Stable Ring Research Articles

High-Voltage-Tolerant Covalent Organic Framework Electrolyte with Holistically Oriented Channels for Solid-State Lithium Metal Batteries with Nickel-Rich Cathodes.

By introducing lithiophilic groups and electrochemically stable quinolyl aromatic ring linkages, we prepared covalent organic frameworks (COFs) exhibiting a large band gap with an ultralow HOMO value (-6.2 eV under vacuum) and oxidative stability up to 5.6 V (versus Li+ /Li) as solid-state electrolytes (SSEs). The obtained flexible COF SSE thin films showed a holistically oriented arrangement along the (001) facet with remarkable ionic conductivity up to 1.5×10-4 S cm-1 at 60 °C and excellent mechanical strength with a high Young's modulus of 10.5 GPa. Molecular dynamic simulations showed that lithium ions are transmitted in this COF SSE by directional hopping paths with fast drift velocity. The COF SSE film was used to assemble all-solid-state lithium metal batteries with nickel-rich cathodes (NMC811). The batteries demonstrated stable cycling performance over 400 cycles, high coulombic efficiency (>99 %), and could also withstand abuse tests, such as folding.

High‐Voltage‐Tolerant Covalent Organic Framework Electrolyte with Holistically Oriented Channels for Solid‐State Lithium Metal Batteries with Nickel‐Rich Cathodes

AbstractBy introducing lithiophilic groups and electrochemically stable quinolyl aromatic ring linkages, we prepared covalent organic frameworks (COFs) exhibiting a large band gap with an ultralow HOMO value (−6.2 eV under vacuum) and oxidative stability up to 5.6 V (versus Li+/Li) as solid‐state electrolytes (SSEs). The obtained flexible COF SSE thin films showed a holistically oriented arrangement along the (001) facet with remarkable ionic conductivity up to 1.5×10−4 S cm−1 at 60 °C and excellent mechanical strength with a high Young's modulus of 10.5 GPa. Molecular dynamic simulations showed that lithium ions are transmitted in this COF SSE by directional hopping paths with fast drift velocity. The COF SSE film was used to assemble all‐solid‐state lithium metal batteries with nickel‐rich cathodes (NMC811). The batteries demonstrated stable cycling performance over 400 cycles, high coulombic efficiency (>99 %), and could also withstand abuse tests, such as folding.

Nearly Gorenstein Rings Arising from Finite Graphs

The classification of complete multipartite graphs whose edge rings are nearly Gorenstein as well as that of finite perfect graphs whose stable set rings are nearly Gorenstein is achieved.

The initial expansion of the C. elegans syncytial germ line is coupled to incomplete primordial germ cell cytokinesis.

The C. elegans germline is organized as a syncytium in which each germ cell possesses an intercellular bridge that is maintained by a stable actomyosin ring and connected to a common pool of cytoplasm, termed the rachis. How germ cells undergo cytokinesis while maintaining this syncytial architecture is not completely understood. Here, we use live imaging to characterize primordial germ cell (PGC) division in C. elegans first-stage larvae. We show that each PGC possesses a stable intercellular bridge that connects it to a common pool of cytoplasm, which we term the proto-rachis. We further show that the first PGC cytokinesis is incomplete and that the stabilized cytokinetic ring progressively moves towards the proto-rachis and eventually integrates with it. Our results support a model in which the initial expansion of the C. elegans syncytial germline occurs by incomplete cytokinesis, where one daughter germ cell inherits the actomyosin ring that was newly formed by stabilization of the cytokinetic ring, while the other inherits the pre-existing stable actomyosin ring. We propose that such a mechanism of iterative cytokinesis incompletion underpins C. elegans germline expansion and maintenance.

Structures and Biological Activities of Diketopiperazines from Marine Organisms: A Review.

Diketopiperazines are potential structures with extensive biological functions, which have attracted much attention of natural product researchers for a long time. These compounds possess a stable six-membered ring, which is an important pharmacophore. The marine organisms have especially been proven to be a wide source for discovering diketopiperazine derivatives. In recent years, more and more interesting bioactive diketopiperazines had been found from various marine habitats. This review article is focused on the new 2,5-diketopiperazines derived from marine organisms (sponges and microorganisms) reported from the secondary half-year of 2014 to the first half of the year of 2021. We will comment their chemical structures, biological activities and sources. The objective is to assess the merit of these compounds for further study in the field of drug discovery.

Design, Synthesis, and Characterization of Novel sn-1 Heterocyclic DAG-Lactones as PKC Activators.

