Search

Abstract 2,6-Di-tert-butyl-4-methylphenol (BHT) is an excellent antioxidant that is easily oxidized to 2,6-di-tert-butyl-4-hydroperoxyl-4-methyl-2,5-cyclohexadienone (BHTOOH). For the safety of BHT production and usage, it is meaningful to study the thermal stability and decomposition properties of BHT and BHTOOH. In this paper, the thermal decomposition properties of BHT and BHTOOH were compared by the mini closed pressure vessel test (MCPVT) and differential scanning calorimetry (DSC). Their kinetics of thermal decomposition were studied using thermogravimetric analysis (TGA). The thermal decomposition products of BHT and BHTOOH were analyzed by gas chromatography-mass spectrometry (GC–MS). The results show that there was no significant change in temperature pressure when BHT was warmed up under a nitrogen atmosphere, indicating that BHT was stable within 400 K. The thermal decomposition reaction of BHTOOH was rapid with an initial reaction temperature of 375.2 K. The initial exothermic temperature (Ti) and heat release (QDSC) of DSC were 384.9 K and 865.0 J g−1, respectively. The apparent activation energies (Ea) for the thermal decomposition reactions of BHT and BHTOOH calculated by the Kissinger method were 151.8 kJ mol−1 and 66.07 kJ mol−1, respectively. The main decomposition products of BHT were isobutene and 2-tert-butyl-4-methylphenol. The thermal decomposition products of BHTOOH included BHT, 2,6-di-tert-butyl-4-ethylphenol, 3,5-di-tert-butyl-4-hydroxybenzaldehyde, 4,4′-(1,2-ethanediyl) bis [2,6-bis (1,1-dimethylethyl) phenol, etc. Based on the thermal decomposition behavior and products, the reaction pathway has been described. These results indicate that BHT is a potential thermal hazard during production, storage and application. For the safety of the chemical industry, the oxidation of BHT should be avoided.

Abstract In this study, the oxidation characteristics of isoprene were investigated using a custom-designed mini closed pressure vessel test (MCPVT). The results show that isoprene is unstable and polymerization occurs under a nitrogen atmosphere. Under an oxygen atmosphere, the oxidation process of isoprene was divided into three stages: (1) isoprene reacts with oxygen to produce peroxide; (2) Peroxides produce free radicals through thermal decomposition; (3) Free radicals cause complex oxidation and thermal runaway reactions. The oxidation of isoprene conforms to the second-order reaction kinetics, and the activation energy was 86.88 kJ·mol−1. The thermal decomposition characteristics of the total oxidation product and purified peroxide mixture were determined by differential scanning calorimetry (DSC). The initial exothermic temperatures T on were 371.17 K and 365.84 K, respectively. And the decomposition heat Q DSC were 816.66 J·g−1 and 991.08 J·g−1, respectively. It indicates that high concentration of isoprene peroxide has a high risk of thermal runaway. The results of thermal runaway experiment showed that the temperature and pressure of isoprene oxidation were prone to rise rapidly, which indicates that the oxidation reaction was dangerous. The reaction products of isoprene were analyzed by gas chromatography-mass spectrometry (GC–MS). The main oxidation products were methyl vinyl ketone, methacrolein, 3-methylfuran, etc. The main thermal runaway products were dimethoxymethane, 2,3-pentanedione, naphthalene, etc. Based on the reaction products, the possible reaction pathway of isoprene was proposed.

Traditional rock wool fibres are susceptible to crystallization and pulverization. To mitigate this, glass fibres were produced from iron ore waste (IOW). When the ratio of Fe2+ and Fe3+ is 1:3 and the Al2O3 content is 10 wt.%, increasing the FexOy content enhances the thermal stability.At an FexOy content of 17–19% and an Al2O3 content of 10–13%, the glass transition temperature (Tg) peaked. Increasing the FexOy content from 10% to 20% enhanced the stability of Si-O and Al-O bonds and increased bridged oxygen, stabilizing the structure. Here, Fe2+ balances structural charges, while Fe3+ replaces some Al atoms in the network. When the Al2O3 content is 10–13% and the FexOy content is 17–19%, the thermal stability of the IOW rock glass reaches its optimal level. At 20% FexOy content, the structure becomes three-dimensional and cyclic, increasing polymerization. Consequently, incorporating FexOy alongside a 10% Al2O3 content improves thermal stability, supporting the development of high-stability rock wool from IOW. This approach also enhances the refractory properties of rock wool fibres within the FexOy-Al2O3-SiO2-MgO-CaO system.

Motion control of robots is a high-dimensional, nonlinear control problem that is often difficult to handle using traditional dynamical path planning means. Reinforcement learning is currently an effective means to solve robot motion control problems, but reinforcement learning has disadvantages such as high number of trials and errors and sparse rewards, which restrict the application efficiency of reinforcement learning. The Hindsight Experience Replay(HER) algorithm is a reinforcement learning algorithm that solves the reward sparsity problem by constructing virtual target values. However, the HER algorithm still suffers from the problem of long time in the early stage of training, and there is still room for improving its sample utilization efficiency. Augmentation by existing data to improve training efficiency has been widely used in supervised learning, but is less applied in the field of reinforcement learning. In this paper, we propose the Hindsight Experience Replay with Transformed Data Augmentation (TDAHER) algorithm by constructing a transformed data augmentation method for reinforcement learning samples, combined with the HER algorithm. And in order to solve the problem of the accuracy of the augmented samples in the later stage of training, the decaying participation factor method is introduced. After the comparison of four simulated robot control tasks, it is proved that the algorithm can effectively improve the training efficiency of reinforcement learning.

Although pinane has a wide range of uses, there are no reports on the safety of pinane oxidation. The thermal oxidation properties of pinane were investigated through MCPVT. The primary oxidation products of pinane were separated and structurally characterised, and its decomposition properties were assessed by MCPVT and DSC. The results showed that pinane had an initial oxygen uptake temperature of 123.5 °C and exploded when the temperature rose to 132.7 °C. Pinane autoxidised at 110 °C for 9 h formed a high level of peroxide (81.18 mmol/kg) with an activation energy of 138.77 kJ/mol. The oxidation of pinane occurs mainly at the tertiary carbon atom attached to the methyl group, and the main peroxide produced is pinane hydroperoxide (PHP). PHP has an exothermic onset temperature (Tonset), a heat of decomposition (QDSC) and an activation energy of decomposition of 114.6 °C, 1878.0 J/g and 109.4 kJ/mol respectively, which should classify it as a hazardous substance. PHP has a lower activation energy than pinane and is the determining factor for the safety of the pinane oxidation reaction. The products of thermal runaway of pinane are relatively complex and consist mainly of 1-(2, 2-dimethyl-3-ethylcyclobutyl) ethanone, nopinone, 2, 3-pinanediol and pinonic acid.

