Flow modeling and structural characterization in fungal pellets.

Fungal pellets are hierarchical systems that can be found in an ample variety of applications. Modeling transport phenomena in this type of systems is a challenging but necessary task to provide knowledge-based processes that improve the outcome of their biotechnological applications. In this work, an upscaled model for total mass and momentum transport in fungal pellets is implemented and analyzed, using elements of the volume averaging and adjoint homogenization methods departing from the governing equations at the microscale in the intracellular and extracellular phases. The biomass is assumed to be composed of a non-Newtonian fluid and the organelles impervious to momentum transport are modeled as a rigid solid phase. The upscaled equations contain effective-medium coefficients, which are predicted from the solution of adjoint closure problems in a three-dimensional periodic domains representative of the microstructure. The construction of these domains was performed for Laccaria trichodermophora based on observations of actual biological structures. The upscaled model was validated with direct numerical simulations in homogeneous portions of the pellets core. It is shown that no significant differences are observed when the dolipores are open or closed to fluid flow. By comparing the predictions of the average velocity in the extracellular phase resulting from the upscaled model with those from the classical Darcy equation (i.e., assuming that the biomass is a solid phase) the contribution of the intracellular fluid phase was evidenced. This work sets the foundations for further studies dedicated to transport phenomena in this type of systems.

Enzymatic detoxification strategies for neurotoxic insecticides in adults of three tortricid pests.

We examined the role of the most important metabolic enzyme families in the detoxification of neurotoxic insecticides on adult males and females from susceptible populations of Cydia pomonella (L.), Grapholita molesta (Busck), and Lobesia botrana (Denis & Schiffermüller). The interaction between the enzyme families - carboxylesterases (EST), glutathione-S-transferases (GST), and polysubstrate monooxygenases (PSMO) - with the insecticides - chlorpyrifos, λ-cyhalothrin, and thiacloprid - was studied. Insect mortality arising from the insecticides, with the application of enzyme inhibitors - S,S,S-tributyl phosphorotrithioate (DEF), diethyl maleate (DEM), and piperonyl butoxide (PBO) - was first determined. The inhibitors' influence on EST, GST, and PSMO activity was quantified. EST and PSMO (the phase-I enzymatic activities) were involved in the insecticide detoxification in the three species for both sexes, highlighting the role of EST, whereas GST (phase-II enzymes) was involved only in G. molesta insecticide detoxification. L. botrana exhibited, in general, the highest level of enzymatic activity, with a significantly higher EST activity compared with the other species. It was the only species with differences in the response between sexes, with higher GST and PSMO activity in females than in males, which can be explained as the lower susceptibility of the females to the tested insecticides. A positive correlation between PSMO activity and the thiacloprid LD50s in the different species-sex groups was observed explaining the species-specific differences in susceptibility to the product reported in a previous study.

Competition between Polar and Nonpolar Lattice Distortions in Oxide Quantum Wells: New Critical Thickness at Polar Interfaces.

Two basic lattice distortions permeate the structural phase diagram of oxide perovskites: antiferrodistortive (AFD) rotations and tilts of the oxygen octahedral network and polar ferroelectric modes. With some notable exceptions, these two order parameters rarely coexist in a bulk crystal, and understanding their competition is a lively area of active research. Here we demonstrate, by using the LaAlO_{3}/SrTiO_{3} system as a test case, that quantum confinement can be a viable tool to shift the balance between AFD and polar modes and selectively stabilize one of the two phases. By combining scanning transmission electron microscopy (STEM) and first-principles-based models, we find a crossover between a bulklike LaAlO_{3} structure where AFD rotations prevail, to a strongly polar state with no AFD tilts at a thickness of approximately three unit cells; therefore, in addition to the celebrated electronic reconstruction, our work unveils a second critical thickness, related not to the electronic properties but to the structural ones. We discuss the implications of these findings, both for the specifics of the LaAlO_{3}/SrTiO_{3} system and for the general quest towards nanoscale control of material properties.

High-quality III-nitride films on conductive, transparent (2Ì 01)-oriented ß-Ga2O3 using a GaN buffer layer.

