Post-gamma irradiation cross-linking of polyethylene tape by acetylene treatment

1994 ◽  
Vol 29 (1) ◽  
pp. 227-231 ◽  
Author(s):  
R. W. Appleby ◽  
W. K. Busfield
Keyword(s):  
Gamma Irradiation ◽  
Cross Linking

Novel way to control PDMS cross-linking by gamma-irradiation

2008 ◽  
Vol 266 (7) ◽  
pp. 1105-1108 ◽  
Author(s):  
S.R. Gomes ◽  
F.M.A. Margaça ◽  
D. Faria Silva ◽  
L.M. Ferreira ◽  
I.M. Miranda Salvado ◽  
...  
Keyword(s):  
Gamma Irradiation ◽  
Cross Linking

scholarly journals Disposable N95 Masks Pass Qualitative Fit-Test But Have Decreased Filtration Efficiency after Cobalt-60 Gamma Irradiation

2020 ◽  
Author(s):  
Avilash Cramer ◽  
Enze Tian ◽  
Sherry H. Yu ◽  
Mitchell Galanek ◽  
Edward Lamere ◽  
...  
Keyword(s):  
Gamma Radiation ◽  
Gamma Irradiation ◽  
Personal Protective Equipment ◽  
Fiber Material ◽  
Filtration Efficiency ◽  
Cross Linking ◽  
Protective Equipment ◽  
Viral Inactivation ◽  
Sterilization Method ◽  
Blinded Study

ABSTRACTThe current COVID-19 pandemic has led to a dramatic shortage of masks and other personal protective equipment (PPE) in hospitals around the globe [1]. One component of PPE that is in particular demand are disposable N95 face masks. To alleviate this, many methods of N95 mask sterilization have been studied and proposed with the hope of being able to safely reuse masks [2]. Two major considerations must be made when re-sterilizing masks: (1) the sterilization method effectively kills pathogens, penetrating into the fibers of the mask, and (2) the method does not degrade the operational integrity of the N95 filters.We studied Cobalt-60 (60Co) gamma irradiation as a method of effective sterilization without inducing mask degradation. Significant literature exists supporting the use of gamma radiation as a sterilization method, with viral inactivation of SARS-CoV reported at doses of at most 10 kGy [3], with other studies supporting 5 kGy for many types of viruses [4]. However, concerns have been raised about the radiation damaging the fiber material within the mask, specifically by causing cross-linking of polymers, leading to cracking and degradation during fitting and/or deployment [5, 6].A set of 3M 8210 and 9105 masks were irradiated using MIT’s 60Co irradiator. Three masks of each type received 0 kiloGray (kGy), 10 kGy and 50 kGy of approximately 1.3 MeV gamma radiation from the circular cobalt sources, at a dose rate of 2.2kGy per hour.Following this sterilization procedure, the irradiated masks passed a OSHA Gerson Qualitative Fit Test QLFT 50 (saccharin apparatus) [7] when donned correctly, performed at the Brigham and Women’s Hospital, in a blinded study repeated in triplicate. However, the masks’ filtration of 0.3 µm particles was significantly degraded, even at 10 kGy.These results suggest against gamma, and possibly all ionizing radiation, as a method of disposable N95 sterilization. Even more importantly, they argue against using the qualitative fit test alone to assess mask integrity.

Irradiation-Induced Changes in Hydroxypropyl Cellulose

1995 ◽  
Vol 394 ◽  
Author(s):  
Mark A. Petrich ◽  
Lawrence A. Rosen
Keyword(s):  
Molecular Weight ◽  
Gamma Irradiation ◽  
Pharmaceutical Formulations ◽  
Hydroxypropyl Cellulose ◽  
Water Soluble ◽  
Cross Linking ◽  
Dissolution Behavior ◽  
Subsequent Effect ◽  
Sterilization Process ◽  
Induced Changes

AbstractGamma irradiation is used to sterilize products intended for ophthalmic and parenteral use. Ideally, the sterilization process should not affect the chemical identity or physical properties of the product. We have investigated the effects of gamma irradiation on the structure and molecular weight of hydroxypropyl cellulose (HPC), and the subsequent effect on dissolution behavior of HPC. Hydroxypropyl cellulose is a commonly used excipient in pharmaceutical formulations and tablet coatings, and can be used to manufacture water soluble objects. We find that the moisture content of the HPC influences the extent to which scission and cross-linking reactions occur. At low moisture levels (<5 wt.%), cross-linking is relatively unimportant, while above 12 wt. % moisture cross-linking becomes extensive leading to formation of insoluble, rubber-like gels.

Electrodes with polymer network films formed by .gamma.-irradiation cross-linking

1987 ◽  
Vol 59 (1) ◽  
pp. 134-139 ◽  
Author(s):  
Emory S. De Castro ◽  
Edward W. Huber ◽  
Denis. Villarroel ◽  
Christos. Galiatsatos ◽  
James E. Mark ◽  
...  
Keyword(s):  
Gamma Irradiation ◽  
Polymer Network ◽  
Cross Linking

scholarly journals Free-radical-mediated fragmentation of monoamine oxidase in the mitochondrial membrane Roles for lipid radicals

1986 ◽  
Vol 240 (2) ◽  
pp. 489-494 ◽  
Author(s):  
R T Dean ◽  
S M Thomas ◽  
A Garner
Keyword(s):  
Lipid Peroxidation ◽  
Monoamine Oxidase ◽  
Gamma Irradiation ◽  
Hydroxyl Radicals ◽  
Protein Turnover ◽  
Mitochondrial Membrane ◽  
Cross Linking ◽  
Submitochondrial Particles ◽  
Protein Activity ◽  
Lipid Radicals

A flux of hydroxyl radicals generated by gamma-irradiation can fragment monoamine oxidase in the membrane of submitochondrial particles. This fragmentation can be inhibited by mannitol and in addition is more extensive in monoamine oxidase preparations that have been depleted of lipid. This latter observation is consistent with the higher yields of fragmentation induced by hydroxyl radicals in soluble proteins in the absence of added lipids. In the absence of oxygen, gamma-irradiation of submitochondrial particles leads to cross-linking reactions. A flux of hydroperoxyl radicals also causes fragmentation, whereas one of superoxide is virtually inactive in this respect. The irradiation of submitochondrial particles leads in addition to the accumulation of products of lipid peroxidation. When these irradiated preparations are exposed to ferrous or cupric salts a further fragmentation of monoamine oxidase ensues, especially at acid pH. These transition-metal-catalysed reactions do not occur with irradiated preparations depleted of lipid, and the post-irradiation protein modifications are concomitant with further lipid peroxidation. The data indicate roles for lipid radicals in both fragmentation and cross-linking reactions of proteins in biological membranes. These reactions may have an important bearing on control of protein activity and of protein turnover in membranes.

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