α-Pinene, β-pinene and turpentine are renewable resources that are widely used in fine chemicals, fuels and other applications, and the safety of their production, transport and use should be considered. In this work, the characteristics and hazardous of the oxidation process of α-pinene, β-pinene and turpentine were investigated by using a novel mini closed pressure vessel testing system (MCPVT). The oxidation products were resolved by gas chromatography-mass spectrometry (GC–MS). The results showed that α-pinene, β-pinene and turpentine were stable under nitrogen atmosphere and very active chemically under oxygen atmosphere. The activation energies (Ea) of α-pinene, β-pinene and turpentine were calculated to be 78.87, 109.69 and 98.82 kJ/mol, respectively, using pressure–time (P-t) curves. So, the reaction activity sequence was α-pinene > turpentine > β-pinene. The peroxide concentrations of α-pinene (363 K), β-pinene (358 K) and turpentine (363 K) could reach 81.94, 84.70 and 75.76 mmol/kg, respectively, at relatively low temperatures. 0.6 g of α-pinene exploded at a system temperature of 369 K and an oxygen pressure of 1.23 MPa. 0.6 g of β-pinene also exploded at a system temperature of 373 K and an oxygen pressure of 1.27 MPa. 0.4 g of turpentine experienced thermal runaway at a system temperature of 384 K and an oxygen pressure of 0.81 MPa. The major oxidation products of α-pinene are α-campholenaldehyde, laevo-pinocarveol, verbenol, verbenone, bicyclo (3.1.1)heptane-2, 3-diol, 2, 6, 6-trimethyl, 2-cyclohexen-1-ol, 2-methyl-5-(1-methylethenyl)-, (1R,5R)-rel-, cyclobutaneacetic acid, 3-acetyl-2, 2-dimethyl, myrtenol and myrtenal. The major thermal runaway products are water, ethanol, acetone, acetic acid, 2-pentanone, propyl acetate, toluene, cymene and methylacetophenone. The major oxidation products of β-pinene are nopinone, laevo-pinocarveol, pinocarvone, myrtenol, myrtenal and perillyl alcohol. The major thermal runaway products are water, ethanol, acetone, n-ethyl propanoate, toluene, butyl acetate, cymene, apocamphor, nopinone, bornyl formate, methylacetophenone and dihydronopol. The oxidation products and thermal runaway products of pinene were significantly different. Possible reaction pathways for α-pinene and β-pinene are proposed.

Abstract Background Keratin, the main component of chicken feather, is the third most abundant material after cellulose and chitin. Keratin can be converted into high-value compounds and is considered a potential high-quality protein supplement; However, its recalcitrance makes its breakdown a challenge, and the mechanisms of action of keratinolytic proteases-mediated keratinous substrates degradation are not yet fully elucidated. Bacillus sp. CN2, having many protease-coding genes, is a dominant species in keratin-rich materials environments. To explore the degradation patterns of feather keratin, in this study, we investigated the characteristics of feather degradation by strain CN2 based on the functional-degradomics technology. Results Bacillus sp. CN2 showed strong feather keratin degradation activities, which could degrade native feathers efficiently resulting in 86.70% weight loss in 24 h, along with the production of 195.05 ± 6.65 U/mL keratinases at 48 h, and the release of 0.40 mg/mL soluble proteins at 60 h. The extracellular protease consortium had wide substrate specificity and exhibited excellent biodegradability toward soluble and insoluble proteins. Importantly, analysis of the extracellular proteome revealed the presence of a highly-efficient keratin degradation system. Firstly, T3 γ-glutamyltransferase provides a reductive force to break the dense disulfide bond structure of keratin. Then S8B serine endopeptidases first hydrolyze keratin to expose more cleavage sites. Finally, keratin is degraded into small peptides under the synergistic action of proteases such as M4, S8C, and S8A. Consistent with this, high-performance liquid chromatography (HPLC) and amino acid analysis showed that the feather keratin hydrolysate contained a large number of soluble peptides and essential amino acids. Conclusions The specific expression of γ-glutamyltransferase and co-secretion of endopeptidase and exopeptidase by the Bacillus sp. CN2 play an important role in feather keratin degradation. This insight increases our understanding of the keratinous substrate degradation and may inspire the design of the optimal enzyme cocktails for more efficient exploration of protein resources in industrial applications.

Hepatocellular carcinoma (HCC) is one of most common and deadliest malignancies. Celastrol (Cel), a natural product derived from the Tripterygium wilfordii plant, has been extensively researched for its potential effectiveness in fighting cancer. However, its clinical application has been hindered by the unclear mechanism of action. Here, we used chemical proteomics to identify the direct targets of Cel and enhanced its targetability and anti-tumor capacity by developing a Cel-based liposomes in HCC. We demonstrated that Cel selectively targets the voltage-dependent anion channel 2 (VDAC2). Cel directly binds to the cysteine residues of VDAC2, and induces cytochrome C release via dysregulating VDAC2-mediated mitochondrial permeability transition pore (mPTP) function. We further found that Cel induces ROS-mediated ferroptosis and apoptosis in HCC cells. Moreover, coencapsulation of Cel into alkyl glucoside-modified liposomes (AGCL) improved its antitumor efficacy and minimized its side effects. AGCL has been shown to effectively suppress the proliferation of tumor cells. In a xenograft nude mice experiment, AGCL significantly inhibited tumor growth and promoted apoptosis. Our findings reveal that Cel directly targets VDAC2 to induce mitochondria-dependent cell death, while the Cel liposomes enhance its targetability and reduces side effects. Overall, Cel shows promise as a therapeutic agent for HCC.

Abstract Owing to their superior capabilities and advanced achievements, Transformers have gradually attracted attention with regard to understanding complex brain processing mechanisms. This study aims to comprehensively review and discuss the applications of Transformers in brain sciences. First, we present a brief introduction of the critical architecture of Transformers. Then, we overview and analyze their most relevant applications in brain sciences, including brain disease diagnosis, brain age prediction, brain anomaly detection, semantic segmentation, multi‐modal registration, functional Magnetic Resonance Imaging (fMRI) modeling, Electroencephalogram (EEG) processing, and multi‐task collaboration. We organize the model details and open sources for reference and replication. In addition, we discuss the quantitative assessments, model complexity, and optimization of Transformers, which are topics of great concern in the field. Finally, we explore possible future challenges and opportunities, exploiting some concrete and recent cases to provoke discussion and innovation. We hope that this review will stimulate interest in further research on Transformers in the context of brain sciences.

