16 research outputs found
Optimizing the Preparation Process of Bamboo Scrimber with Bamboo Waste Bio-Oil Phenolic Resin Using Response Surface Methodology
No full textBamboo scrimber is a new type of biomass fiber-based composite material with broad application. In this study, self-developed bio-oil phenolic resin (BPF) was used to prepare bamboo scrimber. The effects of hot-pressing temperature, hot-pressing time, and BPF resin solid content on the modulus of rupture (MOR) and modulus of elasticity (MOE) were systematically investigated through single-factor experiments and response surface methodology (RSM). According to the Box-Behnken design (BBD) experiment of the RSM, the effects of all three factors on MOR and MOE are significant. The effects of the main factors affecting the MOR and MOE decreased in the order of resin solid content, hot-pressing temperature, and hot-pressing time. Based on BBD, the optimal conditions for the preparation of bamboo scrimber were determined as follows: a hot-pressing temperature of 150 °C, a hot-pressing time of 27.5 min, and a resin solid content of 29%. Under these conditions, the MOR is 150.05 MPa and the MOE is 12,802 MPa, which are close to the theoretical values, indicating that the optimization results are credible. This study helps to promote the full utilization of bamboo components and provides a reference for the development of high-quality bamboo scrimber
Hydrothermal Aging Properties of Three Typical Bamboo Engineering Composites
No full textStudy investigates the hygroscopic characteristics of three typical bamboo engineering composites (Bamboo scrimber (BS), bamboo bundle/wood laminated veneer lumber (BLVL), and bamboo laminated timber (BLT)) as well as predict their performance changes and service life in hot humid environments
Vibration Performance of Bamboo Bundle/Wood Veneer Composite Floor Slabs for Joist-Type Floor Coverings
No full textBamboo engineering materials are green, high-strength, tough, durable, and structurally safe, and have promising application prospects in various modern green and low-carbon buildings. To investigate the vibration behavior of bamboo-bundle laminated veneer lumber (BLVL) for use in floor slabs, this study designed two kinds of full-scale vibration tests under a pedestrian load: an extraction hammer impact test and a static concentrated load test. The results are expected to provide a theoretical foundation and data to support the application of bamboo bundle veneer laminated composite materials in the construction field. The results showed that the self-oscillation frequency and mid-span deflection of the BLVL composite met the requirements of multiple relevant regulations when used as the structural material of floor slabs. The BLVL floor slab had greater flexural stiffness and better vibration-damping performance than the OSB floor slab. The first-order self-oscillation frequency of the BLVL composite floor slab was 13.769 Hz, the damping ratio of the first three orders of modalities was 1.262–2.728%, and the maximum static deflection in the span of the joist was 0.932 mm under a 1 kN concentrated load. The 1 kN static deflection of the BLVL was reduced by 22.33%, and the root mean square (RMS) acceleration of the walking load response was significantly lower than that of the OSB floor slab. The preparation of BLVL composite materials through homogeneous lamination of bamboo bundle veneer and wood veneer may help to improve the vibration behavior of bamboo–wood structures such as floor slabs and walls
Monitoring Method of Injection-type Generator Stator-to-earth Insulation State in Neutral Point Combined Grounding Mode
No full textBamboo-Inspired Renewable, High-Strength, Vibration-Damping Composites for Structural Applications
No full textRenewable
structural materials derived from natural biological
materials can potentially replace non-renewable synthetic materials
for civil engineering and transportation applications. Here, inspired
by the functional gradient structure of bamboo, we propose a simple
and efficient two-step preparation strategy to convert natural bamboo
into a lightweight, high-strength, damping, and sound-insulating structural
engineering material called densified bundle-laminated veneer lumber
(DBLVL). DBLVL was prepared by finely grading and thinning three layers
of bamboo slices and removing the lignin and hemicelluloses from the
surface of bamboo bundles. This was followed by penetrating the phenol
formaldehyde resin and then solidifying and densifying it in situ.
DBLVL had superior mechanical properties due to its bamboo-like gradient
laminated structure, three-dimensional network distribution of adhesive
under high temperature and high pressure, in situ curing, and solid
interfacial bonding. It had a specific tensile strength of 297 MPa
cm3 g–1, which was superior to those
of many other construction materials. The tensile strength of DBLVL
reached 363 MPa, and the bending strength reached 219 MPa, which were
97.28 and 92.11% higher than those of natural bamboo, respectively.
