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Powder metallurgy is important in material preparation. Due to the inertness of carbon materials, however, sintering powdered carbon into physically coherent bulks has been a great challenge even at a high temperature (2000 °C). Improving the sintering activity of carbon powders is the key to the success of the consolidation of the carbon powders. Here ordered mesoporous carbon (OMC) is used as the starting material to produce highly homogeneous novel carbon bulks. During sintering at 1800 °C, the huge specific surface area of the OMC greatly promotes the migration of carbon atoms and thus the sintering of the OMC by surface diffusion mechanism. When nanodiamond (ND) is added, the volume expansion associated with the phase transformation of diamond to graphite facilitates the densification of the powder compacts. The strong connection between the OMC and the graphite onions derived from the ND bestows the as-prepared carbon bulks with excellent mechanical properties. The current research pioneers a novel way to prepare high-strength carbon materials at relatively low temperatures.

Optimized Y2O3-YAG:Ce composite phosphor ceramics with designed microstructures were prepared and well suited for solid-state laser lighting with high power and brightness.

Soft robotics locomotion at the liquid-air interface has become more and more important for an intelligent society. However, existing locomotion of soft robotics is limited to two dimensions. It remains a formidable challenge to realize three-dimensional locomotion (

The histone chaperone facilitates chromatin transactions (FACT) functions in various DNA transactions. How FACT performs these multiple functions remains largely unknown. Here, we found, for the first time, that the N-terminal domain of its Spt16 subunit interacts with the Set3 histone deacetylase complex (Set3C) and that FACT and Set3C function in the same pathway to regulate gene expression in some settings. We observed that Spt16-G132D mutant proteins show defects in binding to Set3C but not other reported FACT interactors. At the permissive temperature, induction of the GAL1 and GAL10 genes is reduced in both spt16-G132D and set3Δ cells, whereas transient upregulation of GAL10 noncoding RNA (ncRNA), which is transcribed from the 3′ end of the GAL10 gene, is elevated. Mutations that inhibit GAL10 ncRNA transcription reverse the GAL1 and GAL10 induction defects in spt16-G132D and set3Δ mutant cells. Mechanistically, set3Δ and FACT (spt16-G132D) mutants show reduced histone acetylation and increased nucleosome occupancy at the GAL1 promoter under inducing conditions and inhibition of GAL10 ncRNA transcription also partially reverses these chromatin changes. These results indicate that FACT interacts with Set3C, which in turn prevents uncontrolled GAL10 ncRNA expression and fine-tunes the expression of GAL genes upon a change in carbon source.

In this study, large-scale Te-doped polycrystalline SnSe nanopowders were synthesized by a facile hydrothermal approach and the effect of Te doping on the thermoelectric properties of SnSe was fully investigated. It is found that the carrier concentration increases due to the reduction of band gap by alloying with Te, which contributes to significant enhancement of electrical conductivity especially at room temperature. Combined with the moderated Seebeck coefficient, a high power factor of 4.59 μW cm−1 K−2 is obtained at 773 K. Furthermore, the lattice thermal conductivity is greatly reduced upon Te substitution owing to the atomic point defect scattering. Benefiting from the synergistically optimized both electrical- and thermal-transport properties by Te-doping, thermoelectric performance of polycrystalline SnSe is enhanced in the whole temperature range with a maximum ZT of ∼0.79 at a relatively low temperature (773 K) for SnSe0.85Te0.15. This study provides a low-cost and simple low-temperature method to mass production of SnSe with high thermoelectric performance for practical applications

N-type Se&Lu-codoped Bi2Te3nanopowders were prepared by hydrothermal method and sintered by spark plasma sintering technology to form dense samples. By further doping Se element into Lu-doped Bi2Te3samples, the thickness of the nanosheets has the tendency to become thinner. The electrical conductivity of Lu0.1Bi1.9Te3−xSexmaterial is reduced with the increasing Se content due to the reduced carrier concentration, while the Seeback coefficient values are enhanced. The lattice thermal conductivity of the Lu0.1Bi1.9Te3−xSexis greatly reduced due to the introduced point defects and atomic mass fluctuation. Finally, the Lu0.1Bi1.9Te2.7Se0.3sample obtained a maximumZTvalue of 0.85 at 420 K. This study provides a low-cost and simple low-temperature method to mass production of Se&Lu-codoped Bi2Te3with high thermoelectric performance for practical applications.

