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A thermostabilized magnetogenosensing assay for DNA sequence-specific detection and quantification of Vibrio cholerae

Low KF, Karimah A, Yean CY

Biosens Bioelectron, 2013 Sep 15;47:38-44.
PMID: 23545172 DOI: 10.1016/j.bios.2013.03.004

Vibrio cholerae is a human pathogen that causes mild to severe diarrheal illnesses and has major public health significance. Herein, we present a thermostabilized electrochemical genosensing assay combining the use of magnetic beads as a biorecognition platform and gold nanoparticles as a hybridization tag for the detection and quantification of V. cholerae lolB gene single-stranded asymmetric PCR amplicons as an alternative to the time-consuming classical isolation method. This thermostabilized, pre-mixed, pre-aliquoted and ready-to-use magnetogenosensing assay simplified the procedures and permitted the reaction to be conducted at room temperature. The asymmetric PCR amplicons were hybridized to a magnetic bead-functionalized capture probe and a fluorescein-labeled detection probe followed by tagging with gold nanoparticles. Electrochemical detection of the chemically dissolved gold nanoparticles was performed using the differential pulse anodic stripping voltammetry method. The real-time stability evaluation of thermostabilized assay was found to be stable for at least 180 days at room temperature (25-30°C). The analytical specificity of the assay was 100%, while its analytical sensitivity was linearly related to different concentrations of 200-mer synthetic target, purified genomic DNA, and bacterial culture with a limit of detection (LoD) of 3.9nM, 5pg/µl, and 10(3)CFU/ml, respectively. The clinical applicability of the assay was successfully validated using spiked stool samples with an average current signal-to-cut-off ratio of 10.8. Overall, the precision of the assay via relative standard deviation was <10%, demonstrating its reliability and accuracy.

Matched MeSH terms: Magnets
Fulltext Enhanced Recyclable Magnetized Palm Shell Waste-Based Powdered Activated Carbon for the Removal of Ibuprofen: Insights for Kinetics and Mechanisms

Wong KT, Yoon Y, Jang M

PLoS One, 2015;10(10):e0141013.
PMID: 26496196 DOI: 10.1371/journal.pone.0141013

A novel preparation method of magnetized palm shell waste-based powdered activated carbon (MPPAC, avg. size 112 μm) was developed. The prepared MPPAC was assessed by several physicochemical analyses, and batch tests were performed for ibuprofen (IBP) removal. Field emission scanning electron microscopy (FESEM) and N2 gas isotherms revealed that magnetite and maghemite were homogeneous and deposited mostly on the surface of PPAC without a significant clogging effect on the micropores. Isotherm results showed that 3.8% Fe (w/w) impregnated PPAC [MPPAC-Fe(3.8%)] had about 2.2-fold higher maximum sorption capacity (157.3 mg g-1) and a 2.5-fold higher sorption density (0.23 mg m-2) than pristine PPAC. Both Fourier-transform infrared spectroscopy (FTIR) and isotherm data indicated that the high sorption capacity and density of IBP by MPPAC was primarily attributable to donor-acceptor complexes with the C = O group and dispersive π-π interactions with the carbon surface. Based on kinetic and repeated adsorption tests, pore diffusion was the rate-limiting step, and MPPAC-Fe(3.8%) had about 1.9~2.8- and 9.1~15.8-fold higher rate constants than MPPAC-Fe(8.6%) and palm shell-waste granular activated carbon (PGAC, avg. size 621 μm), respectively. MPPAC showed almost eight fold greater re-adsorption capacity than PPAC due to a thermal catalytic effect of magnetite/maghemite.

