Theoretical Study on the Structures and Electronic Properties of Tungsten Fluorides at High Pressures.

Transition metal fluorides are a series of strong oxidizing agents. Tungsten (W) fluorides, particularly WF6, have shown broad applications such as luminescence and fluorinating agent. However, other stoichiometries of W fluorides have rarely been studied. It is well-known that pressure can induce structural phase transition, stabilize new compounds, and produce novel properties. In this work, the high-pressure phases of W-F were searched systematically at the pressure range of 0-200 GPa through first-principles swarm-intelligence structural search calculations. A new stoichiometry of WF4 has been predicted to be stable under high pressures. On the other hand, two new high-pressure phases of WF6 with the symmetries of P 2 1 ${{P2}_{1}}$ /m and P ${P}$ -1 were found with decahedral structural units. The electronic properties of the W-F compounds were then investigated. The predicted stable WF6 high-pressure phases maintain semiconducting features, since the W atom provides all its valence electrons to fluorine. We evaluated the oxidizing ability of WF6 by calculating its electron affinity potential. The high pressure P 2 1 ${{P2}_{1}}$ /m WF6 molecular phase shows higher oxidation capacity than the ambient phase. The built pressure-composition phase diagram and the theoretical results of W-F system provide some useful information for experimental synthesis.

Diagnosis of SPECT/CT bone imaging combined with two serum examinations in patients with bone metastases from pulmonary cancer

Purpose To study the clinical diagnostic value of SPECT/CT bone imaging combined with two serum examinations in patients with bone metastases from pulmonary cancer. Methods The clinical data of 120 patients consistent with pulmonary cancer admitted to the First Affiliated Hospital of Hebei North University from March 2019 to December 2019 were selected for retrospective analysis, and they were divided into the bone metastasis group (n = 58) and non-bone metastasis group (n = 62) according to comprehensive evaluation result of X-ray, CT, MRI and clinical follow-up. The CT values of patients were obtained by SPECT/CT bone imaging to compare serum levels of ALP (alkaline phosphatase belongs to phosphoric monoester hydrolases, as a specific phosphatase, mainly in body tissues and body fluid) and BAP (bone alkaline phosphatase is formed by different modification and processing of alkaline phosphatase, and is mainly released by osteoblasts) and CT values of patients in both groups, using receiver operating characteristic (ROC) curve to evaluate the diagnostic efficacy of single detection and combined detection. Results SPECT/CT bone imaging in patients with bone metastasis from pulmonary cancer showed abnormal radioactive accumulation in spine, pelvis and bilateral ribs. Serum ALP, BAP and CT values in bone metastasis group were overtly higher than the non-bone metastasis group (P < 0.001). Logistic regression analysis showed that serum ALP, BAP and CT value were independent risk factors for bone metastasis from pulmonary cancer. The AUC value and Youden index of combined diagnosis were higher than those of single diagnosis. Conclusion SPECT/CT bone imaging combined with serum detection of ALP and BAP in patients with pulmonary cancer is helpful for early diagnosis of bone metastasis, which provides more basis for the formulation and selection of clinical treatment options (AU)

Diagnosis of SPECT/CT bone imaging combined with two serum examinations in patients with bone metastases from pulmonary cancer.

PURPOSE: To study the clinical diagnostic value of SPECT/CT bone imaging combined with two serum examinations in patients with bone metastases from pulmonary cancer. METHODS: The clinical data of 120 patients consistent with pulmonary cancer admitted to the First Affiliated Hospital of Hebei North University from March 2019 to December 2019 were selected for retrospective analysis, and they were divided into the bone metastasis group (n = 58) and non-bone metastasis group (n = 62) according to comprehensive evaluation result of X-ray, CT, MRI and clinical follow-up. The CT values of patients were obtained by SPECT/CT bone imaging to compare serum levels of ALP (alkaline phosphatase belongs to phosphoric monoester hydrolases, as a specific phosphatase, mainly in body tissues and body fluid) and BAP (bone alkaline phosphatase is formed by different modification and processing of alkaline phosphatase, and is mainly released by osteoblasts) and CT values of patients in both groups, using receiver operating characteristic (ROC) curve to evaluate the diagnostic efficacy of single detection and combined detection. RESULTS: SPECT/CT bone imaging in patients with bone metastasis from pulmonary cancer showed abnormal radioactive accumulation in spine, pelvis and bilateral ribs. Serum ALP, BAP and CT values in bone metastasis group were overtly higher than the non-bone metastasis group (P < 0.001). Logistic regression analysis showed that serum ALP, BAP and CT value were independent risk factors for bone metastasis from pulmonary cancer. The AUC value and Youden index of combined diagnosis were higher than those of single diagnosis. CONCLUSION: SPECT/CT bone imaging combined with serum detection of ALP and BAP in patients with pulmonary cancer is helpful for early diagnosis of bone metastasis, which provides more basis for the formulation and selection of clinical treatment options.

