Charged Shell Research Articles

Charged Dyson shells supported in curved spacetimes of spherically symmetric central compact objects

It is proved that charged thin shells (charged Dyson shells) can be supported in unstable static equilibrium states around spherically symmetric central compact objects. The regime of existence of the composed central-compact-object-static-charged-shell configurations is characterized by the inequalities m(m+2M)<|q|<M+M2+m2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{m(m+2M)}<|q|<M+\\sqrt{M^2+m^2}$$\\end{document}, where {m,q}\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\{m,q\\}$$\\end{document} are respectively the proper mass and the electric charge of the supported shell and M is the mass of the central compact object (a black hole or an horizonless compact star). We reveal the physically interesting fact that the supported charged shells become marginally-stable in the |q|/m(m+2M)→1+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$|q|/\\sqrt{m(m+2M)}\\rightarrow 1^+$$\\end{document} limit, in which case the lifetime (instability timescale) of the composed system can be made arbitrarily large. Our analysis goes beyond the test shell approximation by properly taking into account the exact gravitational and electromagnetic self-interaction energies of the spherically symmetric shell in the curved spacetime. In particular, the existence of the composed compact-object-charged-shell static configurations in the Einstein–Maxwell theory is attributed to the non-linear electromagnetic self-energy of the supported shell.

Fluorocarbon-Functionalized Polymerization-Induced Self-Assembly Nanoparticles Alleviate Hypoxia to Enhance Sonodynamic Cancer Therapy.

Sonodynamic therapy (SDT) is an ultrasound-based, noninvasive cancer treatment that targets tumor cells by triggering reactive oxygen species production. However, the limited accumulation of sonosensitizers and the insufficient supply of O2 to the hypoxic environment at the tumor site greatly limit the effectiveness of SDT. To address these issues, positively charged porphyrin-containing nanoparticles (NPs) from self-assembling of fluorocarbon/polyethylene glycol amphiphilic block copolymer, which is synthesized through reversible addition-fragmentation chain transfer polymerization, are constructed. The NPs with fluorocarbon core and positively charged hydrophilic shells not only stabilize the sonosensitizer and improve its cellular uptake, but also act as an O2 carrier alleviating the hypoxic tumor environment. In vitro and in vivo experiments demonstrate that the NPs effectively deliver O2 to the tumor and supply sufficient O2 to Renca cells after ultrasound treatment. Consequently, the NPs inhibit hypoxia-induced resistance to SDT and significantly produce reactive oxygen species by activated porphyrin moieties, inducing apoptosis in cancer cells. These oxygen-enhanced sonosensitizer NPs hold promise for cancer therapies such as photodynamic therapy, radiotherapy, and chemotherapy by overcoming hypoxia-induced resistance.

Finite Nuclear Size Effect on the Relativistic Hyperfine Splittings of 2s and 2p Excited States of Hydrogen-like Atoms

Hyperfine splittings play an important role in quantum information and spintronics applications. They allow for the readout of the spin qubits, while at the same time providing the dominant mechanism for the detrimental spin decoherence. Their exact knowledge is thus of prior relevance. In this work, we analytically investigate the relativistic effects on the hyperfine splittings of hydrogen-like atoms, including finite-size effects of the nucleis’ structure. We start from exact solutions of Dirac’s equation using different nuclear models, where the nucleus is approximated by (i) a point charge (Coulomb potential), (ii) a homogeneously charged full sphere, and (iii) a homogeneously charged spherical shell. Equivalent modelling has been done for the distribution of the nuclear magnetic moment. For the 1s ground state and 2s excited state of the one-electron systems H1, H2, H3, and He+3, the calculated finite-size related hyperfine shifts are quite similar for the different structure models and in excellent agreement with those estimated by comparing QED and experiment. This holds also in a simplified approach where relativistic wave functions from a Coulomb potential combined with spherical-shell distributed nuclear magnetic moments promises an improved treatment without the need for an explicit solution of Dirac’s equation within the nuclear core. Larger differences between different nuclear structure models are found in the case of the anisotropic 2p3/2 orbitals of hydrogen, rendering these excited states as promising reference systems for exploring the proton structure.

