Lateral GeSn p-i-n photodetectors on insulator prepared by the rapid melting growth method.

In this work, GeSn lateral p-i-n photodetectors (PDs) on insulator were fabricated with an active GeSn layer grown by the rapid melting growth (RMG) method. Taking advantages of the defect-free GeSn strips, GeSn PDs with 5.3% Sn content have low dark current and high responsivities, which are about 0.48, 0.47, and 0.24 A/W for wavelengths of 1550, 1630, and 2000 nm, respectively. The radio frequency of the lateral GeSn PDs was also studied and a 3 dB bandwidth of about 3.8 GHz was achieved. These results indicate that the GeSn grown by the rapid melting growth method is capable of fabricating high-performance Si-based optoelectronic devices.

Efficient Removal of Iodine from Water by a Calix[4]pyrrole-Based Nanofilm.

The efficient removal of radioactive iodine from an aqueous solution is largely dependent on the adsorbent materials employed. In this work, we report a calix[4]pyrrole-based nanofilm and its application for the rapid removal of iodine from water. The nanofilm was synthesized through a confined dynamic condensation of tetra hydrazide calix[4]pyrrole with 1,3,5-tri-(4-formylphenyl) aldehyde at the air/dimethyl sulfoxide (DMSO) interface. The thickness of the obtained nanofilm is ∼35 nm, enabling fast mass transfer and a high ratio of accessible binding sites for iodine. The pseudo-second-order rate constant of the nanofilm for iodine is ∼0.061 g g-1 min-1, 3 orders of magnitude higher than most reported adsorbent materials. Flow-through nanofiltration tests demonstrated that the nanofilm has an adsorption capacity of 1.48 g g-1, a high removal efficiency, and good reusability. The mechanism study revealed that the moieties of Schiff base, pyrrole, and aromatic rings play a key role for binding iodine. We believe this work provides not only a new strategy for the efficient removal of radioactive iodine from water but also new ideas for designing efficient iodine adsorbents.

Interfacially Fabricated Covalent Organic Framework Membranes for Film-based Fluorescence Humidity Sensors and Moisture Driven Actuators.

Rapid, on-site measurement of ppm-level humidity in real time remains a challenge. In this work, we fabricated a few micrometer thick, ß-ketoenamine-linked covalent organic framework (COF) membrane via interfacially confined condensation of 1,3,5-tris-(4-aminophenyl)triazine (TTA) with 1,3,5-tri-formylphloroglucinol (TP). Based on the super-sensitive and reversible response of the COF membrane to water vapor, we developed a high-performance film-based fluorescence humidity sensor, depicting unprecedented detection limit of 0.005 ppm, fast response/recovery (2.2 s/2.0 s), and a detection range from 0.005 to 100 ppm. Remarkably, more than 7,000-time continuous tests showed no observable change in the performance of the sensor. The applicability of the sensor was verified by on-site and real-time monitoring of humidity in a glovebox. The superior performance of the sensor was ascribed to the highly porous structure and unique affinity of the COF membrane to water molecules as they enable fast mass transfer and efficient utilization of the water binding sites. Moreover, based on the remarkable moisture driven deformation of the COF membrane and its composition with the known polyimide films, some conceptual actuators were created. This study brings new ideas to the design of ultra-sensitive film-based fluorescent sensors (FFSs) and high-performance actuators.

Sn component gradient GeSn photodetector with 3†dB bandwidth over 50†GHz for extending L band telecommunication.

In this work, high-performance GeSn photodetectors with a Sn content gradient GeSn layer were fabricated on SOI substrate by CMOS-compatible process for C and L band telecommunication. The active GeSn layer has a Sn component increased from 9 to 10.7% with the controlled relaxation degree up to 84%. The responsivities of GeSn detectors at 1550 nm and 1630 nm are 0.47 A/W and 0.32 A/W under -4 V bias, respectively. Over 50 GHz 3 dB bandwidth with the eye pattern about 70 Gb/s was also evidenced at 1630 nm. These results indicate that the GeSn photodetectors have a promising application for extending the silicon photonics from C band to L band.

Large-area Free-standing Metalloporphyrin-based Covalent Organic Framework Films by Liquid-air Interfacial Polymerization for Oxygen Electrocatalysis.

