Single State Research Articles

Structure-guided engineering and molecular simulations to design a potent monoclonal antibody to target aP2 antigen for adaptive immune response instigation against type 2 diabetes.

Diabetes mellitus (DM) is recognized as one of the oldest chronic diseases and has become a significant public health issue, necessitating innovative therapeutic strategies to enhance patient outcomes. Traditional treatments have provided limited success, highlighting the need for novel approaches in managing this complex disease. In our study, we employed graph signature-based methodologies in conjunction with molecular simulation and free energy calculations. The objective was to engineer the CA33 monoclonal antibody for effective targeting of the aP2 antigen, aiming to elicit a potent immune response. This approach involved screening a mutational landscape comprising 57 mutants to identify modifications that yield significant enhancements in binding efficacy and stability. Analysis of the mutational landscape revealed that only five substitutions resulted in noteworthy improvements. Among these, mutations T94M, A96E, A96Q, and T94W were identified through molecular docking experiments to exhibit higher docking scores compared to the wild-type. Further validation was provided by calculating the dissociation constant (KD), which showed a similar trend in favor of these mutations. Molecular simulation analyses highlighted T94M as the most stable complex, with reduced internal fluctuations upon binding. Principal components analysis (PCA) indicated that both the wild-type and T94M mutant displayed similar patterns of constrained and restricted motion across principal components. The free energy landscape analysis underscored a single metastable state for all complexes, indicating limited structural variability and potential for high therapeutic efficacy against aP2. Total binding free energy (TBE) calculations further supported the superior performance of the T94M mutation, with TBE values demonstrating the enhanced binding affinity of selected mutants over the wild-type. Our findings suggest that the T94M substitution, along with other identified mutations, significantly enhances the therapeutic potential of the CA33 antibody against DM by improving its binding affinity and stability. These results not only contribute to a deeper understanding of antibody-antigen interactions in the context of DM but also provide a valuable framework for the rational design of antibodies aimed at targeting this disease more effectively.

Intramolecular Heteroatom and Styryl Diels-Alder Reactions, Asymmetric Cycloadditions of Chiral 3-Phenylallyl Maleic Esters.

Polycyclic aryl naphthalene and tetralin dihydro arylnaphthalene lactone lignans possess anticancer and antibiotic activity. Related furo[3,4-c]pyranones, typified by the sequester-terpenoid isobolivianine, show similar antiproliferative bioactivity. Efficient syntheses of compounds featuring these polycyclic cores have proven challenging due to low yields and poor stereoselectivity. We report the synthesis of chiral cinnamyl but-2-enanoates and 3,3-diphenylallyl-but-2-enoates 1 as new Diels-Alder substrates. These compounds undergo [4 + 2]-cycloadditions to give furo[3,4-c]pyranones 2 in good yield (70%) and diastereoselectivity (7:1), together with naphthyl 3 and dihydronaphthyl tetralins 4 as minor products. Molecular structures and stereochemistries of the major products were verified using X-ray diffraction. Density functional theory calculations revealed that the cycloaddition process involves a bispericyclic/ambimodal process where there is a single transition state that leads to both intramolecular styryl Diels-Alder (ISDA) 3, 4 and intramolecular hetero Diels-Alder (IHDA) cycloadducts 2. With the elevated temperature conditions after cycloaddition, the resulting ISDA cycloadduct either undergoes [3,3]-sigmatropic rearrangement to the more stable major IHDA product or aromatization leading to the phenyltetralin.

Experimental study of liquid aluminum droplet breakup characteristics based on a Drop-on-demand (DOD) magnetohydrodynamic actuation

In magnetohydrodynamic (MHD) drop-on-demand (DOD) actuation, Lorentz force generated in different excitation stages are exerted on the liquid metal jet to form a "push-pull" mechanism, which is crucial for generating accurate and repeatable metal droplets. In this study, the important parameters of the excitation current waveform in the magnetohydrodynamic (MHD) process, including the influence of the excitation voltage pulse width ratio and current amplitude on the velocity, energy, volume, and breakup length of aluminum droplets are studied. The conversion process of surface energy and kinetic energy during the formation and fall stage of liquid droplets is analyzed. The results show that the negative and positive excitation voltage pulse width ratio of the MHD pump has a significant effect on the droplet velocity, breakup time, size, and sphericity. The amplitude of the excitation current and Hartmann number has a significant impact on the generation of stable droplets. The results show that the single droplet ejection state can be achieved within the Ha number between 319.5 and 391.1. As the Ha number increases, the volume, length, kinetic energy and surface energy of the droplets at breakup time also increase. The size of droplets can be adjusted by changing the amplitude of excitation waveform.

