A 38 year old patient unth. chronic granulocytes leukaemia, subsequently presented untli blast transformation. nineteen. months later. Conventional light microscopy and cytochemistry were not helpful in elucidating the type of blast cell. Electron microscopy however identifies the blasts to be of megakaryocytic series.
The concern about our dependency on non-renewable resources and overwhelming environmental issues such as pollution caused by non-degradable packaging materials has prompted researchers to come up with alternatives to solve this problem. Thermoplastic polylactic acid (PLA) has been gaining interest due to its versatility and easy processability, thus this study was carried out to find out the properties of PLA reinforced with pineapple fibers. However, surface of the natural fibers need to be treated for better properties enhancement in the polymer matrices. Considering this, fibers were treated with 10% (w/v) concentration of potassium hydroxide (KOH) and then continued for mixing with PLA at a fixed ratio of plasticizer by using internal mixer, and then the composites were prepared into sheet via hot press. Characterization for the mechanical and morphological was conducted by using tensile testing and scanning electron microscopy, respectively. After the analysis, it is found that the surface treated pineapple fiber composite showed better elongation at break compared to untreated fiber composite. The enhance properties of PLA nanocomposites has potential to be used in various packaging materials.
The existing mold concept of fabricating magnetorheological elastomer (MRE) tends to encounter several flux issues due to magnetic flux losses inside the chamber. Therefore, this paper presents a new approach for enhancing particle alignment through MRE fabrication as a means to provide better rheological properties. A closed-loop mold, which is essentially a fully guided magnetic field inside the chamber, was designed in order to strengthen the magnetic flux during the curing process with the help of silicone oil (SO) plasticizers. The oil serves the purpose of softening the matrix. Scanning electron microscopy (SEM) was used to observe the surface morphology of the fabricated MRE samples. The field-dependent dynamic properties of the MREs were measured several ways using a rheometer, namely, strain sweep, frequency sweep, and magnetic field sweep. The analysis implied that the effectiveness of the MRE was associated with the use of the SO, and the closed-loop mold helped enhance the absolute modulus up to 0.8 MPa. The relative magnetorheological (MR) effects exhibited high values up to 646%. The high modulus properties offered by the MRE with SO are believed to be potentially useful in industry applications, particularly as vibration absorbers, which require a high range of stiffness.
The aim of this paper is to evaluate the Mode II interfacial fracture toughness and interfacial shear strength of Typha spp. fiber/PLLA and Typha spp. fiber/epoxy composite by using a double shear stress method with 3 fibers model composite. The surface condition of the fiber and crack propagation at the interface between the fiber and the matrix are observed by scanning electron microscope (SEM). Alkali treatment on Typha spp. fiber can make the fiber surface coarser, thus increasing the value of interfacial fracture toughness and interfacial shear strength. Typha spp. fiber/epoxy has a higher interfacial fracture value than that of Typha spp. fiber/PLLA. Interfacial fracture toughness on Typha spp. fiber/PLLA and Typha spp. fiber/epoxy composite model specimens were influenced by the matrix length, fiber spacing, fiber diameter and bonding area. Furthermore, the interfacial fracture toughness and the interfacial fracture shear stress of the composite model increased with the increasing duration of the surface treatment.
Resistance spot welding (RSW) of dual phase (DP) steels is a challenging task due to formation of brittle martensitic structure in the fusion zone (FZ), resulting in a low energy capacity of the joint during high-rate loading. In the present study, in situ postweld heat treatment (PWHT) was carried out by employing a double pulse welding scheme with the aim of improving the mechanical performance of DP590 steel resistance spot weld joint. Taguchi method was used to optimize in situ PWHT parameters to obtain maximum peak load and failure energy. Experiments were designed based on orthogonal array (OA) L16. Mechanical performance was evaluated in terms of peak load and failure energy after performing low dynamic tensile shear (TS) test. Microstructural characterization was carried out using a scanning electron microscope (SEM). The results show that improvements of 17 and 86% in peak load and failure energy, respectively, were achieved in double-pulse welding (DPW) at optimum conditions compared to traditional single-pulse welding (SPW). The improvement in mechanical performance resulted from (i) enlargement of the FZ and (ii) improved weld toughness due to tempering of martensite in the FZ and subcritical heat affected zone (SCHAZ). These factors are influenced by heat input, which in turn depends upon in situ PWHT parameters.
