4.1 This test method is useful for assessing the cytotoxic potential of new materials and formulations and as part of a quality control program for established medical devices and components.4.2 This test method assumes that assessment of cytotoxicity provides useful information to aid in predicting the potential clinical applications in humans. Cell culture methods have shown good correlation with animal assays and are frequently more sensitive to cytotoxic agents.4.3 This cell culture test method is suitable for incorporation into specifications and standards for materials to be used in the construction of medical devices that are to be implanted into the human body or placed in contact with tissue fluids or blood on a long-term basis.4.4 Some biomaterials with a history of safe clinical use in medical devices are cytotoxic. This test method does not imply that all biomaterials must pass this assay to be considered safe for clinical use (Practice F748).1.1 This test method is appropriate for materials in a variety of shapes and for materials that are not necessarily sterile. This test method would be appropriate in situations in which the amount of material is limited. For example, small devices or powders could be placed on the agar and the presence of a zone of inhibition of cell growth could be examined.1.1.1 This test method is not appropriate for leachables that do not diffuse through agar or agarose.1.1.2 While the agar layer can act as a cushion to protect the cells from the specimen, there may be materials that are sufficiently heavy to compress the agar and prevent diffusion or to cause mechanical damage to the cells. This test method would not be appropriate for these materials.1.2 The L-929 cell line was chosen because it has a significant history of use in assays of this type. This is not intended to imply that its use is preferred, only that the L-929 is an established cell line, well characterized and readily available, that has demonstrated reproducible results in several laboratories.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

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5.1 This test method is intended to be used in specifications where porosity of cellular plastics has a direct bearing on their end use. For example, for thermal insulation applications, a high percentage of closed cells is necessary to prevent escape of gases and to promote low thermal conductivity. In flotation applications, high closed-cell content generally reduces water absorption.5.2 Before proceeding with this test method, reference shall be made to the specification of the material being tested. Any test specimen preparation, conditioning, or dimensions, or both, and testing parameters covered in the materials specification shall take precedence over those mentioned in this test method. If there are no material specifications, then the default conditions apply.1.1 This test method covers cellular plastics, which are composed of membranes or walls of polymer separating small cavities or cells. These cells may be interconnecting (open cell), non-connecting (closed cell), or any combination of these types. This test method determines numerical values for open cells. It is a porosity determination, measuring the accessible cellular volume of a material. The remaining volume is that occupied by closed cells and cell walls. Since any conveniently sized specimen is typically obtained by some cutting operation, a fraction of the closed cells will be opened by specimen preparation and will be included as open cells, (see Note 2).1.2 This test method provides good accuracy on predominantly highly open-celled materials. By not accounting for closed cells that were opened during specimen preparation, the accuracy decreases as the closed cell content increases and as the cell size increases.1.3 The values as stated in SI units are to be regarded as the standard. The values in parentheses are given for reference only.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.NOTE 1: This test method and ISO 4590 use the same basic principles but are significantly different in experimental detail.NOTE 2: Two procedures for correcting for cells opened during specimen preparation are described in Appendix X1.1.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 加购物车

5.1 Knowledge of extractives from flexible barrier materials may serve many useful purposes. A test cell constructed as described in this practice may be used for obtaining such data. Another test cell has been found equivalent to the one described in this practice. See the appendix for the source of the alternate cell.5.2 United States Federal Regulations 21CFR 176.170 (d)(3), 21CFR 177.1330 (e)(4), 21CFR 177.1360 (b), 21CFR 177.1670 (b), and 21CFR Appendix VI (b) cite this standard practice as the basis for determining the amount of extractables from the surface of a package or multilayer film or modified paper in contact with food. In some cases, it is the only practice defined for this purpose. No alternative detail is given in the regulations for conducting extractions.5.3 Test Method D4754 is not an equivalent to this test method. It is for two-sided extraction of films having the same material on both of the exposed surfaces of the film.1.1 This practice covers the construction of test cells which may be used for the extraction of components from flexible barrier materials by suitable extracting liquids, including foods and food simulating solvents.1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 加购物车