Nanostructure is effective to improve thermoelectric performance by reducing the thermal conductivity. However, electrical conductivity is always synchronously deteriorated due to the scattering of charge carriers. Here, we introduce SiC nanoparticles into the matrix of Pb0.98Na0.02Te doped with SrTe. The two-phased heterostructure causes strong scattering of phonons with multiscale wavelengths, resulting in the decreased lattice thermal conductivity. The electrical conductivity is reduced while Seebeck coefficient is improved. As a result, a peak thermoelectric figure of merit (zT) of 1.73 with a calculated device efficiency of ~10.6% is achieved for the nanocomposites under the temperature range of 300–750 K.

Cu@Ag/Bi2Te3 nanocomposites were prepared for the first time by ultrasonic dispersion-rapid freeze-drying method combined with spark plasma sintering (SPS). By changing the content of Cu@Ag nanoparticle, we could modulate the temperature dependent thermoelectric properties. The highest ZT value can be obtained at 450 K for 1 vol% Cu@Ag/Bi2Te3, which is benefited from the decoupling of electrical and thermal properties. With the increase of electrical conductivity, the absolute value of Seebeck coefficient lifts while the thermal conductivity declines. Meanwhile, the average ZT value between 300 K and 475 K was 0.61 for 1 vol% Cu@Ag/Bi2Te3, which is much higher than that of pristine Bi2Te3. Therefore, the decoupling effect of Cu@Ag nanoparticles incorporation could be a promising method to broaden the application of Bi2Te3 based thermoelectric materials.

A kind of bismuth-doped silica glasses have been produced successfully by spark plasma sintering at 1070 °C using bismuth-doped SBA-15 powders. The samples were detected by X-ray diffraction, UV–vis–NIR, photoluminescence, fluorescent decay curve and X-ray photoelectron spectroscopy. The results showed that the samples possess favorable near-infrared fluorescence and the 0.9 mol% sample is the best one among these glasses. The emission peaks at ~1180, ~1150 and ~1250 nm can be observed when excited by 500, 700 and 800 nm. The average lifetimes of 0.9 mol% under 500, 700 and 800 nm excitation are 189.87, 311.46 and 132.16 μs. Furthermore, the value of the important optical parameter σemτ is 5.79 × 10−24 cm2s at 800 nm excitations, which is 36.8% and 9.2% larger than bismuth-doped germanate glasses and phosphate glasses that have been reported. These emission peaks could be decomposed into three bands at ~1150, ~1240 and ~1440 nm via Gaussian decomposition. Based on the results of this work, it is concluded that the NIR emission peaks at ~1150, ~1240 and ~1440 nm correspond to Bi0, Bi+ and (Bi2)2-, respectively. This glass with excellent luminescence properties could offer a practical material to improve the performance of broadband fiber amplifiers and tunable lasers.

A broad tunability of the thermoelectric and mechanical properties of CoSb3 has been demonstrated by adjusting the composition with the addition of an increasing number of elements. However, such a strategy may negatively impact processing repeatability and composition control. In this work, single-element-filled skutterudite is engineered to have high thermoelectric and mechanical performances. Increased Yb filling fraction is found to increase phonon scattering, whereas cryogenic grinding contributes additional microstructural scattering. A peak zT of 1.55 and an average zT of about 1.09, which is comparable to the reported results of multiple-filled SKDs, are realized by the combination of simple composition and microstructure engineering. Furthermore, the mechanical properties of Yb single-filled CoSb3 skutterudite are improved by manipulation of the microstructure through cryogenic grinding. These findings highlight the realistic prospect of producing high-performance thermoelectric materials with reduced compositional complexity. Keywords: Skutterudites, Thermoelectric material, Compositional complexity, Microstructure engineering, Cryogenic grinding

A highly textured pure Sb2Te3 is fabricated via a hydrothermal method combined with high-pressure spark plasma sintering. The nanoscale texture gives rise to an extremely low thermal conductivity in the out-of-plane direction, while shows weak influence on the carrier mobility which reaches the level of single crystal. Microstructure analysis reveals large amount of low-angle boundaries, whose discriminated effect on scattering phonons and carriers should account for the observed phenomenon. Consequently, the structurally nanocrystalline electrical monocrystalline behavior leads to a high average ZT with peak value above 1 at 525 K, which is the best TE performance for undoped Sb2Te3.

