A first-principles study of rare earth quaternary Heusler compounds: RXVZ (R = Yb, Lu; X = Fe, Co, Ni; Z = Al, Si).

Rare earth equiatomic quaternary Heusler (EQH) compounds with chemical formula RXVZ (R = Yb, Lu; X = Fe, Co, Ni; Z = Al, Si) have recently attracted much attention since these materials are easily prepared and they also provide interesting properties for future spintronic applications. In this work, rare Earth-based EQH compounds in three types of structures are theoretically investigated through first-principles calculations based on density functional theory. We find that most of the studied rare Earth EQH compounds exhibit magnetic ground states including ferro-, antiferro-, and ferri-magnetic phases. Owing to the nearly closed shell f orbital in Lu and Yb, the spin magnetic moments mainly come from the 3d transition metal elements. In particular, in the type I structure, a large portion (7 out of 12) of EQH compounds are ferromagnetic half-metals (HMs) with integer magnetic moments ranging from 1 to 3 µB. In the type II structure, YbFeVAl is found to be a rare case of antiferro-magnetic (AFM) half-metal with zero total magnetic moments. Surprisingly, we also discover an unusual magnetic semiconductor LuCoVSi in the type III structure with a total spin magnetic moment of 3.0 µB and an indirect band gap of 0.2 eV. The structural and magnetic stabilities such as formation energy, magnetization energy as well as the mechanical stabilities such as the bulk, shear, and Young's moduli, and Poisson's, and Pugh's ratios of these EQH compounds are also investigated. Most of the studied compounds exhibit mechanical stability under the mechanical stability criteria and show elastic anisotropy. Our work provides guidelines for experimental researchers to synthesize useful materials in future spintronic applications.

An Updated Healthcare System-Wide Clinical Pathway for Managing Patients With Chest Pain and Acute Coronary Syndromes.

Clinical pathways reinforce best practices and help healthcare institutions standardize care delivery. The NewYork-Presbyterian/Columbia University Irving Medical Center has used such a pathway for the management of patients with chest pain and acute coronary syndromes for almost 2 decades. A multidisciplinary panel of stakeholders serially updates the algorithm according to new data and recently published guidelines. Herein, we present the 2019 version of the clinical pathway. We explain the rationale for changes to the algorithm and describe our experience expanding the pathway to all the 8 affiliated institutions within the NewYork Presbyterian healthcare system.

Partial nephrectomy without renal ischemia using an electromagnetic thermal surgery system in a porcine model.

OBJECTIVE: To test the feasibility of partial nephrectomy using needle arrays under alternating current (AC) electromagnetic field without renal artery clamping. METHODS: We performed an experimental study for partial nephrectomy without renal artery clamping in a porcine model, comparing a new thermal surgery system consisting of an AC electromagnetic field generator and stainless steel needle arrays (using 10 pigs) vs an ultrasonic Harmonic Scalpel (on 8 pigs). Two cm of the upper pole of the kidneys were resected, and then the feasibility, operation time, blood loss, biochemical parameters, pathology, and complications were observed for 14 days. RESULTS: There was no difference by weight in the mean percentage of kidney removed between the 2 groups (8.1 ± 3.4% vs 12.7 ± 5.5%). The estimated blood loss for the partial nephrectomy with electromagnetic thermal surgery system was significantly less compared to the ultrasonic Harmonic Scalpel (53.0 ± 73.0 vs 188.8 ± 49.3 mL). Transection time was shorter with the electromagnetic thermal surgery system (10 vs 12 minutes). Bleeding from the cut surface after partial nephrectomy was noted in 2 pigs (electromagnetic surgery group) and 8 pigs (control group); all the bleeding was controlled with additional monopolar electrocoagulation and sutures. No urinoma was identified in either group when a second laparotomy was performed 2 weeks later. CONCLUSION: Our study of a partial nephrectomy in a porcine model demonstrates that the heat generated by the electromagnetic thermal surgery system is sufficient to coagulate renal parenchyma and to seal off the blood vessels without pedicle clamping.

Mood improvement after surgery for obstructive sleep apnea.

OBJECTIVE: Patients with obstructive sleep apnea (OSA) may experience unfavorable psychologic symptoms such as depression and anxiety. The aim of this study was to confirm this hypothesis and to investigate whether the psychologic symptoms among OSA patients can be relieved by surgical intervention. STUDY DESIGN: Prospective, longitudinal intervention study. METHODS: The 5-Item Mental Health scale (MH-5) was used to evaluate the postoperative changes of mood after extended uvulopalatal flap (EUPF) surgery on 84 Taiwanese patients with OSA. The preoperative and postoperative MH-5 data obtained from these patients were compared with a Taiwanese population norm. RESULTS: Before surgery, the MH-5 scores of the OSA patients were significantly worse than the Taiwanese population norm of 72.8 (P <.0001). Postoperatively, mean MH-5 scores significantly increased from 61.8 +/- 16.0 to 70.0 +/- 15.8 (P =.0006). The effect size of this score change was 0.51, indicating a moderate degree of mood improvement. However, this score was still inferior to that of the population norm (P =.0045). The mood improvement was not significantly associated with the changes in either sleep apnea events or the level of sleepiness. Neither the changes in respiratory disturbance index (P =.4382), maximum arterial oxygen saturation (P =.4866), nor the change in Epworth Sleepiness Scale scores (P =.4951) were predictive of the MH-5 score improvement (R = 0.07). CONCLUSIONS: This study demonstrated that patients with OSA had a higher level of anxiety, depression, and probable behavior or personality changes than the population norm. EUPF surgery could significantly improve the mood status among OSA patients; the effect of surgery was mild but clinically relevant. However, the extent of mood improvement experienced by OSA patients receiving operations may not simply be attributable to the changes in sleep apnea events or a reduced level of sleepiness.