Layered double hydroxides (LDHs) have emerged as promising electrodes materials for the methanol oxidation reaction. Here, we report on the preparation of different LDHs with the hydrothermal process. The effect of the divalent cation (i.e., Ni, Co, and Zn) on the electrochemical performance of methanol oxidation was investigated. Moreover, nanocomposites of LDHs and carbon xerogels (CX) supported on nickel foam (NF) substrate were prepared to investigate the role of carbon xerogel. The results show that NiFe-LDH/CX/NF is an efficient electrocatalyst for methanol oxidation with a current density that reaches 400 mA·m−2 compared to 250 and 90 mA·cm−2 for NiFe-LDH/NF and NF, respectively. In addition, all LDH/CX/NF nanocomposites show excellent stability for methanol oxidation. A clear relationship is observed between the electrodes crystallite size and their activity to methanol oxidation. The smaller the crystallite size, the higher the current density delivered. Additionally, the presence of carbon xerogel in the nanocomposites offer 3D interconnected micro/mesopores, which facilitate both mass and electron transport.

Background: The long-term survival of patients on hemodialysis (HD) is dependent on adequate HD which depends on quality and degree of functionality of vascular access. The aim of our study is to detect the role of color Doppler ultrasonography in evaluation of arteriovenous fistula (AVF). Materials and methods: Between January 2017 and October 2017, 60 patients had complicated AVF at Qena General Hospital & Qena University Hospital as primary and tertiary centers respectively with the same age group between 18 and 50 years old, had no diabetes mellitus were evaluated using color duplex-Doppler ultrasound (CDUS) after AVF maturation for detection of complications and comparison between primary and tertiary centers of its incidence. Results: The overall results revealed that 11 patients from 30 patients that had been referred to tertiary centers have complicated AVF (36.7%), and 19 patients had no shunt complication (63.3%). Twenty-two patients from 30 patients that had been referred to primary HD centers had complicated shunts. Thrombosis at tertiary centers represents 13.3%, stenosis 3.3% (1 patient), aneurysmal formation had 6.6% for (2 patients), hematoma 6.6%(2 patients), infection 3.3% (1 patient), venous hypertension 3.3% (1 patient), thrombosis and hematoma at primary centers 16.6% (5 patients for each), aneurysmal formation and infection 13.3% for each, and stenosis 10%. Conclusions: CDUS is a readily-available, non-invasive, risk-free, bedside technique that allows precise anatomic knowledge, qualitative, and quantitative data of the upper limb vascular system which greatly help in preoperative planning of AVF creation, assessment of prime time for puncture (maturation), early detection of complications, and choice of appropriate therapeutic procedure for their treatment.

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