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Aim The variation in species composition among sites, or beta diversity, can be decomposed into replacement and richness difference. A debate is ongoing in the literature concerning the best ways of computing and interpreting these indices. This paper first reviews the historical development of the formulae for decomposing dissimilarities into replacement, richness difference and nestedness indices. These formulae are presented for species presence-absence and abundance using a unified algebraic framework. The indices decomposing beta play different roles in ecological analysis than do beta-diversity indices. Innovation Replacement and richness difference indices can be interpreted and related to ecosystem processes. The pairwise index values can be summed across all pairs of sites; these sums form a valid decomposition of total beta diversity into total replacement and total richness difference components. Different communities and study areas can be compared: some may be dominated by replacement, others by richness/abundance difference processes. Within a region, differences among sites measured by these indices can then be analysed and interpreted using explanatory variables or experimental factors. The paper also shows that local contributions of replacement and richness difference to total beta diversity can be computed and mapped. A case study is presented involving fish communities along a river. Main conclusions The different forms of indices are based upon the same functional numerators. These indices are complementary; they can help researchers understand different aspects of ecosystem functioning. The methods of analysis used in this paper apply to any of the indices recently proposed. Further work, based on ecological theory and numerical simulations, is required to clarify the precise meaning and domain of application of the different forms. The forms available for presence-absence and quantitative data are both useful because these different data types allow researchers to answer different types of ecological or biogeographic questions. [ABSTRACT FROM AUTHOR]

Usually, the treatment of oil sludge produced from polymer flooding (OSPPF) in offshore oilfield needs transport and incineration. It is time‐consuming and high‐economic cost. In this paper, firstly, the OSPPF in an offshore oilfield was analyzed by IR, SEM, EDS, and XRD and its formation mechanism was discussed. Then, chemical degradation was proposed according to the formation mechanism. Mixture of H2O2 and diethylene triamine pentacetic acid (DTPA) was chosen for the chemical degradation of OSPPF. The effects of different factors on degradation rate were studied and the national condition was obtained as follows: 3 g OSPPF, 3 g kerosene, and 9 g aqueous solutions containing 5 wt% H2O2+ DTPA (H2O2:DTPA was 1:1) were mixed at 65°C for 12 hour. After the degradation, the oil in the OSPPF can be recovered and polymer gel in the OSPPF can be destroyed completely. This chemical degradation is a good choice for treatment of OSPPF in situ. In this paper, the composition and causation of OSPPF produced from one offshore oilfield was analyzed firstly and then it was treated by chemical degradation. The chemical degradation is a good choice for in situ treatment of OSPPF for the offshore oilfield. To our knowledge, this is the first study for treatment of OSPPF produced from offshore oilfield in situ by chemical degradation. [ABSTRACT FROM AUTHOR]

Deploying energy storage and carbon capture at scale is hindered by the substantial endothermic penalty of decomposing CaCO3 to CaO and CO2, and the rapid loss of CO2 absorption capacity by CaO sorbent particles due to sintering at the high requisite decomposition temperatures. The decomposition reaction mechanism underlying sorbent deactivation remains unclear at the atomic level and nanoscale due to past reliance on postmortem characterization methods with insufficient spatial and temporal resolution. Thus, elucidating the important CaCO3 decomposition reaction pathway requires direct observation by time‐resolved (sub‐)nanoscale methods. Here, chemical and structural dynamics during the decomposition of CaCO3 nanoparticles to nanoporous CaO particles comprising high‐surface‐area CaO nanocrystallites are examined. Comparing in situ transmission electron microscopy (TEM) and synchrotron X‐ray diffraction experiments gives key insights into the dynamics of nanoparticle calcination, involving anisotropic CaCO3 thermal distortion before conversion to thermally dilated energetically stable CaO crystallites. Time‐resolved TEM uncovered a novel CaO formation mechanism involving heterogeneous nucleation at extended CaCO3 defects followed by sweeping reaction front motion across the initial CaCO3 particle. These observations clarify longstanding, yet incomplete, reaction mechanisms and kinetic models lacking accurate information about (sub‐)nanoscale dynamics, while also demonstrating calcination of CaCO3 without sintering through rapid heating and precise temperature control. [ABSTRACT FROM AUTHOR]

Ascorbate content in plants is controlled by its synthesis from carbohydrates, recycling of the oxidized forms and degradation. Of these pathways, ascorbate degradation is the least studied and represents a lack of knowledge that could impair improvement of ascorbate content in fruits and vegetables as degradation is non-reversible and leads to a depletion of the ascorbate pool. The present study revealed the nature of degradation products using [14C]ascorbate labelling in tomato, a model plant for fleshy fruits; oxalate and threonate are accumulated in leaves, as is oxalyl threonate. Carboxypentonates coming from diketogulonate degradation were detected in relatively insoluble (cell wall-rich) leaf material. No [14C]tartaric acid was found in tomato leaves. Ascorbate degradation was stimulated by darkness, and the degradation rate was evaluated at 63% of the ascorbate pool per day, a percentage that was constant and independent of the initial ascorbate or dehydroascorbic acid concentration over periods of 24 h or more. Furthermore, degradation could be partially affected by the ascorbate recycling pathway, as lines under-expressing monodehydroascorbate reductase showed a slight decrease in degradation product accumulation. [ABSTRACT FROM AUTHOR]

This paper focuses on the deformation origin of PbZr0.52Ti0.48O3 ( PZT) fiber mats obtained by electrospinning. The main cause of deformation of the green mats during heating was found to be a nonuniform relaxation of the stretched PVP polymer, due to nonuniform thermal decomposition of the Pb-hexanoate in the fibers. This relaxation starts under 100°C, well below the polymer decomposition temperature. The shrinkage was found to accelerate above the polymer glass transition point, giving rise to an overall linear change of almost 50%. The 'green' PZT mats were easily separated from the collector by first depositing a pure PVP sublayer on the collector. An optimal fabrication and slow multistep thermal treatment process that provides fiber mats with desired PZT phase and overcomes the nonuniform deformation is described. [ABSTRACT FROM AUTHOR]

A number of control schemes including nonlinear feedback, dislocated feedback, and speed feedback have been proposed and assessed for a bromate-malonic acid-cerium Belousov-Zhabotinsky batch reaction process. The tuning parameters of the Oregonator model were firstly adjusted based on a UV-vis spectrophotometric analysis in the experimental part of the research. The adjusted Oregonator model successfully reproduced the innate induction time and periodicity of the BZ-batch system. Subsequently, the controllers were implemented and numerical simulations were carried out by employing the multi-stage Adomian decomposition method. The nominal analysis method was used to study the linear stability of each design. All the controlled systems were found to be linearly stable for certain continuous regions of controller gain. The performance of the proposed control laws was assessed and the dislocated feedback control strategy was shown to be able to drive the system states toward desired setpoints quickly. Furthermore, the validity of the dislocated feedback control design was doubly ensured by the sliding mode control theory. It was found that those feedback schemes which manipulate cerium ion concentration can be practically realized by means of electrochemical oxidation or oxygen aeration. Our results were confirmed by the Simulink software package and the block diagram representations are included in the paper. [ABSTRACT FROM AUTHOR]

