Stimulated-responsive refractive-diffractive biological hydrogel micro-optical element enabling achromatism via femtosecond laser lithography.

Herein, we report a novel biological hydrogel-based achromatic refractive-diffractive micro-optical element with single-material apochromatism. Benefiting from the stimulated responsive property of the hydrogel, pH modulation yielded swelling and affected the refractive index of the element, enabling multi-wavelength focusing performance tuning and chromatic aberration adjustment. Using femtosecond laser lithography, we fabricated a separate hydrogel microlens and Fresnel zone plate and measured the tunable focusing performance while varying pH; the results were consistent with our simulation results. Furthermore, we designed and fabricated a hydrogel-based achromatic refractive-diffractive micro-optical element and demonstrated achromatism with respect to three wavelengths using only one material consisting of a microlens and a Fresnel zone plate. We characterized the optical focusing properties and observed smaller chromatic aberration. The potential applications of such hybrid microoptical elements include biomedical imaging and optical biology sensing.

Contribution of traditional deep fermentation to volatile metabolites and odor characteristics of Wuyi rock tea.

Fermentation is extremely important for the formation of the special flavor of Wuyi rock tea. This study determined volatile metabolite contents using GC-MS technique and futher analyzed their odor characteristics during the traditional deep fermentation technology of Wuyi rock tea. The results showed that 17 characteristic compounds significantly changed during the first stage of the preliminary processing, namely fresh leaves, withering and fermentation. The key to the formation of floral aroma lied in dihydromyrcenol, and the woody aroma derived from six terpenoids, and their synthesis depended on dihydromyrcenol content. The fruity aroma was dominated by six esters, and the fruity aroma mainly came from (Z) -3-hexen-1-yl butyrate, (E) -3-hexen-1-yl butyrate and 5-Hexenyl butyrate. This study provided an important theoretical and practical basis for improving the preliminary processing of Wuyi rock tea.

Phase-Type Fresnel Zone Plate with Multi-Wavelength Imaging Embedded in Fluoroaluminate Glass Fabricated via Ultraviolet Femtosecond Laser Lithography.

Herein, we report a novel optical glass material, fluoroaluminate (AlF3) glass, with excellent optical transmittance from ultraviolet to infrared wavelength ranges, which provides more options for application in optical devices. Based on its performance, the phase-type Fresnel zone plate (FZP) by ultraviolet femtosecond (fs) laser-inscribed lithography is achieved, which induces the refractive index change by fs-laser tailoring. The realization of ultraviolet fs-laser fabrication inside glass can benefit from the excellent optical performance of the AlF3 glass. Compared with traditional surface-etching micro-optical elements, the phase-type FZP based on AlF3 glass exhibits a clear and well-defined geometry and presents perfect environmental suitability without surface roughness problems. Additionally, optical focusing and multi-wavelength imaging can be easily obtained. Phase-type FZP embedded in AlF3 glass has great potential applications in the imaging and focusing in glass-integrated photonics, especially for the ultraviolet wavelength range.

Two-dimensional suprawavelength periodic surface structuring of a ZnO single crystal with a UV femtosecond laser.

Herein, we report on the one-step formation of a novel microstructure on the surface of crystalline ZnO in ambient air excited by a single femtosecond laser beam (central wavelength 400 nm, pulse duration 35fs), which has photon energy close to the bandgap of ZnO. A two-dimensional surface structure with a controlled period of ∼2-6 µm is observed, with its orientation independent on the status of laser polarization (linear, circular, or elliptical polarization). We find that the orientation of this two-dimensional structure is defined by the direction of the crystal a and c axes. This structural period of ∼2-6 micrometers and the independence of its orientation on the laser polarization are in sharp contrast with the traditional laser induced periodic surface structure (LIPSS). In the meantime, surface cracks with a feature size of ∼30 nm are observed at the bottom of the valley of the two-dimensional structure and theoretical results show there exists strong electric field enhancement on the cracks under 400 nm femtosecond laser irradiation. In view of these unusual features, we attribute the formation of this two-dimensional structure to the mechanical cracking of the ZnO crystal along its (11-20) and (0001) planes induced by the multiple-cyclic heating due to linear absorption of the femtosecond pulses.

Impact of regulatory T cells on the prognosis of hepatocellular carcinoma: A protocol for systematic review and meta analysis.

