Wall Dissolution Research Articles

Modeling Thermal Treatment in Combination with Acid Treatment of a Multilayer Oil Reservoir

The problem of combined thermal and acid treatment in a multilayer crude-oil reservoir is examined for two-phase flows of fluid (water and crude oil) in a porous medium. A model in the form of a “bundle” of cylindrical capillaries of different radii is used to describe changes in the porosity and permeability of the porous medium as a result of chemical reaction between the acid and rock matrix, and the coalescence rate of the channels due to dissolution of pore walls is calculated based on the Smoluchowski equation. The recovery of crude oil in conventional flooding is compared with flooding with injection of a heat-transfer agent, and flooding using acid and the combination technology. It is shown that thermal treatment combined with acid treatment of a multilayer crude-oil formation provides the most effective oil production conditions.

Ruthenium Oxide‐Doped TiO2 Nanotubes by Single‐Step Anodization for Water‐Oxidation Applications

AbstractSingle‐step anodization in NH4F‐based ethylene glycol electrolyte containing KRuO4 and H2O led to the production of high‐aspect‐ratio TiO2 nanotubes (NTs) with a doping of ruthenium oxide. These NTs were successfully used as electrodes for water oxidation in KOH. This method offers homogenous incor poration of a small amount of ruthenium oxide (≈0.12 wt %) into 25 μm TiO2 nanotubes without the need for complicated facilities or steps. The addition of H2O into electrolytes is a key step for the stable adhesion of long‐length TiO2 NT films on a substrate. The tips of the TiO2 nanotubes prepared by this novel method are not easily dissolved by electrolyte because the walls of the nanotubes are thickened by a factor of more than two in response to the addition of KRuO4 and H2O. The longest nanotubular TiO2 with a doping of ruthenium oxide and no wall dissolution shows the largest current density in the oxygen‐evolution reaction.

A model for cell wall dissolution in mating yeast cells: polarized secretion and restricted diffusion of cell wall remodeling enzymes induces local dissolution.

Mating of the budding yeast, Saccharomyces cerevisiae, occurs when two haploid cells of opposite mating types signal using reciprocal pheromones and receptors, grow towards each other, and fuse to form a single diploid cell. To fuse, both cells dissolve their cell walls at the point of contact. This event must be carefully controlled because the osmotic pressure differential between the cytoplasm and extracellular environment causes cells with unprotected plasma membranes to lyse. If the cell wall-degrading enzymes diffuse through the cell wall, their concentration would rise when two cells touched each other, such as when two pheromone-stimulated cells adhere to each other via mating agglutinins. At the surfaces that touch, the enzymes must diffuse laterally through the wall before they can escape into the medium, increasing the time the enzymes spend in the cell wall, and thus raising their concentration at the point of attachment and restricting cell wall dissolution to points where cells touch each other. We tested this hypothesis by studying pheromone treated cells confined between two solid, impermeable surfaces. This confinement increases the frequency of pheromone-induced cell death, and this effect is diminished by reducing the osmotic pressure difference across the cell wall or by deleting putative cell wall glucanases and other genes necessary for efficient cell wall fusion. Our results support the model that pheromone-induced cell death is the result of a contact-driven increase in the local concentration of cell wall remodeling enzymes and suggest that this process plays an important role in regulating cell wall dissolution and fusion in mating cells.

QSAR in the study of mechanisms of biological activity of acetone in vitro

Using computer calculation of descriptors of the electronic structure of molecules of acetone and phytohormones—ethylene, indoleacetic acid (IAA), benzylaminopurine (BAP), naphthalene acetic acid (NAA), abscisic acid (ABA), and gibberellic acid (GA)—the similarity of the activity of acetone with that of a number of phytohormones was found. The results of computer simulation were tested in biological experiments. The acetone bioactivity in vitro is also manifested in the possibility of dissolution of the cell walls and release of endogenous phytohormones in the formation of CO2, which activates photosynthesis. An assumption is made about the integrated action of these mechanisms.

