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Microbial communities play an important role in water quality regulation and biogeochemical cycles in lakes, and their community structure and function are affected by environmental factors. Therein, antibiotics affect the abundance, diversity, composition, and function of microbial communities. In this study, Baiyangdian Lake was selected as the study area. Sediment samples of 16 sites were collected in August 2018 and April 2019, respectively. Ultra-high performance liquid chromatography-mass spectrometry ï¼HPLC-MS/MSï¼ was used to determine the content of typical antibiotics-quinolones ï¼QNsï¼ in sediment. Through high-throughput sequencing technology, the structure and function of microbial communities was analyzed in the sediments to explore the spatiotemporal variation. Thereinto, redundancy analysis ï¼RDAï¼ was used to identify the key influencing factors of spatiotemporal variation of microbial communities. The results showed thatï¼ â From August to April, the average ωï¼QNsï¼ showed an increasing trend, and its mean value changed from 3.91 ng·g-1 to 6.34 ng·g-1, with significant seasonal differences in oxolinic acid ï¼OXOï¼ and total QNs content ï¼P < 0.05ï¼. â¡ In terms of temporal variation, the dominant bacteria were Proteobacteria and Chloroflexi. The relative abundance of Proteobacteria showed a decreasing trend, whereas Chloroflexi showed an increasing trendï¼ at the genus level, the dominant bacteria genera in August were norank_ f__Anaerolineaceae and Thiobacilus, and the dominant bacteria genera in April were Acinetobacter and norank_ f_Anaerolineaceae, and the dominant bacteria genera had significant seasonal differences ï¼P < 0.05ï¼. ⢠In terms of temporal variation, the index of Simpson, Chao, Ace, and OTU number all showed an increasing trend, and the seasonal differences were significant ï¼P < 0.05ï¼. ⣠In terms of spatial variation, there were no significant spatial differences among functional genes of COG. In terms of temporal variation, there were significant seasonal differences in functional genes of energy production and conversion, carbohydrate transport and metabolism, transcription, cell wall/membrane/envelope biogenesis, and signal transduction mechanisms ï¼P < 0.01 and P < 0.05ï¼. ⤠Microbial community structure and functional genes were significantly correlated with QNs ï¼P < 0.01 and P < 0.05ï¼, and QNs were the main influencing factors. Therefore, QNs were the main factor affecting the changes in microbial community structure and functional genes in sediments of Baiyangdian Lake. Thus, comprehensive control of antibiotic pollution in sediments should be further strengthened.
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Antibacterianos , Sedimentos Geológicos , Lagos , Microbiota , Contaminantes Químicos del Agua , Lagos/microbiología , Sedimentos Geológicos/microbiología , Microbiota/genética , China , Contaminantes Químicos del Agua/análisis , Monitoreo del Ambiente , Quinolonas/análisis , Bacterias/clasificación , Bacterias/genéticaRESUMEN
Primary central nervous system vasculitis (PACNS) is a vasculitic disorder affecting small to medium-sized blood vessels primarily in the central nervous system,involving the brain,spinal cord,and meninges.Tumor-like PNCAS,a rare subtype of PACNS,is often misdiagnosed as intracranial malignancy,and that with spinal cord involvement is even more uncommon.The lack of specific clinical symptoms and imaging manifestations poses a challenge to the diagnosis of PACNS.This report presents a case of tumor-like PACNS with spinal cord involvement based on the pathological evidence,aiming to enrich the knowledge about this condition.