Equilibrium conditions of the main reactions of the SI cycle were studied in this paper. The extent of reaction for two main reactions of this cycle including sulfuric acid decomposition and hydrogen iodide decomposition was evaluated as a function of temperature, pressure, and initial mole number of reactants. In the reaction modelling of sulfuric acid and sulfur trioxide decompositions, two models including simple and multiple reaction models were considered. In the simple model, it was assumed that two decomposition reactions proceeded independently. However, in the multiple reaction model, both reactions were considered simultamneously. It was shown that the Bunsen reaction completely proceeded in the range of operating conditions of the Bunsen reactor. Also, sulfuric acid was demonstrated to be decomposed at a higher rate when the reaction temperature and initial concentration of the sulfuric acid and sulfur trioxide increased. Furthermore, the operating pressure had to be maintained at lower values and the generated sulfur dioxide had to be withdrawn from the reactor in order to have a higher yield of product in this reactor. Finally, in the hydrogen iodide decomposition, the operating pressure, temperature, and concentration of hydrogen iodide had to be maintained at higher values to have a complete reaction. Moreover, the generated hydrogen was shown to be withdrawn from the hydrogen iodide reactor to prevent from backward reaction. [ABSTRACT FROM AUTHOR]

The Hall-Yarborough equation (H-Y equation) of state has been favoured in natural gas engineering due to its accuracy and conciseness for many years. In this paper, the Adomian decomposition method (ADM) is employed to devise a novel algorithm for calculating the compressibility factors of natural gases through this reliable equation of state. A convergence accelerator technique, namely the efficient Shanks transform, is also exploited to further improve our scheme in terms of computational speed. Unlike most of the previous numerical solution strategies, our algorithm does not require an initial guess as the starting point and is computationally efficient. The proposed algorithm is found to be superior over the common Newton-Raphson algorithm, where we have also demonstrated that the latter can easily lead to grossly erroneous solutions. For the sake of illustration, a number of real-world case study problems are solved by our algorithm and relevant comparisons are provided. [ABSTRACT FROM AUTHOR]

The higher operating temperatures in gas-turbine engines enabled by thermal barrier coatings ( TBCs) engender new materials issues, viz silicate particles (sand, volcanic ash, fly ash) ingested by the engine melt on the hot TBC surfaces and form calcium-magnesium-alumino-silicate ( CMAS) glass deposits. The molten CMAS glass degrades TBCs, leading to their premature failure. In this context, we have used the concept of optical basicity ( OB) to provide a quantitative chemical basis for the screening of CMAS-resistant TBC compositions, which could also be extended to environmental barrier coatings ( EBCs). By applying OB difference considerations to various major TBC compositions and two types of important CMASs-desert sand and fly ash-the 2 ZrO2· Y2 O3 solid solution (ss) TBC composition, with the potential for high CMAS-resistance, is chosen for this study. Here, we also demonstrate the feasibility of processing of 2ZrO2·Y2O3(ss) air-plasma sprayed ( APS) TBC using commercially developed powders. The resulting TBCs with typical APS microstructures are found to be single-phase cubic fluorite, having a thermal conductivity <0.9 W·(m·K)−1 at elevated temperatures. The accompanying Part II paper presents results from experiments and analyses of high-temperature interactions between 2ZrO2·Y2O3(ss) APS TBC and the two types of CMASs. [ABSTRACT FROM AUTHOR]

To effectively destruct 2-chlorophenol, a representative sterile preservative, nanometer-sized Mn (0.5, 1.0, 3.0 mol %)-incorporated TiO2 powders were synthesized by a solvothermal method. XRD result demonstrated that the Mn ingredients were perfectly inserted into TiO2 framework. The Mn-TiO2 particles exhibited an anatase structure with a particle size of below 20 nm. The absorbance was shifted to the higher wavelength on Mn-TiO2 compared to that of TiO2. Otherwise, the PL intensities which has a close relationship for recombination between holes and electrons significantly decreased on Mn-TiO2. The photodecomposition for 2-chlorophenol in a liquid system was enhanced over Mn-doped TiO2 compared with pure TiO2: 2-chlorophenol of 50 ppm was completely decomposed after 12 h when 1.0 mol % Mn- TiO2 was used. Consequently, the core of this paper is as follows. introducing Mn into TiO2 framework reduced the band-gap, moreover, it played as an electron capture resulted to lower recombination between electrons and holes during photocatalytic reaction for removal of 2-cholophenol. [ABSTRACT FROM AUTHOR]

There is growing demand for practical implementation of lithium–oxygen batteries (LOBs) due to their superior potential for achieving higher energy density than that of conventional lithium‐ion batteries. Although recent studies demonstrate the stable operation of 500 Wh kg−1‐class LOBs, their cycle life remains fancy. For further improving the cycle performance of LOBs, the complicated chemical degradation mechanism in LOBs must be elucidated. In particular, the quantitative contribution of each cell component to degradation phenomenon in LOBs under lean‐electrolyte and high‐areal‐capacity conditions should be clarified. In the present study, the mass balance of the positive‐electrode reaction in a LOB under lean‐electrolyte and high‐areal‐capacity conditions is quantitatively evaluated. The results reveal carbon electrode decomposition to be the critical factor that prevents the prolonged cycling of the LOB. Notably, the carbon electrode decomposition occur during charging at voltages higher than 3.8 V through the electrochemical decomposition of solid‐state side products. The findings of this study highlight the significance of improving the stability of the carbon electrode and/or forming Li2O2, which can decompose at voltages lower than 3.8 V, to realize high‐energy‐density LOBs with long cycle life. [ABSTRACT FROM AUTHOR]

