Apparent Thickness Research Articles

Physicochemical Characterization of Tropical Agro-Industrial By-Products as Substrate for Nursery Plant Growth

ABSTRACT In Mexico, peat moss is the most used substrate to produce plants in containers, an imported product with a high cost. In Chiapas, there are agro-industrial by-products with substrate potential that are inexpensive and easy to acquire. The objective of this research was to determine the physical-chemical components of various proportions of tropical agro-industrial by-products for the growth of forest plants in a nursery. Different proportions of coffee husk (Coffea sp.), oil palm fiber (Elaeis guineensis Jacq.), sawdust mixture of tropical species, coconut fiber (Cocos nucifera L.), sugarcane bagasse (Saccharum officinarum L.) and the commercial product based on peat moss were used. A completely randomized experimental design with seven treatments and four replicates was used. The physical and chemical properties differed significantly (p < .05) between the mixtures. The mixture with 70% to 80% of agro-industrial by-products in combination with 20%–30% of commercial mixture, presented a greater number of physical properties (apparent density, aeration porosity, water retention, granulometry and thickness index) and chemical properties (hydrogen potential, electrical conductivity, cation exchange capacity, organic matter, organic carbon, total nitrogen, and carbon/nitrogen ratio) desirable for the growth of plants in nursery.

Laser oscillation from a distributed feedback structure with a diffraction grating directly fabricated on an organic crystal surface using a focused ion beam and plasma etching

Laser oscillation was achieved through optical excitation of a distributed feedback (DFB) laser with a diffraction grating directly fabricated on the surface of an organic crystal using focused ion beam (FIB) processing and subsequent plasma etching. The apparent core thickness of the crystal, which served as the core layer containing the corrugated structure, was determined by analyzing the dependence of the diffraction peak on the measurement direction from the DFB structure. Measurements on multiple samples revealed that the apparent core thickness is proportional to the crystal thickness in the unprocessed and etched regions, excluding the regions of the corrugated structure. For a specific crystal, the unprocessed and etched area thickness was predicted from the preprocessed crystal thickness, and the apparent core thickness was calculated accordingly. Using this value, the effective refractive index of the DFB structure was estimated, and the optimal diffraction grating period was designed based on the maximum fluorescence wavelength of the crystal corresponding to the Bragg wavelength. A DFB laser device with this optimized grating period was fabricated via FIB processing and plasma etching. When optically excited with increasing pulse laser intensity, the device exhibited a nonlinear rise in emission intensity and a marked narrowing of the emission spectrum. These findings demonstrated that laser oscillation was successfully achieved using a diffraction grating directly fabricated on the organic crystal surface through FIB processing and plasma etching. This work underscores the potential of direct surface fabrication for the development of high-performance organic laser devices.

EFEITOS DA APLICAÇÃO DE NANOPRODUTO NAS PROPRIEDADES FÍSICAS DE PAINÉIS COMPENSADOS

This study aimed to evaluate the physical properties of plywood panels treated with a silica-based nanoproduct, aiming to analyze the performance of the material before and after natural aging. The tests were performed using plywood panels of Schizolobium parahyba var. amazonicum (Huber ex Ducke) Barneby (Paricá), divided into two groups: with and without application of the nanoproduct. The properties of apparent density, water absorption, thickness swelling and humidity were evaluated. The analysis of variance indicated no statistically significant difference between the treatments before and after 120 days of natural aging, except for humidity, which presented average values ​​of 12.0% in the untreated specimens and 10.1% in the treated ones. The treated panels presented lower moisture content, suggesting that the nanoproduct contributed to the reduction of porosity and, consequently, of water absorption. Despite this, the other physical parameters did not demonstrate significant improvements, possibly due to the concentration used. The results demonstrate the potential of the nanoproduct to increase the moisture resistance of the panels, although additional studies on the formulation and exposure time are necessary to maximize its performance.

