High-Strength High-Efficiency Particulate Air Filters for Nuclear Applications

Mycobacterium tuberculosis (MTB) is transmitted through the air, and can be captured on ventilation air filters. People handling these filters may be exposed to infectious material. We studied the survival of strains of Mycobacterium on high efficiency particulate air (HEPA) filter material. We used a model ventilation system to evaluate survival over time of Mycobacterium chelonae and H37Ra (an avirulent stain of MTB) aerosolized and then captured on HEPA filter material. Survival curves for M. chelonae incubated at 55% and 75% RH under static conditions were not different with less than 4% survival at 24 hours. H37Ra was subjected to continuous airflow at the design airflow for the filter material following deposition on the HEPA filter material, and less than 0.1% of cells survived to 48 hours (RH not controlled). H37Ra was resistant to immobilized biocide (trimethoxysilylpropyl dimethyloctadecyl ammonium chloride) on HEPA filter material as well as the same biocide in solution. Finally, survival of H37Ra and virulent MTB strain (H37Rv) were not different following deposition onto HEPA filter material from liquid suspension and incubation under static conditions.

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Development of Self-Sensing Textile Strengthening System Based on High-Strength Carbon Fiber

Materials ◽

10.3390/ma11102062 ◽

2018 ◽

Vol 11 (10) ◽

pp. 2062

Author(s):

Marcin Górski ◽

Rafał Krzywoń ◽

Magdalena Borodeńko

Keyword(s):

Carbon Fiber ◽

Carbon Fibers ◽

High Efficiency ◽

High Strength ◽

Strain Gauges ◽

Building Structures ◽

Climatic Chamber ◽

Daily Cycle ◽

Temperature Changes ◽

Temperature And Humidity

The monitoring of structures is one of the most difficult challenges of engineering in the 21st century. As a result of changes in conditions of use, as well as design errors, many building structures require strengthening. This article presents research on the development of an externally strengthening carbon-fiber textile with a self-sensing option, which is an idea is based on the pattern of resistive strain gauges, where thread is presented in the form of zig-zagging parallel lines. The first laboratory tests showed the system’s high efficiency in the measurement of strains, but also revealed its sensitivity to environmental conditions. This article also presents studies on the influence of temperature and humidity on the measurement, and to separate the two effects, resistance changes were tested on unloaded concrete and wooden samples. The models were then placed in a climatic chamber, and the daily cycle of temperature and humidity changes was simulated. The research results confirmed preliminary observations of resistivity growths along with temperature. This effect is more visible on concrete samples, presumably due to its greater amount of natural humidity. The strain measurement with carbon fibers is very sensitive to temperature changes, and applications of this method in practice require compensation.

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Removal of Microbe-Carrying Particles by High Efficiency Air Filters in Cleanrooms

International Journal of Ventilation ◽

10.1080/14733315.2012.11683960 ◽

2012 ◽

Vol 10 (4) ◽

pp. 339-351

Author(s):

W. Whyte ◽

G. Green ◽

W. M. Whyte

Keyword(s):

High Efficiency ◽

Air Filters

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Rapid Clogging of High-Efficiency Particulate Air Filters During In-Cell Solvent Fires at Reprocessing Facilities

Nuclear Technology ◽

10.1080/00295450.2019.1620057 ◽

2019 ◽

Vol 206 (1) ◽

pp. 40-47

Author(s):

Takuya Ohno ◽

Shinsuke Tashiro ◽

Yuki Amano ◽

Ryoichiro Yoshida ◽

Hitoshi Abe

Keyword(s):

High Efficiency ◽

Air Filters

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Transverse Deformations and Structural Phenomenon as Indicators of Steel Fibred High-Strength Concrete Nonlinear Behavior

Advances in Materials Science and Engineering ◽

10.1155/2019/9147849 ◽

2019 ◽

Vol 2019 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Iakov Iskhakov ◽

Yuri Ribakov

Keyword(s):

High Strength Concrete ◽

High Efficiency ◽

Limit State ◽

Nonlinear Behavior ◽

High Strength ◽

Steel Fibers ◽

Ultimate Limit State ◽

Strength Concrete ◽

Brittle Behavior ◽

Ductile Behavior

As known, high-strength compressed concrete elements have brittle behavior, and elastic-plastic deformations do not appear practically up to their ultimate limit state (ULS). This problem is solved in modern practice by adding fibers that allow development of nonlinear deformations in such elements. As a rule, are applied steel fibers that proved high efficiency and contribute ductile behavior of compressed high-strength concrete (HSC) elements as well as the desired effect at long-term loading (for other types of fibers, the second problem is still not enough investigated). However, accurate prediction of the ULS for abovementioned compression elements is still very important and current. With this aim, it is proposed to use transverse deformations in HSC to analyze compression elements' behavior at stages close to ultimate. It is shown that, until the appearance of nonlinear transverse deformations (cracks formation), these deformations are about 5-6 times lower than the longitudinal ones. When cracks appear, the tensile stress-strain relationship in the transverse direction becomes nonlinear. This fact enables to predict that the longitudinal deformations approach the ultimate value. Laboratory tests were carried out on 21 cylindrical HSC specimens with various steel fibers content (0, 20, 30, 40, and 60 kg/m3). As a result, dependences of transverse deformations on longitudinal ones were obtained. These dependences previously proposed by the authors’ concept of the structural phenomenon allow proper estimation of the compressed HSC state up to failure. Good agreement between experimental and theoretical results forms a basis for further development of modern steel fibered HSC theory and first of all nonlinear behavior of HSC.

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