Long-term operation optimization of circulating cooling water systems under fouling conditions

Fouling caused by excess metal ions in hard water can negatively impact the performance of the circulating cooling water system(CCWS)by depositing ions on the heat exchanger's surface.Currently,the operation optimization of CCWS often prioritizes short-term flow velocity optimization for minimizing power consumption,without considering fouling.However,low flow velocity promotes fouling.Therefore,it's crucial to balance fouling and energy/water conservation for optimal CCWS long-term operation.This study proposes a mixed-integer nonlinear programming(MINLP)model to achieve this goal.The model considers fouling in the pipeline,dynamic concentration cycle,and variable frequency drive to optimize the synergy between heat transfer,pressure drop,and fouling.By optimizing the concentration cycle of the CCWS,water conservation and fouling control can be achieved.The model can obtain the optimal operating parameters for different operation intervals,including the number of pumps,frequency,and valve local resistance coefficient.Sensitivity experiments on cycle and environmental temperature reveal that as the cycle increases,the marginal benefits of energy/water conservation decrease.In periods with minimal impact on fouling rate,energy/water conservation can be achieved by increasing the cycle while maintaining a low fouling rate.Overall,the proposed model has significant energy/water saving effects and can comprehensively optimize the CCWS through its incorporation of fouling and cycle optimization.

Experimental study on the effect of H_(2)O and O_(2) on the degradation of SF_(6) by pulsed dielectric barrier discharge

SF_(6) has excellent insulation performance and arc extinguishing ability,and is widely used in the power industry.However,its global warming potential is about 23,500 times that of C0_(2),it can exist stably in the atmosphere,it is not easily degradable and is of great potential harm to the environment.Based on pulsed dielectric barrier discharge plasma technology,the effects of H_(2)O and 0_(2) on the degradation of SF_(6) were studied.Studies have shown that H_(2)O can effectively promote the decomposition of SF_(6) and improve its degradation rate and energy efficiency of degradation.Under the action of a pulse input voltage and input frequency of 15 kV and 15 kHz,respectively,when H_(2)O is added alone the effect of 1% H_(2)O is the best,and the rate and energy efficiency of degradation of SF_(6) reach their maximum values,which are 91.9% and 8.25 g kWh^(-1),respectively.The synergistic effect of H_(2)O and O_(2) on the degradation of SF_(6) was similar to that of H_(2)O.When the concentration of H_(2)O and O_(2) was 1%,the system obtained the best rate and energy efficiency of degradation,namely 89.7% and 8.05 g kWh~(-1),respectively.At the same time,different external gases exhibit different capabilities to regulate decomposition products.The addition of H_(2)O can effectively improve the selectivity of S0_(2).Under the synergistic effect of H_(2)O and O_(2),with increase in O_(2) concentration the degradation products gradually transformed into SO_(2)F_(2).From the perspective of harmless treatment of the degradation products of SF_(6),the addition of O_(2) during the SF_(6) degradation process should be avoided.

城市地摊经济热潮下的环境问题研究——以南京市为例

发展“地摊经济”是契合中央提出的“稳就业、扩内需”的发展方针,为城市低收入群体拓宽谋生空间,但也给城市绿色发展和节能减排带来了诸多挑战。本文以南京市为例,运用扎根理论等研究方法,从地摊规模与分布、环卫资源配置与管理、环卫工作强度与效率、市民参与与意识四个方面进行分析。针对地摊经济存在的相关法制不健全、监管手段不足、环卫环境不友好、参与主体责任不明确、环保意识不足这五个方面的问题,本文明晰了地摊经济对城市节能减排的影响机理,并提出加强参与主体间的沟通合作、加大环卫执法力度并强化责任追究机制、加强地摊经济环卫建设、推广环保技术产品、提升环保意识和文化水平等五个方面的对策建议,以优化城市地摊经济环卫状况,实现地摊经济与节能减排和生态环境保护的协同发展。