Matched MeSH terms: Magnets
Rehabilitation of an extraoral and intraoral defect complicated with microstomia. A study case

Abdulhadi LM

Eur J Prosthodont Restor Dent, 2012 Jun;20(2):81-5.
PMID: 22852525

A 72-year-old man was referred from the surgery department for rehabilitation following surgical resection of Basaloid carcinoma. The first surgical intervention involved the anterior palatal region and was restored with a simple obturator. Two years later further surgery was undertaken to excise a recurrent tumor in the nose and part of the cheek. This resulted in an exposed nasal cavity and maxillary sinus. In addition, there was a small oral aperture composed of thin tissue that stretched to its maximum due to scar formation. The defect was restored with a full thickness skin flap but it subsequently broke down leaving the midface exposed with limited mouth opening due to tissue contraction and scar formation after the flap operation. The defect was rehabilitated with Co-Cr obturator intraorally and a silicone nose retained to the naso-palatal extension of the obturator by a magnet extraorally. This resulted in practically good retention, placement, and adaptation of the two parts of the prosthesis.

Matched MeSH terms: Magnets*
Fulltext Electromagnetic Characterization of a Multiwalled Carbon Nanotubes-Silver Nanoparticles-Reinforced Polyvinyl Alcohol Hybrid Nanocomposite in X-Band Frequency

Yusof Y, Moosavi S, Johan MR, Badruddin IA, Wahab YA, Hamizi NA, et al.

ACS Omega, 2021 Feb 16;6(6):4184-4191.
PMID: 33644542 DOI: 10.1021/acsomega.0c04864

This study presents the electromagnetic (EM) characterization of a multiwalled carbon nanotubes (MWCNT)-silver nanoparticles (AgNP)-reinforced poly(vinyl alcohol) (PVA) hybrid nanocomposite fabricated via the solution mixing technique. Primarily, the structure and morphological properties of the PVA/MWCNT-AgNP hybrid nanocomposite are confirmed by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The complex permittivity (ε*) and permeability (μ*), as well as the electromagnetic scattering parameters are measured using a PNA network analyzer equipped with X-band waveguide. The results showed an enhanced permittivity (ε' ≈ 25) value of the hybrid nanocomposite in the frequency range of 8-12 GHz. However, the permeability decreased to almost zero (μ' ≈ 0.4) since the inclusion of AgNP with an average particle size of 40 nm is not susceptible to magnetization and causes higher magnetic losses (tan δμ) than dielectric losses (tan δε). Remarkably, the hybrid nanocomposite reduced transmission of electromagnetic (EM) wave by nearly 60% in comparison to PVA/MWCNT. This is attributed to the enhanced absorption and reflection at the nanotubes, and metal-dielectric interfaces have induced multiple internal reflections owing to the porous structure of the nanocomposite. The prospect of the PVA/MWCNT-AgNP hybrid nanocomposite is favorable as a thin absorbing material for EM shielding applications.

Matched MeSH terms: Magnets
Surface engineered iron oxide nanoparticles as efficient materials for antibiofilm application

Velusamy P, Su CH, Kannan K, Kumar GV, Anbu P, Gopinath SCB

Biotechnol Appl Biochem, 2021 Mar 10.
PMID: 33751641 DOI: 10.1002/bab.2146

Overuse of antibiotics has led to the development of multi drug resistant strains. Antibiotic resistance is a major drawback in the biomedical field since medical implants are prone to infection by biofilms of antibiotic resistant strains of bacteria. With increasing prevalence of antibiotic resistant pathogenic bacteria, the search for alternative method is utmost importance. In this regard, magnetic nanoparticles are commonly used as a substitute for antibiotics that can circumvent the problem of biofilms growth on the surface of biomedical implants. Iron oxide nanoparticles (IONPs) have unique magnetic properties that can be exploited in various ways in the biomedical applications. IONPs are engineered employing different methods to induce surface functionalization that include the use of polyethyleneimine and oleic acid. IONPs have a mechanical effect on biofilms when in presence of an external magnet. In this review, a detailed description of surface engineered magnetic nanoparticles as ideal antibacterial agents is provided, accompanied by various methods of literature review. This article is protected by copyright. All rights reserved.

