Search Results (1,669)

A new type of laminated flooring decorated by resin impregnated paper (LWFWRIP) was designed, with the advantages of low formaldehyde emission, improved flame retardant, and high wear resistance. The structure of this new type of wood flooring is based on the ordinary laminated flooring, followed by a decorative layer of thin wood pieces, and then the transparent improved flame retardant, wear-resistant paper is added to the top. It is found that the hot-pressing temperature is the most significant factor affecting the adhesion of resin impregnated paper. The optimal hot-pressing parameters are selected as the hot-pressing pressure of 3.5 MPa, hot-pressing temperature of 180 °C, and hot-pressing time of 40 s. The new laminated flooring was improved with high flame retardant, high wear-resistant, combined with the conventional advantages of both solid wood composite flooring and reinforced wood flooring. The new laminated flooring decorated by resin impregnated paper has broad application prospects. Full article

This study outlines a method for preparing a complex involving glycoluril and melamine (GU-ME). The structure of the resultant complex was analyzed using IR and NMR spectroscopy. In the subsequent phase, the polymer GUMEFA was derived from the resultant complex, employing hydroxyethylidene diphosphonic acid (HEDP) as a sustainable plasticizer, with a proposed chemical mechanism for its formation. The molecular weight of the resulting GUMEFA was analyzed, and the formation chemistry was proposed. GUMEFA was characterized, and its free formaldehyde and methylol group contents were investigated. It was observed that GUMEFA prepared with HEDP contained approximately 1.15–1.34 wt.% free formaldehyde and 1.56–0.54 wt.% methylol groups. These findings provide valuable insights for developing resins of different compositions and applications, thereby paving the way for producing composite materials with tailored properties. Full article

Phase change energy storage microcapsules were synthesized in situ by using melamine-formaldehyde–urea co-condensation resin (MUF) as wall material, n-octadecane (C18) as core material and styryl-maleic anhydride copolymer (SMA) as emulsifier. Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry and thermogravimetric analysis were used to study the effects of emulsifier type, emulsifier dosage, core–wall ratio and pH on the morphology and thermal properties of microcapsules. The results show that the pH of core material and the ratio of core to wall have a great influence on the performance of microcapsules. SMA emulsifiers and MUF are suitable for the encapsulation of C18. When the pH is 4.5 and the core–wall ratio is 2/1, the latent heat and encapsulation efficiency of phase transition reaches 207.3 J g⁻¹ and 84.7%, respectively. The prepared phase-change microcapsules also have good shape stability and thermal stability. Full article

The Tula industrial area in Central Mexico comprises, among other industries, a refinery and a thermoelectric power plant. It is well known for its constant emissions of gases into the atmosphere and considered an important area where pollutants released into the atmosphere have an influence on local and regional air quality. During March and April 2017, a field campaign was conducted with the objective of quantifying formaldehyde (HCHO), sulfur dioxide (SO₂), and nitrogen dioxide (NO₂) emissions from this industrial area using mobile differential optical absorption spectroscopy (DOAS) instruments. Calculated average emissions of the Francisco Perez Rios Power Plant and the Miguel Hidalgo Refinery were 3.14 ± 2.13 tons per day of HCHO, 362.08 ± 300.14 tons per day of SO₂, and 24.76 ± 12.82 tons per day of NO₂. From the measurements conducted, the spatial distribution patterns of SO₂, NO₂, and HCHO were reconstructed, showing a dispersion pattern of SO₂ and NO₂ towards the southwest of the industrial complex, impacting agricultural and urban areas. Occasionally, and usually during the morning hours, SO₂ and NO₂ were dispersed towards the north or northeast of the industrial complex. In the case of HCHO, dispersion was observed towards the south and southeast of the industrial complex. The far-reaching implications of this study are that for the first time, formaldehyde emissions were quantified. In addition, a follow-up study was conducted regarding nitrogen dioxide and sulfur dioxide emissions from the Tula Industrial area. Full article