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Vasculitis del Sistema Nervioso Central , Humanos , Vasculitis del Sistema Nervioso Central/diagnóstico , Vasculitis del Sistema Nervioso Central/diagnóstico por imagen , Femenino , Masculino , Médula Espinal/diagnóstico por imagen , Médula Espinal/patología , Médula Espinal/irrigación sanguínea , Persona de Mediana EdadRESUMEN
Some patients with neuromyelitis optica spectrum disorder (NMOSD) experience relapse after rituximab (RTX) treatment. In this retrospective study, we analyzed the recurrence-related clinical features, laboratory investigation results, and dosing protocol of 30 female patients with relapsing NMOSD with immunoglobulin G autoantibodies against aquaporin-4 and relapses during repeated 0.5 g RTX infusions as maintenance treatment. The median follow-up period was 6.62 years. Thirty-five episodes were observed, with myelitis being the most frequent. The median expanded disability status scale change score was 0.50. The recurrence rate decreased by 44.23%/year with RTX infusion. Approximately 85.71% of the patients showed relapse without RTX infusion within 10 months. Overall, RTX may be effective for relapsing NMOSD cases.
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Rivers are important reservoirs of antibiotic resistance genes (ARGs). However, most current studies have focused on the temporal and spatial distribution, and data on the differences in the species and abundance of ARGs between urban and rural rivers is still lacking for certain areas. In view of this, two rural rivers and three urban rivers were selected in Shijiazhuang City. In both December 2020 and April 2021, sediments were collected at 15 sampling sites. Metagenomic sequencing technology was used to compare the differences in temporal-spatial variation for ARGs in sediments. The results showed that:â 162 and 79 ARGs were detected in urban (4 776 ±4 452) and rural rivers (1 043 ±632), respectively. The abundance and species of ARGs in urban rivers were higher than those in rural rivers. â¡ The relative abundances of sulfonamide (SAs,27 %), aminoglycoside (AGs,26 %), and multidrug (MDs,15 %) ARGs had the highest abundance in urban rivers, whereas the relative abundance of MDs ARGs was highest in rural rivers (65 %). On the whole, the complexity of ARGs in urban rivers was higher than that in rural rivers. ⢠There was a significant positive correlation between SAs, AGs, MDs, tetracycline, phenicol, macrolides-lincosamids-streptogramins (MLS), ß-lactams, and diaminopyrimidine ARGs in urban rivers (P < 0.01); however, there was a significant negative correlation between glycopeptide ARGs and all types of ARGs (P < 0.05 and P < 0.01). There was a significant positive correlation between MDs and SAs ARGs in rural rivers (P < 0.05), but there was a significant negative correlation between amino aminocoumarin, peptide, rifamycin, and fosfomycin ARGs (P < 0.05 and P < 0.01). ⣠For the temporal variation in urban rivers, 162 ARGs (4 776 ±4 452) and 148 ARGs (5 673 ±5 626) were detected in December and April, respectively. For the temporal variation in rural rivers, 79 species (1 043 ±632) and 46 species (467 ±183) were detected in December and April, respectively. ⤠RDA analysis results showed that the spatial-temporal distributions of ARGs in urban and rural rivers were different. Correlation analysis showed that the ARGs in urban rivers were significantly correlated with the number of industrial enterprises, whereas the ARGs in rural rivers were significantly correlated with the output value of animal husbandry. In general, this study identified the main influencing factors for ARGs in different rivers and provided data support for ARGs risk management in different rivers.
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Ciudades , Farmacorresistencia Microbiana , Sedimentos Geológicos , Ríos , Sedimentos Geológicos/microbiología , China , Farmacorresistencia Microbiana/genética , Monitoreo del Ambiente , Genes Bacterianos , Análisis Espacio-Temporal , Antibacterianos/análisisRESUMEN
Guavinoside B (GUB) is a characteristic constituent from guava with strong antioxidant activity; however, its low water solubility limits its utilization. Herein, we investigated the interaction between GUB and zein, a prolamin with self-assembling property, using multiple spectroscopic methods and fabricated GUB-zein-NaCas nanoparticles (GUB-Z-N NPs) via the antisolvent coprecipitation approach. GUB caused fluorescence quenching to zein via the static quenching mechanism. Fourier-transform infrared spectroscopy and computational analysis revealed that GUB bound to zein via van der Waals interaction, hydrogen bond, and hydrophobic forces. The GUB-Z-N NPs were in the nanometric size range (< 200 nm) and exhibited promising encapsulation efficiency and redispersibility after freeze-drying. These particles remained stable for up to 31 days at 4 °C and great resistance to salt and pH variation, and displayed superior antioxidant activity to native GUB. The current study highlights the potential of zein-based nanoparticles as delivery vehicles for GUB in the food industry.
