Simultaneous electrocoagulation and E-peroxone coupled with ultrafiltration membrane for shale gas produced water treatment.

Membrane fouling caused by the organics-coated particles was the main obstacle for the highly efficient shale gas produced water (SGPW) treatment and recycling. In this study, a novel hybrid electrocoagulation (EC) and E-peroxone process coupled with UF (ECP-UF) process was proposed to examine the efficacy and elucidate the mechanism for UF fouling mitigation in assisting SGPW reuse. Compared to the TMP (transmembrane pressure) increase of -15 kPa in the EC-UF process, TMP in ECP-UF system marginally increased to -1.4 kPa for 3 filtration cycles under the current density of 15 mA/cm2. Both the total fouling index and hydraulically irreversible fouling index of the ECP-UF process were significantly lower than those of EC-UF process. According to the extended Derjaguin-Landau-Verwey-Overbeek theory, the potential barriers was the highest for ECP-UF processes due to the substantial increase of the acid-base interaction energy in ECP-UF process, which was well consistent with the TMP and SEM results. Turbidity and TOC of ECP-UF process were 63.6% and 45.8% lower than those of EC-UF process, respectively. According to the MW distribution, the variations of compounds and their relative contents were probably due to the oxidation and decomposing products of the macromolecular organics. The number of aromatic compound decreased, while the number of open-chain compounds (i.e., alkenes, alkanes and alcohols) increased in the permeate of ECP-UF process. Notably, the substantial decrease in the relative abundance of di-phthalate compounds was attributed to the high reactivity of these compounds with ·OH. Mechanism study indicated that ECP could realize the simultaneous coagulation, H2O2 generation and activation by O3, facilitating the enhancement of ·OH and Alb production and therefore beneficial for the improved water quality and UF fouling mitigation. Therefore, the ECP-UF process emerges as a high-efficient and space-saving approach, yielding a synergistic effect in mitigating UF fouling for SGPW recycling.

Exploring quasiprobability approaches to quantum work in the presence of initial coherence: Advantages of the Margenau-Hill distribution.

In quantum thermodynamics, the two-projective-measurement (TPM) scheme provides a successful description of stochastic work only in the absence of initial quantum coherence. Extending the quantum work distribution to quasiprobability is a general way to characterize work fluctuation in the presence of initial coherence. However, among a large number of different definitions, there is no consensus on the most appropriate work quasiprobability. In this article, we list several physically reasonable requirements including the first law of thermodynamics, time-reversal symmetry, positivity of second-order moment, and a support condition for the work distribution. We prove that the only definition that satisfies all these requirements is the Margenau-Hill (MH) quasiprobability of work. In this sense, the MH quasiprobability of work shows its advantages over other definitions. As an illustration, we calculate the MH work distribution of a breathing harmonic oscillator with initial squeezed states and show the convergence to classical work distribution in the classical limit.

Heat statistics in the relaxation process of the Edwards-Wilkinson elastic manifold.

The stochastic thermodynamics of systems with a few degrees of freedom has been studied extensively so far. We would like to extend the study to systems with more degrees of freedom and even further-continuous fields with infinite degrees of freedom. The simplest case for a continuous stochastic field is the Edwards-Wilkinson elastic manifold. It is an exactly solvable model of which the heat statistics in the relaxation process can be calculated analytically. The cumulants require a cutoff spacing to avoid ultraviolet divergence. The scaling behavior of the heat cumulants with time and the system size as well as the large deviation rate function of the heat statistics in the large size limit is obtained.

Hierarchical structure of fluctuation theorems for a driven system in contact with multiple heat reservoirs.

For driven open systems in contact with multiple heat reservoirs, we find the marginal distributions of work or heat do not satisfy any fluctuation theorem, but only the joint distribution of work and heat satisfies a family of fluctuation theorems. A hierarchical structure of these fluctuation theorems is discovered from microreversibility of the dynamics by adopting a step-by-step coarse-graining procedure in both classical and quantum regimes. Thus, we put all fluctuation theorems concerning work and heat into a unified framework. We also propose a general method to calculate the joint statistics of work and heat in the situation of multiple heat reservoirs via the Feynman-Kac equation. For a classical Brownian particle in contact with multiple heat reservoirs, we verify the validity of the fluctuation theorems for the joint distribution of work and heat.

