Number Of Rings Research Articles

Energy gap and aromatic molecular rings.

The manuscript combines rational density functional theory simulations and experimental data to investigate the electrical properties of eight polycyclic aromatic hydrocarbons (PAHs). The optimized geometries reveal a preference for one-row, two-row and three-row ring distributions. Band structure plots demonstrate an inverse correlation between the number of aromatic rings and band gap size, with a specific order observed across the PAHs. Gas phase simulations support these findings, though differences in values are noted compared to the literature. Introducing a two-row ring distribution concept resolves discrepancies, particularly in azulene. The B3LYP function successfully bridges theoretical and experimental gaps, particularly in large PAHs. The manuscript highlights the potential for designing electronic devices based on different-sized PAHs, emphasizing a multi-ring distribution approach and opening new avenues for practical applications.

Novel integrated structure and function of Mg–Gd neutron shielding materials

Abstract As the lightest metal structural materials, magnesium (Mg) alloys offer extensive application potential. Gadolinium (Gd), as the primary alloying element in Mg alloys and recognized for its notable thermal neutron capture cross-section, is considered one of the most efficient neutron absorbers. Thus, the Mg–Gd alloy is highly expected to emerge as a material with remarkable neutron absorption capacity. Hence, in this study, the thermal neutron-shielding capabilities of Mg–Gd alloys were comprehensively examined by fabricating four as-cast Mg–xGd alloys with varying compositions (x = 0, 5, 10, and 15 wt%). The obtained results were further corroborated by sophisticated modeling and calculations using SuperMC. The results revealed a direct correlation between the thermal neutron absorption capacity of the Mg–Gd alloys and the increase in Gd content, with a noteworthy neutron attenuation factor of 22.33. Moreover, in an Au ion irradiation experiment conducted at 200°C, the Mg–15Gd alloy exhibited exceptional radiation resistance, with a displacement per atom (dpa) of 10. The matrix and second-phase regions were devoid of any cavity formation. Instead, a finite number of dislocation rings were observed, forming both leaf-like and granular Gd-rich nanoscale precipitates. This study underscores the versatility of Mg–Gd alloys as efficient neutron shielding materials and structural materials tailored for applications demanding radiation resistance in diverse environments.

Single-molecule analysis of solvent-responsive mechanically interlocked ring polymers and the effects of nanoconfinement from coarse-grained simulations.

In this study, we simulate mechanically interlocked semiflexible ring polymers inspired by the minicircles of kinetoplast DNA (kDNA) networks. Using coarse-grained molecular dynamics simulations, we investigate the impact of molecular topological linkage and nanoconfinement on the conformational properties of two- and three-ring polymer systems in varying solvent qualities. Under good-quality solvents, for two-ring systems, a higher number of crossing points lead to a more internally constrained structure, reducing their mean radius of gyration. In contrast, three-ring systems, which all had the same crossing number, exhibited more similar sizes. In unfavorable solvents, structures collapse, forming compact configurations with increased contacts. The morphological diversity of structures primarily arises from topological linkage rather than the number of rings. In three-ring systems with different topological conformations, structural uniformity varies based on link types. Extreme confinement induces isotropic and extended conformations for catenated polymers, aligning with experimental results for kDNA networks and influencing the crossing number and overall shape. Finally, the flat-to-collapse transition in extreme confinement occurs earlier (at relatively better solvent conditions) compared to non-confined systems. This study offers valuable insights into the conformational behavior of mechanically interlocked ring polymers, highlighting challenges in extrapolating single-molecule analyses to larger networks such as kDNA.

Regulating Benzene Ring Number as Connector in Covalent Organic Framework for Boosting Photosynthesis of H2O2 from Seawater.

