Three-dimensional patterning of MoS2 with ultrafast laser.

Transition metal chalcogenides, a special two-dimensional (2D) material emerged in recent years, possess unique optoelectronic properties and have been used to fabricate various optoelectronic devices. While it is essential to manufacture multifunctional devices with complex nanostructures for practical applications, 2D material devices present a tendency toward miniaturization. However, the controllable fabrication of complex nanostructures on 2D materials remains a challenge. Herein, we propose a method to create designed three-dimensional (3D) patterns on the MoS2 surface by modulating the interaction between an ultrafast laser and MoS2. Three different nanostructures, including flat, bulge, and craters, can be fabricated through laser-induced surface morphology transformation, which is related to thermal diffusion, oxidation, and ablation processes. The MoS2 field effect transistor is fabricated by ultrafast laser excitation which exhibits enhanced electrical properties. This study provides a promising strategy for 3D pattern fabrication, which is helpful for the development of multifunctional microdevices.

Ultrafast Laser Plasmonic Fabrication of Nanocrystals by Molecule Modulation for Photoresponse Multifunctional Structures.

Nanotechnology has attracted wide research attention in constructing functional devices, including integrated circuits, transparent electrodes, and flexible actuators. Bottom-up fabrication is an important approach for functional structure manufacture, however, the controllable fabrication of complex architectures for practical applications has long been a challenge. Here, a novel strategy of laser plasmonic fabrication based on glue molecule modulation is proposed that can assemble metal nanocrystals into interconnected pattern networks. The plasmonic response of nanocrystals is adjustable with molecule modulation, which is a benefit for the effective formation of laser-induced localized oscillating electrons. The further decomposition of molecules and the movement of nanocrystal surface atoms can achieve the coalescence of assembled nanocrystals. It demonstrates that complex architectures can be controllably constructed by molecule level modulation. Through molecule-assisted laser plasmonic fabrication, the functional nanocrystals with enhanced photothermal capacity can be used for information encryption and soft machinery. This work expands the knowledge of bottom-up fabrication and provides a method for designing functional nanocrystals for a wide range of applications.

A Machine Learning-Combined Flexible Sensor for Tactile Detection and Voice Recognition.

Intelligent sensors have attracted substantial attention for various applications, including wearable electronics, artificial intelligence, healthcare monitoring, and human-machine interactions. However, there still remains a critical challenge in developing a multifunctional sensing system for complex signal detection and analysis in practical applications. Here, we develop a machine learning-combined flexible sensor for real-time tactile sensing and voice recognition through laser-induced graphitization. The intelligent sensor with a triboelectric layer can convert local pressure to an electrical signal through a contact electrification effect without external bias, which has a characteristic response behavior when exposed to various mechanical stimuli. With the special patterning design, a smart human-machine interaction controlling system composed of a digital arrayed touch panel is constructed to control electronic devices. Based on machine learning, the real-time monitoring and recognition of the changes of voice are achieved with high accuracy. The machine learning-empowered flexible sensor provides a promising platform for the development of flexible tactile sensing, real-time health detection, human-machine interaction, and intelligent wearable devices.

Laser Induced Coffee-Ring Structure through Solid-Liquid Transition for Color Printing.

Metallic micro/nano structures with special physicochemical properties have undergone rapid development owing to their broad applications in micromachines and microdevices. Ultrafast laser processing is generally accepted as an effective technology for functional structures manufacture, however, the controllable fabrication of specific metallic micro/nano structures remains a challenge. Here, this work proposes a novel strategy of laser induced transient solid-liquid transition to fabricate unique structures. Through modulating the transient state of metal from solid to liquid phase using the initial pulse excitation, the subsequent ultrafast pulse-induced recoil pressure can suppress the plasma emission and removal of liquid phase metals, resulting in the controllable fabrication of coffee-ring structures. The solid-liquid transition dynamics, which related with the transient reflectivity and plasma intensity, are revealed by established two temperature model coupled with molecular dynamics model. The coffee-ring structure exhibits tunable structure color owing to various optical response, which can be used for color printing with large scale and high resolution. This work provides a promising strategy for fabricating functional micro/nano structures, which can greatly broaden the potential applications.

Strong metal-support interactions induced by an ultrafast laser.

