Physical, chemical and spectral properties of leaf surfaces of Berberis aquifolium (Pursh.)

Abstract The leaves of Berberis aquifolium (Pursh.) exhibit either diffuse or specular (shiny) reflection, depending on the variety, but in no case are the leaves obviously glaucous. The dull-surfaced leaves were less wettable than the glossy ones. Using scanning electron microscopy it was determined that the diffuse reflection was due to tubular crystals of wax 250 nm in diameter. The crystals were primarily composed of 19-nonacosanol, a 29-carbon secondary alcohol, as determined by gas chromatography-mass spectrometry. The chemical constituents of the wax underlying the tubes appeared to be the same as those of the wax from glossy leaves, with 29-carbon and 31-carbon n-alkanes and n-heptacosanol as major constituents. The reflection spectra of dull-surfaced (diffuse reflection) or glossy (specular reflection) leaves were the same, as were those of leaves with different amounts of epicuticular wax. Removing the epicuticular wax with chloroform did not change the spectrum.     

Surfactant-induced breakthrough effects during the operation of two-phase biocatalytic membrane reactors

Surface-active components, both reactants and products, are frequently encountered in two-phase, aqueous-organic, biocatalytic reactions, When such reaction are carried out in a membrane reactor, employing a membrane selectively wetted by one of the two reactants, changes in the content of these surfactants- as a consequence of the progress of the reaction-can lead to wetting transitions at the two membrane-liquid interfaces as a result of adsorption of the tenside. This can lead to a decrease in the pressure required to cause the, initially, nonwetting phase to break through the membrane. Such effects render difficult the operation of two-phase membrane bioreactors. Hence, it is necessary to make a careful selection of the membrane material and type by considering factors such as UF versus MF and low MWCO versus high MWCO to enable the reactor to be operated without breakthrough, but without significantly compromising the reaction rates that can be maintained.The phenomena leading to breakthrough effects are discussed in this paper, and experimental results for the hydrolysis of ethyl laurate by lipase from Candida rugosa in a batch flat sheet membrane reactor are presented with the reactor operated with a variety of membranes. An experimental result showing the decrease in the pressure required to cause breakthrough of the organic phase (for the system ethyl laurate-lauric acid-water) as the content of the highly surface-active lauric acid in the organic phase is increased is also presented for an asymmetric, hydrophilic meta-aramid ultrafiltration membrane. (c) 1994 John Wiley & Sons, Inc.     

Patterned Wettability Surface for Competition‐Driving Large‐Grained Perovskite Solar Cells

Novel photovoltaic perovskite solar cells (PSCs) with high‐efficient photovoltaic property are largely in thrall to the uncertain perovskite grain size and inevitable defects. Here, inspired by the competitive growth between tree and grass in the forest system, a competitive perovskite grain growth approach via micro‐contact print (MicroCP) method (CD disk as templates) for printing wettability‐patterned substrate is proposed, aiming to achieve large‐grained perovskite and avoid discontinuous perovskite films caused by the low wettability of substrates. A MicroCP process is employed to construct a patterned wettability surface for the perovskite competitive growth mechanism on the electrode surface. This approach modifies the substrates quickly, ensures the uniform coverage of perovskite due to the function of ‐NH₂ and Pb²⁺ bonds, and converts the perovskite films composed of small grains and pinholes into high‐quality perovskite films, free from pinholes and made up of large grains, resulting in efficiencies over 20% for the MicroCP PSCs.     

Effect of nanostructure on wettability on copper surface: a molecular dynamic study

Molecular dynamics simulations (MDS) are employed to investigate the effects of interatomic interaction and nanostructure on wettability of water on a copper plate. In the nano scale, these simulation results showed that the contact angle gradually increases with the decreasing of the reaction parameters, which results in the decreasing of free energy on the solid-liquid interface. Therefore, it leads to that the hydrophilic material is turned into hydrophobic, which fits the results that the wettability is changed by low surface energy materials in macro scale. Furthermore, the contact angles on smooth and rough surfaces are 87° and 71.6°, respectively. That is to say that the hydrophilic will increase for hydrophilic material due to the existence of one-layer structure; it agrees with the experimental results in macro scale.     

