38,315 research outputs found
Evidence for erbium-erbium energy migration in erbium(III) bis(perfluoro-p-tolyl)phosphinate
No full textCopyright 2008 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Applied Physics Letters 92, 103303 (2008) and may be found at
Physical origin of Davydov splitting and resonant Raman spectroscopy of Davydov components in multilayer MoTe2
No full textWe systematically study the high-resolution and polarized Raman spectra of multilayer (ML) MoTe2. The layer-breathing (LB) and shear (C) modes are observed in the ultralow-frequency region, which are used to quantitatively evaluate the interlayer coupling in ML MoTe2 based on the linear chain model, in which only the nearest interlayer coupling is considered. The Raman spectra on three different substrates verify the negligible substrate effect on the phonon frequencies of ML MoTe2. Ten excitation energies are used to measure the high-frequency modes of N-layer MoTe2 (NL MoTe2; N is an integer). Under the resonant excitation condition, we observe N-dependent Davydov components in ML MoTe2, originating from the Raman-active A(1)' (A(1g)(2)) modes at similar to 172 cm(-1). More than two Davydov components are observed in NL MoTe2 for N > 4 by Raman spectroscopy. The N-dependent Davydov components are further investigated based on the symmetry analysis. A van der Waals model only considering the nearest interlayer coupling has been proposed to well understand the Davydov splitting of high-frequency A(1)' (A(1g)(2)) modes. The different resonant profiles for the two Davydov components in 3L MoTe2 indicate that proper excitation energy of similar to 1.8 - 2.2 eV must be chosen to observe the Davydov splitting in ML MoTe2. Our work presents a simple way to identify layer number of ultrathin MoTe2 flakes by the corresponding number and peak position of Davydov components. Our work also provides a direct evidence from Raman spectroscopy of how the nearest van der Waals interactions significantly affect the frequency of the high-frequency intralayer phonon modes in multilayer MoTe2 and expands the understanding on the lattice vibrations and interlayer coupling of transition metal dichalcogenides and other two-dimensional materials.National Basic Research Program of China [2013CB921901, 2012CB932703]; National Natural Science Foundation of China [11225421, 11434010, 11474277, 61125402, 51172004, 11474007]SCI(E)[email protected]; [email protected]
Electroweak corrections to the decay H+ -> W(+)h in the minimal supersymmetric model
No full textWe calculate the O(alpha (ew)m(t(b))(2)/m(W)(2)) and O(alpha (ew)m(t(b))(4)/m(W)(4)) supersymmetric electroweak corrections to the process H+ --> W(+)h in the Minimal Supersymmetric Model. These corrections arise from the virtual effects of the third family quarks (top and bottom) and squarks (top-squark and bottom-squark). We find that for m(H+) > 200 GeV at low tan beta(less than or equal to 3), the corrections can increase the tree-level decay widths and the branching radios more than 20% and 40%, respectively. (C) 2001 Elsevier Science B.V. All rights reserved.Physics, MultidisciplinarySCI(E)4ARTICLE1-2101-11049
Figure 1 from: Yang B, Zhou S-S, Ding H-B, Li R, Maung KW, Tan Y-H (2018) Two new species of Trivalvaria (Annonaceae) from northern Myanmar. In: Jin X-H, Shui Y-M, Tan Y-H, Kang M (Eds) Plant diversity in Southeast Asia. PhytoKeys 94: 3-12. https://doi.org/10.3897/phytokeys.94.21553
No full textFigure 1 Trivalvaria rubra Y.H.Tan, S.S.Zhou & B.Yang, sp. nov. A Habitat B Branch with flowers (adaxial view) C Branch with flowers (abaxial view) D Male flower (abaxial view) E Flower bud (side view) F Female flower (abaxial view) G Flower (G1 Bracts; G2 Sepals; G3 Outer petals; G4 Inner petals; G5 Androphore) H Fruit. Photographed by Y.H. Tan, H.B. Ding and B. Yang
L(h,1,1)-Labeling of Outerplanar Graphs
No full textAn -labeling of a graph is an assignment of labels from the set of integers
to the vertices of the graph such that adjacent
vertices are assigned integers of at least distance apart
and all vertices of distance three or less must be assigned different labels.
%%(except for , where adjacent nodes may have the same label).
The aim of the -labeling problem is to minimize ,
denoted by and called \emph{span} of the -labeling.
As outerplanar graphs have bounded treewidth, the -labeling problem on outerplanar graphs can be exactly solved in , but the multiplicative factor depends on the maximum degree and is too big to be of practical use. %where the multiplicative constant is exponential in their maximum degree .
