Conformal Charge Research Articles

Conformal scalar NUT-like dyons in conformal electrodynamics

We construct conformally scalar NUTty dyon black holes in non-linear electrodynamics (NLE) which possess conformal and duality-rotation symmetries and are characterized by a free dimensionless parameter. The thermodynamic first law of the black hole is formulated. Then we explore the strong gravitational effects of the black hole, mainly focusing on the innermost stable circular orbits (ISCOs) of massive particles and shadows formed by the photons. One of our interesting results is that if the black hole is endowed with a positive real conformal scalar charge rendering it Reissner-Nordstr\"om-like, the radii of the ISCOs and the shadow both increase with the increasing NLE parameter signifying the increasing nonlinearity of the electromagnetic field.

Embedding Azobenzol-Decorated Tetraphenylethylene into the Polymer Matrix to Implement a Ternary Memory Device with High Working Temperature/Humidity.

The development of new high-density memories that can work in harsh environments such as high temperature and humidity will be significant for some special occasions such as oil and geothermal industries. Herein, a facial strategy for implementing a ternary memory device with high working temperature/humidity was executed. In detail, an asymmetric aggregation-induced-emission active molecule (azobenzol-decorated tetraphenylethylene, i.e., TPE-Azo) was embedded into flexible poly(ethylene-alt-maleic anhydride) (PEM) to prepare a TPE-Azo@PEM composite, which served as an active layer to fabricate the FTO/TPE-Azo@PEM/Ag device. This device can demonstrate excellent ternary memory performances with a current ratio of 1:104.2:101.6 for "OFF", "ON1", and "ON2" states. Specially, it can exhibit good environmental endurance at high working temperature (350 °C) and humidity (RH = 90%). The ternary memory mechanism can be explained as the combination of aggregation-induced current/conductance and conformational change-induced charge transfer in the TPE-Azo molecule, which was verified by Kelvin probe force microscopy, UV-vis spectra, X-ray diffraction, and single-crystal structural analysis. This strategy can be used as a universal method for the construction of high-density multilevel memristors with good environmental tolerance.

Di-gluonium sum rules, I = 0 scalar mesons and conformal anomaly

We revisit, scrutinize, improve, confirm and complete our previous results [1–4] from the scalar di-gluonium sum rules within the standard SVZ-expansion at N2LO without instantons and beyond the minimal duality ansatz: “one resonance ⊕ QCD continuum” parametrization of the spectral function which is necessary for a better understanding of the complex spectra of the I=0 scalar mesons. We select different (un)subtracted sum rules (USR) moments of degree ≤ 4 for extracting the two lowest gluonia masses and couplings. We obtain: [MσB,fσB]=[1.07(13),0.46(16)],[MG1,fG1]=[1.55(12),0.37(11)] GeV and the corresponding masses of the radial excitations: MσB′=1.11(12) and MG1′=1.56(14) GeV which are (unexpectedly) almost degenerated with the ground states. The 2nd radial excitation is found to have a much heavier mass: MG2≃ 2.99(22) GeV. Combining these results with some Low-Energy Vertex Sum Rules (LEV-SR), we predict some hadronic widths and classify these states into two groups: – The σ-like (σB,σB′) which decay copiously to ππ from OZI-violating process and the σB′ to 2(ππ)S through σσ. – The G-like (G1,G1′ and eventually G2) which decay into η′η,ηη through the U(1)A gluonic vertex. Besides some eventual mixings with quarkonia states, we may expect that the observed σ/f0(500) and f0(1.37) are σ-like while the f0(1.5) and f0(1.7) are G-like gluonia. The high mass G2(2.99) can also mix with the G1,G1′ to bring the gluon component of the gluonia candidates above 2 GeV. We also estimate the conformal charge ψG(0)=2.09(29) GeV4 and its slope 102×ψG′(0)=−22(29) GeV2. Our results are summarized in Table 1.

