Signal Conversion System Research Articles

Ratiometric fluorometric assay triggered by alkaline phosphatase: Proof-of-concept toward a split-type biosensing strategy for DNA detection

Herein, a sensitive ratiometric and split-type fluorescent sensing platform has been constructed for DNA detection based on one signal precursor and two fluorescent signal indicators. In this assay, o-phenylenediamine (OPD) was selected as the signal precursor. On one hand, Cu2+ can oxidize OPD to produce 2, 3-diaminophenazine (DAP), which with an emission peak at 555 nm. On the other hand, ascorbic acid (AA) could react with Cu2+ to generate dehydroascorbic acid (DHAA), which could further react with OPD to form 3-(1, 2-dihydroxy ethyl)furo[3, 4-b]quinoxalin-1 (3H)-on (DFQ) with a strong emission peak at 420 nm. As a result, the formation of DAP was inhibited, and leading to the decrease of fluorescence intensity at 555 nm. Alkaline phosphatase (ALP) could catalyze the substrate l-ascorbic acid-2-phosphate (AA2P) to produce AA in situ. Inspired by the successful use of ALP as a biocatalytic marker in bioassay, a split-type ratiometric fluorescent assay has been designed for DNA detection by using H1N1 DNA as the target model. It was realized for ratiometric fluorescent determination of H1N1 in a linear ranging from 50 pM to 1.5 nM with a limit of detection of 10 pM. The novel strategy could reduce the mutual interferences between the biomolecular recognition system and the fluorescence signal conversion system, which improving the accuracy of detection and effectively reducing the background signal. Furthermore, the strategy provided a promising platform for biomarkers detection in the fields of ratiometric fluorescent biosensors and bioanalysis.

Simulation study of an x-ray sub-picosecond resolution detection system based on time-domain amplification.

This study proposes what we believe to be a novel x-ray detection system that achieves a temporal resolution of 930fs with photorefractive and four-wave mixing effects. The system comprises two parts: a signal-conversion system and signal-acquisition system. The signal-conversion system is based on the photorefractive effect, which converts x-ray evolution into the variation of infrared interference intensity. The signal-conversion sensor consists of ultra-fast response LT-GaAs and a high-resolution interference cavity, achieving a resolution of 767fs. The signal-acquisition system consists of a time-domain amplification system based on four-wave mixing and a high-resolution signal-recording system with a resolution of 21ps, providing a temporal resolution of 525fs.

Magnetic relaxation switching biosensor via polydopamine nanoparticle mediated click chemistry for detection of chlorpyrifos

Traditional magnetic relaxation switching (MRS) biosensors suffer from poor sensitivity and unsatisfactory stability. In this study, a polydopamine (PDA) nanoparticles (NPs)-Cu2+ chelate complex mediated signal conversion system and a Cu+-catalyzed click chemistry triggered magnetic signal amplification system were evaluated and dynamically integrated into an MRS biosensor. Owing to abundant functional groups and a large surface area, PDA NPs enabled the absorption of a large amount of Cu2+ ions by chelation. The residual Cu2+ ions can be reduced with sodium ascorbate to Cu+, which could initiate the click reaction between azide-functionalized magnetic NPs (MNPs) and alkyne-functionalized MNPs that resulted in the production of aggregated nanoclusters. The transverse relaxation time (T2) depends on the degree of aggregation of MNPs; T2 is expressed as the magnetic signal readout. In addition, PDA NPs can be easily conjugated with antibodies by mixing, thus providing a straightforward bridge that integrates the immunoassay and magnetic signal readout. Combined with the high capacity of PDA NPs for chelating Cu2+ and high efficiency of click reaction for changing the T2 signals, the PDA-MRS biosensor enables the detection of chlorpyrifos with a limit of detection of 0.084 ng/mL, providing 22-fold enhancement than traditional enzyme-linked immunosorbent assay (1.86 ng/mL). This demonstrates its great potential for the detection of hazardous chemical molecules in a complex sample matrix.

