Cross-community knowledge building with idea thread mapper

Research on computer-supported collaborative learning faces the challenge of extending student collaboration to higher social levels and enabling cross-boundary interaction. This study investigated collaborative knowledge building among four Grade 5 classroom communities that studied human body systems with the support of Idea Thread Mapper (ITM). While students in each classroom collaborated in their local (home) discourse space to investigate various human body functions, they generated reflective syntheses— “super notes”—to share knowledge progress and challenges in a cross-community meta-space. As a cross-community collaboration, students from the four classrooms further used the Super Talk feature of ITM to investigate a common problem: how do people grow? Data sources included classroom observations and videos, online discourse within each community, students’ super notes and records of Super Talk discussion shared across the classrooms, and student interviews. The results showed that the fifth-graders were able to generate high quality super notes to reflect on their inquiry progress for cross-classroom sharing. Detailed analysis of the cross-classroom Super Talk documented students’ multifaceted understanding constructed to understand how people grow, which built on the diverse ideas from each classroom and further contributed to enriching student discourse within each individual classroom. The findings are discussed focusing on how to approach cross-community collaboration as an expansive and dynamic context for high-level inquiry and continual knowledge building with technology support.

     

Supercritical Carbon Dioxide Treatment of Porous Silicon Increases Biocompatibility with Cardiomyocytes

Porous silicon is of current interest for cardiac tissue engineering applications. While porous silicon is considered to be a biocompatible material, it is important to assess whether post-etching surface treatments can further improve biocompatibility and perhaps modify cellular behavior in desirable ways. In this work, porous silicon was formed by electrochemically etching with hydrofluoric acid, and was then treated with oxygen plasma or supercritical carbon dioxide (scCO₂). These processes yielded porous silicon with a thickness of around 4 μm. The different post-etch treatments gave surfaces that differed greatly in hydrophilicity: oxygen plasma-treated porous silicon had a highly hydrophilic surface, while scCO₂ gave a more hydrophobic surface. The viabilities of H9c2 cardiomyocytes grown on etched surfaces with and without these two post-etch treatments was examined; viability was found to be highest on porous silicon treated with scCO₂. Most significantly, the expression of some key genes in the angiogenesis pathway was strongly elevated in cells grown on the scCO₂-treated porous silicon, compared to cells grown on the untreated or plasma-treated porous silicon. In addition, the expression of several apoptosis genes were suppressed, relative to the untreated or plasma-treated surfaces.     

Comparison of techniques for extraction of isoflavones from the root of Radix Puerariae: Ultrasonic and pressurized solvent extractions

Radix Puerariae (RP), a traditional Chinese medicinal herb, has been used for a variety of disease prevention and treatment purposes. Three isoflavones, puerarin, daidzin and daidzein, isolated from RP are responsible for its broad therapeutic effects. In the present study, we demonstrate the application of three extraction methods, traditional, pressurized solvent extraction (PSE) and ultrasonic techniques, for preparing ethanolic RP extract. A comparison of the three extraction methods showed preferential higher yields of the three major isoflavones when the ultrasonic technique was applied. The extraction yield became higher as the mean size of RP particles decreased while the total accumulated power varied from 20 to 80 MJ at the solid-to-solvent ratios of 1:5 and 1:10 (g/ml). The relationship among accumulated energies, extraction yields and mean particle sizes under different extraction ratios using ultrasound was also discussed. This study proves that using the ultrasonic method should be the most economic way for enhancing the extraction yield of isoflavones-containing herbal extract in a short time with a reduced amount of solvent at a lower temperature.     

A portable electrochemical sensor for caffeine and (-)epigallocatechin gallate based on molecularly imprinted poly(ethylene-co-vinyl alcohol) recognition element

The U.S. Food and Drug Administration allows a maximum of 72 mg of caffeine per 12 oz. serving (6 mg/oz). Consuming 400 mg of caffeine 3 times daily for 7 days may develop sleep disruption effects. However, it is still very hard for people to estimate how much caffeine is intake daily. Moreover, (-)epigallocatechin gallate (EGCG) is studied a potent antioxidant that may have therapeutic properties for anti-aging and cancer. Conventionally, both caffeine and EGCG could be measured by the protocols of high performance liquid chromatography; however, high precision instruments are required. In this work, the caffeine and EGCG are used as the template molecules and imprinted into poly(ethylene-co-vinyl alcohol), EVAL, via solvent evaporation. The EVAL membrane is then used as the sensing element for electrochemical analysis after templates removal. From the cyclic voltammetry measurement of the caffeine, the peak oxidation potential is shifted from 0.36 to 0.46 V when the final concentration of caffeine is from 0.01 to 1 mg/mL, and the highest current density is about 0.18 microA/cm2. The caffeine and EGCG concentrations measured in three real samples are about 0.10-0.13 mg/mL and 0.49-1.74 mg/mL, respectively. This molecularly imprinted polymeric coated electrode is potential employed as a home-care system.     

Sensing of digestive proteins in saliva with a molecularly imprinted poly(ethylene-co-vinyl alcohol) thin film coated quartz crystal microbalance sensor

The quartz crystal microbalance (QCM) has a sensitivity comparable to that of the surface plasmon resonance (SPR) transducer. Molecularly imprinted polymers (MIPs) have a much lower cost than natural antibodies, they are easier to fabricate and more stable, and they exhibit satisfactory recognition ability when integrated onto sensing transducers. Hence, MIP-based QCM sensors have been used to recognize small molecules and, recently, microorganisms, but only a few have been adopted in protein sensing. In this work, a mixed salivary protein and poly(ethylene-co-vinyl alcohol), EVAL, solution is coated onto a QCM chip and a molecularly imprinted EVAL thin film formed by thermally induced phase separation (TIPS). The optimal ethylene mole ratios of the commercially available EVALs for the imprinting of amylase, lipase and lysozyme were found to be 32, 38, and 44 mol %, respectively. Finally, the salivary protein-imprinted EVAL-based QCM sensors were used to detect amylase, lipase and lysozyme in real samples (saliva) and their effectiveness was compared with that of a commercial ARCHITECT ci 8200 chemical analysis system. The limits of detection (LOD) for those salivary proteins were as low as ～pM.     

