Investigation of bamboo pulp fiber-reinforced unsaturated polyester composites

Mechanical pulp fibers (MPFs) and chemical pulp fibers (CPFs) from moso bamboo have been characterized in terms of their length and width distributions, and their reinforcing effects in unsaturated polyester (UPE) composites have also been investigated. CPF-UPE composites had much higher tensile strength, flexural strength, and flexural modulus than MPF-UPE composites. CPF-UPE composites also absorbed less water than MPF-UPE composites. Treatments of the fibers with a combination of 1,6-diisocyanatohexane (DIH) and 2-hydroxyethyl acrylate (HEA) significantly increased the tensile strength, flexural strength, flexural modulus, and water resistance of the resulting composites. Fourier transform infrared and X-ray photoelectron spectroscopy analyses indicated that DIH-HEA was bound onto bamboo fibers (BFs) via carbamate linkages. The scanning electron microscopy images of the tensile-fractured surfaces of the composites revealed that the DIH-HEA treatments for BFs greatly improved the interfacial adhesion between the fibers and UPE resins.Keywords: water resistance, unsaturated polyester, mechanical properties, surface treatments, bamboo fibers, interfacial adhesionKeywords: water resistance, unsaturated polyester, mechanical properties, surface treatments, bamboo fibers, interfacial adhesio

Effect of the Combined Extracts of Herba Epimedii and Fructus Ligustri Lucidi on Sex Hormone Functional Levels in Osteoporosis Rats

The combination of Herba Epimedii and Fructus Ligustri Lucidi has been used to treat osteoporosis for almost 50 years by Professor Shizeng Li, a famous doctor of traditional Chinese medicine (TCM). However, it is unclear whether the combination of the effective constituents of the two herbs may have a protective influence on the skeleton. In the present study, we investigated the effects of the combination extracts of Herba Epimedii and Fructus Ligustri Lucidi on rat model of osteoporosis induced by retinoic acid by gavage. With administrations of the combination extracts of the two herbs (50, 100, and 200 mg/kg/day) via oral gavage for 3 weeks, bone mineral density (BMD), femur histomorphometry, some sex hormones, and sex hormone receptors were measured. Results showed that the combined extracts could increase BMD, affect bone histomorphometry, coordinate the sex hormones at the level of hypothalamus-pituitary-gonad axis, and increase the protein and mRNA expressions of sex hormone receptors. The findings suggested that the combination extracts of Herba Epimedii and Fructus Ligustri Lucidi might be beneficial as an alternative medicine for the prevention and treatment of osteoporosis

Magnetic properties of Ce-containing Pr/Nd-Fe-B sintered magnets by diffusing Nd-Dy-Al alloy

In this study, 5% wt Ce-containing sintered Pr/Nd-Ce-Fe-B magnets were processed by grain boundary diffusion (GBD) with NdxDy90-xAl10 alloy (x = 0, 10, and 20 correspond to N0, N10, and N20, respectively). After the GBD process, the coercivity of magnets increased from 1,124.7 to 1,656.4, 1,673.9, and 1,584.8 kA/m, for N0, N10, and N20, respectively. Microstructure analysis revealed continuous RE-rich intergranular phases around matrix grains, which by weakening the magnetic coupling effect between ferromagnetic matrix grains, thus, leads to coercivity improvement. N10 had the same coercivity enhancement as N0, while the Dy utilization for N10 is lower than that for N0. The SEM results showed that the inclusion of Nd leads to the formation of a network of low-melting grain boundary phases, providing channels for subsequent Dy diffusion. A CeFe2 phase was found in the 5% wt Ce-containing magnet, which hindered diffusion due to its high melting point; in order to inhibit the negative impact of CeFe2 and reveal the diffusion mechanism in the Ce-containing magnet, DyH3, as a diffusion source, was applied to 5% wt-Ce-containing magnets simultaneously; after the GBD process, Nd10Dy90Al10 alloy, as a diffusion source, has better coercivity enhancement than DyH3, due to the deeper diffusion of the Dy element in the Nd10Dy90Al10 diffusion

Active Ingredients of Epimedii Folium and Ligustri Lucidi Fructus Balanced GR/HSP90 to Improve the Sensitivity of Asthmatic Rats to Budesonide

This study aimed to investigate the possible molecular mechanisms of active ingredients of Epimedii Folium (EF) and Ligustri Lucidi Fructus (LLF) combined with Budesonide (Bun) in asthmatic rats. Rats were divided into 5 groups, including normal group, asthma model group, Bun group, group of active ingredients of EL and LLF (EL), and group of coadministration of Bun with EL (Bun&EL). The asthmatic model was prepared by ovalbumin sensitizing and challenging. Lymphocyte apoptosis, GR protein and binding, and the protein and mRNA of GRα, GRβ, and HSP90 were tested. The results showed that Bun&EL ① markedly increased lymphocyte apoptosis, GR and HSP90 protein, and GR binding in BALF and ② enhanced the expressions of GRα and HSP90 and the ratio of GRα to GRβ or to HSP90 both in protein and in mRNA levels in lung, ③ while decrease occurred in GRβ mRNA and the mRNA ratio of GRβ to HSP90 compared with asthma or Bun group. Moreover, there was a significant correlation between GRα and GRβ in protein level, or between GRα and HSP90 both in protein and in mRNA levels. EL may effectively enhance the sensitivity of asthmatic rats to Bun via balancing GR/HSP90. And these findings will be beneficial for the treatment of asthma in the future

Mechanical and Thermal Properties of Hemp Fiber-Unsaturated Polyester Composites Toughened by Butyl Methacrylate