Matched MeSH terms: Magnets
Fulltext Simultaneous Co(II)-Titanium(IV) substitution in magnetoplumbite-type barium ferrite nanoparticles

Teh, G.B., Wong, Y.C., Tilley, R.D.

ASM Science Journal, 2014;8(1):21-28.
MyJurnal

Co(II)-Ti(IV)-substituted magnetoplumbite-type (M-type) barium ferrite nanoparticles were synthesized via the sol-gel technique employing ethylene glycol as the gel precursor. Structural and magnetic properties were characterised via X-ray diffraction (XRD), high resolution transmission electron microscopy and superconducting quantum interference device magnetometry. The particle sizes of the M-type BaCoXTiXFe12-2XO19 (0.2 ≤  ≤ 1.0) were found to be 900 Å – 1500 Å. The XRD results confirmed that the Co(II)-Ti(IV) substituted ferrites in the range of 0.2 ≤  ≤ 1.0 substitution had the M-type ferrite as the dominant phase. The hysteresis loss per-cycle decreased with increasing Co(II)-Ti(IV) substitution in M-type ferrites which showed reduced values in coercivity and remnant magnetisation with moderate effect on the saturation magnetisation.

Matched MeSH terms: Magnets
Effects of Yttria Doping on Some Properties of YBa2Cu3O7-Î´ Superconductor

Mustaffa Hj. Abdullah, Tan TK

Sains Malaysiana, 1997;26.

Samples of Y-Ba-Cu-O superconductor with nominal compositions of YBa2Cu3O7-d + x (weight %) Y2O3 (x = 0 - 15) were prepared by solid state reaction method using the Y2Cu2O5 and BaCuO2 precursors as the starting reagents. The X-ray diffraction (XRD) diffractograms for the doped samples (x> 0) show an additional non-superconducting Y2BaCuO5 (211) phase. The scanning electron microscope (SEM) micrographs show that the smaller Y2BaCuO5 grains are precipitated on the surface of the larger YBa2Cu3O7-d (YBCO) crystals. The grain size of the YBCO decreases with increasing yttria. The superconducting zero resistivity critical temperature (Tco) of the doped samples is very close to the Tco of the YBCO for x < 5, but it seems to be significantly decreasing for larger x. The transport critical current density (J) for x < 5 is enhanced due to magnetic flux pinning process by the 211 phase. However, Jc decreased for larger x due to the increase of weak links at the grain boundaries of the YBCO phase.
Sampel superkonduktor Y-Ba-Cu-O dengan komposisi nominal YBa2Cu3O7-d + x (% berat) Y2O3 (x = 0 -15) disediakan dengan kaedah tindakbalas keadaan pepejal menggunakan bahan pelopor Y2Cu2O5 dan BaCuO2 Difraktogram pembelauan sinar-X (XRD) bagi sampel yang didop (x > 0) menunjukkan wujudnya fasa tak mensuperkonduksi Y2BaCuO5 (211). Mikrograf mikroskop imbasan elektron (SEM) menunjukkan bahawa butiran Y2BaCuO5 yang lebih kecil itu termendap di atas permukaan hablur YBa2Cu3O7-d yang lebih besar. Saiz hablur YBCO mengecil dengan peningkatan yittria. Suhu genting kerintangan sifar (Tc) bagi sampel yang didop adalah hampir dengan Tco bagi YBCO untuk x<5, tetapi menurun dengan agak cepat untuk x yang lebih besar. Ketumpatan arus genting angkutan (J) untuk x < 5 meningkat jika dibandingkan dengan YBCO disebabkan oleh proses kepinan fluks magnet oleh fasa 211. Walau bagaimanapun, Jc menurun untuk x yang lebih tinggi kerana meningkatnya hubungan lemah pada sempadan butiran fasa YBCO.

