Polished Finish Research Articles

Atomic Force Microscopy Characterization of Electrochemically Polished Nickel-Titanium Memory Alloy

Atomic force microscopy (AFM) is a powerful characterization technique used for monitoring metals or metal alloys surfaces changes [1-14]. AFM works by using a small probe, typically with a sharp tip, to scan the surface of a sample. As the probe moves over the surface, it measures the height and other properties of the surface topography, allowing for detailed analysis of the surface characteristics. Using AFM, it is possible to obtain high-resolution images in 2-dimintinal (2-D) or 3-dimintinal (3-D), allowing for detailed analysis of the surface morphology, roughness, and other properties. AFM can also be used to measure surface features, such as the height and depth of surface defects, or the thickness of surface coatings.Smooth surfaces of metals or metal alloys are needed for many biomedical applications such as implants and stents. Electrochemical polishing (EP) is a process used to smooth and improve the surface finish of metals or alloys by selectively removing surface roughness using an optimum electric current. The resulting surface can have a highly polished and uniform finish. In this study, AFM is used to monitor the surface changed before and after EP of memory alloy (Nickel-Titanium, Ni-Ti Alloy). AFM image of a Ni-Ti Alloy’s surface is polished using a current density ranging from 0 to 0.147 A/cm2, which shows a highly polished surface after for 15 minutes. Surface roughness of the Ni-Ti alloy in ionic liquid as an acid free EP resulted in surface roughness significantly is reduced from 64 nm (before EP) to 11 nm without significantly altering the alloy elemental composition. This study provides an electrochemical acid free EP method to effectively control the relative smoothness of Ni-Ti implants at the nanoscale (less than 12 nm) which could offer many potential biomedical applications including controlling cell interactions with Ni-Ti alloy at bio-interfaces. Overall, AFM is a powerful tool for characterizing metal surfaces after electrochemical polishing, providing detailed information about the surface morphology and chemical composition that can be useful for a range of applications, from materials science research to quality control in manufacturing. References Mahapatro, T. D. Matos Negrón, C. Bonner, and T. M. Abdel-Fattah, J. Biomater. Tissue Eng., 3, 196-204 (2013).Bhure, A. Mahapatro, C. Bonner, T. M. Abdel-Fattah, Materials Science and Engineering: C, 33(4), 2050-2058 (2013).Bhure, T. M. Abdel-Fattah, C. Bonner, J. C. Hall, and A. Mahapatro, Applied Surface Science, 257(13), 5605-5612 (2011).M. Abdel-Fattah, D. Loftis and A.Mahapatro, Journal of Biomedical Nanotechnology, 7(6) 794-800 (2011).M. Abdel-Fattah, D. Loftis and A. Mahapatro, Journal of Surfaces and Interfaces of Materials, 3, 67-74 (2015)JD Loftis, TM Abdel-Fattah, Colloids and Surfaces A: Physicochemical and Engineering Aspects 511, 113-119 (2016)M. Abdel-Fattah, D. Loftis and A. Mahapatro, Nanoscience and Nanotechnology, 5(2), 36-44 (2015)Bhure, T. M. Abdel-Fattah, C. Bonner1, J. C. Hall, and A. Mahapatro, Journal of Biomedical Nanotechnology, 6(2), 117-128 (2010).M. Abdel-Fattah, D. Loftis, ECS Transactions, 25, (39), 57-61 (2010).M. Abdel-Fattah, D. Loftis, A. Mahapatro, ECS Transactions, 25(19), 57-61 (2010).M. Abdel-Fattah, Derek Loftis, ECS Transactions, 25(7), 327-332 (2009).AI Wixtrom, JE Buhler, CE Reece, TM Abdel-Fattah, Journal of The Electrochemical Society 160 (3), E22 (2013)AI Wixtrom, JE Buhler, CE Reece, TM Abdel-Fattah, Journal of Environmental Chemical Engineering 1 (1-2), 18-22 (2013)M. Abdel-Fattah and J, D. Loftis, Sustainable Chemistry, 3(2), 238-247 (2022)M. Abdel-Fattah and J. D. Loftis, Molecules, 25, 23, 5712 (2020)