Background and objectiveSedentary behavior is of increasing concern in older patients with type 2 diabetes mellitus (T2DM) due to its potential adverse effects on cardiovascular health, cognitive function, and motor function. While regular exercise has been shown to improve the health of individuals with T2DM, the most effective exercise program for elderly sedentary patients with T2DM remains unclear. Therefore, the objective of this study was to assess the impact of high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), and guideline-based physical activity programs on the cardiovascular health, cognitive function, and motor function of this specific population.MethodsThis study will be a randomized, assessor-blind, three-arm controlled trial. A total of 330 (1:1:1) elderly sedentary patients diagnosed with T2DM will be randomly assigned the HIIT group (10 × 1-min at 85–95% peak HR, intersperse with 1-min active recovery at 60–70% peak HR), MICT (35 min at 65–75% peak HR), and guideline-based group (guideline group) for 12 weeks training. Participants in the guideline group will receive 1-time advice and weekly remote supervision through smartphones. The primary outcomes will be the change in glycosylated hemoglobin (HbA1c) and brain-derived neurotrophic factor (BDNF) after 12-weeks. Secondary outcomes will includes physical activity levels, anthropometric parameters (weight, waist circumference, hip circumference, and body mass index), physical measurements (fat percentage, muscle percentage, and fitness rate), cardiorespiratory fitness indicators (blood pressure, heart rate, vital capacity, and maximum oxygen), biochemical markers (high-density lipoprotein, low-density lipoprotein, triglycerides, total cholesterol, and HbA1c), inflammation level (C-reactive protein), cognitive function (reaction time and dual-task gait test performance), and motor function (static balance, dynamic balance, single-task gait test performance, and grip strength) after 12 weeks.DiscussionThe objective of this study is to evaluate the effect of 12 weeks of HIIT, MICT, and a guideline-based physical activity program on elderly sedentary patients diagnosed with T2DM. Our hypothesis is that both HIIT and MICT will yield improvements in glucose control, cognitive function, cardiopulmonary function, metabolite levels, motor function, and physical fitness compared to the guideline group. Additionally, we anticipate that HIIT will lead to greater benefits in these areas. The findings from this study will provide valuable insights into the selection of appropriate exercise regimens for elderly sedentary individuals with T2DM.Ethics and disseminationThis study has been approved by the Ethics Review Committee of the Reproductive Hospital Affiliated with China Medical University (approval number: 202203). Informed consent will be obtained from all participants or their guardians. Upon completion, the authors will submit their findings to a peer-reviewed journal or academic conference for publication.Clinical trial registrationChinese Clinical Trial Registry, identifier ChiCTR2200061573.

Butylated hydroxytoluene (BHT) is an excellent antioxidant widely used in food, polymer materials, and other fields. In order to understand the hazards of BHT, it is necessary to study its thermal stability, oxidation properties, and reaction products. This paper investigated BHT's oxidation characteristics and products using a mini-closed pressure vessel test (MCPVT), UV radiation reaction method, iodometric method, and gas chromatography-mass spectrometry (GC–MS). The MCPVT results showed that no chemical reaction of BHT was observed under a nitrogen atmosphere even when the temperature was increased to 450 K, which indicated that it was stable. However, BHT was readily oxidized under an oxygen atmosphere with an initial oxidation temperature of 332 K. Notably, oxidation reactions can occur as low as 293 K under 365 nm UV radiations in the atmosphere. The kinetics of the initial oxidation of BHT was investigated. The kinetics of the reaction of BHT in MCPVT was a second-order reaction with the kinetic equation lnk = -1.2194 × 104(1/T) + 21.4. And Ea = 101.4 kJ mol−1. The difference is that a pseudo-first-order reaction was shown under UV radiation, with a linear relationship between the apparent activation energy and the logarithm of the light intensity (I): Ea = -1.878 lnI + 74.56, the apparent activation energy was significantly reduced compared to the former, indicating that UV light has a great effect on the oxidation of BHT. The peroxide value of the BHT oxidation product in MCPVT was determined with the iodometric method. When the reaction was carried out at 358 K for 8 h, the peroxide value of BHT was 3.2 mmol kg−1. The main oxidation products of BHT were identified with GC–MS, such as 2, 6-di-tert-butyl-p-benzoquinone, 1-(2, 4, 6-trihydroxyphenyl) butanone, 3, 5-di-tert-butyl- 4-hydroxybenzaldehyde, 3, 5-di-tert-butyl-4-hydroxyacetophenone. Based on these oxidation products, the oxidation pathway of BHT was described. In conclusion, the oxidation characteristics of BHT were studied in detail with MCPVT, and a method for evaluating thermal stability was developed. UV radiation made BHT more susceptible to oxidation reactions. These data provided a reference for BHT's storage, transportation, and safety evaluation.

Silicate solutions can improve the durability of concrete conveniently and effectively. To horizontally compare the enhancement effects of different composite silicate solutions, three types of silicate surface treatment agents were prepared by using sodium silicate, potassium silicate, and lithium silicate as the main agents, along with urea, sodium polyacrylate, catalysts, and fluoro-carbon surfactants as the adjuvants. Furthermore, their effects on the durability of concrete were compared. The results showed that silicate surface treatment could reduce the content of Ca(OH)2, increase the content of hydrated calcium silicate (C-S-H), and improve the compactness and hydrophobicity of the hardened cement surface. Although the three surface treatments enhanced the durability of concrete, the effects differed based on the complexities and mixtures. The sodium silicate compounded with potassium silicate performed the best of all three, wherein the content of the C-S-H gel increased by 389.8%, the permeability decreased by 60.6%, the water contact angle improved to 83.5° and the chloride ion resistance and freeze–thaw resistance of concrete increased by 36.7% and 37.34%, respectively, compared with the control sample.

Abstract Malania oleifera Chum is a unique renewable plant resource in China, its fruit oil has a high content of 15-tetracosenic acid, and it is a good raw material for the synthesis of cyclopentadecanone and cyclopentadecanolide. A Novel synthesis method of cyclopentadecanone and cyclopentadecanolide from vegetable oil was designed, and the synthesis yields of c cyclopentadecanone and cyclopentadecanolide were 38.5% and 63.0%, respectively. The effect of different ester groups on cyclization of α,ω-difatty acid alkyl ester in cyclopentadecanone synthesis, and effect of catalysts on cyclization ofω-hydroxycarboxylic acid triglyceride in cyclopentadecanolide synthesis were investigated. The designed synthesis strategy has the characteristics of less synthesis steps and high utilization efficiency of 15-tetracosenic acid, which has simple and economic.

