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This paper presents a simple and fast closed-form solution approach for two-dimensional (2D) target localization using range difference (RD) measurements. The formulation of the localization problem is derived using a pentagram array. The target position is determined using passive radar measurements (RDs) between the target and the ( N + 1 = 10 ) receivers' locations. The method facilitates the problem of target position and can be used as a counter-parallel method for spherical interpolation (SI) and spherical intersection (SX) methods in time difference of arrival (TDOA) and radar systems. The performance of the method is examined in 2D target localization using numerical analysis under the distribution of receivers in the pentagram array. The simulations are conducted using four different far-distance targets and comparatively large-area distributed receivers. The RD measurements were distorted by two different values of Gaussian errors based on ionosphedriec time delays of 20 and 50 nsec owing to the different receivers' positions. The findings highly verified the validity of the method for addressing the problem of target localization. Additionally, a theoretical accuracy study of the method is given, which solely relies on the RD measurements. [ABSTRACT FROM AUTHOR]

With the growing scarcity of spectrum resources, wideband spectrum sensing is necessary to process a large volume of data at a high sampling rate. For some applications, only second-order statistics are required for spectrum estimation. In this case, a fast power spectrum sensing solution is proposed based on the generalized coprime sampling. The solution involves the inherent structure of the sensing vector to reconstruct the autocorrelation sequence of inputs from sub-Nyquist samples, which requires only parallel Fourier transform and simple multiplication operations. Thus, it takes less time than the state-of-the-art methods while maintaining the same performance, and it achieves higher performance than the existing methods within the same execution time without the need to pre-estimate the number of inputs. Furthermore, the influence of the model mismatch has only a minor impact on the estimation performance, allowing for more efficient use of the spectrum resource in a distributed swarm scenario. Simulation results demonstrate the low complexity in sampling and computation, thus making it a more practical solution for real-time and distributed wideband spectrum sensing applications. [ABSTRACT FROM AUTHOR]

Antenna arrays are used for signal processing in sonar and radar direction of arrival (DOA) estimation. The well-known array geometries used in DOA estimation are uniform linear array (ULA), uniform circular array (UCA), and rectangular grid array (RGA). In these geometries, the neighboring elements are separated by a fixed distance λ/2 (λ is the wavelength), which does not perform well for d greater than λ/2. Uniform rectangular arrays introduce grating lobes, which cause poor DOA estimation performance, especially for wideband sources. Random sampling arrays are sometimes practically not realizable. Periodic geometries require numerous sensors. Based on the minimization of the number of sensors, this paper developed a novel pentagram array to address the problem of DOA estimation of wideband sources. The array has a fixed number of elements with variable element spacing and is abbreviated as (FNEVES), which offers a new idea for array design. In this study, the geometric structure is designed and mathematically analyzed. Also, a DOA signal model is designed based on a spherical radar coordinate system to derive its steering manifold matrix. The DOA estimation performance comparison with ULA and UCA geometries under the multiple signal classification (MUSIC) algorithm using different wideband scenarios is presented. For further investigation, more simulations are realized using the minimum variance distortionless (MVDR) technique (CAPON) and the subtracting signal subspace (SSS) algorithm. Simulation results demonstrate the effectiveness of the proposed geometry compared to its counterparts. In addition, the SSS, through the simulations, provided better results than the MUSIC and CAPON methods. [ABSTRACT FROM AUTHOR]

Invasive fungal infections have increased remarkably, which have become unprecedented concern to human health. However, the effectiveness of current antifungal drugs is limited due to drug resistance and toxic side‐effects. It is urgently required to establish the effective biosynthetic strategy for developing novel and safe antifungal molecules economically. Echinocandins become a promising option as a mainstay family of antifungals, due to specifically targeting the fungal specific cell wall. To date, three kinds of echinocandins for caspofungin, anidulafungin, and micafungin, which derived from pneumocandin B0, echinocandin B, and FR901379, are commercially available in clinic and have shown potential in managing invasive fungal infections in a cost‐effective manner. However, current echinocandins‐derived precursors all are produced by environmental fungal isolates with long fermentation cycle and low yields, which challenge the production efficacy of these precursors in industry. Therefore, understanding their biosynthetic machinery is of great importance for improving antifungal titres and creating new echinocandins‐derived products. With the development of genome‐wide sequencing and establishment of gene‐editing technology, there are a growing number of reports on echinocandins‐derived products and their biosynthetic gene clusters. This review briefly summarizes the discovery and development history of echinocandins, compares their structural characteristics and biosynthetic processes, and sums up existed strategies for improving their production. Moreover, the genomic analysis of related biosynthetic gene clusters of echinocandins is discussed, highlighting the similarities and differences among the clusters. Last, the biosynthetic processes of echinocandins are compared, focusing on the activation and attachment of side‐chains and the formation of the hexapeptide core. This review aims to provide insights into the development and production of new echinocandin drugs by modifying the structure of echinocandin‐derived precursors and/or optimizing the fermentation processes; and achieve a new microbial chassis for efficient production of echinocandins in heterologous hosts. [ABSTRACT FROM AUTHOR]

We examine a simple upper bound to the gradient-based kinetic energy density (KED) of noninteracting electrons in an external potential: t (r) ≤ [ μ − v (r) ] n (r) + 1 4 ∇ 2 n (r) , where t(r) is the gradient-based (non-negative) KED, μ is the Fermi energy, v(r) is the external potential, and n(r) is the electron density. The bound emerges naturally from a well-known expression for t(r), leading to an intuitive physical interpretation. For example, t(r) approaches the upper bound in regions where the electron density consists mainly of contributions from states with energies close to the Fermi energy. This upper bound complements the orbital-free lower bound provided by the gradient form of the von Weizsäcker (vW) KED, which is also non-negative. Both bounds yield t(r) exactly for single-orbital systems, and accordingly, they merge in single-orbital regions of more general systems. We demonstrate the universality of the two bounds over a wide range of test systems, including model potentials, atoms, diatomic molecules, and pseudopotential approximations of crystals. We also show that the exact t(r) frequently exceeds the sum of the vW and Thomas-Fermi KEDs, rendering that sum unsuitable as a strict upper bound to the gradient-based KED. [ABSTRACT FROM AUTHOR]

