Glazing systems in solar architecture

Research into the various aspects of solar architecture has developed some new and interesting features. To improve the overall quality and efficiency, the system component-efficiency needs to be re-examined. If the system can be divided into several more effective parts then a new integrated structure can cope with increased system performance requirements.

Glass structural components have therefore been subjected to a research and development programme and the Hungarian Glass Works have agreed to produce line lenses—a special type of optical glass body—which can be incorporated into the structure of the building. This new glass product behaves like a concentrating solar collector and multiplies the thermal gain compared with a conventional energy collector.

The system can meet a variety of demands for hot water, including commercial, residential and industrial uses as well as in agriculture.     

FT–NIR as a determination method for reinforcement of polymer nanocomposites

Layered silicates as nanoscale fillers have a great potential in improving polymer material properties. Depending on the composite structure (agglomerated, intercalated, or exfoliated) a significantly higher level of reinforcement of the virgin polymer can be achieved with a very small amount of filler. The morphology of the composites is usually characterized by XRD and microscopic methods (e.g., transmission electron microscopy). But the level of reinforcement of nanocomposites is not always proportional to morphology (delamination level of the silicate layers). A new approach for characterizing the material reinforcement level as a consequence of melt quality is to correlate the results of extensional rheometry (level of melt strength) with those of near infrared (NIR) spectroscopy. The advantage of the NIR technique is the suitability for in‐line implementation by using quartz based optics and optical fibers for the signal transfer from the measuring probe to the NIR spectrometer. The presented results show a direct correlation between the reinforcement level determined by rheotens measurements and the data analyzed from off‐line NIR measurements. The results of the chemometric analysis of the NIR data shows that this in‐line capable optical method provides quantitative information on the quality of the nanocomposite. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of molecular structure and reinforcement on fatigue behavior of tough polypropylene materials

Molecular structure and reinforcement heavily influence the crack growth resistance of polypropylene materials. Aim of this study is to investigate the fatigue behavior of different unreinforced and reinforced tough polypropylene materials used for piping applications. Due to high resistance against crack growth, these materials cannot be tested in the application relevant quasi‐brittle failure mode within feasible amounts of time. In this work, the new cyclic cracked round bar test, developed for tough polyethylene materials, has been examined as a possible method to characterize this important type of failure mode in homo‐, random‐, and reinforced polypropylene. Even though molecular mass distribution, which is often used to explain differences in crack growth resistance of polymers, was similar for unreinforced materials, fatigue lifetimes differed greatly. The mismatch of molecular mass and fatigue lifetime was mainly attributed to the different buildup and morphology of the base polymer. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43948.     

Elevated pitting wear of injection molded polyetheretherketone (PEEK) rolls

The increased pitting wear of PEEK rolls applied as bearing elements in drawer guide rails was investigated. Similar to findings for PEEK gear wheels the increased pitting occurred only in the presence of lubricants. Simple assumptions found in literature to explain this effect for PEEK gear wheels could be disproved within this research. Moreover, high irreversible deformations during the rolling process of PEEK rolls which were observed in a previous study were shown to not influence the mechanical properties of the surface material significantly. Additionally, the chemical analysis of the tribological system with Raman spectroscopy excluded a chemical reason for the intensified pitting. A detailed microscopic analysis of unstressed PEEK rolls combined with microtome cuts of the surfaces showed distinct pre-cracks in the outermost surface region which were not visible to the naked eye. Assuming a crack growth mechanism that was strongly supported by the fluid pressure of grease enclosed in the surface pre-cracks the injection molding process was adapted in order to improve the surface quality of the PEEK rolls. By this way the fatigue lifetime of the latter was increased by a factor of 2–3 which was crucial for the practical application.     

