Weld cladding is a process for producing surfaces with good corrosion resistant properties by means of depositing/laying of stainless steels on low-carbon steel components with an objective of achieving maximum economy and enhanced life. The aim of the work presented here was to investigate the effect of auxiliary preheating of the solid filler wire in mechanized gas metal arc welding (GMAW) process (by using a specially designed torch to preheat the filler wire independently, before its emergence from the torch) on the quality of the as-welded single layer stainless steel overlays. External preheating of the filler wire resulted in greater contribution of arc energy by resistive heating due to which significant drop in the main welding current values and hence low dilution levels were observed. Metallurgical aspects of the as welded overlays such as chemistry, ferrite content, and modes of solidification were studied to evaluate their suitability for service and it was found that claddings obtained through the preheating arrangement, besides higher ferrite content, possessed higher content of chromium, nickel, and molybdenum and lower content of carbon as compared to conventional GMAW claddings, thereby giving overlays with superior mechanical and corrosion resistance properties. The findings of this study not only establish the technical superiority of the new process, but also, owing to its productivity-enhanced features, justify its use for low-cost surfacing applications.

Laser welding will be  an important welding process for different applications in aerospace , aircraft , automotive, electronics  and other industries, due to its capabilities like minimum heat affected zone, welding of various thicknesses, adoptability to welding of various materials possessing widely varying physical properties like melting point, absorption, reflectivity etc. It utilizes laser source as a non contact heat generation technology to weld different materials so as to achieve welds of high quality narrow width and high penetration depths without the need of filler wires. It may be necessary to understand the effect of process parameters on the weldability of materials for successful welding. Laser welding popularly uses two types of lasers like CO2 and Nd:YAG (neodymium doped yttrium – aluminium – garnet)  with different powers. Nd:YAG lasers are used to weld materials of different thicknesses involving powers upto 5 kW. Whereas, CO2 lasers are used for applications which involve higher powers upto 20 kW. Laser welding allows a direct transition from light energy into heat energy. This technique is involved with the process of laser - matter interaction in which various parameters such as pulse energy, pulse duration, spot size, welding speed, laser power, weld width, penetration depth, reflectivity, absorption coefficient, thermodynamic properties etc. are used for analysis. This paper presents a review of the different parameters including process as well as materials on the weldability of various materials like carbon steels, stainless steels, magnesium alloys, aluminium alloys, refractory materials such as vanadium, titanium, zirconium, tantalum etc. The selection of appropriate parameter for welding of specified material is discussed. The prominent weld defects common to the laser welding such as porosity, oxide inclusions, cracking, loss of alloying elements etc., are discussed as related to the microstructure as well as mechanical properties such as hardness, tensile strength and fatigue strength etc.

The purpose of this 2-part opinion article was to project the developments expected to occur in the next few years in orthodontic materials research and applications. Part 1 reviewed developments in bonding to enamel. Part 2 looks at other orthodontic materials applications and explores emerging research strategies for probing the biological properties of materials. In the field of metallic brackets, expansion of the use of titanium alloys with improved hardness and nickel-free steels with better corrosion resistance and increased hardness is expected. Manufacturing techniques might be modified to include laser-welding methods and metal injection molding. Esthetic bracket research will involve the synthesis of high-crystallinity biomedical polymers with increased hardness and stiffness, decreased water sorption, and improved resistance to degradation. New plastic brackets might incorportate ceramic wings. Fiber-reinforced composite archwires, currently experimental, could soon be commercially available, and long-term applications of shape-memory plastics might become viable. Advancements in elastomeric materials will result in polymers with reduced relaxation, broader use of fluoride-releasing elastomers with decreased relaxation, and large-scale film coating of elastomers to decrease reactivity, water sorption, and degradation. Finally, biocompatibility assessments will incorporate testing of potential endocrinological action. New polymer formulations might be tested in adhesive and plastic bracket manufacturing, based on benzoic ring-free monomers to avoid the adverse effects of the estrogenic molecule bisphenol-A. (Am J Orthod Dentofacial Orthop 2007;131:253-62) T he second part of this article includes a review of the current status of brackets, elastomerics, and archwires along with a projection of future developments in materials technology and clinical applications. It also gives a brief description of the novel assessment of the biological properties of polymers, which have already been implemented in associated biomedical disciplines.

A conceptually new structural design approach has recently been proposed by the authors to predict the resistance of stainless steel members subjected to various types of loading with cross-sections formed from thin flat plates including angles, channels, lipped channels, I-sections and rectangular hollow sections (RHS). The proposed method does not follow the traditional cross-section classification approach, which primarily relies on the assumption of a bilinear, elastic-perfectly-plastic material model. Instead, deformation capacity of a cross-section is determined directly from the local buckling characteristics of the constituent plate elements. This is then used to obtain the corresponding local buckling stress utilising an appropriate material model. This basic concept is extended herein to predict compression resistance of stainless steel columns with circular hollow sections (CHS). Available test and finite element (FE) results have been used to develop the basic design equation to predict the compression resistance of cross-sections and to propose column curves to determine flexural buckling resistances. The predicted resistances have been compared to those obtained using the current Eurocode; the predictions are significantly more accurate and more consistent than those given by the existing Eurocode.

