Journal articles on the topic 'Full tip imaging in APT'
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Du, Sichao, Timothy Burgess, Shyeh Tjing Loi, Baptiste Gault, Qiang Gao, Peite Bao, Li Li, et al. "Full tip imaging in atom probe tomography." Ultramicroscopy 124 (January 2013): 96–101. http://dx.doi.org/10.1016/j.ultramic.2012.08.014.
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Barroo, Cédric, Austin J. Akey, and David C. Bell. "Atom Probe Tomography for Catalysis Applications: A Review." Applied Sciences 9, no. 13 (July 5, 2019): 2721. http://dx.doi.org/10.3390/app9132721.
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Atom probe tomography is a well-established analytical instrument for imaging the 3D structure and composition of materials with high mass resolution, sub-nanometer spatial resolution and ppm elemental sensitivity. Thanks to recent hardware developments in Atom Probe Tomography (APT), combined with progress on site-specific focused ion beam (FIB)-based sample preparation methods and improved data treatment software, complex materials can now be routinely investigated. From model samples to complex, usable porous structures, there is currently a growing interest in the analysis of catalytic materials. APT is able to probe the end state of atomic-scale processes, providing information needed to improve the synthesis of catalysts and to unravel structure/composition/reactivity relationships. This review focuses on the study of catalytic materials with increasing complexity (tip-sample, unsupported and supported nanoparticles, powders, self-supported catalysts and zeolites), as well as sample preparation methods developed to obtain suitable specimens for APT experiments.
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Rice, Katherine P., Yimeng Chen, Ty J. Prosa, and David J. Larson. "Implementing Transmission Electron Backscatter Diffraction for Atom Probe Tomography." Microscopy and Microanalysis 22, no. 3 (June 2016): 583–88. http://dx.doi.org/10.1017/s1431927616011296.
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AbstractThere are advantages to performing transmission electron backscattering diffraction (tEBSD) in conjunction with focused ion beam-based specimen preparation for atom probe tomography (APT). Although tEBSD allows users to identify the position and character of grain boundaries, which can then be combined with APT to provide full chemical and orientation characterization of grain boundaries, tEBSD can also provide imaging information that improves the APT specimen preparation process by insuring proper placement of the targeted grain boundary within an APT specimen. In this report we discuss sample tilt angles, ion beam milling energies, and other considerations to optimize Kikuchi diffraction pattern quality for the APT specimen geometry. Coordinated specimen preparation and analysis of a grain boundary in a Ni-based Inconel 600 alloy is used to illustrate the approach revealing a 50° misorientation and trace element segregation to the grain boundary.
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Stadler, Johannes, Thomas Schmid, Lothar Opilik, Phillip Kuhn, Petra S. Dittrich, and Renato Zenobi. "Tip-enhanced Raman spectroscopic imaging of patterned thiol monolayers." Beilstein Journal of Nanotechnology 2 (August 30, 2011): 509–15. http://dx.doi.org/10.3762/bjnano.2.55.
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Full spectroscopic imaging by means of tip-enhanced Raman spectroscopy (TERS) was used to measure the distribution of two isomeric thiols (2-mercaptopyridine (2-PySH) and 4-mercaptopyridine (4-PySH)) in a self-assembled monolayer (SAM) on a gold surface. From a patterned sample created by microcontact printing, an image with full spectral information in every pixel was acquired. The spectroscopic data is in good agreement with the expected molecular distribution on the sample surface due to the microcontact printing process. Using specific marker bands at 1000 cm−1 for 2-PySH and 1100 cm−1 for 4-PySH, both isomers could be localized on the surface and semi-quantitative information was deduced from the band intensities. Even though nanometer size resolution information was not required, the large signal enhancement of TERS was employed here to detect a monolayer coverage of weakly scattering analytes that were not detectable with normal Raman spectroscopy, emphasizing the usefulness of TERS.
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Neyaz, Zafar. "Soft-Tip Stylet and Saline Instillation Technique: Making Difficult Percutaneous CT-Guided Biopsies Possible." Indian Journal of Radiology and Imaging 31, no. 04 (October 2021): 956–60. http://dx.doi.org/10.1055/s-0041-1741094.
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AbstractFinding a safe needle path during percutaneous computed tomography-guided biopsy is sometimes difficult due to concern for injuring a vital structure. Saline instillation technique has been used to displace the structure out of the way. Another useful tool is a soft-tip stylet. A soft-tip also referred as blunt-tip stylet for the introducer cannula is provided with some coaxial biopsy sets in additional to standard sharp-tip stylet. While the sharp-tip stylet is fitted with introducer cannula for piercing skin, muscle, and fascia, a soft-tip stylet may be used for avoiding injury to structures like vessels and bowel loops especially while advancing introducer cannula through fatty tissue. Additionally, it is also useful for avoiding injury to nerves and giving pleural anesthesia. Although its use has been described in medical literature, many radiologists are still not utilizing this tool to its full potential. In this educational exhibit, various applications of soft-tip stylet and saline instillation technique have been depicted using representative cases.
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Raffel, Markus, James T. Heineck, Edward Schairer, Friedrich Leopold, and Kolja Kindler. "Background-Oriented Schlieren Imaging for Full-Scale and In-Flight Testing." Journal of the American Helicopter Society 59, no. 1 (January 1, 2014): 1–9. http://dx.doi.org/10.4050/jahs.59.012002.
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Background-oriented schlieren (BOS) methods suited for large-scale and in-flight testing are presented with special emphasis on the detection and tracing of blade tip vortices in situ. Retroreflective recording and photogrammetric epipolar analysis for the computation of the vortices' spatial coordinates in the wind tunnel are described. Feasibility and fidelity of reference-free BOS in conjunction with natural formation backgrounds and related evaluation methods are discussed, additionally, illustrating their simplicity and robustness. Results of successful image acquisition from a chaser aircraft are presented allowing vortex wakes to be identified at a wide range of flight attitudes, including complex maneuvers.
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Fleischer, Monika. "Near-field scanning optical microscopy nanoprobes." Nanotechnology Reviews 1, no. 4 (August 1, 2012): 313–38. http://dx.doi.org/10.1515/ntrev-2012-0027.
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AbstractNear-field scanning optical microscopy (NSOM) is a powerful method for the optical imaging of surfaces with a resolution down to the nanometer scale. By focusing an external electromagnetic field to the subwavelength aperture or apex of a sharp tip, the diffraction limit is avoided and a near-field spot with a size on the order of the aperture or tip diameter can be created. This point light source is used for scanning a sample surface and recording the signal emitted from the small surface area that interacts with the near field of the probe. In tip-enhanced Raman spectroscopy, such a tip configuration can be used as well to record a full spectrum at each image point, from which chemically specific spectral images of the surface can be extracted. In either case, the contrast and resolution of the images depend critically on the properties of the NSOM probe used in the experiment. In this review, an overview of eligible tip properties and different approaches for tailoring specifically engineered NSOM probes is given from a fabrication point of view.
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Lübbe, Jannis, Matthias Temmen, Philipp Rahe, and Michael Reichling. "Noise in NC-AFM measurements with significant tip–sample interaction." Beilstein Journal of Nanotechnology 7 (December 1, 2016): 1885–904. http://dx.doi.org/10.3762/bjnano.7.181.
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The frequency shift noise in non-contact atomic force microscopy (NC-AFM) imaging and spectroscopy consists of thermal noise and detection system noise with an additional contribution from amplitude noise if there are significant tip–sample interactions. The total noise power spectral density D Δ f (f m) is, however, not just the sum of these noise contributions. Instead its magnitude and spectral characteristics are determined by the strongly non-linear tip–sample interaction, by the coupling between the amplitude and tip–sample distance control loops of the NC-AFM system as well as by the characteristics of the phase locked loop (PLL) detector used for frequency demodulation. Here, we measure D Δ f (f m) for various NC-AFM parameter settings representing realistic measurement conditions and compare experimental data to simulations based on a model of the NC-AFM system that includes the tip–sample interaction. The good agreement between predicted and measured noise spectra confirms that the model covers the relevant noise contributions and interactions. Results yield a general understanding of noise generation and propagation in the NC-AFM and provide a quantitative prediction of noise for given experimental parameters. We derive strategies for noise-optimised imaging and spectroscopy and outline a full optimisation procedure for the instrumentation and control loops.
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Paulite, Melissa, Carolin Blum, Thomas Schmid, Lothar Opilik, Klaus Eyer, Gilbert C. Walker, and Renato Zenobi. "Full Spectroscopic Tip-Enhanced Raman Imaging of Single Nanotapes Formed from β-Amyloid(1–40) Peptide Fragments." ACS Nano 7, no. 2 (January 22, 2013): 911–20. http://dx.doi.org/10.1021/nn305677k.
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Murray, Kermit K., Suman Ghorai, and Chinthaka A. Seneviratne. "Tip Enhanced Laser Ablation Sample Transfer for Mass Spectrometry." MRS Proceedings 1754 (2015): 87–95. http://dx.doi.org/10.1557/opl.2015.286.
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ABSTRACTMass spectrometry is one of the primary analysis techniques for biological analysis but there are technological barriers in sampling scale that must be overcome for it to be used to its full potential on the size scale of single cells. Current mass spectrometry imaging methods are limited in spatial resolution when analyzing large biomolecules. The goal of this project is to use atomic force microscope (AFM) tip enhanced laser ablation to remove material from cells and tissue and capture it for subsequent mass spectrometry analysis. The laser ablation sample transfer system uses an AFM stage to hold the metal-coated tip at a distance of approximately 10 nm from a sample surface. The metal tip acts as an antenna for the electromagnetic radiation and enables the ablation of the sample with a spot size much smaller than a laser focused with a conventional lens system. A pulsed nanosecond UV or visible wavelength laser is focused onto the gold-coated silicon tip at an angle nearly parallel with the surface, which results in the removal of material from a spot between 500 nm and 1 µm in diameter and 200 and 500 nm deep. This corresponds to a few picograms of ablated material, which can be captured on a metal surface for MALDI analysis. We have used this approach to transfer small peptides and proteins from a thin film for analysis by mass spectrometry as a first step toward high spatial resolution imaging.
