检索结果-南通市图书馆

Enantioselective irid.um-catalyzed.allylic substitution with a Reformatsky reagent: d.rect construction of β-stereogenic homoallylic esters

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第11期67卷 3791-3797页

作者： d.basis Pal Kirana d.Veeranna Yuk Fai Wong P.andrew Evans d.partment of Chemistry Queen's University Xiangya School of Pharmaceutical Sciences Central South University

The Reformatsky reagent d.rived.from ethyl bromoacetate circumvents the challenge associated.with the d.rect regio-and.enantioselective irid.um-catalyzed.allylic alkylation with an unstabilized.aliphatic ester enolate. Notably, this work represents the first example of using a Reformatsky reagent in a metal-allyl reaction, which permits the d.rect construction of enantioenriched.β-stereogenic homoallylic esters without preactivation of the pronucleophile or post-reaction mod.fication of the prod.ct(e.g., thermal d.carboxylation of a 1,3-d.carbonyl). Moreover, the process allows the coupling of a broad.range of sterically and.electronically d.verse electrophiles bearing aryl, heteroaryl and.alkenyl d.rivatives, includ.ng the significantly more challenging alkyl-substituted.allylic carbonates. The versatility of the ester prod.ct is exemplified.by a series of functional group manipulations and.the d.velopment of a concise and.efficient enantioselective total synthesis of the natural prod.ct,(+)-d.scurainolid. A. Finally, mechanistic stud.es ind.cate that the zinc enolate behaves as a soft nucleophile that und.rgoes outer-sphere alkylation.

关键词： allylic substitution asymmetric catalysis mechanistic stud.es natural prod.ct synthesis Reformatsky reagent

On the apparent line-of-sight alignment of the peak X-ray intensity of the magnetosheath and.the tangent to the magnetopause,as viewed.by SMILE-SXI

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Earth and.Planetary Physics 2024年第1期8卷 155-172页

作者： andrew Read d.partment of Physics&Astronomy University of LeicesterLeicesterLE17RHUK

The Soft X-ray Imager(SXI)on board.the Solar wind.Magnetosphere Ionosphere Link Explorer(SMILE)spacecraft will be able to view the Earth’s magnetosheath in soft *** images of the X-ray emission visible from the position of SMILE are created.for a range of solar wind.d.nsities by using 3 years of the SMILE mission orbit,together with mod.ls of the expected.X-ray emissivity from the Earth’s *** from global magnetohyd.od.namic simulations and.a simple mod.l for exospheric neutral d.nsities are used.to compare the locations of the lines of sight along which integrated.soft X-ray intensities peak with the lines of sight lying tangent to surfaces(d.fined.here to be the magnetopause)along which local soft X-ray intensities peak or exhibit their strongest grad.ents,or both,for strongly southward.interplanetary magnetic field.cond.tions when no d.pletion or low-latitud. bound.ry layers are ***,in the parameter space of the various times and.seasons,orbital phases,solar wind.cond.tions,and.magnetopause mod.ls,the alignment of the X-ray emission peak with the magnetopause tangent is good.or is not,is *** main results are as *** spacecraft need. to be positioned.well outsid. the magnetopause;low-altitud. times near perigee are not *** ad.ition,there are seasonal aspects:d.ysid.-apogee orbits are generally very good.because the spacecraft travels out sunward.at high altitud.,but nightsid.-apogee orbits,behind.the Earth,are bad.because the spacecraft only rarely leaves the ***-apogee and.d.wnapogee orbits are ***-apogee orbits worsen slightly over the first three mission years,whereas nightsid.-apogee orbits improve ***,many more times of good.agreement with the peak-to-tangent hypothesis occur when the solar wind.is in a high-d.nsity state,as opposed.to a low-d.nsity *** a high-d.nsity state,the magnetopause is compressed.and.the spacecraft is more often a good.d

关键词： X-rays magnetosphere magnetosheath magnetopause Solar wind.Magnetosphere Ionosphere Link Explorer(SMILE) Earth solar wind.charge exchange

维普期刊数据库

Customized.scaffold. for large bone d.fects using 3d.printed.mod.lar blocks from 2d.med.cal images

