Homogeneous Chain Research Articles

Homogeneous Reversible Addition Fragmentation Chain Transfer Synthesis of Amphiphilic Poly(Styrene-b-Acrylamide) Copolymers and Their Solution Characterization: a Thermogelating and Salinity Resistant Viscosifier from Largely Available Monomers

Homogeneous Reversible Addition Fragmentation Chain Transfer Synthesis of Amphiphilic Poly(Styrene-<i>b</i>-Acrylamide) Copolymers and Their Solution Characterization: a Thermogelating and Salinity Resistant Viscosifier from Largely Available Monomers

Lattice realizations of topological defects in the critical (1+1)-d three-state Potts model

Topological/perfectly-transmissive defects play a fundamental role in the analysis of the symmetries of two dimensional conformal field theories (CFTs). In the present work, spin chain regularizations for these defects are proposed and analyzed in the case of the three-state Potts CFT. In particular, lattice versions for all the primitive defects are presented, with the remaining defects obtained from the fusion of the primitive ones. The defects are obtained by introducing modified interactions around two given sites of an otherwise homogeneous spin chain with periodic boundary condition. The various primitive defects are topological on the lattice except for one, which is topological only in the scaling limit. The lattice models are analyzed using a combination of exact diagonalization and density matrix renormalization group techniques. Low-lying energy spectra for different defect Hamiltonians as well as entanglement entropy of blocks located symmetrically around the defects are computed. The latter provides a convenient way to compute the g-function which characterizes various defects. Finally, the eigenvalues of the line operators in the “crossed channel” and fusion of different defect lines are also analyzed. The results are all in agreement with expectations from conformal field theory.

Nanopore-regulated in situ polymerization for synthesis of homogeneous heparan sulfate with low dispersity

The biological activities of heparan sulfate (HS) are intimately related to their molecular weights, degree and pattern of sulfation and homogeneity. The existing methods for synthesizing homogeneous sugar chains of low dispersity involve multiple steps and require stepwise isolation and purification processes. Here, we designed a mesoporous metal-organic capsule for the encapsulation of glycosyltransferase and obtained a microreactor capable of enzymatically catalyzing polymerization reactions to prepare homogeneous heparosan of low dispersity, the precursor of HS and heparin. Since the sugar chain extension occurs in the pores of the microreactor, low molecular weight heparosan can be synthesized through space-restricted catalysis. Moreover, the glycosylation co-product, uridine diphosphate (UDP), can be chelated with the exposed metal sites of the metal-organic capsule, which inhibits trans-cleavage to reduce the molecular weight dispersity. This microreactor offers the advantages of efficiency, reusability, and obviates the need for stepwise isolation and purification processes. Using the synthesized heparosan, we further successfully prepared homogeneous 6-O-sulfated HS of low dispersity with a molecular weight of approximately 6 kDa and a polydispersity index (PDI) of 1.032. Notably, the HS generated exhibited minimal anticoagulant activity, and its binding affinity to fibroblast growth factor 1 was comparable to that of low molecular weight heparins.

Homogeneous-strengthened SPEEK membrane with ultrahigh conductivity regulated by main/side-chain bisulfonated PEEK for vanadium flow battery

A comblike polymer (SPOS) with a main/side-chain bisulfonated structure has been synthesized with 1,3-propane sulfonate as the pendant chains and poly (ether ketone) (PEEK) as the reactant by the combined post-sulfonation and ring-opening grafting reaction. Taking sulfonated PEEK as a membrane matrix, the composite membranes (S/SPOS) are prepared by the solution-blending method with varied contents of bisulfonic SPOS polymer from 10 to 25 wt%. The S/SPOS composite membranes display superior conductivity owing to synergistic enhancement in the intermolecular chain interactions and the homogeneous strengthened transportation channels from main/side-chain bisulfonic acid interconnected networks. S/SPOS-15 shows better CE (96.5–98.5 %) and EE (84.7–69.9 %) than that of Nafion 212 (CE: 92.3–95.0 %, EE: 76.1–63.7 %) at 100–200 mA cm−2. Moreover, 600-cycled durability and 77.3 % EE at 150 mA cm−2, and 71.8 h self-discharge time demonstrate its improved reliable structure and cyclic stability. This provides a promising method to prepare high-performance and low-cost membranes with desirable conductivity by homogeneous structural regulation and molecular chain synergistic interactions.