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BRAUN, K. F., F. MORESCO, K. MORGENSTERN, S. FÖLSCH, J. REPP, S. W. HLA, G. MEYER, and K. H. RIEDER. "MANIPULATION OF ATOMS AND MOLECULES FOR CONSTRUCTION OF NANOSYSTEMS: THE SCANNING TUNNELING MICROSCOPE AS AN OPERATIVE TOOL." International Journal of Nanoscience 02, no. 04n05 (August 2003): 197–218. http://dx.doi.org/10.1142/s0219581x03001218.
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Controlled manipulations with scanning tunneling microscope (STM) down to the scale of small molecules and single atoms allow to build molecular and atomic nanosystems, leading to the fascinating possibility of creating manmade structures on atomic scale. Here we present a short review on investigations based on atomic scale manipulation. Upon soft lateral manipulation of adsorbed species, in which only tip/particle forces are used, three different manipulation modes can be discerned: pushing, pulling and sliding. Even the manipulation of strongly bound native substrate atoms is possible. We demonstrate applications as local analytic and synthetic chemistry tools, with important consequences on surface structure research. Vertical manipulation of Xe and CO leads to improved imaging with functionalized tips. With CO deliberately transferred to the tip, we have also succeeded to perform vibrational spectroscopy on single molecules. Furthermore, we describe how we have reproduced a full chemical reaction with single molecules, whereby all basic steps, namely preparation of the reactants, diffusion and association, are induced with the STM tip. Here also field and electron current effects are employed. Finally, we have extended the manipulation techniques to large specially designed molecules by performing lateral manipulation in constant height and realizing the principle of a conformational molecular switch. Artificial nanoscale structures built in atom by atom fashion can serve as quantum laboratories for investigations of various physical properties.
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Tanaka, Keisuke, Takahisa Shobu, and Hiroshi Kimachi. "Hybrid Measurement of CT and Strain Distribution of Internal Crack Using Synchrotron High-Energy Monochromatic X-Rays." Materials Science Forum 652 (May 2010): 202–9. http://dx.doi.org/10.4028/www.scientific.net/msf.652.202.
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Using high-energy monochromatic X-rays of energy 66.4keV from the synchrotron radiation source, SPring-8, we have developed a system to perform a hybrid measurement of imaging of cracks and strain distribution around cracks. This system was applied to a fatigue crack made in a round bar made of carbon steel with a diameter of 4 mm. Computed tomography of the specimen gave the three-dimensional shape of a thumb-nail crack. High tensile strain ahead of the crack was measured at the applied maximum stress, while the strain on the crack face was low because of stress relief due to crack opening. The full width at half maximum (FWHM) increased near the crack tip under loading, and then decreased after unloading. The recoverable part of FWHM by unloading was caused by the steep distribution of the applied stress in the vicinity of the crack tip. The FWHM increased by plastic deformation does not change when unloaded. The measured distributions of the lattice strain and FWHM agreed well with those of the elastic and plastic strains calculated by the finite element method, respectively.
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Lee, Ho Won, Chenyu Wang, Tae Soo Bae, Ik Yang, Yuxuan Liu, Chang Won Park, and Hyong Nyun Kim. "Tendon Regeneration After Partial-Thickness Peroneus Longus Tendon Harvesting: Magnetic Resonance Imaging Evaluation and In Vivo Animal Study." American Journal of Sports Medicine 48, no. 10 (July 6, 2020): 2499–509. http://dx.doi.org/10.1177/0363546520933628.
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Background: In recent years, the use of the anterior half of the peroneus longus tendon (AHPLT) as an autograft source for ligament reconstruction has gained popularity. However, no reports are available regarding tendon regeneration after harvesting of the AHPLT. Hypothesis: When half of the tendon is preserved during tendon harvesting, the quality of the regenerated tendon is better than that of the regenerated tendon after full-thickness harvesting. Study Design: Case series; Level of evidence, 4; controlled laboratory study. Methods: A total of 21 patients who underwent AHPLT harvesting for lower extremity ligament reconstruction participated in the magnetic resonance imaging (MRI) study to evaluate tendon regeneration 1 year after the harvesting. An in vivo animal study was performed to compare the quality of the regenerated tendon after partial-thickness and full-thickness tendon harvesting. A total of 30 adult female Sprague-Dawley rats were allocated to 2 groups—15 rats underwent partial-thickness Achilles tendon harvesting (partial-thickness harvesting [PTH] group), and 15 rats underwent full-thickness Achilles tendon harvesting (full-thickness harvesting [FTH] group). The quality of the regenerated tendons was compared 180 days after tendon harvesting. Results: All 21 patients showed regeneration of the peroneus longus tendon (PLT) (homogeneously dark on both T1- and T2-weighted sequences). The cross-sectional area of the regenerated tendon divided by that of the preoperative tendon was 92.6% and 84.5% at 4 cm and 9 cm proximal to the tip of the distal fibula, respectively. In the animal study, the mean histologic score was better for the PTH group compared with the FTH group (9.17 ± 1.35 vs 14.72 ± 0.74; P < .001). The ultimate strength and the stiffness of the regenerated Achilles tendon were significantly higher for the PTH group compared with the FTH group (35.5 ± 8.3 vs 22.4 ± 8.3 N, P = .004; and 31.6 ± 7.7 vs 23.5 ± 4.8 N/mm, P = .016). Conclusion: The PLT was found to regenerate after partial-thickness harvesting on MRI. In the animal study, the quality of the regenerated tendon when half of the tendon was preserved during tendon harvesting was better than that after full-thickness tendon harvesting.
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Akman, O., and D. Duerksen. "A68 DISTAL MIGRATION OF A PERCUTANEOUS GASTROJEJUNAL DUODOPA INFUSION TUBE DUE TO BEZOAR FORMATION AT THE JEJUNAL TUBE TIP." Journal of the Canadian Association of Gastroenterology 4, Supplement_1 (March 1, 2021): 30–31. http://dx.doi.org/10.1093/jcag/gwab002.066.
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Abstract Background Continuous intestinal infusion of levodopa/carbidopa intestinal gel (LCIG) for the treatment of advanced Parkinson’s Disease (PD) leads to less variability in plasma drug levels and improved symptom control. Percutaneous Gastrojejunostomy (PEG-J) tube placement has a high placement success rate; however, delayed tube malfunctions occur in approximately 58% of cases within two years. A rare complication is bezoar formation at the jejunal tube tip. Aims To present a case of bezoar formation at the jejunal tip of a PEG-J tube that caused distal migration of the tube with gastroduodenal ulceration and required surgical extraction. Methods Full chart review was conducted including clinical notes, laboratory results, radiographic imaging, endoscopy reports, and surgical reports. A relevant literature review was conducted. Results A 57-year-old male with severe PD underwent endoscopic guided PEG-J tube insertion for continuous infusion of LCIG; intestinal administration was effective for symptom control. Two years later, he noted that the gastric tube had retracted approximately 15 cm into the stoma without external manipulation of the apparatus. Attempts to externally pull the tube back into position were unsuccessful. The patient underwent Gastroscopy (EGD) with fluoroscopy. Contrast was used to confirm placement of the jejunal tip within the jejunum, but also showed migration of the gastric tip into the duodenum. A gastroscope was used to reposition the gastric tube in the stomach; the jejunal tube was visualized to be under traction. The bumper on the apparatus was re-positioned and external tape was used to further secure the apparatus and prevent migration. A month later the tube had migrated again; repeat EGD showed the jejunal tube to be under traction with some resultant ulceration of the pyloric channel and duodenal bulb where the tube had been pressing against the mucosa. The jejunal tube could not be pulled back and appeared to be fixed distally. A CT scan was obtained to assess for complications and a coiled tip was seen in the proximal jejunum. Surgical extraction of the malfunctioning tube was required. At laparotomy, the coiled tip of the feeding tube was successfully removed via enterotomy. The tube tip had coiled around itself and was encased with food materials, creating a large bezoar that was being pulled distally by peristalsis. The patient subsequently underwent insertion of a new GJ tube for ongoing administration of LCIG and has been doing well since. Conclusions Bezoar formation at the jejunal tip of LCIG PEG-J tubes is a rare complication and can lead to distal migration and traction related gastroduodenal ulceration. Surgical removal may be required. Funding Agencies None
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Li, Shaobo, Shuming Yang, Fei Wang, Qiang Liu, Biyao Cheng, and Yossi Rosenwaks. "Plasmonic interference modulation for broadband nanofocusing." Nanophotonics 10, no. 16 (October 26, 2021): 4113–23. http://dx.doi.org/10.1515/nanoph-2021-0405.
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Abstract Metallic plasmonic probes have been successfully applied in near-field imaging, nanolithography, and Raman enhanced spectroscopy because of their ability to squeeze light into nanoscale and provide significant electric field enhancement. Most of these probes rely on nanometric alignment of incident beam and resonant structures with limited spectral bandwidth. This paper proposes and experimentally demonstrates an asymmetric fiber tip for broadband interference nanofocusing within its full optical wavelengths (500–800 nm) at the nanotip with 10 nm apex. The asymmetric geometry consisting of two semicircular slits rotates plasmonic polarization and converts the linearly polarized plasmonic mode to the radially polarized plasmonic mode when the linearly polarized beam couples to the optical fiber. The three-dimensional plasmonic modulation induces circumference interference and nanofocus of surface plasmons, which is significantly different from the nanofocusing through plasmon propagation and plasmon evolution. The plasmonic interference modulation provides fundamental insights into the plasmon engineering and has important applications in plasmon nanophotonic technologies.
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Amyot, Romain, Arin Marchesi, Clemens M. Franz, Ignacio Casuso, and Holger Flechsig. "Simulation atomic force microscopy for atomic reconstruction of biomolecular structures from resolution-limited experimental images." PLOS Computational Biology 18, no. 3 (March 16, 2022): e1009970. http://dx.doi.org/10.1371/journal.pcbi.1009970.
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Atomic force microscopy (AFM) can visualize the dynamics of single biomolecules under near-physiological conditions. However, the scanning tip probes only the molecular surface with limited resolution, missing details required to fully deduce functional mechanisms from imaging alone. To overcome such drawbacks, we developed a computational framework to reconstruct 3D atomistic structures from AFM surface scans, employing simulation AFM and automatized fitting to experimental images. We provide applications to AFM images ranging from single molecular machines, protein filaments, to large-scale assemblies of 2D protein lattices, and demonstrate how the obtained full atomistic information advances the molecular understanding beyond the original topographic AFM image. We show that simulation AFM further allows for quantitative molecular feature assignment within measured AFM topographies. Implementation of the developed methods into the versatile interactive interface of the BioAFMviewer software, freely available at www.bioafmviewer.com, presents the opportunity for the broad Bio-AFM community to employ the enormous amount of existing structural and modeling data to facilitate the interpretation of resolution-limited AFM images.