OBJECTIVES: The aim of the present study was to test cutting efficiency of different materials against conventional alumina in an air abrasion system.
MATERIALS AND METHODS: The powder samples were divided into three groups: Group 1 - alumina (control), Group 2 - 45S5 bioactive glass, and Group 3 - hydroxyapatite. 30 microscope glass slides of 0.5 mm thickness were used as an alternative of human enamel and were also divided randomly into these three groups. The time taken by the abrasive particles to cut a hole through the microscope glass slide was recorded with a stop watch. In addition, morphology of the particles was observed through scanning electron microscopy (SEM). A t-test was used to compare the times taken to cut a hole through the microscope glass slides, and the level of significance was set at P < 0.05.
RESULTS: The mean time taken to cut a hole through the microscope glass slide was 2.96 s and 23.01s for Groups 1 and 2, respectively, whereas powder of Group 3 did not cut after 120 s. The differences between cutting times of Groups 1 and 2 were statistically significant (P < 0.05). The SEM micrographs revealed coarse angular shape for particles of Groups 1 and 2 but Group 3 particles were with round ends and presence of smaller particles was also observed in Groups 2 and 3.
CONCLUSION: The alumina particles demonstrated excellent cutting efficiency followed by 45S5 particles. The use of bioactive glass particles should be encouraged for cutting purposes whenever a shortage of time for practitioners is not a concern.
The microstructural evolution of Sn-40Pb/Cu joints has been investigated under 125 o C thermal exposure conditions using single shear lap joints. A scanning electron microscope (SEM) was used to observe the morphology of the phases and energy dispersive x-ray (EDX) was used to estimate the elemental compositions of the phases. A double layer of Cu6Sn5 and Cu3Sn were observed. The Cu6Sn5 developed with a scalloped morphology, while the Cu3Sn always grew as a somewhat undulated planar layer in phase with the Cu6Sn5. The Cu6Sn5 layer began to transform from scallop shape to planar type after aging for 375 hours due to reduction in the interfacial energy. The intermetallic layers showed a linear dependence on the square root of aging time. The growth rate constant of the intermetallic compounds are estimated as 15.2 x 10 - 14 and 0.152 x 10 -14 cm 2 /s for Cu6Sn5 and Cu3Sn intermetallic, respectively.
The composite polymer films of polyvinyl alcohol/polypyrrole/chloral hydrate (PVA-PPy-CH) had been prepared. Effects of γ-rays on the electrical conductivity of the composite polymer films had been investigated by using Inductance Capacitance Resistance meter (LCR) meter at a frequency ranging from 20 Hz to 1 MHz. With the incorporation of chloral hydrate in the polymer sample, the conductivity increased indicates that it is capable to be used as dopant for polymerizing conjugated polymer. The electrical conductivity obtained increased as the dose increased, which is in the order of 10-5 Scm-1 indicates that γ-rays is capable to enhance the electrical conductivity of the composite polymer films. The parameter of s is in the range of 0.31 d s d 0.49 and obeyed simple power law dispersion ωs. The Scanning Electron Microscopy (SEM) micrographs reveal the formation of polypyrrole globules in polyvinyl alcohol matrix which increased as the irradiation dose was increased.
Ceramic foams are a class of high porosity materials that are used or being considered for a wide range of technological applications. Ceramic foam was produce by polymer replication method. In this process, commercial polymeric sponge was use as template, dipping with ceramic particles slurry, drying and then sintered to yield a replica of the original foams. The study was focus on the fabrication of different density of ceramic foams by varying the density of ceramic slurries (1.1876, 1.2687, 1.3653 and 1.5295 g/cm3). Properties of ceramic foam produced such as density was characterized accordingly to ASTM C 271-94 and porosity were characterized using Archimedes methods. Compressive and bending strength was performed accordingly to ASTM C1161-94 and C773-88 (1999), respectively. The morphological study was performed using Scanning Electron Microscopy (SEM) and EDX. Density of ceramic foams produced was about 0.5588 and 1.1852 g/cm3, where as porosity was around 26.28 and 70.59 %. Compressive and bending strength was increase from strength also increases from 2.60 to 23.07 MPa and 1.20 to 11.10 MPa, respectively, with increasing of slurries density from 1.1876 to 1.3653 g/cm3. The SEM micrographs show that the cells structure become denser as the slurries density increased. EDX proved that the ceramic used is porcelain. As a conclusion, increasing in slurries density produced ceramic foams with good mechanical properties such as compressive and bending strength and denser body.
