The growth of metal oxide nanocrystals with a well-organized crystalline phase is of fundamental and technological interest because in this way it is possible to tune their size-dependent unique ...properties. In this communication, we demonstrate the selective growth of monoclinic and tetragonal ZrO2 nanocrystals of <10 nm diameter driven by controlling the surface energy, with and without capping by N(CH3)4 +. The nanocrystals were grown in aqueous solution at 150 °C. It was revealed, by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and optical absorption studies, that the nanocrystals capped by N(CH3)4 + have a less defective pure monoclinic phase, while those without capping have a pure tetragonal phase with highly disordered oxygen vacancies. The N(CH3)4 + capping on the surface oxygen site can reduce the surface energy low enough to stabilize the monoclinic phase. By contrast, the bare surface oxygen site has higher energy; thereby, the lower surface energy tetragonal phase is formed spontaneously. The present concept is a promising universal approach to control the crystal phases of technologically important oxide nanocrystals
TiO2 nanosheets have been studied as photocatalysts in various fields, and their performance has been actively improved. Herein, we prepared titania nanosheets with a smaller size than those reported ...previously with a side length of 29 nm and investigated their photocatalytic activity. (NH4)2TiF6 and Ti(OBu)4 were used as raw materials, and the F/Ti ratio was varied in the range of 0.3 to 2.0 to produce a series of samples with different side lengths by hydrothermal synthesis. A reduction in the F/Ti ratio led to the reduced size of the titanium nanosheets. The photocatalytic activity of each sample was evaluated through the degradation of methylene blue (MB) under ultraviolet (UV) irradiation (365 nm, 2.5 mW/cm2). UV irradiation promoted the decomposition of MB, and the highest degradation efficiency was achieved using titania nanosheets prepared with a F/Ti ratio of 0.3. The high catalytic activity can be attributed to the increase in the surface area due to size reduction. The ratio of the {001} surface exposed on the titania nanosheet also affected the photocatalytic activity; it resulted in increased activation of the reaction. This study demonstrates that further activation of the photocatalytic activity can be achieved by adjusting the size of titania nanosheets.
The demand for resource circulation of heat exchangers in air conditioners is expected to grow rapidly; however, the market stocking time is relatively long. Therefore, this scenario was used as a ...case study for sustainable products design. A material flow analysis was conducted to estimate the balance between global relative resource consumption for shipment, waste, and installed stock from publicly available information up to 2050. Based on the projected demand through 2050, the shipment volume for each year was calculated on a cooling capacity basis. From this analysis, the waste volume was calculated. Using the shipment volume on the basis of yearly cooling capacity, the shipment volume on a resource basis was calculated considering the heat transfer coefficient. The balance between the waste volume and the installed stock was estimated. The resource circulation was simulated by defining variables such as the ratio of units that can be converted from waste to shipment and the ratio of heat exchangers using circulated resources in the total number of shipments. The results indicate that the shipment, waste, and installed stock of resources projected for 2050 were greater than those at the 2021 levels by factors of 2.2, 2.8, and 2.9, respectively. In addition, they were greater than those of the 2021 levels in the scenarios by factors of 1.8, 2.2, and 2.8 accounting for the increase of heat transfer coefficient into account, indicating the importance of improvement of heat transfer. The simulation of circulation showed that a fully closed loop in 2050 would be difficult to achieve owing to the shortage of heat exchangers for waste-to-shipment. Sensitivity analysis also indicated that even under conditions where there is no predicted shortage of circulated resources for 2050, achieving the target in a short period of time may cause a rapid increase in demand for circulating resources. This would subsequently, lead to a shortage of supply compared to demand. Thus, it is important to account for these dynamics relating resource circulation and strategy planning during analysis.
This study investigated the effect of single-boiling crystallization of high-yielding sugarcane on sugar and molasses production on a factory-plant scale compared with triple-boiling crystallization ...of conventional sugarcane. The sugar extraction at the roll-milling process was similar between high-yielding sugarcane KY01-2044 with high fiber and conventional sugarcane NiF8. The weight of sugar yield per sugarcane decreased by 32.6 % compared with the conventional system, whereas the yield of molasses and bagasse increased by 143.1 % and 11.5 %, respectively. The results indicated that sugar, molasses, and bagasse-derived electricity could increase simultaneously when the yields of high-yielding sugarcane were higher by a factor of 1.5 than conventional levels. Furthermore, A-molasses obtained by a single-boiling crystallization had less coloration and better fermentability and operability than conventional C-molasses. In conclusion, this study showed that combining high-yielding sugarcane and single-boiling crystallization could increase sugar production and generate high-quality molasses suitable for biofuel and bagasse-derived electricity production.
