Search

The electrochemical production of hydrogen peroxide (H2O2) using metal‐free catalysts has emerged as a viable and sustainable alternative to the conventional anthraquinone process. However, the precise architectural design of these electrocatalysts poses a significant challenge, requiring intricate structural engineering to optimize electron transfer during the oxygen reduction reaction (ORR). Herein, we introduce a novel design of covalent organic frameworks (COFs) that effectively shift the ORR from a four‐electron to a more advantageous two‐electron pathway. Notably, the JUC‐660 COF, with strategically charge‐modified benzyl moieties, achieved a continuous high H2O2 yield of over 1200 mmol g−1 h−1 for an impressive duration of over 85 hours in a flow cell setting, marking it as one of the most efficient metal‐free and non‐pyrolyzed H2O2 electrocatalysts reported to date. Theoretical computations alongside in situ infrared spectroscopy indicate that JUC‐660 markedly diminishes the adsorption of the OOH* intermediate, thereby steering the ORR towards the desired pathway. Furthermore, the versatility of JUC‐660 was demonstrated through its application in the electro‐Fenton reaction, where it efficiently and rapidly removed aqueous contaminants. This work delineates a pioneering approach to altering the ORR pathway, ultimately paving the way for the development of highly effective metal‐free H2O2 electrocatalysts. [ABSTRACT FROM AUTHOR]

The electrochemical production of hydrogen peroxide (H2O2) using metal‐free catalysts has emerged as a viable and sustainable alternative to the conventional anthraquinone process. However, the precise architectural design of these electrocatalysts poses a significant challenge, requiring intricate structural engineering to optimize electron transfer during the oxygen reduction reaction (ORR). Herein, we introduce a novel design of covalent organic frameworks (COFs) that effectively shift the ORR from a four‐electron to a more advantageous two‐electron pathway. Notably, the JUC‐660 COF, with strategically charge‐modified benzyl moieties, achieved a continuous high H2O2 yield of over 1200 mmol g−1 h−1 for an impressive duration of over 85 hours in a flow cell setting, marking it as one of the most efficient metal‐free and non‐pyrolyzed H2O2 electrocatalysts reported to date. Theoretical computations alongside in situ infrared spectroscopy indicate that JUC‐660 markedly diminishes the adsorption of the OOH* intermediate, thereby steering the ORR towards the desired pathway. Furthermore, the versatility of JUC‐660 was demonstrated through its application in the electro‐Fenton reaction, where it efficiently and rapidly removed aqueous contaminants. This work delineates a pioneering approach to altering the ORR pathway, ultimately paving the way for the development of highly effective metal‐free H2O2 electrocatalysts. [ABSTRACT FROM AUTHOR]

The extremely low melt flowability of ultra‐high molecular weight polyethylene (UHMWPE) is the primary obstacle to its melt processing. Particularly in melt spinning processes, the extremely high molecular weight of UHMWPE and the density of entangled molecular chains severely limit its production efficiency and monofilament performance. This study investigates the effect of flow modifiers on the melt spinning process of UHMWPE/HDPE blends, focusing on CaSt2, PEG, and CaSt2/silicone powder composite additives, and their impact on the standard tensile samples and monofilament tensile properties of UHMWPE/HDPE. The mechanism of additive influence on the tensile properties of UHMWPE/HDPE blends is analyzed through tensile strength testing, thermal analysis, and microscopic morphology observation. The results show that in standard tensile samples, CaSt2 or CaSt2/silicone powder composite additives can enhance the crystallinity of the blend, thereby improving its tensile strength. Conversely, adding PEG significantly reduces the crystallinity and tensile strength of the blend. The maximum tensile strength of CaSt2‐modified UHMWPE/HDPE monofilament is 1236.61 MPa. This enhancement is attributed to the lubricating effect of CaSt2, which simultaneously assists the molecular chains in the amorphous region, and the reorientation of the stress‐induced molten lamellar structure under tension, greatly promoting the formation of straight‐chain crystals in the monofilament. During hot drawing, PEG inhibits the formation of straight‐chain crystals in the monofilament, resulting in a 3.06% decrease in maximum crystallinity compared with standard tensile samples. When CaSt2 is combined with silicone powder, the additives tend to aggregate during hot drawing, and these larger aggregate particles hinder the orientation of molecular chains along the drawing direction, resulting in a 30.75% decrease in maximum tensile strength of the monofilament compared with the standard tensile samples. Highlights: The tensile property of UHMWPE/HDPE blends modified with additives was discussed.Analytical techniques including DSC, SEM, and tensile strength tests were used.The maximum tensile strength of the monofilament can reach up to 1236.61 MPa.UHMWPE/HDPE/CaSt2 = 60/40/0.5 exhibits the best tensile property. [ABSTRACT FROM AUTHOR]

