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Polyaspartic acid/chitosan complex (PASP/CS) was synthesized by the reaction of Polyaspartic acid, chitosan, and glutaraldehyde. The graft copolymer (PASP/CS) was characterized by FT-IR. The inhibition corrosion efficiency of the complex was estimated as 83.5%, PASP and only 58.8% when inhibitor concentration was 8 mg/L. PASP/CS is an anodic corrosion inhibitor in Sodium Chloride Solution. The competitive adsorption of chloride ions and PASP/CS in water can form a layer of dense molecular film on the carbon steel surface composite with a non-location effect. PASP/CS combination can effectively inhibit the corrosion in the carbon steel system. The steel surface morphology was analyzed using scanning electron microscopy (SEM) and an adsorption mechanism model is proposed. The high inhibition efficiency of PASP/CS is related to the adsorption of polymer molecules on the steel surface and the formation of a protective film that can successfully inhibit the erosion of corrosive media and prevent the corrosion of carbon steel in the process.
This study takes the Southern antimony smelting slag depot in Xikuangshan (XKS) Sb mine in the city of Lengshuijiang, Hunan, China, as the research object and explores the release law of Sb, As, and Hg in smelting slag under different pH-value simulated acid rain by a semi-dynamic leaching experiment of simulating the local rain. The results show that the leachate pH value is positively correlated with the pH value of simulated acid rain, while the leachate conductivity is negatively correlated with it. The leaching rates of As and Hg are negatively correlated with the pH value of the simulated acid rain, while the leaching rate of Sb is positively correlated with it; in the leaching process, the leachate pH value goes downward slowly after shooting up, but the leachate conductivity is continuously reduced; the releasing process of Sb, As, and Hg consists of two stages, and their leaching rate forms such an order as Sb > Hg > As. The diffraction peak intensity of the main mineral composition of quartz and calcite decreases significantly after leaching; the smelting slag’s surface becomes less rough than before leaching, with fewer pores and edges, and the contents of S, Si, Al, Fe, Ca, and Sb on the slag surface decrease while the content of O, As, and Hg increases.
Antimony ore tailings slag was used analyze heavy metals, chemical speciation, and leaching characteristics. The results show that the residual silicate phases account for 65.44% of Sb, 77.22% of As, 87.94% of Hg, 58.53% of Pb, 71.27% of Cd, and 96.34% of Zn. Although the exchangeable and carbonate phases account for 7.71% of Sb, 0.71% of As, 3.77% of Hg, 4.82% of Pb, 1.83% of Cd, and 1.73% of Zn, the water-or-acid-soluble phases contribute more to the chemical speciation of heavy metals. Concentrations of Sb, As, and Hg in the leachates increased with increasing solid-liquid ratio, decreasing particle size and increasing temperature. In simulated rainfall conditions, the total quantity increased in the order Sb > As > Hg and were 42.508 mg, 52.940 μg, and 0.876 μg, respectively, at 500 g antimony ore tailings. Under different rainfall intensity simulations, the maximum quantity in the leachates of Sb, As, and Hg were 93.894 mg, 255.451 μg, and 1.690 μg, respectively, and increased in the order of moderate > heavy > rainstorm. Finally, the cumulative leaching of Sb at pH 6.0 is 42.025 mg/L (higher than at 4.0 and 5.0), and the As and Hg at pH 4.0 are 107.097 μg/L and 0.989 μg/L, respectively.
Three new Myrmica species (M. sinensis, M. angulata and M. draco) are described from the Southern China. Their taxonomic position is discussed and some ecological data for M. serica is provided. All the species belong to the ritae-group of Myrmica.
