Combined Analytical Method Research Articles

Mass spectrometry-based analytical developments to link iron speciation to iron bioavailability in maize

A sequential fractionation procedure based on (i) water extraction, (ii) hexane extraction, (iii) saccharification, and (iv) proteolysis was developed to provide the first ever data on the molecular distribution of iron in maize. This was completed by the operational determination of the iron bioavailability using an in-vitro simulated model for gastro-intestinal digestion. The coupling of hydrophilic interaction chromatography (HILIC) and size exclusion chromatography (SEC) with the parallel detection by inductively coupled plasma mass spectrometry (ICP-MS) and high resolution electrospray mass spectrometry (HR-ESI-MS) allowed the identification of water-soluble Fe(III)-mugineate, Fe(III)-(citrate)2, and Fe(III)2-(phytate)2. The procedures were applied to study some well characterized maize varieties having shown previously differences in iron bioavailability during cell culture and animal model feeding studies. The combined analytical methods developed in this work could unambiguously discriminate low from high Fe bioavailable seeds in these closely related maize varieties.

Magnetic nanocomposites: versatile tool for the combination of immunomagnetic separation with flow-based chemiluminescence immunochip for rapid biosensing of Staphylococcal enterotoxin B in milk.

Immunomagnetic separation (IMS) was combined with flow-based chemiluminescence sandwich immunoassays (CL-SIA) for the quantification of Staphylococcal enterotoxin B in milk. Therefore, iron oxide-shell silica-core magnetic nanocomposites were conjugated to biotinylated anti-SEB antibodies (MNC-IgGs). MNC-IgGs were applied successfully for (i) capturing SEB in milk samples by an affinity reaction, (ii) magnetophoretic collection on antibody spots in a channel of a flow-based immunochip, and (iii) sensitive enzymatic chemiluminescence detection of biotin labels by poly(horseradish peroxidase)-streptavidin. IMS was performed in 0.6mL and 100mL milk samples resulting in detection limits of 50ngL-1 and 0.39ngL-1, respectively, for the combined analytical method. It was shown that the assay sensitivity was dramatically improved by the combination of IMS with flow-based CL-SIA compared to CL-SIA directly applied with milk samples (detection limit 130ngL-1). The IMS-CL-SIA has a time-to-result of 2-3h. The reported combined analytical method can be used for a rapid control of SEB in complex food matrices such as milk. In future, even the monitoring of multiple contaminants in food or water may be performed by IMS-CL-SIA. Graphical abstract.

Investment risk assessment of coal-fired power plants in countries along the Belt and Road initiative based on ANP-Entropy-TODIM method

Coal is an irreplaceable part of the world energy structure and the condition will not be changed in the near future. Under the Belt and Road initiative, more and more Chinese energy enterprises are planning to invest in coal-fired power plant (CFPP) abroad. However, there are multiple potential risks in investing in CFPP overseas. So, assessing the risk level can help the investors avoid too risky countries and at the same time facilitate the government to take measures to reduce the potential risks to attract more investors. To reasonably assess overseas investment risk of CFPP in countries along the Belt and Road initiative, this paper establishes an evaluation criteria system from eight dimensions which consists of a total of 39 criteria. Then, these criteria weights are determined through a combined analytic network process-Entropy method. Furthermore, considering the psychological characteristics of decision-makers, a TODIM (an acronym in Portuguese for Interactive Multi-criteria Decision Making) approach is used to rank the overall risk level of CFPP investment for 23 nations. The findings indicate that the criterion of economic foundation owns the largest weight. Moreover, among these evaluated nations, Singapore have the lowest risk for China’s CFPP investment, followed by New Zealand and Thailand.

