Unraveling the strain tuning mechanism of interlayer excitons in WSe2/MoSe2heterostructure.

Atomically thin transition metal dichalcogenides (TMDs) exhibit rich excitonic physics, due to reduced dielectric screening and strong Coulomb interactions. Especially, some attractive topics in modern condensed matter physics, such as correlated insulator, superconductivity, topological excitons bands, are recently reported in stacking two monolayer (ML) TMDs. Here, we clearly reveal the tuning mechanism of tensile strain on interlayer excitons (IEXs) and intralayer excitons (IAXs) in WSe2/MoSe2heterostructure (HS) at low temperature. We utilize the cryogenic tensile strain platform to stretch the HS, and measure by micro-photoluminescence (µ-PL). The PL peaks redshifts of IEXs and IAXs in WSe2/MoSe2HS under tensile strain are well observed. The first-principles calculations by using density functional theory reveals the PL peaks redshifts of IEXs and IAXs origin from bandgap shrinkage. The calculation results also show the Mo-4d states dominating conduction band minimum shifts of the ML MoSe2plays a dominant role in the redshifts of IEXs. This work provides new insights into understanding the tuning mechanism of tensile strain on IEXs and IAXs in two-dimensional (2D) HS, and paves a way to the development of flexible optoelectronic devices based on 2D materials.

Low-loss microwave photonic switching for satellite communication.

For traditional switching architecture, packet switching performs fine granularity data packet forwarding, but its digital signal processing (DSP) has high power consumption (PC). All-optical switching provides rapid exchange of wavelength resources, which has coarse granularity. In scenarios where the PC is limited, such as broadband satcom, a switching architecture with lower PC and finer granularity than optical switching would be useful. In this paper, we propose a novel, to the best of our knowledge, low-loss microwave photonic switching architecture that can exchange subband signals across beams and frequency bands. The switching process is realized by exchanging optical carriers instead of payload signals, which does not degrade the signal power, guaranteeing the signal-to-noise ratio (SNR). We conducted a proof-of-concept experiment of 2 × 2 switching with two 1.2-GBaud quadrature phase-shift keying (QPSK) signals; an error vector magnitude (EVM) of or less than 13.87% is realized after forwarding. The proposed system has the advantages of low PC, high SNR, and fine granularity, and is very promising for flexible forwarding in future satcom systems.

Broadband dual-channel channelizer based on a microwave photonic power tunable image rejection down-conversion.

Radiofrequency (RF) channelization has potential high frequency and wideband advantages in frequency-domain channel segmentation and down-conversion reception. In this paper, we propose a compact dual-channel channelizer that can process high-frequency wideband signals. It uses double-polarization double-sideband electro-optic modulation and Hartley structure photoelectric conversion to realize down-conversion channelization of the high-frequency wideband signal. The power matching between two polarization signals can be realized by controlling the modulator bias, so the crosstalk between the two output signals can be suppressed. The proposed channelizer has a compact structure since the electro-optic modulation is based on one single laser and one single integrated modulator. No filters are used in the structure, contributing to a very wide RF operation bandwidth and low constraints of laser wavelength. In the experiment, the single frequency signal pairs from 9 GHz to 15 GHz can achieve an inter-channel image rejection ratio of 53 dB. Furthermore, the channelizer slices multi-octave bandwidth quadrature phase shift keying (QPSK) signals up to 16 GHz with the wideband isolation higher than 10 dB and outputs them to two channels in parallel. The error vector magnitudes (EVM) of 9-17 GHz and 18-26 GHz band QPSK signals are guaranteed to be under 23.58% after channelized separation. To the best of our knowledge, the proposed channelizer provides high inter-channel interference suppression at dual-band adjacent signals with 8 GHz bandwidth for the first time. Therefore, the proposed channelizer has great application value for the reception and processing of millimeter signals in the future.

Low-cost micro-spectrometer based on a nano-imprint and spectral-feature reconstruction algorithm.

