Saturated Atmosphere Research Articles

A PV-gradient related quantity in moist atmosphere and its application in the diagnosis of heavy precipitation

In this paper, a PV-gradient related parameter-the second-order potential vorticity (SPV) is generalized into a non-uniformly saturated atmosphere to involve the PV-gradient into precipitation diagnosis, assuming that PV gradient is more capable of describing the whole structure of the air mass boundaries than other single element gradients. The newly derived second-order moist potential vorticity (SMPV), which is defined as the dot product of the generalized vorticity vector and three-dimensional gradient of a conserved form of generalized potential vorticity (GPV), keeps the conserved property as SPV in the frictionless, moist adiabatic atmosphere. Nevertheless, due to the complex calculation of SMPV, a non-conservative form of SMPV (NSMPV) is subtracted from SMPV, which is defined as the dot product of vorticity vector and three-dimensional gradient of GPV by involving the baroclinic vorticity. The capability of the NSMPV on diagnosing and detecting heavy precipitation is examined for a heavy rainfall case, with GPV as a comparison. A typical scale analyses in this case shows that GPV is mainly a coupling of static stability and vertical vorticity, while NSMPV contains static stability, vorticity enstrophy and their vertically inhomogeneity. Due to these information, both GPV and NSMPV show strong anomalies over the precipitation region, by reflecting the cyclonic shear and large vertical variations of temperature and humidity in the lower troposphere. However, GPV also appears strong, wide anomalies out of the precipitation region while NSMPV does not. In addition, due to the vertical gradient of vorticity enstrophy and static stability contained in NSMPV, it also has a reflection on the invasion of cold, dry air in the near-surface layer, which is seen to be a triggering mechanism of the strong precipitation. This indicates that NSMPV perform better than GPV in detecting heavy rainfall and are powerful on distinguishing between precipitation and non-precipitation region. A long time-series analyses over China further verify a steady performance of NSMPV on diagnosing precipitation, which means NSMPV may be used as a precipitation indicator as well as GPV in the future.

Carbonation acceleration of calcium hydroxide nanoparticles: induced by yeast fermentation

Carbonation of Ca(OH)2 nanoparticles and consolidation of limestone are accelerated by high humidity and a yeast fermentation system that supplies a saturated atmosphere on CO2, H2O vapor and ethanol during 28 days. Nanoparticles were analyzed by X-ray diffraction and differential thermal analyses with thermogravimetry. Spectrophotometry, scanning electron microscopy analyses, and hydric and mechanical tests were also performed in stones specimens. Samples exposed to the yeast environment achieve 100 % relative CaCO3 yield, whereas at high humidity but without the yeast and under laboratory environment, relative yields of 95 % CaCO3 and 15 % CaCO3 are, respectively, reached, with white crusts and glazing left on the stone surfaces when the nanoparticles are applied at a concentration of 25 g/l. The largest increase in the drilling resistance and surface hardness values with slight increase in the capillarity absorption and desorption coefficients and with lesser stone color changes are produced at a concentration of 5 g/l, in the yeast system environment. This especially happens in stone specimens initially with bimodal pore size distributions, more amounts of pores with diameters between 0.1 and 1 µm, higher open porosity values and faster capillary coefficients. An inexpensive and reliable method based on water and yeast–sugar solution is presented to speed up carbonation of Ca(OH)2 nanoparticles used as a consolidating product to improve the mechanical properties of decayed limestone from archaeological and architectural heritage.

Dynamic surface tension of С10ЕО8 at the aqueous solution/hexane vapor interface as measured by bubble pressure tensiometry

Abstract The dynamic surface tension of aqueous solutions of C10EO8 at the interfaces with air and saturated hexane vapor was measured by the maximum bubble pressure tensiometer BPA for adsorption times t ≥ 0.01 s. It can be shown that the dynamic surface pressure of C10EO8 solutions in a saturated hexane atmosphere increases at short adsorption times with increasing surfactant concentration. The theory of diffusion controlled adsorption of two surfactants from the water and gas phases, respectively, was used for data analysis. The obtained experimental results agree with a model based on a reorientation of the C10EO8 molecules, assuming a strong intermolecular interaction between hexane and C10EO8 molecules in the surface layer. Alternatively, an additional enhancement of C10EO8 adsorption activity can be assumed due to the presence of hexane molecules at the interface.

