Dynamical properties of quantum many-body systems with long range interactions

Employing large-scale quantum Monte Carlo simulations, we systematically compute the energy spectra of the 2D spin-1/2 Heisenberg model with long-range interactions. With the $1/r^{\alpha}$ ferromagnetic and staggered antiferromagnetic interactions, we find the explicit range in $\alpha$ for {\color{black} the short-range Goldstone-type (gapless), anomalous Goldstone-type (gapless) and Higgs-type (gapped) spectra. Accompanied by the spin wave analysis, our numerical results vividly reveal how the long-range interactions alter the usual linear and quadratic magnon dispersions in 2D quantum magnets and give rise to anomalous dynamical exponents. Moreover, we find explicit case where the gapped excitation exists even when the Hamiltonian is extensive. This work provides the first set of unbiased dynamical data} of long-range quantum many-body systems and suggests that many universally accepted low-energy customs for short-range systems need to be substantially modified for long-range ones which are of immediate relevance to the ongoing experimental efforts from quantum simulators to 2D quantum moir\'e materials.Comment: 5 pages,3 figure

Identification of the function of extracellular polymeric substances (EPS) in denitrifying phosphorus removal sludge in the presence of copper ion

Industrial wastewater containing heavy metals that enters municipal wastewater treatment plants inevitably has a toxic impact on biological treatment processes. In this study, the impact of Cu(II) (0, 1.5, 2, 2.5, 3mg/L) on the performance of denitrifying phosphorus removal (DPR) and microbial community structures was investigated. Particularly, the dynamic change in the amount and composition of extracellular polymeric substances (EPS), and the role of EPS in P removal, were assessed using three-dimensional excitation-emission matrix fluorescence spectroscopy combined with parallel factor (PARAFAC) analysis. The results showed that, after long-term adjustment, the P removal efficiency was maintained at 95±2.7% at Cu(II) addition up to 2.5mg/L, but deteriorated when the Cu(II) addition was 3mg/L. The EPS content, including proteins and humic substances, increased with increasing Cu(II) additions at concentrations ≤2.5mg/L. This property of EPS was beneficial for protecting phosphate-accumulating organisms (PAOs) against heavy metals, as both proteins and humic substances are strong ligands for Cu(II). Therefore, the PAOs abundance was still relatively high (67±3%) when Cu(II) accumulation in sludge was up to 10mg/g SS. PARAFAC confirmed that aromatic proteins could be transformed into soluble microbial byproduct-like material when microorganisms were subjected to Cu(II) stress, owing to their strong metal ion complexing capacity. The increase in the percentage of humic-like substances enhanced the detoxification function of the sludge EPS. EPS accounted for approximately 26-47% of P removed by adsorption when Cu(II) additions were between 0 and 2.5mg/L. The EPS function, including binding toxic heavy metals and P storage, enhanced the operating stability of DPR systems. This study provides us with a better understanding of (1) the tolerance of DPR sludge to copper toxicity and (2) the function of sludge EPS in the presence of heavy metals in biological P removal systems

Pathways towards regional circular economy evaluated using material flow analysis and system dynamics

Circular Economy (CE) offers insights to sustainable production and consumption by integrating environmental analysis to the socioeconomic system. To promote sustainable development in Guangdong Province, this study integrates System Dynamics (SD) and Material Flow Analysis (MFA) into CE theories to establish a framework to comprehensively evaluate regional economies. Nine development scenarios are further developed to provide strategic recommendations for the development of CE in Guangdong. The results of these scenarios show that the CE of Guangdong is most effective among the nine scenarios when the birth rate is reduced by about 2%, the growth rates of the primary and secondary industries are reduced by 2%, and the growth rate of the tertiary industry increased by 2%. The biological substance consumption, fossil fuel consumption, building mineral consumption, industrial exhaust emissions and solid waste emissions are 88.39 Mt, 86.63 Mt, 108.16 Mt, 280.90 Mt, and 69.02 Mt respectively. The total material input (TMI) of 10,000 RMB of GDP and the total material output (TMO) of 10,000 RMB of GDP are 49.64 kt/10,000 RMB and 42.70 kt/10,000 RMB in 2022 respectively. Based on the status quo and simulated results, this study acknowledges the importance of population control and highlights the vigorous development of tertiary industry in economic construction. Policy interventions such as building pilot demonstrative smart cities and industrial parks would facilitate long-term sustainability of urban systems

The comparison: photoluminescence and afterglow behavior in CaSnO3:Dy3+ and Ca2SnO4:Dy3+ phosphors

