Phase-matched third-harmonic generation in silicon nitride waveguides.

Third-harmonic generation (THG) in silicon nitride waveguides is an ideal source of coherent visible light, suited for ultrafast pulse characterization, telecom signal monitoring and self-referenced comb generation due to its relatively large nonlinear susceptibility and CMOS compatibility. We demonstrate third-harmonic generation in silicon nitride waveguides where a fundamental transverse mode at 1,596 nm is phase-matched to a TM02 mode at 532 nm, confirmed by the far-field image. We experimentally measure the waveguide width-dependent phase-matched wavelength with a peak-power-normalized conversion efficiency of 5.78 × 10-7 %/W2 over a 660-µm-long interaction length.

siRNA-Mediated BmAurora B Depletion Impedes the Formation of Holocentric Square Spindles in Silkworm Metaphase BmN4 Cells.

Silkworm ovary-derived BmN4 cells rely on chromatin-induced spindle assembly to form microtubule-based square mitotic spindles that ensure accurate segregation of holocentric chromosomes during cell division. The chromosome passenger protein Aurora B regulates chromosomal condensation and segregation, spindle assembly checkpoint activation, and cytokinesis; however, its role in holocentric organisms needs further clarification. This study examined the architecture and dynamics of spindle microtubules during prophase and metaphase in BmN4 cells and those with siRNA-mediated BmAurora B knockdown using immunofluorescence labeling. Anti-α-tubulin and anti-γ-tubulin antibodies revealed faint γ-tubulin signals colocalized with α-tubulin in early prophase during nuclear membrane rupture, which intensified as prophase progressed. At this stage, bright regions of α-tubulin around and on the nuclear membrane surrounding the chromatin suggested the start of microtubules assembling in the microtubule-organizing centers (MTOCs). In metaphase, fewer but larger γ-tubulin foci were detected on both sides of the chromosomes. This resulted in a distinctive multipolar square spindle with holocentric chromosomes aligned at the metaphase plate. siRNA-mediated BmAurora B knockdown significantly reduced the γ-tubulin foci during prophase, impacting microtubule nucleation and spindle structure in metaphase. Spatiotemporal BmAurora B expression analysis provided new insights into the regulation of this mitotic kinase in silkworm larval gonads during gametogenesis. Our results suggest that BmAurora B is crucial for the formation of multipolar square spindles in holocentric insects, possibly through the activation of γ-tubulin ring complexes in multiple centrosome-like MTOCs.

Hands-On Photonic Education Kits: empowering the integrated photonics workforce through practical training.

The Hands-On Photonic Education (HOPE) Kits, developed with AIM Photonics, address the need for skilled workers in integrated photonics. This paper highlights the role of the HOPE Kits in advancing the training ecosystem and bridging the skills gap. The kits include fully packaged photonic integrated circuits (PICs), enabling instructors to educate and train students on PIC testing and characterization. Covering a wide range of devices and circuits, from waveguides to wavelength division multiplexing for data communication, the kits offer a hands-on experience. Engaging with actual PICs, students gain practical insights, enhancing their understanding of key principles, and preparing them for real-world skill sets in integrated photonics.

Fiber array to chip attach using laser fusion splicing for low loss.

With the ever-increasing need for higher data rates, datacom and telecom industries are now migrating to silicon photonics to achieve higher data rates with reduced manufacturing costs. However, the optical packaging of integrated photonic devices with multiple I/O ports remains a slow and expensive process. We introduce an optical packaging technique to attach fiber arrays to a photonic chip in a single shot using CO2 laser fusion splicing. We show a minimum coupling loss of 1.1 dB, 1.5 dB, and 1.4 dB per-facet for 2, 4, and 8-fiber arrays (respectively) fused to the oxide mode converters using a single shot from the CO2 laser.

Junction of ZnmIn2S3+m and bismuth vanadate as Z-scheme photocatalyst for enhanced hydrogen evolution activity: The role of interfacial interactions.

