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• Nonlinear model for a bended piezoelectric semiconductor beam is established. • Differential quadrature method based iteration procedure is developed. • Nonlinearity of constitutive relation and non-uniformity of structure are focused. • Potential barriers and wells are realized through designing structures. In this paper, the effects of nonlinear constitutive relation on the electro-elastic coupling behaviors in non-uniform piezoelectric semiconductor beams are investigated. On the basis of three-dimensional theory for piezoelectric semiconductor and double power series, one-dimensional bending model is developed. In order to deal with the nonlinear problem, a differential quadrature method based iteration procedure is proposed. Comparing with the results from finite element method, the proposed method has good convergence and high accuracy. In numerical analysis, the effects of nonlinearity and non-uniformity in piezoelectric semiconductor are discussed thoroughly. It is found the introduction of nonlinearity induces the loss of symmetric for all electrical field quantities but little changes the mechanical quantities. While the reduction of width along the length direction produces larger mechanical and electrical responses. Importantly, the effects of nonlinearity on the electrical field quantities are more evident in a piezoelectric semiconductor beam with rapidly varied cross section. Besides, we designed the piezoelectric semiconductor beams subject to double shear forces and a beam with locally varied cross section. In the designed structures, the potential barriers and wells are realized, which provide new approaches adjusting the electro-elastic behaviors in piezoelectric semiconductors. The study in this paper could be the guidance designing high performance electronic devices. [ABSTRACT FROM AUTHOR]

In this paper, a design strategy to keep a pipe away from resonance by adjusting retaining clips is presented. The pipe natural frequency is within the band of vibration frequencies generated by mechanical operation, which can cause the resonance phenomenon. The resonance of pipes could bring serious disaster to the mechanical operation. Therefore, the band of vibration frequencies generated by the mechanical operation is defined as the preserved frequency band (PFB). The pipe in engineering has been simplified to a multispan pipe conveying fluid. An integral pipe model of a multispan pipe conveying fluid is established by simplifying the retaining clips. The natural frequencies of a pipe with clips are obtained. The resonance range and safety range of pipe length are defined as the natural frequencies inside and outside the PFB, respectively. The absolute safety length and the absolute resonance length with respect to clip number are derived. Moreover, the influence of the clip stiffness and location on the safety range is determined. The results show that the safety range is significantly changed by adjusting the vertical stiffness, torsional stiffness, and location of the clips. Based on the results, a pipe design strategy is proposed to stay away from resonance and make for a smaller number of clips. Subsequently, a design for an aircraft pipe is carried out as an example. As a result of the design, the natural frequencies of the aircraft pipe are kept away from the PFB. In summary, a design strategy is obtained to avoid resonance for pipes by adjusting the clip stiffness and/or location. [ABSTRACT FROM AUTHOR]

Transferring gold nanorods (GNRs) from an aqueous solution to a non‐polar solvent enhances self‐assembly, promotes biocompatibility, and boosts surface‐enhanced Raman scattering (SERS). However, the strong attachment ability of toxic hexadecyltrimethylammonium bromide (CTAB) to GNRs presents a significant challenge in the fall of CTAB and combining with other substances for self‐assembly and SERS applications. We propose a solution that employs ethanol as a 'catalyst' to lower the critical micelle concentration (CMC) of CTAB and efficiently combine it with the organosilanes formed by the hydrolysis of mercaptopropyltrimethoxysilane (MPS) and octadecyltrimethoxysilane (ODS). The samples were characterized by UV‐vis‐NIR spectroscopy, transmission electron microscopy (TEM), and energy disperse spectroscopy (EDS) mapping. A detailed interpretation of the phase transfer processes was provided. The modified particles were effectively dispersed in toluene and formed thin films at the air‐water interface through self‐assembly, which was confirmed by scanning electron microscopy (SEM) and optical microscopy. These films can serve as a platform for SERS. [ABSTRACT FROM AUTHOR]

In this study, we synthesized Au-Cu2O core–shell nanoparticles (Au@Cu2O NPs) with epitaxial Cu2O shell, which have highly improved catalytic performances in methyl orange reduction reaction. We have obtained Au@Cu2O NPs with different sizes at low temperatures by changing the amount of Cu2+ precursor. Both Au and Cu2O are catalytic materials, especially Cu2O, as a p-type semiconductor, whose catalytic ability depends on the crystalline facets. Catalytic reduction of methyl orange (MO) was used as a model system to explore the catalytic properties of Au@Cu2O nanocomposite. In comparison to pure Au and Cu2O NPs, the catalytic performance of Au@Cu2O has a noticeable improvement. The best catalytic rate was ~ 22 times faster than that of AuNRs and ~ 4 times than that of Cu2O NPs. By studying the catalytic mechanism, it is supposed that the Schottky barrier at the Au-Cu2O interfaces leads to the charge separation, which is beneficial to catalysis. Therefore, the Au@Cu2O NPs we designed with controllable shell thickness is an ideal composite material in the catalyst domain. [ABSTRACT FROM AUTHOR]

Colletotrichum gloeosporioides, a significant fungal pathogen of crops and trees, causes large economic losses worldwide. However, its pathogenic mechanism remains totally unclear. In this study, four Ena ATPases (Exitus natru-type adenosine triphosphatases), homology of yeast Ena proteins, were identified in C. gloeosporioides. Gene deletion mutants of ΔCgena1, ΔCgena2, ΔCgena3, and ΔCgena4 were obtained through the method of gene replacement. First, a subcellular localization pattern indicated that CgEna1 and CgEna4 were localized in the plasma membrane, while the CgEna2 and CgEna3 were distributed in the endoparasitic reticulum. Next, it was found that CgEna1 and CgEna4 were required for sodium accumulation in C. gloeosporioides. CgEna3 was required for extracellular ion stress of sodium and potassium. CgEna1 and CgEna3 were involved in conidial germination, appressorium formation, invasive hyphal development, and full virulence. The mutant of ΔCgena4 was more sensitive to the conditions of high concentrations of ion and the alkaline. Together, these results indicated that CgEna ATPase proteins have distinct roles in sodium accumulation, stress resistance, and full virulence in C. gloeosporioides. [ABSTRACT FROM AUTHOR]

Digital notch filters are useful for removing sinusoidal signals with a single frequency or multi-frequencies. For some applications, the sinusoidal signals being processed may change frequencies, and thus the notch filter must also have a variable notch frequency. Such a digital filter with a variable notch-frequency (VNF) is called variable notch-frequency (VNF) digital filter. Generally speaking, a VNF filter has the ability to change its notch frequency continuously, and can remove sinusoidal signals with variable frequencies. To design a recursive VNF filter, guaranteeing its stability is the top-priority issue. In this paper, a recursive VNF filter is designed by utilizing the least Lp-norm criterion, and the stability is guaranteed through adopting the stability-guarantee methodology based on parameter transformations. To perform the parameter transformations, a function that meets a special condition is required, and such a function is called unity-bounded function. In this paper, various unity-bounded functions are developed for the parameter-transformation-based stability guarantee. The unity-bounded functions play a crucial role in the stability guarantee. This paper details how to design a stable VNF filter by incorporating the parameter transformations employing the unity-bounded functions into the Lp-norm minimization of the magnitude response. Theoretically, the stability of the recursive VNF filter resulting from the design is definitely guaranteed. Moreover, since the coefficients of the designed VNF are variable, changing the filter coefficients enables the user to get a VNF filter with updated notch frequency. [ABSTRACT FROM AUTHOR]