The impact toughness reached 15.4 J/cm2. DBLVL also showed
excellent damping and vibration reduction (the first three damping
ratios were 2.35, 1.81, and 2.40%) and dimensional stability (the
thickness expansion rate after 24 h of water absorption was 4.43%).
Because of its excellent mechanical properties and hygrothermal stability,
DBLVL is expected to replace non-renewable synthetic materials as
a green and sustainable structural material for engineering applications
An experimental rabbit model of symptomatic cerebral vasospasm with in�vivo neuroimaging assessment and ex�vivo histological validation
No full textA High-Resolution Linkage Map Construction and QTL Analysis for Morphological Traits in Anthurium (<i>Anthurium andraeanum</i> Linden)
No full textAnthurium andraeanum Linden is a prominent ornamental plant belonging to the family Araceae and is cultivated worldwide. The morphology characteristics are crucial because they significantly impact ornamental values, commercial properties, and the efficiency of space utilization in production. However, only a few related investigations have been conducted in anthurium to date. In this study, an F1 genetic segregation population containing 160 progenies was generated through hybridization between potted and cut anthurium varieties. Fifteen morphological traits were assessed and revealed substantial levels of genetic variation and widespread positive correlation. Based on specific length amplified fragment (SLAF) sequencing technology, 8171 single nucleotide polymorphism (SNP) markers were developed, and the high-density linkage map of 2202.27 cM in length distributed on 15 linkage groups was constructed successfully, with an average distance of 0.30 cM. Using the inclusive composite interval mapping (ICIM) method, 59 QTLs related to 15 key morphological traits were successfully identified, which explained phenotypic variance (PVE) ranging from 6.21% to 17.74%. Thirty-three of those associated with 13 traits were designated as major QTLs with PVE > 10%. These findings offer valuable insights into the genetic basis of quantitative traits and are beneficial for molecular marker-assisted selection (MAS) in anthurium breeding
Vitamin D Signaling through Induction of Paneth Cell Defensins Maintains Gut Microbiota and Improves Metabolic Disorders and Hepatic Steatosis in Animal Models
No full textMetabolic syndrome (MetS), characterized as obesity, insulin resistance, and non-alcoholic fatty liver diseases (NAFLD)，is associated with vitamin D insufficiency/deficiency in epidemiological studies, while the underlying mechanism is poorly addressed. On the other hand, disorder of gut microbiota, namely dysbiosis, is known to cause MetS and NAFLD. It is also known that systemic inflammation blocks insulin signaling pathways, leading to insulin resistance and glucose intolerance, which are the driving force for hepatic steatosis. Vitamin D receptor (VDR) is highly expressed in the ileum of the small intestine，which prompted us to test a hypothesis that vitamin D signaling may determine the enterotype of gut microbiota through regulating the intestinal interface. Here, we demonstrate that high-fat-diet feeding (HFD) is necessary but not sufficient, while additional vitamin D deficiency (VDD) as a second hit is needed, to induce robust insulin resistance and fatty liver. Under the two hits (HFD+VDD), the Paneth cell-specific alpha-defensins including α-defensin 5 (DEFA5), MMP7 which activates the pro-defensins, as well as tight junction genes, and MUC2 are all suppressed in the ileum, resulting in mucosal collapse, increased gut permeability, dysbiosis, endotoxemia, systemic inflammation which underlie insulin resistance and hepatic steatosis. Moreover, under the vitamin D deficient high fat feeding (HFD+VDD), Helicobacter hepaticus, a known murine hepatic-pathogen, is substantially amplified in the ileum, while Akkermansia muciniphila, a beneficial symbiotic, is diminished. Likewise, the VD receptor (VDR) knockout mice exhibit similar phenotypes, showing down regulation of alpha-defensins and MMP7 in the ileum, increased Helicobacter hepaticus and suppressed Akkermansia muciniphila. Remarkably, oral administration of DEFA5 restored eubiosys, showing suppression of Helicobacter hepaticus and increase of Akkermansia muciniphila in association with resolving metabolic disorders and fatty liver in the HFD+VDD mice. An in vitro analysis showed that DEFA5 peptide could directly suppress Helicobacter hepaticus. Thus, the results of this study reveal critical roles of a vitamin D/VDR axis in optimal expression of defensins and tight junction genes in support of intestinal integrity and eubiosis to suppress NAFLD and metabolic disorders
Vitamin D Signaling through Induction of Paneth Cell Defensins Maintains Gut Microbiota and Improves Metabolic Disorders and Hepatic Steatosis in Animal Models
No full textProspective observational cohort study on grading the severity of postoperative complications in global surgery research
No full textNestle Health Sciences
