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In Robot Assisted Minimally Invasive Surgery, discriminating critical subsurface structures is essential to make the surgical procedure safer and more efficient. In this paper, a novel robot assisted electrical bio-impedance scanning (RAEIS) system is developed and validated using a series of experiments. The proposed system constructs a tri-polar sensing configuration for tissue homogeneity inspection. Specifically, two robotic forceps are used as electrodes for applying electric current and measuring reciprocal voltages relative to a ground electrode which is placed distal from the measuring site. Compared to the other existing electrical bioimpedance sensing technology, the proposed system is able to use miniaturized electrodes to measure a site flexibly with enhanced subsurfacial detection capability. In this paper, we present the concept, the modeling of the sensing method, the hardware design, and the system calibration. Subsequently, a series of experiments are conducted for system evaluation including finite element simulation, saline solution bath experiments and experiments based on ex vivo animal tissues. The experimental results demonstrate that the proposed system can measure the resistivity of the material with high accuracy, and detect a subsurface non-homogeneous object with 100% success rate. The proposed parameters estimation algorithm is able to approximate the resistivity and the depth of the subsurface object effectively with one fast scanning.

T-cells are immune cells that continuously scan for foreign-derived antigens on the surfaces of nearly all cells, termed antigen presenting cells (APCs). They do this by dynamically extending numerous protrusions called microvilli (MV) that contain T-cell receptors (TCRs) towards the APC surface in order to scan for antigens. The number, size, and dynamics of these MV, and the complex multi-scale topography that results, play a yet unknown role in antigen recognition. We develop an anatomically informed model of the T-cell/APC interface to elucidate the role of MV dynamics in antigen sensitivity and discrimination. We find that MV surveillance reduces antigen sensitivity compared to a completely flat interface unless MV are stabilized in an antigen-dependent manner and find that MV have only a modest impact on antigen discrimination. The model highlights that MV contacts optimise the competing demands of fast scanning speeds of the APC surface with antigen sensitivity and that T-cells operate their MV near the interface packing limit. Finally, we find that observed MV contact lifetimes can be largely influenced by conditions in the T-cell/APC interface with these lifetimes often being longer than the simulation or experimental observation period. The work highlights the role of MV in antigen recognition.Significance StatementT-cells search for foreign-derived antigens on the surface of antigen presenting cells (APC) by dynamically extending tubular protrusions called microvilli (MV) which form membrane close-contacts. Although known for decades, their role in antigen recognition remains unclear. Guided by recent experiments, we built an anatomically informed stochastic model of MV scanning and compared with a topologically flat interface. We find that MV scanning modestly impacts antigen discrimination, yet it enables T-cells to balance the competing effects of maintaining sensitivity while conducting rapid APC surveillance. The model can reconcile discrepancies in observed MV lifetimes and demonstrates that observed area coverage fractions correspond to geometric packing limits. Our work suggests that MVs promote positive signaling outcomes despite anatomical constraints to close contact formation.

Purpose Scanning projection-based stereolithography (SPSL) is a powerful technology for additive manufacturing with high resolution as well as large building area. However, the surface quality of stitching boundary in an SPSL system has been rarely studied, and no positive settlement was proposed to address the poor stitching quality. This paper aims to propose an approach of multi-pass scanning and a compensation algorithm for multi-pass scanning process to address the issue of poor stitching quality in SPSL systems. Design/methodology/approach The process of multi-pass scanning is realized by scanning regions repeatedly, and the regions can be cured simultaneously because of the very short repeat exposure time and very fast scanning. Then, the poor stitching quality caused by the non-simultaneous curing can be eliminated. Also, a compensation algorithm is designed for multi-pass scanning to reduce the stitching errors. The validity of multi-pass scanning is verified by curing depth test, while the performance of multi-pass scanning as well as proposed compensation algorithm is demonstrated by comparing with that of a previous SPSL system. Findings The results lead to a conclusion that multi-pass scanning with its compensation algorithm is an effective approach to improve the stitching quality of an SPSL system. Practical implications This study can provide advice for researchers to achieve the satisfactory surface finish with SPSL technology. Originality/value The authors proposed a process of multi-pass scanning as well as a compensation algorithm for SPSL additive manufacturing (system to improve the stitching quality, which has rarely been studied in previous work.