Rationale: The 5-HT2A receptor is the major target of classic hallucinogens. Both DOI (2,5-dimethoxy-4-iodoamphetamine) and lisuride act at 5-HT2A receptors, and lisuride shares comparable affinity with DOI and acts as a partial agonist at 5-HT2A receptors. However, not like DOI, lisuride lacks hallucinogenic properties. Impulsive decision-making refers to the preference for an immediate small reinforcer (SR) over a delayed large reinforcer (LR). Objectives: The current study aims to compare the effects of DOI and lisuride on impulsive decision-making and further to investigate the possible receptor mechanisms responsible for the actions of the two drugs. Methods: Impulsive decision-making was evaluated in male Sprague–Dawley rats by the percentage of choice for the LR in delay discounting task (DDT). Delay to the LR changed in an ascending order (0, 4, 8, 16, and 32 s) across one session. Results: DOI (0.5 and 1.0 mg/kg) increased impulsive decision-making, and the effects of DOI (1.0 mg/kg) were blocked by the 5-HT2A receptor antagonist ketanserin (1.0 mg/kg) rather than the 5-HT2C receptor antagonist SB-242084 (1.0 mg/kg). Contrarily, lisuride (0.1, 0.3, and 0.5 mg/kg) decreased impulsive decision-making. The effects of lisuride (0.3 mg/kg) were not antagonized by ketanserin (1.0 mg/kg), selective 5-HT1A antagonist WAY-100635 (1.0 mg/kg), or selective dopamine D4 receptor antagonist L-745870 (1.0 mg/kg) but were attenuated by the selective dopamine D2/D3 receptor antagonist tiapride (40 mg/kg). Conclusions: DOI and lisuride have contrasting effects on impulsive decision-making via distinct receptorsDOI-induced increase of impulsivity is mediated by the 5-HT2A receptor, while lisuride-induced inhibition of impulsivity is regulated by the dopamine D2/D3 receptor. [ABSTRACT FROM AUTHOR]

We present a non-decomposable approximation for the non-additive non-interacting kinetic energy (NAKE) for covalent bonds based on the exact behavior of the von Weizsäcker (vW) functional in regions dominated by one orbital. This covalent approximation (CA) seamlessly combines the vW and the Thomas-Fermi functional with a switching function of the fragment densities constructed to satisfy exact constraints. It also makes use of ensembles and fractionally occupied spin-orbitals to yield highly accurate NAKE for stretched bonds while outperforming other standard NAKE approximations near equilibrium bond lengths. We tested the CA within Partition-Density Functional Theory (P-DFT) and demonstrated its potential to enable fast and accurate P-DFT calculations. [ABSTRACT FROM AUTHOR]

For an electronic system, given a mean field method and a distribution of orbital occupation numbers that are close to the natural occupations of the correlated system, we provide formal evidence and computational support to the hypothesis that the entropy (or more precisely −σS, where σ is a parameter and S is the entropy) of such a distribution is a good approximation to the correlation energy. Underpinning the formal evidence are mild assumptions: the correlation energy is strictly a functional of the occupation numbers, and the occupation numbers derive from an invertible distribution. Computational support centers around employing different mean field methods and occupation number distributions (Fermi–Dirac, Gaussian, and linear), for which our claims are verified for a series of pilot calculations involving bond breaking and chemical reactions. This work establishes a formal footing for those methods employing entropy as a measure of electronic correlation energy (e.g., i-DMFT [Wang and Baerends, Phys. Rev. Lett. 128, 013001 (2022)] and TAO-DFT [J.-D. Chai, J. Chem. Phys. 136, 154104 (2012)]) and sets the stage for the widespread use of entropy functionals for approximating the (static) electronic correlation. [ABSTRACT FROM AUTHOR]

Abnormallyactivated FGFR1 has been validated as a therapeutic target for differentcancers. Although a variety of FGFR inhibitors have shown benefit in manyclinical patients with FGFR1 aberration, FGFR1 mutant resistance such as V561Mmutation, has been reported. To date however, no FGFR inhibitors have beenapproved to treat patients with FGFR mutant resistance. Herein, we report that GZD824, athird generation ABL inhibitor (Phase II, China), overcomes FGFR1‐V561F/M mutant resistance in vitro and in vivo. GZD824potently suppresses FGFR1/2/3 with an IC50 value of 4.14 ± 0.96, 2.77 ± 0.082, and 8.10 ± 0.15 nmol/L. It effectively overcomes FGFR1‐V561F/M and other mutantresistance in Ba/F3 stable cells (IC50:8.1–55.0 nM), and effectively inhibits the growth of Ba/F3‐FGFR1‐V561F/M mutantxenograft tumors in vivo (TGI=73.4%, 49.8% at20mg/kg, p.o, q2d). GZD824may be considered to be an effective drug to treat patients with FGFR1 abnormalactivation or mutant resistance in clinical trials. [ABSTRACT FROM AUTHOR]

The accuracy of charge‐transfer excitation energies, solvatochromic shifts, and other environmental effects calculated via various density‐embedding techniques depend critically on the approximations employed for the nonadditive noninteracting kinetic energy functional, Tsnadn. Approximating this functional remains an important challenge in electronic‐structure theory. To assist in the development and testing of approximations for Tsnadn, we derive two virial relations for fragments in molecules. These establish separate connections between the nonadditive kinetic energies of the noninteracting and interacting systems of electrons, and quantities such as the electron‐nuclear attraction forces, the partition (or embedding) energy and potential, and the Kohn‐Sham potentials of the system and its parts. We numerically verify both relations on diatomic molecules. [ABSTRACT FROM AUTHOR]

