Dynamic Exergy Method for Evaluating the Control and Operation of Oxy-Combustion Boiler Island Systems

Exergy-based methods are widely applied to assess the performance of energy conversion systems; however, these methods mainly focus on a certain steady-state and have limited applications for evaluating the control impacts on system operation. To dynamically obtain the thermodynamic behavior and reveal the influences of control structures, layers and loops, on system energy performance, a dynamic exergy method is developed, improved, and applied to a complex oxy-combustion boiler island system for the first time. The three most common operating scenarios are studied, and the results show that the flow rate change process leads to less energy consumption than oxygen purity and air in-leakage change processes. The variation of oxygen purity produces the largest impact on system operation, and the operating parameter sensitivity is not affected by the presence of process control. The control system saves energy during flow rate and oxygen purity change processes, while it consumes energy during the air in-leakage change process. More attention should be paid to the oxygen purity change because it requires the largest control cost. In the control system, the supervisory control layer requires the greatest energy consumption and the largest control cost to maintain operating targets, while the steam control loops cause the main energy consumption

Tailor-Made Core–Shell CaO/TiO₂–Al₂O₃ Architecture as a High-Capacity and Long-Life CO₂ Sorbent

CaO-based sorbents are widely used for CO₂ capture, steam methane reforming, and gasification enhancement, but the sorbents suffer from rapid deactivation during successive carbonation/calcination cycles. This research proposes a novel self-assembly template synthesis (SATS) method to prepare a hierarchical structure CaO-based sorbent, Ca-rich, Al₂O₃-supported, and TiO₂-stabilized in a core–shell microarchitecture (CaO/TiO₂–Al₂O₃). The cyclic CO₂ capture performance of CaO/TiO₂–Al₂O₃ is compared with those of pure CaO and CaO/Al₂O₃. CaO/TiO₂–Al₂O₃ sorbent achieved superior and durable CO₂ capture capacity of 0.52 g CO₂/g sorbent after 20 cycles under the mild calcination condition and retained a high-capacity and long-life performance of 0.44 g CO₂/g sorbent after 104 cycles under the severe calcination condition, much higher than those of CaO and CaO/Al₂O₃. The microstructure characterization of CaO/TiO₂–Al₂O₃ confirmed that the core–shell structure of composite support effectively inhibited the reaction between active component (CaO particles) and main support (Al₂O₃ particles) by TiO₂ addition, which contributed to its properties of high reactivity, thermal stability, mechanical strength, and resistance to agglomeration and sintering

One-Step Synthesis of CuO–Cu₂O Heterojunction by Flame Spray Pyrolysis for Cathodic Photoelectrochemical Sensing of l‑Cysteine

CuO–Cu₂O heterojunction was synthesized via a one-step flame spray pyrolysis (FSP) process and employed as photoactive material in construction of a photoelectrochemical (PEC) sensing device. The surface analysis showed that CuO–Cu₂O nanocomposites in the size less than 10 nm were formed and uniformly distributed on the electrode surface. Under visible light irradiation, the CuO–Cu₂O-coated electrode exhibited admirable cathodic photocurrent response, owing to the favorable property of the CuO–Cu₂O heterojunction such as strong absorption in the visible region and effective separation of photogenerated electron–hole pairs. On the basis of the interaction of l-cysteine (l-Cys) with Cu-containing compounds via the formation of Cu–S bond, the CuO–Cu₂O was proposed as a PEC sensor for l-Cys detection. A declined photocurrent response of CuO–Cu₂O to addition of l-Cys was observed. Influence factors including CuO–Cu₂O concentration, coating amount of CuO–Cu₂O, and applied bias potential on the PEC response toward l-Cys were optimized. Under optimum conditions, the photocurrent of the proposed sensor was linearly declined with increasing the concentration of l-Cys from 0.2 to 10 μM, with a detection limit (3S/N) of 0.05 μM. Moreover, this PEC sensor displayed high selectivity, reproducibility, and stability. The potential applicability of the proposed PEC sensor was assessed in human urine samples

Controlling Acetylene Adsorption and Reactions on Pt–Sn Catalytic Surfaces

Acetylene reactivity as a function of Sn concentration on Pt catalytic surfaces was studied by comparing adsorption and reactions of regular and deuterated acetylene at 90–1000 K on three surfaces, Pt(111), Pt₃Sn/Pt­(111), and Pt₂Sn/Pt­(111), using high-resolution electron energy loss spectroscopy, temperature-programmed desorption, and density functional theory calculations. The strongly adsorbed di-σ/π-bonded acetylene species, which dominate on pure Pt, were not detected on the Pt–Sn surfaces. The presence of Sn is also shown to suppress acetylene decomposition and, as a result, to maintain adsorbed acetylene in the molecular form as weakly adsorbed π- and di-σ-bonded species. The destabilization of adsorbed acetylene makes associative reactions with the formation of dimers (C₄ hydrocarbons) and trimers (benzene) progressively more energetically favorable with increasing Sn concentration. Acetylene adsorption modes and reactions on Pt catalytic surfaces can, therefore, be controlled with Sn alloying. The concentration of Sn needs to be an optimal level for catalytic activity since all hydrocarbon species bind preferentially only to Pt sites

CD68 can be found in a dome-like pattern in osteoclasts cultured on bovine cortical bone slices.

