Extra Rings Research Articles

Effects of torsion charge on optical appearance and additional photon rings of an asymmetric thin-shell wormhole

In this paper, we study the optical properties of asymmetric thin-shell wormholes (ATWs) under torsion charge. Utilizing the cut-and-paste method developed by Visser, we construct these wormholes and determine their key physical properties, such as the radius of the photon sphere and critical impact parameters, under different torsion charges. Furthermore, we investigate the effective potential and behavior of photon motion within the wormhole spacetime, identifying a relationship between photon trajectories and impact parameters. The study focuses on scenarios where thin accretion disks act as the primary light source. It reveals that the optical features of ATWs under torsion charge significantly differ from those of black holes (BHs). Notably, an increase in torsion charge leads to a reduction in the sizes of both extra photon rings and lensing bands, which serve as important markers for distinguishing and characterizing ATW spacetimes from those of BHs.

Observational appearance and extra photon rings of an asymmetric thin-shell wormhole with a Bardeen profile* *Supported by the National Natural Science Foundation of China (11903025), the Science and Technology Program of Sichuan Province, China(2023ZYD0023), and the starting fund of China West Normal University (18Q062)

In this work, the optical appearance of an asymmetric thin-shell wormhole with a Bardeen profile is studied. To initiate the process, we need to construct an asymmetric thin-shell wormhole utilizing the cut-and-paste technique proposed by Visser and subsequently ascertain its pertinent physical quantities such as the radius of the photon sphere and critical impact parameters for different values of magnetic charge g. Then, the effective potential and motion behavior of photons are also investigated within the framework of asymmetric thin-shell wormholes with a Bardeen profile. It can be found that the effective potential, ray trajectory, and azimuthal angle of the thin-shell wormhole exhibit a strong correlation with the mass ratio of black holes. By considering the accretion disk as the sole background light source, we observe additional photon rings and lensing bands in the optical appearance of the asymmetric thin-shell wormhole with a Bardeen profile compared to those exhibited by the Bardeen black hole. One can find that there is an increase in the size of the specific additional light bands with increasing magnetic charge g, which is different from the black hole case. These exceptionally luminous rings can serve as a robust criterion for the identification and characterization of the thin-shell wormhole spacetime.

The nonlinear optical properties and noncovalent interactions of supramolecular Donor−acceptor−donor assemblies between molecular tweezers and fullerenes

The supramolecular donor−acceptor−donor (D−A−D) system were formed between the tweezer and C60 with strong intermolecular charge transfer interactions, which enhance the two-photon absorption (TPA) cross-section. Here, we would use density functional theory method to investigate three effects of molecular structures on the intermolecular interactions and the second order NLO properties of supramolecular complexes, including: (1) the effects of N atom substitution in tweezer (2) the effects of four extra benzene rings in tweezer (3) the effect of fullerene size. It was found that the substitution of N atoms and the addition of the four extra benzene rings to tweezer weakened the intermolecule interactions between fullerene and tweezer, suggesting that they did not enhance the electron-giving capacities of tweezers. While the fullerenes of larger size can form the stronger intermolecule interaction with tweezers.

Simulation study of a coincidence detection system for non-invasive determination of arterial blood time-activity curve measurements

