Hydroquinone (HQ) and catechol (CC) are nearly identical toxic phenolic pollutants, challenging their simultaneous detection in waters. Herein, we report a stacked leaf-like ZnCo/N-PC@PMel electrode that selectively discriminates HQ from CC via preferential adsorption, enhancing HQ detection. Physicochemical characterization reveals a high specific surface area (621.05m²/g) and mesopores (3.9nm), and stacked leaf-like sheets of approximately 5 μm in length (SEM). Density functional theory (DFT) predicts substantially stronger adsorption affinity toward HQ over CC via hydrogen-bonding interactions with N-rich sites. Experimentally, the PMel/GCE, ZnCo/N-PC/GCE, and ZnCo/N-PC@PMel/GCE yielded peak potential separations (ΔEp) of 0.096, 0.112, and 0.104V, respectively. Although bare ZnCo/N-PC gives the largest ΔEp, it suppresses the CC current (68.04 μA) due to non-specific over-adsorption. In contrast, the hybrid achieves enhanced separation versus pristine PMel (0.104 > 0.096V) while delivering the highest CC current (76.41 μA), confirming that PMel introduces specific hydrogen-bonding sites and mitigates non-specific affinity. The sensor offers a linear range of 20–100μM and 100–400μM for both isomers, with detection limits (LODs) of 0.46μM (HQ) and 1.51μM (CC), and was successfully applied to simultaneous determination in real water samples. This DFT-guided design provides a rational paradigm for selective electrochemical monitoring of isomeric pollutants.

Heavy metal ions in food pose severe health risks, necessitating the development of simple and effective detection methods. In this study, we constructed an electrochemical sensor for simultaneous detection of Cd2+ and Pb2+ by modifying a glassy carbon electrode (GCE) with a composite of a cobalt-based zeolitic imidazolate framework (Co-ZIF) and carbonized litchi pericarp (LP) for the first time. The Co-ZIF@LP/GCE sensor leverages a synergistic "adsorption-conduction" mechanism: Co-ZIF provides abundant adsorption sites and catalytic activity, while LP enhances electrical conductivity and stability. Electrochemical performance was evaluated using cyclic voltammetry and electrochemical impedance spectroscopy. Key parameters including buffer pH, modification material ratio, drop-coating volume, deposition potential, deposition time, and quiet time were optimized via square wave stripping voltammetry. Under optimal conditions, the sensor exhibited high sensitivity toward Cd2+ and Pb2+, with wide linear ranges (1-10 mu M, 10-65 mu M) and low detection limits (0.028 mu M and 0.197 mu M). Practical application in rice and millet samples demonstrated good recovery and precision, confirming the method's reliability for detecting heavy metal ions in food samples.

Riboflavin plays a crucial role in human health and urgently calls for a simple, rapid and sensitive method for its detection in foods and pharmaceuticals. Herein, an electrochemical approach was established based on a carbonized flower shaped Zn-based Zeolitic Imidazolate Framework (C-ZIF-F) and the traditional Chinese medicine Bai Cao Shuang (BCS) composite modified glassy carbon electrode (GCE). The BSC mainly composed of carbon-based particles were well dispersed into C-ZIF-F to improve the conductivity and electrocatalytic activity. The C-ZIF-F/BCS/GCE sensor showed a great enhancement in responses for the electrochemical reaction of riboflavin. Under optimal conditions, the C-ZIF-F/BCS/GCE sensor demonstrates a linear range of 0.1-60 mu M with a low detection limit (LOD) of 0.083 mu M and a high sensitivity of 0.054 mu A mu M- 1 cm- 2. Moreover, this sensor demonstrates excellent reproducibility, long term stability and high selectivity during testing. This sensor was also successfully applied to the determination of riboflavin in vitamin B2 tablets, spinach and soymilk.

