Bulk Extraction Research Articles

Study of the leaching and pore evolution in large particles of a sulfide ore

A long-term leach investigation was undertaken on particles of a sulfide ore to determine the nature of solution transport into large particles and to identify the primary roles concentrations of acid and oxidant on controlling solution transport. Bulk leaching results showed that in the case of Fe leaching, both [Fe3+] and [H2SO4] promoted the extent of Fe extraction whereas the extent of Zn and Pb extraction was dependent only on [H2SO4]. Based on the bulk extraction of Al and Mg, it appears that [H2SO4] drives the expansion of inner particle pores by promoting the dissolution of gangue minerals. The findings indicated that the generation of cracks and/or pores to enhance solution contact with the value minerals remains the critical factor in improving value metal recovery from this type of material during heap leaching. Comparative laboratory and synchrotron X-CT studies were also undertaken on single ore particles using a novel in–situ leach cup technique. Similar to the solution results, the acid concentration was shown to be critical in creating effective porosity and pore networks through the centre of the particles for the transport of solution to value minerals and subsequent leaching and transport to the bulk solution. This occurred primarily through the dissolution of auxiliary aluminosilicate gangue minerals, which in turn created networks of porosity for effective bulk solution transport into large particles during heap leaching. This, in turn, enables local solution micro-environments where leaching occurs at the solid-liquid interface. Following the accessibility of bulk solution into the particle, the reaction is then governed by surface-mineral reactions between the sulfidic minerals.

Evolution of Environmentally Friendly Strategies for Metal Extraction

The demand for the recovery of valuable metals and the need to understand the impact of heavy metals in the environment on human and aquatic life has led to the development of new methods for the extraction, recovery, and analysis of metal ions. With special emphasis on environmentally friendly approaches, efforts have been made to consider strategies that minimize the use of organic solvents, apply micromethodology, limit waste, reduce costs, are safe, and utilize benign or reusable materials. This review discusses recent developments in liquid- and solid-phase extraction techniques. Liquid-based methods include advances in the application of aqueous two- and three-phase systems, liquid membranes, and cloud point extraction. Recent progress in exploiting new sorbent materials for solid-phase extraction (SPE), solid-phase microextraction (SPME), and bulk extractions will also be discussed.

Hypoglycemic, Antitussive and Analgesic Effects of Nanoparticles of Cordia myxa Fruits Extract

Background: Cordia myxa is a plant from Boraginaceae family and has many useful therapeutic properties. Aim of the study is to compare the pharmacological efficacy of Cordia myxa hydro-alcoholic extract (Bulk Extract [BE]) and nanoparticles of hydro-alcoholic extract (NPE) including hypoglycemic, antitussive, anti-inflammatory and analgesic activity. Methods: Hydro-alcoholic maceration extract of dry fruits was powdered to nanoparticle size by ball-milling technique. Hyperglycemia and cough were induced in mice by alloxan (120 mg/kg, i.p.) and ammonia, respectively. Inflammatory and analgesic evaluations of extracts were carried out with the formalin-induced edema in the mice paw and acetic acid tests. NPE and BE were administrated at single dose (750 mg/kg, i.p.). Positive control group was received dextromethorphan (10 mg/kg, orally) in cough and indomethacin (25 mg/kg, orally) for analgesic models. Blood glucose level, the number of coughs and writhes and duration of foot lickings were calculated. Results: The blood glucose did not statistically reduce by extracts. Both extracts could significantly inhibit the frequency of cough and dramatically reduce the duration of paw licking. NPE could significantly reduce writhes. Conclusion: We concluded that extracts had no hypoglycemic activity. Both extracts created therapeutic activities better than dextromethorphan. NPE exerted better anti-inflammatory and analgesic activity compared to BE.

