11 research outputs found

    An ultra-stable cryogenic sapphire cavity laser with an instability of 1.9×10161.9\times10^{-16} based on a low vibration level cryostat

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    Cryogenic ultra-stable lasers have extremely low thermal noise limits and frequency drifts, but they are more seriously affected by vibration noise from cryostats. Main material candidates for cryogenic ultra-stable cavities include silicon and sapphire. Although sapphire has many excellent properties at low temperature, the development of sapphire-based cavities is less advanced than that of silicon-based. Using a homemade cryogenic sapphire cavity, we develop an ultra-stable laser source with a frequency instability of 1.9×10161.9\times10^{-16}. This is the best frequency instability level among similar systems using cryogenic sapphire cavities reported so far. Low vibration performance of the cryostat is demonstrated with a two-stage vibration isolation, and the vibration suppression is further improved by different mixing ratio of the gas-liquid helium. With this technique, vibrations at frequencies higher than tens of hertz are greatly suppressed.Comment: 4 pages, 4 figure

    Vibration Property of a Cryogenic Optical Resonator within a Pulse-Tube Cryostat

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    Cryogenic ultrastable laser cavities push laser stability to new levels due to their lower thermal noise limitation. Vibrational noise is one of the major obstacles to achieve a thermal-noise-limited cryogenic ultrastable laser system. Here, we carefully analyze the vibrational noise contribution to the laser frequency. We measure the vibrational noise from the top of the pulse-tube cryocooler down to the experiment space. Major differences emerge between room and cryogenic temperature operation. We cooled a homemade 6 cm sapphire optical resonator down to 3.4 K. Locking a 1064 nm laser to the resonator, we measure a frequency stability of 1.3×10−15. The vibration sensitivities change at different excitation frequencies. The vibrational noise analysis of the laser system paves the way for in situ accurate evaluation of vibrational noise for cryogenic systems. This may help in cryostat design and cryogenic precision measurements

    4D-Printed Hydrogel Actuators through Diffusion-Path Architecture Design

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    Recently, smart hydrogels have garnered considerable attention as biomedical devices, and several approaches have been introduced for their fabrication, including the incorporation of stimulus-responsive additives, utilization of molecular imprinting techniques, and application of multilayered hydrogels. However, the nonuniform properties resulting from these approaches limit the practical applications of hydrogels by causing inconsistent performance and behavior. In this study, we propose a novel approach to manipulating the swelling kinetics of hydrogels by engineering their diffusion-path architecture. By simply adjusting the diffusion path length within the hydrogel, we achieved a significant change in swelling kinetics. This approach enables precise control over the diffusion and transport processes within the hydrogel, resulting in enhanced swelling kinetics when reducing the diffusion path length. Furthermore, by strategically designing the diffusion-path architecture of a 3D-printed hydrogel specimen, we can fabricate smart hydrogel actuators that exhibit reversible shape transformations during swelling and deswelling through a nonequilibrium differential swelling. The proposed approach eliminates the need to modify the spatial properties of hydrogel structures such as cross-linking density, polymer, or additive compositions, thereby achieving uniform properties throughout the hydrogel and creating new possibilities for the development of advanced 4D-printed biomedical devices

    4D-Printed Hydrogel Actuators through Diffusion-Path Architecture Design

    No full text
    Recently, smart hydrogels have garnered considerable attention as biomedical devices, and several approaches have been introduced for their fabrication, including the incorporation of stimulus-responsive additives, utilization of molecular imprinting techniques, and application of multilayered hydrogels. However, the nonuniform properties resulting from these approaches limit the practical applications of hydrogels by causing inconsistent performance and behavior. In this study, we propose a novel approach to manipulating the swelling kinetics of hydrogels by engineering their diffusion-path architecture. By simply adjusting the diffusion path length within the hydrogel, we achieved a significant change in swelling kinetics. This approach enables precise control over the diffusion and transport processes within the hydrogel, resulting in enhanced swelling kinetics when reducing the diffusion path length. Furthermore, by strategically designing the diffusion-path architecture of a 3D-printed hydrogel specimen, we can fabricate smart hydrogel actuators that exhibit reversible shape transformations during swelling and deswelling through a nonequilibrium differential swelling. The proposed approach eliminates the need to modify the spatial properties of hydrogel structures such as cross-linking density, polymer, or additive compositions, thereby achieving uniform properties throughout the hydrogel and creating new possibilities for the development of advanced 4D-printed biomedical devices