BackgroundArterial sampling in PET studies for the purposes of kinetic modeling remains an invasive, time-intensive, and expensive procedure. Alternatives to derive the blood time-activity curve (BTAC) non-invasively are either reliant on large vessels in the field of view or are laborious to implement and analyze as well as being prone to many processing errors. An alternative method is proposed in this work by the simulation of a non-invasive coincidence detection unit.ResultsWe utilized GATE simulations of a human forearm phantom with a blood flow model, as well as a model for dynamic radioactive bolus activity concentration based on clinical measurements. A fixed configuration of 14 and, also separately, 8 detectors were employed around the phantom, and simulations were performed to investigate signal detection parameters. Bismuth germanate (BGO) crystals proved to show the highest count rate capability and sensitivity to a simulated BTAC with a maximum coincidence rate of 575 cps. Repeatable location of the blood vessels in the forearm allowed a half-ring design with only 8 detectors. Using this configuration, maximum coincident rates of 250 cps and 42 cps were achieved with simulation of activity concentration determined from 15O and 18F arterial blood sampling. NECR simulated in a water phantom at 3 different vertical positions inside the 8-detector system (Y = − 1 cm, Y = − 2 cm, and Y = −3 cm) was 8360 cps, 13,041 cps, and 20,476 cps at an activity of 3.5 MBq. Addition of extra axial detection rings to the half-ring configuration provided increases in system sensitivity by a factor of approximately 10.ConclusionsInitial simulations demonstrated that the configuration of a single half-ring 8 detector of monolithic BGO crystals could describe the simulated BTAC in a clinically relevant forearm phantom with good signal properties, and an increased number of axial detection rings can provide increased sensitivity of the system. The system would find use in the derivation of the BTAC for use in the application of kinetic models without physical arterial sampling or reliance on image-based techniques.

Scaffold Simplification Strategy Leads to a Novel Generation of Dual Human Immunodeficiency Virus and Enterovirus-A71 Entry Inhibitors.

Currently, there are only three FDA-approved drugs that inhibit human immunodeficiency virus (HIV) entry-fusion into host cells. The situation is even worse for enterovirus EV71 infection for which no antiviral therapies are available. We describe here the discovery of potent entry dual inhibitors of HIV and EV71. These compounds contain in their structure three or four tryptophan (Trp) residues linked to a central scaffold. Critical for anti-HIV/EV71 activity is the presence of extra phenyl rings, bearing one or two carboxylates, at the C2 position of the indole ring of each Trp residue. The most potent derivatives, 22 and 30, inhibit early steps of the replicative cycles of HIV-1 and EV-A71 by interacting with their respective viral surfaces (glycoprotein gp120 of HIV and the fivefold axis of the EV-A71 capsid). The high potency, low toxicity, facile chemical synthesis, and great opportunities for chemical optimization make them useful prototypes for future medicinal chemistry studies.

Synthesis, Structural Characterization and Docking Studies of Sulfamoyl- Phenyl Acid Esters as Dipeptidyl Peptidase-IV Inhibitors.

Diabetes mellitus is a major worldwide health concern that has several serious complications including retinopathy, neuropathy, nephropathy and macrovascular diseases. Dipeptidyl peptidase-IV (DPP-IV) inhibitors, gliptins, are a new class of antidiabetic agents that potentiate the action of incretins in decreasing the blood glucose levels. In the present study, synthesis and characterization of a series of ten N4-sulfonamido-acrylic and phthalamic acid methyl esters (3a-e and 5a-e) were achieved. In vitro anti-DPP-IV activity of the synthesized compounds was evaluated, where compound 3b demonstrated the best activity with a % inhibition of 41.7 at 10 µM concentration and an IC50 of 23.9 µM. Moreover, Glide docking experiments revealed that our targeted compounds accommodate the binding site of DPP-IV and tend to form H-bonding with the backbones of R125, E206, S209, D545, K554, W629, Y631, and G632. Modeling findings recommend the attachment of bulky hydrophobic group on the ester side of the structure in addition to harboring extra aromatic rings that might be beneficial for better binding interaction and biological activity.

