Wood is a versatile and renewable resource utilized in a wide range of applications, including tools, furniture, construction, and advanced engineering structures. However, certain inherent ...properties of wood, such as moisture and ultraviolet (UV) degradation, impose limitations on its long-term durability and dimensional stability for outdoor applications. This research investigates the weathering durability of cross-laminated timber (CLT) blocks surface-treated with titanium dioxide (TiO2) nanoparticles synthesized via liquid-precursor flame spray pyrolysis (FSP), directly deposited onto the surface of CLT blocks, and thereby resulting in a porous TiO2 coating. This coating endows the CLT surface with superhydrophobic properties evidenced by a water contact angle of ≥150°. Results from scanning electron microscopy and X-ray diffraction show the coating to be comprised of crystalline, sub-100 nm individual and aggregated TiO2 particles with significant porosity. Even after an 8-week accelerated weathering test, a portion of the crystalline TiO2 particles remains on the CLT surface. The TiO2-treated CLT demonstrates enhanced resistance to discoloration and gloss change over 8-weeks of accelerated weathering conditions, which are evidenced by a total color difference (ΔE) that is 3–4 times lower than that of the untreated CLT in the initial two weeks, and 58% lower after 8 weeks of weathering. Furthermore, the TiO2-treated CLT exhibits fewer weathering defects, such as splits and cracks, than the untreated CLT. The enhanced weathering durability of the TiO2-treated CLT is attributed to reduced lignin degradation, which is supported by the Fourier-transform infrared spectroscopy analysis. The findings of this study suggest that the TiO2 coating by FSP offers a viable and cost-effective method for modifying engineered wood products for improving hydrophobicity and protecting against the deteriorating effects of UV irradiation and moisture exposure.
•TiO2 nanoparticles are applied to the surface of CLT blocks by flame spray pyrolysis (FSP).•The FSP process on CLT results in a TiO2 layer consisting of sub-100 nm TiO2 nanoparticles on CLT.•TiO2-treated CLT shows enhanced resistance to discoloration and weathering defects during an 8-week accelerated weathering test.•Enhanced protection against lignin degradation is attributed to the UV-absorbing properties of TiO2 nanoparticles.
Wood is a renewable resource and versatile material used in tasks ranging from tools and furniture to advanced engineering structures. Although wood is light, mechanically robust, environmentally ...friendly, and abundant, some inherent properties of wood, such as degradation due to moisture and UV radiation from sunlight, are less desirable for extended service life and dimensional stability. In this dissertation, a novel surface modification of wood is explored by depositing nano-sized titania particles on wood veneers and cross-laminated timber (CLT) blocks by liquid-precursor flame spray pyrolysis to confer reversible wettability switching and enhanced durability to UV irradiation. The reaction between a flame source and a titanium precursor in isopropyl alcohol under controlled air pressure created a micrometer-scale thin TiO2 coating on wood that turns the treated wood superhydrophobic with a water contact angle (WCA) of ≥150°. Morphological studies suggest the coating is comprised of sub-100 nm TiO2 individual and aggregated particles, creating a very porous microstructure. The coating consists of TiO2 rich in the anatase phase (>60%) with an average crystal size of 18 and 32 nm for the anatase and rutile phases, respectively. The wettability switching characteristics of the surface of TiO2-wood veneers from superhydrophobicity to superhydrophilicity (WCA ~0°) and again back to superhydrophobicity are examined through UV exposure (0.0032 W/m2 ), WCA measurements, and vacuum drying at ~0.14 mbar. The color and gloss spectrometry results of the TiO2-treated CLT samples indicate that the coating offered better resistance to discoloration and gloss change than the uncoated samples during the 8-week accelerated weathering conditions. The data shows that the FSP-treated CLT samples were more than two times more effective in preventing discoloration and changes in natural luster, as evidenced by the significant differences in L*, a*, b*, and gloss values. Moreover, the FSP treatment might have played a role in preventing weathering defects, such as splits and cracks. In addition, the FSP-treated CLT specimens were able to reduce variability in the samples more effectively than the control group. Overall, the findings of the study indicate that liquid-precursor FSP has the potential to serve as a facile, economically viable, and less energy-intensive approach to modify wooden surfaces for improved hydrophobicity, as well as to provide shielding against the deteriorating impacts of UV radiation and moisture exposure.
This research investigates the efficacy of liquid-precursor thermal spray coating (TSC) as a facile wood modification technique to bring hydrophobicity and UV durability to a wooden surface. The ...technique was successful in depositing Cu and TiO2 particles onto southern yellow pine (SYP) veneers by using copper azole, copper quaternary, and titanium tetraisopropoxide as the precursor solutions. Using optimized settings, the average coating surface coverage of > 90% and an average coating thickness of > 5 μm were obtained. The coatings displayed up to 4H rating in the film hardness scale and up to 3B rating in adhesion strength scale, suggesting reasonable mechanical durability under mild mechanical abrasion. TSC-modified wood with TiO2 created a water repellent layer, yielding a significant increase in hydrophobicity that changed the water contact angle from 57° to 126°. Accelerated weathering test results showed that the TSC-modified wood was more resistant to discoloration compared to unmodified wood.