DAG-lactones represent useful templates for the design of potent and selective C1 domain ligands for PKC isozymes. The ester moiety at the sn-1 position, a common feature in this template, is relevant for C1 domain interactions, but it represents a labile group susceptible to endogenous esterases. An interesting challenge involves replacing the ester group of these ligands while still maintaining biological activity. Here, we present the synthesis and functional characterization of novel diacylglycerol-lactones containing heterocyclic ring substituents at the sn-1 position. Our results showed that the new compound 10B12, a DAG-lactone with an isoxazole ring, binds PKCα and PKCε with nanomolar affinity. Remarkably, 10B12 displays preferential selectivity for PKCε translocation in cells and induces a PKCε-dependent reorganization of the actin cytoskeleton into peripheral ruffles in lung cancer cells. We conclude that introducing a stable isoxazole ring as an ester surrogate in DAG-lactones emerges as a novel structural approach to achieve PKC isozyme selectivity.

Thermal crosslinking membrane with enhanced CO2 separation performance derived from nitrile-containing phenolphthalein-based poly(arylene ether ketone)

Enhancing gas permeabilities of thermal crosslinking membranes while retaining adequate selectivity is of great significance for industrial applications. In this work, a novel and commercial polymer of nitrile-containing phenolphthalein-based poly (arylene ether ketone) (PEK-C(CN)) was introduced to prepare thermal crosslinking membranes via pretreatment in air and subsequent thermal crosslinking treatment in N2, and the high permselectivity for CO2/CH4 and CO2/N2 gas pairs was achieved. The ATR-FTIR and XPS results demonstrated that the nitrile groups might undergo thermal cyclotrimerization reaction with the formation of stable triazine rings across molecular chains during the pretreatment, which is conducive to the preparation of defect-free and highly permeable thermal crosslinking membranes. During thermal crosslinking treatment, the Cardo moieties decomposed and induced crosslinking with forming bulky biphenyl linkages between polymeric chains, accompanied with pyrolysis of some nitrile groups, which resulted in an increase in interchain distance and microvoid size. The CO2 permeability of the resulting thermal crosslinking membrane was increased to around 3 times without sacrificing CO2/CH4 and CO2/N2 selectivities due to the incorporation of nitrile groups, compared to the thermal crosslinking membrane derived from nitrile-free PEK-C. For equimolar binary mixture gases, the fully crosslinked membranes present the CO2 permeability of around 1300 Barrer with CO2/CH4 and CO2/N2 separation factors of 32.6 and 35.8, respectively, which offer a promising alternative in CO2 capture and separation.

Human osteoclast formation and resorptive function on biomineralized collagen

Biomineralized collagen composite materials pose an intriguing alternative to current synthetic bone graft substitutes by offering a biomimetic composition that closely resembles native bone. We hypothesize that this composite can undergo cellular resorption and remodeling similar to natural bone. We investigate the formation and activity of human osteoclasts cultured on biomineralized collagen and pure collagen membranes in comparison to cortical bone slices. Human monocytes/macrophages from peripheral blood differentiate into multinucleated, tartrate-resistant alkaline phosphatase (TRAP)-positive osteoclast-like cells on all substrates. These cells form clear actin rings on cortical bone, but not on biomineralized collagen or pure collagen membranes. Osteoclasts form resorption pits in cortical bone, resulting in higher calcium ion concentration in cell culture medium; however, osteoclast resorption of biomineralized collagen and collagen membranes does not measurably occur. Activity of osteoclast enzymes – TRAP, carbonic anhydrase II (CA-II), and cathepsin-K (CTS-K) – is similar on all substrates, despite phenotypic differences in actin ring formation and resorption. The mesh-like structure, relatively low stiffness, and lack of RGD-containing binding domains are likely the factors responsible for preventing formation of stable actin rings on and resorption of (biomineralized) collagen membranes. This insight helps to guide further research toward the optimized design of biomineralized collagen composites as a more biomimetic bone-graft substitute.

Dynamically stable single frequency ring resonator from diode pumped Nd:YAG modules with 55.6 W of output power

A Nd:YAG rod single-frequency ring laser based on side-pumped commercial modules is presented. Thermally induced birefringence compensation was applied in a dynamically stable resonator providing 55.6 W of continuous, linearly polarized, TEM00 output. The particular case of a symmetric ring resonator containing one or two focusing rods and a pair of curved mirrors was analyzed and a design technique is presented, allowing for easy, continuous shaping of the stability limits by changing only the distances in the resonator.

