Changes In Surface Appearance Research Articles

Effect of anisotropic abrasive damage on mass loss and ultimate tensile properties of the stretch denim fabric

PurposeIn recent times, stretch denim garments have become very popular amongst consumers as the garment is able to provide body fit and body comfort at the same time. The purpose of this study is to investigate the effect of abrasion on the change in surface appearance, mass loss and ultimate tensile properties of the stretch denim fabric in different directions (warp, weft and biased).Design/methodology/approachAfter abrading the fabrics in three different directions (warp, weft and biased), the loss in ultimate tensile properties, mass loss and surface appearance has been investigated in the respective directions of abrasion (warp, weft and biased). The study also encompasses the effect of different types of stretch yarn with varying levels of elastane content on such unidirectional abrasive damage.FindingsIt is seen that with the same level of abrasion cycles, the fabric's response in terms of mass loss and loss in ultimate tensile properties are different in different directions. The mass loss due to abrasion in biased direction is found to be minimum. The loss in ultimate tensile properties due to abrasion was highest in the weft direction. It is also found that the higher mass loss due to abrasion does not always result in a greater loss in ultimate tensile properties. The composition and the structure of the weft yarn significantly affected the extent of the mass loss and the loss in ultimate tensile properties during abrasive damage.Originality/valueThe impact of abrasive damage in terms of mass loss and loss in tensile strength along the different directions of denim fabric has not been explored till date. Abrasion of fabric can be done both in multi-direction (Lissajous motion) as well as in uni-direction (linear motion). The multidirectional abrasion provides a holistic or comprehensive idea of the fabric's response to the abrasive damage but does not take into consideration the fabric's anisotropic response to the abrasive damage. Most of the earlier investigation related to abrasive damage of denim fabric has been done in instruments where the motion of the abrader is multidirectional (Lissajous) in nature. For greater depth of understanding about the fabric performance under abrasive damage along the various direction (warp, weft and biased), unidirectional abrasion is conducted in this study.

Development of a Freshness Index for Fruit Quality Assessment—Using Bell Pepper as a Case Study

(1) Background: This special issue contains new developments in the field of fresh produce quality. Freshness provides the appeal for the consumer to purchase a particular horticultural produce. Freshness is a combination of size, colour, shape, flesh firmness, turgescence and glossiness without wilting, which imply that the produce has been picked only a short while ago and has not suffered any decay during harvest, transport or storage. (2) Objective: The objective of the present work was to develop potential freshness indices. The indices are based on non-invasive, real-time measurements, using changes in surface appearance after harvest, using Bell pepper as the most difficult model. (3) Methods: The selection criteria were a dramatic change in values over 14 days of storage at 17 °C, and either a consistent decrease or increase without peaks and troughs. Only two (out of five) non-invasive techniques were selected, i.e., surface glossiness, measured non-destructively using a luster sensor (type CZ-H72 from Keyence Co., Osaka, Japan) and light reflection spectra, recorded by a spectrometer, whereas the three techniques fruit firmness (penetrometer), colorimeter (e.g., Minolta) and false colour images (profilometer) were excluded. (4) Results: The first technique based on fruit glossiness provides luster values depending on fruit colour. Green Bell pepper fruit with a Fresh Index in excess of 463–490 a.i. can be classified as fresh, and similarly of 525–565 a.i. for yellow and 486–502 a.i. for red pepper fruit. This first Freshness index dropped, indicating a lesser freshness, to less than 100 a.i. after 14 days storage, irrespective of fruit colour, thereby providing a suitable wide, ca. 5-fold, range of parameterization. The second index is based on the difference between the light reflectance peaks at 630–633 nm and at 500 nm, also measured perpendicular to the convex fruit side. These percentage values decreased from >40% with fresh red and yellow Bell pepper to ca. 20% after 14 days storage; similarly, these percentages decreased from ca. 16% to ca. 8% in green pepper fruit, in both cases by a twofold factor. Overall, a third Freshness index could be a combination of luster values larger than 470 a.u. and >40% difference of the light reflectance between 630 nm and 500 nm. (5) Conclusions: Two viz three freshness indices are proposed and thresholds elaborated for Bell pepper fruit. The analysis showed that both indices viz technologies, luster and light reflection spectra, require colour differentiation, i.e., a specific index for yellow, red and green Bell pepper fruit.