4.1 This practice is useful for assessing cytotoxic potential both when evaluating new materials or formulations for possible use in medical applications, and as part of a quality control program for established medical materials and medical devices.4.2 This practice assumes that assessment of cytotoxicity potential provides one method for predicting the potential for cytotoxic or necrotic reactions to medical materials and devices during clinical applications to humans. In general, cell culture testing methods have shown good correlation with animal assays when only chemical toxicities are being considered.NOTE 1: The results obtained using this method may not predict in vivo behavior which can be influenced by multiple factors such as those arising from site of application or physical properties that may result from design and fabrication.4.3 This cell culture test method is suitable for adoption in specifications and standards for materials for use in the construction of medical devices that are intended to have direct contact with tissue, tissue fluids, or blood. However, care should be taken when testing materials that are absorbable, include an eluting or degradable coating, are liquid or gelatinous in nature, are irregularly shaped solid materials, or have a high density or mass, to make sure that the method is applicable. If leachables from the test sample are capable of diffusing through the agar layer, agarose-based methods such as Test Method F895 may be considered as an alternate method, depending on sample characteristics, or in cases where investigators wish to further evaluate the cytotoxic response of cells underlying the test sample.1.1 This practice covers a reference method of direct contact cell culture testing which may be used in evaluating the cytotoxic potential of materials for use in the construction of medical materials and devices.1.2 This practice may be used either directly to evaluate materials or as a reference against which other cytotoxicity test methods may be compared.1.3 This is one of a series of reference test methods for the assessment of cytotoxic potential, employing different techniques.1.4 Assessment of cytotoxicity is one of several tests employed in determining the biological response to a material, as recommended in Practice F748.1.5 The L-929 cell line was chosen because it has a significant history of use in assays of this type. This is not intended to imply that its use is preferred; only that the L-929 is a well characterized, readily available, established cell line that has demonstrated reproducible results in several laboratories.1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 加购物车

定价： 646元 加购物车

定价： 927元 加购物车

4.1 Mechanical drive systems operability and long-term integrity are concerns that should be addressed primarily during the design phase; however, problems identified during fabrication and testing should be resolved and the changes in the design documented. Equipment operability and integrity can be compromised during handling and installation sequences. For this reason, the subject equipment should be handled and installed under closely controlled and supervised conditions.4.2 This standard is intended as a supplement to other standards, and to federal and state regulations, codes, and criteria applicable to the design of equipment intended for this use.4.3 This standard is intended to be generic and to apply to a wide range of types and configurations of mechanical drive systems.1.1 Intent: 1.1.1 The intent of this standard is to provide general guidelines for the design, selection, quality assurance, installation, operation, and maintenance of mechanical drive systems used in remote hot cell environments. The term mechanical drive systems used herein, encompasses all individual components used for imparting motion to equipment systems, subsystems, assemblies, and other components. It also includes complete positioning systems and individual units that provide motive power and any position indicators necessary to monitor the motion.1.2 Applicability: 1.2.1 This standard is intended to be applicable to equipment used under one or more of the following conditions:1.2.1.1 The materials handled or processed constitute a significant radiation hazard to man or to the environment.1.2.1.2 The equipment will generally be used over a long-term life cycle (for example, in excess of two years), but equipment intended for use over a shorter life cycle is not excluded.1.2.1.3 The equipment can neither be accessed directly for purposes of operation or maintenance, nor can the equipment be viewed directly, for example, without radiation shielding windows, periscopes, or a video monitoring system (Guides C1572 and C1661).1.2.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.1.3 User Caveats: 1.3.1 This standard is not a substitute for applied engineering skills, proven practices and experience. Its purpose is to provide guidance.1.3.1.1 The guidance set forth in this standard relating to design of equipment is intended only to alert designers and engineers to those features, conditions, and procedures that have been found necessary or highly desirable to the design, selection, operation and maintenance of mechanical drive systems for the subject service conditions.1.3.1.2 The guidance set forth results from discoveries of conditions, practices, features, or lack of features that were found to be sources of operational or maintenance problems, or causes of failure.1.3.2 This standard does not supersede federal or state regulations, or both, and codes applicable to equipment under any conditions.1.3.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 646元 加购物车