The roles of CTAB and Ag+ have been discovered and given us a deeper understanding of the seed-mediated method in the gold nanorods synthesis. Former work used binary surfactants CTAB + NaOL (sodium oleate) to greatly improve the dimensional tunability and monodispersity of gold nanorods. However, they only used a few of the concentration combinations of the binary surfactants, and the influence of NaOL under this method has not been systematically studied. In this work, we carried out systematic experiments under the variation of NaOL and used transmission electron microscopy and UV–vis-near-infrared spectroscopy to monitor the growth process of the gold nanorods. The results showed that the NaOL contributed to the symmetry breaking process. We discovered the ideal ranges of NaOL concentration under different concentrations of CTAB (10–40 mM). Lower concentrations of NaOL produced many impurities, such as Au spheres, while higher concentrations of NaOL led to the decrease of monodispersity of the obtained gold nanorods. A growth model based on the balance of diffusion/reduction of the growth solution has been proposed in order to explain the formation of the gold nanorods. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oxygen vacancies was successfully prepared by simple chemical reduction method. • OTC removal efficiency achieved highest of 95.7% in 2.5-OVs-CuFe 2 O 4 /PMS system. • Oxygen vacancies promoted rapid conversion of oxygen into reactive species. • Oxygen vacancies accelerated the conversion of Fe(Ⅱ)/Fe(Ⅲ) and Cu(Ⅰ)/Cu(Ⅱ). • Free radicals of HO , SO 4 − , O 2 – and non-radical of 1O 2 contributed to the OTC degradation. Peroxymonosulfate (PMS) based advanced oxidation methods have gained attention for eliminating antibiotics like oxytetracycline (OTC) from wastewater. This study presents an innovative approach by incorporating oxygen vacancies (OVs) into CuFe 2 O 4 to create OVs-CuFe 2 O 4 materials. Compared to traditional CuFe 2 O 4 , OVs-CuFe 2 O 4 offered superior catalytic performance due to its surface-rich OVs promoting rapid conversion of oxygen and efficient metal redox of Fe(Ⅱ)/Fe(Ⅲ) and Cu(Ⅰ)/Cu(Ⅱ). OVs-CuFe 2 O 4 /PMS achieved impressive 95.7 % OTC removal in 45 min with a rate constant of 0.107 min−1, which was 3.87 times of CuFe 2 O 4 /PMS. The OVs-CuFe 2 O 4 /PMS system exhibited a broad pH tolerance range of 3 to 11 with OTC removal efficiency above 89.3 %. The OVs-CuFe 2 O 4 /PMS system produced various free radicals and non-radical for OTC degradation. The OVs-CuFe 2 O 4 also has good stability with removal efficiency of 81.9 % at fourth cycle. This research gives a strategy to construct oxygen vacancies enrich catalysts for efficient activation of PMS and treatment of antibiotics wastewater. [ABSTRACT FROM AUTHOR]

The mechanism of Au(I)-catalyzed intermolecular annulation of 2-(1-alkynyl)-2-alken-1-one with N-allenamide was carefully elucidated using density functional theory (DFT). The reaction is initiated by the binding of the Au(I) catalyst with 2-(1-alkynyl)-2-alken-1-one rather than with N-allenamide. The key intermediate, a gold all-carbon 1,3-dipole species, is revealed to be more reactive than the gold allylic carbocation. The influence of ligands and substituents was rationally analyzed. We believe that our study will provide deeper mechanistic insights into the chemoselective reactions of alkynes with N-allenamide. [ABSTRACT FROM AUTHOR]

Because of the decrease in the band gap and the carrier recombination rate, the visible light photocatalysis performance of the mixed-phase TiO2 with oxygen vacancies is better than that of the pure-phase TiO2. In this study, two different acids were separately applied in the hydrothermal synthesis of TiO2 nanoparticles without any post-heat treatment. The reaction was carried out at a relatively low temperature not exceeding 140∘C. Both kinds of crystallized TiO2 powders show much more band gap reduction than that of commercial Degussa P25 TiO2 nanoparticles, which can be attributed to the oxygen vacancies. Under the visible light illumination-assisted photocatalytic degradation of methyl orange in water, the two mixed-phase TiO2 powders exhibited a steady photocatalytic activity upon increasing to five cycles. The highest photocatalytic efficiency of the two powders is 2.7 times than that of the P25 powder, which is regarded as an excellent photocatalyst for water purification. Mixed-phase TiO2 nanoparticles were synthesized by acid-assisted hydrothermal synthesis at 140∘C without any post-calcination. Compared with P25, the specific surface area of H-TiO2 (by HCl) and A-TiO2 (by acetic acid) is larger. At the same time, H-TiO2 and A-TiO2 have excellent photocatalytic performances when assisting in the degradation of methyl orange in water under visible light illumination. The stable high photocatalytic performance and the simple preparation methods of the H-TiO2 and A-TiO2 nanoparticles will promote the industrial application. [ABSTRACT FROM AUTHOR]

• A perforated metamaterial plate is proposed for high-density energy harvesting of both acoustic and flexural waves. • Enhanced energy localization and harvesting performance are achieved with larger holes sizes. • The electrical circuit connections exhibit a significant influence on the electricity output. • The electrical boundary conditions can shift the defect band frequency. Metamaterials with defect states are commonly utilized in energy harvesting from acoustic and elastic waves due to their remarkable ability to localize waves. In this study, a novel piezoelectric energy harvester based on a perforated double-pillars metamaterial plate with a point defect, which offers the advantage of efficiently harvesting both ambient acoustic and flexural wave energy, is proposed. The proposed structure incorporates a locally resonant mechanism that enhances the concentration of vibration energy at the defect band frequency. Then, the amplified wave energy is efficiently converted into electrical energy by attaching a piezoelectric patch at the defect position. To initiate this investigation, the differential quadrature method is employed to theoretically estimate the boundary frequencies of the first band gap. Subsequently, this study investigates how holes size, electrical boundary conditions, and electrical circuit connections affect the energy harvesting of both acoustic and flexural waves. Correspondingly, the mechanisms behind their effects are thoroughly explained. Numerical results demonstrate that the wave energy localization performance can be remarkably amplified with an increasing holes radius, and the harvesters with the 1mm holes radius generate voltages that are approximately 2.12 and 1.44 times higher than those with the 0mm holes radius from acoustic and flexural waves, respectively. Furthermore, variations in the defect band frequency and corresponding wave localization behavior depend on the specific electrical boundary conditions and circuit connection approaches, ultimately leading to distinct results in the output electrical energy. These findings present valuable insights and guidelines for the development of high-performance electronic applications in the context of acoustic and elastic wave energy harvesting. [ABSTRACT FROM AUTHOR]

