Autonomous Incident Detection on Spectrometers Using Deep Convolutional Models

This paper focuses on improving the performance of scientific instrumentation that uses glass spray chambers for sample introduction, such as spectrometers, which are widely used in analytical chemistry, by detecting incidents using deep convolutional models. The performance of these instruments can be affected by the quality of the introduction of the sample into the spray chamber. Among the indicators of poor quality sample introduction are two primary incidents: The formation of liquid beads on the surface of the spray chamber, and flooding at the bottom of the spray chamber. Detecting such events autonomously as they occur can assist with improving the overall operational accuracy and efficacy of the chemical analysis, and avoid severe incidents such as malfunction and instrument damage. In contrast to objects commonly seen in the real world, beading and flooding detection are more challenging since they are of significantly small size and transparent. Furthermore, the non-rigid property increases the difficulty of the detection of these incidents, as such that existing deep-learning-based object detection frameworks are prone to fail for this task. There is no former work that uses computer vision to detect these incidents in the chemistry industry. In this work, we propose two frameworks for the detection task of these two incidents, which not only leverage the modern deep learning architectures but also integrate with expert knowledge of the problems. Specifically, the proposed networks first localize the regions of interest where the incidents are most likely generated and then refine these incident outputs. The use of data augmentation and synthesis, and choice of negative sampling in training, allows for a large increase in accuracy while remaining a real-time system for inference. In the data collected from our laboratory, our method surpasses widely used object detection baselines and can correctly detect 95% of the beads and 98% of the flooding. At the same time, out method can process four frames per second and is able to be implemented in real time.

Determination of Background Concentrations of Ag, Pd, Pt and Au in Highly Mineralized Ground Waters at Sub-ng L–1 Concentrations by Online Matrix Separation/Pre-Concentration Coupled to ICP-SFMS

Though not regulated in directives such as the Water Framework Directive of the European Union, the investigation of geogenic background concentrations of certain elements such as precious metals is of increasing interest, in particular for the early detection of a potential environmental pollution due to the increased use in various industrial and technological applications and in medicine. However, the precise and accurate quantification of precious metals in natural waters is challenging due to the complex matrices and the ultra-low concentrations in the (sub-) ng L−1 range. A methodological approach, based on matrix separation and pre-concentration on the strong anion exchange resin TEVA® Resin in an online mode directly coupled to ICP-SFMS, has been developed for the determination of Ag, Pt, Pd and Au in ground water. Membrane desolvation sample introduction was used to reduce oxide-based spectral interferences, which complicate the quantification of these metals with high accuracy. To overcome errors arising from matrix effects—in particular, the highly varying major ion composition of the investigated ground water samples—an isotope dilution analysis and quantification based on standard additions, respectively, were performed. The method allowed to process four samples per hour in a fully automated mode. With a sample volume of only 8 mL, enrichment factors of 6–9 could be achieved, yielding detection limits <1 ng L−1. Validation of the trueness was performed based on the reference samples. This method has been used for the analysis of the total concentrations of Ag, Pt, Pd and Au in highly mineralized ground waters collected from springs located in important geological fault zones of Austria’s territory. Concentrations ranges of 0.21–64.2 ng L−1 for Ag, 0.65–6.26 ng L−1 for Pd, 0.07–1.55 ng L−1 for Pt and 0.26–1.95 ng L−1 for Au were found.

Determination of four naphthalenediols in cosmetic samples by sweeping-micellar electrokinetic chromatography and a comparison with HPLC

A sweeping micellar electrokinetic chromatography (sweeping-MEKC) method was developed for the determination of 1,7-naphthalenediol, 2,3-naphthalenediol, 1,5-naphthalenediol and 2,7-naphthalenediol in cosmetics. Several parameters affecting sweeping-MEKC method were studied systematically and the separation conditions were optimized as 20 mM NaH2PO4–110 mM SDS and 40% (v/v) MeOH (pH 2.4), with −22 kV applied voltage and UV detection at 230 nm. The sample matrix is 60 mmol L−1 NaH2PO4 and sample introduction was performed at 3 psi for 6 s. Separation of the four naphthalenediols was completed in less than 17 min. Limit of detection (LOD) and limit of quantitation (LOQ) are 0.0045∼0.0094 μg mL−1 and 0.015∼0.031 μg mL−1. Linear relationship (r 2 > 0.999) is satisfactory at the range of 0.1–10 μg mL−1. The developed method has been successfully applied to the determination of the four naphthalenediols in real cosmetic samples, with recoveries in foundation, sun cream and lotion in the range of 92.3%∼106.8% and relative standard deviation (RSD) less than 4.15%. A HPLC method described in the National Standards of the People’s Republic of China was carried out for the comparison with the proposed method. The results showed that the proposed sweeping-MEKC method has the advantages of fast, low cost with comparative sensitivity.