Efficient Small Molecule Organic Dyes Containing Different Bridges in Donor Moieties for Dye-Sensitized Solar Cells

Small molecule (molecular weight is around 500Da) organic dyes were synthesized and used as sensitizers for the dye-sensitized solar cells (DSSCs). The optical and electrochemical properties, theoretical studies and photovoltaic parameters of DSSCs baseed on these dyes were systematically investigated. In order to extend the conjugation extent, two extra phenyl units were attached to triphenylamine (TPA) units bridged with single bonds, double bonds or triple bonds, respectively. The DSSCs based on FWDS exhibited well performances: the short-circuit current density (Jsc) of 10.04, 10.91 and 9.12mAcm−2, respectively; the open circuit voltage (Voc) of 0.77, 0.75 and 0.78V, respectively; the power conversion efficiency (η) of 5.65%, 6.04% and 5.19%, respectively. Two extra phenyl units attached via double or triple bonds increase the planar nature of these molecules, increasing the loading amount, which ultimately can correlate into the received efficiency. The results indicated that it is an effective way to get efficient dyes by introducing extra phenyl rings into donor moiety especially adopting double bonds as the bridge. Finally, efficient DSSCs were achieved by using small molecule TPA-type dyes FWD1, FWD2 and FWD3 as the sensitizers.

Non-perturbative measurement of low-intensity charged particle beams

Non-perturbative measurements of low-intensity charged particle beams are particularly challenging to beam diagnostics due to the low amplitude of the induced electromagnetic fields. In the low-energy antiproton decelerator (AD) and the future extra low energy antiproton rings at CERN, an absolute measurement of the beam intensity is essential to monitor the operation efficiency. Superconducting quantum interference device (SQUID) based cryogenic current comparators (CCC) have been used for measuring slow charged beams in the nA range, showing a very good current resolution. But these were unable to measure fast bunched beams, due to the slew-rate limitation of SQUID devices and presented a strong susceptibility to external perturbations. Here, we present a CCC system developed for the AD machine, which was optimised in terms of its current resolution, system stability, ability to cope with short bunched beams, and immunity to mechanical vibrations. This paper presents the monitor design and the first results from measurements with a low energy antiproton beam obtained in the AD in 2015. These are the first CCC beam current measurements ever performed in a synchrotron machine with both coasting and short bunched beams. It is shown that the system is able to stably measure the AD beam throughout the entire cycle, with a current resolution of .

Enhancement of photodynamic therapy effects with mitochondrial reactive oxygen species

Enhancement of photodynamic therapy effects with mitochondrial reactive oxygen species

Synthesis and characterization of novel symmetrical and asymmetrical carboxyphthalocyanines with potential application in photodynamic therapy

Synthesis and characterization of novel symmetrical and asymmetrical carboxyphthalocyanines with potential application in photodynamic therapy

Circular Photonic Crystal Fibers: Numerical Analysis of Chromatic Dispersion and Losses

Detailed numerical analysis for dispersion properties and losses has been carried out for a new type of Photonic crystal fiber where the air-holes are arranged in a circular pattern with a silica matrix called as Circular Photonic Crystal Fiber (C-PCF). The dependence of different PCF geometrical parameters namely different circular spacings, air-hole diameter and numbers of air-hole rings are carried out in detail towards practical applications. Our numerical analysis establishes that total dispersion is strongly affected by the interplay between material dispersion and waveguide dispersion. For smaller air-filing fraction, adding extra air-hole rings does not change dispersion much whereas for higher air-filling fraction, the dispersion nature changes significantly. With proper adjustment of the parameters ultra-flattened dispersion could be achieved; though the application can be limited by higher losses. However, the ultra-flat dispersion fibers can be used for practical high power applications like supercontinuum generation (SCG) by reducing the loss at the pumping wavelength by increasing the no of air-hole rings. Broadband smooth SCG can also be achieved with low loss oscillating near-zero dispersion fiber with higher no of air-hole rings. The detail study shows that for realistic dispersion engineering we need to be careful for both loss and dispersion.

