Opaque Component Research Articles

Validation of the simplified heat conduction model of EN ISO 52016-1

The issue of improving the building energy efficiency led to the development of calculation methods for the building energy performance assessment. To overcome the low accessibility to detailed input data, the recently introduced EN ISO 52016-1 hourly method is based on assumptions and simplifications chosen to allow a sufficient accuracy in the outcomes with a low amount of input data. Among these assumptions, a simplified mass distribution in the envelope components is considered. In the present work, the hypothesis of the simplified heat conduction model introduced by the EN ISO 52016-1 technical standard and an improved solution provided by its Italian National Annex were evaluated. In particular, the accuracy in the prediction of the internal surface temperature was assessed in comparison with a detailed finite difference conduction algorithm. The validation was performed for 5 opaque component test cases, covering a wide range of areal heat capacity values, by considering both internal and external thermal constraints (e.g. variation of the air temperature). For the structures and boundary conditions considered, results reveal that the standard algorithm allows to predict the internal surface temperatures with a valuable level of accuracy compared to the finite difference algorithm.

A lack of constraints on the cold opaque H i mass: H i spectra in M31 and M33 prefer multicomponent models over a single cold opaque component

ABSTRACT Previous work has argued that atomic gas mass estimates of galaxies from 21-cm H i emission are systematically low due to a cold opaque atomic gas component. If true, this opaque component necessitates a $\sim 35{{\ \rm per\ cent}}$ correction factor relative to the mass from assuming optically thin H i emission. These mass corrections are based on fitting H i spectra with a single opaque component model that produces a distinct ‘top-hat’ shaped line profile. Here, we investigate this issue using deep, high spectral resolution H i VLA observations of M31 and M33 to test if these top-hat profiles are instead superpositions of multiple H i components along the line of sight. We fit both models and find that ${\gt}80{{\ \rm per\ cent}}$ of the spectra strongly prefer a multicomponent Gaussian model while ${\lt}2{{\ \rm per\ cent}}$ prefer the single opacity-corrected component model. This strong preference for multiple components argues against previous findings of lines of sight dominated by only cold H i. Our findings are enabled by the improved spectral resolution (0.42 ${\rm km\, s^{-1}}$), whereas coarser spectral resolution blends multiple components together. We also show that the inferred opaque atomic ISM mass strongly depends on the goodness-of-fit definition and is highly uncertain when the inferred spin temperature has a large uncertainty. Finally, we find that the relation of the H i surface density with the dust surface density and extinction has significantly more scatter when the inferred H i opacity correction is applied. These variations are difficult to explain without additionally requiring large variations in the dust properties. Based on these findings, we suggest that the opaque H i mass is best constrained by H i absorption studies.

Mineralogical indicators of Mercury's hollows composition in MESSENGER color observations

AbstractEarly during MErcury Surface Space ENvironment GEochemistry, and Ranging (MESSENGER)'s orbital mission, the Mercury Dual‐Imaging System imaged the landform called hollows on the two craters Dominici and Hopper, using its Wide‐Angle Camera with eight narrowband color filters ranging from 433 to 996 nm. An absorption feature centered in the MDIS 629 nm filter is evident in reflectance spectra for Dominici's south wall/rim hollows. A different absorption feature found in photometry of Dominici's center hollows extends through the MDIS 828 nm filter. Hollows in Hopper exhibit a weaker spectral absorption feature than that observed in Dominici's center. At Dominici, we postulate that fresher hollows‐hosting material in the wall/rim was exposed to the space environment through a process of slumping of the overlying material. With time, local and global processes darken the hollows and change or mix the surface mineralogy, so that the spectral signature evolves. The hollows could contain low‐density MgS and an opaque component, potentially derived from background material.

Mercury surface composition: Integrating petrologic modeling and remote sensing data to place constraints on FeO abundance

A significant opaque component in Mercury’s crust is inferred based on albedo and spectral observations. Previous workers have favored iron–titanium bearing oxide minerals as the spectrally neutral opaque. A consequence of this hypothesis is that Mercury’s surface would have a high FeO content. An array of remote sensing techniques have not provided definitive constraints on the FeO content of Mercury’s surface. However, spectral observations have not detected a diagnostic 1 μm absorption band and have thus limited the FeO in coexisting silicates to <2 wt.% FeO. In this paper, we assess equilibrium among oxide and silicate minerals to constrain the distribution of iron between opaque oxides and silicates under a variety of environmental conditions. Equilibrium modeling is favored here because the geologic process that produced Mercury’s low-albedo intermediate terrain must have occurred globally, which favors a common widespread igneous process. Based on our modeling, we find that iron-rich ilmenite cannot occur with silicates that do not display a 1 μm absorption feature unless plagioclase abundances are high. However, such high plagioclase abundances are precluded by Mercury’s low albedo. Incorporating equilibrium crystallization modeling with spectral and albedo constraints we find the iron abundance of Mercury’s intermediate terrain is ⩽10 wt.% FeO. This intermediate iron composition matches constraints provided by visible albedo and total neutron absorption observed by MESSENGER. In fact, the total neutron absorption of mixtures of oxide, plagioclase, olivine and pyroxene for the oxide abundances estimated for Mercury, favor Mg-rich members of the ilmenite–geikielite solid-solution series. This work offers compositional constraints for Fe, Ti, and Mg that will be testable by various MESSENGER instrument data sets after it begins its orbital mission.