We demonstrate the high structural and optical properties of InxGa1-xN epilayers (0 ≤ x ≤ 23) grown on conductive and transparent (01)-oriented ß-Ga2O3 substrates using a low-temperature GaN buffer layer rather than AlN buffer layer, which enhances the quality and stability of the crystals compared to those grown on (100)-oriented ß-Ga2O3. Raman maps show that the 2″ wafer is relaxed and uniform. Transmission electron microscopy (TEM) reveals that the dislocation density reduces considerably (~4.8 × 10(7) cm(-2)) at the grain centers. High-resolution TEM analysis demonstrates that most dislocations emerge at an angle with respect to the c-axis, whereas dislocations of the opposite phase form a loop and annihilate each other. The dislocation behavior is due to irregular (01) ß-Ga2O3 surface at the interface and distorted buffer layer, followed by relaxed GaN epilayer. Photoluminescence results confirm high optical quality and time-resolved spectroscopy shows that the recombination is governed by bound excitons. We find that a low root-mean-square average (≤1.5 nm) of InxGa1-xN epilayers can be achieved with high optical quality of InxGa1-xN epilayers. We reveal that (01)-oriented ß-Ga2O3 substrate has a strong potential for use in large-scale high-quality vertical light emitting device design.

Tetragonal phase of epitaxial room-temperature antiferromagnet CuMnAs.

Recent studies have demonstrated the potential of antiferromagnets as the active component in spintronic devices. This is in contrast to their current passive role as pinning layers in hard disk read heads and magnetic memories. Here we report the epitaxial growth of a new high-temperature antiferromagnetic material, tetragonal CuMnAs, which exhibits excellent crystal quality, chemical order and compatibility with existing semiconductor technologies. We demonstrate its growth on the III-V semiconductors GaAs and GaP, and show that the structure is also lattice matched to Si. Neutron diffraction shows collinear antiferromagnetic order with a high Néel temperature. Combined with our demonstration of room-temperature-exchange coupling in a CuMnAs/Fe bilayer, we conclude that tetragonal CuMnAs films are suitable candidate materials for antiferromagnetic spintronics.

Magnetic nonuniformity and thermal hysteresis of magnetism in a manganite thin film.

We measured the chemical and magnetic depth profiles of a single crystalline (La(1-x)Pr(x))(1-y)Ca(y)MnO(3-δ) (x=0.52±0.05, y=0.23±0.04, δ=0.14±0.10) film grown on a NdGaO(3) substrate using x-ray reflectometry, electron microscopy, electron energy-loss spectroscopy, and polarized neutron reflectometry. Our data indicate that the film exhibits coexistence of different magnetic phases as a function of depth. The magnetic depth profile is correlated with a variation of chemical composition with depth. The thermal hysteresis of ferromagnetic order in the film suggests a first-order ferromagnetic transition at low temperatures.

[Usefulness of IPC continuous monitoring in shunt dysfunction]. / Utilidad de la monitorizacion de la PIC en pacientes con sospecha de disfuncion valvular.

Shunt dysfunction is a common situation in neurosurgery. Often symptoms, physical examination and radiology are not enough to set a diagnosis. ICP continuous monitoring is a safe and reliable tool that provides valuable information about CSF dynamics in these patients. Not only quantitative analysis is needed but also a qualitative one that enables pathological waves identification, because high amplitude B waves are strongly related to shunt dysfunction. In this paper experience about ICP continuous monitoring in patients with shunt dysfunction suspect is presented. Quantitative and qualitative data analysis led to a correct diagnosis, improving all the patients treated according to this criterion. An intraparenchymatous Camino® sensor and neuroPICture software (developed by first author) for data collection and graphic representation were used. Complications related to monitoring were absent and graphics obtained useful for qualitative analysis.

Utilidad de la monitorizacion de la PIC en pacientes con sospecha de disfunción valvular / No disponible

La sospecha de disfunción valvular constituye una situación frecuente en neurocirugía. En numerosas ocasiones ni la clínica, ni la exploración, ni la radiología pueden confirmar o descartar el diagnóstico. La monitorización continua de la PIC es un método seguro y fiable que aporta valiosa información acerca de la situación de la dinámica del LCR en estos pacientes. El sistema de registro debe permitir no sólo el análisis cuantitativo de la PIC sino también morfológico deltrazado, para identificar ondas patológicas (como las B de alta amplitud) relacionadas con situaciones de disfunción valvular. En el presente trabajo se recogela experiencia de monitorización continua de la PIC en pacientes con sospecha de disfunción valvular sincriterios clínicos y radiológicos concluyentes, en los que el análisis morfológico del registro permitió un diagnósticofiable que se tradujo en la mejoría de todos los pacientes tratados conforme a este criterio. El método utilizado fue un sensor intraparenquimatoso Camino®con software de recogida y representación neuroPICture© (desarrollado por el primer autor). Las complicaciones relacionadas con la monitorización fueron nulas y el registro obtenido útil para las objetivos propuestos (AU)

