Displaying publications 21 - 40 of 43 in total

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  1. 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
  2. Fulltext Magnetically-Actuated Mixing and Merging of Acid-Base Micro-Droplets on Open Surfaces: Preliminary Study
    Khaw MK, Mohd-Yasin F, Nguyen NT
    Sensors (Basel), 2018 Jun 01;18(6).
    PMID: 29857584 DOI: 10.3390/s18061767
    We present the mixing and merging of two reactive droplets on top of an open surface. A mobile droplet (1.0 M HCl solution + iron oxide particles) is magnetically-actuated to merge with a sessile droplet (1.0 M NaOH + phenolphthalein). The heat from the exothermic reaction is detected by a thermocouple. We vary the droplet volume (1, 5 and 10 μL), the magnet speed (1.86, 2.79, 3.72 and 4.65 mm/s) and the iron oxide concentration (0.010, 0.020 and 0.040 g/mL) to study their influences on the mixing time, peak temperature and cooling time. The sampled recording of these processes are provided as supplementary files. We observe the following trends. First, the lower volume of droplet and higher speed of magnet lead to shorter mixing time. Second, the peak temperature increases and cooling time decreases at the increasing speed of magnet. Third, the peak temperature is similar for bigger droplets, and they take longer to cool down. Finally, we also discuss the limitations of this preliminary study and propose improvements. These observations could be used to improve the sensitivity of the open chamber system in measuring the exothermic reaction of biological samples.
    Matched MeSH terms: Magnets
  3. Fulltext An Eddy Current Testing Platform System for Pipe Defect Inspection Based on an Optimized Eddy Current Technique Probe Design
    Rifai D, Abdalla AN, Razali R, Ali K, Faraj MA
    Sensors (Basel), 2017 Mar 13;17(3).
    PMID: 28335399 DOI: 10.3390/s17030579
    The use of the eddy current technique (ECT) for the non-destructive testing of conducting materials has become increasingly important in the past few years. The use of the non-destructive ECT plays a key role in the ensuring the safety and integrity of the large industrial structures such as oil and gas pipelines. This paper introduce a novel ECT probe design integrated with the distributed ECT inspection system (DSECT) use for crack inspection on inner ferromagnetic pipes. The system consists of an array of giant magneto-resistive (GMR) sensors, a pneumatic system, a rotating magnetic field excitation source and a host PC acting as the data analysis center. Probe design parameters, namely probe diameter, an excitation coil and the number of GMR sensors in the array sensor is optimized using numerical optimization based on the desirability approach. The main benefits of DSECT can be seen in terms of its modularity and flexibility for the use of different types of magnetic transducers/sensors, and signals of a different nature with either digital or analog outputs, making it suited for the ECT probe design using an array of GMR magnetic sensors. A real-time application of the DSECT distributed system for ECT inspection can be exploited for the inspection of 70 mm carbon steel pipe. In order to predict the axial and circumference defect detection, a mathematical model is developed based on the technique known as response surface methodology (RSM). The inspection results of a carbon steel pipe sample with artificial defects indicate that the system design is highly efficient.
    Matched MeSH terms: Magnets
  4. Anomalous Temperature Dependence of Electrical Resistivity in Mg0.6Zn0.4Fe2O4 Ferrite
    Mustafa Hj. Abdullah, Ahmad Nazlim Yusoff
    Sains Malaysiana, 1996;25.
    The electrical resistivity of Mg0.6Zn0.4Fe2O4 ferrite was measured as a function of temperature in the range 300-630 K. Two anomalies are observed in the resistivity curves for measurements during heating up. These anomalies are identified as a magnetic anomaly at the Neel temperature, TN = 598 K, while the other one at TOt = 445 K is discussed as due to the contribution of conduction from the tetrahedral sites. The anomaly at Tot was reduced in the measurements during recooling, while the anomaly at TN was disappeared completely during recooling and second cycle. These effects are discussed as due to the increase of Fe2+ ions at the octahedral sites as a result of cation redistribution at higher temperatures. A relatively small anomaly at Tot still can be observed during the second run. This is possible if the Fe2+ ions have a preference to be relocated at the tetrahedral sites at lower temperatures.
