Unexpected weakened formation of disinfection byproducts and enhanced production of halates by cupric oxide during chlorination of peptide-bound aspartic acid.

Under the condition that the residual chlorine is guaranteed, the biofilm still thrives in drinking water distribution systems through secreting a large number of extracellular polymeric substances (EPS), in which protein components are the primary precursor of disinfection byproducts (DBPs), mostly in the form of combined amino acids. The aim of this study is to investigate the action of CuO on the formation of halates (XO3-, ClO3- and BrO3-) and DBPs (trihalomethanes, THMs; haloacetonitriles, HANs) with aspartic acid tetrapeptide (TAsp) as protein surrogate. The presence of CuO promoted the self-decay rather than TAsp-induced decay of oxidants, resulting in an increase in XO3- yield and a decrease in DBPs yield. It was CuO-induced weaker production of cyanoacetic acid and 3-oxopropanoic acid that induced the decreased yields of HANs and THMs, respectively. The FTIR and Raman spectra indicate a weak complexation between CuO and TAsp. Given this, the CuO-HOX/OX- complexes were inferred to be reactive to HOX/OX- but less reactive to TAsp. The study helps to better understand the formation of XO3- and DBPs during the chlorination of EPS, and propose precise control strategies when biofilm boosts in water pipes.

Nanoprinted Diffractive Layer Integrated Vertical-Cavity Surface-Emitting Vortex Lasers with Scalable Topological Charge.

Vertical-cavity surface-emitting lasers (VCSELs) represent an attractive light source to integrate with OAM structures to realize chip-scale vortex lasers. Although pioneering endeavors of VCSEL-based vortex lasers have been reported, they cannot achieve large topological charges (less than l = 5) due to the insufficient space-bandwidth product (SBP) caused by the inherent limited device size. Here, by integrating a nanoprinted OAM phase structure on the VCSELs, we demonstrate a vortex microlaser with a low threshold and simple structure. A monolithic microlaser array with addressable control of vortex beams with different topological charges (l = 1 to l = 5) was achieved. Nanoprinting offers high degrees of freedom for the manipulation of spatial structures. To address the challenge of insufficient SBP, two-layer cascaded spiral phase plates were designed. Thereby, a vortex beam with l = 15 and mode purity of 83.7% was obtained. Our work paves the way for future chip-scale OAM-based information multiplexing with more channels.

Bioaccumulation and biomagnification of emerging poly- and perfluoroalkyl substances in marine organisms.

Accumulating evidence has demonstrated the wide environmental presence of 6:2 chlorinated polyfluoroalkyl ether sulfonates (6:2 Cl-PFAES) and p-perfluorous nonenoxybenzene sulfonate (PFNOBS). However, data on the bioaccumulation and trophic magnification of these emerging poly- and perfluoroalkyl substances (PFASs) in subtropical marine environment is still limited. In this study, seawater (n = 17), sediment (n = 14), and marine organism (27 species; n = 177) samples were collected from East China Sea, and analyzed them for legacy and emerging PFASs. Besides perfluoroalkyl carboxylates and perfluorooctane sulfonate (PFOS), 6:2 Cl-PFAES was always among the predominant PFASs detected in seawater, sediment, and marine organism. For emerging PFASs, 6:2 Cl-PFAES (mean ± SD, 3.1 ± 0.17), 8:2 Cl-PFAES (3.3 ± 0.35), and PFNOBS (3.3 ± 0.19) had lower bioaccumulation factors (BAF) than PFOS (3.4 ± 0.22) in marine fish. In crab, PFNOBS (3.7 ± 0.33) had a lower biota-sediment accumulation factor (BSAF) than PFOS (3.9 ± 0.45). In snail, among all detected PFASs, PFNOBS (4.0 ± 0.42) had the highest mean log BSAF value. 8:2 Cl-PFAES consistently had a higher log BSAF value than 6:2 Cl-PFAES in snail and crab. Notably, these differences in BAF and BSAF are not significant. Among PFASs, 6:2 Cl-PFAES (2.3; 95 % confidence interval, CI: 1.9-2.6) displayed the highest trophic magnification factor (TMF). PFNOBS had the lowest TMF value (1.8, 95 % CI: 1.4-2.1), but which still indicates its weak biomagnification through the current marine food web. This is the first study reporting the bioaccumulation and biomagnification of PFNOBS in marine organisms, which deepens the understanding of its environmental behavior in the marine ecosystem.

Phthalate metabolites in paired human serum and whole blood.

