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We theoretically investigated the influence of the Casimir effect on mechanical properties of a graphene resonator, where a graphene sheet is located in parallel with a perfectly conducting plate. The Casimir force arising from this effect strongly attracts a graphene sheet to a perfectly conducting plate and increases the tension of a graphene sheet as the separation distance between them decreases. The maximum vertical displacement of a graphene sheet to the substrate increases obeying a power law of a separation distance with an exponent of 4/3 as the separation distance decreases. For small separation distances, the Casimir force is excessively strong for the graphene sheet to maintain a free-standing shape, consequently resulting in the adhesion of the sheet to the substrate below a critical separation distance. The resonant frequency increases over a wide range as the separation distance decreases for large separation distances. However, it then rapidly decreases for small separations and converges to zero at a critical separation. These various behaviors enable the control of a graphene resonator. [ABSTRACT FROM AUTHOR]

Similar phase formation and crystallization behaviors have been observed in the a-Ge/Cu bilayer under thermal annealing and pulsed laser irradiation. The Cu3Ge phase would form prior to the crystallization of a-Ge. The crystallization temperature and activation energy for crystallization of a-Ge were reduced to 310 °C and 2.75 eV, respectively, due to the fast Ge diffusion in the already formed germanide phases. The reaction exponent m of ∼2.0 for the a-Ge/Cu bilayer corresponds to a crystallization process in which grain growth occurs with nucleation, and the nucleation rate decreases with the progress of the grain growth process. Under pulsed laser irradiation, the maximum data-transfer-rates of 44, 56, 74, and 112 Mbit/s can be achieved in the write-once blue-ray disk at the recording powers of 3, 4, 5, and 6 mW, respectively. The a-Ge/Cu bilayer also demonstrated sufficient optical contrast and adequate absorptance for low power and high speed write-once blue-ray recording. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) membranes have great potential in separation technology. However, their instability under aqueous environments hinders their separation performance and practical application. Herein, we present a facile and environmentally friendly method to fabricate stable GO-based membranes via the intercalation of montmorillonite (MMT) nanoplatelets. The as-prepared membranes remain stable under water (neutral, acidic, and alkaline) in a fully hydrated state and exhibit a high pure-water flux up to 139.5 L·m−2·h−1 under 0.09 MPa. Furthermore, they also show high organic molecule rejection (98.75% for Congo red, 99.44% for rhodamine B, 99.90% for crystal violet, 99.94% for methylene blue, 96.26% for phenanthracene, and 51.32% for phenol) as well as good removal rate of heavy metal ions (100% for Ag(I), 100% for Cu(II), and 27.04% for Cr(VI)). Moreover, an outstanding recycling ability of the membranes also has been obtained. These significant performances make our membranes a good candidate in water purification. [ABSTRACT FROM AUTHOR]

Graphical abstract Typical structures of supersonic separator. Highlights • Advances in supersonic separation technology are systematically reviewed. • Condensation models and mathematical methods are generally summed up. • Problems existed in the practical application of the technology are pointed out. • Further research topics and methods to promote future applications are clarified. Abstract Supersonic separation technology is a new approach to condense and separate water, heavy hydrocarbons and other impurities from natural gas. This paper reviews the research advances in condensation characteristics of the Laval nozzle and separation mechanism of the supersonic separator in detail from the perspectives of theoretical analysis, experiments and numerical simulation, and summarizes the new application of this technology including natural gas liquefaction and removal of the acid gases. This review points out that while several aspects of this technology have been well studied, there still exist several issues in the practice. The further research topics are clarified to promote future applications such as the model modification of gas spontaneous nucleation rate to improve the prediction accuracy, and the combination the molecular dynamics technology with interface mechanics theory to study the collision and coalescence of the droplets and the interaction between gas and droplets under supersonic conditions. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Nanocage-like, hollow ZIF-8 (H-ZIF) polyhedral nanocrystals were synthesized. • H-ZIF nanocrystals were distributed in PVC- g -POEM graft copolymer matrix. • Specific interactions between PVC- g -POEM and the imidazole moiety of H-ZIF were observed. • PVC- g -POEM/H-ZIF MMM exhibited an fivefold increase in CO 2 permeability. Abstract Nanocage-like, hollow ZIF-8 (H-ZIF) polyhedral nanocrystals were synthesized via the use of seed crystals, epitaxial ZIF-8 growth, and excavation of ZIF-67 sacrificial templates. The highly porous and hollow structure of the H-ZIF polyhedral nanocrystals was confirmed by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction (XRD), and Brunauer-Emmett-Teller analysis. The H-ZIF nanocrystals were distributed in an amphiphilic poly(vinyl chloride)- g -poly(oxyethylene methacrylate) (PVC- g -POEM) graft copolymer matrix to form mixed-matrix membranes (MMMs) for CO 2 /CH 4 separation. The microphase-separated nature of the structure of the PVC- g -POEM was induced by the solubility difference between the hydrophobic PVC backbone and the hydrophilic POEM side chains. Specific interactions between the micro-structured PVC- g -POEM polymer matrix and the imidazole moiety of the H-ZIF enhanced the interfacial contact and improved the dispersion of the H-ZIF within the MMM; this was confirmed by XRD, FE-SEM, and differential scanning calorimetry. The hollow structure of the H-ZIF reduced the gas diffusion resistance of the MMM, resulting in increased gas permeability. Moreover, the molecular sieving properties and CO 2 -philic amine groups in the imidazole linkers of the H-ZIF led to high CO 2 separation performance. The PVC- g -POEM/H-ZIF MMM exhibited an approximately fivefold increase in CO 2 permeability, with a value of 210.6 barrer, compared to 43.5 barrer for a pristine PVC- g -POEM membrane with a CO 2 /CH 4 selectivity of 14.3, which is close to upper bound reported by Robeson in 2008. [ABSTRACT FROM AUTHOR]