Photosynthesis of H2O2 from seawater represents a promising pathway to acquire H2O2, but it is still restricted by the lack of a highly active photocatalyst. In this work, we propose a convenient strategy of regulating the number of benzene rings to boost the catalytic activity of materials. This is demonstrated by ECUT-COF-31 with adding two benzene rings as the connector, which can result in 1.7-fold enhancement in the H2O2 production rate relative to ECUT-COF-30 with just one benzene ring as the connector. The reason for enhancement is mainly due to the release of *OOH from the surface of catalyst and the final formation of H2O2 being easier in ECUT-COF-31 than in ECUT-COF-30. Moreover, ECUT-COF-31 provides a stable photogeneration of H2O2 for 70 h, and a theoretically remarkable H2O2 production of 58.7 mmol per day from seawater using one gram of photocatalyst, while the cost of the used raw material is as low as 0.24 $/g.

Efficacy of pesticides against Nesidiocoris tenuis Reuter (Hemiptera: Miridae), an emerging threat in the cultivation of tomato in Northwest Europe

As non-chemical methods are not always effective to manage pests, the search for chemical solutions that efficiently combat pest species, while safeguarding the environment and beneficial organisms, is essential for advancing effective Integrated Pest Management (IPM) programs. Here, we investigated the efficacy of commercially available pesticides in managing Nesidiocoris tenuis, an emerging threat in the cultivation of tomato in Northwest Europe, while preserving the biocontrol agent Macrolophus pygmaeus. Fourteen pesticides were assessed for their residual toxicity on adults and nymphs in laboratory experiments, after which the most promising candidate was evaluated in cages and semi-commercial greenhouse conditions. Among the pesticides tested, chlorantraniliprole, hexythiazox, tebufenozide and azadirachtin had minimal impact on both insect species, with less than 37.5% corrected mortality. Pirimicarb, sulfoxaflor, acetamiprid, flupyradifurone, thiacloprid, tebufenpyrad, spinosad, indoxacarb, and a mixture of pyrethrins and piperonyl butoxide were harmful to N. tenuis, but also affected M. pygmaeus (up to 100% mortality). Emamectin benzoate was moderately effective to N. tenuis adults (87%) and nymphs (80%), but had limited effects on M. pygmaeus. Application of emamectin benzoate at the maximum recommended concentration resulted in a significantly higher mortality of N. tenuis adults (85%) compared to M. pygmaeus (53%) in cage experiments, while it significantly reduced N. tenuis nymphs and the number of necrotic rings in a greenhouse experiment. Emamectin benzoate emerges as a promising candidate for inclusion in IPM programs. However, further research is necessary to determine its compatibility with other management strategies for controlling N. tenuis and other tomato pests.

Evaluating the efficiency and effectiveness of non-Newtonian fluid flow in a double-pipe heat exchanger with porous medium via numerical simulation

In the present work, the convection heat transfer and pressure drop of the turbulent flow based on a non-Newtonian fluid were numerically investigated in a double-pipe heat exchanger with various porous rings by considering the inner tube under constant heat flux. The solution of 0.1% and 2% mass carboxy methyl cellulose in deionized (DI) water water was used as the base non-Newtonian fluid. The fluid flow and heat transfer in this study were modeled by using the RNG K-ε turbulent viscosity with the enhanced wall treatment. The non-Newtonian power-law method was used in ANSYS Fluent software to resolve the flow within the numerical solution domain in the double pipe. Furthermore, the thermal performance of the heat exchanger, and the effects of the geometry, number, thickness, and height of the porous rings at the various Reynolds numbers were studied. According to the results, using non-Newtonian fluid had a significant effect on the average Nusselt number and pressure drop which were increased by up to 40.1% and 10 times, respectively. The annular tube possessing six porous rings at Re = 4,000 and height = 2 mm, thickness = 6 mm, applying non-Newtonian fluid can improve the efficiency of the system by up to 11.25%. It also found that by increasing the porous thickness, the Nusselt number increased by up to 56.3% at its maximum. The results have demonstrated a satisfactory level of agreement with experimental and correlation data by comparing them with existing data in similar literature.