Structural, spectroscopic, in silico, in vitro and DNA binding evaluations of tyrosyl-lysyl-threonine

The main objective of the present study is to investigate the molecular structure and DNA binding interaction of the tyrosyl-lysyl-threonine (YKT) tripeptide, which has anticancer, antioxidant and analgesic properties, using various in silico (MD, QM, molecular docking), spectroscopic (UV, FT-IR, FTIR-ATR, Raman, gel electrophoresis) and in vitro (MCF-7 and HeLa cancer cell lines and BEAS-2B cell line) methods. The optimized geometry, vibrational wavenumbers, molecular electrostatic potential (MEP), natural bond orbital (NBO) and HOMO-LUMO (highest occupied molecular orbital- lowest unoccupied molecular orbital) calculations were carried out with Density Functional Theory (DFT) using B3LYP/6-311++G(d,p) basis set to indicate conformational, vibrational and intramolecular charge transfer characteristics. The assignment of all fundamental theoretical vibration wavenumbers was performed using potential energy distribution analysis (PED). DNA is a significant pharmacological target of drugs in several diseases such as cancer. For this reason, molecular docking calculation was used to elucidate the binding and interaction between YKT tripeptide and DNA at the atomic level. Also, the dynamic behaviors of YKT and DNA was examined using MD simulations. Besides, the interaction of YKT with DNA was experimentally examined by UV titration method and agarose gel electrophoresis method. Experimental results showed that YKT was intercalatively and electrostatically bound to CT-DNA (Calf thymus DNA) and cleavage pBR322 DNA in the presence of H2O2. The pharmacokinetic profile of YKT was also obtained. Cytotoxic effect of YKT was evaluated on MCF-7, HeLa and BEAS-2B cell lines. Hence, these studies about YKT tripeptide may pave the way for the development of various cancer drugs. Communicated by Ramaswamy H. Sarma

Novel polyamides with pendant p-phenylenediamine and α-/β-substituted naphthalene: synthesis, characteristics, and effects of substitution sites on electro-switchable optical behaviors

Recently, electro-switchable optical materials have attracted much attention for their promising applications in optoelectronic devices and biological analysis. The structures of active optical moieties are dominant for the resulting performance, which raises the requirement of studying their structure-property relationship. In this study, two p-phenylenediamine–based polyamides (α-HPA and β-HPA) containing α-/β-substituted pendant naphthalene were designed and synthesized to investigate the effect of two substitution sites of naphthalene on their thermal, optical, electrochemical, electrochromic, and electrofluorochromic behaviors. Quantum chemical calculations were carried out to help the analysis of the experimental results. The as-prepared polyamides both exhibited excellent solubility, thermal stabilities (no weight loss before 300 °C in air), and optical switching stability (500 cycles). Because of the more twisted conformation and stronger charge transfer effect between diphenylamine and α-substituted naphthalene, the α-HPA exhibited higher glass transition temperature, higher coloration efficiency, weaker fluorescence quantum efficiency, red-shifted emission wavelength, and rapider switching speed than the β-HPA. This study not only presents a deep understanding of substitution sites of fluorophores on the electro-switchable optical behaviors but also demonstrates the tailorability of the electrochromic/electrofluorochromic characteristics through fine structure adjustment, paving a pathway for further development of high-performance electrochromic/electrofluorochromic materials.

Interaction of graphene oxide with lysozyme:Insights from conformational structure and surface charge investigations

Lysozyme (Lyz) is an important antibacterial protein that exists widely in nature. In recent years, the application of graphene oxide (GO) in the field of biotechnology electronics, optics, chemistry and energy storage has been extensively studied. However, due to the unique properties of GO, the mechanism of its interaction with biomacromolecule proteins is very complex. To further explore the interaction between GO and proteins we explore the influence of different pH and heat treatment conditions on the interaction between GO and Lyz, the GO (0–20 μg/mL) was added at a fixed Lyz concentration (0.143 mg/mL) under different pHs. The structure and surface charge changes of Lyz were measured by spectroscopic analysis and zeta potential. The results showed that the interaction between GO and Lyz depends on temperature and pH, significant changes have taken place in its tertiary and secondary structures. By analyzing the UV absorption spectrum, it was found that lysozyme and GO formed a stable complex, and the conformation of the enzyme was changed. In acidic pH conditions (i.e., pH < pI), a high density of Lyz were found to adsorb on the GO surface, whereas an increase in pH resulted in a progressive decrease in the density of the adsorbed Lyz. This pH-dependent adsorption is ascribed to the electrostatic interactions between the negatively charged GO surface and the tunable ionization of the Lyz molecules. The secondary structure of Lyz adsorbed on GO was also found to be highly dependent on the pH. In this paper, we investigated the exact mechanism of pH-influenced GO binding to lysozyme, which has important guidance significance for the potential toxicity of GO biology and its applications in biomedical fields such as structure-based drug design.