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Caseínas , Nanopartículas , Psidium , Zeína , Zeína/química , Nanopartículas/química , Psidium/química , Caseínas/química , Extractos Vegetales/química , Portadores de Fármacos/química , Antioxidantes/química , Tamaño de la Partícula , Interacciones Hidrofóbicas e Hidrofílicas , Sistemas de Liberación de MedicamentosRESUMEN
To trace the origin of the gushing water in the riverine area of the Beijing section of The Middle Route of South-to-North Water Diversion Project, a dataset was established comprising water chemistry, three-dimensional fluorescence spectra, and stable isotopes for different water bodies. Results indicated significant differences in Electrical Conductivity (EC), Total Dissolved Solids (TDS), and Ca2+ concentration among the gushing water, river water, and the water from the Middle Route of South-to-North Water Diversion Project (MRSD). Analysis using parallel factor analysis (PARAFAC) and fluorescence index revealed that dissolved organic matter (DOM) in the MRSD mainly originated from endogenous sources, while the river water and gushing water showed influences from both endogenous and exogenous sources. Nitrate sources varied among the water bodies, with distinct contributions from domestic sewage and fertilizer sources. The evaporation lines of river water and gushing water exhibited similar intercepts and slopes, but their intercepts and slopes are much smaller than those of the MRSD, suggesting stronger kinetic evaporative fractionation. In conclusion, the gushing water in the riverine area of the MRSD was determined to originate from the river, providing a fast and efficient method for gushing water source identification.
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Ríos , Ríos/química , Beijing , Monitoreo del Ambiente , China , Contaminantes Químicos del Agua/análisisRESUMEN
In lake ecosystems, pelagic-benthic coupling strength (PBCS) is closely related to foodweb structure and pollutant transport. However, the trophic transfer of antibiotics in a benthic-pelagic coupling foodweb (BPCFW) and the manner in which PBCS influences the trophic magnification factor (TMFs) of antibiotics is still not well understood in the whole lake. Herein, the trophic transfer behavior of 12 quinolone antibiotics (QNs) in the BPCFW of Baiyangdian Lake were studied during the period of 2018-2019. It was revealed that 24 dominant species were contained in the BPCFW, and the trophic level was 0.42-2.94. Seven QNs were detected in organisms, the detection frequencies of ofloxacin (OFL), flumequine (FLU), norfloxacin (NOR), and enrofloxacin (ENR) were higher than other QNs. The ∑QN concentration in all species was 11.3-321 ng/g dw. The TMFs for ENR and NOR were trophic magnification, while for FLU/OFL it was trophic dilution. The PBCS showed spatial-temporal variation, with a range of 0.6977-0.7910. The TMFs of ENR, FLU, and OFL were significantly positively correlated with PBCS. Phytoplankton and macrophyte biomasses showed indirect impact on the TMFs of QNs by directly influencing the PBCS. Therefore, the PBCS was the direct influencing factor for the TMFs of chemicals.
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Antibacterianos , Monitoreo del Ambiente , Cadena Alimentaria , Lagos , Contaminantes Químicos del Agua , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/metabolismo , Animales , Quinolonas , ChinaRESUMEN
Fatal familial insomnia,an autosomal dominant prion disease,is rare.We reported the clinical symptoms,examination results,diagnosis,treatment,and prognosis of a patient who was diagnosed with fatal familial insomnia.Furthermore,we described the unique clinical manifestations that involuntary movements and laryngeal stridor were significantly correlated with postural changes,aiming to provide reference for the clinical diagnosis,treatment,and research of the disease in the future.
