Searching for Two-Neutrino and Neutrinoless Double Beta Decay of

^{134}Xe is a candidate isotope for neutrinoless double beta decay (0νßß) search. In addition, the two-neutrino case (2νßß) allowed by the standard model of particle physics has not yet been observed. With the 656-kg natural xenon in the fiducial volume of the PandaX-4T detector, which contains 10.4% of ^{134}Xe, and its initial 94.9-day exposure, we have established the most stringent constraints on 2νßß and 0νßß of ^{134}Xe half-lives, with limits of 2.8×10^{22} yr and 3.0×10^{23} yr at 90% confidence level, respectively. The 2νßß (0νßß) limit surpasses the previously reported best result by a factor of 32 (2.7), highlighting the potential of large monolithic natural xenon detectors for double beta decay searches.

Search for Light Dark Matter with Ionization Signals in the PandaX-4T Experiment.

We report the search results of light dark matter through its interactions with shell electrons and nuclei, using the commissioning data from the PandaX-4T liquid xenon detector. Low energy events are selected to have an ionization-only signal between 60 to 200 photoelectrons, corresponding to a mean nuclear recoil energy from 0.77 to 2.54 keV and electronic recoil energy from 0.07 to 0.23 keV. With an effective exposure of 0.55 tonne·year, we set the most stringent limits within a mass range from 40 MeV/c^{2} to 10 GeV/c^{2} for pointlike dark matter-electron interaction, 100 MeV/c^{2} to 10 GeV/c^{2} for dark matter-electron interaction via a light mediator, and 3.2 to 4 GeV/c^{2} for dark matter-nucleon spin-independent interaction. For DM interaction with electrons, our limits are closing in on the parameter space predicted by the freeze-in and freeze-out mechanisms in the early Universe.

Search for Light Dark Matter from the Atmosphere in PandaX-4T.

We report a search for light dark matter produced through the cascading decay of η mesons, which are created as a result of inelastic collisions between cosmic rays and Earth's atmosphere. We introduce a new and general framework, publicly accessible, designed to address boosted dark matter specifically, with which a full and dedicated simulation including both elastic and quasielastic processes of Earth attenuation effect on the dark matter particles arriving at the detector is performed. In the PandaX-4T commissioning data of 0.63 tonne·year exposure, no significant excess over background is observed. The first constraints on the interaction between light dark matter generated in the atmosphere and nucleus through a light scalar mediator are obtained. The lowest excluded cross section is set at 5.9×10^{-37} cm^{2} for a dark matter mass of 0.1 MeV/c^{2} and mediator mass of 300 MeV/c^{2}. The lowest upper limit of η to the dark matter decay branching ratio is 1.6×10^{-7}.

Search for Solar

A search for interactions from solar ^{8}B neutrinos elastically scattering off xenon nuclei using PandaX-4T commissioning data is reported. The energy threshold of this search is further lowered compared with the previous search for dark matter, with various techniques utilized to suppress the background that emerges from data with the lowered threshold. A blind analysis is performed on the data with an effective exposure of 0.48 tonne year, and no significant excess of events is observed. Among the results obtained using the neutrino-nucleus coherent scattering, our results give the best constraint on the solar ^{8}B neutrino flux. We further provide a more stringent limit on the cross section between dark matter and nucleon in the mass range from 3 to 9 GeV/c^{2}.

Search for Dark-Matter-Nucleon Interactions with a Dark Mediator in PandaX-4T.

We report results of a search for dark-matter-nucleon interactions via a dark mediator using optimized low-energy data from the PandaX-4T liquid xenon experiment. With the ionization-signal-only data and utilizing the Migdal effect, we set the most stringent limits on the cross section for dark matter masses ranging from 30 MeV/c^{2} to 2 GeV/c^{2}. Under the assumption that the dark mediator is a dark photon that decays into scalar dark matter pairs in the early Universe, we rule out significant parameter space of such thermal relic dark-matter model.

Powerful Orbital Hybridization of Copper-Silver Bimetallic Nanosheets for Electrocatalytic Nitrogen Reduction to Ammonia.

