Carbon Dots-Mediated Fluorescent Scaffolds: Recent Trends in Image-Guided Tissue Engineering Applications

Regeneration of damaged tissues or organs is one of the significant challenges in tissue engineering and regenerative medicine. Many researchers have fabricated various scaffolds to accelerate the tissue regeneration process. However, most of the scaffolds are limited in clinical trials due to scaffold inconsistency, non-biodegradability, and lack of non-invasive techniques to monitor tissue regeneration after implantation. Recently, carbon dots (CDs) mediated fluorescent scaffolds are widely explored for the application of image-guided tissue engineering due to their controlled architecture, light-emitting ability, higher chemical and photostability, excellent biocompatibility, and biodegradability. In this review, we provide an overview of the recent advancement of CDs in terms of their different synthesis methods, tunable physicochemical, mechanical, and optical properties, and their application in tissue engineering. Finally, this review concludes the further research directions that can be explored to apply CDs in tissue engineering.     

Microstructural and Defect Analysis of Metal Nanoparticles in Functional Catalysts by Diffraction and Electron Microscopy: The Cu/ZnO Catalyst for Methanol Synthesis

The application of different methods for a microstructural analysis of functional catalysts is reported for the example of different Cu/ZnO-based methanol synthesis catalysts. Transmission electron microscopy and diffraction were used as complementary techniques to extract information on the size and the defect concentration of the Cu nano-crystallites. The results, strengths and limitations of the two techniques and of different evaluation methods for line profile analysis of diffraction data including Rietveld-refinement, Scherrer- and (modified) Williamson–Hall-analyses, single peak deconvolution and whole powder pattern modeling are compared and critically discussed. It was found that in comparison with a macrocrystalline pure Cu sample, the catalysts were not only characterized by a smaller crystallite size, but also by a high concentration of lattice defects, in particular stacking faults. Neutron diffraction was introduced as a valuable tool for such analysis, because of the larger number of higher-order diffraction peaks that can be detected with this method. An attempt is reported to quantify the different types of defects for a selected catalyst.     

High-intensity laser-driven particle and electromagnetic wave sources for science, industry, and medicine

We simultaneously observed both the fast proton generation and terahertz (THz) radiation in the laser pulse interaction with a thin-foil target.The maximum proton energy of ～2.3 MeV and an intense THz radiation were observed at the pulse duration of ～30fs.We also measured the proton beam and UV harmonics from a thin-foil target by changing the laser pulse duration.In the case of the ～500 fs, peaks of UV harmonics up to fourth order appeared.This unique combination of the multiple beams will provide useful applications such as pump-probe experiments.     

Modified gold surfaces by 6-(ferrocenyl)hexanethiol/dendrimer/gold nanoparticles as a platform for the mediated biosensing applications

An electrochemical biosensor mediated by using 6-(Ferrocenyl) hexanethiol (FcSH) was fabricated by construction of gold nanoparticles (AuNPs) on the surface of polyamidoamine dendrimer (PAMAM) modified gold electrode. Glucose oxidase (GOx) was used as a model enzyme and was immobilized onto the gold surface forming a self assembled monolayer via FcSH and cysteamine. Cyclic voltammetry and amperometry were used for the characterization of electrochemical response towards glucose substrate. Following the optimization of medium pH, enzyme loading, AuNP and FcSH amount, the linear range for the glucose was studied and found as 1.0 to 5.0 mM with the detection limit (LOD) of 0.6 mM according to S/N = 3. Finally, the proposed Au/AuNP/(FcSH + Cyst)/PAMAM/GOx biosensor was successfully applied for the glucose analysis in beverages, and the results were compared with those obtained by HPLC.     

Vanadium incorporated high surface area MCM-41 catalysts

High surface area MCM-41 (1452 m²/g) and V-MCM-41 materials were synthesized by a direct hydrothermal synthesis method. Characteristic XRD patterns, SEM and AFM photographs indicated no significant change in the morphology of MCM-41 by incorporation of vanadium. XPS and EDS results proved that incorporation of vanadium into the MCM-41 structure was successfully achieved when vanadyl sulfate hydrate was used as the vanadium source. However, use of ammonium vanadate as the vanadium source was not equally successful.     

