Bibliothek

Notizen: Studies have been done on the absorption and metabolism of the hair colourant 2-nitro-p-phenylenediamine (2-NPPD) in rats with particular reference to skin penetration.When [14C]2-NPPD was given orally or injected intraperitoneally into male and female rats, excretion was rapid and mainly in the faeces (60%) and urine (35%). No radioactivity was measurable in the expired air. At 3 days after dosing, approximately 2% of the dose was retained in the body.Application of [14C]2-NPPD in ethanol to the clipped skin of rats gave a high skin penetration. Male rats absorbed less (11.7 μg cm-2) through the skin than did female rats (24.6 μg cm-2).Application of [14C]2-NPPD in a solution of a hair colourant product base to the clipped skin of rats gave a high penetration if the skin was occluded or not rinsed. Penetration was much reduced after rinsing and protection by non-occlusive patches. With these latter conditions, skin penetration in clipped rats treated with a 0.5% (w/v) solution of [14C]2-NPPD doubled to 6.1 μg cm-2 when the contact time was increased from 5 to 30 minutes, increased two to three times after two and three repeated applications, increased in proportion to the applied concentration and was reduced by half when applied to unclipped skin.The metabolic pattern in urine from rats after different routes of administration showed only a trace of the parent [14C]2-NPPD but six other radioactive components. The identity of these components has not yet been fully resolved. Blood levels of radio-activity during 2 days after topical administration were low.Under realistic conditions of use by the consumer the calculated dose through the skin based on the experimental rat data is up to 10 μg/kg body weight per application of a semi-permanent hair colourant product containing 1% of 2-NPPD. L'adsorption transcutanée de la 2-nitro-p-phenylenediamine On a étudié l'adsorption transcutanée et le métabolisme du colorant capillaire 2-nitro-p-phenylènediamine (2-NPPD) sur le rat.Lorsque la [14C]2-NPPD est administrée par voie orale ou injectée par voie intra-péritonéale sur des rats mâles et femelles, l'excrétion est rapide et principalement dans les fèces (60%) et dans les urines (35%). Il n'y a pas de radioactivité mesurable dans l'air expiré. Trois jours après l'administration, environ 2% de la dose est retenue dans l'organisme.

Notizen: We present a systematic study of the infrared multiphoton excitation and dissociation of several polyatomic molecules. The molecules range in size from SO2, with three vibrational modes, to C3F7I, with 27. A gradual transition occurs from intensity dependent excitation, characteristic of a sparse density of vibrational states in small molecules, to a fluence dominated absorption characteristic of a quasicontinuum of vibrational states in large, heavy molecules. Molecules with ten or more atoms showed no intensity dependence under pulsed CO2 laser excitation at a fixed energy fluence. For a molecule to have a high probability of dissociation under realizable conditions of laser intensity and fluence, quasicontinuum region excitation must dominate. All molecules appeared to have statistically coupled vibrational modes at high levels of vibrational energy.

Notizen: Phase transformations of a thin film of Ba2YCu3Ox were induced with a focused laser beam in chemical ambients. The transformations, involving superconductive and nonsuperconductive phases, are achieved rapidly and with a high degree of spatial control. They are fully reversible, and the appropriate processing parameters have been studied. These effects are interpreted within present models, which relate the superconducting properties of Ba2YCu3Ox to its oxygen content and crystalline structure.

Notizen: A reaction, based on tungsten hexafluoride chemically reduced by silicon hydride vapors, has been developed for low-temperature laser deposition of high-purity tungsten. Compared to previous tungsten deposition methods, the new (pyrolytic) process requires very little thermal energy for initiation and propagation of the scanned reaction. WF6 and SiH4 (or Si2H6) mixtures have been optimized to yield tungsten interconnect lines with abrupt square cross section and conductivities of 12–25 μΩ cm. Impurity levels are below the detection limits of Auger spectroscopy. Lines 3–20 μm in width and 0.1–4 μm in thickness are written at scan speeds of ∼100 μm/s. Argon-ion laser powers (488 nm) are typically 30–60 mW, corresponding to reaction temperatures sufficiently low for direct writing on polyimide dielectrics.

Notizen: SUMMARY.— An autoradiographic technique for studying skin deposition and localization is described and applied to a study of germicides in surfactants. The method involves the use of unfixed frozen sections exposed to dry emulsion-coated slides.The radioactive germicides carboxy-14C-3,4,4′-trichlorocarbanilide (TCC) in soap containing non-soap detergent (NSD) and zinc or zirconium pyridine-2-thione-1-N-oxide (PTO) in a shampoo were applied to the skin of guinea-pigs. Auto-radiograms of the skins showed that from soap, TGC was deposited on the stratum corneum, around the entrances to hair follicles, and was seen in the epidermis and dermis, but not in the follicles or sebaceous glands. From the NSD, TCC was seen in addition in the follicles and sebaceous glands. In one human subject, TCC from NSD was seen on the corneum, in the epidermis and dermis, hair follicles and sebaceous glands and also in the sweat glands. From the shampoo ZnPTO and ZrPTO were seen in guinea-pig skin on the corneum and in the follicles but whereas ZrPTO was in the epidermis and dermis, ZnPTO was not. In all vehicles the largest proportion of germicide was deposited on the corneum.ZnPTO was shown to be soluble in sebum and to penetrate from sebum into only the hair follicles of guinea-pigs.Scintillation counting of sections of guinea-pig skin treated with TCC, ZnPTO and ZrPTO supported the autoradiographic evidence that most of the germicide remained on the corneum.