The pan-genome and local adaptation of Arabidopsis thaliana.

Arabidopsis thaliana serves as a model species for investigating various aspects of plant biology. However, the contribution of genomic structural variations (SVs) and their associate genes to the local adaptation of this widely distribute species remains unclear. Here, we de novo assemble chromosome-level genomes of 32 A. thaliana ecotypes and determine that variable genes expand the gene pool in different ecotypes and thus assist local adaptation. We develop a graph-based pan-genome and identify 61,332 SVs that overlap with 18,883 genes, some of which are highly involved in ecological adaptation of this species. For instance, we observe a specific 332 bp insertion in the promoter region of the HPCA1 gene in the Tibet-0 ecotype that enhances gene expression, thereby promotes adaptation to alpine environments. These findings augment our understanding of the molecular mechanisms underlying the local adaptation of A. thaliana across diverse habitats.

Comparison of value of 640-slice CT kidney scan and kidney ultrasound in the diagnosis of chronic kidney disease.

To explore the value of 640-slice CT kidney scan and kidney ultrasound (KUS) in the diagnosis of chronic kidney disease (CKD). The data of 120 CKD patients at our institution between June 2019 and September 2020 were analyzed, and they were randomly divided into ultrasound (US) group (n = 40, KUS), CT group (n = 40) first receiving a plane CT scan to determine the scope of dynamic volume scan, which was performed for scans in cortical, parenchymal, and delayed phases with bolus injection of contrast medium, and combined group (n = 40, KUS and 640-slice CT kidney scan), with the images obtained read and analyzed. The subjective scores and effective radiation doses of 640-layer CT kidney scan were counted to calculate the detection rates. The subjective scores of 640-slice CT kidney scan in plane scan, cortical phase, parenchymal phase, and delayed phase were (1.23 ± 0.42), (1.80 ± 0.40), (2.08 ± 0.26), (2.18 ± 0.38) in the CT group and (1.18 ± 0.38), (1.85 ± 0.36), (2.08 ± 0.26), (2.20 ± 0.40) in the combined group. The effective radiation doses in the CT and combined groups were (1.92 ± 0.32) mSv and (1.95 ± 0.35) mSv. The reading results showed that 26 cases (65.0%), 30 cases (75.0%), and 38 cases (95.0%) were detected in the US, CT and combined groups, respectively, with remarkably higher detection rate in the combined group than the US and CT groups (P < 0.05). 640-slice CT kidney scan and KUS can be adopted for the diagnosis of CKD; with low radiation dose, good image quality, and higher detection rate in the former, their combination can improve the clinical detection rate of CKD and is worth promoting.

Sunlight-powered self-excited oscillators for sustainable autonomous soft robotics.

As the field of soft robotics advances, full autonomy becomes highly sought after, especially if robot motion can be powered by environmental energy. This would present a self-sustained approach in terms of both energy supply and motion control. Now, autonomous movement can be realized by leveraging out-of-equilibrium oscillatory motion of stimuli-responsive polymers under a constant light source. It would be more advantageous if environmental energy could be scavenged to power robots. However, generating oscillation becomes challenging under the limited power density of available environmental energy sources. Here, we developed fully autonomous soft robots with self-sustainability based on self-excited oscillation. Aided by modeling, we have successfully reduced the required input power density to around one-Sun level through a liquid crystal elastomer (LCE)-based bilayer structure. The autonomous motion of the low-intensity LCE/elastomer bilayer oscillator "LiLBot" under low energy supply was achieved by high photothermal conversion, low modulus, and high material responsiveness simultaneously. The LiLBot features tunable peak-to-peak amplitudes from 4 to 72 degrees and frequencies from 0.3 to 11 hertz. The oscillation approach offers a strategy for designing autonomous, untethered, and sustainable small-scale soft robots, such as a sailboat, walker, roller, and synchronized flapping wings.