Age, growth and mortality characteristics of the Thumbprint Emperor (Lethrinus harak) in Zanzibar

The growth parameters of Lethrinus harak were studied in Zanzibar water from 308 samples collected between June 2019 to May 2020 at Unguja Ukuu and Mkokotoni landing sites. The annulus count indicated that the majority of fishes captured were of three and four years old and very few were five, six, and seven years of age with a mean length of 17.69 cm, 21.04 cm, 24.18 cm, 25.86 cm, and 28.15, respectively. The number of rings was counted on the whole otolith and the growth rings were revealed to be formed annually, with the opaque margins generated from December to February and the hyaline ones during the rest of the year. The growth parameters were estimated as L∞=34.22cm, K=0.25 year-1, and t0=0.00. The total mortality (Z) was estimated as 0.68 year-1 and natural mortality (M) was estimated using Pauly's equation, as 0.65 per year-1 and fishing mortality (F) was 0.03 year-1, which gives an exploitation rate (E) of 0.04 year-1. Although these values indicate the species to be underexploited, the absence of older individuals 15 years and smaller below three years might have affected our findings.

Porphyromonas gingivalis outer membrane vesicles activate Toll-like receptor 2 to promote osteoclast differentiation by carrying lipopolysaccharide

Objective: To investigate the effects of Porphyromonas gingivalis derived outer membrane vesicles (Pg OMV) on osteoclast differentiation of macrophages and its underlying mechanisms. Methods: The morphology and the size distribution of Pg OMV were analyzed by transmission electron microscopy and nanoparticle tracing analysis, respectively. The osteoclast precursors were treated with 1, 3 and 10 mg/L Pg OMV (1, 3 and 10 mg/L OMV treatment group) or phosphate buffer solution (PBS)(control group). The formation of osteoclasts was analyzed by tartrate-resistant acid phosphase (TRAP) staining and F-actin staining and real-time quantitative PCR (RT-qPCR) were used to detect the expression of Fos and matrix metallopeptidase 9 (MMP9). Polymyxin B (PMB) was used to block lipopolysaccharide (LPS) and then Pg OMV was used to treat osteoclast precursor (PMB-OMV treatment group), and OMV treatment group was used as control. TRAP and F-actin staining were used to observe the formation of osteoclasts and actin rings. The effect of Pg OMV on the expression of Toll-like receptor (TLR) 2 and TLR4 in preosteoclasts was detected by Western blotting. The osteoclast precursors were pretreated with 10, 50, 100 and 200 μmol/L C29, an inhibitor of TLR2, and then treated with Pg OMV(OMV+10, 50, 100 and 200 μmol/L C29 treatment group) and OMV treatment group without C29 pretreatment was control. TRAP and F-actin staining were used to observe the formation of osteoclasts and actin rings. The osteoclast precursor cells were treated with OMV (OMV treatment group) and OMV incubated with PMB (PMB-OMV treatment group) and the expression of TLR2 in osteoclast precursor was detected by Western blotting. Results: Pg OMV showed classical vesicular structures, and the average particle size of Pg OMV were 179.2 nm. A large number of actin rings were observed in the 3 and 10 mg/L OMV treatment groups. The percentages of TRAP-positive osteoclast area in 3 mg/L OMV treatment group [(22.6±2.1)%] and 10 mg/L OMV treatment group [(32.0±2.3)%] were significantly increased compared with control group [(4.9±0.5)%] (P<0.001). Compared with the control group (1.000±0.029), the mRNA relative expression of Fos in 3 mg/L OMV treatment group (1.491±0.114) and 10 mg/L OMV treatment group (1.726±0.254) was significantly increased (P=0.013, P=0.001). Compared with the control group (1.007±0.148), the mRNA relative expression of MMP9 in the group of 10 mg/L OMV (2.232±0.097) was significantly increased (P<0.001). Actin ring formation was less in PMB-OMV treatment groups than in OMV treatment groups. The proportion of TRAP-positive osteoclasts area [(14.8±3.8)%] in PMB-OMV treatment group was significantly lower than OMV treatment group [(31.5±6.7) %] (P=0.004). The relative expression of TLR2 in OMV treatment group (1.359±0.134) was significantly higher than that in the control group (1.000±0.000) (t=4.62, P=0.044). Compared with the OMV treatment group [(29.4±1.7)%], 50, 100 and 200 μmol/L C29 significantly decreased the formation of osteoclasts [(24.0±1.7)%, (18.5±2.1)%, (9.1±1.3) %] (P=0.026, P<0.001, P<0.001). TLR2 protein expression in PMB-OMV group (0.780±0.046) was significantly lower than that in OMV group (1.000±0.000)(t=8.32, P=0.001). Conclusions: Pg OMV can promote osteoclast differentiation by carrying LPS, TLR2 plays an important role in Pg OMV mediated osteoclast differentiation.