Synthesizing large-area free-standing covalent organic framework (COF) films is of vital importance for their applications but is still a big challenge. Herein, we reported the synthesis of large metalloporphyrin-based COF films and their applications for oxygen electrocatalysis. The reaction of meso-benzohydrazide-substituted metal porphyrins with tris-aldehyde linkers afforded free-standing COF films at the liquid-air interface. These films can be scaled up to 3000 cm2 area and display great mechanical stability and structural integrity. Importantly, the Co-porphyrin-based films are efficient for electrocatalytic O2 reduction and evolution reactions. A flexible, all-solid-state Zn-air battery was assembled using the films and showed high performance with a charge-discharge voltage gap of 0.88 V at 1 mA cm-2 and high stability under bent conditions (0° to 180°). This work thus presents a strategy to synthesize functionalized COF films with high quality for uses in flexible electronics.

Modeling, analysis, and demonstration of a carrier-injection electro-absorption modulator at 2 µm on Ge-on-Si platform.

In this paper, a carrier-injection electro-absorption modulator (EAM) at 2 µm is demonstrated on Ge-on-Si platform. The EAM shows a compact size and high modulation efficiency due to the strong free-carrier electroabsorption (FCEA) effect in Ge. A modulation depth of 40 dB can be obtained under the injection current of only 420 mA. Small-signal frequency response measurement is performed and a small-signal equivalent circuit model is proposed. Based on reflection coefficients and equivalent circuit, the frequency response of carrier-injection EAM is discussed in detail. The 500 Mbps open eye diagram verifies the data-processing capacity of our EAM at 2 µm wavelength for its application in biological, chemical molecular detection, and infrared imaging systems.

High-speed and high-power germanium photodetector based on a trapezoidal absorber.

A compact high-power germanium photodetector (Ge PD) is experimentally demonstrated by re-engineering light distribution in the absorber. Compared with a conventional Ge PD, the proposed structure shows a DC saturation photocurrent improved by 28.9% and 3 dB bandwidth as high as 49.5 GHz at 0.1 mA. Under the same photocurrent of 10.5 mA, the proposed Ge PD shows a 3 dB bandwidth of 11.1 GHz, which is almost double the conventional Ge PD (5.6 GHz). The 25 Gb/s eye-diagram measurement verifies the improved power handling capability. The compact size and manufacturing simplicity of this structure will enable new applications for integrated silicon photonics.

GeSn resonance cavity enhanced photodetector with gold bottom reflector for the L band optical communication.

In this work, GeSn resonant cavity enhanced (RCE) p-i-n photodetectors (PDs) with 3.7% Sn content in a GeSn layer were fabricated on a silicon on insulator (SOI) substrate. The gold (Au) layer and the deposited SiO2 layer constitute the bottom reflector and top reflector of the RCE detectors, respectively. The GeSn RCE PD has three resonant peaks and its responsivity is improved about 4.5 times at 1630 nm, compared with GeSn PDs without a gold bottom mirror. The cutoff wavelength of GeSn RCE PDs is up to 1820 nm, while it is only 1730 nm for GeSn PDs without a gold reflector. The responsivity of RCE PDs at 1630 nm reaches 0.126 A/W and 3-dB bandwidth at about 36 GHz is achieved. These results indicate that the RCE structure is an effective approach for enhancing the GeSn PD performance operated at the L band.

High-performance waveguide-coupled lateral Ge/Si avalanche photodetector.

A high-performance waveguide-coupled lateral avalanche photodetector (APD) is experimentally demonstrated without silicon epitaxy and charge layer ion implantation. At the wavelength of 1550 nm, it shows a high responsivity of 48 A/W and a gain-bandwidth product (GBP) of 360 GHz. Wide-open eye diagrams at 25 Gbps can be observed at various avalanche gains. These outstanding performances indicate the proposed APD has great potential in high-speed optical transceivers for optical links.

Characteristic and antibacterial effect of a histone H2A and its preliminary roles in extracellular traps in manila clam Ruditapes philippinarum.

In the present study, a histone H2A (designed as RpH2A) was identified and characterized from clam Ruditapes philippinarum, and its open reading frame (ORF) was of 387 bp encoding a polypeptide of 128 amino acids. The deduced amino acid sequence of RpH2A shared high identities ranging from 57.1% to 96.1% with that of other identified H2A. The mRNA expression of RpH2A was up-regulated significantly after Vibrio anguillarum challenge. The recombinant RpH2A protein (rRpH2A) displayed significantly binding affinity to lipopolysaccharide (LPS) and peptidoglycan (PGN) in vitro, and also exhibited antimicrobial properties against Escherichia coli. In addition, the antimicrobial RpH2A was shown to co-localize with extracellular traps (ETs) released from hemocytes induced by E. coli, suggesting that RpH2A might contribute to eliminate invading bacteria in clam ETs. Altogether, our data revealed that RpH2A could function as antimicrobial peptides, which might play a crucial role in the immune responses of hemocytes ETs in clams.