A series of ZnmIn2S3+m photocatalysts were synthesized to show tunable band gap energy with the variation of Zn/S atomic ratio. The junction of ZnmIn2S3+m and BiVO4 led to intimate interfacial contacts. Both experimental and theoretical results implied that electrons flowed from ZnmIn2S3+m to BiVO4 at the ZnmIn2S3+m/BiVO4 interface to form built-in electric field due to the variation of Fermi level, which promised Z scheme charge transfer feature for improving separation of charge carriers for enhanced photocatalytic performance. A higher degree of charge transfer process occurred for Zn2In2S5/BiVO4 heterostructure promised stronger built-in electric field, higher charge separation efficiency and improved photocatalytic activity in comparison to ZnIn2S4/BiVO4 and Zn3In2S6/BiVO4 heterojunctions. The optimal hydrogen production rate of Zn2In2S5/BiVO4 photocatalyst is 8.42 mmol•g-1•h-1 with apparent quantum yield of 22.32 % at 435 nm, which is about 2.2 and 1.5 times higher than that of ZnIn2S4/BiVO4 and Zn3In2S6/BiVO4, respectively.

Enhanced on-chip frequency measurement using weak value amplification.

We present an integrated design to sensitively measure changes in optical frequency using weak value amplification with a multi-mode interferometer. The technique involves introducing a weak perturbation to the system and then post-selecting the data in such a way that the signal is amplified without amplifying the technical noise, as has previously been demonstrated in a free-space setup. We demonstrate the advantages of a Bragg grating with two band gaps for obtaining simultaneous, stable high transmission and high dispersion. The device is more robust and easily scalable than the free-space implementation, and provides amplified sensitivity compared to other methods of measuring changes in optical frequency on a chip, such as an integrated Mach-Zehnder interferometer.

Electrically induced adiabatic frequency conversion in an integrated lithium niobate ring resonator.

Changing the frequency of light outside the laser cavity is essential for an integrated photonics platform, especially when the optical frequency of the on-chip light source is fixed or challenging to be tuned precisely. Previous on-chip frequency conversion demonstrations of multiple GHz have limitations of tuning the shifted frequency continuously. To achieve continuous on-chip optical frequency conversion, we electrically tune a lithium niobate ring resonator to induce adiabatic frequency conversion. In this work, frequency shifts of up to 14.3 GHz are achieved by adjusting the voltage of an RF control. With this technique, we can dynamically control light in a cavity within its photon lifetime by tuning the refractive index of the ring resonator electrically.

Enhanced on-chip phase measurement by inverse weak value amplification.

Optical interferometry plays an essential role in precision metrology such as in gravitational wave detection, gyroscopes, and environmental sensing. Weak value amplification enables reaching the shot-noise-limit of sensitivity, which is difficult for most optical sensors, by amplifying the interferometric signal without amplifying certain technical noises. We implement a generalized form of weak value amplification on an integrated photonic platform with a multi-mode interferometer. Our results pave the way for a more sensitive, robust, and compact platform for measuring phase, which can be adapted to fields such as coherent communications and the quantum domain. In this work, we show a 7 dB signal enhancement in our weak value device over a standard Mach-Zehnder interferometer with equal detected optical power, as well as frequency measurements with 2 kHz sensitivity by adding a ring resonator.

S-scheme bismuth vanadate and carbon nitride integrating with dual-functional bismuth nanoparticles toward co-efficiently removal formaldehyde under full spectrum light.

It is crucial to develop more effective photocatalysts in the field of clean environment. In response, the S-scheme BiVO4/g-C3N4 heterojunction modified by in situ reduced non-noble metal Bi nanoparticles was used to synergistically degrade formaldehyde under full spectral irradiation. The results, that investigated by careful characterizations and density functional theory (DFT) calculations, proved that BiVO4/g-C3N4 form an S-scheme heterojunction, which can effectively improve the separation efficiency of photogenic carriers and maintain the original strong redox capability of semiconductor materials. The SPR effect of Bi elemental substance enhanced the optical response and provided more oxidative species. Thus, the photocatalytic activity of BiVO4/Bi/g-C3N4 was significantly improved through their joint efforts, that the degradation efficiency of HCHO (800 ppm) for 6 h is 96.39% under 300 W Xenon lamp without filter with the pseudo-second-order rate constant of 4.16 ppm-1·h-1 and CO2 selectivity of 98.41%. Surprisingly, the degradation efficiency also reached to 49.35% and 32.23% under visible and near-infrared light irradiation, respectively. Moreover, we also tested its photocatalytic decomposition effect on formaldehyde in coatings, indicating that it has a broad prospect in future coatings applications. This study may provide an expected photocatalyst, an efficient non-noble metal modified S-scheme heterojunction, to degrade volatile organic gases under a broad spectrum light.