Although microbial communities play an important role in explaining plant litter decomposition rates, whether and how litter chemistry may alter catabolic capacities of soil microbial communities remains poorly studied.During a 1‐year litter decomposition experiment of 12 herbaceous species with contrasting litter chemistry, we examined the effect of plant litter type (roots vs. leaves) and litter chemical traits on the resulting capacity of soil microbial communities to degrade a wide range of carbon substrates of variable complexity (MicroResp™ method).Litter chemistry impacted both the total catabolic activity as well as specific catabolic capacities of microbial communities. In the early stages of litter decomposition total catabolic activity was mainly influenced by the amount of C and N in litter leachates, and litter N, P and Mg, then, later, by lignin concentrations. Some specific catabolic capacities could also be related to litter initial chemistry. Overall, litter trait effects on soil microbial communities decreased over time and the relative importance of traits shifted during the decomposition process.Our results highlight that litter chemistry is a strong driver of catabolic capacities of microbial decomposers and, while its effect fades with time, it remains substantial throughout the litter decomposition process. These long‐lasting effects of litter chemistry suggest a persistent control on microbial catabolic capacities in ecosystems with recurrent litter production. Soil microbial catabolic activities were driven by broadly the same chemical traits across leaf and root litters.Synthesis. Such long‐lasting effects of litter chemistry on catabolic capacities of microbial communities may represent a substantial indirect driver of the decomposition process. Disentangling the relative importance of this overlooked effect of litter chemistry on decomposition represents the next challenge. We argue that such research line should open ground‐breaking perspectives for reconsidering our current understanding of the mechanistic links between litter traits and decomposition rate. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Aluminum titanate (Al2TiO5) is an excellent refractory and thermal shock resistant material due to its relatively low-thermal expansion coefficient and high melting point. However, Al2TiO5 is only thermodynamically stable above 1280°C and undergoes a eutectoid decomposition to α-Al2O3 and TiO2 (rutile) in the temperature range of 900°–1280°C. In this paper, we describe the use of high-temperature neutron diffraction to study the properties of self-recovery in Al2TiO5 when it is annealed at ≥1300°C in air. It is shown that the process of decomposition in Al2TiO5 is reversible and that self-recovery occurs readily when decomposed Al2TiO5 is reheated above 1300°C. It is further shown that the existence of a temperature range (900°–1280°C) in which Al2TiO5 is prone to decomposition can be explained by the competing dominance of self-recovery at ≥1280°C and decomposition at ≤1280°C. [ABSTRACT FROM AUTHOR]

Sucrose (C12H22O11) has been used in low‐activity waste (LAW) melter feeds containing large fractions of nitrates, nitrites, or both because it facilitates foam suppression and denitration. This study focused on the effect of sucrose in LAW feeds on technetium (Tc) and rhenium (Re) retention. The amount of sucrose added in feeds was varied to differentiate the carbon‐to‐nitrogen mole ratio (C/N ratio). The results show that larger sucrose addition (higher C/N ratio) enhances Tc and Re retention. Reducing conditions induced by sucrose decomposition and early chemical reactions between sucrose and NaNO3/NaNO2 are expected to increase Tc and Re retention. However, high sucrose addition decreased sulfur (S) retention slightly because sodium sulfate decomposes in reducing conditions at lower temperature. This early sulfate decomposition can affect Tc and Re retention partly because these species can be soluble in sulfate phases. This correlation indicates that the decrease of sulfate phases in the glass by early decomposition can reduce the solubility of Tc and Re in the sulfate phases, which may increase Tc and Re retention in the glass. In addition, continuous gas evolution and vigorous foaming at the foaming temperature range of 700–900°C may influence Tc and Re retention process interrupting retention or facilitating volatilization. [ABSTRACT FROM AUTHOR]

The design and operation of a low-volume spectroelectrochemical cell for X-ray absorption spectroscopy (XAS) of solutions at room temperature is described. Fluorescence XAS measurements are obtained from samples contained in the void space of a 50 μL reticulated vitreous carbon (sponge) working electrode. Both rapid electrosynthesis and control of the effects of photoreduction are achieved by control over the flow properties of the solution through the working electrode, where a good balance between the rate of consumption of sample and the minimization of decomposition was obtained by pulsing the flow of the solution by 1-2 μL with duty cycle of ~3 s while maintaining a small net flow rate (26-100 μL h-1). The performance of the cell in terms of control of the redox state of the sample and minimization of the effects of photoreduction was demonstrated by XAS measurements of aqueous solutions of the photosensitive FeIII species, [Fe(C2O4)3]3-, together with that of the electrogenerated [Fe(C2O4)3]4- product. The current response from the cell during the collection of XAS spectra provides an independent measure of the stability of the sample of the measurement. The suitability of the approach for the study of small volumes of mM concentrations of protein samples was demonstrated by the measurement of the oxidized and electrochemically reduced forms of cytochrome c. [ABSTRACT FROM AUTHOR]

Chemical degradation in the presence of H2O2 aqueous solution and water states of poly(styrene sulfonic acid) (PSSA) grafted poly(ethylene‐co‐tetrafluoroethylene) polymer electrolyte membranes (ETFE‐PEMs) with grafting degree (GD) of 8.8%–21.1% are investigated using Fourier‐transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), and electrochemical impedance spectroscopy (EIS). The ETFE‐PEMs show the complete detachment at the α‐hydrogen atoms of the whole graft PSSA chains from the ETFE backbones, while their precursor polystyrene‐grafted ETFE films do not. This chemical degradation exhibits independently with GDs and takes place even at very low GD (<10%). Water molecules of the membranes dried at 40°C are not completely de‐absorbed. The remains are partial non‐bonded water molecules, which are assumed to locate within the lamellar amorphous domains (constrained water molecules) of the crystalline phases. These constrained water molecules exist independently with the PSSA groups and do not detach together with them during the degradation. Note that the water molecules remained at 40°C show the additional contribution of 18%–19% to the total water uptake but do not contribute clearly to the conductance. [ABSTRACT FROM AUTHOR]

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Background and Purpose: A peptide bradykinin (BK) B(2) receptor agonist partially resistant to degradation, B-9972, down-regulates this receptor subtype. We have used another recently described non-peptide agonist, compound 47a, as a tool to study further the effects of metabolically more stable and thus persistent, agonists of the BK B(2) receptor on signalling, desensitization and down-regulation of this receptor.Experimental Approach and Key Results: Compound 47a was a partial agonist at the B(2) receptor in the human umbilical vein, where it shared with B-9972 a very slow relaxation on washout, and in HEK 293 cell lines expressing tagged forms [myc, green fluorescent protein (GFP)] of the rabbit B(2) receptor. Compound 47a desensitized the umbilical vein to BK. In the cellular systems, the inactivation-resistant agonists induced [Ca(2+)](i) transients as brief as those of BK but affected other functions with a longer duration than BK [12 h; receptor endocytosis, endosomal beta-arrestin(1/2) translocation, protein kinase C-dependent extracellular signal-regulated kinases (ERK)1/2 phosphorylation and c-Fos expression]. The B(2) receptor-GFP was degraded in cells exposed to B-9972 or compound 47a for 12 h. The non-peptide B(2) receptor antagonist LF 16-0687 prevented all effects of compound 47a, which were also absent in cells lacking recombinant B(2) receptors.Conclusion and Implications: Inactivation-resistant agonists revealed a long-lasting assembly of the agonist-B(2) receptor-beta-arrestin complexes in endosomal structures and induce 'biased signalling' (in terms of activation of ERK and c-Fos) as a function of time. Further, B-9972 and compound 47a, unlike BK, efficiently down-regulated BK B(2) receptors. [ABSTRACT FROM AUTHOR]

