54,365 research outputs found
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
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
1/m(Q) corrections to form factors and extraction of vertical bar V-cb vertical bar
No full textForm factors for 0(-) --> 0(-) and 0(-) --> 1(-) mesonic transitions in the heavy quark limit and the 1/m(Q) corrections are analyzed model independently within the Bethe-Salpeter (BS) formalism. The analysis shows that the BS formalism has spin-flavor symmetry in the heavy quark limit and respects Luke's theorem when the 1/m(Q) corrections are taken into account. All form factors for B-->D(*) transitions beyond the zero recoil point are estimated in a relativistic constituent quark model based on the BS formalism. Using these form factors we calculate the branching ratios for the semileptonic decays B --> D(*)l(+)v(l) and extract the Cabibbo-Kobayashi-Maskawa matrix element \V-cb\. We get \V-cb\ = 0.042 +/- 0.003 which is consistent with the current world average.Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)1ARTICLE74146-41515
New performing GC columns with unmatched separation capabilities
No full textGas chromatography (GC) is widely used for qualitative and quantitative analysis in numerous fields, such as petroleum, chemical industry, agriculture, environmental protection, medicine, and so on, due to its high
versatility, high selectivity, simplicity of use, analysis speed, and low sample consumption. The column is the heart of a GC instrumentation, which allows the analyte separation and their recognition and quantification. Commercial columns do not always allow a complete peak separation when compounds (i.e., isomers) are very
similar in molecular weight, polarity, and vapor pressure. The choice of the correct stationary phase, with high selectivity towards target analytes, is the key to obtaining the required chromatographic separation and the subsequent qualitative and quantitative analysis.
Considering the rapid polymer science development and the growing demand for new columns with
improved resolution capabilities, in this work novel stationary phases for capillary GC have been designed, synthesized, and characterized in terms of polarity range, resolution, column efficiency, thermal stability, filmforming properties, and support-deactivating capacity1-5. The separation features of these novel stationary phases allow high-resolution performances for a wide range of compounds, like aromatic anilines, xylenes, aromatic amines, halogenated benzenes, and aromatic aldehydes, with marked capabilities toward isomer separations.References:
[1] T. Sun, M. Ba, Y. Song, W. Li, Y. Zhang, Z. Cai, S. Hu, X. Liu, D. Nardiello, M. Quinto, Analytica Chimica Acta, 2024, 1291, art. no. 342221.
[2] T. Sun, R. Chen, Q. Huang, M. Ba, Z. Cai, H. Chen, Y. Qi, H. Chen, X. Liu, D. Nardiello, M. Quinto, Analytica
Chimica Acta, 2023, 1251, art. no. 340979.
[3] T. Sun, R. Chen, Q. Huang, M. Ba, Z. Cai, S. Hu, X. Liu, D. Nardiello, M. Quinto, ACS Applied Materials and Interfaces, 2022, 14 50, pp. 56132-56142
[4] R. Chen, Z. Cai, W. Li, Q. Huang, D. Nardiello, M. Quinto, X. Liu, S. Hu, T. Sun, Chemistry and Biodiversity, 2022,
19, art. no. e202200829
[5] Q. Huang, Z. Cai, R. Chen, W. Zhang, D. Nardiello, M. Quinto, X. Liu, S. Hu, T. Sun, Microchemical Journal, 2022,
183, art. no. 10808
Roussoella neopustulans D. Q. Dai, J. K. Liu & K. D. Hyde 2014, sp. nov.
