Linearized approximations of reflection and transmission coefficients set a foundation for amplitude versus offset（AVO） analysis and inversion in exploration geophysics.However,the weak properties contrast hypothesi...Linearized approximations of reflection and transmission coefficients set a foundation for amplitude versus offset（AVO） analysis and inversion in exploration geophysics.However,the weak properties contrast hypothesis of those linearized approximate equations leads to big errors when the two media across the interface vary dramatically.To extend the application of AVO analysis and inversion to high contrast between the properties of the two layers,we derive a novel nonlinearized high-contrast approximation of the PP-wave reflection coefficient,which establishes the direct relationship between PPwave reflection coefficient and P-wave velocities,S-wave velocities and densities across the interface.（A PP wave is a reflected compressional wave from an incident compressional wave（P-wave）.） This novel approximation is derived from the exact reflection coefficient equation with Taylor expansion for the incident angle.Model tests demonstrate that,compared with the reflection coefficients of the linearized approximations,the reflection coefficients of the novel nonlinearized approximate equation agree with those of the exact PP equation better for a high contrast interface with a moderate incident angle.Furthermore,we introduce a nonlinear direct inversion method utilizing the novel reflection coefficient equation as forward solver,to implement the direct inversion for the six parameters including P-wave velocities,S-wave velocities,and densities in the upper and lower layers across the interface.This nonlinear inversion algorithm is able to estimate the inverse of the nonlinear function in terms of model parameters directly rather than in a conventional optimization way.Three examples verified the feasibility and suitability of this novel approximation for a high contrast interface,and we still could estimate the six parameters across the interface reasonably when the parameters in both media across the interface vary about 50%.展开更多
The plasma mirror system was installed on the 1 PW laser beamline of Shanghai Superintense Ultrafast Laser Facility[SULF]for enhancing the temporal contrast of the laser pulse.About 2 orders of magnitude improvement o...The plasma mirror system was installed on the 1 PW laser beamline of Shanghai Superintense Ultrafast Laser Facility[SULF]for enhancing the temporal contrast of the laser pulse.About 2 orders of magnitude improvement on pulse contrast was measured on picosecond and nanosecond time scales.The experiments show that high-contrast laser pulses can significantly improve the cutoff energy and quantity of proton beams.Then different target distributions are assumed in particles in cell simulations,which can qualitatively assume the expansion of nanometer-scale foil.The high-contrast laser enables the SULF-1PW beamline to generally be of benefit for many potential applications.展开更多
Developing dual-state luminophores(DSLs)with strong fluorescence in both the monomer and aggregate states is urgently needed but remains a huge challenge because most current luminophores are either aggregation-induce...Developing dual-state luminophores(DSLs)with strong fluorescence in both the monomer and aggregate states is urgently needed but remains a huge challenge because most current luminophores are either aggregation-induced emission or aggregation-caused quenching molecules.Moreover,limited by the structural conservation of the few existing DSLs,there are not enough response sites that can be used to customize various activatable fluorescent probes for specific molecular imaging.Herein,we engineered a general integration strategy for the fabrication of such DSLs with excellent photophysical properties.The DSLs,with their tunable spectra,a large Stokes shift(>170 nm),and achievable near-infrared(NIR)emission,show great potential for high-contrast imaging.Importantly,DSLs can be used as a universal platform for probe customization due to their activatable fluorescence through protection-deprotection of the phenolic hydroxyl group.Based on this,an NIR fluorescent probe DSL-Gal was developed for sensing of β-galactosidase in solutions,senescent cells,and liver metastases with high contrast,further confirming the superiority and universal feasibility of DSLs in probe design.The integration strategy may provide a novel approach for the generation of other DSLs and have great potential applications in bioimaging.展开更多