Effects of water stress on quality and sugar metabolism in'Gala'apple fruit

Sugar plays an important role in apple fruit development,appearance and quality as well as contributing to a plant’s water stress response.Trehalose and the trehalose biosynthetic metabolic pathways are part of the sugar signaling system in plants,which are important regulator of water stress response in apple.The effect of water stress treatments applied to apple trees and the corresponding effects of ABA on developmental fruit quality were examined for indicators of fruit quality during fruit development.The results indicated that the severe water stress treatment(W2)occurring after the last stage of fruit cell division caused a decrease in the color and size of fruit.The moderate water stress(W1)occurring after the last stage of fruit cell enlargement(S2)caused an increase in the content of fructose and sorbitol while the apple fruit shape was not affected.These changes in sugar are related to the activity of sugar metabolic enzymes.While the enzymatic activity of vacuolar acid invertase(vAINV)was higher,that of sucrose-phosphate synthase(SPS)was lower in water stress treated fruit throughout the developmental period.This indicates that enhanced sucrose degradation and reduced sucrose synthesis leads to an overall reduced sucrose content during times of drought.Thus,water stress reduced sucrose content.Whereas the content of endogenous trehalose and ABA were the highest in water stress treated fruit.A moderate water stress(W1)imposed on apple trees via water restriction(60%–65%of field capacity)after the fruit cell enlargement phase of fruit development yielded sweeter fruit of higher economic value.

Biosynthesis and Immunological Evaluation of a Dual-Antigen Nanoconjugate Vaccine Against Brucella melitensis

Brucellosis,caused by Brucella,is one of the most common zoonosis.However,there is still no vaccine for human use.Although some live attenuated vaccines have been approved for animals,the protection effect is not ideal.In this study,we developed a dual-antigen nanoconjugate vaccine containing both polysaccharide and protein antigens against Brucella.First,the antigenic polysaccharide was covalently coupled to the outer membrane protein Omp19 using protein glycan coupling technology,and then it was successfully loaded on a nano-carrier through the SpyTag/SpyCatcher system.After confirming the efficient immune activation and safety performance of the dual-antigen nanoconjugate vaccine,the potent serum antibody response against the two antigens and remarkable protective effect in non-lethal and lethal Brucella infection models were further demonstrated through different routes of administration.These results indicated that the dual-antigen nanoconjugate vaccine enhanced both T helper 1 cell(Th1)and Th2 immune responses and protected mice from Brucella infection.Furthermore,we found that this protective effect was maintained for at least 18 weeks.To our knowledge,this is the first Brucella vaccine bearing diverse antigens,including a protein and polysaccharide,on a single nanoparticle.Thus,we also present an attractive technology for co-delivery of different types of antigens using a strategy applicable to other vaccines against infectious diseases.

A self-healing and conductive ionic hydrogel based on polysaccharides for flexible sensors

In this study,we proposed a self-healing conductive hydrogel based on polysaccharides and Li+to serve as flexible sensors.At first,the oxidized sodium alginate(OSA)was obtained through the oxidation reaction of sodium alginate(SA).Then OSA,carboxymethyl chitosan(CMC),and agarose(AGO)were dissolved in LiCl solution,respectively.Finally,the hydrogel was obtained through heating,mixing,and cooling processes.Because of the Schiff base structure and hydrogen bonding,the hydrogel demonstrates good mechanical and self-healing properties.The presence of Li+provides good conductivity for the hydrogel.In addition,we demonstrated the application of the hydrogel as the flexible sensors.It can perceive the process of pressing Morse code with the index finger as a pressure sensor and monitor sliding movement of the thumb as the strain sensor to browse the web with the mobile phone.Thus,the selfhealing conductive hydrogel may have potential applications in flexible wearable sensors.

Recent progress in self-repairing coatings for corrosion protection on magnesium alloys and perspective of porous solids as novel carrier and barrier

Featuring low density and high specific strength, magnesium(Mg) alloys have attracted wide interests in the fields of portable devices and automotive industry. However, the active chemical and electrochemical properties make them susceptible to corrosion in humid, seawater, soil,and chemical medium. Various strategies have revealed certain merits of protecting Mg alloys. Therein, engineering self-repairing coatings is considered as an effective strategy, because they can enable the timely repair for damaged areas, which brings about long-term protection for Mg alloys. In this review, self-repairing coatings on Mg alloys are summarized from two aspects, namely shape restoring coatings and function restoring coatings. Shape restoring coatings benefit for swelling, shrinking, or reassociating reversible chemical bonds to return to the original state and morphology when coatings broken;function self-repairing coatings depend on the release of inhibitors to generate new passive layers on the damaged areas. With the advancement of coating research and to fulfill the demanding requirements of applications, it is an inevitable trend to develop coatings that can integrate multiple functions(such as stimulus response, self-repairing, corrosion warning,and so on). As a novel carrier and barrier, porous solids, especially covalent organic frameworks(COFs), have been respected as the future development of self-repairing coatings on Mg alloys, due to their unique, diverse structures and adjustable functions.

