Energy Trapping in Dications

The energy interaction curves of a number of diatomic and polyatomic dication systems were calculated in order to study their energy-trapping properties. Generally, the ab initio complete active space multiconfiguration self-consistent field method was used in an extended valence + polarization basis set, with compact effective potentials replacing the core electrons. The diatomic dications include all ten possible binary combinations of oxygen, sulphur, selenium, and tellurium. O₂²⁺ shows the largest exothermicity, measured from equilibrium to the monocation combination asymptote, and highest barrier to dissociation. The calculated equilibrium bond length and harmonic vibrational frequency agree very well with experiment. The O₂²⁺, SO²⁺, SeO²⁺, and TeO²⁺ series show progressively decreasing exothermicities but similar barrier heights. The non-oxides, in contrast, show similar exothermicities but decreasing barriers with increasing size of the atom constituents. These trends are interpreted in terms of both valence bond curve-crossing and molecular orbital bonding models. The ozone dication, O₃²⁺, is found to have a number of low-lying singlet and triplet stationary state structures spanning near-linear to D_3h2+ symmetries. Although the calculated exothermicity is even larger than for O₂²⁺, the barrier to O₂⁺ + O⁺ dissociation is predicted to be low in each case. O₂²⁺ surrounded by six argon atoms to model an isolating environment shows increased equilibrium O–O bond length, decreased exothermicity, and increased barrier to dissociation, relative to the bare dication. O₂²⁺ flanked at each end by a perpendicularly oriented H₂ molecule in a staggered conformation is obstructed from direct conversion to the water dimer dication by a high barrier. However, [(H₂O)₂]²⁺ dissociates smoothly from equilibrium to two water monocations with a large exothermicity but a small barrier.     

β-hydroxyacyl-coa-dehydrogenase (HADH) activity of unfrozen and frozen—thawed frog (Rana esculenta) legs

The β-hydroxyacyl-CoA-dehydrogenase (HADH) activity of unfrozen and thawed frog legs was investigated. The enzyme was extracted by either immersing frog legs in phosphate buffer 0.1 M, pH 6.0 at 25°C for 15 min or pressing them between trichinoscopy glasses. The enzyme activity was assayed using acetoacetyl-CoA as substrate and measured spectrophotometrically at 340 nm. It was possible by both extraction methods to distinguish between thawed and unfrozen samples although when the juice was obtained by pressing the HADH activity of the dilution was ～ 1.5 times higher than that obtained by immersion. The HADH activity was significantly higher (P≤0·001) in frozen-thawed frogs than in unfrozen legs because during freezing there is a release of HADH. No significative differences were found in the HADH activity in samples frozen in the temperature range -10 to -196°C. HADH activity was not affected by the storage time in crushed ice up to 6 days.     

Numerical simulation of the N-dimensional sine-Gordon equation via operational matrices

In this paper, we develop a numerical method for the N-dimensional sine-Gordon equation using differentiation matrices, in the theoretical frame of matrix differential equations.Our method avoids calculating exponential matrices, is very intuitive and easy to express, and can be implemented without toil in any number of spatial dimensions. Although there is currently a vast literature on the numerical treatment of the one-dimensional sine-Gordon equation, the references for the two-dimensional case are much sparser, and virtually nonexistent for higher dimensions.We apply it to a battery of two-dimensional problems taken from the literature, showing that it largely outperforms the previously existing algorithms; while for three-dimensional problems, the results seem very promising.     

Effect of thermoultrasonication on Salmonella enterica serovar Enteritidis in distilled water and intact shell eggs

The combined effects of simultaneous application of ultrasonic waves and heat treatment (thermoultrasonication) on the survival of a strain of Salmonella enterica Enteritidis was studied in both distilled water and intentionally contaminated intact eggs immersed in water. Although minor differences were observed between parameters obtained for thermoultrasonic treatment of bacteria suspended in water and those attached to the shell egg, the thermoultrasonication effects were considered to be of the same level in the range of temperatures assayed (52 to 58 degrees C). This combined process presented a clearly higher killing effect than the heat treatment alone. It decreased the decimal reduction times (D-values) by 80 to 55%, respectively, in the range of temperatures for heat treatment when the organism was suspended in water, which means a 99.5% reduction (5D to >2D) of the original bacterial load versus a 90% reduction for the heat treatment alone. The practical implications of the phenomenon are discussed.     