Supported metal catalysts play a crucial role in the modern industry. Constructing strong metal-support interactions (SMSI) is an effective means of regulating the interfacial properties of noble metal-based supported catalysts. Here, we propose a new strategy of ultrafast laser-induced SMSI that can be constructed on a CeO2-supported Pt system by confining electric field in localized interface. The nanoconfined field essentially boosts the formation of surface defects and metastable CeOx migration. The SMSI is evidenced by covering Pt nanoparticles with the CeOx thin overlayer and suppression of CO adsorption. The overlayer is permeable to the reactant molecules. Owing to the SMSI, the resulting Pt/CeO2 catalyst exhibits enhanced activity and stability for CO oxidation. This strategy of constructing SMSI can be extended not only to other noble metal systems (such as Au/TiO2, Pd/TiO2, and Pt/TiO2) but also on non-reducible oxide supports (such as Pt/Al2O3, Au/MgO, and Pt/SiO2), providing a universal way to engineer and develop high-performance supported noble metal catalysts.

Stretchable Conductive Fabric Enabled By Surface Functionalization of Commercial Knitted Cloth.

Textile-based stretchable electronic devices are one of the best candidates for future wearable applications, as they can simultaneously provide high compliance and wearing comfort to the human body. Stretchable conductive textile is the fundamental building block for constructing high-performance textile-based stretchable electronic devices. Here, we report a simple strategy for the fabrication of stretchable conductive fabric using commercial knitted cloth as a substrate. Briefly, we coated the fibers of the fabric with a thin layer of poly(styrene-block-butadiene-block-styrene) (SBS) by dip-coating. Then, silver nanoparticles (AgNPs) were loaded on the fabric by sequential absorption and in situ reduction. After loading AgNPs, the conductivity of the fabric could be as high as ∼800 S/m, while its maximal strain at break was higher than 540%. Meanwhile, such fabric also possesses excellent permeability, robust endurance to repeated stretching, long-time washing, and mechanical rubbing or tearing. We further approve that the fabric is less cytotoxic to mammalian skin and antibacterial to microbial, making it safe for on-skin applications. With these multifarious advantages, the fabric developed here is promising for on-skin wearable applications. As a proof-of-concept, we demonstrate its use as an electrode for collecting electrocardiograph signals and electrothermal therapy.

Atomic-level ablation of Au@Ag NRs using ultrafast laser excitation.

Metallic nanorods (NRs) are an important class of materials with widespread applications because of their appealing tunable plasmon resonances, high photothermal conversion efficiency, and chemical stability. It is essential to control the shape and atomic structures of metallic NRs for practical applications. Laser processing of metallic NRs relying on light-matter interactions provides many opportunities. However, the atomic-level fabrication of NRs remains a challenge, and the understanding of laser-induced ablation is still limited. Here, we proposed the atomic-level ablation of Au@Ag NRs using ultrafast laser excitation, which suggests that the near-field effect plays a key role in comparison with thermal evaporation. Through ultrafast laser pulse excitation, abundant atomic steps are fabricated in Au@Ag NRs, which can enhance the surface activity. We suggest that this study highlights the role of the laser near-field effect and also provides a facile strategy to tailor the external shape of metallic NRs at the atomic level, opening a pathway to design metallic NRs for energy and environmental applications.

Ultrafast Laser-Induced Atomic Structure Transformation of Au Nanoparticles with Improved Surface Activity.

Metallic nanoparticles (NPs) play a significant role in nanocatalytic systems, which are important for clean energy conversion, storage, and utilization. Laser fabrication of metallic NPs relying on light-matter interactions provides many opportunities. It is essential to study the atomic structure transformation of nonactive monocrystalline metallic NPs for practical applications. The high-density stacking faults were fabricated in monocrystalline Au NPs through tuning the ultrafast laser-induced relaxation dynamics, and the thermal and dynamic stress effects on the atomic structure transformation were revealed. The atomic structure transformation mainly arises from the thermal effect, and the dynamic stress distribution induced by local energy deposition gives rise to the generation of stacking faults. Au NPs with abundant stacking faults show enhanced surface activity owing to their low coordination number. We suggest that this work expands the knowledge of laser-metallic nanomaterial interactions and provides a method for designing metallic NPs for a wide range of applications.

Skin stretch suturing with Nice knots in the treatment of small- or medium-sized wounds.

