bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic control over the zitterbewegung of exciton–polaritons
Authors: Sedov E S , Sedova I E , Arakelian S M , Kavokin A V
Published: July 2020

The effect of the zitterbewegung consisting in trembling of trajectory of propagating particles may, in principle, be found in a variety of physical systems characterized by split kinetic energy dispersion branches. However, in a majority of material systems the effect is too weak to be observable. Specially designed semiconductor heterostructures representing optical microcavities with embedded quantum wells allow observing the zitterbewegung of exciton–polaritons that are optical cavity modes strongly hybridized with excitons in quantum wells. Here we show that external magnetic fields applied in the plane of the microcavity amplify this effect and allow for tuning the amplitude and the period of oscillations of polariton trajectories, thus being a convenient tool of control. These results pave the way towards realization of ballistic polariton transistors based on the spin–orbit effect, conceptually similar to Datta-and-Das transistors.
Physical properties of bulk, defective, 2D and 0D metal halide perovskite semiconductors from a symmetry perspective
Authors: Quarti Claudio , Katan Claudine , Even Jacky
Published: July 2020

Metal halide perovskite-based nanostructures, nanosheets and nanoparticles at the forefront, show attractive optoelectronic properties, suitable for photovoltaics and light emission applications. Achieving a sounded understanding of these basic electronic and optical properties represents therefore a crucial step for the full technological exploitation of this class of semiconductors. The rapidly expanding chemical engineering and their unusual structural diversity is fascinating but also challenging for a rational description on par with those well-known for conventional semiconductors. In this sense, group theory-based symmetry analyses offer a general and rigorous approach to understand the properties of various bulk perovskites and perovskite-based nanostructures. In this work, we review the electronic and optical response of metal halide perovskite semiconductors using symmetry analysis from group theory, recalling the main results for the prototypical cubic Pm-3m lattice of AMX3 bulk perovskites (where A is cation, M metal and X halide), then extending the analysis to three cases of technological interest: AMX3 nanoparticles, A4MX6 isolated octahedra, A2MX4 layered systems, and recently introduced deficient halide perovskites (d-HP). On the basis of symmetry arguments, we will stress analogies and differences in the electronic and optical properties of these materials, as induced by the spatial confinement and dimensionality. Meanwhile, we will take advantage of this analysis to discuss recent results and debates from the literature, as the energetics of dark/bright states in the band-edge exciton fine structure of perovskite nanoparticles and nanosheets. From the present work, we also anticipate that the band-edge exciton fine structure of d-HP does not present optically dark states, in striking contrast to AMX3 nanoparticles and layered perovskites, a fact that can have important consequences on the photophysics of these novel perovskitoids.
A practitioner behaviour change intervention for deprescribing in the hospital setting
Authors: Scott Sion , May Helen , Patel Martyn , Wright David J , Bhattacharya Debi
Published: July 2020

Background

hospital deprescribing trials have demonstrated marginal increases in deprescribing activity that are not sustained beyond the trial period. The hospital deprescribing implementation framework (hDIF) links barriers and enablers of deprescribing in hospital with 44 potential intervention components. This study aimed to support geriatricians and pharmacists to select and characterise hDIF components according to affordability, practicability, effectiveness, acceptability, safety and equity (APEASE) to design a deprescribing intervention in the English hospital setting.

Methods

we convened a modified Nominal Group Technique with a panel of nine geriatricians and pharmacists representing five English hospitals. Panel members selected and characterised intervention components from the hDIF based on the APEASE criteria. We set a consensus threshold of 80% agreement per APEASE criterion in order for the intervention component to be included.

Results

the panel selected five intervention components supporting engagement with deprescribing: an organisational action plan to prioritise deprescribing, two training activities to address pharmacists’ beliefs about negative deprescribing consequences, restructuring pharmacists’ working patterns to facilitate their contribution to deprescribing decisions, and sharing experiences of successfully engaging patients/family in deprescribing conversations to support others to do the same. A sixth component was selected to sustain engagement with deprescribing through measuring and sharing deprescribing activity achieved between teams.

Conclusions

deprescribing interventions targeting geriatricians’ and pharmacists’ behaviour in the English hospital context should include the six characterised components. A component to sustain deprescribing activity is a notable omission from previously reported deprescribing interventions and may explain their failure to maintain efficacy beyond the short-term trial period.
Substantial intraspecific genome size variation in golden-brown algae and its phenotypic consequences
Authors: Čertnerová Dora , Škaloud Pavel
Published: July 2020

Background and Aims

While nuclear DNA content variation and its phenotypic consequences have been well described for animals, vascular plants and macroalgae, much less about this topic is known regarding unicellular algae and protists in general. The dearth of data is especially pronounced when it comes to intraspecific genome size variation. This study attempts to investigate the extent of intraspecific variability in genome size and its adaptive consequences in a microalgal species.

