Experimental Limits on Solar Reflected Dark Matter with a New Approach on Accelerated-Dark-Matter-Electron Analysis in Semiconductors.

Recently a dark matter-electron (DM-electron) paradigm has drawn much attention. Models beyond the standard halo model describing DM accelerated by high energy celestial bodies are under intense examination as well. In this Letter, a velocity components analysis (VCA) method dedicated to swift analysis of accelerated DM-electron interactions via semiconductor detectors is proposed and the first HPGe detector-based accelerated DM-electron analysis is realized. Utilizing the method, the first germanium based constraint on sub-GeV solar reflected DM-electron interaction is presented with the 205.4 kg·day dataset from the CDEX-10 experiment. In the heavy mediator scenario, our result excels in the mass range of 5-15 keV/c^{2}, achieving a 3 orders of magnitude improvement comparing with previous semiconductor experiments. In the light mediator scenario, the strongest laboratory constraint for DM lighter than 0.1 MeV/c^{2} is presented. The result proves the feasibility and demonstrates the vast potential of the VCA technique in future accelerated DM-electron analyses with semiconductor detectors.

Fe3O4nanoparticles anchored on carbon nanotubes as high-performance anodes for asymmetric supercapacitors.

Fe3O4/CNT composites are synthesized with ethylene glycol as solvent by a one-step solvothermal method and used as anode materials for asymmetric supercapacitors (ASC). An appropriate amount of water in ethylene glycol can accelerate the formation of Fe3O4and reduce the average size of Fe3O4to around 20 nm. However, spherical Fe3O4particles larger than 100 nm will form in pure ethylene glycol for long reaction time. The Fe3O4/CNT composite with small Fe3O4nanoparticles exhibits a high specific surface area, promoted electron transfer ability, as well as a high utilization rate of active materials. The optimized electrode shows a high specific capacity of 689 C g-1at 1 A g-1, and remains 443 C g-1at 10 A g-1. The inferior long-term cycling stability is due to the phase transition of Fe3O4and a reductive effect to form metallic Fe. An ASC using Fe3O4/CNT and NiCoO2/C composites as anode and cathode, respectively, delivers a high energy density of 58.1 Wh kg-1at a power density of 1007 W kg-1in a voltage window of 1.67 V and has a capacity retention of 63% after 5000 cycles. The self-discharge behavior of the ASC is also investigated.

Uniform Fe2 O3 Nanospheres Anchored on Multilayer Graphene as Anode Materials for High-Rate Ni-Fe Batteries.

Ni-Fe battery is one of prospective aqueous alkaline batteries due to its high safety, eco-friendliness and cost-effectiveness. However, the electrochemical performance of Fe-based anodes is limited due to the particle aggregation and low electric conductivity. In this work, iron powder is used as a precursor in a chemical bath deposition method. By optimizing the concentration of HNO3 , a balanced dissolution-crystallization process is achieved to obtain uniform Fe2 O3 nanospheres in size between 60 and 90 nm, which are separately anchored on ultrasonically prepared multilayer graphene (MLG). This composite delivers specific discharge capacities of 191.1 and 160.8 mAh g-1 at the current densities of 2 and 10 A g-1 , respectively. A Ni-Fe battery with the as-prepared Fe2 O3 /MLG as anode and Ni(OH)2 /MLG as cathode exhibits an energy density of 69.5 Wh kg-1 at a high power density of 3931.6 W kg-1 .

Controllable reduction of NiCoO2@NiCo core-shell nanospheres on CNTs for high-performance electrochemical energy storage.

