The quantitative estimation of amikacin （AMK） in AMK sulfate injection samples is reported using FTIR-derivative spectrometric method in a continuous flow system. Fourier transform of mid-IR spectra were recorded wi...The quantitative estimation of amikacin （AMK） in AMK sulfate injection samples is reported using FTIR-derivative spectrometric method in a continuous flow system. Fourier transform of mid-IR spectra were recorded without any sample pretreatment. A good linear calibration （r40.999, %RSDo 2.0） in the range of 7.7-77.0 mg/mL was found. The results showed a good correlation with the manufacturer＇s and overall they all fell within acceptable limits of most pharmacopoeial monographs on AMK sulfate.展开更多
Cutting-edge research has primarily focused on flow synthesis of linear block copolymers,lacking the ability for manipulating chain architectures for more extensive applications.Herein,we develop a flow chemistry plat...Cutting-edge research has primarily focused on flow synthesis of linear block copolymers,lacking the ability for manipulating chain architectures for more extensive applications.Herein,we develop a flow chemistry platform for the continuous microflow synthesis of bottlebrush block copolymers(BBCPs)using a grafting-through method.This involves performing ring-opening metathesis polymerization(ROMP)of two different macromonomers within two microfluidic reactors connected in series.The microflow environment allows for complete monomer conversion within a few tens of seconds,benefiting from the superior mixing efficiency achieved in Z-shaped channels as indicated by both theoretical simulations and experimental results.Consequently,a library of well-defined BBCPs of up to 528 distinct samples can be produced within one day through automation of the continuous procedure,while keeping precise control on degree of polymerization(DP<4)and polydispersity indices(PDI<1.2).The synthetic method is generally applicable to different macromonomers with different compositions and contour lengths,yielding libraries of branched block copolymers with great diversity in physiochemical properties and chain architectures.This work presents a powerful platform for high-throughput production of branched copolymers,significantly lowering the costs of the materials for real applications.展开更多
Erlotinib is an orally administered, highly effective, specific epidermal growth factor receptor tyrosine kinase inhibitor, used to treat non-small cell lung cancer and pancreatic cancer. The traditional synthetic met...Erlotinib is an orally administered, highly effective, specific epidermal growth factor receptor tyrosine kinase inhibitor, used to treat non-small cell lung cancer and pancreatic cancer. The traditional synthetic methods for Erlotinib exhibit long reaction time and safety concern. Herein, we describe a novel five-step route for the synthesis of Erlotinib in flow. These five steps comprise etherification, nitration, reduction,addition and cyclization reactions. All steps were optimized and converted to continuous flow process,which drastically reduces the reaction time and considerably improves the process safety as well as the total yield. Enabled by five continuous flow units, Erlotinib is efficiently afforded with an E-factor of 38,an overall yield of 83%, and a total residence time of 25.1 min. Majority steps in this process have been optimized for quantitative conversion, which offers the possibility of telescoping the entire process.展开更多
The aim of this study is to use a new configuration of porous media in a heat exchanger in continuous hydrothermal flow synthesis(CHFS)system to enhance the heat transfer and minimize the required length of the heat e...The aim of this study is to use a new configuration of porous media in a heat exchanger in continuous hydrothermal flow synthesis(CHFS)system to enhance the heat transfer and minimize the required length of the heat exchanger.For this purpose,numerous numerical simulations are performed to investigate performance of the system with porous media.First,the numerical simulation for the heat exchanger in CHFS system is validated by experimental data.Then,porous media is added to the system and six different thicknesses for the porous media are examined to obtain the optimum thickness,based on the minimum required length of the heat exchanger.Finally,by changing the flow rate and inlet temperature of the product as well as the cooling water flow rate,the minimum required length of the heat exchanger with porous media for various inlet conditions is assessed.The investigations indicate that using porous media with the proper thickness in the heat exchanger increases the cooling rate of the product by almost 40% and reduces the required length of the heat exchanger by approximately 35%.The results also illustrate that the most proper thickness of the porous media is approximately equal to 90% of the product tube's thickness.Results of this study lead to design a porous heat exchanger in CHFS system for various inlet conditions.展开更多
Reductive amination by amine dehydrogenases is a green and sustainable process that produces only water as the by-product.In this study,a continuous flow process was designed utilizing a packed bed reactor filled with...Reductive amination by amine dehydrogenases is a green and sustainable process that produces only water as the by-product.In this study,a continuous flow process was designed utilizing a packed bed reactor filled with co-immobilized amine dehydrogenase wh84 and glucose dehydrogenase for the highly efficient biocatalytic synthesis of chiral amino alcohols.The immobilized amine dehydrogenase wh84 exhibited better thermo-,pH and solvent stability with high activity recovery.(S)-2-aminobutan-1-ol was produced in up to 99%conversion and 99%ee in the continuous flow processes,and the space-time yields were up to 124.5 g L-1 d-1.The continuous reactions were also extended to 48 h affording up to 91.8%average conversions.This study showcased the important potential to sustainable production of chiral amino alcohols in continuous flow processes.展开更多
Triflumezopyrim(TFM)is a novel mesoionic pyrido[1,2-α]pyrimidinones insecticide,which acts on nicotinic acetylcholine receptors(n ACh Rs)and has no cross-resistance with other insecticides.Herein,we firstly developed...Triflumezopyrim(TFM)is a novel mesoionic pyrido[1,2-α]pyrimidinones insecticide,which acts on nicotinic acetylcholine receptors(n ACh Rs)and has no cross-resistance with other insecticides.Herein,we firstly developed a new continuous flow approach to synthesis 2-[3-(trifluoromethyl)phenyl]malonic acid,a key intermate of TFM,coupling with esterification,condensation,and hydrolysis.All three-step reactions were optimized and transformed into a continuous synthesis mode by three micro reaction units.Compared with the batch mode,the total reaction time and overall separation yield were improved from more than 12 h and 60%to 18 min and 73.38%,respectively.The solvent consumption and waste emission were significantly reduced,which also provides an eco-friendly and efficient potential tool for the development and production of mesoionic pyrido[1,2-α]pyrimidinones insecticide.展开更多
