Light beams with a helical phase-front possess orbital angular momentum along their direction of propagation in addition to the spin angular momentum that describes their polarisation.Until recently,it was thought tha...Light beams with a helical phase-front possess orbital angular momentum along their direction of propagation in addition to the spin angular momentum that describes their polarisation.Until recently,it was thought that these two‘rotational’motions of light were largely independent and could not be coupled during light–matter interactions.However,it is now known that interactions with carefully designed complex media can result in spin-to-orbit coupling,where a change of the spin angular momentum will modify the orbital angular momentum and vice versa.In this work,we propose and demonstrate that the birefringence of plasmonic nanostructures can be wielded to transform circularly polarised light into light carrying orbital angular momentum.A device operating at visible wavelengths is designed from a space-variant array of subwavelength plasmonic nano-antennas.Experiment confirms that circularly polarised light transmitted through the device is imbued with orbital angular momentum of 62"(with conversion efficiency of at least 1%).This technology paves the way towards ultrathin orbital angular momentum generators that could be integrated into applications for spectroscopy,nanoscale sensing and classical or quantum communications using integrated photonic devices.展开更多
Background：Intravoxel incoherent motion （IVIM） has the potential to provide both diffusion and perfusion information without an exogenous contrast agent,its application for the brain is promising,however,feasibilit...Background：Intravoxel incoherent motion （IVIM） has the potential to provide both diffusion and perfusion information without an exogenous contrast agent,its application for the brain is promising,however,feasibility studies on this are relatively scarce.The aim of this study is to assess the feasibility of IVIM perfusion in patients with acute ischemic stroke （AIS）.Methods：Patients with suspected AIS were examined by magnetic resonance imaging within 24 h of symptom onset.Fifteen patients （mean age was 68.7 ± 8.0 years） who underwent arterial spin labeling （ASL） and diffusion-weighted imaging （DWI） were identified as having AIS with ischemic penumbra were enrolled,where ischemic penumbra referred to the mismatch areas of ASL and DWI.Eleven different b-values were applied in the biexponential model.Regions of interest were selected in ischemic penumbras and contralateral normal brain regions.Fast apparent diffusion coefficients （ADCs） and ASL cerebral blood flow （CBF） were measured.The paired t-test was applied to compare ASL CBF,fast ADC,and slow ADC measurements between ischemic penumbras and contralateral normal brain regions.Linear regression and Pearson＇s correlation were used to evaluate the correlations among quantitative results.Results：The fast ADCs and ASL CBFs of ischemic penumbras were significantly lower than those of the contralateral normal brain regions （1.93 ± 0.78 μm2/ms vs.3.97 ± 2.49 μm2/ms,P =0.007;13.5 ± 4.5 ml· 100 g-1 ·min-1 vs.29.1 ± 12.7 ml·100 g-1 ·min-1,P ＜ 0.001,respectively）.No significant difference was observed in slow ADCs between ischemic penumbras and contralateral normal brain regions （0.203 ± 0.090 μm2/ms vs.0.198 ± 0.100 μm2/ms,P =0.451）.Compared with contralateral normal brain regions,both CBFs and fast ADCs decreased in ischemic penumbras while slow ADCs remained the same.A significant correlation was detected between fast ADCs and ASL CBFs （r =0.416,P ＜ 0.05）.No statistically significant correlation was obse展开更多
Arterial spin labeling(ASL) is a magnetic resonance imaging technique for measuring tissue perfusion using a freely diffusible intrinsic tracer.As compared with other perfusion techniques,ASL offers several advantages...Arterial spin labeling(ASL) is a magnetic resonance imaging technique for measuring tissue perfusion using a freely diffusible intrinsic tracer.As compared with other perfusion techniques,ASL offers several advantages and is now available for routine clinical practice in many institutions.Its noninvasive nature and ability to quantitatively measure tissue perfusion make ASL ideal for research and clinical studies.Recent technical advances have increased its sensitivity and also extended its potential applications.This review focuses on some basic knowledge of ASL perfusion,emerging techniques and clinical applications in neuroimaging.展开更多
