Printable Aligned Single-Walled Carbon Nanotube Film with Outstanding Thermal Conductivity and Electromagnetic Interference Shielding Performance

Ultrathin,lightweight,and flexible aligned single-walled carbon nanotube(SWCNT)films are fabricated by a facile,environmentally friendly,and scalable printing methodology.The aligned pattern and outstanding intrinsic properties render“metal-like”thermal conductivity of the SWCNT films,as well as excellent mechanical strength,flexibility,and hydrophobicity.Further,the aligned cellular microstructure promotes the electromagnetic interference(EMI)shielding ability of the SWCNTs,leading to excellent shielding effectiveness(SE)of~39 to 90 dB despite a density of only~0.6 g cm^(−3) at thicknesses of merely 1.5-24μm,respectively.An ultrahigh thickness-specific SE of 25693 dB mm^(−1) and an unprecedented normalized specific SE of 428222 dB cm^(2)g^(−1) are accomplished by the freestanding SWCNT films,significantly surpassing previously reported shielding materials.In addition to an EMI SE greater than 54 dB in an ultra-broadband frequency range of around 400 GHz,the films demonstrate excellent EMI shielding stability and reliability when subjected to mechanical deformation,chemical(acid/alkali/organic solvent)corrosion,and high-/low-temperature environments.The novel printed SWCNT films offer significant potential for practical applications in the aerospace,defense,precision components,and smart wearable electronics industries.

SEGMENTATION AND CORRELATION OF OPTICAL COHERENCE TOMOGRAPHY AND X-RAY IMAGES FOR BREAST CANCER DIAGNOSTICS

Pre-operative X ray mammography and int raoperative X-ray specimen radiography are routinely used to identify breast cancer pathology.Recent advances in optical coherence tomography(OCT)have enabled its 1use for the intraoperative assessment of surgical margins during breast cancer surgery.While each modality offers distinct contrast of normal and pathological features,there is an essential need to correlate image based features between the two modalities to take adv antage of the diagnostic capabilities of each technique.We compare OCT to X-ray images of resected human breast tissue and correlate different tissue features between modalities for future use in real-tine intraoperative OCT imaging.X ray imaging(specimen radiography)is currently used during surgical breast cancer procedures to verify tumor margins,but cannot image tissue in situ.OCT has the potential to solve this problem by providing intrao-perative imaging of the resected specimen as well as the in situ tumor cavity.OCT and micro-CT(X-ray)images are automatically segmented using different computational approaches,and quantitatively compared to determine the ability of these algorithms to automat ically differentiate regions of adipose tissue from tumor.Furthermore,two-dimensional(2D)and three-dimensional(3D)results are compared.These correlations,combined with real-time intraoperative OCT,have the potential to identify possible regions of tumor within breast tissue which correlate to tumor regions identified previously on X-ray imaging(mammography or specimen radiography).

MXene ink hosting zinc anode for high performance aqueous zinc metal batteries

Despite the safety,low cost,and high theoretical capacity(820 mA h g^(-1))of Zn metal anodes,the practical application of aqueous Zn metal batteries remains a critical challenge due to the Zn dendrite growth,corrosion,and hydrogen evolution reaction.Herein,we demonstrate the MXene ink hosting Zn metal anodes(MX@Zn)for high-performance and patternable Zn metal full batteries.The as-designed MX@Zn electrode is more facile and reversible than bare Zn and CC@Zn,as verified by better cyclic stability and lower overpotentials of symmetric cells with the plating capacity of 0.05 mA h cm^(-2)at 0.1 m A cm^(-2)and of 1 m A h cm^(-2)at 1 m A cm^(-2).The MX@Zn|MnO_(2)full cells deliver a high specific capacity of 281.9 m A h g^(-1),91.5%of the theoretical capacity,achieving 50%capacity retention from 60 mA g^(-1)to 300 mA g^(-1)and 79.7%of initial capacity after 200 cycles.Moreover,the patterned devices based on the MX@Zn electrode achieve high energy and power densities of 348.57 Wh kg^(-1)and 1556 W kg^(-1),respectively,along with a capacity retention of 64%and Coulombic efficiency of 99%over 500 cycles.The high performance of MX@Zn is attributed to the high electrical conductivity and hydrophilicity of MXene and rapid ion diffusion through the 3D interconnected porous channels.

