Papers by Shahidan Radiman
An unpublished paper presented at a local National Physics seminar 1990
on cubic lyotropic phase... more An unpublished paper presented at a local National Physics seminar 1990
on cubic lyotropic phases from IPMS perspective
ASM Science Journal
Iron oxide nanoparticles are utilised in a broad range of applications (magnetic data storage, bi... more Iron oxide nanoparticles are utilised in a broad range of applications (magnetic data storage, biosensing, drug delivery, treatment and remediation of contaminated soil and groundwater); causing noticeable quantities of iron oxide nanoparticles to be released into the environment. In this study, aggregation and stability of iron oxide nanoparticles in water were investigated within the range of pH 3 – pH 9 at a constant concentration of iron oxide nanoparticles and humic acid. The pH of the solution was selected to be continuously monitored at pH 7 to investigate the transportation and deposition behaviour of iron oxide nanoparticles in porous media at different velocities. It was found that iron oxide nanoparticles were aggregated and settle down as settled particles at low pH (pH 3 – pH 5). Iron oxide nanoparticles were stable, mobile and transported at a high pH, which is the pH range of natural water (pH 6.5 – pH 8.5). Iron oxide nanoparticles were strongly attached to the silic...
Sains Malaysiana, 2019
The scenario of released nanoparticles from consumer products into the environment especially nat... more The scenario of released nanoparticles from consumer products into the environment especially natural waters has become a great concern nowadays. Assessing their aggregation and stability under environmental conditions is important in determining their fate and behavior in natural waters. The aggregation behavior of selected nanoparticles (iron oxide and alumina) was investigated at variable concentrations of humic acid (5, 10, 50 mg/L), and pH variation in solution. Dynamic light scattering was used to measure their z-average hydrodynamic diameter and zeta potential. Derjaguin-Landau-Verwey-Overbeak (DLVO) theory was used to explain the thermodynamic interactions between two particles. Then, the stability was evaluated by assessing their aggregation. The increasing of humic acid concentrations enhanced aggregation of iron oxide and alumina nanoparticles, particularly at low pH levels. The maximum aggregation was found in pH below the point of zero charge (PZC) due to electrostatic destabilization and electrostatic stabilization that took place at pH above the point of zero charge. Meanwhile, at pH point of zero charge, nanoparticles were coated with negative humic acid charged. From this study, properties of nanoparticles (size, surface charge, Hamaker constant) and environmental condition (humic acid concentration, pH) have their specific roles to control the fate and behavior of nanoparticles in environmental media.
Le Journal de Physique Colloques, 1990
We have studied the cubic phase formed by the ternary system water/didodecyldimethylammonim bromi... more We have studied the cubic phase formed by the ternary system water/didodecyldimethylammonim bromideloctane using small-angle x-ray and neutron scattering. We have observed the existence of more than one symmetry in this cubic region, with a transition from primitive to body centred cubic symmetry on increasing the water content of the system. Our results are consistent with a bicontinuous periodic structure of constant mean curvature. We also report rheological measurements which indicate that the ringing behaviour of the cubic samples is associated with a sharp increase in the quality factor as audible frequencies are approached.
Journal de Physique, 1990
We report a small-angle X-ray and neutron scattering investigation in the cubic phase of the tern... more We report a small-angle X-ray and neutron scattering investigation in the cubic phase of the ternary system water/didodecyldimethyl ammonium bromide (DDAB)/octane. We have observed a systematic variation in the lattice parameter as a function of water content, which can be related to the change in interfacial area per unit cell with the aqueous volume fraction. Our results are consistent with a bicontinuous periodic constant mean curvature structure, and show a transition from diamond to body-centred cubic symmetry on increasing the water content of the system.
AIP Conference Proceedings, 2013
Electrochemical technique has been used to study the electrodeposition of cobalt, nickel, iron an... more Electrochemical technique has been used to study the electrodeposition of cobalt, nickel, iron and Co-Ni-Fe alloy on indium tin oxide (ITO) coated glass substrate. To obtain the nucleation mechanism, cyclic voltammetry is used to characterize the Co-Ni-Fe system. The scanning rate effect on the deposition process was investigated. Deposition of single metal occurs at potential values more positive than that estimated stability potential. Based on the cyclic voltammetry results, the electrodeposition of cobalt, nickel, iron and Co-Ni-Fe alloy clearly show that the process of diffusion occurs is controlled by the typical nucleation mechanism.
Philosophical Magazine A, 2002
... This may be because, in liquid quenched Al-Si alloys, the solubility of Si in a-A1 depends on... more ... This may be because, in liquid quenched Al-Si alloys, the solubility of Si in a-A1 depends on the overall Si content of the alloy. The maximum metastable solubility occurs at 13-14at.Yo Si (Van Rooyen and Mittemeijer 1989) and at 15at.%Si (Bendijk et al. 1980). ...
My first experience of travelling to Jhang -Pakistan
Sains Malaysiana, 2011
Nanozarah zink oksida telah disintesis menggunakan afrons gas koloid sebagai acuan. Zink sulfat (... more Nanozarah zink oksida telah disintesis menggunakan afrons gas koloid sebagai acuan. Zink sulfat (ZnSO 4 .7H2O) dan gas ammonia digunakan sebagi bahan tindak balas. Masa pengeraman yang dikaji adalah 2 jam dan 18 jam. Daripada analisis mikroskop elektron imbasan, morfologi nanohelaian dapat diperhatikan dengan ketebalan helaian 125 nm hingga 200 nm. Daripada analisis spektroskopi ultra lembayung-boleh nampak, saiz purata yang dianggarkan bagi sampel nanozarah zink oksida yang disintesis dengan masa pengeraman 2 jam adalah 2.03 nm dan 2.1 nm untuk sampel yang dieramkan selama 18 jam.
