Continuous Flow Method Research Articles

Mild Microfluidic Approaches to Oxide Nanoparticles Synthesis

Oxide nanoparticles (oxide NPs) are advanced materials with a wide variety of applications in different fields. The use of continuous flow methods is particularly appealing for their synthesis due to the high control achieved over the reaction conditions and the easy process scalability. The present review focuses on the preparation of oxide NPs using microfluidic setups at low temperature (≤80 °C), since the employment of mild reaction conditions is crucial for developing sustainable and cost‐effective processes. A particular emphasis will be put on the improvement over the final product features (e. g., size, shape, and size distribution) given by flow methods with respect to conventional batch procedures. The main issues that arise by treating NPs suspensions in microfluidic systems are product deposition or channel clogging; mitigation strategies to overcome these drawbacks will also be presented and discussed.

SHIP BALLAST WATER EXCHANGE METHODS ON BOARD SHIPS

The IMO established rules for ballast water exchange procedures to be carried out in oceanic regions. There are three known methods: - Sequential method; - Overflow or continuous flow method; - Brazilian dilution method. All three are not 100% efficient. It is known that they present structural problems to the ship, and even so they do not guarantee total effectiveness in the elimination of exotic species. In addition to these methods, other types of methods are already being tested at American Universities. The present work presents in-depth studies on ballast water exchange procedures.

Microwave-assisted preparation of polyphosphoric acid in a continuous-flow reactor

Abstract Polyphosphoric acid (PPA) is widely used in inorganic salt production, petrochemical industry, electronic material preparation and other manufacturing industries. Conventional preparation methods of PPA has disadvantages of pollution, high energy consumption and long production time. To address this problem, microwave continuous-flow preparation may be a desirable way due to its advantages of environmentally-friendly, rapidity and high efficiency. Therefore, to explore the process of preparing PPA by microwave continuous-flow method, a continuous-flow microwave reactor was designed for the dehydration process of orthophosphoric acid to prepare PPA in this paper. The microwave-assisted dehydration process was studied in comparison with the conventional dehydration process and the “closed” microwave-assisted dehydration process in terms of energy efficiency, process times and treatment capacity. The effect of input microwave power, reduced pressure and inlet flow velocity of orthophosphoric acid on the performance of the dehydration process was studied. The results showed that the influence of the microwave power on the temperature rise process during dehydration is greater than that of the reduced pressure. Moreover, the inlet flow rate has a great impact on the treatment capacity and product quality of the dehydration process. Bedsides, the comparison with the other two methods showed that microwave heating can effectively shorten the dehydration time, and the continuous-flow treatment can effectively improve the treatment capacity of microwave heating. The perspectives of the process scale-up by continuous-flow microwave heating method is also discussed.

Online Monitoring of Voltage Stability Margin in Kosovo Power System Using Local Measurements

This paper presents an analysis of the voltage stability of the Kosovo power system. The first part of the study has included a detailed analysis of the Kosovo power system by using the continuous power flow method, with an emphasis on the determination of the P–V curve of voltage stability. Thus, it has identified the weak and critical points of the power system in terms of voltage stability and has defined the margin of instability. In order to achieve online monitoring of voltage stability in the power system, it is proposed to place phasor measurement units in the weakest critical buses. Furthermore, the Thevenin equivalent method has been applied to evaluate voltage stability in the critical buses. The maximum transmissible real power to the weak buses in the system can be achieved when load impedance is equal to the Thevenin impedance. The load and Thevenin impedance values have been obtained from the relevant PMU data. Following online monitoring of voltage stability in the power system, the developed voltage stability load bus index can be used as useful information by system operators in order to undertake appropriate countermeasures to prevent voltage collapse.

Examining samarium sorption in biochars and carbon-rich materials for water remediation: batch vs. continuous-flow methods