The rainbow trapping effect, characterized by the presence of multiple band gaps (BGs) and wave energy accumulation, holds great promise in applications such as wave filters and vibration energy harvesters. To achieve the tunability of longitudinal wave propagation and further enhanced energy localization, a thickness-induced periodic array of magnetostrictive rods with the rainbow trapping effect is designed in this paper. Firstly, the analysis of longitudinal wave propagation in a periodic non-uniform magnetostrictive rod is conducted using the differential quadrature method, and the correctness is validated by comparing theoretical results with finite element simulations performed for various thickness profiles. Subsequently, according to the combined BGs caused by the proposed metamaterial rods, the formation mechanism of longitudinal wave rainbow trapping is analyzed by time and frequency domain analysis, respectively. Furthermore, the variations in resonance rainbow trapping frequencies are investigated considering the magneto-mechanics coupling in the periodic non-uniform magnetostrictive rods. Numerical simulations demonstrate that resonance rainbow trapping frequencies lead to the most pronounced vibration localization compared to initial and cut-off rainbow trapping frequencies. Notably, the resonance rainbow trapping frequency can be significantly manipulated through applied magnetic field and compressive pre-stress. Those conspicuous phenomena from proposed magnetostrictive metamaterial rods are expected to provide engineers with a new avenue to construct tunable wave filters and vibration signal amplifiers. [ABSTRACT FROM AUTHOR]

The rainbow trapping of elastic wave enables spatial frequency shunting and energy concentration phenomenon, which implies that the broadband vibration will forbid propagating forward and occur energy concentration at different positions of metamaterial structure. This paper proposes a novel metamaterial consisting of the periodic non-uniform Euler-Bernoulli beams with an arbitrary profile section to achieve the rainbow trapping effect of flexural wave and application in piezoelectric energy harvester. Firstly, the differential quadrature method is introduced to solve a partial differential equation with variable coefficients. The convergence of this method is systematically demonstrated, and the correctness of band structures is validated by comparing theoretical results calculated by the differential quadrature method with those from the finite element method for different profiles. Based on band structures analysis, the working mechanism of the flexural wave rainbow trapping effect is attributed to the group velocity modulation; thereby, the constructed periodic array of non-uniform beams achieves integration of specific-band vibration reduction and energy enhancement at specific positions. Secondly, simulations indicate that the resonance rainbow trapping frequencies demonstrate more intense concentration of flexural wave energy compared to the counterpart with initial frequencies. Finally, the resonance rainbow trapping phenomenon demonstrates superiority in vibration energy harvesting. Specifically, when piezoelectric films are pasted on specific-position with enhanced energy density, the maximum output voltage in the independent circuit connection reaches up to 2.30V for the resonance rainbow trapping frequency of 8752Hz and the PVDF film position of x = 670 mm. Furthermore, simulations illustrate that the maximum output voltage and power are up to 4.52V and 1894.12 nW for the Series-A circuit connection, respectively, which is approximately the sum of the individual maximum output electrical energy generated by independent circuit connection at positions A and B. The proposed metamaterial beams can offer new selection guidelines for high-performance vibration energy harvesters. • The flexural wave propagation in a beam with arbitrary contour profiles is solved using the differential quadrature method. • The metamaterial beams with rainbow trapping effect are designed by thickness modulation. • The vibration energy harvesting is realized with the aid of wave trapped. [ABSTRACT FROM AUTHOR]

This paper develops a new method for the design of a recursive allpass phase-compensating system (PCS) with an arbitrarily prescribed stability margin (SM). The design methodology comes from the generalised stability-triangle (GST) that defines a closed stability region for the second-order system, and the closed stability region is described by a pair of parameterised inequalities. Since the GST is developed for the second-order recursive system, to design a high-order PCS, we first construct a high-order PCS using the cascade of a set of second-order systems (sections), and then apply the GST to each of the second-order sections. The two coefficients of each second-order section are first transformed into two new variables by employing a coefficient-transformation technique, and then all the new variables are optimised in such a way that a given phase specification is best approximated. Thanks to both the coefficient transformations and the general stability condition from the GST, the resulting high-order PCS is not only stable, but also satisfies a prescribed SM design specification. This paper includes two examples to illustrate the usefulness of the GST-based PCS design. [ABSTRACT FROM AUTHOR]

• Sequential release hydrogel caters to physiological healing process of periodontium. • The hydrogel can adapt to the complex therapeutic conditions within the oral cavity. • Sequential antibacterial, anti-inflammatory, and bone-promoting properties. • Timely degradability provides a supportive space for alveolar bone regeneration. Periodontitis is a pathological disorder characterized by inflammation and tissue destruction; it is primarily attributed to bacterial infection and immune responses. Nevertheless, existing strategies for drug delivery in periodontal treatment are insufficient to accommodate the intricate anatomical morphology of the periodontium and the complex oral environment. Furthermore, the disordered release of antibacterial agents and bone-promoting substances are not conducive to the natural healing of periodontal tissues, thus resulting in suboptimal therapeutic outcomes for periodontitis. In this study, we successfully co-loaded methylene blue (MB) and poly(lactic-co-glycolic acid) microspheres encapsulating Sema3A into a dopamine-grafted sodium alginate hydrogel (SA-DA). Experimental evidence indicates that MB/Sema3A@SA-DA exhibits favorable injectability, adhesion, and compression resistance characteristics, thus allowing it to adapt to the intricate therapeutic conditions of the oral cavity. The prompt release of MB (within 14 h) demonstrates its high antibacterial efficacy against periodontal pathogens upon exposure to 660 nm light, thereby establishing a microenvironment conducive to osteogenesis devoid of bacterial interference. Furthermore, the protracted release of Sema3A (within 28 d) shows noteworthy osteogenic capabilities and facilitates the polarization of macrophages toward the M2 phenotype. In a rat model of periodontitis, MB/Sema3A@SA-DA can be perfectly applied in situ to local periodontal lesions, and the sequential release of MB and Sema3A effectively achieved antibacterial, anti-inflammatory, and osteogenic effects. This therapeutic system avoids the abuse of antibiotics, surgical trauma, and repetitive administration. Hence, MB/Sema3A@SA-DA emerges as a safe, effective, minimally invasive, comfortable, and cost-effective treatment strategy with considerable potential for clinical implementation in periodontitis management. [ABSTRACT FROM AUTHOR]

