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We demonstrate a high-speed 8.5 μm quantum cascade laser with room temperature continuous wave operation. The maximum output power of 141 mW is obtained at 20 ℃. The parasitic capacitance of the device is decreased from 36.6 pF to 7.1 pF by monolithic integrating a π-shape metal contact electrode. This results in an increase in the -3 dB RF modulation bandwidth from 870 MHz to 4.5 GHz compared with the conventional electrode configuration.

The ecological consequences of precipitation change and increased atmospheric nitrogen (N) deposition have profound impacts on ecosystem CO2 exchange in grassland ecosystems. Water and N can largely influence grassland productivity, community composition and ecosystem functions. However, the influences of water and N addition on the ecosystem CO2 exchange of alpine grassland ecosystems remain unclear. A field manipulative experiment with water and N additions was conducted in an alpine meadow on the Tibetan Plateau over 4 years with contrasting precipitation patterns. There were four treatments: control (Ctrl), N addition (N), water addition (W) and N and water addition (NW), each replicated three times. N addition, but not water addition, increased gross ecosystem productivity (GEP), plant biomass, community cover and community-weighted mean height. The responses of ecosystem CO2 exchange to water and N addition varied between the wet and dry years. Water addition had a positive effect on net ecosystem carbon exchange (NEE) due to a larger increase in GEP than in ecosystem respiration (ER) only in the dry year. On the contrary, N addition significantly enhanced ecosystem CO2 exchange only in the wet year. The increased GEP in N addition was attributed to the larger increase in NEE than ER. Moreover, N addition stimulated NEE mainly through increasing the cover of dominant species. Our observations highlight the important roles of precipitation and dominant species in regulating ecosystem CO2 exchange response to global environmental change in alpine grasslands.

In this study, we compareWestern oil paintings and Chinese ink paintings on their composition, by extracting and computing 28 composition features of the paintings, including visual balance and relationships between different regions (segments). Among the extracted segments, we compute average distance and rule-based features based on three layout rules, rule of thirds, golden mean and golden triangle.Atotal of 2253 paintings including 1138 oil paintings and 1115 Chinese ink paintings are collected. By comparing the results of the features on these paintings, our study investigates the difference and similarity between the two types of paintings on composition. Their composition designs are similar in visual balance and their tendency of composing along two diagonal lines, but are fairly different on many other aspects. For example, oil paintings are inclined to place objects on the bottom horizontal dividing lines of rule of thirds and golden mean. Having discovered the most important features that can differentiate the two types of paintings, we analyze the differences in the features and discuss their possible relationships to the culture and artists’ backgrounds.

The interaction between an ultrastrong laser and a cone-like target is an efficient approach to generate high power radiations like attosecond pulses and terahertz waves. The object is to study the $\gamma$-ray generation under this configuration with the help of 2D particle-in-cell simulations. It is deciphered that electrons experience three stages including injection, acceleration and scattering to emit high energy photons via nonlinear compton scattering (NCS). These spatial-separated attosecond $\gamma$-ray pulses own high peak brilliance ($>10^{22}$ photons/($\rm s\cdot\rm mm^2\cdot\rm mrad^2\cdot0.1\%BW$)) and high energy (6MeV) under the case of normalized laser intensity $a_0=30$ ($\mathrm{I=2\times10^{21}W/cm^2}$). Besides, the cone target turns out to be an order of magnitude more efficient in energy transfer compared with a planar one., Comment: 14 pages, 6 figures

The genus Lonicera (Caprifoliaceae) is of great economical significance. It has been taxonomically studied frequently in history, while phylogenetic relationships intra the genus are still obscure. Here, we reported the first species complete chloroplast genome sequence in the section Isoxylosteum, Lonicera angustifolia var. myrtillus. It is 156,222 bp in length, comprising a large single-copy (LSC) region of 89,838 bp, a small single-copy (SSC) region of 19,211 bp, and a pair of inverted repeats (IRs) of 23,509 bp. In L. angustifolia var. myrtillus chloroplast genome, a total of 114 functional genes were identified, with an overall GC content of 38.4%. The phylogenetic relationships of Lonicera based on maximum-likelihood (ML) showed that L. angustifolia var. myrtillus is most closely related to L. nervosa in section Isika. Our study contributes to the molecular phylogenetic studies of Lonicera and Caprifoliaceae.