The degradation of formaldehyde gas was studied using UV/TiO2/O3 process under the condition of continuous flow mode. The effects of humidity, initial formaldehyde concentration, residence time and ozone adding amount...The degradation of formaldehyde gas was studied using UV/TiO2/O3 process under the condition of continuous flow mode. The effects of humidity, initial formaldehyde concentration, residence time and ozone adding amount on degradation of formaldehyde gas were investigated. The experimental results indicated that the combination of ozonation with photocatalytic oxidation on the degradation of formaldehyde showed a synergetic action, e.g,, it could considerably increase decomposing of formaldehyde. The degradation efficiency of formaldehyde was between 73.6% and 79.4% while the initial concentration in the range of 1.84--24 mg/m^3 by O3/TiO2flJV process. The optimal humidity was about 50% in UV/TiO2/O3 processs and degradation of formaldehyde increases from 39.0% to 94.1% when the ozone content increased from 0 to 141 mg/m^3. Furthermore, the kinetics of formaldehyde degradation reaction could be described by Langmuir-Hinshelwood model. The rate constant k of 46.72 mg/（m^3.min） and Langmuir adsorption coefficient K of 0.0268 m^3/mg were obtained.展开更多
In this study,a modified continuous-flow nitrifying reactor was successfully operated for rapid cultivation of micro-granules and achieving robust nitritation.Results showed that sludge granulation with mean size of c...In this study,a modified continuous-flow nitrifying reactor was successfully operated for rapid cultivation of micro-granules and achieving robust nitritation.Results showed that sludge granulation with mean size of ca.100μm was achieved within three weeks by gradually increasing settling velocity-based selection pressure from 0.48 to 0.9 m/hr.Though Nitrospira like nitrite-oxidizing bacteria(NOB)were enriched in the micro-granules with a ratio between ammonia-oxidizing bacteria(AOB)and NOB of 5.7%/6.5% on day 21,fast nitritation was achieved within one-week by gradually increasing of influent ammonium concentration(from 50 to 200 mg/L).Maintaining ammonium in-excess was the key for repressing NOB in the micro-granules.Interestingly,when the influent ammonium concentration switched back to 50 mg/L still with the residual ammonium of 15–25 mg/L,the nitrite accumulation efficiency increased from 90%to 98%.Experimental results suggested that the NOB repression was intensified by both oxygen and nitrite unavailability in the inner layers of micro-granules.Unexpectedly,continuous operation with ammonium in excess resulted in overproduction of extracellular polysaccharides and overgrowth of some bacteria(e.g.,Nitrosomonas,Arenimonas,and Flavobacterium),which deteriorated the micro-granule stability and drove the micro-granules aggregation into larger ones with irregular morphology.However,efficient nitritation was stably maintained with extremely high ammonium oxidation potential(>50 mg/g VSS/hr)and nearly complete washout of NOB was obtained.This suggested that smooth and spherical granule was not a prerequisite for achieving NOB wash-out and maintaining effective nitritation in the granular reactor.Overall,the microgranules exhibited a great practical potential for high-rate nitritation.展开更多
An online method using continuous flow isotope ratio mass spectrometry （CF-IRMS） interfaced with a Gasbench Ⅱ was presented to determine chlorine stable isotope composition. Silver chloride （AgCl） was quantitativ...An online method using continuous flow isotope ratio mass spectrometry （CF-IRMS） interfaced with a Gasbench Ⅱ was presented to determine chlorine stable isotope composition. Silver chloride （AgCl） was quantitatively derived from chloride by using silver nitrate （AgNO3）, and then was reacted with iodomethane （CH3Ⅰ） to produce methyl chloride （CH3Cl）. A GasBench Ⅱ equipped with a PoraPlot Q column was used to separate CH3Cl from any other gas species. Finally, chlorine stable isotope analysis was carried out on CH3Cl introduced to the IRMS in a helium stream via an active open split. The minimum amount of Cl used in this method is of the order of 1.4 μmol. Inter-laboratory and inter-technique comparisons show that the total uncertainty incorporating both the precision and accuracy of this method is better than 0.007%. Furthermore, ten seawaters sampled from different locations have a narrow δ37Cl value range from -0.008% to 0.010%, with a mean value of （0.000±0.006）%. This supports the assumption that any seawater can be representative of standard mean ocean chloride （SMOC） and used as an international reference material.展开更多
A novel method based on the selective pressure of particle size （particle-size cultivation method, PSCM） was developed for the cultivation and operation of aerobic granular sludge in a continuous-flow reactor, and c...A novel method based on the selective pressure of particle size （particle-size cultivation method, PSCM） was developed for the cultivation and operation of aerobic granular sludge in a continuous-flow reactor, and compared with the conventional method based on the selective pressure of settling velocity （settling-velocity cultivation method, SVCM）. Results indicated that aerobic granules could be cultivated in continuous operation mode by this developed method within 14 days. Although in the granulation process, under particle-size selective pressure, mixed liquor suspended solids （MLSS） in the reactor fluctuated greatly and filamentous bacteria dominated the sludge system during the initial operation days, no obvious difference in profile was found between the aerobic granules cultivated by PSCM and SVCM. Moreover, aerobic granules cultivated by PSCM presented larger diameter, lower water content and higher specific rates of nitrification, denitrifieation and phosphorus removal, but lower settling velocity. Under long term operation of more than 30 days, aerobic granules in the continuous-flow reactor could remain stable and obtain good chemical oxygen demand （COD）, NH4^＋-N, total nitrogen （TN） and total phosphorus （TP） removal. The results indicate that PSCM was dependent on the cultivation and maintenance of the stability of aerobic granules in continuous-flow bioreactors.展开更多