In this paper we give a linear time approximation algorithm for computing the more general -labeling for outerplanar graphs that is within additive constants of the optimum values
Figure 4 from: Ding H-B, Maw MB, Yang B, Bouamanivong S, Tan Y-H (2020) An updated checklist of Begonia (Begoniaceae) in Laos, with two new species and five new records. In: Jin X-H, Xia N-H, Tan Y-H (Eds) Plant diversity of Southeast Asia-II. PhytoKeys 138: 187-201. https://doi.org/10.3897/phytokeys.138.46718
No full textFigure 4 A–CBegonia lancangensis S.H. Huang: A habitat B staminate flower (front view) C staminate flower (back view) D–FBegonia sizemoreae Kiew: D habitat E staminate flower F pistillate flower G–IBegonia silletensis (A. DC.) C.B. Clarke subsp. mengyangensis M.C. Tebbitt & K.-Y. Guan: G habitat H inflorescence I staminate flower (front view). Photographed by H.B. Ding and Y.H. Tan
L(h, 1, 1)-labeling of outerplanar graphs
No full textAn L(h, 1, 1)-labeling of a graph is an assignment of labels from the set of integers {0, . . . , lambda} to the nodes of the graph such that adjacent nodes are assigned integers of at least distance h a parts per thousand yen 1 apart and all nodes of distance three or less must be assigned different labels. The aim of the L(h, 1, 1)-labeling problem is to minimize lambda, denoted by lambda (h, 1, 1) and called span of the L(h, 1, 1)-labeling. As outerplanar graphs have bounded treewidth, the L(1, 1, 1)-labeling problem on outerplanar graphs can be exactly solved in O(n (3)), but the multiplicative factor depends on the maximum degree Delta and is too big to be of practical use. In this paper we give a linear time approximation algorithm for computing the more general L(h, 1, 1)-labeling for outerplanar graphs that is within additive constants of the optimum values
Micrornebius mandai Tan, new species
No full textMicrornebius mandai Tan, new species (Fig. 3) Material examined. Holotype (male): Singapore, near Central Catchment Nature Reserve, near Mandai Lake Road, old secondary swamp forest, on tree bark, coll. M. K. Tan & H. Yeo, 1 June 2014 (ZRC.ORT. 1042, dry pinned). Paratypes: 7 males, 1 female: Singapore, near Central Catchment Nature Reserve: 1 female (ZRC.ORT. 1043 dry pinned), near Mandai Lake Road, old secondary swamp forest, on tree bark, coll. M. K. Tan & H. Yeo, 1 June 2014; 2 males (ZRC.ORT. 1083, ZRC.ORT. 1084, both dry pinned), near Mandai Track 15, disturbed and young secondary forest, on tree bark, coll. M. K. Tan & H. Yeo, 13 June 2014; 1 male (ZRC.ORT. 1169, in alcohol), near Central Catchment Nature Reserve, near Mandai Lake Road, old secondary swamp forest, on leaf litter, coll. M. K. Tan & H. Yeo, 14 August 2014; 3 males (ZRC.ORT. 1148–1150, in alcohol), near Mandai Track 15, disturbed and young secondary forest, on tree bark, coll. M. K. Tan & H. Yeo, 13 September 2014; 1 male (ZRC.ORT. 1147, in alcohol), near Central Catchment Nature Reserve, near Mandai Track 15, disturbed and young secondary forest, on ground, coll. M. K. Tan & H. Yeo, 13 September 2014. Diagnosis. This species differs from all known Micronebius species by male phallic complex with the presence of two forms of sclerotized apical plates and hyalinous pyriform discs. Similar to Micrornebius lineatus Ingrisch, 2006 from Sabah in male phallic complex with apical plates but differs by the presence of two forms of apical plates (paired plates rectangular with rounded edges, with surface densely granular and the third plate appearing more sclerotized with surface sparsely denticulate); medial valves distinctively sclerotized. Similar to Micrornebius insularis Ingrisch, 2006 from Thailand in medial valves of male phallic complex but differs by the presence of apical plates. Similar to Micrornebius malaya Tan & Nizam, 2013 from Peninsular Malaysia in ovipositor with dorsal and ventral apical valves diverging subapically before converging at apex but differs by dorsal apical valve feebly longer than ventral valve (dorsal apical valve much shorter than ventral valve in M. malaya); also differs from M. malaya by male phallic complex. Description. Habitus typical for the genus (Figs. 3 A, 3 B). Frontal rostrum about 4.4 times (n = 4) broader than scapus. Maxillary palps with apical (fifth) segment elongated triangular, fourth segment mostly cylindrical with apical part slightly widened, third segment cylindrical; apical segment slightly longer than fourth segment, apical and third segments of subequal length (Fig. 3 C). Pronotum in male about 1.6 times (n = 8) longer than wide; with anterior dorsal margin straight and posterior dorsal margin broadly rounded, covering tegmen almost completely. Fore tibia with internal tympanum oval, external