Stable Ring Research Articles

Detoxification of Plant Aromatic Abietanoids via Cleavage of the Benzene Ring into 11,12-Seco-diterpene Polyenes by a Specialist Insect of Leucosceptrum canum.

Leaves of Leucosceptrum canum harbor abundant toxic aromatic abietanoids, and they are rarely attacked by insect herbivores, except for the larvae of Nacna malachitis. The excrements of the insect that fed on L. canum leaves were investigated, leading to the isolation and identification of two unprecedented 11,12-seco-abietane diterpene polyenes: nacnabietanins A (1) and B (2). This discovery heralds a unique detoxification mechanism of plant aromatic abietanoids by insects through enzymatic cleavage of stable benzene rings into more easily degraded polyenes.

Permanent-Charge Generation Derivatization for the Analysis of Thiols by “Soft” Ionization Mass Spectrometry Methods

A new method is proposed for the permanent-charge generation derivatization of thiols of different structures by a reaction with haloalkanes and dibromides. It was shown that 1,4-dibromobutane and 1,2-xylylene dibromide are the most effective alkylating agents, providing the formation of a stable five-membered ring with a positively charged sulfur atom. Such cations are readily detected by electrospray ionization and matrix-assisted laser desorption/ionization mass spectrometry. Sulfonium cations were further studied by tandem mass spectrometry using collision-induced dissociation (CID). Typical and specific CID directions for cyclic cations formed from thiols of different structures are revealed. They can be used to identify and quantify thiol analytes by the selected reaction monitoring method.

Synthesis of TiB₂ Powders with Hexagonal Morphology by Sol-Gel Method.

TiB₂ powders were successfully synthesized by carbothermal reduction of Ti-C-O-B precursor in argon at 1450 °C for 2 h. And the Ti-C-O-B precursor was formed by sol-gel method using titanium butyrate (Ti(OC₄H9)₄), fructose (C6H12O6), boric acid (H₃BO₃), and acetyl acetone (acac). Furthermore, thermogravimetric analysis-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), Raman, scanning electron microscope (SEM) and energy dispersive spectrum (EDS) were employed to analyze and characterize the precursor and TiB₂ powders. Here, acac as stabilizer was studied using FITR when it reacted with Ti(OC₄H9)₄ and the stable six-member ring was formed in order to prevent the nucleophilic attack of water, which reduced the hydrolysis rate of Ti(OC₄H9)₄. Besides, the composition of TiB₂ phase was tested by the Raman spectra, and the results showed that the peaks at 263 cm-1, 410 cm-1, and 598 cm-1 were ascribed to the characteristic peaks of TiB₂. Finally, the photomicrograph revealed TiB₂ powders with a hexagonal morphology and the average grain size of TiB₂ particles was ca. 1 um. The EDS indicated that the particles contain elements of Ti and B according to dot and line scan.

A density functional theory perspective on 2,2,9,9‐tetrahalostannacyclonona‐3,5,7‐trienylidenes

AbstractCompared with cyclonona‐3,5,7‐trienylidene (1H), which turns out as a boat‐shaped singlet transition state for having a negative force constant, its heavier stanylenic analogues (2X), where X = H, F, Cl, Br, and I, emerge as boat‐shaped minima. This unsubstituted carbene has triplet ground state while exclusive of 2I, which initially take on a triplet multiplicity and eventually transforms to a less stable intramolecular ring opening product; other stanylenes (2H, 2F, 2Cl, and 2Br) have singlet ground state. Hence, stability anticipated by the singlet‐triplet splitting (ΔES‐T) decreases by going down in group 17 column: 2Br > 2Cl > 2F > 2H > 2I > 1H. Also, the HOMO‐LUMO energy separation (ΔEHOMO‐LUMO) increases as a result of substituting. The main stabilizing effect appears to be π– and σ–bond hyperconjugation among the iodine hetero atom and divalent center of triplet 2I. From a thermodynamic perspective, our scrutinized 2Br, 2Cl, and 2F are found 1.5 to 2 times more stable than that of the reported cyclopenta‐2,4‐dienstanylene and 2,5‐bis (halobora)‐cyclopentenstanylene analogues. From a kinetic perspective, these nine‐membered stanylenes are found 10 to 18 kcal/mol more stable than that of their corresponding five‐membered congeners. The NBO analysis on stable singlet 2Br‐S shows that there is a three‐type interaction including the first interaction between its bromine's lone pairs and tin's 5pπ orbital (mesomeric effect), second interaction between its bonding orbital (σCα‐Br) and tin's 5pπ orbital (positive hyperconjugation), and third interaction between its σ2Sn occupied orbital and antibonding orbitals of σ*Cα‐Br (negative hyperconjugation).

