Effects of Temperature on the Compressive Strength Parallel to the Grain of Bamboo Scrimbe.

The objective of this study was to investigate the compressive strength parallel to the grain of bamboo scrimber during and after exposure to various temperatures, in a range from 20 to 225 °C. These data were used to provide a basis for the evaluation of the fire performance of bamboo structures. A total of 152 specimens, assembled as group "during-fire" and "post-fire", were tested during and after exposure to high temperatures. The experimental results indicated that there were significant differences in compressive properties between the "during-fire" and "post-fire" groups. At one temperature level, the compressive strength and modulus of elasticity of the "post-fire" group were significantly higher than those properties of the "during fire" group, but the ductility coefficient was reversed. FTIR analysis results showed that 175 °C was a key turning point, at which thermal decomposition occurred in the cellulose of the bamboo and phenolic resin.

Experimental and Statistical Evaluation of the Size Effect on the Bending Strength of Dimension Lumber of Northeast China Larch.

This study investigated the size effect on the bending strength (modulus of rupture-MOR) of dimension lumber of Northeast China larch (Larix gmelinii); providing a basis for the further application in light wood frame construction. Experimental and statistical evaluations were conducted on the bending strength. A total of 2409 full-size dimension lumber samples were tested by static bending tests; which included three different sizes: 2 × 3; 2 × 4; and 2 × 6. Results indicate that the size has a significant effect on the MOR. Both the chi-square (χ²) and Kolmogorov-Smirnov (K-S) test results show that the lognormal distribution generally fits to the MOR better than to the normal distribution. Additionally; the effects of partial safety factor (γR) and live-to-dead load ratio (ρ) were studied by reliability analysis. Reliability analysis results indicate that the reliability index increases nonlinearly with the decrease of γR and the rise of ρ. Finally; the design value of bending strength and its adjusting factor of size effect of 2 × 3; 2 × 4; and 2 × 6 larch dimension lumber were obtained according to the Chinese National Standards' requirements of the reliability index.

[Pothole ecosystem in mountain river: A review].

The pothole is one of the special habitats in river ecosystems, which is simply structured, well-defined, food chain-short, and easily controlled, thus making it a model system in ecological, evolutionary and phenological studies. Here we first reviewed hydrological, chemical and physical characteristics of potholes, their biological community (biodiversity, environmental factors) as well as food chain (competition, predation and parasitism) in mountain rivers. The differences between pothole ecosystems and river ecosystems in hydrological characteristics, biological community and food-chain were analyzed. Hydrological, physical chemical, and ecological characteristics of potholes were largely unexplored in China. Finally, we suggested future directions and recommendations in pothole ecosystems.

[Distribution and species composition of hyporheic macroinvertebrates in a mountain stream].

Hyporheic macroinvertebrates are an important component of stream ecosystem. The composition and distribution of the hyporheic macroinvertebrates were investigated using artificial substrates in the upper reaches of Heishuitan River in August, December 2013 and April 2014. The results indicated that a total of 27 microinvertbrate species were identified in all three seasons. In summer, 22 species were identified, accounting for 81.8% of aquatic insects. 16 species were identified both in winter and spring, accounting for 75.0% and 62.5% of aquatic insects, respectively. The density of macroinvertebrate assemblage was significantly lower in summer than in winter and spring, and was the highest in spring. The biomass of macroinvertebrate assemblage was significantly higher in winter than in summer and spring, and was the lowest in summer. Species richness, Shannon index and Pielou index all had no significant difference among the three seasons. The density and richness of macroinvertebrates decreased with bed depth, and the maximum invertebrate density was found within the top 20 cm of the stream bed. Collector-filterer and collector-gatherer were the dominant functional feeding group in all three seasons. The community structure and temporal-spatial distribution of macroinvertebrates were determined by interactions and life history strategy of macroinvertebrates, and physical-chemical factors of hyporheic zone.

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.

[Research advances in macroinvertebrate ecology of the stream hyporheic zone].

The stream hyporheic zone is an ecotone of surface water-ground water interactions, which is rich in biodiversity, and is an important component of stream ecosystem. The macroinvertebrates, which are at the top of food webs in the hyporheic zone to directly influence the matter and energy dynamics of the hyporheic zone, and are potential indicators of river ecological health to adjust the function of environment purification and ecological buffer. The macroinvertebrates in the hyporheic zone are divided into three categories: stygoxenes, stygophiles and stygobites. The key factors which influenced macroinvertebrates distribution in the hyporheic zone are physical size of interstitial spaces, interstitial current velocity, dissolved oxygen (DO), water temperature, available organic matter, hydraulic conductivity and hydraulic retention time. A suitable sampling method should be used for diverse research purposes in the special ecological interface. In the future, some necessary researches should focus on the life-history and life history strategy of the macroinvertebrates in the hyporheic zone, the quantitative analysis on the matter and energy dynamics in the ecological system of stream, the assessment systems of river ecological health based on the macroinvertebrates of the stream hyporheic zone, and the ecological significance of the hyporheic zone as a refuge for distribution and evolution of the macroinvertebrates.

[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.

[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.

[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.

[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.

[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.

[Nano TiO2 modification of bamboo and its antibacterial and mildew resistance performance].

