11-苄硒基十一羧酸铵盐的双重刺激响应性质

合成了一种对氧化还原(Redox)和CO_2/N_2具有双重刺激响应的表面活性剂11-苄硒基十一羧酸铵盐(BSeUA),分别利用傅里叶红外光谱、核磁共振和电喷雾质谱等手段研究了BSeUA在Redox和CO_2/N_2刺激响应前后的分子结构变化特征。结果表明,在过氧化氢和水合肼交替作用下,BSeUA分子中二价硒醚基团(-Se-)与相应的四价硒亚砜基团(-Se=O)之间可以氧化还原可逆互变,在CO_2和N_2交替作用下,BSeUA分子中羧酸根(-COO-)与相应的羧酸(-COOH)之间可以可逆互变,从而实现BSeUA对Redox和CO_2/N_2具有双重刺激响应。分别在Redox和CO_2/N_2刺激作用下,由BSeUA稳定的乳液可以在破乳和再乳化2种状态下开关可逆循环至少5次,且乳液粒径和稳定性未发生明显变化。     

富硒低钠盐中碘含量的测定

目的探讨富硒低钠加碘盐中碘含量的测定方法。方法通过不同的实验条件,优化国标GB/T13025.7-2012《制盐工业通用试验方法碘的测定》中氧化还原滴定法中的试剂用量,检测出富硒低钠加碘盐中的碘含量。结果改变碘化钾溶液量、淀粉溶液量、磷酸-草酸溶液量均无法测定富硒低钠盐中的碘含量;只有当次氯酸钠溶液用量≥5mL时,加入碘化钾溶液,才可以使富硒低钠加碘盐溶液显色,然后通过实验确定次氯酸钠的最佳用量,再滴定测定碘含量。结论富硒低钠加碘盐中含有还原性物质,测定其碘含量需加大次氯酸钠溶液的用量。     

Milk from cows fed a diet with a high forage:concentrate ratio improves inflammatory state,oxidative stress,and mitochondrial function in rats

Excessive energy intake may evoke complex biochemical processes characterized by inflammation, oxidative stress, and impairment of mitochondrial function that represent the main factors underlying noncommunicable diseases. Because cow milk is widely used for human nutrition and in food industry processing, the nutritional quality of milk is of special interest with respect to human health. In our study, we analyzed milk produced by dairy cows fed a diet characterized by a high forage:concentrate ratio (high forage milk, HFM). In view of the low n-6:n-3 ratio and high content of conjugated linoleic acid of HFM, we studied the effects of this milk on lipid metabolism, inflammation, mitochondrial function, and oxidative stress in a rat model. To this end, we supplemented for 4 wk the diet of male Wistar rats with HFM and with an isocaloric amount (82 kJ, 22 mL/d) of milk obtained from cows fed a diet with low forage:concentrate ratio, and analyzed the metabolic parameters of the animals. Our results indicate that HFM may positively affect lipid metabolism, leptin:adiponectin ratio, inflammation, mitochondrial function, and oxidative stress, providing the first evidence of the beneficial effects of HFM on rat metabolism.     

Electrolyte flow optimization and performance metrics analysis of vanadium redox flow battery for large-scale stationary energy storage

Vanadium redox flow battery (VRFB) is the best choice for large-scale stationary energy storage, but its low energy density affects its overall performance and restricts its development. In order to improve the performance of VRFB, a new type of spiral flow field is proposed, and a multi-physics coupling model and performance metrics evaluation system are established to explore the electrolyte distribution characteristics. The results show that the new spiral flow field can effectively improve the uniformity of electrolyte flow and alleviate the phenomenon of local concentration polarization as compared with the traditional serpentine flow field and parallel flow field. Due to the long flow channel and large pressure drop, the system efficiency is low. However, coulombic efficiency, voltage efficiency and energy efficiency are significantly better than the traditional flow fields. Therefore, the novel flow field has obvious advantages in the application of small stacks.     