High-contrast imaging coronagraphs, used for the detection of exoplanets, have always adopted passive coronagraph optical components. It is therefore impossible to actively optimize the coronagraphs to achieve their b...High-contrast imaging coronagraphs, used for the detection of exoplanets, have always adopted passive coronagraph optical components. It is therefore impossible to actively optimize the coronagraphs to achieve their best performance. To solve this problem, we propose a novel high-contrast imaging coronagraph which combines a liquid crystal array （LCA） for active pupil apodization and a deformable mirror （DM） for phase correction. The LCA we use is an amplitude-only spatial light mod- ulator. The LCA is well calibrated and compensates for its amplitude non-uniformity and nonlinear intensity responsivity. We measured the imaging contrasts of the coron- agraph system with the LCA only and without the DM deployed. Imaging contrasts of 10-4 and 10-5 can be reached at an inner working angular distance of 2.5 and 5A/D, respectively. A simulation shows that the phase errors on the coronagraph pupil limit the contrast performance. The contrast could be further improved if a DM is deployed to correct the phase errors induced by the LCA and coronagraph optics.展开更多
We propose a novel scheme of optical confinement for atoms by using a concave grating reflector.The two-dimension grating structure with a concave surface shape exhibits strong focusing ability under radially polarize...We propose a novel scheme of optical confinement for atoms by using a concave grating reflector.The two-dimension grating structure with a concave surface shape exhibits strong focusing ability under radially polarized illumination.Especially,the light intensity at the focal point is about 100 times higher than that of the incident light.Such a focusing optical field reflected from the curved grating structure can provide a deep potential to trap cold atoms.We discuss the feasibility of the structure serving as an optical dipole trap.Our results are as follows.（i） Van der Waals attraction potential to the surface of the structure has a low effect on trapped atoms,（ⅱ） The maximum trapping potential is ~1.14 mK in the optical trap,which is high enough to trap cold ^87Rb atoms from a standard magneto-optical trap with a temperature of 120 μK,and the maximum photon scattering rate is lower than 1/s.（ⅲ） Such a microtrap array can also manipulate and control cold molecules,or microscopic particles.展开更多
High-contrast imaging provided by a coronagraph is critical for the direction imaging of the Earth-like planet orbiting its bright parent star.A major limitation for such direct imaging is the speckle noise that is in...High-contrast imaging provided by a coronagraph is critical for the direction imaging of the Earth-like planet orbiting its bright parent star.A major limitation for such direct imaging is the speckle noise that is induced from the wave-front error of an optical system.We derive an algorithm for the wave-front measurement directly from 3 focal plane images.The 3 images are achieved through a deformable mirror to provide specific phases for the optics system.We introduce an extra amplitude modulation on one deformable mirror configuration to create an uncorrelated wave-front,which is a critical procedure for wave-front sensing.The simulation shows that the reconstructed wave-front is consistent with the original wave-front theoretically,which indicates that such an algorithm is a promising technique for the wave-front measurement for the high-contrast imaging.展开更多
In this paper is considered the reproduction process of high-contrast objects in systems with limited dynamic range.There was proposed an algorithm of forming of high-contrast digital original,
This paper proposed a novel broadband filter using multi-layer sub-wavelength high-contrast grating （HCG） structure. This filter has wide bandwidth and good sideband suppression. We simulated and analyzed the effect...This paper proposed a novel broadband filter using multi-layer sub-wavelength high-contrast grating （HCG） structure. This filter has wide bandwidth and good sideband suppression. We simulated and analyzed the effects of different numbers of layers and different grating indexes on filtering performance of the broadband filter. According to the simulated results, we designed a multi- layer HCG broadband filter, which has bandwidth of 843 nm and center wavelength of 1550 nm.展开更多
In this paper we use the Generalized Multiscale Finite Element Method(GMsFEM)framework,introduced in[26],in order to solve nonlinear elliptic equations with high-contrast coefficients.The proposed solution method invo...In this paper we use the Generalized Multiscale Finite Element Method(GMsFEM)framework,introduced in[26],in order to solve nonlinear elliptic equations with high-contrast coefficients.The proposed solution method involves linearizing the equation so that coarse-grid quantities of previous solution iterates can be regarded as auxiliary parameters within the problem formulation.With this convention,we systematically construct respective coarse solution spaces that lend themselves to either continuous Galerkin(CG)or discontinuous Galerkin(DG)global formulations.Here,we use Symmetric Interior Penalty Discontinuous Galerkin approach.Both methods yield a predictable error decline that depends on the respective coarse space dimension,and we illustrate the effectiveness of the CG and DG formulations by offering a variety of numerical examples.展开更多