<p>(A) BMMs were seeded onto bone slices with 44 ng/mL M-CSF and 100 ng/mL RANKL and differentiated into osteoclasts over 4 days. Cells were fixed with 4% paraformaldehyde/PBS and stained with Alexa-488-conjugated phalloidin (actin, green), Hoescht (nuclei, blue), and either anti-CD68 (CD68, red) or rat non-immune IgG_2a (IgG_2a Merge) antibody followed by Alexa-647-conjugated anti-Rat IgG. Scale bars for CD68 staining are 40μm; scale bar for IgG_2a staining is 20μm. Images are representative of 3 independent experiments. (B) Enlarged merge image from A. * and + indicate corresponding XZ and YZ cross sectional images, respectively. Scale bar is 40μm. Image is representative of 3 independent experiments. (C) 3-D reconstruction of osteoclast cross sectioned in B with actin in green, nuclei in blue, and CD68 in red.</p

BMMs from CD68^−/− mice lack expression of CD68.

<p>(A) Vector diagram with a neomycin phosphotransferase expression cassette (PGK-NEO) flanked by sequences with homology to targeted genomic sequence. A thymidine kinase expression cassette (PGK-TK) lies outside the homology region of vector. (B) Structure of targeted wild type allele. A southern blot probe can hybridize to a genomic sequence outside of the homology region. P1 and P2 are primers that specifically amplify the sequence of CD68 targetted for replacement. (C) Recombined allele with exons 1 and 2 of CD68 gene replaced with PGK-NEO. Properly targeted recombined alleles do not contain the thymidine kinase expression cassette. P3 and P4 are primers that specifically amplify a region of PGK-NEO. (D) Tail tip extracts from each of three resultant genotypes were subjected to genotyping PCR using P1, P2, P3, and P4. Each genotype produced a unique pattern of PCR products. (E) Lysates from BMMs from each genotype cultured with 220 ng/mL M-CSF were immunoblotted with antibodies against CD68 and α-Tubulin. While expression of CD68 was seen in +/+ and +/− BMMs, no CD68 could be detected in lysates from −/− BMMs.</p

CD68^−/− osteoclasts do not efficiently resorb bone.

<p>BMMs from CD68^+/+, ^+/−, and ^−/− mice were seeded onto bovine cortical bone slices and differentiated into osteoclasts over 4 days. Differentiated osteoclasts were allowed to resorb the slices for an additional 3 days. (A) Representative images of resorbed bone slices generated using laser scanning confocal microscopy. A pit from each image is marked with an arrow. Scale bars are 70μm. (B) Quantification of resorbed area. Data represented as means + standard deviation. *, p<.001. 3 visual fields each from 3 separately resorbed bone slices were assessed. Data presented are means + standard deviation. Images and data are representative of 2 independent experiments.</p

CD68 is expressed by macrophages and osteoclasts.

<p>(A) CD68 and β-actin expression in mouse bone marrow suspension cells treated with 44 ng/mL M-CSF +/− 100 ng/mL RANKL for indicated days (d). M-CSF increases expression of CD68 in a time dependant manner, and RANKL ligand induces an accelerated gel migration rate. Image is representative of 3 independent experiments. Quantification of relative band density is aggregate of 3 independent experiments; data shown is mean + standard deviation. (B) CD68 and β-actin expression in RAW264.7 cells with or without 100 ng/mL RANKL treatment for indicated times. RAW264.7 cells have constitutive M-CSF-stimulated signaling and continuous expression of CD68. RANKL induces similar changes in gel migration as those seen in primary macrophages. Image is representative of 3 independent experiments. Quantification of relative band density is aggregate of 3 independent experiments; data shown is mean + standard deviation. (C) Flow cytometry histograms of BMMs with 3-day treatments of 44 ng/mL M-CSF +/– 100 ng/mL RANKL with (Total) and without (Surface) permeablization with .5% saponin. CD68 can be detected on the surface of BMMs, and neither surface nor total detectible levels of CD68 are altered by addition of RANKL. Image is representative of 2 independent experiments.</p

CD68^−/− have abnormal morphology.

<p>(A) Prior to TRAP staining, osteoclasts of all three genotypes were of relatively similar size. CD68^−/− osteoclasts demonstrated intracellular vacuole-like structures that were not present to such an extent in CD68-expressing cells. Scale bars are 100μm. Images are representative of 3 independent experiments. (B) During the fixation process (fixative: 25 mL citrate solution [18 mM citric acid, 9 mM sodium citrate, 12 mM sodium chloride, pH 3.6], 68 mL acetone, 8 mL 37% formaldehyde), many CD68^−/− osteoclasts were reduced in size and partially detached from the culture substrate resulting in a smaller size following TRAP staining. Scale bars are 200μm. Images are representative of 3 independent experiments.</p

Mouse Birth Ratios.

<p>Mouse Birth Ratios.</p