The topography of human callosal fibers in the midsagittal corpus callosum (mid-CC), in terms of cortical termination, is inconsistent in the literature. Despite being a high-profile and controversial topic, heterotopic callosal bundles (HeCBs) have not been studied from a whole-brain perspective. Here, we used multi-modal magnetic resonance imaging data from Human Connectome Project Development to explore these two topographic aspects by combining whole-brain tractography based on multi-shell multi-tissue constrained spherical deconvolution, the post-tractography reducing-false-positive-streamline algorithm of Convex Optimization Modeling for Microstructure Informed Tractography 2, and the new cortex parcellation atlas of Human Connectome Project multi-modal parcellation, version 1.0. We proposed that the callosal streamlines would demonstrate a topological arrangement of coronal segments arranged from anterior to posterior, with each perpendicular to the long axis of the mid-CC following its natural curvature, and the adjacent segments overlapping one another owing to the existence of HeCBs. We found that the cortices connected by the coronal segments, from anterior to posterior, corresponded exactly to the cortices from anterior to posterior in the flattened cortical surfaces of this atlas, indicating the original relative positions of the neocortex before curling and flipping during brain evolution. For each cortical area defined by this atlas, the sum strength of the HeCBs was far greater than that of the homotopic callosal bundle. Our findings on the topography of the whole CC would help in further understanding the network between the bilateral hemispheres and preventing disconnection syndromes in clinical settings.

Abstract The reaction process of gaseous 1,3-butadiene following ultraviolet irradiation at the temperature range from 298 to 323 K under nitrogen atmosphere was monitored by UV–vis spectrophotometry. A gaseous mini-reactor was used as a reaction vessel and could be directly monitored in a UV–vis spectrophotometer. We investigated the reactivity and kinetics of 1,3-butadiene under non-UV and UV irradiation to evaluate its photochemical stability. A second-order kinetic model with 50.48 kJ·mol–1 activation energy fitted the reaction data for non-UV irradiation, whereas a first-order kinetic model was appropriate in the case of UV irradiation with activation energies of 19.92–43.65 kJ mol–1. This indicates that ultraviolet light could accelerate the photolysis reaction rate of 1,3-butadiene. In addition, the reaction products were determined using gas chromatography-mass spectrometry (GC–MS), and the reaction pathways were identified. The photolysis of 1,3-butadiene gave rise to various volatile products by cleavage and rearrangement of single C–C bonds. The differences between dimerization and dissociation of 1,3-butadiene under ultraviolet irradiation were elucidated by combining experimental and theoretical methods. The present findings provide fundamental insight into the photochemistry of 1,3-butadiene compounds.

Path planning is one of the research hotspots of unmanned surface vehicles (USVs) and a key technology for realizing their autonomy and intelligence. Aiming at the problem of local path planning for USVs, this paper elaborates on the application of various algorithms at the two levels of path search and trajectory optimization, introduces the latest research results in recent years and carries out an in-depth analysis of the characteristics and deficiencies of various algorithms. It then summarizes an improved method to adapt the algorithm to the motion characteristics of USVs, and finally gives a brief outlook on the development trends of local path planning for USVs, providing some ideas for future research in this field.

The harmonic drive (HD) is increasingly used due to its outstanding advantages, especially for equipment requiring high precision and a large gear ratio. This research is based on the Finite Element Method (FEM) and mechanical analysis to investigate stress calculation methods for the flexspline (FS), a significant component of HD transmission, providing a basis for assessing the durability and failure of the FS. First, the FS deformation and stress analysis model based on the FEM is proposed. Since the two boundary elements of the model have the form of a rotation and translational joint, which have not been provided, based on the stiffness matrix of the fixed beam to build the stiffness matrix for these elements, which completes the proposed analytical model. Then, the structures of an HD reduced are designed and applying the proposed force analysis model, the deformation and stress distributions of the FS are obtained. Finally, the theoretical safety factor is calculated and analyzed. The results of the simulation completely coincide with the theoretical calculation and show that the most concentrated stress is at the root of the teeth, which is the leading cause of the FS failure. So, the study as reference material for rapidly evaluating the stress state and calculating the safety when designing and optimizing the FS.

BackgroundThe increasing incidence of carbapenem-resistant bacterial infections has become a serious public health threat. This study aimed to investigate and analyze the current regional differences in carbapenem-resistant gram-negative bacteria (CRGN) in a major Province of China, and provide suggestions for preventing hospital infections.MethodsA questionnaire survey was used to obtain the current data on CRGN from 36 hospitals in Shandong Province, China, from 2019 to 2020. The association between the detection rates and discovery rates of CRGN and the use of antibacterial drugs was analyzed using Spearman's correlation coefficient. In addition, we compared the detection rates of CRGN and antibacterial drugs using hospitals categorized according to different levels and economic areas using the Kruskal-Wallis test.ResultsThe average detection rates of CRGN across the 36 hospitals varied from 1.91% to 66.04%. The discovery rate of carbapenem-resistant Enterobacteriaceae (CRE) and carbapenem-resistant Acinetobacter baumannii (CRAB) remained below 5‰, and that of carbapenem-resistant Pseudomonas aeruginosa (CRPA) was below 10‰. Except for CRAB, the correlations between the detection rate and antimicrobial drug use intensity and carbapenem drug use percentage were 0.11–0.29 and 0.31–0.47, respectively. Carbapenem drug use was higher in the provincial hospital group than in the prefecture-level hospitals (P < 0.05), and that in the high-economic regional hospital group was higher than in the low-economic regional hospital group (P < 0.05).ConclusionsThe detection and discovery rates of CRE were low, and those of CRAB were high in Shandong Province. Larger hospitals have higher carbapenem drug use. These results can be used as a reference for preventing CRGN infections in developing countries and provide a basis for regional carbapenem resistance prevention and control strategies.

1,3-Butadiene is the simplest conjugated diene, which is widely used in polymer materials, organic synthesis, and other fields. The investigation of its thermal stability and oxidation characteristics is necessary for production, transportation, and use safety. The pressure and temperature behavior of the autoxidation reaction of 1,3-butadiene with oxygen were determined using a custom-designed mini closed pressure vessel test (MCPVT). The effects of free radical initiators CHP and AIBN on the oxidation reaction were investigated. The thermal decomposition characteristics of oxidation products were measured by differential scanning calorimetry (DSC), and its hazards were discussed. The results showed that the oxidation reaction of 1,3-butadiene was easy to occur. Moreover, the activation energies of autoxidation, CHP-initiated oxidation, and AIBN-initiated oxidation reaction were 20.85 kJ·mol−1, 33.30 kJ·mol−1, and 56.27 kJ·mol−1, respectively. In addition, the oxidation products were analyzed by headspace sampler-gas chromatography-mass spectrometry (HS-GC–MS), GC–MS, and iodometry. Some of 1,3-butadiene oxidation products under three conditions are the same, for example, 3-butene-1,2-diol, 4-vinylcyclohexene, 2(5H)-furanone, 2-propen-1-ol, and 2,6-cyclooctadien-1-ol. According to the reaction products, the oxidation reaction pathway of 1,3-butadiene was described. The research results are significant for avoiding fire and explosion accidents in the production, transportation, and application of 1,3-butadiene.

