Glass Contamination Research Articles

Glass contamination in IM injections is common

Glass contamination in IM injections is common

Detection of glass contamination in horticultural peat with dual-energy X-ray absorptiometry (DXA)

The application of dual-energy X-ray absorptiometry (DXA) to the detection of glass contamination in horticultural peat was studied using contaminated peat specimens, imaged with X-ray energies of 40 and 70 kVp and without any physical disruption of the peat samples. The source was an uncollimated beam from an industrial X-ray non-destructive testing system. X-ray transmission characteristics of peat and glass were determined from chemical composition data using XCOM software. The DXA images were analysed for detectivity figure (DF), signal-to-noise ratio (SNR) and contrast. These quantities were compared with those of the unprocessed 40 kVp images. There was >75% detection of glass presence if thicker than 3 mm, but 100% detection of glass fragments thicker than 1 mm. It was not possible to distinguish between glass and stone. DF values were dependent on peat and glass type, and contrast more than doubled with the DXA-derived images compared with their 40 kVp counterparts. Comparison with reported figures for a luggage inspection system shows that this system performs better than expected for commercial security systems. Better DXA results may be possible using simultaneous energy detection, and such a multi-energy sensing system could allow glass/stone detection as part of peat quality assurance, and the determination of peat chemical composition.

Ceramic crucibles: a new alternative for melting of PbO–BiO 1.5–GaO 1.5 glasses

PbO–Bi 2O 3–Ga 2O 3 glasses present interesting properties such as good transmission in the mid-infrared region, high magnetic Verdet constant and non-linear properties. The processing of these heavy-metal-oxide (HMO) glasses is limited by the high corrosive nature of the melt, even in relation to noble metal crucibles. In this work, three kinds of ceramic crucibles (alumina, tin oxide and zirconia) were tested for melting HMO glasses. The main physical properties of the prepared glasses, such as the characteristic temperatures, optical transmission were studied in function of the crucible nature, time/temperature melting parameters. The incorporation of crucible material in the glasses was determined by ICP and atomic absorption. The maximum glass contamination from the crucible was 2.9, 1.6 and 3.6 mol% for Al 2O 3, SnO 2 and ZrO 2 crucibles, respectively, when melting was done at 900 °C/240 min, for zirconia crucibles and at 1000 °C/60 min, for the other two crucibles. The evolution of the physical properties was discussed as a function of contamination degree.

Ethics of Justice and Care in Corporate Crisis Management

Despite the importance of ethics in corporate crisis management, they have received limited attention in the academic literature. This article contributes to the evolving conversation on ethics in crisis management by elucidating the ethics of "justice" and "care" and distinguishing between them. Examples of the two approaches are offered through consideration of cases in corporate crisis management, including the alleged glass contamination case faced by Gerber Products Company, and, the shooting tragedy at San Ysidro faced by McDonald's Corporation. It is argued that both an ethic of justice and an ethic of care can be appropriate approaches in corporate crisis management. Areas for future research are discussed.

Determination of zircon/melt trace element partition coefficients from SIMS analysis of melt inclusions in zircon