Novel construction of a resonant-cavity-enhanced photodetector(RCE-PD) with monolithic high-contrast grating(HCG)is proposed to overcome the difficulty of fabricating a high reflective mirror of RCE-PD at 1 550 nm. In...Novel construction of a resonant-cavity-enhanced photodetector(RCE-PD) with monolithic high-contrast grating(HCG)is proposed to overcome the difficulty of fabricating a high reflective mirror of RCE-PD at 1 550 nm. In this structure,HCG serves as the top mirror of the RCE-PD, whereas InGaAs serves as a sacrificial layer to achieve monolithic integration.During the bandwidth optimization, the ratio of the thickness of the total intrinsic region and the absorption layer is introduced to realize the simultaneous optimization of the thickness of spacing layers and absorption layer. After structural optimization, the quantum efficiency of the device with diameter of 20 μm is 82% at 1 550 nm, and the 3-dB bandwidth is 34 GHz at a bias of 3 V.展开更多
High-contrast mechanochromic(MC)materials are prominent candidates for sensor,security,and memory applications;however,the development of materials with a large luminescence change(Δλem>100 nm)under external stim...High-contrast mechanochromic(MC)materials are prominent candidates for sensor,security,and memory applications;however,the development of materials with a large luminescence change(Δλem>100 nm)under external stimuli is challenging.Considering that polymorphic molecules usually exhibit reversible mechanochromism,polymorph prediction is adopted for thefirst time to guide the design of high-contrastMC materials in this study.We designed and synthesized a series of donor–π–acceptor pyran derivatives bearing different electron donors and acceptors as model systems.The polymorph prediction indicated that 4-dicyanomethylene-2,6-distyryl-4H-pyran and 4H-pyran-4-one derivatives had the potential to crystallize in both monomer andπ-dimer aggregates,while barbituric acid-based compound tended to pack tightly in all aggregated states.The experimental results agreed well with the prediction that the derivatives potentially possessing both monomer andπ-dimer aggregate structures exhibit excellent MC behavior,whereas the fluorescence difference for the barbituric acid-based compounds is minimal.Moreover,a compound with an excellent fluorescence difference of three colors during reversible mechanochromism was chosen as the candidate for an optical recording material and security ink.This work proposes an effective method to guide the design of stimuli-responsive materials,which may open promising avenues for the development of high-contrast MC molecules.展开更多
To achieve the enhancement and manipulation of light absorption in graphene within the visible and near infrared regions, a design consists of high-contrast gratings and two evanescently coupled slabs with graphene mo...To achieve the enhancement and manipulation of light absorption in graphene within the visible and near infrared regions, a design consists of high-contrast gratings and two evanescently coupled slabs with graphene monolayer is demonstrated. The operation principle and design process of the proposed structure are analyzed using the coupled mode theory, which is confirmed by the rigorous coupled wave analysis. It is proved that the absorptance of graphene monolayer can be greatly enhanced to unity. The thickness of grating and slab layers can significantly change the line width and resonant mode position in the absorption spectra. Furthermore, high tunability in amplitude and bandwidth of the absorption spectra can be achieved by controlling the structural parameters of the hybrid structure. The proposed devices could be efficiently exploited as tunable and selective absorbers, and could be allowed to realize other two-dimensional materials-based selective photo-detectors.展开更多
AIM：To investigate quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy（Trans PRK）in high myopia.METHODS：In a prospective interventional case-series,30 eyes with...AIM：To investigate quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy（Trans PRK）in high myopia.METHODS：In a prospective interventional case-series,30 eyes with high myopia（-6.00 to-8.75 D）with（up to-3.00 D）or without astigmatism were enrolled from Bina Eye Hospital,Tehran,Iran. One-step Trans PRK was performed with aberration-free aspherical optimized profile and SCHWIND AMARIS 500 laser. One-year follow-up results for refraction,visual acuities,vector analysis,ocular wavefront（OWF）and corneal wave-front（CWF）higher order aberrations（HOA）,contrast sensitivity（CS）,and postoperative haze were assessed.RESULTS：After the surgery,both photopic and mesopic CSs significantly improved（both P〈0.001）. We detected significant induction of OWF coma and trefoil（P〈0.001 for both）HOAs; CWF coma（P=0.002）,spherical（P〈0.001）,and tetrafoil（P=0.003）HOAs in 6 mm analysis diameter; and CWF trefoil（P=0.04）HOA in 4 mm analysis diameter. The range of mean induction observed for various HOAs was0.005-0.11 μm. The 86.7% of eyes reached an uncorrected distance visual acuity of 20/20 or better; 96.7% of eyes were within ±0.5 D of targeted spherical refraction. In vector analysis,mean correction index value was 1.03 and mean index of success was 0.22. By 12mo after the operation,no eye lost any number of corrected distancevisual acuity lines. We detected no corneal haze greater than 1~＋ throughout the follow-up.CONCLUSION：Our findings show promising effects of single-step Trans PRK on quality of vision in high myopic eyes. It also improves refraction and visual acuity.展开更多
