Band spectra produced by certain explosion mixtures

The method of exciting band spectra by explosion mixtures has wide applicability and should lead to the study of many new systems;The spectrum of MgS has been excited by this method and a band system obtained which degrades to the red;The heat of dissociation of the MgS molecule in two different states of excitation has been calculated;The spectrum of PbS molecules is easily photographed by the explosion method. The spectrum of PbS which resembles that of PbO is not easily analyzed;The advantages outweigh the disadvantages of the method for production of many spectra in the longer wavelength regions

A countercurrent liquid-liquid extractor

A novel countercurrent liquid-liquid extractor is presented and illustrated with applications. The apparatus consists essentially of an assembly of mixer-settlers, feeders, reservoirs, and flow lines that are made of glass or other chemical resistant materials. In operation this multistage assembly rotates intermittently in one direction on a horizontal axis causing the immiscible phases to progress to opposite ends of the unit. Details for the construction of the extractor and its principles of operation are given. Extractors of this design are applicable to experimental work and to the preparation of pure compounds in quantity

Sublimation of zirconium tetrafluoride

The demand for a dense zirconium tetrafluoride of high purity for use in the preparation of zirconium metal can be met by vacuum sublimation of zirconium fluoride prepared by the precipitation and dehydration method. Separation of zirconium fluoride from less volatile metallic impurities, moisture, and non-volatile zirconium compounds was accomplished in this manner. The degree of separation of the desired product improved with the use of lower sublimation temperatures; the lowest temperature was 750 degrees centigrade. Some fractionation from hafnium also occurred at this temperature, but zirconium tetrafluoride was the more volatile so a complete separation of zirconium from hafnium by sublimation does not seem practical

Oxidation studies of some refractory metals

Samples of niobium, tantalum, molybdenum and tungsten metals have been given phosphided cases by heating in a phosphorous atmosphere. The samples were subsequently exposed to air at an elevated temperature. In tests at 800°C, the phosphided samples resisted air oxidation markedly compared to the pure untreated samples. The phosphided cases were only a few microns thick yet oxidation resistance of all these samples extended for several hours. Phosphided samples with 90° edges did not resist oxidation at the edges as well as rounded edge samples

Copy Number Variation in Patients with Disorders of Sex Development Due to 46,XY Gonadal Dysgenesis

Disorders of sex development (DSD), ranging in severity from mild genital abnormalities to complete sex reversal, represent a major concern for patients and their families. DSD are often due to disruption of the genetic programs that regulate gonad development. Although some genes have been identified in these developmental pathways, the causative mutations have not been identified in more than 50% 46,XY DSD cases. We used the Affymetrix Genome-Wide Human SNP Array 6.0 to analyse copy number variation in 23 individuals with unexplained 46,XY DSD due to gonadal dysgenesis (GD). Here we describe three discrete changes in copy number that are the likely cause of the GD. Firstly, we identified a large duplication on the X chromosome that included DAX1 (NR0B1). Secondly, we identified a rearrangement that appears to affect a novel gonad-specific regulatory region in a known testis gene, SOX9. Surprisingly this patient lacked any signs of campomelic dysplasia, suggesting that the deletion affected expression of SOX9 only in the gonad. Functional analysis of potential SRY binding sites within this deleted region identified five putative enhancers, suggesting that sequences additional to the known SRY-binding TES enhancer influence human testis-specific SOX9 expression. Thirdly, we identified a small deletion immediately downstream of GATA4, supporting a role for GATA4 in gonad development in humans. These CNV analyses give new insights into the pathways involved in human gonad development and dysfunction, and suggest that rearrangements of non-coding sequences disturbing gene regulation may account for significant proportion of DSD cases

Synergistic Effect of SRY and Its Direct Target, WDR5, on Sox9 Expression

SRY is a sex-determining gene that encodes a transcription factor, which triggers male development in most mammals. The molecular mechanism of SRY action in testis determination is, however, poorly understood. In this study, we demonstrate that WDR5, which encodes a WD-40 repeat protein, is a direct target of SRY. EMSA experiments and ChIP assays showed that SRY could bind to the WDR5 gene promoter directly. Overexpression of SRY in LNCaP cells significantly increased WDR5 expression concurrent with histone H3K4 methylation on the WDR5 promoter. To specifically address whether SRY contributes to WDR5 regulation, we introduced a 4-hydroxy-tamoxifen-inducible SRY allele into LNCaP cells. Conditional SRY expression triggered enrichment of SRY on the WDR5 promoter resulting in induction of WDR5 transcription. We found that WDR5 was self regulating through a positive feedback loop. WDR5 and SRY interacted and were colocalized in cells. In addition, the interaction of WDR5 with SRY resulted in activation of Sox9 while repressing the expression of β-catenin. These results suggest that, in conjunction with SRY, WDR5 plays an important role in sex determination

Atomic Energy Commission Report AECD-4046

Report discussing progress made in metallurgy by the Ames Laboratory during the the term from October 1, 1950 to March 31, 1951