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The dynamic control of terahertz (THz) wave transmission on flexible functional materials is a fundamental building block for wearable electronics and sensors in the THz range. However, achieving high-efficiency THz modulation and low insertion loss is a great challenge while maintaining the excellent flexibility and stretchability of the materials. Herein, we report a Ti 3 C 2 T x MXene/waterborne polyurethane (WPU) membrane prepared by a vacuum-assisted filtration method, which exhibits excellent THz modulation properties across stretching. The hydrophilic Ti 3 C 2 T x MXene and WPU enable the uniform 3D distribution of Ti 3 C 2 T x MXene in the WPU matrix. Particularly, the stretchability with the maximum strain of the membranes can reach 200%, accompanied by dynamic tuning of THz transmittance for more than 90% and an insertion loss as low as -4.87 dB. The giant THz modulation continuously decreases with MXene content per unit area, accompanied by a lower density of the MXene interface and diminished THz absorption during stretching. Such a design opens a pathway for achieving flexible THz modulators with a high modulation depth and low insertion loss, which would be used for THz flexible and wearable devices.

Cu-based functional materials are excellent candidates for the elimination of iodine anions. However, the low utilization rate of Cu and its unsatisfactory adsorption performance limit its large-scale practical applications. This paper proposes a co-gelation method to obtain Cu/Al 2 O 3 aerogels with a high specific area (537 m 2 /g). Cu/Al 2 O 3 aerogels have a hierarchical porous structure and contain a high proportion of Cu (20.5 wt%). The high dispersibility of Cu, which is based on an in-situ gel process, provides conditions for the high-efficiency elimination of iodide anions. We conducted adsorption experiments that demonstrated that the fabricated Cu/Al 2 O 3 aerogel had an ultrahigh adsorption capacity (407.6 mg/g) and a fast adsorption equilibrium time (0.5 h) for iodide anions. Additionally, the Cu/Al 2 O 3 aerogel could selectively capture iodine anions even in the presence of high concentrations of competing ions (NO 3 - , SO 4 2- , and Cl - at 60 mmol/L). Importantly, the aerogel can operate in a wide pH range of 3-11 without causing secondary pollution. This work demonstrates that low-cost Cu/Al 2 O 3 aerogels exhibit great potential for eliminating radioactive iodine anions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The implementation of Terahertz (THz) modulation is critical for applications in high-speed wireless communications, security screening and so on. Therefore, it is particularly significant to obtain THz wave modulation devices with stable and flexible performance, easy manipulation of the modulation method, and multi-functionality. Here, we propose a flexible all-dielectric metamaterial by embedding zirconia (ZrO 2 ) microspheres into a vanadium dioxide/polydimethylsiloxane (VO 2 /PDMS) composite, which can achieve thermal and mechanical tuning of THz wave transmission. When the temperature of the ZrO 2 /VO 2 /PDMS metamaterial increases, VO 2 changes from the insulating phase to the metallic phase, and the 1 st (at 0.304 THz) and 2 nd (at 0.414 THz) order magnetic resonances exhibit the tunability of 20 GHz and 15 GHz, respectively. When stretched, the 1 st and 2 nd order magnetic resonances show the tunability of 12 GHz and 10 GHz, respectively. In the meantime, there are accompanying changes in transmittance at the resonances. The ZrO 2 /VO 2 /PDMS all-dielectric metamaterial presented in this work provides an alternative strategy for developing actively tunable, flexible, and versatile THz devices. In addition, it has the merits of simple preparation and low cost, promising large-area and rapid preparation of meta-arrays.

The plasmonic shift of resonance wavelength induced by near-field coupling enables one to measure nanoscale distances optically. Empirically, the well-known ruler equation correlating plasmon shift with interparticle spacing was proposed. Though it has been widely used in analyzing simulation and experimental outcomes, little is known about the underlying physical mechanism of the characteristic exponential form of the plasmon ruler equation and the universal decay constant therein. In this work, we attempt to decrypt these from the perspective of plasmon near-field enhancement. Based on an analytical quasi-normal mode formula for plasmon shifts, we proved that the exponential decaying electric field is the critical reason that results in the exponential form of the plasmon ruler equation and quantitatively, we found that the universal decay constant in the plasmon ruler equation actually reflects the range of the enhanced near field. This work hopefully helps to deepen the understanding of the mechanism of light-matter interaction in corresponding plasmonic processes.