The paper describes the test results of an ongoing major European research project which is concerned with the further development and refinement of structural design guidance for stainless steel. The paper concentrates on the work carried out to date on the design of beams, columns and beam-columns and compares the test results with resistances predicted by the design pre-standard for structural stainless steel, ENV 1993-1-4. In general, the design guidance is conservative. The tests on CHS beams indicate that the limiting diameter-to-thickness ratios for section classification can be considerably increased. For welded I-section beams, the ENV 1993-1-4 lateral torsional buckling curve appears very conservative and the less conservative curve adopted in ENV 1993-1-1 for carbon steel appears to give a better fit to the data.

As the structure of biofilms plays a key role in their resistance and persistence, this work presents for the first time the numerical characterization of the temporal evolution of biofilm structures formed by three Listeria monocytogenes strains on two types of stainless-steel supports, AISI 304 SS No. 2B and AISI 316 SS No. 2R. Counting methods, motility tests, fluorescence microscopy and image analysis were combined to study the dynamic evolution of biofilm formation and structure. Image analysis was performed with several well-known parameters as well as a newly defined parameter to quantify spatio-temporal distribution. The results confirm the interstrain variability of L. monocytogenes species regarding to biofilm structure and structural evolution. Two types of biofilm were observed: homogeneous or flat and heterogeneous or clustered. Differences in clusters and in attachment and detachment processes were due mainly to the topography and composition of the two surfaces although an effect due to motility was also found.

The creep properties of a nuclear-grade type 316 (L) stainless steel (SS) alloyed with nitrogen (316L (N) SS) and its weld metal were studied at 873 and 923 K in the range of applied stresses from 100 to 335 MPa. The results were compared with those obtained on ...

Type 316L stainless steel (316L SS), commonly used as pot roll material, was tested in an industrial Zn-Al galvanizing bath, with an effective Al content of 0.2 wt.%. Samples welded to the supporting roll arms and sides of the sink roll experienced heavy dross buildup. Samples placed at locations away from the incoming strip generally experienced much less dross buildup. Dross particles within the buildup on samples attached to supporting roll arms were small in size but numerous while particles on samples welded to the sides of the sink roll were much larger. SEM-EDS analyses indicated that the buildup consisted of two layers. The inner layer was the product of the corrosive reaction of 316L SS with the bath metal, and the outer layer was formed by dross particles built up on the inner reaction layer. The intermetallic phase, which formed at the reaction front of the samples was the inhibition compound Fe 2 Al 5 containing some Mo and Cr. The formation of this intermetallic layer provided a thermodynamically favourable base for the attachment and further buildup of suspended dross particles on the sample surfaces.

One of the current challenges for application of PEM fuel cell is to find corrosion resistant, electrically conductive, light weight, cost competitive bipolar plate material. Low temperature carburization (LTC) of stainless steels is a novel, patented process by Swagelok Company. This paper addresses the corrosion resistance characteristics of LTC SS 316 for polymer electrolyte membrane fuel cell (PEMFC) bipolar plate applications. Corrosion properties of this material were studied using potentiodynamic and potentiostatic tests in simulated (1 M H 2 SO 4 + 2 ppm HF, 0.5 M H 2 SO 4 , pH: 4.0, and 5% HCl + 5% Na 2 SO 4) PEMFC conditions. LTC SS 316 showed excellent corrosion resistance in these conditions compared to SS 316. The mechanism of anodic dissolution and general corrosion of LTC SS 316 was observed to be similar to SS 316 however the extent of LTC SS 316 corrosion was less. LTC SS 316 showed corrosion currents well below 16 A cm −2 in anodic and cathodic atmospheres under potentiostatic conditions. The potentiostatic current rapidly falls to ∼4.0 and ∼1.5 A cm −2 under anodic and cathodic conditions, respectively. LTC SS 316 was observed to form a thinner oxide layer as compared to SS 316 after 24 h of potentiostatic testing. Moreover LTC SS 316 lowered the interfacial contact resistance by approximately 24% as compared to SS 316 after corrosion testing. Hence this study clearly states the performance advantage of using LTC SS 316 as bipolar plate material as compared to conventional materials.