Improving retouched Bloom filter for trading off selected false positives against false negatives

Where distributed agents must share voluminous set membership information, Bloom filters provide a compact, though lossy, way for them to do so. Numerous recent networking papers have examined the trade-offs between the bandwidth consumed by the transmission of Bloom filters, and the error rate, which takes the form of false positives. This paper is about the retouched Bloom filter (RBF). An RBF is an extension that makes the Bloom filter more flexible by permitting the removal of false positives, at the expense of introducing false negatives, and that allows a controlled trade-off between the two. We analytically show that creating RBFs through a random process decreases the false positive rate in the same proportion as the false negative rate that is generated. We further provide some simple heuristics that decrease the false positive rate more than the corresponding increase in the false negative rate, when creating RBFs. These heuristics are more effective than the ones we have presented in prior work. We further demonstrate the advantages of an RBF over a Bloom filter in a distributed network topology measurement application. We finally discuss several networking applications that could benefit from RBFs instead of standard Bloom filters.     

Soda Ash Production from Trona in a Spray Dryer

Production of soda ash from Trona solution was achieved in a spray dryer reactor. Fractional conversion of NaHCO₃ reached to values close to unity in this unit within a residence time of less than a second. Results indicated that above 140°C, heat transfer limitations played a significant role on the calcination process taking place in the spray dryer. Equilibrium limitations may become important only at very low temperatures and at high CO₂ and H₂O partial pressures. Results obtained in the spray dryer and from the thermal gravimetric analysis of Trona crystals agreed well. It was also shown that the predictions of the unreacted core model are in good agreement with the kinetic data. © 1997 SCI.     

Preparation and characterization of palladium-plated porous glass for hydrogen enrichment

In this study, cylindrical porous glass tablets were plated by palladium using electroless plating technique. Hypophosphite and Co(II) complexes were used as reducing agents in the prepared plating baths. Experiments were carried out in an especially designed glass vessel in which helium gas was continuously bubbled through the solution to create uniform concentration and to remove hydrogen gas from the surface for the case of hypophosphite-based procedure. XRF analysis of the upper layer of the composite membrane prepared by the hypophosphite-based bath showed a Pd/Si ratio of 4.6. SEM photographs indicated impregnation of Pd into the substrate upto 200 μm. However, the thickness of the dense Pd layer was only about 15 μm. SEM photographs and XRF results showed that hypophosphite-based bath was much more successful than the Co(II) complex-bath in Pd plating. Permeation experiments carried out at different temperatures showed that the contribution of surface diffusion to the permeation was significant at low temperatures and solution–diffusion mechanism was not important in the 40–200 °C temperature range for these membranes. The selectivity ratio for H₂/N₂ was found to be about 7 at 200 °C.     

Determinants of Lipid Domain Size

Lipid domains less than 200 nm in size may form a scaffold, enabling the concerted function of plasma membrane proteins. The size-regulating mechanism is under debate. We tested the hypotheses that large values of spontaneous monolayer curvature are incompatible with micrometer-sized domains. Here, we used the transition of photoswitchable lipids from their cylindrical conformation to a conical conformation to increase the negative curvature of a bilayer-forming lipid mixture. In contrast to the hypothesis, pre-existing micrometer-sized domains did not dissipate in our planar bilayers, as indicated by fluorescence images and domain mobility measurements. Elasticity theory supports the observation by predicting the zero free energy gain for splitting large domains into smaller ones. It also indicates an alternative size-determining mechanism: The cone-shaped photolipids reduce the line tension associated with lipid deformations at the phase boundary and thus slow down the kinetics of domain fusion. The competing influence of two approaching domains on the deformation of the intervening lipids is responsible for the kinetic fusion trap. Our experiments indicate that the resulting local energy barrier may restrict the domain size in a dynamic system.     

Steam reforming of ethanol with zirconia incorporated mesoporous silicate supported catalysts

Steam reforming of ethanol is a promising route for the production of high purity hydrogen. Ni impregnated zirconia, with high chemical and thermal stability and high water adsorption-dissociation capability is an attractive catalyst for this reaction. In the present study, mesoporous zirconia and high surface area zirconia/silicate structured materials, such as Zr-SBA-15 and Zr-MCM-41, were synthesized following hydrothermal routes, using different surfactants as the structure directing templates. Surface area values of Ni impregnated mesoporous Zr-SBA-15 and Zr-MCM-41 catalysts with molar Zr/Si ratios of 0.13 and 0.45 were 515 and 338 m²/g, respectively. Ethanol reforming tests performed with these catalysts, in the temperature range of 550–650 °C, proved the potential of these materials to achieve very high hydrogen yields, over 90% of the maximum yield value of 6 mol per mole of ethanol reacted. Type of support material, Ni distribution and cluster size over the catalyst, reaction temperature and steam to ethanol ratio were found to have strong influence on coke formation and stability of hydrogen yield.