Weighted mean depth of zooplankton measured during various cruises to the Baltic Sea

The Baltic Sea is the largest brackish water area of the world. On the basis of the data from 16 cruises, we show the seasonal and vertical distribution patterns of the appendicularians Fritillaria borealis, Oikopleura dioica and the cyclopoid copepod Oithona similis, in the highly stratified Bornholm Basin. These species live at least temporarily below the permanent halocline and use different life strategies to cope with the brackish environment. The cold-water species F. borealis is abundant in the upper layers of the water column before the thermocline develops. With the formation of the thermocline abundance decreases and the specimens outlast higher temperatures below the halocline. Distribution and strategy suggest that F. borealis might be a glacial relict species in the Baltic Sea. Although Oikopleura dioica is only abundant during summer, O. similis is present all year round. Both species have in common that their vertical distribution is restricted to the waters below the halocline, most likely due to their requirements of higher salinities. We argue that the observed strategies are determined by ecophysiological constraints and life history traits. These species share an omnivorous feeding behaviour and the capability to utilise a spectra of small particles as food. As phytoplankton concentration is negligible below the halocline, we suggest that these species feed on organic material and heterotrophic organisms that accumulate in the density gradient of the halocline. Therefore, the deep haline waters in the Baltic Sea represent a habitat providing shelter from predation and food supply for adapted species that allows them to gather sufficient resources and to maintain populations.

Rare earth element concentrations and geochemistry of carbonate minerals from the Logatchev Hydrothermal Field and the Gakkel Ridge

The ultramafic-hosted Logatchev Hydrothermal Field (LHF) at 15°N on the Mid-Atlantic Ridge and the Arctic Gakkel Ridge (GR) feature carbonate precipitates (aragonite, calcite, and dolomite) in voids and fractures within different types of host rocks. We present chemical and Sr isotopic compositions of these different carbonates to examine the conditions that led to their formation. Our data reveal that different processes have led to the precipitation of carbonates in the various settings. Seawater-like 87Sr/86Sr ratios for aragonite in serpentinites (0.70909 to 0.70917) from the LHF are similar to those of aragonite from the GR (0.70912 to 0.70917) and indicate aragonite precipitation from seawater at ambient conditions at both sites. Aragonite veins in sulfide breccias from LHF also have seawater-like Sr isotope compositions (0.70909 to 0.70915), however, their rare earth element (REE) patterns show a clear positive europium (Eu) anomaly indicative of a small (< 1%) hydrothermal contribution. In contrast to aragonite, dolomite from the LHF has precipitated at much higher temperatures (~100 °C), and yet its 87Sr/86Sr ratios (0.70896 to 0.70907) are only slightly lower than those of aragonite. Even higher temperatures are calculated for the precipitation of deformed calcite veins in serpentine-talc fault schists form north of the LHF. These calcites show unradiogenic 87Sr/86Sr ratios (0.70460 to 0.70499) indicative of precipitation from evolved hydrothermal fluids. A simple mixing model based on Sr mass balance and enthalpy conservation indicates strongly variable conditions of fluid mixing and heat transfers involved in carbonate formation. Dolomite precipitated from a mixture of 97% seawater and 3% hydrothermal fluid that should have had a temperature of approximately 14 °C assuming that no heat was transferred. The much higher apparent precipitation temperatures based on oxygen isotopes (~ 100 °C) may be indicative of conductive heating, probably of seawater prior to mixing. The hydrothermal calcite in the fault schist has precipitated from a mixture of 67% hydrothermal fluid and 33% seawater, which should have had an isenthalpic mixing temperature of ~ 250 °C. The significantly lower temperatures calculated from oxygen isotopes are likely due to conductive cooling of hydrothermal fluid discharging along faults. Rare earth element patterns corroborate the results of the mixing model, since the hydrothermal calcite, which formed from waters with the greatest hydrothermal contribution, has REE patterns that closely resemble those of vent fluids from the LHF. Our results demonstrate, for the first time, that (1) precipitation from pure seawater, (2) conductive heating of seawater, and (3) conductive cooling of hydrothermal fluids in the sub-seafloor all can lead to carbonate precipitation within a single ultramafic-hosted hydrothermal system.