This paper reports the comparison of photoluminescence and afterglow behavior of Dy3+ in CaSnO3 and Ca2SnO4 phosphors. The samples containing CaSnO3 and Ca2SnO4 were prepared via solid-state reaction. The properties have been characterized and analyzed by utilizing X-ray diffraction (XRD), photoluminescence spectroscope (PLS), X-ray photoelectron spectroscopy (XPS), afterglow spectroscopy (AS) and thermal luminescence spectroscope (TLS). The emission spectra revealed that CaSnO3:Dy3+ and Ca2SnO4:Dy3+ phosphors showed different photoluminescence. The Ca2SnO4:Dy3+ phosphor showed a typical F-4(9/2) to H-6(j) energy transition of Dy3+ ions, with three significant emissions centering around 482, 572 and 670 nm. However, the CaSnO3:Dy3+ phosphor revealed a broad T-1 -> S-0 transitions of Sn2+ ions. The XPS demonstrate the existence of Sn2+ ions in CaSnO3 phosphor caused by the doping of Dy3+ ions. Both the CaSnO3:Dy3+ and Ca2SnO4:Dy3+ phosphors showed a typical triple-exponential afterglow when the UV source switched off. Thermal simulated luminescence study indicated that the persistent afterglow of CaSnO3:Dy3+ and Ca2SnO4:Dy3+ phosphors was generated by the suitable electron or hole traps which were resulted from the doping the calcium stannate host with rare-earth ions (Dy3+)

Nitric oxide and nitrous oxide emissions from a full-scale activated sludge anaerobic/anoxic/oxic process

Both nitric oxide (NO) and nitrous oxide (NO) have strong negative effects on the environment. Although NO emissions in wastewater water treatment plants (WWTPs) have been widely studied, the concurrence of NO and NO emissions has not been well characterized, and their emission status from WWTPs in China is still not clear. In this study, online NO and NO analyzers were used to investigate spatial and temporal variations of NO and NO emissions in a full-scale activated sludge anaerobic/anoxic/oxic (A/O) process over one year. The amoA gene of ammonia oxidation bacteria and the nosZ gene of denitrifiers were analyzed to identify possible NO and NO production pathways. The emission factors of NO and NO in the studied A/O process were 0.01±0.006% (0.002-0.021%) and 1.29±1.07% (0.095-3.44%) of the nitrogen load, respectively. Both NO and NO were mainly emitted from the oxic zone, with emitting levels increasing greatly from the initial oxic zone to the zone end. The NO emission pattern closely resembled that of NO emissions, but the emission amounts were 2-3 magnitudes higher than that of NO. Nitrite accumulation directly triggered NO and NO production. This study provides novel insights into emission characteristics and the production pathways of both NO and NO from a full-scale A/O process, which is of great significance toward development of effective mitigation strategies for NO and NO emissions from WWTPs

Effect of Microstructure on the Thermal Conductivity of Plasma Sprayed Y2O3 Stabilized Zirconia (8% YSZ)

In this paper, the effect of microstructure on the thermal conductivity of plasma-sprayed Y2O3 stabilized ZrO2 (YSZ) thermal barrier coatings (TBCs) is investigated. Nine freestanding samples deposited on aluminum alloys are studied. Cross-section morphology such as pores, cracks, m-phase content, grain boundary density of the coated samples are examined by scanning electron microscopy (SEM) and electron back-scattered diffraction (EBSD). Multiple linear regressions are used to develop quantitative models that describe the relationship between the particle parameters, m-phase content and features of the microstructure such as porosity, crack-porosity, and the length density of small and big angle-cracks. Moreover, the relationship between the microstructure and thermal conductivity is investigated. Results reveal that the thermal conductivity of the coating is mainly determined by the microstructure and grain boundary density at room temperature (25 °C), and by the length density of big-angle-crack, monoclinic phase content and grain boundary density at high temperature (1200 °C)

污水生物处理实际工艺中氧化亚氮的释放:现状与挑战

The pathways for nitrous oxide (NO) production from biological nitrogen removal processes in wastewater treatment plants (WWTPs) are illustrated. Comparative analyses of NO emissions from some typical wastewater treatment processes are conducted and the mechanisms for their discrepancy are discussed in detail. The methods for reduction of NO emission are proposed. According to the recommended NO emissions factors, the gross quantity of NO emissions from WWTPs in China is estimated to be 1.26×10g in 2011. Further study on NO emissions from biological wastewater treatment processes is recommended