Supracrystals of <i>N</i>‑Heterocyclic Carbene-Coated Au Nanocrystals

Controlling the generation of organized 3D assemblies of individual nanocrystals, called supracrystals, as well as their properties, is an important challenge for the design of new materials in which the coating agent plays a major role. We present herein a new generation of structured fcc Au supracrystals made of <i>N</i>-heterocyclic carbene (NHC)-coated Au nanocrystals. The 3D assemblies were achieved by using benzimidazole-derived NHCs tailored with long alkyl chains at different positions. The average size of the nanocrystal precursors (4, 5, or 6 nm) and their ability to self-assemble were found to be dependent on the length, orientation, and number of alkyl chains on the NHC. Thick and large supracrystal domains were obtained from 5 nm Au nanocrystals coated with NHCs substituted by C14 alkyl chains on the nitrogen atoms. Here, the geometry of both the C_carbene–Au and N–C_alkyl bonds induces a specific orientation of the alkyl chains, different from that of alkylthiols, resulting in Au surface covering by the chains. However, the edge-to-edge distances in the supracrystals suggest that the supracrystals are stabilized by interdigitation of neighboring nanocrystals alkyl chains, whose terminal part must point outward with the appropriate geometry

Two-Dimensional PC-SAFT-DFT Adsorption Models for Carbon Slit-Shaped Pores with Surface Energetical Heterogeneity and Geometrical Corrugation

Studying the effects of surface curvature and energetic heterogeneity on adsorption on carbon surfaces has aroused great interest. Utilizing the PC-SAFT-DFT model may be a promising approach for it. However, efficient algorithms are needed to obtain the two-dimensional (2D) PC-SAFT-DFT calculation results efficiently. In this work, first, the Chebyshev pseudospectral collocation method was extended to 2D PC-SAFT-DFT calculation with complex boundary conditions. In addition, an efficient approach to calculate the matrices required in the Chebyshev pseudospectral collocation method has been proposed which significantly reduces the computation time. Based on the accelerated PC-SAFT-DFT program, a preliminary study of the effects of the surface curvature and energetic heterogeneity for pure and mixed gas adsorption was conducted

Protective Effects of Bifidobacterium on Intestinal Barrier Function in LPS-Induced Enterocyte Barrier Injury of Caco-2 Monolayers and in a Rat NEC Model

<div><p>Zonulin protein is a newly discovered modulator which modulates the permeability of the intestinal epithelial barrier by disassembling intercellular tight junctions (TJ). Disruption of TJ is associated with neonatal necrotizing enterocolitis (NEC). It has been shown bifidobacterium could protect the intestinal barrier function and prophylactical administration of bifidobacterium has beneficial effects in NEC patients and animals. However, it is still unknown whether the zonulin is involved in the gut barrier dysfunction of NEC, and the protective mechanisms of bifidobacterium on intestinal barrier function are also not well understood. The present study aims to investigate the effects of bifidobacterium on intestinal barrier function, zonulin regulation, and TJ integrity both in LPS-induced enterocyte barrier injury of Caco-2 monolayers and in a rat NEC model. Our results showed bifidobacterium markedly attenuated the decrease in transepithelial electrical resistance and the increase in paracellular permeability in the Caco-2 monolayers treated with LPS (<i>P</i> < 0.01). Compared with the LPS group, bifidobacterium significantly decreased the production of IL-6 and TNF-α (<i>P</i> < 0.01) and suppressed zonulin release (<i>P</i> < 0.05). In addition, bifidobacterium pretreatment up-regulated occludin, claudin-3 and ZO-1 expression (<i>P</i> < 0.01) and also preserved these proteins localization at TJ compared with the LPS group. In the in vivo study, bifidobacterium decreased the incidence of NEC from 88 to 47% (<i>P</i> < 0.05) and reduced the severity in the NEC model. Increased levels of IL-6 and TNF-α in the ileum of NEC rats were normalized in bifidobacterium treated rats (<i>P</i> < 0.05). Moreover, administration of bifidobacterium attenuated the increase in intestinal permeability (<i>P</i> < 0.01), decreased the levels of serum zonulin (<i>P</i> < 0.05), normalized the expression and localization of TJ proteins in the ileum compared with animals with NEC. We concluded that bifidobacterium may protect against intestinal barrier dysfunction both in vitro and in NEC. This protective effect is associated with inhibition of proinflammatory cytokine secretion, suppression of zonulin protein release and improvement of intestinal TJ integrity.</p></div

Bifidobacterium reduced the severity and incidence of NEC in a rat NEC model.