The cyclic mechanical behaviour during thermal fatigue of a martensitic stainless steel (MANET I) is investigated and correlated with its microstructure. The tests were performed in air by allowing the sample to serve as its own heater and converting any longitudinal thermal deformation of the specimen into elastic or inelastic deformation. The effects of different thermal cycling ranges and the imposition of several hold-time conditions on the mechanical behaviour and the accompanying microstructural changes in the specimen were evaluated. A continuous softening is the characteristic feature observed in all thermal fatigue tests. Higher mean temperatures, larger temperature changes and the application of temperature-hold periods produce an accelerated softening process. All temperature hold-time conditions influence the mechanical behaviour, reducing the number of cycles to failure. The initial tempered martensite lath structure evolves to a mixed structure of expanded laths and subgrains or a fully subgrain structure, depending on the mean temperature, the temperature change and the temperature at which the hold period has been applied. Tests with temperature holds at higher temperatures show more deleterious effects than tests with hold-times at lower temperatures. NOMENCLATURE HTL = test with hold time at low temperature HTH = test with hold time at high temperature HTHL=test with hold time at high and low temperature no HT= test without hold time N = number of cycles Nf= number of cycles to failure T = temperature TL=low temperature of the test TH= high temperature of the test ALz = axial deflection range AT_= TH-TL T= mean temperature = (TH/2)+(TL/2) E = normal strain u = normal stress uc =compressive peak stress uT= tensile peak stress Cr = mean stress Au = stress range, uTuc Auc = additional stress imposed in compression during the hold time Au,= additional stress imposed in tension during the hold time

In this paper the production of laccase and the decolouration of the recalcitrant diazo dye Reactive Black 5 (RB5) by the white-rot fungus Trametes pubescens immobilised on stainless steel sponges in a fixed-bed reactor were studied. Laccase production was increased by 10-fold in the presence of RB5 and reached a maximum value of 1025 U/l. Enhanced laccase production in the presence of RB5 in this fungus is an added advantage during biodegradation of RB5-containing effluents. The decolouration of RB5 was due to two processes: dye adsorption onto the fungal mycelium and dye degradation by the laccase enzymes produced by the fungus. RB5 decolouration was performed during four successive batches obtaining high decolouration percentages (74%, 43% and 52% in 24 h for the first, third and four batch, respectively) without addition of redox mediators. Also, the in vitro decolouration of RB5 by the concentrated culture extract, containing mainly laccase, produced in the above bioreactor was studied. The decolouration percentages obtained were considerably lower (around 20% in 24 h) than that attained with the whole culture.

Various accelerated cabinet tests have been used for the evaluation of the cut-edge corrosion of coil-coated architectural cladding. These include the conventional ASTM B-117 method (5% continuous NaCl spray), the standard Prohesion test (0.35% (NH 4 ) 2 SO 4 0.05% NaCl wet/dry spray) as well as modi®ed wet/dry spray tests using a relatively dilute arti®cial acid rain solution, shallow specimen incline angles with variations in the ratio of the wet and dry periods. Comparisons with outdoor exposure samples reveal that the B-117 test shows unrealistic corrosion morphology with the most realistic cut-edge corrosion given by the modi®ed tests. Furthermore, with all types of wet/ dry test specimen-to-specimen variation is considerably reduced compared with the continuous salt spray test. In the novel wet-dry tests the acceleration factor appears consistent with the number of wet and dry cycles however, the overall acceleration factor is limited and, hence, test times are extended. It is concluded that, over a 1000 h test time, the standard Prohesion test appears to show the best combination of realism and acceleration. # 0300-9440/99/$ ± see front matter # 1999 Elsevier Science S.A. All rights reserved. PII: S 0 3 0 0 -9 4 4 0 ( 9 8 ) 0 0 0 4 8 -4

The corrosion resistance of a two-layer polymer (silane + parylene) coating, on implant stainless steel was investigated by microscopic observations and electrochemical measurements. Long term exposure tests in Hanks solution revealed that the coating of 2 lm can be successfully used for corrosion protection. However, the addition of H 2 O 2 , simulating the inflammatory response of human body environment causes a dramatic destruction of the protective coating. Analysis of the experimental data in terms of circuit models enables proposing a deterioration mechanism. OH Å radicals formed at the metal surface attack the polymer, thus the deterioration starts from the metal/polymer interface and progress towards the outward surface.

The application of computational fluid dynamics (CFDs) in the area of porous media and adsorption cooling system is becoming more practical due to the significant improvement in computer power. The results from previous studies have shown that CFD can be useful tool for predicting the water vapour flow pattern, temperature, heat transfer and flow velocity and adsorption rate. This paper investigates the effect of silica gel granular size on the water adsorption rate using computational fluid dynamics and gravimetric experimental (TGA) method.

