112 research outputs found
Holographic three flavor baryon in the Witten-Sakai-Sugimoto model with the D0-D4 background
With the construction of the Witten-Sakai-Sugimoto model in the D0-D4
background, we systematically investigate the holographic baryon spectrum in
the case of three flavors. The background geometry in this model is
holographically dual to Yang-Mills theory in large
limit involving an excited state with a nonzero angle or glue
condensate , which is proportional to the charge density of
the smeared D0-branes through a parameter or . The
classical solution of baryon in this model can be modified by embedding the
Belavin-Polyakov-Schwarz-Tyupkin (BPST) instanton and we carry out the
quantization of the collective modes with this solution. Then we extend the
analysis to include the heavy flavor and find that the heavy meson is always
bound in the form of the zero mode of the flavor instanton in strong coupling
limit. The mass spectrum of heavy-light baryons in the situation with single-
and double-heavy baryon is derived by solving the eigen equation of the
quantized collective Hamiltonian. Afterwards we obtain that the constraint of
stable baryon states has to be and the difference in the baryon
spectrum becomes smaller as the D0 charge increases. It indicates that quarks
or mesons can not form stable baryons if the angle or glue condensate
is sufficiently large. Our work is an extension of the previous study of this
model and also agrees with those conclusions.Comment: 35 pages, 2 figures, 1 table, this version includes the
acknowledgement and some revision
StoryDroid: Automated Generation of Storyboard for Android Apps
Mobile apps are now ubiquitous. Before developing a new app, the development
team usually endeavors painstaking efforts to review many existing apps with
similar purposes. The review process is crucial in the sense that it reduces
market risks and provides inspiration for app development. However, manual
exploration of hundreds of existing apps by different roles (e.g., product
manager, UI/UX designer, developer) in a development team can be ineffective.
For example, it is difficult to completely explore all the functionalities of
the app in a short period of time. Inspired by the conception of storyboard in
movie production, we propose a system, StoryDroid, to automatically generate
the storyboard for Android apps, and assist different roles to review apps
efficiently. Specifically, StoryDroid extracts the activity transition graph
and leverages static analysis techniques to render UI pages to visualize the
storyboard with the rendered pages. The mapping relations between UI pages and
the corresponding implementation code (e.g., layout code, activity code, and
method hierarchy) are also provided to users. Our comprehensive experiments
unveil that StoryDroid is effective and indeed useful to assist app
development. The outputs of StoryDroid enable several potential applications,
such as the recommendation of UI design and layout code
One-Step Preparation of High Performance TiO 2 /CNT/CQD Nanocomposites Bactericidal Coating with Ultrasonic Radiation
© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).As an environmental semiconductor material, TiO2 has important applications in the fields of environmental protection and water treatment. The preparation of P25 particles into nano-functional material films with a high specific surface area has always been a bottleneck limiting its large-scale application. In this paper, a one-step method of preparing TiO2 nanocomposites by doping carbon nanotube (CNT) and carbon quantum dots (CQD) with tetrabutyltitanate and P25 TiO2 under ultrasonic radiation is proposed to synthesize a novel antifouling material, which both eliminates the bacterium of Escherichia coli and shows good photoelectric properties, indicating a great value for the industrial promotion of TiO2/CNT. This mesoporous composite exhibits a high specific surface area of 78.07 M2/g (BET) and a tested pore width range within 10–120 nm. The surface morphology of this composite is characterized by TEM and the microstructure is characterized through XRD. This preparation method can fabricate P25 particles into a nano-functional material film with a high specific surface area at a very low cost.Peer reviewe
Pyruvate Kinase regulates the Pentose-Phosphate pathway in Response to Hypoxia in Mycobacterium tuberculosis
In response to the stress of infection, Mycobacterium tuberculosis (Mtb) reprograms its metabolism to accommodate nutrient and energetic demands in a changing environment. Pyruvate kinase (PYK) is an essential glycolytic enzyme in the phosphoenolpyruvate–pyruvate–oxaloacetate node that is a central switch point for carbon flux distribution. Here we show that the competitive binding of pentose monophosphate inhibitors or the activator glucose 6-phosphate (G6P) to MtbPYK tightly regulates the metabolic flux. Intriguingly, pentose monophosphates were found to share the same binding site with G6P. The determination of a crystal structure of MtbPYK with bound ribose 5-phosphate (R5P), combined with biochemical analyses and molecular dynamic simulations, revealed that the allosteric inhibitor pentose monophosphate increases PYK structural dynamics, weakens the structural network communication, and impairs substrate binding. G6P, on the other hand, primes and activates the tetramer by decreasing protein flexibility and strengthening allosteric coupling. Therefore, we propose that MtbPYK uses these differences in conformational dynamics to up- and down-regulate enzymic activity. Importantly, metabolome profiling in mycobacteria reveals a significant increase in the levels of pentose monophosphate during hypoxia, which provides insights into how PYK uses dynamics of the tetramer as a competitive allosteric mechanism to retard glycolysis and facilitate metabolic reprogramming toward the pentose-phosphate pathway for achieving redox balance and an anticipatory metabolic response in Mtb
Nomenclatural and taxonomic notes on Rubus davidianus Kuntze and R. viburnifolius Franch
Critical examinations of specimens, with literature reviews, have shown that Rubus davidianus is conspecific with R. lambertianus. Therefore, we treat R. davidianus as a new synonym within Rubus. We propose a new name, Rubus loirensis Ti R. Huang nom. nov. to replace the later homonym of R. pycnanthus Genev. Additionally, lectotypification of three names, R. davidianus Kuntze, R. malifolius Focke and R. viburnifolius Franch., are designated here after examination of previous works
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