Changes in selected biochemical and sensory parameters as affected by the superficial inoculation of Penicillium camemberti on dry fermented sausages

An atoxigenic strain of Penicillium camemberti was superficially inoculated on fermented sausages in an attempt to improve their sensory properties. The growth of this mould on the surface of the sausages resulted in an intense proteolysis and lipolysis, which caused an increase in the concentration of free amino acids, free fatty acids (FFA) and volatile compounds. Many of these were derived from amino acid catabolism and were responsible for the "ripened flavour", i.e. branched aldehydes and the corresponding alcohols, acids and esters. The development of the fungal mycelia on the surface of the sausages also protected lipids from oxidation, resulting in both lower 2-thiobarbituric acid (TBARS) values and lipid oxidation-derived compounds, such as aliphatic aldehydes and alcohols. The sensory analysis of superficially inoculated sausages showed clear improvements in odour and flavour and, as a consequence, in the overall quality of the sausages. Therefore, this strain is proposed as a potential starter culture for dry fermented sausage production.     

Can Human Oral Mucosa Stem Cells Differentiate to Corneal Epithelia?

Human oral mucosa stem cells (hOMSCs) arise from the neural crest, they can self-renew, proliferate, and differentiate to several cell lines and could represent a good source for application in tissue engineering. Because of their anatomical location, hOMSCs are easy to isolate, have multilineage differentiation capacity and express embryonic stem cells markers such as—Sox2, Oct3/4 and Nanog. We have used SHEM (supplemented hormonal epithelial medium) media and cultured hOMSCs over human amniotic membrane and determined the cell’s capacity to differentiate to an epithelial-like phenotype and to express corneal specific epithelial markers—CK3, CK12, CK19, Pan-cadherin and E-cadherin. Our results showed that hOMSCs possess the capacity to attach to the amniotic membrane and express CK3, CK19, Pan-Cadherin and E-Cadherin without induction with SHEM media and expressed CK12 or changed the expression pattern of E-Cadherin to a punctual-like feature when treated with SHEM media. The results observed in this study show that hOMSCs possess the potential to differentiate toward epithelial cells. In conclusion, our results revealed that hOMSCs readily express markers for corneal determination and could provide the ophthalmology field with a therapeutic alternative for tissue engineering to achieve corneal replacement when compared with other techniques. Nevertheless, further studies are needed to develop a predictable therapeutic alternative for cornea replacement.     

An integrating factor for nonlinear Dirac equations

This paper presents an efficient integrating-factor method for solving a nonlinear Dirac equation (NLD). Starting with the simplest case of one space-variable, this method, unlike other approaches proposed in the bibliography, can be easily extended to problems with more space-variables. Our algorithm is implemented in Matlab© and the numerical experiments performed reveal its effectiveness and reliability.     

Volatile compound generation in dry fermented sausages by the surface inoculation of selected mould species

The effect of the inoculation of dry fermented sausage surface with an atoxigenic, proteolytic and lipolytic strain of Mucor racemosus, Penicillium aurantiogriseum and Penicillium camemberti on the volatile composition was studied. The analysis of the headspace volatile compounds using gas chromatography/mass spectrometry enabled the identification of 55 volatiles. The study showed that every mould species produced a different volatile profile which was also different from that of the control sausages. Compounds derived from amino acid catabolism, i.e. branched aldehydes and the corresponding alcohols, were produced in higher amounts in sausages inoculated with Penicillium spp. On the other hand, volatiles coming from the microbial esterification were related to sausages inoculated with M. racemosus. The development of the fungal mycelia on the sausage surface protected lipids from oxidation, thus giving rise to fewer lipid oxidation products in the inoculated sausages.     

Online sensor for monitoring a microalgal bioreactor system using support vector regression

In this work, Raman spectroscopy and a machine learning technique known as support vector regression (SVR) are used for building an online sensor to monitor the heterotrophic algal culture conditions in a computer-interfaced bench-scale microalgal bioreactor system, for the production of bio-oil. Monitoring of process conditions in algal cultures is required to enable the use of different control strategies to maximize oil productivity. In order to correlate the Raman spectra with culture conditions, three independent experimental datasets are used. The effect of several preprocessing techniques, including Savitzky-Golay filtering, baseline correction, and standard normal variate transformation, on the goodness of fit is evaluated. A multivariate sensor for real time online monitoring of the concentrations of biomass, glucose and percentage oil content is successfully built and validated. The advantages of using the proposed real-time on-line sensor are illustrated in an experimental microalgal bioreactor system.     

Cross‐Coupling in Flow using Supported Catalysts: Mild,Clean, Efficient and Sustainable Suzuki–Miyaura Coupling in a Single Pass

A mild, clean, practical, sustainable and high yielding procedure for Suzuki–Miyaura cross‐coupling in a single pass using a silica‐supported palladium catalyst is described. The catalyst can be used in more than 30 reactions and for more than 8 h of continuous processing without a decrease in reactivity due to the low leaching observed. Different halides/pseudo‐halides and organoboron compounds can be used without modifying the standard procedure.