Photoinduced Dual Shape Programmability of Covalent Adaptable Networks with Remarkable Mechanical Properties.

As classic shape memory polymers featuring shape reconfiguration of temporary state, covalent adaptable networks containing reversible bonds can enable permanent-state reconfigurability through topological rearrangement via dynamic bond exchange. Yet, such an attractive dual shape programmability is limited by the actuation mode of direct heat transfer and poor mechanical properties, restricting its control precision and functionality. Herein, we presented a method to create nanocomposites with photomodulated dual shape programmability and remarkable mechanical properties leading the fields of covalent adaptable networks. MXene, whose photothermal efficiency was revealed to be regulated by the etching method and delamination, was introduced into polyurethane networks. Upon adjusting the light intensity, the dual shape programmability of both permanent and temporary states could be accomplished, which exhibited potential in information recognition, photowriting paper, etc. Furthermore, owing to the dynamic transcarbamoylation at elevated temperatures, such a phototriggered dual shape programmability could be maintained after the self-healing and reprocessing.

Comparison of Diagnostic Value for Chronic Kidney Disease between 640-Slice Computed Tomography Kidney Scan and Conventional Computed Tomography Scan.

Objective: To explore the diagnostic value for chronic kidney disease (CKD) between 640-slice computed tomography (CT) kidney scan and conventional CT scan. Methods: A total of 120 CKD patients who received kidney plain scan plus enhanced examination in the CT room of the Medical Imaging Department of our hospital from June 2019 to September 2019 were selected and randomly divided into the experimental group (n = 60) and the control group (n = 60). Patients in the control group received the conventional CT plain scan and enhanced scan, and for patients in the experimental group, CT plain scan was performed first, the range of 640-slice CT dynamic volume scan was determined, and after bolus injection of contrast agent, dynamic volume scan was performed for scanning in the cortical phase, myeloid phase, and secretory phase. The imaging quality and effective scanning dose were compared between the two modalities, and the relationship between CT values obtained from 640-slice CT scan and conventional CT scan and the renal impairment was analyzed. Results: Compared with the control group, the image quality of 640-slice CT scan conducted in the experimental group was significantly better (P < 0.05); the effective radiation doses of the experimental group and the control group were, respectively, (1.89 ± 0.32) mSv and (3.26 ± 0.47) mSv, indicating that the dose was significantly lower in the experimental group than in the control group (t = 18.664, P < 0.001), and the correlation analysis showed that the relationship between the sum of CT values in the cortical phase of both kidneys and kidney injury in the experimental group was r = 0.835, P < 0.001. Conclusion: Both 640-slice CT kidney scan and conventional CT scan can be used in the diagnosis of CKD. 640-slice CT has a lower radiation dose, better image quality, and higher application value.

Comparison of the Application Value for Diagnosis of Chronic Kidney Disease between Color Doppler Flow Quantification Technique and Computed Tomography.

Objective: The aim of this study is to compare the application value for diagnosis of chronic kidney disease (CKD) between the color Doppler flow quantification (CDFQ) technique and computed tomography (CT). Methods: The clinical data of 88 hospitalized patients treated in the Renal Medicine of our hospital and diagnosed with CKD after pathological examination from June 2020 to June 2021 were selected for the retrospective analysis, and 32 individuals with normal physical examination results in the same period were selected as the control group. All study subjects received CDFQ and 640-slice volume CT examination, and by plotting the ROC curves, the clinical value of different diagnostic modalities was analyzed. Results: The 3D renal volumes between the stage 1 group and control group were significantly different (P < 0.05); the 3D renal volumes between the stage 2 group and control group and between the stage 2 group and stage 1 group were significantly different (P < 0.05); in the comparison between the stage 3 group versus control group/stage 2 group, the RI values, 3D renal volumes, and cortical thicknesses were significantly different (P < 0.05); in the comparison between the stage 4 group versus control group/stage 1 group, the RI values, 3D renal volumes, and cortical thicknesses were significantly different, and between the stage 4 group and stage 2 group, the RI values and cortical thicknesses were significantly different (P < 0.05); in the comparison between the stage 5 group versus control group/stage 1 group/stage 2 group/stage 3 group, the RI values, 3D renal volumes, and cortical thicknesses were significantly different, and between the stage 5 group and stage 4 group, the RI values and 3D renal volumes were significantly different (P < 0.05); among various groups, the measurement indicators of 640-slice volume CT scan were significantly different (P < 0.05); and in terms of disease classification, the AUC value, positive predictive value, negative predictive value, sensitivity, and specificity of 640-slice volume CT were higher than those of CDFQ diagnosis. Conclusion: 640-slice volume CT has a higher efficacy in diagnosing CKD and can provide a reliable basis for the selection of treatment schemes for CKD patients.

