Research on the Bending Impact Resistance and Transverse Fracture Characteristics of Bamboo under the Action of Falling Weight

Drop weight impact tester was used to accurately measure the bending impact resistance of various parts of Phyllostachys edulis,commonly known as moso bamboo,with a growth cycle of 3–8 years.Cellulose crystallinity in the bottom(B),middle(M)and top(T)of bamboo at different ages was calculated using peak height analysis in X-ray diffraction.Heatmap of Spearman correlation analysis was used to represent the correlation between chemical composition and impact mechanics.The breaking load(BL),fracture energy(FE)and impact deflection(ID)of 3–8-year-old bamboo were found to be in the range of~670–2120 N,~5.17–15.55 J,and~3.60–~17.76 mm,respectively.As the growth period of bamboo rises,the cellulose crystallinity at the B and T decreases first and then increases,while that for the M increases first and then remains stable.Similarly,the bending impact performance of bamboo was found to become stable with its growth and age.The flexural impact and toughness of the 4-year-old bamboo base material were better than other specimens.The enhancement in the bending impact properties of bamboo at different growth periods was influenced by the lignin content,while the value of FE was mainly positively correlated with ash,cold and hot water extracts and benzyl alcohol content.However the content of holocellulose and pentosan,air-dry density and,base density negatively influenced the FE.With the change in the height of the bamboo,the correlation between its impact mechanical properties and chemical composition gradually decreased.This study provides data support and theoretical basis for the age-appropriate thinning and application of moso bamboo.

Effects of Hydrothermal Environment on the Deformation of the Thin Bamboo Bundle Veneer Laminated Composites

To overcome warping in thin bamboo bundle veneer laminated composites(TBLC),their hydrothermal deformation characteristics were systematically investigated in this study.It was found that TBLCs accelerated the release of internal stress in the thickness direction in a hydrothermal environment,which increased their warpage.TBLCs showed increased warpage in the width and diagonal directions upon increasing the temperature.The warpage of Type E increased by 155.88%and 66.67%in the width and diagonal directions,respectively,when the temperature increased from 25
C to 100
C.The symmetrical TBLC with cross-lay-up and odd layers displayed better hydrothermal stability.We revealed that the deformation of the TBLCs could be regulated under the synergistic effect of water and temperature.These results provide a scientific basis for improving the uniformity of bamboo bundle composite materials and for developing thin bamboo bundle fiber composite materials with designable structures and controllable performance.

Mechanical and Rheological Properties of Bamboo Pulp Fiber Reinforced High Density Polyethylene Composites:Influence of Nano CaCO_(3)Treatment and Manufacturing Process with Different Pressure Ratings

In order to investigate the effect of the relative motion of nano CaCO_(3)reinforced bamboo pulp fiber(BPF)/HDPE composite components on the mechanical performance,a comparative study was performed.BPF was treated by nano CaCO_(3)blending(BM)and impregnation modification(IM)technology.The composites were produced using hot press(HPMP),extrusion(EMP)and injection molding process(IMP).The physical morphology of BPF was similar at different manufacturing processes.Compared to the samples manufactured by HPMP,a decrease in the(specific)flexural strength of BPF/HDPE composites and an increase in those of composites treated by nano CaCO_(3)manufactured by EMP and IMP were observed.The injection molded composites exhibited the best values in the(specific)impact strength,(specific)tensile properties.IM had a greater effect on the rheological behavior of the composites than BM,and nano CaCO_(3)treatment most effectively affected the performance of the extrusion molded composites.

Review on Bond Properties between Wood and Fiber Reinforced Polymer

Retrofitting of existing ancient and modern timber structures has been an important project recently.And it triggers a need of excellent strengthening methods,so does the strengthening of newly built architecture.Traditional strengthening methods have shortcomings such as high costing and destroying the aesthetic of the structure,many of which can be overcome by means of using fiber reinforced polymer(FRP)composites.However,the behavior of FRP-towood systems has yet to be thoroughly researched compared with their FRP-toconcrete or FRP-to-steel counterparts.As FRP retrofitting and strengthening timber structures has a promising future,better understanding of their failure modes will enable more precise designs balancing safety and cost.Three of the most common FRP-to-wood systems in the literature are discussed in this paper,namely,the externally bonded reinforcement(EBR),the near-surface mounted(NSM)and the glued-in rods(GiR)techniques.Debonding of the FRP from the substrate is one of the most common failure modes,which exhibits the significance of the interface bond between FRP laminates and wood.Hence,bond properties and behavior of FRP-to-wood composite systems are described,parameters influencing the composite action are summarized in this paper,previous works on the bond interface of FRP and timber element are reviewed and future topics are also suggested.This work can provide a reference for future research and engineering applications.

