ISO Test Research Articles

Standardized Loads Acting in Knee Implants

The loads acting in knee joints must be known for improving joint replacement, surgical procedures, physiotherapy, biomechanical computer simulations, and to advise patients with osteoarthritis or fractures about what activities to avoid. Such data would also allow verification of test standards for knee implants. This work analyzes data from 8 subjects with instrumented knee implants, which allowed measuring the contact forces and moments acting in the joint. The implants were powered inductively and the loads transmitted at radio frequency. The time courses of forces and moments during walking, stair climbing, and 6 more activities were averaged for subjects with I) average body weight and average load levels and II) high body weight and high load levels. During all investigated activities except jogging, the high force levels reached 3,372–4,218N. During slow jogging, they were up to 5,165N. The peak torque around the implant stem during walking was 10.5 Nm, which was higher than during all other activities including jogging. The transverse forces and the moments varied greatly between the subjects, especially during non-cyclic activities. The high load levels measured were mostly above those defined in the wear test ISO 14243. The loads defined in the ISO test standard should be adapted to the levels reported here. The new data will allow realistic investigations and improvements of joint replacement, surgical procedures for tendon repair, treatment of fractures, and others. Computer models of the load conditions in the lower extremities will become more realistic if the new data is used as a gold standard. However, due to the extreme individual variations of some load components, even the reported average load profiles can most likely not explain every failure of an implant or a surgical procedure.

Assessment of the Activity of Photocatalytic Paint Using a Simple Smart Ink Designed for High Activity Surfaces

The use of an acid violet 7 (AV7) smart ink to assess the activity of photocatalytic paint is demonstrated. A linear correlation is established between the change in oxidized dye concentration, as measured by diffuse reflectance, and the change in the green component of the RGB color values, obtained using a portable hand-held scanner, suggesting that such tests can be monitored easily using an inexpensive piece of hand-held office equipment, as opposed to an expensive lab-based instrument, such as a diffuse reflectance UV/vis spectrophotometer. The bleaching of the AV7 follows first order kinetics, at a rate that is linearly dependent upon the UVA irradiance (0.30-3.26 mW cm(-2)). A comparison of relative rate of bleaching of the AV7 ink with the relative rate of removal of NOx, as determined using the ISO test (ISO 22197-1:2007), established a linear relationship between the two sets of results and the relevance of this correlation is discussed briefly.

Kajian Penambahan Gambir sebagai Bahan Penyamak Nabati terhadap Mutu Kimiawi Kulit Kambing

Gambier contains tannin which functions as vegetable tanning material . This study aimed to determine , the gambier addition to produces the best chemical quality leather according to Indonesian National Standard chemical quality goatleather ( SNI 06-0463-1989 ). The method was used experimental method randomized block design , which consists of 5 treatments with 4 replications . Treatment of this study was added the gambier percentage ( %), each treatment consisting of : treatment A : 15% , B : 20%, C : 25% , D : 30%, and E : 35% . The variables were measured water content , oil/fat content , water-soluble substances content , levels of substances rawhide , levels of insoluble ash in the water , levels of tanning substances ( tannins) bound and the tanning degree . The results showed a significantly different effect ( P < 0.05) to decrease water content , levels of substances rawhide , levels of substances soluble in water and increasing tanning degree and did not differ significantly (P > 0.05) oil/fat content , ash content and levels of tanning substances ( tannins) bound . The conclusion of this study was the addition of 25% was the best gambier percentage , with 17.06 ±0.15% water content, the fat/oil 7.69±1.24%, the levels of water-soluble substances 4.16±0.99%, levels of substances rawhide 42.47±6.39%, 0.99±0.03% levels of insoluble ash in the water, levels of tanning substances (tannins) bound 27.63±2.75% and 65.46% tanning degree, which all meet the quality standard ISO test 06-0994-1989 and SNI No.0253-2009.

