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Small-molecule organic photovoltaic materials attract more attention attributing to their precisely defined structure, ease of synthesis, and reduced batch-to-batch variations. The majority of all-small-molecule organic solar cells (ASM-OSCs) have traditionally relied on halogenated solvents for dissolving photovoltaic materials as well as used for the additives or solvent vapor annealing. However, these halogen-based processes pose risks to the environment and human health, potentially impeding future commercial production. Herein, we conducted an investigation into the impact of various nonhalogen solvents on the performance of the devices. By selecting the high boiling point solvent toluene, we achieved a desirable phase separation and stable morphology characterized by fibrous crystals within the blend film. Consequently, the power conversion efficiencies of 14.4 and 11.7% were obtained from H31:Y6-based small-area (0.04 cm2) and large-area (1 cm2) devices with steady performance, respectively. This study successfully demonstrated the fabrication of ASM-OSCs without employing halogenated solvent processes, thus offering promising prospects for the commercial production of ASM-OSCs.

Base station (BS) activation is a widely-used approach to alleviate the system power cost for device maintenance. However, frequently switching on/off BSs may also introduce extra power and signaling costs, which motivates us to limit the BS switching frequency when performing BS activation. To address this, we study a problem of joint long-term BS activation and short-term beamforming (J-LTBA-STBF) in a network where multiple multi-antenna BSs cooperatively serve multiple single-antenna users. LTBA means that each BS’s active/inactive switching frequency is properly controlled to yield relatively stable BS-user association and limited switching power, while STBF lies in that due to the low cost of refreshing beamformers, the transmit beamformers are allowed to be updated frequently to maximally lower the transmit power. Following the idea, two efficient algorithms are designed, according to the data amount they request to start running, to optimize the active BSs and the BS transmit beamformers in multiple adjacent time slices. Consequently, the transmit, maintenance and switching powers can be well balanced to facilitate power-efficient communications. Numerical results validate the efficacies of the algorithms.

Hybrid beamforming (HBF) is a key enabler for wideband terahertz (THz) massive multiple-input multiple-output (mMIMO) communications systems. A core challenge with designing HBF systems stems from the fact their application often involves a non-convex, highly complex optimization of large dimensions. In this article, we propose HBF schemes that leverage data to enable efficient designs for both the fully-connected HBF (FC-HBF) and dynamic sub-connected HBF (SC-HBF) architectures. We develop a deep unfolding framework based on factorizing the optimal fully digital beamformer into analog and digital terms and formulating two corresponding equivalent least squares (LS) problems. Then, the digital beamformer is obtained via a closed-form LS solution, while the analog beamformer is obtained via ManNet, a lightweight sparsely-connected deep neural network based on unfolding projected gradient descent. Incorporating ManNet into the developed deep unfolding framework leads to the ManNet-based FC-HBF scheme. We show that the proposed ManNet can also be applied to SC-HBF designs after determining the connections between the radio frequency chain and antennas. We further develop a simplified version of ManNet, referred to as subManNet, that directly produces the sparse analog precoder for SC-HBF architectures. Both networks are trained with an unsupervised procedure. Numerical results verify that the proposed ManNet/subManNet-based HBF approaches outperform the conventional model-based and deep unfolded counterparts with very low complexity and a fast run time. For example, in a simulation with 128 transmit antennas, ManNet attains a slightly higher spectral efficiency than the Riemannian manifold scheme, but over 600 times faster and with a complexity reduction of more than by a factor of six (6).

Secrecy rate (SR) optimization in millimeter wave (mmWave) Internet of Things (IoT) systems with simultaneous wireless information and power transfer (SWIPT) is studied in this article. Adopting the SWIPT architecture, energy-constrained devices get charged by the radio-frequency waves transmitted from a base station. The hybrid precoding technique is applied to reduce the implementation cost by separately designing a digital precoder and an analog precoder. Also, we adopt the artificial noise (AN)-assisted transmission method to maximize the SR. In this problem, we aim to jointly optimize the digital precoding vector, AN covariance matrix, and power-splitting ratio under the nonlinear energy harvesting (EH)-constraints. Then, we propose a semidefinite relaxation-based alternating optimization algorithm for the case of perfect channel state information (CSI) and imperfect CSI. Finally, simulation results show that the proposed algorithms are effective to improve the SR.