Revisiting the fabrication of superhydrophobic aluminum surfaces and their use as soft substrates for droplet manipulation

Superhydrophobic aluminum (Al) surfaces are desired in many applications and have been widely studied, but some fundamental issues in their fabrication are not yet fully understood. In this study, commonly used HCl solution and organic acid/sulfur reagents were employed for clarifying the phenomena in etching and composition modification. An unstable layer was revealed after HCl etching, which was removable with water flushing, and this layer, consisting of scattered AlCl3/Al2O3 particles surrounded by Al2O3 plates with cracks, caused changes in surface appearance from bright to dark. A complete change in surface color corresponded to sufficient etching, and hence, this visible phenomenon could be used to confirm the shortest etching time for achieving desirable superhydrophobicity. Composition modification with dodecanethiol and myristic acid also modified the microstructure through a slight etching mechanism and a synergistic effect was found with the use of their mixture, which led to the finest grains and most abundant carbon chains on the final surfaces. Consequently, the best superhydrophobicity was revealed in static and dynamic experiments with droplets. Finally, using the advantage of flexibility, a superhydrophobic Al sheet was demonstrated to be suitable for subjecting droplets to controlled rolling and coalescence, which could be meaningful for many droplet-related studies.

Measuring Weathering and Nanoparticle Coating Impact on Surface Roughness of Natural Stones

ABSTRACTThe surface texture of a stone represents a sensitive parameter in evaluating its conservation state. In monuments and sculptures, in fact, external agents continuously alter the appearance of stones, determining peculiar weathering patterns and modifying properties such as retention of water and particles, interaction with light, color, and finishing. The application of protective coatings also determines changes in surface appearance of a stone, usually evaluated and monitored by color change tests. Surface metrology methods offer the possibility to quantify these changes, evaluating the impact of external agents (natural, i.e. weathering, and artificially, i.e. protective coatings) on natural stones. In this research, we demonstrate the potential of surface areal measurements in describing the evolution of weathering processes and the effects of protective treatments on porous stone materials. The obtained results suggest that the extent of the modifications is related to the scale of observation (small- vs. large-scale undulations, i.e. roughness and waviness, respectively), with an overall increase of surface roughness as the weathering proceeds. Unexpectedly, coatings based on nanoparticle dispersions increase the topographic height parameters, due to the absence of a homogeneous film.

Acid Pickling/polishing of AZ31 Magnesium Alloy

This article reports a new chemical bath for preparing a mirror-like surface of AZ31 Mg alloy. In order to find an appropriate chemical polishing solution, four different acidic solutions of sulphuric acid, nitric acid, acetic acid and a specially designed mixture of nitric acid and acetic acid were investigated in view of the changes in surface appearance, roughness and dissolution rate of AZ31 Mg alloy. The surface scales on AZ31 Mg alloy were readily removed by all the acidic solutions, but a reflective surface was produced only by etching in the specially designed solution, and only after a specific etching time. The surface roughness increased with etching time in sulphuric acid, nitric acid, and acetic acid, but it lowered after a specific etching time in the specially designed mixture of nitric acid and acetic acid. Dissolution rate of the alloy in the specially designed mixture of nitric acid and acetic acid appeared to be more than twice than that in separate nitric acid or acetic acid. In this work, we recommend the mirror-like surface of AZ31 Mg alloy obtained by polishing for an optimum time in a mixture of nitric acid and acetic acid for following surface finishings, chemical conversion coating, electroplating, electrophoretic painting and anodizing treatment.