Effect of degree of substitution of octenyl succinate on starch micelles for synthesis and stability of selenium nanoparticles: Towards selenium supplements

To develop a promising selenium supplement that overcomes the instability and poor water dispersibility of selenium nanoparticles (SeNPs), we synthesized a series of amphiphilic octenyl succinic anhydride starch (OSAS) through esterification. As the degree of substitution (DS) increased, the particle size of OSAS micelles and the critical micelle concentration (CMC) decreased. FTIR and XRD analysis confirmed the successful introduction of octenyl succinic anhydride groups onto starch. Subsequently, OSAS micelles were used as carriers to synthesize SeNPs via in situ chemical reduction, forming SeNPs-loaded self-assembled starch nano-micelles (OSAS-SeNPs). The OSAS-SeNPs exhibited spherical dispersion in water with an average diameter of 116.1 ± 2.3 nm, contributed to enhanced hydrophobic interactions. TEM images showed a core-shell structure with SeNPs as the core and OSAS as the shell. FTIR results indicated hydrogen bonding interactions between OSAS and SeNPs. Due to the negatively charged OSAS shell and hydrogen bonding (OH⋯Se), OSAS-SeNPs remained non-aggregated for one month at room temperature, demonstrating remarkable stability. This study suggests that using OSAS can address the synthesis and stability issues of SeNPs, making it a potential selenium supplement candidate for further evaluation as an anticancer agent.

Nanosized Complexes of the Proteolytic Enzyme Serratiopeptidase with Cationic Block Copolymer Micelles Enhance the Proliferation and Migration of Human Cells.

In this study, we describe the preparation of the cationic block copolymer nanocarriers of the proteolytic enzyme serratiopeptidase (SER). Firstly, an amphiphilic poly(2-(dimethylamino)ethyl methacrylate)-b-poly(ε-caprolactone)-b-poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA9-b-PCL35-b-PDMAEMA9) triblock copolymer was synthesized by reversible addition-fragmentation chain-transfer (RAFT) polymerization. Then, cationic micellar nanocarriers consisting of a PCL hydrophobic core and a PDMAEMA hydrophilic shell were formed by the solvent evaporation method. SER was loaded into the polymeric micelles by electrostatic interaction between the positively charged micellar shell and the negatively charged enzyme molecules. The particle size, zeta potential, and colloid stability of complexes as a function of SER concentration were investigated by dynamic and electrophoretic light scattering. It was found that SER retained its proteolytic activity after immobilization in polymeric carriers. Moreover, the complexes have a concentration-dependent enhancing effect on the proliferation and migration of human keratinocyte HaCaT and gingival fibroblast HGF cells.

Targeted lipid-coated ZnO nanoparticles coupled with ultrasound: A sonodynamic approach for the treatment of osteosarcoma as 3D spheroid models

Bone cancer is a rare disease with limited treatment options. Surgery and chemotherapy frequently fail to cure the disease because metastases can develop in the former, and the latter often lacks specificity. Innovative therapeutic treatments are therefore needed to address this rare disease, which typically affects children and adolescents. Physical stimulation to remotely activate a therapeutic agent may represent a promising solution, especially for deep-seated and/or distributed tumors. In this regard, sonodynamic therapy gathers importance: it offers a valid solution to the limitations of photodynamic therapy, such as limited tissue penetration, but retains the advantages of remotely activatable cell death. In this work, we developed lipidic coated iron-doped zinc oxide nanoparticles with superior biocompatibility as remotely activated sonosensitizers for osteosarcoma sonodynamic therapy and an active targeting mechanism addressing the erythropoietin-producing hepatocellular receptor-2 overexpressed in bone cancer cells. The positively charged zinc oxide NPs are coated with a negatively charged phospholipidic shell, which significantly enhances the biocompatibility and hemocompatibility of the nanoconstruct. Most importantly, the lipidic shell is modified by grafting a targeting peptide onto it, increasing cellular uptake towards osteosarcoma cells and demonstrating the potential to address various tissues with the same system. Reactive Oxygen Species (ROS) are effectively generated upon ultrasound stimulation and measured through electron paramagnetic resonance spectroscopy. The nanoconstructs are evaluated in vitro on 3D osteosarcoma spheroids, to demonstrate the effectiveness of the combination of NPs and ultrasound stimulation in suppressing the growth of bone osteosarcoma. The biocompatibility, targeting capabilities, and potential flexibility of the nanoparticles here described open up avenues for an effective and remotely-activated cancer therapy.