Al/B4C composites with 0 wt.%, 5 wt.% and 10 wt.% of B4C were prepared by powder metallurgy and their properties were characterised successfully. Investigation of the effect of milling times (4, 8, 12, 16 hours) on microstructure, phase identification, hardness and neutron attenuation coefficient of composites has been studied. The results showed that hardness increased with increased of milling time, with maximum hardness obtained at 16 hours milling time. The increment is slower as the composition of B4C increased. The hardness of Al/10%B4C, Al/5%B4C and Al/0%B4C were 81.7, 78.7 and 61.2 HRB respectively. Morphology of scanning electron microscopy (SEM) showed that microstructures play important role in controlling the hardness. Meanwhile, x-ray diffraction (XRD) analysis showed the phases and crystalline present in composites with an indication that crystalline of the grain increased as the milling time increased. Neutron absorption of Al/10%B4C composites showed that this composite has the highest attenuation coefficient, thus indicating that it is the best composites for neutron shielding.
The composite polymer films of polyvinyl alcohol/polypyrrole/chloral hydrate (PVA-PPy-CH) had been prepared. Effects of J-rays on the electrical conductivity of the composite polymer films had
been investigated by using Inductance Capacitance Resistance meter (LCR) meter at a frequency
ranging from 20 Hz to 1 MHz. With the incorporation of chloral hydrate in the polymer sample, the conductivity increased indicates that it is capable to be used as dopant for polymerizing conjugated polymer. The electrical conductivity obtained increased as the dose increased, which is in the order of 10-5Scm-1 indicates that J-rays is capable to enhance the electrical conductivity of the composite polymer films. The parameter of s is in the range of 0.31 d s d 0.49 and obeyed simple power law dispersion Zs. The Scanning Electron Microscopy (SEM) micrographs reveal the formation of polypyrrole globules in polyvinyl alcohol matrix which increased as the irradiation dose was increased.
The experiment aims to investigate the effect of high energy milling to the crystallite size of α-alumina. The starting material used is α-alumina powder with starting crystal size of 86nm. This powder was milled at different time ranges from 0 to 60 minutes and milling speed ranges from 400 rpm to 1100 rpm using a wet milling technique in corundum abrasive materials. The wet milling technique involved the use of water with the alumina to water ratio of 1:6.1. Samples prepared were then examined using the X-Ray Diffraction (XRD) to calculate the crystallite size and scanning electron microscope (SEM) was also used to determine changes in the morphology. Results from these analysis showed that the crystallite size will get smaller when milling speed and time of more than 600rpm and 30 minutes respectively were used. Optimum conditions to achieve the smallest crystal size of 79.7nm are 1000 rpm and 60 minutes.
This paper presents a study on the effect of Arenga Pinnata fibre volume fraction on the tensile and compressive properties of Arenga Pinnata fibre reinforced epoxy composite (APREC). The composites were produced using four different Arenga Pinnata fibre volume contents, which were 10vol%, 15vol%, 20vol%, and 25vol%, in unidirectional (UD) fibre alignment. Tensile and compression tests were performed on all APREC specimens in order to investigate the effect of fibre volume fraction on modulus of elasticity, strength and strain to failure. The morphological structure of fractured specimens was observed using scanning electron microscopy (SEM) in order to evaluate the fracture mechanisms involved when the specimens were subjected to tensile or compressive loading. The results indicated that the higher the amount of Arenga Pinnata fibres, the higher the stiffness of the composites. This is shown by the increment of tensile and compressive modulus of the specimens when the fibre volume content was increased. Tensile modulus increased up to 180% when 25vol% Arenga Pinnata fibre was used in APREC compared to Pure Epoxy specimen. It can also be observed that the tensile strength of the specimens increased 28% from 53.820 MPa (for Pure Epoxy) to 68.692 MPa (for Epoxy with 25vol% APREC addition). Meanwhile, compressive modulus and strength increased up to 3.24% and 9.17%, respectively. These results suggest that the addition of Arenga Pinnata fibres significantly improved the tensile and compressive properties of APREC.
