The Crystal Structure of Nitrosomonas Europaea Sucrose Synthase Reveals Critical Conformational Changes and Insights into the Sucrose Metabolism in Prokaryotes

In this paper we report the first crystal structure of a prokaryotic sucrose synthase from the non-photosynthetic bacterium Nitrosomonas europaea. The obtained structure was in an open form, whereas the only other available structure from the plant Arabidopsis thaliana was in a closed conformation. Comparative structural analysis revealed a “hinge-latch” combination, which is critical to transition between the open and closed forms of the enzyme. The N. europaea sucrose synthase shares the same fold as the GT-B family of the retaining glycosyltransferases. In addition, a triad of conserved homologous catalytic residues in the family showed to be functionally critical in the N. europaea sucrose synthase (Arg567, Lys572, Glu663). This implies that sucrose synthase shares not only a common origin with the GT-B family, but also a similar catalytic mechanism. The enzyme preferred transferring glucose from ADP-glucose rather than UDP-glucose like the eukaryotic counterparts. This predicts that these prokaryotic organisms have a different sucrose metabolic scenario from plants. Nucleotide preference determines where the glucose moiety is targeted after sucrose is degraded

Domain Walls and Metastable Vacua in Hot Orientifold Field Theories

We consider "Orientifold field theories", namely SU(N) gauge theories with Dirac fermions in the two-index representation at high temperature. When N is even these theories exhibit a spontaneously broken Z2 centre symmetry. We study aspects of the domain wall that interpolates between the two vacua of the theory. In particular we calculate its tension to two-loop order. We compare its tension to the corresponding domain wall in a SU(N) gauge theory with adjoint fermions and find an agreement at large-N, as expected from planar equivalence between the two theories. Moreover, we provide a non-perturbative proof for the coincidence of the tensions at large-N. We also discuss the vacuum structure of the theory when the fermion is given a large mass and argue that there exist N-2 metastable vacua. We calculate the lifetime of those vacua in the thin wall approximation.Comment: 29 pages, 4 figures. v2: minor changes in the introduction section. to appear in JHE

Extreme Technicolor & The Walking Critical Temperature

We map the phase diagram of gauge theories of fundamental interactions in the flavor-temperature plane using chiral perturbation theory to estimate the relation between the pion decaying constant and the critical temperature above which chiral symmetry is restored. We then investigate the impact of our results on models of dynamical electroweak symmetry breaking and therefore on the electroweak early universe phase transition.Comment: RevTeX, 18 pages, 3 figure

Development of a healthy biscuit: an alternative approach to biscuit manufacture

OBJECTIVE: Obesity (BMI >30) and related health problems, including coronary heart disease (CHD), is without question a public health concern. The purpose of this study was to modify a traditional biscuit by the addition of vitamin B(6), vitamin B(12), Folic Acid, Vitamin C and Prebiotic fibre, while reducing salt and sugar. DESIGN: Development and commercial manufacture of the functional biscuit was carried out in collaboration with a well known and respected biscuit manufacturer of International reputation. The raw materials traditionally referred to as essential in biscuit manufacture, i.e. sugar and fat, were targeted for removal or reduction. In addition, salt was completely removed from the recipe. PARTICIPANTS: University students of both sexes (n = 25) agreed to act as subjects for the study. Ethical approval for the study was granted by the University ethics committee. The test was conducted as a single blind crossover design, and the modified and traditional biscuits were presented to the subjects under the same experimental conditions in a random fashion. RESULTS: No difference was observed between the original and the modified product for taste and consistency (P > 0.05). The modified biscuit was acceptable to the consumer in terms of eating quality, flavour and colour. Commercial acceptability was therefore established. CONCLUSION: This study has confirmed that traditional high-fat and high-sugar biscuits which are not associated with healthy diets by most consumers can be modified to produce a healthy alternative that can be manufactured under strict commercial conditions

Quartz crystal Microbalance with dissipation monitoring for biomedical applications: Open source and low cost prototype with active temperature control

Advances in sensors have revolutionized the biomedical engineering field, having an extreme affinity for specific analytes also providing an effective, real-time, point-of-care testing for an accurate diagnosis. Quartz Crystal Microbalance (QCM) is a well-established sensor that has been successfully applied in a broad range of applications to monitor and explore various surface interactions, in situ thin-film formations, and layer properties. This technology has gained interest in biomedical applications since novel QCM systems are able to work in liquid media. QCM with dissipation monitoring (QCM-D) is an expanded version of a QCM that measures changes in damping properties of adsorbed layers thus providing information on its viscoelastic nature. In this article, an open source and low cost QCM-D prototype for biomedical applications was developed. In addition, the system was validated using different Polyethylene Glycol (PEG) concentrations due to its importance for many medical applications. The statistics show a bigger dissipation of the system as the fluid becomes more viscous, also having a very acceptable sensibility when temperature is controlled