Bamboo, a kind of forest resources only less important than wood, is especially easy to mildew during outdoor service. In this work, TiO2 sols were synthesized under low-temperature condition by sol-gel method. The crystalline TiO2 film with a diameter of approximate 40-90 nm was used to coat bamboo at low temperature. The TiO2 films were characterized by nuclear magnetic resonance spectrometer (NMR), field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDAX). The effects of temperature on film crystal forms, its antibacterial, and mildew resistance properties were mainly investigated. The results showed that the modified bamboo in low temperature solution (20, 60 and 105 degrees C) was mainly covered with anatase nano TiO2 film. The nano-TiO2-modified bamboo maintained the natural wood color, texture and structure, and improved its anti-bacterial property from non-anti-bacterial to anti-Escherichia coli, and the bactericidal rate reached over 99%. Meanwhile its mildew resistance property increased over 10 times. So this method is expected to become the new way of functional improvement on bamboo, and has the reference meaning for the protection and improvement of wood and other biologic materials.

[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

[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.

[FTIR and XPS spectroscopic studies of photodegradation of Moso Bamboo (Phyllostachys pubescens Mazel)].

The photodegradation process of bamboo involves very complex chemical reactions. In the present study, surface deterioration of Moso bamboo (Phyllostachys pubescens Mazel) was carried out by a xenon fade meter which can simulate sunlight irradiation, and Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopic (XPS) techniques were used to characterize the resulting changes in the chemical structure and composition of bamboo surface. XPS results showed that light irradiation resulted in significant increases in oxygen (O) content and O/C ratio. Besides, changes were also identified from the detailed C(ls) spectra, with a remarkable decrease in C1 component (C-C) and simultaneous increases in the components of C2 (C-O), C3 (C = O) and C4 (O-C = O), suggesting that the carbon atoms at bamboo surface were highly oxidized. FTIR results showed that lignin was susceptible to light irradiation and was significant degraded after treatment, as indicated by remarkable decreases in the intensity of lignin associated bands (e. g. 1 604, 1 512 and 1 462 cm(-1)). This was accompanied by the formation of new carbonyl compounds as shown by an obvious increase in the intensity of non-conjugated carbonyl group at 1 735 cm(-1), which further indicated the photo-oxidation of bamboo surface. The polysaccharides (cellulose and hemicellulose) components, however, were less influenced by light irradiation, and their relative content at bamboo surface increased significantly due to lignin degradation.

[FTIR spectroscopic studies of the photo-discoloration of Chinese fir].

Wood or wood products undergo rapid degradation of surface characteristics and quality indicated by changes in wood color during outdoor exposure owing to a combination of various weathering factors, which may result in significant reduction in utilization values of wood. In the present study, photodegradation of wood surfaces of Chinese fir (Cunninghamia lanceolata) was carried out by a Xenon test chamber which can simulate sunlight irradiation. A Fourier transform infrared (FTIR) spectroscopy technique was used to study chemical changes caused by irradiation during photo-discoloration of wood surfaces, and the relationship between the changes in color and chemical composition was established. Results indicated that, during the process of irradiation, the intensity of absorption bands at 1512, 1462, 1269 and 1227 cm(-1) decreased significantly, accompanied by a successive increase in the intensity of band at 1720-1735 cm(-1). Lignin was the most sensitive component to the degradation process and underwent severe photodegradation during the process of irradiation. This was accompanied by formation of new carbonyl compounds, which indicated the photo-oxidation of wood surfaces. In the initial 80 h of irradiation, the degradation of lignin and formation of carbonyl groups were intense, and then became insignificant in longer exposure duration. Degradation of polysaccharides (cellulose and hemicellulose)also occurred during the process. Overall, color changes (deltaE*) were correlated well with the degradation of lignin and relative increase in the content of carbonyl groups during the process of irradiation.

[Discrimination of wood biological decay by NIR and partial least squares discriminant analysis (PLS-DA)].

Extensive research has demonstrated that near infrared spectroscopy (NIR) and partial least squares discriminant analysis (PLS-DA) can be used to rapidly discriminate or detect a wide variety of food, medicine and agricultural products. The use of NIR coupled with PLS-DA to detect wood biological decay was investigated in the present paper. The results showed that the correlation between the predicted category variable of calibration and validation and the measured category variable is significant with a correlation coefficient (r) over 0.94 and low SEC and SEP (< 0.17); the discriminant accuracy for the non-decay, white-rot and brown-rot decay samples are 100% (deviation < 0.5) by the PLS-DA model based on the test set of samples; the discriminant accuracy by PLS-DA model is better than that by SIMCA model. It's suggested that NIR spectroscopy coupled with PLS-DA could be used to rapidly detect wood biological decay.

[The analysis of wood microfibril angle by near infrared spectroscopy and X-ray diffractometry].

In the present paper, near infrared (NIR) spectroscopy and X-ray diffractometry were used to rapidly predict the microfibril angle (MFA). MFA is one of the most important factors affecting wood properties. Wood resource utilization and tree improvement programs require cost-effective methods for the rapid analysis of thousands of samples. In the experiment, the average MFA of each sample were rapidly measured by X-ray scanning diffractometry. Then, the PLS model was built between NIR data and MFA by the X-ray measured. As a result, a very strong linear relationship has been found between NIR spectra fitted and X-ray measured, and the coefficients (r2) of calibration and prediction models were 0.867 and 0.816 respectively.