To shorten the preparation time of porous starch while simultaneously ensuring its adsorption performance, we treated corn starch with a combination of microwave and complex enzymatic (α-amylase and amyloglucosidase) hydrolysis. Specifically, we investigated the effect of microwave and enzymatic hydrolysis on the structure, physicochemical properties, and adsorption capability of the prepared porous starch. The results showed that the porous starch prepared by combined treatment had denser pores, no new groups were produced in the porous starch, the relative crystallinity, gelatinization temperature, and solubility increased, while the gelatinization enthalpy and swelling power decreased. Compared to enzymatic hydrolysis, the combined treatment yielded starch samples with a larger specific surface area and pore capacity, and the adsorption performance was significantly improved, with water and oil absorption rates increasing from 110.99 % and 133.11 % to 128.29 % and 143.3 %, respectively. These findings indicate that the synergistic processing of microwave and enzymatic hydrolysis has great potential as a productive and rapid method for the preparation of porous starch. [Display omitted] [ABSTRACT FROM AUTHOR]

The conventional method of centralizing information fusion is commonly employed for sorting radar signals in reconnaissance receivers. However, challenges arise when the distance between reconnaissance receivers and the fusion center is distant, or when the fusion center is compromised by hostile forces. To address these issues, this paper proposes a novel distributed information fusion method. In this method, each reconnaissance receiver is restricted to accessing adjacent nodes within an undirected graph for information transmission and local computation. The distributed Dempster's combination rule and the cautious conjunctive rule are implemented using weight functions and consensus algorithms. Furthermore, an innovative outlier detection algorithm is incorporated into the fusion process to enhance its robustness. Experimental results demonstrate that the proposed method effectively improves the accuracy of radar signal sorting. When the sorting accuracy of a single reconnaissance receiver is equal to or higher than 60%, both fusion rules achieve a sorting accuracy of 100%. Even when the sorting accuracy of a single reconnaissance receiver is as low as 50%, the fused result still maintains a sorting accuracy of over 97%. [ABSTRACT FROM AUTHOR]

The authors described gold nanoclusters (AuNCs) for use on an 'on − off − on' NIR fluorescent probe for the determination of citrate and Cu(II) ion. The AuNCs were prepared by a microwave-assisted method using BSA as both the stabilizing and reducing agent. The resulting BSA-capped AuNCs display NIR fluorescence peaking at 680 nm under 500 nm excitation, a quantum yield of ~6.0%, an average size of 2.8 ± 0.5 nm, water-dispersibility, stability and biocompatibility. The on−off probe for Cu(II) is based on the interaction between Cu(II) and BSA which causes the fluorescence of the BSA−AuNCs to be quenched. The quenched fluorescence is recovered on addition of vitamin C (VC), obviously due to complexation of Cu(II) by citrate. The probe was employed to image Cu(II) and citrate in HeLa cells and in aqueous solutions. The method works in the 20 nM to 0.1 mM concentration range for Cu(II), and in the 8 nM to 120 μM concentration range for VC. [ABSTRACT FROM AUTHOR]

Temperature measurement in biology and medical diagnostics is of great importance. Herein, a novel carbon nanodot (CND) based fluorescent nanothermometry device for spatially resolved temperature measurements is demonstrated. The fluorescence CNDs are prepared by a simple one-pot solvothermal method using sucrose as carbon source. Resultant CNDs show stable green fluorescence at 520 nm with high quantum yield (≈6%). The fluorescence of resultant CNDs exhibits a reversible linear response to temperature in a wide range of 20-85 °C. Moreover, the temperature resolution better than 0.5 °C and high sensitive variation of ≈1.3% °C−1 are observed in a broad physiological temperature range of 20-40 °C. Therefore, the as-prepared CNDs possess high water solubility, stable fluorescence, small size, and good biocompatibility, which make them promising candidate for thermometry and cell imaging in biological media. [ABSTRACT FROM AUTHOR]

Temperature measurements in biology and medical diagnostics, along with sensitive temperature probing of living cells, is of great importance; however, it still faces significant challenges. Herein, a novel 'turn-on' carbon-dot-based fluorescent nanothermometry device for spatially resolved temperature measurements in living cells is presented. The carbon nanodots (CNDs) are prepared by a green microwave-assisted method and exhibit red fluorescence ( λem=615 nm) with high quantum yields (15 %). Then, an on-off fluorescent probe is prepared for detecting glutathione (GSH) based on aggregation-induced fluorescence quenching. Interestingly, the quenched fluorescence could be recovered by increasing temperature and the CNDs-GSH mixture could behave as an off-on fluorescent probe for temperature. Thus, red-emitting CNDs can be utilized for 'turn-on' fluorescent nanothermometry through the fluorescence quenching and recovery processes, respectively. We employ MC3T3-E1 cells as an example model to demonstrate the red-emitting CNDs can function as 'non-contact' tools for the accurate measurement of temperature and its gradient inside a living cell. [ABSTRACT FROM AUTHOR]

Approximations of the non-additive non-interacting kinetic energy (NAKE) as an explicit functional of the density are the basis of several electronic structure methods that provide improved computational efficiency over standard Kohn-Sham calculations. However, within most fragment-based formalisms, there is no unique exact NAKE, making it difficult to develop general, robust approximations for it. When adjustments are made to the embedding formalisms to guarantee uniqueness, approximate functionals may be more meaningfully compared to the exact unique NAKE. We use numerically accurate inversions to study the exact NAKE of several rare-gas dimers within partition density functional theory, a method that provides the uniqueness for the exact NAKE. We find that the NAKE decreases nearly exponentially with atomic separation for the rare-gas dimers. We compute the logarithmic derivative of the NAKE with respect to the bond length for our numerically accurate inversions as well as for several approximate NAKE functionals. We show that standard approximate NAKE functionals do not reproduce the correct behavior for this logarithmic derivative and propose two new NAKE functionals that do. The first of these is based on a re-parametrization of a conjoint Perdew-Burke-Ernzerhof (PBE) functional. The second is a simple, physically motivated non-decomposable NAKE functional that matches the asymptotic decay constant without fitting. [ABSTRACT FROM AUTHOR]

Abstract: A novel and simple growth mark method was developed to make marks during the growth process of carbon nanotube arrays. These marks can be read out under scanning electron microscope or optical microscope. Based on this method, the growth rates at different temperatures and under different acetylene partial pressures were measured, from which the activation energy and the order of reaction were determined. Based on our experimental results, the growth of carbon nanotube arrays in our experimental condition could not be diffusion-limited. The measured activation energy could possibly be attributed to the heterogeneous decomposition of acetylene over the catalyst particle. Furthermore the marked array with special segmental structure may be found some applications in the future. [Copyright &y& Elsevier]