Optimizing Brownian heat engine with shortcut strategy.

Shortcuts to isothermality provide a powerful method to speed up quasistatic thermodynamic processes within finite-time manipulation. We employ the shortcut strategy to design and optimize Brownian heat engines, and we formulate a geometric description of the energetics with the thermodynamic length. We obtain a tight and reachable bound of the output power for shortcut-driven heat engines. The bound is reached by the optimal shortcut protocol to vary the control parameters with a proper constant velocity of the thermodynamic length. With the shortcut strategy, we optimize the control of Brownian heat engines to achieve the maximum power in the general-damped situation. We also derive the efficiency at the maximum power and the maximum power at the given efficiency for shortcut-driven heat engines.

Minimal energy cost to initialize a bit with tolerable error.

Landauer's principle imposes a fundamental limit on the energy cost to perfectly initialize a classical bit, which is only reached under the ideal operation with infinitely long time. The question on the cost in the practical operation for a bit has been raised under the constraint by the finiteness of operation time. We discover a raise-up of energy cost by L^{2}(ε)/τ from the Landaeur's limit (k_{B}Tln2) for a finite-time τ initialization of a bit with an error probability ε. The thermodynamic length L(ε) between the states before and after initializing in the parametric space increases monotonously as the error decreases. For example, in the constant dissipation coefficient (γ_{0}) case, the minimal additional cost is 0.997k_{B}T/(γ_{0}τ) for ε=1% and 1.288k_{B}T/(γ_{0}τ) for ε=0.1%. Furthermore, the optimal protocol to reach the bound of minimal energy cost is proposed for the bit initialization realized via a finite-time isothermal process.

Microscopic theory of the Curzon-Ahlborn heat engine based on a Brownian particle.

The Curzon-Ahlborn (CA) efficiency, as the efficiency at the maximum power (EMP) of the endoreversible Carnot engine, has significant impact on finite-time thermodynamics. However, the CA engine is based on many assumptions. In the past few decades, although a lot of efforts have been made, a microscopic theory of the CA engine is still lacking. By adopting the method of the stochastic differential equation of energy, we formulate a microscopic theory of the CA engine realized with a highly underdamped Brownian particle in a class of nonharmonic potentials. This theory gives microscopic interpretation of all assumptions made by Curzon and Ahlborn. In other words, we find a microscopic counterpart of the CA engine in stochastic thermodynamics. Also, based on this theory, we derive the explicit expression of the protocol associated with the maximum power for any given efficiency, and we obtain analytical results of the power and the efficiency statistics for the Brownian CA engine. Our research brings new perspectives to experimental studies of finite-time microscopic heat engines featured with fluctuations.

Geodesic Path for the Minimal Energy Cost in Shortcuts to Isothermality.

Shortcuts to isothermality are driving strategies to steer the system to its equilibrium states within finite time, and enable evaluating the impact of a control promptly. Finding the optimal scheme to minimize the energy cost is of critical importance in applications of this strategy in pharmaceutical drug tests, biological selection, and quantum computation. We prove the equivalence between designing the optimal scheme and finding the geodesic path in the space of control parameters. Such equivalence allows a systematic and universal approach to find the optimal control to reduce the energy cost. We demonstrate the current method with examples of a Brownian particle trapped in controllable harmonic potentials.

Quantum-Classical Correspondence Principle for Heat Distribution in Quantum Brownian Motion.

Quantum Brownian motion, described by the Caldeira-Leggett model, brings insights to the understanding of phenomena and essence of quantum thermodynamics, especially the quantum work and heat associated with their classical counterparts. By employing the phase-space formulation approach, we study the heat distribution of a relaxation process in the quantum Brownian motion model. The analytical result of the characteristic function of heat is obtained at any relaxation time with an arbitrary friction coefficient. By taking the classical limit, such a result approaches the heat distribution of the classical Brownian motion described by the Langevin equation, indicating the quantum-classical correspondence principle for heat distribution. We also demonstrate that the fluctuating heat at any relaxation time satisfies the exchange fluctuation theorem of heat and its long-time limit reflects the complete thermalization of the system. Our research study justifies the definition of the quantum fluctuating heat via two-point measurements.