Geochemistry of lower sheeted dike complex samples of ODP Holes 137-504B and 140-504B

Rocks of the lower sheeted dike complex of Hole 504B sampled during Leg 140 were analyzed for major and trace element compositions to investigate the effects of igneous processes and hydrothermal alteration on the compositions of the rocks. The rocks are relatively uniform in composition and similar to the shallower dikes. They are moderately evolved mid-ocean-ridge basalts (MORB) with relatively high MgO (7.9-10 wt%) and Mg# (0.60-0.70), and have unusually low incompatible element contents (TiO2 = 0.42-1.1 wt%, Zr = 23-62 ppm). Discrete compositional intervals in the hole reflect varying degrees of differentiation, and olivine and plagioclase accumulation in the rocks, and may be related to injection of packets of dikes having similar compositions. Systematic depletions of total REE, Zr, Y, TiO2, and P2O5 in centimeter-size patches are most likely attributed to exclusion of highly differentiated, late-stage interstitial liquids from small portions of the rocks. The rocks exhibit increased H2O+ reflecting hydrothermal alteration. Replacement of primary plagioclase by albite and oligoclase led to local gains of Na2O, losses of CaO, and slightly positive Eu anomalies. Some mobility of P2O5 led to minor increases and decreases in P2O5 contents, and some local mobility of Ti may have occurred during alteration of titanomagnetite to titanite. Higher temperatures of alteration in the lower sheeted dikes led to breakdown of pyroxene and sulfide minerals and losses of Zn, Cu, and S to hydrothermal fluids. Later addition of anhydrite to the rocks in microfractures and replacing plagioclase caused local increases in sulfur contents. The lower sheeted dikes are a major source of metals to hydrothermal fluids for the formation of metal sulfide deposits on and within the seafloor.

Intact and core tetraether lipids in water column profiles of suspended particulate matter and of surface sediment samples off Cape Blanc, NW Africa

In the reconstruction of sea surface temperature (SST) from sedimentary archives, secondary sources, lateral transport and selective preservation are considered to be mainly negligible in terms of influencing the primary signal. This is also true for the archaeal glycerol dialkyl glycerol tetraethers (GDGTs) that form the basis for the TEX86 SST proxy. Our samples represent four years variability on a transect off Cape Blanc (NW Africa). We studied the subsurface production, vertical and lateral transport of intact polar lipids and core GDGTs in the water column at high vertical resolution on the basis of suspended particulate matter (SPM) samples from the photic zone, the subsurface oxygen minimum zone (OMZ), nepheloid layers (NL) and the water column between these. Furthermore we compared the water column SPM GDGT composition with that in underlying surface sediments. This is the first study that reports TEX86 values from the precursor intact polar lipids (IPLs) associated with specific head groups (IPL -specific TEX86). We show a clear deviation from the sea surface GDGT composition in the OMZ between 300 and 600 m. Since neither lateral transport nor selective degradation provides a satisfactory explanation for the observed TEX-derived temperature profiles with a bias towards higher temperatures for both core- and IPL -specific TEX86 values, we suggest that subsurface in situ production of archaea with a distinct relationship between lipid biosynthesis and temperature is the responsible mechanism. However, in the NW-African upwelling system the GDGT contribution of the OMZ to the surface sediments does not seem to affect the sedimentary TEX86 as it shows no bias and still reflects the signal of the surface waters between 0 and 60 m.

Experimental data on photophysiology and growth rates of the invasive foraminifera Amphistegina lobifera showing high thermal tolerance from the Eastern Mediterranean and the Gulf of Aqaba

Invasive species allow an investigation of trait retention and adaptations after exposure to new habitats. Recent work on corals from the Gulf of Aqaba (GoA) shows that tolerance to high temperature persists thousands of years after invasion, without any apparent adaptive advantage. Here we test whether thermal tolerance retention also occurs in another symbiont-bearing calcifying organism. To this end, we investigate the thermal tolerance of the benthic foraminifera Amphistegina lobifera from the GoA (29° 30.14167 N 34° 55.085 E) and compare it to a recent "Lessepsian invader population" from the Eastern Mediterranean (EaM) (32° 37.386 N, 34°55.169 E). We first established that the studied populations are genetically homogenous but distinct from a population in Australia, and that they contain a similar consortium of diatom symbionts, confirming their recent common descent. Thereafter, we exposed specimens from GoA and EaM to elevated temperatures for three weeks and monitored survivorship, growth rates and photophysiology. Both populations exhibited a similar pattern of temperature tolerance. A consistent reduction of photosynthetic dark yields was observed at 34°C and reduced growth was observed at 32°C. The apparent tolerance to sustained exposure to high temperature cannot have a direct adaptive importance, as peak summer temperatures in both locations remain <32°C. Instead, it seems that in the studied foraminifera tolerance to high temperature is a conservative trait and the EaM population retained this trait since its recent invasion. Such pre-adaptation to higher temperatures confers A. lobifera a clear adaptive advantage in shallow and episodically high temperature environments in the Mediterranean under further warming.