5.1 The laboratory weathering procedure will generate data that can be used to: (1) determine whether a solid material will produce an acidic, alkaline, or neutral effluent, (2) identify solutes in the effluent that represent dissolved weathering products formed during a specified period of time, (3) determine the mass of solute release, and (4) determine the rate at which solutes are released (from the solids into the effluent) under the closely controlled conditions of the test.5.2 Data generated by the laboratory weathering procedure can be used to address the following objectives: (1) determine the variation of drainage quality as a function of compositional variations (for example, iron sulfide and calcium+magnesium carbonate contents) within individual mine-rock lithologies, (2) determine the amount of acid that can be neutralized by the sample while maintaining drainage pH ≥6.0 under the conditions of the test, (3) estimate mine-rock weathering rates to aid in predicting the environmental behavior of mine rock, and (4) determine mine-rock weathering rates to aid in experimental design of site-specific kinetic tests.5.3 The laboratory weathering procedure provides conditions conducive to oxidation of solid material constituents and enhances the transport of weathering reaction products contained in the resulting weekly effluent. This is accomplished by controlling the exposure of the solid material sample to such environmental parameters as reaction environment temperature and application rate of water and oxygen.5.4 Because efficient removal of reaction products is vital to track mineral dissolution rates during the procedure, laboratory leach volumes are large per unit mass of rock to promote the rinsing of weathering reaction products from the mine-rock sample. A comparison of laboratory kinetic tests with field tests has shown that more reaction products from mineral dissolution are consistently released per unit weight and unit time in laboratory weathering tests (9). For example, sulfate release rates observed in laboratory tests of metal-mine rock have been reported to be 3 to 8 times those for small-scale field test piles of Duluth Complex rock (10), and from 2 to 20 times those for small-scale field test piles of Archean greenstone rock (11). A greater increase is anticipated when laboratory rates are compared with field rates measured from operational waste-rock piles.5.5 Fundamental assumptions governing Options A and B of the procedure:5.5.1 Option A—An excess amount of air pumped up through the sample during the dry- and wet-air portions of the weekly cycle reduces the potential for oxidation reaction rates being limited by low-oxygen concentrations. Weekly leaches with low-ionic-strength water promote the removal of leachable mineral dissolution products produced from the previous week's weathering cycle. The purpose of the three-day dry-air portion of the weekly cycle is to evaporate some of the water that remains in the pores of the sample after the weekly leach without totally drying out the sample. Consequently, sample saturation is reduced and air flow is enhanced. During the dry-air portion of the cycle, the oxygen diffusion rate through the sample may increase several orders of magnitude as compared to its diffusion rate under more saturated conditions of the leach. This increase in the diffusion rate under near-dryness conditions helps promote the oxidation of such constituents as iron sulfide. Additionally, evaporation from the three days of dry air increases pore water cation/anion concentrations and may also cause increased acidity (for example, by increasing the concentration of hydrogen ion generated from previously oxidized iron sulfide). Increased acid generation will enhance the dissolution of additional sample constituents. As evaporation continues, the remaining water may become oversaturated with respect to some mineral phases, consequently causing them to precipitate. Some precipitated minerals are potential sources of acidity when re-dissolved (for example, melanterite, FeSO4·7H2O; and jarosite, K2Fe6(OH)12(SO4)4). Compared to the three days of dry air where the pore-water mass decreases over time, the wet (saturated)-air portion of the weekly cycle helps maintain a relatively constant mass of pore water in the sample (12). This may help promote some diffusion of weathering products (for example, re-dissolved precipitation products) in the remaining pore water without totally saturating the sample and adversely affecting oxygen diffusion.NOTE 1: Under idealized conditions (that is, infinite dilution in air and water), published oxygen diffusion rates in air are five orders of magnitude greater than in water (0.178 cm2 s–1 versus 2.5 × 10–5 cm2·s–1 at 0 and 25 °C, respectively) (13).5.5.2 Option B—In contrast to Option A, Option B protocol does not include dry air or wet air introduction to the humidity cells during the weekly cycle. Instead, Option B requires that temperature and relative humidity be maintained within a constant range by storing the cells in an environmentally controlled enclosure during the six days following the weekly 500- or 1000-mL leach. Consequently, oxygen is delivered to the cells by diffusion (and possibly advection) of ambient air, rather than by pumping. Because it lacks a dry-air cycle, more interstitial water is retained in the Option B sample than in the Option A sample during the weekly cycle. Furthermore, the interstitial water content for Option B is more constant than that in Option A during the weekly dry-air cycle. In addition, the interstitial water content for Option B is less variable over the course of testing than that in Option A (14).5.6 This test method has been conducted on metal-mine wastes to classify their tendencies to produce acidic, alkaline, or neutral effluent, and to measure the concentrations of selected inorganic components leached from the waste (2, 3, 14-16).NOTE 2: Interlaboratory testing of this method to date has been confined to mine waste rock. The method has not been tested for applicability to metallurgical processing waste. Although the method has been applied by some practitioners to finely ground metallurgical processing