Reconstructive micro-spectrometers have shown great potential in many fields such as medicine, agriculture, and astronomy. However, the performance of these spectrometers is seriously limited by the spectral varieties of response pixels and anti-noise ability of reconstruction algorithms. In this work, we propose a spectral reconstruction (SR) algorithm, whose anti-noise ability is at least four times better than the current algorithms. A micro-spectrometer is realized by fabricating a large number of Fabry-Perot (FP) micro-filters onto a cheap complementary metal-oxide semiconductor (CMOS) chip for demonstration by using a very high-efficiency technology of nano-imprinting. Nano-imprint technology can complete hundreds of spectral pixels with rich spectral features at one time and with low cost. In cooperation with the SR algorithm, such a micro-spectrometer can have a spectral resolution as high as 3 nm with much lower angular sensitivity than a photonic crystal-based micro-spectrometer. It can obtain the target's spectrum from only a single shot, which has wide applications in spectral analysis etc.

Erbium chloride silicate-based vertical cavity surface-emitting laser at the near-infrared communication band.

Silicon-based integrated optoelectronics has become a hotspot in the field of computers and information processing systems. An integrated coherent light source on-chip with a small footprint and high efficiency is one of the most important unresolved devices. Here, we realize a silicon-based vertical cavity surface-emitting laser in the near-infrared communication band by making efforts in both controlled preparation of high-gain erbium silicate materials and novel design of high optical feedback microcavity. Single-crystal erbium/ytterbium silicate microplates with erbium concentration as high as 5 × 1021 cm-3 are controlled prepared by a chemical vapor deposition method. They can produce strong luminescence with quite a long lifetime (2.3 ms) at the wavelength of 1.5 µm. By embedding the erbium silicate microplates between two dielectric Bragg reflectors, we construct a vertical cavity surface-emitting laser at 1.5 µm, with a lasing threshold as low as 20 µJ/cm2 and Q factor of nearly 2000. Our study provides a new pathway to achieve a sub-micrometer coherent light source for optical communication.

Realization of strong coupling between 2D excitons and cavity photons at room temperature.

Two-dimensional (2D) semiconductors of graphene, as well as transition-metal dichalcogenides, have performed strong interaction with light. Here the strong light-matter interaction between monolayer tungsten disulphide (WS2) excitons and microcavity photons at room temperature is well studied by the introduction of a gain material embedded dielectric optical microcavity structure. A Rabi splitting of about 36 meV is observed in angle-resolved reflectance spectra at room temperature, which agrees well with the theoretical results simulated by using the transfer matrix method. Since the cavity structures and 2D semiconductors can be prepared, the cavity and the gain materials, respectively, can be optimized separately in this platform. An all-dielectric Fabry-Pérot microcavity provides a simple but effective way to study the room temperature strong coupling between cavity photons and 2D excitons.

Association of Subclinical Thyroid Dysfunction with Chronic Kidney Disease: A Systematic Review and Meta-analysis.

Background: The association of subclinical thyroid dysfunction (SCTD) with chronic kidney disease (CKD) among community population remains inconclusive. Our aim was to evaluate the association between SCTD and the risk of CKD by conducting a meta-analysis.Methods: Multiple databases were searched to identify studies on the association between SCTD and risk of CKD, up to October 2018. Relevant information for analysis was extracted. A random-effects model was used to calculate the pooled risk estimate.Results: Eight articles were included in this meta-analysis, with three cohort and five cross-sectional studies. The pooled odds ratio (OR) of subclinical hypothyroidism for CKD was 1.37 (95% CI: 1.13-1.67, P = .000, n = 8) in a multivariable-adjusted model. A significant association was observed in subgroup younger than 70 years (OR = 1.40, 95% CI: 1.09-1.79, P = .000, n = 6), but not in subgroup older than 70 years (OR = 1.28, 95% CI: 0.89-1.83, P = .186, n = 2). For subclinical hyperthyroidism, the summary OR was 1.16 (95%CI: 0.97-1.39, P = .115, n = 5) and subgroup analyses by age and study design did not alter the results significantly.Conclusions: Our findings demonstrated that subclinical hypothyroidism was significantly associated with a higher risk of CKD independent of some conventional risk factors among community population and age might have modifying effects on the association.