    4D-Printed Hydrogel Actuators through Diffusion-Path Architecture Design

    No full text
    Recently, smart hydrogels have garnered considerable attention as biomedical devices, and several approaches have been introduced for their fabrication, including the incorporation of stimulus-responsive additives, utilization of molecular imprinting techniques, and application of multilayered hydrogels. However, the nonuniform properties resulting from these approaches limit the practical applications of hydrogels by causing inconsistent performance and behavior. In this study, we propose a novel approach to manipulating the swelling kinetics of hydrogels by engineering their diffusion-path architecture. By simply adjusting the diffusion path length within the hydrogel, we achieved a significant change in swelling kinetics. This approach enables precise control over the diffusion and transport processes within the hydrogel, resulting in enhanced swelling kinetics when reducing the diffusion path length. Furthermore, by strategically designing the diffusion-path architecture of a 3D-printed hydrogel specimen, we can fabricate smart hydrogel actuators that exhibit reversible shape transformations during swelling and deswelling through a nonequilibrium differential swelling. The proposed approach eliminates the need to modify the spatial properties of hydrogel structures such as cross-linking density, polymer, or additive compositions, thereby achieving uniform properties throughout the hydrogel and creating new possibilities for the development of advanced 4D-printed biomedical devices

    Effects of Organic Fertilizer Substitution and Reduction on Soil Physical/Chemical Properties and Banana Growth in Banana Orchard

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    【Objective】Excessive use of fertilizers, low utilization rates of crop straw/livestock/poultry manure resources, and environmental pollution caused by agricultural and forestry waste restrict the development of agriculture. The scientific fertilization method of organic substitution+reduced fertilization was studied to provide technical support for the reduction of chemical fertilizer and soil fertility in banana production areas of the the Pearl River Delta.【Method】Field experiments were conducted to study the effects of organic substitution combined with reduced fertilization on banana growth, yield, quality and soil nutrients. The main purpose was to taking conventional fertilization as the control, four fertilizer managements were set up, including 10% reduction of fertilizer amount (10% reduction of nitrogen)+organic fertilizer (T1), 20% reduction of fertilizer amount (20% reduction of nitrogen)+organic fertilizer (T2), 10% reduction of fertilizer amount (10% reduction of nitrogen)+biochar-based-organic fertilizer (T3), and 20% reduction of fertilizer amount (20% reduction of nitrogen)+biochar-based-organic fertilizer (T4), then their effects on the banana growth, yield, and soil nutrients and physical and chemical properties were investigated.【Result】Compared with the control, Organic fertilizer substitution and reduction treatments (T1-T4) could increase the pH and organic matter content of the treated soil. Among them, pH had a more significant effect in ripening stage, increasing by 0.38-0.77. While the soil organic matter content increased more significantly in budding stage, increasing by 6.62%-56.09% compared to the control. Moreover, the soil organic matter content of soil increased with the increasing of organic material application amount. The content of large elements, Calcium and Magnesium in the treated soil during the ripening stage was generally higher than that during the budding stage, but the difference between treatments was not significant. T1-T4 treatment had positive effects on banana growth, yield, quality and leaf nutrient elements, among which the effect of T3 and T4 treatment with carbon-based organic fertilizer was better, and banana yield increased by 14.44% and 13.43% respectively. Soluble solid, soluble sugar, vitamin C content increased 13.09%-21.99%, 3.98%-17.32%, 28.09%-41.57%, respectively.【Conclusion】Comprehensive analysis of banana growth and soil physical/chemical properties, the organic fertilizer substitution combined with reduced fertilization treatment is suitable for the fertilizer reduction and efficient utilization of newly-planted bananas in the pearl river delta

    Cerebellar transcranial magnetic stimulation for improving balance capacity and activity of daily living in stroke patients: a systematic review and meta-analysis

