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Photocatalysis degradation of tetracycline hydrochloride with high concentration over a hollow microsphere S-doped g-C 3 N 4. [Display omitted] For the past few years, graphitic carbon nitride (g-C 3 N 4) has been widely used to eliminate environmental pollutants, but limited active site on surface and low separation/migration ability suppress its practical uses. Herein, we adopted a supramolecular self-assembly route followed with S doping to synthesize S-doped g-C 3 N 4 with a hollow microsphere composition (SCNHM), where the shell was demonstrated to compose of ultrathin nanosheets. The unique structural characteristics endow the SCNHM with high specific surface area (∼81 m2 g−1) to provide abundant reaction sites and enhanced light-harvesting due to the light-scattering effect of hollow structure. Moreover, the S dopant meliorated the electronic structure to narrow the bandgap and promoted the charge separation/transfer capability. With this synergistic effect, the SCNHM presented greatly improved photocatalytic activity for degrading tetracycline hydrochloride (TC) compared to the CN, SCN and CNHM samples. This photocatalyst could eliminate high-concentration TC (50 mg L−1) in 18 min, and the 30 min removal efficiencies of 100 mg L−1 and 200 mg L−1 reached 92 % and 60 %, which is much better than the reported photocatalysts in literatures (usually ≤ 20 mg L−1). Additionally, the good photocatalytic durability was confirmed and the degradation pathway of TC was proposed. Furthermore, the SCNHM was proved to meanwhile possess superior performance for inactivating the typical Gram-positive bacterium of Staphylococcus aureus (S. aureus) and the typical Gram-negative bacterium of Escherichia coli (E. coli). Finally, based on determination of band alignment and detection of active species, a plausible photocatalytic mechanism was proposed. [ABSTRACT FROM AUTHOR]

Visible-light-driven photocatalytic degradation of moxifloxacin over a aminobenzaldehyde grafted graphitic carbon nitride. [Display omitted] Graphitic carbon nitride (GCN) has been demonstrated to be a potential visible-light-driven photocatalyst for eliminating organic pollutants. However, its practical application is limited by low photocatalytic efficiency originating from high recombination of photogenerated charges. In this work, the electronic structure of GCN was regulated by doping aminobenzaldehyde (ABA) into the skeleton through a solid-state Schiff base reaction. Photoelectrochemical characterizations illustrated that the obtained catalyst (CNABA) exhibited narrower band gap, lower recombination rate of photoinduced electron-hole pair and higher charge transfer ability than the pristine GCN, further indicating its excellent photocatalytic activity. Using moxifloxacin (MOX) as a model pollutant, the ABA doping content was firstly optimized and the optimal activity of the CNABA photocatalyst was 3.1 times higher than that of the GCN. Subsequently, the effects of pH value, photocatalyst dosage and MOX concentration on the photocatalytic behavior were also studied. Superior stability and photocatalytic reusability were confirmed by five repeated tests. By substituting tap water/natural lake water for deionized water and sunlight for xenon light, the CNABA also exhibited high elimination efficiency, implying its good practicability. Superoxide radical, hydroxyl radical and photogenerated hole were identified as the main active species to degrade MOX. Finally, possible degradation pathways for MOX to mineralize small molecules were proposed by determining intermediate products during photocatalysis. This work provides a solid-state method to rationally design aromatic system-modified GCN photocatalysts, and the obtained CNABA is a promising visible-light-driven photocatalyst for eliminating antibiotics. [ABSTRACT FROM AUTHOR]

