Tunable Width Research Articles

Strand-Morphology-Based Process Optimization for Extrusion-Based Silicone Additive Manufacturing.

In the silicone material extrusion (MEX) process, product profile error and performance defects are common problems due to changes in strand shape. A process optimization method considering strand morphology, denoted as SMO, which allows adjustment of the strand shape by adjusting process parameters during the printing process is presented. The relation between process parameters (extrusion speed, moving speed, nozzle height, and nozzle radius) and the geometric parameters (strand width and strand height) of the cross-section, as well as the relationship between strand spacing, layer height, and process parameters in no void constraint is discussed and verified. SMO was utilized to produce specimens with tunable strand width and strand height. Tensile tests and profile scans were performed to compare SMO with other methods to verify its feasibility. Specimens fabricated using the SMO method have up to a 7% increase in tensile strength, up to a 10% reduction in processing time, and about a 60% reduction in strand height error over unused ones. The results show that the SMO method with adjustable strand width can effectively balance efficiency and mechanical properties compared to uniform infill, and the SMO method with adjustable strand height can provide higher accuracy compared to uniform strand height. The proposed method is validated and improves the efficiency and accuracy of silicone MEX.

Synthesis of two-dimensional/one-dimensional heterostructures with tunable width

Two-dimensional/one-dimensional (2D/1D) heterostructures as a new type of heterostructure have been studied for their unusual properties and promising applications in electronic and optoelectronic devices. However, the studies of 2D/1D heterostructures are mainly focused on vertical heterostructures, such as MoS2 nanosheet-carbon nanotubes. The research on lateral 2D/1D heterostructures with a tunable width of 1D material is still scarce. In this study, bidirectional flow chemical vapor deposition (CVD) was used to accurately control the width of the WS2/WSe2 (WS2/MoS2) heterostructures by controlling reacting time. WSe2 and MoS2 with different widths were epitaxially grown at the edge of WS2, respectively. Optical microscope, atomic force microscope (AFM), and scanning electron microscope (SEM) images show the morphology and width of the heterostructures. These results show that the width of the heterostructures can be as low as 10 nm by using this method. The interface of the heterostructure is clear and smooth, which is suitable for application. This report offers a new method for the growth of 1D nanowires, and lays the foundation for the future study of the physical and chemical properties of 2D/1D lateral heterostructures.

Magnetically tunable fiber polarization beam splitter

A polarization beam splitter (PBS) based on a magnetic fluid-filled dual-core photonic crystal fiber is characterized. This is the first time that anisotropy of magnetic fluid is applied to the fiber polarization beam splitter. The designed device is able to separate x and y polarization modes completely by applying an external magnetic field. When the length of the device is 9.905 mm (or 16.795 mm), the maximum bandwidth of the effective working wavelength is 26 nm (or 70 nm) and the tunable magnetic field width is approximately 5 Oe (or 165 Oe) corresponding to magnetic field range from 24 to 29 Oe (or 135 to 300 Oe). By tuning the external magnetic field, the proposed beam splitter may be selected to operate in the S, C, and L bands, and the working wavelength bandwidth and center wavelength are tunable.

Atomically-Precise Texturing of Hexagonal Boron Nitride Nanostripes.

Monolayer hexagonal boron nitride (hBN) is attracting considerable attention because of its potential applications in areas such as nano‐ and opto‐electronics, quantum optics and nanomagnetism. However, the implementation of such functional hBN demands precise lateral nanostructuration and integration with other two‐dimensional materials, and hence, novel routes of synthesis beyond exfoliation. Here, a disruptive approach is demonstrated, namely, imprinting the lateral pattern of an atomically stepped one‐dimensional template into a hBN monolayer. Specifically, hBN is epitaxially grown on vicinal Rhodium (Rh) surfaces using a Rh curved crystal for a systematic exploration, which produces a periodically textured, nanostriped hBN carpet that coats Rh(111)‐oriented terraces and lattice‐matched Rh(337) facets with tunable width. The electronic structure reveals a nanoscale periodic modulation of the hBN atomic potential that leads to an effective lateral semiconductor multi‐stripe. The potential of such atomically thin hBN heterostructure for future applications is discussed.

