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Pretreatment processes are essential for the preparation of biofuels from lignocellulosic feedstocks. Based on alkaline H2O2 pretreatment, photocatalytic alkaline H2O2 pretreatment (U-AHP) was investigated to examine the effects of reaction time, alkali concentration, and H2O2 concentration on the enzymatic digestion of corn stover. The optimum process conditions were determined by orthogonal tests: 1% NaOH, 2% H2O2, and reaction time of 8 h. Under these conditions, the lignin removal efficiency of UH-AHP was 90.2% and the saccharification yield was 94.7%. Furthermore, FT-IR, XRD, and SEM analyses showed that U-AHP pretreatment caused structural damage to the maize straw and increased the crystallinity of the cellulose, and it was speculated that the U-AHP pretreatment reaction was a complex mechanism, which might be a multiple synergistic reaction. This study shows that U-AHP pretreatment is a simple, green and effective method to promote lignin removal.

Metal–organic frameworks (MOFs) with metal nodes and organic linkers have significant potential as reaction catalysts. However, one major factor impeding the development and use of MOFs as organic reaction catalysts is the detailed under-standing of catalytically active sites and their molecular reaction mechanism and selectivity. Experimentally, sulfated and Brønsted acidic MOF-808 catalyzes isobutylene dimerization. Here we report a density functional theory (DFT) based mul-ti-chemical model (cluster and periodic) transition-state study that reveals the likely active catalytic sites/species and the resulting reaction mechanism and selectivity for isobutylene dimerization catalyzed by sulfated MOF-808. Surprisingly, while there are dozens of acidic sites within a single MOF crystal, catalysis is likely the result of only a few specific active sites. Of the two-dozen acidic sites we extensively examined, only one aqua group from the tri-sulfated MOF-808 Zr6 node exhibits strong enough acidity to produce a dimerization barrier consistent with the experiment. Reaction coordinate and transition state models indicate a novel concerted dimerization process that couples C–C bond formation, C–H bond cleav-age, and proton shuttling. The selectivity between terminal and internal alkene dimerization products is likely kinetically controlled with negligible influence from the steric effects of the MOF framework.

We consider a second order boundary value problem with a parameter. A new upper bound for positive solutions and Green’s function of the problem is obtained.

The goal of this article is to analyze the problem of low computational efficiency and propagation error rate in entity recognition and relation extraction. This paper proposes a personalized education resource recommendation algorithm framework XMAMBLSTM based on deep learning in an intelligent education robot environment. XMAMBLSTM uses XLNet to assign word vectors to text sequences, employs a Multi-Bi-LSTM layer to represent complex information of word vectors, and combines a multi-headed attention layer to realize weight distribution of each word vector. The experimental results show that compared with the traditional collaborative filtering algorithm, the comprehensive evaluation indexes of the proposed method, based on the intelligent education robot environment on the two platforms, are higher than 5.05% and 17.3%, respectively.

When exposed to different relative humidities (RHs), the optical properties of atmospheric aerosols will change because of changes in the aerosol particle size and complex refractive index (RI), which will affect haze formation and global climate change. The potential contributions of ultrafine particles to the atmospheric optical characteristics and to haze spreading cannot be ignored because of their high particle number concentrations and strong diffusibility; measurement of the optical properties of wet ultrafine particles is thus highly important for environmental assessment. Therefore, a surface plasmon resonance microscopy with azimuthal rotation illumination (SPRM-ARI) system is designed to determine the RIs of single particle aerosols with diameters of less than 100 nm in the hygroscopic growth process. Measurements are taken using mixed single particles with different mass ratios. The RIs of mixed single aerosols at different RHs are retrieved by measuring the scattering light intensity using the SPRM-ARI system and almost all the RIs of the bicomponent particles with different mass ratios decrease with increasing water content under high RH conditions. Finally, for each of the bicomponent particles, the maximum standard deviations for the retrieved RI values are only 2.06×10

Xiaolong Zhang,1,&ast; Zhiyin Lei,2,&ast; Ying Wu,3 Yuanyuan Song,4 Xiaoling Wu,3,5 Bo Yang,2 Jianmei Fan,2 Shixu Feng,2 Liping Wu,2 Lingyan Li,2 Qin Dai,2 Zhen Zeng,2 Mei Feng,3 Tingting Zhang3 1Department of Thoracic Surgery, West China Hospital, Sichuan University, Chengdu, Sichuan Province, People’s Republic of China; 2Department of Respiratory and Critical Care Medicine, Jiajia Central Health Center of Chengdu Eastern New Area, Chengdu Eastern New Area, Sichuan Province, People’s Republic of China; 3Department of Respiratory and Critical Care Medicine, West China Hospital, Sichuan University/West China School of Nursing, Sichuan University, Chengdu, Sichuan Province, People’s Republic of China; 4Department of Critical Care Medicine, West China Hospital, Sichuan University, Chengdu, Sichuan Province, People’s Republic of China; 5Department of Nursing, Sanya People’s Hospital/West China (Sanya) Hospital, Sichuan University, Sanya, Hainan Province, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Ying Wu, Department of Respiratory and Critical Care Medicine, West China Hospital, Sichuan University/West China School of Nursing, Sichuan University, No. 37 Guoxue Alley, Chengdu, Sichuan Province, 610041, People’s Republic of China, Tel +86-18980606932, Email 358383278@qq.comPurpose: To investigate the prevalence and risk factors for chronic obstructive pulmonary disease (COPD) in a rural area in western China with severe air pollution.Patients and Methods: 10% of local residents aged 40 years and above were included using a convenience sampling method. This was a cross-sectional study. A self-designed questionnaire was used to collect participants’ demographic data. The screening program was comprised of two steps: First, a portable electronic spirometer was used for COPD screening. Those participants with FEV1/FVC ratio < 0.7 were then referred to a confirmatory pulmonary function (PF) test. COPD was confirmed according to the 2020 Global Initiative for Chronic Obstructive Lung Disease criteria.Results: A total of 4577 participants aged 40 years old or above were included in the final analysis. Examination with a mobile spirometer identified 1159 individuals for confirmatory testing; after that, of the 1159 individuals, 889 were diagnosed with COPD by the confirmatory PF test. The prevalence of COPD among the target group was 19.4%. Older age, male sex (odds ratio [OR] = 1.537, 95% confidence interval [CI] 1.246– 1.894), smoking history (OR = 1.338, 95% CI 1.069– 1.675), family history of respiratory disease (OR = 1.625, 95% CI 1.350– 1.957), education level (OR = 0.735, 95% CI 0.617– 0.876), overweight (OR = 0.614, 95% CI 0.517– 0.730) and obesity (OR = 0.572, 95% CI 0.449– 0.721) were identified as independent factors associated with COPD. The screening program helped earlier detection of COPD in 719 participants.Conclusion: COPD was highly prevalent in the rural area studied. Rural residents who were older, current or ever-smokers, male and those who had a lower education level were more vulnerable to developing COPD. The COPD screening program may be helpful for earlier disease detection in rural health-care settings.Keywords: chronic obstructive pulmonary disease, prevalence, primary care, pulmonary function test, risk factors