A device for forming an ion beam in a plasma-optic mass separator was developed on the basis of a two-chamber plasma accelerator—thruster—with anodic layers (TAL). The anode of the second chamber in the TAL is replaced with an azimuthator of the mass separator. Functionally, the azimuthator plays the role of the cathode for both the first and second accelerator chambers. This becomes possible after a potential that is negative with respect to the TAL anode is applied to the azimuthator-cathode. The ion source has been tested as a part of the POMS-E-3 mass separator. The ion density at the output of the source is 2-4 times higher than the density at the output of the “classical” two-chamber TAL. [ABSTRACT FROM AUTHOR]

In this paper, an observer-based sliding mode controller is proposed for a high-accuracy motion plant to suppress the disturbances and improve the tracking performance. In particular, a two time-scale separation technology, which can recover the disturbance state in a faster time scale, is utilized to compensate the disturbances and improve the system robustness. The parameter identification is carried out to obtain the model coefficients with a high fitting rate. Such an identified model can allow the engineers to tune the controller's gains highly enough when the system suffers from the measurement noises. Instead of the traditional low-pass filter, a differentiator is introduced for the velocity signal prediction and its discrete-time version is provided to attenuate the noises effect. To verify the effectiveness of the proposed approach, an adaptive robust control law is compared with the proposed one in terms of dynamic positioning error, robustness and rapid signal tracking, and the superiority and advantages can be illustrated by the experimental results. [ABSTRACT FROM AUTHOR]

In order to improve the cleaning effect of filtration system in a pulse-jet cartridge filter, the nozzle area ratio on a semi industrial pulse-jet cartridge filter was studied, using peak pressure and fabric acceleration as indices. Nozzle area ratio, defined as the total area of nozzles/the cross-sectional area of the blow tube. The experimental results show that the cleaning effect of the filter cartridge firstly increases and then decreases with the increase of nozzle area ratio. The optimum nozzle area ratio is 38.72% in this study. Furthermore, the performance of pulse valve will directly affect the influence of the nozzle area ratio on cleaning effect of a pulse-jet cartridge filter. The study also shows that the optimum nozzle area ratio of a pulse-jet cartridge filter and a pulse-jet bag filter are different, and they are verified by experiment and literature in the study. It suggests that the nozzle area ratio of a pulse-jet cartridge filter cannot be designed in accordance with the parameter of a pulse-jet bag filter. [ABSTRACT FROM AUTHOR]

A chemical separation technique for removing interfering gamma-ray radionuclides by combined precipitation of Nb pentoxide and anion exchange was proposed, thereby allowing detection of trace 94 Nb in low-level radwastes. The detection limit for 94 Nb was improved by a factor of 10–10 3 , and the scaling factor ( 94 Nb/ 60 Co) of the radwastes was estimated to be less than 10 −5 . This technique can be used for low-level radwaste classification and power reactor decommissioning. [ABSTRACT FROM AUTHOR]

The solid phase transition pressure swing sorption and the liquid phase complexing sorption integration technology is used to separate paraffin/olefin in the slurry bed reactor. The characterizations of the adsorbents are conducted by the N2 adsorption/desorption, FT-IR, XRD and TG techniques. The effects of different preparation method, a CuCl loaded coefficient and calcination temperature are studied. The results showed that specific surface area and total pore volume of the adsorbents are significantly decreased when compared to those of SiO2 and AC (active carbon). Furthermore, the adsorbents prepared by the impregnation method with SiO2 as carrier, CuCl loaded coefficient of 25.0 wt% and calcinated at 400 °C showed higher separation effects. The propylene/propane selectivity coefficient is reached 2.26, and this implied that the feasibility of adsorbents utilized in slurry bed for paraffin/olefin separation. [ABSTRACT FROM AUTHOR]

A simple separatory glass bottle was used to improve separation effectiveness and cost efficiency while simultaneously creating a simpler system for separating biological compounds. Additionally, it was important to develop a scalable separation method so this would be applicable to both analytical and preparative separations. Compared to conventional foam separation methods, this method easily forms stable dry foam which ensures high purity of yielded fractions. A negatively charged surfactant, sodium dodecyl sulfate (SDS), was used as the ligand to carry a positively charged Rhodamine-G, leaving a negatively charged Evans Blue in the bottle. The performance of the separatory bottle was tested for separating Rhodamine-G from Evans Blue with sample sizes ranged from 1 to 12 mg in preparative separations and 1–20 μg in analytical separations under optimum conditions. These conditions including N 2 gas pressure, spinning speed of contents with a magnetic stirrer, concentration of the ligand, volume of the solvent, and concentration of the sample, were all modified and optimized. Based on the calculations at their peak absorbances, Rhodamine-G and Evans Blue were efficiently separated in times ranging from 1 h to 3 h, depending on sample volume. Optimal conditions were found to be 60 psi N 2 pressure and 2 mM SDS for the affinity ligand. This novel separation method will allow for rapid separation of biological compounds while simultaneously being scalable and cost effective. [ABSTRACT FROM AUTHOR]