Structural Insight on Defect-Rich Tin Oxide for Smart Band Alignment Engineering and Tunable Visible-Light-Driven Hydrogen Evolution.

Herein, a series of defect-rich tin oxides, SnxOy, were synthesized with tunable Sn2+/Sn4+ composition ratio and defect chemistry, aiming to explore the impact of local structural modulation, non-stoichiometric chemistry, and defective center on the modulation of band gap values, band edge potential positions, and photocatalytic hydrogen evolution performance. The phase structure, morphology, surface component, and photoelectric properties were analyzed by multiple testing methods. The modulation of the Sn2+/Sn4+ molar ratio was analyzed by X-ray photoelectron spectroscopy and the spectra of Mossbauer and electron spin resonance, which indicated the existence of interstitial tin and oxygen vacancy, predicting a highly disordered local structure. In addition, the photocatalytic activity was evaluated by water splitting for hydrogen production under visible light. The optimal photocatalytic activity toward H2 production rate reached 58.6 µmol·g-1·h-1 under visible light illumination. However, the photocatalytic activity gradually decreased with an increase of synthetic temperature. Much higher Sn2+/Sn4+ molar ratio in the present defective tin oxide gave rise to more negative band edge potentials for hydrogen production. Meanwhile, the driving force was decreased with the diminished Sn2+. Large amounts of hydroxyl groups, Sn2+, and relatively negative potential of conduction band in non-stoichiometric SnxOy play critical roles in visible light harvesting and photocatalytic water splitting. Furthermore, the relationships among crystal structure, electronic properties, and photocatalytic activities were clarified by theoretical calculation. This work provides a novel strategy for the development of highly efficient photocatalytst by regulating the internal electronic structure and surface defects.

Enhanced photocatalytic activity of Ag/Ag2Ta4O11/g-C3N4 under wide-spectrum-light irradiation: H2 evolution from water reduction without co-catalyst.

Designing a superior and stable catalyst toward H2 evolution under solar light to solve the energy crisis has attracted wide concern. Herein, we have constructed a novel heterojunction photocatalyst Ag/Ag2Ta4O11/g-C3N4 by in situ assembly, which can efficiently split water to generate H2 by utilizing wide-spectrum-light irradiation. Optimal H2 production reaches highly to 253.03 µmol g-1 h-1 under the simulated solar light. Moreover, the catalyst presented well stability by the retained 98% photocatalytic activity and invariable textural structure after five recycling tests. The mechanism of H2 generation over the prepared material was carefully investigated through scanning electron microscope (SEM), transmission electron microscopy (TEM), UV-Vis absorption spectra (UV-Vis), photoluminescence analysis (PL), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance spectra (EPR), and several electrochemical measurements. It is proposed that the carriers are efficiently separated through Ag-mediated Z-scheme route in space, retaining their strong redox ability. Ag particles produced by in situ reduction from the component Ag2Ta4O11 could devote to the quick electron migration as the bridge center, effective solar light harvesting due to their surface plasmon resonance, and excellent stability by inhibiting their agglomeration and elution. This research offers a new idea for constructing full solid Z-scheme photocatalysts under wide-spectrum-light irradiation.

Assembling Bi2MoO6/Ru/g-C3N4 for Highly Effective Oxygen Generation from Water Splitting under Visible-Light Irradiation.