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    Abstract Background The application of cerebellar transcranial magnetic stimulation (TMS) in stroke patients has received increasing attention due to its neuromodulation mechanisms. However, studies on the effect and safety of cerebellar TMS to improve balance capacity and activity of daily living (ADL) for stroke patients are limited. This systematic review and meta-analysis aimed to investigate the effect and safety of cerebellar TMS on balance capacity and ADL in stroke patients. Method A systematic search of seven electronic databases (PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure, Wanfang and Chinese Scientific Journal) were conducted from their inception to October 20, 2023. The randomized controlled trials (RCTs) of cerebellar TMS on balance capacity and/or ADL in stroke patients were enrolled. The quality of included studies were assessed by Physiotherapy Evidence Database (PEDro) scale. Results A total of 13 studies involving 542 participants were eligible. The pooled results from 8 studies with 357 participants showed that cerebellar TMS could significantly improve the post-intervention Berg balance scale (BBS) score (MD = 4.24, 95%CI = 2.19 to 6.29, P < 0.00001; heterogeneity, I 2  = 74%, P = 0.0003). The pooled results from 4 studies with 173 participants showed that cerebellar TMS could significantly improve the post-intervention Time Up and Go (TUG) (MD=-1.51, 95%CI=-2.8 to -0.22, P = 0.02; heterogeneity, I 2  = 0%, P = 0.41). The pooled results from 6 studies with 280 participants showed that cerebellar TMS could significantly improve the post-intervention ADL (MD = 7.75, 95%CI = 4.33 to 11.17, P < 0.00001; heterogeneity, I 2  = 56%, P = 0.04). The subgroup analysis showed that cerebellar TMS could improve BBS post-intervention and ADL post-intervention for both subacute and chronic stage stroke patients. Cerebellar high frequency TMS could improve BBS post-intervention and ADL post-intervention. Cerebellar TMS could still improve BBS post-intervention and ADL post-intervention despite of different cerebellar TMS sessions (less and more than 10 TMS sessions), different total cerebellar TMS pulse per week (less and more than 4500 pulse/week), and different cerebellar TMS modes (repetitive TMS and Theta Burst Stimulation). None of the studies reported severe adverse events except mild side effects in three studies. Conclusions Cerebellar TMS is an effective and safe technique for improving balance capacity and ADL in stroke patients. Further larger-sample, higher-quality, and longer follow-up RCTs are needed to explore the more reliable evidence of cerebellar TMS in the balance capacity and ADL, and clarify potential mechanisms

    Establishment of DNA Molecular Fingerprint of <i>Caladium</i> Core Collections

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    Caladiums are promising colorful foliage plants due to their unique leaf shapes and dazzling colors. Until now, over 2000 varieties of Caladium have been cultivated worldwide. The long-term natural variation and artificial selection have enriched the germplasm resources of Caladium in the market, yet have blurred its genetic background. In this study, 16 informative EST-SSR markers were used to screen 144 Caladium accessions, indicating that 16 EST-SSRs could distinguish all genotypes with a minimum cumulative identity probability (PI) of 2.0 2 × 10−15. Using the simulated annealing method, the richest genetic information was acquired at the same compression ratio. A final core of 44 accessions was selected, comprising 30.6% of the individuals and retraining more than 95% of the total genetic information. No significant differences were observed in allele frequency distributions or genetic diversity parameters between the core collection and the entire population. Cluster analysis roughly divided the core collections into four populations, where 66.7% of the private alleles were detected in Pop2. Finally, DNA molecular fingerprints of 44 core accessions were established, including barcodes and quick response (QR) code molecular identities (ID). The results will lay a theoretical foundation for identifying, preserving, and utilizing Caladium germplasm resources

    Enhancing hydrogel toughness by uniform cross-linking using modified polyhedral oligomeric silsesquioxane

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    Abstract The use of macro cross-linkers is one of the most effective approaches for developing tough hydrogels. However, the presence of uneven cross-linking and the resulting hydrogel inhomogeneity restrict further improvement. Here, we achieve uniform cross-linking by employing polyhedral oligomeric silsesquioxane (POSS)-grafted acrylated polyethylene glycol (PEG) as a cross-linker to enhance the toughness of hydrogels. The nano-sized hard silica core of POSS facilitates energy dissipation, and its dissolved form ensures uniform cross-linking through molecular-level dispersion. The peripheral acrylate groups introduce multiple interacting points, and the physical entanglements of long-chain PEG contribute to enhanced toughness. Incorporating acrylated POSS-PEG into polyacrylamide hydrogel yields enhanced properties such as toughness of up to 6531 kJ m−3 and break elongation up to 9455%, where the length of PEG chains grafted onto POSS is demonstrated to play a crucial role in facilitating energy dissipation and achieving high toughness
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