Accreditation of a forensic genetics laboratory in Italy

Although in Italy DNA analysis is used since the beginnings, the introduction of a specific legislation had a very important impact for the quality of the results. Only authorized laboratories can now implement the database with genetic profiles; these labs have to follow ISO/IEC standard and according to the Council Framework Decision 2009/905/JHA of 30 November 2009 and the Recommendation 7 of ENFSI this standard is the ISO17025/2005 accreditation. Since December 22th 2009, ACCREDIA is the only appointed Italian Accreditation authority can issue the accreditation certificate. There is no rule to define the ISO test method for the study of DNA polymorphisms in forensics, thus each laboratory should build their own analytical system, reliable and reproducible, through its own internal validation. Here, we focus on some points of the accreditation process developed in our laboratory concerning internal validation protocol.

Mechanical properties characterization of the skin and core of a novel composite sandwich structure

This study has investigated the mechanical properties of the constituent materials of a novel structural composite sandwich panel developed for structural applications. Properly designed and carefully conducted experiments using coupon specimens following ISO and ASTM test standards were performed to characterize the flexural, tensile, compressive and shear properties of the fiber composite skins and the modified phenolic core of the composite sandwich structure. As a general behavior, the glass fiber composite skins behaved linearly elastic up to failure in both tension and compression with the tensile strength much higher than the compressive strength. The modified phenolic core behaved linearly elastic in tension but exhibited non-linear behavior in compression. The modified phenolic core material exhibited higher strength and modulus in shear and compression compared to the traditional core material systems. The improved mechanical properties of the core structure combined with the high-strength and lightweight glass fiber composite skins suggest a high potential of the novel composite sandwich panel for structural applications. Furthermore, the results of this study provide an understanding of the fundamental behavior of the constituent materials of a novel sandwich structure providing a base knowledge from which further research could continue.

환경오염공정시험기준과 KS ISO규격의 일원화에 관한 연구 - 먹는 물 및 실내공기질 -

현행 환경오염공정시험기준 중 먹는 물 수질공정시험기준과 실내공기질 공정시험기준에 대해 국제규격에 부합화된 KS ISO규격과의 일원화에 관해 연구하였다. KS규격 23,000여종을 대상으로 먹는 물 및 실내공기질관련 KS 규격을 조사하였다. 환경분야관련 KS규격은 KS I로 분류되며, 총 653종으로 조사되었으며, 이중 국제규격에 부합화된 KS I 규격은 583종으로 조사되었다. 먹는 물 수질공정 시험기준은 총 100개 기준을 대상으로 ISO/TC 147 "Water Quality" 관련 KS 규격 총 232종을 비교 검토하였으며, 실내공기질 공정시험기준은 "ISO/TC 146 "Air Quality" 관련 KS 규격 총 95종 규격을 비교 검토하였다. 문헌검토와 비교시험을 통해 먹는 물 및 실내공기질 공정시험기준과 일원화 가능한 국제규격에 부합화된 KS규격 연구결과 먹는물수질공정시험 100개 기준 중 사전일원화 완료 23개 기준, 일원화 가능 29개 기준, 일원화 불가 12개 기준, 대응 규격 없는 기준이 36개로 평가되었으며, 실내공기질 공정시험기준 17개 기준 중 사전일원화 완료 1개 기준, 일원화 가능 3개 기준, 일원화 불가 3개 기준, 대응규격 없는 기준이 10개 기준으로 평가되었다. Our study researched on unification of KS I ISO standard harmonized with ISO and Official Test Method enacted by Korean Ministry of Environment-drinking water and indoor air quality. We reviewed KS methods related to drinking water and indoor air quality for about 23,000 KS methods. KS methods related environmental field are classified as KS I, total 635 methods and 583 KS I methods were harmonized with ISO. For Environmental Standard methods for drinking water, 100 methods were reviewed according to 232 KS methods related to ISO/ TC 147 "Water Quality". Environmental Standard methods for indoor air quality were reviewed according to 95 KS standard methods related to ISO/TC 146 "Air Quality". By reviews and comparison tests for unifiable ES for drinking water and indoor air quality with KS methods harmonized with ISO, it was evaluated that for 100 ES methods for drinking water, 23 ES methods were unification complete, 29 ES methods were unification possible, 12 ES methods were unification impossible, no corresponding methods were found in KS I ISO for 36 ES methods and for 17 ES methods for indoor air quality,1 ES methods were unification complete, 3 ES methods were unification possible, 3 ES methods were impossible, no corresponding methods were found in KS I ISO for 10 ES methods.

