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Abstract This paper focuses on the numerical investigation of a strongly nonlinear oscillator with cubic and harmonic restoring force. We transform this oscillator as a free damped cubic-quintic Duffing oscillator equation by Taylor approximation. The approximated solutions with high accuracy are provided by using the global residue harmonic balance method (GRHBM) without any discretization or restrict assumptions. The sensitive analysis of the approximation or the frequency with respect to the amplitude is considered in detail. Numerical comparisons with Runge–Kutta method and harmonic balance method are given to show the efficiency and stability of GRHBM.

Languages can use a common repertoire of vocal sounds to signify distinct meanings. In tonal languages, such as Mandarin Chinese, pitch contours of syllables distinguish one word from another, whereas in non-tonal languages, such as English, pitch is used to convey intonation. The neural computations underlying language specialization in speech perception are unknown. Here, we use a cross-linguistic approach to address this. Native Mandarin- and English- speaking participants each listened to both Mandarin and English speech, while neural activity was directly recorded from the non-primary auditory cortex. Both groups show language-general coding of speaker-invariant pitch at the single electrode level. At the electrode population level, we find language-specific distribution of cortical tuning parameters in Mandarin speakers only, with enhanced sensitivity to Mandarin tone categories. Our results show that speech perception relies upon a shared cortical auditory feature processing mechanism, which may be tuned to the statistics of a given language. Different languages rely on different vocal sounds to convey meaning. Here the authors show that language-general coding of pitch occurs in the non-primary auditory cortex for both tonal (Mandarin Chinese) and non-tonal (English) languages, with some language specificity on the population level.

In this paper, we consider a fractional nonlinear oscillator for a mass attached to a stretched elastic wire. The coupling technique based on the fractional complex transform and the global residue harmonic balance method is proposed for solving this fractional oscillator. The approximated periodic solutions and frequencies are provided without complicated computation and discretization. The frequency–amplitude relationship is investigated to show its monotonic property. Numerical approximations for the nonlinear oscillator with integer or fractional orders are compared with the approximations by some existing methods. Numerical results confirm the effectiveness and robustness of the proposed method.

In tonal languages, which are spoken by nearly one-third of the world’s population, speakers precisely control the tension of vocal folds in the larynx to modulate pitch in order to distinguish words with completely different meanings. The specific pitch trajectories for a given tonal language are called lexical tones. Here, we used high-density direct cortical recordings to determine the neural basis of lexical tone production in native Mandarin-speaking participants. We found that instead of a tone category-selective coding, local populations in the bilateral laryngeal motor cortex (LMC) encode articulatory kinematic information to generate the pitch dynamics of lexical tones. Using a computational model of tone production, we discovered two distinct patterns of population activity in LMC commanding pitch rising and lowering. Finally, we showed that direct electrocortical stimulation of different local populations in LMC evoked pitch rising and lowering during tone production, respectively. Together, these results reveal the neural basis of vocal pitch control of lexical tones in tonal languages. In tonal languages, modulation of pitch distinguishes words with different meaning. Here the authors investigate neural mechanisms of pitch control during lexical tone production in Mandarin-speaking participants.

Converting the lignin into value-added chemicals and fuels represents a promising way to upgrade lignin. Here, we present an effective electrocatalytic approach that simultaneously modulates the depolymerization and hydrogenation pathways of lignin model compounds within a single reaction system. By fine-tuning the pH of the electrolyte, we achieve a remarkable shift in product selectivity, from acetophenone (with selectivity >99%) to 1-phenylethanol (with selectivity >99%), while effectively preventing over-hydrogenation. The robust metallic glass (MG) catalyst, endowed with an amorphous structure, demonstrates high stability, activity, and full recyclability across over 100 consecutive cycles in ionic liquid electrolytes. The relatively strong affinity of the MG catalyst for the substrate during the initial reaction stage, in conjunction with its weaker binding to the phenolic product, as the reaction progresses, creates a delicate balance that optimizes substrate adsorption and product desorption, which is pivotal in driving the cascade hydrogenation process of acetophenone. This work opens versatile pathways for lignin upgrading through integrated tandem reactions and expands the scope of catalyst design with amorphous structures. Lignin valorization has long been hindered by the challenge of precisely controlling product selectivity. Here, the authors construct a robust electrocatalytic system that enables pH-driven switching between depolymerization and hydrogenation pathways with high selectivity.

