Impaired responses of leukemic dendritic cells derived from a human myeloid cell line to LPS stimulation

Several myeloid leukemia-derived cells have been reported to possess the ability to differentiate into dendritic cells (DC). MUTZ-3, a myeloid leukemia cell line, responds to GM-CSF, IL-4 and TNF-alpha, and acquires a phenotype similar to immature monocyte-derived DC (MoDC). In the present study, MUTZ-3-derived DC (MuDC) showed high level expression of HLA class II molecules, CD80 and CD86, and were able to function as potent antigen presenting cells as previously reported. Interestingly, MuDC maturation was induced by CD40- mediated stimulation, but not by LPS stimulation. We analyzed CCR1, CCR7 and Toll-like receptor (TLR) expressions in MuDC, and measured IL-10 and IL-12 production after maturation stimuli. Although MuDC expressed the mRNA for TLR4, a major component of the LPS receptor system, they did not show an enhanced level of CCR7 or cytokine production after LPS stimulation. In contrast, they responded to CD40 stimulation, which resulted in increased levels of CD83, CD86 and CCR7. Moreover, while LPS- stimulated MoDC could potently stimulate NK cells in a DC-NK cell co-culture, LPS-stimulated MuDC failed to stimulate primary NK cells. Taken together, our findings suggest that, although MuDC express TLR4, unlike TNF-alpha and IL-1beta, LPS does not stimulate MuDC to acquire mature phenotypes, and they may have impaired activity to initiate innate immune response.     

A Riemannian geometric framework for manifold learning of non-Euclidean data

Advances in Data Analysis and Classification - A growing number of problems in data analysis and classification involve data that are non-Euclidean. For such problems, a naive application of vector...     

Scaling behavior of mixed-state hall effect in MgB2 thin films

The Hall resistivity (ρ_xy) and the longitudinal resistivity (ρ_xx) in c-axis-oriented superconducting MgB₂ thin films have been investigated in extended fields up to 18 T. We have observed a scaling behavior between the Hall resistivity and the longitudinal resistivity, , where the exponent (β) is observed to be independent of the temperatures and the magnetic fields. For a wide magnetic field region from 1 to 18 T and a wide temperature region from 10 to 28 K, a universal power law with β = 2.0 ± 0.1 was observed in c-axis-oriented MgB₂ thin films. These results can be well interpreted by using recent models.     

Benzotrithiophene-based Covalent Organic Framework Photocatalysts with Controlled Conjugation of Building Blocks for Charge Stabilization

Covalent organic frameworks have recently shown high potential for photocatalytic hydrogen production. However, their structure-property-activity relationship has not been sufficiently explored to identify a research direction for structural design. Herein, we report the design and synthesis of four benzotrithiophene (BTT)-based covalent organic frameworks (COFs) with different conjugations of building units, and their photocatalytic activity for hydrogen production. All four BTT-COFs had slipped parallel stacking patterns with high crystallinity and specific surface areas. The change in the degree of conjugation was found to rationally tune the rate of photocatalytic hydrogen evolution. Based on the experimental and calculation results, the tunable photocatalytic performance could be mainly attributed to the electron affinity and charge trapping of the electron accepting units. This study provides important insights for designing covalent organic frameworks for efficient photocatalysts.     

Revealing Isolated M−N3C1 Active Sites for Efficient Collaborative Oxygen Reduction Catalysis

Single atom catalysts (SACs) are of great importance for oxygen reduction, a critical process in renewable energy technologies. The catalytic performance of SACs largely depends on the structure of their active sites, but explorations of highly active structures for SAC active sites are still limited. Herein, we demonstrate a combined experimental and theoretical study of oxygen reduction catalysis on SACs, which incorporate M−N₃C₁ site structure, composed of atomically dispersed transition metals (e.g., Fe, Co, and Cu) in nitrogenated carbon nanosheets. The resulting SACs with M−N₃C₁ sites exhibited prominent oxygen reduction catalytic activities in both acidic and alkaline media, following the trend Fe−N₃C₁ > Co−N₃C₁ > Cu−N₃C₁. Theoretical calculations suggest the C atoms in these structures behave as collaborative adsorption sites to M atoms, thanks to interactions between the d/p orbitals of the M/C atoms in the M−N₃C₁ sites, enabling dual site oxygen reduction.     

Multifunctional linear methacrylate copolymer polyenes having pendant vinyl groups: Synthesis and photoinduced thiol–ene crosslinking polyaddition

UV‐induced thiol‐ene crosslinked films composed of linear methacrylate copolymers having pendant enes (MCPenes) are reported. An approach involving a combination of controlled radical polymerization to synthesize well‐controlled pendant hydroxyl containing copolymers (MCP_OHs) with the following facile carbodiimide coupling of the formed MCP_OHs with enes allows for the synthesis of well‐controlled MCPenes with narrow molecular weight distribution. The density of the pendant enes in MCPenes are easily modulated by varying monomer ratios in the feed. Under UV irradiation, the resulting MCPenes undergo thiol‐ene polyaddition reactions with polythiols to form crosslinked films with a uniform network. The results from thermal and mechanical analysis suggest these properties are tuned by adjusting the densities of pendant enes in MCPenes and the amount of thiols in the reactive mixtures. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 572–581     

Polymerization and copolymerization of ethene initiated with disiloxane-bridged biscyclopentadienylzirconium complexes and methylaluminoxane

The disiloxane-bridged zirconocene complexes, tetramethyldisiloxanediylbis (cyclopentadienyl)zirconium dichloride and tetramethyldisiloxanediylbis(cyclopentadienyl) dimethylzirconium initiate the homopolymerization of ethene as well as the copolymerization of ethene and α-olefin with a modified methylaluminoxane as cocatalyst. The catalyst systems give resonable activity but the molecular weight of polyethene decreases drastically with increasing polymerization temperature.     

Polymerization of ethene initiated with a mixture of siloxane-bridged mono- and dinuclear zirconocenes

In the polymerization of ethene cocatalyzed with modified methylaluminoxane, the catalyst activities of the siloxane-bridged dinuclear zirconocenes, tetramethyldisiloxanediylbis(cyclopentadienylindenylzirconium dichloride) ( 3 ) and hexamethyltrisiloxanediylbis(cyclopentadienylindenylzirconium dichloride) ( 4 ) were lower than that obtained with the siloxane-bridged mononuclear zirconocene, tetramethyldisiloxanediyldicyclopentadienyldimethylzirconium ( 1 ). On the other hand, weight-average molecular weight M̄_w and ratio of weight- to number-average molecular weights M̄_w/M̄_n of polyethene (PE) obtained with 3 or 4 were higher than those of PE obtained with 1. For a binary mixture of 1/3 or 1/4 , it was found that the obtained PE exhibits a bimodal molecular weight distribution for an appropriate composition of the mixed zirconocenes. M̄_w/M̄_n of PE could be adjusted by changing the relative concentrations of the two zirconocenes.