The objective of the study was to asses the adhesion of Streptococcus mutans on nanofilled and microfilled composite resin and glass ionomer cement restorative materials. Glass ionomer cements; KetacTM N100 (nanofilled) and Fuji IITM LC (microfilled) and composite resins; FiltekTM Z350 (nanofilled) and FiltekTM Z250 (microhybrid) were packed in acrylic mould of 2 mm thickness and 5 mm diameter. All samples were light-cured and polished with Sof-Lex discs. All materials were cultured with the exponential phase of S. mutans cultivation. Surface roughness values were assessed using Atomic Force Microscope (AFM, Ambios, USA) at time intervals (7hrs, 24 hrs, 7 days, 14 days and 21 days). The morphology of S. mutans on materials was observed after 24 hour incubation of S. mutan on materials under Scanning Electron Microscope (SEM, Quanta FEG 450). Within groups, results showed that both nanofilled materials had lower surface roughness and less adhesion of S. mutans compared to microfilled materials. This study would enhance the clinical knowledge especially in aesthetic area and improve the longevity of the dental restoration.
Silicon dioxide (SiO2) has been extensively studied due to their unique properties that make it desirable for many applications ranging from electronic, catalysis, pigment as well as sensors. Multitude of methods and processes are established with the ability to manipulate and control the key properties that can cater for specific applications. Stober method is a very simple and easy for up-scale production of SiO2. This paper presents the experimental study on the effect of synthesis parameter on the morphology of SiO2 synthesized via Stober method. Three parameters were investigated such as concentration of catalyst, concentration of precursor and percentage of water content. The obtained samples were characterized using scanning electron microscopy (SEM) analysis. The findings showed that the size of particles produced is dependent on the synthesis parameter. In this study, particles size ranging from 50 nm to >100 nm are easily produced. The sphere size of SiO2 can be increased by increasing the concentration of ammonia hydroxide catalyst, the concentration of TEOS, as well as the percentage of water content.
Melissopalynology (pollen analysis) allows the identification of floral sources, botanical and geographical origin of selected Kelulut honey samples. Therefore, the aim of this study is to determine the origin of selected Kelulut honey by Geniotrigona thoracica and Heterotrigona itama farmed and harvested at Lenggong (Perak). Briefly, the honey was diluted in ddH2O and filtered to obtain the pollens. Subsequently, the morphology of the pollens was observed under scanning electron microscope (SEM) and the frequency classes of species were determined. Based on qualitative and quantitative analysis, G. thoracica honey was demonstrated to be a uni-floral honey and H. Itama honey as a multi-floral honey. A total of 7 types of pollens were observed in G. thoracica honey while 9 types in H. Itama honey. Some of the pollen were identified with the aid of pollen atlas while some were unidentified. Furthermore, the results obtained in this study suggested that the pollens present in Kelulut honey are crucial in identifying botanical resource of stingless bee honey, which assist in preserving the ecosystem.
Data presented in this article focused on the application of Methyl Ester Sulphonate (MES) surfactant and nanopolystyrene in water based drilling fluid. Data from rheology study using Bingham and Power law models showed that the synergy of MES and nanopolystyrene improved the formulated drilling fluid. Filtration study under LPLT and HPHT conditions showed that MES and nanopolystyrene drilling fluid reduced filtration loss by 50.7% at LPLT and 61.1% at HPHT conditions. These filtration data were validated by filter cake permeability and scanning electron microscope images.
This study utilized the incorporation of nanoparticle filler into an epoxy system to study the effect of different nanosized
montmorillonite (MMT) fillers on the thermal stability and mechanical properties of epoxy. The sample was prepared
using diglycidyl ether of bisphenol A (DGEBA) with different surface treatments of montmorillonite filler by mechanical
stirring. The results of thermal stability and mechanical properties of epoxy/clay system obtained from thermal gravimetric
analyzer (TGA), universal testing machine (UTM) and scanning electron microscopy (SEM) were discussed. With the same
amount of filler introduced into the system, different thermal stability of epoxy composite can be observed. Bentonite,
which contained other contaminant components, can downgrade the enhanced properties of the filler.
This article reports on the studies of structural and optical properties of nanoporous GaN prepared by Pt assisted electro chemical etching. The porous GaN samples were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), and optical transmission (OT). SEM images liang indicated that the density of the pores increased with etching duration, however, the etching duration has no significant effect on the size and shape of the pores. AFM measurements exhibited that the surface roughness was increased with etching durations, however, for long etching duration, the increase of the surface roughness became insignificant. OT measurements revealed that the increase of pore density would lead to the reduction of light transmission. The studies showed that the porosity could influence the structural and optical properties of the GaN.