Extraction combined catalytic oxidation desulfurization of petcoke in ionic liquid under mild conditions

The desulfurization of high-sulfur petcoke under mild condition is a great challenge due to the structurally stable aromatic ring skeleton with a large steric hindrance of sulfur compounds. Herein, by using polyoxometalate ionic liquid [Bmim]3PW12O40 and H2O2 as catalyst and oxidant, respectively, the sulfur content in the petcoke was reduced from 4.46 wt% to 2.85 wt% in green solvent [Bmim]BF4. Moreover, the reaction performed at a mild temperature (80 °C), significantly lower than that in the industrial methods (≥1700 °C). It realized the conversion of high-sulfur petcoke from waste to resources. The experimental results indicated that sulfides in petcoke were oxidized to sulfate, sulfone and sulfoxide, while SO2 was not produced in the process of desulfurization. The possible oxidative desulfurization mechanism was proposed based on the series of characterizations.

Uranium determination in industrial effluents by voltammetric method using triazene 1-oxide as an alternative binder

This study reports for the first time the uranium (U) determination in industrial effluents by differential pulse adsorptive stripping voltammetry using triazene compound as a binder. Analyses were performed in 0.01 mol L−1 acetate buffer (pH 4.4), and the binder used was 1-methyl-3-(p-carboxyphenyl)triazene 1-oxide with the complex reduction peak at − 0.38 V. A detection limit of 0.06 and a quantification limit of 0.20 µg L−1 were achieved. The recovery values of spiked samples were between 80 and 100% (RSD less than 10.4%), and the concentration range from 0.35 to 7 μg L−1 was linear (r2 = 0.99). The values of U quantified in the samples INB-01, INB-02, INB-03 and INB-04 were 10.74, 30.58, 58.21 and 956.56 μg L−1, respectively. The complex formed is irreversibly reduced on the electrode surface, with the transfer of two electrons, and the process is controlled by diffusion. Additionally, it is suggested that the U(VI) center coordinates itself to the N and O atoms of six triazene groups forming stable five-membered rings with coordination number equal to twelve and icosahedral geometry.

Identification of hsa_circ_0001821 as a Novel Diagnostic Biomarker in Gastric Cancer via Comprehensive Circular RNA Profiling.

