A General Method for the Chemical Synthesis of Large‐Scale,Seamless Transition Metal Dichalcogenide Electronics

The capability to directly build atomically thin transition metal dichalcogenide (TMD) devices by chemical synthesis offers important opportunities to achieve large‐scale electronics and optoelectronics with seamless interfaces. Here, a general approach for the chemical synthesis of a variety of TMD (e.g., MoS₂, WS₂, and MoSe₂) device arrays over large areas is reported. During chemical vapor deposition, semiconducting TMD channels and metallic TMD/carbon nanotube (CNT) hybrid electrodes are simultaneously formed on CNT‐patterned substrate, and then coalesce into seamless devices. Chemically synthesized TMD devices exhibit attractive electrical and mechanical properties. It is demonstrated that chemically synthesized MoS₂–MoS₂/CNT devices have Ohmic contacts between MoS₂/CNT hybrid electrodes and MoS₂ channels. In addition, MoS₂–MoS₂/CNT devices show greatly enhanced mechanical stability and photoresponsivity compared with conventional gold‐contacted devices, which makes them suitable for flexible optoelectronics. Accordingly, a highly flexible pixel array based on chemically synthesized MoS₂–MoS₂/CNT photodetectors is applied for image sensing.     

Carbon nanotube substrates boost neuronal electrical signaling

We demonstrate the possibility of using carbon nanotubes (CNTs) as potential devices able to improve neural signal transfer while supporting dendrite elongation and cell adhesion. The results strongly suggest that the growth of neuronal circuits on a CNT grid is accompanied by a significant increase in network activity. The increase in the efficacy of neural signal transmission may be related to the specific properties of CNT materials, such as the high electrical conductivity.     

Influence of aggregate content on the percolated interfacial transition zone of cement‐based materials by using accelerated chloride migration test

Abstract

In this study, the effect of the aggregate content on the chloride migration coefficient at the percolated interfacial transition zone (ITZ) was studied in cement‐based materials. Specimens with three different water‐to‐cement ratios and five different aggregate volume fractions were used. The chloride migration coefficient was measured with the accelerated chloride migration test (ACMT). A three‐phase composite model was used to determine the approximate chloride migration coefficient at the percolated ITZ. The results showed that the approximate chloride migration coefficient at the percolated ITZ increased significantly as more rod‐shaped aggregate was used in the mortar.     

氯化钙改性硅胶吸湿材料的制备及性能研究

目的 针对水溶液改性硅胶基质易破裂,普通硅胶吸水率不高等问题,采用氯化钙醇溶液浸渍法制备不同浓度的氯化钙改性硅胶吸湿材料。方法 对比采用氯化钙水溶液和醇溶液制备的氯化钙改性硅胶吸湿材料的外观质量;采用气体吸附法测试等温吸附脱附曲线,基于吸附理论和FHH模型获得氯化钙改性硅胶吸湿材料孔隙参数和分形维数;采用静态吸附法获得水蒸气静态吸附曲线,根据准一级和准二级动力学模型建立适用于氯化钙改性硅胶吸湿材料的吸附动力学方程。结果 采用氯化钙醇溶液浸渍制备的氯化钙改性硅胶吸湿材料的破裂程度明显减少;比表面积和孔容随氯化钙含量的增加而减小,孔径变化较小;吸湿量随氯化钙含量的增加而增加。在模拟吸附过程中,准二级动力学模型相关系数更高,因此能更好地模拟吸附动力学过程。结论 采用质量分数为25%的氯化钙醇溶液制备的氯化钙改性硅胶吸湿材料的吸湿率最高、基质破裂率较低、再生能力优异,具有良好的应用前景。     

