Searching for single-particle resonances with the Green’s function method

Single-particle resonances in the continuum are crucial for studies of exotic nuclei.In this study,the Green’s function approach is employed to search for single-particle resonances based on the relativistic-mean-field model.Taking^(120)Sn as an example,we identify singleparticle resonances and determine the energies and widths directly by probing the extrema of the Green’s functions.In contrast to the results found by exploring for the extremum of the density of states proposed in our recent study[Chin.Phys.C,44:084105(2020)],which has proven to be very successful,the same resonances as well as very close energies and widths are obtained.By comparing the Green’s functions plotted in different coordinate space sizes,we also found that the results very slightly depend on the space size.These findings demonstrate that the approach by exploring for the extremum of the Green’s function is also very reliable and effective for identifying resonant states,regardless of whether they are wide or narrow.

Elaborate calibration procedure for cell irradiation at the CAS-LIBB single-particle microbeam

Single-particle microbeam is uniquely capable of precisely delivering a preset number of charged particles to individual cells or sub-cellular targets to be determined in vitro, It is crucial to find a reference point that relates the microbeam＇s location to the microscope＇s plane, and align individual targets at this reference point for cell irradiation. To choose an appropriate reference point, an approach based on analysing the intensity distribution of fluorescence in a thin scintillator excited by traversing particles is newly developed using the CAS-LIBB single-particle microbeam, which features decisive physical signification and sufficient resolution. As its bonus, this on-line analysis provides precise and fast response to the determination of beam profile and potentially optimizes the microbeam quality by further adjusting hardware setup.

The Experiment of Obtaining Micron Beam in the Single-Particle Microbeam Facility of the Institute of Plasma Physics

The Experiments, methods and results of obtaining micron beam in the Microbeam Facility of the Institute of Plasma Physics were discussed in this paper. The H+2 beam was accelerated by the Van de GraafF electrostatic accelerator, and the collimator at the end of the beam line is a 60 μm thick stainless steel chip. And as a result, particle tracks on the solid track probes (CR39 film) etched in the solution of NaOH showed that the beam can go through the collimator with a small aperure (2000, 300, 55, 30, or 10 μm) and 3.5 μm thick vacuum film (Mylar). Besides the CR39 method, the beam was measured by an energy spectrum detector after the 10 μm diameter aperture and the 3.5 μm thick vacuum film too.

Preliminary Study of the CAS-LIBB Single-Particle Microbeam Ⅱ Endstation: Ⅰ. Proposed Multi-Dimensional Quantitative Fluorescence Microscopy

Single-particle microbeam as a powerful tool can open a research field to find answers to many enigmas in radiobiology. A single-particle microbeam facility has been constructed at the Key Laboratory of Ion Beam Bioengineering （LIBB）, Chinese Academy of Sciences （CAS）, China. However there has been less research activities in this field concerning the original process of the interaction between low-energy ions and complicated organisms. To address this challenge, an in situ multi-dimensional quantitative fluorescence microscopy system combined with the CAS-LIBB single-particle microbeam II endstation is proposed. In this article, the rationale, logistics and development of many aspects of the proposed system are discussed.

Investigation of intense sheet electron beam transport using the macroscopic cold-fluid model and the single-particle orbit theory

The focusing and the stable transport of an intense elliptic sheet electron beam in a uniform magnetic field are investigated thoroughly by using the macroscopic cold-fluid model and the single-particle orbit theory.The results indicate that the envelopes and the tilted angles of the sheet electron beam obtained by the two theories are consistent.The single-particle orbit theory is more accurate due to its treatment of the space-charge fields in a rectangular drift tube.The macroscopic cold-fluid model describes the collective transport process in order to provide detailed information about the beam dynamics,such as beam shape,density,and velocity profile.The tilt of the elliptic sheet beam in a uniform magnetic field is carefully studied and demonstrated.The results presented in this paper provide two complete theories for systemically discussing the transport of the sheet beam and are useful for understanding and guiding the practical engineering design of electron optics systems in high power vacuum electronic devices.

Preliminary Study of CAS-LIBB Single-Particle MicrobeamⅡEndstation:Ⅱ.Considerations for Choosing the Right CCD Camera

The proposed multi-dimensional quantitative fluorescence microscopy for the CASLIBB single-particle microbeam II endstation is a CCD-based imaging system. We systematically analyse the theoretical and the practical considerations pertinent to choosing the right CCD camera and unveiling the principles underlying multifarious parameters. Therefore, this analysis can be a valuable tool in scrutinizing each parameter and clarifying proper usage of a scientific CCD camera.

