碳纳米管纱作为填料应用于硝基芳烃污水处理（英文）

碳纳米管纱(CNTY)因具有优异的力学强度、化学稳定性、热稳定性和高比表面积而成为去除废水中有机污染物的潜在材料。本文将CNTY用于含2,4-二硝基甲苯(DNT)的污水处理。CNTY对DNT的吸附能力与文献报道值作对比研究,同时探讨吸附动力学。采用SEM-EDX、HRTEM、Raman与XPS表征CNTY吸附DNT前后的尺寸、表面形貌及表面化学。结果表明,经CNTY对DNT污水处理后的水质达到实验室无离子水级纯度。CNTY对DNT吸附符合Freundlich吸附等温线,Freundlich参数由K/nF为55.0 mg/g(L/mg)1,指数1/n为0.737得到,表明其比活性炭吸附性弱,但更易再生。CNTY比活性炭的吸附性速率更快,遵循拟二级动力学模型。CNTY吸附DNT引起D、G常偏移,归因于CNTs与DNT间电子受体和供体效应。

声波激励的超小型纳机电系统磁电天线

当前的小型天线依赖于电磁波的谐振,因此天线的尺寸与电磁波波长相关。典型的天线尺寸大于波长的1/10,而进一步缩小天线尺寸在近十年来都是一个公开的挑战。介绍一种通过悬浮铁氧/压电薄膜异质结构的声波激励纳机械磁电天线。这种磁电天线通过其在声波谐振频率处的磁电效应接收和发射电磁波。磁电天线中的体声波激发铁磁薄膜的磁化振荡,产生电磁波的辐射;反之,天线感应电磁波的磁场,得到压电电压输出。这种磁电天线(尺寸仅为波长的千分之一)比现有小型天线的尺寸小1到2个数量级,但性能却没有降低,在便携式无线通信系统中具有很大的应用潜力。

Recent Advances in Hard, Tough, and Low Friction Nanocomposite Coatings

Nanocomposite coatings demonstrate improved friction and wear responses under severe sliding conditions in extreme environments. This paper provides a review how thin film multilayers and nanocomposites result in hard, tough, low-friction coatings. Approaches to couple multilayered and nanocomposite materials with other surface engineering strategies to achieve higher levels of performance in a variety of tribological applications are also discussed. Encapsulating lubricious phases in hard nanocomposite matri- ces is one approach that is discussed in detail. Results from state-of-the-art ＂chameleon＂ nanocomposites that exhibit reversible adaptability to ambient humidity or temperature are presented.

Autonomy in materials research: a case study in carbon nanotube growth

Advances in materials are an important contributor to our technological progress,and yet the process of materials discovery and development itself is slow.Our current research process is human-centred,where human researchers design,conduct,analyse and interpret experiments,and then decide what to do next.We have built an Autonomous Research System(ARES)—an autonomous research robot capable of first-of-its-kind closed-loop iterative materials experimentation.ARES exploits advances in autonomous robotics,artificial intelligence,data sciences,and high-throughput and in situ techniques,and is able to design,execute and analyse its own experiments orders of magnitude faster than current research methods.We applied ARES to study the synthesis of singlewalled carbon nanotubes,and show that it successfully learned to grow them at targeted growth rates.ARES has broad implications for the future roles of humans and autonomous research robots,and for human-machine partnering.We believe autonomous research robots like ARES constitute a disruptive advance in our ability to understand and develop complex materials at an unprecedented rate.

The joint automated repository for various integrated simulations (JARVIS) for data-driven materials design

The Joint Automated Repository for Various Integrated Simulations(JARVIS)is an integrated infrastructure to accelerate materials discovery and design using density functional theory(DFT),classical force-fields(FF),and machine learning(ML)techniques.JARVIS is motivated by the Materials Genome Initiative(MGI)principles of developing open-access databases and tools to reduce the cost and development time of materials discovery,optimization,and deployment.