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Gray, Mingyang L., Catharine Kappauf, and Satish Govindaraj. "Management of an Unusual Intranasal Foreign Body Abutting the Cribriform Plate: A Case Report and Review of Literature." Clinical Medicine Insights: Ear, Nose and Throat 12 (January 2019): 117955061985860. http://dx.doi.org/10.1177/1179550619858606.
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A 35-year-old man with history of schizophrenia presented 3 weeks after placing a screw in his right nostril. Initial imaging showed a screw in the right ethmoid sinus with the tip penetrating the right cribriform plate. On exam, the patient was hemodynamically stable with purulent drainage in the right nasal cavity but no visible foreign body. While most nasal foreign bodies occur in children and are generally removed at the bedside, intranasal foreign bodies in adults tend to require further assessment. The foreign body in this case was concerning for skull base involvement and the patient was brought to the operating room (OR) with neurosurgery for endoscopic sinus surgery (ESS) and removal of foreign body. The screw was removed and the patient recovered with no signs of cerebrospinal fluid (CSF) leak postoperatively. Any concern for skull base or intracranial involvement should call for a full evaluation of the mechanism of injury and intervention in a controlled environment.
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Wu, Bingzhao, Ningjie Miao, Liujun Wang, Linming Mao, and Congyou Jin. "Technology and Application of Digital Nondestructive Prescreening Based on Automated Storage." Wireless Communications and Mobile Computing 2022 (August 9, 2022): 1–9. http://dx.doi.org/10.1155/2022/9443943.
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This project around “DR digital imaging non-destructive prediction based on automatic warehousing screening technology and application” project can be divided into cable full inspection in coil based on DR digital imaging mode of the whole case study, with a small piece of material screening technology research, based on the data acquisition and recognition algorithm used for the detection of automated storage research and pilot test three corpus. The hardware framework structure and software system security access model are designed based on existing warehouse conditions. A non-destructive batch automatic pre-screening equipment is developed for small materials, which has both DR and CT functions. Cold cathode pulse ray source for needle tip pulse discharge is improved. A set of non-destructive pre-screening equipment for the whole length of the cable is developed and arranged on the warehouse automatic tray wire rack. Through the multiangle scan imaging of two ray sources, the application of image recognition is expanded, and the automatic size labeling problem warning is realized. The non-destructive pre-screening of the whole length of the cable is implemented synchronously during the process of unloading the cable from the warehouse. The insulation layer scars of the wire diameter and thickness are compared and checked, and the quality problems are visually reflected, and the detection report is automatically generated.
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Leader, Avi, Ela Giladi, Lihi Pertman, Shlomit Tamir, Avishay Elis, Pia Raanani, and Galia Spectre. "Etiology, Diagnostic Workup and Incidence of Thrombosis in Patients with Splenic Infarcts." Blood 138, Supplement 1 (November 5, 2021): 1053. http://dx.doi.org/10.1182/blood-2021-153384.
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Abstract Introduction: There are knowledge gaps regarding splenic infarcts (SI), given the heterogenic patient population and wide range of clinical presentation. Comprehensive data on the frequency, management and outcomes of cryptogenic SI are lacking. Aim: To assess the etiology, treatment patterns and outcome of patients with SI, with an emphasis on cryptogenic SI. Methods: Single-center retrospective cohort study including adults with acute symptomatic or incidental SI. Patients were indexed at SI diagnosis and records were followed for 12 months. Patients were identified by ICD-9 diagnoses and an electronic search of the text in all radiology reports, and confirmed by manual review. Thrombotic risk-factors were classified as "baseline" if known at index or as "newly-diagnosed" if identified in diagnostic tests that were performed or recommended during hospitalization for the index SI. Diagnostic work-up was performed according to the clinician's discretion. The clinical context as well as baseline and newly-diagnosed thrombotic risk factors were used to determine SI etiology at baseline. Patients with no clear SI etiology after workup were classified as cryptogenic. Imaging studies of patients with cryptogenic SI were manually reviewed by an abdominal radiologist to identify possible etiology. The study exposure was the type of antithrombotic therapy defined as the prescribed antithrombotic regimen at discharge from hospitalization for the index SI, and classified as follows: none; anticoagulation (AC) only; antiplatelet (APT) only; AC & APT. AC was defined as intermediate or full dose AC. Prophylactic dose AC was classified as no AC. The primary outcome was arterial thromboembolism (ATE; acute coronary syndrome, ischemic stroke; transient ischemic attack; systemic embolism including recurrent SI) or venous thromboembolism (VTE) during 12-month follow-up. The cumulative incidence of the primary outcome over 12 months and corresponding 95% confidence intervals (CI) was calculated for each antithrombotic therapy group and a Cox proportional hazards model was used to calculate hazard ratios (HR), with death as a competing risk. Results: The eligibility criteria were met by 255 patients. The median age was 66 years and 130 (51%) were female. At least one cardiovascular risk factor was present in 221 (87%) patients. while 44 (17%) had previously diagnosed atrial fibrillation. 30 (12%) patients had prior VTE and 83 (33%) had acute concurrent ATE or VTE diagnosed at another site during hospital admission for the index SI. The SI etiology after initial diagnostic work-up, stratified for type of antithrombotic therapy at hospital discharge, is shown in Table 1. The most prevalent presumed etiologies were active malignancy in 92 (36%), cardioembolic in 69 (27%), infection in 48 (19%), shock/hypoperfusion in 47 (18%) and abdominal surgery in 46 (18%). Myeloproliferative neoplasms (2%) and antiphospholipid syndrome (6%) were rare causes. Only 15 cases (6%) were cryptogenic. Radiology review identified a possible etiology that was missed on initial review in 5 (33%) of the 15 cryptogenic SI's. These etiologies were cardioembolic [n=3], infectious [1] and malignancy [1]. Diagnostic work-up post-SI led to identification of a previously undiagnosed thrombotic risk factor in 58 cases (23%), especially atrial fibrillation (8%) and malignancy (10%), as shown in Table 2. The yield of antiphospholipid antibody testing was 10%, after confirmatory testing (Table 2). 148 patients (58.0%) were discharged from hospital with antithrombotic therapy (Table 1). The overall 12-month cumulative incidence of ATE or VTE was 18% [95% CI 13.5-23%]. Figure 1 shows the cumulative incidence of VTE or ATE stratified for type of antithrombotic therapy. The APT only and AC & APT groups had the highest 12-month incidence of ATE/VTE (22% [11.7-34.4%] and 27.4% [14.1-42.6%], respectively). In the cryptogenic SI group, 9 (60%) received AC and 4 (27%) patients had ATE/VTE. Conclusions: SI is associated with a wide spectrum of clinical disorders. Cryptogenic SI is rare and imaging review may identify possible etiologies in such cases. Diagnostic workup leads to identification of new thrombotic risk factors in 1 in 4 patients and should be pursued. The rate of ATE or VTE at 12-months post-SI is high despite antithrombotic therapy. Further research is needed to identify the optimal antithrombotic therapy in these patients. Figure 1 Figure 1. Disclosures Leader: Leo Pharma: Honoraria; Pfizer: Consultancy, Honoraria; Novartis: Honoraria; Bayer: Honoraria; Sanofi: Honoraria.
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Toomasian, John M., and J. Patrick McCarthy. "Total extrathoracic cardiopulmonary support with kinetic assisted venous drainage: experience in 50 patients." Perfusion 13, no. 2 (March 1998): 137–43. http://dx.doi.org/10.1177/026765919801300209.
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Extrathoracic cardiopulmonary bypass is used in special situations when normal access to the right atrium and aorta is difficult or not practicable. Femero-femoral bypass using gravity drainage is effective for partial cardiopulmonary support, but cannot usually provide adequate venous drainage for full circulatory support. Kinetic assisted venous drainage (KAVD) is the process of applying a controlled suction on the venous line with a kinetic pump to augment venous drainage. KAVD has been used in 50 patients where femero-femoral bypass was selected as the mode of circulatory support. These cases included: redo-operations with significant sternal adhesions (15), minimally invasive port-access cardiac surgery (12), haemodynamic instability (10), left thoracotomy (10), and others (3). In 11 cases, a second venous catheter was added because of protocol. No appreciable increase in venous return occurred with the addition of a second drainage catheter. All patients were adequately supported and a 20-40% increase in venous return was observed once KAVD was implemented. A wide variety of different venous catheters have been used with KAVD. Optimal use relates to having a thin-walled catheter with multiple side holes, not exerting an excessive negative pressure with the pump and positioning the catheter tip at the right atrio-superior vena cava junction. Optimal catheter tip placement is enhanced by using transoesophageal echocardiography. KAVD is best regulated by measuring the siphon generated by the kinetic pump. When the inlet pressure is properly monitored and controlled, KAVD can provide adequate venous drainage to completely support the circulation on a single femoral venous cannula.
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Morshed, Ramin A., Darryl Lau, Peter P. Sun, and Lauren R. Ostling. "Spinal drop metastasis from a benign fourth ventricular choroid plexus papilloma in a pediatric patient: case report." Journal of Neurosurgery: Pediatrics 20, no. 5 (November 2017): 471–79. http://dx.doi.org/10.3171/2017.5.peds17130.
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Choroid plexus papillomas (CPPs) are typically benign tumors that can occur in any age group but are more commonly found in pediatric patients. Although these tumors are benign, there are several reports in adult patients of distant metastases present either at the time of diagnosis or occurring months to years after initial resection. Here, the authors report the case of a 14-year-old boy who presented with symptoms of elevated intracranial pressure due to obstructive hydrocephalus that was caused by a large fourth ventricular mass. Preoperative imaging included a full MRI of the spine, which revealed an intradural lesion that encased the distal sacral nerve roots at the tip of the thecal sac and was concerning for a drop metastasis. The patient underwent gross-total resection of both the fourth ventricular and sacral tumors with histology of both lesions consistent with benign CPP (WHO Grade I). In addition, the authors review prior reports of both pediatric and adult patients in whom benign CPPs have metastasized with either benign or atypical pathology found at a distant site. Taking into account this unusual case and reports in the literature, patients with even benign CPPs may warrant initial and routine follow-up imaging of the total neural axis in search of the rare, but possible, occurrence of drop metastasis.
