Hybrid transmission of PS-GS4QAM and QPSK data in the form of a PS-16QAM mm-wave signal enabled by optical asymmetrical dual-SSB modulation.

The independent optical dual-single-sideband (dual-SSB) signal generation and detection can be achieved by an optical in-phase/quadrature (I/Q) modulator and one single photodiode (PD). The dual-SSB signal is able to carry two different information. After PD detection, the optical dual-SSB signal can be converted into an electrical millimeter-wave (mm-wave) signal. Therefore, the optical dual-SSB signal generation and detection technique can be employed in the radio-over-fiber (RoF) system to achieve higher system spectral efficiency and reduce system architecture complexity. However, the I/Q modulator's nonideal property results in the amplitude imbalance of the optical dual-SSB signal, and then the crosstalk can occur. Moreover, after PD detection, the generated mm-wave signal based on the optical dual-SSB modulation has a relatively low signal-to-noise ratio (SNR), which restricts the system performance. In this paper, we propose an optical asymmetrical dual-SSB signal generation and detection scheme based on the probabilistic shaping (PS) technology, to decrease the influence of the optical dual-SSB signal's amplitude imbalance and to enhance the system performance in the scenario of the limited SNR. The dual-SSB in our scheme is composed of the left sideband (LSB) in probabilistic-shaping geometric-shaping 4-ary quadrature amplitude modulation (PS-GS4QAM) format and the right sideband (RSB) in quadrature phase-shift keying (QPSK) format. The transmitter digital signal processing (DSP) generates a dual-SSB signal to drive the optical I/Q modulator. The I/Q modulator implements an electrical-to-optical conversion and generates an optical dual-SSB signal. After PD detection, the optical dual-SSB signal is converted into a PS-16QAM mm-wave signal. In our simulation, compared with the normal 16QAM scenario, the PS-16QAM scenario exhibits a ∼1.2 dB receiver sensitivity improvement at the hard-decision forward error correction (HD-FEC) threshold of 3.8×10-3. Therefore, in our experiment, based on the PS technology, we design a dual-SSB signal including a 5 Gbaud LSB-PS-GS4QAM at -15 GHz and a 5 Gbaud RSB-QPSK at 20 GHz. After 5 km standard single-mode fiber (SSMF) transmission and PD detection, the dual-SSB signal is converted into a 5 Gbaud PS-16QAM mm-wave signal at 35 GHz. Then, the generated PS-16QAM signal is sent into a 1.2 m single-input-single-output (SISO) wireless link. In the DSP at the receiver end, the dual-SSB signal can be recovered from the mm-wave signal, and the PS-GS4QAM and QPSK data carried by the dual-SSB signal can be separated. The bit error rates (BERs) of the LSB-PS-GS4QAM and the RSB-QPSK in our experiment can be below the HD-FEC threshold of 3.8×10-3. The results demonstrate that our scheme can tolerate the I/Q modulator's nonideal property and performs well in the scenario of a relatively low SNR.

Highly Tunable MOF Luminophores Featuring Anthracene Directed Assembly and Fluorescence Regulation.

Metal-organic frameworks (MOFs) have been recognized as a potential platform for the development of tunable luminophores owing to their highly modulable structures and components. Herein, two MOF luminophores based on Cd(II) ions, 1,3,5-tri(4-pyridinyl)benzene (TPB), and 1,4-dicarboxybenzene (H2BDC) were constructed. The directed assembly of the metal ions and organic linkers results in [Cd2(BDC)2(TPB)(H2O)]·x(solvent) (MOF-1) featuring TPB-based blue fluorescence centered at 425 nm. By introducing anthracene as the structure directing agent (SDA) for assembly regulation, [Cd2(BDC)(TPB)2(NO3)2]·x(solvent) (MOF-2) was obtained, which reveals anthracene feeding-dependent high tunable emission in the 517-650 nm range. Detailed components, photophysical properties, and structural characteristics investigations of MOF-2 indicate the TPB and NO3- interactions as the origin of its redshifted emission compared with that of MOF-1. Furthermore, the fluorescence of MOF-2 was found to be regulatable by the anthracene feeding based on the SDA-determined crystallinity of the crystalline sample. All these results provided a unique example of the structural and fluorescence regulation of MOF luminophores.