In this work, the microstructure evolution and corrosion performance of additively manufactured GH4099 superalloy were investigated. The alloy samples were prepared by selective laser melting (SLM) technology with different laser power and scanning speed. The results showed that the GH4099 prepared by SLM had a fine grain structure, and the average grain size of all samples is below 18 μm. The relative density of SLMed samples first rose and then fell as the volume density increased. Under the process conditions of P = 170 W and V = 800 mm/s, sample N2 possessed the highest relative density and the minimum pores. In addition, the electrochemical test results indicated that sample N2 exhibited the best corrosion resistance, and its corrosion potential (ECorr) and corrosion current density (ICorr) were − 0.287 V and 0.149 μA·cm−2, respectively. The relative density and pores of the alloys were the main reason for the difference in corrosion properties. In particular, the irregular pores caused by lack of fusion were regarded as the initiation site of pitting and crack expansion, which has a greater effect on corrosion resistance than spherical pores. According to XPS results, the passivation film mainly consists of oxides and hydroxides of Ni, Cr, Co, and Al. The hydroxides of Ni, Cr, Co, and Al constituted the outer layer of the passivation film. After the dehydration reaction of hydroxides, their oxides formed the inner layer of the passivation film. In addition, the evolution of the passivation film including the formation and breakdown of the passivation film was also discussed. [ABSTRACT FROM AUTHOR]

The challenging melt processing of ultrahigh‐molecular‐weight polyethylene (UHMWPE) melt spinning hinders its efficiency and quality, which can be improved by processing aids that enhance its flowability. Building upon modifications of UHMWPE with high‐density polyethylene (HDPE), this article studies the effects of CaSt2, polyethylene glycol (PEG), silicone powder, and their compound additives on the processing performance of UHMWPE/HDPE blends. The modification effects and mechanisms are studied by analyzing processing torque, melt flow rate, viscoelastic activation energy, and rheological performance. The research results indicate that 1 wt% PEG significantly improves the processing flowability of UHMWPE/HDPE blends, and PEG mainly plays an internal lubrication role on the molecular chains of the blends. The combination of 0.5 wt% CaSt2 and 0.5 wt% silicone powder exhibits a synergistic effect of internal and external lubrication on the UHMWPE/HDPE blends melt processing, further improving the processing performance of UHMWPE/HDPE blends. Compared with unmodified blends, the maximum screw speed for obtaining qualified as‐spun filaments of UHMWPE/HDPE blends modified with CaSt2/silicone powder compound additives increases from 5 to 20 rpm, which means that the critical shear rate of the modified UHMWPE/HDPE blend melt processing is significantly improved. Meanwhile, the processing torque decreases by about 22%. [ABSTRACT FROM AUTHOR]

This article discusses the development of an improved and eco-friendly synthesis method for (R)-5,7-difluorochroman-4-ol, a key intermediate in the production of Tegoprazan, a medication used to treat acid-related diseases. The researchers optimized the reaction conditions and achieved a high yield and purity of the desired product using lipase-catalyzed resolution and Mitsunobu inversion. This method shows promise for practical use in the green synthesis of Tegoprazan due to its efficiency and environmental sustainability. The document provides a detailed account of the synthesis process and acknowledges financial support from the CQMU Program for Youth Innovation in Future Medicine. [Extracted from the article]