We demonstrate InP-based buried grating coupled surface-emitting distributed feedback (DFB) lasers designed to operate at a wavelength of 2004 nm. The laser structure consists of three InGaAsSb/InGaAs QWs, with a 5 $\mu \text{m}$ wide double-channel ridge waveguide. A second-order semiconductor/semiconductor grating is used for in-plane feedback and vertical out-coupling. The single longitudinal mode emission wavelength of the fabricated laser can be adjusted from 2002.7 to 2006 nm without any mode hopping. High side-mode suppression ratio (SMSR) of at least 35 dB is achieved under all injection currents and temperature conditions. The edge output power reaches 19 mW, measured in continuous-wave (CW) mode at 10 °C. Simultaneously, the output power of surface emission reaches 8 mW.

We report a very long wave (14 μm) infrared quantum cascade detector based on a twin-well coupled absorption region operating at temperatures up to 130 K. By introducing two coupled absorption quantum wells that have the same width, the absorption strength and responsivity of the detector are increased relative to the single-well design. At 77 K, we observe a responsivity of 4.06 mA/W at zero bias, which is 4.27 times that of the single-well counterpart. The responsivity is further optimized for reverse bias operation, so that the obstruction of space charge field to electron transport is compensated. The photocurrent reaches a maximum value at 77 K for an applied bias of −1.3 V, and responsivity as high as 23.76 mA/W, which is 5.85 times that under zero bias, is obtained.

Physochlaina is an important perennial herbaceous genus with significant medicinal value, while the phylogeny of Physochlaina and tribe Hyoscyameae is not well resolved yet. In this study, we report the complete chloroplast genome sequences of Ph. physaloides, its complete chloroplast genome is 156,413 bp in length, which is a typical quadripartite structure that includes a large single-copy region of 86,659 bp, a small single-copy region of 18,012 bp, and its GC content was 37.7%. A total of 132 genes were identified, including 87 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Furthermore, a phylogenetic tree of the tribe Hyoscyameae was constructed based the complete chloroplast genome sequence, and a new topology of the tribe was obtained. This study provides valuable genetic information for the conservation and utilization of Ph. physaloides and also provide the potential for better understanding of the phylogeny of Hyoscyameae and Solanaceae.

The walnut family Juglandaceae was widely distributed in the Northern Hemisphere while several extant genera now exhibit intercontinental disjunctions. Recent progress in the systematics of Juglandaceae has greatly broadened our knowledge about its origin and evolution. However, there are still uncertainties about the intergeneric relationships within Juglandaceae, and discrepancies between fossil records and inferred divergence times for certain lineages were observed. In this study, well-resolved phylogenies of the Juglandaceae are reconstructed based on both the nuclear RAD-Seq and the whole chloroplast genome data. Our results support the Juglandoideae topology of (Hicoreae, (Platycaryeae, Juglandeae)) at the tribal level. Within Juglandeae, a discordant position of Pterocarya was detected between nuclear and plastid genome data, and a more likely topology (nuclear), (Juglans, (Pterocarya, Cyclocarya)), was discussed based on evidence from molecular data and fossil records. Based on carefully selected fossil calibrations, the divergence times of extant lineages were estimated and they corroborated well with fossil records (especially concerning Juglans and Pterocarya). Four sections within Juglans were strongly supported by the nuclear data. Within Juglans, the incongruent position of J. hopeiensis was recovered between the nuclear and plastid genomes. Yet the origin and evolutionary history of J. cinerea and J. hopeiensis are supported to be complicated and need further clarification. Integrative evidence from the fossil records, phylogeny and lineage divergence times shows that Juglandoideae originated in North America, and migrated to Eurasia via both the Bering and the North Atlantic land bridges. Our study shows the potential of integrative biogeographic studies for illuminating the evolutionary history of Juglandaceae.