Characterisation of the inhomogeneity of sol–gel-derived SiO2–CaO bioactive glass and a strategy for its improvement

Sol–gel derived bioactive glasses are one of the most promising materials for bone regeneration. The nanostructure of the glasses is critical regarding their interaction with the physiological environment. Composition is one of the most important factors affecting the nanostructure. In this study, inhomogeneity (a translucent component surrounded by an opaque component) was found within sol–gel derived bioactive glass monoliths (70 mol% SiO2 and 30 mol% CaO) produced by a standard procedure. The nanostructure and composition of the two components were characterised by electron microscopy, nitrogen sorption, secondary ion mass spectroscopy, X-ray fluorescence and solid state nuclear magnetic resonance. Results showed that calcium concentration and nanoscale porosity were much higher in the opaque region than in the translucent component. This is believed to be caused by calcium nitrate accumulation on the outer surface of the monoliths during the drying stage of the sol–gel process. The homogeneity of monoliths was successfully improved by using Teflon moulds. These findings are important for the large scale commercial production of homogeneous sol–gel glasses.

Polarization of the L[CLC]y[/CLC]α Line from an Anisotropically Expanding H [CSC]i[/CSC] Shell in Primeval Galaxies

We compute the polarization of the Lyα photons emerging from an anisotropically expanding and optically thick medium, which is expected to operate in many Lyα-emitting primeval objects, including damped Lyα absorbers and Lyman break galaxies. In the case of a highly optically thick medium, the escape of resonance-line photons is achieved by a large number of local resonant scatterings followed by a small number of damping-wing scatterings. We show that some polarization can develop because wing scatterings are coupled with strong spatial diffusion that depends on the scattering geometry and kinematics. The case of a slab with a finite scattering optical depth and an expansion velocity of ~100 km s-1 is investigated. When the typical scattering optical depth τ104, it is found that the emergent Lyα photons are linearly polarized with a degree of polarization up to 0.1 in the direction perpendicular to the slab plane. We subsequently investigate the polarization of the Lyα photons emerging from a hemispherical shell obscured partially by an opaque component, and we obtain ~5% of the polarization. We propose that the polarimetry of Lyα emission may provide important clues to the geometrical and kinematical structures of the H I shells in primeval galaxies and nearby starburst galaxies.

Effect of the Position of the Heat Insulation Layer in the Opaque Component on the Heating Period

The aim of this article is to introduce an approach which can be used for the determination of the appropriate position of the heat insulation layer in the opaque component from the heating period viewpoint. The proposed approach has been applied for living rooms have different opaque component alternatives in Istanbul region aiming to determine the appropriate position of the heat insulation layer. For this purpose, firstly, the boundaries of the heating periods are determined by basing on the lowest comfort value of the indoor air temperature and the outdoor air temperature for different opaque component alternatives. Secondly, the boundaries of the heating period are compared. As the result of the comparison, the opaque component alternative which provides the shortest heating period is qualified as the most appropriate one and the position of the heat insulation layer in this opaque is qualified as appropriate.

Comparison study of two different testing methodologies used to characterize an opaque solar component

The work described in this paper was aimed at comparing two different testing methodologies, set up in order to define performance properties and reliability of passive or hybrid solar components. The former facility is based on the use of outdoor real-size Test Cells, designed to simulate a conventional living environment with a thermal mass distributed approximately in the same way as in a real dwelling. The latter uses an indoor real-size test cell reproducing a common piece of a dwelling; such a cell can assume various spatial arrangements and simulate in a cyclic way any temperature conditions and solar input on the walls under test. Experiments on a same opaque multilayer component were run with both facilities and the comparison of the obtained results are given; the good agreement of the efficiency values and the analysis of the most important working parameters of the tested component points out the effectiveness and the peculiarity of both methodologies.

