Transformation of Formazanate at Nickel(II) Centers to Give a Singly Reduced Nickel Complex with Azoiminate Radical Ligands and Its Reactivity toward Dioxygen.

The heteroleptic (formazanato)nickel bromide complex LNi(μ-Br)NiL [LH = Mes-NH-N═C(-tol)-N═N-Mes] has been prepared by deprotonation of LH with NaH followed by reaction with NiBr(dme). Treatment of this complex with KC led to transformation of the formazanate into azoiminate ligands via N-N bond cleavage and the simultaneous release of aniline. At the same time, the potentially resulting intermediate complex L'Ni [L' = HN═C(-tol)-N═N-Mes] was reduced by one additional electron, which is delocalized across the π system and the metal center.

Electron transfer within β-diketiminato nickel bromide and cobaltocene redox couples activating CO.

Reduction of β-diketiminato nickel(ii) complexes (LtBuNiII) to the corresponding nickel(i) compounds does not require alkali metal compounds but can also be performed with the milder cobaltocenes. LtBuNiBr and Cp2Co have rather similar redox potentials, so that the equilibrium with the corresponding electron transfer compound [LtBuNiIBr][Cp2CoIII] (ETC) clearly lies on the side of the starting materials. Still, the ETC portion can be used to activate CO2 yielding a mononuclear nickel(ii) carbonate complex and ETC can be isolated almost quantitatively from the solutions through crystallisation.

Selective Transformation of Nickel-Bound Formate to CO or C-C Coupling Products Triggered by Deprotonation and Steered by Alkali-Metal Ions.

The complexes [L Ni(OCO-κ O,C)]M [N(SiMe ) ] (M=Li, Na, K), synthesized by deprotonation of a nickel formate complex [L NiOOCH] with the corresponding amides M[N(SiMe ) ], feature a Ni -CO core surrounded by Lewis-acidic cations (M ) and the influence of the latter on the behavior and reactivity was studied. The results point to a decrease of CO activation within the series Li, Na, and K, which is also reflected in the reactivity with Me SiOTf leading to the liberation of CO and formation of a Ni-OSiMe complex. Furthermore, in case of K , the {[K [N(SiMe ) ] } shell around the Ni-CO entity was shown to have a large impact on its stabilization and behavior.

The Effect of Bulk Depth and Irradiation Time on the Surface Hardness and Degree of Cure of Bulk-Fill Composites.

Statement Of Problem: For many years, application of the composite restoration with a thickness less than 2 mm for achieving the minimum polymerization contraction and stress has been accepted as a principle. But through the recent development in dental material a group of resin based composites (RBCs) called Bulk Fill is introduced whose producers claim the possibility of achieving a good restoration in bulks with depths of 4 or even 5 mm.

Objectives: To evaluate the effect of irradiation times and bulk depths on the degree of cure (DC) of a bulk fill composite and compare it with the universal type.

Patterned deposition of metal-organic frameworks onto plastic, paper, and textile substrates by inkjet printing of a precursor solution.

Flexible in many aspects: inkjet printing of metal-organic frameworks permits their larger area, high-resolution deposition in any desired pattern, even in the form of gradients or shades. When flexible substrates are used, many applications can be envisioned, such as sensing and capture of hazardous gases for personal safety measures.

Phosphoinositide metabolism and prostacyclin formation in retinal microvascular endothelium: stimulation by adenine nucleotides.

Phosphoinositide lipid metabolism and prostacyclin production are implicated in endothelium dependent vascular relaxation in large blood vessels. To determine if these biochemical pathways might be involved in the regulation of microvascular tone in the retina, we measured the formation of 6-keto-prostaglandin-F1 alpha, the stable end product of prostacyclin, and inositol phosphates from 3H-labeled phosphoinositide lipids, in endothelial cells prepared from bovine retinal microvessels and maintained in long-term culture. We found that adenosine 5'-triphosphate and adenosine 5'-diphosphate both stimulated a dose-dependent accumulation of inositol phosphates and of 6-keto-prostaglandin-F1 alpha in these cells.

Lead activates calmodulin sensitive processes.

The effect of lead on two calcium sensitive processes was determined. Micromolar concentrations of lead successfully replaced calcium in the activation of calmodulin-sensitive phosphodiesterase and in the promotion of potassium loss from erythrocytes. Both actions of lead were blocked by trifluoperazine--an inhibitor of calmodulin function.

Primary culture of capillary endothelium from rat brain.

To provide an in vitro system for studies of brain capillary function we developed a method for culture of brain capillary endothelial cells. Capillaries were isolated from rat brain and enzymatically treated to remove the basement membrane and contaminating pericytes. Subsequent Percoll gradient centrifugation resulted in a homogeneous population of capillary endothelial cells that attached to a collagen substrate and incorporated [3H]thymidine.

Complement-mediated cytotoxic effects on pancreatic islets with sera from diabetic patients.

Sera from 11/30 patients with juvenile-onset-type diabetes (JOD) had cytotoxic effects on isolated pancreatic islets from hamsters when guinea pig complement was present. The cytotoxic activity could be readily eliminated by heating the guinea pig complement at 56 degrees C for 30 min, thus demonstrating a complement-dependent process. Complement-dependent cytotoxicity toward pancreatic islets was not observed with sera from 11 patients with maturity-onset-type diabetes, 4 nondiabetic hospital patient controls, and 28 healthy adult subjects.

The spontaneous release of a high-molecular-weight aggregate containing immunoglobulin G from the surface of Ehrlich ascites tumor cells.

The spontaneous release of tumor cell antigens from the cell surface into the circulation has been proposed as a mechanism whereby tumors may escape the immune response of the host. In this study we have found that Ehrlich ascites tumor cells after removal from the host (mouse) spontaneously release significant amounts of cell surface components during incubation for 1 h in cold isotonic buffer. Immunodiffusion studies revealed that immunoglobulin G (IgG) and a complement component (C3) are included in this spontaneously released material.