Antimicrobial activity of prodigiosin is attributable to plasma-membrane damage

The bacterial pigment prodigiosin has various biological activities; it is, for instance, an effective antimicrobial. Here, we investigate the primary site targeted by prodigiosin, using the cells of microbial pathogens of humans as model systems: Candida albicans, Escherichia coli, Staphylococcus aureus. Inhibitory concentrations of prodigiosin; leakage of intracellular K+ ions, amino acids, proteins and sugars; impacts on activities of proteases, catalases and oxidases; and changes in surface appearance of pathogen cells were determined. Prodigiosin was highly inhibitory (30% growth rate reduction of C. albicans, E. coli, S. aureus at 0.3, 100 and 0.18 μg ml−1, respectively); caused leakage of intracellular substances (most severe in S. aureus); was highly inhibitory to each enzyme; and caused changes to S. aureus indicative of cell-surface damage. Collectively, these findings suggest that prodigiosin, log Poctanol–water 5.16, is not a toxin but is a hydrophobic stressor able to disrupt the plasma membrane via a chaotropicity-mediated mode-of-action.

Innovative use of biologically produced ferric sulfate for machining of copper metal and study of specific metal removal rate and surface roughness during the process

The biologically produced ferric sulfate (in the form of bacterial culture supernatant) was used for machining of copper metal workpiece. A 27.04mg/hcm2 average specific metal removal rate was achieved during oxidation of copper workpiece. The leaching performance of culture supernatant was comparable to that of microbial cells indicating that an indirect non-contact leaching mechanism is predominant for metal solubilization. The surface of copper workpiece was analyzed by scanning electron microscopy before and after oxidation. The changes in surface appearance were found during oxidation of copper. Also the change in surface roughness was observed during machining process. The quality of the surface produced is a very important aspect of the performance of the manufacturing process. Therefore the present study characterizes an effect of various physicochemical parameters on specific metal removal rate and surface roughness. An increasing concentration of FeSO4, shaking speed and volume of culture supernatant showed pronounced effect on metal removal and surface roughness. At the same time an application of varying temperatures showed little effect.

High power breakdown testing of a photonic band-gap accelerator structure with elliptical rods

An improved single-cell photonic band-gap (PBG) structure with an inner row of elliptical rods (PBG-E) was tested with high power at a 60 Hz repetition rate at X-band (11.424 GHz), achieving a gradient of $128\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ at a breakdown probability of $3.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ per pulse per meter at a pulse length of 150 ns. The tested standing-wave structure was a single high-gradient cell with an inner row of elliptical rods and an outer row of round rods; the elliptical rods reduce the peak surface magnetic field by 20% and reduce the temperature rise of the rods during the pulse by several tens of degrees, while maintaining good damping and suppression of high order modes. When compared with a single-cell standing-wave undamped disk-loaded waveguide structure with the same iris geometry under test at the same conditions, the PBG-E structure yielded the same breakdown rate within measurement error. The PBG-E structure showed a greatly reduced breakdown rate compared with earlier tests of a PBG structure with round rods, presumably due to the reduced magnetic fields at the elliptical rods vs the fields at the round rods, as well as use of an improved testing methodology. A post-testing autopsy of the PBG-E structure showed some damage on the surfaces exposed to the highest surface magnetic and electric fields. Despite these changes in surface appearance, no significant change in the breakdown rate was observed in testing. These results demonstrate that PBG structures, when designed with reduced surface magnetic fields and operated to avoid extremely high pulsed heating, can operate at breakdown probabilities comparable to undamped disk-loaded waveguide structures and are thus viable for high-gradient accelerator applications.