Management scheme influence and nitrogen addition effects on soil CO_(2),CH_(4),and N_(2)O fluxes in a Moso bamboo plantation

Background:It is still not clear whether the effects of N deposition on soil greenhouse gas(GHG)emissions are influenced by plantation management schemes.A field experiment was conducted to investigate the effects of conventional management(CM)versus intensive management(IM),in combination with simulated N deposition levels of control(ambient N deposition),30 kg N·ha^(−1)·year^(−1)(N30,ambient+30 kg N·ha^(−1)·year^(−1)),60 kg N·ha^(−1)·year^(−1)(N60,ambient+60 kg N·ha^(−1)·year^(−1)),or 90 kg N·ha^(−1)·year^(−1)(N90,ambient+90 kg N·ha^(−1)·year^(−1))on soil CO_(2),CH_(4),and N_(2)O fluxes.For this,24 plots were set up in a Moso bamboo(Phyllostachys edulis)plantation from January 2013 to December 2015.Gas samples were collected monthly from January 2015 to December 2015.Results:Compared with CM,IM significantly increased soil CO_(2) emissions and their temperature sensitivity(Q_(10))but had no significant effects on soil CH_(4) uptake or N_(2)O emissions.In the CM plots,N30 and N60 significantly increased soil CO_(2) emissions,while N60 and N90 significantly increased soil N_(2)O emissions.In the IM plots,N30 and N60 significantly increased soil CO_(2) and N_(2)O emissions,while N60 and N90 significantly decreased soil CH_(4) uptake.Overall,in both CM and IM plots,N30 and N60 significantly increased global warming potentials,whereas N90 did not significantly affect global warming potential.However,N addition significantly decreased the Q_(10) value of soil CO_(2) emissions under IM but not under CM.Soil microbial biomass carbon was significantly and positively correlated with soil CO_(2) and N_(2)O emissions but significantly and negatively correlated with soil CH_(4) uptake.Conclusion:Our results indicate that management scheme effects should be considered when assessing the effect of atmospheric N deposition on GHG emissions in bamboo plantations.

Different mechanisms underlying divergent responses of autotrophic and heterotrophic respiration to long-term throughfall reduction in a warm-temperate oak forest

Background:There are many studies on disentangling the responses of autotrophic(AR)and heterotrophic(HR)respiration components of soil respiration(SR)to long-term drought,but few studies have focused on the mechanisms underlying its responses.Methods:To explore the impact of prolonged drought on AR and HR,we conducted the 2-year measurements on soil CO_(2) effluxes in the 7th and 8th year of manipulated throughfall reduction(TFR)in a warm-temperate oak forest.Results:Our results showed long-term TFR decreased HR,which was positively related to bacterial richness.More importantly,some bacterial taxa such as Novosphingobium and norank Acidimicrobiia,and fungal Leptobacillium were identified as major drivers of HR.In contrast,long-term TFR increased AR due to the increased fine root biomass and production.The increased AR accompanied by decreased HR appeared to counteract each other,and subsequently resulted in the unchanged SR under the TFR.Conclusions:Our study shows that HR and AR respond in the opposite directions to long-term TFR.Soil microorganisms and fine roots account for the respective mechanisms underlying the divergent responses of HR and AR to long-term TFR.This highlights the contrasting responses of AR and HR to prolonged drought should be taken into account when predicting soil CO_(2) effluxes under future droughts.

Preparation and Characterization of Natural Bamboo Fiber

In this study,natural bamboo fiber was prepared combining chemical pretreatment with mechanical disc refining,opening,and carding.An orthogonal experiment was designed based on four factors and three levels;thereafter,the manufacturing process was optimized.The length,diameter,tensile strength,and elastic modulus of the bamboo fiber were determined,and the crystallinity and morphology of the fiber were analyzed using X-ray diffraction(XRD)and scanning electron microscopy(SEM).The results showed that the optimum parameters for the chemical pretreatment were a cooking temperature of 130℃,heating time of 2 h,NaOH dosage of 2%,and Na2SO3 dosage of 10%.The cooking yield of bamboo chips was 89.5%,and the carding yield of natural bamboo fiber was 43.0% under the optimum conditions.The length,diameter,tensile strength,and elastic modulus of the obtained fiber were 36.71 mm,0.285 mm,407 MPa,and 27.7 GPa,respectively.XRD analysis and SEM observations showed that the technology used in this study can produce bright and compact natural bamboo fibers with high crystallinity.

