Action Of Water Vapor Research Articles

Piezoactive Bioorganic Diphenylalanine Films: Mechanism of Phase Formation.

Self-organized peptides are unique materials with various applications in biology, medicine, and nanotechnology. Many of these applications require fabrication of homogeneous thin films having high piezoelectric effect and sufficiently low roughness. Recently, a facile method for the controlled deposition of flat solid films of the most studied peptide, diphenylalanine (FF), has been proposed, which is based on the crystallization of FF in the amorphous phase under the action of water vapor. This method is very advantageous compared with crystallization from a liquid phase reported previously. Here, we thoroughly investigate the mechanism of solid-state transformation from the amorphous to crystalline phase. The study revealed that the process proceeds in two distinct stages, maintaining clamped condition of self-assembling building blocks that preserve the films' morphology and high piezoelectric activity. We emphasize the critical role of water diffusion that governs two-dimensional growth of crystalline domains in FF films, merging in very dense, flat, and homogeneous films. These findings open a wide perspective for using this methodology for the direct fabrication of biofilms from the amorphous phase. We thus expect the application of these films to various nanotechnological applications of self-assembled structures.

52.3: Mechanism of Perforated Encapsulation Failure in Reliability Test of Foldable Display

As flexible OLED technology continues to mature, new technologies such as folding screens and in-screen punching have been widely used in many fields such as mobile phones and portable laptops. Overlapping application of new technologies meets the needs of consumers and provides competitive products for the market, but also puts forward higher requirements for product reliability. In this research, the mechanism of dark spot caused by encapsulate failure in perforated area of foldable display screen in reliability test was systematically studied. Under the action of water vapor and electricity, the K element in the polarizer reacts electrochemically to generate KOH, which further generates K2SiO3 chemically with SiO2 of CVD encapsulation layer, resulting in the expansion of CVD film and encapsulation failure. Water vapor denatures the organic luminescent materials, dark spots appear.

Features of the formation of the structure and properties of powder steels with additives that activate diffusion processes during sintering

Effect of activating the sintering process of powder steel alloyed with nickel or chromium by grinding the initial powders and introducing alkali metal compounds was investigated. The kinetics of grinding the initial iron powders, Cr30, and a mixture of iron powders with 4 % nickel was studied. It is shown that, depending on the hardness of the powder, it is grinded in three or two stages. When grinding more hard powders, there is no stage of intensive deformation of particles and an increase in their size. Crystalline lattice defects resulting from grinding of powders accelerate diffusion processes. This reduces sintering temperature by 100–200 °С compared to the sintering temperature of steels from the initial powders, contributes to a homogeneous structure, reduces porosity by 4–17 %, and increase strength of powder steels by 1.5–1.6 times. The mechanism of the effect of sodium bicarbonate on the acceleration of diffusion of carbon, nickel and chromium into iron has been established. With the introduction of sodium bicarbonate under the action of water vapor, formed upon its decomposition to carbonate, thin oxide films are formed on iron particles, which are actively recovered in a protective-recovering atmosphere during sintering. This leads to formation of a metal contact between the particles, acceleration of the self-diffusion of iron atoms and the diffusion of alloying additives into iron by 5–7 times, depending on the sintering temperature and the amount of added additive. Sodium forms nanodispersed complex compounds of the ferritic type Na3Fe5O9along the grain boundaries of the iron base, which provide grain refinement and the formation of a homogeneous structure. Changes in the structure of powder steel with the introduction of sodium bicarbonate cause an increase in its strength by 1.5–1.7 times. The results can be used to obtain structural products from alloyed powder steels.

Action of Water Vapor in the High-Temperature Hydrogenation of a Mixture of Coke-Plant Benzene and the Naphthalene Fraction of Coal Tar

Abstract—In the catalytic high-temperature hydrogenation (hydrodealkylation) of a mixture of raw coke-plant benzene and the 180–230°C naphthalene fraction of coal tar, water vapor (steam) acts in two ways: it blocks the smallest pores in the catalyst, from which the removal of products is difficult; and it facilitates their desorption from the large pores, thereby decreasing the likelihood of polymerization of the reactive products of intermediate hydrocracking and dealkylation. Steam is found to play a positive role in slowing the formation of high-molecular compounds, which are sources of coke deposits on the catalyst.

