Micromechanical Simulation On Strength And Ductility Of Two Kinds Of Al-Based Nanostructural Materials

The nanostructured Al-based composites possess the combination of high yield strength and good ductility. In this paper, a micromechanical model is presented to simulate the mechanical response of bimodal nanostructured Al and the particle-reinforced aluminum matrix composite (PAMC). The constitutive relations for different phases are addressed in the model, as well as the contribution of microcracks. Numerical results show that the model can successfully describe the enhanced strength and ductility of the bimodal nanostructured Al, and the predictions of the PAMC are in good agreement with the experimental data. It is worth noting that the strength and ductility are sensitive to the volume fraction of constituents and the distribution of microcracks in both bimodal nanostructured Al and PAMC. Therefore, the present theoretical results can be used to optimize the microstructure for improving the mechanical properties of nanostructured Al-based composites

Permeability and Disintegration Characteristics of Composite Improved Phyllite Soil by Red Clay and Cement

The bearing capacity of the phyllite soil subgrade can be greatly improved by red clay, but the water stability of the modified soil is still poor. Hence, the blended soil has been found to be unsuitable for the construction of high-speed railways. This paper proposes an innovative scheme, by adding appropriate amounts of cement and red clay concurrently, to improve phyllite soil, which achieves a higher bearing capacity of the subgrade immediately after compaction, while also solving the problem of insufficient water stability. Laboratory tests of the permeability and disintegration characteristics of phyllite soils improved by cement, red clay, and both were carried out. The test results show that the permeability coefficient and maximum disintegration rate of soil can be improved effectively by using both red clay and cement. It was found that the optimal combination scheme is to add 3% cement and 40% red clay to phyllite soil by mass. Under the optimal scheme, the permeability coefficient, maximum disintegration rate, and disintegration rate of the improved soil decreased by 90.02%, 90.30%, and 99.02%, respectively, compared with the phyllite soil. The microscopic study shows that the mechanism of red clay blending with phyllite is that the finer particles of red clay infill the pores among the phyllite particles, thus reducing its permeability coefficient. The mechanism of adding cement to the blending soil mainly results from the production of hard-setting new materials and the formation of a cementation network among the soil particles, which not only increases the shear strength of the soil, but also reduces the permeability coefficient and the maximum disintegration ratio of the soil. This work makes full use of the complementary characteristics of red clay and phyllite soil and the advantages of hard-setting new materials, which will provide a new idea for soil improvement of the phyllite soil in the future

The Arabidopsis Gene zinc finger protein 3(ZFP3) Is Involved in Salt Stress and Osmotic Stress Response.

Plants are continuously challenged by various abiotic and biotic stresses. To tide over these adversities, plants evolved intricate regulatory networks to adapt these unfavorable environments. So far, many researchers have clarified the molecular and genetic pathways involved in regulation of stress responses. However, the mechanism through which these regulatory networks operate is largely unknown. In this study, we cloned a C2H2-type zinc finger protein gene ZFP3 from Arabidopsis thaliana and investigated its function in salt and osmotic stress response. Our results showed that the expression level of ZFP3 was highly suppressed by NaCl, mannitol and sucrose. Constitutive expression of ZFP3 enhanced tolerance of plants to salt and osmotic stress while the zfp3 mutant plants displays reduced tolerance in Arabidopsis. Gain- and Loss-of-function studies of ZFP3 showed that ZFP3 significantly changes proline accumulation and chlorophyll content. Furthermore, over-expression of ZFP3 induced the expressions of stress-related gene KIN1, RD22, RD29B and AtP5CS1. These results suggest that ZFP3 is involved in salt and osmotic stress response

MADS-box Transcription Factor OsMADS25 Regulates Root Development through Affection of Nitrate Accumulation in Rice

MADS-box transcription factors are vital regulators participating in plant growth and development process and the functions of most of them are still unknown. ANR1 was reported to play a key role in controlling lateral root development through nitrate signal in Arabidopsis. OsMADS25 is one of five ANR1-like genes in Oryza Sativa and belongs to the ANR1 clade. Here we have investigated the role of OsMADS25 in the plant’s responses to external nitrate in Oryza Sativa. Our results showed that OsMADS25 protein was found in the nucleus as well as in the cytoplasm. Over-expression of OsMADS25 significantly promoted lateral and primary root growth as well as shoot growth in a nitrate-dependent manner in Arabidopsis. OsMADS25 overexpression in transgenic rice resulted in significantly increased primary root length, lateral root number, lateral root length and shoot fresh weight in the presence of nitrate. Down-regulation of OsMADS25 in transgenic rice exhibited significantly reduced shoot and root growth in the presence of nitrate. Furthermore, over-expression of OsMADS25 in transgenic rice promoted nitrate accumulation and significantly increased the expressions of nitrate transporter genes at high rates of nitrate supply while down-regulation of OsMADS25 produced the opposite effect. Taken together, our findings suggest that OsMADS25 is a positive regulator control lateral and primary root development in rice