Ulcerative colitis (UC) is a chronic inflammatory bowel disease that may become intractable when treated with conventional medications such as aminosalicylates, corticosteroids, and azathioprine. The herbal medicine Q...Ulcerative colitis (UC) is a chronic inflammatory bowel disease that may become intractable when treated with conventional medications such as aminosalicylates, corticosteroids, and azathioprine. The herbal medicine Qing Dai has traditionally been used in Chinese medicine to treat UC patients, but there is a lack of published data on the efficacy of Qing Dai in UC treatment. We report several cases of patients with intractable UC who take Qing Dai in a retrospective observational study. Furthermore, we explore the mechanisms of action of Qing Dai. Nine patients with active UC who received conventional medications but wished to receive Qing Dai as an alternative medication were included in our analysis. The UC severity level was determined based on the clinical activity index (CAI). Additionally, 5 of the 9 patients were endoscopically evaluated according to the Matts grading system. Each patient received 2 g/d of Qing Dai orally and continued taking other medications for UC as prescribed. Electron spin resonance was applied to explore the mechanisms of action of Qing Dai. After 4 mo of treatment with Qing Dai, the CAI score decreased from 8.3 ± 2.4 to 2.4 ± 3.4 (mean ± SD; P < 0.001). Similarly, the endoscopic Matts grade decreased from 3.4 ± 0.5 to 2.2 ± 0.8 (P = 0.02). Six of 7 patients who were on prednisolone upon enrollment in the study were able to discontinue this corticosteroid. Electron spin resonance revealed that Qing Dai possesses strong hydroxyl radical scavenging activity. Qing Dai showed significant clinical and endoscopic efficacy in patients who failed to respond to conventional medications. Scavenging of hydroxyl radicals appears to be a potential mechanism through which Qing Dai acts, but the significance of the scavenging ability of Qing Dai with respect to the anti-inflammatory effect in UC patients warrants further investigation.展开更多
Structured light with inhomogeneous phase,amplitude,and polarization spatial distributions that represent an infinite-dimensional space of eigenstates for light as the ideal carrier can provide a structured combinatio...Structured light with inhomogeneous phase,amplitude,and polarization spatial distributions that represent an infinite-dimensional space of eigenstates for light as the ideal carrier can provide a structured combination of photonic spin and orbital angular momentum(OAM).Photonic spin angular momentum(SAM)interactions with matter have long been studied,whereas the photonic OAM has only recently been discovered,receiving attention in the past three decades.Although controlling polarization(i.e.,SAM)alone can provide useful information about the media with which the light interacts,light fields carrying both OAM and SAM may provide additional information,permitting new sensing mechanisms and light–matter interactions.We summarize recent developments in controlling photonic angular momentum(AM)using complex structured optical fields.Arbitrarily oriented photonic SAM and OAM states may be generated through careful engineering of the spatial and temporal structures of optical fields.Moreover,we discuss potential applications of specifically engineered photonic AM states in optical tweezers,directional coupling,and optical information transmission and processing.展开更多
The photonic spin Hall effect(SHE)in the reflection and refraction at an interface is very weak because of the weak spin-orbit interaction.Here,we report the observation of a giant photonic SHE in a dielectric-based m...The photonic spin Hall effect(SHE)in the reflection and refraction at an interface is very weak because of the weak spin-orbit interaction.Here,we report the observation of a giant photonic SHE in a dielectric-based metamaterial.The metamaterial is structured to create a coordinate-dependent,geometric Pancharatnam–Berry phase that results in an SHE with a spin-dependent splitting in momentum space.It is unlike the SHE that occurs in real space in the reflection and refraction at an interface,which results from the momentum-dependent gradient of the geometric Rytov–Vladimirskii–Berry phase.We theorize a unified description of the photonic SHE based on the two types of geometric phase gradient,and we experimentally measure the giant spin-dependent shift of the beam centroid produced by the metamaterial at a visible wavelength.Our results suggest that the structured metamaterial offers a potential method of manipulating spin-polarized photons and the orbital angular momentum of light and thus enables applications in spin-controlled nanophotonics.展开更多