Preparation and characterization of C/SiO2/SiC aerogels based on novolac/silica hybrid hyperporous materials

Novolac/silica hybrid gels (N/SiO2) are synthesized using the sol–gel polymerization method under a solvent-vapor saturated atmosphere, followed by an ambient-pressure drying technique. Moreover, prepared N/SiO2 aerogels are converted to carbon/silica (C/SiO2) and carbon/silica/silicon carbide (C/SiO2/SiC) nanocomposite aerogels through pyrolysis and carbothermal reduction at 800 and 1500°C, respectively. X-ray diffraction studies reveal the formation of graphite, cristobalite and β-SiC portions in the structure of prepared C/SiO2/SiC aerogels. Mercury porosimetry and scanning electron microscopy results demonstrate that the structural characteristics of fabricated nanocomposite aerogels retained after heat treatment steps. Thermogravimetric analysis and compressive strength measurements are used to investigate thermal and mechanical properties of prepared aerogels, respectively. The maximum oxidation rate temperature increased from 588°C for carbon aerogel to about 750°C for C/SiO2/SiC aerogels. The thermal conductivity coefficient of C/SiO2 and C/SiO2/SiC aerogels at room temperature are about 0.058 and 0.121 (Wm−1K−1), respectively. Compressive strength of C/SiO2/SiC aerogels is in the range of 1.8–2.3MPa. This is very impressive as the compressive strength of novolac/silica aerogels is in the range of 0.2–1.4MPa.

“All It Is Is Light”: Projections and Volumes, Artistic Light, and Pipilotti Rist’s Feminist Languages and Logics of Light

This article explores the feminist language of light developed in the work of video artist Pipilotti Rist. Feminist studies of Rist’s work have tended to analyze the symbolic content of her projections, in this article I want to reorient that analytic lens to examine the critical force of the light that constitutes her projections, together with the saturated color atmospheres that she creates. By way of the photosensitivity of Luce Irigaray I explore how Rist’s work develops a feminist language of light – focusing in particular on the logics of surfaces and volumes. The language of light Irigaray builds, to which the idea of texture is key, is an important part of her wider project. A project which seeks to offer an alternative to what she sees as phallocentric accounts of the intersection of sight and vision, and the relationship of subjects and objects. Tracing the evolution of Irigaray’s own thinking, the article concludes with some thoughts on what an ethics built from light might look/feel like.

The Introduction of Specific Water and Maximum Airborne Specific Water & the Improvement of Dynamic Equations on Non-Uniform Saturated Moist Atmosphere

To eliminate the irrational supposition that condensed liquid water always falls immediately, specific water m and maximum airborne specific water mm are introduced into the dynamic framework on non-uniform saturated moist atmosphere (m is the ratio of the airborne liquid water mass to the moist air mass in unit cubage moist air, mm is its maximum value with , , and are airborne coefficient, vertical velocity and saturated specific humidity respectively). The balance equation between water vapor and airborne liquid water is derived. From the balance equation, a new formula of precipitate rate is got. The analysis shows that in the air stream with some upward vertical velocity ( ), the condensed liquid water can precipitate under the condition with (q is specific humidity) and only, otherwise it is detained in the air and becomes airborne liquid water. Not only does precipitating liquid water contain condensed liquid water, but also contains converged and existing airborne liquid water. Following above discussion, improved dynamic equations on non-uniform saturated moist atmosphere are provided.

The Effect of Resin and Monoterpenes on Spore Germination and Growth in Fusarium circinatum.