Escherichia coli O157:H7 ( E. coli O157:H7) can induce severe diseases in animals and humans that result in significant public health problems. Therefore, the development of rapid and visual detection methods to diagnose E. coli O157:H7 infections and monitor its prevalence is critical for the prevention and control purposes. A colorimetric loop-mediated isothermal amplification (LAMP) assay was utilized to detect E. coli O157:H7. A DNA extraction kit and Flinders Technology Associates (FTA) cards were used to extract nucleic acid in conjunction with colorimetric LAMP detection. The method developed effectively distinguished E. coli O157:H7 from other pathogens with a detection limit of 25 CFU/mL in spiked stool samples. In addition, the nucleic acid of these samples was easily extracted and transported with an FTA card at room temperature. The entire detection process was completed within 35 min using simple constant-temperature equipment. The colorimetric LAMP method with FTA card-based nucleic acid purification was shown to rapidly detect E. coli O157:H7 with sensitivity and specificity. This visual method is expected to be widely used to control E. coli O157:H7 infections, particularly in resource-limited settings.

In this paper, the corrosion performance of galvanized steel was investigated in a simulated marine environment, under UV irradiation coupling with an alternating wet and dry cycle in a NaCl solution. The surface morphology, composition, and corrosion performance of galvanized steel before and after different alternating wet and dry corrosion under UV irradiation were investigated. The results show that the corrosion current density gradually increases and the corrosion resistance decreases as a function of the alternating wet and dry corrosion cycles. Meanwhile, UV irradiation accelerates the increase in the corrosion current density and the decrease in the corrosion resistance. In addition, the corrosion product ZnO shows a semiconductor property, and the photo-induced electrons and holes produced under UV can participate in the corrosion reaction and promote the formation of loose corrosion products Zn(OH)2, Zn5(OH)8Cl2, and Al2Cl3(OH)5·4H2O, thus accelerating the corrosion of galvanized steel in the atmosphere environment.

The volume control tank (VCT) is an important facility in the primary circuit of nuclear power plants. During the normal operation of nuclear power plants, the mass transfer between the gas and liquid phases occurs in the VCT at all times. It is driven by submerged jets, which may cause potential risks to the operational safety of nuclear power plants. It is necessary to conduct an in-depth study to gain a deeper understanding of the gas–liquid mass transfer behavior in the VCT. In this paper, a new gas–liquid mass transfer model is developed that combines a surface divergence model with a CFD model to accurately simulate the mass transfer process of the gas phase into the liquid phase. The simulation data were verified by the experimental results. The deviation between the simulation results and experimental results is less than 6.55%. Based on this model, a simulation study was carried out for the effect of structural parameters of the VCT on gas–liquid mass transfer. The results show that the double-vortex structure above the jet inlet, the surface jet at the gas–liquid interface, and the vortex at the end of the jet are the three factors dominating the gas–liquid mass transfer in the VCT. The gas–liquid mass transfer can be influenced by the jet diameter since the jet diameter has a remarkable effect on the Kolmogorov scale and the macroscopic flow field structure. Moreover, both the Kolmogorov scale and the macroscopic flow field structure can be affected by the jet height. However, these two effects cancel each other out. Thus, the influence of the jet height on the gas–liquid mass transfer rate is negligible.

ObjectivesConducting studies on contaminant dispersion during the door-opening process of isolation rooms and quantitatively comparing and evaluating the diffusion characteristics of contaminated air under different negative pressure conditions is of great significance for the design of negative pressure systems for the isolation rooms of ships. MethodsBased on the large eddy simulation (LES) method and a combination of tracer gas component transport equations, numerical simulations were conducted to investigate contaminated air dispersion during the door-opening process of isolation rooms. The flow field characteristics and pollutant dispersion process during the dynamic opening of the door under different differential pressure conditions were then compared and analyzed. Results The results show that the sensitivity analysis of mesh resolution and time step with total pollutant diffusion as the evaluation index can ensure the reliability of the LES simulation results. Further analysis shows that under the combination of different differential pressures and door-opening induced flows, there is a significant difference between the magnitude of the fluid velocity peak and the time when the peak appears. Increasing the negative pressure value of the isolation room can reduce the peak of pollutant diffusion and shorten the time for the diffused pollutant to return to the isolation room under the differential pressure. ConclusionsThe results obtained in this paper can provide guidance for the design of ship isolation rooms.

ObjectivesAiming at improving the schematic design efficiency of ship air-conditioning ventilation system and reducing the difficulty of data management, a rapid schematic generation method for this purpose based on knowledge components is proposed.MethodsFirst, the design process for the schematic design of the air-conditioning ventilation system is analyzed, and the knowledge component model, entity modeling and instantiation process defined on this basis. Next, combined with the design characteristics of the air-conditioning ventilation system, the business model and data exchange model are designed on the basis of the knowledge component. Finally, a prototype system of schematic design is developed using AutoCAD and PDM, then verified through application in actual engineering design.ResultsThe result shows that the schematic design efficiency of the air-conditioning ventilation system is increased by 43.5%.ConclusionsThis method can be widely used in the schematic design of ship system. It can greatly improves the design efficiency and the capability of data management, and has certain value in practical application.

Abstract In present study, the effects of carbon sources on compost process and quality were evaluated in the lab-scale sewage sludge (SS) composting. The composting experiments were performed for 32 days in 5 L reactors. The results showed that carbon sources could change the nitrogen conversion and improve the compost quality. Especially, the readily degradable carbon source could promote organic matter degradation, improve nitrogen conversion process and accelerate compost maturation. The addition of glucose and sucrose could increase dissolved organic carbon, CO2 emission, dehydrogenase activity, nitrification and germination index during the SS composting. That's because glucose and sucrose could be quickly used by microbes as energy and carbon source substance to increase activity of microbes and ammonia assimilation. What's more, the NH3 emission was reduced by 26.9% and 32.1% in glucose and sucrose treatments, respectively. Therefore, the addition of readily degradable carbon source could reduce NH3 emission and improve compost maturity in the SS composting.

Aiming at the problem of extracting characteristic frequency of flexible thin-walled bearings，a feature frequency extraction algorithm combining principal component analysis （PCA） and multi-point optimally adjusted minimum entropy deconvolution （MOMEDA） is proposed. In the algorithm，PCA is used to perform noise reduction processing on the original signal to obtain a reconstructed signal. The multipoint kurtosis （MKurt） is used to extract the period of the periodic shock signal in the reconstructed signal，and the theoretical period is corrected to obtain an accurate deconvolution period，enhance the reconstructed signal through MOMEDA，highlight its periodic impact，and extract the characteristic frequency more effectively. This method is applied to the fault feature frequency extraction of flexible thin-walled bearings，and compared with the maximum correlation kurtosis deconvolution （MCKD） algorithm. The results show that this method can separate bearing fault shocks from periodic shocks caused by the alternation of the bearing's long and short axes，eliminate the interference of such normal periodic shocks，and effectively extract the fault characteristic frequency in the signal. The effect is better than the maximum correlation kurtosis deconvolution algorithm.