Presence of phthalate metabolites (PMs) in human serum has been well documented. However, the distribution pattern of PMs in different human blood matrixes remains not well known. To investigate this, paired serum and whole blood samples were collected from 145 adults (76 males and 69 females) in Quzhou, China, and analyzed for nine PMs in this study. All PMs had high detection frequencies (> 70%) in human serum and whole blood, except mono benzyl phthalate. Total concentrations of detected PMs in serum and whole blood were 0.70-61 ng/mL (mean 12 ng/mL) and 1.6-33 ng/mL (7.5 ng/mL), respectively. Mono methyl phthalate (MMP), mono (2-ethylhexyl) phthalate, and mono butyl phthalate were consistently the predominant PMs in human serum and whole blood, with the mean concentrations of 3.4 and 2.0 ng/mL, 3.3 and 2.1 ng/mL, and 2.8 and 1.8 ng/mL, respectively. Females had higher mean serum concentrations of PMs, except MBP, than males. Youngest age group (20-30 years) consistently had the lowest mean whole blood levels of all PMs. For the first time, the distribution pattern of PMs in human blood was evaluated based on the calculated partitioning coefficient (Kp) between serum and whole blood. MMP had the highest mean Kp value (1.6; 10th-90th percentile: 1.0-2.2), while mono (2-ethyl-5-oxohexyl) phthalate had the lowest mean Kp value (0.63; 10th-90th percentile: 0.25-1.3). These results help better understand the occurrence of PMs in human blood.

Nineteen-element in-phase coherent vertical-cavity surface-emitting laser array with low side lobe intensity.

We apply the antenna coherence theory in order to evaluate characteristic behavior of phase-coherent VCSEL arrays. Large 19-element phase-locked VCSEL arrays with a near-diffraction-limited beam were firstly realized using proton implantation technology. The central lobe intensity is about four times that of side lobes in far-field patterns. The angular full width at half maximum (FWHM) of the far field lobes is only 1.42 degrees. A good matching between theory and experiment opens new perspectives for optimizing devices.

Photonics based microwave dynamic 3D reconstruction of moving targets.

In this paper, a photonics based microwave dynamic 3D reconstruction of moving targets is proposed for the first time. The system is based on optical arbitrary waveform generation and photonics assisted 3D imaging processing. An X-band system is established experimentally. A 3D reconstruction of two pairs of cross-placement rotary balls is demonstrated to prove the effectiveness of the proposed system. Experimental results show that the proposed system can provide information on the stereoscopic physical structure of the targets dynamically, being favorable to identification and surveillance of the complex targets.

Reconfigurable photonic microwave convolver for pulse compression of a phase-coded microwave waveform.

A reconfigurable photonic microwave convolver is proposed. The scheme simply consists of the evenly spaced optical carriers (ESOCs), an optical dispersion module (ODM), a wavelength selector (WS), and a balanced photodetector. By adjusting the ESOCs, the dispersion value of the ODM, and the setup of the WS, the proposed convolver is reconfigurable. With the convolver, pulse compressions of the phase-coded microwave waveforms (PCMWs) are realized. Compressions of two PCMWs with different code patterns and respective coding rates of 1.8 and 3.6 Gbit/s are experimentally demonstrated. Full widths at half-maximum (FWHMs) of the main lobe are 0.56 and 0.28 ns, and the peak-to-side lobe ratios are 11.1 and 10.8 dB, respectively. The results are in agreement with the theoretical values. Besides, due to the flexible reconfigurability, it can adapt to various PCMWs by simple operation.

High-resolution W-band ISAR imaging system utilizing a logic-operation-based photonic digital-to-analog converter.

W-band inverse synthetic aperture radar (ISAR) imaging systems are very useful for automatic target recognition and classification due to their high spatial resolution, high penetration and small antenna size. Broadband linear frequency modulated wave (LFMW) is usually applied to this system for its de-chirping characteristic. However, nearly all of the LFMW generated in electronic W-band ISAR system are based on multipliers and mixers, suffering seriously from electromagnetic interference (EMI) and timing jitter. And photonic-assisted LFMW generator reported before is always limited by bandwidth or time aperture. In this paper, for the first time, we propose and experimentally demonstrate a high-resolution W-band ISAR imaging system utilizing a novel logic-operation-based photonic digital-to-analog converter (LOPDAC). The equivalent sampling rate of the LOPDAC is twice as large as the rate of the digital driving signal. Thus, a broadband LFMW with a large time aperture can be generated by the LOPDAC. This LFMW is up-converted to W band with an optical frequency comb. After photonic-assisted de-chirping processing and data processing to the echo, a high-resolution two-dimension image can be obtained. Experimentally, W-band radar with a time-bandwidth product (TBWP) as large as 79200 (bandwidth 8 GHz; temporal duration 9.9 us) is established and investigated. Results show that the two-dimension (range and cross-range) imaging resolution is ~1.9 cm × ~1.6 cm with a sampling rate of 100 MSa/s in the receiver.

Photonics-based wideband distributed coherent aperture radar system.