High-power back-to-back dual-absorption germanium photodetector.

A high-power germanium photodetector is designed and fabricated using a cold-wall ultrahigh vacuum chemical vapor deposition. A back-to-back dual-absorption structure improves high-power characteristics by reducing the space-charge effect. Compared to a typical p-i-n photodetector, the saturated photocurrent of the back-to-back dual-absorption photodetector is improved from 16.2 to 21.3 mA at $ - {3}\;{\rm V}$-3V. At a bias voltage of $ - {1}\;{\rm V}$-1V, the dark current is 1.31 µA. The optical responsivities are 0.31 and 0.52 A/W at 1550 and 1310 nm, respectively. The 3 dB bandwidth of 4.14 GHz is achieved at $ - {3}\;{\rm V}$-3V. Theoretically, the 3 dB bandwidth can be further optimized in future device fabrication.

Study of GePb photodetectors for shortwave infrared detection.

Ge0.998Pb0.002 photodetectors (PDs) with a GePb layer grown on n-type Ge (100) substrate by magnetron sputtering epitaxy were fabricated by complementary metal-oxide semiconductor (CMOS)-compatible technology. For Ge0.998Pb0.002 PDs, the room-temperature dark current density at -1 V was 3.3 A/cm2. At room temperature, the GePb PDs demonstrated a longwave cutoff of 2.5 µm and the optical responsivities of GePb PDs ranging from 1500 nm to 2000 nm were measured. A temperature dependence optical characterization of these detectors was conducted and temperature-dependent energy bandgaps of Ge0.998Pb0.002 were derived from the photocurrent spectra.

Peptidoglycan recognition protein of Solen grandis (SgPGRP-S1) mediates immune recognition and bacteria clearance.

Peptidoglycan recognition proteins (PGRPs) are indispensable molecules in innate immunity due to their prominent function in sensing and eliminating invading microorganisms. In the present study, a short type PGRP from razor clam Solen grandis (SgPGRP-S1) was recombinantly expressed and purified to investigate its potential function in innate immunity. As a pattern recognition receptor, recombinant SgPGRP-S1 (rSgPGRP-S1) specifically bind Lys-type and Dap-type peptidoglycan in vitro, but not lipopolysaccharide or ß-glucan. The peptidoglycan binding ability of rSgPGRP-S1 resulted in significant agglutination activity against Gram-negative Escherichia coli and Listonella anguillarum, as well as Gram-positive Micrococcus luteus. Furthermore, rSgPGRP-S1 was bactericidal, significantly suppressing the growth of both E. coli and Gram-positive Staphylococcus aureus. The protein also exhibited strong amidase activity and degraded bacterial peptidoglycan in the presence of Zn2+, suggesting amidase activity might contribute to SgPGRP-S1 antibacterial activity. These results indicate SgPGRP-S1 is multifunctional in innate immunity, mediating both immune recognition and bacteria elimination.

Sialic acid-binding lectins (SABLs) from Solen grandis function as PRRs ensuring immune recognition and bacterial clearance.

Sialic acid-binding lectins (SABLs) are ubiquitous ancient molecules with binding properties to N-acetyl or N-glycolyl carbohydrates, and play crucial roles in both adaptive and innate immune responses. In present study, recombinant protein and antibodies of two SABLs from mollusk Solen grandis (SgSABL-1 and SgSABL-2) were prepared to investigate their functions in innate immunity. The recombinant protein of SgSABL-1 (rSgSABL-1) could bind LPS, PGN and ß-glucan in vitro, while rSgSABL-2 could only bind PGN rather than LPS and ß-glucan. Be coincident with their PAMPs recognition properties, rSgSABL-1 displayed a broad agglutination spectrum towards gram-positive bacteria Micrococcus luteus, gram-negative bacteria Listonella anguillarum and fungi Pichia pastoris, and rSgSABL-2 only showed remarkable agglutinative effect on M. luteus and L. anguillarum. More importantly, after PAMPs recognition, rSgSABL-1 and rSgSABL-2 enhanced phagocytosis as well as encapsulation ability of hemocytes in vitro, and the enhanced encapsulation could be blocked by specific antibodies. All these results indicated that SgSABL-1 and SgSABL-2 functioned as two compensative pattern-recognition receptor (PRRs) with distinct recognition spectrum and involved in the innate immune response of S. grandis.