FC-DIRECTED ANTIBODY CONJUGATION OF MAGNETIC NANOPARTICLES FOR ENHANCED MOLECULAR TARGETING

In this study, we report the fabrication of engineered iron oxide magnetic nanoparticles (MNPs)functionalized with anti-human epidermal growth factor receptor type 2 (HER2) antibody totarget the tumor antigen HER2. The Fc-directed conjugation of antibodies to the MNPs aidstheir efficient immunospecific targeting through free Fab portions. The directional specificity ofconjugation was verified on a macrophage cell line. Immunofluorescence studies on macrophagestreated with functionalized MNPs and free anti-HER2 antibody revealed that the antibodymolecules bind to the MNPs predominantly through their Fc portion. Different cell lines with different HER2 expression levels were used to test the specificity of our functionalized nanoprobe formolecular targeting applications. The results of cell line targeting demonstrate that these engineered MNPs are able to differentiate between cell lines with different levels of HER2 expression.

Video-rate multimodal multiphoton imaging and three-dimensional characterization of cellular dynamics in wounded skin

To date,numerous studies have been performed to elucidate the complex cellular dynamics in skin diseases,but few have attempted to characterize these cellular events under conditions similar to the native environment.To address this challenge,a three-dimensional(3D)multimodal analysis platform was developed for characterizing in vivo cellular dynamics in skin,which was then utilized to process in vivo wound healing data to demonstrate its applicability.Special attention is focused on in vivo biological parameters that are difficult to study with ex vivo analysis,including 3D cell tracking and techniques to connect biological information obtained from different imaging modalities.These results here open new possibilities for evaluating 3D cellular dynamics in vivo,and can potentially provide new tools for characterizing the skin microenvironment and pathologies in the future.

Nonlinear optical imaging by detection with optical parametric amplification(invited paper)

Nonlinear optical imaging is a versatile tool that has been proven to be exceptionally useful in various research fields.However,due to the use of photomultiplier tubes(PMTs),the wide application of nonlinear optical imaging is limited by the incapability of imaging under am-bient light.In this paper,we propose and demonstrate a new optical imaging detection method based on optical parametric amplification(OPA).As a nonlinear optical process,OPA in-trinsically rejects ambient light photons by coherence gating.Periodical poled lithium niobate(PPLN)crystals are used in this study as the media for OPA.Compared to bulk nonlinear optical crystals,PPLN crystals support the generation of OPA signal with lower pump power.Therefore,this characteristic of PPLN crystals is particularly beneficial when using high-repetition-rate lasers,which facilitate high-speed optical signal detection,such as in spec-troscopy and imaging.A PPLN-based OPA system was built to amplify the emitted imaging signal from second harmonic generation(SHG)and coherent anti-Stokes Raman scattering(CARS)microscopy imaging,and the amplified optical signal was strong enough to be detected by a biased photodiode under ordinary room light conditions.With OPA detection,ambient-light-on SHG and CARS imaging becomes possible,and achieves a similar result as PMT detection under strictly dark environments.These results demonstrate that OPA can be used as a substitute for PMTs in nonlinear optical imaging to adapt it to various applications with complex.light ing conditions.

Random Networks and Aligned Arrays of Single-Walled Carbon Nanotubes for Electronic Device Applications

Singled-walled carbon nanotubes(SWNTs),in the form of ultrathin fi lms of random networks,aligned arrays,or anything in between,provide an unusual type of electronic material that can be integrated into circuits in a conventional,scalable fashion.The electrical,mechanical,and optical properties of such fi lms can,in certain cases,approach the remarkable characteristics of the individual SWNTs,thereby making them attractive for applications in electronics,sensors,and other systems.This review discusses the synthesis and assembly of SWNTs into thin film architectures of various types and provides examples of their use in digital electronic circuits with levels of integration approaching 100 transistors and in analog radio frequency(RF)systems with operating frequencies up to several gigahertz,including transistor radios in which SWNT transistors provide all of the active functionality.The results represent important steps in the development of an SWNT-based electronics technology that could fi nd utility in areas such as fl exible electronics,RF analog devices and others that might complement the capabilities of established systems.

Accelerated design and discovery of perovskites with high conductivity for energy applications through machine learning

We use machine learning tools for the design and discovery of ABO3-type perovskite oxides for various energy applications,using over 7000 data points from the literature.We demonstrate a robust learning framework for efficient and accurate prediction of total conductivity of perovskites and their classification based on the type of charge carrier at different conditions of temperature and environment.After evaluating a set of>100 features,we identify average ionic radius,minimum electronegativity,minimum atomic mass,minimum formation energy of oxides for all B-site,and B-site dopant ions of the perovskite as the crucial and relevant predictors for determining conductivity and the type of charge carriers.The models are validated by predicting the conductivity of compounds absent in the training set.We screen 1793 undoped and 95,832 A-site and B-site doped perovskites to report the perovskites with high conductivities,which can be used for different energy applications,depending on the type of the charge carriers.

