Final Progress Report

In this project we have established guidelines for the design on organic chromophores suitable for producing high triplet yields via singlet fission. We have proven their utility by identifying a chromophore of a structural class that had never been examined for singlet fission before, 1,3-diphenylisobenzofuran, and demonstrating in two independent ways that a thin layer of this material produces a triplet yield of 200% within experimental error. We have also designed a second chromophore of a very different type, again of a structural class that had not been examined for singlet fission before, and found that in a thin layer it produces a 70% triplet yield. Finally, we have enhanced the theoretical understanding of the quantum mechanical nature of the singlet fission process

Optimal control of Allen-Cahn systems

Optimization problems governed by Allen-Cahn systems including elastic effects are formulated and first-order necessary optimality conditions are presented. Smooth as well as obstacle potentials are considered, where the latter leads to an MPEC. Numerically, for smooth potential the problem is solved efficiently by the Trust-Region-Newton-Steihaug-cg method. In case of an obstacle potential first numerical results are presented

2-Deoxyglucose selectively inhibits Fc and complement receptor-mediated phagocytosis in mouse peritoneal macrophages II...

Macrophages incubated in 2-deoxy-D-glucose (2-dG)-containing medium showed a marked decrease in cellular ATP content, and were unable to ingest IgG- and complement-coated erythrocytes via the corresponding membrane receptors for these ligands. However, the inhibitory effects of 2-dG on Fc- and C3 receptor-mediated phagocytosis were not a consequence of lowered macrophage ATP levels since addition of glucose or mannose to the culture medium restored the capacity of the macrophages to ingest IgG- and C3-coated particles without increasing ATP levels. These results indicate that Fc- and C3 receptor-mediated phagocytosis (opsonin dependent) differs qualitatively from the ingestion of latex and zymosan particles (opsonin independent); they suggest that the same regulatory molecules govern the responses of phagocytic cells to signals initiated by both the Fc and C3 receptors. The possibility that these molecules are regulated by glycosylation is discussed

2-Deoxyglucose selectively inhibits Fc and complement receptor-mediated phagocytosis in mouse peritoneal macrophages. I. Description of the inhibitory effect

Incubation of normal or thioglycollate-elicited mouse peritoneal macrophages with 2-deoxy-D-glucose (2-dG) inhibits the capacity of these macrophages to phagocytize IgG- or complement-coated particles via their Fc and C3 receptors. 2-dG has no inhibitory effect on the capacity of these macrophages to phagocytize latex or zymosan particles, which are ingested in the absence of specific opsonins, and it does not inhibit binding of IgG- or C3-coated particles to their respective receptors on the macrophage's plasma membrane. 2-dG exerts its inhibitory effect on the macrophage and not on the opsonized particle. The inhibition is independent of particle size, occurs within 15-30 min of addition of this glucose analogue to the medium at 37 degrees C, cannot be overcome by supra-agglutinating amounts of opsonizing antibody, and is completely reversible by substitution of 5.5 mM glucose for 50 mM 2-dG in the medium. Addition of equimolar amounts of glucose or mannose, but not of fructose, galactose, fucose, or glucosamine, to medium containing 50 mM 2-dG results in substantial reversal of the inhibitory effect of 2-dG on Fc and C3 receptor mediated phagocytosis

Secondary Ion Mass Spectrometry:a Tool for Identification of Matrix-isolated Species

An argon matrix-isolated propane sample (1:150, 10 K) is used to demonstrate the applicability of secondary ion mass spectral analysis to the characterization of matrix-isolated species

Modulation of Fc receptors of mononuclear phagocytes by immobilized antigen-antibody complexes. Quantitative analysis of the relationship between ligand number and Fc receptor response