Shunt dysfunction is a common situation in neurosurgery. Often symptoms, physical examination and radiology are not enough to set a diagnosis. ICP continuous monitoring is a safe and reliable tool that provides valuable information about CSF dynamics in these patients. Not only quantitative analysis is needed but also a qualitative one that enables pathological waves identification, because high amplitude B waves are strongly related to shunt dysfunction. In this paper experience about ICP continuous monitoring in patients with shunt dysfunction suspect is presented. Quantitative and qualitative data analysis led to a correctdiagnosis, improving all the patients treated according to this criterion. An intraparenchymatous Camino®sensor and neuroPICture software (developed by firstauthor) for data collection and graphic representation were used. Complications related to monitoring wereabsent and graphics obtained useful for qualitative analysis (AU)

The roles of oxygen and alginate-lyase in determining the molecular weight of alginate produced by Azotobacter vinelandii.

An Azotobacter vinelandii mutant lacking alginate-lyase (SML2) and the wild type (ATCC 9046) were used to discriminate between the roles of the polymerase complex and alginate-lyase in the synthesis of alginate in cultures conducted under controlled dissolved oxygen tension (DOT). To avoid the presence of pre-synthesized alginates, all cultures were inoculated with washed cells. For cultures carried out at 3% DOT using the mutant, a well defined family of alginates of high mean molecular weight (MMW) were obtained (985 kDa). Under 1% and 5% DOT, the mutant produced unique families of alginates with lower MMW (150 and 388 kDa). A similar behavior was observed using the wild type: a production of well defined families of alginates of high MMW at 3% DOT (1,250 kDa) and lower MMW at 1% and 5% DOT (370 and 350 kDa). At the end of the ATCC 9046 fermentations, alginate was depolymerized by the action of lyases. Overall, the evidence indicated that polymerization of alginate is carried out by producing families of polysaccharide in a narrow MMW range, and that it is highly dependent on DOT. The role of alginate-lyase (present in the wild type) is restricted to a post-polymerization step.

Alginate production by an Azotobacter vinelandii mutant unable to produce alginate lyase.

Alginate is an industrially relevant linear copolymer composed of beta-1,4-linked D-mannuronic acid and its C-5 epimer L-guluronic acid. The rheological and gel-forming properties of alginates depend on the molecular weight and the relative content of the two monomers. Alginate produced by Azotobacter vinelandii was shown to be degraded towards the end of the culture, an undesirable situation in terms of potential alginate applications. A gene ( algL) encoding the alginate lyase activity AlgL is present within the alginate biosynthetic gene cluster of A. vinelandii. We constructed strain SML2, an A. vinelandii strain carrying a non-polar mutation within algL. No alginate lyase activity was detected in SML2. Under 3% dissolved oxygen tension, higher values of maximum mean molecular weight alginate were obtained (1240 kDa) with strain SML2, compared to those from the parental strain ATCC 9046 (680 kDa). These data indicate that AlgL activity causes the drop in the molecular weight of alginate produced by A. vinelandii.

Effect of oscillating dissolved oxygen tension on the production of alginate by Azotobacter vinelandii.

The effect of oscillating dissolved oxygen tension (DOT) on the metabolism of an exopolysaccharide-producing bacteria (Azotobacter vinelandii) was investigated, particularly on the mean molecular weight (MMW) of the alginate produced. Sinusoidal DOT oscillations were attained by manipulating the oxygen and nitrogen partial pressures at the inlet of a 1.0 L working volume bioreactor. Periods of 1200, 2400, and 4000 s and average amplitudes between 1.0% and 2.2% DOT, with an oscillation axis fixed at 3% DOT, were tested. A culture carried out at constant 3% DOT was used as comparison. The average wave amplitude had an important effect on the maximum mean molecular weight (MMW(max)) of the alginate produced. The higher the amplitude, the lower the MMW(max). As the average wave amplitudes decreased from 2.2% to 1.0%, the MMW(max) increased from 64 to 240 KDa, respectively. Furthermore, at 3% constant DOT (0.0% of amplitude), a MMW(max) of 350 KDa was obtained. No important effect of the oscillating DOT on kinetics of biomass growth, alginate production, and sucrose consumption was observed, compared with constant DOT. The findings of this study point out that accurate DOT control is crucial if a particular molecular weight species of alginate needs to be produced, particularly in large fermentors, where bacteria are exposed to an oscillatory environment as a result of DOT gradients caused by the high viscosity of the broth and insufficient mixing.