Nano-sized stationary phase packings retained by single-particle frit for microchip liquid chromatography

Modern chromatography is increasingly focused on miniaturization and integration. Compared to conventional liquid chromatography, microfluidic chip liquid chromatography(microchip-LC) has the potential due to its zero-dead volume connection and ease of integration. Nano-sized packings have the potential to significantly enhance separation performance in microchip-LC. However, their application has been hindered by packing difficulties. This study presents a method for packing nano-sized silica particles into a microchannel as the stationary phase. The microchip-LC packed column was prepared by combining the weir and the porous silica single-particle as frit to retain the packing particles. A surface tensionbased single-particle picking technique was established to insert porous single-particle frit into glass microchannels. Additionally, we developed a slurry packing method that utilizes air pressure to inject nano-sized packing into the microchannel. Pressure-driven chromatographic separation was performed using this nano-packed column integrated into a glass microchip. The mixture of four PAHs was successfully separated within just 8 min using a 5 mm separation channel length, achieving high theoretical plates(10~6plates/m). Overall, these findings demonstrate the potential of utilizing nano-sized packings for enhancing chromatographic performance in microchip systems.

Simulation of nanofluid natural convection based on single-particle hydrodynamics in energy-conserving dissipative particle dynamics(eDPD)

In the present study,the nanofliud natural convection is investigated by the energy-conserving dissipative particle dynamics(eDPD)method,where the nanoparticles are considered at the single-particle level.The thermal expansion coefficientβand the viscosityμof the simulated system containing nanoparticles are calculated and found to be in close alignment with the previous simulation results.The single-particle hydrodynamics in e DPD enables simulations of nanofluid natural convection with higher Rayleigh numbers and greater nanoparticle volume fractions.Additionally,this approach is utilized to simulate the nanoparticle distribution during the enhanced heat transfer process in the nanofluid natural convection.The localized aggregation of nanoparticles enhances the heat transfer performance of the nanofluid under specific Rayleigh numbers and nanoparticles volume fractions.

Characterization of lipid-based nanomedicines at the single-particle level

Lipid-based nanomedicines(LBNMs),including liposomes,lipid nanoparticles(LNPs)and extracellular vesicles(EVs),are recognized as one of the most clinically acceptable nano-formulations.However,the bench-to-bedside translation efficiency is far from satisfactory,mainly due to the lack of in-depth understanding of their physical and biochemical attributes at the single-particle level.In this review,we first give a brief introduction of LBNMs,highlighting some milestones and related scientific and clinical achievements in the past several decades,as well as the grand challenges in the characterization of LBNMs.Next,we present an overview of each category of LB-NMs as well as the core properties that largely dictate their biological characteristics and clinical performance,such as size distribution,particle concentration,morphology,drug encapsulation and surface properties.Then,the recent applications of several analytical techniques including electron microscopy,atomic force microscopy,fluorescence microscopy,Raman microscopy,nanoparticle tracking analysis,tunable resistive pulse sensing and flow cytometry on the single-particle characterization of LBNMs are thoroughly discussed.Particularly,the com-parative advantages of the newly developed nano-flow cytometry that enables quantitative analysis of both the physical and biochemical characteristics of LBNMs smaller than 40 nm with high throughput and statistical ro-bustness are emphasized.The overall aim of this review article is to illustrate the importance,challenges and achievements associated with single-particle characterization of LBNMs.

Brake wear-derived particles:Single-particle mass spectral signatures and real-world emissions

Brake wear is an important but unregulated vehicle-related source of atmospheric particulate matter(PM).The single-particle spectral fingerprints of brake wear particles(BWPs)provide essential information for understanding their formation mechanism and atmospheric contributions.Herein,we obtained the single-particle mass spectra of BWPs by combining a brake dynamometer with an online single particle aerosol mass spectrometer and quantified real-world BWP emissions through a tunnel observation in Tianjin,China.The pure BWPs mainly include three distinct types of particles,namely,Bacontaining particles,mineral particles,and carbon-containing particles,accounting for 44.2%,43.4%,and 10.3%of the total BWP number concentration,respectively.The diversified mass spectra indicate complex BWP formation pathways,such as mechanical,phase transition,and chemical processes.Notably,the mass spectra of Ba-containing particles are unique,which allows them to serve as an excellent indicator for estimating ambient BWP concentrations.By evaluating this indicator,we find that approximately 4.0%of the PM in the tunnel could be attributable to brake wear;the real-world fleet-average emission factor of 0.28 mg km
1 veh
1 is consistent with the estimation obtained using the receptor model.The results presented herein can be used to inform assessments of the environmental and health impacts of BWPs to formulate effective emissions control policies.

