Poly[diaqua­(μ2-5-carboxy­pyridine-3-carboxyl­ato-κ2 N:O 3)hemi(μ2-oxalato-κ4 O 1,O 2:O 1′,O 2′)(μ4-pyridine-3,5-dicarboxyl­ato-κ4 N:O 3:O 3′:O 5)silver(I)terbium(III)]

In the title coordination polymer, [AgTb(C7H3NO4)(C7H4NO4)(C2O4)0.5(H2O)2]n, the TbIII ion is eight-coordinated by three O atoms from three different pydc (H2pydc = pyridine-3,5-dicarboxylic acid) ligands, one O atom from one Hpydc ligand, two O atoms from one oxalate ligand and two water mol­ecules in a distorted square-anti­prismatic geometry. The AgI ion is coordinated in an almost linear fashion by two pyridyl N atoms from one pydc and one Hpydc ligand and has weak inter­actions with two carboxyl­ate O atoms. The carboxyl­ate groups of pydc and Hpydc ligands link Tb centers, forming a one-dimensional chain. The oxalate adopts a tetra­dentate bis-chelating coordination mode, connecting the chains into a two-dimensional layer. These layers are further assembled via [Ag(pydc)(Hpydc)] pillars and O—H⋯O and C—H⋯O hydrogen bonds into a three-dimensional coordination framework

Studies on the soybean aphid, Aphid glycines Matsumura

The soybean aphid is widely distributed among all major soybean growing regions in China. It causes severe damage in Jilin, Liaoning, and Helongjiang Provinces, and part of the inner Mongolian autonomous region, and those areas are often called aphid-stricken areas. Its hosts include wild soybean (Glycine benth forma lanceolate Makino), buckthorn (Rhamnus davuricus) as well as soybean. Results of field investigation and inoculation experiments confirmed that the widely distributed buckthorn in the Northern Provinces is the over-wintering host for soybean aphids. According to the life cycle of aphids and their characteristic damage to soybeans, three different periods of impact can be recognized: 1) starting from seedling stage to blooming stage (mid-July), the aphid population reaches its peak point. About 50-70% of the whole aphid population colonizes on the tender leaves and twigs on top of the soy plants. The soybean damage caused during this period has the worst impact on the plants. 2) During the third ten days of July when the soybean plants cease to grow, aphids then migrate from the top leaves and twigs to the middle or lower ones and feed on the underside of the leaves. At the same time, the young nymphs appear. The aphid population grows slowly, and their damage to soybean plants is at a low tide. 3) From late August -- the late pod bearing period -- to early September -- the yellow maturing period -- aphids start their late multiplying stage. In late Fall, aphids migrate back to buckthorn, their overwintering host, and oviposit overwintering eggs after mating. During Fall, the male aphids and the ovipositional female aphids are living on different hosts. Gynoparae live on buckthorn, and the male aphids live on soybean. Aphids reproduce 15 generations a year on soybean. After analyzing the life cycle of aphids, their growth pattern in the field, as well as the meteorological data in recent years, we came to preliminary results about the growth and decline pattern of aphids and their affecting factors: 1) the more the overwintering eggs and aphids numbers were at the seedling stage, the more severe their impact on seedlings; 2) Average temperatures between 22-25 °C and relative humidity below 78% from late June to early July greatly favored the growth and reproduction of aphids. Even if the original aphid population is small, severe aphid epidemics still could occur during the blooming period in July because aphids reproduced very quickly under those favorable weather conditions; 3) As the growth points ceased growing in late July and the nutrient condition deteriorated, the aphid population declined. In summary, we may make long- or short-term predictions of aphid epidemics based on the number of overwintering eggs, meteorological data, and current and past aphid information. Based on the results of several years’ laboratory and field experiments, the following aphid control measures achieved very good results: 0.5% lindane (benzene hexachloride, or BHC), 1 to 300-400 diluted 6% BHC wettable powder, 1 to 15000 diluted E605 (parathion), 1 to 100 diluted tobacco leaf solution, and seed coating with 20% BHC. Among these methods, 0.5% BHC powder and seed coating with 0.7% of 20% BHC have been widely used in agricultural practice.Originating text in Chinese.Citation: Wang, Cheng Lun, Xiang, Liang Ying, Zhang, Guang Xue, Zhu, Hong Fu. (1962). Studies on the soybean aphid, Aphid glycines Matsumura. Acta Entomologica Sinica, 11, 31-44

Site-selective doublon-holon dynamics in a pumped one-dimensional Hubbard superlattice with staggered Coulomb interactions

Doublon-holon dynamics is investigated in a pumped one-dimensional Hubbard model with a staggered on?site Coulomb interaction at half-filling. When the system parameters are set to be in the Mott insulating regime the equilibrium sublattice density of states exhibits several characteristic peaks, corresponding to the lower and upper Hubbard bands as well as hybridization bands. We study the linear absorption spectrum and find two main peaks characterizing the photon frequencies which excite the ground state to an excited state. For a system driven by a laser pulse with general intensity and frequency, both the energy absorption and the doublon-holon dynamics exhibit distinct behaviors as a function of laser amplitude and frequency. Single-photon processes are observed at low laser intensity where the energy is absorbed for resonance laser frequencies. For strong laser intensity multi-photon induced dynamics are observed in the system, which are confirmed by an evaluation of the Loschmidt amplitude. The contribution of multi-photon processes to site-specific double occupancy is also characterized by the generalized Loschmidt amplitude. The site-selective doublon-holon dynamics are observed in both the one and multi-photon processes and the site-selective behavior is explained within a quasiparticle picture. Our study suggests strategies to optically engineer the doublon-holon dynamics in one dimensional strongly correlated many-body systems.Comment: 10 pages, 7 figure

Linking nutrient strategies with plant size along a grazing gradient: Evidence from Leymus chinensis in a natural pasture

AbstractStudying the changes in nutrient use strategies induced by grazing can provide insight into the process of grassland degradation and is important for improving grassland quality and enhancing ecosystem function. Dominant species in meadow steppe can optimize their use of limiting resources; however, the regulation of nutrient use strategies across grazing gradients is not fully understood. Therefore, in this study, we report an in situ study in which the impact of grazing rates on nutrient use strategies of Leymus chinensis, the dominant plant species in eastern Eurasian temperate steppes, was investigated. We conducted a large randomized controlled experiment (conducted continuously for five years in grassland plots in a natural pasture in Hailar, eastern Mongolia Plateau, China) to assess the effects of grazing rate treatments (0.00, 0.23, 0.34, 0.46, 0.69, and 0.92 adult cattle unit (AU) ha−1) on L. chinensis along a grazing gradient and employed a random sampling approach to compare the accumulation, allocation, and stoichiometry of C, N, and P in leaves and stems. Our findings demonstrated the follows: (i) The height of L. chinensis decreased with an increase in the grazing gradient, and the concentrations of C, N, and P significantly increased; (ii) the accumulation of C, N, and P per individual was negatively correlated with the concentration of aboveground tissues, suggesting that there was a tradeoff in L. chinensis between nutrient accumulation and concentration at the individual scale; (iii) the leaf-to-stem ratio of C, N, and P accumulation increased with grazing intensity, indicating a tradeoff in nutrient allocation and plant size at the individual plant level; and (iv) grazing rates were negatively correlated with the ratios of C:N and C:P in the stem; however, these ratios in leaves significantly increased with grazing intensity. Our findings suggest that L. chinensis in meadow steppe adapts to grazing disturbance through tradeoffs between plant size and nutrient use strategies. Moreover, our results imply that grazing produces a compensatory effect on nutrient use efficiency between the stems and leaves of L. chinensis