Eggshell-Like Carbon Microspheres with Curvature Scheme: Distorted Energy Band and Atomic Charge Waves-Driven High Performance for Zinc-Air Battery.

A metal-free nanocarbon with an eggshell structure is synthesized from chitosan (CS) and natural spherical graphite (NSG) as a cathode electrocatalyst for clean zinc-air batteries and fuel cells. It is developed using CS-derived carbons as an eggshell, covering NSG cores. The synthesis involves the in situ growth of CS on NSG, followed by ammonia-assisted pyrolysis for carbonization. The resulting catalyst displays a curved structure and completely coated NSG, showing superior oxygen reduction reaction (ORR) performance. In 1 M NaOH, the ORR half-wave potential reached 0.93 V, surpassing the commercial Pt/C catalyst by 50 mV. Furthermore, a zinc-air battery featuring the catalyst achieves a peak power density of 167 mW cm-2 with excellent stability, outperforming the Pt/C. The improved performance of the eggshell carbons can be attributed to the distorted energy band of the active sites in the form of N-C moieties. More importantly, the curved thin eggshells induce built-in electric fields that can promote electron redistribution to generate atomic charge waves around the N-C moieties on the carbon shells. As a result, the high positively charged and stable C+ sites adjacent to N atoms optimize the adsorption strength of oxygen molecules, thereby facilitating performance.

Trace Tungsten Microalloying PtCuCo Medium Entropy Alloys: Substructure Reconstruction-Triggered High-Performance for PEMFC.

Refractory metals (W, Nb, or Mo) microalloying Pt-based alloys with unprecedented performance may serve as advanced electrocatalysts for proton exchange membrane fuel cells (PEMFCs). These alloys are endowed with unique stabilizing substructures or lattice defects through the microalloying effect. Herein, trace W microalloying PtCuCo medium entropy alloys (W-PtCuCo) are reported via a stepwise synthesis strategy, starting with home-made Cu nanowires as sacrificial templates by anhydrous solid-phase milling route, and then followed by galvanic replacement-assisted solvothermal in ethylene glycol (EG). In PEMFC tests, the obtained W-PtCuCo exhibits an ultrahigh peak power density and mass power density (relative to cathode) reaching 2.09 W cm-2 and 20.9 W mgPt -1 , respectively. During the accelerated degradation test (ADT), the mass activity just lost only 3% after 30 k cycles, much better than the above benchmark catalyst. The microalloying-dependent performances shall be attributed to the presence of abundant stepped surfaces, twisted edges, and other lattice defects terminated by W via substructure reconstruction that indeed alters the electronic structure and strain level of the alloys. This work first provides an atomic-level insight into the microalloying-dependent electrocatalytic performance of Pt-based alloys, which is of great significance for developing next-generation efficient catalysts for PEMFC.

Apoptosis of human kidney epithelial cells induced by high oxalate and calcium oxalate monohydrate is apurinic/apyrimidinic endonuclease 1 pathway dependent and contributes to kidney stone formation.

Kidney stone formation is a very complex process. Multiple molecules and proteins are involved in its formation. High level of oxalate and calcium oxalate monohydrate (COM, 200 mg/ml) crystals are key elements for this process, but the exact mechanism needs to be defined. HOA has been shown to cause renal cell injury through oxidative stress, leading to potential crystal deposition in the kidneys, which induced apoptosis of kidney epithelial cells. Recent reports indicated that apurinic/apyrimidinic endonuclease 1 (APE1) is involved in DNA repair and redox regulation of transcriptional factors, and APE1-dependent apoptosis is observed in various nephropathy models. Therefore, we investigated the changes of APE1 protein expression in the human kidney epithelial cell line (HK-2) by exposing them to high oxalate and COM in various conditions. The results showed that HOA triggers intracellular reactive oxygen species (ROS) and apoptosis of HK-2 cells. This process was mediated by the abnormal expression, modification, and redistribution of APE1 protein in HK-2 cells. The antioxidant N-acetylcysteine reversed this effect. Our results demonstrated a novel molecular mechanism related to renal epithelial cell injury and kidney stone formation.

A Novel Ureterorenoscope for the Management of Upper Urinary Tract Stones: Initial Experience from a Prospective Multicenter Study.

PURPOSE: This prospective single-arm multicenter clinical trial was conducted to evaluate the safety and efficacy of the Sun's tip-flexible semirigid ureterorenoscope (tf-URS) when used for managing upper urinary tract stones. PATIENTS AND METHODS: Data from patients who underwent ureteroscopy using the tf-URS for proximal and renal stone removal were prospectively collected from seven Chinese clinical centers. The primary study end point was the stone clearance at the 2-week follow-up. Other data associated with the procedure were also collected. RESULTS: Between October and December of 2014, this study enrolled a total of 254 patients; among which, 235 patients were eligible for ureteroscopy, 216 of whom were treated using the tf-URS. Among all treated patients, 135 had proximal ureteral stones (group 1) while 81 had renal stones (group 2). The overall success rate of endoscope advancement was 91.9% (216/235). The mean fragmentation times were 17.5±12.6 minutes and 23.3±15.1 minutes for groups 1 and 2, respectively, and corresponded to an experience-dependent increase in fragmentation speed in both groups. The mean operative times were 31.9±15.5 minutes and 39.5±2 0.3 minutes for groups 1 and 2, respectively. The access rate to renal stones in group 2 was 96% (76/81). All treated patients were assessed during a 2-week follow-up period. The stone-free rates at the 2-week follow-up for groups 1 and 2 were 98.7% (133/135) and 91.3% (74/81), respectively. Adverse events were observed in 7.3% (16/216) of the patients; however, all were classified as Grade I or Grade II complications. CONCLUSIONS: Based on our initial experience in the current study, the tf-URS can be safely and effectively used to manage proximal ureteral and renal stones with a low rate of complications. Future studies are needed to focus on a transverse comparison between the tf-URS and conventional ureteroscopes.