Specificities of Throwing the Shell of a Cylindrical Cumulative Charge to the Axis

Specificities of Throwing the Shell of a Cylindrical Cumulative Charge to the Axis

Advances in 2,3-Dimethylmaleic Anhydride (DMMA)-Modified Nanocarriers in Drug Delivery Systems.

Cancer represents a significant threat to human health. The cells and tissues within the microenvironment of solid tumors exhibit complex and abnormal properties in comparison to healthy tissues. The efficacy of nanomedicines is inhibited by the presence of substantial and complex physical barriers in the tumor tissue. The latest generation of intelligent drug delivery systems, particularly nanomedicines capable of charge reversal, have shown promise in addressing this issue. These systems can transform their charge from negative to positive upon reaching the tumor site, thereby enhancing tumor penetration via transcytosis and promoting cell internalization by interacting with the negatively charged cell membranes. The modification of nanocarriers with 2,3-dimethylmaleic anhydride (DMMA) and its derivatives, which are responsive to weak acid stimulation, represents a significant advance in the field of charge-reversal nanomedicines. This review provides a comprehensive examination of the recent insights into DMMA-modified nanocarriers in drug delivery systems, with a particular focus on their potential in targeted therapeutics. It also discusses the synthesis of DMMA derivatives and their role in charge reversal, shell detachment, size shift, and ligand reactivation mechanisms, offering the prospect of a tailored, next-generation therapeutic approach to overcome the diverse challenges associated with cancer therapy.

Stability of GMGHS charged thin shell wormhole in string theory

Stability of GMGHS charged thin shell wormhole in string theory

Collapse of concrete target subjected to embedded explosion of shelled explosive

This paper broadens previous research concerning spalling damage in concrete structures under buried explosions, by additionally examining the effects of shell thickness and shell head length of the warhead experimentally and numerically. In the experiment, concrete targets were subjected to the embedded explosion of cylindrical shelled explosives with different charge masses, shell thicknesses, and shell head lengths. The results reveal that thicker charge shells and longer shell heads decrease the surface area and the depth of spalling damage on the rear surface of concrete structures. In addition, to investigate the damage mechanism and predict the critical collapse thickness (CCT), two- and three-dimensional finite-element models were developed and correlated well with the experimental results. Parametric analyses are also applied to examine how the embedded depth, length-to-diameter ratio, shell thickness, and shell head length affect the CCT for a buried explosion. Finally, an empirical formula is proposed to estimate the CCT based on these factors.

Targeted anti-cancer therapy: Co-delivery of VEGF siRNA and Phenethyl isothiocyanate (PEITC) via cRGD-modified lipid nanoparticles for enhanced anti-angiogenic efficacy