Visible-light-driven photocatalytic degradation of moxifloxacin over a aminobenzaldehyde grafted graphitic carbon nitride. [Display omitted] Graphitic carbon nitride (GCN) has been demonstrated to be a potential visible-light-driven photocatalyst for eliminating organic pollutants. However, its practical application is limited by low photocatalytic efficiency originating from high recombination of photogenerated charges. In this work, the electronic structure of GCN was regulated by doping aminobenzaldehyde (ABA) into the skeleton through a solid-state Schiff base reaction. Photoelectrochemical characterizations illustrated that the obtained catalyst (CNABA) exhibited narrower band gap, lower recombination rate of photoinduced electron-hole pair and higher charge transfer ability than the pristine GCN, further indicating its excellent photocatalytic activity. Using moxifloxacin (MOX) as a model pollutant, the ABA doping content was firstly optimized and the optimal activity of the CNABA photocatalyst was 3.1 times higher than that of the GCN. Subsequently, the effects of pH value, photocatalyst dosage and MOX concentration on the photocatalytic behavior were also studied. Superior stability and photocatalytic reusability were confirmed by five repeated tests. By substituting tap water/natural lake water for deionized water and sunlight for xenon light, the CNABA also exhibited high elimination efficiency, implying its good practicability. Superoxide radical, hydroxyl radical and photogenerated hole were identified as the main active species to degrade MOX. Finally, possible degradation pathways for MOX to mineralize small molecules were proposed by determining intermediate products during photocatalysis. This work provides a solid-state method to rationally design aromatic system-modified GCN photocatalysts, and the obtained CNABA is a promising visible-light-driven photocatalyst for eliminating antibiotics. [ABSTRACT FROM AUTHOR]

• Degradation of high-concentration(50 mg/L) moxifloxacin. • Methoxybenzoyl was grafted onto g-C 3 N 4. • Electron-withdrawing effect was enhanced. • Excellent photocatalytic stability for multiple uses. Antibiotic residues in water have induced serious environment issues, and semiconductor photocatalysis has been proved as an effective technology for antibiotic elimination. Herein, a post-synthetic strategy was employed to covalently modify g-C 3 N 4 (GCN) with methoxybenzoyl (MOB) via amido bond formation between the terminal amino of GCN and the p -anisoyl chloride. SEM and XRD characterizations indicated the morphologic and structural preservation after MOB modification, and FTIR and XPS results suggested the successful modification of MOB onto the GCN skeleton. Through effectively decreasing the electron cloud density of framework by the amido formation and the grafted MOB, the separation and migration of photogenerated charges were promoted, which were verified by PL and electrochemical measurements. As a result, the MOB/GCN showed greatly improved visible-light-driven photocatalytic activity for MOX degradation compared to the pristine GCN. Reaction parameters, such as synthetic temperature, pH value, photocatalyst dosage and MOX concentration were optimized, and the good photocatalytic durability and applicability in real scenarios were also demonstrated. Finally, the degradation pathway of MOX and the possible mechanism to explain the enhanced photocatalytic performance were proposed. This work demonstrates that covalent modification via the post-synthetic route is a promising approach to meliorate the photocatalytic behavior of GCN. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Songorine isolated from Aconitum brachypodum Diels possesses prominent activity of inhibiting G protein-coupled receptors (GPCRs) in the early screening process. In this paper, a series of Songorine derivatives were synthesized and their inhibitory activities on GPCRs were also evaluated by using the Double Antibody Sandwich ELISA (DAS-ELISA) in vitro. Among them, three derivatives (3a , 4 , 7) exhibited significant inhibitory activity against GPCRs with IC 50 values of 0.08–0.29 nM. Moreover, the structure-activity relationships (SARs) of songorine derivatives were discussed in detail. They have great potentials as novel GPCRs antagonists in the future. [ABSTRACT FROM AUTHOR]

High-repetition-rate nanosecond pulses are used widely in many fields, and pulses of different polarities have different effects. A new pulse-generator structure is proposed based on an improved Blumlein pulse-forming line (BPFL) and a transmission-line transformer (TLT). The proposed structure generates pulses with polarity that can be adjusted among positive, negative, and bipolar. A modular design is used for the generator. In each module, three groups of solid-state switches are used to control the BPFL. By adjusting the timing of the control signal, the BPFL can generate high-repetition-rate nanosecond primary pulses with adjustable polarity. These primary pulses are then transmitted to the load through the TLT with amplification and superposition. The pulse-forming process is analyzed theoretically for matched impedance. The strategy for controlling the switches is also illustrated. In addition, the feasibility of the proposed generator is verified by simulations and experiments. Finally, a four-stage prototype is developed that can produce pulses with amplitudes of 0–10 kV, a width of 30 ns, repetition rates up to 200 kHz and adjustable polarity. [ABSTRACT FROM AUTHOR]

