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Rapid interrogation of special nuclear materials by combining scattering and transmission nuclear resonance fluorescence spectroscopy 被引量:4
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作者 Hao-Yang Lan Tan Song +2 位作者 Jia-Lin Zhang Jian-Liang Zhou Wen Luo 《Nuclear Science and Techniques》 SCIE EI CAS CSCD 2021年第8期67-77,共11页
The smuggling of special nuclear materials(SNMs)across national borders is becoming a serious threat to nuclear nonproliferation.This paper presents a feasibility study on the rapid interrogation of concealed SNMs by ... The smuggling of special nuclear materials(SNMs)across national borders is becoming a serious threat to nuclear nonproliferation.This paper presents a feasibility study on the rapid interrogation of concealed SNMs by combining scattering and transmission nuclear resonance fluorescence(s NRF and t NRF)spectroscopy.In s NRF spectroscopy,SNMs such as^(235,238)U are excited by a wide-band photon beam of appropriate energy and exhibit unique NRF signatures.Monte Carlo simulations show that one-dimensional scans can realize isotopic identification of concealed^(235,238)U when the detector array used for interrogation has sufficiently high energy resolution.The simulated isotopic ratio^(235U/238)U is in good agreement with the theoretical value when the SNMs are enclosed in relatively thin iron.This interrogation is followed by t NRF spectroscopy using a narrow-band photon beam with the goal of obtaining tomographic images of the concealed SNMs.The reconstructed image clearly reveals the position of the isotope^(235)U inside an iron rod.It is shown that the interrogation time of s NRF and t NRF spectroscopy is one order of magnitude lower than that when only t NRF spectroscopy is used and results in a missed-detection rate of 10^(-3).The proposed method can also be applied for isotopic imaging of other SNMs such as^(239,240)Pu and^(237)Np. 展开更多
关键词 Special nuclear material Nondestructive interrogation Nuclear resonance fluorescence
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Sideband entanglement in collective resonance fluorescence
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作者 张雪华 胡响明 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第11期261-266,共6页
We examine the quantum correlation between the Mollow sidebands in the collective resonance fluorescence from a strongly driven ensemble of two-level atoms. By using the criterion proposed by Shchukin and Vogel, we sh... We examine the quantum correlation between the Mollow sidebands in the collective resonance fluorescence from a strongly driven ensemble of two-level atoms. By using the criterion proposed by Shchukin and Vogel, we show that non-Gaussian entanglement exists between the two separated sidebands. The responsible mechanism is traced to the spontaneous parametric process, in which the nonclassical correlation is established. This suggests that the collective resonance fluorescence provides a continuous source for the non-Gaussian entangled light and thus has great potentials for various applications in quantum information and quantum computation. 展开更多
关键词 collective resonance fluorescence non-Gaussian entanglement spontaneous parametricinteraction
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Monitoring the in vivo siRNA release from lipid nanoparticles based on the fluorescence resonance energy transfer principle 被引量:1
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作者 Lei Sun Jinfang Zhang +11 位作者 Jing-e Zhou JingWang Zhehao Wang Shenggen Luo Yeying Wang Shulei Zhu Fan Yang Jie Tang Wei Lu Yiting Wang Lei Yu Zhiqiang Yan 《Asian Journal of Pharmaceutical Sciences》 SCIE CAS 2023年第1期72-85,共14页
The siRNA-loaded lipid nanoparticles have attracted much attention due to its significant gene silencing effect and successful marketization.However,the in vivo distribution and release of siRNA still cannot be effect... The siRNA-loaded lipid nanoparticles have attracted much attention due to its significant gene silencing effect and successful marketization.However,the in vivo distribution and release of siRNA still cannot be effectively monitored.In this study,based on the fluorescence resonance energy transfer(FRET)principle,a fluorescence dye Cy5-modified survivin siRNA was conjugated to nanogolds(Au-DR-siRNA),which were then wrapped with lipid nanoparticles(LNPs)for monitoring the release behaviour of siRNA in vivo.The results showed that once Au-DR-siRNA was released from the LNPs and cleaved by the Dicer enzyme to produce free siRNA in cells,the fluorescence of Cy5 would change from quenched state to activated state,showing the location and time of siRNA release.Besides,the LNPs showed a significant antitumor effect by silencing the survivin gene and a CT imaging function superior to iohexol by nanogolds.Therefore,this work provided not only an effective method for monitoring the pharmacokinetic behaviour of LNP-based siRNA,but also a siRNA delivery system for treating and diagnosing tumors. 展开更多
