Low complexity equalization in coherent optical communication based on Fermat number transform.

In order to reduce the power consumption of digital signal processing (DSP) in a coherent optical communication system, a low complexity equalization scheme in DSP flow of a 400 Gb/s DP-16QAM system has been proposed. This scheme is based on Fermat number transform (FNT), which sequentially performs static equalization (SE) and dynamic equalization (DE) in the transform domain. For different distances, the proposed scheme finds the optimal solution under the condition that transform length and data bit width are mutually restricted under different transmission distances while achieving low complexity and optimal performance. The experimental results show that the adopted transform-domain equalization (TrDE) scheme has much lower computational complexity than the traditional frequency-domain equalization (FDE) and time-domain equalization (TDE) nearly without any performance loss. In the 80, 160, and 240 km scenarios, the number of multiplier is reduced by more than 72%, and the advantage becomes more obvious as the transmission capacity increases.

Enabling endogenous distributed acoustic sensing in a digital subcarrier coherent transmission system.

To monitor the health of the fiber network and its ambient environment in densely populated access/metro network areas, in this Letter, an endogenous distributed acoustic sensing (DAS) has been proposed and achieved in a coherent digital subcarrier multiplexing (DSCM) system. Rather than specially allocating a sensing probe in general integrated communication and sensing schemes, the fractional Fourier transformed (FrFT) training sequence (TS) designated for time/frequency synchronization in DSCM coherent communications has been repurposed for sensing. While achieving excellent synchronization performance of communication, the FrFT-based TS can also be concurrently utilized to perform distributed vibration sensing. Experimental results demonstrate that the FrFT-based timing/frequency synchronization sequence is repurposed to achieve a DAS sensitivity of 70 p ε/Hz at a spatial resolution of 5 m, along with 100-Gb/s 16 quadrature amplitude modulation (QAM) DSCM transmission, without a loss of spectral efficiency.

Hydrogen Bond and Dipole-Dipole Interaction Enabling Ultrastable, Quick Responding, and Self-Healing Proton Exchange Membranes for Fuel Cells.

Proton exchange membranes (PEMs) are subject to mechanical degradation, such as microcracks and pinhole formation, under real-world fuel cell operating conditions, which leads to great issues in terms of device death and safety concerns. Therefore, PEMs with self-healing features are imperative but have rarely been used for proton exchange membrane fuel cells (PEMFCs). Here, a dimensionally stable and self-healing PEM is developed by tuning the hydrogen bond and dipole-dipole interactions between the mature perfluorinated sulfonic acid (PFSA) and a self-healing copolymer, which is specifically synthesized with hexafluorobutyl acrylate (HFBA) and acrylic acid (AA). This hexafluorobutyl acrylate-acrylic acid copolymer (HFBA-co-AA) is suggested as the key to improving the self-healing efficiency of the blended PFSA/HFBA-co-AA membrane. This PFSA/HFBA-co-AA membrane can recover 43.6% of the original tensile strength within only 20 min at 80 °C. This study may pave an avenue toward the development of reliable and durable PEM for fuel cells.

Exploring Alashan Ground Squirrel (Spermophilus alashanicus) Diversity: Metagenomic and Transcriptomic Datasets from the Helan Mountains.

This study investigates the adaptive strategies of the Alashan Ground Squirrel (Spermophilus alashanicus) in response to habitat changes, as rodents are sensitive indicators of ecosystem changes. Despite its ecological importance, the genome and microbiome of this species have not been thoroughly studied. This research fills this gap by presenting the first comprehensive metagenomic and transcriptomic datasets of the species. Transcriptomic data was collected from five tissue types, including heart, liver, cecum, muscle, and blood, resulting in the assembly of 72,156 unigenes. Metagenomic sequencing identified predominant bacterial groups such as Firmicutes, Bacteroidetes, Verrucomicrobia, Urovircota, and Proteobacteria. Our workflow involved RNA and DNA extraction, library preparation, assembly, and annotation, yielding valuable insights into gene discovery, microbial composition, and further genome and microbial function studies. In conclusion, our findings have significant implications for understanding the adaptive mechanisms of this species in response to environmental changes.