The operation of mechanical systems generates vibrations with a certain range of frequencies. Pipes conveying fluid have multiple natural frequencies. It is difficult to avoid one or more natural frequencies of pipes in the operating frequency range of the system, which can lead to resonance and fatigue failure. In this paper, a design strategy to modulate the multi-span pipe's natural frequency by reinforcing pipes with graphene platelets (GPLs) nanofiller is proposed to solve the pipe resonance in engineering. The multi-span functionally graded (FG) pipe is constructed based on an integral pipe model with GPLs uniformly or non-uniformly distributed in the metal matrix. The effective properties of the nanocomposite are determined by using the Halpin-Tsai micromechanics model and rule of mixture. Subsequently, the safety range and resonance range of the multi-span FG pipe are obtained by comparing the first tenth-order natural frequency and preserved frequency band. A comprehensive investigation on the effect of patterns, weight fraction, and geometric parameters of GPL is conducted to identify the most effective way to modulate the pipe's natural frequency. The results indicate that GPL weight fraction is able to modulate the multi-span pipe's natural frequency and safety range over a wide range. In addition, the natural frequency and safety range of the FG pipe reinforced with GPLs increase as the stiffness and number of retaining clip increase. Based on the results, a pipe design strategy with fewer retaining clips is proposed for pipes away from resonance by reinforcing pipes with GPL nanofiller. In the case of an aircraft hydraulic pipe, the natural frequency of the pipe reinforced with GPLs is far away from the preserved frequency band and without resonance in operation. In summary, the design strategy of pipe reinforced with GPLs shed important insights on reducing the vibration level of multimodal structures. • Graphene platelet weight fraction is able to modulate the pipe's natural frequency over a wide range. • A new concept of frequency preserve is proposed for pipe design with low vibration level. • A design strategy for pipes away from resonance by graphene platelets nanofiller is presented. • The proposed design strategy avoids resonance of pipes and makes for a smaller number of clips. [ABSTRACT FROM AUTHOR]

Metamaterials, subwavelength nanostructured materials, can exhibit novel optical properties such as a negative index of refraction. Dielectric core–nanoparticle satellite clusters, termed "metamolecules," can have strong optical magnetic resonances in the visible wavelength range—a requirement to achieve negative refractive index materials. However, achieving the desired photonic properties is challenging due to limited control in forming the metamolecule structures. Here, polystyrene (PS) core–gold nanoparticle (AuNP) satellite metamolecules with highly ordered single layers (monolayers) of AuNPs are fabricated and single particle spectroscopy, electron tomography structural measurements, and electrodynamics simulations are conducted to study the photonic properties of metamolecules constituted of ≈100 AuNPs. The simulated and experimental spectra of the many metamolecules studied, including excitation with azimuthally and radially polarized light, are in excellent agreement. It is shown that the scattering properties of the metamolecules are dominated by the AuNPs near the "equator" of the cluster, and that backscattering is strongly suppressed when different multipolar modes (e.g., dipolar and quadrupolar) of electric or optical magnetic character have comparable intensity due to the π‐phase shift of their scattering. Both the optical excitation fields and the ordering of the nanoparticles within metamolecules affect their optical excitation and scattering properties, providing new insights into designing novel photonic metamaterials. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (Ag NPs) have become one of the current research hotspots and are used in many fields such as electrochemistry, energy, bioanalysis, and environmental monitoring, especially in the field of antibacterial research. In this study, we investigated the effect of properties of Ag NPs coated with polar materials. Ag NPs covered by a dispersant that was triethylene glycol monoethyl ether was stable and conquered the aggregation of Ag NPs. The effect of the dispersant on biocompatibility was explored through interaction experiments between Ag NPs and DNA sequence. The coated Ag NPs could adsorb DNA, and the fluorescence of FAM-DNA could be quenched by Ag NPs. The adsorption and desorption experiments of DNA showed that the order of DNA functional groups on the interaction process was phosphate>T>C>A>G. Moreover, we selected marine pathogenic bacteria to test the antibacterial effect of Ag NPs coated with a polar dispersant. The polar material had a certain inhibitory effect on the antibacterial activity of Ag NPs. However, small molecules such as bases could interact on the surface Ag NPs and release Ag+ to perform the antibacterial activity. The results could contribute to the further application of Ag NPs. [ABSTRACT FROM AUTHOR]

Mesoporous silica nanoparticles (MSNs) functionalized with redox‐sensitive or pH‐sensitive nanovalves for doxorubicin delivery and release by using recombinant human H chain ferritin (HFn) as a cap have been designed and fabricated. In both cases, transmission electron microscope observatory, dynamic light scattering change, Fourier transform infrared spectra examination, thermogravimetric analysis show that HFn can be chemically bonded to MSNs while retaining its ability to target transferrin receptor 1 (TfR1). Cargo loading and release studies demonstrate that HFn is an efficient capping agent, blocking the pores of MSN preventing cargo molecules from diffusing out, and is responsive to redox stimuli or pH changes. More importantly, HFn can not only cap the MSNs, but also enables targeted cargo delivery to malignant cells by binding to the TfR1 that has been overexpressed in various tumors, which can be reflected by the cell viability and fluorescence microscope analysis results comparing with cyclodextrin as the capping agent and TfR1 blocking assay. The in vivo study reveals the excellent efficacy of doxorubicin loaded and HFn capped MSNs on suppression of tumor growth. The new developed drug delivery system features mutually benefit and mutually support, providing strategy for achieving specific‐site therapeutics delivery systems. [ABSTRACT FROM AUTHOR]

Multimetallic plasmonic nanostructures, with appropriate morphology, elemental proportions and sizes, can be used to accelerate photocatalytic reactions. Here, we designed zigzag trimetallic nanostructures with the Au core and Pd–Pt alloy shell, whose catalytic ability was boosted by the synergistic effect of the plasmonic metal and catalytic metal. The catalytic rate of Au@PdPt nanoparticle (NP) with no light have a significant improvement, attributed to the larger contact area provided by the zigzag alloy shell. Furthermore, the enhanced catalytic activity in the presence of light is primarily due to the thermo-photo catalytic effect of plasmonic Au. The adding ratios of Pd:Pt were adjusted from 1:4 to 4:1, and we found that, when adding the Pd:Pt of 1:1, the zigzag Au@PdPt nanoparticle (NP) exhibited a superior reaction rate in the reduction methylene blue (MB) under light illumination. The rate is 8 times higher than that of Au@Pt, and the reduction conversion reached 100%. And it has a favorable plasmon enhancement factor with an appropriate shell thickness and get the balance between the catalytic performance and economic effects. This structure driven by capability-oriented design principles and holds the potential for applications in the field of catalysis. [ABSTRACT FROM AUTHOR]

• Brake pedal force are higher than the accelerator pedal force. • The pedal force is positively correlated with the HRI, and this correlation for brake pedal is stronger. • The correlation between averaged HRI and averaged pedal force on sloped is stronger than individuals. • There is no significant correlation between gradient of sloped section, brake pedal use frequency and HRI. Sloped sections are the basic road units of mountain roadways and often considered as high-risk positions. To verify the correlation between the slope and the physiological signals of drivers and thus acquire the mechanism of the influence of the slope parameters on the drivers' workload, this study conducted naturalistic driving tests on two-lane mountainous roads. The data of vertical alignment parameters, electrocardiographic signals of drivers, and accelerator/brake pedal forces were collected. The distribution pedal force as well as its relation with the heart rate increase (HRI) were analyzed. Furthermore, the mechanism of drivers' workload on slopes was identified in terms of the physical and mental burden. The main findings are as follows. (1) Brake pedal force are higher than those of the accelerator pedal force, and the amplitude of the brake pedal force corresponding to the maximum use frequency is higher than that of accelerator pedal force, i.e., greater physical load is required for foot-operated control on downhill segments. (2) The pedal force is positively correlated with the HRI, and the correlation between brake pedal force and HRI is stronger than accelerator pedal. (3) There is no significant correlation between gradient of sloped section, HRI and brake pedal use frequency. (4) When the HRI and pedal force data collected from different drivers on a slope were averaged, the correlation between HRI and pedal force was found to be even stronger. [ABSTRACT FROM AUTHOR]

