Filling metal-organic framework mesopores with TiO2 for CO2 photoreduction.

Metal-organic frameworks (MOFs)1-3 are known for their specific interactions with gas molecules4,5; this, combined with their rich and ordered porosity, makes them promising candidates for the photocatalytic conversion of gas molecules to useful products6. However, attempts to use MOFs or MOF-based composites for CO2 photoreduction6-13 usually result in far lower CO2 conversion efficiency than that obtained from state-of-the-art solid-state or molecular catalysts14-18, even when facilitated by sacrificial reagents. Here we create 'molecular compartments' inside MOF crystals by growing TiO2 inside different pores of a chromium terephthalate-based MOF (MIL-101) and its derivatives. This allows for synergy between the light-absorbing/electron-generating TiO2 units and the catalytic metal clusters in the backbones of MOFs, and therefore facilitates photocatalytic CO2 reduction, concurrent with production of O2. An apparent quantum efficiency for CO2 photoreduction of 11.3 per cent at a wavelength of 350 nanometres is observed in a composite that consists of 42 per cent TiO2 in a MIL-101 derivative, namely, 42%-TiO2-in-MIL-101-Cr-NO2. TiO2 units in one type of compartment in this composite are estimated to be 44 times more active than those in the other type, underlining the role of precise positioning of TiO2 in this system.

MOFs-derived CuO-Fe3O4@C with abundant oxygen vacancies and strong Cu-Fe interaction for deep mineralization of bisphenol A.

A novel CuO-Fe3O4 encapsulated in the carbon framework with abundant oxygen vacancies (CuO-Fe3O4@C) was successfully prepared by thermal conversion of Cu(OAc)2/Fe-metal organic framework. The as-prepared catalyst exhibited excellent peroxymonosulfate (PMS) activation performance, good recyclability and fast magnetic separation. Under optimal conditions, the added BPA (60 mg/L) could be completely removed by CuO-Fe3O4@C/PMS system within 15 min with the degradation rate constant (k) of 0.32 min-1, being 10.3 and 246.2 times that in CuO/PMS (0.031min-1) and Fe3O4/PMS (0.0013 min-1) system. A deep mineralization rate of BPA (＞80%) was achieved within 60 min. The results demonstrated the synergistic effect of bimetallic clusters, oxygen vacancies and carbon framework was a key benefit for the exposure of more active sites, the electron donor capacity and the mass transfer of substrates, thereby promoting the decomposition of BPA. Capture experiments and EPR indicated that 1O2 was the predominant reactive oxygen species (ROSs). The degradation routes of BPA and the activation mechanism of PMS were proposed. This study offers an opportunity to develop promising MOFs-derived hybrid catalysts with tailored structures and properties for the practical application of SR-AOPs.

Total value adjustment of Bermudan option valuation under pure jump Lévy fluctuations.

During the COVID-19 pandemic, many institutions have announced that their counterparties are struggling to fulfill contracts. Therefore, it is necessary to consider the counterparty default risk when pricing options. After the 2008 financial crisis, a variety of value adjustments have been emphasized in the financial industry. The total value adjustment (XVA) is the sum of multiple value adjustments, which is also investigated in many stochastic models, such as the Heston [B. Salvador and C. W. Oosterlee, Appl. Math. Comput. 391, 125489 (2020)] and Bates [L. Goudenège et al., Comput. Manag. Sci. 17, 163-178 (2020)] models. In this work, a widely used pure jump Lévy process, the Carr-Geman-Madan-Yor process has been considered for pricing a Bermudan option with various value adjustments. Under a pure jump Lévy process, the value of derivatives satisfies a fractional partial differential equation (FPDE). Therefore, we construct a method that combines Monte Carlo with a finite difference of FPDE to find the numerical approximation of exposure and compare it with the benchmark Monte Carlo simulation and Fourier-cosine series method. We use the discrete energy estimate method, which is different from the existing works, to derive the convergence of the numerical scheme. Based on the numerical results, the XVA is computed by the financial exposure of the derivative value.

Effects of Apolipoprotein Ε Îµ4 allele on early postoperative cognitive dysfunction after anesthesia.