Physicochemical and Morphological Variation of Bamboo Cell Wall During Hydrothermal Pretreatment

Pretreatment is important for achieving high-value utilization of biomass.This study is conducted to evaluate the destruction of the Moso bamboo cell wall via hydrothermal pretreatment at different temperatures and pH values.Compositional and morphological analyses and subsequent enzymatic hydrolysis of the solid fractions indicate that the destruction of the cell wall,instead of the degradation or removal of hemicellulose and lignin,or the configuration transition of the cellulose crystal structure,is the most critical aspect for improving bioconversion efficiency.Although only an 8%-10%weight loss is incurred and similar crystalline indexes are achieved after mild hydrothermal treatments,the recovery of glucose is doubled,whereas the recovery of xylose from pretreated samples is approximately 35%.

A Mini-review for the Application of Bacterial Cellulose-based Composites

Countries are duly focusing more on biomass resources because of the increasing oil crisis.Owing to their excellent properties,such as natural characteristics,good mechanical performance,and outstanding chemical properties,cellulose-based materials are highly valued as promising bioderived nanomaterials,especially bacterial cellulose(BC).The main advantage lies in eliminating the problem of removing lignin and hemicellulose from woody cellulose.Moreover,the use of BC reduces the consumption of wood,the excessive use of which aggravates global warming.Herein,we summarize the applications of BC composites in filter,medical,and conductive materials,and other fields.This review contributes to further expand the applications of this renewable polymer.

Mechanism of nitrogen loss driven by soil and water erosion in water source areas

Nitrogen(N)present in drinking water as dissolved nitrates can directly affect people’s health,making it important to control N pollution in water source areas.N pollution caused by agricultural fertilizers can be controlled by reducing the amount of fertilizer applied,but pollution caused by soil and water erosion in hilly areas can only be controlled by conservation forests.The catchment area around Fushi Reservoir was selected as a test site and mechanisms of N loss from a vertical spatial perspective through field observations were determined.The main N losses occurred from June to September,accounting for 85.9-95.9%of the annual loss,with the losses in June and July accounting for 46.0%of the total,and in August and September for 41.9%.The N leakage from the water source area was effectively reduced by 38.2%through the optimization of the stand structure of the conservation forests.Establishing well-structured forests for water conservation is crucial to ensure the security of drinking water.This preliminary research lays the foundation for revealing then loss mechanisms in water source areas and improving the control of non-point source pollution in these areas.

Habitats shape root-associated fungal and bacterial communities of Minjiang fir saplings

Root-associated microbes play an essentialrole in mediating plant growth,health,and habitat adaptability.However,it is unknown which microbial taxa help develop host fitness and how habitats shape root-associated microbial assembly patterns.As an endemic species of subalpine forests in western Sichuan,China,Minjiang fir(Abies fargesii var.faxoniana)is dominant on cold-shaded northwestern slopes while absent on warm sunlit southwestern slopes.In this study,fungal and bacterial communities were investigated in three spatial compartments(endosphere,rhizosphere,and bulk soil)associated with Minjiang fir saplings on a cold-shaded northwestern slope and a warm sunlit southwestern slope.Habitats differentiated the microbial communities regardless of the spatial compartment and microbial taxa.Slope aspect variations caused shifts in root-associated(rhizosphere and endosphere)microbial compositions.Compared with the southwestern slope,the cold-shaded northwestern slope harbored a higher abundance of the growth-promoting bacteria Burkholderia and ectomycorrhizal fungi Cortinarius and Piloderma.The slope aspect had stronger effects on fungal diversity than bacterial diversity,with higher fungal endemism and lower bacterial endemism.Slope aspect variations were the dominant drivers of root-associated microbial communities,with lower contribution by soil properties and higher contribution by plant traits on the northwestern slope.Findings from this study could improve the understanding of plant habitat adaptability from the perspective of microbial community assembly.It is suggested that forest management should consider root-associated microbiomes for enhancing species fitness and habitat adaptability.

