The corrosion resistance of 316 stainless steel (316SS) in molten KCl-MgCl2 salts was studied through static immersion corrosion at high temperatures. Below 600 °C, the corrosion rate of 316SS ...increased slowly with increasing temperature. When the salt temperature rises to 700 °C, the corrosion rate of 316SS increases dramatically. The corrosion of 316SS is mainly due to the selective dissolution of Cr and Fe at high temperatures. The impurities in molten KCl-MgCl2 salts could accelerate the dissolution of Cr and Fe atoms in the grain boundary of 316SS, and purification treatment can reduce the corrosivity of KCl-MgCl2 salts. Under the experimental conditions, the diffusion rate of Cr/Fe in 316SS changed more with temperature than the reaction rate of salt impurities with Cr/Fe.
PAN fibers were irradiated by electron-beam at room temperature in air. The micro-void structure transformation and properties of irradiated PAN fibers were characterized using gel permeation ...chromatograph, small angle X-ray scattering, differential scanning calorimetry, thermogravimetric analysis and tensile strength. The cross-linking occurred dominantly, and the stable polymer network formed. The gel fraction got saturated at 200 kGy and did not further increase due to the oxidation degradation. The lateral size of micro-voids and the dose were negatively correlated while the length and misorientation of micro-voids expanded with dose increased (61.73 nm–201.06 nm, 7.79°–11.86°). The intense heat release of cyclization reaction was efficiently relieved by irradiation. Meanwhile, carbon yield at 800 °C also increased from 43% to 55% after irradiation at 200 kGy, which increased by 25% compared with original PAN fibers. This study can prefer irradiation conditions to improve PAN based carbon fiber property.
•SAXS was firstly used to study the micro-voids structure of irradiated PAN fibers.•Transformation of micro-voids led to a decline in mechanical properties.•Crosslinking caused a reduction in the lateral size of micro-voids for PAN fibers.•Carbon yield at 800 °C increased to 54.9% after irradiation.
The structural changes of cassava starch granules were studied by scanning electron microscope (SEM), X-ray diffraction (XRD), and differential scanning calorimeter after starch granules were ...hydrolyzed by a mixture of α-amylase and glucoamylase. The surface of starch granules was porous after hydrolysis treatment. Enzymatic erosion occurred mainly at the surface for cassava starch. The BET-specific surface area of hydrolyzed cassava starch improved 10.7 times compared with that of native starch. The powder XRD intensity of hydrolyzed starch was higher than that of native starch. The crystallinity in the hydrolyzed cassava starch increased due to hydrolysis. Compound enzymes could hydrolyze cassava starch granules at sub-gelatinization temperature, and could produce porous starch.
Applications of ionic liquids (ILs) in electrified interfaces and electrochemical systems require insight into the molecular-level structure and properties of the interfacial ILs. Using atomistic ...molecular dynamics (MD) simulations, we show here that a new double-layer stacking formation of the BmimPF6 IL can be triggered by the surface negative charge. We also found that the double-layer formation induced by the surface charge thoroughly extended into the bulk phase, implying a strong unscreened ion effect in our IL system. Further study indicated that the double-layer formation in the bulk phase was due to a rapid structural transition. Different IL formations, including the conventional adsorption layer and the double-layer formation, can be achieved in sequence by increasing the surface negative charge. Moreover, the diffusion ability of the new double-layer formation in the bulk phase is much lower when compared to that observed in its original uncharged condition. The structure and properties of the ILs formation may be attributed to the tail−tail aggregation hypothesis of the nonpolar domain in the IL.
It has been reported that folic acid supplementation before and/or during pregnancy could reduce the risk of congenital heart defects (CHDs). However, the results from limited epidemiologic studies ...have been inconclusive. We investigated the associations between maternal folic acid supplementation, dietary folate intake, and the risk of CHDs.
A birth cohort study was conducted in 2010-2012 at the Gansu Provincial Maternity & Child Care Hospital in Lanzhou, China. After exclusion of stillbirths and multiple births, a total of 94 births were identified with congenital heart defects, and 9,993 births without any birth defects. Unconditional logistic regression was used to estimate the associations.
Compared to non-users, folic acid supplement users before pregnancy had a reduced risk of overall CHDs (OR: 0.42, 95% CI: 0.21-0.86, Ptrend = 0.025) after adjusted for potential confounders. A protective effect was observed for certain subtypes of CHDs (OR: 0.37, 95% CI: 0.16-0.85 for malformation of great arteries; 0.26, 0.10-0.68 for malformation of cardiac septa; 0.34, 0.13-0.93 for Atrial septal defect). A similar protective effect was also seen for multiple CHDs (OR: 0.49, 95% CI: 0.26-0.93, Ptrend = 0.004). Compared with the middle quartiles of dietary folate intake, lower dietary folate intake (<149.88 μg/day) during pregnancy were associated with increased risk of overall CHDs (OR: 1.63, 95% CI: 1.01-2.62) and patent ductus arteriosus (OR: 1.85, 95% CI: 1.03-3.32). Women who were non-user folic acid supplement and lower dietary folate intake have almost 2-fold increased CHDs risk in their offspring.
Our study suggested that folic acid supplementation before pregnancy was associated with a reduced risk of CHDs, lower dietary folate intake during pregnancy was associated with increased risk. The observed associations varied by CHD subtypes. A synergistic effect of dietary folate intake and folic acid supplementation was also observed.