7-Azaindoles are compounds of considerable medicinal interest. During development of the structure–activity relationship for inhibitors of the colony stimulated factor 1 receptor tyrosine kinase (CSF1R), a specific 2-aryl-1H-pyrrolo[2,3-b]pyridin-4-amine was needed. Two different synthetic strategies were evaluated, in which the order of the key C-C and C-N cross-coupling steps differed. The best route relied on a chemoselective Suzuki–Miyaura cross-coupling at C-2 on a 2-iodo-4-chloropyrrolopyridine intermediate, and subsequently a Buchwald–Hartwig amination with a secondary amine at C-4. Masking of hydroxyl and pyrroles proved essential to succeed with the latter transformation. The final trimethylsilylethoxymethyl (SEM) deprotection step was challenging, as release of formaldehyde gave rise to different side products, most interestingly a tricyclic eight-membered 7-azaindole. The target 2-aryl-1H-pyrrolo[2,3-b]pyridin-4-amine (compound 3c) proved to be 20-fold less potent than the reference inhibitor, confirming the importance of the N-3 in the pyrrolopyrimidine parent compound for efficient CSF1R inhibition. Full article

Perovskite oxide LaFeO₃(LFO) emerges as a potential candidate for formaldehyde (HCHO) detection due to its exceptional electrical conductivity and abundant active metal sites. However, the sensitivity of the LFO sensor needs to be further enhanced. Herein, a series of La_xIn_1-xFeO₃ (x = 1.0, 0.9, 0.8, and 0.7) nanofibers (L_xIn_1-xFO NFs) with different ratios of La/In were obtained via the electrospinning method followed by a calcination process. Among all these L_xIn_1-xFO NFs sensors, the sensor based on the L_0.8In_0.2FO NFs possessed the maximum response value of 18.8 to 100 ppm HCHO at the operating temperature of 180 °C, which was 4.47 times higher than that based on pristine LFO NFs (4.2). Furthermore, the L_0.8In_0.2FO NFs sensor also exhibited a rapid response/recovery time (2 s/22 s), exceptional repeatability, and long-term stability. This excellent gas sensing performance of the L_0.8In_0.2FO NFs can be attributed to the large number of oxygen vacancies induced by the replacement of the A-site La³⁺ by In³⁺, the large specific surface area, and the porous structure. This research presents an approach to enhance the HCHO gas sensing capabilities by adjusting the introduced oxygen vacancies through the doping of A-sites in perovskite oxides. Full article

The preparation of traditional wood-based panels mostly uses adhesives such as urea-formaldehyde resin and phenolic resin, which not only consumes petrochemical resources but also releases formaldehyde, posing potential health risks to the human body. Lignin, a natural adhesive in plant cells, is characterized by high reactivity, and it is expected to aid in the development of a new generation of green formaldehyde-free adhesives. However, current studies of lignin adhesives have revealed that while strides have been made in reducing formaldehyde emissions, its residual presence remains a concern, an issue which is compounded by inadequate water resistance. Dehydrogenated Polymer (DHP) has a lignin-like structure and good water resistance, offering a new option for the development of formaldehyde-free adhesives. In this paper, DHP and glucuronic acid were reacted with each other in a simulated hot-pressing environment to obtain DHP-glucuronic acid complex, and then the structure of the complex was characterized by infrared nuclear magnetic resonance to verify whether DHP can be efficiently connected with hemicellulose components under hot-pressing conditions. The results showed that the thermal condensation reaction of DHP and glucuronic acid can generate ester bonds at the Cα position in a simulated hot-pressing environment. This paper explores the thermal condensation mechanism of DHP and glucuronic acid, which is helpful for understanding the bonding process between adhesives and components of wood-based panels in the hot-pressing process, and provides key theoretical support for the design of more sustainable lignin adhesives. Full article