Stiffness-damping balance, high specific mechanical performance, and corrosion resistance are demanded for metals. Here, we developed an enamel-inspired ceramic (EIC) coating strategy involving hydrothermal growth of a tooth enamel-like ZrO₂ nanorods on Zr foil and amorphous ZrO₂ intergranular phase formation via controlled hydrolysis. The EIC coated Zr foil (Zr-EIC) achieved a high viscoelastic figure of merit (4.6 GPa); as well as excellent specific stiffness and hardness owing to the lightweight of ceramics, surpassing the values of Zr and previously reported Zr-based alloys or Zr-based composites. This was due to the vertically oriented stiff nanorods and unique energy dissipation derived from deformation at the crystalline/amorphous interfaces. It demonstrated exceptional NaCl corrosion resistance. This approach showed universality across Ti, Zn, and Cu substrates, enhancing both mechanical properties and corrosion resistance. By constructing an enamel-like hierarchical structure on the metal surface, the strategy overcomes traditional metal limitations without causing an increase in density. Tooth enamel-inspired ceramic coating (ZrO 2 nanorod and amorphous intergranular phase) enhances Zr foil for lightweight, enhanced mechanical properties and corrosion resistance, and this strategy can be universally applied to Ti, Zn, Cu.

This paper focuses on the numerical investigation of a fractal modification of capillary oscillator by using a coupling technique based on the two-scale transformation and the global residue harmonic balance method. This fractal oscillator can be transformed as the classical capillary oscillator with the help of the two-scale transformation. We further obtain an approximated oscillator by using Taylor approximation. The approximations or frequencies are given by applying the global residue harmonic balance method without discretization. Numerical sensitive analysis of the approximations about different parameters is considered in detail. Compared results with Runge–Kutta method and homotopy perturbation method are given to illustrate the efficiency and stability of the present technology.

Tooth enamel, and especially the outer tooth enamel, is a load-resistant shell that benefits mastication but is easily damaged, driving the need for enamel-restorative materials with comparable properties to restore the mastication function and protect the teeth. Synthesizing an enamel analog that mimics the components and hierarchical structure of natural tooth enamel is a promising way to achieve these comparable mechanical properties, but it is still challenging to realize. Herein, we fabricate a hierarchical enamel analog with comparable stiffness, hardness, and viscoelasticity as natural enamel by incorporating three hierarchies of outer tooth enamel based on hierarchical assembly of enamel-like hydroxyapatite hybrid nanowires with polyvinyl alcohol as a matrix. This enamel analog possesses enamel-similar inorganic components and a nanowire-microbundle-macroarray hierarchical structure. It exhibits toughness of 19.80 MPa m 1/2 , which is 3.4 times higher than natural tooth enamel, giving it long-term fatigue durability. This hierarchical design is promising for scalable production of enamel-restorative materials and for optimizing the mechanical performance of engineering composites. Mechanical compatibility is highly desirable for enamel restorative materials. Here, the authors engineer a hierarchical enamel analog with comparable mechanical properties as outer enamel, showing great potential for enamel restoration.

Direct electrical stimulation (DES) has been widely applied in both guidance of lesion resection and scientific research; however, the design and selection of intraoperative cognitive mapping tasks have not been updated in a very long time. We introduce updated mapping tasks for language and non-language functions and provide recommendations for optimal design and selection of intraoperative mapping tasks. In addition, with DES becoming more critical in current neuroscientific research, a task design that has not been widely used in DES yet (subtraction and conjunction paradigms) was introduced for more delicate mapping of brain functions especially for research purposes. We also illustrate the importance of designing a common task series for DES and other non-invasive mapping techniques. This review gives practical updated guidelines for advanced application of DES in clinical and neuroscientific research.

Sonic hedgehog (SHH) and heat shock protein 90β (HSP90β) have been implicated in nonalcoholic steatohepatitis (NASH) but their molecular mechanisms of action remain elusive. We find that HSP90β is a key SHH downstream molecule for promoting NASH process. In hepatocytes, SHH reduces HSP90β ubiquitylation through deubiquitylase USP31, thus preventing HSP90β degradation and promoting hepatic lipid synthesis. HSP90β significantly increases in NASH mouse model, leading to secretion of exosomes enriched with miR-28-5p. miR-28-5p directly targetes and decreases Rap1b levels, which in turn promotes NF-κB transcriptional activity in macrophages and stimulates the expression of inflammatory factors. Genetic deletion, pharmacological inhibition of the SHH-HSP90β axis, or delivery of miR-28-5p to macrophages in the male mice liver, impairs NASH symptomatic development. Importantly, there is a markedly higher abundance of miR-28-5p in NASH patient sera. Taken together, the SHH-HSP90β-miR-28-5p axis offers promising therapeutic targets against NASH, and serum miR-28-5p may serve as a NASH diagnostic biomarker. The mechanistic involvement of sonic hedgehog signaling in nonalcoholic steatohepatitis is not clear. Here, the authors show that sonic hedgehog protein regulates the stability of HSP90β, enabling hepatocytes to secrete exosomes containing miR-28-5-p to promote NASH development.