Thin Ones Research Articles

Genesis of Intimal Thickening Due to Hemodynamical Shear Stresses.

This paper investigates intimal growth in arteries, induced by hemodynamical shear stress, through finite element simulation using the FEniCS computational environment. In our model, the growth of the intima depends on cross section geometry and shear stress. In this work, the arterial wall is modeled as three distinct layers: the intima, the media, and the adventitia, each with different mechanical properties. We assume that the cross section of the vessel does not change in the axial direction. We further assume that the blood flow is steady, non-turbulent, and unidirectional. Blood flow induces shear stress on the endothelium and stimulates the release of Platelet Derived Growth Factor (PDGF) which drives the growth. We simulate intimal growth for three distinct arterial cross section geometries. We show that the qualitative nature of intimal thickening varies depending on arterial geometry. For cross section geometries that are annular, the growth of the intima is uniform in the angular direction, and the endothelium stays circular as the intima grows. For non-annular cross section geometries, thicker intimas grow more compared to thinner ones, shear stress and intimal thickening are negatively correlated with the distance from the flow center, where the flow velocity is maximal. Over time, the maxima and minima of the curvature increase and decrease respectively, the PDGF concentration increases, and the lumen becomes more polygonal. The model provides a framework for coupling hemodynamics simulations to mathematical descriptions of atherosclerosis, both of which have been modeled separately in great detail.

Numerical modeling of the punching shear behavior of biaxially loaded RC footings

In this study, the punching shear behavior of footings under biaxial eccentric loads is numerically investigated. Load eccentricities usually encountered in practice were primarily investigated on flat slabs, whereby the research on footings is still limited. Since the structural behavior of thick footings is significantly different compared to that of thin ones due to fracture mechanics, further investigations are required. To gain a deep understanding of the punching shear behavior of footings under biaxial eccentric loads, a numerical investigation was conducted. A finite element model was developed and validated against multiple experimental results in terms of load-deflection behavior and crack patterns. The validated model was then employed to examine the effect of different biaxial load eccentricities, different shear spans to effective depth ratios, column sizes, and column shapes. Finally, the numerical results were used for analyzing the design approach of the latest version of Eurocode 2 (FprEC2-2023). The numerical results showed a gradual transition between a fully developed punching shear cone to a partially formed cone without shear crack formation on the less loaded side with increasing load eccentricities. Additionally, larger load eccentricities lead to significantly increased rotation of the footing accompanied by a reduction of the punching shear capacity. A more pronounced influence of the effect of unbalanced moments on the punching shear capacity was identified in footings with a larger shear span to effective depth ratio. Furthermore, the effect of column size was more pronounced in small shear spans under concentric loads, while the effect was greater in footings with a larger shear span to depth ratio under eccentric loads. However, the beneficial effect of a larger column size was more pronounced for eccentric loads compared to concentric loading. Overall, the results indicate a good agreement with the design approach of Eurocode (FprEC2) for square columns. However, in some cases, the prediction was underestimated. Modified approaches from the literature for considering the effect of load eccentricity were found to address the underestimated cases safely. The results of this study demonstrated the applicability of the new design approaches for eccentric punching shear in footings under biaxial eccentric loads.

3D surface defect map for assessing buccolingual profile of single tooth gaps following alveolar ridge preservation.