Changing the relation between micro- and mesoporosity in porous glasses: The effect of different factors

The relation between micro- and mesoporosity in the porous glasses produced by leaching of two-phase alkali borosilicate glasses was studied by use of advanced classical nitrogen equilibrium adsorption–desorption methods and new kinetic method of diffusion diagnostics with mass spectral recording. The effect of different factors, such as chemical composition, conditions of acid and alkaline treatments on the change of morphology and pore characteristics of the micro- and mesoporous substructures in the porous glasses was revealed. The porous glasses are characterized by the polymodal size distribution of mesopores (up to 4 modes) and micropores (up to 3 modes). The shape of mesopores is not purely cylindrical; there is a contribution of conical and interglobular pores. The micropore volume decreases with the decrease of the mesopore specific surface area and increasing the globule diameters of secondary silica. The micropores in the porous glasses are generally the regions of interglobular contacts in secondary silica with 1–2 times the diameter of N2 molecules. The introducing lead oxide allows obtaining the porous glasses with the highest specific surface area, maximum micropore volume, and minimum micropore diameter. The introduction of phosphorus and fluorine in the glass matrix allows producing the porous glasses with the minimal porosity, mesopore surface area, micropore volume and with the maximal size of mesopores. When increasing the leaching concentration of hydrochloric acid from 1 to 3M and acid leaching time from 3 to 9h, the mesopore specific surface area decreases and the mesopore diameters increase. The effect of alkali leads to the monomodal pore size distribution of mesopores, significant increase in the mesopore volume, and significant reduction in the micropore volume. At this, the new micropores due to the dissolution of channel walls do not create.

Mass transfer in dual pipe bends arranged in an S-configuration

The mass transfer in dual in-plane short radius bends arranged in an S-configuration was measured for different separation distances (L/D) between the two bends. Experiments were performed using a wall dissolution technique with gypsum test sections at a Schmidt number (Sc) of 1280 for L/D from 0 to 5 at a Reynolds number (Re) of 70,000. The maximum mass transfer was found to occur between the outlet of the first bend outer wall and the inlet of the second bend inner wall in all cases. The maximum mass transfer occurred for L/D=0 and was 3.2 times larger than the average mass transfer in a fully developed pipe flow under the same flow condition. The maximum mass transfer decreased as the separation distance between the two bends was increased. The effect of Re on the mass transfer enhancement for a separation distance of L/D=0 was examined for Re in the range 40,000–130,000. The peak mass transfer was found to scale as Re0.93 and was similar to that of the peak mass transfer in a single bend.

Calcareous Nannofossil Biostratigraphy of A, B, C, D Wells, Offshore Niger Delta, Nigeria

The calcareous nannofossil biostratigraphy of four deep water wells, A, B, C, D, offshore Niger delta has been studied in order to document their biostratigraphic distribution, establish biozonation and stratigraphic correlation. Ditch cutting samples were collected at 30 ft intervals. They were processed according to the standard calcareous nannofossil sample preparation technique. A total of forty-two nannofossil species were identified in the four wells. Most parts of the wells are characterized by abundant and diverse nannofossil assemblages which permitted the subdivision of the sections into zones. A total of five zones and two subzones were identified from this study based on diagnostic marker species and notable nannofossil events. The zones are Catinaster coalitus zone (NN8), Discoaster hamatus (NN9), Discoaster loeblichi which occupy the base of Discoaster berggrenii and the top of Discoaster bollii was used to identify the NN10 zone. The main marker for this zone which is Discoaster calcaris is missing in the study wells; this may be due to dissolution of the calcitic wall during sedimentation process. Other zones encountered in this study are Discoaster berggrenii subzone (NN11a), Discoaster quinqueramus subzone (NN11b), Amaurolithus tricorniculatus zone (NN12) and Ceratolithus rugosus zone (NN13). The age of the strata ranges from the middle Miocene to the early Pliocene. The zones were based on the first and last appearances of maker species as well as their relative abundances. The occurrence of Amaurolithus delicatus in wells C and B implies that the well intervals containing the species cannot be younger than early Pliocene age. The four wells show good correlation with each other based on the identified zones. The biozones identified in this study will be useful for subdivision and correlation work in the deep offshore Niger delta Neogene sequence.

Cell wall dissolution of feeding cells in feeding sockets caused by Meloidogyne kikuyensis

Cell wall dissolution of feeding cells in feeding sockets caused by Meloidogyne kikuyensis

IDA: a peptide ligand regulating cell separation processes in Arabidopsis

In contrast to animals, plants continuously produce new organs, such as leaves, flowers, and lateral roots (LRs), and may shed organs that have served their purpose. In the model plant Arabidopsis thaliana the peptide INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) signals through the leucine-rich repeat-receptor-like kinases (LRR-RLKs) HAESA (HAE), and HAESA-LIKE2 (HSL2) to control the abscission of floral organs after pollination. Recent work from other plant species indicates that this signalling system is conserved and could regulate leaf abscission in soybean and tomato. Abscission is a cell separation process involving the breakdown of cell walls between adjacent files of abscission zone (AZ) cells at the base of organs to be shed. The emergence of new lateral root primordia (LRP), initiated deep inside the root under the influence of the phytohormone auxin, is similarly dependent on cell wall dissolution to separate cells in the overlying tissues. It has been shown that this process also requires IDA, HAE, and HSL2. The receptors are redundant in function during floral organ abscission, but during lateral root emergence (LRE) they are differentially involved in regulating cell wall remodelling (CWR) genes. An overview is given here of the similarities and differences of IDA signalling during floral organ abscission and LRE.

