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Based on the hard and soft acid and base (HSAB) theory, three heterometallic uranyl organic frameworks (UOFs), namely, [Zn(UO2)(npa)2(2,2′-bpy)(H2O)] (1), [Zn(UO2)(nip)2(2,9-dm-1,10-phen)] (2), and [Zn(UO2)(ntp)2(4,7-dm-1,10-phen)(H2O)]·(H2O) (3), have been solvothermally synthesized by using a variety of different substituted nitro-benzenedicarboxylic acid (H2npa = 3-nitrophthalic acid, H2nip = 5-nitroisophthalic acid, H2ntp = 2-nitroterephthalic acid) and uranyl zinc acetate, in the presence of N-bearing coligands, including 2,2′-bipyridine (2,2′-bpy), 2,9-dimethyl-1,10-phenanthroline (2,9-dm- 1,10-phen), and 4,7-dimethyl-1,10-phenanthroline (4,7-dm-1,10-phen). The results of single-crystal X-ray diffraction analysis show that each of them presents a heterometallic interaction between the uranyl and Zn2+centers. UOFs 2and 3adopt three-dimensional (3D) frameworks with different architectures, while UOF 1exhibits a one-dimensional (1D) chain assembly. Furthermore, 1can be used as a bifunctional luminescent sensor for the detection of metamitron (MMT) and Cr2O72–in aqueous solution with the limit of detection (LOD) for 4.06 × 10–6and 2.52 × 10–6M, respectively. The sensing mechanism was also investigated in detail through ultraviolet–visible (UV–vis) absorption spectroscopy, density functional theory calculations (DFT), and fluorescence lifetime analysis. This work provides valuable guidance for the facile and effective design and construction to employ UOFs as multiresponsive fluorescence sensors for the detection of environmental pollutants in aqueous solution.

The physical layer secret key generation exploiting wireless channel reciprocity has demonstrated its viability and effectiveness in various wireless scenarios, such as the Internet of Things (IoT) network, mobile communication network, and industrial control system. Most of the existing studies rely on the quantization technique to convert channel measurements into secret bits for confidential communications. However, non-simultaneous packet exchanges in time-division duplex systems and noise effects usually induce inconsistent quantization results and mismatched secret bits. Although recent research has spent significant effort mitigating such non-reciprocity, it is still far from practical error-free key generation. Unlike previous quantization-based approaches, we take a different viewpoint to match the randomly manipulated (i.e., permuted or edited) channel measurements between a pair of users by minimizing their discrepancy holistically. Specifically, two novel secret key generation algorithms based on bipartite graph matching (BM-SKG) and edited sequence alignment (SA-SKG) are developed. BM-SKG allows two users to generate the same secret key based on the permutation order of channel measurements, while SA-SKG aims to align the edited channel measurements between a pair of users for secret key agreement. In both algorithms, one user can preset the secret key and embed encrypted messages in the exchanged data packets, which reduces communication overheads in key generation. Extensive experimental results show that both BM-SKG and SA-SKG algorithms achieve error-free key agreement on channel measurements at a low cost under various scenarios.

Under solvothermal conditions, three 3D lanthanide metal–organic frameworks (Ln-MOFs): [Eu(H2DHTA)1.5(DMF)2]·DMF (1), [Eu(H2DHTA)0.5(DHTA)0.5(DMF)(H2O)]·2H2O (2), and Eu(HCOO)3(3) (H4DHTA = 2,5-dihydroxyterephthalic acid) have been synthesized by different reaction times. Interestingly, induced by reaction time, compounds 1–3underwent a two-step dissolution and recrystallization structural transformation (DRST) reaction. Investigations on the DRST processes were carried out, and the transformation pathway was deduced, which was verified by XRD analyses. Notably, compound 2demonstrates pronounced luminescence as well as high stability in water and other organic solvents. The fluorescent detection of furan antibiotics can serve as turn-off effects, and glutamic acid (Glu), aspartic acid (Asp), and riboflavin (VB2) can serve as the turn-on effect. To explain the enhancing and quenching mechanisms, XRD, UV–visible absorption spectroscopy, electrochemistry, IR spectra, theoretical calculation, fluorescence lifetimes, and XPS were discussed. Additionally, MOF-coated test strips were utilized to detect these analytes, exhibiting excellent agreement with fluorescence spectroscopy. This work provides an example for more effective designs to employ Ln-MOFs as multiresponsive fluorescent sensors for detection of environmental pollutants in aqueous solution.

Physical-layer key generation has emerged as a promising avenue for establishing secret keys using reciprocal channel measurements between wireless devices. However, channel reciprocity may suffer degradation from ambient noise and cause mismatched secret bits, while existing methods mitigating this issue may yet face limitations in key efficiency. The root cause behind such limitations is the heavy reliance on channel measurements, which can be naturally susceptible to channel non-reciprocity attributed to environmental factors. Instead of direct key extraction from channel measurements, we seek to share a pre-defined key and utilize channel measurements as a bearer to facilitate key transmission. We propose an accurate and efficient key generation method (KeyCome) to ensure secure key sharing by encapsulating it with channel state information (CSI) obfuscation matrices through circulant convolution. To this end, we develop a reliable key derivation through a quadratic programming method with matrix equilibration, ensuring stable and rapid solutions. Notably, the transmitter can control the key beforehand for enhanced communication efficiency and combine it with an error correction mechanism for accurate key derivation. Furthermore, a lightweight reconciliation scheme is designed to minimize mismatched bits caused by occasional non-reciprocity. Comprehensive experiments demonstrate KeyCome's high accuracy and efficiency in key generation.

During the operation of the Chinese 250 km/h-level EMU, hunting occurs when the EMU crosses from Line B to Line A. Numerous tests and simulations have been conducted to investigate the mechanism of this phenomenon. Comparisons of the measured rail profiles of the two lines indicate that the left rail in Line A is higher than that in Line B at the inner rail shoulder. In addition, the top position of the right rail in Line A is approximately 2–3 mm closer to the inside than that of the right rail in Line B, with the right rail in Line A being higher than that in Line B at the inner rail shoulder. These differences cause a significant increase in the wheel–rail equivalent conicity when the EMU crosses from Line B to Line A and further cause the hunting phenomenon. Moreover, simulations and experiments are conducted to investigate the countermeasures for EMU cross-line hunting. Field test results show that both increasing the damping of the yaw damper and wheel reprofiling can improve the stability during EMU cross-line operation; however, the effect of increasing the damping of the yaw damper is limited under particularly poor wheel–rail relationship. Simulation results reveal that rail grinding of Line A referring to the Chinese 60N rail profile can also improve the stability of the EMU during cross-line operation.