High-sensitivity Measurement System Research Articles

ESTABLISHMENT OF A NEW SPECIFIC HIGH SENSITIVITY MEASUREMENT SYSTEM FOR SOLUBLE ANGIOTENSIN IV RECEPTOR

Objective: The renin angiotensin system plays a pivotal role in the development of cardiovascular and renal conditions. We had identified angiotensin IV receptor (AT4) as a hypertension/diabetes-specific gene through systemic transcriptome analysis followed by ontology based hierarchical clustering. Previously we have established a measurement system for soluble AT4 (sAT4) by polyclonal antibodies with 1 μg/ml sensitivity. Actual measurements for clinical subjects suggest the sAT4 measurement system would be useful for assessment of the pathophysiology of hypertension/obesity. Thus, we tried to establish a new specific high sensitivity measurement system for sAT4 with monoclonal antibodies. Design and method: As the antigen, we prepared a recombinant protein of AT4. Mice were immunized with the protein then spleen and lymph nodes were applied to make hybridomas with X63. We have screened the clones and selected candidate clones. Then we tested the best combination of the antibodies for the sandwich ELISA system and then optimized the reaction conditions. With this system, as a pilot study, we measured plasma concentrations of 114 subjects with life style related diseases and investigated relationships of sAT4 with various clinical and biochemical parameters by ANOVA. Results: Based on the standard curve for serial-step dilutions against reference molecules, the new measurement system for sAT4 showed 20 pg/ml sensitivity, 3–8 % intra-assay CV and about 10 % inter-assay CV without cross reactivities against 3 standard substrates. Actual measurements on clinical subjects revealed that the sAT4 values tended to be lower on hypertensive cases, obesity cases and dyslipidemic cases and that the sAT4 values were significantly low on CKD cases. Conclusions: Thus, we could establish a new specific high sensitivity measurement system for sAT4. The AT4 was originally identified from GLUT4 vesicles and thought to be involved in insulin sensitivity. It is also known to degrade angiotensin III to IV. Besides these findings, our data suggest the possibility that AT4 is involved in the pathophysiology of hypertension/obesity in a high sensitivity level for the first time. As perspectives we will assess the distribution of the concentrations and will measure the adequate numbers based on statistical power.

Discharge Characteristics and Detectability of Metal Particles on the Spacer Surface in Gas-Insulated Switchgears

Metal particles and dirty contaminants on the spacer surface are mainly considered to be the critical factor in sudden flashovers. Understanding the discharge characteristics as well as the detectability of metal particles in the gas-insulated switchgear (GIS) will be helpful in improving its safety and reliability. In this paper, a high-sensitivity measurement system based on cross-reference pulse current (PC) and ultra-high-frequency (UHF) methods was established. The PC and UHF signals generated by partial discharges (PDs) of metal particles of different lengths (<i>&#x03A6;</i> &#x003D; 0.5 mm, <i>L</i> &#x003D; 2, 5, 8, and 10 mm) at different positions on a real spacer surface were studied. The PD characteristics and detectability of the metal particles on the spacer surface were obtained while the detection limitation was also discussed. It is found that under PD test condition, the apparent charge of the PDs is less than 1 pC for particles shorter than 5 mm, and the conventional PD detection method have limitations in detecting these short particles on the spacer surface. Under operation condition, only the apparent charge of particles longer than 8 mm can exceed 1 pC, which means it is difficult to detect the particles shorter than 8 mm in field. However, the result indicates that even the 5 mm long particle will be harmful to the GIS. Meanwhile, it is also been found that the detection sensitivity also has a great influence on the judgement of PD severity. This study is of great interest for understanding the PD characteristics, discharge levels, and detectability of short metal particles on spacer surface.

Design and Sensitivity Improvement of CMOS-MEMS Scanning Microwave Microscopes

In this paper, we present the performance and imaging results of an integrated single-chip CMOS-microelectromechanical systems (MEMS) scanning microwave microscope (SMM). A systematic analysis for sensitivity improvement is described in detail. We first explain why it is important to have high sensitivity for this type of microscope and then propose a systematic method to analyze and design the entire structure for better sensitivity. For this, accurate lumped models are derived for each section of the system and comparisons are made between different designs. Furthermore, a new concept based on the quality factor of the individual sections is described to give the designer a tool to improve the sensitivity of individual sections without the need to simulate or model the entire system. A high-sensitivity measurement system is also explained. Finally some measurement results are presented. While the analysis presented in this paper is for CMOS-MEMS SMM, it is applicable to any type of SMM.

High sensitive translational temperature measurement using characteristic curve of second harmonic signal in wavelength modulation spectroscopy

A high sensitive measurement system of translational temperature of plasma was developed. In this system, which is based on wavelength modulation spectroscopy, a peak value of second harmonic signal was measured as a function of modulation depth. The translational temperature was estimated by fitting the theoretically calculated curve to the measured characteristic curve. The performance of this system was examined using microwave discharge plasma. As a result of comparison with conventional laser absorption spectroscopy, both results show good agreement in the measurable region of the laser absorption spectroscopy. Next, the measurable limit of this system was investigated by decreasing the target number density. The detectable fractional absorption was as low as 3.7 × 10-5 in which condition the signal to noise ratio was the order of single digit at the averaging number of 40. This value is more than two orders of magnitude lower than that of the laser absorption spectroscopy.

Publisher's Note: "High sensitivity measurement system for the direct-current, capacitance-voltage, and gate-drain low frequency noise characterization of field effect transistors" [Rev. Sci. Instrum. 87, 044702 (2016)

Publisher's Note: "High sensitivity measurement system for the direct-current, capacitance-voltage, and gate-drain low frequency noise characterization of field effect transistors" [Rev. Sci. Instrum. 87, 044702 (2016)

High sensitivity measurement system for the direct-current, capacitance-voltage, and gate-drain low frequency noise characterization of field effect transistors.