Electrochemical nitrogen reduction (eNRR) is a promising strategy to replace the energy- and capital-intensive Haber-Bosch process. Unfortunately, the low selectivity of the eNRR process impedes the industrial application of this approach. In this work, a highly efficient and stable NRR electrocatalyst is obtained via coreduction of Cu and Ag precursors using the holly leaves as reducing agents. The as-obtained Cu3Ag bimetallic nanosheets exhibit excellent NRR performance with an NH3 production rate of 31.3 µg h-1 mg-1cat. and a Faradaic efficiency of 31.3% at -0.2 V vs RHE. According to density functional theory (DFT) calculation, the outstanding performance of Cu3Ag bimetallic nanosheets could be caused by the fact that Ag optimizes the 3d orbital occupation of Cu and synergistically enhances the charge transfer during the NRR process, resulting in a suitable adsorption strength of the intermediates.

Coordinated Patient Care via Mobile Phone-Based Telemedicine in Secondary Stroke Prevention: A Propensity Score-Matched Cohort Study.

BACKGROUND: To prevent recurrent stroke, patients need to follow evidence-based practices following discharge; however, adherence to these practices is suboptimal. PURPOSE: To evaluate whether a smartphone mobile application can improve medication adherence and stroke awareness in secondary stroke prevention. METHODS: A retrospective study design was used. Patients with ischemic stroke registered in a database between August 2018 and January 2019 were enrolled. Propensity score matching was used to match patients managed with the mobile application compared with regular practice in a 1:2 ratio. RESULTS: Sixty-five patients were paired with 123 controls. Three-month medication adherence was 93.8% in the application group versus 82.9% in the control group ( P = .036). Patients in the application group were more likely to know stroke warning signs ( P = .003) and when to call an ambulance for stroke symptoms (87.7% vs 72.4%, P = .016). CONCLUSIONS: Using a mobile application may increase medication adherence and stroke awareness in secondary stroke prevention.

Search for Cosmic-Ray Boosted Sub-GeV Dark Matter at the PandaX-II Experiment.

We report a novel search for the cosmic-ray boosted dark matter using the 100 tonne·day full dataset of the PandaX-II detector located at the China Jinping Underground Laboratory. With the extra energy gained from the cosmic rays, sub-GeV dark matter particles can produce visible recoil signals in the detector. The diurnal modulations in rate and energy spectrum are utilized to further enhance the signal sensitivity. Our result excludes the dark matter-nucleon elastic scattering cross section between 10^{-31} and 10^{-28} cm^{2} for dark matter masses from 0.1 MeV/c^{2} to 0.1 GeV/c^{2}, with a large parameter space previously unexplored by experimental collaborations.

First Search for the Absorption of Fermionic Dark Matter with the PandaX-4T Experiment.

Compared with the signature of dark matter elastic scattering off nuclei, the absorption of fermionic dark matter by nuclei opens up a new searching channel for light dark matter with a characteristic monoenergetic signal. In this Letter, we explore the 95.0-day data from the PandaX-4T commissioning run and report the first dedicated searching results of the fermionic dark matter absorption signal through a neutral current process. No significant signal was found, and the lowest limit on the dark matter-nucleon interaction cross section is set to be 1.5×10^{-50} cm^{2} for a fermionic dark matter mass of 40 MeV/c^{2} with 90% confidence level.

Search for Light Fermionic Dark Matter Absorption on Electrons in PandaX-4T.

We report a search on sub-MeV fermionic dark matter absorbed by electrons with an outgoing active neutrino using the 0.63 tonne year exposure collected by the PandaX-4T liquid xenon experiment. No significant signals are observed over the expected background. The data are interpreted into limits to the effective couplings between such dark matter and the electron. For axial-vector or vector interactions, our sensitivity is competitive in comparison to existing astrophysical bounds on the decay of such a dark matter candidate into photon final states. In particular, we present the first direct detection limits for a vector (axial-vector) interaction which are the strongest in the mass range from 35 to 55 (25 to 45) keV/c^{2} in comparison to other astrophysical and cosmological constraints.

Increased Oxygen Vacancies in CeO2 for Improved Electrocatalytic Nitrogen Reduction Performance.

