Microwave-Assisted Oxalic Acid Pretreatment for the Enhancing of Enzyme Hydrolysis in the Production of Xylose and Arabinose from Bagasse.

In this study, highly-efficient hydrolysis of bagasse into xylose and arabinose sugars (C5 sugars) was developed by microwave-assisted oxalic acid pretreatment under mild reaction conditions. The effects of acid and hydrolysis conditions on the C5 sugar yields were discussed. The results showed that oxalic acid performed better than hydrochloric acid and maleic acid, and was a promising alternative to sulfuric acid for xylose production at the same acid concentration. The maximum yields of xylose (95.7%) and arabinose (91.5%) were achieved via the microwave-assisted oxalic acid pretreatment (120 °C, 10 min, 0.4 mol/L, solid-liquid ratio of 1:50 g/mL), indicating that almost all xylan-type hemicelluloses were released from the cell wall and hydrolyzed into C5 sugars. After pretreatment, more than 90% of the cellulose in the residual bagasse was converted to glucose (92.2%) by enzymatic hydrolysis. This approach could realize the highly-efficient hydrolysis of xylan from bagasse into C5 sugars, which would enhance the enzyme hydrolysis of treated bagasse into glucose.

The inoculum dose of Zika virus can affect the viral replication dynamics, cytokine responses and survival rate in immunocompromised AG129 mice.

Zika virus, a mosquito-borne arbovirus, has repeatedly caused large pandemics with symptoms worsening from mild and self-limiting diseases to Guillain-Barré syndrome in adults and fetal microcephaly in newborns. In recent years, Zika virus diseases have posed a serious threat to human health. The shortage of susceptible small animal models makes it difficult to study pathogenic mechanisms and evaluate potential therapies for Zika virus infection. Therefore, we chose immunocompromised mice (AG129 mice) deficient in IFN-α/ß and IFN-γ receptors, which can abolish the innate immune system that prevents Zika virus infection early. AG129 mice were infected with the Zika virus, and this mouse model exhibited replication dynamics, tissue tropism, pathological lesion and immune activation of the Zika virus. Our results suggest that the inoculum dose of Zika virus can affect the viral replication dynamics, cytokine responses and survival rate in AG129 mice. By testing the potential antiviral drug favipiravir, several critical indicators, including replication dynamics and survival rates, were identified in AG129 mice after Zika virus infection. It is suggested that the model is reliable for drug evaluation. In brief, this model provides a potential platform for studies of the infectivity, virulence, and pathogenesis of the Zika virus. Moreover, the development of an accessible mouse model of Zika virus infection will expedite the research and deployment of therapeutics and vaccines.

Scale-invariant Mexican Hat wavelet descriptor for non-rigid shape similarity measurement.

The Mexican Hat wavelet (MHW) is strictly derived from the heat kernel by taking its negative first-order derivative with respect to time t. As a solution to the heat equation that the heat kernel has a clear initial condition, the Laplace-Beltrami operator. Although the MHW descriptor can effectively characterize the model information, but it has poor robustness to the model with scale transformation, and the feature description performance is affected to some extent. Following a popular mathematical method, in this paper, we bases on the MHW to study scaling invariance and proposes a new shape descriptor, the scale-invariant Mexican Hat wavelet (SIMHW), which by logarithmic sampling and Fourier transform that obtains the expression of SIMHW in Fourier domain. The experimental results show that SIMHW has finer information description ability and stronger recognition ability, and has better robustness to various non-rigid transformations. It can correctly calculate the similarity between 3D shapes and realize the effective shape retrieval.

Hemicellulose from Plant Biomass in Medical and Pharmaceutical Application: A Critical Review.

BACKGROUND: Due to the non-toxicity, abundance and biodegradability, recently more and more attention has been focused on the exploration of hemicellulose as the potential substrate for the production of liquid fuels and other value-added chemicals and materials in different fields. This review aims to summarize the current knowledge on the promising application of nature hemicellulose and its derivative products including its degradation products, its new derivatives and hemicellulosebased medical biodegradable materials in the medical and pharmaceutical field, especially for inmmune regulation, bacteria inhibition, drug release, anti-caries, scaffold materials and anti-tumor. METHODS: We searched the related papers about the medical and pharmaceutical application of hemicellulose and its derivative products, and summarized their preparation methods, properties and use effects. RESULTS: Two hundred and twenty-seven papers were included in this review. Forty-seven papers introduced the extraction and application in immune regulation of nature hemicellulose, such as xylan, mannan, xyloglucan (XG) and ß-glucan. Seventy-seven papers mentioned the preparation and application of degradation products of hemicellulose for adjusting intestinal function, maintaining blood glucose levels, enhancing the immunity and alleviating human fatigue fields such as xylooligosaccharides, xylitol, xylose, arabinose, etc. The preparation of hemicellulose derivatives were described in thirty-two papers such as hemicellulose esters, hemicellulose ethers and their effects on anticoagulants, adsorption of creatinine, the addition of immune cells and the inhibition of harmful bacteria. Finally, the preparations of hemicellulose-based materials such as hydrogels and membrane for the field of drug release, cell immobilization, cancer therapy and wound dressings were presented using fifty-five papers. CONCLUSION: The structure of hemicellulose-based products has the significant impact on properties and the use effect for the immunity, and treating various diseases of human. However, some efforts should be made to explore and improve the properties of hemicellulose-based products and design the new materials to broaden hemicellulose applications.

A feasible process for furfural production from the pre-hydrolysis liquor of corncob via biochar catalysts in a new biphasic system.

A feasible approach was developed to produce furfural from the pre-hydrolysis liquor of corncob via biochar catalysts as the solid acid catalyst in a new biphasic system with dichloromethane (DCM) as the organic phase and the concentrated pre-hydrolysis liquor (CPHL) containing NaCl as the aqueous phase. The biochar catalyst possessing many acidity groups (SO3H, COOH and phenolic OH groups) was prepared by the carbonization and sulfonation process of the corncob hydrolyzed residue. The influence of the catalytic condition on furfural yield and selectivity was comparatively studied. It was found that 81.14% furfural yield and 83.0% furfural selectivity were obtained from CPHL containing 5wt% xylose using this biochar catalyst in the CPHL-NaCl/DCM biphasic system at 170°C for 60min. In addition, with the regeneration process, this catalyst displayed the high performance and excellent recyclability.