A photonics-based wideband distributed coherent aperture radar (DCAR) system is proposed and experimentally demonstrated. In the proposed system, the central controlling system and several spatially dispersed remote transceivers are connected by the optical fiber-based time synchronization network. In the central controlling system, the optical-carried orthogonal/coherent linear frequency modulated waveforms (LFMWs) are generated by a reconfigurable multi-channel optical arbitrary waveform generator (RMOAWG), and the signal processing for the echo waves is also implemented there. While in the remote transceivers, only the optical/RF and RF/optical conversions are carried out. Benefitting from the use of photonics-based methods, bandwidths of the generated radar signals can be large, improving the detection resolution of the system. Due to the centralized signal generation and processing, the remote transceivers can be simplified, reducing the system complexity. Moreover, the fiber-based distribution ensures low loss, good transportability, and great flexibility. Experimentally, a two-unit DCAR system operating in X-band with a bandwidth of 3 GHz is presented. When full coherence is achieved, signal-to-noise ratio (SNR) gains of 8.3 dB and 8.33 dB are obtained over a single radar for radar 1 and radar 2, respectively. Results are in good agreement with theoretical prediction. Theoretically, with such SNR gain, the range detection precision can be improved to about 2.6 times that of a single radar.

Photonic generation of multi-frequency phase-coded microwave signal based on a dual-output Mach-Zehnder modulator and balanced detection.

A photonic scheme to generate a multi-frequency phase-coded microwave signal based on a dual-output Mach-Zehnder modulator (DOMZM) and balanced detection is proposed in this paper. The DOMZM driven by an electrical coding data modulates a coherent multi-wavelength light source (CMWL), and a balanced photodetector (BPD) demodulates the output of the DOMZM; as a result, a multi-frequency phase-coded microwave signal is generated. Experiments generate two two-frequency phase-coded signals: one is 5GHz/10GHz signal with a coding rate of 2Gb/s, and the other is 10GHz/20GHz signal with a coding rate of 4Gb/s. Their autocorrelation results show a good pulse compression capability. Each frequency of a two-frequency signal has similar performances with the other in terms of peak-to-side lobe ratio (PSR) and the full width at half-maximum (FWHM) of the main lobe. The proposed scheme can be applied to radar to reduce false detections in adverse conditions. With its potential flexible frequency agility, it can be used for jamming resistance and elimination of the Doppler blind speed during moving target detection.

A submerged membrane bioreactor with pendulum type oscillation (PTO) for oily wastewater treatment: membrane permeability and fouling control.

In this study, a novel submerged membrane bioreactor (SMBR) with pendulum type oscillation (PTO) hollow fiber membrane modules was developed to treat oily wastewater and control the problem of membrane fouling. To assess the potential of PTO membrane modules, the effect of oscillation orientation and frequency on membrane permeability was investigated in detail. The forces exerted on sludge flocs in the oscillating SMBR were analyzed to evaluate the impact of membrane oscillating on the cake layer resistance reduction. Results showed that the optimized PTO SMBR system exhibited 11 times higher membrane permeability and better fouling controllability than the conventional MBR system. By hydrodynamic analysis, it was found that the cooperative effect of bubble-induced turbulence and membrane oscillation in PTO SMBR system generated strong shear stress at liquid-membrane interface in vertical and horizontal direction and effectively hindered the particles from depositing on membrane surface.

Aerobic SMBR/reverse osmosis system enhanced by Fenton oxidation for advanced treatment of old municipal landfill leachate.

A novel combined process of Fenton oxidation, submerged membrane bioreactor (SMBR) and reverse osmosis (RO) was applied as an appropriate option for old municipal landfill leachate treatment. Fenton process was designed to intensively solve the problem of non-biodegradable organic pollutant removal and low biodegradability of leachate, although the removal of ammonia-nitrogen was similar to 10%. After SMBR treatment, it not only presented a higher removal efficiency of organics, but also exhibited high ammonia-nitrogen removal of 80% on average. The variation of extracellular polymeric substance (EPS) content, zeta potential, and particle size of flocs after Fenton effluent continually fed in SMBR was found to be benefit for alleviating membrane fouling. Finally, three kinds of RO membranes (RE, CPA, and BW) were applied to treat SMBR effluents and successfully met wastewater re-utilization requirement. Compared with simple RO process, the troublesome membrane fouling can be effectively reduced in the combined process.

High-performance low-cost organic field-effect transistors with chemically modified bottom electrodes.

The characteristics of organic field-effect transistors (OFETs) were dramatically improved by chemically modifying the surface of the bottom-contact Ag or Cu source-drain (D-S) electrodes with a simple solution method. The contact resistance and energetic mismatch typically observed with Ag D-S electrodes in pentacene bottom-contact OFETs can be properly eliminated when modified by the Ag-TCNQ (TCNQ = 7,7,8,8-tetracyanoquinodimethane). The pentacene transistors with low-cost Ag-TCNQ-modified Ag bottom-contact electrodes exhibit outstanding electrical properties, which are comparable with that of the Au top-contact devices. It thus provides a novel way toward high-performance low-cost bottom-contact OFETs.