Carbon Dioxide emissions from an Acacia plantation on peatland in Sumatra, Indonesia

Abstract. Peat surface CO2 emission, groundwater table depth and peat temperature were monitored for two years along transects in an Acacia plantation on thick tropical peat (>4 m) in Sumatra, Indonesia. A total of 2300 emission measurements were taken at 144 locations. The autotrophic root respiration component of the CO2 emission was separated from heterotrophic emissions caused by peat oxidation in three ways: (i) by comparing CO2 emissions within and beyond the tree rooting zone, (ii) by comparing CO2 emissions with and without peat trenching (i.e. cutting any roots remaining in the peat beyond the tree rooting zone), and (iii) by comparing CO2 emissions before and after Acacia tree harvesting. On average, the contribution of root respiration to daytime CO2 emission is 21 % along transects in mature tree stands. At locations 0.5 m from trees this is up to 80 % of the total emissions, but it is negligible at locations more than 1.3 m away. This means that CO2 emission measurements well away from trees are free of any root respiration contribution and thus represent only peat oxidation emission. We find daytime mean annual CO2 emission from peat oxidation alone of 94 t ha−1 yr−1 at a mean water table depth of 0.8 m, and a minimum emission value of 80 t ha−1 yr−1 after correction for the effect of diurnal temperature fluctuations, which resulted in a 14.5 % reduction of the daytime emission. There is a positive correlation between mean long-term water table depths and peat oxidation CO2 emission. However, no such relation is found for instantaneous emission/water table depth within transects and it is clear that factors other than water table depth also affect peat oxidation and total CO2 emissions. The increase in the temperature of the surface peat due to plantation development may explain over 50 % of peat oxidation emissions.

Sensitivity of wetland methane emissions to model assumptions: application and model testing against site observations

Abstract. Methane emissions from natural wetlands and rice paddies constitute a large proportion of atmospheric methane, but the magnitude and year-to-year variation of these methane sources is still unpredictable. Here we describe and evaluate the integration of a methane biogeochemical model (CLM4Me; Riley et al., 2011) into the Community Land Model 4.0 (CLM4CN) in order to better explain spatial and temporal variations in methane emissions. We test new functions for soil pH and redox potential that impact microbial methane production in soils. We also constrain aerenchyma in plants in always-inundated areas in order to better represent wetland vegetation. Satellite inundated fraction is explicitly prescribed in the model because there are large differences between simulated fractional inundation and satellite observations. A rice paddy module is also incorporated into the model, where the fraction of land used for rice production is explicitly prescribed. The model is evaluated at the site level with vegetation cover and water table prescribed from measurements. Explicit site level evaluations of simulated methane emissions are quite different than evaluating the grid cell averaged emissions against available measurements. Using a baseline set of parameter values, our model-estimated average global wetland emissions for the period 1993–2004 were 256 Tg CH4 yr−1, and rice paddy emissions in the year 2000 were 42 Tg CH4 yr−1. Tropical wetlands contributed 201 Tg CH4 yr−1, or 78 % of the global wetland flux. Northern latitude (>50 N) systems contributed 12 Tg CH4 yr−1. We expect this latter number may be an underestimate due to the low high-latitude inundated area captured by satellites and unrealistically low high-latitude productivity and soil carbon predicted by CLM4. Sensitivity analysis showed a large range (150–346 Tg CH4 yr−1) in predicted global methane emissions. The large range was sensitive to: (1) the amount of methane transported through aerenchyma, (2) soil pH (± 100 Tg CH4 yr−1), and (3) redox inhibition (± 45 Tg CH4 yr−1).

A simple equivalent circuit analysis of rectangular folded-waveguide slow-wave structure

A simple yet accurate equivalent circuit model was developed for the analysis of slow-wave properties (dispersion and interaction impedance characteristics) of a rectangular folded-waveguide slow-wave structure. Present formulation includes the effects of the presence of beam-hole in the circuit, which were ignored in existing approaches. The analysis was benchmarked against measurement as well as with 3D electromagnetic modeling using MAFIA for two typical slow-wave structures operating in Ka- and Q-bands, and close agreements were observed. The analysis was extended for demonstrating the effect of the variation of beam-hole radius on the RF interaction efficiency of the device. (C) 2009 Elsevier GmbH. All rights reserved.

