The effect of physical shearing on the attachment of six Pseudomonas aeruginosa strains and six Burkholderia cepacia strains to glass, stainless steel, polystyrene and Teflon® was determined. A significant (p < 0.05) decrease in hydrophobicity was apparent for all P. aeruginosa strains (17-36%) and B. cepacia, MS 5 (20%) after shearing. A significant (p < 0.05) decrease in attachment of some P. aeruginosa (0.2-0.5 log CFU/cm2) and B. cepacia (0.2-0.4 log CFU/cm2) strains to some surface types was apparent after shearing. Significant (p < 0.05) correlation was observed for both numbers of flagellated cells and hydrophobicity against attachment to glass, stainless steel and polystyrene for P. aeruginosa while only hydrophobicity showed significant correlation against the same surfaces for B. cepacia. Scanning electron microscopy and protein analysis showed that shearing removed surface proteins from the cells and may have led to the observed changes in hydrophobicity and attachment to abiotic surfaces.
The photodegradation efficiency of ZnO nanoparticles in removal of organic pollutants deteriorates over time as a high percentage of the nanoparticles can be drained away by water during the wastewater treatment. This problem can be solved by growing the ZnO nanorods on stainless steel wire. In this work, ZnO nanorods were successfully grown on stainless steel wire by chemical vapour deposition. The SAED analysis indicates that ZnO nanorod is a single crystal and is preferentially grown in [0001] direction. The deconvoluted O 1s peak at 531.5 eV in XPS analysis is associated with oxygen deficient, revealing that the ZnO nanorods contain many oxygen vacancies. This observation is further supported by the finding of the small I(uv)/I(vis) ratio, that is, ~1 in the photoluminescence analysis. The growth of ZnO nanorods on stainless steel wire was governed by vapour-solid mechanism as there were no Fe particles observed at the tips of the nanorods. The photodegradation of Rhodamine B solution by ZnO nanorods followed the first-order kinetics.
The present study was conducted to compare the cleaning efficacy (debris and smear layer removal) of hand and two NiTi rotary instrumentation systems (K3 and ProTaper).
Failure analysis was performed to investigate the failure of the femur fixation plate which was previously fixed on the femur of a girl. Radiography, metallography, fractography and mechanical testing were conducted in this study. The results show that the failure was due to the formation of notches on the femur plate. These notches act as stress raisers from where the cracks start to propagate. Finally fracture occurred on the femur plate and subsequently, the plate failed.
In-stent restenosis is caused by the proliferation of the smooth muscle cells (SMCs) following a host response towards the implanted device. However, the precise biochemical and cellular mechanisms are still not completely understood. In this paper, the behaviour of SMCs has been investigated by an in vitro model where the cells were stimulated by platelet derived growth factor (PDGF) on tissue-like substrates as well as on biomaterials such as stainless steel (St) and diamond-like carbon (DLC)-coated St. The results demonstrated that SMCs have a completely different adhesion mode on St and become particularly prone to proliferation and pro-inflammatory cytokine secretion under PDGF stimulus. This would suggest that restenosis may caused by the accidental contact of the SMC with the St substrate under an inflammatory insult.
This research investigates and analyzes wear properties of 316 stainless steel before and after applying paste boronizing process and to investigate the effect of shot blasting process in enhancing boron dispersion into the steel. In order to enhance the boron dispersion into 316 stainless steel, surface deformation method by shot blasting process was deployed. Boronizing treatment was conducted using paste medium for 8 hours under two different temperatures which were 8500 C and 9500 C. Wear behaviour was evaluated using pin-on-disc test for abrasion properties. The analysis on microstructure, X-ray Diffraction (XRD) and density were also carried out before and after applying boronizing treatment. Boronizing process that had been carried out on 316 stainless steel increases the wear resistance of the steel compared to the unboronized 316 stainless steel. The effect of boronizing treatment together with the shot blasting process give a greater impact in increasing the wear resistance of 316 stainless steel. This is mainly because shot blasted samples initiated surface deformation that helped more boron dispersion due to dislocation of atom on the deformed surface. Increasing the boronizing temperature also increases the wear resistance of 316 stainless steel. In industrial application, the usage of the components that have been fabricated using the improved 316 stainless steel can be maximized because repair and replacement of the components can be reduced as a result of improved wear resistance of the 316 stainless steel.
Detection of cracks from stainless steel pipe images is done using contrast stretching technique. The technique is based on an image filter technique through mathematical morphology that can expose the cracks. The cracks are highlighted and noise removal is done efficiently while still retaining the edges. An automated crack detection system with a camera platform has been successfully implemented. We compare crack extraction in terms of quality measures with those of Otsu's threshold technique and the another technique (Iyer and Sinha, 2005). The algorithm shown is able to achieve good results and perform better than these other techniques.