A continuous flow bioreactor was operated for 300 days to investigate partial nitritation(PN)of mature landfill leachate,establishing the long-term performance of the system in terms of the microbial community composi...A continuous flow bioreactor was operated for 300 days to investigate partial nitritation(PN)of mature landfill leachate,establishing the long-term performance of the system in terms of the microbial community composition,evolution,and interactions.The stable operation phase(31-300 d)began after a 30 days of start-up period,reaching an average nitrite accumulation ratio(NAR)of 94.43%and a ratio of nitrite nitrogen to ammonia nitrogen(NO_(2)^(−)-N/NH_(4)^(+)-N)of 1.16.Some fulvic-like and humic-like compounds and proteins were effectively degraded in anaerobic and anoxic tanks,which was consistent with the corresponding abundance of methanogens and syntrophic bacteria in the anaerobic tank,and organic matter degrading bacteria in the anoxic tank.The ammonia-oxidizing bacteria(AOB)Nitrosomonas was found to be the key functional bacteria,exhibiting an increase in abundance from 0.27%to 6.38%,due to its collaborative interactions with organic matter degrading bacteria.In-situ inhibition of nitrite-oxidizing bacteria(NOB)was achieved using a combination of free ammonia(FA)and free nitrous acid(FNA),low dissolved oxygen(DO)with fewer bioavailable organics conditions were employed to maintain stable PN and a specific ratio of NO_(2)^(−)-N/NH_(4)^(+)-N,without an adverse impact on AOB.The synergistic relationships between AOB and both denitrifying bacteria and organic matter degrading bacteria,were found to contribute to the enhanced PN performance and microbial community structure stability.These findings provide a theoretical guidance for the effective application of PN-Anammox for mature landfill leachate treatment.展开更多
The creation of an environmentally friendly synthesis method for silver nanomaterials(Ag-NPs)is an urgent concern for sustainable nanotechnology development.In the present study,a novel straightforward and green metho...The creation of an environmentally friendly synthesis method for silver nanomaterials(Ag-NPs)is an urgent concern for sustainable nanotechnology development.In the present study,a novel straightforward and green method for the preparation of silver nanoparti-cle/reduced graphene oxide(AgNP/rGO)composites was successfully developed through the combination of phytosynthesis,continuous flow synthesis and microwave-assistance.Oriental persimmon(Diospyros kaki Thunb.)extracts were used as both plant reducing and capping agents for fast online synthesis of AgNP/rGO composites.The experimental param-eters were optimized and the morphologies of the prepared materials were investigated.The characterization results reveal that spherical AgNPs were quickly synthesized and uni-formly dispersed on rGO sheets using the proposed online system.Fourier transform in-frared spectroscopy analysis confirmed that phenols,flavonoids,and other substances in the plant extracts played a decisive role in the synthesis of AgNP/rGO composites.Using sodium borohydride(NaBH4)degradation of p-nitrophenol(4-NP)as a model,the catalytic activity of the prepared AgNP/rGO materials was evaluated.The complete degradation of 4-NP was achieved within 12 min through the use of AgNP/rGO materials,and the compos-ite had a much better catalytic activity than the bare AgNPs and rGO had.Compared with the conventional chemical method,our online method is facile,fast,cost-efficient,and en-vironmentally friendly.展开更多
To quickly and accurately estimate the expected work-in-process (WIP)of material intersection points in continuous automated material handling systems (AMHSs) ,a queuing-based performance analytical model was presente...To quickly and accurately estimate the expected work-in-process (WIP)of material intersection points in continuous automated material handling systems (AMHSs) ,a queuing-based performance analytical model was presented for continuous flow transporters (CFTs) . In the modeling procedure which considered layout of crossovers and the variability of service time of turntables, an M /G /1 queuing model with multi-class customers and a non-preemptive priority M /G /1 queuing model with multi-class customers were introduced to accurately present the queuing WIP of each material intersection point and perform the analytical model. Finally,300 mm wafer fabrication facilities (fabs)with 24 bays were applied to evaluating the proposed model. Compared with results of an Arena simulation, the model performs well in evaluating the number of queuing WIP of the intersection points and overall system of CFTs in AMHSs.展开更多
Porous materials play an important role in chemical catalysis,separation and other industrial applications.High-efficiency preparation of porous materials has become an active research area.Conventional synthesis of p...Porous materials play an important role in chemical catalysis,separation and other industrial applications.High-efficiency preparation of porous materials has become an active research area.Conventional synthesis of porous materials has been dominated by one-pot solution processing conditions carried out by bulk mixing under conventional electric heating via hydrothermal,solvothermal or ionothermal reactions where high temperatures and pressures are the standard.Continuous flow synthesis has many key advantages in terms of efficient mass and heat transfer,precise control of residence times,improved opportunities for automation and feedback control of synthesis,scaling-up reactions and improved safety parameters compared to above mentioned conventional batch scale synthetic methods.In this review,continuous flow synthesis of various crystalline porous materials such as metal-organic frameworks(MOFs),covalent-organic frameworks(COFs),porous organic cages and zeolites is discussed.Combination of microfluidic methods with other techniques are also shown including various heating ways and various methods of substrate adding.展开更多
Several methods for analysis of dissolved total phosphorus in seawater were reviewed. Discussions were focused on UVirradiation and persulphate oxidation methods which are the most popular dissolved organic phosphorus...Several methods for analysis of dissolved total phosphorus in seawater were reviewed. Discussions were focused on UVirradiation and persulphate oxidation methods which are the most popular dissolved organic phosphorus determinationmethods presently. The compounds used for the phosphorus recovery test were categorized into three groups accordingto their chemical structure. It was found that low power UV irradiation can decompose POC or PC bonds efficientlybut may be inefficient for POP bonds. Heating-bath in acid condition is useful for decomposing POP bonds. Usingthe continuous flow analysis system (Auto-analyzer II), UV digestion and heating-bath, series experiments were carriedout based on the above analysis. Eleven model compounds were employed for the phosphorus recovery test and thefactors influencing the decomposition efficiency of dissolved compounds containing phosphorus were clarified. Finally,the optimal design for determination of dissolved total phosphorus in seawater based on the routine continuous flowanalysis system was presented. For the organic mono-phosphate, the recovery is more than 90% and a recovery of33%~51% was obtained for inorganic or organic polyphosphates. Up to now, this is the highest decompositionefficiency for dissolved phosphorus based on the continuous flow analysis system.展开更多
Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate ...Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems.展开更多
The metallurgical phenomena occurring in the continuous casting mold have a significant influence on the performance and the quality of steel product.The multiphase flow phenomena of molten steel,steel/slag interface ...The metallurgical phenomena occurring in the continuous casting mold have a significant influence on the performance and the quality of steel product.The multiphase flow phenomena of molten steel,steel/slag interface and gas bubbles in the slab continuous casting mold were described by numerical simulation,and the effect of electromagnetic brake（EMBR） and argon gas blowing on the process were investigated.The relationship between wavy fluctuation height near meniscus and the level fluctuation index F,which reflects the situation of mold flux entrapment,was clarified.Moreover,based on a microsegregation model of solute elements in mushy zone with δ/γ transformation and a thermo-mechanical coupling finite element model of shell solidification,the thermal and mechanical behaviors of solidifying shell including the dynamic distribution laws of air gap and mold flux,temperature and stress of shell in slab continuous casting mold were described.展开更多
The direct hydroxylation of benzene to phenol catalyzed by activated carbon-supported Fe （Fe/AC） in acetonitrile using H2O2 as the oxidant was studied in a continuous flow reactor. Results showed that the continuous...The direct hydroxylation of benzene to phenol catalyzed by activated carbon-supported Fe （Fe/AC） in acetonitrile using H2O2 as the oxidant was studied in a continuous flow reactor. Results showed that the continuous operation could obtain high phenol yield of 28.1%, coupled with the turnover frequency of 3 h^-1, and high selectivity of 98% under mild condition. The catalyst was characterized by N2 adsorption/desorption, Boehm titration, X-ray photoelectron spectra, and Fourier transform infrared spectroscopy. It was observed that iron may interact with the carboxyl group forming iron-carboxylate like species, which act as the active phase. The apparent activation energy obtained by fitting an Arrhenius model to the experimental data was 13.4 kJ/mol. The reaction order was calculated to be about i, 0.2 for benzene and 0.7 for H202.展开更多
Continuous flow intersections (CFIs), also known as displaced left turns (DLTs), are a type of alternative intersection designed to improve operations at locations with heavy left-turn movements by reallocating these ...Continuous flow intersections (CFIs), also known as displaced left turns (DLTs), are a type of alternative intersection designed to improve operations at locations with heavy left-turn movements by reallocating these vehicles to the left side of opposing traffic. Currently, simulation is commonly used to evaluate operational performance of CFIs. However, this approach requires significant on-site data collection and is highly dependent on the analyst’s ability to correctly model the intersection and driver behavior. Recently, connected vehicle (CV) trajectory data has become widely available and presents opportunities for the direct measurement of traffic signal performance measures. This study utilizes CV trajectory data to analyze the performance of a CFI located in West Valley City, UT. Over 4500 trajectories and 105,000 GPS points are analyzed from August 2021 weekday data. Trajectories are linear-referenced to generate Purdue Probe Diagrams (PPDs) and extended PPDs to estimate split failures (SF), arrivals on green (AOG), traditional Highway Capacity Manual (HCM) level of service (LOS), and the distribution of stops. The estimated operational performance showed effective progression during the PM peak period at all the critical internal storage areas with AOG levels at exit traffic signals between 83% and 100%. In contrast, all external approaches with longer queue storage areas had AOG values ranging from 2% to 81% during the same time period. The presented analytical techniques and summary graphics provide practitioners with tools to evaluate the performance of any CFI where CV trajectories are available without the need for on-site data collection.展开更多
In an integrated electricity-gas system(IEGS),load fluctuations affect not only the voltage in the power system but also the gas pressure in the natural gas system.The static voltage stability region(SVSR)method is a ...In an integrated electricity-gas system(IEGS),load fluctuations affect not only the voltage in the power system but also the gas pressure in the natural gas system.The static voltage stability region(SVSR)method is a tool for analyzing the overall static voltage stability in a power system.However,in an IEGS,the SVSR boundary may be overly optimistic because the gas pressure may collapse before the voltage collapses.Thus,the SVSR method cannot be directly applied to an IEGS.In this paper,the concept of the SVSR is extended to the IEGS-static stability region(SSR)while considering voltage and gas pressure.First,criteria for static gas pressure stability in a natural gas system are proposed,based on the static voltage stability criteria in a power system.Then,the IEGS-SSR is defined as a set of active power injections that satisfies multi-energy flow(MEF)equations and static voltage and gas pressure stability constraints in the active power injection space of natural gas-fired generator units(NGUs).To determine the IEGSSSR,a continuation MEF(CMEF)method is employed to trace the boundary point in one specific NGU scheduling direction.A multidimensional hyperplane sampling method is also proposed to sample the NGU scheduling directions evenly.The obtained boundary points are further used to form the IEGSSSR in three-dimensional(3D)space via a Delaunay triangulation hypersurface fitting method.Finally,the numerical results of typical case studies are presented to demonstrate that the proposed method can effectively form the IEGS-SSR,providing a tool for IEGS online monitoring and dispatching.展开更多
基金the CDCHTA of the University of Los Andes for providing financial support through several approved projectsthe National Fund for Science, Technology and Innovation (FONACIT) of Venezuelan Ministry of Science and Technology for providing financial support, SPE 112–370 and Project G-2005000641
文摘The quantitative estimation of amikacin （AMK） in AMK sulfate injection samples is reported using FTIR-derivative spectrometric method in a continuous flow system. Fourier transform of mid-IR spectra were recorded without any sample pretreatment. A good linear calibration （r40.999, %RSDo 2.0） in the range of 7.7-77.0 mg/mL was found. The results showed a good correlation with the manufacturer＇s and overall they all fell within acceptable limits of most pharmacopoeial monographs on AMK sulfate.
