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An artificial photosynthetic reaction center consisting of a carotenoid (C), a dimesitylporphyrin (P), and a bis(heptafluoropropyl)porphyrin (P(F)), C-P-P(F) , and the related triad in which the central porphyrin has been metalated to give C-P(Zn)-P(F) have been synthesized and characterized by transient spectroscopy. These triads are models for amphipathic triads having a carboxylate group attached to the P(F) moiety; they are designed to carry out redox processes across lipid bilayers. Triad C-P-P(F) undergoes rapid singlet-singlet energy transfer between the porphyrin moieties, so that their excited states are in equilibrium. In benzonitrile, photoinduced electron transfer from the first excited singlet state of P and hole transfer from the first excited singlet state of P(F) yield the initial charge-separated state C-P(.) (+)-P(F) (.) (-). Subsequent hole transfer to the carotenoid moiety generates the final charge-separated state C(.) (+)-P-P(F) (.) (-), which has a lifetime of 1.1 mus and is formed with a quantum yield of 0.24. In triad C-P(Zn)-P(F) energy transfer from the P(Zn) excited singlet to the P(F) moiety yields C-P(Zn)-(1)P(F) . A series of electron-transfer reactions analogous to those observed in C-P-P(F) generates C(.) (+)-P(Zn)-P(F) (.) (-), which has a lifetime of 750 ns and is formed with a quantum yield of 0.25. Flash photolysis experiments in liposomes containing an amphipathic version of C-P(Zn)-P(F) demonstrate that the added driving force for photoinduced electron transfer in the metalated triad is useful for promoting electron transfer in the low-dielectric environment of artificial biological membranes. In argon-saturated toluene solutions of C-P-P(F) and C-P(Zn)-P(F) , charge separation is not observed and a considerable yield of triplet species is generated upon excitation of the porphyrin moieties. In both triads triplet energy localized in the P(F) moiety is channeled to the carotenoid chromophore by a triplet energy-transfer relay mechanism. Certain photophysical characteristics of these triads, including the sequential electron transfer and the triplet energy-transfer relay mechanism, are reminiscent of those observed in natural reaction centers of photosynthetic bacteria.

In this research, the extraction of egg-yolk lecithin with ethanol was studied. Extraction was performed with deoiled and undeoiled yolks and with heated and unheated yolks. The yield of the extracted fraction relative to the initial material, phospholipid (PL) purity, and cholesterol content of both the PC-enriched fractions and the remaining PL fractions were determined. The yield and PL purity of the PC-enriched fractions obtained from the undeoiled yolks were 23.9 and 35.7%, and those obtained from deoiled yolks were 13.5 and 53.3%. The recovery of total PL in the two fractions was higher from the undeoiled (70%) than from the deoiled yolks (60%). However, heating had a negligible effect on PL extraction. Better enrichment of PC was observed by extraction from the undeoiled than from the deoiled yolks. The cholesterol content of the PC-enriched fraction obtained from the undeoiled yolks was much higher than that from the deoiled yolks.

Egg-yolk lecithin has phospholipid (PL) classes and a FA composition that differ from soybean lecithin and may have unique functional properties. The purposes of this research were to develop an effective method for extracting a sufficient amount to lecithin from fresh egg yolks and to evaluate its functional properties. Ethanol was used to dehydrate and partially extract the PL, after which hexane was used to extract the total lipids. A phase separation of the combined extracts resulted in neutral and polar lipid fractions. An acetone precipitation of PL from the final polar lipid fraction was necessary to remove the residual neutral lipids, especially cholesterol. The purity of PL in the lecithin product was 95%. Surface tension reduction, emulsion stability, and oxidative stability studies were conducted to characterize the functional properties of egg-yolk lecithin. Egg-yolk lecithin and soy lecithin had similar surface activities, as evaluated by the surface tension reduction in an aqueous system and the critical micelle concentration. Soybean lecithin created a more stable emulsion than egg-yolk lecithin. However, egg-yolk lecithin was more oxidatively stable than soybean lecithin.

In the present paper, an exergetic analysis of a double stage thermal compressor using the lithium bromide–water solution is performed. The double stage system considered allows obtaining evaporation temperatures equal to 5 °C using solar heat coming from flat plate collectors and other low grade thermal sources. In this study, ambient air and water are alternatively used as cooling fluids without crystallization problems up to condensation–absorption temperatures equal to 50 °C. The results obtained give the entropy generated, the exergy destroyed and the exergetic efficiency of the double stage thermal compressor as a function of the absorption temperature. The conclusions obtained show that the irreversibilities generated by the double stage thermal compressor will tend to increase with the absorption temperature up to 45 °C. The maximum value corresponds to 1.35 kJ kg−1 K−1. The entropy generated and the exergy destroyed by the air cooled system are higher than those by the water cooled one. The difference between the values increases when the absorption temperature increases. For an absorption temperature equal to 50 °C, the air cooled mode generates 14% more entropy and destroys 14% more exergy than the water cooled one. Also, the results are compared with those of previous studies for single and double effect air cooled and water cooled thermal compressors. The conclusions show that the double stage system has about 22% less exergetic efficiency than the single effect one and 32% less exergetic efficiency than the double effect one.