Microbial fuel cells (MFCs) have a high potential application for simultaneous wastewater treatment and electricity
generation. However, the choice of the electrode material and its design is critical and directly affect their performance.
As an electrode of MFCs, the anode material with surface modifications is an attractive strategy to improve the power
output. In this study, stainless steel (SS) and carbon steel (CS) was chosen as a metal anode, while graphite felt (GF)
was used as a common anode. Heat treatment was performed to convert SS, CS and GF into efficient anodes for MFCs.
The maximum current density and power density of the MFC-SS were achieved up till 762.14 mA/m2
and 827.25 mW/m2
,
respectively, which were higher than MFC-CS (641.95 mA/m2
and 260.14 mW/m2
) and MFC-GF (728.30 mA/m2
and 307.89
mW/m2
). Electrochemical impedance spectroscopy of MFC-SS showed better catalytic activity compared to MFC-CS and
MFC-GF anode, also supported by cyclic voltammetry test.
Corrosion caused by sulphate-reducing bacteria (SRB) isolated from seawater nearby to Pasir Gudang has been studied. The test coupon was a AISI 304 stainless steel. Potential and corrosion rate measurements were carried out in various types of culturing solutions, with SRB1, SRB2, combination of SRB1 & SRB2 and without SRBs inoculated (sterilized). From Tafel plots a higher corrosion rate has been found in medium inoculated with SRBs than that of the sterilized medium (control). When SRBs were present in the medium, the Tafel plot shifted towards more negative values (Ecorr was shifted to much less anodic values) and increase in current density compared to that of the sterilized medium (control). Localized corrosion was observed on the metal surface, and it was associated to the SRB activity. X-ray analysis (EDAX) showed that the corrosion product has higher content of sulphur for medium containing SRBs than that of the sterilized medium. X-Ray Diffraction analysis carried out on corrosion products which showed the presence of iron sulphide. This indicates the influence of the presence of SRB in corrosion process.
Acetone-butanol-ethanol (ABE) fermentation from Palm Oil Mill Effluent (POME) by C. acetobutylicum NCIMB 13357 in an oscillatory flow bioreactor was investigated. Experimental works were conducted in a U-shaped stainless steel oscillatory flow bioreactor at oscillation frequency between 0.45-0.78 Hz and a constant amplitude of 12.5 mm. Fermentations were carried out for 72 hr at 35oC using palm oil mill effluent and reinforced clostridia medium as a growth medium in batch culture. Result of this investigation showed that POME is a viable media for ABE fermentation and oscillatory flow bioreactor has an excellent potential as an alternative fermentation device.
Fixed orthodontic treatment requires the use of orthodontic brackets and archwires in order to correct malocclusions. The objective of this study was to evaluate the pattern of orthodontic material usages i.e. bracket and archwire among Malaysian orthodontists. A self-administered questionnaire was distributed to members of the Malaysian Association of Orthodontist. Data entry and statistical analysis was done using SPSS version 15.0. Descriptive statistics were used for analysis. Means and standard deviations were calculated for continuous variables, frequency and percentages for categorical variables. Thirty-four orthodontists responded to the survey, with 76% (n=26) were female and the mean age was 43.31 years (SD 8.76). Most respondents used conventional metal brackets (60%, n=60) and most bracket prescription used was MBT (56%, n=19). At levelling stage, most respondents used nickel titanium archwire (84.5%, n=47). Stainless steel archwire was the most favourable choice for retraction/space closure stage (73.9%, n=34). At finishing, most respondents (60.4%, n=29) preferred to use stainless steel wire in their cases. As a conclusion, specific types of orthodontic materials were preferred and used by Malaysian orthodontists in delivering orthodontic treatment.
The corrosion potential of AISI 304 stainless steel coupons influenced by sulphate-reducing bacteria (SRB) has been studied. Pure colony of SRB was isolated from the Malaysia Marine and Heavy Engineering, Pasir Gudang, Johor. Open circuit potential measurements were carried out in variable types of culturing solutions with SRB1, SRB2, combination of SRB1 & SRB2 and without SRBs inoculated. Results showed that the corrosion potential, Eoc increased in the presence of SRBs (in pure and mixed culture) compared to that of control. EDS analysis showed the strong peak of sulphur in coupon containing SRB cultures compared to the control. ESEM data showed that the high density cell of SRBs were associated with corroding sections of surface steel comparing with non-corroding sections for coupons immersed in VMNI medium containing SRBs.