BACKGROUND: This meta-analysis aimed to systematically review current available literature to assess the impact of regulatory T cells (Tregs) on the prognosis of hepatocellular carcinoma (HCC). METHODS: We will browse the online databases of PubMed and Cochrane Library. The summary hazard ratio (HR) and their 95% confidence intervals (CIs) will be combined to present the value reported in the study. CONCLUSION: Our meta-analysis will provide useful guidance in treatment of HCC based on the reported evidences regarding the impact of Tregs on the prognosis of HCC. OSF REGISTRATION NUMBER: 10.17605/OSF.IO/3Q8PW.

Femtosecond-scale all-optical switching in oxyfluorogallate glass induced by nonlinear multiphoton absorption.

Herein, all-optical switching based on a new type of oxyfluorogallate glass with high switching efficiency and ultrafast response time was reported in the near-infrared wavelength range, which is of great importance for applications in optical telecommunication. The structural and optical properties, as well as the nonlinear optical effects, of the oxyfluorogallate glass were investigated, demonstrating a good figure of merit applicable to nonlinear optical devices. Using pump-probe experiments, we found that the switching time in the oxyfluorogallate glass due to nonlinear multiphoton absorption was approximately 350 fs, which was limited by the pulse duration of the near-infrared probe pulse. Additionally, the largest on-off amplitude of this optical switching device could reach ∼12%, which is in sharp contrast to that of quartz glass. Thus, this study provides a suitable material for the manufacture of integrated photonic devices, which are crucial for promoting the application of glass on-chip photonics.

Smart bio-gel optofluidic Mach-Zehnder interferometers multiphoton-lithographically customized with chemo-mechanical-opto transduction and bio-triggered degradation.

Stimulus-responsive optical polymers, especially gels, are enabling new-concept energy-transducing "smart" optics. Full exploitation of their molecule-derived tuning and integration with traditional micro/nano-optics/optoelectronics rely on the implementation of devices by advanced "intelligent" micro/nano-manufacturing technologies, especially photolithographies with wide compatibility. In light of the increasing need for an organic combination of smart optical materials and digital micro/nano-manufacturing, novel "smart" optical micro-switches, namely, stimulus-actuated Mach-Zehnder interferometers as a proof-of-concept demonstration, were prototyped with protein-based hydrogels via aqueous multiphoton femtosecond laser direct writing (FsLDW). Protein-based Mach-Zehnder-interferometric smart optical devices here display a morphological quality sufficient for optical applications (average surface roughness ≤∼20 nm), nano-precision three-dimensional (3D) geometry of these millimeter-scale devices and purposely structured distribution of photo-crosslinking degree. Moreover, the device configuration was customized with unbalanced branches in which meticulous stimulus-responsive ability can be realized by simply tuning the surrounding chemical stimuli (i.e., Na2SO4 concentration here). The "heterogeneous" configuration with unbalanced branches (i.e., different optical and stimulus-responsive features) exhibits as-designed "smart" switching of propagated near-infrared light (∼808 nm). These capabilities, along with total biodegradation, indicate the application promise of this gel-based optic construction strategy towards novel "intelligent", bio/eco-friendly, self-tuning or sensing photonic integrated systems like optofluidics.

Near-field imaging of the multi-resonant mode induced broadband tunable metamaterial absorber.

Metamaterial absorbers with tunability have broad prospects for mid-infrared absorption applications. While various methods have been proposed to control absorption, how to analyse and present the physical image of absorption mechanism in depth is still expected and meaningful. Here, we present experimental spatial near-field distributions of a multi-resonant mode induced broadband tunable metamaterial absorber by using near-field optical microscopy. The absorber is constructed by a metal double-sized unit cell and a metallic mirror separated by a thin Ge2Sb2Te5 (GST) spacer. To clearly obtain the physical images, we used a hybrid unit cell consisting of four square resonators to produce two absorption peaks at 7.8 µm and 8.3 µm. The resonance central-wavelength exhibits a redshift while switching the GST thin film from amorphous to crystalline phase. The near-field amplitude and phase optical responses of the absorber are directly observed at absorption frequencies when GST is in both phases, respectively. This work will pave the way for the fundamental science field and inspire potential applications in optical tunable absorption control.