Defense response of seedling plumule and mesocotyl of sorghum to infection by Sporisorium sorghi, causing covered kernel smut in relation to disease resistance classes

Susceptibility of sorghum seedlings to infection by Sporisorium sorghi, the fungus causing covered kernel smut (CKS) disease, is limited to the period between the sowing of the seed and emergence of the seedling. Microscopy and PCR diagnosis of 7-day-old infected seedlings detected hyphae of S. sorghi in plumule and mesocotyl tissue but not in coleoptile and radicle tissue. Percent infected seedling plumule and mesocotyl tissue detected by microscopy and PCR corresponded well to field resistance classes for CKS in mature panicles of both sorghums tested with Giza-15 being highly susceptible and hybrid Shandweel-305 being resistant. Bulk extracts of phenolics and antioxidants from seedling plumule and mesocotyl tissues of hybrid Shandweel-305 cv significantly inhibited the in vitro mycelial growth of S. sorghi more than those from Giza-15 cv. Moreover, bulk extracts of plumule and mesocotyl tissue of seedlings grown from seed inoculated with S. sorghi teliospores contained higher phenolic and antioxidant content in the resistant hybrid (Shandweel-305) than the highly susceptible cultivar (Giza-15). Similarly, bulk extracts of plumule and mesocotyl tissue of 7-day-old seedlings grown from seed inoculated with S. sorghi teliospores contained higher phenolic and antioxidant content in the resistant hybrid (Shandweel-305) than the highly susceptible cultivar (Giza-15). Ferulic, isorhamnetin and kaempferol acids were detected only in plumule and mesocotyl tissue of resistant hybrid Shandweel-305, whereas ellagic, fumaric and vanillic acids were detected only in highly susceptible Giza-15 cv. Ferulic acid added to malt dextrose broth medium significantly inhibited in vitro teliospore germination and mycelial growth of S. sorghi, especially when added at the highest concentrations. This research established that the mode of seedling infection of sorghum by S. sorghi is almost exclusively through the plumule and mesocotyl tissue. Within these tissues, the presence of the pathogen can induce host production of phenolics, including the fungitoxic ferulic acid and antioxidants at higher concentrations within the resistant sorghum than in the highly susceptible cultivar.

Establishing arthropod community composition using metabarcoding: Surprising inconsistencies between soil samples and preservative ethanol and homogenate from Malaise trap catches.

DNA metabarcoding allows the analysis of insect communities faster and more efficiently than ever before. However, metabarcoding can be conducted through several approaches, and the consistency of results across methods has rarely been studied. We compare the results obtained by DNA metabarcoding of the same communities using two different markers – COI and 16S – and three different sampling methods: (a) homogenized Malaise trap samples (homogenate), (b) preservative ethanol from the same samples, and (c) soil samples. Our results indicate that COI and 16S offer partly complementary information on Malaise trap samples, with each marker detecting a significant number of species not detected by the other. Different sampling methods offer highly divergent estimates of community composition. The community recovered from preservative ethanol of Malaise trap samples is significantly different from that recovered from homogenate. Small and weakly sclerotized insects tend to be overrepresented in ethanol while strong and large taxa are overrepresented in homogenate. For soil samples, highly degenerate COI primers pick up large amounts of nontarget DNA and only 16S provides adequate analyses of insect diversity. However, even with 16S, very little overlap in molecular operational taxonomic unit (MOTU) content was found between the trap and the soil samples. Our results demonstrate that none of the tested sampling approaches is satisfactory on its own. For instance, DNA extraction from preservative ethanol is not a valid replacement for destructive bulk extraction but a complement. In future metabarcoding studies, both should ideally be used together to achieve comprehensive representation of the target community.

The bioactivities of the neem (seeds and leaves) against Callosobruchus maculatus on a Vigna Subterranean L.

This research reports the novel bioactivities of neem leaves powder, neem leaves concentrate, neem seeds powder and neem seeds oil against the weevil (Callosobruchus maculatus) on bambara groundnut. The leaves were grounded, crushed and subjected to ethanol to get the concentrate. While the seeds were dried under shade for one week, ground into fine particles. Cold bulk extraction was then used to obtain the neem seeds oil. The mortality count of Callosobruchus maculatus (C. maculatus) was studied by exposing the weevil to neem treated bambara groundnut at different days under laboratory condition. The neem dosage were 0.0, 0.1, 0.5 1.0 g/10 g of bambara groundnut. The percentage weight loss and seed damage were also determined at the end. The results indicated that neem seeds oil and neem leaves concentrate provided effective and comparable mortality counts against the C. maculatus. Again the neem powder (seeds and leaves) mortality counts were also comparable, but were less effective against the weevils as compared to the neem oil and concentrate at least for the first two days. Therefore, these neem materials could be used as biopesticides at the dose of _0.1 per 10 g to prevent C. maculatus attack on bambara groundnut during storage. This will reduce the usage of synthetic pesticides, thereby preventing their adverse residual effects on human and the environment.