Stone Endurance: A Comparative Analysis of Natural and Artificial Weathering on Stone Longevity

The long-term endurance of building stones must be assured since their longevity has repercussions for their economic and social value. Frequently, slabs for flooring and cladding are installed with polished finishing in outdoor environments for technical and ornamental purposes in cultural heritage sites and modern civil architecture. Compared to any other finishing, glossy surfaces are rather vulnerable to wear, particularly when they interact with slightly acidic rainwater. Several hydrophobic treatments are applied to prevent this damage by preventing contact between rain and stone; such treatments are efficient but sometimes non-durable. Stakeholders and conservation scientists need better methods to anticipate the future behaviour of this building material and hydrophobic solutions. Complying with this demand, a comparison is made between outdoor natural ageing and artificial weathering, reproduced by UVA radiation, moisture and spray accelerated weathering. Artificial weathering is applied to predict the behaviour of stones over time in the real environment. Data obtained through the measurement of gloss and colour parameters, the detection of micro-textures through SEM, and the calculation of micro-roughness using a digital rugosimeter demonstrate that weakly acidic rainwater is the main cause of superficial decay of stone finishing over just six months of outdoor exposure. This period corresponds to 7–14 days of artificial weathering. Furthermore, the loss of efficiency and durability of the hydrophobic coatings is detected by measuring the static contact angle. This highlights that even if a protective treatment was proficient, it could easily deteriorate in normal weathering conditions if applied on polished, low-porosity stone. Additionally, water vapour permeability indicates variations of regular vapour transmission through the stones due to ageing. The first solution to threats is the prevention of pathologies, including aesthetic ones. A careful choice of the most suitable lithotype finish and an environmental study represent an existing solution to the problem. It must be highlighted that aesthetic requirements should not be prioritised to detriment of the technical requirements of architectural quality, performance, durability, and safety.

Surface roughness and translucency of glazed versus polished cubic ultra-translucent multi-layered zirconia: An in-vitro study

Statement of the problem: The final surface finish after sintering or after adjustment procedure of monolithic zirconia restorations is an important issue. Currently, there is lack of evidence based recommendations regarding the best surface finishing protocols for achieving optimal surface roughness and translucency of cubic multi layered ultra-translucent monolithic zirconia. Aim: The purpose of this in vitro study was to assess the effect of surface finish protocols (glazing versus polishing) on the surface roughness and translucency of cubic ultra-translucent multi-layered zirconia. Materials and Methods: CAD/CAM fabricated ultra-translucent multi-layer cubic zirconia cylinders were cut into disc-shaped samples and sintered to end up with (16) discs of uniform dimensions 11mm diameter and 0.6mm thickness. Disc samples were divided into two equal groups according to the surface finish protocols. Group G: glazing surface finish. Group P: polishing surface finish. Surface roughness (Ra) was assessed by a non-contact profilometer and translucent parameter (TP) was assessed by spectrophotometer. Results: Surface roughness of studied samples of group 1 recorded (0.253±0.0009 µm) and (0.251±0.0024 µm) before and after glazing respectively. While for group 2 revealed (0.2547±0.0002 µm) and (0.2545±0.001 µm) respectively. While for translucent parameter of group 1 revealed (16.0553±2.659) and (15.3714±9.773) before and after glazing respectively. While for group 2 revealed (16.0553±2.659) and (14.242±8.325) respectively. There was a significant difference between both groups showing that glazing gave a smoother surface and more translucency than a polishing surface finish protocol. Conclusions: Glazing of cubic ultra-translucent multi-layered zirconia is better than polished surface finishing protocol regarding surface roughness and translucency.