[Ultrasonic measurement of the cerebellum in the newborn infant as a prognostic index of gestational age. (A preliminary study)]. / Medición del cerebelo por ultrasonido en el neonato como índice predictivo de edad gestacional. (Estudio preliminar).

This paper studies if cerebellum measurement by ultrasound is a point of prognostic value for evaluation of gestational age. Ninety-nine neonates of different age of gestation, were studied. Ultrasonographic study of the cerebellum was done in all the cases during the first 24 hours of life. It is suggested that the cerebellum measurement may be one indicator more for the evaluation of gestational age, and therefore of value to identify the products with growth disturbances.

[Peri-intraventricular hemorrhage in pre-term newborns weighing less than 1,000 g., and its possible relationship with way of delivery]. / Hemorragia peri-intraventricular en neonatos de pretérmino con peso inferior a 1,000 g., y su posible relación con la vía de nacimiento.

The Cerebral ultrasonographic study of 20 preterm newborns under 1,000 g. is presented. Two groups were formed: 15 by vaginal via, and 5 by section. There was a higher frequency of cerebral hemorrhage among pre-term newborns by vaginal via than in products obtained through cesarean section. The causes for higher vulnerability to cerebral hemorrhage in the brain of the pre-term products, are mentioned. The changes in conduct for the birth of pre-term products should wait for more experience.

Leucomalacia periventricular en un recien nacido. / Periventricular leuKomalakia in a newborn infant

La leucomalacia periventricular en el recien nacido de pretermino en vida, puede presentarse con manifestaciones clinicas sugestivas de meningitis. Se describe un caso en que los signos neurologicos que describen a la meningitis, tales como: estupor, convulsiones, abombamiento de la fontanela anterior, rigidez de extensores (opistotonos), signos focales cerebrales (desviacion de los ojos), rigidez de nuca, asi como la expresion citoquimica del liquido cefalorraquideo y la cuenta diferencial de globulos blancos en la biometria hematica, se presentaron en un recien nacido de pretermino al que por ultrasonografia del cerebro se le diagnostico leucomalacia periventricular. Los cultivos de liquido cefalorraquideo y frotis para la tincion de Gram no mostraron bacterias asi como tampoco pudieron ser aisladas o detectadas en sangre. Las manifestaciones neurologicas y los hallazgos de laboratorio se correlacionan con la lesion identificada por ultrasonido, durante el curso clinico del padecimiento y se confirmaron con la autopsia descartandose meningitis.La importancia de identificar lesiones de leucomalacia periventricular em vida, permitira evitar especulaciones sobre signos neurologicos que pueden sustentar la impresion clinica de meningitis en cuadros donde no puede aislarse un agente patogeno

Estudio ecocardiografico de la persistencia del conducto arterioso (PCA) en neonatos de pretermino. / Echocardiographic study of the persistence of patent ductus arteriosus in preterm newborn infants

En 107 neonatos de pretermino se midio la relacion auricula izquierda/aorta (AI/AO) por medio de la ecocardiografia modo M. Se comprobo que los recien nacidos de pretermino afectados de persistencia del conducto arterioso (PCA) (42 pacientes) presentaron una relacion AI/AO mayor que la observada en los neonatos sin este padecimiento (57 pacientes). En cinco casos el, estudio ecocardiografico mostro la existencia de PCA antes de la aparicion de los sintomas clinicos. Los neonatos sin PCA presentaron en casi todos los casos una relacion AI/AO inferior a 1,0, mientras que los afectados de PCA tuvieron un valor promedio de la relacion AI/AO mayor de 1,20. En los neonatos de pretermino en los que se analizo la evolucion de la relacion AI/AO luego del tratamiento de la PCA, se observo una estrecha relacion entre el descenso de la relacion AI/AO y la mejoria clinica, aunque los cambios ecocardiograficos precedieron a la desaparicion completa de los signos clinicos de PCA