Effects of different edge contacts on the photocatalytic and optical properties of blue phosphorene/arsenene lateral heterostructures

Recent advances in the synthesis and characterization techniques of atomic-scale thicknesses of crystals have enabled the fabrication of various two-dimensional lateral heterostructures (LHSs). In this paper, we systematically investigate the geometrical structures, electronic properties, band alignments, and optical properties of phosphorene/arsenene LHSs using first-principles calculations based on density functional theory. First, we constructed four stable phosphorene/arsenene LHSs with different edge contacts, named A–Z, Z–A, A–A and Z–Z phosphorene/arsenene LHSs. We then investigated the electronic structures of the different edge contacts. Interestingly, the calculated electron localization functions show that the most stable six-membered rings and previously reported five-membered and seven-membered rings are formed at the interface of the blue phosphorene/arsenene LHSs. Moreover, the band edge alignments and optical absorption properties show that A–A and Z–A phosphorene/arsenene LHSs have band-edge conditions suitable for photocatalytic water decomposition, which provides a possibility for their application in the area of photocatalytic water decomposition. These results provide a route for applications of these heterostructures in future optoelectronic and semiconductor devices, and also pave the way for the design of new blue phosphorene/arsenene LHSs and the exploration of their potential applications in optoelectronic devices.

Practical and Computational Studies of Bivalence Metal Complexes of Sulfaclozine and Biological Studies.

In the search for novel, metal-based drug complexes that may be of value as anticancer agents, five new transition metal complexes of sulfaclozine (SCZ) with Cu(II), Co(II), Ni(II), Zn(II), and Fe(II) were successfully synthesized. The chemical structure of each complex was characterized using elemental analysis (CHN), IR spectroscopy, UV–Vis spectroscopy, thermogravimetric analysis (TGA), and electronic paramagnetic resonance (EPR) spectroscopy. IR spectra indicated that the donor atoms were one sulfonyl oxygen atom and one pyrazine nitrogen atom, which associated with the metal ions to form a stable hexagonal coordination ring. The metal–ligand stability constant (Kf) revealed that Cu(II) and Ni(II) have good coordination stability among the metal compounds. Theoretical studies using DFT/B3LYP were performed to further validate the proposed structures. The obtained results indicated that Cu(II) has a trigonal bipyramidal geometry, whereas Fe(II), Co(II), and Ni(II) have an octahedral structure, while Zn(II) has a tetrahedral arrangement. The bio-activities of the characterized complexes were evaluated using DNA binding titration and molecular docking. The binding constant values for the metal complexes were promising, with a maximum value for the copper metal ion complex, which was 9 × 105 M-1. Molecular docking simulations were also carried out to evaluate the interaction strength and properties of the synthesized metal complexes with both DNA and selected cancer-relevant proteins. These results were supported by in vitro cytotoxicity assays showing that the Cu(II) and Ni(II) complexes display promising antitumor activity against colon and breast cancer cell lines.

An essential role of the autophagy activating kinase ULK1 in snRNP biogenesis.

The biogenesis of small uridine-rich nuclear ribonucleoproteins (UsnRNPs) depends on the methylation of Sm proteins catalyzed by the methylosome and the subsequent action of the SMN complex, which assembles the heptameric Sm protein ring onto small nuclear RNAs (snRNAs). In this sophisticated process, the methylosome subunit pICln (chloride conductance regulatory protein) is attributed to an exceptional key position as an ‘assembly chaperone’ by building up a stable precursor Sm protein ring structure. Here, we show that—apart from its autophagic role—the Ser/Thr kinase ULK1 (Uncoordinated [unc-51] Like Kinase 1) functions as a novel key regulator in UsnRNP biogenesis by phosphorylation of the C-terminus of pICln. As a consequence, phosphorylated pICln is no longer capable to hold up the precursor Sm ring structure. Consequently, inhibition of ULK1 results in a reduction of efficient UsnRNP core assembly. Thus ULK1, depending on its complex formation, exerts different functions in autophagy or snRNP biosynthesis.

Three-dimensional-printed custom-made hemipelvic endoprosthesis for the revision of the aseptic loosening and fracture of modular hemipelvic endoprosthesis: a pilot study

