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By first-principles calculation, elastic properties of seven single phase high-entropy alloys (HEAs) with excellent properties are presented in our work. A new method Maximum Entropy (MaxEnt) was adopted. The method is an algorithm that can be used to study the lattice distortion effect of HEAs. CP2K first-principles simulation package was employed for calculation. The comparison of calculated elastic properties of TaNbHfZrTi with experimental data is made and the agreement is found to be quite good. Elastic properties of AlMoNbTiV are close to the calculated data from Coherent Potential Approximation (CPA), and the reasons were discussed. The influence of lattice distortions on elastic properties were also studied. Furthermore, elastic properties of a series of refractory HEAs were predicted. These results demonstrate that MaxEnt model can properly describe HEAs.

Periodic chemically homogenized high-entropy alloy structures are constructed according to maximum entropy principle. The method can efficiently generate equimolar and non-equimolar high-entropy alloy atomic structures. Nine high-entropy alloys are simulated based on the constructed models using density functional theory techniques. The calculated lattice parameters are consistent with the available experimental data. The calculated enthalpies of mixing are more negative than the values estimated by using Miedema model, due to severe lattice distortion. The lattice distortion parameters were calculated. The results showed that fcc structure tend to stable with smaller and bcc structure with larger. The bulk modulus of Al1.5CoCrNiFe high-entropy alloys was fitted and the value is consistent with the available experimental data.

Adsorption isotherms play an important role in preparation chromatography, which is the basis of procedure design and optimization. For a binary competitive system, the adsorption isotherm constant G is generally derived from linear chromatography. However, the adsorption isotherm coefficient b is difficult to measure, especially for separations accompanied by a reaction. In previous studies, the effect of enzymes has often been simplified or ignored due to its complexity. In the present paper, b was calculated using nonlinear reaction chromatography theory and the reaction rate constant k r . The obtained results were compared using several experimental methods, such as the elution method and the dynamic Michaelis–Menten method, the results of which were generally in agreement. The feasibility of the method was discussed. The method presented herein might provide a simple way to determine the adsorption isotherm of reaction chromatography when enzymes are involved.

Cadmium (Cd) has been identified as a significant pollutant due to its high solubility in water and soil and high toxicity to plants and animals. Rice, as one of the most important food crops, is grown in soils with variable levels of Cd and therefore, is important to discriminate the Cd tolerance of different rice cultivars to determine their suitability for cultivation in Cd-contaminated soils. This study investigates the primary mechanisms employed by four rice cultivars in attaining Cd tolerance. HA63 cultivar reduces Cd uptake by increasing Fe absorption through activation of phytosiderophores. T3028 cultivar accumulates the highest level of Cd in leaves while also activating its reactive oxygen species (ROS) scavenging system, including antioxidant enzymes and phytochelatins. In some rice cultivars (such as HA63), a cyanide-resistant respiration mechanism, important in Cd detoxification, was also promoted under the Cd stress. In conclusion, different rice cultivars may adopt different biochemical strategies and respond with different efficiency to Cd stress.

Using a first-principles method based on density functional theory, we have investigated energetics and site preference of helium (He) in a ferromagnetic bcc-iron (Fe) ∑ 5 ( 3 1 0 ) / [ 0 0 1 ] grain boundary (GB). We calculate the binding energies of He atom in the GB, which show that the substitutional He is energetically favored in comparison with the interstitial He with a small energy difference of 0.06 eV. The segregation energy is calculated to be ∼1.4 eV for the energetically favorable GB substitutional and interstitial sites, which is large enough for the He atoms to segregate to these sites, independent of the temperature and the bulk He concentration. This leads to the conclusion that all the He atoms will segregate into the GB at a typical temperature range of 573–1173 K.

A tree gum which is mainly composed of natural heteropolysaccharides, namely PG gum, was presented. The rheological characteristics of PG gum based drilling fluids at different concentrations and aging temperatures were studied by means of a rotating rheometer. The effects produced by the addition of inorganic salts (NaCl and CaCl2) on the rheological properties of PG gum based drilling fluids were also studied. The results show that PG gum based drilling fluids investigated behaves as non-Newtonian shear-thinning fluids. With the increase of PG gum concentrations from 0.5% to 2.5%, the consistency coefficient increases while the viscosity behavior index decreases. The aging experimental data indicate that temperature has a slight effect on the rheological properties of PG gum based clay suspensions when the aging temperature is below 120 °C. Whereas, when temperature is above 120 °C, the rheological parameters of the suspensions, containing apparent viscosity, plastic viscosity and yield point, decrease significantly. The PG gum shows a better resistance to an increase in salinity or divalent cations concentration.

This work reports on the toxicity of CuO nanoparticles (NPs) to maize (Zea mays L.) and their transport and redistribution in the plant. CuO NPs (100 mg L(-1)) had no effect on germination, but inhibited the growth of maize seedlings; in comparison the dissolved Cu(2+) ions and CuO bulk particles had no obvious effect on maize growth. CuO NPs were present in xylem sap as examined by transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS), showing that CuO NPs were transported from roots to shoots via xylem. Split-root experiments and high-resolution TEM observation further showed that CuO NPs could translocate from shoots back to roots via phloem. During this translocation, CuO NPs could be reduced from Cu (II) to Cu (I). To our knowledge, this is the first report of root-shoot-root redistribution of CuO NPs within maize. The current study provides direct evidence for the bioaccumulation and biotransformation of CuO NPs (20-40 nm) in maize, which has significant implications on the potential risk of NPs and food safety.