关键词 Survivin siRNA Lipid nanoparticles In vivo release Nanogolds fluorescence resonance energy transfer
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A novel fluorescence sensor for milk clotting enzyme chymosin using peptide as substrate and covalent organic framework nanosheet as fluorescence quencher
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作者 Xiaokang Lu Tianle Qi +5 位作者 Linjiang Guo Lin Xiao Hanbin Xu Guobao Ning Hui Zhao Canpeng Li 《Food Science and Human Wellness》 SCIE CAS CSCD 2024年第6期3606-3613,共8页
Chymosin is one of the critical enzymes in cheese making.Herein,we proposed a novel fluorometric assay for chymosin determination.Firstly,covalent organic frameworks(COF)were synthesized and exfoliated to 2-dimensiona... Chymosin is one of the critical enzymes in cheese making.Herein,we proposed a novel fluorometric assay for chymosin determination.Firstly,covalent organic frameworks(COF)were synthesized and exfoliated to 2-dimensional COF nanosheets(COF NS)by ultrasound treatment.Gold nanoparticles(Au NPs)were loaded with COF NS to prepare AuNPs/COF NS(Au@COF NS).Secondly,rhodamine B(RhB)modified substrate peptide(Pep)for chymosin was linked with Au@COF NS to construct a Pep-Au@COF NS nanocomposite.For the sensing principle,fluorescence of RhB was quenched by Au@COF NS and the fluorescence intensity was weak due to the fluorescence resonance energy transfer between COF NS and RhB of Pep.However,in the presence of chymosin,the RhB was released by specific cleavage of the substrate peptide by chymosin and resulted in the recovery of fluorescence.The increased fluorescence intensity was proportional to the increase of chymosin concentration and thus a“turn on”fluorescent sensor for chymosin was constructed.The sensor showed a linear range in the concentration of 0.05-60.00μg/mL for the detection of chymosin with a detection limit of 20 ng/mL.The sensor was used to quantify chymosin in rennet product with good selectivity,which has the potential applications in cheese manufacturing. 展开更多
关键词 Covalent organic framework fluorescence sensor CHYMOSIN fluorescence resonance energy transfer
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A mini review and hypothesis for coronavirus detection using photonics: surface enhanced Raman scattering and fluorescence resonance energy transfer
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作者 Akshat Dharmeshkumar Modi Austin Tian Yang Akriti Sharma 《Infectious Diseases Research》 2023年第1期10-13,共4页
COVID-19 has devastated numerous nations around the world and has overburdened numerous healthcare systems,which has also caused the loss of livelihoods due to prolonged shutdowns and further led to a cascading effect... COVID-19 has devastated numerous nations around the world and has overburdened numerous healthcare systems,which has also caused the loss of livelihoods due to prolonged shutdowns and further led to a cascading effect on the global economy.COVID-19 infections have an incubation period of 2–7 days,but 40 to 45%of cases are asymptomatic or show mild to moderate respiratory symptoms after the period due to subclinical lung abnormalities,making it more likely to spread the pandemic disease.To restrict the spread of the virus,on-site diagnosis methods that are quicker,more precise,and easily accessible are required.Rapid Antigen Detection Tests and Polymerase Chain Reaction tests are currently the primary methods used to determine the presence of COVID-19 viruses.These tests are typically time-consuming,not accurate,and,more importantly,not available to everyone.Hence,in this review and hypothesis,we proposed equipment that employs the properties of photonics to improve the detection of COVID-19 viruses by taking the advantage of typical binding of coronavirus with angiotensin-converting enzyme 2(ACE2)receptors.This hypothetical model would combine Surface-Enhanced Raman Scattering(SERS)and Fluorescence Resonance Energy Transfer(FRET)to provide great flexibility,high sensitivities,and enhanced accessibility. 展开更多