基金financially supported by the National Natural Science Foundation of China(No.22071176)。
文摘Cutting-edge research has primarily focused on flow synthesis of linear block copolymers,lacking the ability for manipulating chain architectures for more extensive applications.Herein,we develop a flow chemistry platform for the continuous microflow synthesis of bottlebrush block copolymers(BBCPs)using a grafting-through method.This involves performing ring-opening metathesis polymerization(ROMP)of two different macromonomers within two microfluidic reactors connected in series.The microflow environment allows for complete monomer conversion within a few tens of seconds,benefiting from the superior mixing efficiency achieved in Z-shaped channels as indicated by both theoretical simulations and experimental results.Consequently,a library of well-defined BBCPs of up to 528 distinct samples can be produced within one day through automation of the continuous procedure,while keeping precise control on degree of polymerization(DP<4)and polydispersity indices(PDI<1.2).The synthetic method is generally applicable to different macromonomers with different compositions and contour lengths,yielding libraries of branched block copolymers with great diversity in physiochemical properties and chain architectures.This work presents a powerful platform for high-throughput production of branched copolymers,significantly lowering the costs of the materials for real applications.
基金the National Natural Science Foundation of China(Nos.21878088, 21476077)Key Projects of Shanghai Science and Technology Commission (No.18DZ1112703) for financial support。
文摘Erlotinib is an orally administered, highly effective, specific epidermal growth factor receptor tyrosine kinase inhibitor, used to treat non-small cell lung cancer and pancreatic cancer. The traditional synthetic methods for Erlotinib exhibit long reaction time and safety concern. Herein, we describe a novel five-step route for the synthesis of Erlotinib in flow. These five steps comprise etherification, nitration, reduction,addition and cyclization reactions. All steps were optimized and converted to continuous flow process,which drastically reduces the reaction time and considerably improves the process safety as well as the total yield. Enabled by five continuous flow units, Erlotinib is efficiently afforded with an E-factor of 38,an overall yield of 83%, and a total residence time of 25.1 min. Majority steps in this process have been optimized for quantitative conversion, which offers the possibility of telescoping the entire process.
文摘The aim of this study is to use a new configuration of porous media in a heat exchanger in continuous hydrothermal flow synthesis(CHFS)system to enhance the heat transfer and minimize the required length of the heat exchanger.For this purpose,numerous numerical simulations are performed to investigate performance of the system with porous media.First,the numerical simulation for the heat exchanger in CHFS system is validated by experimental data.Then,porous media is added to the system and six different thicknesses for the porous media are examined to obtain the optimum thickness,based on the minimum required length of the heat exchanger.Finally,by changing the flow rate and inlet temperature of the product as well as the cooling water flow rate,the minimum required length of the heat exchanger with porous media for various inlet conditions is assessed.The investigations indicate that using porous media with the proper thickness in the heat exchanger increases the cooling rate of the product by almost 40% and reduces the required length of the heat exchanger by approximately 35%.The results also illustrate that the most proper thickness of the porous media is approximately equal to 90% of the product tube's thickness.Results of this study lead to design a porous heat exchanger in CHFS system for various inlet conditions.
基金supported by the National Key Research and Development Program of China(No.2021YFA0910400 and 2019YFA0905100)the National Natural Science Foundation of China(No.32171462)+1 种基金Tianjin Synthetic Biotechnology Innovation Capacity Improvement Project(No.TSBICIP-CXRC-040)the Natural Science Foundation of Tianjin(No.21JCJQJC00110).
文摘Reductive amination by amine dehydrogenases is a green and sustainable process that produces only water as the by-product.In this study,a continuous flow process was designed utilizing a packed bed reactor filled with co-immobilized amine dehydrogenase wh84 and glucose dehydrogenase for the highly efficient biocatalytic synthesis of chiral amino alcohols.The immobilized amine dehydrogenase wh84 exhibited better thermo-,pH and solvent stability with high activity recovery.(S)-2-aminobutan-1-ol was produced in up to 99%conversion and 99%ee in the continuous flow processes,and the space-time yields were up to 124.5 g L-1 d-1.The continuous reactions were also extended to 48 h affording up to 91.8%average conversions.This study showcased the important potential to sustainable production of chiral amino alcohols in continuous flow processes.
