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Ultrafast z-scanning for high-efficiency laser micro-machining

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Light(Science & Applications) 2018年第1期7卷 1094-1102页

作者： Ting-Hsuan Chen Romain Fardel craig b arnold Department of Mechanical and Aerospace Engineering and Princeton Institute for the Science and Technology of MaterialsPrinceton UniversityPrincetonNJ 08544USA

High-throughput laser micro-machining demands precise control of the laser beam position to achieve optimal efficiency,but existing methods can be both time-consuming and *** this paper,we demonstrate a new high-throughput micromachining technique based on rapidly scanning the laser focal point along the optical axis using an acoustically driven variable focal length *** results show that this scanning method enables higher machining rates over a range of defocus distances and that the effect becomes more significant as the laser energy is *** a specific example of silicon,we achieve a nearly threefold increase in the machining rate,while maintaining sharp side walls and a small spot *** method has great potential for improving the micro-machining efficiency of conventional systems and also opens the door to applying laser machining to workpieces with uneven topography that have been traditionally difficult to process.

关键词： high-efficiency micro-machining laser material processing TAG lens ultrafast z-scanning

Implications of using two low-power continuous-wave lasers for polishing

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International Journal of Extreme Manufacturing 2020年第3期2卷 174-182页

作者： Wenxuan Zhang Kiwan Wong Miguel Morales Carlos Molpeceres craig b arnold Department of Chemical and biological Engineering Princeton UniversityPrincetonNJ 08544United States of America Princeton Institute for the Science and Technology of Materials Princeton UniversityPrincetonNJ 08544United States of America Department of Mechanical and Aerospace Engineering The Hong Kong University of Science and TechnologyHong Kong Centro Laser UPM Universidad Politecnica de MadridAlan Turing 128031MadridSpain Department of Mechanical and Aerospace Engineering Princeton UniversityPrincetonNJ 08544United States of America

Laser polishing is widely employed to reduce the surface roughness of products with complex *** laser polishing techniques use a single high-power Gaussian beam to melt and smooth a thin layer of surface ***,the reliance on high power lasers can present practical challenges such as minimizing surface evaporation or reducing overall *** this work,we combined two identical low-power laser beams with a spatial offset in between them to construct an elliptical *** changing the spatial offset,combined beams with different lengths along the major axis can be *** observe over 20%improvement in line roughness reduction using this approach compared to a single Gaussian laser beam with the same total ***,both experiment and simulation results suggest such improvement is because this dual-laser set-up can create a longer molten pool compared to a single laser.

关键词： laser polishing surface roughness dual lasers low-power

Understanding the Rayleigh instability in humping phenomenon during laser powder bed fusion process

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International Journal of Extreme Manufacturing 2022年第1期4卷 85-92页

作者： Wenxuan Zhang Wenyuan Hou Luc Deike craig arnold Department of Chemical and biological Engineering Princeton UniversityPrincetonNJ 08544United States of America Princeton Institute for the Science and Technology of Materials Princeton UniversityPrincetonNJ 08544United States of America Department of Mechanical and Aerospace Engineering Princeton UniversityPrincetonNJ 08544United States of America High Meadows Environmental Institute Princeton UniversityPrincetonNJ 08544United States of America

The periodic undulation of a molten track’s height profile in laser-based powder bed fusion of metals(PbF-Lb/M)is a commonly observed phenomena that can cause defects and building failure during the manufacturing *** a quantitative analysis of such instabilities has not been fully established and so here we used Rayleigh–Plateau theory to determine the stability of a single molten track in PbF-Lb/M and tested it with various processing conditions by changing laser power and beam *** analysis discovered that normalized enthalpy,which relates to energy input density,determines whether a molten track is initially unstable and if so,the growth rate for the ***,whether the growth rate ultimately yields significant undulation depends on the melt duration,estimated by dwell time in our experiment.