Photonic crystals can be viewed just as a subclass of a larger family of material systems called metamaterials in which the properties largely derive from the structure rather than from the material itself. Opals have only a relatively recent history as photonic bandgap materials and have received a strong thrust from their adequacy as scaffoldings for further templating other materials with photonic applications for instance. The tortuous route from materials to devices might perhaps find reward in the ease and low cost of fabrication of these materials. In this paper we present a review of recent work and work under way in our laboratory tending towards synthesis based on self-assembly to realize metamaterials in the optical range. This comprises the formation of the templates (opals) and subsequent synthesis of guest materials such as semiconductors, metals and insulators. The possibility of further processing allows additional two-dimensional and quasi-two-dimensional patterning for the design of new structures. In this paper we show how the raw matter can be checked for quality and learn how to use its optical properties to evaluate application potential. Issues relating to the optical properties (such as crystalline quality, finite size effects and infiltration with other materials) are examined. We show some examples where opals are used to pattern the growth of other materials with photonic applications (such as metals and semiconductors) and developments leading to both vertical and lateral engineering are shown.

Artificial photosynthetic antenna systems have been synthesized based on carotenoid polyenes and polymer-polyenes covalently attached to tetrapyrroles. Absorption of light in the blue/green region of the spectra excites the polyenes to their S2 state, and ultrafast singlet energy transfer to the tetrapyrroles occurs when the chromophores are in partial conjugation. The additional participation of other excited states of the polyene in the energy-transfer process is a requirement for perfect antenna function. Analogs of photosynthetic reaction centers consisting of tetrapyrrole chromophores covalently linked to electron acceptors and donors have been prepared. Excitation of these constructs results in a cascade of energy transfer/electron transfer which, in selected cases, forms a final charge-separated state characterized by a giant dipole moment (>150 D), a quantum yield approaching unity, a significant fraction of the photon energy stored as chemical potential, and a lifetime sufficient for reaction with secondary electron donors and acceptors. A new antenna-reaction center complex is described in which a carotenoid moiety is located in partial conjugation with the tetrapyrrole π-system allowing fast energy transfer (

In this paper, we propose a new approach to stability analysis of Takagi-Sugeno fuzzy system with control saturation. The analysis of the nonlinear closed-loop system is studied through a quadratic approach. In this context, the conditions guarantee the global stability of the saturated Takagi-Sugeno fuzzy system are stated. These sufficient conditions are formulated in terms of Linear Matrix Inequalities (LMI).

The detection of clouds and the analysis of cloud frequency play an important role for operational weather prediction as well as for climate-ecological studies. A threshold technique for cloud detection in the tropical mountainous area of Ecuador is presented which is based on National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer (NOAA-AVHRR) data. Cloud classification is performed for both day and night overpasses by applying several threshold tests which also include ancillary terrain information. From a set of 155 images, maps of relative cloud frequency are calculated for Ecuador and adjacent areas as well as the central study area of an ecological project in southern Ecuador (Loja). Results show a clear relation between topography, main airflow and cloudiness due to barrage and lee-effects. The spatial extension of high mountain ecosystems such as the Ecuadorian Paramo has been proven to be significantly influenced by the spatial pattern of cloud frequency.

International audience; During the 1999/2000 agricultural seasons, an experiment was carried out on winter wheat fields in the semiarid Yaqui Valley (Northwest Mexico). This data set was used to calibrate the evolution of the leaf area index (LAI) simulated by STICS, which was found to be in excellent agreement with estimates obtained from field reflectance measurements. After calibration, STICS was able to simulate satisfactorily the seasonal levels and trends observed in net radiation, soil moisture and evapotranspiration, but the crop temperature was overestimated by about 2.5 °C. On a larger scale, STICS was run on 16 fields with contrasting management practices. The simulations indicate that yield predictability is significantly lower for later sowing dates, consistent with observations. The seasonal variations of field and satellite data (Landsat-ETM+, Terra-MODIS and VEGETATION) NDVI were very close. However, some difficulties were noted: saturation of NDVI at high LAI values and smoothed variability on a 1-km spatial scale, as well as the need for a sound methodology for processing satellite data.

