N. Abdullah

Growth Pattern of Zinc Oxide Nanorods on Gold Coated Silicon Surfaces

Nanostructured ZnO nanorods on gold (Au) coated silicon (Si) surfaces were made by solution method immerse technique, using (ZnNO3)2/HMTA at 80° C. The seed surfaces of Au were sputter‐coated on Si substrates, in which Au thicknesses were affected by current and sputter‐coating time. The morphology of the prepared nanostructure was analysed by scanning electron microscope (SEM), and the structural identification of the ZnO nanorods was carried out using X‐ray diffraction in the range of 2θ between 30°–60°. The growth intensity of ZnO nanorods on the substrate was found to be consistent from 3 nm to 12 nm of Au, at 15 nm there is a tremendous drop in growth. The resulting (hkl) peaks were found to be lattice planes of (100), (002), (101), (102) and (110). The presence of Au at thickness 3–12 nm gave preferential orientation of Zn (100), (002) and (101), though at different intensity.

Shape model of the maxillary dental arch using fourier descriptors with an application in the rehabilitation for edentulous patient

The knowledge of teeth positions on the maxillary arch is useful in the rehabilitation of the edentulous patient. A combination of angular (θ), and linear (l) variables representing position of four teeth were initially proposed as the shape descriptor of the maxillary dental arch. Three categories of shape were established, each having a multivariate normal distribution. It may be argued that 4 selected teeth on the standardized digital images of the dental casts could be considered as insufficient with respect to representing shape. However, increasing the number of points would create problems with dimensions and proof of existence of the multivariate normal distribution is extremely difficult. This study investigates the ability of Fourier descriptors (FD) using all maxillary teeth to find alternative shape models. Eight FD terms were sufficient to represent 21 points on the arch. Using these 8 FD terms as an alternative shape descriptor, three categories of shape were verified, each category having the complex normal distribution.

A novel shape representation of the dental arch and its applications in some dentistry problems

Standardized digital images of maxillary dental casts of 47 subjects were analyzed using MATLAB software whereby the two hamular notches and the incisive papilla defines the Cartesian vertical and horizontal axes, as well as the origin. The angle and length of the midpoints of the anterior teeth, mesiobuccal and distobuccal cusp of the posterior teeth were measured from the origin and denoted as θ<inf>1</inf>, …, θ<inf>18</inf> and l<inf>1</inf>, …, l<inf>18</inf> respectively. These values were collectively used to represent the shape of each dental cast. Clustering and principal component analyses were employed to find possible groups of dental arches using the above measure of shape. The main result of this study is that the 3 groups of dental arch shape may be represented by the novel feature vector v<inf>k</inf>=(θ^k<inf>1</inf>, l^k<inf>1</inf>, θ^k<inf>3</inf>, l^k<inf>3</inf>, θ^k<inf>5</inf>, l^k<inf>5</inf>, θ^k<inf>13</inf>, l^k<inf>13</inf>), k=1, 2, 3. Knowledge of v^k implies three impression trays should be sufficient in a particular prosthetic dentistry application for Malaysian patients. Further, given that v^k are accurately measured they may be potential candidates as evidence in specific application of forensic dentistry.

A Surface Morphology Study On The Effect Of Annealing Temperature To Nanostructured ZnO And Its Reaction Mechanism In Solution Method

Nanocrystalline zinc oxide (ZnO) were grown on silicon (Si) substrates by sol‐gel spin coating, without the presence of metal catalyst. In the process, annealing temperatures were varied from 350–500° C and it was found that increasing the annealing temperature had improved the crystalline structure of ZnO. The reaction mechanism of sol‐gel process forming ZnO was also suggested.

Surface morphology study on effect of deposition temperature on nanostructured zinc oxide by chemical vapour deposition method

Abstract Nanocrystalline ZnO was grown on Si and porous Si substrates, by chemical vapour deposition without metal catalyst. Increasing deposition temperature from 400 to 450°C at 0·5 L min–1 Ar flow rate, exhibited an improvement in the spread of ZnO, and smaller clusters of ZnO. At the same temperature range in Ar flow rate of 0·4 L min–1, ZnO nanoflower was formed.