Preparation and characterization of micro-cell membrane chromatographic column with silica-based porous layer open tubular capillary as cellular membrane carrier.

Cell membrane chromatography (CMC) is a powerful tool to study membrane protein interactions and to screen active compounds extracted from natural products. Unfortunately, a large amount of cells are typically required for column preparation in order to carry out analyses in an efficient manner. Micro-CMC (mCMC) has recently been developed by using a silica capillary as a membrane carrier. However, a reduced retention of analytes is generally associated with mCMC mostly due to a low ligand (cellular membrane) capacity. To solve this common problem, in this work a silica-based porous layer open tubular (PLOT) capillary was fabricated and, to the best of our knowledge, for the first time applied to mCMC. The mCMC column was prepared by physical adsorption of rabbit red blood cell (rRBC) membranes onto the inner surface of the PLOT capillary. The effects of the PLOT capillaries fabricated by different feed compositions, on the immobilization amount of cellular membranes (represented by the fluorescence intensity of the capillary immobilized with fluorescein isothiocyanate isomer-labeled cellular membranes) and on the dynamic binding capacity (DBC) of verapamil (VP, a widely used calcium antagonist which specific interacts with L-type calcium channel proteins located on cellular membrane of rRBC) have been systematically investigated. The fluorescence intensity of the mCMC column when combined with the PLOT capillary was found to be more than five times higher than the intensity using a bare capillary. This intriguing result indicates that the PLOT capillary exhibits a higher cellular membrane capacity. The DBC of VP in the PLOT column was found to be more than nine times higher than that in the bare capillary. An rRBC/CMC column was also prepared for comparative studies. As a result, mCMC provides similar chromatographic retention factors and stability with common CMC; however, the cellular membrane consumption for mCMC was found to be more than 460 times lower than that for CMC. Graphical Abstract Comparision of mCMC chromatograms and SEM images between bare capillary and PLOT capillary.

Progress in the research of immunotherapy­related hyperprogression (Review).

Immunotherapy has become an effective method for the treatment of a variety of malignant tumors. However, with the development of immunotherapy, the phenomenon of hyperprogression in patients with cancer has gradually attracted attention. Hyperprogression refers to a condition in which the progression of a disease during treatment of a patient with cancer is suddenly accelerated. To date, no reliable marker has been found to predict accelerated tumor growth during immune checkpoint inhibitor (ICI) treatment. The aim the present study was to summarize the definition of hyperprogression and the difference between hyperprogression and pseudocytosis, and investigate the potential mechanisms of hyperprogression including clinical characteristics, potential molecular markers and the immune microenvironment. The effect of macrophage-related different types and factors on tumors in the immune microenvironment was analyzed, and the findings may be used to determine the future directions of research in hyperprogression.

Migration of microorganisms between nitrification-denitrification flocs, anammox biofilms and blank carriers during mainstream anammox start-up.

To solve the shortage of inoculum, the feasibility of establishing simultaneous partial nitrification, anammox, and denitrification (SNAD) reactor through inoculating nitrification-denitrification sludge, anammox biofilm and blank carriers was investigated. Advanced nitrogen removal efficiency of 91.2 ± 3.6 % was achieved. Bacteria related to nitrogen removal and fermentation were enriched in anammox biofilm, blank carriers and flocs, and the abundance of dominant anaerobic ammonia oxidizing bacteria (AnAOB), Candidatus Brocadia, reached 3.4 %, 0.5 % and 0.3 %, respectively. Candidatus Competibacter and Calorithrix became the dominant denitrifying bacteria (DNB) and fermentative bacteria (FB), respectively. The SNAD system was successfully established, and new mature biofilms formed in blank carriers, which could provide inoculum for other anammox processes. Partial nitrification, partial denitrification and aerobic_chemoheterotrophy were existed and facilitated AnAOB enrichment. Microbial correlation networks revealed the cooperation between DNB, FB and AnAOB that promoted nitrogen removal. Overall, the SNAD process was started up through inoculating more accessible inoculum.