Chloride Ion Mediated Synthesis of Metal/Semiconductor Hybrid Nanocrystals

A synthetic route to prepare metal–semiconductor hybrid nanoparticles is presented, along with the possibility to tune the ratio of primary to secondary nucleation and the morphology of the semiconductor material grown on the metal nanoparticle seeds. Gold and cobalt‐platinum nanoparticles are employed as metal seeds, on which CdS or CdSe is grown. Using transmission electron microscopy, absorption spectroscopy (UV–vis), and powder X‐ray diffraction as characterization techniques, a significant influence of chloride ions on the type of nucleation (that is, secondary or primary nucleation) as well as on the shape of the resulting heterostructures is observed. Partially replacing the commonly used cadmium precursor CdO by varying amounts of CdCl₂ opens access to rod‐like, multiarmed, flower‐like, and bullet‐like structures. The results suggest that neither pure CdO nor pure CdCl₂ as precursors but only a mixture of both make these structures obtainable. In this article, the influence of the chloride ion concentration during semiconductor growth on metal seeds is investigated in depth. The morphology of the resulting heterostructures is characterized carefully, and a growth mechanism is suggested. Furthermore, it is shown that this synthetic approach can be transferred to seeds of various metals such as platinum, gold, and cobalt platinum.     

Chloride corrosion of steel fibre reinforcement in cement mortar

This paper presents an experimental study on the corrosion resistance of steel fibres and steel bar reinforcement in cement mortar. The mortar matrix incorporated various amounts of calcium chloride from 2 to 10%, and the rate of corrosion was monitored by the electrode potential method. The structure of the mortar and the steel surfaces were examined by scanning electron microscopy. The results showed that the addition of calcium chloride modified the microstructure of the mortar matrix, both its water absorption capacity and its porosity increased with increasing amounts of calcium chloride. The electric potential measurements showed that while the bar reinforcement displayed corrosion at 2% calcium chloride, the fibres did not indicate any harmful corrosion until the chloride content was 6%. Chloride admixtures added to concrete may thus be less harmful to steel in steel fibre concrete than in reinforced concrete.     

Enhanced Field Emission from a Carbon Nanotube Array Coated with a Hexagonal Boron Nitride Thin Film

A high‐quality field emission electron source made of a highly ordered array of carbon nanotubes (CNTs) coated with a thin film of hexagonal boron nitride (h‐BN) is fabricated using a simple and scalable method. This method offers the benefit of reproducibility, as well as the simplicity, safety, and low cost inherent in using B₂O₃ as the boron precursor. Results measured using h‐BN‐coated CNT arrays are compared with uncoated control arrays. The optimal thickness of the h‐BN film is found to be 3 nm. As a result of the incorporation of h‐BN, the turn‐on field is found to decrease from 4.11 to 1.36 V μm^?1, which can be explained by the significantly lower emission barrier that is achieved due to the negative electron affinity of h‐BN. Meanwhile, the total emission current is observed to increase from 1.6 to 3.7 mA, due to a mechanism that limits the self‐current of any individual emitting tip. This phenomenon also leads to improved emission stability and uniformity. In addition, the lifetime of the arrays is improved as well. The h‐BN‐coated CNT array‐based field emitters proposed in this work may open new paths for the development of future high‐performance vacuum electronic devices.     

Solid-State Interaction of Aluminium Hydroxide with Lithium Salts

The solid-state synthesis of [LiAl₂(OH)₆]Cl · mH₂O at room and elevated temperatures from powdered solid reagents, lithium chloride and gibbsite, is described. The synthesis is performed with the help of different devices including a laboratory mixer, large-scale laboratory arm mixer, and planetary centrifugal mill. The interaction of the components depends on both the dispersity of Al(OH)₃ and the nature of lithium chloride. At the initial stage, the interaction is limited by the rate of lithium chloride diffusion through the layer of the product formed. Activation energy, calculated according to the Valency–Carter equation, is 53 ± 5 kJ/mol.     

CoNi2S4 Nanoparticle/Carbon Nanotube Sponge Cathode with Ultrahigh Capacitance for Highly Compressible Asymmetric Supercapacitor

Compared with other flexible energy‐storage devices, the design and construction of the compressible energy‐storage devices face more difficulty because they must accommodate large strain and shape deformations. In the present work, CoNi₂S₄ nanoparticles/3D porous carbon nanotube (CNT) sponge cathode with highly compressible property and excellent capacitance is prepared by electrodepositing CoNi₂S₄ on CNT sponge, in which CoNi₂S₄ nanoparticles with size among 10–15 nm are uniformly anchored on CNT, causing the cathode to show a high compression property and gives high specific capacitance of 1530 F g⁻¹. Meanwhile, Fe₂O₃/CNT sponge anode with specific capacitance of 460 F g⁻¹ in a prolonged voltage window is also prepared by electrodepositing Fe₂O₃ nanosheets on CNT sponge. An asymmetric supercapacitor (CoNi₂S₄/CNT//Fe₂O₃/CNT) is assembled by using CoNi₂S₄/CNT sponge as positive electrode and Fe₂O₃/CNT sponge as negative electrode in 2 m KOH solution. It exhibits excellent energy density of up to 50 Wh kg⁻¹ at a power density of 847 W kg⁻¹ and excellent cycling stability at high compression. Even at a strain of 85%, about 75% of the initial capacitance is retained after 10 000 consecutive cycles. The CoNi₂S₄/CNT//Fe₂O₃/CNT device is a promising candidate for flexible energy devices due to its excellent compressibility and high energy density.     