A combined analytical method for biological monitoring of arsenic, benzene and polycyclic aromatic hydrocarbons in human urine by liquid chromatography tandem mass spectrometry

An analytical method for the biomonitoring of arsenic, benzene and polycyclic aromatic hydrocarbons (PAHs) in human urine was developed using liquid chromatography tandem mass spectrometry (LC-MS/MS). The urinary metabolites of monomethylarsonic acid (MMAA), dimethylarsonic acid (DMAA), s-phenylmercapturic acid (S-PMA), and 1-hydroxypyrene (1-OHP) were selected as the corresponding marker compounds. After enzymatic deconjugation, 4 mL urine sample was extracted by 2 steps of solvent extractions. The 1-OHP was first extracted with n-hexane with 10% ethyl acetate, and MMAA, DMMA, and S-PMA were then extracted in a 2nd extraction/back-extraction using chloroform/ammonium bicarbonate aqueous solution. The two extracts were mixed and analyzed by LC-MS/MS. The method was validated with spiked urine samples. The obtained linear ranges (r2 > 0.99) of the urinary markers were 2–64 ng/mL MMAA, 1–64 ng/mL DMAA, 0.78–100 ng/mL S-PMA and 0.05–6.4 ng/mL 1-OHP. The measured accuracy (% Error) and precision (CV%) were -16.67 to 29.17% and 2.03–30.99% (3 spiked levels, 6 replicates), respectively. The method was applied to 10 real urine samples, and the presence of MMAA, DMAA, S-PMA and 1-OHP were clearly detected. The detected concentrations were BQL-8.38 ng/mL of MMAA, BQL-10.71 ng/mL of DMAA, BQL-2.55 ng/mL of SPMA, and BQL-0.17 ng/mL of 1-OHP, which were all consistent with the reported background levels.

Evaluation of electronic state of Cs-adsorbed clay minerals by NEXAFS analysis using DFT calculations

A combined analytical method of NEXAFS measurement and DFT-calculation was employed for the evaluation of Cs states in clay minerals. The measured Cs M4,5 NEXAFS spectra of Cs halides were analyzed using the DFT-calculations in order to establish the analytical methods. The NEXAFS spectra of the Cs halides were well reproduced by incorporating the core-hole strength. The Cs M4,5 NEXAFS spectrum of the clay minerals was well reproduced by the DFT-calculations including the major transitions and tail structures with the established method. Further evaluation of this spectrum by charge density analysis suggested that these major transitions and the tail structures likely reflect the bonding state and the local environment around the Cs atoms. Comparison of electronic states of Cs in the clay mineral with those in the Cs halides by DFT-calculations has shown that the interaction between Cs and the nearest-neighbor atom is largest in the clay mineral, which differs from those of Cs halides. This happened due to the energy level of Cs-5s and 5p, which was closer to that of O-2s and 2p than the s and p orbitals of other alkali metal and alkali earth metal elements.

An analytical-numerical approach in the calculation of photovoltaic module parameters operating under partial shaded conditions

The aim of this work is to determine the parameters and characteristics of a PV module in case of partial shading conditions. Both numerical and analytical methods are used in order to attain this objective. The iterative method namely Newton-Raphson is used to evaluate the characteristics of the PV module under partial shading conditions at its peak point. For various shading conditions, the lost power by the module is evaluated in order to show the influence of the partial shading conditions. The combined analytic method with the iterative method used allowed fairly accurate results on the behaviour of the shaded PV modules with less difficulties compared to the analytical method alone.

Effect of the aspect ratio on the flow characteristics of magnetohydrodynamic (MHD) third grade fluid flow through a rectangular channel

The magnetohydrodynamic (MHD) flow of a third grade fluid through a rectangular channel, considering the effect of aspect ratio, has been investigated. The flow considered is steady, laminar, incompressible and hydro-dynamically fully developed. The equation, describing the flow, is a highly non-linear partial differential equation (PDE) with remote possibility of having an exact solution and even numerical solution also is very difficult to obtain. A combination of the homotopy perturbation method (HPM) and integral method (IM) has been employed to solve the non-linear PDE which is scarce in open literature. The results of the present study are compared with the results obtained by the least square method (LSM) of the MHD third grade fluid flow through a rectangular channel, without the effect of aspect ratio and are found to be in close agreement. The results indicate that the flow field is significantly affected by the aspect ratio which should be considered for practical applications. In all the available literatures of the third grade fluid flow, the aspect ratio effect is neglected and this simplifying assumption reduces the highly complicated non-linear PDE to a non-linear ordinary differential equation (ODE). The novelty of the subject work lies in the inclusion of the effects of aspect ratio in the governing equation describing the flow of a third grade fluid through a channel and solving this by a combined analytical method (HPM and IM). Further, the effects of the Hartmann number and non-Newtonian third grade fluid parameter on the flow filed are discussed.