Periodic high-intensity focused ultrasound modulation of a nanoparticle generates reversible MRI T1 relaxivity changes at the 1.5 mm3 focal point causing periodic T1-weighted signal changes. Fourier analysis extracts signal changes at the modulation frequency, and a modulation enhancement map spotlights the precise region of interest by increasing contrast almost 100-fold. [ABSTRACT FROM AUTHOR]

• The large specific heat region benefits the heat transfer of supercritical fluid. • The working point is proposed to evaluate the overall heat transfer performance. • The validation of this method is performed in a double pipe heat exchanger. • The heat transfer coefficient is higher when the working point is closer to 1. Printed circuit heat exchangers are considered as one of the most promising candidates for the supercritical carbon dioxide Brayton cycle due to its high pressure resistance and high compactness. It is a critical component to exchange the heat between the primary loop and the secondary loop, which directly relates to the overall efficiency of the Brayton cycle. This work investigates the effect of supercritical carbon dioxide side inlet temperature and pressure on the overall heat transfer performance of a printed circuit heat exchanger with zigzag fins. A new evaluation method with working point is proposed to estimate the overall heat transfer performance, which considers the effects of working temperature and pressure. The results show that the overall heat transfer coefficient increases with the increase of mass flow rate and operating pressure, but performs the opposite changes with the increase of inlet temperature. A printed circuit heat exchanger will get better performance when the working point is closer to 1. This evaluation method is further validated under different operating conditions with available data from the open literature. The results show that the overall heat transfer coefficient peaks when the working point is closer to 1 for a double pipe heat exchanger. [ABSTRACT FROM AUTHOR]

The experiment is conducted with a high-speed camera to investigate the breakup processes of liquid jets in uniform, shear-laden, and swirling cross-airflows. The liquid used in the test is water, the nozzle diameter is 2 mm, and the liquid-to-air momentum flux ratio q ranges from 5 to 3408.5. The results indicate that liquid jets break up to form small droplets in the uniform cross-airflow. There is an exponential relation between the broken position and q. In the shear-laden cross-airflow, the penetration depth of the jet is similar to that of the uniform case, both of which increase with the increase of q. When q and the mean Weber number are the same as the uniform case, the penetration depth of the jet increases by 25% when the velocity ratio of the upper and lower inlets is UR=5; the jet penetration depth decreases by 47.2% when the ratio of UR=0.2 and the jet breaks up quickly and the atomization effect will be better. In the swirling cross-airflow, the jet trajectory is similar to the uniform case and also satisfies the exponential property. When the swirl is weak (swirling number SN=0.49), the jet penetration depth increases compared to the uniform case; when the swirl is strong (SN=0.82), the cross-swirling airflow restrains the jet penetration depth. [ABSTRACT FROM AUTHOR]

This paper proposes a novel method for the design of a recursive second-order (biquadratic) all-pass phase compensator with controllable stability margin. The design idea stems from the generalized stability triangle (GST) derived by the author for the second-order biquadratic digital filter. Based on the GST, a parameter-transformation method is proposed on the transformations of the denominator coefficients of the transfer function of the biquadratic phase compensator. The transformations convert the original denominator coefficients to other new parameters, and any values of those new parameters can guarantee that the GST condition is always satisfied. Optimizing the new parameters yields a biquadratic phase compensator that definitely meets a prespecified stability margin. That is, a biquadratic all-pass phase compensator can be designed to have an arbitrarily specified stability margin. This in turn avoids the occurrence that a recursive phase compensator may become unstable in the practical applications. Thus, the resulting biquadratic phase compensator has robust stability, which is extremely important during the practical filtering operations. A design example is given to show the stability margin guarantee as well as the approximation accuracy. [ABSTRACT FROM AUTHOR]

Due to its wide monitoring range and low cost, visual-based fire detection technology is commonly used for fire detection in open spaces. However, traditional fire detection algorithms have limitations in terms of accuracy and speed, making it challenging to detect fires in real time. These algorithms have poor anti-interference ability against fire-like objects, such as emissions from factory chimneys, clouds, etc. In this study, we developed a fire detection approach based on an improved YOLOv5 algorithm and a fire detection dataset with fire-like objects. We added three Convolutional Block Attention Modules (CBAMs) to the head network of YOLOv5 to improve its feature extraction ability. Meanwhile, we used the C2f module to replace the original C2 module to capture rich gradient flow information. Our experimental results show that the proposed algorithm achieved a mAP@50 of 82.36% for fire detection. In addition, we also conducted a comparison test between datasets with and without labeling information for fire-like objects. Our results show that labeling information significantly reduced the false-positive detection proportion of fire-like objects incorrectly detected as fire objects. Our experimental results show that the CBAM and C2f modules enhanced the network's feature extraction ability to differentiate fire objects from fire-like objects. Hence, our approach has the potential to improve fire detection accuracy, reduce false alarms, and be more cost-effective than traditional fire detection methods. This method can be applied to camera monitoring systems for automatic fire detection with resistance to fire-like objects. [ABSTRACT FROM AUTHOR]

Reference 1 Deng T.-C., Yang J.-Y., Sun M.-L., Zhang Y.-Z., Pan Y.-T., Huang L. Distinct roles of Ena ATP family proteins in sodium accumulation, invasive growth, and full virulence in Colletotrichum gloeosporioides. Graph Footnotes 1 B Disclaimer/Publisher's Note: b The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). Distinct Roles of Ena ATP Family Proteins in Sodium Accumulation, Invasive Growth, and Full Virulence in Colletotrichum gloeosporioides. [Extracted from the article]

This paper proposes a two-step strategy for designing a variable-bandwidth (VBW) digital filter through minimizing the -norm of the magnitude-response error. This -norm design can be regarded as a generalized version of the existing weighted-least-squares (WLS) design. Equivalently, the WLS design is a special case of the -norm-minimization design for . This paper discusses the design of the recursive VBW filter with the transfer function whose denominator is expressed as the product of the second-order sections. As long as all the second-order sections are stable, the recursive VBW filter is also stable. To ensure that the designed recursive VBW filter is stable, we adopt the coefficient-conversion strategy that constrains all the denominator-parameter pairs of the second-order sections within the stability triangle. This paper also proposes a novel conversion function for performing the coefficient conversion. As a consequence, the designed VBW filter is definitely stable. A bandpass VBW filter is designed for showing the feasibility of the -norm-minimization-based design and verifying the stability guarantee. [ABSTRACT FROM AUTHOR]

