A novel liquid chromatographic system which enables high temperature ultrafast liquid chromatography (HTU-FLC) has been designed through the careful consideration of heat transfer, band broadening, and pressure drop. Studies of the effect of linear velocity on the HETP show that column efficiency at high velocity, especially of well-retained solutes, dramatically improves at higher temperatures. At 150 degrees C, at a flow rate of 15 mL/min with a 5 cm by 4.6 mm (i.d.) column packed with 3 microns polystyrene-coated zirconia porous particles, long chain alkylphenones were completely resolved, and the analysis time could be decreased by a factor of 50 compared to that at room temperature (25 degrees C) at a conventional flow rate (4 mL/min). In addition, using pure water as the mobile phase, five phenols were separated in less than 30 s.

Review Practice and theory of high temperature liquid chromatographyHigh temperature liquid chromatography (HTLC) exists in a temperature region beyond ambient (ca. 408C) and below super critical temperatures. The promises of HTLC, such as increased analysis speed, enhanced separation productivity, "green" LC with pure water mobile phases coupled to universal FID detection, and fast analysis of complex samples by combination with fast 2-D techniques, have become an option for routine practice. The focus of this paper is to review the key developments that have made the application of HTLC a practical technique and draw attention to new developments in 2-D techniques that incorporate HTLC that offer an opportunity to vastly increase the usefulness of HPLC for the analysis of complex samples.

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Monodisperse, spherical, and nonporous zirconia particles ranging from submicrons to microns for use as supports for capillary electrophoresis and chromatography were synthesized by the controlled hydrolysis of zirconium tetra-alkoxides in alcohol solutions in the presence of long-chain organic acids. Particle characteristics varied as a function of water concentration, the chain length of the organic acid, aging time, temperature, and extent of stirring. Changing these experimental parameters affected particle size, particle size distribution, and the degree of particle aggregation. Submicron particles were made by increasing the water concentration and decreasing aging time. Particle size increases as temperature during the aging period increases. Most importantly, large monodisperse particles (4 lm) could be made by extended stirring. In general, we found that particle size increases as the chain length of the organic acid increases. We also found that gentle rotation during the aging period prevented both particle settling and secondary nucleation. This allowed the production of large particles. BET nitrogen adsorption uptake measurements demonstrate that the particles could be sintered, without aggregating them, to remove virtually all internal porosity. 707J ournal

Although it has been known for some time that monodisperse, micrometer-scale spherical zirconia particles can be synthesized by the hydrolysis of zirconium alkoxides, the particles so made are frequently aggregated. Moreover, it is not clear whether they can be made nonporous without suffering aggregation; this would limit their usefulness in applications like ultrafast chromatography, which require that the particles be spherical and unaggregated (which we term "microspheres") and that they be nonporous. Here we report that when using an alkoxide hydrolysis synthesis process, critical washing steps can eliminate irreversible aggregation and so enable reliable production of microspheres. We clarify important but practical precautions that easily ensure the reproducibility of the synthesis method. Finally, we demonstrate that the microspheres can be made nonporous with a suitable heating schedule.

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Modifications in land use patterns exert profound influences on the configuration, arrangement, and functioning of terrestrial ecosystems, thereby inducing fluctuations in carbon sequestration. Consequently, precise ecological decision-making and an in-depth exploration of the interplay between land use alterations and carbon storage dynamics assume paramount importance in the pursuit of optimal regional land use configurations. In this investigation, we employed the InVEST model to analyze the spatiotemporal variations in land utilization and carbon storage in Hunan Province, based on comprehensive land use data spanning the period from 2000 to 2020. Additionally, the PLUS model was utilized to project the future spatial distribution of carbon storage in Hunan Province until 2040, encompassing diverse development scenarios. The findings of our study are as follows: (1) Land use changes instantaneously impact carbon storage within the study area. From 2000 to 2020, urban construction land witnessed an expansion of 3542 km2, which accounted for an increase from 1.13% to 2.78% of the total land area. Consequently, there was a decline in arable land, woodlands, and grasslands, resulting in a reduction of 3430.25 tons of carbon storage in Hunan Province. (2) The ecological protection scenario is projected to yield the most substantial increase in carbon storage, with an estimated magnitude of 7.02 × 10⁶ tons by the year 2040. According to the natural evolution scenario, the total amount of carbon storage is anticipated to remain similar to that of 2020, with a marginal increase of 2.81 × 10⁵ tons. Under the arable land protection scenario, carbon storage is predicted to decrease by 1.060 × 10⁷ tons. Conversely, the urban development scenario is expected to result in the most substantial reduction of 2.243 × 10⁷ tons of carbon storage. These findings underscore the efficacy of adopting ecological protection and natural development policies in curbing the decline in carbon storage. (3) The geographic distribution of carbon storage areas exhibits a strong correspondence with that of land use. Regions characterized by elevated carbon storage levels exhibit minimal urban construction land, an abundance of compact and contiguous ecological land, and a higher frequency of such land parcels. To enhance regional carbon storage levels and achieve sustainable development goals, future endeavors should prioritize the implementation of ecological protection and natural development policies.