wastes such as mill tailings, those materials were not included in the interlaboratory testing of the method. Consequently, modifications of this method might be necessary to deal with problems associated with finely ground materials, which would make this method as written inappropriate for kinetic testing of finely ground materials. For kinetic testing of finely ground materials, please refer to the biological acid production potential method in the appendix of Test Methods E1915 or other kinetic methods accepted by the regulatory jurisdiction.5.7 The following are examples of parameters for which the scheduled weekly, semi-monthly, or monthly collected effluent may be analyzed (see 11.5.2 for suggested effluent collection frequency):5.7.1 pH, Eh (oxidation/reduction potential), and conductivity (see Test Methods D1293, D1498, and D1125, respectively, for guidance);5.7.2 Alkalinity/acidity values (see Test Methods D1067 for guidance);5.7.3 Cation and anion concentrations;5.7.4 Metals and trace metals concentrations.5.8 An assumption used in this test method is that the pH of each of the leachates reflects the progressive interaction of the interstitial water with the acid-generating or acid-neutralizing capacity, or both, of the solid material under specified laboratory conditions.5.9 This test method produces leachates that are amenable to the determination of both major and minor constituents. It is important that precautions be taken in sample collection, filtration, preservation, storage, and handling to prevent possible contamination of the samples or alteration of the concentrations of constituents through sorption or precipitation.5.10 The leaching technique, rate of leach water addition, liquid-to-solid ratio, and apparatus size may not be suitable for all types of solid material.5.11 Notable differences have been observed between Option A and Option B protocols:5.11.1 Water retention in the solid material sample between weekly leaches is more variable for Option A than in Option B; for Option A, standard deviations from the mean water retention can range from 20 to 60 % of the mean value; comparable values for Option B have been reported at less than 9 % (14).5.11.2 Greater water retention in Option B cells may favor dissolution of, and consequent acid neutralization by, magnesium-bearing minerals; increased retention may facilitate transport of acidic reaction products from iron-sulfide minerals to magnesium-bearing minerals (14).5.11.3 Comparisons of sulfate mass release from the same sample subjected to Option A and Option B protocols indicate no significant difference in sulfate concentration as a result of water-retention variation between protocols (14). This suggests the increased water retention of Option B does not limit oxygen diffusion to the extent that sulfide mineral oxidation rates are reduced (14). However, samples containing greater than 7 % sulfur have not as yet been subjected to comparable Option A and Option B protocol studies.NOTE 3: Examples of products from the test include the following: (1) effluent pH, acidity/alkalinity, and specific conductance; (2) cumulative mass release of individual solutes; and (3) release rates for individual solutes (for example, the average release of μg sulfate/g of solid material sample/week). The dissolution time required for depletion of estimated NP and the subsequent duration of acid generation can be estimated using the values generated in items (2) and (3) above (15).1.1 This kinetic test method covers a laboratory weathering procedure that (1) enhances reaction-product transport in the aqueous leach of a solid material sample of specified mass, and (2) measures rates of weathering-product mass release. Soluble weathering products are mobilized by a fixed-volume aqueous leach that is performed and collected weekly. Leachate samples are analyzed for pH, alkalinity/acidity, specific conductance, sulfate, and other selected analytes.1.1.1 This test method is intended for use to meet kinetic testing regulatory requirements for mining waste rock and ores sized to pass a 6.3-mm (0.25-in.) Tyler screen.1.1.2 Interlaboratory testing of this method has been confined to mine waste rock. Application of this test method to metallurgical processing waste (for example, mill tailings) is outside the scope of the test method.1.2 This test method is a modification of a laboratory weathering procedure developed originally for mining wastes (1-3).2 However, it may have useful application wherever gaseous oxidation coupled with aqueous leaching are important mechanisms for contaminant mobility.1.3 This test method calls for the weekly leaching of a well-characterized solid material sample (weighing at least 1000 g) with water of specified purity, and the collection and chemical characterization of the resulting leachate. Test duration is determined by the user’s objectives of the test. See Guide D8187.31.4 As described, this test method may not be suitable for some materials containing plastics, polymers, or refined metals. These materials may be resistant to traditional particle size reduction methods.1.5 Additionally, this test method has not been tested for applicability to organic substances and volatile matter.1.6 This test method is not intended to provide leachates that are identical to the actual leachate produced from a solid material in the field or to produce leachates to be used as the sole basis of engineering design.1.7 This test method is not intended to simulate site-specific leaching conditions. It has not been demonstrated to simulate actual disposal site leaching conditions. Furthermore, the test is not designed to produce effluents that are in chemical equilibrium with the solid phase sample.1.8 This test method is intended to describe the procedure for performing the laboratory weathering of solid materials. It does not describe all types of sampling and analytical requirements that may be associated with its application.1.9 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.9.1 Exception—The values given in parentheses are for information only.1.10 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.11 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

