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Background: Primary syphilis is characterized by painless ulcerative lesions in the genitalia, the aetiology of painless remains elusive. Objectives: To investigate the role of Treponema pallidum in painless ulcer of primary syphilis, and the mechanisms underlying painless ulcers caused by T. pallidum. Methods: An experimental rabbit model of primary syphilis was established to investigate its effects on peripheral nerve tissues. Human skin fibroblasts were used to examine the role of T. pallidum in modulating neurotransmitters associated with pain and to explore the signalling pathways related to neurotransmitter secretion by T. pallidum in vitro. Results: Treponema pallidum infection did not directly lead to neuronal damage or interfere with the neuronal resting potential. Instead, it facilitated the secretion of prostaglandin E2 (PGE2) through endoplasmic reticulum stress in both rabbit and human skin fibroblasts, and upregulation of PGE2 induced the hyperpolarization of neurones. Moreover, the IRE1α/COX‐2 signalling pathway was identified as the underlying mechanism by which T. pallidum induced the production of PGE2 in human skin fibroblasts. Conclusion: Treponema pallidum promotes PGE2 secretion in skin fibroblasts, leading to the excitation of neuronal hyperpolarization and potentially contributing to the pathogenesis of painless ulcers in syphilis. [ABSTRACT FROM AUTHOR]

Halitosis is a common oral condition, which leads to social embarrassment and affects quality of life. Cumulative evidence has suggested the association of tongue-coating microbiome with the development of intraoral halitosis. The dynamic variations of tongue-coating microbiota and metabolites in halitosis have not been fully elucidated. Therefore, the present study aimed to determine the tongue-coating microbial and metabolic characteristics in halitosis subjects without other oral diseases using metagenomics and metabolomics analysis. The participants underwent oral examination, halitosis assessment, and tongue-coating sample collection for the microbiome and metabolome analysis. It was found that the microbiota richness and diversity were significantly elevated in the halitosis group. Furthermore, species from Actinomyces, Prevotella, Veillonella, and Solobacterium were significantly more abundant in the halitosis group. However, the Rothia and Streptococcus species exhibited opposite tendencies. Eleven Kyoto Encyclopedia of Genes and Genomes pathways were significantly enriched in the halitosis tongue coatings, including cysteine and methionine metabolism. Functional genes related to sulfur, indole, skatole, and cadaverine metabolic processes (such as serA, metH, metK and dsrAB) were identified to be more abundant in the halitosis samples. The metabolome analysis revealed that indole-3-acetic, ornithine, and L-tryptophan were significantly elevated in the halitosis samples. Furthermore, it was observed that the values of volatile sulfur compounds and indole-3-acetic abundances were positively correlated. The multiomics analysis identified the metagenomic and metabolomic characteristics to differentiate halitosis from healthy individuals using the least absolute shrinkage and selection operator logistic regression and random forest classifier. A total of 19 species and 39 metabolites were identified as features in halitosis patients, which included indole-3-acetic acid, Bacillus altitudinis, Candidatus Saccharibacteria, and Actinomyces species. In conclusion, an evident shift in microbiome and metabolome characteristics was observed in the halitosis tongue coating, which may have a potential etiological significance and provide novel insights into the mechanism for halitosis. [ABSTRACT FROM AUTHOR]

We report the phase-resolved spectral results of the first Galactic pulsating ultraluminous X-ray source (PULX) Swift J0243.6+6124, modeling its 2017–2018 outburst peak using data collected by the Hard X-ray Modulation Telescope (Insight-HXMT). The broad energy coverage of Insight-HXMT allows us to obtain a more accurate spectral continuum to reduce the coupling of broad iron line profiles with other components. We use three different continuum spectrum models but obtain similar iron line results. For the first time, we detect the pulse characteristics of the broad iron line in a PULX. The variation in the width and intensity of this iron line with σ ∼ 1.2–1.5 keV has a phase offset of about 0.25 from the pulse phase. We suggest that the uneven irradiation of the thick inner disk by the accretion column produces the modulated variation of the broad iron line. In addition, the nonpulsed narrow line is suggested to come from the outer disk region. [ABSTRACT FROM AUTHOR]

We present a comprehensive timing analysis on the Be/X-ray binary pulsar RX J0440.9+4431 using observations from NICER and Insight - HXMT during the 2022–2023 outburst. The power density spectrum (PDS) of RX J0440.9+4431 exhibits typical aperiodic variability in X-ray flux across a wide frequency range. During a supercritical accretion state, we detect quasi-periodic oscillations (QPOs) at 0.2–0.5 Hz in the light curves of five pulses for RX J0440.9+4431. The observed QPOs manifest during flares, while the flares appear at the peaks of the pulse profiles on a time-scale of seconds and are primarily caused by an increase in hard photons. These flares can be explained by increased material ingestion in the accretion column at a fixed phase, primarily generating hard photons. Alternatively, an increase in accretion rate, independent of phase, may result in highly beamed hard photons within the accretion column, causing the flares. We argue the origin of QPOs to instabilities within the accretion flow. Additionally, we find that the break frequencies in the noise power spectra align well with |$\propto L_{\mathrm{x}}^{3 / 7}$| across three orders of magnitude in the luminosity, which points to a relatively strong magnetic field in RX J0440.9+4431, estimated to be ~1013 G. [ABSTRACT FROM AUTHOR]