Gold core @ platinum shell nanozyme-mediated magnetic relaxation switching DNA sensor for the detection of Listeria monocytogenes in chicken samples

Herein, an Au@Pt nanozyme-mediated magnetic relaxation switching (MRS) DNA biosensor has been developed for the rapid detection of Listeria monocytogenes. Au@Pt nanoparticle was with enhanced stability and high peroxidase activity for decomposing the hydrogen peroxide. After DNA hybridization and magnetic separation, the conjugates of MNP180-probe1-L. monocytogenes DNA-probe2-Au@Pt could adjust the hydrogen peroxide-mediated Mn(VII)/Mn(II) conversion, and thus leading to the change of the transverse relaxation time. The amount of Au@Pt was directly proportional to the concentration of L. monocytogenes. The Au@Pt nanozyme and the hydrogen peroxide-mediated Mn(VII)/Mn(II) signal conversion system contributed to the sensitivity and stability of this sensor. This sensor enabled the detection of L. monocytogenes with a LOD of 30 CFU/mL, which was 33-folds enhancement compared with that of enzyme-linked immunosorbent assay, providing a promising platform to trace the foodborne pathogen in the complex food matrix.

Online Glucose Analysis System With High Precision and Wide Detection Range for Fermentation Monitoring

Online glucose monitoring during the fermentation process is critical for evaluating the microbial metabolism state and reaction course, achieving precise process control for industrial efficiency enhancement. However, the fast, wide-range and highly accurate test technique always presents a challenge for state-of-the-art analytical instruments. In this work, we proposed an online glucose analysis system based on a homemade screen-printed enzymatic biosensor chip composed of Prussian blue nanocubes with a high sensitivity of 83.404 mA mM <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> . To match the detection behavior of this chip, a specific signal conversion system was designed to realize the highly precise acquisition and treatment of nA-level currents by integrating hardware acquisition circuits and Kalman filtering algorithms. Focusing on the continuous change in glucose concentration during fermentation, an adaptive injection strategy for the sampling volume was proposed to achieve an ultrawide linear range from 1 g/L to 180 g/L. The results show that the online analytical system exhibits excellent detection performance with high accuracy and low relative error of detection (<2%) during the fermentation of sophorolipid and ethanol compared to high performance liquid chromatography and commercial analyzers.

Copper Oxide Nanoparticle-Based Immunosensor for Zearalenone Analysis by Combining Automated Sample Pre-Processing and High-Throughput Terminal Detection.

A rapid and high-throughput fluorescence detection method for zearalenone (ZEN) based on a CuO nanoparticle (NP)-assisted signal amplification immunosensor was developed using an automated sample pretreatment and signal conversion system. CuO NPs with high stability and biocompatibility were used as carriers to immobilize anti-ZEN antibodies. The obtained CuO NP-anti-ZEN can maintain the ability to recognize target toxins and act as both a signal source and carrier to achieve signal conversion using automated equipment. In this process, target toxin detection is indirectly transformed to Cu2+ detection because of the large number of Cu2+ ions released from CuO NPs under acidic conditions. Finally, a simple and high-throughput fluorescence assay based on a fluorescent tripeptide molecule was employed to detect Cu2+, using a multifunctional microporous plate detector. A good linear relationship was observed between the fluorescence signal and the logarithm of ZEN concentration in the range of 16.0–1600.0 μg/kg. Additionally, excellent accuracy with a high recovery yield of 99.2–104.9% was obtained, which was concordant with the results obtained from LC-MS/MS of naturally contaminated samples. The CuO NP-based assay is a powerful and efficient screening tool for ZEN detection and can easily be modified to detect other mycotoxins.

A signal conversion system using binding-induced strand displacement for disease biomarker assay.

