Ring Chain Research Articles

Comparison of Linear and Ring Polymers Partitioning into Pores Using Random Walks and Self‐Avoiding Walks Models

AbstractMonte Carlo simulations that examine the partitioning of dilute solutions of ring or linear chains into a slit pore using two chain models, the random‐walk (RW) model and the self‐avoiding walk (SAW) model are presented. The partitioning coefficients K for the ring and the linear chains at the surface interaction both under the critical adsorption point (CAP) and above the CAP are compared. In both chain models, K for the ring remains larger than K for the linear chains. The ring chain crosses over the point K = 1 at a weaker surface interaction than the linear chain. When extrapolated to infinite chain length, the cross‐over point for the ring and linear chain becomes the same (within statistical errors) for the RW model but remains different for the SAW model. The density profiles of the ring within the pore reveal the development of humps near the wall as the surface interaction crosses over the CAP. The excluded volume interaction in the SAW model additionally impacts the partitioning of chains in a solution consisting of a binary mixture of ring and linear chains and makes the K values in a binary mixture differ from the monodispersed solutions.

Ozone direct electro-generation/activation peroxymonosulfate (PMS) for the degradation of bisphenol A using Ti/NATO anode

In this study, Ni-doped Ti/SnO2-Sb anode (Ti/NATO) was prepared and used for electrocatalytic ozone production and in-situ activated peroxymonosulfate (E-Ti/NATO-PMS) to degrade bisphenol A (BPA). SEM, XRD and XPS results indicated that Ni doping could influence the transformations of Sb5+ and Sb3+ ions, which decreased the agglomeration of crystallites and increased the Oads and oxygen vacancy (Ov) concentrations. Ti/NATO1.0 anodes significantly improved the ozone production via outcompeting of the adsorbed O2ads over water, and inhibiting the desorption of O2ads, to obtain the highest O3 concentration with low onset potential and high oxygen evolution potential. E-Ti/NATO1.0-PMS system obtained over 92% BPA degradation within 60 min at 10 mA cm−2 and pH ranging from 4 to 10. Radical scavenging experiments revealed that O3in situ generated could directly electro-activate PMS into •O2− and 1O2. The E-Ti/NATO1.0-PMS process could detoxify the BPA through chain scission, rearrangement and ring opening processes, and exhibited great potentials for application.

On Hamming distance distributions of repeated-root constacyclic codes of length 3ps over [formula omitted

Let p≠3 be any prime. The algebraic structures of all λ-constacyclic codes of length 3ps over the finite commutative chain ring R=Fpm+uFpm are provided by classifying all ideals of the local ring R[x]〈x3ps−λ〉. Using these structures, in this paper, the exact values of Hamming distances of all such λ-constacyclic codes of length 3ps are established. As an application, we identify all maximal distance separable λ-constacyclic codes of length 3ps.

Dynamic Characteristics of the Chain Drive System under Multiple Working Conditions

The chain drive system, being one of the core subsystems of the scraper conveyor, greatly influences the coal-conveying efficiency due to its dynamic characteristics. Therefore, this paper employed an experimental method to compare the dynamic characteristics of the chain rings at various positions within the chain drive system. This article simulated the three most common working conditions. The results indicated that the chain speed, load, and surface undulation had a stimulating effect on chain vibration, with the most significant impact observed on the chain ring located in the middle of the adjacent scraper. The scraper exerted an inhibitory effect on the vibration of the chain ring. Among the factors studied, the load had the most significant influence on the transverse direction. When there was surface undulation, the vibration of the chain ring in the running direction formed an ‘N’ shape. This condition intensified the vibration during uphill and downhill stages while suppressing vibration at the slope peak. This research holds great significance in enhancing operation stability.

Insights from molecular dynamics into the chemistry-structure relationships of calcium aluminosilicate glasses

Calcium aluminosilicate (CAS) glasses are ubiquitous in nature and play an important role in diverse technological applications ranging from structural glasses to sustainable cementitious materials. Understanding the relationship between the chemical composition and the structure of CAS glasses is an essential step towards optimizing their properties for different uses in the future. Here, we use extensive molecular dynamics (MD) simulations to characterize the multiscale structure of CAS glasses over the full compositional range. Analysis of the short and medium range order of the glasses reveals that Lowenstein's rule is widely violated, that silica is more susceptible than alumina to the depolymerizing effects of calcium, and that high-silica glasses favor calcium in lower oxygen coordination states, while the opposite is true for high-alumina ones. We also find the presence of highly coordinated aluminum and tricluster oxygens in high-alumina glasses, which form as a charge compensation mechanism. We find that current theoretical models used to predict oxygen species, oxygen bridge types, or tetrahedral coordination, while overall qualitatively reasonable, simplify the complex interplay between the different oxides which results in inaccurate predictions, particularly for glasses in intermediate compositional regions. Our analysis of the cluster, chain, and ring topological structures in the aluminosilicate network reveals a sharp transition from a connected to a disconnected graph which depends not only on the calcium content of the glass, but also on the ratio of silica to alumina. Glasses in the compositional region corresponding to such transition display the largest ring and longest chain structures of any glass studied.