BACKGROUND: Postoperative cognitive dysfunction (POCD) is one of the main causes of morbidity after noncardiac surgery; however, the pathogenic mechanisms of POCD have remained unclear until now. In this study, we performed a pilot study to investigate the association between apolipoprotein E (ApoE) ε4 and POCD in older patients undergoing intravenous anesthesia (IVA) and inhalation anesthesia (IAA). METHODS: In total, 180 patients from Shenzhen People's Hospital were recruited and randomly divided into an IVA group and an IAA group. The IVA group and IAA group received propofol and sevoflurane treatment, respectively. Within 7 days after surgery, the mini-mental state examination (MMSE) was used daily to assess the cognitive function of both groups of patients. The genotypes of the ApoE gene were detected using the restriction fragment length polymorphism technique. In addition, the serum levels of (soluble protein-100ß) S­100ß and (Interleukin- 6) L­6 were also analyzed. RESULTS: Compared to the preoperative and IVA groups, the MMSE score in the IAA group significantly decreased at 3 days after surgery. Furthermore, the IAA group had a higher percentage of patients who scored less than 25 points than the IVA group at 3 days after surgery. The decrease in the MMSE score was closely related to the ApoE ε4 allele in the IAA group, but this correlation was not observed in the IVA group. The levels of S­100ß and IL­6 were increased sharply in patients with the ε4/ε4 genotype who received IAA compared with IVA at 1 day after surgery. CONCLUSION: The results of the study indicated that the ApoΕ Îµ4/ε4 genotype was a risk factor for early POCD in older patients undergoing sevoflurane anesthesia.

A High-Resolution National-Scale Hydrologic Forecast System from a Global Ensemble Land Surface Model.

Warning systems with the ability to predict floods several days in advance have the potential to benefit tens of millions of people. Accordingly, large-scale streamflow prediction systems such as the Advanced Hydrologic Prediction Service or the Global Flood Awareness System are limited to coarse resolutions. This article presents a method for routing global runoff ensemble forecasts and global historical runoff generated by the European Centre for Medium-Range Weather Forecasts model using the Routing Application for Parallel computatIon of Discharge to produce high spatial resolution 15-day stream forecasts, approximate recurrence intervals, and warning points at locations where streamflow is predicted to exceed the recurrence interval thresholds. The processing method involves distributing the computations using computer clusters to facilitate processing of large watersheds with high-density stream networks. In addition, the Streamflow Prediction Tool web application was developed for visualizing analyzed results at both the regional level and at the reach level of high-density stream networks. The application formed part of the base hydrologic forecasting service available to the National Flood Interoperability Experiment and can potentially transform the nation's forecast ability by incorporating ensemble predictions at the nearly 2.7 million reaches of the National Hydrography Plus Version 2 Dataset into the national forecasting system.

Modeling greenup date of dominant grass species in the Inner Mongolian Grassland using air temperature and precipitation data.

This work was undertaken to examine the combined effect of air temperature and precipitation during late winter and early spring on modeling greenup date of grass species in the Inner Mongolian Grassland. We used the traditional thermal time model and developed two revised thermal time models coupling air temperature and precipitation to simulate greenup date of three dominant grass species at six stations from 1983 to 2009. Results show that climatic controls on greenup date of grass species were location-specific. The revised thermal time models coupling air temperature and precipitation show higher simulation parsimony and efficiency than the traditional thermal time model for five of 11 data sets at Bayartuhushuo, Xilinhot and Xianghuangqi, whereas the traditional thermal time model indicates higher simulation parsimony and efficiency than the revised thermal time models coupling air temperature and precipitation for the other six data sets at E'ergunayouqi, Ewenkeqi and Chaharyouyihouqi. The mean root mean square error of the 11 models is 4.9 days. Moreover, the influence of late winter and early spring precipitation on greenup date seems to be stronger at stations with scarce precipitation than at stations with relatively abundant precipitation. From the mechanism perspectives, accumulated late winter and early spring precipitation may play a more important role as the precondition of forcing temperature than as the supplementary condition of forcing temperature in triggering greenup. Our findings suggest that predicting responses of grass phenology to global climate change should consider both thermal and moisture scenarios in some semiarid and arid areas.

Design of an Agent-Based Model to Examine Population-Environment Interactions in Nang Rong District, Thailand.