Tough-Hydrogel Reinforced Low-Tortuosity Conductive Networks for Stretchable and High-Performance Supercapacitors.

All-solid-state supercapacitors are seeing emerging applications in flexible and stretchable electronics. Supercapacitors with high capacitance, high power density, simple form factor, and good mechanical robustness are highly desired, which demands electrode materials with high surface area, high mass loading, good conductivity, larger thickness, low tortuosity, and high toughness. However, it has been challenging to simultaneously realize them in a single material. By compositing a superficial layer of tough hydrogel on conductive and low tortuous foams, a thick capacitor electrode with large capacitance (5.25 F cm-2 ), high power density (41.28 mW cm-2 ), and good mechanical robustness (ε = 140%, Γ = 1000 J m-2 ) is achieved. The tough hydrogel serves as both a load-bearing layer to maintain structural integrity during deformation and a permeable binder to allow interaction between the conductive electrode and electrolyte. It is shown that the tough hydrogel reinforcement is beneficial for both electrical and mechanical stability. With a simple design and facile fabrication, this strategy is generalizable for various conductive materials.

Somatosensory actuator based on stretchable conductive photothermally responsive hydrogel.

Mimicking biological neuromuscular systems' sensory motion requires the unification of sensing and actuation in a singular artificial muscle material, which must not only actuate but also sense their own motions. These functionalities would be of great value for soft robotics that seek to achieve multifunctionality and local sensing capabilities approaching natural organisms. Here, we report a soft somatosensitive actuating material using an electrically conductive and photothermally responsive hydrogel, which combines the functions of piezoresistive strain/pressure sensing and photo/thermal actuation into a single material. Synthesized through an unconventional ice-templated ultraviolet-cryo-polymerization technique, the homogenous tough conductive hydrogel exhibited a densified conducting network and highly porous microstructure, achieving a unique combination of ultrahigh conductivity (36.8 milisiemens per centimeter, 103-fold enhancement) and mechanical robustness, featuring high stretchability (170%), large volume shrinkage (49%), and 30-fold faster response than conventional hydrogels. With the unique compositional homogeneity of the monolithic material, our hydrogels overcame a limitation of conventional physically integrated sensory actuator systems with interface constraints and predefined functions. The two-in-one functional hydrogel demonstrated both exteroception to perceive the environment and proprioception to kinesthetically sense its deformations in real time, while actuating with near-infinite degrees of freedom. We have demonstrated a variety of light-driven locomotion including contraction, bending, shape recognition, object grasping, and transporting with simultaneous self-monitoring. When connected to a control circuit, the muscle-like material achieved closed-loop feedback controlled, reversible step motion. This material design can also be applied to liquid crystal elastomers.

Tunable Sponge-Like Hierarchically Porous Hydrogels with Simultaneously Enhanced Diffusivity and Mechanical Properties.

