Post-synthesis incorporation of Al into germanosilicate ITH zeolites : the influence of treatment conditions on the acidic properties and catalytic behavior in tetrahydropyranylation

M. S. thanks the Czech Science Foundation for support through the project 14-30898P. M. O. acknowledges the Czech Science Foundation for the project 13-17593P. R. E. M. thanks the EPSRC for funding (EP/K025112/1 and EP/L014475/1).Post-synthesis alumination of germanosilicate medium-pore ITH zeolites was shown to be an effective procedure for tuning their acidity. Treatment of ITH zeolites synthesized with different chemical compositions (i.e. Si/Ge = 2.5, 4.4 and 5.8) with aqueous Al(NO3)3 solution led to the formation of strong Brønsted and Lewis acid sites and an increasing fraction of ultramicro- and meso-pores in Ge-rich ITH samples (Si/Ge = 2.5 and 4.4). The concentration of Al incorporated into the framework increases with decreasing Si/Ge ratio of the parent ITH. The increasing temperature of alumination from 80 to 175 °C (HT conditions) resulted in (1) a 1.5-2-fold increase in the concentration of Brønsted acid sites formed and (2) a decreasing fraction of framework Al atoms detectable with base probe molecules (i.e. pyridine, 2,6-di-tert-butylpyridine), i.e. an increased concentration of the "inner" acid sites. The activity of prepared Al-substituted ITH zeolites in tetrahydropyranylation of alcohols is enhanced with increasing amount of accessible acid sites in bulky crystals (e.g. alumination at lower temperature) or with increasing total concentration of acid centres within tiny ITH crystals (e.g. alumination under HT conditions). This trend became more prominent with increasing kinetic diameter of the substrate molecules under investigation (methanol <1-propanol <1-hexanol).PostprintPeer reviewe

Relationship between polymorphism of growth hormone and precocity traits in Nellore heifers

Avaliaram-se as relações entre o polimorfismo do gene do hormônio do crescimento (GH) e as características de precocidade, em novilhas da raça Nelore. Amostras de sangue periférico foram obtidas de 181 animais de três rebanhos distintos do estado da Bahia, nas quais foi realizada a extração de DNA e a amplificação por PCR, seguidas por digestão com enzima de restrição AluI. Os fragmentos resultantes da digestão enzimática foram analisados em gel de agarose 2% para determinação dos respectivos genótipos. A frequência do alelo Leu nas amostras analisadas foi estimada em 100%. Em decorrência da alta incidência de homozigose para o alelo Leu, sugere-se que o restriction fragment lenght polymorphism AluI do gene GH não possa ser considerado como marcador molecular para precocidade sexual em novilhas Nelore nesses rebanhos.The relationships between polymorphism of growth hormone gene (GH) and precocity traits in Nellore heifers were evaluated. A total of 181 animals from three different farms of Bahia state, Brazil, were blood sampled. The DNA of each animal was extracted, amplified by PCR, and digested by "AluI" restriction enzyme, and the resultant fragments were analyzed in 2% agarose gel for genotype identification. The frequency of Leu allele in the analyzed samples was estimated in 100%. Due to the high incidence of homozygose for the Leu allele, it is suggested that the restriction fragment lenght polymorphism AluI of GH gene can not be considered as a molecular marker for sexual precocity in Nellore heifers of those herds.Fundação de Amparo à Pesquisa do Estado da Bahia (FAPESB)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Secure Virtual Network Embedding in a Multi-Cloud Environment

Recently-proposed virtualization platforms give Cloud users the freedom to specify their network topologies and addressing schemes. These platforms have, however, been targeting a single datacenter of a cloud provider, which is insufficient to support (critical) applications that need to be deployed across multiple trust domains while enforcing diverse security requirements. This paper addresses this problem by presenting a novel solution for a central component of network virtualization –the online network embedding, which finds efficient mappings of virtual networks requests onto the substrate network. Our solution considers security as a first class citizen, enabling the definition of flexible policies in three central areas: on the communications, where alternative security compromises can be explored (e.g.,encryption); on the computations, supporting redundancy if necessary while capitalizing on hardware assisted trusted executions; across multiples clouds, including public and private facilities, with the associated trust levels. We formulate the solution as a Mixed Integer Linear Program (MILP), and evaluate our proposal against the most commonly used alternative. Our analysis gives insight into the trade-offs involved with the inclusion of security and trust into network virtualization, providing evidence that this notion may enhance profits under the appropriate cost models

Sodium reduction by hyposodic salt on quality and chemical composition of hamburgers

This work evaluated the effect of NaCl reduction on the quality and sensorial attributes of hamburgers. Three treatments were tested: control (CON), 100% NaCl; reduction of 25% NaCl (T25), and one with 50% NaCl (T50). The pH, color, lipid oxidation, cooking losses, and texture were analyzed during 120 days of freezing storage. Chemical composition and sensory analyses were performed. The chemical composition was similar for all treatments. The pH value remained within acceptable limits throughout storage. The color, lipid oxidation, cooking losses, and texture were not influenced by the sodium replacement and freezing storage. Sensorial acceptability was also not influenced by sodium reduction. Thus, the results indicated that up to 50% replacement of NaCl by KCl could be carried out in hamburger production without altering the quality and sensorial acceptability

Incidence Patterns and Trends of non-Central Nervous System Solid Tumours in Children and Adolescents. A Collaborative Study of the Spanish Population Based Cancer Registries