Driven by the development of advanced x-ray optics such as Fresnel zone plates, nano-resolution full-field transmission x-ray microscopy (Nano-CT) has become a powerful technique for the non-destructive volumetric inspection of objects and has long been developed at different synchrotron radiation facilities. However, Nano-CT data are often associated with random sample jitter because of the drift or radial/axial error motion of the rotation stage during measurement. Without a proper sample jitter correction process prior to reconstruction, the use of Nano-CT in providing accurate 3D structure information for samples is almost impossible. In this paper, to realize accurate 3D reconstruction for Nano-CT, a correction method based on a feature detection neural network, which can automatically extract target features from a projective image and precisely correct sample jitter errors, is proposed, thereby resulting in high-quality nanoscale 3D reconstruction. Compared with other feature detection methods, even if the target feature is overlapped by other high-density materials or impurities, the proposed Nano-CT correction method still acquires sub-pixel accuracy in geometrical correction and is more suitable for Nano-CT reconstruction because of its universal and faster correction speed. The simulated and experimental datasets demonstrated the reliability and validity of the proposed Nano-CT correction method.

The combination of metasurface and holographic technology is the most cutting-edge development, but most of the proposed designs are static and do not allow active changes through external stimulation after fabrication, which takes only a limited part of the advantage provided by metasurface. Here, we propose and demonstrate a switchable hybrid active metasurface hologram in the terahertz (THz) regime composed of dynamic pixels (VO 2 -CSRR) and static pixels (Au-CSRR) based on an intelligent algorithm, which can display some/all information in different temperature ranges. In particular, such performance shows excellent potential in the field of optical communication security, making it a promising candidate. To prove this possibility, we propose a scheme for optical information encryption/decryption and transmission, which takes metasurfaces as carriers of encrypted information and state/polarization/positions as the secret key components. Only when the two matches correctly can we get the hidden real information. The security of our proposed scheme has reached an unprecedented level, providing a new road for communication security.

Optical physical unclonable function (PUF) is one of the most promising hardware security solutions, which has been proven to be resistant to machine learning attacks. However, the disordered structures of the traditional optical PUFs are usually deterministic once they are manufactured and therefore exhibit fixed challenge-response behaviors. Herein, a reconfigurable PUF (R-PUF) is proposed and demonstrated by using the reversible phase transition behavior of VO 2 nanocrystals combined with TiO 2 disordered nanoparticles. Both the simulation and experiment results show that the near-infrared laser speckle pattern of the R-PUF can be almost completely altered after the phase transition of VO 2 nanocrystals, resulting in a reconfigurable and reproducible optical response. The similarity of the response speckles shows an obvious hysteresis loop during the rise and drop of temperature, providing a simple way to regulate and control the response behaviors of the R-PUF. More importantly, the hysteretic characteristic provides a new dimension to describe the challenge-response behavior of the R-PUF besides the laser speckle, providing an effective way to improve the security and encoding capacity of the optical PUFs. The proposed R-PUF can be employed as a promising security primitive for high robustness and high-security authentication and encryption.

Phase change materials exhibit unique advantages in reconfigurable photonic devices due to drastic tunability of photoelectric properties. Here, we systematically investigate the thermal equilibrium process and the ultrafast dynamics of Ge 2 Sb 2 Te 5 (GST) driven by femtosecond (fs) pulses, using time-resolved terahertz spectroscopy. Both fs-pulse-driven crystallization and amorphization are demonstrated, and the threshold of photoinduced crystallization (amorphization) is determined to be 8.4 mJ/cm 2 (10.1 mJ/cm 2 ). The ultrafast carrier dynamics reveal that the cumulative photothermal effect plays a crucial role in the ultrafast crystallization, and modulation depth of volatile (nonvolatile) THz has switching limits up to 30% (15%). A distinctive phonon absorption at 1.1 THz is observed, providing fingerprint spectrum evidence of crystalline lattice formation driven by intense fs pulses. Finally, multistate volatile (nonvolatile) THz switching is implemented by tuning optical pump fluence. These results provide insight into the photoinduced phase change of GST and offer benefits for all optical THz functional devices.

