•BaTiO3@g-C3N4 composites were prepared by a simple mixing–calcining method.•The composites exhibit enhanced photocatalytic activity compared to bare BaTiO3 and g-C3N4.•The effect of BQ, AO and ...ethanol on the photocatalytic efficiency was investigated.•O2 and h+ are the main active species responsible for the dye degradation.•OH radicals play a relatively small role in the photocatalytic reaction.
BaTiO3@g-C3N4 composites were prepared by a simple mixing–calcining method. SEM observation indicates that BaTiO3 nanoparticles are uniformly assembled onto the surface of g-C3N4 platelets. The photocatalytic activity of as-prepared BaTiO3@g-C3N4 composites were evaluated by the degradation of methyl orange (MO) under simulated sunlight irradiation, revealing that the composites exhibit enhanced photocatalytic activity compared to bare BaTiO3 and g-C3N4. This can be explained by the efficient separation of the photogenerated electron–hole pairs due to the migration of the carriers between g-C3N4 and BaTiO3; as a result, electrons and holes are increasingly available for the photocatalytic reaction. Hydroxyl radicals were detected by the photoluminescence technique using terephthalic acid as a probe molecule and are found to be produced equally on the irradiated BaTiO3 particles and BaTiO3@g-C3N4 composites. The effect of benzoquinone, ammonium oxalate and ethanol on the photocatalytic efficiency was also investigated. According to the experimental results, superoxide radicals and photogenerated holes are suggested to be the main active species responsible for the dye degradation, while hydroxyl radicals play a relatively small role in the photocatalytic reaction.
Aims
This study aimed to investigate the antifungal mechanism of carvacrol and eugenol to inhibit Rhizopus stolonifer and the control of postharvest soft rot decay in peaches.
Methods and Results
To ...investigate the antifungal mechanism, the effects of carvacrol and eugenol on the mycelium growth, leakages of cytoplasmic contents, mycelium morphology, cell membrane and membrane composition of R. stolonifer were studied. Carvacrol and eugenol both exhibited dose‐dependent antifungal activity against R. stolonifer, carvacrol at a concentration of 2 μl per plant and eugenol at a concentration of 4 μl per plant inhibited fungal growth completely. The two essential oils (EOs) increased cell membrane penetrability and caused the leakage of cytoplasm, nucleic acid and protein content. The observation using scanning electron microscopy and fluorescent microscopy showed modification of the hyphal morphology and breakage of the cell plasma membrane. Decreased ergosterol contents confirmed that the two EOs could destroy the membrane of R. stolonifer. For the in vivo test, the inhibition of soft rot disease and the induction of defence‐related enzymes were investigated. Carvacrol and eugenol significantly reduced the incidence and severity of soft rot decay in inoculated peaches. The best treatments for controlling soft rot decay were obtained at 0·5 μl l−1 for carvacrol and 1 μl l−1 for eugenol. The activities of defence‐related enzymes in peaches were also enhanced by fumigation with two EOs.
Conclusion
This study showed that carvacrol and eugenol could effectively inhibit the growth of R. stolonifer in vitro and successfully control the incidence of soft rot decay in honey peaches.
Significance and Impact of the Study
The above findings may be the main antifungal mechanism of carvacrol and eugenol on R. stolonifer. Furthermore, carvacrol and eugenol are helpful for their commercial application on the preservation of fresh fruit.
•LuFeO3 particles exhibit a good sonocatalytic activity toward the RhB degradation.•Various experimental factors on the sonocatalysis efficiency were investigated.•OH radicals are produced over the ...ultrasonic-irradiated LuFeO3 particles.•Ethanol leads to a quenching of OH radicals and a simultaneous decrease in RhB degradation.•OH radicals are the primary active species responsible for the dye degradation.
LuFeO3 particles with an average particle size of ∼200nm were synthesized via a polyacrylamide gel route. The sonocatalytic activity of LuFeO3 particles was evaluated by the degradation of Rhodamine B (RhB) under ultrasonic irradiation, revealing that they exhibit a good sonocatalytic activity. The effects of various experimental factors including ultrasonic frequency (f), reaction solution temperature (T), catalyst dosage (Ccatalyst), initial RhB concentration (CRhB), and pH value on the sonocatalysis efficiency were investigated. It is found that the former four factors have an important influence on the sonocatalytic degradation of RhB, where the best degradation conditions are obtained to be f=60kHz, T=40°C, Ccatalyst=4gL−1, and CRhB=5mgL−1. The pH value has a relatively small effect on the sonocatalytic degradation of RhB compared with other experimental factors. Hydroxyl (OH) radicals were detected by fluorimetry using terephthalic acid as a probe molecule, revealing that they are produced over the ultrasonic-irradiated LuFeO3 particles. The addition of ethanol leads to a quenching of OH radicals and a simultaneous decrease in the RhB degradation. This indicates that OH radicals are the primary active species responsible for the dye degradation.