Solar-driven photocatalytic hydrogen generation via splitting water requires an efficient visible light active photocatalyst. In this work, Ni cocatalysts on a TiO2 composite photocatalyst with different graphene oxide (GO) contents were prepared using a hydrothermal method and characterized by TEM, XRD, UV-vis, Raman and PL spectra. The results show that the synthesized TiO2/GO/Ni nanosheet composites have a large specific surface area and can provide a large number of active sites for a photocatalytic hydrogen production reaction. GO can broaden the optical absorption range of TiO2 and absorb more visible light, thus stimulating more photogenerated electron–hole pairs. At the same time, GO can collect electrons and promote the separation of photogenerated electron–hole pairs. Ni, as a cocatalyst, can be used as an active site for hydrogen ion adsorption, which is conducive to promoting the migration of photogenerated electrons in the system and prolonging the life of photogenerated electrons and holes, thus ensuring the high efficiency of the photocatalytic reaction. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries (AZIBs) have received great attention owing to the increasing demand for safe and inexpensive batteries. However, their poor cycling issue hinders their commercialization and further application, resulting from the zinc dendrite growth, corrosion, and passivation that occur on the Zn anode, as well as the dissolution and cracking issue of active materials on the cathode. Herein, we introduce the use of a chelating agent triethanolamine (TEA) as an additive in the electrolyte to enhance the cycling stability of AZIBs. TEA molecules preferentially coordinate with Zn2+, replacing water molecules in the solvation sheath of Zn2+, thereby reducing the solvation effect in the electrolyte. Moreover the adsorbed interface layer on the anode Zn surface forms a stable solid–electrolyte interphase (SEI) while the cathode forms a cathode–electrolyte interphase (CEI), suppressing the side reactions and dendrite growth of metallic Zn and protecting the cathode from dissolution while increasing the diffusion rate of Zn2+. The Zn‖MnO2@CNT cell showed reversible and durable performance with 78% retention after 2000 cycles at 0.5 A g−1. [ABSTRACT FROM AUTHOR]

Purpose: First, the authors analyze the key problems faced by the protection of digital library readers' data privacy and behavior privacy. Second, the authors introduce the characteristics of all kinds of existing approaches to privacy protection and their application limitations in the protection of readers' data privacy and behavior privacy. Lastly, the authors compare the advantages and disadvantages of each kind of existing approaches in terms of security, efficiency, accuracy and practicality and analyze the challenges faced by the protection of digital library reader privacy. Design/methodology/approach: In this paper, the authors review a number of research achievements relevant to privacy protection and analyze and evaluate the application limitations of them in the reader privacy protection of a digital library, consequently, establishing the constraints that an ideal approach to library reader privacy protection should meet, so as to provide references for the follow-up research of the problem. Findings: As a result, the authors conclude that an ideal approach to reader privacy protection should be able to comprehensively improve the security of all kinds of readers' privacy information on the untrusted server-side as a whole, under the premise of not changing the architecture, efficiency, accuracy and practicality of a digital library system. Originality/value: Along with the rapid development of new network technologies, such as cloud computing, the server-side of a digital library is becoming more and more untrustworthy, thereby, posing a serious threat to the privacy of library readers. In fact, the problem of reader privacy has become one of the important obstacles to the further development and application of digital libraries. [ABSTRACT FROM AUTHOR]

Ultra‐high molecular weight polyethylene monofilament is prepared by melt spinning. Differential scanning calorimetry, X‐ray diffraction, scanning electron microscopy, and tensile testing are used to characterize the crystallinity, crystal form, surface morphology, and tensile strength of the monofilament at various draw temperatures and ratios, as well as the interaction between them. The lamellar crystal structure in the fiber is stable at lower draw temperatures, and an excessive draw ratio will aggravate the stress concentration of the intergranular molecular chain in the drawing process, which can easily lead to microfiber fracture. Increasing the draw temperature encourages not only molecular chain disentanglement in the amorphous region of the fiber, but it can also weaken the crystal structure constraint on molecular chain activity, promote the transformation of lamellar structure into extended chain structure, and improve the loadable draw ratio. The elevated draw ratio drives the orientation of the molecular chain, the crystal structure is motivated to draw along the axis, and the crystal grains are refined, resulting in a more compact internal structure of the fiber. Excessive temperature causes drastic changes in the internal structure of the fiber, which is detrimental to improving draw ratio and fiber strength. [ABSTRACT FROM AUTHOR]

