The capacity of soil as a carbon (C) sink is mediated by interactions between organic matter and mineral phases. However, previously proposed layered accumulation of organic matter within aggregate ...organo-mineral microstructures has not yet been confirmed by direct visualization at the necessary nanometer-scale spatial resolution. Here, we identify disordered micrometer-size organic phases rather than previously reported ordered gradients in C functional groups. Using cryo-electron microscopy with electron energy loss spectroscopy (EELS), we show organo-organic interfaces in contrast to exclusively organo-mineral interfaces. Single-digit nanometer-size layers of C forms were detected at the organo-organic interface, showing alkyl C and nitrogen (N) enrichment (by 4 and 7%, respectively). At the organo-mineral interface, 88% (72-92%) and 33% (16-53%) enrichment of N and oxidized C, respectively, indicate different stabilization processes than at organo-organic interfaces. However, N enrichment at both interface types points towards the importance of N-rich residues for greater C sequestration.
Pyrogenic carbon contains redox-active functional groups and polyaromatic carbon matrices that are both capable of transferring electrons. Several techniques have been explored to characterize the ...individual electron transfer process of either functional groups or carbon matrices individually. However, simultaneous analysis of both processes remains challenging. Using an approach that employs a four-electrode configuration and dual-interface electron transfer detection, we distinguished the electron transfer by functional groups from the electron transfer by carbon matrices and simultaneously quantified their relative contribution to the total electron transfer to and from pyrogenic carbon. Results show that at low to intermediate pyrolysis temperatures (400–500 °C), redox cycling of functional groups is the major mechanism with a contribution of 100–78% to the total electron transfer; whereas at high temperatures (650–800 °C), direct electron transfer of carbon matrices dominates electron transfer with a contribution of 87–100%. Spectroscopic and diffraction analyses of pyrogenic carbon support the electrochemical measurements by showing a molecular-level structural transition from an enrichment in functional groups to an enrichment in nanosized graphene domains with increasing pyrolysis temperatures. The method described in this study provides a new analytical approach to separately quantify the relative importance of different electron transfer pathways in natural pyrogenic carbon and has potential applications for engineered carbon materials such as graphene oxides.
In the United States, colorectal cancer (CRC) is the third most common cancer diagnosed among men and women and the second leading cause of death from cancer. CRC largely can be prevented by the ...detection and removal of adenomatous polyps, and survival is significantly better when CRC is diagnosed while still localized. In 2006 to 2007, the American Cancer Society, the US Multi Society Task Force on Colorectal Cancer, and the American College of Radiology came together to develop consensus guidelines for the detection of adenomatous polyps and CRC in asymptomatic average‐risk adults. In this update of each organization's guidelines, screening tests are grouped into those that primarily detect cancer early and those that can detect cancer early and also can detect adenomatous polyps, thus providing a greater potential for prevention through polypectomy. When possible, clinicians should make patients aware of the full range of screening options, but at a minimum they should be prepared to offer patients a choice between a screening test that is effective at both early cancer detection and cancer prevention through the detection and removal of polyps and a screening test that primarily is effective at early cancer detection. It is the strong opinion of these 3 organizations that colon cancer prevention should be the primary goal of screening.
Atomic vibrations control all thermally activated processes in materials, including diffusion, heat transport, phase transformations and surface chemistry. Recent developments in scanning ...transmission electron microscopy (STEM) have enabled nanoscale probing of vibrational modes using electron energy-loss spectroscopy (EELS)1,2. Although atomically resolved analysis is routine in STEM, vibrational spectroscopy employing oscillating dipoles yields signals originating from regions tens of nanometres in size, because the scattering angles are only a few microradians3. Recently, it has been shown that energy-filtered images recorded at high scattering angles display atomic resolution4. Here we show, using conventional on-axis EELS, that non-dipole, impact scattering vibrational signals are present, and exhibit atomic resolution. This on-axis signal shows variations in the spectral peak shape and intensity as the electron probe is scanned across an individual atomic column in a Si sample. Although atomic spatial resolution in coherent elastic scattering will complicate the quantitative interpretation of spectra from crystals, the change in peak shape provides compelling evidence that the vibrational EELS excitation process is highly localized. High spatial resolution is also demonstrated in SiO2, an amorphous polar material. Our approach represents an important technical advance that will provide new insights into the local thermal, elastic and kinetic properties of materials.
Abstract
We report the discovery of PSR J1757−1854, a 21.5-ms pulsar in a highly-eccentric, 4.4-h orbit with a neutron star (NS) companion. PSR J1757−1854 exhibits some of the most extreme ...relativistic parameters of any known pulsar, including the strongest relativistic effects due to gravitational-wave damping, with a merger time of 76 Myr. Following a 1.6-yr timing campaign, we have measured five post-Keplerian parameters, yielding the two component masses (mp = 1.3384(9) M⊙ and mc = 1.3946(9) M⊙) plus three tests of general relativity, which the theory passes. The larger mass of the NS companion provides important clues regarding the binary formation of PSR J1757−1854. With simulations suggesting 3-σ measurements of both the contribution of Lense–Thirring precession to the rate of change of the semimajor axis and the relativistic deformation of the orbit within ∼7–9 yr, PSR J1757−1854 stands out as a unique laboratory for new tests of gravitational theories.
