Prediction of discharge in a tidal river using the LSTM-based sequence-to-sequence models

The complexity of river-tide interaction poses a significant challenge in predicting discharge in tidal rivers.Long short-term memory(LSTM)networks excel in processing and predicting crucial events with extended intervals and time delays in time series data.Additionally,the sequence-to-sequence(Seq2Seq)model,known for handling temporal relationships,adapting to variable-length sequences,effectively capturing historical information,and accommodating various influencing factors,emerges as a robust and flexible tool in discharge forecasting.In this study,we introduce the application of LSTM-based Seq2Seq models for the first time in forecasting the discharge of a tidal reach of the Changjiang River(Yangtze River)Estuary.This study focuses on discharge forecasting using three key input characteristics:flow velocity,water level,and discharge,which means the structure of multiple input and single output is adopted.The experiment used the discharge data of the whole year of 2020,of which the first 80%is used as the training set,and the last 20%is used as the test set.This means that the data covers different tidal cycles,which helps to test the forecasting effect of different models in different tidal cycles and different runoff.The experimental results indicate that the proposed models demonstrate advantages in long-term,mid-term,and short-term discharge forecasting.The Seq2Seq models improved by 6%-60%and 5%-20%of the relative standard deviation compared to the harmonic analysis models and improved back propagation neural network models in discharge prediction,respectively.In addition,the relative accuracy of the Seq2Seq model is 1%to 3%higher than that of the LSTM model.Analytical assessment of the prediction errors shows that the Seq2Seq models are insensitive to the forecast lead time and they can capture characteristic values such as maximum flood tide flow and maximum ebb tide flow in the tidal cycle well.This indicates the significance of the Seq2Seq models.

Vertical structure of tidal currents in the Xuliujing Section of Changjiang River Estuary

Three long-term fixed acoustic Doppler current profilers were first used for investigating the vertical structure of tidal currents in Xuliujing Section of Changjiang River Estuary.Moreover,three different periods(spring,summer and fall)were also considered for investigating seasonal variations.The semi-diurnal tides were the most energetic,with along-channel speed of up to 80 cm/s for M_(2)constituent,which dominates at all stations with percent energy up to 65%–75%during seasons.The shape of tidal ellipses of the most energetic semi-diurnal constituent M_(2)showed obvious polarization of the flow paralleling to the riverbank,with the minor semi-axis being generally less than 20%of the major one.The maximum velocity of mean current is appeared in top layers at all the three stations,and the velocity decreased with the depth.The seasonal variations of direction are also observed,which is probably caused by complex local topography since the erosion and deposition in riverbed.Observed vertical variation of four parameters of M_(2)ellipses,agreed well with the optimally fit frictional solutions in top and middle layers.However,there was an obvious difference between frictional model and observed data in the lower water column.Discrepancies are probably on account of stratification,which strengthens in summer and fall due to the freshening influence of the Changjiang River Estuary outflow.

Enhanced hydrodeoxygenation of lignin-derived anisole to arenes catalyzed by Mn-doped Cu/Al_(2)O_(3)

Lignin is a renewable carbon resource to produce arenes due to its abundant aromatic structures.For the liquid-phase hydrodeoxygenation(HDO)based on metallic catalysts,the preservation of aromatic rings in lignin or its derivatives remains a challenge.Herein,we synthesized Mndoped Cu/Al_(2)O_(3) catalysts from layered double hydroxides(LDHs)for liquid-phase HDO of lignin-derived anisole.Mn doping significantly enhanced the selective deoxygenation of anisole to arenes and inhibited the saturated hydrogenation on Cu/Al_(2)O_(3).With Mn doping increasing,the surface of Cu particles was modified with MnO_(x) along with enhanced generation of oxygen vacancies(Ov).The evolution of active sites structure led to a controllable adsorption geometry of anisole,which was beneficial for increasing arenes selectivity.As a result,the arenes selectivity obtained on 4Cu/8Mn4AlO_(x) was increased to be more than 6 folds of that value on 4Cu/4Al_(2)O_(3) over the synergistic sites between metal Cu and Ov generated on MnO_(x).

