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Ex-situ Raman spectroscopy to optimize the manufacturing process for a structural MWNT nanocomposite

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International Journal of Smart and Nano Materials 2012年第4期3卷 309-320页

作者： gregory freihofer Fei Liang Bharathi Mohan Jihua Gou Seetha Raghavan Department of Mechanical Materialsand Aerospace EngineeringUniversity of Central FloridaOrlandoFLUSA

The G and D doublet,an intrinsic Raman feature of multi-walled nanotubes(MWNTs),was monitored in an ex-situ fashion for all intermediate stages of a manufacturing process of a MWNT/polymer *** G peak position and D/G ratios were monitored to characterize the changes in load transfer and disorder,respectively,of the *** in Raman characteristics desired during the manufacturing process for different structural applications are *** are presented that could optimize any manufacturing parameters for pressurized filtration and resin infusion using the G position and D/G integrated intensity *** Raman control techniques could be applied to any intermediate phase of a manufacturing process to develop enhanced novel carbon nanotube composites for structural applications.

关键词： Raman spectroscopy MWNT nanocomposite manufacture ex-situ investigation

Laser sintering of carbon nanotube-reinforced ceramic nanocomposites

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International Journal of Smart and Nano Materials 2011年第4期2卷 219-229页

作者： Yibo Gao Fei Liang gregory freihofer Benxin Wu Bharathi Mohan Seetha Raghavan Jihua Gou Shuyou Li Brian Albee Sandra Whaley Bishnoi Illinois Institute of Technology ChicagoIL 60616USA University of Central Florida OrlandoFL 32816USA Northwestern University EvanstonIL 60208USA

The fabrication of carbon nanotube(CNT)-reinforced ceramic nanocomposites through laser sintering has been rarely studied,and the fabrication feasibility has been rarely *** sintering is a flexible,localized and high-precision process,which can also potentially produce coatings or parts with complicated shapes and/or spatially controlled ***,compared with other technologies laser sintering has its own *** investigations reported in this paper have confirmed the feasibility of fabricating CNT-reinforced ceramic nanocomposites through laser sintering of ceramic nanoparticles and *** studies show that laser sintering can induce the agglomeration of ceramic nanoparticles into a relatively more continuous ceramic phase,and during the sintering process CNTs are well preserved without any obvious quality degradation,and they are also bonded with the ceramic phase after laser sintering.

关键词： laser sintering carbon nanotube reinforcement ceramic nanocomposite

Global weirding at mass extinction horizons

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National Science Review 2024年第1期11卷 10-12页

作者： gregory J.Retallack Department of Earth Sciences University of Oregon

A strong motivation for studying mass extinctions is understanding how current climatic and biodiversity crises will affect creatures living on land such as ourselves. Perhaps the question is: how bad can it get? In that case, terrestrial Permian-Triassic mass extinctions are an irresistible worst-case scenario [1].

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A numerical model to simulate the transient frictional viscoelastic sliding contact

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Friction 2024年第2期12卷 319-339页

作者： Dongze WANG gregory de BOER Anne NEVILLE Ali GHANBARZADEH School of Mechanical Engineering University of LeedsLeeds LS29JTUK

Sliding motion has always been one of the major concerns when it comes to the analysis of viscoelastic contact problems.A new model simulating the transient sliding contact of smooth viscoelastic surfaces is developed in this *** taking the dry contact friction and the coupling between shear tractions and normal pressure into account,the effect of the early partial slip period,which is often neglected in the study of viscoelastic sliding contact problems,is investigated *** with solutions based on the frictionless assumption,the steady-state pressure profile is found to be slightly different under the effect of the partial slip regime,including a lower peak pressure and the shift of the contacting region in the direction opposite to the sliding ***,the time required for the viscoelastic contact to reach its steady state is delayed owing to the partial slip period preceding the global sliding motion.

关键词： contact mechanics frictional sliding viscoelasticity viscoelastic friction

Trends in oxycodone and oxycodone-containing analgesics administration for back pain in emergency departments in the USA(2007–2018)

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World Journal of Emergency Medicine 2024年第3期15卷 169-174页

作者： Jonathan Chabon Jemer Garrido Deanna Schreiber-gregory Jefferson Drapkin Sergey Motov Department of Emergency Medicine Maimonides Medical CenterBrooklyn 11219USA