Local density of optical states calculated by the mode spectrum in stratified media

The local density of optical states(LDOS)is an important physical concept,which can characterize the spontaneous emission of microcavities.In order to calculate the LDOS,the relationship between the mode spectrum and the LDOS is established.Then,based on the transfer matrix method and the effective resonator model,the leaky loss of the leaky mode and the mode spectrum in the one-dimensional photonic bandgap crystal waveguide are calculated,results of which indicate that the mode spectrum can characterize the leaky loss of the leaky mode.At last,the density of optical states(DOS),and the LDOS in each layer are calculated.The partial DOS and the partial LDOS in the quantum well,related to the fundamental leaky mode,can be used to find out the optimal location of the quantum well in the defect layer to couple more useful photons into the lasing mode for lasers.

Application Value of High-Frequency Ultrasound and Contrast-Enhanced Ultrasound in Patients with Knee Osteoarthritis with Different TCM Syndromes

Objective: To explore the application value of high-frequency ultrasound and contrast-enhanced ultrasound in different syndrome types of knee osteoarthritis, and to provide more imaging evidence for clinical diagnosis and treatment. Method: Sixty patients with KOA were selected according to TCM classification, which were mainly divided into Qi stagnation and blood stasis type and cold-dampness blockage type. All knee joints were routinely examined by high frequency ultrasound, and those with synovial hyperplasia were examined by contrast-enhanced ultrasound. High frequency ultrasound is the examination of synovium, cartilage and collateral ligament of knee joint based on two-dimensional ultrasound. Contrast-enhanced ultrasound (CEUS) refers to the contrast examination of synovium in knee joint patients with synovial hyperplasia. Result: Among them, the suprapatellar sac effusion and synovial thickening of Qi stagnation and blood stasis type were more obvious than those of cold-dampness arthralgia type (P < 0.05), and the degree of wear of the intercondylar cartilage of cold-dampness arthralgia type was more obvious than that of Qi stagnation. The blood stasis type is heavier and the meniscus bulge is higher (P < 0.05). The radiography of synovial hyperplasia showed that the area under the curve of Qi stagnation and blood stasis type was higher than that of cold dampness arthralgia type (P < 0.05), and the peak time was significantly shorter than that of cold dampness arthralgia type. There was no statistical difference in effective peak gradient and onset time of type (P > 0.05). Conclusion: To a certain extent, the high-frequency ultrasound and contrast-enhanced ultrasound performance of knee osteoarthritis can be used as a dialectical reference for different TCM syndrome types.

Contrastive Analysis of Distractions to Pilot Caused by Various Flight Instrument Displays

Automation of aircraft instrument displays enhances flight safety, but it also increases complexity and pilot workload. Executing changes in flight plan, navigation or communication during flight using flight instrument switches often increases pilots’ workload and this may also cause distraction that adds potential risks to flight safety. This study compares the conventional avionics panel and touchscreen avionic panel to find out the least distractive panel for the pilots. Thirty simulated flights using four different pilots were carried out;and aircraft speed, altitude and heading parameters using both avionics systems were observed to study the operational efficiency and pilot distraction resulted from each of the avionic systems. The distraction was examined by a parameter analysis based on the Mean Squared Error (MSE) mathematical model and visually by recording videos of each simulated flight. The results indicate that the touchscreen system is more efficient and less erroneous for the aircraft in maintaining the parameters as compared with the conventional system. There is also a clear relationship between task completion time and disruption level on the parameters control.

Scientific and Engineering Progress in CO_2 Minerali zation Using Industrial Waste and Natural Minerals

The issues of reducing CO_2 levels in the atmo-sphere, sustainably utilizing natural mineral resources,and dealing with indus trial waste offer challenging opportunities for sustainable development in energy and the environment. The latest advances in CO_2 mineralization technology involving natural minerals and industrial waste are summarized in this paper, with great emphasis on the advancement of fundamental science, economic evaluation, and engineering applications. We discuss several lead-ing large-scale CO_2 mineralization methodologies from a techn ical and engineering-science perspective. For each technology option, we give an overview of the technical parameters, reaction pathway, reactivity, procedural scheme, and laboratorial and pilot devices. Furthermore, we present a discussion of each technology based on experimental results and the literature. Finally, current gaps in knowledge are identified in the conclusion, and an overview of the challenges and opportunities for future research in this field is provided.