A Novel Supercritical CO2 Synthesis of Amorphous Hydrous Zirconia Nanoparticles, and Their Calcination to Zirconia

A novel synthesis of amorphous hydrous zirconia nanoparticles was performed in a supercritical carbon dioxide (scCO₂) reverse microemulsion, converting a high concentration of a very inexpensive starting material (zirconyl nitrate hydrate) into a product that was then calcined to yield monoclinic zirconia nanoparticles. The amorphous hydrous zirconia precursor particles were obtained by simply adding a precipitating agent to [Zr⁴⁺_(aq)]/perfluoropolyether/scCO₂. Calcination converts the amorphous hydrous zirconia precursor into the oxide, and the corresponding phase changes that occur were confirmed by differential thermal analysis. Some control of particle size and shape (ellipticity) could be achieved by selecting the reaction pressure from within the range over which stable microemulsions are obtained (13.9–17.3 MPa): a higher reaction pressure yields smaller and more spherical particles. This novel route for the synthesis of zirconia nanoparticles is both "green" (environmentally friendly) and economical.     

Synthesis of Zirconia with Nanoporous Structure by a Supercritical Carbon Dioxide Microemulsion Route

Supercritical carbon dioxide (scCO₂) fluid as a green solvent for processing can markedly reduce the use of organic solvents. Nanoporous clusters of zirconia (ZrO₂) were synthesized in a [Zr⁴⁺](aq)/scCO₂ microemulsion using hydrazine solution as the precipitating agent, and the resulting nanostructures (surface area, morphology) under different reaction temperatures and pressures were determined by BET and TEM. The inter droplet separation of microemulsions increases with the reaction pressure at a fixed temperature, giving different networked nanostructures. The closed pore diameters were in the range of 5–150 nm (mesopores and macropores) at 17.3 MPa and 80°C.     

Stability and characterisation of phospholipid-based curcumin-encapsulated microemulsions

The ternary phase diagram of a curcumin-encapsulated O/W microemulsion system using food-acceptable components, lecithin and Tween 80 as the surfactants and ethyl oleate as the oil phase, was constructed. The stability and characterisation of curcumin in microemulsion were investigated. The results indicated that a composition of curcumin microemulsion (DI water: surfactants (the mole ratio of lecithin/Tween 80 was 0.3): EO = 10:1.7:0.4 in wt ratio) was stable for 2 months with an average diameter of 71.8 ± 2.45 nm, as detected by UV–Vis spectra and diameter distributions. The microemulsion possesses an ability to be diluted with aqueous buffer without destroying its structure for 48 h. A skin permeation study for testing the penetration effect of various curcumin loading in the microemulsions with different particle diameters was also performed and discussed in this contribution.     

Porous Biphasic Calcium Phosphate Granules from Oyster Shell Promote the Differentiation of Induced Pluripotent Stem Cells

Oyster shells are rich in calcium, and thus, the potential use of waste shells is in the production of calcium phosphate (CaP) minerals for osteopathic biomedical applications, such as scaffolds for bone regeneration. Implanted scaffolds should stimulate the differentiation of induced pluripotent stem cells (iPSCs) into osteoblasts. In this study, oyster shells were used to produce nano-grade hydroxyapatite (HA) powder by the liquid-phase precipitation. Then, biphasic CaP (BCP) bioceramics with two different phase ratios were obtained by the foaming of HA nanopowders and sintering by two different two-stage heat treatment processes. The different sintering conditions yielded differences in structure and morphology of the BCPs, as determined by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) surface area analysis. We then set out to determine which of these materials were most biocompatible, by co-culturing with iPSCs and examining the gene expression in molecular pathways involved in self-renewal and differentiation of iPSCs. We found that sintering for a shorter time at higher temperatures gave higher expression levels of markers for proliferation and (early) differentiation of the osteoblast. The differences in biocompatibility may be related to a more hierarchical pore structure (micropores within macropores) obtained with briefer, high-temperature sintering.     

Synthesis of spherical zirconia by reverse emulsion precipitation

Spherical ZrO₂ microparticles were prepared in a three-phase reactor by mixing two water-in-oil emulsions with normal heptane as oil phase and aqueous solutions of zirconium oxyacetate and ammonia as water phases, respectively. The principal factors that influenced the stability of emulsion were investigated, including the surfactant type, the volume of w/o, and the concentration of zirconium ion. In this work, four anion surfactants were tested, including Span 85, Arlacel 83, Span 80 and Span 40. The most stable reverse emulsions were obtained with the surfactant Span 40. When w/o volume ratio was kept 1/100 using Span 40 or Span 80 as a surfactant, the ZrO₂ microparticles with spherical morphology were successfully prepared in the reverse emulsions at various Zr⁴⁺ concentrations (from 0.5 M to 3 M). The particle sizes of ZrO₂ are smaller for Span 40 as compared with Span 80 on the same Zr⁴⁺ concentrations. The crystalline phase of the ZrO₂ powders after calcination at 750 °C for 2 h was tetragonal.