Heavy metal ions entering the human body via water and food pose significant health risks through long-term accumulation, underscoring the need for efficient and sensitive detection methods. However, electrochemical detection in complex matrices like grains remains relatively underexplored. Herein, a novel Zn, Co, N tri-doped porous carbon (ZnCo/N-PC) with a lamellar bird-nest-like structure was syntheziedby water-phase induced hydrothermal-pyrolysis approach. The resulting ZnCo/N-PC was combined with novel activated carbon for supercapacitors (NACS) to fabricate a ZnCo/N-PC@NACS/GCE electrochemical sensor. This design established a "high-speed channels + high loading capacity" sensing model, enabling highly sensitive simultaneous detection of Pb2+ and Cd2+. Density functional theory (DFT) calculations of binding energies elucidated the sensor's strong affinity for the target ions. Under optimal conditions, the sensor exhibited a wide linear range (0.1-80 mu M), low detection limits (0.078 mu M for Pb2+, 0.033 mu M for Cd2+), and excellent selectivity, reproducibility, and stability. The sensor was successfully applied for the rapid and simultaneous detection of Pb2+ and Cd2+ not only in real water samples (tap water, lake water) but also in complex-matrix grain samples (rice, millet), achieving recoveries of 90.8-106.6 % (water) and 88.5-115.8 % (grains), with relative standard deviations (RSDs) of 0.7-15.2 % (water) and 0.8-22.5 % (grains). This work provides robust technical support for environmental monitoring, food safety control, and public health protection.

High-performance electrode materials are crucial for electrochemical sensing of bioactive food compounds. We report an eco-friendly synthesis of coral-like cobalt/nitrogen-doped porous carbon (Co/N-PC) via hydrothermal-pyrolysis, integrated with MnO₂ to construct a Co/N-PC@MnO₂/GCE sensor for ultrasensitive luteolin (LU) detection. Synergy between the conductive Co/N-PC framework (electron transport) and MnO₂ nanoparticles (Mn2+/Mn3+/Mn4+ catalysis) delivers exceptional performance: dual linear ranges (0.01-1 μM; 1-100 μM) and a record-low 4 nM detection limit. Kinetic studies confirm the apparent electron transfer number (napp = 4) arises from MnO₂ mediation. The sensor demonstrated high practicality in complex floral teas (honeysuckle, chrysanthemum), achieving 77.2-103.6 % recoveries. This work provides both a sensitive, green LU detection method and elucidates a MnO₂ catalytic cycle mechanism, revealing new insights into LU's electrochemical pathway.

Elevated levels of methylglyoxal (MG) in the human body are linked to various metabolic disorders. Therefore, developing efficient methods for detecting MG in food and biological fluid is of significant importance. In this work, a high-catalytic-activity conductive copper-based metal-organic framework (Cu3(HHTP)2) was synthesized via a hydrothermal method, and a sensitive electrochemical sensor based on a glassy carbon electrode (GCE), denoted as Super-P/Cu3(HHTP)2/GCE, for monitoring methylglyoxal (MG) was constructed using a composite of Cu3(HHTP)2 and carbon black Super-P. Leveraging the catalytic activity of Cu3(HHTP)2 and the enhanced conductivity provided by Super-P, the sensor demonstrated a wide linear detection range (1-500 mu M) and a low detection limit (0.0275 mu M). Moreover, it was successfully applied to the determination of MG in milk, beer, urine, and human serum samples, achieving recoveries ranging from 91.7 % to 115.7 %. This work opens up new avenues for the development of innovative electroanalytical tools for MG monitoring in both food and biological fluid.

Herein, a stable and ultra-sensitive rutin electrochemical sensor was successfully developed. This sensor based on glassy carbon electrode (GCE) modified with C-GCS@ZIF-F/PL nanocomposite, which was made of thermally carbonized glucose (GCS) doped with flower-like ZIF (ZIF-F) and pencil lead (PL). The electrochemical response of rutin was considerably significant at C-GCS@ZIF-F/PL/GCE, demonstrating favorable conductivity and electrocatalytic properties for detection of rutin. Under optimal conditions, the linear range is 0.1-100 mu M, with a low detection limit (LOD) of 0.0054 mu M. It also exhibits excellent stability, reproducibility, as well as selectivity over common interfering ions such as Na+, + , uric acid, quercetin and riboflavin, etc. Meanwhile, the practical utility of developed sensor was evaluated in food samples including honey, orange, and buckwheat tea, achieving satisfactory recovery rates ranging from 98.2% to 101.7%. This paper introduces a novel technique for the detection of rutin in foods.