The micrometer-scale internal defect in the capsule is one of the most important factors that limit implosion performance in inertial confinement fusion (ICF) experiments, which creates instability seeds as shocks propagate through the capsule shell. Here, we report the generation mechanism of vortex pairs resulting from the interaction of shock waves with multiple bubbles, as well as the origin of more intricate perturbation waves than those observed in the case of single defects. Based on the subsequent evolution of hydrodynamic instability, it is evident that the vortex pairs induce the emergence of low-density (light-bubble case) or high-density (referred to as heavy-bubble case) jets on the ablative front. The presence of multiple side-by-side defects can rapidly amplify the dimensions of the jet. These jets could be responsible for the "meteor shower" observed in implosion experiments. Converging disturbed waves between vertically aligned defects lead to a more complex nonlinear flow field evolution compared to the scenario with a single defect. A systematic study of localized perturbation growth as a function of defect placement is presented. We investigate the dependence of circulation in the flow field on the locations of the defects. The scanning results of defect scenes with different sizes revealed the reason why the depth of fluid penetration is affected by the position and size, and found that the effects of the position and size on the perturbation expansion width can be equivalent to a certain extent. The extension of the perturbation width when the defect is off-axis limits the degree of penetration of the perturbation depth. The results contribute to a more comprehensive understanding of physical processes, such as the seeding mechanism, shell integrity, and mass injection into the central region, which may be applied to inform the development of more effective strategies to mitigate implosion degradation in ICF implosion experiments. [ABSTRACT FROM AUTHOR]

The instantaneous strong load generated by an explosion outside of a subway tunnel can destabilize and damage the tunnel's lining, and thus endanger human safety and property. To avoid this risk, it is necessary to investigate the dynamic response and damage of subway tunnels under explosion-induced loads. This study used the ANSYS/LS-DYNA software to establish the finite element model of a tunnel. The surface side blast angle, tunnel buried depth, and explosive equivalent were the considered variables, and the dynamic response and damage of the tunnel's lining structure under an external blast-related load were analyzed. The results reveal that, when the side blasting angle was 15°, the tensile strain was 150 on the left side, which means that the horizontal deformation of the lining cannot be ignored. When the buried depth of the tunnel was used as the main variable, the damping effect of the soil medium was obtained by comparing the displacement–time and velocity–time data. This comparison provides a reference for reasonably setting the tunnel depth in similar projects. When the explosive equivalent was considered as the main variable, the overall instability caused by the local damage of the lining structure was analyzed. The findings of this study can be used to improve the design of effective countermeasures and systems for protecting tunnels from external explosions, and have high technical, economic, and social importance and reference value for similar engineering design projects. [ABSTRACT FROM AUTHOR]

RX J0440.9+4431, a Be/X-ray binary, had its brightest outburst in 2022 since its discovery, with a peak X-ray flux of 2.25 Crab (as recorded by Swift /BAT, 15–50 keV). We analyze the timing properties of this giant outburst using data from Insight -Hard X-ray Modulation Telescope and Neutron Star Interior Composition Exlporer , focusing on the evolution of the pulse profile and pulse fraction. We observe that when the luminosity reached around ~ |$3\times 10^{37}\ {\rm erg\ \rm s^{-1}}$|⁠ , a transition from double-peaked to single-peaked pulse profiles occurred across the energy range, with the peak of the low-energy profile aligning gradually with the peak of the high-energy profile. This change indicates a transition from subcritical to supercritical accretion. Additionally, we found a concave in the pulse fraction as a function of energy around 20–30 keV throughout the entire outburst period. Compared to the low luminosity, the concave becomes weaker in high luminosities, and overall, the pulse fraction is higher. We propose that this concave could be caused by the scattering of high-energy photons by the atmosphere of a neutron star, leading to a dilution of the pulse fraction. As the accretion reaches the supercritical state, the accretion column height increases, resulting in a larger direct component of strongly beamed X-ray flux, and an elevated pulse fraction. [ABSTRACT FROM AUTHOR]

MAXI J1816–195 is a newly discovered accreting millisecond X-ray pulsar that went outburst in 2022 June. Through timing analysis with Neutron star Interior Composition Explorer (NICER) and Nuclear Spectroscopic Telescope Array (NuSTAR) observations, we find a transient modulation at ~2.5 Hz during the decay period of MAXI J1816–195. The modulation is strongly correlated with a spectral hardening, and its fractional rms amplitude increases with energy. These results suggest that the modulation is likely to be produced in an unstable corona. In addition, the presence of the modulation during thermonuclear bursts indicates that it may originate from a disc-corona where the optical depth is likely the main factor affecting the modulation, rather than temperature. Moreover, we find significant reflection features in the spectra observed simultaneously by NICER and NuSTAR , including a relativistically broadened Fe-K line around 6–7 keV, and a Compton hump in the 10–30 keV energy band. The radius of the inner disc is constrained to be R in  = (1.04–1.23)  R ISCO based on reflection modeling of the broad-band spectra. Assuming that the inner disc is truncated at the magnetosphere radius, we estimate that the magnetic field strength is |$\le 4.67 \times 10^{8}\, \rm G$|⁠. [ABSTRACT FROM AUTHOR]

