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With the development of agriculture and the widespread application of agrichemicals in Tibet, herbicide residues have become a threat to the ecological safety of Tibetan water bodies. Algae, as the producers in the food chain in water bodies, play an important role in aquatic ecosystems. Therefore, the impact of herbicides on Tibetan algae is of great significance for evaluating ecological health and the protection of Tibetan water ecosystems. In this study, we investigated the inhibitory effect of glyphosate, a herbicide, on the photosynthetic system of

This paper discusses the current development strategy, technology and industrialization of China's hydrogen energy industry in the transportation field, summarizes the characteristics and development experience, and makes a comparative study with the situation of some developed countries. The results show that the current development of hydrogen energy has formed a broad consensus in China and is becoming the overall development of China's national level consciousness. However, China's hydrogen energy industry is still facing problems such as high cost of comprehensive utilization, imperfect standards and regulations for hydrogen energy utilization, obvious tendency of industrial blind development and structural overcapacity risk. Therefore, some policy suggestions were proposed for the future development, such as strengthening top-level design, strengthening pilot demonstration, promoting the development of the whole hydrogen industry chain, and reducing the cost of hydrogen and fuel cell vehicles in the field of transportation.

In this work, polyurethane/fluorinated acrylic co-polymer/silicon dioxide (PU/FAP/SiO2) hybrid superhydrophobic coatings were fabricated on glass substrates via a simple one-step coating process. The effects of each coating component on the coating properties were systematically investigated. The optimized coating exhibits a water contact angle (WCA) of 159° and a rolling angle of 3°. Meanwhile, the coating has an optical light transmittance of 88%, indicating the good transparency of the coating. Besides, the coating demonstrates an adequate level of abrasion resistance. After a total abrasion distance of 300 cm against a piece of 800 mesh sand paper, the sample still kept a water contact angle of about 110°, showing its high abrasion resistance. Therefore, the optimized coating has a great potential for practical application.

The gas pipelines usually undergo complicated and changeable regional environment. As the level of the potential difference or pipeline’s route changes in the space and therefore elastic bending cannot meet the needs when pipe changes its direction, we generally use pipe bend to connect two pipelines with different spatial extend direction during the pipe laying period, and it can reduce the temperature stress. Unreasonable design of elbow will lead to pipeline damage. We established mountain area pipeline model, and conducted analysis on pipeline stress under different elbow angles. Research shows that different angles of the bends suffer different operation stress, and we have come to the conclusion that the angle of pipe bends should not be within the range of 15 degrees to 35 degrees.

It is necessary to estimate heavy metal concentrations in plants for understanding the heavy metal contaminations and for keeping the sustainable developments of ecosystems and human health. This study, with the Le’an River and its two branches in Jiangxi Province of China as a case study, aimed to explore the feasibility of estimating concentrations of heavy metal lead (Pb), copper (Cu) and zinc (Zn) in Phragmites australis using laboratory-based hyperspectral data. 21 P. australis leaf samples were collected, and their hyperspectral data, chlorophyll concentration and Pb, Cu and Zn concentrations were measured within the laboratory. The potential relations among hyperspectral data, chlorophyll concentration and Pb, Cu and Zn concentrations were explored and employed to estimate Pb, Cu and Zn concentrations from hyperspectral data with chlorophyll concentration as a bridge. The results showed that the linear combination of normalized band depths at wavelengths 537 (green), 667 (red) and 747 (near infrared) nm could explain 82% of the variation of chlorophyll concentration; the Pb, Cu and Zn concentrations were significantly and negatively related to the chlorophyll concentration, and the chlorophyll concentration could explain around 30% of the variations of Pb, Cu and Zn concentrations, respectively; and the absolute estimation errors for more than 80% estimations of Pb, Cu and Zn concentrations were less than 30%. We conclude that the laboratory-based hyperspectral data hold potentials in estimating concentrations of heavy metal Pb, Cu and Zn in P. australis . More sampling points and spectral characteristics-based methods should be collected and employed for improving the stabilities and accuracies of estimation models.

The Zhangjiakou-Xuanhua area is a mineral resource-concentrated area for gold-silver polymetallic ore deposits. The temporal and spatial distribution and origin of mineral resources have been argued for a long time. Based on the comprehensive studies of geochronology and sulfur, lead, oxygen, carbon and noble gas isotopes, it is considered that the temporal and spatial distribution of mineral resources in this area is obviously controlled by the Zhangjiakou-Xuanhua mantle branch structure, as is reflected by the occurrence of gold deposits in the inner parts and of Ag-Pb-Zn polymetallic ore deposits in the outer parts. The mineralization took place mainly during the Yanshanian period. Ore-forming materials came largely from the deep interior of the Earth, and hydrothermal fluids were derived predominantly from Yanshanian magmatism.