Effects of staining agents on an ornamental granite

Natural stone is quite popular and is commonly used in building interiors, for its aesthetic appeal and for its performance, durability and environmentally-friendly composition. Natural stone also adds considerably to the real estate market value of houses. Different types of natural stone, including granite, can be used in interior design. The stones are thus exposed to staining and are affected differently depending on the staining agent involved. The European standard UNE-EN 16301:2014 defines a procedure for determining the sensitivity of ornamental stones to accidental staining. However, a more detailed study of the physical and chemical effects of such staining agents on stones is required. Adapting this standard, nine different stains (red wine, olive oil, instant coffee, ketchup, cola, citric acid, artificial urine, lime juice and blueberry juice) were applied to a granite commonly used in the Iberian Peninsula. The granite had a polished finish, and three cycles of staining-cleaning (with an anionic detergent) were applied. In the standard evaluation, a qualitative score is awarded on a text-based scale, by external evaluators. In this study, a more complex physical, chemical and texture evaluation of the granite surfaces was carried out to determine the sensitivity of the granite to accidental staining. Colour, roughness, hydrophobicity, gloss and texture were considered key parameters for evaluating the sensitivity of the granite to accidental staining.The sensitivity of the granite to staining clearly depended on the characteristics of the staining agents. In terms of aesthetic properties, all stains except lime juice caused significant colour changes on the granite surface. None of the stains, except red wine, caused important changes in surface gloss. The staining agents, particularly ketchup, blueberry juice and citric acid increased the wettability of the granite surface, thus further enhancing the absorption of aqueous solutions. Olive oil residues were not completely removed from stone surfaces after the cleaning process and therefore caused an increase in the static contact angle, although the stained granite surfaces remained hydrophilic. Citric acid solution caused a chemical interaction with quartz grains, highlighted by the formation of etch pits.

Confecção e Análise de um Piranômetro Fotovoltaico de Baixo Custo

The present research aimed the development and the evaluation of a low cost photovoltaic pyranometer, built from easily found materials in the national market. Therefore, models of small polycrystalline silicon photovoltaic modules were evaluated. A pyranometer body prototype with was developed with machined engineering plastic. Also, the behavior of diffusers built with three different materials Thecnyl®, acrylic and polyvinyl chloride were analyzed. For the chosen one, two distinct thicknesses were tested, as well as polished and matte surface finishing. All the tests were performed in the field, in the Federal University Rural of Semiarid weather station, from Mossoro-RN, between 2017 august and 2018 march. The prototypes results were compared to a secondary class reference pyranometer. The experiments data were collected by an automatic datalogger and its handling was accomplished considering the regulation ISO 9847:1992 recommendations. The prototype final model has shown a satisfactory performance considering measurements in the hourly and daily scales. In the total hourly values measurements, considering the interval of 6 a.m. to 6 p.m., the absolute percentage relative error was 2,26%, the minimum was 0,433% and the maximum was 8,10%. In the total daily values, the absolute percentage relative error was 0,50%, the minimum was 0,16% and the maximum was 0,93%.

Influence of Surface Finish on Small Punch Testing of 9Cr Eurofer-97 Steel

Abstract This study investigated the effect of surface finish on the deformation behavior of Eurofer-97 steel during room-temperature small punch testing. The surface finish of specimens was varied from coarse to fine (ranging from P240-grit silicon carbide paper to a polished finish using 0.06-μm colloidal silica). Testing was conducted on 8-mm diameter by 0.5-mm-thick disks using a 1-mm-radius punch head. No significant change was observed in the elastic-plastic transition load, maximum load, displacement at maximum load, or displacement at failure. Similarly, in all cases, failure occurred in a ductile manner, yielding a dimpled fracture surface. Although friction and surface defects may influence the output of small punch tests, the effect of altering the specimen surface finish alone was negligible in this case, indicating this is not a dominant factor in small punch testing.

