This work examined effects of the synthesis method and melamine content of melamine-urea-formaldehyde (MUF) resins on the bond-line features (i.e. resin penetration and bond-line thickness) in ...plywood. Two synthesis methods (MUF-A and MUF-B) and three melamine contents (5, 10, and 20%) were employed to prepare MUF resins. The MUF-A resins at three melamine contents were prepared by a simultaneous reaction of melamine, urea, and formaldehyde, while the MFU-B resins were prepared by reacting melamine at the same levels with formaldehyde followed by urea.
The results showed that higher melamine content increased the viscosity of MUF-A and MUF-B resins. The resin penetration of MUF-A resins decreased by 48% while those of MUF-B resins increased by 16% at 20% melamine content. As a result, the MUF-A resins had greater bond-line thickness than those of MUF-B resins as the melamine content increased. The MUF-B resins resulted in thinner bond-line and greater resin penetration compared to those of MUF-A resins. The results suggested that MUF-B resins prepared with 20% melamine content had a proper combination of resin penetration and bond-line thickness that could produce plywood panel with a better adhesion performance. KCI Citation Count: 9
Melamine-urea-formaldehyde (MUF) resin was synthesized by adding melamine with a first and second portion of urea, named M1 and M2, respectively. Different allocation proportions of M1:M2 (4:0, 3:1, ...2:2, 1:3, and 0:4) were used to develop five MUF (MUF-1, 2, 3, 4, and 5) resins with an F/(U+M) molar ratio of 1.05. The chemical structures, curing behaviors, and cross-section morphology of the resins were characterized. Three-ply plywood was fabricated to evaluate wet shear strength and formaldehyde emission. Results showed that when the melamine allocation proportion was increased from 0:4 to 4:0, the total methylene ether group content increased, the curing rate was elevated, and a heterogeneous cross-section of the cured resin formed, which led to a wet shear strength increase of 42.11%. When the melamine allocation proportion decreased, the free melamine content increased, the pot life was prolonged, and a highly homogeneous morphology was formed, which resulted in a decrease of 42.86% in formaldehyde emission of the resulting plywood. These results suggested that a high melamine allocation proportion, meaning that more of the MUF resin was added initially, improved the water resistance of the resulting resin, whereas a low melamine allocation proportion decreased the formaldehyde emission reduction of the resulting plywood.
Brewer's spent grain (BSG) is the richest by-product (85%) of the beer-brewing industry, that can be upcycled in a plentiful of applications, from animal feed, bioethanol production or for removal of ...heavy metals from wastewater. The aim of this research is to investigate the mechanical, physical and structural properties of particleboard manufactured with a mixture of wood particles and BSG gradually added/replacement in 10%, 30% and 50%, glued with polymeric diisocyanate (pMDI), urea-formaldehyde (UF) and melamine urea-formaldehyde (MUF) adhesives. The density, internal bond, modulus of rupture, modulus of elasticity, screw withdrawal resistance, thickness swelling and water absorption were tested. Furthermore, scanning electron microscopy anaylsis was carried out to analyze the structure of the panels after the internal bond test. Overall, it was shown that the adding of BSG decreases the mechanical performance of particleboard, due to reduction of the bonding between wood and BSG particles. This decrease has been associated with the structural differences proven by SEM inspection. Interaction of particles with the adhesive is different for boards containing BSG compared to those made from wood. Nevertheless, decrease in the mechanical properties was not critical for particleboards produced with 10% BSG which could be potentially classified as a P2 type, this means application in non-load-bearing panel for interior use in dry conditions, with high dimensional stability and stiffness.
This work studied the effect of the synthesis parameters (i.e. synthesis method and melamine content) on the adhesion of cold-setting melamine-urea-formaldehyde (MUF) resins in wood bonding. Two ...types of cold-setting MUF resins were synthesized: MUF-A resins with three melamine contents (30, 40, and 50 wt%) prepared by the simultaneous reaction of urea, formaldehyde, and melamine, and MUF-B resins with the same melamine levels but synthesized by a sequential reaction process of melamine with formaldehyde and urea. The curing behaviors of both resins were characterized by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA), and their adhesion performance in the dry and wet states were compared in block-shear strength (BSS) and wood failure (WF) tests. As the melamine content increased, the viscosity and peak temperature (T
p
) of the resins increased. However, MUF-B resins showed lower activation energy (E
a
) than those of MUF-A resins. Dynamic and isothermal DMA scans also showed that MUF-B resins also had greater maximum storage modulus (E′
max
) than those of MUF-A resins in their neat resins and resins/wood composites, indicating stronger interphase adhesion and cohesion. Lower T
p
, lower E
a
, and higher E′
max
, of MUF-B resins than those of MUF-A resins resulted in higher BSS and WF of MUF-B resins in wood bonding. In particular, MUF-B resins with 40% melamine showed the highest BSS and WF. These results indicate that the MUF resin synthesis method is closely related to the adhesion performance in wood bonding.