Overview of the current ISO tests for photocatalytic materials

► The 8 published ISO standards on semiconductor photocatalysis are reviewed. ► Areas covered are: air and water purification, self-cleaning, photo-sterilisation and light sources. ► Additional tests – such as stearic acid removal or photocatalyst indicator inks are suggested. The current eight published ISO standards associated with semiconductor photocatalysis are considered. These standards cover: (1) air purification (specifically, the removal of NO, acetaldehyde and toluene), (2) water purification (the photobleaching of methylene blue and oxidation of DMSO) (3) self-cleaning surfaces (the removal of oleic acid and subsequent change in water droplet contact angle), (4) photosterilisation (specifically probing the antibacterial action of semiconductor photocatalyst films) and (5) UV light sources for semiconductor photocatalytic ISO work. For each standard, the background is first considered, followed by a brief discussion of the standard particulars and concluding in a discussion of the pros and cons of the standard, with often recommendations for their improvement. Other possible standards for the future which would either compliment or enhance the current ones are discussed briefly.

An overview of the methylene blue ISO test for assessing the activities of photocatalytic films

The main features are described of the ISO published standard: 10678:2010, namely the ‘Determination of photocatalytic activity of surfaces in an aqueous medium by degradation of methylene blue’. The main underlying assumptions of the standard are considered, namely: (i) dye purity, (ii) adsorption and pH, (iii) light source, (iv) stirring and diffusion, (v) reaction mechanism and (vi) kinetics. Possible sources of errors arising form these assumptions are identified and changes to the standard's protocol suggested. The major suggested changes are: (i) a source of MB+ of known and proven on site high purity (>90%) should be used to make up the standard test solution, which should have a referenced absorbance, 0.74, at 665nm; (ii) the conditioning solution should be the same concentration as the standard test solution, (iii) the initial pH of the reaction solution should lie in the range: 5.5–6.0; (iv) a BLB UVA light with a europium-doped strontium fluoroborate or borate phosphor should be used; (v) the reaction solution should be vigorously and continuously stirred if possible; (vi) the solution height should be the minimum recommended value of 2cm, and the photoreactor cylinder i.d., 4.7cm; (vii) after the 3h irradiation the reaction solution should be left stirring overnight to check that no dye photoreductive bleaching has occurred. Application of most of these suggestions should improve considerably the standard's reported current poor percentage errors for repeatability within a lab (9.2%) and reproducibility between labs (30.6%).

Curing Depth of Light-activated Nanofiller containing Resin Composites

ABSTRACT Objective To compare the depth of cure of nanofiller containing with conventional resin composites. Materials and methods Five nanofilled and nanohybrid composites were investigated and compared with a microfilled and a microhybrid reference, using the ISO 4049 scraping test, Knoop hardness (KHN) and DC profiling. Specimens from all materials (shade A3) were activated with the same LED light source for 20s. KHN (0.25N/15s) of three specimens each, produced in split molds was measured after 24 hours dark storage on sections perpendicular to the irradiated surface at 250 µm distance along the center line and two parallel lines, 0.5 mm apart, to a depth of 3 mm. Mean KHNs of the three neighboring indentations at each level were calculated. Degree of conversion (DC) was determined on specimens as mentioned above using micro-Raman spectroscopy at 125 µm distance with three measurements at each depth level. Results The depth of cure of all materials was >2 mm when determined according to the ISO test. KHN and DC data followed second order polynomial regression lines (r2 > 0.70; p < 0.001). At 2 mm depth, the KHN of six resin composites was ≤80% of the top KHN whereas the DC of all materials was ≥86% of the maximum DC at the irradiated surface. Conclusion The ISO scraping test overemphasizes the attainable depth of cure, when compared with 80% of top KHN as arbitrarily defined curing depth. KHNs reflect the crosslink density of the polymer, whereas DC additionally includes double bond conversions not contributing to enhancement of mechanical characteristics. How to cite this article Kanehira M, Araki Y, Finger WJ, Wada T, Utterodt A, Komatsu M. Curing Depth of Light-activated Nanofiller containing Resin Composites. World J Dent 2012;3(2): 119-125.

