Pneumocephalus Following Combined Spinal-Epidural Anesthesia: A Case Report Analysis

Background: Combined spinal-epidural anesthesia (CSEA) is widely used in clinical anesthesia due to its rapid onset, reliable anesthetic effect, and strong controllability. Although advancements in technique have reduced the frequency and severity of common complications, reports of rare and serious complications such as pneumocephalus, remain scarce. Case Report: This article presents a case of pneumocephalus following CSEA in a middle-aged female patient undergoing surgery for an intrauterine space-occupying lesion. The patient experienced severe headache postoperatively, and imaging confirmed the presence of intracranial air. After receiving active symptomatic treatment, the patient recovered and was discharged. Conclusion: This case underscores the importance of adhering to standard anesthesia protocols and increasing awareness of rare CSEA complications, particularly the risk of pneumocephalus. Early recognition and timely management are crucial. There is a need to further enhance training and research in anesthetic procedures to improve clinical anesthesia quality and ensure patient safety.

High-throughput calculations combining machine learning to investigate the corrosion properties of binary Mg alloys

Magnesium(Mg)alloys have shown great prospects as both structural and biomedical materials,while poor corrosion resistance limits their further application.In this work,to avoid the time-consuming and laborious experiment trial,a high-throughput computational strategy based on first-principles calculations is designed for screening corrosion-resistant binary Mg alloy with intermetallics,from both the thermodynamic and kinetic perspectives.The stable binary Mg intermetallics with low equilibrium potential difference with respect to the Mg matrix are firstly identified.Then,the hydrogen adsorption energies on the surfaces of these Mg intermetallics are calculated,and the corrosion exchange current density is further calculated by a hydrogen evolution reaction(HER)kinetic model.Several intermetallics,e.g.Y_(3)Mg,Y_(2)Mg and La_(5)Mg,are identified to be promising intermetallics which might effectively hinder the cathodic HER.Furthermore,machine learning(ML)models are developed to predict Mg intermetallics with proper hydrogen adsorption energy employing work function(W_(f))and weighted first ionization energy(WFIE).The generalization of the ML models is tested on five new binary Mg intermetallics with the average root mean square error(RMSE)of 0.11 eV.This study not only predicts some promising binary Mg intermetallics which may suppress the galvanic corrosion,but also provides a high-throughput screening strategy and ML models for the design of corrosion-resistant alloy,which can be extended to ternary Mg alloys or other alloy systems.

The interface structure and property of magnesium matrix composites:A review

Magnesium matrix composites have garnered significant attention in recent years owing to their exceptional lightweight properties and notable potential in various engineering applications.The interface generally acts as a“bridge”between the matrix and reinforcement,playing crucial roles in critical processes such as load transfer,failure behavior,and carrier transport.A deep understanding of the interfacial structures,properties,and effects holds paramount significance in the study of composites.This paper presents a comprehensive review of prior researches related to the interface of Mg matrix composites.Firstly,the different interfacial structures and interaction mechanisms encompassing mechanical,physical,and chemical bonding are introduced.Subsequently,the interfacial mechanical properties and their influence on the overall properties are discussed.Finally,the paper addresses diverse interface modification methods including matrix alloying and reinforcement surface treatment.

Activation of dislocations in Mg with solute Y

Mg-Y cast alloy shows excellent ductility(elongation to failure>15%)compared with pure Mg and commercial Mg cast alloys.By monitoring the microstructure evolution during an in situ tensile test of a Mg-2.5 wt%Y alloy,we identify the activation of prismatic<c>slip,which is rare in Mg.Synchrotron X-ray micro-beam Laue diffraction(μ-Laue)and transmission electron microscopy revealed the morphology of prismatic<c>slip bands and individual<c>dislocations.Density functional theory and molecular dynamics calculations indicate that solute Y can significantly reduce the stacking fault energy(SFE)along<c>direction on prismatic plane in Mg lattice and thus facilitate the nucleation of<c>dislocations during deformation.The presence of free<c>dislocations in the Mg lattice can also lead to nucleation of{10–12}twins even under unfavorable geometric conditions.