Background: The morbidity and mortality of gastric cancer (GC) remain high worldwide. With the advent of the Human Genome Sequencing Project, circular RNAs (circRNAs) have attracted widespread attention in cancer research due to their stable ring structure. Our aim was to identify differentially expressed circRNAs in GC and explore their potential roles in GC diagnosis, treatment, and prognostic prediction.Methods: Large-scale gene screening was performed in three pairs of GC tissues and adjacent noncancerous tissues using high-throughput sequencing. The expression of hsa_circ_0001821 was detected in 80 pairs of tissue samples by quantitative real-time PCR (qRT-PCR). Stability of the ring structure of hsa_circ_0001821 RNA was verified by exonuclease digestion assay, and its diagnostic value was evaluated by receiver operating characteristic (ROC) analysis. In addition, the location of hsa_circ_0001821 in GC cells was detected by nucleoplasm separation assay.Results: A total of 25,303 circRNAs were identified, among which 2,007 circRNAs were differentially expressed (fold change > 2.0, P < 0.05). Further validation disclosed that hsa_circ_0001821 was significantly downregulated in the 80 pairs of GC tissues and 30 whole-blood specimens obtained from the GC patients. The specificity of hsa_circ_0001821 in GC was higher than that in other solid tumors. In addition, hsa_circ_0001821 was relatively stable after RNA exonuclease digestion. Clinicopathological parameter analysis showed that hsa_circ_0001821 was negatively correlated with tumor depth (r = −0.255, P = 0.022) and lymph node metastasis (r = −0.235, P = 0.036). Area under the curve (AUC) analysis showed that the diagnostic efficiency of circulating hsa_circ_0001821 in distinguishing GC patients was higher than that in GC tissues (0.872, 95%CI: 0.767–0.977 vs. 0.792, 95%CI: 0.723–0.861). Combined use of circulating hsa_circ_0001821 with the existing tumor markers yielded the largest AUC of 0.933. Finally, hsa_circ_0001821 was demonstrated to mainly locate in the cytoplasm, implying that it played a potential regulatory role in GC at the posttranscriptional level.Conclusion: Hsa_circ_0001821 may prove to be a new and promising potential biomarker for GC diagnosis.

Universal deformation rings of finitely generated Gorenstein-projective modules over finite dimensional algebras

Let k be a field of arbitrary characteristic, let Λ be a finite dimensional k-algebra, and let V be a finitely generated Λ-module. F. M. Bleher and the third author previously proved that V has a well-defined versal deformation ring R(Λ,V). If the stable endomorphism ring of V is isomorphic to k, they also proved under the additional assumption that Λ is self-injective that R(Λ,V) is universal. In this paper, we prove instead that if Λ is arbitrary but V is Gorenstein-projective then R(Λ,V) is also universal when the stable endomorphism ring of V is isomorphic to k. Moreover, we show that singular equivalences of Morita type (as introduced by X. W. Chen and L. G. Sun) preserve the isomorphism classes of versal deformation rings of finitely generated Gorenstein-projective modules over Gorenstein algebras. We also provide examples. In particular, if Λ is a monomial algebra in which there is no overlap (as introduced by X. W. Chen, D. Shen and G. Zhou) we prove that every finitely generated indecomposable Gorenstein-projective Λ-module has a universal deformation ring that is isomorphic to either k or to k〚t〛/(t2).

Role of Multidetector Computed Tomography with Three Dimension Reconstruction in Evaluation of Pelvic Fractures.

AbstractBackground: Pelvic fracture is a serious injury that may be associated with high morbidity and mortality. MDCT is more frequently used for accurate evaluation of pelvic fractures.Aim of Study: The aim of this work is to evaluate the role of multidetector CT with three dimension reconstruction in diagnosis of pelvic fractures.Patients and Methods: This prospective study included 70 patients who presented with pelvic fractures and referred from outpatient clinics of Orthopedic Department to the Radiology and Medical Imaging Department, Tanta University Hospital. The present study was performed in the period between February 2018 and March 2019. Their ages ranged from 4 to 82 years; 45 of them were males and 25 were females. All cases underwent multidetector computed tomog-raphy as a rapid, noninvasive diagnostic tool, and the findings were compared with those of plain X-ray.Results: According to our results patients with partial stable pelvic ring fractures (Tile type B) had higher incidence than stable fractures (54.28%), followed by stable Tile A fractures (28.57%). Young Burgess lateral compression frac-tures had significantly higher incidence (68.57%) especially Young Burgess subtype LC1 (54.28%). All sacral fractures were associated with pelvic ring fratures, Denis zone I was the most common (54.28%). The elementary Judet-Letournel acetabular fractures were the most common (58.82%) espe-cially type posterior wall (20.58%). Hip dislocations and femur head fractures were rare, represented only by 4 cases for each. The most common hip dislocation type was the posterior dislocation represented only by 2 cases (50%).Conclusion: MDCT with 3D has numerous advantages and accurate in diagnosis of pelvic fratures.