Overlap structure and free energy fluctuations in short-range spin glasses

We investigate scenarios in which the low-temperature phase of short-range spin glasses comprises thermodynamic states which are nontrivial mixtures of multiple incongruent pure state pairs. We construct a new kind of metastate supported on Gibbs states whose edge overlap values with a reference state fall within a specified range. Using this metastate we show that, in any dimension, the variance of free energy difference fluctuations between pure states within a single mixed Gibbs state with multiple edge overlap values diverges linearly with the volume. We discuss some implications of these results.

Chemical synthesis of Mn–Zn magnetic ferrite nanoparticles: Effect of secondary phase on extrinsic magnetic properties of Mn–Zn ferrite nanoparticles

This paper presents a comprehensive investigation of the magnetic properties of co-precipitated MnxZn1–xFe2O4 nanoferrites, where x takes the values of 0.5, 0.6, and 0.7. X-ray diffraction patterns indicated the presence of spinel phase. However, the ferrite composition x = 0.6 contains little trace of secondary phase α-Fe2O3. The occurrence of cation redistribution in the current ferrite samples can be concluded from the deviation of oxygen position parameter (U) to that of optimum value (0.375). The bond angles facilitate the reduction of the A–B interaction and the increase of the B–B interaction. With the substitution of Mn2+ ions, the saturation magnetization (Ms) exhibits both drops and increases whereas the coercivity (Hc) consistently declines. The ferrite composition x = 0.7 exhibits the maximum value of Ms and is equal to 27.9 emu/g. The blocking temperature (TB) rises in proportion to the degree of Mn2+ ion doping. The observation of quadruple doublets in the Mӧssbauer spectra indicates that the ferrite nanoparticles exist in single domain state exhibiting the quadruple interactions. The range of isomer shift (δ) 0.199–0.267 mm/s indicates the existence of exclusively high spin Fe3+ ions. Two paramagnetic doublets are anticipated to exist as a result of the core and shell of present ferrite nanoparticles. In the core-shell morphology of nanoparticles, the core is characterized by larger quadruple splitting (Δ) while the shell is characterized by smaller Δ. The results are integrated in terms of magnetocrystalline anisotropy and secondary phase presuming the core-shell structure of nanoparticles.

Efficient semi-analytic method for single tooth contact analysis of loaded spiral bevel gears

Accurately and fast calculation of single tooth load contact state of a gear pair is the basis for accurate calculation of multi-tooth load contact analysis. Therefore, this study proposed a semi-analytical quick single tooth load tooth contact analysis (Q-SLTCA) method. First, the ease-off tooth contact analysis (ease-off TCA) method was established, and a numerically stable initial contact stress distribution and contact ellipse analytical model was derived. Then, considering the influence of edge contact, the real-time division method of gear tooth slice was derived. Based on this, the equivalent principle of contact elliptical node and the load correction strategy were innovatively proposed. Then, the calculation method of the meshing characteristics of the tooth slice was established by coupling the boundary element method (BEM) with the equivalent cylindrical Hertz contact theory. The bending deformation, tooth root stress distribution, contact stress, contact deformation and meshing stiffness of the tooth slice were analyzed and calculated, and the instantaneous meshing stiffness of the single tooth was determined by combining the parallel method of the gear tooth stiffness. Finally, a single-tooth finite element method (FEM) meshing model was created for comparison with the method in this study, which verified the calculation accuracy and efficiency of the proposed method. This method can be easily developed into a quick multi-tooth load contact analysis algorithm, which can provide a new method for gear tooth crack and failure analysis.

