Search

This work carefully revisits the topic of dynamic feedback $ H_{\infty } $ H ∞ control problem for discrete singular systems (DSSs) with time–varying delays. A new state decomposed Lyapunov-Krasovskii functional is presented by a discrete state decomposition method. For the unforced nominal DSSs, delay–dependent sufficient conditions with an $ H_{\infty } $ H ∞ performance index are derived. Based on these conditions, a closed–loop system being regular and causal is developed via a dynamic feedback controller. As a new discrete state decomposition–reorganization method is proposed, the required admissibility conditions are attained. Through the accurate calculation of each decomposition component of the dynamic feedback controller, the desired dynamic feedback controller settings are determined. The numerical findings demonstrate the superiority of our method over earlier approachers, and the results are less conservative. [ABSTRACT FROM AUTHOR]

Neonicotinoid pesticides are widely applied for controlling pests in a variety of agriculture crops. Due to the systemic distribution in plants, neonicotinoid pesticides have been found in nectar and pollen, which are the main source of food for the important pollinator honeybee. The risk of neonicotinoid residues in honeybee products and honeybee has caused great attention since their impacts on the environment, ecology, and food safety issues. These concerns require the accurate and sensitive determination of neonicotinoids and their metabolites in the honeybee products and honeybee. Since the trace residue level of neonicotinoid and the complexity of the samples, analysis of neonicotinoid targets in these important matrices is still a great challenge. The present review provides general overview of analytical methods for the determination of neonicotinoid pesticides and their metabolites in honeybee products and honeybee. [ABSTRACT FROM AUTHOR]

The synthesis conditions of HZSM-5 zeolite, including crystallization temperature, crystallization time and raw material ratio, were investigated by L32 (48) orthogonal test to specifically optimize its performance in dimethyl ether (DME) aromatization for the first time. Based on the total yield of aromatic products, the synthesis conditions of HZSM-5 zeolite with the best DME aromatization properties were obtained by comprehensive analysis and validation experiments. The relationship between the aromatization performance, crystalline structure, pore structure, and acidity of HZSM-5 zeolite were analyzed. The results showed that the HZSM-5 zeolite accompanied by hierarchical structure, an appropriate Brønsted and Lewis acid content and uniform crystal morphology, was successfully synthesized under optimized conditions. Over this unmodified and un-doped catalyst, the conversion of DME approached to 99.3% and the total yield of aromatics reached was 53.5%. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of delay-dependent stability analysis for systems with interval time-varying delay. By means of a new double free-matrix-based integral inequality and augmented Lyapunov–Krasovskii functionals containing as much information of time-varying delay as possible, a new stability criterion for systems is established. Firstly, by a double integral term two-step estimation approach and combined with single free-matrix-based integral inequalities, a stability criteria is presented. Then, compared with the double integral term two-step estimation approach, the proposed new double free-matrix-based integral inequality with more related time delays has potential to lead to a criterion with less conservatism. Finally, the validity of the presented method is demonstrated by two numerical examples. [ABSTRACT FROM AUTHOR]

The deformable layer tomography (DLT) is now a popular way to characterize the unknown geometry of the velocity interface by using the traveling time observed in data, which is difficult to solve accurately, because of the strong ill-posedness. In this paper, new regularization approaches based on the spectral method are introduced, which can invert the velocity value and the geometry of the interface simultaneously. The unknown interfaces are parameterized by Legendre spectral expansion, and various regularization methods combined with traditional regularization parameters selections are utilized to solve the ill-conditioned algebraic equation system. Moreover, a regularized algorithm with prior choice of regularization parameters is proposed to solve the DLT. [ABSTRACT FROM PUBLISHER]

Bacterial cellulose (BC) was chosen as carrier of nanometer titanium dioxide due to its superfine network structure. BC/titanium dioxide composite membrane was prepared by a sol–gel method using tetraisopropyl titanate as starting material. Photocatalytic properties of composite membrane were studied using methyl orange as degradation agent. Titania nanoparticles were successfully loaded on bacterial cellulose membrane. The degradation rate of methyl orange solution was up to 100% under ultraviolet (UV) irradiation. [ABSTRACT FROM AUTHOR]

Bacterial cellulose (BC) was chosen as a support for nanometer titanium dioxide (TiO2) particles due to its superfine network structure. The composite membrane of TiO2/BC doped with rare earth elements was prepared by a sol-gel method using tetraisopropyl titanate as starting material. Photocatalysis properties of this composite membrane were estimated by using methyl orange as a degradation agent. X-ray fluorescence (XRF) spectra showed that rare earth ions were incorporated into TiO2/BC membrane. X-ray diffraction (XRD) spectra showed that the resulting titanium dioxide was anatase type, which didn't change after doping. Compared with a pure TiO2/BC membrane, photocatalysis efficiency was significantly enhanced for the doped one. The degradation rate of methyl orange solution for a composite membrane doped with Ce4+ was up to 100%, while with La3+ it was was up to 79.7%. The optimal dosage of Ce4+ was 2 mmol/L, while the most suitable concentration of La3+ was 5 mmol/L within the experimental range. [ABSTRACT FROM AUTHOR]