Water oxidation is a kinetically challenging reaction for photocatalytic overall water splitting. Producing one molecule of O2 will consume four electrons, so it is an extremely difficult obstacle for researchers. Here, a Bi2MoO6/Ru/g-C3N4 composite was obtained by a gentle hydrothermal method, which could oxidize water into O2 highly efficiently. The optimal O2 production reached 328.34 µmol·g-1·h-1 under visible light irradiation. Moreover, the catalyst presented excellent stability, as shown by a still sustentative 91.4% photocatalytic activity and invariant textural structure after seven recycling tests. The ternary material had the smallest resistance, which indicated that it has a good photoelectron conductive tunnel, and a rapid transfer route is proposed through Bi2MoO6 → Ru → g-C3N4 → NaIO3 (electron acceptor). The massive holes (h+) with high oxidative potential are surely enriched due to the quick electron migration, being fit for a large promotion of the multiple-electron water oxidative proceedings. Therefore, the metallic Ru provided a powerful bridge for efficient transfer of the interface electrons which could be beneficial to spatial separation of photoexcited carriers without the loss of the high redox capacity. Finally, it is proposed that the Ru-assisted electron transport and constituent synergy in Bi2MoO6/Ru/g-C3N4 composite play crucial roles to its enhanced light utilization, efficient photoelectric conversion property, and high-producing oxygen capability.

Synergistic effects of multi-active sites in silver modified Bi°-BiVO4 toward efficient reduction of aromatic nitrobenzene.

In this work, we report on the preparation of silver nanoparticles modified bismuth/bismuth vanadate (Bi°-BiVO4) catalyst with multi-active sites toward efficient reduction of aromatic nitrobenzene, aiming to tailor the synergistic effects of multi-active sites and specify the underlying catalytic mechanism. The as-prepared catalysts were characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray and X-ray photoelectron spectroscopy. It is observed that Ag nanoparticles with diameter of ˜30 nm were anchored evenly on the surface of rod-shaped BiVO4, which offered multi-active sites to contact with the reactants effectively and transfer interfacial electron to 4-nitrophenol (4-NP) rapidly. The activity factor k of Ag/Bi°-BiVO4 for 4-NP reduction is estimated to ˜3933.4 min-1 g-1, which is much higher than that obtained from pristine BiVO4 catalyst, Bi° and noble metal Ag nanoparticles. According to the experimental results, the reaction mechanism and reaction path of 4-NP reduction for BiVO4, Bi and Ag were studied through the density functional theory (DFT) theoretical calculation, which suggested that they exhibit synergistic catalytic effect in the reaction process. This work may provide a feasible foundation for the mechanism research of semiconductor reduction to 4-nitrophenol.

Effects of products designed to modulate the gut microbiota on hyperlipidaemia.

PURPOSE: Fatalities due to heart and cerebrovascular diseases caused by uncontrolled hyperlipidaemia increase every year; on the other hand, lipid-lowering drugs are known to cause side effects. The gut microbiota has been thoroughly investigated by researchers and consumers, because they have unique functional properties and littler side effects. However, the effects of the gut microbiota remain controversial. We conducted a meta-analysis to assess the effects of products designed to modulate the gut microbiota on various hyperlipidaemias. METHODS: We systematically searched PubMed, Embase, Cochrane Library (Central), and Web of Science for randomized controlled trials (published before June 2017, and those only in English) to compare treatment (products designed to modulate the gut microbiota) versus placebo. Our main endpoints were total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) in serum. We assessed pooled data using a fixed effects model. RESULTS: Of 1337 identified studies, 21 were eligible and included in our analysis (n = 1436 participants). The combined estimate of effect size for the impact of products designed to modulate the gut microbiota on serum TC (WMD - 11.07 mg/dL, 95% CI - 13.72 to - 8.43, p < 0.001), LDL-C (WMD - 10.96 mg/dL, 95% CI - 13.37 to - 8.56, p < 0.001), and HDL-C (WMD 0.72 mg/dL, 95% CI 0.06-1.38, p = 0.032) were statistically significant, while no significant effect was found on TG concentrations (WMD - 0.56 mg/dL, 95% CI - 5.59 to 4.47, p = 0.828). Subgroup analysis showed parallel trials, probiotics, and long-term intervention had better effects on lowering blood lipid levels. CONCLUSION: Products designed to modulate the gut microbiota results in changes of the plasma lipid concentrations and these changes may protect against cardiovascular disease.

Analysis of chemical components in herbal formula Qi Bai Granule by UPLC-ESI-Q-TOF-MS.