A triple-spark guiding strategy to enhance the loser-out tournament-based fireworks algorithm.

Loser-out tournament-based fireworks algorithm (LoTFWA) is a new baseline of fireworks algorithm (FWA). However, its ability to search deeply in local areas and communicate among fireworks is not satisfying enough. Therefore, this paper proposes a new triple-spark guiding strategy for LoTFWA to deal with the mentioned problems. Among the three sparks generated for guiding, one is exactly the same as the original one in LoTFWA, the second one uses the centroid of good sparks to enhance the local exploitation, and the last one is based on Differential evolution (DE) mutation and used to enhance cooperation and exploration. Experimental results show that with low computational cost, the proposed guiding strategy attains significantly better results than LoTFWA and is competitive with state-of-the-art FWA variants. Furthermore, comprehensive experiments show that the proposed strategy has the potential to combine with other FWA variants to achieve better results.

An enhanced Runge Kutta boosted machine learning framework for medical diagnosis.

With the development and maturity of machine learning methods, medical diagnosis aided with machine learning methods has become a popular method to assist doctors in diagnosing and treating patients. However, machine learning methods are greatly affected by their hyperparameters, for instance, the kernel parameter in kernel extreme learning machine (KELM) and the learning rate in residual neural networks (ResNet). If the hyperparameters are appropriately set, the performance of the classifier can be significantly improved. To boost the performance of the machine learning methods, this paper proposes to improve the Runge Kutta optimizer (RUN) to adaptively adjust the hyperparameters of the machine learning methods for medical diagnosis purposes. Although RUN has a solid mathematical theoretical foundation, there are still some performance defects when dealing with complex optimization problems. To remedy these defects, this paper proposes a new enhanced RUN method with a grey wolf mechanism and an orthogonal learning mechanism called GORUN. The superior performance of the GORUN was validated against other well-established optimizers on IEEE CEC 2017 benchmark functions. Then, the proposed GORUN is employed to optimize the machine learning models, including the KELM and ResNet, to construct robust models for medical diagnosis. The performance of the proposed machine learning framework was validated on several medical data sets, and the experimental results have demonstrated its superiority.

Achieving advanced nitrogen removal and excess sludge treatment via single nitritation/anammox-fermentation combined system.

The feasibility of treating wastewater and excess sludge via simultaneous nitritation, anammox, denitrification and fermentation (SNADF) was investigated in three parallel sequencing batch reactors (SBRs). SBR2 and SBR3 received exogenous nitrification-denitrification sludge and thermal hydrolysis sludge, respectively. Nitrogen removal efficiencies of 92.8 ± 5.9%, 94.6 ± 4.1%, 93.4 ± 4.8% were achieved in SBR1, SBR2, and SBR3, respectively (influent ammonium: 56.0-74.0 mg N/L), with low observed sludge yield of 0.02-0.15, -0.06-0.11, -0.17-0.05 kg mixed liquor suspended solids (MLSS)/kg chemical oxygen demand (COD). Anammox bacterial abundances increased from 3.6 × 109 ± 2.8 × 108 to 8.1 × 109 ± 2.3 × 108, 1.5 × 1010 ± 1.1 × 108, and 1.4 × 1010 ± 2.9 × 108 copies/L in SBR1-SBR3, respectively. The abundances of Nitrosomonas, genes (amo, hao) for partial nitrification, and narGHI genes (nitrate â†’ nitrite) in dominant partial denitrifying bacteria (Candidatus Competibacter) were higher in SBR2 and SBR3 than that in SBR1. These results suggested that adding excess sludge promoted sludge reduction, nitrite production and anammox bacterial enrichment. The SNADF system could treat excess sludge, meanwhile, achieve advanced nitrogen removal.