This study aims to compare the tracking algorithms provided by the OpenCV library to use on ultrasound video. Despite the widespread application of this computer vision library, few works describe ...the attempts to use it to track the movement of liver tumors on ultrasound video. Movements of the neoplasms caused by the patient`s breath interfere with the positioning of the instruments during the process of biopsy and radio-frequency ablation. The main hypothesis of the experiment was that tracking neoplasms and correcting the position of the manipulator in case of using robotic-assisted surgery will allow positioning the instruments more precisely. Another goal of the experiment was to check if it is possible to ensure real-time tracking with at least 25 processed frames per second for standard definition video. OpenCV version 4.5.0 was used with 7 tracking algorithms from the extra modules package. They are: Boosting, CSRT, KCF, MedianFlow, MIL, MOSSE, TLD. More than 5600 frames of standard definition were processed during the experiment. Analysis of the results shows that two algorithms-CSRT and KCF-could solve the problem of tumor tracking. They lead the test with 70% and more of Intersection over Union and more than 85% successful searches. They could also be used in real-time processing with an average processing speed of up to frames per second in CSRT and 100 + frames per second for KCF. Tracking results reach the average deviation between centers of neoplasms to 2 mm and maximum deviation less than 5 mm. This experiment also shows that no frames made CSRT and KCF algorithms fail simultaneously. So, the hypothesis for future work is combining these algorithms to work together, with one of them-CSRT-as support for the KCF tracker on the rarely failed frames.
ABSTRACT
We present the results of processing an additional 44 per cent of the High Time Resolution Universe South Low Latitude (HTRU-S LowLat) pulsar survey, the most sensitive blind pulsar survey ...of the southern Galactic plane to date. Our partially coherent segmented acceleration search pipeline is designed to enable the discovery of pulsars in short, highly accelerated orbits, while our 72-min integration lengths will allow us to discover pulsars at the lower end of the pulsar luminosity distribution. We report the discovery of 40 pulsars, including three millisecond pulsar-white dwarf binary systems (PSRs J1537−5312, J1547−5709, and J1618−4624), a black-widow binary system (PSR J1745−23) and a candidate black-widow binary system (PSR J1727−2951), a glitching pulsar (PSR J1706−4434), an eclipsing binary pulsar with a 1.5-yr orbital period (PSR J1653−45), and a pair of long spin-period binary pulsars which display either nulling or intermittent behaviour (PSRs J1812−15 and J1831−04). We show that the total population of 100 pulsars discovered in the HTRU-S LowLat survey to date represents both an older and lower luminosity population, and indicates that we have yet to reach the bottom of the luminosity distribution function. We present evaluations of the performance of our search technique and of the overall yield of the survey, considering the 94 per cent of the survey which we have processed to date. We show that our pulsar yield falls below earlier predictions by approximately 25 per cent (especially in the case of millisecond pulsars), and discuss explanations for this discrepancy as well as future adaptations in RFI mitigation and searching techniques which may address these shortfalls.
Our experimental studies of electron transport in wide (14 nm) HgTe quantum wells confirm the persistence of a two-dimensional topological insulator state reported previously for narrower wells, ...where it was justified theoretically. Comparison of local and nonlocal resistance measurements indicate edge state transport in the samples of about 1 mm size at temperatures below 1 K. Temperature dependence of the resistances suggests an insulating gap of the order of a few meV. In samples with sizes smaller than 10 μm a quasiballistic transport via the edge states is observed.
Ni-rich LiNi x Mn y Co1‑x‑y O2 (x > 0.5) (NMC) materials have attracted a great deal of interest as promising cathode candidates for Li-ion batteries due to their low cost and high energy density. ...However, several issues, including sensitivity to moisture, difficulty in reproducibly preparing well-controlled morphology particles and, poor cyclability, have hindered their large scale deployment; especially for electric vehicle (EV) applications. In this work, we have developed a uniform, highly stable, high-energy density, Ni-rich LiNi0.6Mn0.2Co0.2O2 cathode material by systematically optimizing synthesis parameters, including pH, stirring rate, and calcination temperature. The particles exhibit a spherical morphology and uniform size distribution, with a well-defined structure and homogeneous transition-metal distribution, owing to the well-controlled synthesis parameters. The material exhibited superior electrochemical properties, when compared to a commercial sample, with an initial discharge capacity of 205 mAh/g at 0.1 C. It also exhibited a remarkable rate capability with discharge capacities of 157 mAh/g and 137 mAh/g at 10 and 20 C, respectively, as well as high tolerance to air and moisture. In order to demonstrate incorporation into a commercial scale EV, a large-scale 4.7 Ah LiNi0.6Mn0.2Co0.2O2 Al-full pouch cell with a high cathode loading of 21.6 mg/cm2, paired with a graphite anode, was fabricated. It exhibited exceptional cyclability with a capacity retention of 96% after 500 cycles at room temperature. This material, which was obtained by a fully optimized scalable synthesis, delivered combined performance metrics that are among the best for NMC materials reported to date.
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