Crosslinked polymers and gels are important in soft robotics, solar vapor generation, energy storage, drug delivery, catalysis, and biosensing. However, their attractive mass transport and volume-changing abilities are diffusion-limited, requiring miniaturization to avoid slow response. Typical approaches to improving diffusion in hydrogels sacrifice mechanical properties by increasing porosity or limit the total volumetric flux by directionally confining the pores. Despite tremendous efforts, simultaneous enhancement of diffusion and mechanical properties remains a long-standing challenge hindering broader practical applications of hydrogels. In this work, cononsolvency photopolymerization is developed as a universal approach to overcome this swelling-mechanical property trade-off. The as-synthesized poly(N-isopropylacrylamide) hydrogel, as an exemplary system, presents a unique open porous network with continuous microchannels, leading to record-high volumetric (de)swelling speeds, almost an order of magnitude higher than reported previously. This swelling enhancement comes with a simultaneous improvement in Young's modulus and toughness over conventional hydrogels fabricated in pure solvents. The resulting fast mass transport enables in-air operation of the hydrogel via rapid water replenishment and ultrafast actuation. The method is compatible with 3D printing. The generalizability is demonstrated by extending the technique to poly(N-tertbutylacrylamide-co-polyacrylamide) and polyacrylamide hydrogels, non-temperature-responsive polymer systems, validating the present hypothesis that cononsolvency is a generic phenomenon driven by competitive adsorption.

Strong tough hydrogels via the synergy of freeze-casting and salting out.

Natural load-bearing materials such as tendons have a high water content of about 70 per cent but are still strong and tough, even when used for over one million cycles per year, owing to the hierarchical assembly of anisotropic structures across multiple length scales1. Synthetic hydrogels have been created using methods such as electro-spinning2, extrusion3, compositing4,5, freeze-casting6,7, self-assembly8 and mechanical stretching9,10 for improved mechanical performance. However, in contrast to tendons, many hydrogels with the same high water content do not show high strength, toughness or fatigue resistance. Here we present a strategy to produce a multi-length-scale hierarchical hydrogel architecture using a freezing-assisted salting-out treatment. The produced poly(vinyl alcohol) hydrogels are highly anisotropic, comprising micrometre-scale honeycomb-like pore walls, which in turn comprise interconnected nanofibril meshes. These hydrogels have a water content of 70-95 per cent and properties that compare favourably to those of other tough hydrogels and even natural tendons; for example, an ultimate stress of 23.5 ± 2.7 megapascals, strain levels of 2,900 ± 450 per cent, toughness of 210 ± 13 megajoules per cubic metre, fracture energy of 170 ± 8 kilojoules per square metre and a fatigue threshold of 10.5 ± 1.3 kilojoules per square metre. The presented strategy is generalizable to other polymers, and could expand the applicability of structural hydrogels to conditions involving more demanding mechanical loading.

Cephalopod-Inspired Chromotropic Ionic Skin with Rapid Visual Sensing Capabilities to Multiple Stimuli.

Biological skin systems can perceive various external stimuli through ion transduction. Especially, the skin of some advanced organisms such as cephalopods can further promptly change body color by manipulating photonic nanostructures. However, the current skin-inspired soft iontronics lack the rapid full-color switching ability to respond to multiple stimuli including tension, pressure, and temperature. Here, an intelligent chromotropic iontronics with these fascinating functions is developed by constructing a biomimetic ultrastructure with anisotropic electrostatic repulsion. This skin-like chromotropic iontronics can synchronously realize electrical response and optical visualization to mechanical strain and tactile sensation by adjusting the ultrastructure in cooperation with ionic mechanotransduction. Notably, it can perform instantaneous geometric changes to thermal stimuli via an anisotropic electrostatic repulsion interior. Such a capability allows bionic skin to transduce temperature or infrared light into ionic signals and color changes in real time. The design of anisotropic photonic nanostructures expands the intelligent application for soft iontronics at higher levels, providing a concise, multifunctional, interactive sensing platform that dynamically displays stimuli information on its body.

Poly(vinyl alcohol) Hydrogels with Broad-Range Tunable Mechanical Properties via the Hofmeister Effect.

Hydrogels, exhibiting wide applications in soft robotics, tissue engineering, implantable electronics, etc., often require sophisticately tailoring of the hydrogel mechanical properties to meet specific demands. For examples, soft robotics necessitates tough hydrogels; stem cell culturing demands various tissue-matching modulus; and neuron probes desire dynamically tunable modulus. Herein, a strategy to broadly alter the mechanical properties of hydrogels reversibly via tuning the aggregation states of the polymer chains by ions based on the Hofmeister effect is reported. An ultratough poly(vinyl alcohol) (PVA) hydrogel as an exemplary material (toughness 150 ± 20 MJ m-3 ), which surpasses synthetic polymers like poly(dimethylsiloxane), synthetic rubber, and natural spider silk is fabricated. With various ions, the hydrogel's various mechanical properties are continuously and reversibly in situ modulated over a large window: tensile strength from 50 ± 9 kPa to 15 ± 1 MPa, toughness from 0.0167 ± 0.003 to 150 ± 20 MJ m-3 , elongation from 300 ± 100% to 2100 ± 300%, and modulus from 24 ± 2 to 2500 ± 140 kPa. Importantly, the ions serve as gelation triggers and property modulators only, not necessarily required to remain in the gel, maintaining the high biocompatibility of PVA without excess ions. This strategy, enabling high mechanical performance and broad dynamic tunability, presents a universal platform for broad applications from biomedicine to wearable electronics.