Unraveling a volcanic relationship of Co/N/C@PtxCo catalysts toward oxygen electro-reduction.

The cathodic oxygen reduction reaction (ORR) has been continuously attracting worldwide interest due to the increasing popularity of proton exchange membrane (PEM) fuel cells. So far, various Pt-group metal (PGM) or PGM-free catalysts have been developed to facilitate the ORR. However, there is still a gap to achieve the expected goals as proposed by the U.S. Department of Energy (DoE). Recently, PGM-free@PGM hybrid catalysts, such as the M/N/C@PtM catalyst, have achieved the milestones of oxygen reduction, as reviewed in our recent work. It is, nevertheless, still challenging to unravel the underlying structure-property relationships. Here, by applying different Pt/Co ratios, a series of Co/N/C@PtxCo catalysts are synthesized. Interestingly, the ORR activity and stability are not linear with the Pt content, but show a volcano-like curve with increased Pt usage. This relationship has been deeply unraveled to be closely related to the contents of pyrrolic N, pyridinic N, and graphitized carbon in catalysts. This work provides guidelines to rationally design the coupled PGM-free@PGM catalysts toward the ORR by appropriate surface engineering.

PDM-SHD NFDM transmission with envelope-detection feedback polarization tracking and optical injection locking.

Nonlinear frequency division multiplexing (NFDM) systems, especially the eigenvalue communications have the potential to overcome the nonlinear Shannon capacity limit. However, the baud rate of eigenvalue communications is typically restricted to a few GBaud, making it challenging to mitigate laser frequency impairments such as the phase noise and frequency offset (FO) using digital signal processing (DSP) algorithms in intradyne detections (IDs). Therefore, we introduce the polarization division multiplexing-self-homodyne detection (PDM-SHD) into the NFDM link, which could overcome the impact of phase noise and FO by transmitting a pilot carrier originating from the transmitter laser to the receiver through the orthogonal polarization state of signal. To separate the signal from the carrier at the receiver, a carrier to signal power ratio (CSPR) unrestricted adaptive polarization controlling strategy is proposed and implemented by exploiting the optical intensity fluctuation of the light in a particular polarization rather than its direct optical power as the feedback. Optical injection locking (OIL) is used subsequently to amplify optical power of pilot carrier and mitigate the impact of signal-signal beat interference (SSBI). Additionally, the effects of cross-polarization modulation (XPolM) and modulation instability (MI) in long haul transmission are explored and inhibited. The results show that the tolerable FO range is about 3.5 GHz, which is 17 times larger than the ID one. When 16-amplitude phase shift keying (APSK) or 64-APSK constellations are used, identical Q-factor performance can be obtained by using distributed feedback (DFB, ∼10 MHz) laser, external cavity laser (ECL, ∼100kHz), or fiber laser (FL, ∼100 Hz), respectively, which demonstrates that our proposed PDM-SHD eigenvalue communication structure is insensitive to the laser linewidth. Under the impact of cycle slip, the Q-factor difference of 16-APSK signal between the ECL-ID system and ECL-SHD system can be up to 8.73 dB after 1500 km transmission.

Enabling cost-effective high-performance vibration sensing in digital subcarrier multiplexing systems.

Enabling communication networks with sensing functionality has attracted significant interest lately. The digital subcarrier multiplexing (DSCM) technology is widely promoted in short-reach scenarios for its inherent flexibility of fine-tuning the spectrum. Its compatibility with large-scale as-deployed coherent architectures makes it particularly suited for cost-sensitive integrated sensing and communication applications. In this paper, we propose a scheme of spectrally integrating the digital linear frequency modulated sensing signal into DSCM signals to achieve simultaneous sensing and communication through shared transmitter. Consequently, this cost-effective scheme has been demonstrated to achieve 100-Gb/s dual-polarization quadrature phase-shift keying (DP-QPSK) and 200-Gb/s dual-polarization 16-ary quadrature amplitude modulation (DP-16QAM) transmission with a distributed acoustic sensing sensitivity of 69 pε/Hz and 88 pε/Hz respectively, at a spatial resolution of 4 m.