Efficacy of antimicrobial peptides (AMPs) against Escherichia coli and bacteria morphology change after AMP exposure

In recent years, bacterial drug resistance has become a major health concern worldwide owing to the limited efficacy of some traditional antibiotics after long-term usage. Here, to search for potent bacteriostatic agents, six cationic antimicrobial peptides (AMPs) were investigated. L-GL13K, D-GL13K, MSI-594, indolicidin, Ib-M6 and nisinA-S29A were selected to study their bactericidal efficiency and the antibacterial mechanisms against Escherichia coli (E. coli). In addition to half-maximal inhibitory concentration (IC50) and minimum inhibitory concentration (MIC) determinations using the standard method, the initial bacterial growth profiles at 4 h of AMP exposure were used to study the possible antibacterial mechanisms. The AMP-treated E. coli exhibited collapsed cell walls and various nanosized and microsized pores on the bacterial surface, which led to transmembrane channels and pore formation. Among the studied peptides, MSI-594, D-GL13K, and L-GL13K (in decreasing order) were identified as superior bactericidal agents, which may be attributed to the suitable conformational structure and surface charge during the interaction between these AMPs and bacteria.

3d N=4 Bootstrap and Mirror Symmetry

We investigate the non-BPS realm of 3d {N} = 4N=4 superconformal field theory by uniting the non-perturbative methods of the conformal bootstrap and supersymmetric localization, and utilizing special features of 3d {N} = 4N=4 theories such as mirror symmetry and a protected sector described by topological quantum mechanics (TQM). Supersymmetric localization allows for the exact determination of the conformal and flavor central charges, and the latter can be fed into the mini-bootstrap of the TQM to solve for a subset of the OPE data. We examine the implications of the Z_2Z2 mirror action for the SCFT single- and mixed-branch crossing equations for the moment map operators, and apply numerical bootstrap to obtain universal constraints on OPE data for given flavor symmetry groups. A key ingredient in applying the bootstrap analysis is the determination of the mixed-branch superconformal blocks. Among other results, we show that the simplest known self-mirror theory with SU(2) \times SU(2)SU(2)×SU(2) flavor symmetry saturates our bootstrap bounds, which allows us to extract the non-BPS data and examine the self-mirror Z_2Z2 symmetry thereof.

Spiro Rhodamine-Perylene Compact Electron Donor-Acceptor Dyads: Conformation Restriction, Charge Separation, and Spin-Orbit Charge Transfer Intersystem Crossing.

Spiro rhodamine (Rho)-perylene (Pery) electron donor-acceptor dyads were prepared to study the spin-orbit charge transfer intersystem crossing (SOCT-ISC) in these rigid and sterically congested molecular systems. The electron-donor Rho (lactam form) moiety is attached via the N-C bond to the electron acceptor at either 1- or 3-position of the Pery moiety (Rho-Pery-1 and Rho-Pery-3). Severe torsion of the Pery moiety in Rho-Pery-1 was observed. The fluorescence of the two dyads is significantly quenched in polar solvents, and the singlet oxygen quantum yields (ΦΔ) are strongly dependent on solvent polarity (4-36%). Femtosecond transient absorption spectra demonstrate that charge separation (CS) takes 0.51 ps in Rho-Pery-1 and 5.75 ps in Rho-Pery-3, and the charge recombination (CR)-induced ISC is slow (>3 ns). Nanosecond transient absorption spectra indicate that the formation of triplet states via SOCT-ISC takes 24-75 ns for Rho-Pery-1 and 6-15 ns for Rho-Pery-3, and the distorted π-framework of the Pery moiety results in a shorter triplet lifetime of 19.9 vs 291 μs for the planar analogue. Time-resolved electron paramagnetic resonance spectroscopy confirms the SOCT-ISC mechanism.