Extrapolating the thermodynamic length with finite-time measurements.

The thermodynamic length, though providing a lower bound for the excess work required in a finite-time thermodynamic process, is determined by the properties of the equilibrium states reached by the quasistatic process and is thus beyond the direct experimental measurement. We propose an experimental strategy to measure the thermodynamic length of an open classical or quantum system by extrapolating finite-time measurements. The current proposal enables the measurement of the thermodynamic length for a single control parameter without requiring extra effort to find the optimal control scheme, and is illustrated with examples of the quantum harmonic oscillator with tuning frequency and the classical ideal gas with changing volume. Such a strategy shall shed light on the experimental design of the lacking platforms to measure the thermodynamic length.

Maximum Entropy Approach to Reliability of Multi-Component Systems with Non-Repairable or Repairable Components.

The degradation and recovery processes are multi-scale phenomena in many physical, engineering, biological, and social systems, and determine the aging of the entire system. Therefore, understanding the interplay between the two processes at the component level is the key to evaluate the reliability of the system. Based on the principle of maximum entropy, an approach is proposed to model and infer the processes at the component level, and is applied to repairable and non-repairable systems. By incorporating the reliability block diagram, this approach allows for integrating the information of network connectivity and statistical moments to infer the hazard or recovery rates of the degradation or recovery processes. The overall approach is demonstrated with numerical examples.

Simulating Finite-Time Isothermal Processes with Superconducting Quantum Circuits.

Finite-time isothermal processes are ubiquitous in quantum-heat-engine cycles, yet complicated due to the coexistence of the changing Hamiltonian and the interaction with the thermal bath. Such complexity prevents classical thermodynamic measurements of a performed work. In this paper, the isothermal process is decomposed into piecewise adiabatic and isochoric processes to measure the performed work as the internal energy change in adiabatic processes. The piecewise control scheme allows the direct simulation of the whole process on a universal quantum computer, which provides a new experimental platform to study quantum thermodynamics. We implement the simulation on ibmqx2 to show the 1/τ scaling of the extra work in finite-time isothermal processes.

Cross-Linked Covalent Organic Framework-Based Membranes with Trimesoyl Chloride for Enhanced Desalination.

The rational design of continuous covalent organic framework (COF)-based membranes is challenging for desalination applications, mainly due to the larger intrinsic pore size of COFs and defects in the crystalline film, which lead to a negligible NaCl rejection ratio. In this work, we first demonstrated a COF-based desalination membrane with in situ cross-linking of a COF-TpPa layer by trimesoyl chloride (TMC) to stitch the defects between COF crystals and cross-link the COF cavity with high-cross-linking degree networks to enhance NaCl rejection. With the addition of TMC monomers, both small spherical nodules and some elongated "leaf-like" features were observed on the membrane surface due to the appearance of nanovoids during cross-linking. The resulting COF-based desalination membrane had a water permeability of approximately 0.81 L m-2 h-1 bar-1 and offered substantial enhancement of the NaCl rejection ratio from being negligible to 93.3% at 5 bar. Mechanistic analysis indicated that the amidation reaction of the secondary amine in keto COF with TMC induced the formation of a highly porous network structure both in the cavity and on the exterior of COF, thereby successfully forming a continuous and nanovoid-containing selective layer for desalination. In addition, the membrane exhibited excellent desalting performance for real industrial wastewater with both low and high salinity. This study proposed that the introduction of a cross-linker to react with the terminal amine group and secondary amine in the backbone of the keto form of COF or its derivatives could provide a facile and scalable approach to fabricate a COF-based membrane with superior NaCl rejection. This opens a new fabrication route for COF-based desalination membranes, as well as extended applications in water desalination.

The synergistic effect of electrocoagulation coupled with E-peroxone process for shale gas fracturing flowback water treatment.