Anti-tumor angiogenesis therapy, targeting the suppression of blood vessel growth in tumors, presents a potent approach in the battle against cancer. Traditional therapies have primarily concentrated on single-target techniques, with a specific emphasis on targeting the vascular endothelial growth factor, but have not reached ideal therapeutic efficacy. In response to this issue, our study introduced a novel nanoparticle system known as CS-siRNA/PEITC&L-cRGD NPs. These chitosan-based nanoparticles have been recognized for their excellent biocompatibility and ability to deliver genes. To enhance their targeted delivery capability, they were combined with a cyclic RGD peptide (cRGD). Targeted co-delivery of gene and chemotherapeutic agents was achieved through the use of a negatively charged lipid shell and cRGD, which possesses high affinity for integrin αvβ3 overexpressed in tumor cells and neovasculature. In this multifaceted approach, co-delivery of VEGF siRNA and phenethyl isothiocyanate (PEITC) was employed to target both tumor vascular endothelial cells and tumor cells simultaneously. The co-delivery of VEGF siRNA and PEITC could achieve precise silencing of VEGF, inhibit the accumulation of HIF-1α under hypoxic conditions, and induce apoptosis in tumor cells. In summary, we have successfully developed a nanoparticle delivery platform that utilizes a dual mechanism of action of anti-tumor angiogenesis and pro-tumor apoptosis, which provides a robust and potent strategy for the delivery of anti-cancer therapeutics.

On the dynamics of a rolling spherical charged shell

In this work, we investigate the behaviour of a charged spherical shell rolling on an inclined plane, in presence of a point charge located at the lowest part of the inclined plane. The shell generates two magnetic fields, one due to its rotation and another due to its translation, These magnetic fields affect the shell through self-inductance. On the other hand, the charge in the lowest part of the inclined plane interacts with the shell, and we find that under certain conditions the spherical shell rolls back and up the inclined plane due to the electric force. We perform a numerical analysis to study this behavior.

Microscale Thermophoresis (MST) to Study Rapid Alkalinization Factor (RALF)-Receptor Interactions.

Microscale thermophoresis (MST) is a simple but powerful tool to study the in vitro interaction among biomolecules, and to quantify binding affinities. MST curves describe the change in the fluorescence level of a fluorescent target as a result of an IR-laser-induced temperature change. The degree and nature of the change in fluorescence signal depends on the size, charge, and solvation shell of the molecules, properties that change in function of the binding of a ligand to the fluorescent target.We used MST to describe the interaction between components of a regulatory module involved in plant cell wall integrity control. This module comprises the secreted peptide Rapid Alkalinization Factor 23 (RALF23) and its receptor complex consisting of the GPI-anchored receptor Lorelei-Like Glycoprotein 1 (LLG1) and a receptor kinase of the CrRLK1L family, FERONIA. Here we show how MST can also be used to study three-partner interactions.

A polyampholyte core-shell microgel as an environmentally sensitive drug carrier

In this study, we investigate a polyampholyte degradable core-shell (CS) microgel, with an anionic pH-sensitive core and a cationic pH- and temperature-sensitive shell, as a model system for drug delivery. The core was based on crosslinked poly(acrylic acid) and was synthesized through distillation precipitation polymerization. Then, the shell, based on cross-linked poly(poly(ethylene glycol) methyl ether methacrylate - N-(3-aminopropyl)methacrylamide), were built over the core via the seed polymerization. N,N′-bis(acryloyl)cystamine was used as the linker for cross-linking both core and shell to give the core-shell particles the ability to degrade in the presence of reducing agent. The swelling characteristics of the core-shell microgels were studied using dynamic light scattering (DLS). The core-shell particles exhibited sensitivity to pH due to the presence of carboxylic and amine groups in the core and shell, respectively. The degradation of the core-shell particles was examined using electron microscopy and DLS. In the presence of glutathione, which acts as a reducing agent for the -S-S- bridges, commonly found in cancer cells, the particles underwent complete degradation. Our findings also demonstrate that the presence of the positively charged shell still enables efficient uptake of a drug in the form of a cation (doxorubicin DOX) into the anionic core and the drug can be released through the cationic shell. The release of DOX from the carrier was studied under different pH conditions to mimic the environment found in cancer cells. The results showed that at pH 7.4, the carrier exhibited the lowest release of DOX. However, under conditions mimicking the acidic and reducing environment typically for tumor microenvironment (pH 5.0 and cGSH = 40 mM), the CS particles demonstrated the highest cumulative and sustained release of DOX. The results showed that the DOX-loaded particles exhibited increased cytotoxicity against MCF-7 cells, indicating enhanced anti-cancer activity. At the same time, these particles demonstrated reduced toxicity towards healthy MCF-10A cells, which suggests improved selectivity and reduced side effects. It is worth noting that the gel nanoparticles alone did not inhibit cell growth. Overall, these findings suggest that the DOX-loaded core-shell particles hold promise as a targeted drug delivery system, capable of preferentially releasing the drug in the acidic and reducing tumor microenvironment while minimizing toxicity towards healthy cells.

