A hierarchical ubiquitination-mediated regulatory module controls bamboo lignin biosynthesis.

The lignocellulosic feedstock of woody bamboo shows promising potential as an alternative to conventional wood, attributed to its excellent properties. The content and distribution of lignin serve as the foundation of these properties. While the regulation of lignin biosynthesis in bamboo has been extensively studied at the transcriptional level, its posttranslational control has remained poorly understood. This study provides a ubiquitinome dataset for moso bamboo (Phyllostachys edulis), identifying 13015 ubiquitinated sites in 4849 unique proteins. We further identified Kelch repeat F-boxprotein 9 (PeKFB9) that plays a negative role in lignin biosynthesis. Heterologous expression of PeKFB9 resulted in reduced accumulation of lignin and decreased phenylalanine ammonia-lyase (PAL) activities. Both in vitro and in vivo assays identified interaction between PeKFB9 and PePAL10. Further examination revealed that SCFPeKFB9 mediated the ubiquitination and degradation of PePAL10 via the 26S proteasome pathway. Moreover, PebZIP28667 could bind to the PePAL10 promoter to significantly inhibit its transcription, and ubiquitination of PebZIP28667 weakened this inhibition. Collectively, our findings reveal a PeKFB9-PePAL10/PebZIP28667-PePAL10 module that acts as a negative regulator of lignin biosynthesis. This study advances our understanding of posttranslational regulation in plant lignification, which will facilitate the improvement of the properties of bamboo wood and the breeding of varieties.

Parallel sites implicate functional convergence of the hearing gene prestin among echolocating mammals.

Echolocation is a sensory system whereby certain mammals navigate and forage using sound waves, usually in environments where visibility is limited. Curiously, echolocation has evolved independently in bats and whales, which occupy entirely different environments. Based on this phenotypic convergence, recent studies identified several echolocation-related genes with parallel sites at the protein sequence level among different echolocating mammals, and among these, prestin seems the most promising. Although previous studies analyzed the evolutionary mechanism of prestin, the functional roles of the parallel sites in the evolution of mammalian echolocation are not clear. By functional assays, we show that a key parameter of prestin function, 1/α, is increased in all echolocating mammals and that the N7T parallel substitution accounted for this functional convergence. Moreover, another parameter, V1/2, was shifted toward the depolarization direction in a toothed whale, the bottlenose dolphin (Tursiops truncatus) and a constant-frequency (CF) bat, the Stoliczka's trident bat (Aselliscus stoliczkanus). The parallel site of I384T between toothed whales and CF bats was responsible for this functional convergence. Furthermore, the two parameters (1/α and V1/2) were correlated with mammalian high-frequency hearing, suggesting that the convergent changes of the prestin function in echolocating mammals may play important roles in mammalian echolocation. To our knowledge, these findings present the functional patterns of echolocation-related genes in echolocating mammals for the first time and rigorously demonstrate adaptive parallel evolution at the protein sequence level, paving the way to insights into the molecular mechanism underlying mammalian echolocation.

Cellulose structure and lignin distribution in normal and compression wood of the Maidenhair tree (Ginkgo biloba L.).

We studied in detail the mean microfibril angle and the width of cellulose crystals from the pith to the bark of a 15-year-old Maidenhair tree (Ginkgo biloba L.). The orientation of cellulose microfibrils with respect to the cell axis and the width and length of cellulose crystallites were determined using X-ray diffraction. Raman microscopy was used to compare the lignin distribution in the cell wall of normal/opposite and compression wood, which was found near the pith. Ginkgo biloba showed a relatively large mean microfibril angle, varying between 19° and 39° in the S2 layer, and the average width of cellulose crystallites was 3.1-3.2 nm. Mild compression wood without any intercellular spaces or helical cavities was observed near the pith. Slit-like bordered pit openings and a heavily lignified S2L layer confirmed the presence of compression wood. Ginkgo biloba showed typical features present in the juvenile wood of conifers. The microfibril angle remained large over the 14 annual rings. The entire stem disc, with a diameter of 18 cm, was considered to consist of juvenile wood. The properties of juvenile and compression wood as well as the cellulose orientation and crystalline width indicate that the wood formation of G. biloba is similar to that of modern conifers.