To the Question of the Production of Silicon Carbide

The issue of qualified use of the whole granulomeres composition of petroleum coke is considered. The possibility of using petrochemical fines for the production of silicon carbide is shown. Various technologies for upgrading petro-coke fines are presented and their advantages and disadvantages are revealed. An optimal variant of the preparation of petrochemical fines, in which the main driver for the production of silicon carbide is proposed. The possibility of a significant increase in the reactivity and specific surface area of oil reducing agents due to precision sifting by refined petrochemical fines and removal of excess moisture from petrochemical fines is shown. Due to the evaporation of moisture and the action of water vapor on the carbonaceous material, a positive effect can be created, consisting in the vapor activation of the reducing agent, accompanied by an increase in its reactivity and resistivity. It has been established that the increased humidity of the reducing agent degrades the heat balance of the electric smelting because of the heat costs for evaporation and, in part, the dissociation of water, and also causes an increased consumption of the reducing agent due to its active oxidation with water vapor and water dissociation products.

Investigation of Microstructural Humid Deformations in Epoxy Fiberglass at Heat-Humidity Corrosion Using Fiber-Optic Deformation sensors

In the present work, the possibility of using integrated fiber-optic deformation sensors (Bragg’s sensors) to control the state of the fiberglass on an epoxy anhydride hot cure binder is studied. Sensors are located in different layers of the layered plastic reinforced by a biaxial fiberglass cloth. A package has a quasi-isotropic structure. A sample is prepared by the method of vacuum impregnation and it is exposed to the action of water vapor with the relative humidity of 95% at 80°C. It is found that the moisture sorption in the composite occurs by a relaxation mechanism and is accompanied by a nonmonotonic change of swelling deformation in different layers of epoxy fiberglass. The swelling deformations in different layers of fiberglass are detected, their evolution during heat-humidity corrosion is shown, and, based on these data, the working capacity of the system of the measurements of the humid deformations of the fiberglass using for pipe production is confirmed.

Physically activated charcoal from waste and low-cost biomass: Adsorptive and porosity studies

ABSTRACTDifferent plant raw materials (corn stalk, wheat straw, saw dust, corn cobs, broom grass and Sudan grass) were carbonized and secondary activated in the rotating kiln with the action of water vapor as activation agent under different temperatures and lasting times. Optimum carbonization parameters such as temperature and lasting time were found to be 750°C and 45 min, while optimal conditions for powdered activated carbon obtained by water vapor activation at a temperature of 1,000 C and contact time of 120 min were determined. All obtained activated carbons were distinctly macroporous with mercury intrusion total specific pore volume in the range from 2.04 to 4.86 cm3/g for activated carbons originating from sawdust and broom grass, respectively. Activated carbon prepared from broom grass had the largest specific surface area of 1,190 m2/g. Freundlich, Langmuir, Dubinin-Radushkevitch and Temkin adsorption isotherm models were applied for groundwater humic matter adsorption modeling. Broom grass-originated activated carbon was found to have excellent adsorption affinities toward natural organic matter with regard to the Langmuir model, with maximum adsorption capacity of 90.1 mg TOC/g. The Freundlich isotherm was best fitted with the obtained experimental data. Adsorption experiment followed a physical process as can be seen from heat of sorption of 118.82 J/mol estimated by the Temkin isotherm model, and mean free energy of 0.158 kJ/mol estimated by the Dubinin-Radushkevitch isotherm model.

Control of Machining Process for Titanium Alloy Based on Green Cooling and Lubricating Technology

The machining process of titanium alloys always need special control by using coolant and lubricant as it is one of the difficult-to-cut materials. The cutting experiments are carried out based on green cooling and lubricating technology. To achieve green cutting of titanium alloy Ti-6Al-4V with water vapor cooling and lubricating, a minitype generator is developed. Compared to dry and wet cutting, the using of water vapor decreases the cutting force and the cutting temperature respectively; enhances the machined surface. And it can help to chip forming and breaking. Water vapor application also improves Ti-6Al-4V machinability. The excellent cooling and lubricating action of water vapor could be summarized that water molecule has polarity, small diameter and high speed, can be easily and rapidly to proceed adsorption in the cutting zone. The results indicate that the using of water vapor has the potential to attain the green cutting of titanium alloy.

Machining Process of Titanium Alloy Based on Green Cooling and Lubricating Technology

The machining process of titanium alloys always need special control by using coolant and lubricant as it is one of the difficult-to-cut materials. To achieve green cutting of titanium alloy Ti-6Al-4V with water vapor cooling and lubricating, a minitype generator is developed. Compared to dry and wet cutting, the using of water vapor decreases the cutting force and the cutting temperature respectively; enhances the machined surface appearance. Water vapor application also improves Ti-6Al-4V machinability. The excellent cooling and lubricating action of water vapor could be summarized that water molecule has polarity, small diameter and high speed, can be easily and rapidly to proceed adsorption in the cutting zone. The results indicate that the using of water vapor has the potential to attain the green cutting of titanium alloy instead of cutting floods.