Electrocarboxylation of CO_(2) with Organic Substrates:Toward Cathodic Reaction

Electrocarboxylation of carbon dioxide(CO_(2))using organic substrates has emerged as a promising method for the sustainable synthesis of value-added carboxylic acids due to its renewable energy source and mild reaction conditions.The reactivity and product selectivity of electrocarboxylation are highly dependent on the cathodic behavior,involving a sequence of electron transfers and chemical reactions.Hence,it is necessary to understand the cathodic reaction mechanisms for optimizing reaction performance and product distribution.In this work,a review of recent advancements in the electrocarboxylation of CO_(2)with organic substrates based on different cathodic reaction pathways is presented to provide a reference for the development of novel methodologies of CO_(2)electrocarboxylation.Herein,cathodic reactions are particularly classified into two categories based on the initial electron carriers(i.e.,CO_(2)radical anion and substrate radical anion).Furthermore,three cathodic pathways(ENE(N),ENED,and EDEN)of substrate radical anion-induced electrocarboxylation are discussed,which differ in their electron transfer sequence,substrate dissociation,and nucleophilic reaction,to highlight their implications on reactivity and product selectivity.

政府发展和管理普惠性民办幼儿园的现状及其改进建议

以自编问卷为主要研究工具,采用问卷调查和访谈相结合的方法,本研究以我国中部三省的240所普惠性民办幼儿园为研究样本,对当前地方政府发展普惠性民办幼儿园的现状展开调研,结果显示幼儿园结构性质量是政府认定与评估普惠性民办幼儿园时关注的重点;政府对普惠性民办幼儿园的财政补贴少、方式单一,且政府缺乏对补贴经费使用的监管;政府提供的外部支持与普惠性民办幼儿园的实际需要和利益诉求存在一定差距,其中在专业发展方面提供的环境和条件支持明显不足;政府在普惠性民办幼儿园评估中处于主导地位,忽视幼儿园的自我评估;在评估结果反馈中主要由政府向幼儿园单向反馈,幼儿园缺乏话语权。为更好地促进普惠性民办幼儿园的发展,政府应构建省级统一的普惠性民办幼儿园教育质量评估标准,提高过程性质量指标在评估体系中的比例与权重;建立合理的普惠性民办幼儿园成本分担机制,完善对补贴经费的监管;健全促进普惠性民办幼儿园发展的外部支持系统;建立内外结合的评估制度,并构建政府与普惠性民办幼儿园双向互动的评估反馈机制。

Modifying the acidity of H-MOR and its catalytic carbonylation of dimethyl ether

Among the reactions catalyzed by zeolites there are some that exhibit high selectivity due to the spatial confinement effect of the zeolite framework.Tailoring the acidity,particularly the distribution and location of the Bronsted acid sites in the zeolite is effective for making it a better catalyst for these reactions.We prepared a series of H-mordenite（H-MOR） samples by varying the composition of the sol-gel,using different structure directing agents and post-treatment.NH3-TPD and IR characterization of adsorbed pyridine were employed to determine the amount of Bronsted acid sites in the 8-membered ring and 12-membered ring channels.It was shown that controlled synthesis was a promising approach to improve the concentration of Bronsted acid sites in MOR,even with a low Al content.Using an appropriate composition of Si and Al in the sol-gel favored a higher proportion of Bronsted acid sites in the 8-membered ring channels.HMI as a structure-direct agent gave an obvious enrichment of Bronsted acid sites in the 8-membered ring.Carbonylation of dimethyl ether was used as a probe reaction to examine the modification of the acid properties,especially the Bronsted acid sites in the 8-membered ring channels.There was a linear relationship between methyl acetate formation and the number of Bronsted acid sites in the 8-membered ring channels,demonstrating the successful modification of acid properties.Our results provide information for the rational design and modification of zeolites with spatial constraints.

