Servicio de Control Microbiológico (SCM), como Estrategia Didáctica para el laboratorio de Tecnología de Alimentos [Microbiological Control Service, as Didactic Strategy for Food Technology Lab]

Servicio de Control Microbiológico (SCM) es una Estrategia Didáctica dirigida a alumnos de Laboratorios de: Tecnología de Alimentos (LABTEC) y Microbiología de Alimentos (LMA), en la Facultad de Química (FQ) de la Universidad Nacional Autónoma de México (UNAM). Se basa en el desempeño de roles profesionales, donde alumnos de LABTEC que elaboran alimentos actúan como productores que requieren análisis microbiológicos; los alumnos de LMA actúan como proveedores del servicio de control microbiológico. Se elaboran solicitudes y reportes formales, basados en normas de referencia, para que se pueda concluir sobre la calidad higiénica del alimento. La estrategia ha permitido a los participantes, una experiencia muy cercana al ejercicio profesional, para evaluar buenas prácticas de manufactura, trabajo individual y en equipo. Todos desarrollaron habilidades de comunicación profesional, solución de problemas y conciencia sobre la importancia de la calidad higiénica de los alimentos. El control microbiológico en LABTEC se ha realizado sin recursos adicionales, pues se aplican aquellos destinados a las prácticas de LMA. Además de la experiencia de aprendizaje, se está generando mejora continua en ambas asignaturas. [Microbiological control service (SCM) as a didactic strategy is aimed to those students in laboratories of food technology (LABTEC) and food microbiology (LMA), at the Universidad Nacional Autónoma de México’s School of Chemistry (FQ). It is based in professional role playing; LABTEC students elaborate the products and act as food producers in need of microbiological analysis; LMA students perform as service providers, for microbiological control. They elaborate formal requests and microbiological analysis report, based on mandatory standards, which can lead to conclusions about product’s hygienic quality. The strategy has given students an experience close to professional practice, to evaluate good manufacturing practices, individual and team work. All developed professional communication skills, problems identification and proposals for solving them, as well as consciousness about the importance of hygienic quality of food. The microbiological control in LABTEC has been carried out without the need for additional resources, since those intended for LMA practices are applied to these real samples. The experience is generating continuous improvement in both courses.

Efficacy of aldose reductase inhibitors is affected by oxidative stress induced under X-ray irradiation

Human aldose reductase (hAR, AKR1B1) has been explored as drug target since the 1980s for its implication in diabetic complications. An activated form of hAR was found in cells from diabetic patients, showing a reduced sensitivity to inhibitors in clinical trials, which may prevent its pharmacological use. Here we report the conversion of native hAR to its activated form by X-ray irradiation simulating oxidative stress conditions. Upon irradiation, the enzyme activity increases moderately and the potency of several hAR inhibitors decay before global protein radiation damage appears. The catalytic behavior of activated hAR is also reproduced as the KM increases dramatically while the kcat is not much affected. Consistently, the catalytic tetrad is not showing any modification. The only catalytically-relevant structural difference observed is the conversion of residue Cys298 to serine and alanine. A mechanism involving electron capture is suggested for the hAR activation. We propose that hAR inhibitors should not be designed against the native protein but against the activated form as obtained from X-ray irradiation. Furthermore, since the reactive species produced under irradiation conditions are the same as those produced under oxidative stress, the described irradiation method can be applied to other relevant proteins under oxidative stress environments.This work was started, and partly supported by a grant from the Spanish Nuclear Council (CSN)

New families of symplectic splitting methods for numerical integration in dynamical astronomy

We present new splitting methods designed for the numerical integration of near-integrable Hamiltonian systems, and in particular for planetary N-body problems, when one is interested in very accurate results over a large time span. We derive in a systematic way an independent set of necessary and sufficient conditions to be satisfied by the coefficients of splitting methods to achieve a prescribed order of accuracy. Splitting methods satisfying such (generalized) order conditions are appropriate in particular for the numerical simulation of the Solar System described in Jacobi coordinates. We show that, when using Poincar\'e Heliocentric coordinates, the same order of accuracy may be obtained by imposing an additional polynomial equation on the coefficients of the splitting method. We construct several splitting methods appropriate for each of the two sets of coordinates by solving the corresponding systems of polynomial equations and finding the optimal solutions. The experiments reported here indicate that the efficiency of our new schemes is clearly superior to previous integrators when high accuracy is required.Comment: 24 pages, 2 figures. Revised version, accepted for publication in Applied Numerical Mathematic

