3,135 research outputs found

    Generalized Competing Glauber-type Dynamics and Kawasaki-type Dynamics

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    In this article, we have given a systematic formulation of the new generalized competing mechanism: the Glauber-type single-spin transition mechanism, with probability p, simulates the contact of the system with the heat bath, and the Kawasaki-type spin-pair redistribution mechanism, with probability 1-p, simulates an external energy flux. These two mechanisms are natural generalizations of Glauber's single-spin flipping mechanism and Kawasaki's spin-pair exchange mechanism respectively. On the one hand, the new mechanism is in principle applicable to arbitrary systems, while on the other hand, our formulation is able to contain a mechanism that just directly combines single-spin flipping and spin-pair exchange in their original form. Compared with the conventional mechanism, the new mechanism does not assume the simplified version and leads to greater influence of temperature. The fact, order for lower temperature and disorder for higher temperature, will be universally true. In order to exemplify this difference, we applied the mechanism to 1D Ising model and obtained analytical results. We also applied this mechanism to kinetic Gaussian model and found that, above the critical point there will be only paramagnetic phase, while below the critical point, the self-organization as a result of the energy flux will lead the system to an interesting heterophase, instead of the initially guessed antiferromagnetic phase. We studied this process in details.Comment: 11 pages,1 figure

    QUANTIFICATION OF L-ASCORBIC ACID AND D-ISO-ASCORBIC ACID IN JELLIES FRUIT BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

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    QUANTIFICATION OF L-ASCORBIC ACID AND D-ISO-ASCORBIC ACID IN JELLIES FRUIT BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY. Ascorbic acid has important nutritional characteristics such as high antioxidant potential, preventing diverse damage and diseases in the tissues and the process of aging. Different isomeric forms of the ascorbic acid can be found in nature and each one have different potential antioxidant and different activity pro-vitamin C. This work examined a method to detect and quantify the isomers L-ascorbic acid (LAA) and D-iso-ascorbic acid (DIAA) in jelly fruit. The method showed acceptable selectivity, linearity, repeatability and recovery. DIAA was not found in the analyzed samples, but LAA was found up to 605 mg in 100 g of sample.3551020102

    A New Cyclometalation Motif: Synthesis, Characterization, Structures, and Reactivity of Pallada- and Platinacycles with a Bidentate {C(sp2,cyrhetrene),N}− Ligand

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    The synthesis, characterization, X-ray crystal structure, and study of the reactivity of the novel cyretrenyl ligand [{(η5-C5H4-2-C5H4N)}Re(CO)3 (1) with Pd(OAc)2 or [MCl2(DMSO)2] (M = Pd, Pt) are reported. These studies have allowed us to obtain the bis-μ-ligand cyclopalladated complexes [Pd{[k2-C,N-(η5-C5H3)-2(C5H4N)]Re(CO)3)}(μ-X)]2 (X = OAc (2a), Cl (4a)) and monomeric pallada- and platinacycles of the general formula [M{[k2-C,N-(η5-C5H3)-2(C5H4N)]Re- (CO)3}(X)(L)] (M = Pd, L = PPh3, X = OAc (3a), Cl (5a); M = Pd, L = DMSO, X = Cl (6a); M = Pt, X = Cl, L = PPh3 (5b), DMSO (6b)), where compound 1 acts as a {C(sp2,cyrhetrene),N} bidentate ligand. All complexes were characterized by elemental analyses, infrared spectroscopy, and one- and twodimensional NMR. The X-ray crystal structures of 5a 3 1/2CH2Cl2, 5b, 6a 3CH2Cl2, and 6b confirm (a) the existence of the five-membered metallacycle, (b) the {C(sp2,cyrhetrene),N} mode of binding of the metallo ligand 1, and (c) the cis arrangement between the metalated carbon and the neutral L ligands (PPh3 or DMSO) in these products. A comparative study of the structures, spectroscopic properties, and reactivities of the new cyclometalated compounds and those of their analogues with a bidentate {C(sp2,ferrocene),N} ligand is also reported

    What do the instruments of classroom observation reveal to us about mathematic classes in schools with improved trajectory?