Bone remodeling due to stress-shielding has been studied using a model system consisting of metal-polymer laminated fixation plates securely fixed to canine femurs. The plate stiffness was controlled by varying the ratio of metal facing to polymer core thickness in the laminate design while secure fixation to bone was achieved by providing a porous bone interfacing surface for the ingrowth of bone from the periosteal sur-face. Observations of laterally and medially placed plates indicated resorption in the area of the periosteal and endosteal bone surfaces respectively, for the higher stiffness composite plates used. The results indicate that plate stiffness greater than approximately 70 GPa (axial) and 6 N m2 (flexural) will result in extensive bone remodeling in the canine femur after a six month implantation period.

Tungsten nitride (WN) films were deposited on the stainless steel-304 substrate by a 2 kJ Mather-type plasma focus device. The preparation method and characterization data are presented. X-ray diffractometer (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed for the characterization of the samples obtained with different number of focus shots, respectively. The average size of crystallites (from XRD), sub-micro-structures (from SEM) and particles (from AFM images) increase when the number of shots increase from 10 to 20 then 30, then they decrease when the substrate is exposed to 40 shots.

AISI 316 austenitic stainless steels have been plasma nitrided using a dc glow discharge unit in order to investigate the influence of gas composition on microstructure and corrosion behavior of treated samples. Corrosion properties of untreated and plasma nitrided 316 steels ...

Background: The aim of this study is to evaluate the mechanical properties of the screws used for rapid expansion of the upper jaw. Methods: Ten types of expansion screw were assessed, seven with four arms: Lancer Philosophy 1, Dentaurum Hyrax Click Medium, Forestadent Anatomic Expander type "S", Forestadent Anatomic Expander type "S" for narrow palates, Forestadent Memory, Leone A 2620-10 with telescopic guide, and Leone A 0630-10 with orthogonal arms; and three with two arms: Dentaurum Variety S.P., Target Baby REP Veltri, and Leone A 362113. A test expander with the mean dimensions taken from measurements on a sample of 100 expanders was constructed for each screw. The test expanders were connected to the supports of an Instron 4467 (Instron Corp., USA) mechanical testing machine equipped with a 500 N load cell, and the compression force exerted after each activation was measured. The mean forces expressed by the two-and four-arm expanders were then compared. Results: After five activations, the forces expressed by the two-arm devices were double than those expressed by the four-arm devices on average (224 ± 59.9 N vs. 103 ± 32.9 N), and such values remained high after subsequent activations. Conclusions: The expanders tested demonstrated stiffness characteristics compatible with opening of the palatine sutures in pre-adolescent patients. The stiffness of such devices can be further increased during the construction phase.

Due to the relatively high activity concentrations of 210 Po and 210 Pb that are found in tobacco and its products, cigarette smoking highly increases the internal intake of both radionuclides and their concentrations in the lung tissues. That might contribute significantly to an increase in the internal radiation dose and in the number of instances of lung cancer observed among smokers. Samples of most frequently smoked fine and popular brands of cigarettes were collected from those available on the Egyptian market. 210 Po activity concentrations were measured by alpha spectrometry, using surface barrier detectors, following the radiochemical separation of polonium. Samples of fresh tobacco, wrapping paper, fresh filters, ash and postsmoking filters were spiked with 208 Po for chemical recovery calculation. The samples were dissolved using mineral acids (HNO 3 , HCl and HF). Polonium was spontaneously plated-out on stainless steel disks from diluted HCl solution. The 210 Po activity concentration in smoke was estimated on the basis of its activity in fresh tobacco and wrapping paper, fresh filter, ash and post-smoking filters. The percentages of 210 Po activity concentrations that were recovered from the cigarette tobacco to ash, post-smoking filters, and smokes were assessed. The results of this work indicate that the average (range) activity concentration of 210 Po in cigarette tobacco was 16.6 (9.7-22.5) mBq/cigarette. The average percentages of 210 Po content in fresh tobacco plus wrapping paper that were recovered by post-smoking filters, ash and smoke were 4.6, 20.7 and 74.7, respectively. Cigarette smokers, who are smoking one pack (20 cigarettes) per day, are inhaling on average 123 mBq/d of 210 Po and 210 Pb each. The annual effective doses were calculated on the basis of 210 Po and 210 Pb intake with the cigarette smoke. The mean values of the annual effective dose for smokers (one pack per day) were estimated to be 193 and 251 µSv from 210 Po and 210 Pb, respectively.

