14,999 research outputs found

    A review of process advancement of novel metal spinning

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    Metal spinning technology has seen a rapid development in recent years. Novel spinning processes, such as non-axisymmetrical spinning, non-circular cross-section spinning and tooth-shaped spinning, are being developed. This has challenged the limitation of traditional spinning technology being used for manufacturing axisymmetrical, circular cross-section, and uniform wall-thickness parts. In this paper, the classification of the traditional spinning processes is proposed based on the material deformation characteristics, the relative position between roller and blank, mandrel spinning and mandrel-free spinning, and temperature of the blank during spinning. The advancement of recently developed novel spinning processes and corresponding tool design and equipment development are reviewed. The classification of the novel spinning processes is proposed based on the relative position between the rotating axes, the geometry of cross-section and the variation of wall-thickness of the spun parts. The material deformation mechanism, processing failures and spun part defects of the aforementioned three groups of novel spinning processes are discussed by analyzing four representative spinning processes of industrial applications. Furthermore, other novel spinning processes and their classification as reported in the literature are summarized

    Momentum Distribution of Near-Zero-Energy Photoelectrons in the Strong-Field Tunneling Ionization in the Long Wavelength Limit

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    We investigate the ionization dynamics of Argon atoms irradiated by an ultrashort intense laser of a wavelength up to 3100 nm, addressing the momentum distribution of the photoelectrons with near-zero-energy. We find a surprising accumulation in the momentum distribution corresponding to meV energy and a \textquotedblleft V"-like structure at the slightly larger transverse momenta. Semiclassical simulations indicate the crucial role of the Coulomb attraction between the escaping electron and the remaining ion at extremely large distance. Tracing back classical trajectories, we find the tunneling electrons born in a certain window of the field phase and transverse velocity are responsible for the striking accumulation. Our theoretical results are consistent with recent meV-resolved high-precision measurements.Comment: 5 pages, 4 figure

    KDM2B/FBXL10 targets c-Fos for ubiquitylation and degradation in response to mitogenic stimulation.

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    KDM2B (also known as FBXL10) controls stem cell self-renewal, somatic cell reprogramming and senescence, and tumorigenesis. KDM2B contains multiple functional domains, including a JmjC domain that catalyzes H3K36 demethylation and a CxxC zinc-finger that recognizes CpG islands and recruits the polycomb repressive complex 1. Here, we report that KDM2B, via its F-box domain, functions as a subunit of the CUL1-RING ubiquitin ligase (CRL1/SCF(KDM2B)) complex. KDM2B targets c-Fos for polyubiquitylation and regulates c-Fos protein levels. Unlike the phosphorylation of other SCF (SKP1-CUL1-F-box)/CRL1 substrates that promotes substrates binding to F-box, epidermal growth factor (EGF)-induced c-Fos S374 phosphorylation dissociates c-Fos from KDM2B and stabilizes c-Fos protein. Non-phosphorylatable and phosphomimetic mutations at S374 result in c-Fos protein which cannot be induced by EGF or accumulates constitutively and lead to decreased or increased cell proliferation, respectively. Multiple tumor-derived KDM2B mutations impaired the function of KDM2B to target c-Fos degradation and to suppress cell proliferation. These results reveal a novel function of KDM2B in the negative regulation of cell proliferation by assembling an E3 ligase to targeting c-Fos protein degradation that is antagonized by mitogenic stimulations

    Constraints on timing of the early-paleoproterozoic magmatism and crustal evolution of the Oulongbuluke microcontinent: U-Pb and Lu-Hf isotope systematics of zircons from Mohe granitic pluton

