Perimeter Seal Research Articles

Slumped IGU’s with large airspaces: engineering challenges and solutions

Aside from external cladding pressure loads that are always considered in IGU design, a variety of unique factors must also be addressed when analyzing the structural performance of a slumped IGU with a large air cavity. These factors include the volume of air within the cavity, the stiffness and strength of the outer and inner lites of glass, elevation changes between the glass fabrication facility and the building site, temperature changes over time, fluctuations in barometric pressure, and increased stress on the secondary structural perimeter seal. Appropriate deflection limits for mullions or other elements supporting the IGU must also be established due to the increased stiffness of the IGU resulting from the slumped glass geometry. Engineering challenges related to the design of slumped IGU’s will be highlighted and explained using Nike’s new retail flagship store in New York City, Nike House of Innovation 000, as a case study for a dynamic facade featuring custom carved and slumped insulating glass units. Principal analysis methods, testing procedures, and a summary of the various software tools used to evaluate the slumped IGU’s will be provided. The solutions shown will illustrate how the fundamental design and engineering approach taken for Nike can be successfully applied to other projects that incorporate slumped IGU’s into their facades.

Mechanical Reliability Calculations for the Thin Specialty Glass PV Solar Panels

This study provides important design guidance to the Photovoltaic (PV) solar panel development efforts using the finite element based computations of the PV module under the mechanical loadings. We consider specialty thin glass (Corning Eagle XG®) as superstrate of the PV module, while a standard tempered Soda-Lime-Silica Glass (SLG) is considered as bottom support. The reliability calculations for the module were performed based on the stress magnitudes obtained from the FEA computations. The PV solar panel considered in this study are supported by C-chanel rails that run along the longitudinal direction. The optimum values for the C-chanel rail support location and height were determined using FEA driven reliability calculations. A methodology involving back calculation of the limiting stresses from the reliability constraints is briefly discussed, that can save the time consuming FEA iterations and tedious post processing of FEA results thereafter to calculate reliability. Analysis shows that the best rail position is between 17% to 20% of the module width (L) from the edge. The channel located at close to L/5 from the free edges was found to give mechanical reliability of 99%. Rail height greater than or equal to 23.5 mm can be used to achieve 95% reliability for the heavy snow load test. Lower modulus encapsulants such as silicone decrease the stress on top glass Eagle EG (EXG) and increase the stress on SLG (bottom glass) to a bit over the temper stress level. The butyl perimeter seal has a minimal impact on glass stress levels.

A Spatial Accommodation by Neighboring Cells Is Required for Organ Initiation in Arabidopsis

Lateral root formation in plants can be studied as the process of interaction between chemical signals and physical forces during development. Lateral root primordia grow through overlying cell layers that must accommodate this incursion. Here, we analyze responses of the endodermis, the immediate neighbor to an initiating lateral root. Endodermal cells overlying lateral root primordia lose volume, change shape, and relinquish their tight junction-like diffusion barrier to make way for the emerging lateral root primordium. Endodermal feedback is absolutely required for initiation and growth of lateral roots, and we provide evidence that this is mediated by controlled volume loss in the endodermis. We propose that turgidity and rigid cell walls, typical of plants, impose constraints that are specifically modified for a given developmental process.

VERTICALLY COLLAPSIBLE BARRIER WITH IMPROVED SEALING

A vertically collapsible wall partition is comprised of a plurality of interconnected horizontal wall panels pivotally interconnected to one another and forming horizontal panel joints therebetween. The panels are operated by an overhead lifting mechanism. The wall panels each have opposed spaced-apart composite walls each having perimeter seals to provide acoustic sound damping. The composite walls are formed by a face sheet secured to a front face of a core material and a backer sheet is secured to core material with an insulation material secured to the back of the backer sheet. Top and bottom horizontal seals are secured to the wall partition top and bottom horizontal wall panels. The seals and joints of the horizontal wall panels are such as to exhibit improved acoustic performance.

Novel Structural Components of the Ventral Disc and Lateral Crest in Giardia intestinalis

Giardia intestinalis is a ubiquitous parasitic protist that is the causative agent of giardiasis, one of the most common protozoan diarrheal diseases in the world. Giardia trophozoites attach to the intestinal epithelium using a specialized and elaborate microtubule structure, the ventral disc. Surrounding the ventral disc is a less characterized putatively contractile structure, the lateral crest, which forms a continuous perimeter seal with the substrate. A better understanding of ventral disc and lateral crest structure, conformational dynamics, and biogenesis is critical for understanding the mechanism of giardial attachment to the host. To determine the components comprising the ventral disc and lateral crest, we used shotgun proteomics to identify proteins in a preparation of isolated ventral discs. Candidate disc-associated proteins, or DAPs, were GFP-tagged using a ligation-independent high-throughput cloning method. Based on disc localization, we identified eighteen novel DAPs, which more than doubles the number of known disc-associated proteins. Ten of the novel DAPs are associated with the lateral crest or outer edge of the disc, and are the first confirmed components of this structure. Using Fluorescence Recovery After Photobleaching (FRAP) with representative novel DAP::GFP strains we found that the newly identified DAPs tested did not recover after photobleaching and are therefore structural components of the ventral disc or lateral crest. Functional analyses of the novel DAPs will be central toward understanding the mechanism of ventral disc-mediated attachment and the mechanism of disc biogenesis during cell division. Since attachment of Giardia to the intestine via the ventral disc is essential for pathogenesis, it is possible that some proteins comprising the disc could be potential drug targets if their loss or disruption interfered with disc biogenesis or function, preventing attachment.