Boundary conformal invariants and the conformal anomaly in five dimensions

In odd dimensions the integrated conformal anomaly is entirely due to the boundary terms [1]. In this paper we present a detailed analysis of the anomaly in five dimensions. We give the complete list of the boundary conformal invariants that exist in five dimensions. Additionally to 8 invariants known before we find a new conformal invariant that contains the derivatives of the extrinsic curvature along the boundary. Then, for a conformal scalar field satisfying either the Dirichlet or the conformal invariant Robin boundary conditions we use the available general results for the heat kernel coefficient a5, compute the conformal anomaly and identify the corresponding values of all boundary conformal charges.

Silver-coated silicon nanowire platform discriminates genomic DNA from normal and malignant human epithelial cells using label-free Raman spectroscopy

Genomic deoxyribonucleic acid (DNA) stores and carries the information required to maintain and replicate cellular life. While much efforts have been devoted in decoding the sequence of DNA basis to detect the genetic mutations related to cancer disease, it is becoming clear that physical properties, like structural conformation, stiffness and shape, can play an important role to recognize DNA modifications. Here, silver-coated silicon nanowires (Ag/SiNWs) are exploited as Raman spectroscopic platform to easily discriminate healthy and cancer genomic DNA, extracted from human normal skin and malignant melanoma cells, respectively. In particular, aqueous DNA droplets are directly deposited onto a forest of Ag/SiNWs and Raman maps are acquired after sample dehydration. By applying principal component analysis (PCA) to the Raman spectra collected within the droplets, healthy and cancer cell DNA can be distinguished without false negative identifications and with few false positive results (< 2%). The discrimination occurs regardless the analysis of specific DNA sequencing, but through Raman bands strictly related to the interfacing of the DNA and the NWs. The observed phenomenon can be ascribed to conformational differences and/or diverse charge properties between healthy and cancer cell DNA determining a different arrangement of the molecules adsorbed onto the NWs upon water evaporation. The unique interaction with DNA and facile fabrication technology make Ag/SiNWs an effective platform for a robust, rapid and label-free cancer diagnosis, as well as a potential tool to investigate physical properties of DNA.

Effect of surface charge conditions of carriers on the immobilization of β-d-glucosidase

In this study, a series of acidic or alkaline polypeptide chains were designed and grafted onto DEG-AM resin using Fmoc solid-phase synthesis to study the relationship between enzyme conformation and carrier surface charge. β-d-glucosidase (βGase) was then immobilized onto these modified carriers by adsorption. Each form of immobilized βGase showed decreasing specific activity compared to that of the free. It could be attributed to both the changes in the enzyme conformation and the decrease in mass transfer efficiency. The optimum temperature of free βGase, DEG@B3-βGase is 55 °C, which of DEG@A3-βGase is 65 °C and they all have the highest activity at pH 5. The Ea values ​​of free βGase, DEG@A3-βGase, and DEG@B3-βGase are 0.546 kJ/mol, 0.224 kJ/mol, and 0.446 kJ/mol, and the Km values were 1.30 mmol/L, 1.44 mmol/L and 2.63 mmol/L, respectively. It shows that free βGase and DEG@A3-βGase are more similar. Meanwhile, the free βGase (1.0 g/L, pH 5.0) stored at 4 °C has a shorter half-life (t1/2), which is only 9 days. However, the half-life of DEG@B3-βGase and DEG@A3-βGase is 20 days and over 60 days, indicating that the negative charged surface was conducive to maintenance of the structure and catalytic property of βGase.

Utilization of conformation change and charge trapping to achieve binary/ternary rewritable memory performance of carbazole-based organic molecules

To better understand the relationship between the molecular structure and memory characteristics, two carbazole-based organic compounds (Cz-2Ph3F 6FDA and Cz-2TPA 6FDA) with different ratios of electron-donating and electron-withdrawing units were designed and synthesized.