Lexical decomposition of complex Kanji characters in Japanese readers

The study investigates the question whether during recognition of a complex Kanji character readers also access the meaning of opaque components of the character. The experiment used a speeded semantic-categorization task of two characters, in which readers were requested to decide whether two characters represented words related in meaning or not. The control pairs consisted of (a) graphically similar, but semantically unrelated, characters, and (b) a simple character and a complex character, of which the simple character was a component (part-whole relation), the two characters being again semantically unrelated. The critical pairs consisted of two characters unrelated in meaning, one of which contained an opaque component element related in meaning to the other character. A corresponding trial with English and its alphabetic system would be to ask a subject to decide whether boycott is related in meaning to girl or not. In this condition the subject is expected to give a No response, but if the pseudocomponent boy is activated, interference could occur. (If boy is recovered during recognition of the pseudocompound boycott, the appropriate No response for boycott-girl could become more difficult to take.) The result of the experiment indicated interference in all three conditions (graphically similar characters, part-whole related characters, and opaque-component related characters. Thus, in an analogous task with alphabetic material, it would be more difficult to say No about the existence of a semantic relation between (a) tree and free, (b) boy and boycott, and (c) boycott and girl. The last result can be interpreted as offering evidence for the activation of the opaque component upon recognition of the complex character.

A spectral analysis of ordinary chondrites, S‐type asteroids, and their component minerals: Genetic implications

Three salient features of visible and infrared reflectance spectra of ordinary chondrites (OCs) and S‐type asteroids are (1) albedo at 0.56 μm, (2) continuum slope, and (3) depth of the electronic absorption band due to octahedrally coordinated Fe2+ in olivine and pyroxene. These quantities were numerically extracted from the spectra of 23 OCs representing all metamorphic grades and 39 S‐type asteroids to be plotted in a three‐dimensional coordinate system. The spectral characteristics of three OCs which were comminuted, melted, recrystallized, and recomminuted are also presented in the same format. The results show that although laboratory simulation of melt alteration in an asteroidal regolith does alter OC spectra, the spectral parameters of these altered meteorites do not change enough to leave the parametric region defined by “unaltered” OC spectra. When the region containing the 39 S‐asteroid spectra is compared with that of the altered and unaltered OCs, it is found that not one of the OCs falls within the S‐asteroid region. The differences may be largely attributed to spectral differences between the respective metallic components. The range of S‐asteroid parameters is then compared with potential pure “end‐member” components most likely to result from magmatic differentiation of a chondritic protoasteroid: olivine, orthopyroxene, clinopyroxene, and Fe,Ni meteorite metal (alternatively represented by the M‐asteroids). It is found that the S‐asteroid array is consistent with random mixtures of the differentiated components except for a notable dominance of the spectral characteristics of the opaque (metallic) component. These results suggest that the M‐asteroids may form a composition continuum with the S‐asteroids. We discuss a scenario consistent with this analysis and with the Bell et al. theory of the geological structure of the asteroid belt. Ordinary chondritic protoasteroids of all sizes were probably the dominant primary condensates in the inner portion of the main asteroid belt. These were later heated by electromagnetic induction or by 26Al nuclide decay. As a result, the smaller ones were subjected to various degrees of metamorphism, while the larger ones were subjected to large‐scale magmatic differentiation. Petrological domains of the S‐asteroids (beneath a mixed regolith) may be large and supply achondrites, irons, and stony irons to Earth rather than well‐mixed breccias of these components. The (smaller) OC protoasteroids may still be abundant in the asteroid belt but, if small enough to escape differentiation, may also be small enough to escape Earth‐based identification.

Effect of Fiber Translucency on the Color of Blends of Precolored Fibers

Colored fibers can be blended together to create a spectrum of formulated yarn colors much like a paint formulator creates custom paint colors by blending dispersions of individual pigments. Unlike paint formulations, however, it is not possible to obtain a completely homogenized, uniform color with fibers because they remain separate entities on a macroscopic scale. When viewed under conditions that permit spatial or temporal integration of the discrete colors by the eye, one might expect the colors to combine much the way, for example, colored dots do on a television screen. This would require a simple weighted average or additive sort of color mixing mathematics, . but fiber blend colors follow much more closely the mathematics of subtractive color mixing, specifically the two-constant Kubelka-Munk theory. Simple experiments were performed to provide a better understanding of the color mixing mechanism operable in blends of differently colored fibers and a visual demonstration of that mechanism. The experiments show that both visual and spectrophotometric responses are linearly (additively) related to the component yarn colors in the blend only in the special cases of opaque component fibers or translucent fibers where there is no fiber overlap. For overlapping translucent fibers, the original component yarn colors form a mix according to the mathematics of the two-constant Kubelka-Munk theory, which is then additively integrated into the final blended yarn color. The two-constant Kubelka-Munk theory can be used over a wide range of fiber transparencies and degrees of overlap and can even approximate the color of opaque or non-overlapping fiber blends. Additive mixing mathematics, on the other hand, deviates rapidly from the actual visual or spectro photometric response as fiber translucency or overlap increases.