The performances of energy storage devices are strongly dependent on the electrode materials. Owing to the high theoretical capacity, NiCoO2 is a promising transition metal oxide for supercapacitors. Despite many efforts have been devoted, it still lacks of effective methods to overcome its shortcomings such as low conductivity and poor stability, in order to achieve its theoretical capacity. Herein, utilizing the thermal reducibility of trisodium citrate and its hydrolyzate, a series of NiCoO2@NiCo/CNT ternary composites in which NiCoO2@NiCo core-shell nanospheres deposited on CNT surface with adjustable metal contents are synthesized. Benefiting from the enhanced synergistic effect of both metallic core and CNTs, the optimized composite exhibits an extremely high specific capacitance (2660 F g-1 at 1 A g-1, the effective specific capacitance of the loaded metal oxide is 4199 F g-1, close to the theoretical value), an excellent rate performance and stability, when the metal content is about 37%. After depolarized calculation, the energy storage mechanism of the composite is reasonably analyzed. By controlling the contents of hexamethylenetetramine, trisodium citrate and CNTs in the reactant, the roles of them are distinguished. This study reveals an efficient novel strategy for transition metal oxides to maximize the electrochemical performances.

Measurement of the

The ^{18}O(α,γ)^{22}Ne reaction is critical for AGB star nucleosynthesis due to its connection to the abundances of several key isotopes, such as ^{21}Ne and ^{22}Ne. However, the ambiguous resonance energy and spin-parity of the dominant 470 keV resonance leads to substantial uncertainty in the ^{18}O(α,γ)^{22}Ne reaction rate for the temperature of interest. We have measured the resonance energies and strengths of the low-energy resonances in ^{18}O(α,γ)^{22}Ne at the Jinping Underground Nuclear Astrophysics experimental facility (JUNA) with improved precision. The key 470 keV resonance energy has been measured to be E_{α}=474.0±1.1 keV, with such high precision achieved for the first time. The spin-parity of this resonance state is determined to be 1^{-}, removing discrepancies in the resonance strengths in earlier studies. The results significantly improve the precision of the ^{18}O(α,γ)^{22}Ne reaction rates by up to about 10 times compared with the previous data at typical AGB temperatures of 0.1-0.3 GK. We demonstrate that such improvement leads to precise ^{21}Ne abundance predictions, with an impact on probing the origin of meteoritic stardust SiC grains from AGB stars.

Modeling the charge collection efficiency in the Li-diffused inactive layer of P-type high purity germanium detector.

A model of the Li-diffused inactive layer in P-type high purity germanium detectors is built to describe the transportation of charge carriers and calculate the charge collection efficiency therein. The model is applied to calculate charge collection efficiency of a P-type point-contact germanium detector used in rare event physics experiments and validated in another P-type semi-planar germanium detector. The calculated charge collection efficiency curves are well consistent with measurements for both detectors. Effects of the Li doping processes on the charge collection efficiency are discussed based on the model. This model can be easily extended to other P-type germanium detectors, for instance, the P-type broad-energy Ge detector, and the P-type inverted-coaxial point-contact detector.

Constraints on Sub-GeV Dark Matter-Electron Scattering from the CDEX-10 Experiment.

We present improved germanium-based constraints on sub-GeV dark matter via dark matter-electron (χ-e) scattering using the 205.4 kg·day dataset from the CDEX-10 experiment. Using a novel calculation technique, we attain predicted χ-e scattering spectra observable in high-purity germanium detectors. In the heavy mediator scenario, our results achieve 3 orders of magnitude of improvement for m_{χ} larger than 80 MeV/c^{2} compared to previous germanium-based χ-e results. We also present the most stringent χ-e cross-section limit to date among experiments using solid-state detectors for m_{χ} larger than 90 MeV/c^{2} with heavy mediators and m_{χ} larger than 100 MeV/c^{2} with electric dipole coupling. The result proves the feasibility and demonstrates the vast potential of a new χ-e detection method with high-purity germanium detectors in ultralow radioactive background.

Exotic Dark Matter Search with the CDEX-10 Experiment at China's Jinping Underground Laboratory.