Possibility of quantum chemical evaluation of the probability of various chemical transformations in syntheses of phosphorus-, titanium-, silicon-, and vanadium-containing structures on the silica surface

Application of minimum quantum-chemical models for predicting chemical transformations in syntheses of phosphorus-, titanium-, silicon-, and vanadium-containing structures on the silica gel surface by molecular layering is considered. Possible pathways for transformation of the groups synthesized under the action of water vapor and hydrogen chloride are analyzed in terms of the models constructed.

Hydrogen-induced phase transition in barium cerate

The action of water vapor on nominally pure BaCeO3 perovskite at 850 K causes hydrogen to be incorporated into the lattice and a thermally metastable state to form. The lattice symmetry changes as a result of an orthorhombic-pseudocubic transition which takes place at a temperature substantially lower than the known thermally initiated rhombohedral-cubic transition at 1173 K.

Influence of water vapour and oxygen co-adsorption on adhesion: self-adhesion of aluminium

Cold‐welding of contacting surfaces or self‐adhesion is frequently encountered in situations such as deep drawing or in rolling. The cleanliness of the surfaces is of paramount importance and small traces of impurity can alter the process significantly. In this article, the effect of oxygen and water vapour adsorption on self‐adhesion of aluminium has been studied in a tensile test. Clean surfaces are created by rupture, then they are contaminated in a controlled manner before testing in a tensile experiment. Dry oxygen has no affect on adhesion, but reinforces the deleterious action of water vapour. An analysis of the adsorption states of hydrogen and oxygen incorporated has been carried out and the results are compared with the existing data in the literature. It is concluded that the loss of adhesion results from the embrittlement of the interfacial region. Aluminium embrittlement is linked to the existence of hydroxyl radicals on the surface and the implications of these findings are discussed.

Organic Curing Agents for Polysulfide Sealants. II. Additions of Thiols to Nitrile Oxides: Scope, Relative Reactivities and Application to the Cure of Polysulfide Sealants

Efficient addition between various nitrile oxides and both short (C2) and long chain (C16) alkyl thiols , aliphatic dithiols and aryl thiols occurred rapidly at ambient temperature with the formation of thiohydroximic acid derivatives. Competitive experiments with bis( nitrile oxides) showed that for terephthalonitrile oxide the second addition proceeded more readily than the first whereas with anthracene-9,l0-bis(carbonitrile oxide) elevated temperatures were needed to obtain the diadduct. Relative reactivities of a number of thiols with nitrile oxides were also determined spectroscopically . Reaction between prop-2-ene-1-thiol and p-nitrobenzonitrile oxide afforded products resulting from both cycloaddition and 1,3-addition with the latter predominating. The polysulfide prepolymer LP-2 was cured effectively at ambient temperatures by both terephthalonitrile oxide and 4,4'-sulfonylbisbenzonitrile dioxide at CNO to SH ratios of 1.5 and higher giving tack-free products within 0.5 h and 90% cure in under 4 h. For the less highly cross-linked LP-32-based sealants, curing was a little slower. Unreinforced sealants produced in this manner were firm elastomers with hardness of 35-40 (Rex A). The naphthalenebis (carbonitrile oxides) afforded softer products while anthracene-9,10- bis(carbonitrile oxide) was ineffective. One-part formulations involving in situ generation of nitrile oxide from hydroximoyl chlorides and barium hydroxide (formed by action of water vapour on barium oxide) were also produced.

Introduction of water and water-containing solvent mixtures in capillary gas chromatography : III. Water-resistant deactivation of uncoated precolumns?

Uncoated capillaries, deactivated by silylation or by layers of non-extractable Carbowax or phenylsilicones, rapidly become active when water or (a far weaker effect) alcohols such as methanoi are introduced. Apparently, the effect is far more pronounced for condensed water than for water vapour, as analogous separation columns hardly suffer under the action of water vapour. The resulting high adsorptivity of the precolumns is hardly noticed as long as the sample matrix contains water by itself. A thin layer of OV-17, “baked” on to raw fused silica, produced the best, but still unsatisfactorily, water-resistant deactivation.

The influence of water vapour on the transformation of γ calcium sulphate anhydrite to β anhydrite

The isothermal kinetics of the transformation of γ calcium sulphate anhydrite to β anhydrite have been determined. All the curves obtained have a sigmoidal form. We have also observed an influence of the water vapour pressure on the rate of formation of β anhydrite. On each plot of rate vs. water vapour pressure one observes a maximum whose position shifts to lower values of water vapour pressure when the temperature decreases. The formation of β anhydrite a low temperatures may be explained by the geometry of the water vapour pressure-temperature diagram of the hydrated forms of calcium sulphate, and by the “mineralizing” action of water vapour at or close to saturation.

