Effects of fiber compression and length distribution on the flexural properties of short kenaf fiber‐reinforced biodegradable composites

The effects of the fiber compression and the length distribution on the flexural properties of short kenaf fiber‐reinforced biodegradable composites were investigated. Two types of kenaf (KU and KT) that were different in the density and the length distribution were used as reinforcements. These fibers were mixed with a corn–starch‐based resin, and the composite specimens were fabricated by a hot press forming. The flexural modulus in the KU specimens was not different from that in the KT, despite the difference of the fiber Young's modulus (KU 14.5 GPa and KT 22.1 GPa). This was because the KU was compressed more than the KT in the composite specimen because of the lower density structure. However, in the longest fiber (10.5 mm), the flexural strength in the KT specimens was considerably higher by 67% than that in the KU. The reason was that the KT did not include the fibers below the critical length (4.2 mm) because of the narrower fiber distribution than the KU. In fact, the flexural strength in the KT specimen significantly decreased with decrease in the average fiber length, which included the fibers below the critical length. Moreover, the flexural modulus agreed well with the calculated values by Cox's model that incorporated the effect of the fiber compression. POLYM. COMPOS. 27:170–176, 2006. © 2006 Society of Plastics Engineers     

Synthesis and photoluminescence properties of fluorine-containing poly(phenylene vinylene) bearing hexafluorocyclopentene-fused phenanthrene unit

The intramolecular oxidative photocyclization of 1,2-diarylhexafluorocyclopentene ( 1 ) under light irradiation (λ = 365 nm) provided hexafluorocyclopentene-fused phenanthrene with formyl groups ( 2 ) in moderate yield. The copolymerization of 2 with tetraethyl(2,5-bis(dodecyloxy)-1,4-phenylene)bis(methylene)diphosphonate by the Horner–Wadsworth–Emmons reaction gave a fluorine-containing poly(phenylene vinylene), Polymer-2, in 41% yield. For comparison, a diphenylethene-type copolymer, Polymer-1, was also prepared analogously. The number-average molecular weights of Polymer-1 and Polymer-2 were 8900 and 3300 g mol^?1, respectively. The copolymers showed high thermal stability, as revealed by their thermogravimetric analysis. UV–visible spectra of the copolymers in CHCl₃ showed π–π* transition peaks at around 420 nm, and the peaks shifted to longer wavelengths by ca 10 nm for samples in film form. The photoluminescence spectra of Polymer-1 and Polymer-2 exhibited peaks at 542 and 560 nm in CHCl₃, respectively, whereas the photoluminescence intensity of Polymer-2 was very low in the solid state, presumably owing to the partial aggregation of the polymer molecules. © 2021 Society of Industrial Chemistry.     

Fiber optic-type compact dosimeter using Nd:YAG for basement investigation inside primary containment vessel

ABSTRACT

For decommissioning the Fukushima Dai-ichi Nuclear Power Station, information on the radiation environment such as dose rate and radionuclides inside the primary containment vessel (PCV) is crucial. The authors have developed a fiber optic-type compact dosimeter and demonstrated it for a basement investigation inside the PCV of Unit 1. The dosimeter consisted of a Nd:YAG crystal that emitted infrared photons of 1064 nm by gamma-ray irradiation, an optical fiber as signal transmitter, and a measurement instrument for pulse height analysis. The dose rate linearity of the dosimeter was evaluated in the dose rate range from 0.01 to 8760 Gy/h by using gamma rays emitted from Co-60. The Nd:YAG crystal installed in a sensor unit was placed in a shape changing robot, PMORPH2, and dose rate distributions were obtained at 10 measurement points. The dose rate increased gradually when the sensor unit was close to the surface of some sediment. A comparison of measured dose rate attenuations obtained at two measurement points and calculated results showed that Cs-137 might stay on the surface or inside the sediment as the dominate radionuclide.     

Deficiency of Lipin2 Results in Enhanced NF-κB Signaling and Osteoclast Formation in RAW-D Murine Macrophages

Lipin2 is a phosphatidate phosphatase that plays critical roles in fat homeostasis. Alterations in Lpin2, which encodes lipin2, cause the autoinflammatory bone disorder Majeed syndrome. Lipin2 limits lipopolysaccharide (LPS)-induced inflammatory responses in macrophages. However, little is known about the precise molecular mechanisms underlying its anti-inflammatory function. In this study, we attempted to elucidate the molecular link between the loss of lipin2 function and autoinflammatory bone disorder. Using a Lpin2 knockout murine macrophage cell line, we showed that lipin2 deficiency enhances innate immune responses to LPS stimulation through excessive activation of the NF-κB signaling pathway, partly because of TAK1 signaling upregulation. Lipin2 depletion also enhanced RANKL-mediated osteoclastogenesis and osteoclastic resorption activity accompanied by NFATc1 dephosphorylation and increased nuclear accumulation. These results suggest that lipin2 suppresses the development of autoinflammatory bone disorder by fine-tuning proinflammatory responses and osteoclastogenesis in macrophages. Therefore, this study provides insights into the molecular pathogenesis of monogenic autoinflammatory bone disorders and presents a potential therapeutic intervention.     