BACKGROUND: To investigate the clinical efficacy and outcomes of skin stretch suturing with self-locking sliding Nice knots in the treatment of small- or medium-sized wounds. METHODS: From June 2015 to May 2018, 26 patients with small- or medium-sized wounds were included in the present study. Skin stretch suturing with self-locking slide Nice knots was performed to gradually close the soft-tissue defects in these patients. The time of wound closure and healing was recorded. The color and blood supply of the skin, cutaneous sensation, the stretch of skin, and the hair growth situation of the skin wound were observed and recorded. RESULTS: There were 17 males and 9 females with an average age of 30.65 years (range, 15-48 years). The areas of the soft-tissue defects were between 3.2 × 7.1 cm and 8.0 × 15.2 cm. All patients underwent stretch suturing with self-locking slide Nice knots to close the soft-tissue defects. All wounds were successfully closed and healed. The mean time of wound closure was 10.69 days (range, 5-20 days), and the mean time of wound healing was 16.85 days (range, 10-24 days). The cutaneous sensation of skin wound recovered normally, and the color of the skin wounds was the same as that of normal skin at the last follow-up. The hair growth situation of the skin wounds also returned to normal. CONCLUSIONS: This study revealed that Nice knots yielded an accepted clinical result as a new method to close small- or medium-sized wounds that was simple and less minimally invasive, resulted in progressive tension, did not return to previous results, and partially replace flaps or free skin grafts.

Light Tailoring of Internal Atomic Structure of Gold Nanorods.

Laser processing of gold nanorods (Au NRs) relying on light-matter interaction provides great opportunities in various potential applications. Unveiling the light-induced structure change is a crucial goal in order to control the shape and related properties for practical application. However, the internal atomic structure control of metallic NRs has long been a challenge. Here, the concept of internal atomic structure tailored with light is demonstrated and Au NRs with various internal atomic structures including point defects, twin structures, and polycrystalline nanospheres are fabricated. Experimental characterization and theoretical simulation show that light-induced localized energy deposition and dynamic stresses distribution give rise to atomic structure change. Au NRs with internal defects show enhanced potential to improve activity. The concept of light tailoring of internal atomic structure represents a promising strategy for the rational design of metallic NRs to boost wide applications.

Reshaping enhancement of gold nanorods by femtosecond double-pulse laser.

Gold nanorod (Au NR) is an attractive material due to its superior physical and chemical properties. Various applications in diagnostics and biomedicine have been demonstrated. The single-pulse laser is commonly used to reshape nanoparticles in a solvent; however, the laser-material reaction mechanisms underlying nanoparticle reshaping remain unclear. Here, we report the reshaping of Au NRs by ultrafast pump-probe-like double-pulse laser irradiation to understand the reaction dynamics. We demonstrate the enhancement of double-pulse-induced reshaping, which provides an opportunity to design new Au NR structures. It shows that the reshaping enhancement is dependent on the delay time (${\tau _s}$τs) between a pair of separated pulses. The absorption peak wavelength of Au NRs exposed to the shaped double pulse was lower than that of using a single pulse of the same total fluence when ${\tau _s}$τs was less than the electron-phonon relaxation time. This phenomenon was mainly attributed to changes in electronic heat transport and electron-phonon coupling, which affected the pulse delay-dependent nanorod (NR) temperature.

Topological charge measurement of concentric OAM states using the phase-shift method.

We proposed a method to measure orbital angular momentum (OAM) states by using a multi-zone pure phase grating with the phase-shift technique. In free-space optical communication systems, the topological charges (TCs) of concentric OAM beams are usually detected for decoding, since the diameter of the OAM beam relates to the transmission distance. Two typical concentric OAM beams, concentric Laguerre-Gaussian beams and perfect vortex beams, were generated as incident beams, and the diffraction patterns can be separated by implementing a pure phase grating in the Fourier plane of a 4-f system. By counting the corresponding diffraction fringes, we can identify the TCs of the two OAM states. The simulation results show that the diffraction angles of the concentric OAM beams can be controlled and two concentric OAM states can be measured simultaneously.

Performance of Positron Emission Tomography and Positron Emission Tomography/Computed Tomography Using Fluorine-18-Fluorodeoxyglucose for the Diagnosis, Staging, and Recurrence Assessment of Bone Sarcoma: A Systematic Review and Meta-Analysis.