Reaction of polyperoxides with triphenylphosphine

The triphenylphosphine deoxygenation of the polyperoxides, poly(styrene peroxide), poly(methyl methacrylate peroxide), and poly(alpha-methylstyrene peroxide) proceed via the phosphorane intermediates, which in the presence of moisture hydrolyze to give the respective diols. At higher temperatures and under dry conditions the phosphorane decomposes into epoxide and triphenylphosphine oxide. The reaction has been studied by H-1-, C-13-, and P-31-NMR spectroscopy. The results obtained are consistent with a concerted insertion of the biphile, triphenylphosphine, into the peroxy bond and this reaction pathway seems to be new as far as the chemistry of polyperoxides is concerned. Though the aim of this investigation was to test the selective deoxygenation of polyperoxide by triphenylphosphine as a method of preparing polyethers, it turned out to be a fruitful method of synthesis of stereospecific diols. (C) 1997 John Wiley & Sons, Inc.

Synthesis of a mixed-metal spinel, NiMn2O4, through site-selective substitution in MOF, (NiMn2){C6H3(COO)(3)}(2)]: synthesis, structure and magnetic studies

A mixed-metal metal-organic framework (MOF) compound NiMn2{C6H3(COO)(3)}(2)], I, is prepared hydrothermally by replacing one of the octahedral Mn2+ ions in Mn-3{C6H3(COO)(3)}(2)] by Ni2+ ions. Magnetic studies on I suggest antiferromagnetic interactions with weak canted antiferromagnetism below 8 K. On heating in flowing air I transforms to NiMn2O4 spinel at low temperature (T < 400 degrees C). The thermal decomposition of I at different temperatures results in NiMn2O4 with particle sizes in the nano regime. The nanoparticle nature of NiMn2O4 was confirmed using PXRD and TEM studies. Magnetic studies on the nanoparticles of NiMn2O4 indicate ferrimagnetism. The transition temperature of NiMn2O4 nanoparticles exhibits a direct correlation with the particle size. This study highlights the usefulness of MOF compound as a single-source precursor for the preparation of important ceramic oxides with better control on the stoichiometry and particle size.

Rv1027c-Rv1028c encode functional KdpDE two - Component system in Mycobacterium tuberculosis

In Mycobacterium tuberculosis Rv1027c-Rv1028c genes are predicted to encode KdpDE two component system, which is highly conserved across all bacterial species. Here, we show that the system is functionally active and KdpD sensor kinase undergoes autophosphorylation and transfers phosphoryl group to KdpE, response regulator protein. We identified His(642) and Asp(52) as conserved phosphorylation sites in KdpD and KdpE respectively and by SPR analysis confirmed the physical interaction between them. KdpD was purified with prebound divalent ions and their importance in phosphorylation was established using protein refolding and ion chelation approaches. Genetically a single transcript encoded both KdpD and KdpE proteins. Overall, we report that M. tuberculosis KdpDE system operates like a canonical two component system. (C) 2014 Elsevier Inc. All rights reserved.

Retinoic Acid and Iron Metabolism: A Step Towards Design of a Novel Antitubercular Drug

The scenario of tuberculosis has gone deadly due to its high prevalence and emergence of widespread drug resistance. It is now high time to develop novel antimycobacterial strategies and to understand novel mechanisms of existing antimycobacterial compounds so that we are equipped with newer tuberculosis controlling molecules in the days to come. Iron has proven to be essential for pathogenesis of tuberculosis and retinoic acid is known to influence the iron metabolism pathway. Retenoic acid is also known to exhibit antitubercular effect in in vivo system. Therefore there is every possibility that retinoic acid by affecting the iron metabolism pathway exhibits its antimycobacterial effect. These aspects are reviewed in the present manuscript for understanding the antimycobacterial role of retinoic acid in the context of iron metabolism and other immunological aspects.

