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Mechanical and corrosion properties of graphene nanoplatelet–reinforced Mg–Zr and Mg–Zr–Zn matrix nanocomposites for biomedical applications

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Journal of Magnesium and Alloys 2022年第2期10卷 495-514页

作者： Mohammad Shahin Cuie Wen khurram Munir Yuncang Li School of Engineering RMIT UniversityMelbourneVictoria 3001Australia

Magnesium(Mg)-based biomaterials have gained acceptability in fracture fixation due to their ability to naturally degrade in the body after fulfilling the desired ***,pure Mg not only degrades rapidly in the physiological environment,but also evolves hydrogen gas during *** this study,Mg0.5Zr and Mg0.5ZrxZn(x=1–5 wt.%)matrix nanocomposites(MNCs)reinforced with different contents(0.1–0.5 wt.%)of graphene nanoplatelets(GNP)were manufactured via a powder metallurgy technique and their mechanical and corrosion properties were *** increase in GNP concentration from 0.2 wt.%to 0.5 wt.%added to Mg0.5Zr matrices resulted in decreases in the compressive yield strength and corrosion resistance in Hanks’Balanced Salt Solution(HBSS).On the other hand,a higher concentration(4–5 wt.%)of Zn added to Mg0.5Zr0.1GNP resulted in an increase in ductility but a decrease in compressive yield ***,an addition of 0.1 wt.%GNPs to Mg0.5Zr3Zn matrices gave excellent ultimate compressive strength(387 MPa)and compressive yield strength(219 MPa).Mg0.5Zr1Zn0.1GNP and Mg0.5Zr3Zn0.1GNP nanocomposites exhibited 29%and 34%higher experimental yield strength,respectively,as compared to the theoretical yield strength of Mg0.5Zr0.1GNP calculated by synergistic strengthening mechanisms including the difference in thermal expansion,elastic modulus,and geometry of the particles,grain refinement,load transfer,and precipitation of GNPs in the Mg *** corrosion rates of Mg0.5Zr1Zn0.1GNP,Mg0.5Zr3Zn0.1GNP,Mg0.5Zr4Zn0.1GNP,and Mg0.5Zr5Zn0.1GNP measured using potentiodynamic polarization were 7.5 mm/y,4.1 mm/y,6.1 mm/y,and 8.0 mm/y,***,hydrogen gas evolution tests also demonstrated that Mg0.5Zr3Zn0.1GNP exhibited a lower corrosion rate(1.5 mm/y)than those of Mg0.5Zr1Zn0.1GNP(3.8 mm/y),Mg0.5Zr4Zn0.1GNP(1.9 mm/y),and Mg0.5Zr5Zn0.1GNP(2.2 mm/y).This study demonstrates the potential of GNPs as effective nano-reinforcement particulates for improv

关键词： Biodegradation Graphene nanoplatelet Magnesium metal matrix composite Mg–Zr–Zn alloy Strengthening mechanism

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Graphene nanoplatelets-reinforced magnesium metal matrix nanocomposites with superior mechanical and corrosion performance for biomedical applications

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Journal of Magnesium and Alloys 2020年第1期8卷 269-290页

作者： khurram Munir Cuie Wen Yuncang Li School of Engineering RMIT UniversityMelbourneVictoria 3001Australia

Magnesium(Mg)metal matrix composites(MMCs)reinforced with graphene nanoplatelets(GNPs)have been developed by powder metallurgy(PM).GNPs with different concentrations(0.1,0.2,and 0.3 wt.%),layer thicknesses(5 nm and 9 nm),and particle sizes(15μm and 5μm)were dispersed into Mg powder by high-energy ball-milling *** microstructure and mechanical properties of the fabricated composites were characterized using transmission electron microscopy(TEM),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDX),X-ray diffraction(XRD),Raman spectroscopy(RS),and compression *** corrosion resistance was evaluated by electrochemical tests and hydrogen evolution *** cytotoxicity of Mg-GNPs composites was assessed using osteoblast-like SaOS2 *** results indicate that GNPs are excellent candidates as reinforcements in Mg matrices for the manufacture of biodegradable Mg-based composite *** addition improved the mechanical properties of Mg via synergetic strengthening ***,retaining the structural integrity of GNPs during processing improved the ductility,compressive strength,and corrosion resistance of the Mg-GNP *** assessments did not reveal any significant toxicity with the addition of GNPs to Mg *** study demonstrates that Mg-xGNPs with x<0.3 wt.%,may constitute novel biodegradable implant materials for load-bearing applications.