Ultrasound phantoms are commonly used to assess the performance of ultrasound systems and ensure their proper functionality, in addition to providing opportunities for medical training. However, Focused Assessment with Sonography for Trauma (FAST) phantoms, in particular, are prohibitively expensive and procedure specific. This work explores the use of additive manufacturing to fabricate a patient-specific, full-scale torso ultrasound phantom. Phantom geometry was derived from anonymized computed tomography scans and segments into discrete organs. The digital organs (torso, skeleton, liver, spleen) were 3-D printed and used as castable molds for producing their respective body features. These organs were integrated with artificial hemorrhages to produce a realistic training tool for FAST scans. The resulting phantom is low in cost, has a verified shelf-life of at least 1 y and was positively reviewed by a trauma and emergency radiologist for its ability to provide accurate geometric and ultrasound information.

Obtaining high-resolution scans of bones and joints for clinical applications is challenging. HR-pQCT is considered the best technology to acquire high-resolution images of the peripheral skeleton in vivo, but a breakthrough for widespread clinical applications is still lacking. Recently, we showed on trapezia that CBCT is a promising alternative providing a larger FOV at a shorter scanning time. The goals of this study were to evaluate the accuracy of CBCT in quantifying trabecular bone microstructural and predicted mechanical parameters of the distal radius, the most often investigated skeletal site with HR-pQCT, and to compare it with HR-pQCT. Nineteen radii were scanned with four scanners: (1) HR-pQCT (XtremeCT, Scanco Medical AG, @ (voxel size) 82 μm), (2) HR-pQCT (XtremeCT-II, Scanco, @60.7 μm), (3) CBCT (NewTom 5G, Cefla, @75 μm) reconstructed and segmented using in-house developed software and (4) microCT (VivaCT40, Scanco, @19 μm-gold standard). The following parameters were evaluated: predicted stiffness, strength, bone volume fraction (BV/TV) and trabecular thickness (Tb.Th), separation (Tb.Sp) and number (Tb.N). The overall accuracy of CBCT with in-house optimized algorithms in quantifying bone microstructural parameters was comparable (R2 = 0.79) to XtremeCT (R2 = 0.76) and slightly worse than XtremeCT-II (R2 = 0.86) which were both processed with the standard manufacturer's technique. CBCT had higher accuracy for BV/TV and Tb.Th but lower for Tb.Sp and Tb.N compared to XtremeCT. Regarding the mechanical parameters, all scanners had high accuracy (R2 [Formula: see text] 0.96). While HR-pQCT is optimized for research, the fast scanning time and good accuracy renders CBCT a promising technique for high-resolution clinical scanning. ispartof: Calcified Tissue International vol:108 issue:3 pages:314-323 ispartof: location:United States status: published

The bead foaming of semicrystalline polymers is a complex thermal process involving the formation of multiple crystalline populations, which serve the dual purposes of ensuring the structural integrity of beads while also allowing bead sintering at the interface. The quality of this "double melting peak" structure is determined by the temperature and duration of the isothermal treatment of the beads as well as the quenching rate following the isotherm. Currently, the intricacies of the quenching process are not very well-known due to the challenge of replicating these rapid cooling rates in a laboratory setting. Fast-scanning calorimetry was used to reproduce these conditions for isotactic polypropylene (iPP), revealing optimal quenching rates for the bead foaming of iPP. We further probed these thermal features using two-dimensional correlation analysis as a tool to understand the dynamics, interdependence, and relative contributions of multiple thermal events such as glass transition, mesophase formation, cold crystallization, and melting in response to the perturbation of the quenching rate.

Fast scanning calorimetry (FSC) is an effective analytical tool to characterize the thermal properties of polymers. Heating rates up to 100 000 K/s allow studies at time scales inaccessible with conventional calorimeters, whose rates are typically less than about 0.5 K/s. Recent studies have successfully demonstrated methods for obtaining quantitative analysis of thermal properties of polymer samples using chip-based FSC. Therefore very small sample sizes, such as particles or nonwovens, can be characterized. In this study, we investigated the thermal properties of poly(L-lactide) PLLA with FSC compared to the results from standard DSC methods. PLLA specimens were fabricated via solution casting and needle electrospinning. The results suggest a significant influence of heating rates on the melting temperature of PLLA. The results show that different fabrication methods lead to changes in crystallinity and that FSC results are not completely comparable with standard DSC measurements.