A new, non-invasive approach suggests using single intraoral optical scanning to analyze the ridge profile of single-tooth gaps following alveolar ridge preservation in the absence of a baseline scan. This method involves creating a three-dimensional (3D) surface map to identify and assess contour changes and ridge profiles based on the adjacent teeth. The present study was designed as a cross-sectional pilot analysis on a convenience sample of patients undergoing alveolar ridge preservation. Intraoral optical scans were taken on 23 patients, capturing data from 30 edentulous sites. The digital models were then imported into an image analysis software for a 3D surface defect map analysis performed by one examiner. This analysis characterized the buccolingual profile of the single tooth gap relative to the adjacent teeth. 10 linear divergence points, spaced 0.5 mm apart in a corona-apical direction, were identified at the midfacial aspect of the sites. Based on these points the sites were plotted and grouped in three different buccolingual profiles (linear, concave, and convex). Clinical parameters including Keratinized mucosa Width (KMW), and soft tissue phenotype with Colorvue biotype probes were also recorded. Three different buccolingual patterns (linear, convex, and concave) were identified. Seven sites exhibited a linear profile, 10 sites displayed a concave shape, and 13 showed a convex profile. The linear profile had surface discrepancies similar to the neighboring teeth. In contrast, the convex profile revealed mid-buccal discrepancy localized only at the crestal aspect, while the concave had an extended divergence ranging from 1 to 5 mm below the soft tissue margin. Univariate and multiple logistic regression analyses did not reveal any statistically significant variables influencing profilometric analysis; however, when combining phenotype and KMW, thick phenotypes demonstrated a higher proportion of concavity (OR = 4.83) compared to thin ones, suggesting a significant trend. With every 1 mm of increase in KMW, the probability of showing a concavity decreased (p = 0.057). A 3D surface defect map represents a useful tool for objectively quantifying ridge defects and profiles by assessing profilometric and surface differences compared to adjacent dentition using a single intraoral scan. This method also indicates that KMW may play a critical role in preventing concavity defects. The 3D defect map can guide decision-making during soft tissue augmentation procedures by emphasizing the specific location of the defect and providing more detailed insights into its localization. These parameters can enable the tailoring of flap management and soft tissue grafting strategies to address the patient's individual needs.

Numerical Modeling of Anisotropic Particle Diffusion through a Cylindrical Channel.

The transport of molecules and particles through single pores is the basis of biological processes, including DNA and protein sequencing. As individual objects pass through a pore, they cause a transient change in the current that can be correlated with the object size, surface charge, and even chemical properties. The majority of experiments and modeling have been performed with spherical objects, while much less is known about the transport characteristics of aspherical particles, which would act as a model system, for example, for proteins and bacteria. The transport kinetics of aspherical objects is an especially important, yet understudied, problem in nanopore analytics. Here, using the Wiener process, we present a simplified model of the diffusion of rod-shaped particles through a cylindrical pore, and apply it to understand the translation and rotation of the particles as they pass through the pore. Specifically, we analyze the influence of the particles' geometrical characteristics on the effective diffusion type, the first passage time distribution, and the particles' orientation in the pore. Our model shows that thicker particles pass through the channel slower than thinner ones, while their lengths do not affect the passage time. We also demonstrate that both spherical and rod-shaped particles undergo normal diffusion, and the first passage time distribution follows an exponential asymptotics. The model provides guidance on how the shape of the particle can be modified to achieve an optimal passage time.

Basic techniques for optimizing burn wound healing: insights from clinical practice

The purpose of this paper is to provide the author’s view on basic techniques to optimize burn wound healing. For burns that are partial thickness, the goal is to optimize re-epithelialization to reduce the chance of hypertrophic scarring. For deeper burns, there are principles that lead to better outcomes. For very small burns, such as on the hand, full-thickness skin grafts can be performed in the outpatient setting. For burns requiring split-thickness skin grafts, thicker grafts tend to contract less than thinner ones. Using wider skin grafts or breaking up straight seams with darts also leads to improved results. Choosing donor sites that either minimize scarring or can be hidden should also be considered. For the massive burn, one must still prioritize better grafts for more functional or cosmetic areas (face, hands). Early excision and coverage should reduce scarring. Despite the availability of newer technologies, simple strategies to treat the burn wound still lead to excellent results.

Impact of thermally induced stress gradient on magneto-impedance sensitivity of As-quenched and Joule annealed microwires

The investigation addresses the dependence of rapidly quenched (Co94 Fe6)72.5 Si12.5 B13 Cr2 microwire diameters on their phase transformation evidenced during devitrification and consequent giant magneto-impedance (GMI) behavior. Phase segregation / nucleation in thicker microwires as compared to thinner ones were detected through thermal studies. In addition to such nucleation, the stress effect was more pronounced in thinner microwires as evidenced from GMI output. Structural relaxation through Joule annealing further enhanced the properties. Appropriate choice of operating frequency, alternating current and Joule heating current density vis-à-vis microwire diameter is essential for sensor design.