This study describes the use of electrodeposited nanostructured hybrid nickel–cobalt hexacyanoferrate in electrochemical supercapacitors. Herein, various compositions of nickel and cobalt hexacyanoferrates (Ni/CoHCNFe) nanostructures are electrodeposited on an inexpensive stainless steel substrate using cyclic voltammetric (CV) method. The morphology of the electrodeposited nanostructures is studied using scanning electron microscopy, while their electrochemical characterizations are investigated using CV, galvanostatic charge and discharge and electrochemical impedance spectroscopy. The results show that the nanostructures of hybrid metal cyanoferrate, shows a much higher capacitance (765 F g−1) than those obtained with just nickel hexacyanoferrate (379 F g−1) or cobalt hexacyanoferrate (277 F g−1). Electrochemical impedance spectroscopy results confirm the favorable capacitive behavior of the electrodeposited materials. The columbic efficiency is approximately 95% based on the charge and discharge experiments. Long cycle-life and excellent stability of the nanostructured materials are also demonstrated during 1000 cycles.► Nanostructured hybrid nickel–cobalt hexacyanoferrate is used in supercapacitors. ► A high capacitance (765 F g−1) is obtained at a specific current of 0.2 A g−1. ► Long cycle-life and excellent stability are demonstrated during 1000 cycles.

A v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / h e i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 3 6 ( 2 0 1 1 ) 8 6 4 1 e8 6 4 4

Oxidation of Type 293 and 329 stainless steels for up to 0 h was studied at 0162 K and the composition and structure of the oxide were determined by X!ray photoelectron spectroscopy "XPS# and X!ray di}raction "XRD#[ In the initial several tens of seconds\ only iron!rich corundum!type oxide was formed\ whereas the _nal oxide was composed of an inner chromium!rich corundum!type oxide layer and an outer mixed layer of corundum! type and spinel!type oxides[ An iron!rich metallic a phase was observed on Type 293 stainless steel[ This suggests a growth mechanism where corundum!type oxide on Type 293 stainless steel repeats cycles of breakage and curing of the oxide\ resulting in the formation of metallic a phase in the oxide layer[ A similar reaction is postulated to take place in the oxidation of Type 329 stainless steel[ Þ 0887 Elsevier Science Ltd[ All rights reserved

The present study describes citric acid fermentation by Aspergillus niger GCB-47 in a 15-l stainless steel stirred fermentor. Among the alcohols tested as stimulating agents, 1.0% (v/v) methanol was found to give maximum amount of anhydrous citric acid (90:02 AE 2:2 g/l), 24 h after inoculation. This yield of citric acid was 1.96 fold higher than the control. Methanol has a direct effect on mycelial morphology and it promotes pellet formation. It also increases the cell membrane permeability to provoke more citric acid excretion from the mycelial cells. The sugar consumed and % citric acid was 108 AE 3:8 g/l and 80:39 AE 4:5%, respectively. The desirable mycelial morphology was in the form of small round pellets having dry cell mass 14:5 AE 0:8 g/l. Addition of ethanol, however, did not found to enhance citric acid production, significantly. The maximum value of Y p=x (i.e., 5:825 AE 0:25 g/g) was observed when methanol was used as a stimulating agent. The best results of anhydrous citric acid were observed, 6 days after inoculation when the initial pH of fermentation medium was kept at 6.0.

The conductance and electrostriction of bilayer lipid membranes (sBLM) supported on stainless steel and on conducting polymer polypyrrole (PPY) were studied. We showed that an increase in ammonia concentration resulted in an increase in d.c. current flow across the PPY layer adjacent to the metal surface and that covered by the lipid bilayer. The elasticity modulus in the direction perpendicular to the sBLM surface (E) and the electrical capacitance (C) were characterized by a complicated dependence on the application of an external d.c. voltage. In the case of sBLM formed on the PPY layer and that modified by avidin-urease, higher values of E were observed and in addition the latter system was characterized by a less expressed hysteresis of E and C than the metal supported sBLM. This is evidence that sBLM formed on PPY layers is smoother and more homogeneous than that formed on a metal support. We developed a urea minisensor based on sBLM supported on a PPY layer. Avidin-biotin tec...

Purpose: To assess selected balloon-expandable and selfexpanding stents for radial /brce, flexibility, radio-opacity, and trackability, and to relate these physical characteristics to potential indications for placement. Methods: Force-strain curves were plotted for each stent and the force required to produce 50% luminal narrowing was recorded. The ability of the stent to show elastic recoil following deformation was also noted. Flexibility was measured by bending the stents against a force transducer and recording the force required per degree of flexion. Radioopacity was measured by comparing each stent against a standard aluminum step wedge. Trackability was measured by testing the ability of the stent on its delivery system to track over angles of 90 ~ and 60 ~ . Results: The balloon-expandable stents showed greater radial strength and radio-opacity but, apart from the AVE Iliac Bridge stent, showed poorer flexibility and trackability. The self-expanding stents showed less radial force but were able to re-expand following deformity. They were generally more flexible and had better trackability but lower radio-opacity. Conclusion: There is no stent which exhibits all the ideal properties required and therefore the interventionist will need to keep a range of stents available if all lesions are to be addressed.