In this study, injection molding parameters, including green strength, surface quality and green part density, were optimized using the L18 Taguchi orthogonal array. The L25 Taguchi method was used to optimize the green density of solvent debinding parameters. The feedstock consisted of stainless steel powder (SS316L), with powder loading fractions of 63, 63.5 and 64 v/o. The binder compositions used in the study were polyethelene glycol (PEG-73 wt. %), polymethyl methacrilate (PMMA-25 wt. %) and stearic acid (2 wt. %). The Taguchi method was used to optimize the injection parameters. The obtained optimum parameters were as follows: mold temperature of 65oC, injection temperature of 145oC, injection pressure of 650 bar, injection flow rate of 20 m3/s, holding time of 5 s and powder loading of 64% v/o. Analysis of variance results showed that mold temperature has the greatest influence in the production of good green part surface quality and that powder loading gave the best green part strength. Immersion time and temperature were used to optimize for solvent debinding parameters. By optimizing the solvent debinding parameters, an immersion temperature of 61oC and immersion time of 5 h produced the highest density which is the optimum value gain in this study.
Austenitic stainless steels of grade 304 were exposed to dry (Ar-75%CO2) and wet (Ar-75%CO2-12%H2O) environments at 700oC. This experimental setup involved horizontal tube furnace connected to CO2 gas and water vapour facilities. X-ray diffraction (XRD) technique, variable pressure-scanning electron microscope (VP-SEM) and optical microscope techniques were used to characterize the products of corrosion. The results of XRD showed that the phase of oxide layers consists of Cr2O3 and NiCr2O4 in dry CO2, meanwhile Fe2O3, Cr2O3, Fe0.56Ni0.34, Fe3O4 were identified in wet condition after 50 h. Adding 12%H2O in Ar-75%CO2 leads significantly in weight change occurred at 10 h exposure. However, after 20 h, the weight gain was decreased due to spallation of the oxide scale. The addition of water vapour accelerates the oxidation rate on the steel than that in dry condition. Morphologies and growth kinetics of these oxides vary with reaction condition. The oxidation behaviour at different times of exposure and the effect of water vapour were discussed in correlation with the microstructure of the oxides.
The emission of Extreme Ultra Violet (EUV) from plasma produced by vacuum spark discharge using stainless steel as anode material was investigated. The operating pressure for all the experiments carried out was maintained at below 10-4 mbar. The discharge voltage tested was from 8 kV to 20 kV. The inter-electrode distance suitable for high intensity and reproducible EUV emissions was found to be in the range of 2.6 mm to 4.6 mm. The output EUV energy scaled as ~ V02, where V0 is the discharge voltage.
Three different designs of heat exchanger, V-groove, honeycomb and stainless steel wool had been tested to study their effectiveness in improving the overall performance of a photovoltaic/thermal (PV/T) air base solar collector. Heat exchangers were installed horizontally into the channel located at the back side of the PV module. The system was tested at irradiance of 828 W/m2 with mass flow rate spanning from 0.02 kg/s to 0.13 kg/s. It was observed that at mass flow rate of 0.11 kg/s, the maximum thermal efficiency of the system with V-groove is 71%, stainless steel wool is 86% and honeycomb is 87%. The electrical efficiency of the systems is 7.04%, 6.88% and 7.13%, respectively. The experimental results showed that honeycomb design is the most efficient design as heat exchanger. The design which is simple and compact is suitable for building integration.
The aim of this study was to investigate the simultaneous influence of various dental posts and cementation materials on the fracture resistance and failure mode of the endodontically-treated teeth. Sixty endodontically treated upper central incisors were randomly divided into two main groups, each consisted of three subgroups restored with titanium, fiber and stainless steel posts. The posts in the first and second groups were luted with zinc phosphate and composite resin cements, respectively. Composite cores were built-up over the specimens and then retained with nickel-chromium crowns. Specimens were thermocycled and then loaded at 135o until failures were observed. The obtained data of fracture resistances and failure modes were analyzed using Two-way ANOVA and the Chi-Square tests, respectively. The results showed that the zinc phosphate cement resulted in relatively higher fracture resistances. However, luting of dental posts with composite resin provided more restorable failures in endodontically-treated teeth. Moreover, the teeth restored by fiber posts exhibited desirable fracture resistances with more restorable failure modes, compared with those restored by titanium or stainless steel posts.
In this study, two nickel based electrodes were prepared; nickel foil and nickel-polyvinylchloride (Ni-PVC), in order to study their electrochemical behavior using cyclic voltammetry, CV and chronocoulometry, CC. Ni electrode was prepared from Ni metal foil while Ni-PVC electrode was prepared by mixing a weighed portion of Ni powder and PVC in THF solvent, swirled until the suspension was homogeneous and drying the suspension in an oven at 50oC for 3 h. The dry sample was then placed in a 1 cm diameter stainless steel mould and pressed at 10 ton/cm2. From CV data, Ni-PVC electrode showed a better electrochemical behavior compared to Ni metal foil electrode. The use of Ni-PVC electrode at higher concentration of supporting electrolyte (1.0 M KOH) was better than at lower concentration of the same supporting electrolyte in electroxidation of ethanol. In addition to acetic acid, the oxidation of ethanol also produced ethyl acetate and acetaldehyde.