In this article, we describe the use of diphenyl carbonate (DPC) as a carbonyl source instead of isocyanate to synthesize asymmetric substituted urea derivatives. In a study aiming to discover new lead compounds with agricultural activities, thiazole[5,4-b]pyridine ureas were prepared by this method and characterized by mass spectrometry, elemental analysis, and 1H NMR spectroscopy. The biological activities show that the title compounds have moderate activities on herbicide, fungicide, and plant growth regulation. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. GRAPHICAL ABSTRACT[image omitted] [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effects of dietary supplementation with Glycyrrhiza polysaccharide (GCP) on growth performance, serum biochemistry, immunity, and egg laying in female quail. 300 1-day-old female quail were sorted into four dietary treatments with five replicate cages of 15 birds each. The basic diet in the four treatment groups was supplemented with 0, 500, 1000 and 1500 mg/kg GCP, and the experiment continued for 80 days. Results showed that dietary supplementation with GCP significantly (p < 0.05) increased average daily gain in a dose-dependent fashion, and decreased (p < 0.05) the feed-to-gain ratio and mortality. The relative weights of the thymus and bursa of Fabricius increased (p < 0.05) linearly with increasing dose of GCP from 0 to 1500 mg/kg on day 20. GCP birds showed higher serum levels of protein, glucose, immunoglobulin A and immunoglobulin M, but lower serum triglycerides (p < 0.05) on day 50. GCP increased (p < 0.05) average laying rate and average egg weight linearly from days 60 to 80, whereas feed to egg ratio was decreased (p < 0.05). Taken together, these results revealed that GCP could improve growth performance, serum biochemistry, immunity, and egg laying in female quail. Therefore, GCP may be a potential replacement for antibiotic growth promoters in poultry. [ABSTRACT FROM AUTHOR]

Silver nanoparticles have been prepared by reducing a silver nitrate precursor and loaded on the surface of bacterial cellulose (BC)in situto form Ag/BC composite membrane. The membrane microstructure was characterized by using scanning electron microscope (SEM). The SEM images showed that the number of the silver nanoparticles with diameters in the range of 50–80 nm increases with higher silver nitrate concentration. X-ray diffraction spectra results indicated that the silver nanoparticles are with face-centered cubic structure. X-ray fluorescence spectrum showed that Ag element was incorporated into the bacterial cellulose. UV-Vis results showed characteristic silver absorption peak at 424 nm. Both antimicrobial activity and biocompatibility of the Ag/BC nanocomposites have been evaluated. The silver nanoparticles exhibited good antimicrobial activities againstE. coliandS. aureus.The antibacterial ratio againstE. coliandS. aureusreached 99.4% and 98.4%, respectively. The Ag/BC composite membrane also showed better biocompatibility. The results suggest that our Ag/BC membrane may find applications for antimicrobial purposes, for example, antibacterial wound dressings. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the variation of milk mineral and chemical components in colostrum and milk corresponding to milking time and lactation day. Samples were collected at 1, 7, 14 and 21 days postpartum, and the effects of milking time (diurnal milk/nocturnal milk) on mineral and chemical components were studied. Results showed that the mineral levels, as well as fat, protein, lactose and total solid, were significantly affected (P < 0.01) by lactation day. The content of Na, K, Ca, and the ratio of Na/K were affected (P < 0.05) by milking time on day 7 and 14 of lactation, whereas this effect was inconclusive for the other days. Chemical components were not affected by milking time, although the proportion of total solids in the milk tended to decrease (0.05 < P < 0.10) in nocturnal milk on day 14 of lactation. Significant correlations were observed among milk minerals or chemical components (P < 0.05), although there were slight correlations between milk mineral and chemical component. These findings showed that milk minerals and chemical components in sows could be affected by milking time and lactation day to some extent, which may provide a reference for milking parameters. [ABSTRACT FROM AUTHOR]

The Lunpola oil shale is the largest oil shale resource in Tibet. Twenty-four samples were collected from this deposition to determine the platinum group element (PGE) characteristics. The total PGE contents in terrestrial oil shale are low (average 2.386 ng/g). The PGEs are enriched in the oil shale samples near the boundary between the oil shale and its underlying strata. The PGE enrichment may be the result of a change of oxic–anoxic conditions. The individual PGEs of oil shale samples from the Lunpola oil shale exhibit similar modes of occurrence, and their distributions are controlled mainly by Fe-bearing minerals (pyrite). The source of PGEs in the Lunpola oil shale is probably related to water chemistry and terrigenous supply. [ABSTRACT FROM PUBLISHER]

The Bilong Co oil shale, located in the South Qiangtang depression, northern Tibet Plateau, may record the Early Jurassic anoxic event in the eastern Tethys. New geochemical data from the Bilong Co oil shale section are presented in order to determine the mechanism of organic accumulation and to evaluate Early Jurassic anoxia in the eastern Tethys. In organic-rich oil shales, many redox proxies including the relationship of Mo to total organic carbon (TOC), Re/Mo ratios, and pyrite framboid size distribution suggest deposition under euxinic conditions. However, the correlation between TOC and P and Mo contents indicates that organic matter accumulation was controlled mainly by primary productivity. The Sr/Al ratios and clastic influx proxies such as Si, Ti, Th, Zr, and Al concentrations suggest a continuous supply of fresh water from a nearby continent during oil shale deposition. This supply could have initiated stratification of the water so that the upper zone became favourable for marine life. Increased primary productivity could have led to formation of anoxic/sulphidic bottom waters, which enhanced the preservation of organic matter. Deposition of organic-rich oil shales terminated when primary productivity decreased, leading to more oxic bottom water conditions. [ABSTRACT FROM PUBLISHER]