No full textRoussoella neopustulans D.Q. Dai, J.K. Liu & K.D. Hyde, sp. nov. FIG. 8 Index Fungorum: IF550664 Etymology. Similar to the species Roussoella pustulans, but ascospores are smaller. Saprobic on decaying bamboo culms. Ascostromata 0.5−1 mm diam, forming under raised, visible, black, dome-shape areas on host surface and becoming tumefied on maturity. Locules 70−100 µm high, 250−400 µm diam., solitary to gregarious, subglobose to ellipsoidal, dark brown, with an inconspicuous central ostiole. Peridium comprising host and fungal tissues, thin, 7−10 µm wide, composed of dark brown cells of textura angularis. Hamathecium comprising 1−1.5 µm wide, numerous, anastomosing branched cellular pseudoparaphyses, rough-walled, and embedded in a gelatinous matrix. Asci 80−95(−101) × 5.5−6.5 µm (x = 87.5 × 6.7 µm, n = 20), 6−8-spored, bitunicate, cylindrical, with a short knob-like pedicel, with an ocular apical chamber. Ascospores (8−)11−12.5(−14) × (7−)3.5−4.5 µm (x = 11.5 × 4 µm, n = 30), uni-seriate, ellipsoid to broad fusiform, 2-celled, upper cells bigger, occasionally curve, constricted at the septum, narrowly at both ends, with longitudinal striations. Asexual morph not produced in culture. Specimen examined THAILAND, Chiang Rai Province, Mae Fah Luang University, on dead culm of Bamboo, 1 August 2011, D. Q . Dai, DDQ0090 (holotype MFLU 13−0639, ex-type living culture MFLUCC 11−0609). Notes: Roussoella neopustulans is morphogically similar to R. pustulans, but differs in having smaller ascospores (11−12.5 × 3.5−4.5 µm vs. 10–16 × 4–5 µm) and larger asci (80−95 × 5.5−6.5 µm vs. 68–83 × 6.5–8.5 µm). In R. neopustulans the ascospore striations extend along the entire length and are linear, while those in R. pustulans are shorter and irregular (Hyde 1997). Roussoella neopustulans is phylogenetically distinct (FIGS. 1, 2) from R. pustulans (MAFF 239638). Roussoella neopustulans is also a phylogenetically distinct from R. siamensis (FIGS. 1, 2), but they are difficult to distinguish morphologically.Published as part of Liu, Jian-Kui, Phookamsak, Rungtiwa, Dai, Dong-Qin, Tanaka, Kazuaki, Jones, Gareth, Xu, Jian-Chu, Chukeatirote, Ekachai & Hyde, Kevin D., 2014, Roussoellaceae, a new pleosporalean family to accommodate the genera Neoroussoella gen. nov., Roussoella and Roussoellopsis, pp. 1-33 in Phytotaxa 181 (1) on page 15, DOI: 10.11646/phytotaxa.181.1.1, http://zenodo.org/record/514566
Characterization of maize roothairless6 which encodes a D-type cellulose synthase and controls the switch from bulge formation to tip growth
No full textCitation: Li, L., Hey, S., Liu, S. Z., Liu, Q., McNinch, C., Hu, H. C., . . . Hochholdinger, F. (2016). Characterization of maize roothairless6 which encodes a D-type cellulose synthase and controls the switch from bulge formation to tip growth. Scientific Reports, 6, 12. doi:10.1038/srep34395Root hairs are tubular extensions of the epidermis. Root hairs of the monogenic recessive maize mutant roothairless 6 (rth6) are arrested after bulge formation during the transition to tip growth and display a rough cell surface. BSR-Seq in combination with Seq-walking and subsequent analyses of four independently generated mutant alleles established that rth6 encodes CSLD5 a plasma membrane localized 129 kD D-type cellulose synthase with eight transmembrane domains. Cellulose synthases are required for the biosynthesis of cellulose, the most abundant biopolymer of plant cell walls. Phylogenetic analyses revealed that RTH6 is part of a monocot specific clade of D-type cellulose synthases. D-type cellulose synthases are highly conserved in the plant kingdom with five gene family members in maize and homologs even among early land plants such as the moss Physcomitrella patens or the clubmoss Selaginella moellendorffii. Expression profiling demonstrated that rth6 transcripts are highly enriched in root hairs as compared to all other root tissues. Moreover, in addition to the strong knock down of rth6 expression in young primary roots of the mutant rth6, the gene is also significantly down-regulated in rth3 and rth5 mutants, while it is up-regulated in rth2 mutants, suggesting that these genes interact in cell wall biosynthesis
Exotic tetraquark states with the qq (Q)over-bar(Q)over-bar configuration