基金the National Key Research and Development Program of China(Nos.2023YFD1700303,2022YFD17800)National Natural Science Foundation of China(Nos.21878088,21476077)for financial support。
文摘Triflumezopyrim(TFM)is a novel mesoionic pyrido[1,2-α]pyrimidinones insecticide,which acts on nicotinic acetylcholine receptors(n ACh Rs)and has no cross-resistance with other insecticides.Herein,we firstly developed a new continuous flow approach to synthesis 2-[3-(trifluoromethyl)phenyl]malonic acid,a key intermate of TFM,coupling with esterification,condensation,and hydrolysis.All three-step reactions were optimized and transformed into a continuous synthesis mode by three micro reaction units.Compared with the batch mode,the total reaction time and overall separation yield were improved from more than 12 h and 60%to 18 min and 73.38%,respectively.The solvent consumption and waste emission were significantly reduced,which also provides an eco-friendly and efficient potential tool for the development and production of mesoionic pyrido[1,2-α]pyrimidinones insecticide.
基金Project supported by the Science Project of Harbin City(No. H2001-12)the Youth Foundation of School of Municipal and Environmental Engineering in Harbin Institute of Technology(No. 01306914).
文摘The degradation of formaldehyde gas was studied using UV/TiO2/O3 process under the condition of continuous flow mode. The effects of humidity, initial formaldehyde concentration, residence time and ozone adding amount on degradation of formaldehyde gas were investigated. The experimental results indicated that the combination of ozonation with photocatalytic oxidation on the degradation of formaldehyde showed a synergetic action, e.g,, it could considerably increase decomposing of formaldehyde. The degradation efficiency of formaldehyde was between 73.6% and 79.4% while the initial concentration in the range of 1.84--24 mg/m^3 by O3/TiO2flJV process. The optimal humidity was about 50% in UV/TiO2/O3 processs and degradation of formaldehyde increases from 39.0% to 94.1% when the ozone content increased from 0 to 141 mg/m^3. Furthermore, the kinetics of formaldehyde degradation reaction could be described by Langmuir-Hinshelwood model. The rate constant k of 46.72 mg/（m^3.min） and Langmuir adsorption coefficient K of 0.0268 m^3/mg were obtained.
基金supported by the National Natural Science Foundation of China (Nos. 51808367 and 51878430)
文摘In this study,a modified continuous-flow nitrifying reactor was successfully operated for rapid cultivation of micro-granules and achieving robust nitritation.Results showed that sludge granulation with mean size of ca.100μm was achieved within three weeks by gradually increasing settling velocity-based selection pressure from 0.48 to 0.9 m/hr.Though Nitrospira like nitrite-oxidizing bacteria(NOB)were enriched in the micro-granules with a ratio between ammonia-oxidizing bacteria(AOB)and NOB of 5.7%/6.5% on day 21,fast nitritation was achieved within one-week by gradually increasing of influent ammonium concentration(from 50 to 200 mg/L).Maintaining ammonium in-excess was the key for repressing NOB in the micro-granules.Interestingly,when the influent ammonium concentration switched back to 50 mg/L still with the residual ammonium of 15–25 mg/L,the nitrite accumulation efficiency increased from 90%to 98%.Experimental results suggested that the NOB repression was intensified by both oxygen and nitrite unavailability in the inner layers of micro-granules.Unexpectedly,continuous operation with ammonium in excess resulted in overproduction of extracellular polysaccharides and overgrowth of some bacteria(e.g.,Nitrosomonas,Arenimonas,and Flavobacterium),which deteriorated the micro-granule stability and drove the micro-granules aggregation into larger ones with irregular morphology.However,efficient nitritation was stably maintained with extremely high ammonium oxidation potential(>50 mg/g VSS/hr)and nearly complete washout of NOB was obtained.This suggested that smooth and spherical granule was not a prerequisite for achieving NOB wash-out and maintaining effective nitritation in the granular reactor.Overall,the microgranules exhibited a great practical potential for high-rate nitritation.
基金Projects(40772156, 41072179) supported by the National Natural Science Foundation of China
文摘An online method using continuous flow isotope ratio mass spectrometry （CF-IRMS） interfaced with a Gasbench Ⅱ was presented to determine chlorine stable isotope composition. Silver chloride （AgCl） was quantitatively derived from chloride by using silver nitrate （AgNO3）, and then was reacted with iodomethane （CH3Ⅰ） to produce methyl chloride （CH3Cl）. A GasBench Ⅱ equipped with a PoraPlot Q column was used to separate CH3Cl from any other gas species. Finally, chlorine stable isotope analysis was carried out on CH3Cl introduced to the IRMS in a helium stream via an active open split. The minimum amount of Cl used in this method is of the order of 1.4 μmol. Inter-laboratory and inter-technique comparisons show that the total uncertainty incorporating both the precision and accuracy of this method is better than 0.007%. Furthermore, ten seawaters sampled from different locations have a narrow δ37Cl value range from -0.008% to 0.010%, with a mean value of （0.000±0.006）%. This supports the assumption that any seawater can be representative of standard mean ocean chloride （SMOC） and used as an international reference material.
基金supported by the National Natural Science Foundation of China (No. 51208231)
文摘A novel method based on the selective pressure of particle size （particle-size cultivation method, PSCM） was developed for the cultivation and operation of aerobic granular sludge in a continuous-flow reactor, and compared with the conventional method based on the selective pressure of settling velocity （settling-velocity cultivation method, SVCM）. Results indicated that aerobic granules could be cultivated in continuous operation mode by this developed method within 14 days. Although in the granulation process, under particle-size selective pressure, mixed liquor suspended solids （MLSS） in the reactor fluctuated greatly and filamentous bacteria dominated the sludge system during the initial operation days, no obvious difference in profile was found between the aerobic granules cultivated by PSCM and SVCM. Moreover, aerobic granules cultivated by PSCM presented larger diameter, lower water content and higher specific rates of nitrification, denitrifieation and phosphorus removal, but lower settling velocity. Under long term operation of more than 30 days, aerobic granules in the continuous-flow reactor could remain stable and obtain good chemical oxygen demand （COD）, NH4^＋-N, total nitrogen （TN） and total phosphorus （TP） removal. The results indicate that PSCM was dependent on the cultivation and maintenance of the stability of aerobic granules in continuous-flow bioreactors.
