Oxidative dehydrogenation of ethane over a monolith coated by molybdenum-vanadium-niobium mixed-oxide catalyst

Oxidative dehydrogenation of ethane to ethylene was investigated using Mo 0.71 V 0.21 Nb 0.08 mixed-oxide catalyst, in powder form and coated over a monolith. At 570°C and with a feed stream containing an O 2 /C 2 H 6 mole ratio of one, ethylene selectivity value reaching to 96% was obtained at a conversion level of about 5% with the monolith-supported catalyst. DRIFTS studies indicated the presence of adsorbed ethoxide species. The proposed reaction scheme for the production of ethylene includes the elimination of g -hydrogen of adsorbed species by the lattice oxygen.     

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.     

The Role of Glycogen Synthase Kinase-3 in the Regulation of Ribosome Biogenesis in Rat Soleus Muscle under Disuse Conditions

It is well-established that prolonged exposure to real or simulated microgravity/disuse conditions results in a significant reduction in the rate of muscle protein synthesis (PS) and loss of muscle mass. Muscle protein synthesis is largely dependent upon translational capacity (ribosome content), the regulation of which is poorly explored under conditions of mechanical unloading. Glycogen synthase kinase-3 (GSK-3) (a negative regulator of PS) is known to be activated in rat soleus muscle under unloading conditions. We hypothesized that inhibition of GSK-3 activity under disuse conditions (hindlimb suspension, HS) would reduce disuse-induced downregulation of ribosome biogenesis in rat soleus muscle. Wistar rats were randomly divided into four groups: (1) vivarium control (C), (2) vivarium control + daily injections (4 mg/kg) of AR-A014418 (GSK-3 inhibitor) for 7 days, (3) 7-day HS, (4) 7-day HS + daily injections (4 mg/kg) of AR-A014418. GSK-3beta and glycogen synthase 1 (GS-1) phosphorylation levels were measured by Western-blotting. The key markers of ribosome biogenesis were assessed via agarose gel-electrophoresis and RT-PCR. The rate of muscle PS was assessed by puromycin-based SUnSET method. As expected, 7-day HS resulted in a significant decrease in the inhibitory Ser9 GSK-3beta phosphorylation and an increase in GS-1 (Ser641) phosphorylation compared to the C group. Treatment of rats with GSK-3 inhibitor prevented HS-induced increase in GS1 (Ser641) phosphorylation, which was indicative of GSK-3 inhibition. Administration of GSK-3 inhibitor partly attenuated disuse-induced downregulation of c-Myc expression as well as decreases in the levels of 45S pre-rRNA and 18S + 28S rRNAs. These AR-A014418-induced alterations in the markers of ribosome biogenesis were paralleled with partial prevention of a decrease in the rate of muscle PS. Thus, inhibition of GSK-3 during 7-day HS is able to partially attenuate the reductions in translational capacity and the rate of PS in rat soleus muscle.     

OXIDATIVE DEHYDROGENATION OF ETHANE OVER A MONOLITH COATED BY MOLYBDENUM-VANADIUM-NIOBIUM MIXED-OXIDE CATALYST

Oxidative dehydrogenation of ethane to ethylene was investigated using Mo 0.71 V 0.21 Nb 0.08 mixed-oxide catalyst, in powder form and coated over a monolith. At 570°C and with a feed stream containing an O 2 /C 2 H 6 mole ratio of one, ethylene selectivity value reaching to 96% was obtained at a conversion level of about 5% with the monolith-supported catalyst. DRIFTS studies indicated the presence of adsorbed ethoxide species. The proposed reaction scheme for the production of ethylene includes the elimination of β-hydrogen of adsorbed species by the lattice oxygen.