Tunable Porous Electrode Architectures for Enhanced Li-Ion Storage Kinetics in Thick Electrodes

Thick electrodes, although promising toward high-energy battery systems, suffer from restricted lithium-ion transport kinetics due to prolonged diffusion lengths and tortuous transport pathways. Despite the emerging low-tortuosity designs, capacity retention under higher current densities is still limited. Herein, we employ a modified ice-templating method to fabricate low-tortuosity porous electrodes with tunable wall thickness and channel width and systematically investigate the critical impacts of the fine structural parameters on the thick electrode electrochemistry. While the porous electrodes with thick walls show diminished capability under a C-rate larger than 1.5 C, those with thinner walls could maintain ∼70% capacity under 2.5 C. The superior capacity retention is ascribed to the fast diffusion into the thin lamellar walls compared with their thicker counterparts. This study provides deeper insights into structure-affected electrochemistry and opens up new perspective of 3D porous architectural designs for high-energy and high-power electrodes.

Free-space realization of tunable pin-like optical vortex beams

We demonstrate, both analytically and experimentally, free-space pin-like optical vortex beams (POVBs). Such angular-momentum-carrying beams feature tunable peak intensity and undergo robust antidiffracting propagation, realized by judiciously modulating both the amplitude and the phase profile of a standard laser beam. Specifically, they are generated by superimposing a radially symmetric power-law phase on a helical phase structure, which allows the inclusion of an orbital angular momentum term to the POVBs. During propagation in free space, these POVBs initially exhibit autofocusing dynamics, and subsequently their amplitude patterns morph into a high-order Bessel-like profile characterized by a hollow core and an annular main lobe with a constant or tunable width during propagation. In contrast with numerous previous endeavors on Bessel beams, our work represents the first demonstration of long-distance free-space generation of optical vortex “pins” with their peak intensity evolution controlled by the impressed amplitude structure. Both the Poynting vectors and the optical radiation forces associated with these beams are also numerically analyzed, revealing novel properties that may be useful for a wide range of applications.

Three-dimensional Ag2S cubes for switchable multi-wavelength ultrashort pulse application

Three-dimensional (3D) materials are widely used in optoelectronics, thermodynamics and ultrafast fiber lasers because of their excellent nonlinear optical properties. Silver sulfide (Ag2S) is a kind of 3D material with a unique cubic structure and large absorption coefficient. In this paper, a double-balance detection system is used to measure the saturation absorption intensity of Ag2S as 226.6 MW cm−2 and the modulation depth as 13.9%. In the ring fiber laser, Ag2S is used as a saturable absorber (SA) to obtain a stable dual-wavelength mode locking. The center wavelengths of the mode locking are 1536.9 and 1544.5 nm, and the corresponding 3 dB bandwidths are 1.3 and 1.5. nm. By adjusting the polarization controller, a tuning process from two wavelengths to multiple wavelengths is realized, and the tunable width is 13.1 nm. This phenomenon is due to the combined effect of birefringence and nonlinear effects in the cavity. To our knowledge, this is the first report of a multiplexed fiber laser with Ag2S as a SA. The emergence of this result provides a valuable reference information for the multifunctional compact fiber laser, and the formed system can be applied in the fields of fiber sensing, telecommunications and optical communication.

Tunable Damping in Magnetic Nanowires Induced by Chiral Pumping of Spin Waves.

Spin-current and spin-wave-based devices have been considered as promising candidates for next-generation information transport and processing and wave-based computing technologies with low-power consumption. Spin pumping has attracted tremendous attention and has led to interesting phenomena, including the line width broadening, which indicates damping enhancement due to energy dissipation. Recently, chiral spin pumping of spin waves has been experimentally realized and theoretically studied in magnetic nanostructures. Here, we experimentally observe by Brillouin light scattering (BLS) microscopy the line width broadening sensitive to magnetization configuration in a hybrid metal-insulator nanostructure consisting of a Co nanowire grating dipolarly coupled to a planar continuous YIG film, consistent with the results of the measured hysteresis loop. Tunable line width broadening has been confirmed independently by propagating spin-wave spectroscopy, where unidirectional spin waves are detected. Position-dependent BLS measurement unravels an oscillating-like behavior of magnon populations in Co nanowire grating, which might result from the magnon trap effect. These results are thus attractive for reconfigurable nanomagnonics devices.