Seismic inversion for fluid bulk modulus based on elastic impedance

Beginning with the simplification of Gassmann's fluid substitution equation, we propose a simplified bulk modulus of saturated rock in terms of fluid bulk modulus and porosity. Using relationship between reflection coefficients and scattering function, we derive a linearized PP-wave reflection coefficient as a function of fluid bulk modulus and modified porosity, and we also present the corresponding elastic impedance, which is useful for modeling how fluids affect seismic reflection amplitudes. The accuracy of derived reflection coefficient is confirmed in the case of maximum incidence angle being around 30°. Using the derived reflection coefficient and EI, we establish an inversion approach to estimate fluid bulk modulus and porosity from observed seismic data, which involves 1) the estimation of EI from partially stack seismic data, and 2) the extraction of fluid bulk modulus from estimated EI datasets. The extraction of fluid bulk modulus is implemented using a nonlinear inversion approach. Using the derived elastic impedance we compute the gradient of energy residual with respect to model vector directly, which allows us to implement the nonlinear inversion stably. Synthetic tests confirm the stability and robustness of the proposed inversion approach, and applying the inversion approach to a real dataset we obtain meaning results of fluid bulk modulus that are valuable for fluid identification in reservoirs.

A DNA barcode library for 5,200 German flies and midges (Insecta: Diptera) and its implications for metabarcoding-based biomonitoring.

This study summarizes results of a DNA barcoding campaign on German Diptera, involving analysis of 45,040 specimens. The resultant DNA barcode library includes records for 2,453 named species comprising a total of 5,200 barcode index numbers (BINs), including 2,700 COI haplotype clusters without species‐level assignment, so called “dark taxa.” Overall, 88 out of 117 families (75%) recorded from Germany were covered, representing more than 50% of the 9,544 known species of German Diptera. Until now, most of these families, especially the most diverse, have been taxonomically inaccessible. By contrast, within a few years this study provided an intermediate taxonomic system for half of the German Dipteran fauna, which will provide a useful foundation for subsequent detailed, integrative taxonomic studies. Using DNA extracts derived from bulk collections made by Malaise traps, we further demonstrate that species delineation using BINs and operational taxonomic units (OTUs) constitutes an effective method for biodiversity studies using DNA metabarcoding. As the reference libraries continue to grow, and gaps in the species catalogue are filled, BIN lists assembled by metabarcoding will provide greater taxonomic resolution. The present study has three main goals: (a) to provide a DNA barcode library for 5,200 BINs of Diptera; (b) to demonstrate, based on the example of bulk extractions from a Malaise trap experiment, that DNA barcode clusters, labelled with globally unique identifiers (such as OTUs and/or BINs), provide a pragmatic, accurate solution to the “taxonomic impediment”; and (c) to demonstrate that interim names based on BINs and OTUs obtained through metabarcoding provide an effective method for studies on species‐rich groups that are usually neglected in biodiversity research projects because of their unresolved taxonomy.

Studies on the radiolytic degradation of N,N-dioctyl-2-hydroxyacetamide using dynamic light scattering and ATR-FTIR spectroscopy

Abstract The bulk extraction of Nd(III) from 4 M nitric acid medium was studied in a solution of N,N-di-octyl-2-hydroxyacetamide (DOHyA) in n-dodecane as a function of γ absorbed dose up to 750 kGy. The average size of reverse micellar aggregates in the irradiated and un-irradiated DOHyA samples after the extraction of Nd(III) was measured by dynamic light scattering (DLS) spectroscopy. The effect of absorbed dose of γ radiation and concentration of Nd(III) in the organic phase on the aggregation behavior of DOHyA was investigated by DLS measurements and ATR-FTIR spectroscopy. The data on irradiated and un-irradiated samples were compared. FT-IR analysis of the irradiated samples of DOHyA showed the formation of degradation products which were mainly identified as hydroxyacetic acid and primary or secondary amines.