Wood is a renewable resource and versatile material used in tasks ranging from tools and furniture to advanced engineering structures. Although wood is light, mechanically robust, environmentally ...friendly, and abundant, some inherent properties of wood, such as degradation due to moisture and UV radiation from sunlight, are less desirable for extended service life and dimensional stability. In this dissertation, a novel surface modification of wood is explored by depositing nano-sized titania particles on wood veneers and cross-laminated timber (CLT) blocks by liquid-precursor flame spray pyrolysis to confer reversible wettability switching and enhanced durability to UV irradiation. The reaction between a flame source and a titanium precursor in isopropyl alcohol under controlled air pressure created a micrometer-scale thin TiO2 coating on wood that turns the treated wood superhydrophobic with a water contact angle (WCA) of >=150°. Morphological studies suggest the coating is comprised of sub-100 nm TiO2 individual and aggregated particles, creating a very porous microstructure. The coating consists of TiO2 rich in the anatase phase (>60%) with an average crystal size of 18 and 32 nm for the anatase and rutile phases, respectively. The wettability switching characteristics of the surface of TiO2-wood veneers from superhydrophobicity to superhydrophilicity (WCA ~0°) and again back to superhydrophobicity are examined through UV exposure (0.0032 W/m2), WCA measurements, and vacuum drying at ~0.14 mbar. The color and gloss spectrometry results of the TiO2-treated CLT samples indicate that the coating offered better resistance to discoloration and gloss change than the uncoated samples during the 8-week accelerated weathering conditions. The data shows that the FSP-treated CLT samples were more than two times more effective in preventing discoloration and changes in natural luster, as evidenced by the significant differences in L*, a*, b*, and gloss values. Moreover, the FSP treatment might have played a role in preventing weathering defects, such as splits and cracks. In addition, the FSP-treated CLT specimens were able to reduce variability in the samples more effectively than the control group. Overall, the findings of the study indicate that liquid-precursor FSP has the potential to serve as a facile, economically viable, and less energy-intensive approach to modify wooden surfaces for improved hydrophobicity, as well as to provide shielding against the deteriorating impacts of UV radiation and moisture exposure.
Keywords: wood modification, flame spray pyrolysis, titania coating, superhydrophobic coating, particle deposition, wettability switching
This research investigates the efficacy of liquid-precursor thermal spray coating (TSC) as a facile wood modification technique to bring hydrophobicity and UV durability to a wooden surface. The ...technique was successful in depositing Cu and TiO2 particles onto southern yellow pine (SYP) veneers by using copper azole, copper quaternary, and titanium tetraisopropoxide as the precursor solutions. Using optimized settings, the average coating surface coverage of > 90% and an average coating thickness of > 5 μm were obtained. The coatings displayed up to 4H rating in the film hardness scale and up to 3B rating in adhesion strength scale, suggesting reasonable mechanical durability under mild mechanical abrasion. TSC-modified wood with TiO2 created a water repellent layer, yielding a significant increase in hydrophobicity that changed the water contact angle from 57° to 126°. Accelerated weathering test results showed that the TSC-modified wood was more resistant to discoloration compared to unmodified wood.
Caesarean Scar Endometriosis Sedhain, Nesuma; Dangal, Ganesh; Karki, Aruna ...
Journal of Nepal Health Research Council,
2018-Jan-01, 2018-01-01, 20180101, Letnik:
15, Številka:
3
Journal Article
Recenzirano
Endometriosis is a common benign gynecologic disorder defined as the presence of endometrial glands and stroma outside of the normal location. The overall prevalence is 8-15% in women of reproductive ...age group. Scar endometriosis is a rare disease, and is difficult to diagnose. It is commonly seen following obstetrical and gynecological surgeries. The symptoms are non-specific, typically involving abdominal wall pain at the incision site at the time of menstruation and palpable tender mass in the incision site. The diagnosis is frequently made only after excision of the diseased tissue and its histological analysis. We present here a case of abdominal wall scar endometriosis in a woman who had undergone a caesarean section four years ago. Surgical excision led to the diagnosis of scar endometriosis. The pathogenesis, diagnosis and treatment of this rare condition are discussed.
Caesarean Scar Endometriosis Nesuma Sedhain; Ganesh Dangal; Aruna Karki ...
Journal of Nepal Health Research Council,
01/2018, Letnik:
15, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Endometriosis is a common benign gynecologic disorder defined as the presence of endometrial glands and stroma outside of the normal location. The overall prevalence is 8–15% in women of ...reproductive age group. Scar endometriosis is a rare disease, and is difficult to diagnose. It is commonly seen following obstetrical and gynecological surgeries. The symptoms are non-specific, typically involving abdominal wall pain at the incision site at the time of menstruation and palpable tender mass in the incision site. The diagnosis is frequently made only after excision of the diseased tissue and its histological analysis. We present here a case of abdominal wall scar endometriosis in a woman who had undergone a caesarean section four years ago. Surgical excision led to the diagnosis of scar endometriosis. The pathogenesis, diagnosis and treatment of this rare condition are discussed. Keywords: Abdominal wall; caesarean section; painful scar; scar endometriosis.
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