Matched MeSH terms: Magnets
Prosthetic management of mid-facial defect with magnet-retained silicone prosthesis

Buzayan MM

Prosthet Orthot Int, 2014 Feb;38(1):62-7.
PMID: 23625838 DOI: 10.1177/0309364613484052

Mid-facial defect is one of the most disfiguring and impairing defects. A design of prosthesis that is aesthetic and stable can be precious to a patient who has lost part of his face due to surgical excision. Prosthesis can restore the patients' self-esteem and confidence, which affects the patients and their life style. The aim of this case report is to describe a technique of mid-facial silicone prosthesis fabrication.

Matched MeSH terms: Magnets*
Fulltext Facile aerobic construction of iron based ferromagnetic nanostructures by a novel microbial nanofactory isolated from tropical freshwater wetlands

Jacob PJ, Masarudin MJ, Hussein MZ, Rahim RA

Microb Cell Fact, 2017 Oct 11;16(1):175.
PMID: 29020992 DOI: 10.1186/s12934-017-0789-3

BACKGROUND: Iron based ferromagnetic nanoparticles (IONP) have found a wide range of application in microelectronics, chemotherapeutic cell targeting, and as contrast enhancers in MRI. As such, the design of well-defined monodisperse IONPs is crucial to ensure effectiveness in these applications. Although these nanostructures are currently manufactured using chemical and physical processes, these methods are not environmentally conducive and weigh heavily on energy and outlays. Certain microorganisms have the innate ability to reduce metallic ions in aqueous solution and generate nano-sized IONP's with narrow size distribution. Harnessing this potential is a way forward in constructing microbial nanofactories, capable of churning out high yields of well-defined IONP's with physico-chemical characteristics on par with the synthetically produced ones.
RESULTS: In this work, we report the molecular characterization of an actinomycetes, isolated from tropical freshwater wetlands sediments, that demonstrated rapid aerobic extracellular reduction of ferric ions to generate iron based nanoparticles. Characterization of these nanoparticles was carried out using Field Emission Scanning Electron Microscope with energy dispersive X-ray spectroscopy (FESEM-EDX), Field Emission Transmission Electron Microscope (FETEM), Ultraviolet-Visible (UV-Vis) Spectrophotometer, dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR). This process was carried out at room temperature and humidity and under aerobic conditions and could be developed as an environmental friendly, cost effective bioprocess for the production of IONP's.
CONCLUSION: While it is undeniable that iron reducing microorganisms confer a largely untapped resource as potent nanofactories, these bioprocesses are largely anaerobic and hampered by the low reaction rates, highly stringent microbial cultural conditions and polydispersed nanostructures. In this work, the novel isolate demonstrated rapid, aerobic reduction of ferric ions in its extracellular matrix, resulting in IONPs of relatively narrow size distribution which are easily extracted and purified without the need for convoluted procedures. It is therefore hoped that this isolate could be potentially developed as an effective nanofactory in the future.

Matched MeSH terms: Magnets/chemistry*
Development of magnetic porous coordination polymer adsorbent for the removal and preconcentration of Pb(II) from environmental water samples

Al'Abri AM, Mohamad S, Abdul Halim SN, Abu Bakar NK

Environ Sci Pollut Res Int, 2019 Apr;26(11):11410-11426.
PMID: 30805837 DOI: 10.1007/s11356-019-04467-w