BACKGROUND:To describe trends in oxycodone and oxycodone-containing analgesic prescribing for the treatment of back pain among adults in emergency departments(EDs) in the USA from 2007 to ***:Data were gathered from the National Hospital Ambulatory Medical Care Survey(NHAMCS) from 2007 to *** study population included individuals of all ages presenting to USA *** NHAMCS reasons for visit and oxycodone drug ID codes were used to isolate patients with back *** main outcome was the proportion of oxycodone and oxycodone-containing analgesics prescribed for back pain in the EDs over the specified time ***:There was a relative decrease in the overall administration of oxycodone for back pain in the EDs by 62.3% from 2007(244,000 visits) to 2018(92,000 visits).The proportion of ED patients prescribed with oxycodone-containing analgesics for back pain increased among patients aged 45 years and older(from 43.8% to 57.6%),female patients(from 54.5% to 62.0%),black patients(from 22.5% to 30.4%),and Hispanic/Latino patients(from 9.4% to 19.6%).Oxycodone/acetaminophen was most prescribed and accounted for 90.2% of all oxycodone-containing analgesics in 2007,with a decrease to 68.5% in *** oxycodone was the second most prescribed medication,accounting for 6.1% in 2007 and 31.5% in ***:The overall number of oxycodone-containing analgesics decreased significantly from 2007 to ***,that number trended upward in 45-year-old and older,female,black,or Hispanic/Latino patients from 2007 to *** total amount of pure oxycodone increased significantly from 2007 to 2008.

关键词： Oxycodone Back pain Emergency department

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一颗自由进动的磁星

科学通报 2024年第25期69卷 3675-3677页

作者：高勇 gregory Desvignes 邵立晶 Max Planck Institute for Gravitational Physics (Albert Einstein Institute) Max Planck Institute for Radio Astronomy 北京大学科维理天文与天体物理研究所中国科学院国家天文台

磁星是一类具有强磁场和长自转周期的年轻中子星.这些天体极其致密,半径约为12 km,但质量却可达太阳的1～2倍.在已知的30颗磁星中,只有少数会偶尔产生射电辐射.磁星转动时,射电束像灯塔一样扫过天空,天文学家正是从这些规律的脉冲信号...

磁星是一类具有强磁场和长自转周期的年轻中子星.这些天体极其致密,半径约为12 km,但质量却可达太阳的1～2倍.在已知的30颗磁星中,只有少数会偶尔产生射电辐射.磁星转动时,射电束像灯塔一样扫过天空,天文学家正是从这些规律的脉冲信号中探索中子星的奥秘. 2018年末,磁星XTE J1810-197在经历了X射线爆发后再次产生射电辐射,结束了其长达十年的射电静默期.通过长时间、高频次的监测,我们在射电偏振信号中发现射电束相对于地球的倾角发生了显著变化,并且这种变化在几个月内逐渐消失[1].我们认为这种变化是由磁星的自由进动引起的,并提出了衰减的进动模型来解释这一观测现象.这一发现不仅帮助我们更深入地理解了磁星的内部结构和辐射几何,而且很可能排除了自由进动作为重复快速射电暴起源的理论模型.

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High Temperature Iron Ethylene Polymerization Catalysts Bearing N,N,N'-2-(1-(2,4-Dibenzhydryl-6-fluorophenylimino)ethyl)-6-(1-(arylphenylimino)ethyl)pyridines

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Chinese Journal of Polymer Science 2024年第2期42卷 188-201,I0007页

作者： Chantsalnyam Bariashir Qiu-Yue Zhang Bayasgalan Ulambayar gregory A.Solan Tong-Ling Liang Wen-Hua Sun Institute of Chemistry and Chemical Technology Mongolian Academy of SciencesUlaanbaatar13330Mongolia Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science Institute of ChemistryChinese Academy of SciencesBeijing100190China Department of Chemistry University of LeicesterUniversity RoadLeicesterLE17RHUK State Key Laboratory for Oxo Synthesis and Selective Oxidation Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou730000China