For realizing non-contact steering swimming of a capsule robot in curved environment filled with viscous liquid, based on spa- tial orthogonal superposition theorem of alternating magnetic vectors, an innovative physi...For realizing non-contact steering swimming of a capsule robot in curved environment filled with viscous liquid, based on spa- tial orthogonal superposition theorem of alternating magnetic vectors, an innovative physical method is proposed, which em- ploys three-axis orthogonal square Helmholtz coils fed with three phase sine currents to create a universal uniform magnetic spin vector as energy source. According to the antiphase sine current superposition theorem generalized in this paper, an effec- tive control method for successively adjusting the orientation and the rotating direction of the universal magnetic spin vector is proposed. For validating its feasibility and controllability, three-axis Helmholtz coils, power source and an innovative capsule robot prototype were manufactured, experiments were conducted in both spiral pipe and animal intestine. It was demonstrated that the orientation and the rotational direction of the universal uniform-magnetic spin vector can be adjusted successively through digital control and steering swimming of the capsule robot in spiral intestine can be achieved successfully. The breakthrough of the universal rotating uniform-magnetic vector will push forward the development of modern physics and biomedical engineering展开更多
The NUBASE2020 evaluation contains the recommended values of the main nuclear physics properties for all nuclei in their ground and excited,isomeric(T1/2≥100 ns)states.It encompasses all experimental data published i...The NUBASE2020 evaluation contains the recommended values of the main nuclear physics properties for all nuclei in their ground and excited,isomeric(T1/2≥100 ns)states.It encompasses all experimental data published in primary(journal articles)and secondary(mainly laboratory reports and conference proceedings)references,together with the corresponding bibliographical information.In cases where no experimental data were available for a particular nuclide,trends in the behavior of specific properties in neighboring nuclei were examined and estimated values are proposed.Evaluation procedures and policies that were used during the development of this evaluated nuclear data library are presented,together with a detailed table of recommended values and their uncertainties.展开更多
文摘Light beams with a helical phase-front possess orbital angular momentum along their direction of propagation in addition to the spin angular momentum that describes their polarisation.Until recently,it was thought that these two‘rotational’motions of light were largely independent and could not be coupled during light–matter interactions.However,it is now known that interactions with carefully designed complex media can result in spin-to-orbit coupling,where a change of the spin angular momentum will modify the orbital angular momentum and vice versa.In this work,we propose and demonstrate that the birefringence of plasmonic nanostructures can be wielded to transform circularly polarised light into light carrying orbital angular momentum.A device operating at visible wavelengths is designed from a space-variant array of subwavelength plasmonic nano-antennas.Experiment confirms that circularly polarised light transmitted through the device is imbued with orbital angular momentum of 62"(with conversion efficiency of at least 1%).This technology paves the way towards ultrathin orbital angular momentum generators that could be integrated into applications for spectroscopy,nanoscale sensing and classical or quantum communications using integrated photonic devices.