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    El presente estudio analiza la capacidad de dos instrumentos de observación de aula, Classroom Assessment Scoring System (CLASS) y Mathematical Quality of Instruction (MQI), para describir el funcionamiento de aulas de matemática que pertenecen a escuelas municipales chilenas con trayectorias de mejoramiento. En concreto, se busca indagar, por una parte, cómo ambos instrumentos correlacionan y coinciden en encontrar determinados rasgos de la enseñanza, y por otra, en las descripciones cualitativas que esconden los puntajes asignados a cada sala. Los resultados nos indican, por un lado, que solamente la dimensión Diálogo Instruccional de CLASS correlaciona significativamente con algunas de las dimensiones de MQI y que los puntajes asignados a las aulas efectivamente permiten discriminar la calidad o frecuencia con que cada rasgo de la enseñanza aparece en cada aula. Sin embargo, las descripciones cualitativas mostraron que en cada sala es posible encontrar múltiples rasgos positivos de la enseñanza que permitieron a los profesores conducir una buena clase de matemática, con errores y elementos ausentes, pero que fueron reemplazados exitosamente por otros elementos de la enseñanza efectiva.This study analyzes the capacity of two classroom observation instruments, Classroom Assessment Scoring System (CLASS) and Mathematical Quality of Instruction (MQI), to describe the functioning of mathematical classrooms in Chilean public schools with improved trajectories. In fact, it seeks to investigate how the two instruments correlate and agree on finding certain traits of teaching, and the qualitative descriptions that hide the scores assigned to each room. Results indicate that just the Instructional Dialogue dimension of CLASS correlates significantly with some of the dimensions of MQI, and that the scores assigned to the classrooms effectively discriminate the quality or frequency with which each trait of teaching appears in every class. However, qualitative descriptions showed that in each classroom it is possible to find multiple positive traits of teaching that allowed teachers to lead a good mathematics class, with errors and absent elements, but which were successfully replaced by other elements of effective teaching

    Epidemiological and clinical characteristics of children hospitalized due to influenza A and B in the south of Europe, 2010-2016

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    Influenza produces annual epidemics that affect 5-15% of the world population. Complications and hospitalizations are more frequent in childhood. This study describes and analyses the epidemiological and clinical characteristics of children hospitalized due to confirmed influenza in influenza surveillance sentinel hospitals in Catalonia. Retrospective descriptive study conducted in six influenza seasons (2010-2011 to 2015-2016) in persons aged 0-17 years diagnosed with laboratory-confirmed influenza requiring hospitalization. 291 cases were notified to the health authorities: 79.4% were due to the influenza A virus and 20.6% to the B virus. The most common subtype was H1N1 with 57.6% of cases: 52.6% were male, 56.7% were aged <2 years, and 24.4% were aged <1 year. 62.2% of cases had pneumonia, 26.8% acute respiratory distress syndrome and 11.7% bacterial pneumonia. 5.8% of cases were vaccinated and 21.3% required intensive care unit admission, of whom 54.8% were aged <2 years. There were 3 deaths, all with influenza A infection. Influenza A cases were younger than influenza B cases (OR 3.22; 95% CI: 1.73-6.00). Conclusion: Children aged <2 years are especially vulnerable to the A H1N1 virus, including those without pre-existing chronic disease. These results are relevant for the planning of vaccination programs to improve maternal and child health

    Encapsulation of Phenolic Compounds from a Grape Cane Pilot-Plant Extract in Hydroxypropyl Beta-Cyclodextrin and Maltodextrin by Spray Drying