Qi Bai Granule (QBG), a traditional Chinese medicine formula for the treatment of idiopathic thrombocytopenic purpura, is composed of seven herbs. It is necessary to learn its chemical composition for quality control. In this study, a method for rapid separation and structural identification of the constituents in QBG was established by UPLC-ESI-Q-TOF-MS in negative and positive ion mode. As a result, 112 compounds, such as triterpenoids, flavonoids and monoterpenes were detected. Based on the retention times, accurate masses, fragment ions, related literatures, and/or authentic standards, 107 compounds were unambiguously identified or tentatively characterized. Additionally, 20% monarch, 50% minister, 5% assistant and 24% guide drugs of 112 compounds were detected, which on the whole was consistent with the compatibility of QBG. The results would provide a scientific basis for the quality control, quantitative analysis and further study in vivo or vitro of QBG.

A highly selective conversion of toxic nitrobenzene to nontoxic aminobenzene by Cu2O/Bi/Bi2MoO6.

Cu2O/Bi/Bi2MoO6, a ternary catalyst, was expertly prepared using an in situ catalytic reduction reaction. All synthetic materials were carefully researched by high-resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ultraviolet-visible diffuse reflection spectra (UV-vis DRS). The elemental Bi was generated from Bi2MoO6 (BM) after a circular reduction catalysis process of 4-nitrophenol (4-NP) and evenly dispersed in the surface of the leaves of BM flower-like spheres, which was simultaneously coated with Cu2O. The multiphase samples achieved highly effective catalytic activity (10 053.6 min-1 g-1) for the conversion of the highly toxic 4-NP to the less toxic aminobenzene, compared to the single phase Cu2O and BM nanoparticles. Moreover, the excellent reusable stability of the compositing samples was confirmed by executing successive recycling experiments. It was proposed that the Bi3+/Bi0 pairs were the key active species which were produced via prompt reduction and oxidation with the help of Cu2O. The active interfacial contact between copper oxide/metallic Bi/BM (Cu2O/Bi/BM) in the designed sandwich structure facilitated the production and maintained the balance of Bi3+/Bi0 pairs, contributing to the enhanced activity and excellent stability.

Switching charge transfer process of carbon nitride and bismuth vanadate by anchoring silver nanoparticle toward cocatalyst free water reduction.

With the aim of exploring and modulating the interfacial charge kinetics, a ternary g-C3N4/Ag/BiVO4 was constructed with excellent photocatalytic performance and preferable stability toward H2 evolution in absence of cocatalyst. Both density functional theory (DFT) and experimental results implied that the type II g-C3N4/BiVO4 composite can be switched to Z-scheme via Ag nanoparticles as the electron shuttle. The optimal photocatalytic H2 yield rate achieved for g-C3N4/Ag/BiVO4 was 57.4 µmol·g-1·h-1, being far surpassed the H2 harvest rate of g-C3N4/BiVO4, Ag/g-C3N4 and g-C3N4, which is 2.9, 14.8 and 1.7 µmol·g-1·h-1, respectively. The apparent quantum efficiency of g-C3N4/Ag/BiVO4 photocatalyst was also determined to be 1.23%. Besides, the photocatalytic performance of g-C3N4/Ag/BiVO4 well preserved over 5 runs in 50 h. The improved H2 production performance is considered as the consequence of promoted segregation of photoexcited charge carriers and SPR effects of Ag nanoparticles. In combination with photocurrent measurement, examination of active species and DFT calculation, it is found that Ag nanoparticles as an electron mediator can highly promote the Z-scheme carrier migration that electrons come from conduction band of BiVO4 will quickly assemble with the photo-induced holes from valence band of g-C3N4, leaving electrons in the conduction band of g-C3N4 and holes in valence band of BiVO4 that could greatly enhance the charge separation efficiency.

Astragaloside IV ameliorates neuroinflammation-induced depressive-like behaviors in mice via the PPARγ/NF-κB/NLRP3 inflammasome axis.