The effect of LPSO phase on the high-temperature oxidation of a stainless Mg-Y-Al alloy

In this study,we investigated the oxidation of the Mg-11Y-1Al alloy at 500℃in an Ar-20%O2environment.Multiscale analysis showed the network-like long-period stacking ordered(LPSO)phase transformed into needle-like LPSO and polygonal Mg24Y5 phases,leading to the formation of a high-dense network of needle-like oxides at the oxidation front.These oxides grew laterally along the oxide/matrix interfaces,forming a thicker,continuous scale that effectively blocked elemental diffusion.Hence,the preferential oxidation along the needle-like LPSO is believed to accelerate the formation of a thicker and continuous oxide scale,further improving the oxidation resistance of the Mg-11Y-1Al alloy.

A Giant Granuloma of the Vocal Process after Double-Lumen Bronchial Catheter Insertion: A Rare Case Report and Literature Review

Background: Double-lumen endotracheal (DLT) is commonly used for one-lung ventilation and lung separation during thoracic surgery. There are case reports of medically induced laryngeal granulomas, mainly in patients after single-lumen endotracheal (SLT) tube intubation and tracheotomy, and giant granulomas of the vocal cords due to double-lumen bronchial tube insertion have rarely been reported. Case presentation: A 49-year-old female patient underwent single-port thoracoscopy after DLT intubation as well as a wedge resection of the lower lobe of the left lung, which caused giant vocal process granulomas (VPGs) postoperatively. Based on a retrospective analysis of the general condition, current medical history, past medical history, and visual laryngoscopic observation of the vocal folds tissue, which ruled out preoperative vocal fold granuloma formation, we hypothesized that double-lumen bronchial catheter intubation may have been the primary cause of her vocal fold granuloma formation. Conclusions: Giant granuloma of the vocal folds after DLT insertion is a rare postoperative complication;therefore, if DLT intubation is to be performed, the anesthesiologist should choose an appropriate intubation plan and deal with it promptly to avoid the risk factors to ensure that the patient’s perioperative period is safe and smooth. In addition, if postoperative complications are encountered, they should be followed up and observed on time.

Characterization on the formation of porosity and tensile properties prediction in die casting Mg alloys

The 3D visualization of the porosity in high-pressure die casting(HPDC)Mg alloys AZ91D and Mg4Ce2Al0.5Mn(EA42)was investigated by X-ray computed tomography.It was demonstrated that the volumetric porosity at the near-gate location for alloy EA42 was significantly higher than that far from the gate location.This difference resulted from the low valid time during intensified casting pressure conditions.Specimens of alloy EA42 exhibited a narrow pore distribution in the side view(~0.5 mm)compared to the wide distribution(~1.8 mm)of alloy AZ91D,which was mainly attributed to the formation mechanism of the defect band.The formation of microporosity in the defect band of alloy EA42 was inhibited because of the significant latent heat released by a large amount of the Al11Ce3phase segregated in the defect band during solidification.Additionally,an effective estimator(Z-Propagation)was introduced,which is proposed to predict the projected area fraction of the porosity(f)involved during tensile failure with better effectiveness compared with traditional methods based on the actual fractured surface.By coupling the Z-Propagation method with the critical local strain model,the logarithmic fracture strain and true fracture stress of the specimens were predicted within 3.03%and 1.65%of the absolute value of the average relative error(AARE),respectively.

Microstructural evolution of Mg-Al-Re alloy reinforced with alumina fibers

Few studies were reported on the phases'relationships of AE44(Mg-4.0Al-4.1RE-0.3Mn,wt.%)and its composites.In this work,AE44 alloy and Saffil(6-Al2O3)/AE44 Metal matrix composite(MMC)were both prepared by slow shot high pressure die casting(SS-HPDC)technology and their phase constitutions were all studied in detail using experimental techniques combined with CALPHAD(Calculation of Phase Diagram)modeling.The results revealed that the alloy consists of the a-Mg matrix,A1hRE3 intermetallic phase,and one trace phase AI3RE,while the composite contains five major phases:a-Mg,5-AI2O3,AI3RE,MgO and Mg2Si.and two trace phases of A12RE and AI11RE3,respectively.A1hRE3 is partly derived from ALRE,while A13RE is a product of the peritectoid reaction between the two precipitates.The presence of MgO and Mg2Si is due to the interfacial reaction between the SiO2 binder in the fiber preforms and the molten magnesium during infiltration.The use of SiO2 binder in the preform manufacturing was limited/minimized to reduce the MgO formation in the MMC casting process,which can be detrimental to the fatigue performance of the MMC materials.