Rapid and sensitive parallel on-site detection of antibiotics and resistance genes in aquatic environments using evanescent wave dual-color fluorescence fiber-embedded optofluidic nanochip

Environmental antibiotics and antibiotic resistance genes (ARGs) pose considerable threat to humans and animals; thus, the rapid and sensitive parallel detection of these pollutants from a single sample is urgently required. However, traditional multiplexed analytic technologies detect only one type of target (e.g., small molecules or nucleic acids) per assay. To address this issue, Evanescent wave Dual-color fluorescence Fiber-embedded Optofluidic Nanochip (EDFON) was fabricated by integrating a fiber-embedded optofluidic nanochip with evanescent wave dual-color fluorescence technology. The EDFON was used for the parallel quantitative detection of sulfamerazine (SMR) and MCR-1 with high sensitivity and specificity by combining a heterogeneous immunoassay with a homogenous hybridization chain reaction based on time-resolved effects. LODs of 0.032 μg/L and 35 pM was obtained for SMR and MCR-1, respectively, within 20 min. To our best knowledge, the EDFON is the first device for the simultaneous detection of two type of targets in each test, which is highly valuable to prevent the global threats of antibiotics and ARGs. Comparison with liquid chromatography-mass spectrometry showed a strong linear relationship (R2 = 0.998) for SMR pollution in the Qinghe River, with spiked SMR and MCR-1 negative surface and wastewater samples showing recovery rates of 91.8–113.4%. These results demonstrate the excellent accuracy and reliability of the EDFON, with features such as multi-analyte detection, field-deployment, and minimal-equipment, rendering it revolutionary for environmental monitoring, food safety, and medical diagnostics.

Promising CO2 Capture and Effective Iodine Adsorption of Hyper-Cross-Linked Conjugated Porous Organic Polymers Prepared from a Cyclopentannulation Reaction.

Three novel conjugated porous organic polymers, denoted as C-POP1-3 and which consist of alternating pyrene cores with various contorted fluorene surrogates, were successfully synthesized from a versatile one-pot palladium-catalyzed [3+2] cyclocondensation reaction. The resulting polymers were obtained in excellent yields and displayed weight-average molecular weights (Mw) ranging from 12.2 to 20.2 kg/mol with polydispersity indices (Mw/Mn) ranging between 1.8 and 2.4, suggesting that the molecular masses are narrowly distributed and thus implying homogeneous polymer chains. Thermal stability exploration of C-POP1-3 by thermogravimetric analysis (TGA) revealed an impressive robustness with a 10% weight reduction temperature attaining 485 °C. Investigation of the inherent microporosity properties of C-POP1-3 via nitrogen adsorption experiments using Brunauer-Emmett-Teller (BET) theory discloses their surface areas which reach up to 560 m2 g-1 and pore volumes averaging 0.47 cm3 g-1. The target conjugated polymers were explored as adsorbents disclosing a maximum carbon dioxide adsorption of 83.0 mg g-1 at 273 K and low pressure for C-POP1, whereas iodine sorption tests portrayed prominent outcomes, notably for C-POP3 which proved to owe a strong affinity toward the hitherto mentioned halogen by achieving a maximum adsorption of 2220 mg g-1. Additionally, recyclability experiments confirmed the possibility to regenerate the polymers' adsorption capabilities even after seven consecutive cycles of adsorption-desorption cycles, which qualify them as auspicious iodine adsorbents.

Force-induced unzipping of DNA in the presence of solvent molecules

The melting of double-stranded DNA (dsDNA) in the presence of solvent molecules is a fundamental process with significant implications for understanding the thermal and mechanical behavior of DNA and its interactions with the surrounding environment. The solvents play an essential role in the structural transformation of DNA subjected to a pulling force. In this study, we simulate the thermal and force induced denaturation of dsDNA and elucidate the solvent dependent melting behavior, identifying key factors that influence the stability of DNA melting in presence of solvent molecules. Using a statistical model, we first find the melting profile of short heterogeneous DNA molecules in the presence of solvent molecules in Force ensemble. We also investigate the effect of solvent's strengths on the melting profile of DNA. In the force ensemble, we consider two homogeneous DNA chains and apply the force on different locations along the chain in the presence of solvent molecules. Different pathways manifest the melting of the molecule in both ensembles, and we found several interesting features of melting DNA in a constant force ensemble, such as lower critical force when the chain is pulled from the base pair close to a solvent molecule. The results provide new insights into the force-induced unzipping of DNA and could be used to develop new methods for controlling the unzipping process. By providing a better understanding of melting and unzipping of dsDNA in the presence of solvent molecules, this study provides valuable guidelines for predicting DNA thermodynamic quantities and for designing DNA nanostructures.

Gaussian processes for finite size extrapolation of many-body simulations.

