Search results for "ALK"
showing 10 items of 4314 documents
Titanium Complexes Stabilized by a Sulfur‐Bridged Chelating Bis(aryloxo) Ligand as Active Catalysts for Olefin Polymerization
2004
The mixed-ligand complexes [Ti2(μ-OR)2(OR)2(κ3-tbop)2] (1a) for R = Me and (1b) R = Et were prepared by the reaction of Ti(OR)4 and H2tbop {H2tbop = 2,2′-thiobis[4-(1,1,3,3-tetramethylbutyl)phenol]} in methanol. Treatment of 1a and 1b with AlMe3 led to the substitution of terminal alkoxy groups to create the organometallic compounds [Ti2(μ-OR)2(κ3-tbop)2(Me)2] (2a) for R = Me and (2b) for R = Et. Controlled hydrolysis of 2b causes the evolution of methane and the formation of the titanoxane compounds [{Ti2(μ-OEt)2(κ3-tbop)2}2(μ-O)2]·2CH2Cl2 (3). Structures of 1a, 1b, 2a, 2b, and 3 were confirmed by NMR spectroscopy; 1b and 3 were further investigated with X-ray crystallography. Compounds 1a…
Ligands hybrides : synthèse et chimie de coordination
2011
This manuscript deals with the synthesis of hybrids ligands and their coordination ability. The first part is dedicated to Cp-imidazole, Cp-imidazolium and Cp-phosphine ligands. Several synthetic routes have been developed to reach these mixed ligands and their coordination chemistry has been studied with titanium. In a second part, a method developed in our laboratory to synthesize phosphine-olefines was applied to obtain a phosphino-diene bearing three potential coordination sites. We have studied the coordination modes of this hybrid ligand using various transition metals and some of the formed complexes were tested in catalysis. In the third part is described the coordination chemistry …
Psychosocial and environmental correlates of active commuting for university students.
2009
Abstract Objective To examine psychosocial and environmental correlates of active commuting to university (ACU) and explore its association with overall physical activity among college students. Methods The sample included 518 students (mean 22.4 years; 59.7% female) from two universities in Valencia, Spain. Weekly estimations of energy expenditure from ACU and total physical activity were obtained. Socio-economic status, self-efficacy, barriers to active transport, access to car and motorbike, access to public transport, walking and cycling facilities and distance to university were assessed. Data were collected April and May of 2009, using a self-administered survey. A structural equation…
Walking tourism in urban destinations: some preliminary results from a survey in Malaga with gps-based technologies
2018
Walking tourism in urban destinations can be defined as a sequence of day visits and/or a sequence of walking tours. In this work, GPS tracking data on spatio-temporal behaviour of walking tourists in Malaga are reported as case study. Malaga is a booming tourist destination characterized by a city centre, particularly suitable for a pedestrian visit. From 22nd January to 19th March 2018 for a total period of 41 days, a survey was carried out with a specific protocol: 103 interviews were conducted and 101 GPS valid tracks were collected. Walking tourists were systematically sampled, starting from the population of all tourists staying in the surveying day at some selected hotels in the city…
Urokinase activates macrophage PON2 gene transcription via the PI3K/ROS/MEK/SREBP-2 signalling cascade mediated by the PDGFR-β
2009
Aims We have recently shown that urokinase plasminogen activator (uPA) increases oxidative stress (OS), cholesterol biosynthesis, and paraoxonase 2 (PON2) expression in macrophages via binding to its receptor, the uPAR. Since PON2 is regulated by both OS and cholesterol content, we hypothesized that uPA elicits a cascade of signal transduction events shared by NADPH oxidase and cholesterol biosynthesis that culminates in PON2 gene expression. Here, we investigated the signalling pathway that leads to the expression of PON2 in macrophages in response to uPA. Methods and results The increase in macrophage PON2 mRNA levels in response to uPA was shown to depend on PON2 gene promoter activation…
Developmental dynamics of PAFAH1B subunits during mouse brain development.