In this work, the thermal stability of nanocrystalline (NC) AZ31/TiB2 magnesium matrix composites was investigated, while the microstructure evolution and mechanical properties were analyzed. The results indicated the AZ31/TiB2 still maintained NC structure after annealing at 350 °C for 180 min. Even at the high annealing temperature of 400 °C and 450 °C for 180 min, their average grain size just reached about 124 nm and 155 nm, indicating excellent thermal stability. The TiB2 particles with sub-micron size uniformly distributed in Mg matrix had no change in size and no reaction with matrix during the annealing treatment. Due to the strong Zener pinning effect of TiB2 particles, the grain growth of Mg matrix at high temperature was effectively inhibited. Meanwhile, the solution and precipitation behavior of Al atoms were completed in a short time, due to the existence of many grain boundaries and structural defects. By calculation, the grain growth kinetics was described by the kinetics equation D 8 - D 0 8 = k t and the activation energy Eg for grain growth was 131.6 kJ/mol, which was much higher than that of pure Mg (92 kJ/mol). Due to their excellent thermal stability, the decrease in both compressive yield strength and ultimate compressive strength was no more than 12.2% after annealing treatment. Even annealing at 450 °C for 180 min, the CYS and UCS of the samples were still above 283 MPa and 295 MPa, respectively. [ABSTRACT FROM AUTHOR]

In the context of globalization, the international common language is English and it is more and more widely used. However, there is a shortage of talents with high English proficiency in all industries. According to the demand of the Chinese market, we should pay attention to students' English language ability. Deep learning is a machine learning method based on feature learning and feature hierarchical structure, which simulates the analysis and learning of the human brain, carries out feature transformation layer by layer, trains a single-layer network each time, and transforms the features of samples in the original space to a new feature space, thus making classification or prediction easier. There are still some defects in the current machine translation (MT) results of online MT, especially the disadvantages of low efficiency and low accuracy of MT when the full-text range uses the server to compare the data of different languages to obtain the grammar and text-related rules among different languages. Therefore, other modern intelligent recognition technologies should be adopted to achieve accurate English MT. Generally speaking, the closer the training data is to the domain of the target text, the higher the quality of sentence alignment and the more sentence pairs, the more helpful it is to learn more accurate translation rules, so as to obtain a more robust translation. [ABSTRACT FROM AUTHOR]

Microcellular foaming with CO2 as the blowing agent is developed to prepare low‐density ultrahigh molecular weight polyethylene (UHMWPE) foams. To improve the foaming behavior of UHMWPE, silicone powder is used to modify UHMWPE by twin‐screw compounding. The silicone powder contents, foaming temperatures, and foaming pressures are varied to investigate their effect on the foaming behavior of UHMWPE in a one‐step microcellular foaming process. The results show that the addition of silicone powder leads to significantly improved foaming behavior of UHMWPE by simultaneously increasing the expansion ratio and refining cellular morphology. With the presence of silicone powder, UHMWPE with an expansion ratio up to 34‐fold is prepared, while the maximum expansion ratio of pure UHMWPE foam that can be achieved is only 15‐fold. Moreover, for the foams with the same expansion ratio, the presence of silicone powder leads to significantly refined cellular morphology. The improved melt flowability and accelerated crystallization by adding silicone powder are responsible for the significantly enhanced foaming ability of UHMWPE. The heterogeneous nucleation effect of silicone powder plays a critical role in refining the cellular morphology by promoting cell nucleation and reducing cell collapse. [ABSTRACT FROM AUTHOR]

A novel protocol for the direct halogenation of 8‐amidoquinoline derivatives with phase‐transition was reported. The reactions were promoted by benzyltriethylammonium chloride and dihalogenated hydantoin, using exclusively water as the solvent and achieving the C5‐halogenation products of amidoquinolines in moderated to excellent yields at room temperature. [ABSTRACT FROM AUTHOR]

We present detailed investigations of structural and static/dynamic magnetic properties of hydrogenated hcp-Co8057Fe4Ir16 soft magnetic thin films. Two different kinds of defects, i.e., destructive and non-destructive, were demonstrated by controlling the negative bias voltage of the hydrogenation process. Our results show that the structure and magnetic properties of our sample can be tuned by the density of the induced defects. These results provide better understanding of the hydrogenation effect and thus can be used in the future for materials processing to meet the requirements of different devices. [ABSTRACT FROM AUTHOR]

