Conversation from antiferromagnetic MnBr2 to ferromagnetic Mn3Br8 monolayer with large MAE

A pressing need in low energy spintronics is two-dimensional (2D) ferromagnets with Curie temperature above the liquid-nitrogen temperature (77 K), and sizeable magnetic anisotropy. We studied Mn3Br8 monolayer which is obtained via inducing Mn vacancy at 1/4 population in MnBr2 monolayer. Such defective configuration is designed to change the coordination structure of the Mn-d5 and achieve ferromagnetism with sizeable magnetic anisotropy energy (MAE). Our calculations show that Mn3Br8 monolayer is a ferromagnetic (FM) half-metal with Curie temperature of 130 K, large MAE of - 2.33 meV per formula unit, and atomic magnetic moment of 13/3μB for the Mn atom. Additionally, Mn3Br8 monolayer maintains to be FM under small biaxial strain, whose Curie temperature under 5% compressive strain is 160 K. Additionally, both biaxial strain and carrier doping make the MAE increases, which mainly contributed by the magneto-crystalline anisotropy energy (MCE). Our designed defective structure of MnBr2 monolayer provides a simple but effective way to achieve ferromagnetism with large MAE in 2D materials.

[Impact of history of hypertension and blood pressure levels on the risk of thromboembolism in nonvalvular atrial fibrillation patients]

Objective: To investigate the impact of history of hypertension and blood pressure levels on the thromboembolism risk in the setting of nonvalvular atrial fibrillation (NVAF). Methods: China Atrial Fibrillation Registry Study prospectively enrolled 25 512 atrial fibrillation (AF) patients between August 2011 and December 2018. After exclusion of patients with valvular AF, hypertrophic cardiomyopathy, receiving anticoagulation or ablation therapy at the enrollment, 7 757 patients were included in analysis. The primary endpoint was the time to the first occurrence of ischemic stroke or systemic embolism. Cox proportional hazards models were performed to evaluate whether a history of hypertension or blood pressure levels were independently associated with thromboembolism. Results: During a mean follow up of (35±25) months, 455 （5.9%）thromboembolic events occurred. The crude incidence rate of thromboembolism in patients with a history of hypertension was higher than that in patients without hypertension (2.38 vs. 1.35 per 100 patient-years, χ²=16.8，Log-rank P<0.001). Patients were further divided into 4 groups according to systolic blood pressure (SBP) levels at baseline, the crude incidence rate of thromboembolism significantly increased in proportion to the elevation of SBP levels (χ²=17.9，Log-rank P<0.001). However, there was no significant difference in thromboembolism risk among 4 groups stratified by diastolic blood pressure (DBP) levels (χ²=0.6，Log-rank P=0.907). Multivariable regression analysis showed that history of hypertension was independently associated with a 27% higher risk of thromboembolism (HR=1.27, 95%CI 1.01-1.61, P=0.045). Patients with SBP≥140 mmHg (1 mmHg=0.133 kPa) was associated with 36% higher risk of thromboembolism than patients with SBP<120 mmHg (HR=1.36, 95%CI 1.02-1.82, P=0.036). However, patients with SBP 120-129 mmHg or 130-139 mmHg were not at a higher risk of thromboembolism as compared to the patients with SBP<120 mmHg (SBP 120-129 mmHg: HR=1.23, 95%CI 0.90-1.67, P=0.193; SBP 130-139 mmHg: HR=1.30, 95%CI 0.95-1.77, P=0.098). In addition, DBP levels were not independently associated with the increased thromboembolism risk. Conclusion: A history of hypertension and SBP≥140 mmHg are independent predictors of thromboembolism risk in patients with NVAF. These results indicate that intensive efforts to lower SBP below 140 mmHg might be an important strategy to reduce the risk of stroke in patients with NVAF.