Electrocoagulation (EC) coupled with E-peroxone process (ECP) was a promising and cost-effective integrated technology for shale gas fracturing flowback water (SGFFW) treatment. In this study, the ECP process was comprehensively compared with two sequential processes (EC followed by E-peroxone (EC-E-peroxone) and E-peroxone followed by EC (E-peroxone-EC)) to elucidate the synergistic effect of this coupled process. In EC-E-peroxone process, COD decreased by 89.2%, while COD decreased by 82.5% for 180 min in E-peroxone-EC process. However, COD removal efficiency was 82.4% in ECP for only 90 min. Average current efficiency of the ECP process was 29.9%, which was twice than that of the sequential processes. The enhancement factor was calculated to be 1.63, demonstrating the substantial significant synergistic effects for ECP. Only low MW components could be observed for the EC-E-peroxone (average MW = 533 Da with PD ≈ 1) and ECP process (MW = 538 Da with PD ≈ 1). These results suggested that EC-E-peroxone and ECP process had much stronger oxidation ability, demonstrating the enhancement of OH production induced by the Al-based coagulants might be responsible for the significant enhancement of COD removal. These results indicated there could be a synergistic effect between EC and ozone in addition to EC and E-peroxone reactions. Compared to the two sequential processes, ECP was a high efficiency and space-saving electrochemical system with simultaneous coagulation and enhanced OH generation by the products of anode and the cathode.

Comparison of the performance of prepared pristine and TiO2 coated UF/NF membranes for two types of oil-in-water emulsion separation.

Polysulfone ultrafiltration (UF) and polypiperazine-amide nanofiltration (NF) membranes were first fabricated by phase inversion and interfacial polymerization, and then modified by the commonly used TiO2 on the membrane surface, respectively. Compared with the pristine UF and NF membranes, pure water flux decreased by 40.66% for modified UF membrane and 12.92% for modified NF membrane, while the contact angle of the modified membranes decreased from 66.5° to 35.3° for UF membrane and from 48.2° to37.7° for NF membrane. However, the membrane modified by TiO2 nanoparticles for both UF and NF membranes exhibited much better anti-fouling and separation performance for two types of oil-in-water emulsions with different droplet size (i.e., prepared oil-in-water emulsion with low salinity and oil produced water in Shengli oilfield, China). It was obvious that water flux of modified UF only slightly decreased and the stable water flux was 2.2 times and 15.6% higher than that of pristine membranes for the prepared oil-in-water emulsion and produced water, respectively. According to the five fouling models for UF, the TiO2 modified UF membrane could alleviate the fouling on membrane surface and greatly increase water flux by reducing the adsorption, deposition, blockage of membrane pores and formation of cake layer for two types of oil-in-water emulsion. For NF, water flux of the modified membrane increased by 66.1% and 22.8% for prepared oil-in-water emulsion and produced water, respectively. TiO2 coating effectively alleviated the oil adhesion and cake layer formation on the membrane surface.

Boosting the performance of quantum Otto heat engines.

To optimize the performance of a heat engine in a finite-time cycle, it is important to understand the finite-time effect of thermodynamic processes. Previously, we have shown that extra work is needed to complete a quantum adiabatic process in finite time, and proved that the extra work follows a C/τ^{2} scaling for long control time τ. There the oscillating part of the extra work is neglected due to the complex energy-level structure of the particular quantum system. However, such oscillation of the extra work cannot be neglected in some quantum systems with simple energy-level structure, e.g., the two-level system or the quantum harmonic oscillator. In this paper, we build the finite-time quantum Otto engine on these simple systems, and find that the oscillating extra work leads to a jagged edge in the constraint relation between the output power and the efficiency. By optimizing the control time of the adiabatic processes, the oscillation in the extra work is utilized to enhance the maximum power and the efficiency. We further design special control schemes with the zero extra work at the specific control time. Compared to the linear control scheme, these special control schemes of the finite-time adiabatic process improve the maximum power and the efficiency of the finite-time Otto engine.

Achieve higher efficiency at maximum power with finite-time quantum Otto cycle.