Partition coefficients ( zircon/meltD M) for rare earth elements (REE) (La, Ce, Nd, Sm, Dy, Er and Yb) and other trace elements (Ba, Rb, B, Sr, Ti, Y and Nb) between zircon and melt have been calculated from secondary ion mass spectrometric (SIMS) analyses of zircon/melt inclusion pairs. The melt inclusion-mineral (MIM) technique shows that D REE increase in compatibility with increasing atomic number, similar to results of previous studies. However, D REE determined using the MIM technique are, in general, lower than previously reported values. Calculated D REE indicate that light REE with atomic numbers less than Sm are incompatible in zircon and become more incompatible with decreasing atomic number. This behavior is in contrast to most previously published results which indicate D > 1 and define a flat partitioning pattern for elements from La through Sm. The partition coefficients for the heavy REE determined using the MIM technique are lower than previously published results by factors of ≈15 to 20 but follow a similar trend. These differences are thought to reflect the effects of mineral and/or glass contaminants in samples from earlier studies which employed bulk analysis techniques. D REE determined using the MIM technique agree well with values predicted using the equations of Brice (1975), which are based on the size and elasticity of crystallographic sites. The presence of Ce 4+ in the melt results in elevated D Ce compared to neighboring REE due to the similar valence and size of Ce 4+ and Zr 4+. Predicted zircon/meltD values for Ce 4+ and Ce 3+ indicate that the Ce 4+/Ce 3+ ratios of the melt ranged from about 10 −3 to 10 −2. Partition coefficients for other trace elements determined in this study increase in compatibility in the order Ba < Rb < B < Sr < Ti < Y < Nb, with Ba, Rb, B and Sr showing incompatible behavior (D M < 1.0), and Ti, Y and Nb showing compatible behavior (D M > 1.0). The effect of partition coefficients on melt evolution during petrogenetic modeling was examined using partition coefficients determined in this study and compared to trends obtained using published partition coefficients. The lower D REE determined in this study result in smaller REE bulk distribution coefficients, for a given mineral assemblage, compared to those calculated using previously reported values. As an example, fractional crystallization of an assemblage composed of 35% hornblende, 64.5% plagioclase and 0.5% zircon produces a melt that becomes increasingly more enriched in Yb using the D Yb from this study. Using D Yb from Fujimaki (1986) results in a melt that becomes progressively depleted in Yb during crystallization.

Ar and K partitioning between clinopyroxene and silicate melt to 8 GPa

The relative incompatibility of Ar and K are fundamental parameters in understanding the degassing history of the mantle. Clinopyroxene is the main host for K in most of the upper mantle, playing an important role in controlling the K/Ar ratio of residual mantle and the subsequent time-integrated evolution of 40Ar/36Ar ratios. Clinopyroxene also contributes to the bulk Ar partition coefficient that controls the Ar degassing rate during mantle melting. The partitioning of Ar and K between clinopyroxene and quenched silicate melt has been experimentally determined from 1 to 8 GPa for the bulk compositions Ab80Di20 (80 mol% albite-20 mol% diopside) and Ab20Di80 with an ultraviolet laser ablation microprobe (UVLAMP) technique for Ar analysis and the ion microprobe for K. Data for Kr (UVLAMP) and Rb (ion probe) have also been determined to evaluate the role of crystal lattice sites in controlling partitioning. By excluding crystal analyses that show evidence of glass contamination, we find relatively constant Ar partition coefficients (DAr) of 2.6 × 10−4 to 3.9 × 10−4 for the Ab80Di20 system at pressures from 2 to 8 GPa. In the Ab20Di80 system, DAr shows similar low values of 7.0 × 10−5 and 3.0 × 10−4 at 1 to 3 GPa. All these values are several orders of magnitude lower than previous measurements on separated crystal-glass pairs.DK is 10 to 50 times greater than DRb for all experiments, and both elements follow parallel trends with increasing pressure, although these trends are significantly different in each system studied. The DK values for clinopyroxene are at least an order of magnitude greater than DAr under all conditions investigated here, but DAr appears to show more consistent behavior between the two systems than K or Rb. The partitioning behavior of K and Rb can be explained in terms of combined pressure, temperature, and crystal chemistry effects that result in changes for the size of the clinopyroxene M2 site. In the Ab20Di80 system, where clinopyroxene is diopside rich at all pressures, DK and DRb increase with pressure (and temperature) in an analogous fashion to the well-documented behavior of Na. For the Ab80Di20 system, the jadeite content of the clinopyroxene increases from 22 to 75 mol% with pressure resulting in a contraction of the M2 site. This has the effect of discriminating against the large K+ and Rb+ ions, thereby countering the effect of increasing pressure. As a consequence DK and DRb do not increase with pressure in this system.In contrast to the alkalis (Na, K, and Rb), DKr values are similar to DAr despite a large difference in atomic radius. This lack of discrimination (and the constant DAr over a range of crystal compositions) is also consistent with incorporation of these heavier noble gases at crystal lattice sites and a predicted consequence of their neutrality or “zero charge.” Combined with published DAr values for olivine, our results confirm that magma generation is an efficient mechanism for the removal of Ar from the uppermost 200 km of the mantle, and that K/Ar ratios in the residuum are controlled by the amount of clinopyroxene. Generally, Ar is more compatible than K during mantle melting because DAr for olivine is similar to DK for clinopyroxene. As a result, residual mantle that has experienced variable amounts of melt extraction may show considerable variability in time-integrated 36Ar/40Ar.