Dynamic tuning of terahertz (THz) wave is vital for the development of next generation THz devices. Utilization of solar energy for tuning THz waves is a promising, eco-friendly, and sustainable way to expand THz application scenarios. Ti 2 O 3 with an ultranarrow bandgap of 0.1eV exhibits intriguing thermal-induced metal-insulator transition (MIT), and possesses excellent photothermal conversion efficiency. Herein, Ti 2 O 3 film was fabricated by a two-step magnetron sputtering method, and exhibited an excellent photothermal conversion efficiency of 90.45% and demonstrated temperature-dependent THz transmission characteristics with a wideband at 0.1-1 THz. We supposed to combine photothermal conversion characteristics with temperature-dependent THz transmission properties of Ti 2 O 3 film, which could introduce solar light as the energy source for tuning THz waves. Our work will provide new sight for investigating MIT characteristics of Ti 2 O 3 at THz regime and exhibit huge potential in the application of tuning terahertz waves in outdoor scenarios in the future., Competing Interests: The authors declare no competing interests., (© 2021 The Author(s).)

In this work, rapid chemical precipitation assisted annealing method is used to prepare flower-like NiCo 2 S 4 . And the flower-like structure after polyethylene glycol (PEG) modification yields an excellent specific capacitance (2198.9 F g -1 at 1 A g -1 ). And an asymmetric supercapacitor assembled with NiCo 2 S 4 (PEG-modified) and activated carbon (AC) shows an energy density of 38.2 Wh kg -1 at 400 W kg -1 , and outstanding stability (80% remained after 3000 cycles at 5 A g -1 ). Benefited by a larger specific surface area and suitable pore size of the aggregate structure, the specific capacitance of prepared NiCo 2 S 4 is increased by about 2 times. This uncomplicated preparation method is proved to be suitable for NiCo 2 S 4 with a high specific capacitance of supercapacitors.

Purpose: Paired related homoeobox 1 (PRRX1) has been identified as a new epithelial-mesenchymal transition (EMT) inducer in gastric cancer and that PRRX1 upregulation is closely correlated with gastric cancer metastasis. In addition, circulating tumor cells (CTCs) play an important role in the process of gastric cancer's distant metastasis. Our study aimed to correlate Prrx1, CTCs and the clinicopathological parameters in primary gastric cancer patients., Methods: Expressions of PRRX1 in a sample of 95 gastric carcinoma and adjacent nontumorous tissues were detected by immunohistochemistry. Then the integrated subtraction enrichment and immunostaining fluorescence in situ hybridization (SET-imFISH) platform were applied to detect and characterize CTCs in patients with gastric cancer. Finally, their correlations with clinicopathological parameters could be analyzed., Results: The positive rate of PRRX1in gastric cancer was 56.84% and the rate was 36.84% in adjacent normal gastric mucosa, which was confirmed to be statistically significant. In the meantime, both the expression of PRRX1 and the positive rate of CTCs did not significantly correlate with age, gender or histologic type (p>0.05) but significantly related to tumor size, grade of differentiation, lymph node invasion, vascular invasion, metastasis status, depth of tumor invasion, lymph node metastasis and TNM stage (p<0.05). Besides, there was a close relationship between the PRRX1 of gastric cancer and the CTCs of peripheral blood specimens of cancer patients with the correlation coefficient 0.322., Conclusion: Gastric cancer tissues showed that the level of PRRX1 expression was higher compared to the adjacent normal gastric mucosa. Both the expression of PRRX1 and the positive rate of CTCs significantly correlated with clinicopathological parameters. In addition, there was a positive correlation relationship between the PRRX1 of gastric cancer and the CTCs of peripheral blood specimens of cancer patients. These findings demonstrate that higher-level expression of PRRX1 in gastric cancer tissues increased the amount of CTCs in peripheral blood and facilitated the invasion and metastasis in patients with gastric cancer. Meanwhile, it gave some clues to clinical treatment. CTCs may contribute to promotion in diagnosis, therapy monitoring and prognosis of gastric cancer.