Healthy lifestyle decreases the risk of the first incidence of non-communicable chronic disease and its progression to multimorbidity and its mediating roles of metabolic components: a prospective cohort study in China.

OBJECTIVES: To identify the influence of healthy lifestyles on the incidence of the first NCD (FNCD), multiple chronic conditions (MCCs), and the progression from FNCD to MCCs. DESIGN: cohort study. SETTING: Zhejiang, China PARTICIPANTS: 10566 subjects (55.5 ± 13.5 years, 43.1% male) free of NCDs at baseline from the Zhejiang Metabolic Syndrome prospective cohort. MEASUREMENTS: Healthy lifestyle score (HLS) was developed by 6 common healthy lifestyle factors as smoking, alcohol drinking, physical activity, body mass index (BMI) and waist-to-hip ratio (WHR). Healthy lifestyle data and metabolic biomarkers collected via a face-to-face questionnaire-based interview, clinical health examination and routine biochemical determination. Biochemical variables were determined using biochemical auto-analyzer. Participants were stratified into four group based on the levels of HLS as ≤2, 3, 4 and ≥5. Multiple Cox proportional hazards model was applied to examine the relationship between HLS and the risk of FNCD, MCCs and the progression from FNCD to MCCs. The population-attributable fractions (PAF) were used to assess the attributable role of HLS. Mediating effect was examined by mediation package in R. RESULTS: After a median of 9.92 years of follow-up, 1572 participants (14.9%) developed FNCD, and 149 (1.4%) developed MCCs. In the fully adjusted model, the higher HLS group (≥5) was associated with lower risk of FNCD (HR = 0.68 and 95% CI: 0.56-0.82), MCCs (HR = 0.31 and 95%CI: 0.14-0.69); and the progression from FNCD to MCCs (HR = 0.39 and 95%CI: 0.18-0.85). Metabolic components (TC, TG, HDL-C, LDC-C, FPG, and UA) played the mediating roles with the proportion ranging from 5.02% to 22.2% for FNCD and 5.94% to 20.1% for MCCs. PAFs (95%CI) for poor adherence to the overall healthy lifestyle (HLS ≤ 3) were 17.5% (11.2%, 23.7%) for FNCD, 42.9% (23.4%, 61.0%) for MCCs, and 37.0% (15.5%, 56.3%) for the progression from FNCD to MCCs. CONCLUSIONS: High HLS decreases the risk of FNCD, MCCs, and the progression from FNCD to MCCs. These effects are partially mediated by metabolic components. Maintaining healthy lifestyles might reduce the disease burden of common chronic diseases.

Large-scale survey of gut microbiota associated with MHE Via 16S rRNA-based pyrosequencing.

OBJECTIVES: Elucidating the minimal hepatic encephalopathy (MHE)-associated gut microbiome may help in predicting and lowering the high risk for MHE in patients with cirrhosis. METHODS: Twenty-six MHE patients were recruited and screened from among those with liver cirrhosis without overt hepatic encephalopathy as defined by abnormality seen on two test modalities: number connection test part A and the digit symbol test. Using 26 MHE-matched normal relatives and 25 cirrhotic patients without MHE as controls, by means of 16S ribosomal RNA (rRNA)-based pyrosequencing, we examined and analyzed 241,622 bacterial 16S rDNA gene sequences from feces of 77 subjects. RESULTS: Using multiple comparative analyses, our results found the continuous overrepresentation of two bacterial families, Streptococcaceae and Veillonellaceae, in cirrhotic patients with and without MHE, compared with normal individuals. In addition, we also discovered an MHE-unique interplay pattern of gut microbiota largely influenced by the members of those two families. Following these findings, we further revealed that gut urease-containing bacteria Streptococcus salivarius was absent in the normal group but was present in cirrhotic patients with and without MHE. The abundance of S. salivarius was significantly higher in cirrhotic patients with MHE than in those without (P=0.030), and the change in the amount of this bacteria was positively correlated with ammonia accumulation (R=0.58, P=0.003) in cirrhotic patients with MHE but not in those without. CONCLUSIONS: Gut microbiota dysbiosis may be associated with the presence of MHE in cirrhotic patients, in particular with ammonia-increasing phenotype in MHE. Gut ammonia-increasing bacteria S. salivarius might be expected to be a potential biomarker of ammonia-lowering therapies in cirrhotic patients with MHE.