Direct screening of food packaging materials for post-polymerization residues, degradation products and additives by liquid extraction surface analysis nanoelectrospray mass spectrometry (LESA-nESI-MS)

Materials in direct contact with food should be monitored for the presence of species able to migrate into food. A direct method based on liquid extraction surface analysis nanoelectrospray mass spectrometry (LESA-nanoESI-MS) was developed for the analysis of the migrating species from a polymer film. Different types of molecules: post-polymerization residues, degradation products (oligomers resulting from polymer recycling, products of polymer oxidative degradation) and anti-oxidant additives (vitamin E) were demonstrated to be detected and identified, and determined quantitatively if relevant calibration standards are available. The method was validated by a comparison a standard method based on with bulk extraction mass spectrometry. It offers considerable advantages over the latter in terms of drastically reduced analysis time and solvent consumption. Also, LESA-nanoESI-MS produced simpler spectra (limited to compounds able to migrate into food) than Direct Analysis in Real Time (DART).

Light-inducible activation of cell cycle progression in Xenopus egg extracts under microfluidic confinement.

Cell-free Xenopus egg extract is a widely used and biochemically tractable model system that allows recapitulation and elucidation of fundamental cellular processes. Recently, the introduction of microfluidic extract manipulation has enabled compartmentalization of bulk extract and a newfound ability to study organelles on length scales that recapitulate key features of cellular morphology. While the microfluidic confinement of extracts has produced a compelling platform for the in vitro study of cell processes at physiologically-relevant length scales, it also imposes experimental limitations by restricting dynamic control over extract properties. Here, we introduce photodegradable polyethylene glycol (PEG) hydrogels as a vehicle to passively and selectively manipulate extract composition through the release of proteins encapsulated within the hydrogel matrix. Photopatterned PEG hydrogels, passive to both extract and encapsulated proteins, serve as protein depots within microfluidic channels, which are subsequently flooded with extract. Illumination by ultraviolet light (UV) degrades the hydrogel structures and releases encapsulated protein. We show that an engineered fluorescent protein with a nuclear localization signal (GST-GFP-NLS) retains its ability to localize within nearby nuclei following UV-induced release from hydrogel structures. When diffusion is considered, the kinetics of nuclear accumulation are similar to those in experiments utilizing conventional, bulk fluid handling. Similarly, the release of recombinant cyclin B Δ90, a mutant form of the master cell cycle regulator cyclin B which lacks the canonical destruction box, was able to induce the expected cell cycle transition from interphase to mitosis. This transition was confirmed by the observation of nuclear envelope breakdown (NEBD), a phenomenological hallmark of mitosis, and the induction of mitosis-specific biochemical markers. This approach to extract manipulation presents a versatile and customizable route to regulating the spatial and temporal dynamics of cellular events in microfluidically confined cell-free extracts.

Accessibility and mobility of hydrocarbons in lacustrine shale: Solvent flow-through extraction experiments on Eocene oil shales from Bohai Bay Basin, eastern China

In order to examine the mobility of hydrocarbons in a lacustrine shale oil system, three cylindrical core plugs from the Eocene Shahejie Formation lacustrine shale oil system in the Jiyang Depression were sequentially extracted with dichloromethane (DCM) in flow-through experiments under controlled stress conditions in a tri-axial flow cell. Orientations of the three sample plugs were perpendicular to bedding (#1) and parallel to bedding (#2 and #3). Post-experiment Micro-CT analysis confirmed three different flow patterns: Cross bedding flow (#1), minor bedding-parallel flow (#2), and extensive bedding-parallel flow along open fractures (#3). Extraction times were 28 days, 7 days and 3 days, for samples #1, #2 and #3, respectively. Sequential series of extracts from the samples were analyzed using gas chromatography. For comparison, hydrocarbon compositions were also determined on bulk extracts of powdered original sister-sample material and the residues after flow-through experiments.The mobilities of hydrocarbons are controlled by the flow direction and fracture intensity and orientations. For sample #1, DCM flow-through extraction yielded mostly hydrocarbons associated with matrix kerogen. This flow-extracted bitumen was found to be much heavier than that extracted from the other two samples, and to have a lower mobility. The hydrocarbons extracted from the sample #2 were the lightest. For sample #3, containing micro-fractures along the bedding planes, the extraction process was apparently very effective, not only dissolving HC from the fractures but also some HC from the kerogen.The characteristic hydrocarbon compositions of the samples were essentially retained in all extracts, although lighter hydrocarbons (<C19) were extracted somewhat preferentially. After the flow-through experiments the Rock-Eval S1 values had decreased by 81%, 56% and 84%, respectively, for all three samples, indicating that the hydrocarbons were extracted to different extents during the flow-through tests. Additionally, the Rock-Eval S2 values decreased by 29%, 0.4%, and 16%, for the three samples, respectively, showing that the flow-through tests on two of the samples also extracted significant amounts of organic material commonly interpreted as “heavy-hydrocarbons”. The free hydrocarbons in micro-fractures, especially fractures along the bedding, could be very important for shale oil mobilization and the intervals with well-developed laminae provide horizontal fracturing intervals that are most favorable.

