Real-time Measurement Technique Research Articles

Effect of Resveratrol and Derivatives on Interactions between Alzheimer's Disease Associated Aβ Protein Oligomers and Lipid Membranes: A Quartz Crystal Microbalance Analysis

Resveratrol and derivatives, abundant natural polyphenols in red wine, have been speculated to be responsible for the association between moderate red wine consumption and a reduced incidence of Alzheimer's disease (AD). Amyloid-β (Aβ) protein is highly involved in the pathology of AD, and one proposed mechanism for its pathogenesis is that Aβ aggregates’ interactions with lipid membranes induces cytotoxicity. This study investigates the effect of resveratrol and its derivatives on interactions between Aβ oligomers and lipid membranes modeled by supported lipid bilayers (SPBs).SPBs comprised of POPC, DPPC and DPPG are formed on the surface of a SiO2-coated quartz crystal for monitoring using a quartz crystal microbalance (QCM). QCM is a highly sensitive, real-time mass measurement technique based on the piezoelectric property of quartz. QCM can continually measure a crystal's resonance frequency shifts, which linearly correlate with changes in deposited mass. This study, by measuring the mass deposition rate, evaluates the binding between Aβ oligomeric aggregates and lipid membranes consisting of varying POPC/DPPC/DPPG ratios. The effect of resveratrol and its derivatives on Aβ-lipid interactions is additionally assessed by preparing Aβ oligomers in the presence of different polyphenols and comparing their respective deposition rate upon SPBs.The binding of Aβ aggregates to lipid membrane is believed to cause defects within the membrane and result in functional disorders. Thus, polyphenols that can effectively reduce this binding have the potential to protect membranes from disturbance and might be therapeutic for AD.

A novel accelerometer based feedback concept for improving machine dynamic performance

Abstract: Small size ultra-precision Computer Numerical Control (CNC) machines require high dynamic performance. Flexible frame phenomena can limit the machine dynamic performance, particularly in small size machines. A novel accelerometer based feedback concept for improving machine dynamic performance was developed and realised, a virtual metrology frame. It expends the limited techniques for improving dynamic performance of a small size machine by measuring the flexible frame displacement, and feeding it into the controller. The concept was implemented in a simplified linear motion system, and showed a 12dB reduction in the magnitude of the first resonance in the plant frequency response function. This allowed improving the servo bandwidth by 58% based on a PID controller. A new technique for real-time dynamic displacement measurements using accelerometer was developed. It shows a low sensor noise σ

Sensing performance of dielectric sensor in mixed melting polymer pellets for waste plastic separation

Physical value of dielectric properties among relative permittivity, dielectric loss and loss tangent of mixed melting polymer pellets were measured under temperature variance condition and measurement frequency from 0.5MHz to 5MHz in order to develop a real-time non-intrusive measurement technique for high performance waste plastic separation. Various volume fractions of non-polar polyethylene (PE) and polar polyethylene terephthalate (PET) were used as the mixed polymer pellets. As the results, with the volume fractions of PET from 0.05 to 0.22, as the temperature is increased up to melting point temperature and above mold temperature, the relative permittivity is decreased as the temperature is increased. However over melting temperature up to the mold temperature, the relative permittivity is slightly increased as the temperature is increased. On the other hand, the dielectric loss and loss tangent are not affected by the temperature variance, and the dielectric loss and loss tangent are increased as the measurement frequency is increased. As the conclusions, at molding temperature 180°C (453K), the highest sensitivity of dielectric property is the relative permittivity. Meanwhile, the highest linearity relationship between PET volume fraction and predicted relative permittivity is achieved at the measurement frequency of 5MHz. From relative permittivity measurement in these conditions, the performance to distinguish PET volume fraction 0.05 from PE volume fraction 0.95 is achieved in the mixed melting polymer pellets. Therefore, the relative permittivity measurement for waste plastic separation has a possibility to achieve the high purity recycled plastics as compared with conventional methods.

Protein Conformational Changes Are Detected and Resolved Site Specifically by Second-Harmonic Generation

We present here a straightforward, broadly applicable technique for real-time detection and measurement of protein conformational changes in solution. This method is based on tethering proteins labeled with a second-harmonic generation (SHG) active dye to supported lipid bilayers. We demonstrate our method by measuring the conformational changes that occur upon ligand binding with three well-characterized proteins labeled at lysine residues: calmodulin (CaM), maltose-binding protein (MBP), and dihydrofolate reductase (DHFR). We also create a single-site cysteine mutant of DHFR engineered within the Met20 catalytic loop region and study the protein’s structural motion at this site. Using published x-ray crystal structures, we show that the changes in the SHG signals upon ligand binding are the result of structural motions that occur at the labeled sites between the apo and ligand-bound forms of the proteins, which are easily distinguished from each other. In addition, we demonstrate that different magnitudes of the SHG signal changes are due to different and specific ligand-induced conformational changes. Taken together, these data illustrate the potential of the SHG approach for detecting and measuring protein conformational changes for a wide range of biological applications.