Control of non-metallic inclusions is essential for the production of high-quality steel. This review summarizes processes that change inclusion compositions and concentrations during secondary steelmaking—slower changes are limited by reaction between bulk steel and slag or refractory, and faster changes involve direct additions to the steel bath. An example of the former is conversion of alumina inclusions to spinels during ladle treatment, while reoxidation and calcium treatment are typical exemplars of the fast changes. For the slower changes, inclusions approach equilibrium with the liquid steel and conceptually simple kinetic models correctly describe inclusion evolution during ladle treatment. Disequilibrium from faster changes persists for several minutes under typical ladle conditions, with small-scale inhomogeneity in the steel. Fast scanning electron microscopy with microanalysis has facilitated detailed study of these inclusion evolution processes by providing information on inclusion composition, size, and shape. Machine learning methods are likely to be increasingly important in analysis of the results. Such methods have already shown promise to improve classification of inclusions and recognizing inclusion clusters, from analyses of polished sections. Several unresolved issues that require future study are noted.

Homogeneous crystal nucleation in polyamide 66 (PA 66) was studied by a combination of atomic-force microscopy (AFM) and fast-scanning chip calorimetry (FSC), with a specific experimental setup all...

One puzzling phenomenon in glass physics is the so-called ‘shadow glass transition’ which is an anomalous heat-absorbing process below the real glass transition and influences glass properties. However, it has yet to be entirely characterized, let alone fundamentally understood. Conventional calorimetry detects it in limited heating rates. Here, with the chip-based fast scanning calorimetry, we study the dynamics of the shadow glass transition over four orders of magnitude in heating rates for 24 different hyper-quenched metallic glasses. We present evidence that the shadow glass transition correlates with the secondary (β) relaxation: (i) The shadow glass transition and the β relaxation follow the same temperature–time dependence, and both merge with the primary relaxation at high temperature. (ii) The shadow glass transition is more obvious in glasses with pronounced β relaxation, and vice versa; their magnitudes are proportional to each other. Our findings suggest that the shadow glass transition signals the thermodynamics of β relaxation in hyper-quenched metallic glasses., A puzzling shadow glass transition, prior to the real glass transition, is disclosed to correlate with the secondary relaxation in metallic glasses.

In this article, a systematic framework for designing the control for fine positioning (scanning) stages of X-ray microscopes is presented. This framework facilitates designs that simultaneously achieve specifications on positioning resolution and tracking bandwidth while guaranteeing robustness of the closed loop device to unmodeled uncertainties. We use robust optimal control techniques for modeling, quantifying design objectives and system-specific challenges, and designing the control laws. The control designs were implemented on a three degree of freedom piezoactuated flexure stages dedicated for fine positioning of X-ray optics. Experimental results demonstrate significant improvements in positioning performance of 134%, 150%, and 132% in tracking bandwidths along the lateral ( X ), vertical ( Y ), and beam ( Z ) directions, respectively, when compared to proportional–integral–derivative controller designs. This was achieved while keeping similar or better positioning resolution and robustness measures. Fast scanning for X-ray imaging was demonstrated in both the step scan and flyscan modes, where bandwidth was improved by over 450 times with flyscan compared to the step scan.

Photoacoustic (PA) microscopy (PAM) has achieved remarkable progress in biomedicine in the past decade. It is a fast-rising imaging modality with diverse applications, such as hemodynamics, oncology, metabolism, and neuroimaging. Combining optical excitation and acoustic detection, the hybrid nature of PAM provides advantages of rich contrast and deep penetration. In recent years, high-speed PAM has flourished and enabled high-speed wide-field imaging of functional activity. In this review, we summarize the most recent advances in high-speed PAM technologies, including high-repetition-rate multi-wavelength laser development, fast scanning techniques, and novel PA signal acquisition strategies.