High-performance aqueous zinc ion hybrid capacitors obtained by Na2SO4 additive and dense pore structure.

In this study, the electrochemical performance of zinc ion hybrid capacitors (ZICs) was improved by employing carbon-based materials and electrolyte together. First, we prepared pitch-based porous carbon HC-800 as the electrode material, which possessed a large specific surface area (3607 m2 g-1) and a dense pore structure. This provided abundant adsorption sites for zinc ions, and thus stored more charges. Subsequently, 0.5 M Na2SO4 was added to 1 M Zn(CF3SO3)2 electrolyte via the cationic additive strategy, and the adsorption energy of sodium and zinc ions on the zinc electrode was calculated. The results showed that sodium ions would preferentially be adsorbed on the surface of the zinc electrode, which would inhibit the growth of zinc dendrites, and thus prolong the service life of the zinc electrode. Finally, the presence of solvated zinc ions in the narrowly distributed pores of HC-800 was studied, and the results showed that Zn(H2O)62+ underwent a desolvation process, resulting in the removal of two water molecules to form a tetrahedral structure of Zn(H2O)42+, which made the central surface of the zinc ions closer to the surface of HC-800, and thus the more capacitance achieved. Furthermore, the uniform distribution of Zn(H2O)42+ in the dense and neat pores of HC-800, improved the space charge density. Consequently, the assembled ZIC exhibited a high capacity (242.25 mA h g-1 at 0.5 A g-1) and ultra-long cycle stability (capacity retention at 87% after 110 000 charge/discharge cycles at a high current density of 50 A g-1 and a coulombic efficiency of 100%) and an energy density of 186.1 W h kg-1 and power density of 41 004 W kg-1.

Health benefits of saponins and its mechanisms: perspectives from absorption, metabolism, and interaction with gut.

Saponins, consisting of sapogenins as their aglycones and carbohydrate chains, are widely found in plants and some marine organisms. Due to the complexity of the structure of saponins, involving different types of sapogenins and sugar moieties, investigation of their absorption and metabolism is limited, which further hinders the explanation of their bioactivities. Large molecular weight and complex structures limit the direct absorption of saponins rendering their low bioavailability. As such, their major modes of action may be due to interaction with the gastrointestinal environment, such as enzymes and nutrients, and interaction with the gut microbiota. Many studies have reported the interaction between saponins and gut microbiota, that is, the effects of saponins on changing the composition of gut microbiota, and gut microbiota playing an indispensable role in the biotransformation of saponins into sapogenins. However, the metabolic routes of saponins by gut microbiota and their mutual interactions are still sparse. Thus, this review summarizes the chemistry, absorption, and metabolic pathways of saponins, as well as their interactions with gut microbiota and impacts on gut health, to better understand how saponins exert their health-promoting functions.

Ultrasonic hemodynamic changes of superficial temporal artery graft in different angiogenesis outcomes of Moyamoya disease patients treated with combined revascularization surgery.

