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Background: In-situ micro-computed tomography (µCT) technology is an attractive approach to investigate the evolution process of damage inside ceramic matrix composites (CMCs) during high-temperature service. The evolution process is highly time-sensitive under temperature-induced loads, and fast scanning is very necessary for in-situ µCT tests. Objective: The objective of this work is to provide a fast scanning method for in situ µCT tests on CMCs with complex microstructures by the innovation of a reconstruction algorithm. Method: To overcome the severe degradation of the reconstructed image quality resulting from sparse CT scans, a deep-learning-based multi-domain sparse reconstruction method was proposed. Three sub-networks including the projection-domain, image-domain, and fusion network were constructed in the multi-domain method to make full use of the information from the projection and image domain. Results: The proposed deep-learning-based sparse reconstruction method provided satisfactory µCT images on C/SiC composites with acceptable quality. The scanning time was reduced by 6 times. All selected evaluation metrics of the proposed method are higher than those of other single-domain methods and traditional iterative method. The segmentation accuracy of the µCT images obtained by the proposed method can meet the subsequent quantitative analysis. An in-situ tensile test of CMCs is conducted to further evaluate the performance in the practical application of in-situ experiments. The results indicate that the weak and thin micro-cracks can still be effectively retained and recovered. A detailed workflow to implement the method generally is also provided. Conclusions: Based on the deep-learning-based multi-domain sparse reconstruction method, the process of in-situ µCT tests can be greatly accelerated with little loss of the reconstructed image quality. [ABSTRACT FROM AUTHOR]

Abstract Background Highly sensitive digital total-body PET/CT scanners (uEXPLORER) have great potential for clinical applications and fundamental research. Given their increasing sensitivity, low-dose scanning or snapshot imaging is now possible in clinics. However, a standardized total-body 18F-FDG PET/CT protocol is still lacking. Establishing a standard clinical protocol for total-body 18F-FDG PET/CT examination under different activity administration plans can help provide a theoretical reference for nuclear radiologists. Methods The NEMA image quality (IQ) phantom was used to evaluate the biases of various total-body 18F-FDG PET/CT protocols related to the administered activity, scan duration, and iterations. Several objective metrics, including contrast recovery (CR), background variability (BV), and contrast-to-noise ratio (CNR), were measured from different protocols. In line with the European Association of Nuclear Medicine Research Ltd. (EARL) guidelines, optimized protocols were suggested and evaluated for total-body 18F-FDG PET/CT imaging for three different injected activities. Results Our NEMA IQ phantom evaluation resulted in total-body PET/CT images with excellent contrast and low noise, suggesting great potential for reducing administered activity or shortening the scan duration. Different to the iteration number, prolonging the scan duration was the first choice for achieving higher image quality regardless of the activity administered. In light of image quality, tolerance of oncological patients, and the risk of ionizing radiation damage, the 3-min acquisition and 2-iteration (CNR = 7.54), 10-min acquisition and 3-iteration (CNR = 7.01), and 10-min acquisition and 2-iteration (CNR = 5.49) protocols were recommended for full-dose (3.70 MBq/kg), half-dose (1.95 MBq/kg), and quarter-dose (0.98 MBq/kg) activity injection schemes, respectively. Those protocols were applied in clinical practices, and no significant differences were observed for the SUVmax of large/small lesions or the SUVmean of different healthy organs/tissues. Conclusion These findings support that digital total-body PET/CT scanners can generate PET images with a high CNR and low-noise background, even with a short acquisition time and low administered activity. The proposed protocols for different administered activities were determined to be valid for clinical examination and can maximize the value of this imaging type.