Macrophages plated on surfaces coated with antigen-IgG complexes lose the capacity to bind and ingest IgG-coated particles via their Fc receptors (FcR). Macrophages plated on surfaces containing a similar number of IgG molecules that are not complexed to antigen show little or no decrease in FcR activity. Using a rat monoclonal antibody (2.4G2 IgG) directed against the trypsin-resistant FcR (FcRII) of mouse macrophages we show that the decrease in receptor activity induced by substrate-adherent immune complexes is caused by the physical removal of 60 and 75% of FcRII from the nonadherent membrane surfaces of resident and thioglycollate broth-induced macrophages, respectively. Macrophages maintained on antigen-IgG-coated surfaces for up to 44 h show no recovery in FcRII activity or number, while macrophages on control surfaces exhibit two and threefold increases, respectively, in these parameters. Macrophages maintained for 72 h on antigen-IgG-coated surfaces show a small recovery in FcRII activity, and in the number of FcRII that is accessible to bind 125I-2.4G2 IgG. FcRII modulation, as measured by the binding of 125I-labeled 2.4G2 IgG, is initiated when the number of IgG molecules bound to the substrate is approximately equal to the total number of FcRII on the plasma membranes of all the macrophages on the substrate. FcRII activity and number decrease linearly as the number of substrate-bound IgG molecules increases exponentially, and are maximally reduced when the number of IgG molecules on the substrate is 20-fold greater than the total number of all FcRII on the surfaces of all the macrophages in the culture. Thus there is a stoichiometric relationship between the number of IgG molecules on the substrate and the extent of FcRII modulation

Effects of immobilized immune complexes on Fc- and complement-receptor function in resident and thioglycollate-elicited mouse peritoneal macrophages

We have examined the Fc- and complement-receptor function of resident and thioglycollate-elicited mouse peritoneal macrophages plated on surfaces coated with rabbit antibody-antigen complexes and with complement. We derive four major conclusions from these studies. (a) The trypsin-resistant Fc receptors of resident and thioglycollate-elicited macrophages are completely modulated when these cells are plated on rabbit antibody-antigen complexes. Residual Fc receptor activity is a result of the incomplete modulation of trypsin-sensitive IgG2a receptors. (b) The complement receptors of thioglycollate-elicited macrophages, but not of resident macrophages, are modulated when these cells are plated on complement-coated surfaces. The capacity of the two cell types to modulate their complement receptors is correlated with their ability to ingest complement-coated erythrocytes. (c) The complement and Fc receptors of both types of macrophages move independently of one another. (d) Complement masks the Fc segments of IgG in immune complexes thereby rendering them ineffective as ligands for macrophage Fc receptors

Insertion of Carbenes into Deprotonated nido-Undecaborane, B11H13(2-)

We have examined the insertion of carbenes carrying leaving groups into the [nido-B11H13]2&minus; dianion to form the [closo-1-CB11H12]&minus; anion. The best procedure uses CF3SiMe3 and LiCl as the source of CF2. It is simple, convenient and scalable and proceeds with 70&ndash;90% yield. Density functional calculations have been used to develop a mechanistic proposal that accounts for the different behavior of CF2, requiring only one equivalent of base for successful conversion of Na[nido-B11H14]&minus; to [closo-1-CB11H12]&minus;, and CCl2 and CBr2, which require more</div

Effects of immobilized immune complexes on Fc- and complement-receptor function in resident and thioglycollate-elicited mouse peritoneal macrophages

We have examined the Fc- and complement-receptor function of resident and thioglycollate-elicited mouse peritoneal macrophages plated on surfaces coated with rabbit antibody-antigen complexes and with complement. We derive four major conclusions from these studies. (a) The trypsin-resistant Fc receptors of resident and thioglycollate-elicited macrophages are completely modulated when these cells are plated on rabbit antibody-antigen complexes. Residual Fc receptor activity is a result of the incomplete modulation of trypsin-sensitive IgG2a receptors. (b) The complement receptors of thioglycollate-elicited macrophages, but not of resident macrophages, are modulated when these cells are plated on complement-coated surfaces. The capacity of the two cell types to modulate their complement receptors is correlated with their ability to ingest complement-coated erythrocytes. (c) The complement and Fc receptors of both types of macrophages move independently of one another. (d) Complement masks the Fc segments of IgG in immune complexes thereby rendering them ineffective as ligands for macrophage Fc receptors

Optimal control of Allen-Cahn systems

Optimization problems governed by Allen-Cahn systems including elastic effects are formulated and first-order necessary optimality conditions are presented. Smooth as well as obstacle potentials are considered, where the latter leads to an MPEC. Numerically, for smooth potential the problem is solved efficiently by the Trust-Region-Newton-Steihaug-cg method. In case of an obstacle potential first numerical results are presented