Urea–formaldehyde resin prepared with concentrated formaldehyde

The characteristics of UF resin prepared with concentrated formaldehyde were studied in this paper. With the molar ratio F/U = 1.1, the UF resin prepared with concentrated formaldehyde showed better mechanical properties than that with formalin. The ¹³C-NMR and FTIR results indicated that there were more methylene groups, ether groups and urons in a UF resin system prepared with concentrated formaldehyde than those in a normal UF resin. The differential scanning calorimetry and DMA results showed that the curing temperature of UF resin with concentrated formaldehyde was lower than that of a normal UF resin. UF resin with concentrated formaldehyde showed worse thermal stability and higher thermal decomposition temperature.     

水质变化时垢层对铸铁腐蚀的影响作用

通过对水质变化时铸铁腐蚀速率与铁释放的对比,研究垢层对铸铁腐蚀的影响作用。结果表明,改变水的硬度和拉森指数(LR),对铸铁的腐蚀速率与铁释放均有明显影响;低硬度水质条件下形成的管垢以较易分解和转化的Fe(OH)_3为主,而较为稳定的Fe_3O_4含量较低,在硬度或LR改变时,管垢破坏严重,铸铁基底腐蚀加剧;高硬度水质下形成的管垢较为致密,表面覆盖大量的CaCO_3,且含有较多Fe_3O_4和FeOOH,管垢整体结构稳定,在硬度或LR改变时,能抑制铸铁基底的进一步腐蚀。     

Affinity‐tuned peroxidase‐like activity of hydrogel‐supported Fe3O4 nanozyme through alteration of crosslinking concentration

In this work, we evaluated the effect of crosslinking concentration on the affinity of poly (2‐acrylamido‐2‐methyl‐1‐propansulfonic acid) (PAMPS) hydrogel‐supported Fe₃O₄ nanozyme towards substrates (tetramethylbenzidine (TMB) and H₂O₂). The peroxidase‐like catalytic activity of PAMPS/Fe₃O₄ nanozyme was discussed with respect to crosslinking concentration of PAMPS hydrogel for the oxidation of TMB in the presence of H₂O₂ at room temperature. High catalytic activity was achieved due to good dispersion of Fe₃O₄ nanozyme in the hydrogel network and strong affinity of PAMPS hydrogel‐supported Fe₃O₄ nanozyme towards substrates. The affinity between the hydrogel‐supported Fe₃O₄ nanozyme and substrates can be improved by regulating the crosslinking concentration of PAMPS hydrogel without other trenchant experimental conditions. In addition, the result indicated that H₂O₂ can be detected even at a concentration as low as 1.5 × 10^?6 mol L^?1 with a linear detection range of 1.5–9.8 × 10^?6 mol L^?1. Such investigations not only showed a new approach to improve the affinity and peroxidase‐like activity of Fe₃O₄ nanozyme, but also verified its potential application in bio‐detection and environmental chemistry. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43065.     

Amphiphilic acrylate copolymer fatliquor for ecological leather: Influence of molecular weight on performances

With increasing demand for ecological leather, ecological fatliquors with good comprehensive properties are getting more and more attention. The amphiphilic acrylate copolymer containing both hydrophilic (carboxyl) and hydrophobic (long alkyl) groups is one of the main alternatives to conventional fatliquors. In this paper, a series of poly(acrylic acid‐co‐stearyl acrylate) with different relative molecular weights were prepared, and the influence of the molecular weight on their application performances were evaluated. The results show that lower relative molecular weight of copolymers is conducive to the penetration and absorption, and it improves the softness and fiber separation of leather. When the number average molecular weight (M_n) of copolymer is higher than 25,000, its penetration and absorption become worse and the resulting leather feels hard. In addition, the amphiphilic acrylate copolymers can impart excellent oxidation resistance and transference resistance to leather, which is a considerable improvement over the conventionally retanned and fatliquored leather. The copolymer has great penetration and absorption ability when M_n is within the range of 9,000–15,000, and it gives leather excellent integrated properties, such as filling, softness, mechanical strength, extraction resistance, and oxidation resistance, which can meet requirements of ecological leather. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43440.     

Dietary Arachidonic Acid Has a Time-Dependent Differential Impact on Adipogenesis Modulated via COX and LOX Pathways in Grass Carp Ctenopharyngodon idellus