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定价： 590元 加购物车

This specification covers preformed open-cell sponge rubber gaskets, for use in new or reconditioned pails or drums, of the following classes: Class A and Class B, each divided into Grade 1, Grade 2, and Grade 3. Cellular sponge rubber gaskets shall be made by incorporating a blowing agent into the compound, such as sodium bicarbonate, that gives off a gas which expands the mass during the vulcanization process, and shall be manufactured from natural rubber, synthetic rubber, or rubber-like materials, together with added compounding ingredients. Unless otherwise specified, gasket sponge rubber shall have a natural skin on both the top and bottom surfaces. Cellular rubber shall conform to the prescribed requirements as to physical properties such as (1) compression at deflection, (2) change in volume upon oil immersion, (3) change in compression value after heat aging, (4) compression set, and (5) color (tan or black). The following test methods shall be used: (1) compression deflection test, (2) oil immersion test, (3) heat oven aging test, and (4) compression set test under constant deflection. The formula for calculating the compression set is given. The requirements for sampling, test specimens and slabs, and measurements of test specimen such as width and thickness are detailed as well. The location from which standard test specimens are to be cut when testing standard test slabs or commercial flat sheets and the four-cavity frame for standard test slabs of cellular rubbers are illustrated.1.1 This specification covers preformed open–cell sponge rubber gaskets of the following classes for use in new or reconditioned pails or drums.1.1.1 Class A—Non–Oil Resistant.1.1.2 Class B—Oil Resistant.1.2 The values stated in SI units are to be regarded as the standard.1.3 The following safety hazards caveat pertains only to Section 10, General Test Methods. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.NOTE 1: ISO Equivalency Statement—This proposed specification was found to be not equivalent.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 加购物车