Charge transfer of carbon nanomaterials for efficient metal‐free electrocatalysis

Recently,carbon-based metal-free electrocatalysts(C‐MFECs)have drawn considerable research attention because of their attractive physicochemical characteristics,cost-effectiveness,and ability to convert and store energy efficiently.Efficient intramolecular charge transfer among different parts of the carbon electrocatalyst and/or intermolecular charge transfer between elec-trocatalyst and electrolyte dictate the ultimate energy conversion performance.Experimental results and theoretical analyses have demonstrated that rational design of metal-free carbon nanomaterials,coupled with proper in-tramolecular charge transfer through heteroatom doping,incorporation of Stone-Wales defects,and/or intermolecular charge transfer through adsorp-tion of appropriate molecules/moieties,can promote efficient electrocatalysis.In this article,we will first provide the related theoretical principles and then present an overview on the rational design and development of C-MFECs for efficient charge transfer,followed by elucidating charge-transfer processes for different electrocatalytic reactions related to renewable energy conversion and environmental remediation technologies.Finally,the current challenges and future perspectives in this exciting field will be discussed.

Atomic and electronic basis for the serrations of refractory high-entropy alloys

Refractory high-entropy alloys present attractive mechanical properties,i.e.,high yield strength and fracture toughness,making them potential candidates for structural applications.Understandings of atomic and electronic interactions are important to reveal the origins for the formation of high-entropy alloys and their structure−dominated mechanical properties,thus enabling the development of a predictive approach for rapidly designing advanced materials.Here,we report the atomic and electronic basis for the valence−electron-concentration-categorized principles and the observed serration behavior in high-entropy alloys and highentropy metallic glass,including MoNbTaW,MoNbVW,MoTaVW,HfNbTiZr,and Vitreloy-1 MG(Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(22.5)).We find that the yield strengths of high-entropy alloys and high-entropy metallic glass are a power-law function of the electron-work function,which is dominated by local atomic arrangements.Further,a reliance on the bonding-charge density provides a groundbreaking insight into the nature of loosely bonded spots in materials.The presence of strongly bonded clusters and weakly bonded glue atoms imply a serrated deformation of high-entropy alloys,resulting in intermittent avalanches of defects movement.

Adhesive free,conformable and washable carbon nanotube fabric electrodes for biosensing

Skin-mounted wearable electronics are attractive for continuous health monitoring and human-machine interfacing.The commonly used pre-gelled rigid and bulky electrodes cause discomfort and are unsuitable for continuous long-term monitoring applications.Here,we design carbon nanotubes(CNTs)-based electrodes that can be fabricated using different textile manufacturing processes.We propose woven and braided electrode design using CNTs wrapped textile yarns which are highly conformable to skin and measure a high-fidelity electrocardiography(ECG)signal.The skin-electrode impedance analysis revealed size-dependent behavior.To demonstrate outstanding wearability,we designed a seamless knit electrode that can be worn as a bracelet.The designed CNT-based dry electrodes demonstrated record high signal-to-noise ratios and were very stable against motion artifacts.The durability test of the electrodes exhibited robustness to laundering and practicality for reusable and sustainable applications.

Design of refractory multi-principal-element alloys for high-temperature applications

Refractory multi-principal-element alloys(RMPEAs)exhibit high specific strength at elevated temperatures(T).However,current RMPEAs lack a balance of room-temperature(RT)ductility,high-T strength,and high-T creep resistance.Using density-functional theory methods,we scanned composition space using four criteria:(1)formation energies for operational stability:-150<E_(f)≤+70 meV per atom;(2)higher strength found via interstitial electron density with Young’s moduli E>250 GPa;(3)inverse Pugh ratio for ductility:G/B<0.57;and(4)high melting points:T_(m)>2500°C.Using rapid bulk alloy synthesis and characterization,we validated theory and down-selected promising alloy compositions and discovered Mo72.3W12.8Ta10.0Ti2.5Zr2.5 having well-balanced RT and high-T mechanical properties.This alloy has comparable high-T compressive strength to well-known MoNbTaW but is more ductile and more creep resistant.It is also superior to a commercial Mo-based refractory alloy and a nickel-based superalloy(Haynes-282)with improved high-T tensile strength and creep resistance.