Background: Highly sensitive digital total-body PET/CT scanners (uEXPLORER) have great potential for clinical applications and fundamental research. Given their increasing sensitivity, low-dose scanning or snapshot imaging is now possible in clinics. However, a standardized total-body 18F-FDG PET/CT protocol is still lacking. Establishing a standard clinical protocol for total-body 18F-FDG PET/CT examination under different activity administration plans can help provide a theoretical reference for nuclear radiologists. Methods: The NEMA image quality (IQ) phantom was used to evaluate the biases of various total-body 18F-FDG PET/CT protocols related to the administered activity, scan duration, and iterations. Several objective metrics, including contrast recovery (CR), background variability (BV), and contrast-to-noise ratio (CNR), were measured from different protocols. In line with the European Association of Nuclear Medicine Research Ltd. (EARL) guidelines, optimized protocols were suggested and evaluated for total-body 18F-FDG PET/CT imaging for three different injected activities. Results: Our NEMA IQ phantom evaluation resulted in total-body PET/CT images with excellent contrast and low noise, suggesting great potential for reducing administered activity or shortening the scan duration. Different to the iteration number, prolonging the scan duration was the first choice for achieving higher image quality regardless of the activity administered. In light of image quality, tolerance of oncological patients, and the risk of ionizing radiation damage, the 3-min acquisition and 2-iteration (CNR = 7.54), 10-min acquisition and 3-iteration (CNR = 7.01), and 10-min acquisition and 2-iteration (CNR = 5.49) protocols were recommended for full-dose (3.70 MBq/kg), half-dose (1.95 MBq/kg), and quarter-dose (0.98 MBq/kg) activity injection schemes, respectively. Those protocols were applied in clinical practices, and no significant differences were observed for the SUVmax of large/small lesions or the SUVmean of different healthy organs/tissues. Conclusion: These findings support that digital total-body PET/CT scanners can generate PET images with a high CNR and low-noise background, even with a short acquisition time and low administered activity. The proposed protocols for different administered activities were determined to be valid for clinical examination and can maximize the value of this imaging type. [ABSTRACT FROM AUTHOR]

To improve the scanning speed of an atomic force microscopy (AFM), a smooth scanning pattern is elaborately devised via trajectory shaping in this paper, so as to achieve fast imaging without hardware modification. Specifically, in the proposed scanning method, the piezoelectric actuator tracks a well-designed smooth periodic signal in x-direction, and simultaneously tracks a step signal in y-direction. The advantage of the proposed method is that it does not require additional data reprocessing to construct the morphology of the sample surface, while significantly increasing the scanning bandwidth restricted by the raster scanning method. Particularly, to directly utilize the height data collected by scanning to produce the sample morphology, the forward process in the common raster scanning mode is retained in the proposed method, the tracking signal in the forward process is thus set to a ramp function in x-direction. In addition, to ensure the continuity and smoothness of the entire tracking signal in x-direction, a segment of a sine curve is uniquely determined as the backward tracking signal by position and acceleration constraints, so as to ensure that the forward and backward curves are continuous and acceleration-continuous at the intersection point. Moreover, the frequency spectrum analysis of the designed smooth signal is carried out to exhibit the depressed amplitudes of high-frequency components, which demonstrates that the proposed method is able to reduce the resonance in AFM high-speed scanning, so as to improve the capacity of rapidly generating high-quality images. Finally, convincing comparison experiments are implemented to verify the imaging performance of the designed scanning algorithm. [ABSTRACT FROM AUTHOR]

The work is devoted to the study of scanning the transverse profile of a beam using a vibrating wire. A new algorithm has been developed that allows the use of a resonant vibrating target method for high scanning speeds. The method is based on the idea of measuring secondary/reflected particles/radiation generated from the interaction of the beam particles with the wire material, synchronously with the frequency of the wire oscillation. The proposed algorithm for using a differential signal with sign inversion on consecutive measurements from half-periods of wire oscillations is generalized for the case when the scanning speed is much higher than the average speed of the wire oscillation. [ABSTRACT FROM AUTHOR]

Photoacoustic endoscopy offers in vivo examination of the visceral tissue using endogenous contrast, but its typical B-scan rate is ~10 Hz, restricted by the speed of the scanning unit and the laser pulse repetition rate. Here, we present a transvaginal fast-scanning optical-resolution photoacoustic endoscope with a 250-Hz B-scan rate over a 3-mm scanning range. Using this modality, we not only illustrated the morphological differences of vasculatures among the human ectocervix, uterine body, and sublingual mucosa but also showed the longitudinal and cross-sectional differences of cervical vasculatures in pregnant women. This technology is promising for screening the visceral pathological changes associated with angiogenesis. [ABSTRACT FROM AUTHOR]

A leukocyte image fast scanning method based on max-min distance clustering is proposed. Because of the lower proportion and uneven distribution of leukocytes in human peripheral blood, there will not be any leukocyte in lager quantity of the captured images if we directly scan the blood smear along an ordinary zigzag scanning routine with high power (100x) objective. Due to the larger field of view of low power (10x) objective, the captured low power blood smear images can be used to locate leukocytes. All of the located positions make up a specific routine, if we scan the blood smear along this routine with high power objective, there will be definitely leukocytes in almost all of the captured images. Considering the number of captured images is still large and some leukocytes may be redundantly captured twice or more, a leukocyte clustering method based on max–min distance clustering is developed to reduce the total number of captured images as well as the number of redundantly captured leukocytes. This method can improve the scanning efficiency obviously. The experimental results show that the proposed method can shorten scanning time from 8.0–14.0min to 2.5–4.0min while extracting 110 nonredundant individual high power leukocyte images.