Mortality and climatic/environmental correlates of Widdringtonia cedargensis trees in the Cederberg, South Africa

Background: Conifer populations appear disproportionately threatened by global change. Most examples are, however, drawn from the northern hemisphere and long-term rates of population decline are not well documented as historical data are often lacking. We use a large and long-term (1931-2013) repeat photography dataset together with environmental data and fire records to account for the decline of the critically endangered Widdringtonia cedarbergensis. Eighty-seven historical and repeat photo-pairs were analysed to establish 20th century changes in W. cedarbergensis demography. A generalized linear mixed-effects model was fitted to determine the relative importance of environmental factors and fire-return interval on mortality for the species. Results: From an initial total of 1313 live trees in historical photographs, 74% had died and only 44 (3.4%) had recruited in the repeat photographs, leaving 387 live individuals. Juveniles (mature adults) had decreased (increased) from 27% (73%) to 8% (92%) over the intervening period. Our model demonstrates that mortality is related to greater fire frequency, higher temperatures, lower elevations, less rocky habitats and aspect (i.e. east-facing slopes had the least mortality). Conclusions: Our results show that W. cedarbergensis populations have declined significantly over the recorded period, with a pronounced decline in the last 30 years. Individuals that established in open habitats at lower, hotter elevations and experienced a greater fire frequency appear to be more vulnerable to mortality than individuals growing within protected, rocky environments at higher, cooler locations with less frequent fires. Climate models predict increasing temperatures for our study area (and likely increases in wildfires). If these predictions are realised, further declines in the species can be expected. Urgent management interventions, including seedling out-planting in fire-protected high elevation sites, reducing fire frequency in higher elevation populations, and assisted migration, should be considered.

Seawater carbonate chemistry and biological processes duirng experiments with bryozoan Myriapora truncata, 2010

There are serious concerns that ocean acidification will combine with the effects of global warming to cause major shifts in marine ecosystems, but there is a lack of field data on the combined ecological effects of these changes due to the difficulty of creating large-scale, long-term exposures to elevated CO2 and temperature. Here we report the first coastal transplant experiment designed to investigate the effects of naturally acidified seawater on the rates of net calcification and dissolution of the branched calcitic bryozoan Myriapora truncata (Pallas, 1766). Colonies were transplanted to normal (pH 8.1), high (mean pH 7.66, minimum value 7.33) and extremely high CO2 conditions (mean pH 7.43, minimum value 6.83) at gas vents off Ischia Island (Tyrrhenian Sea, Italy). The net calcification rates of live colonies and the dissolution rates of dead colonies were estimated by weighing after 45 days (May-June 2008) and after 128 days (July-October) to examine the hypothesis that high CO2 levels affect bryozoan growth and survival differently during moderate and warm water conditions. In the first observation period, seawater temperatures ranged from 19 to 24 °C; dead M. truncata colonies dissolved at high CO2 levels (pH 7.66), whereas live specimens maintained the same net calcification rate as those growing at normal pH. In extremely high CO2 conditions (mean pH 7.43), the live bryozoans calcified significantly less than those at normal pH. Therefore, established colonies of M. truncata seem well able to withstand the levels of ocean acidification predicted in the next 200 years, possibly because the soft tissues protect the skeleton from an external decrease in pH. However, during the second period of observation a prolonged period of high seawater temperatures (25-28 °C) halted calcification both in controls and at high CO2, and all transplants died when high temperatures were combined with extremely high CO2 levels. Clearly, attempts to predict the future response of organisms to ocean acidification need to consider the effects of concurrent changes such as the Mediterranean trend for increased summer temperatures in surface waters. Although M. truncata was resilient to short-term exposure to high levels of ocean acidification at normal temperatures, our field transplants showed that its ability to calcify at higher temperatures was compromised, adding it to the growing list of species now potentially threatened by global warming.

Migration and Residence Patterns of Salmonids in Puget Sound, Washington

Thesis (Ph.D.)--University of Washington, 2016-08

E-cigarette puffing patterns associated with high and low nicotine e-liquid strength: effects on toxicant and carcinogen exposure

Contrary to intuition, use of lower strength nicotine e-liquids might not offer reduced health risk if compensatory puffing behaviour occurs. Compensatory puffing (e.g. more frequent, longer puffs) or user behaviour (increasing the wattage) can lead to higher temperatures at which glycerine and propylene glycol (solvents used in e-liquids) undergo decomposition to carbonyl compounds, including the carcinogens formaldehyde and acetaldehyde. This study aims to document puffing patterns and user behaviour associated with using high and low strength nicotine e-liquid and associated toxicant/carcinogen exposure in experienced e-cigarette users (known as vapers herein).