Methods

Propidium iodide flow cytometry was used to estimate the absolute genome size of 131 strains (isolates) of the golden-brown alga Synura petersenii (Chrysophyceae, Stramenopiles), identified by identical internal transcribed spacer (ITS) rDNA barcodes. Cell size, growth rate and genomic GC content were further assessed on a sub-set of strains. Geographic location of 67 sampling sites across the Northern hemisphere was used to extract climatic database data and to evaluate the ecogeographical distribution of genome size diversity.

Key Results

Genome size ranged continuously from 0.97 to 2.02 pg of DNA across the investigated strains. The genome size was positively associated with cell size and negatively associated with growth rate. Bioclim variables were not correlated with genome size variation. No clear trends in the geographical distribution of strains of a particular genome size were detected, and strains of different genome size occasionally coexisted at the same locality. Genomic GC content was significantly associated only with genome size via a quadratic relationship.

Conclusions

Genome size variability in S. petersenii was probably triggered by an evolutionary mechanism operating via gradual changes in genome size accompanied by changes in genomic GC content, such as, for example, proliferation of transposable elements. The variation was reflected in cell size and relative growth rate, possibly with adaptive consequences.
Avian Extinctions in an Isolated Tropical Wet-Forest Preserve, Ecuador
Authors: Leck Charles F.
Published: July 2020

The avifauna of a small forest island in lowland Ecuador was surveyed to detect recent extinctions. The 87-ha national forest, at Rio Palenque, has had serious declines in bird species numbers, even within the relatively short period of 1973-78. Among the 170 species of forest-dwelling birds, I found no recent records for 19 species, 25 had been last noted in 1975, and 15 presently have precariously low populations. Attributes of the species that had local extinctions included, in order of importance, large body size (predatory habits), general rarity (specialization), or declining populations throughout their range. Illegal hunting was related to the loss of two species at the preserve. The importance of large refuges is reaffirmed by this study.
Annual Productivity and Its Measurement in a Multi-Brooded Passerine, the Eastern Bluebird
Authors: Pinkowski Benedict C.
Published: July 2020

Breeding and demographic parameters are examined for 434 Eastern Bluebirds (Sialia sialis) attempting 324 nests in southeastern Michigan during 1968-1977. Nesting birds spent an average of 10.4 weeks (63.9% of a 16.2-week season) in the study area. Only 154 (35.5%) of the nesting birds remained for entire breeding seasons; these season-long residents averaged 2.14 nests/season and had a higher success rate (68.4%) and presumably greater productivity (5.6 young · pair−1 · season −1) than other birds because site fidelity depends on nesting success.

Although two seasonal peaks for egg-laying were observed, only 75 of 357 birds (21.0%) successfully raised two broods. Evidence is presented to suggest that birds observed for only part of a season initiated nests at the same rate while in and not in the study area, so that an average annual productivity value of 5.0 young · pair−1 · season −1 is calculated for all nesting birds from the observed success rate (57.1%) and mean length of stay in the area. Estimated average productivity of yearlings (4.3 young · pair−1 · season −1) was lower than that of adults (5.7 young · pair−1 · season −1) although nesting success rates were similar in the two age groups.
Diet and Breeding Seasonality among a Population of Sharp-Tailed Munias, Lonchura striata, in Malaysia
Authors: Avery Michael L.
Published: July 2020

From April 1975 through March 1977, the food habits and breeding seasonality of a population of Sharp-tailed Munias (Lonchura striata) were studied in northwestern peninsular Malaysia. The abundance of munias on the study area varied in accordance with the 6-month rice-growing cycle there. The population peaked in March and September when juvenile birds were most numerous and when rice was most plentiful. Field observations and stomach analyses showed that the munias ate rice and the green filamentous alga, Spirogyra, almost exclusively. The primary periods of algae eating occurred in January and June-August, coinciding with the munias' two peak periods of reproductive activity, as determined by gonadal examination. Apparently munias on the study area ate Spirogyra as a source of protein to enable them to become physiologically ready for breeding, much as othe tropical bird species eat insects. Thus, unlike other species, Sharp-tailed Munias' breeding seasonality is determined by manmade cycles of rice cultivation rather than by natural cycles of rain and insect abundance.
Movements of Adult and Juvenile Bananaquits within a Morph-Ratio Cline
Authors: Wunderle Joseph M.
Published: July 2020

