Yeast species involved in artisanal cachaça fermentation in three stills with different technological levels in Pernambuco,Brazil

Both the taste and aroma of cachaça, an alcoholic beverage produced by yeast fermentation of sugar cane, are influenced by yeast metabolites and volatiles. The knowledge of yeast population dynamics during the fermentation process will help to establish the basis for quality control of alcoholic beverage. In the present work, the population dynamics of three fermentation processes, with differing levels of technological sophistication, were studied. Saccharomyces cerevisiae was found to be the dominant species, but Candida milleri (Candida humilis), Pichia caribbica, Pichia guilliermondii and Zygosaccharomyces fermentati (Lachancea fermentati) were also significantly involved. In addition, four new yeast species that are not represented in NCBI/EMBL nucleotide database were found. These yeasts were classified as Candida sp., Candida drosophilae-like, Candida ubatubensis-like and Zygosaccharomyces sp. In fermentation trails at laboratory scale, all species were found to contribute to the production of volatiles. Thus it is probable that product quality is strongly dependent on population dynamics during the fermentation process.     

Cure kinetics and thermomechanical properties of thermally stable photopolymerized dimethacrylates

A range of dimethacrylates with varying backbone flexibility were partially photocured to various conversions using p‐xylylene bis‐(N,N‐diethyldithiocarbamate) as a photoiniferter and their glass transition region investigated by dynamic mechanical thermal analysis. For isothermally cured samples, the final degree of conversion was found to increase as the length of the spacer group in the monomer was increased or as the crosslink density in the resin was lowered due to the reduced glass transition temperature which allowed greater mobility and, hence, higher cure. Increasing the curing temperature also resulted in a higher degree of conversion as the network was able to polymerize further before vitrification occurred. For the partially photocured samples, the glass transition temperature was raised as the degree of conversion was increased. Most of the measures of the breadth of the glass transition were found to increase with increased conversion for dimethacrylates with short or stiff backbones (TETDMA and bisGMA) while the transition breadth was independent of conversion for either a more flexible dimethacrylate (NEGDMA) or a dimethacrylate network with a lower crosslink density (50 wt % bisGMA/50 wt % PGEMA). This conclusion was generally confirmed by analysis of the viscoelastic parameters in the frequency domain. It is not clear whether these behaviors resulted from differences in the range of molecular motions available in tight networks or if they were due to spatially heterogeneous regions in the network. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3753–3766, 2003     

Formulation and characterization of ethylcellulose microparticles containing .l-alanyl- l-glutamine peptide

Context: The l-alanyl-l-glutamine peptide (AGP) has been effective to promote acute glycemia recovery during long-term insulin-induced hypoglycemia (IIH), and the oral administration of AGP is suggested to prevent prolonged hypoglycemia, such as nocturnal hypoglycemia.

Objective: Considering the ability of AGP on glycemia recovery and AGP’s fast metabolism, the aim of current study was to obtain and characterize ethylcellulose microparticles to deliver the drug for a prolonged time.

Materials and Methods: Microparticles were prepared by simple and double emulsification/hardening method and characterized by scanning electron microscopy, thermogravimetry (TG), differential scanning calorimetry (DSC), Fourier transform infra-red (FTIR) and FT-Raman spectroscopy and in vitro release.

Results and Discussion: Spherical structures with a mean diameter between 9.30?µm and 13.19?µm were formed. TG analysis showed that the thermal stability of AGP was even more increased by encapsulation with ethylcellulose. In addition, TG, DSC, FTIR and FT-Raman analyses proved that AGP was encapsulated in a molecular way. Higher values of encapsulation efficiency were observed for the microparticles prepared by double emulsification (57.83–83.67%) than for those prepared by simple emulsification (18.37%). However, the last ones could release the peptide in a quicker and more extensive manner than those prepared by double emulsification.

Conclusion: For the first time, microparticles containing AGP were developed and exhibited prolonged in vitro release as well as protection to the drug, and it could be considered as a dosage form for patients who suffer from insulin-induced hypoglycemia and/or nocturnal hypoglycemia.     