Objective: Combined bypass is commonly used in adult Moyamoya disease (MMD) for revascularization purposes. The blood flow from the external carotid artery system supplied by the superficial temporal artery (STA), middle meningeal artery (MMA), and deep temporal artery (DTA) can restore the impaired hemodynamics of the ischemic brain. In this study we attempted to evaluate the hemodynamic changes of the STA graft and predict the angiogenesis outcomes in MMD patients after combined bypass surgery by using quantitative ultrasonography. Methods: We retrospectively studied Moyamoya patients who were treated by combined bypass between September 2017 and June 2021 in our hospital. We quantitatively measured the STA with ultrasound and recorded the blood flow, diameter, pulsatility index (PI) and resistance index (RI) to assess graft development preoperatively and at 1 day, 7 days, 3 months, and 6 months after surgery. All patients received both pre- and post- operative angiography evaluation. Patients were divided into either well- or poorly-angiogenesis groups according to the transdural collateral formation status on angiography at 6 months after surgery (W group or P group). Patients with matshushima grade A or B were divided into W group. Patients with matshushima grade C were divided into P group, indicating a poor angiogenesis development. Results: A total of 52 patients with 54 operated hemispheres were enrolled, including 25 men and 27 women with an average age of 39 ± 14.3 years. Compared to preoperative values, the average blood flow of an STA graft at day 1 postoperation increased from 16.06 ± 12.47 to 117.47± 73.77 (mL/min), diameter increased from 1.14 ± 0.33 to 1.81 ± 0.30 (mm), PI dropped from 1.77 ± 0.42 to 0.76 ± 0.37, and RI dropped from 1.77 ± 0.42 to 0.50 ± 0.12. According to the Matsushima grade at 6 months after surgery, 30 hemispheres qualified as W group and 24 hemispheres as P group. Statistically significant differences were found between the two groups in diameter (p = 0.010) as well as flow (p = 0.017) at 3 months post-surgery. Flow also remained significantly different at 6 months after surgery (p = 0.014). Based on GEE logistic regression evaluation, the patients with higher levels of flow post-operation were more likely to have poorly-compensated collateral. ROC analysis showed that increased flow of ≥69.5 ml/min (p = 0.003; AUC = 0.74) or a 604% (p = 0.012; AUC = 0.70) increase at 3 months post-surgery compared with the pre-operative value is the cut-off point which had the highest Youden's index for predicting P group. Furthermore, a diameter at 3 months post-surgery that is ≥0.75 mm (p = 0.008; AUC = 0.71) or 52% (p =0.021; AUC = 0.68) wider than pre-operation also indicates a high risk of poor indirect collateral formation. Conclusions: The hemodynamic of the STA graft changed significantly after combined bypass surgery. An increased flow of more than 69.5 ml/min at 3 months was a good predictive factor for poor neoangiogenesis in MMD patients treated with combined bypass surgery.

Modified Distributed Bragg Reflectors for Color Stability in InGaN Red Micro-LEDs.

The monolithic integration of InGaN-based micro-LEDs is being of interest toward developing full-color micro-displays. However, the color stability in InGaN red micro-LED is an issue that needs to be addressed. In this study, the modified distributed Bragg reflectors (DBRs) were designed to reduce the transmission of undesired spectra. The calculated optical properties of the InGaN red micro-LEDs with conventional and modified DBRs have been analyzed, respectively. The CIE 1931 color space and the encoded 8-bit RGB values are exhibited for the quantitative assessment of color stability. The results suggest the modified DBRs can effectively reduce the color shift, paving the way for developing full-color InGaN-based micro-LED displays.

Blind SOP recovery of eigenvalue communication system based on a nonlinear Fourier transform.

Owing to the random birefringence of optical fibers, the recovery of the state of polarization (SOP) is urgently needed, especially in the nonlinear spectrum division multiplexing transmissions. Based on the variance of the polarization power ratio among symbols as the cost function, we propose a novel algorithm for the blind SOP recovery of eigenvalue communications. In the single eigenvalue transmissions with phase-shift keying or 16-ary amplitude and phase-shift keying constellations, at least 25.3 dB polarization extinction ratio can be achieved by using a block length of 30, even under 7 dB OSNR condition. It also shows that the proposed algorithm can be employed in multi-eigenvalue NFDM transmissions and full-spectrum modulated NFDM system. In the experiment, our proposed algorithm performs the same as the training symbol based method in back-to-back and less than 3000 km fiber link conditions; a maximum performance gain of 1.6 dB was obtained in ultra-long-haul condition (4300 km). It also shows that the impact of the polarization mode dispersion of a single-mode fiber on the algorithm is negligible.

High-security constellation shaped self-homodyne coherent system with 4-D joint encryption.

In recent years, the self-homodyne coherent (SHC) system and the constellation shaping (CS) technique have drawn considerable attention due to their abilities to further improve the transmission capacity for various scenarios. From the security point of view, the CS technique and the SHC infrastructure also provide new dimensions for encryption. We propose a high-security and reliable SHC system based on the CS technique and the digital chaos. With a four-dimensional hyperchaotic system, chaotic sequences are generated and used for the exclusive or operation, chaotic constant composition distribution matching, phase disturbance, and optical-layer time-delay disturbance. Moreover, 64-ary circular quadrature amplitude modulation (64CQAM) format is adopted for transmission due to its advantages of sensitivity to phase noise, immunity to conventional digital signal processing, and ability of time-mismatch masking, which is verified by simulation in a SHC system. Last, we conduct an experimental verification in a 20GBaud probabilistically shaped 64CQAM SHC system. Consequently, with a large-linewidth laser source, optical-layer security can be protected by time mismatches of tens of picoseconds. And the digital-layer security is protected by an enormous key space of 10127. The proposed scheme can provide reliable real-time encryption for the optical fiber transmission, serving as a potential candidate for the future high-capacity inter/intra-datacenter security interconnect.