Adult and juvenile Bananaquits (Coereba flaveola) were captured and banded at nine different sites in southern Grenada in August-October 1976, 1977, and 1978. The proportion of black morphs decreased to seaward on Point Saline. The morph-ratio cline was steeper for adults than for juveniles, because juveniles move greater distances than postbreeding adults. Home-range sizes of adults are larger during the dry season than in the wet season, which under some circumstances can bring about temporal changes in the steepness of a cline.
Song Pattern Variation in the Sage Sparrow (Amphispiza belli): Dialects or Epiphenomena?
Authors: Wiens John A.
Published: July 2020

I investigated variation in the songs of Sage Sparrows (Amphispiza belli) breeding in the northwestern Great Basin over a 3-yr period. Individuals sang a single song type, which did not change during the day, through the breeding season, or between years. Although different individuals and populations differed in song parameters such as duration, delivery rate, and notes and note types per song, these variations exhibited no overall patterns with respect to geography or habitat. Similarity matrices based upon the sequential arrangement of note types in songs were used to draw comparisons within and between populations. Within-population vocal similarity of individuals varied considerably, from populations in which most neighboring individuals sang similar or identical songs to situations in which most individuals sang quite different songs; in one population, song variation was arrayed in "neighborhoods" of 3-5 individuals sharing similar songs, which differed markedly from those of adjacent clusters of individuals.

Song variation between populations was significantly greater than that within populations. Some populations located close to one another shared many song elements and patterns, but other nearby populations were totally different and showed greater similarity with populations located some distance away. The degree of song similarity between populations was neither a simple function of the physical distance between the populations, nor was it related to the distribution of topographic barriers in this region. Populations with greater between-individual dissimilarity in song patterns were also more variable from one year to the next and occurred in habitats of lower vegetation stature and greater patchiness. Generally, however, the patterns of vocal variation within and between populations were unrelated to features of habitat structure, to the densities of Sage Sparrows or of other coexisting species, or to avian community attributes.

I suggest that Sage Sparrows may have a simple, single-song repertoire because the song serves simple functions, and selection favoring a more elaborate song may be absent. The variety of patterns of within- and between-population vocal similarity may be associated with differences in population turnover rates, song ontogeny, dominance relationships, and dispersal, all of which require documentation to establish the foundations of vocal variation in this system (and others). The variety of population patterns, however, argues against a simplistic categorization of this species as dialectal or nondialectal. Much of the variation that is expressed may be a consequence of chance events and represents "epiphenomena" that are random with respect to natural selection.
Diabetes medications and risk of Parkinson’s disease: a cohort study of patients with diabetes
Authors: Brauer Ruth , Wei Li , Ma Tiantian , Athauda Dilan , Girges Christine , Vijiaratnam Nirosen , Auld Grace , Whittlesea Cate , Wong Ian , Foltynie Tom
Published: July 2020

The elevated risk of Parkinson’s disease in patients with diabetes might be mitigated depending on the type of drugs prescribed to treat diabetes. Population data for risk of Parkinson’s disease in users of the newer types of drugs used in diabetes are scarce. We compared the risk of Parkinson’s disease in patients with diabetes exposed to thiazolidinediones (glitazones), glucagon-like peptide-1 (GLP-1) receptor agonists and dipeptidyl peptidase 4 (DPP4) inhibitors, with the risk of Parkinson’s disease of users of any other oral glucose lowering drugs. A population-based, longitudinal, cohort study was conducted using historic primary care data from The Health Improvement Network. Patients with a diagnosis of diabetes and a minimum of two prescriptions for diabetes medications between January 2006 and January 2019 were included in our study. The primary outcome was the first recording of a diagnosis of Parkinson’s disease after the index date, identified from clinical records. We compared the risk of Parkinson’s disease in individuals treated with glitazones or DPP4 inhibitors and/or GLP-1 receptor agonists to individuals treated with other antidiabetic agents using a Cox regression with inverse probability of treatment weighting based on propensity scores. Results were analysed separately for insulin users. Among 100 288 patients [mean age 62.8 years (standard deviation 12.6)], 329 (0.3%) were diagnosed with Parkinson’s disease during the median follow-up of 3.33 years. The incidence of Parkinson’s disease was 8 per 10 000 person-years in 21 175 patients using glitazones, 5 per 10 000 person-years in 36 897 patients using DPP4 inhibitors and 4 per 10 000 person-years in 10 684 using GLP-1 mimetics, 6861 of whom were prescribed GTZ and/or DPP4 inhibitors prior to using GLP-1 mimetics. Compared with the incidence of Parkinson’s disease in the comparison group (10 per 10 000 person-years), adjusted results showed no evidence of any association between the use of glitazones and Parkinson’s disease [incidence rate ratio (IRR) 1.17; 95% confidence interval (CI) 0.76–1.63; P = 0.467], but there was strong evidence of an inverse association between use of DPP4 inhibitors and GLP-1 mimetics and the onset of Parkinson’s disease (IRR 0.64; 95% CI 0.43–0.88; P < 0.01 and IRR 0.38; 95% CI 0.17–0.60; P < 0.01, respectively). Results for insulin users were in the same direction, but the overall size of this group was small. The incidence of Parkinson’s disease in patients diagnosed with diabetes varies substantially depending on the treatment for diabetes received. The use of DPP4 inhibitors and/or GLP-1 mimetics is associated with a lower rate of Parkinson’s disease compared to the use of other oral antidiabetic drugs.
Catecholaminergic Modulation of Semantic Processing in Sentence Comprehension
Authors: Tan Yingying , Hagoort Peter
Published: July 2020