Abstract Background Lignocellulose is the most abundant and renewable biomass resource on the planet. Lignocellulose can be converted into biofuels and high-value compounds; however, its recalcitrance makes its breakdown a challenge. Lytic polysaccharide monooxygenases (LPMOs) offer tremendous promise for the degradation of recalcitrant polysaccharides. Chaetomium thermophilum, having many LPMO-coding genes, is a dominant thermophilic fungus in cellulose-rich and self-heating habitats. This study explores the genome, secretomes and transcript levels of specific genes of C. thermophilum. Results The genome of C. thermophilum encoded a comprehensive set of cellulose- and xylan-degrading enzymes, especially 18 AA9 LPMOs that belonged to different subfamilies. Extracellular secretomes showed that arabinose and microcrystalline cellulose (MCC) could specifically induce the secretion of carbohydrate-active enzymes (CAZymes), especially AA9 LPMOs, by C. thermophilum under different carbon sources. Temporal analyses of secretomes and transcripts revealed that arabinose induced the secretion of xylanases by C. thermophilum, which was obviously different from other common filamentous fungi. MCC could efficiently induce the specific secretion of LPMO2s, possibly because the insert in loop3 on the substrate-binding surface of LPMO2s strengthened its binding capacity to cellulose. LPMO2s, cellobio hydrolases (CBHs) and cellobiose dehydrogenases (CDHs) were cosecreted, forming an efficient cellulose degradation system of oxidases and hydrolases under thermophilic conditions. Conclusions The specific expression of LPMO2s and cosecretion of hydrolases and oxidases by the thermophilic fungus C. thermophilum play an important role in cellulose degradation. This insight increases our understanding of the cellulose degradation under thermophilic conditions and may inspire the design of the optimal enzyme cocktails for more efficient exploration of biomass resources in industrial applications.

Magnolol, known to have extensive biological activities, is the major bioactive ingredient isolated from the root and stem bark of Magnolia officinalis. However, the clinical application of magnolol is limited by poor aqueous solubility and absorption. The aim of this study is to develop novel mixed micelles and nanosuspensions composed of two biocompatible copolymers, Soluplus® and Poloxamer 188, and to improve the solubility and oral bioavailability of magnolol. The magnolol-loaded mixed micelles (MMs) and magnolol nanosuspensions (MNs) were prepared to use film hydration and antisolvent methods, respectively. The optimal MMs and MNs formulations were prepared to use magnolol, Soluplus®, and Poloxamer 188 in ratios of 1:12:5 and 2:1:1, respectively. The average particle size of MMs was 111.8 ± 14.6, and MNs was 78.53 ± 5.4 nm. The entrapment and drug loading efficiency for MMs were 89.58 ± 2.54% and 5.46 ± 0.65%, correspondingly. The drug loading efficiency of MNs was 42.50 ± 1.57%. In the in vitro release study, MMs showed a slow drug release while that of MNs was fast. The results of the Caco-2 transcellular transport study indicated that both MMs and MNs increased the permeation of magnolol. MMs and MNs markedly promoted gastrointestinal drug absorption by 2.85 and 2.27-fold, respectively, as shown in the pharmacokinetics study. These results indicated that both MMs and MNs formulations prepared with Soluplus® and Poloxamer 188 are promising drug delivery systems for improving the oral absorption of insoluble drugs in the gastrointestinal tract.

Purpose Obesity is a significant risk factor for pelvic organ prolapse (POP), but the effects of obesity on outcomes of surgery for POP are poorly understood. The aim of this study was to assess the relationship between POP symptomatology, subjective outcomes of surgery and body mass index (BMI) in women undergoing vaginal hysterectomy for POP. Methods Pre- and postoperative data from a validated pelvic floor questionnaire (electronic Personal Assessment Questionnaire-Pelvic Floor) were collected prospectively from 60 women undergoing vaginal hysterectomy for POP. Of these, 20 were normal weight (BMI 18.5–24.9 kg/m2), 20 were overweight (BMI 25–29.9 kg/m2), and 20 were women with obesity (BMI 30–34.9 kg/m2). The relationship between BMI and symptom scores for prolapse, impact on vaginal symptoms on quality of life (VS-QoL) and ‘overall change in condition’ was assessed. Pre- and postoperative symptom scores were compared using repeated mixed analysis of variance test for BMI as a categorical variable (normal, overweight, and obese). Spearman rank order correlation test was carried out to evaluate BMI as a continuous variable. All women underwent vaginal hysterectomy using a standardized technique. Results Overall, 93% of women reported improvement in their condition. The main finding was that ‘overall change in condition’ was negatively correlated with increasing BMI (rs=-0.324, P=0.028). Irrespective of BMI, significant improvements were observed in symptoms of prolapse and VS-QoL at 3-month postoperation. Conclusions With increasing BMI, women are likely to report lower levels of satisfaction following prolapse surgery, despite reporting equivalent improvements in symptoms. BMI is known to affect how individuals perceive their general health and well-being with obese individuals reporting poorer levels of subjective health status. Women with obesity may perceive change in their condition after prolapse surgery differently to women of normal weight. Reduction of weight prior to prolapse surgery could be considered in obese women to improve subjective outcomes of surgery.

Cement emulsified asphalt (CEA) mortars achieve insufficient bond strength with substrate cement concrete slab. To ameliorate problems emerging from this, the emulsified asphalt (EA) in CEA mortars was partly replaced by epoxy emulsion (EE) at contents of 0%, 10%, 20%, and 30%, yielding CEA mortars with enhanced properties. The bond strength, mechanical strength, toughness, and durability (including drying shrinkage and erosion resistance) of modified CEA mortars were assessed. The results showed that partial replacement of EA with EE improved the bond strength, mechanical strength, drying shrinkage, and erosion resistance of CEA mortars. A good correlation was found between the proportions of the EE replacement and the bond strength of CEA mortars. Partial replacement of EA with a small amount of EE exerted no significant effect on the toughness of CEA mortar. The stronger network structure of CEA mortars containing EE improved the compactness, thus improving the performance of CEA mortars. Based on these findings, EE is suggested as partial replacement of EA for enhancing the properties of CEA mortars.