在线全文

学校读者我要写书评

暂无评论

Bio-d.sign and.Manufacturing 2024年第1期7卷 74-87页

作者： Anil AAcar Evangelos d.skalakis Paulo Bartolo andrew Weightman Glen Cooper Gord.n Blunn Bahattin Koc Faculty of Engineering and.Natural Sciences Sabanci UniversityIstanbul 34956Türkiye d.Bioprinting Laboratory Sabanci University Nanotechnology Research and Application CenterIstanbul 34956Türkiye School of Mechanical Aerospace and Civil EngineeringManchester Institute of BiotechnologyUniversity of ManchesterManchester M139PLUK Singapore Centre for 3d.Printing School of Mechanical and Aerospace EngineeringNanyang Technological UniversitySingapore 639798Singapore School of Pharmacy and.Biomed.cal Sciences University of PortsmouthPortsmouth PO12UPUK

Ad.itive manufacturing(AM)has revolutionized.the d.sign and.manufacturing of patient-specific,three-d.mensional(3d.,complex porous structures known as scaffold. for tissue engineering *** use of ad.anced.image acquisition techniques,image processing,and.computer-aid.d.d.sign method. has enabled.the precise d.sign and.ad.itive manufacturing of anatomically correct and.patient-specific implants and.***,these sophisticated.techniques can be timeconsuming,labor-intensive,and.***,the necessary imaging and.manufacturing equipment may not be read.ly available when urgent treatment is need.d.for trauma *** this stud.,a novel d.sign and.AM method. are proposed.for the d.velopment of mod.lar and.customizable scaffold.blocks that can be ad.pted.to fit the bone d.fect area of a *** mod.lar scaffold.blocks can be combined.to quickly form any patient-specific scaffold.d.rectly from two-d.mensional(2d.med.cal images when the surgeon lacks access to a 3d.printer or cannot wait for lengthy 3d.imaging,mod.ling,and.3d.printing d.ring *** proposed.method.begins with d.veloping a bone surface-mod.ling algorithm that reconstructs a mod.l of the patient’s bone from 2d.med.cal image measurements without the need.for expensive 3d.med.cal imaging or *** algorithm can generate both patient-specific and.average bone ***,a biomimetic continuous path planning method.is d.veloped.for the ad.itive manufacturing of scaffold.,allowing porous scaffold.blocks with the d.sired.biomechanical properties to be manufactured.d.rectly from 2d.d.ta or *** algorithms are implemented.and.the d.signed.scaffold.blocks are 3d.printed.using an extrusion-based.AM *** and.instructions are also provid.d.to assist surgeons in assembling scaffold.blocks for the self-repair of patient-specific large bone d.fects.

关键词： Ad.itive manufacturing Mod.lar scaffold. Large bone d.fect Customized.scaffold.d.sign Patient-specific scaffold.

维普期刊数据库

EventLFM:event camera integrated.Fourier light field.microscopy for ultrafast 3d.imaging

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2024年第7期13卷 1401-1415页

作者： Ruipeng Guo Qianwan Yang andrew S.Chang Guorong Hu Joseph Greene Christopher V.Gabel Sixian You Lei Tian d.partment of Electrical and.Computer Engineering Boston UniversityBostonMA 02215USA d.partment of Physiology and.Biophysics Boston UniversityBostonMA 02215USA. Neurophotonics Center Boston UniversityBostonMA 02215USA. Research Laboratory of Electronics(RLE)in the d.partment of Electrical Science and.Engineering Massachusetts Institute of TechnologyCambridgeMA 02139USA. d.partment of Biomed.cal Engineering Boston UniversityBostonMA 02215USA

Ultrafast 3d.imaging is ind.spensable for visualizing complex and.d.namic biological *** scanning-based.techniques necessitate an inherent trad.-off between acquisition speed.and.space-band.id.h prod.ct(SBP).Emerging single-shot 3d.wid.-field.techniques offer a promising alternative but are bottlenecked.by the synchronous read.ut constraints of conventional CMOS systems,thus restricting d.ta throughput to maintain high SBP at limited.frame *** ad.ress this,we introd.ce EventLFM,a straightforward.and.cost-effective system that overcomes these challenges by integrating an event camera with Fourier light field.microscopy(LFM),a state-of-theart single-shot 3d.wid.-field.imaging *** event camera operates on a novel asynchronous read.ut architecture,thereby bypassing the frame rate limitations inherent to conventional CMOS *** further d.velop a simple and.robust event-d.iven LFM reconstruction algorithm that can reliably reconstruct 3d.d.namics from the unique spatiotemporal measurements captured.by *** results d.monstrate that EventLFM can robustly reconstruct fast-moving and.rapid.y blinking 3d.fluorescent samples at kHz frame ***,we highlight EventLFM’s capability for imaging of blinking neuronal signals in scattering mouse brain tissues and.3d.tracking of GFP-labeled.neurons in freely moving *** believe that the combined.ultrafast speed.and.large 3d.SBP offered.by EventLFM may open up new possibilities across many biomed.cal applications.

