Hashim Saim

Interfacial study of cell adhesion to liquid crystals using widefield surface plasmon resonance microscopy

Widefield surface plasmon resonance (WSPR) microscopy provides high resolution imaging of interfacial interactions. We report the application of the WSPR imaging system in the study of the interaction between keratinocytes and liquid crystals (LC). Imaging of fixed keratinocytes cultured on gold coated surface plasmon substrates functionalized with a thin film of liquid crystals was performed in air using a 1.45NA objective based system. Focal adhesion of the cells adhered to glass and LC were further studied using immunofluorescence staining of the vinculin. The imaging system was also simulated with 2×2 scattering matrix to investigate the optical reflection of the resonant plasmonic wave via the glass/gold/cell and glass/gold/LC/cell layers. WSPR imaging indicated that keratinocytes are less spread and formed distinct topography of cell-liquid crystal couplings when cultured on liquid crystal coated substrates. The simulation indicates that glass/LC shifted the surface plasmon excitation angle to 75.39° as compared to glass/air interface at 44°. The WSPR microcopy reveals that the cells remodelled their topography of adhesion at different interfaces.

Zinc oxide microrods prepared by sol-gel immerse technique

Purpose – Zinc oxide (ZnO) is an emerging optoelectronic material due to its various functional behaviors. The purpose of this paper is to report on the fabrication and characterizations of ZnO microrods.Design/methodology/approach – ZnO microrods were synthesized using sol‐gel immerse technique on oxidized silicon (Si) substrates. The oxidized Si substrates were immersed in ZnO aqueous solution for different times ranging from three to five hours. The surface morphologies of the ZnO microrods were examined using scanning electron microscope (SEM). In order to investigate the structural properties, the ZnO microrods were measured using an X‐ray diffractometer (XRD). The optical properties were measured using a photoluminescence (PL) spectrophotometer.Findings – Characterization from SEM shows an enhanced growth of the ZnO rods with increasing immerse time. XRD characterizations demonstrate sharp and narrow diffraction peaks peculiar to ZnO, which implies that the rod is of high crystallinity. Based on the...

Changes in physical properties and molecular structure of polystyrene nanospheres exposed with daily solar flux

The effects of physical properties and molecular structure of 200 nm polystyrene nanospheres (PSN) coated on silicon wafer exposed with daily solar flux were explored by field emission scanning electron microscope (FE-SEM) and attenuated total reflectance-Fourier transform infrared (ATR-FT-IR) spectrometer. It is revealed that the particles shape of PSN changed from spheric to eight-shaped after solar radiation. Reduction of the size as much as 29.5% after 5 minutes exposure was also observed in PSN particles. Changes in the molecular structure of the PSN particles after solar radiation were observed where some of the phenyl moieties of polystyrene broke down to facilitate carbon-carbon cross linkage bonds. These results demonstrated that the shrinkage of PSN particles is caused by the change of the molecular structure of polystyrene.

Surface Morphology and Optical Properties of ZnO Films Synthesis Using Different Solvent

Zinc oxide (ZnO) is a promising electronic material for a variety of large area electronic applications including thin-film sensors, transistors, and solar cells. Various techniques have been focused and explored to synthesize ZnO films. In this study, sol-gel process was adopted as the fabrications process to grow the ZnO films. Three different types of solvents were used including ethanol, isopropanol and ethylene glycol as the reaction medium in the ZnO solution. The correlation between different solvents used and the properties of the ZnO films was explored and observed. The surface morphologies, structural and optical properties were examined using field émission scanning electron microscope (FESEM), X-ray diffractometer (XRD) and ultraviolet-visible (UV-Vis) spectroscopy. Through the observation from FESEM results, the surface morphology changed when different solvents were used. The crystallographic structures of the ZnO films demonstrate high crystallinity, and the extracted crystallite size is around 30 nm. Furthermore, ZnO films synthesized using isopropanol and ethylene glycol exhibit high transmittance spectra greater than 80% in the visible region. In general, the experimental results revealed that different solvents in the sol-gel process exert influences on the properties of the ZnO films.

A study on the ergonomic assessment in the workplace

Ergonomics has gained attention and take into consideration by the workers in the different fields of works recently. It has given a huge impact on the workers comfort which directly affects the work efficiency and productivity. The workers have claimed to suffer from the painful postures and injuries in their workplace. Musculoskeletal disorders (MSDs) is the most common problem frequently reported by the workers. This problem occurs due to the lack of knowledge and alertness from the workers to the ergonomic in their surroundings. This paper intends to review the approaches and instruments used by the previous works of the researchers in the evaluation of the ergonomics. The two main assessment methods often used for ergonomic evaluation are Rapid Upper Limb Assessment (RULA) and Rapid Entire Body Assessment (REBA). Popular devices are Inertial Measurement Units (IMU) and Microsoft Kinect.