A novel simultaneous partial nitrification, anammox, denitrification and fermentation process: Enhancing nitrogen removal and sludge reduction in a single reactor.

This study verified the feasibility of simultaneous partial nitrification, anammox, denitrification and fermentation process under intermittent aeration in a single reactor, and explored the impact of dissolved oxygen (DO) on the synergy between fermentation and nitrogen removal. An advanced nitrogen removal efficiency of 92.8 % and a low observed sludge yield of 0.0268-0.1474 kgMLSS/kgCOD were achieved. In-situ test showed that nitrate and ammonium decreased synchronously in the absence of organic matter, indicating the possibility of simultaneous partial denitrification, anammox and fermentation. Additionally, the abundance of functional genes for acetate production was 66,894 hits, while the key genes relevant to methanogenesis were only 348 hits, which suggested that fermentation might stop at the acid-producing stage and promote partial denitrification-anammox reaction, achieving simultaneous sludge reduction and advanced nitrogen removal performance. When DO increased from 0.1-0.3 to 0.4-0.6 mg/L, the nitrogen removal efficiency was increased (63.9 %→92.8 %) while sludge reduction was negatively affected.

Enhancing nitrite production rate made anammox bacteria have a competitive advantage over nitrite oxidizing bacteria in mainstream anammox system.

Nitrite oxidizing bacteria (NOB) is easy to accumulate in the mainstream anammox process, leading to the decrease of anammox bacterial abundance and deterioration of nitrogen removal. In this study, anammox bacteria was gradually enriched by increasing nitrite production rate under intermittent aeration despite high NOB abundance. With the DO increased from 0.4 to 0.6 mg/L, Nitrosomonas increased from 0.14% to 0.22%, providing more nitrite for anammox bacteria and promoting its enrichment (grew by 77.4%). Adding extra nitrite of 7.14 mg N/(L·h) during the aeration phase to reactor could further increase anammox bacterial abundance by 117.6%, which was higher than the control reactor (40.2%). In contrast, NOB abundance decreased from 1.4 × 1010 to 1.2 × 1010 copies/L. The results suggested that anammox bacteria had a competitive advantage for nitrite over NOB with increasing nitrite production rate. In addition, Thauera and Dechloromonas, which were responsible for reducing nitrate to nitrite, provided additional substrates for anammox bacteria. Overall, this research provides a new idea for mainstream anammox applications. PRACTITIONER POINTS: Inhibiting NOB might be no longer necessary and difficult for mainstream anammox. Anammox bacteria competed for more nitrite with NOB when nitrite production rate increased. Increasing DO from 0.4 to 0.6 mg/L facilitated anammox bacterial growth and nitrogen removal.

A mid-infrared high-performance spectropolarimetry filter based on dual-mode independent modulation.

Spectropolarimetry detection provides multi-dimensional accurate information with broad applications from biomedicine to remote sensing. Existing methods for simultaneously obtaining spectra and polarizations are either large and complex systems or miniaturized devices with too low spectral resolution or poor polarization selectivity, which inherently generate cross-talk of substantial information. Here, we propose a compact and single-chip integrated high-performance mid-infrared spectropolarimetry filter (SPF), whose narrowband spectral and polarization characteristics can be independently modulated by different polarization modes. A SPF is designed with a polarization extinction ratio (ER) over 106, spectral resolution (SR, λ/Δλ) up to 822 and a transmission efficiency of 90% in the mid-infrared band. The experimental ER and SR are over 3 × 104 and up to 387 respectively with a transmission efficiency of 60%. These results agree well with the theoretical results and can accurately obtain spectral and polarization information simultaneously. This device has been used in tumor diagnostics to well distinguish striated muscle and rhabdomyosarcoma tissue for demonstration. It can be easily extended to different wavelength ranges and provides a new and powerful approach for multi-dimensional optical information acquisition, target detection and accurate identification.