Influence of care maintenance cycles on comfort-related parameters of clothing protecting against heat and flame

The life cycle of a product, such as protective clothing, includes a specific number of maintenance cycles, defined by the manufacturer. Beyond this number of washing cycles, the clothing can no longer be used, as its protective properties are no longer guaranteed after the stated limit is reached. This article presents the results of tests conducted to examine parameters related to the thermophysiological comfort of both finished products and the textile materials used in their production. These tests were conducted on items in their new condition (as supplied by the manufacturer) and after 50 maintenance cycles, which is the maximum number specified by the manufacturer. Additionally, the materials were tested after 5 and 25 maintenance cycles to assess intermediate changes. Experiments conducted on two types of material used in protective clothing for protection against heat have shown that both the area density and the number of maintenance cycles have a significant effect on parameters related to thermophysiological comfort. Additionally, changes in fiber morphology were visualized by scanning electron microscopy and measurements of the apparent length and thickness of weft yarns between successive warp coverings were made. The results of the analysis of individual material properties before and after successive washing cycles allowed us to identify key differences in the behavior of the two types of material used in protective clothing.

Enhancing Silica Scaling Resistance and Perm-Selectivity of Reverse Osmosis Membranes via Increased Charge Density and Suppressed Coordination Capacity.

Silica scaling poses a substantial challenge in the advanced treatment of industrial wastewater by reverse osmosis (RO) membranes, while the existing methods modifying RO membranes to enhance antisilica scaling performance often compromise water permeance. Herein, we fabricated a sulfonated RO membrane (SLRO) using sodium lignosulfonate as a comonomer, achieving an enhanced charge density and reduced coordination capacity. SLRO exhibited superior antisilica scaling performance, reducing scaling rates by ∼145, ∼166, and ∼157% under acidic, neutral, and alkaline conditions compared to the control. Reduced density gradient analysis confirmed that sulfonic acid groups (-SO3H) on the SLRO surface increased the repulsion of silicic acid. Moreover, the SLRO demonstrated reductions of ∼112, ∼137, and ∼133% in cation-mediated silica scaling rates under the same conditions, attributed to the weaker coordination between -SO3H and cations, which diminished the cation-bridging effect. Furthermore, SLRO membranes exhibited high pure water permeance (3.3 L m-2 h-1 bar-1) and NaCl rejection (99.2%), with a water/NaCl selectivity (7.8 bar-1) three times greater than that of the control (2.6 bar-1), primarily attributed to increased surface roughness and reduced apparent thickness of the PA layer. Our work provides a robust strategy for fabricating silica scaling-resistant RO membranes with improved perm-selectivity.

How 3D electron diffraction reveals all about crystal structure

Structure analysis using 3D electron diffraction (3D ED, aka ADT, cRED, MicroED) data has become increasingly popular among chemists and materials scientists for its ability to solve crystal structures from single nanocrystals. Despite substantial progress in this method, it is still generally considered to provide relatively low-accuracy structure models, unsuitable for all but basic crystallographic analysis. Recent advances in data acquisition, data processing in PETS2 [1], including determination of the exact experimental geometry, and dynamical refinement in Jana2020/Dyngo [2] with modeling of the apparent crystal thickness distribution, have enabled 3D ED to answer questions about the finest details of structure, including partially occupied hydrogen positions or charge density analysis. Figure 1 shows methyl disorder in acetaminophen and charge density analysis in L-tyrosine obtained from 3D ED data. It is also possible to determine the absolute structure [3]. For this purpose, the so-called z-score has been introduced for enantiopure materials [4]. However, if certain conditions are fulfilled, the classical Flack parameter determination can be applied in electron crystallography. These advances bring electron crystallography to the same level of accuracy as X-ray diffraction, with the ability to see light atoms alongside heavy ones due to a smaller increase in scattering potential with atomic number and greater sensitivity to the absolute structure of structures consisting of only light atoms.