The present work aims to develop a model of a new electrochemical CO 2 separation and release technology. We present a one-dimensional transient model of an electrochemical cell for point source CO 2 capture and release, which mainly focuses on the simultaneous mass transport and complex chemical reactions associated with the separation process. For concreteness, we use an ionic liquid (IL) with 2 M thiolate anion (RS − ) in 1 M disulfide (RSSR) as an electrolyte in the electrochemical cell to capture, transport and release CO 2 under standard operating conditions. We computationally solved the model to analyze the time-dependent behavior of CO 2 capture and electro-migration transport across the cell length. Given high nonlinearity of the system, we used a finite element method (FEM) to numerically solve the coupled mass transport equations. The model describes the concentration profiles by taking into account the individual transport of all participating species, charged as well as neutral. The model predicts performance characteristics of electrochemically assisted CO 2 capture and release in terms of faradaic efficiency and cell current density as the cell dynamics evolves and approaches the steady state. The model provides an opportunity to better understand electrochemically assisted CO 2 capture and release, and when coupled with experimental results will provide an early assessment of feasibility for large-scale application in realistic conditions. [ABSTRACT FROM AUTHOR]

Microwave-assisted extraction is compared with a more classical technique, Soxhlet extraction, to determine the content of triterpene acids in olive skins. The samples used in their original unmilled state and milled were extracted with ethyl acetate or methanol as solvents. The optimized operating conditions (e.g., amount and type of solvent, and time and temperature of extractions) to attain the better extraction yields have been established. For the identification and quantitation of the target compounds, an ultra high performance liquid chromatography with tandem mass spectrometry method was employed. The best results were achieved using the microwave-assisted extraction technique, which was much faster than the Soxhlet extraction method, and showed higher efficiency in the extraction of the triterpenic acids (oleanolic and maslinic). [ABSTRACT FROM AUTHOR]

A simulation procedure and results of simulation are reported for the operation of a cascade of packed distillation columns for heavy water deprotiation. The mathematical model is based on the results of laboratory-scale tests of a rolled ribbon-screw structured packing developed at the Mendeleev University of Chemical Technology of Russia an a random spiral prismatic packing made from stainless steel. Use of the rolled ribbon-screw packing in the columns provides means to diminish the volume of the separation equipment without changing the cascade throughput capacity and separation factor. [ABSTRACT FROM AUTHOR]

A common drawback of paper-based separation devices is their poor detection limit. In this study, we combined field-amplified sample stacking with moving reaction boundary electrophoresis on a paper chip with six array channels for the parallel separation and concentration of multiple samples. With a new hyphenated technique, the brown I2 from the Fe3+/I− oxidation-reduction reaction emerged near the boundary between the dilute ethylene diamine tetraacetic acid and potassium iodide and highly concentrated KCl solutions. For the separation and concentration of three components, Cr3+, Cu2+, and Fe3+, the Fe3+ detection limit was improved at least 266-fold by comparing the hyphenated technique with moving reaction boundary electrophoresis. The detection limit of Fe3+ was found to be as low as 0.34 ng (20 μM) on the paper chip. We also demonstrated the analysis of a real sample of four metal ions, with detection limits as follows: 0.16 μg Cr3+, 1.5 μg Ni2+, 0.64 μg Cu2+, and 1.5 μg Co2+. The synergy of field-amplified sample stacking and moving reaction boundary electrophoresis in the micron paper-based array channels dramatically improved the detection limit and throughput of paper-based electrophoresis. [ABSTRACT FROM AUTHOR]

Pure water was used as the eluent for separation of coumarin, vanillin and ethyl vanillin at temperatures ranging from 100 to 200°C using a homemade subcritical water chromatography (SBWC) system. Chromatographic separations were performed on five commercial columns including XTerra MS C18, XBridge C18, Zorbax RRHD Eclipse Plus, Zorbax SB-Phenyl and Zorbax SB-C18 columns. The retention time of all three solutes decreased with increasing water temperature. The shortest retention time among all acceptable separations, less than 4 min, was achieved on the Zorbax SB-C18 column at 200°C. While separations on the XTerra MS C18 column resulted in fronting peaks and a degradation peak from ethyl vanillin on the Zorbax RRHD Eclipse Plus column was observed, all three other columns yielded reasonable separations under SBWC conditions. In addition to separation of the standard test mixture, separation of coumarin contained in a skincare cream sample was also carried out using SBWC. [ABSTRACT FROM AUTHOR]

A methylene blue (MB) dye pollutant was separated by SBA-15 for the first time in fixed-bed continuous systems. The continuous adsorption experiments were included: the effect of bed height, flow rate and initial concentration on breakthrough curve investigation. Breakthrough performance showed SBA-15 has the most promise for application in continuous adsorption systems. The results illustrate that MB capture is obtained at the maximum uptake (83.6 mg/g) when the bed height was (6 cm), initial concentration (40mg/L) and flow rate (0.6mL/min). The mesoporous SBA-15 was recovered effectively by calcinations and employed again for five times in continuous system successfully. [ABSTRACT FROM AUTHOR]