The maximally flat variable-delay (VD) digital filter can be derived by using the discrete-Pascal-transform (DPT) and the DPT-based Pascal-polynomial interpolation. In this paper, we develop an efficient structure for the low-complexity and high-modularity implementation of this Pascal-type VD filter. As compared to other existing filter structures, this new structure greatly reduces the multiplication operations required in the filtering process. Roughly speaking, the proposed new structure can reduce the multiplication operations by almost one-third. Thus, this new filter structure has the lowest filter complexity among all the existing filter structures for the implementation of the maximally flat VD filter. As a result, signal interpolation can be efficiently performed through utilizing this new filter structure. As opposed to other existing structure with transient problem, we will show that the proposed new structure does not involve any transient problem. That is, it is a transient-free structure. Consequently, the proposed new filter structure can achieve more accurate signal-interpolation results than other structures that have the transient problem. Finally, we show that this proposed structure also has high modularity and it is suited for modularized hardware implementation. [ABSTRACT FROM PUBLISHER]

Existing optical fire smoke detectors would take more time or even fail to trigger alarms of black smokes because the optical scattering efficiencies of black smokes are much lower than those of white smokes. In this paper, we design an optical fire smoke detector with consistent response to white smokes and black smokes based on dual-wavelength technology and multiple scattering signals. The proposed detector utilizes the incident lights of dual wavelengths to measure the surface area concentration and volume concentration of fire smokes respectively. The particle size distribution of the smokes can be estimated by these concentrations. The refractive indices are deduced by the third scattering signal and more observing angles are helpful to reduce the measurement errors. As a result, a 4-channel detector [140°–950 nm, 45°–950 nm, 140°–450 nm, 45°–450 nm] is developed, which can accurately measure the concentrations of both smoldering cotton (white smoke) and open fire of polyurethane (black smoke). [ABSTRACT FROM AUTHOR]

This paper proposes an iterative strategy employing the linear programming (LP) method for the design of an all-pass variable-phase (AP-VP) digital filter in the minimax error sense. Mathematically, designing an AP-VP digital filter belongs to a non-linear optimisation problem. The novel LP design method first reduces this non-linear minimisation problem to a linear minimisation problem and then solves the linearised optimisation problem iteratively via using the LP method. The iterative LP-solving scheme is able to reduce the largest design errors significantly and thus can get a considerable accuracy improvement as compared to the noniterative one. We will utilise three design examples to show that this iterative scheme can get much better design results (much smaller maximum errors) than the noniterative method in the literature. Therefore, this iterative LP design strategy can significantly enhance the performance of the AP-VP digital filter. [ABSTRACT FROM AUTHOR]

Antibiotic resistance is becoming a global threat and overuse of antibiotics in aquaculture disease control worsens the situation. To reduce the risk of drug resistance developed in aquaculture, safer biocontrol programs are needed. Antivirulence therapy, with less chance for developing drug resistance, is a promising approach. To facilitate antivirulence inhibitor design against Vibrio anguillarum , a serious aquaculture pathogen, we present crystal structures for isochorismatase domains of AngB and VabB, which are required to synthesize siderophore, a critical virulence factor. Both structures are highly similar to known isochorismatases in fold and active site, therefore we conclude inhibitors for isochorismatases can be developed in a common framework. The structural information will improve design of virulence inhibitors against Vibrio anguillarum . We also firstly report that isochorismatase family could bind endogenous metabolite during the hetero-expression process, which is likely nicotinic acid, nicotinamide or pyrazinic acid, based on structural analysis and affinity prediction. Taken together, our results provide precise structural information of isochorismatase domains for antivirulence inhibitor design against Vibrio anguillarum . [ABSTRACT FROM AUTHOR]

This paper proposes a frequency-domain method for designing a wide-band length-8 interpolator in the weighted-least-squares (WLS) sense. The length-8 interpolator is even-symmetric and it consists of the fourth-order piecewise polynomials. In this paper, we first present a simple method for deriving its closed-form frequency response, and then formulate a frequency-domain WLS design with the C0-continuity constraint. Since the length-8 interpolator contains a total of 20 parameters, and the C0-continuity imposes 8 constraints on the design, the remaining 12 parameters can be taken as free parameters. After expressing the frequency response as the function of the 12 free parameters, the optimal free parameters can be found in the frequency-domain by minimizing the weighted squared error between the ideal and actual frequency responses, where a non-negative weighting function is adopted for emphasizing important frequency bands and ignoring unimportant bands. Consequently, the WLS design can yield an extremely accurate wide-band length-8 interpolator. Three interpolation examples are given to verify that the designed length-8 wide-band interpolator can achieve the highest accuracy in both the frequency-domain and time-domain as compared to other existing interpolators. [ABSTRACT FROM AUTHOR]

To explore the exact electric properties and reveal the intrinsic interaction mechanisms among multi-fields in composite magneto-electric-semiconductor structures, two-dimensional analyses are performed based on the coupled field theory. Expanding the basic physical quantities to Fourier series along the length, the governing equations are simplified. And then, the discrete solutions are derived by utilizing differential quadrature method. As applications, three composite structures are designed via considering different poling directions. Respectively, the extension, piecewise deformation and bending are realized. Before analysis, the convergence and correctness of adopted method are discussed systematically. In numerical calculation, the effect of material proportion on the perturbation carrier density is investigated. It is found the variation rule of perturbation carrier density is controlled by material proportion and deformation form simultaneously. Importantly, there are optimal material proportion ranges producing the carriers, nevertheless, the ranges are different for three structures. Additionally, two-dimensional distributions of perturbation carrier density, electric field, electric displacement and polarization are discussed. Along the thickness, the field quantities are symmetric for extension and piecewise deformation, but is antisymmetric for bending. Specially, in the structure with piecewise deformation, the potential barriers are realized. This work could be the guidance designing magneto-electric devices. [ABSTRACT FROM AUTHOR]

Guaranteeing the stability is one of the most critical issues in designing a variable recursive digital filter. In this paper, we first present an odd-order recursive variable model (transfer function) that is used for designing an odd-order variable-magnitude (VM) digital filter, and then we replace the original coefficients of the denominator of the odd-order transfer function with a set of new parameters. These new parameters can ensure that they can take arbitrary values without incurring instability of the designed odd-order VM filter. To make the VM filter coefficients variable, we find all the VM filter coefficients as polynomial functions of the tuning parameter, which includes two phases. The first phase designs a set of recursive digital filters with fixed coefficients (constant filters), and the second phase utilizes a curve-fitting scheme to represent each coefficient as a polynomial function. As a result, the VM filter coefficients become variable, and the proposed parameter-substitution-based denominator coefficients ensure the filter stability. This is the most important contribution of the parameter-substitution-based design scheme. This paper uses the fifth-order demonstrative example to verify the stability guarantee as well as the design accuracy of the obtained the fifth-order VM filter. [ABSTRACT FROM AUTHOR]