Key to being able to accurately model the properties of realistic materials is being able to predict their properties in the thermodynamic limit. Nevertheless, because most many-body electronic structure methods scale as a high-order polynomial, or even exponentially, with system size, directly simulating large systems in their thermodynamic limit rapidly becomes computationally intractable. As a result, researchers typically estimate the properties of large systems that approach the thermodynamic limit by extrapolating the properties of smaller, computationally-accessible systems based on relatively simple scaling expressions. In this work, we employ Gaussian processes to more accurately and efficiently extrapolate many-body simulations to their thermodynamic limit. We train our Gaussian processes on Smooth Overlap of Atomic Positions (SOAP) descriptors to extrapolate the energies of one-dimensional hydrogen chains obtained using two high-accuracy many-body methods: coupled cluster theory and Auxiliary Field Quantum Monte Carlo (AFQMC). In so doing, we show that Gaussian processes trained on relatively short 10-30-atom chains can predict the energies of both homogeneous and inhomogeneous hydrogen chains in their thermodynamic limit with sub-milliHartree accuracy. Unlike standard scaling expressions, our GPR-based approach is highly generalizable given representative training data and is not dependent on systems' geometries or dimensionality. This work highlights the potential for machine learning to correct for the finite size effects that routinely complicate the interpretation of finite size many-body simulations.

Coupling homogeneous chains of damped harmonic oscillators

We study vibrational properties of non-homogeneous materials. We consider idealized materials composed of one dimensional chains of damped harmonic oscillators represented by a sequence of particles, springs and dampers. The system is linear, thus possesses exact explicit solutions, nevertheless the formulas can be very complicated. Homogeneous chains are used as basic building blocks for characterizing global dynamics of the system. In particular, we determine the solutions for a system composed of two distinct homogeneous chains in terms of the original solutions for these two homogeneous chains, and the original parameters, when uncoupled. Two types of coupling are considered, one with a gluing particle, the other with a gluing spring and damper.

Задача о колебаниях в цепи связанных линейных осцилляторов с демпфирующей и антидемпфирующей границами

The problem of oscillations in a finite homogeneous chain of coupled harmonic oscillators is considered under special boundary conditions that ensure a stable flow of energy from one end of the chain to the other. The problem covers, as special cases, the classical problem of oscillations in a chain with free and fixed ends, as well as the problem of oscillations in a chain with absorbing and anti-absorbing boundaries. Absorbing boundary conditions are used in numerical simulation of wave propagation to minimize the influence of non-physical boundaries. An exact analytical solution to the considered problem is obtained. The dynamical system of the problem is studied. In particular, a description of the invariant subspaces of the system is given. The oscillatory properties of the system are investigated. The phenomenon of a significant increase in the amplitude of low-frequency oscillations has been discovered and studied. The problem is solved in Schrodinger variables. The solution is presented both in terms of infinite series of Bessel functions and in terms of natural oscillations (eigenmodes) of the system.

Transition from a Uniform Mode of Polaron Motion to an Oscillatory One When the Initial Polaron State Changes

A study of the nature of the motion of a Holstein polaron in a homogeneous polynucleotide chain in a constant electric field, depending on the initial polaron state, was carried out. The calculations performed showed that the duration of the uniform motion of the polaron along the chain is finite and depends on the entire set of system parameters, including the characteristic size of the initial polaron state. It is shown that at a fixed value of the electric field intensity, an increase in the characteristic size of the initial polaron state leads to a decrease in the time of uniform motion of the polaron along the chain. The calculations carried out earlier showed that with the uniform movement of the polaron along the chain, low-density components of the polaron are formed immediately after the electric field is turned on. Moreover, the low-density components of the polaron have their own internal dynamics, which are different from the dynamics of the macro-part of the polaron. With uniform motion, the macro-part of the polaron moves at a constant velocity, maintaining its shape, while the low-density components of the polaron demonstrate such characteristics of Bloch oscillations as the period of Bloch oscillations and the maximum Bloch amplitude. It is also shown that a change in the shape of the initial polaron state exerts influence upon not only the duration of the uniform motion of the polaron along the chain, but also the characteristics of the low-density components of the polaron.