Mechanical Behavior of Bamboo,and Its Biomimetic Composites and Structural Members:A Systematic Review

Bamboo is a typical biological material widely growing in nature with excellent physical and mechanical properties.It is lightweight with high strength and toughness.The naturally optimized bamboo structure,which has inspired global material scientists and engineers for decades,is significantly important for the bionic design of novel structural materials with ultra-light,ultra-strong,or ultra-tough and comprehensive properties.Typical literature on innovative composite materials and structural members inspired by bamboo are reviewed in this paper,and the research progress and prospects in this field are expounded in three parts.First,the structural characteristics of the bamboo wall layer along the thickness and height directions are described in terms of chemical composition,gradient structure,pore structure,and hollow structure with variable cross-section.Second,this paper summarizes the research progress on new composite materials and structural components by applying bamboo’s structural features from the perspective of sustainability,designability,and customization.Finally,given the limitations of current research,the biomimetic scientific research on bamboo’s structural characteristics is prospected from the interpretation of bamboo structure,new bamboo-like materials,and structural design optimization perspectives,providing a reference for future research on biomimetic aspects of biomass.

Effect of microenvironmental quantitative regulation on growth of Korean pine trees planted under secondary forest

Korean pine（Pinus koraiensis） and broadleaved mixed forest in Northeast China has been changed regressively into secondary forest with almost no conifers.Planting Korean pine trees under the canopy of secondary forest is a feasible approach for recovering Korean pine and broadleaved mixed forest.For establishing an effective growth promotion method for under-canopy planted young Korean pine trees,two stands were selected as the experiment plots,Stand A（planted in 1989） and Stand B（planted in 1982）,and an experiment of microenvironment regulation was conducted relying mainly on Opening degree（K=1,K=1.5,K=2,CK） in 2004.The results were shown that the adjustment had promoted growth of diameter and height of Korean pine planted in Stand A and Stand B,and had a significant influence on the growth rate of basal diameter,diameter at breast height and height in the two growth stands.The four years periodic increment of mean diameter and height of Korean pine planted in 1989 and in 1982 after regulation in K=1 level were 63.4%（D0） and 82.7%（H）,64.8%（D1.3） and 69.7%（H） higher than that of control respectively.Quantitative regulation had significant influence on specific leaf area of Korean pine planted in 1989,and the current year specific leaf area（SLA） was lager than perennial year SLA.Quality indexes of natural pruning capacity,normal form quotient and crown size was not significantly changed but shown a positive tendency.The regulation scheme of Opening degree K=1 might be proper for adjusting the microenvironment of Korean pine trees planted under the canopy of secondary forest when the Korean pine trees were in the growth period of 15 to 26 years old in the experiment region.

XPS and FTIR studies of fungus-stained Daemonorops margaritae

We explored the discoloration of rattan cane using X-ray photoelectron spectroscopy(XPS) and Fourier transform infrared spectroscopy(FTIR). XPS analysis showed that after the cane was stained by Lasiodiplodia theobromae, carbon and oxygen elements and the ratio of oxygen to carbon decreased. Considering atomic binding,C_1 and C_4 contents increased, while C_2 and C_3 contents decreased, and the ratio of O_2 to O_1 decreased sharply. The relative contents of lignin, cellulose and polysaccharides increased and new substances with low O_2/O_1 ratio occurred. FTIR analysis showed that the absorption peaks of O–H at 3346 cm^(-1), aliphatic C–H at 2921, 2853 and1464 cm^(-1), and C=O at 1723 cm^(-1), were characteristic peaks of fungal melanin intensified, indicating that cane discoloration was primarily caused by fungal melanin. The absorption peaks characterizing cellulose and lignin like polysaccharides at 800 cm^(-1), C–H at 1374 cm^(-1), C–O at1058 and 1038 cm^(-1), phenolic hydroxyl at 1245 cm^(-1),aromatic ether bonds at 1270 cm^(-1), carbon skeleton at1608 cm^(-1) and benzene ring at 1500 cm^(-1) were enhanced since the fungus mainly consumed the extractives in cane cell lumens and the main composition content increased relatively. Regardless of the discoloration caused by natural fungi or inoculated fungi, the discoloring feature and composition changes were identical except that the fungusinoculated cane had more melanin.

Cross-classes domain inference with network sampling for natural resource inventory