Using the principle of binding-induced DNA strand displacement (BINSD), a DNAzyme-powered nanomachine biosensor for multiple biomarkers via magnetic beads-based signal conversion was designed. This sensor can convert multiple biomarker recognition into release of predesigned output nucleic acids tagged with streptavidin proteins (SA-DNA) for activation of DNA nanomachines. In general, we adopted complementary base pairing rules and affinity ligand specific recognition, and three types of signal conversion systems were constructed that realized universal, sensitive, accurate, and specific detection of multiple biomarkers. Taking the advantage of the strong anti-interference capability of magnetic separation, this strategy could be used for detection of various biomarkers in clinical practice.

The determination of values of specific resistance to the cut of the radish top

The article deals with the problematic level of mechanization of small farms, especially during harvesting. When considering the process of harvesting root crops, including radish, the most difficult operation is the separation of tops. In this regard, the author conducted a series of studies to identify patterns of the process of cutting tops on the example of radish. The study was carried out using a dynamometric installation developed at the Azov-Black Sea Engineering Institute of Don State Agrarian University, the basis of which was a pendulum cutting device, to which elements a control and measuring system was connected, including a strain gauge; elements of the signal conversion system and a personal computer or laptop with the ADCLabSE software product. The factor experiment made it possible to establish that such parameters as the angle of blade installation, its thickness and cutting speed significantly affected the energy performance of the process of separating radish tops, and the influence of the first factor was the opposite, the rest were direct.&#x0D;

A Driver Circuit of Spatial Light Modulator

Spatial light modulator (SLM) driving circuit is an important constituent of photoelectric signal conversion system which has a very broad application prospects in various fields such as image display, image recognition, high-speed optical computing and optical communication system. In this study, a high speed and high precision driving circuit was developed, which was applied in 2 level grayscale image processing. This driving circuit adopted Charter .35µm technology. The testing results demonstrated that detection signal was able to follow the driving voltage of modulator and control the modulator on optical signal modulation.

Photoelectric Signal Conversion by Combination of Electron-Transfer Chain Catalytic Isomerization and Photoisomerization on Benzodimethyldihydropyrenes

Photochromic benzocyclophanediene showed oxidation-triggered isomerization to form benzodimethyldihydropyrene. The isomerization proceeded via an autocatalytic reaction system, which could be combined with the photochromic nature of the molecule to establish a new photoelectric signal conversion system.

A digital signal conversion system for astronomy radio interferometers with small antennas

Results of designing a digital signal conversion system for radio interferometers with small-diameter (up to 12 m) antennas are presented. The system contains four digital signal conversion channels with 500-MHz bandwidths. The output data stream rate in the VDIF format is 2048 Mbit/s per channel, and the cumulative output data flow is 8192 Mbit/s. The observation data flows arrive at the signal recording buffer unit and can be transmitted from there via a 10G Ethernet interface to a correlator in near-real time.

A radiointerferometric terminal of the Badary observatory

A radiointerferometric terminal recording signals on hard magnetic disks in the VSI-H format with a rate of up to 1024 Mbit/s is put into operation for the first time in Russia at the Badary observatory. This ensures the possibility of very-long-base radiointerferometry (VLBI) in quasi-real time. A P1000 signal conversion system containing 14 two-band video converters and a 16-channel 2-bit signal digitizing unit with a record-synchronizing device is designed for this terminal at the Institute of Applied Astronomy, Russian Academy of Sciences, and ZAO Radio-Electronic Processing Equipment. The signals are recorded by a Mark 5B recording equipment. The central computer of the radio telescope controls the terminal. Under the international and domestic programs, routine VLBI observations are conducted by the designed terminal in the Badary observatory.

Study on Sub-THz Signal Input for Superconducting Electronic Devices

Development of ultrafast optical interfaces that can operate in sub-terahertz region is important to apply superconducting electronic devices to the high-end systems. We have performed several fundamental researches to realize the ultrafast optical input interface for superconducting electronic devices. Firstly, we observed optical response of amorphous Ge thin films, and the results indicated that an amorphous Ge photoconductive switch could stably operate in a terahertz frequency range as an optical-to-electrical signal converter in the low-temperature region below T c of YBCO. Next, we have fabricated optical-to-electrical signal conversion system with photomixing technique, and we have demonstrated the generation and the detection of high frequency signals over 50 GHz. Finally, we have observed optical responses of a Josephson vortex flow transistor under irradiation of femtosecond laser pulses, and the results suggeste that the device has high potential as an optical interface.