A search for exotic dark matter (DM) in the sub-GeV mass range has been conducted using 205 kg day data taken from a p-type point contact germanium detector of the CDEX-10 experiment at China's Jinping underground laboratory. New low-mass dark matter searching channels, neutral current fermionic DM absorption (χ+A→ν+A) and DM-nucleus 3→2 scattering (χ+χ+A→ϕ+A), have been analyzed with an energy threshold of 160 eVee. No significant signal was found; thus new limits on the DM-nucleon interaction cross section are set for both models at the sub-GeV DM mass region. A cross section limit for the fermionic DM absorption is set to be 2.5×10^{-46} cm^{2} (90% C.L.) at DM mass of 10 MeV/c^{2}. For the DM-nucleus 3→2 scattering scenario, limits are extended to DM mass of 5 and 14 MeV/c^{2} for the massless dark photon and bound DM final state, respectively.

NiCoO2 and polypyrrole decorated three-dimensional carbon nanofiber network with coaxial cable-like structure for high-performance supercapacitors.

Designing optimized nano-sized architecture is a promising approach to prepare high-performance electrode materials for supercapacitors. In this work, a hierarchical multi-shelled structure has been successfully synthesized, which consists of a 3D carbon nanofiber network as a supporting scaffold prepared by carbonization of aramid nanofiber aerogel, an intermediate polypyrrole (PPy) bonding layer and a NiCoO2 outer shell, just like a coaxial cable in the structure. The intermediate PPy layer facilitates the uniform deposition of NiCoO2 by providing more anchor sites, and enhances the electrical contact between carbon nanofiber network and NiCoO2 shell due to its high conductivity and good compatibility with two different substances. The synergistic effect of the hierarchical configuration endows the electrode material with a high specific capacitance of 1037 F g-1at 1 A g-1and excellent cycling stability (∼89% of initial capacitance after 7000 cycles). Moreover, an asymmetric supercapacitor based on the composite and activated carbon achieves a high energy density of 37.7 Wh kg-1 at a power density of 465 W kg-1 in 1.65 V. This work may provide a feasible strategy to design high-performance hybrid electrodes for energy storage devices.

Posttraumatic Stress, Anxiety, and Depression in COVID-19 Survivors.

OBJECTIVES: This study aims to examine the rates of anxiety, depression, and posttraumatic stress disorder (PTSD) after hospital discharge among COVID-19 survivors and to determine the associated risk factors. METHODS: Adult COVID-19 survivors discharged from hospitals between March 2020 and March 2021 were asked to complete a questionnaire at 4 weeks after discharge. The Chinese version of the 22-item Impact of Event Scale - Revised (IES-R) was used to measure symptoms of PTSD. The 9-item Patient Health Questionnaire (PHQ-9) was used to assess symptoms of major depressive disorder. The 7-item Generalised Anxiety Disorder Scale (GAD-7) was used to measure symptoms of generalised anxiety disorder. The rates of anxiety, depression, and PTSD among discharged patients were determined, as were associations between psychosocial factors and outcome measures and predictors for moderate-tosevere symptoms of anxiety, depression, and PTSD. RESULTS: 96 men and 103 women aged 18 to 81 years returned the completed questionnaire. 12.1% to 20.1% of them reported symptoms of PTSD, anxiety, or depression. Higher symptom severity was associated with higher perceived life threat, lower emotional support, lower disease severity upon admission, and longer hospital stay. Women had more PTSD symptoms than men, particularly when knowing someone under quarantine. CONCLUSION: COVID-19 survivors with higher perceived life threat, lower emotional support, lower disease severity upon admission, and longer hospital stay were associated with higher severity of symptoms of PTSD, anxiety, and depression. Timely intervention should provide to at-risk survivors.

Core-shell nanowires of NiCo2O4@α-Co(OH)2 on Ni foam with enhanced performances for supercapacitors.

