Ultra-broad bandwidth array waveguide grating for high-speed backbone network transmission.

With the rapid development of the backbone network rates, there has been a gradual increase in channel spacing and bandwidth. The C&L band ultra-broad bandwidth array waveguide gratings (AWG) of 60-channel 100 GHz channel spacing are designed and fabricated based on silica waveguide. A new parabolic design is used to achieve ultra-broad bandwidth and good spectrum. For the C band ultra-broad bandwidth AWG, the peak insertion loss, uniformity, 0.5 dB bandwidth, 1 dB bandwidth and 3 dB bandwidth are 2.98 dB, 0.36 dB, 0.614 nm, 0.721 nm and 0.937 nm, respectively. For the L band ultra-broad bandwidth AWG, the peak insertion loss, uniformity, 0.5 dB bandwidth, 1 dB bandwidth and 3 dB bandwidth are 2.91 dB, 0.27 dB, 0.560 nm, 0.665 nm and 0.879 nm, respectively. To ensure ultra-broad bandwidth AWG operation at different temperatures, a temperature control circuit is integrated into the packaging design. It has been observed that the performances remain virtually unchanged within the temperature range of -15 to 65 degree. The ultra-broadband AWGs have been successfully tested to transmit 96 Gbaud signals and can be applied to 600 G/800 G backbone network transmission. By using the C&L ultra-broad bandwidth AWGs of 60-channel 100 GHz channel spacing, the total transmission speed over a single-mode fiber can reach 72Tbps/96Tbps.

Low-loss, ultracompact n-adjustable waveguide bends for photonic integrated circuits.

Countless waveguides have been designed based on four basic bends: circular bend, sine/cosine bend, Euler bend (developed in 1744) and Bezier bend (developed in 1962). This paper proposes an n-adjustable (NA) bend, which has superior properties compared to other basic bends. Simulations and experiments indicate that the NA bends can show lower losses than other basic bends by adjusting n values. The circular bend and Euler bend are special cases of the proposed NA bend as n equals 0 and 1, respectively. The proposed bend are promising candidates for low-loss compact photonic integrated circuits.

Electroporation of SUMO-His-Cre protein triggers a specific recombinase-mediated cassette exchange in HEK 293T cells.

Cre recombinase is a widely-used genetic manipulation of genomic DNA. However, the conventional transfection of the DNA vectors expressing the Cre recombinase or viral transduction method yields low transfection efficiencies or insertion mutagenesis. The present paper evaluated whether the direct protein delivery of Cre recombinase through electroporation can induce the Cre-mediated recombination in the HEK 293T cells. Here, the small ubiquitin-related modifier (SUMO) -tagged His-Cre fusion protein was expressed in a soluble pattern in the Eschrichria coli (E.coli) cells, purified using affinity chromatography, and finally electroporated into the HEK 293T cells. These cells were previously transfected with three different Cre reporter vectors. The electroporation of the HEK 293T cells revealed either the activation of EGFP expression, or a decrease in RFP expression, and a concomitant increase in EGFP expression, indicating a desired recombinase-mediated cassette exchange (RMCE) event (conversion of RFP to EGFP), and a biological activity of the purified SUMO-His-Cre protein. The fusion protein is expected to serve in the Easi-CRISPR-LoxP-mediated genome editing to generate transgenic animal models.

Iron regulatory protein is involved in the immune defense of the Chinese mitten crab Eriocheir sinensis.

Iron homeostasis is vital to organismal health; it is maintained by the iron regulatory protein (IRP)-iron-responsive element (IRE) signaling pathway. In the Chinese mitten crab Eriocheir sinensis, EsFer-1 and EsFer-2 reportedly have a putative IRE, but an IRP has not yet been identified. In this study, we successfully amplified the full-length cDNA of EsIRP using gene cloning and rapid amplification of cDNA ends techniques. The length of this cDNA was 4474 bp, and it included a 2682-bp open reading frame encoding 893 amino acids. Using quantitative real-time PCR, mRNA transcripts of EsIRP were detected in various tissues. The highest and lowest expression level was detected in the muscle and gills, respectively. In response to Staphylococcus aureus and Vibrio parahaemolyticus challenge, the transcription level of EsIRP was downregulated and that of EsFer-1 and EsFer-2 was upregulated in hemocytes. EsIRP knockdown resulted in increased expression of both EsFer-1 and EsFer-2. After EsFer-1 and EsFer-2 knockdown, the bacterial clearance ability of E. sinensis against S. aureus and V. parahaemolyticus was impaired. In conclusion, our results suggest that the IRP-IRE signaling pathway plays an important role in the innate immune system response in E. sinensis.