[Investigation of characteristic microstructures of adhesive interface in wood/bamboo composite material by synchrotron radiation X-ray phase contrast microscopy].

Third-generation synchrotron radiation X-ray phase-contrast microscopy(XPCM)can be used for obtaining image with edge enhancement, and achieve the high contrast imaging of low-Z materials with the spatial coherence peculiarity of X-rays. In the present paper, the characteristic microstructures of adhesive at the interface and their penetration in wood/bamboo composite material were investigated systematically by XPCM at Shanghai Synchrotron Radiation Facility (SSRF). And the effect of several processing techniques was analyzed for the adhesive penetration in wood/bamboo materials. The results show that the synchrotron radiation XPCM is expected to be one of the important precision detection methods for wood-based panels.

Healthy lifestyle scores associate with incidence of type 2 diabetes mediated by uric acid.

BACKGROUND: Whether and to what extent serum uric acid (SUA) mediates the association between combined lifestyle behaviors and type 2 diabetes mellitus (T2DM) remain unclear. This study aimed to investigate the role of SUA in the relationship between healthy lifestyle scores (HLS) and the incidence of T2DM. METHODS: This prospective study used data from Zhejiang Metabolic Syndrome cohort. A HLS (5-point scale including healthy waist circumference (WC), never smoking, high physical activity, healthy diet and moderate alcohol intake) was estimated in 13,919 participants, who had SUA at baseline examination in 2009-2014, and were followed-up to 2021-2022 to ascertain incident of T2DM. Cox proportional hazards models and mediation analysis were used to examine the associations between HLS, SUA and T2DM. RESULTS: We included 13,919 participants aged 18 years or older without diabetes at baseline (mean age 54.6 [SD 13.9] years, 58.7% female). During a median follow-up of 9.94 years, 645 cases of T2DM occurred. Compared with participants with a poor HLS, those with 4-5 low-risk lifestyle factors showed a 60% reduction in the risk of developing T2DM (adjusted HR, 0.40; 95% CI: 0.28-0.57). Further, the population-attributable risk percent (95% CI) of T2DM for poor adherence to the overall healthy lifestyle (< 4 low-risk factors) was 43.24% (30.02%, 56.46%). The HLS was inversely associated with SUA level. With per score increased in HLS, the beta (95% CI) of SUA (log transformed) was - 0.03 (- 0.03, - 0.02), and the odds ratio (95% CI) of hyperuricemia was 0.82 (0.77, 0.86). The relationship between the HLS and risk of T2DM was mediated by SUA with a 13.06% mediation effect. There was no significant combined effect of HLS and SUA on risk of T2DM (P = 0.097). CONCLUSIONS: The relationship between overall healthy lifestyle behaviors and T2DM was reconfirmed and the association appeared to be mediated by SUA. The mediation effect of baseline SUA was more pronounced among women who were below 60 years old.

Divergence and convergence of gut microbiomes of wild insect pollinators.

