Rhodium-catalyzed borylative carbon monoxide reduction to gem-diborylmethane

Herein, we developed a rhodium-catalyzed reduction of CO with bis(pinacolato)diboron (B2pin2) under atmospheric pressure of CO with silane as the hydride source, gem-diborylmethane [H2C(Bpin)2] as a versatile and fundamental C1 compound can be formed. Notably, this is the first example on transition metal-catalyzed borylation of CO. © 2020 The Author(s

Accelerated Life Test and FEM Simulation-Based Fatigue Analysis of an Aluminum Alloy Push Rod

The accelerated life test based on the spectrum of fatigue loads was used both in numericalsimulation and bench tests of the push rod. The symmetrical cycling of the push rod was presented asthe positive pulsating load spectrum corresponding to the stress spectrum of the critical node in thefinite element model. As FEM analysis demonstrates, the fatigue crack initiation would occur at theedge of the first-position pin hole with maximum stress and minimum fatigue life. Bench test results show that the fatigue crack initiation and fatigue life of the push rod are in good agreement with FEM data.Спектр усталостного нагружения при ускоренном испытании на долговечность использован как при численном моделировании, так и при стендовых испытаниях толкателя. Симметричный спектр толкателя был упрощен как положительный спектр пульсирующей нагрузки согласно спектру напряжений критического узла в конечноэлементной модели. Результаты анализа, полученные с помощью модели, свидетельствуют о том, что усталостная трещина зарождается на краю точечного отверстия в первом положении с максимальным напряжением и минимальной усталостной долговечностью. Согласно стендовым испытаниям зарождение усталостных трещин и усталостная долговечность толкателя хорошо согласуются с результатами анализа на конечноэлементной модели.Спектр втомного навантаження при прискореному випробуванні на довговічність використаний як при чисельному моделюванні, так і при стендових випробуваннях штовхача. Симетричний спектр штовхача був спрощений як позитивний спектр пульсуючого навантаження згідно спектру напружень критичного вузла в скінченноелементної моделі. Результати аналізу, отримані за допомогою моделі, свідчать про те, що втомна тріщина зароджується на краю точкового отвору в першому положенні з максимальним напруженням і мінімальної втомної довговічністю. Згідно стендовим випробуванням зародження втомних тріщин і втомна довговічність штовхача добре узгоджуються з результатами аналізу на скінченноелементної моделі

Effects of Irradiation Temperature and Dose Rate on the Mechanical Properties of Self-Ion Implanted Fe and Fe-Cr Alloys

Pure Fe and model Fe-Cr alloys containing 5, 10 and 14%Cr were irradiated with Fe+ ions at a maximum energy of 2MeV to the same dose of 0.6dpa at temperatures of 300 C, 400 C and 500 C, and at dose rates corresponding to 6 x 10-4 dpa/s and 3 x 10-5 dpa/s. All materials exhibited an increase in hardness after irradiation at 300 C. After irradiation at 400 C, hardening was observed only in Fe-Cr alloys, and not in the pure Fe. After irradiation at 500 C, no hardening was observed in any of the materials tested. For irradiations at both 300 C and 400 C, greater hardening was found in the Fe-Cr alloys irradiated at the lower dose rate. Transmission electron microscopy and atom probe tomography of Fe 5%Cr identified larger dislocation loop densities and sizes in the alloy irradiated with the high dose rate and Cr precipitation in the alloy irradiated with the low dose rate.Comment: 42 pages, 6 figure

On oriented graphs with minimal skew energy

Let $S(G^\sigma)$ be the skew-adjacency matrix of an oriented graph $G^\sigma$. The skew energy of $G^\sigma$ is defined as the sum of all singular values of its skew-adjacency matrix $S(G^\sigma)$. In this paper, we first deduce an integral formula for the skew energy of an oriented graph. Then we determine all oriented graphs with minimal skew energy among all connected oriented graphs on $n$ vertices with $m \ (n\le m < 2(n-2))$ arcs, which is an analogy to the conjecture for the energy of undirected graphs proposed by Caporossi {\it et al.} [G. Caporossi, D. Cvetkovi$\acute{c}$, I. Gutman, P. Hansen, Variable neighborhood search for extremal graphs. 2. Finding graphs with external energy, J. Chem. Inf. Comput. Sci. 39 (1999) 984-996.]Comment: 15 pages. Actually, this paper was finished in June 2011. This is an updated versio

Development of treatment train based on green technologies for removal and recovery of naphthenic acids from oil-sand process affected wastewater