Time and cost overruns have become one prominent issue for most construction projects around the world. Project costing and timeframe extension had been causing a lot of wastage and loss of ...opportunity for many parties involved. Therefore, this research was carried out to investigate the factors influencing time and cost overruns for high-rise construction projects in Penang, Malaysia. A set of questionnaires survey was distributed to the project managers who had been or currently involved in the high-rise building projects in Penang to get their input and perceptions for each factor identified as well as its frequency of occurrence. In order to rank all the factors gathered, the mean index of the most distinguishing factors and its frequency of occurrence were multiplied to get the severity index. The results revealed that for time overrun, the most predominant causes were due to design changes, inadequate planning and scheduling and poor labor productivity. Meanwhile, the predominant causes of cost overrun were poor pre-construction budget and material cost planning, inaccurate quantity take-off and materials cost increased by inflation. The significance of establishing the issues related to time and cost overruns for the high-rise building construction project is to provide a greater insight and understanding on the causes of delays, particularly among the main project players: contractors, client, and consultants.
► La0.7Ca0.3MnO3 nanoparticles with different sizes were prepared via a polyacrylamide gel route. ► Samples with average size of 30–50nm were obtained by using different chelating agents. ► ...Magnetocaloric properties of the samples were investigated.
La0.7Ca0.3MnO3 nanoparticles with different average sizes were prepared via a polyacrylamide gel route, where the particle size was tailored by using different chelating agents. The samples prepared by using the chelating agents acetic acid (S1), oxalic acid (S2), citric acid (S3) and EDTA (S4) have an average particle size of 30, 37, 45 and 50nm, respectively. The as-prepared particles are regularly shaped like spheres. Magnetocaloric properties of samples S1 and S4 that respectively have the smallest and largest particle size were systematically investigated. The paramagnetic–ferromagnetic transition temperature TC is observed to be 260K for sample S1 and 267K for sample S4. The nature of the magnetic phase transition at TC is determined to be second order. The magnetic entropy change is found to be extended over a wide range of temperature around TC, and its maximum value at an applied magnetic field of 15kOe is obtained to be 1.01 and 1.20Jkg−1K−1 for samples S1 and S4, respectively.
Recent studies demonstrate that chlorophyll a (chl a) concentrations in ocean surface waters can be significantly enhanced due to typhoons. The present study investigated chl a concentrations in the ...middle of the South China Sea (SCS) from 1997 to 2007. Only the Category 1 (minimal) Typhoon Hagibis (2007) had a notable effect on chl a concentrations. Typhoon Hagibis had a strong upwelling potential due to its location near the equator, and the forcing time of the typhoon (>82 h) was much longer than the geostrophic adjustment time (~63 h). The higher upwelling velocity and the longer forcing time increased the depth of the mixed-layer, which consequently induced a strong phytoplankton bloom that accounted for about 30% of the total annual chl a concentration in the middle of the SCS. Induction of significant upper ocean responses can be expected if the forcing time of a typhoon is long enough to establish strong upwelling.
A polyacrylamide gel method has been used to prepare SrTiO₃ nanoparticles. It is found that the choice of chelating agent has a great influence on the SrTiO₃ synthesis. The use of citric acid as the ...chelating agent leads to the synthesis of pure SrTiO₃ at a calcination temperature of 550°C. By using the chelating agent acetic acid, however, a much higher calcination temperature at 800°C is required to produce a single sample. The citric acid- and acetic acid-resulted samples exhibit both sphere- particle morphology, and have an average particle size of ~55nm and ~100nm, respectively. The photocatalytic properties of the as-prepared SrTiO₃ nanoparticles have been investigated by the degradation of Congo Red, RhB, MO, and MB under ultraviolet irradiation. The citric acid-resulted sample is found to exhibit a photocatalytic activity higher than the acetic acid-resulted sample, expectedly due to its relatively smaller particle size. In addition, different degradation efficiencies are found between the dyes, and the highest degradation efficiency is observed for Congo Red.
CaTiO₃nanoparticles of 30-40 nm in size were synthesized via a polyacrylamide gel route. Ag nanoparticles with size of 8-16 nm were deposited onto CaTiO₃particles by a photochemical reduction method ...to yield CaTiO₃@Ag composites. The photocatalytic activity of prepared samples was evaluated by degrading methyl orange under ultraviolet irradiation. It is demonstrated that Ag-decorated CaTiO₃ particles exhibit an enhanced photocatalytic activity compared to bare CaTiO₃ particles. After 60 min of photocatalysis, the degradation percentage of MO increases from 54% for bare CaTiO₃particles to 72% for CaTiO₃@Ag composites. This can be explained by the fact that photogenerated electrons are captured by Ag nanoparticles and photogenerated holes are therefore increasingly available to react with OH⁻/H₂O to generate hydroxyl (·OH) radicals. ·OH radicals were detected by fluorimetry using terephthalic acid as a probe molecule, revealing an enhanced yield on the irradiated CaTiO₃@Ag composites. In addition, it is found that the addition of ethanol, which acts as an ·OH scavenger, leads to a quenching of ·OH radicals and simultaneous decrease in the photocatalytic efficiency. This suggests that ·OH radicals are the dominant active species responsible for the dye degradation.
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