Transmission Electron Microscopy Reveals Deposition of Metal Oxide Coatings onto Metal-Organic Frameworks.

Postsynthetic strategies for modifying metal-organic frameworks (MOFs) have proven to be an incredibly powerful approach for expanding the scope and functionality of these materials. Previously, we reported on the postsynthetic exchange (PSE) of metal ions and ligands in the University of Oslo (UiO) series of MOFs. Detailed characterization by several analytical methods, most notably inductively coupled plasma mass spectrometry and transmission electron microscopy reveal that metal ion deposition on the surface of these MOFs occurs in the form of nanoscale metal oxides, rather than yielding exchanged metal sites within the MOFs, as was previously reported. By contrast, these combined analytical methods do confirm that ligand-based PSE can occur in these MOFs. These findings provide new insight into the postsynthetic manipulation of MOF materials, highlight the importance of rigorously characterizing these materials to correctly assign their composition and structure, and provide a new route to making hybrid solids with a MOF@metal oxide architecture.

Tissue metabolomic profiling to reveal the therapeutic mechanism of reduning injection on LPS-induced acute lung injury rats.

Acute lung injury (ALI) is a severe respiratory disease. To date, no medical interventions have been proven effective in improving the outcome. Reduning injection (RDN) showed a potential effect in the therapy of ALI. However, seldom does research concern the holistic pharmacological mechanisms of RDN on ALI. A metabolomic strategy, based on two consecutive extractions of the lung tissue, has been developed to investigate therapeutic mechanisms of RDN on ALI model rat. The extraction procedure was an aqueous extraction with methanol–water followed by organic extraction with dichloromethane–methanol. According to the lipophilicity of extracts, aqueous extracts were analyzed on the T3 column and organic extracts on the C18 column. Partial least-squares discriminant analysis was utilized to identify differences in metabolic profiles of rats. A total of 14 potential biomarkers in lung tissue were identified, which mainly related to phospholipid metabolism, sphingolipid metabolism, nucleotide metabolism and energy metabolism. The combined analytical method provides complementary metabolomics information for exploring the action mechanism of RDN against ALI. And the obtained results indicate metabolomics is a promising tool for understanding the holism and synergism of traditional Chinese medicine.

Effect of far-field stresses and residual stresses incorporation in predicting fracture toughness of carbon nanotube reinforced yttria stabilized zirconia

Yttria-stabilized zirconia (YSZ) is a potential thermal insulating ceramic for high temperature applications (>1000 °C). YSZ reinforced with multi-walled carbon nanotubes (MWNTs) was processed via spark plasma sintering to produce dense, crack-free homogeneous sample and avoid any degradation of MWNTs when sintered using conventional routes. Despite porosity, the addition of MWNT has a profound effect in improving the damage tolerance of YSZ by allowing the retention of tetragonal phase. However, at some instances, the crack lengths in the MWNT reinforced YSZ matrices have been found to be longer than the standalone counterparts. Therefore, it becomes inappropriate to apply Anstis equation to calculate fracture toughness values. In this regard, a combined analytical cum numerical method is used to estimate the theoretical fracture toughness and quantitatively analyze the mechanics of matrix cracking in the reinforced composite matrices incorporating the effects of various factors (such as far-field stresses, volume fraction of MWNTs, change in the modulus and Poisson's ratio values along with the increase in porosity, and bridging and phase transformation mechanism) affecting the fracture toughness of YSZ-MWNT composites. The results suggest that the incorporation of far-field stresses cannot be ignored in estimating the theoretical fracture toughness of YSZ-MWNT composites.