Studies of the impact of biomass burning and the emissions of trace gases from biomass burning, especially using long-term observations, are scarce in China. We utilize solar absorption spectra obtained via ground-based high-resolution Fourier transform infrared (FTIR) spectroscopy to retrieve the atmospheric total columns and vertical profiles of carbon monoxide (CO), formaldehyde (H₂CO), and hydrogen cyanide (HCN) in Hefei, China. Seasonal and interannual variability in the three gases from 2016 to 2022 are analyzed. Atmospheric CO shows significant seasonal variations, peaking during spring and winter, and declining during summer, with a seasonal amplitude of 8.07 × 10¹⁷ molecules cm⁻² and a seasonal variability of 29.35%. H₂CO and HCN have similar seasonal patterns to each other, with high concentrations in summer and low concentrations in winter. The seasonal amplitude of H₂CO and HCN are 1.89 × 10¹⁶ molecules cm⁻² and 2.32 × 10¹⁵ molecules cm⁻², respectively, with a seasonal variability of 133.07% and 34.69%, respectively. The means of the annual variation rate for CO, H₂CO, and HCN are (−2.67 ± 2.88)% yr⁻¹, (2.52 ± 12.48)% yr⁻¹ and (−3.48 ± 7.26)% yr⁻¹, respectively. To assess the influence of biomass burning on the variations in column concentrations of the three gases, the correlation between CO, H₂CO, and HCN was analyzed. The months during which the monthly correlation coefficient between CO and H₂CO with HCN exceeds 0.8, and the fire radiative power (FRP) observed by satellites is larger than its monthly average are regarded as a biomass-burning occurrence in Anhui province. Additionally, the enhancement ratios of ΔH₂CO/ΔCO and ΔHCN/ΔCO were calculated for the periods impacted by the biomass burning. Finally, backward trajectory cluster analysis and the potential source contribution function (PSCF) calculation identified the air mass transport pathways and the potential source areas at the Hefei site. Full article

The objective of this study was to evaluate the applicability of zeolite Y as a catalyst for producing bisphenol F (BPF) from phenol and formaldehyde. Catalyst extrudates were prepared by extrusion after adding pseudoboehmite sol (PS) and Ludox (Lu) as alumina and silica binders, respectively. The compressive strength of the catalyst extrudates increased with the addition of Ludox. However, the formaldehyde conversion decreased as more Ludox was used as a binder, resulting in a decrease in the yield of BPF. This decrease is attributed to the reduction in the total amount of acid sites caused by the addition of Ludox. In this study, the Y_PS5_Lu5 catalyst was selected as the most suitable for BPF synthesis. In the BPF synthesis over the Y_PS5_Lu5 catalyst in a catalyst basket reactor, the optimum reaction temperature was determined to be 110 °C. The effect of stirring speed on the yield of BPF was found to be negligible in the range of 200 rpm to 350 rpm. The spent catalyst was able to recover a specific surface area and reaction activity similar to those of a fresh catalyst through regeneration in an air atmosphere at 500 °C. When the Y_PS5_Lu5 extruded catalyst was used in a continuous reaction in a fixed-bed reactor, there was no noticeable deactivation of the catalyst at low space velocities of the reactants. However, when the space velocity was increased to 18.0 h⁻¹, catalyst deactivation was clearly observed. This suggests that periodic regeneration of the catalyst is inevitable in a continuous reaction using the Y_PS5_Lu5 extruded catalyst. Full article

The Total Carbon Column Observing Network (TCCON) and the Infrared Working Group of the Network for the Detection of Atmospheric Composition Change (NDACC-IRWG) are two ground-based networks that provide the retrieved concentrations of up to 30 atmospheric trace gases, using solar absorption spectrometry. Both networks provide reference measurements for the validation of satellites and models. TCCON concentrates on long-lived greenhouse gases (GHGs) for carbon cycle studies and validation. The number of sites is limited, and the geographical coverage is uneven, covering mainly Europe and the USA. A better distribution of stations is desired to improve the representativeness of the data for various atmospheric conditions and surface conditions and to cover a large latitudinal distribution. The two successive Fiducial Reference Measurements for Greenhouse Gases European Space Agency projects (FRM4GHG and FRM4GHG2) aim at the assessment of several low-cost portable instruments for precise measurements of GHGs to complement the existing ground-based sites. Several types of low spectral resolution Fourier transform infrared (FTIR) spectrometers manufactured by Bruker, namely an EM27/SUN, a Vertex70, a fiber-coupled IRCube, and a Laser Heterodyne spectro-Radiometer (LHR) developed by UK Rutherford Appleton Laboratory are the participating instruments to achieve the Fiducial Reference Measurements (FRMs) status. Intensive side-by-side measurements were performed using all four instruments next to the Bruker IFS 125HR high spectral resolution FTIR, performing measurements in the NIR (TCCON configuration) and MIR (NDACC configuration) spectral range. The remote sensing measurements were complemented by AirCore launches, which provided in situ vertical profiles of target gases traceable to the World Meteorological Organization (WMO) reference scale. The results of the intercomparisons are shown and discussed. Except for the EM27/SUN, all other instruments, including the reference TCCON spectrometer, needed modifications during the campaign period. The EM27/SUN and the Vertex70 provided stable and precise measurements of the target gases during the campaign with quantified small biases. As part of the FRM4GHG project, one EM27/SUN is now used as a travel standard for the verification of column-integrated GHG measurements. The extension of the Vertex70 to the MIR provides the opportunity to retrieve additional concentrations of N₂O, CH₄, HCHO, and OCS. These MIR data products are comparable to the retrieval results from the high-resolution IFS 125HR spectrometer as operated by the NDACC. Our studies show the potential for such types of spectrometers to be used as a travel standard for the MIR species. An enclosure system with a compact solar tracker and meteorological station has been developed to house the low spectral resolution portable FTIR systems for performing solar absorption measurements. This helps the spectrometers to be mobile and enables autonomous operation, which will help to complement the TCCON and NDACC networks by extending the observational capabilities at new sites for the observation of GHGs and additional air quality gases. The development of the retrieval software allows comparable processing of the Vertex70 type of spectra as the EM27/SUN ones, therefore bringing them under the umbrella of the COllaborative Carbon Column Observing Network (COCCON). A self-assessment following the CEOS-FRM Maturity Matrix shows that the COCCON is able to provide GHG data products of FRM quality and can be used for either short-term campaigns or long-term measurements to complement the high-resolution FTIR networks. Full article