Magic speed under radiation drag for the optically thick outflows and SS 433 jets

Abstract One of the promising mechanisms to explain the stable jet speed of SS 433 is the magic speed, which is established by the balance between radiation pressure and radiation drag (and gravity). We examine the magic speed in the optically thick sub-relativistic flows for several typical situations, such as plane-parallel and spherical cases, and show that it is difficult to establish the magic speed in the simple optically thick flows in contrast to the optically thin ones. Instead, we propose the funnel jets as an improved model. That is, we consider the optically thick flows in the funnel, which is formed by the supercritical accretion disk, and mass and radiation energy are injected from the funnel wall. In this model the mass-accretion rate determines the configuration of the funnel, the increasing mass-loss rate of jets, the radiative environments, and then the sub-relativistic magic speed is naturally established.

Sensitivity of ZnO Film-Based X-ray Sensors: A Comprehensive Study on the Effect of Thickness of ZnO Layer.

For all types of photosensors, efficient absorption of photons of particular interest is very essential. We report the effect of thickness of the ZnO layer in ZnO film-based X-ray sensors. A set of five samples Z1, Z2, Z3, Z4, and Z5 is developed by varying the thickness of the ZnO layer between 10 and 73 μm. The dark I-V characteristics of the sensors show a "pseudorectifying" type nature. A quantitative analysis of the dark currents reveals that the dark I-V characteristics are affected by space charge limited current (SCLC) due to intrinsic defects present in the ZnO films. The effect of the SCLC is prominent in the thicker films in comparison to the thinner ones. The sensors show high signal-to-noise (S/N) ratio below 5.0 V bias voltage. The S/N ratio is found to increase with the thickness of the ZnO layer due to efficient absorption of X-ray photons. The photoresponse characteristics of the sensors against dose rate are sublinear between 0.015 and 0.234 Gy/s. The photoresponse time of the sensors are found to be nearly 1 s. The sensitivities of Z1, Z2, Z3, Z4, and Z5 sensors at 4.5 V bias voltage for 0.234 Gy/s dose rate are estimated to be 55.51, 337.08, 312.01, 152.81, and 103.52 μC/Gy cm3, respectively. The sensitivity of the device is found to increase with increase in thickness of the ZnO layer and reaches an optimum level for the thickness of about 19-26 μm. Beyond this range, the sensitivity is found to decrease due to the Schubweg effect.

Quality characteristics, lysozyme activity, and albumen viscosity of fresh hatching duck eggs after a week's storage at various temperatures

The study aimed to analyze the qualitative features of Cherry Valley duck’ hatching eggs during storage at different temperatures. Eggs were divided into 3 equal groups with 30 eggs each: fresh egg and stored at 7 °C and 17 °C within one week. Qualitative analyses of duck eggs were carried out, considering the morphological composition, physicochemical characteristics, lysozyme activity, and albumen viscosity. The highest weight of yolk and its percentage was found in the 17 °C group. The weight and percentage of albumen were significantly the highest in the group of fresh eggs. Higher egg weight loss was observed in the group stored at higher temperatures. Higher thick albumen height and Haugh units were found in fresh eggs and eggs stored at 7 °C. Different temperatures of egg storage did not affect lysozyme activity in thick and thin albumen. Stored eggs were characterized by lower albumen viscosity only at a shear rate of 10 rpm. The higher viscosity of thick albumen compared to thin ones was demonstrated at 10 and 20 rpm shear rates. The presented research results indicate a large diversity of selected qualitative indicators of hatching duck eggs, which may affect their storage and suitability for incubation.

Role of mechanotransduction on decision making for treatment of chronic wounds

AbstractThe objective of this study is to take an initial step to determine and interpret the extents to which biophysical wound dressing properties impact mechanotransduction within a wound tissue. Current experimental techniques make it challenging to investigate many of the complexities of the wound healing process. Thus, the purpose of this study is to begin with computational models and theoretical descriptions that propose predictions and explanations of the role of various mechanical wound dressing characteristics on mechanotransduction in wound tissues. Three‐dimensional models of wound tissue and wound dressings have been developed to analyze how von Mises stresses are distributed within the tissue models. Our results show that shorter ellipsoid dressings lead to highest stresses within the wound tissue where dressing's thickness and stiffness don't show a significant impact. When using a rectangular dressing, shorter, softer, thinner ones lead to high stress transmission to a wound tissue.