Saturn’s G ring: insights from the dynamical evolution of dust particles from the G-ring arc

Abstract To explore the formation and properties of Saturn’s G ring, we study the dynamics of micron-sized dust particles originating from the arc of debris near the inner edge of the ring. The dynamical evolution of particles due to various perturbation forces and the plasma sputtering that erodes the particles is simulated by a well-tested numerical code. Based on the simulation results, the normal I/F of the G ring observed by the Cassini spacecraft can be explained by dust particles originating from the arc. Other properties of the G ring are also estimated, including the steady-state size distribution and the number density of ring particles, the geometric optical depth, the apparent edge-on thickness, the age and the remaining lifetime of the G ring. We find that the particle size distribution of the G ring follows a power law with an exponent of 2.8, and dust particles in the size range of $[5, 10]\, {\mu }$m are dominant within the ring. The average number density of particles of the G ring in the radial direction is about 10−3-10−2 m−3. The peak value of the edge-on geometric optical depth of the G ring is about 3.9 × 10−2. The maximum apparent edge-on thickness of the G ring with the geometric optical depth larger than 1 × 10−8 is approximately 9000 km. The age of the G ring is estimated to be 106-107 years, and the remaining lifetime of the ring is on the order of 104 years.

EFFICIENCY OF CARBON FIBER EXTRACTION BY LOW-TEMPERATURE SOLVOLYSIS

The paper presents the results of a comprehensive study of the effect of the structure of carbon fibers and the type of the initial polymer composite on the quality of the reclaimed fiber obtained by low-temperature solvolysis. The characteristics of the initial and reclaimed carbon fibers were analyzed using a wide range of experimental methods, including structural (X-ray diffraction analysis, scanning electron microscopy, Raman spectroscopy) and thermal studies. Solvolysis was carried out in a mixture of H2SO4 (conc.):H2O2 (conc.): H2O in a mass ratio of 2.5:3:1, respectively, at the boiling point of the solution. The recycling time was 1 h with a solution change every 20 min. The results of electron microscopy showed that, regardless of the type of polymer system, there are practically no binder residues on the surface of the fibers. Using thermal analysis, it was shown that the main mass loss of all samples of the reclaimed fiber occurs at temperatures above 600 ° C. Despite the fact that origin fibers with a smooth surface show greater thermal stability than those with a relief structure (mass loss temperature of 5% - 650°C and 620°C, respectively), extracted fibers based on the same brand have lower mass loss values. In order to assess the destructive effect of the solvolysis solution during extraction, the structural changes in the carbon fiber surface were studied by the method of Raman spectroscopy. The degree of graphitization was estimated by the ratio of the peak areas D (defective component) and G (graphite component). A decrease in the degree of graphitization after solvolysis was shown for both types of carbon fibers. The crystallite sizes of carbon fiber samples were determined by X-ray diffraction analysis. The results showed a decrease in the apparent thickness of Lc and the transverse size of the La crystallite for all samples after solvolysis. For citation: Trukhinov D.K., Lebedeva E.A., Ivanova E.V., Istomina T.S., Astaf’eva S.A. Efficiency of carbon fiber extraction by low-temperature solvolysis. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2025. V. 68. N 4. P. 59-66. DOI: 10.6060/ivkkt.20256804.7162.

Numerical simulation study on coal seam response characteristics of shallow three-electrode laterolog

Shallow three-electrode laterolog is widely used in the field of coal field logging because of its strong economy. Coal seams in Xinjiang region have the characteristics of large thickness variation, high dip angle, easy diameter enlargement and fracture development, but the law of these characteristics in the three-electrode laterolog curve is not clear. In this paper, through the finite element simulation software COMSOL Multiphysics, 2D and 3D models are constructed based on shallow three-electrode laterolog, and the characteristics of using shallow three-electrode laterolog in coal field logging are studied. The results show that the electrode system coefficient of shallow three-electrode laterolog instrument should be 0.94 times of the theoretical electrode system coefficient. The discrimination ability of shallow three-electrode laterolog to coal seams is about 0.3 m. There is a power function relationship between the determination coefficient of coal seam boundary and the ratio of coal seam-surrounding rock resistivity ratio. An increase in the dip angle of the coal seam leads to an increase in the apparent thickness of the coal seam following a quadratic function relationship, while an increase in the wellbore radius results in a quadratic function decrease in the apparent resistivity of the coal seam. An increase in both the width and length of the fractures leads to a decrease in apparent resistivity following a power function relationship. The research results provide a more accurate reference standard for the analysis and evaluation of coal seams using shallow three-electrode laterolog.

