Ring Type Research Articles

Molecular Model Construction and Optimization Study of Gas Coal in the Huainan Mining Area

To construct the macromolecular model of gas coal in the Huainan mining area, 13C nuclear magnetic resonance spectroscopy (13C-NMR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) tests were used to analyze the microstructure characteristics of coal including the aromatic ring type, the linkage mode, and the chemical bonding composition. The model was simulated and optimized by molecular mechanics (MM) and molecular dynamics (MD). The experimental results showed that the coal macromolecular formula in the Huainan mine was expressed as C181H150O9N3. The aromatic ring was dominated by anthracene and phenanthrene. Aliphatic carbon mainly existed in the form of methylene and methine. The oxygen atoms existed in the form of ether−oxygen bonds. The ratio of pyridine nitrogen to pyrrolic nitrogen was 2:1. The molecular simulation results showed the π−π interaction between the aromatic lamellae within the molecule. The van der Waals energy was the major factor of coal molecular structure stability and energy change. The results of the calculated 13C-NMR carbon spectrum and density simulation agreed well with the experimental results. The study provides a scientific and reasonable method for coal macromolecular model prediction and theoretical support for coal spontaneous combustion prevention technology.

Jewish Wedding Rings with Miniature Architecture from Medieval Europe

Among the various types of medieval rings, Jewish wedding rings with miniature architecture have a special significance due to their special form, their importance in the Jewish wedding ceremony and their long tradition that extends from the Middle Ages into present day. This paper will examine their function in the wedding ceremony and their role as part of marriage as a legal transaction and the symbolism of their particular design.

Synthesis of Hybrid Epoxy Methacrylate Resin Based on Diglycidyl Ethers and Coatings Preparation via Cationic and Free-Radical Photopolymerization

A series of difunctional epoxy methacrylate resins (EAs) containing at least one epoxy and at least one methacrylate group were synthesized by means of an addition reaction between epoxy-terminated diglycidyl ethers and methacrylic acid. In order to investigate the impact of polymer architecture on the course of addition reactions and further coating properties, several different types of diglycidyl ethers, i.e., linear, containing aliphatic or aromatic rings, with a short or polymeric backbone, were employed in the synthesis. The carboxyl-epoxide addition esterification reactions have been found to, in a relatively straightforward manner, control the extent of acrylation depending on the substrate feed ratio and reaction time. The structure of obtained pre-polymers was evaluated by FT-IR and NMR methods. At the same time, the extent of addition reactions was validated via quantitative analysis, including non-volatile matter content (NV), acid value (PAVs), and epoxy equivalent value (EE) analysis. The modification was carried out in a manner likely to create a compound with one epoxy and one carbon-carbon pendant group. Hence, due to the presence of both functionalities, it is possible to crosslink compositions based on synthesized EAs via two distinct mechanisms: (i) cationic polymerization or (ii) free-radical polymerization. Synthesized epoxy methacrylate pre-polymers were further employed for use in formulate photocurable coating compositions by the cationic or radical process. Furthermore, the photopolymerization behavior and properties of cured coatings were explored regarding some structural factors and parameters. The investigated polymeric materials cure in a short time to obtain coatings with good properties, which is why they can be successfully used to produce protective and decorative coatings for many industries.

Assembly of Diverse [60]Fullerene-Fused Tricyclic Scaffolds via a Palladium-Catalyzed Cascade [2 + 2 + 2] Annulation Reaction.

Herein, a concise and robust approach for the highly efficient assembly of [60]fullerene-fused tricyclic scaffolds has been developed through a palladium-catalyzed cascade [2 + 2 + 2] annulation process. Diverse tricyclic scaffolds incorporating various ring sizes (6-19 membered) and types (carbocycles and N- and O-heterocycles) can be expediently constructed in a single-step transformation.

Molecular simulations of liquid aliphatic carboxylic acids (C1-C6) using the 3D-RISM-KH molecular solvation theory

The liquid structures of short straight chain aliphatic carboxylic acids (C1-C6) and halogenated acetic acids (trifluoro and trichloro) are analyzed with molecular dynamics simulations, three-dimensional reference interaction site model, and density functional theory calculations. The neat acids are found to exist in multimeric ordered form consisting of both open chain and cyclic oligomers. Introduction of water breaks the hydrogen bonding networks between adjacent acetic acid molecules by inserting water as a bridging molecule. The electronic structure calculations confirm the formation of chain and ring type structures in the liquid state.