Effects of Surface Modification by Means of Low-Temperature Plasma Nitriding on Wetting and Corrosion Behavior of Austenitic Stainless Steel

Low-temperature nitriding of austenitic stainless steels produces modified surface layers, consisting mainly of the S phase, which improve surface hardness and corrosion resistance. Because of the localized plastic deformations, owing to modified layer formation, and ion bombardment occurring during the process itself, this treatment produces also modifications of surface morphology and roughness, which can affect wettability and corrosion behavior. In this study the effects of plasma nitriding, performed using different treatment conditions, on the surface morphology and roughness, and thus on wettability and corrosion resistance, of AISI 202 specimens with different initial finishings (2D and polished finishing) were investigated. Different probe liquids, having both high (bi-distilled water and solution of 3.5% NaCl) and low (ethanol and rapeseed oil) surface tension, were employed for assessing the wetting behavior with the sessile drop method. The contact angle values for water increased markedly when nitriding was performed on polished samples, while this increase was smaller for 2D samples, and on selected specimens a hydrophobic behavior was observed. Very low contact angle values were registered using low surface tension liquids, suggesting an oleophilic behavior. Corrosion resistance in a 5% NaCl solution was assessed, and it depended on the characteristics of the nitrided specimens.

A polished finish

In-tank storage heaters used within plastic process tanks are a major cause of fire in the electroplating and anodising industry. David Hemsley explains the precautions that should be taken to reduce the risk of fire in this major industrial sector.

Status of nickel free stainless steel in biomedical field: A review of last 10 years and what else can be done

The area of biomaterials is a continuous research area. Among others, stainless steels are also used in medical applications such as fracture plates, wires, sutures and implants etc. Surgical grade 316 L stainless steel is specifically used for medical application. It primarily contains nickel, chromium and molybdenum wherein the purpose of nickel is to retain the FCC structure of stainless steel almost at any temperature unlike conventional steel which has ferrite (BCC structure) in ambient temperature. Also, nickel imparts a polished and glossy finish to surgical grade stainless steel which is an important factor to keep it hygienic. But, the harmful effect of nickel on human body has been investigated and reported for quite some time now. The adverse effect of nickel (Ni) ions that release from stainless steel upon crevice and pitting corrosion has led to the evolution of Ni-free stainless steel with high nitrogen content. This paper briefly reviews the effect of nickel release in human body and let go the presence of nickel in stainless steel by uplifting nitrogen content in it. Furthermore, the groundbreaking findings on Ni-free stainless steel in last 10 years are presented and the possibilities of further developments have been hypothesized.

Fatigue and Static Properties of Built-up Friction Stir Welded Ti-6Al-4V I-Beams

Abstract Modern aircraft systems use high-strength alloys, such as Ti-6Al-4V (Ti-6-4), for their components. The advantage of using Ti-6-4 is its high corrosion resistance and low weight to strength ratio when compared with other metals. The downside of using titanium is its high cost and lead time associated with procurement in addition to the material wastage that occurs with machining different cross-sectional geometries. Built-up titanium beams fabricated using friction stir welding (FSW) and readily available titanium plates may be a viable alternative that reduces these expenses. This study investigates the fatigue and static strengths of built-up titanium I-beams using FSW and 7-mm-thick Ti-6-4 plate material and compares the results with strengths of representative coupon specimens. Coupons in the transverse and longitudinal directions of the FSW were evaluated for both polished and as-welded FSW surfaces. The results of the investigation showed that the static flexural strength of the built-up I-beam reached 57 % of the yield strength of the Ti-6-4 plate material. The fatigue strengths of the two I-beams tested reached 87 and 63 % of comparable coupon-level specimens with as-welded and polished finishes, respectively. Failures in these beams initiated at discontinuities in the welded fillet region, which suggests that strength and fatigue performance of built-up titanium I-beams can be improved through more consistent FSW methods for Ti-6-4 plate materials.