Graphics processing unit-assisted real-time three-dimensional measurement using speckle-embedded fringe.

This paper presents a novel two-frame fringe projection technique for real-time, accurate, and unambiguous three-dimensional (3D) measurement. One of the frames is a digital speckle pattern, and the other one is a composite image which is generated by fusing that speckle image with sinusoidal fringes. The contained sinusoidal component is used to obtain a wrapped phase map by Fourier transform profilometry, and the speckle image helps determine the fringe order for phase unwrapping. Compared with traditional methods, the proposed pattern scheme enables measurements of discontinuous surfaces with only two frames, greatly reducing the number of required patterns and thus reducing the sensitivity to movements. This merit makes the method very suitable for inspecting dynamic scenes. Moreover, it shows close performance in measurement accuracy compared with the phase-shifting method from our experiments. To process data in real time, a Compute Unified Device Architecture-enabled graphics processing unit is adopted to accelerate some time-consuming computations. With our system, measurements can be performed at 21 frames per second with a resolution of 307,000 points per frame.

Study of laser-induced chlorophyll fluorescence lifetime measurement and its correction

A novel method for laser-induced fluorescence lifetime measurement and correction are presented to improve precision of chlorophyll fluorescence lifetime measurement. Laser was used as excitation source for exciting chlorophyll fluorescence. According to the measured signals characteristics, the fluorescence and background signals were detected respectively by photomultiplier. The chlorophyll fluorescence lifetime can be estimated from deconvolution of the fluorescence and background signals. Based on a number of retrieved results from simulations, a rule of inherent error with deconvolution was found. Therefore, the calibration formula was obtained through the comparison of ideal fluorescence lifetimes and retrieved ones. In actual measurements, the intrinsic fluorescence decay can be separated from the measured signals by deconvolution, and thus, the retrieved fluorescence lifetimes were substituted into a calibration formula to calculate the corrected values. Both simulations and experiments show that the method is a high precision and real-time measurement technique for chlorophyll fluorescence lifetime.

Application of laser-induced breakdown spectroscopy in carbon sequestration research and development

The success of carbon capture and storage (CCS) programme relies on the long-term isolation of CO2 from the atmosphere. Therefore, technologies concomitant to physical storage of CO2 such as reliable measurement, monitoring, and verification (MMV) techniques are needed to ensure that the integrity of the storage site is maintained. We propose the use of laser-induced breakdown spectroscopy (LIBS) analytical technique to detect carbon dioxide leaks to aid in the successful application of CCS. LIBS has a real-time monitoring capability and can be reliably used for the elemental and isotopic analysis of solid, liquid, and gas samples. The flexibility of probe design and use of fibre optics make it a suitable technique for real time measurements in harsh conditions and at hard-to-reach places. Proposed monitoring with LIBS includes terrestrial soil samples, water samples from monitoring wells or from different formations, air samples from monitoring wells or suspected leakage areas. This work details the laboratory scale experiments to measure carbon contents in rock, soil, aqueous, and air samples. The potential of the technology for measurements in high pressure high-temperature conditions will also be discussed.

Real-time measurements of endogenous carbon monoxide production in isolated pig lungs

Ischemia-reperfusion injuries are a critical determinant of lung transplantation success. The endogenous production of carbon monoxide (CO) is triggered by ischemia-reperfusion injuries. Our aim was, therefore, to assess the feasibility of exhaled CO measurements during the ex vivo evaluation of lungs submitted to ischemia-reperfusion injuries. Five pigs were euthanized and their lungs removed after pneumoplegia. After cold storage (30 min, 4°C), the lungs were connected to an extracorporeal membrane oxygenation circuit, slowly warmed-up, and ventilated. At the end of a 45-min steady state, CO measurements were performed by optical-feedback cavity-enhanced absorption spectroscopy, a specific laser-based technique for noninvasive and real-time low gas concentration measurements. Exhaled CO concentration from isolated lungs reached 0.45±0.19 ppmv and was above CO concentration in ambient air and in medical gas. CO variations peaked during the expiratory phase. Changes in CO concentration in ambient air did not alter CO concentrations in isolated lungs. Exhaled CO level was also found to be uncorrelated to heme oxygenase (HO-1) gene expression. These results confirm the feasibility of accurate and real-time CO measurement in isolated lungs. The presented technology could help establishing the exhaled CO concentration as a biomarker of ischemia-reperfusion injury in ex vivo lung perfusion.