Each day large volumes of oil sands process-affected water (OSPW) are being produced during the extraction of bitumen in oil sands industry in northern Alberta. OSPW contains different polyaromatic hydrocarbons (PAHs), bitumen, as well as naphthenic acids (NAs), which not only are the major source of toxicity in OSPW, but also create operational problems such as corrosion of the equipment during bitumen recovery process. A recent figure indicates that about 720 billion liters of OSPW that were produced during the extraction of bitumen from Canadian oil sands industry have been stored in tailing ponds that cover approximately 170 km2. Water treatment and management strategies are urgently needed for OSPW recycling in order to reduce the withdrawal of fresh water from the Athabasca River and to permit the safe release of treated OSPW to the receiving environment by removing these compounds. OSPW is highly saline water with myriad of organic and inorganic constituents, including metals, anions, organic compounds, and suspended particles. Among all the different treatment methods, adsorption has gained significant attention due to its efficiency and fast removal rates. Recent studies on petroleum coke (PC), a relatively inexpensive and abundant feedstock, used as an adsorbent after activation, have brought renewed attention to the use of adsorption processes for OSPW treatment. The coagulation/flocculation (CF) process is widely used as a pre-treatment to other processes including adsorption. Besides adsorption, desorption of exhausted adsorbents is crucial to naphthenic acids recovery due to various industrial applications. The unique properties of the metallic soaps of naphthenic acids account for the major uses of the acid. The salts of naphthenic acids (alkali naphthenates) are applied as both emulsifying and demulsifying agents. The metallic naphthenates have also found industrial application in the fields of preservatives and driers. Copper and zinc naphthenates are effective insecticides and fungicides, and solutions of these salts in petroleum solvents are available commercially. Please click Additional Files below to see the full abstract

R & D of prototype iTOF-MRPC at CEE

The cooling storage ring (CSR) external-target experiment (CEE) is a spectrometer running at the Heavy Ion Research Facility (HIRFL) at Lanzhou. The CEE is the first large-scale nuclear physics experimental device by China to operate in the fixed-target mode with an energy of 1 GeV. The purpose of the CEE is to study the properties of dense nuclear matter. CEE uses a multi-gap resistive plate chamber (MRPC) as its internal time-of-flight (iTOF) detector for the identification of final-state particles. An iTOF-MRPC prototype with 24 gaps was designed to meet the requirements of CEE, and the readout electronics of the prototype use the FPGA-based time digitization technology. Using cosmic ray tests, the time resolution of the iTOF prototype was found to be approximately 30 ps. In order to further understand how to improve the time resolution of MRPC, ANSYS HFSS was used to simulate the signal transmission process in MRPC. The main factors affecting the timing performance of the MRPC and, accordingly, the optimization scheme are presented.Comment: 11 pages,9 figure

Quantification of Myocardial Dosimetry and Glucose Metabolism Using a 17-Segment Model of the Left Ventricle in Esophageal Cancer Patients Receiving Radiotherapy

Objective Previous studies have shown that increased cardiac uptake of(18)F-fluorodeoxyglucose (FDG) on positron emission tomography (PET) may be an indicator of myocardial injury after radiotherapy (RT). The primary objective of this study was to quantify cardiac subvolume dosimetry and(18)F-FDG uptake on oncologic PET using a 17-segment model of the left ventricle (LV) and to identify dose limits related to changes in cardiac(18)F-FDG uptake after RT. Methods Twenty-four esophageal cancer (EC) patients who underwent consecutive oncologic(18)F-FDG PET/CT scans at baseline and post-RT were enrolled in this study. The radiation dose and the(18)F-FDG uptake were quantitatively analyzed based on a 17-segment model. The(18)F-FDG uptake and doses to the basal, middle and apical regions, and the changes in the(18)F-FDG uptake for different dose ranges were analyzed. Results A heterogeneous dose distribution was observed, and the basal region received a higher median mean dose (18.36 Gy) than the middle and apical regions (5.30 and 2.21 Gy, respectively). Segments 1, 2, 3, and 4 received the highest doses, all of which were greater than 10 Gy. Three patterns were observed for the myocardial(18)F-FDG uptake in relation to the radiation dose before and after RT: an increase (5 patients), a decrease (13 patients), and no change (6 patients). In a pairing analysis, the(18)F-FDG uptake after RT decreased by 28.93 and 12.12% in the low-dose segments (0-10 Gy and 10-20 Gy, respectively) and increased by 7.24% in the high-dose segments (20-30 Gy). Conclusion The RT dose varies substantially within LV segments in patients receiving thoracic EC RT. Increased(18)F-FDG uptake in the myocardium after RT was observed for doses above 20 Gy.</div