During the construction and operation of a geological repository, with the infiltration of groundwater, highly compacted bentonite blocks hydrate and swell freely to fill up technological voids and gradually turn to hydrate under a constant-volume condition. Additionally, these processes are inevitably influenced by the pore chemistry of the groundwater. Therefore, it is necessary to investigate the hydration process of compacted bentonite under the combined influences of chemistry and technological voids. In this study, hydration tests were conducted on compacted GMZ bentonite with artificial annular gaps with infiltration of deionized water, 1 M NaCl, and 1 M CaCl2 solutions, respectively. Variation of swelling pressure and hydraulic conductivity with time was measured during hydration. The distribution of dry density, water content, and microstructure feature in the specimens was determined. Results show that sealing of the technological voids resulted in a heterogeneous distribution of dry density and water content of the barrier formed. Compared to that of deionized water, infiltration of salt solutions weakened swelling capacity and increased the permeability, leading to more significant heterogeneity in dry density distribution. During hydration, the specimen could be divided into swelling and compression zones according to variations of dry density with time. The boundary between the swelling and compression zones moved with hydration time. Evolutions of microstructure features were also affected by solutions. For specimens infiltrated with NaCl, more macro-pores and meso-pores were observed, while for CaCl2 infiltration, more undetectable pores and less meso-pore pores could be detected. After the tests, all the specimens were still in non-homogeneous states. [ABSTRACT FROM AUTHOR]

We investigate herein how long-wavelength perturbations affect the nonlinear evolution of the multimode ablative Rayleigh–Taylor instability (ARTI). A single-mode ARTI with an initial small amplitude is first investigated to validate the reliability of the proposed simulation code. The results show that both linear growth rates and asymptotic bubble velocities obtained from simulations are in reasonable agreement with theoretical results. Initial perturbations with different long-wavelength perturbations are compared to investigate the contribution of the long-wavelength perturbations to the nonlinear evolution of the ARTI mixing. Beyond the nonlinear saturation limit [S. W. Haan, Phys. Rev. A 39, 5812 (1989)], the long-wavelength perturbation promotes the ARTI mixing and facilitates the development of the large-scale structure on the ablation surface. In the self-similar analysis, the simulation results indicate that the self-similar growth parameters decrease with increasing initial longest-wavelength modes. [ABSTRACT FROM AUTHOR]

Imidazo[1,2-b]pyridazine derivatives have good biological activity and have been widely studied in drug molecules. In this study, a new compound, ethyl 6-chloro-3-fluoroimidazo[1,2-b]pyridazine-2-carboxylate, was synthesized. The title compound was characterized by spectroscopic techniques. Its single crystal was confirmed using X-ray diffraction (XRD). The optimized molecular crystal structures were determined on the basis of density functional theory (DFT) calculations using B3LYP/6-311+G(2d,p) functional. Compared with X-ray diffraction data, the results were consistent. Molecular electrostatic potential (MEP) and frontier molecular orbital (FMOs) analyses of the title compound were preformed using computational methods. Infrared vibrational analysis of the target compound was also conducted. [ABSTRACT FROM AUTHOR]

It is believed that isolated defects within the capsule (e.g., void, high-density inclusion) can be one of the essential factors for implosion performance degradation by seeding hydrodynamic instabilities in implosions. Nonetheless, a systematic study on how the isolated defects evolve and why they are not stabilized by ablation given the length scale comparable with the typical cutoff wavelength is still lacking. This paper addresses the above concerns by looking into a simplified model where a planar shell (without convergent geometry) is driven by laser direct-drive, with a single defect (low/high density) of micrometer or sub-micrometer scale residing at different locations inside. The underlying dynamics of two key physical processes are analyzed, i.e., the shock–bubble interactions as well as the subsequent nonlinear evolution of ablative hydrodynamic instabilities initiated by the direct interaction of the deformed defect and ablation front, revealing that compressibility and baroclinic effects drive vorticity production during the interactions between the shock wave and the isolated defect. In the "light-bubble" case, the vortex pair generated in the first process is further strengthened by the laser ablation. Hence, a directed flow is formed in companion with the persistent flow entering the bubble of the surrounding ablator. The bubble exhibits a remarkable growth both laterally and deeply, seriously threatening the shell's integrity. The positive feedback mechanism of the vortex pair is absent in the "heavy-bubble" counterpart, and the ablation stabilization manifested itself in the reduction of spike amplitude. A systematic study of localized perturbation growth as a function of defect placement, size, and preheating intensity is presented. [ABSTRACT FROM AUTHOR]

During the shield-based construction of a large-diameter subway tunnel crossing sandy cobble strata in the Chengdu region, a number of problems are encountered: the large particle size, high strength, loose structure of cobbles and boulders, difficulty in discharging slag and soil from the shield, and serious wear of the cutter head. It is necessary to adopt a dynamic control method to reduce material consumption using multiple groups of residue improvement experiments. Unlike other methods, we propose two improvement schemes and a dynamic control process in this paper. A dynamic control scheme combined with shield parameter feedback is proposed, using different proportions of modifiers to improve the sandy cobble strata. [ABSTRACT FROM AUTHOR]

The secondary impact of automotive transmission and its adverse effect on the shift process has attracted widespread attention in the automotive industry. Based on comparing the defects of the asymmetric tooth structure widely used at present and expounding its application limitations, this paper puts forward a novel high-low tooth synchronizer with the characteristics of simple structure, easy to realize large-scale production, and not limited by the use position, in order to achieve the improvement purpose of reducing the secondary impact. And then, GSA test equipment is applied to test the feasibility of using the high-low tooth structure in the second gear in the synchronizer of a 6-gear manual transmission to reduce the secondary impact. The research results clearly indicated that the high-low tooth structure of vehicle synchronizer could effectively improve the secondary impact in the shift process of vehicle transmission, which provides a new research path for domestic and foreign transmission manufacturers to solve the secondary impact. [ABSTRACT FROM AUTHOR]