Remarkable carbon dioxide catalytic capture (CDCC) leading to solid-form carbon material via a new CVD integrated process (CVD-IP): An alternative route for CO_2 sequestration

Through our newly-developed ＂chemical vapor deposition integrated process （ISVD-IP）＇＂ using carbon OlOXlae （t..u2） as me raw matenal and only carbon source introduced, CO2 could be catalytically activated and converted to a new solid-form product, i.e., carbon nanotubes （CO2-derived） at a quite high yield （the single-pass carbon yield in the solid-form carbon-product produced from CO2 catalytic capture and conversion was more than 30% at a single-pass carbon-base）. For comparison, when only pure carbon dioxide was introduced using the conventional CVD method without integrated process, no solid-form carbon-material product could be formed. In the addition of saturated steam at room temperature in the feed for CVD, there were much more end-opening carbon nano-tubes produced, at a slightly higher carbon yield. These inspiring works opened a remarkable and alternative new approach for carbon dioxide catalytic capture to solid-form product, comparing with that of CO2 sequestration （CCS） or CO2 mineralization （solidification）, etc. As a result, there was much less body volume and almost no greenhouse effect for this solid-form carbon-material than those of primitive carbon dioxide.

Optimization of circulating cooling water systems based on chance constrained programming

Recent research on deterministic methods for circulating cooling water systems optimization has been well developed. However, the actual operating conditions of the system are mostly variable, so the system obtained under deterministic conditions may not be stable and economical. This paper studies the optimization of circulating cooling water systems under uncertain circumstance. To improve the reliability of the system and reduce the water and energy consumption, the influence of different uncertain parameters is taken into consideration. The chance constrained programming method is used to build a model under uncertain conditions, where the confidence level indicates the degree of constraint violation. Probability distribution functions are used to describe the form of uncertain parameters. The objective is to minimize the total cost and obtain the optimal cooling network configuration simultaneously.An algorithm based on Monte Carlo method is proposed, and GAMS software is used to solve the mixed integer nonlinear programming model. A case is optimized to verify the validity of the model. Compared with the deterministic optimization method, the results show that when considering the different types of uncertain parameters, a system with better economy and reliability can be obtained(total cost can be reduced at least 2%).

Research progress in hepatitis B virus covalently closed circular DNA

Hepatitis B virus(HBV)infections are a global public health issue.HBV covalently closed circular DNA(cccDNA),the template for the transcription of viral RNAs,is a key factor in the HBV replication cycle.Notably,many host factors involved in HBV cccDNA epigenetic modulation promote the development of hepatocellular carcinoma(HCC).The HBV cccDNA minichromosome is a clinical obstacle that cannot be efficiently eliminated.In this review,we provide an update on the advances in research on HBV cccDNA and further discuss factors affecting the modulation of HBV cccDNA.Hepatitis B virus X protein(HBx)contributes to HBV cccDNA transcription and the development of hepatocarcinogenesis through modulating host epigenetic regulatory factors,thus linking the cccDNA to hepatocarcinogenesis.The measurable serological biomarkers of continued transcription of cccDNA,the effects of anti-HBV drugs on cccDNA,and potential therapeutic strategies targeting cccDNA are discussed in detail.Thus,this review describes new insights into HBV cccDNA mechanisms and therapeutic strategies for cleaning cccDNA,which will benefit patients with liver diseases.

Comparision of China's volatile organic compound pollution management:a computable general equilibrium approach

The public health and ecological impacts of volatile organic compound(VOCs) pollution have become a serious problem in China,arousing increasing attention to emissions control.In this context,this paper analyses the effectiveness of VOC reduction policies,namely pollution charges and environmental taxes at the national and industrial sector levels.It uses a computable general equilibrium model,which connects macroeconomic variables with VOC emissions inventory,to simulate the effects of policy scenarios(with 2007 as the reference year).This paper shows that VOC emissions are reduced by 2.2% when a pollution charge equal to the average cost of engineering reduction methods-the traditional approach to regulation in China-is applied.In order to achieve a similar reduction,an 8.9% indirect tax would have to be imposed.It concludes that an environmental tax should be the preferred method of VOC regulation due to its smaller footprint on the macroeconomy.Other policies,such as subsidies,should be used as supplements.