Eucalyptus-based glued laminated timber (glulam) was produced to determine the feasibility of a non-destructive method (drilling resistance) to predict the properties of structural elements and add value to lower-quality hardwood species. Glulam was manufactured with formaldehyde (Resorcinol), reference condition, and bio-based (Castor oil-based) adhesives in two assembly schemes, the core composed either of two continuous lamellae each 105 cm long, or of two formed by the juxtaposition of shorter boards (35 and 55 cm). The shear strength of the glue line (f_v0), modulus of elasticity (E_c90), and strength (f_c90) in compression perpendicular to the grain; delamination (DL); and main and extended glue line thicknesses were evaluated. The Resistograph equipment was used to perform the perforation perpendicular to the glue line (samples extracted from the glulam elements) to correlate the properties. The results of this research demonstrate that the scheme of the boards had little effect on the physical and mechanical properties evaluated (except the main glue line and delamination), and the drilling resistance (DR) presents a significant correlation with practically all properties evaluated (variations in density values and other properties are explained by variations in DR values), making it possible to estimate E_c90 and f_c90 with desired precision (R²_adj ≈ 80%). This highlights the feasibility of using this methodology in the quality control of glulam elements. It is concluded that regardless of the adhesive, elements comprising a 105 cm-length core and external lamellae (T1 and control) are indicated for external use, presenting low delamination. Short-length central lamellae adhesively glued with PUR (T2) are not recommended for external applications due to their susceptibility to delamination. However, T2 is indicated for internal environments due to its low production cost. This study also proved the efficiency of using models based on drilling resistance to estimate wood density and its resistance to compression perpendicular to the fiber. Full article

Plywood is lightweight, strong, and durable, making it a widely used material in building decoration and furniture areas. In this study, formaldehyde-free, high-strength plywood was prepared through the incorporation of carbon fiber fabrics (CFFs) as reinforcement layers and their bonding with maleic anhydride polyethylene (MAPE) films. Various tests were performed to assess the impact of the carbon fiber fabric positioning on the physical and mechanical properties of plywood, including tensile shear strength, flexural strength, water absorption, thickness swelling, and electro-thermal properties. The results revealed that the plywood with CFFs exhibited significantly higher mechanical properties than plywood without CFFs. Particularly, the addition of CFFs increased the tensile strength of the plywood by nearly 54.43%, regardless of the CFFs’ position. The symmetric placement of CFFs near the bottom and upper layers of the plywood resulted in a maximum modulus of rupture of 85.6 MPa. These findings were validated by numerical simulations. Scanning electron microscopy analysis of the plywood microstructures revealed that MAPE penetrated both the vessels and xylem of the wood veneers and the pores of the CFFs, thereby improving the mechanical properties of the plywood. Plywood reinforced with CFFs exhibited increased water absorption and thickness swelling after immersion. Additionally, the placement of CFFs influenced the electro-thermal properties of the plywood. Plywood with CFFs positioned near the bottom and upper surfaces exhibited superior thermal conductivity. Overall, this study presents a feasible method for developing high-performance, formaldehyde-free plywood and sustainable wood-based structural materials with potential applications in geothermal flooring. Full article

