Adhesive Quality of Self-adhesive and Conventional Adhesive Resin Cement to Y-TZP Ceramic Before and After Aging Conditions

Purpose: This study evaluated the adhesive quality of simplified self-adhesive and conventional resin cements to Y-TZP in dry and aged conditions. Methods: Y-TZP ceramic blocks (N=192) (5 x 5 x 2 mm) were embedded in acrylic resin and randomly divided into two groups, based on surface conditioning: 96% isopropanol or chairside tribochemical silica coating and silanization. Conditioned ceramics were divided into four groups to receive the resin cements (Panavia F 2.0, Variolink II, RelyX U100 and Maxcem). After 24 hours, half of the specimens (n=12) from each group were submitted to shear bond strength testing (0.5 nun/minute). The remaining specimens were tested after 90 days of water storage at 37 degrees C and thermocycling (12,000x, 5 degrees C-55 degrees C). Failure types were then assessed. The data were analyzed using three-way ANOVA and the Tukey's test (alpha=0.05). Results: Significant effects of ceramic conditioning, cement type and storage conditions were observed (p<0.0001). The groups cleaned using alcohol only showed low bond strength values in dry conditions and the bond strength was reduced dramatically after aging. Groups conditioned using silica coating and silanization showed higher bond strengths both in dry and aged conditions. A high number of specimens failed prematurely prior to testing when they were cleaned using 96% isopropanol. Conclusion: Overall, silica coating and silanization showed higher, stable bond strengths with and without aging. The durability of resin-ceramic adhesion varied, depending on the adhesive cement type.

Las exigencias educativas de la sociedad actual y el derecho a la educación en América Latina = Educational needs in a modern society and the right to education in Latin America

Incluye Bibliografía

The right to an identity: birth registration in Latin America and the Caribbean

A disturbing token of child and adolescent vulnerability in Latin America and the Caribbean is that so many are deprived of any legal identity by failure to report their birth. This bars them from exercising basic citizen rights and can hinder their access to productive employment, social benefits and the justice system and deny them recognition as full citizens and the right to well-being, capacity development and political participation.

The right of children and adolescents to a healthy environment. A diagnosis from Latin America and the Caribbean

Healthy environment: unresolved debts that affect childhood and adolescenceIn this new edition, we point out the right of children and adolescents to live in a healthy environment with emphasis on adequate access to drinking water and sanitation, including diagnosis as well as policy perspective. It is our contribution to the challenges set out by the Millennium Development Goals and the Convention on the Rights of the Child.

The right to education: An unfinished task for Latin America and the Caribbean

The right to education.Our newsletter once again takes on the challenges set forth by the Millennium Declaration and the human rights approach embedded in the Convention on the Rights of the Child. In this issue, we will examine the right of children and adolescents to education.

Respiratory responses of the tropical millipede Plusioporus setiger (Broelemann, 1902) (Spirostreptida: Spirostreptidae) to normoxic and hypoxic conditions

1. 1. Oxygen consumption and its relationship to declining oxygen tension was examined in the tropical spirotreptid millipede, Plusioporus setiger. 2. 2. At 25°C and normoxia, the allometric equations relating the weight-specific oxygen consumption rates and body weight were V ̇O2 = 2.1266 × W-53 for males, and V ̇O2 = 2.0915 × W-64 for females, but no significant difference was detected from the b-values. 3. 3. Plusioporus setiger regulated respiration down to 35.40 mmHg O2 when suddenly exposed to a lowered oxygen tension, or 17.70 mmHg O2, when examined in a stepwise declining oxygen tension. 4. 4. O2 dependence indices ( K1 K2) were relatively low, also expressing regulation, but no relation to size (weight) was recorded. 5. 5. After exposure to hypoxia, P. setiger showed a typical pattern of under repayment, on the return to normoxia. © 1987.

Fermentation medium and oxygen transfer conditions that maximize the xylose conversion to ethanol by Pichia stipitis

The xylose conversion to ethanol by Pichia stipitis was studied. In a first step, the necessity of supplementing the fermentation medium with urea. MgSO(4) x 7H(2)O, and/or yeast extract was evaluated through a 2(3) full factorial design. The simultaneous addition of these three nutritional sources to the fermentation medium, in concentrations of 2.3, 1.0, and 3.0 g/l, respectively, showed to be important to improve the ethanol production in detriment of the substrate conversion to cell. In a second stage, fermentation assays performed in a bioreactor under different K(L)a (volumetric oxygen transfer coefficient) conditions made possible understanding the influence of the oxygen transfer on yeast performance, as well as to define the most suitable range of values for an efficient ethanol production. The most promising region to perform this bioconversion process was found to be between 2.3 and 4.9 h(-1), since it promoted the highest ethanol production results with practically exhaustion of the xylose from the medium. These findings contribute for the development of an economical and efficient technology for large scale production of second generation ethanol. (C) 2011 Elsevier Ltd. All rights reserved.