Getting Under the Sensor's Skin: The Importance of Electrical Contact Characterization for Conductive Composite Elastomers

Abstract Conductive elastomer composites can be used as flexible, lightweight, and inexpensive sensors, but they require ohmic electrical contacts to ensure readout consistency, and such contacts can suffer from hysteresis, non‐ohmic behavior, and cyclic fatigue. This work investigates a common cause of non‐ohmic conduction in such composite contacts, namely the thin insulating layer native to the surface of most silicone rubber composites that have been infused with multi‐walled carbon nanotubes for piezoresistive sensing. Voltage sweep dc measurements of individual contacts on this surface layer behave as parallel head‐to‐tail diodes with asymmetric hysteresis. Frequency sweep ac measurements quantify the insulator thickness with a leaky capacitor model to be ∼1 µm, independent of nanotube concentration, much thicker than the apparent layer thickness as imaged with scanning electron microscopy. This analysis also confirms highly anisotropic bulk conduction, circa 100 times higher in‐plane than cross‐plane. To remove the surface layer, a simple surface abrasion is shown to achieve deep ohmic electrical contact to the elastomer bulk. A three‐terminal method for verifying ohmic contacts is demonstrated and works even when all contacts are non‐ohmic. This three‐terminal method be easily applied to other conductive polymers for contact quality‐testing.

Vasilinovskoe platinum-palladium occurrence – a new type of mineralization in the ophiolites of the Polar Urals. Report 1. Geological position and mineralogy

A detailed description of the new noble metal (Pt-Au-Pd) Vasilinovskoe occurrence discovered near the Kharp town of the Yamalo–Nenets Autonomous Okrug is given. It is associated with amphibolized gabbroids and clinopyroxenites. Mineralization zones with an apparent thickness from 0.5 to 50 m (sulfides 1–3 vol.%, occasionally more) are developed in these rocks. In areas with scattered or finely nested sulfide inclusions, feldspar-quartz and epidote veinlets are often present. The first expedition to study the platinum-bearing area of the Rai-Iz mountains was organized by Professor A.N. Zavaritsky 100 years ago, in 1925 (A.G. Betekhtin was the head of the рrospecting party), but the expected placer platinum deposits were not found. Communication 1 includes general geological and detailed mineralogical characteristics of the ore occurrence and brief information on the bulk geochemistry of rocks and ores of the object. The mineralized gabbro-amphibolite ore macrocomponents, which are often found in bulk samples, can be noted (wt.%) V up to 0.2, Co up to 0.06 and Ni up to 0.02. According to assay data, in bulk 0.5–1 kg samples with sulfide inclusions, the Pd content reaches 1.4 g/t, Au – 0.8 g/t, and Pt – 0.2 g/t. The PGE minerals are represented by abundant impregnation of micron–sized palladium minerals: tellurides (merenskiite, temagamite, kotulskite, sopcheite), antimonides (stibiopalladinite, sadberite), arsenoantimonides (arsenic stibiopalladinite, isomertiite), as well as other noble metal compounds – moncheite, native osmium and others. In addition, the magnetite–chalcopyrite–pyrite assemblage contains microinclusions of native silver, bismuth and tin. In the later polysulfide–feldspar–carbonate–quartz assemblage, Au and Ag tellurides, native gold (including Hg-bearing), Se-containing argentite, and greenockite are found. In the zones of sulfide impregnation of the Podgornensky site (1.5 km to the south), occurring in the diorites of the Sob’ complex and closely associated with quartz veins, the amount of sulfides is higher, the copper profile is enhanced, and concentrations of Co, Ni, and especially Ti, V, Pd and Pt are falling. According to the LA-ICP-MS analyses of pyrite, chalcopyrite, pyrrhotite of the Vasilinovskoe occurrence, the profiling trace element for them is cobalt – up to 1.2 wt.% Co in pyrite of the early assemblage. The Ni impurity is also high (400-800 ppm, up to 0.2 wt.%) in the early pyrite and decreases to 16–90 ppm in the late pyrite. The impurity of Se, on the contrary, increases in pyrite of the late assemblage (up to 207 ppm). Chalcopyrite commonly contains As and Se (~100–300 ppm). In contrast to the Vasilinovskoe occurrence, at the Podgornensky site, an admixture of Mo (up to microinclusions of molybdenum), Te (up to 35 ppm), noticeable impurities Tl (up to 25 ppm) and Re (0.3 ppm) are present in pyrite. Impurities are often found in chalcopyrite: Ag up to 65 ppm, Sn up to 65 ppm, Cd up to 35 ppm and Bi up to 11 ppm. Significant impurities of Co and Ni (up to 0.n wt%) are typical here only for minor pyrrhotite. According to the mineral composition and geochemical spectrum of Pt-Au-Pd-Co ±Ni-Cu-V-Ti, the low-sulfide platinoid mineralization of the Vasilinovskoe occurrence contrasts quite strongly with the zones of low-sulfide mineralization (+chalcedony quartz) with the specialization Fe-Cu-Au-Ag (±W, Bi, Sn, Mo, Re) of the Podgornensky site, which probably belong to the skarn-porphyry gold-bearing system. The conclusion is made about the prospects of expanding the contours of Pd mineralization to the west and east, where the halos of Cu, Co and Ni, as well as magnetic anomalies, occur in the rocks of the basite-ultrabasite association.