센서를 이용한 전기장치 측정에 관한 연구

최근에 남북철도나 대륙횡단열차 등에 대한 사업성 타당조사가 이뤄지면서 철도차량에 대한 관심이 높아지고 있다. 타교통수단과 비교하여 철도차량은 환경친화적, 정시성, 신뢰성, 그리고 안전성의 특성이 있다. 우리는 한국형 고속철도차량을 평가하기 위한 하드웨어와 소프트웨어를 제작하였다. 소프트웨어는 측정된 데이터를 분석할 수 있도록 해준다. 이 논문에서는 센서를 사용한 철도차량 전기장치 측정에 관해서 연구하였다. 이 시험을 하기 위해서 신호변환시스템을 개발하였다. 이 계측시스템을 이용해서 가선전압, battery전압, 차축속도 등에 관한 중요한 시험결과를 얻을 수 있었다. Recently, as the road capacity reaches the limit and environmental problems becomes serious, there is gradually increased a need for railroad vehicles that are environment-friendly and have time regularity, reliability and safety. Accordingly, in addition to conventional railroad vehicles, lots of vehicles are being newly developed. We developed the hardware and software of the measurement system for on-line test and evaluation of korean high speed train. The software controls the hardware of the mesurement data and acts as interface between users and the system hardware. In this paper, we is studied for electric apparatus performance of railway vehicle using sensor. In order to this test is developed signal conversion system. Using this system, we obtained important result for pantograph voltage, battery voltage, axle speed, and inverter current.

A system for the coherent conversion of the signals of the centimeter-band astronomical very long baseline radio interferometer of the Scientific-Research Institute of Radiophysics

In the Scientific-Research Institute of Radiophysics we have developed specialized apparatus for the astronomical centimeter-band very long baseline radiointerferometer to solve a number of problems in astronomy, geodesy, and geodynamics [i]. The apparatus enables the main initial quantities (group delay and interference frequency) to be measured at the modern level of accuracy required. An important part of this apparatus is the system for the coherent conversion of the frequency of the received signals from the radio source. As is well known, this system can be constructed using an atc~nic frequency standard at each point of the very long baseline radio interferometer, the instability of which will determine the duration of the coherent storage of the interferometric signal. The problem reduces to transferring the highly stable properties of the signal of the frequency standard to the signals of the heterodynes, while ensuring their spectral purity. This is particularly important for an astronomical system for accurate and unambiguous measurements of interference frequency. In addition, the system for the coherent conversion of the signals of an astronomical very long baseline radio interferometer must carry out the conversion over a fairly broad frequency band, required to synthesize the corresponding broad effective frequency band, whose width to a large extent determines the final accuracy of the group-delav measurement [2]. i. Construction of the Centimeter-Band Coherent Signal Conversion System. The coherent signal conversion system we developed is a system with double freouency conversion with a receiving passband of 50 MHz, which converts the received centimeter-band signals into the operating band of the broadband frequency synthesis device (BFSD) of 30-76 MHz [3]. A block diagram of the system is shown in Fig. i. The signal of the first fixed-frequency heterodyne (FH) is generated directly from the 5-MHz signal from the Chi-69 rubidium frequency standard by multiplication, and the signal of the second heterodyne is obtained by multiplication of the output signal of a Ch6-58 frequency synthesizer, which is synchronized with the output signal of the same rubidium standard. The value of the second-heterodyne is set by the frequency synthesizer taking into account the previously calculated value of the differential Doppler frequency shift at the initial instant of each interferometer session of the observations of the space radio source. In existing very long base radio interferometer systems in the centimeter band, and some