Search results for "amination"
showing 10 items of 1702 documents
Reduction-oxidation dynamics of oxidized graphene: Functional group composition dependent path to reduction
2018
Micrometer-sized oxidation patterns containing varying composition of functional groups including epoxy, ether, hydroxyl, carbonyl, carboxyl, were created in chemical vapor deposition grown graphene through scanning probe lithography and pulsed laser two-photon oxidation. The oxidized graphene films were then reduced by a focused x-ray beam. Through in-situ x-ray photoelectron spectroscopy measurement, we found that the path to complete reduction depends critically on the total oxygen coverage and concentration of epoxy and ether groups. Over the threshold concentrations, a complex reduction-oxidation process involving conversion of functional groups of lower binding energy to higher bindin…
Asymmetric Synthesis of Fluorinated Isoindolinones through Palladium-Catalyzed Carbonylative Amination of Enantioenriched Benzylic Carbamates
2015
The asymmetric synthesis of fluorinated isoindolinones has been achieved by a palladium-catalyzed aminocarbonylation reaction of the corresponding -fluoroalkyl o-iodobenzylamines. A base-mediated anti -hydride elimination process was suggested to explain the partial erosion of the optical purity observed in some cases. This mechanistic rationale enabled the minimization of this partial racemization by fine-tuning the pK(a) of the base.
Heteroforiju izmaiņas pēc ilgstošas disociācijas un prizmu adaptācijs testa
2021
Maģistra darbs ir uzrakstīts angļu valodā uz 46 lapām. Tas satur 14 attēlus, 8 tabulas un 80 atsauces uz literatūras avotiem. Mērķis bija izvērtēt verģences adaptācijas ietekmi uz heteroforiju novērtējumu un prizmu adaptācijas testa pielietojumu klīniskajā praksē. Pirmajā daļā 40 dalībniekiem tika novērtētas heteroforija izmaiņas 2 minūšu laikā pēc disociācijas. Otrajā daļā tika novērtēta verģences adaptācija, izmantojot prizmu adaptācijas testu. Rezultāti parādīja, ka heteroforijas lielumu būtiski ietekmē disociācijas ilgums. Dalībniekiem ar diagnosticētu verģences anomāliju novēroja samazinātu verģences adaptāciju. Secinājums: verģences adaptācijai ir nozīmīga ietekme uz heteroforijas nov…
Prevalence of visual impairment and refractive errors in an urban area of Mexico
2019
AIM: To determine the distribution of refractive errors in a school-age population in Quintana Roo (Mexico) in the framework of an international cooperation campaign for the prevention of blindness. METHODS: A sample of 2647 school-age children (ranging from 5 to 14 years old) with a mean age of 9.1±1.9 years old were tested by trained volunteers for distance visual acuity (VA) and refractive errors. The first screening examination included uncorrected distance visual acuity (UDVA) and VA with a +2.00 D lens. Inclusion criteria for a second complete cycloplegic eye examination performed by an optometrist were UDVA <20/25 (0.10 logMAR or 0.8 decimal) and/or VA with +2.00 D ≥20/25. RESULTS: A…
Microorganisms of food ice cubes and their transfer to drinks
2017
The present work was carried out to investigate the microbiological characteristics of the ice cubes produced at different levels: 1) home-made (HM) from domestic freezers; 2) produced by ice machines in bars and pubs (BP); 3) produced by ice industries (IN). BP samples were collected from the box stocks. HM and BP samples were transferred into sterile stomacher bags. IN samples were provided in the manufacturers’ plastic bags. Samples were transported into thermal insulated boxes. Five samples per each production level, forming a total of 15 samples (HM1-HM5, BP1-BP5, IN1-IN5), were collected in duplicate in two consecutive months. Each ice sample was thawed in 1 L sterile Dhuram’s bottle …
Diritto e immigrazione. Un quadro aggiornato delle questioni più attuali e rilevanti
2021
Il diritto dell’immigrazione, costantemente al centro del dibattito pubblico, si caratterizza per una continua evoluzione e richiede quindi un costante aggiornamento, tanto sotto il profilo dell’analisi normativa, quanto sotto quello giurisprudenziale e prasseologico. Lo speciale si propone di presentare un quadro aggiornato delle questioni più attuali e rilevanti concernenti la regolamentazione del fenomeno migratorio, secondo una prospettiva multidisciplinare, attenta sia agli aspetti teorici sia a quelli più strettamente pratici. In questa cornice si collocano gli studi mirati all’esame della giurisprudenza della Corte europea dei diritti dell’uomo e delle politiche eurounitarie, in un c…
Diagnosis of boron, fluorine, lead, nickel and zinc toxicity in citrus plantations in Villarreal, Spain
1997
In the late 1980s, citrus plantations in the area of Villarreal (Spain) showed injuries similar to those previously reported for boron and fluorine toxicity. The area was affected by the disposal of industrial wastewater, mainly from ceramic industries. Conjunctive uses of surface water, groundwater and wastewater for irrigation had taken place. A survey was conducted at 25 orchards to assess leaves and soil for their boron, fluorine, lead, nickel and zinc contents. Wastewater and groundwater were also analyzed to corroborate the presence of these pollutants. The results showed that both boron and fluorine contents were greater than those reported as excess at the most part of the orchards …
Self-Efficacy Between Previous and Current Mathematics Performance of Undergraduate Students: An Instrumental Variable Approach to Exposing a Causal …
2021
PurposeSelf-efficacy has been argued theoretically and shown empirically to be an essential construct for students’ improved learning outcomes. However, there is a dearth of studies on its causal effects on performance in mathematics among university students. Meanwhile, it will be erroneous to assume that results from other fields of studies generalize to mathematics learning due to the task-specificity of the construct. As such, attempts are made in the present study to provide evidence for a causal relationship between self-efficacy and performance with a focus on engineering students following a mathematics course at a Norwegian university.MethodThe adopted research design in the presen…
Simulation of Fatigue Delamination Growth in Composites with Different Mode Mixtures
2007
A numerical model, obtained by implementing a cyclic damage model in the framework of an interface element, is here proposed to reproduce the crack growth in laminated composites subjected to cyclically repeated loads. This model, which differs from the few studies in the literature on the topic, applies not only to single fracture modes but also to mixed modes, and to constant or variable crack growth rates. The applied load (in terms of force or displacement) is assumed to oscillate between a minimum and a maximum constant value. The Paris curve can be reproduced with accuracy once some parameters in the numerical model are tuned with experiments. These parameters are preliminarily found…
Four Career Stories from Doctoral Students to Doctoral Holders : Qualitative Longitudinal Examination
2023
Aims: Universities and their doctoral programs open a range of career opportunities for doctoral students and doctors. There is a need to problematize assumptions related to the construction of doctoral careers. This study addresses this need by examining the development of doctoral career paths and the factors influencing them from a qualitative longitudinal perspective. This study focuses on the narrative career stories of doctoral students and doctoral graduates from a temporal perspective and at the individual level.
 Study Design: The study was conducted as qualitative longitudinal research among Finnish doctoral students and later same persons as doctoral holders (N=9). The aim o…