61,187 research outputs found
An analytical demonstration of coupling schemes between magnetohydrodynamic codes and eddy current codes
No full textIn order to model a magnetohydrodynamic (MHD) instability that strongly couples to external conducting structures (walls and/or coils) in a fusion device, it is often necessary to combine a MHD code solving for the plasma response, with an eddy current code computing the fields and currents of conductors. We present a rigorous proof of the coupling schemes between these two types of codes. One of the coupling schemes has been introduced and implemented in the CARMA code {[}R. Albanese, Y. Q. Liu, A. Portone, G. Rubinacci, and F. Villone, IEEE Trans. Magn. 44, 1654 (2008); A. Portone, F. Villone, Y. Q. Liu, R. Albanese, and G. Rubinacci, Plasma Phys. Controlled Fusion 50, 085004 (2008)] that couples the MHD code MARS-F {[}Y. Q. Liu, A. Bondeson, C. M. Fransson, B. Lennartson, and C. Breitholtz, Phys. Plasmas 7, 3681 (2000)] and the eddy current code CARIDDI {[}R. Albanese and G. Rubinacci, Adv. Imaging Electron Phys. 102, 1 (1998)]. While the coupling schemes are described for a general toroidal geometry, we give the analytical proof for a cylindrical plasma
Finite linear spaces admitting a projective group PSU(3,q) with q even
No full textAbstractThis article is a contribution to the study of the automorphism groups of finite linear spaces. In particular we look at simple groups and prove the following theorem:Let G=PSU(3,q) with q even and G acts line-transitively on a finite linear space S. Then S is one of the following cases:(i)A projective plane;(ii)A regular linear space with parameters (b,v,r,k)=(q2(q2−q+1),q3+1,q2−q+1,q+1). This is called the Hermitian unitary design
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
Are Chinese loess deposits essentially continuous?
No full textWe conducted a paleomagnetic examination of the last glacial loess of three representative profiles along an east-west transect in the central Loess Plateau in order to assess the continuity of Chinese loess. The results show that the Xifeng and Luochuan profiles record the Laschamp geomagnetic excursion but with different morphologies. Together with the published results from Weinan, southern plateau, our results suggest that sedimentation of the last glacial loess in the central-southern plateau was continuous at the time scale equivalent to the duration of the Laschamp excursion (~2 kyr), but probably episodic at finer time scales (<2 kyr). No geomagnetic excursion was found at the Yichuan profile near the Yellow River valley, where loess accumulation may be strongly affected by local environmental changes and thus may have been discontinuous. Both site location and time scale therefore need to be considered when considering continuity of Chinese loess.<br/
Ophiorrhiza pseudonapoensis L. Wu & Q. R. Liu 2023, sp. nov.
No full textOphiorrhiza pseudonapoensis L. Wu & Q. R. Liu, sp. nov. (Figs. 1–3) Type:— China. Yunnan: Hekou county, Nanxi town, alt. 950 m, Ẵễ (Lei Wu) 4225 (holotype, CSFI076284!; isotypes, BNU!, CSFI076278!, CSFI076285!, CSFI076286!, CSFI076287!). Diagnosis:— Ophiorrhiza pseudonapoensis is similar to O. napoensis, but the former differs from the latter in having 5–10 (vs ca. 1) mm long stipules, persistent (vs caducous) bracts, oblanceolate (vs lanceolate-linear) bracts, homostylous (vs heterostylous) flowers, and ensiform (vs narrowly triangular) calyx lobes. The new species also resembles O. macrocarpa L. Wu & Q. R. Liu (2018: 2), but it can be distinguished from the latter by its 5–10 (vs less than 1) mm long stipules, oblanceolate (vs subulate or linear subulate) and 7–20 (vs less than 5) mm long bracts, and (1.2–)1.5–2(–2.5) (vs 0.4–0.6) mm long calyx lobes. Description:— Erect or suberect herbs, 25–35 cm tall; stem glabrous, often