Samarium (Sm) sorption from aqueous solutions was evaluated in biochars (derived from castor meal (CM), eucalyptus forest residues (CE), sugarcane bagasse (SB) and green pericarp of coconut (PC)) and in other carbon-rich materials (coal fines (CF); two commercial activated charcoals (GAC, NGAC)) by applying batch and continuous-flow sorption experiments. Batch experiments revealed great Kd values, in the range of 104–105 L kg−1, and high Sm sorption percentages (>97%, except for SB) in the range of environmental representative concentrations, using as-received materials, with no further treatments. Maximum sorption capacities were derived from sorption isotherms using the Langmuir model (from 1.2 to 37 mg g−1). Continuous-flow sorption experiments permitted to obtain maximum sorption capacities by mass balance and by fitting the experimental breakthrough curves to Thomas and Yan models. CF exhibited the greatest maximum sorption capacity (40 mg g−1) besting the commercial activated charcoals, while CM was established as the best biochar (7.2 mg g−1), with similar results to NGAC (12 mg g−1) but worse than GAC (36 mg g−1). The contribution of cation exchange in Sm sorption was confirmed to be significant for most materials based on the analyses of cations leached during continuous-flow sorption experiments. Maximum sorption capacities derived from Langmuir fitting correlated well with maximum sorption capacities obtained from continuous-flow experiments. Both methods were confirmed to be suitable to determine the maximum Sm sorption capacity of the materials and then to propose the most suitable materials that can act as alternative to commercial activated charcoals.

Recent Progress in Drug Release Testing Methods of Biopolymeric Particulate System.

Biopolymeric microparticles have been widely used for long-term release formulations of short half-life chemicals or synthetic peptides. Characterization of the drug release from microparticles is important to ensure product quality and desired pharmacological effect. However, there is no official method for long-term release parenteral dosage forms. Much work has been done to develop methods for in vitro drug release testing, generally grouped into three major categories: sample and separate, dialysis membrane, and continuous flow (flow-through cell) methods. In vitro drug release testing also plays an important role in providing insight into the in vivo performance of a product. In vitro release test with in vivo relevance can reduce the cost of conducting in vivo studies and accelerate drug product development. Therefore, investigation of the in vitro–in vivo correlation (IVIVC) is increasingly becoming an essential part of particulate formulation development. This review summarizes the principles of the in vitro release testing methods of biopolymeric particulate system with the recent research articles and discusses their characteristics including IVIVC, accelerated release testing methods, and stability of encapsulated drugs.

Creating ultrahigh surface area functional carbon from biomass for high performance supercapacitor and facile removal of emerging pollutants

Recent decade has seen enormous interest in developing cost effective, simple and greener method of utilizing naturally abundant and renewable resources to mitigate the concerns relating contaminated water sources and store green energy. Carbon materials derived from biomass have drawn great attention because of their abundance, easy processability, tunable surface properties and relatively low cost. Present work demonstrates the conversion of abundant and toxic weed, Parthenium hysterophorous to porosity enriched ultrahigh surface area activated carbon with a surface area of 4014 m2/g and a large porous volume of 2.0419 cm3/g. The optimized carbon materials before and after activation showed crumpled sheet-like morphology with oxygenated functionalities (C/O = 6.352) as confirmed by different analytical tools. Electrochemical studies revealed that the supercapacitor device assembled using the as prepared carbon material manifest an significant specific capacitance of 270 F/g, exhibiting excellent capacity retention of 98.5 % even after 30,000 cycles at an increased current density of 10 A/g. Further, a membrane was prepared using functional carbon material for the removal of different organic pollutants such as dyes (methylene blue, malachite green, eriochrome black T, congo red) and pharmaceutical wastes (paracetamol, ciprofloxacin) from aqueous media. The functional carbon based membrane showed high rejection for cationic dyes (93–99.5%) comparing to anionic dyes (46–67%) with a flux rate in the range of 820–840 Lm-2h−1 and maximum adsorption capacity of 194 mg/g for methylene blue dye. Similarly, for cationic pharmaceutical wastes higher rejection (90–95%) was achieved with an average flux of 830 Lm-2h−1. Moreover, recyclability studies of the membrane affirmed a retention of 91.6% rejection of methylene blue even after 10 consecutive cycles without compromising the flux rate which confirmed the suitability of the toxic weed derived functional carbon as a sustainable alternative for water purification in a continuous flow method.

Next Generation Immunotherapies – Emerging Strategies for Immune Modulation against Cancer, Infections, and Beyond

Next Generation Immunotherapies – Emerging Strategies for Immune Modulation against Cancer, Infections, and Beyond

A simple method to generate [18F]triflyl fluoride for 18F radiosynthesis

A simple, continuous-flow solid-phase radiosynthesis method has been developed for the generation of [18F]triflyl fluoride as a source of [18F]fluoride for the preparation of 18F labeled radiopharmaceuticals without the need for an azeotropic drying step. After [18F]fluoride was trapped and dried on an anion-exchange resin cartridge, gaseous [18F]triflyl fluoride was generated directly by eluting the cartridge with a solution of PhN(OTf)2, followed by isolation from the eluted reaction mixture via an empty cartridge and conversion to [18F]fluoride in a basic solution for radiofluorination. A peristaltic pump was used to maintain flow through the above stages, eventually providing reaction-ready [18F]fluoride in over 90% radiochemical yield in less than 10 min. Up to 0.057 µg non-radioactive fluoride was introduced from the reagents and components used during the above processes. Several radiolabeling reactions were carried out using the [18F]fluoride generated in this manner, affording the labeled products in good to high radiochemical yields. This method should have great potential for the safe and convenient preparation of 18F labeled radiopharmaceuticals.