Electrochemical nitrogen fixation is a sustainable and economical strategy to produce ammonia. However, fabricating efficient electrocatalysts for nitrogen fixation is still challenging. Theoretical predictions prove that the oxygen vacancy is able to modulate the electronic state of CeO2 and enhance its electrical conductivity, thus promoting the electrochemical nitrogen reduction reaction (NRR) process. Herein, CeO2 with high oxygen vacancy concentration was prepared via a two-step pyrolysis strategy of Ce metal-organic frameworks (MOFs, denoted H-CeO2). Compared to CeO2 with low oxygen vacancy concentration synthesized via one-step pyrolysis of Ce-MOFs (denoted L-CeO2), H-CeO2 exhibits a large NH3 yield rate (25.64 µg h-1 mgcat-1 at -0.5 V vs reversible hydrogen electrode, RHE) and high faradaic efficiency (FE, 6.3% at -0.4 V vs RHE).

Development and psychometric testing of burn inpatient nursing dependency assessment scale.

AIMS: The aim was to develop and psychometrically test the burn inpatient nursing dependency assessment scale (BINDAS). DESIGN: This was a scale development study. METHODS: This study was conducted in four phases from November 2019 to November 2021. Items were generated and the initial scale was constructed in phase 1. The preliminary evaluation of items was conducted through expert reviews and a pilot study in phase 2. The scale, including item quality, reliability and validity, was validated with 420 individuals in phase 3. The translation of the scale from Chinese to English was performed in phase 4. RESULTS: Content validity was satisfactory. Thirteen items were retained after item analysis, and three factors accounting for 73% of the total item variance were extracted through exploratory and confirmatory factor analyses. Predictive validity with nursing time spent with patients during 24 h was also estimated, with r = .66 (p < .01). Receiver operating characteristic analysis was conducted, and an area under the curve of the scale of 0.94 was obtained. Concurrent validity with Barthel index was estimated, with r = -.71 (p < .01). Cronbach's alpha coefficient for scale was .93, and the correlation between raters for total scores was .95. CONCLUSION: Burn inpatient nursing dependency assessment scale is a psychometrically valid and reliable measurement instrument as well as objective other-rating scale with 12 items for scoring on a four-point scale (0, 1, 2 or 3) and 1 item for scoring on a two-point scale (0 or 2). BINDAS with 13 items was developed in this study. Nurses can give each patient a total score of 0-38. A high score indicates high nursing dependency. The 13-item scale consists of three factors: basic care need, physiological index, and psychology and adaptation. IMPACT: This scale demonstrated satisfactory psychometric properties and can be used to evaluate patient dependency on nurses in burn units and optimize an individual's care plan to achieve efficient staff allocation.

The Antioxidant and Hypolipidemic Effects of Mesona Chinensis Benth Extracts.

In this study, the antioxidant and hypolipidemic effects of Mesona Chinensis Benth (MCB) extracts were evaluated. Seven fractions (F0, F10, F20, F30, F40, F50 and MTF) were obtained from the MCB ethanol extracts. Compared to the commercial antioxidants (vitamin C), MTF and F30 exhibited higher antioxidant activities in the antiradical activity test and the FRAP assay. The half-inhibition concentration (IC50) for MTF and F30 were 5.323 µg/mL and 5.278 µg/mL, respectively. MTF at 200 µg/mL significantly decreased the accumulation of TG in oleic acid (OA)-induced HepG2 cells and reversed the inhibitory effect of Compound C on AMPK (MTF and F30 significantly increased the glucose utilization of insulin-induced HepG2 cells). In addition, the components of MTF were identified by HPLC-MS, which were caffeic acid, quercetin 3-O-galactoside, isoquercetin, astragalin, rosmarinic acid, aromadendrin-3-O-rutinoside, rosmarinic acid-3-O-glucoside and kaempferol-7-O-glucoside. Through statistical correlations by Simca P software, it was found that the main antioxidant and hypolipidemic components of MCB might be caffeic acid, kaempferol-7-O-glucoside, rosmarinic acid-3-O-glucoside and aromadendrin-3-O-rutinoside, which may play important roles in the AMPK pathway. MTF and F30 in MCB could be potential health products for the treatment of hyperlipidemia.

Search for Light Dark Matter-Electron Scattering in the PandaX-II Experiment.

