Continuous Injection Mode Research Articles

Comparison of Different High-Speed Countercurrent Chromatography Injection Modes for the Separation of Glabridin.

In this work, different injection modes (single injection, overlapping injection, and continuous injection) of countercurrent chromatography were used and compared for the isolation and purification of glabridin from the crude extract of Glycyrrhiza glabra. The two-phase solvent system consisting of n-hexane/ethyl acetate/methanol/water (5:4:5:4, v/v) was employed as stationary and mobile phases. Compared with single injection mode, both overlapping injection and continuous injection modes exhibited higher separation efficiency at the same sample loading capacity. Their total separation times were 89.68% and 53.97% of the single injection mode, and the total solvent consumption were 74.88% and 52.49% of the single injection mode, respectively. Meanwhile, the yield, purity, and recovery rate of these three injection modes were almost the same. It was demonstrated that high-speed countercurrent chromatography in continuous injection mode was the most effective way for separating glabridin in three methods and it can be further applied to the separation of other economically valuable natural products.

Separation of astragaloside IV from Astragalus membranaceus based on high-speed countercurrent chromatography in continuous injection mode.

Astragaloside IV (AS-IV) is an index for the quality evaluation of the traditional Chinese medicine Astragalus and an important material basis for Astragalus to exert its medicinal effects, and it is difficult to obtain a single AS-IV by ordinary separation methods. To find a new isolation method that can prepare AS-IV quickly and efficiently. AS-IV was isolated from Astragalus membranaceus extract by high-speed countercurrent chromatography using a two-phase solvent system consisting of ethyl acetate/n-butanol/water (4.2:0.8:5, v/v) at a speed of 950 rpm at a flow rate of 2mL/min using one of the high-speed countercurrent chromatographic sequential injection models developed during the previous study. Compared with the common countercurrent chromatographic separation, this separation method increased the injection volume and yield by 4-fold and 4.47-fold, respectively, with only about 1.2-fold increase in solvent consumption and separation time, and the purity was basically not reduced, and 55.9mg of AS-IV, with a purity of 96.95%, was finally prepared from 400 mg of the crude extract in 240 min. The continuous injection mode of high-speed countercurrent chromatography was able to successfully prepare a large amount of AS-IV with high purity at one time.

An integrated strategy for combining three-phase liquid-liquid extraction with continuous high-speed countercurrent chromatography: Highly efficient in isolating and purifying zeaxanthin from the industrial crop Lycium barbarum L.

Zeaxanthin, a carotenoid, has been widely concerned for its high medicinal and nutritional value. In this work, the crude zeaxanthin was firstly extracted from saponified Lycium barbarum L. fruits by three-phase mixture solvent system consisting of n-hexane-methyl acetate-acetonitrile-water (4:4:3:4, v/v). This extraction process can effectively enrich the trace zeaxanthin in Lycium barbarum. Furthermore, the crude zeaxanthin was purified by high-speed countercurrent chromatography (HSCCC) based on continuous injection mode. The key purification parameters including flow rate, revolution and sample concentration, were systematically and carefully studied. Using a two-phase solvent mixture consisting of n-hexane-ethyl acetate-ethanol-water (8:2:7:3, v/v) in the elution-extrusion mode, a sample of zeaxanthin with a purity of 82.94% was obtained from 500 mg of crude extract under optimum conditions. This is the first report on the efficient separation and purification of zeaxanthin from Lycium barbarum L. fruit by three-phase solvent extraction combined with continuous HSCCC.

An efficient high-speed counter-current chromatography method for the preparative separation of sesquiterpenoids from the rhizomes of Cyperus rotundus L. combined with evaluation of the anti-inflammation activity in vitro and molecular docking.

Cyperus rotundus L. has been extensively used in ancient medication for the treatment of different disorders worldwide, in which sesquiterpenes are the most representative components. In this study, sesquiterpenes were effectively purified by two-dimensional counter-current chromatography in combination with continuous injection and inner-recycling mode with a solvent system of n-hexane/ethyl acetate/methanol/water (1:0.2:1:0.2, v/v/v/v). For one-dimension separation, continuous injection mode was used with three times injection and the inner-recycling mode was adopted for the separation of two mixtures for two-dimensional separation. Finally, four sesquiterpenoids, including scariodione (1), cyperenoic acid (2), scariodione (3), and α-cyperone (4), were obtained with purities over 98%. Mass spectrometry and nuclear magnetic resonance were applied to identify their structures. The results from the anti-inflammation effect with zebrafish demonstrated that cyperenoic acid exhibited stronger anti-inflammation activity. Molecular docking results suggested that cyperenoic acid possessed lower binding energies -9.4545kcal/mol with 1CX2 to form formed hydrogen bond interaction with ARG120. In general, all the obtained findings proved that the strong anti-inflammation capacity of cyperenoic acid can have the potential of being adopted for treating diseases resulting from inflammation.