The design of an Agent-Based Model (ABM) is described that integrates Social and Land Use Modules to examine population-environment interactions in a former agricultural frontier in Northeastern Thailand. The ABM is used to assess household income and wealth derived from agricultural production of lowland, rain-fed paddy rice and upland field crops in Nang Rong District as well as remittances returned to the household from family migrants who are engaged in off-farm employment in urban destinations. The ABM is supported by a longitudinal social survey of nearly 10,000 households, a deep satellite image time-series of land use change trajectories, multi-thematic social and ecological data organized within a GIS, and a suite of software modules that integrate data derived from an agricultural cropping system model (DSSAT - Decision Support for Agrotechnology Transfer) and a land suitability model (MAXENT - Maximum Entropy), in addition to multi-dimensional demographic survey data of individuals and households. The primary modules of the ABM are the Initialization Module, Migration Module, Assets Module, Land Suitability Module, Crop Yield Module, Fertilizer Module, and the Land Use Change Decision Module. The architecture of the ABM is described relative to module function and connectivity through uni-directional or bi-directional links. In general, the Social Modules simulate changes in human population and social networks, as well as changes in population migration and household assets, whereas the Land Use Modules simulate changes in land use types, land suitability, and crop yields. We emphasize the description of the Land Use Modules - the algorithms and interactions between the modules are described relative to the project goals of assessing household income and wealth relative to shifts in land use patterns, household demographics, population migration, social networks, and agricultural activities that collectively occur within a marginalized environment that is subjected to a suite of endogenous and exogenous dynamics.

Piezo-photocatalytic flexible PAN/TiO2 composite nanofibers for environmental remediation.

Mechanical vibrations and solar energy are ubiquitous in the environment. Hereon, we report the synergic enhancement of the oxidation by simultaneously harvesting solar and mechanical vibrations through flexible piezo and photocatalytic composite nanofiber mats. Surface enriched titanium dioxide nanoparticles incorporated in polyacrylonitrile (PAN/TiO2) nanofibers were synthesized using a single pot electrospinning process with well-defined fiber diameters with widely tunable loading density. By incorporating photocatalytic TiO2 in flexible piezoelectric PAN nanofiber support, piezoelectric fields generated under the mechanical deformation promote the separation of the photogenerated electrons and holes to accelerate oxidation of pollutants. Our results demonstrated that the catalytic activity of PAN/TiO2 nanofibers in photodegradation of Rhodamine B (RhB) can be greatly enhanced by environmental vibration-induced piezoelectricity of PAN nanofibers, with a maximum enhancement factor of ~2.5. The working mechanism for the enhanced photocatalytic activity of PAN/TiO2 nanofibers by the mechanical vibrations were attributed to the piezoelectric effect of PAN nanofibers, which could efficiently promote the separation of the photogenerated electrons and holes in the TiO2 nanoparticles. We believe the approach to enhancing the catalytic activity of mat can make full use of the polymer properties and natural energy, and it also can be extended to other composite polymer/semiconductor systems.

Investigation on the Controllable Synthesis of Colorized and Magnetic Polystyrene Beads With Millimeter Size via In Situ Suspension Polymerization.

A series of colorized and magnetic polystyrene/Fe3O4 (PS/Fe3O4) composite beads with millimeter size are successfully synthesized by introducing hydrophobic Fe3O4 via in situ suspension polymerization of styrene for the first time. Effects of the hydrophobic Fe3O4 content, stirring speed, and surfactant dosage on the macromorphology and particle size of PS/Fe3O4 beads are systematically investigated to realize the controllable synthesis. Moreover, three kinds of hydrophobic pigments are also employed to synthesize colorized polystyrene, which demonstrates the versatility, simplicity, and wide applicability of the proposed method. Scanning electron microscopy (SEM) and element mapping (EM) images demonstrated that the hydrophobic Fe3O4 is well dispersed in the polystyrene matrix. Thermogravimetric analysis (TGA) shows that the resultant PS/Fe3O4 beads possess a better thermal stability than neat PS. PS/Fe3O4 beads have a promising application in the fields of colorized extruded PS board, colorized expanded PS foam particle, and board.

Investigation on the Preparation of Rice Straw-Derived Cellulose Acetate and Its Spinnability for Electrospinning.

Rice straw-derived cellulose (RSC) with purity of 92 wt.% was successfully extracted from rice straw by a novel and facile strategy, which integrated the C2H5OH/H2O autocatalytic process, dilute alkali treatment and H2O2 bleaching process. Influencing factors of the cellulose extraction were systematically examined, such as ethanol concentration, alkali concentration, H2O2 bleaching process and so on; the optimal extraction conditions of cellulose was determined. A series of rice straw-derived cellulose acetate (RSCA) with different degree of substitution (DS) were prepared by the acetylation reaction; the effects of Ac2O/cellulose ratio, reaction temperature and reaction time on the acetylation reaction were investigated. Results of FTIR and XRD analysis demonstrated that highly purified RSC and RSCA were prepared comparing with the commercial cellulose and cellulose acetate. Solubility analysis of RSCA with different DS indicated as-prepared RSCA with DS of 2.82 possessed the best solubleness, which was suitable for electrospinning. Moreover, the flexible RSCA fibrous membrane was easily fabricated by a facile electrospinning method. Our proposed method provided a strategy for realizing the high-value utilization of waste rice straw resource, as prepared RSC and RSCA can be used as chemical raw material, and electrospun RSCA fibrous membrane has various applications in medical materials, food packaging, water purification and so on.