A triad consisting of a carotenoid (C), a dimesitylporphyrin (P), and a tris(heptafluoropropyl)porphyrin (PF), C−P−PF, has been synthesized and found to undergo rapid singlet−singlet energy transfer between the porphyrin moieties so that their excited states are in equilibrium. Photoinduced electron transfer from the first excited singlet state of P, or hole transfer from the first excited singlet state of PF, yields C−P•+−PF•-. Electron transfer from C then yields the final charge-separated state C•+−P−PF•- with a quantum yield of 0.73 and a lifetime of 500 ns in tetrahydrofuran solution at ambient temperature. The final charge-separated state decays to form primarily a triplet excited state localized on the carotenoid, 3C−P−PF, rather than the ground state. A second triad in which P is metalated (PZn) has also been synthesized. In this system, the excited singlet states of the porphyrins are no longer in equilibrium; fast electron transfer from excited PZn to PF to form C−PZn•+−PF•- and also fast energy...

Artificial light-harvesting constructs were synthesized by covalently linking two carotenoids to the central silicon atom of a phthalocyanine (Pc) derivative. Triad 1 binds two carotenoids having nine conjugated double bonds, whereas triad 2 binds two carotenoids having 10 carbon−carbon double bonds in conjugation. Fluorescence excitation experiments indicated that, in triad 1 dissolved in n-hexane, the carotenoid to Pc singlet energy transfer efficiency is ca. 92%, whereas in triad 2, it is 30%. Results from ultrafast laser spectroscopy indicate that upon population of the optically allowed S2 state of the carotenoid the optically forbidden states S1 and S* are rapidly generated in both triad 1 and triad 2. In triad 1, S2, S1, and S* all contribute singlet electronic energy to Pc. In triad 2, singlet electronic energy transfer to Pc occurs primarily from the optically allowed S2 state with little energy transfer to Pc via the S1 state, and there is no evidence for energy transfer via S*. Instead, in tria...

In order to evaluate the association of influenza viruses with hospitalizations for acute respiratory infection in infants younger than two years old during epidemics of respiratory syncytial virus infection, we studied 512 nasal washes from this population. The samples were obtained from 1997 to 2000. A total of 337 viruses were isolated: 264 respiratory syncytial viruses, 62 influenza viruses, eight parainfluenza viruses, two adenovirus and one rhinovirus. Hospitalizations for acute respiratory infection were owing to influenza and respiratory syncytial viruses in 18.3% vs. 78.3% of all cases, and 32.5% vs. 65.8%, respectively, in the group of infants between 6 months and 2 years old.

Direct current measurements reveal that the circulation of the northern Gulf of California in the annual timescale consists of a cyclonic basinwide gyre (∼0.35 m s−1) that lasts from June to September (4 months), and an anticyclonic gyre (∼0.35 m s−1) lasting from November to April (6 months). The transitions between regimes take about three weeks each. The hypothesis that the difference in duration of the two circulation regimes is due to the seasonal variation of stratification of the water column is explored by simulations with a nonlinear two-layer numerical model of circulation and thermodynamics that includes vertical mixing, parameterized as an entrainment velocity. The model results agree remarkably well with the observations, considering its simplified vertical structure. In addition, the model predicts a net circulation consisting of an anticyclonic gyre of ∼0.05 m s−1, with a corresponding average concavity of the interface, and a two-layer exchange through the main channels of the arc...

N-Dimethyl-N-[2-(N,N-dimethylamino)ethyl]-N-(1-methylnaphthyl)ammonium tetrafluoroborate (I) was synthesized with the aim of obtaining a versatile photoinitiator for vinyl polymerization in organic solvents and water. Salt I was able to trigger the polymerization of acrylamide, 2-hydroxyethylmethacrylate and styrene even at very low concentrations of the salt (∼1.0 × 10 -5 M). Using laser flash photolysis and fluorescence techniques and analyzing the photoproduct distribution, we were able to postulate a mechanism for the photodecomposition of the salt. With irradiation, I undergoes an intramolecular electron-transfer reaction to form a radical ion pair (RIP). The RIP intermediate decomposes into free radicals. The RIP and the free radicals are active species for initiating the polymerization. Depending on the concentration of the vinyl monomers studied, the initiation mechanism of the polymerization reaction changes. At large monomer concentrations, the RIP state is postulated to trigger the reaction by generating the anion radical of the olefin substrate. At a low monomer concentration, the free radicals produced by the decomposition of I are believed to start the chain reaction.

An improved description of the seasonal variability of the geostrophic circulation in the northern Gulf of California is obtained from a historical hydrographic database larger than in previous studies. The evolution of the geostrophic circulation consists of: a cyclonic (summer) period, an anticyclonic (winter) period and two transition periods. The cyclonic (summer) period lasts from June to September (four months) and is characterized by a strongly baroclinic cyclonic gyre which dominates the circulation. The anticyclonic (winter) period starts in November and persists until April (six months); the anticyclonic geostrophic circulation is less robust than that in summer. The transition periods take of the order of one month, occurring around October and April–May, and are characterized by the simultaneous presence of both types of gyres. Empirical Orthogonal Function analysis shows a strong seasonal signal in the dynamic height for the first mode (97·2% of the total variance), whose spatial structure is a closed gyre, which oscillates between cyclonic during the summer months and anticyclonic the rest of the year. The results strengthen and extend those from previous work based on analysis of hydrographic data, on limited direct observations, on satellite image analysis, and on numerical modelling.