Black TiO 2 has received tremendous attention because of its lattice disorder-induced reduction in the TiO 2 bandgap, which yields excellent light absorption and photocatalytic ability. In this report, a highly efficient visible-light-driven black TiO 2 photocatalyst was synthesized with a mesoporous hollow shell structure. It provided a higher specific surface area, more reaction sites and enhanced visible light absorption capability, which significantly promoted the photocatalytic reaction. Subsequently, the mesoporous hollow black TiO 2 with different lattice disorder-engineering degrees were designed. The structure disorder in the black TiO 2 obviously increased with reduction temperature, leading to improved visible light absorption. However, their visible-light-driven photocatalytic efficiency increased first and then decreased. The highest value can be observed for the sample reduced at 350 °C, which was 2-, 1.4- and 5-fold that of the samples reduced at 320 °C, 380 °C and 400 °C, respectively. This contradiction can be ascribed to the varied functions of the surface defects with different concentrations in the black TiO 2 during the catalytic process. In particular, the defects at low concentrations boost photocatalysis but reverse photocatalysis at high concentrations when they act as charge recombination centers. This study provides significant insight for the fabrication of high-efficiency visible-light-driven catalytic black TiO 2 and the understanding of its catalysis mechanism., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

A new simple way for tuning the phase transition temperature (PTT) of VO 2 thin films has been proposed to solve the problem of changing the doping ratio by using the dual-target co-sputtering method. A series of samples with W doping ratios of 0%, 0.5%, 1%, 1.5% and 2% have been fabricated by sputtering V films with the power of pure and 2% W-doped V targets from 500 W: 0 W, 500 W: 250 W, 500 W: 500 W, 250 W: 500 W to 0 W: 500 W respectively and then annealed in an oxygen atmosphere to form VO 2 . The XRD results of both pure and W-doped VO 2 samples reveal that VO 2 forms and is the main component after annealing. The PTT can be tuned by controlling the sputtering power ratio of the pure and doped targets. It can be tuned easily from 64.3 °C to 36.5 °C by using the pure and 2% W-doped targets for demonstration, with W doping ratios from 0% to 2%. It is also valid for other doping elements and is a promising approach for the large-scale production of sputtering.

Ultrafast detection and switching of light are key processes in high-speed optoelectronic devices. However, the performances of VO 2 -based optoelectronics are strongly degraded by photothermal. The mechanism of the latter is still unclear. Here, by using femtosecond-laser (fs-laser) driven kinetic terahertz wave absorption, we quantitatively separate slow photothermal response and ultrafast photodoping response (e.g. light-induced insulator-to-metal transition) from second- to picosecond-timescales, and discover the competing interplay between them. With self-photothermal (mainly determined by fs-laser pulse repetition rate and pump fluence), the ultrafast transition time was degraded by 190% from 50 ps to 95 ps, the ultrafast transition threshold was decreased to 82% from 11mJ/cm 2 to 9mJ/cm 2 , while the amplitudes of the two photoresponse are competing. Percolation theory, along with the macroscopic conductivity response, is used to explain the competing interplay. Our findings are relevant for designing and optimizing VO 2 -based ultrafast optoelectronic devices.