The purification of a complex feed stream of a multicomponent product, i.e., two isomers and impurities, by melt crystallization was evaluated by studying different optimization parameters like crystal growth rate, crystallization time, and purity. First, a phase diagram was established and on this basis different crystallization experiments were carried out. A laboratory-scale solid layer melt crystallizer, a so-called cold finger, was used to determine the purity and separation of the components, i.e., the ratio of the components, from the product at different crystallization times and temperatures as a function of layer thickness and a sweating process. The desired composition of the final product was achieved by adding components resulting from the second stage of crystallization since the first crystallization gave only the desired purity but not the right mixture of the two compounds of the wanted product. [ABSTRACT FROM AUTHOR]

We extend the classical J-integral approach to calculate the energy release rate of cracks by prolonging the contour path of integration across a traction-transmitting interphase that accounts for various phenomena occurring within the gap region defined by the nominal crack surfaces. Illustrative examples show how the closed contours, together with a proper definition of the energy momentum tensor, account for the energy dissipation associated with material separation. For cracks surfaces subjected to cohesive forces, the procedure directly establishes an energetic balance a la Griffith. For cracks modeled as phase-fields, for which no neat material separation occurs, integration of a generalized energy momentum (GEM) tensor along the closed contour path that traverses the damaged material permits the calculation of the energy release rate and the residual elasticity of the completely damaged material. [ABSTRACT FROM AUTHOR]

This article draws, with a simplified but rigorous approach, the typical procedure for the design and optimization of functional multicomponent structures for light to chemical energy conversion for two series of multipartite structures based on prototypical chromophores: polypyridyl metal complexes and porphyrinoids. Starting from a photophysical study performed by steady-state and time-resolved spectroscopic methods, the full deactivation dynamics of the light-absorbing chromophore(s) are disclosed. The preferred deactivation step (electron transfer in this case) is then optimized. This can be done by simply operating on the solvent, but also by changing structure/components that can alter electronic and nuclear factors, via continuous feedback with the research groups in charge of the synthesis. With a presentation suitable for a wide audience, it is here discussed how the effective design of functional multicomponent structures for charge separation can be achieved. [ABSTRACT FROM AUTHOR]

A complete review of the published data on the mixing enthalpies of mixtures containing ionic liquids, measured directly using calorimetric techniques, is presented in this paper. The field of ionic liquids is very active and a number of research groups in the world are dealing with different applications of these fluids in the fields of chemistry, chemical engineering, energy, gas storage and separation or materials science. In all these fields, the knowledge of the energetics of mixing is capital both to understand the interactions between these fluids and the different substrates and also to establish the energy and environmental cost of possible applications. Due to the relative novelty of the field, the published data is sometimes controversial and recent reviews are fragmentary and do not represent a set of reliable data. This fact can be attributed to different reasons: (i) difficulties in controlling the purity and stability of the ionic liquid samples; (ii) availability of accurate experimental techniques, appropriate for the measurement of viscous, charged, complex fluids; and (iii) choice of an appropriate clear thermodynamic formalism to be used by an interdisciplinary scientific community. In this paper, we address all these points and propose a critical review of the published data, advise on the most appropriate apparatus and experimental procedure to measure this type of physical-chemical data in ionic liquids as well as the way to treat the information obtained by an appropriate thermodynamic formalism. [ABSTRACT FROM AUTHOR]

This paper illustrates opportunities provided by the method of stepwise crushing for the investigation of the fluid phase of geologic objects. Owing to the efficient separation of gases from fluid inclusions of different generations trapped during mineral growth and/or subsequent alteration (metasomatic and hydrothermal), stepwise crushing allows us to obtain the isotopic characteristics of end-members and, thus, reliably establish the source and evolution of fluids in magmatic and postmagmatic processes; this method provides clues to a better understanding of interaction of global reservoirs, such as the mantle, crust, and atmosphere. The importance of information obtained by this method is exemplified here by the results of the investigation of mantle rocks and minerals from various geologic environments (MORB, SCLM, and carbonated mantle). It was shown that the multi-isotope approach yields most comprehensive data on the genetic features and evolution of the fluid phase. The importance of combining isotope geochemical and microthermometric fluid inclusion data is demonstrated by the example of a mantle xenolith of garnet lherzolite from the Jetty Oasis. Together with the microthermometric investigation of fluid inclusions and developing laser techniques for opening of individual inclusions, the method of stepwise crushing provides a means for solving one of the most important practical problems-obtaining information on the geochemical features and physicochemical parameters of mineral-forming (and ore-forming) processes. [ABSTRACT FROM AUTHOR]

The distillation based separation can be extremely complex if highly non-ideal mixtures are to be separated. In spite of different successfully applied unit operations there is still a possible way to improve the distillation technique and widen its toolbar. A new improvement in this area is the development of the extractive heterogeneous-azeotropic distillation (EHAD). This unit operation includes the merits of extractive- and heterogeneous-azeotropic distillations in one unit without extra material addition. Our work supports EHAD features with successful experiments compared with modelling and comparison with other separation structures proving that the application of EHAD makes the separation of extremely non-ideal mixtures possible on an easy, powerful, energy saving, and cost efficient way. [ABSTRACT FROM PUBLISHER]