Manganites (R1−xAxMnO3, R = rare-earth cation and A = alkali or alkaline earth cation) host an immense number of phases and electronic properties, which can be mainly manipulated through conventional structural control such as metallic cations, oxygen concentration, or misfit strain. However, their practical applications are heavily hindered due to the requirement of rigid synthesis conditions and prolonged treatment time. Herein, a subtle hydrogenation of canonical epitaxial La0.3Sr0.7MnO3 films gives rise to a series of structural transformations ranging from the perovskite to the intermediate state and to the brownmillerite one, accompanied by tunable electronic performances from the antiferromagnetic insulating phase to the weak magnetic insulating one. Moreover, the hydrogenated La0.3Sr0.7MnO3−δ films show an ultra-high magnetic temperature (>400 K). The efficient modulations of the crystalline structure and functionalities of manganite oxides using the facile hydrogenation process enable practical applications of high-temperature magnetic insulators in spintronic devices. [ABSTRACT FROM AUTHOR]

Two kinds of Fe/amorphous carbon (a-C) submicron fibers were prepared by electrospinning using polyvinylpyrrolidone (PVP) and polyacrylonitrile (PAN) as precursor polymer, followed by carbonization under the same conditions. Contributed to the different reaction mechanisms during the annealing process, different phases namely graphite carbon (g-C) and Fe4N formed at the interface between the Fe nanoparticles and the a-C matrix. Electromagnetic absorption properties have shown that the Fe@Fe4N submicron fibers have superior absorption performance than the Fe@g-C ones. The minimal reflection loss (RL) value of the former is − 39.8 dB at 5.4 GHz with the absorber thickness of 5.0 mm, and the effective absorption bandwidth (RL ≤ − 10 dB) can reach 5.0 GHz when the absorber thickness is 2.5 mm. By contrast, the Fe@g-C submicron fibers have little absorption. The attenuation constant, impedance matching coefficient, complex permittivity and complex permeability were investigated in detail. The microstructure and composition were explored various superior tools. The results revealed that the interface Fe4N has a critical role in affecting the magnetic loss and dielectric loss, which brings better impedance matching and relatively low dielectric loss. Therefore, the Fe@Fe4N submicron fibers have excellent microwave absorbing properties. [ABSTRACT FROM AUTHOR]

Abstract: Efficient and affordable synthesis of graphene at low temperatures remains a significant challenge that potentially limits the use of this material in real‐life applications. We describe here a simple, efficient, highly controllable technique to synthesize graphene by sputtering carbon from a solid source with the assistance of inductively coupled plasma (ICP), followed by controllable low‐temperature annealing at about 550 oC. Raman scattering and X‐ray diffraction characterizations have revealed the formation of a few layer graphene of high quality, confirmed by a low (∼0.48) ID/IG ratio. Raman analysis of samples formed at various annealing temperatures has revealed an upper limit for annealing temperature of 585 oC, beyond which the formed graphene reversibly dissolves in the metal. The ICP‐assisted process was innovatively employed to improve the quality of thus‐fabricated graphene at low temperatures. The mechanism of graphene formation was attributed to the metal induced graphitization in combination with the carbon precipitation onto the catalyst surface. [ABSTRACT FROM AUTHOR]

DP antagonists are claimed to be useful in the treatment of allergic disorders. Laropiprant is a potent and selective DP antagonist to reduce the allergic disorders, especially niacin-induced flushing. In our study, a series of novel laropiprant derivatives (I-1- I-18) were synthesized and characterized by IR, H-NMR, C-NMR and HRMS spectrum. The potency of these compounds was evaluated in a murine model of niacin-induced flushing. The results indicated that most compounds exhibited faster-acting effect of suppressing vasodilation than laropiprant. Among them, I-1, I-2, I-3, I-9, I-13, I-15 and I-16 exhibited substantial flushing inhibitory effect. Especially, I-1 and I-2 showed higher potency than laropiprant and would be valuable for further investigation. [ABSTRACT FROM AUTHOR]

The reaction pathway as well as the mechanism of the solid state reaction between MgH2 and AlCl3 has been a mystery so far. Based on SEM, TEM and NMR (Nuclear Magnetic Resonance) analyses, an amorphous intermediate (AlH6)n was preferentially formed and recrystallized as a γ phase at the final stage of the reaction. As a novel finding, this research provides a deep insight into the process and mechanism of this mechanically activated reaction. [ABSTRACT FROM AUTHOR]

An efficient synthetic method for 2, 3-dihydro-1 H-indene-1-methanamine and its derivatives is described. Six compounds of 2, 3-dihydro-1 H-indene-1-methanamines were synthesized from corresponding 4-nitro-3-phenylbutanoic acid in satisfactory yields (50.9-57.9 % in 4 steps), and three compounds ( 1c, 1e, 1f) were newly reported. This procedure has the advantages of mild conditions, less pollution, and simple manipulation. [ABSTRACT FROM AUTHOR]