Silver(I) complexes with long-chain diamines in non-aqueous solvents

The results of a potentiometric and calorimetric study on the complexation reactions of neutral N-donor ligands 1,4-diaminobutane (dab) and 1,5-diaminopentane (dap) with silver(I) in dimethylsulfoxide (DMSO) are reported. The investigation is extended for dab ligand to the aprotic solvent acetonitrile (AN), which presents quite different dielectric constant and donor number with respect to DMSO. In both solvents, polynuclear Ag2L22+ and Ag2L32+ species of high stability are formed, which inhibit the formation of mononuclear ones. The Ag2L22+ species are stabilized by the formation of large, stable non-chelate cyclic rings whose structures are described by DFT calculations. The overall enthalpy terms associated with the complex formation are strongly exothermic, whereas entropy values oppose the complex formation. An interesting feature is the little enthalpy and no significant or positive entropy variation associated with the successive formation of Ag2L32+. Also in this case, molecular modeling studies shed some light on their structure in solution, indicating that probably no changes of configuration around the metal ion occur. The stability constants and enthalpy values obtained for common Ag2L22+ species are slightly influenced by the chain length of the diamines, as confirmed also by a comparison with available data for the same species formed by the shorter 1,3-diamino propane (dapr) in DMSO.

Experimental generation of a flat-top beam profile in a stable ring cavity.

In this Letter, we present a spatially homogeneous field inside of a ring cavity that was created by combining two transverse modes generated by a single laser through modulation. The interference term between the two modes averages out because of the frequency difference that exists between them, eliminating the need for interferometric control of their relative phase. The use of a ring cavity allows for a large waist for the flat-top profile, big enough to cover the atoms in an atomic trap. The cavity is mechanically and thermally isolated, and the laser light is locked to the cavity using the Pound-Drever-Hall technique. The flat-top profile technique reported here fulfills the vanishing curvature criterion at the center of the profile.

Self-Toughening and Self-Enhancement Poly(arylene ether nitrile) with Low Dielectric Constant by Solid Crosslinking Reaction.

A novel poly(arylene ether nitrile) terminated with hydroxyl groups (PEN–OH) was synthesized successfully. The effects of heat-treatment temperature on the thermal properties, mechanical properties, and dielectric properties of the PEN–OH films were studied in detail. Due to the cross-linking reaction occurring, at high temperature, among the nitrile groups on the side of the PEN–OH main chain to form a structurally stable triazine ring, the structure of materials changes from a linear structure to a bulk structure. Thus, the thermal properties and mechanical properties were improved. In addition, the occurrence of cross-linking reactions can reduce the polar groups in the material, leading to the decrease of dielectric constant. As the heat-treatment temperature increased, the glass-transition temperature increased from 180.6 °C to 203.6 °C, and the dielectric constant decreased from 3.4 to 2.8 at 1 MHz. Proper temperature heat-treatment could improve the tensile strength, as well as the elongation, at the break of the PEN–OH films. Moreover, because of the excellent adhesive property of PEN–OH to copper foil, a double-layer flexible copper clad laminate (FCCL) without any adhesives based on PEN–OH was prepared by a simple hot-press method, which possessed high peel strength with 1.01 N/mm. Therefore, the PEN–OH has potential applications in the electronic field.

Water Clusters in Lignite and Desorption Energy Calculation by Density Functional Theory.