A novel porous coordination polymer adsorbent (BTCA-P-Cu-CP) based on a piperazine(P) as a ligand and 1,2,4,5-benzenetetracarboxylic acid (BTCA) as a linker was synthesized and magnetized to form magnetic porous coordination polymer (BTCA-P-Cu-MCP). Fourier transform infrared (FTIR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), field emission scanning electron microscope(FESEM), energy-dispersive X-ray spectroscopy(EDS), CHN, and Brunauer-Emmett-Teller(BET) analysis were used to characterize the synthesized adsorbent. BTCA-P-Cu-MCP was used for removal and preconcentration of Pb(II) ions from environmental water samples prior to flame atomic absorption spectrometry(FAAS) analysis. The maximum adsorption capacity of BTCA-P-Cu-MCP was 582 mg g-1. Adsorption isotherm, kinetic, and thermodynamic parameters were investigated for Pb(II) ions adsorption. Magnetic solid phase extraction (MSPE) method was used for preconcentration of Pb(II) ions and the parameters influencing the preconcentration process have been examined. The linearity range of proposed method was 0.1-100 μg L-1 with a preconcentration factor of 100. The limits of detection and limits of quantification for lead were 0.03 μg L-1 and 0.11 μg L-1, respectively. The intra-day (n = 7) and inter-day (n = 3) relative standard deviations (RSDs) were 1.54 and 3.43% respectively. The recoveries from 94.75 ± 4 to 100.93 ± 1.9% were obtained for rapid extraction of trace levels of Pb(II) ions in different water samples. The results showed that the BTCA-P-Cu-MCP was steady and effective adsorbent for the decontamination and preconcentration of lead ions from the aqueous environment.

Matched MeSH terms: Magnets/chemistry*
Fluoride adsorption by doped and un-doped magnetic ferrites CuCe(x)Fe(2-x)O4: Preparation, characterization, optimization and modeling for effectual remediation technologies

Rehman MA, Yusoff I, Alias Y

J Hazard Mater, 2015 Dec 15;299:316-24.
PMID: 26143194 DOI: 10.1016/j.jhazmat.2015.06.030

A series of doped and un-doped magnetic adsorbents CuCexFe2-xO4 (x=0.0-0.5) for fluoride were prepared with the micro-emulsion method. Fluoride adsorption was optimized for solution pH, temperature, contact time, and initial concentration and was monitored via normal phase ion chromatography (IC). The effect of concomitant anions was also explored to perform and simulate competitive fluoride adsorption in real water samples. Optimal adsorption was discovered by a simple quadratic model based on central composite design (CCD) and the response surface method (RSM). The adsorption, electrochemical and magnetic properties were compared between doped and un-doped ferrites. Doped ferrites (x=0.1-0.5) were found to be superior to un-doped ferrites (x=0) regarding the active sites, functional groups and fluoride adsorption. The characterization, optimization and application results of the doped ferrites indicated enhanced fluoride adsorption and easy separation with a simple magnet.

Matched MeSH terms: Magnets
Fulltext Mobile robot climber model for experiments application

Syahrul Affandi Saidi, Beh, Jun Long, Mohd Sharizan Md Sarip, Wan Azani Mustafa

Journal of Advanced Research in Applied Sciences and Engineering Technology, 2018;13(1):1-7.
MyJurnal

This article presents a Wall Climbing Robot (WCR) that able to move on ferromagnetic vertical surface to carry out visual inspection process. Visual inspection process is important in the industry to check the condition of storage tank, surface of building, piping or equipment thus can prevents structures collapsing or explosion which would bring a huge loss to the company. Moreover, most of the structures nowadays is expose under the sun and rain, corrosion and cracks could easily occur on the surface after exposing under sunlight and rain a long period of time. Therefore the periodic visual inspection process need to be carry out to detect the damaged occur on the surface of the structure and take action at the fastest time to ensure the safety of the structures and extend the lifespan of the structures. With the well maintenance to the structures, the condition of the structures is monitored and the lifespan is longer. The risk of collapse of the building is decrease by a large margin. Normally, the periodic visual inspection process is performed by operator. Sometime the temporary scaffolding is needed to reach the higher place to carry out the inspection. However, this method create a hazardous environment to the operator and cause the safety of the operator threatened. Therefore, the proposed WCR could help operator to work at the hazardous environment. The permanent magnet is used to provide adhesion for WCR, thus WCR able to move on vertical ferromagnetic surface. The WCR is controlled by operator via wireless remote to reach the higher place or the hazardous environment. The operator then can stream the on the real time images via web browser which connected to the same network with the WCR. Hence, the condition of the surface can be observed.