Direct Metal Laser Re-Melting is a variant of the Selective Laser Sintering process, a Rapid Prototyping (RP) technology. This tool-less manufacturing technology has the potential of producing complex, high quality components from single-phase metal powders in short time scales. This is made possible by the production of consecutive two-dimensional layers. Unfortunately, finished components manufactured by this technique have their integrity

The irradiation response of PH13-8Mo stainless steel was measured up to 2.5 dpa at 200 and 300°C irradiation temperatures. The PH13-8Mo, a martensitic precipitation-hardened steel, was produced by Hot Isostatic Pressing at 1030°C. The fatigue tests (high cycle fatigue and fatigue crack propagation) showed a test temperature dependency but no irradiation effects. Tensile tests showed irradiation hardening (yield stress increase) of approximately 37% for 200°C irradiated material tested at 60°C and approximately 32% for 300°C irradiated material tested at 60°C. This contradicts the shift in reference temperature (T 0) measured in toughness tests (Master Curve approach), where the DT 0 for 300°C irradiated is approximately 170°C and the DT 0 for the 200°C irradiated is approximately 160°C. This means that the irradiation hardening of PH13-8Mo steel is not suitable to predict the shift in the reference temperature for the Master Curve approach.

This paper is meant to present the mechanical characteristics of austenitic stainless steel rebars under monotonic and cyclic loadings. Furthermore, some results concerning the experimental tests on column prototypes subjected to cyclic loadings are presented, with the intent of comparing with results obtained on analogous columns reinforced with standard high ductile carbon steel rebars.

Chloride ion penetration into concrete and the resulting deterioration (cracking and spalling due to the corrosion of reinforcement) is a major concern of engineers and owners of bridges and marine structures. Several publications have reported the excellent performance of concrete containing alternative cementitious materials (ACMs), such as pulverised fuel ash (PFA), ground granulated blast furnace slag (GGBS), microsilica (MS) and metakaolin (MK) in marine environment and highway structures. The resistance offered by these concretes has been related to the low mobility of chloride ions due to either the reduction in the number of interconnected pores as a result of the pozzolanic reaction of the ACMs or the chemical binding with the cement hydrates. However, the secondary reaction products are formed slowly in Portland cement concrete containing ACMs and as a result it is likely that the resistance offered to the penetration of chloride ions also increases slowly with time. In order to monitor the continuous behaviour of concretes containing these ACMs in a chloride exposure regime, an investigation was carried out, the results of which are reported in this paper. Ten different concrete mixes were subjected to a cyclic ponding regime with 0.55 M sodium chloride solution and the changes in concrete were monitored by measuring the changes in resistance between pairs of stainless steel electrodes embedded in the concrete at different depths from the exposed surface. The test was continued for nearly one year. The results indicated that, although the resistance of concrete decreased initially due to the penetration of chlorides, in the longer term the resistance of concretes containing ACMs outperformed the control concrete made with ordinary Portland cement (OPC). Drilled dust samples extracted after different durations of ponding were tested for the chloride content, which confirmed that the increase in resistance of the ACMs was due to the combined effects of the reduction in the penetration of chlorides and the continuous hydration activity of the ACMs. (P.A.M. Basheer).

Two hundred and thirty individual clones of microorganisms were recovered from milk tanks and milking machine surfaces at two distinct farms (Bejaja City, Algeria). Of these clones, 130 were identified as lactic acid bacteria (LAB). In addition Escherichia coli, Salmonella, Staphylococcus aureus and Pseudomonas aeruginosa species were identified in the remaining 100 isolates-spoilage isolate. These isolates were assayed for ability to form biofilms. S. aureus, Lactobacillus brevis strains LB1F2, LB14F1 and LB15F1, and Lactobacillus pentosus strains LB2F2 and LB3F2 were identified as the best biofilm formers. Besides, these LAB isolates were able to produce proteinaceous substances with antagonism against the aforementioned spoilage isolates, when grown in MRS or TSB-YE media. During the screening, L. pentosus LB3F2 exhibited the highest antibacterial activity when grown in TSB-YE medium at 30°C. Additionally, L. pentosus LB3F2 was able to strongly hamper the adhesion of S. aureus SA3 on abiotic surfaces as polystyrene and stainless steel slides. LAB isolates did not show any hemolytic activity and all of them were sensitive to different families of antibiotic tested. It should be pointed out that LB3F2 isolate was not cytotoxic on the intestinal cells but could stimulate their metabolic activity. This report unveiled the potential of LB1F2, LB14F1, LB15F1, LB2F2, and LB3F2 isolates to be used as natural barrier or competitive exclusion organism in the food processing sector as well as a positive biofilm forming bacteria.