Doping Modulated Carbon Nanotube Synapstors for a Spike Neuromorphic Module

A doping‐modulated carbon nanotube (CNT) electronic device, called a “synapstor,” emulates the function of a biological synapse. The CNT synapstor has a field‐effect transistor structure with a random CNT network as its channel. An aluminium oxide (Al₂O₃) film is deposited over half of the CNT channel in the synapstor, converting the covered part of the CNT from p‐type to n‐type, forming a p–n junction in the CNT channel and increasing the Schottky barrier between the n‐type CNT and its metal contact. This scheme significantly improves the postsynaptic current (PSC) from the synapstor, extends the tuning range of the plasticity, and reduces the power consumption of the CNT synapstor. A spike neuromorphic module is fabricated by integrating the CNT synapstors with a Si‐based “soma” circuit. Spike parallel processing, memory, and plasticity functions of the module are demonstrated. The module could potentially be integrated and scaled up to emulate a biological neural network with parallel high‐speed signal processing, low power consumption, memory, and learning capabilities.     

Aligning Solution‐Derived Carbon Nanotube Film with Full Surface Coverage for High‐Performance Electronics Applications

The main challenge for application of solution‐derived carbon nanotubes (CNTs) in high performance field‐effect transistor (FET) is how to align CNTs into an array with high density and full surface coverage. A directional shrinking transfer method is developed to realize high density aligned array based on randomly orientated CNT network film. Through transferring a solution‐derived CNT network film onto a stretched retractable film followed by a shrinking process, alignment degree and density of CNT film increase with the shrinking multiple. The quadruply shrunk CNT films present well alignment, which is identified by the polarized Raman spectroscopy and electrical transport measurements. Based on the high quality and high density aligned CNT array, the fabricated FETs with channel length of 300 nm present ultrahigh performance including on‐state current I_on of 290 µA µm^?1 (V_ds = ?1.5 V and V_gs = ?2 V) and peak transconductance g_m of 150 µS µm^?1, which are, respectively, among the highest corresponding values in the reported CNT array FETs. High quality and high semiconducting purity CNT arrays with high density and full coverage obtained through this method promote the development of high performance CNT‐based electronics.     

Monodisperse CNT Microspheres for High Permeability and Efficiency Flow‐Through Filtration Applications

Carbon nanotube (CNT)‐based filters have the potential to revolutionize water treatment because of their high capacity and fast kinetics in sorption of organic, inorganic, and biological pollutants. To date, CNT filters either rely on CNTs dispersed in liquids, which are difficult to recover and cause safety concerns, or on CNT buckypaper, which offers high efficiency, but suffers from an intrinsic trade‐off between filter permeability and capacity. Here, a new approach is presented that bypasses this trade‐off and achieves buckypaper‐like efficiency combined with filter‐column‐like permeability and capacity. For this, CNTs are first assembled into porous microspheres and then are packed into microfluidic column filters. These microcolumns exhibit large flow‐through filtration efficiencies, while maintaining membrane permeabilities an order of magnitude larger then CNT buckypaper and specific permeabilities double that of activated carbon for similar flowrates (232 000 L m^?2 h^?1 bar^?1, 1.23 × 10^?12 m²). Moreover, in a test to remove sodium dodecyl sulfate (SDS) from water, these microstructured CNT columns outperform activated carbon columns. This improved filtration efficiency and permeability is an important step toward a broader implementation of CNT‐based filtration devices.     