Functional alkali tantalate 2D structures for microelectronics and related applications

Alkali tantalates and niobates, including K(Ta / Nb)O3, Li(Ta / Nb)O3 and Na(Ta / Nb)O3, are a very promising ferroic family of lead-free compounds with perovskite-like structures. Their versatile properties make them potentially interesting for current and future application in microelectronics, photocatalysis, energy and biomedics. Among them potassium tantalate, KTaO3 (KTO), has been raising interest as an alternative for the well-known strontium titanate, SrTiO3 (STO). KTO is a perovskite oxide with a quantum paraelectric behaviour when electrically stimulated and a highly polarizable lattice, giving opportunity to tailor its properties via external or internal stimuli. However problems related with the fabrication of either bulk or 2D nanostructures makes KTO not yet a viable alternative to STO. Within this context and to contribute scientifically to the leverage tantalate based compounds applications, the main goals of this thesis are: i) to produce and characterise thin films of alkali tantalates by chemical solution deposition on rigid Si based substrates, at reduced temperatures to be compatible with Si technology, ii) to fulfil scientific knowledge gaps in these relevant functional materials related to their energetics and ii) to exploit alternative applications for alkali tantalates, as photocatalysis. In what concerns the synthesis attention was given to the understanding of the phase formation in potassium tantalate synthesized via distinct routes, to control the crystallization of desired perovskite structure and to avoid low temperature pyrochlore or K-deficient phases. The phase formation process in alkali tantalates is far from being deeply analysed, as in the case of Pb-containing perovskites, therefore the work was initially focused on the process-phase relationship to identify the driving forces responsible to regulate the synthesis. Comparison of phase formation paths in conventional solid-state reaction and sol-gel method was conducted. The structural analyses revealed that intermediate pyrochlore K2Ta2O6 structure is not formed at any stage of the reaction using conventional solid-state reaction. On the other hand in the solution based processes, as alkoxide-based route, the crystallization of the perovskite occurs through the intermediate pyrochlore phase; at low temperatures pyrochlore is dominant and it is transformed to perovskite at >800 °C. The kinetic analysis carried out by using Johnson-MehlAvrami-Kolmogorow model and quantitative X-ray diffraction (XRD) demonstrated that in sol-gel derived powders the crystallization occurs in two stages: i) at early stage of the reaction dominated by primary nucleation, the mechanism is phase-boundary controlled, and ii) at the second stage the low value of Avrami exponent, n ~ 0.3, does not follow any reported category, thus not permitting an easy identification of the mechanism. Then, in collaboration with Prof. Alexandra Navrotsky group from the University of California at Davis (USA), thermodynamic studies were conducted, using high temperature oxide melt solution calorimetry. The enthalpies of formation of three structures: pyrochlore, perovskite and tetragonal tungsten bronze K6Ta10.8O30 (TTB) were calculated. The enthalpies of formation from corresponding oxides, ∆Hfox, for KTaO3, KTa2.2O6 and K6Ta10.8O30 are -203.63 ± 2.84 kJ/mol, - 358.02 ± 3.74 kJ/mol, and -1252.34 ± 10.10 kJ/mol, respectively, whereas from elements, ∆Hfel, for KTaO3, KTa2.2O6 and K6Ta10.8O30 are -1408.96 ± 3.73 kJ/mol, -2790.82 ± 6.06 kJ/mol, and -13393.04 ± 31.15 kJ/mol, respectively. The possible decomposition reactions of K-deficient KTa2.2O6 pyrochlore to KTaO3 perovskite and Ta2O5 (reaction 1) or to TTB K6Ta10.8O30 and Ta2O5 (reaction 2) were proposed, and the enthalpies were calculated to be 308.79 ± 4.41 kJ/mol and 895.79 ± 8.64 kJ/mol for reaction 1 and reaction 2, respectively. The reactions are strongly endothermic, indicating that these decompositions are energetically unfavourable, since it is unlikely that any entropy term could override such a large positive enthalpy. The energetic studies prove that pyrochlore is energetically more stable phase than perovskite at low temperature. Thus, the local order of the amorphous precipitates drives the crystallization into the most favourable structure that is the pyrochlore one with similar local organization; the distance between nearest neighbours in the amorphous or short-range ordered phase is very close to that in pyrochlore. Taking into account the stoichiometric deviation in KTO system, the selection of the most appropriate fabrication / deposition technique in thin films technology is a key issue, especially concerning complex ferroelectric oxides. Chemical solution deposition has been widely reported as a processing method to growth KTO thin films, but classical alkoxide route allows to crystallize perovskite phase at temperatures >800 °C, while the temperature endurance of platinized Si wafers is ~700 °C. Therefore, alternative diol-based routes, with distinct potassium carboxylate precursors, was developed aiming to stabilize the precursor solution, to avoid using toxic solvents and to decrease the crystallization temperature of the perovskite phase. Studies on powders revealed that in the case of KTOac (solution based on potassium acetate), a mixture of perovskite and pyrochlore phases is detected at temperature as low as 450 °C, and gradual transformation into monophasic perovskite structure occurs as temperature increases up to 750 °C, however the desired monophasic KTaO3 perovskite phase is not achieved. In the case of KTOacac (solution with potassium acetylacetonate), a broad peak is detected at temperatures <650 °C, characteristic of amorphous structures, while at higher temperatures diffraction lines from pyrochlore and perovskite phases are visible and a monophasic perovskite KTaO3 is formed at >700 °C. Infrared analysis indicated that the differences are due to a strong deformation of the carbonate-based structures upon heating. A series of thin films of alkali tantalates were spin-coated onto Si-based substrates using diol-based routes. Interestingly, monophasic perovskite KTaO3 films deposited using KTOacac solution were obtained at temperature as low as 650 °C; films were annealed in rapid thermal furnace in oxygen atmosphere for 5 min with heating rate 30 °C/sec. Other compositions of the tantalum based system as LiTaO3 (LTO) and NaTaO3 (NTO), were successfully derived as well, onto Si substrates at 650 °C as well. The ferroelectric character of LTO at room temperature was proved. Some of dielectric properties of KTO could not be measured in parallel capacitor configuration due to either substrate-film or filmelectrode interfaces. Thus, further studies have to be conducted to overcome this issue. Application-oriented studies have also been conducted; two case studies: i) photocatalytic activity of alkali tantalates and niobates for decomposition of pollutant, and ii) bioactivity of alkali tantalate ferroelectric films as functional coatings for bone regeneration. Much attention has been recently paid to develop new type of photocatalytic materials, and tantalum and niobium oxide based compositions have demonstrated to be active photocatalysts for water splitting due to high potential of the conduction bands. Thus, various powders of alkali tantalates and niobates families were tested as catalysts for methylene blue degradation. Results showed promising activities for some of the tested compounds, and KNbO3 is the most active among them, reaching over 50 % degradation of the dye after 7 h under UVA exposure. However further modifications of powders can improve the performance. In the context of bone regeneration, it is important to have platforms that with appropriate stimuli can support the attachment and direct the growth, proliferation and differentiation of the cells. In lieu of this here we exploited an alternative strategy for bone implants or repairs, based on charged mediating signals for bone regeneration. This strategy includes coating metallic 316L-type stainless steel (316L-SST) substrates with charged, functionalized via electrical charging or UV-light irradiation, ferroelectric LiTaO3 layers. It was demonstrated that the formation of surface calcium phosphates and protein adsorption is considerably enhanced for 316L-SST functionalized ferroelectric coatings. Our approach can be viewed as a set of guidelines for the development of platforms electrically functionalized that can stimulate tissue regeneration promoting direct integration of the implant in the host tissue by bone ingrowth and, hence contributing ultimately to reduce implant failure.