A leukocyte image fast scanning method based on max-min distance clustering is proposed. Because of the lower proportion and uneven distribution of leukocytes in human peripheral blood, there will not be any leukocyte in lager quantity of the captured images if we directly scan the blood smear along an ordinary zigzag scanning routine with high power (100 x) objective. Due to the larger field of view of low power (10 x) objective, the captured low power blood smear images can be used to locate leukocytes. All of the located positions make up a specific routine, if we scan the blood smear along this routine with high power objective, there will be definitely leukocytes in almost all of the captured images. Considering the number of captured images is still large and some leukocytes may be redundantly captured twice or more, a leukocyte clustering method based on max-min distance clustering is developed to reduce the total number of captured images as well as the number of redundantly captured leukocytes. This method can improve the scanning efficiency obviously. The experimental results show that the proposed method can shorten scanning time from 8.0-14.0min to 2.5-4.0min while extracting 110 nonredundant individual high power leukocyte images. [ABSTRACT FROM AUTHOR]

A novel, intensity-stabilized, fast-scanned, direct absorption spectroscopy (IS-FS-DAS) instrumentation, based on a distributed feedback (DFB) diode laser, is developed. A fiber-coupled polarization rotator and a fiber-coupled polarizer are used to stabilize the intensity of the laser, which significantly reduces its relative intensity noise (RIN). The influence of white noise is reduced by fast scanning over the spectral feature (at 1 kHz), followed by averaging. By combining these two noise-reducing techniques, it is demonstrated that direct absorption spectroscopy (DAS) can be swiftly performed down to a limit of detection (LOD) (1σ) of 4 × 10−6, which opens up a number of new applications. [ABSTRACT FROM AUTHOR]

A novel, intensity-stabilized, fast-scanned, direct absorption spectroscopy (IS-FS-DAS) instrumentation, based on a distributed feedback (DFB) diode laser, is developed. A fiber-coupled polarization rotator and a fiber-coupled polarizer are used to stabilize the intensity of the laser, which significantly reduces its relative intensity noise (RIN). The influence of white noise is reduced by fast scanning over the spectral feature (at 1 kHz), followed by averaging. By combining these two noise-reducing techniques, it is demonstrated that direct absorption spectroscopy (DAS) can be swiftly performed down to a limit of detection (LOD) (1σ) of 4 × 10−6, which opens up a number of new applications. [ABSTRACT FROM AUTHOR]

For nearly all atomic force microscopies (AFMs) utilized now, only the signals in trace scanning process are employed to reconstruct the sample surface topography, while the data of retrace scanning process are just used for adjustment. In this paper, a novel trace and retrace scanning combined (TRSC) topography reconstruction strategy, which successfully utilizes data from both trace and retrace processes, is proposed for AFMs to increase the surface reconstruction accuracy. Specifically, two reconstructed topography images are obtained, one is for trace scanning, and the other is for retrace scanning; the hysteresis distortion is successfully compensated with a data fusion-based postprocessing method; the alignment for trace and retrace images is further guaranteed with a feature point-based strategy; then the two images are combined together with confidence levels to reconstruct the final accurate topography image. Compared with the conventional scanning method, the proposed TRSC imaging algorithm provides much more accurate image for the sample surface, and it is especially valid for high-speed scanning tasks. Some simulation and experimental results are included to demonstrate the superior performance of the proposed imaging method. [ABSTRACT FROM PUBLISHER]

An increasing number of studies are focusing on the detection and investigation of nanometer-sized particles. One important tool is the Scanning Mobility Particle Sizer (SMPS). In the case of dynamic processes like nucleation events, the lower detection threshold as well as the measurement time are important system parameters. High accuracy of the applied voltage as a function of time during fast scanning is required. Short scan times additionally yield a broadening and smearing of the measured size distribution. Here, the performance of the Nano-SMPS using the new TSI classifier (TSI 3082) in combination with either the nano water condensation particle counter (TSI 3788) or the ultrafine condensation particle counter (TSI 3776) was investigated. The focus of this work is the performance of the system at the lower detection limit as a function of the scan time. Fast scan times as short as 3 s were tested. The reproducibility of the aerosol size distribution and number concentration for different distributions and materials was investigated. The tested substances included different proteins, sucrose and polystyrene latex reference particles. The sizing reproducibility and accuracy for all tested scan times was within 3%. The measured total number concentration was captured with a precision of ±3% for all tested scan times. [ABSTRACT FROM AUTHOR]