Integration of slingram (geonics em34-3) and Schlumberger configuration for groundwater exploration and development of Ayegunle-Oka, southwestern Nigeria

The exploration and development of groundwater in the Precambrian Basement Complex of Ayegunle / Oka Akoko was necessitated because of perennial scarcity of potable water for communal purposes. The study was aimed at delineating the prolific aquiferous zones by the use of electromagnetic and Schlumberger- Vertical Electrical Sounding (VES) methods. Twenty (20) electromagnetic (EM) and electrical resistivity traverses of 100m long were carried out using Geonics co-planar loop system and ABEM SAS1000 Terameter. The EM and VES data were plotted against station position inverted and analyzed in terms of the conductivity and geo-electric parameter (apparent resistivity, depth and thickness) distribution in the area. The EM and VES dataset was processed using Karous-Hjelt and WinResist softwares. The interpretation of the electromagnetic profiles revealed some conductive zones that were prioritized for depth sounding. The result showed crossover point that diagnostic of conductivity. The apparent resistivity, depth and thickness of the subsurface strata ranges from: 81-1299 Ωm, 0.5-105.1m and 0.5-76.9m respectively. The lithologic strata vary from topsoil, clay/sandy clay, weathered/partially weathered, fractured/basement bedrock. The hydro-geologic cross-sections were categorized into: high, midrange, and low groundwater potential. The geophysical survey data revealed that the study region has the potential to play a key role in delivering adequate drinkable water for rural residents.

Melting Behavior and Ionic Conduction of Multicomponent Carbonates Coexisting with Porous Oxides