Although formation of urothelial carcinoma of the bladder (UCB) requires multiple steps and proceeds along divergent pathways, the underlying genetic and molecular determinants for each step and pathway remain undefined. By developing transgenic mice expressing single or combinatorial genetic alterations in urothelium, we demonstrated here that overcoming oncogene-induced compensatory tumor barriers was critical for urothelial tumor initiation. Constitutively active Ha-ras (Ras*) elicited urothelial hyperplasia that was persistent and did not progress to tumors over a 10 months period. This resistance to tumorigenesis coincided with increased expression of p53 and all pRb family proteins. Expression of a Simian virus 40 T antigen (SV40T), which disables p53 and pRb family proteins, in urothelial cells expressing Ras* triggered early-onset, rapidly-growing and high-grade papillary UCB that strongly resembled the human counterpart (pTaG3). Urothelial cells expressing both Ras* and SV40T had defective G1/S checkpoint, elevated Ras-GTPase and hyperactivated AKT-mTOR signaling. Inhibition of the AKT-mTOR pathway with rapamycin significantly reduced the size of high-grade papillary UCB but hyperactivated mitogen-activated protein kinase (MAPK). Inhibition of AKT-mTOR, MAPK and STAT3 altogether resulted in much greater tumor reduction and longer survival than did inhibition of AKT-mTOR pathway alone. Our studies provide the first experimental evidence delineating the combinatorial genetic events required for initiating high-grade papillary UCB, a poorly defined and highly challenging clinical entity. Furthermore, they suggest that targeted therapy using a single agent such as rapamycin may not be highly effective in controlling high-grade UCB and that combination therapy employing inhibitors against multiple targets are more likely to achieve desirable therapeutic outcomes. [ABSTRACT FROM AUTHOR]

It is found that silver nanoparticles (AgNPs) can further enhance the fluorescence intensity of curcumin (CU) - cetyltrimethylammonium bromide (CTAB) – nucleic acids and improve its anti-photobleaching activity. Under optimum conditions, the enhanced fluorescence intensity is proportion to the concentration of nucleic acids in the range of 2.0 × 10−8–1.0 × 10−6 g mL−1 for fish sperm DNA (fsDNA), 2.0 × 10−8–1.0 × 10−6 g mL−1 for calf thymus DNA (ctDNA), 1.0 × 10−8–1.0 × 10−6 g mL−1 for yeast RNA (yRNA), and their detection limits (S/ N = 3) are 8.0 ng mL−1, 10.5 ng mL−1 and 5.8 ng mL−1, respectively. This method is used for determining the concentration of DNA in actual sample with satisfactory results. The interaction mechanism is also studied. [ABSTRACT FROM AUTHOR]

This article describes a process flow that has enabled the first demonstration of functional, fully self-aligned 100 nm enhancement mode GaAs metal-oxide-semiconductor field-effect transistors (MOSFETs) with GaxGdyOz as high-κ dielectric, Pt/W as metal gate stack, and SiN as sidewall spacers. The flow uses blanket metal and dielectric deposition and low damage dry etch modules. As a consequence, no critical dimension lift-off processes are required. Encouraging data are presented for 100 nm gate length devices including threshold voltage of 0.32 V, making these the shortest, fully self-aligned gate length enhancement mode III-V MOSFETs reported to date. This work is a significant step forward to the demonstration of high performance “siliconlike” III-V MOSFETs. [ABSTRACT FROM AUTHOR]