An effective field emitter has been developed by modifying an individual multiwalled carbon nanotube (MWCNT) tip with LaB6. The modified emitter possesses the merits of both the MWCNT and LaB6, which presents a significant low turn-on voltage, good emission properties, and long lifetime. As a result, a total current of 70 μA has been reached at a very low electric field of only 1.2 V/μm for an individual modified MWCNT emitter, which is also expected to have advantages of high brightness and coherence, clearly indicating great promise for practical applications such as electron guns or cathodes for field emission flat panel display. [ABSTRACT FROM AUTHOR]

Polarized light emission from multiwalled carbon nanotube (MWNT) bundles due to current heating is observed. The spectra of the emitted light fit well with the blackbody radiation distribution. And the emitted light is partially polarized with a degree of 0.33 along the axis of MWNT bundle, which is qualitatively explained in terms of one-dimensional structure of carbon nanotubes (CNTs). Negative temperature-dependent resistance is also observed, which is different from normal metal filaments. The MWNT bundles are very stable at high temperature in vacuum during light emitting, indicating that CNTs can be a good candidate as polarized incandescent light sources. [ABSTRACT FROM AUTHOR]

In recent years, there has been significant progress in the synthesis of one-dimensional and two-dimensional materials. Thus, a new challenge has arisen in efficiently characterizing the homogeneity of the as-grown samples. To meet such a demand, several methods have been developed to evaluate the homogeneity of carbon nanotubes (CNTs) and graphene, including direct optical visualization of ultralong CNTs via vapor-condensation-assisted optical microscopy; true-color real-time Rayleigh imaging of CNTs that helps to assign chiral indices; scanning electron microscopy imaging of CNTs via the contrast provided by their conductivity and bandgap; and low-energy transmission electron diffraction and imaging of large-area graphene to identify the crystal orientations. These methods all show the advantages of high-throughput and high-efficiency. This review briefly summarizes the recent works and discussed their characteristics. It is believed that these methods are not limited to CNTs and graphene; they can also be applicable to an extensive range of nanomaterials. [ABSTRACT FROM AUTHOR]

Temperature measurement in biology and medical diagnostics, along with sensitive temperature probing in living cells, is of great importance. Here, a novel “turn‐on” carbon‐dot‐based nanothermometry device for spatially resolved temperature measurements in living cells is demonstrated. The red fluorescence of carbon nanodots could be quenched by glutathione and recovered by increasing temperature. Thus, fluorescent nanothermometry is achieved through the fluorescence quenching and recovery processes, respectively. More information can be found in the Communication by C. Wang, C. Zhang et al. on page 14475 ff. [ABSTRACT FROM AUTHOR]

The carbon nanotube (CNT) is a compelling and promising material for industrial applications requiring high strength and rigidity. For a multi-walled CNT (MWCNT), the nominal tensile strength and Young's modulus (considering the whole cross-sectional area of the specimen) are key mechanical factors for the practical application of macroscopic fibers and composites. However, the nominal tensile strength and Young's modulus of MWCNTs are much lower than their effective tensile strength and Young's modulus (considering the fracture cross-sectional area) because the outermost graphite layer always fractures first due to the low cross-link between graphite layers. In this paper, we fabricated the carbon nanofibers (CNFs) by epitaxial growth on super-aligned MWCNT film template and conducted in situ uniaxial tensile tests on individual carbon-nanotube-templated CNFs. The individual CNFs show improved nominal mechanical performance than previously reported MWCNTs. The nominal mechanical properties enhancement of the CNFs is attributed to the effective control on load transfer between interwalls. [ABSTRACT FROM AUTHOR]

Transition metal chalcogenides, especially molybdenum disulfide, have recently got wide attention from researchers because of their unique intrinsic characteristics. However, until now, few literatures have reported the photoluminescent MoS 2 materials and their applications. In this work, we reported a bottom-up strategy to synthesize water-soluble molybdenum disulfide quantum dots (MoS 2 QDs) through a facile hydrothermal route using sodium molybdate and glutathione as Mo and S sources. The obtained MoS 2 QDs show blue emission with a high quantum yield (∼10.3%) and robust dispersibility and storage stability optical property in aqueous solution. During the experiment, we found that in the presence of hydrogen peroxide (H 2 O 2) , the fluorescence of MoS 2 QDs is quenched due to the interaction between H 2 O 2 and MoS 2 QDs. Simultaneously, glucose oxidase catalyzes the oxidation of glucose to produce gluconic acid and H 2 O 2 , so we can use this probe to detect glucose. By reason of the high zymolyte specificity of glucose oxidase, the detection of glucose has good selectivity and sensitivity with a detection limit of 5.16 μM. Finally, the method is successfully applied for detection of glucose in fetal bovine serum samples. [ABSTRACT FROM AUTHOR]

The preparation and applications of fluorescent Ag nanoclusters (AgNCs) have been developed rapidly. However, the poor stability and time-consuming in synthesis process limit their further application. Herein, a rapid sonochemical route is used to synthesize fluorescent AgNCs using hydrazine hydrate as reducing agent and glutathione (GSH) as capping agent. The AgNCs would be formed quickly (∼15 min) due to presence of ultrasonic wave, which show red fluorescence (λ em = 645 nm), small size (∼2 nm) and good dispersion in aqueous solution. Moreover, GSH, as protecting agent on the surface of resultant AgNCs, has many functional groups including carboxyl and amino groups which make NCs show high photo-, time-, metal- and pH-stability. Then a stable Ag nanoclusters-based nano-sensor is designed for highly sensitive and selective label-free detection of Pb 2+ . This nanosensor shows a potential application as probe for monitoring Pb 2+ not only in aqueous solution but also in living cells. Thus, these stable and fluorescent AgNCs could work as an alternative to conventional fluorescence probes for biolabeling, sensing and other applications. [ABSTRACT FROM AUTHOR]