关键词 COVID-19 CORONAVIRUS ACE2 virus detection PHOTONICS surface-enhanced Raman scattering fluorescence resonance energy transfer
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Screening and identification of bioactive compounds from citrus against non-structural protein 3 protease of hepatitis C virus genotype 3a by fluorescence resonance energy transfer assay and mass spectrometry 被引量:1
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作者 Mahim Khan Waqar Rauf +2 位作者 Fazal-e-Habib Moazur Rahman Mazhar Iqbal 《World Journal of Hepatology》 2020年第11期976-992,共17页
BACKGROUND Hepatitis C virus genotype 3a(HCV G3a)is highly prevalent in Pakistan.Due to the elevated cost of available Food and Drug Administration-approved drugs against HCV,medicinal natural products of potent antiv... BACKGROUND Hepatitis C virus genotype 3a(HCV G3a)is highly prevalent in Pakistan.Due to the elevated cost of available Food and Drug Administration-approved drugs against HCV,medicinal natural products of potent antiviral activity should be screened for the cost-effective treatment of the disease.Furthermore,from natural products,active compounds against vital HCV proteins like non-structural protein 3(NS3)protease could be identified to prevent viral proliferation in the host.AIM To develop cost-effective HCV genotype 3a NS3 protease inhibitors from citrus fruit extracts.METHODS Full-length NS3 without co-factor non-structural protein 4A(NS4A)and codon optimized NS3 protease in fusion with NS4A were expressed in Escherichia coli.The expressed protein was purified by metal ion affinity chromatography and gel filtration.Citrus fruit extracts were screened using fluorescence resonance energy transfer(FRET)assay against the protease and polyphenols were identified as potential inhibitors using electrospray ionization-mass spectrometry(MS)/MS technique.Among different polyphenols,highly potent compounds were screened using molecular modeling approaches and consequently the most active compound was further evaluated against HCV NS4A-NS3 protease domain using FRET assay.RESULTS NS4A fused with NS3 protease domain gene was overexpressed and the purified protein yield was high in comparison to the lower yield of the full-length NS3 protein.Furthermore,in enzyme kinetic studies,NS4A fused with NS3 protease proved to be functionally active compared to full-length NS3.So it was concluded that co-factor NS4A fusion is essential for the purification of functionally active protease.FRET assay was developed and validated by the half maximal inhibitory concentration(IC50)values of commercially available inhibitors.Screening of citrus fruit extracts against the native purified fused NS4A-NS3 protease domain showed that the grapefruit mesocarp extract exhibits the highest percentage inhibition 91%of protease activity.Among the compounds identified by LCMS analysis,hesperidin showed strong binding affinity with the protease catalytic triad having S-score value of-10.98.CONCLUSION Fused NS4A-NS3 protease is functionally more active,which is effectively inhibited by hesperidin from the grapefruit mesocarp extract with an IC50 value of 23.32μmol/L. 展开更多
关键词 Hepatitis C virus genotype 3a Non-structural protein 3 protease fluorescence resonance energy transfer assay Citrus extract Mass spectrometry HESPERIDIN
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Investigation of fluorescence resonance energy transfer ultrafast dynamics in electrostatically repulsed and attracted exciton-plasmon systems
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作者 Hong-Yu Tu Ji-Chao Cheng +7 位作者 Gen-Cai Pan Lu Han Bin Duan Hai-Yu Wang Qi-Dai Chen Shu-Ping Xu Zhen-Wen Dai Ling-Yun Pan 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第2期529-534,共6页