Functionalization of carbon nanotube yarn by acid treatment

Carbon nanotube(CNT)yarn was functionalized using sulfuric and nitric acid solutions in 3:1 volumetric ratio.Successful functionalization of CNT yarn with carboxyl and hydroxyl groups(e.g.,COOH,COO–,OH,etc.)was confirmed by attenuated total reflectance spectroscopy.X-ray diffraction revealed no significant change to the atomic in-plane alignment in the CNTs;however,the coherent length along the diameter was significantly reduced during functionalization.A morphology change of wavy extensions protruding from the surface was observed after the functionalization treatment.The force required to fracture the yarn remained the same after the functionalization process;however,the linear density was increased(310%).The increase in linear density after functionalization reduced the tenacity.However,the resistivity density product of the CNT yarn was reduced significantly(234%)after functionalization.

Comparison of magnetic properties of DNA-cetyltrimethyl ammonium complex with those of natural DNA

We prepared the DNA-cetyltrimethyl ammonium complex, as well as the same complex intercalated with stable organic free radicals, and studied their magnetic properties by electron magnetic resonance (EMR) spectroscopy and by measuring the magnetization on a superconducting quantum interference device (SQUID). The UV-vis and CD spectra of DNA-quaternary alkyl ammonium complex (DNA--Q+) in organic solvent clearly demonstrated that it retained the double helical B-form conformation. The interhelical spacing of double strand DNA (dsDNA) increased when the counter ions (Na+) of phosphate groups of the natural DNA were replaced with the long alkyl quaternary ammonium groups. The inter-helical distance of DNA-cetyltrimethyl ammonium (CTMA) was 39.1  as confirmed by X-ray diffractometry. In general, the magnetization of the DNA-CTMA complex solid was found to be significantly lower than that of natural DNA. Moreover, intercalation of the complex with stable organic free radicals did not improve magnetization, which again was in marked contrast to natural DNA. EMR spectroscopic behavior of the complex in the solid state also was quite different from that of natural DNA: The unique broad EMR signal of natural DNA in the low field region with g-value greater than 10 disappeared in the DNA-CTMA complex.

The lattice Boltzmann Peierls Callaway equation for mesoscopic thermal transport modeling

The lattice Boltzmann Peierls Callaway(LBPC)method is a recent development of the versatile lattice Boltzmann formalism aimed at a numerical experiment on mesoscale thermal transport in a multiphase phonon gas.Two aspects of mesoscopic thermal trans-port are discussed:the finite phonon mean free path and the interface thermal resistance.Based on the phonon momentum screening length measured in the LBPC computa-tional apparatus,the validity of the Umklapp collision relaxation time in the Callaway collision operator is examined quantitatively.The discrete nature of the spatio-temporal domain in the LBPC method,along with the linear approximation of the exponential screening mechanism in the Callaway operator,reveals a large discrepancy between the effective phonon mean free path and the analytic phonon mean free path when the relaxation time is small.The link bounce back interface phonon collision rule is used to realize the interface thermal resistance between phonon gases with dissimilar dispersion relations.Consistent with the Callaway collision operator for the bulk phonon dynam-ics,the interface phonon collision process is regarded as a linear relaxation mechanism toward the local pseudo-equilibrium phonon distribution uniquely defined by the energy conservation principle.The interface thermal resistance is linearly proportional to the relaxation time of the proposed phonon interface collision rule.

Advanced machine learning decision policies for diameter control of carbon nanotubes

The diameters of single-walled carbon nanotubes(SWCNTs)are directly related to their electronic properties,making diameter control highly desirable for a number of applications.Here we utilized a machine learning planner based on the Expected Improvement decision policy that mapped regions where growth was feasible vs.not feasible and further optimized synthesis conditions to selectively grow SWCNTs within a narrow diameter range.We maximized two ranges corresponding to Raman radial breathing mode frequencies around 265 and 225 cm^(−1)(SWCNT diameters around 0.92 and 1.06 nm,respectively),and our planner found optimal synthesis conditions within a hundred experiments.Extensive post-growth characterization showed high selectivity in the optimized growth experiments compared to the unoptimized growth experiments.Remarkably,our planner revealed significantly different synthesis conditions for maximizing the two diameter ranges in spite of their relative closeness.Our study shows the promise for machine learning-driven diameter optimization and paves the way towards chirality-controlled SWCNT growth.