A novel dual-emitting fluorescence probe is developed for rapid and ultrasensitive detection of Fe3+. The nanoprobe is prepared by coating CdSe semiconductor quantum dots (SQDs) onto the surface of carbon nanodot (CND) doped TiO2 microspheres. The as-prepared nanoprobe exhibits the corresponding dual emissions at 436 and 596 nm for CNDs and CdSe, respectively, under a single excitation wavelength. The blue fluorescence of the CNDs is insensitive to Fe3+, whereas the orange emission of the CdSe SQDs is functionalized to be selectively quenched by Fe3+. The intensity ratio of I436/I596 shows a good linear relationship with the concentration of Fe3+ in the range of 10−9 to 10−5 M. The nanoprobe provides an effective platform for the reliable detection of Fe3+ with a detection limit as low as 10 nM. Besides, this ratiometric nanosensor exhibits good selectivity for Fe3+ over other metal ions. The results reveal that the nanoprobe could provide a sensitive sensor for rapid detection of Fe3+ with high selectivity and sensitivity. Moreover, 293T cells are used as models to achieve a potential application as a probe for monitoring Fe3+ in cells. Thus, these dual-emitting nanoprobes could work as an alternative to conventional fluorescence probes for biolabeling, sensing and other applications. [ABSTRACT FROM AUTHOR]

The creation of continuous yarns made out of carbon nanotubes would enable macroscopic nanotube devices and structures to be constructed. Here we show that carbon nanotubes can be self-assembled into yarns of up to 30 cm in length simply by being drawn out from superaligned arrays of carbon nanotubes, and that the strength and conductivity of these yarns can be enhanced by heating them at high temperatures. Our findings should help to translate the remarkable mechanical, electrical and thermal properties of carbon nanotubes to a macroscopic scale. [ABSTRACT FROM AUTHOR]

Amphibious carbon dots (CDs) are prepared by a rapid microwave method; they emit strong yellow emission in H2O, CHCl3, and a polymer matrix. The CDs can be used as a colorimetric nanosensor for the discrimination of Cr(III) and Cr(VI) [ABSTRACT FROM AUTHOR]

Au nanoparticles with diameters about 1.4 nm were dispersed onto porous Si 3 N 4 grids and applied for growing single-walled carbon nanotubes (SWCNTs) by chemical vapor deposition. Particularly, SWCNTs with diameters in the range of 0.75–1.8 nm were produced at a reaction temperature of 700 °C using CO as the carbon precursor. Nanobeam electron diffraction characterizations revealed that most of the SWCNTs have large chiral angles and zigzag SWCNTs were hardly detected. Density functional theory calculations showed that the SWCNT-Au interface formation energy and the SWCNT growth kinetics account for the enrichment of large chiral angle SWCNTs in the product. To correlate single-walled carbon nanotube chirality with the element of Au, thermal chemical vapor deposition growth is performed on uniform Au nanoparticles at 700 °C using CO as the carbon precursor. The nanotube chirality distribution is determined by electron diffraction technique, which reveals a bias to large chrial angle species, a result of low tube-Au interface formation energy and high stability of the extruded edge hexagons. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Porous Li4Ti5O12 nanoclusters with high surface area are synthesized by a facile solution-based method followed by low-temperature calcination. The Li4Ti5O12 nanoclusters present the key characteristics needed to serve as high-performance negative electrodes for lithium ion batteries, including nano-sized dimension of the Li4Ti5O12 clusters (50–100 nm) for short ion and electron transfer path, and high surface area (142 m2 g−1) with mesoporosity (pore diameter 2–6 nm) for easy access to the electrolyte and efficient ion transport. Based on these characteristics, the Li4Ti5O12 electrode delivers an initial capacity of 173 mAh g−1 at the rate of 0.5 C, comparable to its theoretical capacity. Excellent cycling stability at high rates is achieved in the Li4Ti5O12 electrode, offering potential to serve as a negative electrode material for high rate lithium ion battery applications. [Copyright &y& Elsevier]

Suspending superaligned multiwalled carbon nanotube (MWCNT)filmswere processed into CNT thin yarns, about 1 μm in diameter,by laser cutting and an ethanol atomization bath treatment. The fasthigh-temperature response under a vacuum was revealed by monitoringthe incandescent light with a photo diode. The thin yarns can be electricallyheated up to 2170 K in 0.79 mS, and the succeeding cool-down timeis 0.36 mS. The fast response is attributed to the ultrasmall massof the independent single yarn, large radiation coefficient, and improvedthermal conductance through the two cool ends. The millisecond responsetime makes it possible to use the visible hot thin yarns as light-emittingelements of an incandescent display. A fully sealed display with 16× 16 matrix was successfully fabricated using screen-printedthick electrodes and CNT thin yarns. It can display rolling characterswith a low power consumption. More applications can be further developedbased on the addressable CNT thermal arrays. [ABSTRACT FROM AUTHOR]

Abstract: A newly developed vacuum sensor using carbon nanotube (CNT) field-emission has been designed. The fabricated device is an ionization gauge with a silk-like CNT yarn cathode, and the vacuum is indicated by the ratio of the ion current to the electron-emission current. The metrological characteristics of the sensor were studied in a dynamic vacuum system. It showed good linearity ranged from 10−4 to 10−1 Pa. Taking advantage of the field-emission cathode, the power consumption is only about 5.5 mW. Moreover, comparing it to the conventional thermionic cathode, the CNT yarn cathode is more miniature and a cold cathode with no obvious thermal outgassing effect. Due to these features, the sensor described here could have potential applications in measuring vacuum inside sealed and miniaturized devices. [Copyright &y& Elsevier]

Abstract: Super-aligned carbon nanotube (CNT) film is a transparent conductive film composed of numerous parallel CNTs connected to each other by the van der Waals force. We have found that such films, attached to glass, can readily align liquid crystal molecules. A prototype liquid crystal display (LCD) using the film as the aligning layer has been fabricated. The on–off ratio of the as-prepared display cell is 85 when 24V is the applied voltage. Because of its high transparency, the film can simultaneously be used as a transparent electrode material, in place of expensive indium tin oxide. The resistance of the film makes it a suitable built-in heating layer, extending the working temperature range of LCDs. [Copyright &y& Elsevier]