The composites of NiCo2O4 with unique structures are extensively explored as promising electrodes. In this work, core-shell structured nanowires anchored on nickel foam are synthesized by the hydrothermal synthesis of NiCo2O4 as core and subsequent electrodeposition of α-Co(OH)2 as shell. The core-shell composites exhibit enhanced electrochemical performances ascribing to the synergistic reactions from both materials, showing higher specific capacitance than any single component. By changing the deposition time, the mass loading of α-Co(OH)2 can be easily controlled. The electrochemical performances of the hybrid electrodes are diverse with the mass loading of Co(OH)2. The optimized hybrid electrode with 3 mins electrodeposition exhibits the highest specific capacitance (1298 F g-1 at 1 A g-1) among all electrodes. The redox reaction is a main contributor to the total specific capacitance through electrochemical kinetics analysis. An asymmetric supercapacitor assembled by the optimized material as positive electrode and activated carbon as negative electrode can achieve a relatively high energy density of 39.7 Wh kg-1 at a power density of 387.5 W kg-1 (at 0.5 A g-1) in a voltage of 1.55 V.

Direct Detection Constraints on Dark Photons with the CDEX-10 Experiment at the China Jinping Underground Laboratory.

We report constraints on the dark photon effective kinetic mixing parameter (κ) with data taken from two p-type point-contact germanium detectors of the CDEX-10 experiment at the China Jinping Underground Laboratory. The 90% confidence level upper limits on κ of solar dark photon from 205.4 kg-day exposure are derived, probing new parameter space with masses (m_{V}) from 10 to 300 eV/c^{2} in direct detection experiments. Considering dark photon as the cosmological dark matter, limits at 90% confidence level with m_{V} from 0.1 to 4.0 keV/c^{2} are set from 449.6 kg-day data, with a minimum of κ=1.3×10^{-15} at m_{V}=200 eV/c^{2}.

Patients' Reports of Traumatic Experience and Posttraumatic Stress in Psychiatric Settings.

OBJECTIVE: To determine the prevalence of traumatic experience (TE) among patients in psychiatric settings in Hong Kong and the associations between TE and levels of distress and anxiety and depressive symptoms. METHODS: 129 patients who have received inpatient psychiatric services were recruited. Their lifetime TE was assessed using the Life Event Checklist (LEC), and TE in psychiatric settings using the Psychiatric Experiences Questionnaire (PEQ). Their level of distress symptoms was assessed using the Impact of Event Scale-Revised (IES-R), and the level of anxiety and depressive symptoms using the Hospital Anxiety and Depression Scale (HADS). RESULTS: The prevalence of direct and indirect TE was 84.5%, as was the prevalence of TE in psychiatric settings. Common TE in psychiatric settings included witnessing another patient being taken down (61.2%), being put in restraints of any kind (41.1%), and witnessing another patient being physically assaulted by another patient (36.4%). TE in psychiatric settings associated with high prevalence of severe or extreme distress 1 week after the event included being forced to take medication against their will (52.2%), being threatened with physical violence (52.2%), and experiencing a physical assault (50.0%). Lifetime TE (the total number of LEC items reported) was associated with severity of distress and anxiety and depressive symptoms, whereas TE in psychiatric settings (the total number of PEQ items reported) was associated with severity of distress only. The total number of LEC items reported is the only predictor of levels of distress and anxiety and depressive symptoms. CONCLUSIONS: Lifetime TE and TE in psychiatric settings are common among patients with SMI. Trauma-informed care is suggested for mental health services.

Search for Light Weakly-Interacting-Massive-Particle Dark Matter by Annual Modulation Analysis with a Point-Contact Germanium Detector at the China Jinping Underground Laboratory.