Cold-Sprayed TiO2 Coatings from Nanostructured Ceramic Agglomerated Powders

In this work, synthesis of agglomerated TiO₂, which is ready to be used after synthesis via a simple hydrolysis process, is described. The as-synthesized TiO₂ powders were characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Field Emission Scanning Electron Microscope (FE-SEM), Transmission Electron Microscope (TEM) and DTA. DTA curve indicated that addition of (NH₄)₂SO₄ into the starting precursor has accelerated the hydrolysis of titanyl sulfate. The XRD patterns showed that single-phase anatase TiO₂ was produced using low-temperature hydrolysis at 80°C. SEM confirmed that the as-synthesized powders were in agglomerated form and in micro size. Addition of a structure-directing agent (SDA), (NH₄)₂SO₄, promotes agglomeration, with a denser closed packing of particle arrangement, which reduces the number of existing porosities in the synthesized powder. The TEM image showed that the primary particles were nanoparticles. The preliminary study of coating formation depicted that the powder obtained could be used as the feedstock powder for the cold spray (CS) process to make the coating as it can be deposited onto the ceramic tile substrate.     

Dental Pulp-Derived Mesenchymal Stem Cells for Modeling Genetic Disorders

A subpopulation of mesenchymal stem cells, developmentally derived from multipotent neural crest cells that form multiple facial tissues, resides within the dental pulp of human teeth. These stem cells show high proliferative capacity in vitro and are multipotent, including adipogenic, myogenic, osteogenic, chondrogenic, and neurogenic potential. Teeth containing viable cells are harvested via minimally invasive procedures, based on various clinical diagnoses, but then usually discarded as medical waste, indicating the relatively low ethical considerations to reuse these cells for medical applications. Previous studies have demonstrated that stem cells derived from healthy subjects are an excellent source for cell-based medicine, tissue regeneration, and bioengineering. Furthermore, stem cells donated by patients affected by genetic disorders can serve as in vitro models of disease-specific genetic variants, indicating additional applications of these stem cells with high plasticity. This review discusses the benefits, limitations, and perspectives of patient-derived dental pulp stem cells as alternatives that may complement other excellent, yet incomplete stem cell models, such as induced pluripotent stem cells, together with our recent data.     

Membrane processing of fruit juices and beverages: a review

Membrane technology for the processing of fruit juices and beverages has been applied mainly for clarification using ultrafiltration and microfiltration, and for concentration using reverse osmosis. The effects of product preparation, membrane selection, and operating parameters are important factors influencing filtration rate and product quality. Technological advances related to the development of new membranes, improvement in process engineering, and better understanding of fruit beverage constituents have expanded the range of membrane separation processes. Developments in novel membrane processes, including electrodialysis and pervaporation, increased the array of applications in combination with other technologies for alternate uses in fruit juices and beverages.     

Characterization of Water Extractable Crude Polysaccharides from Cherry,Raspberry, and Ginseng Berry Fruits: Chemical Composition and Bioactivity

Water extractable crude polysaccharides from three sweet cherry varieties, raspberries, and ginseng berry pulp were evaluated for their chemical composition, structural features, molecular weight, and bioactive properties. The yields of the crude polysaccharides isolated from cherries, raspberries, and ginseng berry pulp ranged from 0.79 to 0.18% on a dry weight fruit basis. All of the crude polysaccharides contained protein, phenolic compounds, and uronic acid. Each crude polysaccharide contained the sugar monomers: rhamnose, arabinose, xylose, mannose, galactose, and glucose. Of the water extractable polysaccharides obtained from the mature fruits, the crude polysaccharides from the raspberries had the highest molecular weight while the crude polysaccharides from the ginseng berry pulp had the smallest molecular weight. Results from Fourier transform infrared spectroscopy suggested that the crude polysaccharides contained a monosaccharide with six carbon atoms in a D-glucopyranose ring and a protein component. The crude polysaccharides from cherries, raspberries, and ginseng berry pulp were shown to possess antioxidant activity as determined with the ferric reducing antioxidant power and the 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. The effect of crude polysaccharides on: (1) caspase 3 activation, which was determined using a hypoxia/reoxygenation model, and (2) immunostimulation, which was determined by evaluating the inflammatory mediator response, were examined. Only crude polysaccharides obtained from certain varieties of sweet cherries inhibited caspase 3 activation in a dose-dependent manner, while only the crude polysaccharides obtained from ginseng berry pulp stimulated immune function. Crude polysaccharides present in small fruits do possess bioactivities that may enhance human health.