Double-layer metal mesh etched by femtosecond laser for high-performance electromagnetic interference shielding window.

An excellent transparent electromagnetic interference (EMI) shielding window is proposed and demonstrated theoretically and experimentally. The window is composed of double layers of Au-Ni composite mesh, separated by the quartz-glass substrate. The simulation exhibits that the shielding effectiveness (SE) of the double-layer mesh can be improved by increasing the thickness of the substrate in the low frequency range far below the first interfere valley. The measured SE of the proposed structure reaches over 37.61 dB covering an ultra-wide frequency ranging from 150 MHz to 5 GHz, with a maximal SE of 75.84 dB at 3.58 GHz, while the average optical transmittance of the double-layer mesh maintains ∼76.35% at 400-900 nm. Moreover, femtosecond laser direct writing processing technology is used to manufacture the double-layer metal grids, the fabricated grids are not easy to be scuffed off and has a longer operating life. Such a high-performance EMI shielding window has great potential applications in precision optical monitoring instrument and military devices.

Homology modeling and epitope prediction of Der f 33.

Dermatophagoides farinae (Der f), one of the main species of house dust mites, produces more than 30 allergens. A recently identified allergen belonging to the alpha-tubulin protein family, Der f 33, has not been characterized in detail. In this study, we used bioinformatics tools to construct the secondary and tertiary structures and predict the B and T cell epitopes of Der f 33. First, protein attribution, protein patterns, and physicochemical properties were predicted. Then, a reasonable tertiary structure was constructed by homology modeling. In addition, six B cell epitopes (amino acid positions 34-45, 63-67, 103-108, 224-230, 308-316, and 365-377) and four T cell epitopes (positions 178-186, 241-249, 335-343, and 402-410) were predicted. These results established a theoretical basis for further studies and eventual epitope-based vaccine design against Der f 33.

Belowground Interactions Impact the Soil Bacterial Community, Soil Fertility, and Crop Yield in Maize/Peanut Intercropping Systems.

Intercropping has been widely used to control disease and improve yield in agriculture. In this study, maize and peanut were used for non-separation intercropping (NS), semi-separation intercropping (SS) using a nylon net, and complete separation intercropping (CS) using a plastic sheet. In field experiments, two-year land equivalent ratios (LERs) showed yield advantages due to belowground interactions when using NS and SS patterns as compared to monoculture. In contrast, intercropping without belowground interactions (CS) showed a yield disadvantage. Meanwhile, in pot experiments, belowground interactions (found in NS and SS) improved levels of soil-available nutrients (nitrogen (N) and phosphorus (P)) and enzymes (urease and acid phosphomonoesterase) as compared to intercropping without belowground interactions (CS). Soil bacterial community assay showed that soil bacterial communities in the NS and SS crops clustered together and were considerably different from the CS crops. The diversity of bacterial communities was significantly improved in soils with NS and SS. The abundance of beneficial bacteria, which have the functions of P-solubilization, pathogen suppression, and N-cycling, was improved in maize and peanut soils due to belowground interactions through intercropping. Among these bacteria, numbers of Bacillus, Brevibacillusbrevis, and Paenibacillus were mainly increased in the maize rhizosphere. Burkholderia, Pseudomonas, and Rhizobium were mainly increased in the peanut rhizosphere. In conclusion, using maize and peanut intercropping, belowground interactions increased the numbers of beneficial bacteria in the soil and improved the diversity of the bacterial community, which was conducive to improving soil nutrient (N and P) supply capacity and soil microecosystem stability.

Homology modeling and epitope prediction of Der f 33

Dermatophagoides farinae (Der f), one of the main species of house dust mites, produces more than 30 allergens. A recently identified allergen belonging to the alpha-tubulin protein family, Der f 33, has not been characterized in detail. In this study, we used bioinformatics tools to construct the secondary and tertiary structures and predict the B and T cell epitopes of Der f 33. First, protein attribution, protein patterns, and physicochemical properties were predicted. Then, a reasonable tertiary structure was constructed by homology modeling. In addition, six B cell epitopes (amino acid positions 34-45, 63-67, 103-108, 224-230, 308-316, and 365-377) and four T cell epitopes (positions 178-186, 241-249, 335-343, and 402-410) were predicted. These results established a theoretical basis for further studies and eventual epitope-based vaccine design against Der f 33.

