Effect of partition coefficient on microsegregation during solidification of aluminium alloys

In the modeling of microsegregation, the partition coefficient is usually calculated using data from the equilibrium phase diagrams. The aim of this study was to experimentally and theoretically analyze the partition coefficient in binary aluminum-copper alloys. The samples were analyzed by differential thermal analysis (DTA), which were melted and quenched from different temperatures during solidification. The mass fraction and composition of phases were measured by image processing and scanning electron microscopy (SEM) equipped with an energy-dispersive X-ray spectroscopy (EDS) unit. These data were used to calculate as the experimental partition coefficients with four different methods. The experimental and equilibrium partition coefficients were used to model the concentration profile in the primary phase. The modeling results show that the profiles calculated by the experimental partition coefficients are more consistent with the experimental profiles, compared to those calculated using the equilibrium partition coefficients.     

Effect of high salt concentrations on water structure

The characteristic tetrahedral structure of water is known to be disrupted by changes in pressure and temperature. It has been suggested that ions in solution may have a similar perturbing effect. Here we use neutron diffraction to compare the effects of applied pressure and high salt concentrations on the hydrogen-bonded network of water. We find that the ions induce a change in structure equivalent to the application of high pressures, and that the size of the effect is ion-specific. Ionic concentrations of a few moles per litre have equivalent pressures that can exceed a thousand atmospheres. We propose that these changes may be understood in terms of the partial molar volume of the ions, relative to those of water molecules. The equivalent induced pressure of a particular ion species is correlated with its efficacy in precipitating, or salting-out, proteins from solution.     

盐胁迫对不同苦瓜品种萌发及幼苗生长的影响

对海南常种的四个苦瓜品种（琼1号苦瓜、杂交一代金绿大肉苦瓜、一代交配槟城苦瓜和广研杂交苦瓜），在不同盐浓度下进行盐胁迫。结果表明广研杂交苦瓜在种子萌发及幼苗生长方面比其它三个品种耐盐。同时，当盐浓度为150mmol/L，各品种种子几乎不能萌发；当盐浓度为100mmol/L时，种子虽能萌发，但幼苗不能成活。     

种植红豆草和春小麦对土壤可溶性盐分运移的影响

通过田间试验，测定了种植红豆草（Onobrychis viciaefolia）和春小麦（Triticum aestivum）对土壤可溶性盐分运移的影响．结果表明：不同绿色覆盖方式对0～20cm土层都具有明显的抑盐效应，随着地上生物量的增加，土壤表层的可溶性盐分下降幅度达16．4％～30．5％；在生育期内，红豆草的抑盐效应（0～20cm土层）较小麦强，红豆草使0～80cm土层脱盐率达23．4％，而小麦使0～80cm土层积盐率达14．2％；单作小麦收获后的空闲地．土壤表层盐分上升速度较裸地快．     

盐胁迫对甜高粱幼苗抗氧化酶活性的影响

研究了不同浓度NaCl溶液(含量0、50、100、150 mmol/L)处理对4种甜高粱幼苗超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性以及脂质过氧化产物丙二醛含量的影响。结果表明,与对照相比(即NaCl浓度为0),50 mmol/L NaCl处理显著增加了SOD、POD和CAT活性,而100和150 mmol/L NaCl处理则抑制了3种抗氧化酶活性。NaCl胁迫导致了脂质过氧化发生,具体表现为随着NaCl处理的浓度增加,丙二醛也增加。4种供试甜高粱对NaCl胁迫的应答有差异,其中辽甜1号在所有供试浓度的NaCl胁迫下,3种抗氧化酶活性均高于其他3个品种,而丙二醛含量最低,表明辽甜1号对NaCl的耐受性是最强的。