Resin obtained from Pinus radiata and five monoterpene components of resin (limonene, α-pinene, β-pinene, camphene, and myrcene) were tested to determine their effects on mycelial growth and germination and survival of spores of Fusarium circinatum, the cause of pitch canker in pine, and F. temperatum, which is interfertile with F. circinatum but not pathogenic to pine. Averaged across all treatments, F. temperatum sustained the greatest reduction in radial growth (16.9±0.02% of control). The greatest reduction in dry weight also occurred in F. temperatum (11.7±0.01% of control), and all isolates of F. circinatum were significantly less affected (P<0.05). Spore germination rates in a saturated atmosphere of monoterpenes were relatively high for all tested isolates but, when placed in direct contact with resin, spore survival was significantly greater for F. circinatum than for F. temperatum. Our results are consistent with the hypothesis that greater tolerance of resin is one factor distinguishing F. circinatum from the nonpathogenic F. temperatum. However, differential tolerance of monoterpene components of resin is not sufficient to explain the observed variation in virulence to pine in F. circinatum.

Assessment of soybean (Glycine max) vigour by the seed leachate conductivity assay

Conductivity of seed leachates is inversely correlated with germination and growth of soybean, &lt;i&gt;Glycine max&lt;/i&gt; (L.) Merr., at low temperatures. It is concluded that the seed leachate conductivity assay can be employed to assess soybean seed vigour. Cold tolerance of soybean can markedly be enhanced by increasing the hydration level of the seeds to at least 20% by means of exposure of the seeds to HRH (water saturated atmosphere) for 4 days. It is suggested that increased vigour following HRH exposure is due to re-establishment of the cell membrane integrity in the course of exposure.

Fabrication of Highly Ordered Two-Dimensional Graphene Arrays on Patterned Substrate

We report a facial and straightforward method to fabricate highly ordered two-dimensional graphene arrays. A monolayer molecule pattern with alternative hydrophilic/hydrophobic wetting property was first formed by using micro-contact printing (μCP) and self-assembly techniques. Water droplets were condensed on the hydrophilic areas under saturated water atmosphere, which could be used to construct the ordered graphene arrays. The optical microscopy and atom force microscopy results indicate that ring and porous arrays of graphene can be obtained with low and high concentration of graphene solutions, respectively. Without the water droplet template, graphene patterns with square structure were produced.

Single-crystal tetrathiafulvalene microwire arrays formed by drop-casting method in the saturated solvent atmosphere

We developed a drop-casting method to grow the well-aligned single-crystal tetrathiafulvalene (TTF) microwire arrays with success ratio as high as 86%. The key improvement over the earlier study is that the substrate is placed in an apparatus which is filled with the saturated solvent vapor at room temperature. The saturated solvent atmosphere ensures stable environment and adequate time to form the arrays with high success ratio, and to dramatically improve the crystalline quality. Combined with the optimized concentration, the highly ordered single-crystal TTF microwire arrays are obtained. Based on these microwire arrays, the assembly of devices can be easily realized in one step. These results show the potential of this facile method to form the high-quality arrays, and the assemblies of nanoscale circuits for fundamental studies and future applications.

Enhancing the water stability of Al-MIL-101-NH2 via postsynthetic modification.

The resistance of metal-organic frameworks towards water is a very critical issue concerning their practical use. Recently, it was shown for microporous MOFs that the water stability could be increased by introducing hydrophobic pendant groups. Here, we demonstrate a remarkable stabilisation of the mesoporous MOF Al-MIL-101-NH2 by postsynthetic modification with phenyl isocyanate. In this process 86 % of the amino groups were converted into phenylurea units. As a consequence, the long-term stability of Al-MIL-101-URPh in liquid water could be extended beyond a week. In water saturated atmospheres Al-MIL-101-URPh decomposed at least 12-times slower than the unfunctionalised analogue. To study the underlying processes both materials were characterised by Ar, N2 and H2 O sorption measurements, powder X-ray diffraction, thermogravimetric and chemical analysis as well as solid-state NMR and IR spectroscopy. Postsynthetic modification decreased the BET equivalent surface area from 3363 to 1555 m(2) g(-1) for Al-MIL-101-URPh and reduced the mean diameters of the mesopores by 0.6 nm without degrading the structure significantly and reducing thermal stability. In spite of similar water uptake capacities, the relative humidity-dependent uptake of Al-MIL-101-URPh is slowed and occurs at higher relative humidity values. In combination with (1) H-(27) Al D-HMQC NMR spectroscopy experiments this favours a shielding mechanism of the Al clusters by the pendant phenyl groups and rules out pore blocking.