Conjugated polymer nanoparticles are widely used in fluorescent labeling and sensing, as they have mean radii between 5 and 100 nm, narrow size dispersion, high brightness, and are photochemically stable, allowing single particle detection with high spatial and temporal resolution. Highly crosslinked polymers formed by linking individual chains through covalent bonds yield high-strength rigid materials capable of withstanding dissolution by organic solvents. Hence, the combination of crosslinked polymers and conjugated polymers in a nanoparticulated material presents the possibility of interesting applications that require the combined properties of constituent polymers and nanosized dimension. In the present work, F8BT@pEGDMA nanoparticles composed of poly (ethylene glycol dimethacrylate)(pEGDMA; a crosslinked polymer) and containing the commercial conjugated polymer poly(9,9-dioctylfluorene-alt-benzothiadiazole)(F8BT) were synthesized and characterized. Microemulsion polymerization was applied to produce F8BT@pEDGMA particles with nanosized dimensions in a ∼25% yield. Photophysical and size distribution properties of F8BT@pEDGMA nanoparticles were evaluated by various methods, in particular single particle fluorescence microscopy techniques. The results demonstrate that the crosslinking/polymerization process imparts structural rigidity to the F8BT@pEDGMA particles by providing resistance against dissolution/disintegration in organic solvents. The synthesized fluorescent crosslinked nanoparticles contain (for the most part) single F8BT chains and can be detected at the single particle level, using fluorescence microscopy, which bodes well for their potential application as molecularly imprinted polymer fluorescent nanosensors with high spatial and temporal resolution. Fil: Ponzio, Rodrigo Andrés. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina Fil: Marcato, Yesica L.. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina Fil: Gomez, María Lorena. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina Fil: Waiman, Carolina Vanesa. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina Fil: Chesta, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina Fil: Palacios, Rodrigo Emiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina

Recently, the use of different types of natural fibers to produce paper and textiles from agave plants has been proposed. Agave atrovirens can be a good source of cellulose and lignin; nevertheless, the microstructural changes that happen during delignification have scarcely been studied. The aim of this work was to study the microstructural changes that occur during the delignification of agave fibers by means of microscopy techniques and image analysis. The fibers of A. atrovirens were obtained from leaves using convective drying, milling, and sieving. Fibers were processed using the Acetosolv pulping method at different concentrations of acetic acid; increasing acid concentration promoted higher levels of delignification, structural damage, and the breakdown of fiber clumps. Delignification followed by spectrometric analysis and microstructural studies were carried out by light, confocal laser scanning and scanning electron microscopy and showed that the delignification process follows three stages: initial, bulk, and residual. Microscopy techniques and image analysis were efficient tools for microstructural characterization during delignification of agave fibers, allowing quantitative evaluation of the process and the development of linear prediction models. The data obtained integrated numerical and microstructural information that could be valuable for the study of pulping of lignocellulosic materials.

A Pressure Bed Sensor (PBS) can offer an unobtrusive method for sleep monitoring. This study focuses on the detection of the sleep related breathing disorders using a PBS in comparison to the methods used in a sleep laboratory. A newly developed PCA modeling approach for the eight sensor signals of the PBS is evaluated using the Reduced Respiratory Amplitude Index (RRAI) as a central measure. The method computes the respiration amplitude with the Hilbert transform, and then detects the events based on a 20% amplitude reduction from the baseline signal. A similar calculation was used for the sleep laboratory RIP measurements, and both PBS and RIP were compared against the reference based on the nasal flow signal. In the reference RRAI method, the respiratory-disordered events were obtained using RemLogic respiration analyzer to detect over 50% amplitude reduction in the nasal respiratory flow, but removing the RemLogic standard hypopnea event associations on the oxygen desaturation events and the sleep arousals. The movement artifacts were automatically detected based on the movement activity signal of the PBS. Twenty-five (25) out of 28 patients were finally analysed. On average 87% of a night measurement has been covered by the system. The correlation coefficient was 0.92 between the PBS and the reference RRAI, and the performance of the PBS was similar with the RIP belts. Classifying the severity of the sleep related breathing by dividing RRAI in groups according to the severity criteria, the sensitivity was 92% and the specificity was 70% for the PBS. The results suggest that PBS recording can provide an easy and un-obstructive alternative method for the detection of the sleep disordered breathing and thus has a great promise for the home monitoring.

