scholarly journals Durability Characterization of a High Performance Building Envelope with Vacuum Insulation Panels and Energy Recovery Ventilation

2021 ◽  
Author(s):  
Christopher Campbell
2018 ◽  
Vol 9 (2) ◽  
pp. 163-168 ◽  
Author(s):  
Á. Lakatos ◽  
I. Deák ◽  
U. Berardi

The development of high performance insulating materials incorporating nanotechnologies has enabled considerable decrease in the effective thermal conductivity. Besides the use of conventional insulating materials, such as mineral fibers, the adoption of new nano-technological materials such as aerogel, vacuum insulation panels, graphite expanded polystyrene, is growing. In order to reduce the thermal conductivity of polystyrene insulation materials, during the manufacturing, nano/micro-sized graphite particles are added to the melt of the polystyrene grains. The mixing of graphite flakes into the polystyrene mould further reduces the lambda value, since graphite parts significantly reflect the radiant part of the thermal energy. In this study, laboratory tests carried out on graphite insulation materials are presented. Firstly, thermal conductivity results are described, and then sorption kinetic curves at high moisture content levels are shown. The moisture up-taking behaviour of the materials was investigated with a climatic chamber where the relative humidity was 90% at 293 K temperature. Finally, calorific values of the samples are presented after combusting in a bomb calorimeter.


1984 ◽  
Vol 51 (01) ◽  
pp. 016-021 ◽  
Author(s):  
S Birken ◽  
G Agosto ◽  
B Lahiri ◽  
R Canfield

SummaryIn order to investigate the early release of NH2-terminal plasmic fragments from the Bβ chain of fibrinogen, substantial quantities of Bβ 1-42 and Bβ 1-21 are required as immunogens, as radioimmunoassay standards and for infusion into human volunteers to determine the half-lives of these peptides. Towards this end methods that employ selective proteolytic cleavage of these fragments from fibrinogen have been developed. Both the N-DSK fragment, produced by CNBr cleavage of fibrinogen, and Bβ 1-118 were employed as substrates for plasmin with the finding of higher yields from N-DSK. Bβ 1-42 and Bβ 1-21 were purified by gel filtration and ion-exchange chromatography on SP-Sephadex using volatile buffers. When the purified preparation of Bβ 1-42 was chromatographed on reverse-phase high performance liquid chromatography, two peaks of identical amino acid composition were separated, presumably due either to pyroglutamate or to amide differences.


1992 ◽  
Vol 57 (10) ◽  
pp. 2151-2156 ◽  
Author(s):  
Peter Chabreček ◽  
Ladislav Šoltés ◽  
Hynek Hradec ◽  
Jiří Filip ◽  
Eduard Orviský

Two methods for the preparation of high molecular weight [3H]hyaluronic acid were investigated. In the first one, hydrogen atoms in the molecule were replaced by tritium. This isotopic substitution was performed in aqueous solution using Pd/CaCO3 as the catalyst. In the second method, the high molecular weight hyaluronic acid was alkylated with [3H]methyl bromide in liquid ammonia at a temperature of -33.5 °C. High-performance gel permeation chromatographic separation method was used for the isolation and characterization of the high molecular weight [3H]hyaluronic acid. Molecular weight parameters for the labelled biopolymers were Mw = 128 kDa, Mw/Mn = 1.88 (first method) and Mw = 268 kDa, Mw/Mn = 1.55 (second method). The high molecular weight [3H]hyaluronic acid having Mw = 268 kDa was degraded further by specific hyaluronidase. Products of the enzymatic depolymerization were observed to be identical for both, labelled and cold biopolymer. This finding indicates that the described labelling procedure using [3H]methyl bromide does not induce any major structural rearrangements in the molecule.


