Controlling the Size of BaF2 Nanocubes from 1000 to 10 nm

✦ Synopsis

Abstract

Size control of BaF~2~ nanocubes has been achieved by varying reaction time and pH value, thus producing nanocubes with a controllable edge length in the range 10–1000 nm. A linear relationship between cube size and reaction time has been revealed. Furthermore, a process has been developed to separate the growing BaF~2~ nanocubes from the remaining solid products at different stages of the synthesis. On the basis of the observed crystallite morphologies, we have elucidated an “extension growing” mechanism to describe the size‐controlled growth of BaF~2~ nanocubes using this method. Photoluminescence results demonstrate that the deoxidant selenite ions prevent the incorporation of oxygen into the BaF~2~ nanocubes effectually, which will greatly affect their performance as scintillators. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Acute and Chronic Toxicity of Veratrum V

Acute and Chronic Toxicity of Veratrum Viride††The Veratrum viride studied was the whole-powdered drug marketed by Irwin, Neisler & Co. under the name, Vertavis. The work reported herein was supported by a grant from this firm. The batch of powder used in these experiments was stated by the manufacturer to have been assayed biologically by the Craw method on Daphnia magna. One Craw unit of the material studied was stated to be 15.6mg. With regard to this assay, Mr. R. O. Craw has been so kind as to allow us to publish a brief explanation: A reference lot of Yerolrum oirid; powder was set-aside as a standard and a 10% w/v aqueous extract was made of this powder. The average median length of life in 50 assays of 1000 daphnia on immersion in the solution was determined to be 2.22 hours. The daphnia were considered dead when the heart was found to be in systolic standstill on microscopic examination. Succeeding lots of powder were assayed and their potency determined by relating the median length of life of daphnia to 2.22 hours, which is one unit. Twenty assays of 10 animals each were used on each lot of powder.‡‡The authors wish to thank Dr. J. F. A.,McManus of the Department of Pathology for a pathologic report on the tissues, and Mr. James Thomas and Mrs. Bobby E. Teague for technical assistance.

✍ Perdue, Adoline S. ;Bell, Frances ;Starnes, W.R. ;Hitchcock, Philip ;Teague, R.S 📂 Article 📅 1950 🏛 Elsevier ⚖ 346 KB