Realizing multiferroics in α-Ga2S3via hole doping: a first-principles study.

Using first-principles calculations, we report the realization of multiferroics in an intrinsic ferroelectric α-Ga2S3 monolayer. Our results show that the presence of intrinsic gallium vacancies, which is the origin of native p-type conductivity, can simultaneously introduce a ferromagnetic ground state and a spontaneous out-of-plane polarization. However, the high switching barrier and thermodynamic irreversibility of the ferroelectric reversal path disable the maintenance of ferroelectricity, suggesting that the defect-free form should be a prerequisite for Ga2S3 to be multiferroic. Through applying strain, the behavior of spontaneous polarization of the pristine α-Ga2S3 monolayer can be effectively regulated, but the non-magnetic ground state does not change. Strikingly, via an appropriate concentration of hole doping, stable ferromagnetism with a high Curie temperature and robust ferroelectricity can be concurrently introduced in the α-Ga2S3 monolayer. Our work provides a feasible method for designing 2D multiferroics with great potential in future device applications.

Clinical characteristics and prognosis of pediatric Listeria monocytogenes meningitis based on 10-year data from a large children's hospital in China.

This study aims to summarize the clinical characteristics and prognosis of Listeria monocytogenes (LM) meningitis in children in Chongqing, China. A retrospective analysis of the clinical data and follow-up results of 20 LM meningitis patients admitted to the Children's Hospital of Chongqing Medical University (CHCMU) from January 2012 to December 2022 was performed. The LM meningitis incidence rate was between 0 and 14.3 per 100,000 persons. The median age at onset was 8.98 months. There were five neonate cases, which all had perinatal abnormalities. Seven non-neonatal cases (7/15, 46.7%) had a documented history of contaminated food intake. One case had primary immunodeficiency. The most common symptoms were fever (20/20), altered consciousness (19/20), and vomiting (15/20). Seven cases had seizures, eight cases had cranial nerve involvement, eight cases had positive Babinski sign, and 10 cases had positive meningeal signs. The most common complications were hyponatremia (6/20), hypokalemia (6/20), respiratory failure (5/20), subdural effusion (3/20), and hydrocephalus (2/20). Treatment primarily involved monotherapy or combination therapy with meropenem (15/20) and ampicillin (10/20). Fifteen cases were treated with monotherapy or combination therapy using vancomycin. Twelve cases were successfully followed up from 10 months to 9 years and 6 months, and all had favorable long-term outcomes. LM meningitis incidence in children is low and with nonspecific clinical manifestations. Strengthening food hygiene and safety education, and avoiding infections during pregnancy are important to prevent LM infection in neonates and high-risk individuals. Meropenem and ampicillin are the preferred treatments. Early diagnosis and treatment can improve prognosis.IMPORTANCEThe incidence of LM meningitis is extremely low, and there is currently no standardized treatment. We conducted a retrospective analysis of ten years of data from CHCMU regarding diagnosed LM meningitis cases, aiming to provide clinical evidence for the diagnosis and treatment.

Precise Engineering of the Electrocatalytic Activity of FeN4-Embedded Graphene on Oxygen Electrode Reactions by Attaching Electrides.

Using first-principles calculations combined with a constant-potential implicit solvent model, we comprehensively studied the activity of oxygen electrode reactions catalyzed by electride-supported FeN4-embedded graphene (FeN4Cx). The physical quantities in FeN4Cx/electrides, i.e., work function of electrides, interlayer spacing, stability of heterostructures, charge transferred to Fe, d-band center of Fe, and adsorption free energy of O, are highly intercorrelated, resulting in activity being fully expressed by the nature of the electrides themselves, thereby achieving a precise modulation in activity by selecting different electrides. Strikingly, the FeN4PDCx/Ca2N and FeN4PDCx/Y2C systems maintain a high oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) activity with the overpotential less than 0.46 and 0.62 V in a wide pH range. This work provides an effective strategy for the rational design of efficient bifunctional catalysts as well as a model system with a simple activity-descriptor, helping to realize significant advances in energy devices.

TM2 -B2 Quadruple Active Sites Supported on a Defective C3 N Monolayer as Catalyst for the Electrochemical CO2 Reduction: A Theoretical Perspective.

Developing high-performance electrocatalysts for the CO2 reduction reaction (CO2 RR) holds great potential to mitigate the depletion of fossil feedstocks and abate the emission of CO2 . In this contribution, using density functional theory calculations, we systematically investigated the CO2 RR performance catalyzed by TM2 -B2 (TM=Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu) supported on a defective C3 N monolayer (V-C3 N). Through the screening in terms of stability of catalyst, activity towards CO2 adsorption, and selectivity against hydrogen evolution reaction, Mn2 -, Fe2 -, Co2 -, and Ni2 -B2 @V-C3 N were demonstrated to be a highly promising CO2 RR electrocatalyst. Due to quadruple active sites, these candidates can adsorb two or three CO2 molecules. Strikingly, different products, distributing from C1 to C2+ , can be generated. The high activity originates from the synergistic effect of TM and B atoms, in which they serve as adsorption sites for the C- and O-species, respectively. The high selectivity towards C2+ products at the Fe2 -, and Ni2 -B2 sites stems from moderate C adsorption strength but relatively weak O adsorption strength, in which a universal descriptor, that is, 0.6 ΔEC -0.4 ΔEO =-1.77 eV (ΔEC /ΔEO is the adsorption energy of C/O), was proposed. This work would offer a novel perspective for the design of high active electrocatalysts towards CO2 RR and for the synthesis of C2+ compounds.