141 research outputs found
Synthesis and Biological Evaluation of Ezetimibe Analogs as Possible Cholesterol Absorption Inhibitors
In order to investigate the SAR of Ezetimibe analogs for cholesterol absorption inhibitions, amide group and electron-deficient pyridine ring were introduced to the C-(3) carbon chain of Ezetimibe. Eight new derivatives of the 2-azetidinone cholesterol absorption inhibitors have been synthesized, and all of them were enantiomerically pure. All the new compounds were evaluated for their activity to inhibit cholesterol absorption in hamsters, and most of them showed comparable effects in lowering the levels of total cholesterol in the serum
Patterns and driving forces of dimensionality-dependent charge density waves in 2H-type transition metal dichalcogenides
Two-dimensional (2D) materials have become a fertile playground for the
exploration and manipulation of novel collective electronic states. Recent
experiments have unveiled a variety of robust 2D orders in highly-crystalline
materials ranging from magnetism to ferroelectricity and from superconductivity
to charge density wave (CDW) instability. The latter, in particular, appears in
diverse patterns even within the same family of materials with isoelectronic
species. Furthermore, how they evolve with dimensionality has so far remained
elusive. Here we propose a general framework that provides a unfied picture of
CDW ordering in the 2H polytype of four isoelectronic transition metal
dichalcogenides 2H-MX (M=Nb, Ta and X=S, Se). We first show experimentally
that whilst NbSe exhibits a strongly enhanced CDW order in the 2D limit,
the opposite trend exists for TaSe and TaS, with CDW being entirely
absent in NbS from its bulk to the monolayer. Such distinct behaviours are
then demonstrated to be the result of a subtle, yet profound, competition
between three factors: ionic charge transfer, electron-phonon coupling, and the
spreading extension of the electronic wave functions. Despite its simplicity,
our approach can, in essence, be applied to other quasi-2D materials to account
for their CDW response at different thicknesses, thereby shedding new light on
this intriguing quantum phenomenon and its underlying mechanisms
Sintering of Iron Ores in a Millipot in Comparison with Tablet Testing and Industrial Process
To explore the feasibility of small-scale sintering pot testing, a \u27millipot\u27 facility (diameter of 53 mm and height of 400 mm) was established and used to examine the sintering performance of iron ores and other non-traditional ferrous materials. The sintering performance of a millipot was examined across a range of different operational conditions (coke rate and suction pressure) and compared with an industrial sinter strand operation. Tablet tests were also performed to assist in the design of the millipot experiments and identify conditions for achieving mineral composition similar to the industrial sinter. For the millipot experiments, the materials used need to be compacted to increase the bulk density, and a higher coke rate is required to compensate the high heat loss caused by wall effects. A higher suction pressure is also necessary to maintain an oxidizing atmosphere in the sinter bed. As expected, it was not possible to eliminate the wall effect, which resulted in more primary hematite at edges of the sintered column. However, the sintered material from the center of column simulates industrial sinter reasonably well. As such, millipot provides a practical way to evaluate the sintering process and material performance at laboratory scale, helping to bridge the gap between tablet sintering and large scale pot sintering, or full scale plant trial. The results of millipot testing can be used for designing larger scale experiments or commercial sintering trials
The continuing evolution of Energy Policy
As the world confronts the Covid-19 pandemic, we hope that all of you are doing well. We know that many lives have been greatly disrupted, and that world economic activity is slowing and maybe declining in some places. We have read reports that energy consumption has been greatly affected by the slowdown in world economic activity—likely contributing to the sharp plunge in oil prices earlier this year. We do not know how long this pandemic may last. As we look forward to the end of the pandemic and a recovering world economy, however, we wonder if and how energy systems may have to be transformed, and whether new energy policy needs and approaches will emerge. Will we see any change in the trajectory of adopting sustainable energy systems and reducing carbon emissions?In the academic world, many of us are now teleworking and teaching our courses online. This transition has proved time consuming—so we want to thank our many reviewers who are staying on or close to schedule. So far, Energy Policy has been mostly unaffected by the pandemic, but we must recognize that the Elsevier employees who are responsible for the operations side of the journal may at some time be affected by Covid-19.In the meantime, we want to keep you informed about some recent developments regarding Energy Policy, including a little about its history and our editorial priorities
Negative flat band magnetism in a spin-orbit coupled correlated kagome magnet
It has long been speculated that electronic flat band systems can be a
fertile ground for hosting novel emergent phenomena including unconventional
magnetism and superconductivity. Although flat bands are known to exist in a
few systems such as heavy fermion materials and twisted bilayer graphene, their
microscopic roles and underlying mechanisms in generating emergent behavior
remain elusive. Here we use scanning tunneling microscopy to elucidate the
atomically resolved electronic states and their magnetic response in the kagome
magnet Co3Sn2S2. We observe a pronounced peak at the Fermi level, which is
identified to arise from the kinetically frustrated kagome flat band.
Increasing magnetic field up to +-8T, this state exhibits an anomalous
magnetization-polarized Zeeman shift, dominated by an orbital moment in
opposite to the field direction. Such negative magnetism can be understood as
spin-orbit coupling induced quantum phase effects tied to non-trivial flat band
systems. We image the flat band peak, resolve the associated negative
magnetism, and provide its connection to the Berry curvature field, showing
that Co3Sn2S2 is a rare example of kagome magnet where the low energy physics
can be dominated by the spin-orbit coupled flat band. Our methodology of
probing band-resolved ordering phenomena such as spin-orbit magnetism can also
be applied in future experiments to elucidate other exotic phenomena including
flat band superconductivity and anomalous quantum transport.Comment: Nature Physics onlin
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