Uniaxial nonlinear viscoelastic viscoplastic modeling of polypropylene

This paper presents the application of the Schapery viscoelastic and the Perzyna viscoplastic models to strain recovery data of polypropylene. In a previous study, the recovery of strain after monotonic uniaxial tensile loading was measured to gather information on the viscoelasticity and viscoplasticity. The viscoplastic strains from several load histories were determined and are used to calibrate the viscoplastic model. The parameters of the one-dimensional Schapery model are then found by nonlinear optimization using the strain recovery history. The prediction of stress relaxation and creep behavior is investigated.     

Effect of stabilization on creep crack growth in high‐density polyethylene

Polyolefins, particularly polyethylene, are known to fail via crack initiation and crack propagation when exposed to multiaxial long‐term static stresses at elevated temperatures. Using concepts of linear elastic fracture mechanics, this article describes and discusses the effects of stabilization on the kinetics of creep crack growth (CCG) in high‐density polyethylene (PE‐HD) and the failure micromechanisms involved. As for the influence of stabilization, six PE‐HD formulations (two polymer types, each with three stabilizer systems) were investigated. CCG initiation times and CCG rates were determined at 60 and 80°C in distilled water as functions of the crack tip stress field characterized by the stress intensity factor. Although no influence of the stabilizer type was found in either polymer type for CCG initiation times and CCG rates at high crack speeds, significant effects of the added stabilizer type and concentration were detected for low CCG rates. The observed phenomena were explained in terms of local aging processes in the immediate vicinity of the crack tip, which were controlled by the presence and content of various stabilizers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3191–3207, 2003     

Potent neutralization of primary HIV-1 isolates by antibodies directed against epitopes present in the V1/V2 domain of HIV-1 gp120

Although it is known that some human immune sera possess potent neutralizing activities for primary viruses, the identity of the target epitopes mediating this neutralization is unknown, and currently available immunogens have not been able to induce such activities. Using recombinant fusion glycoproteins expressing native V1/V2 domains of gp120 we have found that sera from a subset of HIV-1-infected humans contain antibodies that recognize broadly conserved V1/V2 epitopes. Such antibodies were isolated from one human serum by affinity chromatography on a column containing a V1/V2 fusion protein, and shown to efficiently neutralize several macrophage-tropic HIV-1 isolates. Rodents immunized with the purified V1/V2 fusion protein produced antibodies reactive with unrelated V1/V2 fusion proteins and with heterologous gp120s. V1/V2-specific immunoglobulins isolated from sera of these animals by affinity chromatography also possessed potent neutralization activity for several primary HIV-1 isolates. These results indicate that the V1/V2 domain of HIV-1 gp120 contains conserved epitopes that mediate potent neutralization of primary viruses, and suggest that subunit vaccines that efficiently induce such antibodies may provide protective humoral immunity against clinically relevant HIV-1 isolates.     

Thermoluminescence of ZnO

The thermoluminescent behavior of polycrystalline ZnO was studied as a function of the temperature and partial pressure of oxygen of the heat treatment. Two peaks were observed, a broad peak at about 150°K and a well defined peak at 182°K. Analysis of the data obtained from the high temperature peak is consistent with the existence of a defect complex involving a copper impurity at 0.4 eV and a zinc vacancy 2.4 eV below the conduction band.     

Primitive features by steering, quadrature, and scale

The impulse response of neurons in the visual cortex of the mammalian brain has been known for some time. How to make use of these as filters has led to many hypotheses. The response of a single filter is ambiguous because the result depends on stimulus type, contrast, position, orientation, and scale. We show that a set of quadrature filters at sparse positions can be constructed so that it is possible to disambiguate the 2D responses of the individual filters. Detecting edges is not the goal of the present work; rather, we seek to detect relevant edges. Thus, we make the assumption that at the scale of interest, a local image patch consists predominantly of an edge or a bar. When this patch is processed by five or seven oriented filters, one can compute the exact orientation and centroid position of the feature. When the set of filters is applied at two different scales, it is possible to distinguish edges from ridges and to identify the polarity, intensity, and width. It is also possible to find corners and blobs. These computations are stable under image shifts in position and orientation and can be made to subpixel resolution