Modifications of the leaf surface structures of Quercus ilex L. in open, naturally CO2-enriched environments

Two Italian CO₂ springs allowed us to study the long-term effect of a 350–2600 μ mol mol^–1 increase in CO₂ concentrations on the surface structures of leaves of Quercus ilex L. Carbon dioxide increased the quantity of cuticular waxes, above an apparent threshold of 750 μ mol mol^–1 CO₂. Leaf wettability was not modified by CO₂ concentrations. Reduction in stomatal frequency was observable up to 750 μ mol mol^–1 CO₂, the slope being almost the same as that estimated for the increase in CO₂ concentration from pre-industrial times to the present. At higher concentrations, CO₂ seemed to exert no more impact on stomatal frequency.     

Simulation of the Influence of Surface Wettability on Viscous Fingering Phenomenon in Porous Media

Fingering phenomena are common occurrence in the natural world. It generally takes place when a less viscous fluid displacesa more viscous fluid typically in porous media. Nowadays, such phenomena have extensively been studied due to itsimportance in many industrial fields. In this paper, the effects of surface wettability on finger pattern are studied and simulatednumerically by the Lattice Boltzmann method (LBM). The displacement efficiency is investigated by using two parameters,namely, the breakthrough time and the areal sweep efficiency. The simulation has demonstrated that surface wettability willinfluence the finger pattern no matter the gravity is considered or not, but in the presence of gravity, the finger pattern is muchmore complicated and irregular due to the coexistence and competition of capillary force, viscous force and gravity.     

Capillary Effects on Natural Remobilization of Pools of Dense Non-Aqueous Phase Liquid Mixtures in Porous Media

The natural remobilization of an initially static mixed dense non-aqueous phase liquid (DNAPL) pool due to dissolution was demonstrated by (Roy et al. 2002 Roy, J. W., Smith, J. E. and Gillham, R. W. 2002. Natural remobilization of multicomponent DNAPL pools due to dissolution. J. Contam. Hydrol., 59: 163–186. [Crossref], [PubMed], [Web of Science ®] [Google Scholar], 2004 Roy, J. W., Smith, J. E. and Gillham, R. W. 2004. Laboratory evidence of natural remobilization of multicomponent DNAPL pools due to dissolution. J. Contam. Hydrol., 74: 145–161. [Crossref], [PubMed], [Web of Science ®] [Google Scholar]) using a compositional mathematical model and laboratory experiments with open pools over a porous medium. The purposes of this study were to: a) demonstrate natural remobilization for a pool within porous media (as opposed to an open pool); and b) analyze the capillary effects associated with residual formation, a changing saturation profile, hysteresis, and aging, as these processes may reduce the potential for natural remobilization of pools in porous media. DNAPL pools comprised of tetrachloroethene and benzene were created within a zone of larger glass beads overlying smaller glass beads, in a water-saturated 2-D flow cell. In one case, remobilization occurred in the form of a DNAPL finger, after 56 days of flushing. In another case, no remobilization had occurred after 64 days of flushing, though the density increased by 430 kg m ^?3 and remobilization was predicted by the compositional model. Comparison of observations with model predictions suggest that contact angle hysteresis, related to an observed change in wettability, was the most significant contributing factor causing overprediction of the potential for natural remobilization.     

Analogies to demonstrate the effect of roughness on surface wettability

This article presents an analogy to illustrate the effect of surface roughness on surface wettability. I used a water-filled balloon to represent water droplet, a toothpick to represent surface roughness and Styrofoam as the surface. The analogies presented in this article will help visualize how roughness affects the wettability of the surface and therefore can be used to introduce surface wettability to high school students.