Waterproof breathable functional membranes have broad application prospects in the field of outdoors textiles. The fluorine-containing microporous membranes of the mainstream functional products ...easily cause harm to the environment, and thus, the fluorine-free environmental nanofibrous membranes are an important development direction for functional membranes. In this subject, the electrospun polyacrylonitrile nanofibrous membranes were first hydrophobically modified by amino functional modified polysiloxane (AMP), followed by in situ cross-linking modified with 4, 4'-methyl diphenylene diisocyanate (MDI). The fluorine-free modification by AMP altered the surface of the membranes from hydrophilic to hydrophobic, and greatly improved the waterproof properties with the hydrostatic pressure reaching to 87.6 kPa. In addition, the formation of bonding points and the in situ preparation of polyuria through the reaction between the isocyanate in MDI and the amino group in AMP, could improve the mechanical properties effectively. When using AMP with the concentration of 1 wt% and MDI with the concentration of 2 wt%, the relatively good comprehensive performance was obtained with good water resistance (93.8 kPa), modest vapor permeability (4.7 kg m
d
) and air permeability (12.7 mm/s). Based on these testing data, the modified nanofibrous membranes had excellent waterproof and breathable properties, which has future potential in outdoor sports apparel.
This study prepared 4,4-diaminodiphenylmethane (DDM)-functionalized graphene oxide (GO)@silica dioxide (SiO2) nano-composites through amidation reaction and low-temperature precipitation. The ...resulting modified GO, that was DDM−GO@SiO2. The study found that DDM−GO@SiO2 showed good dispersion and compatibility with thermoplastic polyurethane (TPU) substrates. Compared with pure TPU, the tensile strength of the TPU composites increased by 41% to 94.6 MPa at only 0.5 wt% DDM−GO@SiO2. In addition, even when a small amount of DDM−GO@SiO2 was added, the UV absorption of TPU composites increased significantly, TPU composites can achieve a UV shielding efficiency of 95.21% in the UV-A region. These results show that this type of material holds great promise for the preparation of functional coatings and film materials with high strength and weather resistance.
Confinement can induce unusual behavior in the properties of matter. Using atomistic molecular dynamics simulations, we report here a liquid-to-solid transition of a bilayer of ionic liquid ...1,3-dimethylimidazolium chloride (DmimCl) confined between graphite walls in order to mimic the phase transition of an ionic liquid confined to hydrophobic nanospace. It was found that the ionic liquid bilayer undergoes a clear and drastic phase transition at a wall distance of about 1.1 nm, forming a new high-melting-point solid phase with different hydrogen bonding networks. In the new phase, each cation is surrounded by the three nearest-neighbor anions, and each anion is also encircled by the three nearest-neighbor cations. Strong π−π stacking interactions are found between the cations of the bilayer solid. The anions can be formed into a hexagonal ring around the cations. The new bilayer solid is a high-melting-point crystal possessing a melting point of 825−850 K, which is higher than that of the bulk crystal by more than 400 K.
The synchrotron radiation X-ray was used both as the irradiation source and testing tool for the PVDF membranes in-situ. The structural evolution of the PVDF membranes irradiated by the synchrotron ...radiation X-ray was analyzed by in-situ small angle X-ray scattering (SAXS)/wide angle X-ray scattering (WAXS) and ex-situ (ESR, FTIR and XRD) characterization methods. The alkyl radicals and carbon-carbon double bonds appeared in the irradiated PVDF membranes due to the irradiation effect, which confirmed that PVDF membranes first cracked, followed by cross-linked, during irradiation. The disappearance of the scattering peak at q = 0.05 Å−1 indicated that the synchrotron radiation X-ray destroyed the long periodic structure. The X-ray irradiation destroyed the crystalline region of the irradiated PVDF membranes, thus, leading to a decline in the crystallinity. Thus, overall, the in-situ irradiation and analysis could effectively monitor the structural evolution of the PVDF membranes during the radiation process and reduce the influence of time intervals between irradiation and measurement.
•Synchrotron radiation X-ray is used as the radiation source and detection method.•2.SAXS/WAXD were firstly monitored the internal structure evolution of PVDF in situ.•3.Synchrotron radiation X-ray destroyed the long periodic structure of irradiated PVDF.•4.In-situ radiation and analysis could effectively monitor structure evolution real time.
Intermediate temperature NaCl–AlCl3-based Al-ion batteries are considered as a promising stationary energy storage system due to their low cost, high safety, etc. However, such a cheap electrolyte ...has a critical feature, i.e., strong corrosion, which results in the short cycle life of the conventional Al-metal anode and also limits the development of the NaCl–AlCl3-based Al-ion batteries. A noncorrosive electrolyte may be a good choice for addressing the above challenge, while it is difficult to obtain the electrolyte that has advantages of both noncorrosion and low cost. Therefore, here, we report a Ga-metal anode in the affordable NaCl–AlCl3 electrolyte for constructing a long-life stationary Al-ion energy storage system. This featured liquid metal anode shows good alloying and dealloying processes between metallic Ga and Al, as well as renders superior stability of the interface between the electrolyte and the anode (e.g., smoothly running for over 580 h at 2 mA cm–2). No-corrosion and no-pulverization problems appear in this novel liquid/liquid interface. Those advantages demonstrate that the liquid Ga-metal anode has a great promise for the improvement of the NaCl–AlCl3-based Al-ion batteries for large-scale stationary energy storage applications.
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