Seeded‐Growth of PCN‐224 onto Plasmonic Nanoparticles: Photoactive Microporous Nanocarriers

This study addresses the fabrication of microporous plasmonic nanocomposites (NCs) by using plasmonic nanoparticles (i.e., gold bipyramids, AuB) as seeds to grow microporous shells, specifically, metal–organic frameworks (MOF) PCN‐224 of increasing thickness from 69 to 138 nm. This method is based on using a previously synthesized Zr6‐oxo cluster and unfolds at room temperature. Notably, it is demonstrated that the concentration of the AuB seeds determines both the yield of NCs and the resultant thickness of the PCN‐224 shell, illustrating the seeded growth mechanism. Furthermore, it is found that the thermoplasmonic response of the NCs is dominated by the thickness of the microporous shell, with thicker shells having enhanced thermal confinement properties than thinner ones. As a proof of concept, the NCs are loaded with cresyl violet (CV), a lysosomal fluorescent marker. This serves to demonstrate the thermoplasmonic‐induced intracellular release of CV by the photostimulation of the AuB's plasmonic near‐infrared (NIR) band. Moreover, the NCs display exceptional efficacy as photodynamic agents when photostimulated at the PCN‐224's Soret band. In summary, this study offers a facile, efficient, and reproducible methodology for the fabrication of NCs with a controlled geometry while unlocking new possibilities in the field of nanoMOFs as multifunctional theranostic probes.

On the modelling of distorted thin-walled stiffened panels via a scale reduction approach for a simplified structural stress analysis

To reduce the weight of cruise ships, the shipbuilding industry is interested in thin-walled superstructures, where the thickness of butt-welded plates in stiffened panels is under 5 mm. Compared to thick plates, thin ones can develop severe welding-induced distortions, which limit the validity of recommended early-design structural stress assessment methods. Therefore, computationally costly 3D non-linear numerical analysis must be used. For a quick and effective early design, this paper investigates on simplified computational models for thin-walled panels under uni-axial tension, considering the distortions measured on 4-mm thick, full-scale ship-deck panels. A 2D simply-supported analytical plate is shown to be sufficiently accurate (i.e., error <10%) at 150MPa for a distortion with maximum slope within 0.02rad and amplitude smaller than the thickness (t). Moreover, a 1D beam numerical analysis efficiently predicts local stresses around the butt weld when the maximum distortion amplitude is below 0.6×tmm. The distortion needs to be considered at least up to a length of half of the plate width from the weld location and can represent longitudinal profiles within 60% of the plate width. In conclusion, the early structural stress assessment of thin-walled panels can be significantly simplified, thus helping bridge the gap between complex numerical analysis and simplified analytical solutions.

Thiols Modulated Gold Nanorods Self-Assembly: Indirect Hydrophobic Effects Instead of Direct Electrostatic/Hydrogen Bonds Attraction.

For nanocrystals (NCs) self-assembly, understanding the chemical and supramolecular interactions among building blocks is significant for both fundamental scientific interests and rational nanosuperstructure construction. However, it has remained an extreme challenge for many self-assembly systems due to the lack of appropriately quantitative approaches for the corresponding exploration. Herein, by combination of the proposed colorimetric method for cationic surfactant quantitation and all-atom simulations, we manage to present a clear chemical picture for the thiol molecules modulated self-assembly of gold nanorods (GNRs), one of the earliest and most convenient methods for the fabrication of freestanding GNR self-assemblies. It is revealed that the self-assembly of GNRs is driven by the hydrophobic effects of the alkyl chains of the modified cationic surfactants, as their bilayer structure is destroyed by the added thiol molecules. In other words, the actual roles of the thiol molecules for causing GNRs assembly are indirectly inductive effects instead of the previously believed direct electrostatic attraction and/or hydrogen-bond linking effects of the binding thiol molecules. Furthermore, the GNRs exhibit diameter-dependent assembly behaviors: thicker GNRs tend to adopt the end-to-end assembly mode, while thin ones prefer the side-by-side assembly mode, further demonstrating that hydrophobic effects among the build blocks are the driving force for the GNRs assembly.

Durability Properties of Macro-Polypropylene Fiber Reinforced Self-Compacting Concrete.