Interface tuning of Cu+/CuO by zirconia for dimethyl oxalate hydrogenation to ethylene glycol over Cu/SiO2 catalyst

An efficient ZrO2-doped Cu/SiO2 catalyst was fabricated through hydrolysis precipitation method(HP)and used to produce ethylene glycol(EG)through dimethyl oxalate(DMO)hydrogenation.The states for zirconia on copper catalyst and roles in DMO hydrogenation were investigated through various characterization tools,including N2 physical adsorption,XRD,H2-TPR,Methyl glycolate-TPD-MS,XPS,XAES as well.Compared with common ammonia evaporation and co-precipitation methods used in catalyst preparation,this HP method is found to effectively suppress the agglomeration and further size growth of copper nanoparticles by enhancing the interactions between copper and zirconia species.More importantly,uniform distribution of ZrO2 dopant is achieved due to the pseudo-homogeneous reactions in the mixing step of catalyst preparation.A proper amount of zirconium dopant helps achieve the desirable proportion of Cu+/(Cu++CuO)for surface copper species,especially promotes the production of Cu+species originated from Cu-ZrO2 species at the interface of copper and zirconia particles.In comparison with Cu+species formed from copper phyllosilicates reduction,the Cu+sites derived from Cu-ZrO2 species show higher adsorption ability of MG,an important intermediate species in ethylene glycol production.These adsorbed MG molecules further react with atomic hydrogen shifted from adjacent metallic copper surface,leading to a higher catalytic behavior.For the EG production via DMO hydrogenation,the turnover frequency(TOF)normalized by CuO species on CuZr/SiO2 catalyst is 1.8 times than that of traditional Cu/SiO2 counterpart.Due to the enhanced synergy effect between Cu+and Cuo active sites,a lower activation energy of ester hydrogenation on this ZrO2-doped Cu/SiO2 catalyst is believed to be responsible for the significant improvement.

Coupling effect of bifunctional ZnCe@SBA-15 catalyst in 1,3-butadiene production from bioethanol

A series of bifunctional Zn Ce@SBA-15 catalysts with different Zn/Ce ratios were prepared by a solid-state grinding strategy and used in the conversion of ethanol to 1,3-butadiene(ETB).For the supported metal oxides,Zn O serves as the active sites for the dehydrogenation of ethanol,and CeO_(2) promotes the aldolcondensation reaction.Based on the results of Py-FTIR and NH_(3)-TPD,it suggests that the yield of 1,3-butadiene is positively correlated with the number of weak Lewis acid sites on the catalyst surface,given their benefit for aldol-condensation reactions.The catalyst with an optimal Zn/Ce ratio of about 1:5 has the highest concentration of weak Lewis acid.Coupling with the Zn O sites,it contributes to a 98.4%conversion of ethanol and a 45.2%selective of 1,3-butadiene under relatively mild reaction conditions(375°C,101.325 k Pa,and 0.54 h^(-1)).

High-temperature CO_(2) sorbents with citrate and stearate intercalated Ca-Al hydrotalcite-like as precursor

CO_(2),one of the main components of greenhouse gases,increased rapidly because of the growing use of fossil fuels.And CaO sorbents possess the capability to be used in capture of CO_(2) at high temperature.In the work,Ca-Al complex oxides derived from citrate and stearate intercalated layered double hydroxides were fabricated and their CO_(2) adsorption capacity was compared with that from CO_(3)^(2-)intercalated layered double hydroxides.The results presented that the sorbents(Ca/Al=5)with Ca-Al-citrate layered double hydroxides as precursors performed best and displayed remarkable CO_(2) capture capacity of 52.0%(mass)at the carbonization temperature of 600℃without distinct recession during cycling adsorption/desorption tests.The excellent CO_(2) adsorption capacity of the sorbent was ascribed to its smaller crystallite size of calcinated particles,optimized pore size distribution as well as homogeneous distributed Ca and Al in the sorbent.