The photosensitization effect of three perylene dye derivatives on titanium dioxide nanoparticles (TiO2 NPs) has been investigated. The dyes used, 1,7-dibromoperylene-3,4,9,10-tetracarboxy dianhydride (1), 1,7-dipyrrolidinylperylene-3,4,9,10-tetracarboxy dianhydride (2) and 1,7-bis(4-tert-butylphenyloxy)perylene-3,4,9,10-tetracarboxy dianhydride (3) have in common bisanhydride groups that convert into TiO2 binding groups upon hydrolysis. The different substituents on the bay position of the dyes enable tuning of their redox properties to yield significantly different driving forces for photoinduced electron transfer (PeT). Recently developed TiO2 NPs having a small average size and a narrow distribution (4 ± 1 nm) are used in this work to prepare the dye-TiO2 systems under study. Whereas successful sensitization was obtained with 1 and 2 as evidenced by steady-state spectral shifts and transient absorption results, no evidence for the attachment of 3 to TiO2 was observed. The comparison of the rates of PeT (kPeT) for 1- and 2-TiO2 systems studied in this work with those obtained for previously reported analogous systems, having TiO2 NPs covered by a surfactant layer (Hernandez et al. [2012] J. Phys. Chem. B., 117, 4568–4581), indicates that kPeT for the former systems is slower than that for the later. These results are interpreted in terms of the different energy values of the conduction band edge in each system. Fil: Llansola Portolés, Manuel Jose. Arizona State University; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Bergkamp, Jesse J.. Arizona State University; Estados Unidos Fil: Tomlin, John. Arizona State University; Estados Unidos Fil: Moore, Thomas A.. Arizona State University; Estados Unidos Fil: Kodis, Gerdenis. Arizona State University; Estados Unidos Fil: Moore, Ana L.. Arizona State University; Estados Unidos Fil: Cosa, Gonzalo. McGill University; Canadá Fil: Palacios, Rodrigo Emiliano. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

"A review of state the art about the structure, classification and operation of biosensors applied in food and biological areas is presented. This review is focused to mechanical biosensors that use mili, micro and nanocantilevers. Basic concepts of atomic Ingeniería de optical systems, used as testing platform of biosensors are described. The most funcionalized strategies and force microscopy and procesos / Process engineering geometrical Localización de una planta industrial: Revisión crítica for adecuaciónthe performance in static and dynamic mode 271 configurations are also explained. Mathematical methods y evaluating de los criterios empleados en of the mechanical biosensors are reviewed and examples of application in biological and food areas are provided. An overall esta decisión description of the operational effect of operation conditions and design variables on the sensitivity devices is also proposed. A brief description ofsite selection: Criticaland manufacturing of cantileversused insilicon technology as well as information about (Plant the design processes review and adequation criteria based this decision) BioMEMS and BioNEMS are provided. Finally, overall trends in research, development and commercialization of biosensors J.R. Medina, R.L. probable G.A. of development in food biosensors. Thereby, this review provides an overall view are described briefly as well asRomero y areas Pérez of biosensors, as an exploratory guide to identify the most important aspects of this technology."

"The aim of tbis study was tbe detection of active L. plantarum 299v (probiotic rnicroorganism) growth using rnicrocantilever based biosensors in air and in dynarnic mode by atomic force microscopy. Cornrnercial cantilevers were cleaned witb Piranha solution in order to eliminate contaminants and were functionalized witb silylating solution; afterwards tbe cantilevers were coated by an agarose layer using tbe capillaries technique. An atomic force microscope in tapping mode was required to evaluate tbe resonance frequency shift of cornrnercial cantilevers inoculated with L. plantarum 299v. Humidity and temperature were controlled inside an atmospheric hood during tbe biodetection. The resonance frequency curves were seen to be narrower witb higher Q factor values (~219). The results showed tbat tbe resonance frequency shifted by approximately 5.2±0.8 kHz on tbe inoculated cantilevers tbroughout the growtb kinetics. From the resonance frequency curves and known mechanical properties of tbe cantilevers, tbe biosensor sensitivity was determined to be 383±3 pglHz and tbe biosensor can detect ~400 bacteria. In addition, L. plantarum growtb on tbe cantilever's surface was confirmed by scanning electron microscopy. The results showed tbat it is JXlssible to construct a microbiosensor by using cornmercial cantilevers and atomic force microscopy. These sensors can be used as a platform for tbe detection ofmicroorganisms associated witb functional foods."