DYNAMIC OPTICAL COHERENCE ELASTOGRAPHY:A REVIEW

With the development of optical coherence tomography,the application optical coherence elastography(OCE)has gained more and more attention in biomechanics for its unique features including micron-scale resolution,real-time processing,and non-invasive imaging.In this review,one group of OCE techniques,namely dynamic OCE,are introduced and discussed including external dynamic OCE mapping and imaging of ex vivo breast tumor,external dynamic OCE measurement of in vivo human skin,and internal dynamic OCE including acoustomotive OCE and magnetomotive OCE.These techniques overcame some of the major drawbacks of traditional static OCE,and broadened the OCE application fields.Driven by scientific needs to engineer new quantitative methods that utilize the high micron-scale resolution achievable with optics,results of biomechanical properties were obtained from biological tissues.The results suggest potential diagnostic and therapeutic clinical applications.Results from these studies also help our understanding of the relationship between biomechanical variations and functional tissue changes in biological systems.

Distinct mechanisms of FAK mechanoactivation by different extracellular matrix proteins

Introduction Cells can sense and respond to the mechanical microenvironment by converting forces into biochemical signals inside the cells,i.e.mechanotransduction[1-3].Focal adhesions are the major sites of interaction between a cell and its extracellular matrix（ECM）microenvironment,thus outside mechanical signals can be sensed at focal adhesions through transmembrane receptor integrins.In particular,it has been shown that matrix elasticity can control the cell fate[4]by modulating the interactions between ECM proteins and their receptor integrins[5,6].For example,different rigidity of polyacrylamide（PA）gels can lead to different density of ECM ancho-

Computational analysis of spatiotemporal molecular hierarchy in single live cells

Genetically encoded biosensors based on fluorescence resonance energy transfer(FRET)have been widely applied to visualize the molecular activity in live cells with high spatiotemporal resolution.The enormous amount of video images and the complex dynamics of signaling events present tremendous challenges for data analysis and demand the development of intelligent and automated imaging analysis methods specifically envisioned for the studies of live cell imaging.We have developed a general correlative FRET imaging method(CFIM)to quantify the subcellular coupling between an enzymatic activity and a phenotypic response in live cells,e.g.at focal adhesions(FAs).CFIM quantitatively evaluated the cause-effect relation-

Self-assembled microtubular electrodes for on-chip low-voltage electrophoretic manipulation of charged particles and macromolecules

On-chip manipulation of charged particles using electrophoresis or electroosmosis is widely used for many applications,including optofluidic sensing,bioanalysis and macromolecular data storage.We hereby demonstrate a technique for the capture,localization,and release of charged particles and DNA molecules in an aqueous solution using tubular structures enabled by a strain-induced self-rolled-up nanomembrane(S-RuM)platform.Cuffed-in 3D electrodes that are embedded in cylindrical S-RuM structures and biased by a constant DC voltage are used to provide a uniform electrical field inside the microtubular devices.Efficient charged-particle manipulation is achieved at a bias voltage of<2-4 V,which is~3 orders of magnitude lower than the required potential in traditional DC electrophoretic devices.Furthermore,Poisson-Boltzmann multiphysics simulation validates the feasibility and advantage of our microtubular charge manipulation devices over planar and other 3D variations of microfluidic devices.This work lays the foundation for on-chip DNA manipulation for data storage applications.

Three-Dimensional Shear Wave Elastography Using a 2D Row Column Addressing(RCA)Array

Objective.To develop a 3D shear wave elastography(SWE)technique using a 2D row column addressing(RCA)array,with either external vibration or acoustic radiation force(ARF)as the shear wave source.Impact Statement.The proposed method paves the way for clinical translation of 3D SWE based on the 2D RCA,providing a low-cost and high volume rate solution that is compatible with existing clinical systems.Introduction.SWE is an established ultrasound imaging modality that provides a direct and quantitative assessment of tissue stiffness,which is significant for a wide range of clinical applications including cancer and liver fibrosis.SWE requires high frame rate imaging for robust shear wave tracking.Due to the technical challenges associated with high volume rate imaging in 3D,current SWE techniques are typically confined to 2D.Advancing SWE from 2D to 3D is significant because of the heterogeneous nature of tissue,which demands 3D imaging for accurate and comprehensive evaluation.Methods.A 3D SWE method using a RCA array was developed with a volume rate up to 2000 Hz.The performance of the proposed method was systematically evaluated on tissue-mimicking elasticity phantoms and in an in vivo case study.Results.3D shear wave motion induced by either external vibration or ARF was successfully detected with the proposed method.Robust 3D shear wave speed maps were reconstructed for phantoms and in vivo.Conclusion.The high volume rate 3D imaging provided by the 2D RCA array provides a robust and practical solution for 3D SWE with a clear pathway for future clinical translation.