The microbial and functional reconstruction of instable syntrophic propionate-oxidizing methanogenesis by system recovering and injection modes changing

Microbial enrichment is an effective method to obtain highly abundant syntrophic methanogenic propionate-degrading microbial consortia (syntrophic consortia) in complex environments. Nevertheless, there were few researches studying dynamic microbial community change and syntrophic mechanisms over a long-time bioreactor operation. In this study, the highly efficient syntrophic consortia were enriched in the anaerobic bioreactor, and the effect of propionic acid loading (PAL) on microbial community structure and functional pathways was investigated. By single injection mode (30 mL propionic acid was injected into the reactor once per day), acid accumulation occurred severely at the PAL of 2.7 g/(L·d). After the injection mode was changed to continuous injection mode (a syringe pump was used to inject 30 mL propionic acid evenly in 8 h), the reactor performance was more stable and the volumetric biogas production (VBP) reached 0.96 L/(L·d). 16S rDNA sequencing analysis and gene predictions showed that microbial community structures, functional microorganisms and metabolic pathways varied at different PALs and different injection modes. When the propionic acid shock was great, hydrogenic methanogenesis was the major pathway to relieve the acid accumulation. In continuous injection mode, the bacterial structure was more stable. Syntrophobacter became the dominant propionate oxidation bacterium and acetoclastic methanogenesis conducted by Methanosaeta enhanced. This study provides an effective method for the microbial enrichment in the rate-limiting step of anaerobic digestion and lays a foundation for the development of bio-enhancement with high organic loading.

Impact of Particle Size Polydispersity on Chemical Looping Combustion of Biomass under a Continuous Injection Mode

Particle size polydispersity considerably influences the chemical looping combustion (CLC) of solid fuels. In the present work, a three-dimensional multiphase particle-in-cell (MP-PIC) method was established and applied to study the full-loop CLC of biomass under a continuous injection mode. After model validation, the gas–solid flow characteristics, solid circulation rate (SCR), particle mixing in a fuel reactor (FR), and biomass leakage at different oxygen carrier (OC) particle size distribution (PSD) widths and biomass densities were systematically explored. The results showed that OC particles significantly stratified within the FR and both loop seals. Moreover, the fluctuation amplitude of the SCR decreased as the OC PSD width increased. Small biomass particles were more likely to leak. The number fraction of total leaked biomass particles first decreased and then increased as the OC PSD width increased. In the FR, small OC particles were primarily distributed in the upper part of the bed, and large particles were mainly distributed in the lower part. In addition, within the test range, the magnitude of the density difference between biomass and OC particles positively correlated with the likelihood of biomass leaking. These observations are all beneficial for the design and optimization of the CLC process of biomass.

An efficient high-speed counter-current chromatography method for the preparative separation of potential antioxidants from Paeonia lactiflora Pall. combination of in vitro evaluation and molecular docking.

Paeonia lactiflora Pall., one of the most famous classical herbal medicine, has been used to treat diseases for over 1200 years. In this research, the functional ingredients were purified by online-switch two-dimensional high-speed counter-current chromatography combined with inner-recycling and continuous injection mode. The antioxidant activity was evaluated by investigating the 2,2'-azobis (2-amidinopropane) dihydrochloride-induced oxidant damage in vitro and confirmed through molecular docking. n-Butanol/ethyl acetate/water (2:3:5, v/v) solvent system was used for the first-dimensional separation and optimized the sample loading. Two pure compounds and a polyphenol-enriched fraction were separated. The polyphenol-enriched fraction was separated with a solvent system n-hexane/ethyl acetate/methanol/water (2:8:4:6, v/v) with continuous injection mode. Five compounds were successfully separated, including gallic acid (1), methyl gallate (2), albiflorin (3), paeoniflorin (4), and ethyl gallate (5). Their structures were identified by mass spectrometry and NMR spectroscopy. The results from the antioxidant effect showed that albiflorin had stronger antioxidant activity. Molecular docking results indicated that the affinity energy of the identified compounds ranged from -3.79 to -8.22kcal/mol and albiflorin showed the lowest affinity energy. Overall, all those findings suggested that the strong antioxidant capacity of albiflorin can be potentially used for the treatment of diseases caused by oxidation.