Evidence has previously shown that outer tunics (turnout coats) worn by firefighters at structural fires are contaminated with harmful chemicals which subsequently off-gas from the material. However, there is limited research on whether this phenomenon extends to wildland firefighter uniforms. This pilot study aimed to explore if the tunics of volunteer bushfire and forestry firefighters in Western Australia off-gas any contaminants after exposure to prescribed burns or bushfires, and whether there is a need to explore this further. Nine tunics were collected from firefighters following nine bushfire and prescribed burn events, with a set of unused tunics serving as a control. Chemical analysis was performed on these tunics to assess levels of acrolein, benzene, formaldehyde, and sulphur dioxide contamination. The assessment involved measuring chemical off-gassing over a 12 h period using infrared spectrometry. Tunics worn by firefighters appear to adsorb acrolein, benzene, formaldehyde, and sulphur dioxide from bushfire smoke and these contaminants are emitted from firefighting tunics following contamination at elevated concentrations. Further investigation of this research with a larger study sample will be beneficial to understand this phenomenon better and to determine the full extent and range of chemical contaminants absorbed by all firefighter clothing. Full article

Nondestructive methods are a fast and accurate way to obtain information about the mechanical properties of plywood panels. The objective was to determine the modulus of rupture and compare the modulus of elasticity (MOE) in plywood boards made with Pinus spp. and Eucalyptus urograndis using the destructive method of three-point static bending and the nondestructive method of ultrasound in parallel and perpendicular directions, as well as in complete board and test specimens, both with the ultrasound method and the correlation between the variables studied. The plywood boards evaluated were 18, 25 and 30 mm nominal thickness. Five structures were evaluated using pine and pine–eucalyptus veneers. Three boards were collected per structure, and 28 specimens were made from each board (14 in a parallel direction and 14 in a perpendicular direction). The elastic modulus was determined by the ultrasound method in complete plywood boards and in specimens obtained from them using the IML Micro Hammer^® equipment and through the conventional bending test, carried out in an Instron^® universal mechanical testing machine. The Tukey test of means (p < 0.05) shows that in the nominal thickness of 18 mm, the modulus of elasticity by ultrasound was lower compared to the result obtained by static bending in four of the five structures in the perpendicular direction and lower in all the structures evaluated in the parallel direction; while in the nominal thickness of 25 and 30 mm, it was greater in all structures and in both directions. The results of static bending by ultrasound, in complete boards and specimens, show that the only significant difference (p < 0.05) occurs in the nominal thickness of 30 mm in the treatment made with pine–eucalyptus with urea formaldehyde resin being lower in the parallel direction and in complete boards The correlation between the modulus of elasticity determined on specimens using the nondestructive method and the destructive method was r = 0.75 and Pr < 0.05; while comparing the nondestructive method on test specimens and complete plywood panels, r = 0.73 and Pr < 0.05 were obtained. It is concluded that the mechanical bending property of plywood boards can be characterized by the ultrasound method. Full article

The misuse of antibiotics in veterinary medicine presents significant challenges, highlighting the need for alternative therapeutic approaches such as antibody drugs. Therefore, it is necessary to explore the application of antibody drugs in veterinary settings to reduce economic losses and health risks. This study focused on targeting the F4ac subtype of the FaeG protein, a key adhesion factor in enterotoxigenic Escherichia coli (ETEC) infections in piglets. By utilizing formaldehyde-inactivated ETEC and a soluble recombinant FaeG (rFaeG) protein, an antibody library against the FaeG protein was established. The integration of fluorescence-activated cell sorting (FACS) and a eukaryotic expression vector containing murine IgG Fc fragments facilitated the screening of anti-rFaeG IgG monoclonal antibodies (mAbs). The results demonstrate that the variable regions of the screened antibodies could inhibit K88-type ETEC adhesion to IPEC-J2 cells. Furthermore, in vivo neutralization assays in mice showed a significant increase in survival rates and a reduction in intestinal inflammation. This research underscores the potential of antibody-based interventions in veterinary medicine, emphasizing the importance of further exploration in this field to address antibiotic resistance and improve animal health outcomes. Full article