Developing a facile and effective assay method is crucial due to the potential harm of metronidazole (MNZ) antibiotics to both human health and the environment. Herein, snowflake-shaped poly (3-thiophenemalonic acid,...

Rapid and accurate detection of pathogenic bacteria is crucial for ensuring food safety and public health. In this study, we aimed to develop a novel molecularly imprinted polymer sensor based on screen-printed electrodes for the specific detection of Salmonella typhimurium. The sensor was constructed by electropolymerizing dopamine in the presence of Salmonella typhimurium on the electrode surface, followed by the removal of the bacteria to create specific binding cavities. The sensor demonstrated excellent specificity for Salmonella typhimurium, with a detection limit approximately of 101 CFU/ml and a detection time of only 4 min, with the sensor accurately differentiating Salmonella typhimurium from other common foodborne pathogens such as Escherichia coli and Listeria monocytogenes. The performance of the sensor was validated using real food samples, including pork and milk, showing its well suited for rapid and on-site detection of pathogenic bacteria. The development of this molecularly imprinted polymer with electrochemical sensor represents a significant advancement in the field of electrochemical biosensors, offering a promising tool for food safety monitoring and public health protection.

Accurate monitoring of hydroxyurea (HU) dosage is imperative in the administration of anticancer drugs. Existing determination methods face challenges such as operational complexity, low sensitivity, or high oxidation potentials. In this study, a novel HU electrochemical sensor (Zn/N-PC/GO/GCE) was synthesized using flower-shaped Zn/N co-doped porous carbon (Zn/N-PC) with graphene oxide (GO) through a one-step electrodeposition. The sensor features a distinctive three-step oxidation process for HU with a low oxidation potential, attributed to an electrochemical activation electrode strategy and crucial Zn/N co-doping in Zn/N-PC. Three electrons involved oxidation process of HU and Zn/N-PC/GO adsorption energy through transferred electrons and density functional theory (DFT). Under optimized conditions, the sensor demonstrated a broad linear detection range (1-1000 mu M) and an impressive limit of detection (LOD) of 0.52 mu M. Applicability was confirmed by analyzing HU in tablet formulations, urine and serum samples. This study presents an innovative electrochemical method for accurate HU monitoring, elucidating a potential three-step oxidation mechanism.

Fabrication of C-ZIF-67/SP/GCE for the simultaneous detection of DA and AC.

建立顶空固相微萃取-气相色谱-质谱联用技术测定60Co-γ射线辐照前后豫北白酒中香气成分类型(醇类、酯类、酸类和其他物质)及其含量的方法,并详细对比了辐照前后白酒样本中香气成分的具体变化.对影响顶空固相微萃取过程中的影响因素,即萃取头、预热时间、NaCl的质量浓度、样品装液量、萃取温度、萃取时间和解析时间都进行了优化,结果表明:萃取头为PDMS型,预热时间为20 min,NaCl质量浓度为0.1 g/mL,萃取温度为30℃,萃取时间为20 min,解析时间为15 min时效果最佳.在最合适的条件下分别对2019年和2015年原酒样及其辐照酒进行了定性和定量分析,结果显示不同的酒样所检测出的香气成分的数量及含量都不同.该研究初步探讨了辐照对豫北白酒香气成分的影响,为改善白酒品质提供了参考.

针对透平压缩机、透平膨胀机,推导了实际气体多变效率的计算方法,对重热现象的本质,以及重热系数的影响因素进行了详细分析.