AIM: To assess current practice of United Kingdom cardiologists with respect to patients with reported shellfish/iodine allergy, and in particular the use of iodinated contrast for elective coronary angiography.Moreov...AIM: To assess current practice of United Kingdom cardiologists with respect to patients with reported shellfish/iodine allergy, and in particular the use of iodinated contrast for elective coronary angiography.Moreover we have reviewed the current evidence-base and guidelines available in this area.METHODS: A questionnaire survey was send to 500senior United Kingdom cardiologists(almost 50% cardiologists registered with British Cardiovascular Society)using email and first 100 responses used to analyze practise. We involved cardiologists performing coronary angiograms routinely both at secondary and tertiary centres. Three specific questions relating to allergy were asked:(1) History of shellfish/iodine allergy in pre-angiography assessment;(2) Treatments offeredfor shellfish/iodine allergy individuals; and(3) Any specific treatment protocol for shellfish/iodine allergy cases. We aimed to establish routine practice in United Kingdom for patients undergoing elective coronary angiography. We also performed comprehensive PubMed search for the available evidence of relationship between shellfish/iodine allergy and contrast media.RESULTS: A total of 100 responses were received, representing 20% of all United Kingdom cardiologists. Ninety-three replies were received from consultant cardiologists, 4 from non-consultant grades and 3 from cardiology specialist nurses. Amongst the respondents, 66% routinely asked about a previous history of shellfish/iodine allergy. Fifty-six percent would pre-treat these patients with steroids and anti-histamines. The other 44% do nothing, or do nonspecific testing based on their personal experience as following:(1) Skin test with 1 mL of subcutaneous contrast before intravenous contrast;(2) Test dose 2 mL contrast before coronary injection;(3) Close observation for shellfish allergy patients; and(4) Minimal evidence that the steroid and anti-histamine regime is effective but it makes us feel better.CONCLUSION: There is no evidence that allergy to shellfish alters the risk of reaction to 展开更多
基金the sponsorship of the National 973 Program of China (2013CB228604)the National Grand Project for Science and Technology (2011ZX05030-004-002, 2011ZX05019-003 and 2011ZX05006-002) for funding this research+2 种基金the support of the Australian and Western Australian Governments and the North West Shelf Joint Venture Partnersthe Western Australian Energy Research Alliance (WA:ERA)Foundation from Geophysical Key Lab of SINOPEC (WTYJYWX2013-04-01)
文摘Linearized approximations of reflection and transmission coefficients set a foundation for amplitude versus offset（AVO） analysis and inversion in exploration geophysics.However,the weak properties contrast hypothesis of those linearized approximate equations leads to big errors when the two media across the interface vary dramatically.To extend the application of AVO analysis and inversion to high contrast between the properties of the two layers,we derive a novel nonlinearized high-contrast approximation of the PP-wave reflection coefficient,which establishes the direct relationship between PPwave reflection coefficient and P-wave velocities,S-wave velocities and densities across the interface.（A PP wave is a reflected compressional wave from an incident compressional wave（P-wave）.） This novel approximation is derived from the exact reflection coefficient equation with Taylor expansion for the incident angle.Model tests demonstrate that,compared with the reflection coefficients of the linearized approximations,the reflection coefficients of the novel nonlinearized approximate equation agree with those of the exact PP equation better for a high contrast interface with a moderate incident angle.Furthermore,we introduce a nonlinear direct inversion method utilizing the novel reflection coefficient equation as forward solver,to implement the direct inversion for the six parameters including P-wave velocities,S-wave velocities,and densities in the upper and lower layers across the interface.This nonlinear inversion algorithm is able to estimate the inverse of the nonlinear function in terms of model parameters directly rather than in a conventional optimization way.Three examples verified the feasibility and suitability of this novel approximation for a high contrast interface,and we still could estimate the six parameters across the interface reasonably when the parameters in both media across the interface vary about 50%.