Multicomponent systems of alkali carbonates indicate high electrical conductivity, high chemical and thermal conductivity, and low viscosity in the medium temperature range around 500°C, and are used as high temperature reaction media, thermocouples, and sensing materials for CO However, in electrochemical reactions, the high reactivity of carbonates is accompanied by the problem of corrosion of electrodes and reaction systems. We have studied ceria-based oxides and zirconia, which have high reactivity through surface treatment of CO2 absorbing media, and have examined the electrical and thermal properties of the composite materials with molten carbonate. Ceria-based oxides have been considered for application in solid oxide fuel cells as solid electrolytes, whereas γ-LiAlO2 has insulating properties and is used as an electrolyte in molten carbonate fuel cells. In this study, lithium carbonate, sodium carbonate, and potassium carbonate are used as the liquid phase, and mono-, binary-, and ternary complex carbonates or carbonates with eutectic compositions are used. The results are summarized on the effect of salt complexation on the improvement of electrical conductivity at low temperature ranges and the lowering of melting points.The solid phase was obtained by drying three types of γ-LiAlO2 (24.0 m2/g, 10.3 m2/g, 5.4 m2/g) and other various oxides such as α-Al2O3, MgO, ZrO2 etc. at 500°C for 2 hours under nitrogen. Li2CO3, Na2CO3, and K2CO3 were used for the carbonate phase and dried at 200°C for 48 hours under a carbon dioxide atmosphere. Eutectic carbonates were prepared by mixing them to form a eutectic composition. Each oxide powder was mixed thoroughly in a mortar to form carbonate at a given volume ratio. The sample was formed by pressurization and sintered at 500°C for 1 hour to obtain a tablet for the measurements of ionic conduction and thermal analysis.As shown in Figure 1, the activation energy of electrical conductivity increased near the solid phase in all cases. The range of influence from the solid phase decreased significantly with increasing carbonate polymorphism: 40 nm for the mono-salt system, 10 nm for the binary system, and about 2 nm for the ternary system. These melting point drops are also affected by the solid phase, but the effect of the distance from the solid phase is not so great. In the vicinity of the solid phase, the effect of the solid phase on ionic conduction is not as strong as that on the phase change, and the more numerous ions move, the less affected by the solid phase the system is. In this presentation, we will discuss the influence of the solid phase from a viewpoint of thermodynamics.Fig.1 Variation of ΔE a with apparent average thickness for various carbonates /inorganic powders coexisting systems. Carbonates: (a)Li2CO3, (b) (Li0.52Na0.48)2CO3, and (c) (Li0.435Na0.315K0.25)2CO3. Figure 1

Two-dimensional P1 approximation (P1-2D) for the Description of the Radiant Field on Cylindrical Solar Photocatalytic Reactors

The local volumetric rate of photon absorption (LVRPA) was formulated by solving the radiative transfer equation (RTE) in polar coordinates with the P1 approximation approach (P1-2D) for the description of the radiant field in cylindrical solar photocatalytic reactors. A general expression of the LVRPA was formulated that can be employed on cylindrical photocatalytic reactors with an incident radiation constant along the reactor length. CPC and tubular photocatalytic reactors were used as reactor models and Lambert's cosine law (irradiance) was considered when using the boundary conditions. Simulations were carried out using the commercial TiO2-P25, its optical properties taken from the literature. The LVRPA was found to decrease exponentially from the reactor wall to its center. literature rate of photon absorption per unit of reactor length (VRPA/H) increased exponentially with the catalyst loading until a value where no significant increase was observed and was found to increase with reactor radius, information that agrees with the literature. The optimum catalyst loading with the CPC reactor was about 0.364 g/L with a reactor radius equal to 1.65 cm similar to that found in the literature when using the six-flux model in two dimensions (SFM-2D). The apparent optical thickness τ_App1 newly formulated with the P1 approximation was introduced for optimization purposes and was found more reliable than the optical thickness τ. This parameter not only removes the dependence of the optimum catalyst loading on the reactor's radius but also its dependence on catalyst albedo. τ_App1 was found about 9.73 and 14.6 for CPC and tubular reactors respectively and provides the optimum catalyst loading and the reactor radius that optimize the radiation absorption inside both reactors.

Regional variations in hyperpolarized 129Xe lung MRI: Insights from CSI-CSSR and CSSR in healthy and irradiated rat models.