There are two distinct types of domains,design-and cross-classes domains,with the former extensively studied under the topic of small-area estimation.In natural resource inventory,however,most classes listed in the condition tables of national inventory programs are characterized as cross-classes domains,such as vegetation type,productivity class,and age class.To date,challenges remain active for inventorying cross-classes domains because these domains are usually of unknown sampling frame and spatial distribution with the result that inference relies on population-level as opposed to domain-level sampling.Multiple challenges are noteworthy:(1)efficient sampling strategies are difficult to develop because of little priori information about the target domain;(2)domain inference relies on a sample designed for the population,so within-domain sample sizes could be too small to support a precise estimation;and(3)increasing sample size for the population does not ensure an increase to the domain,so actual sample size for a target domain remains highly uncertain,particularly for small domains.In this paper,we introduce a design-based generalized systematic adaptive cluster sampling(GSACS)for inventorying cross-classes domains.Design-unbiased Hansen-Hurwitz and Horvitz-Thompson estimators are derived for domain totals and compared within GSACS and with systematic sampling(SYS).Comprehensive Monte Carlo simulations show that(1)GSACS Hansen-Hurwitz and Horvitz-Thompson estimators are unbiased and equally efficient,whereas thelatter outperforms the former for supporting a sample of size one;(2)SYS is a special case of GSACS while the latter outperforms the former in terms of increased efficiency and reduced intensity;(3)GSACS Horvitz-Thompson variance estimator is design-unbiased for a single SYS sample;and(4)rules-ofthumb summarized with respect to sampling design and spatial effect improve precision.Because inventorying a mini domain is analogous to inventorying a rare variable,alternative network sampling procedures are also readily available for inventorying cross-classes domains.

Bamboo and rattan: Nature-based solutions for sustainable development

INTRODUCTION Bamboo and rattan are valuable resources that can be used as nature-based solutions to several pressing global challenges by contributing to poverty reduction,the development of green industries and trade,the adaptation and mitigation of climate change,and the preservation of the environment.Largely growing in less-developed regions of the tropics and subtropics,the two plant groups are welcomed by local communities as they provide a wide variety of ecofriendly,sustainable products,livelihood opportunities,and ecosystem services.

Mechanical properties of flax fibres treated by alkaline,enzyme and steam-heat

In recent years there has been interest in using flax fibres to produce composites because of a number of attributes, including low density, biodegradability and high mechanical properties. It was found that treatment of flax fibres may be required to improve the bond quality with a resin. These treatments also have an impact on the properties of the fibres themselves. The objective of this project was to evaluate the impact of three treatment methods on the mechanical properties of flax fibres. The three treatment methods were alkaline, enzyme and steam-heat. After treatment, flax fibres were tested in tension using a universal test machine. Results showed that tensile strength and Young's modulus of flax fibre can be enhanced significantly by the three treatment methods, compared with untreated flax fibres. Enzyme treatment was shown to be the best approach to improve mechanical properties of flax fibre than alkaline and steam-heat treatment.

Effective of Microwave-KOH Pretreatment on Enzymatic Hydrolysis of Bamboo

Bamboo, with its advantages of fast growth, short renovation, easy propagation and rich in cellulose and hemicellulose, is a potential feedstock for bioethanol or other biofuels production. The objective of this study was to examine the feasibility of microwave assistant KOH pretreatments to enhance enzymatic hydrolysis of bamboo. Pretreatment was carried out by immersing the bamboo in KOH (12% and 8% w/w bamboo) solutions and exposing the slurry to microwave radiation power of 400 W for 30min. Chemical composition of the pretreated substrates and spent liquor was analyzed. Pretreated substrates were enzymatic hydrolyzed, and glucose and xylose in the hydrolysate were analyzed. The results showed that the pretreated substrate with microwave assisted KOH had significantly higher sugar yield than the untreated samples. The fermentation inhibitors formic acid, furfural, HMF and levulinic acid were much lower than acid pretreatment reported.

光学法和力学法测定单根纤维接触角及相关性分析

采用光学法和力学法测定8种单根纤维与水的接触角,通过数据统计比较两种测试方法的显著性差异,并对其测定结果进行相关性分析。试验结果表明:所选用的测定方法均可适用于竹麻等细短纤维接触角的测定,两种测定方法不存在显著性差异(P>0.05),力学法和光学法测定结果相关系数为0.812,呈显著相关(P=0.002<0.05)。

圆竹家具设计探究

圆竹家具在我国有着悠久的历史,具有丰富的人文内蕴,然而由于圆竹自身特性,造型和生产等方面受到限制,使圆竹家具难以适应现代人多样化的审美需求和工业化生产要求。笔者结合现代设计理念,对圆竹家具的特点和构造形式进行了深入分析,提出现代圆竹设计可以在生产过程上借鉴现代家具标准化统一生产,在外观造型上脱离传统的家具结构,精简家具构件,并且充分利用竹材韧性好等性能优势,突出造型美和材质美以满足现代审美需求;在连接结构上参考新材料或其他材料家具结构,在设计内涵上突出民族文化,引起情感共鸣。旨在为圆竹家具设计与制造提供理论指导,使圆竹家具设计符合现代生产和制造要求,满足消费者对家具外观造型的审美,达到消费者对圆竹家具情感的追求。