How hexagonal mesoporous silica evolves in water on short and long term: Role of pore size and silica wall porosity

In this study, we have determined the evolution of the morphology and the structure of mesoporous silica MCM41 and SBA15 in saturation condition during short and long term alteration by water at 60°C. These materials were characterized using in situ/ex situ Small Angle X-ray Scattering (SAXS), and ex-situ by nitrogen adsorption–desorption and 29Si Nuclear Magnetic Resonance (NMR). The results have shown that MCM41 lost its hexagonal order of pores. This phenomenon has been attributed to a change of the pore shape probably due to the dissolution of silica wall and to the recondensation of hydrolysed silica on the pore surface leading also to a partial pore clogging at high alteration progress. In the case of SBA15, as soon as the porous silica is in contact with water, an altered silica layer is formed at the pore surface and dissolved at a rate of 120nmyear−1 leading to a pore size increase. When an equilibrium between dissolution and recondensation of the silica is reached, the silica dissolution rate strongly decreases (7nmyear−1) and the altered layer growth follows a diffusive process with a diffusion coefficient of D=1.4×10−24m2s−1. The differences of evolution between the two silica are explained by their different pore diameter and the presence of microporosity in the case of SBA15.

Anatomical changes induced by ethylene in the abscission zone of citrus leaf and fruit explants

ABSTRACT Abscission zones of leaves (LA-AZs) and 2-week-old fruits (AZ-A) of Citrus sinensis (L.) Osbeck cv. ‘Shamouti’ have similar structural and physiological characteristics. In both, the separation process involved the following events: cell walls swelled and became gelatinous, wall components degraded, and complete wall dissolution resulted in cell separation. The process was induced by ethylene and the reaction of the cell wall was pronounced. There were minor differences between the AZs of leaves and fruits. Abscission of the leaf at the LA-AZ began at the edge of the groove and proceeded inwards, whereas in the AZ-A of young fruits it first occurred in the middle and inner cortex and then advanced into the vascular tissues and outwards to the outer cortex. Six to eight-week-old fruits did not abscise at the peduncle AZ-A when treated either with ethylene or air. However, the marked anatomical changes that took place after ethylene treatment in the bark, pith, and vascular cylinder parenchyma cell...

Floral organ abscission peptide IDA and its HAE/HSL2 receptors control cell separation during lateral root emergence

Throughout their life cycle, plants produce new organs, such as leaves, flowers, and lateral roots. Organs that have served their purpose may be shed after breakdown of primary cell walls between adjacent cell files at the site of detachment. In Arabidopsis, floral organs abscise after pollination, and this cell separation event is controlled by the peptide INFLORESCENCE DEFICIENT IN ABSCISSION (IDA), which signals through the leucine-rich repeat receptor-like kinases HAESA (HAE) and HAESA-LIKE2 (HSL2). Emergence of new lateral root primordia, initiated deep inside the root under the influence of auxin, is similarly dependent on cell wall dissolution between cells in the overlaying endodermal, cortical, and epidermal tissues. Here we show that this process requires IDA, HAE, and HSL2. Mutation in these genes constrains the passage of the growing lateral root primordia through the overlaying layers, resulting in altered shapes of the lateral root primordia and of the overlaying cells. The HAE and HSL2 receptors are redundant in function during floral organ abscission, but during lateral root emergence they are differentially involved in regulating cell wall remodeling genes. In the root, IDA is strongly auxin-inducible and dependent on key regulators of lateral root emergence--the auxin influx carrier LIKE AUX1-3 and AUXIN RESPONSE FACTOR7. The expression levels of the receptor genes are only transiently induced by auxin, suggesting they are limiting factors for cell separation. We conclude that elements of the same cell separation signaling module have been adapted to function in different developmental programs.

