321 research outputs found
Supplementary Figure -Supplemental material for MiR-7 inhibited peripheral nerve injury repair by affecting neural stem cells migration and proliferation through cdc42
No full textSupplemental material, Supplementary Figure for MiR-7 inhibited peripheral nerve injury repair by affecting neural stem cells migration and proliferation through cdc42 by Nan Zhou, Shuang Hao, Zongqiang Huang, Weiwei Wang, Penghui Yan, Wei Zhou, Qihang Zhu and Xiaokang Liu in Molecular Pain</p
sj-pdf-1-ccx-10.1177_10732748211051554 – Supplemental Material for The Identification of Prognostic and Metastatic Alternative Splicing in Skin Cutaneous Melanoma
No full textSupplemental Material, sj-pdf-1-ccx-10.1177_10732748211051554 for The Identification of Prognostic and Metastatic Alternative Splicing in Skin Cutaneous Melanoma by Runzhi Huang, Mingxiao Li, Zhiwei Zeng, Jie Zhang, Dianwen Song. Peng Hu, Penghui Yan, Shuyuan Xian, Xiaolong Zhu, Zhengyan Chang, Jiayao Zhang, Juanru Guo, Huabin Yin, Tong Meng and Zongqiang Huang in Cancer Control</p
Power spectral density analysis for nonlinear systems based on Volterra series
No full textA consequence of nonlinearities is a multi-harmonic response via a mono-harmonic excitation. A similar phenomenon also exists in random vibration. The power spectral density (PSD) analysis of random vibration for nonlinear systems is studied in this paper. The analytical formulation of output PSD subject to the zero-mean Gaussian random load is deduced by using the Volterra series expansion and the conception of generalized frequency response function (GFRF). For a class of nonlinear systems, the growing exponential method is used to determine the first 3rd-order GFRFs. The proposed approach is used to achieve the nonlinear system's output PSD under a narrow-band stationary random input. The relationship between the peak of PSD and the parameters of the nonlinear system is discussed. By using the proposed method, the nonlinear characteristics of multi-band output via single-band input can be well predicted. The results reveal that changing nonlinear system parameters gives a one-of-a-kind change of the system's output PSD. This paper provides a method for the research of random vibration prediction and control in real-world nonlinear systems
Rapid room-temperature synthesis of biocompatible metal-organic framework for enzyme immobilization with improved stability and on-demand release
No full textEnzyme immobilization within metal–organic frameworks (MOFs) addresses the inherent fragility of enzymes, playing a crucial role across diverse industries by improving efficiency and lowering economic costs. While the application of MOFs in the food and pharmaceutical industries is constrained by toxicity concerns, MIL-88A(Fe) emerges as an ideal candidate due to its non-toxicity and biocompatibility. However, the release of encapsulated enzymes is significantly hampered, reducing their bioactivity. Herein, we present a safe and simple platform for creating enzyme@MIL-88A, which provides enzyme stabilization and controlled release. The thermal stabilization of a spectrum of enzymes (phytase, xylanase, amylase, mannanase, and glucanase) is achieved, elevating their endurance threshold to 95 ◦C. Furthermore, the controlled on-demand release of the encapsulated enzymes at target sites is accomplished by adjusting defects in enzyme@MIL-88A composites via an acid modulation approach, while preserving enzyme activity. This approach has improved the amount of enzyme released from 10 % to 99.7 %. To the best of our knowledge, this is the first time enzyme@MIL-88A has been synthesized rapidly under mild conditions for enzyme stabilization and controlled release. Our method offers a universal platform for stabilizing vulnerable biomaterials and the controlled delivery of biological macromolecules.Yilun Weng, Penghui Yan, Baode Sun, Andria Wan, Jiakang You, Xin Xu, Zeyu Lu, Glen A. Stewart, Xiaojing Chen, Hao Song, Chun-Xia Zha
Policy narratives about the European Green Deal: Computational text analysis of policy narratives on the transition from internal combustion vehicles to new energy vehicles
No full textComplex Systems Engineering and Management (CoSEM
Enzyme encapsulation in metal-organic frameworks using spray drying for enhanced stability and controlled release: A case study of phytase
No full textEncapsulating enzymes in metal-organic frameworks is a common practice to improve enzyme stability against harsh conditions. However, the synthesis of enzyme@MOFs has been primarily limited to small-scale laboratory settings, hampering their industrial applications. Spray drying is a scalable and cost-effective technology, which has been frequently used in industry for large-scale productions. Despite these advantages, its potential for encapsulating enzymes in MOFs remains largely unexplored, due to challenges such as nozzle clogging from MOF particle formation, utilization of toxic organic solvents, controlled release of encapsulated enzymes, and high temperatures that could compromise enzyme activity. Herein, we present a novel approach for preparing phytase@MIL-88 A using solvent-free spray drying. This involves atomizing two MOF precursor solutions separately using a three-fluid nozzle, with enzyme release controlled by manipulating defects within the MOFs. The physicochemical properties of the spray dried particles are characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy. Leveraging the efficiency and scalability of spray drying in industrial production, this scalable encapsulation technique holds considerable promise for broad industrial applications.Yilun Weng, Xin Xu, Penghui Yan, Jiakang You, Xiaojing Chen, Hao Song, Chun-Xia Zha