Experimental analysis of oil displacement by hybrid engineered water / chemical EOR approach in carbonates

Fast depletion in oil reserves has steered the petroleum industry towards developing novel enhanced oil recovery (EOR) techniques. The standalone EOR methods have associated merits and demerits. For example, the chemical EOR (CEOR) methods have very limited applications in high salinity, high temperature carbonate reservoirs because of increased chemical adsorption and high project costs. In this study, hybrid approaches utilizing engineered water (EW) and CEOR were investigated for carbonate reservoirs. The synergetic effects of EW and chemicals such as polymer, alkali, and surfactant were analyzed. Phase behavior analysis, aqueous stability study, surfactant static adsorption test, and polymer rheological characterization were conducted to select the optimum alkali/surfactant/polymer formulation. To evaluate the increase in oil recovery, wettability alteration, and extent of mobility control, various EW/CEOR combinations were designed for oil displacement experiments, including EW/surfactant flooding (EWSF), EW/polymer flooding (EWPF), EW/surfactant/polymer flooding (EWSPF), and EW/alkali/surfactant/polymer (EWASP) flooding. The EWASP flooding was executed in both continuous and slug-wise injection modes, and the best hybrid EW/CEOR design was selected. 10 times diluted Caspian seawater spiked with optimized active ions was used as the EW. Based on phase behavior and static adsorption tests, 1 wt% Soloterra 113-H was used as a surfactant, while 1 wt% sodium carbonate was used as an alkali. Flopaam 5115 was employed as a polymer with an optimum concentration of 1500 ppm, as established from rheological experiments. The best combination in terms of oil recovery, stability of polymer and surfactant, and chemical consumption was the hybrid EWASP flooding in slug-wise injection mode. This injection scheme resulted in 36% OOIP incremental recovery, 7% higher than the EWPF and EWSPF scenarios and 3% higher than hybrid EWASP flooding in continuous injection mode. Hybrid designs proved to be more effective in recovering residual oil because of better mobility control, reduced capillary trapping, wettability modification, lower surfactant adsorption, and ultra-low interfacial tension (IFT). Our studies showed that the application of hybrid EW/CEOR for carbonate formations, as a novel approach, can expand the application envelope of chemical methods to challenging carbonate formations by making the EOR projects technically and economically viable.

Maxillary Lateral Incisor Injection Pain Using the Dentapen Electronic Syringe

IntroductionWhen patients express fear and anxiety about dentistry, 1 main source involves the administration of local anesthetic. The Dentapen (Septodont, Lancaster, PA) is a computer-controlled local anesthetic device that regulates the rate of anesthetic deposition to reduce pain associated with dental injections. The purpose of this study was to evaluate differences in perceived pain during the administration of local anesthesia of the maxillary lateral incisors using the ramp-up and continuous injection modes of the Dentapen. MethodsThis study used a randomized, controlled, double-blind, crossover, experimental design. The investigators randomly assigned the order of the teeth (#7 or #10) and the 2 delivery modes (continuous or ramp-up). Participants completed a Corah dental anxiety scale at each visit and were injected on 2 separate visits at least 2 weeks apart. After each injection, participants rated their perceived pain using a Heft-Parker visual analog scale at needle insertion, needle placement, and solution deposition. Repeated measures analysis of variance was used to determine differences in perceived pain between the 2 modes. ResultsThe data from 116 participants were analyzed. The perceived pain at deposition with the ramp-up mode (mean = 51.98, standard deviation = 30.04) was less than the continuous mode (mean = 59.98, standard deviation = 36.28) although not statistically significant (F1230 = 2.569, P > .05). Clinically, the perceived pain with the ramp-up mode was in the mild range (<54 mm), whereas the mean perceived pain with the continuous mode was in the moderate/severe range (>54 mm). ConclusionsFurther research should evaluate whether the ramp-up mode could be used to reduce the pain perceived with other dental injections.