The effects of nano-rutile TiO2 and multiwalled carbon nanotubes on the growth and antioxidant enzymes of maize (Zea mays L. ) seedlings were investigated under hydroponic conditions. Nano-rutile TiO2 (or =50 mg/L) significantly decreased root and shoot growth (p0.05) after 9 days, while MWCNTs did not influence the biomass obviously. Under two stress conditions, the antioxidant system was activated respectively. Compared to the control, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were up-regulated (p0.05). Lipid peroxidation in terms of malondialdehyde (MDA) content was enhanced by TiO2 exposure, whereas, MWCNTs did not cause oxidative damages in maize seedlings. The results indicated that the phytotoxicity of nano-rutile TiO2 was much higher than that of MWCNTs, and oxidative stress induced by nanoparticles (NPs) exposure might play a role in the phytotoxicity of NPs. The remarkable effect of nano-rutile TiO2 is probably attributed to particle composition and shape.

The effects of Cd stress (200 μmol/L, 8 days) on respiration and photosynthesis of three wheat cultivars were investigated: Chuanyu 12 (CY12), Chuanmai 42 (CM42), and Chuanmai 47 (CM47). Fifteen-day-old seedlings were exposed to 200 μmol/L CdCl2 for 4 days and 8 days, respectively. The results indicated that Cd was accumulated largely in roots, but little in leaves of all three cultivars. CY12 accumulated the highest level of Cd in roots and showed the weakest resistance. On the contrary, the other two cultivars, CM42 and CM47, adapted better to Cd stress, and their thiobarbituric acid-reactive substances (TBARS) contents were lower than in CY12, but the chlorophyll contents and water contents were higher than in CY12. Additionally, Cd stress prompted the alternative oxidase (AOX) activity and upregulated the cyanide-resistant respiration in CM42 and CM47 after 8 days; no such induction was observed for CY12. The CO2 assimilation rate, leaf stomatal conductance and chlorophyll fl uorescence were inhibited by Cd stress in all cultivars, but more severe in the CY12 cultivar. Western blots indicated that the content of the photosystem II proteins LHCII and D1 decreased in CY12, but did not change in CM42 and CM47. While the content of the mitochondrial AOX protein increased markedly in CM42 and CM47, it did not in CY12. These results suggested that AOX and LHCII could be regarded as indicators of plant’s resistance to heavy metals.

In order to tackle the problem of Cd pollution in paddy soils and investigate soil available Cd as affected by different fertilizers, incubation experiments were carried out to study the effects of different N, P and K fertilizers and pH by adding acid or base on soil available Cd under waterlogged conditions. Results revealed that soil pH increased sharply after the soil was flooded, especially at the beginning of incubation, and gradually decreased with incubation time and finally tended to approach the neutral values. The patterns of soil pH change were just opposite to those of soil available Cd, a negative correlation observed between the two. Soil flooding made the soil available Cd drop by 58.2%-84.1%. There were significant differences between different fertilizer types/varieties on soil available Cd, being most complex with N fertilizers and followed by K and P fertilizers. Among the fertilizers studied, ammonium chloride showed the unique ability in reducing soil pH and enhancing soil available Cd, and urea, single super phosphate and potassium chloride also promoted to a less extent amounts of Cd extracted from the soil. Ammonium sulfate, potassium sulfate and mono-ammonium phosphate significantly decreased soil available Cd compared to the CK treatment. Whether or not the soil was flooded, soil available Cd was highly negatively correlated with soil pH after adding acid or base (R = - 0.994 without incubation and R = - 0.919 after incubation for 60 d). The results further suggest that in the Cd polluted paddy soil, use of ammonium chloride should be avoided, S bearing fertilizers in combination with alkaline materials can be adopted, and the rice field should be flooded all the time during growing season, all the these practices can effectively lower soil available Cd.

A problem of higher background value and lower measured Cd value exists when Cd is digested by conventional dry digestion method, measured by graphite furnace atomic absorption, and calculated with peak height numeration. This problem results in difficulty for evaluating samples with Cd contents in the neighborhood of critical values. In order to solve the problem, the present paper focused on background measurement with graphite furnace atomic absorption, modified the pre-preparation procedures of the traditional method, and screened the optimal concentration of the modifier. Results showed that addition of Mg (NO3)2 as a modifier into the samples before incineration was preferred. It could not only yield a clear solution but also reduce its background by ten times, considerably eliminating background interference. In addition, using 3% HNO3 in stead of 1 mol x L(-1) HCl as dilution for the incinerated sample could eliminate the background. The improved methods could acquire a zero concentration of measurement for the blank, re-correct the values measured by graphite furnace atomic absorption and obtain more reliable results.

In this paper, we present Monte Carlo simulations of A-B-diblock-copolymer ternary mixtures simultaneously undergoing phase separation and reversible chemical reaction A + B ⇌ C . The results demonstrate that the competition of chemical reaction and thermal diffusion dynamics co-determine the self-assembling morphology and growth kinetics of the reactive ternary mixtures. The role of the chemical reaction on the growth kinetics count mainly on the copolymer–polymer interaction strength Jp. If Jp < 1.0, the introduction of chemical reaction speeds up the domain growth; while for Jp > 1.0, the chemical reaction slows down the domain growth. The domain growth exponent decreases linearly with increasing of the copolymer–polymer interaction strength. At a later stage, 〈1, 0〉 and 〈0, 1〉 oriented strip pattern formations are observed when Jp is strong.