Plants return a wide range of carbon (C) substrates to the soil system. The decomposition rate of these substrates is determined by their chemical nature, yet few studies have examined the relative ecological role of specific substrates (i.e., substrate identity) or mixtures of substrates. Carbon substrate identity and diversity may alter soil chemistry and soil community composition, resulting in changes in belowground ecosystem functions such as decomposition and nutrient transfer, creating feedbacks that may affect plant growth and the aboveground community. A laboratory experiment was set up in which eight C substrates of varying chemical complexity were added to a base soil singly, in pairs, fours, or with all eight together every four days over a 92-day period. After 92 days these soils were analyzed for changes in chemistry, microbial community structure, and components of ecosystem functioning. The identity of the added C substrates significantly affected soil chemistry, microbial basal and substrate-induced respiration, and soil microbial community structure measured by either the catabolic response profile (CRP) technique or phospholipid fatty acid composition. These belowground changes strongly affected the ability of the soil microflora to decompose cellulose paper, probably because of differential effects of the C substrates on soil energy supplies and enzyme activities. The addition of C substrates to soils also reduced plant growth compared to the unamended control soil, but less so in soils amended with a tannin than those amended with other substrates. Carbon substrate diversity effects saturated at low diversity levels, tended to have neutral or negative effects on ecosystem functions, and depended strongly on which C substrates were added. It increased CRP compound use but had little effect on other measures of the soil microbial community. Overall, results showed that the chemical nature of C substrates added to soil, and sometimes their diversity, can affect the soil microbial community and soil chemistry, which subsequently affect other ecosystem processes such as decomposition and plant growth. The identity and diversity of substrates that plants add to soil may therefore have important consequences for both above- and belowground ecosystem functions. [ABSTRACT FROM AUTHOR]

Thermal decomposition was the prerequisite and basis for the utilization of magnesite resources. However, the calcination of magnesite was usually accompanied by high energy consumption, which not only caused serious waste of magnesite resources, but also restricted its high value‐added utilization. Therefore, calcination conditions were the key to controlling thermal decomposition process of magnesite. The kinetics of high‐grade magnesite thermal decomposition was elaborated by non‐isothermal thermogravimetric analysis, and meanwhile the effect of heating rate on the magnesite thermal decomposition reaction and morphology of MgO particles were characterized. Both Doyle and Gorbatchev approximate functions were used to simulate the magnesite thermal decomposition process, where the experimental data (correlation coefficient) fitted by the latter could obtain more acceptable kinetic parameters of the magnesite thermal decomposition. The good linear relationship between the activation energy and the pre‐finger factor allowed for a kinetic compensation of the thermal decomposition of magnesite. Furthermore, higher heating rate induced the formation of terraced grains, grain network group, cubic grains, and spherical grains for the samples sintered at 1200°C. The heating rate largely affected the magnesite particle morphology, grain size distribution and activity, and also provided important technical indicators in the actual production of magnesia refractory raw materials. [ABSTRACT FROM AUTHOR]

In this work, acoustic emission was used to investigate the effects of ultraviolet radiation on the mechanical behavior of blends of polypropylene (PP) with ethylene‐octene copolymer (EOC) containing photo stabilizers. Together with traditional techniques, like infrared spectroscopy and microscopy, the data obtained from acoustic emission helped the understanding of the failure caused by photodegradation and the influence of the stabilizing additives. Parameters like number and intensity of hits, released energy and acoustic events were recorded and related to the estate of the degradation and to the stress‐strain behavior. The results confirmed the high sensitivity of PP/EOC blends to ultraviolet and the better performance of stabilized compounds, especially when hindered amine light stabilizers (HALS) were present. Acoustic emission experiments showed that in stabilized samples the crack propagation took place over a larger time interval, releasing more energy during failure and, hence, postponing the final fracture, from a few seconds for the neat blend to more than 500 seconds for the samples with 0.5% HALS. [ABSTRACT FROM AUTHOR]

The aqueous degradation of Eu2+‐activated and Dy3+‐codoped strontium aluminate (SrAl2O4:Eu2+, Dy3+, SA2‐Green) long afterglow phosphors synthesized from solid‐state reaction and coated with nanoscale metal oxide protective layers (≤12 nm) via atomic layer deposition (ALD) is investigated. Uncoated phosphor powders degrade rapidly upon water immersion and lose their green phosphorescence within 48 hours of water exposure. Postmortem investigations reveal hydration and decomposition of the SrAl2O4 phase. ALD of ~10 nm Al2O3 or ~12 nm TiO2 is found to significantly improve the powder's resistance to aqueous degradation. All ALD‐coated powders show minimal structural and chemical degradation and retain phosphoresence after 48 hours of water immersion. This enhanced durability offers a new pathway for applying long afterglow phosphors to outdoor applications like roadway markings or safety signage and for their incorporation into more eco‐friendly waterborne coatings. [ABSTRACT FROM AUTHOR]

Kraft lignin has been widely investigated for blending with a large variety of polymers to produce thermoplastic composites. The ratio of lignin and polymer affects the accessibility of lignin to small molecules and microorganisms, thus influencing the degradation of lignin/polymer composites. In this present work, the stability and degradation of lignin‐polyethylene composites of different compositions in different environments, including water, acidic solution, alkaline solution, and soils have been investigated. The effects of composite composition (with PE content in the range of 30‐80 wt%) and in turn lignin accessibility on the degradation have been elucidated, with some valuable findings disclosed. The degradation/dissolution of lignin creates new void spaces and water fully or partially fills into these void spaces, depending on the specimen size. Because water does not have any interaction with lignin and PE, most of the lignin degradation behaviour does not affect the dimensional size of lignin/PE composites. However, the dissolution of lignin in alkaline solution leads to significant shrinkage of the lignin/PE composite bar, especially in terms of thickness. The lignin degradation behaviour has different effects on the mechanical strength of lignin/PE composites. The composites with low lignin accessibility degrade minimally in all environments, thus retaining most of the mechanical strength. This study provides insight regarding extending/shortening the life cycle of lignin/polymer composites. [ABSTRACT FROM AUTHOR]

Enzyme‐coated polymeric membranes are versatile catalysts for biofuel production and other chemical production from feedstock, like plant biomass. Such bioreactors are more energy efficient than high temperature methods because enzymes catalyze chemical reactions near room temperature. A major challenge in processing plant biomass is the presence of lignin, a complex aromatic polymer that resists chemical breakdown. Therefore, membranes coated with enzymes such as laccase that can degrade lignin are sought for energy extraction systems. We present an experimental study on optimizing an enzyme‐based membrane bioreactor and investigate the tradeoff between high flow rate and short dwell time in the active region. In this work, zero flow rate voltammetry experiments confirm the electrochemical activity of Trametes versicolor laccase on conductive polymer electrodes, and a flow‐through spectroscopy device with laccase‐coated porous nylon membranes is used with a colorimetric laccase activity indicator to measure the catalysis rate and percent conversion as a function of reactant flow rate. Membrane porosity before and after laccase coating is verified with electron microscopy. [ABSTRACT FROM AUTHOR]

This article provides a summary of the paper "Tropical Freshwater Ecology" presented by R. S. A. Beauchamp at the Spring Meeting of the Tropical Group of the British Ecological Society held in London, England, on April 24, 1969. The paper examines the presence of vast quantities of organic matter deposited in Lake Victoria in Uganda. It notes that the material does not decompose readily and it was found in large quantities only in areas of the lake that were less than 60 meters deep. It assumes that the productivity of the lake is controlled to a large extent by the numbers of Tilapia present.

