Liquid marbles exhibit great potential for use as miniature labs for small‐scale laboratory operations, such as experiment and measurement. While important progress has been made recently in ...exploring their applications as microreactions, “on‐line” measurement of the components inside the liquid still remains a challenge. Herein, it is demonstrated that “on‐line” detection can be realized on magnetic liquid marbles by taking advantage of their unique magnetic opening feature. By partially opening the particle shell, electrochemical measurement is carried out with a miniaturized three‐electrode probe and the application of this technique for quantitative measurement of dopamine is demonstrated. Fully opened magnetic liquid marble makes it feasible to detect the optical absorbance of the liquid in a transmission mode. With this optical method, a glucose assay is demonstrated. Moreover, when magnetic particle shell contains low melting point material, e.g., wax, the liquid marble shows a unique encapsulation ability to form a rigid shell after heating, which facilitates the storage of the non‐volatile ingredients. These unique features, together with the versatile use as microreactors, enable magnetic liquid marbles to function as a miniature lab (or called “lab in a droplet”), which may find applications in clinical diagnostics, biotechnology, chemical synthesis, and analytical chemistry.
“On‐line” quantitative detection of liquid ingridents and biological assays is demonstratred in magnetic liquid marbles using electrochemical and optical approaches. The particle shell of magnetic liquid marbles can be hardened to preserve the samples/reagents when a low melting‐point material is present in the powder shell. These novel features, with the actuation and microreactor characteristics, make magnetic liquid marbles a promising candidate for “lab in a droplet”.
Introduction
At the start of the 2000s, the progressive diffusion of high-flux extracorporeal dialysis and membranes saw an increased use of high infusion volumes injected into the patient’s blood ...circuit following the advent of on-line water production plants.
Methodology
Our 15-year experience with on-line extracorporeal methodologies using very high infusion volumes has led to the detection of errors and weaknesses, thus allowing us to correct and provide for the implementation of appropriate technology in dialysis water production plants with the aim of ensuring a higher chemical-physical, bacteriological and endotoxin quality. The initial procedures had already been outlined in the 2005 Italian Guidelines, although still today Health Technicians and Nephrologists operating in the field are unable to take on board specific integrations for on-line methods due to a lack of upgrading of documentation in both European and non-European Guidelines.
Results
After more than 17 years’ experience, and in view of the technological implementations developed since 2005, we wish to put forward a series of suggestions in an attempt to improve the safety of on-line water, with uses ranging from drinking water, pre-treatment, osmosis, distribution circuit, hemodialysis monitors up to the most recent update of microbiological cultures.
Discussion
Additional, more stringent measures are required to prevent the occurrence of acute accidents during dialysis sessions and to reduce chronic inflammation-oxidation deriving from the use of not totally ultra-pure/sterile dialysis fluids.
Conclusion
Our point of view based on our long-standing experience, the proposals made relate to procedures to be applied in technological maintenance, which the consultant nephrologist and other relevant personnel such as microbiologists, biologists, and technical operators should adhere to rigorously to ensure that the production of dialysis water on-line is viewed on a par with a pharmacological administration.
The ability for nuclear magnetic resonance (NMR) spectroscopy to provide quantitative, structurally rich information makes this spectroscopic technique an attractive reaction monitoring tool. The ...practicality of NMR for this type of analysis has only increased in the recent years with the influx of commercially available benchtop NMR instruments and compatible flow systems. In this study, we aim to compare 19F NMR reaction profiles acquired under both on‐line continuous‐flow and stopped‐flow sampling methods, with modern benchtop NMR instrumentation, and two reaction systems: a homogeneous imination reaction and a biphasic activation of a carboxylic acid to acyl fluoride. Reaction trends with higher data density can be acquired with on‐line continuous‐flow analyses, and this work highlights that representative reaction trends can be acquired without any correction when monitoring resonances with a shorter spin–lattice relaxation time (T1), and with the used flow conditions. On‐line stopped‐flow analyses resulted in representative reaction trends in all cases, including the monitoring of resonances with a long T1, without the need of any correction factors. The benefit of easier data analysis, however, comes with the cost of time, as the fresh reaction solution must be flowed into the NMR system, halted, and time must be provided for spins to become polarized in the instrument's external magnetic field prior to spectral measurement. Results for one of the reactions were additionally compared with the use of a high‐field NMR.
This work presents a practical comparison of online stopped‐flow and continuous‐flow sampling methods for reaction monitoring using benchtop NMR. Two model reactions systems are monitored with each technique, and the results are directly compared. Benefits and key considerations between the two techniques are highlighted.
Aims
Amazon Mechanical Turk (MTurk) provides a crowdsourcing platform for the engagement of potential research participants with data collection instruments. This review (1) provides an introduction ...to the mechanics and validity of MTurk research; (2) gives examples of MTurk research; and (3) discusses current limitations and best practices in MTurk research.