The influence of thin-shell effects on the nonlinear evolution of two-dimensional single-mode ablative Rayleigh–Taylor instability (ARTI) is studied in the parameter range of inertial confinement fusion implosions. A new phase of unsaturated nonlinear bubble evolution caused by thin-shell effects is found. This is different from the traditional opinion that the bubble velocity becomes saturated after the ARTI evolution enters a highly nonlinear regime. A modified bubble velocity formula is proposed, based on the Betti–Sanz model [Betti and Sanz, Phys. Rev. Lett. 97, 205002 (2006)], considering the thin-shell effects. It is shown that the bubble velocity becomes saturated in the thick-target case after the ARTI evolution enters a highly nonlinear regime. In this case, the Betti–Sanz bubble dynamics model can predict the evolution of bubble velocity. However, when the thin-shell effects become significant in the case of k D 0 < 100, where D 0 is the initial thickness of the target and k is the perturbation wavenumber, the difference of the average acceleration between the bubble vertex and the spike tip can be much more significant than that of the thick-target case. In this situation, the nonlinear evolution of the ARTI bubbles will accelerate without saturation until the target breakup, which cannot be depicted by the Betti–Sanz model while the improved theory formula is applicative. The Betti–Sanz model and the improved theory formula are independent of the initial perturbation amplitude. [ABSTRACT FROM AUTHOR]

The development of nasopharyngeal carcinoma (NPC) and its unique geographic distribution have long been attributed to a combination of dietary intake of salt-preserved fish, inherited susceptibility, and early-life infection with the Epstein-Barr virus (EBV). New findings from our large, rigorously designed, population-based case–control study of NPC in southern China have enabled substantial revision of this causal model. Here, we briefly summarize these results and provide an updated model of the etiology of NPC. Our new research identifies two EBV genetic variants that may be causally involved in the majority of NPC in southern China, and suggests the rise of modern environmental co-factors accompanying cultural and economic transformation in NPC-endemic regions. These discoveries can be translated directly into clinical and public health advances, including improvement of indoor air quality and oral health, development of an EBV vaccine, enhanced screening strategies, and improved risk prediction. Greater understanding of the roles of environmental, genetic, and viral risk factors can reveal the extent to which these agents act independently or jointly on NPC development. The history of NPC research demonstrates how epidemiology can shed light on the interplay of genes, environment, and infections in carcinogenesis, and how this knowledge can be harnessed for cancer prevention and control. [ABSTRACT FROM AUTHOR]

A weakly nonlinear (WN) theoretical model for the two-dimensional incompressible Kelvin–Helmholtz instability (KHI) is proposed. Its solution form is the complete expansion in real space. The transition from linear to nonlinear growth is analytically studied via third-order solutions of plane KHI initiated by a single-mode surface perturbation. The difference between the WN growth of the Rayleigh–Taylor instability (RTI) in plane geometry and the WN growth of the KHI in plane geometry is discussed. It is found that there are resonance solutions in the higher harmonics of KHI but not in RTI. The vertex of spikes and bubbles is deflected because of the shearing effect in KHI compared with that in RTI. The spike velocity increases with the Atwood number before a particular time and then inversely after that time. There is no such reversal in RTI. However, the bubble velocity with the Atwood number of KHI has the same evolution rule as that of RTI. In addition to the influence of initial perturbation on the nonlinear saturation amplitude, the influence of Atwood number on the nonlinear saturation amplitude of the fundamental mode is obtained. Finally, compared with the numerical simulations, at the same initial conditions, the analytical solutions up to the third harmonics are well consistent with the simulated datum in the linear and weakly nonlinear stages for a widely varied Atwood number. [ABSTRACT FROM AUTHOR]

The estimation of snow hazard and load faces the small sample size effect because of the short snow depth record at a station. To reduce such an effect, we propose to estimate the return period value of the annual maximum ground snow depth S, sT, for Canada sites by applying the regional frequency analysis (RFA) and the region of influence approach (ROIA). The use of RFA and ROIA to map Canadian snow hazard is new. The comparison of their performance for snow hazard mapping has not been explored in the literature. We also consider the at-site analysis approach (ASA) for estimating sT by using three often used probability distributions for S. A comparison of the estimated sT by using the three approaches (ASA, RFA, ROIA) indicates that there is considerable scatter between the estimated sT value although the identified overall spatial trends of sT are similar. It is shown that the two-parameter lognormal distribution for S at most Canadian sites, based on the at-site analysis, is preferred; this differs from the Gumbel distribution used to develop the design snow load in Canadian structural design code. The new findings indicate that it is valuable to consider the lognormal distribution for developing design snow load for Canadian sites. [ABSTRACT FROM AUTHOR]

During the long-term operation of a repository, bentonite–sand mixture could invade into fractures in the surrounding rock with infiltration of groundwater, resulting in loss of bentonite from the barrier with possible leakage of nuclides and consequently endangers the safety of the repository. In this work, an apparatus was designed with an artificial joint (fracture) being made between two parallel stacked transparent acrylic plates with a stainless-steel gasket inserted. Intrusion tests were conducted on the mixture specimens with different sand contents into artificial fractures with two sizes. A flow with constant velocity was applied to simulate seepage in the surrounding rock formations. Images were regularly captured with a camera, and parameters including the intrusion distance and widths of the non-accessory and accessory mineral rings were determined using a commercial software. Simultaneously, fluid was collected at the outlet and the erosion rate bentonite was determined by a turbidimeter. Finally, based on the force equilibrium, an intrusion model for describing bentonite–sand mixture intrusion into fractures with consideration of sand content and seepage effects was established and verified. Results show that the intrusion distance, two-region widths, and erosion mass decrease significantly with increasing sand content. After intrusion, the dry density of the bentonite specimen nearby the extrusion port decreases with increasing sand content and fracture size. Meanwhile, results of XRD tests indicate that the ratio of accessory minerals in the accessory mineral ring was higher than that in the pure Gaomiaozi bentonite specimen. Verifications confirmed that the intrusion model proposed in this work can well simulate the data measured. [ABSTRACT FROM AUTHOR]