A fluorometric assay for the measurement of endothelial cell density in vitro

A fluorometric assay for determining endothelial cell numbers based on the endogenous enzyme acid phosphatase is described. In preliminary studies, three substrates--p-nitrophenyl phosphate, 4-methylumbelliferyl phosphate, and 2'-[2-benzthiazoyl]-6'-hydroxy-benthiazole phosphate (AttoPhos)--were compared with respect to their kinetic, optimum assay conditions, sensitivity, and detection limits. Only AttoPhos was found to have a high degree of sensitivity, reliability, and reproducibility for measuring both high and low cell numbers in the same plate. In subsequent experiments, assay conditions were validated for measuring endothelial cell density in response to basic fibroblast growth factor and fumagillin. Furthermore, the AttoPhos assay revealed a linear correlation between acid phosphatase activity and cell number in many cell types, including BALB/3T3, CHO-K1, A431, MCF7, 2008, SK-OV-3, T47-D, and OVCAR-3. This assay is potentially valuable for use in many in vitro systems in which the quantitation of cell density and proliferation is necessary. The practical advantages of AttoPhos assay for measuring endothelial cell numbers include (1) nonradioactivity, (2) simplicity, (3) economy, (4) speed of assessment of proliferation of large number of samples, and (5) amenability to high-throughput drug screening.     

On the dynamic behavior of “NOx-storage/reduction” Pt–Ba/Al2O3 catalyst

The NO_x storage and reduction functions of a Pt–Ba/Al₂O₃ “NO_x storage–reduction” catalyst has been investigated in the present work by applying the transient response and the temperature programmed reaction methods, by using propylene as the reducing agent. It is found that: (i) the storage of NO_x occurs first at BaO and then at BaCO₃, which are the most abundant sites following regeneration of catalyst with propylene; (ii) the overall storage process at BaCO₃ is slower than at BaO; (iii) CO₂ inhibits the NO_x storage at low temperatures; (iv) the amount of NO_x stored up to catalyst saturation at 350 °C corresponds to 17.6% of Ba; (v) the reduction of stored NO_x groups is fast and is limited by the concentration of propylene in the investigated T range (250–400 °C); (vi) selectivity to N₂ is almost complete at 400 °C but is significantly lower at 300 °C due to the formation of NO which can be tentatively ascribed to the presence of unselective Pt–O species.     

The NO x reduction mechanism by H2 under near isothermal conditions over Pt–Ba/Al2O3 Lean NO x Trap systems

The study of the gas-phase NO reduction by H₂ and of the stability/reactivity of NO _x stored over Pt–Ba/Al₂O₃ Lean NO _x Trap systems allowed to propose the occurrence of a reduction process of the stored nitrates occurring via to a Pt-catalyzed surface reaction which does not involve, as a preliminary step, the thermal decomposition of the adsorbed NO _x species.     

Urban Computing and Mobile Devices

In this issue's Works in Progress department, we have 12 urban computing and mobile device entries that span a wide range of computing and social areas. The first entry examines how an urban environment could operate as a large-scale, real-time control system. One project focuses on annotating public spaces and sharing the tags with others. Two projects tie together social networking in cyberspace with local urban communities. Two projects examine computing and social interactions in physical spaces. Two entries explore how to combine synthetic and physical views of urban environments. Four entries investigate how we explore urban spaces, interact with technology in those spaces, and create shared community histories.     

Collaboration in a multi-user game: impacts of an awareness tool on mutual modeling

This paper presents an experimental research that focuses on collaboration in a multi-player game. The aim of the project is to study the cognitive impacts of awareness tools, i.e., artifacts that allow users of a collaborative system to be aware of what is going on in the joint virtual environment. The focus is on finding an effect on performance as well as on the representation an individual builds of what his partner knows, plans and intends to do (i.e., mutual modeling). We find that using awareness tools has a significant effect by improving task performance. However, the players who were provided with this tool did not show any improvement of their mutual modeling. Further analysis on contrasted groups revealed that there was an effect of the awareness tool on mutual modeling for players who spent a large amount of time using the tool.

The Effect of CH<Subscript>4</Subscript> on NH<Subscript>3</Subscript>-SCR Over Metal-Promoted Zeolite Catalysts for Lean-Burn Natural Gas Vehicles

We present a systematic investigation of the deNO_x activity of two commercial metal exchanged zeolite NH₃-SCR catalysts, a Cu-SAPO and a Fe-BEA, in view of their application to the exhaust after-treatment systems of lean-burn natural gas vehicles. The catalytic activity data collected under realistic operating conditions, representative of the after-treatment system of lean-burn vehicles, were compared to those obtained adding methane to the gas feed stream in order to assess the impact of this hydrocarbon, which is usually emitted from natural gas engines, on the NH₃-SCR catalytic chemistry. Our results indicate a negligible impact of methane on the SCR activity at all conditions, but in the presence of a large excess of NO₂ at T?>?400 °C due to methane oxidation by NO₂. The data collected over the two individual metal-promoted zeolites were also compared with those obtained combining both catalysts in sequential arrangements, in order to take advantage of their complementary high activities in different temperature ranges. The Fe-zeolite?+?Cu-zeolite sequence outperformed the two individual components in terms of both overall deNOx efficiency and N₂O selectivity, and was equally insensitive to methane.