Catecholamine (CA) function has been widely implicated in cognitive functions that are tied to the prefrontal cortex and striatal areas. The present study investigated the effects of methylphenidate, which is a CA agonist, on the electroencephalogram (EEG) response related to semantic processing using a double-blind, placebo-controlled, randomized, crossover, within-subject design. Forty-eight healthy participants read semantically congruent or incongruent sentences after receiving 20-mg methylphenidate or a placebo while their brain activity was monitored with EEG. To probe whether the catecholaminergic modulation is task-dependent, in one condition participants had to focus on comprehending the sentences, while in the other condition, they only had to attend to the font size of the sentence. The results demonstrate that methylphenidate has a task-dependent effect on semantic processing. Compared to placebo, when semantic processing was task-irrelevant, methylphenidate enhanced the detection of semantic incongruence as indexed by a larger N400 amplitude in the incongruent sentences; when semantic processing was task-relevant, methylphenidate induced a larger N400 amplitude in the semantically congruent condition, which was followed by a larger late positive complex effect. These results suggest that CA-related neurotransmitters influence language processing, possibly through the projections between the prefrontal cortex and the striatum, which contain many CA receptors.
Social Capital and Large-Scale Agricultural Investments: An Experimental Investigation
Authors: Khadjavi Menusch , Sipangule Kacana , Thiele Rainer
Published: July 2020

Following the 2007–8 global food crisis, agricultural producers have invested in large tracts of land in developing countries. We investigate how the arrival of large-scale farms changes inter-personal trust and reciprocity, important components of social capital, in traditional villages. We elicit trust and reciprocal behaviour in villages that lie near large-scale farms and compare them with villages at a distance. Our data reveal greater trust in villages close to large-scale farms. Reciprocity is more frequent after farm employment. These results are likely driven by communal coping and reputation building. A natural field measure shows that trust correlates with public good sharing.
Improvement of the objective function in the velocity structure inversion based on horizontal-to-vertical spectral ratio of earthquake ground motions
Authors: Rong Mianshui , Li Xiaojun , Fu Lei
Published: July 2020

Given the improvements that have been made in the forward calculations of seismic noise horizontal-to-vertical spectral ratios (NHVSRs) or earthquake ground motion HVSRs (EHVSRs), a number of HVSR inversion methods have been proposed to identify underground velocity structures. Compared with the studies on NHVSR inversion, the research on the EHVSR-based inversion methods is relatively rare. In this paper, to make full use of the widely available and constantly accumulating strong-motion observation data, we propose an S-wave HVSR inversion method based on diffuse-field approximation. Herein, the S-wave components of earthquake ground motion recordings are considered as data source. Improvements to the objective function has been achieved in this work. An objective function with the slope term is introduced. The new objective function can mitigate the multisolution phenomenon encountered when working with HVSR curves with multipeaks. Then, a synthetic case is used to show the verification of the proposed method and this method has been applied to invert underground velocity structures for six KiK-net stations based on earthquake observations. The results show that the proposed S-wave EHVSR inversion method is effective for identifying underground velocity structures.
Lysine acetylation regulates the RNA binding, subcellular localization and inclusion formation of FUS
Authors: Arenas Alexandra , Chen Jing , Kuang Lisha , Barnett Kelly R , Kasarskis Edward J , Gal Jozsef , Zhu Haining
Published: July 2020