Nucleic acid can greatly enhance the fluorescence intensity of quercetin in HMTA-HCl (pH 5.5) buffer. The enhanced intensity is in proportion to the concentration of nucleic acids in the range 5.0 × 10−9 to 1.0 × 10−6 g/mL for fsDNA, 5.0 × 10−9 to 7.0 × 10−7 g/mL for ctDNA and 5.0 × 10−9 to 1.0 × 10−6 g/mL for yRNA, and their detection limits (S/N = 3) are 3.5 × 10−9, 7.8 × 10−10 and 2.6 × 10−9 g/mL, respectively. In comparison with most reported fluorescent probes for the determination of nucleic acids, the proposed probe has higher sensitivity and lower toxicity. The interaction investigation indicates that quercetin binds with double-strand DNA in groove binding mode, resulting in fluorescence enhancement of this system. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this work, vanadium particles (VP) were utilized as a novel reinforcement of AZ31 magnesium (Mg) alloy. The nanocrystalline (NC) AZ31–VP composites were prepared via mechanical milling (MM) and vacuum hot-press sintering. During the milling process, the presence of VP contributed to the cold welding and fracture mechanism, resulting in the acceleration of the milling process. Additionally, increasing the VP content accelerated the grain refinement of the matrix during the milling process. After milling for 90 h, the average grain size of AZ31-X wt % Vp (X = 5, 7.5, 10) was refined to only about 23 nm, 19 nm and 16 nm, respectively. In the meantime, VP was refined to sub-micron scale and distributed uniformly in the matrix, exhibiting excellent interfacial bonding with the matrix. After the sintering process, the average grain size of AZ31-X wt % VP (X = 5, 7.5, 10) composites still remained at the NC scale, which was mainly caused by the pinning effect of VP. Besides that, the porosity of the sintered composites was no more than 7.8%, indicating a good densification effect. As a result, there was little difference between the theoretical and real density. Compared to as-cast AZ31 Mg alloy, the microhardness of sintered AZ31-X wt % VP (X = 5, 7.5, 10) composites increased by 65%, 87% and 96%, respectively, owing to the strengthening mechanisms of grain refinement strengthening, Orowan strengthening and load-bearing effects. [ABSTRACT FROM AUTHOR]

A new high-performance normally-off gallium nitride (GaN)-based metal–oxide–semiconductor high electron mobility transistor that employs an ultrathin subcritical 3 nm thick aluminium gallium nitride (Al0.25Ga0.75N) barrier layer and relies on an induced two-dimensional electron gas for operation is presented. Single finger devices were fabricated using 10 and 20 nm plasma-enhanced chemical vapor-deposited silicon dioxide (SiO2) as the gate dielectric. They demonstrated threshold voltages (V \(_{\mathrm {\mathbf {th}}}\) ) of 3 and 2 V, and very high maximum drain currents (I \(_{\mathrm {\mathbf {DSmax}}}\) ) of over 450 and 650 mA/mm, at a gate voltage (V \(_{\mathrm {\mathbf {GS}}}\) ) of 6 V, respectively. The proposed device is seen as a building block for future power electronic devices, specifically as the driven device in the cascode configuration that employs GaN-based enhancement-mode and depletion-mode devices. [ABSTRACT FROM AUTHOR]

In this letter, we investigate the scaling potential of flatband III–V MOSFETs by comparing the mobility of surface- and buried-channel \In0.53\Ga0.47\As devices employing an atomic-layer-deposited \Al2 \O3 gate dielectric and a delta-doped InGaAs/InAlAs/InP heterostructure. Peak electron mobilities of 4300 \cm^2/\V\cdot \s and 6600 \cm^2/\V\cdot \s at a carrier density of \3 \times \10^12\ \cm^-2 were determined for the surface- and buried-channel structures, respectively. In contrast to similarly scaled inversion-channel devices, we find that the mobility in surface-channel flatband structures does not drop rapidly with the electron density, but rather high mobility is maintained up to carrier concentrations around \4 \times \10^12\ \cm^-2 before slowly dropping to around 2000 \cm^2/\V \cdot \s at \1 \times \10^13\ \cm^-2. We believe these to be world leading metrics for this material system and an important development in informing the III–V MOSFET device architecture selection process for the future low-power highly scaled CMOS. [ABSTRACT FROM AUTHOR]

The influence of electropulsing treatment (EPT) parameters on the static recrystallization (SRX) microstructure in a cold-deformed Ni-based superalloy was investigated. During EPT, both the volume fraction of SRX grains and the average grain size increased with the increasing EPT temperature, which was attributed to the thermal effect and athermal effect induced by EPT. The mobility of SRX grain boundaries was promoted at the higher temperature due to the thermal effect, while the nucleation rate would be increased by EPT through decreasing the thermodynamic barrier. The formation of parallel dislocations caused by electron wind force could also play an indirect role in promoting SRX process. Moreover, the volume fraction of SRX grains increased significantly with the extension of EPT time at 700 °C, while the EPT time had a trivial effect on the average grain size. In addition, the sufficient deformation was essential to the occurrence of SRX behavior during EPT, and the localized Joule heating effect could promote the SRX behavior in the samples with the larger strains. Besides that, the influence of twining and carbides on the SRX behaviors was also investigated. [ABSTRACT FROM AUTHOR]

