60,838 research outputs found
INNOVATIVE PILLAR[6]ARENE-BASED STATIONARY PHASES FOR HIGH-RESOLUTION GAS CHROMATOGRAPHIC ANALYSES
No full textIn this work, the synthesis, fabrication, and characterization of new stationary phases based on pillar[6]arene derivative modified by long alkyl chains (P6A-C10) for high-resolution gas chromatographic (GC) analyses are reported. Pillar[n]arenes are a new class of macrocyclic hosts that can accommodate specific guests due to their highly symmetrical and rigid pillar architectures with π-electron rich cavities. Quantum chemistry calculations have been performed, showing a difference in non-covalent interactions with the P6A-C10 pillar framework, which leads to specific selectivity for aromatic compounds. The GC columns prepared with these innovative stationary phases exhibited a medium polarity, and good reproducibility for run-to-run, day-to-day, and column-to-column analyses [1], demonstrating great potential as new stationary phases in separation science. Furthermore, peculiar advantages are achieved if compared with the commercial HP-5, HP-35, DB-17, and PEG-20M columns, showing unmatched resolving capabilities toward chloroaniline, bromoaniline, iodoaniline, toluidine, and xylene isomers [2].
References:
1. Sun, T., Chen, R., Huang, Q., Ba, M., Cai, Z., Hu, S., Liu, X., Nardiello, D., & Quinto, M., ACS Appl. Mater. Interfaces 14 (2022) 56132−56142.
2. Sun, T., Chen, R., Huang, Q., Ba, M., Cai, Z., Chen, H., Qi, Y., Chen, H., Liu, X., Nardiello, D., & Quinto, M., Anal. Chim. Acta 1251 (2023) 340979
Simulation of thermal plant optimization and hydraulic aspects of thermal distribution loops for large campuses
No full textFollowing an introduction, the author describes Texas A&M University and its utilities system. After that, the author presents how to construct simulation models for chilled water and heating hot water distribution systems. The simulation model was used in a $2.3 million Ross Street chilled water pipe replacement project at Texas A&M University. A second project conducted at the University of Texas at San Antonio was used as an example to demonstrate how to identify and design an optimal distribution system by using a simulation model. The author found that the minor losses of these closed loop thermal distribution systems are significantly higher than potable water distribution systems. In the second part of the report, the author presents the latest development of software called the Plant Optimization Program, which can simulate cogeneration plant operation, estimate its operation cost and provide optimized operation suggestions. The author also developed detailed simulation models for a gas turbine and heat recovery steam generator and identified significant potential savings. Finally, the author also used a steam turbine as an example to present a multi-regression method on constructing simulation models by using basic statistics and optimization algorithms. This report presents a survey of the author??s working experience at the Energy Systems Laboratory (ESL) at Texas A&M University during the period of January 2002 through March 2004. The purpose of the above work was to allow the author to become familiar with the practice of engineering. The result is that the author knows how to complete a project from start to finish and understands how both technical and nontechnical aspects of a project need to be considered in order to ensure a quality deliverable and bring a project to successful completion. This report concludes that the objectives of the internship were successfully accomplished and that the requirements for the degree of Degree of Engineering have been satisfied
Kwoniella shandongensis R. Chen, Yuan M. Jiang & S. C. Wei ex M. Groenew. & Q. M. Wang 2020, sp. nov.