To resolve the limited large-scale methods of disposal of low calcium fly ash with poor activity, based on the double excitation principle, clinker and desulfurized gypsum are used as alkali/salt activators to activate fly ash and slag, avoiding the inconvenience of strong alkali activating fly ash in industry. Firstly, the strength test of a filling body with multiple ratio composite cementing material is carried out, and the weight coefficient of each material to strength is analyzed by grey correlation degree. The composition of the hydration products, microstructure, and pore structure of the filling body was analyzed by X-ray diffractometer, scanning electron microscope, thermogravimetric test, and mercury compression test. The strength mechanism of the cemented body was confirmed. The results show that cemented backfill prepared by composite cementitious material, which contained high content and low-quality fly ash, can meet the strength requirements of subsequent backfill in a mine. The degree of composite cementitious material influence on 7 d strength is slag > desulfurized gypsum > fly ash > clinker; the degree of influence on 28 d strength is: fly ash > slag > desulfurized gypsum > clinker. The main hydration products of the composite cementable material with high content low-quality fly ash are C–S–H gel and ettringite, and the unreacted fly ash particles can still be seen at 28 d. As the curing age grows, the difference in the number of hydration products under different proportioning conditions has a weaker effect on the strength, while the influence of raw materials and product morphology on the pore structure determines the development trend of the strength. Therefore, the threshold pore size can be used to characterize the strength advantages and disadvantages reasonably.

Background: Immunological and inflammatory mechanisms play an important role in schizophrenia. The neutrophil-to-lymphocyte ratio (NLR) is a value obtained by dividing the absolute number of neutrophils by the absolute lymphocyte count and represents a biomarker of systemic inflammatory response. There are studies investigating NLR association with psychopathology. However, the relationship has been only studied in small numbers of patients with schizophrenia, which leads to conflicting results and makes the meta-analytic data difficult to interpret. The aim of this study is to perform large-scale cross-sectional analysis on the potential correlation between NLR and disease severity in schizophrenic patients with or without medication.Methods: This cross-sectional retrospective study was conducted in Nanjing Medical University Affiliated Brain Hospital. We identified inpatients with schizophrenia between July 12, 2018 and March 27, 2019 and collected data of NLR, the Clinical Global Impression Severity scale (CGI-S) score and the Brief Psychiatric Rating Scale (BPRS) score.Results: The records of 1,144 identified patients (10.8% drug-free patients) were analyzed. We found that NLR was significantly decreased in schizophrenic patients after antipsychotic administration and there was the discrepant correlation between NLR and psychiatric symptoms in patients with or without antipsychotic medication. The results of multivariate logistic regressions showed that NLR was positively associated with the severity of disease (i.e., the CGI-S score and the BPRS total score) in drug-free patients, and it was negatively associated with the BPRS negative symptoms (i.e., the BPRS negative symptoms score) in drug-therapy patients.Conclusion: The study is the first to confirm the hypothesis that NLR is independently associated with severe psychopathology in schizophrenia and is changed by antipsychotic administration.

The present study included lab-scale sewage sludge (SS) composting amended by molasses and spent mushroom substrate (SMS) in 5 L composting reactor system. The influence of molasses and SMS amendment on nitrogen loss and humification of SS composting was evaluated. The results showed that SMS amendment, especially combination with molasses raised composting temperature, increased CO2 volatilization, promoted organic matter degradation, improve germination index and humification process. The addition of SMS and molasses contain carbohydrates used as carbon source and energy substance by microorganisms could increase microbial activity and ammonia assimilation. In the SMS + molasses treatments, NH3 volatilization was reduced by 33.1%–37.3% and N2O volatilization was only 17.8%–25.4% of that in the control treatment, furthermore, the nitrogen loss rate was reduced by 27.2%–32.2%. Consequently, the addition of SMS and molasses improved the compost maturity and reduced nitrogen loss in the SS composting process.

Cement asphalt emulsion mixture (CAEM) presents low early-age strength and poor flowability, which limits its application range at a certain degree. In this paper, CAEM with high early-age strength and flowability was proposed. The flowability, compressive strength, flexural strength of CAEM at different periods and 28 days elastic modulus of CAEM were investigated. In addition, evolution of composition and microstructure of CAEM was analyzed by X-ray diffraction (XRD), scanning electronic microscope (SEM), and mercury intrusion porosimetry (MIP). The results indicated that the compressive strength of CAEM can be enhanced quickly in several hours. It could achieve 17–24 MPa at 6 h and almost reached 79–90% of the 28 days compressive strength. SEM and XRD analysis found that the hydration products in CAEM at different periods were obviously different. The hydration products of 2 h filled the micro pores of the mixture. After 28 days, the hydration products were connected to each other, resulting in a denser structure. The results of MIP analysis showed that the pore cumulative volume of CAEM was similar for 2 h and 28 days samples. These results testified that CAEM had high early-age strength.

FxLMS (Filtered-x Least Mean Square) algorithm is widely used in the field of AVC (active vibration control) for its good convergence and strong adaptability. However, the convergence rate and steady-state error are mutually restricted for the fixed step FxLMS algorithm. Increasing step size μ to accelerate the convergence rate will result in larger steady-state error and even cause control divergence. In this paper, a new DVSFxLMS (error signal Differential term feedback Variable Step size FxLMS) algorithm is proposed by establishing nonlinear function between μ and error signal, while using differential term of the error signal as the feedback control function. Subsequently, a DVSFxLMS controller is designed to carry out the AVC simulation and experiments on cantilever beam with PSA (piezoelectric stack actuator). Simulation and experimental results show that the proposed DVSFxLMS algorithm has faster convergence rate and smaller steady-state error than the traditional FxLMS algorithm, which also has strong antinoise ability and adaptive control ability to quickly track the variable external disturbance.

Abstract Endoglucanases are increasingly applied in agricultural and industrial applications as a key biocatalyst for cellulose biodegradation. However, the low performance in extreme conditions seriously challenges the enzyme’s commercial utilization. To obtain endoglucanases with substantially improved activity and thermostability, structure-based rational design was carried out based on the Chaetomium thermophilum β-1,4-endoglucanase CTendo45. In this study, five mutant enzymes were constructed by substitution of conserved and noncatalytic residues using site-directed mutagenesis. Mutants were constitutively expressed in Pichia pastoris, purified, and ultimately tested for enzymatic characteristics. Two single mutants, Y30F and Y173F, increased the enzyme’s specific activity 1.35- and 1.87-fold using carboxymethylcellulose sodium (CMC-Na) as a substrate, respectively. Furthermore, CTendo45 and mutants exhibited higher activity towards β-D-glucan than that of CMC-Na, and activities of Y173F and Y30F were also increased obviously against β-D-glucan. In addition, Y173F significantly improved the enzyme’s heat resistance at 80 °C and 90 °C. More interestingly, the double mutant Y30F/Y173F obtained considerably higher stability at elevated temperatures but failed to inherit the increased catalytic efficiency of its single mutant counterparts. This work gives an initial insight into the biological function of conserved and noncatalytic residues of thermostable endoglucanases and proposes a feasible path for the improvement of enzyme redesign proposals.