LINC00941, also known as lncRNA-MUF, is an intergenic non-coding RNA located on chromosome 12p11.21. It actively participates in a complex competing endogenous RNA network, regulating the expression ...of microRNA and its downstream proteins. Through transcriptional and post-transcriptional regulation, LINC00941 plays a vital role in multiple signaling pathways, influencing cell behaviors such as tumor cell proliferation, epithelial–mesenchymal transition, migration, and invasion. Noteworthy is its consistently high expression in various tumor types, closely correlating with clinicopathological features and cancer prognoses. Elevated LINC00941 levels are associated with adverse clinical outcomes, including increased tumor size, extensive lymphatic metastasis, and distant metastasis, leading to poorer survival rates across different cancers. Additionally, LINC00941 and its associated genes are linked to various targeted drugs available in the market. In this comprehensive review, we systematically summarize existing studies, detailing LINC00941's differential expression, clinicopathological and prognostic implications, regulatory mechanisms, and associated therapeutic drugs. Our analysis includes relevant charts and incorporates bioinformatics analyses to verify LINC00941's differential expression in pan-cancer and explore potential transcriptional regulation patterns of downstream targets. This work not only establishes a robust data foundation but also guides future research directions. Given its potential as a significant cancer biomarker and therapeutic target, further investigation into LINC00941's differential expression and regulatory mechanisms is essential.
An alternative approach to producing a wood-plastic composite (WPC) from wood particles, aluminium trihydrate-filled poly(methyl methacrylate) (PMMA/ATH) waste powder, and melamine-urea-formaldehyde ...(MUF) resin is described. The surface of PMMA/ATH powder was modified with ureido- and amino-functional silane coupling agents at four different degrees of modification: 0.3%, 0.5%, 1.0%, and 2.0%. An X-ray photoelectron spectroscopy (XPS) analysis was executed on a silane-modified PMMA/ATH material, and the results revealed the presence of chemically bonded silanes on the PMMA/ATH surface. Contact angle measurements were also performed to calculate the surface free energies of the modified powders. Water contact angles of modified powders slightly decreased as surface free energy increased with the degree of surface modification. Mechanical tests of the composites showed that different degrees of surface modification had a significant influence on modulus of elasticity (MOE) and modulus of rupture (MOR) of the composite boards. However, there were no significant differences between the silanes used.
The aim of this study was to investigate the influence of three surfacing methods (peripheral planing, sanding and face milling) on the moisture-related performance of bonded ash assemblies (Fraxinus ...excelsior L.). The different surfaces were tested in combination with four adhesives: phenol-resorcinol-formaldehyde (PRF), melamine-urea-formaldehyde (MUF), polyurethane (PUR) and emulsion polymer isocyanate (EPI). For evaluation, the surface roughness was measured and surfaces and bonds were examined by means of scanning electron microscopy (SEM) and transmitted light microscopy, respectively. To analyze bond performance, tensile shear tests were carried out as per EN 302-1 and the resistance to delamination was determined according to EN 302-2. Microscopy and roughness measurements showed significant differences between the bonding surfaces, notably with regard to cell damage and the level of fibrillation. The surface texture had significant impact on shear and delamination results. While shear tests showed good bond performance when tested in dry condition, moisture treatment revealed differences between surfaces, in particular with regard to wood failure. Based on shear results, the most appropriate surfacing method to produce moisture-resistant bonds appeared to be face milling together with PRF. Delamination results varied strongly with the surfacing method and adhesive types. PRF and MUF showed highest resistance to delamination with sanded surfaces, possibly because damaged cells helped to dissipate strain. PUR and EPI provided lower moisture-related durability. For these adhesives, best results were obtained with face milled surfaces, probably because of a more homogenous strain dissipation in the glueline caused by fibrillation.
An analysis of a pyroprocessing safeguards methodology employing the Pu-to-244Cm ratio is presented. The analysis includes characterization of representative used nuclear fuel assemblies with respect ...to computed nuclide composition. The nuclide composition data computationally generated is appropriately reformatted to correspond with the material conditions after each step in the head-end stage of pyroprocessing. Uncertainty in the Pu-to-244Cm ratio is evaluated using the Geary-Hinkley transformation method. This is because the Pu-to-244Cm ratio is a Cauchy distribution since it is the ratio of two normally distributed random variables. The calculated uncertainty of the Pu-to-244Cm ratio is propagated through the mass flow stream in the pyroprocessing steps. Finally, the probability of Type-I error for the plutonium Material Unaccounted For (MUF) is evaluated by the hypothesis testing method as a function of the sizes of powder particles and granules, which are dominant parameters to determine the sample size. The results show the probability of Type-I error is occasionally greater than 5%. However, increasing granule sample sizes could surmount the weakness of material accounting because of the non-uniformity of nuclide composition. Keywords: Safeguards, MUF, Pyroprocessing, Nuclear material accountancy, Type-I error, Serpent
This paper proposes a short-term forecasting method for high-frequency broadcast Maximum Usable Frequency (MUF) based on Long Short-Term Memory (LSTM) to meet the demand for refined and precise ...high-frequency broadcast coverage. Based on the existing infrastructure of broadcast and television stations, we established an experimental verification system to collect data for approximately three years. Two links were selected based on data quality: Urumqi to Lhasa and Lanzhou to Lhasa. A short-term forecast of MUF was conducted using the data from these two links. Comparison and analysis were conducted between the forecasting results of our model and those of the REC533 model. Our proposed method outperforms the REC533 forecasting results overall, with a reduction in root mean square error (RMSE) of 0.66 MHz and an improvement in forecast accuracy of 14.77%. The comparison result demonstrates the feasibility and accuracy of our model.
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