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  • Interference of the scattered vector light fields from two optically levitated nanoparticles

    分类: 光学 >> 量子光学 提交时间: 2023-02-19

    摘要: We experimentally study the interference of dipole scattered light from two optically levitated nanoparticles in vacuum, which present an environment free of particle-substrate interactions. We illuminate the two trapped nanoparticles with a linearly polarized probe beam orthogonal to the propagation of the trapping laser beams. The scattered light from the nanoparticles are collected by a high numerical aperture (NA) objective lens and imaged. The interference fringes from the scattered vector light for the different dipole orientations in image and Fourier space are observed. Especially, the interference fringes of two scattered light fields with polarization vortex show the {\pi} shift of the interference fringes between inside and outside the center region of the two nanoparticles in the image space. As far as we know, this is the first experimental observation of the interference of scattered vector light fields from two dipoles in free space. This work also provides a simple and direct method to determine the spatial scales between optically levitated nanoparticles by the interference fringes.

  • Imaging the dipole scattering of an optically levitated dielectric nanoparticle

    分类: 光学 >> 量子光学 提交时间: 2023-02-19

    摘要: We experimentally observe the dipole scattering of a nanoparticle using a high numerical aperture (NA) imaging system. The optically levitated nanoparticle provides an environment free of particle-substrate interaction. We illuminate the silica nanoparticle in vacuum with a 532 nm laser beam orthogonally to the propagation direction of the 1064 nm trapping laser beam strongly focused by the same high NA objective used to collect the scattering, which results in a dark background and high signal-noise ratio. The dipole orientations of the nanoparticle induced by the linear polarization of the incident laser are studied by measuring the scattering light distribution in the image and the Fourier space (k-space) as we rotate the illuminating light polarization. The polarization vortex (vector beam) is observed for the special case, when the dipole orientation of the nanoparticle is aligned along the optical axis of the microscope objective. Our work offers an important platform for studying the scattering anisotropy with Kerker conditions.

  • 6 GHz hyperfast rotation of an optically levitated nanoparticle in vacuum

    分类: 光学 >> 量子光学 提交时间: 2023-02-19

    摘要: We report an experimental observation of a record-breaking ultra-high rotation frequency about 6 GHz in an optically levitated nanoparticle system. We optically trap a nanoparticle in the gravity direction with a high numerical aperture (NA) objective lens, which shows significant advantages in compensating the influences of the scattering force and the photophoretic force on the trap, especially at intermediate pressure (about 100 Pa). This allows us to trap a nanoparticle from atmospheric to low pressure ($10^{-3}$ Pa) without using feedback cooling. We measure a highest rotation frequency about 4.3 GHz of the trapped nanoparticle without feedback cooling and a 6 GHz rotation with feedback cooling, which is the fastest mechanical rotation ever reported to date. Our work provides useful guides for efficiently observing hyperfast rotation in the optical levitation system, and may find various applications such as in ultrasensitive torque detection, probing vacuum friction, and testing unconventional decoherence theories.

  • Summary of evidence for the use of Chinese medicine nursing in symptom management of lung cancer patients

    分类: 护理学 >> 护理学 提交时间: 2024-02-22

    摘要: ObjectivesTo search and summarizethe best evidence of traditional Chinese medicine nursing in symptom management of lung cancer patients, so as to provide reference for medical staff to implement traditional Chinese medicine characteristic symptom management for lung cancer patients.BackgroundPatients with lung cancer often have treatment-related symptoms during treatment, which greatly reduces the quality of life of patients and increases the treatment cost of patients. Traditional Chinese medicine nursing technology plays a role in reducing adverse reactions, improving tumor complications and improving the quality of life.DesignAn integrative review of the study.MethodsAll evidence from guideline collaborative networks, professional association websites, and well-known domestic and international databases in the last 10 years was searched. Literature quality evaluation tools were used to evaluate the quality of the included literature, and evidence was extracted from those that met the quality requirements.The PRISMA checklist was used to evaluate the current study.ResultsA total of 34 best evidences of the use of Chinese medicine nursing in symptom management of lung cancer patients were obtained. They are from three aspects: symptom management, emotions, and diet.ConclusionThe existing evidence shows that traditional Chinese medicine nursing has certain curative effect in the symptom management of lung cancer patients. In order to promote the standardized application of traditional Chinese medicine nursing, more clinical research, systematic evaluation and other evidence are still needed in the future.Relevance to Clinical PracticeThis studysummarizes the evidence for the use of Chinese medicine nursing in symptom management of lung cancer patients and provides clinical decision-making for clinical nursing staff to carry out traditional Chinese medicine nursing in the management of lung cancer symptoms.Patient or Public Contribution/sThere are no patient or public contributions to this study.

