Study of magnetic properties of nanostructures on self-assembled patterns

>Magister Scientiae - MScIn the current study, we give a report when oxalic acid was used as an electrolyte to synthesize an AAO template with hexagonal pore array. Optimum parameters were observed as 0.4 M of oxalic acid, anodizing voltage of 45 V, temperature of approximately 8 °C and the period of 120 minutes. Atomic force microscope (AFM) and High resolution scanning electron microscope (HRSEM) showed that template has an average pore diameter of 103 nm. Co and MnOx (x = 1,2) nanostructures were selectively deposited in the pores of the template using a novel atomic layer deposition (ALD) technique. The diameter sizes and the array of the nanostructures and the template were corresponding. Energy dispersive xrays (EDX) and X-ray photoelectron spectroscopy (XPS) confirmed the presence of Co and MnOx (x =1,2) on the samples while x-ray diffraction (XRD) provided an indication of their orientations. Magnetic force microscopy as main characterization tool showed the existence of multi-domains on both Co and MnOx (x =1,2) nanostructures.South Afric

Self-catalytic growth of tin oxide nanowires by chemical vapor deposition process

We report on the synthesis of tin oxide (SnO2) nanowires by a chemical vapor deposition (CVD) process. Commercially bought SnO nanopowders were vaporized at 1050∘C for 30 minutes with argon gas continuously passing through the system. The assynthesized products were characterized using UV-visible absorption spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The band gap of the nanowires determined from UV-visible absorption was around 3.7 eV.The SEM micrographs revealed “wool-like” structure which contains nanoribbons and nanowires with liquid droplets at the tips. Nanowires typically have diameter in the range of 50–200nm and length 10–100 m. These nanowires followed the vapor-liquid-solid (VLS) growth mechanism

Self-Catalytic Growth of Tin Oxide Nanowires by Chemical Vapor Deposition Process

We report on the synthesis of tin oxide (SnO 2 ) nanowires by a chemical vapor deposition (CVD) process. Commercially bought SnO nanopowders were vaporized at 1050 ∘ C for 30 minutes with argon gas continuously passing through the system. The assynthesized products were characterized using UV-visible absorption spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The band gap of the nanowires determined from UV-visible absorption was around 3.7 eV. The SEM micrographs revealed "wool-like" structure which contains nanoribbons and nanowires with liquid droplets at the tips. Nanowires typically have diameter in the range of 50-200 nm and length 10-100 m. These nanowires followed the vapor-liquid-solid (VLS) growth mechanism

Comparative study: the effect of annealing conditions on the properties of P3HT:PCBM blends

This paper presents a detailed study on the role of various annealing treatments on organic poly(3-hexylthiophene) and [6]-phenyl-C61-butyric acid methyl ester blends under different experimental conditions. A combination of analytical tools is used to study the alteration of the phase separation, structure and photovoltaic properties of the P3HT:PCBM blend during the annealing process. Results showed that the thermal annealing yields PCBM ‘‘needle-like’’ crystals and that prolonged heat treatment leads to extensive phase separation, as demonstrated by the growth in the size and quantity of PCBM crystals. The substrate annealing method demonstrated an optimal morphology by eradicating and suppressing the formation of fullerene clusters across the film, resulting in longer P3HT fibrils with smaller diameter. Improved optical constants, PL quenching and a decrease in the P3HT optical bad-gap were demonstrated for the substrate annealed films due to the limited diffusion of the PCBM molecules. An effective strategy for determining an optimized morphology through substrate annealing treatment is therefore revealed for improved device efficiency.Web of Scienc