We report constraints on light dark matter through its interactions with shell electrons in the PandaX-II liquid xenon detector with a total 46.9 tonnes/day exposure. To effectively search for these very low energy electron recoils, ionization-only signals are selected from the data. 1821 candidates are identified within an ionization signal range between 50 and 75 photoelectrons, corresponding to a mean electronic recoil energy from 0.08 to 0.15 keV. The 90% C.L. exclusion limit on the scattering cross section between the dark matter and electron is calculated with systematic uncertainties properly taken into account. Under the assumption of point interaction, we provide the world's most stringent limit within the dark matter mass range from 15 to 30 MeV/c^{2}, with the corresponding cross section from 2.5×10^{-37} to 3.1×10^{-38} cm^{2}.

Dark Matter Search Results from the PandaX-4T Commissioning Run.

We report the first dark matter search results using the commissioning data from PandaX-4T. Using a time projection chamber with 3.7 tonne of liquid xenon target and an exposure of 0.63 tonne·year, 1058 candidate events are identified within an approximate nuclear recoil energy window between 5 and 100 keV. No significant excess over background is observed. Our data set a stringent limit to the dark matter-nucleon spin-independent interactions, with a lowest excluded cross section (90% C.L.) of 3.8×10^{-47} cm^{2} at a dark matter mass of 40 GeV/c^{2}.

Phylogenetically divergent bacteria consortium from neutral activated sludge showed heightened potential on bioleaching spent lithium-ion batteries.

Recycling of spent lithium-ion batteries (LIBs) has become a global issue because of the potential environment risks raised by spent LIBs as well as high valuable metal content remaining in them. Although bioleaching is an environmentally friendly method to recover metals from spent LIBs, the commonly utilized bioleaching bacterial consortia or strains enriched/isolated from acidic environments cannot be applied at large scales owing to their long leaching cycle and poor tolerance to organic compounds. Here, two bioleaching consortia were enriched in 60 days from neutral activated sludge and were identified phylogenetically divergent from the documented bioleaching bacteria. The results showed that the novel consortia shortened the leaching cycle almost by half when compared to the previous reported consortia or strains, of which one consortium dominated by Acidithiobacillus ferrooxidans displayed high bioleaching efficiency on LiMn2O4, as 69.46% lithium (Li) and 67.60% manganese (Mn) were leached out in seven days. This consortium was further domesticated using cathodic materials for 100 days and proved consisted of three mixotrophs and two chemoautotrophs, three of which were novel species from the genera Sulfobacillus and Leptospirillum. More genes coding for proteins that utilize organic compounds were annotated in the metagenomic assembled genomes (MAGs) than previously reported. A mutualistic relationship between mixotrophs and chemoautotrophs was suggested to help the consortium surviving under either organic- rich or shortage environments. The results discovered that novel bioleaching bacteria with shorter leaching cycle and higher tolerance to organics could be enriched from non-acidic environments, which showed high potential for the metal recovering from spent LIBs or other organic-rich environments.

Preparation of SnS2/MWCNTs chemically modified electrode and its electrochemical detection of H2O2.

Considering the importance of hydrogen peroxide (H2O2) rapid detection, a SnS2/MWCNTs composite was prepared by loading tin disulfide (SnS2) nanoparticles on a three-dimensional conductive network composed of multi-walled carbon nanotubes (MWCNTs). The obtained SnS2/MWCNTs composite was used as the modified material to prepare a chemically modified electrode (CME), which was used for the rapid detection of H2O2. The morphology and structure of the obtained samples were characterized and analyzed by scanning electron microscopy, X-ray diffraction, and energy-dispersive spectroscopy. The electrochemical performance of the modified electrode was researched by cyclic voltammetry, amperometric i-t curves, and AC impedance techniques. The results show that SnS2 nanoparticles with a size of about 33 nm are evenly dispersed on the surface of MWCNTs. The obtained SnS2/MWCNTs-CME has a strong current response to H2O2: it has a good linear relationship during the range of 0.248 ~ 16.423 mmol L-1, and its linear regression equation is Ipa (mA) = (-0.94 ± 0.05) × 10-2 + (- 0.43 ± 0.06) × 10-2c (mmol L-1) (R2 = 0.997) with a sensitivity of 87.84 µA mmol-1 L cm-2. The corresponding detection limit is 1.04 µmol L-1 (S/N = 3). At the same time, the SnS2/MWCNTs-CME has good selectivity, reproducibility, and stability. Graphical abstract Uniformly distributed SnS2/CNTs composite is used to prepare a chemically modified electrode for H2O2 detection. The prepared electrode has a strong electrochemical response to H2O2 due to the excellent conductivity and support of CNTs. And the SnS2/CNTs electrode shows high sensitivity and selectivity for the electrochemical detection of H2O2.