Herein, porous Bi/Bi2MoO6 nanoparticles have been prepared by a facile in-situ reduction approach. Moreover, the morphology and Bi content of product could be controlled by varying the reaction time. By controlled fabrication, the desired porous Bi2MoO6 nanostructure with incorporation of Bi was obtained and exhibited high photoelectric and photocatalytic activity. In particular, the samples yield a photocurrent density of 320 μA cm−2, which is 3.2 times that of the pure Bi2MoO6 nanosheet (100 μA cm−2) under the same conditions. UV/Vis diffuse reflectance spectroscopy analysis confirmed the surface plasmon resonance in the as-prepared porous nanoparticles. The improved photoelectric properties could be the synergistic effect of the porous structure with large surface area and effective electron-hole separations between Bi and Bi2MoO6. [ABSTRACT FROM AUTHOR]

Evolution of pure hydrogen and oxygen by photocatalytic water splitting was attained from the opposite sides of a composite Pt/Ti/TiO2 photoelectrode. The TiO2 films were prepared by radio frequency (RF)-Magnetron Sputtering at different deposition time ranging from 1 up to 8 h and then characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet-visible-near infrared (UV-vis-NIR) diffuse reflectance spectroscopy. The photocatalytic activity was evaluated by incident photon to current efficiency (IPCE) measurements and by photocatalytic water splitting measurements in a two-compartment cell. The highest H2 production rate was attained with the photoelectrode prepared by 6 h-long TiO2 deposition thanks to its high content in the rutile polymorph, which is active under visible light. By contrast, the photoactivity dropped for longer deposition time, because of the increased probability of electron-hole recombination due to the longer electron transfer path. [ABSTRACT FROM AUTHOR]

Raman spectroscopy at high temperature has been applied to study in situ the microstructure of the solution in a Cs2O-B2O3-MoO3 growth system. A crystal-solution interface was observed. The BO groups consist of spiral chains based on B3O4Ø2 rings in the solution (Ø is a bridging O atom). The Raman spectrum of the solution indicates that MoO4 tetrahedra existed in the growth system. The nonbridging O atoms of the chains combined with the MoO4 groups, which decreased the viscosity. The Raman spectra near the interface show that at the boundary an isomerization reaction from three- to four-coordinated boron occurred. The formation of B3Ø7 triborate groups occurred. The morphology of the CsB3O5 crystal resulting from spontaneous crystallization was observed to correspond to our expectations. [ABSTRACT FROM AUTHOR]

High-performance liquid chromatography analysis of vonoprazan fumarate, a novel proton pump inhibitor drug revealed six impurities. These were identified by liquid chromatography with mass spectrometry. Further, the structures of the impurities were confirmed by synthesis followed by characterization by mass spectrometry, NMR spectroscopy, and infrared spectroscopy. On the basis of these data and knowledge of the synthetic scheme of vonoprazan fumarate, the previously unknown impurity was identified as 1-[5-(2-fluorophenyl)-1-(pyridin-3-ylsulfonyl)-1 H-pyrrol-3-yl]- N-methyldimethylamine, which is a new compound. The possible mechanisms by which these impurities were formed were also discussed. A high-performance liquid chromatography method was optimized in order to separate, selectively detect, and quantify all process-related impurities of vonoprazan fumarate. The presented method has been validated in terms of linearity, limits of detection, and quantification, and response factors and, therefore, is highly suitable for routine analysis of vonoprazan fumarate related substances as well as stability studies. [ABSTRACT FROM AUTHOR]

In this work a membrane-based process for the fractionation of artichoke brines was investigated in order to separate flavonoids and caffeoylquinic acids from salt compounds. Therefore, the performance of different spiral-wound nanofiltration (NF) membranes in the treatment of clarified artichoke brines was evaluated in terms of productivity and selectivity towards bioactive compounds in selected operating conditions. Membranes with different polymeric material (polyethersulphone, polyammide) and molecular weight cut-off (MWCO) (from 200 to 1000 Da) were tested. NF membranes of 200 Da produced better results in terms of recovery and concentration of compounds of interest. A better separation of salt compounds from caffeoylquinic acid derivatives was reached by using Filmtec-Dow NF 200 and Desal DL membranes. For these membranes a low rejection towards dry residue (between 14% and 18%) was observed, while rejections towards total caffeoylquinic acids, flavonoids and cynarin were higher than 92%. According to the obtained results the NF permeate, enriched in salt compounds, can be reused in the working cycle for the preparation of new acidulated brines through the adjustment of the standard salt concentration; the concentrated stream, enriched in phenolic compounds, is a good source of possible ingredients to functionalize foodstuffs. [ABSTRACT FROM AUTHOR]

For trace impurity measurements in uranium, the matrix is expected to be removed prior to analysis, usually achieved by offline separation methods involving relatively large amounts of radioactive samples. Herein, a novel online method is developed for impurity separation and measurements by interfacing microfluidics and ICP-MS. In this method, the uranium matrix is removed via micro-extraction in parallel two-layer laminar flow (PTL) microfluidics, and the remaining impurities in the aqueous phase are directly analyzed by ICP-MS. The separation efficiency and the analytical performance of this method are evaluated, and the method is validated using both the certified reference material (CRM) and the real sample. Such an online PTL-ICP-MS method features less radioactive waste and lowers the risk of exposure to radioactive materials. [ABSTRACT FROM AUTHOR]