文摘Background：Intravoxel incoherent motion （IVIM） has the potential to provide both diffusion and perfusion information without an exogenous contrast agent,its application for the brain is promising,however,feasibility studies on this are relatively scarce.The aim of this study is to assess the feasibility of IVIM perfusion in patients with acute ischemic stroke （AIS）.Methods：Patients with suspected AIS were examined by magnetic resonance imaging within 24 h of symptom onset.Fifteen patients （mean age was 68.7 ± 8.0 years） who underwent arterial spin labeling （ASL） and diffusion-weighted imaging （DWI） were identified as having AIS with ischemic penumbra were enrolled,where ischemic penumbra referred to the mismatch areas of ASL and DWI.Eleven different b-values were applied in the biexponential model.Regions of interest were selected in ischemic penumbras and contralateral normal brain regions.Fast apparent diffusion coefficients （ADCs） and ASL cerebral blood flow （CBF） were measured.The paired t-test was applied to compare ASL CBF,fast ADC,and slow ADC measurements between ischemic penumbras and contralateral normal brain regions.Linear regression and Pearson＇s correlation were used to evaluate the correlations among quantitative results.Results：The fast ADCs and ASL CBFs of ischemic penumbras were significantly lower than those of the contralateral normal brain regions （1.93 ± 0.78 μm2/ms vs.3.97 ± 2.49 μm2/ms,P =0.007;13.5 ± 4.5 ml· 100 g-1 ·min-1 vs.29.1 ± 12.7 ml·100 g-1 ·min-1,P ＜ 0.001,respectively）.No significant difference was observed in slow ADCs between ischemic penumbras and contralateral normal brain regions （0.203 ± 0.090 μm2/ms vs.0.198 ± 0.100 μm2/ms,P =0.451）.Compared with contralateral normal brain regions,both CBFs and fast ADCs decreased in ischemic penumbras while slow ADCs remained the same.A significant correlation was detected between fast ADCs and ASL CBFs （r =0.416,P ＜ 0.05）.No statistically significant correlation was obse
文摘Arterial spin labeling(ASL) is a magnetic resonance imaging technique for measuring tissue perfusion using a freely diffusible intrinsic tracer.As compared with other perfusion techniques,ASL offers several advantages and is now available for routine clinical practice in many institutions.Its noninvasive nature and ability to quantitatively measure tissue perfusion make ASL ideal for research and clinical studies.Recent technical advances have increased its sensitivity and also extended its potential applications.This review focuses on some basic knowledge of ASL perfusion,emerging techniques and clinical applications in neuroimaging.
文摘Ulcerative colitis (UC) is a chronic inflammatory bowel disease that may become intractable when treated with conventional medications such as aminosalicylates, corticosteroids, and azathioprine. The herbal medicine Qing Dai has traditionally been used in Chinese medicine to treat UC patients, but there is a lack of published data on the efficacy of Qing Dai in UC treatment. We report several cases of patients with intractable UC who take Qing Dai in a retrospective observational study. Furthermore, we explore the mechanisms of action of Qing Dai. Nine patients with active UC who received conventional medications but wished to receive Qing Dai as an alternative medication were included in our analysis. The UC severity level was determined based on the clinical activity index (CAI). Additionally, 5 of the 9 patients were endoscopically evaluated according to the Matts grading system. Each patient received 2 g/d of Qing Dai orally and continued taking other medications for UC as prescribed. Electron spin resonance was applied to explore the mechanisms of action of Qing Dai. After 4 mo of treatment with Qing Dai, the CAI score decreased from 8.3 ± 2.4 to 2.4 ± 3.4 (mean ± SD; P < 0.001). Similarly, the endoscopic Matts grade decreased from 3.4 ± 0.5 to 2.2 ± 0.8 (P = 0.02). Six of 7 patients who were on prednisolone upon enrollment in the study were able to discontinue this corticosteroid. Electron spin resonance revealed that Qing Dai possesses strong hydroxyl radical scavenging activity. Qing Dai showed significant clinical and endoscopic efficacy in patients who failed to respond to conventional medications. Scavenging of hydroxyl radicals appears to be a potential mechanism through which Qing Dai acts, but the significance of the scavenging ability of Qing Dai with respect to the anti-inflammatory effect in UC patients warrants further investigation.
基金supported by the National Natural Science Foundation of China(Nos.92050202,61805142,and 61875245)Shanghai Science and Technology Committee(No.19060502500)Shanghai Natural Science Foundation(No.20ZR1437600).