A new approach for designing antenna and feeder systems of meteorological radar which is inexpensive, fast scanning, dual polarization and phased array is proposed. This goal has been accomplished by a new technique, based on a special series and parallel feed network, to realize the scanning pattern with high gain and low side-lobe level. In this technique, the number of antenna elements, which can satisfy performances of radar, is significantly decreased to 2/3 of original scope. As a proof, a P-band tropospheric wind profiler radar, which has a 169¬element array and 13 feed networks with 30dB gain and - 30dB low side-lobe level, is presented. The simulation and measured results are presented, and performances are excellent.

This paper addresses efficient frequency domain sampling techniques for faster Terahertz (THz) synthetic aperture radar (SAR) imaging. While the large available absolute bandwidths in the frequency range beyond 100 GHz enable very high resolution imaging techniques, sampling times e.g. in stepped continuous wave systems increase due to the large number of samples. Of course, fast scanning can be achieved by larger frequency steps but this comes at the cost of a smaller unambiguous range accessible to the measurement system. Especially in case of complex targets that are to be imaged, this can be a challenge. We propose, compare and discuss different sampling schemes in the frequency domain with non-equidistant frequency steps. The discussion is validated by measurements using a vector network analyzer (VNA) SAR imaging setup operating between 260 GHz and 400 GHz.

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.

In nanoparticles embedded in an Al-rich polycrystalline matrix have been investigated concerning the kinetics of their melting behavior. The advantage of the present system lies in the fact, that two distinct populations of particles are intrinsically formed: facetted nanoparticles that are embedded within the matrix grains and that obey the facetted Wulff shape or slight deviations thereof and particles situated at the grain boundaries of the matrix that form curved interfaces with the matrix grains. This second fraction thus serves as an internal reference, since the particles at the grain boundaries melt at the bulk melting temperature. Utilizing an averaging procedure for the fast scanning calorimetry measurements and combining conventional differential scanning- and fast scanning calorimetry with microstructure investigations, we found strong evidence for the observation of a heating-rate dependence of the melting transformation of the matrix-embedded nanoparticles. This observation gives rise to discuss the kinetics of melting in cases where the most potent nucleant for melting, the surface, is deactivated.

Fast scanning calorimetry (FSC) was applied for measurements of the sublimation rates of theophylline, caffeine and anthraquinone as reference compounds. In comparison to conventional vapor pressure determination techniques, this method requires only nano-gram-size samples. The increased surface to volume ratio allows for very high sublimation rates and makes the sublimation process dominant over a possible decomposition. Experimental conditions and data treatment have been elaborated and validated by comparison with reliable literature data. The FSC method “opens a new door” for reliable experimental determination of vapor pressures and sublimation enthalpies for very low volatile and thermally unstable compounds like bio-relevant molecules.

Background: Imaging is an integral part of trauma management and the huge burden of trauma in South Africa places substantial pressures on radiology resources. This study aims to provide a holistic overview of the burden of trauma imaging and the cost of trauma to a busy CT scanning facility at a tertiary hospital in South Africa. Methods: We set out to describe and quantify the impact of blunt poly-trauma on CT scanning services at Grey’s Hospital in Pietermaritzburg. We aimed to provide a holistic assessment in terms of use of equipment and staff, cost to the hospital and overall usage of CT scanning. Results: Over the four-year study period, 1572 patients required a CT scan following blunt torso trauma (mean age: 30 years, 81% males). Of the 1572 patients, 625 had a chest radiograph (40%), 383 a cervical spine X-ray (24%), 347 a pelvic X-ray (22%), 292 a skull X-ray (18%), 193 a limb X-ray (12%), 133 an abdominal radiograph (8%), and 86 a FAST scan (5%). The 1572 CT included: 967 head, 568 neck, 65 chest, 241 abdominal, 228 pelvic, 12 upper limb, 38 lower limb and 394 had full body (Pan) CT scan. The mean total cost of the CT scanning for blunt poly-trauma is ZAR 12 000. The total cost of CT scanning for blunt poly-trauma is 0.92% of the total hospital expenditure. Roughly 7.8% of the total hours worked by the CT scanner over the time period under review was dedicated to blu nt poly-trauma. Conclusion: Blunt poly-trauma is a preventable disease, which has a major financial impact on the healthcare system in general. This study has documented the tremendous burden it places on an already stretched CT scanning service.