Laser Surface Blasting of Granite Stones Using a Laser Scanning System

Granite stones are the most abundant rock of the crust. Due to their beauty, durability, and virtually zero maintenance, they have been used widely since ancient times in all types of construction, as a structural or decorative element. Commonly, this material is used with a polished finishing, but there has been an increased interest in giving it a rustic aspect, mainly for decorative or functional reasons, e.g., to reduce slipping. Rough surfaces are usually produced by means of bush hammering, but this is an extremely noisy and inefficient process. In this work we have explored the capabilities and limits of a laser blasting process assisted by a scanning system in order to produce precise and controllable roughness on two varieties of granite plates. It was found that laser blasting of thin granite tiles can be accomplished with processing widths up to 250 mm at medium-low laser power, obtaining a rustic aspect suitable for use in façades, paving, or flooring. Moreover, laser scanner systems are capable of enhancing the productivity of this process up to ten times greater than that found in previous works.

Global Heritage Stone: Belgian black ‘marbles’

Abstract The appellation ‘Belgian black “marbles”’ usually designates dark fine-grained limestones present in the Paleozoic substrate of south Belgium. They have been extracted mostly in Frasnian (Upper Devonian) and Viséan (Lower Carboniferous) strata, in various different localities (Namur, Dinant, Theux, Basècles, Mazy-Golzinne among others). Nearly devoid of fossils and veins, they take a mirror-like polished finish, with a pure black colour. These limestones were already known during Antiquity but were only intensively exploited from the Middle Ages. Many different uses were made of these stones, for architecture, decoration or sculpture, in religious or civil contexts, following all the successive styles, Romanesque, Gothic, Renaissance, baroque and so on. All these products, architectural, decorative and sculptural, were probably manufactured close to the quarries and were first exported to neighbouring countries (France and the Netherlands), then to all of Europe (Italy, Germany, Denmark, Poland, Baltic states, etc.) and, by the beginning of the nineteenth century, worldwide. They were always considered as high value-added objects, which allowed them to travel great distances from their origin. Thousands of references document the widespread use of these exceptional natural stones. They were employed, among other famous applications, as the black background of the Pietre dure marquetry of Florence. Some other lesser uses were either for musical instruments or lithographic stones. Today only one underground quarry exploits the black ‘marble’, at Golzinne (close to Namur). This prestigious material, with its dark aura, is suitable for recognition as a Global Heritage Stone Resource.

COMPARATIVE STUDY OF THE OPTICAL PROPERTIES EFFECT OF THE FACADE EXTERIOR COATING ON THE BUILDING ENERGY DEMAND

There are different technologies to optimize the use of solar energy in construction systems, with the aim of improving the building energy efficiency and also to reduce the effect of solar radiation on the exterior coatings, which in turn affects the urban areas warming. Among these technologies, chromogenic devices based on materials whose optical properties can be reversibly modified by some external stimulus have become relevant. These materials are especially interesting because they adapt to variations of solar radiation during the day and throughout the different seasons of the year. The facade coating may have different types of texture or color, which determine specific optical properties. One of these properties is the absorptance, which determines the amount of solar radiation absorbed by the material with respect to the incident radiation. The effect of the absorptance on the building energy demand will be conditioned by other parameters that also influence it, such as the climatic zone, orientation and thermal properties of the wall. In the work presented, the influence of the optical properties of three types of exterior facade coating on the building energy demand is analyzed. The materials chosen for this study are a conventional white Portland cement, a belitic cement synthesized in the laboratory by a process of low energy and low CO2 emissions and a brick representative of a brickwork wall, presenting the first two a more polished finish and clearer colors than the second. The final objective of this study is to determine the parameters that optimize the utilization of the optical properties of the studied coatings in the building energy efficiency.