Direct laser writing of volumetric gradient index lenses and waveguides

Direct laser writing(DLW)has been shown to render 3D polymeric optical components,including lenses,beam expanders,and mirrors,with submicrometer precision.However,these printed structures are limited to the refractive index and dispersive properties of the photopolymer.Here,we present the subsurface controllable refractive index via beam exposure(SCRIBE)method,a lithographic approach that enables the tuning of the refractive index over a range of greater than 0.3 by performing DLW inside photoresist-filled nanoporous silicon and silica scaffolds.Adjusting the laser exposure during printing enables 3D submicron control of the polymer infilling and thus the refractive index and chromatic dispersion.Combining SCRIBE’s unprecedented index range and 3D writing accuracy has realized the world’s smallest(15μm diameter)spherical Luneburg lens operating at visible wavelengths.SCRIBE’s ability to tune the chromatic dispersion alongside the refractive index was leveraged to render achromatic doublets in a single printing step,eliminating the need for multiple photoresins and writing sequences.SCRIBE also has the potential to form multicomponent optics by cascading optical elements within a scaffold.As a demonstration,stacked focusing structures that generate photonic nanojets were fabricated inside porous silicon.Finally,an all-pass ring resonator was coupled to a subsurface 3D waveguide.The measured quality factor of 4600 at 1550 nm suggests the possibility of compact photonic systems with optical interconnects that traverse multiple planes.SCRIBE is uniquely suited for constructing such photonic integrated circuits due to its ability to integrate multiple optical components,including lenses and waveguides,without additional printed supports.

MECHANICS ANALYSIS OF TWO-DIMENSIONALLY PRESTRAINED ELASTOMERIC THIN FILM FOR STRETCHABLE ELECTRONICS

Various methods have been developed to fabricate highly stretchable electronics. Recent studies show that over 100% two dimensional stretchability can be achieved by mesh structure of brittle functioning devices interconnected with serpentine bridges. Kim et al show that pressing down an inflated elastomeric thin film during transfer printing introduces two di- mensional prestrain, and therefore further improves the system stretchability. This paper gives a theoretical study of this process, through both analytical and numerical approaches. Simple analytical solutions are obtained for meridional and circumferential strains in the thin film, as well as the maximum strain in device islands, which all agree reasonably well with finite element analysis.

Enhanced thermoelectric performance of two dimensional MS2(M=Mo,W)through phase engineering

The potential application of monolayer MS2(M?Mo,W)as thermoelectric material has been widely studied since the first report of successful fabrication.However,their performances are hindered by the considerable band gap and the large lattice thermal conductivity in the pristine 2H phase.Recent discoveries of polymorphism in MS2s provide new opportunities for materials engineering.In this work,phonon and electron transport properties of both 2H and 1T0 phases were investigated by first-principle calculations.It is found that upon the phase transition from 2H to 1T0 in MS2,the electron transport is greatly enhanced,while the lattice thermal conductivity is reduced by several times.These features lead to a significant enhancement of power factor by one order of magnitude in MoS2 and by three times in WS2.Meanwhile,the figure of merit can reach up to 0.33 for 1T0eMoS2 and 0.68 for 1T0eWS2 at low temperature.These findings indicate that monolayer MS2 in the 1T0 phase can be promising materials for thermoelectric devices application.Meanwhile,this work demonstrates that phase engineering techniques can bring in one important control parameter in materials design.

Understanding the “Horizontal Dimension” of Molecular Evolution to Annotate, Classify, and Discover Proteins with Functional Domains

Protein evolution proceeds by two distinct processes： 1） individual mutation and selection for adaptive mutations and 2） rearrangement of entire domains within proteins into novel combinations, producing new protein families that combine functional properties in ways that previously did not exist. Domain rearrangement poses a challenge to sequence alignment-based search methods, such as BLAST, in predicting homology since the methodology implicitly assumes that related proteins primarily differ from each other by individual mutations. Moreover, there is ample evidence that the evolutionary process has used （and continues to use） domains as building blocks, therefore, it seems fit to utilize computational, domain-based methods to reconstruct that process. A challenge and opportunity for computational biology is how to use knowledge of evolutionary domain recombination to characterize families of proteins whose evolutionary history includes such recombination, to discover novel proteins, and to infer protein-protein interactions. In this paper we review techniques and databases that exploit our growing knowledge of “horizontal” protein evolution, and suggest possible areas of future development. We illustrate the power of the domain-based methods and the possible directions of future development by a case history in progress aiming at facilitating a particular approach to understanding microbial pathogenicity.