BackgroundThe aims of this pilot study were (1) to assess the efficacy of 3D-printed custom-made hemipelvic endoprosthesis in restoring the natural location of acetabulum for normal bodyweight transmission; (2) to evaluate the short-term function of the revision with this endoprosthesis and (3) to identify short-term complications associated with the use of this endoprosthesis.MethodsBetween February 2017 and December 2017, seven patients received revision with 3D-printed custom-made hemipelvic endoprosthesis. The body weight moment arm (BWMA) and cup height discrepancy (CHD) after primary and revisional surgery were analyzed to assess acetabulum location with plain radiography. After a median follow-up duration of 29 months (range 24–34), the function was evaluated with the Musculoskeletal Tumor Society (MSTS-93) score and Harris hip score (HHS). Complications were recorded by chart review.ResultsThe acetabulum locations were deemed reasonable, as evaluated by median BWMA (primary vs. revision, 10 cm vs. 10 cm) and median CHD (primary vs. revision, 10 mm vs. 8 mm). The median MSTS-93 score and HHS score were 21 (range 18–23) and 78 (range 75–82) after the revision. No short or mid-term complication was observed in the follow-up of this series.ConclusionsRevision with 3D-printed custom-made hemipelvic endoprostheses benefited in reconstructing stable pelvic ring and natural bodyweight transmission for patients encountering the aseptic loosening and fracture of modular hemipelvic endoprosthesis. The revision surgery and appropriate rehabilitation program improved patients’ function to a median MSTS score of 22 and pain-free ambulation. The incidence of the complications was low via this individualized workflow.

On the arithmetic of stable domains

A commutative ring R is stable if every non-zero ideal I of R is projective over its ring of endomorphisms. Motivated by a paper of Bass in the 1960s, stable rings have received wide attention in the literature ever since then. Much is known on the algebraic structure of stable rings and on the relationship of stability with other algebraic properties such as divisoriality and the 2-generator property. In the present paper, we study the arithmetic of stable integral domains, with a focus on arithmetic properties of semigroups of ideals of stable orders in Dedekind domains.

A comparative study for phosphate adsorption on amorphous FeOOH and goethite (α-FeOOH): An investigation of relationship between the surface chemistry and structure

Eutrophication is generally caused by excess nitrogen and phosphorus being released into surface waters by runoff. Developing adsorbents for adsorbing phosphate within soil buffer zones and/or water treatment columns may be effective methods to mitigate this problem. In this study, an amorphous FeOOH (AF) and a well-crystallized α-FeOOH (CF) was formulated to compare phosphate adsorption behavior. The physicochemical properties between these species showed significant differences in morphology, crystallization, zeta potential, and specific surface area. The AF exhibited higher phosphate uptake than CF. X-ray photoelectron spectroscopy (XPS) verified that the hydroxyl groups within AF were 13.28% higher than that in CF. The triply coordinated hydroxyl groups (μ3-OH) associated with AF and CF appeared at different positions as shown in the diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analyses, confirming that AF contains more adsorption reactive sites (μ3-OH). Mechanisms for monodentate formations and a stable six-member ring structure were proposed. The X-ray absorption near the edge structure (XANES) and XPS results suggested that the iron valence in AF was dominated by Fe (III). XANES also demonstrated that the amorphous structure found in the AF was caused by the disordered tetrahedron and octahedron alignments, leading to a higher phosphate adsorption.

Perspective of Zn3O3 ring cluster via density functional theory

ZnO is well known for its optical properties and broad application. Although it has been investigated extensively, information regarding Zn3O3 clusters in the form of a ring is insufficient. This paper discusses the extraction of a ZnO ring as a Zn3O3 cluster comprising three molecules obtained from a 2 × 2 × 2 zincite supercell and its optimized normal, cationic, and anionic forms under the density functional theory framework. Its geometric and electronic structures as well as electronically excited states are investigated based on electronic spectra. Furthermore, the density of states, transition densities of molecular orbitals, highest and lowest occupied molecular orbitals, lowest unoccupied molecular orbitals, gap energies, binding energies, ionization potential, electron affinity, and quantum descriptors are investigated. Significant changes in the ultraviolet (UV)–visible absorption spectra are reported based on time-dependent density functional theory. Weak interactions by non-covalent interactions in Zn3O3 are investigated for the first time in this study; variations in the electrostatic potential are also discussed. The stable form ring and its formation are investigated using thermodynamic potentials U, H, and G (with additional parameters such as zero-point energy and entropy), which are obtained through frequency optimization. The rings investigated from the Zn3O3 cluster suggest some possibilities, such as the tuning of UV to visible light absorption.