tympanum absent. Hind femur about 1.4 times (n = 8) longer than hind tibia; hind tibia 2.0 times (n = 8) longer than hind metatarsus. Male. Last abdominal tergite and epiproct fused to a supra-anal plate; basally transverse, apically setose, apical half with a broad medial lobe, with apical margin truncated or broadly rounded (Figs. 3 D, 3 E). Phallic complex as shown in Figs. 3 F, 3 G; with three large, brown, apical plates of two forms; paired plates rectangular to rhomboid, with surface densely granular; the third plate (appearing more sclerotized), hemi-elliptical (one end with rounded margin and the opposite end with straight margin) with surface sparsely denticulate (Fig. 3 F). Below those plates with two smaller elongated pyriform (teardrop-shaped) discs which are largely hyaline except for external margin (Fig. 3 F). Medial valves distinctively sclerotized; basal plate with two strongly sclerotized processes, between ejaculatory duct with two longitudinal branches connected by a basal plate; branches with basal half widened flattened to form a lamella and gently bent dorsad (when viewed laterally), distal half of branch rod-shaped and apex bent externally (Fig. 3 G). Ejaculatory duct connected to basal plate of medial valves. Female. Supra-anal plate setose, with two white lateral patches, apical margin rounded. Subgenital plate triangular, longer than broad, apical margin feebly emarginated in middle, setose throughout (Fig. 3 H). Ovipositor with dorsal and ventral apical valves diverging subapically before converging at apex; dorsal valve slightly longer than ventral valve; dorsal valve with apex rounded, ventral valve more slender with apex more acute (Fig. 3 I). Colouration. Generally brown when without scales, scales brown and silvery in fresh specimens. Head yellow brown, eyes dark; scapus and basal antennal segments pale yellow brown and partly black; maxillary palps mostly brown, joints between segments a little pale. Pronotum generally yellow brown when naked, with brown and silvery scales (Fig. 3 B). Mesosternum and metasternum pale yellow. Legs, including tarsi, generally pale with few dark brown variegation. Hind femora inner surface mostly naked, pale yellow at base and with brown scales near knees and upper margins; outer surface with brown scales. Hind tibiae black with yellow variegation. Abdominal tergites mostly black when naked with scales brown and silvery; abdominal sternites and subgenital plate brown (Figs. 3 D, 3 E). Cerci pale variegated with little brown scales (Figs. 3 B, 3 D, 3 E). Ovipositor brown. Measurements. See Table 2. Etymology. This species is named after type locality, Mandai; noun in apposition. Life history. This species inhabits tree trunks, often hiding within crevices and beneath tree bark.Published as part of Tan, Ming Kai, 2014, New species of small scaly crickets of genus Micrornebius (Orthoptera: Mogoplistidae; Mogoplistinae) from Singapore, pp. 117-126 in Zootaxa 3895 (1) on pages 122-123, DOI: 10.11646/zootaxa.3895.1.7, http://zenodo.org/record/22619
The interplay among gas, liquid and solid interactions determines the stability of surface nanobubbles
No full textSurface nanobubbles are gaseous domains found at immersed substrates, whose remarkable persistence is still not fully understood. Recently, it has been observed that the formation of nanobubbles is often associated with a local high gas oversaturation at the liquid-solid interface. Tan, An and Ohl have postulated the existence of an effective potential attracting the dissolved gas to the substrate and producing a local oversaturation within 1 nm from it that can stabilize nanobubbles by preventing outgassing in the region where gas flow would be maximum. It is this effective solid-gas potential-which is not the intrinsic, mechanical interaction between solid and gas atoms-its dependence on chemical and physical characteristics of the substrate, gas and liquid, that controls the stability and the other characteristics of surface nanobubbles. Here, we perform free energy atomistic calculations to determine, for the first time, the effective solid-gas interaction that allows us to identify the molecular origin of the stability and other properties of surface nanobubbles. By combining the Tan-An-Ohl model and the present results, we provide a comprehensive theoretical framework allowing, among others, the interpretation of recent unexplained experimental results, such as the stability of surface nanobubbles in degassed liquids, the very high gas concentration in the liquid surrounding nanobubbles, and nanobubble instability in organic solvents with high gas solubility. This journal i
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