针对阶梯型迷宫密封转子动力特性受进口预旋影响的问题,提出了考虑进口预旋的阶梯型迷宫密封动力特性计算方法.基于M urphy小位移涡动原理建立气流激振力-转子位移-转子速度的控制方程;采用计算流体力学(C FD)数值模拟方法对不同预旋比的全环密封流道进行计算,通过频域内求解控制方程得到了刚度和阻尼等动力特性参数,研究了不同预旋比的情况下阶梯型迷宫密封的动力特性;绘制了流道内的压力分布和流速矢量图,研究了阶梯型迷宫密封的流场特性.数值仿真结果表明:随着预旋比的增加,直接刚度在低频部分增大,在高频部分减小,交叉刚度几乎不变,交叉阻尼随预旋增加而减小;气流预旋明显降低了直接阻尼,相较于预旋比λ=0的情况,λ=0.255及λ=0.516的工况下直接阻尼的预估值平均减小了16.9％ 和21.4％;随着节流次数增加,气流经过密封齿的压降逐渐增加,分别为0.25、0.374和0.499 M Pa,密封齿顶的流速也逐渐增加,分别为79.5、88.36和106.0 m/s;由于密封齿阶梯式的排列增加了主流道的复杂性,阶梯密封流道分为节流区、射流区和涡流区,涡流区2个转向相反的旋涡增加了流道内气流动能的耗散.

用NUMECA软件对某空分离心式压缩机叶轮不同叶片数对机组性能的影响进行了研究.分析了叶片数对机组出口压力、等熵效率等的影响,对工程应用领域具有指导意义.

深入研究了汽轮机叶片标识技术及方法,研制出叶片各阶段标识的方法及使用设备,建立了基于SAP的标识管理系统,并实现叶片标识的全流程追溯,经过反复试验验证,效果显著,已经在全公司汽轮机叶片制造过程中得以全面推广和应用.

针对某旋转机械闭式叶轮,给出了叶轮推力的计算方法.汽封腔室中旋转因子的大小影响轮盘推力、轮盖侧推力,运用CFD数值计算,分析了汽封腔室中旋转因子的影响因素,得出漏气量大小对旋转因子的影响最显著,并且得出该旋转机械叶轮轮盖侧旋转因子取值0.55～0.60,轮盘侧取值0.40～0.46.

对某管线压缩机平衡盘进行防旋结构设计,经数值计算研究发现,防旋结构中与平衡盘直接接触的反吹气孔2的直径存在一个最佳范围可使防旋效果最优,考虑结构布置和气动效率,反吹气孔2轴向左偏更优,反吹气孔2的周向速度越小,在密封内的作用面积越大,密封间隙内的周向速度越均匀.

To circumvent the binder's adverse effect on the performance of electrochemical sensor and improve the analysis efficiency, a binder-free cobalt-doped Ni-MOF (Co/Ni-MOF) film, with honeycomb-like structure, is fast electrodeposited on glassy carbon electrode (GCE) by cathodic reduction. No conductive agent added, the Co/Ni-MOF/GCE can be directly used as a sensor for levofloxacin (LEV) determination. Under the optimal condition, a wider linear range of 0.1 uM-500 mu M LEV is obtained with the limit of detection (LOD, 3S/N) being 22 nM and the sensitivity of 2.85 mu A W-1 cm(-2). Further, when being used to analysis of LEV in e ye drop and spiked milk, satisfactory recoveries of 94.0%-108.2% are achieved. Particularly, benefiting of the synergistic effect of Co2+ and Ni2+, as well as and the binder-free film, the sensor exhibits an excellent sensitivity and a robust long-term stability. This work develops a facile and efficient strategy to synthesis of Co and Ni based MOF film, and provides them a new way in electrochemistry application. (C) 2020 Elsevier B.V. All rights reserved.

文章通过对比不同供热抽汽方案的特点,分析了各种方案对相关动叶安全性的影响.当供热抽汽量较小时,上游相邻级次动叶受供热参数的不同影响安全性可能下降.当抽汽量较大时,特别是部分负荷下,同时会导致低压末叶片进入小容积流量工况运行,将对末叶片的安全性造成不利影响.文中也说明了相关动叶安全性的校核方法和安全性解决措施.