In this work, methyl(tert-butoxycarbonyl)-L-tyrosinate and methyl(2,2,2-trifluoroacetyl)-L-tyrosinate are synthesized, and their structures are confirmed spectroscopically. Single crystals of these compounds are studied by X-ray diffraction. The optimized molecular structure is determined by density functional theory (DFT) calculations using the B3LYP/6-311G(2d,p) basis set, and the structure is compared with the X-ray structure. Conformational analyses reveal that the experimentally obtained and theoretically predicted structures are consistent with each other. In addition, molecular electrostatic potentials and frontier molecular orbitals of the two compounds are studied by DFT to reveal certain physicochemical properties of the compounds. [ABSTRACT FROM AUTHOR]

N-(2-fluoro-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)-3-methyl-butanamide is an important boric acid derivative. In this article, the title compound is obtained by a two-step substitution reaction. The structure of the title compound is verified by FTIR, 1H and 13C NMR, and MS. Simultaneously, the single crystal structure of the title compound is gauged by X-ray diffraction and subjected to crystallographic and conformational analyses. Density functional theory (DFT) is applied to further calculate the molecular structure and compare it with X-ray values. The result of the conformational analysis shows that the molecular structure optimized by DFT is identical with the single crystal structure determined by single crystal X-ray diffraction. In addition, DFT is used to further study the molecular electrostatic potential and frontier molecular orbitals of the title compound, revealing the molecular structure characteristics, conformation, and some special physical and chemical properties of the title compound. [ABSTRACT FROM AUTHOR]

This paper presents a bounding surface model for unsaturated compacted bentonite based on the critical state theory and bounding surface plasticity. In the proposed model, a shear bounding surface was proposed for describing shear behaviour. A new loading collapse curve was defined to describe suction effects on the yield behaviour. Meanwhile, wetting and drying bounding surfaces were proposed to represent the swelling and shrinkage volume change induced by suction changes. Furthermore, isotropic hardening rule was incorporated into the bounding surface formulation with an associated flow rule. Finally, a simplified form of plastic modulus was introduced to describe elastoplastic behaviour within the bounding surface and the Hvorslev surface was employed to describe the peak strength of heavily compacted bentonite. The proposed model has great potential to realistically describe some features of compacted bentonite including strain hardening or strain softening; monotonic loading under isotropic or one-dimensional compression; yield behaviour due to suction; swelling behaviour induced by changes of suction, etc. With the proposed model, simulations were performed on results of oedometer tests conducted under different suctions, triaxial compression tests and swelling potential tests. Validation showed that good agreements were reached between simulations and the experimental results. A loading collapse bounding surface was proposed to describe the influence of initial dry density on yield stress A shear bounding surface was proposed for describing hardening or softening behaviour The Hvorslev surface was introduced to reflect the peak strength and the water content effect on the peak strength Wetting–drying bounding surface was proposed for describing the volume change induced by suction changes [ABSTRACT FROM AUTHOR]

(2S,2′S,6R,6′R)-4,4′-(6-Bromopyrido[2,3-d]pyrimidine-2,4-diyl)bis(2,6-dimethylmorpholine) is a novel organic intermediate having pyrido[2,3-d]pyrimidine. It is synthesized by four steps and confirmed by 1H and 13C NMR and FTIR spectroscopy and MS. Meanwhile, the single crystal of the title compound is subjected to the crystallographic analysis and the conformation determination. Moreover, density functional theory (DFT) is used to calculate the optimized structures of the molecule which are compared with the X-ray measurement. The result of the molecular structure optimized by DFT is consistent with the crystal structure determined by single crystal X-ray diffraction. Finally, in order to further investigate some physical properties of the title compound by the B3LYP/6-311G(2d,p) method, the molecular electrostatic potential and frontier molecular orbitals are calculated. The calculated and experimental data show that the title compound has good chemical stability and nucleophilic reactivity. Hirshfeld surface analyses can explain the atom pair contacts of the crystal and the quantitative analysis of intermolecular interactions is performed. [ABSTRACT FROM AUTHOR]

Tert-butyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-indazole-1-carboxylate is a significant intermediate of 1H-indazole derivatives. In this paper, the title compound is acquired through two substitution reactions. The structure is corroborated by FTIR, 1H and 13C NMR spectroscopy, and MS. In the meantime, the single crystal is detected by means of X-ray diffraction, calculated by exerting density functional theory (DFT), and subjected to the crystallographic and conformational analysis. The results of comparing the DFT calculated value with the X-ray diffraction value display that the optimized molecular structure does cohere with the single crystal structure ascertained via the experiment. The 98.28% stable conformer and 1.72% unstable conformers are found in the DFT calculations. Furthermore, to reveal the physicochemical features of the title compound, the molecular electrostatic potential and frontier molecular orbitals are investigated through DFT. [ABSTRACT FROM AUTHOR]