Suitability of scoring PCC rings and fragments for dose assessment after high-dose exposures to ionizing radiation

Assessment of radiation doses through measurement of dicentric chromosomes may be difficult due to the inability of damaged cells to reach mitosis. After high-dose exposures, premature chromosome condensation (PCC) has become an important method in biodosimetry. PCC can be induced upon fusion with mitotic cells, or by treatment with chemicals such as calyculin A or okadaic acid. Several different cytogenetic endpoints have been measured with chemically induced PCC, e.g., via scoring of extra chromosome pieces or ring chromosomes. The dose–effect curves published with chemically induced PCC show differences in their coefficients and in the distribution of rings among cells. Here we present a study with calyculin A to induce PCC in peripheral blood lymphocytes irradiated at nine different doses of γ-rays up to 20Gy. Colcemid was also added in order to observe metaphase cells. During microscopical analysis the chromosome aberrations observed in the different cell-cycle phases (G2/M-PCC, M/A-PCC and M cells) were recorded. The proportion of G2/M-PCC cells was predominant from 3 to 20Gy, M cells decreased above 1Gy and M/A-PCC cells remained constant at all doses and showed the highest frequencies of PCC rings. Depending on the cell-cycle phase there was a difference in the linear coefficients in the dose–effect curves of extra fragments and rings. Poisson distribution among PCC rings was observed after calyculin A+colcemid treatment, facilitating the use of this methodology also for partial body exposures to high doses. This has been tested with two simulated partial exposures to 6 and 12Gy. The estimated doses in the irradiated fraction were very close to the real dose, indicating the usefulness of this methodology.

Coupling of septins to the axial landmark by Bud4 in budding yeast

Cells of the budding yeast Saccharomyces cerevisiae select a site for polarized growth in a specific pattern that depends on their cell type. Haploid a and α cells bud in the axial budding pattern, which requires assembly of a landmark that includes the Bud4 protein. To understand how an axial bud site is established, we performed a structure-function analysis of Bud4. Bud4 contains DUF1709 (domain of unknown function), which is similar to a part of the anillin-homology domain, and a putative Pleckstrin homology (PH) domain near to its C terminus. Although its localization depends on septins, a conserved family of GTP-binding proteins, Bud4 is necessary for the stable inheritance of septin rings during cell division. Although some anillins interact directly with septins, we find that neither DUF1709 nor the PH domain is necessary for targeting Bud4 to the mother-bud neck. Instead, this C-terminal region is crucial for association of Bud4 with Bud3 and other components of the axial landmark. Remarkably, septins colocalize with Bud4 mutant proteins that lack these C-terminal domains, forming an arc or a single ring instead of a double ring during and after cytokinesis. Interestingly, overexpression of Bud4 also induces formation of extra Bud4 rings and arcs that are associated with septins. Analyses of a series of bud4 truncation mutants suggest that at least two domains in the central region play a redundant role in targeting Bud4 to the mother-bud neck and are thus likely to interact with septins. Taken together, these results indicate that Bud4 functions as a platform that links septins to the axial landmark.

Wireless Power Transmission between Two Metamaterial-Inspired Loops at 300 MHz

Based on a provided closed-form wireless power transmission (WPT) efficiency formula, which may be used for any value of load, we have analyzed the WPT efficiencies between two metamaterial-inspired loop antennas in various aspects. Due to the modeling based on low frequency circuit theory, the provided formula at the center resonant frequency has been found to be accurate until when the distance between the two loop antennas increases to 15 cm (about λ0/6 at 300 MHz). When the two loops get closer, the resonant frequency has been found to split into two in theory, simulations, and measurements. The EM-simulated and measured efficiencies at new resonant frequencies are 60.9 % and 46.3 %, respectively, at d=15 cm. With two extra rings around the loops, the maximum efficiency is enhanced to 93.7 % at d=15 cm. The effect of the additional two rings is about 30 %.