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Barlow, Anders J., Jose F. Portoles, Naoko Sano, and Peter J. Cumpson. "Removing Beam Current Artifacts in Helium Ion Microscopy: A Comparison of Image Processing Techniques." Microscopy and Microanalysis 22, no. 5 (September 13, 2016): 939–47. http://dx.doi.org/10.1017/s1431927616011673.
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AbstractThe development of the helium ion microscope (HIM) enables the imaging of both hard, inorganic materials and soft, organic or biological materials. Advantages include outstanding topographical contrast, superior resolution down to <0.5 nm at high magnification, high depth of field, and no need for conductive coatings. The instrument relies on helium atom adsorption and ionization at a cryogenically cooled tip that is atomically sharp. Under ideal conditions this arrangement provides a beam of ions that is stable for days to weeks, with beam currents in the order of picoamperes. Over time, however, this stability is lost as gaseous contamination builds up in the source region, leading to adsorbed atoms of species other than helium, which ultimately results in beam current fluctuations. This manifests itself as horizontal stripe artifacts in HIM images. We investigate post-processing methods to remove these artifacts from HIM images, such as median filtering, Gaussian blurring, fast Fourier transforms, and principal component analysis. We arrive at a simple method for completely removing beam current fluctuation effects from HIM images while maintaining the full integrity of the information within the image.
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Yokoyama, Kunio, Masahiro Kawanishi, Makoto Yamada, Hidekazu Tanaka, Yutaka Ito, and Toshihiko Kuroiwa. "Spinal epidural hematoma following removal of incorrectly placed jugular central venous catheter." Journal of Neurosurgery: Spine 15, no. 2 (August 2011): 206–9. http://dx.doi.org/10.3171/2011.3.spine10900.
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The authors report a rare case of iatrogenic spinal epidural hematoma associated with central venous catheter cannulation via the right internal jugular vein. This 59-year-old man was operated on for stomach cancer while under general anesthesia. A central venous line was inserted via the right internal jugular vein. The operation was completed uneventfully and postoperative fluid replacement was continued without interruption. On postoperative Day 2, marked swelling around the right side of his neck gradually worsened. Cervical CT demonstrated that the catheter tip of the central venous line had penetrated the jugular vein and entered the intervertebral foramen (C5–6), thereby reaching the spinal epidural space. The patient was immediately transported to the operating room and the catheter was carefully extracted under fluoroscopy. Several minutes after catheter removal, the patient complained of sudden severe back pain and over time developed mild paraparesis of both lower extremities. Urgent MR imaging of the spine revealed a large spinal epidural hematoma extending from C-1 to T-8 that was compressing the dorsal spinal cord. The patient underwent emergency surgical removal of the epidural hematoma as well as spinal cord decompression with a T1–4 laminectomy. After surgery, the patient showed full recovery of his lower-extremity motor function.
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Madjidyar, Jawid, Lorena Pineda Vidal, Naomi Larsen, and Olav Jansen. "Influence of Thrombus Composition on Thrombectomy: ADAPT vs. Balloon Guide Catheter and Stent Retriever in a Flow Model." RöFo - Fortschritte auf dem Gebiet der Röntgenstrahlen und der bildgebenden Verfahren 192, no. 03 (September 12, 2019): 257–63. http://dx.doi.org/10.1055/a-0998-4246.
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Purpose A first-pass, direct aspiration technique and stent retrieval with a balloon guide catheter represent advanced thrombectomy techniques that are increasingly being used in the clinical routine. The purpose of this experimental study was to evaluate whether the techniques’ effectiveness depended on the clot composition and to visualize the interaction between the devices and the clot. Materials and Methods Erythrocyte-rich (red) and fibrin-rich (white) clots were placed into the M1-segment of the middle cerebral artery in a transparent vascular phantom with physiological architecture. Physiological hemodynamic conditions were maintained with a programmable pump. On the one hand direct aspiration with a 5F aspiration catheter (ADAPT) and on the other hand stent retrieval with a balloon guide catheter (flow arrest/reversal) was performed. The experiments were made under direct visual control to observe the interaction between the devices and the clot. The primary end points were the number of passes/maneuvers and the occurrence of distal emboli and emboli in a new territory (anterior cerebral artery), until full recanalization was achieved. The experiment was filmed with a full high-definition camera identifying emboli. Results Six experiments were conducted for each technique and clot model. Red clots were retrieved by ADAPT with fewer passes and distal emboli, and could usually be aspirated directly at the occlusion site. White clots clogged the tip of the 5F aspiration catheter in every experiment. The catheter had to be pulled back into the long sheath in the cervical internal carotid artery, producing distal emboli. White clots were retrieved by the stent retriever and balloon guide catheter with fewer distal emboli. There was no difference in the number of passes. The stent-thrombus interaction was superficial in both clot models. Successful retrieval was granted by the flow arrest and proximal aspiration/flow reversal. One embolus in a new territory developed when using each technique in white clots. Conclusion This experimental study showed that the efficacy of advanced thrombectomy techniques might depend on clot composition. Identifying the right technique for the right clot might improve the results of thrombectomy. In a clinical setting the thrombus morphology in non-enhanced CT could be used as a marker for patient selection. Key Points: Citation Format
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Bouaziz, Djamila, Grégoire Chabrol, Assia Guessoum, Nacer-Eddine Demagh, and Sylvain Lecler. "Photonic Jet-Shaped Optical Fiber Tips versus Lensed Fibers." Photonics 8, no. 9 (September 7, 2021): 373. http://dx.doi.org/10.3390/photonics8090373.
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Shaped optical fiber tips have recently attracted a lot of interest for photonic jet light focusing due to their easy manipulation to scan a sample. However, lensed optical fibers are not new. This study analyzes how fiber tip parameters can be used to control focusing properties. Our study shows that the configurations to generate a photonic jet (PJ) can clearly be distinguished from more classical-lensed fibers focusing. PJ is a highly concentrated, propagative light beam, with a full width at half maximum (FWHM) that can be lower than the diffraction limit. According to the simulations, the PJs are obtained when light is coupled in the guide fundamental mode and when the base diameter of the microlens is close to the core diameter. For single mode fibers or fibers with a low number of modes, long tips with a relatively sharp shape achieve PJ with smaller widths. On the contrary, when the base diameter of the microlens is larger than the fiber core, the focus point tends to move away from the external surface of the fiber and has a larger width. In other words, the optical system (fiber/microlens) behaves in this case like a classical-lensed fiber with a larger focus spot size. The results of this study can be used as guidelines for the tailored fabrication of shaped optical fiber tips according to the targeted application.
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Schonauer, Claudio, Gianpaolo Jannelli, Enrico Tessitore, Adrien Thomas May, Ramona Guatta, and Andrea Bartoli. "Endoscopic resection of a low-grade ependymoma of the pineal region." Surgical Neurology International 12 (June 14, 2021): 279. http://dx.doi.org/10.25259/sni_250_2021.
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Background: Full endoscopic resection of solid brain tumors represents a challenge for neurosurgeons. This can be achieved with modern technology and advanced surgical tools. Case Description: A 23-years-old male was referred to our unit with raised intracranial pressure. Head computed tomography and magnetic resonance imaging (MRI) revealed obstructive hydrocephalus and a third ventricle lesion. Endoscopic third ventriculostomy and biopsy were performed, a left frontal external ventricular drain was left in place. A second-look surgery for endoscopic removal was planned. Decision to proceed with an endoscopic removal was supported by the following characteristics found during the first surgery: tumor exophytic, soft texture, scarce vascularity, and low-grade appearance. A rescue strategy for microscopic resection via transcallosal approach was decided. A straight trajectory to the tumor was planned with navigation. A further anterior left frontal burr-hole was performed, and the ventricular system was entered via the left frontal horn. Resection was carried out alternating laser for hemostasis and cutting, endoscopic ultrasonic aspirator, and endoscopic forceps for piecemeal resection. Laser hemostasis and cutting (1 Watt power at tip, continuous wave mode) were useful at the ventricular wall-tumor interface. Relevant landmarks guided the approach and the resection (foramen of Monro, mammillary bodies, aqueduct, pineal and suprapineal recess, and posterior commissure). The surgery was carried uneventfully. Histopathology confirmed a lowgrade ependymoma. Post-operative MRI showed residual tumor within the lower aqueduct. At 3 years follow-up, residual tumor is stable. Conclusion: In selected cases, endoscopic resection for third ventricular tumors is feasible and safe, and represents a valid alternative to microsurgical approaches.
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Barg, Alexej, Maxwell W. Weinberg, Nathan P. Davidson, Beat Hintermann, Charles L. Saltzman, and Nicola Krähenbühl. "Is Load Application Necessary When Using CT Scans to Diagnose Syndesmotic Injuries? A Cadaver Study." Foot & Ankle Orthopaedics 4, no. 4 (October 1, 2019): 2473011419S0001. http://dx.doi.org/10.1177/2473011419s00011.