2012
Platelet-activating factor (PAF) mediates an array of biological processes in the mammalian central nervous system as a bioactive lipid messenger in synaptic function and dysfunction (plasticity, memory, and neurodegeneration). The intracellular enzyme that deacetylates the PAF (PAFAH1B) is composed of a tetramer of two catalytic subunits, ALPHA1 (PAFAH1B3) and ALPHA2 (PAFAH1B2), and a regulatory dimer of LIS1 (PAFAH1B1). We have investigated the mouse PAFAH1B subunit genes during brain development in normal mice and in mice with a hypomorphic allele for Lis1 (Lis1/sLis1; Cahana et al. [2001] Proc Natl Acad Sci U S A 98:6429–6434). We have analyzed quantitatively (by means of real-time poly…
Early life stress programming of NG2+ glia transcriptome alters functional properties of voltage gated sodium (Nav) channels and cognitive performance
2020
AbstractThe precise mechanisms underlying the detrimental effects of early life stress (ELS) on adult mental health remain still elusive. To date, most studies have exclusively targeted neuronal populations and not considered neuron-glia crosstalk as a crucially important element for the integrity of stress-related brain function. Here, we have investigated the impact of ELS on a glial subpopulation with unique properties in brain homeostasis, the NG2+ cells. ELS shifted the NG2+ transcriptome towards more mature stages, and these transcriptional effects were dependent on stress-induced glucocorticoids. The functional relevance of one candidate gene, Scn7a, could be confirmed by an increase…
Placental alkaline phosphatase types in Germany
1974
The phenotypes of placental alkaline phosphatase were determined in a sample of 231 Germans and 109 non-Germans. The observed gene frequencies of the German sample were \({\text{Pl}}^{{\text{S}}_{\text{1}} } {\text{ = 0}}{\text{.654}}\), \({\text{Pl}}^{{\text{F}}_{\text{1}} } {\text{ = 0}}{\text{.247}}\), and \({\text{Pl}}^{{\text{I}}_{\text{1}} } {\text{ = 0}}{\text{.097}}\). No association could be found with placental weight. Lower birth weight was correlated with an increase of the \({\text{Pl}}^{{\text{I}}_{\text{1}} } \) gene frequency.
Enabling Backoff and Eliminating Redundant Idle Period for Medium Access in LTE-U
2017
To address the burgeoning demand for mobile data, 3GPP is actively studying the capability of operating LTE in the unlicensed band, referred to as LTE-U. One of the main challenges of this approach is to maintain better coexistence between WiFi and LTE-U devices. To enable the coexistence, the listen before talk (LBT) principle has been adopted for LTE-U medium access with two flavors of mechanisms, i.e., load based equipment (LBE) and frame based equipment (FBE) access. In this paper, we consider the FBE mechanism and enhance its performance by introducing a backoff procedure for LTE devices. We investigate the original FBE mechanism defined by 3GPP and the enhanced FBE (E- FBE) mechanism fr…
Transtauksābju izplatība Latvijas produktos
2018
Transtaukskābju izplatība Latvijas produktos. Kulesha A., zinātniskais vadītājs Dr.chem.Vadims Bartkevičs, Kursa darbs, 72 lappuses, 53 attēli, 100 literatūras avoti. Latviešu valodā. Transtaukskābes veidojas daļējas hidrogenēšanas procesā, kurā šķidrās augu eļļas pārvēršas margarīnā un augu kulinārajos taukos. Zinātniekiem visā pasaulē rodas bažas, ka šis process var izraisīt nelabvēlīgas sekas, jo dabīgas neaizstājamās taukskābes pārveidojas, bet jaunie mākslīgie izomēri struktūras ziņā līdzinās piesātinātiem taukiem bez būtiskas sākotnējo savienojumu metaboliskās aktivitātes. Šī darba mērķis ir izpētīt taukskābju saturu saldos mīklas izstrādājumos, īpašu uzmanību pievēršos transtaukskābē…