A parametric study on the effect of ring damper on wheel damping

Ring dampers have been widely applied to control vibration of, and noise from, train wheels due to the simple structure, negligible impact on operational safety and potential in vibration and noise reduction. Yet, parameters affecting the vibro-acoustic performance of a ring-damped wheel are not adequately studied. In this paper, the apparent modal damping ratios of a ring-damped wheel are studied numerically using a finite element model allowing for frictional nonlinearity. Studied parameters include the impact force used to excite the wheel, the preload in the ring, the friction coefficient of the interface between the ring and the wheel, and the number of rings installed. Several findings can be drawn from the study. Installation of one or two rings to the wheel does not change the resonance frequencies (they are also termed the modal frequencies of the ring-damped wheel) but reduces the resonance responses by generating extra damping to the modes. The ring is more effective for radial excitation than for axial excitation. At most modal frequencies, damping with double rings is higher than with a single ring. Although there are few modal frequencies at which the modal damping ratios are reduced by installing the second ring, the average damping ratio with two rings is much higher, by a factor of 2.37 for axial excitation and 1.73 for radial excitation, than that with a single ring. The apparent damping of the ring-damped wheel increases with the level of the impact force, especially for radial excitation. There is an optimal combination of the preload in the ring and the frictional coefficient with which damping induced by the ring is the highest. Besides, the average damping ratios of the modes above 2000 Hz are proposed to be an indicator of the effectiveness of the performance of a ring-damped wheel in noise reduction.

Qualitative and quantitative anatomical characteristics and radial variation of major cell components in Paulownia tomentosa wood grown in Korea

Qualitative and quantitative anatomical characteristics and radial variations of the major cell components in Paulownia tomentosa wood were examined using optical microscopy and X-ray diffraction to aid in wood identification and as quality indices. The vessel arrangement on the transverse surface was either ring-porous or semi-ring-porous. Most vessels had solitary pores, while some vessels had multiple radial pores. The axial parenchyma was generally confluent and partially of aliform type. Tyloses with high frequency in the vessel lumen and multiseriate rays (2 to 5 cells) were typical. The vessel diameter of earlywood and latewood was approximately 240 and 107 μm, respectively, with a range of 165 to 289 μm in earlywood and 55 to 149 μm in latewood. Ray height and fiber length were approximately 178 and 740 μm, respectively. The vessel diameter in both earlywood and latewood and the fiber length increased gradually with an increasing number of growth rings. Ray height was constant from the pith to the middle section and decreased toward the bark. The anatomical characteristics and radial variation of major components of P. tomentosa can be used as wood identification keys and quality indices.

Poly(ester imide)s with Low Linear Coefficients of Thermal Expansion and Low Water Uptake (VII): A Strategy to Achieve Ultra-Low Dissipation Factors at 10 GHz.

In this study, a series of ester-linked tetracarboxylic dianhydrides (TCDAs) with 2,6-naphthalene-containing longitudinally extended structures consisting of different numbers of aromatic rings (NAr = 6-8) was synthesized to obtain novel modified polyimides, poly(ester imide)s (PEsIs). These TCDAs were fully compatible with the conventional manufacturing processes of conventional polyimide (PI) systems. As an example, the PEsI film obtained from the ester-linked TCDA (NAr = 8) and an ester-linked diamine achieved unprecedented outstanding dielectric properties without the support of fluorinated monomers, specifically an ultra-low dissipation factor (tan δ) of 0.00128 at a frequency of 10 GHz (50% RH and 23 °C), in addition to an extremely high glass transition temperature (Tg) of 365 °C, extremely low linear coefficient of thermal expansion (CTE) of 6.8 ppm K-1, suppressed water uptake (0.24%), requisite film ductility, and a low haze. Consequently, certain PEsI films developed in this study are promising candidates for heat-resistant dielectric substrates for use in 5G-compatible high-speed flexible printed circuit boards (FPCs). The chemical and physical factors denominating tan δ are also discussed.