关键词： In vitro cytotoxicity Biocorrosion Magnesium-graphene composite Mechanical properties Strengthening mechanisms

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Treatment of portal hypertension

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World Journal of Gastroenterology 2012年第11期18卷 1166-1175页

作者： khurram Bari Guadalupe Garcia-Tsao Section of Digestive Diseases Yale University School of MedicineNew HavenCT and VA-Connecticut Healthcare SystemWest HavenCT 06520United States

Portal hypertension is the main complication of cirrhosis and is defined as an hepatic venous pressure gradient （HVPG） of more than 5 mmHg. Clinically significant portal hypertension is defined as HVPG of 10 mmHg or more. Development of gastroesophageal varices and variceal hemorrhage are the most direct consequence of portal hypertension. Over the last decades significant advancements in the field have led to standard treatment options. These clinical recommendations have evolved mostly as a result of *** controlled trials and consensus conferences among experts where existing evidence has been reviewed and future goals for research and practice guidelines have been pro- posed. Management of varices/variceal hemorrhage is based on the clinical stage of portal hypertension. No specific treatment has shown to prevent the formation of varices. Prevention of first variceal hemorrhage depends on the size/characteristics of varices. In patients with small varices and high risk of bleeding, nonselective β-blockers are recommended, while patients with medium/large varices can be treated with either β-blockers or esophageal band ligation. Standard ofcare for acute variceal hemorrhage consists of vasoacrive drugs, endoscopic band ligation and antibiotics prophylaxis. Transjugular intrahepatic portosystemic shunt （TIPS） is reserved for those who fail standard of care or for patients who are likely to fail （＂early TIPS＂）. Prevention of recurrent variceal hemorrhage consists of the combination of β-blockers and endoscopic band ligation.

关键词： Cirrhosis Portal hypertension Varices Varicealhemorrhage Primary prophylaxis Secondary prophylaxis

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Improved Channel Reciprocity for Secure Communication in Next Generation Wireless Systems

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Computers, Materials & Continua 2021年第5期67卷 2619-2630页

作者： Imtisal Qadeer Muhammad khurram Ehsan Faculty of Engineering Bahria UniversityLahore CampusLahorePakistan

To secure the wireless connection between devices with low computational power has been a challenging problem due to heterogeneity in operating devices,device to device communication in Internet of Things(IoTs)and 5G wireless *** layer key generation(PLKG)tackles this secrecy problem by introducing private keys among two connecting devices through wireless *** this paper,relative calibration is used as a method to enhance channel reciprocity which in turn increases the performance of the key generation *** reciprocity based key generation is emerged as better PLKG methodology to obtain secure wireless connection in IoTs and 5G *** deconvolution is proposed as a promising technique for relative calibration to ensure channel reciprocity in comparison to existing techniques Total Least Square(TLS)and Structured Total Least Square(STLS).The proposed deconvolution technique replicates the performance of the STLS by exploiting the possibility of higher information reuse and its lesser computational complexity leads to less processing time in comparison to the *** presented idea is validated by observing the relation between signalto-noise ratio(SNR)and the correlation coefficient of the corresponding channel measurements between communicating parties.

关键词： Channel measurements physical layer key generation channel reciprocity Internet of things deconvolution

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Nano-tribological behavior of graphene nanoplatelet-reinforced magnesium matrix nanocomposites

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Journal of Magnesium and Alloys 2021年第3期9卷 895-909页

作者： Mohammad Shahin khurram Munir Cuie Wen Yuncang Li School of Engineering RMIT UniversityMelbourneVIC 3001Australia