Interannual variation in commercial oyster (Crassostrea gigas) farming in the sea (Florianopolis, Brazil, 27 degrees 44 ' S; 48 degrees 33 ' W) in relation to temperature, chlorophyll a and associated oceanographic conditions

Aquaculture of filter-feeding bivalve mollusks involves the fruitful conversion of marine particulate organic matter into premium protein of high nutritive value. Culture performance of bivalves is largely dependent on hydrological conditions and directly affected by e. g. temperature and chlorophyll levels. Accordingly, these parameters may be related with seasonality but also with oceanographic features combined with climate events. Yields of Pacific cupped oyster (Crassostrea gigas) reared at commercial procedures in suspended structures (long-lines) in a sheltered bay in Southern Brazil (Santa Catarina State, 27S 43'; 48 W 30') were evaluated in relation to local environmental conditions: sea surface temperature, chlorophyll a concentration, and associate effects of cold fronts events and El Nino and La Nina periods. Outputs from four consecutive commercial crop years were analyzed (2005/06, 2006/07, 2007/08, 2008/09) in terms of oyster survival and development time during the following grow-out phases of the culture cycle: seed to juvenile, juvenile to adult, adult to marketable. Since culture management and genetics were standardized significant differences verified among crop performance could be mostly related to environmental effects. Time series of temperature and chlorophyll a (remote sensing data) from crop periods displayed significant seasonal and interannual variation. As expected, performance during initial grow-out stages (seed to juvenile) was critical for final crop yield. Temperature was the main factor affecting survival in these initial stages with a trend of negative correlation, though not statistically significant. On the other hand, oyster development rate was significantly and positively affected by chlorophyll a concentration. Chlorophyll a values could be increased by upwelled cold nutrient-rich South Atlantic Central Water (SACW, related to predominant Northern winds) though further dependent on occurrence of Southern winds (cold fronts) to assist seawater penetration into the sheltered farming area. Lower salinity nutrient-rich northward drifted waters from La Plata River discharge may also result in chlorophyll a rise in the farming area. The El Nino period (July 2006 to February 2007) coincided with lower chlorophyll a levels in the farming site that may be related to both decreased number of cold fronts as well as predominance of Northern winds that retain northward spreading of La Plata River discharge waters. In contrast, the La Nina period (August 2007 to June 2008) corresponded to higher chlorophyll a values in the farming area by both upwelling of SACW and penetration of La Plata River discharge water assisted by increased occurrence of Southern winds and cold fronts. The recognition of the potentially changing climate and effects upon the environment will be an important step in planning future development of bivalve aquaculture.

Changes in phytoplankton composition in response to tides, wind-induced mixing conditions, and freshwater outflows in an urbanised estuarine complex

Recent reports have shown an increase in potentially harmful phytoplankton in Santos bay (Southeastern Brazilian Coast), located in a highly urbanised estuarine complex. Prediction of blooms is, thus, essential but the phytoplankton community structure in very dynamic regions is difficult to determine. In the present work, we discriminate bloom forming microphytoplankton dominance and their relationship to physical and meteorological variables to look for patterns observed in different tides and seasons. Comparing 8 distinct situations, we found five scenarios of dominance that could be related to winds, tides and rainfall: i) Surfers, diatoms occurring during high surf zone energies; ii) Sinkers, represented by larger celled diatoms during spring tide, after periods of high precipitation rates; iii) Opportunistic mixers, composed of chain forming diatoms with small or elongate cells occurring during neap tides; iv) Local mixers, microplanktonic diatoms and dinoflagellates which occurred throughout the 298 sampling stations; and v) Mixotrophic dinoflagellates, after intense estuarine discharges. Results suggest alterations in the temporal patterns for some bloom-forming species, while others appeared in abundances above safe limits for public health. This approach can also illustrate possible impacts of changes in freshwater discharge in highly urbanised estuaries.