Microsporogenesis and exine structure in Trochodendron aralioides Siebold and Zuccarini (Trochodendraceae)

This study aimed to elucidate the anther wall development, pollen wall development, and exine structure of Trochodendron aralioides Siebold and Zuccarini, a tree with primitive vessels but long considered to lack vessel elements in its wood. The anther wall is the basic type: epidermis, endothecium layer, three middle layers, and tapetum. The anther tapetum is glandular and cells are uniseriate. Microspore mother cells undergo meiosis with simultaneous cytokinesis to produce tetrahedral tetrads enclosed within a callose wall. Before development of the protectum, primexine is inserted against the callose, and the plasma membrane is invaginated. Then, the probacula are elongated under the protectum and arise basally from the plasma membrane. The foot layer formation is concomitant with callose wall dissolution. The foot layer is thick, and the endexine is thin. The foot layer and the endexine are both continuous. The intine is initially formed in the vacuolated microspore stage. Hollow Ubisch bodies are observed on the inner surface of the tapetum in free microspore stage. Pollen grains are tricolporate and 2-celled at the time of shedding. The numerous anthers of a single flower are at different development stages in both protandrous and protogynous individuals.

Dolomite-rich coralline algae in reefs resist dissolution in acidified conditions

Wave-resistant algal rims—chiefly composed of carbonate from crustose coralline algae—form critical structures for the survival of many shallow coral reefs, raising concerns about the susceptibility of these protective structures to ocean acidification. Research now shows that dolomite-rich frameworks—common in shallow coral reefs globally—are likely to persist as carbon dioxide increases. Coral reef ecosystems develop best in high-flow environments but their fragile frameworks are also vulnerable to high wave energy. Wave-resistant algal rims, predominantly made up of the crustose coralline algae (CCA) Porolithon onkodes and P. pachydermum1,2, are therefore critical structural elements for the survival of many shallow coral reefs. Concerns are growing about the susceptibility of CCA to ocean acidification because CCA Mg-calcite skeletons are more susceptible to dissolution under low pH conditions than coral aragonite skeletons3. However, the recent discovery4 of dolomite (Mg0.5Ca0.5(CO3)), a stable carbonate5, in P. onkodes cells necessitates a reappraisal of the impacts of ocean acidification on these CCA. Here we show, using a dissolution experiment, that dried dolomite-rich CCA have 6–10 times lower rates of dissolution than predominantly Mg-calcite CCA in both high-CO2 (∼ 700 ppm) and control (∼ 380 ppm) environments, respectively. We reveal this stabilizing mechanism to be a combination of reduced porosity due to dolomite infilling and selective dissolution of other carbonate minerals. Physical break-up proceeds by dissolution of Mg-calcite walls until the dolomitized cell eventually drops out intact. Dolomite-rich CCA frameworks are common in shallow coral reefs globally and our results suggest that it is likely that they will continue to provide protection and stability for coral reef frameworks as CO2 rises.

Dissolution of Weak Acids Under Laminar Flow and Rotating Disk Hydrodynamic Conditions: Application of a Comprehensive Convection–Diffusion–Migration–Reaction Transport Model

A steady-state mass transfer model that incorporates convection, diffusion, ionic migration, and ionization reaction processes was extended to describe the dissolution of weak acids under laminar flow and a rotating disk hydrodynamics. The model accurately predicted the experimental dissolution rates of benzoic acid, 2-naphthoic acid, and naproxen in unbuffered and monoprotic buffers within the physiological pH range for both hydrodynamic systems. Simulations at various flow rates indicated a cube root dependency of dissolution rate on the flow rate for a given bulk pH value for the laminar hydrodynamic system, as proposed earlier by Shah and Nelson (1975. J Pharm Sci 64(9):1518-1520) for neutral compounds. The model has limitations in its ability to accurately predict the dissolution of weak acids under certain conditions that imposed steep concentration gradients, such as high pH values, and for polyprotic buffer systems that caused the numerical solution to be unstable, suggesting that alternative numerical techniques may be required to obtain a stable numerical solution at all conditions. The model presents many advantages, most notably the ability to successfully predict the complex process under physiological conditions without simplifying assumptions, and therefore accurately representing the system in a comprehensive manner.

Pore formation in p-type silicon in solutions containing different types of alcohol

Macroporous structure of silicon can be obtained with anodization in hydrogen fluoride (HF) solution. The macropore formation in the presence of alcohol was studied. Macroporous layer formation in a low-concentration HF solution is stabilized with the increasing number of carbon in alcohol. The dissolution at the topmost part of the porous layer is observed though the behavior depends upon the type of alcohol. Meanwhile, the total mass loss of dissolved silicon is almost constant. Such dissolution at the top surface occurs only when the concentration of HF is low. Adding organic solvents to the HF solution also leads to the suppression of the pore wall dissolution. The type of alcohol and HF concentration in solution affect the formation of porous silicon.