dark purplish when dry. Leaves usually in unequal pairs; petiole shorter than 1 cm, blade drying papery, dark greenish adaxially, greenish-yellow abaxially, lanceolate, oblanceolate, or ovate-lanceolate, 7–17(–21) × 2–4 cm, base cuneate, margin entire, apex acuminate, glabrous on both surfaces; secondary veins 9–12 on each side, both sides flat, clearly visible abaxially; stipules narrowly triangular, 5–10 mm long, apex acuminate, persistent. Inflorescences congested-cymose, terminal, erect, usually many flowered; peduncles 1–4 cm long; axes 0.3–2.5 cm long, helicoid, puberulent or subglabrous; bracts oblanceolate, 7–20 mm long, apex obtuse, glabrous. Flowers homostylous on 1–2 mm long pedicels. Calyx puberulent; lobes 5, ensiform, (1.2–)1.5–2(–2.5) mm long, with one gland at each sinus; hypanthium 1.2–1.5 × 2–2.5 mm, inconspicuously 5-ribbed. Corolla pale pink or white, drying yellow-brown, salverform, glabrous outside; tube 25–28 mm long, glabrous inside except puberulent at the throat; lobes 5, subovate, 4–5 × 3.5–4 mm, dorsally smooth, rostrate at apex. Stamens 5, attached to the throat of the corolla tube; anthers linear-oblong, ca. 2.0 mm long; filaments 1.5–2.2 mm long, glabrous; stigmas 0.5 mm long, sub-capitate, shallowly bilobed, reaching a little higher than anthers. Capsules mitriform or obcordate, ca. 3 × 9 mm. Seeds many, angular. Phenology:— Flowering from October to January of next year. Etymology:— The specific epithet is derived from its morphology that is closely resembling Ophiorrhiza napoensis. Distribution and Habitat:— Ophiorrhiza pseudonapoensis is only known from southeastern Yunnan until now. All individuals observed in the wild are distributed in limestone areas and grow in humid places, such as along stream banks, or sometimes on wet cliff under dense forest cover at altitudes of 500–1500 m. Conservation status:— So far, only two Ophiorrhiza pseudonapoensis populations in Maguan and Hekou with more than 1000 mature individuals were observed during our investigations. And the population we discovered from Maguan is in the Gulinjing provincial nature reserve, where habitats are in good condition and there are no threatening factors until now. According to the type specimens, we speculate that there are more than ten populations with more than 2000 mature individuals in total from southeastern Yunnan, and the distribution area is more than 30 km 2. Thus, this species is assigned a status of Least Concern (LC) following the guidelines of IUCN (2022). Additional specimens examined (paratypes):— CHINA. Yunnan: Maguan, X.T. Cai 51898 (IBSC), Y.J. Hu GS86-2101 (IBSC), Chen & Li 86SL-343 (IBSC, YSY), 86SL-7946 (IBSC, YSY), GL86-2051 (IBSC, YSY), GL86- 7558 (IBSC, YSY), GL86-7864 (IBSC, YSY), Y.M. Shui et al. 30216 (PE), 31119 (IBSC, PE), L. Wu. 4232 (BNU, CSFI); Xichou, A.Q. Wu 7761 (KUN), 7899 (KUN), without locality, Z.L. Lin 14031304 (KUN). Notes:— Flowers of Ophiorrhiza napoensis were described by Lo (1990) as “corolla tube 2–2.2 mm long, stamens inserted at the throat of corolla tube, stylus 1.3–1.4 cm long, stigma 2.5–3 mm long, 2-lobed”, and its biology was noted as “it might be homostylous” in the protologue. Through a careful observation of floral trait correlations, Kudoh et al. (2001) indicated that O. napoensis has both long- and short-styled morphs, viz. stigmas positioned at the throat while anthers located a little above the middle of the corolla tube in the long-styled form, and opposite in the short-styled form. However, in recent work, Tao & Taylor (2011) followed the description of Lo (1990) instead of Kudoh et al. (2001) and noted that the floral biology of this species as unknown. After several field investigations in Guangxi and Yunnan, southwestern China, we support the conclusion of Kudoh et al. (2001) that the flowers of O. napoensis are