Isolation and Identification of Isocoumarin Derivatives With Specific Inhibitory Activity Against Wnt Pathway and Metabolome Characterization of Lasiodiplodia venezuelensis

The Wnt signaling pathway controls multiple events during embryonic development of multicellular animals and is carcinogenic when aberrantly activated in adults. Breast cancers are dependent on Wnt pathway overactivation mostly through dysregulation of pathway component protein expression, which necessitates the search for therapeutically relevant compounds targeting them. Highly diverse microorganisms as endophytes represent an underexplored field in the therapeutic natural products research. In the present work, the objective was to explore the chemical diversity and presence of selective Wnt inhibitors within a unique collection of fungi isolated as foliar endophytes from the long-lived tropical palm Astrocaryum sciophilum. The fungi were cultured, extracted with ethyl acetate, and screened for their effects on the Wnt pathway and cell proliferation. The endophytic strain Lasiodiplodia venezuelensis was prioritized for scaled-up fractionation based on its selective activity. Application of geometric transfer from analytical HPLC conditions to semi-preparative scale and use of dry load sample introduction enabled the isolation of 15 pure compounds in a single step. Among the molecules identified, five are original natural products described for the first time, and six are new to this species. An active fraction obtained by semi-preparative HPLC was re-purified by UHPLC-PDA using a 1.7 µm phenyl column. 75 injections of 8 µg were necessary to obtain sufficient amounts of each compound for structure elucidation and bioassays. Using this original approach, in addition to the two major compounds, a third minor compound identified as (R)-(-)-5-hydroxymellein (18) was obtained, which was found to be responsible for the significant Wnt inhibition activity recorded. Further studies of this compound and its structural analogs showed that only 18 acts in a highly specific manner, with no acute cytotoxicity. This compound is notably selective for upstream components of the Wnt pathway and is able to inhibit the proliferation of three triple negative breast cancer cell lines. In addition to the discovery of Wnt inhibitors of interest, this study contributes to better characterize the biosynthetic potential of L. venezuelensis.

Mode-Dependent Antiviral Activity of Medicinal Plant Extracts against the Mosquito-Borne Chikungunya Virus

The lack of specific treatment for chikungunya fever makes the need for anti-chikungunya virus agents more crucial. This study was conducted to evaluate 132 extracts obtained by sequential solvent extraction from 21 medicinal plants for cytopathic effect inhibitory activity using virus-infected Vero cells in two different sample introduction modes. Among the extracts, 42 extracts (31.8%) from 12 plants in the concurrent mode and three extracts (2.3%) from a plant in the non-concurrent mode displayed strong cytopathic effect inhibitory activity (cell viability ≥70%). Viral load quantification analysis unveiled that the extracts of Clinacanthus nutans (chloroform, ethyl acetate, and ethanol), Hydrocotyle sibthorpioides (ethanol), and Ocimum americanum (ethanol and methanol) hindered the release of viral progeny from the infected cells while the extracts of Ficus deltoidea (ethanol), Gynura bicolor (water), H. sibthorpioides (water), and O. americanum (chloroform and ethyl acetate) blocked the entry of virus into the cells. The extracts of Diodella sarmentosa (ethyl acetate), Diplazium esculentum (chloroform, ethyl acetate, and ethanol), and G. bicolor (ethanol) possessed virucidal effect and caused 5.41-log to 6.63-log reductions of viral load compared to the virus control. The results indicate that these medicinal plants are potential sources of anti-chikungunya virus agents that have varied modes of action.

Moving Toward a Handheld “Plasma” Spectrometer for Elemental Analysis, Putting the Power of the Atom (Ion) in the Palm of Your Hand

Many of the current innovations in instrument design have been focused on making them smaller, more rugged, and eventually field transportable. The ultimate application is obvious, carrying the instrument to the field for real time sample analysis without the need for a support laboratory. Real time data are priceless when screening either biological or environmental samples, as mitigation strategies can be initiated immediately upon the discovery that contaminant metals are present in a location they were not intended to be. Additionally, smaller “handheld” instruments generally require less sample for analysis, possibly increasing sensitivity, another advantage to instrument miniaturization. While many other instruments can be made smaller just by using available micro-technologies (e.g., eNose), shrinking an ICP-MS or AES to something someone might carry in a backpack or pocket is now closer to reality than in the past, and can be traced to its origins based on a component-by-component evaluation. While the optical and mass spectrometers continue to shrink in size, the ion/excitation source remains a challenge as a tradeoff exists between excitation capabilities and the power requirements for the plasma’s generation. Other supporting elements have only recently become small enough for transport. A systematic review of both where the plasma spectrometer started and the evolution of technologies currently available may provide the roadmap necessary to miniaturize the spectrometer. We identify criteria on a component-by-component basis that need to be addressed in designing a miniaturized device and recognize components (e.g., source) that probably require further optimization. For example, the excitation/ionization source must be energetic enough to take a metal from a solid state to its ionic state. Previously, a plasma required a radio frequency generator or high-power DC source, but excitation can now be accomplished with non-thermal (cold) plasma sources. Sample introduction, for solids, liquids, and gasses, presents challenges for all sources in a field instrument. Next, the interface between source and a mass detector usually requires pressure reduction techniques to get an ion from plasma to the spectrometer. Currently, plasma mass spectrometers are field ready but not necessarily handheld. Optical emission spectrometers are already capable of getting photons to the detector but could eventually be connected to your phone. Inert plasma gas generation is close to field ready if nitrogen generators can be miniaturized. Many of these components are already commercially available or at least have been reported in the literature. Comparisons to other “handheld” elemental analysis devices that employ XRF, LIBS, and electrochemical methods (and their limitations) demonstrate that a “cold” plasma-based spectrometer can be more than competitive. Migrating the cold plasma from an emission only source to a mass spectrometer source, would allow both analyte identification and potentially source apportionment through isotopic fingerprinting, and may be the last major hurdle to overcome. Finally, we offer a possible design to aid in making the cold plasma source more applicable to a field deployment.