Chemical and microprobe investigations of the Allende-meteorite

Results of chemical and radiochemical bulk-analysis of main-, minor- and trace elements in the Allende meteorite are with the only exception of Hg in good agreement with respect to mean values characteristic for C III chondrites. Mineralogical and petrographical investigation shows three distinct components: chondrules and irregular white aggregates embedded in a fine grained black matrix. Electron microprobe analyses were performed on silicate, metal, sulfide and oxide grains. The chondrules consist mainly of Mg-rich olivine, furthermore of clinoenstatite, anorthite, Ca-Al-rich glass and minute amounts of metal and sulfide. A marked feature is the separation of metal into kamacite and taenite, the presence of awaruite- (∼ Ni3Fe) and of taenite-grains, which are surrounded of a goethitelike oxide. The white aggregates are a fine grained agglomeration of Ca-Al-rich minerals, e. g. spinel, augite, gehlenite, anorthite, and diopside. Informations about the composition of matrix were obtained by analysis using a defocused electron beam. The Allende meteorite belongs to the not- or only slightly equilibrated chondrites and has not been metamorphosed by action of shock or temperature during history. The white aggregates represent primary condensation products of the solar nebula. The conversion of troilite by the action of water vapor is suggested as a possible mechanism for the formation of the goethitelike mineral.

Studies on Organic Compounds containing Water or Solvent of Crystallization. X. Hydrate of Calcium 5-Ethyl-5-pentylbarbiturate.

In order to determine the amount of crystal water in calcium 5-ethyl-5-pentylbarbiturate, examinations were made on the action of water vapor on the hydrate and the anhydrate by the use of a quartz spring balance and a mercury manometer which may be able to estimate the reaction amount and equilibrium pressure. The amount of crystal water obtained from the flat part of the desorption curves corresponds to dihydrate. The rate of dehydration was examined over the temperature range of 20°to 50°and the rate of dehydration may be expressed by the formula (1-α)1/8=1-<kt>/r, where k is the rate constant, the fraction dehydrated at time t is α, and r is the initial radius of particle. From the experimental data, it was estimated that the activation energy for dehydration reaction of the hydrate is 9.5 kcal. / mole.

Nucleation phenomena arising during the dehydration of solid hydrates

The lattice vacancies formed on the evaporation of water molecules from the surfaces of potassium chrome alum have little mobility within the crystal. Treatment of crystals of potassium and ammonium chrome alums and copper sulphate pentahydrate in hard vacuum produces a change in the surface which under the catalytic action of water vapour gives rise to nuclei of the solid products. Common alum does not show these phenomena. The anomalous activation energies of the interface reactions of hydrates are discussed.

Prof. Camille Matignon

ARTHME CAMILLE MATIGNON, president of the French Chemical Society, who died suddenly in Paris on March 18, was a leading figure in pure chemistry and a great exponent of chemical technology. Matignon was born at Saint Maurice-aux-Riches-Hommes, Yonne, on January 3, 1867, and entered the Ecole Normale, Paris, in 1886; three years later he became assistant to Berthelot at the College de France and commenced a long series of original contributions to our knowledge of thermochemistry. After spending five years at the University of Lille as lecturer and professor, he was appointed as a temporary professor at the College de France in 1902, a supplementary professor in 1903 and, on the death of Berthelot, became professor of inorganic chemistry in 1908, holding this post until his death. Matignon early concerned himself with the great problem of the fixation of atmospheric nitrogen and the synthetic production of ammonia; he studied the direct combination of many of the metals with nitrogen, showing that zinc dust always contains zinc nitride, and preparing the nitrides of a number of the rare earth metals. Certain of the nitrides, such as those of silicon and aluminium, were probably formed during the cooling of the earth and, by the action of water vapour, gave ammonia, the first form in which nitrogen became available for assimilation by plant life. Matignon maintained that the increased use of artificial nitrogenous fertilisers was essential to the development of French agriculture; he followed up the advocacy of this principle by working out methods for the economic production of phosphates and potassium salts for use as manures.

Adsorption of Air and Water Vapor on Rock-Salt Surfaces

With a method previously described the adsorption of air on rock-salt surfaces is measured as a function of temperature, and the temperature at which complete outgassing occurs is determined. An estimate of the thickness of the film is given, and also the approximate speed at which it forms. The effect of water vapor on the surface is observed, and it is shown that exposure to water vapor has no permanent effect on the surface as long as the partial pressure of the water vapor is kept below that of a saturated sodium chloride solution at the same temperature. This, however, is true only of cleavage surfaces; polished surfaces are less stable against the action of water vapor.