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Discinesias , Insomnio Familiar Fatal , HumanosRESUMEN
Rivers as a critical sink for antibiotic resistance genes (ARGs), and the distribution and spread of ARGs are related to environmental factors, human activities, and biotic factors (e.g. mobile genetic elements (MGEs)). However, the potential link among ARGs, microbial community, and MGEs in rivers under different antibiotic concentration and human activities remains unclear. In this study, 2 urban rivers (URs), 1 rural-urban river (RUR), and 2 rural rivers (RRs) were investigated to identify the spatial-temporal variation and driving force of ARGs. The total concentration of quinolones (QNs) was 160.1-2151 ng·g-1 in URs, 23.34-1188 ng·g-1 in RUR, and 16.39-85.98 ng·g-1 in RRs. Total population (TP), gross domestic production (GDP), sewage, industrial enterprise (IE), and IEGDP appeared significantly spatial difference in URs, RUR, and RRs. In terms of ARGs, 145-161 subtypes were detected in URs, 59-61 subtypes in RURs, and 46-79 subtypes in RRs. For MGEs, 55-60 MGEs subtypes were detected in URs, 29-30 subtypes in RUR, and 29-35 subtypes in RRs. Significantly positive correlation between MGEs and ARGs were found in these rivers. More ARGs subtypes were related to MGEs in URs than those in RUR and RRs. Overall, MGEs and QNs showed significantly direct positive impact on the abundance of ARGs in all rivers, while microbial community was significantly positive impact on the ARGs abundance in URs and RUR. The ARGs abundance in URs/RUR were directly positive influenced by microbial community/MGEs/socioeconomic elements (SEs)/QNs, while those in RRs were directly positive influenced by QNs/MGEs and indirectly positive impacted by SEs. Most QNs resistance risk showed significantly positive correlation with the abundance of ARGs types. Therefore, not only need to consider the concentration of antibiotics, but also should pay more attention to SEs and MGEs in antibiotics risk management and control.
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Microbiota , Quinolonas , Humanos , Antibacterianos/farmacología , Genes Bacterianos , Ríos , Farmacorresistencia Microbiana/genética , Actividades Humanas , Secuencias Repetitivas EsparcidasRESUMEN
The aim of this study was to explore the potential of commercial lactic acid bacteria (LAB) as probiotic starters in fermented sausages. We initially investigated the growth activity, acid production capability, and tolerance to fermentation conditions of Lactobacillus sakei, Lactiplantibacillus plantarum, and Pediococcus pentosaceus. All three LAB strains proved viable as starters for fermented sausages. Subsequently, we explored their potential as probiotics based on their antibacterial and antioxidant capabilities. L. plantarum exhibited stronger inhibition against Escherichia coli and Staphylococcus aureus. All three strains displayed antioxidant abilities, with cell-free supernatants showing a higher antioxidant activity compared to intact cells and cell-free extracts. Moreover, the activities of superoxide dismutase, glutathione peroxidase, and catalase were stronger in the cell-free supernatant, cell-free extract, and intact cell, respectively. Finally, we individually and collectively inoculated these three LAB strains into sausages to investigate their impact on quality during the fermentation process. External starters significantly reduced pH, thiobarbituric acid reactive substances, and sodium nitrite levels. The improvements in color and texture had positive effects, with the L. plantarum inoculation achieving higher sensory scores. Overall, all three LAB strains show promise as probiotic fermentation starters in sausage production.