The degradation behavior of poly(lactic‐co‐glycolic acid) (PLGA) is important for its application as a biomaterial. In this work, the influence of nano‐hydroxyapatite (nano‐HA) on the degradation behavior of PLGA matrix was studied. PLGA‐based in situ forming system containing nano‐HA was prepared using the immersion precipitation method and the polymer hydrolysis was investigated in a phosphate buffer (pH 7.4) at 37°C. The pH values in the testing medium were evaluated to quantify the degradation process. Gel permeation chromatography and scanning electron microscopy techniques were employed to monitor changing of the weight‐average molecular weight (MW) and the body structures of PLGA matrices, respectively. To model the MW changes, a first‐order degradation model was employed. The formed PLGA matrices had different porosities that effected water penetration into the matrices following the hydrolysis process. The obtained degradation rate constant using a mathematical model for PLGA matrices with different nano‐HA content was about from 2.5 to 4.5 times lower than neat PLGA matrix. POLYM. ENG. SCI., 59:1028–1035, 2019. © 2019 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

SF6 has been widely used as an insulating and arc extinguishing medium in electric power equipments. Detection of gas decomposition products is an important means for condition monitoring and fault diagnosis. Trace H2O and O2 have a significant influence on the species and concentrations of SF6 decomposition products. It is important to explore the influence mechanism of trace H2O and O2 on SF6 decomposition products under arcing conditions. A series of SF6 decomposition tests were carried out on a 40.5kV SF6 circuit breaker, and a gas chromatograph and an electrochemical sensor were used to measure decomposed components. First, the H2O content remained constant, and the O2 content and arcing energy changed in the tests. It has been found that the decomposition products of SF6 are SOF2, SO2, CO, CO2, CF4, C2F6 and C3F8. Then, the O2 content remained constant, and the H2O content changed. The decomposition products are mainly SOF2, SO2, CO and CO2. Concentrations of all these decomposition products increase first and then tend to be stable slowly over time, but change differently with the increase of H2O and O2 contents, because H2O and O2 play different roles in the formation process of each decomposition characteristic components. [ABSTRACT FROM AUTHOR]

Azodicarbonamide (ADCA) is a well‐known chemical blowing agent used in the fabrication of polyolefin foams which decomposes into gases at temperatures above the melting temperature of the polymer. In these polymer foams, the polymer is usually crosslinked before or during the foaming process to increase its viscosity and make it capable of supporting the pressure of the gas during foaming. This crosslinking process allows producing low‐density foams with homogeneous cellular structures. A typical procedure to crosslink the polymer is to irradiate it using a high energy‐electron beam. When ADCA is incorporated into the polymer before the irradiation process, it is also exposed to the high energy electron beam. However, the effect of the irradiation on the decomposition process of ADCA has not been explored yet. In this research, it has been found that there is a reduction of the thermal decomposition temperature of ADCA when this material is electron irradiated with different doses ranging from 25 to 150 kGy, being this reduction higher when the irradiation dose is increased. It has also been found, that the reduction of the decomposition temperature is due to a modification of the lattice parameters of the crystalline structure of ADCA. POLYM. ENG. SCI., 59:791–798, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

This Review presents the current status of the noble gas (Ng)‐noble metal chemistry, which began in 1977 with the detection of AuNe+ through mass spectroscopy and then grew from 2000 onwards; currently, the field is in a somewhat matured state. On one side, modern quantum chemistry is very effective in providing important insights into the structure, stability, and barrier for the decomposition of Ng compounds and, as a result, a plethora of viable Ng compounds have been predicted. On the other hand. experimental achievement also goes beyond microscopic detection and characterization through spectroscopic techniques and crystal structures at ambient temperature; for example, (AuXe4)2+(Sb2F11−)2 have also been obtained. The bonding between two noble elements of the periodic table can even reach the covalent limit. The relativistic effect makes gold a very special candidate to form a strong bond with Ng in comparison to copper and silver. Insertion compounds, which are metastable in nature, depending on their kinetic stability, display an even more fascinating bonding situation. The degree of covalency in Ng–M (M=noble metal) bonds of insertion compounds is far larger than that in non‐insertion compounds. In fact, in MNgCN (M=Cu, Ag, Au) molecules, the M−Ng and Ng−C bonds might be represented as classical 2c–2e σ bonds. Therefore, noble metals, particularly gold, provide the opportunity for experimental chemists to obtain sufficiently stable complexes with Ng at room temperature in order to characterize them by using experimental techniques and, with the intriguing bonding situation, to explore them with various computational tools from a theoretical perspective. This field is relatively young and, in the coming years, a lot of advancement is expected experimentally as well as theoretically. The test of time: The initial difficulties are in making noble‐gas compounds long after the discovery of a noble gas and, eventually, the start of noble‐gas chemistry in 1962 are described in brief. Then, the bonding between two nobles in the periodic table, that is, a noble metal and a noble gas, is summarized in chronological order. This highlights the versatile aspect of this relatively young but very promising field. The large‐scale synthesis of AuXe42+(Sb2F11−)2 is a landmark discovery in this field. [ABSTRACT FROM AUTHOR]

The Dispase autolysis‐inducing protein (DAIP) is produced by Streptomyces mobaraensis to disarm neutral metalloproteases by decomposition. The absence of a catalytic protease domain led to the assumption that the seven‐bladed β‐propeller protein DAIP causes structural modifications, thereby triggering autolysis. Determination of protein complexes consisting of DAIP and thermolysin or DAIP and a nonfunctional E138A bacillolysin variant supported this postulation. Protein twisting was indicated by DAIP‐mediated inhibition of thermolysin while bacillolysin underwent immediate autolysis under the same conditions. Interestingly, an increase in SYPRO orange fluorescence allowed tracking of the fast degradation process. Similarly rapid autolysis of thermolysin mediated by DAIP was only observed upon the addition of amphiphilic compounds, which probably amplify the induced structural changes. DAIP further caused degradation of FITC‐labeled E138A bacillolysin by trypsin, as monitored by a linear decrease in fluorescence polarization. The kinetic model, calculated from the obtained data, suggested a three‐step mechanism defined by (a) fast DAIP–metalloprotease complex formation, (b) slower DAIP‐mediated protein twisting, and (c) fragmentation. These results were substantiated by crystallized DAIP attached to a C‐terminal helix fragment of thermolysin. Structural superposition of the complex with thermolysin is indicative of a conformational change upon binding to DAIP. Importantly, the majority of metalloproteases, also including homologs from various pathogens, are highly conserved at the autolysis‐prone peptide bonds, suggesting their susceptibility to DAIP‐mediated decomposition, which may offer opportunities for pharmaceutical applications. Databases: The atomic coordinates and structure factors (PDB ID: 6FHP) have been deposited in the Protein Data Bank (http://www.pdb.org/). Enzymes: Aureolysin, EC 3.4.24.29; bacillolysin (Dispase, Gentlyase), EC 3.4.24.28; lasB (elastase), EC 3.4.24.4; subtilisin, EC 3.4.21.62; thermolysin, EC 3.4.24.27; transglutaminase, EC 2.3.2.13; trypsin, EC 3.4.21.4; vibriolysin (hemagglutinin(HA)/protease), EC 3.4.24.25. The Dispase autolysis‐inducing protein (DAIP) from Streptomyces mobaraensis adopts a seven‐bladed β‐propeller fold mediating metalloproteases self‐degradation. The present study now reveals strong attraction of bacillolysin and thermolysin by DAIP, complex formation, and protein twisting followed by fragmentation as indicated by SYPRO orange and FITC‐labeled bacillolysin. The biochemical data are completed by crystallized DAIP in complex with a C‐terminal thermolysin fragment. [ABSTRACT FROM AUTHOR]