Bidirectional catalysis of Co_(0.4)Ni_(1.6)P for Li_(2)S_(1-2) deposition/decomposition reactions in Li-S batteries

To improve the electrochemical activity of S electrodes in Li-S batteries,the synergistic electrocatalysis mechanism of Co_(0.4)Ni_(1.6)P with Ni and Co bimetal interactions is clarified.The alternating crystal structure of Co and Ni regulates the adsorption and decomposition energy of Co_(0.4)Ni_(1.6)P to polysulfides and has the bidirectional catalysis for the Li_(2)S_(1-2)deposition/decomposition process.Co_(0.4)Ni_(1.6)P can promote the breaking of the S-S bond of Li_(2)S_(4) and decrease the decomposition energy barrier of Li_(2)S.This regulation accelerates the discharge/charge reaction between S,polysulfides,and Li_(2)S and improves the kinetics of the S electrodes.The 1st,100^(th),and 200^(th) discharge capacity densities at 0.1 mA cm^(-2) of the S electrodes with a high sulfur loading were 1,405,987.2,and 828.4 m Ah gS^(-1),respectively.The bidirectional catalytic mechanism is a novel idea for improving the electrochemical performance of Li-S batteries.

Regulating electronic environment on alkali metal-doped Cu@NS-SiO_(2) for selective anisole hydrodeoxygenation

Lignin utilization is a potential approach for replacing fossil energy and releasing the environment pressure.Herein,we synthesized a series of novel Cu-based catalysts,Cu@NS-SiO_(2)(NS=nano sphere)and alkali metals(Na,K,Rb,and Cs)doped Cu@NS-SiO_(2),and applied them in hydrodeoxygenation reaction of anisole.High Cu dispersion was presented on all catalysts.The modification of alkali metals on Cu@NS-SiO_(2) significantly enhanced the electron density of Cu sites in the following order:Cs>Rb>K>Na,among which Cs decreased the Cu_(2)p_(3)/2 binding energy most(by 0.7 eV).Moreover,the modification did not substantially affect the geometric structure of Cu species.This regulable electronic environment of Cu sites was crucial for selective deoxygenation and inhibiting the hydrogenation of aromatic rings in anisole,and thus promoted the selectivity of benzene.Compared with Cu@NS-SiO_(2)(~59%),the highest benzene selectivity was obtained on Cs/10Cu@NS-SiO_(2) at~83%.

RuCl_3 anchored onto post-synthetic modification MIL-101(Cr)-NH_2 as heterogeneous catalyst for hydrogenation of CO_2 to formic acid

A series of efficient ruthenium chloride (RuCl_3)-anchored MOF catalysts,such as RuCl_3@MIL-101 (Cr)-Sal,and RuCl_3@MIL-101 (Cr)-DPPB, have been successfully synthesized by post-synthetic modification (PSM)of the terminal amino of MIL-101(Cr)-NH_2 with salicylaldehyde, 2-diphenylphosphinobenzaldehyde (DPPBde) and anchoring of Ru (Ⅲ) ions. The stronger coordination electron donor interaction between Ru (Ⅲ) ions and chelating groups in the RuCl_3@MIL-101 (Cr)-DPPB enhances its catalytic performance for CO_2 hydrogenation to formic acid. The turnover number (TON) of formic acid was up to 831 in reaction time of 2 h with dimethyl sulfoxide (DMSO) and water (H_2O) as mixed solvent, trimethylamine (Et_3N) as organic base, and PPh_3 as electronic additive.

New ZnCe catalyst encapsulated in SBA-15 in the production of 1,3-butadiene from ethanol

ZnO-CeO2/SBA-15 catalysts were prepared by two kinds of solid-state grinding method and used for the production of 1,3-butadiene(1,3-BD) from ethanol.A mixture of SBA-15(with or without organic template) and metal precursors were ground in solid-state.The obtained catalysts were characterized by TG,N2 adsorption-desorption,TEM,XRD,Py-FTIR and NH_3-TPD techniques.Superior dispersion of metal oxides and more exposed acid sites were achieved on the catalyst lOZn_1Ce_5-AS with the presence of organic template in SBA-15 during the solid-state grinding process.The catalytic performance was evaluated in a fixed-bed reactor and a 1,3-butadiene selectivity of as high as 45% is achieved.This is attributed to the coupling effect of Zn and Ce species in the mesopores of SBA-15,in which Zn promotes ethanol dehydrogenation and Ce enhances aldol-condensation,respectively.Additionally,solvent-free method inspires new catalyst synthesis strategy for the production of 1,3-butadiene from ethanol.