Dual Rolling Circle Amplification- Assisted Single-Particle Fluorescence Profiling of Exosome Heterogeneity for Discriminating Lung Adenocarcinoma from Pulmonary Nodules

Exosomes secreted by tumor cells carry abundant molecular biomarkers that reflect the status of their originating cells.These tumor-derived exosomes(TDEs)have emerged as attractive diagnostic targets.However,the identification and characterization of highly heterogeneous TDEs remain practically challenging.Here,we report a dual rolling circle amplification(DRCA)-assisted approach for the selective encapsulation of single TDEs for fluorescence microscopic and flow cytometric analysis.TDEs have been targeted by aptamers that recognized their surface tumor marker and exosomal marker CD63,following DRCA that produced entangling polymeric DNA chains,resulting in facile particle enlargement that allows single-particle fluorescence profiling of exosome heterogeneity.We have demonstrated the use of a dual-marker positive ratio for exosome differentiation and applied division and multiplication operations for normalized andmagnified marker heterogeneity analysis.We further applied this assay to distinguish lung adenocarcinoma and pulmonary nodule patients and found an accuracy of 90%.We anticipate promising transformations of this straightforward assay into clinically implantable diagnostic methods.

Single-Particle Tracking for the Quantification of Membrane Protein Dynamics in Living Plant Cells

The plasma membrane is a sophisticated,organized,and highly heterogeneous structure that compartmentalizes cellular processes.To decipher the biological processes involving membrane proteins,it is necessary to analyze their spatiotemporal dynamics.However,it is difficult to directly assess the dynamics and interactions of biomolecules in living cells using traditional biochemical methods.Singleparticle tracking (SPT)methods for imaging and tracking single particles conjugated with fluorescent probes offer an ideal approach to acquire valuable and complementary information about dynamic intracellular processes.SPT can be used to quantitatively monitor the diverse motions of individual particles in living cells.SPT also provides super-spatiotemporal resolution that allows early-stage or rapid response information to be obtained for a better understanding of molecular basis of associated signal transduction processes.More importantly,SPT can be used to detect the motion paths of individual biomolecules in vivo and in situ,thus unveiling the dynamic behavior of the biomolecules that support developmental processes in living cells.In this review,we give an overview of SPT methods,from image acquisition to the detection of single particles,as well as tracking and data analysis.We also discuss recent applications of SPT methods in the field ofplant biology to reveal the complex biological functions of membrane proteins.

Preparation and characterization of NaYF_4:Er^(3+),Tm^(3+)@NaYF_4:Ce^(3+),Tb^(3+) microcrystals with dual-mode emissions at the single-particle level

Under hydrothermal environment,we synthesized lanthanide ions doped sodium yttrium fluoride(NaYF4:Er,Tm@NaYF4:Ce,Tb) luminescent microcrystals via an epitaxial growth technique.The structure and morphology of these microcrystals were examined by SEM,TEM,EDS and XRD measurements.These particles show dual-mode emissions with red upconversion(UC) and green down conversion(DC) as single particles level.The mean length and diameter of these microparticles increase from 0.43 to2.26 μm and from 1.33 to 1.86 μm,respectively.Most interestingly,the photoluminescence properties of NaYF4:Er,Tm@NaYF4:Ce,Tb phosphor crystals are highly dependent on the crystallite size.The microcrystals fluoresce emit dual-mode emissions when they are solid or dispersed in solvents.Benefiting its intensive fluorescence and uniform morphology,these materials hold great potential for security and anti-counterfeiting applications.

Single-particle resonances in a deformed relativistic potential

The positive-parity single-neutron levels in an axially-deformed relativistic quadrupole Woods-Saxon potential are analyzed. Neutron states are obtained as the solutions of the corresponding single-particle Dirac equation, using the coupled-channels method in the coordinate space. The evolution of the levels close to the continuum threshold and, in particular, the occurrence of singleneutron resonant states as the functions of the axial deformation parameter 0 β 0.5, are examined using the eigenphase representation. Calculations are performed for different values of the radius of the potential (R/r 0 ) 3 , corresponding to a variation of the mass number A.

Effects of local matrix environment on the spectroscopic properties of ensemble to single-particle level carbon dots

Carbon dots(CDs), because of their unique properties, are being rapidly developed as important luminescent materials for imaging, sensing, and use in photonic devices. However, most of the reported fundamental properties of the CDs are results of investigations conducted in the solution state, which may be completely different from those conducted in the solid state. In this work, we study the luminescence properties, photostability, and the dynamics of CDs in different matrix environments, from ensemble to the single-particle level. We observed that the properties associated with the emission centers and photostability of CDs were extremely sensitive to the local chemical environment. A better understanding of the dependence of the spectroscopic properties of CDs on the complex local chemical environment is an important step toward finding new ways of controlling the optical properties of CDs and optimizing their use in various applications.