Chevron-type graphene nanoribbons with a reduced energy band gap:Solution synthesis,scanning tunneling microscopy and electrical characterization

Graphene nanoribbons(GNRs)attract a growing interest due to their tunable physical properties and promise for device applications.A variety of atomically precise GNRs have recently been synthesized by on-surface and solution approaches.While on-surface GNRs can be conveniently visualized by scanning tunneling microscopy(STM),and their electronic structure can be probed by scanning tunneling spectroscopy(STS),such characterization remains a great challenge for the solution-synthesized GNRs.Here,we report solution synthesis and detailed STM/STS characterization of atomically precise GNRs with a meandering shape that are structurally related to chevron GNRs but have a reduced energy band gap.The ribbons were synthesized by Ni0-mediated Yamamoto polymerization of specially designed molecular precursors using triflates as the leaving groups and oxidative cyclodehydrogenation of the resulting polymers using Scholl reaction.The ribbons were deposited onto III-V semiconducting InAs(110)substrates by a dry contact transfer technique.High-resolution STM/STS characterization not only confirmed the GNR geometry,but also revealed details of electronic structure including energy states,electronic band gap,as well as the spatial distribution of the local density of states.The experimental STS band gap of GNRs is about 2 eV,which is very close to 2.35 eV predicted by the density functional theory simulations with GW correction,indicating a weak screening effect of InAs(110)substrate.Furthermore,several aspects of GNR-InAs(110)substrate interactions were also probed and analyzed,including GNR tunable transparency,alignment to the substrate,and manipulations of GNR position by the STM tip.The weak interaction between the GNRs and the InAs(110)surface makes InAs(110)an ideal substrate for investigating the intrinsic properties of GNRs.Because of the reduced energy band gap of these ribbons,the GNR thin films exhibit appreciably high electrical conductivity and on/off ratios of about 10 in field-effect transistor measurements,suggesting their promise for device applications.

Mechanistic insight into gold nanorod transformation in nanoscale confinement of ZIF-8

Core-shell hybrid nanomaterials have shown new properties and functions that are not attainable by their single counterparts.Nanoscale confinement effect by porous inorganic shells in the hybrid nanostructures plays an important role for chemical transformation of the core nanoparticles.However,metal-organic frameworks(MOFs)have been rarely applied for understanding mechanical insight into such nanoscale phenomena in confinement,although MOFs would provide a variety of properties for the confining environment than other inorganic shells such as silica and zeolite.Here,we examine chemical transformation of a gold nanorod core enclosed by a zeolitic imidazolate framework(ZIF)through chemical etching and regrowth,followed by quantitative analysis in the core dimension and curvature.We find the nanorod core shows template-effective behavior in its morphological transformation.In the etching event,the nanorod core is spherically carved from its tips.The regrowth on the spherically etched core inside the ZIF gives rise toformation of a raspberry-like branched nanostructure in contrast to the growth of an octahedral shape in bulk condition.We attribute the shell-directed regrowth to void space generated at the interfaces between the etched core and the ZIF shell,intercrystalline gaps in mult-domain ZIF shells,and local structural deformation from the acidic reaction conditions.

Fluorescent nanodiamonds for characterization of nonlinear microscopy systems

Characterizing the performance of fluorescence microscopy and nonlinear imaging systems is an essential step required for imaging system optimization and quality control during longitudinal experiments. Emerging multimodal nonlinear imaging techniques require a new generation of microscopy calibration targets that are not susceptible to bleaching and can provide a contrast across the multiple modalities. Here, we present a nanodiamond-based calibration target for microscopy, designed for facilitating reproducible measurements at the object plane. The target is designed to support day-to-day instrumentation development efforts in microscopy laboratories. The images of a phantom contain information about the imaging performance of a microscopy system across multiple spectral windows and modalities. Since fluorescent nanodiamonds are not prone to bleaching, the proposed imaging target can serve as a standard, shelf-stable sample to provide rapid reference measurements for ensuring consistent performance of microscopy systems in microscopy laboratories and imaging facilities.