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In cold-formed steel structural members, holes are sometimes provided in webs, or flanges, or both of beams and columns for duct work, piping, ease of handling, and for other purposes. The presence of such holes may result in a reduction in strength of individual component elements or the overall strength of the member, or in both. At present, only a limited amount of design information is available for relatively heavy steel sections with perforated elements; however, no provisions are included in the American Iron and Steel Institute specification for the design of cold-formed steel members with perforated elements. The structural behavior of cold-formed steel beams and columns with a single circular or square hole in the web or flange has been studied in this preliminary investigation. Design formulas subject to a limited scope have been developed from this study for possible determination of effective design width and load-carrying capacities.

A study was made on the use of the “Specification for the Design of Cold-Formed Steel Structural Members” of the American Iron and Steel Institute (AISI) for the design of steel members cold-formed from thick sheets and plates. Experiments were conducted to study the increase in yield point caused by the cold work of forming. The investigation indicates that the design formulas for determining the effective design width of stiffened elements and the allowable stress for unstiffened compression elements currently included in the AISI Specification can be conservatively used for sections cold-formed from thick sheets and plates. It was also found that the AISI design provision for computing corner yield point provides good results for thick steel sheets and plates having a sharp yielding stress-strain curve with a small plateau and for cold-rolled sheets and strip.

Excitation functions and mean recoil ranges have been measured for radioactive products resulting from the helium-ion bombardment of natural zirconium and targets which were isotopically enriched in ${\mathrm{Zr}}^{90}$. Helium-ion energies varied between 25 and 80 MeV. Products observed were ${\mathrm{Mo}}^{90}$, ${\mathrm{Nb}}^{90}$, ${\mathrm{Zr}}^{89}$, ${\mathrm{Zr}}^{88}$, ${\mathrm{Y}}^{88}$, ${\mathrm{Zr}}^{87}$, ${\mathrm{Y}}^{87}$, ${\mathrm{Zr}}^{86}$, and ${\mathrm{Y}}^{86}$. The excitation function was also measured for the production of ${\mathrm{Y}}^{87}$. The recoil ranges are compared with the range theory of Lindhard, Scharff, and Schiott to determine the energy ranges over which the production of the nuclide is consistent with major contributions from a compound-nucleus mechanism. Excitation functions for products with $A\ensuremath{\ge}87$ were compared with the statistical model to investigate the influence of shell structure on level densities. The level-density models used were those due to Newton and to Rosenzweig in addition to the standard Fermi-gas level density. Rosenzweig's model gave the best over-all agreement with the experimental results, with the standard Fermi-gas level density a close second. Several excitation functions were calculated using the $s$-wave approximation to estimate the effect of $\ensuremath{\gamma}$-ray de-excitation due to angular-momentum restrictions. Threshold position and excitation-function widths were found to agree quite satisfactorily with experimental values when this was done.

Tadpoles of the differentiated race of R. catesbeiana at standard stages 25-26 were reared at 30° for four months. Tadpoles at 20° served as controls. Histological examination of the gonads at the end of heat treatment showed sex transformation of ovaries toward testicular characteristics in various degrees. The transformation process involved degeneration of oocytes and appearance of rete cells which eventually induced the residual oogonia into spermatogonia and contributed to the formation of seminiferous tubules and vasa efferentia. This process was comparable to the indirect development of the testis of the undifferentiated sex race of the same species. Our findings of heat-induced sex reversal were essentially in accordance with the earlier works of Witschi and Yoshikura. However, some differences have been observed. The rate of sex transformation in this study was much slower than that of R. sylvatica and R. japonica because of the persistence of synaptenes in the ovaries of R. catesbeiana and consequently late appearance of rete cells. The resistance of synaptenes to heat was probably a function of temperature magnitude and/or inherent property of the species. The results support Witschi's theory of antagonism between female and male differentiators.

The following reaction cross sections have been measured using the activation method: 40 Ar(n, α) 37 S, 31±5 mb; 48 Ti(n, α) 45 Ca, 39±6 mb; 50 Ti(n, α) 47 Ca, 9.4±3 mb; 62 Ni(n, α) 59 Fe, 22±3 mb; 106 Cd(n, α) 103 Pd, 100±40 mb; 108 Cd(n, 2n) 107 Cd, 504± mb; 110 Cd(n, p) 110 Ag, 27±5 mb; 111 Cd(n, p) 111 Ag, 14±1.4 mb; 112 Cd(n, α) 109 Pd, 2.4±0.4 mb; 112 Cd(n, p) 112 Ag, 11±1 mb; 113 Cd(n, p) 113 Ag, 7.9±0.8 mb; 114 Cd(n, α) 111m Pd, 0.2±0.03 mb; 114 Cd(n, α) 111g Pd, 0.5±0.08 mb; 116 Cd(n, α) 113 Pd, 0.5±0.5 mb; 116 Cd(n, p) 116 Ag, 0.2±0.1 mb; 116 Cd(n, 2n) 115m Cd, 730±60 mb; 116 Cd(n, 2n) 115g Cd, 857±70 mb; and 206 Pb(n, α) 203 Hg, 2.7±0.5 mb. The results were found to be in fairly good agreement with the semi-empirical predictions of Gardner, Yu and Rosenblum.

Intact and thyroidless tadpoles of the sex semidifferentiated race of Rana catesbeiana were used in the experiments for evaluation of thyroid function on sex transformation from ovaries to testes. Tadpoles reared in water at 20°C showed spontaneous transformation irrespective of the presence or absence of the thyroids. About half of the tadpoles possessed normal ovaries; a quarter had ovaries transforming toward testes; and another quarter already had testes. At 30°C, thyroidless tadpoles, whether or not treated with T4, all showed transformation. All ovaries were transformed into testes completely or in various stages in between, demonstrating synergistic effect of gene action in spontaneous sex transformation and of temperature factor in heat-induced sex transformation. These results indicate that thyroid function does not interfere with spontaneous sex transformation at 20°C nor heat-induced sex transformation at 30°C. The latter finding is at variance with Yoshikura's suggestion that thyroxine helped heat to transform ovaries into testes.