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Increasing attention has been paid to the heavy metal pollution in groundwater. The source analysis and risk assessment of heavy metals will provide data and method support for the targeted control of heavy metal pollution in groundwater. In this study, 20 sampling sites were selected in Shijiazhuang City. The APCS-MLR model and health risk model were applied to analyze and evaluate the pollution sources and health risks of 10 types of heavy metals in the groundwater of Shijiazhuang. The results showed that â the mean concentration of heavy metals in groundwater followed the order of Fe>Zn>Mn>Cu>Al>Pb>Cr>As>Cd>Hg, and the mean ρ(Fe) and ρ(Pb) were 260.3 µg·L-1 and 10.01 µg·L-1, respectively. According to the results of the single factor and Nemerow index, Pb, Fe, and Cd primarily contributed to the heavy metal pollution in the groundwater. â¡ The concentration of heavy metals ranged from 47.30 to 2560 µg·L-1. In terms of spatial distribution, the highest concentration appeared at S3 (2560 µg·L-1), whereas the lowest concentration was at S9 (47.30 µg·L-1). ⢠Source analysis results showed that industrial and agricultural activities, transportation emission, and geological background were the major heavy metal sources, among which the contribution of industrial and agricultural activities was the highest (47.83%). ⣠The industrial-agricultural activities posed a potential threat to adults (HI>1); however, the non-cancer and the cancer risks of other sources for both adults and children were at an acceptable level (HI<1) and potential threat level, respectively; industrial-agricultural activities were the major source of non-cancer (adults:52.46%, children:52.45%) and cancer risks (adults:65.22%, children:65.69%), among which Cd and As showed high cancer risk. Therefore, to ensure the safety of the groundwater environment, strictly controlling the pollution sources and further strengthening the risk control of heavy metal pollution in groundwater are necessary.
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Agua Subterránea , Metales Pesados , Adulto , Niño , Humanos , Cadmio , Plomo , Medición de Riesgo , ChinaRESUMEN
The current situation of antibiotic pollution in lakes is critical. At present, most of the previous studies on antibiotics in lakes have focused on the spatiotemporal distribution and risk assessment, while less attention has been paid to the source apportionment. Ultra-high performance liquid chromatography-mass spectrometry was used to determine the concentration of tetracyclines (TCs), sulfonamides (SAs), and quinolones (QNs) in the samples. The source apportionment and source-specific risk of typical antibiotics in the study area were analyzed using the combination of a PMF model and risk quotients (RQ). The results showed that â the total concentrations of target antibiotics (Σ antibiotics) ranged from ND to 2635 ng·L-1 for surface water and from ND to 259.8 ng·g-1 for sediments. â¡ The spatial distribution of QNs in surface water decreased from west to east, SAs decreased from middle to north and south, and TCs increased from middle to north and south. In the sediment, QNs decreased from middle to east and west, whereas SAs and TCs increased from east to west. ⢠Aquaculture was the major antibiotic source, accounting for the highest proportion (33.2%), followed by sewage treatment plants (29.2%), livestock activities (18.9%), and domestic sewage (18.7%). ⣠The ecological risk assessment results showed that enrofloxacin and flumequine were at a medium-high risk level. ⤠For the spatial distribution of source-specific risk, the results showed that the aquaculture at S1 was at a high risk level, whereas the source-specific risks for other sites were at a medium-low risk level. In terms of source types, aquaculture was at a medium-high risk level, whereas the other sources were at a medium-low risk level. Therefore, considering the major sources and source-specific risk level of antibiotics, more precise and scientific antibiotic risk control should be adopted in Baiyangdian Lake.
