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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

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

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

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

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

Should Athletes Stretch before Exercise?

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中国运动医学杂志 2007年第5期26卷 626-633页

作者： Karl b.Fields craig M.burnworth Martha Delaney Director of Family Medicine Residency and Sports Medicine Fellowship Moses Cone Health System GreensboroNC MD Professor and Associate Chairman Department of Family MedicineUniversity of North Carolina Sports Medicine Fellow Moses Cone Health SystemGreensboroNC Associate Team PhysicianElon UniversityElonNC MD Administrative Director Greensboro Area Health Education Center Research CoordinatorMoses Cone Family Medicine Residency GreensboroNC MA

KEY POINTSTraditional stretching routines performed during warm-up procedures before exercise can increase flexibility for a short time,but there is little scientific evidence that such routines can improve exercise performance,reduce delayed-onset muscular soreness,or prevent *** on a regular basis,e.g.,3-5 days/week,away from the exercise environment may be effective in improving flexibility and some types of exercise performance,and it may reduce injury risk,but further research is required to validate this *** stretching for 15-30 seconds is more effective for increasing flexibility than stretching for shorter durations and is equally effective as stretching for longer periods.

关键词：运动伸展训练热身运动肌肉酸痛运动损伤

Flip the switch: bTG2–PRMT1 protein complexes antagonize pre-b-cell proliferation to promote b-cell development

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Cellular & Molecular Immunology 2018年第9期15卷 808-811页

作者： Glendon S Wu craig H bassing Immunology Graduate Group Children’s Hospital of PhiladelphiaPerelman School of Medicine at the University of PennsylvaniaPhiladelphiaPA 19104USA Divsion of Cancer Pathobiology Department of Pathology and Laboratory MedicineChildren’s Hospital of PhiladelphiaAbramson Family Cancer Research InstitutePerelman School of Medicine at the University of PennsylvaniaPhiladelphiaPA 19104USA

b lymphocytes are vital components of vertebrate adaptive immune ***,b-cell dysfunction can promote autoimmunity and immunodefi-ciency,and errors in development can cause b-lineage lymphoid malignancies.b-cell development requires RAG1/RAG2(RAG)endonuclease-mediated assembly of immunoglobulin(Ig)*** assembly of Ig heavy chain(IgH)genes in G1-phase pro-b cells produces IgH proteins that pair with Vpreb/λ5 to form pre-b-cell receptor(pre-bCR)*** pro-b cells,pre-bCR signaling inhibits Rag1/Rag2 transcription,stabilizes Cyclin D3 to drive cellular proliferation and promotes differentiation of large pre-b cells.

关键词： lymphocytes lymphoid complexes

Characterization and transcriptional analyses of cDNAs encoding three trypsin- and chymotrypsin-like proteinases in CrylAb-susceptible and CrylAb-resistant strains of sugarcane borer, Diatraea saccharalis

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Insect Science 2013年第4期20卷 485-496页

作者： Yunlong Yang Yu Cheng Zhu James Ottea Claudia Husseneder b. Rogers Leonard craig Abel Randall Luttrell Fangneng Huang Department of Entomology Louisiana State University Agricultural Center Baton Rouge Louisiana Southern Insect Management Research Unit Agricultural Research Service United States Department of Agriculture Stoneville Mississippi Corn Insects and Crop Genetics Research Unit Agricultural Research Service United States Department of Agriculture Ames Iowa USA