One-stage thermo-hydro treatment (THT) of hardwoods: an analysis of form stability after five soaking-drying cycles

AbstractA newly developed thermo-hydro treatment (THT) for use in a one-stage heat treatment process was examined by focusing on the form stability-related properties of European aspen (Populus tremula), birch silver (Betula pendula), and gray alder (Alnus incana). In particular, wood specimens were subjected to THT in a saturated steam atmosphere in a pilot-scale autoclave heated between 140 and 180°C for 1–3 h. Several parameters of untreated and treated samples after several soaking and drying cycles were compared, namely, the changes in the volumetric swelling, swelling in the radial and tangential directions, cell wall total water capacity, and anti-swelling efficiency (ASE). Due to repeated wetting in the cyclic water submersion-drying test, the original ASE of 73% decreased to 65% (180°C for 1 h), and the original ASE of 33% decreased to 5% (140°C for 1 h). Wood modified at 170°C presented good results that were not significantly lower than wood treated at higher temperatures while consuming less energy to deliver ASE improvement and was selected as optimum. To increase the ASE by 1%, the amount of energy consumed was decreased by 41%, 39%, and 17% compared with the treatment regimes of 160°C for 1 h, 160°C for 3 h, and 180°C for 1 h, respectively. The new THT regime led to improved long-term dimensional stability due to the cross-linking of cell wall polymers, which resulted in increased cell wall rigidity.

On the hypothetical utilization of atmospheric potential energy

Atmospheric potential energy is typically divided into an available and a nonavailable part. In this article a hypothetical utilization of a fraction of the nonavailable potential energy is described. This part stems from the water vapor that can be converted into the liquid phase. An energy gain results when the potential energy of the condensate relative to a reference height exceeds the energy necessary to condensate the water vapor. It is shown that this can be the case in a saturated atmosphere without convective available potential energy. Finally, simulations with the numerical cloud model HURMOD are performed to estimate the usability of the device in practice. Indeed, a positive energy output results in a simulation with immediate gathering of the condensate. On the contrary, potential energy gained falls significantly short of the necessary energy for forming the condensate when a realistic cloud microphysical scheme allowing re-evaporation of condensate is applied. Taken together it can be concluded that, a utilization of atmospheric potential energy ishypothetically possible but the practical realization is probably not feasible.

Anelastic and Compressible Simulation of Moist Deep Convection

Abstract Anelastic and compressible solutions are compared for two moist deep convection benchmarks, a two-dimensional thermal rising in a saturated moist-neutral deep atmosphere, and a three-dimensional supercell formation. In the anelastic model, the pressure applied in the moist thermodynamics comes from either the environmental hydrostatically balanced pressure profile in the standard anelastic model or is combined with nonhydrostatic perturbations from the elliptic pressure solver in the generalized anelastic model. The compressible model applies either an explicit acoustic-mode-resolving scheme requiring short time steps or a novel implicit scheme allowing time steps as large as those used in the anelastic model. The consistency of the unified numerical framework facilitates direct comparisons of results obtained with anelastic and compressible models. The anelastic and compressible rising thermal solutions agree not only with each other but also with the previously published compressible benchmark solution based on the comprehensive representation of moist dynamics and thermodynamics. In contrast to earlier works focusing on the formulation of moist thermodynamics, the compatibility of the initial conditions is emphasized and its impact on the benchmark solutions is documented. The anelastic and compressible supercell solutions agree well for various versions of anelastic and compressible models even for cloud updrafts reaching 15% of the speed of sound. The nonhydrostatic pressure perturbations turn out to have a negligible impact on the moist dynamics. Numerical and physical details of the simulations, such as the advection scheme, spatial and temporal resolution, or parameters of the subgrid-scale turbulence, have a more significant effect on the solutions than the particular equation system applied.