Fluid gels: a new feedstock for high viscosity jetting

Suspensions of gel particles which are pourable or spoonable at room temperature can be created by shearing a gelling biopolymer through its gelation (thermal or ion mediated) rather than allowing quiescent cooling – thus the term ‘fluid gel’ may be used to describe the resulting material. As agar gelation is thermoreversible this type of fluid gel is able to be heated again to melt agar gel particles to varying degrees then re-form a network quiescently upon cooling, whose strength depends on the temperature of re-heating, determining the amount of agar solubilised and subsequently able to partake in re-gelation. Using this principle, for the first time fluid gels have been applied to a high viscosity 3D printing process wherein the printing temperature (at the nozzle) is controllable. This allows the use of ambient temperature feedstocks and by altering the nozzle temperature, the internal nature (presence or absence of gel particles) and gel strength of printed droplets differs. If the nozzle prints at different temperatures for each layer a structure with modulated texture could be created

Natural and sail-displaced doubly-symmetric Lagrange point orbits for polar coverage

This paper proposes the use of doubly-symmetric, eight-shaped orbits in the circular restricted three-body problem for continuous coverage of the high-latitude regions of the Earth. These orbits, for a range of amplitudes, spend a large fraction of their period above either pole of the Earth. It is shown that they complement Sun-synchronous polar and highly eccentric Molniya orbits, and present a possible alternative to low thrust pole-sitter orbits. Both natural and solar-sail displaced orbits are considered. Continuation methods are described and used to generate families of these orbits. Starting from ballistic orbits, other families are created either by increasing the sail lightness number, varying the period or changing the sail attitude. Some representative orbits are then chosen to demonstrate the visibility of high-latitude regions throughout the year. A stability analysis is also performed, revealing that the orbits are unstable: it is found that for particular orbits, a solar sail can reduce their instability. A preliminary design of a linear quadratic regulator is presented as a solution to stabilize the system by using the solar sail only. Finally, invariant manifolds are exploited to identify orbits that present the opportunity of a ballistic transfer directly from low Earth orbit

El clima vitícola de las regiones productoras de uvas para vinos en Cuba.

El clima de Cuba se ha definido como tropical, estacionalmente húmedo, con influencia marítima y rasgos de semicontinentalidad (Köpen, 1907; Iñiguez y Mateo, 1980; Lima et al., 1988; Lecha et al., 1993). De acuerdo con Lima (1992) es tropical modificado por diferentes factores: la configuración alargada del Archipiélago cubano que hace mas efectiva la acción de los vientos alisios del nordeste y la acción reguladora del mar sobre las temperaturas de la costa norte, las corrientes marítimas cálidas que lo bañan, la acción permanente del anticiclón del Atlántico Norte, la proximidad al continente americano y los vientos nortes y sures, entre otros

The turtles from the upper Eocene, Osona County (Ebro Basin, Catalonia, Spain): new material and its faunistic and environmental context

Eochelone voltregana n. sp. is a new marine cryptodiran cheloniid found at the Priabonian levels (latest Eocene) of the Vespella marls member of the Vic–Manlleu marls formation. It is the second cheloniid from Santa Cecília de Voltregà (Osona County, Spain), the first one being Osonachelus decorata from the same formation. Shell parameters indicate that the new species belongs to a branch of sea turtles including the Eocene Anglo–Franco–Belgian forms Argillochelys, Puppigerus and Eochelone (the shell of the latter was studied here for the first time) as well as Glarichelys from the Oligocene of Switzerland, all of them predating the worldwide living Miocene genera. The description of two other more littoral–continental Eocene species is given: Trionyx sp., from an older layer of the same formation; and the podocnemidid erymnochelyine, Cordichelys from a more basal layer of a middle Eocene (Lutetian) formation. The last one is identified as the only evidence of the Shweboemys subgroup in the European record, being distinct from the other known Osona County pleurodire Eocenochelus farresi, which is a member of the Erymnochelys group (same subfamily), from the younger Priabonian Sant Martí Xic layer. Thus, an update on the marine turtle fauna of the eastern Ebro Basin that variably opened in the east during Eocene times is provided. The turtles of Osona County belong to two suborders and five genera with three new species and extend the known distribution of their families (LSID urn:lsid:zoobank.org:act:48CE8676-7B82-4EF2-8165-27BEE90129F2).</p