Recent research indicates that the estimated elevation changes and associated mass balance in East Antarctica are of some degree of uncertainty; a light accumulation has occurred in its vast inland regions, while mass loss in Wilkes Land appears significant. It is necessary to study the mass change trend in the context of a long period of the East Antarctic Ice Sheet (EAIS). The input-output method based on surface ice flow velocity and ice thickness is one of the most important ways to estimate the mass balance, which can provide longer-term knowledge of mass balance because of the availability of the early satellites in 1960s. In this study, we briefly describe the method of extracting ice velocity based on the historical optical images from 1960s to 1980s. Based on the draft ice velocity map of the EAIS using this method, we conduct a series of validation experiments, including comparisons with in-situ measurement, existing historical maps and rock outcrop dataset. Finally, we use the input-output method to estimate mass balance in some regions of EAIS using the generated velocity map. [ABSTRACT FROM AUTHOR]

Deep geological disposal has been adopted by many countries around the world as a method for disposal of high-level radioactive waste. During the construction and long-term operation of the repository, working as buffer/backfill materials, bentonite will hydrate and swell to fill up various voids in the repository including artificial gaps between canister and compacted bentonite blocks, blocks and blocks, blocks and natural barrier (host rock), etc. More importantly, this closure process will be inevitably affected by groundwater and its chemistry infiltrated. In this study, hydration tests with infiltration of solutions were conducted on GMZ bentonite specimens with artificial annular gaps. The hydration process was monitored by a camera, and the digital images taken were analyzed. Results show that the hydration process for highly compacted GMZ bentonite specimens with an annular gap can be divided into three phases, which can be identified by the development of cracks on the surface of the specimen. In the first phase, bentonite swells and gel generates upon hydration with gradually filling up of the annular gap. While in the second phase, cracks are observed in the center part on the specimen surface, and in the last phase, cracks gradually close up, and eventually disappear accompanied by macroscopic homogenization of the specimen. Different from that for the specimens infiltrated with deionized water, a more rapidly filling up of the artificial annular gap is observed for the specimens injected with salt solutions. Furthermore, with increasing concentration, both of the quantity and width of the cracks formed obviously decrease due to the reduction of both the DDL thickness and electrostatic repulsion forces. Meanwhile, with comparison to that infiltrated with NaCl solutions, a smaller scale of cracks is observed in the dry central part of the specimen infiltrated with CaCl2 solution. Finally, time consumed to reach the macroscopic homogeneous state for the specimen infiltrated with salt solutions is much shorter than that infiltrated with deionized water. Meanwhile, the time required for the specimen infiltrated with CaCl2 solution is shorter than that injected with NaCl solution. Results of the investigation on pore fluid chemistry effects on the swelling behavior of compacted GMZ bentonite with an artificial annular gap could be used for estimation of the sealing effects and time of the technological gaps in the disposal repository, as well as to provide reference for the design and even the final performance evaluation of the engineering barrier system. [ABSTRACT FROM AUTHOR]

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We theoretically demonstrate a polarizer with an electrically controllable polarizing direction in the far infrared range using two orthogonal periodic arrays of graphene ribbons, which have different widths and are supported on a dielectric film placed on a thick piece of metal. The operation mechanism originates from the polarization-dependent resonant absorption of the two orthogonal graphene ribbons, which can be respectively controlled with different external bias voltages. The operation wavelength can be expanded to terahertz (THz) radiation. [ABSTRACT FROM AUTHOR]

The behaviour of plasmonic metal nanoparticles (MNPs) placed in contact with a thin dielectric film on a high refractive index substrate is examined through finite-difference time domain simulations. The optical properties of this configuration are studied in the context of light trapping for thin-film amorphous silicon (a-Si) solar cells. We explore several different MNP configurations including both silver (Ag) and aluminium (Al) nanocubes along with traditional Ag nanospheres for reference. We demonstrate a large increase in the fraction of light coupled into the substrate (Fsubs), and consequently in the absorbed power, by spacing nanocubes away from the substrate. Further study concluded that blue-shifting the plasmonic resonances significantly reduced parasitic absorption in the visible spectrum and increased forward scattering by the MNPs. Transitioning to Al MNPs facilitated a large blue-shift in the plasmonic resonances allowing broadband enhancement in light absorption. For wavelengths less than the band-gap of a-Si, combining the effects of Al nanocubes on a 20 nm SiO2 spacer layer with a 25% surface coverage resulted in a 13.8% increase in solar power absorption over cells with optimally designed Ag nanocube and nanosphere arrays, and a 38.9% enhancement over a MNP free reference cell. [ABSTRACT FROM AUTHOR]

The median time to cutaneous irAE onset was 0.9 months in patients treated with anti-CTLA4/anti-PD-1 combination therapy, compared with 1.7 months and 3.7 months for patients treated with anti-CTLA4 and anti-PD-1 monotherapy, respectively. Overall, 114 patients (58% male, 42% female; mean age 64 years) had experienced cutaneous irAEs following treatment with ICB therapy. [Extracted from the article]

Rationale: Checking is a functional behaviour that provides information to guide behaviour. However, in obsessive-compulsive disorder (OCD), checking may escalate to dysfunctional levels. The processes underpinning the transition from functional to dysfunctional checking are unclear but may be associated with individual differences that support the development of maladaptive behaviour. We examined one such predisposition, sign-tracking to a pavlovian conditioned stimulus, which we previously found associated with dysfunctional checking. How sign-tracking interacts with another treatment with emerging translational validity for OCD-like checking, chronic administration of the dopamine D2 receptor agonist quinpirole, is unknown. Objectives: We tested how functional and dysfunctional checking in the rat observing response task (ORT) was affected by chronic quinpirole administration in non-autoshaped controls and autoshaped animals classified as sign-trackers or goal-trackers. Methods: Sign-trackers or goal-trackers were trained on the ORT before the effects of chronic quinpirole administration on checking were assessed. Subsequently, the effects on checking of different behavioural challenges, including reward omission and the use of unpredictable reinforcement schedules, were tested. Results: Prior autoshaping increased checking. Sign-trackers and goal-trackers responded differently to quinpirole sensitization, reward omission and reinforcement uncertainty. Sign-trackers showed greater elevations in dysfunctional checking, particularly during uncertainty. By contrast, goal-trackers predominantly increased functional checking responses, possibly in response to reduced discrimination accuracy in the absence of cues signalling which lever was currently active. Conclusions: The results are discussed in terms of how pavlovian associations influence behaviour that becomes compulsive in OCD and how this may be dependent on striatal dopamine D2 receptors. [ABSTRACT FROM AUTHOR]