In this paper, we propose a novel static CT system: triple planes CT (TPCT) system. Three source-detector planes in different horizontal directions are placed in the system. Line-array carbon nanotube sources with different voltages and sandwich detectors are used. Compared to conventional cone-beam CT and common inverse-geometry CT, the TPCT enables fast scanning and six-energy imaging. 1-D U-Net is applied to correct the severe scatter caused by the special geometry. The limited-view problem is solved by the hybrid reconstruction algorithm. A Monte-Carlo simulation is performed on a thorax phantom. Both the reconstruction results and decomposition results have good image quality and show the feasibility of our proposed TPCT imaging system.

In this study, we developed a line-field Fourier domain optical coherence tomography (LF-FDOCT) system that performs lateral scanning using a two-dimension spatial light modulator and detects multiple channels of spectral domain OCT signal in parallel using a two-dimensional sensor. The LF-FDOCT system eliminates the need for mechanical scanning to acquire volumetric OCT data. It allows parallel acquisition of signal for B mode scan imaging through snapshot detection and offers unprecedented flexibility to select a fast scanning dimension. In this work, we describe the principle of LF-FDOCT imaging and present experimental results to demonstrate the effectiveness of this technology.

We present a multi-species trace gas sensor based on a broadband mid-infrared supercontinuum source and a compact home-built Fourier Transform Spectrometer with a balanced detection scheme. The gas sensor provides a spectral resolution of 1 GHz in the wavelength range of 2.4-4.2 µm. Using a global fitting routine, we are able to retrieve the concentrations of different species in complex gas mixtures, achieving detection sensitivities in the order of 100 ppbv.Hz-1/2 (4s measurement time). We used the sensor to measure volatiles from fruit (apples, pears) under storage conditions, demonstrating its potential for monitoring fruit in commercial storage facilities.

Purpose: To assess image quality and uncertainty in organ-at-risk segmentation on cone beam computed tomography (CBCT) enhanced by deep-learning convolutional neural network (DCNN) for head and neck cancer.Methods: An in-house DCNN was trained using forty post-operative head and neck cancer patients with their planning CT and first-fraction CBCT images. Additional fifteen patients with repeat simulation CT (rCT) and CBCT scan taken on the same day (oCBCT) were used for validation and clinical utility assessment. Enhanced CBCT (eCBCT) images were generated from the oCBCT using the in-house DCNN. Quantitative imaging quality improvement was evaluated using HU accuracy, signal-to-noise-ratio (SNR), and structural similarity index measure (SSIM). Organs-at-risk (OARs) were delineated on o/eCBCT and compared with manual structures on the same day rCT. Contour accuracy was assessed using dice similarity coefficient (DSC), Hausdorff distance (HD), and center of mass (COM) displacement. Qualitative assessment of users’ confidence in manual segmenting OARs was performed on both eCBCT and oCBCT by visual scoring.Results: eCBCT organs-at-risk had significant improvement on mean pixel values, SNR (p < 0.05), and SSIM (p < 0.05) compared to oCBCT images. Mean DSC of eCBCT-to-rCT (0.83 ± 0.06) was higher than oCBCT-to-rCT (0.70 ± 0.13). Improvement was observed for mean HD of eCBCT-to-rCT (0.42 ± 0.13 cm) vs. oCBCT-to-rCT (0.72 ± 0.25 cm). Mean COM was less for eCBCT-to-rCT (0.28 ± 0.19 cm) comparing to oCBCT-to-rCT (0.44 ± 0.22 cm). Visual scores showed OAR segmentation was more accessible on eCBCT than oCBCT images.Conclusion: DCNN improved fast-scan low-dose CBCT in terms of the HU accuracy, image contrast, and OAR delineation accuracy, presenting potential of eCBCT for adaptive radiotherapy.