Kinetic study of hydrogen abstraction reactions from n-propyl/n-butylcyclohexane by hydrogen atom

Hydrogen abstraction reactions of alkylated cycloalkane by radicals play a fundamental role in combustion and atmospheric chemistry. In this work, we select two representative molecules in alkylated cycloalkane fuels, n-propylcyclohexane (nPCH) and n-butylcyclohexane (nBCH), to investigate the kinetics of their hydrogen abstraction reactions with hydrogen atom. The rate constants over a broad temperature range of 298–2000 K were calculated by using canonical transition state theory coupled with the multistructural torsional anharmonicity effect (TST/MS-T). We stress the particular importance of considering the MS-T anharmonicity for the investigated species involved in the H-abstraction pathways. Due to the approximate cancelation of the anharmonicity factor between the transition-state species and the reactant, the anharmonicity factors for reactions are spread over a narrower range of 0.7–3.3. The anharmonicity will slightly accelerate the H-abstraction for the nBCH system over the whole temperature range. The current results show that the multistructural torsional anharmonicity will influence the accurate estimation of competing relationships. We found that the total H-abstraction rate constants of the nBCH system by the TST/MS-T method are larger by factors of 1.2–1.3 than those for the nPCH system. The present data show that nPCH + H channels are less important by factors of 1.41–5.48 than currently estimated by the commonly used nPCH pyrolysis model. The H-abstraction ratios from the cyclic ring and side chain groups reveal that the rate rule for secondary carbon in chain alkanes does not represent the reactivity of all cycloalkanes well, e.g. the ratio between the cyclic ring and side chain group is high up to 2.8.

Electrochemical abatement of aquatic metoprolol by porous foam-titanium based metal oxide anodic membranes

Electrochemical membrane filtration (EMF) is a promising advanced oxidation technology for eliminating aquatic refractory pharmaceuticals. In this work, three porous foam-titanium based metal oxide (MOx) anodic membranes were prepared for comparison of their effectiveness against the model pharmaceutical pollutant metoprolol. The electrooxidation efficiencies of metoprolol by all flow-by operated anodic membranes were found to be elevated with increasing charging voltage and decreasing electrolyte solution pH, in which the PbO2 membrane exhibited more efficient metoprolol degradation efficiency over SnO2 and RuO2 membranes. At the chosen charging voltage of 2 V and electrolyte solution pH 7, compared to the flow-by mode, the higher total organic carbon (TOC) removal and less electrical energy consumption was achieved by the flow-through operated PbO2 membrane, ascribed to the enhanced mass-transfer of metoprolol and its intermediate by-products toward the anode surface. The physisorbed and free HO• produced by PbO2 membrane were found to be the key oxidants accounting for metoprolol degradation, which induced the transformation of metoprolol by attacking its benzene ring and side chains. Apart from the capacity for detoxifying metoprolol-containing influent, PbO2 membrane also exhibited favorable stability in flow-through mode. The study provides an effective strategy for the electrochemical remediation of pharmaceutical-polluted water and wastewater.

The Dynamic Behavior of a Single Semiflexible Ring Chain in a Linear Polymer Matrix

We studied the dynamic behavior of a single semiflexible ring in linear chain matrix based on a coarse-grained model using the molecular dynamics simulation approach. We found that that ring chains’ hollow centers are frequently filled with linear chains. However, as the rigidity of the linear chains increases, the linear chains arranged parallel to each other and the ring chain are temporary caged. As a result, the swing movement in the normal direction of the ring is significantly limited, and the relaxation time in the normal direction increases significantly. Our findings can help to understand the physical mechanism of the movement of the ring chain in ring–linear polymer blends at the microscopic level.

On Automorphisms of Chain Rings

Suppose R is a finite chain ring with invaraints p,n,r,k,k′,m. Suppose G is also the subset of all φ∈ Aut(R), the automorphism group of R, such that φ(πk′)=πk′, where π is a generator of the maximal ideal of R. It was found that G is a group that is, in some sense, the set of all symmetries of {πk′}. The main purpose of this article is to describe the structure of G. The subgroup G helps us understand the structure of Aut(R) in the general case which in turn provides immediate results in classifying chain rings.