Among the industrial effluents presenting constraints to traditional biological treatments, those from textile industries are of particular concern. Wet air oxidation is an effective process that significantly increases biodegradability of the treated effluent. In this study, the advantage of this process was tested for the treatment of acid orange 7, a dye molecule used as a model textile effluent. Different experimental conditions of temperature (200 to 300 °C) and duration of treatment were used to determine its degradation yield during the wet air oxidation process, at a total pressure of 30 MPa. All these conditions led to complete degradation of acid orange 7, but residual Total Organic Carbon always remained. Oxidation byproducts were identified by the means of GC and HPLC analyses. Acetic acid remains the major compound not oxidized. These experiments resulted in the proposal of a reaction scheme associated with kinetic constants. Finally, the optimal conditions for the improvement of the biodegradability of the effluent were determined. This wet air oxidation process could then be coupled with a biological treatment to obtain an overall degradation meeting the criteria for release into the environment. The colour of the effluent changes with oxidation duration: the initial orange colour changes to black, followed by different colours with less intensity. [ABSTRACT FROM AUTHOR]

Abstract: To obtain a deeper understanding of the process involved in the synthesis of N‐nitrodiethanolamine dinitrate (DINA), in this work we carried out systematic studies on the transformation and stability of the N‐nitration liquid and DINA. The thermal decomposition processes and dynamic characteristics for both the N‐nitration liquid and DINA were carried out by thermal analysis methods and the mechanism for the decrease of stability of the N‐nitration liquid was proposed according to experimental results. Mechanical stimulation of the N‐nitration liquid and DINA were also studied by friction and impact sensitivity testing. The experimental results showed that the N‐nitration liquid is highly sensitive to temperature and can decompose easily when the reaction temperature increases. However, mechanical sensitivity of the N‐nitration was demonstrated to be much lower than that of DINA. Therefore, precise thermal control is the key factor to ensure safety during the preparation of DINA. [ABSTRACT FROM AUTHOR]

BiIO4/Bi2O2(BO2OH) heterostructure is successfully synthesised by the method of one-step hydrothermal treatment. Characterisation of BiIO4/Bi2O2(BO2OH) heterostructure is performed by X-ray diffraction, scanning electron microscope, transmission electron microscopy and ultraviolet (UV)–visible diffuse reflectance. The photocatalytic activity is measured by the decomposition of rhodamine B under UV light irradiation. Compared with Bi2O2(BO2OH), BiIO4 and P25, it is noted that 35 wt% BiIO4/Bi2O2(BO2OH) exhibits better performance on degradation. The type-II band alignment of the heterostructure and the decreased recombination rate of electron–hole pairs contribute to this significant enhancement of decomposition of organic contaminations. [ABSTRACT FROM AUTHOR]

UV-based technologies have been proposed for the treatment of wastewater containing bisphenol A (BPA), a toxic, endocrine-disruptor pollutant. Nevertheless, the evaluation of the role of process variables through experimental design has not been previously addressed. In this study, the effects of BPA and H2O2 initial concentrations, and specific photon emission rate ( EP,0) on BPA degradation by the UV and UV/H2O2 processes were investigated, using the Doehlert design and response surface analysis. The experiments were performed in a tubular reactor equipped with a 254-nm UV lamp, for [H2O2]0 and EP,0 in the ranges 1.6-9.6 mmol · L−1 and 0.87 × 1018-3.6 × 1018 photons · L−1 · s−1, respectively. Photolysis ([BPA]0 = 10-50 mg · L−1) was shown to be inefficient for BPA degradation and mineralization, with pollutant removals lower than 55 %. The specific BPA photolysis rate and BPA removal decreased with increasing [BPA]0. In contrast, all the UV/H2O2 experiments ([BPA]0 = 50 mg · L−1) resulted in total BPA degradation after 60 min of irradiation. In this case, the best conditions were [H2O2]0 = 7.6 mmol · L−1 and Ep,0 = 3.6 × 1018 photons · L−1 · s−1, achieving the highest BPA degradation rate and removal after 15 min, and the second highest TOC removal after 180 min. In most experiments less than 75 % TOC removal was achieved, with 95 % mineralization observed solely for the highest [H2O2]0 and EP,0. In any case, the residual toxicity and endocrine activity of treated solutions must be determined, in order to prove the applicability of the UV/H2O2 process for real water and wastewater treatment. [ABSTRACT FROM AUTHOR]

Time series analysis is an essential method for decomposing the influences of density and exogenous factors such as weather and climate on population regulation. However, there has been little work focused on understanding how well commonly collected data can reconstruct the effects of environmental factors on population dynamics. We show that, analogous to similar scale issues in spatial data analysis, coarsely sampled temporal data can fail to detect covariate effects when interactions occur on timescales that are fast relative to the survey period. We propose a method for modeling mismatched time series data that couples high-resolution environmental data to low-resolution abundance data. We illustrate our approach with simulations and by applying it to Florida's southern Snail kite population. Our simulation results show that our method can reliably detect linear environmental effects and that detecting nonlinear effects requires high-resolution covariate data even when the population turnover rate is slow. In the Snail kite analysis, our approach performed among the best in a suite of previously used environmental covariates explaining Snail kite dynamics and was able to detect a potential phenological shift in the environmental dependence of Snail kites. Our work provides a statistical framework for reliably detecting population-environment interactions from coarsely surveyed time series. An important implication of this work is that the low predictability of animal population growth by weather variables found in previous studies may be due, in part, to how these data are utilized as covariates. [ABSTRACT FROM AUTHOR]