Spin–orbit coupling and nonlinear modes of the polariton condensate in a harmonic trap

We consider a model of the exciton-polariton condensate based on a system of two Gross–Pitaevskii equations coupled by the second-order differential operator, which represents the spin–orbit coupling in the system. Also included are the linear gain, effective diffusion, nonlinear loss, and the standard harmonic-oscillator trapping potential, as well as the Zeeman splitting. By means of combined analytical and numerical methods, we identify stable two-dimensional modes supported by the nonlinear system. In the absence of the Zeeman splitting, these are mixed modes, which combine zero and nonzero vorticities in each of the two spinor components, and vortex–antivortex complexes. We have also found a range of parameters where the mixed-mode and vortex–antivortex states coexist and are stable. Sufficiently strong Zeeman splitting creates stable semi-vortex states, with vorticities 0 in one component and 2 in the other.

A new micromechanics approach for predicting the elastic response of polymer nanocomposites reinforced with randomly oriented and distributed wavy carbon nanotubes

A comprehensive investigation is carried out into the elastic behavior of carbon nanotube-reinforced polymer nanocomposites using two combined analytical micromechanical methods. A unit cell-based micromechanical method is developed to model the random distribution of carbon nanotubes within the polymer matrix. Also, the Eshelby method is used for modeling the random orientation state of carbon nanotubes within the matrix. Two fundamental aspects affecting the mechanical behavior of carbon nanotube/polymer nanocomposites, including the carbon nanotube waviness and the interphase formed due to the non-boned interaction between the carbon nanotube and the surrounding polymer, are considered in the unit cell method. Comparisons between the results of present method and experimental data reveal that for more realistic predictions, five important factors including, random orientation and random distribution of carbon nanotubes, interphase, waviness and transversely isotropic behavior of carbon nanotube should be considered in the modeling of carbon nanotube-reinforced polymer nanocomposites. The effects of volume fraction, number of waves and waviness factor of carbon nanotube as well as the type of random distribution of CNTs within the matrix on the elastic modulus of the polymer nanocomposites are studied.

Shear stress in a pressure-driven membrane system and its impact on membrane fouling from a hydrodynamic condition perspective: a review

Pressure-driven membrane technology has gained increasing popularity in municipal/domestic and industrial wastewater treatment, desalination, and water reclamation. Careful manipulation of surface shear stress, which plays a vital role in membrane fouling control from a purely hydrodynamic perspective, can minimise concentration polarisation of solute on flat sheet membranes, or enhance the particle back transport from hollow fibre membranes. This review considers the techniques to generate turbulence and shear at the membrane surface, the magnitude of shear stress, and the experimental, as well as numerical methods for evaluation of shear stress. The findings are presented in terms of the amount of shear stress reported to control membrane fouling in these systems. Operational disadvantages of fouling control via application of shear stress occur while changing the properties of the solute or particles, such as cell breakup, bacterial population change, or shear stress classification. The literature teaches that future developments on shear stress for membrane systems must be addressed, in addition to energy consumption, shear stress distribution and the development of combined analytical methods to characterise and visualise shear in situ for different membrane configurations. © 2016 Society of Chemical Industry

Vortex solitons in two-dimensional spin-orbit coupled Bose-Einstein condensates: Effects of the Rashba-Dresselhaus coupling and Zeeman splitting.

We present an analysis of two-dimensional (2D) matter-wave solitons, governed by the pseudospinor system of Gross-Pitaevskii equations with self- and cross attraction, which includes the spin-orbit coupling (SOC) in the general Rashba-Dresselhaus form, and, separately, the Rashba coupling and the Zeeman splitting. Families of semivortex (SV) and mixed-mode (MM) solitons are constructed, which exist and are stable in free space, as the SOC terms prevent the onset of the critical collapse and create the otherwise missing ground states in the form of the solitons. The Dresselhaus SOC produces a destructive effect on the vortex solitons, while the Zeeman term tends to convert the MM states into the SV ones, which eventually suffer delocalization. Existence domains and stability boundaries are identified for the soliton families. For physically relevant parameters of the SOC system, the number of atoms in the 2D solitons is limited by ∼1.5×10^{4}. The results are obtained by means of combined analytical and numerical methods.