Abstract: Y-junctions and related carbon nanotube (CNT) junctions were synthesized by Au-catalyzed chemical vapor deposition. The catalyst was prepared by evaporating a 10-nm-thick Al2O3 film and a 1-nm-thick Au film on a Si substrate. Based on thorough investigations under a high-resolution transmission electron microscope, the CNT junctions were proved to be formed by a unified catalyst-merging mechanism. Different merging processes resulted in different morphologies, such as Y-shaped, T-shaped, multi-leveled, multi-terminal and L-shaped CNT junctions. [Copyright &y& Elsevier]

Abstract: The effect of carbon deposits on the reactor wall during the growth of multi-walled carbon nanotube (MWCNT) arrays was studied. It was found that the carbon deposits were helpful in converting the continuous catalyst film into carbon-containing nanoparticles before growth started, which was beneficial for the nucleation of MWCNT arrays. As a result, MWCNT arrays synthesized in a reactor with carbon deposits were well aligned with high nucleation density. Further study revealed that this effect could be probably ascribed to some activated species adsorbed in the carbon deposits. These results will be helpful in the repeatable synthesis of high quality MWCNT arrays and in understanding the nucleation process of MWCNT arrays. [Copyright &y& Elsevier]

The perception of jamming types is very important for protecting our radar in complex electromagnetic environments. Radar active deceptive jamming based on digital radio frequency memory (DRFM) has a high coherence with the target echo, which confuses the information of the target echo and achieves the effect of hiding the real target. Traditional deceptive jamming recognition methods need to extract complex features and artificially set classification thresholds, which is inefficient. The existing neural network-based jamming identification methods still follow the pattern of signal modulation-type identification, so there are fewer types of jamming that can be identified, and the identification accuracy is low in the case of low jamming-to-noise ratios (JNR). This paper studies the input of jamming recognition networks and proposes an improved intelligent identification method for chirp radar deceptive jamming. This method fuses three short-time Fourier transform time–frequency graphs disturbed by three consecutive pulse periods into a new graph as the input of the convolutional neural network (CNN). Using a CNN to classify the time–frequency image has realized the recognition of a variety of common deceptive jamming techniques. Similarly, by changing the network input, the original signal is used to replace the echo signal, which improves the accuracy of the jamming recognition in the case of a low JNR. [ABSTRACT FROM AUTHOR]

We report the design and simple spray coating fabrication process of a perfect absorber based on carbon nanotubes (CNTs) and carbon black particles with omnidirectional high absorption efficiency beyond 99.9% over the broad wavelength range from 400 nm to 20 μm. The carbon black particles are introduced into the CNT solution to form multi-scale all-carbon-based nanomaterials, effectively modifying the morphology of the sprayed layer to improve the light absorption. The promising absorption characteristics of the CNT–carbon black layer are attributed to not only the intrinsic optical properties of the carbon nanomaterials but also the unique surface nanostructures that efficiently trap light. In addition to serving as absorbers in the coating layer, the CNTs, more importantly, act as connectors between carbon black particles for absorber preparation at a large scale, which is the key to modifying the surface morphology. The all-carbon-based coating layer is also shown to be effective for solar thermal harvesting and self-cleaning function. The developed mixing method for CNTs and carbon black particles in solutions opens a new path for the realization of multi-functional sprayed layers based on CNTs and advances the technology of CNT coatings for scale-up to industry applications. [Display omitted] [ABSTRACT FROM AUTHOR]

By using superaligned carbon nanotube (SACNT) macrostructures as reinforcements, the one-step homoepitaxial growth of SACNT/graphite composites was achieved with a home-built experimental setup at temperatures as high as 2600 °C. Compared with traditional furnace heating method, this approach offers the advantages of increased convenience, high throughput and energy efficiency. This high-temperature homoepitaxy strategy was applied to three kinds of structures: SACNT yarn, SACNT film, and SACNT array. Because of the high temperature which exceeded 1800 °C, the samples after high-temperature homoepitaxy showed increased G/D peak area ratios in the Raman spectra, enhanced mechanical properties and improved thermal properties, all of which can meet the requirements of various applications. Image 1 • Three kinds of superaligned carbon nanotube (SACNT) structures are used for macroscopic continuity and manipulation. • The SACNT/graphite composite has been fabricated in a home-built experimental setup by self-heating up to 2600℃. • One-step fulfilment of both carbon deposition and simultaneous graphitization leads to convenience and energy efficiency. • Samples after high-temperature homoepitaxy exhibit increased G/D ratio in Raman spectra and superior material performance. [ABSTRACT FROM AUTHOR]

Three dimensional TiO 2 –Au cross-nanoporous structure (3D TiO 2 –Au CNS) as an efficient photoelectrocatalytic system was fabricated using superaligned carbon nanotube films as etching masks and electron-beam evaporation. The 3D TiO 2 –Au CNS exhibited a broad absorption band in the visible region, and the incident photon-to-current conversion efficiency of 3D TiO 2 –Au CNS/Ti electrode was 3–4 times higher than that of pure TiO 2 electrode. The photocurrent density of the 3D TiO 2 –Au CNS device was 0.079 mA cm−2 at 0 V vs. Ag/AgCl with a solar irradiance of 100 mW cm−2. This developed preparation method was simple, of high flexibility and can be adopted for mass production due to its low cost and good compatibility with other processing technologies. The 3D TiO 2 –Au CNS and its preparation method have important value in design of photoelectrocatalytic system for research and practical applications, which may have a potential utility in photocatalytic and other photoelectrocatalytic reactions. Image 1 • 3D TiO 2 –Au CNS was fabricated by SCNT films as masks and electro-beam evaporation. • The photocatalytic performance of thin-layer TiO2 is improved in this structure. • Porous Ti substrate and Au NPs can accelerate the charge separation and transfer. • The photocurrent density of the structure was 0.079 mA cm−2 at 0 V vs. Ag/AgCl. • The preparation method is simple, flexible and can be used for mass production. [ABSTRACT FROM AUTHOR]

