Fabrication of Au@CaCO₃ Nanoparticles by in Situ Mineralization in Hydrogel Microspheres

Fabrication of Au@CaCO3 Nanoparticles by in Situ Mineralization in Hydrogel Microsphere

Improving Combustion Characteristics and NO_<i>x</i> Emissions of a Down-Fired 350 MW_e Utility Boiler with Multiple Injection and Multiple Staging

Within a Mitsui Babcock Energy Limited down-fired pulverized-coal 350 MWe utility boiler, in situ experiments were performed, with measurements taken of gas temperatures in the burner and near the right-wall regions, and of gas concentrations (O2 and NO) from the near-wall region. Large combustion differences between zones near the front and rear walls and particularly high NOx emissions were found in the boiler. With focus on minimizing these problems, a new technology based on multiple-injection and multiple-staging has been developed. Combustion improvements and NOx reductions were validated by investigating three aspects. First, numerical simulations of the pulverized-coal combustion process and NOx emissions were compared in both the original and new technologies. Good agreement was found between simulations and in situ measurements with the original technology. Second, with the new technology, gas temperature and concentration distributions were found to be symmetric near the front and rear walls. A relatively low-temperature and high-oxygen-concentration zone formed in the near-wall region that helps mitigate slagging in the lower furnace. Third, NOx emissions were found to have decreased by as much as 50%, yielding a slight decrease in the levels of unburnt carbon in the fly ash

Overall Evaluation of Combustion and NO_<i>x</i> Emissions for a Down-Fired 600 MW_e Supercritical Boiler with Multiple Injection and Multiple Staging

To achieve significant reductions in NO_<i>x</i> emissions and to eliminate strongly asymmetric combustion found in down-fired boilers, a deep-air-staging combustion technology was trialed in a down-fired 600 MW_e supercritical utility boiler. By performing industrial-sized measurements taken of gas temperatures and species concentrations in the near wing-wall region, carbon in fly ash and NO_<i>x</i> emissions at various settings, effects of overfire air (OFA) and staged-air damper openings on combustion characteristics, and NO_<i>x</i> emissions within the furnace were experimentally determined. With increasing the OFA damper opening, both fluctuations in NO_<i>x</i> emissions and carbon in fly ash were initially slightly over OFA damper openings of 0–40% but then lengthened dramatically in openings of 40–70% (i.e., NO_<i>x</i> emissions reduced sharply accompanied by an apparent increase in carbon in fly ash). Decreasing the staged-air declination angle clearly increased the combustible loss but slightly influenced NO_<i>x</i> emissions. In comparison with OFA, the staged-air influence on combustion and NO_<i>x</i> emissions was clearly weaker. Only at a high OFA damper opening of 50%, the staged-air effect was relatively clear, i.e., enlarging the staged-air damper opening decreased carbon in fly ash and slightly raised NO_<i>x</i> emissions. By sharply opening the OFA damper to deepen the air-staging conditions, although NO_<i>x</i> emissions could finally reduce to 503 mg/m³ at 6% O₂ (i.e., an ultralow NO_<i>x</i> level for down-fired furnaces), carbon in fly ash jumped sharply to 15.10%. For economical and environment-friendly boiler operations, an optimal damper opening combination (i.e., 60%, 50%, and 50% for secondary air, staged-air, and OFA damper openings, respectively) was recommended for the furnace, at which carbon in fly ash and NO_<i>x</i> emissions attained levels of about 10% and 850 mg/m³ at 6% O₂, respectively

An Accessible Protocol for Solid-Phase Extraction of N‑Linked Glycopeptides through Reductive Amination by Amine-Functionalized Magnetic Nanoparticles

In light of the significance of glycosylation for wealthy biological events, it is important to prefractionate glycoproteins/glycopeptides from complex biological samples. Herein, we reported a novel protocol of solid-phase extraction of glycopeptides through a reductive amination reaction by employing the easily accessible 3-aminopropyltriethoxysilane (APTES)-functionalized magnetic nanoparticles. The amino groups from APTES, which were assembled onto the surface of the nanoparticles through a one-step silanization reaction, could conjugate with the aldehydes from oxidized glycopeptides and, therefore, completed the extraction. To the best of our knowledge, this is the first example of applying the reductive amination reaction into the isolation of glycopeptides. Due to the elimination of the desalting step, the detection limit of glycopeptides was improved by 2 orders of magnitude, compared to the traditional hydrazide chemistry-based solid phase extraction, while the extraction time was shortened to 4 h, suggesting the high sensitivity, specificity, and efficiency for the extraction of N-linked glycopeptides by this method. In the meantime, high selectivity toward glycoproteins was also observed in the separation of Ribonuclease B from the mixtures contaminated with bovine serum albumin. What’s more, this technique required significantly less sample volume, as demonstrated in the successful mapping of glycosylation of human colorectal cancer serum with the sample volume as little as 5 μL. Because of all these attractive features, we believe that the innovative protocol proposed here will shed new light on the research of glycosylation profiling

pH-Responsive Capsules Derived from Nanocrystal Templating

In the current work we demonstrate a facile and versatile way to create hydrophilic polymeric capsules by integration of Au nanocrystal templating, surface-initiated atom-transfer radical polymerization, and selective chemical cross-linking of polymer shells. Capsules of the homopolymer of 2-(dimethylamino)ethyl methacrylate and its copolymers with 2-(diethylamino)ethyl methacrylate and poly(ethylene glycol) methyl ether methacrylate were constructed. They swell at low pH and shrink at high pH. On the basis of the pH sensitivity of the resulting capsules, encapsulation and release of a drug model, rhodamine 6G, were realized. Furthermore, by cleaving Au−S bonds between Au cores and polymer shells, capsules containing free Au cores were generated, paving a simple pathway to introduce more functionality to the polymeric capsules