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    The Olongbuluke micro-continent is composed of a two-fold basement with cover strata. The lower basement is the medium-to high-grade Delingha complex (DC) and the Dakendaban Group, the upper is the low-grade Wandonggou Group. Zircon LA-ICP-MS dating gives U-Pb isotope of 27 zircon grains from the Mohe granite of the DC, of which 26 zircon grains suffered various degree of Pb loss and defined a Concordia with a upper intercept age of 2470 +19/-18Ma. Hf isotope of 25 zircon grains was measured using LA-MC-ICP-MS technique, of which 23 grains crystallized from Mohe granite show Hf(2470Ma) = 0.28129-0.28140 (weighted average of 0.28134±0.00003). εHf = 2.94-6.95(weighted average of 4.58 + 0.54/-0.76), resident time for the felsic crustal reservoir TcDM=2.54-2.75 Ga with weighted average of 2.66 + 0.04/-0.02Ga. These data indicate that the Mohe granite pluton was derived from partial melting of the mantle, and the intrusion of the Mohe granite pluton implied a crustal accretion event occurred in Olongbuluke micro-continent at ca. 2.5 Ga.欧龙布鲁克微陆块具典型的基底与盖层二元结构,基底自下而上由德令哈杂岩、达肯大坂岩群和万洞沟群三个岩石-构造单元组成。应用LA-ICP-MS测定了德令哈杂岩中的莫河花岗岩体的27个颗锆石的U-Pb同位索成分,其中26颗锆石发生不同程度的放射成因铅同位素丢失,其不一致线上交点年龄为2470+19/-18Ma。应用LA-MC-ICP-MS测定了25颗锆石的Hf同位索成分,其中岩浆结晶成因的23颗锆石的Hf(2470Ma)=0.28129-0.28140,平均值0.28134±0.00003;εHf值的变化范围2.94-6.95,加权平均值4.58+0.54/-0.76,长英质地壳存留年龄TcDM=2.54-2.75Ga,加权平均值2.66+0.04/-0.02Ga。以上数据将该花岗岩的形成年龄约束在2470Ma,其岩浆来源于地幔物质的部分熔融,指示欧龙布鲁克微陆块在-2.5Ga的地壳增生事件。published_or_final_versio

    The Properties of H{\alpha} Emission-Line Galaxies at z = 2.24

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    Using deep narrow-band H2S1H_2S1 and KsK_{s}-band imaging data obtained with CFHT/WIRCam, we identify a sample of 56 Hα\alpha emission-line galaxies (ELGs) at z=2.24z=2.24 with the 5σ\sigma depths of H2S1=22.8H_2S1=22.8 and Ks=24.8K_{s}=24.8 (AB) over 383 arcmin2^{2} area in the ECDFS. A detailed analysis is carried out with existing multi-wavelength data in this field. Three of the 56 Hα\alpha ELGs are detected in Chandra 4 Ms X-ray observation and two of them are classified as AGNs. The rest-frame UV and optical morphologies revealed by HST/ACS and WFC3 deep images show that nearly half of the Hα\alpha ELGs are either merging systems or with a close companion, indicating that the merging/interacting processes play a key role in regulating star formation at cosmic epoch z=2-3; About 14% are too faint to be resolved in the rest-frame UV morphology due to high dust extinction. We estimate dust extinction from SEDs. We find that dust extinction is generally correlated with Hα\alpha luminosity and stellar mass (SM). Our results suggest that Hα\alpha ELGs are representative of star-forming galaxies (SFGs). Applying extinction correction for individual objects, we examine the intrinsic Hα\alpha luminosity function (LF) at z=2.24z=2.24, obtaining a best-fit Schechter function characterized by a faint-end slope of α=1.3\alpha=-1.3. This is shallower than the typical slope of α1.6\alpha \sim -1.6 in previous works based on constant extinction correction. We demonstrate that this difference is mainly due to the different extinction corrections. The proper extinction correction is thus key to recovering the intrinsic LF as the extinction globally increases with Hα\alpha luminosity. Moreover, we find that our Hα\alpha LF mirrors the SM function of SFGs at the same cosmic epoch. This finding indeed reflects the tight correlation between SFR and SM for the SFGs, i.e., the so-called main sequence.Comment: 15 pages, 12 figures, 2 tables, Received 2013 October 11; accepted 2014 February 13; published 2014 March 18 by Ap
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