基于有序介孔碳的氯离子选择性电极的制备及其在手持传感系统中的应用

以有序介孔碳(OMC)球为离子-电子转换层,制备了固态氯离子选择性电极,构建了基于离子敏感的场效应晶体管(ISFET)的手持式传感系统,用于检测人体血清中的氯离子。优化了OMC前驱体的碳化温度,探究了OMC形貌结构对电极传感性能的影响;电极柔性化制备后考察了其在手持系统中对氯离子的检测效果。结果表明,最优条件下,电极在5.12×10^-4~1.02 mol/L的浓度范围呈现线性响应,响应斜率为60 mV/decade。该柔性电极在手持传感系统中展现出高灵敏度和重现性,可用于人体血清样品中氯离子的检测,其回收率为96.3%~104.9%。     

Nano-sized local magnetic field induced by circular motion of ions and molecules in a nanotorus under gigahertz rotating electric fields

Recently, we reported molecular dynamics simulations of stable cyclotron motions of ions and water molecules in a carbon nanotorus, induced by different rotating electric fields (EFs). This study is devoted to the calculation and characterisation of the magnetic field (MF) induced by these cyclotron motions. Results show that carbon nanotorus containing ions or water molecules acts as an EF-to-MF transducer. Components of the instantaneous induced MF show large-scale oscillations superimposed by strong fluctuations arising respectively from overall circular motion and random collisions of moving species. Analysis of the space-dependencies of the induced MF components shows that the induced MF is maximum at the centre of the nanotorus. The MF induced by cyclotron motion of ions follows the orders B(Ca²⁺)?>?B(Na⁺)?≈?B(K⁺) at E?=?1.0?V/nm and B(E?=?1.0?V/nm)?>?B(E?=?0.5?V/nm)?>?B(E?=?0.1?V/nm). The time-averaged induced MF of the cyclotron motion of 81 water molecules is almost 10² times stronger than that of ions. The induced MF strength is decreased with increasing distance from nanotorus and decays effectively at about 17.3–18.1 and 15.9–18.2?nm along the z-axis of the nanotorus for ions and water molecules, respectively. The magnitude of the MF induced by cyclotron motions of water molecules and ions, respectively, decreases and increases in the nanotorus with freed carbon atoms.     

Interactions of DNA with graphene and sensing applications of graphene field-effect transistor devices: A review

Graphene field-effect transistors (GFET) have emerged as powerful detection platforms enabled by the advent of chemical vapor deposition (CVD) production of the unique atomically thin 2D material on a large scale. DNA aptamers, short target-specific oligonucleotides, are excellent sensor moieties for GFETs due to their strong affinity to graphene, relatively short chain-length, selectivity, and a high degree of analyte variability. However, the interaction between DNA and graphene is not fully understood, leading to questions about the structure of surface-bound DNA, including the morphology of DNA nanostructures and the nature of the electronic response seen from analyte binding. This review critically evaluates recent insights into the nature of the DNA graphene interaction and its affect on sensor viability for DNA, small molecules, and proteins with respect to previously established sensing methods. We first discuss the sorption of DNA to graphene to introduce the interactions and forces acting in DNA based GFET devices and how these forces can potentially affect the performance of increasingly popular DNA aptamers and even future DNA nanostructures as sensor substrates. Next, we discuss the novel use of GFETs to detect DNA and the underlying electronic phenomena that are typically used as benchmarks for characterizing the analyte response of these devices. Finally, we address the use of DNA aptamers to increase the selectivity of GFET sensors for small molecules and proteins and compare them with other, state of the art, detection methods.     

Coupling of Biomolecular Logic Gates with Electronic Transducers: From Single Enzyme Logic Gates to Sense/Act/Treat Chips

The integration of biomolecular logic principles with electronic transducers allows designing novel digital biosensors with direct electrical output, logically triggered drug‐release, and closed‐loop sense/act/treat systems. This opens new opportunities for advanced personalized medicine in the context of theranostics. In the present work, we will discuss selected examples of recent developments in the field of interfacing enzyme logic gates with electrodes and semiconductor field‐effect devices. Special attention is given to an enzyme OR/Reset logic gate based on a capacitive field‐effect electrolyte‐insulator‐semiconductor sensor modified with a multi‐enzyme membrane. Further examples are a digital adrenaline biosensor based on an AND logic gate with binary YES/NO output and an integrated closed‐loop sense/act/treat system comprising an amperometric glucose sensor, a hydrogel actuator, and an insulin (drug) sensor.     