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Category: Ankle, Trauma, Imaging Introduction/Purpose: Injury to the distal tibio-fibular syndesmosis is common and appears in up to 20% of patients with an ankle sprain or ankle fracture. While pronounced injuries can be reliably diagnosed using conventional radiographs, assessment of subtle syndesmotic injuries is challenging. With the introduction of weightbearing CT (WBCT) scans, detailed assessment of foot and ankle disorders under load bearing conditions became possible. The purpose of this cadaver study was to assess the influence of weight on assessment of incomplete and more complete syndesmotic injuries using two-dimensional (2D) measurements on axial CT images. We hypothesized that weight would significantly impact assessment of both incomplete and more complete injuries to the distal tibio-fibular syndesmosis. Methods: Fourteen paired male cadavers (tibial plateau to toe-tip) were included. A radiolucent frame held specimens in a plantigrade position while both non-weightbearing and weightbearing CT scans were taken. Four conditions were tested: First, intact ankles (Native) were scanned. Second, one specimen from each pair underwent anterior inferior tibio-fibular ligament (AITFL) transection (Condition 1A), while the contralateral underwent deltoid transection (Condition 1B). Third, the remaining intact deltoid or AITFL was transected (Condition 2). Finally, the distal tibio-fibular interosseous membrane (IOM) was transected in all ankles (Condition 3). For each condition, non-weightbearing, half-bodyweight (42.5 kg), and full-bodyweight (85 kg) CT scans were taken. Six measurements were performed to assess the integrity of the distal tibio-fibular syndesmosis on axial CT scans 1 cm above the ankle joint (Figure 1A/ B) and two measurements at the level of the talar surface (Figure 1C). Inter- and intra- observer agreement were additionally calculated. Results: Inter- and intra-observer agreement differed between measurements. Excellent agreement was evident for the tibio- fibular clear space (TFCS) and tibio-fibular overlap (TFO) with an intra-observer agreement of 0.79 and 0.94, respectively. Poor agreement was evident for Angle 1 (inter-observer, 0.39). Agreement of the other measurements (inter- and intra-observer) was either rated as fair or good and ranged from 0.44 to 0.71. Weightbearing had no significant influence on measurements. Only more complete injuries (Condition 3) differed from native ankles when using either the anterior tibio-fibular distance (ATFD) or TFO. For these two measurements, no significant differences were observed within each condition between non-, half-, and full- weightbearing. Also, no significant differences were evident between single AITFL and deltoid ligament transection for the ATFD and TFO. Conclusion: Load application does not impact the ability of WBCT scans to diagnose incomplete and also more complete syndesmotic injuries in a cadaver model. The utility of current 2D measurements on axial WBCT scans for diagnosing incomplete syndesmotic injuries is questionable. Nevertheless, the ability to reliably position the foot during imaging is an advantage of WBCT technology over other imaging options. Further investigations using more precise measurement options (e.g. 3-dimensional [3D] measurements) are necessary to better understand the potential role of weight bearing to diagnose syndesmotic injuries with CT scan imaging technology.
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Jarmusch, A. K., C. T. Mahapatra, V. Pirro, C. R. Ferreira, and M. S. Sepúlveda. "59 LIPID DYNAMICS IN THE EARLY EMBRYONIC DEVELOPMENT OF ZEBRAFISH BY DESORPTION ELECTROSPRAY IONIZATION MASS SPECTROMETRY IMAGING AND NANOELECTROSPRAY–MASS SPECTROMETRY." Reproduction, Fertility and Development 28, no. 2 (2016): 159. http://dx.doi.org/10.1071/rdv28n2ab59.
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This study introduces a combination of mass spectrometry-based analytical approaches with little or no sample preparation for the study of zebrafish (Danio rerio) lipid metabolism during early development (0 through 96 h post-fertilization, hpf). Desorption electrospray ionization mass spectrometry (DESI-MS) imaging and nanoelectrospray (nESI) MS were used. Embryos (N = 107) were placed onto filter paper squares and analysed by DESI-MS imaging. Embryos were arranged in rows with each one corresponding to a different developmental time, so that each DESI-MS image contained arrays of samples at different hpf. After completion of DESI-MS acquisition, the arrays were cut into strips of paper, isolating each embryo, which was subsequently inserted into a nESI tip and analysed. All experiments were performed using a linear ion trap mass spectrometer. DESI-MS images were acquired in the positive ion mode using acetonitrile doped with 10 ppm AgNO3, which allowed for the detection of cytosolic neutral lipids, such as cholesteryl esters (CE), diacylglicerols (DAG), triacylglycerols (TAG), squalene, and ubiquinone. For the nESI, experiments were run in full mass scan and MS/MS, in both negative and positive ion mode, using a mixture of dimethylformamide and acetonitrile to detect membrane phospholipids (e.g. phosphatidylcholines and phosphatidylglycerols). Principal component analysis was used to explore DESI-MS images and nESI data in an unsupervised fashion. The combination of DESI-MS imaging, providing chemical and spatial location, and nanoESI, providing a broader and more extensive structural information, showed that the lipid content changes dramatically over the first days of development. Accumulation of DAG and TAG, which are usually concentrated in the embryos yolk sac as an important storage for early development, were observed between 0 and 48 hpf. Embryos at the intermediate phase of development (24 hpf) were distributed between those of 0 and 48 hpf, reflecting the dynamics associated with development and might be correlated with TAG consumption and de novo synthesis. After 72 and 96 hpf, samples differed from prior developmental stages by the content of squalene, ubiquinone, and CE 22 : 5 (overexpressed), while the TAG content decreased. Further decrease of TAGs and ubiquinone occurred between 72 and 96 hpf. These observations indicated that zebrafish embryos rely entirely on the yolk sac for the nutrients needed to sustain growth and survival during the first four days of development. Yolk lipids are the likely source of TAGs, as well as cholesterol, a required component of cell membranes and a precursor for bile acids. The abundance of ubiquinone can be tied to zebrafish embryo growth, differentiation and organogenesis, and activation of mitochondria.
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Mohtasib, Rafat S., Kamal Alshamiri, Aman Jobeir, Farida Mohsin Ambu-Saidi, Ahmed Masawi, Lamya Alabdulaziz, and Faisal Bin Hussain. "Sonographic measurements for spleen size in healthy Saudi children and correlation with body parameters." Annals of Saudi Medicine 41, no. 1 (January 2021): 14–23. http://dx.doi.org/10.5144/0256-4947.2021.14.
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BACKGROUND: Ultrasound is commonly the first-line imaging modality for assessing the visceral organ dimensions without any risk of radiation. An abnormal size of the spleen may indicate disease, but the evaluation is challenging because of the normal size changes with age. In addition, published normal value charts for children may vary by population and methods. OBJECTIVES: Determine normal growth curves for splenic length in relationship to sex, age, body weight, height, body mass index, and body surface area of healthy children in Saudi Arabia. DESIGN: A retrospective review of ultrasonography images SETTING: Tertiary referral hospital SUBJECTS AND METHODS: We included all normal ultrasonography exams of splenic length (from full-term neonates to 16 years of age) performed between 2003 and 2018. The greatest longitudinal distance of the spleen from the dome to the tip (splenic length) measured at the hilum in the coronal plane was obtained by ultrasonography. MAIN OUTCOME MEASURES: The relationship between the longitudinal length of the spleen and sex, age, height, weight, body mass index, and body surface area. SAMPLE SIZE: 1028 healthy children RESULTS: Height had the most significant correlation with the length of the spleen ( P <.001). There was a consistent difference in splenic length according to sex. The spleen was longer in males than in females in children older than 2 years. In terms of splenic growth according to age, our data showed a statistically significant correlation between the ages of 0-24 months and 2-16 years. There was a significant difference between cases from Saudi Arabia, the United States ( P =.023) and India ( P =.045). CONCLUSION: We developed scatter plots between splenic lengths and body parameters among Saudi children for children from 0 day to 24 months and children from 2 years to 16 years for reference. LIMITATION: Retrospective study. Ultrasound techniques in patient positioning, and cursor placement differed from other studies, which can affect measurements of splenic length. CONFLICTS OF INTEREST: None.
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Rancy, Schneider, Stephanie Malliaris, Eric Bogner, and Scott Wolfe. "Intramedullary Fixation of Distal Radius Fractures Using CAGE-DR Implant." Journal of Wrist Surgery 07, no. 05 (September 18, 2018): 358–65. http://dx.doi.org/10.1055/s-0038-1669438.
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Purpose CAGE-DR implant is a novel Food and Drug Administration approved intramedullary fracture fixation device used for distal radius fractures. We examine a series of 22 patients and report the outcomes with this device. Materials and Methods A total of 24 patients with distal radius fractures (8 articular AO type C1/C2; 16 extra-articular AO type A2/A3) underwent open reduction and internal fixation (ORIF) using CAGE-DR implant by a single surgeon. Data including fracture type, angle of displacement, radiographic consolidation, grip strength, wrist range of motion (ROM), patient-rated wrist evaluation (PRWE), and Visual Analog Scale (VAS) pain scores were recorded at time of surgery and at standard follow-up. Results All 24 patients underwent uneventful ORIF. At first follow-up visit (9 days), all patients had full digital ROM (measured as 0 cm tip-to-palm distance). Two patients were lost to follow-up. Eighteen of the remaining 22 patients had sufficient radiographic follow-up and all 18 demonstrated healing. At latest follow-up (mean 9.7 months, range, 3–20), VAS pain scores averaged 0.6 (range, 0–8) and PRWE averaged 12.1 (range, 0–53.5). Grip strength of the operated hand averaged 58 lbs (range, 20–130). ROM included: wrist flexion 73° (50–95), wrist extension 78° (60–110), pronation 77° (60–90), supination 79° (60–90), ulnar deviation 31° (5–45), and radial deviation 17° (10–30). Three patients underwent screw removal to prevent tendon irritation. One patient underwent hardware removal due to prominence on imaging but was asymptomatic. There were otherwise no major complications, including complex regional pain syndrome, in the series to date. Conclusion The CAGE-DR fracture fixation system is a promising alternative to established methods of distal radius internal fixation. This series has a low reported pain score starting immediately postoperatively and a low complication rate. This novel device is a promising option for internal fixation of displaced distal radius fractures with a low complication profile. Level of Evidence This is a level IV, therapeutic study.
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Orzechowska, Zuzanna, Mariusz Mrózek, Wojciech Gawlik, and Adam Wojciechowski. "Preparation and characterization of AFM tips with nitrogen-vacancy and nitrogen-vacancy-nitrogen color centers." Photonics Letters of Poland 13, no. 2 (June 30, 2021): 28. http://dx.doi.org/10.4302/plp.v13i2.1095.