Methods
We review four use cases of MTurk for research relevant to addictions: (1) the development of novel measures, (2) testing interventions, (3) the collection of longitudinal use data to determine the feasibility of longer‐term studies of substance use and (4) the completion of large batteries of assessments to characterize the relationships between measured constructs. We review concerns with the platform, ways of mitigating these and important information to include when presenting findings.
Results
MTurk has proved to be a useful source of data for behavioral science more broadly, with specific applications to addiction science. However, it is still not appropriate for all use cases, such as population‐level inference. To live up to the potential of highly transparent, reproducible science from MTurk, researchers should clearly report inclusion/exclusion criteria, data quality checks and reasons for excluding collected data, how and when data were collected and both targeted and actual participant compensation.
Conclusions
Although on‐line survey research is not a substitute for random sampling or clinical recruitment, the Mechanical Turk community of both participants and researchers has developed multiple tools to promote data quality, fairness and rigor. Overall, Mechanical Turk has provided a useful source of convenience samples despite its limitations and has demonstrated utility in the engagement of relevant groups for addiction science.
•Magnetic graphene was fabricated by a simple co-mixing method.•Magnetic graphene was used as adsorbent of modified QuEChERS.•A method for the determination of 26 OCPs residues in tobacco was ...established.•The proposed method has the advantages of simplicity, rapidity and high-efficiency.
In this study, magnetic graphene was used as modified quick, easy, cheap, effective, rugged and safe (QuEChERS) adsorbent for the determination of organochlorine pesticide (OCPs) residues in tobacco. To achieve the optimum conditions of modified QuEChERS procedure toward target analytes, several parameters affecting the clean-up efficiency including the amount of the adsorbent and clean-up time were investigated. Under the optimized conditions, a method for the determination of 26 OCPs residues in tobacco was established by coupling the modified QuEChERS procedure to on-line gel permeation chromatography–gas chromatography–tandem mass spectrometry (on-line GPC–GC–MS2). The limits of detection of proposed method for 26 OCPs residues ranged from 0.01275 to 3.150ng/g. And good linearities of the proposed method were obtained with coefficients of determination (R2) greater than 0.9985 for all target analytes. Good reproducibility of method was obtained as intra- and inter-day precisions, the relative standard deviations were less than 11.1 and 15.0%, respectively. The apparent recoveries were in the range of 64–126% at different concentrations for real samples. Compared with the reported methods for the determination of OCPs residues in tobacco, the proposed method has the advantages of simple to operate, low cost and high clean-up ability. Finally, the method was successfully applied to the analysis of OCPs residues in real samples.
•Magnetic particles in solid phase extraction for metal determination.•Synthesis, characterization, classification and applications of MPs.•On-line implementation in SIA, LOV and microfluidic ...systems.•Critical evaluation of on-line column packing in MSPE.
The use of magnetic materials in solid phase extraction has received considerable attention in recent years taking into account many advantages arising from the inherent characteristics of magnetic particles. Magnetic solid phase extraction (MSPE) methodology overcomes problems such as column packing and phase separation, which can be easily performed by applying an external magnetic field. The use of magnetic particles in automatic systems is growing over the last few years making the on-line operation of MSPE a promising technique in the frame of green chemistry. This article aims to provide all recent progress in the research of novel magnetic materials as sorbents for metal preconcentration and determination coupled with different detection systems as well as their implementation in sequential injection and microfluidic systems. In addition, a description of preparation, characterization as well as applications of various types of magnetic materials, either with organic or inorganic coating of the magnetic core, is presented. Concluding remarks and future trends are also commented.
Knowledge of molecular weight, oligomeric states, and quaternary arrangements of proteins in solution is fundamental for understanding their molecular functions and activities. We describe here a ...program SAXSMoW 2.0 for robust and quick determination of molecular weight and oligomeric state of proteins in dilute solution, starting from a single experimental small‐angle scattering intensity curve, I(q), measured on a relative scale. The first version of this calculator has been widely used during the last decade and applied to analyze experimental SAXS data of many proteins and protein complexes. SAXSMoW 2.0 exhibits new features which allow for the direct input of experimental intensity curves and also automatic modes for quick determinations of the radius of gyration, volume, and molecular weight. The new program was extensively tested by applying it to many experimental SAXS curves downloaded from the open databases, corresponding to proteins with different shapes and molecular weights ranging from ~10 kDa up to about ~500 kDa and different shapes from globular to elongated. These tests reveal that the use of SAXSMoW 2.0 allows for determinations of molecular weights of proteins in dilute solution with a median discrepancy of about 12% for globular proteins. In case of elongated molecules, discrepancy value can be significantly higher. Our tests show discrepancies of approximately 21% for the proteins with molecular shape aspect ratios up to 18.
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