Stability is one of the most concerned issues in designing a recursive variable digital filter (VDF). This is because the coefficients of a recursive VDF constantly vary in the tuning process, and updating the coefficients may incur instability. Thus, an appropriate measure needs to be taken for ensuring its stability. This paper presents a new coefficient transformation (CT) method for transforming the coefficients of a recursive transfer-function denominator into a set of new coefficients. From the viewpoint of conventional constant-coefficient filter (constant filter) design, the new coefficients can take arbitrary values without incurring instability. For designing a stable VDF, we apply this CT to the variable case and approximate each transformed coefficient as a distinct polynomial in the tuning parameter. Thus, we can change the filter coefficients by changing the value of the tuning parameter, and thus tune the magnitude response. Thanks to the proposed CT, updating the filter coefficients will never incur instability. This is the core part of the CT-based design approach. In this paper, we utilise a weighting function to ignore the transition-band errors and thus enhance the design accuracy of important frequency bands (passband and stopband). Moreover, the polynomials use different degrees so as to reduce the VDF complexity. Two design examples (lowpass VDF and bandpass VDF) are provided for verifying the design accuracy and checking the stability. [ABSTRACT FROM PUBLISHER]

The surface area concentration and the volume concentration of aerosols can be used to detect fire smoke. However, existing optical sensors with a single wavelength source cannot measure these two concentrations accurately. In this paper, we design a sensor to measure these two concentrations with dual wavelength sources, based on the phenomenon that the surface area concentration and the volume concentration of aerosols are proportional to the scattering intensity of the different wavelength incident lights. The prototype sensor is tested by monodisperse aerosols with particle sizes ranging from 200 nm to 2000 nm. The standard measurement deviations of the surface area concentration, volume concentration and Sauter mean diameter are 11.6%, 21.9% and 9.4%, respectively, which are better than the results of sensors with a single wavelength source. Moreover, the Sauter mean diameter of fire smokes measured by our sensor are consistent with calibration instruments, which is helpful to resist false alarm in fire detection. With simple mechanical structure and high accuracy, this sensor is promising in fire detection and atmosphere environment monitoring. [ABSTRACT FROM AUTHOR]

An interpolation kernel is required in a wide variety of signal processing applications such as image interpolation and timing adjustment in digital communications. This article presents a general-form interpolation kernel called 3-3-3 interpolation kernel and derives its frequency response in a closed-form by using a simple derivation method. This closed-form formula is preliminary to designing various 3-3-3 interpolation kernels subject to a set of design constraints. The 3-3-3 interpolation kernel is formed through utilising the third-degree piecewise polynomials, and it is an even-symmetric function. Thus, it will suffice to consider only its right-hand side when deriving its frequency response. Since the right-hand side of the interpolation kernel contains three piecewise polynomials of the third degree, i.e. the degrees of the three piecewise polynomials are (3,3,3), we call it the 3-3-3 interpolation kernel. Once the general-form frequency-response formula is derived, we can systematically formulate the design of various 3-3-3 interpolation kernels subject to a set of design constraints, which are targeted for different interpolation applications. Therefore, the closed-form frequency-response expression is preliminary to the optimal design of various 3-3-3 interpolation kernels. We will use an example to show the optimal design of a 3-3-3 interpolation kernel based on the closed-form frequency-response expression. [ABSTRACT FROM PUBLISHER]

Long-term metformin treatment reduces the risk of stroke. However, the effective administration pattern and indications of metformin on acute cerebral ischemia are unclear. To investigate the neuroprotective treatment duration and dosage of metformin on focal ischemia mice and the association of neuroprotection with 5′-adenosine monophosphate-activated protein kinase (AMPK) regulations, male C57BL/ 6 mice were subjected to permanent or transient middle cerebral artery occlusion (MCAO) and metformin of 3, 10 and 30 mg/kg was intraperitoneally injected 1, 3 or 7 days prior to MCAO, or at the onset, or 1, 3 or 6 h after reperfusion, respectively. Infarct volumes, neurological deficit score, cell apoptosis, both total and phosphorylated AMPK expressions were assessed. Results showed that prolonged pretreatment to 7 days of metformin (10 mg/kg) significantly ameliorated brain infarct, neurological scores and cell apoptosis in permanent MCAO mice. Shorter (3 days or 1 day) or without pretreatment of metformin was not effective, suggesting a pretreatment time window. In transient MCAO mice, metformin showed no neuroprotection even with pretreatment. The expressions of total and phosphorylated AMPK were sharply decreased with effective metformin pretreatments in ischemic brains. Our data provided the first evidence that in acute ischemic injury, a 7-days pretreatment duration of 10 mg/kg metformin is necessary for its neuroprotection, and metformin may not be beneficial in the cases of blood reperfusion. [ABSTRACT FROM AUTHOR]

In the design of recursive digital filters, the stability of the recursive digital filters must be guaranteed. Furthermore, it is desirable to add a certain amount of margin to the stability so as to avoid the violation of stability due to some uncertain perturbations of the filter coefficients. This paper extends the well-known stability-triangle of the second-order digital filter into more general cases, which results in dented stability-triangles and generalized stability-triangle. The generalized stability-triangle can be viewed as a special case of the dented stability-triangles if the two upper bounds on the radii of the two poles are the same, which is a generalized version of the existing conventional stability-triangle and can guarantee the radii of the two poles of the second-order recursive digital filter below some prescribed upper bound. That is, it is able to provide a prescribed stability-margin in terms of the upper bound of the pole radii. As a result, the generalized stability-triangle increases the flexibility for guaranteeing a prescribed stability-margin. Since the generalized stability-triangle is parameterized by using the upper bound of pole radii, i.e., the stability-margin is parameterized as a function of the upper bound, the proposed generalized stability-triangle facilitates the stability-margin guarantee in the design of the second-order as well as high-order recursive digital filters. [ABSTRACT FROM AUTHOR]

Cyclodextrins (CyDs) in nano drug delivery systems have received much attention in pursuit of good compatibility, negligible toxicity, and improved pharmacokinetics of drugs. Their unique internal cavity has widened the application of CyDs in drug delivery based on its advantages. Besides this, the polyhydroxy structure has further extended the functions of CyDs by inter- and intramolecular interactions and chemical modification. Furthermore, the versatile functions of the complex contribute to alteration of the physicochemical characteristics of the drugs, significant therapeutic promise, a stimulus-responsive switch, a self-assembly capability, and fiber formation. This review attempts to list recent interesting strategies regarding CyDs and discusses their roles in nanoplatforms, and may act as a guideline for developing novel nanoplatforms. Future perspectives on the construction of CyD-based nanoplatforms are also discussed at the end of this review, which may provide possible direction for the construction of more rational and cost-effective delivery vehicles. [ABSTRACT FROM AUTHOR]