Interfacial reactions between humic-like substances and lateritic clay: Application to the preparation of “geomimetic” materials

The aim of this study was to understand the mechanisms responsible for the strengthening of “geomimetic” materials, especially the chemical bonding between clay and humic substances. The mineral matter is lateritic clay which mainly consists in kaolinite, goethite, hematite and quartz. The other starting products are fulvic acid (FA) and lime. The preparation of these geomimetic materials is inspired from the natural stabilization of soils by humic substances occurring over thousands of years. The present process involves acidic and alkaline reactions followed by a curing period of 18days at 60°C under a water saturated atmosphere. The acceleration of the strengthening process usually observed in soils makes this an original process for treatment of soils. The consolidation of the “geomimetic” materials could result from two major phenomena: (i) chemical bonding at the interface between the clay particles and iron compounds and the functional groups of the fulvic acid, (ii) a partial dissolution of the clay grains followed by the precipitation of the cementitious phases, namely calcium silicate hydrates, calcium aluminate hydrates and mixed calcium silicum and aluminum hydrates. Indeed, the decrease of the BET specific area of the lateritic clay after 24h of reaction with FA added to the structural reorganization observed between 900 and 1000°C in the “geomimetic” material, and to the results of adsorption measurements, confirm the formation of organo-ferric complexes [1]. The presence of iron oxides in clay, in the form of goethite, appears to be another parameter in favor of a ligand exchange process and the creation of binding bridges between FA and the mineral matter. Indeed all faces of goethite are likely to be involved in complexation reactions whereas in lateritic clay only lateral faces could be involved [2]. The results of the adsorption experiments realized at a local scale will improve our understandings about the process of adsorption of FA on lateritic clays and its involvement in the strengthening process of materials.

A generalized frontogenesis function and its application

With the definition of generalized potential temperature, a new generalized frontogenesis function, which is expressed as the Lagrangian change rate of the magnitude of the horizontal generalized potential temperature gradient, is derived. Such a frontogenesis function is more appropriate for a real moist atmosphere because it can reflect frontogenesis processes, in which the atmosphere in a frontal zone is typically characterized by neither completely dry nor uniform saturation. Furthermore, by derivation, the expression of generalized frontogenesis function includes both temperature and humidity gradients, which is different from and superior to the traditional frontogenesis function in moist processes, which also uses equivalent potential temperature. Diagnostic studies of real cases are performed and show that the generalized frontogenesis function in non-uniformly saturated moist atmosphere indeed provides a useful tool for frontogenesis, compared to using the traditional frontogenesis function. The new frontogenesis function can be used in situations involving either a strong temperature or moisture gradient and is closely correlated with precipitation.

Cohesion of Granular Matter in Subzero Humidity

Atmospheric humidity has an important effect on granular media by increasing the cohesion of powders and grains and is hence of significance for the industrial processing of finely dispersed materials. Water bridges around the contact points of hydrophilic particles lead to an increased cohesion at higher humidities, and this has been studied at ambient temperatures in model systems. Because liquid water bridges may form below the freezing point of water, we decided to study the cohesion of millimeter-size glass beads in humid atmospheres at subzero temperatures. We find that the angle of repose of a pile of glass beads in a saturated atmosphere of water vapor below 0 °C decreases as the temperature falls, and closely mirrors the behavior as the humidity at room temperature is reduced from saturation; that is, the angle of repose of the glass beads is similar for water bridges that are of a similar size. These results show that both temperature and moisture determine the cohesion of granular media in subz...