Efeito de fatores ambientais e tolerância a herbicidas em três espécies de plantas daninhas da família Rubiaceae

The strong selection pressure exerted by intensive use of glyphosate in cultivated areas has selected populations of the Rubiaceae weed species Borreria latifolia (Aubl.) K.Shum. (broadleaf buttonweed), Galianthe chodatiana (Standl.) E.L. Cabral (galiante) and Richardia brasiliensis Gomes (Brazilian pusley) with differential sensitivity to this herbicide in the South region of Brazil. The control of these weeds with herbicides is troublesome and signals the need to incorporate management practices of ruderal flora and crops, more sustainable and that results in more efficient control for long-term. Therefore, it is very important to expand the information about their biology and management. This study aimed: (a) select efficient methods to overcome dormancy of B. latifolia and G. chodatiana and determine how they influence the kinetics of seeds germination; (b) analyze the effects of temperature, irradiance, pH, aluminum and salinity on seed germination and initial growth of the B. latifolia, G. chodatiana e R. brasiliensis seedlings; (c) evaluate tolerance to glyphosate levels in biotypes of B. latifolia, G. chodatiana e R. brasiliensis through dose-response curves and compare two methods to evaluate herbicidal control; (d) and evaluated the effectiveness of alternative herbicides in pre-emergence and in early and late post-emergence of the three species. The treatment with KNO3 2%/3h + gibberellic acid 400 ppm resulted in higher percentage of G. chodatiana seed germination. This treatment and also the dry heat (60°C/30 min) + KNO3 2%/3h were more effective in overcoming dormancy of B. latifolia. G. chodatiana and R. brasiliensis tolerate lower temperatures during the germination process, while B. latifolia tolerate higher temperatures. B. latifolia and R. brasiliensis are positive photoblastic while G. chodatiana is indifferent to the photoperiod. B. latifolia shows higher germination and early development in pH 3, while G. chodatiana and R. brasiliensis prefer pH range between 5 and 7. B. latifolia and G. chodatiana were more tolerant to the aluminum during the germination process than R. brasiliensis. Low salt levels were sufficient to reduce the seed germination of the three species. Some biotypes of B. latifolia and R. brasiliensis showed medium-high glyphosate tolerance, not being controlled by higher doses than recommended. The G. chodatiana specie was not controlled with the highest dose used, showing a high glyphosate tolerance. The sulfentrazone, s-metolachlor and saflufenacil herbicides sprayed in pre-emergence showed high efficacy both on B. latifolia and R. brasiliensis, while chlorimuron-ethyl and diclosulan were effective only on R. brasiliensis. In early post-emergence the fomesafen, lactofem and flumioxazin herbicides efficiently controlled plants of all species, while bentazon showed high efficacy only on B. latifolia. Noteworthy the susceptibility of the G. chodatiana specie for applications in early post-emergence, because the control effectiveness and the number of effective herbicides are reduced with increasing the plant age. Many treatments with tank mix or sequencial applications with glyphosate, were effective in controlling B. latifolia and R. brasiliensis plants in advanced stage of development.