The simultaneous application of photothermal therapy (PTT) and photodynamic therapy (PDT) offers substantial advantages in cancer treatment. However, their synergistic anticancer efficacy is often limited by tumor hypoxia, and thermotolerance induced by high expression of heat shock proteins (HSP). Fortunately, hydrogen sulfide (H2S), known for its direct cytotoxic effect on tumor cells, has been recognized for its ability to enhance PTT and PDT. The effectiveness of H2S in these therapies is challenged by its low loading efficiency, poor stability, and short diffusion distance. To address these issues, a nanoscale emulsion drop template created through the salting‐out effect is employed to construct a robust H2S delivery system. Polydopamine (PDA), chosen for its interfacial polymerization tendency and excellent photothermal conversion rate, is utilized as a carrier for the H2S donor (ADT) and Zinc phthalocyanine (ZnPc) to fabricate a novel nanomedicine termed APZ NPs. The temperature‐responsive APZ NPs are designed to release H2S during the PTT process. Elevated H2S levels promoted vasodilation, thereby enhancing the enhanced permeability and retention effect (EPR) of APZ NPs within solid tumors. This strategy effectively alleviated tumor hypoxia by disrupting the mitochondrial respiratory chain and mitigated tumor cell heat tolerance by inhibiting HSP expression. A novel and simple emulsion droplet template is prepared based on the salting‐out effect, and the hollow PDA is fabricated using the template. Furthermore, hollow PDA is designed as carriers for H2S donors and ZnPc to fabricate APZ NPs. APZ NPs can inhibit HSP protein expression and alleviate tumor hypoxia for enhancing the synergetic PTT and PDT anticancer efficacy.

Due to the unique properties of two-dimensional (2D) materials, much attention has been paid to the exploration and application of 2D materials. In this review, we focus on the application of 2D materials in mode-locked fiber lasers. We summarize the synthesis methods for 2D materials, fiber integration with 2D materials and 2D materials based saturable absorbers. We discuss the performance of the diverse mode-locked fiber lasers in the typical operating wavelength such as 1, 1.5, 2 and 3 μm. Finally, a summary and outlook of the further applications of the new materials in mode-locked fiber lasers are presented.

In this article, a high-quality saturable absorber (SA) based on a two-dimensional ternary chalcogenide Ta2NiS5nanosheet has been successfully fabricated and used in 1- and 1.5-μm spectral regions to generate ultrafast laser pulses. The Ta2NiS5-based SA is fabricated by mechanical exfoliation and sandwiched between two fiber ferrules to form a fiber-compatible SA. On the basis of the twin-detector technique, nonlinear optical absorption of the Ta2NiS5-SA is characterized by 64.7% and 11.95% modulation depths with 1.3 and 0.72 MW/cm2saturation intensities at 1028 and 1570 nm, respectively. When Ta2NiS5-SA is integrated into Yb- and Er-doped fiber laser cavities, stable self-starting Q-switched pulses are observed. Furthermore, by adjusting the cavity structure and optimizing dispersion in the cavity, we obtain hybrid mode-locking and mode-locking fiber laser operation at 1029 and 1569 nm, respectively. These results validate the performance of Ta2NiS5as a broadband SA for the generation of ultrafast laser pulses, offering new opportunities of ternary transition-metal dichalcogenide alloys in future photonic devices.

Urea-formaldehyde resin (UFR) wastewater containing formaldehyde (FA) and urea generated from UFR production and utilization is harmful to humans and the environment. To improve the energy efficiency of treating toxic UFR wastewater without generating secondary pollution, a novel low-aeration-pressure plate membrane-aerated biofilm reactor (PMABR) was developed, and a combined system composed of a PMABR and a biological aerated filter (BAF) was constructed. In the combined system, the PMABR realized FA conversion and urea hydrolysis, the ammonium nitrogen (NH4+-N) in the PMABR effluent was efficiently nitrified in the BAF, and the intermediate products methanol and volatile fatty acids (VFAs) in the PMABR were used as organic carbon sources to denitrify nitrate nitrogen (NO3−-N). When the membrane aeration pressure was 0.50 kPa and the influent pollutant membrane area loadings of PMABR were 11.24 g FA/(m2d) and 11.98 g urea/(m2d), the removal rates of FA, chemical oxygen demand (COD) and total nitrogen (TN) in the combined system reached 100%, 96.68% and 81.84%, respectively. The low-aeration-pressure PMABR largely reduced aeration energy consumption and provided an organic carbon source and environmental conditions for denitrification. The combination of a PMABR and a BAF can realize the cleaner treatment of toxic UFR wastewater in an economical manner.

In this paper, we demonstrate excellent ultrafast optical performance of ternary transition metal dichalcogenide ReS1.02Se0.98 saturable absorber with high power tolerance and large modulation depth in thulium-doped fiber laser. Q-switching with tunable repetition frequency and pulse duration, and mode-locking with high pulse energy were generated in our experiment. The average output power/pulse energy/pulse duration of the mode-locked pulse train were 313 mW/13.6 nJ/1.43 ps, respectively.