To investigate the performance of fluorine-18-fluorodeoxyglucose (F-FDG) positron emission tomography (PET) and PET/computed tomography (CT) in the diagnosis, staging, restaging, and recurrence surveillance of bone sarcoma by systematically reviewing and meta-analyzing the published literature.To retrieve eligible studies, we searched the MEDLINE, Embase, and the Cochrane Central library databases using combinations of following Keywords: "positron emission tomography" or "PET," and "bone tumor" or "bone sarcoma" or "sarcoma." Bibliographies from relevant articles were also screened manually. Data were extracted and the pooled sensitivity, specificity, and diagnostic odds ratio (DOR), on an examination-based or lesion-based level, were calculated to appraise the diagnostic accuracy of F-FDG PET and PET/CT. All statistical analyses were performed using Meta-Disc 1.4.Forty-two trials were eligible. The pooled sensitivity and specificity of PET/CT to differentiate primary bone sarcomas from benign lesions were 96% (95% confidence interval [CI], 93-98) and 79% (95% CI, 63-90), respectively. For detecting recurrence, the pooled results on an examination-based level were sensitivity 92% (95% CI, 85-97), specificity 93% (95% CI, 88-96), positive likelihood ratio (PLR) 10.26 (95% CI, 5.99-17.60), and negative likelihood ratio (NLR) 0.11 (95% CI, 0.05-0.22). For detecting distant metastasis, the pooled results on a lesion-based level were sensitivity 90% (95% CI, 86-93), specificity 85% (95% CI, 81-87), PLR 5.16 (95% CI, 2.37-11.25), and NLR 0.15 (95% CI, 0.11-0.20). The accuracies of PET/CT for detecting local recurrence, lung metastasis, and bone metastasis were satisfactory. Pooled outcome estimates of F-FDG PET were less complete compared with those of PET/CT.F-FDG PET and PET/CT showed a high sensitivity for diagnosing primary bone sarcoma. Moreover, PET/CT demonstrated excellent accuracy for the staging, restaging, and recurrence surveillance of bone sarcoma. However, to avoid misdiagnosis, pathological examination or long-term follow-up should be carried out for F-FDG-avid lesions in patients with suspected bone sarcoma.

Overexpression of hypoxia-inducible factor-1α and vascular endothelial growth factor in sacral giant cell tumors and the correlation with tumor microvessel density.

Although classified as benign, giant cell tumors of the bone (GCTB) may be aggressive, recur and even metastasize to the lungs. In addition, the pathogenesis and histogenesis remain unclear; thus, the driving factors behind the strong tumor growth capacity of GCTB require investigation. In the present study, the expression levels of hypoxia-inducible factor (HIF)-1α and vascular endothelial growth factor (VEGF), which are promoted by hypoxic conditions, were determined in 22 sacral GCTB samples using immunohistochemistry and western blot analysis. Furthermore, CD34 expression was analyzed using these methods. The correlation between HIF-1α or VEGF expression and the tumor microvessel density (MVD) was then determined. The results demonstrated that HIF-1α, VEGF and CD34 were overexpressed in the 22 sacral GCTB specimens, and overexpression of HIF-1α and VEGF correlated with the tumor MVD. Thus, the present study has provided novel indicators for the tumor growth capacity of GCTBs.

Diesel oil pool fire characteristic under natural ventilation conditions in tunnels with roof openings.

In order to research the fire characteristic under natural ventilation conditions in tunnels with roof openings, full-scale experiment of tunnel fire is designed and conducted. All the experimental data presented in this paper can be further applied for validation of numerical simulation models and reduced-scale experimental results. The physical model of tunnel with roof openings and the mathematical model of tunnel fire are presented in this paper. The tunnel fire under the same conditions as experiment is simulated using CFD software. From the results, it can be seen that most smoke is discharged directly off the tunnel through roof openings, so roof openings are favorable for exhausting smoke. But along with the decrease of smoke temperatures, some smoke may backflow and mix with the smoke-free layer below, which leads to fall in visibility and is unfavorable for personnel evacuation. So it is necessary to research more efficient ways for improving the smoke removal efficiency, such as early fire detection systems, adequate warning signs and setting tunnel cap.