Investigation of the alloying effect on deformation behavior in Mg by Visco-Plastic Self-Consistent modeling

Alloying elements can drastically alter the deformation behavior of Mg.In the present work,Visco-Plastic Self-Consistent(VPSC)modeling was employed to investigate the effect of alloying elements on Mg’s tensile behavior,in particular the relative activity of different slip and twinning modes.Mg-0.47 wt.%Ca,Mg-2 wt.%Nd,and AZ31 extruded alloys were deformed by micro-tensile tests in a scanning electron microscope(SEM).Texture and grain size measured by electron backscatter diffraction(EBSD)were used as the input for VPSC.After parameter optimization,the VPSC model successfully reproduced the stress-strain curve of each alloy.Simulation results indicate that the slip/twinning activity in the three alloys are different.Mg-0.47 wt.%Ca shows strong extrusion texture,and prismatic slip was quite active during its tensile deformation.In contrast,Mg-2 wt.%Nd shows weak extrusion texture,and basal slip was dominant.This alloy also developed more twinning activity than the other two alloys.AZ31 shows strong extrusion texture similar as Mg-0.47 wt.%Ca,but prismatic slip was less active in it.The slip/twinning activity revealed by the VPSC model can explain the difference in the tensile behavior of the three alloys.

Designing strategy for corrosion-resistant Mg alloys based on film-free and film-covered models

Mathematical models were proposed to clarify the effect of alloying on corrosion of magnesium alloys based on film-free and film-covered status. The models are applicable to explain the “barrier effect” by cathodes and the “analogous Hall-Petch relationship” between corrosion rates and grain size. The slope of corrosion rates versus alloying content is determined by the dissolution ability of film-free substrate and the hindering effects by corrosion product film. Designing strategy for corrosion-resistant Mg alloys is established.

Twin recrystallization mechanisms in a high strain rate compressed Mg-Zn alloy

Static recrystallization of a high strain rate compressed Mg-1 Zn(wt.%)alloy was investigated using electron backscattered diffraction(EBSD).A novel 53°1010 structure was observed in the as-deformed alloy,which showed a{1012}-{1012}double twin relationship with the matrix.When the as-deformed alloy was annealed at 200°C,the{1011}compression twins and{1011}-{1012}double twins showed a higher priority to recrystallize.In addition,the coarse{1012}tension twins and their inner double twins were preferentially to recrystallize,while the lenticular tension twins had little impact on the recrystallization.Therefore,obtaining more compression twins or coarse twins instead of lenticular tension twins can be an effective approach to manipulate recrystallization process in deformed Mg alloys.

Effective femtosecond laser shock peening on a Mg-3Gd alloy at low pulse energy 430 μJ of 1 kHz

In this paper,microstructure evolution and hardness of Mg-3 Gd alloy treated by femtosecond(fs)laser shock peening(LSP)with direct and confined ablation m odes were investigated in detail.Under a relatively low pulse energy of 430μJ with a repetition of 1 kHz,the surface hardness of sample has been enhanced by 70%effectively.Comp a r e d with ns-LSP with pulse fluence of 71.7J/cm2,fs-LSP with pulse fluence of 34.2 J/cm2 is superior in the hardness increment,both of which are in the same order of magnitude.A distinct grain refinement of surface layer has been discovered and results in the increase of hardness.Nonuse of absorption and confining layers and the employment of the industry commercial fs laser with high repetition can inspire big potential L S P application in special metal material.©2019 Published by Elsevier B.V.on behalf of Chongqing University.