Divergent Causes of Terrestrial Water Storage Decline Between Drylands and Humid Regions Globally

International audienceDeclines in terrestrial water storage (TWS) exacerbate regional water scarcity and global sea level rise. Increasing evidence has shown that recent TWS declines are substantial in ecologically fragile drylands, but the mechanism remains unclear. Here, by synergizing satellite observations and model simulations, we quantitatively attribute TWS trends during 2002-2016 in major climate zones to three mechanistic drivers: climate variability, climate change, and direct human activities. We reveal that climate variability had transitory and limited impacts (<20%), whereas warming-induced glacier loss and direct human activities dominate the TWS loss in humid regions (∼103%) and drylands (∼64%), respectively. In non-glacierized humid areas, climate variability generated regional water gains that offset synchronous TWS declines. Yet in drylands, TWS losses are enduring and more widespread with direct human activities, particularly unsustainable groundwater abstraction. Our findings highlight the substantive human footprints on the already vulnerable arid regions and an imperative need for improved dryland water conservation

Efficient CO₂ Adsorption on Nitrogen-Doped Porous Carbons Derived from d‑Glucose

The synthesis of carbonaceous CO₂ adsorbents doped with nitrogen were carried out via a hydrothermal reaction of biomass d-glucose, followed by urea treatment and K₂CO₃ activation. These carbons display high uptake of CO₂ at 1 bar and 25 and 0 °C, up to 3.92 and 6.23 mmol g^–1, respectively. Additionally, the as-synthesized materials exhibit superior reusability, high CO₂/N₂ selectivity, fast CO₂ adsorption kinetics, and excellent dynamic capture capacity at the experimental conditions used. The synthetic effect of the nitrogen content and narrow microporosity decide the capture capacity for CO₂ at 1 bar and 25 °C for these N-enriched carbonaceous adsorbents. This study provides a viable method to prepare high-performance CO₂ carbonaceous sorbents without using caustic KOH. In addition, this work gives further insights into the CO₂ adsorption mechanism for nitrogen-doped porous carbon sorbents and, hence, inspires ways to synthesize novel carbonaceous materials for removing CO₂ from combustion exhaust gases

Effect of S-deprivation and re-supply on expression of <i>OsNRT2.1</i>, <i>OsNAR2.1</i>, <i>OsIPS1</i> and <i>OsSULTR1;1</i> in rice roots.

<p>Rice seedlings were grown hydroponically in a growth cabinet. Sulfur treatments were as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0105597#pone-0105597-g003" target="_blank">Fig. 3. C</a>: continuous complete nutrient supply; −S: starved of S; +S: resupplied with SO₄²⁻ for 3 h. Total RNA was extracted from roots and qPCR reactions were performed in triplicate for each RNA sample. The mRNA of <i>OsActin</i> was used as the reference. A Student’s t-test was calculated at the probability of either 5% (*, p<0.05) or (**, P<0.01).</p

Effect of different N sources on the expression of five <i>ANR1</i>-related genes in rice roots.

<p>Rice seedlings were grown in liquid culture for 14 days with 2.88 mM KNO₃ as the sole nitrogen source and then N starved for 3 d. CK, continuous N; −N, starved for 3 d; +KNO₃, resupplied with 2.88 mM nitrate; +NH₄Cl resupplied with 2.88 mM NH₄⁺; and +Gln, resupplied with 2.88 mM glutamine; +NH₄NO₃, resupplied with 1.44 mM NH₄NO₃. The value of related genes were normalized to its CK control respectively. The mRNA of <i>OsActin</i> was used as the reference. Error bars represent _{SE. LSD} values were calculated at the probability of either 5% (*, p<0.05) or (**, P<0.01).</p

Effect of N-deprivation and re-supply on expression of <i>OsNRT2.1</i>, <i>OsNAR2.1</i>, <i>OsIPS1</i> and <i>OsSULTR1;1</i> in rice roots.

<p>Rice seedlings were grown hydroponically in a growth cabinet. Nitrogen treatments were as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0105597#pone-0105597-g001" target="_blank">Fig. 1</a>. CK: continuous KNO₃; −N4h: starved of N for 3 d and resupplied with KCl for 4 h; +N4h: resupplied with KNO₃ for 4 h; −N6h: starved of N for 3 d and resupplied with KCl for 6 h; +N6h: resupplied with KNO₃ for 6 h. Total RNA was extracted from roots and qPCR reactions were performed in triplicate for each RNA sample. The mRNA of <i>OsActin</i> was used as the reference. A Student’s t-test was calculated at the probability of either 5% (*, p<0.05) or (**, P<0.01).</p