Development of fluorescent-labeled trapping reagents based on cysteine to detect soft and hard electrophilic reactive metabolites

Trapping assays are conducted at lead optimization stages to detect reactive metabolites (RMs) that can contribute to drug toxicity. The commonly used dansyl glutathione (dGSH) provides a sensitive analysis owing to the fluorescent label, however, it captures only soft electrophilic RMs. TRs for hard electrophilic RMs, few of which are labeled fluorescently, can detect hard electrophilic aldehydes only by forming unstable imine derivatives. In this study, we aimed to develop novel fluorescently labeled TRs that detect both soft and hard electrophilic RMs and form stable ring structures with aldehydes. We designed four dansylated TRs based on cysteine, which has both soft and hard nucleophilic groups. To evaluate the reactivity of the TRs, we incubated them with several substrates and found that one of the TRs (CysGlu-Dan) detected all the soft and hard electrophilic RMs. We also examined the inhibition potential of each TR for seven major CYPs involved in drug metabolism and found that CysGlu-Dan showed an inhibitory profile similar to that of dGSH. In conclusion, CysGlu-Dan can be used to evaluate the risk of RMs in drug discovery.

Photocatalytic Oxygenation of Heterostilbenes—Batch versus Microflow Reactor

On the basis of earlier results with furan and thiophene derivatives of benzobicyclo[3.2.1]octadiene, photocatalytic oxygenation of novel furo- and thieno heterostilbenes with water-soluble manganese(III) porphyrins offered suitable possibilities to study their reactivities and reaction pathways depending on the heteroatom and the catalyst charge. The experiments were carried out in two reactors types (batch and microflow) to investigate the geometric effects. NMR spectroscopy, GC, and UPLC/MS analyses were applied for identification and quantification of the products. As our results indicated, the 2-thienyl and the common p-tolyl groups in the starting compounds remained intact due to their stronger aromaticity. Hence, the thieno derivative underwent oxygenation only at the open-chain part of the molecule, and the rates of its reactions were much lower than those of the furyl analogue. The less stable furan ring was easily oxygenated, its products with highest ratios were 2-furanon derivatives. Epoxide formation occurred at the open-chain parts of both substrates preferably by the anionic catalyst. Nevertheless, the conversion rates of the substrates were higher with the cationic porphyrin, according to electrophilic attacks by photogenerated Mn(V)=O species. Additionally, the reactions were significantly faster in microflow reactors due to the more favorable circumstances of mass transfer, diffusion, and light penetration.

Signet ring cell carcinoma of rectum metastasizing to synchronous renal cell carcinoma: a case report

BackgroundRectal signet ring cell carcinoma is a rare type of colorectal adenocarcinoma characterized by an aggressive biological behavior and poor prognosis. The co-occurrence of colorectal carcinoma and renal cell carcinoma (RCC) has found in many hundreds of patients, many of whom also have additional malignancies. Cancer to cancer metastasis is rare and an uncommon phenomenon in malignancy, especially at the time of initial diagnosis, suggesting a genetic susceptibility.Case presentationWe present the case of a 66-year-old Macedonian man with synchronous rectal signet ring cell carcinoma and RCC with tumor to tumor metastasis feature. He underwent a left nephrectomy and anterior rectal resection after complaining of constipation for 3–4 months and the appearance of synchronous tumors on the imaging studies. Morphology and immunohistochemical analysis of specimens from the RCC revealed signet ring cells identical to the rectal signet ring cell carcinoma. The next-generation sequencing study revealed mutations in TP53 and ERBB2, and microsatellite stable signet ring cell carcinoma was determined by deoxyribonucleic acid (DNA) sequencing.ConclusionsCancer to cancer metastasis, although rare, needs to be considered in synchronous tumors. RCC, when diagnosed in multiple synchronous tumors, should be examined carefully. The paucity of reported cases indicates the need for advanced research in imaging methods for metastasis and new therapeutic approaches.

Crystal structure of P. falciparum Cpn60 bound to ATP reveals an open dynamic conformation before substrate binding

Plasmodium falciparum harbors group 1 and group 2 chaperonin systems to mediate the folding of cellular proteins in different cellular locations. Two distinct group 1 chaperonins operate in the organelles of mitochondria and apicoplasts, while group 2 chaperonins function in the cytosol. No structural information has been reported for any chaperonin from plasmodium. In this study, we describe the crystal structure of a double heptameric ring Plasmodium falciparum mitochondrial chaperonin 60 (Cpn60) bound with ATP, which differs significantly from any known crystal structure of chaperonin 60. The structure likely represents a unique intermediate state during conformational conversion from the closed state to the opened state. Three of the seven apical domains are highly dynamic while the equatorial domains form a stable ring. The structure implies large movements of the apical domain in the solution play a role in nucleotide-dependent regulation of substrate binding and folding. A unique 26–27 residue insertion in the equatorial domain of Plasmodium falciparum mitochondrial chaperonin greatly increases both inter-ring and intra-ring subunit–subunit interactions. The present structure provides new insights into the mechanism of Cpn60 in chaperonin assembly and function.