Mechanistic study on phytase stabilization using alginate encapsulation
No full textEnzyme encapsulation has emerged as a promising strategy for protecting enzymes against denaturation under harsh conditions. Alginate encapsulation using a dripping and gelation method is a common technique for encapsulating enzymes, however, the encapsulation efficiency is often limited due to the quick diffusion of water-soluble enzymes into the gelation bath. Herein, we report a novel post-loading enzyme encapsulation method with a 100% encapsulation efficiency and a high enzyme loading. We demonstrate a 20-fold enzyme thermal stability improvement upon encapsulation. Furthermore, we investigate the effects of alginate pore size, enzyme concentration, and enzyme distribution on the thermal stability of encapsulated enzyme using both experimental and computational methods, elucidating the mechanism underlying the stability improvement of the encapsulated enzyme. Additionally, the encapsulated enzyme demonstrates successful release under simulated gastric conditions. This highly efficient enzyme encapsulation system, utilizing food-grade encapsulation materials and an environmentally friendly synthesis approach, holds great promise for various applications in the food industry.Yilun Weng, Baode Sun, Wanli Jin, Penghui Yan, Xiaojing Chen, Hao Song, Chun- Xia Zha
Hydrodeoxygenation of biocrude oil to value-added products
No full textThe utilisation of biomass has drawn widespread attention due to the fast depletion of fossil energy resources and environmental challenges. Biocrude oil, derived from pyrolysis or liquefaction of lignocellulosic biomass, contains a high level of oxygen leading to some detrimental properties (high viscosity, high corrosivity, low heating value and low thermal stability). Therefore, hydrodeoxygenation of the biocrude is necessary to remove the oxygen atoms and produce value-added fuels and chemicals. Hydrodeoxygenation (HDO) is a two-step process which involves the hydrogenation and deoxygenation. The hydrogenation commonly occurs in the presence of metal sites, and the acid sites play a crucial role in the deoxygenation. Therefore, the HDO catalysts are routinely composed of metals (such as Pt, Pd, Ru, and Ni) and supports (ZrO₂, Al₂O₃ and zeolites). Due to the complexity of biocrude oil, a model compound (guaiacol), which possesses two different oxygen-containing groups, was employed in this study. In the first step, the Ru/BEA and Ru/ZSM-5 with varied Si/Al ratios were studied to examine the influence of supports with varying acidity and pore size on HDO of biocrude oil and guaiacol in a batch-type reactor operated at 4.0 MPa hydrogen. It was observed that a decrease in the Si/Al ratio of the support generated an increase in the yield of cyclohexane and a decrease in the yield of 2-methoxycyclohexanol in HDO of guaiacol. Both Ru/BEA and Ru/ZSM-5, possessing low Si/Al ratios, displayed a high activity for HDO for guaiacol while only Ru/BEA catalyst exhibits a high activity for HDO of biocrude oil. Catalyst characterisation shows that the Ru/BEA catalyst, with a low Si/Al ratio, not only possesses strong B acid sites but also contains extensive mesoporosity. Notably, these mesopores appear to facilitate the hydrogenation, deoxygenation, and ring-opening of large oxygenated and condensed-ring hydrocarbons in biocrude oil which then leads to a high yield of cycloalkanes. As expected, the Ru/Al₂O₃ and Ru/SiO₂ catalysts exhibit a high hydrogenation activity but a low deoxygenation activity in the HDO of guaiacol and biocrude oil due to the absence of B acid sites. These results suggest that the larger pore support, with strong B acid sites, engendered the observed HDO activity. The reaction pathway for the main components of biocrude oil was proposed based on the observed reaction product distribution. Although Ru-based catalysts display a high HDO activity, the high cost could hinder their wide application in industry. Therefore, metallic Ni, which is low cost, non-sulfided, and has the advantage of high hydrogenation activity was employed as the main metal phase in this project. The influence of catalyst pore size and shape selectivity on the catalytic hydrodeoxygenation (HDO) of biocrude oil has been investigated by comparing the activity of nickel catalysts on the supports of different pore sizes towards model compounds of increasing dimension. Five model compounds (guaiacol, anisole, phenanthrene, pyrene, and 1,3,5-trimethoxybenzene), and five zeolite supports (small-pore ZSM-5, medium-pore MOR, large-pore Beta and Y, and mesoporous Al-MCM-41) have been investigated. Hydrodeoxygenation and hydrogenation activities were determined on the basis of the yield of the associated cycloalkanes. All catalysts show a high HDO activity for small molecules (anisole and guaiacol) while the catalysts with medium and large pore supports display high HDO activity for 1,3,5-trimethoxybenzene. Furthermore, the large pore catalysts (Ni/Y and Ni/Beta) exhibit high hydrogenation activity for phenanthrene, while only the extra-large pore size catalyst (Ni/Y) presents good hydrogenation and HDO activities for all model compounds. The mesoporous Ni/Al-MCM-41 catalyst shows low HDO and hydrogenation activities for large model compounds, which can be ascribed to its low metal dispersion and low concentration of acid sites. In addition, the Ni/Beta and Ni/ZSM-5 were also tested in HDO of biocrude oil. Ni/Beta catalyst displays a higher yield of cycloalkanes than that of Ni/ZSM-5, which confirms that the selection of catalyst support can have impact on the product distribution in HDO of biocrude.