Animal defecation, or egestion, is a pronounced transformation of organic matter in many ecosystems. However, because egesta have been presumed recalcitrant and low nutrient, their significance and variability as an animal nutrient flux in aquatic settings - especially relative to mineralization via excretion - are poorly known., We compared carbon (C), nitrogen (N) and phosphorus (P) dynamics over short- to long-term (up to 107 days) microbial decomposition of egesta from the aquatic shredders Allocapnia spp., Lirceus spp. and Tipula spp. fed low- or high-P content Platanus occidentalis litter to investigate roles of egesta in aquatic nutrient dynamics., Tipula produced N and P deplete egesta of higher N : P compared to Lirceus and Allocapnia, and high-P diets increased egesta P content compared to low-P diets. Despite measurable C losses to decomposition, these differences in nutrient content persisted through decomposition, showing diet and species control both immediate and long-term properties of egested particles., Egesta switched between uptake and release of dissolved phosphorus and ammonium during decomposition, and exhibited consistent net N uptake as nitrate-nitrite. Across species and diets, lower N : P egesta tended to exhibit greater uptake of dissolved inorganic N, suggesting P enrichment of egesta drove stronger dissolved N demand by decomposer microbes., Shredder egesta exhibit stable nutrient contents long term and, counter to assumptions that they are negligible or minor net sources, can be strong, extended sinks of dissolved inorganic nutrients. Future studies should consider contrasts between animal nutrient fluxes as excretion, which facilitates nutrient recycling via mineralization, vs. egestion, which slows nutrient recycling via organic nutrient repackaging and can create sinks of dissolved nutrients., A is available for this article. [ABSTRACT FROM AUTHOR]

Contents958I.958II.959III.960IV.962V.962962References963 Summary: Proteases can either digest target proteins or perform the so‐called ‘limited proteolysis’ by cleaving polypeptide chains at specific site(s). Autophagy and the ubiquitin–proteasome system (UPS) are two main mechanisms carrying out digestive proteolysis. While the net outcome of digestive proteolysis is the loss of function of protein substrates, limited proteolysis can additionally lead to gain or switch of function. Recent evidence of crosstalk between autophagy, UPS and limited proteolysis indicates that these pathways are parts of the same proteolytic nexus. Here, we focus on three emerging themes within this area: limited proteolysis as a mechanism modulating autophagy; interplay between autophagy and UPS, including autophagic degradation of proteasomes (proteophagy); and specificity of protein degradation during bulk autophagy. [ABSTRACT FROM AUTHOR]

Isotactic polypropylene (iPP) films of 25 μm thickness were subjected to gamma-ray irradiation for different doses (30, 60, 90 and 100 kGy) at ambient atmosphere and both molecular modifications and surface properties have been investigated by Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM), respectively. The occurrence of the oxidation process is identified and quantified by the FTIR. In addition, it is found that the carbonyl index increases with the absorbed dose which confirms that the irradiation process induces the diffusion of the oxygen into the iPP matrix. The AFM image (for virgin and higher dose irradiated samples) showed a dramatic change in the surface topography. The gamma radiation induces the formation of the nanostructured iPP surface. The roughness of the polymer surface, measured by AFM, increases after gamma irradiation. These results revealed that the oxidative degradation may be correlated with the morphological properties. [ABSTRACT FROM AUTHOR]

This study examined the thermo-oxidative degradation of stigmasterol fatty acids esters. Stigmasterol stearate, oleate, linoleate and linolenate were synthesized by chemical esterification and their purity evaluated by H-NMR and GC-MS. The degradation of stigmasterol esters was examined after heating them at 60 and 180 °C for 1, 2, 4, 8 and 12 h. It was established that stigmasterol esters were prone to thermo-oxidative degradation, with time and temperature affecting the degree of degradation. The unsaturation of fatty acids affected the rate of stigmasteryl ester degradation. The kinetics of StS and StO degradation were similar and the additional double bonds in StL and StLn resulted in their faster decomposition. The esters degraded faster at 180 than at 60 °C. The sterol and fatty acid molecules degraded at different rates, such that the fatty acid moiety deteriorated faster than the sterol at both temperatures, independent of the time of heating and the level of unsaturation. [ABSTRACT FROM AUTHOR]

Reaction-bonded silicon carbide ( RBSC) was prepared by ceramic injection molding ( CIM) technique with feedstocks containing silicon carbide (SiC), a wax-based organic system and different amounts of carbon black. As a critical effect of the reaction sintering process, carbon was introduced from the carbon black and the decomposition product of the organic polymers, respectively. This study described the influence of carbon content on the mixing and injection process firstly and then emphasized the debinding process since it played a large role in the process of the pyrolysis of organic. Results indicated that the preferable thermal debinding was performed in N2 and the optimal performance was obtained for RBSC with 7 wt.% of carbon black, with the density of 2.98 g/cm3, apparent porosity of 0.24%, bending strength of 301.59 MPa and fracture toughness of 4.18 MPa·m1/2. [ABSTRACT FROM AUTHOR]

In this study, sodium hydroxide was employed to decompose animal gelatin. The gelatin hydrolysate was then reacted with polyisobutenyl succinic anhydride, containing a hydrophilic substituent, to produce a series of gelatin derivatives (GD) that featured both hydrophobic and hydrophilic groups, thereby displaying the behavior of surfactants. The structures of the synthesized surfactants were examined using infrared spectroscopy and proton nuclear magnetic resonance spectroscopy; the basic surface properties, including surface tension, contact angle, emulsifying capacity, and foamability, were also determined. The synthesized GD surfactants had superior surface activities. In addition, the surface activities of the GD. increased upon increasing the length of the hydrophobic unit and the molecular weight. These GD exhibited good foamability and emulsifying capacity, with the GD containing PBMA 320 possessing the greatest surface activity. [ABSTRACT FROM AUTHOR]

A novel TiO2/MoS2 composite photocatalyst with high visible-light activity was prepared via a one-step hydrothermal process using titaniumtetrachloride (TiCl4) as a titanium resource and bulk MoS2 as a direct photosensitizer. The photocatalytic degradation of methyl orange (MO) in aqueous suspension was employed to evaluate the visible light activity of the as-prepared composite photocatalyst with a xenon lamp as simulated solar irradiation. The chemical composition, optical properties, morphology, structure, and thermal stability of the composite photocatalysts were characterized using XPS, UV-vis, FS, SEM, XRD, and TGA. The as-prepared photocatalysts exhibited enhanced photocatalytic activity from the experiment on the degradation of methyl orange, compared to the performance of commercial titania (Degussa P25). The degradation rate of MO can reach over 90 % in 10 min when the molar ratio of molybdenum disulfide (MoS2) to titanium dioxide (TiO2) is 0.8:50 and the mass concentration of the TiO2/MoS2 composite photocatalyst is 400 mg/L. In this research, a new fabrication mode of TiO2/MoS2/TiO2 was applied for fabricating new hybridized structures of nano-TiO2/MoS2 by using bulk MoS2 as a direct photosensitizer, which changed the energy levels of the conduction band of MoS2 and strongly promoted interparticle electron transfer. In addition, this hybridization structure was believed to have a synergistic effect in the process of photocatalytic oxidation owing to increasing the degree of charge carrier separation, which effectively reduced recombination and improved the photocatalytic activity of the TiO2/MoS2 composite photocatalyst. [ABSTRACT FROM AUTHOR]