Quantitative reverse transcription PCR (qRT-PCR) is a sensitive technique used in gene expression studies. To achieve a reliable quantification of transcripts, appropriate reference genes are required for comparison of transcripts in different samples. However, few reference genes are available for non-model taxa, and to date, reliable reference genes in Cycas elongata have not been well characterized. In this study, 13 reference genes (ACT7, TUB, UBQ, EIF4, EF1, CLATHRIN1, PP2A, RPB2, GAPC2, TIP41, MAPK, SAMDC and CYP) were chosen from the transcriptome database of C. elongata, and these genes were evaluated in 8 different organ samples. Three software programs, NormFinder, GeNorm and BestKeeper, were used to validate the stability of the potential reference genes. Results obtained from these three programs suggested that CeGAPC2 and CeRPB2 are the most stable reference genes, while CeACT7 is the least stable one among the 13 tested genes. Further confirmation of the identified reference genes was established by the relative expression of AGAMOUSE gene of C. elongata (CeAG). While our stable reference genes generated consistent expression patterns in eight tissues, we note that our results indicate that an inappropriate reference gene might cause erroneous results. Our systematic analysis for stable reference genes of C. elongata facilitates further gene expression studies and functional analyses of this species. [ABSTRACT FROM AUTHOR]

This paper first derives a simplified variable-fractional-delay (VFD) expression for the all-pass (AP) VFD digital filter, and then uses the simplified VFD expression to formulate the minimax AP-VFD filter design as a two-step linear-programming (LP) problem. To suppress the maximum error of the VFD response (VFD-peak-error), this minimax design minimizes the maximum error of the variable-frequency-response (VFR) subject to the VFD-peak-error constraint. Thus, this two-step design can minimize the VFR-peak-error with the VFD-peak-error suppressed below a prescribed upper bound. With the aid of the simplified VFD expression, the VFD-peak-error constraint can be approximately linearized as a linear one, and thus the minimax design can be solved by using the LP method. We will use an illustrative example to verify that the simplified VFD expression is almost the same as the true one, and that the proposed LP-based two-step minimax design can significantly suppress the VFD-peak-error. [ABSTRACT FROM AUTHOR]

To design a variable recursive digital filter whose stability is always guaranteed, it is necessary to ensure that the stability conditions are always satisfied in the tuning process. Furthermore, it is also necessary to keep a certain margin for the stability (stability margin) in such a way that some unpredictable environmental changes and coefficient-value deviations will not cause instability. To add a stability margin to the stability of the second-order (2nd-order) recursive filter, this paper first introduces a stability trapezoid by trimming the well-known stability triangle of the 2nd-order recursive digital filter. Then, we quantitatively analyze the upper bound for the stability margin by using a stability-margin parameter. This theoretical stability-margin analysis is fundamental to the design of a variable recursive filter with an expected stability margin. Finally, we utilize a demonstrative example to verify the consistence between the theoretical upper bound of the stability margin and the computer simulation results. [ABSTRACT FROM AUTHOR]

The samarium-doped ceria (SDC) nanospheres were prepared by the one-step hydrothermal method and characterized by transmission electron microscope, scanning electron microscope, powder X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive spectrometer and Raman spectra. According to the results, samarium was doped into the lattice successfully. The as-prepared samples were dispersed well and the average diameter was 60 nm. It showed better catalytic performance than pure ceria and the most appropriate concentration of doping was found. [ABSTRACT FROM AUTHOR]

• The integral-model and the two-span model of a pipe with a retaining clip are established respectively. • Critical velocity and natural frequencies of fluid-conveying pipes with a retaining clip are obtained. • Variations in the clip stiffness can cause different types of non-trivial equilibria of the pipe. • Natural frequencies of the pipe can be adjusted in a wide range by changing the clip position. Although retaining clips are widely used to constrain high-velocity fluid-conveying pipes, there are few studies on the influence of retaining clips on the supercritical vibration characteristics of the pipes. In this study, the vibration characteristics of the fluid-conveying pipe with retaining clip are firstly presented in the supercritical regime. According to the generalized Hamiltonian principle, the governing equation of the fluid-conveying pipe with the retaining clip is derived. When the flow velocity exceeds the critical velocity, the equilibrium configuration of the pipe becomes the non-trivial static equilibrium configuration. By coordinate transformation, the governing equation of the supercritical pipe around the non-trivial static equilibrium configuration is obtained. Emphasis is put on the effects of the clip stiffness and position on the critical flow velocity, equilibrium configuration and natural frequencies. It is found that variations in the retaining clip stiffness can cause different types of non-trivial equilibrium configurations. The natural frequencies will not be monotonic with the increasing clip stiffness in the supercritical flow. Furthermore, the two-span model of the pipe with the clip is obtained for verification. In conclusion, this work lays a foundation for the study of the dynamic response of the supercritical fluid-conveying pipe with retaining clip and can provide a reference for the analysis of the vibration characteristics of the clips and pipes system in engineering. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, a facile one-step solvothermal method with the assistance of hydrochloric acid has been developed to prepare well-dispersed CeO2 hollow nanospheres with high surface areas. The effects of hydrochloric acid on the growth mechanism and the size distribution are investigated in detail. It is found that the hydrogen ions expedite the nucleation rate of the CeO2 nuclei in the nucleation course, while the chloride ions accelerate the Ostwald ripening in the acidic environment. Both the hydrogen ion (H+) and the chloride ion (Cl−) are confirmed to play a key role in the formation of hollow morphology. Based on our experiments, a HCl-assisted oxidation–nucleation with an Ostwald ripening process mechanism was proposed. Furthermore, Au nanoparticles with a size of 2.5–6 nm were uniformly deposited on the surface of the ceria support by a simplified reduction process with sodium borohydride (NaBH4). The synthesized Au/CeO2 nanospheres exhibit a higher catalytic activity in CO oxidation than pure ceria nanospheres due to the existence of different Au species (metallic Au0 and positively charged Auδ+) and the strengthened interfacial interactions between the Au NPs and the ceria support. [ABSTRACT FROM AUTHOR]

A facile method of coating polystyrene (PS) particles with organo-silica and their functionalization was presented. By adding the organo-silane precursor into PS aqueous solution in presence of ammonia, an organo-silica shell could be coated on PS particles directly. This method has several characteristics. First, only one process, one precursor and one solvent were used. Second, the organic groups could be varied from methyl, propyl, vinyl, to mercaptopropyl. The third is the tunable shell thickness with a high monodispersity. The organo-silica shells are further functionalized. The PS@vinyl-SiO 2 particles were used to assemble colloidal crystals, and further modified with bromine, resulting in tunable photonic band gaps. PS@mercaptopropyl-SiO 2 particles allow the encapsulation of Au nanoparticles. The resulting 2.2 nm Au particles were stable at 550 °C and well-distributed in the whole SiO 2 shell with a loading up to 20 wt%. [ABSTRACT FROM AUTHOR]

Aluminium-doped zinc oxide (ZAO) nanocrystals with uniform size, high purity and good degree of crystallinity were prepared by an ultrasonic–microwave assisted method. The structure, optical properties and morphologies of ZAO nanocrystals were characterised by X-ray powder diffraction, ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy, while the photocatalytic and anticorrosive effects of the product were studied by the degradation test of rhodamine B and salt spray corrosive test, respectively. The effects were quite satisfactory. [ABSTRACT FROM AUTHOR]