Balancing the specific surface area and mass diffusion property of electrospun carbon fibers to enhance the cell performance of vanadium redox flow battery

Electrospun carbon fibers are featured with abundant electroactive sites but large mass transport resistances as the electrodes for vanadium redox flow battery. To lower mass transport resistances while maintaining large specific areas, electrospun carbon fibers with different structural properties, including pore size and pore distribution, are prepared by varying precursor concentrations. Increasing the polyacrylonitrile concentration from 9 wt% to 18 wt% results in carbonized fibers with an average fiber diameter ranging from 0.28 μm to 1.82 μm. The median pore diameter, in the meantime, almost linearly increases from 1.32 μm to 9.05 μm while maintaining the porosity of higher than 82%. The subsequent electroactivity evaluation and full battery testing demonstrate that the mass transport of vanadium ions through the electrode with larger fiber diameters are significantly improved but not scarifying the electrochemical activity. It is shown that the flow battery with these electrodes obtains an energy efficiency of 79% and electrolyte utilization of 74% at 300 mA cm⁻². Hence, all these results eliminate the concern of mass transport when applying electrospun carbon fibers as the electrodes for redox flow batteries and guide the future development of electrospun carbon fibers.     

Robust proton exchange membrane for vanadium redox flow batteries reinforced by silica-encapsulated nanocellulose

High ion selectivity and mechanical strength are critical properties for proton exchange membranes in vanadium redox flow batteries. In this work, a novel sulfonated poly(ether sulfone) hybrid membrane reinforced by core-shell structured nanocellulose (CNC-SPES) is prepared to obtain a robust and high-performance proton exchange membrane for vanadium redox flow batteries. Membrane morphology, proton conductivity, vanadium permeability and tensile strength are investigated. Single cell tests at a range of 40–140 mA cm⁻² are carried out. The performance of the sulfonated poly(ether sulfone) membrane reinforced by pristine nanocellulose (NC-SPES) and Nafion® 212 membranes are also studied for comparison. The results show that, with the incorporation of silica-encapsulated nanocellulose, the membrane exhibits outstanding mechanical strength of 54.5 MPa and high energy efficiency above 82% at 100 mA cm⁻², which is stable during 200 charge-discharge cycles.     

复合添加剂对钒电池正极电解液性能的影响

为了提高钒电池电解液的性能，选取了3种复合添加剂，研究了复合添加剂对钒电池正极电解液稳定性和电化学性能的影响。利用电化学方法制备了2 mol/L的全钒液流电池正极5价钒离子电解液，采用临界胶束浓度法得到复合添加剂的配比为：1% KHSO₄+3 mmol/L SDBS（十二烷基苯磺酸钠）、1% KHSO₄+2 mmol/L D-山梨醇、1% KHSO₄+2 mmol/L CTAB（十六烷基三甲基溴化铵），并考察添加剂加入电解液后的稳定性与电化学性能。通过XRD分析手段，对电解液沉淀物的成分进行了表征。研究表明：添加剂的加入，并不会引起钒离子价态的变化，1% KHSO₄+2 mmol/L CTAB加入后，电解液峰电位差减小12 mV，峰电流增加9.8 mA，说明CTAB与KHSO₄在合适配比下，能够有效提高正极电解液的稳定性及可逆性，添加剂的引入并未引起电解液沉淀物的物相组成变化，电解液性能显著提高。     

Li-doping stabilized P2-Li0.2Na1.0Mn0.8O2 sodium ion cathode with oxygen redox activity

The discovery of the oxygen chemistry phenomenon reveals bright future toward new sustainable layered Na-based transitional oxides. However, the poor capacity retention problem of the cathode has hindered the development of sodium ion batteries (SIBs). In this work, a new Li-doped compound Li_0.2Na_1.0Mn_0.8O₂ is proposed, which demonstrates refined cycling durability with 51.6% after 100 cycles at 50 mA g⁻¹, superior than Na_1.2Mn_0.8O₂ with only one cycle. Then in situ X-ray diffraction (XRD) and density function theory (DFT) are employed to explore the lattice distortion and confirm stable lattice framework introduced by Li atoms with eliminated P2-O2 phase transition upon cycling, guaranteeing outstanding electrochemically stable performance. In addition, Li_0.2Na_1.0Mn_0.8O₂ demonstrates activation of Mn as well as O chemistry redox in the lattice, detected by ex situ electronic paramagnetic resonance spectroscopy (EPR) as well as in situ Raman, which indicate not only Na-deficient Mn-based layered oxide but also Na-rich Mn-based compound can represent oxygen redox.