Optimization of the classical interference visibility of an asymmetric Mach-Zehnder interferometer based on planar lightwave circuit technology.

Silicon-based devices offer great potential for quantum key distribution (QKD) with the benefits of miniaturization, scalability, complexity, and improved performance. Based on the planar lightwave circuit technology, a 200 ps delay-time asymmetric Mach-Zehnder interferometer (AMZI) decoding chip was designed and fabricated that can adjust the power ratio of the two arms by introducing a variable beam splitter. The measured delay time is approximately 200 ps, and the two output pulses' peaks can be balanced by loading an appropriate voltage on the variable beam splitter. The classical interference visibility of the AMZI versus temperature was studied, and it is highly temperature dependent. The interference visibility can reach as high as 99.72% under appropriate temperature control. This AMZI can act as a passive decoder in fiber-based QKD systems.

Two-photon interferences on a silica-on-silicon chip with telecom-band photon pairs generated in a fiber.

We report two-photon interferences on a silica-on-silicon chip of Mach-Zehnder interferometer using telecommunication-band correlated photon pairs. The photon pairs were generated by spontaneous four-waving mixing process in a dispersion-shifted fiber. The integrated chip, which was fabricated by standard silica-on-silicon planar lightwave circuit technology, contained a Mach-Zehnder interferometer with a thermo-optic phase shifter. The insertion loss of the interferometer was less than 1 dB. We demonstrated two-photon interferences with both degenerate- and non-degenerate-frequency photon pairs on the Mach-Zehnder interferometer chip. A high fringe visibility was achieved in the interference with nondegenerate-frequency photons. Properties of quantum interference were demonstrated in the interference with degenerate-frequency photon pairs, which is an important way to manipulate the quantum state. These results show great potential of silica-on-silicon photonic chips in applications for the fiber-chip scheme in quantum networks.

Fabrication of -SO3H-functionalized polyphosphazene-reinforced proton conductive matrix-mixed membranes.

Proton exchange membranes (PEMs) have emerged as very promising membranes for automotive applications because of their notable proton conductivity at low temperatures. These membranes find extensive utilization in fuel cells. Several polymeric materials have been used, but their application is constrained by their expense and intricate synthetic processes. Affordable and efficient synthetic methods for polymeric materials are necessary for the widespread commercial use of PEM technology. The polymeric combination of hexachlorocyclotriphosphazene (HCCP) and 4,4-diamino-2,2-biphenyldisulfonic acid facilitated the synthesis of PP-(PhSO3H)2, a polyphosphazene with built-in -SO3H moieties. Characterization revealed that it was a porous organic polymer with high stability. PP-(PhSO3H)2 exhibited a proton conductivity of up to 8.24 × 10-2 S cm-1 (SD = ±0.031) at 353 K under 98% relative humidity (RH), which was more than two orders of magnitude higher than that of its -SO3H-free analogue, PP-(Ph)2 (2.32 × 10-4 S cm-1) (SD = ±0.019) under identical conditions. Therefore, for application in a PEM fuel cell, PP-(PhSO3H)2-based matrix-mixed membranes (PP-(PhSO3H)2-MMMs) were fabricated by mixing them with polyacrylonitrile (PAN) in various ratios. The proton conductivity could reach up to 6.11 × 10-2 S cm-1 (SD = ±0.0048) at 353 K and 98%RH, when the weight ratio of PP-(PhSO3H)2 : PAN was 3 : 1, the value of which was comparable with those of commercially available electrolytes used in PEM fuel cells. PP-(PhSO3H)2-MMM (3 : 1) had an extended lifetime of reusability. Using phosphazene and bisulfonated multiple-amine modules as precursors, we demonstrated that a porous organic polymer with a highly effective proton-conductive matrix-mixed membrane for PEM fuel cells could be produced readily by an intuitive polymeric reaction.

Genome-wide adenine N6-methylation map reveals epigenomic regulation of lipid accumulation in Nannochloropsis.