Pollination services provided by wild insect pollinators are critical to natural ecosystems and crops around the world. There is an increasing appreciation that the gut microbiota of these insects influences their health and consequently their services. However, pollinator gut microbiota studies have focused on well-described social bees, but rarely include other, more phylogenetically divergent insect pollinators. To expand our understanding, we explored the insect pollinator microbiomes across three insect orders through two DNA sequencing approaches. First, in an exploratory 16S amplicon sequencing analysis of taxonomic community assemblages, we found lineage-specific divergences of dominant microbial genera and microbiota community composition across divergent insect pollinator genera. However, we found no evidence for a strong broad-scale phylogenetic signal, which we see for community relatedness at finer scales. Subsequently, we utilized metagenomic shotgun sequencing to obtain metagenome-assembled genomes and assess the functionality of the microbiota from pollinating flies and social wasps. We uncover a novel gut microbe from pollinating flies in the family Orbaceae that is closely related to Gilliamella spp. from social bees but with divergent functions. We propose this novel species be named Candidatus Gilliamella eristali. Further metagenomes of dominant fly and wasp microbiome members suggest that they are largely not host-insect adapted and instead may be environmentally derived. Overall, this study suggests selective processes involving ecology or physiology, or neutral processes determining microbe colonization may predominate in the turnover of lineages in insect pollinators broadly, while evolution with hosts may occur only under certain circumstances and on smaller phylogenetic scales. IMPORTANCE Wild insect pollinators provide many key ecosystem services, and the microbes associated with these insect pollinators may influence their health. Therefore, understanding the diversity in microbiota structure and function, along with the potential mechanisms shaping the microbiota across diverse insect pollinators, is critical. Our study expands beyond existing knowledge of well-studied social bees, like honey bees, including members from other bee, wasp, butterfly, and fly pollinators. We infer ecological and evolutionary factors that may influence microbiome structure across diverse insect pollinator hosts and the functions that microbiota members may play. We highlight significant differentiation of microbiomes among diverse pollinators. Closer analysis suggests that dominant members may show varying levels of host association and functions, even in a comparison of closely related microbes found in bees and flies. This work suggests varied importance of ecological, physiological, and non-evolutionary filters in determining structure and function across largely divergent wild insect pollinator microbiomes.

[Distribution of lignin in Chinese fir branches determined by ultraviolet microspectrometer].

Distribution of lignin in the cell walls of Chinese fir branches emerged in the spring season were first studied by using ultraviolet microscope based on their cell microstructure observation and lignin qualitative measurement by the lightmicroscope and confocal laser scanning microscope. The results showed that the contents of lignin are inhomogeneously distributed in different micro-areas of the cell walls. The order of lignin concentrations is the cell corner>the middle lamellar>the secondary with the absorbance values of ultraviolet wave of 0.489, 0.307 and 0.278, respectively. The result of quantitative analysis consists with that of qualitative analysis. A new measurement method was proposed to study the distribution of lignin content in wood cell walls in CFhina.

The Long-Term Mechanical Properties of BS Perpendicular to the Grain.

As a modern bamboo composite with good mechanical properties, bamboo scrimber (BS) has achieved prominence in the sustainable architecture field. When used as a structural material, it is inevitably under continual tension perpendicular to the grain, therefore its mechanical response under long-term loading is significant for structural design. In this study, tensile tests were conducted on BS under short-term and long-term loads perpendicular to the grain. The duration of load (DOL) effect on BS perpendicular to grain and its creep effect were analyzed. Compared with BS parallel to the grain, the DOL effect on BS perpendicular to the grain was less severe, and the capacity for creep resistance was weaker. The threshold stress ratio and relative creep strain of BS perpendicular to the grain were 0.40 and 0.87, respectively. It was found that the DOL models and the viscoelastic model accurately predicted the DOL factor and creep strain. This study provides a scientific reference for the safe lifetime service of BS in practical engineering.

Diversified Shifts in the Cross Talk between Members of the Gut Microbiota and Development of Coronary Artery Diseases.