  • Radiation induced modifications on structural and luminescence properties of LDPE–Na2SO4:Sm3+ composites by γ-ray

    分类: 物理学 >> 凝聚态:结构、力学和热性能 提交时间: 2017-03-23

    摘要: A comparative study on the morphology, structure and luminescence modifications of LDPE–Na2SO4:Sm3+ composite induced by gamma irradiation was reported for the first time. The composites were irradiated with irradiation doses of 10, 30, and 50 kGy in air at room temperature. Modifications on structural and luminescence properties of LDPE–Na2SO4:Sm3+ composites were investigated by using several analytical methods. The X-ray diffraction (XRD) patterns revealed that the cross-linking improved the crystallinity of the composites. Scanning electron microscope (SEM) images illustrated the surface modifications of composites induced by irradiation. Results of positron annihilation lifetime spectroscopy (PALS) suggested that gamma irradiation affected the free volumes concentrations in the samples. The photoluminescence (PL) spectra of non-irradiated and irradiated composites consisted of four main peaks at 563, 598, 644 and 706 nm which could be assigned to the 4G5/2 6HJ (J =5/2, 7/2, 9/2 and 11/2, respectively) transitions within the electronic configuration of Sm3+. Meanwhile, we observed an additional peak at about 686 nm in the irradiated composites, owing to the conversion of Sm3+ Sm2+. Concentrations of the Sm2+ centers linearly increased with gamma irradiation doses, which partly accounted for the degradation of PL intensity of Sm3+ peaks.

  • Synthesis and luminescence properties of Sm-doped LDPE-Na2SO4 composite material

    分类: 物理学 >> 凝聚态:结构、力学和热性能 提交时间: 2017-03-26

    摘要: A series of Sm-doped LDPE-Na2SO4 composites were successfully achieved by melt mixing and hot pressing methods. Their morphology, structure and luminescent properties were characterized by scanning electron microscope (SEM), Energy Dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and photoexcitation (PE), photoluminescence (PL) spectra, respectively. The sizes and concentrations of free volume cavities in composites were studied by positron annihilation lifetime spectroscopy (PALS). SEM micrographs showed that Na2SO4:Sm3+ particles were well-distributed in the polymer matrix. XRD analyses revealed that the addition of Na2SO4:Sm3+ had no effect on the original crystal structure of LDPE. The dominant photoexcitation peak was observed at about 402 nm. The photoluminescence spectra consisted of four main peaks at 563, 598, 644 and 706 nm which could be associated to the transitions 4G5/2→6HJ (J=5/2, 7/2, 9/2 and 11/2, respectively) within the 4f5 electronic configuration of Sm3+. The effect of different doping concentration of Na2SO4:Sm3+ on the luminescent properties of the composites was investigated. The luminescent intensity of the composites increased with phosphor concentration.

  • Milestone progress of the HEPS booster commissioning

    分类: 物理学 >> 核物理学 提交时间: 2023-12-28

    摘要: The High Energy Photon Source (HEPS) is the first fourth-generation synchrotron light source building in China. Its injector consists of a Linac and a full energy booster. The booster captures the electron beam from the Linac and further increases its energy to the same as that required by the storage ring. The full-energy beam could be injected to the storage ring directly or after high-energy accumulation. On November 17, 2023, it was demonstrated that key parameters of the booster successfully reached corresponding target values. These milestone results were accomplished based on many contributions, including nearly a decade of physics design, years of development and installation of equipment, as well as months of beam commissioning. As measured at the extraction energy of 6 GeV, the averaged beam current and emittance reached 8.57 mA with 5 bunches and 30.37 nm.rad with a single-bunch charge of 5.58 nC, compared with the corresponding target values of 6.6 mA and 35 nm.rad, respectively. This paper presents the physics design, equipment development and installation, and commissioning process of the HEPS booster.

  • Surveillance of SARS-CoV-2 at the Huanan Seafood Market

    分类: 医学、药学 >> 预防医学与公共卫生学 提交时间: 2023-03-29

    摘要: Emerging in December 2019, coronavirus disease 2019 (COVID-19) eventually became a pandemic and posed a tremendous threat to global public health. However, the origins of SARS-CoV-2, the causative agent of COVID-19, remain to be determined. It has been reported that a certain number of the early case clusters had a contact history with the Huanan Seafood Market. Therefore, surveillance of SARS-CoV-2 within the market is of vital importance. Herein, we presented the SARS-CoV-2 detection results of 1380 samples collected from the environment since 1st Jan and animals since 18th Jan within the market in early 2020. By SARS-CoV-2-specific RT-qPCR, 73 environmental samples tested positive for SARS-CoV-2 and three live viruses were successfully isolated. The viruses from the market shared nucleotide identity of 99.99% to 100% with the human isolate HCoV-19/Wuhan/IVDC-HB-01/2019. The A lineage (8782T and 28144C), as the likely ancestral SARS-CoV-2 lineage, was found in an environmental sample. No virus was detected in the animal swabs covering 18 species of animals in the market. The RNA-seq analysis of SARS-CoV-2 positive/negative environmental samples showed the abundance of different vertebrata genera. In summary, this study provided convincing evidence of the prevalence of SARS-CoV-2 in the Huanan Seafood Market during the early stage of COVID-19 outbreak.