The Division Inhibitor EzrA Contains a Seven-Residue Patch Required for Maintaining the Dynamic Nature of the Medial FtsZ Ring

The essential cytoskeletal protein FtsZ assembles into a ring-like structure at the nascent division site and serves as a scaffold for the assembly of the prokaryotic division machinery. We previously characterized EzrA as an inhibitor of FtsZ assembly in Bacillus subtilis. EzrA interacts directly with FtsZ to prevent aberrant FtsZ assembly and cytokinesis at cell poles. EzrA also concentrates at the cytokinetic ring in an FtsZ-dependent manner, although its precise role at this position is not known. Here, we identified a conserved patch of amino acids in the EzrA C terminus that is essential for localization to the FtsZ ring. Mutations in this patch (designated the "QNR patch") abolish EzrA localization to midcell but do not significantly affect EzrA's ability to inhibit FtsZ assembly at cell poles. ezrA QNR patch mutant cells exhibit stabilized FtsZ assembly at midcell and are significantly longer than wild-type cells, despite lacking extra FtsZ rings. These results indicate that EzrA has two distinct activities in vivo: (i) preventing aberrant FtsZ ring formation at cell poles through inhibition of de novo FtsZ assembly and (ii) maintaining proper FtsZ assembly dynamics within the medial FtsZ ring, thereby rendering it sensitive to the factors responsible for coordinating cell growth and cell division.

A broader take on DNA

Slipping in extra benzene rings creates a broader DNA double helix that is similar to, but different from, natural DNA. Importantly, it can encode more genetic information — and that could have wide implications.

Glory phenomenon informs of presence and phase state of liquid water in cold clouds

Although the optical phenomenon of glory on cloud tops with negative temperatures is now widely known to be observable from aircraft, the information thereby obtained on cloud microphysics remains not called for. The analysis made in the present work is based on a comparison between the features of the glory phenomenon, geometric theory of bow formation, and Mie scattering theory. The convincing evidence has been provided that this sort of glory forms as a first-order bow from spherical particles with a refractive index of 1.81–1.82 and diameter over 20 μm. Thus obtained are solutions of two interrelated problems: (i) the cold-cloud glory is proved to be a bow formed from spheres with those unusual optical properties, (ii) once more corroboration is gained of earlier discovered existence in cold clouds of droplets of liquid water in specific phase state referred to amorphous water, or A-water. Physico-chemical and genetic peculiarities of A-water are briefly summarized here. The results obtained show that a detailed study and monitoring of the glory phenomenon are of great interest since the occurrences of the phenomenon itself as well as its geometrical and photo-chromatic characteristics provide unique remote information about the disperse phases of cold clouds. The visible size of the glory can serve as an indicator of the maximum size of A-water droplets, and its extra outer rings must reveal the presence of some forms of ice crystals.

SYNTHESIS OF CONFORMATIONALLY RESTRICTED NUCLEIC ACID FRAGMENTS USING RING-CLOSING ALKENE AND ENYNE METATHESIS REACTIONS

In the aim of constructing conformationally restricted nucleic acid fragments for the recognition of secondary RNA structures, we have synthesized different mono- and dinucleotides containing extra rings. These rings were prepared by ring-closing alkene or enyne metathesis reactions from nucleotide substrates in which double or triple bonds have been introduced.

An efficient design for birdcage probes dedicated to small-animal imaging experiments

We are presenting, in this paper, a simple, easily reproducible and easily tuneable design for home-built birdcage probes inducing a linearly polarised B1 field. A simple tuning method is proposed which preserves the induced field homogeneity that characterises in general the birdcage design. This is achieved by adding two extra rings (link rings) that allow one to connect two opposed points on the birdcage end rings via tuning capacitors. All the development stages, from design to practical realisation, are presented, step by step, in order to facilitate experimentalist work. Some images obtained with the birdcage probe are presented, accompanied by the B1 maps in transverse as well as longitudinal planes. Finally, a few suggestions are made for obtaining a circularly polarised magnetic field configuration.

Synthesis and Cytotoxic Evaluation of Two Novel Anthraquinone Derivatives.

AbstractFor Abstract see ChemInform Abstract in Full Text.