Physical and mineralogical changes of Hungarian monumental stones exposed to different conditions: stone-testing in-situ and under laboratory conditions

The Székesfehérvár Ruin Garden is a unique assemblage of monuments belonging to the cultural heritage of Hungary due to its important role in the Middle Ages as the coronation and burial church of the Kings of the Hungarian Christian Kingdom. It has been nominated for “National Monument” and as a consequence, its protection in the present and future is required. Moreover, it was reconstructed and expanded several times throughout Hungarian history. By a quick overview of the current state of the monument, the presence of several lithotypes can be found among the remained building and decorative stones. Therefore, the research related to the materials is crucial not only for the conservation of that specific monument but also for other historic structures in Central Europe. The current research is divided in three main parts: i) description of lithologies and their provenance, ii) physical properties testing of historic material and iii) durability tests of analogous stones obtained from active quarries. The survey of the National Monument of Székesfehérvár, focuses on the historical importance and the architecture of the monument, the different construction periods, the identification of the different building stones and their distribution in the remaining parts of the monument and it also included provenance analyses. The second one was the in situ and laboratory testing of physical properties of historic material. As a final phase samples were taken from local quarries with similar physical and mineralogical characteristics to the ones used in the monument. The three studied lithologies are: fine oolitic limestone, a coarse oolitic limestone and a red compact limestone. These stones were used for rock mechanical and durability tests under laboratory conditions. The following techniques were used: a) in-situ: Schmidt Hammer Values, moisture content measurements, DRMS, mapping (construction ages, lithotypes, weathering forms) b) laboratory: petrographic analysis, XRD, determination of real density by means of helium pycnometer and bulk density by means of mercury pycnometer, pore size distribution by mercury intrusion porosimetry and by nitrogen adsorption, water absorption, determination of open porosity, DRMS, frost resistance, ultrasonic pulse velocity test, uniaxial compressive strength test and dynamic modulus of elasticity. The results show that initial uniaxial compressive strength is not necessarily a clear indicator of the stone durability. Bedding and other lithological heterogeneities can influence the strength and durability of individual specimens. In addition, long-term behaviour is influenced by exposure conditions, fabric and, especially, the pore size distribution of each sample. Therefore, a statistic evaluation of the results is highly recommended and they should be evaluated in combination with other investigations on internal structure and micro-scale heterogeneities of the material, such as petrographic observation, ultrasound pulse velocity and porosimetry. Laboratory tests used to estimate the durability of natural stone may give a good guidance to its short-term performance but they should not be taken as an ultimate indication of the long-term behaviour of the stone. The interdisciplinary study of the results confirms that stones in the monument show deterioration in terms of mineralogy, fabric and physical properties in comparison with quarried stones. Moreover stone-testing proves compatibility between quarried and historical stones. Good correlation is observed between the non-destructive-techniques and laboratory tests results which allow us to minimize sampling and assessing the condition of the materials. Concluding, this research can contribute to the diagnostic knowledge for further studies that are needed in order to evaluate the effect of recent and future protective measures.

The Right to Voice: Its Realization by Estonian and American Parents in Public Schools

Investigating parents’ formal engagement opportunities in public schools serves well to characterize the relationship between states and societies. While the relationship between parental involvement and students’ academic success has been thoroughly investigated, rarely has it been seen to indicate countries’ governing regimes. The researcher was curious to see whether and how does parents’ voice differ in different democracies. The hypothesis was that in mature regimes, institutional opportunities for formal parental engagement are plenty and parents are actively involved; while in young democracies there are less opportunities and the engagement is lower. The assumption was also that parental deliberation in expressing their dissatisfaction with schools differs across democracies: where it is more intense, there it translates to higher engagement. Parents’ informedness on relevant regulations and agendas was assumed to be equally average, and their demographic background to have similar effects on engagement. The comparative, most different systems design was employed where public middle schools last graders’ parents in Tartu, Estonia and in Huntsville, Alabama the United States served as a sample. The multidimensional study includes the theoretical review, country and community analyses, institutional analysis in terms of formal parental involvement, and parents’ survey. The findings revealed sizeable differences between parents’ engagement levels in Huntsville and Tartu. The results indicate passivity in both communities, while in Tartu the engagement seems to be alarmingly low. Furthermore, Tartu parents have much less institutional opportunities to engage. In the United States, multilevel efforts to engage parents are visible from local to federal level, in Estonia similar intentions seem to be missing and meaningful parental organizations do not exist. In terms of civic education there is much room for development in both countries. The road will be longer for a young democracy Estonia in transforming its institutional systems from formally democratic to inherently inclusive.