A new technique for the characterization of the water leaching behavior of space holding particles in the preparation of biomedical titanium scaffolds

In this study, a new real-time measurement technique for the characterization of the water leaching behavior of space holding particles from titanium scaffold preform for bone tissue engineering was developed. This technique yielded accurate and reproducible data. Fitting the data acquired into the existing solvent debinding models led to plots that could be used to elucidate the mechanisms operating during the space holder removal process through water leaching, i.e., (i) rapid dissolution, (ii) dissolution and diffusion and (iii) saturation.

多束高重复频率全光纤激光脉冲时间波形实时精密测量技术

多束高重复频率全光纤激光脉冲时间波形实时精密测量技术

Study of granule growth kinetics during in situ fluid bed melt granulation using in-line FBRM and SFT probes

Objective: The aim of this work was to study the granule growth kinetics during in situ fluid bed melt granulation process using real-time particle size measurement techniques. In addition, the usefulness of these techniques during scale-up of melt granulation was evaluated.Materials and methods: Focused beam reflectance measurement (FBRM) and spatial filtering technique (SFT) probes were used within the process chamber of fluid bed granulator for real-time in-line granule size analysis.Results: The results demonstrated that the use of in-line particle size probes in fluid bed granulator during the process offers an insightful view of granule growth and allows in-process monitoring of granule chord length changes. The effect of selected critical parameters (binder content, inlet air temperature and product endpoint temperature) on the granule growth was clearly presented by in-line measurements in a laboratory scale. A comparison of granule size measurements from both FBRM and SFT probes showed similar particle growth trends, which were in close correlation to the product temperature. Comparable trends in end granule particle size were observed when comparing different in-line, at-line and off-line particle size measurements.Conclusion: The in-line FBRM and SFT probes were successfully employed in in situ fluid bed melt granulation process to study the influence of critical formulation/process parameters on the granule growth kinetics. The scale-up experiment confirmed the potential of these in-line granule size measurement techniques as a viable tool for process monitoring during the transfer of granulation to the larger scale or another manufacturing site/equipment.

A calibration-based approach to real-timein vivomonitoring of pyruvate C1and C2polarization using theJCCspectral asymmetry

A calibration-based technique for real-time measurement of pyruvate polarization by partial integral analysis of the doublet from the neighbouring J-coupled carbon is presented. In vitro calibration data relating the C2 and C1 asymmetries to the instantaneous C1 and C2 polarizations, respectively, were acquired in blood. The feasibility of using the in vitro calibration data to determine the instantaneous in vivo C1 and C2 polarizations was demonstrated in the analysis of rat kidney and pig heart spectral data. An approach for incorporating this technique into in vivo protocols is proposed.

Effect of loading rate on fracture toughness and failure micromechanisms in marble

Fracture experiments in a notched semi-circular bend configuration were conducted to characterize rate effects and failure micromechanisms of a marble using a servo-hydraulic machine and a modified split Hopkinson pressure bar. Three real-time measurement techniques were used to estimate crack propagation velocities and full-field deformation fields. Micro-measurement techniques were employed to qualitatively and quantitatively identify micrograph and surface morphology. Based on the theory of fracture mechanics, a micromechanical model was presented to examine the intergranular and transgranular fracture. The results indicated that fracture toughness and surface roughness were dependent on loading rate, which were induced by the intrinsic failure mechanisms.

High-speed three-dimensional profilometry for multiple objects with complex shapes

This paper describes an easy-to-implement three-dimensional (3-D) real-time shape measurement technique using our newly developed high-speed 3-D vision system. It employs only four projection fringes to realize full-field phase unwrapping in the presence of discontinuous or isolated objects. With our self-designed pattern generation hardware and a modified low-cost DLP projector, the four designed patterns can be generated and projected at a switching speed of 360 Hz. Using a properly synchronized high-speed camera, the high-speed fringe patterns distorted by measured objects can be acquired and processed in real-time. The resulting system can capture and display high-quality textured 3-D data at a speed of 120 frames per second, with the resolution of 640 × 480 points. The speed can be trebled if a camera with a higher frame rate is employed. We detail our shape measurement technique, including the four-pattern decoding algorithm as well as the hardware design. Some evaluation experiments have been carried out to demonstrate the validity and practicability of the proposed technique.