We demonstrate a quantum cascade detector with two coupled double-well structures exhibiting a high peak responsivity of 166 mA W−1 for 8.2 μm detection at 80 K. The coupled double-absorption-well design offers enhanced absorption efficiency. Meanwhile, incorporating another coupled double-well structure in the extractor increases the extraction efficiency. Both factors contribute to the high performance of our device.

Three new lanthanide-nitronyl nitroxide radical complexes [Ln(tfac)3(NIT-2thz)] (Ln(III) = Gd 1, Tb 2, Dy 3; tfac = trifluoroacetylacetonate; NIT-2thz = 2-(2′-thiazolyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) have been synthesized. Single crystal X-ray diffraction analyses reveal that complexes 1–3 are isomorphous. They all crystallized in the C2/c space groups. Each central Ln(III) ion is eight-coordinated by three bischelate tfac ligands and one radical ligand. More specifically, NIT-2thz acts as a chelate ligand to link one Ln(III) ion through its nitrogen atom of the thiazole ring and oxygen atom of the N–O group to form a two-spin system. Magnetic studies show that Gd complex exhibits ferromagnetic Gd(III)–radical coupling, Tb and Dy complexes exhibit frequency-dependent out-of-phase signals.

We have demonstrated a mid-wave/long-wave dual-color infrared quantum cascade detector enhanced by antenna-coupled microcavity. By optimizing the size of patches, the coupling wavelength of the antenna-coupled microcavity can be conveniently tuned to match the targeted intersubband transition energy. At 77 K, the peak responsivity of our detector is 4.1 mA/W for long wave (10.4 µm) and 0.6 mA/W for mid wave (5.8 µm), while the detectivity is 1.8×109 cm·Hz1/2/W (Jones) and 2.6×108 cm·Hz1/2/W (Jones), respectively. Compared with a reference device with a 45° multi-pass geometry, the responsivity of our detector has been increased by a factor of 9.1 for the long wave and 2.7 for the mid wave. Our results illustrate how to realize a dual-color infrared detector and improve the optoelectronic performance through the concept of antenna-coupled microcavity.

We demonstrate a long-wavelength infrared quantum cascade detector (QCD) that operates at a wavelength of 10 μm, in which the active diagonal transition for the electrons occurs from a fundamental energy level into a miniband in adjacent coupled quantum wells. When compared with a bound-to-bound diagonal transition-based QCD, the use of a miniband as the final transition state increases the absorption strength and enhances the electron extraction efficiency of the device, leading to QCD responsivities of 75 at 180 and 30 mA/W at 300 K for 10.55 μm wavelength operation.

Near-infrared (NIR) luminescence detection of picric acid (PA) was achieved sensitively and selectively by using a nanosized Nd-III metal-organic cage (MOC) for the first time.

Species in the genus Botrychium are tiny herbaceous plants with simple morphology that are widely distributed in the northern hemisphere. The phylogenetic relationship intra the genus is not well r...

The study evaluated GIMMS NDVI based on MODIS NDVI and SPOT NDVI over the same period from 2000 to 2015. We assessed their absolute values, dynamics, trends and cross-relationships between any two of the NDVIs for the national scale, as well as four separate land use types, i.e., paddy field, dry land, forest, and grassland. GIMMS NDVI was numerically greater than MODIS NDVI and SPOT NDVI. The three NDVIs exhibited equal capability of capturing monthly phenological variations. During the study period, the three NDVIs showed increasing trends in most regions, with GIMMS NDVI showing the smallest increment. Pronounced differences were identified in trends between GIMMS NDVI and MODIS NDVI or SPOT NDVI in the northwest, northeast, south-central China, Tibetan Plateau and Yunnan-Guizhou Plateau, implying that GIMMS NDVI trends in these regions should be interpreted with caution. High correlations existed between the three datasets. MODIS NDVI and SPOT NDVI showed stronger correlations at national scale. The GIMMS NDVI and MODIS NDVI were in highest accordance for dry land, while MODIS NDVI and SPOT NDVI were in higher accordance for the paddy field, forest, and grassland than dry lands.以MODIS NDVI和SPOT NDVI数据为基准对2000—2015年重叠时段的GIMMS NDVI数据进行评价.在全国尺度以及水田、旱地、林地、草地4种土地类型上对比分析3种数据的数值差异、动态一致性、变化趋势差异和两两间相关性.结果表明: GIMMS NDVI在数值上整体高于MODIS NDVI和SPOT NDVI,3种数据在反映植被月动态方面能力相当;研究期内3种NDVI数据在全国大部分区域均呈增加趋势,GIMMS的增加幅度最小,且在我国西北、东北、中南、青藏高原及云贵高原的部分地区与另两套数据差异较大,表明在研究该区域时应对GIMMS NDVI数据的使用有所保留;各数据间两两相关性较强,在全国尺度上MODIS NDVI与SPOT NDVI的相关性更好,旱地GIMMS NDVI与MODIS NDVI的相关性更好,水田、林地、草地MODIS NDVI与SPOT NDVI的相关性更好.