heterostylous (Fig. 4, C–I), and confirm the O. pseudonapoensis is a misidentification of O. napoensis. Ophiorrhiza pseudonapoensis is also similar to O. macrocarpa based on flower form and corolla shape but differs in having longer stipules (5–10 mm) (vs less than 1 mm in O. macrocarpa), longer bracts (7–20 mm long) (vs less than 5 mm), oblanceolate bracts (vs subulate or linear subulate), and much longer calyx lobes (1.2–2.5 mm long) (vs 0.4–0.6 mm long) (Fig. 4, A–C). More detailed comparisons among the three species are listed in Table 1.Published as part of Liu, Qin, Chen, Ao-Xue, Liao, Xiao-Wen, Liu, Quan-Ru & Wu, Lei, 2023, Ophiorrhiza pseudonapoensis (Rubiaceae), a new species from Yunnan, southwestern China, pp. 228-234 in Phytotaxa 607 (4) on pages 229-233, DOI: 10.11646/phytotaxa.607.4.1, http://zenodo.org/record/824332
Study of 1, 2-chlorine migration in (Alpha,alpha-dichlorobenzyl) chlorocarbene generated by laser flash photolysis of 3-chloro-3-(Alpha,alpha-dichlorobenzyl) diazirine
No full textPT: J; CR: BONNEAU R, 1989, J AM CHEM SOC, V111, P5973 GRAHAM WH, 1965, J AM CHEM SOC, V87, P4396 JONES M, 1973, CARBENES, V1 JONES M, 1975, CARBENES, V2 JONES WM, 1980, REARRANGEMENTS GROUN, V1 KIRMSE W, 1971, CARBENE CHEM LAVILLA JA, 1989, J AM CHEM SOC, V111, P6877 LIU MTH, IN PRESS J PHOTOCHEM LIU MTH, IN PRESS J PHYS ORG LIU MTH, 1987, CHEM DIAZIRINES LIU MTH, 1989, J AM CHEM SOC, V111, P6873 LIU MTH, 1990, J AM CHEM SOC, V112, P3915 LIU MTH, 1990, J CHEM SOC CHEM COMM, P1650 MORGAN S, 1991, J AM CHEM SOC, V113, P2782 MOSS RA, 1990, J AM CHEM SOC, V112, P5642 REGITZ M, 1989, METHODEN ORGANISCH E, V19 SCHAEFER HF, 1979, ACCOUNTS CHEM RES, V12, P288; NR: 17; TC: 4; J9: J ORG CHEM; PG: 3; GA: HN858Source type: Electronic(1
Formation of indolizines by the addition of α-chloroacrylonitrile to pyridinium ylides: regioselectivity and Hammett correlation
No full textPT: J; CR: BENSASSON R, 1971, T FARADAY SOC, V67, P1904 BONNEAU R, 1989, J CHEM SOC CHEM COMM, P510 CARMICHAEL I, 1986, J PHYS CHEM REF DATA, V15, P1 GRAHAM WH, 1965, J AM CHEM SOC, V87, P4396 LIU MTH, 1987, CHEM DIAZIRINES, CH5 LIU MTH, 1987, TETRAHEDRON LETT, P1011 PUGMIRE RJ, 1971, J AM CHEM SOC, V98, P1887 SOUNDARAJAN N, 1988, TETRAHEDRON LETT, P3419 TURRO NJ, 1980, J AM CHEM SOC, V102, P7578 UCHIDA T, 1976, SYNTHESIS-STUTTGART, P209; NR: 10; TC: 10; J9: J CHEM SOC PERKIN TRANS 1; PG: 2; GA: AL500Source type: Electronic(1
Cancellation of drift kinetic effects between thermal and energetic particles on the resistive wall mode stabilization
No full textDrift kinetic stabilization of the resistive wall mode (RWM) is computationally investigated using MHD-kinetic hybrid code MARS-K following the non-perturbative approach (Liu et al 2008 Phys. Plasmas 15 112503), for both reversed field pinch (RFP) and tokamak plasmas. Toroidal precessional drift resonance effects from trapped energetic ions (EIs) and various kinetic resonances between the mode and the guiding center drift motions of thermal particles are included into the self-consistent toroidal computations. The results show cancellation effects of the drift kinetic damping on the RWM between the thermal particles and EIs contributions, in both RFP and tokamak plasmas, even though each species alone can provide damping and stabilize RWM instability by respective kinetic resonances. The degree of cancellation generally depends on the EIs equilibrium distribution, the particle birth energy, as well as the toroidal flow speed of the plasma
Kinetic and spectroscopic properties of carbene-diazirine ylides