Wearable nanocomposite hydrogel temperature sensor based on thermally-switchable and mechanical-deformation-insensitive structural colors

Smart and flexible nanocomposite materials with structural colors have great potentials in the field of wearable sensors. However, the mechanochromic property of conventional photonic materials severely interferes with the optical signal outputs that are tunable by non-strain stimuli, which greatly impedes their applications in wearable photonic sensors. Herein, a wearable nanocomposite hydrogel temperature sensor based on thermally-switchable structural colors that are independent of mechanical deformations, is fabricated by the facile in-situ gelation of N-isopropyl acrylamide (NIPAM), nanoclay discs, carbon black, and monodisperse silica or polymeric NPs in their aqueous dispersions. The resulting non-assembled arrangements of the monodisperse NPs account for uniform structural color independent of mechanical deformations and observation angles. Simultaneously, the temperature-induced reconfiguration of the physically cross-linked poly-NIPAM hydrogel matrix, leads to super-large volume changes and in turn wide-range structural color shifts in almost the entire visible spectrum. The smart hydrogel matrix with homogenous polymer chain length by dynamic physical cross-linkings among exfoliated nanoclay discs, makes the photonic hydrogel robust, stretchable, and self-healable. The combination of mechanical-deformation-insensitive and thermally-switchable structural colors in the nanocomposite hydrogel enables skin-based wearable temperature sensing with naked-eye detection. This work opens a new platform for diverse non-invasive wearable photonic sensors beyond the current strain sensing.

Empirical formulas for predicting the energy attenuation behavior of primary stress waves in 1D composite chain of viscoelastic spheres

One-dimensional composite chain of viscoelastic spheres are potential candidates for novel impact buffers. Understanding the energy attenuation behavior of primary stress waves in the composite chain of viscoelastic spheres is the premise for high-performance impact buffers design. Although the current research included viscoelasticity into the motion equations of spheres, most of them were limited to homogeneous chains. Moreover, the models of discrete system could not give the explicit expressions of the key factors governing the energy attenuation of primary stress waves. The absence of explicit formulas for the key factors hindered efficient optimization design of impact buffers constructed by one-dimensional composite chain of viscoelastic spheres. In this study, empirical formulas for predicting the input amplitude, the attenuation coefficient of the contact force and the transmission coefficient at the interface were constructed. Multivariate nonlinear regression method and dimensional constraint were applied to ensure that all the empirical formulas only employ the impact velocity and the parameters of the used spheres as independent variables. Intermediate factor was introduced for individual key factor to evaluate the accuracy of the empirical formula. Though the groups of empirical formulas have degraded performance in the low range of the intermediate factors, their accuracy in quantitatively predicting the energy attenuation behavior of the stress waves in one-dimensional composite chain of viscoelastic spheres deserves satisfactory.

Mechanistic Study on the Degradation of Hydrolysable Core-Crosslinked Polymeric Micelles.

Core-crosslinked polymeric micelles (CCPMs) are an attractive class of nanocarriers for drug delivery. Two crosslinking approaches to form CCPMs exist: either via a low-molecular-weight crosslinking agent to connect homogeneous polymer chains with reactive handles or via cross-reactive handles on polymers to link them to each other (complementary polymers). Previously, CCPMs based on methoxy poly(ethylene glycol)-b-poly[N-(2-hydroxypropyl) methacrylamide-lactate] (mPEG-b-PHPMAmLacn) modified with thioesters were crosslinked via native chemical ligation (NCL, a reaction between a cysteine residue and thioester resulting in an amide bond) using a bifunctional cysteine containing crosslinker. These CCPMs are degradable under physiological conditions due to hydrolysis of the ester groups present in the crosslinks. The rapid onset of degradation observed previously, as measured by the light scattering intensity, questions the effectiveness of crosslinking via a bifunctional agent. Particularly due to the possibility of intrachain crosslinks that can occur using such a small crosslinker, we investigated the degradation mechanism of CCPMs generated via both approaches using various analytical techniques. CCPMs based on complementary polymers degraded slower at pH 7.4 and 37 °C than CCPMs with a crosslinker (the half-life of the light scattering intensity was approximately 170 h versus 80 h, respectively). Through comparative analysis of the degradation profiles of the two different CCPMs, we conclude that partially ineffective intrachain crosslinks are likely formed using the small crosslinker, which contributed to more rapid CCPM degradation. Overall, this study shows that the type of crosslinking approach can significantly affect degradation kinetics, and this should be taken into consideration when developing new degradable CCPM platforms.

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Herein, a single molecule detection technology based on glass nanopore is established to analyze xylan dissolved in ionic liquid. The nanopore detection technology shows the structural difference of heterogenous branched chain and homogeneous straight chain based on the single characteristic current blocking signal and statistical information, providing a research basis for the structural analysis of water insoluble polysaccharides. More details are discussed in the article by He et al. on page 1720—1726.image

Chemoenzymatic and Synthetic Approaches To Investigate Aspartate- and Glutamate-ADP-Ribosylation.