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Antibacterianos , Lagos , Aguas del Alcantarillado , Sulfanilamida , Enrofloxacina , SulfonamidasRESUMEN
PURPOSE: To explore whether glycated albumin (GA) or fasting plasma glucose (FPG), both routinely monitored during patients' hospital stay, can be used to predict post-transplantation diabetes mellitus (PTDM). METHODS: All kidney transplantation recipients (KTRs) from January 2017 to December 2018 were followed-up for 1 year. PTDM was diagnosed from day 45 post-operation to 1 year. When the completeness was above 80%, FPG or GA data on the day was selected, analyzed, and presented as range parameters and standard deviation (SD) and compared between PTDM and non-PTDM groups in fluctuation and stable periods. The predictive cut-off values were determined via receiver operating characteristic (ROC) analysis. The PTDM combined predictive mode, formed by the independent risk factors derived from logistic regression analyses, was compared with each independent risk factor with the independent ROC curve test. RESULTS: Among 536 KTRs, 38 patients developed PTDM up to 1 year post-operatively. The family history diabetes mellitus (OR, 3.21; P = 0.035), the FPG SD in fluctuation period >2.09 mmol/L (OR, 3.06; P = 0.002), and the FPG maximum in stable period >5.08 mmol/L (OR, 6.85; P < 0.001) were the PTDM independent risk factors. The discrimination of the combined mode (area under the curve = 0.81, sensitivity = 73.68%, and specificity = 76.31%) was higher than each prediction (P < 0.05). CONCLUSIONS: The FPG standard deviation during the fluctuation period, FPG maximum during the stable period, and family history diabetes mellitus predicted PTDM with good discrimination and potential routine clinical use.
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Diabetes Mellitus , Trasplante de Riñón , Humanos , Glucemia , Trasplante de Riñón/efectos adversos , Prueba de Tolerancia a la Glucosa , Diabetes Mellitus/epidemiología , Diabetes Mellitus/etiología , Factores de Riesgo , AyunoRESUMEN
Statins play an important role in the treatment of diabetic nephropathy. Increasing attention has been given to the relationship between statins and insulin resistance, but many randomized controlled trials confirm that the therapeutic effects of statins on diabetic nephropathy are more beneficial than harmful. However, further confirmation of whether the beneficial effects of chronic statin administration on diabetic nephropathy outweigh the detrimental effects is urgently needed. Here, we find that long-term statin administration may increase insulin resistance, interfere with lipid metabolism, leads to inflammation and fibrosis, and ultimately fuel diabetic nephropathy progression in diabetic mice. Mechanistically, activation of insulin-regulated phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin signaling pathway leads to increased fatty acid synthesis. Furthermore, statins administration increases lipid uptake and inhibits fatty acid oxidation, leading to lipid deposition. Here we show that long-term statins administration exacerbates diabetic nephropathy via ectopic fat deposition in diabetic mice.
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Diabetes Mellitus Experimental , Nefropatías Diabéticas , Inhibidores de Hidroximetilglutaril-CoA Reductasas , Hipercolesterolemia , Resistencia a la Insulina , Animales , Ratones , Diabetes Mellitus Experimental/complicaciones , Diabetes Mellitus Experimental/metabolismo , Nefropatías Diabéticas/inducido químicamente , Nefropatías Diabéticas/tratamiento farmacológico , Nefropatías Diabéticas/metabolismo , Ácidos Grasos , Inhibidores de Hidroximetilglutaril-CoA Reductasas/efectos adversos , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Lípidos , MamíferosRESUMEN
Background: Delayed graft function (DGF) commonly occurs after kidney transplantation, but no clinical predictors for guiding post-transplant management are available. Materials and methods: Data including demographics, surgery, anesthesia, postoperative day 1 serum cystatin C (S-CysC) level, kidney functions, and postoperative complications in 603 kidney transplant recipients who met the enrollment criteria from January 2017 to December 2018 were collected and analyzed to form the Intention-To-Treat (ITT) set. All perioperative data were screened using the least absolute shrinkage and selection operator. The discrimination, calibration, and clinical effectiveness of the predictor were verified with area under curve (AUC), calibration plot, clinical decision curve, and impact curve. The predictor was trained in Per-Protocol set, validated in the ITT set, and its stability was further tested in the bootstrap resample data. Result: Patients with DGF had significantly higher postoperative day 1 S-CysC level (4.2 ± 1.2 vs. 2.8 ± 0.9 mg/L; P < 0.001), serum creatinine level (821.1 ± 301.7 vs. 554.3 ± 223.2 µmol/L; P < 0.001) and dialysis postoperative (74 [82.2%] vs. 25 [5.9%]; P < 0.001) compared with patients without DGF. Among 41 potential predictors, S-CysC was the most effective in the parsimonious model, and its diagnostic cut-off value was 3.80 mg/L with the risk score (OR, 13.45; 95% CI, 8.02-22.57; P < 0.001). Its specificity and sensitivity indicated by AUC was 0.832 (95% CI, 0.779-0.884; P < 0.001) with well fit calibration. S-CysC yielded up to 50% of clinical benefit rate with 1:4 of cost/benefit ratio. Conclusion: The postoperative day 1 S-CysC level predicts DGF and may be used as a predictor of DGF but warrants further study.