The complete mitochondrial genome of the Brambling Fringilla montifringilla (Passeriformes: Fringillidae) from Maor Mountain, China.

The Brambling (Fringilla montifringilla) (Linnaeus 1758) is a member of the Passeriformes family of birds and primarily feeds on grass seeds and grains. Muscle tissue was collected from birds sampled from Moar Mountain, China, and the complete mitochondrial genome was sequenced. Its mitochondrial genome consists of 13 protein-coding genes (PCGs), 2 rRNA genes (12S rRNA and 16S rRNA), 22 tRNA genes, and 1 control region (CR). The genome comprises 30.30% A, 23.32% T, 14.31% G, and 32.07% C bases. Phylogenetically, F. montifringilla is closely related to the Fringilla coelebs, Fringilla teydea teydea and Fringilla polatzeki.

Adaptive bias control of optical IQ modulator with low LFM dither and strong fluctuation resistance.

An innovative approach has been proposed for adaptive bias control in optical IQ modulators. In contrast to traditional approaches that utilize sine dither, this method employs a linear frequency modulated (LFM) signal as the dither, associated with the fractional Fourier Transform (FrFT) to extract the bias point drift. The LFM signal, after undergoing FrFT, transforms into a compressed signal (CS) with energy concentration in the fractional domain. Utilizing this signal for bias point monitoring, the proposed method demonstrates robust bias control even in the presence of substantial interferences, as substantiated by comprehensive simulations and experimental investigations. Remarkably, in a 20-Gbaud 16QAM signal transmission, the proposed approach achieves stable control of the bias point for over 4 hours, even in the presence of voltage fluctuations, while effectively reducing the dither amplitude by half. Furthermore, it maintains a low bit error rate (BER) below 10-5 even under intentional external interference.

Characterization of the complete mitochondrial genome of the Lesser Spotted Woodpecker (Dryobates minor) and its phylogenetic position.

In this study, we sequenced and assembled the complete mitochondrial genome of Dryobates minor by next-generation sequencing. The mitochondrial genome of Dryobates minor is 16,847 bp in length and consists of 13 protein-coding genes (PCGS), two ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes and 1 control region (CR). The CG content of the mitochondrial genome is 47.46%. Only one overlap among the 13 protein-coding genes was found: ND4L/ND4. Phylogenetic analysis based on a combined mitochondrial gene dataset indicated that the mitochondrial genome of Dryobates minor exhibited a close relationship with that of Picoides pubescens.

The complete mitochondrial genome of the Pale-legged Leaf-Warbler Phylloscopus tenellipes (Aves: Phylloscopidae) from Maor Mountain, China.

The Pale-legged Leaf-Warbler (Phylloscopus tenellipes) (Swinhoe, 1860) is an olive-brown warbler that is extensively dispersed in Asia. We sequenced the whole mitochondrial genome of a Pale-legged Leaf-Warbler collected on Maor Mountain, Heilongjiang Province, China. The mitochondrial genome is 16,972 bp and contains 13 protein-coding genes, two rRNA genes, 22 tRNA genes, and one control region (CR). The CR is 1098 bp. The nucleotide sequence is composed of 29.11% A, 22.98% T, 14.64% G, and 33.27% C. Phylogenetic research revealed that P. tenellipes is closely related to Phylloscopus borealoides.

Modeling and mitigation of polarization crosstalk-induced nonlinearity for the polarization-multiplexed carrier self-homodyne system.

