Corrosion and in vitro cytocompatibility investigation on the designed Mg-Zn-Ag metallic glasses for biomedical application

In the present work,seven Mg-Zn-Ag alloys with the nominal composition of Mg_(96-x)Zn_(x)Ag_(4)(x=17,20,23,26,29,32,35 in at.%)were prepared by induction melting and single-roller melt-spinning.The X-ray diffraction(XRD)analyses indicate the metallic glasses with three composition of Mg_(73)Zn_(23)Ag_(4),Mg_(70)Zn_(26)Ag_(4),and Mg_(67)Zn_(29)Ag_(4)were obtained successfully.The differential scanning calorimetry(DSC)measurement was used to obtain the characteristic temperature of Mg-Zn-Ag metallic glasses for the glass-forming ability analysis.The maximum glass transition temperature(Trg)was found to be 0.525 with a composition close to Mg_(67)Zn_(29)Ag_(4),which results in the best glass-forming ability.Moreover,the immersion test in simulated body fluid(SBF)demonstrate the relative homogeneous corrosion behavior of the Mg-Zn-Ag metallic glasses.The corrosion rate of Mg-Zn-Ag metallic glasses in SBF solution decreases with the increase of Zn content.The sample Mg_(67)Zn_(29)Ag_(4)has the lowest corrosion rate of 0.19mm/yr,which could meet the clinical application requirement well.The in vitro cell experiments show that the Madin-Darby canine kidney(MDCK)cells cultured in sample Mg_(67)Zn_(29)Ag_(4)and its extraction medium have higher activity.However,the Mg-Zn-Ag metallic glasses exhibit obvious inhibitory effect on human rhabdomyosarcoma(RD)tumor cells.The present investigations on the glass-forming ability,corrosion behavior,cytocompatibility and tumor inhibition function of the Mg-Zn-Ag based metallic glass could reveal their biomedical application possibility.

Investigation on the crystal structure and mechanical properties of the ternary compound Mg_(11-x)Zn_(x)Sr combined with experimental measurements and first-principles calculations

A new ternary compound,Mg_(11-x)Zn_(x)Sr in the Mg-Zn-Sr system was observed and studied using Scanning Electron Microscopy(SEM),Energy-Dispersive Spectroscope(EDS),X-Ray Diffraction(XRD)and Transmission Electron Microscopy(TEM).The XRD patterns were refined by the Rietveld refinement method and the results revealed that the crystallized Mg_(11-x)Zn_(x)Sr phase belonged to tetragonal I41/amd space group and had the Cd_(11)Ba prototype.The Mg atoms were successfully doped into Zn_(11)Sr crystal lattice by occupying Zn atomic sites.Moreover,the Rietveld refinement and computational results demonstrated a gradual decrease in the a-axis and c-axis lattice parameters with decreasing concentration levels of Mg coordination substitution in the lattice of Mg_(11-x)Zn_(x)Sr compound.The elastic constants and modulus of the Mg_(11-x)Zn_(x)Sr compounds calculated by first-principles calculations(FPC)indicated they were increased with the increasing of Zn content.The variation of hardness,D-band widths and the total density of states for Mg_(11-x)Zn_(x)Sr compounds with Zn content was discussed.

中国大陆麻醉住院医师毕业后教育的探讨

经过近几年在全国部分省市试点后,2015年教育部和卫计委正式通知在全国范围内改变医学教育的现有模式,新的规范化培养（简称规培）已经逐步开展并日渐规范。各专科住院医师规范化培训的目的是培养具有现代医学素质的专职人员,能够胜任现代医学的临床要求。同时对住院医师进行评估和考核已经日趋重要,同样需要通过规范化的方式进行。现将美国麻醉住院医师培训考核模式与国内麻醉住院医师考核方式进行比较。

Monitoring cerebral ischemia during carotid endarterectomy and stenting

Current therapy for carotid stenosis mainly includes carotid endarterectomy and endovascular stenting,which may incur procedure-related cerebral ischemia.Several methods have been employed for monitoring cerebral ischemia during surgery,such as awake neurocognitive assessment,electroencephalography,evoked potentials,transcranial Doppler,carotid stump pressure,and near infrared spectroscopy.However,there is no consensus on the gold standard or the method that is superior to others at present.Keeping patient awake for real time neurocognitive assessment is effective and essential;however,not every surgeon adopts it.In patients under general anesthesia,cerebral ischemia monitoring has to rely on non-awake technologies.The advantageous and disadvantageous properties of each monitoring method are reviewed.

Cerebral ischemia during surgery:an overview

Cerebral ischemia is the pathophysiological condition in which the oxygenated cerebral blood flow is less than what is needed to meet cerebral metabolic demand.It is one of the most debilitating complications in the perioperative period and has serious clinical sequelae.The monitoring and prevention of intraoperative cerebral ischemia are crucial because an anesthetized patient in the operating room cannot be neurologically assessed.In this paper,we provide an overview of the definition,etiology,risk factors,and prevention of cerebral ischemia during surgery.

Monitoring cerebral ischemia using cerebral oximetry:pros and cons

Introduction The high metabolic rate of oxygen in the human brain accounts for its extreme susceptibility to ischemic-hypoxic conditions.Ischemic brain injury such as stroke is a potential neurologic complication in a variety of surgeries,including cardiac surgery,neurosurgery,and vascular surgery,particularly in patients at high risk for ischemic stroke^（[2]）.In addition,ischemic brain injury accounts for

Monitoring cerebral ischemia during cerebrovascular surgery

Patients undergoing intracranial cerebrovascular surgery under general anesthesia are at risk of cerebral ischemia due to the nature of the surgery and/or the underlying cerebrovascular occlusive disease.It is thus imperative to reliably and continuously monitor cerebral perfusion during this type of surgery to timely reverse ischemic processes.The aim of this review is to discuss the techniques currently available for monitoring cerebral ischemia during cerebrovascular surgery with a focus on the advantages and disadvantages of each technique.