We report here chemoenzymatic and fully synthetic methodologies to modify aspartate and glutamate side chains with ADP-ribose at specific sites on peptides. Structural analysis of aspartate and glutamate ADP-ribosylated peptides reveals near-quantitative migration of the side chain linkage from the anomeric carbon to the 2″- or 3″-ADP-ribose hydroxyl moieties. We find that this linkage migration pattern is unique to aspartate and glutamate ADP-ribosylation and propose that the observed isomer distribution profile is present in biochemical and cellular environments. After defining distinct stability properties of aspartate and glutamate ADP-ribosylation, we devise methods to install homogenous ADP-ribose chains at specific glutamate sites and assemble glutamate-modified peptides into full-length proteins. By implementing these technologies, we show that histone H2B E2 tri-ADP-ribosylation is able to stimulate the chromatin remodeler ALC1 with similar efficiency to histone serine ADP-ribosylation. Our work reveals fundamental principles of aspartate and glutamate ADP-ribosylation and enables new strategies to interrogate the biochemical consequences of this widespread protein modification.

Aging of biodegradable-mulch-derived microplastics reduces their sorption capacity of atrazine

Degradable plastics are gradually regarded as alternatives of conventional, synthetic organic polymers to reduce the plastics or microplastics (MPs) pollution; however, the reports upon environmental risk of degradable plastics are still limited. In order to evaluate the potential vector effect of biodegradable MPs on coexisting contaminants, sorption of atrazine onto pristine and ultraviolet-aged (UV) polybutylene adipate co-terephthalate (PBAT) MPs and polybutylene succinate co-terephthalate (PBST) MPs were investigated. The results showed that, UV aging led to more wrinkles and cracks on the surface, increased homogeneous chains proportion, enhanced hydrophobicity, and enlarged crystallinity of both MPs. The sorption kinetics of atrazine to MPs fitted well into pseudo-first-order (R2 = 0.809–0.996) and pseudo-second-order (R2 = 0.889–0.994) models. In the concentration range of 0.5–25 mg L−1, the sorption isotherm fitted into linear (R2 = 0.967–0.996) and Freundlich model (R2 = 0.972–0.997), indicating that the absorption partitioning was the dominant sorption mechanism. The partition coefficient (Kd) of atrazine to PBAT- MPs (40.11–66.01 L kg−1) was higher than that of PBST- MPs (34.34–57.96 L kg−1), and the Kd values of both MPs declined for aged MPs. The specific surface area, hydrophobicity, polarity and crystallinity of MPs jointly interpreted the changing sorption capacity of the MPs. In the present study, both aged PBAT- and aged PBST- MPs exhibited lower vector potential to atrazine than pristine MPs, suggesting reduced risk of being a pollutant carrier, which is of great significance for the development of biodegradable plastics.

On the Problem of Efficient Management of Homogeneous Products Supply Chains to Various Customers

he article considers the Logistics_SAP task which combines a number of subtasks that arise when fulfilling orders for some homogeneous products to various customers: managing the supply and purchase of the necessary raw materials for the manufactured products; inventory management; search for the optimal route of delivering products to various customers, taking into account their best placement in motor vehicles (MV). It is proposed that the listed subtasks should be integrated as an eXternal system into some modules in SAP to ensure efficient supply chain management with the orders for the manufactured products. Mathematical models, algorithms of the considered tasks and a real world eXample are provided in the article.

Optimal entanglement distribution policies in homogeneous repeater chains with cutoffs

We study the limits of bipartite entanglement distribution using a chain of quantum repeaters that have quantum memories. To generate end-to-end entanglement, each node can attempt the generation of an entangled link with a neighbor, or perform an entanglement swapping measurement. A maximum storage time, known as cutoff, is enforced on the memories to ensure high-quality entanglement. Nodes follow a policy that determines when to perform each operation. Global-knowledge policies take into account all the information about the entanglement already produced. Here, we find global-knowledge policies that minimize the expected time to produce end-to-end entanglement. Our methods are based on Markov decision processes and value and policy iteration. We compare optimal policies to a policy in which nodes only use local information. We find that the advantage in expected delivery time provided by an optimal global-knowledge policy increases with increasing number of nodes and decreasing probability of successful swapping.

Zero-mode entanglement across a conformal defect

We consider a free-fermion chain with a conformal defect that features an extended zero mode, and study the entanglement properties in its mixed ground state. The zero-mode induced degeneracy modifies the density of states in the single-particle entanglement spectrum, which can be calculated via the full counting statistics. For a homogeneous chain, the resulting change in the Rényi entropy is derived analytically for arbitrary subsystem ratios in the thermodynamic limit. For a conformal defect located in the center, analogous results can be obtained for the half-chain entanglement. In particular, we observe parity effects for half-chains with even/odd sites, which do not decay with size.