The Conductance Isotope Effect in Oligophenylene Imine Molecular Wires Depends on the Number and Spacing of 13C-Labeled Phenylene Rings.

We report a strong and structurally sensitive 13C intramolecular conductance isotope effect (CIE) for oligophenyleneimine (OPI) molecular wires connected to Au electrodes. Wires were built from Au surfaces beginning with the formation of 4-aminothiophenol self-assembled monolayers (SAMs) followed by subsequent condensation reactions with 13C-labeled terephthalaldehyde and phenylenediamine; in these monomers the phenylene rings were either completely 13C-labeled or the naturally abundant 12C isotopologues. Alternatively, perdeuterated versions of terephthalaldehyde and phenylenediamine were employed to make 2H(D)-labeled OPI wires. For 13C-isotopologues of short OPI wires (<4 nm) in length where the charge transport mechanism is tunneling, there was no measurable effect, i.e., 13C CIE ≈ 1, where CIE is defined as the ratio of labeled and unlabeled wire resistances, i.e., CIE = Rheavy/Rlight. However, for long OPI wires >4 nm, in which the transport mechanism is polaron hopping, a strong 13C CIE = 4-5 was observed. A much weaker inverse CIE < 1 was evident for the longest D-labeled wires. Importantly, the magnitude of the 13C CIE was sensitive to the number and spacing of 13C-labeled rings, i.e., the CIE was structurally sensitive. The structural sensitivity is intriguing because it may be employed to understand polaron hopping mechanisms and charge localization/delocalization in molecular wires. A preliminary theoretical analysis explored several possible explanations for the CIE, but so far a fully satisfactory explanation has not been identified. Nevertheless, the latest results unambiguously demonstrate structural sensitivity of the heavy atom CIE, offering directions for further utilization of this interesting effect.

Examining diverse remediation mechanisms of biochar in soil contaminated with polycyclic aromatic hydrocarbon (PAH) of various ring structures: A global meta-analysis

Biochar is a widely recognized solution for addressing polycyclic aromatic hydrocarbon (PAH) contamination. However, it is unclear how the different physicochemical properties of PAHs affect remediation mechanisms, thereby affecting the remediation efficiency of biochar. In this study, a meta-analysis of 56 studies with 2236 observations was conducted to quantify the contributions of the preparation parameters and physicochemical properties of biochar, soil properties, and application measures to remediation efficiency. The research results revealed that PAH contents in the contaminated soil were significantly reduced by an average of 24.99 % after the application of biochar. Random Forest analysis identified feedstock, biochar SSA, soil pH, and rate of biochar application to be the most critical factors among the four categories. The reduction of PAH contents in the contaminated soil first decreased from 37.61 % to 17.44 % and then increased to 40.29 % with an increase in the number of aromatic rings from 2 to 6. Our study results suggest that biochar prepared from bio-waste at low temperatures could be favorable for reducing the content of NAP in soil. Wood-derived biochar pyrolyzed at a relatively high temperature is recommended for remediation of soil contaminated with PAHs with 5 or 6 aromatic rings. Our study provides a new perspective and an optimized strategy for the remediation of PAH-contaminated soils with biochar.

Atom-bond-connectivity (ABC) indices of graphene sheets, zigzag single walled carbon nanotubes and single walled carbon nanotori

Abstract Atom-bond-connectivity (ABC) indices are obtained in analytical forms for graphene sheets, zigzag single walled carbon nanotubes (SWCNTs), and single walled carbon nanotori in terms of number of rings (r) that measures the length and the number of hexagons in between two rings (h) that dictates the width of the concerned systems. The procedures followed for ABC index have been used to obtain the expressions of augmented Zagreb and Randić indices for such systems. Logarithm of ABC indices of zigzag SWCNTs are found to correlate linearly well with the bond dissociation energies per C–C bond and the Young’s moduli of said SWCNTs with fixed number of rings (r) but varying number of hexagons (h) in between two successive rings. The plot of logarithm of ABC index versus Young’s modulus of such SWCNTs in varying both r and h simultaneously is not a straight line but fits well with the sigmoidal (Boltzmann) curve. Wiener index, one of the important distance based index, has recently been found to have similar correlations with the concerned properties of such systems. Similar plots would appear for the said properties of the zigzag SWCNTs with other degree-based indices like augmented Zagreb and Randić indices, as have been indicated from their respective expressions obtained.