The corrosion resistance and wear resistance of metallic biomaterials are critically important for orthopedic hard-tissue replacement applications because the lack of such properties not only adversely affects their mechanical integrity but also allows the release of wear debris into the human *** this study,the potential of zirconium(Zr)as an alloying element and graphene nanoplatelets(GNPs)as a nano-reinforcement material were investigated in relation to improving the tribological performance of pure magnesium(Mg).The GNPs-reinforced Mg matrix nanocomposites(MNCs)were fabricated using powder *** indicate that additions of 0.5 wt.%Zr and0.1 wt.%GNPs to Mg matrices significantly improved the wear resistance by 89%and 92%at 200μN load,60%and 80%at 100μN load,and 94%and 93%at 50μN load,respectively,as compared to the wear resistance of pure *** wear depth and coefficient of friction of the MNC containing 0.5 wt.%Zr and 0.1 wt.%GNPs(Mg0.5 Zr0.1 GNPs MNC)were considerably reduced as compared to pure Mg and Mg0.5 *** results demonstrate that the Mg0.5 Zr0.1 GNPs MNC is promising for orthopedic applications in relation to its excellent tribological performance.

关键词： Coefficient of friction Graphene nanoplatelet Magnesium matrix nanocomposite Wear

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Texture-based latent space disentanglement for enhancement of a training dataset for ANN-based classification of fruit and vegetables

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Information Processing in Agriculture 2023年第1期10卷 85-105页

作者： khurram Hameed Douglas Chai Alexander Rassau School of Engineering Edith Cowan University270 Joondalup DriveJoondalup WA 6027PerthAustralia

The capability of Convolutional Neural Networks(CNNs)for sparse representation has significant application to complex tasks like Representation Learning(RL).However,labelled datasets of sufficient size for learning this representation are not easily *** unsupervised learning capability of Variational Autoencoders(VAEs)and Generative Adversarial Networks(GANs)provide a promising solution to this issue through their capacity to learn representations for novel data samples and classification *** this research,a texture-based latent space disentanglement technique is proposed to enhance learning of representations for novel data samples.A comparison is performed among different VAEs and GANs with the proposed approach for synthesis of new data *** different VAE architectures are considered,a single layer dense VAE and a convolution based VAE,to compare the effectiveness of different architectures for learning of the *** GANs are selected based on the distance metric for disjoint distribution divergence estimation of complex representation learning *** proposed texture-based disentanglement has been shown to provide a significant improvement for disentangling the process of representation learning by conditioning the random noise and synthesising texture rich images of fruit and vegetables。

关键词： Information Maximisation(IM) Fruit and vegetables classification Representation Learning(RL) Variational Autoencoder(VAE) Generative Adversarial Network (GAN) Latent space disentanglement

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Multidisciplinary Design and Optimization of Multistage Ground-launched Boost Phase Interceptor Using Hybrid Search Algorithm

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Chinese Journal of Aeronautics 2010年第2期23卷 170-178页

作者： Qasim Zeeshan khurram Nisar Ali Kamran Amer Rafique School of Astronautics Beijing University of Aeronautics and Astronautics

This article proposes a multidisciplinary design and optimization （MDO） strategy for the conceptual design of a multistage ground-based interceptor （GBI） using hybrid optimization algorithm, which associates genetic algorithm （GA） as a global optimizer with sequential quadratic programming （SQP） as a local optimizer. The interceptor is comprised of a three-stage solid propulsion system for an exoatmospheric boost phase intercept （BPI）. The interceptor＇s duty is to deliver a kinetic kill vehicle （KKV） to the optimal position in space to accomplish the mission of intercept. The modules for propulsion, aerodynamics, mass properties and flight dynamics are integrated to produce a high fidelity model of the entire vehicle. The propulsion module com- prises of solid rocket motor （SRM） grain design, nozzle geometry design and performance prediction analysis. Internal ballistics and performance prediction parameters are calculated by using lumped parameter method. The design objective is to minimize the gross lift off mass （GLOM） of the interceptor under the mission constraints and performance objectives. The proposed design and optimization methodology provide designers with an efficient and powerful approach in computation during designing interceptor systems.