Following the gradual maturation of synthetic techniques for nanomaterials,exciton-plasmon composites have become a research hot-spot due to their controllable energy transfer through electromagnetic fields on the nan... Following the gradual maturation of synthetic techniques for nanomaterials,exciton-plasmon composites have become a research hot-spot due to their controllable energy transfer through electromagnetic fields on the nanoscale.However,most reports ignore fluorescence resonance energy transfer(FRET)under electrostatic repulsion conditions.In this study,the FRET process is investigated in both electrostatic attraction and electrostatic repulsion systems.By changing the Au:quantum dot ratio,local-field induced FRET can be observed with a lifetime of ns and a fast component of hundreds of ps.These results indicate that the intrinsic transfer process can only elucidated by considering both steady and transient state information. 展开更多
关键词 fluorescence resonance energy transfer(FRET) quantum dots excitons-plasmon composites
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Retraction Note:Screening and identification of bioactive compounds from citrus against non-structural protein 3 protease of hepatitis C virus genotype 3a by fluorescence resonance energy transfer assay and mass spectrometry
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作者 Mahim Khan Waqar Rauf +2 位作者 Fazal-E-Habib Moazur Rahman Mazhar Iqbal 《World Journal of Hepatology》 2022年第7期1528-1529,共2页
Retraction note:Khan M,Rauf W,Habib F,Rahman M,Iqbal M.Screening and identification of bioactive compounds from citrus against non-structural protein 3 protease of hepatitis C virus genotype 3a by fluorescence resonan... Retraction note:Khan M,Rauf W,Habib F,Rahman M,Iqbal M.Screening and identification of bioactive compounds from citrus against non-structural protein 3 protease of hepatitis C virus genotype 3a by fluorescence resonance energy transfer assay and mass spectrometry.World J Hepatol 2020;12(11):976-992 PMID:33312423 DOI:10.4254/wjh.v12.i11.976.The online version of the original article can be found at https://www.wjgnet.com/1948-5182/full/v12/i11/976.htm. 展开更多
关键词 Non-structural protein 3 Hepatitis C virus Genotype 3a fluorescence resonance energy transfer
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Enhancing the Photosensitivity of Hypocrellin A by Perylene Diimide Metallacage‑Based Host–Guest Complexation for Photodynamic Therapy
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作者 Rongrong Li Tianfeng Yang +7 位作者 Xiuhong Peng Qian Feng Yali Hou Jiao Zhu Dake Chu Xianglong Duan Yanming Zhang Mingming Zhang 《Nano-Micro Letters》 SCIE EI CAS CSCD 2024年第11期71-87,共17页
The development of supramolecular hosts which can efficiently encapsulate photosensitizers to improve the photodynamic efficacy holds great promise for cancer therapy.Here,we report two perylene diimide-based metallac... The development of supramolecular hosts which can efficiently encapsulate photosensitizers to improve the photodynamic efficacy holds great promise for cancer therapy.Here,we report two perylene diimide-based metallacages that can form stable host–guest complexes with planar conjugated molecules including polycyclic aromatic hydrocarbons and photosensitizers(hypocrellin A).Such host–guest complexation not only prevents the aggregation of photosensitizers in aqueous environments,but also offers fluorescence resonance energy transfer(FRET)from the metallacage to the photosensitizers to further improve the singlet oxygen generation(Φ_(Δ)=0.66).The complexes are further assembled with amphiphilic polymers,forming nanoparticles with improved stability for anticancer study.Both in vitro and in vivo studies indicate that the nanoparticles display excellent anticancer activities upon light irradiation,showing great potential for cancer photodynamic therapy.This study provides a straightforward and effective approach for enhancing the photosensitivity of conventional photosensitizers via host–guest complexation-based FRET,which will open a new avenue for host–guest chemistry-based supramolecular theranostics. 展开更多
关键词 Metallacages Host-guest interactions fluorescence resonance energy transfer Singlet oxygen Photodynamic therapy
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Chiral multiple-resonance thermally activated delayed fluorescence materials based on chiral spiro-axis skeleton for efficient circularly polarized electroluminescence
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作者 Shi-Quan Song Xiao Han +4 位作者 Zhong-Zhong Huo Ching-Fai Yip Xian-Fang Hong Meng-Ning Ding You-Xuan Zheng 《Science China Chemistry》 SCIE EI CAS CSCD 2024年第7期2257-2264,共8页