The optimization of heat engines was intensively explored to achieve higher efficiency while maintaining the output power. However, most investigations were limited to a few finite-time cycles, e.g., the Carnot-like cycle, due to the complexity of the finite-time thermodynamics. In this paper, we propose a class of finite-time engine with quantum Otto cycle, and demonstrate a higher achievable efficiency at maximum power. The current model can be widely utilized, benefitting from the general C/τ^{2} scaling of extra work for a finite-time adiabatic process with long control time τ. We apply the adiabatic perturbation method to the quantum piston model and calculate the efficiency at maximum power, which is validated with an exact solution.

Enhanced organic removal for shale gas fracturing flowback water by electrocoagulation and simultaneous electro-peroxone process.

Colloids and organics in shale gas fracturing flowback water (SGFFW) during shale gas extraction are of primary concerns. Coagulation combined with oxidation might be a promising process for SGFFW treatment. In this study, a novel electrocoagulation-peroxone (ECP) process was developed for SGFFW treatment by simultaneous coagulation and oxidation process with a Al plate as the anode and a carbon-PTFE gas diffusion electrode as the cathode, realizing the simultaneous processes of coagulation, H2O2 generation and activation by O3 at the cathode. Compared with electrocoagulation (EC) and peroxi-electrocoagulation (PEC), COD removal efficiency mainly followed the declining order of ECP, PEC and EC under the optimal current density of 50 mA cm-2. The appearance of medium MW fraction (1919 Da) during ozonation and PEC but disappearance in ECP indicated that these intermediate products couldn't be degraded by ozonation and PEC but could be further oxidized and mineralized by the hydroxyl radical produced by the cathode in ECP, demonstrating the hydroxyl radical might be responsible for the significant enhancement of COD removal. The pseudo-first order kinetic model can well fit ozonation and EC process but not the PEC and ECP process due to the synthetic effect of coagulation and oxidation. However, the proposed mechanism based model can generally fit ECP satisfactorily. The average current efficiency for PEC was 35.4% and 12% higher than that of ozonation and EC, respectively. This study demonstrated the feasibility of establishing a high efficiency and space-saving electrochemical system with integrated anodic coagulation and cathodic electro-peroxone for SGFFW treatment.

The role of solubility on the rejection of trace organics by nanofiltration membrane: exemplified with disinfection by-products.

Interactions of trace organic compounds (TOrCs) with polymeric nanofiltration (NF) membrane can affect their rejection. It is desirable to investigate whether solubility which depends on the free energy of interaction between these solutes and water correlates with rejection/adsorption and the potential to be incorporated in the partitioning terms of current NF model. A total of ten neutral disinfection by-products (DBPs) were selected as the model compounds for TOrCs to comprehensively investigate the role of solubility on rejection and adsorption. Pearson correlation analysis indicated that the correlation between MW and rejection ratio was highly significant (r = 0.778, p = 0.008) and that between solubility and rejection ratio was moderately significant (r = -0.636, p = 0.48) in a cross-flow system. By fitting Freundlich equation from adsorption isotherm experiment, the adsorption affinity (K f) of DBPs was roughly correlated with their solubility with regard to the comparison of n value with 1. α was then introduced as a parameter of solute-membrane interaction from the perspective of partitioning term in the hydrodynamic model. Exponential relationship can be observed between the solubility and α, demonstrating the possibility of incorporating solubility into the partitioning terms in NF model to accurately predict the rejection of DBPs.

Immunosuppressive effect of zhankuic acid C from Taiwanofungus camphoratus on dendritic cell activation and the contact hypersensitivity response.

Some ergostane triterpenoids from Taiwanofungus camphoratus have been shown to exhibit anti-inflammatory activity in vitro. However, the effect of ergostane triterpenoids on the immune response remains unknown. In this study, we elucidated that ergostane triterpenoids significantly decreased the cytokines and chemokine release by dendritic cells (DC) and that, in the case of zhankuic acid C (ZAC), the decrease was dose-dependent and inhibited DC maturation. ZAC inhibited the contact hypersensitivity response and infiltrative T cells in the ears of DNFB-stimulated mice. Thus, we demonstrate for the first time that ZAC exhibits an immunosuppressive effect on DC activation and the contact hypersensitivity response. It is suggested that ZAC can potentially be used for treating chronic inflammation and autoimmune diseases.