<p><b>(A)</b> Body weight changes. *<i>P</i> < 0.01 vs the control group, ^#<i>P</i> < 0.01 vs the NEC group, n = 9–11 animals per group. Three independent experiments were performed in duplicate. <b>(B)</b> Macroscopic appearance of the gastrointestinal tract. In rat pups with NEC, dilation, significant hemorrhage, and discoloration were seen in the terminal ileum. <b>(C)</b> Images of H&E staining using light microscopy. The histological changes in the terminal ilea (representative images) in the control, NEC and BIF groups. Magnification: ×20. <b>(D)</b> Intestinal histological score. *<i>P</i> < 0.01 vs the control group, ^#<i>P</i> < 0.01 vs the NEC group, n = 6 animals per group.</p

Bifidobacterium prevented the disruption of TJ in vitro.

<p><b>(A)</b> Electron micrographs reveal the changes of intact TJ in vehicle group, LPS group and LPS+BIF group. <b>(B)</b> Immunofluorescence staining of TJ proteins localization in Caco-2 cells with or without LPS and BIF. Magnification: ×40. <b>(C)</b> Western blot for TJ proteins. Caco-2 cells were grown and treated with LPS and BIF and lysed. The lysates were used for immunoblotting for claudin-3, occludin, ZO-1 and β-actin. Representative results of one experiment are shown. Similar results were obtained in three independent experiments: vehicle group, LPS group, LPS+BIF group. <b>(D)</b> The intensity of the bands was quantified by scanning densitometry, standardized with respect to β-actin protein and expressed as mean ± SD fold change compared with vehicle cells. *<i>P</i> < 0.01 vs the vehicle group, ^#<i>P</i> < 0.01 vs the LPS group.</p

Bifidobacterium decreased zonulin protein release in vitro and in a rat NEC model.

<p><b>(A)</b> The release of zonulin was determined by ELISA in the Caco-2 cells. Data are mean ± SD from six independent experiments. *<i>P</i> < 0.01 vs the vehicle group, **<i>P</i> < 0.05 vs the LPS group. <b>(B)</b> Correlation analysis between fluorescein permeability and the release of zonulin in the Caco-2 cells. <b>(C)</b> The level of serum zonulin of animals was determined by ELISA. *<i>P</i> < 0.01 vs the control group, **<i>P</i> < 0.05 vs the NEC group, n = 6 animals per group. <b>(D)</b> Correlations analysis between intestinal permeability markers (plasma DX-4000–FITC) and serum zonulin concentrations.</p

Bifidobacterium prevented the disruption of TJ in a rat NEC model.

<p><b>(A)</b> TJ proteins localization was evaluated by Immunohistochemical staining in the terminal ileum of neonatal rats. Representative slides for control, NEC, and BIF were shown. Magnification: ×40, n = 3 to 6 per group. <b>(B)</b> Western blot for TJ proteins. Terminal ilea were subjected to immunoblotting for ZO-1, occludin claudin-3 and β-actin. Representative results of one experiment are shown. Similar results were obtained in three independent experiments: control group, NEC group, BIF group. <b>(C)</b> The intensity of the bands was quantified by scanning densitometry, standardized with respect to β-actin protein and expressed as mean ± SD fold change compared with control animals.*<i>P</i> < 0.01, ^##<i>P</i> < 0.05 vs the control group, ^#<i>P</i> < 0.01, **<i>P</i> < 0.05 vs the NEC group.</p

Experimental Investigation on Transition Characteristics of Different Rotary Disk Configurations