X-ray diffraction and differential scanning calorimetry experiments have made it evident that undergoes a first-order structural phase transition at from a -type structure at room temperature to a monoclinic cell at low temperatures. The transition arises from coupled tilts and around [110] and [001] directions of the tetragonal unit cell and have been explained in the framework of the Landau theory using an expansion of the free energy with two interacting order parameters and , taking into account up to sixth-order terms. The large entropy content of the transition has been explained assuming that the ammonium ion is free to rotate around the fourfold crystallographic axis in the high-temperature phase.

The crystal structure of Nd2Fe14B has been analysed at 20 and 290 K by using the four-circle X-ray diffraction technique. The room temperature tetragonal structure (space groupP42tmum) has been accurately determined. At low temperature, the monoclinic distortion (space groupCm) proposed from a recent neutron diffraction experiment has been fully confirmed.

Autologous tumor cell vaccines rely on the concept of preserving an individual's own tumorigenic makeup, expressing its unique set of tumor-associated antigens as well as antigenic elements from the surrounding stroma. These autologous tumor characteristics are usually presented with an immune adjuvant in the hopes of enhancing an immune response.The autologous vaccine we used was composed of tumor cells combined with BCG and formalin. Animal safety and toxicity were evaluated using mice tumors for the immunotherapy. A small number of patients with advanced stage breast cancer were recruited for an uncontrolled study, using the vaccine solely or combined with chemotherapy/radiotherapy.The immunotherapy had shown to be safe in mice and humans. Upon a 5-year follow-up, the survival rate was 60 % for the combined treatment.The data suggest that the combined treatment could be a feasible and safe therapeutic strategy. However, further controlled studies should be conducted.

SETTING: Multidrug-resistant tuberculosis (MDR-TB) and the human immunodeficiency virus (HIV) pose two of the greatest threats to global tuberculosis (TB) control. Given expanding global access to antiretroviral therapy (ART) and second-line TB drugs more data are needed on experiences treating MDR-TB and HIV co-infection in resource-poor settings. OBJECTIVE: To describe the clinical characteristics management outcomes and factors associated with survival among HIV-positive individuals receiving treatment for MDR-TB. DESIGN: This was a retrospective case series of 52 HIV-positive individuals receiving treatment for MDR-TB in Lima Peru. We used Cox proportional hazards regression models to identify risk factors for mortality. RESULTS: A total of 31 (57%) of the cohort died on treatment with the majority of deaths due to MDR-TB. Low baseline weight predicted a three-fold increased rate of death (aHR 3.1 95%CI 1.5-6.7) while individuals receiving highly active ART experienced a significantly lower rate of death compared to those who were not (aHR 0.4 95%CI 0.2-0.9). CONCLUSION: Early ART is likely a key component of effective MDR-TB management in co-infected individuals.

OBJETIVO: evaluar la prevalencia de estos síntomas y analizar su relación con la exposición a plaguicidas y el nivel de colinesterasa en trabajadores agrícolas. METODOLOGÍA: se realizó un estudio transversal analítico con 106 jornaleros en un campo agrícola en México. Se determinó el nivel de colinesterasa y los síntomas según la exposición. La exposición se delimitó con un índice constituido por 15 variables. RESULTADOS: la prevalencia de síntomas fue de 52 por cada 100 trabajadores. 31% refirió de 1 a 3, 16% de 4 a 9 síntomas y el 5% presentó más de 10. Hubo asociación entre días de exposición y síntomas persistentes p = 0.03. También entre nivel de exposición y presencia de síntomas probables y específicos. Los más expuestos tuvieron una probabilidad 20% mayor de tener síntomas. La concentración de colinesterasa estuvo dentro de rangos normales. Se detectó anemia en el 28% de la población. Esta fue tres veces más frecuente en las mujeres (p < 0,001). CONCLUSIONES: en este grupo fue posible identificar el aumento de síntomas persistentes en jornaleros con niveles de colinesterasa dentro de rangos habitualmente considerados normales. OBJECTIVE: to evaluate the prevalence of these symptoms and their relationship with pesticide exposure and the cholinesterase levels in agricultural workers. METHODOLOGY: an analytical cross-sectional study conducted in Mexico. Cholinesterase concentration and symptom frequency were assessed for 106 agricultural workers. Exposure was defined with a composed index of 15 variables. RESULTS: symptom prevalence was 52 out of 100 workers. 31% of workers had 1 to 3 of the symptoms, 16% had 4 to 9 of them and 5% had 10 or more of the symptoms. There was an association, p = 0.03, between days of exposure and persistent symptoms. Likewise, there was an association between exposure level and the presence of probable and specific symptoms. Patients with the highest exposure level had 20% more chances of exhibiting symptoms. Cholinesterase concentration ranges were normal. Anemia was detected in 28% of the population. It was three times as frequent in females as in males (p < 0.001). CONCLUSIONS:it was possible to identify the increase of persistent symptoms in workers with cholinesterase levels that are usually considered to be normal.

