Properties of Bark Particleboard Bonded with Demethylated Lignin Adhesives Derived from Leucaena leucocephala Bark

Lignin extraction from bark can maximize the utilization of biomass waste,offer cost-effectiveness,and promote environmental friendliness when employed as an adhesive material in bark particleboard production.Particles of fine(0.2 to 1.0 mm),medium(1.0 to 2.5 mm),and coarse(2.5 to 12.0 mm)sizes,derived from the bark of Leucaena leucocephala,were hot-pressed using a heating plate at 175℃for 7 min to create single-layer particleboards measuring 320 mm×320 mm×10 mm,targeting a density of 700 kg/m^(3).Subsequently,the samples were trimmed and conditioned at 20℃and 65%relative humidity.In this study,we compared bark particleboard bonded with urea formaldehyde(UF)adhesive to fine-sized particleboard bonded with demethylated lignin adhesive.The results indicated that bark particleboards utilizing demethylated lignin and UF adhesives exhibited similar qualities.Coarse particleboard showed differences in modulus of elasticity(MOE)and modulus of rupture(MOR),while medium-sized particles exhibited significant variations in moisture content(MC)and water absorption(WA).Furthermore,the thickness swelling of coarse and medium-sized particles under wet and oven-dried conditions exhibited notable distinctions.Overall,the demethylated lignin adhesive extracted from L.leucocephala bark demonstrated similar quality to UF adhesive,with particle size correlating inversely to the strength of the bark particleboard.

The rate of deadwood decomposition processes in tree stand gaps resulting from bark beetle infestation spots in mountain forests

Decaying wood is an essential element of forest ecosystems and it affects its other components.The aim of our research was to determine the decomposition rate of deadwood in various humidity and thermal conditions in the gaps formed in the montane forest stands.The research was carried out in the Babiog orski National Park.The research plots were marked out in the gaps of the stands,which were formed as a result of bark beetle gradation.Control plots were located in undisturbed stands.The research covered wood of two species–spruce and beech in the form of cubes with dimensions of 50 mm×50 mm×22 mm.Wood samples were placed directly on the soil surface and subjected to laboratory analysis after 36 months.A significant influence of the wood species and the study plot type on the physicochemical properties of the tested wood samples was found.Wood characteristics strongly correlated with soil moisture.A significantly higher mass decline of wood samples was recorded on the reference study plots,which were characterized by more stable moisture conditions.Poorer decomposition of wood in the gaps regardless of the species is related to lower moisture.The wood species covered by the study differed in the decomposition rate.Spruce wood samples were characterized by a significantly higher decomposition rate compared to beech wood samples.Our research has confirmed that disturbances that lead to the formation of gaps have a direct impact on the decomposition process of deadwood.

The Oxyalkylation of Hydrophilic Black Alder Bark Extractives with Propylene Carbonate with a Focus on Green Polyols Synthesis

The isolated hydrophilic black alder(Alnus glutinosa)bark extractives were characterized in terms of component and functional composition and converted at 150℃-170℃ into liquid green polyols using solvent-free and lowtoxic base-catalyzed modification with propylene carbonate(PC).FTIR spectroscopy,HP-LC,GC,GPC,and wet chemistry methods were used to characterize the starting constituents,intermediate and final products of the reaction and to monitor the different pathways of PC conversion.The reaction of extractives as well as the model compounds,including catechol,xylose,PEG 400,and benzoic acid,with PC indicated the ability of OH groups of different origins present in the extractives to condense with equivalent amounts of PC.The polyols obtained consist of a copolymer fraction with one oxypropyl unit grafted per OH functionality of extractive components on average and oligo oxypropyl diols with a small number of carbonate linkages in the chain,obtained as a result of remaining PC homopolymerization.The domination of the oxypropylation mechanism vs.transcarbonation for PC ring opening was observed for both copolymerization and homopolymerization processes,making the process of oxypropylation with PC similar to that of conventional oxypropylation.At optimal reaction conditions,including a PC/OH ratio of 3.0 and a 24-h duration at 150°C,uniform polyols with low viscosity of~900 mPa·s^(-1),a biomass content of~27%,and an OHV of~500 mg KOH·g^(-1) were obtained.Increasing the temperature of modification allows shortening the process but drastically increases the polyol viscosity.At fixed temperature values,increasing the PC/OH ratio not only decreases the biomass content but also strongly prolongs the processing.The significantly increased duration of the process using PC as an alternative oxyalkylation agent compared to that of oxyalkylation with propylene oxide is a reasonable trade-off for using a safer and more environmentally friendly technology.