15‐2: Student Paper: Programmable LTPS‐TFT Gate Driver with Tunable Pulse Width for Adjusting AMOLED Brightness

This paper demonstrates a novel low‐temperature‐poly‐Si thin‐film transistors (LTPS TFTs) gate driver with tunable width for low‐grey level brightness adjustment of active‐matrix organic light‐emitting diode (AMOLED) display. The width of output pulses can be tuned accordingly by changing the number of input pulses, to avoid changing the frequency, duty ratio, or increasing the numbers of the external clock‐lines. The proposed circuit still works well when outputting 10 ms pulse with leakage current above 1.45 nA.

Tunable edge enhancement by higher-order spiral Fresnel incoherent correlation holography system

Tunable edge enhancement can selectively emphasize the edge features of objects. We demonstrate a higher-order spiral Fresnel incoherent correlation holography system to realize isotropic edge enhancement with tunable width. The spatial light modulator is space-division multiplexed by a conventional lens and a spiral lens with a series of higher-order Laguerre–Gaussian phases. The effects of the radial quantum number p and the angular quantum number l on the spatial filtering are theoretically discussed, as well as confirmed by simulations and experiments. Reconstruction images of resolution target, hairs and label-free onion cells all show obvious tunable edge enhancement effects, which makes the edge information easier to be identified. Furthermore, double-edge enhancement is also detected for the first time.

Boron carbon oxyphosphide heterostructured nanodots with phosphate tunable emission for switchable dual detection channels of 6-mercaptopurine assay

The preparation of boron-carbon-oxygen (BCO)-based heterostructure needs commonly high temperature, high pressure and/or auxiliary strong oxidant. And the BCO-based probe for the sensing application is still rare owing to their few active groups, low quantum yield or missing specificity. Exploring BCO-based heterostructured probe via simple routes and application in sensing, therefore, is highly challenging. Herein, we proposed a novel boron-carbon-phosphorus-oxygen (BCPO) nanodot with phosphate tunable near-ultraviolet emission performance and narrow full width at half maximum by a facile, green and gentle synthesis process. The BCPO not only exhibits a distinctive colorimetric response to 6-mercaptopurine (6-MP), but also displays 6-MP-sensitive photoluminescence quenching. Thus, dual detection channels for 6-MP based on BCPO probe have been developed, and the mechanism has been speculated. Enrichment-electron of the 6-MP can be adsorbed at the boron vacancy orbits of the BCPO by the chemical action. The formation of 6-MP/BCPO complexes trigger the efficient photoluminescence quenching and light-absorbing enhancing of the BCPO, owing to the synergistic effect of the acceptor-excited photo-induced electron/energy transfer, inner filter effect and p/π-π conjugated stacking. Furthermore, the presence of ClO− anion efficaciously sparks the release of the 6-MP molecule from the 6-MP/BCPO complexes, thereby a rapid photo-switch of the BCPO for the 6-MP has been developed. Thus, this study can not only guide the further rational design of the BCPO probe, but also inspire the in-depth application of the BCPO and other nanomaterial-based probes.

Engineering of Broadband Nanoporous Semiconductor Photonic Crystals for Visible-Light-Driven Photocatalysis.

A new class of semiconductor photonic crystals composed of titanium dioxide (TiO2)-functionalized nanoporous anodic alumina (NAA) broadband-distributed Bragg reflectors (BDBRs) for visible-light-driven photocatalysis is presented. NAA-BDBRs produced by double exponential pulse anodization (DEPA) show well-resolved, spectrally tunable, broad photonic stop bands (PSBs), the width of which can be precisely tuned from 70 ± 6 to 153 ± 9 nm (in air) by progressive modification of the anodization period in the input DEPA profile. Photocatalytic efficiency of TiO2-NAA-BDBRs with tunable PSB width upon visible-NIR illumination is studied using three model photodegradation reactions of organics with absorbance bands across the visible spectral regions. Analysis of these reactions allows us to elucidate the interplay of spectral distance between red edge of TiO2-NAA-BDBRs' PSB, electronic bandgap, and absorbance band of model organics in harnessing visible photons for photocatalysis. Photodegradation reaction efficiency is optimal when the PSB's red edge is spectrally close to the electronic bandgap of the functional semiconductor coating. Photocatalytic performance decreases dramatically when the red edge of the PSB is shifted toward visible wavelengths. However, a photocatalytic recovery is observed when the PSB's red edge is judiciously positioned within the proximity of the absorption band of model organics, indicating that TiO2-NAA-BDBRs can harness visible electromagnetic waves to speed up photocatalytic reactions by drastically slowing the group velocity of incident photons at specific spectral regions. Our advances provide new opportunities to better understand and engineer light-matter interactions for photocatalysis, using TiO2-NAA-BDBRs as model nanoporous semiconductor platforms. These high-performing photocatalysts could find broad applicability in visible-NIR light harvesting for environmental remediation, green energy generation, and chemical synthesis.