Wiring up multiple layers of innovation ecosystems: Contemplations from Personal Health Systems Foresight

Many foresight exercises have been undertaken with the aim of improving the performance of innovation ecosystems. These ecosystems extend across different layers including the organisational, sectoral, regional, national and international dimensions. The interconnectedness of these layers has not have received much attention in foresight literature and practise. However, both the development and diffusion of innovations are subject to framework conditions not only within, but also across, multiple layers of innovation ecosystems.The design and management of foresight exercises are thus liable to addressing and serving these different layers — especially when the goal is to improve the performance and impact of such “interconnected and interdependent systems”. This paper develops further the concept of ‘multi-layered foresight’ by addressing multiple layers of innovation ecosystems in foresight design and management. We explore the implications of applying this type of foresight on improving systemic understanding, enhancing stakeholder networking and developing innovation capacities across the layers of ecosystems. The theoretical underpinnings are tested through a case study of the ‘Personal Health Systems (PHS) Foresight’ project. This project explored international future developments in the health sector, which is characterised by multiple disciplines, communities of practise, technologies, and geographical contexts. In the case of PHS the emerging innovation ecosystems are often conditioned by fragmented development communities, major barriers to market development, and duplication of efforts. The project combined analytical, social networking, online envisioning and scenario building methods to address complexity and create impact in multiple layers. Possible futures for personal health systems were explored through intense dialogues with stakeholders and a desirable future state was sketched through the success scenario methodology. The implications and strategic issues for different groups of stakeholders were outlined, enabling these stakeholders to articulate their efforts as part of a broader agenda at the multiple layers of innovation ecosystems.

Establishment of combined analytical method to extract the genes of interest from transcriptome data

Techniques for analyzing genome-wide expression profiles, such as the microarray technique and next-generation sequencers, have been developed. While these techniques can provide a lot of information about gene expression, selection of genes of interest is complicated because of excessive gene expression data. Thus, many researchers use statistical methods or fold change as screening tools for finding gene sets whose expression is altered between groups, which may result in the loss of important information. In the present study, we aimed to establish a combined method for selecting genes of interest with a small magnitude of alteration in gene expression by coupling with proteome analysis. We used hypercholesterolemic rats to examine the effects of a crude herbal drug on gene expression and proteome profiles. We could not select genes of interest by using standard methods. However, by coupling with proteome analysis, we found several effects of the crude herbal drug on gene expression. Our results suggest that this method would be useful in selecting gene sets with expressions that do not show a large magnitude of alteration.

Horizontal distributions of sprites derived from the JEM‐GLIMS nadir observations

AbstractGlobal Lightning and Sprite Measurements on Japanese Experiment Module (JEM‐GLIMS) started the nadir observations of lightning discharges and transient luminous events (TLEs) from the International Space Station (ISS) since November 2012. In the nadir observations, JEM‐GLIMS optical instruments have to simultaneously detect incomparably intense lightning emissions and weak TLE emissions. To distinguish TLEs, especially sprite events, from lightning events, combined data analytical methods are adopted: (1) a subtraction of the wideband camera image from the narrowband camera image, (2) a calculation of the intensity ratio between different photometer channels, and (3) an estimation of the polarization and charge moment changes for the TLE‐producing lightning discharges. We succeeded in identifying numbers of sprite events using the combined analytical methods, and here we report three sprite events detected by JEM‐GLIMS as a case study. In the subtracted images, sprite emissions are located over the area of the sprite‐producing lightning emissions. However, these sprites and sprite‐producing lightning discharges did not occur at the nadir point of the ISS. For this reason, the geometry conversion of the sprite and sprite‐producing lightning emissions as observed from the point just over the sprite‐producing lightning discharges is performed. In the geometry‐converted images, the locations of the sprite emissions are clearly displaced by 8–20 km from the peak positions of the sprite‐producing lightning emissions. Thus, the first quantitative spatial distributions of sprites and sprite‐producing lightning discharges from the JEM‐GLIMS nadir observations are revealed.