No full textIn this work, we study systematically the mass splittings of the qq (Q) over bar(Q) over bar (q = u, d, s and Q = c, b) tetraquark states with the color-magnetic interaction by considering color mixing effects and estimate roughly their masses. We find that the color mixing effect is relatively important for the J(P) = 0(+) states and possible stable tetraquarks exist in the nn (Q) over bar(Q) over bar (n = u, d) and ns (Q) over bar(Q) over bar systems either with J = 0 or with J = 1. Possible decay patterns of the tetraquarks are briefly discussed.National Natural Science Foundation of China [11175073, 11275115, 11222547, 11261130311]; 973 program; National Program for Support of Top-notch Young Professionals; Fundamental Research Funds for the Central UniversitiesSCI(E)ARTICLE107
Gastrochilus wenshanensis Q. Liu, D. P. Ye & X. H. Jin
No full textGastrochilus wenshanensis Q. Liu, D.P. Ye & X.H. Jin, sp nov. (Ẋψfiffi±) (Figure 4–5) Type:— CHINA. Yunnan Province: Wenshan Zhuang-Miao Autonomous Prefecture, Malipo County, Xiajinchang Village, limestone forest, 2155 m, 16 June 2016, Qiang Liu 342 (holotype: HITBC0056874!). Morphologically, it is similar to Gastrochilus tsii for having a pendulous and branched stem and a fleshy and glabrous epichile, but differs from the latter by the yellow-green flowers, petals oblanceolate with an acute apex, the slightly erose margin of the epichile, and the absence of purple stripes along the margin of the hypochile. Description:— Epiphytic herbs. Stem pendulous, 12–18 cm long, with 0.4–0.6 cm internodes, slender, often branched. Leaves alternate, distichous, ovate, 1.3–1.6 × 0.4–0.7 cm; apex acuminate and unequally 2-lobed with 1 awn (young leaf). Inflorescences several, opposite to leaves, subumbellate, 4–6-flowered; peduncle 1.6–2.7 cm long, slender, upper part enlarged, lower part with 2 sheaths; floral bracts ovate-lanceolate, ca. 1.5 mm long; pedicel and ovary 3.2–4.0 mm long. Flowers yellow-green. Dorsal sepal oblong-elliptic, concave, 3.0–3.2 × 2.0– 2.2 mm, apex acute. Lateral sepals similar to dorsal sepal, 3.8–4.0 × 2.0– 2.2 mm, apex acute. Petals oblanceolate, 3.5–3.8 × 1.6–1.8 mm, apex acute. Lip with an epichile and a saccate hypochile; epichile sub-triangular, 2.5–2.8 × 5.0– 5.2 mm, fleshy, yellowish, adaxially glabrous, margin slightly erose, apex rounded; hypochile nearly cupular, with 3-ridges externally, 4.0– 4.5 mm tall, 4.0– 4.2 mm in diameter. Column stout with purple spots, ca. 1.0 mm; rostellum bilobed with acuminate apex; pollinia 2, subglobose, ca. 0.3 mm in diameter; stipe elongate, ca. 1.2 mm; viscidium elliptic, thick and bilobed; anther cap galeate with recurved–acuminate apex, 1.5 × 1.2 mm; Capsules not seen. Distribution and ecology:— This new species occurs in Malipo County, Yunnan Province, China. It grows on the rock at altitudes from 2055 to 2155 m in the limestone broad-leaved forests. Gastrochilus wenshanensis was observed flowering from June to July in the wild. Etymology:—Referring to the type locality, Wenshan Zhuang-Miao Autonomous Prefecture, Yunnan Province, China. Additional specimens examined(paratype):— CHINA: Yunnan Province: Wenshan MiaoAutonomous Prefecture, Malipo County, Xiajinchang Village, limestone forest, 2055 m, 16 June 2016, Qiang Liu 375 (HITBC 0056905!). Taxonomic discussion:— According to the characteristic of the long and pendulous stem, G. wenshanensis can be placed in section Microphyllae (Tsi 1996). However, some species were isolated from section Microphyllae by having dense hairs on the epichile, and clustered into clade V (Liu et al. 2019). While, other species with glabrous epichile were clustered into clade IV and new species of G. tsii and G. wenshenensis should be placed in this clade.Published as part of Liu, Qiang, Wu, Xun-Feng, Zhou, Shi-Shun, Li, Jian-Wu & Jin, Xiao-Hua, 2023, New species and record of Gastrochilus (Orchidaceae, Aeridinae) from China and Laos, pp. 210-224 in Phytotaxa 585 (3) on page 216, DOI: 10.11646/phytotaxa.585.3.3, http://zenodo.org/record/769080
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
FIGURE 6. Gastrochilus labrosus Q. Liu & X.H in New species and record of Gastrochilus (Orchidaceae, Aeridinae) from China and Laos
No full textFIGURE 6. Gastrochilus labrosus Q. Liu & X.H. Jin, sp nov. A. Habitat. B. Plant with flowers and fruits. C. Inflorescence. D & L. Abaxial and adaxial leaf. E. Flower. F. Sepals and petals. G & H. Front and lateral view of labellum. I. Back view of lip. J. Pollinarium. K. Anther cap.Published as part of Liu, Qiang, Wu, Xun-Feng, Zhou, Shi-Shun, Li, Jian-Wu & Jin, Xiao-Hua, 2023, New species and record of Gastrochilus (Orchidaceae, Aeridinae) from China and Laos, pp. 210-224 in Phytotaxa 585 (3) on page 218, DOI: 10.11646/phytotaxa.585.3.3, http://zenodo.org/record/769080
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