No full textThe formation of a metastable carbene-diazirine ylide (CDY), characterized by an UV absorption spectrum in the range of 270-290 nm and yielding azine by rearrangement, is shown to be a general process in the photolysis of diazirines. However, the yield of formation and the lifetime of CDY greatly depend on the system considered. The decreasing value of the rate constant of the reaction, carbene + diazirine --> CDY, from similar to 10(9) M-1 s(-1) for singlet dialkylcarbenes, Ad: (adamantylidene) and BCN: (bicyclo[3.3.1]non-9-ylidene), to similar to 10(8) M-1 s(-1) for benzylchlorocarbene and to similar to 10(6) M-1 s(-1) for cyclopropyl and phenylchlorocarbenes, reflects the decreasing reactivity of these carbenes. The lifetime of these ylides is determined by the value of the activation energy barrier for their rearrangement to azine, E-a approximate to 15.5 kcal/mol for dialkylcarbenes, approximate to 11.5 kcal/mol fur alkylchlorocarbenes, and <10 kcal/mol for phenylchlorocarbene. This decrease of E-a is related to the strong stabilization of the azine when proceeding from CR2=N-N=CR2 to Ph-CCl=N-N=CCl-Ph. Another mechanism for the formation of azine, by a second-order reaction of the diazo isomer of the diazirine, is clearly identified in the case of photolysis of the BCN(N-2) diazirine.PT: J; CR: BONNEAU R, 1989, J AM CHEM SOC, V111, P5974 BONNEAU R, 1992, J PHOTOCH PHOTOBIO A, V68, P97 BONNEAU R, 1997, PURE APPL CHEM, V69, P979 BONNEAU R, 1998, J PHOTOCH PHOTOBIO A, V116, P9 BRINKER UH, 1998, ADV CARBENE CHEM, V2 DOYLE MP, 1987, J ORG CHEM, V52, P1619 GRAHAM WH, 1965, J AM CHEM SOC, V87, P4396 JACKSON JE, 1988, J AM CHEM SOC, V110, P5595 LIU MTH, 1992, J AM CHEM SOC, V114, P3604 LIU MTH, 1992, J ORG CHEM, V57, P2483 LIU MTH, 1992, J PHOTOCH PHOTOBIO A, V63, P115 LIU MTH, 1994, INT J CHEM KINET, V26, P1179 LIU MTH, 1994, J PHOTOCH PHOTOBIO A, V84, P133 LIU MTH, 1994, RES CHEM INTERMEDIAT, V20, P195 LIUEAU R, 1989, J PHYS CHEM-US, V93, P7300 MERRER DC, 1998, J ORG CHEM, V63, P3010 MOSS RA, 1990, J AM CHEM SOC, V112, P1638 MOSS RA, 1990, J AM CHEM SOC, V112, P5642 OIDA S, 1967, CHEM PHARM BULL, V15, P545 OIDA S, 1968, CHEM PHARM BULL, V16, P654 SHUSTOV GV, 1999, CAN J CHEM, V77, P540 TURRO NJ, 1980, J AM CHEM SOC, V102, P7576; NR: 22; TC: 8; J9: J PHYS CHEM A; PG: 6; GA: 311EYSource type: Electronic(1
Insertion of phenylchlorocarbenes in the C-H bonds of alkanes: measurement of the rate constants by laser flash photolysis
No full textPhenylchlorocarbenes, produced by photolysis of the parent diazirines, have a very limited lifetime in alkane solvents. The rate of disappearance of p-methyl- and p-chlorophenylchlorocarbenes has been measured in iso-octane, cyclohexane and n-hexane as well as in benzene for comparison. The rate constants of several processes (dimerization, addition to the diazirine, reaction with the solvent, etc. ) contributing to the disappearance of the phenylchlorocarbenes have been determined. The rate of reaction with the solvent, which is much lower in benzene than in alkanes and depends strongly on the nature of the alkane, is assumed to be an insertion of the carbene in the C-H bonds of the solvent. Consequences of this reaction on the chemistry of carbenes produced by continuous irradiation (or thermolysis) of diazirines in alkanes are briefly discussed.PT: J; CR: BENSASSON R, 1971, T FARADAY SOC, V67, P1904 BONNEAU R, 1986, NOUV J CHIM, V10, P425 BONNEAU R, 1991, PURE APPL CHEM, V63, P289 DOYLE MP, 1988, TETRAHEDRON LETT, V29, P5863 GOULD IR, 1985, TETRAHEDRON, V41, P1587 GRAHAM WH, 1965, J AM CHEM SOC, V87, P4396 LIU MTH, 1987, CHEM DIAZIRINES LIU MTH, 1990, J CHEM SOC CHEM COMM, P1482 LIU MTH, 1992, J AM CHEM SOC, V114, P3604 LIU MTH, 1992, J ORG CHEM, V57, P2483 LIU MTH, 1992, J PHOTOCH PHOTOBIO A, V63, P115 LUTZ H, 1973, J PHYS CHEM-US, V77, P1758 MORGAN S, 1991, J AM CHEM SOC, V113, P2782 MOSS RA, 1990, J AM CHEM SOC, V112, P5642 MOSS RA, 1990, KINETICS SPECTROSCOP; NR: 15; TC: 11; J9: J PHOTOCHEM PHOTOBIOL A-CHEM; PG: 10; GA: JQ196Source type: Electronic(1
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