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Geometric variable designs of cam/post mechanisms influence the kinematics of knee implants

Fallahiarezoodar A, Abdul Kadir MR, Alizadeh M, Naveen SV, Kamarul T

Knee Surg Sports Traumatol Arthrosc, 2014 Dec;22(12):3019-27.
PMID: 25149643 DOI: 10.1007/s00167-014-3227-7

PURPOSE: Reproducing the femoral rollback through specially designed mechanism in knee implants is required to achieve full knee function in total knee arthroplasty. Most contemporary implants use cam/post mechanism to replace the function of Posterior Cruciate Ligament. This study was aimed to determine the most appropriate cam and post designs to produce normal femoral rollback of the knee.
METHODS: Three different cams (triangle, ellipse, and circle) and three different posts (straight, convex, concave) geometries were considered in this study and were analysed using kinematic analyses. Femoral rollback did not occur until reaching 50° of knee flexion. Beyond this angle, two of the nine combinations demonstrate poor knee flexion and were eliminated from the study.
RESULTS: The combination of circle cam with concave post, straight post and convex post showed 15.6, 15.9 and 16.1 mm posterior translation of the femur, respectively. The use of ellipse cam with convex post and straight post demonstrated a 15.3 and 14.9 mm femoral rollback, whilst the combination of triangle cam with convex post and straight post showed 16.1 and 15.8 mm femoral rollback, respectively.
CONCLUSION: The present study demonstrates that the use of circle cam and convex post created the best femoral rollback effect which in turn produces the highest amount of knee flexion. The findings of the study suggest that if the design is applied for knee implants, superior knee flexion may be possible for future patients.
LEVEL OF EVIDENCE: IV.
Fulltext Trusted computing strengthens cloud authentication

Ghazizadeh E, Zamani M, Ab Manan JL, Alizadeh M

ScientificWorldJournal, 2014;2014:260187.
PMID: 24701149 DOI: 10.1155/2014/260187

Cloud computing is a new generation of technology which is designed to provide the commercial necessities, solve the IT management issues, and run the appropriate applications. Another entry on the list of cloud functions which has been handled internally is Identity Access Management (IAM). Companies encounter IAM as security challenges while adopting more technologies became apparent. Trust Multi-tenancy and trusted computing based on a Trusted Platform Module (TPM) are great technologies for solving the trust and security concerns in the cloud identity environment. Single sign-on (SSO) and OpenID have been released to solve security and privacy problems for cloud identity. This paper proposes the use of trusted computing, Federated Identity Management, and OpenID Web SSO to solve identity theft in the cloud. Besides, this proposed model has been simulated in .Net environment. Security analyzing, simulation, and BLP confidential model are three ways to evaluate and analyze our proposed model.
Fulltext The use of X-shaped cross-link in posterior spinal constructs improves stability in thoracolumbar burst fracture: a finite element analysis

Alizadeh M, Kadir MR, Fadhli MM, Fallahiarezoodar A, Azmi B, Murali MR, et al.

J Orthop Res, 2013 Sep;31(9):1447-54.
PMID: 23640802 DOI: 10.1002/jor.22376

Posterior instrumentation is a common fixation method used to treat thoracolumbar burst fractures. However, the role of different cross-link configurations in improving fixation stability in these fractures has not been established. A 3D finite element model of T11-L3 was used to investigate the biomechanical behavior of short (2 level) and long (4 level) segmental spine pedicle screw fixation with various cross-links to treat a hypothetical L1 vertebra burst fracture. Three types of cross-link configurations with an applied moment of 7.5 Nm and 200 N axial force were evaluated. The long construct was stiffer than the short construct irrespective of whether the cross-links were used (p < 0.05). The short constructs showed no significant differences between the cross-link configurations. The XL cross-link provided the highest stiffness and was 14.9% stiffer than the one without a cross-link. The long construct resulted in reduced stress to the adjacent vertebral bodies and screw necks, with 66.7% reduction in bending stress on L2 when the XL cross-link was used. Thus, the stability for L1 burst fracture fixation was best achieved by using long segmental posterior instrumentation constructs and an XL cross-link configuration. Cross-links did not improved stability when a short structure was used.
A cobalt oxide nanocubes interleaved reduced graphene oxide nanocomposite modified glassy carbon electrode for amperometric detection of serotonin

Shahid MM, Rameshkumar P, Numan A, Shahabuddin S, Alizadeh M, Khiew PS, et al.