Oil recovery and compositional change of CO2 huff-n-puff and continuous injection modes in a variety of dual-permeability tight matrix-fracture models

CO2 offers potential for improving oil recovery of unconventional reservoirs. There is, however, a lack of understanding of mass transport in matrix-facture systems during CO2 injection to simulate hydraulically fractured formations. To bridge the gaps, three dual-permeability tight matrix-fracture models were designed and employed to mimic CO2 huff-n-puff (HnP) and continuous injection (CI). Fracture aperture (h) and fracture permeability (Kf) of the models with confining pressure were firstly correlated, after which CO2 HnP and CI were performed to observe the variations of system pressure (Psys) and oil recovery factor (ORF) over time. Our results indicated that either CO2 HnP or CI could substantially recover the matrix oil, and an ORF up to 53.28% OOIP (original oil in place) was produced by the CI mode. However, the ORF was found to rapidly decline with cycle number or time. The mass transport of these two modes was dictated by both diffusion and advection. Light hydrocarbons (HCs) extraction/vaporization promoted the mass exchange between fracture and matrix, which, therefore, increased the ultimate ORF. Surface area exposure was the decisive factor to the ORF of CO2 injection and other similar methods followed by fluid conductivity. The results of this study supplement earlier findings and can provide insights into the oil recovery mechanisms of CO2 injection in tight reservoirs.

Experimental study on gas EOR for heavy oil in glutenite reservoirs after water flooding

Glutenite reservoirs retain large quantities of residual oil after water flooding. Gas EOR has proven to be an efficient and environmentally friendly method to improve recovery ratios in conventional reservoirs. However, similar experiments carried out on glutenite reservoirs are rare in the literature. Based on PVT analysis, this paper investigates the potential of 4 gas agents (CO2, associated gas, flue gas and deoxygenated air) in the tertiary recovery process. The results show that due to the strong inhomogeneity of glutenite formations, water flooding produces poor recovery ratios, as evidenced by the large amount of oil remained in cores. In the gas EOR stage, in glutenite formations, the WAG strategy is less efficient than the continuous injection approach, which differs from the conventional pattern. Associated gas achieves the greatest increase in oil recovery in the continuous injection mode, with CO2 being the most effective gas agent in the WAG mode. Flue gas and deoxygenated air are more suitable for the huff and puff mode from an economic perspective. Tests also demonstrate that an earlier transition to gas displacement produces more favorable results.

A novel method for highly efficient biotransformation and separation of isoflavone aglycones from soybean with high-speed counter-current chromatography

A novel bioreactor with high-speed counter-current chromatography (HSCCC) was established for the efficient biotransformation of isoflavone aglycones from soybeans. Further, the transformed isoflavone aglycones were separated by HSCCC with continuous injection mode. β-Glucosidase and snailase were chosen as the optimum enzymes for HSCCC bioreactor biotransformation. Compared with snailase, β-glucosidase showed the advantages in both enzymatic hydrolysis efficiency and the influence to retention of the stationary phase and 4 mL/min were selected as the optimum elution flow-rate. The transformed isoflavone aglycones were separated by HSCCC with a solvent system n-hexane/ethyl acetate/ethanol/water (1:1.6:1:1.6, v/v). From 200 mg crude samples, 82 mg of daidzein, 48 mg of glycitein and 24 mg of genistein were separated with purities over 95%, respectively, as determined by HPLC. The chemical structures of these compounds were identified by EI-MS and 1H-NMR. Our results suggest that HSCCC could be developed as a bioreactor in the preparation of isoflavone aglycones from soybeans for the facility to immobilize and recycle the enzyme.

Numerical Simulation of Ion Transport in a Nano-Electrospray Ion Source at Atmospheric Pressure.

Understanding ion transport properties from the ion source to the mass spectrometer (MS) is essential for optimizing device performance. Numerical simulation helps in understanding of ion transport properties and, furthermore, facilitates instrument design. In contrast to previously reported numerical studies, ion transport simulations in a continuous injection mode whilst considering realistic space-charge effects have been carried out. The flow field was solved using Reynolds-averaged Navier-Stokes (RANS) equations, and a particle-in-cell (PIC) method was applied to solve a time-dependent electric field with local charge density. A series of ion transport simulations were carried out at different cone gas flow rates, ion source currents, and capillary voltages. A force evaluation analysis reveals that the electric force, the drag force, and the Brownian force are the three dominant forces acting on the ions. Both the experimental and simulation results indicate that cone gas flow rates of ≤250 slph (standard liter per hour) are important for high ion transmission efficiency, as higher cone gas flow rates reduce the ion signal significantly. The simulation results also show that the ion transmission efficiency reduces exponentially with an increased ion source current. Additionally, the ion loss due to space-charge effects has been found to be predominant at a higher ion source current, a lower capillary voltage, and a stronger cone gas counterflow. The interaction of the ion driving force, ion opposing force, and ion dispersion is discussed to illustrate ion transport mechanism in the ion source at atmospheric pressure. Graphical Abstract.