We present results on light weakly interacting massive particle (WIMP) searches with annual modulation (AM) analysis on data from a 1-kg mass p-type point-contact germanium detector of the CDEX-1B experiment at the China Jinping Underground Laboratory. Datasets with a total live time of 3.2 yr within a 4.2-yr span are analyzed with analysis threshold of 250 eVee. Limits on WIMP-nucleus (χ-N) spin-independent cross sections as function of WIMP mass (m_{χ}) at 90% confidence level (C.L.) are derived using the dark matter halo model. Within the context of the standard halo model, the 90% C.L. allowed regions implied by the DAMA/LIBRA and CoGeNT AM-based analysis are excluded at >99.99% and 98% C.L., respectively. These results correspond to the best sensitivity at m_{χ}<6 GeV/c^{2} among WIMP AM measurements to date.

Constraints on Spin-Independent Nucleus Scattering with sub-GeV Weakly Interacting Massive Particle Dark Matter from the CDEX-1B Experiment at the China Jinping Underground Laboratory.

We report results on the searches of weakly interacting massive particles (WIMPs) with sub-GeV masses (m_{χ}) via WIMP-nucleus spin-independent scattering with Migdal effect incorporated. Analysis on time-integrated (TI) and annual modulation (AM) effects on CDEX-1B data are performed, with 737.1 kg day exposure and 160 eVee threshold for TI analysis, and 1107.5 kg day exposure and 250 eVee threshold for AM analysis. The sensitive windows in m_{χ} are expanded by an order of magnitude to lower DM masses with Migdal effect incorporated. New limits on σ_{χN}^{SI} at 90% confidence level are derived as 2×10^{-32}∼7×10^{-35} cm^{2} for TI analysis at m_{χ}∼50-180 MeV/c^{2}, and 3×10^{-32}∼9×10^{-38} cm^{2} for AM analysis at m_{χ}∼75 MeV/c^{2}-3.0 GeV/c^{2}.

Synthesis of single-phase CuCo2-xNixS4 for high-performance supercapacitors.

Developing safe, efficient and environment-friendly energy storage systems continues to inspire researchers to synthesize new electrode materials. Doping or substituting host material by some guest elements has been regarded as an effective way to improve the performance of supercapacitors. In this work, single-phase CuCo2-xNixS4 materials were synthesized by a facile two-step hydrothermal method, where Co in CuCo2S4 was substituted by Ni. Cobalt could be easily substituted with Ni in a rational range to keep its constant phase. But, a high content of Ni resulted in a multi-phase composite. Among a series of CuCo2-xNixS4 materials with different Ni/Co mole ratios, CuCo1.25Ni0.75S4 material presented a significantly high specific capacitance (647 F g-1 or 272 C g-1 at 1 A g-1) and the best cycling stability (∼98% specific capacitance retention after 10,000 charge-discharge cycles), which was mainly due to the modified composition, specific single phase, higher electroconductivity, more electroactive sites and the synergistic effect between Ni and Co. Moreover, the assembled asymmetric capacitor using CuCo1.25Ni0.75S4 as a positive electrode and activated carbon as a negative electrode delivered a high energy density of 31.8 Wh kg-1 at the power density of 412.5 W kg-1. These results demonstrated that ternary metal sulfides of CuCo2-xNixS4 are promising electrode materials for high-performance supercapacitors.

Limits on Light Weakly Interacting Massive Particles from the First 102.8 kg×day Data of the CDEX-10 Experiment.

We report the first results of a light weakly interacting massive particles (WIMPs) search from the CDEX-10 experiment with a 10 kg germanium detector array immersed in liquid nitrogen at the China Jinping Underground Laboratory with a physics data size of 102.8 kg day. At an analysis threshold of 160 eVee, improved limits of 8×10^{-42} and 3×10^{-36} cm^{2} at a 90% confidence level on spin-independent and spin-dependent WIMP-nucleon cross sections, respectively, at a WIMP mass (m_{χ}) of 5 GeV/c^{2} are achieved. The lower reach of m_{χ} is extended to 2 GeV/c^{2}.

CoO microspheres and metallic Co evolved from hexagonal α-Co(OH)2 plates in a hydrothermal process for lithium storage and magnetic applications.