Polished Cemented Femoral Stems Have a Lower Rate of Revision Than Matt Finished Cemented Stems in Total Hip Arthroplasty: An Analysis of 96,315 Cemented Femoral Stems

BackgroundMatt and polished femoral stems have been historically grouped together in registry assessment of the outcome of cemented femoral stems in total hip arthroplasty. This is despite differences in the mode of fixation and biomechanics of loading. The aims of this study are to compare the survivorship of polished tapered stems with matt finished cemented stems. MethodsData on primary total hip arthroplasty undertaken for a diagnosis of osteoarthritis from September 1999 to December 2014 were included from a National Joint Registry. Revision rates of the 2 different types of femoral components were compared. ResultsThere were 96,315 cemented femoral stems included, of which 82,972 were polished tapered and 13,343 matt finish. The cumulative percent revision at 14 years of polished stems was 3.6% (3.0-4.2) compared to 4.9% (4.1-5.7) for matt finish stems. Polished tapered stems had a significantly lower revision rate of femoral revision (hazard ratio 0.56, P < .001). This difference is evident in patients aged <75, and becomes apparent in the mid-term and continues to increase with time. Aseptic loosening accounts for 75% of revisions of matt finish stems compared to 20% for polished tapered stems. ConclusionAlthough both polished and matt finish stems have excellent early to mid-term results, the long-term survivorship of polished stems is significantly better, with aseptic loosening becoming an issue with matt finish stems. In the future reports of cement fixation for femoral stems may benefit from separate analysis of polished and matt finish.

The Historical Importance and Architectonic Relevance of the “Extinct” Arrábida Breccia

The Arrabida Breccia is a type of chromatic rock with a very unusual texture, appearing only in the current geographical area of the Natural Park of Arrabida, and thus, its extraction is definitively finished. Due to its petrographic nature, it is very sensitive to weathering, particularly to rainwater. It has had numerous uses for at least 2000 years since the occupation of Iberia by the Romans, and which evolved over time from exterior to interior structures. Since the beginning of the Baroque, it is almost exclusively linked to the interior decorative arts, in polished finishing. Its use had a greater expression linked to the Gothic-Manueline style, closely associated with the epic Portuguese, roughly in the transition in fifteenth to sixteenth centuries particularly during the reign of King Manuel I who would have particular preference for this rock. Its use is characterised by being quite confined, especially as the resource has always been relatively scarce regarding known deposits. Although most of the known applications are located in Portugal, especially in the regions of Setubal and Lisbon, there are also examples of its application in other countries, namely in the Mediterranean Europe and Brazil, largely in buildings classified as of National Interest and in building classified as World Heritage or Architectural Heritage (UNESCO). Due to the above facts, the need to preserve some extracted but not used blocks is also discussed in this work both for the purposes of preservation and restoration of monuments as well as the valuation of the old mines for educational and recreational purposes.

The Exeter Trauma Stem: A radiographic follow-up at minimum of five years post implantation

IntroductionThe Exeter Trauma Stem (ETS) has been recommended by National Institute of Clinical Excellence (NICE) guidelines in the United Kingdom as a proven, cemented stem. A single laboratory study in the literature has raised possible concerns about the polished finish of the ETS and subsequent potential for accelerated loosening although there is little clinical evidence to support or refute this. MethodsThe aim of this study was to assess clinical outcomes of the ETS at a minimum of five years post implantation. Primary outcomes were radiological loosening at a minimum of five years along with survivorship of the implant. Patient demographics were prospectively collected and followed up. Results218 ETS’s (in 214 patients) were implanted from June 2002 until August 2008 in a single centre by a wide variety of surgeons of differing grades. Of these, 16 underwent revision surgery for fracture (2), dislocation (3), infection (1) and acetabular erosion (10) but there were no revisions for aseptic loosening of the implant. There were 64.0% (137/214) patients that had died by the time of this study. Of the remaining patients, 90 had radiographs of their hips at a minimum of 5 years with 36 of these at a minimum of 7 years post implantation. None of these had evidence of loosening. ConclusionThe ETS is a robust and suitable stem for implantation in patients with hip fractures. There are no clinical suspicions or increased rates of loosening with the ETS in our study. The concerns about surface finish are not borne out in our clinical study which shows no evidence of loosening at a minimum of five years post operation. It confers many advantages including ease of revision and it should continue to be used as per NICE guidelines.