Dynamic adjustment of emission from both singlets and triplets: the role of excited state conformation relaxation and charge transfer in phenothiazine derivates

Dynamic adjustment of emission behaviours by controlling the extent of twisted intramolecular charge transfer character in excited state.

Conformational state and charge determine the interfacial film formation and film stability of β-lactoglobulin

The mechanical stability of protein-stabilized emulsions depends on physiochemical interactions within the interfacial protein film. However, intermolecular interactions vary with the protein's conformational state and charge and may in turn affect the mechanical stability through modifications in the three-staged interfacial stabilization; migration, adsorption and film formation at the oil/water-interface. Therefore, the aim of our study was to investigate the different protein conformations within the interfacial stabilization process by applying bulk water conditions and to determine the protein film stability against mechanical stress. For this purpose, we analyzed the structure and interactions of β-lactoglobulin in water and at the oil/water-interface at pH 7, pH 7NaCl (containing 100 mM NaCl) and pH 9 with membrane-osmometry, Fourier-transform-infrared-spectroscopy, extrinsic fluorescence and ζ-potential. Moreover, we characterized the conformational state and charge in context with the molecule density and interfacial film properties via Langmuir trough analysis, interfacial shear and dilatational rheology. Distinct unfolding of monomers and dimers at pH 9 resulted in the lowest interfacial molecule density but at the same time the highest film stability due to pronounced structural flexibility. In comparison, β-lactoglobulin at pH 7 was monomeric, unfolding was less pronounced, and interfacial molecule density was higher. Electrostatic shielding of β-lactoglobulin dimers at pH 7NaCl resulted in the highest density but least stable protein film that approached low molecular weight surfactant behavior due to few and weak intermolecular interactions. Our research contributes to the control of the emulsion stability against mechanical stress by varying intermolecular interactions within the interfacial protein film.

The cosmological constant from conformal transformations: Möbius invariance and Schwarzian action

The homogeneous Friedman–Lemaî tre-Robertson–Walker (FLRW) cosmology of a free scalar field with vanishing cosmological constant was recently shown to be invariant under the one-dimensional conformal group acting as Möbius transformations on the proper time. Here we generalize this analysis to arbitrary transformations of the proper time, , which are not to be confused with reparameterizations of the time coordinate. First, we show that the FLRW cosmology with a non-vanishing cosmological constant Λ ≠ 0 is also invariant under a group of conformal transformations. The associated conformal Noether charges form a Lie algebra which encodes the cosmic evolution. Second, we show that a cosmological constant can be generated from the Λ = 0 case through particular conformal transformations, realizing a compactification or de-compactification of the proper time depending on the sign of Λ. Finally, we propose an extended FLRW cosmological action invariant under the full group of conformal transformations on the proper time, by promoting the cosmological constant to a gauge field for conformal transformations or by modifying the scalar field action to a Schwarzian action. Such a conformally-invariant cosmology leads to a renewed problem of time and to the necessity to re-think inflation in purely time-deparameterized terms.

Phenothiazine and diphenylsulfone-based donor–acceptor π-systems exhibiting remarkable mechanofluorochromism

Two donor–acceptor luminophores PTZ-DPS and BPTZ-DPS, which are constructed by electron-donor phenothiazine and electron-acceptor diphenylsulfone moiety, are designed and synthesized. Through the effective combination of phenothiazine and diphenylsulfone unit, PTZ-DPS and BPTZ-DPS molecules adopt twisted molecular conformation, unique intramolecular charge transfer (ICT) behavior and intense fluorescence in both solution and solid state. The solid-state luminescence efficiencies of the two luminophores reach 32.84% and 39.69%, respectively. It is particularly noteworthy that both PTZ-DPS and BPTZ-DPS exhibit switchable mechanofluorochromism with high contrast. Upon external force stimulation, the fluorescence colors of the PTZ-DPS and BPTZ-DPS solid powders that change dramatically from initial bright green and yellow to orange, respectively, are observed. Meanwhile, the emission bands red shift from 499 nm to 564 nm–589 nm and 592 nm, respectively, suggesting the large spectral red shifts of 90 nm and 28 nm. Moreover, the mechanofluorochromic (MFC) behavior of PTZ-DPS and BPTZ-DPS also show good reversibility when fume the ground powders by DCM vapor. PXRD and spectral data suggest that the phase transition between crystalline to amorphous states is responsible for MFC behavior of PTZ-DPS and BPTZ-DPS, and the red-shift in the PL spectrum upon grinding originates from the planarization of the molecular conformation and subsequent planar intramolecular charge transfer (PICT).

