Exterior Envelope

Outdoor air is generally less polluted than the system return air. However, problems with reentry of previously exhausted air occur as a result of improperly located exhaust and intake vents or periodic changes in wind conditions. Other outdoor contamination problems include contaminants from other industrial sources, power plants, motor vehicle exhaust, and dust, asphalt vapors, and solvents from construction or renovation. Also, heat gains and losses through the building envelope due to heat conduction through exterior walls, floor, and roof, and due to solar radiation and infiltration, can be attributed to effects from external sources. 

Beck, F. A., and Arasteh, D. (1992). Improving the Thermal Performance of Vinyl-Framed Windows. Proceedings of the ASHRAE/DOE/BTECC Conference on the Thermal Performance of the Exterior Envelopes of Buildings V, Cleaiwater Beach, FL. 

HRVs are non-enveloped viruses of icosahedral overall shape [44]. Located on the exterior of the viral capsid are three structural proteins (VPl, VP2 and VP3), each consisting of an eight-stranded antiparallel -barrel. VP4 is found at the interface with the RNA inside the virus. A pocket factor is usually bound to a hydrophobic canyon binding site within the VPl -barrel. This lipid-like molecule is important for the stability of the capsid and has been... 

A porous particle contains many interior voids known as open or closed pores. A pore is characterized as open when it is connected to the exterior surface of the particle, whereas a pore is closed (or blind) when it is inaccessible from the surface. So, a fluid flowing around a particle can see an open pore, but not a closed one. There are several densities used in the literature and therefore one has to know which density is being referred to (Table 3.15). True density may be defined as the mass of a powder or particle divided by its volume excluding all pores and voids. True density is also referred to as absolute density or crystalline density in the case of pure compounds. However, this density is very difficult to be determined and can be calculated only through X-ray or neutron diffraction analysis of single-crystal samples. Particle density is defined as the mass of a particle divided by its hydrodynamic volume. The hydrodynamic volume includes the volume of all the open and closed pores. Practically, the hydrodynamic volume is identified with the volume included by the outer surface of the particle. The particle density is also called apparent or envelope density. The term skeletal density is also used. The skeletal density of a porous particle is higher than the particle one, since it is the mass of the particle divided by the volume of solid material making up the particle. In this volume, the closed pores volume is included. The interrelationship between these two types of density is as follows (ASTM, 1994 BSI, 1991) ... 

ArillaTE Having an exterior covering or appendage on the seeds of certain plants, which develops after fertilization as an outgrowth of the funicle and envelops the seed. 

This is an interconnected network of flattened or spherical vesicles and tubules found in the cytoplasm of eukaryotic cells. These structures are enveloped by a membrane that separates the endoplasmic reticulum cavities or cisternae. The cisternae constitute a network of channels that go through the cytoplasm and regulate the transport of various cell products, generally to the exterior environment. In some cells the cisternae also serve as a storage area. There are two types of endoplasmic reticulum granular (or rough) and smooth. 

The three-dimensional reconstruction from a tilt series of a negatively stained cell envelope revealed a dome-shaped morphological imit with a wide opening toward the cytoplasmic membrane and a narrow opening to the exterior at the apex [125]. This design resembles that of Haloferax volcanii [121] and, to a lesser extent, that of Sulfolobus... 

The flow of air through the building envelope—may be from the outside of a building to the interior or from the interior to the exterior. 

In high-pressure agglomeration, another interlocking mechanism may occur if a mixture of rigid and plastic materials is compacted. In this situation, the plastic component flows into recesses and, more generally, envelopes the exterior structure of harder particles, thus producing a strong structural bond that resembles the effect of a matrix binder (see also Section 8.1). 

The second argument seems obscure to the contemporary scientist. Vernadsky (1994, p. 321) writes that a similarity of compounds of Ae exterior envelopes of celestial bodies like Earth, Sun and stars" show the essential (cosmic) character of life. 

Under certain circumstances, many bacteria produce capsules outside their ceU envelopes. Capsules are usually made of polysaccharide however, some Bacillus capsules are composed of D-glutamic acid polypeptide. Certain Gram positive bacteria, most notably strains of Bacillus and Clostridium, produce modified ceUs (endospores) capable of surviving in adverse environments. Spore PG is found between an inner and outer membrane and differs from that in the normal vegetative cell muramic acid is mostly in the lactam form the spore PG has fewer peptide cross-links and the ceU exterior is coated with keratin. The spore also contains large quantities of calcium dipicolinate, a substance involved in microbial heat resistance. 

The vulnerability curve is constructed from the vulnerability matrix. The vulnerability curve for any apartment unit type is the plot of the mean or average damage ratio vs. wind speed. The exterior envelope vulnerability curves for different apartments are shown in Fig. 5. It is apparent from the graph that units in open buildings are more vulnerable than in closed buildings and that comer units are more vulnerable than middle units. 

Where there are protrusions on the exterior surface, the protrusion should be ignored in determining the 1 m distance, except in the case of a finned package, in which case the measurement may be made at 1 m distance from the external envelope of the package. 

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