Modulation of Hierarchical Pores in Metal-Organic Frameworks for Improved Dye Adsorption and Electrocatalytic Performance.

The hierarchical porous metal-organic framework (HP-MOF) has emerged as a hot topic in porous materials in consideration of their advantages in storage capacity and catalysis performance. Herein, we report the construction and property investigation of a series of HP-MOFs. A series of isoreticular microporous MOFs featuring the pacs topology network based on 2,4,6-tris(4-pyridyl)-1,3,5-triazine and different carboxylic acid ligands are found to be potential precursors to construct HP-MOFs. Through the decarboxylation of carboxylate ligands at high temperatures, a hierarchical porous structure could be obtained with the reservation of a crystalline framework. The formation of hierarchical pores is highly dependent on the structural and component nature (carboxylate ligands and metal centers) of the pristine MOF and the pyrolysis conditions (temperature and treatment time), indicating the highly tunable hierarchical pore characteristic of the HP-MOFs. By taking advantage of the increased pore volume and more exposed activation sites, the HP-MOFs reveal enhanced anionic dye adsorption capacity (800 mg·g-1 for Congo red and 140 mg·g-1 for methyl blue) and catalytic activity toward electrocatalytic oxygen reduction reaction (overpotential of 0.302 V at a current density of 10 mA·cm-2, 51 mV lower than that of the pristine MOF).

Defective Hierarchical Pore Engineering of a Zn-Ni MOF by Labile Coordination Bonding Modulation.

The construction and modulation of hierarchical pore structure in metal-organic frameworks (MOFs) has become a hot topic owing to the advantages of hierarchical pore MOFs (HP-MOFs) in matter storage and mass transfer related applications. Herein, we report the engineering of crystalline defect in a bimetallic MOF for the construction and tuning of HP-MOF. A microporous MOF system showing metal-center-dependent water stability, namely, {[M3F(bdc)3 tpt] (solvents)}n (M = Zn2+ and Ni2+, H2bdc = 1,4-benzenedicarboxylic acid, tpt = 2,4,6-tris(4-pyridyl)triazine), was utilized as a platform for the construction of HP-MOF. By tuning the Zn2+/Ni2+ ratio in the reactant, a bimetallic MOF with a highly tunable Zn2+/Ni2+ ratio could be obtained. The relatively labile Zn2+-based coordination bonding in the bimetallic MOF could be readily and targeted broken through water treatment for the engineering of crystalline defects-based hierarchical pore structure. The resultant HP-MOF reveals a dramatically increased pore volume with the presence of mesopore and macropore. In addition, the anionic framework of HP-MOF could be utilized for the selective adsorption of a cationic dye methylene blue, and a relatively high capacity (250 mg·g-1, five times compared with the pristine microporous MOF) could be achieved.

The relationship between sleep quality and occupational well-being in employees: The mediating role of occupational self-efficacy.

Objective: This study aimed to examine the impact of sleep quality on occupational well-being in employees by primarily focusing on the mediating role of occupational self-efficacy. Methods: A total of 487 junior staff completed a set of questionnaires comprised Pittsburgh Sleep Quality Index scale, Occupational Self-efficacy Scale, and occupational well-being measurements. Results: The results revealed that both sleep quality and occupational self-efficacy were significantly correlated with occupational well-being. The structural equation modeling analysis and the bootstrap test indicated that occupational self-efficacy partially mediated the effect of poor sleep quality on occupational well-being. Discussion: These findings expand upon existing research on the relationship between sleep quality and well-being among occupational workers, shed light on the correlation of poor sleep quality with occupational well-being, and are valuable in promoting the occupational well-being of employees.