ABOUT THE HISTORICAL PREREQUISITES OF THE FORMATION OF PUBLIC SAFETY CENTERS IN THE CONDITIONS OF UKRAINE

The purpose of publication is analysis of literary and archival sources in order to establish the historical stages of the formation of the Service of Emergency Situations, ascertaining of its main tasks, and mainly to identify the features of the structural and functional organization of historical prototypes for modern centers of public safety. In general, the process of formation and development of the fire protection system, its transformation into an emergency service has so deep roots, starting with the laws of the state Kievan Rus until today. An analysis of the development of the fire service on the example of separate cities of Ukraine showed, that in the process of its development it was placed in buildings of sacred (churches) and administrative (town halls) purpose. Later, a single network of a separate type of architectural objects was gradually formed (watchtowers, fire stations), which were expanding according to the development of the city. Buildings where fire service personnel were placed, contained all the necessary means for notifying the population, quick reaction, and counter measuring in the case of an emergency situation and updated with the advent of modern technologies. It should be noted separately that during certain periods of fire protection development this service was located together with the police service, which is an important prerequisite for the formation of a structural and functional organization of modern centers of public safety. Also noteworthy is the fact that the civilian population was involved in fire protection on a voluntary basis. In general, we can say that during the development of the fire service of Ukraine prototypes of networks of public safety centers in cities already existed, but they were not considered as a separate typological group of architectural and urban planning objects. Historically, it happened that the fire service, and in the 20th century - also the civil defense service (which initially was developing separately), during the last decade were united into a single state structure – SESU. The main stages (periods) of the development of which begin with the historical period (before 1494) and end with the modern period of development (arrangement of SESU) from 2012 to the present time.

Areas of stability of the dynamic equilibrium points of a chemical reactor

Abstract This article develops a method for determining the areas of attraction of trajectories by stable points of dynamic equilibrium. This method is based on determining a line separating these areas. In the case of n-fold equilibrium states, there are a maximum of (n + 1)/2 regions of attraction. This is the maximum number of stable states. It may also happen that none of the states are stable and then there will not be any area of attraction. The number of all states n is odd. In the case of single stable states, we are dealing with one unlimited region of attraction. In the case of three-fold equilibrium states, two of which are stable, there are two regions of attraction, etc. In this study, the case of three-fold dynamic equilibrium states of a chemical tank reactor is considered.

Binomial Uncertainty in Molecular Dynamics-Based Reactions Analysis.

Molecular Dynamics-based reaction analysis is an indispensable tool for studying processes defying the transition-state theory (TST), where the product ratios do not follow energies of transition states. The main class of such processes is ambimodal reactions, which have a post-transition-state bifurcation, so that several products form via a single transition state. Multiple runs of molecular dynamics allow one to sample the space of possibilities and ultimately predict the product ratio without relying on TST; however, no techniques for estimating the reliability of the prediction were proposed so far. Here we show that dynamics runs follow the same rules as die rolls, which paves a simple way for estimating their uncertainty and, accordingly, the number of runs necessary to achieve the required accuracy. Remarkably, we find that the majority of such studies carried out in the last 5 years use far too few runs, so that the product ratios predicted in them can be off by >50% in more than 50% of cases.

Fe-N-C core–shell catalysts with single low-spin Fe(II)-N4 species for oxygen reduction reaction and high-performance proton exchange membrane fuel cells

Fe-N-doped carbon materials (Fe-N-C) are promising candidates for oxygen reduction reaction (ORR) relative to Pt-based catalysts in proton exchange membrane fuel cells (PEMFCs). However, the intrinsic contributions of Fe-N4 moiety with different chemical/spin states (e.g. D1, D2, D3) to ORR are unclear since various states coexist inevitably. In the present work, Fe-N-C core–shell nanocatalyst with single low-spin Fe(II)-N4 species (D1) is synthesized and identified with ex-situ ultralow temperature Mössbauer spectroscopy (T = 1.6 K) that could essentially differentiate various Fe-N4 states and invisible Fe-O species. By quantifying with CO-pulse chemisorption, site density and turnover frequency of Fe-N-C catalysts reach 2.4 × 1019 site g−1 and 23 e site−1 s−1 during the ORR, respectively. Half-wave potential (0.915 VRHE) of the Fe-N-C catalyst is more positive (approximately 54 mV) than that of Pt/C. Moreover, we observe that the performance of PEMFCs on Fe-N-C almost achieves the 2025 target of the US Department of Energy by demonstrating a current density of 1.037 A cm−2 combined with the peak power density of 0.685 W cm−2, suggesting the critical role of Fe(II)-N4 site (D1). After 500 h of running, PEMFCs still deliver a power density of 1.26 W cm−2 at 1.0 bar H2-O2. An unexpected rate-determining step is figured out by isotopic labelling experiment and theoretical calculation. This work not only offers valuable insights regarding the intrinsic contribution of Fe-N4 with a single spin state to alkaline/acidic ORR, but also provides great opportunities for developing high-performance stable PEMFCs.

