The photoelectron-imaging spectroscopic study and chemical bonding analysis of VO2−, NbO2− and TaO2−

The transition-metal di-oxides, namely VO₂⁻, NbO₂⁻ and TaO₂⁻ have been studied using photoelectron velocity map imaging (PE-VMI) in combination with theoretical calculations. The adiabatic electron affinities of VO₂⁻, NbO₂⁻ and TaO₂⁻ are confirmed to be 2.029(8), 1.901(10) and 2.415(8) eV, respectively. By combining Franck–Condon (FC) simulation with theoretical calculations, the vibrational feature related to Nb–O and Ta–O stretching modes for the ground state has been unveiled. The photoelectron angular distribution (PAD) for VO₂⁻, NbO₂⁻ and TaO₂⁻ is correlated to the photo-detachment of the highest occupied molecular orbitals (HOMOs), which primarily gets involved in s- and d-orbitals of the V, Nb and Ta atoms. A variety of theoretical calculations have been used to analyze the chemical bonding features of VO₂^−1/0, NbO₂^−1/0 and TaO₂^−1/0, which show that the strong M–O (M = V, Nb and Ta) bond is mainly characterized as ionicity.

The transition-metal di-oxides, namely VO₂⁻, NbO₂⁻ and TaO₂⁻ have been studied using photoelectron velocity map imaging (PE-VMI) in combination with theoretical calculations.     

LiFePO4-coated LiNi0.6Co0.2Mn0.2O2 for lithium-ion batteries with enhanced cycling performance at elevated temperatures and high voltages

LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) is a highly promising cathode material owing to its high capacity; however, it is characterized by inferior cycling performance and safety problems. We report a novel strategy to improve electrochemical characteristics and safety issues of NCM622 by coating it with LiFePO₄ (LFP). Although having a lower capacity, LFP is a safe and long-cycle cathode material; it is more chemically and thermally stable than NCM622 when exposed to common electrolytes. The LFP-coated NCM622 (NCM@LFP) showed similar rate performance and cycling performance at room temperature compared with the pristine NCM622 under the same conditions. However, significant differences between the NCM622 and NCM@LFP began to emerge at high temperatures. During cycling at 1C for 100 cycles at 55 °C, NCM@LFP showed much improved specific discharge capacity retentions of 92.4%, 90.9%, and 88.2% in the voltage ranges of 3–4.3 V, 3–4.4 V and 3–4.5 V, respectively. The NCM622 suffered significant discharge specific capacity decay under the same condition. In addition, as demonstrated by the delayed exothermic peak in the differential scanning calorimetry (DSC) test, NCM@LFP exhibited excellent thermal stability compared with NCM622, which is critical to battery safety.

LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) is a highly promising cathode material owing to its high capacity; however, it is characterized by inferior cycling performance and safety problems.     

Certification in Medical Physics Imaging,The Workforce and Training Models

The pathway to becoming a qualified medical physicist (QMP) in the imaging physics disciplines includes several certification organizations. Imaging QMPs play an essential role in the safe practice of the diagnostic disciplines, and their qualifications are necessary for compliance with federal bodies and professional accreditation organizations. The future demand for imaging QMPs is largely unknown, but professional organizations that represent these groups agree that efforts should be made to increase the number of matriculating trainees. The number of imaging residency programs that provide the necessary professional experience to enter the certification pathway has increased substantially in recent years. Most of these programs follow a traditional academic hospital-based training model, but guidance on program construction from the accrediting body permits flexibility. Existing training models for medical physics imaging also include consortiums of affiliate partners and private consulting service groups. In this article, the authors briefly review the certification pathways for imaging QMPs, workforce estimates, and training models.     

Hypermetabolism associated with worse prognosis of amyotrophic lateral sclerosis

Journal of Neurology - Exploration of hypermetabolism in amyotrophic lateral sclerosis (ALS) with different ethnicities is needed to understand its metabolic implications for clinical management....     

Main lymphocyte subpopulations in cerebrospinal fluid and peripheral blood in HIV-1 subtypes C and B

Journal of NeuroVirology - HIV-1 subtype C (HIV-1C) shows reduced Tat protein chemoattractant activity compared with HIV-1B. The impact of HIV-1C Tat on the chemotaxis of the main lymphocyte...     

A review of ischemic stroke in COVID-19: currently known pathophysiological mechanisms

Neurological Sciences - Coronavirus disease 2019 (COVID-19), the third type of coronavirus pneumonia after severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), is...     

慢性活动性肝炎的胆囊超声切面显像

一、方法我院从1984年9月至1985年8月选择了未用抗菌素的慢活肝住院患者67例(均经流行病学,临床及实验室资料确定诊断)的胆囊壁增厚的发生率及其它异常作了分析.67例中,男54例,女13例:平均年龄39岁,最小19岁,最大67岁;平均病程6年,最短7个月,最长29年,67例慢活肝中乙