Análise bioclimática e investigação do conforto térmico em ambientes externos: uma experiência no bairro de Petrópolis em Natal/RN

This study was intended to investigate how the urban form has been influencing the changes in the climate of the city and make a correlation between the climate and the thermal sensation of the users of open spaces. The research was developed in the district of Petrópolis in Natal/ RN whose occupation has been almost consolidated. Among other reasons, this district was selected because it was planned considering the environmental aspects of comfort. The methodologies used are based on KATZSCHNER (1997) and OLIVEIRA (1988) studies, which suggest the drawing and analysis of maps of the area under study, including topography, height of the buildings, land use, green areas, and types of soil pavement, as well as measurement of the environmental variables: air temperature, relative humidity, direction and wind speed for a comparative study. As part of this, study local users of the district were interviewed about their thermal sensations in open spaces. For the statistical analysis, data was collected at 10 distinct points characterized by BUSTOS ROMERO (2002), being 8 within the district and 2 at different places (outside the district), at climatologic stations, in 3 periods (August/2000, January/2002 and June/2002), for 4 consecutive days for each measurement (from Sunday to Wednesday) at the time of lower and higher temperatures in the city, 6:00 am and 1:00 pm, respectively. At the same time interviews were carried out with users of the open spaces in the area, totaling 171 valid formularies. The urban form showed a rather leveled topography, great diversity of land use and height of the buildings, with the existence of an area mostly occupied with high buildings, very little green area and soil practically impermeable. The statistical analysis showed high temperature and humidity levels. The wind direction is predominantly Southeast with extremely variable speeds. When the data from this district is compared with the data from other areas in the city and its outskirt, it was observed that this district is hotter and less ventilated than the others; besides, most users said that they felt uncomfortable in the local environmental conditions. The results of the analysis generated a zoning for the district with recommendations for soil occupation. The profile of the user was defined regarding the thermal comfort, as well as some discussion about the comfort parameters, including the proposal of limiting areas of temperature and humidity for the thermal comfort in the open spaces

L'orientation et la propriété de mémoire de forme des polymères cristallins liquides à chaînes latérales covalents et supramoléculaires