Dissection the endocytic routes of viral capsid proteins-coated upconversion nanoparticles by single-particle tracking

Real-time exploring the cellular endocytic pathway of viral capsid proteins(VCPs)functionalized nanocargos at the single-particle level can provide deep insight into the kinetic information involved in virus infection.In this work,porcine circovirus type 2(PCV2)VCPs with different functions are modified onto the surface of upconversion nanoparticles(VCPs-UCNPs)to investigate the cellular internalization process in real-time.Clathrin-mediated endocytosis is found to be the essential uptake mechanism for these VCPs-UCNPs.Besides,it is verified that P_(1)-UCNPs(PCV2 VCPs with nuclear localization signal,namely P1)can be easily assembled close to the perinuclear area,which is different from that of P_(2)-UCNPs(PCV2 VCPs without nuclear localization signal,namely P_(2)).Interestingly,multistep entry processes are observed.Particularly,confined diffusion is observed during the transmembrane process.The intracellular transport of VCPs-UCNPs is dependent on microtubules toward the cell interior.During this process,P_(1)-UCNPs display increased velocities with active transport,while diffusion much faster around the perinuclear area.But for P_(2)-UCNPs,there are only two phases involved in their endocytosis process.This study presents distinct dynamic mechanisms for the nanocargos with different functions,which would make a useful contribution to the development of robust drug delivery systems.

Quenching of single-particle strengths of carbon isotopes 9-12,14-20C with knockout reactions for incident energies 43–2100 MeV/nucleon

To study the quenching of single-particle strengths of carbon isotopes,a systematic analysis is performed for ^(9-12,14-20) C,with single neutron knockout reactions on Be/C targets,within an energy range from approximately 43 to 2100 MeV/nucleon,using the Glauber model.Incident energies do not show any obvious effect on the resulting values across this wide energy range.The extracted quenching factors are found to be strongly dependent on the proton-neutron asymmetry,which is consistent with the recent analysis of knockout reactions but is inconsistent with the systematics of transfer and quasi-free knockout reactions.

Rapid ultrasensitive monitoring the single-particle surface-enhanced Raman scattering (SERS) using a dark-field microspectroscopy assisted system

The observation of single-particle surface-enhanced Raman scattering(SERS) has generated considerable interest both in the nanomaterials filed and in the single-particle spectroscopy community.It is a challenge to realize rapid,facile,and high throughput SERS at single nanoparticle level.Here,without the complex experimental device and difficult experimental operations,a general single-particle SERS technique has been achieved by using dark-field-assisted surface-enhanced Raman spectroscopy(DFSERS).This advanced method provides in-situ characterization of the chemical reaction performance at single gold nanorod.

Single-particle resonant states with Green’s function method

This study employs the relativistic mean field theory with the Green's function method to study the single-particle resonant states.In contrast to our previous work[Phys.Rev.C,90:054321(2014)],the resonant states are identified by searching for the poles of Green's function or the extremes of the density of states.This new approach is highly effective for all kinds of resonant states,no matter whether they are broad or narrow.The dependence on the space size for the resonant energies,widths,and the density distributions in the coordinate space has been checked and was found to be very stable.Taking ^120Sn as an example,four new broad resonant states 2g7/2,2g9/2,2h11/2,and 1j13/2 were observed,and the accuracy for the width of the very narrow resonant state 1h9/2 was highly improved to 1×10^−8 MeV.Further,our results are very close to those obtained using the complex momentum representation method and the complex scaling method.

Quantifying Contribution of Recycled Moisture to Precipitation in Temperate Glacier Region,Southeastern Tibetan Plateau,China

Recycled moisture is an important indicator of the renewal capacity of regional water resources.Due to the existence of Yulong Snow Mountain,Lijiang in Yunnan Province,southeast of the Qinghai-Tibet Plateau,China,is the closest ocean glacier area to the equator in Eurasia.Daily precipitation samples were collected from 2017 to 2018 in Lijiang to quantify the effect of sub-cloud evaporation and recycled moisture on precipitation combined with the d-excess model during monsoon and non-monsoon periods.The results indicated that the d-excess values of precipitation fluctuated between–35.6‰and 16.0‰,with an arithmetic mean of 3.5‰.The local meteoric water line(LMWL)wasδD=7.91δ^(18)O+2.50,with a slope slightly lower than the global meteoric water line(GMWL).Subcloud evaporation was higher during the non-monsoon season than during the monsoon season.It tended to peak in March and was primarily influenced by the relative humidity.The source of the water vapour affected the proportion of recycled moisture.According to the results of the Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)model,the main sources of water vapour in Lijiang area during the monsoon period were the southwest and southeast monsoons.During the non-monsoon period,water vapour was transported by a southwesterly flow.The recycled moisture in Lijiang area between March and October 2017 was 10.62%.Large variations were observed between the monsoon and non-monsoon seasons,with values of 5.48%and 25.65%,respectively.These differences were primarily attributed to variations in the advection of water vapour.The recycled moisture has played a supplementary role in the precipitation of Lijiang area.