Abstract A multicenter prospective surveillance on dialysis events was carried in 33 dialysis centers in China. Maintenance hemodialysis (HD) outpatients who were dialyzed on the first two days of each month during 2014 were monitored for dialysis events and other infections. During the one-year period, 52,680 patient-months were monitored. Fistula and tunneled or non-tunneled central line were used for 73.70%, 15.70% and 8.85% of vascular access, respectively. There were 773 dialysis events occurred in 671 patients including 589 IV antimicrobial starts, 74 positive blood cultures and 110 local access site infections (LASI). The incidence of dialysis events was 1.47 per 100 patient-months. Among the 74 cases with bloodstream infection (BSI), 38 were access-related BSI (ARB) and there were therefore 148 cases with vascular-related infection (VAI; 38 ARB and 110 LASI). There were 740 cases (1.40 per 100 patient-months) with infections other than BSI and LASI, most (79.19%) of which were respiratory tract infections. For those with dialysis events, there were 425 cases (425/671, 63.34%) admitted to hospital and 12 cases of death (12/671, 1.79%). In conclusion, the surveillance revealed a relatively low incidence of dialysis events and the surveillance may be tailored to target those using central lines in resource-limited settings.

Objectives Stillbirth is an important and yet relatively unacknowledged public health concern in many parts of the world. Public awareness of stillbirth and its potentially modifiable risk factors is a prerequisite to planning prevention measures. Cultural and regional differences may play an important role in awareness and attitudes to stillbirth prevention. The objective of this study was to evaluate and compare the awareness of stillbirth among hospital staff in Qatar and the UK, representing two culturally different regions.Study design An online population survey for anonymous completion was sent to the hospital email accounts of all grades of staff (clinical and non-clinical) at two hospitals in Qatar and one tertiary hospital Trust in the UK. The survey was used to gather information on the participants’ demographic background, the experience of stillbirth, knowledge of stillbirth, awareness of information and support sources, as well as attitude towards investigation and litigation. Data were analysed using descriptive and comparative statistics (Chi-Square test and Fisher’s exact test).Results 1002 respondents completed the survey, including 349 in the Qatar group and 653 in the UK group. There were significant differences in group demographics in terms of language, religion, gender, nationality and experience of stillbirth. The groups also differed significantly in the knowledge of stillbirth, its incidence and risk factors. The two groups took different views on apportioning blame on healthcare services in cases of stillbirth. The Qatar group showed significantly less awareness of available support organisations and relied significantly more on online sources of information for stillbirths (p

A reasonable micro-pits texture has been initially proved that it can improve friction characteristics between wood and cemented carbide surface and reduce surface friction coefficient. In order to study the cutting performance of the micro-texture when it is applied to the cutting tool for cutting wood more effectively, this paper selected micro-pit texture for studying influence of surface micro-texture cutting tool on wood cutting performance and cutting temperature, finding that when micro-pit cemented carbide cutting tool is adopted for turning the northeast China ash (Fraxinus spp.), it can reduce cutting force of turning and surface friction coefficient between rake face and cuttings. Moreover, for type A and type B cutting tools, when the texture parameters are that the diameter of the micro-pit is 80μm, the depth of the micro pit is: 10μm, area occupancy is 20% and the diameter of the micro-pit is 120μm, the depth of the micro-pit is 10μm and the area occupancy is 20%, the effect generated is the best. When a texture cutting tool is used for cutting, the decrease of the highest temperature in the cutting area is not very great, but the average temperature in the cutting area changes a lot, which is mainly caused by that micro-texture is processed at a position of the rake face close to the main cutting edge and that the highest temperature of cutting is mainly generated on the contact point between tool tip and wood. A reasonable micro-texture parameter can form a layer of liquid lubricating film on the up and down contact surfaces such that the direct contact between cemented carbide and northeast China ash is changed into indirect contact between lubricating films formed by the liquid so as to reduce the surface friction coefficient.

Vibration-based diagnosis has been employed as a powerful tool in maintaining the operating efficiency and safety for large rotating machinery. However, the extraction of malfunction features is not accurate enough by using traditional vibration signal processing techniques, owing to their intrinsic shortcomings. In this paper, the relationship between effective eigenvalues and frequency components was investigated, and a new characteristic frequency separation method based on PCA (CFSM-PCA) was proposed. Certain feature frequency could be purified by reconstructing the specified eigenvalues. Furthermore, three significant perspectives were studied via the distribution of effective eigenvalues, and theoretical derivations were subsequently illustrated. More importantly, this proposed scheme could also be used to synthesize axis orbits of larger machines. Purified curves were so explicit and the CFSM-PCA exhibited higher efficiency than harmonic wavelet and wavelet packet.

In this study, a numerical model of the tangential tensioning stress distribution of a circular saw blade tensioned by multi-spot pressure was established using theoretical analysis, and the tangential tensioning stress distribution of the circular saw blade calculated by the model was shown to be true and reliable. The effect of yield strength of the circular saw blade on the distribution of tangential tensioning stress was studied using the numerical model. The research achievements showed that a circular saw blade made with high-strength or ultra-high-strength steel yielded a better tensioning effect during the multi-spot pressure tensioning process, which could promote the application of a circular saw blade made by high-strength or ultra-high-strength steel.

In this study, a mathematical model of tangential tensioning stress in the edge of a circular saw blade tensioned by multi-spot pressure was established by theoretical analysis for the quality control of circular saw blades. The multi-spot pressure tensioning process was assumed to include three mechanical processes: the one-spot pressure process; the process of elastic deformation of a disk with a through-hole subjected to uniform, radial compressive stress; and the stress superposition process. The tangential tensioning stress on the edge of the circular saw blade could be accurately predicted by the established mathematical model. The model for the tangential tensioning stress on the edge of the circular saw blade tensioned by multi-spot pressure was shown to be correct by measured values.

Solid dispersions of tanshinone IIA (TanIIA) using hydroxyapatite (HAp) as the dispersing carrier (TanIIA-HAp SDs) were prepared by the solvent evaporation method. The formed solid dispersions were characterized by scanning electron microscopy (SEM), differential scanning calorimetry analysis (DSC), X-ray powder diffraction (XRPD) and Fourier transforms infrared (FTIR) spectroscopy. The in vitro dissolution rate and the stability of TanIIA-HAp SDs were also evaluated. DSC and XRPD showed that TanIIA was changed from a crystalline to an amorphous form. FTIR suggested the presence of interactions between TanIIA and HAp in solid dispersions. The result of an in vitro dissolution study showed that the dissolution rate of TanIIA-HAp SDs was nearly 7.11-folds faster than free TanIIA. Data from stability studies for over one year of TanIIA-HAp SDs performed under room temperature revealed no significant differences in drug content and dissolution behavior. All these results indicated that HAp may be a promising carrier for improving the oral absorption of TanIIA.