Oxycarbonylation of methanol over modified CuY: Enhanced activity by improving accessibility of active sites

CuY zeolite is a promising catalyst in the field of manufacturing dimethyl carbonate(DMC) through oxidative carbonylation of methanol. Cu^+ exchanged with Br?nsted acid sites are supposed to be active for this reaction. However, the location of Cu^+ in small cages can not interact with reactants because of steric hindrance, which lead to a waste of Cu species. In this work, NH_4F solution was used to modify the pore structure of zeolite Y by etching the framework T atoms. Physical and chemical adsorption of probe molecules with different size are used to determine the changes of porosity as well as the accessibility of Cu^+ sites. At an optimized etching time, the small cages were opened with maintained zeolitic framework. As a result, more Cu^+ species located in small cages become accessible to reactants, which contributes to the enhanced activity in this reaction.

Pd-Fe/a-AI203/cordierite monolithic catalysts for the synthesis of dimethyl oxalate： effects of calcination and structure

Cordierite monoliths coated with Pd-Fe/a- Al2O3 catalysts were prepared at various calcination temperatures and characterized by thermogravimetry, temperature-programmed reduction, transmission electron microscopy, diffuse reflectance infrared Fourier transfor- mation spectroscopy and X-ray diffraction. The performance of the catalytic monoliths for the synthesis of dimethyl oxalate （DMO） through a CO coupling reaction was evaluated. Monolithic catalysts with calcination temperatures ranging from 473 K to 673 K exhibited excellent dispersion of Pd, good CO adsorption properties, and excellent performance for the coupling reaction. The optimized monolithic catalyst exhibited a much higher Pd efficiency （denoted as DMO （g）.Pd （g）-1 h 1） （733h-1） than that of the granular catalyst （60.2 h-1）, which can be attributed to its honeycomb structure and the large pore sizes in the a-Al2O3 washcoat which was accompanied with an even distribution of the active component in the coating layer along the monoliths channels.

Effect of thermal pretreatment on the surface structure of PtSn/SiO2 catalyst and its performance in acetic acid hydrogenation

The effect of thermal pretreatment on the active sites and catalytic performances of PtSn/SiO2 catalyst in acetic acid （AcOH） hydrogenation was investigated in this article. The catalysts were characterized by N2 physical adsorption, X-ray diffraction, transmission electron microscopy, pyridine Fourier-transform infrared spectra, and H2-O2 titration on its physicochemical properties. The results showed that Pt species were formed primarily in crystalline structure and no PtSnx alloy was observed. Meanwhile, with the increment of thermal pretreatrnent temperature, Pt dispersion showed a decreas- ing trend due to the aggregation of Pt particles. Simultaneously, the amount of Lewis acid sites was remarkably influenced by such thermal pretreatment owning to the consequent physicochemical property variation of Sn species. Interestingly, the catalytic activity showed the similar variation trend with that of Lewis acid sites, confirming the important roles of Lewis acid sites in AcOH hydrogenation. Moreover, a balancing effect between exposed Pt and Lewis acid sites was obtained, resulting in the superior catalytic performance in AcOH hydrogenation.