In-situ monitoring of dynamic behavior of catalyst materials and reaction intermediates in semiconductor catalytic processes

Semiconductor photocatalysis, as a key part of solar energy utilization, has far-reaching implications for industrial, agricultural, and commercial development. Lack of understanding of the catalyst evolution and the reaction mechanism is a critical obstacle for designing efficient and stable photocatalysts. This review summarizes the recent progress of in-situ exploring the dynamic behavior of catalyst materials and reaction intermediates. Semiconductor photocatalytic processes and two major classes of in-situ techniques that include microscopic imaging and spectroscopic characterization are presented. Finally, problems and challenges in in-situ characterization are proposed, geared toward developing more advanced in-situ techniques and monitoring more accurate and realistic reaction processes, to guide designing advanced photocatalysts.

A highly degradable Mg-Al-Ca alloy with superior anti-tumor efficacy

Molecule hydrogen(H_(2)) has been used to suppress tumor growth. To employ the H_(2) therapy, it is necessary to use a proper agent for continuous generation of H_(2). As a biodegradable metal, magnesium(Mg) generates H_(2) in an aqueous environment, but the H_(2) release rate is still too low. Here, we design a Mg-Al-Ca(AX) alloy that degrades very rapidly due to the presence of a secondary phase Al_(2)Ca. Having a reduction potential much higher than Mg and any other Mg-based secondary phases, Al_(2)Ca accelerates the corrosion of the Mg matrix by a micro-galvanic process. Al_(2)Ca also enhances the strength and ductility of the AX alloy. AX alloy rods show better anti-tumor efficacy than pure Mg rods in vivo. Moreover, implanted AX alloy rods can be heated under an alternating magnetic field to suppress large-size tumors.This work suggests that the H_(2) therapy using highly degradable Mg alloys may provide an effective cancer treatment.

Kinking-facilitated nano-crystallization in a shock compressed Mg-1Zn alloy

The local deformation behavior and dynamic recrystallization of a shock compressed Mg-1Zn alloy was investigated through EBSD and TEM.Since dislocation slipping and twinning were locally suppressed during high strain-rate deformation,a more flexible kinking deformation was activated to adjusted local orientation and facilitate slipping and twinning within the kinks.Meanwhile,due to the slow heat dissipation that resulted in a local temperature elevating,the kink bands were evolved into deformation bands with recrystallized nano-grains.Such a finding provides a new perspective for kinking-facilitated nanocrystallization in Mg alloys and other anisotropic metallic materials.

Post-fire residual service performance of magnesium alloys reinforced by rare earths

The flammability of magnesium alloys continues to be a significant barrier to their extensive application,and alloying with rare earth elements(REs)is an effective way to enhance the ignition and fire resistance of Mg alloys.Three commercial as-extruded Mg alloys(AZ80 and two Mg-RE alloys:EZ30K and WE43)were directly exposed to flame heating for revealing the evolutions of microstructure and mechanical properties,which is valuable in assessing the post-fire residual service performance of Mg alloy components.Results show that secondary phase dissolution,grain growth,grain boundary melting,alloy melting,and defects generation successively occur during the heating process.After short-term heating for 30 s,the elongation of AZ80 alloy increases significantly by 214%,from 3.82%to 12.01%,with minimal change in strength compared to the initial unheated state.This transformation is attributed to the recovery,grain growth,Mg17Al12 dissolution and dislocation density reduction.Conversely,EZ30K and WE43 alloys exhibit minimal changes in mechanical properties after short-term heating for 60 s,attributed to the pinning effect of REs.However,in subsequent heating states,resolidified microstructure and the presence of defects lead to a noteworthy decrease in both strength and elongation.Among these three alloys,the fire resistance follows this ranking:EZ30K>WE43>AZ80,primarily due to the high thermal conductivity of EZ30K alloy and the thermal stability improved by the addition of REs.