Matrix Assisted Laser Desorption Ionization Time of Flight(MALDI-TOF)-Mass Spectrometry and^(13)C-NMR-Identified New Compounds in Paraberlinia bifoliolata(Ekop-Beli)Bark Tannins

Extracts of plant origin,particularly tannins,are attracting growing interest for the sustainable development of materials in the industrial sector.The discovery of new tannins is therefore necessary.The aim of this work was to contribute to the understanding of the properties of Paraberlinia bifoliolata tannin by Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectroscopy MALDI-TOF/MS and Carbon 13 Nuclear Magnetic Resonance(13C NMR).The chemical composition of tannin extracted from Paraberlinia bifoliolata bark was determined,as was the mechanical strength of the resin hardened with Acacia nilotica extracts.Yield by successive water extraction was 35%.MALDI-TOF/MS analysis revealed the presence of three new compounds in this tannin,previously unknown in this family of extracts.These are 3-hydroxyproline acid,N-methyl-4-hydroxypipecolic acid and N-methyl-5-dihydroxypipecolic acid.The identification of the above molecules means that this tannin can be used for industrial applications,as a resin in the manufacture of particleboard and in the formulation of green corrosion inhibitors.This information is reinforced by 13C NMR spectrometry,which indicates the presence of several polyflavonoid units,confirming the condensed nature of the tannin.Thermomechanical analysis of the resin formed by the purified tannin of Paraberlinia bifoliolata to which a vegetal biohardener has been added provided a Modulus of Elasticity(MOE)value of 4840 MPa at 150℃,confirming its possible use as a binder resin in the manufacture of wood panels as well as for the formulation of a corrosion inhibitor.

Patterns and impacts of an unprecedented outbreak of bark beetles in Central Europe: A glimpse into the future?

Natural disturbances have significantly intensified across European forests,with bark beetle outbreaks being the most rapidly escalating disturbance type.Since 2018,the Czech Republic(Central Europe)has become a Europe's disturbance epicentre due to the unprecedented outbreak of spruce bark beetle Ips typographus in the forests dominated by Norway spruce Picea abies.Here we provide novel insights into the impacts and dynamics of this disturbance from 2016 to 2022.The investigation is based on annual forest change maps developed by the classification of optical and Synthetic Aperture Radar satellite imagery.We identified seven major outbreak foci across the country,where the outbreaks culminated between 2018 and 2021.Most of the outbreak waves exhibited a symmetric shape,characterized by a three-year build-up phase,a single culmination year,and the subsequent decline.The substantial proportion of spruce remaining in the outbreak areas after the culmination point implies that resource depletion is an improbable cause for the outbreak's retreat.In the year of retreat,the proportion of spruce in the forest ranged between 26%and 36%in most of the outbreak areas.The disturbance dynamics manifested a transition from the emergence of new tree mortality spots in the early outbreak phase to their short-range expansion,suggesting density-dependent changes in bark beetle dispersal during the studied period.The core disturbance zone,pinpointed in 2022,covered an area of 9,000 km^(2) and experienced a 38%loss in forest cover.Within this area,forest fragmentation increased significantly,leading to a greater forest patch complexity and reduced connectivity among the patches.The presented findings can serve as a glimpse into the future for other European regions,revealing the potential impacts of natural disturbances amplified by climate change.

Lipophilic extractives of the inner and outer barks from six different Pinus species grown in Indonesia

The chemical compositions of the dichloromethane extracts of inner and outer barks from six Pinus species（P.elliotii,P.oocarpa,P.caribeae,P.merkusii,P.montezumae,and P.insularis） grown in Indonesia were investigated by GC and GC–MS.Generally,the amounts of extractive contents were higher in the inner bark than in the outer bark except for P.merksuii.Fatty acids,monoterpenes,sesquiterpenes,resin acids,triterpenoids,and steroids were detected and quantified.Inner and outer barks differed not only in content of these compounds but also in their composition.Fatty acids and alcohols were the major classes of lipophilic compounds in the outer bark of P.caribeae, P.insularis,and P.montezumae.Steroids and triterpenoids were the dominant compounds identified in the inner bark of P.elliotii,P.insularis,and P.merkusii.Resin acids were the most abundant group in the inner bark of P.oocarpa whereas monoterpenes and sesquiterpenes were recorded in minor quantities in both bark layers of all species.