Mitral valve surgery assisted by virtual and augmented reality: Cardiac surgery at the front of innovation.

Given the variety in mitral valve (MV) pathology and associated surgical techniques, extended reality (XR) holds great potential to assist MV surgeons. This review aims to systematically evaluate the currently available evidence investigating the use of XR and associated technologies in MV surgery. A systematic database search was conducted of original articles and case reports that explored the use of XR and MV surgery in EMBASE, MEDLINE, Cochrane database and Google Scholar, from inception to February 2022. Our search yielded 171 articles, of which 15 studies were included in this review, featuring 328 patients. Two main areas of application were identified: (i) pre-operative planning and (ii) predicting post-operative outcomes. The articles reporting outcomes relating to pre-operative planning were further categorised as exploring themes relevant to (i) mitral annular assessment; (ii) training; (iii) evaluation of surgical technique; (iv) surgical approach or plan and (v) selecting ring size or type. Preoperatively, XR has been shown to evaluate mitral annular pathology more accurately than echocardiography, informing the surgeon about the optimal surgical technique, approach and plan for a particular patient's MV pathology. Furthermore, XR could simulate and aid ring size/type selection for MV annuloplasty, creating a personalized surgical plan. Additionally, XR could estimate the postoperative MV biomechanical and physiological characteristics, predicting and pre-empting post-operative complications. XR demonstrated promising applications for assisting MV surgery, enhancing outcomes and patient-centred care, nevertheless, there remain the need for randomized studies to ascertain its feasibility, safety, and validity in clinical practice.

Construction of [2,5]-Furanophanes by Carbene-Mediated Alkynyl Migration Cyclization

Heterophanes are widely found in natural products and drug molecules. Herein, an efficient method for the construction of [2,5]-furanophanes with different ring types and ring sizes was developed. This method is carried out with furan-free precursor through intramolecular carbene-mediated alkynyl migration and tandem cyclization strategy. In addition, a series of tetrafuran structures can be obtained by oxidative coupling of the products.

Control Techniques for Interconnections of Cluster of Neighboring Islanded Hybrid Smart Microgrids

This paper presents an architecture for interconnections of cluster of neighboring islanded mix smart microgrids (both DC and AC), for sharing the power among various areas. The cluster of microgrids consists of three microgrids i.e. two DC microgrids operating at different voltages and one AC microgrid. All microgrids have ring type architectures, which consist of various renewable distributed generations, battery energy storage systems, and various AC and DC loads. Two DC microgrids are interconnected through the bidirectional DC–DC converter, and the DC microgrid and AC microgrid are interconnected through the bidirectional single-phase voltage source converter (VSC). In this work, the control techniques of the bidirectional VSCs, used for interconnections of three microgrids, have also been developed, for controlling the operation of the interconnected microgrids system. The developed control techniques use the feed-back and feed-forward control signals. The developed control techniques are aimed to manage the bidirectional power flow between the interconnected microgrids, and to maintain constant desired rated voltages of all microgrids, under islanded mode, for different operating conditions. To verify the robustness of the proposed interconnected microgrids system and developed control techniques, the simulations are carried out under various operating scenarios, in the MATLAB environment.

BC2N nanotube as a promising anode for rechargeable calcium ion batteries

Because of cost-effective production and abundant resources of calcium, Ca-ion batteries (CIBs) are an appropriate option to alternate Li-ion batteries (LIBs). A new category of anode materials for CIBs has emerged since the successful synthesis of carbon nanotubes, which are B and N doped derivatives of it. For high-performance CIBs, BC2N nanotube (BC2NNT) has been studied as promising anode materials. In order to comprehend electrochemical attributes, cycling stability, and adsorption behavior of BC2NNT, first-principles computations have been executed. Based on nuclear magnetic resonance computations, two types of hexagonal rings (B2C2N2 (I) and BC4N (II)) were specified that are non-aromatic. Ca has adsorption on B2C2N2 and BC4N with adsorption energy (Ead) values of −47.44 and −28.50 kcal/mol, respectively. Specific capacity value has been determined to be as high as 840 mAh/g. The predicted average open-circuit voltage (OCV) for BC2NNT is 1.56 V, which has a larger value than that of other 2D materials. All mentioned reasons provide BC2NNT as an acceptable anode material for use in CIBs. In present research, results may create new ways of designing favorable boron-carbon-nitrogen based anode materials for CIBs.