Microbial characterization of heavy metal resistant bacterial strains isolated from an electroplating wastewater treatment plant.

Heavy metal pollution is one of the most widespread and complex environmental issues globally, posing a great threat to the ecosystem as well as human health. Bioremediation through heavy metal-resistant bacteria (HMRB) is currently the most promising technology to address this issue. To obtain HMRB to remediate heavy metal pollution potentially, 15 culturable HMRB strains were isolated from the sludge samples of an electroplating wastewater treatment plant (EWWTP), which belonged to the Bacillus, Shewanella, Lysinibacillus, and Acinetobacter genera. Their maximum tolerance concentrations to Cu2+, Ni2+, Mn2+, Co2+, and Cr2O72- were 40 mM, 10 mM, 200 mM, 40 mM, and 10 mM, respectively, and strain Mn1-4 showed much higher Mn2+ tolerance and removal effectiveness (3.355 g/L) than previously published reports. Moreover, multiple heavy metal-resistant genotypes and phenotypes were identified among these strains, of which strain Co1-1 carried the most of resistant gene sequences (10) and exhibited resistance to 7 categories of heavy metals, and the co-occurrence of heavy metal and antibiotic resistance were clearly observed in strain Ni1-3. In addition, flanked insert sequence (IS) elements on the heavy metal resistant genes (HMRGs) suggested that horizontal gene transfer (HGT) events may have resulted in multiple heavy metal resistance phenotypes and genotypes in these strains, and IS982 family transposase was presumed to result in the high Ni2+ tolerance in strain Ni1-3. This study expands our understanding of bacterial heavy metal resistance and provides promising candidates for heavy metal bioremediation.

A comprehensive review of anaerobic digestion of organic solid wastes in relation to microbial community and enhancement process.

Organic solid wastes (OSWs) should be regarded as valuable resources rather than dead-end landfill waste that causes public health and odor concerns. Anaerobic digestion (AD) is an ideal approach for managing organic solid waste issues and involves using a group of anaerobic microorganisms to transform OSWs into useful products. In this review, over 100 publications related to AD of OSWs have been compiled, discussed, and analyzed. A comprehensive analysis of the environmental and safety impacts of AD, its key environmental factors, co-digestion, and pretreatment, as well as the AD of OSWs by various anaerobic microbes uncovered by high throughput sequencing-based approaches, is presented. The purpose of this review is to provide an outline of the current knowledge of AD processes from a multi-angle perspective. A comprehensive understanding of AD of OSWs and genome-enabled biology development could be helpful for providing up-to-date knowledge of AD, developing it, overcoming its drawbacks and, ultimately, improving global waste control for more efficient environmental management. © 2018 Society of Chemical Industry.

[Selective control of hindlimb movements based on intraspinal functional electronic stimulation].

Functional electronic stimulation (FES) may provide a means to restore motor function in patients with spinal cord injuries. The goal of this study is to determine the regions in the spinal cord controlling different hindlimb movements in the rats. Normalization was used for the regions dominating the corresponding movements. It has been verified that FES can be used in motor function recovery of the hindlimb. The spinal cord was stimulated by FES with a three-dimensional scan mode in experiments. The results show that stimulation through the electrodes implanted in the ventral locations of the lumbosacral enlargement can produce coordinated single- and multi-joint hindlimb movements. A variety of different hindlimb movements can be induced with the appropriate stimulation sites, and movement vectors of the hindlimb cover the full range of movement directions in the sagittal plane of the hindlimb. This article drew a map about spinal cord motor function of the rat. The regions in the spinal cord which control corresponding movements are normalized. The data in the study provide guidance about the location of electrode tips in the follow-up experiments.