A high pulse repetition frequency (PRF) nanosecond pulse generator based on Blumlein pulse forming line (BPFL) and transmission line transformer (TLT) is proposed in this paper. The generator combines the BPFL characteristic, which is used to generate a narrow, high PRF pulse, with the excellent performance at high frequency of a transmission line transformer. A modular structure was adopted for this design. The primary pulse produced by the BPFL in each module will output to the load through the TLT amplifier; further, the output of multiple modules can be cascaded to improve the load voltage and output power. Moreover, this reduces the ratio of the output impedance and the input impedance of the TLT, making the generator more suitable for light loads. A microstrip line was used for the transmission line, which makes it possible to match random loads. Additionally, the size of generator was greatly reduced to realize a compact design. MOSFETs were used in the generator to facilitate the control of both the amplitude and PRF of the output. A two-stage laboratory prototype was fabricated to verify the performance of the proposed topology. As a result, the generator produced pulses for matched loads with amplitudes of 0?2.5 kV, pulse width of 20 ns, and repetition frequencies of 0?10 kHz. The generator can be used as a hardware foundation for research on the biomedical effects of exposure to high PRF nanosecond pulse electric fields. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: A divergent and novel protocol for the preparation of both pyrido[2,3,4‐kl]acridine and pyrido[4,3,2‐kl]acridine alkaloids was developed. This method featured the remote palladium‐catalyzed reductive cyclization with Mo(CO)6 as reductant. A wide range of substrates including three types of nitro arenes were tolerated and afforded corresponding products in good to excellent yields. This method has been successfully applied to the total synthesis of norsegoline, styelsamine C and the skeleton of necatorone. [ABSTRACT FROM AUTHOR]

The rise/fall time of a high-voltage nanosecond pulse affects the application effect of the pulse; therefore, it is of great significance to study the adjustment of the rise/fall time. In this paper, a new type of generator topology based on a half-bridge modular multilevel converter (HB-MMC) is proposed that uses MOSFETs as solid-state switches to produce a unipolar/bipolar high-voltage nanosecond pulse with an adjustable rise/fall time. The proposed topology consists of 2 arms, each of which contains several HB-MMC submodules. The capacitors of each arm are charged with a positive voltage and negative voltage in parallel. By controlling the discharging sequence of the two arms, a unipolar or bipolar pulse can be generated. For each arm, by setting the switching sequence of the MOSFETs, the number of capacitors inserted into the discharging circuit can be controlled to allow a multilevel pulse to be generated. The rise/fall time of the output pulse can be adjusted by changing the number of levels and the duration of each level. Detailed illustrations of the proposed configuration and its operational concept are presented. Experimental results for a scaled-down prototype are presented to validate the concept. [ABSTRACT FROM AUTHOR]

Magnetic pulse compression (MPC) systems are suitable for generating dielectric barrier discharges (DBDs) owing to their capability of producing high-amplitude, short pulse voltage waves. This paper proposes a high-frequency, bipolar magnetic compression system to study DBD plasma characteristics. First, the principle of bipolar MPC is explained [a bipolar MPC system comprises a full bridge inverter circuit, pulse transformer (PT), and magnetic switch (MS)]. Additionally, the design of the PT and MS is described. Then, the waveform of the resistive load is tested and compared with PSpice simulation results. It was found that the nanosecond pulse generator produces a pulse on a resistor with an amplitude of 0–13 kV, a rise time of approximately 100 ns, and a repetition frequency of 0 to several kHz. Finally, this paper studies the plasma characteristics under the application of a high-frequency bipolar pulse, and the charge–voltage Lissajous figure of the discharge waveform is analyzed. Combining discharge photographs and theoretical calculation results yields the relationship between the discharge characteristics and the frequency, which enriches the theoretical study of high-frequency bipolar discharges. [ABSTRACT FROM AUTHOR]

Several series and parallel Blumlein-type striplines designed on multilayered printed circuit board (PCB) are connected to match different impedance loads with different pulsewidths to develop a high-voltage nanosecond pulse generator for investigating the biological effects of a nanosecond pulsed electric field. First, the principle of a multistage series–parallel Blumlein stripline system is described. In particular, the multilayered strip transmission line is designed on the five-layered PCB to minimize the volume of the system whose maximum size is 300 mm (length) $\times \,\, 260$ mm (width) $\times \,\, 154$ mm (height), and the gate resistor capacitor and diode active equalizing circuit is used as the dynamic/static balancing tactic. Then, a single-stage Blumlein-type stripline and some multistage series–parallel Blumlein-type stripline are established to test their performance. As a result, the nanosecond pulse generator produces a rectangular pulse on a matched resistor load, with an amplitude of 0–1.7 kV, a pulsewidth of integer multiples of 100 ns, a rise time of $\sim 20$ ns or less, and a repetition frequency of 0 to several kHz. A variety of biomedical loads can be matched by parallel stacking mode, which will facilitate the analysis of the biological effects of the nanosecond pulsed electric field. [ABSTRACT FROM AUTHOR]

