Barrier Test

Explosive State Density gJcc Barrier Length, mm Projectile Velocity m/sec 

In Fig 17 is illustrated a test in which a sheet explosive (donor) was detonated on top of a bomb case filled with one of the above HE s, serving as acceptor. The bomb case served here as a gap and it was possible to produce in the HE, under certain conditions, a Igw-order reaction instead of detonation 

The results showed that by carefully adjusting the donor chges and the thickness 

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Cover designs The capillary barrier test section was installed in November 1999. From the surface downward, it is composed of 6 in. of topsoil, 18 in. of moderately compacted silt, and 24 in. of sandy gravel. The cover was seeded in March 2000 with a mixture of grasses, forbs, and shrubs, including bluegrass, wheatgrass, alfalfa, and prickly rose shrubs. A conventional composite cover test section was also constructed at the site. 

In Vitro Membrane Barrier Test Method for Skin Corrosion, Draft New Guideline (May 2004)... 

In vitro membrane barrier test method for skin corrosion (Draft)... 

The OECD and EU have developed specific test guidelines for in vitro/ex vivo testing of skin corrosion, the Transcutaneous Electrical Tesistance (TER) Test and the Human Skin Model Test (see Table 4.7). In fact, the EU Annex V, B.40 test guideline includes the two adopted OECD in vitro tests for skin corrosion (TG 430 and 431). OECD has also developed a third test guideline for skin corrosion, the In Vitro Membrane Barrier Test this test guideline has not yet been adopted. 

The membrane barrier test is composed of two components, a synthetic macromolecular bio-barrier and a chemical detecting system (CDS). The basis of the test method is that it detects membrane barrier damage caused by corrosive test substances after the application of the test substance to the surface of the artificial membrane barrier presumably by the same mechanism(s)... 

Table I. Sodium Ion Barrier Test Results for Polyimide and Silicon Nitride Films.

Barrier Tests and Their Comparison with Shooting Tests. In the shooting test, a cylindrical projectile of Al, steel, etc is shot against a cylindrical sample of explosive in such a manner that one of the plane surfaces of projectile strikes a plane surface of the expl sample. The pressure developed on coaxial impact can be calcd from the expression ... 

A minimum (critical) velocity of projectile was found to be lower than for corresponding barrier test... 

In the barrier test, a cylindrical sample of explosive is separated from a charge of expl known as donor by a harrier, which is a thick disk of Al, br ass or other metal. In this test, the donor creates a shock wave in the barrier, which in turn gives rise to an impact pressure at the contact surface... 

Comparing the shooting- with barrier test, Lundborg found that a linear relationship exists betw critical velocity of A1 projectile (d—15 mm) and length of A1 barrier (d=21 mm). This confirmed results previously reported in Refs 1-5... 

Refs 1) S.M. Brown E.G. Whitbread, Collin tmlCentreNatlRechScientSaint-Louis, France, 28 Aug-2 Sept, 1961 (Shooting and barrier tests) 2) C.H. Johansson T. 

Sjolin, Explosivst 9, 165(1961) (Barrier test) 3) Ibid, Arkiv for Fysik, Stockholm 24, 559 (1963) (Barrier test) 4) E. Eldth et al, Explosivst 11, 97(1963) (Shooting test)... 

N. Lundborg, Explosivst 12, 269(1964) (Barrier and shooting tests). 6) N. Lundborg, 4thONRSympDeton(1965), 432-34 (Comparison between shooting and barrier tests). 

The Gap Test, sometimes called Barrier Test or Booster Test, was first suggested by H. Muraour in MAF 12, 559(1933), but the first systematic study of the phenomenon was done by G. Herzberg R. Walker, Nature 161, 647(19-48). Since that time many expls labs both in the US and abroad have adopted and standardized it as a practical test of sensitivity. The apparatus used by... 

Initiation by Projectile Impact is a complicated process which depends on a combination of shock initiation, impact initiation and hot fragment initiation effects. For fast projectile impact, shock initiation effects are predominant. With slow projectiles the initiation resembles Impact Initiation. Further complications are introduced if the impacting projectiles are hot a special case where the explosive is part of the projectile is the so-called Susan Test—see Barrier Tests Their Comparison with Shooting Tests in Vo 4, pp D145-147 and Detonation (and Explosion) Experimental Procedures in Vol 4, pp 333-335... 

Barrier tests and their comparison with shooting tests 4 D145... 

Over the years a panel of methods has been published for testing different properties of the SC barrier (Table 37.1). The combination of tests, employing the application of chemical probes to the skin and the measurement of skin responses with new bioengineering read-out systems allows to measure changes in barrier properties with high sensitivity and reliability. A subjective selection of skin barrier tests will be discussed further in this chapter. 

This test is used to evaluate the toxicity of a material in vitro or an extract of a material used in a device. Several different tests have been used and have produced a spectmm of biocompatibility assessments on the same material (20-22). The tests used measure the viability of cells in contact with a material or an extract of a material. A variety of cell lines can be used however, a modified fibroblast line is usually the gold standard. Some tests used include 1) direct cell culture, 2) agar diffusion testing, 3) filter diffusion testing, and 4) barrier testing (22). 

The followmg summarizes the studies of electrokinetic barrier tests that have been done in the last 10 years or so. 

Figure 16.19. Schematic diagram of the barrier test (Reeve, 2007).

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