Interactions between carbon-based nanoparticles and steroid hormone micropollutants in water

The occurrence of micropollutants (MPs) including steroid hormones is a global environmental and health challenge. Carbon-based nanoparticles can be incorporated with water treatment processes to allow MP removal by adsorption. The aim was to compare the suitability of such nanoparticles (graphene, graphene oxide, carbon nanotubes and C60) to adsorb steroid hormones for later incorporation in membrane composites. All nanoparticles displayed fast kinetics; carbon nanotubes and graphene showed high adsorption capacities for hormones undeterminable in isotherm studies (over 10 mg/g). External surface adsorption appears to be the most prominent factor impacting adsorption performance. Structure, conformation, geometry and surface charge of nanoparticles can influence the accessibility of surface area through colloidal instability in aqueous solution. Mechanism inspection shows that adsorption initiates at long ranges (up to 10 nm) through hydrophobic and electrostatic interactions. At relatively short ranges (0.2–0.5 nm), adsorption is enhanced by π/π stacking, XH / π (X = C, O) interactions, van der Waals forces and hydrogen bonding. Both long- and short-range forces transporting hormones from the liquid bulk into the adsorbed phase could control the rate. With relatively short residence time required and high adsorption capacity, carbon nanotubes and graphene are promising for incorporation in a membrane composite.

Anomaly inflow, accidental symmetry, and spontaneous symmetry breaking

We consider the 6d (1,0) SCFT on a stack of N M5-branes probing a ℂ2/ℤ2 singularity. In particular, we study its compactifications to four dimensions on a smooth genus-g Riemann surface with non-trivial flavor flux, yielding a family of 4d CFTs. By tracking the M-theory origin of the global symmetries of the 4d CFTs, we detect the emergence of an accidental symmetry and the spontaneous symmetry breaking of a U(1) generator. These effects are visible from geometric considerations and not apparent from the point of view of the compactification of the 6d field theory. These phenomena leave an imprint on the ’t Hooft anomaly polynomial of the 4d CFTs, which is obtained from recently developed anomaly inflow methods in M-theory [1]. In the large-N limit, we identify the gravity dual of the 4d setups to be a class of smooth AdS5 solutions first discussed by Gauntlett-Martelli-Sparks-Waldram. Using our anomaly polynomial, we compute the conformal central charge and a non-Abelian flavor central charge at large N , finding agreement with the holographic predictions.

Yang–Baxter integrable dimers on a strip

The dimer model on a strip is considered as a Yang–Baxter integrable six vertex model at the free-fermion point with crossing parameter and quantum group invariant boundary conditions. A one-to-many mapping of vertex onto dimer configurations allows for the solution of the free-fermion model to be applied to the anisotropic dimer model on a square lattice where the dimers are rotated by compared to their usual orientation. In a suitable gauge, the dimer model is described by the Temperley–Lieb algebra with loop fugacity . It follows that the model is exactly solvable in geometries of arbitrary finite size. We establish and solve transfer matrix inversion identities on the strip with arbitrary finite width N. In the continuum scaling limit, in sectors with magnetization Sz, we obtain the conformal weights where . We further show that the corresponding finitized characters decompose into sums of q-Narayana numbers or, equivalently, skew q-binomials. In the particle representation, the local face tile operators give a representation of the fermion algebra and the fermion particle trajectories play the role of nonlocal degrees of freedom. We argue that, in the continuum scaling limit, there exist nontrivial Jordan blocks of rank 2 in the Virasoro dilatation operator L0. This confirms that, with quantum group invariant boundary conditions, the dimer model gives rise to a logarithmic conformal field theory with central charge c = −2, minimal conformal weight and effective central charge . Our analysis of the structure of the ensuing rank 2 modules indicates that the familiar staggered c = −2 modules appear as submodules.