Reconstitution of Cell-cycle Oscillations in Microemulsions of Cell-free Xenopus Egg Extracts.

Real-time measurement of oscillations at the single-cell level is important to uncover the mechanisms of biological clocks. Although bulk extracts prepared from Xenopus laevis eggs have been powerful in dissecting biochemical networks underlying the cell-cycle progression, their ensemble average measurement typically leads to a damped oscillation, despite each individual oscillator being sustained. This is due to the difficulty of perfect synchronization among individual oscillators in noisy biological systems. To retrieve the single-cell dynamics of the oscillator, we developed a droplet-based artificial cell system that can reconstitute mitotic cycles in cell-like compartments encapsulating cycling cytoplasmic extracts of Xenopus laevis eggs. These simple cytoplasmic-only cells exhibit sustained oscillations for over 30 cycles. To build more complicated cells with nuclei, we added demembranated sperm chromatin to trigger nuclei self-assembly in the system. We observed a periodic progression of chromosome condensation/decondensation and nuclei envelop breakdown/reformation, like in real cells. This indicates that the mitotic oscillator functions faithfully to drive multiple downstream mitotic events. We simultaneously tracked the dynamics of the mitotic oscillator and downstream processes in individual droplets using multi-channel time-lapse fluorescence microscopy. The artificial cell-cycle system provides a high-throughput framework for quantitative manipulation and analysis of mitotic oscillations with single-cell resolution, which likely provides important insights into the regulatory machinery and functions of the clock.

Geochemistry of Al and Fe in freshwater and coastal water colloids from the west coast of Southern Africa

Suspended iron-rich colloids play an important role in nutrient and contaminant transport in fluvial systems, and may ultimately provide an important source of Fe which is required for marine biological productivity. Despite being fundamental to Fe colloid behaviour in biogeochemical systems, the physical and chemical characteristics of these colloids are poorly constrained, especially at the molecular level. Here we combine traditional chemical extraction techniques with X-ray Absorption Near-edge Structure (XANES) spectroscopy to investigate and compare the bulk and molecular-level speciation of Fe and Al in suspended colloids from fluvial (Berg, Olifants and Orange Rivers) and marine sampling sites on the western margin of Southern Africa. The bulk extraction methodology shows a variable distribution of Fe among five different operationally-defined Fe pools, yet our spectroscopy results reveal that the majority of particles in the 10 nm–4 µm size fraction do not match crystalline or residual Fe spectral signatures and are thus likely to be poorly-crystalline. Aluminium K-edge XANES reveals that the Al coordination environment in aquatic colloids is diverse (e.g., relative to oxo ligands, the number of coordinated OH− ligands ranges between 0 and 6), and that the smallest sized colloids are always highly hydroxylated (i.e., their coordination environment is similar to Al in Al(OH)3 or 1:1 clays). The Al XANES further reveals a common association between Al and Fe-rich colloids, where the average measured Al/Fe ratio is 0.10 (±0.09) among all the particles measured in this study. The Al that co-occurs with Fe preferentially has a coordination environment similar to Al in 1:1 clays (i.e., two oxo ligands and four hydroxyl ligands), either further implying the amorphous nature of the Fe colloids or reflecting Al as surface complexes or as inclusions of nano-sized Al clusters. The observed high degree of disorder and the presence of Al association/substitution in iron-rich colloids observed in the Southern African systems will strongly influence the biogeochemical behaviour of these colloids (e.g., surface sorption capacity, solubility and dissolution rates). These findings contribute greatly to our understanding of natural Fe colloid and nanoparticle speciation and are anticipated to have global relevance to other aquatic systems in which ‘reactive’ or ‘poorly crystalline’ classes of suspended particulate Fe have been identified.