Review on Tin (II) Sulfide (SnS) Material: Synthesis, Properties, and Applications

Tin (II) sulphide (SnS), a direct band gap semiconductor compound, has recently received great attention due to its unique properties. Because of low cost, absence of toxicity, and good abundance in nature, it is becoming a candidate for future multifunctional devices particularly for light conversion applications. Although the current efficiencies are low, the cost-per-Watt is becoming competitive. At room temperature, SnS exhibits stable low-symmetric, double-layered orthorhombic crystal structure, having a = 0.4329, b = 1.1192, and c = 0.3984nm as lattice parameters. These layer-structured materials are of interest in various device applications due to the arrangement of structural lattice with cations and anions. The layers of cations are separated only by van der Waals forces that provide intrinsically chemically inert surface without dangling bonds and surface density of states. As a result, there is no Fermi level pinning at the surface of the semiconductor. This fact leads to considerably high chemical and environmental stability. Further, the electrical and optical properties of SnS can be easily tailored by modifying the growth conditions or doping with suitable dopants without disturbing its crystal structure.In the last few decades, SnS has been synthesized and studied in the form of single-crystals and thin-films. Most of the SnS single-crystals have been synthesized by Bridgeman technique, whereas thin films have been developed using different physical as well as chemical deposition techniques. The synthesis or development of SnS structures in different forms including single-crystals and thin films, and their unique properties are reviewed here. The observed physical and chemical properties of SnS emphasize that this material could has novel applications in optoelectronics including solar cell devices, sensors, batteries, and also in biomedical sciences. These aspects are also discussed.

On the detection of human influence in extreme precipitation over India

Climate change is expected to influence extreme precipitation which in turn might affect risks of pluvial flooding. Recent studies on extreme rainfall over India vary in their definition of extremes, scales of analyses and conclusions about nature of changes in such extremes. Fingerprint-based detection and attribution (D&A) offer a formal way of investigating the presence of anthropogenic signals in hydroclimatic observations. There have been recent efforts to quantify human effects in the components of the hydrologic cycle at large scales, including precipitation extremes. This study conducts a D&A analysis on precipitation extremes over India, considering both univariate and multivariate fingerprints, using a standardized probability-based index (SPI) from annual maximum one-day (RX1D) and five-day accumulated (RX5D) rainfall. The pattern-correlation based fingerprint method is used for the D&A analysis. Transformation of annual extreme values to SPI and subsequent interpolation to coarser grids are carried out to facilitate comparison between observations and model simulations. Our results show that in spite of employing these methods to address scale and physical processes mismatch between observed and model simulated extremes, attributing changes in regional extreme precipitation to anthropogenic climate change is difficult. At very high (95%) confidence, no signals are detected for RX1D, while for the RX5D and multivariate cases only the anthropogenic (ANT) signal is detected, though the fingerprints are in general found to be noisy. The findings indicate that model simulations may underestimate regional climate system responses to increasing human forcings for extremes, and though anthropogenic factors may have a role to play in causing changes in extreme precipitation, their detection is difficult at regional scales and not statistically significant. (C) 2015 Elsevier B.V. All rights reserved.

Elastic Waves in a Hybrid Multilayered Piezoelectric Plate

An analytical-numerical method is presented for analyzing dispersion and characteristic surface of waves in a hybrid multilayered piezoelectric plate. In this method, the multilayered piezoelectric plate is divided into a number of layered elements with three-nodal-lines in the wall thickness, the coupling between the elastic field and the electric field is considered in each element. The associated frequency dispersion equation is developed and the phase velocity and slowness, as well as the group velocity and slowness are established in terms of the Rayleigh quotient. Six characteristic wave surfaces are introduced to visualize the effects of anisotropy and piezoelectricity on wave propagation. Examples provide a full understanding for the complex phenomena of elastic waves in hybrid multilayered piezoelectric media.