Chiral luminescence materials have potential applications in the field of three-dimensional displays due to their circularly polarized luminescence(CPL)characteristics.However,the further development of circularly pol... Chiral luminescence materials have potential applications in the field of three-dimensional displays due to their circularly polarized luminescence(CPL)characteristics.However,the further development of circularly polarized organic light-emitting diodes(CP-OLEDs)needs to meet the requirements of high efficiency,high color purity,low cost,and high dissymmetry factor(gPLor gEL),chiral multiple resonance thermally activated delayed fluorescence(MR-TADF)materials are considered as candidates in these aspects.Herein,based on a pair of chiral spirofluorene precursors,two pairs of high-performance chiral MR-TADF emitters((R/S)-p-Spiro-DtBuCzB and(R/S)-m-Spiro-DtBuCzB)are developed,which exhibit strong emissions peaking at 491 and 502 nm in toluene with full-width at half-maximum values of 25 and 33 nm,respectively.In addition,small singlet–triplet energy gaps of 0.15 and 0.10 eV with high absolute photoluminescence efficiencies of 95.0%and 96.7%are observed for p-Spiro-DtBuCzB and m-Spiro-DtBuCzB molecules,respectively.OLEDs based on p-Spiro-DtBuCzB and m-Spiro-DtBuCzB display high maximum external quantum efficiencies of 29.6%and 33.8%,respectively.Most importantly,CP-OLEDs present symmetric circularly polarized electroluminescence spectra with|gEL|factors of 3.36×10^(-4)and 7.66×10^(-4)for devices based on(R/S)-p-Spiro-DtBuCzB and(R/S)-m-Spiro-DtBuCzB enantiomers,respectively. 展开更多
关键词 chiral spiro-axis skeleton-based material multiple resonance thermally activated delayed fluorescence circularly polarized electroluminescence dissymmetry factor external quantum efficiency
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Degenerate cascade fluorescence: Optical spectral-line narrowing via a single microwave cavity
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作者 Liang Hu Xiang-Ming Hu Qing-Ping Hu 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第6期346-358,共13页
For a three-level atom, two nondegenerate(even microwave and optical) electric dipole transitions are usually allowed;for either of these, the fluorescence spectra are well-described in terms of spontaneous transition... For a three-level atom, two nondegenerate(even microwave and optical) electric dipole transitions are usually allowed;for either of these, the fluorescence spectra are well-described in terms of spontaneous transitions from a triplet of dressed sublevels to an adjacent lower-lying triplet. When the three dressed sublevels are equally spaced from each other, a remarkable feature known as degenerate cascade fluorescence takes place, which displays a five-peaked structure. We show that a single cavity can make all the spectral lines extremely narrow, whether they arise from cavity-coupled or cavity-free transitions. This effect is based on intrinsic cascade lasing feedback and makes it possible to use a single microwave cavity(even a bad cavity) to narrow the spectral lines in the optical frequency regime. 展开更多
关键词 resonance fluorescence narrow spectral lines microwave cavity
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Interaction of Surface-active Fluorescence Probes with Bovine Serum Albumin
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作者 TongKuanXU XingHalSHEN +1 位作者 NaLI HongChengGAO 《Chinese Chemical Letters》 SCIE CAS CSCD 2005年第7期943-946,共4页
The binding between three surface-active substituted 3H-indole fluorescence probes and bovine serum albumin (BSA) in aqueous solution was studied using fluorescence quenching. The binding constants of 3H-indole molecu... The binding between three surface-active substituted 3H-indole fluorescence probes and bovine serum albumin (BSA) in aqueous solution was studied using fluorescence quenching. The binding constants of 3H-indole molecules with BSA were obtained. According to the F?rster resonance energy transfer theory, the distances between 3H-indole molecules and tryptophan of BSA were calculated. The results show that the oligoethyloxyethylene chain of 3H-indole molecules is longer, the binding between them is stronger, the energy transfer efficiency is higher, and the distance between tryptophan and 3H-indole is nearer. 展开更多
关键词 Substituted 3H-indole quaternary ammonium molecule bovine serum albumin fluorescence resonance energy transfer.