Mater Sci Eng C Mater Biol Appl, 2019 Jul;100:388-395.
PMID: 30948075 DOI: 10.1016/j.msec.2019.02.107

Cobalt oxide nanocubes incorporated with reduced graphene oxide (rGO-Co3O4) was prepared by using simple one-step hydrothermal route. Crystallinity and structural characteristics of the nanocomposite were analyzed and confirmed using X-ray diffraction (XRD) and Raman analysis, respectively. The cubical shape of the Co3O4 nanostructures and the distribution of Co3O4 nanocubes on the surface of rGO sheets were identified through field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) mapping analysis, respectively. Raman spectra depicted the presence of D and G bands for GO and rGO with different ID/IG values and thus confirmed the reduction of GO into rGO. The electrochemical study reflects that the rGO-Co3O4 nanocomposite shows good electrocatalytic activity in oxidation of depression biomarker serotonin (5-HT) in phosphate buffer (pH 7.2). The detection of 5-HT was carried out by using rGO-Co3O4 nanocomposite modified glassy carbon electrode under dynamic condition using amperometry technique with a linear range of 1-10 μM. The limit of detection and limit of quantification were calculated and found to be 1.128 and 3.760 μM, respectively with a sensitivity value of 0.133 μΑ·μM-1. The sensor showed selectivity in the presence of different interferent species such as ascorbic acid, dopamine and uric acid.
Fulltext Solid-State Limited Nucleation of NiSi/SiC Core-Shell Nanowires by Hot-Wire Chemical Vapor Deposition

Alizadeh M, Binti Hamzan N, Ooi PC, Bin Omar MF, Dee CF, Goh BT

Materials (Basel), 2019 Feb 24;12(4).
PMID: 30813502 DOI: 10.3390/ma12040674

This work demonstrated a growth of well-aligned NiSi/SiC core-shell nanowires by a one-step process of hot-wire chemical vapor deposition on Ni-coated crystal silicon substrates at different thicknesses. The NiSi nanoparticles (60 to 207 nm) acted as nano-templates to initially inducing the growth of these core-shell nanowires. These core-shell nanowires were structured by single crystalline NiSi and amorphous SiC as the cores and shells of the nanowires, respectively. It is proposed that the precipitation of the NiSi/SiC are followed according to the nucleation limited silicide reaction and the surface-migration respectively for these core-shell nanowires. The electrical performance of the grown NiSi/SiC core-shell nanowires was characterized by the conducting AFM and it is found that the measured conductivities of the nanowires were higher than the reported works that might be enhanced by SiC shell layer on NiSi nanowires. The high conductivity of NiSi/SiC core-shell nanowires could potentially improve the electrical performance of the nanowires-based devices for harsh environment applications such as field effect transistors, field emitters, space sensors, and electrochemical devices.
Fulltext IoMT amid COVID-19 pandemic: Application, architecture, technology, and security

Mohd Aman AH, Hassan WH, Sameen S, Attarbashi ZS, Alizadeh M, Latiff LA

J Netw Comput Appl, 2021 Jan 15;174:102886.
PMID: 34173428 DOI: 10.1016/j.jnca.2020.102886

In many countries, the Internet of Medical Things (IoMT) has been deployed in tandem with other strategies to curb the spread of COVID-19, improve the safety of front-line personnel, increase efficacy by lessening the severity of the disease on human lives, and decrease mortality rates. Significant inroads have been achieved in terms of applications and technology, as well as security which have also been magnified through the rapid and widespread adoption of IoMT across the globe. A number of on-going researches show the adoption of secure IoMT applications is possible by incorporating security measures with the technology. Furthermore, the development of new IoMT technologies merge with Artificial Intelligence, Big Data and Blockchain offers more viable solutions. Hence, this paper highlights the IoMT architecture, applications, technologies, and security developments that have been made with respect to IoMT in combating COVID-19. Additionally, this paper provides useful insights into specific IoMT architecture models, emerging IoMT applications, IoMT security measurements, and technology direction that apply to many IoMT systems within the medical environment to combat COVID-19.
Fulltext Cryptanalysis and Improvement of "A Secure Password Authentication Mechanism for Seamless Handover in Proxy Mobile IPv6 Networks"

Alizadeh M, Zamani M, Baharun S, Abdul Manaf A, Sakurai K, Anada H, et al.

PLoS One, 2015;10(11):e0142716.
PMID: 26580963 DOI: 10.1371/journal.pone.0142716

Proxy Mobile IPv6 is a network-based localized mobility management protocol that supports mobility without mobile nodes' participation in mobility signaling. The details of user authentication procedure are not specified in this standard, hence, many authentication schemes have been proposed for this standard. In 2013, Chuang et al., proposed an authentication method for PMIPv6, called SPAM. However, Chuang et al.'s Scheme protects the network against some security attacks, but it is still vulnerable to impersonation and password guessing attacks. In addition, we discuss other security drawbacks such as lack of revocation procedure in case of loss or stolen device, and anonymity issues of the Chuang et al.'s scheme. We further propose an enhanced authentication method to mitigate the security issues of SPAM method and evaluate our scheme using BAN logic.