The N,N,N'-ferrous chloride complexes,[2-{CMeN(2,4-(CHPh)_(2)-6-FC_(6)H_(2))}-6-(CMeNAr)C_(5)H_(3)N]FeCl_(2)(Ar=2,6-Me_(2)C_(6)H_(3) Fe1,2,6-Et_(2)C_(6)H_(3)Fe2,2,6-^(i)Pr_(2)C_(6)H_(3) Fe3,2,4,6-Me_(3)C_(6)H_(2) Fe4 and 2,6-Et_(2)-4-MeC_(6)H_(2) Fe5),each possessing one N-2,4-dibenzhydryl-6-fluorophenyl group,were readily synthesized from their respective unsymmetrical bis(imino)pyridines,*** identification of Fe2 highlighted the variation in the steric properties provided by the dissimilar N-aryl *** pre-treatment with either MAO or MMAO,complexes Fe1-Fe5 all displayed,at an operating temperature of 80℃,high activities for ethylene polymerization with levels falling in the order:Fe4> Fe1> Fe5> Fe2> ***,Fe4/MAO displayed the highest activity of 1.94×10^(7) g_(PE)·mol_(Fe)^(-1)·h^(-1) of the study with only a modest loss in performance at 90℃.Generally,the resulting polyethylenes were highly linear(T_(m) range:122-132℃),narrowly disperse and of low molecular weight(M_(w) range:6.73-46.04kg·mol^(-1)),with the most sterically hindered Fe3 forming the highest molecular weight polymer of the ***-group analysis by ^(1)H-and ^(13)CNMR spectroscopy revealed saturated alkyl(n-propyl and i-propyl) and unsaturated vinyl chain ends indicative of the role of both β-H elimination and chain transfer to aluminum as termination *** comparison with previou sly reported iron precatalysts with similar tridentate ligand skeletons,it is evident that the introduction of a large benzhydryl group in combination with a fluorine as the ortho-substituents of one N-aryl group has the effect of enhancing thermal stability of the iron polymerization catalyst whilst maintaining appreciable polymer molecular weight.

关键词： Iron catalyst Ethylene polymerization Linear polyethylene Fluoride effect Thermal stability

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Integrins and their potential roles in mammalian pregnancy

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Journal of Animal Science and Biotechnology 2024年第1期15卷 1-19页

作者： gregory A.Johnson Robert C.Burghardt Fuller W.Bazer Heewon Seo Joe W.Cain Department of Veterinary Integrative Biosciences School of Veterinary Medicine and Biomedical SciencesTexas A&M UniversityCollege StationTX 77843‑4459USA Department of Animal Science College of Agriculture and Life SciencesTexas A&M UniversityCollege StationTX 77843‑2471USA

Integrins are a highly complex family of receptors that, when expressed on the surface of cells, can mediate reciprocal cell-to-cell and cell-to-extracellular matrix(ECM) interactions leading to assembly of integrin adhesion complexes(IACs) that initiate many signaling functions both at the membrane and deeper within the cytoplasm to coordinate processes including cell adhesion, migration, proliferation, survival, differentiation, and metabolism. All metazoan organisms possess integrins, and it is generally agreed that integrins were associated with the evolution of multicellularity, being essential for the association of cells with their neighbors and surroundings, during embryonic development and many aspects of cellular and molecular biology. Integrins have important roles in many aspects of embryonic development, normal physiology, and disease processes with a multitude of functions discovered and elucidated for integrins that directly influence many areas of biology and medicine, including mammalian pregnancy, in particular implantation of the blastocyst to the uterine wall, subsequent placentation and conceptus(embryo/fetus and associated placental membranes) development. This review provides a succinct overview of integrin structure, ligand binding, and signaling followed with a concise overview of embryonic development, implantation, and early placentation in pigs, sheep, humans, and mice as an example for rodents. A brief timeline of the initial localization of integrin subunits to the uterine luminal epithelium(LE) and conceptus trophoblast is then presented, followed by sequential summaries of integrin expression and function during gestation in pigs, sheep, humans, and rodents. As appropriate for this journal, summaries of integrin expression and function during gestation in pigs and sheep are in depth, whereas summaries for humans and rodents are brief. Because similar models to those illustrated in Fig. 1, 2, 3, 4, 5 and 6 are present throughout the sc

关键词： Humans Implantation Integrins Pigs Pregnancy Rodents Sheep

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PETG:Applications in Modern Medicine

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Engineered Regeneration 2024年第1期5卷 45-55页

作者： Catherine Yan Corinne Kleiner Aaron Tabigue Veer Shah gregory Sacks Darshi Shah Vincent DeStefano Renaissance School of Medicine at Stony Brook University Stony BrookNYUSA Department of Biology Niagara UniversityLewistonNYUSA Stony Brook University Stony BrookNYUSA Department of Mechanical and Industrial Engineering Northeastern UniversityBostonMAUSA

Polyethylene terephthalate glycol,PETG,is a miscible,transparent thermoplastic known to have strong tensile properties,high ductility,as well as resistance to heat and chemical *** may be manufactured in several ways,most notably 3D printing *** such,PETG has emerged as a viable biomaterial for a variety of medical applications such as tissue engineering,dentistry,optometry,vascular health,cardiology,orthopedics,neurology,gynecology,and *** also serves a valuable role in biomedical research and engineering by offering improvements in cell studies,drug carriers,and anti-bacterial *** medical research and innovation utilizing PETG will better characterize its value as an inexpensive and versatile biomaterial.

关键词： Polyethylene terephthalate glycol Tissue Engineering 3D Printing Clinical Applications Biomedical Research