基于听觉掩蔽效应和Bark子波变换的语音增强

提出了一种适用于低信噪比下的提高语音的听觉效果的语音增强方法。该方法在谱减法的基础上有两个特点:首先减参数是根据人耳听觉掩蔽效应提出的且是自适应的;其次采用了与人耳听觉系统特性更为适应的Bark子波变换方法对增强前后的语音进行分析。对该算法进行了客观和主观测试,结果表明:与谱减法相比对低信噪比的语音信号,(1)能更好地抑制残留噪声和背景噪声,(2)增强后的语音具有更好的清晰度和可懂度。

一种基于Bark域能量分布的噪声分类方法

对不同种类噪声的分类处理,可以提高噪声环境下语音信号处理的性能。为了能够准确地区分各类噪声,提出了一种基于Bark域噪声能量分布特性的噪声分类方法。通过将噪声能量从均匀时频空间映射到Bark空间,构造了一个能够有效区分各种噪声的22维特征向量,并使用支持向量机(SVM)进行模型训练和噪声分类。实验结果表明:所提出的噪声分类方法具有非常高的分类准确率,对用于实验的两种噪声数据集的平均分类准确率分别为99.50%和93.44%。

基于Bark域噪声估计及掩蔽效应的语音增强

针对非平稳环境下噪声估计和语音增强性能降低的特点,提出一种基于Bark域的快速自适应噪声谱估计算法。它基于听觉模型,将带噪信号变换到Bark域,并在Bark域内实现基于人耳掩蔽的语音增强。仿真实验表明该算法能充分利用Bark带内频带间的相关性,跟踪快变的背景噪声,提高语音增强性能,减少运算量和复杂度。

基于Fisher比的Bark小波包变换的语音特征提取算法

为解决MFCC特征参数在噪声环境中识别率低的问题,提出一种基于Fisher比的Bark小波包变换特征提取算法.首先采用小波包变换构造Bark滤波器代替三角形的Mel滤波器.其次采用Fisher对Bark滤波后的特征参数进行选择,去除大量干扰信息,节省特征匹配的时间.仿真实验表明,该算法明显提高系统的识别率和鲁棒性.

基于BARK子波变换的语音增强方法研究

在Bark子波的构造的基础上,提出一种改进的Bark子波变换构造方法,即直接由临界带中心频率确定Bark子波的中心频率,保证了其通带和临界带的对应一致性,并与人耳的听觉系统十分吻合。采用Bark子波对带噪语音进行分解,在语音信号的子带层次上用一种类似于软阈值的无穷阶可导的函数进行阈值处理,并应用谱减法进行二次增强。仿真实验表明,构建Bark子波与增强算法使信噪比和PESQ得分都有较大提高,特别是在信噪比较高时,语音具有很好的清晰度和可懂度。

Acidity and conductivity of Pinus massoniana bark as indicators to atmospheric acid deposition in Guangdong, China

Barks of Pinus massoniana collected from two polluted sites, Qujiang and Xiqiaoshan, and from the relatively clean site Dinghushan were used to evaluate the pollution indication by the determination of their acidity and conductivity. The acidity of the inner and outer barks from the polluted sites was significantly higher than those from the clean site, suggesting that the acidity of the bark occurred in concurrent with the air pollution. The significant lower pH values of the outer bark than the inner bark collected from all sites indicated that the outer bark was more sensitive than the inner bark in response to acid pollution, implying that the outer bark is more preferable when used as indication of atmospheric acid pollution. The conductivities of the inner barks differed significantly among the three sites, with higher values at the clean site. However, the significant differences were not observed among these sites. Furthermore, the pH values for the inner and outer barks were not correlated with the conductivity, which did not coincide with some other studies.

基于Bark子波变换和RAS-MFCC特征的语音识别系统研究

提出了一种适用于低信噪比下的语音识别算法。该算法在前端利用人耳听觉掩蔽效应进行语音增强,然后提取一种在不需要噪声先验知识,能避免大量计算的情况下能较好地消除系统加性噪声的自相关MFCC(RAS-MFCC)参数,作为语音特征参数进行识别。

基于小波包Bark子带方差的端点检测算法

传统的端点检测方法大多数抗噪性不好,基于能量和短时过零率的双参数双门限端点检测在静音状态下效果较好,但是在噪声环境中性能下降.针对这个问题,使用小波包变换把信号分解成17个Bark子带,求出平均方差值,然后采用单参数双门限方法进行端点检测.实验证明,即使在-2dB的噪声环境下,该方法仍然能取得较好的端点检测效果.

基于Bark小波的语音端点检测算法

为提高噪声环境下端点检测算法的性能,提出一种基于Bark小波变换的语音端点检测算法。在Bark小波变换的非线性映射中引入伸缩尺度参数,提取不同子带上信号的小波变换系数,利用Bark小波的奇异性构造端点检测参数,并通过仿真验证得到有效的阈值选择规则。实验结果表明,与传统的短时能量法和倒谱距离测度法相比,该算法的检测准确率明显提高,具有较强的噪声鲁棒性。

一种Bark子波变换的电子耳蜗语音增强算法

提出了一种Bark子波变换的电子耳蜗语音增强算法。该算法首先引入与人耳听觉系统更为适应的Bark子波变换来进行电子耳蜗CIS语音信号处理,然后在每个Bark通道中利用非线性谱减法对其进行语音增强,谱减法的参数由人耳隐蔽阈值来控制。结果表明:即使在低信噪比的情况下,信噪比也能提高16dB左右,合成的语音对于电子耳蜗使用者具有较好的清晰度和可懂度。