In situ, real-time thickness measurement techniques for bath-deposited CdS thin films on Cu(In,Ga)Se2

A technique has been developed that can measure the thickness of a 30–70nm thin film of cadmium sulfide on a Cu(In,Ga)Se2 substrate, in real time, as it grows in a chemical bath. The technique does not damage the film, and can be used to monitor batch depositions and roll-to-roll depositions with equal accuracy. The technique is based on reflectance spectroscopy through the chemical bath.

Loaded dice

Using a real-time measurement technique to study the single-shot properties of modulation instability, scientists have shown that its initial stochastic nature in an optical system can lead to specific correlation properties in both the spectral and temporal domains.

Depth dose determination for a mixed radiation field using a thin plastic scintillator dosimetry system

Plastic scintillators, due to their favorable characteristics compared with other dosimetry techniques, were used as detectors to estimate dose distributions in high gradient dose fields. In this study, a thin plastic scintillator (type BC-408) was coupled to a photomultiplier tube and multichannel analyzer as a technique for real-time dose measurements. The well-defined beta, gamma, and beta-gamma emitters (137Cs, 133Ba, 22Na, 109Cd, 55Fe, and 241Am) have enabled parallel depth dose measurements with Monte-Carlo calculations to be critically compared. The measurements of doses were made for depths range of 0.1 mm to 5 mm. The MCNP dose results were comparable with the plastic scintillator detector and can be used to approximately estimate the dose rate values from mixed electron-photon fields. The minimum dose rate that can be measured by the plastic scintillator system was ~2 ?Gy/h and was for 109Cd source of activity 222 Bq.

Intravascular Microdialysis as a Method for Measuring Glucose and Lactate during and after Cardiac Surgery

The aim was to evaluate intravascular microdialysis as a method for measuring blood glucose and lactate in a clinical setting during and after cardiac surgery. Ten patients undergoing cardiac surgery were included. A microdialysis catheter was percutaneously placed in the superior vena cava or right atrium. Glucose and lactate values measured by the microdialysis technique were analyzed and compared with reference methods, i.e., arterial and venous blood gas values, once every hour up to 24 hours postoperatively. Laboratory plasma glucose was additionally analyzed every 4 hours for reference value. Mean absolute differences were low between microdialysis and reference methods for both glucose and lactate values. All microdialysis glucose values were in the clinically acceptable zone of error grid analysis when compared with plasma glucose values. Accuracy of glucose values was 92% according to International Organization for Standardization criteria. Intravascular microdialysis is a novel and promising technique for real-time and accurate measurement of glucose and lactate during and after open heart surgery. Development of sensor technology may allow for continuous measurement of blood glucose and lactate using intravascular microdialysis.

Using an Online Image Analysis Technique to Characterize Sucrose Crystal Morphology during a Crystallization Run

The morphological forms and habits of crystals and agglomeration are important properties on crystallization processes. Online techniques for realtime measurement of these properties are mandatory for a better comprehension of crystal growth phenomenon. The present paper presents and describes a new online method to determine the complexity level of a crystal or a population of crystals during a crystallization process. An image analysis technique is combined with discriminant factorial analysis leading to results that allow the computation of the complexity of crystals through the parameter agglomeration degree of crystals. With this methodology, it has been possible to distinguish online and automatically among three different classes of crystals according to their complexity. It further describes the application of such methodology on the study of CaCl2, d-fructose, and d-glucose influence on the crystallization of sucrose, namely, on crystal size, morphology, and complexity. The effect of supersaturat...

Real-time measurement method of dc injection for transformerless PV systems

Measurement of dc injection is crucial for the transformerless PV systems. IEEE Std.929-2000 specifies that the PV systems shall not inject the dc current greater than 0.5% of the full rated output current. Dc injection measurement is not only useful for evaluating whether a transformerless PV system meets IEEE standards, but also for the effective dc suppression with injecting an equal but opposite dc component via a proper control scheme. In practice, however, it is difficult to extract the very low-level (0.5% I rated) dc currents in the presence of high levels of ac currents in transformerless PV systems. In order to overcome the limitation, this paper presents a real-time dc injection measurement technique. Some major issues such as the basic operating principle, frequency excursion effect mitigation and discrete-domain implementation of the proposed method are discussed. Theoretical analysis and performance evaluation results verify the effectiveness of the proposed dc injection measurement technique.