Analytical Techniques for Glass Contamination of Food: A Guide for Administrators and Analysts

An analytical scheme is presented to provide an overview of techniques applicable to glass contamination in a variety of consumer products. Procedures are referenced or presented in detail, with emphasis on quality assurance. References on forensic and analytical methods for the examination of glass are provided.

Glass ampules and associated hazards

Accessing drugs dispensed in glass ampules is always associated with glass fragment contamination of the ampule contents on opening. In this study, the glass fragment contamination from the external surface of the ampule occurred 60% of the time with 1-ml sized ampules (p less than .01). Glass contamination has been shown to increase with larger ampule size. The glass ampule poses a potential source of microbial infection to the patient, as well as other hazards to the user. Increased precautions and improved drug container design appear to be desirable.

Control of Glass in Waste‐to‐Energy Production

Mechanisms that contribute to glass contamination of waste‐to‐energy products from air classifiers are studied, and modifications to unit processes are suggested. Vertical air classifiers are used to extract the combustible organic fraction from municipal solid waste (MSW); however, unit operations preceding these classifiers tend to produce glass particles which, despite a relatively high density, tend to move with the organics once they reach the classifier. Experience in burning waste‐to‐energy fuel indicates critical problems are associated with the presence of these inorganic fines in the fuel, including excessive slagging on incinerator walls and abrasion of mechanical parts. This research investigates the relationships between glass particle size and air velocity within the classifier, and details the effects paper particles and moisture have on glass particle transport. Laboratory results lead to conclusions which suggest changes in the operation of air classifiers, and imply designs for selected unit operations which precede the classifiers.

Pulsed‐Flow Air Classification for Waste‐to‐Energy

The development and testing of the concept of pulsed‐flow air classification for waste‐to‐energy production are discussed. Air classifiers, a potentially valuable unit operation in waste‐to‐energy production facilities, currently do not meet expectations. Standard designs generally lose large amounts of combustible material as well as produce a fuel that is high in metal and glass contaminants. Pulsed‐flow classification is presented as a concept which can avoid both pitfalls. Municipal solid waste (MSW) is composed of particles which can be cataloged as combustible and non‐combustible fractions by defining a density split between aluminum and plastic: generally all other non‐combustibles are more dense than aluminum, while all other combustibles are less dense than plastic. However, current designs for classifiers tend to separate by aerodynamic characteristics which do not always produce a split based on density alone. Pulsed‐flow classifiers are seen to offer a unique solution to this puzzle. In this paper, each aspect of theory and laboratory testing is presented, including: (1) Preliminary determination; (2) particle characteristics; (3) theory of pulsed‐flow classification; (4) experimental equipment; (5) laboratory testing; and (6) pulsed‐flow air classification for energy production. Conclusions from the research are summarized in the final section of the paper.

Avoiding glass contamination in removing samples from evacuated tubes

Avoiding glass contamination in removing samples from evacuated tubes

Effects of Glass Contamination and Electrode Curvature on Electrical Breakdown in Vacuum

It has recently been found that particles of contamination reside on surfaces inside vacuum systems as a result of thermal decomposition of glass. These particles contain at least Na, K, and B as well as traces of Al and Si. They may well have been important in many clean surface experiments. Our investigation has shown that these particles have a strong influence in reducing the breakdown voltage in vacuum. Breakdown voltages for Al, Cu, and stainless steel electrodes with radii of curvature of 12.7, 25.4, 50.8, and 101.6 mm were determined under clean and contaminated conditions at 10−5 Torr. It was found that under clean conditions the electrodes of smaller radii of curvature have higher breakdown voltages than the more nearly plane electrodes.