基金financially supported by the National Natural Science Foundation of China(No.52170049).
文摘A continuous flow bioreactor was operated for 300 days to investigate partial nitritation(PN)of mature landfill leachate,establishing the long-term performance of the system in terms of the microbial community composition,evolution,and interactions.The stable operation phase(31-300 d)began after a 30 days of start-up period,reaching an average nitrite accumulation ratio(NAR)of 94.43%and a ratio of nitrite nitrogen to ammonia nitrogen(NO_(2)^(−)-N/NH_(4)^(+)-N)of 1.16.Some fulvic-like and humic-like compounds and proteins were effectively degraded in anaerobic and anoxic tanks,which was consistent with the corresponding abundance of methanogens and syntrophic bacteria in the anaerobic tank,and organic matter degrading bacteria in the anoxic tank.The ammonia-oxidizing bacteria(AOB)Nitrosomonas was found to be the key functional bacteria,exhibiting an increase in abundance from 0.27%to 6.38%,due to its collaborative interactions with organic matter degrading bacteria.In-situ inhibition of nitrite-oxidizing bacteria(NOB)was achieved using a combination of free ammonia(FA)and free nitrous acid(FNA),low dissolved oxygen(DO)with fewer bioavailable organics conditions were employed to maintain stable PN and a specific ratio of NO_(2)^(−)-N/NH_(4)^(+)-N,without an adverse impact on AOB.The synergistic relationships between AOB and both denitrifying bacteria and organic matter degrading bacteria,were found to contribute to the enhanced PN performance and microbial community structure stability.These findings provide a theoretical guidance for the effective application of PN-Anammox for mature landfill leachate treatment.
基金This study was supported by the National Natural Science Foundation of China(Nos.21620102008,and 21777040)the Beijing Natural Science Foundation(No.8182051)the Fundamental Research Funds for the Central Universities(No.2017ZZD07).
文摘The creation of an environmentally friendly synthesis method for silver nanomaterials(Ag-NPs)is an urgent concern for sustainable nanotechnology development.In the present study,a novel straightforward and green method for the preparation of silver nanoparti-cle/reduced graphene oxide(AgNP/rGO)composites was successfully developed through the combination of phytosynthesis,continuous flow synthesis and microwave-assistance.Oriental persimmon(Diospyros kaki Thunb.)extracts were used as both plant reducing and capping agents for fast online synthesis of AgNP/rGO composites.The experimental param-eters were optimized and the morphologies of the prepared materials were investigated.The characterization results reveal that spherical AgNPs were quickly synthesized and uni-formly dispersed on rGO sheets using the proposed online system.Fourier transform in-frared spectroscopy analysis confirmed that phenols,flavonoids,and other substances in the plant extracts played a decisive role in the synthesis of AgNP/rGO composites.Using sodium borohydride(NaBH4)degradation of p-nitrophenol(4-NP)as a model,the catalytic activity of the prepared AgNP/rGO materials was evaluated.The complete degradation of 4-NP was achieved within 12 min through the use of AgNP/rGO materials,and the compos-ite had a much better catalytic activity than the bare AgNPs and rGO had.Compared with the conventional chemical method,our online method is facile,fast,cost-efficient,and en-vironmentally friendly.
基金National Natural Science Foundations of China(No.61273035,No.71071115)National High-Tech R&D Program for CIMS,China(No.2009AA043000)
文摘To quickly and accurately estimate the expected work-in-process (WIP)of material intersection points in continuous automated material handling systems (AMHSs) ,a queuing-based performance analytical model was presented for continuous flow transporters (CFTs) . In the modeling procedure which considered layout of crossovers and the variability of service time of turntables, an M /G /1 queuing model with multi-class customers and a non-preemptive priority M /G /1 queuing model with multi-class customers were introduced to accurately present the queuing WIP of each material intersection point and perform the analytical model. Finally,300 mm wafer fabrication facilities (fabs)with 24 bays were applied to evaluating the proposed model. Compared with results of an Arena simulation, the model performs well in evaluating the number of queuing WIP of the intersection points and overall system of CFTs in AMHSs.
基金the National Natural Science Foundation of China(NSFC,No.51573216)the NSF of Guangdong Province for financial support。
文摘Porous materials play an important role in chemical catalysis,separation and other industrial applications.High-efficiency preparation of porous materials has become an active research area.Conventional synthesis of porous materials has been dominated by one-pot solution processing conditions carried out by bulk mixing under conventional electric heating via hydrothermal,solvothermal or ionothermal reactions where high temperatures and pressures are the standard.Continuous flow synthesis has many key advantages in terms of efficient mass and heat transfer,precise control of residence times,improved opportunities for automation and feedback control of synthesis,scaling-up reactions and improved safety parameters compared to above mentioned conventional batch scale synthetic methods.In this review,continuous flow synthesis of various crystalline porous materials such as metal-organic frameworks(MOFs),covalent-organic frameworks(COFs),porous organic cages and zeolites is discussed.Combination of microfluidic methods with other techniques are also shown including various heating ways and various methods of substrate adding.
基金The research was supported by the National Basic Research Program(“973”Program)of China under contract No.2002CB412405the Key Science and Technology Plan of the Ministry of Education of China under contract No.[2000]156-00079the Joint Sino-German Project under contract No.03F0189A.