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We demonstrate a simple dip-coating method of covering standard AFM tips with nanodiamonds containing color centers. Such coating enables convenient visualization of AFM tips above transparent samples as well as using the tip for performing spatially resolved magnetometry. Full Text: PDF ReferencesG. Binnig, C. F. Quate, C. Gerber, "Atomic Force Microscope", Phys. Rev. Lett. 56, 930 (1986). CrossRef F .J. Giessibl, "Advances in atomic force microscopy", Rev. Mod. Phys. 75, 949 (2003). CrossRef S. Kasas, G. Dietler, "Probing nanomechanical properties from biomolecules to living cells", Eur. J. Appl. Physiol. 456, 13 (2008). CrossRef C. Roduit et al., "Stiffness Tomography by Atomic Force Microscopy", Biophys. J. 97, 674 (2009). CrossRef L. A. Kolodny et al., "Spatially Correlated Fluorescence/AFM of Individual Nanosized Particles and Biomolecules", Anal. Chem. 73, 1959 (2001). CrossRef L. Rondin et al., "Magnetometry with nitrogen-vacancy defects in diamond", Rep. Prog. Phys. 77, 056503 (2014). CrossRef C. L. Degen, "Scanning magnetic field microscope with a diamond single-spin sensor", Appl. Phys. Lett. 92, 243111 (2008). CrossRef J. M. Taylor et al., "High-sensitivity diamond magnetometer with nanoscale resolution", Nat. Phys. 4, 810 (2008). CrossRef J. R. Maze et al., "Nanoscale magnetic sensing with an individual electronic spin in diamond", Nature 455, 644 (2008). CrossRef L. Rondin et al., "Nanoscale magnetic field mapping with a single spin scanning probe magnetometer", Appl. Phys. Lett. 100, 153118 (2012). CrossRef J. P. Tetienne et al., "Nanoscale imaging and control of domain-wall hopping with a nitrogen-vacancy center microscope", Science 344, 1366 (2014). CrossRef R. Nelz et al., "Color center fluorescence and spin manipulation in single crystal, pyramidal diamond tips", Appl. Phys. Lett. 109, 193105 (2016). CrossRef G. Balasubramanian et al., "Nanoscale imaging magnetometry with diamond spins under ambient conditions", Nature 455, 648 (2008). CrossRef P. Maletinsky et al., "A robust scanning diamond sensor for nanoscale imaging with single nitrogen-vacancy centres", Nat. nanotechnol. 7, 320 (2012). CrossRef L. Thiel et al., "Quantitative nanoscale vortex imaging using a cryogenic quantum magnetometer", Nat. nanotechnol. 11, 677 (2016). CrossRef F. Jelezko et al., "Single spin states in a defect center resolved by optical spectroscopy", Appl. Phys. Lett. 81, 2160 (2002). CrossRef M. W. Doherty et al., "The nitrogen-vacancy colour centre in diamond", Phys. Rep. 528, 1 (2013). CrossRef C. Kurtsiefer, S. Mayer, P. Zarda, H. Weinfurter, "Stable Solid-State Source of Single Photons", Phys. Rev. Lett. 85, 290 (2000). CrossRef A. Gruber, A. Dräbenstedt, C. Tietz, L. Fleury, J. Wrachtrup, C. Von Borczyskowski, "Scanning Confocal Optical Microscopy and Magnetic Resonance on Single Defect Centers", Science 276, 2012 (1997). CrossRef F. Dolde et al., "Electric-field sensing using single diamond spins", Nat. Phys. 7, 459 (2011). CrossRef K. Sasaki et al., "Broadband, large-area microwave antenna for optically detected magnetic resonance of nitrogen-vacancy centers in diamond", Rev. Sci. Instrum. 87, 053904 (2016). CrossRef A. M. Wojciechowski et al., "Optical Magnetometry Based on Nanodiamonds with Nitrogen-Vacancy Color Centers", Materials 12, 2951 (2019). CrossRef I. V. Fedotov et al., "Fiber-optic magnetometry with randomly oriented spins", Opt. Lett. 39, 6755 (2014). CrossRef
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Malinowski, Jakub, Ewa Niebudek-Bogusz, Marcin Just, Joanna Morawska, Anna Racino, Joanna Hoffman, Magda Barańska, Magdalena Marianna Kowalczyk, and Wioletta Pietruszewska. "Laryngeal High-Speed Videoendoscopy with Laser Illumination: A Preliminary Report." Otolaryngologia Polska 75, no. 6 (September 7, 2021): 1–10. http://dx.doi.org/10.5604/01.3001.0015.2575.
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<br><b>Introduction:</b> Advances in computer image analysis have enabled the use of new functional imaging methods in the diagnosis of laryngeal diseases. Particularly interesting techniques of dynamic laryngeal imaging involve High Speed Videoendoscopy (HSV). This still-developed technique allows to overcome the limitations of laryngovideostroboscopy (LVS) and a more detailed analysis of the glottal function based on the image of the actual vibrations of the vocal folds. It also enables the determination of objective coefficients parameterizing phonatory vibrations of the vocal folds.</br> <br><b>Aim:</b> The aim of this pilot study was to evaluate the use of a high-speed videoendoscopy set with laser illumination for the diagnosis of glottic pathology in ENT practice.</br> <br><b>Material and methods:</b> The study included 40 patients who underwent LVS followed by HSV. The modern HSV examination kit – Advanced Larynx Imager System (ALIS), used for the first time in a clinical setting in Poland, is characterized by significantly improved, compared to the previously used high-speed cameras, operational parameters – a light head, the possibility of continuous lighting operation without excessive heating of the head tip, registration of the image in full color scale. Thanks to such modernization, the safety and course of the examination do not differ from laryngoscopy conducted with commonly used recorders. The device owes some of these improvements to a laser illuminator which was used for the first time as the main light source in a high-speed camera. In the study, two cases were selected to present the results of HSV and the analysis of the generated kymograms – a woman with no glottic pathology and a man with a polyp of the right vocal fold. In the first case, the HSV examination compared with the LVS revealed a discrete glottis functional disorder in the form of a tendency to hyperphonation. The patient with an organic lesion had a clearly visible irregularity of vocal fold vibrations, which also allowed to trace mucosal wave disturbances related to its reflection from the pathological structure of the glottis and the formation of a return wave, both on the fold affected by the lesion and, to a lesser extent, contralaterally. The glottic dysfunctions observed in the studied patients were confirmed in the generated kymograms and the graphs of the glottal width waveform (GWW), as well as in the parameters calculated on their basis, assessing the frequency and amplitude of phonatory vibrations.</br> <br><b>Conclusions:</b> The use of high-speed videoendoscopy allows for a much more accurate assessment of the phonatory function of the glottis than in laryngovideostroboscopy. The presented HSV system allows for obtaining high quality kinematic images of the larynx, color fidelity, and contrast. The use of this technology in laryngological practice enables precise structural and functional assessment of the glottis and detection of discrete phonation disorders that elude the techniques used so far.</br>
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Fougerouse, Denis, David W. Saxey, William D. A. Rickard, Steven M. Reddy, and Rick Verberne. "Standardizing Spatial Reconstruction Parameters for the Atom Probe Analysis of Common Minerals." Microscopy and Microanalysis, December 1, 2021, 1–10. http://dx.doi.org/10.1017/s1431927621013714.
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Abstract Well-defined reconstruction parameters are essential to quantify the size, shape, and distribution of nanoscale features in atom probe tomography (APT) datasets. However, the reconstruction parameters of many minerals are difficult to estimate because intrinsic spatial markers, such as crystallographic planes, are not usually present within the datasets themselves. Using transmission and/or scanning electron microscopy imaging of needle-shaped specimens before and after atom probe analysis, we test various approaches to provide best-fit reconstruction parameters for voltage-based APT reconstructions. The results demonstrate that the length measurement of evaporated material, constrained by overlaying pre- and post-analysis images, yields more consistent reconstruction parameters than the measurement of final tip radius. Using this approach, we provide standardized parameters that may be used in APT reconstructions of 11 minerals. The adoption of standardized reconstruction parameters by the geoscience APT community will alleviate potential problems in the measurement of nanoscale features (e.g., clusters and interfaces) caused by the use of inappropriate parameters.
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Ren, Yanru, Hélène Autefage, Julian R. Jones, Molly M. Stevens, Paul A. J. Bagot, and Michael P. Moody. "Developing Atom Probe Tomography to Characterize Sr-Loaded Bioactive Glass for Bone Scaffolding." Microscopy and Microanalysis, October 25, 2021, 1–11. http://dx.doi.org/10.1017/s1431927621012976.
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In this study, atom probe tomography (APT) was used to investigate strontium-containing bioactive glass particles (BG-Sr10) and strontium-releasing bioactive glass-based scaffolds (pSrBG), both of which are attractive biomaterials with applications in critical bone damage repair. We outline the challenges and corresponding countermeasures of this nonconductive biomaterial for APT sample preparation and experiments, such as avoiding direct contact between focussed ion beam micromanipulators and the extracted cantilever to reduce damage during liftout. Using a low imaging voltage (≤3 kV) and current (≤500 pA) in the scanning electron microscope and a low acceleration voltage (≤2 kV) and current (≤200 pA) in the focussed ion beam prevents tip bending in the final stages of annular milling. To optimize the atom probe experiment, we considered five factors: total detected hits, multiple hits, the background level, the charge-state ratio, and the accuracy of the measured compositions, to explore the optimal laser pulse for BG-Sr10 bioactive glass. We show that a stage temperature of 30 K, 200–250 pJ laser pulse energy, 0.3% detection rate, and 200 kHz pulse rate are optimized experimental parameters for bioactive glass. The use of improved experimental preparation methods and optimized parameters resulted in a 90% successful yield of pSrBG samples by APT.
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Chien, Alexander, Sheng Min Shih, Raqual Bower, Douglas Tritschler, Mary E. Porter, and Ahmet Yildiz. "Dynamics of the IFT machinery at the ciliary tip." eLife 6 (September 20, 2017). http://dx.doi.org/10.7554/elife.28606.
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Intraflagellar transport (IFT) is essential for the elongation and maintenance of eukaryotic cilia and flagella. Due to the traffic jam of multiple trains at the ciliary tip, how IFT trains are remodeled in these turnaround zones cannot be determined by conventional imaging. Using PhotoGate, we visualized the full range of movement of single IFT trains and motors in Chlamydomonas flagella. Anterograde trains split apart and IFT complexes mix with each other at the tip to assemble retrograde trains. Dynein-1b is carried to the tip by kinesin-II as inactive cargo on anterograde trains. Unlike dynein-1b, kinesin-II detaches from IFT trains at the tip and diffuses in flagella. As the flagellum grows longer, diffusion delays return of kinesin-II to the basal body, depleting kinesin-II available for anterograde transport. Our results suggest that dissociation of kinesin-II from IFT trains serves as a negative feedback mechanism that facilitates flagellar length control in Chlamydomonas.
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Fach, Christian, Nico Rödel, Jürgen Schorr, Christian Krüger, Andreas Dreizler, and Benjamin Böhm. "Multi-parameter imaging of in-cylinder processes during transient engine operation for the investigation of soot formation." International Journal of Engine Research, May 25, 2021, 146808742110199. http://dx.doi.org/10.1177/14680874211019976.
