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The Poisoned Chalice
Published in Alan Perkins, Life and Death Rays, 2021
Thallium is a heavy chemical element with the symbol ‘Tl’ and atomic number 81. There are 25 isotopes of thallium with atomic masses ranging from 184 to 210. The only stable isotopes of the metal are thallium-210 and thallium-205, the rest being radioactive. It is a soft, malleable, grey metal that is not found freely in nature. The name thallium comes from the Greek word thallos, which means green shoot or twig. This name was given to the metal as a result of the green flame it produced when heated in a flame test, as in William Crookes’ initial observations. When separated in a pure form, thallium resembles tin, but it becomes discoloured when exposed to air.
Industrial Uses Of Phosphonates
Published in Richard L. Hilderbrand, The Role of Phosphonates in Living Systems, 2018
George L. Drake, Timothy A. Calamari
These monomers may be polymerized with a benzoyl peroxide catalyst at about 85 to 100°C. Better flame retardants are prepared; however, when the monomers are first partially brominated and then polymerized. About 25% add-on of the partially brominated polymer product is required for an 8 oz cotton fabric to provide sufficient flame resistance to pass the standard vertical flame test. The relatively high add-ons are probably accounted for by the high percentage of fuel (carbon and hydrogen) that is added per unit of phosphorus and bromine. In general, these polymers are about equivalent in flame retardancy to the bromoform adduct of triallyl phosphate. The phosphonate polymers are somewhat more impervious to alkaline laundering than polymers made from phosphates. The phosphonates are applied to fabric from an organic solvent or a mixture of solvents, (such as methanol and ethylene dichloride), using a pad-dry-cure procedure. Curing at an elevated temperature is not required. The flame-retardant finishes withstand several accelerated laundering cycles.
Interaction effects of washing and abrasion on thermal protective performance of flame-retardant fabrics
Published in International Journal of Occupational Safety and Ergonomics, 2021
Lijun Wang, Jiazhen He, Yehu Lu, Shumin Jiang, Min Wang
In this study, the effects of washing, abrasion and their interaction effects on thermal protection provided by flame-retardant fabrics under exposure to flame and radiant heat were investigated. It was found that the thickness of the fabric increased with the washing or abrasion cycles, while the mass firstly increased and then decreased. Thermal protection indicated by TPP and RPP values firstly increased after washing or abrasion, and then decreased with further increasing cycles of washing or abrasion. As a result of a combined action of washing and abrasion, the TPP and RPP values of the fabric showed a lower trend compared with those of the ones treated by washing or abrasion only, which indicated that the combination action was greater than the action of washing or abrasion alone. Moreover, with the same cycles of washing and abrasion the interaction modes showed significant differences in thermal protection in a flame test. The impact of heat exposure should also be considered to analyze the combined effect of washing and abrasion on thermal protection. In addition, a positive correlation was observed between the fabric mass and the TPP and RPP values of the fabrics after treatment under both exposures to flame and radiant heat.
Identification of mothball powder composition by float tests and melting point tests
Published in Clinical Toxicology, 2018
Mothballs are composed of either camphor, naphthalene or paradichlorobenzene. Mothballs sold in developed nations typically contain naphthalene and paradichlorobenzene. Accidental ingestion of mothballs of unknown composition is common in children. Naphthalene ingestion may cause haemolytic anaemia and methemoglobinemia, while camphor ingestion may cause central nervous system depression and seizure. Paradichlorobenzene ingestion is relatively benign. Recently, we reported a psychiatric patient who had ground up naphthalene mothballs and ingested 60 g of the powder. He developed haemolytic anaemia and presented with dark urine [1]. A woman without glucose-6-phosphate dehydrogenase deficiency who accidentally ingested two powdered naphthalene mothballs mixed in 5 ml of coconut oil developed severe haemolytic anaemia [2]. Naphthalene powder can be purchased on the internet for use as a surfactant, as a fumigant, and to create special pyrotechnic effects such as the generation of ‘black smoke’ [3]. Camphor powder can be obtained online for use in medicine and religious purposes in some countries [4]. Occasionally after the accidental chewing of mothballs by children, only tiny fragmented remnants were left for examination. To identify the compositions of intact mothballs, various tests, including the melting point test, the float test using a saturated salt solution, the float test using a 50% dextrose solution (D50), the color change test with the addition of chloroform, the flame test, and the turpentine solubility test, have been described [5–10]. Small amounts (0.1–0.3 g) of unknown mothballs could be differentiated into paradichlorobenzene or naphthalene by melting point tests [5]. Mothballs fragmented by a hammer were differentiated by float tests in a recent study [11]. However, to date, no study has identified the composition of unknown mothballs in powdered form, i.e., naphthalene powder, paradichlorobenzene powder and camphor powder. Of the various tests listed above, the melting point test and the float test are practical, and the required materials are readily available in homes and emergency departments. Float tests have the advantage of being able to identify all three compositions of intact mothballs while melting point tests can only differentiate between naphthalene and paradichlorobenzene mothballs. Therefore, we studied whether melting point tests and float tests could successfully differentiate paradichlorobenzene powder from non-paradichlorobenzene powder (naphthalene powder and camphor powder), and compared the pros and cons of these methods.