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the preferential death of motor neurons. Approximately 10% of ALS cases are familial and 90% are sporadic. Fused in sarcoma (FUS) is a ubiquitously expressed RNA-binding protein implicated in familial ALS and frontotemporal dementia (FTD). The physiological function and pathological mechanism of FUS are not well understood, particularly whether post-translational modifications play a role in regulating FUS function. In this study, we discovered that FUS was acetylated at lysine-315/316 (K315/K316) and lysine-510 (K510) residues in two distinct domains. Located in the nuclear localization sequence, K510 acetylation disrupted the interaction between FUS and Transportin-1, resulting in the mislocalization of FUS in the cytoplasm and formation of stress granule-like inclusions. Located in the RNA recognition motif, K315/K316 acetylation reduced RNA binding to FUS and decreased the formation of cytoplasmic inclusions. Treatment with deacetylase inhibitors also significantly reduced the inclusion formation in cells expressing ALS mutation P525L. More interestingly, familial ALS patient fibroblasts showed higher levels of FUS K510 acetylation as compared with healthy controls. Lastly, CREB-binding protein/p300 acetylated FUS, whereas both sirtuins and histone deacetylases families of lysine deacetylases contributed to FUS deacetylation. These findings demonstrate that FUS acetylation regulates the RNA binding, subcellular localization and inclusion formation of FUS, implicating a potential role of acetylation in the pathophysiological process leading to FUS-mediated ALS/FTD.
Wild salmonids are running the gauntlet of pathogens and climate as fish farms expand northwards
Authors: Vollset Knut Wiik , Lennox Robert J , Davidsen Jan Grimsrud , Eldøy Sindre Håvarstein , Isaksen Trond E , Madhun Abdullah , Karlsson Sten , Miller Kristina M
Published: July 2020

Salmon farming has multiplied from a side business of coastal farmers to one of the world's major aquaculture species. This has dramatically altered the disease dynamics between farmed and wild salmonids. As salmon fish farming has increased, new restrictions have been enforced to combat emerging density-dependent impacts of pathogen spillover. In most northern and arctic regions, the effects of pathogens from fish farms on wild salmonids have been minimal for two key reasons: (i) relative low density of fish farms in the north and (ii) cold water temperatures. However, both factors are set to change dramatically. On one side, there is an increasing interest in utilizing northern areas for fish farming due to limited capacity for expansion in mid-latitude regions. On the other side, climate change is rapidly changing these northern ecosystems. High-latitude regions inhabit some of the largest remaining wild Atlantic salmon populations in the world along with sea trout and Arctic charr. Wild salmonids in the north have most likely seldom been exposed to high infection pressure, and we question how these populations will cope with changes that are coming. We identify 12 research questions emerging from these imminent changes and discuss methodologies for addressing them. We conclude that policies related to fish farming must consider uncertainties with respect to pathogen dynamics in the north until these research questions are fully addressed.
Role of ultra-processed food in fat mass index between 6 and 11 years of age: a cohort study
Authors: Costa Caroline dos Santos , Assunção Maria Cecília Formoso , Loret de Mola Christian , Cardoso Juliane de Souza , Matijasevich Alicia , Barros Aluísio J D , Santos Iná S
Published: July 2020

Background

Ultra-processed food consumption and obesity have been highlighted as an important relationship to public health. We aimed to evaluate the association between ultra-processed food consumption and body fat from 6 to 11 years of age.

Methods

We assessed the association between ultra-processed food consumption (from food frequency questionnaires) and body fat (measured by air displacement plethysmography) between 6 and 11 years of age among participants of the Pelotas-Brazil 2004 Birth Cohort. The NOVA classification was used to classify foods according to the processing degree. Body fat was evaluated relative to the height using fat mass index (FMI). Generalized estimating equations were used to answer the main research question and mediation analyses were run to assess the direct and indirect effect of ultra-processed food in body fat.

Results

At fully adjusted analysis, an increase of 100 g in contribution from ultra-processed food to daily food intake at between 6 and 11 years of age was associated with a gain of 0.14 kg/m² in FMI in the same period; 58% of the total effect of ultra-processed food intake at 6 years (in grams) over the change in FMI from 6 to 11 years was mediated by its calorie content.