Facile one-step solid-state synthesis of CuO nanoparticles finely decorated over carbon sheets for improved OER activity

Renewable energy storage and conversion in electrochemical fuel cells require highly efficient and cost-effective noble metal free electrocatalysts for oxygen evolution reaction (OER). Downscaling of a material to nanoscale morphology can lead to enhancement in its surface activities affecting its physical and chemical properties which can well serve the purpose. In lieu to this, it could be one of the first reports to tune the morphology of CuO particles to 10–25 nm finely trapped inside non-graphitic carbon sheets using a novel single step solid state reaction. XRD, SEM, TEM, XPS, and Raman analyses confirm the structural and morphological attributes. The synergistic effect from carbon and copper oxide resulted in the attainment of best-in-class electrode material for oxygen evolution reaction (OER). The as-prepared CuO/C shows an excellent OER activity with a low overpotential of 454 mV (vs. Ag/AgCl) at a current density of 10 mA cm−2 with a low Tafel slope of 74.9 mV dec−1. The amount of carbon is optimized to get optimal performance from the CuO nanopowder.

Assessing the effect of cardiovascular disease on work productivity and financial loss among school teachers in Peninsular Malaysia: a nested case-control study.

School teachers may have an increased risk of cardiovascular disease (CVD), potentially affecting their work productivity. However, limited data exists on the impact of CVD on teachers' productivity in Malaysia. Our objectives were to assess work productivity loss (absenteeism and presenteeism) as well as to determine the associated annual monetary loss among school teachers who experienced incident CVD in Peninsular Malaysia. We adopted a nested case-control design within a cohort of school teachers. Working teachers from six states of Peninsular Malaysia, and had experienced incident CVD before a right-censored date (31st December 2021) were defined as cases. Incident CVD was operationally defined as the development of non-fatal acute coronary syndrome (ACS), stroke, congestive cardiac failure, deep vein thrombosis or peripheral arterial disease before the censored date. Controls were working teachers who did not acquire an incident CVD before the similar right-censored date. All controls were randomly selected, with a ratio of one case to four controls, from among the working teachers in one of the states in Peninsular Malaysia. We used a shortened version of the Malay-validated World Health Organization-Health and Work Performance Questionnaire (WHO-HPQ) to estimate the workplace productivity effect among teachers with incident CVD (cases). The same questionnaire was distributed to teachers in a single state of Peninsular Malaysia who did not experience incident CVD (controls). Absenteeism, presenteeism and annual monetary loss were computed based on the scoring rules in the WHO-HPQ. Analysis of covariance was performed with covariate adjustment using propensity scores. The bootstrapping method was applied to obtain better estimates of marginal mean differences, along with standard errors (SE) and appropriate effect sizes. We recruited 48 cases (baseline mean age = 42.4 years old, 54.2% females) and 192 randomly selected controls (baseline mean age = 36.2 years old, 99.0% females). The majority of the cases had ACS (73.9%). No significant difference was observed in absenteeism between cases and controls. The mean self-rated job performance score was lower for cases (7.63, SE = 0.21) compared to controls (8.60, SE = 0.10). Marginal mean scores of absolute presenteeism among cases (76.30) were lower (p<0.05, eta squared = 0.075) than controls (85.97). The marginal mean annual cost of presenteeism was higher in cases (MYR 21,237.52) compared to controls (MYR 12,089.74) (p<0.05, eta squared = 0.082). Absolute presenteeism was lower among school teachers who experienced incident CVD and the annual cost of presenteeism was substantial. Implementing supportive work strategies in school settings is recommended to increase absolute presenteeism, which can lead to a reduction in the annual cost of presenteeism among teachers experiencing incident CVD.

Linear optical properties of organic microcavity polaritons with non-Markovian quantum state diffusion

Abstract Hybridisation of the cavity modes and the excitons to polariton states together with the coupling to the vibrational modes determine the linear optical properties of organic semiconductors in microcavities. In this article we compute the refractive index for such system using the Holstein–Tavis–Cummings model and determine then the linear optical properties using the transfer matrix method. We first extract the parameters for the exciton in our model from fitting to experimentally measured absorption of a 2,7-bis[9,9-di(4-methylphenyl)-fluoren-2-yl]-9,9-di(4-methylphenyl) fluorene (TDAF) molecular thin film. Then we compute the reflectivity of such a thin film in a metal clad microcavity system by including the dispersive microcavity mode to the model. We compute susceptibility of the model systems evolving just a single state vector by using the non-Markovian quantum state diffusion. The computed location and height of the lower and upper polaritons agree with the experiment within the estimated errorbars for small angles ( ≤ 30 ° ) $(\le 30{}^{\circ})$ . For larger angles the location of the polariton resonances are within the estimated error.