The interaction of water and hydrophilic sites with hydroxyl, carboxyl, and multiple oxygen-containing functional groups (OFGs) in lignite molecules was studied by density functional theory. The adsorption of water molecules on the lignite surface initially resulted in the formation of hydrogen bond-driven stable rings by three to four water molecules, followed by the formation of three-dimensional water clusters like a ″patchwork″. Aqueous layer thickness obtained from the water cluster size was 0.4–0.6 nm, which was consistent with the experimental data. Thus, pore-filling water beyond this range was less affected by the OFGs on the surface. Calculation of the adsorption energy predicts that the water clusters were primarily formed in the hydrophilic sites with three OFGs (site 1, including a carbonyl group, an alcoholic hydroxyl group and an etheroxy group in tetrahydropyran), then in COOH, and in O–H. For isolated hydroxyl groups, the interaction between the hydroxyl group and water molecules was weaker than that between the water molecules. When the water cluster was located at the hydrophilic sites with two or more OFGs, the adsorption energy of lignite–water interaction was higher than that of water–water interaction. Investigating the thermodynamics of the adsorption process at a molecular scale will help in understanding both drying and resorption process of dried lignite during industrial production.

Delay performance due to thermal variation on field‐programmable gate array via the adoption of a stable ring oscillator

Thermal issues are rapidly evolving in the field-programmable gate arrays (FPGAs) and are being intensely studied as these issues appear to significantly affect the delay performance of FGPAs. A ring oscillator has been widely used as a digital temperature sensor to sense this thermal effect on FPGAs. The delay generated by the ring oscillator will vary depending on the temperature environment due to negative bias temperature instability, hot carrier injection and electromigration. It is therefore critical to adopt an accurate ring oscillator design to effectively measure the delay in FGPAs. In this study, a digital temperature sensor with a stable ring oscillator is proposed. Measurement periods of 512 and 4096 clock cycles have been implemented and the relationship between temperature, delay and total count has been established. The results show that as the temperature increases to 100°C, the delay decreases by 3.99 and 33.98% for 512 and 4096 clock cycles, respectively. It has been found that in order to reduce the degradation effect on the Virtex-6 FPGA, adopting a measurement period of 512 clock cycles is the best method. The measured data is successfully validated through a set of simulations. Thus, it may benefit a system designer and industrial player, especially in designing temperature-based FPGAs.

Analysis of individual molecular dynamics snapshots simulating wetting of surfaces using spheroidal geometric constructions

Accurate characterization of wettability of minerals is important for efficient oil recovery and carbon geosequestration. In studies where molecular dynamics simulations are used to compute the contact angle, emphasis is often placed on results or theoretical details of the simulations themselves, overlooking potentially applicable methodologies for determination of the contact angle. In this manuscript, a concept of a method utilizing spheroidal geometric constructions to estimate the contact angle of a water droplet on a silica surface in carbon dioxide atmosphere is outlined and applied to the final snapshots of two molecular dynamics simulation runs. Two carbon dioxide pressures and two wettability modes (hydrophilic and hydrophobic) are examined to assess the method’s performance. The most stable 6-membered ellipselike rings (001) pristine surface of alpha-quartz is reconstructed using molecular dynamics and its wettability is then investigated for the first time. The outcomes of the calculations are compared with results produced with the isodensity chart method, and good agreement with the latter approach is demonstrated. The proposed method can be used as an alternative, or in conjunction with other techniques, to increase the confidence in contact angle estimations via molecular mechanics calculations. Reliable contact angle estimations, on the other hand, can guarantee accurate storage capacity and security of carbon capture and storage projects.

Optically thin outbursts of rotating neutron stars cannot be spherical

Abstract We investigate 3D relativistic trajectories of test particles in the spacetime of a slowly rotating compact star, under the combined influence of gravity and a strong, near-Eddington radiation field. While in the static case a spherically symmetric shell of matter suspended above the stellar surface can be formed at the location of radial equilibrium of effective forces, the same is not true for a rotating star. In the latter case the symmetry is broken by the interplay between motion in the non-static spacetime and the influence of strong radiation drag forces, pushing particles towards the equatorial plane. As a result an expanding spherical shell of matter ejected from the neutron star surface collapses on a short time-scale into a single stable equatorial ring supported by radiation. These findings have implications for the geometry of optically thin outflows during luminous neutron star bursts.

Geographical variation and the response to hydrothermal factor of stable carbon isotope (δ13C) in Pinus massoniana.