An adaptive differential evolution algorithm with elite gaussian mutation and bare-bones strategy.

Both differential evolution algorithm (DE) and Bare-bones algorithm (BB) are simple and efficient, but their performance in dealing with complex multimodal problems still has room for improvement. DE algorithm has great advantages in global search and BB algorithm has great advantages in local search. Therefore, how to combine these two algorithms' advantages remains open for further research. An adaptive differential evolution algorithm based on elite Gaussian mutation strategy and bare-bones operations (EGBDE) is proposed in this paper. Some elite individuals are selected and then the mean and the variance of the bare-bones operation are adjusted with the information from the selected elite individuals. This new mutation strategy enhances the global search ability and search accuracy of differential evolution with parameters free. It also helps algorithm get a better search direction and effectively balance the exploration and exploitation. An adaptive adjustment factor is adopted to dynamically balance between differential mutation strategy and the elite Gaussian mutation. Twenty test functions are chosen to verify the performance of EGBDE algorithm. The results show that EGBDE has excellent performance when comparing with other competitors.

Start-up of mainstream anammox process through inoculating nitrification sludge and anammox biofilm: Shift in nitrogen transformation and microorganisms.

The feasibility of starting up mainstream single-stage partial nitrification-anammox (SPNA) system by inoculating nitrification sludge and anammox biofilm was investigated. The SPNA system treating low-strength synthetic wastewater was rapidly started up with TN removal efficiency of 88.5 ± 1.8% and effluent nitrate concentration of 7.2 ± 1.2 mg/L. Both the abundance and maximum activity of nitrite oxidizing bacteria (NOB) in flocs decreased obviously. Interestingly, the abundance of anaerobic ammonium oxidizing bacteria (AnAOB) in flocs increased from 0.213% to 0.346% despite the sludge retention time (SRT) of flocs decreased to 60 days, the AnAOB in biofilm was 0.434%. That meant AnAOB gradually enriched in flocs and accounted for a fairly high proportion. The inhibition of NOB, partial denitrification and increased aerobic_chemoheterotrophy function in flocs might be the main reasons for AnAOB enrichment. The possibility of simultaneous fermentation, partial denitrification and anammox reaction was predicted in biofilm, further improving the stability of the system.

MOEA/D With Linear Programming for Double Row Layout Problem With Center-Islands.

Facility layout problems (FLPs) in hospitals are typically to arrange facilities or rooms along both sides of a corridor to minimize some objectives. In a hospital, very often there are center-islands to decrease the flow cost among facilities or rooms. However, these islands have not been considered before. In this article, we propose an FLP with center-islands that involves two parallel rows and center-islands. A mixed-integer program formulation is established for modeling it. A methodology for combining a multiobjective evolutionary algorithm based on decomposition (MOEA/D) and linear program is proposed to solve this problem. MOEA/D optimizes the sequence of facilities on two rows and center-islands while the linear program is embedded into MOEA/D to optimize the exact locations of center-islands. A tabu search with a local search is also integrated into MOEA/D to enhance its search capability. Experiments show that our proposed methodology can effectively solve the problem.

[Study on C21 steroidal glycosides of Cynanchum atratum by LC-MS].

High performance liquid chromatography coupled with on-line electrospray tandem mass spectrometry (HPLC/ESI-MS/MS) was used to identify C21 steroidal glycosides in the roots of Cynanchum atratum. The structures of C21 steroidal glycosides were deduced from mass fragments features in positive and negative mode. The constituents of C. atratum were separated and detected. 7 compounds were identified by comparing their ESI-MS/MS data with the reference compounds and 2 compounds were inferred solely by the ESI-MS/MS data. The method is sensitive, and provides good separation and rapid qualitative characterization of C21 steroidal glycosides in the roots of C. atratum.