S3700 Role of Immunotherapy in the Treatment of Recurrent Hereditary Diffuse Gastric Cancer

Introduction: Gastric cancer is the third leading cause of cancer related deaths worldwide. Majority of cases are sporadic although 10% demonstrate familial clustering, of which 1-3% arise from inherited cancer syndromes. Hereditary diffuse gastric cancer is a rare cancer caused by CDH1 genetic mutation, inherited in an autosomal dominant fashion. Immunotherapy has been shown to increase overall response rates in gastrointestinal cancers especially in those subgroups with DNA mismatch repair-deficient or microsatellite-instable tumors. We herein, present a case of recurrent hereditary diffuse gastric cancer with good response to chemoimmunotherapy. Case Description/Methods: This is a 41-year-old asian female with past medical history of stage IIB signet ring type gastric cancer diagnosed 12 years ago, status post subtotal gastrectomy with a block transverse colectomy followed by concurrent chemoradiation, who presented with disease recurrence after 10 years, when she was treated with neoadjuvant 5-fluorouracil based chemotherapy followed by surgical resection and adjuvant chemotherapy. Her genetic screening showed CDH1 mutation, with high risk for breast and gastric cancers. She was monitored closely with regular breast magnetic resonance imaging (MRI) and esophagogastroduodenoscopy (EGD). During one of her regular endoscopy assessments recently, she was found to have erythema of her gastric mucosa which upon biopsy confirmed recurrence of her poorly differentiated adenocarcinoma, diffuse type with signet ring features. She underwent treatment with oxaliplatin based chemotherapy combined with Nivolumab for six cycles. She responded well to chemoimmunotherapy as evidenced by positron emission tomography and computed tomography (PET CT) scan and esophagogastroduodenoscopy (EGD). She is awaiting surgical resection followed by adjuvant therapy with chemotherapy either alone or in combination with immunotherapy. Discussion: Gastrectomy and chemotherapy are the mainstay treatments for hereditary diffuse gastric cancer. Nivolumab has been shown to be effective in heavily pretreated gastric cancers. The combination therapy of nivolumab plus chemotherapy achieved a clinically meaningful overall survival benefit in the first line setting in all advanced gastric adenocarcinoma. Clinical trials and research encompassing antibody treatments, such as targeted anti-PD1 antibodies, are ongoing and could offer additional treatment options in patients with advanced gastric cancer.

IR, UV-visible, NMR spectra and aromaticity of the covalent organic tetraoxa[8]circulene frameworks

In this paper, we explore the aromaticity, electronic, vibrational and NMR spectra of the novel tetraoxa[8]circulene-based covalent organic frameworks which were first synthesized in 2022 [Angew. Chem. Int. Ed. 61 (2022) e202116527] being predicted by quantum chemical modeling in 2014 [Phys. Chem. Chem. Phys. 16 (2014) 6555–6559]. Both studied 2x2 and 3x3 tetraoxa[8]circulene (TOC) oligomers represent polyaromatic systems consisting of 108π (2x2) and 168π (3x3) electrons in the outer perimeter with a global diatropic (“aromatic”) current; they includes also two types of internal rings: the cyclooctatetraene cores with 8π electrons and larger C16(CH4)O4 cavities with 28π electrons. Both internal rings provide local paratropic (“antiaromatic”) ring currents.The elongated π-conjugated system of the 2x2 and 3x3 TOC oligomers is responsible for the unique nature of photoinduced charge transfer and vibrational spectra, which obey strict selection rules within the D4h symmetry point group. The nature of photoinduced charge transfer was interpreted using visualization methods including charge density difference and transition density matrix. It was found that strong optical absorption around 500 nm is for the doubly degenerated S3(4) (1Eu) states, in which one pair of oppositely located anthracene fragments has an alternating distribution of holes and electrons, while in the other pair of anthracene fragments, the holes and electrons are mainly localized on the central benzene fragments and the ethylene bridges of adjacent furan rings, respectively. For both 2x2 and 3x3 TOC oligomers, the optical absorption strength for S1 and S2 states is vanished. The density functional calculations of 2x2 and 3x3 TOC models have also allowed us to make the assignment of all the observed lines in the IR and Raman spectra of experimental pTOC samples. We believe that the TOC oligomers represent a new-generation of macrocyclic host molecules in heterocirculene and supramolecular chemistry.