Coronary artery disease (CAD) is one of leading causes of mortality worldwide. Studies on roles that the gut microbiota plays in development of atherosclerosis or acute myocardial infarction (AMI) have been widely reported. However, the gut microbiota is affected by many factors, including age, body mass index (BMI), and hypertension, that lead to high CAD risk. However, the associations between gut microbiota and CAD development or other CAD risk factors remain unexplored. Here, we performed a 16S RNA gene sequencing analysis of 306 fecal samples collected from patients with mild coronary stenosis (MCS; n = 36), stable angina (SA; n = 91), unstable angina (UA; n = 48), and acute myocardial infarction (AMI; n = 66) and 65 non-CAD controls. Using a noise-corrected method based on principal-component analysis (PCA) and the random forest algorithm, we identified the interference with gut microbial profiling of multiple factors (including age, gender, BMI, and hypertension) that potentially contributed significantly to the development of CAD. After correction of noise interference from certain interfering factors, we found consistent indicator microbiota organisms (such as Vampirovibrio, Ruminococcus, and Eisenbergiella) associated with the presence of MCS, SA, and AMI. Establishment of a diagnostic model revealed better performance in early CAD than clinical indexes with indicator microbes. Furthermore, indicator microbes can improve the accuracy of clinical indexes for the diagnosis of AMI. Additionally, we found that the microbial indicators of AMI Sporobacter and Eisenbergiella showed consistent positive and negative correlations to the clinical indexes creatine kinase (CK) and hemoglobin (Hb), respectively. As a control indicator of AMI, Dorea was negatively correlated with CK but positively correlated with Hb. IMPORTANCE Our study discovered the effect of confounding factors on gut microbial variations and identified gut microbial indicators possibly associated with the CAD development after noise correction. Our discovered indicator microbes may have potential for diagnosis or therapy of cardiovascular disorders.

[Prediction of the lengths of fibers and vessels of rattans using near infrared spectroscopy].

The morphological characteristics of fibers and vessels of six rattan species in Southern China were investigated to study the feasibility of predicting the lengths of fibers and vessels of rattan species with application of analytical technologies of near infrared spectroscopy (NIR). The results showed that the average lengths of fibers and vessels of six rattan species were from 1 229 to 1 917 mm and from 1 035 to 2 129 mm, respectively. The models of length of fiber and vessel were constructed by combining partial least square (PLS) and full cross-validation, and a good correlation between the length of fibers and the spectrum transformed by the first derivative was found within the spectral range of 350 - 2 454 nm, and the correlation coefficient (r(c) and r(p)) and standard error (SEC and SEP ) of calibration model and prediction model are 0.98, 0.85 and 70, 178 respectively, while a good correlation between the length of vessels and the spectrum transformed by the first derivative was found within the spectral range of 350-2 500 nm, the correlation coefficient (r(c) and r(p)) and standard error (SEC and SEP) of calibration and prediction model is 0.97, 0.80 and 101, 261 respectively. Their model parameters showed that NIR spectroscopic technique can rapidly and accurately predict the lengths of fibers and vessels of the six rattan species.

Compressive Failure Mechanism of Structural Bamboo Scrimber.

Bamboo scrimber is one of the most popular engineering bamboo composites, owing to its excellent physical and mechanical properties. In order to investigate the influence of grain direction on the compression properties and failure mechanism of bamboo scrimber, the longitudinal, radial and tangential directions were selected. The results showed that the compressive load-displacement curves of bamboo scrimber in the longitudinal, tangential and radial directions contained elastic, yield and failure stages. The compressive strength and elastic modulus of the bamboo scrimber in the longitudinal direction were greater than those in the radial and tangential directions, and there were no significant differences between the radial and tangential specimens. The micro-fracture morphology shows that the parenchyma cells underwent brittle shear failure in all three directions, while the fiber failure of the longitudinal compressive specimens consisted of ductile fracture, and the tangential and radial compressive specimens exhibited brittle fracture. This is one of the reasons that the deformation of the specimens under longitudinal compression was greater than those under tangential and radial compression. The main failure mode of bamboo scrimber under longitudinal and radial compression was shear failure, and the main failure mode under tangential compression was interlayer separation failure. The reason for this difference was that during longitudinal and radial compression, the maximum strain occurred at the diagonal of the specimen, while during tangential compression, the maximum strain occurred at the bonding interface. This study can provide benefits for the rational design and safe application of bamboo scrimber in practical engineering.

Gluing Techniques on Bond Performance and Mechanical Properties of Cross-Laminated Timber (CLT) Made from Larix kaempferi.