基金supported by the National Natural Science Foundation of China(No.12075306)the Natural Science Foundation of Shanghai(No.22ZR1470900)+1 种基金the Key Research Programs in Frontier Science(No.ZDBSLY-SLH006)the China Postdoctoral Science Foundation(No.2021M703328)。
文摘The plasma mirror system was installed on the 1 PW laser beamline of Shanghai Superintense Ultrafast Laser Facility[SULF]for enhancing the temporal contrast of the laser pulse.About 2 orders of magnitude improvement on pulse contrast was measured on picosecond and nanosecond time scales.The experiments show that high-contrast laser pulses can significantly improve the cutoff energy and quantity of proton beams.Then different target distributions are assumed in particles in cell simulations,which can qualitatively assume the expansion of nanometer-scale foil.The high-contrast laser enables the SULF-1PW beamline to generally be of benefit for many potential applications.
基金the generous financial support of the National Key R&D Program of China(grant no.2019YFA0210100)the National Natural Science Foundation of China(grant nos.21890744 and 21877029)+1 种基金the Hunan Postgraduate Research and Innovation Project(grant no.CX2018B187)the China Postdoctoral Science Foundation(grant nos.2019TQ0085 and 2020M682538).
文摘Developing dual-state luminophores(DSLs)with strong fluorescence in both the monomer and aggregate states is urgently needed but remains a huge challenge because most current luminophores are either aggregation-induced emission or aggregation-caused quenching molecules.Moreover,limited by the structural conservation of the few existing DSLs,there are not enough response sites that can be used to customize various activatable fluorescent probes for specific molecular imaging.Herein,we engineered a general integration strategy for the fabrication of such DSLs with excellent photophysical properties.The DSLs,with their tunable spectra,a large Stokes shift(>170 nm),and achievable near-infrared(NIR)emission,show great potential for high-contrast imaging.Importantly,DSLs can be used as a universal platform for probe customization due to their activatable fluorescence through protection-deprotection of the phenolic hydroxyl group.Based on this,an NIR fluorescent probe DSL-Gal was developed for sensing of β-galactosidase in solutions,senescent cells,and liver metastases with high contrast,further confirming the superiority and universal feasibility of DSLs in probe design.The integration strategy may provide a novel approach for the generation of other DSLs and have great potential applications in bioimaging.
基金supported by the "Strategic Priority Research Program" of the Chinese Academy of Sciences(Grant No.XDA04070600)the National Natural Science Foundation of China(Grant Nos.11003031 and 10873024)+1 种基金as well as the National Astronomical Observatories' Special Fund for Astronomy-2009Part of the work described in this paper was carried out at California State University Northridge,with support from the National Science Foundation under Grant ATM-0841440
文摘High-contrast imaging coronagraphs, used for the detection of exoplanets, have always adopted passive coronagraph optical components. It is therefore impossible to actively optimize the coronagraphs to achieve their best performance. To solve this problem, we propose a novel high-contrast imaging coronagraph which combines a liquid crystal array （LCA） for active pupil apodization and a deformable mirror （DM） for phase correction. The LCA we use is an amplitude-only spatial light mod- ulator. The LCA is well calibrated and compensates for its amplitude non-uniformity and nonlinear intensity responsivity. We measured the imaging contrasts of the coron- agraph system with the LCA only and without the DM deployed. Imaging contrasts of 10-4 and 10-5 can be reached at an inner working angular distance of 2.5 and 5A/D, respectively. A simulation shows that the phase errors on the coronagraph pupil limit the contrast performance. The contrast could be further improved if a DM is deployed to correct the phase errors induced by the LCA and coronagraph optics.
基金supported by the National Natural Science Foundation of China(Grant Nos.11374100,91536218,and 11274114)the Natural Science Foundation of Shanghai Municipality,China(Grant No.13ZR1412800)
文摘We propose a novel scheme of optical confinement for atoms by using a concave grating reflector.The two-dimension grating structure with a concave surface shape exhibits strong focusing ability under radially polarized illumination.Especially,the light intensity at the focal point is about 100 times higher than that of the incident light.Such a focusing optical field reflected from the curved grating structure can provide a deep potential to trap cold atoms.We discuss the feasibility of the structure serving as an optical dipole trap.Our results are as follows.（i） Van der Waals attraction potential to the surface of the structure has a low effect on trapped atoms,（ⅱ） The maximum trapping potential is ~1.14 mK in the optical trap,which is high enough to trap cold ^87Rb atoms from a standard magneto-optical trap with a temperature of 120 μK,and the maximum photon scattering rate is lower than 1/s.（ⅲ） Such a microtrap array can also manipulate and control cold molecules,or microscopic particles.