Drinking Water Test Methods in Crisis-Afflicted Areas: Comparison of Methods Under Field Conditions

To simplify the testing of drinking water in crisis-afflicted areas (as in Kosovo in 2007), rapid test methods were compared with the standard test. For Escherichia coli and coliform pathogens, rapid tests were made available: Colilert(®)-18, P/A test with 4-methylumbelliferyl-β-D-glucoronid, and m-Endo Broth. Biochemical differentiation was carried out by Enterotube™ II. Enterococci were determined following the standard ISO test and by means of Enterolert™. Four hundred ninety-nine water samples were tested for E. coli and coliforms using four methods. Following the standard method, 20.8% (n=104) of the samples contained E. coli, whereas the rapid tests detected between 19.6% (m-Endo Broth, 92.0% concordance) and 20.0% (concordance: 93.6% Colilert-18 and 94.8% P/A-test) positive samples. Regarding coliforms, the percentage of concordant results ranged from 98.4% (P/A-test) to 99.0% (Colilert-18). Colilert-18 and m-Endo Broth detected even more positive samples than the standard method did. Enterococci were detected in 93 of 573 samples by the standard method, but in 92 samples by Enterolert (concordance: 99.5%). Considering the high-quality equipment and time requirements of the standard method, the use of rapid tests in crisis-afflicted areas is sufficiently reliable.

Fibre-in-Fibre Bioartificial Liver device: initial in vitro testing

Transplantation is the proven treatment for acute liver failure and in severe cases, affective Bioartificial Liver (BAL) support may provide a bridge to transplantation. This paper describes in vitro evaluation of a novel Fibre-in-Fibre BAL. It is a conventional fibre cartridge with three discrete compartments. Bovine blood is used to assess Oxygen transfer performance of the FIF bioreactor. The tests were carried according to ISO test protocols. Blood flow rate, number of fibre-in-fibre pairs and haemoglobin concentration, CHb are used to assess the oxygen transfer rates. The results demonstrated that the FIF bioreactor provides good gas transfer support.

Biomolecules in multilayer film for antimicrobial and easy-cleaning stainless steel surface applications

Microorganisms are able to attach to, grow on, and ultimately form biofilms on a large variety of surfaces, such as industrial equipment, food contact surfaces, medical implants, prostheses and operating rooms. Once organized into biofilms, bacteria are difficult to remove and kill, which increases the risk of cross-contamination and infection. One way to address the problem may thus be to develop antibacterial, anti-adhesion, ‘easy cleaning’ surfaces. In this study, stainless steel (SS) surfaces with antibacterial properties were created by embedding several antimicrobial peptides in a multilayer film architecture. The biocidal effect of these surfaces was demonstrated against both Gram-positive and Gram-negative bacteria according to two ISO tests. Also, coating SS surfaces with either mucin or heparin led to a reduction of S. epidermidis adhesion of almost 95% vs the bare substratum. Finally, by combining both antibacterial and anti-adhesion biomolecules in the same multilayer film, SS surfaces with better cleanability were produced. This surface coating property may help to delay the buildup of a dead bacterial layer which is known to progressively reduce exposure of the coating, leading to an undesirable decrease in the antibacterial effect of the surface.