非线性工作状态压电换能器匹配技术

针对压电换能器在大功率下存在复杂非线性而导致匹配参数难以优化的问题,以大功率超声金属焊接为例,通过采集测试焊接过程换能器两端电压的幅值与频率,建立换能器反谐振电阻与驱动电压有效值、频率之间的数学模型;提出基于反谐振电阻模型的最优功率匹配方法,推导了匹配电感电容的计算公式。最后实验验证了数学模型的准确性,且当换能器输入功率在最优功率附近时,匹配网络电能传输效率最高。     

Measurement of concrete internal strain using a three-dimensional transducer system

A new three-dimensional transducer system is introduced in this paper, which enables the measurement of six internal components of strain tensor in concrete members. Laboratory tests and strain analyses were carried out to evaluate this tranducer system. The results show that the system is effective in measuring internal strains of concrete members. It was then embedded in a reinforced concrete bridge deck in Macomb County, Michigan. Field tests were conducted to measure the strains in the deck under truck wheel load. The results were used to understand the deck's strain and stress behavior under truck wheel load.     

Properties of cat-eye modulating retro-reflector and its application with piezoelectric transducer

Piezoelectric cat-eye modulating retro-reflector (MRR) is the core component of an acousto-optic retro-identification system. The influence of the optical parameters (link distance l, lens focal length f and the detector diameter r) to the cat-eye effect was analyzed theoretically and experimentally. A piezoelectric cat-eye retro-identification (PCERI) system was built, and an information transmission ratio of 2 kHz was achieved which can satisfy an access control system.     

Effects of multi-frequency ultrasound on freezing rates and quality attributes of potatoes

The effects of multi-frequency ultrasound assisted freezing on the freezing rate, microstructure, quality properties (drip loss, firmness, total calcium content, l-ascorbic acid content and total phenol content) of potatoes were studied. The results indicated that the freezing effects of multi-frequency ultrasound was better than those of single-frequency ultrasound. Multi-frequency ultrasound could significantly increase the freezing rate and preserve the quality of frozen samples better. With increase in the number of ultrasonic frequencies, the freezing effect was more obvious. In addition, scan electron microscopy (SEM) images showed that the ice crystals formed by the multi-frequency ultrasonic treatment were fine and uniformly distributed, which caused less damage to the frozen potato samples. From the analysis of the quality attributes, the nutritional values of the samples after multi-frequency ultrasonic treatment was higher, but attention should be paid to the negative influence of the hydroxyl radical generated by the multi-frequency ultrasound.     

Effect of multi-frequency power ultrasound (MFPU) treatment on enzyme hydrolysis of casein

Effect of multi-frequency power ultrasound (MFPU) pretreatments on the degree of hydrolysis (DH) and mechanism of casein during alcalase enzymolysis was investigated. Results showed that MFPU pretreatment in tri-frequency 20/40/60 kHz mode significantly (p < 0.05) improved the DH value of casein. Variation of intrinsic fluorescence spectrum indicated the unfolding and degradation of casein occurred after MFPU pretreatment. Fourier transform infrared spectra showed that α-helix and β-sheet content of MFPU pretreated casein decreased, while β-turn and random coil content increased. Surface topography and nanostructures of caseins were found modified after MFPU pretreatments by the analysis of scanning electron microscopy (SEM) and atomic force microscopy (AFM). The SEM analysis also indicated that the enzymolysis residues of casein pretreated by MFPU were smaller than untreated samples. In conclusion, the MFPU can be used as an efficient pretreatment method to promote the enzymolysis of casein.     

宽体液腔Janus-Helmholtz换能器

本文使用有限元方法对宽体液腔Janus-Helmholtz(JH)换能器进行了仿真分析,得出了壳体宽度拓展增量对JH换能器工作性能的影响规律。使用三维建模的方式,分析了连接部分对换能器性能的影响及宽体壳体的的模态,证明了三维建模的必要性。依据仿真优化结构设计了一款宽体液腔JH换能器并进行了湖上测试。最终测试结果与仿真结果有很好的一致性,相较直筒JH换能器其谐振频率降低300Hz,发射电压响应最高可达144dB。