A new direct air-cooled single-effect LiBr–H2O absorption prototype is described and proposed for use in solar cooling. As distinguishing aspects, it presents: an adiabatic absorber using flat-fan sheets; an air-cooling system that directly refrigerates both the condenser and the absorber and; the possibility of being operated also as a double-effect unit. A solar facility comprising a 48 m2 field of flat-plate collectors was used to test the single-effect operation mode of the prototype. Results from an experimental campaign carried out in Madrid during summer 2010 are shown and operation parameters corresponding to two typical summer days are detailed. The prototype worked efficiently, with COP values around 0.6. Cooling power varied from 2 kW to 3.8 kW, which represented about 85% of the prototype’s nominal capacity. Chilled water temperatures mostly ranged between 14 °C and 16 °C, although the lowest measured value was of 12.8 °C. Condensation and absorption temperatures were under 50 °C and 46 °C, respectively, even with outdoor temperatures of 40 °C. Driving water temperature ranged between 85 °C and 110 °C. As a mean, the system was able to meet 65% of the cooling demand corresponding to a room of 40 m2. No signs of crystallization were observed during about a hundred hours of operation.

The structure of the low temperature phase of NH4MnF3 has been determined by means of X-ray powder diffraction using the Rietveld method. The structure is orthorhombic with space group Pnma, Z=4. The unit cell dimensions at T=83 K are a=5.952(1) AA, b=8.541(1) AA and c=5.949(1) AA. The low temperature Raman spectra have been interpreted consistently with the space group. The librational modes of the ammonium ion have been identified from the temperature dependence of the Raman lines. A model for the orientations of the NH4+ ions is proposed such that the minimum energy is achieved when each H atom points towards one of the four nearest F atoms. The depolarization of some of the Raman peaks in tentatively explained as an effect of orientational disorder of the NH4+ ions in the low temperature phase.

In this paper, data fusion based on multi-class support vector machines (SVM) is presented to detect and isolate three mechanical faults in induction motors. First, we construct the feature vector by using signatures created from frequency-domain characteristics. These signatures are obtained from mechanical vibration and line currents measurements. Then, the feature vector is used to feed SVM's to classify different motor conditions (normal, misalignment, unbalanced and bearing fault). Different experiments using a three phase induction motor were performed under variable operational conditions (motor speeds and load torque scenarios) in order to acquire training and validation data. The identified optimal parameters of the SVM's are reported. The SVM's are studied with two types of kernel functions, the radial basis and the polynomial functions. Data acquisition, feature extraction and SVM's computation were implemented by using LabView programming language. The experimental results show the effectiveness of the proposed approach in diagnosing the studied mechanical faults at different speeds and load conditions. In these experimental tests, the worst-case accuracy of the proposed method was 97.1%.

In order to know the present abundance and seasonal variability of the seals (Phoca vitulina richardsi Gray, 1864) hauling at the inner northwest portion of Punta Banda Estuary (Baja California, Mexico), 40 counts were carried out between November 1988 and August 1990. The average abundance during the study period was 52 individuals, although a significant seasonal variability was noted. The largest mean abundance occurred in spring (X = 69; n = 12; range = 31-110) and it was the best season to assess the number of seals that use the estuary. The lowest abundance was recorded in summer (X = 28; n = 5; range = 2-72) while in autumn the number of seals was lower than in winter and spring (X = 31; n = 8; range = 18-48). The maximum seal counts were noted in winter, although their average abundance was lower than in spring (X = 58; n = 15; range = 18-151) since the herd increased by the occasional presence of pups and juveniles. No relationship was found between the abundance of seals and the sea level. The seasonal variation in the size of the herd was associated with its breeding season which occurs late in winter and with herd movements to other near haul-out sites.

Los recorridos en los Senderos Submarinos del Parque Nacional Cahuitapermitieron identificar los organismos marinos presentes. La descripción biológica de la flora y la fauna se basó en la metodología de línea transecto y observación directa. El Sendero Submarino Perezoso presentó un 40% de cobertura de coral vivo, entre los cuales estaba el coral estrella (Siderastrea siderea) como dominante, las especies de peces más frecuente pertenecen a la familia Pomacentridae. El erizo negro (Diadema antillarum) es el más frecuente de los invertebrados y las algas registradas son del género Dictyota y la especie Halimeda opuntia. Las especies de coral Siderastrea siderea y Agaricia agaricites son las más frecuentes en los senderos submarinos de Perezoso y Eduardo. This survey provides biological information regarding the underwater trails of Cahuita National Park, and identifies the most common species present. The biological description of the flora and fauna are based on line transects and direct observation. The Perezoso underwater trail had 40% live coral cover, of which the Lobe coral (Siderastrea siderea) was the most common; the most common species of fish belonged to the family Pomacentridae. The long spined sea urchin (Diadema antillarum) was the most common among the invertebrates, and the algae recorded belonged to the genera Dictyota and Halimeda. The coral species Siderastrea siderea and Agaricia agaricites were the most common corals of the Perezoso and Eduardo underwater trails. Os percursos nas Trilhas Submarinas do Parque Nacional Cahuita permitiram identificar os organismos marinhos presentes. A descrição biológica da flora e da fauna baseou-se na metodologia de linha transepto e observação direta. A Trilha Submarina Perezoso apresentou 40% de cobertura de coral vivo, entre os quais estava o coral estrela (Siderastrea siderea) como dominante, as espécies de peixes mais frequente pertencem à família Pomacentridae. O ouriço-do-mar (Diadema antillarum) é o mais frequente dos invertebrados e as algas registradas são do gênero Dictyota e a espécie Halimeda opuntia. As espécies de coral Siderastrea siderea e Agaricia agaricites são as mais frequentes nas trilhas submarinas de Perezoso e Eduardo.&nbsp