A novel, intensity-stabilized, fast-scanned, direct absorption spectroscopy (IS-FS-DAS) instrumentation, based on a distributed feedback (DFB) diode laser, is developed. A fiber-coupled polarization rotator and a fiber-coupled polarizer are used to stabilize the intensity of the laser, which significantly reduces its relative intensity noise (RIN). The influence of white noise is reduced by fast scanning over the spectral feature (at 1 kHz), followed by averaging. By combining these two noise-reducing techniques, it is demonstrated that direct absorption spectroscopy (DAS) can be swiftly performed down to a limit of detection (LOD) (1σ) of 4 × 10−6, which opens up a number of new applications.

Abstract: A fast method that can be used to classify unknown jet fuel types or detect possible property changes in jet fuel physical properties is of paramount interest to national defense and the airline industries. While fast gas chromatography (GC) has been used with conventional mass spectrometry (MS) to study jet fuels, fast GC was combined with fast scanning MS and used to classify jet fuels into lot numbers or origin for the first time by using fuzzy rule-building expert system (FuRES) classifiers. In the process of building classifiers, the data were pretreated with and without wavelet transformation and evaluated with respect to performance. Principal component transformation was used to compress the two-way data images prior to classification. Jet fuel samples were successfully classified with 99.8±0.5% accuracy for both with and without wavelet compression. Ten bootstrapped Latin partitions were used to validate the generalized prediction accuracy. Optimized partial least squares (o-PLS) regression results were used as positively biased references for comparing the FuRES prediction results. The prediction results for the jet fuel samples obtained with these two methods were compared statistically. The projected difference resolution (PDR) method was also used to evaluate the fast GC and fast MS data. Two batches of aliquots of ten new samples were prepared and run independently 4 days apart to evaluate the robustness of the method. The only change in classification parameters was the use of polynomial retention time alignment to correct for drift that occurred during the 4-day span of the two collections. FuRES achieved perfect classifications for four models of uncompressed three-way data. This fast GC/fast MS method furnishes characteristics of high speed, accuracy, and robustness. This mode of measurement may be useful as a monitoring tool to track changes in the chemical composition of fuels that may also lead to property changes. [ABSTRACT FROM AUTHOR]

Abstract: We have studied frictional force and wear problem in real-time atomic force microscopy in contact-mode using a resonator type mechanical scanner allegedly reported. The fast scanning may cause wear in the sample surface or the tip, and may deteriorate the image quality. Mineral oil was used to make a lubricious surface on a polycarbonate sample, and it was found that the interfacial frictional force was decreased. A Si tip which was coated with a hydrophobic film by means of chemical modification was confirmed to diminish the frictional force in the fast scanning process. The resultant image quality was improved due to reduced friction and wear. [Copyright &y& Elsevier]

Differential scanning calorimetry (DSC) is an effective analytical tool to characterize the physical properties of a polymer. DSC enables determination of melting, crystallization, and mesomorphic transition temperatures, and the corresponding enthalpy and entropy changes, and characterization of glass transition and other effects that show either changes in heat capacity or a latent heat. Calorimetry takes a special place among other methods. In addition to its simplicity and universality, the energy characteristics (heat capacity CP and its integral over temperature T—enthalpy H), measured via calorimetry, have a clear physical meaning even though sometimes interpretation may be difficult. With introduction of differential scanning calorimeters (DSC) in the early 1960s calorimetry became a standard tool in polymer science. The advantage of DSC compared with other calorimetric techniques lies in the broad dynamic range regarding heating and cooling rates, including isothermal and temperature-modulated operation. Today 12 orders of magnitude in scanning rate can be covered by combining different types of DSCs. Rates as low as 1 μK s−1 are possible and at the other extreme heating and cooling at 1 MK s−1 and higher is possible. The broad dynamic range is especially of interest for semicrystalline polymers because they are commonly far from equilibrium and phase transitions are strongly time (rate) dependent. Nevertheless, there are still several unsolved problems regarding calorimetry of polymers. I try to address a few of these, for example determination of baseline heat capacity, which is related to the problem of crystallinity determination by DSC, or the occurrence of multiple melting peaks. Possible solutions by using advanced calorimetric techniques, for example fast scanning and high frequency AC (temperature-modulated) calorimetry are discussed. [ABSTRACT FROM AUTHOR]