This article belongs to the Special Issue Recent Developments on Calorimetry and Thermal Analysis of Polymers and Nanocomposites., The present work aims to provide insights on recent findings indicating the presence of multiple equilibration mechanisms in physical aging of glasses. To this aim, we have investigated a glass forming polyether, poly(1-4 cyclohexane di-methanol) (PCDM), by following the evolution of the enthalpic state during physical aging by fast scanning calorimetry (FSC). The main results of our study indicate that physical aging persists at temperatures way below the glass transition temperature and, in a narrow temperature range, is characterized by a two steps evolution of the enthalpic state. Altogether, our results indicate that the simple old-standing view of physical aging as triggered by the α relaxation does not hold true when aging is carried out deep in the glassy state., D.C. research was funded by MICINN-Spain and FEDER-UE, grant PGC2018-094548-B-I00; and the Basque Government, grant IT-1175-19. J.M. thanks MICINN /FEDER for grant Ref. PGC2018-094620-A-I00.

Magnetic resonance fingerprinting (MRF) is a powerful quantitative imaging technique that allows simultaneous measurement of multiple tissue properties in a single and time-efficient scan. Its innovation comes from a fundamentally different way of designing MR acquisition, reconstruction, and quantification, which attracts widespread active research for technical development and clinical translation. A growing number of studies have demonstrated robust implementation, fast scan time and high reproducibility of MRF scans in a clinical setting. Clinical applications of MRF in different parts of the body have also started to show promising results for disease diagnosis and monitoring. This chapter will review the basic concept, implementation, and current neural imaging applications of the MRF technology.

The identification of explosives residue and other harmful materials in field is a key problem to solve for world safety. Here we present a point-by-point imaging technique based on stand-off dual-comb spectroscopy carried out with QCL frequency combs using a fast scanning technique to provide hyperspectral images with species specific absorption spectra.

Structuring at very high rates has become one of the current and important topics of interest in polymer science, because this is a common protocol in the processing of films or fibers with industrial applicability. This work presents the study by fast scanning calorimetry, FSC, of poly(vinylidene fluoride), paying special attention to the conditions for obtaining the &beta, phase of this polymer, because it is the one technologically more interesting. The results indicate that this &beta, phase of poly(vinylidene fluoride) is obtained when the sample is isothermally crystallized at temperatures below 60 &deg, C. Under non-isothermal conditions, the &beta, polymorph begins to be observed at rates above 400 &deg, C/s, although a coexistence with the &alpha, modification is observed, so that exclusively the &beta, phase is obtained only at rates higher than 3000 &deg, C/s.

In this invited paper, a series of near-field-focused (NFF) antenna arrays are introduced. Several different generating and steering methods of the NFF beam are presented. These NFF arrays with the 1-D/2-D/3-D steering performance have good prospects in the near-field (NF) fast scanning applications, e.g., electromagnetic imaging/nondestructive testing systems.

Hyperspectral imaging spectrometers are useful in numerous applications including remote sensing, environmental monitoring, surveillance, minerology and precision agriculture. Historically, high cost and complexity has limited the number of fielded hyperspectral imagers. The Computational Reconfigurable Imaging Spectrometer (CRISP) sensor is a novel hyperspectral imaging spectrometer suitable for high-resolution air or space-based missions. CRISP uses a computational imaging approach to reduce the system’s overall size and complexity. It exploits platform motion and a spectrally coded focal-plane mask to temporally modulate the optical spectrum, enabling simultaneous measurement of multiple spectral bins (i.e. multiplexing). The novel design enables high performance from smaller and less-expensive components (e.g. uncooled microbolometers), and is thus suitable for small space and air platforms. This talk discusses our demonstrator system (including recent flight results) and compares it to theory. Our flights demonstrate plume detection using an uncooled, airborne, longwave infrared CRISP imaging spectrometer. We discuss progress developing algorithms to enable spectral recovery in the presence of motion blur, utilizing the CRISP architecture to advantage. These algorithms enable a fast scanning mode, trading off computational complexity and reconstruction quality for fast area coverage rate.

Cell type classification and isolation according to imaging and spatial characteristics, beyond traditional fluorescently labeled biomarkers, enable the development of new biological insight and establishment of connections between phenotypical, morphological, and genomic cell information in normal and diseased states. Here we demonstrate a 2D image-guided cell sorter and a 3D imaging flow cytometer using fast scanning laser excitation sources. Both systems feature a cameraless design, which reconstructs cell images from the temporal readout of photomultiplier tubes.

Lidar optical architectures employing Digital Micromirror Devices provide unique features such as low mechanical inertia, a large aperture area, fast scanning speed, and a high efficiency in beam steering.