Hemp fiber-reinforced unsaturated polyester (UPE) composites were prepared by hand lay-up compression molding. The UPE resins were modified with butyl methacrylate (BMA) to improve the flexibility and toughness of the hemp-UPE composites. The results indicate that the toughness of the composites significantly increased as BMA usage increased. Compared to the unmodified UPE composites, the composites obtained from BMA-modified UPE resins had 27.4, 63.0, and 36.6% greater elongation at break, flexural strain, and impact strength, respectively. The optimum BMA usage to achieve an adequate balance of stiffness and toughness is 20 to 30%. Dynamic mechanical analysis (DMA) indicated that incorporation of BMA significantly decreased the storage modulus and glass transition temperature of the composites and increased its damping parameter due to the introduction of flexible segments into the UPE resins. Thermogravimetric analysis showed that the thermal stability of the composites decreased slightly following the incorporation of BMA. Scanning electron microscopy images of the impact-fractured surfaces of the composites revealed that BMA incorporation improved interfacial adhesion between hemp fibers and UPE matrices and that the main mechanism for the increase in the toughness of the composites was the added ductility of the matrices

Variability of Aboveground Litter Inputs Alters Soil Carbon and Nitrogen in a Coniferous–Broadleaf Mixed Forest of Central China

Global changes and human disturbances can strongly affect the quantity of aboveground litter entering soils, which could result in substantial cascading effects on soil biogeochemical processes in forests. Despite extensive reports, it is unclear how the variations in litter depth affect soil carbon and nitrogen cycling. The responses of soil carbon and nitrogen to the variability of litter inputs were examined in a coniferous⁻broadleaf mixed forest of Central China. The litter input manipulation included five treatments: no litter input, natural litter, double litter, triple litter, and quadruple litter. Multifold litter additions decreased soil temperature but did not affect soil moisture after 2.5 years. Reductions in soil pH under litter additions were larger than increases under no litter input. Litter quantity did not affect soil total organic carbon, whereas litter addition stimulated soil dissolved organic carbon more strongly than no litter input suppressed it. The triggering priming effect of litter manipulation on soil respiration requires a substantial litter quantity, and the impacts of a slight litter change on soil respiration are negligible. Litter quantity did not impact soil total nitrogen, and only strong litter fluctuations changed the content of soil available nitrogen (nitrate nitrogen and ammonium nitrogen). Litter addition enhanced soil microbial biomass carbon and nitrogen more strongly than no litter input. Our results imply that the impacts of multifold litter inputs on soil carbon and nitrogen are different with a single litter treatment. These findings suggest that variability in aboveground litter inputs resulting from environmental change and human disturbances have great potential to change soil carbon and nitrogen in forest ecosystems. The variability of aboveground litter inputs needs to be taken into account to predict the responses of terrestrial soil carbon and nitrogen cycling to environmental changes and forest management

A Review on Styrene Substitutes in Thermosets and Their Composites

In recent decades, tremendous interest and technological development have been poured into thermosets and their composites. The thermosets and composites with unsaturated double bonds curing system are especially concerned due to their versatility. To further exploit such resins, reactive diluents (RDs) with unsaturated sites are usually incorporated to improve their processability and mechanical properties. Traditional RD, styrene, is a toxic volatile organic compound and one of the anticipated carcinogens warned by the National Institute of Health, USA. Most efforts have been conducted on reducing the usage of styrene in the production of thermosets and their composites, while very few works have systematically summarized these literatures. Herein, recent developments regarding styrene substitutes in thermosets and their composites are reviewed. Potential styrene alternatives, such as vinyl derivatives of benzene and (methyl)acrylates are discussed in details. Emphasis is focused on the strategies on developing novel RD monomers through grafting unsaturated functional groups on renewable feedstocks such as carbohydrates, lignin, and fatty acids. This review also highlights the development and characteristics of RD monomers and their influence on processability and mechanical performance of the resulting thermosets and composites

Targeted deep sequencing reveals high diversity and variable dominance of bloom-forming cyanobacteria in eutrophic lakes

Cyanobacterial blooms in eutrophic lakes are severe environmental problems worldwide. To characterize the spatiotemporal heterogeneity of cyanobacterial blooms, a high-throughput method is necessary for the specific detection of cyanobacteria. In this study, the cyanobacterial composition of three eutrophic waters in China (Taihu Lake, Dongqian Lake, and Dongzhen Reservoir) was determined by pyrosequencing the cpcBA intergenic spacer (cpcBA-IGS) of cyanobacteria. A total of 2585 OTUs were obtained from the normalized cpcBA-IGS sequence dataset at a distance of 0.05. The 238 most abundant OTUs contained 92% of the total sequences and were classified into six cyanobacterial groups. The water samples of Taihu Lake were dominated by Microcystis, mixed Nostocales species, Synechococcus, and unclassified cyanobacteria. Besides, all the samples from Taihu Lake were clustered together in the dendrograrn based on shared abundant OTUs. The cyanobacterial diversity in Dongqian Lake was dramatically decreased after sediment dredging and Synechococcus became exclusively dominant in this lake. The genus Synechococcus was also dominant in the surface water of Dongzhen Reservoir, while phylogenetically diverse cyanobacteria coexisted at a depth of 10 m in this reservoir. In summary, targeted deep sequencing based on cpcBA-IGS revealed a large diversity of bloom-forming cyanobacteria in eutrophic lakes and spatiotemporal changes in the composition of cyanobacterial communities. The genus Microcystis was the most abundant bloom-forming cyanobacteria in eutrophic lakes, while Synechococcus could be exclusively dominant under appropriate environmental conditions. (C) 2017 Elsevier B.V. All rights reserved