A tetrapodal zwitterionic-type ligand featuring both AIE (aggregation-induced emission) and ILCT (intraligand charge transfer) properties, namely 1,1',1'',1'''-(4,4',4'',4'''-(ethene-1,1,2,2-tetrayl)tetrakis(benzene-4,1-diyl))tetrakis(methylene)tetrapyridin-4(1H)-one (TPE-4PO) has been designed and applied to the assembly of lanthanide complexes LIFM-21(Ln) (Ln = Sm, Eu, Gd, Tb and Dy). Apart from sensitization of NIR emission of Sm(3+) and Dy(3+), the resulting ligand and lanthanide complexes show both AIE and ILCT-related photoluminescence behaviors. The photo-response of this system to different aggregation states, solvents' polarity and mechanical grinding was demonstrated by distinguishable emission intensities and colours.

Physochlaina is an important perennial herbaceous genus with significant medicinal value, while the phylogeny of Physochlaina and tribe Hyoscyameae is not well resolved yet. In this study, we report the complete chloroplast genome sequences of Ph. physaloides, its complete chloroplast genome is 156,413 bp in length, which is a typical quadripartite structure that includes a large single-copy region of 86,659 bp, a small single-copy region of 18,012 bp, and its GC content was 37.7%. A total of 132 genes were identified, including 87 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Furthermore, a phylogenetic tree of the tribe Hyoscyameae was constructed based the complete chloroplast genome sequence, and a new topology of the tribe was obtained. This study provides valuable genetic information for the conservation and utilization of Ph. physaloides and also provide the potential for better understanding of the phylogeny of Hyoscyameae and Solanaceae.

Lonicera oblata, a critically endangered species endemic to North China with about 30 wild individuals, has long been ignored for conservation since its publication because of little attention on its living situation. In this study, we characterized the complete chloroplast (cp) genome of L. oblata. The cp genome was 155,481 bp in length, included a large single-copy (LSC) region of 89,139 bp, a small single-copy (SSC) region of 18,676 bp, and two inverted repeat (IR) regions of 23,833 bp each. The genome contains 130 genes, including 85 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Phylogenetic position of L. oblata was also investigated based on cp genome phylogeny of Lonicera representatives. This study is valuable for molecular phylogenetic study and conservation of Lonicera and related taxa.

The coordination of a rigid triangular ligand 2,4,6-tris[4-(1H-imidazole-1-yl)phenyl]-1,3,5-triazine (TIPT) with Cd(II) ions afforded two compounds with structural motifs of a CdI2-type and a (4,4) network for anions OTf− (CF3SO3−) and OTs− (p-CH3C6H5SO3−), respectively, between which structural transition can be induced by anion exchange via solvent-mediated recrystallization process. Using this method, a pure substance can be obtained from a mixture under the excess of certain kind of anions.

The coordination of metal ions with a pair of chiral tripodal ligands (R or S)-2-(2-((bis(pyridin-2-ylmethyl)amino)methyl)phenoxy)-N-(1-phenylethyl)acetamide (R- or S-L) results in the circular dichroism (CD) enhancement distinctly, giving fingerprint information among different metals. Specifically, the CD signals show more obvious magnification upon coordination with Ln3 + compared with Zn2 + and other metals. Structural analyses show that in Eu-complex (1), the Eu3 + metal center is surrounded in a 10-coordinating geometry and the ligand takes fan-like configuration, while in Zn-complex (2), Zn2 + is surrounded in a 7-coordinating geometry and the ligand takes pincer-like configuration. These differences in the coordination structure as well as intramolecular packing effects are responsible for the variation in CD signal responses of different metal-coordinated systems.