Formation and utility of reactive ketene intermediates under continuous flow conditions

Continuous flow systems offer unique benefits in the generation and manipulation of sensitive reactive intermediates such as ketenes. To this end, the last decade has witnessed the development of continuous flow methods for the generation of ketenes by means of chemical, thermal, and photochemical activation modes. This perspective covers these advances and the downstream reactivity of ketenes in continuous flow technology.

Investigating the Effect of Dwell Time on the Physical Properties of Nano-sized Tin dioxide (SnO2) Prepared Through a Continuous Microwave Flow Process

Tin dioxide (SnO2) is a well-known catalytic material used to catalyze different organic dyes and gas sensors. Similarly, it is also considered a good sensing and optoelectronic material. In this work, SnO2 has been synthesized using a microwave-assisted continuous flow method. The effect of dwell time was utilized to study its effects on the physical properties of SnO2. X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Transmission Electron Microscopy (TEM) and Bruner Emmit-Teller (BET) techniques were used to characterize the synthesized SnO2. UV-Visible spectroscopy technique was employed to calculate the energy bandgap, which exhibited a decrease in the energy bandgap from 3.44 to 3.33 eV on increasing the dwell time. XRD results exhibited an increase in the degree of crystallinity from 56 to 63% and a reduction in the particle size from 3.74 to 2.75 nm. Where, BET study revealed a shrinkage in the surface area from 159 to 154 m2g- 1. Photoluminescence (PL) study was conducted to investigate the surface defects. Photocatalytic efficiency of the SnO2 was probed against the photodegradation of methylene blue dye and this study revealed that SnO2 is a good photocatalytic material.

Nanoengineering Apolipoprotein A1‐Based Immunotherapeutics

AbstractIn the slipstream of targeting the adaptive immune system, innate immunotherapy strategies are being developed. In this context, technologies based on natural carrier vehicles that inherently interact with the innate immune system, are increasingly being considered. Immunoregulatory nanotherapeutics based on natural apolipoprotein A1 (apoA1) are discussed here. This protein is a helical, amphipathic macromolecule and the main constituent of high‐density lipoprotein. In that capacity, apoA1 interacts specifically with innate immune cells, such as monocytes and macrophages, to collect and transport lipophilic molecules throughout the body. Exactly these unique features make apoA1 a compelling elementary constituent of biocompatible self‐assembled nanotherapeutics. Such apoA1‐based nanotherapeutics (A1‐nanotherapeutics) can be engineered and functionalized to induce or mitigate an innate immune response or to orchestrate an adaptive immune response through antigen delivery to dendritic cells. The authors first discuss apoA1's properties and how these can be exploited to generate libraries of A1‐nanotherapeutics using advanced manufacturing approaches such as microfluidics or continuous flow methods. Using high‐throughput in vitro screening methods and in vivo imaging to identify promising formulations are then recommend. Finally, three distinct immunotherapy strategies are proposed to effectively treat a variety of diseases—including cancer, infection, and cardiovascular disease—and promote allograft survival in transplantation.

Electrochemical Oxidation Dearomatization of Anisol Derivatives toward Spiropyrrolidines and Spirolactones

Spiro compounds are widely prevalent in biological activities and natural products. However, developing new strategies for their efficient synthesis and derivatization remains a challenge. Outstand...

Measuring Isobaric Heat Capacity of Fluids in the Critical Region by Continuous-Flow Adiabatic Calorimetry Method

Measuring Isobaric Heat Capacity of Fluids in the Critical Region by Continuous-Flow Adiabatic Calorimetry Method

C-N Bond Formation by Consecutive Continuous-Flow Reductions towards A Medicinally Relevant Piperazine Derivative.