Vanadium dioxide (VO 2 ), with reversible metal-semiconductor transition near room temperature, is a compelling candidate for thermochromic windows. Nanocomposite coatings derived from VO 2 nanoparticles are particularly superior to VO 2 films due to their advantages in large-scale preparation, flexible shaping, and regulation of optical properties. In this work, we developed a novel method for one-step hydrothermal synthesis of W-doped VO 2 (M) nanorods and studied their application in large-scale infrared smart windows. On introducing tartaric acid as a new reductant, VO 2 underwent a two-stage phase evolution from the pure phase comprising VO 2 (A) nanobelts to VO 2 (M) nanorods, instead of the conventional three-stage B-A-M phase evolution during hydrothermal synthesis. This transition is very favorable for the large-scale hydrothermal synthesis of VO 2 (M). The phase-transition temperature of VO 2 (M) nanoparticles can be regulated systematically by W doping, with a reduction efficiency of about 24.52 °C/atom % W. Moreover, VO 2 (M) composite films were fabricated using a convenient roller coating method, which exhibited significant midinfrared transmission switching up to 31%, with a phase-transition temperature of about 37.3 °C. This work demonstrates the significant progress in the one-step hydrothermal synthesis of VO 2 (M) nanorods and provides significant insights into their applications in infrared smart windows., Competing Interests: The authors declare no competing financial interest.

An imaging system based on a polycapillary half-focusing X-ray lens (PHFXRL) and synchrotron radiation source has been designed. The focal spot size and the gain in power density of the PHFXRL were 22 microm (FWHM) and 4648, respectively, at 14.0 keV. The spatial resolution of this new imaging system was better than 5 microm when an X-ray charge coupled device with a pixel size of 10.9 x 10.9 microm was used. A fossil of an ancient biological specimen was imaged using this system.

Analyzer crystal-based computed tomography (ACB-CT) is a novel x-ray phase contrast computed tomography technique. In this paper, in order to extract the refraction angle, we analyzed the effect of misalignment on tomography-sliced images of ACB-CT. Two different methods were considered: the first, proposed by Chapman and Dilmanian, was based on two sets of projective image data taken at both sides of the rocking curve and with a half circle sample rotation and the second, recently proposed by our team, was based on only one set of projective image data taken at one side of the rocking curve but with a full circle sample rotation. Theoretical analysis and experimental results will show that the second method improves the quality of reconstructed CT images, also simplifying the ACB-CT data acquisition procedure.

The significance of the x-ray diffraction enhanced imaging (DEI) technique in the diagnosis of breast cancer and its feasibility in clinical medical imaging are evaluated. Different massive specimens including normal breast tissues, benign breast tumour tissues and malignant breast tumour tissues are imaged with the DEI method. The images are recorded respectively by CCD or x-ray film at different positions of the rocking curve and processed with a pixel-by-pixel algorithm. The characteristics of the DEI images about the normal and diseased tissues are compared. The rocking curves of a double-crystal diffractometer with various tissues are also studied. The differences in DEI images and their rocking curves are evaluated for early diagnosis of breast cancers.

The computed tomography technique cannot easily be extended to diffraction enhanced imaging (DEI) because, while from DEI we may extract the refractive index gradient in one dimension, from the conventional CT reconstruction algorithm we may reconstruct only a scalar quantity. However, recently we showed that changing the direction of the scan axis, and collecting a set of data related to the three-dimensional distribution of the refractive index gradient of the sample, a CT image was obtained. The algorithm we used is based on the conventional CT algorithm but with a specific pre-processing of the projection data. The mathematical framework of the procedure and a simple CT experiment are presented and discussed.

Background: The purpose of this study was to investigate the microstructures of a uterine leiomyoma using a synchrotron-based imaging technique., Material/methods: The tissues of different regions of a uterine leiomyoma were imaged using X-ray diffraction-enhanced imaging., Results: Compared with optical microscopy and conventional X-ray, X-ray diffraction-enhanced imaging can show not only the surface, but also the internal structure of organs or soft tissues with better contrast. Internal hyaline degeneration and the cavum of liquefied uterine leiomyomas are shown very clearly. Some microstructures, such as the myomatous burble, rupture and conglomeration of muscle fiber, and the cavum resulting from red degeneration, can be displayed in X-ray diffraction-enhanced images. These microstructures can show the developmental progress of necrosis in uterine leiomyomas and indicate their potential canceration., Conclusions: X-ray diffraction-enhanced imaging can clearly show internal microstructures of uterine leiomyomas, making the complex procedure of doing this with a large number of pathology slices avoidable.