Comparative toxicity of leachates from 52 textiles to Daphnia magna

The environmental aspects of textiles are very complex and include production, processing, transport, usage, and recycling. Textiles are made from a variety of materials and can contain a large number of chemicals. Chemicals are used during production of fibres, for preservation and colouring and they are released during normal wear and during washing. The aim of this study was to investigate the release to water of toxic chemicals from various textiles. Altogether 52 samples of textiles made from cotton (21), linen (4), cotton and linen (7), cellulose (3), synthetic fibres (7), cotton and synthetic fibres (8) and wool (2). Seven were eco-labelled. All textiles were cut into squares and placed into Petri dishes with 50 ml ISO test medium in a concentration series (4–256 cm 2/50 ml) and tested for acute toxicity to Daphnia magna. Estimated EC50s were converted into weight/volume, and 48-h EC50s ranged between <1 and >182 g/L. It was not possible to detect any difference between fibre type and toxicity (ANOVA), but a significantly higher toxicity was found for printed versus unprinted cotton and cotton/linen textiles, while the opposite was found for synthetic textiles. Eco-labelled products were evenly distributed on a toxicity scale, which means that eco-labelling in its present form does not necessarily protect users or the environment from exposure to toxic chemicals. Therefore, the results from the present study suggest that bioassays and toxicity tests should become an integrated part of textile environmental quality control programs.

Prevention of bacterial biofilms by covalent immobilization of peptides onto plasma polymer functionalized substrates

In this study, robust antibacterial coatings were created on stainless steel through the covalent grafting of antibacterial peptides onto an organic–polymeric interlayer deposited by RF-glow discharge plasma. X-Ray photoelectron spectroscopy was used to characterize and optimize the two steps of the coating process. The biocidal activity of these surfaces was demonstrated against both Gram+ and Gram− bacteria using ISO tests. 3 to 6 log10 reductions of both Gram+ and Gram− bacterial strains were obtained compared to uncoated stainless steel and depending on the particular antibacterial peptide immobilized. Importantly the antibacterial surfaces were resistant to several cleaning conditions. The latter is significant as the stability of such antibacterial surfaces in close to real life conditions is a major concern and leaching, de-lamination, rearrangement and ageing of the coating can lead to insufficient long term biofilm resistance of the surface.

Generation of typical weather data using the ISO Test Reference Year (TRY) method for major cities of South Korea

Computer simulation of buildings and solar energy systems is being used increasingly in energy assessments and design. Simulation often requires hourly weather data. Such data sets are the Test Reference Years (TRYs), Typical Meteorological Year (TMY) and Weather Year for Energy Calculations (WYEC). Typical weather data consists of 8760 values of various selected meteorological parameters such as ambient temperature, solar radiation, relative humidity and wind velocity and are originally derived from long-term data. This paper discusses methods of selecting typical weather data, the possibility of using the cloud cover data instead of daily global radiation and describes the selection of ISO Test Reference Year (TRY) for major cities of South Korea. The ISO-15927 procedure and algorithms are explained in detail and the Finkelstein–Schafer statistic, the basic selector statistic explained. ISO TRYs for the major cities of South Korea are derived from 20 years of meteorological data recorded during the period 1986–2005. A comparison is made between the 7 sites demonstrating the link between dry-bulb temperature, solar radiation and latitude.

Understanding of scratch-induced damage mechanisms in polymers

Following the ASTM and ISO test standards, a series of scratch tests were carried out on four categories of polymers: I) ductile and strong, II) ductile and weak, III) brittle and weak, and IV) brittle and strong. The scratch damage features were characterized by using a desktop scanner for scratch visibility assessment, and optical and electron microscopes for detailed damage mechanisms investigation. Various scratch damage mechanisms were identified for the different categories of polymers. The effect of testing rate on possible alteration of scratch damage mechanisms was also studied. The stress fields experienced by the polymer during scratch were determined using three-dimensional finite element methods modeling. It is found that both the material characteristics and the complex stress state exerted on the scratched surface are responsible for the various scratch damage mechanisms observed. A generalized scratch damage mechanism map for polymers is presented. The usefulness of the above understanding for designing scratch-resistant polymers is also discussed.

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.