The transport property of six types of individual carbon nanotubes (CNT) with specified chiral indices at high temperature is investigated on a home‐made apparatus. It is found that the resistivity of all individual CNTs increases with temperature monotonically, whereas the mobility decreases with temperature and follows different laws in different temperature ranges. The carrier concentration increases exponentially with −1/T. The mobility of CNT deviates from traditional trends with temperature, T−β, at high temperature (1070–1728 K). This deviation is attributed to scattering with optical phonons at high temperature. The data show that the electron‐optical phonon interaction becomes dominant in the temperature range of 1070–1362 K for all measured CNTs. Finally, result within a polaron model is discussed. [ABSTRACT FROM AUTHOR]

High‐temperature thermionic electron emission from different types of individual suspended carbon nanotubes (CNTs) in a homemade chip is studied. When collecting emission electrons with an external electrode, it is found that the collecting electric field influence the transport current in the CNTs, and the thermionic electron emission deviated from the traditional thermionic electron emission model and cannot reach "saturation". This effect is analyzed for single‐walled, double‐walled, multiwalled‐CNT and CNT bundles. It is found that this effect show correlation with the conductivity and diameter of the CNT. With the increase in metallicity, the influence of collecting electrode is gradually weakened. Also, the effect shows a negative correlation with the diameter of CNTs. An equation is proposed to describe the measured thermionic emission curve and determine the "effective" work function of the CNT. [ABSTRACT FROM AUTHOR]

Electrical breakdown induced by Joule heating was employed to make a well-aligned surface structure from single-walled carbon nanotube (SWCNT) bundles. The surfaces at the breaking ends are tip abundant and composed of SWCNTs of high quality. In addition, the radial breathing mode frequencies of the CNT tips have a downshift than the as-grown SWCNTs, due to the higher thermal stability of wider SWCNTs and the strong intertube interactions. The ends can provide emission currents of about 100 μA, and a pixel based on these potential electron emitters was developed for lateral field emission displays. [ABSTRACT FROM AUTHOR]

We report the design and simple fabrication process of a perfect absorber based on carbon nanotube films, which enable omnidirectional high absorption efficiency over the wavelength range from 250 nm to 20 μm with polarization independence. The absorber is fabricated using layers of super-aligned carbon nanotube (SACNT) films assembled in a unique manner, which could be easily prepared on stretchable or rigid substrates or suspended. The promising absorption characteristics of the SACNT films were attributed to not only the intrinsic optical properties of the carbon nanomaterials but also the unique surface nanostructures that efficiently trapped light. Moreover, the absorber and its fabrication method exhibit excellent compatibility with various composed materials and treatment processes. Through combination with ultraviolet-curable resist, a robust, ultrathin, and ultralight absorber with good mechanical properties was fabricated on stretchable substrates. The developed fabrication method opens a new path to realize high absorption performance using carbon nanomaterials and the obtained absorber has broad prospects in aerospace and military applications. Image 1 [ABSTRACT FROM AUTHOR]

The thermoacoustic response of carbon nanotube (CNT) thin films at frequencies ranging from 300 Hz up to 100 kHz has been studied in a variety of gaseous mediums. Theoretical derivations show that the sound pressure generated by CNT thin films is approximately proportional to the inverse of the heat capacity of the gas within the audible frequency range of human hearing, which is consistent with the experimental results in argon, air, and helium. For large size CNT films, a decrease in sound pressure is observed within a higher frequency range in air, which is attributed to the destructive interference of sound waves in the near field zone according to the theoretical calculations. [ABSTRACT FROM AUTHOR]

Abstract Polyimide (PI) is a high-performance polymer with ultrahigh heat stability while carbon nanotube (CNT) possesses high mechanical strength, excellent electrical and thermal conductivity. Here we report a facile and low-cost method free from CNT pre-dispersion for fabricating super-aligned carbon nanotube (SACNT)/PI composite film which combines the advantages of both SACNT and PI. Flexible and scratch-resistant composite film with high CNT content, uniform dispersion of CNTs, and controlled patterned CNT structures can be fabricated easily via in situ imidization. The SACNT/PI composite film exhibits improvement in mechanical strength, Young's modulus, electrical conductivity compared with pristine PI, and shows good thermal stability. Thanks to these superb properties, a flexible, stable, addressable, electromagnetic wave permeable, and high-temperature fast-response multifunctional heater as well as a thermo-mechanical actuator based on SACNT/PI composite film have been demonstrated in this paper. And it also shows great potential in a variety of applications such as flexible/wearable electronics, RFID, other thermo-related devices and so on. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract Ultrathin and cross-stacked carbon nanotube (CNT) films modified with hafnium oxide (HfO 2) by atomic layer deposition are employed as efficient polysulfide barriers for high performance Li-S batteries. A HfO 2 /CNT interlayer has an ultrathin, flexible structure with a thickness of 1.5 μm and an areal density of 0.087 mg cm−2, along with excellent wettability to electrolyte. The highly conductive CNT network and the catalytic surface adsorption of polysulfide species by HfO 2 significantly suppress the polysulfides shuttling phenomenon. With high sulfur loadings of up to 75 wt%, electrodes incorporating a HfO 2 /CNT interlayer show noticeable improvements in various electrochemical properties, including long-term cycling stability (721 mA h g−1 after 500 cycles at 1 C), high rate performance (800 mA h g−1 at 5 C), favorable anti-self-discharge capabilities, and suppression of Li anode corrosion. These results suggest a new and efficient polysulfide trapping material and a viable configuration for high-performance Li-S batteries. Graphical abstract An ultrathin HfO 2 /CNT interlayer is used as an efficient polysulfide barrier to improve the performance of Li-S batteries. Image 1 [ABSTRACT FROM AUTHOR]