We compare the Raman scattering properties of hybrid nanostructures consisting of Ag nanoparticles (NPs) in disordered and aligned arrangements on single-walled carbon nanotubes (SWCNTs) as a result ...of chemical and photoreduction methods. In the latter case, the unique structure of the very small Ag NP (from 4 to 7 nm) chains generated an extremely large mode at 969 cm(-1) that was assigned to the sulphate-silver interaction at the NP surface. Another strong mode was present at 1201 cm(-1) and was assigned to an IR-active mode of sodium dodecyl sulphate (SDS); this mode was observed because the symmetry changes altered the selection rules. We demonstrate that both the UV photoreduction of silver and the presence of SWCNTs are necessary to produce this very strong Raman scattering. The Raman modes of the SWCNTs are also significantly modified by the presence of Ag NP chains along the nanotubes.
A core-shell anode consisting of nickel-gadolinium-doped-ceria (Ni-GDC) nanocubes was directly fabricated by a chemical process in a solution containing a nickel source and GDC nanocubes covered with ...highly reactive {001} facets. The cermet anode effectively generated a Ni metal framework even at 500 °C with the growth of the Ni spheres. Anode fabrication at such a low temperature without any sintering could insert a finely nanostructured layer close to the interface between the electrolyte and the anode. The maximum power density of the attractive anode was 97 mW cm(-2), which is higher than that of a conventional NiO-GDC anode prepared by an aerosol process at 55 mW cm(-2) and 600 °C, followed by sintering at 1300 °C. Furthermore, the macro- and microstructure of the Ni-GDC-nanocube anode were preserved before and after the power-generation test at 700 °C. Especially, the reactive {001} facets were stabled even after generation test, which served to reduce the activation energy for fuel oxidation successfully.
Ilmenite, FeTiO
, is a common mineral in nature, existing as an accessory phase in the most basic igneous and metamorphic rocks, for example, it is derived from the upper mantle. Therefore, an ...understanding of the high-pressure physics of FeTiO
is of fundamental importance in the study of rock magnetization. Here, we provide experimental evidence of lattice compression of FeTiO
powder using super-high-energy ball milling, enabling the very high collision energy of 420 times gravitational acceleration. A sample obtained as an ilmenite- hematite 0.5FeTiO
·0.5Fe
O
solid solution showed a decrease in molar volume of approximately 1.8%. Consequently, the oxidation state in FeTiO
powder was changed into almost Fe
Ti
, corresponding to 87% Fe
of the total Fe for FeTiO
, resulting in the emergence of ferromagnetism. This new ferromagnetic behaviour is of crucial importance in the study of rock magnetization which is used to interpret historical fluctuations in geomagnetism. In addition, the super-high-energy ball mill can be used to control a range of charge and spin states in transition metal oxides with high pressure.
Titania (TiO2) has attracted much attention recently for reducing bacterial diseases by the generation of reactive oxygen species (ROS) under UV irradiation. However, demand for higher photocatalytic ...activity due to higher recombination of electron and hole remains. The aims of this study were to make titania with higher antibacterial property and show the mechanisms of the bactericidal effect. In this study, we hydrothermally synthesized TiO2 nanosheets (NS) with highly-oriented structures. Samples were divided into five groups, depending on the fluorine/titanium ratio in the raw material, namely NS1.0, NS1.2, NS1.5, NS1.8, and NS2.0. Facet ratio and nanosheet size increased with an increase of fluorine/titanium ratio. The photocatalytic activity of TiO2 nanosheet was assessed by the generation of ROS. Hydroxyl radicals and superoxides were generated efficiently by ultraviolet light irradiation on NS1.5 and NS1.0, respectively. Antibacterial activity against Streptococcus mutans was assessed in the presence and absence of UV irradiation; NS1.0 showed superior antibacterial properties compared to commercially available TiO2 nanoparticles, under both conditions, due to the oxidation of intracellular components and cell membrane. These results together suggested TiO2 nanosheet induced bacterial cell death by oxidation, and TiO2 facet engineering resulted in enhancement of both photocatalytic and antibacterial activities of TiO2.
Colloidal cerium oxide (CeO2) nanocrystals prepared by hydrothermal synthesis were characterized by high-resolution transmission electron microscopy (HRTEM) and three-dimensional electron tomography ...(3D-ET). HRTEM images of individual CeO2 nanocrystals were then simulated by Blochwave and multislice simulations to determine the atomic arrangement and terminating atoms. The edge length distributions were between 5.0 and 8.0 nm with an average edge length of 6.7 nm. The HRTEM images showed that the CeO2 particles were slightly truncated revealing {220} facets. 3D-ET revealed that the CeO2 nanocrystals exposed predominantly {200} cubic facets. The nanocrystals were truncated at the corners exposing {111} octahedral facets and at the edges {220} dodecahedral facets. Furthermore, 3D-ET revealed the presence of some tetragonal-shaped CeO2 nanocrystals.
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