Application of Mg(OH)2 Nanosheets for Conservation and Restoration of Precious Documents and Cultural Archives

Magnesium hydroxide (Mg(OH)2) nanosheets were explored as an effective material for the restoration and conservation of paper-based cultural archives and compared with the commonly used Ca(OH)2 nanoparticles. The (Mg(OH)2) nanosheets were applied to filter paper as a reference, as well as to new and old paper samples. The effectiveness of Mg(OH)2 nanosheets was evaluated by (i) a pH test of the surface and the bulk extracts, (ii) measuring the alkaline reserve and correlating it with the enhancement in life expectancy, and (iii) in terms of mechanical strength. The alkaline reserve test indicated an increase in the alkaline buffer, which resulted in markedly reduced acidic content of the samples. It was inferred from the improved properties that Mg(OH)2 nanosheets coated the paper as a lamination sheet and protected it as the first line of defense against acidic environmental attack. Moreover, its presence within the paper acted as an alkaline reserve and also as reinforcement in the form of an inorganic nanosheet. The results suggest that the nanosheets are an innovative, compatible, and efficient material for the consolidation and restoration of old and new paper samples.

In vitro activity of a combination of bacteriophages and antimicrobial plant extracts.

The continuing threat of antimicrobial resistance presents a considerable challenge to researchers to develop novel strategies ensuring that bacterial infections remain treatable. Many plant extracts have been shown to have antibacterial properties and could potentially be combined with other antibacterial agents to create more effective formulations. In this study, the antibacterial activity of three plant extracts and virulent bacteriophages have been assessed as individual components and in combination. When assessed with a modified suspension test, these plant extracts also exhibit antiviral activity at bacterial inhibitory concentrations. Hence, to investigate any potential additive effects between the extracts and virulent phages, the extracts were tested at subantiviral concentrations. Phages alone and in combination with plant extracts significantly reduced (P<0·05) the bacterial concentration compared to untreated and extract treated controls up to 6h (2-3log10 ), but this reduction did not extend to 24h. In most cases, the phage and extract combinations did not significantly reduce bacterial content compared to phages alone. Additionally, there was little impact on the ability of the phages to reproduce within their bacterial hosts. To our knowledge, this study represents the first of its kind, in which antimicrobial plant extracts have been combined with virulent phages and has highlighted the necessity for plant extracts to be functionally characterized prior to the design of combinatorial therapies. Significance and Impact of Study This preliminary study provides insights into the potential combination of bacteriophages and antimicrobial plant bulk extracts to target bacterial pathogens. It is to our knowledge the first time in which virulent bacteriophages have been combined with antimicrobial plant extracts.

The fate of arsenic in groundwater discharged to the Meghna River, Bangladesh

Environmental contextArsenic contamination of groundwater is a major environmental problem in many areas of the world. In south-east Asia, iron-rich reducing groundwater mixes with oxidising river water in hyporheic zones, precipitating iron oxides. These oxides can act as a natural reactive barrier capable of accumulating elevated solid-phase concentrations of arsenic. AbstractShallow, anoxic aquifers within the Ganges–Brahmaputra–Meghna Delta (GBMD) commonly contain elevated concentrations of arsenic (As), iron (Fe) and manganese (Mn). Highly enriched solid-phase concentrations of these elements have been observed within sediments lining the banks of the Meghna River. This zone has been described as a Natural Reactive Barrier (NRB). The impact of hydrological processes on NRB formation, such as transient river levels, which drive mixing between rivers and aquifers, is poorly understood. We evaluated the impact of groundwater flow dynamics on hydrobiogeochemical processes that led to the formation of an Fe- and Mn-rich NRB containing enriched As, within a riverbank aquifer along the Meghna River. The NRB dimensions were mapped using four complementary elemental analysis methods on sediment cores: X-ray fluorescence (XRF), aqua regia bulk extraction, and HCl and sodium phosphate leaching. It extended from 1.2 to 2.4 m in depth up to 15 m from the river’s edge. The accumulated As was advected to the NRB from offsite and released locally in response to mixing with aged river water. Nearly all of the As was subsequently deposited within the NRB before discharging to the Meghna. Significant FeII release to the aqueous phase was observed within the NRB. This indicates the NRB is a dynamic zone defined by the interplay between oxidative and reductive processes, causing the NRB to grow and recede in response to rapid and seasonal hydrologic processes. This implies that natural and artificially induced changes in river stages and groundwater-tables will impact where As accumulates and is released to aquifers.