Conclusions

Ultra-processed food consumption was associated with an increase in body fat from childhood to early adolescence, and this association was not just due to the effect of ultra-processed food on calorie content.
Exposure to Moderate Glycosuria Induces Virulence of Group B Streptococcus
Authors: John Preeti P , Baker Brady C , Paudel Santosh , Nassour Lauren , Cagle Hayden , Kulkarni Ritwij
Published: July 2020

To explore whether glycosuria induces virulence of uropathogens, in turn facilitating urinary tract infection (UTI), we exposed group B Streptococcus (GBS) strain 10/84 to human urine plain or with 300 mg/dL glucose (mimicking moderate glycosuria). Exposure to moderate glycosuria significantly augmented bacterial growth, kidney bacterial burden in a mouse model of ascending UTI, and virulence characteristics and expression of corresponding genes. Exposure to glycosuria increased GBS adherence to human bladder epithelial cell line and expression of corresponding PI2a fimbrial gene, antimicrobial peptide LL-37 resistance and bacterial surface charge modulating dltA, and GBS hemolytic ability and expression of genes encoding pore-forming toxins.
Determination of Imidacloprid and Benzimidazole Residues in Fruits and Vegetables by Liquid Chromatography–Mass Spectrometry after Ethyl Acetate Multiresidue Extraction
Authors: Fernández-Alba Amadeo R , Tejedor Ana , Agüera Ana , Contreras Mariano , Garrido Juan
Published: July 2020

A simple and sensitive method based on liquid chromatography–atmospheric pressure ionization–mass spectrometry is described for the determination of 4 benzimidazole pesticides (carbendazim, thiabendazole, benomyl, and thiophanate-methyl) and imidacloprid in vegetables and fruits. Food samples were typically extracted with ethyl acetate to draw the analytes into the organic phase. No cleanup step was necessary before injection into the liquid chromatographic (LC) system with electrospray mass spectrometric detection. The analytes were separated on a reversed-phase C8LC column. Limits of detection for the compounds were in the μg/L range. Results are reported for validation studies with fortified pear and tomato samples and for residues of the target compounds found in the pesticide residue monitoring program during 1998.
Determination of Aluminium and Chromium in Slurried Baby Food Samples by Electrothermal Atomic Absorption Spectrometry
Authors: Viñas Pilar , Pardo-Martínez Mercedes , Hernández-Córdoba Manuel
Published: July 2020

Electrothermal atomic absorption spectrometry was used to determine aluminium and chromium in different types of baby foods. Samples without previous treatment were introduced into the atomizer as suspensions, which were prepared in a medium containing 0.1% (w/v) Triton X-100 (for chromium) or 10% (v/v) ethanol (for aluminium), 5% (v/v) concentrated hydrogen peroxide, and 0.5% (v/v) concentrated nitric acid. The slurries were homogenized with a potter and introduced directly into the furnace. The presence of nitric acid allowed a substantial amount of analyte to be extracted to the liquid phase. No matrix effect was observed and aqueous standard solutions were used for calibration. The detection limits were 4 and 50 pg for chromium and aluminium, respectively; characteristic masses were 3.8 pg for chromium and 18 pg for aluminium. Reliability of the procedures was checked by statistically comparing the results with those obtained with a previous microwave oven mineralization stage and by analyis of several certified reference materials. Values for the aluminium content ranged between 0.4 and 3.0 μg/g, and for chromium between 0.003 and 0.06 μg/g.
Trace Analysis of Microcystins in Environmental Samples
Authors: Harada Ken-Ichi , Kondo Fumio , Tsuji Kiyomi
Published: July 2020

Microcystins, the cyclic heptapeptide toxins produced by cyanobacteria such as Microcystis sp., show potent hepatotoxicity and tumor-promoting activity through inhibition of protein phosphatases 1 and 2A. A toxic incident resulting in the death of 50 people in Brazil in 1996 was due to microcystins in water used for hemodialysis. Microcystins are now threatening human health and life, but many problems associated with microcystins remain unsolved. This report describes how to analyze trace amounts of microcystins in complicated matrixes such as liver tissue, lake water, and sediments.
Protein Immunoassay Methods for Detection of Biotech Crops: Applications, Limitations, and Practical Considerations
Authors: Stave James W
Published: July 2020

