Removal of Nickel(II) from Aqueous Solution by Complexation- Ultrafiltration with Polyvinyl Pyrrolidone

This study confers insight into the removal of Nickel(II) from aqueous solution by complexation-ultrafiltration (CP-UF) technique with water-soluble polymer polyvinyl pyrrolidone (PVP). The whole experiment process includes five parts: pre-treatment, CP-UF, concentration, decomplexation and regeneration of polymer. Numerous factors affecting the retention rate of Nickel(II) (RNi) and permeate flux (J), such as pH, loading ratio, transmembrane pressure (TMP), complexation time and added salt have been investigated. In the CP-UF process, RNi reaches nearly 94% while pH of 7, loading ratio of 4, TMP of 1.0 bar, temperature of 250C, complexation time of 30 min are chosen to be the optimal parameters. In the process of concentration, J declines slowly and RNi is very high at loading ratio of 4 and pH of 7. Nickel ion concentration in the retentate solution increases linearly with volume concentration factor. In the process of decomplexation, the decomplexation percentage of nickel(II)-PVP complex reaches 42%. The binding capacity of the regenerated PVP is close to that of fresh PVP, and the recovery percentage of binding capacity is higher than 90%

Evaluating the Perceived Safety of Urban City via Maximum Entropy Deep Inverse Reinforcement Learning

Inspired by expert evaluation policy for urban perception, we proposed a novel inverse reinforcement learning (IRL) based framework for predicting urban safety and recovering the corresponding reward function. We also presented a scalable state representation method to model the prediction problem as a Markov decision process (MDP) and use reinforcement learning (RL) to solve the problem. Additionally, we built a dataset called SmallCity based on the crowdsourcing method to conduct the research. As far as we know, this is the first time the IRL approach has been introduced to the urban safety perception and planning field to help experts quantitatively analyze perceptual features. Our results showed that IRL has promising prospects in this field. We will later open-source the crowdsourcing data collection site and the model proposed in this paper.Comment: ACML2022 Camera-ready Versio

Quantum tunneling rotor as a sensitive atomistic probe of guests in a metal-organic framework

Quantum tunneling rotors in a zeolitic imidazolate framework ZIF-8 can provide insights into local gas adsorption sites and local dynamics of porous structure, which are inaccessible to standard physisorption or x-ray diffraction sensitive primarily to long-range order. Using in situ high-resolution inelastic neutron scattering at 3 K, we follow the evolution of methyl tunneling with respect to the number of dosed gas molecules. While nitrogen adsorption decreases the energy of the tunneling peak, and ultimately hinders it completely (0.33 meV to zero), argon substantially increases the energy to 0.42 meV. Ab initio calculations of the rotational barrier of ZIF-8 show an exception to the reported adsorption sites hierarchy, resulting in anomalous adsorption behavior and linker dynamics at subatmospheric pressure. The findings reveal quantum tunneling rotors in metal-organic frameworks as a sensitive atomistic probe of local physicochemical phenomena.MMC Laboratory is supported by the ERC Consolidator Grant (PROMOFS Grant Agreement No. 771575) and EPSRC Awards (Grants No. EP/N014960/1 and No. EP/R511742/1). We thank ISIS Facility for the awarded OSIRIS beamtime (Grants No. RB1410426, No. RB1510529, and No. RB1610180), DOIs 10.5286/ISIS.E.RB1410426, 10.5286/ISIS.E.RB1510529, and 10.5286/ISIS.E.RB1610180, as well as the Cryogenics, and Pressure & Furnaces teams for their exemplary support. M.R.R. acknowledges the U.S. DOE Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division (Separation Sciences). This work is further supported by the Fund for Scientific Research Flanders (FWO) through a Ph.D. fellowship for A.L. (Grant No. 11D2220N) and a postdoctoral fellowship for S.M.J.R. (Grant No. 12T3522N). Financial support for F.F.-A. from the Spanish Ministry of Science and Innovation (Grant No. PID2020-114506GBI00 funded by MCIN/AEI/10.13039/501100011033 and Grant No. TED2021-129457B-I00 funded by MCIN/AEI/10.13039/501100011033 and the European Union NextGenerationEU/PRTR) as well as the Basque Government (Grant No. PIBA-2021-0026) is gratefully acknowledged. We also acknowledge the financial support received from the IKUR Strategy under the collaboration agreement between Ikerbasque Foundation and the Materials Physics Center on behalf of the Department of Education of the Basque Government.Peer reviewe

Effects of Domestic Tourism on Urban-Rural Income Inequality: Evidence from China

Most studies examining the relationship between domestic tourism and urban-rural income inequality have found a positive correlation. However, the causal link between them is difficult to establish due to many potential sources of endogeneity. By including World Heritage Site (henceforth WHS) designation in the set of instruments, this paper estimates the causal effects of domestic tourism on urban-rural income inequality within 31 China’s provinces from 1998 to 2018. Our results show that developing domestic tourism can reduce urban-rural income inequality by raising income of rural residents more than twice as much as that of urban residents. Specifically, a 10% increase in domestic tourism earnings could increase the average disposable income of urban residents by 0.35% and that of rural residents by 0.94%, resulting in a 0.59% reduction in the urban-rural income ratio. According to channels analysis, domestic tourism enhances the disposable income of rural residents mainly through raising household operating income from agriculture, manufacturing, and services

Quantitative studies of the nanoscale mechanical properties of metal organic framework materials

The nanoscale mechanical properties of metal-organic framework (MOF) materials including the elasticity (Young’s modulus), plasticity (hardness, yield stress, ultimate strength, and work hardening coefficient), adhesion property (adhesive force and energy), and failure mechanisms (failure modes, corresponding threshold forces and failure strengths) have been studied in the range of sub-nm to ~100s nm in depth. MOF materials are a topical class of porous crystalline solids that are constructed from the self-assembly of metal clusters and organic linkers, to yield tuneable framework structures with a vast range of physical and chemical properties. Herein, three model MOF systems are of particular interest: the nanocrystals and micron-sized crystals of ZIF-8, two-dimensional nanosheets of CuBDC, and submillimetre-sized crystals of HKUST-1. The three MOF materials were prudently selected because they represent three distinctive structures in terms of the response to stress. In this work, depth-sensing nanoindentation techniques, particularly the ‘conventional’ instrumented indentation technique (force sensitivity ~ 50 nN) and the atomic force microscopy (AFM)-based nanoindentation (force sensitivity &lt; 0.05 nN), have been intensively employed and adapted to enable the accurate characterisation of the fine-scale mechanical behaviour of MOF materials. By leveraging the force and displacement sensitivities of the AFM instrument, the AFM-based nanoindentation method has been rationally established and improved by extending its application to study MOF mechanics at the nanoscale. This is a challenging field that has not yet been rigorously addressed by means of detailed experiments. Amongst the depth-sensing techniques, the AFM-based nanoindentation measurements are usually criticised for their instability and low reproducibility. Herein, the major factors that could interfere with the measurement precision have been systematically investigated. The research has led to the development of comprehensive approaches for AFM instrumental controls to achieve reliable force-displacement data and improved contact models for nanoindentation data analysis. Quantification of the nanoscale mechanical properties sheds light on the complicated deformation behaviour of the porous MOF structures. AFM nanoindentation data obtained at the nanometre length scale reveal new structure-property information about the surface energy, incipient plasticity, and fracture mechanisms underpinning the inorganic-organic building blocks of MOF systems. Accurate materials data about mechanical performance and durability will be fundamental towards the development of functional devices and practical applications.</p