Major depressive disorder is a common but devastating mental disorder, and recent evidence shows that neuroinflammation may play a pivotal role in the etiology of depression. Astragaloside IV (AS-IV) is an active component purifed from Astragalus membranaceus (Fisch) Bge, which has shown anti-inflammatory, anti-oxidative and anti-apoptotic effects. In this study, we explored whether AS-IV produced antidepressant effects via its inhibition of neuroinflammation in mouse models of depression. Depressive-like behaviors including decreased sucrose consumption, reduced locomotor activity and increased immobility time were induced in mice using repeated restraint stress (RRS). We found that administration of AS-IV (16, 32 and 64 mg·kg-1·d-1, ig) significantly attenuated RRS-induced depressive-like behaviors. Furthermore, AS-IV administration significantly reduced the levels of TNF-α and IL-1ß, increased PPARγ expression and GSK3ß phosphorylation, decreased NF-κB phosphorylation, and reduced NOD-, LRR- and pyrin domain-containingprotein 3 (NLRP3) inflammasome and caspase-1 p20 generation in the hippocampus of the mice. LPS-induced depression-like behaviors were induced by LPS injection (1 mg·kg-1·d-1, ip), which were ameliorated by administration of AS-IV (20, 40 mg·kg-1·d-1, ig). The results of the LPS-induced mouse model were in accordance with those acquired from the RRS-induced mouse model: LPS injection significantly increased TNF-α and IL-1ß expression in the mouse hippocampus, which was reversed by administration of AS-IV. Moreover, administration of AS-IV significantly increased PPARγ expression and GSK3ß phosphorylation, and decreased NF-κB phosphorylation and NLRP3 inflammasome. These results suggest that AS-IV is a potential drug against depression, and its antidepressant effects are partially mediated by inhibition of neuroinflammation via the upregulation of PPARγ expression.

Umbelliferone reverses depression-like behavior in chronic unpredictable mild stress-induced rats by attenuating neuronal apoptosis via regulating ROCK/Akt pathway.

There is increasing evidence that major depressive disorder (MDD) is also a progressive neurodegeneration disorder and neuronal damage is the major pathology of MDD. Umbelliferone, a coumarin derivative, was found in a range of plants with proved anti-oxidative, anti-inflammatory and neuroprotective effects. The primary purpose of this investigation was to evaluate whether umbelliferone could confer an antidepressant-like effect on the depressive model in rats developed by chronic unpredictable mild stress (CUMS) and explore the possible mechanism involved in its neuroprotective effects. We found that treatments with umbelliferone (15mg/kg, 30mg/kg) significantly ameliorated CUMS-induced depressive-like behaviors, such as decreased sucrose consumption, reduced locomotor activity and prolonged immobility time. Rats under CUMS stimulation treated with umbelliferone (15mg/kg, 30mg/kg) showed reduced neuronal apoptosis, as well as inhibited inflammatory cytokines levels by down-regulating Rho-associated protein kinase (ROCK) signaling and up-regulating protein kinase B (Akt) signaling. In conclusion, umbelliferone showed neuroprotective effects on CUMS-induced model of depression, which was associated with the inhibition of neuronal apoptosis modulated by ROCK/Akt pathway.

The effect of isoliquiritigenin on learning and memory impairments induced by high-fat diet via inhibiting TNF-α/JNK/IRS signaling.

Isoliquiritigenin (ILG), a chalcone from Glycyrrhiza uralensis, has various biological properties. ILG markedly inhibited inflammation, but the effects on the brain inflammation and insulin resistance induced by high-fat diet (HFD) are still unknown, so our study intended to investigate its effect on cognitive dysfunction induced by HFD and the relevant mechanisms. ICR mice were treated with HFD diet for 8 weeks to induce peripheral insulin resistance prior to being intervened with rosiglitazone, ILG (30, 60 mg/kg). 4 weeks later, Morris Water Maze (MWM) was used to assess the learning and memory, the insulin resistance index was measured, and the brain inflammation cytokines (IL-1ß, TNF-α) were assessed. Meanwhile, the p-JNK, p-IRS Ser(307) protein expressions in the hippocampus were also detected using the western blot to explore the corresponding mechanisms. Our results suggested that ILG could significantly alleviate the cognitive impairments in the MWM test and attenuate peripheral insulin resistance. The IL-1ß, TNF-α levels declined with the administration of ILG, meanwhile the p-IRS Ser(307) expression decreased with the inhibition of p-JNK. In conclusion, ILG could improve the spatial learning and memory lesions induced by HFD via the inhibition of TNF-α/JNK/IRS pathway.