关键词： additive manufacturing powder bed fusion dual lasers undulation humping

Serum sIL-2R,TNF-α and IFN-γ in alveolar echinococcosis

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World Journal of Gastroenterology 2004年第24期10卷 3674-3676页

作者： Da-Zhong Shi Fu-Rong Li b bartholomot DA Vuitton PS craig Department of Immunology Besancon UniversityFrance

AIM: To approach the relationship between alveolar echinococcosis (AE) pathology and level of sIL-2R,TNF-α and IFN-γ in sera and the significance of cytokines in development of ***: After 23 patients with AE were confirmed by ELISA and ultrasound, their sera were collected and the concentrations of sIL-2R,TNF-α and IFN-γ were detected by double antibody sandwich. Twelve healthy adults served as controls. According to the status of livers of AE patients by ultrasound scanning, they were divided into 4 groups: P2,P3, P4 groups and C group (control). Average of concentrations of sIL-2R, TNF-α and IFN-yin homologous group was statistically analyzed by both ANOV and Newman-Keuls, ***: The mean of sIL-2R in P2 group was 97±29, P3:226±80, P4:194±23 and control group (111±30)×10^3 u/L(Pby ANOV and Newman-Keuls, the mean concentrations of sIL-2R, TNF-α and IFN-γ had a significant difference among groups. Except for P2group, the mean sIL-2R between other groups of AE patients had a significant difference (Pbut there was no difference between AE groups (P>0.05).CONCLUSION: Low sIL-2R level indicates an early stage of AE or stable status, per contra, a progression stage. Higher level of TNF-α might be related to the lesion of liver. The role of single IFN-γ is limited in immunological defense against AE and it can not fully block pathological progression.

关键词：免疫血清 sIL-2R TNF-α IFN-γ 肺泡包虫病 AE

New Identities for Weak KAM Theory(For Haim brezis,in continuing admiration)

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Chinese Annals of Mathematics,Series b 2017年第2期38卷 379-392页

作者： Lawrence craig EVANS Department of Mathematics University of CaliforniaBerkeleyUSA.

This paper records for the Hamiltonian H =1/2|p|~2+ W(x) some old and new identities relevant for the PDE/variational approach to weak KAM theory.

关键词： Weak KAM theory, Effective Hamiltonian, Hamiltonian dynamics

Subnanometer localization accuracy in widefield optical microscopy

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Light(Science & Applications) 2018年第1期7卷 740-754页

作者： craig R.Copeland Jon Geist craig D.McGray Vladimir A.Aksyuk J.Alexander Liddle b.Robert Ilic Samuel M.Stavis Center for Nanoscale Science and Technology National Institute of Standards and TechnologyGaithersburgMD 20899USA Maryland NanoCenter University of MarylandCollege ParkMD 20742USA Engineering Physics Division National Institute of Standards and TechnologyGaithersburgMD 20899USA

The common assumption that precision is the limit of accuracy in localization microscopy and the typical absence of comprehensive calibration of optical microscopes lead to a widespread issue—overconfidence in measurement results with nanoscale statistical uncertainties that can be invalid due to microscale systematic *** this article,we report a comprehensive solution to this underappreciated *** develop arrays of subresolution apertures into the first reference materials that enable localization errors approaching the atomic scale across a submillimeter *** present novel methods for calibrating our microscope system using aperture arrays and develop aberration corrections that reach the precision limit of our reference *** correct and register localization data from multiple colors and test different sources of light emission with equal accuracy,indicating the general applicability of our reference materials and calibration *** a first application of our new measurement capability,we introduce the concept of critical-dimension localization microscopy,facilitating tests of nanofabrication processes and quality control of aperture *** a second application,we apply these stable reference materials to answer open questions about the apparent instability of fluorescent nanoparticles that commonly serve as fiducial *** study establishes a foundation for subnanometer localization accuracy in widefield optical microscopy.

关键词： optical limit field

Physiological evidence of integrin-antibody reactive proteins influencing the innate cellular immune responses of larval Galleria mellonella hemocytes

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Insect Science 2020年第2期27卷 239-255页

作者： Jason F.Lapointe Connor D.McCarthy Gary b.Dunphy craig A.Mandato Department of Anatomy and Cell biology McGill UniversityMontrealCanada Department of Natural Resource Sciences Macdonald CampusSte.Anne De BellevueCanada

Larval Galleria melonella(L.)hemocytes form microaggregates in response to stimulation by Gram-positive bacteria Hemocyte adhesion to foreign materials is mediated by the CAMP/protein kinase A pathway and the b-subunit of cholera toxin using a cAMP-independent *** toxin-induced microaggregation was inhibited by the integrin inhibitory RGDS peptide,implying integrins may be part of the *** on the types of mammalian integrin-antibody reactive proteins affecting hemocyte adhesion and bacterial-induced responses ars,ory,Ai,and b3 subunits occred on both granular cell and plasmatocyte hemocyte subtypes.A fluorescent band representing the binding of rabbit as-integrin subunit antibodies occurred between adhering heterotypic *** frequency of the bands was increased by cholera *** as andβrabbit integrin subunit antibodies inhibited removal of bacillus subtilis(Cohn)from the hemolymph in vivo,A as ir-specific synthetic peptide blocker similarly diminished hemocyte function whereas the 0v bs-specific inhibitory peptide and the corresponding integrin subunit antibodies did not influence nonself hemocyte *** blots revealed several proteins reacting with a given integrin-antibody *** integrin-antibody reactive proteins(which may include integrins)with possible as and b epitopes modulate immediate hemocyte *** microscopy established plasmatocyte adhesion to and rosetting over substrata followved by granular cell microaggregate adhesion to plasmatocytes during early stage nodulation.