Temperature dependent thermal conductivity and transition mechanism in amorphous and crystalline Sb2Te3 thin films.

Sb2Te3 thin films are widely used in high density optical and electronic storage, high-resolution greyscale image recording, and laser thermal lithography. Thermal conductivity and its temperature dependence are critical factors that affect the application performance of thin films. This work aims to evaluate the temperature dependence of thermal conductivity of crystalline and amorphous Sb2Te3 thin films experimentally and theoretically, and explores into the corresponding mechanism of heat transport. For crystalline Sb2Te3 thin films, the thermal conductivity was found to be 0.35 ± 0.035 W m-1 K-1 and showed weak temperature dependence. The thermal conductivity of amorphous Sb2Te3 thin films at temperatures below ~450 K is about 0.23 ± 0.023 W m-1K-1, mainly arising from the lattice as the electronic contribution is negligible; at temperatures above 450 K, the thermal conductivity experiences an abrupt increase owing to the structural change from amorphous to crystalline state. The work can provide an important guide and reference to the real applications of Sb2Te3 thin films.

Extending resolution of scanning optical microscopy beyond the Abbe limit through the assistance of InSb thin layers.

The resolution of light imaging is required to extend beyond the Abbe limit to the subdiffraction, or even nanoscale. In this Letter, we propose to extend the resolution of scanning optical microscopy (SOM) beyond the Abbe limit as a kind of subdiffraction imaging technology through the assistance of InSb thin layers due to obvious nonlinear saturation absorption and reversible formation of an optical pinhole channel. The results show that the imaging resolution is greatly improved compared with the SOM itself. This work provides a way to improve the resolution of SOM without changing the SOM itself, but through the assistance of InSb thin layers. This is also a simple and practical way to extend the resolution of SOM beyond the Abbe limit.

Yellow-light generation and engineering in zinc-doped cadmium sulfide nanobelts with low-threshold two-photon excitation.

Through a simple doping route with zinc ion as a dopant in cadmium sulfide nanobelts, a bright yellow-colored light was obtained. The detailed chromaticity and brightness of the light can be engineered by the dopant concentration and the pumping power, which are used to control the dominant wavelength to any fine yellow color, and even cover the sodium-yellow-line of 589 nm. The nanobelts were synthesized through a chemical vapor deposition method. The peak shift of the XRD result proves that the zinc ions as a dopant exist in the nanobelts rather than in the ZnCdS alloy formation. Time-resolved photoluminescence of the nanobelt reveals the existence of the defect-related state, which induces a red band to further mix with green band-edge emission to form the yellow light. Moreover, low-threshold two-photon excitation was observed in the proper Zn-doped cadmium sulfide nanobelts. The dopant and pumping power-tuned generation and engineering of the yellow light makes it possible to use this kind of material as yellow light-emitting source.

Monolithic bifocal zone-plate lenses for confocal collimation of laser diodes.

An elliptical monolithic bifocal zone plate as a collimating lens, whose two focal lengths in the orthogonal directions match the different beam waist positions of the fast and slow axes' light from edge-emitting laser diodes, is proposed and experimentally demonstrated by employing femtosecond laser direct writing technology. The high-quality eight-level zone plate exhibits a diffraction efficiency of 92.9%, which is much higher than those ever reported. Shaped by the elliptical lens, the laser diodes' divergence angles are simultaneously reduced from 65° (1134 mrad, fast axis) and 24° (418 mrad, slow axis) to 7.7 and 136.5 mrad, respectively.

Characterization of metaproteomics in crop rhizospheric soil.

Soil rhizospheric metaproteomics is a powerful scientific tool to uncover the interactions between plants and microorganisms in the soil ecosystem. The present study established an extraction method suitable for different soils that could increase the extracted protein content. Close to 1000 separate spots with high reproducibility could be identified in the stained 2-DE gels. Among the spots, 189 spots representing 122 proteins on a 2-DE gel of rice soil samples were successfully identified by MALDI-TOF/TOF-MS. These proteins mainly originated from rice and microorganisms. They were involved in protein, energy, nucleotide, and secondary metabolisms, as well as signal transduction and resistance. Three characteristics of the crop rhizospheric metaproteomics seemed apparent: (1) approximately one-third of the protein spots could not be identified by MALDI-TOF/TOF/MS, (2) the conservative proteins from plants formed a feature distribution of crop rhizospheric metaproteome, and (3) there were very complex interactions between plants and microorganisms existing in a crop rhizospheric soil. Further functional analysis on the identified proteins unveiled various metabolic pathways and signal transductions involved in the soil biotic community. This study provides a paradigm for metaproteomic research on soil biology.

