10,400 research outputs found
Some new class of Chaplygin Wormholes
Some new class of Chaplygin wormholes are investigated in the framework of a
Chaplygin gas with equation of state , . Since
empty spacetime () does not follow Chaplygin gas, so the
interior Chaplygin wormhole solutions will never asymptotically flat. For this
reason, we have to match our interior wormhole solution with an exterior vacuum
solution i.e. Schwarzschild solution at some junction interface, say .
We also discuss the total amount of matter characterized by Chaplygin gas that
supplies fuel to construct a wormhole.Comment: 14 pages, 12 figures, Accepted for publication in Mod.Phys.Lett.
Ab initio lattice dynamics and electron-phonon coupling of Bi(111)
We present a comprehensive ab initio study of structural, electronic, lattice
dynamical and electron-phonon coupling properties of the Bi(111) surface within
density functional perturbation theory. Relativistic corrections due to
spin-orbit coupling are consistently taken into account. As calculations are
carried out in a periodic slab geometry, special attention is given to the
convergence with respect to the slab thickness. Although the electronic
structure of Bi(111) thin films varies significantly with thickness, we found
that the lattice dynamics of Bi(111) is quite robust and appears converged
already for slabs as thin as 6 bilayers. Changes of interatomic couplings are
confined mostly to the first two bilayers, resulting in super-bulk modes with
frequencies higher than the optic bulk spectrum, and in an enhanced density of
states at lower frequencies for atoms in the first bilayer. Electronic states
of the surface band related to the outer part of the hole Fermi surfaces
exhibit a moderate electron-phonon coupling of about 0.45, which is larger than
the coupling constant of bulk Bi. States at the inner part of the hole surface
as well as those forming the electron pocket close to the zone center show much
increased couplings due to transitions into bulk projected states near
Gamma_bar. For these cases, the state dependent Eliashberg functions exhibit
pronounced peaks at low energy and strongly deviate in shape from a Debye-like
spectrum, indicating that an extraction of the coupling strength from measured
electronic self-energies based on this simple model is likely to fail.Comment: 30 pages, 11 figure
Oral cancer secretome: Identification of cancer-associated proteins
This study aims to identify cancer-associated proteins in the secretome of oral cancer cell lines. We have successfully established four primary cell cultures of normal cells with a limited lifespan without human telomerase reverse transcriptase (hTERT) immortalization. The secretome of these primary cell cultures were compared with that of oral cancer cell lines using 2DE. Thirty five protein spots were found to have changed in abundance. Unambiguous identification of these proteins was achieved by MALDI TOF/TOF. In silico analysis predicted that 24 of these proteins were secreted via classical or nonclassical mechanisms. The mRNA expression of six genes was found to correlate with the corresponding protein abundance. Ingenuity Pathway Analysis (IPA) core analysis revealed that the identified proteins were relevant in, and related to, cancer development with likely involvements in tumor growth, metastasis, hyperproliferation, tumorigenesis, neoplasia, hyperplasia, and cell transformation. In conclusion, we have demonstrated that a comparative study of the secretome of cancer versus normal cell lines can be used to identify cancer-associated proteins.Article Link: http://onlinelibrary.wiley.com/doi/10.1002/elps.201300126/abstrac
The q-harmonic oscillator and an analog of the Charlier polynomials
A model of a q-harmonic oscillator based on q-Charlier polynomials of
Al-Salam and Carlitz is discussed. Simple explicit realization of q-creation
and q-annihilation operators, q-coherent states and an analog of the Fourier
transformation are found. A connection of the kernel of this transform with
biorthogonal rational functions is observed
Enhancing the Stretchability of Two-Dimensional Materials through Kirigami: A Molecular Dynamics Study on Tungsten Disulfide
In recent years, the 'kirigami' technique has gained significant attention
for creating meta-structures and meta-materials with exceptional
characteristics, such as unprecedented stretchability. These properties, not
typically inherent in the original materials or structures, present new
opportunities for applications in stretchable electronics and photovoltaics.