Laser Writable Multifunctional van der Waals Heterostructures.

Achieving multifunctional van der Waals nanoelectronic devices on one structure is essential for the integration of 2D materials; however, it involves complex architectural designs and manufacturing processes. Herein, a facile, fast, and versatile laser direct write micro/nanoprocessing to fabricate diode, NPN (PNP) bipolar junction transistor (BJT) simultaneously based on a pre-fabricated black phosphorus/molybdenum disulfide heterostructure is demonstrated. The PN junctions exhibit good diode rectification behavior. Due to different carrier concentrations of BP and MoS2 , the NPN BJT, with a narrower base width, renders better performance than the PNP BJT. Furthermore, the current gain can be modulated efficiently through laser writing tunable base width WB , which is consistent with the theoretical results. The maximum gain for NPN and PNP is found to be ≈41 (@WB ≈600nm) and ≈12 (@WB ≈600nm), respectively. In addition, this laser write processing technique also can be utilized to realize multifunctional WSe2 /MoS2 heterostructure device. The current work demonstrates a novel, cost-effective, and universal method to fabricate multifunctional nanoelectronic devices. The proposed approach exhibits promise for large-scale integrated circuits based on 2D heterostructures.

Photosensitive hybrid polysilsesquioxanes for etching-free processing of flexible copper clad laminate

A photosensitive ladder-structured polysilsesquioxane was synthesized for the development of flexible copper clad laminates through electroless plating of Cu. The developed ladder-structured polysilsesquioxane with controlled structure enabled easy introduction of protected thiol and allyl functional group, which under acidic conditions, the thiol group becomes deprotected. This deprotected thiol group enables UV-initiated thiol-ene curing of the exposed regions, while the unexposed regions containing free thiol groups act as seed initiators for Cu electroless plating, and the corresponding negative pattern fabrication process also possible. Through this facile method, we were able to develop flexible copper clad laminates of tunable Cu interconnect width size of high electrical conductivity according to photomask pattern and the insulating dielectric surrounding layer exhibiting low dielectric constant and low loss behavior without any corrosive Cu etching steps.

Dual-Band Folded-End Dipole Antenna for Plastic CubeSats

In this article, a dual-band folded-end dipole antenna is proposed for plastic CubeSat platforms. The proposed antenna has a compact structure which is integrated in a miniaturized satellite, i.e., CubeSat, without any deployment mechanism. This is achieved by folding the dipole antenna around the CubeSat circumference. In addition, by folding the dipole, the antenna provides a dual-band performance centered at 2.5 and 4.7 GHz, respectively. The folded-end dipole forms a square loop with a gap of tunable width which can be adjusted to tune its impedance. Finally, the measured gain of the proposed design is 7 and 4.3 dBi with a −10 dB bandwidth of 500 and 250 MHz at S- and C-band, respectively.

Propagation of optically tunable coherent radiation in a gas of polar molecules

Coherent, optically dressed media composed of two-level molecular systems without inversion symmetry are considered as all-optically tunable sources of coherent radiation in the microwave domain. A theoretical model and a numerical toolbox are developed to confirm the main finding: the generation of low-frequency radiation, and the buildup and propagation dynamics of such low-frequency signals in a medium of polar molecules in a gas phase. The physical mechanism of the signal generation relies on the permanent dipole moment characterizing systems without inversion symmetry. The molecules are polarized with a DC electric field yielding a permanent electric dipole moment in the laboratory frame; the direction and magnitude of the moment depend on the molecular state. As the system is resonantly driven, the dipole moment oscillates at the Rabi frequency and, hence, generates microwave radiation. We demonstrate the tuning capability of the output signal frequency with the drive amplitude and detuning. We find that even though decoherence mechanisms such as spontaneous emission may damp the output field, a scenario based on pulsed illumination yields a coherent, pulsed output of tunable temporal width. Finally, we discuss experimental scenarios exploiting rotational levels of gaseous ensembles of heteronuclear diatomic molecules.