文摘Several methods for analysis of dissolved total phosphorus in seawater were reviewed. Discussions were focused on UVirradiation and persulphate oxidation methods which are the most popular dissolved organic phosphorus determinationmethods presently. The compounds used for the phosphorus recovery test were categorized into three groups accordingto their chemical structure. It was found that low power UV irradiation can decompose POC or PC bonds efficientlybut may be inefficient for POP bonds. Heating-bath in acid condition is useful for decomposing POP bonds. Usingthe continuous flow analysis system (Auto-analyzer II), UV digestion and heating-bath, series experiments were carriedout based on the above analysis. Eleven model compounds were employed for the phosphorus recovery test and thefactors influencing the decomposition efficiency of dissolved compounds containing phosphorus were clarified. Finally,the optimal design for determination of dissolved total phosphorus in seawater based on the routine continuous flowanalysis system was presented. For the organic mono-phosphate, the recovery is more than 90% and a recovery of33%~51% was obtained for inorganic or organic polyphosphates. Up to now, this is the highest decompositionefficiency for dissolved phosphorus based on the continuous flow analysis system.
基金supported by the National Natural Science Foundation of China (10872096)the Open Fund of State Key Laboratory of Explosion Science and Technology, Beijing University of Science and Technology (KFJJ09-13)
文摘Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems.
基金Item Sponsored by National Outstanding Young Scientist Foundation of China(50925415)Fundamental Research Funds for Central Universities of China(N100102001)
文摘The metallurgical phenomena occurring in the continuous casting mold have a significant influence on the performance and the quality of steel product.The multiphase flow phenomena of molten steel,steel/slag interface and gas bubbles in the slab continuous casting mold were described by numerical simulation,and the effect of electromagnetic brake（EMBR） and argon gas blowing on the process were investigated.The relationship between wavy fluctuation height near meniscus and the level fluctuation index F,which reflects the situation of mold flux entrapment,was clarified.Moreover,based on a microsegregation model of solute elements in mushy zone with δ/γ transformation and a thermo-mechanical coupling finite element model of shell solidification,the thermal and mechanical behaviors of solidifying shell including the dynamic distribution laws of air gap and mold flux,temperature and stress of shell in slab continuous casting mold were described.
文摘The direct hydroxylation of benzene to phenol catalyzed by activated carbon-supported Fe （Fe/AC） in acetonitrile using H2O2 as the oxidant was studied in a continuous flow reactor. Results showed that the continuous operation could obtain high phenol yield of 28.1%, coupled with the turnover frequency of 3 h^-1, and high selectivity of 98% under mild condition. The catalyst was characterized by N2 adsorption/desorption, Boehm titration, X-ray photoelectron spectra, and Fourier transform infrared spectroscopy. It was observed that iron may interact with the carboxyl group forming iron-carboxylate like species, which act as the active phase. The apparent activation energy obtained by fitting an Arrhenius model to the experimental data was 13.4 kJ/mol. The reaction order was calculated to be about i, 0.2 for benzene and 0.7 for H202.
文摘Continuous flow intersections (CFIs), also known as displaced left turns (DLTs), are a type of alternative intersection designed to improve operations at locations with heavy left-turn movements by reallocating these vehicles to the left side of opposing traffic. Currently, simulation is commonly used to evaluate operational performance of CFIs. However, this approach requires significant on-site data collection and is highly dependent on the analyst’s ability to correctly model the intersection and driver behavior. Recently, connected vehicle (CV) trajectory data has become widely available and presents opportunities for the direct measurement of traffic signal performance measures. This study utilizes CV trajectory data to analyze the performance of a CFI located in West Valley City, UT. Over 4500 trajectories and 105,000 GPS points are analyzed from August 2021 weekday data. Trajectories are linear-referenced to generate Purdue Probe Diagrams (PPDs) and extended PPDs to estimate split failures (SF), arrivals on green (AOG), traditional Highway Capacity Manual (HCM) level of service (LOS), and the distribution of stops. The estimated operational performance showed effective progression during the PM peak period at all the critical internal storage areas with AOG levels at exit traffic signals between 83% and 100%. In contrast, all external approaches with longer queue storage areas had AOG values ranging from 2% to 81% during the same time period. The presented analytical techniques and summary graphics provide practitioners with tools to evaluate the performance of any CFI where CV trajectories are available without the need for on-site data collection.
基金funded by the National Natural Science Foundation of China(52222704 and 52177107).
文摘In an integrated electricity-gas system(IEGS),load fluctuations affect not only the voltage in the power system but also the gas pressure in the natural gas system.The static voltage stability region(SVSR)method is a tool for analyzing the overall static voltage stability in a power system.However,in an IEGS,the SVSR boundary may be overly optimistic because the gas pressure may collapse before the voltage collapses.Thus,the SVSR method cannot be directly applied to an IEGS.In this paper,the concept of the SVSR is extended to the IEGS-static stability region(SSR)while considering voltage and gas pressure.First,criteria for static gas pressure stability in a natural gas system are proposed,based on the static voltage stability criteria in a power system.Then,the IEGS-SSR is defined as a set of active power injections that satisfies multi-energy flow(MEF)equations and static voltage and gas pressure stability constraints in the active power injection space of natural gas-fired generator units(NGUs).To determine the IEGSSSR,a continuation MEF(CMEF)method is employed to trace the boundary point in one specific NGU scheduling direction.A multidimensional hyperplane sampling method is also proposed to sample the NGU scheduling directions evenly.The obtained boundary points are further used to form the IEGSSSR in three-dimensional(3D)space via a Delaunay triangulation hypersurface fitting method.Finally,the numerical results of typical case studies are presented to demonstrate that the proposed method can effectively form the IEGS-SSR,providing a tool for IEGS online monitoring and dispatching.