Nitrogen-reliant degradation behaviors of characteristic NHCs by UV-based advanced oxidation processes: Kinetics, pathways and toxicity assessment

In recent decades, nitrogen-containing heterocyclic compounds (NHCs) have been widely synthesized and applied due to their excellent coordination capability of heterocyclic N atoms. However, their high toxicity and poor biodegradability pose significant hazards to aquatic ecosystems. Three characteristic NHCs (cNHCs) with similar molecular structures but minor differences in the number and position of N atoms, namely benzotriazole (BTA), benzimidazole (BMZ), and indazole (IDZ), were selected to evaluate impacts of these differences on their degradation behaviors during UV/H2O2 treatments. It was found that the key mechanism for the removal of BTA, BMZ, and IDZ in the UV/H2O2 processes was the generation of ∙OH through UV-excited H2O2 decomposition. Density functional theory (DFT) calculations revealed that the variation in the number and position of heterocyclic ring N atoms significantly affected the electron cloud distribution of the cNHCs, thereby resulting in different reactivities. Mineralization results and N evolution experiments indicated that N elements were initially released in the form of ammonia nitrogen during UV/H2O2 treatments, which then underwent oxidation to form nitrite and nitrate. The two ortho-N atoms were most easily mineralized and release inorganic nitrogen, followed by the two meta-N atoms. However, the BTA compound containing three N atoms, exhibited inertness towards radicals after hydroxylation, thereby hindering mineralization. A dual-directional transformation products (TPs) identification protocol was employed to identify 30 TPs of the cNHCs and propose recommended degradation pathways. Furthermore, Vibrio fischeri bioluminescence inhibition bioassay and QSAR prediction models were used to preliminarily screen and identify 13 toxic TPs with potential ecological risks.

Periodic transmission theory of circularly symmetric multi-ring solitons in nonlinear Schrödinger equation

In this paper, the evolution characteristics of periodic transmission of circularly symmetric multi-ring solitons in optical nonlocal materials based on nonlinear Schrödinger equation are investigated in detail. The transmission expression of circularly symmetric multi-ring solitons has been derived. It was found that the number and size of rings in these solitons can be controlled by initial parameters. The transmission of circularly symmetric multi-ring solitons is similar to that of high-order temporal solitons in nonlinear fibers, exhibiting periodic variations. When the input energy is a specific value, the statistical width of circularly symmetric multi-ring solitons remains constant during transmission, otherwise it exhibits periodic changes, which can be considered as generalized breathing solitons. The influence of various parameters on the transmission characteristics has been analyzed in detail, and some important transmission characteristics have been intuitively demonstrated through numerical simulation.

Numerical Study of the Buckling Response of Stiffened FG Graphene-Reinforced Multilayer Composite Cylindrical Panels

The present research aims at determining the axial buckling load of stiffened multilayer cylindrical shell panels made of functionally graded graphene-reinforced composites (FG-GPL RCs). Rings and stringers are applied as stiffening tools for shell panels, whose elastic properties are determined according to the Halpin–Tsai relations. The virtual work principle and finite element approach are implemented here, according to a first-order shear deformation theory (FSDT) and Lekhnitskii smeared stiffener approach, in order to determine the governing equations of the stability problem. Four different dispersions of nanofillers are assumed in the thickness direction, including the FG-X, FG-A, FG-O, and UD distributions. A large systematic investigation considers the effect of different geometric and material parameters on the buckling loads and mode shapes of the stiffened FG-GPL RC cylindrical shell panel, primarily the dispersion and weight fractions of the nanofiller, the number of rings and stringers, and the boundary conditions, with useful insights for design purposes.