To compare pulmonary function metrics obtained with hyperpolarized xenon-129 (HXe) MRS, using chemical shift saturation recovery (CSSR) and CSI-CSSR, in healthy rats and a rat model of radiation-induced lung injury. HXe-MR data were acquired in two healthy rats and one rat with radiation-induced lung injury using whole-lung spectroscopy and CSI-CSSR techniques. The CSI-CSSR acquisitions were performed with both fixed TE and variable TE. Apparent alveolar septal wall thickness, gas transfer dynamics, and regional lung function were quantified and compared across acquisition methods. Spectral analysis included alignment of dissolved-phase frequency spectra using the membrane resonance as reference, segmentation of gas-phase (GP) frequency distribution, and characterization of gas uptake in the vasculature. Complex GP line shapes were observed in rat lungs, necessitating pixel-wise CSI analysis and membrane resonance alignment for improved quantification. Notable differences in alveolar septal wall thickness, dissolved-phase GP ratios, and GP and red blood cell frequencies were found between acquisition techniques and lung conditions. CSI-CSSR provided unique insights into regional lung function, including the identification of distinct GP frequency zones potentially corresponding to different airway structures, and the ability to map relative xenon gas transport. Metrics from fixed-TE and variable-TE acquisitions usually differed by less than 10%, but the latter yielded a 20% SNR gain. HXe-MRS and CSI-CSSR techniques provide similar but not universally interchangeable insights into lung function, particularly in the presence of pathology.

Sustainable Panels from Cocoa (Theobroma cacao) Wood Wastes Bonded with Cassava starch and Urea–Formaldehyde

The demand for innovative products from renewable sources has motivated research development to create new sustainable materials. Cassava starch (CS) has been widely used for bonding and composing different types of products. Particleboards produced from cocoa (Theobroma cacao), wood wastes, and CS adhesives can be an environmentally correct and economically profitable alternative to replacing traditional commercial panels. This study aimed to manufacture particleboards made with wood waste extracted from the stem of Theobroma cacao. The panels were bonded with different proportions of CS and urea–formaldehyde (UF) adhesives, and their physical–mechanical properties were determined. To manufacture the panels, cocoa wood wastes were mixed with the adhesive in ratios of 90:10, 70:30, and 50%:50% (CS/UF). Two control treatments were bonded with 100% of both adhesives. The resulting particleboards were employed as a reference to compare properties. The manufacturing process was carried out by cold pressing. Apparent density, water absorption, thickness swelling, and static bending strength were found for all panels. The data obtained were subjected to Levene’s homogeneity test, Shapiro–Wilk’s normality test, analysis of variance (ANOVA), and Tukey’s mean test. The results showed that the highest density value was 497.0 kg m−3, corresponding to the treatment composed of cocoa wood wastes bonded with 100% CS adhesive. The water absorption and thickness swelling results after a 24 h immersion showed that the panel formed using cocoa wood wastes and 100% UF had the lowest values, 22.1 and 11.2%. The highest bending strength value was 13.1 MPa for the experimental treatment composed of cocoa wood residue and 100% UF. However, this result did not differ statistically from the treatment (50–50). Therefore, cocoa wood waste combined with adhesive CS may be a sustainable alternative for producing particleboards.

Two-dimensional P1 approximation (P1-2D) for the evaluation of the radiant field in annular and tubular photocatalytic reactors

The local volumetric rate of photon absorption (LVRPA) was formulated by solving the radiative transfer equation (RTE) in two dimensions using the P1 approximation approach (P1-2D) to describe the radiant field in annular and tubular photocatalytic reactors. The radiant sources employed were assumed to be periodic when applying the boundary conditions to facilitate the determination of the integration constants in the RTE solution. Three different systems were considered: S1 and S2 consisted of annular reactors, while S3 consisted of a tubular reactor. Simulations were conducted using commercial TiO2 P25 and anatase TiO2 as photocatalyst models, with their optical properties sourced from the literature. The linear source spherical emission (LSSE), Gaussian emission (GE), and uniform emission (UE) models were used as radiant sources. The LVRPA was found to decrease from the inner to the outer wall of the reactor for S1 and S2, and from the wall to the center of the reactor for S3; it was close to the values obtained using the Monte Carlo (MC) procedure in S2. The overall volumetric rate of photon absorption (OVRPA) increased exponentially with catalyst loading until a point where no significant increase was observed for each reactor. The apparent optical thickness τ App 1 ​formulated was a more reliable optimization parameter than the optical thickness.