Concrete is one of the most commonly used construction materials; however, its durability plays a pivotal role in areas where the concrete is exposed to severe environmental conditions, which initiate cracks inside and disintegrate it. Randomly distributed short fibers arrest the initiation and propagation of micro-cracks in the concrete and maintain its integrity. Traditional polypropylene fibers are thin and encounter the problem of balling effects during concrete mixing, leading to uneven fiber distribution. Thus, a new polypropylene fiber is developed by gluing thin ones together, forming macro-polypropylene fibers. Thus, different amounts of fibers, 0-1.5% v/f with an increment of 0.5% v/f, are used in different grades of concrete to study their impact on durability properties, including resistance to freezing and thawing cycles, sulfate, and acid attacks. A total of 432 cube samples were tested at 28, 56, and 92 days. The results reveal that the maximum durability, in terms of compressive strength loss, is noted with a fiber content of 1% with improved resistance of 72%, 54%, and 24% against freeze-thaw cycles, sulfate attack, and hydrochloric acid attack, respectively, at 92 days. Thus, the resulting fiber-reinforced concrete may be effective in areas where these extreme exposure conditions are expected.

The effect of ureteral double J stent insertion on work performance in patients undergoing endoscopic stone treatment.

Despite the developments in the material of the double J (DJ) stents and the production of thinner ones of desired sizes, patients continue to experience troublesome DJ stent-related symptoms in their lives. This study aimed to determine how DJ stenting affects patients' work performance after endoscopic stone surgery. A total of 107 patients underwent placement of a ureteral stent after ureterorenoscopy (URS)/retrograde intrarenal surgery (RIRS), and only active and full-time working patients were included. All patients were asked to complete the validated Turkish version of the work performance score (WPS) questionnaire in the Ureteral Stent Symptom Questionnaire (USSQ) the day before stent removal and again one month after stent removal. Of the participants, 32.7% (n = 35) were female and 67.3% (n = 72) were male; the mean age was 41 (19-80) years. The workday loss had no statistically significant correlation with patient BMI, stone size, or stent indwelling time (p >0.005); however, a statistically significant negative correlation was detected with patient age (r = -0.335, p <0.001). The medians of WPSs with the stent and without the stent were 6 (3-15) and 3 (3-12), respectively (p <0.001). Although DJ catheterization is a crucial tool for urological practice, it may increase the social and economic burden of patients due to reduced work performance and lost workdays. Therefore, limiting the duration of the DJ stent's stay and providing treatments to minimize patient symptoms will positively impact their professional lives. It would be beneficial to avoid DJ stenting in routine practice unless medically necessary.

Film thickness-induced optical and electrical modifications in large-area few-layer 2H-MoSe2 grown by MBE.

Here, we report on a detailed study of film thickness-induced effects on optical and electrical characteristics of ultra-thin MoSe2 films grown using molecular beam epitaxy (MBE) on a c-plane sapphire substrate. The layer-dependent optical and electrical responses are investigated for MoSe2 films with different thicknesses (1, 2, 4 and 7 layers). Spectroscopic ellipsometry (SE) reveals significant variation in optical constants with film thickness in the spectral range of 5.04 eV to 0.73 eV. As the thickness increases from 1 layer to 7 layers, the band gap of the materials also changes from 1.62 eV to 1.19 eV. The layer-dependent band diagram analysis shows that the conduction band to Fermi level energy gap changes from 0.50 eV to 0.40 eV as the film thickness changes from 1 layer to 7 layers, making thicker films more n-type than thinner ones. I-V measurement shows an increase in current from the order of 10-9 to 10-5 ampere at a voltage of 3 V as the film thickness increases from 1 layer to 7 layers, which is explained by the corresponding change in the band diagram and supported by a temperature-dependent I-V study. The findings of the study offer a pathway to tune the optical and electrical characteristics of MoSe2 by controlling the layer number which can be valuable for its electronic and optoelectronic device applications.

Tunable Release of Calcium from Chitosan-Coated Bioglass.