5.1 The number and distribution of viable and non-viable cells within, or on the surface of, a biomaterial scaffold is one of several important characteristics that may determine in vivo product performance of cell/biomaterial constructs (see 5.7); therefore, there is a need for standardized test methods to quantify cell viability.5.2 There are a variety of static and dynamic methods to seed cells on scaffolds, each with different cell seeding efficiencies. In general, static methods such as direct pipetting of cells onto scaffold surfaces have been shown to have lower cell seeding efficiencies than dynamic methods that push cells into the scaffold interior. Dynamic methods include: injection of cells into the scaffold, cell seeding on biomaterials contained in spinner flasks or perfusion chambers, or seeding that is enhanced by the application of centrifugal forces. The methods described in this guide can assist in establishing cell seeding efficiencies as a function of seeding method and for standardizing viable cell numbers within a given methodology.5.3 As described in Guide F2315, thick scaffolds or scaffolds highly loaded with cells lead to diffusion limitations during culture or implantation that can result in cell death in the center of the construct, leaving only an outer rim of viable cells. Spatial variations of viable cells such as this may be quantified using the tests within this guide. The effectiveness of the culturing method or bioreactor conditions on the viability of the cells throughout the scaffold can also be evaluated with the methods described in this guide.5.4 These test methods can be used to quantify cells on non-porous or within porous hard or soft 3-D synthetic or natural-based biomaterials, such as ceramics, polymers, hydrogels, and decellularized extracellular matrices. The test methods also apply to cells seeded on porous coatings.5.5 Test methods described in this guide may also be used to distinguish between proliferating and non-proliferating viable cells. Proliferating cells proceed through the DNA synthesis (S) phase and the mitosis (M) phase to produce two daughter cells. Non-proliferating viable cells are in some phase of the cell cycle, but are not necessarily proceeding through the cell cycle culminating in proliferation.5.6 Viable cells may be under stress or undergoing apoptosis. Assays for evaluating cell stress or apoptosis are not addressed in this guide.5.7 While cell viability is an important characteristic of a TEMP, the biological performance of a TEMP is dependent on additional parameters. Additional tests to evaluate and confirm the cell identity, protein expression, genetic profile, lineage progression, extent of differentiation, activation status, and morphology are recommended.5.8 The main focus of this document is not scaffold toxicity or the toxicity of the scaffold raw materials. This document is meant to address the situation where a scaffold that is thought to be cytocompatible is cultured with cells and the user desires to assess the viability of cells within the construct. Prior to conducting the tests described herein, the raw materials used to make the scaffold should be assessed as described in Practice F748. This testing may include assessment of the release of toxic leachables from the raw materials.5.9 Methods that remove the cells from a 3-D scaffold may reduce the cell number and viability due to the manipulation required.5.10 Some scaffold constructs may prevent reliable measurements of cell viability within the scaffolds using the methods described herein. Scaffolds may limit diffusion of assay components into and out of the scaffolds. This is especially problematic for methods that require dyes to penetrate into the scaffold, that require detergents or other cell-lysing agents to diffuse into the construct, that require lysed-cell components to diffuse out of the constructs, or that require assay reactants to diffuse into or out of the scaffold. Diffusion in scaffolds and assay results may also be affected by dense cell populations in scaffolds, the generation of tissue-like structures by the cells within the scaffold, and the presence of cell-generated extracellular matrix (ECM) in the scaffold. The formation of tight junctions between cells and cell-ECM interactions may also limit diffusion, especially in the case of hard tissues such as bone.5.11 Assay results may be affected by interactions between assay components and the scaffold. Assay components may adsorb to the surface of the scaffold which would affect their participation in the assay and the resulting assay signal. Biochemical interactions between the scaffold and assay components may cause activation or inhibition of the assay chemistries.5.12 Different cell viability tests may measure different things and may not agree with one another. A large variety of cell viability assays have been developed to measure different aspects of the cell death process. Some of the common measurements include penetration of dyes into the cell, cell metabolic activity, cellular ATP, and leakage of intracellular components out of the cell. Each of these phenomena are related to the state of cell viability in different ways, and may represent different attributes of the cell death process. The mechanism of cell death will also affect the results for these different types of viability measurements. Necrosis, oxygen depravation, starvation, chemical toxicity, apoptosis, anoikis, and mechanical damage represent some of the causes of cell death. Each of these mechanisms may have different effects on the different aspects of cell death that are measured by cell viability assays.1.1 This guide is a resource of cell viability test methods that can be used to assess the number and distribution of viable and non-viable cells within porous and non-porous, hard or soft biomaterial scaffolds, such as those used in tissue-engineered medical products (TEMPs).1.2 In addition to providing a compendium of available techniques, this guide describes materials-specific interactions with the cell assays that can interfere with accurate cell viability analysis, and includes guidance on how to avoid or account for, or both, scaffold material/cell viability assay interactions.1.3 These methods can be used for 3-D scaffolds containing cells that have been cultured in vitro or for scaffold/cell constructs that are retrieved after implantation in living organisms.1.4 This guide does not propose acceptance criteria based on the application of cell viability test methods.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 加购物车

定价： 646元 加购物车

定价： 646元 加购物车

定价： 646元 加购物车

5.1  Hydrogen is delivered to fuel cell powered automotive vehicles and stationary appliances at pressures up to 87.5 MPa. The quality of hydrogen delivered is a significant factor in maximizing fuel cell efficiency and life span. Contamination can occur during the production of fuel cell feed gases, contaminating storage containers, station tubing, and fuel lines used for fuel delivery. Collection of a representative fuel sample without the introduction of contaminants even as low as parts-per-billion (ppb) per contaminant during collection is crucial for assessing the quality of fuel in real world applications.5.2 This practice is intended for application to high pressure, high purity hydrogen; however, the apparatus design and sampling techniques may be applicable to collection of other fuel cell feed gases. Many of the techniques used in this practice can be applied to lower pressure/lower purity gas streams.1.1 This standard practice describes a sampling procedure of high pressure hydrogen at fueling stations operating at 35 or 70 megapascals (MPa) using a hydrogen quality sampling apparatus (HQSA).1.2 This practice does not include the analysis of the acquired sample. Applicable ASTM standards include but are not limited to test methods referenced in Section 2 of this practice.1.3 This practice is not intended for sampling and measuring particulate matter in high pressure hydrogen. For procedures on sampling and measuring particulate matter see ASTM D7650 and D7651.1.4 The values stated in SI units are standard. The values stated in inch-pounds are for information only.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

定价： 590元 加购物车