Estimation and Optimization of the Radiant Field in Flat Plate Heterogeneous Photoreactors with the P1-approximation of the Radiative Transfer Equation (RTE).

In this work, the P1-approximation of the radiative transfer equation (RTE) was used for the description and optimization of the radiant field in a flat plate photoreactor under solar radiation with three commercial brands of titanium dioxide photocatalysts. The boundary layer of photon absorption (δ_abs), the average volumetric rate of photon absorption (VRPA), and a new apparent optical thickness (ζ_app1) were used as design parameters for optimization. A simple mathematical expression for the calculation of δ_abs also called the best reactor thickness was formulated. For the three catalysts, varying the reactor height (L), it was found a decrease in the local volumetric rate of photon absorption (LVRPA) from the top side until the bottom of the reactor for any value of the catalyst loading (Ccat). It was also observed that when Ccat increases the VRPA increases exponentially until a fixed value where it remains almost constant. With L= 1 cm, the optimum Ccat (Ccatop) was 0.2 g/l in 0.85 cm of thickness, 0.3 g/l in 0.82 cm of thickness, and 0.4 g/l in 0.89 cm of thickness for the photocatalysts Degussa P-25, Aldrich, and Hombitak respectively. The optimum apparent optical thickness (ζ_(app1,op)) was 4.03, 4.62, and 3.7 for the photocatalysts Degussa P-25, Aldrich, and Hombitak respectively. These results are in good agreement with the literature. Results found in this work give predictions on radiation absorption in flat plate photocatalytic reactors with different heights.

PRODUCTION OF MDP PANELS WITH YERBA MATE HARVEST RESIDUES

The quality of MDP panels produced with Pinus taeda wood particles mixed with yerba mate harvest residues was evaluated. Monolayer panels were produced with the addition of 0. 20. 40. 60. 80 and 100% proportion of yerba mate waste, with a nominal specific gravity of 0.65 g.cm-³, using 12% urea-formaldehyde resin, 0.5% paraffin and 2% ammonium sulfate catalyst. The panels were pressed for 10 minutes at a temperature of 140°C and pressure of 40 kgf/cm². The physical properties of apparent density, moisture content, water absorption and thickness swelling (2 and 24 hours) were evaluated, as well as the mechanical properties of static bending (MOR and MOE), internal bonding, screw withdrawal on the face and Janka hardness. There was a trend towards an increase in internal bonding with an increase in the proportion of yerba mate residue in the panels, but the opposite occurred for the other mechanical properties studied. Some physical properties such as water absorption and thickness swelling resulted in better performance when yerba mate particles were added. In view of this, it can be concluded that it is possible to produce panels with the addition of yerba mate up to 40% in the composition with yerba mate particles, without affecting the quality of the properties.

Influence of Surface Roughness on Phosphonation and Wettability of Nanosecond Laser‐Treated Titanium Surfaces

The duplex treatments of metal surfaces combining laser‐assisted functionalization and chemical modification attract a growing interest in view of better control of functional properties such as wettability. Patterned titanium oxides layers of different nature and roughness are produced in ambient atmosphere on a titanium surface using a nanosecond 532 nm Nd:YAG laser. Standalone lines and hatched surfaces obtained with different laser parameters are characterized by scanning electronic microscopy coupled with EDS analysis, micro‐Raman, XRD and X‐ray photoelectron spectroscopy (XPS). A set of surfaces having featureless and saw‐tooth morphologies of different roughnesses is modified with octylphosphonic acid (OPA). The effect of surface roughness on the efficiency of OPA grafting is investigated using XPS. It is found that the organic load on the chemically modified surfaces increases with surface roughness. The apparent thickness of the OPA layers is estimated using a standard uniform overlap model and considering the correction due to the corrugated appearance of the laser‐treated surfaces. The wetting properties of the surfaces before and after chemical modification are compared. The laser‐treated surfaces show superhydrophilic behavior consistent with Wenzel model. On the other hand, the chemically modified surfaces demonstrate a strong increase in hydrophobicity along with the roughness increase, in agreement with the Cassie–Baxter model.