The effects of cryogenic cooling on cutting forces in the milling process of AISI 304 stainless steel were investigated experimentally. Cryogenic cooling was achieved by spraying liquid nitrogen to tool, chips and material interfaces using a pipe with an internal diameter of 1 mm; the flow rate of liquid nitrogen was 5.2 L/min; two cutting directions (climbing and conventional milling), two machining conditions (dry and cryogenic cooling) and four cutting speeds (80, 120, 160 and 200 m/min) were used in the milling process. Cryogenic cooling and cutting speed are found to be effective on cutting forces. Cutting forces and torque in cryogenic milling are higher than those in dry milling. Cutting force is increased as the cutting speed is increased. Tool fritter around insert nose radius is the main problem of climb milling method in cryogenic cooling at low cutting speeds.

This work reports on RGA studies relative to pump-down and ultimate pressure experiments made on a 40 l UHV chamber with a specially designed non-evaporable getter (NEG) pump operated in series with the main pumping group, comprising a 600 l/s hybrid turbo pump backed by a 12 m/h rotary pump. Experiments were also made with a 50 l/s turbomolecular drag pump inserted between the exhaust of the hybrid turbo pump and the intake pipe of the rotary pump. The NEG pump, located on top of the main turbo pump, was realized using "ve NEG elements arranged around the walls of a cylindrical cartridge inserted inside a stainless-steel nipple having an inner diameter of 150 mm. A single NEG element, consisting in a E 5 mm, 720 mm long rod, shaped as a sinusoid, was prepared by sintering ca. 20 g of pure titanium on a E 0.5 mm nichrome wire. The NEG pump allowed for a tenfold reduction of H O partial pressure and a reduction of the ultimate pressure from 1;10\ to 1;10\ mbar. In particular, because of the sorption characteristics for hydrogen of NEG pumps, the H partial pressure could be signi"cantly reduced by e!ectively dealing with the hydrogen backstreaming, typical of turbo pumps.

This in vitro study evaluated the shear bond strength (SBS) between ceramic brackets (CBs) and resin composite restorations (RCRs) prepared using different surface treatments. The findings were also compared with a similar study that used stainless steel brackets (SSBs). Forty-five premolars were restored with a nano-hybrid composite resin (Tetric EvoCeram) and randomly assigned to three surface treatment groups: group 1, 5 per cent hydrofluoric acid (HF); group 2, air abrasion (50 mm alumina particles); and group 3, diamond bur. Specimens were bonded with CBs (Fascination) and exposed to thermo-cycling (500 cycles). The shear force at a crosshead speed of 1 mm/minute was transmitted to brackets. The adhesive remnant index (ARIs) scores were recorded after bracket failure. The analysis of SBS variance (P < 0.01) and chi-square test of ARIs scores (P < 0.01) revealed significant differences among three groups tested. The SBS in group 3 (mean: 26.34 ± 4.76 MPa) and group 2 (mean: 26.68 ± 5.93 MPa) was significantly higher than group 1 (mean: 16.25 ± 5.42 MPa). The SBS was significantly higher in CBs (mean: 23.09 ± 7.19 MPa) compared to SSBs (mean: 15.56 ± 5.13 MPa). High ARIs (100 per cent) occurred in SSBs treated with a diamond bur, whereas CBs primarily failed at the resin-adhesive interface (P < 0.01). In two-thirds of the specimens (SSBs or CBs), no adhesive was left on the restoration after HF conditioning. The ARIs profile of CBs and SSBs that received surface treatments with air abrasion were similar (P > 0.05) and bond failure occurred mainly in adhesive-bracket base and resin-adhesive interfaces. The diamond bur surface treatment is recommended as a safe and cost-effective method of bonding CBs to RCRs.

Electrodes constructed with different electroactive materials such as platinum (Pt), nickel (Ni), 304 stainless steel (SS) and low carbon steel (LCS) have been tested in water electrolysis using 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF 4). All experiments were performed at room temperature using a classical Hoffman's cell operating at atmospheric pressure and at different cathodic potentials. For the electrodes studied herein, in the presence of a 10 vol.% solution of BMI.BF 4 in water, current densities (j) in the range 10-42 mA cm −2 were observed, with overall hydrogen production efficiencies (experimental/theoretical hydrogen production ratio) between 82 and 98%. The highest j values obtained with Pt, Ni, SS and LCS electrodes were 30, 12, 10 and 42 mA cm −2 , respectively, and all efficiencies were in the 85-99% range. These comparative results show that the LCS electrocatalyst constitutes an attractive alternative for the technological production of high purity hydrogen by water electrolysis reaction since the LCS electrode gave j and efficiencies as high as those observed with platinum electrodes.