2021 ◽  
Vol 13 (9) ◽  
pp. 4640
Author(s):  
Seung-Yeoun Choi ◽  
Sean-Hay Kim

New functions and requirements of high performance building (HPB) being added and several regulations and certification conditions being reinforced steadily make it harder for designers to decide HPB designs alone. Although many designers wish to rely on HPB consultants for advice, not all projects can afford consultants. We expect that, in the near future, computer aids such as design expert systems can help designers by providing the role of HPB consultants. The effectiveness and success or failure of the solution offered by the expert system must be affected by the quality, systemic structure, resilience, and applicability of expert knowledge. This study aims to set the problem definition and category required for existing HPB designs, and to find the knowledge acquisition and representation methods that are the most suitable to the design expert system based on the literature review. The HPB design literature from the past 10 years revealed that the greatest features of knowledge acquisition and representation are the increasing proportion of computer-based data analytics using machine learning algorithms, whereas rules, frames, and cognitive maps that are derived from heuristics are conventional representation formalisms of traditional expert systems. Moreover, data analytics are applied to not only literally raw data from observations and measurement, but also discrete processed data as the results of simulations or composite rules in order to derive latent rule, hidden pattern, and trends. Furthermore, there is a clear trend that designers prefer the method that decision support tools propose a solution directly as optimizer does. This is due to the lack of resources and time for designers to execute performance evaluation and analysis of alternatives by themselves, even if they have sufficient experience on the HPB. However, because the risk and responsibility for the final design should be taken by designers solely, they are afraid of convenient black box decision making provided by machines. If the process of using the primary knowledge in which frame to reach the solution and how the solution is derived are transparently open to the designers, the solution made by the design expert system will be able to obtain more trust from designers. This transparent decision support process would comply with the requirement specified in a recent design study that designers prefer flexible design environments that give more creative control and freedom over design options, when compared to an automated optimization approach.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chris Sundahl ◽  
Junki Makita ◽  
Paul B. Welander ◽  
Yi-Feng Su ◽  
Fumitake Kametani ◽  
...  

AbstractSuperconducting radio-frequency (SRF) resonator cavities provide extremely high quality factors > 1010 at 1–2 GHz and 2 K in large linear accelerators of high-energy particles. The maximum accelerating field of SRF cavities is limited by penetration of vortices into the superconductor. Present state-of-the-art Nb cavities can withstand up to 50 MV/m accelerating gradients and magnetic fields of 200–240 mT which destroy the low-dissipative Meissner state. Achieving higher accelerating gradients requires superconductors with higher thermodynamic critical fields, of which Nb3Sn has emerged as a leading material for the next generation accelerators. To overcome the problem of low vortex penetration field in Nb3Sn, it has been proposed to coat Nb cavities with thin film Nb3Sn multilayers with dielectric interlayers. Here, we report the growth and multi-technique characterization of stoichiometric Nb3Sn/Al2O3 multilayers with good superconducting and RF properties. We developed an adsorption-controlled growth process by co-sputtering Nb and Sn at high temperatures with a high overpressure of Sn. The cross-sectional scanning electron transmission microscope images show no interdiffusion between Al2O3 and Nb3Sn. Low-field RF measurements suggest that our multilayers have quality factor comparable with cavity-grade Nb at 4.2 K. These results provide a materials platform for the development and optimization of high-performance SIS multilayers which could overcome the intrinsic limits of the Nb cavity technology.


2021 ◽  
Vol 11 (7) ◽  
pp. 3212
Author(s):  
Noa Miguez ◽  
Peter Kidibule ◽  
Paloma Santos-Moriano ◽  
Antonio O. Ballesteros ◽  
Maria Fernandez-Lobato ◽  
...  

Chitooligosaccharides (COS) are homo- or hetero-oligomers of D-glucosamine (GlcN) and N-acetyl-D-glucosamine (GlcNAc) that can be obtained by chitosan or chitin hydrolysis. Their enzymatic production is preferred over other methodologies (physical, chemical, etc.) due to the mild conditions required, the fewer amounts of waste and its efficiency to control product composition. By properly selecting the enzyme (chitinase, chitosanase or nonspecific enzymes) and the substrate properties (degree of deacetylation, molecular weight, etc.), it is possible to direct the synthesis towards any of the three COS types: fully acetylated (faCOS), partially acetylated (paCOS) and fully deacetylated (fdCOS). In this article, we review the main strategies to steer the COS production towards a specific group. The chemical characterization of COS by advanced techniques, e.g., high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and MALDI-TOF mass spectrometry, is critical for structure–function studies. The scaling of processes to synthesize specific COS mixtures is difficult due to the low solubility of chitin/chitosan, the heterogeneity of the reaction mixtures, and high amounts of salts. Enzyme immobilization can help to minimize such hurdles. The main bioactive properties of COS are herein reviewed. Finally, the anti-inflammatory activity of three COS mixtures was assayed in murine macrophages after stimulation with lipopolysaccharides.


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