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    Grape canes, the main byproducts of the viticulture industry, contain high-value bioactive phenolic compounds, whose application is limited by their instability and poorly solubility in water. Encapsulation in cyclodextrins allows these drawbacks to be overcome. In this work, a grape cane pilot-plant extract (GCPPE) was encapsulated in hydroxypropyl beta-cyclodextrin (HP-β-CD) by a spray-drying technique and the formation of an inclusion complex was confirmed by microscopy and infrared spectroscopy. The phenolic profile of the complex was analyzed by LC-ESI-LTQ-Orbitrap-MS and the encapsulation efficiency of the phenolic compounds was determined. A total of 42 compounds were identified, including stilbenes, flavonoids, and phenolic acids, and a complex of (epi)catechin with β-CD was detected, confirming the interaction between polyphenols and cyclodextrin. The encapsulation efficiency for the total extract was 80.5 ± 1.1%, with restrytisol showing the highest value (97.0 ± 0.6%) and (E)-resveratrol (32.7 ± 2.8%) the lowest value. The antioxidant capacity of the inclusion complex, determined by ORAC-FL, was 5300 ± 472 µmol TE/g DW, which was similar to the value obtained for the unencapsulated extract. This formulation might be used to improve the stability, solubility, and bioavailability of phenolic compounds of the GCPPE for water-soluble food and pharmaceutical applications

    Evolution favors protein mutational robustness in sufficiently large populations

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    BACKGROUND: An important question is whether evolution favors properties such as mutational robustness or evolvability that do not directly benefit any individual, but can influence the course of future evolution. Functionally similar proteins can differ substantially in their robustness to mutations and capacity to evolve new functions, but it has remained unclear whether any of these differences might be due to evolutionary selection for these properties. RESULTS: Here we use laboratory experiments to demonstrate that evolution favors protein mutational robustness if the evolving population is sufficiently large. We neutrally evolve cytochrome P450 proteins under identical selection pressures and mutation rates in populations of different sizes, and show that proteins from the larger and thus more polymorphic population tend towards higher mutational robustness. Proteins from the larger population also evolve greater stability, a biophysical property that is known to enhance both mutational robustness and evolvability. The excess mutational robustness and stability is well described by existing mathematical theories, and can be quantitatively related to the way that the proteins occupy their neutral network. CONCLUSIONS: Our work is the first experimental demonstration of the general tendency of evolution to favor mutational robustness and protein stability in highly polymorphic populations. We suggest that this phenomenon may contribute to the mutational robustness and evolvability of viruses and bacteria that exist in large populations

    Distinct Gene Expression and Epigenetic Signatures in Hepatocyte-like Cells Produced by Different Strategies from the Same Donor

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    Summary: Hepatocyte-like cells (HLCs) can be generated through directed differentiation or transdifferentiation. Employing two strategies, we generated induced pluripotent stem cell (iPSC)-HLCs and hiHeps from the same donor cell line. Both types of HLCs clustered distinctly from each other during gene expression profiling. In particular, differences existed in gene expression for phase II drug metabolism and lipid accumulation, underpinned by H3K27 acetylation status in iPSC-HLCs and hiHeps. While distinct phenotypes were achieved in vitro, both types of HLCs demonstrated similar phenotypes following transplantation into Fah-deficient mice. In conclusion, functional HLCs can be obtained from the same donor using two strategies. Global gene expression defined the differences between those populations in vitro. Importantly, both HLCs displayed partial but markedly improved hepatic function following transplantation in vivo, demonstrating plasticity and the potential for cell-based modeling in the dish and cell-based therapy in the future. : In this article, Hui and colleagues show that hiHeps and iPSC-HLCs generated from the same donor display different gene expression patterns that correlate with their hepatic functions. Distinct H3K27ac modifications partially explain the functional differences between the two types of HLCs. Importantly, both HLCs show improved hepatic gene expression after repopulation in murine livers. Keywords: transdifferentiation, directed differentiation, hepatocyte-like cells, gene expression patter
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