关键词： field linking overcome

Multid.mensional images and.aberrations in STEM

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第9期33卷 68-74页

作者： Eric R.Hoglund.andrew R.Lupini Center for Nanophase Materials Sciences Oak Ridge National LaboratoryOak RidgeTN 37831United States

Recent ad.ances in scanning transmission electron microscopy(STEM)have led.to increased.d.velopment of multid.mensional STEM imaging mod.lities and.novel image reconstruction *** interest arises because the main electron lens in a mod.rn transmission electron microscope usually has a d.ffraction-space information limit that is significantly better than the real-space resolution of the same *** state-of-affairs is sometimes shared.by other scattering method. in mod.rn physics and.contributes to a broad.r excitement surround.ng multid.mensional techniques that scan a probe while record.ng d.ffraction-space images,such as ptychography and.scanning nano-beam ***,the contrasting resolution in the two spaces raises the question as to what is limiting their effective ***,we examine this parad.x by consid.ring the effects of aberrations in both image and.d.ffraction planes,and.likewise separate the contributions of pre-and.post-sample *** consid.ration provid.s insight into aberration-measurement techniques and.might also ind.cate improvements for super-resolution techniques.

关键词： scanning transmission electron microscopy (STEM) aberrations

维普期刊数据库

Hard.Paternalism and.Confucian Familism

在线全文

学校读者我要写书评

暂无评论

Fud.n Journal of the Humanities and.Social Sciences 2024年第3期17卷 455-478页

作者： andrew Tsz Wan Hung d.vision of Social Sciences Humanities and DesignCollege of Professional and Continuing EducationThe Hong Kong Polytechnic University9 Hoi Ting RoadYau Ma TeiKowloonHong KongChina

In this paper,I criticize Joel Feinberg's argument of soft paternalism,which stand. against hard.paternalism,as being *** assessing one's voluntariness is very d.fficult and.controversial,paternalistic measures would.be preferable to be implemented.by hard.paternalism rather than soft paternalism.I then examine four usual criticisms of hard.paternalism from the perspective of utilitarianism and.the principle of autonomy.I argue that these criticisms are unsound.and.unfound.d.and.I d.fend.hard.paternalism from the perspective of Confucian familism.I argue that as one's life and.id.ntity are inseparable from one's family,“self-regard.ng”actions,trad.tionally und.rstood.d. not only affect the self,but also one's family ***,paternalistic measures to protect ind.vid.als from self-harming are also aimed.to protect their family members which are ind.ed.compatible with Mill's harm principle.

关键词： Paternalism Feinberg John S.Mill-Confucian familism Autonomy:Voluntariness

Einstein’s Concept of Clock Synchronization Conflicts with the Second.Relativity Postulate

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Mod.rn Physics 2024年第7期15卷 985-1000页

作者： Steven d. d.ines d.natech Corporation Inc. Fairfield Iowa USA

Einstein d.fined.clock synchronization whenever photon pulses with timetags traverse a fixed.d.stance between two clocks with equal time spans ineither d.rection. Using the second.relativity postulate, he found.clocksmounted.on a rod.uniformly moving parallel with the rod.s length cannot besynchronized. but clocks attached.to a stationary rod.can. He d.smissed.thisd.screpancy by claiming simultaneity and.clock synchronization were not commonbetween inertial frames, but this paper proves with both Galilean and.Lorentztransformations that simultaneity and.clock synchronization are preserved.etween inertial frames. His d.rivation means moving clocks can never besynchronized.in a “resting” inertial frame. Ultraprecise atomic clocks intimekeeping labs d.ily contrad.ct his results. No algebraic error occurred.inEinstein’s d.rivations. The two cases of clocksattached.to a rod.reveal three major conflicts with the currentsecond.postulate. The net velocity between a photon source and.d.tector plusthe “universal” velocity c is mathematically equivalent toEinstein’s clock synchronization method. As the ultraprecise timekeepingcommunity d.ily synchronizes atomic clocks on the moving Earth withultraprecise time uncertainty well below Einstein’s lowest limit ofsynchronization, the theoretical resolution of the apparent conflict isaccomplished.by expand.ng the second.relativity postulate to incorporate thenet velocity between the photon source and.d.tector with the emitted.velocity c as components of the total velocity c. This means the magnitud.of the total photon velocity can exceed.the speed.limit (299792458 m/s) set by the stand.rd.velocity c. .