Associations of Upper-Extremity Exercise Capacity and Grip Strength With Cognitive Domains in Patients With COPD.

Cognitive impairment (CI), which has been reported in COPD, has been related to physical performance. However, the association between CI and upper-extremity functions is unknown. We aimed to compare upper-extremity exercise capacity and grip strength between subjects with COPD with and without CI and to determine the relationship of upper-extremity functions with specific cognitive domains. In this cross-sectional study, 76 subjects with COPD (mean age 66.8 ± 7.5 y, FEV1% 47.12 ± 14.10) were classified as with and without CI according to the Montreal Cognitive Assessment. Clinical characteristics, upper-extremity exercise capacity (6-min pegboard ring test [6PBRT]), grip strength (hand dynamometer), dyspnea severity (modified Medical Research Council dyspnea scale), disease-specific health status (COPD Assessment Test), and disease-specific quality of life (St George Respiratory Questionnaire) were compared between groups, and the relationship of upper-extremity functions with cognitive subdomains was analyzed by multivariate regression analysis. The number of 6PBRT rings (P = .01) and the grip strength (P = .033) were lower in subjects with CI. Subjects with CI had lower FEV1% (P = .038), arterial oxygenation (P = .002), exercise habits (P = .033), health status (P = .01), quality of life (P = .042); and higher dyspnea (P < .001), smoking consumption (P = .032), emergency admission (P = .02), and hospitalization (P = .042). The adjusted model showed that executive functions and attention were related to upper-extremity capacity (β = 14.4 and β = 10.2, respectively) and hand-grip strength (β = 1.85 and β = 1.49, respectively). These findings suggest that upper-extremity functions might be decreased especially concerning executive functions and attention in subjects with COPD with CI.

Assessment of Bioavailability Parameters of Mono- and Bistriazole Derivatives of Propynoylbetulin

Bioavailability describes the properties that determine the passage of a compound through biological barriers. In many cases, bioavailability depends on the lipophilicity of the compound. In this study, the lipophilicity as well as other bioavailability properties of the mono- and bistriazole derivatives of betulin are presented. The lipophilicity was determined using RP-TLC and theoretical methods. The experimental lipophilicity of mono- and bistriazole derivatives is in the range from 4.39 to 7.85 and from 3.75 to 8.83, respectively. The lipophilicity of mono- and bistriazoles is similar, and the logPTLC depends on the type of substituent at the triazole ring. The introduction of a substituent with oxygen and nitrogen atoms decreases lipophilicity. Comparing the experimental and theoretical lipophilicity shows that the milogP and XLOGP3 programs best reproduce the experimental values. The in silico-determined pharmacokinetic parameters show that monotriazole derivatives could be used as oral drugs while bistriazoles show low availability after oral administration. Triazoles could be used as transdermal drugs. The analysis of in silico bioavailability parameters shows that the type of substituent at the triazole ring influences the pharmacokinetic properties, while the number of triazole rings slightly affects the bioavailability properties of the compound.

Design and experimental verification of phase-reversal Fresnel lens for contact stress characterization

The accurate characterization of the contact stress on the mating surfaces of assembly components is a key means to ensure the assembly accuracy and operational safety of aero-engines. In this paper, a phase-reversal Fresnel lens for contact stress characterization is designed to solve the problem of low spatial resolution of contact stress characterization by the non water immersion ultrasonic method. The phase-reversal Fresnel lens is used to focus the ultrasonic wave on the mating surface of the assembly components to improve the spatial resolution of the contact stress characterization. The finite element simulation method is used to analyze the influence of the number of lens rings, the piezoelectric plate's diameter, the lens's thickness, and the groove depth on the focusing characteristics of Fresnel lenses. The power spectrum peak is used to analyze the residual reflected wave energy of the mating surface. According to the correlation between the residual reflected wave energy and the contact stress, a correlation model between the two is built to realize the characterization of the contact stress. This study provides a promising method for the characterization of contact stress on the mating surface of aero-engine assembly components by non water immersion focused ultrasound.