Matched MeSH terms: Magnets
Fulltext Process Optimization of In Situ Magnetic-Anisotropy Spark Plasma Sintering of M-Type-Based Barium Hexaferrite BaFe12O19

Mohammed HG, Albarody TMB, Susilawati S, Gohari S, Doyan A, Prayogi S, et al.

Materials (Basel), 2021 May 18;14(10).
PMID: 34070195 DOI: 10.3390/ma14102650

This paper introduces a new spark plasma sintering technique that is able to order crystalline anisotropy by in-series/in situ DC electric coupled magnetic field. The process control parameters have been investigated on the production of anisotropic BaFe12O19 magnets based on resulted remanence (Mr). Sintering holding time (H.T.), cooling rate (C.R.), pressure (P), and sintering temperature (S.T.) are optimized by Taguchi with L9 orthogonal array (OA). The remanent magnetization of nanocrystalline BaFe12O19 in parallel (Mrǁ) and perpendicular (MrꞱ) to the applied magnetic field was regarded as a measure of performance. The Taguchi study calculated optimum process parameters, which significantly improved the sintering process based on the confirmation tests of BaFe12O19 anisotropy. The magnetic properties in terms of Mrǁ and MrꞱ were greatly affected by sintering temperature and pressure according to ANOVA results. In addition, regression models were developed for predicting the Mrǁ as well as MrꞱ respectively.

Matched MeSH terms: Magnets
Fulltext Fabrication of size-tunable nanocrystalline cobalt particles in propylene glycol

Balela, M.D.L., Lockman, Z., Azizan, A., Matsubara, E., Amorsolo , A.V. Jr.

Journal of Nuclear and Related Technologies, 2009;2009(1):190-198.
MyJurnal

Monodispersed and size-tunable nanocrystalline cobalt (Co) particles in the range of 100 to 400 nm are prepared by the reduction of Co(II) species in propylene glycol. Control of the particle size is achieved by varying the initial Co(II) species concentration and by the addition of nucleating agents. Smaller Co particles are produced with increasing amounts of Co(II) species and in the presence of nucleating agents. X-ray diffraction analysis (XRD) shows that the Co particles are predominantly face-centered cubic crystals of about 8-14 nm. The Co particles are also ferromagnetic at room temperature.

Matched MeSH terms: Magnets
Fulltext Development of internet-based instrumentation for the study of hall effect

Ariffin Abas, Abdul Halim Shaari, Zainal Abidin Talib, Zaidan Abdul Wahab

Pertanika Journal of Science & Technology, 2014;22(1):105-112.
MyJurnal

The computer, together with Lab View software, can be used as an automatic data acquisition system. This project deals with the development of a computer interfacing technique for the study of Hall Effect and converting the existing automation system into a Web-based automation system. The drive board RS 217-3611 with PCI 6025E card and stepper motor RS191-8340 with a resolution of 0.1mm, was used to move a pair of permanent magnets backward and forward against the sample. The General Interface Bus (GPIB) card interfaces, together with digital nano voltmeter and Tesla meter using serial port RS232 interface, are used for measuring the potential difference and magnetic field strength respectively. Hall Effect measurement on copper (Cu) and tantalum (Ta) showed negative and positive sign Hall coefficient. Therefore, the system has electron and hole charge carriers respectively at room temperature. The parameters such as drift velocity, conductivity, mobility, Hall Coefficient and charge carrier concentration were also automatically displayed on the front panel of Lab View programming and compared with standard value. The Web-based automation system can be remotely controlled and monitored by users in remote locations using only their web browsers. In addition, video conferencing through Net Meeting has been used to provide audio and video feedback to the client.

Matched MeSH terms: Magnets
Fulltext Multiple magnet ingestion: The attractive hazardst

Othman MY, Singaravel S

Med J Malaysia, 2016 Aug;71(4):211-212.
PMID: 27770124

Foreign body ingestion among children is common and most usually pass through the gastrointestinal tract without requiring any intervention. Magnets, however, pose a greater threat especially when more than one are ingested. We report a case of multiple bowel perforation secondary to ingestion of magnetic beads in a 3-year-old.