In this Letter, we analytically model the impact of polarization crosstalk in the polarization-multiplexed carrier self-homodyne (PMC-SH) system with adaptive polarization control technology. When the optical paths of the signal and local oscillator (LO) are matched well, it is found that the polarization crosstalk results in a nonlinear shift on the constellation. Thus, we further propose a compensation scheme based on a low-complexity polynomial nonlinear equalizer (PNLE). Both simulation and experimental results validate our theoretical analysis. Moreover, the proposed PNLE-based compensation scheme achieves up to 1.23 dB tolerance improvement with respect to polarization crosstalk for 20 Gbaud 64QAM in the experiment.

Characterization of Saponins from Differently Colored Quinoa Cultivars and Their In Vitro Gastrointestinal Digestion and Fermentation Properties.

Quinoa contains rich saponins, which are removed during processing and cause ecological waste. We extracted saponins from quinoa (SEQ) in black, white, and red cultivars and compared their composition by spectrophotometric assay and high-performance liquid chromatography analysis combined with acid hydrolysis. The digestion and fermentation properties of SEQ were investigated using an in vitro model. Our results showed that acid hydrolysis released sapogenins, mainly phytolaccagenin (PA), hederagenin (HD), and oleanolic acid from SEQ. Varying from SEQ in red, SEQ in black and white had a similar composition and content of sapogenins. Gastrointestinal digestion did not release sapogenins from SEQ but reduced the antioxidant activity of SEQ. Gut microbiota from human feces released PA and HD from SEQ. Reciprocally, SEQ in black significantly increased the growth of Lactobacillus spp. and Bifidobacterium spp., while reducing the growth of Shigella spp. The present study provides guidance for further investigation about the bioactivities of saponins from quinoa.

Predictability of the Oxford classification of IgA nephropathy in Henoch-Schonlein purpura nephritis.

BACKGROUND: Whether the Oxford classification of immunoglobulin A nephropathy can be utilized to predict the adverse renal outcome of Henoch-Schonlein purpura nephritis (HSPN) has been long-debated. We, therefore, performed a meta-analysis to evaluate the prognostic value of Oxford classification lesions in HSPN. METHODS: We systematically searched Medline, EMBASE, Web of Science, and the Cochrane Library for articles published from January 1970 to August 2020. Cohort and case-control studies investigating the correlation between the Oxford classification and renal outcome were included, the quality of which was assessed by the Newcastle-Ottawa scale criteria. The pooled odds ratios (ORs) with their 95% confidence intervals (CIs) were calculated with a random-effects model or a fixed-effects model depending on the heterogeneity. RESULTS: A total of 485 papers were reviewed and eventually 9 comparisons were included, providing data of 1688 patients with HSPN. ORs for adverse renal events were 2.83 (95% CI 1.84-4.35; P < 0.001), 1.96 (95% CI 1.28-2.98; P < 0.05), and 5.45 (95% CI, 3.15-9.45; P < 0.001) for patients with lesions of endocapillary hypercellularity (E), segmental sclerosis (S), and tubular atrophy /interstitial fibrosis (T), respectively, without significant heterogeneity (E: I2 = 0.0%; P = 0.498; S: I2 = 22.4%; P = 0.258; T: I2 = 33.6%; P = 0.171). Subgroup analysis adjusted for age also supported the results that E, S, and T lesions could serve as poor predictors (P < 0.05). Additionally, crescents (C) were strongly associated with renal outcome (OR 2.22; 95% CI 1.62-3.04; P < 0.001), with moderate heterogeneity (I2 = 49.3%; P = 0.066). However, it should be noted that it is not the presence but the proportions of crescent lesions that were related to the high risk of progression to adverse renal events, because the predictability of lower rates of crescent (C1, with crescents > 0 and ≤ 25%) was uncertain (OR 2.21; 95% CI 0.75-6.51; P > 0.05). Although the pooled OR revealed that lesions of mesangial hypercellularity (M) were correlated with poor renal prognosis (OR 2.41; 95% CI 1.07-5.43; P < 0.05), subgroup analysis separating children from adults indicated that there seemed to be no significant difference. CONCLUSIONS: Oxford classification, especially for E, S, T, and C, might be recommended for patients with HSPN, regardless of children and adults.