Local Environments Created by the Ligand Coating of Nanoparticles and Their Implications for Sensing and Surface Reactions.

ConspectusThe ligand shells of colloidal nanoparticles (NPs) can serve different purposes. In general, they provide colloidal stability by introducing steric repulsion between NPs. In the context of biological applications, the ligand shell plays a critical role in targeting, enabling NPs to achieve specific biodistributions. However, there is also another important feature of the ligand shell of NPs, namely, the creation of a local environment differing from the bulk of the solvent in which the NPs are dispersed. It is known that charged ligand shells can attract or repel ions and change the effective charge of a NP through Debye-Hückel screening. Positively charged ions, such as H+ (or H3O+) are attracted to negatively charged surfaces, whereas negatively charged ions, such as Cl- are repelled. The distribution of the ions around charged NP surfaces is a radial function of distance from the center of the NP, which is governed by a balance of electrostatic forces and entropy of ions and ligands. As a result, the ion concentration at the NP surface is different from its bulk equilibrium concentration, i.e., the charged ligand shell around the NPs has formed a distinct local environment. This not only applies to charged ligand shells but also follows a more general principle of induced condensation and depletion. Polar/apolar ligand shells, for example, result in a locally increased concentration of polar/apolar molecules. Similar effects can be seen for biocatalysts like enzymes immobilized in nanoporous host structures, which provide a special environment due to their surface chemistry and geometrical nanoconfinement. The formation of a local environment close to the ligand shell of NPs has profound implications for NP sensing applications. As a result, analyte concentrations close to the ligand shell, which are the ones that are measured, may be very different from the analyte concentrations in bulk. Based on previous work describing this effect, it will be discussed herein how such local environments, created by the choice of used ligands, may allow for tailoring the NPs' sensing properties. In general, the ligand shell around NPs can be attractive/repulsive for molecules with distinct properties and thus forms an environment that can modulate the specific response. Such local environments can also be optimized to modulate chemical reactions close to the NP surface (for example, by size filtering within pores) or to attract specific low abundance proteins. The importance hereby is that this is based on interaction with low selectivity between the ligands and the target molecules.

Smart microsubmarine shells operated by controlled buoyancy force through metal-ion adsorption/desorption and their biosensor applications

Small and uniform-sized poly(polyethylene glycol (PEG)–co-acrylic acid (AA)) shells engulfing a mineral oil droplet (oil@poly(PEG-co-AA) shells, ∼180 μm) are prepared using the in situ polymerization of the O(mineral oil)–W(PEGDA/AA, PEGDA = polyethylene glycol diacrylate)–O(mineral oil) double emulsion droplets produced in a microfluidic chip. The lightweight oil core and heavy-weight poly(PEG-co-AA) shells exhibit positive buoyancy and negative gravitational forces in water, respectively. Densities of oil@poly(PEG-co-AA) shells were finely tuned in water to be sensitive to a small weight change by controlling microfluidic parameters. The poly(PEG-co-AA) shells are pH-responsive in terms of charged state and shell size. The pH-controlled metal adsorption/desorption at poly(PEG-co-AA) shells breaks the density balance, leading to the sinking or floating of oil@poly(PEG-co-AA) shells in the water. Herein, this levitation and size change of oil@poly(PEG-co-AA) shells are applied to glucose and urea biosensors by immobilizing their enzymes. The divalent (or higher) metal adsorption is distinguishable from monovalent metal adsorption by the diminished size of the oil@poly(PEG-co-AA) shells and their different levitation behavior in water. Thus, these oil@poly(PEG-co-AA) shells facilitate smart motile sensor applications with an unexplored concept, which can be further expanded to other applications such as smart valves in microfluidics and smart windows.

