2061. |
2062. |
2063. Taming the topology of calix[4]arene-based 2D-covalent organic frameworks : interpenetrated vs noninterpenetrated frameworks and their selective removal of cationic dyesBikash Garai, Dinesh Shetty, Tina Škorjanc, Felipe Gándara, Nawavi Naleem, Sabu Varghese, Sudhir Kumar Sharma, Maria Baias, Ramesh Jagannathan, Mark Anthony Olson, 2021, original scientific article Abstract: A bowl-shaped calix[4]arene with its exciting host–guest chemistry is a versatile supramolecular building block for the synthesis of distinct coordination cages or metal–organic frameworks. However, its utility in the synthesis of crystalline covalent organic frameworks (COFs) remains challenging, presumably due to its conformational flexibility. Here, we report the synthesis of a periodic 2D extended organic network of calix[4]arenes joined by a linear benzidine linker via dynamic imine bonds. By tuning the interaction among neighboring calixarene units through varying the concentration in the reaction mixture, we show the selective formation of interpenetrated (CX4-BD-1) and non-interpenetrated (CX4-BD-2) frameworks. The cone-shaped calixarene moiety in the structural backbone allows for the interweaving of two neighboring layers in CX4-BD-1, making it a unique example of interpenetrated 2D layers. Due to the high negative surface charge from calixarene units, both COFs have shown high performance in charge-selective dye removal and an exceptional selectivity for cationic dyes irrespective of their molecular size. The charge distribution of the COFs and the resulting selectivity for the cationic dyes were further investigated using computational methods.
Keywords: dyes and pigments, covalent organic frameworks, adsorption, layers, chemical structure
Published in RUNG: 16.03.2021; Views: 2232; Downloads: 0
This document has many files! More... |
2064. |
2065. |
2066. Influence of very large spatial heterogeneity on estimates of sea-level trendsAlexander Shapoval, Jean-Louis Le Mouël, Vincent Courtillot, M. Shnirman, 2020, original scientific article Abstract: We propose a new method to estimate sub-decadal to centennial time scales of sea-level change. Since the coastal data exhibit large spatial heterogeneity and temporal variability, the global sea-level rate is estimated as an appropriate average of the rates observed at available locations and computed with sliding windows. We claim that under such heterogeneity the median serves as a better representative of an adequate average than the mean. With this approach, the sea-level rate in 60 to 70 yr windows over the past century is found to be smaller than 1.7-1.9 mm/yr. These upper estimates are in line with those obtained with a scarce list of available long quasi-gapless series
Keywords: sea-level rise, median, sliding window, statistically significant trend
Published in RUNG: 16.03.2021; Views: 1890; Downloads: 0
This document has many files! More... |
2067. Delo jezikovnega asistenta za slovenščino v okviru manjšinskega srednješolskega izobraževanja na TržaškemKatarina Gomboc Čeh, 2020, independent scientific component part or a chapter in a monograph Abstract: V šolskem letu 2018/2019 je bilo prvič razpisano mesto jezikovnega asistenta za slovenščino na višjih srednjih šolah s slovenskim učnim jezikom v Trstu. Članek izhaja iz izkušenj avtorice, jezikovne asistentke za slovenščino v šolskih letih 2018/2019 in 2019/2020. V prvem delu utemeljuje vlogo jezikovnega asistenta za slovenščino v okviru manjšinskega srednješolskega izobraževanja na Tržaškem, nato pa na podlagi orisa sociolingvistične situacije ponuja nastavke didaktičnih pristopov in možnosti za razvijanje sporazumevalne zmožnosti v slovenskem knjižnem jeziku na višjih srednjih šolah s slovenskim učnim jezikom na Tržaškem.
Keywords: slovenščina, pouk slovenščine, manjšinsko šolstvo, slovenska šola v Italiji, učni jezik, jezikovni asistent, sporazumevalna zmožnost
Published in RUNG: 16.03.2021; Views: 2170; Downloads: 0
This document has many files! More... |
2068. |
2069. |
2070. Implicative falling neutrosophic ideals of BCK-algebrasXiao Long Xin, Hashem Bordbar, Florentin Smarandache, Rajab Ali Borzooei, Young Bae Jun, 2021, original scientific article Abstract: The notions of an implicative (2; 2)-neutrosophic ideal and an implicative falling neutrosophic ideal are
introduced, and several properties are investigated. Characterizations of an implicative (2; 2)-neutrosophic ideal
are considered, and relations between an implicative (2; 2)-neutrosophic ideal and an (2; 2)-neutrosophic ideal are
discussed. Conditions for an (2; 2)-neutrosophic ideal to be an implicative (2; 2)-neutrosophic ideal are provided,
and relations between an implicative (2; 2)-neutrosophic ideal, a falling neutrosophic ideal and an implicative falling
neutrosophic ideal are studied. Conditions for a falling neutrosophic ideal to be implicative are provided. Relations
between implicative falling neutrosophic ideal, commutative falling neutrosophic ideal and positive implicative falling
neutrosophic ideal are discussed.
Keywords: neutrosophic random set, neutrosophic falling shadow, (positive implicative) (2, 2)-neutrosophic ideal, (positive implicative) falling neutrosophic ideal, (commutative) (2, 2)-neutrosophic ideal, (commutative) falling neutrosophic ideal
Published in RUNG: 15.03.2021; Views: 2068; Downloads: 0
This document has many files! More... |