In many studies of the side-chain liquid crystalline polymers (SCLCPs) bearing azobenzene mesogens as pendant groups, obtaining the orientation of azobenzene mesogens at a macroscopic scale as well as its control is important, because it impacts many properties related to the cooperative motion characteristic of liquid crystals and the trans-cis photoisomerization of the azobenzene molecules. Various means can be used to align the mesogens in the polymers, including rubbed surface, mechanical stretching or shearing, and electric or magnetic field. In the case of azobenzene-containing SCLCPs, another method consists in using linearly polarized light (LPL) to induce orientation of azobenzene mesogens perpendicular to the polarization direction of the excitation light, and such photoinduced orientation has been the subject of numerous studies. In the first study realized in this thesis (Chapter 1), we carried out the first systematic investigation on the interplay of the mechanically and optically induced orientation of azobenzene mesogens as well as the effect of thermal annealing in a SCLCP and a diblock copolymer comprising two SCLCPs bearing azobenzene and biphenyl mesogens, respectively. Using a supporting-film approach previously developed by our group, a given polymer film can be first stretched in either the nematic or smectic phase to yield orientation of azobenzene mesogens either parallel or perpendicular to the strain direction, then exposed to unpolarized UV light to erase the mechanically induced orientation upon the trans–cis isomerization, followed by linearly polarized visible light for photoinduced reorientation as a result of the cis–trans backisomerization, and finally heated to different LC phases for thermal annealing. Using infrared dichroism to monitor the change in orientation degree, the results of this study have unveiled complex and different orientational behavior and coupling effects for the homopolymer of poly{6-[4-(4-methoxyphenylazo)phenoxy]hexyl methacrylate} (PAzMA) and the diblock copolymer of PAzMA-block- poly{6-[4-(4-cyanophenyl) phenoxy]hexyl methacrylate} (PAzMA-PBiPh). Most notably for the homopolymer, the stretching-induced orientation exerts no memory effect on the photoinduced reorientation, the direction of which is determined by the polarization of the visible light regardless of the mechanically induced orientation direction in the stretched film. Moreover, subsequent thermal annealing in the nematic phase leads to parallel orientation independently of the initial mechanically or photoinduced orientation direction. By contrast, the diblock copolymer displays a strong orientation memory effect. Regardless of the condition used, either for photoinduced reorientation or thermal annealing in the liquid crystalline phase, only the initial stretching-induced perpendicular orientation of azobenzene mesogens can be recovered. The reported findings provide new insight into the different orientation mechanisms, and help understand the important issue of orientation induction and control in azobenzene-containing SCLCPs. The second study presented in this thesis (Chapter 2) deals with supramolecular side-chain liquid crystalline polymers (S-SCLCPs), in which side-group mesogens are linked to the chain backbone through non-covalent interactions such as hydrogen bonding. Little is known about the mechanically induced orientation of mesogens in S-SCLCPs. In contrast to covalent SCLCPs, free-standing, solution-cast thin films of a S-SCLCP, built up with 4-(4’-heptylphenyl) azophenol (7PAP) H-bonded to poly(4-vinyl pyridine) (P4VP), display excellent stretchability. Taking advantage of this finding, we investigated the stretching-induced orientation and the viscoelastic behavior of this S-SCLCP, and the results revealed major differences between supramolecular and covalent SCLCPs. For covalent SCLCPs, the strong coupling between chain backbone and side-group mesogens means that the two constituents can mutually influence each other; the lack of chain entanglements is a manifestation of this coupling effect, which accounts for the difficulty in obtaining freestanding and mechanically stretchable films. Upon elongation of a covalent SCLCP film cast on a supporting film, the mechanical force acts on the coupled polymer backbone and mesogenic side groups, and the latter orients cooperatively and efficiently (high orientation degree), which, in turn, imposes an anisotropic conformation of the chain backbone (low orientation degree). In the case of the S-SCLCP of P4VP-7PAP, the coupling between the side-group mesogens and the chain backbone is much weakened owing to the dynamic dissociation/association of the H-bonds linking the two constituents. The consequence of this decoupling is readily observable from the viscoelastic behavior. The average molecular weight between entanglements is basically unchanged in both the smectic and isotropic phase, and is similar to non-liquid crystalline samples. As a result, the S-SCLCP can easily form freestanding and stretchable films. Furthermore, the stretching induced orientation behavior of P4VP-7PAP is totally different. Stretching in the smectic phase results in a very low degree of orientation of the side-group mesogens even at a large strain (500%), while the orientation of the main chain backbone develops steadily with increasing the strain, much the same way as amorphous polymers. The results imply that upon stretching, the mechanical force is mostly coupled to the polymer backbone and leads to its orientation, while the main chain orientation exerts little effect on orienting the H-bonded mesogenic side groups. This surprising finding is explained by the likelihood that during stretching in the smectic phase (at relatively higher temperatures) the dynamic dissociation of the H-bonds allow the side-group mesogens to be decoupled from the chain backbone and relax quickly. In the third project (Chapter 3), we investigated the shape memory properties of a S-SCLCP prepared by tethering two azobenzene mesogens, namely, 7PAP and 4-(4'-ethoxyphenyl) azophenol (2OPAP), to P4VP through H-bonding. The results revealed that, despite the dynamic nature of the linking H-bonds, the supramolecular SCLCP behaves similarly to covalent SCLCP by exhibiting a two-stage thermally triggered shape recovery process governed by both the glass transition and the LC-isotropic phase transition. The ability for the supramolecular SCLCP to store part of the strain energy above T[subscript g] in the LC phase enables the triple-shape memory property. Moreover, thanks to the azobenzene mesogens used, which can undergo trans-cis photoisomerization, exposure the supramolecular SCLCP to UV light can also trigger the shape recovery process, thus enabling the remote activation and the spatiotemporal control of the shape memory. By measuring the generated contractile force and its removal upon turning on and off the UV light, respectively, on an elongated film under constant strain, it seems that the optically triggered shape recovery stems from a combination of a photothermal effect and an effect of photoplasticization or of an order-disorder phase transition resulting from the trans-cis photoisomerization of azobenzene mesogens.

