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Intelligent micromachines that respond to external light stimuli have a broad range of potential applications, such as microbots, biomedicine, and adaptive optics. However, artificial light-driven intelligent micromachines with a low actuation threshold, rapid responsiveness, and designable and precise 3D transformation capability remain unachievable to date. Here, a single-material and one-step 4D printing strategy are proposed to enable the nanomanufacturing of agile and low-threshold light-driven 3D micromachines with programmable shape-morphing characteristics. The as-developed carbon nanotube-doped composite hydrogel simultaneously enhanced the light absorption, thermal conductivity, and mechanical modulus of the crosslinked network, thus significantly increasing the light sensitivity and response speed of micromachines. Moreover, the structural design and assembly of asymmetric microscale mechanical metamaterial unit cells enable the highly efficient additive nanomanufacturing of 3D shape-morphable micromachines with large dynamic modulation and spatiotemporal controllability. Using this strategy, the world's smallest artificial beating heart with programmable light-stimulus responsiveness for the cardiac cycle is successfully printed. This 4D printing method paves the way for the construction of multifunctional intelligent micromachines for bionics, drug delivery, integrated microsystems, and other fields.

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Quasi-1D titanium trisulfide (TiS3) has strong in-plane anisotropy with a direct band gap of about 1 eV, which has attracted wide attention in the fields of microelectronics and optoelectronics. However, the investigation of in situ synthesis, synthetic mechanism, and nonlinear optical properties of TiS3 is rarely reported. In this work, we developed a transfer-free method to grow TiS3 nanoribbons, successfully reducing the synthesis time from a few days to less than 24 h without pretreatment. Raman spectroscopy revealed TiS3 was not directly synthesized by titanium (Ti) and sulfur (S) but by the further sulfurization reaction of intermediate product TiS2. Moreover, the polarized four-wave mixing (FWM) imaging of the as-grown TiS3 samples was conducted by ultrafast nonlinear optical spectroscopy for the first time, identifying the crystal axis orientation of TiS3 accurately and quickly. Our work not only provides a rapid growth method for transfer-free synthesis of TiS3 nanoribbons on SiO2/Si substrates but also investigate the fast and non-destructive ultrafast nonlinear optical characterization of quasi-1D TiS3, which lays a foundation for understanding the synthetic mechanism and physicochemical properties of transition metal trisulfides (TMTCs) and promoting the functional device applications of TMTCs represented by TiS3.

The occurrence and severity of truck crashes generally involve complex interactions among factors correlated to driver characteristics, vehicle attributes, roadway geometry and environment conditions. Thus, the elucidation of the significance of these potential contributory factors is critical when developing safety improvement countermeasures. To this end, data from a total of 1175 crashes involving at least one large truck and collected between 2010 and 2015 from two typical freeways in mountainous areas in Jiangxi and Shaanxi (China), were analyzed using a partial proportional odds model to determine the significant risk factors for injury severity of these crashes. Fourteen total explanatory variables, including the age of the driver, seatbelt status, number of vehicle involved, type of transport, freight conditions, brake system status, disregarding speed limit or not, following distance, horizontal roadway alignment, vertical roadway alignment, seasons, day of week, time of crash, and weather were found to significantly affect the severities of the truck crashes. In addition, old drivers, involvement of multiple vehicles, failure to wear seatbelts, overloading, speeding, brake failure and risky following behavior, curve section, seasons (summer, autumn and winter), nighttime period, and adverse weather conditions were also found to significantly increase the likelihood of injury and fatality crashes. Taken together, these findings may serve as a useful guide for developing legislation and technical countermeasures to ensure truck safety on freeways in mountainous regions, particularly in the context of a developing country.

Two-dimensional (2D) material photodetectors have received considerable attention in optoelectronics as a result of their extraordinary properties, such as passivated surfaces, strong light− matter interactions, and broad spectral responses. However, single 2D material photodetectors still suffer from low responsivity, large dark current, and long response time as a result of their atomic-level thickness, large binding energy, and susceptibility to defects. Here, a transition metal trichalcogenide TiS 3 with excellent photoelectric characteristics, including a direct bandgap (1.1 eV), high mobility, high air stability, and anisotropy, is selected to construct a type-II heterojunction with few-layer MoS 2 , aiming to improve the performance of 2D photodetectors. An ultrahigh photoresponsivity of the TiS 3 /MoS 2 heterojunction of 48 666 A/W at 365 nm, 20 000 A/W at 625 nm, and 251 A/W at 850 nm is achieved under light-emitting diode illumination. The response time and dark current are 2 and 3 orders of magnitude lower than those of the current TiS 3 photodetector with the highest photoresponsivity (2500 A/W), respectively. Furthermore, polarized four-wave mixing spectroscopy and polarized photocurrent measurements verify its polarization-sensitive characteristics. This work confirms the excellent potential of TiS 3 /MoS 2 heterojunctions for air-stable, highperformance, polarization-sensitive, and multiband photodetectors, and the excellent type-II TiS 3 /MoS 2 heterojunction system may accelerate the design and fabrication of other 2D functional devices.

Structural wrinkles in nature have been widely imitated to enhance the surface functionalities of objects, especially three-dimensional (3D) architectured wrinkles, holding promise for emerging applications in mechanical, electrical, and biological processes. However, the fabrication of user-defined 3D nanowrinkled architectures is a long-pending challenge. Here, we propose a bottom-up laser direct assembly strategy to fabricate multidimensional nanowrinkled architectures in a single-material one-step process. Through the introduction of laser-induced thermal transition into a 3D nanoprinting process for leading the point-by-point nanoscale wrinkling and the self-organization of wrinkle structures, we have demonstrated the program-controlled and on-demand fabrication of multidimensional nanowrinkled structures. Moreover, the precise control of wrinkle morphology with an optimal wavelength of 40 nanometers and the regulation of the dynamic transformation of wrinkled cellular microstructures via interfacial stress mismatch engineering have been achieved. This study provides a universal protocol for constructing nearly arbitrary nanowrinkled architectures and facilitates a new paradigm in nanostructure manufacturing.

Despite of tremendous potential of multiphoton lithography (MPL) in laboratorial and industrial applications, simultaneous achievement of high throughput, high accuracy, high design freedom, and a broad range of material structuring capabilities remains a long-pending challenge. To address the issue, we propose an acousto-optic scanning with spatial-switching multispots (AOSS) method. Inertia-free acousto-optic scanning and nonlinear swept techniques have been developed for achieving ultrahigh-speed and aberration-free scanning. Moreover, a spatial optical switch concept has been implemented to significantly boost the lithography throughput while maintaining high resolution and high design freedom. An eight-foci AOSS system has demonstrated a record-high 3D printing rate of 7.6×10^7 voxel/s, which is nearly one order of magnitude higher than earlier scanning MPL, exhibiting its promise for future scalable 3D nanomanufacturing.