An experimental study was performed to investigate the liquid granulation process on the rotary disks. Four groups of rotary disks were specially designed, and rosin/paraffin mixture was used as the working fluid. At first, the nondimensional transition equations between different breakup modes were obtained. Then, comparative analyses were performed to characterize the critical transition characteristics. Higher <i>Q</i>⁺ values for bulged-block disk from direct drop to ligament and ligament to fully ligament were observed, while the first appearance of the sheet mode nearly coincided for all types of disks. Finally the transition maps were proposed, and the effects of operational conditions and liquid properties on transition characteristics were analyzed. The transition maps showed that the broadest transition area from ligament to sheet mode was indentified in arc-edge disk, while the narrowest area appeared in bulged-block disk. Moreover, the transition between different modes was promoted by decreasing <i>Q</i> and ω or increasing μ

Nanocrystals: Why Do Silver and Gold N‑Heterocyclic Carbene Precursors Behave Differently?

Synthesizing stable Au and Ag nanocrystals of narrow size distribution from metal–N-heterocyclic carbene (NHC) complexes remains a challenge, particularly in the case of Ag and when NHC ligands with no surfactant-like properties are used. The formation of nanocrystals by one-phase reduction of metal–NHCs (metal = Au, Ag) bearing common NHC ligands, namely 1,3-diethylbenzimidazol-2-ylidene (<b>L</b>^<b>1</b>), 1,3-bis­(mesityl)­imidazol-2-ylidene (<b>L</b>^<b>2</b>), and 1,3-bis­(2,6-^<i>i</i>Pr₂C₆H₃)­imidazol-2-ylidene (<b>L</b>^<b>3</b>), is presented herein. We show that both Au and Ag nanocrystals displaying narrow size distribution can be formed by reduction with amine–boranes. The efficiency of the process and the average size and size distribution of the nanocrystals markedly depend on the nature of the metal and NHC ligand, on the sequence in the reactant addition (i.e., presence or absence of thiol during the reduction step), and on the presence or absence of oxygen. Dodecanethiol was introduced to produce stable nanocrystals associated with narrow size distributions. A specific reaction is observed with Ag–NHCs in the presence of thiols whereas Au–NHCs remain unchanged. Therefore, different organometallic species are involved in the reduction step to produce the seeds. This can be correlated to the lack of effect of NHCs on Ag nanocrystal size. In contrast, alteration of Au nanocrystal average size can be achieved with a NHC ligand of great steric bulk (<b>L</b>^<b>3</b>). This demonstrates that a well-defined route for a given metal cannot be extended to another metal

The FL118 downstream target survivin play a role in FL118-mediated inhibition of cancer cell growth and apoptosis.

<p><b>a</b> Subconfluent HCT-8 colon cancer cells were infected with a lentiviral delivery system containing mock shRNA (shRNA-EGFP) or survivin shRNA. After puromycin selection at 2 µg/ml, the puromycin-selected infectants were treated with or without FL118 for 72 hours. Cells were then analyzed using the MTT assay for cell viability. Each bar is the mean ± SD derived from three independent assays. Of note, downregulation of survivin by the lentiviral survivin shRNA was confirmed by western blots (Fig. 5d). <b>b–d.</b> Subconfluent HCT-8 colon cancer cells were infected with lentiviral survivin shRNA particles or control lentiviral particles as above. After up to 7 days selection with puromycin (2 µg/ml), the mixed infectants were treated with or without FL118 (10 nM) for 36 hours. Cells were stained with Annexin V/PI, followed by flow cytometry. <b>b.</b> A representative flow cytometry result gated with PI (Y axis) and Annexin V (Alexa Fluor 647, X axis). <b>c</b> and <b>d.</b> Quantitative data from <b>b</b> for R4 (c) and R2+R4 (d) from three independent measures in parallel. Of note, R1 is Annexin V negative/PI positive cells; R2 is both Annexin V and PI positive cells (later apoptotic cells); R3 is both Annexin V and PI negative cells; and R4 is Annexin V positive/PI negative cells (early apoptotic cells).</p