Immunoassay methods are available for detection and quantitation of proteins expressed by most biotechnology-derived crops in commercial production. The 2 most common test formats are enzyme-linked immunosorbent assay (ELISA) and immunochromatographic (lateral flow) strip tests. Two ELISA methods, one for Roundup Ready soybeans and one for MON810 Cry1Ab corn, were the subject of large international collaborative studies and were demonstrated to quantitatively determine the concentrations of biotech crops in samples of ground grain. Quantitative ELISA methods are also useful for analysis of processed fractions of agricultural commodities such as soybean toasted meal or corn flour. Both strip tests and ELISAs for biotech crops are currently being used on a large scale in the United States to manage the sale and distribution of grain. In these applications, tests are used to determine if the concentration of biotech grain is above or below specified threshold limits. Using existing U.S. Department of Agriculture sampling techniques, the reliability of the threshold determination is expressed in terms of statistical confidence rather than analytical precision. Combining the use of protein immunoassays with Identity Preservation systems provides an effective means of characterizing the raw and processed agricultural inputs to the food production system in a way that allows food producers to comply with labeling laws.
State of the Art and Limitations of Quantitative Polymerase Chain Reaction
Authors: Wiseman Gordon
Published: July 2020

Consequential to the implementation of European Commission (EC) Regulation 1139/98, EC Regulation 49/2000, and EC Regulation 50/2000 has been the need to measure accurately the levels of the genetically modified (GM) species Roundup Ready Soya and Bt 176 Maize that are present in food. Analytical methods to detect and quantitate these transgenic species have received much attention particularly with respect to the deminimus threshold of 1% for their presence in materials derived from non-GM identity-preserved (IP) supplies. The relative advantages and limitations of threshold analysis by double-competitive polymerase chain reaction (PCR) and quantitative real-time PCR are discussed in their application to the quantitative analysis of processed foods. Consideration is also given to other factors involved in the analyses that affect the performance of quantitative procedures, and to the many uncertainties involved in the precision of a reported analytical result.
Determination of Available Phenolic Compounds in Soils by Liquid Chromatography with Solid-Phase Extraction
Authors: Matějíček David , Klejdus Bořivoj , Kubáň Vlastimil
Published: July 2020

A fast, selective, and sensitive liquid chromatographic (LC) method was developed for determination of derivatives of benzoic and cinnamic acids (gallic, protocatechuic, 2,3,4–trihydroxybenzoic, 4-hydroxybenzoic, vanillic, caffeic, syringic, 4-coumaric, ferulic, sinapic, benzoic, 2-coumaric, cinnamic acids, and 4-hydroxybenzaldehyde and vanillin) in soil samples. The method for sample pretreatment is based on temperature-controlled extraction with water (pH 5.6) for 60 min. Extracts were preconcentrated and purified by solid-phase extraction on OASIS HLB sorbent, with subsequent separation and quantification of individual substances by LC with UV diode-array detection. Limits of detection (3 signal-to-noise LODs) better than 65 ng/g (dry weight) and recoveries from 88 to 99% were found for each compound at absorbance 280 nm. The method was used for determination of bioavailable phenolic compounds in different soil samples.
Determination of Diclofenac Sodium in Eagle's Minimum Essential Medium with Earle's Balanced Salt Solution
Authors: Lopes Patrícia S , Kaneko Telma M , Takano Carolina Y , Lacerda Aurea C L , Latorre Leandro R , Kato Massuo J
Published: July 2020

A validated method was developed for determination of diclofenac sodium, considered a model hydrophilic drug for in vitro permeation studies, in Eagle's Minimum Essential Medium (MEM) with Earle's balanced salt solution. Liquid chromatography was used to determine diclofenac sodium. This method was developed with a reversed-phase column Supercosil LC 18, DB 25 cm × 4.5 mm; the mobile phase was methanol with 3% (v/v) acetic acid–Milli-Q water (74 + 26), and detection was at 283 nm. The detection and quantitation limits were 2.41 × 10–8 and 3.31 × 10–5 μg/μL, respectively. The accuracy within-day (n = 3) and day-to-day (n = 7) was 98.83%; the mean variation coefficient for inter- (n = 7) and intraday precision (n = 3) was 12.20%, thus, not exceeding 15%. This method can be used as an analytical procedure for the determination of diclofenac sodium in MEM for in vitro permeation studies.
Analysis of Cholesterol Oxidation Products in Biological Samples
Authors: Diczfalusy Ulf
Published: July 2020