Nonlinear evolution of the ablative Rayleigh–Taylor instability (ARTI) is investigated on the Shenguang-II laser facility using a target specifically designed for this purpose. The evolution of the excited bubbles and spikes is tracked and their displacement amplitudes are quantitatively measured with the help of a Kirkpatrick–Baez microscope coupled with an x-ray framing camera. Radiation-hydrodynamic simulations are qualitatively in agreement with the experiments and demonstrate the phenomenon of bubble acceleration predicted by Betti and Sanz [Phys. Rev. Lett. 97, 205002 (2006)] in the nonlinear evolution of the ARTI. [ABSTRACT FROM AUTHOR]

Background: Medications that are used for treatment of metabolic disorders have been suggested to be associated with the development of amyotrophic lateral sclerosis (ALS). Methods: To examine the associations of antidiabetics and statins with the subsequent risk of ALS we conducted a population‐based nested case‐control study of 2475 Swedish residents diagnosed with ALS during July 2006 to December 2013 and 12 375 population controls (five for each ALS case). We extracted information on filled prescriptions of antidiabetics and statins for both cases and controls from the Swedish Prescribed Drug Register during the years before ALS diagnosis. Conditional logistic regression was used to calculate odds ratios (ORs) for the associations of these medications with ALS risk. Results: Patients with ALS were less likely to have been prescribed with antidiabetics compared with controls [OR, 0.76; 95% confidence intervals (CI), 0.65–0.90]. Conversely, statins were not associated with ALS risk overall (OR, 1.08; 95% CI, 0.98–1.19), although a positive association was noted among women (OR, 1.28; 95% CI, 1.10–1.48). The latter association was mostly explained by ALS cases being more likely to have a first prescription of statins during the year before diagnosis compared with controls (OR, 2.54; 95% CI, 1.84–3.49). Conclusions: The inverse association of antidiabetics with ALS is consistent with the previously reported inverse association between type 2 diabetes and ALS risk. The increase in prescription of statins during the year before ALS diagnosis deserves attention because it might reflect an acceleration of the course of ALS due to statin use. [ABSTRACT FROM AUTHOR]

The fully three-dimensional Rayleigh–Taylor instability in spherical geometry is investigated in the weakly nonlinear regime. A theoretical model is developed for incompressible fluid and ideal Euler equations. Third-order solutions are derived for interface perturbations of spherical harmonic modes, Y n , m . Interface evolution, fundamental mode growth, the generated spectrum, and bubble growth are determined. It is found that the fastest growing modes satisfy the relation m ≃ (n + 1) / 2. The generated spectra demonstrate the feedback of mode coupling, which greatly depends on the azimuthal mode numbers. The growth factors are nearly the same for bubbles at different latitudes and bubbles with initially round cross-sectional perturbation shapes grow faster. [ABSTRACT FROM AUTHOR]

A new species of Paurodontoides , P. siddiqii n. sp., is described and illustrated based on its morphological, morphometric, and molecular characters. The new species is characterized by a female 550–729 μm long, lip region continuous with body contour, stylet length 7.0–8.0 μm long or c. 1.0–1.2 times the lip region diameter, lateral fields with four smooth incisures, excretory pore at 85–125 μm from anterior end located at the base of the pharyngeal bulb or posterior to it, basal pharyngeal bulb with a short posterior extension projecting into the intestine, monodelphic–prodelphic reproductive system with prominent 19–22 μm long post-uterine sac, and elongate conoid tail with a filiform terminus. The new species is compared with two known species of the genus. It differs from the type species of the genus, P. linfordi, by having slightly shorter stylet, lateral field with smooth incisures, different position of the excretory pore, and absence of male. Compared to P. latus , the new species has a shorter body, shorter stylet, different position of the excretory pore, female tail shape and absence of male. The new species was also compared with close species of the genus Paurodontus because of lateral field marked with four lines, asymmetrical stylet knobs and absence of male. Molecular phylogenetic studies of the new species using partial sequences of 18S rDNA revealed that it forms a clade with a species of the genus Ficotylus. In phylogenetic analyses using partial sequences of the 28S rDNA D2-D3 domain, the new species formed a monophyletic group with a species of the genus Veleshkinema and Sphaerularia spp. (Sphaerulariinae). [ABSTRACT FROM AUTHOR]

This paper presents a constitutive model for simulating the swelling–shrinkage volume change of expansive soils during wetting–drying cycles. Based on the concept of the critical swelling–shrinkage state proposed by Zhao et al. [21], the elastic swelling–shrinkage deformation, plastic swelling/shrinkage deformation, and accumulative deformation during wetting–drying cycles were analyzed. Influences of the initial dry density and stress applied on the yield suction were discussed. The suction decreasing yield surface (SD) and suction increasing yield surface (SI) were defined. The variations of SD and SI yield surfaces were proposed. Calibration was performed with results of the cyclic wetting–drying tests conducted. The proposed model was validated by simulating cyclic wetting–drying tests conducted on compacted GaoMiaoZi (GMZ) bentonite. Good agreements were obtained between the simulation results and the experimental ones. Using the proposed model, influences of dry density and stress applied on the swelling–shrinkage deformation and accumulative deformation of expansive soil were well described. [ABSTRACT FROM AUTHOR]