Self-healable polyurethanes (PUs) containing reversible dynamic bonds have been widely recognized and rapidly developed in recent years. Because the self-heal capability and mechanical properties of materials are mutually exclusive in nature, it is still a formidable challenge to design a highly efficient self-healable and robust PUs, especially in wearable electronics field. Herein, a series of self-healable thermosetting PU elastomer based on widely used phenolic urethane bond was prepared to achieve above requirements. In order to investigate the effect of introducing different bisphenol chain extenders into the hard segment domain on the dissociation temperature of phenolic carbamate bond, both bisphenol A (BPA) and bisphenol AF (BPAF) were used to synthesize thermosetting PU elastomers (PU-BPA and PU-BPAF). The healing efficiency of PU-BPA was 95% with a thermal treatment at 100 °C for 1 h, and its initial dissociation temperature was 90 °C. Due to the presence of trifluoromethyl (-CF3) group, the thermal self-healing efficiency of PU-BPAF was improved, which could be completely healed (100%) at the same conditions and its initial dissociation temperature was reduced to 80 °C. PU-BPAF were used to prepare a self-healable triboelectric nanogenerator (SH-TENG) to convert mechanical movements into electrical energy that can be applied to next-generation wearable devices.Their measured open circuit voltage, short circuit current, short-circuit charge quantity were 240 V, 2.20 μA, 20 nC, respectively. In addition, the PU-BPAF based SH-TENG exhibited better self-cleaning ability (83%) than that of PU-BPA elastomer, which was attributed to the introduction of trifluoromethyl reducing the surface energy of the material. Consequently, PU-BPAF showed great potentials as a self-healable and stretchable conductor to be applied to flexible electronic devices.

A series of silica glass compacts were prepared by rapid consolidation of zeolite powder using SPS under different conditions, and their photoluminescent properties were systematically studied in this work. XRD and high-energy synchrotron XRD results show that although the content of zeolite in glass decreases fast with increasing sintering temperature, the residual zeolite always can be found in obtained glass until 1300 °C. Moreover, despite the observed UV PL emission at ~ 370 nm for all prepared glass samples, the PL intensity decreases continuously with increasing consolidating temperature. Based on the FTIR results and HRTEM observation, it is deduced that the zeolite/glass interface which contains lots of defects plays a critical role for UV PL in the zeolite derived glass.

Dispersing the Ce3+ doped yttrium aluminum garnet (Ce:YAG) phosphor in the glass matrix has been widely investigated to replace conventional organic resin or silicone packaging. However, the reaction layer formed between commercial phosphors and glass matrix severely degrades the optical performance of Ce:YAG phosphor in silica glass (PiSG) materials. This paper demonstrates an ultra-fast method for preparing high performance PiSG materials. Instead of traditional melting process, the highly transparent PiSG samples can be rapidly fabricated from mixtures of commercial Ce:YAG phosphor and mesoporous SiO2 (SBA-15) powders using spark plasma sintering (SPS) at relatively low temperature (1000 °C) within short time (10 min). Owing to the inhibition of the deleterious interface reactions between Ce:YAG phosphor and silica glass matrix, the phosphor has been perfectly preserved, and the internal relative quantum yield of the PiSG sample reaches as high as 93.5% when excited at 455 nm, which is the highest efficiency in current research. Furthermore, combining the PiSG sample, we successfully fabricate a light-emitting diode (LED) module exhibiting a superior performance with luminous efficacy of 127.9 lm/W, correlated color temperature of 5877 K and color rendering index of 69 at the operating current of 120 mA. This work on the high performance LED modules provides not only a new approach to fabricate the functional glass-based materials that is sensitive to the high temperature, but also a possibility to extend the lifetime and improve the optical performances of the glass based LEDs.

Silica glasses dispersed with Pt nanoparticles and Ag nanoparticles are derived from solid-state sintering of mesoporous silica SBA-15 encapsulated with Pt nanoparticles and Ag nanoparticles, respectively. Using mesoporous powders for sintering is a facile method to lower synthesis temperature for glass making and to efficiently disperse noble metal nanoparticles in silica glass matrix. The included nanoparticles still play their functional roles in impacting on optical properties of the glass products prepared by this novel method. The glass dispersed with Pt nanoparticles exhibits brown color due to the interband electron transition of Pt nanoparticles. The coloring effect of surface plasmon resonance absorption from Ag nanoparticles colors the glass dispersed with Ag nanoparticles with yellow. Open-aperture and closed-aperture Z-scan methods are applied to measure third-order nonlinear absorption and refraction coefficient of the composite glasses, respectively, under femtosecond laser radiation at 880 nm wavelength. The glass dispersed with Pt nanoparticles behaves intense nonlinear absorption comparing with nonlinear refraction in magnitude, which could be attributed to interband electron transition by monophoton absorption of Pt nanoparticles. The glass dispersed with Ag nanoparticles shows stronger nonlinear refraction than saturated absorption. The dominant contribution to third-order optical nonlinearity of silica glass dispersed with Ag nanoparticles is intraband transition of free electrons near the Fermi surface of Ag nanoparticles. This method may have potential applications for fabricating silica glasses dispersed with ultrafine functional particles, which are potentially applicative in the fields of photonics.

