Search results for "Step"
showing 10 items of 509 documents
Two-Step Flow of Communication
2008
Ceremoniał za panowania dwóch pierwszych królów elekcyjnych doby pojagiellońskiej w świetle relacji rodzimych i cudzoziemskich
2020
W II poł. XVI w. drogi ustrojowe państw Europy zachodniej i Rzeczypospolitej zaczęły się coraz wyraźniej różnicować. W sprzyjających okoliczności mogło to budzić wzajemne zaciekawienie, którego owocem są zachowane do dzisiaj relacje podróżników i dyplomatów. Wymiana spostrzeżeń w czasach, w których umysł polskiego szlachcica nie był jeszcze zdominowany przez ksenofobię, ujawnia w równej mierze aprobatę, jak chłodny dystans, a niekiedy niechęć. Zestawienie rodzimych refleksji z wnioskami płynącymi z cudzoziemskich podróży do Polski w drugiej połowie XVI w. wzbogaca naszą wiedzę na temat wizerunku Rzeczypospolitej w czasach jej świetności. Jak zauważył Mirosław Sadowski, okres panowania pierw…
Novel acrylamido monomers with higher hydrophilicity and improved hydrolytic stability: I. Synthetic route and product characterization.
1996
The novel acrylamido monomer reported by our group (N-acryloylaminoethoxyethanol, AAEE; Chiari et al., Electrophoresis 1994, 15, 177-186), found to combine high hydrophilicity with extraordinary resistance to alkaline hydrolysis, has come under closer scrutiny due to unexpected and random autopolymerization while stored as a 1/1 v/v water solution at 4 degrees C (possibly due to a greater oxidability of the ether group). We have additionally found a unique degradation pathway of the monomer, called "1-6 H-transfer", by which the C1 (on the double bond site), by constantly ramming against the C6, next to the ether oxygen (O7, which in fact favors the transfer of the hydrogen atom by C1), pro…
Suppression of new particle formation from monoterpene oxidation by NO<sub>x</sub>
2014
Abstract. The impact of nitrogen oxides (NOx = NO + NO2) on new particle formation (NPF) and on photochemical ozone production from real plant volatile organic compound (BVOC) emissions was studied in a laboratory setup. At high NOx conditions ([BVOC] / [NOx] < 7, [NOx] > 23 ppb) new particle formation was suppressed. Instead, photochemical ozone formation was observed resulting in higher hydroxyl radical (OH) and lower nitrogen monoxide (NO) concentrations. When [NO] was reduced back to levels below 1 ppb by OH reactions, NPF was observed. Adding high amounts of NOx caused NPF to be slowed by orders of magnitude compared to analogous experiments at low NOx conditions ([NOx] ~300 ppt)…
Two-step spin crossover behaviour in the chiral one-dimensional coordination polymer [Fe(HAT)(NCS)2]∞
2015
Solvated and unsolvated forms of the complex [Fe(HAT)(NCS)2]∞·(nMeOH) (1) (n = 1.5, 0; HAT = 1,4,5,8,9,12-hexaazatriphenylene) were prepared. The structure of 1·(1.5MeOH), measured at 120 K, showed that this system crystallizes in the homochiral P43 tetragonal space group. The solid is constituted of stacks of one-dimensional coordination polymers running along c-axis. All the FeII centres have the same Λ or Δ conformation and are in the LS state at 120 K. In the range of temperatures 10–300 K the magnetic properties of 1·(1.5MeOH) shows the occurrence of reversible spin crossover behaviour. However, above ca. 310 K complete desolvation of 1·(1.5MeOH) to give 1 was observed from crystal str…
A two-step synthesis of new macrobicyclic aza-ligands starting from “trans”dioxocyclam as diprotected macrocycle
1997
Abstract A rapid and convenient synthesis of two small aza-cryptands containing a 1,4,8,11-tetraazacyclotetradecane backbone is reported. This strategy can be applied to the preparation of many other aza-cages by varying the nature of the cross linker. Moreover, the two remaining secondary amine sites may allow the functionalization of these ligands or their grafting on a polymer.
Direct acid-catalysed mechanical depolymerisation of fibre sludge to reducing sugars using planetary milling
2016
Abstract This study performed a direct solvent-free acid-catalysed mechanical depolymerisation of fibre sludge to reducing sugars which involves one step of acid milling in a planetary mill. The common reported ‘solvent-free’ mechanocatalytic depolymerisation of lignocellulose which includes 1) acid impregnation, 2) vacuum evaporation and 3) mechanocatalytic depolymerisation was also performed as a reference. The major converted monosaccharides were determined by capillary electrophoresis and the results of total reducing sugar (TRS) yields were carried out based on the 3,5-dinitrosalicylic acid (DNS) method. The results showed that the TRS conversion of direct acid-catalysed mechanical dep…
Studies on the Mechanism of Inhibition by Phosphinothricin of Glutamine Synthetase Isolated from Triticum aestivum L.
1986
Summary The activity of glutamine synthetase (EC 6.3.1.2) isolated from roots and leaves of wheat is strongly inhibited by phosphinothricin. As revealed by gel filtration and kinetic studies the mechanism of inhibition appears to be irreversible. The results indicate that the rate limiting step of the reaction of the inhibitor with the chloroplast glutamine synthetase is not the initial, but the following reaction. However, of root glutamine synthetase the irreversible inhibition follows a second order reaction depending on the concentration of the enzyme and of phosphinothricin and the rate limiting step is the formation of the initial enzyme-inhibitor complex. According to the kinetic dat…
Step-growth Polymerization ofBistriazolinediones with1,1-Diphenylethylene
1996
The reactions of 4-ethyl-1,2,4-triazoline-3,5-dione (ETD) (1) and 4-phenyl-1,2,4-triazoline-3,5-dione (PhTD) (2) with 1,1-diphenylethylene (DPE) (3) were investigated at room temperature. The reactions are very fast and are completed in less than 4 min. These reactions lead to the formation of two 2 :1 adducts via double Diels-Alder and Diels-Alder-ene reactions in a ratio of 1.35 : 1. The structure of these adducts where R = Et were determined by X-ray analysis of a single crystal. These compounds were used as models for the polymerization reactions. The reaction of bistriazolinediones (1,6-bis-(3,5-dioxo-1,2,4-triazoline-4-yl)hexane and bis-(p-3,5-dioxo-1,2,4-triazoline-4-ylphenyl)methane…
ChemInform Abstract: trans- and cis-Bicyclo(n.1.0)alk-2-ynes of Medium Ring Size.
2010
Starting from cycloalkenes, the cis- or trans-cyclopropano anellated cycloalkynes 2–7 of medium ring size were synthesized. The triple bonds were introduced in the final reaction step either by the fragmentation of the corresponding 1,2,3-selenadiazoles or by direct dehydration of a ketone (Scheme 2). The cis-fused bicycles 2 and 3 and the trans-fused bicycles 5, 6 and 7 could be isolated in a pure state. The intermediary existence of the most strained system trans-bicyclo[7.1.0]dec-2-yne (4) was proven by trapping reactions.