The study of bionanocomposite thin films and their crystal growth behaviour

Ph.D. (Chemistry)This study focuses on the morphology and crystal-growth behaviour of polyactide (PLA)-based blends and blends modified with organoclay thin films. The study further examined the effect of blending and the incorporation of organoclays on the enzymatic degradation behaviour. Thin films of unmodified and nanoclay-modified PLA/poly(butylene succinate) (PBS) blends were cast on a glass substrate by a spin coater, while thin films of biodegradable PLA/poly[(butylene succinate)-coadipate] PBSA blends and blends containing organoclays were cast on a silicon (100) wafer substrate. The morphology and crystal growth behaviour of the thin films crystallized at different temperatures were examined with an atomic force microscopy (AFM) equipped with a hot-stage scanner. In PLA/PBS blend thin films, AFM images showed that the size of the dispersed PBS phase was influenced by C30B clay loading on the blends. The dispersed size reduced on the addition of C30B clay up to 2 wt%, beyond which, dispersed size began to increase. Transmission electron microscopy studies indicated that this behaviour was due to the preferential location of silicates in the PBS phase than in the PLA phase. For thin films annealed at 60 °C, the additi on of organoclays to the blend quenched the growth of edge-on lamellae. The crystalline morphologies at 120 °C were dominated by edge-on lamellae grown, around the PBS phase to form spherulites. Morphologies of thin films crystallized at 120 °C from melt were dominated by the flat-on lamellae, while those crystallized at 70 °C from melt were dominated by the edge-on lamellae. In the case of PLA/PBSA blend thin films, the results indicated that the size and distribution of the dispersed phase were directly related to the blend composition. The crystal growth behaviours indicated the presence of homogeneous and heterogeneous nucleations, and the nature of nucleation was directly related to the blend ratio and the temperature at which crystallization occurred. Therefore, this study will facilitate the understanding of crystal growth behaviour in a confined environment and will enable the modulation of the blend properties

Thermo-oxidative degradation study of melt-processed polyethylene and its blend with polyamide using time-resolved rheometry

Time-resolved mechanical spectroscopy (TRMS) was conducted to study the thermo-oxidative degradation of linear low density polyethylene (LLDPE) samples with different thermal histories and their blends with a polyamide (PA6) in the melt state. Neat LLDPE was first melt-processed at 180, 220, 250, and 260 °C in an extruder and then pre-processed LLDPE samples were further extruded with PA6 at 260 °C to form various LLDPE/PA6 blends. TRMS measurements were conducted under an air atmosphere at 0.5% strain and a constant frequency of 0.1 rad/s for LLDPE samples and at a range of frequencies between 0.1 and 60 rad/s for LLDPE/PA blend samples, over a 1 h period. In the case of LLDPE samples, time-sweep experiments were carried out at 190, 220, and 240 °C, whereas the temperature was fixed at 240 °C for the LLDPE/PA blend samples. The observed rheological behaviors revealed that the degradation resulted in an increase in the elastic moduli of the LLDPE and LLDPE/PA blends regardless of the thermal history. LLDPE processed at different processing temperatures produced different viscoelastic behaviors in cases where the LLDPE samples were processed at lower temperatures (180 and 220 °C) where a rapid increase in the modulus over a short period was seen. On the other hand, a change in the pre-processing temperature of the LLDPE had no effect on the rheological property of the corresponding LLDPE/PA6 blends. Cross-linking reactions during measurements under an air atmosphere could be the main reason for the growth in the modulus as a result of thermo-oxidative degradation. It was found that degradation was only a function of the temperature and exposure time, not the frequency. The most important result of this study was that collecting data on the isochronal moduli at different scanning frequencies was a more accurate way to understand the degree of cross-linking compared to running conventional frequency sweep tests, where the molecular structure of the material was unstable as a result of rapid degradation

The Application of the FibreLux Instrument for Measuring the Diameter of Mohair Fibres

ABSTRACTThe current study investigated the possible application of the FibreLux Micron MeterTM (FibreLux) instrument for the on-farm measurement of the diameter of greasy mohair staples. Initially, the effects of arrangement of the fibers in the specimen holder and that of solvent cleaning were investigated. It was found that a random arrangement of the fibers in the specimen holder produced more accurate and reproducible results, than when the fibers were aligned parallel (to the length of the specimen holder). The solvent cleaning had a statistically significant effect (p < .05) on the results, with the average of the mean fiber diameter (MFD) for the clean staple samples being 1.21 µm lower (finer) than that for the greasy staples. A good correlation (R = 0.95) was found between the FibreLux greasy staple results and those of the OFDA100 clean staples, the latter being used as the reference. The FibreLux values were, on average, some 0.80 µm lower than those of the OFDA100. It was concluded that the FibreLux holds significant promise for determining the fiber diameter of greasy mohair staples, but this should be validated by further trials, preferably “on farm” field trials, to determine the number of staples that need to be measured for each goat