    Kerintangan elektrik Mg0.6Zn0.4Fe2O4 ferit telah diukur sebagai fungsi suhu dalam julat 300 - 630 K. Dua anomali dapat dicerap pada lengkung kerintangan bagi pengukuran semasa pemanasan. Dua anomali tersebut dikenalpasti sebagai anomali magnet pada suhu Neel, TN = 598 K, manakala yang satu lagi pada Tot = 445 K dibincangkan sebagai berpunca daripada sumbangan kekonduksian pada tapak tetrahedron. Anomali pada Tot mengurang dalam pengukuran semasa penyejukan semula pada julat suhu yang sarna, manakala anomali pada TN terus lenyap dalam pengukuran semasa penyejukan semula dan juga semasa kitar kedua. Kesan ini dibincangkan sebagai disebabkan oleh peningkatan ion Fe2+ pada tapak oktahedron daripada proses taburan semula kation pada suhu tinggi. Anomali yang berkurang pada Tot masih boleh dicerap semasa pengukuran kitar kedua. Keadaan seperti ini adalah mungkin jika ion Fe2+ mempunyai kecenderongan untuk bertempat semula pada tapak tetrahedron apabila suhu menurun.
    Matched MeSH terms: Magnets
  5. Simulation and statistical approaches on electrical steel's magnetic behaviour under unidirectional single sheet tester
    Noor Ashikin Mohd Rashid, Wan Nor Liza Wan Mahadi
    Sains Malaysiana, 2014;43:909-914.
    Evaluation of magnetic properties of electrical steel is vital in improving the quality of electrical machinery since it is used as magnetic cores for transformers, motors and generators. A double yoke single sheet tester (ssT) was modeled using two identical C-cores wound with copper wires at limb side in horizontal arrangement. The magnetic properties for electrical steels, grade M4 and M19 were tested under a frequency of 50 Hz with the current ranging from 02 to 2.4A. The effects of the sample dimension and anisotropy on magnetic measurements were investigated. Evaluation on specimen dimensions indicate that the non-uniformity of sample magnetization in overhang sample can attribute to the flux leakage between the yoke legs. The stray flux is also increased with the overhang sample. However, the so-called fit-in sample which is fitted nicely between the yoke end poles can minimize the effect of stray flux. One way ANOVA and T-test were used as statistical methods and executed at the 5% significance level. It is statistically proven that the magnetic properties of both magnetic materials are influenced by their anisotropy.
    Matched MeSH terms: Magnets
  6. Electrical and magneto-transport properties of magneto-resistive La 0.7 Ca 0.28 Sr 0.2 MnO3 prepared at different sintering temperature
    Ewe L, Ramli R, Lim K, Abd-Shukor R
    Sains Malaysiana, 2012;41:761-768.
    The effects of strontium doping on the electrical and magneto-transport properties of magneto resistive La0.7Ca0.28Sr0.02MnO3 at different sintering temperatures have been studied. The samples were prepared by the co-precipitation technique (COP) and sintered at 1120, 1220 and 1320 oC. XRD patterns revealed that the samples have an orthorhombic structure and the diffraction patterns can be indexed with the Pbnm space group. The insulator metal transition, TIM increased linearly from 261 K to 272 K with the increase in sintering temperature. The magnetoresistance (MR) measurements were made in magnetic fields from 0.1 to 1 T at room temperature. The percentage of MR increased with increasing of magnetic field and sintering temperature for all samples. The electrical resistivity data were fitted with several equations in the metallic (ferromagnetic) and insulator (paramagnetic) regime. The density of states at the Fermi level N(EF) and the activation energy (Ea) of electron hopping were estimated by using variable range hopping and small polaron hopping model.
    Matched MeSH terms: Magnets
  7. 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
  8. 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
  9. 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
  10. 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
  11. 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
  12. 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
  13. 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
  14. 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*
  15. 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*
  16. 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*
  17. 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
  18. 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
  19. 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
  20. Effects of Yttria Doping on Some Properties of YBa2Cu3O7-δ 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
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