Zinc Oxide Nanostructures for Efficient Energy Conversion in Organic Solar Cell

We present a new approach of solution-processed using zinc oxide (ZnO) nanostructures as extraction layer material for organic solar cells. It is low chemical reaction compatibility with all types of organic blends and its good adhesion to both surfaces of ITO/glass substrate and the active layer (blends). Parameters such as the thickness and the morphology of the films were investigated to prove that these factors greatly affect the efficiency of organic solar cells. In this work, ZnO layer with thickness of approximately 53 nm was used as an interlayer to prevent pin-holes between the electrode and the polymer layer. The polymer layer was coated on the ZnO layer with the thickness of about 150 nm. The thick polymer layer will form a non-uniform surface because of the solvent, 1-2dichlorobenzene will etch away some region of the polymer layer and forming pin-holes. ZnO nanostructures layer was used to prevent pin-holes between the polymer layer and electrode. From the surface morphology of ZnO layer, it shows a uniform surface with particle grain size obtained between 50 -100 nm. The presence of the interlayer has a positive effect on the electrical characteristics of the solar cells. It was found that an organic solar cell with thickness less than 150 nm shows the optimum performance with efficiency of 0.0067% and Fill Factor (FF) of about 19.73.

Sol‐Gel Fabrications of ZnO Thin Films and Microstructures

Zinc oxide (ZnO) thin films, micro‐ and nanostructures are promising candidates for applications in optoelectronic devices. In this work, low cost sol‐gel spin coating and hydrothermal techniques were used to fabricate the ZnO films on glass substrates and ZnO microstructures on oxidized silicon substrates, respectively. The structural properties of the ZnO samples were examined using scanning electron microscope (SEM) and atomic force microscope (AFM). The influence of precursor concentration in the sol‐gel processes on the properties of the ZnO films and microstructures was investigated and will be discussed in this paper.

Microfabrication of ZnO structures using sol-gel immerse technique

Zinc oxide (ZnO) is an emerging material in large area electronic applications such as thin-film solar cells and transistors. We report on the fabrication and characterization of ZnO nanostructures. ZnO nanostructures have been synthesized using sol-gel immerse technique on oxidized silicon substrates. Different precursors concentrations ranging from 0.0001 M to 0.01 M (M=molarity) using zinc nitrate hexahydrate [Zn(NO3)2.6H2O] and hexamethylenetetramine [C6H12N4] were employed in the synthesis of the ZnO nanostructures. The surface morphologies were examined using scanning electron microscope (SEM) and the structural properties were measured using X-ray diffractometer (XRD). In order to investigate the optical properties, the ZnO nanostructures were measured using ultraviolet-visible (UV-Vis) spectroscopy. The electrical properties of the ZnO nanostructures were characterized using current-voltage (I-V) measurement system.

Effect of Immerse Duration on the Structural and Optical Properties of Zinc Oxide Nanorod

Zinc oxide (ZnO) is an emerging optoelectronic material in large area electronic applications that are due to its various functional behaviors. We present the fabrication and characterizations of ZnO nanorods. The ZnO nanorods were synthesized using sol-gel hydrothermal technique on oxidized silicon (Si) substrates. In the fabrication of ZnO nanorods, the oxidized Si substrates were immersed in ZnO aqueous solution for different durations ranging from 3 hours to 5 hours. The surface morphologies of the ZnO nanorods were examined using scanning electron microscope (SEM). In order to investigate the structural properties, the ZnO nanorods were measured using X-ray diffractometer (XRD). The optical properties were measured using ultraviolet-visible (UV-Vis) spectroscopy. The effect of the immerse duration on the material properties of the realized ZnO nanorods will be revealed and discussed in this paper.

Nucleation and growth of chrysanthemum-like zinc oxide crystals using silicon dioxide

Abstract The chrysanthemum-like ZnO crystal has been grown by dry oxidation process in the sol–gel method. The samples have been characterised using SEM and XRD. The surface morphology of SEM result shows that the structure is like a chrysanthemum flower. The chrysanthemum-like crystal has been synthesised and composed of one-dimensional nanorods which have hexagonal wurtzite structure. It is also shown that the nanorods were preferentially grown along the [001] direction. In this paper, the growth mechanism and synthesis technique of chrysanthemum-like nanostructured ZnO are explained in detail.