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Here we demonstrate an ultra-compact 8-channel sinusoidal silicon waveguide array for an optical phased array. In our device, based on sinusoidal bending, the cross talk (CT) between waveguides can be efficiently reduced with a waveguide pitch of only 695â nm. For the transverse electric (TE) mode, the simulation results show that the insertion loss (IL) of the 100-µm-long device is 0.1â dB and the CT between all waveguides is lower than -25â dB at 1550â nm. In the measurements, an IL of less than 1â dB and CT lower than -18â dB are obtained. Since the pitch is related to the beam-steering range and power consumption of the optical phased array, such an ultra-compact device could potentially be a good candidate to build the emitter for an energy-efficient optical phased array with a large field of view.
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Glioblastoma (GBM) is the most common malignant primary brain tumor with a poor prognosis. The current standard treatment regimen represented by temozolomide/radiotherapy has an average survival time of 14.6 months, while the 5-year survival rate is still less than 5%. New therapeutics are still highly needed to improve the therapeutic outcome of GBM treatment. The blood-brain barrier (BBB) is the main barrier that prevents therapeutic drugs from reaching the brain. Nanotechnologies that enable drug delivery across the BBB hold great promise for the treatment of GBM. This review summarizes various drug delivery systems used to treat glioma and focuses on their approaches for overcoming the BBB to enhance the accumulation of small molecules, protein and gene drugs, etc. in the brain.
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In this work, an ultra-sharp multimode waveguide bend (MWB) based on gradient shallowly etched grooves is proposed and demonstrated. With a bending radius of only 5.6 µm, our shallowly-etched-groove multimode waveguide bend (SMWB) can enable low excess loss and low-crosstalk propagation with the four lowest-order TE mode-channels, simultaneously. In the simulation, the excess losses of the proposed 90°- SMWB for TE0-TE3 are all below 0.46 dB and the inter-mode crosstalks are lower than -18 dB in 1500 nm-1600 nm. Furthermore, the measured results of the fabricated 90°- SMWB show that the excess losses for TE0-TE3 are less than 1 dB and the inter-mode crosstalks are all below -14 dB in 1510 nm-1580 nm. Such a proposed device thus provides a promising solution for ultra-compact MWBs in multimode silicon photonics.
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In this work, an ultra-compact low-crosstalk sinusoidal silicon waveguide array is proposed and analyzed. We first design a pair of low-crosstalk sinusoidal silicon waveguides with a pitch of 695 nm, where the sinusoidal bends are the key to reduce the crosstalk between waveguides. Then, based on this idea, we propose a low-crosstalk sinusoidal silicon waveguide array with a 695 nm pitch. The simulation results show that for an array length of 100 µm, the insertion loss is as low as 0.08 dB, and the crosstalk is lower than -26 dB at 1550 nm. The 695 nm pitch waveguide array also exhibits a favorable fabrication error tolerance when taking into account the waveguide width variations in practice. Moreover, within the acceptable range of crosstalk, the center-to-center distance between adjacent waveguides of this array can be further reduced to 615 nm. Since the pitch is related to the power consumption and beam-steering range of the optical phased array, our design provides an effective method to build the emitter for an energy-efficient optical phased array with a large field of view.