In this work, nanocrystalline AZ31 magnesium alloy powders, reinforced by submicron TiB2 particles, were prepared via mechanical milling. It was found that TiB2 particles stimulated the fracture and welding of AZ31/TiB2 powders, leading to the acceleration of the milling process. Meanwhile, the TiB2 particles were refined to submicron-scale size during the milling process, and their distribution was uniform in the Mg matrix. In addition, the matrix was significantly refined during the milling process, which was also accelerated by the TiB2 particles. The formation of grain boundary segregation layers also led to the weakened TiB2 peaks in the XRD patterns during the mechanical milling. The grain sizes of AZ31–2.5 wt % TiB2, AZ31–5 wt % TiB2 and AZ31–10 wt % TiB2 powders were refined to 53 nm, 37 nm and 23 nm, respectively, after milling for 110 h. Under the combined effect of the nanocrystalline matrix and the well-dispersed submicron TiB2 particles, the AZ31/TiB2 composites exhibited excellent micro-hardness. For the AZ31–10 wt % TiB2 composite, the micro-hardness was enhanced to 153 HV0.5. [ABSTRACT FROM AUTHOR]

Hydrogenation of transition metal oxides offers a powerful platform to tailor physical functionalities as well as for potential applications in modern electronic technologies. An ideal nondestructive and efficient hydrogen incorporation approach is important for the realistic technological applications. We demonstrate the proton injection on SrCrO3 thin films via an efficient low-energy hydrogen plasma implantation experiments, without destroying the original lattice framework. Hydrogen ions accumulate largely at the interfacial regions with amorphous character which extend about one-third of the total thickness. The HxSrCrO3 (HSCO) thin films appear like exfoliated layers which however retain the fully strained state with distorted perovskite structure. Proton doping induces the change of Cr oxidation state from Cr4+ to Cr3+ in HSCO thin films and a transition from metallic to insulating phase. Our investigations suggest an attractive platform in manipulating the electronic phases in proton-based approaches and may offer a potential peeling off strategy for nanoscale devices through low-energy hydrogen plasma implantation approaches. [ABSTRACT FROM AUTHOR]

The ability to tailor a new crystalline structure and associated functionalities with a variety of stimuli is one of the key issues in material design. Developing synthetic routes to functional materials with partially absorbed nonmetallic elements (i.e., hydrogen and nitrogen) can open up more possibilities for preparing novel families of electronically active oxide compounds. Fast and reversible uptake and release of hydrogen in epitaxial ABO3 manganite films through an adapted low‐frequency inductively coupled plasma technology is introduced. Compared with traditional dopants of metallic cations, the plasma‐assisted hydrogen implantations not only produce reversibly structural transformations from pristine perovskite (PV) phase to a newly found protonation‐driven brownmillerite one but also regulate remarkably different electronic properties driving the material from a ferromagnetic metal to a weakly ferromagnetic insulator for a range of manganite (La1−xSrxMnO3) thin films. Moreover, a reversible perovskite‐brownmillerite‐perovskite transition is achieved at a relatively low temperature (T ≤ 350 °C), enabling multifunctional modulations for integrated electronic systems. The fast, low‐temperature control of structural and electronic properties by the facile hydrogenation/dehydrogenation treatment substantially widens the space for exploring new possibilities of novel properties in proton‐based multifunctional materials. [ABSTRACT FROM AUTHOR]

This paper presents a low damage inductively coupled plasma (ICP) etching process to define sub-100 nm platinum gate lines for III–V metal–oxide–semiconductor field-effect transistors (MOSFETs) fabrication. In this process, a negative resist etching mask patterned by electron beam lithography is used to define the high resolution platinum features using a combination of SF6 and C4F8 etch gases. Systematic investigation of the impact of various etch conditions, such as coil and platen power, gas composition, chamber pressure on etch rate and profile, resulted in a controllable etching process. Optical emission spectra of the ICP plasma have been checked for better understanding the etching mechanism. Etch induced damage of the underlying device channel of the III–V MOSFET materials has been evaluated through monitoring the sheet resistance variation of the materials at room temperature, which showed the process does not significantly degrade the electrical properties of the underlying device channel under optimized conditions. [ABSTRACT FROM AUTHOR]