No full text<p> <i>Kwoniella shandongensis</i> R. Chen, Yuan M. Jiang & S.C. Wei ex M. Groenew. & Q.M. Wang, <i>sp. nov.</i> MycoBank MB828750.</p> <p>For description see Int. J. Syst. Evol. Microbiol. 62: 2775 (2012).</p> <p> <i>Holotype:</i> CGMCC 2.04458 (preserved in a metabolically inactive state).</p> <p> <i>Synonyms</i>: <i>Kwoniella shandongensis</i> Chen <i>et al.</i>, Int. J. Syst. Evol. Microbiol. 62: 2775 (2012), <i>nom. inval.</i>, Art. 40.7 (Shenzhen).</p>Published as part of <i>Li, A. - H., Yuan, F. - X., Groenewald, M., Bensch, K., Yurkov, A. M., Li, K., Han, P. - J., Guo, L. - D., Aime, M. C., Sampaio, J. P., Jindamorakot, S., Turchetti, B., Inacio, J., Fungsin, B., Wang, Q. - M. & Bai, F. - Y., 2020, Diversity and phylogeny of basidiomycetous yeasts from plant leaves and soil: Proposal of two new orders, three new families, eight new genera and one hundred and seven new species, pp. 17-140 in Studies In Mycology 96</i> on page 134, DOI: 10.1016/j.simyco.2020.01.002, <a href="http://zenodo.org/record/10497182">http://zenodo.org/record/10497182</a>
ISOMER SEPARATIONS BY INNOVATIVE GAS CHROMATOGRAPHY STATIONARY PHASES
No full textThe chromatographic separation of aromatic amines and xylenes isomers represents a big issue in chemical and petroleum industries, owing to their high similarity in terms of molecular sizes, polarity, and boiling points: as a result, commercial columns very often do not allow their complete peak separation. For this reason, several typologies of materials with different structures and properties have been developed and proposed as gas chromatography stationary phases in recent years. Macrocycles and ionic liquid-based chain-typed copolymers have emerged, due to their special chromatographic selectivity and separation mechanisms, resulting from their three-dimensional structures and outstanding thermal stability. Very recently, innovative stationary phases based on functionalized calixarene-polyethylene glycol (C4A-mPEG) [1], and amphiphilic triblock copolymer bonded with benzimidazolium ionic liquid (TCP-Bim) [2] were designed, characterized, and used for GC separations of aromatic isomers. The separation features of the C4A-mPEG stationary phase, resulting from multiple molecular recognition processes with analytes, including π-π, H-bonding, dipole-dipole, and van der Waals interactions, allowed to obtain high-resolution performances for a wide range of compounds and their isomers, especially benzaldehydes, phenols, and anilines. Moreover, compared with 4-tertbutyl calix[4]arene (C4A) and polyethylene glycol (PEG) stationary phases, a higher resolving capability was also observed for the separation of toluidine and xylidine isomers. The separation capabilities of the TCP-Bim columns are attributable to different analyte-stationary phase interaction mechanisms, arising from the particular TCP-Bim structure that combines ionic liquid and copolymer peculiarities, showing stronger retention towards aromatic compounds. The high-resolution capabilities of the TCP-Bim column were also tested with different aliphatic cis-/trans-isomers; the excellent separation performances for analytes with very similar properties demonstrated the good potential of these innovative materials as new classes of stationary phases for high-resolution GC separations.
References:
1. Chen, R., Cai, Z., Li, W., Huang, Q., Nardiello, D., Quinto, M., Liu, X., Hu, S., & Sun, T., Chem. Biodiversity 19 (2022) e202200829.
2. Huang, Q., Cai, Z., Chen, R., Zhang, W., Nardiello, D., Quinto, M., Liu, X., Hu, S., & Sun, T., Microchemical Journal 183 (2022) 108084
Estudo variacional do modelo de Moszkowski-q-deformado
No full textDissertação (Mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas.A validade da utilização do método variacional via estados coerentes q-deformados e aqui testada, no contexto das álgebras quânticas, para dois diferentes tipos de modelos, o de Lipkin e o de Moszkowski. O comportamento da transição de fase sob o efeito da deformação e também observado nos dois modelos acima. Há várias maneiras diferentes de se deformar quanticamente um sistema. Nessa dissertação duas dessas maneiras são estudadas em detalhe, e suas diferenças são apontadas
q-Differential equations for q-classical polynomials and q-Jacobi-Stirling numbers
No full textWe introduce, characterise and provide a combinatorial interpretation for the so-called q-Jacobi–Stirling numbers.
