrared intensities are defined as the scalar products of dipole moment derivative vectors for atomic displacements and the total dipole derivative vector of the normal mode. Intensities of functional group vibrations of the fluorochloromethanes can be estimated within 6.5 km mol(-1) by displacing only the functional group atoms rather than all the atoms in the molecules. The asymmetric CF2 stretching intensity, calculated to be 126.5 km mol(-1) higher than the symmetric one, is accounted for by an 81.7 km mol(-1) difference owing to the carbon atom displacement and 40.6 km mol(-1) for both fluorine displacements. Within the Quantum Theory of Atoms in Molecules (QTAIM) model differences in atomic polarizations are found to be the most important for explaining the difference in these carbon dynamic intensity contributions. Carbon atom displacements almost completely account for the differences in the symmetric and asymmetric CCl2 stretching intensities of dichloromethane, 103.9 of the total calculated value of 105.2 km mol(-1). Contrary to that found for the CF2 vibrations intramolecular charge transfer provoked by the carbon atom displacement almost exclusively explains this difference. The very similar intensity values of the symmetric and asymmetric CH2 stretching intensities in CH2F2 arise from nearly equal carbon and hydrogen atom contributions for these vibrations. All atomic contributions to the intensities for these vibrations in CH2Cl2 are very small. Sums of dynamic contributions of the individual intensities for all vibrational modes of the molecule are shown to be equal to mass weighted atomic effective charges that can be determined from atomic polar tensors evaluated from experimental infrared intensities and frequencies. Dynamic contributions for individual intensities can also be determined solely from experimental data.1730378-3038

Reproducibility of an endurance test for master swimmers

This study aimed to verify the reproducibility of an endurance test for master swimmers. Methods: Seventeen male swimmers, aged from 30 to 50 years (35.06 ± 5.36), weight (78.71 ± 13.06 kg), height (174.35 ± 0.07 cm), participated in this study. The participants underwent the Progressive Swim Test (PSwT), which corresponds to swimming progressively to exhaustion in a 25-meter pool, guided by the recording of sound signals indicating the swimming rhythm. We verified the following variables: heart rate before the test (BHR) and right after the end of the test (AHR), followed by the rate of perceived exertion (RPE) and a total of laps performed (SN - swimming number). For comparison between the three days of tests, the one-way repeated measures ANOVA with Tukey's Post-Hoc was performed. Relative reproducibility was performed by the r test and the intraclass correlation coefficient (ICC). Absolute reproducibility was determined using the coefficient of variation (CV) and the confidence interval (CI). Results: The results showed high reproducibility in (PSwT) in master swimmers in the analyzed variables of intergroup and intragroup with relative reproducibility of r > 0.60 and ICC > 0.70 and absolute reproducibility with CI 95% (lower −1.10 and upper 0.99) and CV < 10%. Most of the cases were within the limits of agreement of the Bland-Altman tests, all variables were considered a level of significance with (p <0.05). Conclusion: The Progressive Swim Test (PSwT) is a reproducible instrument in the assessment of endurance in master swimmersThis study was supported by The Coordination for the Improvement of Higher Education Personnel (CAPES). The participants who enrolled in this study and the Laboratory for the Assessment of Aquatic Performance.info:eu-repo/semantics/publishedVersio

Growing in the Dark Warmth: The Case of Amazonian Fish Colossoma macropomum

Photoperiod is considered an important synchronizer of biological activities and endocrine pathways, including growth. As ectotherms, fish have many physiological functions controlled by the photoperiod. However, the combined effects of photoperiod and temperature should be clarified, particularly for tropical fish living near their upper thermal limit, as is the case of Amazonian fish. The central aim of this study was to evaluate the combined effect of photoperiod and temperature on growth and physiological aspects of tambaqui (Colossoma macropomum). Juveniles of tambaqui were distributed in 70 L tank, following a factorial design that included three photoperiods (light 0 h: darkness 24 h; light 12 h: darkness 12 h; and light 18 h: darkness 6 h) associated with three temperatures (26, 29, and 32°C). They were maintained under these conditions for 2 months. Fish reared in the dark at 29 and 32°C showed better performance compared to fish reared under extended light conditions at all temperatures. Among physiological responses, it has been observed that blood parameters tend to be disturbed with increasing temperature and that extended light conditions at low temperatures caused similar effects on the analyzed fish, suggesting blood hemoconcentration. Fish under extended light conditions showed an increase in glucose, cortisol, cholesterol, and total proteins, indicating additional physiological disturbances. In conclusion, our study shows that, unlike marine and temperate fish, C. macropomum, a fish species endemic to the Amazon, grows better in warmth dark, showing no significant physiological disturbances, similar to observations described for wild animals of this species. Our results support that changes in fish growth occur in response to environmental conditions. Therefore, fish species from freshwater, estuarine, and marine environments, must be specifically analyzed regarding the combination effects of photoperiod and temperature

Aqueous two-phase micellar systems in an oscillatory flow micro-reactor: Study of perspectives and experimental performance