Two series of Pb(II)–Ln(III) heteronuclear coordination complexes are assembled from a tripodal ligand triCB-NTB ((4,4′,4′′-(2,2′,2′′-nitrilotris(methylene)tris(1H-benzo[d]imidazole-2,1-diyl)tris(methylene))tribenzoic acid)). In the Pb2LnL2 series, the Ln3+ ion is encapsulated in a highly symmetrical {LnO6} octahedron with an inversion center, and Pb–Ln–Pb clusters are formed by the linkage of carboxyl groups on triCB-NTB ligands to Pb2+ and Ln3+ simultaneously. However, in the PbLn2L2 series, the Ln3+ ion is encapsulated in a distorted {LnO9} polyhedron without an inversion center. Pb2+ ions are coordinated with benzimidazole and apical N atoms on the ligand in isolation, and the carboxyl groups link two Ln3+ ions into a Ln–Ln cluster. This structural variation leads to different photoluminescence behaviour in these two series of complexes. Most importantly, the linkage of the Pb–Ln–Pb clusters causes more perturbation to the excited states of the ligand. Therefore, a more obvious ligand-to-metal charge transfer (LMCT) process is observed in the Pb2LnL2 series, and the energy transfer to the accepting levels of Ln3+ ions becomes more efficient. Furthermore, the combination of LC (ligand-centered) + LMCT + MC (metal-centered) emissions in the Pb2EuL2 complex results in single component white light emission.

Core–shell or striped heteroatomic lanthanide metal–organic framework hierarchical single crystals were obtained by liquid-phase anisotropic epitaxial growth, maintaining identical periodic organization while simultaneously exhibiting spatially segregated structure. Different types of domain and orientation-controlled multicolor photophysical models are presented, which show either visually distinguishable or visible/near infrared (NIR) emissive colors. This provides a new bottom-up strategy toward the design of hierarchical molecular systems, offering high-throughput and multiplexed luminescence color tunability and readability. The unique capability of combining spectroscopic coding with 3D (three-dimensional) microscale spatial coding is established, providing potential applications in anti-counterfeiting, color barcoding, and other types of integrated and miniaturized optoelectronic materials and devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel dynamic covalent gel has been prepared via the imine bond formation reaction of tetraamine building blocks with luminescent tetraphenylethene tetraaldehyde units. The gel shows high hierarchical porosity (SBET = 512 m(2) g(-1)) and remarkable aggregation-induced emission enhancement, which has been demonstrated to be a selective sensor.

Because of rapid diversification and frequent interspecific gene flow within the genus and inappropriate molecular markers used for phylogenetic studies, phylogeny and evolution of the economically significant crop genus Vitis are poorly resolved and understood, and species delimitation of Vitis remain disputable. In order to better understand of relationships within Vitis, phylogenomic analysis of chloroplast genomes were performed based on extensive sampling scheme. Well resolved phylogenetic tree and clear divergence pattern of Vitis were obtained in the present study. The results shows that subg. Vitis was constituted by three strongly supported monophyletic clades whose species are distributed in North America, Europe and Asia, respectively. Nine molecular markers are provided as potential markers for DNA barcoding and phylogenetic study of Vitis. Furthermore, taxonomic position of the critically endangered species endemic to Northern China, V. baihuashanensis, is investigated and suggested to be a separate species based on phylogenomic analysis and morphological comparisons, and effective conservation actions is badly needed. Molecular resources reported in this study could also be used for genetic engineering studies of Vitis, and will potentially promote genomic exploration of crop wild relatives and conservation of the germplasm.