Luminescence, 2019
Gd 2 O 2 S:Eu 3+ nanophosphors have been successfully synthesized using microwave irradiation and... more Gd 2 O 2 S:Eu 3+ nanophosphors have been successfully synthesized using microwave irradiation and γ-irradiation methods with polyvinyl pyrrolidone as a stabilizer. The physical and luminescence spectra were compared. The morphologies of both Gd 2 O 2 S:Eu 3+ nanophosphors were in the hexagonal phase and mainly consisted of spherical nanostructures with diameters of~90 nm and~50 nm for both microwave irradiation and γ-irradiation methods. Upon 325 nm of ultraviolet (UV) light excitation, strong red emissions (626 nm) were observed for both methods; these emissions corresponded to the 5 D 0 → 7 F 2 transition of Eu 3+ ions. However, Gd 2 O 2 S:Eu 3+ nanophosphors following microwave treatment showed better luminescence intensity than Gd 2 O 2 S:Eu 3+ nanophosphors treated with γ-irradiation. This difference was attributed to the crystallinity phase and surface quenching effects of Gd 2 O 2 S: Eu 3+ nanophosphors. The reaction mechanisms of Gd 2 O 2 S:Eu 3+ nanophosphors in both methods are discussed in detail.
AIP Conference Proceedings, 2014
Many of the cellular process depend on the ability of the membrane to separate areas while allowi... more Many of the cellular process depend on the ability of the membrane to separate areas while allowing exchange and tightly regulated transport of material within and across the membrane to occur, which is the driving principle behind cell communication. The complexity of biological membranes has motivated the development of a wide variety of simpler model systems whose size, geometry and composition can be tailored with precision. This study was conducted to investigate the interactions between silica nanoparticles and Dipalmitoylphosphatidylcholine (DPPC) vesicles. The size range of DPPC vesicles formed was from 50 to 150 nm. Concentration of silica added to the vesicles was varied from 0.25 to 1.5 mg/ml. The change in vesicle size distribution, localization and positioning of silica nanoparticles in vesicles was studied via transmission electron microscopy (TEM) and differential scanning calorimetry (DSC).
Radiation Protection Dosimetry, 2007
Journal of Physics: Conference Series, 2013
In order to obtain a desirable deposition thickness, nanostructured ternary CoNiCu alloys have be... more In order to obtain a desirable deposition thickness, nanostructured ternary CoNiCu alloys have been electrodeposited from salt solutions containing Co 2+ , Ni 2+ and Cu 2+ in the presence of a neutral surfactant alkyl polyglucoside (APG). Electrodeposition of CoNiCu was carried out in a three-electrode cell with indium-tin oxide (ITO) on glass plate, platinum wire and saturated calomel electrode (SCE) as working electrode, counter electrode and reference electrode, respectively. The nanostructured alloys were characterized by means of atomic force microscopy (AFM) and supported by field emission scanning electron microscopy (FESEM). The nanostructured CoNiCu alloys prepared in sulphate solutions in the presence of APG produced a thinner layer of nanoparticles of the alloys compared with the one deposited in the absence of APG. For a fixed deposition time, 160s and at an applied potential of-875mV (SCE) the layer thickness was about 56 nm for electrodepositionin the presence of 3.25 wt.% APG and about 110 nm without APG. Only a small increase in thickness was observed when the potential was increased to more negative values i.e.-875 to-950 mV(SCE).
Journal of Macromolecular Science, Part A, 2007
... [CrossRef], [Web of Science ®] View all references, (d) sulfoxides 2525. Varma, RS, Saini, RK... more ... [CrossRef], [Web of Science ®] View all references, (d) sulfoxides 2525. Varma, RS, Saini, RK and Meshram, HM 1997. Tetrahedron Lett. ... [CrossRef], [Web of Science ®] View all references, manganese dioxide on silica 3636. Varma, RS, Saini, RK and Dahiya, R. 1997. ...
The evolution of microemulsion microstructure formed from didodecyl dimethyl ammonium bromide, wa... more The evolution of microemulsion microstructure formed from didodecyl dimethyl ammonium bromide, water and cyclohexane which started from being structureless (fiat scattering profile) to a mean-field Ginsburg-Landau behaviour is shown. The evolution gave the characteristic Lorentzian scattering profile as the system approaches phase separation.
Applied Mechanics and Materials, 2015
Two glycolipids were synthesized to study the lyotropic behavior of these glycolipids in alkylglu... more Two glycolipids were synthesized to study the lyotropic behavior of these glycolipids in alkylglucoside/water/n-octane ternary system. These glycolipids have been distinguished based on the structure of alkyl chain (branched-alkyl chain and straight alkyl chain). 2-octyl-β-D-glucopyranoside (2-OG) and 2-ethylhexyl-β-D-glucopyranoside (2-EHG) were used as surfactants to perform two types of phase diagram. Phase behaviours investigated were phase behaviours of 2-OG/n-octane/water ternary system and 2-EHG/n-octane/water ternary system. Small angle x-ray (SAXS) and optical polarizing microscope were used as the instruments to study the lyotropic phase behaviour of these two surfactans in ternary phase diagram. Study the effect of branched-tail structure on the phase behaviour of glycolipids in ternary system is one of strategy to derive the structure-property relationship. For this purpose, 2-OG and 2-EHG were used as surfactants in the same ternary system. The phase diagram of 2-OG/wat...
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Papers by Shahidan Radiman
on cubic lyotropic phases from IPMS perspective
on cubic lyotropic phases from IPMS perspective