Expanders on Matrices over a Finite Chain Ring, II

Expanders on Matrices over a Finite Chain Ring, II

Conformation and Dynamics of Ring Polymer Chains under Cylindrical Confinement

AbstractUsing coarse‐grained molecular dynamics simulations, the conformation and dynamic behavior of ring polymer chains in ring/linear blends confined into cylinders are studied. By changing the particle number density, polymer chain bending energy and length, the spatial distribution of rings in the constrained binary polymer blends is investigated. An ordered tubular structure composed of several quasi‐parallel rings is observed. The mean square displacement of the center‐of‐mass of ring chains and its diffusion coefficient are analyzed. The results indicate that the diffusion behavior of rings is transformed from inhibition to promotion as the increase of linear chain bending energy. This study provides a new way to further understand the special conformation and dynamic behavior of ring polymer chains in constrained systems.

In Silico Studies of Novel Vemurafenib Derivatives as BRAF Kinase Inhibitors

BRAF inhibitors have improved the treatment of advanced or metastatic melanoma in patients that harbor a BRAFT1799A mutation. Because of new insights into the role of aberrant glycosylation in drug resistance, we designed and studied three novel vemurafenib derivatives possessing pentose-associated aliphatic ligands—methyl-, ethyl-, and isopropyl-ketopentose moieties—as potent BRAFV600E kinase inhibitors. The geometries of these derivatives were optimized using the density functional theory method. Molecular dynamic simulations were performed to find interactions between the ligands and BRAFV600E kinase. Virtual screening was performed to assess the fate of derivatives and their systemic toxicity, genotoxicity, and carcinogenicity. The computational mapping of the studied ligand–BRAFV600E complexes indicated that the central pyrrole and pyridine rings of derivatives were located within the hydrophobic ATP-binding site of the BRAFV600E protein kinase, while the pentose ring and alkyl chains were mainly included in hydrogen bonding interactions. The isopropyl-ketopentose derivative was found to bind the BRAFV600E oncoprotein with more favorable energy interaction than vemurafenib. ADME-TOX in silico studies showed that the derivatives possessed some desirable pharmacokinetic and toxicologic properties. The present results open a new avenue to study the carbohydrate derivatives of vemurafenib as potent BRAFV600E kinase inhibitors to treat melanoma.

Minimal linear codes from defining sets over [formula omitted

Minimal codes are a special type of linear codes, which have nice applications in secret sharing and secure two-party computation. How to construct new infinite family of minimal codes has been a hot topic in coding theory and cryptography. In this paper, by employing exponential sums, we study the Lee-weight distributions of several classes of linear codes from defining sets over the finite chain ring Fp+uFp and determine exactly the complete weight enumerator of their Gray images under the Gray map. Furthermore, we prove that the Gray images of these linear codes are new infinite families of minimal five-weight linear codes with wminwmax<p−1p.

2D hydroxylated MXene (OH-MXene)/RGO composites modification toward superior electrocatalytic degradation of paracetamol

The MXene precursor was adjusted with a combination of –OH grafting and reduced graphene oxide (RGO) via alkalization and hydrothermal method to improve the electrocatalytic performance. The as-prepared hydroxylated MXene (OH-MXene)/RGO composites possess maximum 100 % paracetamol (APAP) degradation efficiency under an applied current of 15 mA, temperature of 25 °C, and electrolyte of 1 g/L NaCl. All characterization and experiment results showed that the grafting of –OH groups into MXene could access the active site of Ti-OH, strengthen the linking of OH-MXene and RGO layers (as C-Ti-Ox), accelerate the free electrons transfer from OH-MXene to RGO; thus, enhancing the catalytic activity of OH-MXene/RGO composites. Then, •OH, 1O2, O2•−, and active chlorine were determined as secondary active species in the solution, which dominated the APAP degradation. Three degradation pathways of APAP were further proven by gas chromatography-mass spectrum (GC–MS) with cleavage of N-branched chain and benzene rings. In addition, the superior and stable performance of OH-MG-15h under various operation conditions confirmed the application perspective of self-prepared material. The research not only provides feasible methods for MXene adjustment and electrocatalytic activity improvement but also proves its possibility for environmental application.

The weight distribution of codes over finite chain rings

In this work, we determine new linear equations for the weight distribution of linear codes over finite chain rings. The identities are determined by counting the number of some special submatrices of the parity-check matrix of the code. Thanks to these relations we are able to compute the full weight distribution of codes with small Singleton defects, such as MDS, MDR and AMDR codes.