基金Supported by the National Natural Science Foundation of China (Grant No. 10873024)
文摘High-contrast imaging provided by a coronagraph is critical for the direction imaging of the Earth-like planet orbiting its bright parent star.A major limitation for such direct imaging is the speckle noise that is induced from the wave-front error of an optical system.We derive an algorithm for the wave-front measurement directly from 3 focal plane images.The 3 images are achieved through a deformable mirror to provide specific phases for the optics system.We introduce an extra amplitude modulation on one deformable mirror configuration to create an uncorrelated wave-front,which is a critical procedure for wave-front sensing.The simulation shows that the reconstructed wave-front is consistent with the original wave-front theoretically,which indicates that such an algorithm is a promising technique for the wave-front measurement for the high-contrast imaging.
文摘In this paper is considered the reproduction process of high-contrast objects in systems with limited dynamic range.There was proposed an algorithm of forming of high-contrast digital original,
文摘This paper proposed a novel broadband filter using multi-layer sub-wavelength high-contrast grating （HCG） structure. This filter has wide bandwidth and good sideband suppression. We simulated and analyzed the effects of different numbers of layers and different grating indexes on filtering performance of the broadband filter. According to the simulated results, we designed a multi- layer HCG broadband filter, which has bandwidth of 843 nm and center wavelength of 1550 nm.
基金supported by the DOE and NSF(DMS 0934837 and DMS 0811180)supported by Award No.KUS-C1-016-04made by King Abdullah University of Science and Technology(KAUST).
文摘In this paper we use the Generalized Multiscale Finite Element Method(GMsFEM)framework,introduced in[26],in order to solve nonlinear elliptic equations with high-contrast coefficients.The proposed solution method involves linearizing the equation so that coarse-grid quantities of previous solution iterates can be regarded as auxiliary parameters within the problem formulation.With this convention,we systematically construct respective coarse solution spaces that lend themselves to either continuous Galerkin(CG)or discontinuous Galerkin(DG)global formulations.Here,we use Symmetric Interior Penalty Discontinuous Galerkin approach.Both methods yield a predictable error decline that depends on the respective coarse space dimension,and we illustrate the effectiveness of the CG and DG formulations by offering a variety of numerical examples.
基金supported by the National Natural Science Foundation of China(Nos.61674018,61574019 and 61674020)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20130005130001)the Beijing Municipality Natural Science Foundation(No.4132069)
文摘Novel construction of a resonant-cavity-enhanced photodetector(RCE-PD) with monolithic high-contrast grating(HCG)is proposed to overcome the difficulty of fabricating a high reflective mirror of RCE-PD at 1 550 nm. In this structure,HCG serves as the top mirror of the RCE-PD, whereas InGaAs serves as a sacrificial layer to achieve monolithic integration.During the bandwidth optimization, the ratio of the thickness of the total intrinsic region and the absorption layer is introduced to realize the simultaneous optimization of the thickness of spacing layers and absorption layer. After structural optimization, the quantum efficiency of the device with diameter of 20 μm is 82% at 1 550 nm, and the 3-dB bandwidth is 34 GHz at a bias of 3 V.
基金This research was made possible as a result of a generous grant from National Natural Science Foundation of China(nos.21472111 and 21877013)the 111 Project(no.D20015).
文摘High-contrast mechanochromic(MC)materials are prominent candidates for sensor,security,and memory applications;however,the development of materials with a large luminescence change(Δλem>100 nm)under external stimuli is challenging.Considering that polymorphic molecules usually exhibit reversible mechanochromism,polymorph prediction is adopted for thefirst time to guide the design of high-contrastMC materials in this study.We designed and synthesized a series of donor–π–acceptor pyran derivatives bearing different electron donors and acceptors as model systems.The polymorph prediction indicated that 4-dicyanomethylene-2,6-distyryl-4H-pyran and 4H-pyran-4-one derivatives had the potential to crystallize in both monomer andπ-dimer aggregates,while barbituric acid-based compound tended to pack tightly in all aggregated states.The experimental results agreed well with the prediction that the derivatives potentially possessing both monomer andπ-dimer aggregate structures exhibit excellent MC behavior,whereas the fluorescence difference for the barbituric acid-based compounds is minimal.Moreover,a compound with an excellent fluorescence difference of three colors during reversible mechanochromism was chosen as the candidate for an optical recording material and security ink.This work proposes an effective method to guide the design of stimuli-responsive materials,which may open promising avenues for the development of high-contrast MC molecules.