Characterization of polypropylene/polystyrene boehmite alumina nanocomposites: Impact of filler surface modification on the mechanical, thermal, and rheological properties

The influences of surface treatment and the concentration of boehmite alumina (BA) particles on polypropylene and polystyrene (PS) (80/20) blends produced via melt compounding were examined. The results show that p-toluene sulfonic acid-treated BA particles yielded the highest stiffness improvement (27.5%), followed by untreated particles (25.7%), and dodecylbenzene sulfonic acid-treated BA particles (8.5%). Transmission electron microscopy revealed that p-toluene sulfonic acid-treated BA particle agglomerates were dispersed in the PS phase, whereas untreated particles formed agglomerations at the interfaces. Dodecylbenzene sulfonic acid-treated particles were poorly dispersed in both matrices. Differential scanning calorimetry showed that both untreated and p-toluene sulfonic acid-treated BA particles acted as nucleating agents in the blend because of the shifting of crystallization peaks to higher temperatures by 12 and 8 °C, respectively. A significant increase in decomposition temperatures occurred upon 7 wt % loading of all types of BA particles into the blend. Heat deflection temperature measurements showed that all types of BA particles improved the thermal properties of the blend

Sensing Technologies for Detection of Acetone in Human Breath for Diabetes Diagnosis and Monitoring

The review describes the technologies used in the field of breath analysis to diagnose and monitor diabetes mellitus. Currently the diagnosis and monitoring of blood glucose and ketone bodies that are used in clinical studies involve the use of blood tests. This method entails pricking fingers for a drop of blood and placing a drop on a sensitive area of a strip which is pre-inserted into an electronic reading instrument. Furthermore, it is painful, invasive and expensive, and can be unsafe if proper handling is not undertaken. Human breath analysis offers a non-invasive and rapid method for detecting various volatile organic compounds thatare indicators for different diseases. In patients with diabetes mellitus, the body produces excess amounts of ketones such as acetoacetate, beta-hydroxybutyrate and acetone. Acetone is exhaled during respiration. The production of acetone is a result of the body metabolising fats instead of glucose to produce energy. There are various techniques that are used to analyse exhaled breath including Gas Chromatography Mass Spectrometry (GC–MS), Proton Transfer Reaction Mass Spectrometry (PTR–MS), Selected Ion Flow Tube-Mass Spectrometry (SIFT–MS), laser photoacoustic spectrometry and so on. All these techniques are not portable, therefore this review places emphasis on how nanotechnology, through semiconductor sensing nanomaterials, has the potential to help individuals living with diabetes mellitus monitor their disease with cheap and portable devices

Effect of varying ethanol and water compositions on the acetone sensing properties of WO3 for application in diabetes mellitus monitoring

Tungsten oxide based gas sensors have attracted a lot of attention in breath acetone analysis due to their potential in clinical diagnosis of diabetes. The major problem with this material in sensor application has been remarkable response to all gases but low selectivity to specific gases. Herein, we report the gas sensing performance ofWO3 materials which were synthesized by varying water and ethanol ratios using a facile solvothermal method for acetone detection. The gas sensing properties of as-preparedWO3 were tested on acetoneC7H8,NO2, NH3,H2S andCH4 under relative humidity. X-ray diffraction patterns show that as-preparedWO3 samples are mainly composed of monoclinic WO3, a phase having relatively high selectivity to acetone. The as-preparedWO3 sensors produced using 51:49 ratio of water: ethanol show an increase in acetone response as the acetone concentration increases and a decrease in acetone response as the relative humidity increases. The sensor responded to a very low acetone concentration ranging from 0.5 to 4.5 ppm which is normally found in human breath. Furthermore, the sensor exhibited high sensitivity and selectivity to low ppm of acetone at 100 °C. On contrary, the sensor showed significantly lower response to other gases tested.CSIR-DSThttp://iopscience.iop.org/journal/2053-1591am2021BiochemistryGeneticsMicrobiology and Plant Patholog