Mechano Chemical Compatibilization of Polyethylene with Graphite by Means of a Suitable Ester.

An effective non-covalent compatibilization method for graphite and low-density polyethylene is reported. To obtain this result, pyren-1-yl-stearate (P1S) was synthesized, characterized and mixed with graphite to provide a better dispersion in polyethylene matrix. The P1S improves the dispersion of carbon filler in polyethylene through non-covalent compatibilization: the pyrenyl group gives π-π stacking interactions with graphite and the stearyl chain provides van der Waals interaction with the polymer chain (specifically London dispersion forces). In this study, different P1S/graphite fillers were prepared with a ratio by weight of 90/10 and 50/50, respectively, by using manual and ball-milling mixing. Their stability, interaction and morphology were evaluated through TGA, RX, and SEM. Thermogravimetric analyses showed that ball-milling mixing is more effective than manual mixing in promoting π-π stacking interactions of molecules such as P1S ester containing an alkyl chain and aromatic rings. The role of ball milling is confirmed by X-ray diffraction measurements since it was possible to observe both exfoliation and intercalation phenomena when this technique was used to mix the P1S ester with graphite. SEM analyses of polyethylene containing 1% of the carbon fillers again highlighted the importance of ball milling to promote the interaction of the ester with graphite and, simultaneously, the importance of the alkyl chain in order to achieve polyethylene-graphite compatibilization.

Two-dimensional assemblies of saccharide-derived molecules on highly oriented pyrolytic graphite revealed by scanning tunneling microscopy

Saccharides play important roles as structural components of plants and for molecular recognition in living organisms, and they are increasingly being used as environmentally-friendly bio-based materials. In this study, two-dimensional (2D) assemblies of 1,5-anhydro-D-glucitol (AG) derivatives were examined by scanning tunneling microscopy at the highly oriented pyrolytic graphite (HOPG)/solvent interface. The effects of the solvent, alkyl chain linkage, and alkyl chain length on the 2D structures were investigated. Grid-like and columnar structures were periodically formed depending on the odd–even nature of the carbon atoms in the alkyl chain unit, highlighting the importance of in-plane intermolecular interactions between adsorbed molecules in determining the 2D molecular arrangement. The calculated adsorption energies for the alkyl chain and pyranose ring units with the graphene model indicated that the former was significantly greater than the latter. Despite the strong interactions between adsorbates and substrate, relatively weak in-plane interactions between adsorbates result in the 2D molecular arrangements of the AG derivatives.

Dynamics of semiflexible ring polymer in chiral Brownian particles bath

Molecular dynamics simulations are used to investigate the dynamic behavior of ring polymer in a bath containing a high concentration of chiral Brownian particles. The chiral Brownian particles around the chain drive the ring polymer to deform, and torque acting on ring is produced and drive the ring to rotate in one direction. Furthermore, the relationship between the ring's rotation speed and the angular velocity of the surrounding Brownian particles is not monotonically linear. The rotation of the ring chain increases initially, then decreases as the angular velocity of the Brownian particle increases. These findings offer a theoretical framework for investigating the conformation and motion properties of polymer macromolecules in Brownian particle systems.

Dihydrocaffeic Acid-Is It the Less Known but Equally Valuable Phenolic Acid?

Dihydrocaffeic acid (DHCA) is a phenolic acid bearing a catechol ring and three-carbon side chain. Despite its being found in minor amounts in numerous plants and fungi of different origins, it has attracted the interest of various research groups in many fields of science, from food to biomedical applications. The review article presented herein aims to show a wider audience the health benefits and therapeutic, industrial, and nutritional potential of dihydrocaffeic acid, by sheddinglight on its occurrence, biosynthesis, bioavailability, and metabolism. The scientific literature describes at least 70 different derivatives of dihydrocaffeic acid, both those occurring naturally and those obtained via chemical and enzymatic methods. Among the most frequently used enzymes that were applied for the modification of the parent DHCA structure, there are lipases that allow for obtaining esters and phenolidips, tyrosinases used for the formation of the catechol ring, and laccases to functionalize this phenolic acid. In many studies, both in vitro and in vivo, the protective effect of DHCA and its derivatives on cells subjected to oxidative stress and inflammation were acknowledged.

Expanders on matrices over a finite chain ring, I

In this work and its sequel, we study the expanding phenomenon of matrices over a finite chain ring of large residue field. A sum-product estimate is proved. It is shown that [Formula: see text] is a moderate expander on [Formula: see text] matrices with exponent [Formula: see text]. These results generalize the main theorems in the recent work [29] of Xie and Ge. The proofs use spectral graph theory and elementary divisor theory.