Matched MeSH terms: Magnets
Penagihan heroin: Implikasi kepada saraf otak, ingatan serta pengaruhnya terhadap fenomena tingkah laku relaps dengan menggunakan FMRI

Chandralekah SV, Wan Shahrazad WS, Khairudin R, Syazarina SO, Mahamood Y

Jurnal Psikologi Malaysia, 2013;olume 27:55-71.

Kes relaps dalam kalangan penagih dadah heroin semakin meningkat bilangannya di Malaysia. Kajian ini cuba mengaitkan kes relaps ini dengan tempoh penyalahgunaan heroin terhadap daya ingatan dan bahagian otak dalam usaha meleraikan persoalan tingkah laku relaps. Seramai 45 orang subjek terlibat dalam kajian ini. Kesemua subjek dipilih secara rawak berdasarkan kepada tempoh penagihan. Subjek dibahagi berdasarkan tempoh penagihan singkat, penagihan lama dan subjek normal. Setiap kumpulan diwakili seramai 15 orang subjek. Kajian ini dijalankan secara eksperimen selari dengan menggunakan ujian tingkah laku melalui ujian ingatan N-Back dan juga ujian pengimejan melalui ujian (fMRI). Dapatan data daripada ujian tingkah laku dianalisis menggunakan Program SPSS. Manakala data daripada ujian kefungsian pengimejan resonans magnet (fMRI) dianalisis menggunakan perisian pemetaan statistik berparameter (SPM) dan MATLAB (r2008a). Pengujian hipotesis dilakukan dengan menggunakan ujian ANOVA rekabentuk campuran (repeated measure) dan juga Post Hoc serta analisis kesan rawak (RFX) untuk melihat tahap pengaktifan otak yang dilakukan dengan menggunakan SPM. Hasil kajian menunjukkan bahawa daya ingatan berbeza secara signifikan mengikut tempoh pengambilan, wujud interaksi yang signifikan antara tempoh pengambilan dadah dengan ujian N-Back, dan perbezaan corak pengaktifan pada bahagian otak dalam kumpulan eksperimen dan kawalan mengikut kesukaran ujian N-Back yang diberikan. Kajian ini menunjukkan semakin tinggi tempoh penagihan semakin kurang pengaktifan bahagian otak dan semakin tinggilah kecenderungan penagih untuk merelaps.

Matched MeSH terms: Magnets
Fulltext A mobile ferromagnetic shape detection sensor using a Hall sensor array and magnetic imaging

Misron N, Shin NW, Shafie S, Marhaban MH, Mailah NF

Sensors (Basel), 2011;11(11):10474-89.
PMID: 22346653 DOI: 10.3390/s111110474

This paper presents a mobile Hall sensor array system for the shape detection of ferromagnetic materials that are embedded in walls or floors. The operation of the mobile Hall sensor array system is based on the principle of magnetic flux leakage to describe the shape of the ferromagnetic material. Two permanent magnets are used to generate the magnetic flux flow. The distribution of magnetic flux is perturbed as the ferromagnetic material is brought near the permanent magnets and the changes in magnetic flux distribution are detected by the 1-D array of the Hall sensor array setup. The process for magnetic imaging of the magnetic flux distribution is done by a signal processing unit before it displays the real time images using a netbook. A signal processing application software is developed for the 1-D Hall sensor array signal acquisition and processing to construct a 2-D array matrix. The processed 1-D Hall sensor array signals are later used to construct the magnetic image of ferromagnetic material based on the voltage signal and the magnetic flux distribution. The experimental results illustrate how the shape of specimens such as square, round and triangle shapes is determined through magnetic images based on the voltage signal and magnetic flux distribution of the specimen. In addition, the magnetic images of actual ferromagnetic objects are also illustrated to prove the functionality of mobile Hall sensor array system for actual shape detection. The results prove that the mobile Hall sensor array system is able to perform magnetic imaging in identifying various ferromagnetic materials.