2D MoS2 Neuromorphic Devices for Brain‐Like Computational Systems

Hardware implementation of artificial synapses/neurons with 2D solid‐state devices is of great significance for nanoscale brain‐like computational systems. Here, 2D MoS₂ synaptic/neuronal transistors are fabricated by using poly(vinyl alcohol) as the laterally coupled, proton‐conducting electrolytes. Fundamental synaptic functions, such as an excitatory postsynaptic current, paired‐pulse facilitation, and a dynamic filter for information transmission of biological synapse, are successfully emulated. Most importantly, with multiple input gates and one modulatory gate, spiking‐dependent logic operation/modulation, multiplicative neural coding, and neuronal gain modulation are also experimentally demonstrated. The results indicate that the intriguing 2D MoS₂ transistors are also very promising for the next‐generation of nanoscale neuromorphic device applications.     

Cation‐Induced Stabilization and Denaturation of DNA Origami Nanostructures in Urea and Guanidinium Chloride

The stability of DNA origami nanostructures under various environmental conditions constitutes an important issue in numerous applications, including drug delivery, molecular sensing, and single‐molecule biophysics. Here, the effect of Na⁺ and Mg²⁺ concentrations on DNA origami stability is investigated in the presence of urea and guanidinium chloride (GdmCl), two strong denaturants commonly employed in protein folding studies. While increasing concentrations of both cations stabilize the DNA origami nanostructures against urea denaturation, they are found to promote DNA origami denaturation by GdmCl. These inverse behaviors are rationalized by a salting‐out of Gdm⁺ to the hydrophobic DNA base stack. The effect of cation‐induced DNA origami denaturation by GdmCl deserves consideration in the design of single‐molecule studies and may potentially be exploited in future applications such as selective denaturation for purification purposes.     

Carbon Nanotubes for Cold Electron Sources

Technological advances in the field of microelectronic fabrication techniques have triggered a great interest in vacuum microelectronics. In contrast to solid‐state microelectronics, which entails scattering‐dominated electron transport in semiconducting solids, vacuum microelectronics relies on the scattering‐free, ballistic motion of electrons in vacuum. Since the first international conference on vacuum microelectronics substantial progress in this field has been made. The first technological devices using micrometer‐sized electron emitting structures are currently being commercialized. Field‐emission flat‐panel displays (FED) seem to be an especially promising competitor to LCD displays. Today there is only one mature technology for producing micro‐gated field‐emission arrays: the Spindt metal‐tip process. The drawbacks of this technology are expensive production, critical lifetime in vacuum, and high operating voltage. Carbon nanotubes (CNT) can be regarded as the potential second‐generation technology to the Spindt metal micro‐tip. In this review we show that the field emission (FE) behavior of CNT can be accurately described by Fowler–Nordheim tunneling and that the field‐enhancement factor β is the most prominent factor. Therefore the FE properties of a CNT thin film can be understood in terms of local field enhancement β(x,y), which can be determined with scanning anode field emission microscopy (SAFEM). To characterize the FE properties of an ensemble of electron emitters we used a statistical approach (as for thin film emitters), where f(β)dβ gives the number of emitters on a unit area with field‐enhancement factors within the interval [β,β + dβ]. We show that the field‐enhancement distribution function f(β) gives an almost complete characterization of the FE properties.     

Single‐Carbon‐Nanotube Manipulations and Devices Based on Macroscale Anthracene Flakes

Because of the outstanding mechanical and electrical properties of carbon nanotubes (CNTs), a CNT‐based torsion pendulum is demonstrated to show great potential in nano‐electromechanical systems. It is also expected to achieve various manipulations for further characterization and increase device sensitivity using ultrlong CNTs and macroscale moving parts. However, the reported top‐down method limits the CNT performance and device size by introducing inevitable contamination and destruction, which greatly hinders the development of single‐molecule devices. Here, a bottom‐up method is introduced to fabricate heterostructures of anthracene flakes (AFs) and suspended CNTs, providing a nondamaging CNT mechanical measurement before further applications, especially for the twisting behavior, and providing a controllable and clean transfer method to fabricate CNT‐based electrical devices under ambient conditions. Based on the unique geometry of CNT/AF heterostructures, various complex manipulations of single‐CNT devices are conducted to investigate CNT mechanical properties and prompt novel applications of similar structures in nanotechnology. The AF‐decorated CNTs show high Young's modulus (≈1 TPa) and tensile strength (≈100 GPa), and can be considered as the finest and strongest torsional springs. CNT‐based torsion balance enables to measure fN‐level forces and the torsional spring constant is two orders of magnitude lower than previously reported values.     