The method described in this study is a robust and sensitive method for the simultaneous determination of trivalent and hexavalent chromium (Cr(iii) and Cr(vi)) in an exhaled breath condensate (EBC) sample and drinking water proficiency testing material sample. The method uses a hyphenated micro liquid chromatography (μLC) system coupled to inductively coupled plasma mass spectrometry (ICP-MS). The optimised method incorporates a pH adjusted EDTA complexation step to stabilise Cr(vi) and Cr(iii). Separation was achieved using an anion exchange micro-sized column. The limits of quantification were 0.040 μg L−1 and 0.013 μg L−1 for Cr(iii) and Cr(vi) respectively. EBC is the non-invasive collection of condensate from cooled exhaled breath during regular tidal breathing. We propose that EBC may be a suitable alternative biological matrix to give a more comprehensive picture of exposure to Cr(vi) following an inhalation exposure. This study shows that water samples and EBC samples containing Cr(iii) and Cr(vi) can be stored in the fridge (∼4 °C) for up to 6 weeks when they have been diluted 10 fold with an EDTA solution, and that EBC samples must not be frozen after collection if the integrity of Cr(vi) is to be maintained. This study has demonstrated a practical approach to collecting EBC samples from workers potentially occupationally exposed to hexavalent chromium and that the integrity of the chromium species will be maintained prior to analysis. [ABSTRACT FROM AUTHOR]

In this article, chlorosilane-modified ZSM-5 particles were incorporated into polydimethylsiloxane (PDMS) to form mixed matrix membranes (MMMs) for ethanol/water mixture separation via pervaporation (PV). The membranes were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and mechanical performance testing. The maximum loading and dispersion of ZSM-5 into PDMS were improved by chlorosilane modification. To evaluate the PV performance, the MMMs were used to separate an aqueous ethanol solution. The effect of zeolite loading and operational conditions on PV performance was investigated in detail. The separation factor of the composite membranes filled with modified ZSM-5 increased considerably versus unmodified membrane, while the total flux decreased to some degree. Of all the chlorosilane-modified membranes, dodecyltrichlorosilane modified ZSM-5 filled PDMS showed the best separation factor of 15.8 for ethanol. [ABSTRACT FROM AUTHOR]

A major challenge in metabolomic studies is how to extract and analyze an entire metabolome. So far, no single method was able to clearly complete this task in an efficient and reproducible way. In this work we proposed a sequential strategy for the extraction and chromatographic separation of metabolites from leaves Jatropha gossypifolia using a design of experiments and partial least square model. The effect of 14 different solvents on extraction process was evaluated and an optimized separation condition on liquid chromatography was estimated considering mobile phase composition and analysis time. The initial conditions of extraction using methanol and separation in 30 min between 5 and 100% water/methanol (1:1 v/v) with 0.1% of acetic acid, 20 μL sample volume, 3.0 mL min−1 flow rate and 25°C column temperature led to 107 chromatographic peaks. After the optimization strategy using i-propanol/chloroform (1:1 v/v) for extraction, linear gradient elution of 60 min between 5 and 100% water/(acetonitrile/methanol 68:32 v/v with 0.1% of acetic acid), 30 μL sample volume, 2.0 mL min−1 flow rate, and 30°C column temperature, we detected 140 chromatographic peaks, 30.84% more peaks compared to initial method. This is a reliable strategy using a limited number of experiments for metabolomics protocols. [ABSTRACT FROM AUTHOR]

Hindered amine light stabilizers are an important class of stabilizers that protect synthetic polymers from degradation and thus from changing mechanical and optical properties. The current study presents an HPLC method capable of separating oligomeric hindered amine light stabilizers on a commercially available stationary phase, employing an MS-compatible novel mobile phase. Based on the exact masses observed with Q-TOF-MS, a comprehensive characterization of five different types of oligomeric hindered amine light stabilizers was achieved, leading to structural information not included in the datasheets provided by the suppliers. For the different investigated hindered amine light stabilizers, a number of recurring units up to 17 and a molecular weight of 5200 g/mol were detected. Furthermore, the analysis of stabilizer extracts of processed polypropylene samples containing different types of hindered amine light stabilizers revealed significant differences in the oligomeric pattern between standards and polymer samples. Thus, changes in the analytes' oligomeric pattern resulting from processing or aging of polymer materials can be monitored with the presented method. [ABSTRACT FROM AUTHOR]

An ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction was first employed to determine the volatile components in tobacco samples. The method combined the advantages of ultrasound, microwave, and headspace solid-phase microextraction. The extraction, separation, and enrichment were performed in a single step, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, several experimental parameters, such as fiber type, ultrasound power, and irradiation time, were optimized to improve sampling efficiency. Under the optimal conditions, there were 37, 36, 34, and 36 components identified in tobacco from Guizhou, Hunan, Yunnan, and Zimbabwe, respectively, including esters, heterocycles, alkanes, ketones, terpenoids, acids, phenols, and alcohols. The compound types were roughly the same while the contents were varied from different origins due to the disparity of their growing conditions, such as soil, water, and climate. In addition, the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method was compared with the microwave-assisted extraction coupled to headspace solid-phase microextraction and headspace solid-phase microextraction methods. More types of volatile components were obtained by using the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method, moreover, the contents were high. The results indicated that the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction technique was a simple, time-saving and highly efficient approach, which was especially suitable for analysis of the volatile components in tobacco. [ABSTRACT FROM AUTHOR]

