7,828 research outputs found
Biocatalysis as Useful Tool in Asymmetric Synthesis: An Assessment of Recently Granted Patents (2014–2019)
The broad interdisciplinary nature of biocatalysis fosters innovation, as different technical fields are interconnected and synergized. A way to depict that innovation is by conducting a survey on patent activities. This paper analyses the intellectual property activities of the last five years (2014–2019) with a specific focus on biocatalysis applied to asymmetric synthesis. Furthermore, to reflect the inventive and innovative steps, only patents that were granted during that period are considered. Patent searches using several keywords (e.g., enzyme names) have been conducted by using several patent engine servers (e.g., Espacenet, SciFinder, Google Patents), with focus on granted patents during the period 2014–2019. Around 200 granted patents have been identified, covering all enzyme types. The inventive pattern focuses on the protection of novel protein sequences, as well as on new substrates. In some other cases, combined processes, multi-step enzymatic reactions, as well as process conditions are the innovative basis. Both industries and academic groups are active in patenting. As a conclusion of this survey, we can assert that biocatalysis is increasingly recognized as a useful tool for asymmetric synthesis and being considered as an innovative option to build IP and protect synthetic routes
Renormings of
We investigate the best order of smoothness of . We prove in
particular that there exists a -smooth bump function on if
and only if and are both even integers and is a multiple of .Comment: 18 pages; AMS-Te
Gaussian to Exponential Crossover in the Attenuation of Polarization Echoes in NMR
An ingenious pulse sequence devised by S. Zhang, B. H. Meier, and R. R. Ernst
(Phys. Rev. Lett. {\bf 69}, 2149 (1992)) reverses the time evolution (``spin
diffusion'') of the local polarization in a dipolar coupled H spin
system. This refocusing originates a Polarization Echo whose amplitude
attenuates by increasing the time elapsed until the dynamics is reversed.
Different functional attenuations are found for a set of dipolar coupled
systems: ferrocene, (CH)Fe, cymantrene, (CH)Mn(CO), and
cobaltocene, (CH)Co. To control a relevant variable involved in
this attenuation a pulse sequence has been devised to progressively reduce the
dipolar dynamics. Since it reduces the evolution of the polarization echo it is
referred as REPE sequence. Two extreme behaviors were found while
characterizing the materials: In systems with a strong source of relaxation and
slow dynamics, the attenuation follows an exponential law (cymantrene). In
systems with a strong dipolar dynamics the attenuation is mainly Gaussian. By
the application of the REPE sequence the characteristic time of the Gaussian
decay is increased until the presence of an underlying dissipative mechanism is
revealed (cobaltocene). For ferrocene, however, the attenuation remains
Gaussian within the experimental time scale. These two behaviors suggest that
the many body quantum dynamics presents an extreme intrinsic instability which,
in the presence of small perturbations, leads to the onset of irreversibility.
This experimental conclusion is consistent with the tendencies displayed by the
numerical solutions of model systems.Comment: 7 pages + 7 Postscript figure
Autonomous thermal machine for amplification and control of energetic coherence
We present a model for an autonomous quantum thermal machine comprised of two
qubits capable of manipulating and even amplifying the local coherence in a
non-degenerate external system. The machine uses only thermal resources,
namely, contact with two heat baths at different temperatures, and the external
system has a non-zero initial amount of coherence. The method we propose allows
for an interconversion between energy, both work and heat, and coherence in an
autonomous configuration working in out-of-equilibrium conditions. This model
raises interesting questions about the role of fundamental limitations on
transformations involving coherence and opens up new possibilities in the
manipulation of coherence by autonomous thermal machines.Comment: v1: 5 + 3 pages, 2 figures. v2: Restructured version with several new
results and a new appendix, 11 + 14 pages, 4 + 3 figures. v3: Improved and
corrected version with new discussions, 8 + 8 pages, 4 + 3 figure
Nonequilibrium potential and fluctuation theorems for quantum maps
We derive a general fluctuation theorem for quantum maps. The theorem applies
to a broad class of quantum dynamics, such as unitary evolution, decoherence,
thermalization, and other types of evolution for quantum open systems. The
theorem reproduces well-known fluctuation theorems in a single and simplified
framework and extends the Hatano-Sasa theorem to quantum nonequilibrium
processes. Moreover, it helps to elucidate the physical nature of the
environment inducing a given dynamics in an open quantum system.Comment: 10 page
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