Single‐Atom Nanozyme Based on Nanoengineered Fe–N–C Catalyst with Superior Peroxidase‐Like Activity for Ultrasensitive Bioassays

Single‐atom catalysts are becoming a hot research topic owing to their unique characteristics of maximum specific activity and atomic utilization. Herein, a new single‐atom nanozyme (SAN) based on single Fe atoms anchored on N‐doped carbons supported on carbon nanotube (CNT/FeNC) is proposed. The CNT/FeNC with robust atomic Fe–N_x moieties is synthesised, showing superior peroxidase‐like activity. Furthermore, the CNT/FeNC is used as the signal element in a series of paper‐based bioassays for ultrasensitive detection of H₂O₂, glucose, and ascorbic acid. The SAN provides a new type of signal element for developing various biosensing techniques.     

Efficient and Stable Solid‐State Dye‐Sensitized Solar Cells Based on a High‐Molar‐Extinction‐Coefficient Sensitizer

The high‐molar‐extinction‐coefficient heteroleptic ruthenium dye, cis‐Ru (4,4′‐bis(5‐octylthieno[3,2‐b] thiophen‐2‐yl)‐2,2′‐bipyridine) (4,4′‐dicarboxyl‐2,2′‐bipyridine) (NCS)₂, exhibits an AM 1.5 solar (100 mW cm^?2)‐to‐electric power‐conversion efficiency of 4.6% in a solid‐state dye‐sensitized solar cell (SSDSC) with 2,2′, 7,7′‐tetrakis‐(N,N‐di‐p‐methoxyphenylamine)9,9′‐spirobifluorene (spiro‐MeOTAD) as the organic hole‐transporting material. These SSDSC devices exhibit good durability during accelerated tests under visible‐light soaking for 1000 h at 60 °C. This demonstration elucidates a class of photovoltaic devices with potential for stable and low‐cost power generation. The electron recombination dynamics and charge collection that take place at the dye‐sensitized heterojunction are studied by means of impedance and transient photovoltage decay techniques.     

Development and gamma scintigraphy evaluation of gastro retentive calcium ion-based oral formulation: an innovative approach for the management of gastro-esophageal reflux disease (GERD)

Calcium chloride is an essential calcium channel agonist which plays an important role in the contraction of muscles by triggering calcium channel. First time hypothesized about its role in the treatment of GER (gastro-esophageal reflux) and vomiting disorder due to its local action. There are two objectives covered in this study as first, the development and optimization of floating formulation of calcium chloride and another objective was to evaluate optimized formulation through gamma scintigraphy in human subjects. Gastro retentive formulation of calcium chloride was prepared by direct compression method. Thirteen tablet formulations were designed with the help of sodium chloride, HPMC-K4M, and carbopol-934 along with effervescing agent sodium bicarbonate and citric acid. Formulation (F8) fitted best for Korsmeyer–Peppas equation with an R² value of 0.993. The optimized formulation was radiolabelled with ^99mTc-99?m pertechnetate for its evaluation by gamma scintigraphy. Gastric retention (6?h) was evaluated by gamma scintigraphy in healthy human subjects and efficacy of present formulation confirmed in GER positive human subjects. Gamma scintigraphy results indicated its usefulness in order to manage GERD. Stability studies of the developed formulation were carried out as per ICH guidelines for region IV and found out to be stable for 24?months.     

多因素耦合作用下混凝土氯盐侵蚀模糊网络评估模型

单位时间内通过混凝土结构的总电荷量是反映混凝土结构氯离子渗透能力的一个重要指标。针对传统经验公式法预测了氯离子总电荷量的不足,建立了一个模糊-神经网络模型以预测氯离子总电荷量。此模型能同时考虑多种因素及其非线性耦合作用,方便易行、通用性好,较之其它神经网络具有运算速度快、不容易陷入局部最优、训练效果好的特点。训练样本训练后的结果表明,该模型具有较高的准确度,能可靠预测氯离子总电荷量,准确评价混凝土结构的抗氯盐侵蚀能力,为实际工程的耐久性设计和评价提供依据。