CoO microspheres and metallic Co could be successfully synthesized by simply reacting cobalt acetate with a mixture solvent of ethylene glycol and deionized water in a hydrothermal process for different times. As the reaction proceeded, α-Co(OH)2, CoO and metallic Co were produced. To understand the phase evolution processes from α-Co(OH)2 to CoO and then metallic Co, a range of time-dependent experiments were carried out, and the intermediate products obtained at different reaction times were investigated in detail. The investigation revealed that CoO microspheres were actually evolved from α-Co(OH)2 as a precursor. Just elongating the reaction time, CoO microspheres could be further reduced to metallic Co. With a pure ethylene glycol medium for the same reaction, only α-Co(OH)2 could be generated, indicating an important role of water. When the obtained CoO microspheres were used as anode materials for lithium-ion batteries, they delivered a specific capacity of 803 mA h g-1 at 0.1 A g-1 with a retention of 453 mA h g-1 after 70 cycles. Meanwhile, the magnetic properties of the obtained CoO microspheres and metallic Co were investigated, with the CoO microspheres showing an antiferromagnetic behavior and the metallic Co exhibiting ferromagnetic characteristics. This study suggested a novel method for synthesizing CoO with a uniform microsphere morphology and bulk metallic Co easily.

Template-free synthesis of hierarchical hollow NiSx microspheres for supercapacitor.

Hierarchical nickel sulfide (NiSx) hollow microspheres can be successfully synthesized with a template-free method using α-Ni(OH)2 microspheres as a precursor by calcination and sulfidation. The intermediate Ni hollow spheres, formed at different calcination temperatures (300°C and 400°C) under H2/N2 atmosphere, can be easily transformed into NiSx with similar morphology and mixed phases of Ni3S2 and NiS during the followed sulfidation process. The formation processes for the hollow structure of NiSx are also discussed in this work. Particularly, the NiSx prepared from Ni intermediate spheres at 300°C show a high specific capacity of 153.6mAhg-1 at 0.5Ag-1 at high mass loading due to its small crystal size, hierarchically porous structure and high electrical conductivity. A hybrid capacitor was assembled by using it as positive electrode and activated carbon as negative electrode to examine their practical applications in a full-cell configuration. The hybrid capacitor exhibited excellent comprehensive performances in 1.6V. The hybrid capacitor also showed good cycling stability, with 81.25% of the initial specific capacitance after 1000 cycles at 2Ag-1. Above results indicate the great potential of the NiSx hollow spheres as a promising electrode material for supercapacitor applications.

Hybrid nanomaterial of α-Co(OH)2 nanosheets and few-layer graphene as an enhanced electrode material for supercapacitors.

Supercapacitor with metal hydroxide nanosheets as electrode can have high capacitance. However, the cycling stability and high rate capacity is low due to the low electrical conductivity. Here, the exfoliated α-Co(OH)2 nanosheets with high capacitance has been assembled on few-layer graphene with high electric conductivity by a facile yet effective and scalable solution method. Exfoliated hydrotalcite-like α-Co(OH)2 nanosheets and few-layer graphene suspensions were prepared by a simple ultrasonication in formamide and N-methyl-2-pyrrolidone, respectively. Subsequently, a hybrid was made by self-assembly of α-Co(OH)2 and few-layer graphene when the two dispersions were mixed at room temperature. The hybrid material provided a high specific capacitance of 567.1F/g at 1A/g, while a better rate capability and better stability were achieved compared to that mad of pristine and single exfoliated α-Co(OH)2. When the hybrid nanocomposite was used as a positive electrode and activated carbon was applied as negative electrode to assembly an asymmetric capacitor, an energy density of 21.2Wh/kg at a power density of 0.41kW/kg within a potential of 1.65V was delivered. The high electrochemical performance and facile solution-based synthesis method suggested that the hybrid of exfoliated α-Co(OH)2/few-layer graphene could be a potential electrode material for electrochemical capacitor.