The BEA supported Ni catalyst, which possesses high concentration of acid sites and mesopores, displays a high HDO activity for guaiacol and biocrude oil, however, results from batch reactor cannot provide the information about turnover frequency of active sites. Therefore BEA zeolite, with different Si/Al ratios (12.5, 25, 175) and varying metal loadings (2.3 ~23.4 wt%), was studied in a flow reactor to examine the influence of catalyst acidity and the structure of Ni on the performance, with particular emphasis on the change in product selectivity. The ratio of cyclohexane formation rate to the concentration of acid sites in reduced catalysts was found to be roughly constant when HDO of guaiacol in a flow reactor over 15.7 wt% Ni/BEA catalysts with different acid site concentrations, demonstrating the deoxygenation activity increases with increasing number of acid sites. On the other hand, the materials with the majority of isolated Ni sites (prepared by ion exchange) showed no cyclohexane yield at 230 degree. However, at higher temperatures, the formation of cyclohexane was observed, as a result of a consecutive reaction where catechol was generated by acid sites and subsequently reduced to cyclohexane on isolated Ni sites. With respect to catalysts with higher Ni-loading, the selectivity towards cyclohexane increases with an increased Ni loading up to 15.7 wt%. This is attributed to the formation of larger Ni nanoparticles upon H₂ reduction. A higher concentration of nickel hydrides compared to isolated Ni sites was observed by H₂-TPD and H₂-FTIR. The nickel hydrides are believed to be crucial intermediates in the hydrogenation reaction. Based on the product distribution over catalysts containing mainly isolated Ni sites and the Ni nanoparticles, two different reaction pathways were proposed. Traditionally, catalysts with high metal loadings are indispensable for improved catalytic performance. Supported metal catalysts are typically prepared by incipient wetness impregnation, which inevitably gives rise to inhomogeneous metal distribution and leads to large metal particles formed via agglomeration. Therefore, highly dispersed Ni/BEA catalysts prepared via ion-exchange-deposition-precipitation (IDP) utilising careful pH control were conducted. In comparison, catalysts prepared by incipient wetness impregnation (IWI) and deposition-precipitation (DP) methods were also investigated and IDP catalysts were shown to have higher dispersion. A significantly increased selectivity toward hydrocarbons was observed over these carefully prepared catalysts. The presence of nickel hydrides was confirmed by H₂-TPD and H₂-FTIR. IDP catalyst exhibits a higher metal dispersion and higher concentration of nickel hydrides than impregnated and DP catalysts, while larger Ni nanoparticles formed in impregnated catalysts show a higher concentration of nickel hydrides per surface Ni. The guaiacol conversion was not significantly affected by the catalyst preparation method, while the product selectivity was altered. Higher cyclohexane formation rate was detected over IDP catalysts compared to DP and impregnated catalysts. Besides, cyclohexane formation rate presents a positive linear correlation with the concentration of nickel hydrides, suggesting nickel hydrides play a crucial role in the hydrodeoxygenation reaction. The factors affecting catalyst deactivation during HDO in a continuous-flow reactor were investigated in order to gain insight into the deactivation mechanism of BEA-supported Ni catalyst. Phenolic-OH group moieties accelerate catalyst deactivation through the production of condensed-ring compounds, which then leads to the blockage of pores. In contrast, the yield of cycloalkane did not change with time-on-stream when using toluene, cyclohexanol and anisole as feeds, suggesting aromatic-ring, alkyl-OH and aromatic-OCH₃ have negligible effect on catalyst deactivation. Operation at low weight hour space velocity (WHSV) values increase the yield of cycloalkane and reduce the rate of catalyst deactivation. High metal loadings can increase selectivity to cyclohexane, however, the production of condensed-ring products is also enhanced, which is likely to be the result of an increased concentration of surface cyclohexane carbocations. Furthermore, high metal loadings play a limited role in preventing the catalyst from deactivation. In addition, the activity and stability of catalysts were positively affected by an increase in reaction temperature (up to 230°C). Based on the product distribution observed, a coupling reaction pathway (leading to the formation of condensed-ring products and cycloalkanes) is proposed
- …