A new, continuous-flow consecutive reduction method was developed for the C-N bond formation in the synthesis of the key intermediate of the antipsychotic drug cariprazine. The two-step procedure consists of a DIBAL-H mediated selective ester reduction conducted in a novel, miniature alternating diameter reactor, followed by reductive amination using catalytic hydrogenation on 5% Pt/C. The connection of the optimized modules was accomplished using an at-line extraction to prevent precipitation of the aluminum salt byproducts.

Comparison of Three Measurement Principles on Water Triple Oxygen Isotopologues

The widespread method for measuring Δ17O (17O-excess) is an offline CoF3 (Cobalt tri-fluoride) conversion of water to molecular oxygen with subsequent isotope determination by dual inlet mass spectrometry. High precisions for Δ17O measurements, using CoF3 water conversion, are so far only possible with off-line methods. Here we report on an improved and modified online continuous flow method intended for high precision triple oxygen isotope analysis. This method is improved by optimizing the reactor (site for conversion of H2O into oxygen through the chemical reaction) compositions, size of the fused silica capillary, flow regulator, and data treatment. Our modified online continuous method was further compared with the recently developed cavity ring down measurement principle. The precision is significantly better for the commercially available laser-based system than our current version of improved online CoF3 conversion method using mass spectrometry. Factors identified for limiting precision in our continuous flow system are: (i) compaction of the reactor with time that leads to the restriction of flow rate of carrier gas, (ii) the CoF3 treatment, (iii) the amount of CoF3 inside the reactor, (iv) the pore size of the steel frit, and (v) the metallic tube. Changes in all of these items as well as the dimension of the fused silica capillary, the positioning of the fused silica capillary in the open split, and the memory effect can also lead to a declining precision. These limiting factors for precision still provide us enough space for further improvement of our improved online method which will be worthwhile for the measurement of smaller aliquot samples as fluid inclusions for palaeoclimatic applications. With present improvement, multiple injections (n = 15 or even more) should be applied to obtain a precision better than 10 per meg for Δ17O. Furthermore, a comparison of the laser-based system with an improved conventional equilibration method has been made on precipitation samples originating from Jungfraujoch.

Ring Opening/Site Selective Cleavage in N-Acyl Glutarimide to Synthesize Primary Amides

A LiOH-promoted hydrolysis selective C-N cleavage of twisted N-acyl glutarimide for the synthesis of primary amides under mild conditions has been developed. The reaction is triggered by a ring opening of glutarimide followed by C-N cleavage to afford primary amides using 2 equiv of LiOH as the base at room temperature. The efficacy of the reactions was considered and administrated for various aryl and alkyl substituents in good yield with high selectivity. Moreover, gram-scale synthesis of primary amides using a continuous flow method was achieved. It is noted that our new methodology can apply under both batch and flow conditions for synthetic and industrial applications.

Continuous-flow synthesis of MIL-53(Cr) with a polar linker: probing the nanoscale piezoelectric effect

MIL-53(Cr) MOF material was designed and prepared with polar linker including fluorine group. The MIL-53(Cr)-F nanoparticles can be fabricated by continuous flow method at large scale, and these materials display nanoscale piezo-responses.

An identity authentication method for ubiquitous electric power internet of things based on dynamic gesture recognition

This paper presents a novel algorithm for gesture recognition and identity authentication based on continuous hidden Markov model (CHMM) and optical flow method. This study aims to solve the information security problems about ubiquitous electric power internet of things. In this system, the optical flow method is used to segment and extract the features of the preprocessed dynamic gesture information to obtain the features of the dynamic gesture motion track, and the CHMM is chosen to establish a valid user dynamic gesture model, which leads to ensuring the dynamic gestures are accurately recognised. The proposed method is test on accurately recognise the dynamic gestures and the result is compared with the dynamic time warpring (DTW) algorithm and practical swarm optimisation-radial basis function network (PSO-RBFN) algorithm. The result of the comparisons illuminates the superiority of the proposed method in terms of accuracy of identity authentication.

Continuous flow as an enabling technology: a fast and versatile entry to functionalized glyoxal derivatives

We herein report two complementary strategies employing organolithium chemistry for the synthesis of glyoxal derivatives. Micro-mixer technology allows for the generation of unstable organometallic intermediates and their instantaneous in-line quenching with esters as electrophiles. Selective mono-addition was observed via putative stabilized tetrahedral intermediates. Advantages offered by flow chemistry technologies facilitate direct and efficient access to masked 1,2-dicarbonyl compounds while mitigating undesired by-product formation. These two approaches enable the production of advanced and valuable synthetic building blocks for heterocyclic chemistry with throughputs of grams per minute.