Residual hepatocellular carcinoma after oxaliplatin treatment has increased metastatic potential in a nude mouse model and is attenuated by Songyou Yin.

BACKGROUND: The opposite effects of chemotherapy, which enhance the malignancy of treated cancers such as hepatocellular carcinoma (HCC), are not well understood. We investigated this phenomenon and corresponding mechanisms to develop a novel approach for improving chemotherapy efficacy in HCC. METHODS: Human hepatocellular carcinoma cell lines HepG2 (with low metastatic potential) and MHCC97L (with moderate metastatic potential) were used for the in vitro study. An orthotopic nude mouse model of human HCC was developed using MHCC97L cells. We then assessed the metastatic potential of surviving tumor cells after in vitro and in vivo oxaliplatin treatment. The molecular changes in surviving tumor cells were evaluated by western blot, immunofluorescence, and immunohistochemistry. The Chinese herbal extract Songyou Yin (composed of five herbs) was investigated in vivo to explore its effect on the metastatic potential of oxaliplatin-treated cancer cells. RESULTS: MHCC97L and HepG2 cells surviving oxaliplatin treatment showed enhanced migration and invasion in vitro. Residual HCC after in vivo oxaliplatin treatment demonstrated significantly increased metastasis to the lung (10/12 vs. 3/12) when re-inoculated into the livers of new recipient nude mice. Molecular changes consistent with epithelial-mesenchymal transition (EMT) were observed in oxaliplatin-treated tumor tissues and verified by in vitro experiments. The Chinese herbal extract Songyou Yin (4.2 and 8.4 g/kg) attenuated EMT and inhibited the enhanced metastatic potential of residual HCC in nude mice (6/15 vs. 13/15 and 3/15 vs. 13/15, respectively). CONCLUSIONS: The surviving HCC after oxaliplatin treatment underwent EMT and demonstrated increased metastatic potential. Attenuation of EMT by Songyou Yin may improve the efficacy of chemotherapy in HCC.

Herbal extract "Songyou Yin" inhibits tumor growth and prolongs survival in nude mice bearing human hepatocellular carcinoma xenograft with high metastatic potential.

PURPOSE: Chinese herbs have become a focus of interest in cancer treatment. This study evaluates the effect of the herbal compound extract "Songyou Yin" (containing Salvia miltiorrhiza Bge.-danshen and other four herbs) on hepatocellular carcinoma (HCC). METHODS: Human HCC cell line MHCC97H with high-metastatic potential was employed for in vitro study. In vivo study was conducted in nude mice bearing HCC orthotopic xenograft with MHCC97H. RESULTS: In vitro, "Songyou Yin" caused dramatic attenuation of tumor proliferation by induction of apoptosis that was associated with caspase-3 activation, and inhibit invasiveness of MHCC97H via reducing matrix metalloproteinase-2 (MMP2) activity. In vivo, "Songyou Yin" minimized cancer-related body weight loss of mice bearing tumors without distinct toxicity, and inhibited tumor growth with stepwise increased dosage of "Songyou Yin" and accorded with the expression of proliferating cell nuclear antigen. Moreover, "Songyou Yin" inhibited tumor growth was associated with an increased TUNEL-positive apoptosis as well as a decreased microvessel density and vascular endothelial growth factor (VEGF) abundance, and inhibited tumor invasion via down-regulation of MMP2. The lung metastatic extent was decreased (p < 0.01, compared with control). The life span of nude mice bearing xenografts was 75.0 +/- 3.9 days in "Songyou Yin" group, whereas it was 52.0 +/- 2.3 days in the control (p < 0.001). CONCLUSIONS: Nontoxic herbal compound extract "Songyou Yin" inhibited tumor growth and prolonged survival, via inducing apoptosis and down-regulation of MMP2 and VEGF, which indicated its potential use in patients with advanced HCC.