In this work, a new kinetic method was proposed for quantification phenoxyl radicals generated in enzyme reaction. Instead of direct detecting the spectral signals of phenoxyl radicals, a molecular probe, the reduced form of nicotinamide adenine dinucleotide (NADH), was employed to indicate the formation of phenoxyl free radicals. It was found that the reactions of NADH and phenoxyl radicals are very fast, but can be followed by using stopped-flow fast scanning spectrophotometric technique. The initial rate of accelerated-oxidation of NADH represents the reactivity of phenoxyl free radical, which is proportional in a certain range to the initial concentration of the parent chlorophenols of the radicals. With this method, the phenoxyl radicals generated in oxidation reaction of chlorophenols (2-CP; 4-CP; 2,4-DCP; 2,4,6-TCP and 2,3,4,6-Tetra-CP) with hydrogen peroxide, catalyzed by horseradish peroxidase, were investigated. The method is highly sensitive. Phenoxyl radicals generated from as low as 1 × 10−8 M 2,4-DCP, for example, can be readily detected with the proposed method. The results show that the reactivity of various phenoxyl radicals are in the following order: 2,4-DCP > 4-CP > 2-CP > 2,4,6-TCP > 2,3,4,6-Tetra-CP. A mechanism is proposed to explain the possible pathway of the probe reaction. The feasibility of this method was assessed by the determination of enzymatic generation of phenoxyl radicals in lake water samples.

A simple and highly sensitive method to quantify the rates of production of phenoxyl radicals in enzyme reaction is described. This method employs the peroxidase‐catalyzed reaction between chlorophenols and hydroperoxide to generate phenoxyl free radicals, which can enhance dimerization of L‐tyrosine. The product, dityrosine, was monitored fluorometrically at the excitation/emission wavelength of 320/410 nm and the initial rate of accelerated‐accumulation of dityrosine represents the formation rate of phenoxyl free radicals. With this method, the phenoxyl radicals generated in oxidation of chlorophenols with hydrogen peroxide, catalyzed by horseradish peroxidase, were investigated. Phenoxyl radicals generated from as low as 5.0×10−9 M 2,4‐dichlorophenol, for example, can be readily detected with a relative standard deviation of 2.6% for 9 replicated determination. The detection limits of phenoxyl radicals produced by various chlorophenols are 4.2×10−9, 1.1×10−9, 1.0×10−10, 2.8×10−8, and 1.1×10−7 ...

A simultaneous kinetic method based on the measurement of two rates at two points during the course of the successive reactions is proposed. The successive kinetics of the reaction of tris(1,10-phenanthroline)iron(III) with epinephrine (EP) and norepinephrine (NE) (10 −5 to 10 −4 M) is investigated and exploited for the determination of binary mixtures of the two catecholamines using the two-rate method. The method is compared with classical and extension proportional equation methods and a smaller error is obtained for the two-rate method. The reason why the two-rate method based on successive reactions works well is explained by studies on a series of simulated kinetic curves.

An error-compensated algorithm based on detecting the reagent in successive reactions is proposed. The algorithm was first studied by using simulated data and it was found that it performed well in compensating for the system error and eliminating random noise. Then the algorithm was examined by applying it to the determination of epinephrine and norepinephrine under different experimental conditions. The results revealed that the algorithm compensated errors produced not only by the changes of rate constants, but also by the variation of equilibrium signals.

An error-compensation algorithm based on a kinetic model of detecting intermediates in consecutive first-order reactions using the non-linear least-squares method was developed. A simulation study revealed that the algorithm performed well in compensating for the system error and eliminating random noise. It could offset the deficiency of low precision in kinetic analysis. The algorithm was applied to the determination of epinephrine, and the results were found to be reliable when the rate constants changed according to the variation of the experimental variables.

Study on the intermediary species of theophylline oxidation process is very important for understanding its pharmacological action. Theophylline is a drug commonly used in treatment of asthma. In our study, we found that a red intermediate which appeared and then disappeared immediately after we mixed Ce(IV) with theophylline. We have investigated this intermediate via rapid-scanning stopped-flow W/Visible spectroscopy combined with single wavelength stopped-flow technique. Successive reaction kinetic simulation model has been used to study properties of the intermediate. A possible reaction mechanism is proposed.

A selective kinetic method based on detecting the intermediate product in successive reactions was developed. The method relies on the peak-shaped kinetic curve resulting from the reaction and detection mode. The underlying principle of this method is choosing two proper measurement times where the interference species produces equal signal intensities while the analyte to be determined produces different signal intensities. So with the mixture, the difference in signals at these same two times yields a value related to the concentration of the analyte. This allows selective determination of one analyte in binary mixtures or simultaneous determination of both. The proposed method was applied to the selective determination of epinephrine in four catecholamine mixtures based on their successive reactions with dissolved oxygen in alkaline solution.

In this paper, a simple and sensitive fluorimetric method for the determination of tiopronin ( N -(2-mercaptopropionyl)-glycine) is proposed. The method is based on the strong inhibitory effect of tiopronin on the multienzyme redox system of hemoglobin, nicotinamide adenine dinucleotide (NADH) and H 2 O 2 , in which the intrinsic fluorescence of NADH was employed as the detection signal. The calibration graph is linear in the range 6.13 × 10 −7 to 6.13 × 10 −6 M with a detection limit of 1.65 × 10 −7 M and the relative standard deviation of 2.02%. Kinetics in the pseudo-first-order conditions was investigated by stopped-flow spectrofluorometry and the inhibition mechanism of tiopronin was verified of the competitive type.