Surface topography evolution of Ni-based single crystal superalloy under laser shock: Formation of the nano-scale surface reliefs

The aim of the study was to investigate the effect of laser shock peening (LSP) on surface topography evolution of metallic targets. Samples manufactured by a Ni-based single crystal superalloy with polished finish were treated by LSP, and the surface topographies before and after LSP were examined by non-contact White-Light Interferometer (WLI). Results showed the following three aspects: (a) By taking advantage of WLI, the shrinkage porosities and the interdendritic structures were observed simultaneously. (b) With the increasing impact times, the round pit induced by laser shock became deeper. (c) The nano-scale surface reliefs were found on the bottom of round pit induced by LSP, and the specific plastic flow of metallic materials under the action of compressive stresses was deemed as the primary contributor to the formation of surface reliefs. It revealed a novel microscale plastic deformation phenomenon of metallic materials in surface strengthening.

A fast method for optical simulation of flood maps of light-sharing detector modules

Optical simulation of the detector module level is highly desired for Position Emission Tomography (PET) system design. Commonly used simulation toolkits such as GATE are not efficient in the optical simulation of detector modules with complicated light-sharing configurations, where a vast amount of photons need to be tracked. We present a fast approach based on a simplified specular reflectance model and a structured light-tracking algorithm to speed up the photon tracking in detector modules constructed with polished finish and specular reflector materials. We simulated conventional block detector designs with different slotted light guide patterns using the new approach and compared the outcomes with those from GATE simulations. While the two approaches generated comparable flood maps, the new approach was more than 200–600 times faster. The new approach has also been validated by constructing a prototype detector and comparing the simulated flood map with the experimental flood map. The experimental flood map has nearly uniformly distributed spots similar to those in the simulated flood map. In conclusion, the new approach provides a fast and reliable simulation tool for assisting in the development of light-sharing-based detector modules with a polished surface finish and using specular reflector materials.

The effect of a collar and surface finish on cemented femoral stems: a prospective randomised trial of four stem designs

The optimal design for a cemented femoral stem remains a matter of debate. Over time, the shape, surface finish and collar have all been modified in various ways. A clear consensus has not yet emerged regarding the relative merits of even the most basic design features of the stem. We undertook a prospective randomised trial comparing surface finish and the effect of a collar on cemented femoral component subsidence, survivorship and clinical function. One hundred and sixty three primary total hip replacement patients were recruited prospectively and randomised to one of four groups to receive a cemented femoral stem with either a matt or polished finish, and with or without a collar. At two years, although there was a trend for increased subsidence in the matt collarless group, this was not statistically significant (p = 0.18). At a mean of 10.1 years follow-up, WOMAC scores for the surviving implants were good, (Range of means 89-93) without significant differences. Using revision or radiographic loosening as the endpoint, survivorship of the entire cohort was 93 % at 11 yrs, (CI 87-97 %). There were no significant differences in survivorship between the two groups with polished stems or the two groups with matt stems. A comparison of the two collarless stems demonstrated a statistically significant difference in survivorship between polished (100 %) and matt (88 %) finishes (p = 0.02). In the presence of a collar, surface finish did not significantly affect survivorship or function. Between the two collarless groups a polished surface conferred an improved survivorship.

Rock Finishing and Response to Salt Fog Atmosphere

Seven silicate rocks used as ornamental stones and having different surface finishing were submitted to salt fog atmospheres in order to compare different susceptibilities to alteration. Polished, honed, hammered and flamed finishing types were tested. Rocks come from Portugal, Brazil and Angola and are widely commercialized. Samples covered quartz rich rocks, silica saturated and undersaturated rocks, mono and plurimineralic rocks, coarse and fine grained rocks. Mineral composition, texture and open porosity showed to be important parameters which determine mass loss among samples, but the finishing type was very effective within samples. Mass loss and porosity increase are higher on hammered samples, contrasted with the lowest loss values on polished samples. The effect of surface hydrophobicity and roughness on the samples having polished finishing was also analysed by atomic force microscopy (AFM) and water contact angle (WCA), indicating that texture and mineral diversity influence the hydrophobic character of the rock surfaces.