[Soil phosphorus forms and phosphorus solubilizing bacteria distribution after restoration from seriously burning in Greater Khingan Mountain areas, China]. / å¤§å ´å®‰å²­é‡åº¦ç«çƒ§è¿¹åœ°æ¢å¤åŽåœŸå£¤ç£·å½¢æ€ä¸Žè§£ç£·ç»†èŒåˆ†å¸ƒç‰¹å¾.

To understand the contents of various phosphorus forms, phosphorus solubilizing bacte-rial community structure and the relationship between them in soils after restoration from the seriously burning, we collected soil samples from artificial restoration (Pinus sylvestris var. mongolica plantation, Larix gmelinii plantation), artificial accelerated natural restoration (secondary forest) and natural restoration (natural secondary forest) stands in Greater Khingan Mountain area. Using methods of Sui et al. modified from Hedley phosphorus fractionation, we measured the contents of different phosphorus forms in rhizosphere soil and bulk soil (0-10, 10-20 cm). Abundances of phosphorus solubilizing bacteria were quantified by high-throughput sequencing method. The results showed that the contents of H2O-Pi, NaHCO3-Pi and NaHCO3-Poin 0-10 cm bulk soil and NaHCO3-Po in rhizosphere soil followed the order of L. gmelinii plantation : P. sylvestris var. mongolica plantation : natural secondary forest : secondary forest. The contents of H2O-Pi, NaHCO3-Pi, NaHCO3-Po in 10-20 cm bulk soil and H2O-Pi, NaHCO3-Pi in rhizosphere soil followed the order of L. gmelinii plantation : P. sylvestris var. mongolica plantation : secondary forest : natural secondary forest. The ratios of contents of H2O-Pi, NaHCO3-Pi and NaHCO3-Po in rhizosphere to those in bulk soil (R/S) were higher than 1 in all forest stands. The moderately labile NaOH-P included NaOH-Pi and NaOH-Po. The content of NaOH-P was in order of L. gmelinii plantation : natural secondary forest : secondary forest : P. sylvestris var. mongolica plantation in 0-10 cm layer of bulk and rhizosphere soil, and ranked as L. gmelinii plantation : P. sylvestris var. mongolica plantation : secondary forest : natural secondary forest in 10-20 cm layer of bulk soil. There was rhizosphere effect of NaOH-P in the soil. The stable HCl-P included HCl-Pi and HCl-Po. The content of HCl-P followed the order of L. gmelinii plantation : natural secondary forest : P. sylvestris var. mongolica plantation : secondary forest in 0-10 cm layer of bulk soil,and ranked as L. gmelinii plantation : P. sylvestris var. mongolica plantation : natural secondary forest : secondary forest in the 10-20 cm layer. The content of residual-P in the soil was not sensitive to restoration methods. Bradyrhizobium, Streptomyces, Burkholderia and Bacillus were the main phosphorus solubilizing bacteria across all forest stands. The abundances of phosphorus solubilizing bacteria in soil of L. gmelinii plantation and P. sylvestris var. mongolica plantation were significantly higher than that of secondary forest and natural secondary forest. Results of redundancy analysis showed that the correlation between phosphorus solubilizing bacteria and various phosphorus forms was different. Our results showed that artificial afforestation was more conducive in improving the availability of phosphorus in soil and the abundance of phosphorus solubilizing bacteria.

Artificial phototropism for omnidirectional tracking and harvesting of light.