Diatraea saccharalis is a major corn borer pest. Midgut serine proteinases are essential for insect growth and development. Alteration of midgut proteinases is re- sponsible for bt resistance development in some species. To clone midgut trypsin and chymotrypsin cDNAs and to test if the CrylAb resistance in D. saccharalis is associ- ated with changes in midgut proteinases, total midgut tryptic and chymotryptic activities, cDNA sequences, and gene expressions of three trypsin and three chymotrypsin genes were comparatively examined between Cry 1 Ab-susceptible （Cry 1 Ab- S S） and Cry 1 Ab-resistant （Cry 1 Ab-RR） strains. Full-length cDNAs encoding three trypsin- and three chymotrypsin- like proteinases were sequenced from CrylAb-SS and CrylAb-RR larvae. These cDNAs code for active forms of midgut serine proteinases with all fimctional motifs, includ- ing signal peptide, conserved His-Asp-Ser for the catalytic triad, three pairs of cysteines for disulfide bridge configurations, and conserved substrate specificity determination residues. In general, cDNA and putative protein sequences are highly similar between CrylAb-SS and CrylAb-RR strains, except for a few nucleotide and predicted amino acid substitutions, whose function need to be further clarified. Total trypsin and chymotrypsin activities were also similar between CrylAb-SS and CrylAb-RR strains. Transcriptional levels of the trypsin and chymotrypsin genes had numerical difference between Cry 1 Ab-SS and CrylAb-RR strains, but the difference was not statistically significant. Data suggest that the development of CrylAb resistance in D. saccharalis was not significantly as- sociated with these trypsins and chymotrypsins. Results clarified the role of six midgut proteinases and provided a foundation for continuing examination of potential involvement of other midgut proteinases in bt resistance development and other important biochemical processes.

关键词： bt cDNA chymotrypsin enzymatic activity resistance trypsin

Cohort study to assess geographical variation in cholangiocarcinoma treatment in England

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World Journal of Gastrointestinal Oncology 2023年第12期15卷 2077-2092页

作者： Sophie Jose Amy Zalin-Miller craig Knott Lizz Paley Daniela Tataru Helen Morement Mireille b Toledano Shahid A Khan Health Data Analysis Health Data Insight CICCambridge CB215XEUnited Kingdom National Disease Registration Service National Health Service EnglandLondon SE18UGUnited Kingdom Department of Executive AMMF-The Cholangiocarcinoma CharityEssex CM241QWUnited Kingdom MRC Centre for Environment and Health Imperial College LondonLondon SW72BXUnited Kingdom Mohn Centre for Children's Health and Wellbeing Imperial College LondonLondon SW72BXUnited Kingdom Liver Unit Division of Digestive DiseasesImperial College LondonLondon SW72BXUnited Kingdom

bACKGROUND Outcomes for cholangiocarcinoma(CCA)are extremely poor owing to the complexities in diagnosing and managing a rare disease with heterogenous *** curative surgery,which is only an option for a minority of patients diagnosed at an early stage,few systemic therapy options are currently recommended to relieve symptoms and prolong *** insertion to manage disease complications requires highly specialised *** is lacking as to how CCA patients are managed in a real-world setting and whether there is any variation in treatments received by CCA *** To assess geographic variation in treatments received amongst CCA patients in *** Data used in this cohort study were drawn from the National Cancer Registration Dataset(NCRD),Hospital Episode Statistics and the Systemic Anti-Cancer Therapy Dataset.A cohort of 8853 CCA patients diagnosed between 2014-2017 in the National Health Service in England was identified from the *** curative surgery for all patients and systemic therapy and stent insertion for 7751 individuals who did not receive surgery were identified as three end-points of *** probability models assessed variation in each of the three treatment modalities according to Cancer Alliance of residence at diagnosis,and for socio-demographic and clinical characteristics at *** Of 8853 CCA patients,1102(12.4%)received potentially curative *** mean[95%confidence interval(CI)]percentage-point difference from the population average ranged from-3.96(-6.34 to-1.59)%to 3.77(0.54 to 6.99)%across Cancer Alliances in England after adjustment for patient sociodemographic and clinical characteristics,showing statistically significant *** 7751 who did not receive surgery,1542(19.9%)received systemic therapy,with mean[95%CI]percentage-point difference from the population average between-3.84(-8.04 to 0.35)%to 9.28(1.76 to 16.80)%across Cancer Alliances after adjustm

关键词： Cholangiocarcinoma biliary tract cancer Liver cancer Treatment Surgery Systemic therapy Chemotherapy Stent England