Generation of high-order harmonics with tunable photon energy and spectral width using double pulses

This work theoretically investigates high-order harmonic generation in rare gas atoms driven by two temporally delayed ultrashort laser pulses. Apart from their temporal delay, the two pulses are identical. Using a single-atom model of the laser-matter interaction it is shown that the photon energy of the generated harmonics is controllable within the range of one eV -- a bandwidth comparable to the photon energy of the fundamental field -- by varying the time delay between the generating laser pulses. It is also demonstrated that high-order harmonics generated by double pulses have advantageous characteristics, which mimick certain properties of an extreme ultraviolet (XUV) monochromator. With the proposed method, a simpler setup at a much lower cost and comparatively higher spectral yield can be implemented in contrast to other approaches.

Injectable and Crosslinkable PLGA-Based Microribbons as 3D Macroporous Stem Cell Niche.

Poly(lactide-co-glycolide) (PLGA) has been widely used as a tissue engineering scaffold. However, conventional PLGA scaffolds are not injectable, and do not support direct cell encapsulation, leading to poor cell distribution in 3D. Here, a method for fabricating injectable and intercrosslinkable PLGA microribbon-based macroporous scaffolds as 3D stem cell niche is reported. PLGA is first fabricated into microribbon-shape building blocks with tunable width using microcontact printing, then coated with fibrinogen to enhance solubility and injectability using aqueous solution. Upon mixing with thrombin, firbornogen-coated PLGA microribbons can intercrosslink into 3D scaffolds. When subject to cyclic compression, PLGA microribbon scaffolds exhibit great shock-absorbing capacity and return to their original shape, while conventional PLGA scaffolds exhibit permanent deformation after one cycle. Using human mesenchymal stem cells (hMSCs) as a model cell type, it is demonstrated that PLGA μRB scaffolds support homogeneous cell encapsulation, and robust cell spreading and proliferation in 3D. After 28 days of culture in osteogenic medium, hMSC-seeded PLGA μRB scaffolds exhibit an increase in compressive modulus and robust bone formation as shown by staining of alkaline phosphatase, mineralization, and collagen. Together, the results validate PLGA μRBs as a promising injectable, macroporous, non-hydrogel-based scaffold for cell delivery and tissue regeneration applications.

Retraction of "Preparing Semiconducting Nanoribbons with Tunable Length and Width via Crystallization-Driven Self-Assembly of a Simple Conjugated Homopolymer".

RETURN TO ISSUEPREVRetractionNEXTORIGINAL ARTICLEThis notice is a retraction.Retraction of “Preparing Semiconducting Nanoribbons with Tunable Length and Width via Crystallization-Driven Self-Assembly of a Simple Conjugated Homopolymer”Inho ChoiInho ChoiMore by Inho Choi, Sanghee YangSanghee YangMore by Sanghee Yanghttp://orcid.org/0000-0001-7944-6635, and Tae-Lim Choi*Tae-Lim ChoiMore by Tae-Lim Choihttp://orcid.org/0000-0001-9521-6450Cite this: J. Am. Chem. Soc. 2020, 142, 1, 650Publication Date (Web):December 18, 2019Publication History Published online19 December 2019Published inissue 8 January 2020https://doi.org/10.1021/jacs.9b10101Copyright © 2019 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views4628Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (210 KB) Get e-Alerts Get e-Alerts

Microchannel Stiffness and Confinement Jointly Induce the Mesenchymal-Amoeboid Transition of Cancer Cell Migration.

The physical confinement of cell microenvironment could enhance the invasive capability and drug resistance of cancer cells. However, due to the lack of in vitro experimental platform to mimic both stiffness and confinement of the tumor microenvironment, the underlying mechanism remains elusive. Here, we developed a hydrogel-based microchannel platform with independently tunable channel stiffness and width in a physiological range. We found that the migration speed of the cancer cell is influenced by the synergistic effect of channel stiffness and width. In addition, the mesenchymal-amoeboid transition has a strong correlation with the channel stiffness. Besides, with a developed computational model, the role of nuclear stiffness on cancer migration speed and thus the mesenchymal-amoeboid transition in microchannels was also revealed. This platform is capable of mimicking the native physical microenvironment during metastasis, providing a powerful tool for high-throughput screening applications and investigating the interaction between cancer migration and biophysical microenvironment.