Many living organisms track light sources and halt their movement when alignment is achieved. This phenomenon, known as phototropism, occurs, for example, when plants self-orient to face the sun throughout the day. Although many artificial smart materials exhibit non-directional, nastic behaviour in response to an external stimulus, no synthetic material can intrinsically detect and accurately track the direction of the stimulus, that is, exhibit tropistic behaviour. Here we report an artificial phototropic system based on nanostructured stimuli-responsive polymers that can aim and align to the incident light direction in the three-dimensions over a broad temperature range. Such adaptive reconfiguration is realized through a built-in feedback loop rooted in the photothermal and mechanical properties of the material. This system is termed a sunflower-like biomimetic omnidirectional tracker (SunBOT). We show that an array of SunBOTs can, in principle, be used in solar vapour generation devices, as it achieves up to a 400% solar energy-harvesting enhancement over non-tropistic materials at oblique illumination angles. The principle behind our SunBOTs is universal and can be extended to many responsive materials and a broad range of stimuli.

Homogeneous Freestanding Luminescent Perovskite Organogel with Superior Water Stability.

Metal-halide perovskites have become appealing materials for optoelectronic devices. While the fast advancing stretchable/wearable devices require stability, flexibility and scalability, current perovskites suffer from ambient-environmental instability and incompatible mechanical properties. Recently perovskite-polymer composites have shown improved in-air stability with the protection of polymers. However, their stability remains unsatisfactory in water or high-humidity environment. These methods also suffer from limited processability with low yield (2D film or beads) and high fabrication cost (high temperature, air/moisture-free conditions), thereby limiting their device integration and broader applications. Herein, by combining facile photo-polymerization with room-temperature in-situ perovskite reprecipitation at low energy cost, a one-step scalable method is developed to produce freestanding highly-stable luminescent organogels, within which CH3 NH3 PbBr3 nanoparticles are homogeneously distributed. The perovskite-organogels present a record-high stability at different pH and temperatures, maintaining their high quantum yields for > 110 days immersing in water. This paradigm is universally applicable to broad choices of polymers, hence casting these emerging luminescent materials to a wide range of mechanical properties tunable from rigid to elastic. With intrinsically ultra-stretchable photoluminescent organogels, flexible phosphorous layers were demonstrated with > 950% elongation. Rigid perovskite gels, on the other hand, permitted the deployment of 3D-printing technology to fabricate arbitrary 2D/3D luminescent architectures.

Soft phototactic swimmer based on self-sustained hydrogel oscillator.

Oscillations are widely found in living organisms to generate propulsion-based locomotion often driven by constant ambient conditions, such as phototactic movements. Such environment-powered and environment-directed locomotions may advance fully autonomous remotely steered robots. However, most man-made oscillations require nonconstant energy input and cannot perform environment-dictated movement. Here, we report a self-sustained soft oscillator that exhibits perpetual and untethered locomotion as a phototactic soft swimming robot, remotely fueled and steered by constant visible light. This particular out-of-equilibrium actuation arises from a self-shadowing-enabled negative feedback loop inherent in the dynamic light-material interactions, promoted by the fast and substantial volume change of the photoresponsive hydrogel. Our analytical model and governing equation unveil the oscillation mechanism and design principle with key parameters identified to tune the dynamics. On this autonomous oscillator platform, we establish a broadly applicable principle for converting a continuous input into a discontinuous output. The modular design can be customized to accommodate various forms of input energy and to generate diverse oscillatory behaviors. The hydrogel oscillator showcases agile life-like omnidirectional motion in the entire three-dimensional space with near-infinite degrees of freedom. The large force generated by the powerful and long-lasting oscillation can sufficiently overcome water damping and effectively self-propel away from a light source. Such a hydrogel oscillator-based all-soft swimming robot, named OsciBot, demonstrated high-speed and controllable phototactic locomotion. This autonomous robot is battery free, deployable, scalable, and integratable. Artificial phototaxis opens broad opportunities in maneuverable marine automated systems, miniaturized transportation, and solar sails.

Draw-Spinning of Kilometer-Long and Highly Stretchable Polymer Submicrometer Fibers.

A new method is developed to directly spinning perfectly uniaxial fibers in an ultrafast manner. Besides, this method can tune the fibers' diameter through adjusting processing parameters such as the feeding rate of precursors. Uniaxial nylon 66 fibers prepared via this method show superior mechanical properties due to the alignment in each level of the structure.