Rapid quantification method for Legionella pneumophila in surface water.

World-wide legionellosis outbreaks caused by evaporative cooling systems have shown that there is a need for rapid screening methods for Legionella pneumophila in water. Antibody-based methods for the quantification of L. pneumophila are rapid, non-laborious, and relatively cheap but not sensitive enough for establishment as a screening method for surface and drinking water. Therefore, preconcentration methods have to be applied in advance to reach the needed sensitivity. In a basic test, monolithic adsorption filtration (MAF) was used as primary preconcentration method that adsorbs L. pneumophila with high efficiency. Ten-liter water samples were concentrated in 10 min and further reduced to 1 mL by centrifugal ultrafiltration (CeUF). The quantification of L. pneumophila strains belonging to the monoclonal subtype Bellingham was performed via flow-based chemiluminescence sandwich microarray immunoassays (CL-SMIA) in 36 min. The whole analysis process takes 90 min. A polyclonal antibody (pAb) against L. pneumophila serogroup 1-12 and a monoclonal antibody (mAb) against L. pneumophila SG 1 strain Bellingham were immobilized on a microarray chip. Without preconcentration, the detection limit was 4.0 × 10(3) and 2.8 × 10(3) CFU/mL determined by pAb and mAb 10/6, respectively. For samples processed by MAF-CeUF prior to SMIA detection, the limit of detection (LOD) could be decreased to 8.7 CFU/mL and 0.39 CFU/mL, respectively. A recovery of 99.8 ± 15.9% was achieved for concentrations between 1-1000 CFU/mL. The established combined analytical method is sensitive for rapid screening of surface and drinking water to allow fast hygiene control of L. pneumophila.

Quantitative multimodal analyses of silver nanoparticle-cell interactions: Implications for cytotoxicity

This study demonstrates the value of combining complementary analytical methods to assess the surface binding and internalization of AgNPs differing in primary size (10–70nm) and surface (bPEI, PEG, citrate) in human T-lymphocytes, and to link this information with cytotoxicity of those AgNPs. Enhanced dark-field microscopy and imaging flow cytometry were used to semi-quantitatively assess cell–AgNP interactions while inductively coupled plasma mass spectrometry was used to quantitate those interactions. Extracellularly bound and intracellular AgNPs were distinguished by selective removal of cell surface bound NPs by chemical etching.By taking advantage of the combined analytical methods, we were able to quantify the cell surface bound and intracellular Ag NPs which indicated significantly higher extracellular binding and cellular uptake of cationic bPEI-AgNPs compared to citrate- and PEG-AgNPs. Although the toxicity (IC50) of AgNPs was size and surface coating dependent, the intracellular Ag concentration at each IC50 was similar, varying only from 35–62fg Ag/cell. This suggests that intracellularization is the main determinant of AgNPs toxicity in mammalian cells.While this study demonstrates the benefits of the multimodal analysis to reveal cellular interactions with AgNPs, the methodology has a potential to be used for other types of NPs and for further applications in nanotoxicology and nanomedicine.

Bioanalytical method validation for the simultaneous determination of ceftazidime and avibactam in rat plasma.

Combination therapies have gained momentum in the disease management strategies of various indications. While it is challenging and more time consuming to develop a combined analytical method, the strategy of simultaneous analysis offers significant advantages in terms of efficiency and cost-effectiveness. Due to a significant difference in efficacious dose for ceftazidime and avibactam, the calibration ranges validated in this paper were set to 0.05-50 μg/ml for ceftazidime and 0.005-5.0 μg/ml for avibactam. Interday results of ceftazidime were within 8% for accuracy and 9% for precision and within 9% for both accuracy and precision of avibactam. A sensitive and selective LC-MS/MS method was developed for the simultaneous quantification of ceftazidime and avibactam in rat plasma.