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Polymeric dual-modal imaging nanoprobe with two-photon aggregation-induced emission for fluorescence imaging and gadolinium-chelation for magnetic resonance imaging
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作者 Xueyang Xiao Hao Cai +9 位作者 Qiaorong Huang Bing Wang Xiaoming Wang Qiang Luo Yinggang Li Hu Zhang Qiyong Gong Xuelei Ma Zhongwei Gu Kui Luo 《Bioactive Materials》 SCIE CSCD 2023年第1期538-549,共12页
Nanoprobes that offer both fluorescence imaging(FI)and magnetic resonance imaging(MRI)can provide supplementary information and hold synergistic advantages.However,synthesis of such dual-modality imaging probes that s... Nanoprobes that offer both fluorescence imaging(FI)and magnetic resonance imaging(MRI)can provide supplementary information and hold synergistic advantages.However,synthesis of such dual-modality imaging probes that simultaneously exhibit tunability of functional groups,high stability,great biocompatibility and desired dual-modality imaging results remains challenging.In this study,we used an amphiphilic block polymer from(ethylene glycol)methyl ether methacrylate(OEGMA)and N-(2-hydroxypropyl)methacrylamide(HPMA)derivatives as a carrier to conjugate a MR contrast agent,Gd-DOTA,and a two-photon fluorophore with an aggregation-induced emission(AIE)effect,TPBP,to construct a MR/two-photon fluorescence dual-modality contrast agent,Gd-DOTA-TPBP.Incorporation of gadolinium in the hydrophilic chain segment of the OEGMA-based carrier resulted in a high r_(1)value for Gd-DOTA-TPBP,revealing a great MR imaging resolution.The contrast agent specifically accumulated in the tumor region,allowing a long enhancement duration for vascular and tumor contrast-enhanced MR imaging.Meanwhile,coupling TPBP with AIE properties to the hydrophobic chain segment of the carrier not only improved its water solubility and reduced its cytotoxicity,but also significantly enhanced its imaging performance in an aqueous phase.Gd-DOTA-TPBP was also demonstrated to act as an excellent fluorescence probe for two-photon-excited bioimaging with higher resolution and greater sensitivity than MRI.Since high-resolution,complementary MRI/FI dual-modal images were acquired at both cellular and tissue levels in tumor-bearing mice after application of Gd-DOTA-TPBP,it has great potential in the early phase of disease diagnosis. 展开更多
关键词 RAFT polymerization Amphiphilic block polymers Magnetic resonance/fluorescence dual-modal imaging Tumor/vascular imaging Two-photon AIE fluorescent contrast agent
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Resonantly driven exciton Rabi oscillation in single quantum dots emitting at 1300 nm 被引量:3
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作者 薛永洲 陈泽升 +4 位作者 倪海桥 牛智川 江德生 窦秀明 孙宝权 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第8期185-188,共4页
We report on the resonance fluorescence (RF) from single InAs quantum dots (QDs) emitting at the telecom band of 1300 nm. The InAs/GaAs QDs are embedded in a planar optical microcavity and the RF is measured by an... We report on the resonance fluorescence (RF) from single InAs quantum dots (QDs) emitting at the telecom band of 1300 nm. The InAs/GaAs QDs are embedded in a planar optical microcavity and the RF is measured by an orthogonal excitation-detection geometry for deeply suppressing the residual laser scattering. An ultra-weak He-Ne laser is necessary to be used as a gate laser for obtaining RE Rabi oscillation with more than one period is observed through the picosecond (ps) pulsed laser excitation. The resonant control of exciton opens up new possibilities for realizing the on-demand single photon emission and quantum manipulation of solid-state qubits at telecom band. 展开更多
关键词 quantum dots resonance fluorescence single photons Rabi oscillation
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Observation of amyloid precursor protein cleavage and Aβ generation in living cells by using multiphoton laser scanning microscopy
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作者 李晓晴 张苏明 +1 位作者 杨华静 张智红 《Neuroscience Bulletin》 SCIE CAS CSCD 2007年第5期256-262,共7页