We report the discovery of soliton-like electrogenerated chemiluminescence (ECL) waves in the electrochemical oxidation of thin films (15−250 nm) of the semiconducting conjugated polymer poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT). The ECL “wave fronts” were visualized and imaged in space and time by optical emission microscopy and observed to freely propagate parallel to the plane of the electrode. The data reveal that the EC solitons are triggered by the flux of electrolytes into the polymer film at nanoscale “leaks” (or defects) and propagate by a highly nonlinear, positive-feedback kinetic mechanism involving EC oxidation, mass transport of electrolyte anions, and oxidation-induced swelling, all taking place within the conjugated polymer film. Several model systems with spatially distributed reaction “triggers” were studied to elucidate the mechanistic details of this complex oxidation process in polymer films.

ZnO thin films grown by metal-organic vapor phase epitaxy along the nonpolar [formula: see text] direction and exhibiting semipolar [formula: see text] facets have been chemically etched with HCl. In order to get an insight into the influence of the ZnO wurtzite structure in the chemical reactivity of the material, Kelvin probe microscopy and convergent beam electron diffraction have been employed to unambiguously determine the absolute polarity of the facets, showing that [formula: see text] facets are unstable upon etching in an HCl solution and transform into [formula: see text] planes. In contrast, [formula: see text] facets undergo homogeneous chemical etching perpendicular to the initial crystallographic plane. The observed etching behavior has been explained in terms of surface oxygen dangling bond density, suggesting that the macroscopic polarity plays a secondary role in the etching process.

New insights on the molecular level details of the recently reported light-assisted injection of positive charge into single conjugated polymer chains are reported. Extensive new fluorescence-voltage single molecule spectroscopy (FV-SMS) measurements were performed on single chains of the archetypical conjugated polymer MEH-PPV embedded in a capacitor device to complement previous studies of the influence of the bias scan rate and optical excitation intensity. The use of a vacuum microscope allowed for the precise control of the device atmosphere, demonstrating the influence of triplet states in the MEH-PPV on the FV-SMS modulation. For identical device conditions, little variation was observed in the rate and yield of charging from molecule to molecule. Through the use of thicker supporting matrices and insulating polymer "blocking layers", it was determined that good electrical contact between the hole transport layers and the single molecules was necessary for charge injection. The results demonstrate the complexity of charge transfer processes at the interface of organic semiconductors and highlight the ability of single molecule methods to advance the understanding of such processes at the nanoscale.

Introducción. Presentamos los resultados de la evaluación de las Jornadas Complutenses de Investigación para alumnos de pregrado en Ciencias de la Salud, una actividad académica con dos años de experiencia y una participación de 1.434 alumnos, creada en nuestra universidad para impulsar en los alumnos de pregrado habilidades comunicativas y de metodología en investigación. Sujetos y métodos. Mediante una encuesta anónima se evaluó en los alumnos el grado de satisfacción e interés (aprender metodología científica, aprender a hablar en público, etc.) y también en los moderadores de mesas (originalidad, planteamiento metodológico, presentación iconográfica, exposición oral, viabilidad y relevancia de las comunicaciones presentadas). Resultados. En las I Jornadas se inscribieron 500 alumnos, todos de la Universidad Complutense de Madrid (UCM), y se presentaron un total de 169 comunicaciones (129 orales, 40 pósters). En las II Jornadas lo hicieron 934 alumnos, 838 de la UCM y 96 de otras nueve universidades, y se presentaron un total de 286 comunicaciones (180 orales, 106 pósteres). Conclusiones. Es una actividad en la que el alumno pasa a ser un gestor activo y difusor de aprendizaje, y potencia de una manera dinámica habilidades en comunicación científica. También tiene beneficios para el profesorado y la institución universitaria, que la convierten en una ‘terapia pedagógica holística'.