Comparison of a high temperature torch integrated sample introduction system with a desolvation system for the analysis of microsamples through inductively coupled plasma mass spectrometry

This work describes for the first time the comparison of the analytical performances obtained with a high temperature torch integrated sample introduction system (hTISIS) against those found with a commercially available desolvation system (APEX) associated with inductively coupled plasma mass spectrometry (ICP-MS). A double pass spray chamber was taken as the reference system. Similar detection limits and sensitivities were obtained in continuous injection mode at low liquid flow rates for the APEX and hTISIS operating at high temperatures. In contrast, in the air-segmented injection mode, the detection limits obtained with hTISIS at high temperatures were up to 12 times lower than those found for the APEX. Regarding memory effects, wash out times were shorter in continuous mode and peaks were narrower in air segmented mode for the hTISIS as compared to the APEX. Non spectral interferences (matrix effects) were studied with 10% nitric acid, 2% methanol, for an ICP multielemental solution and a hydro-organic matrix containing 70% (v/v) acetonitrile in water, 15mmolL−1 ammonium acetate and 0.5% formic acid containing lanthanide complexes. In all the cases, matrix effects were less severe for the hTISIS operating at 200°C and the APEX than for the double pass spray chamber. Finally, two spiked reference materials (sea water and Antartic krill) were analyzed. The hTISIS operating at 200°C gave the best results compared to those obtained with the APEX and the double pass spray chamber. In conclusion, despite the simplicity of the hTISIS, it provided, at low liquid flow rates, results similar to or better than those obtained with the by other sample introduction systems.

The Belle II DEPFET pixel detector

The Belle II experiment at KEK (Tsukuba, Japan) will explore heavy flavour physics (B, charm and tau) at the starting of 2018 with unprecedented precision. Charged particles are tracked by a two-layer DEPFET pixel device (PXD), a four-layer silicon strip detector (SVD) and the central drift chamber (CDC). The PXD will consist of two layers at radii of 14mm and 22mm with 8 and 12 ladders, respectively. The pixel sizes will vary, between 50μm×(55–60)μm in the first layer and between 50μm×(70–85)μm in the second layer, to optimize the charge sharing efficiency. These innermost layers have to cope with high background occupancy, high radiation and must have minimal material to reduce multiple scattering. These challenges are met using the DEPFET technology. Each pixel is a FET integrated on a fully depleted silicon bulk. The signal charge collected in the ‘internal gate’ modulates the FET current resulting in a first stage amplification and therefore very low noise. This allows very thin sensors (75μm) reducing the overall material budget of the detector (0.21% X0). Four fold multiplexing of the column parallel readout allows read out a full frame of the pixel matrix in only 20μs while keeping the power consumption low enough for air cooling. Only the active electronics outside the detector acceptance has to be cooled actively with a two phase CO2 system. Furthermore the DEPFET technology offers the unique feature of an electronic shutter which allows the detector to operate efficiently in the continuous injection mode of superKEKB.

Experimental study of gas production from hydrate dissociation with continuous injection mode using a three-dimensional quiescent reactor

The exploitation of methane hydrate formed under the same conditions is simulated experimentally to investigate the gas production behavior at different injected solutions (hot water, saline solution, and ethylene glycol) with continuous injection mode using a three-dimensional quiescent reactor. The influence of hot water temperature, injection rate, and injected solution type on the gas production and the energy efficiency are examined. The results show that the gas production increases with the increased hot water temperature, but the influence of temperature is weakened when it is beyond 313.0K. An optimal injection rate also exists for the gas production. Hydrate dissociation with NaCl solution has the highest gas production compared with Na2SO4 and ethylene glycol when under the same conditions. The comparison of energy efficiency between the continuous injection mode and the interval injection mode shows that the former mode with double wells is more in favor of hydrate dissociation and gas production.

Injection Efficiency Monitor for the Australian Synchrotron

The Australian Synchrotron AS is moving towards a continuous injection mode called top-up. During top-up the linac and booster synchrotron injection system will be in continuous operation rather than usedevery eight hours the way they are used at present. In order to monitor the performance of the injection system areal-time injection efficiency monitoring system has been developed. The system consists of several Fast CurrentTransformers [1] and matching digitisers [2] and is designed to count every beam pulse and measure the transmission efficiency through the whole accelerator complex. After calibrating the system using a properly matchedFaraday Cup at the electron gun, a transmission efficiency is then calculated at each stage of transferring the beamfrom 90 keV out of the gun to 3 GeV in the storage ring. The system is used to optimise the injection process inorder to maximise the injection efficiency and as an early warning system when equipment starts to fail and theinjection efficiency decreases.