Statewide efforts to address the opioid epidemic: Results from a national survey of single state agencies

BackgroundSingle State Agencies (SSAs) are at the forefront of efforts to address the nation's opioid epidemic, responsible for allocating billions of dollars in federal, state, and local funds to ensure service quality, promote best practices, and expand access to care. Federal expenditures to SSAs have more than tripled since the early years of the epidemic, yet, it is unclear what initiatives SSAs have undertaken to address the crisis and how they are financing these efforts. MethodsThis study used data from an internet-based survey of SSAs, conducted by the University of Chicago Survey Lab from January to December 2021 (response rate of 94 %). The survey included a set of 14 items identifying statewide efforts to address the opioid epidemic and six funding sources. We calculated the percentage of SSAs that supported each statewide effort and the percentage of SSAs reporting use of each source of funding across the 14 statewide efforts. ResultsTreatment of opioid-related overdose figured most prominently among statewide efforts, with all SSAs providing funding for naloxone distribution and all but one SSA supporting naloxone training. Recovery support services, Project ECHO, and Hub and Spoke models were supported by the vast majority of SSAs. Statewide efforts related to expanding access to medications for opioid use disorder (MOUD) received somewhat less support, with 45 % of SSAs supporting mobile methadone/MOUD clinics/programs and 70 % supporting buprenorphine in emergency departments. A relatively low proportion of SSAs (54 %) provided support for syringe services programs. State Opioid Response (SOR) funds were the most common funding source reported by SSAs (57 % of SSAs), followed by block grant funds (19 %) and other state funding (15 %). ConclusionResults highlight a range of SSA efforts to address the nation's opioid epidemic. Limited adoption of efforts to expand access to MOUD and harm reduction services may represent missed opportunities. The uncertainty over reauthorization of the SOR grant post-2025 also raises concerns over sustainability of funding for many of these statewide initiatives.

Anisotropic Colloidal Particles by Molecular Self‐Assembly: Synthesis and Application

AbstractAnisotropic colloidal particles have attracted great attention over the past few decades because of their significant properties that differ from isotropic particles. Molecular self‐assembly provides the possibility to design and construct anisotropic colloidal particles from the single‐molecule level, and molecular assemblies can both inherit the properties of molecules in single states and integrate the functions of molecules in collective states, which has attracted great interest to researchers. Even in recent years, the self‐assembly strategy of anisotropic colloidal particles has been greatly developed. This review article briefly summarizes the research progress of molecules from small molecules, block copolymers and homopolymers to anisotropic particles, including their self‐assembly strategies and applications. Finally, we discuss the remaining challenges of this topic and we expect that by manipulating the design of diverse molecules/polymers, anisotropic colloidal particles can evolve into a new era.

Pseudospin symmetry in resonant states in deformed nucleus 154Dy

It is known that pseudospin symmetry plays a crucial role in formation of many physical phenomena. By combining the relativistic mean field theory with the complex momentum representation method, the pseudospin symmetry in the single particle resonant states in the deformed nucleus [Formula: see text]Dy is investigated through the energy and width splittings, the quadrupole deformation parameter, the radial density distributions and occupation probabilities of the pseudospin doublets. Near the continuum threshold, the pseudospin symmetry is well reserved in both bound and resonant states. The energy and width splittings of pseudospin doublets in resonant states exhibit correlations with the deformation and quantum numbers. The good pseudospin symmetry is expected with lower pseudo-orbital angular momentum projection [Formula: see text] and the main quantum number N. In general, an increase in deformation tends to weaken the quality of the pseudospin symmetry. The understanding of the evolution of the pseudospin doublets in the resonant states has been deepened by studying the pseudospin symmetry in the deformed nuclei.

