Search results for "NAD"
showing 10 items of 2033 documents
Melastomeae come full circle: biogeographic reconstruction and molecular clock dating.
2001
Rhexia, with 11 species in the Coastal Plain province of North America, is the only temperate zone endemic of the tropical eudicot family Melastomataceae. It is a member of the only pantropical tribe of that family, Melastomeae. Based on the chloroplast gene ndhF, we use a fossil-calibrated molecular clock to address the question of the geographic origin and age of Rhexia. Sequences from 37 species in 21 genera representing the tribe's geographical range were analyzed together with five outgroups. To obtain better clade support, another chloroplast region, the rpl16 intron, was added for 24 of the species. Parsimony analysis of the combined data and maximum-likelihood analysis of ndhF alone…
Synthesis and olefin homo- and copolymerization behavior of new vanadium complexes bearing [OSSO]-type ligands
2017
Novel vanadium complexes bearing [OSSO]-type ligands having two phenolato units linked through the –CH2S(CH2)4SCH2– (1V) or –CH2S(CH2)2SCH2– (2V) bridge are synthesized with good yields by reacting a deprotonated ligand with VCl4. They are then used in ethylene (co)polymerization after activation with EtAlCl2 and Et2AlCl. In the presence of EtAlCl2, both complexes promote ethylene polymerization with very high activities, over 4 × 107 g/(mol h), leading to PEs with high molecular weight and narrow molecular weight distribution. The prepared complexes exhibit lower activity for ethylene/1-octene copolymerization. It is also revealed that the catalyst based on the –CH2S(CH2)4SCH2– bridged com…
Vanadium catalysts for ethylene-norbornene copolymerization
2020
Cyclic olefin copolymers (COCs) are a promising group of materials with specific, projectable properties. In this group, copolymers of ethylene and norbornene are of particular interest. A variety of transition metal complexes are used for their synthesis, mostly elements from group 4. This review presents the application of vanadium catalysts with various types of ligands in the synthesis of ethylene-norbornene copolymers. The influence of ligands and reaction conditions on the activity of catalyst and selected properties of copolymers are described in this paper.
Evolution of the optimal catalytic systems for the oxidative dehydrogenation of ethane: The role of adsorption in the catalytic performance
2022
Three samples that correspond to the evolution of optimal catalytic systems for the oxidative dehydrogenation of ethane have been synthesized and compared in terms of catalytic behavior and adsorption properties: (i) vanadium oxide supported on alumina, (ii) Sn-promoted NiO, and (iii) multicomponent MoVTeNbO with the M1 structure. The main difference in catalytic performance lies in the extent of the overoxidation of the ethylene formed, following the order VOx/Al2O3 > NiSnOx > MoVTeNb-M1. Accordingly, the selectivity to ethylene at medium and high ethane conversion follows the order MoVTeNb-M1 > NiSnOx > VOx/Al2O3. These results are confirmed by the relative reaction rates observed for the…
Direct oxidation of isobutane to methacrolein over V-MCM-41 catalysts
2004
High vanadium content mesoporous vanado-silicates with MCM-41-like structure, obtained by the atrane route, catalyse the direct oxidation of isobutane to methacrolein with 30% selectivity, and a total dehydrogenation (olefin plus methacrolein) selectivity up to 74%.
Ethylene/1-olefin copolymerization behaviour of vanadium and titanium complexes bearing salen-type ligand
2013
Ethylene/1-olefin copolymerization using vanadium and titanium complexes bearing tetradentate [O,N,N,O]-type ligand and EtAlCl2 or MAO as a cocatalyst is carried out. In the presence of the vanadium complex activated with EtAlCl2 is observed (a) negative “comonomer effect”, (b) high comonomer incorporation and narrow chemical composition distribution (CCD), (c) unexpected copolymer microstructure, and (d) increased molecular weight of copolymers when compared with the homopolymer. In contrast, titanium catalyst gives copolymers with lower 1-olefin content and broad CCD. Supported complexes show higher activity, lower 1-olefins incorporation and give copolymers with ultra high molecular weig…
NADPH-diaphorase activity of nitric oxide synthase in the olfactory bulb: co-factor specificity and characterization regarding the interrelation to N…
1994
The neuronal form of the enzyme nitric oxide synthase (nNOS) synthesizes the messenger molecule nitric oxide (NO). In addition to NO formation, nNOS exhibits a so-called NADPH-diaphorase (NADPH-d) activity. This study focused on the characterization of NADPH-d activity with regard to NO formation in the rat olfactory bulb. In this area of the brain pronounced staining is localized in discrete populations of neuronal somata and in olfactory glomeruli. Diaphorase staining combined with demonstration of nNOS by polyclonal antibodies revealed that NADPH-d activity of neuron somata is associated with nNOS immunoreactivity. It is concluded that neuron somata exhibit NADPH-d activity of nNOS. NAD…
A prospective randomised, open-labeled, trial comparing sirolimus-containing versus mTOR-inhibitor-free immunosuppression in patients undergoing live…
2010
Abstract Background The potential anti-cancer effects of mammalian target of rapamycin (mTOR) inhibitors are being intensively studied. To date, however, few randomised clinical trials (RCT) have been performed to demonstrate anti-neoplastic effects in the pure oncology setting, and at present, no oncology endpoint-directed RCT has been reported in the high-malignancy risk population of immunosuppressed transplant recipients. Interestingly, since mTOR inhibitors have both immunosuppressive and anti-cancer effects, they have the potential to simultaneously protect against immunologic graft loss and tumour development. Therefore, we designed a prospective RCT to determine if the mTOR inhibito…
Role of MTHFR (677, 1298) haplotype in the risk of developing secondary leukemia after treatment of breast cancer and hematological malignancies
2007
Therapy-related myelodysplasia and acute myeloid leukemia (t-MDS/AML) is a malignancy occurring after exposure to chemotherapy and/or radiotherapy. Polymorphisms involved in chemotherapy/radiotherapy response genes could be related to an increased risk of developing this neoplasia. We have studied 11 polymorphisms in genes of drug detoxification pathways (NQO1, glutathione S-transferase pi) and DNA repair xeroderma pigmentosum, complementation group (3) (XPC(3), X-ray repair cross complementing protein (1)), Nijmegen breakage syndrome (1), excision repair cross-complementing rodent repair deficiency, complementation group (5) and X-ray repair cross complementing protein (3) and in the methy…
Inflammation and prostate cancer
2008
Prostate cancer remains a major health concern for the male population throughout the Western world. It is today widely accepted that inflammation has a role in many human cancers. In fact, inflammation is thought to incite carcinogenesis by causing cell and genome damage, promoting cellular turnover and creating a tissue microenvironment that can enhance cell replication, angiogenesis and tissue repair. Accordingly, there is a body of literature suggesting a link between chronic inflammation and prostate cancer, in which prostate inflammation may contribute to the promotion of prostate cancer development. On the other hand, high levels of endogenous gonadal steroids are considered as risk…