Elastic metamaterials with simultaneously negative effective shear modulus and mass density

We propose a type of elastic metamaterial comprising fluid-solid composite inclusions which can possess negative shear modulus and negative mass density over a large frequency region. Such a solid metamaterial has a unique elastic property that only transverse waves can propagate with a negative dispersion while longitudinal waves are forbidden. This leads to many interesting phenomena such as negative refraction, which is demonstrated by using a wedge sample, and a significant amount of mode conversion from transverse waves to longitudinal waves that cannot occur on the interface of two natural solids

Controlling magnetization reversal in Co/Pt nanostructures with perpendicular anisotropy

We demonstrate a simple method to tailor the magnetization reversal mechanisms of Co/Pt multilayers by depositing them onto large area nanoporous anodized alumina (AAO) with various aspect ratios, A = pore depth/diameter. Magnetization reversal of composite (Co/Pt)/AAO films with large A is governed by strong domain-wall pinning which gradually transforms into a rotation-dominated reversal for samples with smaller A, as investigated by a first-order reversal curve method in conjunction with analysis of the angular dependent switching fields. The change of the magnetization reversal mode is attributed to topographical changes induced by the aspect ratio of the AAO templates.Comment: 12 pages, 3 figure

trans-Diaqua­bis[5-carb­oxy-4-carboxyl­ato-2-(4-pyridinio)-1H-imidazol-1-ido-κ2 N 3,O 4]iron(II)

In the title complex, [Fe(C10H6N3O4)2(H2O)2], the FeII atom is located on a twofold rotation axis and is coordinated by two trans-positioned N,O-bidentate and zwitterionic 5-carboxy-2-(pyridinium-4-yl)-1H-imidazol-1-ide-4-carboxylate H2PIDC− ligands and two water mol­ecules in a distorted environment. In the crystal packing, a three-dimensional network is constructed via hydrogen-bonding involving the water mol­ecules, uncoordinated imidazole N atom, protonated pyridine N and carboxyl­ate O atoms

α-Lactosylceramide Protects Against iNKT-Mediated Murine Airway Hyperreactivity and Liver Injury Through Competitive Inhibition of Cd1d Binding.

Invariant natural killer T (iNKT) cells, which are activated by T cell receptor (TCR)-dependent recognition of lipid-based antigens presented by the CD1d molecule, have been shown to participate in the pathogenesis of many diseases, including asthma and liver injury. Previous studies have shown the inhibition of iNKT cell activation using lipid antagonists can attenuate iNKT cell-induced disease pathogenesis. Hence, the development of iNKT cell-targeted glycolipids can facilitate the discovery of new therapeutics. In this study, we synthesized and evaluated α-lactosylceramide (α-LacCer), an α-galactosylceramide (α-GalCer) analog with lactose substitution for the galactose head and a shortened acyl chain in the ceramide tail, toward iNKT cell activation. We demonstrated that α-LacCer was a weak inducer for both mouse and human iNKT cell activation and cytokine production, and the iNKT induction by α-LacCer was CD1d-dependent. However, when co-administered with α-GalCer, α-LacCer inhibited α-GalCer-induced IL-4 and IFN-γ production from iNKT cells. Consequently, α-LacCer also ameliorated both α-GalCer and GSL-1-induced airway hyperreactivity and α-GalCer-induced neutrophilia when co-administered in vivo. Furthermore, we were able to inhibit the increases of ConA-induced AST, ALT and IFN-γ serum levels through α-LacCer pre-treatment, suggesting α-LacCer could protect against ConA-induced liver injury. Mechanistically, we discerned that α-LacCer suppressed α-GalCer-stimulated cytokine production through competing for CD1d binding. Since iNKT cells play a critical role in the development of AHR and liver injury, the inhibition of iNKT cell activation by α-LacCer present a possible new approach in treating iNKT cell-mediated diseases

trans-Diaqua­bis[5-carb­oxy-2-(3-pyrid­yl)-1H-imidazole-4-carboxyl­ato-κ2 N 3,O 4]iron(II)

In the title complex, [Fe(C10H6N3O4)2(H2O)2], the FeII atom is located on an inversion centre and is trans-coordinated by two N,O-bidentate 5-carb­oxy-2-(3-pyrid­yl)-1H-imidazole-4-carb­oxy­l­ate ligands and two water mol­ecules, defining a distorted octa­hedral environment. A two-dimensional network of N—H⋯O and O—H⋯O hydrogen bonds extending parallel to (110) helps to stabilize the crystal packing

trans-Diaqua­bis­[5-carb­oxy-4-carboxyl­ato-2-(4-pyridinio)-1H-imidazol-1-ido-κ2 N 3,O 4]zinc(II)

In the title complex, [Zn(C10H6N3O4)2(H2O)2], the ZnII atom is located on a twofold rotation axis and is coordinated by two trans-positioned N,O-bidentate and zwitterionic 5-carb­oxy-4-carboxyl­ato-2-(4-pyridinio)-1H-imidazol-1-ide (H2PIDC−) ligands and two water mol­ecules, defining a distorted octa­hedral environment. The complete solid-state structure can be described as a three-dimensional supra­molecular framework, stabilized by extensive hydrogen-bonding inter­actions involving the coordinated water mol­ecules, uncoordin­ated imidazole N atom, protonated pyridine N and carboxyl­ate O atoms of the H2PIDC− ligands