Nowadays, micro metal injection molding has become among the promising method in powder metallurgy research to produce small-scale intricate part at an effective process and competitive cost for mass production. The success of injection molding is greatly influenced by feedstock characteristic. This paper investigated the optimization of highest green strength which plays an important characteristic in determining the successful of micro MIM. In this paper, stainless steel SS 316L with D 50 = 5.96µm was used with composite binder, which consists of PEG (Polyethelena Glycol), PMMA (Polymethyl Methacrilate) and SA (Stearic Acid). Feedstock with 61.5% with several injection parameters were optimized which highly significant through screening experiment such as injection pressure(A), injection temperature(B), mold temperature(C), injection time(D) and holding time(E). Besides that, interaction effects between injection pressure, injection temperature and mold temperature were also considered to optimize in the Taguchi's orthogonal array. Analysis of variance (ANOVA) in terms of signal-to-noise ratio (S/N-larger is better) for green strength was also presented in this paper. Result shows that interaction between injection temperature and mold temperature (BxC) give highest significant factor followed by interaction between injection pressure and injection temperature (AxB). Single factor that also contributes to significant optimization are mold temperature(C), injection time(D) and injection pressure(A). This study shows that Taguchi method would be among the best method to solve the problem with minimum number of trials.

Purpose: The purpose of this retrospective study was to explore clinical outcomes for NuSmile anterior preveneered stainless steel crowns. Methods: A convenience sample of healthy children treated with anterior crowns was selected from a teaching clinic and private offi ce. Crowns were placed by either a private practice dentist or pediatric dental resident. Clearly defi ned clinical outcomes were assessed by 3 calibrated examiners at recall, including: (1) presence; (2) chipping; (3) wear; (4) crazing; and (5) marginal location by clinical and radiographic examination. examiners at recall, including: (1) presence; (2) chipping; (3) wear; (4) crazing; and (5) marginal location by clinical and radiographic examination. examiners at recall, including: (1) presence; (2) chipping; (3) wear; (4) crazing; and (5) marginal location by clinical and radiographic examination. Factors affecting placement-such as operator experience and behavior-were also assessed. Results: Results: In 46 subjects (21 females, 25 males; mean In 46 subjects (21 females, 25 males; mean age at placement=4 years, 2 months), 226 crowns with a mean post-placement time of 12.9 months were evaluated. Only 2 crowns matched natural teeth, with NuSmile crowns lighter in 83% of subjects. Most crowns were normal in size. Eighty-eight percent resisted fracture for 6 months. All but 3 crowns resisted color change for 6 months. Canine crowns were the least successful, but overall 91% of crowns retained good to excellent clinical appearance. Conclusions: NuSmile anterior preveneered crowns are a clinically successful restoration for primary incisors with early childhood caries. (Pediatr Dent 2007;29:377-81) .

The brake system is an important part of an automobile. It plays a vital role in helping the driver to reduce the speed of an automobile or to stop the automobile. Initially, when automobiles were first introduced, they were equipped with drum brakes. These drum brakes were cheap, easy to install and atmospheric agents cannot hinder their performance. Despite these advantages, the major disadvantage of the drum brake system is the poor heat dissipation. To tackle this problem, the automotive engineers came up with the disc brake system. The brake rotor is one of the most critical components of the disc brake system. The brake rotor is made up of a pure metal or a metal with certain reinforcements. These brake rotors are circular with perforations made in a particular manner to enable faster dissipation. These perforations help to reduce the weight of the disc brake rotor. The disc brake rotor is fixed to the wheel hub with brake calipers. In this review article, I will be critically analyzing various research articles on the thermal and mechanical properties of various brake rotor materials used in automobiles.

This work presents a method to perform a surface finish control using a computer vision system. Test parts used were made of AISI 303 stainless steel and were machined with a MUPEM CNC multi-turret parallel lathe. Using a Pulnix PE2015 B/W camera, a difiuse illumination and a industrial zoom, 140 images were acquired. We have applied a vertical Prewitt filter to all the images obtaining two sets, the original one and the filtered. We have described the images using three difierent methods. The first features vector was composed by the mean, standard deviation, skewness and kurtosis of the image histogram. The second features vectol was made up by four Haralick descriptorscontrast, correlation, ener8y and homogeneity. The last one was composed by 9 Laws descriptors. Using &-nn we have obtained a hit rate around 90 % with filtered images and, the best one, using Laws features vector of 92.14To with unfiltered images. These results show that it is feasible to use texture descriptom to evaluate the rugosity of metallic pads in the context of product quality inspection.

Most microbial electrolysis cells (MECs) contain only a single set of electrodes. In order to examine the scalability of a multiple-electrode design, we constructed a 2.5 L MEC containing 8 separate electrode pairs made of graphite fiber brush anodes pre-acclimated for current generation using acetate, and 304 stainless steel mesh cathodes (64 m2/m3). Under continuous flow conditions and a one day hydraulic