关键词： boost phase genetic algorithm grain design interceptor optimization solid rocket motor

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Assessment of seismic hazard of roller compacted concrete dam site in Gilgit-Baltistan of northern Pakistan

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Earthquake Engineering and Engineering Vibration 2021年第3期20卷 621-630页

作者： Shahzada khurram Perveiz Khalid Jahanzeb Qureshi Zia Ud Din Institute of Geology University of the PunjabLahore 54590Pakistan Department of Space Science University of the PunjabLahore 54590Pakistan

The proposed site of the Diamer Bhasha Dam in northern Pakistan is situated in an active tectonic zone with intensive seismicity,which makes it necessary for seismic hazard analysis(SHA).Deterministic and probabilistic approaches have been used for SHA of the dam *** Main Mantle Thrust(MMT),Main Karakaram Thrust(MKT),Raikot-Sassi Fault(RKSF)and Kohistan Fault(KF)have been considered as major seismic sources,all of which can create maximum ground shaking with maximum potential earthquake(MPE).Deterministically estimated MPE for magnitudes of 7.8,7.7,7.6,and 7.1 can be produced from MMT,MKT,RKSF and KF,*** corresponding peak ground accelerations(PGA)of 0.07,0.11,0.13 and 0.05 g can also be generated from these earthquakes,*** deterministic analysis predicts a so-called floating earthquake as a MPE of magnitude=7.1 as close as 10 km away from the *** corresponding PGA was computed as 0.38 g for a maximum design earthquake at the project ***,the probabilistic analysis revealed that the PGA with 50%probability of exceedance in 100 years is 0.18 ***,this PGA value related to the operational basis earthquake(OBE)is suggested for the design of this project with shear wave velocity(V_(s30))equal to 760 m/s under dense soil and soft rock conditions.

关键词： seismic hazard analysis peak ground acceleration Gilgat-Biltastan Diamer Bhasha Dam

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Effect of rare earth and transition metal La-Mn substitution on electrical properties of co-precipitated M-type Ba-ferrites nanoparticles

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Journal of Rare Earths 2019年第2期37卷 193-197页

作者： Muhammad Ayub Iftikhar Hussain Gul Khalid Nawaz khurram Yaqoob Thermal Transport Laboratory School of Chemical and Materials Engineering (SCME) National University of Sciences and Technology (NUST)

In the current research work Ba_(1-x)La)xMn)yFe_(12-y)O_(19) hexa-ferrite nanoparticles of different compositions were synthesized using chemical co-precipitation technique. The structural properties were explored using X-ray diffractions(XRD), scanning electron microscopy(SEM) and Fourier transmission infrared spectroscopy(FTIR). XRD indexed pattern confirms the formation of M-type hexagonal phase. The crystallite size of synthesized samples ranges from 13 to 34 ± 2 nm. FTIR peaks observe also confirmed the presence of metaloxygen bond of the desired product. The position of peak at 467 cm^(-1) corresponds to A_2 u vibration for octahedral Fe(4+)-O and peak position E1 u corresponds to vibration of Fe(3+)O4 octahedral bonds. The band v_1 in range(677-559 cm^(-1)) and v_2 in frequency range(356-419 cm^(-1)) are associated to A and B *** properties of all compositions were measured with frequency. The dielectric constant, loss and tangent loss decrease from 26 to 9, 25 to 2 and 0.94 to 0.14, respectively with frequency. DC electrical resistivity is increased with dopant concentration increasing from 2.15 × 10~4 to 1.92 ×10~5 Ω·cm.

关键词： Co-precipitation Electrical properties Dielectric X-ray diffraction Rare earths

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Coverless Steganography for Digital Images Based on a Generative Model

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Computers, Materials & Continua 2018年第6期55卷 483-493页

作者： Xintao Duan Haoxian Song Chuan Qin Muhammad khurram Khan Henan Normal University XinxiangHenan 453007China University of Shanghai for Science and Technology Shanghai 200093China Center of Excellence in Information Assurance(CoEIA) King Saud UniversityRiyadhSaudi Arabia

In this paper,we propose a novel coverless image steganographic scheme based on a generative *** our scheme,the secret image is first fed to the generative model database,to generate a meaning-normal and independent image different from the secret *** generated image is then transmitted to the receiver and fed to the generative model database to generate another image visually the same as the secret ***,we only need to transmit the meaning-normal image which is not related to the secret image,and we can achieve the same effect as the transmission of the secret *** is the first time to propose the coverless image information steganographic scheme based on generative model,compared with the traditional image *** transmitted image is not embedded with any information of the secret image in this method,therefore,can effectively resist steganalysis *** results show that our scheme has high capacity,security and reliability.

关键词： Generative model coverless image steganography steganalysis steganographic capacity security.

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