A Review of Magnesium Alloys as Structure–Function Integrated Materials

Magnesium alloys have a significant advantage,lower density over the other structure materials;hence,they have been widely used in various fields such as transportation and aerospace.With the development of research and the enlargement of the research scope,more advantages have been revealed:excellent shielding efficiency,extraordinarily high damping capacity,as well as impressive thermal conductivity.Therefore,Mg alloys have the potential to be various functional materials,such as electromagnetic shielding material,damping material,and thermal conductive material.This review comprehensively summarizes the research progress and the up-to-date summary of Mg alloys as structure–function integrated materials in recent years.Solute atoms,heat treatment,deformation,secondary phase,and temperature,which have a significant influence on the properties of magnesium alloys,are highlighted.We expect this review to be helpful for those who are working on developing structure–function integrated materials with superior comprehensive performance.

PDGPT:A large language model for acquiring phase diagram information in magnesium alloys

Magnesium alloys,known for their lightweight advantages,are increasingly in demand across a range of applications,from aerospace to the automotive industry.With rising requirements for strength and corrosion resistance,the development of new magnesium alloy systems has become critical.Phase diagrams play a crucial role in guiding the magnesium alloy design by providing key insights into phase stability,composition,and temperature ranges,enabling the optimization of alloy properties and processing conditions.However,accessing and interpreting phase diagram data with thermodynamic calculation software can be complex and time-consuming,often requiring intricate calculations and iterative refinement based on thermodynamic models.To address this challenge,we introduce PDGPT,a ChatGPT-based large language model designed to streamline the acquisition of magnesium alloys Phase Diagram information with high efficiency and accuracy.Enhanced by promptengineering,supervised fine-tuning and retrieval-augmented generation,PDGPT leverages the predictive and reasoning capabilities of large language models along with computational phase diagram data.By combining large language models with traditional phase diagram research tools,PDGPT not only improves the accessibility of critical phase diagram information but also sets the stage for future advancements in applying large language models to materials science.

The anodic dissolution kinetics of Mg alloys in water based on ab initio molecular dynamics simulations

The corrosion susceptibility of magnesium(Mg)alloys presents a significant challenge for their broad application.Although there have been extensive experimental and theoretical investigations,the corrosion mechanisms of Mg alloys are still unclear,especially the anodic dissolution process.Here,a thorough theoretical investigation based on ab initio molecular dynamics and metadynamics simulations has been conducted to clarify the underlying corrosion mechanism of Mg anode and propose effective strategies for enhancing corrosion resistance.Through comprehensive analyses of interfacial structures and equilibrium potentials for Mg(0001)/H_(2)O interface models with different water thicknesses,the Mg(0001)/72 H_(2)O model is identified to be reasonable with−2.17 V vs.standard hydrogen electrode equi-librium potential.In addition,utilizing metadynamics,the free energy barrier for Mg dissolution is calculated to be 0.835 eV,enabling the theoretical determination of anodic polarization curves for pure Mg that aligns well with experimental data.Based on the Mg(0001)/72 H_(2)O model,we further explore the effects of various alloying elements on anodic corrosion resistance,among which Al and Mn alloying elements are found to enhance corrosion resistance of Mg.This study provides valuable atomic-scale insights into the corrosion mechanism of magnesium alloys,offering theoretical guidance for developing novel corrosion-resistant Mg alloys.

Review of progress on fabrication technology of Mg matrix composites

Mg matrix composites(Mg MCs)with enhanced mechanical and functional properties,as well as improved elastic modulus,have aroused rising attention from the aerospace,new energy vehicles,and consumer electronics industries.The suitability of the fabrication process is crucial for achieving uniform dispersion of various reinforcing materials within the Mg alloy matrix and for forming strong interfacial bonding.This ensures that the produced Mg MCs meet the requirements for fabricating various components with different demands for size and properties.This paper comprehensively reviews the present fabrication methods for MgMCs in four categories:stir casting,external addition methods,in-situ synthesis methods and novel fabrication methods.It comprehensively focuses on the fabrication principles,process characteristics and key parameters optimization of each technology.Through in-depth analysis,their advantages,limitations and applications are evaluated.Meanwhile,the latest research achievements in microstructure control and mechanical performance optimization are explored.Eventually,the development directions of the fabrication methods for MgMCs in the future are also discussed.