Lead Induces Genotoxicity via Oxidative Stress and Promoter Methylation of DNA Repair Genes in Human Lymphoblastoid TK6 Cells.

BACKGROUND Lead (Pb) is a widely used metal in modern industry and is regarded as a health hazard. Although lead-induced genotoxicity has been confirmed, the direct evidence that lead induces genotoxicity in human cells and its related mechanisms has not been fully elucidated. In this study, for the first time, we evaluated the genotoxicity induced by lead in human lymphoblastoid TK6 cells. MATERIAL AND METHODS The TK6 cells were incubated with various concentrations of Pb(Ac)2 for 6 h, 12 h, or 24 h. Cell viability was detected by CCK8 assay. Various biochemical markers were assessed by specific kits. Immunofluorescence assay was used to detect g-H2AX foci formation. The promoter methylation was assessed by methylation-specific PCR. The protein levels were determined by Western blot assay. RESULTS The results showed that after exposure to lead, cell viability was obviously decreased and γ-H2AX foci formation was significantly enhanced in TK6 cells. Moreover, the levels of 8-OHdG, ROS, MDA, and GSSG were increased, while the GSH level and SOD activity were decreased in lead-treated TK6 cells. The activation of the Nrf2-ARE signaling pathway was involved in lead-induced oxidative stress in TK6 cells. Finally, the expressions of DNA repair genes XRCC1, hOGG-1, BRCA1, and XPD were inhibited via enhancing their promoter methylation in TK6 cells after exposure to lead. CONCLUSIONS Taken together, our study provides the first published evidence that lead exposure results in DNA damage via promoting oxidative stress and the promoter methylation of DNA repair genes in human lymphoblastoid TK6 cells.

Critical roles of sea cucumber C-type lectin in non-self recognition and bacterial clearance.

C-type lectin is one important pattern recognition receptor (PRR) that plays crucial roles in multiple immune responses. A C-type lectin from sea cucumber Apostichopus japonicus (AjCTL-1) was characterized in the present study. The amino acid sequence of AjCTL-1 shared high similarities with other C-type lectins from invertebrates and vertebrates. The C-type lectin domain (CTLD) of AjCTL-1 contained a Ca(2+)-binding site 2 and four conserved cysteine residues. AjCTL-1 mRNA expression patterns in tissues and after bacterial challenge were then analysed. Quantitative PCR revealed that AjCTL-1 mRNA was widely expressed in the tested tissues of healthy sea cucumber. The highest expression level occurred in gonad followed by body wall, coelomocytes, tentacle, intestinum and longitudinal muscle, and the lowest expression level was in respiratory tree. AjCTL-1 mRNA expression in coelomocytes was significantly induced by gram-negative Listonella anguillarum and gram-positive Micrococcus luteus, with different up-regulation patterns post-challenge. Recombinant AjCTL-1 exhibited the ability to bind peptidoglycan directly, agglutinate M. luteus, Staphylococcus aureus and Escherichia coli, in a Ca(2+)-dependant manner, and enhance the phagocytosis of coelomocytes against E. coli in vitro. The results indicated that AjCTL-1 could act as a PRR in Apostichopus japonicus and had critical roles in non-self recognition and bacterial clearance against invading microbes.

Involvement of a Serpin serine protease inhibitor (OoSerpin) from mollusc Octopus ocellatus in antibacterial response.

Serpin is an important member of serine protease inhibitors (SPIs), which is capable of regulating proteolytic events and involving in a variety of physiological processes. In present study, a Serpin homolog was identified from Octopus ocellatus (designated as OoSerpin). Full-length cDNA of OoSerpin was of 1735 bp, containing a 5' untranslated region of 214 bp, a 3' UTR of 282 bp, and an open reading frame of 1239 bp. The open reading frame encoded a polypeptide of 412 amino acids which has a predicted molecular weight of 46.5 kDa and an isoelectric point of 8.52. The OoSerpin protein shares 37% sequence identity with other Serpins from Mus musculus (NP_941373) and Ixodes scapularis (XP_002407493). The existence of a conserved SERPIN domain strongly suggested that OoSerpin was a member of the Serpin subfamily. Expression patterns of OoSerpin, both in tissues and towards bacterial stimulation, were then characterized. The mRNA of OoSerpin was constitutively expressed at different levels in all tested tissues of untreated O. ocellatus, including mantle (lowest), muscle, renal sac, gill, hemocyte, gonad, systemic heart, and hepatopancreas (highest). The transcriptional level of OoSerpin was significantly up-regulated (P<0.01) in O. ocellatus upon bacterial challenges with Vibrio anguillarum and Micrococcus luteus, indicating its involvement in the antibacterial immune response. Furthermore, rOoSerpin, the recombinant protein of OoSerpin, exhibited strong abilities to inhibit proteinase activities of trypsin and chymotrypsin as well as the growth of Escherichia coli. Our results demonstrate that OoSerpin is a potential antibacterial factor involved in the immune response of O. ocellatus against bacterial infection.