Corrosion Behavior of Type 304L Stainless Steel in UREX+ Nitric Acid Solutions Using Immersion and Rotating Cage Techniques

UREX+ is an advanced separation process for treatment of spent nuclear fuels where the separation of radioactive ions is accomplished in centrifugal contactors made of Type 304L (UNS S30403) stainless steel. This research work was focused on corrosion behavior of Type 304L (UNS S30403) stainless steel at experimental parameters simulating the environment of a centrifugal contactor during its operation. Corrosion studies were completed using the immersion and rotating cage (RC) corrosion techniques. In this investigation corrosion coupons were exposed to three different nitric acid (HNO3) solutions. Corrosion rates in 5 M HNO3 and 5 M HNO3 + 0.1 M hydrofluoric acid (HF) + 0.1 M Zr4+ solutions were lower than 0.0127 mm/y. The relatively high corrosion rates in 5 M HNO3 + 0.1 M HF solutions were reduced by the addition of Zr4+ ions that behave as corrosion inhibitors forming Zr-F complex ions. The inhibitor efficiency of Zr4+ ions reached an average of 99.61%. Corrosion results were mainly a function of the corrosive characteristic of each solution and lesser degree dependent on solution temperature. The effect of wall shear stresses generated in the rotating cage technique was not observed in these tests. Corrosion test results also were discussed based on surface chemistry, electrochemical impedance spectroscopy (EIS) Nyquist plots, and surface appearance changes, which included microstructural analysis.

Three-dimensional characterisation of surface texture for road stones undergoing simulated traffic wear

This paper describes a robust methodology for inspection of the changing surface texture of road stones as they undergo simulated traffic polishing. Three-dimensional measurements of surface relief are made at five discrete levels of wear, corresponding to five levels of friction. The advantages of measurement in three dimensions are explored, observations are made about the change in surface appearance and the surface is characterised at each stage using a standard areal roughness parameter.

Biomachining rates of various metals by Acidithiobacillus thiooxidans

The evaluation of a potential of a microorganism for the biomachining technology is conducted in the current study. As the fundamental step, the specific metal removal rates (SMRR) of copper, nickel and aluminium in use of different level of cell concentration of Acidithiobacillus thiooxidans(At. thiooxidans) and the associated supernatant are investigated and compared. The specific metal removal rate is a key criterion to characterise any industrial machining process. The dissolution of metals by this chemolithotrophic bacteriumcan occur either by direct or indirect mechanism. The extracellular supernatant showed higher machining rate than the cells in solution. The aspect ratio in micropattern machining is examined for copper and nickel. The behaviour of aluminium in micromachining was unsatisfactory. The scanning electron microscopy was used to analyse the surface of copper workpiece before and after oxidation. During the oxidation of copper the changes in surface appearance and surface roughness were observed.

Factors Associated With Fouling in the Process Industry

This study evaluates the feasibility of using surface coatings on commonly used process surfaces to minimize/delay the effect of fouling. The materials considered here are stainless steel and copper with AgION and Xylan coatings. Sample plates were placed vertically in test tanks and then exposed to untreated lake water for various time periods. Results are presented that compare surface roughness over time. Additional results show transient deposit weight gain. The progressive change in surface appearance with increasing immersion times is also presented and gives a visual representation of the surface at a specific time. This review includes observations on the fouling of coated process surfaces. All coated samples showed some deposit accumulation with no change in surface appearance for the periods of immersion considered. Conclusions and observations regarding the material coatings for surfaces that are commonly used in designs where fouling may be a concern are presented here. Fouling rates, transient surface roughness values, and transient photographs of the frontal surfaces of the materials are given for typical conditions.

The Shrinkage and Change in Surface Appearance of the Blended Knit Fabrics of Angora Rabbit Hair and Wool in Washing and Drying

The Shrinkage and Change in Surface Appearance of the Blended Knit Fabrics of Angora Rabbit Hair and Wool in Washing and Drying

RILEM TC190-SBJ: development of recommendations on novel durability test methods for wet-applied curtain-wall sealants