Investigation of the effect of sol concentration on the microstructure and morphology of Novolac hyperporous

Novolac hyperporous materials were successfully synthesized using sol–gel polymerization of Novolac resin with hexamethylenetetramine (HMTA) catalyst in the solvent vapor saturated atmosphere, followed by subcritical drying. Mercury porosimetry results showed that these materials had large pore volume, more than 1cm3/g. SEM micrographs showed that these materials formed strongly cross-linked aggregates. Therefore, these results demonstrated that these materials would be termed as hyperporous materials.Novolac hyperporous materials can be either crushed or invaded by mercury during mercury porosimetry experiments. In this work, six samples with different initial sol concentration were examined. It has been shown here that a sample with higher porosity exhibited two volume variation mechanisms successively; compaction followed by intrusion, when submitted to mercury porosimetry that real result could be obtained by applying Pirard's collapse model below the pressure of transition, Pt, and Washburn's intrusion theory above Pt. Low porosity sample showed the collapse under mercury pressure only and no transient pressure could be observed. It means mercury does not penetrate the pore network, but the whole material is densified. Microstructure of these hyperporous materials directly influences mechanism changing from collapsing to intrusion.

Analysis of stability parameters in relation to precipitation associated with pre-monsoon thunderstorms over Kolkata, India

The upper air RS/RW (Radio Sonde/Radio Wind) observations at Kolkata (22.65N, 88.45E) during pre-monsoon season March–May, 2005–2012 is used to compute some important dynamic/thermodynamic parameters and are analysed in relation to the precipitation associated with the thunderstorms over Kolkata, India. For this purpose, the pre-monsoon thunderstorms are classified as light precipitation (LP), moderate precipitation (MP) and heavy precipitation (HP) thunderstorms based on the magnitude of associated precipitation. Richardson number in non-uniformly saturated (R i *) and saturated atmosphere (R i ); vertical shear of horizontal wind in 0–3, 0–6 and 3–7 km atmospheric layers; energy-helicity index (EHI) and vorticity generation parameter (VGP) are considered for the analysis. The instability measured in terms of Richardson number in non-uniformly saturated atmosphere (\(R_{i}^{\mathrm {\ast } })\) well indicate the occurrence of thunderstorms about 2 hours in advance. Moderate vertical wind shear in lower troposphere (0–3 km) and weak shear in middle troposphere (3–7 km) leads to heavy precipitation thunderstorms. The wind shear in 3–7 km atmospheric layers, EHI and VGP are good predictors of precipitation associated with thunderstorm. Lower tropospheric wind shear and Richardson number is a poor discriminator of the three classified thunderstorms.

Quels lasers et quels paramètres pour quelles lésions : discussion intéractive de cas cliniques

Novolac hyperporous materials were successfully synthesized using sol–gel polymerization of Novolac resin with hexamethylenetetramine (HMTA) catalyst in the solvent vapor saturated atmosphere, followed by subcritical drying. Mercury porosimetry results showed that these materials had large pore volume, more than 1 cm3/g. SEM micrographs showed that these materials formed strongly cross-linked aggregates. Therefore, these results demonstrated that these materials would be termed as hyperporous materials.Novolac hyperporous materials can be either crushed or invaded by mercury during mercury porosimetry experiments. In this work, six samples with different initial sol concentration were examined. It has been shown here that a sample with higher porosity exhibited two volume variation mechanisms successively; compaction followed by intrusion, when submitted to mercury porosimetry that real result could be obtained by applying Pirard's collapse model below the pressure of transition, Pt, and Washburn's intrusion theory above Pt. Low porosity sample showed the collapse under mercury pressure only and no transient pressure could be observed. It means mercury does not penetrate the pore network, but the whole material is densified. Microstructure of these hyperporous materials directly influences mechanism changing from collapsing to intrusion.