Enhanced synergy between Cu^(0) and Cu^(+) on nickel doped copper catalyst for gaseous acetic acid hydrogenation

As the substitution of common noble catalysts in the hydrogenation of carboxylic acid,a highly effective Cu-Ni/SiO_(2) catalyst was prepared by a novel stepwise ammonia evaporation method.Its performance in the gasphase hydrogenation of acetic acid was further examined.With the introduction of Ni dopant,more stable Cu^(δ+) sites,which can adsorb more acetic acid,were formed due to the electron transfer from Cu to Ni.This makes more Cu^(0) sites available for hydrogen adsorption,which was suggested as the rate-determining step in acetic acid hydrogenation.A conversion of 99.6% was successfully achieved on this new Cu/SiO_(2)-0.5Ni catalyst,accompanied by the ethanol selectivity of 90%.The incorporation of nickel between copper nanoparticles enhances the synergistic effect between Cu^(0) and Cu^(+).It also helps mitigate the aggregation of copper nanoparticles due to the Ostwald ripening effect induced by acetic acid and enhance the stability of copper catalyst in the conversion of carboxylic acid.

Proton-induced fast preparation of size-controllable MoS2 nanocatalyst towards highly efficient water electrolysis

MoS2 has emerged for catalyzing the hydrogen evolution reaction.Various notable strategies have been developed to downsize the MoS2 particles and expose more active edges.However,the restacking issue,which reduces the exposure degree,has rarely been taken into account.Herein,we report on a facile proton-induced fast hydrothermal approach to produce size-controllable MoS2 nanocatalysts and demonstrate that along the varying of sheet sizes,there is a trade-off between the intrinsic catalytic activity(mainly determined by the unsaturated sulfur on the sheet edges)and the active edge accessibility(influenced by the assembly structure).The size-optimized catalyst delivers a high performance of a low overpotential of~200 mV at 10 mA/cm^(2),a Tafel slope of 46.3 mV/dec,and a stable working state,which is comparable to the recent notable works.Our findings will provide a pathway for its large-scale application and enhance the water electrolysis performance.

Efficient MgO-doped CaO sorbent pellets for high temperature CO_(2) capture

Novel MgO-doped CaO sorbent pellets were prepared by gel-casting and wet impregnation.The effect of Na^(+) and MgO on the structure and CO_(2) adsorption performance of CaO sorbent pellets was elucidated.MgOdoped CaO sorbent pellets with the diameter range of 0.5-1.5 mm exhibited an excellent capacity for CO_(2) adsorption and adsorption rate due to the homogeneous dispersion of MgO in the sorbent pellets and its effects on the physical structure of sorbents.The results show that MgO can effectively inhibit the sintering of CaO and retain the adsorption capacity of sorbents during multiple adsorption-desorption cycles.The presence of mesopores and macropores resulted in appreciable change of volume from CaO(16.7 cm^(3)·mol^(-1))to CaCO3(36.9 cm^(3)·mol^(-1))over repeated operation cycles.Ca2Mg1 sorbent pellets exhibited favorable CO_(2) capture capacity(9.49 mmol·g^(-1)),average adsorption rate(0.32 mmol·g^(-1)·min^(-1)) and conversion rate of CaO(74.83%) after 30 cycles.

Influence of crystalline phase of Li-AI-O oxides on the activity of Wacker-type catalysts in dimethyl carbonate synthesis

The catalysts supported on LiA1508 （spinel） for vapor phase synthesis of dimethyl carbonate （DMC） from methyl nitrite （MN） have been studied. Their catalytic activities on supports prepared by different methods were evaluated in a continuous reactor. The samples were characterized by powder X-ray diffraction, N2 adsorption-desorption isotherms, fourier transform infrared spectroscopy and temperature-programmed reduction of H2. Li/A1 molar ratio and calcination temperature greatly influence the structure of crystalline phase of Li-AI-O oxides. Desirable LiAIsO8 （spinel） was formed at 800℃, while LiA1508 （primitive cube） formed at 900℃ is undesirable for the reaction. A high Li/A1 molar ratio, which was related with LiA102, also slowed the reaction rate. The electron transfer ability and the interaction with active component are the important properties of the spinel-based supports. The CuC12-PdC12/LiAIsO8 （spinel） with better electron transfer ability and low Pd2＋ reduction temperature exhibited a better catalytic ability.