The paper discusses the work carried out over the past 7 years within RILEM Technical Committee 190-SBJ Service Life Prediction of Sealed Building and Construction Joints towards the development of RILEM Technical Recommendations (RTR) on durability test methods for wet-applied (gun-grade) curtain-wall sealants. This paper is published along with the two draft RTR methods to provide some insight into the discussions within the committee during the development and early evaluation of both methods. The two draft RTR methods define test and evaluation protocols for accelerated artificial weathering and natural outdoor weathering. Both draft RTR methods are based on a novel test specimen configuration that allows simultaneous exposure of the sealant to compression and extension during movement cycles. Because of the special test joint configuration, the sealant is exposed to variable extension and compression amplitudes along the joint axis, allowing an evaluation of the effect of different movement amplitudes on the sealant when taking weatherability considerations into account. The results of the initial evaluations indicate that the test methods are capable of differentiating between products with regard to their resistance to accelerated or outdoor weathering and mechanical cycling. The type of failure and the changes in surface appearance observed during the test regimes are similar to those observed in actual service conditions. It is hoped that exposure studies based on these two new RTR methods will provide the underpinnings for the development of future ISO and ASTM durability test standards for building sealants.

Hygrothermal effects on properties of highly conductive epoxy/graphite composites for applications as bipolar plates

The hygrothermal effects on mechanical, thermal, and electrical properties of highly conductive graphite-based epoxy composites were investigated. The highly conductive graphite-based epoxy composites were found to be suitable for applications as bipolar plates in proton exchange membrane (PEM) fuel cells. The hygrothermal aging experiments were designed to simulate the service conditions in PEM fuel cells. Specifically, the composite specimens were immersed in boiling water, aqueous sulphuric acid solution, and aqueous solution of hydrogen peroxide. The water uptake, changes in surface appearance and dimensions, glass transition behavior and thermal stability, and electrical and mechanical properties were evaluated. The water uptake at short time increased linearly with the square root of time as in linear Fickian diffusion. The presence of graphite significantly reduced both the rate and extent of water uptake. No discernible changes in specimen dimensions, surface appearance, and morphology of the composites were observed. The electrical conductivity and mechanical properties remained almost unchanged. The wet specimens showed slight reduction of glass transition temperature ( T g) due to plasticization of epoxy networks by absorbed water, while the re-dried specimens showed small increase of T g. The composites maintained high electrical conductivity of about 300–500 S cm −1 and good mechanical properties and showed thermal stability up to 350 °C.

Experimental study on sheet metal bending with medium-power diode laser

In an experimental study of laser sheet bending, a 160 W diode laser is used for two-dimensional sheet bending of low-carbon steel. The variables investigated include metal sheet thickness, laser scan speed, laser power, laser beam width, and laser scan pass number. Bend surface appearances are also analysed.The laser sheet bend results demonstrate that a 940 Nm diode laser is an effective tool for laser forming of carbon steel sheets. No additional surface coating was required. The buckling mechanism may be the main source contributing to the large angle of bend found for the laser-beam-width to sheet-thickness aspect ratio close to 4; for a laser-beam-width to sheet-thickness aspect ratio of less than 2, both temperature gradient and buckling mechanisms contributed to the lower bend angles. The laser beam width study showed that, for the given material thickness range and laser beam profile, the maximum bend angle depends mainly on the material thickness, not the power intensity distribution across the bend line. However, a more evenly distributed laser beam gave the same bend angle with less material property and surface appearance changes. For obtaining the same bend angle, less laser line energy was required if a higher laser scan speed was applied, except for the extreme high-line energy level. Also, multi-path bend strategies may be preferred for maximizing the total bend angle as well as reducing bend surface morphology changes.

Fouling surface finish evaluation

Fouling of a surface takes place as the result of a series of complex reactions that cause deposits to form on process surfaces. For many conditions, fouling can be reduced but not necessarily eliminated. The materials considered here are: carbon steel, stainless steel, and aluminium with typical finishes. Sample plates were placed vertically in tanks and exposed to untreated lake water for various time periods. Results are presented that compare surface roughness over time, for the materials/surfaces considered. The progressive change in surface appearance with increasing immersion times is also presented. Stainless steel samples showed a relatively small change in surface appearance for most periods of immersion, with a small increase in surface deterioration for increasing immersion times. Brite aluminum, an aluminium alloy with an anodized surface film, performs similar to stainless steels. Cold rolled carbon steel has the largest variation of surface appearance over time. This review includes observations on fouling and process surface materials/finishes. Conclusions and observations regarding the materials that are commonly used in designs when fouling may be a concern are presented here. Photographs of material frontal surfaces and transient surface roughness are given for a variety of surfaces.