In order to investigate the concentrations of selenium (Se) in plants of the Dashan Region, a typical Se-rich area of China, and to illuminate the daily dietary Se intake of residents in this region, 83 crop samples and 144 Chinese herb samples were collected. Total Se was analyzed in the edible portion of crops and the medical portion of Chinese herbs. The average concentrations of Se ranged from 100 to 3,100 μg kg⁻¹ (dry weight/DW) in different crops and from 20 to 1,500 μg kg⁻¹ in the Chinese herbs (DW). The crop that contained the highest concentrations of Se was radish, while maize contained the lowest levels. For the Chinese herbs, the highest concentrations of Se were found in Rumex japonicas, while Cape jasmine contained the lowest levels of Se. The average enrichment coefficients (ECs) were 6.1-300% in crops, and 1.6⁻¹17% in Chinese herbs. Among the crops, radish had the highest EC (300%), while pumpkin had the lowest (6.1%). Among the Chinese herbs, Sapium sebiferum had the highest EC (117%), while Dicranopteris dichotoma had the lowest (1.6%). Based on the composition of residents’ daily diets, the estimated daily Se intake from crops was 282±20 μg day⁻¹, and was about 5 times higher than the RDA value suggested by WHO (55 μg day⁻¹). Although no selenosis incidents have occurred in the Dashan Region to date, the potential health risk caused by chronic exposure to high levels of Se cannot be ignored.
We studied the wing morphology, echolocation calls, diet and emergence time of the black-bearded tomb bat (Taphozous melanopogon) from May to October 2006 in Guangxi Province, southwest China. Taphozous melanopogon has wings with high aspect ratio, high loading and pointed wing-tip shape-characteristics associated with fast flight in open space. This species usually produces low-intensity, low frequency, and frequency-modulated (FM) calls usually containing up to four harmonics, with most energy in the second (or sometimes third) harmonic. The diet of this species consists mostly of Lepidoptera and Hemiptera. Timing of evening emergence is correlated with the time of sunset. This is the first study to describe the flight and echolocation behavior of this species in China, and opens the way for future studies of its biology.
This study aims to investigate the effects of oxytetracycline on growth and photosynthetic capacity of rape (Brassica campestris L.). Four levels of oxytetracycline (0, 10, 100, and 200 mg kg⁻¹) were added to the potted soil. Chlorophyll fluorescence parameters induced by five levels (90, 190, 420, 820, and 1,500 μmol photons m⁻² s⁻¹) of PAR (PAR, photosynthetically active radiation) were measured. Plant growth indices and leaf traits were also determined. Electron transport rate increased along with the increase of PAR, but an opposite trend was found for the effective quantum yield of PSII. The quantum yield of light-induced non-photochemical fluorescence quenching in higher oxytetracycline treatments (100 and 200 mg kg⁻¹) gradually increased when PAR increased from 90 to 820 μmol photons m⁻² s⁻¹, but then declined under higher PAR gradients. The fractions of quantum yield of non-light-induced non-photochemical fluorescence quenching in PSII were significantly higher in all the oxytetracycline treatments than in the control. Oxytetracycline exposure was also found to alter the energy distribution in the photosynthetic electron transport chain. This study showed that oxytetracycline exposure evidently diminished the photosynthetic capacity of rape, which was further supported by the observations that growth indices and leaf traits were significantly inhibited by oxytetracycline.
Rainfall and seismic activity have significant influence on the stability of dangerous rockmass. In this paper, the dangerous rockmasses are classified into three instability types according to the failure modes: sliding, falling, and toppling. The discrete element method (COMSOL) was carried out to investigate the stability of three different rockmass types. In the numerical simulation, three load combinations were applied to the numerical model: 1) rockmass weight, 2) rockmass weight + fissure water pressure, and 3) rockmass weight + fissure water pressure + earthquake force. The results show that rainfall and seismic activity play important roles in rockmass stability and the displacement and principal stress of the rockmass are influenced obviously. Wangxia dangerous rockmass in the Great Three Gorges area was selected as a case study, and its stability was analyzed by geological investigation, numerical simulation, and static calculation methods. The results show that there is a high risk that Wangxia dangerous rockmass would lose stability when rainfall season comes and seismic activity happens. A blast was conducted to remove this dangerous rockmass and an SNS net design was proposed to intercept distributed blocks based on rockfall trajectory simulation. The parameters needed in the rockfall simulation program were obtained by laboratory and field tests. Final application proved that the designed treatment is efficient and no damage was caused by the distributed blocks. The whole research may provide a useful reference to similar engineering projects in the future.
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