In this study, we explored the function of arachidonic acid (ARA) in adipogenesis in the grass carp (Ctenopharyngodon idellus) using in vivo and in vitro models. An 8‐week feeding trial was performed using three isonitrogenous and isoenergetic purified diets: ARA‐free, ARA, and ARA + acetylsalicylic acid [ASA, a cyclooxygenase (COX) inhibitor]. Fish were sampled after 4 and 8 weeks of feeding. Results showed that ARA‐fed fish had a significantly lower intraperitoneal fat index (IPFI) and smaller adipocytes; these decreases were reversed by ASA after 8 weeks of feeding. Nevertheless, at week 4, the IPFI and adipocyte size were higher in the ARA group, and they were comparable to those of fish fed ARA + ASA. To further investigate the influence of ARA on adipocyte differentiation, confluent pre‐adipocytes of grass carp were incubated with ARA for 3 days. This in vitro experiment demonstrated that ARA promoted adipogenesis in a dose‐dependent manner. Pre‐treatment with the lipoxygenase (LOX) inhibitor nordihydroguaiaretic acid attenuated the pro‐adipogenic function of ARA. However, after treatment with ARA for 8 days, adipocytes had a lower lipid content than cells treated with oleic acid, and ASA could suppress this effect. We thus revealed the dual function of ARA in adipogenesis in grass carp. The LOX pathway may play a key role in pro‐adipogenesis after short‐term treatment with ARA, whereas the COX pathway is possibly responsible for the inhibition of adipogenesis after long‐term treatment.     

Preparation of glucose‐sensitive and fluorescence micelles via a combination of photoinitiated polymerization and chemoenzymatic transesterification for the controlled release of insulin

Glucose‐sensitive and fluorescence copolymer micelles were designed and prepared via a combination of photoinitiated polymerization and enzymatic transesterification. The water‐soluble photoinitiator and emulsifier 2‐oxooctanoic acid self‐polymerized dimer molecules under UV irradiation were characterized by mass spectrometry. The fluorescence dye (9‐anthracene alcohol) and biocompatible hydrophilic chains [poly(ethylene glycol)] were introduced to the polymer chains during the photopolymerization and enzymatic transesterification processes. The as‐prepared copolymers were confirmed by ¹H‐NMR spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and dynamic light scattering. The resulting copolymers exhibited excellent glucose sensitivity and stability against protein. The optical fluorescence properties of the copolymer micelles were investigated with fluorescence spectrophotometry, fluorescence microscopy, and confocal laser scanning microscopy. Because of the amphiphilic feature, the micelles could be self‐assembled and used to load insulin. The controlled release of insulin was evaluated and was triggered by glucose in vitro. This study provided a new strategy for fabricating functional carriers as self‐regulated insulin‐release systems. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43026.     

Spectral and Laser Properties of Yb:LuAG Transparent Ceramics Fabricated by Tape Casting Method

Yb³⁺‐doped LuAG laser ceramics with different Yb³⁺‐doping concentrations were successfully fabricated by nonaqueous tape casting method and vacuum sintering technology. XRD patterns and SEM morphologies of the ceramics were presented. The optical in‐line transmittance of the Yb‐doped LuAG ceramics was about 83% at 1030 nm. The fluorescence lifetime of annealed and unannealed ceramic samples was compared. From the spectroscopic properties, it can be seen that the ceramics had a large emission cross section of 2.9 × 10^?20 cm² with a FWHM of about 7.2 nm at 1030 nm. Under 100% population inversion, the maximum gain coefficient was estimated to be 12.4 cm^?1 at 1030 nm. With a fiber‐coupled diode laser as pump source, CW laser at 1030 nm was demonstrated and the maximum output power of 338.9 mW was achieved with a slop efficiency of 19%. A tuning range from 1028 to 1036 nm was obtained.     

Data‐driven mathematical modeling and global optimization framework for entire petrochemical planning operations

In this work we develop a novel modeling and global optimization‐based planning formulation, which predicts product yields and properties for all of the production units within a highly integrated refinery‐petrochemical complex. Distillation is modeled using swing‐cut theory, while data‐based nonlinear models are developed for other processing units. The parameters of the postulated models are globally optimized based on a large data set of daily production. Property indices in blending units are linearly additive and they are calculated on a weight or volume basis. Binary variables are introduced to denote unit and operation modes selection. The planning model is a large‐scale non‐convex mixed integer nonlinear optimization model, which is solved to ε‐global optimality. Computational results for multiple case studies indicate that we achieve a significant profit increase (37–65%) using the proposed data‐driven global optimization framework. Finally, a user‐friendly interface is presented which enables automated updating of demand, specification, and cost parameters. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3020–3040, 2016     

Electric Field Cycling Induced Large Electrostrain in Aged (K0.5Na0.5)NbO3–Cu Lead‐Free Piezoelectric Ceramics

In this work, we studied aging and fatigue behaviors of 1.0 mol%Cu‐modified (Na_0.5K_0.5)NbO₃ lead‐free ceramics with double‐loop‐like characteristic, and found an interesting result of electric field cycling induced large electrostrain in the aged samples. After the “aging” treatment, the hysteresis loop “closes” totally and constricts completely at zero electric field, accompanying with a large nonlinear electrostrain of about 0.26%. More interestingly, the electrostrain in the aged sample is sensitive to the field cycling, which is pushed to a higher level of 0.47% approaching that of some Pb‐based antiferroelectric materials. A microscopic model of the domain switching‐related electrostrain effect is proposed to explain the field cycling induced large electrostrain in the aged samples. It can be identified due to the weakening of intrinsic restoring force for reversing the switched domains, induced by the point defects (defect dipoles) migration aligning along field direction during cycling, evident by the gradually “opened” hysteresis loop with cycling.