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Transient engine operation of direct-injection spark ignition engines can result in high particulate number emissions. To investigate the causes of soot formation, an engine test rig was developed to perform detailed measurements of real transient operation. For this purpose, a single-cylinder full-metal engine with a real combustion chamber geometry was equipped with minimally invasive optical accesses. Simultaneous high-speed endoscopic PIV, spray visualization, and combustion imaging were applied to investigate the in-cylinder processes in detail. Endoscopic PIV was first compared in the central symmetry plane with classical PIV performed at the equivalent optical engine at steady-state operation for verification. Then the engine parameters of a tip-in performed by the corresponding four-cylinder engine, which led to high particle number emissions, were applied to the single-cylinder engine. The engine parameters were in a good agreement and particle number emissions due to the maneuver were within the same range of several 106 #/cm3. In total, 19 repetitions of the tip-in maneuver were analyzed with respect to the in-cylinder processes and repeatability of engine parameters. Furthermore, the in-cylinder flow field during the late compression stroke, flame propagation, and soot luminosity of single cycles during the tip-in indicated cause-and-effect chains for the formation of pool fire and soot at the injector tip. The direction of the flow below the spark plug influenced the direction of flame propagation. An early arrival of the flame enhanced the formation of soot from fuel films formed on the piston surface or at the injector. In engine applications, counter measures can be applied to reduce the particle number emissions when accounting for these indicated cause-and-effect chains.
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Eichhorn, Anna L., and Christian Dietz. "Torsional and lateral eigenmode oscillations for atomic resolution imaging of HOPG in air under ambient conditions." Scientific Reports 12, no. 1 (May 28, 2022). http://dx.doi.org/10.1038/s41598-022-13065-9.
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AbstractCombined in-plane and out-of-plane multifrequency atomic force microscopy techniques have been demonstrated to be important tools to decipher spatial differences of sample surfaces at the atomic scale. The analysis of physical properties perpendicular to the sample surface is routinely achieved from flexural cantilever oscillations, whereas the interpretation of in-plane sample properties via force microscopy is still challenging. Besides the torsional oscillation, there is the additional option to exploit the lateral oscillation of the cantilever for in-plane surface analysis. In this study, we used different multifrequency force microscopy approaches to attain better understanding of the interactions between a super-sharp tip and an HOPG surface focusing on the discrimination between friction and shear forces. We found that the lateral eigenmode is suitable for the determination of the shear modulus whereas the torsional eigenmode provides information on local friction forces between tip and sample. Based on the results, we propose that the full set of elastic constants of graphite can be determined from combined in-plane and out-of-plane multifrequency atomic force microscopy if ultrasmall amplitudes and high force constants are used.
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Jong Yoon, W., Carlos A. Velasquez, Lee W. White, Blake Hannaford, Yoon Sang Kim, and Thomas S. Lendvay. "Preliminary Articulable Probe Designs With RAVEN and Challenges: Image-Guided Robotic Surgery Multitool System." Journal of Medical Devices 8, no. 1 (December 6, 2013). http://dx.doi.org/10.1115/1.4025908.
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The primary focus of the vision systems in current minimally invasive surgery (MIS) surgical systems has been on the improvement of immersive experience through a static approach. One of the current limitations in an MIS robotic surgery is the limited field of view and restricted perspective due to the use of a sole rigid 3D endoscope. We seek to integrate a modular articulable imaging device and the teleoperated surgical robot, RAVEN. Another additional flexible imager can be helpful in viewing occluded surgical targets, giving increased visualization options. Two probe designs are proposed and tested to evaluate a robotized steering mechanism within the MIS robot framework. Both designs, a separate flexible imager and a fixed camera on a tool tip, did not show much improvement in reducing task completion time. The new system may have some potential in improved precise manipulation of surgical tools, which may offer safety benefits once the surgeon is trained. We have demonstrated feasibility of a novel MIS instrument imaging device to aid in viewing potentially occluded surgical targets. A new concept, a modular axis-shared articulable imaging probe located at the vicinity of a tool tip, is proposed for future evaluation. Full integration of the new flexible imaging device into the grasper of the RAVEN surgical robot is under study coordinated with clinicians.
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Bird, Alix, Lauren Oakden-Rayner, Christopher McMaster, Luke A. Smith, Minyan Zeng, Mihir D. Wechalekar, Shonket Ray, Susanna Proudman, and Lyle J. Palmer. "Artificial intelligence and the future of radiographic scoring in rheumatoid arthritis: a viewpoint." Arthritis Research & Therapy 24, no. 1 (December 12, 2022). http://dx.doi.org/10.1186/s13075-022-02972-x.
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AbstractRheumatoid arthritis is an autoimmune condition that predominantly affects the synovial joints, causing joint destruction, pain, and disability. Historically, the standard for measuring the long-term efficacy of disease-modifying antirheumatic drugs has been the assessment of plain radiographs with scoring techniques that quantify joint damage. However, with significant improvements in therapy, current radiographic scoring systems may no longer be fit for purpose for the milder spectrum of disease seen today. We argue that artificial intelligence is an apt solution to further improve upon radiographic scoring, as it can readily learn to recognize subtle patterns in imaging data to not only improve efficiency, but can also increase the sensitivity to variation in mild disease. Current work in the area demonstrates the feasibility of automating scoring but is yet to take full advantage of the strengths of artificial intelligence. By fully leveraging the power of artificial intelligence, faster and more sensitive scoring could enable the ongoing development of effective treatments for patients with rheumatoid arthritis.
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Badt, Noam, and Ori Katz. "Real-time holographic lensless micro-endoscopy through flexible fibers via fiber bundle distal holography." Nature Communications 13, no. 1 (October 13, 2022). http://dx.doi.org/10.1038/s41467-022-33462-y.
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AbstractFiber-based micro-endoscopes are a critically important tool for minimally-invasive deep-tissue imaging. However, current micro-endoscopes cannot perform three-dimensional imaging through dynamically-bent fibers without the use of bulky optical elements such as lenses and scanners at the distal end, increasing the footprint and tissue-damage. Great efforts have been invested in developing approaches that avoid distal bulky optical elements. However, the fundamental barrier of dynamic optical wavefront-distortions in propagation through flexible fibers limits current approaches to nearly-static or non-flexible fibers. Here, we present an approach that allows holographic, bend-insensitive, coherence-gated, micro-endoscopic imaging using commercially available multi-core fibers (MCFs). We achieve this by adding a partially-reflecting mirror to the distal fiber-tip, allowing to perform low-coherence full-field phase-shifting holography. We demonstrate widefield diffraction-limited reflection imaging of amplitude and phase targets through dynamically bent fibers at video-rate. Our approach holds potential for label-free investigations of dynamic samples.
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Anand, Gagandeep S., Janice C. Lee, Schuyler D. Van Dyk, Adam K. Leroy, Erik Rosolowsky, Eva Schinnerer, Kirsten Larson, et al. "Distances to PHANGS Galaxies: New Tip of the Red Giant Branch Measurements and Adopted Distances." Monthly Notices of the Royal Astronomical Society, November 25, 2020. http://dx.doi.org/10.1093/mnras/staa3668.
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Abstract PHANGS-HST is an ultraviolet-optical imaging survey of 38 spiral galaxies within ∼20 Mpc. Combined with the PHANGS-ALMA, PHANGS-MUSE surveys and other multiwavelength data, the dataset will provide an unprecedented look into the connections between young stars, H ii regions, and cold molecular gas in these nearby star-forming galaxies. Accurate distances are needed to transform measured observables into physical parameters (e.g., brightness to luminosity, angular to physical sizes of molecular clouds, star clusters and associations). PHANGS-HST has obtained parallel ACS imaging of the galaxy halos in the F606W and F814W bands. Where possible, we use these parallel fields to derive tip of the red giant branch (TRGB) distances to these galaxies. In this paper, we present TRGB distances for 11 galaxies from ∼4 to ∼15 Mpc, based on the first year of PHANGS-HST observations. Five of these represent the first published TRGB distance measurements (IC 5332, NGC 2835, NGC 4298, NGC 4321, and NGC 4328), and eight of which are the best available distances to these targets. We also provide a compilation of distances for the 118 galaxies in the full PHANGS sample, which have been adopted for the first PHANGS-ALMA public data release.
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Su, Chanmin, Shuiqing Hu, Yan Hu, Natalia Erina, and Andrea Slade. "Quantitative Mechanical Mapping of Biomolecules in Fluid." MRS Proceedings 1261 (2010). http://dx.doi.org/10.1557/proc-1261-u01-05.
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AbstractThough atomic force microscopy (AFM) interrogates biological materials through mechanical interactions, achieving quantitative mechanical information such as modulus and adhesion at high resolution has been a challenging task. A technology for nanometer scale mechanical property mapping, peak force tapping (PFT), was developed to achieve high resolution imaging and quantitative mechanical measurements simultaneously. PFT controls instantaneous interaction force and record force spectroscopy at each pixel to calculate mechanical properties. A feedback loop maintains a constant peak force, a local maximum point in the force spectroscopy, at the level of Pico Newtons throughout the imaging process. Such high precision force controls enable application of ultra-sharp probe to image biological samples in vitro and achieve molecular resolution in protein membranes. More importantly a full suite of mechanical properties, modulus, adhesion, energy dissipation and deformation are mapped concurrent with topographic imaging. To calculate nanomechanical properties reliably cantilever spring constant and tip shape were calibrated systematically. A method to accurately determine cantilever spring constant, capable of wafer scale cantilever calibration, was developed and tested against traceable force methods. With the knowledge of tip shape, derived from morphological dilation method using a reference sample, mechanical properties measured at the nanometer scale was compared with bench mark materials ranging from 0.7 MPa to 70 GPa. The same method was also applied to OmpG membranes, Lambda DNA strings, as well as live cells. The limitation of the measurement accuracy in biology samples will be discussed.
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Aspart, Florian, Jon L. Bolmgren, Joël L. Lavanchy, Guido Beldi, Michael S. Woods, Nicolas Padoy, and Enes Hosgor. "ClipAssistNet: bringing real-time safety feedback to operating rooms." International Journal of Computer Assisted Radiology and Surgery, July 23, 2021. http://dx.doi.org/10.1007/s11548-021-02441-x.