A heuristic approach for petrochemical plant layout considering steam pipeline length

Plant layout design affects both investment and performance of a factory. To maximize the economic benefits of a petrochemical factory, a large number of factors must be considered simultaneously, such as material flow, heat flow and safety. However, conventional principles for plant layout design and optimization do not involve the heat flow, resulting in higher construction investment. To solve this problem, a new heuristic approach is proposed in this paper based on the current layout design principles. Both material flow(pipelines for process streams) and heat flow(pipelines for steam) are considered. Three optimization methods with different objective functions are used to optimize the layout. The application of proposed approach is illustrated with a case study. The optimal scheme and pipeline networks can be obtained, and the pipeline length is reduced significantly.

Modeling of fast charging station equipped with energy storage

The popularization of EVs(electric vehicles) has brought an increasingly heavy burden to the development of charging facilities. To meet the demand of rapid energy supply during the driving period, it is necessary to establish a fast charging station in public area. However, EVs arrive at the charging station randomly and connect to the distribution network for fast charging, it causes the grid power to fluctuate greatly and the peak-valley loads to alternate frequently, which is harmful to the stability of distribution network. In order to reduce the power fluctuation of random charging, the energy storage is used for fast charging stations. The queuing model is determined to demonstrate the load characteristics of fast charging station, and the state space of fast charging station system is described by Markov chain. After that the power of grid and energy storage is quantified as the number of charging pile, and each type of power is configured rationally to establish the random charging model of energy storage fast charging station. Finally, the economic benefit is analyzed according to the queuing theory to verify the feasibility of the model.

Mapping the kinetics of hydrogen evolution reaction on Ag via pseudo-single-crystal scanning electrochemical cell microscopy

Elucidating the structure-activity relationship in electrocatalysis is of fundamental interest for electrochemical energy conversion and storage.However,the heterogeneity in the surface structure of electrocatalysts,including the presence of various facets,poses an analytical challenge in revealing the true structure-activity relationship because the activity is conventionally measured on ensemble,resulting in an averaged activity that cannot be unequivocally associated with a single structural motif.Scanning electrochemical cell microscopy(SECCM)[1]combined with colocalized electron backscatter diffraction(EBSD)offers a direct way to reveal the correlative local electrochemical and structural information.Herein,we measured the hydrogen evolution reaction(HER)activity on Ag and its dependence on the crystal orientation.From the combined EBSD and SECCM mapping,it is found that Ag grains closer to{111}show a higher exchange current density,while those closer to{110}show a lower Tafel slope.The Tafel slope is also found to decrease with the step density increase.The ability to measure the electrocatalytic activity under a high mass-transfer rate allows us to reveal the activity difference at a high current density(up to 200 mA/cm^(2)).The approach reported here can be expanded to other systems to reveal the nature of active sites of electrocatalysis.

Modification of short-range repulsive interactions in ReaxFF reactive force field for Fe–Ni–Al alloy

The short-range repulsive interactions of any force field must be modified to be applicable for high energy atomic collisions because of extremely far from equilibrium state when used in molecular dynamics(MD)simulations.In this work,the short-range repulsive interaction of a reactive force field(ReaxFF),describing Fe-Ni-Al alloy system,is well modified by adding a tabulated function form based on Ziegler-Biersack-Littmark(ZBL)potential.The modified interaction covers three ranges,including short range,smooth range,and primordial range.The short range is totally predominated by ZBL potential.The primordial range means the interactions in this range is the as-is ReaxFF with no changes.The smooth range links the short-range ZBL and primordial-range ReaxFF potentials with a taper function.Both energies and forces are guaranteed to be continuous,and qualified to the consistent requirement in LAMMPS.This modified force field is applicable for simulations of energetic particle bombardments and reproducing point defects'booming and recombination effectively.

A game theory based method for inter-plant heat integration considering cost allocation

Inter-plant heat integration is an effective way for energy recovery in process industry. Although inter-plant heat integration can significantly reduce energy consumption, it is not widely applied in the multiple stakeholders’ situation due to profit or cost distribution problems. Therefore, this work considers both the technique aspects of heat integration and its business aspects between stakeholders simultaneously. The new proposed methodology consists of three steps. Firstly the optimal matching of heat integration between plants is obtained through mathematical programming. Then the cost distribution is decided through game theory. Finally the cost distribution obtained previous is corrected by an ideal expert model. A case study is used to illustrate the effectiveness of the method in the end of the work.