Abstract Developing hybrid supercapacitor-battery energy storage devices for applications in electric vehicles is attractive because of their high energy density and short charge/discharge time. In this study, flexible MnO 2 nanoparticle-coated air-oxidized carbon nanotube (MnO 2 /aCNT) electrodes are fabricated by the in situ redox reaction of KMnO 4 and aCNTs at room temperature. The MnO 2 nanoparticles have diameters of ∼10 nm. There is a strong chemical interaction between the MnO 2 active material and aCNTs as a result of the Mn–O–C linkage. The flexible aCNT network can alleviate the strain from the MnO 2 volume change and maintain the electrode integrity during rapid charge/discharge. The aCNT framework also provides a continuous and rapid electron pathway and ensures uniform dispersion of the MnO 2 nanoparticles. The presence of MnO 2 nanoparticles provides short pathways for Li-ion diffusion and allows interfacial capacitive lithium storage for ultrafast and reversible lithium storage. We report the best high-current performance to date for MnO 2 /C electrodes, of 395.8 mA h g−1 at 10 A g−1, and 630.2 mA h g−1 after 150 cycles at 2 A g−1. The excellent electrochemical performance, combined with the capacitive dominating process of the electrode, will further the design of high-performance hybrid supercapacitor-battery energy storage devices. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Vertically aligned carbon nanotube array/SiC composites (VACNT/SiCs), fabricated through chemical vapor infiltration (CVI) of SiC ceramics into the CNT arrays, have unique porous microstructures and microscopic properties along with internal CVI SiC gradient from surface to inside. The internal nanoindentation properties including modulus and hardness were characterized to be related to the CVI depths in horizontal and vertical directions, as compared to the external surface nanoindentation properties in the longitudinal and transverse directions. Results showed that the modulus and hardness of the VACNT/SiCs from surface to inside decreased linearly with the CVI depths. Besides, the fitting slopes of modulus with different CVI depths in the vertical and horizontal directions were nearly equal, but the fitting slope of hardness in the vertical direction was almost twice that in horizontal direction. Therefore, it can be indicated that the CVI deposited SiC gradient gives rise to reduction in both modulus and hardness, and has a larger effect on the latter which is mainly upon the deposited SiC quantity and density. Comparatively, the modulus along the external surface in the longitudinal was twice that in the transverse directions, 31.2 and 16.8 GPa, respectively. And the hardness in the longitudinal and transverse directions was nearly the same, 0.627 and 0.597 GPa. It can be inferred that the modulus of the VACNT/SiCs along the external surfaces shows anisotropy due to the CNT modulus anisotropy. Nevertheless, the hardness along the external surfaces was the nearly same, resulting from equally deposited SiC coating on all over the surfaces of composites. [ABSTRACT FROM AUTHOR]

Ultrathin and lightweight MoS 2 /carbon nanotube (CNT) interlayers are developed to effectively trap polysulfides in high-performance lithium–sulfur (Li–S) batteries. The MoS 2 /CNT interlayer is constructed by loading MoS 2 nanosheets onto a cross-stacked CNT film. The CNT film with excellent conductivity and superior mechanical properties provides the Li–S batteries with a uniform conductive network, a supporting skeleton for the MoS 2 nanosheets, as well as a physical barrier for the polysulfides. Moreover, chemical interactions and bonding between the MoS 2 nanosheets and the polysulfides are evident. The electrode with the MoS 2 /CNT interlayer delivers an attractive specific capacity of 784 mA h g −1  at a high capacity rate of 10 C. In addition, the electrode demonstrates a high initial capacity of 1237 mA h g −1 and a capacity fade as low as −0.061% per cycle over 500 charge/discharge cycles at 0.2 C. The problem of self-discharge can also be suppressed with the introduction of the MoS 2 /CNT interlayer. The simple fabrication procedure, which is suitable for commercialization, and the outstanding electrochemical performance of the cells with the MoS 2 /CNT interlayer demonstrate a great potential for the development of high-performance Li–S batteries. [ABSTRACT FROM AUTHOR]

The fabrication of high-performance cathodes with high sulfur content is essential for the practical realization of lithium–sulfur (Li–S) systems. The preparation of high-sulfur-content electrodes is currently hindered by poor dispersion of the conductive agents; nonuniformly distributed conductive agents cannot provide sufficient sulfur-loading sites, thereby resulting in aggregation of sulfur/Li 2 S and severe polarization. To deal with this issue, we prepare CO 2 modified carbon nanotube (CNT)-based cathodes for Li–S batteries. CNTs are exposed to CO 2 at 900 °C, resulting in uniformly distributed negative charges on the external surface of the tubes; the electrostatic repulsion facilitated the dispersion of CNTs. Compared with the previous work on CNTs prepared by air oxidation (denoted as air-CNTs), the dispersions of the CO 2 -treated CNTs (denoted as CO 2 -CNTs) are more stable, which allows higher sulfur loading and improves sulfur utilization. A free-standing CO 2 -CNT&S electrode with a sulfur content of 80 wt% is fabricated through a sonication-assisted method. The excellent dispersion of the CO 2 -CNT&S network results in little kinetic barriers, low polarization, and fast charge transport at the interface of the electrode and electrolyte. The CO 2 -CNT&S electrode delivers a lower capacity fading rate and superior rate performance compared with the air-CNT&S electrode. [ABSTRACT FROM AUTHOR]

Abstract: Endured, low‐cost, and high‐performance flexible perovskite solar cells (PSCs) featuring lightweight and mechanical flexibility have attracted tremendous attention for portable power source applications. However, flexible PSCs typically use expensive and fragile indium–tin oxide as transparent anode and high‐vacuum processed noble metal as cathode, resulting in dramatic performance degradation after continuous bending or thermal stress. Here, all‐carbon‐electrode‐based flexible PSCs are fabricated employing graphene as transparent anode and carbon nanotubes as cathode. All‐carbon‐electrode‐based flexible devices with and without spiro‐OMeTAD (2,2′,7,7′‐tetrakis‐(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene) hole conductor achieve power conversion efficiencies (PCEs) of 11.9% and 8.4%, respectively. The flexible carbon‐electrode‐based solar cells demonstrate superior robustness against mechanical deformation in comparison with their counterparts fabricated on flexible indium–tin oxide substrates. Moreover, all carbon‐electrode‐based flexible PSCs also show significantly enhanced stability compared to the flexible devices with gold and silver cathodes under continuous light soaking or 60 °C thermal stress in air, retaining over 90% of their original PCEs after 1000 h. The promising durability and stability highlight that flexible PSCs are fully compatible with carbon materials and pave the way toward the realization of rollable and low‐cost flexible perovskite photovoltaic devices. [ABSTRACT FROM AUTHOR]