We used 10 representative provenances at different latitudes in two 33-year-old Pinus massoniana provenance test stands (Chun'an Laoshan in Zhejiang and Taizi Mountain Shilong in Hubei) to measure the differences among provenances, study the geographical variation, and identify its responses to hydrothermal factors. The results showed that the δ13C of the average annual rings was significantly different among the provenances of P. massoniana, being higher in trees from high latitude than from low latitude. The δ13C of average annual rings showed a zonal variation trend, indicating an adaptation to the original environment. The δ13C of annual rings was negatively correlated with mean annual temperature (MAT), mean temperature in January (T1), annual precipitation (MAP), precipitation from May to September (P5-9) and cumulative temperature above 10 ℃ (CT). It was positively correlated with the aridity index (AI). The response function of AI toδδ13C annual rings in Chun'an and Taizi Mountain explained 37.5% and 42.5% of the variation, respectively, indicating that AI was the most important limiting factor. The Taizi Mountain test site in Hubei Province located in the central and western region with relatively dry soil and high aridity. Therefore, the δ13C of the average annual ring was 1.8% higher than that in the Chun'an test site. The δ13C rings of P. massoniana at the Taizi Mountain and Chun'an were sensitive to the temperature in July and August, respectively. Summer precipitation was the main factor for carbon isotope fractionation with stable rings. The sensitivity of different provenances to future climate changes was different.

Rho-dependent control of the Citron kinase, Sticky, drives midbody ring maturation.

Rho-dependent proteins control assembly of the cytokinetic contractile ring, yet it remains unclear how those proteins guide ring closure and how they promote subsequent formation of a stable midbody ring. Citron kinase is one important component required for midbody ring formation but its mechanisms of action and relationship with Rho are controversial. Here, we conduct a structure–function analysis of the Drosophila Citron kinase, Sticky, in Schneider’s S2 cells. We define two separable and redundant RhoGEF/Pebble-dependent inputs into Sticky recruitment to the nascent midbody ring and show that each input is subsequently required for retention at, and for the integrity of, the mature midbody ring. The first input is via an actomyosin-independent interaction between Sticky and Anillin, a key scaffold also required for midbody ring formation. The second input requires the Rho-binding domain of Sticky, whose boundaries we have defined. Collectively, these results show how midbody ring biogenesis depends on the coordinated actions of Sticky, Anillin, and Rho.

Highly Specific Cys Fluorescence Probe for Living Mouse Brain Imaging via Evading Reaction with Other Biothiols.

Depression is characterized by oxidative stress in the brain. As the crucial reductive biothiol, cysteine (Cys) directly regulates the occurrence of oxidative stress in the brain. Despite its significance, the precise exploration of Cys in mouse brains remains a challenge, primarily owing to the limitations of Cys-monitoring tools, especially the interference from unavoidable reaction with other biothiols. Thus, we developed a novel two-photon fluorescence probe for Cys based on a new specific recognition site, thiobenzoate. Encountering Cys, the carbon-sulfur double bond in the probe formed a stable five-membered ring via the selective nucleophilic addition reaction, triggering a remarkable fluorescence increase. Notably, this reaction cannot occur with other biothiols, which afford the probe unprecedented selectivity to Cys. With two-photon excitation at 754 nm, we achieved in situ visualization of the increased Cys in PC12 cells under dithiothreitol stimulation. Furthermore, we directly visualized the precipitous reduction of Cys in the brains of mice with depression phenotypes for the first time. This work opens up new vistas for Cys imaging and expands the understanding of pathogenesis of depression.

Universal deformation rings of string modules over certain class of self-injective special biserial algebras

We determine the universal deformation rings of string -modules whose corresponding stable endomorphism ring is isomorphic to and which lie either in a connected component of the stable Auslander-Reiten quiver of containing a module with endomorphism ring isomorphic to or in a periodic component containing only string -modules, where and are integers, and is a self-injective special biserial -algebra.