Measurements of current fluctuations originating in electron devices have been largely used to understand the electrical properties of materials and ultimate device performances. In this work, we propose a high-sensitivity measurement setup topology suitable for the automatic and programmable Direct-Current (DC), Capacitance-Voltage (CV), and gate-drain low frequency noise characterization of field effect transistors at wafer level. Automatic and programmable operation is particularly useful when the device characteristics relax or degrade with time due to optical, bias, or temperature stress. The noise sensitivity of the proposed topology is in the order of fA/Hz(1/2), while DC performances are limited only by the source and measurement units used to bias the device under test. DC, CV, and NOISE measurements, down to 1 pA of DC gate and drain bias currents, in organic thin film transistors are reported to demonstrate system operation and performances.

Direct measurement of catalase activity in living cells and tissue biopsies

Spatiotemporal regulation of enzyme-substrate interactions governs the decision-making steps in biological systems. Enzymes, being functional units of every living cell, contribute to the macromolecular stability of cell survival, proliferation and hence are vital windows to unraveling the biological complexity. Experimental measurements capturing this dynamics of enzyme-substrate interactions in real time add value to this understanding. Furthermore these measurements, upon validation in realistic biological specimens such as clinical biopsies – can further improve our capability in disease diagnostics and treatment monitoring. Towards this direction, we describe here a novel, high-sensitive measurement system for measuring diffusion-limited enzyme-substrate kinetics in real time. Using catalase (enzyme) and hydrogen peroxide (substrate) as the example pair, we demonstrate that this system is capable of direct measurement of catalase activity in vitro and the measured kinetics follows the classical Michaelis-Menten reaction kinetics. We further demonstrate the system performance by measuring catalase activity in living cells and in very small amounts of liver biopsies (down to 1 μg total protein). Catalase-specific enzyme activity is demonstrated by genetic and pharmacological tools. Finally we show the clinically-relevant diagnostic capability of our system by comparing the catalase activities in liver biopsies from young and old mouse (liver and serum) samples. We discuss the potential applicability of this system in clinical diagnostics as well as in intraoperative surgical settings.

1210 半導体レーザによる酸素分子の高速高感度吸収分光システムの開発IV(GS-6,19 熱計測・宇宙工学)

1210 半導体レーザによる酸素分子の高速高感度吸収分光システムの開発IV(GS-6,19 熱計測・宇宙工学)

713 半導体レーザによる酸素分子の高速高感度吸収分光システムの開発 III(GS-5・6 流体計測(2))

713 半導体レーザによる酸素分子の高速高感度吸収分光システムの開発 III(GS-5・6 流体計測(2))

G060062 半導体レーザによる酸素分子の高速高感度吸収分光システムの開発II([G06006]熱工学部門一般セッション(6)二燃焼の分光計測および輻射)

G060062 半導体レーザによる酸素分子の高速高感度吸収分光システムの開発II([G06006]熱工学部門一般セッション(6)二燃焼の分光計測および輻射)

Pulsed excitation source multiplexed fluorometry for the simultaneous measurement of multiple analytes. Continuous measurement of atmospheric hydrogen peroxide and methyl hydroperoxide.

Presently, solid-state sources such as light-emitting diodes (LEDs) provide for intense, nearly monochromatic light. They are available over a broad range of emission wavelengths. Unlike incandescent and discharge lamps, LEDs can be turned on and off at high speeds. The resulting light pulses are highly reproducible. This allows the use of a single photomultiplier tube (PMT), often the most expensive component in a high-sensitivity measurement system, as a multiplexed detector with multiple, fiber-optic-coupled, fluorescence-detection cells excited by solid-state sources. A time resolution of 1 min is adequate in many continuous detection schemes. This enables multiple-channel single-detector multiplexed measurement without any loss of S/N. On the basis of this principle, we describe a new automated continuous instrument for the simultaneous measurement of atmospheric hydrogen peroxide and methyl hydroperoxide (MHP). A Nafion membrane diffusion scrubber (DS) is used with hematin-catalyzed oxidation of thiamine to thiochrome for the measurement of H2O2, and an expanded poly(tetrafluoroethylene) (ePTFE) DS is used with a H2O2 destruction catalyst and horseradish peroxidase-catalyzed oxidation of thiamine to thiochrome for the measurement of MHP. The respective limits of detection are 25 pptv and 15 pptv. Design, performance details, and illustrative results from a field campaign (Philadelphia NEO3PS study, 2001) are presented.

Electro-optic sampling of surface space-charge fields on III–V compounds

Time-resolved reflective electro-optic sampling (REOS) of ultrafast longitudinal surface fields on III–V compounds is accomplished with 50 fs optical pulses at 2 eV. Ultrafast carrier transport and screening effects of the photoexcited carriers initiate electric field transients short enough to impulsively launch longitudinal-optical phonons, in phase. A high-sensitivity measurement system allows the time-resolved investigation of the coherent phonon modes and carrier transport. In a special example the mapping of process-induced changes in the surface space charge region is demonstrated.

光位相変調器とファラデー素子を用いた高感度自動複屈折測定装置の開発

In the fundamental research of optical materials, it has been necessary to measure their polarized functions. Especially, a little birefringence in the ultra thin film such as Langmuir-Brodgett film and its dynamic characteristics such as liquid crystal have not had clearly data and many discussions. Therefore, we are developing a high sensitive measurement system of dynamic birefringence using optical phase modulator (Pockels device) and two Faraday rotators (Faraday device). This report describes some basic workings of the new high sensitive measurement system. It was possible to measure a small birefringence (retardation 5×10-3 rad) and fast axis angle of sample.