Objective To investigate the proteolytic mechanism of amyloid precursor protein (APP) and to explore amyloidbeta (Aβ) generation in living neurons. Methods DNA fragments were amplified by PCR or synthesized. The ... Objective To investigate the proteolytic mechanism of amyloid precursor protein (APP) and to explore amyloidbeta (Aβ) generation in living neurons. Methods DNA fragments were amplified by PCR or synthesized. The four fragments, CFP, 54bp, YFP and C99 were ligated into pcDNA3.0 vector to construct the recombinant plasmids pcDNA3.0-CFP-54bp- YFP and pcDNA3.0-CFP-54bp-YFP-C99. The SH-SY5Y cells were transiently transfected with pcDNA3.0-CFP-54bp-YFP or pcDNA3.0-CFP-54bp-YFP-C99. The expression of fusion gene was examined under a multiphoton laser scanning microscope. Fluorescence resonance energy transfer (FRET) was used to measure the β cleavage and γ cleavage of APE Aβ generation was confirmed by immunocytochemistry and multiphoton laser scanning microscopy. Cell viability was tested by MTT assay at different time points. Results (1) The double restriction endonuclease digestion and sequencing analysis confirmed the authenticity of the recombinant plasmids pcDNA3.0-CFP-54bp-YFP and pcDNA3.0-CFP-54bp- YFP-C99. (2) Blue and yellow fluorescences were detected in the transfected cells. (3) FRET occurred in pcDNA3.0-CFP- 54bp-YFP-transfected cells but not in pcDNA3.0-CFP-54bp-YFP-C99-transfected cells. (4) Aβ was produced in the pcDNA3.0- CFP-54bp-YFP-C99 transfected cells. (5) Aβ-deposition was widespread in the cell. (6) Cell viability decreased along with the intracellular Aβ deposition. Conclusion C99 is important for the APP β cleavage. Aβ may be generated and deposited in cells at the early stage of Alzheimer's disease. Intracellular Aβ accumulation brings deleterious effects on cells. 展开更多
关键词 amyloid precursor protein amyloid beta protein beta-cleavage fluorescence resonance energy transfer
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Anomalous Effects of Driving Field Linewidth on a One-Atom Dressed-State Laser
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作者 杨金金 胡响明 《Chinese Physics Letters》 SCIE CAS CSCD 2007年第5期1256-1259,共4页
We examine the effects of driving field linewidth on a one-atom dressed state laser. Unexpectedly, the linewidth leads to anomalous effects on the cavity field. The mean photon number of the cavity field is raised or ... We examine the effects of driving field linewidth on a one-atom dressed state laser. Unexpectedly, the linewidth leads to anomalous effects on the cavity field. The mean photon number of the cavity field is raised or the normalized variance is reduced to a certain degree as the linewidth increases for an appropriate range of parameters. The responsible mechanism is attributed to the fluctuation-induced modification of the electromagnetic reservoir where the atom stays. 展开更多
关键词 SPONTANEOUS-EMISSION SINGLE-ATOM resonance fluorescence OPTICALBISTABILITY CAVITY SUPPRESSION ABSORPTION INVERSION SPECTRUM
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Two-Time Intensity Correlations and Multiple Interference Mechanisms in a Driven Cascade Atom
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作者 王飞 胡响明 《Chinese Physics Letters》 SCIE CAS CSCD 2007年第2期432-435,共4页
We examine the intensity correlation functions of the two fluorescent fields that are emitted from the top and middle states of a doubly driven three-level atom in the cascade configuration. Novel interference effects... We examine the intensity correlation functions of the two fluorescent fields that are emitted from the top and middle states of a doubly driven three-level atom in the cascade configuration. Novel interference effects are shown. (i) Both of the fluorescent fields have anticorrelations which can exist for long times when the applied fields are on the two-photon resonance and far off one.photon resonances. (ii) Both of the fluorescent fields have strong correlations when the applied fields are far off one- and two-photon resonances. In particular, the extremely strong correlation occurs for the photons emitted from the top state. The above phenomena are traced to the multiple interference mechanisms. 展开更多
关键词 SPONTANEOUS EMISSION CANCELLATION ELECTROMAGNETICALLY INDUCED TRANSPARENCY QUANTUM INTERFERENCE resonance fluorescence PHOTONIC CRYSTAL INVERSION SYSTEMS LASER