A Cross-species Comparison of Facial Morphology and Movement in Humans and Chimpanzees Using the Facial Action Coding System (FACS)

A comparative perspective has remained central to the study of human facial expressions since Darwin's [(1872/1998). The expression of the emotions in man and animals (3rd ed.). New York: Oxford University Press] insightful observations on the presence and significance of cross-species continuities and species-unique phenomena. However, cross-species comparisons are often difficult to draw due to methodological limitations. We report the application of a common methodology, the Facial Action Coding System (FACS) to examine facial movement across two species of hominoids, namely humans and chimpanzees. FACS [Ekman & Friesen (1978). Facial action coding system. CA: Consulting Psychology Press] has been employed to identify the repertoire of human facial movements. We demonstrate that FACS can be applied to other species, but highlight that any modifications must be based on both underlying anatomy and detailed observational analysis of movements. Here we describe the ChimpFACS and use it to compare the repertoire of facial movement in chimpanzees and humans. While the underlying mimetic musculature shows minimal differences, important differences in facial morphology impact upon the identification and detection of related surface appearance changes across these two species.

Experimental results obtained with proposed RILEM durability test method for curtain wall sealants

Over the past six year, RILEM TC 139-DBS has been developing a RILEM Technical Recommendation (RTR) for a durability test method for curtain wall joint sealants. As the committee started to converge towards the final test method, the importance of evaluating the behaviour of a set of sealants under comparative conditions became apparent in order to validate the proposed durability test method. This paper provides a summary of the results obtained with the procedure described in the April 1999 draft. The study shows that the test method is able to differentiate between products with regard to their resistance to accelerated ageing and mechanical cycling. The type of failure and the changes in surface appearance obseved during the test regime are similar to those observed in actual service conditions. Sealant degradation resulting from the durability cycles was slower than had been anticipated for most sealant systems. The dynamic conditioning procedure (movement during cure) reduced joint durability for some of the tested products, but increased it for others. The fatigue cycling clearly accelerated sealant degradation.

Reproducibility in the Assessment of Caries Lesion Behaviour: A Comparison between Conventional Film and Subtraction Radiography

The purpose of this study was to compare reproducibility in the assessment of caries lesion behaviour in digital subtraction images and conventional radiographs. Ninety–seven pairs of conventional film bite–wings were included. The radiographs had been taken with a Kwik–Bite filmholder without further standardisation. The selection criterion was that at least one surface imaged in a bite–wing pair should show progresssion of a caries lesion from the first exposure to the second. The time interval between the bite–wings was 1–2 years. The radiographs were scanned into a personal computer and the two images from the same patient subtracted. Seven observers scored the subtraction images and the conventional films. The scale was based on no change/ change in surface appearance scored in the following categories: 0 = no change; 1 = development of a new caries lesion in enamel; 2 = development of caries lesion in enamel and dentine/progression of an existing enamel lesion into dentine/progression of a dentinal lesion further into dentine; 3 = development of secondary caries; 4 = new filling/change of filling/extension of filling. Cohen’s κ coefficients were calculated for intra– and inter–observer agreement for the two radiographic methods separately. The κ value served as the statistical sampling unit for testing differences between the two methods (Wilcoxon’s test for ranked pairs). The average intra–observer κ value was 0.875 (range 0.775–0.958) for the subtraction images and 0.758 (range 0.560–0.890) for the conventional radiographs. The difference was statistically significant (p<0.05). For inter–observer agreement, the κ values were lower than for intra–observer agreement. The average value was 0.678 (range 0.485–0.754) for the subtraction images and 0.701 (range 0.497–0.817) for the conventional radiographs (p>0.1). This study suggests a new way of comparing reproducibility in terms of κ values between diagnostic methods in clinical studies where accuracy cannot be evaluated. The subtraction method may be useful in the assessment of caries lesion behaviour in the clinic.