Polarization-Modulated Multidirectional Photothermal Actuators.

Photothermal actuators have attracted increasing attention due to their ability to convert light energy into mechanical deformation and locomotion. This work reports a freestanding, multidirectional photothermal robot that can walk along a predesigned pathway by modulating laser polarization and on-off switching. Magnetic-plasmonic hybrid Fe3 O4 /Ag nanorods are synthesized using an unconventional templating approach. The coupled magnetic and plasmonic anisotropy allows control of the rod orientation, plasmonic excitation, and photothermal conversion by simply applying a magnetic field. Once the rods are fixed with desirable orientations in a bimorph actuator by magnetic-field-assisted lithography, the bending of the actuator can be controlled by switching the laser polarization. A bipedal robot is created by coupling the rod orientation with the alternating actuation of its two legs. Irradiating the robot by a laser with alternating or fixed polarization synergistically results in basic movement (backward and forward) and turning (including left-, right-, and U-turn), respectively. A complex walk along predesigned pathways can be potentially programmed by combining the movement and turning modes of the robots. This strategy provides an alternative driving mechanism for preparing functional soft robots, thus breaking through the limitations in the existing systems in terms of light sources and actuation manners.

Janus Evaporators with Self-Recovering Hydrophobicity for Salt-Rejecting Interfacial Solar Desalination.

The recent advancements in interfacial evaporation of salty water using renewable solar energy provide one of the promising pathways to solve worldwide water scarcity. Pursuing a stable evaporation rate of water has been the central focus of this field, as it is directly related to the throughput, while salt deposition on the evaporator becomes a critical issue. Although Janus-structured evaporators with an upper hydrophobic layer and a bottom hydrophilic layer have been demonstrated as an effective way to suppress the salt precipitation, the hydrophobic upper layer, achieved usually by some special organic groups, suffers from a photochemical oxidation when exposed to oxidative chemicals in water and high-energy light, resulting in a deteriorated surface hydrophobicity. Here, we report our design of an efficient salt-rejecting Janus evaporator by taking advantage of the self-recovering surface hydrophobicity of poly(dimethylsiloxane) (PDMS) against photochemical damages, which ensures a long-term surface hydrophobicity. With its upper layer partially covered with PDMS, the Janus evaporator demonstrates an excellent salt rejection capability and exhibits a stable evaporation rate of 1.38 kg·m-2·h-1 under 1 sun illumination for 400 min of continuous operation, or 90 d of intermittent work. By combining the advantages of high structural integration, long-term salt-rejection, and efficient evaporation, our Janus evaporator holds great promise for the stable production of clean water from seawater.

Target-controlled infusion of propofol and remifentanil combined with dexmedetomidine reduces functional endoscopic sinus surgery bleeding.

The aim of the present study was to investigate the effects of target-controlled infusion (TCI) of propofol and remifentanil combined with dexmedetomidine on functional endoscopic sinus surgery (FESS) bleeding and surgical field. 62 patients scheduled to undergo FESS were randomly divided into experimental group (intravenous 0.5 µg kg-1 h-1 dexmedetomidine after 0.5 µg kg-1 bolus within 15 min until the end of surgery) or control group (intravenous saline administration at the same dose). All patients underwent endotracheal intubation under general anesthesia with TCI of propofol and remifentanil for anesthesia induction and maintenance. During anesthesia, arterial pressure (MAP), heart rate (HR), intraoperative propofol and remifentanil dosage and intraoperative blood loss were recorded. Surgeons rated their satisfaction with the surgical field using the Numeric Rating Scale (NRS). Following surgery, visual analog scale (VAS) was assessed. During tracheal intubation and extubation, HR and MAP in the experimental group were significantly lower compared with the control group (P<0.05); HR was also significantly lower compared with the control group throughout surgery (P<0.05). The mean infusion rate of propofol and remifentanil was significantly lower in the experimental group compared with the control group (P=0.001 and P=0.045, respectively). Blood loss in the experimental group was significantly lower compared with the control group (P=0.007). NRS and VAS scores in the experimental group were significantly improved compared with control group (P<0.01). In conclusion, TCI of propofol and remifentanil for FESS combined with dexmedetomidine reduced intraoperative bleeding and improved the quality of surgical field compared with the same procedure without dexmedetomidine. Dexmedetomidine also reduced the increase in MAP and HR during tracheal intubation and extubation, and improved postoperative analgesia quality.