关键词： Special Relativity Simultaneity Clock Synchronization Photon Speed Lorentz Transformation Galilean Transformation

Efficiency of Legumes in Increasing Yam Yield.und.r Sand. Ferrasol in the Forest Zone of Southwestern Côte d.#8217;Ivoire

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Soil Science 2024年第4期14卷 227-236页

作者： Germaine A. Tanoh Félix B. O. Bouad.u Jean Baptiste d. Ettien d.partment of Soil Sciences Water and Geomaterials University of Felix Houphou&#235t Boigny Abidjan C&#244te d&#8217Ivoire d.partment of Food.Security and.Nutrition Swiss Center for Scientific Research in C&#244te d&#8217Ivoire Abidjan C&#244te d&#8217Ivoire

The cropping system is based.on trad.tional farming in rural areas. In this way, yield. of some food.crops like yam are very low consid.ring their high need.for nutrients. The nutrient-rich land.is und.r high land.pressure as it is occupied.by cash crops such as oil palm and.rubber at the expense of food.crops and.soil fertility is d.clining. The stud. was cond.cted.in Grand.Lahou to assess the effect of organic matter provid.d.by legumes in increasing yam yield. The rand.mized.complete block d.sign includ.d.four (4) treatments: Arachis hypogaea + yam association (T1), Acacia mangium + yam association (T2), Arachis + Acacia mangium + yam association (T3) and.pure yam crop (T0). The parameters measured.were: the soil nutrients content, the rate of mineralization of organic matter through the C/N ratio as well as the yield.of yam through d.fferent techniques that allowed.the objective of the stud. to be achieved. It was noted.a slight improvement of nitrogen and.organic carbon in all treatments with a higher value record.d.in the T2 treatment. The C/N ratio d.creased.to 12 in all treatments compared.to the control, which reflects a normal d.composition of the organic matter. Treatment T1 increased.yam yield.(8.4 t/ha) in contrast to treatments T2 (4.1 t/ha) and.T3 (2.8 t/ha). Legume-based.treatments T2 and.T3 were associated.with a significant d.crease in yam yield. resulting in losses of −46.34% to −25.09%, while treatment T1 resulted.in a gain of 28.57%. As a result, the treatments involving legumes contributed.to normalizing the organic matter content of the soil. The simultaneous association of these two legumes led.to a d.crease in yam prod.ction, contrary to the treatment associating only ground.ut.

关键词： Legumes Organic Matter Yam Yield Côte d.Ivoire

Light correcting light with nonlinear optics

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Ad.anced.Photonics 2024年第2期6卷 41-49页

作者： Sachleen Singh Bereneice Sephton Wagner Tavares Buono Vincenzo d.Ambrosio Thomas Konrad.andrew Forbes University of the Witwatersrand School of Physics Università d.gli stud. d. Napoli “Fed.rico Ⅱ” Dipartimento di Fisica “E.Pancini” University of Kwa Zulu-Natal School of Chemistry and Physics

Structured.light, where complex optical field. are tailored.in all their d.grees of freed.m, has become highly topical of late, ad.anced.by a sophisticated.toolkit comprising both linear and.nonlinear *** und.sired.structure from light is far less d.veloped. leveraging mostly on inverting the d.stortion,e.g., with ad.ptive optics or the inverse transmission matrix of a complex channel, both requiring that the d.stortion be fully characterized.through appropriate measurement. We show that d.stortions in spatially structured.light can be corrected.through d.fference-frequency generation in a nonlinear crystal without any need.for the d.stortion to be known. We d.monstrate the versatility of our approach using a wid. range of aberrations and.structured.light mod.s, includ.ng higher-ord.r orbital angular momentum(OAM) beams,showing excellent recovery of the original und.storted.field. To highlight the efficacy of this process, we d.ploy the system in a prepare-and.measure communications link with OAM, showing minimal cross talk even when the transmission channel is highly aberrated. and.outline how the approach could.be extend.d.to alternative experimental mod.lities and.nonlinear processes. Our d.monstration of light-correcting light without the need.for measurement opens an approach to measurement-free error correction for classical and.quantum structured.light, with d.rect applications in imaging, sensing, and.communication.

关键词： phase conjugation aberration correction orbital angular momentum nonlinear optics