Modification of Microstructure and Mechanical Properties of Extruded AZ91-0.4Ce Magnesium Alloy through Addition of Ca.

The effect of the addition of alkali earth element Ca on the microstructure and mechanical properties of extruded AZ91-0.4Ce-xCa (x = 0, 0.4, 0.8, 1.2 wt.%) alloys was studied by using scanning electron microscopy, transmission electron microscopy, and tensile tests. The results showed that the addition of Ca could significantly refine the second phase and grain size of the extruded AZ91-0.4Ce alloy. The refinement effect was most obvious when 0.8 wt.% of Ca was added, and the recrystallized grain size was 4.75 µm after extrusion. The addition of Ca resulted in the formation of a spherical Al2Ca phase, which effectively suppressed the precipitation of the ß-Mg17Al12 phase, promoted dynamic recrystallization and grain refinement, impeded dislocation motion, and exerted a positive influence on the mechanical properties of the alloy. The yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of the AZ91-0.4Ce-0.8Ca alloy were 238.7 MPa, 338.3 MPa, and 10.8%, respectively.

Fully Reversible and Super-Fast Photo-Induced Morphological Transformation of Nanofilms for High-Performance UV Detection and Light-Driven Actuators.

Flexible and highly ultraviolet (UV) sensitive materials garner considerable attention in wearable devices, adaptive sensors, and light-driven actuators. Herein, a type of nanofilms with unprecedented fully reversible UV responsiveness are successfully constructed. Building upon this discovery, a new system for ultra-fast, sensitive, and reliable UV detection is developed. The system operates by monitoring the displacement of photoinduced macroscopic motions of the nanofilms based composite membranes. The system exhibits exceptional responsiveness to UV light at 375 nm, achieving remarkable response and recovery times of < 0.3 s. Furthermore, it boasts a wide detection range from 2.85 µW cm-2 to 8.30 mW cm-2, along with robust durability. Qualitative UV sensing is accomplished by observing the shape changes of the composite membranes. Moreover, the composite membrane can serve as sunlight-responsive actuators for artificial flowers and smart switches in practical scenarios. The photo-induced motion is ascribed to the cis-trans isomerization of the acylhydrazone bonds, and the rapid and fully reversible shape transformation is supposed to be a synergistic result of the instability of the cis-isomers acylhydrazone bonds and the rebounding property of the networked nanofilms. These findings present a novel strategy for both quantitative and qualitative UV detection.

Identification of a LPS-induced TNF-α factor (LITAF) from mollusk Solen grandis and its expression pattern towards PAMPs stimulation.

Lipopolysaccharide-induced TNF-α factor (LITAF) is one of the most important transcription factors mediating TNF-α transcription. In the present study, a LITAF gene (designated as SgLITAF) was identified from razor clams Solen grandis. The full-length cDNA of SgLITAF was of 1476 bp, encoding a polypeptide of 130 amino acids showed high similarity to other known LITAFs. SgLITAF encoded a LITAF domain and the Zn(2+)-binding motifs in the domain were well conserved. The mRNA transcripts of SgLITAF were detected in all tested tissues of healthy razor clams, including mantle, gill, gonad, hemocytes, muscle and hepatopancreas, and with the highest expression level in hepatopancreas. The expression level of SgLITAF in hemocytes was significantly up-regulated (P < 0.01) after razor clams were stimulated by LPS or ß-1, 3-glucan, but no obvious fluctuation of SgLITAF mRNA expression was observed after PGN stimulation. All the results indicated that there might be a LITAF-regulated TNF-α signaling pathway existing in S. grandis, which involved in the immune response not only against gram-negative bacteria but also towards fungi.