Multi-objective model auto-calibration and reduced parameterization: Exploiting gradient-based optimization tool for a hydrologic model

Multi-objective model optimization methods have been extensively studied based on evolutionary algorithms, but less on gradient-based algorithms. This study demonstrates a framework for multi-objective model calibration/optimization using gradient-based optimization tools. Model-independent software Parameter ESTimation (PEST) was used to auto-calibrate ISWAT, a modified version of the distributed hydrologic model Soil and Water Assessment Tool (SWAT2005), in the Shenandoah River watershed. The time-series processor TSPROC was used to combine multiple objectives into the auto-calibration process. Two sets of roughness coefficients for main channels, one assigned and calibrated according on soil types and one determined via empirical equations, were examined for stream discharge simulation. Five different weighting alternatives were investigated for their effects on ISWAT calibrations. Results showed that using Manning's roughness coefficients obtained from empirical equations improves simulation results and calibration efficiency. Applying a two-step weighting alternative to different observation groups would provide the best calibration results.     

Using QuickBird imagery and a production efficiency model to improve crop yield estimation in the semi-arid hilly Loess Plateau,China

Crop yield is a key element in rural development and an indicator of national food security. A method that could estimate crop yield over large hilly areas would be highly desirable. Methods including high spatial resolution satellite imagery have the potential to achieve this objective. This paper describes a method of integrating QuickBird imagery with a production efficiency model (PEM) to estimate crop yield in Zhonglianchuan, a hilly area on Loess Plateau, China. In the PEM model, crop yield is a function of the photosynthetic active radiation (PAR), fraction of absorbed photosynthetically active radiation (f_APAR) and light-use efficiency (LUE). Based on the high spatial resolution QuickBird imagery, a land cover classification is used to attribute a class-specific LUE. The f_APAR is related to spectral vegetation indices (SVI), which can be derived from the satellite images. The LUE, f_APAR and incident PAR data were combined to estimate the crop yield. Farmer-reported crop yield data in 80 representative plots were used to validate the model output. The results indicated QuickBird imagery can improve the accuracy of predicted results relative to the Landsat TM image. The predicted yield approximated well with the data reported by the farmers (r² = 0.86; n = 80). The spatial distributions of crop yield derived here also offers valuable information to manage agricultural production and understand ecosystem functioning.     

The effects of PVP surfactant in the direct and indirect hydrothermal synthesis processes of ceria nanostructures

CeO₂ nanostructures with completely different morphologies were successfully prepared using the same cerium source and mineralizer through the direct and indirect hydrothermal methods with different introducing strategies of PVP surfactant. The CeO₂ nanostructures tend to form the morphologies of nano-flowers and nano-cubes through the indirect and direct hydrothermal methods, respectively. X-ray diffraction (XRD) analyses revealed that both as-prepared nanostructures are composed of CeO₂ with a standard fluorite structure. The different synthesis mechanisms and corresponding chemical evolutions of the as-prepared CeO₂ nanostructures are discussed based on the different introducing strategies of PVP surfactant in the direct and indirect hydrothermal processes. Investigation of the UV-shielding ability of both CeO₂ nanostructures suggested that the UV absorbance of the nano-flowers is much higher than that of the nano-cubes.     

Heteroatom-doped carbon nanorods with improved electrocatalytic activity toward oxygen reduction in an acidic medium

High-performance heteroatom-doped carbon catalysts with large surface areas were prepared by pyrolyzing nanorod precursors that had been synthesized by polymerizing a mixture of aniline (An) and β-naphthalene sulfonic acid (NSA). The catalysts were characterized by scanning and transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N₂ adsorption/desorption isotherms, and elemental analysis. We intensively investigated how the catalysts’ structure and catalytic performance were affected by (i) the ratio of NSA to An and (ii) the addition of Fe. The catalysts retained their nanorod morphology after pyrolysis. The optimal NSA/An ratio was 3/2 and the optimal Fe content was 3 wt%. The catalysts showed excellent activity toward oxygen reduction in an acidic medium, with the onset potential, half-wave potential, and limiting current density values reaching 0.86, 0.73 V (vs. reversible hydrogen electrode), and 5.28 mA cm⁻², respectively. We suggest that the catalysts’ high performance may be due to the co-doping effects of nitrogen, sulfur, and iron, as well as the large surface area created by the nanorod structures.     