Aqueous two-phase micellar systems (ATPMS) are micellar surfactant solutions with physical properties that make them very efficient for the extraction/concentration of biological products. In this work the main proposal that has been discussed is the possible applicability and importance of a novel oscillatory flow micro-reactor (micro-OFR) envisaged for parallel screening and/or development of industrial bioprocesses in ATPMS. Based on the technology of oscillatory flow mixing (OFM), this batch or continuous micro-reactor has been presented as a new small-scale alternative for biological or physical-chemical applications. RESULTS: ATPMS experiments were carried out in different OFM conditions (times, temperatures, oscillation frequencies and amplitudes) for the extraction of glucose-6-phosphate dehydrogenase (G6PD) in Triton X-114/buffer with Cibacron Blue as affinity ligand. CONCLUSION: The results suggest the potential use of OFR, considering this process a promising and new alternative for the purification or pre-concentration of bioproducts. Despite the applied homogenization and extraction conditions have presented no improvements in the partitioning selectivity of the target enzyme, when at rest temperature they have influenced the partitioning behavior in Triton X-114 ATPMS.The authors acknowledge the financial support from FCT (Fundacao para a Ciencia e Tecnologia/Portugal, SFRH/BPD/26108/2005), as well as from FAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo/Brasil), CNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico/Brasil), and CAPES (Coordenacao para Aperfeicoamento do Ensino Superior/Brasil)

Abundance of epigaeic arthropods in a Brazilian savanna under different fire frequencies

Fire is a major determinant of structure and dynamics in savannas, and the rapid increase of human activities in this biome has changed the natural burning regime. The effects of fire on the fauna of the cerrado (Brazilian savanna) are still poorly understood, and studies comparing sites frequently and infrequently burned are scarce. In this study, the abundance of epigaeic arthropod orders and trophic guilds was assessed in cerrado sites located in the Brazilian Central Plateau that were subjected to three burning frequencies: frequent (HighFi), intermediary (MidFi), and infrequent (LowFi). In general, we found a positive relationship between the abundance of epigaeic arthropods and fire frequency. When arthropods were analyzed by orders, the abundance of Collembola and Orthoptera was lower in the LowFi site, while for Hemiptera, it was higher in the MidFi site. No significant differences were found for Hymenoptera, Coleoptera, and Araneae. The abundance of detritivores and herbivores decreased from HighFi to LowFi, but did not change significantly for omnivores and predators. These results indicate that some arthropod groups may not only be resilient to fire effects, but actually might benefit from fire effects in the cerrado. Characterizing arthropod responses to burning frequency at high taxonomic or functional levels is important for applied studies. Based on the results of the current study, springtails and ants seem to be particularly appropriate focal groups for further exploratory studies on the effects of fire at the species level.71872

Interactions between hypoxia tolerance and food deprivation in Amazonian oscars, Astronotus ocellatus

Oscars are often subjected to a combination of low levels of oxygen and fasting during nest-guarding on Amazonian floodplains. We questioned whether this anorexia would aggravate the osmo-respiratory compromise. We compared fed and fasted oscars (1014 days) in both normoxia and hypoxia (1020 Torr, 4 h). Routine oxygen consumption rates (MO2) were increased by 75% in fasted fish, reflecting behavioural differences, whereas fasting improved hypoxia resistance and critical oxygen tensions (Pcrit) lowered from 54 Torr in fed fish to 34 Torr when fasting. In fed fish, hypoxia reduced liver lipid stores by approximately 50% and total liver energy content by 30%. Fasted fish had a 50% lower hepatosomatic index, resulting in lower total liver protein, glycogen and lipid energy stores under normoxia. Compared with hypoxic fed fish, hypoxic fasted fish only showed reduced liver protein levels and even gained glycogen (+50%) on a per gram basis. This confirms the hypothesis that hypoxia-tolerant fish protect their glycogen stores as much as possible as a safeguard for more prolonged hypoxic events. In general, fasted fish showed lower hydroxyacylCoA dehydrogenase activities compared with fed fish, although this effect was only significant in hypoxic fasted fish. Energy stores and activities of enzymes related to energy metabolism in muscle or gills were not affected. Branchial Na+ uptake rates were more than two times lower in fed fish, whereas Na+ efflux was similar. Fed and fasted fish quickly reduced Na+ uptake and efflux during hypoxia, with fasting fish responding more rapidly. Ammonia excretion and K+ efflux were reduced under hypoxia, indicating decreased transcellular permeability. Fasted fish had more mitochondria-rich cells (MRC), with larger crypts, indicating the increased importance of the branchial uptake route when feeding is limited. Gill MRC density and surface area were greatly reduced under hypoxia, possibly to reduce ion uptake and efflux rates. Density of mucous cells of normoxic fasted fish was approximately fourfold of that in fed fish. Overall, a 1014 day fasting period had no negative effects on hypoxia tolerance in oscars, as fasted fish were able to respond more quickly to lower oxygen levels, and reduced branchial permeability effectively. © 2013. Published by The Company of Biologists Ltd

Mamíferos Marinhos

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