Plasmonic Vesicles of Amphiphilic Gold Nanocrystals: Self-Assembly and External-Stimuli-Triggered Destruction

We have developed a new class of plasmonic vesicular nanostructures assembled from amphiphilic gold nanocrystals with mixed polymer brush coatings. One major finding is that the integration of gold nanocrystals (nanoparticles and nanorods) with two types of chemically distinct polymer grafts, which are analogous to block copolymers as a whole, creates a new type of hybrid building block inheriting the amphiphilicity-driven self-assembly of block copolymers to form vesicular structures and the plasmonic properties of the nanocrystals. In contrast to other vesicular structures, the disruption of the plasmonic vesicles can be triggered by stimulus mechanisms inherent to either the polymer or the nanocrystal. Recent advances in nanocrystal synthesis and controlled surface-initiated polymerization have opened a wealth of possibilities for expanding this concept to other types of nanocrystals and integrating different types of nanocrystals into multifunctional vesicles. The development of multifunctional vesicles containing stimuli-responsive polymers could enable their broader applications in biosensing, multimodality imaging, and theragnostic nanomedicine

Quantum Dots with Phenylboronic Acid Tags for Specific Labeling of Sialic Acids on Living Cells

Sialic acids with a nine-carbon backbone are commonly found at the terminal position of the glycans structures on cell membranes. The unique distribution and ubiquitous existence of sialic acid on the cell membrane make them important mediators in various biological and pathological processes. We report a new class of imaging probes based on semiconductor quantum dots with small molecular phenylboronic acid tags for highly specific and efficient labeling of sialic acid on living cells. Our results have shown that the use of these probes enables one-step labeling and continuous tracking of the cell surface sialic acid moieties without any pretreatment of living cells. The one-step procedure with fast binding kinetics and the biocompatibility of these probes make it an ideal noninvasive technology for living cell imaging. We also find that the labeled sialic acids undergo quick internalization shortly after surface binding via endocytosis and eventually distribute in the perinuclear region. This distribution pattern is consistent with the notion that sialylated glycoproteins are populated on cell membranes and recycled through the vesicular exocytotic and endocytic pathways. The superior photostability and brightness of quantum dots enable quantitative analysis of the diffusion dynamics of sialic acids, which has been a significant challenge for glycan imaging

Influence of Staged-Air on Airflow, Combustion Characteristics and NO_<i>x</i> Emissions of a Down-Fired Pulverized-Coal 300 MW_e Utility Boiler with Direct Flow Split Burners

Cold airflow experiments were conducted to investigate the aerodynamic field in a small-scale furnace of a down-fired pulverized-coal 300 MWe utility boiler arranged with direct flow split burners enriched by cyclones. By increasing the staged-air ratio, a deflected flow field appeared in the lower furnace; larger staged-air ratios produced larger deflections. Industrial-sized experiments on a full-scale boiler were also performed at different staged-air damper openings with measurements taken of gas temperatures in the burner region and near the right-side wall, wall heat fluxes, and gas components (O2, CO, and NOx) in the near-wall region. Combustion was unstable at staged-air damper openings below 30%. For openings of 30% and 40%, late ignition of the pulverized coal developed and large differences arose in gas temperatures and heat fluxes between the regions near the front and rear walls. In conjunction, carbon content in the fly ash was high and boiler efficiency was low with high NOx emission above 1200 mg/m3 (at 6% O2 dry). For fully open dampers, differences in gas temperatures and heat fluxes, carbon in fly ash and NOx emission decreased yielding an increase in boiler efficiency. The optimal setting is fully open staged-air dampers

Quantum Dots with Phenylboronic Acid Tags for Specific Labeling of Sialic Acids on Living Cells

Sialic acids with a nine-carbon backbone are commonly found at the terminal position of the glycans structures on cell membranes. The unique distribution and ubiquitous existence of sialic acid on the cell membrane make them important mediators in various biological and pathological processes. We report a new class of imaging probes based on semiconductor quantum dots with small molecular phenylboronic acid tags for highly specific and efficient labeling of sialic acid on living cells. Our results have shown that the use of these probes enables one-step labeling and continuous tracking of the cell surface sialic acid moieties without any pretreatment of living cells. The one-step procedure with fast binding kinetics and the biocompatibility of these probes make it an ideal noninvasive technology for living cell imaging. We also find that the labeled sialic acids undergo quick internalization shortly after surface binding via endocytosis and eventually distribute in the perinuclear region. This distribution pattern is consistent with the notion that sialylated glycoproteins are populated on cell membranes and recycled through the vesicular exocytotic and endocytic pathways. The superior photostability and brightness of quantum dots enable quantitative analysis of the diffusion dynamics of sialic acids, which has been a significant challenge for glycan imaging