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Towards realizing the future quantum internet1,2, a pivotal milestone entails the transition from two-node proof-of-principle experiments conducted in laboratories to comprehensive multi-node set-ups on large scales. Here we report the creation of memory–memory entanglement in a multi-node quantum network over a metropolitan area. We use three independent memory nodes, each of which is equipped with an atomic ensemble quantum memory3 that has telecom conversion, together with a photonic server where detection of a single photon heralds the success of entanglement generation. The memory nodes are maximally separated apart for 12.5 kilometres. We actively stabilize the phase variance owing to fibre links and control lasers. We demonstrate concurrent entanglement generation between any two memory nodes. The memory lifetime is longer than the round-trip communication time. Our work provides a metropolitan-scale testbed for the evaluation and exploration of multi-node quantum network protocols and starts a stage of quantum internet research.A metropolitan-area quantum network based on the generation of pairwise entanglement is formed by three atomic quantum memories connected to a central photonic server. [ABSTRACT FROM AUTHOR]

Efficient and sustainable chemical fixation of CO2 into value-added chemicals is one of the most promising objectives in environmental chemistry. In this work, transition metal acetylacetonate immobilized onto triazolium ionic liquid-modified periodic mesoporous organosilica PMO-IL-M(x) was successfully prepared and investigated as an effective and heterogeneous catalyst in the direct carboxylation of terminal alkynes and CO2 to the desired alkynyl carboxylic acids. It was found that the catalyst PMO-IL-Sn(0.3) exhibited extraordinary catalytic performance in terms of excellent activity, stability, productivity, and excellent yields under mild reaction conditions. Moreover, the catalyst PMO-IL-Sn(0.3) could be easily recovered and reused at least six times without considerable loss in catalytic activity. This work provides a sustainable and efficient synergistic strategy for the chemical fixation of carbon dioxide into valuable alkynyl carboxylic acids. [ABSTRACT FROM AUTHOR]

The tip clearance induces the tip leakage vortex (TLV), which has a great impact on the pressure fluctuation characteristics of the multiphase pump. To investigate the effect of the tip clearance on the pressure fluctuations, based on the Reynolds time-averaged Navier-Stokes equation and the shear stress transfer (SST) k - ω turbulence model, the three-dimensional turbulent flow in the pump is numerically simulated for different tip clearances in the water and gas-liquid two-phase cases by using the ANSYS CFX software and the results are verified with experimental data. It is shown the greater pressure fluctuation intensity corresponds with the TLV both in the water and gas-liquid two-phase cases. In the meantime, the location of the maximum pressure fluctuation intensity is related to the tip clearance size. In addition, for different tip clearances, the pressure fluctuation intensity with the rotor and stator interaction (RSI) is relatively larger. The difference is that when Rtc = 1.5 mm , the pressure fluctuation intensity near the impeller middle point is also relatively larger. On the whole, the pressure fluctuation intensity in the gas-liquid two-phase case is larger than that in the water case. Furthermore, the gas causes the frequency of the high-amplitude pressure fluctuation in the impeller and the diffuser to be shifted from 7 fn (fn denotes impeller rotational frequency) and 3 fn to the low-frequency region, respectively. The pressure fluctuations at the blade-passing frequency (BPF) and the multiple BPFs gradually disappear. Meanwhile, the amplitude at the dominant frequency in the gas-liquid two-phase case is at least one order of magnitude smaller than that in the water case, and the peak-to-peak value of the pressure fluctuation is also much smaller. [ABSTRACT FROM AUTHOR]

By tuning the spacer length of flexible bis(5,6-dimethylbenzimidazole) ligands, three nickel(II) coordination polymers {[Ni(L1)(tbta)(HO)]·HO} ( 1), {[Ni(L2)(tbta)(HO)·HO]} ( 2) and {[Ni(L3)(tbta)]·5HO} ( 3) (L1 = 1,4-bis(5,6-dimethylbenzimidazole)butane, L2 = 1,3-bis(5,6-dimethylbenzimidazole)propane and L3 = 1,1′-bis(5,6-dimethylbenzimidazole)methane, Htbta = tetrabromoterephthalic acid) were synthesized under hydrothermal conditions. These complexes were characterized by physico-chemical and spectroscopic methods and by single-crystal diffraction. All the three complexes feature 2D {4·6} sql/Shubnikov tetragonal plane networks. Complex 1 is further extended into a 3D supramolecular framework via weak C-H···O hydrogen-bonding interactions. Complex 3 shows a 3D supramolecular network through π- π stacking interactions. The fluorescence properties and catalytic activities of these complexes for the degradation of Congo red azo dye in a Fenton-like process were investigated. [ABSTRACT FROM AUTHOR]

With the increasing diversity of application needs and computing units, the server with heterogeneous processors is more and more widespread. However, conventional SMP/ccNUMA server architecture introduces communication bottleneck between heterogeneous processors and only uses heterogeneous processors as coprocessors, which limits the efficiency and flexibility of using heterogeneous processors. To solve this problem, this paper proposes an intra-server interconnect fabric that supports both intra-server peer-to-peer interconnection and I/O resource sharing among heterogeneous processors. By connecting processors and I/O devices with the proposed fabric, heterogeneous processors can perform direct communication with each other and run in stand-alone mode with shared intra-server resources. We design the proposed fabric by extending the de-facto system I/O bus protocol PCIe (Peripheral Computer Interconnect Express) and implement it with a single chip cZodiac. By making full use of PCIe's original advantages, the interconnection and the I/O sharing mechanism are light weight and efficient. Evaluations that have been carried out on both the FPGA (Field Programmable Gate Array) prototype and the cycle-accurate simulator demonstrate that our design is feasible and scalable. In addition, our design is suitable for not only the heterogeneous server but also the high density server. [ABSTRACT FROM AUTHOR]

Background and aims: Organic amendments are an option in enhancing soil biological productivity. Limited research exists on the effects of long-term cattle manure addition on low-molecular-weight organic acids (LMWOAs) concentrations in corn ( Zea mays L) and soybean ( Glycine max L.) fields in the region of soil erosion. The purpose of this study was to investigate the potential influence of cattle manure on the LMWOAs concentration in erosion soil. Methods: A field experiment was established in Hailun city, Northeast China to determine the impact of long-term cattle manure addition on the total amounts of main LMWOAs in eroded Mollisol fields. There were three levels of simulated-erosion, which removed 0, 10 and 30 cm of topsoil. Two soil amendments were: (1) chemical fertilizer at the rate normally used by farmers in the region and (2) chemical fertilizer plus 15,000 kg ha (dry weight basis) of cattle manure. Main LMWOAs in soil were assessed at the flowering stage of soybean and the jointing stage of corn. Principle results: Compared to chemical fertilizer alone, 7-years of repeated cattle manure addition significantly increased total amounts of main LMWOAs in rhizosphere about 9-70 times and bulk soil about 6-62 times. The magnitude of increase by cattle manure was in the order of oxalate>malate>malonate>lactate>maleate in corn plots, and oxalate>malate>malonate>lactate in soybean plots. In comparison, cattle manure and topsoil removal had larger effect on LMWOAs concentrations in corn plot than soybean plot. The addition of cattle manure application and top soil removal had significant independent influence on main LMWOAs concentration in soil solution. Conclusion: This study suggested that addition of cattle manure would be an effective approach in modifying soil biological properties through the increases in low-molecular-weight organic acids to eroded Chinese Mollisols. [ABSTRACT FROM AUTHOR]