Bioglass presents a standard biomaterial for regeneration of hard tissues in orthopedics and dentistry. The notable osteo-inductive properties of bioglass are largely due to the release of calcium ions from it. However, this release is not easily controllable and can often be excessive, especially during the initial interaction of the biomaterial with the surrounding tissues. Consequently, this excessive release can deplete the calcium content of the bioglass, ultimately reducing its overall bioactivity. In this study, we have tested if applying biopolymer chitosan coatings of different thicknesses would be able to mitigate and regulate the calcium ion release from monodisperse bioglass nanoparticles. Calcium release was assessed for four different chitosan coating thicknesses at different time points over the period of 28 days using a fluorescence quencher. Expectedly, chitosan-coated particles released less calcium as the concentration of chitosan in the coating solution increased, presumably due to the increased thickness of the chitosan coating around the bioglass particles. The mechanism of release remained constant for each coating thickness, corresponding to anomalous, non-Fickian diffusion, but the degree of anomalousness increased with the deposition of chitosan. Zeta potential testing showed an expected increase in the positive double layer charge following the deposition of the chitosan coating due to the surface exposure of the amine groups of chitosan. Less intuitively, the zeta potential became less positive as thickness of the chitosan coating increased, attesting to the lower density of the surface charges within thicker coatings than within the thinner ones. Overall, the findings of this study demonstrate that chitosan coating efficiently prevents the early release of calcium from bioglass. This coating procedure also allows for the tuning of the calcium release kinetics by controlling the chitosan concentration in the parent solution.

Comparative Studies of GFRP Composites Using Pulsed Thermography and Transmission Terahertz Non-Destructive Testing Methods

Composites are materials that have replaced traditional construction materials in numerous applications in various fields. Due to the possibility of creating the required material properties, fiber-reinforced composites are most often used. Despite competition from carbon and aramid fibers, the earliest glass fibers produced are used in many applications. One of the areas where glass fiber reinforced composites (GFRP) make a significant contribution to structural applications is aviation. Because both during production and operation, composites are exposed to damage, which often occurs in the internal structure of the composite, works are being carried out to develop the most effective method of non-destructive testing to detect such damage. The article presents a comparison of the results of non-destructive testing of glass fiber-reinforced composite samples. A comparison of the results of the possibility of detecting defects in the form of milled holes of different diameters and depths inside the samples was made. These damages are not optically visible on both surfaces of the samples. In non-destructive testing, infrared thermography and transmission terahertz methods were used. The obtained results indicate a great possibility of using terahertz radiation, especially in thicker structures of the GFRP composite, where thermographic methods are not as effective as in thin ones.

Regenerated cellulose membranes for efficient separation of organic mixtures

Organic solvent nanofiltration (OSN) is a low-carbon technology for organic mixture separation that usually relies on non-renewable fossil-derived membranes. Cellulose, a biomass material with extensive sources and superior resistance to organic solvents, holds great promise in engineering OSN membranes. Here we studied the mass transport and separation properties of regenerated cellulose membranes (RCMs), which were made from wood pulp using ionic liquid as solvent by phase inversion method. By regulating membrane thickness from 150 μm to 350 μm, the solvent permeance and solute rejection can be finely tuned. The 350-μm-thick RCM membrane (RCM-350) displays better compaction resistance than the thinner ones and harvests high solute rejection with ethanol permeance reaching ∼ 30 L m−2 h−1 bar−1, outperforming the state-of-the-art polymeric membranes and showing long-term stability during cross-flow OSN. When used for solute separation, the RCM-350 membrane provides molecular selectivity of up to 294 and 68 for Alcian blue/Rifampicin and Alcian blue/Tetracycline mixtures, respectively, which depends on the mixture composition. Our findings reveal the potential of regenerated natural cellulose as a high-performance and sustainable alternative membrane material for separating organic mixtures.

Fire-Resistant Coatings, Obtained by Layer-by-Layer Assembly, in the System of Silicic Acid Gel – Diammonium Hydrogen Phosphate – Urea

The paper discusses the influence of flame retardant compositions obtained in the system of silicic acid sol (SiO2 sol) – flame retardants on the fire retardant properties of thin dense cotton fabrics and low density voluminous tapestry fabrics. The need to develop the optimal composition of a fire-retardant composition for a specific fabric, or to unify it for two main groups of fabric: thin and bulky low-density ones, is substantiated. Experimental coatings were obtained by applying SiO2 sol, which was obtained by the reaction between liquid glass and acetic acid, followed by application of flame retardant solutions (diammonium hydrogen phosphate (DAHP) and urea) by spraying or by the bath method. As a result of the optimization, using the central composite uniform rotatable plan of the second order, it was established that the main effect of the flame retardant is exerted by diammonium hydrogen phosphate (DAHP). The content or concentration of urea depends on the concentration of DAHP used: if diluted DAHP solutions (9–10 %) are used, trace amounts of urea (0–0.5 %) must be added. In the case of using a concentrated DAHP solution (18–20 %), the concentration of the urea solution should also be increased to 8–10 %.