The separation of basic macrolide antibiotics suffers from peak tailing and poor efficiency on traditional silica-based reversed-phase liquid chromatography columns. In this work, a C18HCE column with positively charged surface was applied to the separation of macrolides. Compared with an Acquity BEH C18 column, the C18HCE column exhibited superior performance in the aspect of peak shape and separation efficiency. The screening of mobile phase additives including formic acid, acetic acid and ammonium formate indicated that formic acid was preferable for providing symmetrical peak shapes. Moreover, the influence of formic acid content was investigated. Analysis speed and mass spectrometry compatibility were also taken into account when optimizing the separation conditions for liquid chromatography coupled with tandem mass spectrometry. The developed method was successfully utilized for the determination of macrolide residues in a honey sample. Azithromycin was chosen as the internal standard for the quantitation of spiramycin and tilmicosin, while roxithromycin was used for erythromycin, tylosin, clarithromycin, josamycin and acetylisovaleryltylosin. Good correlation coefficients ( r2 > 0.9938) for all macrolides were obtained. The intra-day and inter-day recoveries were 73.7-134.7% and 80.7-119.7% with relative standard deviations of 2.5-8.0% and 3.9-16.1%, respectively. Outstanding sensitivity with limits of quantitation (S/N ≥ 10) of 0.02-1 μg/kg and limits of detection (S/N ≥ 3) of 0.01-0.5 μg/kg were achieved. [ABSTRACT FROM AUTHOR]

Protamines are a group of highly basic peptides that are sometimes added to insulin formulations to prolong the pharmacological action. In this study, different methods were investigated to identify protamine in insulin formulations. Capillary electrophoresis in aqueous and non-aqueous media was tested to separate these peptides with very close amino acid sequences. Different buffers (phosphate or formate, both acidified) and various additives (principally negatively charged and neutral surfactants) were investigated to optimize peptide separation. Finally, a micellar electrokinetic capillary chromatography method using a capillary of 120 cm effective length and an aqueous background electrolyte made up of 100 mM phosphate buffer (pH 2) and 50 mM Thesit® gave the best results, providing the separation of the four major protamine peptides within 25 min. [ABSTRACT FROM AUTHOR]

Disposable pipette tips extraction consists of a solid-phase extraction in which the sorbent is poorly dispersed in a pipette tip, which allows a quick and dynamic contact between the aspirated analyte from the sample and the solid phase. It is a technique used particularly in food and forensic analysis, since it requires a small amount of sample and solvent. This article highlights the principles, advantages and disadvantages of the disposable pipette tips extraction method and reviews recent applications. [ABSTRACT FROM AUTHOR]

Cyclodextrins and their derivatives are one of the most common and successful chiral selectors. However, there have been few publications about the use of cyclodextrin-modified monoliths. In this study, organic hybrid monoliths were prepared by the immobilization of derivatized β-cyclodextrin alone or with l-2-allylglycine hydrochloride to the polyhedral oligomeric silsesquioxane methacryl substituted monolith. The main topic of this study is a combined system with dual chiral selectors ( l-2-allylglycine hydrochloride and β-cyclodextrin) as monolithic chiral stationary phase. The effect of l-2-allylglycine hydrochloride concentration on enantioseparation was investigated. The enantioseparation of the four acidic compounds with resolutions up to 2.87 was achieved within 2.5 min on the prepared chiral monolithic column in capillary liquid chromatography. Moreover, the possible mechanism of enantioseparation was discussed. [ABSTRACT FROM AUTHOR]

Daidzin, genistin, and glycitein are major isoflavone compounds in soybean that are indispensable nutrients in traditional Chinese foods. Generally, strategies for detecting and separating soy isoflavones have been based on HPLC and chromatographic techniques, which are tedious and time-consuming procedures. In the present study, we developed an ELISA-based approach for daidzin detection using a broad-specificity monoclonal antibody (clone number: AA9) with an effective detection range of 10-10 000 ng/mL. Subsequently, we prepared an immunoaffinity column by coupling the monoclonal antibody AA9 to CNBr-activated Sepharose 4B. Our results demonstrate that the immunoaffinity column can efficiently and specifically extract daidzin, glycitein, and genistin from numerous structurally similar soy isoflavones in leguminous plants, thereby providing a new method for the extraction of target components from similar compounds in natural products. [ABSTRACT FROM AUTHOR]

The global crisis resulting from adulterated heparin in late 2007 and early 2008 revived the importance of analytical techniques for the purity analysis of heparin products. The utilization of ion chromatography techniques for the separation, detection, and structural determination of heparin and structurally related glycoaminoglycans, including their corresponding oligosaccharides, has become increasingly important. This review summarizes the primary HPLC approaches, particularly strong anion exchange, weak ion exchange, and reversed-phase ion-pair, used for heparin purity analysis as well as structural characterization. Strong anion exchange HPLC has been studied most extensively and currently offers the best separation of crude heparin and heparin-like compounds. Weak anion exchange HPLC has been shown to provide shorter analysis times with lower salt concentrations in the mobile phase but is not as widely developed for the separation of all glycoaminoglycans of interest. Reversed-phase ion-pair HPLC offers fast and effective separations of oligosaccharides derived from glycoaminoglycans that can be coupled to mass spectrometry for structural analysis. However, this method generally does not provide sufficient retention of intact glycoaminoglycans. [ABSTRACT FROM AUTHOR]