This paper introduces unipolar high-frequency nanosecond pulse bursts, which combine the advantages of microsecond pulsed electric fields and nanosecond pulsed electric fields, for the treatment of tumors. To take full advantage of this nonthermal pulsed electric field treatment, it is necessary to study the thermal effects of the high-electric-field nanosecond pulse bursts inside tumor tissue. A multiparametric analysis is performed based on a finite-element model of skin with a melanoma tumor that is nipped using the Tweezertrodes. The electric field ranges from 1 to 10 kV/cm, the pulsewidth ranges from 50 to 500 ns, and the frequency in the pulse bursts ranges between 100 kHz and 1 MHz. The total pulselength is $100~\mu \text{s}$ , and the frequency of the pulse bursts is 1 Hz. The Pennes bioheat transfer equation and the Arrhenius equation are used to calculate the temperature and the thermal damage. For pulse parameters of 5 kV/cm, 500 ns, and 1 MHz, the simulated temperature of the skin tumor is only 37.48 °C after 1 s, and the thermal damage is negligible. The temperature and thermal damage to the melanoma tumor in the skin are simulated and calculated for various electric fields, pulse widths, and frequencies. The relationship between the thermal effects on the tumor and the pulse parameters is researched, and pulse parameters for a tumor without thermal damage are ascertained. Temperature measurements of melanoma tumors in nude mice in vivo show that the change in experimental temperature in the tumors is consistent with the simulated average tumor temperature. [ABSTRACT FROM AUTHOR]

High-frequency nanosecond-pulsed electric fields were recently introduced for tumor or abnormal tissue ablation to solve some problems of conventional electroporation. However, it is necessary to study the thermal effects of high-field-intensity nanosecond pulses inside tissues. The multi-parametric analysis performed here is based on a finite element model of liver tissue with a tumor that has been punctured by a pair of needle electrodes. The pulse voltage used in this study ranges from 1 to 4 kV, the pulse width ranges from 50 to 500 ns, and the repetition frequency is between 100 kHz and 1 MHz. The total pulse length is 100 μs, and the pulse burst repetition frequency is 1 Hz. Blood flow and metabolic heat generation have also been considered. Results indicate that the maximum instantaneous temperature at 100 µs can reach 49 °C, with a maximum instantaneous temperature at 1 s of 40 °C, and will not cause thermal damage during single pulse bursts. By parameter fitting, we can obtain maximum instantaneous temperature at 100 µs and 1 s for any parameter values. However, higher temperatures will be achieved and may cause thermal damage when multiple pulse bursts are applied. These results provide theoretical basis of pulse parameter selection for future experimental researches. [ABSTRACT FROM AUTHOR]

To carry out cell experiments for the pulsed magnetic field treatment of tumor cells, a high dB/dt pulsed magnetic field generator based on a printed circuit board (PCB) Archimedes spiral coil and a self-breakdown air switch is developed. The magnetic field and the induced electric field around the Archimedes spiral coil are calculated. Using COMSOL Multiphysics software, the magnetic field distribution characteristics of the coil are optimally designed. Then, the performance of the generator is measured. Ultimately, the PCB Archimedean spiral coil has seven turns, and it has a diameter of 21 mm. The coil can produce the following pulse magnetic field parameters in a cell culture liquid: an amplitude of 0.92 T, a rise time of 78 ns, a pulsewidth of 1.8 \mu \text{s} , a rate of magnetic field change that reaches 1.1\times 10^{7} T/s, a maximum-induced electric field of 55.9 kV/m, a degree of electric field uniformity of 84%, and a maximum-induced current density of 1.7 \times 10^4 A/ \textm^2 . The coil can be used to deliver pulsed magnetic field and induced electric field to biological objects. [ABSTRACT FROM AUTHOR]