Aerobic biodegradation of polyethylene glycols of different molecular weights in wastewater and seawater

In order to distinguish between aerobic biodegradation of synthetic polymers in fresh and seawater, polyethylene glycols (PEGs) were systematically and comparatively investigated in inocula from municipal wastewater and seawater aquarium filters for the first time. The molecular weight (MW) of the PEGs, (HO(CH 2CH 2O) n H, n = 3–1350) as representatives of water-soluble polymers, ranged from 250 to 57,800 Da. The biodegradation was observed by removal of dissolved organic carbon and carbon dioxide production by applying standardized ISO and OECD test methods. Specific analyses using liquid chromatography mass spectrometry (LC–MS) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) were performed. All PEGs selected were completely biodegradable in freshwater media within 65 d. PEGs with an MW up to 14,600 Da have a similar degradation pathway which is characterized by gradual splitting of C 2-units off the chain resulting in formation of short-chain PEGs. In artificial seawater media, full biodegradation of PEGs up to 7400 Da required more time than in freshwater. PEGs with MW 10,300 and 14,600 Da were only partially degraded whereas PEGs with MW 26,600 and 57,800 Da were not degraded for a period of 135 d. The biodegradation pathway of PEG 250 and PEG 970 in seawater is similar to that for freshwater. For PEGs having an MW from 2000 to 10,300 Da, the degradation pathway in seawater differs from the pathway of the shorter PEGs.

Correction of Sampler-to-Sampler Comparisons Based on Aerosol Size Distribution

This article explains a simple method for correcting a sampler-to-sampler ratio for changes in size distribution by computing a bias factor that relates the measured ratio with a ratio determined from equations that describe the collection efficiency curves of the samplers while taking size distribution into account. Laboratory trials were conducted to determine whether the resulting bias factor is independent of aerosol size distribution. During these studies, a 3-piece cassette and respirable cyclone were compared with an inhalable sampler in both a still-air chamber and a moving-air chamber operated at 0.2 m/sec and 1.0 m/sec. An ISO test dust of various size fractions was generated to produce an aerosol with mass median aerodynamic diameter ranging from 1.4 μm to 10.1 μm. An organic dust consisting of ground grain material was also applied to the still-air chamber to demonstrate differences between dust types. Results showed that the bias value was significantly different between dust types for both the cyclone/ inhalable (p=0.001) and cassette/inhalable (p=0.033) comparisons but was not different between wind conditions for either comparison. All but one comparison had insignificant slopes when comparing the bias value with median diameter, indicating that the bias value could be used to correct for size distributions in most conditions. However, bias values determined when comparing the cyclone with the inhalable sampler in the still-air condition produced a positive slope for median diameters less than 4μm(p=0.008). Further research is needed to determine why the actual cyclone/inhalable ratio decreases relative to the expected ratio as the proportion of respirable particles increases. These results suggest that, for most conditions, the size-distribution compensation can be applied to sampler-to-sampler correlations provided that the original comparison was performed with the same dust type.

Anaerobic inhibition and biodegradation of antibiotics in ISO test schemes

Municipal sewage is the main exposure route for antibiotics that are used in human medical care. Antibiotics that adsorb to the primary sludge and/or sur-plus activated sludge will enter the anaerobic digesters of municipal sewage treatment plants. Here anaerobic biodegradation or inhibition of anaerobic bacteria resulting in a disturbance of the process might occur. ISO standards 13641 (2003) and 11734 (1999) were used for assessing the anaerobic inhibition of 16 and the anaerobic biodegradability of 9 antibiotics respectively. Digestion sludge from a municipal sewage treatment plant (1 g/l d.s.) was used as inoculum in both tests. In ISO 13641 (2003) most antibiotics showed only moderate inhibition effects after a 7 day incubation period, with EC 50 values between 24 mg/l and more than 1000 mg/l (equal to mg/g d.s.). In contrast, metronidazol was decisively toxic to anaerobic bacteria with an EC 50 of 0.7 mg/l. In the anaerobic degradation tests according to ISO standard 11734 (1995), only benzylpenicillin showed certain ultimate biodegradation after 60 days and most antibiotics inhibited the digesting sludge in the respective parallel tested inhibition controls. Thus the inhibition of anaerobic bacteria by antibiotics observed in the degradation tests was higher than expected from the results of the inhibition tests. The possible explanations are that distinct substrates are used (yeast extract versus sodium benzoate), that the digestion sludge loses activity during the washing steps performed for the degradation tests and that the exposure time in the degradation tests was 8 times longer than in the inhibition test.