DISSOLUTION OF HOLOCELLULOSE IN IONIC LIQUID ASSISTED WITH BALL-MILLING PRETREATMENT AND ULTRASOUND IRRADIATION

One of the most promising technologies for lignocellulosic biomass utilization employs ionic liquids for the conversion of isolated components into fuels, pharmaceuticals, chemicals, and composites after fractionation of lignocellulose. However, the time required for dissolution of the whole cell wall has been excessive. To explore a possible dissolution and fractionation pathway of lignocelluloses, the dissolution of holocellulose isolated from bagasse was investigated in 1-butyl-3-methylimidazolium chloride ([C4mim]Cl) assisted with ball-milling pretreatment and ultrasound irradiation. Ball milling pretreatment, ultrasonic irradiation assistance, and their combination were found to effectively improve the holocellulose dissolution in [C4mim]Cl. The effects of ultrasound power and irradiation duration on the dissolution time of ball-milled holocelluloses in [C4mim]Cl were studied. The regenerated holocelluloses were characterized with FT-IR, X-Ray, and CP/MAS 13C-NMR. It was found that there were no obvious changes of chemical structure after dissolution and regeneration of the holocellulose. The crystalline structure of cellulose was converted from cellulose I in native holocellulose to cellulose II in the regenerated holocellulose. The crystallinity decreased after the process of dissolution and regeneration assisted by ball-milling pretreatment and ultrasound irradiation.

Identification of Grass-specific Enzyme That Acylates Monolignols with p-Coumarate

Lignin is a major component of plant cell walls that is essential to their function. However, the strong bonds that bind the various subunits of lignin, and its cross-linking with other plant cell wall polymers, make it one of the most important factors in the recalcitrance of plant cell walls against polysaccharide utilization. Plants make lignin from a variety of monolignols including p-coumaryl, coniferyl, and sinapyl alcohols to produce the three primary lignin units: p-hydroxyphenyl, guaiacyl, and syringyl, respectively, when incorporated into the lignin polymer. In grasses, these monolignols can be enzymatically preacylated by p-coumarates prior to their incorporation into lignin, and these monolignol conjugates can also be "monomer" precursors of lignin. Although monolignol p-coumarate-derived units may comprise up to 40% of the lignin in some grass tissues, the p-coumarate moiety from such conjugates does not enter into the radical coupling (polymerization) reactions of lignification. With a greater understanding of monolignol p-coumarate conjugates, grass lignins could be engineered to contain fewer pendent p-coumarate groups and more monolignol conjugates that improve lignin cleavage. We have cloned and expressed an enzyme from rice that has p-coumarate monolignol transferase activity and determined its kinetic parameters.

Histopathology of Bt Cotton Roots Infectedwith Rotylenchulus reniformis

Histopathological studies on Rotylenchulus reniformis infected three Bt hybrids viz., Bunny Bt, Rasi Bt, and Jagannath fusion Bt in comparison with their respective non Bt (Refugia) were carried out. R. reniformis caused heavy damage to cortical, endodermis, pericycle, phloem cells in addition to extensive hypertrophy, dissolution and breakdown of cell wall in non Bt cotton. Whereas in Bt the cell damage caused due to was not severe compared to non Bt cotton. The compact arrangement of cortical and phloem cells and reduced area of phloem vessels in Bt cotton might have reduced severity of R. reniformis damage in Bt cotton.

In-depth study of self-ordered porous alumina in the 140–400 nm pore diameter range

The growth of self-ordered anodic aluminum oxide (AAO) templates with pore diameters in the 140–400 nm range is achieved by anodization in phosphoric acid at low temperatures (−4 °C). The procedure used in this study is able to completely avoid the “burning” of the oxide, highly frequent in anodizations in phosphoric acid solutions at high voltages. The current density measured during the anodizations is rather low, 0.6–0.7 mA/cm 2; therefore, low growth rates have been also measured (<2 μm/h). AAO templates present a relatively low porosity value of 8.4%. However, a considerable pore-enlargement-rate ( v Δ d = 0.636 ± 0.101 nm/h) has been observed as a consequence of the chemical dissolution of the pore walls during the anodization. Thus, the results reported here constitute an exhaustive study on the preparation of large-diameter-pore self-ordered AAO templates that enables both to access to pore diameters up to now inaccessible and to efficiently overcome the difficulties of their fabrication process ascribed to its aggressive reaction conditions.