Distance-of-flight mass spectrometry (DOFMS) is demonstrated for the first time with a commercially available ion detector-the IonCCD camera. Because DOFMS is a velocity-based MS technique that provides spatially dispersive, simultaneous mass spectrometry, a position-sensitive ion detector is needed for mass-spectral collection. The IonCCD camera is a 5.1-cm long, 1-D array that is capable of simultaneous, multichannel ion detection along a focal plane, which makes it an attractive option for DOFMS. In the current study, the IonCCD camera is evaluated for DOFMS with an inductively coupled plasma (ICP) ionization source over a relatively short field-free mass-separation distance of 25.3-30.4 cm. The combination of ICP-DOFMS and the IonCCD detector results in a mass-spectral resolving power (FWHM) of approximately 900 and isotope-ratio precision equivalent to or slightly better than current ICP-TOFMS systems. The measured isotope-ratio precision in % relative standard deviation (%RSD) was ≥0.008%RSD for nonconsecutive isotopes at 10-ppm concentration (near the ion-signal saturation point) and ≥0.02%RSD for all isotopes at 1-ppm. Results of DOFMS with the IonCCD camera are also compared with those of two previously characterized detection setups. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Prediction of chromatographic separations in liter scale with the help of data gathered using a microliter format is challenging, as both scale effects and differences in the formats used (plates vs. packed minicolumns) need to be addressed. The use of microplates in high-throughput process development (HTPD) studies has become a routine. While this method is typically used for investigating chromatography conditions such as salt and pH, it can also be used for screening of different chromatography media (resins). In this study, the influence of the physicochemical properties of various media on preparation of medium-containing microplates is discussed, and examples are presented that show how these properties can influence the conclusions drawn in benchmarking studies done using this HTPD format. The results indicate that differences in chromatographic media volume between microliter sampling techniques and packed chromatography columns do exist. Regardless of the chosen chromatography media, sampling technique or volume definition method, the simplest way to address this issue is by calibrating the microliter scale with packed-column volumes in appropriate dry weight experiments. [ABSTRACT FROM AUTHOR]

Static electric fields are used, among others, in technological processes such as electric separation. Electrodynamic separation is a process of separating two or more solid phases of various physical properties by electric field forces. The advantage of electrodynamic separation is possibility of obtaining separation of individual components in dry conditions. This eliminates many operations such as thickening, dewatering, hydrotransportation, additional drying which cause higher energy consumption and higher separation process costs. Efficiency of beneficiation depends on many factors such as: electric properties of feed components, feed particle size distribution, drum rotary speed, electric field intensity in working space of separator, configuration of electrodes or surrounding conditions. The paper presents the working of high-voltage drum separator. The analysis of electric field distribution in separator working space was done. Additionally, distribution of forces acting on particles of dielectric and conductive properties was examined, trajectories of charged particles movement were presented too. The laboratory investigations of electronic wastes were performed in two particle fractions: 0.25-0.5 mm and 0-0.25 mm. It was observed that as a result of selective charging of particles they separate according to surface ability to electrifying what allows to obtain selective separation of components being so-called electronic wastes. The application of electrodynamic drum separator allows to separate such elements as Ti, Cu, Fe, Pb, Sn from plastics occurring in electronic wastes. [ABSTRACT FROM AUTHOR]

It is always stated that cakes formed under centrifugal fields have lower cake permeability than the cakes formed under gas pressure difference, but systematical investigations have not yet been published. Results are reported for two different suspensions from experiments carried out with both techniques under identical suspension conditions. A new standardized analysis method supported by cake flow-through experiments is explained and allows the plotting of all results in the same diagram. For both suspensions, and contrary to the common belief, significantly higher cake permeability values for the laboratory centrifuge tests were determined. Explanations for this behavior are given. [ABSTRACT FROM AUTHOR]

The separation of liquid-gas flows is essential for many industrial processes. Computational fluid dynamics including the algebraic slip mixture model and the Reynolds stress model is firstly adopted to analyze the impact of the number of inlets and the column diameter ratio on the degassing performance of a hydrocyclone. For separating the micrometer-sized bubbles, the structures with one to six inlets and seven different column diameter ratios are simulated. The results show that multiport designs are more suitable for liquid-gas separation, particularly for separation of small bubbles. However, as the number of inlets increases, the growth trend of separation efficiency is slowed. A longer column section is beneficial to small bubbles, but results in a greater loss of fluid energy. [ABSTRACT FROM AUTHOR]

A new mechanistic model for filter-aid filtration with incompressible cakes is presented. Surface- and depth-filtration effects are considered based on a continuum mechanics approach. This leads to a moving boundary problem with sharp moving fronts. Proper mathematical and numerical methods for its solution are identified which allow fully transient simulations concerning all process variables and parameters. All relevant physical phenomena known from experimental studies are captured by the model, some of them for the first time. In two case studies, the effects of changing the filter-aid particle diameter at a discrete time point and continuously varying the amount of filter aid with time are considered. Significant influences on the separation efficiency, the local deposit profile within the filter cake, and the overall pressure drop are found. [ABSTRACT FROM AUTHOR]