Factors affecting apparent survival and resighting probability of wintering mallards Anas platyrhynchos

Survival of adults is a key demographic parameter affecting avian population dynamics. In urban areas, e.g., city parks, birds stay in winter in large numbers where they have access to a multitude of food sources due to human activities, which is one of the key factors that attract birds into the cities. Our study estimates apparent survival of mallard ducks Anas platyrhynchos between non-breeding seasons in a small town in the coldest region in north-eastern Poland between 2005 and 2017. We found lower survival estimates for females (juveniles: 0.54; adults: 0.59) than males (juveniles: 0.76; adults: 0.72) and probabilities of resighting individuals in the next non-breeding season were higher if the bird was resighted in the study area during the prior breeding period. Thus, we conclude that sedentary mallards from the local urban population have relatively high survival, which may be explained by lower pressure from raptors, lack of hunting and higher winter temperatures in the urban site. Additionally, winter temperature was negatively related to resighting probability in the next non-breeding season. Resighting probability was time-dependent with a bimodal pattern with maximal estimates of 0.48 in 2007/2008 and 0.98 in 2013/2014, 0.98 in 2014/2015, 1.00 in 2015/2016. These results are most likely related to volunteers’ activity that increased due to organized official competition with special awards during those seasons. Considering the fact that the type of ring (metal or plastic coloured) significantly influenced the probabilities of resighting of individuals, it is recommended that apparent survival studies on birds be conducted using colour rings. Moreover, we encourage to collect more capture-mark-recapture data to enable accurate estimations of duck survival, which not the least is a prerequisite for successful management and conservation efforts.

Contact analysis and performance evaluation of ring type traveling wave ultrasonic motors based on a surface contact model

A surface contact model of ring type traveling wave ultrasonic motors is proposed in this paper in order to describe the circular three-dimensional contact and friction problem between the stator and rotor accurately. Differing from previous contact models of traveling wave ultrasonic motors, the flexibility of the rotor, which results in the irregular shape of contact area and inhomogeneous distribution of contact pressure along radial direction, is taken into account in the proposed model. The normal contact between the stator and rotor is analyzed with finite element method and the tangential force transmission on the contact surface is investigated with analytical method. The contact pressures and the tangential stresses on the contact surface are obtained. Mechanical performances of the motor are also studied based upon the proposed model. Finally, torque-speed curves of a prototype motor are measured and compared with the calculated results of the proposed model, and good agreements are obtained. In addition, the proposed surface contact model is compared with previous line contact models. It is found that the calculated results of the surface contact model are closer to measured results than those of line contact models. The comparison results verify the accuracy of the proposed surface contact model.

Cooperativity and fragility in furan-based polyesters with different glycolic subunits as compared to their terephthalic counterparts

This works aims to investigate the effect of the molecular groups found in polyester backbones (type of ring in the acidic subunit and length of the glycolic subunit) on the molecular dynamics. The investigation is done on three furan-based polyesters (PEF, PPF and PBF) as compared to their terephthalic counterparts (PET, PTT, and PBT) after full quenching from the molten state. The segmental molecular dynamics is investigated with MT-DSC, FSC and DRS. It is shown that the cooperativity decreases as the length of the glycolic subunit increases in both furan-based and terephthalic polyesters. No direct correlation between the fragility index and the cooperativity is observed in furan-based polyesters containing glycolic subunits of different lengths. The differences in the isochoric fragilities obtained for the furan-based polyesters and their terephthalic counterparts has been assumed to result from the combination of backbone flexibility and packing efficiency of the macromolecular chains in the amorphous phase.

Double Aortic Arch as a Rare Condition in a 10-year-old Boy with Recurrent Pneumonia: A Case Report Study

Introduction: A double aortic arch (DAA) is a congenital anomaly of the aortic arch, which is also the most common type of complete vascular ring. This vascular ring can compress the trachea and esophagus, as well as cause respiratory, gastrointestinal, and cardiac symptoms. Case Presentation: In the present case report, a 10-year-old boy with recurrent cough, fever, shortness of breath, chest pain, and a history of recurrent respiratory infections was examined. According to the results of bronchoscopic evaluation, he was found to have a localized tracheomalacia. DAA and dextrocardia condition were also confirmed for this patient by performing a computed tomography angiography of the thorax and the three-dimensional reconstruction of CT angiography. Conclusions: The diagnosis of double aortic arch may be confused with upper respiratory tract infections or foreign body aspiration. Therefore, it was recommended that a particular attention should be paid to the double aortic arch when evaluating cases of stridor in children with unknown causes or recurrent respiratory infections. CT angiography and cardiac MRI were the diagnostic methods of choice for examining vascular rings.