关键词： hemocyte response integrin-antibody reactive protein

Tinker,tailor,soldier,cell:the role of C-type lectins in the defense and promotion of disease

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Protein & Cell 2023年第1期14卷 4-16页

作者： James N.arnold Daniel A.Mitchell School of Cancer and Pharmaceutical Sciences King's College LondonLondon SE11ULUK Warwick Medical School University of WarwickCoventry CV22DXUK

C-type lectins(CTLs)represent a large family of soluble and membrane-bound proteins which bind calcium dependently via carbohydrate recognition domains(CRDs)to glycan residues presented on the surface of a variety of *** deconvolution of a cell’s glycan code by CTLs underpins several important physiological processes in mammals such as pathogen neutralization and opsonization,leukocyte trafficking,and the inflammatory ***,as our knowledge of CTLs has developed it has become apparent that the role of this innate immune family of proteins can be double-edged,where some pathogens have developed approaches to subvert and exploit CTL interactions to promote infection and sustain the pathological ***,CTL interactions with host glycoproteins can contribute to inflammatory diseases such as arthritis and cancer whereby,in certain contexts,they exacerbate inflammation and drive malignant *** review discusses the‘dual agent’roles of some of the major mammalian CTLs in both resolving and promoting infection,inflammation and inflammatory disease and highlights opportunities and emerging approaches for their therapeutic modulation.

关键词： C-type lectins DC-SIGN MbL selectins infection arthritis cancer

Synthesis and CrystalStructure of Dicesiumtrans-Dicarbonatotetraaquom agnesium ,Cs_2[Mg(CO_3)_2(H_2O)_4]

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Chemical Research in Chinese Universities 1999年第3期15卷 211-217页

作者： ZHENG Yue-qing ADAM arnold Chemistry Department Ningbo UniversityNingbo 315211P.R.China Institute fr Anorganische Chemie Universitāt zu KlnD 50674 KlnGermany

The title compound, Cs 2[Mg(CO 3) 2(H 2O) 4], was synthesized by the dropwise addition of an aqueous solution of Mg(NO 3) 2 to a stirred aqueous Cs 2CO 3/CsHCO 3 solution. A colorless needle shaped crystal was formed by slow evaporation. The crystal structure was established on the basis of the single crystal X ray diffraction data. Cs 2[Mg(CO 3) 2(H 2O) 4] crystallized in the orthorhombic space group Pbca (No. 61) with a =0.658 4(1) nm, b =1.257 9(1) nm, c =1.301 3(1) nm, \{ V =1.077 8 nm 3, Z =4, D x=2.971 g·cm -3 , μ =69.20 cm -1 , F (000)=888, T =298 K, final R =0.029 and R w=0.024 for 1 037 observed reflections. The crystal consists of Cs + cations and the complex trans [Mg(CO 3) 2(H 2O) 4] 2- anions with each Mg atom coordinated by the six oxygens of two carbonate groups and four water molecules [ d (Mg_O)=0.203 6(4), 0.207 4(4), 0.213 4(4) nm]. The complex trans [Mg(CO 3) 2(H 2O) 4] 2- anions are arranged in a strongly compressed bcc pattern. A 3D network was formed through the intermolecular hydrogen bonds. The Cs + cations are located in cavities, each being surrounded by nine oxygens of five complex anions with d (Cs_O)=0.306 1-0.348 8 nm. The CO 2- 3 group reveals a lowering of D 3h symmetry due to site and coordination effects, but not any observable deviation from co planarity [ d (C_O)=0.127 2(6), 0.127 5(7) , 0.130 5(6) nm and O_C_O=119.6(5)°, 120.1(5)°, 120.4(5)°].

关键词： Synthesis Cs 2[Mg(CO 3) 2(H 2O) 4] Dicesium trans dicarbonatotetraaquomagnesium Crystal structure Complex carbonate