This study is motivated by their key role in the (reciprocal) expansion of any power of a second order
q-differential operator having the q-classical polynomials as eigenfunctions in terms of other even order operators,
which we explicitly construct in this work. The results here obtained can be viewed as the q-version of
those given by Everitt et al. and by the first author, whilst the combinatorics of this new set of numbers is a
q-version of the Jacobi–Stirling numbers given by Gelineau and the second author
High-Q TM whispering-gallery modes in three-dimensional microcylinders
No full textWe present a generation condition for realizing high-Q TM whispering-gallery modes (WGMs) in semiconductor microcylinders. For microcylinders with symmetry or weak asymmetry vertical waveguiding, we show that TM WGMs can have a high Q factor, with the magnitude of 10(4) at the radius of the microcylinder of 1 mu m, by three-dimensional numerical simulation. The Q factor of TE WGMs is much less than that of TM WGMs in the semiconductor microcylinders due to a vertical radiation loss caused by mode coupling with the vertical propagating mode. The results open up a possible application of TM WGMs in semiconductor microcylinders for efficient current injection microlasers and single photon sources
Didymella coffeae-arabicae Q. Chen
No full text<p> <i>Didymella coffeae-arabicae</i> (M. M. Aveskamp et al.) Q. Chen et al., Studies in Mycology. 82: 175. 2015 a</p> <p>Description.</p> <p>see Aveskamp et al. (2009).</p> <p>Materials examined.</p> <p> China, Yunnan Province, Puer City, Jingdong Yizu Autonomous County, from healthy leaves of <i>C. sinensis</i> cv. <i>Longjing 43</i>, 13 Jun 2020, Y. C. Wang, culture YCW 1972.</p> <p>Notes.</p> <p> <i>Didymella coffeae-arabicae</i> was introduced as <i>Phoma coffeae-arabicae</i> before the comprehensive revision of Didymellaceae (Chen et al. 2015 a). The sexual morph of <i>D. coffeae-arabicae</i> was reported by Samaradiwakara et al. (2023). It forms pseudo-sclerotioid chlamydospores and is easily recognised by its conspicuously wide ostiole and is phylogenetically related to a group that mainly comprises <i>Peyronellaea</i> species forming alternarioid-botryoid chlamydospores (Aveskamp et al. 2009). <i>Didymella coffeae-arabicae</i> caused leaf cankers of <i>Castanea mollissima</i> in China (Jiang et al. 2021). In the present study, one isolate from healthy tea plant leaves grouped with <i>D. coffeae-arabicae</i> with high statistical support (Fig. 2). This is the first report of <i>D. coffeae-arabicae</i> isolated from <i>C. sinensis</i>.</p>Published as part of <i>Wang, Yuchun, Tu, Yiyi, Chen, Xueling, Jiang, Hong, Ren, Hengze, Lu, Qinhua, Wei, Chaoling & Lv, Wuyun, 2024, Didymellaceae species associated with tea plant (Camellia sinensis) in China, pp. 217-251 in MycoKeys 105</i> on pages 217-251, DOI: 10.3897/mycokeys.105.11953
Existence of APAV(q,k) with q a prime power ≡5(mod8) and k≡1(mod4)
No full textAbstractStinson introduced authentication perpendicular arrays APAλ(t,k,v), as a special kind of perpendicular arrays, to construct authentication and secrecy codes. Ge and Zhu introduced APAV(q,k) to study APA1(2,k,v) for k=5, 7. Chen and Zhu determined the existence of APAV(q,k) with q a prime power ≡3(mod4) and odd k>1. In this article, we show that for any prime power q≡5(mod8) and any k≡1(mod4) there exists an APAV(q,k) whenever q>((E+E2+4F)/2)2, where E=[(7k−23)m+3]25m−3, F=m(2m+1)(k−3)25m and m=(k−1)/4
Constant mean curvature foliation of globally hyperbolic (2 + 1)-spacetimes with particles
No full textLet M be a globally hyperbolic maximal compact 3-dimensional spacetime locally modelled on Minkowski, anti-de Sitter or de Sitter space. It is well known that M admits a unique foliation by constant mean curvature surfaces. In this paper we extend this result to singular spacetimes with particles (cone singularities of angles less than π along time-like geodesics)
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