The multistage crystallization of zircon in calc-alkaline granitoids : U-Pb age constraints on the timing of Variscan tectonic activity in SW Iberia

CL imaging and U–Th–Pb data for a population of zircons from two of the Évora Massif granitoids (Ossa-Morena Zone, SW Iberia) show that both calc-alkaline granitoids have zircon populations dominated by grains with cores and rims either showing or not showing differences in Th/U ratio, and having ages in the range ca. 350–335 Ma (Early Carboniferous). Multistage crystallization of zircon is revealed in two main growth stages (ca. 344–342 Ma and ca. 336–335 Ma), well represented by morphologically complex zircons with cores and rims with different ages and different Th/U ratios that can be explained by: (1) crystallization from melts with different compositions (felsic peraluminous to felsic-intermediate metaluminous; 0.001 Th/U ratio < 0.5) and (2) transient temperature fluctuations in a system where anatectic felsic melts periodically underwent injection of more mafic magmas at higher temperatures. The two studied calc-alkaline granitoids do not include inherited zircons (pre-Carboniferous), probably because they were formed at the highest grade of metamorphism (T 837 °C; granulite facies) and/or because they were derived from inheritance-poor felsic and mafic rocks from a previous cycle, as suggested by the internal structures of zircon cores. These Variscan magmatic rocks with crystallization ages estimated at ca. 336–335 Ma are spatially and temporally related to high-temperature metamorphism, anatexis, processes of interaction between crustal- and mantle-derived magmas and intra-orogenic extension that acted in SW Iberia during the Early Carboniferous.

Produção de lipidios funcionais por ação de lipase fúngica

A modificação estrutural de óleos e gorduras é uma das principais áreas de interesse de pesquisa em diferentes setores industriais. No caso da indústria de alimentos, a interesterificação é empregada para melhorar propriedades nutricionais e funcionais, em que se obtêm compostos diferentes dos que lhes deram origem. As lipases microbianas são os biocatalisadores mais utilizados industrialmente, por serem mais estáveis, específicas e com propriedades bem mais diversificadas que as lipases de outras fontes. Este trabalho objetivou, primeiramente, a caracterização da gordura da pele de frango (GPF) e sua comparação com óleo de soja, como referência, visando a utilização de GPF em reações de interesterificação. Para isto foram caracterizados quanto aos índices de rancidez hidrolítica e oxidativa, bem como de matéria insaponificável, índices de saponificação, refração e iodo. Foi realizado ainda o fracionamento e perfil de ácidos graxos destes lipídios e suas frações, com o cálculo de seus índices nutricionais. Foi verificado que a GPF apresentou qualidade satisfatória devido aos baixos índices de acidez (0,65 g ácido oleico.100 g -1 ), peróxido (2,14 meq.kg-1 ), p-anisidina (0,70 unidades de absorvância.g-1 ), além de fonte de ácidos graxos mono-insaturados (40%), sendo fonte promissora para estudos de interesterificação. Em um segundo momento o objetivo foi produzir lipídios modificados ricos em ácidos graxos essenciais a partir da gordura da pele de frango e ácidos graxos ramificados, utilizando lipase sn-1,3 específica e interesterificação do tipo acidólise. Foram estudados os fatores concentração de enzima, adição de água, proporção de substratos e tempo, segundo um planejamento experimental fatorial completo 2 4 . As separações analíticas foram executadas em placas de cromatografia de camada delgada, sendo as frações posteriormente extraídas, ressuspensas e injetadas no cromatógrafo a gás. Foi verificado que a adição de água ao meio reacional apresentou efeito significativo (p<0,05) para todos ácidos graxos avaliados dos triacilgliceróis, sendo que para o ácido essencial linoleico (C18:2) o efeito do tempo de reação também foi significativo, sendo verificado que quanto maior o tempo de reação, menor a quantidade de água a ser adicionada. Em um terceiro momento, o objetivo foi produzir éster fenólico a partir do DHCA, além de realizar reações de transesterificação deste éster com tricaprilina. Para a reação de transesterificação, foi utilizado um delineamento composto central rotacional (DCCR) variando a quantidade de enzima, tempo de reação e temperatura sobre a resposta (%) dos reagentes consumidos. A lipase Novozym® 435 de Candida antarctica foi utilizada como catalisador de todas reações. Foi verificado que a maior produção de éster (50%) ocorreu em oito dias. Nas reações de transesterificação, as relações molares em que houve maior consumo do éster produzido foram 1:5 e 1:10, sendo obtidos 21,1% e 29,6% de residual de dihidrocafeato de octila, respectivamente em 24 h. Foi observado que em altas temperaturas e tempo superior a 26 h, houve o menor residual de dihidrocafeato de octila (18,2%). Foram identificados três diferentes compostos fenólicos, contendo em sua estrutura dihidrocafeato de octila e ácido caprílico.