Objective: To describe incidence patterns and trends in children (0-14 years) and adolescents (15-19 age-range) with solid tumours, except those of central nervous system (CNS), in Spain. Methods: Cases were drawn from eleven Spanish population-based cancer registries. Incidence was estimated for the period 1983-2007 and trends were evaluated using Joinpoint regression analysis. Results: The studied tumour groups accounted for 36% of total childhood cancers and 47.6% of those diagnosed in adolescence with annual rates per million of 53.5 and 89.3 respectively. In children 0 to 14 years of age, Neuroblastoma (NB) was the commonest (7.8%) followed by Soft-tissue sarcomas (STS) (6.3%), bone tumours (BT) (6.2%) and renal tumours (RT) (4.5%). NB was the most frequently diagnosed tumour before the 5th birthday, while STS and BT were the commonest at 5-9 years of age, and BT and Carcinoma and other epithelial tumours (COET) at 10-14. COET presented the highest incidence in adolescents, followed by germ-cell tumours (GCT), BT and STS. These four diagnostic groups accounted for 94% of total non-CNS solid tumours, in adolescents. Overall incidence rates increased significantly in children up to 1996 with an annual percentage change (APC) of 2.6% (95% CI: 1.7; 3.6). NB and COET showed significant time trend (APCs: 1.4% and 3.8% respectively) while other tumour groups such as RT, STS, BT or GCT had no significant changes over time. A significant increase was present in NB under the age of 5 and in BT and STS in children aged 10-14 years. In adolescents there were significant increases for all tumours combined (APC=2.7; 95% CI: 1.8-3.6) and for STS, GCT and COET (APCs: 3.2%, 4.4% and 3.5% respectively), while other tumour groups such as hepatic tumours, BT or thyroid carcinomas showed a decreasing trend or no increase. Conclusions: Overall, the incidence of the studied cancers in children increased along the period 1983-1996 with no posterior significant rise, while the incidence in adolescents increased significantly over the whole period 1983-2007. Several specific tumour groups showed significant rises or decrements in childhood or adolescence, although the small number of cases precludes showing significant trends or inflexion points

Analysis of Syngas Production from Catalytic Biogas Reforming and Upgrading

The development of alternative and sustainable technologies for the production of liquid biofuels has gained ground worldwide. Biogas is one of the most potential feedstocks to be used and the Fischer-Tropsch (FT) route is one of the most studied processes for the production of these liquid biofuels. In this work, different processes for the conversion of biogas to syngas by catalytic reforming were studied, in order to evaluate the better route to obtain the syngas and its usage as feedstock in FT synthesis. Two steps were analyzed using Aspen Plus V12.1®: 1) biogas upgrading; and 2) catalytic reforming process. Dry reforming (DR) and Bi reforming (BR) were selected for the reforming process assessment. CH4 and CO2 conversions were selected to evaluate the process performance. Results showed that water scrubbing is a better route to perform biogas upgrading, based on the H2S final content and the CH4 recovery. Besides, for the biogas reforming process, all scenarios presented an increase in conversions when the temperature was increased. For bi reforming, which uses biogas and water steam as reactants, a decrease in the molar fraction of H2O contributed to higher CO2 conversion. The BR process with a molar ratio of CH4, CO2, and H2O at 3:2:1, respectively, at elevated temperatures and pressure of 0.1 MPa, showed the most promising combination of results for syngas production, considering environmental and operational factors. The CH4 and CO2 conversions obtained in 900 °C were 96.45% and 98.06%, respectively

Assessment of CO2 Conversion in a Biorefinery Concept: a Biomethane Plant Case Study

One of the main challenges imposed by the climate crisis is to reduce the greenhouse gases emissions while keeping high levels of social and economic development. Therefore, the deployment of process alternatives that use residues as raw materials and integrate the conversion of by-products in added value products of interest is mandatory and integrated biorefineries play a major role in this context. In this work, thermodynamic analyses were performed to assess the conversion of a residual CO2 stream captured from the flue gases of a biomethane-based thermal power plant into syngas or methane. Results showed that the syngas production from CO2 is favored at high temperatures (>700 °C), low pressures (1 bar) and low H2/CO2 ratios (e.g. 1). Conversely, methane formation is favored at lower temperatures and higher H2/CO2 ratios. Simulations were also carried out considering the conversion of an off-gas stream from a biomethane plant, with different concentrations of CH4. Considering the syngas formation, the presence of CH4 in the feed stream enhances the CO2 conversion and increases the production of CO and H2 (desired products), while decreasing H2O formation (unwanted side product), possibly due to the simultaneous occurrence of the methane bi-reforming, RWGS and methanation reactions. Therefore, from the thermodynamic point of view, the use of the off-gas from a biomethane plant for syngas production could be a potential alternative for the destination of this residual stream, converting it into interesting chemical platforms and intermediates for fuels and chemicals production

Effects of Short Range Correlations on Ca Isotopes

The effect of Short Range Correlations (SRC) on Ca isotopes is studied using a simple phenomenological model. Theoretical expressions for the charge (proton) form factors, densities and moments of Ca nuclei are derived. The role of SRC in reproducing the empirical data for the charge density differences is examined. Their influence on the depletion of the nuclear Fermi surface is studied and the fractional occupation probabilities of the shell model orbits of Ca nuclei are calculated. The variation of SRC as function of the mass number is also discussed.Comment: 11 pages (RevTex), 6 Postscript figures available upon request at [email protected] Physical Review C in prin

alpha-particle production in the scattering of 6He by 208Pb at energies around the Coulomb barrier

New experimental data from the scattering of 6He+208Pb at energies around and below the Coulomb barrier are presented. The yield of breakup products coming from projectile fragmentation is dominated by a strong group of $\alpha$ particles. The energy and angular distributions of this group have been analyzed and compared with theoretical calculations. This analysis indicates that the $\alpha$ particles emitted at backward angles in this reaction are mainly due to two-neutron transfer to weakly bound states of the final nucleus.Comment: 20 pages, 5 figures. Nuclear Physics A792 (2007) 2-1