一种植物油中苯并（a）芘含量测定的固相萃取前处理方法

为了建立一种准确性高、成本低的植物油中苯并(a)芘测定的样品前处理方法，基于GB 5009.7—2016以自制氧化铝柱为固相萃取柱，采用单因素试验对称样量、洗脱剂量、洗脱流速、吸附剂存放时间、吸附剂量这5个影响植物油中苯并（a）芘洗脱的因素进行研究，优化前处理条件，并对测定方法进行考察。结果表明：优化的前处理条件为称样量0.100 0 g、洗脱剂量120 mL、吸附剂（氧化铝）量22 g、洗脱流速1滴/2 s、吸附剂存放时间少于12周；方法检出限为0.2 μg/L，样品加标回收率为94.23%～100.00%，RSD为1.20%～7.36%；同一样品测定结果与SGS测定值接近，相对平均偏差为2.36%～3.50%。说明本试验方法测定结果准确，可应用于油脂企业植物油中痕量苯并（a）芘的测定。     

Synthesis and characterization of SrFeOx hetero-film resistance-switching device with low operation voltage

As a critical topological phase transition material, SrFeO_x could play an essential role in the field of resistive memory. How to implement resistance-switching more softly and ensure the stability of materials has always been a relevant research hotspot. Regulating the oxygen environment during the deposition process of the films can effectively control the stoichiometry of the functional layer and then improve the resistance-switching characteristics of the device. In this paper, a SrFeO_x hetero-film was prepared by oxygen pretreatment on the SrRuO₃ surface before SrFeO_x deposition, and the as-assembled micrometer-scale device exhibits a low set operating voltage of 0.6 V and favorable cycling characteristics. The SrFeO_x hetero-film reveals a vertical brownmillerite superlattice-like structure with ～20 nm perovskite buffer layer, which benefits the connection and rupture of conductive filament. Additionally, XPS and UV–vis were used to analyze the bonding energy and band gap of SrFeO_x hetero-film, and offers the experimental basis for the explanation of the conductive mechanism. Therefore, the device based on SrFeO_x hetero-film with low operation voltage provides a reference for low power consumption research on topological phase transition material.     

碳酸钠碱性介质氧脱木素促进火炬松酶解糖化的研究

分别采用硫酸盐法（KP）和绿液法（GL）蒸煮火炬松，并以碳酸钠为碱性介质进行氧脱木素，所得浆料分别标记为KP-OC浆和GL-OC浆，分析了这两种浆料的化学组分，并对这两种浆料进行酶解以提取可发酵单糖。结果显示，在120℃氧脱木素4 h所得的KP-OC浆和GL-OC浆的木素脱出率均明显优于相近条件下以氢氧化钠为碱性介质且脱木素1 h的浆料。对于GL-OC浆和KP-OC浆，当酶用量为10 FPU/g时，酶解单糖得率、总单糖提取率最高分别可达73.2%和95.8%、72.4%和75.7%，均优于相近条件下以氢氧化钠为碱性介质氧脱木素的浆料。     

Enzymolysis reaction kinetics and thermodynamics of rapeseed protein with sequential dual‐frequency ultrasound pretreatment

We evaluated the effect of sequential dual‐frequency ultrasound (SDFU) pretreatments on rapeseed protein enzymolysis, using alcalase as a model enzyme. Hydrolysed protein concentrations, enzymolysis kinetics and thermodynamic parameters were investigated. The results showed that the hydrolysed rapeseed protein concentration following SDFU pretreatments was higher compared to that of the control for up to 75 min of enzymolysis at various substrate concentrations of 5–25 g L^?1; both control and SDFU pretreatment groups showed first‐order reaction kinetics. Compared to the control, the Michaelis–Menten constant (K_M) value decreased remarkably by 17.61%, while an increase in the binding frequency between enzyme and substrate (K_A) by 10.47% was observed. The thermodynamic parameters, enthalpy, entropy and activation energy were reduced in the SDFU pretreatment group compared to the control by 31.78%, 18.0% and 29.56%, respectively. SDFU pretreatment showed little effect on Gibbs free energy at the various temperatures studied.     