However, despite its scientific and practical significance, the application of
kirigami patterning on a monolayer of tungsten disulfide (WS2), a van der Waals
material with exceptional mechanical, electronic, and optical properties, has
remained unexplored. This study utilizes molecular dynamics (MD) simulations to
investigate the mechanical properties of monolayer WS2 with rectangular
kirigami cuts. We find that, under tensile loading, the WS2 based kirigami
structure exhibits a notable increase in tensile strain and a decrease in
strength, thus demonstrating the effectiveness of the kirigami cutting
technique in enhancing the stretchability of monolayer WS2. Additionally,
increasing the overlap ratio enhances the stretchability of the structure,
allowing for tailored high strength or high strain requirements. Furthermore,
our observations reveal that increasing the density of cuts and reducing the
length-to-width ratio of the kirigami nanosheet further improve the fracture
strain, thereby enhancing the overall stretchability of the proposed kirigami
patterned structure of WS2.Comment: 19 pages, 5 figure
Low-Cost Aquifer Storage and Recovery: Implications for Improving Drinking Water Access for Rural Communities in Coastal Bangladesh
Fresh water resources are scarce in rural communities in the southern deltaic plains of Bangladesh where both shallow and deep groundwater is frequently brackish, and fresh water ponds have been increasingly salinized by inundation during storm surges and brackish-water aquaculture. Low-cost aquifer storage and recovery (ASR) schemes were constructed at 13 villages in three coastal districts by developing storage in shallow confined fine to medium sand aquifers overlain by variable thicknesses of silt and clay. A typical ASR scheme consisted of a double-chambered graded sand filtration tank with a volume of 19.5 m3 that feeds filtered pond water to four to six large diameter (d=30.5 or 56 cm) infiltration wells through PVC pipes fitted with stop valves and flow meters. The infiltration wells were completed at 18–31 m below ground and filled with well-sorted gravel capped with a thin layer of fine sand that acts as a second stage filter. Infiltration rates at 13 sites averaged 3 m3/day (range: 3–6 m3/day) over one year of operation. At 11 sites where water was abstracted, the recovery rate ranged from 5 to 40%. The source pond source water frequently had turbidity values of ≥100 NTU. After sand filtration, the turbidity is typically 5 NTU. Despite this, clogging management involving frequent (monthly to weekly) manual washing to remove fine materials deposited in the sand filtration tank and the infiltration wells is found to be necessary and effective, with post-manual-washing operational infiltration rates restored to annual average values. E. coli counts in recovered water are greatly reduced compared to raw pond water, although E. coli is still detected in about half of the samples. Arsenic in recovered water was detected to be at level of > 100 μg/L repeatedly at three sites, suggesting that As risks must be carefully managed and require further investigation
Bioactivity and In Silico Studies of Isoquinoline and Related Alkaloids as Promising Antiviral Agents: An Insight
Viruses are widely recognized as the primary cause of infectious diseases around the world. The ongoing global pandemic due to the emergence of SARS-CoV-2 further added fuel to the fire. The development of therapeutics becomes very difficult as viruses can mutate their genome to become more complex and resistant. Medicinal plants and phytocompounds could be alternative options. Isoquinoline and their related alkaloids are naturally occurring compounds that interfere with multiple pathways including nuclear factor-κB, mitogen-activated protein kinase/extracellular-signal-regulated kinase, and inhibition of Ca²⁺-mediated fusion. These pathways play a crucial role in viral replication. Thus, the major goal of this study is to comprehend the function of various isoquinoline and related alkaloids in viral infections by examining their potential mechanisms of action, structure-activity relationships (SAR), in silico (particularly for SARS-CoV-2), in vitro and in vivo studies. The current advancements in isoquinoline and related alkaloids as discussed in the present review could facilitate an in-depth understanding of their role in the drug discovery process
Free radical activity of industrial fibers: role of iron in oxidative stress and activation of transcription factors.
We studied asbestos, vitreous fiber (MMVF10), and refractory ceramic fiber (RCF1) from the Thermal Insulation Manufacturers' Association fiber repository regarding the following: free radical damage to plasmid DNA, iron release, ability to deplete glutathione (GSH), and activate redox-sensitive transcription factors in macrophages. Asbestos had much more free radical activity than any of the man-made vitreous fibers. More Fe3+ was released than Fe2+ and more of both was released at pH 4.5 than at pH 7.2. Release of iron from the different fibers was generally not a good correlate of ability to cause free radical injury to the plasmid DNA. All fiber types caused some degree of oxidative stress, as revealed by depletion of intracellular GSH. Amosite asbestos upregulated nuclear binding of activator protein 1 transcription factor to a greater level than MMVF10 and RCF1; long-fiber amosite was the only fiber to enhance activation of the transcription factor nuclear factor kappa B (NF kappa B). The use of cysteine methyl ester and buthionine sulfoximine to modulate GSH suggested that GSH homeostasis was important in leading to activation of transcription factors. We conclude that the intrinsic free radical activity is the major determinant of transcription factor activation and therefore gene expression in alveolar macrophages. Although this was not related to iron release or ability to deplete macrophage GSH at 4 hr, GSH does play a role in activation of NF kappa B
- …