The Thermal Explosion Confined by a Constant Temperature Boundary: II— The Extremely Rapid Transient

In the industrial fabrication processes of density-graded closed-cell metallic foams, it is of great importance to control the solidification immediately after foams are formed so as to obtain the final products with well distributed density-graded pores and less defects. This paper presented an analytical work aiming to predict the solidification front of density-graded metallic foam under constant temperature boundary condition. Numerical simulations based on ideal density-graded circular pores demonstrated good agreement with the analytical solutions. The 2D porous morphology of a real density-graded aluminum foam was further reconstructed with microCT, on the basis of which the propagation of solidification front inside this real density-graded foam was numerically investigated. An equivalent shape factor for this real foam was calculated to provide an insight for the influence of different pore shapes on solidification. Compared with other pores, the solidification speed of elliptical pores (a common pore shape in real foams) is moderate, i.e., slower than circular pores but quicker than triangular pores for same porosity.

Download Full-text

Improvement in the Fock test for determining the reactivity of dissolving pulp

TAPPI Journal ◽

10.32964/tj12.11.21 ◽

2013 ◽

Vol 12 (11) ◽

pp. 21-26 ◽

Cited By ~ 39

Author(s):

CHAO TIAN ◽

LINQIANG ZHENG ◽

QINGXIAN MIAO ◽

CHRIS NASH ◽

CHUNYU CAO ◽

...

Keyword(s):

Moisture Content ◽

Sodium Hydroxide ◽

Constant Temperature ◽

Carbon Disulfide ◽

Testing Procedure ◽

Dissolving Pulp ◽

Water Bath ◽

Testing Conditions ◽

Pulp Sample ◽

Fock Reactivity

The Fock test is widely used for assessing the reactivity of dissolving pulp. The objective of this study was to modify the method to improve the repeatability of the test. Various parameters that affect the repeatability of the Fock test were investigated. The results showed that Fock reactivity is dependent on testing conditions affecting the xanthation between cellulose and carbon disulfide, such as the moisture content of the pulp sample, sodium hydroxide (NaOH) concentration, xanthation temperature, carbon disulfide dosage, and xanthation time. The repeatability of the test was significantly improved using the following modified testing procedure: air dried sample in the constant temperature/humidity room, xanthation temperature of 66°F (19°C) in a water bath, xanthation time of 3 h, NaOH concentration of 9% (w/w), and 1.3 mL carbon disulfide.

Download Full-text

ACTION OF ENZYME DIGESTED PITUITARY GLANDS OF THE SKIPPER-FROG ON THE OVULATION OF THE SAME

Acta Endocrinologica ◽

10.1530/acta.0.xxxiii0255 ◽

1960 ◽

Vol XXXIII (II) ◽

pp. 255-260 ◽

Cited By ~ 3

Author(s):

L. S. Ramaswami ◽

A. B. Lakshman

Keyword(s):

Pituitary Gland ◽

Constant Temperature ◽

Constant Temperature Bath ◽

Predominant Role ◽

Lower Vertebrates ◽

Pituitary Glands ◽

Stimulating Factor

ABSTRACT By using enzymes, the gonadotrophic factors in the skipper-frog pituitary glands have been selectively inactivated or destroyed. By incubating a known number of pituitary gland homogenate with ptyalin in a constant temperature bath for 5–6 h the follicle-stimulating factor is inactivated; with trypsin or pepsin, the luteinizing factor is inactivated. Bioassay on gravid skipper-frogs indicate that the ptyalin digested homogenate brings about profuse spawning while the trypsin or pepsin digested homogenates do not. When a combination of ptyalin digested and trypsin digested homogenates is injected into fresh gravid skipper-frogs, poor spawning is brought about. These experiments show that the luteinizing factor alone brings about more profuse spawning than when it is combined with the follicle-stimulating factor. It is likely, therefore, that in the lower vertebrates the luteinizing factor of the pituitary gland plays a more predominant role. The exact proportions in which the different dosages for the control and test animals are administered are also tabulated.

Download Full-text