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Observation of linewidth narrowing due to a spontaneously generated coherence effect
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作者 田思聪 王春亮 +7 位作者 康智慧 杨秀彬 万仁刚 张晓军 张航 姜云 崔海宁 高锦岳 《Chinese Physics B》 SCIE EI CAS CSCD 2012年第6期216-222,共7页
We investigate the resonance fluorescence spectrum of an atomic three-level ladder system driven by two laser fields. We show that such a system emulates to a large degree a V-type atom with parallel dipole moments-th... We investigate the resonance fluorescence spectrum of an atomic three-level ladder system driven by two laser fields. We show that such a system emulates to a large degree a V-type atom with parallel dipole moments-the latter being a system that exhibits spontaneously generated coherence and can display ultrasharp spectral lines. We find a suitable energy scheme in a SSRb atom and experimentally observe the narrowing of the central peak in a rubidium atomic beam. The corresponding spectrum can convindngiy demonstrate the existence of spontaneously generated coherence. 展开更多
关键词 spontaneously generated coherence resonance fluorescence linewidth narrowing atomicbeam
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Two-dimensional atom localization induced by a squeezed vacuum
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作者 王飞 徐俊 《Chinese Physics B》 SCIE EI CAS CSCD 2016年第10期139-148,共10页
A scheme of two-dimensional(2D) atom localization induced by a squeezed vacuum is proposed, in which the threelevel V-type atoms interact with two classical standing-wave fields. It is found that when the environment ... A scheme of two-dimensional(2D) atom localization induced by a squeezed vacuum is proposed, in which the threelevel V-type atoms interact with two classical standing-wave fields. It is found that when the environment is changed from an ordinary vacuum to a squeezed vacuum, the 2D atom localization is realized by detecting the position-dependent resonance fluorescence spectrum. For comparison, we demonstrate that the atom localization originating from the quantum interference effect is distinct from that induced by a squeezed vacuum. Furthermore, the combined effects of the squeezed vacuum and quantum interference are also discussed under appropriate conditions. The internal physical mechanism is analyzed in terms of dressed-state representation. 展开更多
关键词 atom localization squeezed vacuum resonance fluorescence
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Preassembly and ligand-induced restructuring of the chains of the IFN-γ receptor complex: the roles of Jak kinases, Statl and the receptor chains 被引量:7
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作者 Christopher D Krause Natasha Lavnikova +5 位作者 Junxia Xie Erwen Mei Olga V Mirochnitchenko Yiwei Jia Robin M Hochstrasser Sidney Pestka 《Cell Research》 SCIE CAS CSCD 2006年第1期55-69,共15页
We previously demonstrated using noninvasive technologies that the interferon-gamma (IFN-γ) receptor complex is preassembled [ 1 ]. In this report we determined how the receptor complex is preassembled and how the ... We previously demonstrated using noninvasive technologies that the interferon-gamma (IFN-γ) receptor complex is preassembled [ 1 ]. In this report we determined how the receptor complex is preassembled and how the ligand-mediated conformational changes occur. The interaction of Statl with IFN-γR1 results in a conformational change localized to IFN- γR1. Jakl but not Jak2 is required for the two chains of the IFN-γ receptor complex (IFN-γR1 and IFN-γR2) to interact; however, the presence of both Jakl and Jak2 is required to see any ligand-dependant conformational change. Two IFN- γR2 chains interact through species-specific determinants in their extracellular domains. Finally, these determinants also participate in the interaction of IFN-γR2 with IFN-γR1. These results agree with a detailed model of the IFN-γ receptor that requires the receptor chains to be pre-associated constitutively for the receptor to be active. 展开更多
关键词 INTERFERON-GAMMA RECEPTORS fluorescence resonance energy transfer interactions CYTOKINES species specificity Janus kinase Stat protein MUTAGENESIS
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