Previous studies have proved that Larix kaempferi is a good material for preparing cross-laminated timber (CLT), but under bending shear stress, CLT made by Larix kaempferi is prone to the phenomenon of bonding face cracking, which seriously affects the shear performance of CLT. To solve this problem, this paper took Larix kaempferi as raw material, conducted experiments on the surface sanding conditions, gluing pressure and adhesive types of sawing timber, and explored the influence of these three factors on the bonding quality of CLT. The microscopic characteristics of the bonding layer were further studied. The results showed that for Larix kaempferi with a density of 0.68 g/cm3 used in this experiment, a high bonding pressure is required. Among the three cold curing adhesives selected in the experiment, emulsion polymer isocyanate (EPI) adhesive needs 1.5 MPa bonding pressure to ensure the bonding quality, while for polyurethane (PUR) and phenol resorcinol formaldehyde (PRF), 1.2 MPa can meet the need of adhesive pressure. This is concerned with the permeability of different adhesives under different pressures. The microscopic results of the bonding layer show that EPI adhesives have poor permeability, so it requires high bonding pressure. The influence of sanding surface of different sand-belt on block shear strength (BSS) and wood failure percentage (WFP) is not obvious, while the durability of bonding layer is better when sanding mesh number is 100. Hence, a high pressure should be used for CLT industrial production when the laminate density is higher, especially when the adhesive has poor permeability. Reasonable sanding surface treatment can be used in laminate surface treatment to improve the durability of CLT.

Analysis and Calculation of Stability Coefficients of Cross-Laminated Timber Axial Compression Member.

Cross-laminated timber (CLT) elements are becoming increasingly popular in multi-storey timber-based structures, which have long been built in many different countries. Various challenges are connected with constructions of this type. One such challenge is that of stabilizing the structure against vertical loads. However, the calculations of the stability bearing capacity of the CLT members in axial compression in the structural design remains unsolved in China. This study aims to determine the stability bearing capacity of the CLT members in axial compression and to propose the calculation method of the stability coefficient. First, the stability coefficient calculation theories in different national standards were analyzed, and then the stability bearing capacity of CLT elements with four slenderness ratios was investigated. Finally, based on the stability coefficient calculation formulae in the GB 50005-2017 standard and the regression method, the calculation method of the stability coefficient for CLT elements was proposed, and the values of the material parameters were determined. The result shows that the average deviation between fitting curve and calculated results of European and American standard is 5.43% and 3.73%, respectively, and the average deviation between the fitting curve and the actual test results was 8.15%. The stability coefficients calculation formulae could be used to predict the stability coefficients of CLT specimens with different slenderness ratios well.

[Determination of metal elements in paper sludges by ICP-AES].

Metal elements, especially the heavy metal element, need to be considered for resource utilization of paper sludge. Seventeen kinds of metal elements were determined by ICP-AES method, which were form two kinds of paper sludge from Anhui Shanying paper mill, one kind of paper sludge from Fujian Qingshan paper mill, and one kind of paper sludge from Fujian Zhongzhu paper mill. The results show that there are different amounts of metal elements in the 4 kinds of paper sludge including poisonous metal elements, such as Cr, etc, metal element which is poisonous when excessive, such as Fe, etc, and P and K which are beneficial for plant growth Al and Ca contents are maximal. The recovery ratio for Fujian Zhongzhu paper mill obtained by standard addition method is 94.4%-107.3%. Heavy metal elements content lower than the national standard GB/4284-84 "Control standards for pollutions in sludge form agricultural use". The order of heavy metal elements content is paper sludge from Fujian Zhongzhu paper mill

[Microfibril angle prediction of Eucalyptus pellita wood samples based on radial and tangential section by near infrared spectroscopy].