Facial synthesis of dandelion-like g-C3N4/Ag with high performance of photocatalytic hydrogen production

Nowadays, energy shortage is one of the major problems in the world. Photocatalytic hydrogen production is a new type of energy technology with good application prospect. As a new type of photocatalytic semiconductor material, g-C₃N₄ has attracted much attention as a photocatalyst. By ultrasonic treatment of a mixed solution of g-C₃N₄ and bovine serum albumin, followed by adding a certain amount of silver nitrate solution and then directly hydrothermal treatment, a special dandelion-like g-C₃N₄/Ag (D-g-C₃N₄/Ag) was prepared. The scanning electronic microscopy, transmission electronic microscopy, X-ray diffraction, Fourier transform infrared, fluorescence and physicochemical adsorption methods were used to characterize the morphology and structure of D-g-C₃N₄/Ag. In addition, the photocatalytic H₂ production of D-g-C₃N₄/Ag with different Ag loadings or in different sacrificial agents and different pH conditions were investigated. The results indicated that when triethanolamine was used as sacrificial agent, photocatalytic hydrogen efficiency was the best, and the rate of photocatalytic hydrogen production reached 862 μmol g⁻¹ h^{− 1} as the Ag loading was 4%.     

Development of single nucleotide polymorphism markers from ESTs for discrimination between domestic and imported manila clams,Ruditapes philippinarum

Large amounts of the manila clam, Ruditapes philippinarum, have been imported from Dalian (China) recently to meet the increasing demand in Korea. To ensure the quality and safety of the domestic marine product, it is necessary to be able to distinguish between domestic manila clams and clams that are imported from Dalian, China. We developed expressed sequence tags (ESTs)-derived single nucleotide polymorphism markers using 454 pyrosequencing. A total of 780,000 ESTs were assembled, and 49,540 putative SNPs were identified from 46,405 contigs. Twenty-one polymorphic SNPs from 11 primers were finally selected as diagnostic markers. Genotype analysis showed that 21 SNP markers had the opposite alleles (transitions or transversions) between domestic and imported samples, which were useful for distinguishing clam origins. The GENECLASS 2.0 program was used to estimate the ability of the markers in the discrimination between domestic and imported populations. The 21 SNP markers had 98.96% ability to discriminate domestic manila clams and 100% ability to identify those imported. These markers could be useful for discriminating between domestic and imported manila clams and can contribute to the prevention of falsified labeling of this species.     

Aflatoxin B1 degradation by culture and lysate of a Pontibacter specie

The presence of aflatoxin B₁ (AFB₁) along the food chain poses a significant threat, thus propelling the need for an effective approach to control it. This study was therefore, aimed at investigating AFB₁ degradation of liquid cultures and lysates of an isolated Pontibacter sp. (VGF1). Liquid cultures, lysed bacterial cells in the absence (uninhibited lysates) and presence of protease inhibitors (protease inhibited lysates) were respectively incubated with AFB₁ for 3, 6, 12, 24 and 48 h. AFB₁ degradation was monitored during this period on high performance liquid chromatography (HPLC) and results obtained revealed that after 6 h of incubation, the protease inhibited (PI) lysates yielded a 65% AFB₁ degradation, whereas after 12 h, no residual AFB₁ was detected. Conversely, after 48 h of incubation, a significantly (p≤0.05) lower AFB₁ degradation of 50 and 36% by the liquid culture and uninhibited lysate, respectively, were noted. It was further confirmed that the degradation mechanism was enzymatic. Data from cytotoxicity studies against human lymphocytes further demonstrated that extracts of biotransformed AFB₁ were less toxic when compared to that of AFB₁. Findings from this study have demonstrated an alternative approach for the decontamination and biocontrol of AFB₁ in various agricultural commodities.     

Biological abatement of inhibitors in rice hull hydrolyzate and fermentation to ethanol using conventional and engineered microbes

Microbial inhibitors arise from lignin, hemicellulose, and degraded sugar during pretreatment of lignocellulosic biomass. The fungus Coniochaeta ligniaria NRRL30616 has native ability to metabolize a number of these compounds, including furan and aromatic aldehydes known to act as inhibitors toward relevant fermenting microbes. In this study, C. ligniaria was used to metabolize and remove inhibitory compounds from pretreated rice hulls, which comprise a readily available agricultural residue rich in glucose (0.32–0.33 g glucan/g hulls) and xylose (0.15–0.19 g xylan/g hulls). Samples were dilute-acid pretreated and subjected to bioabatement of inhibitors by C. ligniaria. The bioabated rice hull hemicellulose hydrolyzates were then utilized for ethanol fermentations. In bioabated liquors, glucose was converted to 0.58% (w/v) ethanol by Saccharomyces cerevisiae D5a at 100% of theoretical yield, while fermentations of unabated hydrolyzates either failed to exit lag phase or had reduced ethanol yield (80% of theoretical). In fermentations using ethanologens engineered for conversion of pentoses, bioabatement of hydrolyzates similarly improved fermentations. Fermentation of xylose and arabinose by ethanologenic Escherichia coli FBR5 yielded 2.25% and 0.05% (w/v) ethanol from bioabated and unabated samples, respectively. Fermentations using S. cerevisiae YRH400 had decreased fermentation lag times in bioabated hydrolyzates. However, xylose metabolism in S. cerevisiae YRH400 was strongly affected by pH and acetate concentration.     

Enhanced bioactivity of Zanthoxylum schinifolium fermented extract: Anti-inflammatory,anti-bacterial,and anti-melanogenic activity

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