Transcriptional characterization of iPSC-derived microglia as a model for therapeutic development in neurodegeneration

Microglia are the resident immune cells in the brain that play a key role in driving neuroinflammation, a hallmark of neurodegenerative disorders. Inducible microglia-like cells have been developed as an in vitro platform for molecular and therapeutic hypothesis generation and testing. However, there has been no systematic assessment of similarity of these cells to primary human microglia along with their responsiveness to external cues expected of primary cells in the brain. In this study, we performed transcriptional characterization of commercially available human inducible pluripotent stem cell (iPSC)-derived microglia-like (iMGL) cells by bulk and single cell RNA sequencing to assess their similarity with primary human microglia. To evaluate their stimulation responsiveness, iMGL cells were treated with Liver X Receptor (LXR) pathway agonists and their transcriptional responses characterized by bulk and single cell RNA sequencing. Bulk transcriptome analyses demonstrate that iMGL cells have a similar overall expression profile to freshly isolated human primary microglia and express many key microglial transcription factors and functional and disease-associated genes. Notably, at the single-cell level, iMGL cells exhibit distinct transcriptional subpopulations, representing both homeostatic and activated states present in normal and diseased primary microglia. Treatment of iMGL cells with LXR pathway agonists induces robust transcriptional changes in lipid metabolism and cell cycle at the bulk level. At the single cell level, we observe heterogeneity in responses between cell subpopulations in homeostatic and activated states and deconvolute bulk expression changes into their corresponding single cell states. In summary, our results demonstrate that iMGL cells exhibit a complex transcriptional profile and responsiveness, reminiscent of in vivo microglia, and thus represent a promising model system for therapeutic development in neurodegeneration.

Buffeting Characteristics of a Long-Span Cable-Stayed Bridge Crossing a Deep Canyon during Erection: Response Evaluation and Vibration Control

The stiffness of a long-span cable-stayed bridge under construction may be much lower than that observed in service, making it more susceptible to wind effects, especially for a bridge designed using high piers crossing a deep canyon. To study the buffeting characteristics of such cable-stayed bridges under construction, a long-span cable-stayed bridge (the main span is 575 m) is taken as the engineering background. In this study, the buffeting responses and vibration countermeasures at three different construction states were systematically studied using time-domain analysis. It was found that the buffeting response enlarges with an increase in the wind attack angle. The RMS values of the vertical buffeting of the bridge deck end are relatively greater at the maximum double cantilever construction state and maximum single cantilever state. At maximum double cantilever construction state, the traditional wind-resistant cable connecting the bridge deck end to the bridge pile cap significantly reduces the vertical buffeting response, while the suppression effect on lateral and torsional buffeting is limited. When the bridge deck nears completion, wind-resistant cables installed at both cantilever ending in the ‘soft connection’ method would effectively suppress the vertical, lateral, and torsional buffeting. The suppression effect of cross-arranged wind-resistant cables is superior to that of the parallel arrangement. It is recommended that a reasonable wind-resistant cable layout scheme according to different construction conditions is selected.

Theoretical and simulation investigation of practical QKD for both BB84 and SARG04 protocols

In this paper, we provide a simple approach for determining the rate of secure key production when single-photon and two-photon pulses are used to generate the secure key. For both BB84 and SARG04, we offer estimation and optimization of decoy-state parameters for a single decoy state protocol and two decoy state protocols. This method can be used to determine the lower bound on the fraction of single-photon counts ([Formula: see text]), the fraction of two-photon counts ([Formula: see text]), the upper bound on the QBER of single-photon pulses ([Formula: see text]), the upper bound on the QBER of two-photon pulses ([Formula: see text]), and the lower bound on the key generation rate for both BB84 and SARG04. Due to the limited data size in real-world experiments, we estimate the statistical fluctuations of several parameters, including the gain and QBER of the signal state, as well as the gain and QBER of the decoy state, which are used to estimate the lower bound of key generation rate. We propose formulae that specify the optimal decoy and signal state percentages and intensities. Then we can determine the maximum and optimal key generation rate. For both SARG04 and BB84, we simulated a free space-based QKD system using our decoy state strategy. The simulation results show that free space-based QKD systems that use the suggested approach for BB84 can achieve a higher secret key rate and a greater safe distance than SARG04-based systems.

Resolved Raman sideband cooling of a single optically trapped cesium atom.

We developed a resolved Raman sideband cooling scheme that can efficiently prepare a single optically trapped cesium (Cs) atom in its motional ground states. A two-photon Raman process between two outermost Zeeman sublevels in a single hyperfine state is applied to reduce the phonon number. Our scheme is less sensitive to the variation in the magnetic field than the commonly used scheme where the two outermost Zeeman sublevels belonging to the two separate ground hyperfine states are taken. Fast optical pumping with less spontaneous emission guarantees the efficiency of the cooling process. After cooling for 50 ms, 82% of the Cs atoms populate their three-dimensional ground states. Our scheme improves the long-term stability of Raman sideband cooling in the presence of magnetic field drift and is thus suitable for cooling other trapped atoms or ions with abundant magnetic sublevels.