基金Supported by the National Natural Science Foundation of China under Grant No 41675154the Six Major Talent Peak Expert of Jiangsu Province under Grant No 2015-XXRJ-014the Jiangsu 333 High-Level Talent Cultivation Program under Grant No BRA2016425
文摘To achieve the enhancement and manipulation of light absorption in graphene within the visible and near infrared regions, a design consists of high-contrast gratings and two evanescently coupled slabs with graphene monolayer is demonstrated. The operation principle and design process of the proposed structure are analyzed using the coupled mode theory, which is confirmed by the rigorous coupled wave analysis. It is proved that the absorptance of graphene monolayer can be greatly enhanced to unity. The thickness of grating and slab layers can significantly change the line width and resonant mode position in the absorption spectra. Furthermore, high tunability in amplitude and bandwidth of the absorption spectra can be achieved by controlling the structural parameters of the hybrid structure. The proposed devices could be efficiently exploited as tunable and selective absorbers, and could be allowed to realize other two-dimensional materials-based selective photo-detectors.
文摘AIM：To investigate quantitative and qualitative optical outcomes of single-step transepithelial photorefractive keratectomy（Trans PRK）in high myopia.METHODS：In a prospective interventional case-series,30 eyes with high myopia（-6.00 to-8.75 D）with（up to-3.00 D）or without astigmatism were enrolled from Bina Eye Hospital,Tehran,Iran. One-step Trans PRK was performed with aberration-free aspherical optimized profile and SCHWIND AMARIS 500 laser. One-year follow-up results for refraction,visual acuities,vector analysis,ocular wavefront（OWF）and corneal wave-front（CWF）higher order aberrations（HOA）,contrast sensitivity（CS）,and postoperative haze were assessed.RESULTS：After the surgery,both photopic and mesopic CSs significantly improved（both P〈0.001）. We detected significant induction of OWF coma and trefoil（P〈0.001 for both）HOAs; CWF coma（P=0.002）,spherical（P〈0.001）,and tetrafoil（P=0.003）HOAs in 6 mm analysis diameter; and CWF trefoil（P=0.04）HOA in 4 mm analysis diameter. The range of mean induction observed for various HOAs was0.005-0.11 μm. The 86.7% of eyes reached an uncorrected distance visual acuity of 20/20 or better; 96.7% of eyes were within ±0.5 D of targeted spherical refraction. In vector analysis,mean correction index value was 1.03 and mean index of success was 0.22. By 12mo after the operation,no eye lost any number of corrected distancevisual acuity lines. We detected no corneal haze greater than 1~＋ throughout the follow-up.CONCLUSION：Our findings show promising effects of single-step Trans PRK on quality of vision in high myopic eyes. It also improves refraction and visual acuity.
文摘AIM: To assess current practice of United Kingdom cardiologists with respect to patients with reported shellfish/iodine allergy, and in particular the use of iodinated contrast for elective coronary angiography.Moreover we have reviewed the current evidence-base and guidelines available in this area.METHODS: A questionnaire survey was send to 500senior United Kingdom cardiologists(almost 50% cardiologists registered with British Cardiovascular Society)using email and first 100 responses used to analyze practise. We involved cardiologists performing coronary angiograms routinely both at secondary and tertiary centres. Three specific questions relating to allergy were asked:(1) History of shellfish/iodine allergy in pre-angiography assessment;(2) Treatments offeredfor shellfish/iodine allergy individuals; and(3) Any specific treatment protocol for shellfish/iodine allergy cases. We aimed to establish routine practice in United Kingdom for patients undergoing elective coronary angiography. We also performed comprehensive PubMed search for the available evidence of relationship between shellfish/iodine allergy and contrast media.RESULTS: A total of 100 responses were received, representing 20% of all United Kingdom cardiologists. Ninety-three replies were received from consultant cardiologists, 4 from non-consultant grades and 3 from cardiology specialist nurses. Amongst the respondents, 66% routinely asked about a previous history of shellfish/iodine allergy. Fifty-six percent would pre-treat these patients with steroids and anti-histamines. The other 44% do nothing, or do nonspecific testing based on their personal experience as following:(1) Skin test with 1 mL of subcutaneous contrast before intravenous contrast;(2) Test dose 2 mL contrast before coronary injection;(3) Close observation for shellfish allergy patients; and(4) Minimal evidence that the steroid and anti-histamine regime is effective but it makes us feel better.CONCLUSION: There is no evidence that allergy to shellfish alters the risk of reaction to