基于Bark子波变换的MFCC特征提取

为提高低信噪比环境下语音的鲁棒性,提出一种改进的Mel频率倒谱系数(MFCC)特征提取方法。在传统MFCC特征提取的基础上,引入更适应人耳听觉系统的Bark子波变换,在快速傅里叶变换之前对语音进行预处理,并在MFCC提取方法中代替离散余弦变换;在语音预处理阶段,利用改进的Lanczos窗函数抑制旁瓣以提高语音鲁棒性。实验表明,与传统MFCC方法相比,在噪声环境下,改进方法具有更高的说话人识别率。

FrFT-Bark域特征提取与CNN残差收缩网络心音分类算法

为充分挖掘心音信号的生理、病理信息,提高心音自动分类的准确率,提出一种不依赖于分割和去噪的心音自动分类新算法.首先提取心音信号Bark域分数傅里叶变换的时频特征,然后将深度残差收缩网络引入卷积神经网络中构建新的分类模型,该模型能够自动去除与当前任务无关的特征信息,提高模型预测的准确率及稳定性.研究所用心音样本5000例,其中1000例用于测试.实验结果表明,提出算法的准确率、灵敏度、特异度分别为0.925、0.902、0.948,F1值为0.923.该方法整体性能较以往方法有明显提升,具有较强的鲁棒性和泛化能力,有望应用于先心病的临床筛查.

Protective effects of Foeniculum vulgare root bark extract against carbon tetrachloride-induced hepatic fibrosis in mice

AIM To investigate the protective effects of Foeniculum vulgare root bark (FVRB), a traditional Uyghur medicine, against carbon tetrachloride (CCl4)-induced hepatic fibrosis in mice. METHODS Mice were randomly divided into eight groups (n = 20 each). Except for the normal control group, mice in the rest groups were intraperitoneally injected (i.p.) with 0.1% CCl4-olive oil mixture at 10 mL/kg twice a week to induce liver fibrosis. After 4 wk, mice were treated concurrently with the 70% ethanol extract of FVRB (88, 176, 352 and 704 mg/kg, respectively) daily by oral gavage for 4 wk to evaluate its protective effects. Serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), triglyceride (TG), hexadecenoic acid (HA), laminin (LN), glutathione (GSH), superoxide dismutase (SOD), and malondialdehyde (MDA) in liver tissues were measured. Hematoxylin-eosin (H and E) staining and Masson trichrome (MT) staining were performed to assess histopathological changes in the liver. The expression of transforming growth factor beta 1 (TGF-beta 1), matrix metalloprotein 9 (MMP-9) and metallopeptidase inhibitor 1 (TIMP-1) was detected by immunohistochemical analysis. Additionally, TGF-beta 1 and alpha-smooth muscle actin (alpha-SMA) protein expression was measured by Western blot. RESULTS A significant reduction in serum levels of AST, ALT, TG, HA and LN was observed in the FVRB-treated groups, suggesting that FVRB displayed hepatoprotective effects. Also, the depletion of GSH, SOD, and MDA accumulation in liver tissues was suppressed by FVRB. The expression of TGF-beta 1, MMP-9 and TIMP-1 determined by immunohistochemistry was markedly reduced in a dose-dependent manner by FVRB treatment. Furthermore, protective effects of FVRB against CCl4-induced liver injury were confirmed by histopathological studies. Protein expression of TGF-beta 1 and alpha-SMA detected by Western blot was decreased by FVRB treatment. CONCLUSION Our results indicate that FVRB may be a promising agent against hepatic fibrosis and its possible mechanisms are inhibiting lipid peroxidation and reducing collagen formation in liver tissue of liver fibrosis mice.

Inhibition of Ehrlich ascites carcinoma by Manilkara zapota L.stem bark in Swiss albino mice

Objective:To evaluate the antitumor activity of Manilkara zapota(M.zapota) L.stem bark against Ehrlich ascites carcinoma(EAC) in Swiss albino mice.Methods:The in vivo antitumour activity of the ethyl acetate extract of stem bark of M.zapota L.(EASM) was evaluated at 50,100 and 200 mg/kg bw against EAC using mean survival time.After administration of the extract of M.zapota,viable EAC cell count and body weight in the EAC tumour hosts were observed.The animal was also observed for improvement in the haematological parameters(e.g.,heamoglobin content,red and white blood cells count and differential cell count) after EASM treatment. Results:Intraperitoneal administration of EASM reduced viable EAC cells,increased the survival lime,and restored altered haematological parameters.Significant efficacy was observed for EASM at 100 mg/kg dose(P<0.05).Conclusions:It can be concluded that the elhyl acetate extract of stem bark of M.zapota L.possesses significant antitumour activity.