A probability distribution of shape for the dental maxillary arch using digital images

Selected landmarks from each of 47 maxillary dental casts were used to define a Cartesian-coordinate system from which the positions of selected teeth were determined on standardized digital images. The position of the i-th tooth was defined by a line of length (li) joining the tooth to the origin, and the angle (θi) of this line to the horizontal Cartesian axis. Four teeth, the central incisor, lateral incisor, canine and first molar were selected and their position were collectively used to represent the shape of the dental arch. A pilot study using clustering and principal component analysis strongly suggest the existence of 3 groups of arch shape. In this study, the homogeneity of the 3 groups was further investigated and confirmed by the Dunn and Davies-Bouldein validity indices. This is followed by an investigation of the probability distribution of these 3 groups. The main result of this study suggests 3 groups of multivariate (MV) normal distribution. The MV normal probability distribution of these groups may be used in further studies to investigate the issues of variation of arch shape, which is fundamental to the practice of prosthodontics and orthodontics.

Effect of Functionalized Carbon Nanotubes in the Detection of Benzene at Room Temperature

In this paper, carbon nanotubes (CNTs) were functionalized by acid treatment and further functionalized with dodecylamine and were designated as CNT-carboxylic and CNT-amide, respectively. Then, functionalized CNTs produced were characterized with various methods to verify the attachment of a functional group. Performance of the functionalized CNTs in the detection of benzene gas was monitored at room temperature. The sample was dropped cast on the interdigitated transducer (IDT), and the changes in resistivity were recorded by a digital multimeter in a customized chamber under controlled humidity (∼55%) environment. Based on the findings, it showed that the functionalized CNTs provide an extra active area for interaction between the gas analyte and CNTs, thus increasing their response and improving the sensitivity of the sensing material.

The Influences of Chemical and Mechanical Treatment on the Morphology of Carbon Nanofibers

Oxidation by acid treatment is one of the chemical methods used to introduce surface oxygen functional group (SOFG) and defects on the surface of carbon nanofibers (CNFs). Therefore, many researchers used this method to improve the dispersion ability of CNFs in aqueous media. However, only few researchers used combination of chemical and mechanical method for oxidation of CNFs. In this work, as-received CNFs were treated using chemical method with an addition of mechanical method. On the first experiment (Method A) concentrated sulphuric acid and nitric acid were used and followed by combinations of mechanical method using ultrasonication water bath under reflux. The addition mechanical method through reflux was eliminated and different times of ultrasonication were used in method B and method C. Outer diameter of each CNFs samples were determined from FESEM images and were found to be in range of 50 nm–190 nm. Whereas, Raman spectroscopy was used to analyse any structural defects of CNFs samples during each treatment methods. From the findings, acid treatment of CNFs with addition of mechanical method using ultrasonication showed remarkably effect on the CNFs morphology.

Comparison and Characterization of Acid Functionalization of Multi Walled Carbon Nanotubes Using Various Methods

Functionalization of multiwalled carbon nanotubes (MWCNT) is one of several methods used to improve the compatibility of CNT. Even though acid functionalised method is effective, the strong acids such as H2SO4/HNO3 were normally employed and long hours of sonication is used to disperse the CNTs in the solution frequently can damage the nanotube, thus limiting their great performance as mechanical and electrical reinforcements. Here we are reporting comparison between three methods used in acid functionalized treatments of MWCNT. The first method, MWCNT was functionalized using ultra sonication water bath and followed by reflux (Method A). The second method, MWCNT was functionalized using ultrasonication water bath only for 2 hours (Method B). Finally, the third method MWCNT was functionalized using ultrasonication water bath only for 6 hours (Method C). Raman spectroscopy measurements were used to examine the general relationship between the chemical treatment and the amount of non-graphitic carbon. Electron microscopy analysis revealed that MWCNT functionalized using Method C suffered the highest degree degradation such as, nanotube shortening and additional defect generation in the graphitic network. Method B proved to be the most effective for this aim.

Synthesis and Adsorption Performance of Carbon Materials for the Removal of Iron (III) from Aqueous Solution.

Carbon nanofibers prepared from Ni catalyst supported on activated carbon and pre-treated activated carbons show the potential in removing borderline and soft metal Fe (III) ions in single solutions over a wide range of concentrations. The morphological and textural properties of the carbon material were studied using the Scanning Electron Microscope (SEM) and Nitrogen adsorption isotherm method. Continuous column adsorptions were conducted to study the adsorption performance. The results showed that the percentage of Fe (III) removal starts to increase at the initial concentration of 10 mg/L. The percentage of Fe (III) removal continues to increase until it reaches the maximum removal at 60 mg/L. The value of correlation (R2) indicates that the data on carbon-based adsorption of Fe (III) may be concluded to perfectly fit the Langmuir isotherm model confirms the monolayer adsorption. Thus, this study is relatively useful in considering an appropriate technology for designing a suitable wastewater treatment plant.