基于MFCC与神经网络的小蠹声音种类自动鉴别

昆虫发出的各种声音具有种间特异性,是非常可靠的分类依据。利用这一特性,本实验旨在探索一种对昆虫自动分类的新方法。本实验录制了红脂大小蠹、云南切梢小蠹、短毛切梢小蠹和华山松大小蠹4种小蠹虫的胁迫声,利用Adobe Adition2.0对每个声音文件进行降噪,再将其截取成只含有一个脉冲组的声音片段。在MATLAB环境下对这些声音片段进行端点监测并提取12维的MFCC（Mel频率倒谱系数）,然后将此特征参数输入BP神经网络进行训练和检测。设置训练样本数为20、40、60、80、100,4种小蠹检测样本数分别为54、95、54、50,结果显示识别率随着训练样本数的增加而提高,在训练样本量为100时的最高识别率达到98.14%,平均识别率为93.29%,收到了较好的效果。为了验证小蠹种类数对识别率的影响,本实验对4种小蠹进行了两两比较,结果显示总体上高于4种一起识别的结果。     

Methods of Betulin Extraction from Birch Bark

Betulin is the most popular of the known triterpenoids of the lupan series. It has valuable pharmacological properties. It exhibits antibacterial, antiviral, antitumor, hypolipidemic and other types of activity. The prospects of using betulin in medicine, pharmacology, and veterinary medicine require the development of effective methods for obtaining it from waste from the woodworking industry. Therefore, the question arises of the need to develop a technology for isolating and purifying triterpenoids from birch bark in large quantities. This review contains a variety of methods for the isolation of betulin. The advantages and disadvantages of the proposed methods are described. The following methods are considered: vacuum sublimation after preliminary alkaline; vacuum pyrolysis; supercritical extraction with carbon dioxide or mixtures of carbon dioxide with various solvents; extraction with organic solvents. Also, the method of microwave is described, it is activation on the example of the Kyrgyz birch (Betula kirghisorum), this is an endemic species that has not been studied before, growing on the territory of the Republic of Kazakhstan.     

Phytochemical Investigation of Cordia africana Lam. Stem Bark: Molecular Simulation Approach

Background: The current work planned to evaluate Cordia africana Lam. stem bark, a traditionally used herb in curing of different ailments in Africa such as gastritis and wound infections, based on phytochemical and antibacterial studies of two pathogenic microorganisms: methicillin-resistant Staphylococcus aureus (MRSA) and Helicobacter pylori. Methods: High performance liquid chromatography (HPLC) profiling was used for qualitative and quantitative investigation of the ethanol extract. The minimum inhibitory concentration (MIC) of the ethanolic extract and isolated compounds was estimated using the broth microdilution method and evidenced by molecular dynamics simulations. Results: Four compounds were isolated and identified for the first time: α-amyrin, β-sitosterol, rosmarinic acid (RA) and methyl rosmarinate (MR). HPLC analysis illustrated that MR was the dominant phenolic acid. MR showed the best bacterial inhibitory activity against MRSA and H. pylori with MIC 7.81 ± 1.7 μg/mL and 31.25 ± 0.6, respectively, when compared to clarithromycin and vancomycin, respectively. Conclusion: The antibacterial activity of the stem bark of Cordia africana Lam. was evidenced against MRSA and H. pylori. Computational modeling of the studied enzyme-ligands systems reveals that RA and MR can potentially inhibit both MRSA peptidoglycan transpeptidases and H. pylori urease, thereby creating a pathway via the use of a double target approach in antibacterial treatment.     

根系表皮形态对根–土拉拔力学行为的影响

研究选取小叶榕和大叶伞两种植物来开展室内根–土拉拔试验,分析根系的表皮形态及其基本拉伸力学特性对根–土相互作用的影响规律和机理。试验结果表明：两种植物根系拉拔力–位移曲线均呈现3个变化阶段,根–土界面最大摩擦力随根径和法向载荷的增大而增大,根皮粗糙度较大的根系其界面摩擦力较大;随着土颗粒对根皮表面挤压力的增大,表皮粗糙度和拉伸弹性模量共同影响根–土界面的最大摩擦力。相关研究成果可为生态护坡提供科学支撑。

     

Taphonomy of prehistoric bark in a salt environment at the archaeological site in Hallstatt,Upper Austria – An analytical approach based on FTIR spectroscopy

Taphonomy of subfossil bark was assessed in Hallstatt, Upper Austria. Samples from the Bronze Age were compared with recent corresponding material from the same site. Preservation of the prehistoric samples was caused by storage in a salt and clay mixture. FTIR spectroscopy was used to determine differences in material chemistry. Principal Component Analysis was applied to display the segregation of the data set according to the different factors and to display the strength of the effects. Results revealed that deacetylation processes dominated aging processes. Focusing on two band regions at around 1730 and 1230 cm⁻¹ a clear separation was achieved. Additionally some samples were selected for further analyses to investigate the influence of the inorganic matrix. Thermal analyses demonstrated an ash content of more than 15%_mass. X-ray diffractometry revealed the presence of salt (dominant), gypsum, pyrite, quartz, and calcite minerals.     

Retention mechanism of calcium ferrite and compositions of ash on selenium during chemical looping gasification

Selenium pollution by coal utilization is of increasing concern. Calcium-iron (Ca–Fe) oxygen carriers (OCs) and alkali metal ions have strong inhibitory effects on selenium, which can reduce the emissions of selenium vapor. The retention mechanisms of selenium by Fe₂O₃, CaFe₂O₄, Ca₂Fe₂O₅ and bottom ash are investigated during chemical looping gasification (CLG). Iron-based OC can oxidize H₂Se(g) to SeO₂(g); furthermore, lattice oxygen is released by Fe₂O₃, contributing to the formation of an Fe–O–Se structure to retain selenium and form selenite. Because calcium ferrite is poorly oxidizing, it cannot oxidize H₂Se(g), but the CaO produced when OCs are reduced can react with H₂Se(g) to form CaSe(s), and this process can be promoted by H₂S(g). The best retention rates reached 32.301% when Ca₂Fe₂O₅ was used. In the cyclic experiment, the selenium retention of the bottom ash gradually increases. Alkali metal ions in bottom ash are the main factor in retaining selenium. Ca²⁺ and Mg²⁺ do not easily vaporize due to their high melting points; therefore, their selenium retention is significantly better than that of K⁺ and Na⁺. This research provided a new idea for the removal of selenium by using OCs and bottom ash particles during CLG.