The scaling behaviors of dynamic ferroelectric hysteresis in the relaxor ferroelectric 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (PMNT67/33) ceramics near the morphotropic phase boundary (MPB) and other PMNT systems out of MPB region were investigated. The scaling relation of hysteresis area against frequency f and field amplitude E0 for minor loops takes the form of ∝f-0.2391E04.8779; while for the saturated loops, it is ∝f 0.0401E00.5722. The scaling relations of PMNT67/33 ceramics are significantly different from those of other ferroelectrics, and the results of the analysis indicate that domain reversal in it is much more sensitive to the change of E0 at low electric field and responses more quickly to f at high electric field than other normal ferroelectrics. The coexistence of rhombohedral (R), monoclinic (M) and tetragonal (T) phases near the MPB and the polar nanoregions seems to play the key role in the dynamic behavior of the domain reversal in relaxor PMNT67/33 ceramics. [ABSTRACT FROM AUTHOR]

Three types of dissociated misfit dislocations (MDs) in epitaxial Ba0.3Sr0.7TiO3 thin films grown on (001) LaAlO3 have been studied by high-resolution transmission electron microscopy. First, a MD with b=[101] dissociates into two edge partials and results in the incline of film lattice. Second, a [110] MD is split into two (1/2)[110] partials of mixed character. In the third case, a [110] MD of mixed character is composed of three partials which are reacted with two (1/2)<110> stacking faults. Neither of the three types of dissociation reactions has been reported before for MDs in perovskite thin films. [ABSTRACT FROM AUTHOR]

We have studied the thermoelectric properties of quantum dot (QD) chain nanocomposites in which the QDs are aligned to form chains. In both the InAs/GaAs and Ge/Si systems, we use a constant relaxation time approximation to calculate and compare the electrical conductivity, Seebeck coefficient, and thermoelectric power factor for QD chains, three-dimensional ordered QD arrays, random QD arrays, and bulk GaAs or Si. Our calculations suggest that the incorporation of QD chains into a matrix increases its thermoelectric power factor by a factor of 3 (1.5) for the InAs/GaAs (Ge/Si) system. [ABSTRACT FROM AUTHOR]

We have investigated the mechanisms of GaAs1-xNx film growth by plasma-assisted molecular-beam epitaxy. A comparison of in situ reflection high-energy electron diffraction and scanning tunneling microscopy (STM), with ex situ atomic force microscopy, reveals a temperature-dependent interplay between surface and step-edge diffusion. At low temperatures, layer-by-layer growth is observed, presumably due to limited adatom surface mobility. As the temperature increases, the interplay between surface and step-edge diffusion leads to multilayer growth. For sufficiently high temperatures, adatoms overcome the step-edge diffusion barrier, resulting in layer-by-layer growth once again. The temperature range for multilayer growth is influenced by the Ga flux and may be narrowed by using As2. Using in situ STM, we quantified the activation energies for Ga surface diffusion, Ed, and step-edge diffusion, Ee, during layer-by-layer GaAsN growth. We estimate Ed=0.75 and 0.96 eV for growth using As4 and As2, respectively. Thus, the narrowing of the multilayer growth temperature range is likely due to the decrease in Ga surface diffusion length through the use of As2 in lieu of As4. Furthermore, we estimate Ee=80 meV, larger than what has been reported for GaAs growth. [ABSTRACT FROM AUTHOR]

We have investigated stress evolution in dilute nitride GaAs1-xNx alloy films grown by plasma-assisted molecular-beam epitaxy. For coherently strained films (x<2.5%), a comparison of stresses measured via in situ wafer curvature measurements, with those determined from x-ray rocking curves using a linear interpolation of lattice parameter and elastic constants, suggests significant bowing of the elastic properties of GaAsN. The observed stress differences are used to quantify the composition-dependent elastic constant bowing parameters. For films with x>2.5%, in situ wafer curvature measurements reveal a signature for stress relaxation. Atomic force microscopy and transmission electron microscopy measurements indicate that stress relaxation occurs by a combination of elastic relaxation via island formation and plastic relaxation associated with the formation of stacking faults. [ABSTRACT FROM AUTHOR]

We have examined the matrix-seeded growth of narrow-gap nitride nanostructures in nitrogen ion implanted GaAs and InAs. Low-energy implantation followed by rapid thermal annealing (RTA) results in the formation of 2–3 nm sized amorphous precipitates in a crystalline matrix. On the other hand, high-energy implantation results in an amorphous layer, with or without crystalline remnants. When the ion-beam-synthesized amorphous matrix is a continuous amorphous layer, subsequent RTA leads to the formation of 4–5 nm zinc blende (ZB)-GaN-rich crystallites in an amorphous matrix. When this matrix contains crystalline remnants, subsequent RTA leads to the formation of 2–4 nm ZB-GaN-rich crystallites within the amorphous regions. These results suggest that the matrix plays an important role in the nucleation and growth of narrow-gap nitride nanostructures, and that matrix-seeded growth may provide an opportunity to control the structure and properties of the nanostructures. [ABSTRACT FROM AUTHOR]