Two zwitterionic-type ligands featuring π-π* and intraligand charge-transfer (ILCT) excited states, namely 1,1'-(2,3,5,6-tetramethyl-1,4-phenylene)bis(methylene)dipyridinium-4-olate (TMPBPO) and 1-dodecylpyridin-4(1 H)-one (DOPO), have been prepared and applied to the assembly of lanthanide coordination complexes in an effort to understand the ligand-direction effect on the structure of the Ln complexes and the ligand sensitization effect on the luminescence of the Ln complexes. Due to the wide-band triplet states plus additional ILCT excitation states extending into lower energy levels, broadly and strongly sensitized photoluminescence of f→f transitions from various Ln(3+) ions were observed to cover the visible to near-infrared (NIR) regions. Among which, the Pr, Sm, Dy, and Tm complexes simultaneously display both strong visible and NIR emissions. Based on the isostructural feature of the Ln complexes, color tuning and single-component white light was achieved by preparation of solid solutions of the ternary systems Gd-Eu-Tb (for TMPBPO) and La-Eu-Tb and La-Dy-Sm (for DOPO). Moreover, the visible and NIR luminescence lifetimes of the Ln complexes with the TMPBPO ligand were investigated from 77 to 298 K, revealing a strong temperature dependence of the Tm(3+) ((3) H4 ) and Yb(3+) ((2) F5/2 ) decay dynamics, which has not been explored before for their coordination complexes.

A new type of ILCT ligand was designed to sensitize both visible and NIR emission of a Pr3+complex, and tunable single component white light and a dual-channel barcode module was achieved in Pr(iii)-MOFs for the first time.

Four Ru(II)/Ir(III) metalloligands have been designed and synthesized from polypyridine and bibenzimidazole (BiBzIm) organic ligands, which show strong visible light absorption via metal-to-ligand charge transfer (MLCT) transitions. Nd/Yb(III) complexes were further assembled from these Ru(II)/Ir(III) metalloligands, and Ln(III)-centered NIR emissions can be efficiently sensitized by (3)MLCT states of the metalloligands in the visible-light region. The energy transfer rates for the complexes are generally in the order NdYb, which is due to the better matching between (3)MLCT states of Ru(II)/Ir(III) metalloligands and densely distributed excited states of Nd(III) ions. Long decayed lifetimes on a μs scale and high quantum yields up to 1% are obtained in these lanthanide complexes, suggesting that the Ru(II)/Ir(III) metalloligands can serve as a good visible light harvesting antenna to efficiently sensitize Ln(III)-based NIR luminescence.

Holopogon pekinensis, a new heteromycotrophic orchid from Beijing City, China, is described and illustrated. This new species is morphologically similar to an endangered species endemic to Far East Russia, Holopogon ussuriensis Komarov & Nevski, but differs in having green flowers (vs white) and light green pubescence (vs red). Its conservation status and an identification key to Holopogon are provided.

A tetraphenylethylene-based phosphine, 1,1,2,2-tetrakis((4-diphenylphosphino)phenyl)ethylene (TPE-P4), was synthesized and showed novel aggregation-induced and mechano-responsive emission. A mixture of TPE-P4 and Ag(+) could fix atmospheric CO2in situ as carbonate ions in neutral solution to yield a rare 3D metal-organic framework with zeolite-like SOD topology, [Ag2(TPE-P4)CO3]x⊃nH2O (Ag-TPE-P4). Ag-TPE-P4 showed turn-on luminescence of TPE-P4, emitting bright bluish green light in the solid state.

To develop luminescent gels, a series of metal–organic gels have been successfully synthesised based on trivalent metal ions (Al3+, Cr3+, Fe3+, Ga3+, and In3+) and tetrakis(4-carboxyphenyl)ethylene (H4TCPE) that has aggregation-induced emission (AIE) features. Among these gels, the Al-TCPE gel has both high hierarchical micro- and mesoporosity and AIE effect. The Al-TCPE aerogel consists of metal–organic framework nanocomponents as revealed by TEM and PXRD, which contribute to its high microporosity. Using tetraphenylethylene as a building block endows the Al-TCPE gel with AIE photoluminescence. The Al-TCPE gel shows potential in the selective detection of explosives with picric acid chosen as a model explosive.