Through the order–disorder transition process of zeolites, bismuth-doped zeolite-derived silica glasses with broadband near-infrared (NIR) photoluminescence have been successfully prepared by spark plasma sintering (SPS). The samples were characterized by X-ray diffraction, UV-vis, photoluminescence, and fluorescence lifetime. The results showed that as-prepared samples possessed favorable broadband NIR luminescence. The NIR emission (peaked at ~1140 nm) intensity decreased with increasing the bismuth doping concentration when excited by 500 and 700 nm. The tendency was different from the emissions (peaked at ~1240 nm) excited by 800 nm. In addition, the NIR fluorescence peaks of the fixed Bi concentration sample can be observed almost around 1140 or 1240 nm when excited by different wavelengths from 500 to 950 nm. These phenomena implied that the NIR emission peaked at different wavelengths may originate from different bismuth species. Three kinds of Bi active centers Bi+, Bi0, and (Bi2)2− were proposed to contribute to the NIR emission peaks at ~1140, 1240, and 1440 nm, respectively. Interestingly, a broadband NIR emission peaked at 1207 nm with a full-width at half maximum of 273 nm was observed when excited by 600 nm, whose intensity was stronger than that excited by 800 nm. This property might be useful for broadband fiber amplifiers and tunable lasers.

In this context, a one-pot and in situ strategy for fabrication of AgNPs (Ag nanoparticles)/PANI (polyaniline) nanocomposites in a micellar solution of dodecylbenzene sulfonic acid (DBSA, anionic surfactant) is introduced. Guided by this strategy, AgNPs were directly synthesized from silver nitrate. AgNPs/PANI hybrid nanocomposites with AgNPs were consolidated via spark plasma sintering (SPS). The phase structure and microstructure of the as-prepared composites were evaluated by several characterizations, and the growth mechanism of AgNPs was speculated. The thermoelectric properties of the samples with increasing silver nitrate content were systematically investigated. Compared with pure bulk PANI, the thermoelectric performance of AgNPs/PANI hybrid nanocomposites exhibits a distinct enhancement on the addition of AgNPs. The Seebeck coefficient (S) decreased slightly while the electric conductivity (σ) was found to increase remarkably. However, thermal conductivity (κ) remained unchanged with increasing silver nitrate content, which resulted in an obvious enhancement in the figure of merit (ZT) of the composites. Consequently, the maximum ZT of the AgNPs/PANI hybrid nanocomposites amazingly reached 5.73 × 10−5, which is about 3.8 times of the ZT of the pure PANI (1.503 × 10−5). This study suggests that the hybridization of organic/low-dimensional metal particles is promising to effectively improve the thermoelectric properties of conducting polymers.

Network protocol fuzzing tries to test the robustness of a protocol implementation through exploring the infinite amount of possible anomalous inputs to find the tests that cause invalid behaviors. Therefore, protocol fuzzing is regarded as security testing, since it is essential to prove robustness in networks. Although many good practices have been done to improve protocol fuzzing, problems in automated test case generation are still unsolved. Traditional methods using formal language and protocol specification have evident defects, especially in close networks. In order to provide useful references for test data generation, protocol reverse engineering becomes a suitable solution. But approaches adopted during the last decades cost much in computational complexity and time consumption. To break through these limitations, this paper proposes a novel message matrix perturbing mode to generate test case through data mutation for application layer protocol. It is established on the basis of the mapping relationship according to ASCII code. After the conversion from a protocol message to an integer matrix, meta-perturbations can be conducted to generate test data in all syntax levels, which preserves the flexibility in complex mutating combinations. Additionally, a new statistical keyword extracting technique with priority recursive splitting pattern is introduced to provide useful information for intelligent data mutation. Finally, we evaluate the method on HTTP request message. With the transformed message matrix and corresponding keyword reference, test cases examples for protocol fuzzing are generated through perturbing process with the combination of meta-operations. Fairly good outcomes are achieved which illustrate the feasibility and efficiency of the work in this paper.

Protocol testing has become the most vital part in the protocol engineering. Before protocol is deployed to Internet or communication network, all kinds of testing must be done with adequate test cases, while robustness testing is one of them. In this paper, we presented an integrate system for vulnerability testing with some improved techniques, such as extended Petri net, automatic test cases generation based on regular expression, syntax analysis method and so on. Finally, we implemented the testing system to Apache HTTP server 2.2 to evaluate its protocol robustness and vulnerability tolerance, and thereby verify our testing mode.