文摘Structured light with inhomogeneous phase,amplitude,and polarization spatial distributions that represent an infinite-dimensional space of eigenstates for light as the ideal carrier can provide a structured combination of photonic spin and orbital angular momentum(OAM).Photonic spin angular momentum(SAM)interactions with matter have long been studied,whereas the photonic OAM has only recently been discovered,receiving attention in the past three decades.Although controlling polarization(i.e.,SAM)alone can provide useful information about the media with which the light interacts,light fields carrying both OAM and SAM may provide additional information,permitting new sensing mechanisms and light–matter interactions.We summarize recent developments in controlling photonic angular momentum(AM)using complex structured optical fields.Arbitrarily oriented photonic SAM and OAM states may be generated through careful engineering of the spatial and temporal structures of optical fields.Moreover,we discuss potential applications of specifically engineered photonic AM states in optical tweezers,directional coupling,and optical information transmission and processing.
基金This research was partially supported by the National Natural Science Foundation of China(Grants No.11274106,No.11474089 and No.11447010)the China Postdoctoral Science Foundation(Grant No.2014M562198)+1 种基金the Scientific Research Fund of Hunan Provincial Education Department of China(Grant No.13B003)the Natural Science Foundation of Hunan Province(Grant No.2015JJ3026).
文摘The photonic spin Hall effect(SHE)in the reflection and refraction at an interface is very weak because of the weak spin-orbit interaction.Here,we report the observation of a giant photonic SHE in a dielectric-based metamaterial.The metamaterial is structured to create a coordinate-dependent,geometric Pancharatnam–Berry phase that results in an SHE with a spin-dependent splitting in momentum space.It is unlike the SHE that occurs in real space in the reflection and refraction at an interface,which results from the momentum-dependent gradient of the geometric Rytov–Vladimirskii–Berry phase.We theorize a unified description of the photonic SHE based on the two types of geometric phase gradient,and we experimentally measure the giant spin-dependent shift of the beam centroid produced by the metamaterial at a visible wavelength.Our results suggest that the structured metamaterial offers a potential method of manipulating spin-polarized photons and the orbital angular momentum of light and thus enables applications in spin-controlled nanophotonics.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60875064,61175102,and 51277018)
文摘For realizing non-contact steering swimming of a capsule robot in curved environment filled with viscous liquid, based on spa- tial orthogonal superposition theorem of alternating magnetic vectors, an innovative physical method is proposed, which em- ploys three-axis orthogonal square Helmholtz coils fed with three phase sine currents to create a universal uniform magnetic spin vector as energy source. According to the antiphase sine current superposition theorem generalized in this paper, an effec- tive control method for successively adjusting the orientation and the rotating direction of the universal magnetic spin vector is proposed. For validating its feasibility and controllability, three-axis Helmholtz coils, power source and an innovative capsule robot prototype were manufactured, experiments were conducted in both spiral pipe and animal intestine. It was demonstrated that the orientation and the rotational direction of the universal uniform-magnetic spin vector can be adjusted successively through digital control and steering swimming of the capsule robot in spiral intestine can be achieved successfully. The breakthrough of the universal rotating uniform-magnetic vector will push forward the development of modern physics and biomedical engineering
基金This work was supported by the U.S.Department of Energy,Office of Science,Office of Nuclear Physics,under Contract No.DE-AC02-06CH11357(ANL)in part by the National Key Research and Development Program of China(Grant No.2016YFA0400504)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(CAS,Grant No.XDB34000000)(IMP)W.J.Huang acknowledges the financial support by the Max-Planck-Society.S.Naimi acknowledges the support of the RIKEN Pioneering Project Funding.
文摘The NUBASE2020 evaluation contains the recommended values of the main nuclear physics properties for all nuclei in their ground and excited,isomeric(T1/2≥100 ns)states.It encompasses all experimental data published in primary(journal articles)and secondary(mainly laboratory reports and conference proceedings)references,together with the corresponding bibliographical information.In cases where no experimental data were available for a particular nuclide,trends in the behavior of specific properties in neighboring nuclei were examined and estimated values are proposed.Evaluation procedures and policies that were used during the development of this evaluated nuclear data library are presented,together with a detailed table of recommended values and their uncertainties.