Abstract: A novel design of a scanning unit for atomic force microscopy (AFM) is presented that enables scanning speeds three orders of magnitude faster than compared to conventional AFMs. The new scanner is designed for high mechanical resonance frequencies, based on a new scanner design, which is optimized using finite element analysis. For high-speed scanning a new controller, based on input-shaping techniques, has been developed that reduces imaging artifacts due to the scanner’s dynamics. The implementation of the new AFM system offers imaging capabilities of several thousand lines per second with a scanning range of 13μm in both scanning directions, and the freedom to choose the fast scan-axis in any arbitrary direction in the X–Y-plane. [Copyright &y& Elsevier]

A new mechanical scanner design for a high-speed atomic force microscope (AFM) is presented and discussed in terms of modeling and control. The positioning range of this scanner is 13 μm in the X- and Y-directions and 4.3 μm in the vertical direction. The lowest resonance frequency of this scanner is above 22 kHz. This paper is focused on the vertical direction of the scanner, being the crucial axis of motion with the highest precision and bandwidth requirements for gentle imaging with the AFM. A second- and a fourth-order mathematical model of the scanner are derived that allow new insights into important design parameters. Proportional-integral (PI)-feedback control of the high-speed scanner is discussed and the performance of the new AFM is demonstrated by imaging a calibration grating and a biological sample at 8 frames/s. [ABSTRACT FROM AUTHOR]

Fast and precise positioning is a basic requirement for nanotechnology applications. Many scanning-probe microscopes (SPM) use a piezoelectric tube scanner for actuation with nanometer resolution in all three spatial directions. Due to the dynamics of the actuator, the imaging speed of the SPM is limited. By applying model-based open-loop control, the dynamic behavior of the scanner can be compensated, reducing the displacement error, topographical artifacts, modulation of the interaction force, and modulation of the relative tip-sample velocity. The open-loop controlled system enables imaging of up to 125-/~m-sized samples at a line scan rate of 122 Hz, which is about 15 times faster than the commercial system. [ABSTRACT FROM AUTHOR]

The imaging speed of atomic force microscopy (AFM) is limited due to the dynamics of the piezo scanner along the scanning direction. This article presents the identification and open-loop control of a piezoelectric tube scanner to enable fast imaging. By applying a model based open-loop control the dynamic behaviour of the piezo tube can be compensated. The lateral displacement error is reduced and topographical artifacts, additional cantilever deflection, modulation of the tip–sample interaction force, and modulation of the relative tip–sample velocity vanish. The open-loop controlled AFM scanner enables imaging at a line scan rate of 122 Hz, which is about 15 times faster than standard systems. [Copyright &y& Elsevier]

In this work, a method is presented which allows the determination of calorimetric information, and thus, information about the precipitation and dissolution behavior of aluminum alloys during heating rates that could not be previously measured. Differential scanning calorimetry (DSC) is an established method for in-situ recording of dissolution and precipitation reactions in various aluminum alloys. Diverse types of DSC devices are suitable for different ranges of scanning rates. A combination of the various available commercial devices enables heating and cooling rates from 10−4 to 5 Ks−1 to be covered. However, in some manufacturing steps of aluminum alloys, heating rates up to several 100 Ks−1 are important. Currently, conventional DSC cannot achieve these high heating rates and they are still too slow for the chip-sensor based fast scanning calorimetry. In order to fill the gap, an indirect measurement method has been developed, which allows the determination of qualitative information, regarding the precipitation state, at various points of any heat treatment. Different rapid heat treatments were carried out on samples of an alloy EN AW-6082 in a quenching dilatometer and terminated at defined temperatures. Subsequent reheating of the samples in the DSC enables analysis of the precipitation state of the heat-treated samples. This method allows for previously un-measurable heat treatments to get information about the occurring precipitation and dissolution reactions during short-term heat treatments. [ABSTRACT FROM AUTHOR]

Photoacoustic imaging (PAI) has many interesting advantages, such as deep imaging depth, high image resolution, and high contrast to intrinsic and extrinsic chromophores, enabling morphological, functional, and molecular imaging of living subjects. Photoacoustic microscopy (PAM) is one form of the PAI inheriting its characteristics and is useful in both preclinical and clinical research. Over the years, PAM systems have been evolved in several forms and each form has its relative advantages and disadvantages. Thus, to maximize the benefits of PAM for a specific application, it is important to configure the PAM system optimally by targeting a specific application. In this review, we provide practical methods for implementing a PAM system to improve the resolution, signal-to-noise ratio (SNR), and imaging speed. In addition, we review the preclinical and the clinical applications of PAM and discuss the current challenges and the scope for future developments., Competing Interests: None.