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Abstract Purpose Cholecystectomy is one of the most common laparoscopic procedures. A critical phase of laparoscopic cholecystectomy consists in clipping the cystic duct and artery before cutting them. Surgeons can improve the clipping safety by ensuring full visibility of the clipper, while enclosing the artery or the duct with the clip applier jaws. This can prevent unintentional interaction with neighboring tissues or clip misplacement. In this article, we present a novel real-time feedback to ensure safe visibility of the instrument during this critical phase. This feedback incites surgeons to keep the tip of their clip applier visible while operating. Methods We present a new dataset of 300 laparoscopic cholecystectomy videos with frame-wise annotation of clipper tip visibility. We further present ClipAssistNet, a neural network-based image classifier which detects the clipper tip visibility in single frames. ClipAssistNet ensembles predictions from 5 neural networks trained on different subsets of the dataset. Results Our model learns to classify the clipper tip visibility by detecting its presence in the image. Measured on a separate test set, ClipAssistNet classifies the clipper tip visibility with an AUROC of 0.9107, and 66.15% specificity at 95% sensitivity. Additionally, it can perform real-time inference (16 FPS) on an embedded computing board; this enables its deployment in operating room settings. Conclusion This work presents a new application of computer-assisted surgery for laparoscopic cholecystectomy, namely real-time feedback on adequate visibility of the clip applier. We believe this feedback can increase surgeons’ attentiveness when departing from safe visibility during the critical clipping of the cystic duct and artery.
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Fach, Christian, Nico Rödel, Jürgen Schorr, Christian Krüger, Andreas Dreizler, and Benjamin Böhm. "Investigation of in-cylinder soot formation in a DISI engine during transient operation by simultaneous endoscopic PIV and flame imaging." International Journal of Engine Research, February 22, 2022, 146808742210797. http://dx.doi.org/10.1177/14680874221079764.
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A single-cylinder full-metal engine with a real combustion chamber geometry was used to investigate particulate number emissions resulting from transient engine operation. The formation of particulate number emissions depends on mixture formation influenced by the in-cylinder flow and injection, and the formation of fuel films on the in-cylinder walls. For the investigation of this multi-parameter process, simultaneous endoscopic PIV and combustion visualization were applied. Hence, the measurement techniques allowed the investigation of in-cylinder flow, flame propagation, and soot formation. The test rig was modified to apply a generic load step and a realistic tip-in with Miller cycle. The reproducibility of the engine parameters during the transient allowed statistical analysis and the comparison between steady-state operating points. Cause-and-effect chains concerning the formation of soot are concluded by correlation analysis of parameters extracted from the flow field, the flame propagation and the soot luminosity.
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Owen, David M., Ares J. Rosakis, and William L. Johnson. "Dynamic Failure Mechanisms in Beryllium-Bearing Bulk Metallic Glasses." MRS Proceedings 554 (1998). http://dx.doi.org/10.1557/proc-554-419.
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AbstractThe understanding of dynamic failure mechanisms in bulk metallic glasses is important for the application of this class of materials to a variety of engineering problems. This is true not only for design environments in which components are subject to high loading rates, but also when components are subjected to quasi-static loading conditions where observations have been made of damage propagation occurring in an unstable, highly dynamic manner. This paper presents preliminary results of a study of the phenomena of dynamic crack initiation and growth as well as the phenomenon of dynamic localization (shear band formation) in a beryllium-bearing bulk metallic glass, Zr41.25Ti13.75Ni10Cu12.75Be22.5. Pre-notched and prefatigued plate specimens were subjected to quasi-static and dynamic three-point bend loading to investigate crack initiation and propagation. Asymmetric impact loading with a gas gun was used to induce dynamic shear band growth. The mechanical fields in the vicinity of the dynamically loaded crack or notch tip were characterized using high-speed optical diagnostic techniques. The results demonstrated a dramatic increase in the crack initiation toughness with loading rate and subsequent crack tip speeds approaching 1000 m s−1. Dynamic crack tip branching was also observed under certain conditions. Shear bands formed readily under asymmetric impact loading. The shear bands traveled at speeds of approximately 1300 m s−1 and were accompanied by intense localized heating measured using high-speed full-field infrared imaging. The maximum temperatures recorded across the shear bands were in excess of 1500 K.
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Balois, Maria Vanessa, Norihiko Hayazawa, Satoshi Yasuda, Katsuyoshi Ikeda, Bo Yang, Emiko Kazuma, Yasuyuki Yokota, Yousoo Kim, and Takuo Tanaka. "Visualization of subnanometric phonon modes in a plasmonic nano-cavity via ambient tip-enhanced Raman spectroscopy." npj 2D Materials and Applications 3, no. 1 (October 14, 2019). http://dx.doi.org/10.1038/s41699-019-0121-7.
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Abstract Phonons provide information on the physicochemical properties of a crystalline lattice from the material’s vibrational spectrum. Optical phonons, in particular, can be probed at both micrometre and nanometre scales using light-based techniques, such as, micro-Raman and tip-enhanced Raman spectroscopy (TERS), respectively. Selection rules, however, govern the accessibility of the phonons and, hence, the information that can be extracted about the sample. Herein, we simultaneously observe both allowed and forbidden optical phonon modes of defect-free areas in monolayer graphene to study nanometre scale strain variations and plasmonic activation of the Raman peaks, respectively, using our home-built TERS system in ambient. Through TERS imaging, strain variations and nanometre-sized domains down to 5 nm were visualised with a spatial resolution of 0.7 nm. Moreover, such subnanometric confinement was found to activate not only the D and D’ forbidden phonon modes but also their D + D’ combination mode. With our TERS in ambient system, the full phonon characterisation of defect-free graphene and other 2D nanomaterials is now possible, which will be useful for subnanometre strain analysis and exploring the inherent properties of defect-free materials.
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Wheeler, Amanda, and Sarah McLaughlin. "Paget Disease of the Breast." DeckerMed CGSO Case-Based Reviews, October 13, 2017. http://dx.doi.org/10.2310/cgso.16133.
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Paget disease of the breast is an in situ malignancy located within the epidermal layer of the nipple-areolar complex. It accounts for 0.5% of all breast cancers in women and 1 to 3% of new breast cancers diagnosed annually in the United States. Patients most likely present with erosion at the tip or base of the nipple. These symptoms are often confused with the symptoms of eczema. Persistent itching can occur. As the disease progresses, ulceration of the nipple expands outward over the areola. Full-thickness biopsy of the nipple or involved skin is needed to confirm diagnosis. Further workup includes mammography and, frequently, breast magnetic resonance imaging to rule out an associated breast parenchymal malignancy. Surgical excision requires removal of the nipple and involved areolar complex as well as any underlying malignancy. Mastectomy is also an option and may be required if additional multicentric disease is present. This review contains 10 figures, 6 tables, and 52 references. Key words: breast conservation, breast magnetic resonance imaging, eczema, intraepithelial adenocarcinoma, nipple abnormalities, nipple biopsy, occult malignancy, Paget disease
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Wheeler, Amanda, and Sarah McLaughlin. "Paget Disease of the Breast." DeckerMed Complex General Surgical Oncology, October 13, 2017. http://dx.doi.org/10.2310/7800.16133.
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Paget disease of the breast is an in situ malignancy located within the epidermal layer of the nipple-areolar complex. It accounts for 0.5% of all breast cancers in women and 1 to 3% of new breast cancers diagnosed annually in the United States. Patients most likely present with erosion at the tip or base of the nipple. These symptoms are often confused with the symptoms of eczema. Persistent itching can occur. As the disease progresses, ulceration of the nipple expands outward over the areola. Full-thickness biopsy of the nipple or involved skin is needed to confirm diagnosis. Further workup includes mammography and, frequently, breast magnetic resonance imaging to rule out an associated breast parenchymal malignancy. Surgical excision requires removal of the nipple and involved areolar complex as well as any underlying malignancy. Mastectomy is also an option and may be required if additional multicentric disease is present. This review contains 10 figures, 6 tables, and 52 references. Key words: breast conservation, breast magnetic resonance imaging, eczema, intraepithelial adenocarcinoma, nipple abnormalities, nipple biopsy, occult malignancy, Paget disease
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Yarotski, Dzmitry, and Antoinette J. Taylor. "High spatial resolution ultrafast scanning tunneling microscopy." MRS Proceedings 738 (2002). http://dx.doi.org/10.1557/proc-738-g3.1.
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ABSTRACTWe demonstrate ultrafast dynamical imaging of surfaces using a scanning tunneling microscope with a low-temperature-grown GaAs tip photoexcited by 100-fs, 800-nm pulses. We detect picosecond transients on a coplanar stripline and demonstrate a temporal resolution (full-width at half maximum) of 1.7 ps. By dynamically imaging the stripline, we demonstrate that the local conductivity in the sample is reflected in the transient correlated current and that 20-nm spatial resolution is achievable for a 2 ps transient, correlated signal. We apply this technique of photoconductively-gated ultrafast scanning tunneling microscopy to study carrier dynamics in InAs/GaAs self-assembled quantum dot samples at T=300 K. The initial carrier relaxation proceeds via Auger carrier capture from the InAs wetting layer (WL) on a timescale of 1–2 ps, followed by recombination of carriers on a 900 ps timescale. Finally, we demonstrate junction-mixing ultrafast STM (JM-USTM) using picosecond voltage pulses propagating on a patterned metal-on-metal (Ti/Pt). Using JM-USTM we have achieved a spatio/temporal resolution of 1 nm/8 ps.
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Sonkusare, Saurabh, Michael Breakspear, Tianji Pang, Vinh Thai Nguyen, Sascha Frydman, Christine Cong Guo, and Matthew J. Aburn. "Data-driven analysis of facial thermal responses and multimodal physiological consistency among subjects." Scientific Reports 11, no. 1 (June 8, 2021). http://dx.doi.org/10.1038/s41598-021-91578-5.
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AbstractFacial infra-red imaging (IRI) is a contact-free technique complimenting the traditional psychophysiological measures to characterize physiological profile. However, its full potential in affective research is arguably unmet due to the analytical challenges it poses. Here we acquired facial IRI data, facial expressions and traditional physiological recordings (heart rate and skin conductance) from healthy human subjects whilst they viewed a 20-min-long unedited emotional movie. We present a novel application of motion correction and the results of spatial independent component analysis of the thermal data. Three distinct spatial components are recovered associated with the nose, the cheeks and respiration. We first benchmark this methodology against a traditional nose-tip region-of-interest based technique showing an expected similarity of signals extracted by these methods. We then show significant correlation of all the physiological responses across subjects, including the thermal signals, suggesting common dynamic shifts in emotional state induced by the movie. In sum, this study introduces an innovative approach to analyse facial IRI data and highlights the potential of thermal imaging to robustly capture emotion-related changes induced by ecological stimuli.