"Aplicación de un sistema multimétrico para evaluar la calidad del agua superficial en la microcuenca El Coyote del Rio Estelí, Nicaragua"

En la microcuenca El Coyote localizada en el municipio de Condega, Estelí, se evaluó la calidad del agua superficial de sde febrero del 2010 a febrero del 2011. El propósito fue la identificación de indicadores que faciliten la vigilancia y monitoreo de la calidad del agua . Se integró un sistema multimétrico utilizando las características físicoquímicas y bacteriológicas, macro invertebrados acuáticos, la caracterización morfométrica de la microcuenca y la información resultante a nivel de comunidad (cambios en el uso del suelo). En la determinación de la relación de la calidad del agua con la estructura de la macrofauna acuática (macroinvertebrados) se usó el método Biological Monitoring Working Party (BMWP/Col ) . La microcuenca tiene 144 afluentes con una forma oval - oblonga - alargada, y su curva hipsométrica refleja un estado de equilibrio relativo de juvenil a madurez. El uso del suelo es inadecuado y su entorno natural fue valorado como subóptimo. Aunque los parámetros fisico químicos indicaron que las aguas son alcalinas, con un nivel aceptable de oxigeno disuelto, categorizadas según el Diagrama de Riverside como aguas aptas par a riego (C2 - S1), y aceptables según valores determinados para DBO 5 y DQO; sin embargo, requieren de un tratamiento de descontaminación previo a su uso doméstico y agropecuario. Además, debido a la presencia de coliformes fecales estas aguas no están aptas para consumo humano . Los macroinvertebrados varían, según la estacionalidad, en riqueza, abundancia y distribución, presentando una disminución en el número de individuos en la época lluviosa (t= 5.21, p<2.18E - 07). E l 6 8 . 91 % de los macroinvertebrados bioin dicadores se distribuyeron en cinco familias : Leptohyphidae , Baetidae , Hydropsychidae , Chironomidae y Physidae , siendo el cariotipo piedra el que present ó mayor diversidad y abundancia . El promedio del BMWP /Col fue de 60.06, indicando una calidad del agua entre dudosa y aceptable , y el índice ASPT de 6.71 señala una contaminación moderada ; estos resultados coincide n con los obtenidos utilizando la batería de indicadores fisicoquímicos y bacteriológicos .

锥形流乘波体优化设计研究

随着马赫数的升高,波阻和摩阻增加,形成升阻比“屏障”,而乘波构型飞行器是克服这一屏障的有效途径.本文在Ma∞=4.0～20.0、高度H=24.0～52.0 km、圆锥角Ac=5°～10°的条件下,以升阻比为目标函数,进行了乘波体的优化设计,讨论了对乘波体优化外形的影响因素,并给出全马赫数范围的优化乘波体外形及其气动力结果.

Estudio de la eficiencia de utilización del fertilizante nitrogenado en los pastos bajo las condiciones de la III región (Managua)

Se realizó un estudio a partir de la recopilación de diferentes trabajos experimentales y en condiciones de producción realizados bajo las características de la Calera, Chiltepe y ANILIB, en el tema de fertilización nitrogenada en los pastos: estrella (Cynodon nlemfluensis), bermuda coastal (Cynodon dactylon vs coastal) y sorgo forrajero (Sorghum vulgare). Donde se compararon dosis de O, 40, 80, 90, 100, 200, 400, 600, 800 Kg N/ha/año respectivamente. Para analizar la eficiencia técnica del fertilizante se estimaron regresiones entre el rendimiento y el nivel de nitrógeno, y al calcular la respuesta igualmente se estimó la regresión entre la eficiencia de conversión (Kg MS/Kg N aplicado) y el nivel de nitrógeno, encontrándose buenos ajustes con las funciones cuadráticas (r= 0.9, 0.5) para rendimiento y respuesta respectivamente. Obteniéndose la máxima de conversión con dosis de 200 - 300 Kg N/ha/año. Además la amplia serie de niveles de N permitió conocer el potencial de respuesta de diferentes pastos durante la estación lluviosa y seca, siendo en esta última donde se produjo los más bajos valores de rendimiento. Se encontraron el mayor efecto del nivel de fertilización que de la edad. Así como la diferencia entre las especies estudiadas, resultando superior el pasto estrella en un 69% que el sorgo. Por otra parte la fuente nitrógeno aplicado fue superior al utilizar sulfato de amonio con dosis elevada y el nitrato de amonio con aplicaciones bajas de nitrógeno.