Interstellar molecules.

The study of interstellar molecules broadly includes two areas of interest. One area uses the unique ability of molecules to act as probes of the physical conditions in the cold, dense, visually opaque component of the interstellar medium. The physical properties of this and other components of the interstellar medium are summarized. The other area deals with the chemistry of interstellar molecules, recent aspects of which are emphasized in this review. Gas-phase chemistry, shock chemistry, and grain surface chemistry are discussed in the context of recent observations. No present observations suggest that surface reactions are relevant, but neither can they be ruled out. Ion-molecule reactions are clearly operative, at least for the simpler species. Chemical isotope fractionation is reviewed, and it is concluded that the complexities of the chemistry allow no cosmological conclusions to be drawn from observations of deuterium in interstellar molecules, while the presence of 13C in interstellar molecules permits an estimate of the 12C/13C ratio which is consistent with the current concepts of the nucleosynthesis history of the Galaxy. Possible connections between interstellar molecules and the early molecular history of the solar system are discussed.

Structural and chemical asymmetry of the calcium-transporting membranes of the sarcotubular system as revealed by electron microscopy

The calcium-transporting membrane of the sarcotubular system appears as a triple-layered asymmetric structure with a total thickness of about 60 A after fixation with osmium tetroxide or with glutaraldehyde followed by osmium tetroxide. In the vesicles that are formed upon isolation of the membrane, the peripheral opaque membrane component is denser and thicker than the opaque component facing the interior of the vesicles. This pattern is also observed in the membranes of intact muscle. In experiments where the vesicles were incubated with the SH-reagent Hg-phenyl azoferritin, a close packing of ferritin particles at the outer surface of the vesicular membrane was observed. After treatment with NEM, which blocks the SH-groups, no ferritin was attached to the membranes and the vesicles were clustered together. When the SH-groups at the active sites which are specifically involved in the calcium transport were selectively protected with ATP before NEM treatment, the ferritin was packed at the outer membrane surface as in normal material. The results have been interpreted as indicating a preferred localization of the active sites involved in the calcium transport at the outer surface of the membrane. The distance between adjacent sites seems to correspond exactly to the resolution of the method using ferritin as SHlabeling reagent. In a second series of experiments vesicular preparations were sonicated or allowed to age as well as treated with distilled water or alkali solutions in order to expose the inner membrane surface to the ferritin compound. Also in these preparations the label was located almost exclusively at the outer surface of the membrane, indicating that fewer reactive sites are located at the inner than at the outer surface.

The ultrastructure of the capillary fenestrae in the adrenal medulla of the rat

A single-layered membrane that appears to be structurally highly organized has been observed to bridge capillary fenestrae in the rat adrenal medulla. The membrane measures about 20–30 A in thickness and is suspended from the peripheral opaque component of the triple-layered plasma membrane of the endothelial cell. In the central area of the membrane is a dense ring-like structure, the periphery of which contains some highly stained particles and which has a center similar in density to the rest of the membrane. In cross sections the innermost region can be seen to contain some stained material extending out perpendicularly to the plane of the membrane on both sides of the fenestrae. The diameter of the fenestra is about 500 A, the overall width of the central region being 150–200 A, and the light center being 50–100 A in diameter. The membrane structure is observed in the fenestrae, where it separates the capillary lumen from the pericapillary space. It is also observed in the walls of endothelial vesicles. The single-layered membrane is interpreted to be chemically different from the plasma membrane of the endothelial cell and to be nonlipid.

The layered, asymmetric structure of the plasma membrane in the exocrine pancreas cells of the cat

The plasma membrane of the exocrine pancreas cell has an asymmetric triple-layered structure which after fixation with osmium tetroxide as well as potassium permanganate and embedding in Vestopal is about 90–100 A thick. The membrane consists of a cytoplasmic opaque component which is 35–40 A thick and which is separated from a peripheral opaque component, about 25 A thick, by a light layer measuring about 30 A in width. This pattern is revealed after section staining with lead hydroxide or uranyl acetate. At all boundaries between closely packed cells the plasma membranes are either separated by a light interspace, with an average width of 60 A, or the peripheral plasma membrane components are fused, forming a single opaque middle layer. The cell boundaries may accordingly appear as a seven-layered or a five-layered structure. The cell boundaries form attachment zones of two different types. One type is always located close to the excretory ducts and has a five- or seven-layered appearance. The second type of attachment zone is characterized by a slight widening of the cell boundaries and the presence of opaque material in the interspace between the plasma membranes. The cytoplasmic components of the plasma membranes are closely associated with opaque material in the cytoplasm in the attachment zones.