Boehmite synthesized through a sol-gel route from a nonconventional raw material, as an aluminum waste, was calcined at temperatures between 500 and 1500°C. Quantification of crystalline phases was performed by the Rietveld refinement of the XRD patterns. γ-Al2O3 is formed at 500°C, and up to 1000°C, is the dominant phase. At temperatures ranging from 1000 to 1400°C, it was observed the appearance of a four-phase region. The complete transformation into α-Al2O3 lasts until 12 h at 1400°C or at higher temperatures. The presence of an amorphous phase in calcined samples was confined by direct comparison with a standard of pure α-Al2O3. [ABSTRACT FROM AUTHOR]

We proposed a model to study the resistance degradation behavior of ferroelectric oxides in the presence of ferroelectric spontaneous polarization by combining the phase-field model of ferroelectric domains and nonlinear diffusion equations for ionic/electronic transport. We took into account the nonperiodic boundary conditions for solving the electrochemical transport equations and Ginzburg-Landau equations using the Chebyshev collocation algorithm. We considered a single domain structure relative to a thin film BaTiO3 single crystal orientated to the normal of the electrode plates (Ni) in a single parallel plate capacitor configuration. The capacitor was subjected to a dc bias of 0.5 V either along the polarization direction or opposite to the polarization direction at 25°C. It is shown that the polarization bound charges at the metal/ferroelectric interface play an important role in charge carrier transport and leakage current evolution in BaTiO3 capacitor. [ABSTRACT FROM AUTHOR]

The studies on design and synthesis of new monocyclic β-lactam esters 4(R/S)-(1'-methoxycarbonylpropyl-2'(R/S)-thio)-3(R)-phenylacetamidoazetidin-2-one (3a) and 4(R/S)-(1'-methoxycarbonyl-2'-methyl-propyl-2'-thio)-3(R)-phenylacetamidoazetidin-2-one (3b) were described. Compounds 3a and 3b were specifically designed to retain all penicillin substructures except the bicyclic system, which would be conceived by cleaving the C(3)--N(4) bond of penicillin G. Compounds 3a and 3b are of particular interest in the context of the structural elucidation of monocyclic β-lactams originated from penicillin. Key intermediates, β-mercapto esters 6a and 6b, were synthesized from conjugate acids 4a and 4b using three-step synthetic sequences, respectively, and 4(S)-acetoxy-3(S)-phenylacetamidoazetidin-2-one (7) was obtained from the degradation of penicillin G. Reactions of 6a and 6b with 7, thus obtained, provided the target compounds 3a and 3b, respectively. [ABSTRACT FROM AUTHOR]

The adsorption and decomposition of trimethylene oxide (C3H6O) molecule on the Al(111) surface were investigated by the generalized gradient approximation (GGA) of density functional theory (DFT). The calculations employed a supercell (6 x 6 x 3) slab model and three-dimensional periodic boundary conditions. The strong attractive forces between C3H6O molecule and Al atoms induce the C-O bond breaking of the ring C3H6O molecule. Subsequently, the dissociated radical fragments of C2H6O molecule oxidize the Al surface. The largest adsorption energy is about -260.0 kJ/mol in V3, V4 and P2, resulting a ring break at the C-O bond. We also investigated the decomposition mechanism of C3H6O molecules on the Al(111) surface. The activation energies (Ea) for the dissociations V3, V4 and P2 are 133.3, 166.8 and 174.0 kJ/mol, respectively. The hcp site is the most reactive position for C3H6O decomposing. [ABSTRACT FROM AUTHOR]

Under the current paradigm, organic matter decomposition and nutrient cycling rates are a function of the imbalance between substrate and microbial biomass stoichiometry. Challenging this view, we demonstrate that in an individual-based model, microbial community dynamics alter relative C and N limitation during litter decomposition, leading to a system behaviour not predictable from stoichiometric theory alone. Rather, the dynamics of interacting functional groups lead to an adaptation at the community level, which accelerates nitrogen recycling in litter with high initial C : N ratios and thus alleviates microbial N limitation. This mechanism allows microbial decomposers to overcome large imbalances between resource and biomass stoichiometry without the need to decrease carbon use efficiency ( CUE), which is in contrast to predictions of traditional stoichiometric mass balance equations. We conclude that identifying and implementing microbial community-driven mechanisms in biogeochemical models are necessary for accurately predicting terrestrial C fluxes in response to changing environmental conditions. [ABSTRACT FROM AUTHOR]

Graphitic g-C3N4-WO3 composite was synthesized simply by decomposing melamine in the presence of WO3 at 500°C. The obtained material was characterized by XRD, SEM, IR and XPS. The results showed that the as-prepared composite exhibits orthorhombic WO3 phase coated by g-C3N4 and the g-C3N4 decomposed completely with N-doped WO3 remaining at elevated calcination temperatures. The photocatalytic activity of the composite was evaluated by the photodegradation of methylene blue under visible light. An enhancement in photocatalytic activity for the graphitic g-C3N4-WO3 composite compared to the conventional nitrogendoped WO3 was observed, which can be attributed to the presence of g-C3N4 in the material. [ABSTRACT FROM AUTHOR]

This article discusses the interrelation between formulation, processing, and properties of biocomposites composed of a bioplastic reinforced with wood fibers. Polylactide (PLA) and polylactide/thermoplastic starch blends (PLA/TPS) were used as polymeric matrices. Two grades of PLA, an amorphous and a semicrystalline one, were studied. TPS content in the PLA/TPS blends was set at 30, 50, and 70 wt%. Two types of wood fiber were selected, a hardwood (HW) and a softwood (SW), to investigate the effect of the fiber type on the biocomposite properties. Finally, the impact of different additives on biocomposite properties was studied with the purpose to enhance the bioplastic/wood fiber adhesion and, therefore, the final mechanical performance. The biocomposites containing 30 wt% of wood fibers were obtained by twin-screw extrusion. The properties of the biocomposites are described in terms of morphology, thermal, rheological, and mechanical properties. Furthermore, the biocomposites were tested for humidity and water absorption and biodegradability. An almost 100% increase in elastic modulus and 25% in tensile strength were observed for PLA/wood fiber biocomposite with the best compatibilization strategy used. The presence of the TPS in the biocomposites at 30 and 50 wt% maintained the tensile strength higher or at least equal as for the virgin PLA. These superior tensile results were due to the inherent affinity between the matrices and wood fibers improved by the addition of a combination of coupling and a branching agent. In addition to their outstanding mechanical performance, the biocomposites showed high biodegradation within 60 days. POLYM. ENG. SCI., 54:1325-1340, 2014. © Her Majesty the Queen in Right of Canada 2013 [ABSTRACT FROM AUTHOR]