Matched MeSH terms: Magnets
Fulltext Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications

Rifai D, Abdalla AN, Ali K, Razali R

Sensors (Basel), 2016;16(3):298.
PMID: 26927123 DOI: 10.3390/s16030298

Non-destructive eddy current testing (ECT) is widely used to examine structural defects in ferromagnetic pipe in the oil and gas industry. Implementation of giant magnetoresistance (GMR) sensors as magnetic field sensors to detect the changes of magnetic field continuity have increased the sensitivity of eddy current techniques in detecting the material defect profile. However, not many researchers have described in detail the structure and issues of GMR sensors and their application in eddy current techniques for nondestructive testing. This paper will describe the implementation of GMR sensors in non-destructive testing eddy current testing. The first part of this paper will describe the structure and principles of GMR sensors. The second part outlines the principles and types of eddy current testing probe that have been studied and developed by previous researchers. The influence of various parameters on the GMR measurement and a factor affecting in eddy current testing will be described in detail in the third part of this paper. Finally, this paper will discuss the limitations of coil probe and compensation techniques that researchers have applied in eddy current testing probes. A comprehensive review of previous studies on the application of GMR sensors in non-destructive eddy current testing also be given at the end of this paper.

Matched MeSH terms: Magnets
Fulltext Pengaktifan otak akibat gerakan jari bagi subjek dominan tangan kanan dan kiri

Ahmad Nazlim Yusoff, Mohd Harith Hashim, Mohd Mahadir Ayob, Iskandar Kassim

Jurnal Sains Kesihatan Malaysia, 2006;4(2):63-83.
MyJurnal

Kajian garis pangkal pengimejan resonans magnet kefungsian (fMRI) telah dijalankan ke atas 2 orang subjek lelaki sihat dominan tangan kanan dan kiri. Kajian ini menggunakan gerakan jari tangan kanan dan kiri untuk merangsang aktiviti neuron di dalam korteks serebrum. Subjek diarahkan supaya menekan jari-jari pada ibu jari secara bergilir-gilir semasa imbasan fMRI dilakukan. Paradigma 5 kitar aktif-rehat digunakan dengan setiap kitar mengandungi satu blok aktif dan satu blok rehat dengan 10 siri pengukuran untuk setiap blok. Seratus isipadu imej fMRI bagi setiap subjek dianalisis menggunakan pekej perisian MatLab dan SPM2. Model linear am (GLM) digunakan untuk menganggar secara statistik parameter yang mencirikan model rangsangan hemodinamik bagi gerakan jari. Kesimpulan mengenai pengaktifan otak yang diperhatikan dijana secara statistik berasaskan teori medan rawak (RFT) Gaussian. Keputusan menunjukkan bahawa rantau otak yang aktif akibat gerakan jari adalah pada girus presentral merangkumi kawasan motor primer. Pengaktifan otak adalah secara kontralateral terhadap gerakan jari tangan kanan dan kiri. Keamatan isyarat keadaan aktif didapati lebih tinggi secara bererti (p < 0.001) daripada keamatan isyarat keadaan rehat. Bilangan voksel yang aktif didapati lebih tinggi pada hemisfera otak yang mengawal gerakan jari bagi tangan yang tidak dominan untuk kedua-dua subjek. Keputusan ini menyokong fakta bahawa kawasan pengaktifan motor pada hemisfera otak semasa gerakan jari tangan yang tidak dominan mengalami rangsangan hemodinamik yang lebih tinggi dan kawasan pengaktifan yang lebih luas berbanding dengan kawasan pengaktifan pada hemisfera otak yang mengawal gerakan jari bagi tangan yang dominan.

Matched MeSH terms: Magnets

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