A biorenewable cyclobutane-containing building block synthesized from sorbic acid using photoenergy

SummaryA novel cyclobutane-containing diacid building block, CBDA-3, was synthesized from sorbic acid using clean, efficient [2 + 2] photocycloaddition. This photoreaction can be performed using commercially available germicidal lamps, which represent a form of ECO-UV. SC-XRD showed that the cyclobutane ring in CBDA-3 has a unique semi-rigid character, unlike more rigid aromatic rings or more flexible types of aliphatic rings. C=C bonds present in the structure of CBDA-3 provide opportunities for derivatization which could be used to alter the characteristics of polymers made from this monomer. Additionally, TGA and DSC analysis showed CBDA-3 to have excellent thermal stability. These characteristics make CBDA-3 a promising building block with the potential to be used as a sustainable alternative to traditional petroleum-derived diacids. Finally, a facile and reliable Fischer esterification of CBDA-3 was performed to tune its melting point and solubility for different applications and to demonstrate the applicability of this building block in polymer synthesis.

374 Thoracotomy vs Video-assisted Thoracoscopic Surgery in the Treatment of Vascular Rings

Abstract Aim This review aims to investigate the procedure itself, post-operative complication rates and long-term outcomes of both VATS procedures and thoracotomy procedures in the treatment of VRs. Method A literature search of the MEDLINE and SCOPUS databases were performed at the projects inception to present. From the 361 articles retrieved, 271 were excluded. After applying the exclusion criteria and thorough manual screening, 14 studies were included in the review. 6 of these studies investigated the outcomes using thoracotomy, 3 case reports plus 2 studies that investigated the outcomes using VATS and 3 studies that directly compared the two procedures. All 11 studies were retrospectively performed with 4 studies collecting data for over 20 years, 2 studies over 10 years and the remaining studies collected data for 2–8 years. Results Overall, 590 cases in this review focused on using thoracotomy operations and 190 cases used VATS. The main themes from the results of the literature included: type of vascular ring identified, case and collection period of the studies, the surgical approach, post-operative complications, length of stay in hospital, symptom resolution, reoperation rates and mortality. In this review, VATS demonstrated reduced length of stay in hospital, lower reoperation rates and a lower mortality rate than the thoracotomy studies. The results indicated similar rates in operating time and rates of post-operative complications between the two procedures. Conclusions This review provides insight into the encouraging outcomes in the use of VATS compared to the thoracotomy cases which is the gold standard approach in vascular ring surgery.

Controlled Living Cascade Polymerization of Polycyclic Enyne Monomers: Leveraging Complete Degradability for a Stereochemical and Structural Investigation.

Cascade polymerizations recently gained significant attention due to their use of unique transformations, involving multiple bond making and/or breaking steps, when converting monomers to repeat units. However, designing complex cascade polymerizations which proceed in a controlled manner is very challenging. Various side reactions can hamper polymerization performance and the efficiency of the cascade. In this work, we explore a metathesis-based cascade polymerization of unique polycyclic enyne monomers, which contain a terminal alkyne and two cyclic alkenes. By modifying the monomer's stereochemistry, linkers, and ring types, we were able to modulate the polymerization performance and the extent to which a complete cascade reaction occurs. Upon subjecting the resulting polymers to mild acidic conditions and analyzing the degradation products, we were able to calculate the percentage of repeat units derived from a complete cascade reaction (termed the cascade efficiency). In addition to identifying how various structural parameters in the monomer influence the success of a cascade polymerization, we were able to achieve controlled living cascade polymerizations of multiple monomers with >99% cascade efficiency and produce various block copolymers.

Design and Performance Analysis of Micropump for Drug Delivery Using Normal and Stacked Ring Type Piezoelectric Actuator

Design and Performance Analysis of Micropump for Drug Delivery Using Normal and Stacked Ring Type Piezoelectric Actuator

Local atomic structure evolution of liquid gadolinium and yttrium during solidification: An ab initio study

Local atomic structure evolution of pure gadolinium (Gd) and yttrium (Y) during solidification was investigated by using ab initio molecular dynamics (AIMD) simulation. The calculated results indicate that the local short-range order (SRO) in liquid Gd and Y is similar to some transitional metals with an asymmetric shape of the second peak in static structure factors. Moreover, the formation of icosahedral local motifs as a function of temperature decreases the diffusivity, which explains the connection between structure evolution and dynamic properties. In examining the topological structures of both systems, we demonstrate that small atomic displacement leads to two different types of topological sixfold rings in liquid and solid states. All analyses yield a systematic study about rare earth metals Gd and Y at the atomic level.