Effect of charge and solvation shell on non-radiative decay processes in s-block cationic metal ion water clusters.

Intermolecular Coulombic decay or electron transfer-mediated decay are the autoionization processes through which a molecule can relax. This relaxation is only possible if the inner valence's ionization potential (IP) exceeds the system's double ionization potential (DIP). To study the effects of charge and solvation shell, we have calculated the IP, DIP values, and lifetime of Na-2s and Mg-2s temporary bound states in various optimized structures of Na+-(H2O)n and Mg2+-(H2O)n (n = 1-5) micro-solvated clusters, where n water molecules are distributed in a way that some are directly bound to the metal ion and the rest to the water molecules. The first and second solvation shells are the names for the former and the latter water-binding positions, respectively. For a given n, the lifetime of decaying states is longer when water molecules are in the second solvation shell. We found that the Mg-2p state can decay for all n values in Mg2+-(H2O)n clusters, whereas the Na-2p state's decay is possible for n ≥ 2 in Na+-(H2O)n clusters. Our findings highlight the influence of metal ions' charge, different solvation shell structures, and the number of water molecules on the decay rate. These systems are relevant to the human body, which makes this study significant.

Calculation of the electromagnetic self-force of a non-lorentz-contractible uniformly charged spherical shell in arbitrary rectilinear motion

Calculation of the electromagnetic self-force of a non-lorentz-contractible uniformly charged spherical shell in arbitrary rectilinear motion

Dual Thermo- and pH-Responsive Block Copolymer of Poly(N-isopropylacrylamide)-block-Poly(N,N-diethylamino Ethyl Acrylamide): Synthesis, Characterization, Phase Transition, and Self-Assembly Behavior in Aqueous Solution

Doubly thermo- and pH-responsive poly(N-isopropylacrylamide)-block-poly(N,N-diethylamino ethyl acrylamide) (PNIPAM-b-PDEAEAM) with different compositions were synthesized by reversible addition–fragmentation chain-transfer (RAFT) polymerization. The properties (solubility, self-assembly behavior) of these polymers and corresponding homopolymers in solution depend on the value of pH and the protonation degree of the diethylamino moiety. The effect of the nature of the polymer chain ends also appears to be critical to fully understand this behavior. At pH 10, both PNIPAM and PDEAEAM blocks are thermoresponsive and make a cooperative contribution to phase transition, and stable spherical nanoobjects are detected as temperature rises over transition point. At pH 4, PNIPAM-b-PDEAEAM with longer PDEAEAM length displays a two-step thermoresponsive behavior; upon heating, PNIPAM chains undergo shrinkage and subsequent reorganization causing the formation of large aggregates with a positively charged shell made of PDEAEAM block in its protonated state. The aggregation processes are also particularly sensitive to kinetic considerations, and therefore, measured size of aggregates depends strongly on the history of polymer solution.

Symmetrized Drude Oscillator Force Fields Improve Numerical Performance of Polarizable Molecular Dynamics

Drude oscillator potentials are a popular and computationally efficient class of polarizable models that represent each polarizable atom as a positively charged Drude core harmonically bound to a negatively charged Drude shell. We show that existing force fields that place all non-Coulomb forces on the Drude core and none on the shell inadvertently couple the dipole to non-Coulombic forces. This introduces errors where interactions with neutral particles can erroneously induce atomic polarization, leading to spurious polarizations in the absence of an electric field, exacerbating violations of equipartition in the employed Carr-Parinello scheme. A suitable symmetrization of the interaction potential that correctly splits the force between the Drude core and shell can correct this shortcoming, improving the stability and numerical performance of Drude oscillator-based simulations. The symmetrization procedure is straightforward and only requires the rescaling of a few force field parameters.