High Curie temperature and carrier mobility of novel Fe, Co and Ni carbide MXenes

Two-dimensional (2D) magnets with room temperature ferromagnetism and semiconductors with moderate band gap and high carrier mobility are highly desired for applications in nanoscale electronics and spintronics. By performing the first-principles calculations, we investigate novel Fe, Co, Ni carbide based pristine (M₂C) and functionalized (M₂CT₂, T: F, O, OH) MXenes. Our calculations show that Fe₂C, Co₂C, Ni₂C, Fe₂CF₂, Fe₂CO₂, Fe₂C(OH)₂, Co₂CF₂, Co₂C(OH)₂ and Ni₂CF₂ are dynamically and mechanically stable. More importantly, Fe₂C, Co₂C, Fe₂CF₂ and Fe₂C(OH)₂ exhibit intrinsic ferromagnetism (magnetic moments 2-5μ_B per unit cell). Monte Carlo simulations suggest high Curie temperatures of 590 and 920 K for Fe₂C and Fe₂CF₂, respectively, at the HSE06 level owing to the large spin magnetic moments and strong ferromagnetic coupling. Based on the deformation potential theory, we predict high and anisotropic hole mobility (0.2-1.4 × 10⁴ cm² V^-1 s^-1) for semiconducting Fe₂CO₂ and Co₂C(OH)₂. Additionally, Ni₂CF₂ demonstrates highly anisotropic electron mobility together with a direct band gap. Our results further show the effectiveness of surface functionalization in modulating the electronic and magnetic properties and broadening the properties of MXenes to achieve long-range intrinsic ferromagnetism well above room temperature and high carrier mobility.

[Relationship between C-reactive protein level and incidence of left atrial spontaneous echocardiographic contrast in patients with nonvalvular atrial fibrillation]

Objective: To investigate the relationship between high sensitivity C-reactive protein (hs-CRP) level and incidence of left atrial spontaneous echocardiographic contrast (LASEC) in the patients with nonvalvular atrial fibrillation (AF). Methods: Four hundred and ninety consecutive patients with nonvalvular atrial fibrillation who underwent radiofrequency ablation for the first time from January 1, 2018 to June 30, 2018 in the Department of Cardiology, Beijing Anzhen Hospital were enrolled. According to the results of transesophageal echocardiography before radiofrequency ablation, patients were divided into the group without LASEC (n=338) and the group with LASEC (n=152). hs-CRP was determined by latex enhanced immunoturbidimetry. The relationship between hs-CRP and LASEC in patients with nonvalvular atrial fibrillation was investigated by univariate and multivariate logistic analysis. Results: LASEC was detected in 152 (31%) of 490 patients. Significant differences in age, type of atrial fibrillation, previous embolic events, fibrinogen, D-dimer, the left atrial anteroposterior diameter and CHA(2)DS(2)-VASc scores were found between patients with and without LASEC (all P<0.05). Compared with the group without LASEC, the serum hs-CRP level was significantly higher in the group with LASEC (3.16 (1.30, 5.23) mg/L vs. 0.67 (0.37, 1.48) mg/L, P<0.001). Multivariate logistic regression analysis showed that hs-CRP (OR=1.136, 95%CI 1.060 - 1.217, P<0.001) and D-dimer (OR=1.040, 95%CI 1.011 - 1.070, P=0.007) were independent determinants for LASEC in this patient cohort. Conclusions: hs-CRP is an independent determinant for LASEC in patients with nonvalvular atrial fibrillation. Inflammation may thus be involved in the formation of prethrombotic state in patients with nonvalvular atrial fibrillation.

Bimetallic chips for a surface plasmon resonance instrument

In this work we have replaced a commonly used Au film with an Au/Ag bimetallic film working as the sensing chip in the commercial surface plasmon resonance (SPR) instrument, Biacore 3000. The bimetallic chip gives out sharper SPR dip than that by the chip made of an Au film. The applicability and stability of the bimetallic chip on the Biacore 3000 are tested by real-time monitoring of biological coupling processes between sulfamethoxazole (SMX) and anti-SMX, which is useful in rapid detection of contaminations in food products. The bimetallic chip performs stably in 6 times' usage and regeneration. Our experiment is helpful to push the bimetallic film into real applications in commercial SPR instruments.

Preliminary research on myosin light chain kinase in rabbit liver

AIM: To study preliminarily the properties of myosin light chain kinase (MLCK) in rabbit liver.

METHODS: The expression of MLCK was detected by reverse transcription-polymerase chain reaction (RT-PCR); the MLCK was obtained from rabbit liver, and its activity was analyzed by γ-³² P incorporation technique to detect the phosphorylation of myosin light chain.

RESULTS: MLCK was expressed in rabbit liver, and the activity of the enzyme was similar to rabbit smooth muscle MLCK, and calmodulin- dependent. When the concentration was 0.65 mg •L¯¹, the activity was at the highest level.

CONCLUSION: MLCK expressed in rabbit liver may catalyze the phosphorylation of myosin light chain, which may play important roles in the regulation of hepatic cell functions.