Near infrared spectroscopy (NIR) technique was applied to predict wood microfibril angle (MFA) of eucalyptus pellita in radial/tangential section. The MFA of small clear increment core samples were measured by X-ray diffractometry. After collecting the near infrared reflectance spectra of each sample, the NIR spectra were preprocessed with the second-derivative and the regression models were built for certain spectra. The calibration models were established using at least 159 samples with the partial least squares method and validated with full cross validation method. The results showed that high correlation coefficients were obtained between the laboratory-determined data and NIR fitted data. The finding suggests that an NIR instrument could be calibrated to estimate the limited MFA range of the increment core samples of eucalyptus pellita in radial/tangential section rapidly. Further work is required using different species wood sample sets that display a wide range of MFA variation.

[Analysis of effects of irradiation on the crystal size of daemonorops margaritae with X-ray diffractometry].

In order to find the relationships between the crystal size and the physical & mechanical properties, and to improve the levels of high value-added processing and utilizing for Chinese rattan resources, the daemonorops margaritae, Chinese unique rattan, was chosen as the research material, then the crystal size was measured and analyzed through the X-ray diffraction method before and after gamma-ray irradiation. The results show that the crystal width is in the range between 1.901 and 3.019 nm, and the average width is 2.403 nm. The crystal length is in the range between 4.118 and 28.824 nm with an average length of 10.907 nm. After irradiation, the width of daemonorops margaritae is in the range between 2.139 and 3.540 nm, and the average width is 2.569 nm, and the crystal length dramatically changes in the range between 5.765 and 38.432 nm with a mean of 15.530 nm. Both of the scope and the mean value of the crystal width and length increase after irradiation.

[Determination of lignin distribution during ageing of bamboo culms (Phyllostachys pubescens) with visible-light spectrophotometry].

The lignin distribution in different anatomical regions of developing moso bamboo Phyllostachys pubescens f. lutea Wen was investigated by means of optical microscope and visible-light microspectrophotometry coupled with the Wiesner and Maule reaction. The lignin is widely distributed in different tissues, in which there is a difference in lignin content between different ages, tissues and anatomical regions. Guaiacyl lignin and Syringyl lignin unit can be found in cell wall of fibre, parenchyma and vessel. Lignin content of secondary wall, cell corner and compound middle lamellae of fibre increased gradually within 12 months, then almost remained in the same level or decreased slowly in the culms with an age from 12 to 78 months. The lignification rate in secondary wall, cell corner and compound middle lamellae of fibre changed with age until they reached a relative steady value. There is no regular variation in lignin content with different radial location of culms and different location in fibre strands within one age. The secondary wall, compound middle lamellae of parenchyma and vessel secondary wall lignified rapidly within 12 months, and then changed slowly.

[Analysis of the microfibrilla angles & crystallinity index of Daemonorops Margaritae with X-ray diffractometry and the effects of gamma-ray irradiation].

In order to find out the properties and improve the levels of high value-added processing and utilization of Chinese rattan resources, the Daemonorops Margaritae, a Chinese unique rattan, was chosen as the research material, then the microfibril angles (MFA) & crystallinity index (CrI) were measured through the X-ray diffraction method, and the effects of gamma-ray irradiation upon the MFA & CrI were analyzed. The results show that the MFA of the cane varied from 33.4 degrees to 38.7 degrees with the average value of 36.1 degrees, and the MFA of the coretex were not larger than that of the core. The MFA were 36.2 and 35.8 degrees, 35.9 and 35.4 degrees, and 36.2 and 35.4 degrees before and after irradiation with a radiation dose rate of 2.5 x 10(3) Gy x h(-1) and radiation dose of 3, 9 and 15 kGy, and decreased 1.10%, 1.39% and 2.21% respectively compared with the former. The CrI was in the range of 24.8%-32.0%, and the average CrI was 28.6%. The CrI of coretex was larger than that of the core. Under the same radiation conditions, the CrI was 28.1% and 26.0%, 28.1% and 26.9%, and 28.5% and 27.1% before and after irradiation, and the latter decreased 7.58%, 4.34% and 4.70% respectively compared to the former. With the radiation dose of 3 kGy, the differences in CrI between with and without irradiation were most notable in the 0.001 level.