Direct detection of surface localized specialized metabolites from Glycyrrhiza lepidota (American licorice) by leaf spray mass spectrometry

Leaf spray-MS minimizes tissue manipulation by effectively and quickly assessing in vivo specialized metabolites from intact plant tissue surfaces, including trichome metabolites. Intact leaves of Glycyrrhiza lepidota Pursh. (American licorice) were analyzed by direct electrospray leaf spray-MS, an ambient ionization technique. Comparison of metabolites detected by leaf spray-MS to those from LC-MS of bulk tissue and trichome enriched extracts showed dramatic differences. Leaf spray-MS results suggest that in specific situations this approach could complement traditional LC-MS analysis of bulk extracts. Leaf spray-MS as a metabolomics technique eliminates sample pretreatment and preparation allowing for rapid sampling in real time of living intact tissues. Specialized metabolites on the surface of tissues such as glandular trichomes metabolites are detected by leaf spray-MS.

Comparative study of bulk and partial digestion methods for airborne PM10-bound elements in a high mineral dust urban site in Constantine, Algeria

ABSTRACTWhen high mineral loads in atmospheric particulate matter (PM) are present, particular attention should be paid to the selection of appropriate acidic digestion protocols for wet chemical analysis. We report on a comparative study of elemental recovery yields from five different pre-analytical acid digestion procedures for mineral-rich urban background PM10 samples collected in the city of Constantine (Northeastern Algeria). Five reference materials (NIST 1633b, UPM 1648, NAT-7, SO-2 and SO-4) were also digested according to the same protocols. The selected acidic digestion/extraction procedures are widely used for PM chemical analysis and comprise P1 (HNO3/HF/HCl), P2 (HCl/HNO3), P3 (HCl/H2O2/HNO3), P4 (HNO3/HF/HClO4) and P5 (HNO3/H2O2); the latter assisted with microwave digestion. Elemental recovery yields were compared for major and trace elements typically determined in PM for source apportionment analysis and the results evidenced large differences. For most elements, the bulk extraction procedures (requiring the use of HF) allowed a full elemental recovery, particularly for elements that are associated with aluminium silicate species and oxides that are resistant to mild acid attack. In contrast, in the extraction protocols without HF low recovery yields were obtained for elements such as Al, Ti, Zr, Sc and other aluminium silicate-related elements in PM10 samples with high mineral dust load. We highlight that the European standard digestion method EN-14902:2005 should be applied specifically for the metals for which this method was developed, but caution should be taken when the analysis of other elements in PM is required, especially in urban areas where road and vehicle wear dust is likely to be a major component of ambient PM. When using wet chemistry analysis for PM source apportionment studies, we strongly recommend HF bulk dissolution of samples to ensure the reliability of the geochemical information when coupled with an appropriate analytical tool.

A droplet digital PCR (ddPCR) assay to detect Helicoverpa armigera (Lepidoptera: Noctuidae) in bulk trap samples.

Moths in the genus Helicoverpa are some of the most important agricultural pests in the world. Two species, H. armigera (Hübner) and H. zea (Boddie), cause the majority of damage to crops and millions of dollars are spent annually on control of these pests. The recent introduction of H. armigera into the New World has prompted extensive survey efforts for this species in the United States. Surveys are conducted using bucket traps baited with H. armigera pheromone, and, because the same pheromone compounds attract both species, these traps often capture large numbers of the native H. zea. Adult H. armigera and H. zea are very similar and can only be separated morphologically by minor differences in the genitalia. Thus, a time consuming genitalic dissection by a trained specialist is necessary to reliably identify either species, and every specimen must be dissected. Several molecular methods are available for differentiating and identifying H. armigera and H. zea, including two recently developed rapid protocols using real-time PCR. However, none of the published methods are capable of screening specimens in large batches. Here we detail a droplet digital PCR (ddPCR) assay that is capable of detecting a single H. armigera in a background of up to 999 H. zea. The assay has been tested using bulk extractions of 1,000 legs from actual trap samples and is effective even when using poor quality samples. This study provides an efficient, rapid, reproducible, and scalable method for processing H. armigera survey trap samples in the U.S. and demonstrates the potential for applying ddPCR technology to screen and diagnose invasive species.