真空油炸马铃薯脆片预处理工艺优化

为优化马铃薯脆片的预处理工艺,采用单因素和响应面试验,以破碎力、含油量、L*值、感官评分、综合评分和电子鼻检测挥发性成分为指标,对实验数据进行主成分分析。结果表明:不同的预处理方式对马铃薯脆片的破碎力、感官评价和综合评分有显著影响(p0.05)。主成分分析共提取5个主成分,前3个主成分总贡献率大于85%,说明提取3个主成分能够全面反映马铃薯脆片的品质信息,决定第1主成分的指标主要是感官评价和综合评分,决定第2主成分的是破碎力和含油量;决定第3主成分的是L*值和含油量。以主成分分析得到的规范化综合得分为响应值建立的二次多项式回归模型回归效果极显著(p0.01,R~2=0.9604)。确定最佳工艺参数为漂烫温度91℃、漂烫时间4 min、切片厚度4 mm和冷冻时间3 h,在此条件得到规范化综合评分0.9572,与预测值(0.9453)相接近,表明以主成分分析得到的规范化综合评分为响应值建立的回归模型具有良好的预测能力。     

不同模式超声预处理对莲子蛋白酶解物及其结构的影响

超声波参数中,超声频率是影响蛋白酶解的主要因素。因此,本实验以不同模式超声频率下得到的莲子蛋白酶解物为研究对象,首先对不同模式超声进行优化,以血管紧张素转化酶(angiotensin converting enzyme,ACE)抑制率和水解度为指标,得出了不同模式下的最优频率参数:单频率超声20 kHz、双频率组合20/35 kHz、三频率超声组合20/35/50 kHz。然后采用表面疏水性、氨基酸分析及内源性荧光光谱等表征不同模式的超声预处理对莲子蛋白酶解物及结构特征影响。结果显示:随着超声频率组合增多,表面疏水性越来越大,疏水性氨基酸含量增多,主要是由于超声预处理使蛋白结构展开,使最初被掩埋在蛋白分子内部的疏水基团暴露。通过荧光光谱发现,超声预处理提高了莲子蛋白的荧光强度,且荧光强度顺序为三频双频单频;同时,莲子蛋白酶解物λmax发生轻微的红移现象。上述结果对于莲子蛋白酶解及ACE抑制肽的制备至关重要。     

复合保鲜液对鲜切荸荠的保鲜效果

根据鲜切荸荠在储藏过程中容易氧化变质的现象,研究一种复合保鲜液对鲜切荸荠进行保鲜;利用食盐、白糖、白醋等溶液对鲜切荸荠进行浸泡预处理后再进行包装,置于室温条件(25℃)下储藏;分别测定了特定时间内鲜切荸荠的颜色、硬度、失重率、电导率、多酚氧化酶活性、可溶性固形物、总酚含量等参数,并对气味、胀袋情况等进行了感官评价;同时在单因素试验的基础上进行正交试验。结果表明:最佳工艺组合为食盐浓度80g/L+白糖浓度3g/L+白醋浓度100g/L+浸泡时间15min,与对照组相比,使鲜切荸荠保鲜期延长了6d以上。     

Phosphoric Acid-assisted Pretreatment Strategy for the Rational Synthesis of Lignin-derived Hierarchical Porous Carbon Toward High-performance Supercapacitors

In this article, a facile two-step activation method, coupled with phosphoric acid (H₃PO₄)-assisted pretreatment and followed KOH activation, was reported for constructing hierarchical porous carbon (HPC) materials derived from lignin. The introduction of H₃PO₄, cross-linked with lignin sources generated phosphate (and/or polyphosphate) ester groups throughout the lignin structure, which endowed the pre-activated intermediate char (IC) with a hierarchical porous structure. Such phosphate esters contributed to the multi-scale pore structure within the pre-activated IC, which was beneficial for the uniform distribution and impregnation of subsequent KOH activators, thus leading to the formation of HPC materials. The as-prepared HPC exhibited a large specific surface area (SSA) of 1345.1 m²/g, which ensures the accessibility of the ion diffusion pathways. The supercapacitors integrated with HPC delivered a high specific capacitance of 241 F/g (in a three-electrode system) and outstanding rate capability with an 80.9% capacitance retention from 0.5 A/g to an ultra-high current density of 50 A/g.     

燃煤电厂软土层地基预处理方案和施工探究

本文阐述了预处理的重要性,揭示了当前施工中存在的问题,并对软土层地基处理提出了具体的方案。     

功能性海带面包生产工艺的研究

该研究将海带进行处理后添加到面包中,通过对生产工艺进行研究,以期得到功能性的海带面包。以面包感官评价得分为考察指标,考察高压蒸煮温度、蒸煮时间、海带粒径3个因素对面包品质的影响,确定海带最佳预处理工艺条件为:高压蒸煮温度125℃、蒸煮时间20 min、海带粉碎粒度40目<φ<60目;采用正交试验分析法,确定海带面包的最佳生产配方为:食盐添加量为1.5%、海带粉添加量为8%、酵母添加量为2.0%、改良剂添加量为0.8%。此条件下,海带面包的体积膨松,组织气孔细密,口感柔软,具有海带清香味。