Giardia Flagellar Motility Is Not Directly Required to Maintain Attachment to Surfaces

Giardia trophozoites attach to the intestinal microvilli (or inert surfaces) using an undefined “suction-based” mechanism, and remain attached during cell division to avoid peristalsis. Flagellar motility is a key factor in Giardia's pathogenesis and colonization of the host small intestine. Specifically, the beating of the ventral flagella, one of four pairs of motile flagella, has been proposed to generate a hydrodynamic force that results in suction-based attachment via the adjacent ventral disc. We aimed to test this prevailing “hydrodynamic model” of attachment mediated by flagellar motility. We defined four distinct stages of attachment by assessing surface contacts of the trophozoite with the substrate during attachment using TIRF microscopy (TIRFM). The lateral crest of the ventral disc forms a continuous perimeter seal with the substrate, a cytological indication that trophozoites are fully attached. Using trophozoites with two types of molecularly engineered defects in flagellar beating, we determined that neither ventral flagellar beating, nor any flagellar beating, is necessary for the maintenance of attachment. Following a morpholino-based knockdown of PF16, a central pair protein, both the beating and morphology of flagella were defective, but trophozoites could still initiate proper surface contacts as seen using TIRFM and could maintain attachment in several biophysical assays. Trophozoites with impaired motility were able to attach as well as motile cells. We also generated a strain with defects in the ventral flagellar waveform by overexpressing a dominant negative form of alpha2-annexin::GFP (D122A, D275A). This dominant negative alpha2-annexin strain could initiate attachment and had only a slight decrease in the ability to withstand normal and shear forces. The time needed for attachment did increase in trophozoites with overall defective flagellar beating, however. Thus while not directly required for attachment, flagellar motility is important for positioning and orienting trophozoites prior to attachment. Drugs affecting flagellar motility may result in lower levels of attachment by indirectly limiting the number of parasites that can position the ventral disc properly against a surface and against peristaltic flow.

Efficient Cooling of Multiple Components in a Shielded Circuit Pack

Abstract We describe a technology in which multiple components inside a circuit pack shielded from electromagnetic interference (EMI) are efficiently cooled by individual heat sinks that protrude into an external airflow through openings in the lid of the shield. Compliant, electrically conductive gaskets are used to form perimeter seals between the bases of the heat sinks and the lid of the enclosure. The gaskets accommodate variations in the heights of the components and allow solid-to-solid contact in the thermal-grease-filled interface between the components and their heat sinks without compromising EMI shielding. This technology provides efficient cooling because the heat sinks can be tailored to the thermal loads of the individual components. Moreover, a set of small heat sinks presents a lower flow resistance to the cooling airflow than the conventional configuration of fins covering the entire lid of an EMI shield. We have examined the implementation of this solution by numerical modeling and by experiment. It leads to acceptable thermal performance, and lower flow resistance relative to the conventional approach. It may reduce cost and weight and it eases rework.

Method of Measuring Ultralow Water Vapor Permeation for OLED Displays

It is well known that proper encapsulation is crucial for the lifetime of organic LED (OLED) displays. With the development of better and better barrier coatings and perimeter seals, it has now become very desirable to be able to precisely measure the rate of water vapor and oxygen permeation through barrier coatings and perimeter sealing. This paper demonstrates a new permeation measurement method that uses tritium-containing water (HTO) as tracer materials. The theoretical detection limit is 2.4/spl times/10/sup -7/ g/(m/sup 2//spl middot/day).

A new method for measuring ultra-low water-vapor permeation for OLED displays

— It is well known that proper encapsulation is crucial for the lifetime of organic light-emit-ting-diode (OLED) displays. With the development of increasingly better barrier coatings and perimeter seals, it has now become very desirable to be able to precisely measure the rate of water-vapor and oxygen permeation through barrier coatings and perimeter sealing. This paper demonstrates a new permeation-measurement method that uses tritium-containing water (HTO) as a tracer material. The theoretical detection limit of this direct method is 2.4 × 10−8 g/(m2-day).

Field Sound Transmission Loss Tests of Movable Partitions for School Classrooms

Field sound transmission loss tests have been made on a number of movable partitions installed in the Chicago Laboratory School of the University of Chicago on an experimental basis. Installation and tests were supported by the Educational Facilities Laboratories, Inc., New York City, to obtain performance information. Partitions tested included individually movable panels with perimeter seals, accordion folding units, and a new, heavy curtain type incorporating woven lead thread. A 6-in. lightweight aggregate concrete block wall was included for comparison. Results indicate a range of performance from satisfactory to inferior for the purpose. The nine-frequency average of both noise reduction and sound transmission loss do not, however, rank order the units ia agreement with subjective judgment.

Measurement of Sound Transmission Through Door Seals

A small-scale test facility has been constructed for measuring the transmission of sound through slits typical of the crack around a door. The facility consists of an absorptive lined box of concrete block containing a sound source beamed toward the top. The box is covered with a pair of heavy sliding panels having a joint at the center line of the box. Samples of slit configurations, gaskets, etc., are inserted between the panels for measurement. The box is built in a reverberation chamber, and the sound power output W of the slit is measured together with the sound pressure p0 in the box immediately adjacent to the slit. The effective radiating length L of the slit is about 2 ft. The measurements yield a quantity tentatively called the “slit constant” K=W/L p1,2 where p12=p02/2 is the equivalent room average sound pressure for the source side. he quantity K can then be used to compute the equivalent transmission loss TL' of a slit or seal forming the perimeter of a panel of given dimensions. For a 3×7-ft door, TL', defined as the TL of a door which transmits the same total sound power as the perimeter seal, is about 8 db higher than 10 log 1/K, if K is evaluated in feet. Typical data on slit and gasket configurations are presented.