Epigenetic marks on histones and DNA, such as DNA methylation at N6-adenine (6mA), play crucial roles in gene expression and genome maintenance, but their deposition and function in microalgae remain largely uncharacterized. Here, we report a genome-wide 6mA map for the model industrial oleaginous microalga Nannochloropsis oceanica produced by single-molecule real-time sequencing. Found in 0.1% of adenines, 6mA sites are mostly enriched at the AGGYV motif, more abundant in transposons and 3' untranslated regions, and associated with active transcription. Moreover, 6mA gradually increases in abundance along the direction of gene transcription and shows special positional enrichment near splicing donor and transcription termination sites. Highly expressed genes tend to show greater 6mA abundance in the gene body than do poorly expressed genes, indicating a positive interaction between 6mA and general transcription factors. Furthermore, knockout of the putative 6mA methylase NO08G00280 by genome editing leads to changes in methylation patterns that are correlated with changes in the expression of molybdenum cofactor, sulfate transporter, glycosyl transferase, and lipase genes that underlie reductions in biomass and oil productivity. By contrast, knockout of the candidate demethylase NO06G02500 results in increased 6mA levels and reduced growth. Unraveling the epigenomic players and their roles in biomass productivity and lipid metabolism lays a foundation for epigenetic engineering of industrial microalgae.

Elucidation of ligninolysis mechanism of a newly isolated white-rot basidiomycete Trametes hirsuta X-13.

BACKGROUND: Lignin is a complex aromatic heteropolymer comprising 15-30% dry weight of the lignocellulose. The complex structural characteristic of lignin renders it difficult for value-added utilization. Exploring efficient lignin-degrading microorganisms and investigating their lignin-degradation mechanisms would be beneficial for promoting lignin valorization. In this study, a newly isolated white-rot basidiomycete, Trametes hirsuta X-13, with capacity to utilize alkaline lignin as the sole substrate was investigated. RESULTS: The analysis of the fermentation properties of T. hirsuta X-13 using alkaline lignin as the sole substrate, including the mycelial growth, activities of ligninolytic enzymes and the rates of lignin degradation and decolorization confirmed its great ligninolysis capacity. The maximum lignin degradation rate reached 39.8% after 11 days of T. hirsuta X-13 treatment, which was higher than that of reported fungi under the same condition. Fourier transform infrared spectrometry (FTIR), gas chromatography-mass spectrometry (GC-MS) scanning electron micrographs (SEM), two-dimensional heteronuclear single quantum coherence NMR analysis (2D-HSQC NMR) collaborated with pyrolysis gas chromatography-mass spectrometry (py-GC/MS) analyses proved that lignin structure was severely deconstructed along with amounts of monomer aromatics generated. Furthermore, according to those chemical analysis, in addition to canonical Cα-Cß breakage, the cleavage of lignin interunit linkages of ß-ß might also occur by T. hirsuta X-13. CONCLUSIONS: This study characterized a newly isolated white-rot basidiomycete T. hirsuta X-13 with impressive alkaline lignin degradation ability and provided mechanistic insight into its ligninolysis mechanism, which will be valuable for the development of lignin valorization strategies.

Expression pattern and functional analysis of the two RING box protein RBX in spermatogenesis of Chinese mitten crab Eriocheir sinensis.

Studies in E. sinensis have shown that ubiquitination mediated by Cullin-RING E3 ligases (CRLs) plays important roles in spermatogenesis. In other species, CRLs are also essential in cell cycle progression, DNA replication, signal transduction, gene transcription, and development. The catalytic RING component, the RING box protein, is an important part of CRLs. However, there have been few studies on CRLs in crustaceans. In this study, we cloned two RING box protein genes from the Chinese mitten crab, Eriocheir sinensis, termed Es-RBX1 and Es-RBX2 The full length Es-RBX1 cDNA comprises 741 nucleotides, and encodes a protein of 124 amino acid residues, whereas the Es-RBX2 cDNA comprises 1325 nucleotides, and encodes a protein of 110 amino acid residues. Bioinformatics analysis showed that the domains and structure of the RBX proteins have been highly conserved during evolution. Quantitative real-time polymerase chain reaction and western blotting showed that Es-RBX1 is highly expressed in the testis, particularly during the spermatocyte stage, whereas Es-RBX2 did not show specific expression in the male reproductive system. Furthermore, Es-RBX1 is mainly distributed in the nucleus, and changed its location with the development of the nucleus. Co-immunoprecipitation showed that Es-RBX1 could bind Cullin4. These results suggested that Es-RBX1 plays a key role in spermatogenesis of E. sinensis though forming a complex with Cullin4.