Cholesterol oxidation products, or oxysterols, have gained increased attention since it was suggested that they participate in cell signaling as ligands for the nuclear receptors liver X receptor α and β. In addition, oxysterols serve as important intermediates in bile acid biosynthesis and are also involved in cholesterol transport. Several studies have suggested that certain oxysterols may be used as markers for oxidative stress, and still other oxysterols may be of use in diagnosing neurological diseases. This broad spectrum of functions in health and disease has created a demand for accurate and reliable methods to measure oxysterols in complex biological matrixes. At present, the most reliable and sensitive method for oxysterol determination in biological materials is isotope-dilution gas chromatography-mass spectrometry using deuterium-labeled internal standards. With this technique, the major oxysterols in human blood plasma and atherosclerotic plaques have been carefully determined. The knowledge of oxysterol contents in other tissues and organs is still very scarce. As oxysterols are found to participate in an increasing number of cellular events, it is obvious that improved methods are needed for their analysis to understand their roles in the living cell.
Macroscopic and Microscopic Authentication of Chinese and North American Species of Ephedra
Authors: Joshi Vaishali C , Khan Ikhlas
Published: July 2020

Ephedra sinica Stapf or Ma Huang has been used in traditional Chinese medicine for over 5000 years as a bronchodilating and stimulatory agent. In the West, it is popularly used in dietary supplements for weight loss and to enhance athletic performance. Adverse events have been reported following consumption of dietary supplements containing ephedrine alkaloids. There are about 50 known species of Ephedra. The ratio of ephedrine to other alkaloids varies from species to species; all North American species lack alkaloids. The method commonly used in the dietary supplement industry for botanical authentication is to analyze the product for the presence of chemical markers known to be present in the specific herb. However, this method does not ensure that the product contains authentic herb, especially if it has been spiked with chemical marker compounds. In the trade and raw drug market, Ephedra is available in the form of stem cuttings or powders, without any vouchers, thus making identification of the species difficult. Using light microscopy, we can detect the presence of Ephedra herb, even in powder form, and identify within certain limits its geographical origin. Identification of Chinese and North American species of Ephedra has been made easier by developing a key using leaf and internode length as key identification characters.
Influence of Sampling Methodology on Reported Incidence of Salmonella in Poultry
Authors: Fletcher Daniel L
Published: July 2020

Salmonella is a major pathogen associated with poultry food products. Over the past 20 years, pressure to reduce human illness from poultryrelated salmonellosis has resulted in intensive research activity as well as stronger regulatory standards in Europe, North America, and, because of international trade policies, throughout the world. In the United States, implementation of a Hazard Analysis Critical Control Point-based inspection program has been credited with reducing the incidence of Salmonella-positive carcasses from approximately 20 to 10. Since 1998, however, the reported incidence of Salmonella in retail poultry from 12 countries implementing similar pathogen reduction programs, including the United States, has averaged 29 positive for Salmonella. Although these reports examined products at retail outlets and used a variety of sampling methodologies, these results appear to contradict the U.S. Department of Agriculture claims for Salmonella reduction. The purpose of this review is to examine this contradiction with a focus on the potential impact of sampling methodology on reported incidences of Salmonella.
Overview of Affinity Biosensors in Food Analysis
Authors: Patel Pradip D
Published: July 2020

The 4 major driving forces that are expected to lead to increased use of affinity biosensors that meet crucial industrial test specifications, e.g., fast, reliable, cost-effective, and use of low-skilled personnel, are (1) strict legislative framework, e.g., recent changes proposed to the European food safety and hygiene legislation, EC No. 178/2002; (2) industrial shift from quality control to quality assurance procedures, e.g., Hazard Analysis Critical Control Point, ensuring effective positioning in the global competitive trade; (3) just-in-time production resulting in right product every time; and (4) consumer demand for safe and wholesome products. The affinity biosensors field has expanded significantly over the past decade, with a projected global biosensors market growth from $6.1 billion in 2004 to $8.2 billion in 2009, representing major industrial sectors (e.g., Pharma, Medicare, and Food). This brief review is targeted to affinity biosensors developed for the food industry and includes research and development leading to biosensors for microbiological and chemical analytes of industrial concern, commercial biosensors products on the market, and examples of future prospects in this diagnostic field.
Reflectometric Cutinase Assay for Rapid Screening of Contaminants and Residues of Insecticidal Organophosphates and Carbamates
Authors: Walz Ingrid , Schwack Wolfgang
Published: July 2020

Because of the extensive use of insecticides in agriculture, there is an increasing demand for rapid analytical methods for residues in food and feed control. To meet this need, a completely new application of the reflectometric lipase test (Reflectoquant, Merck) was developed. By using the cutinase-induced reaction of the substrate 5-bromo-4-chloro-3-indoxyl caprylate on the test strips, residues of organophosphates and carbamates can be determined on the basis of enzyme inhibition in a fast and inexpensive way. With this technique, we investigated the inhibition effects of representative insecticides, i.e., chlorpyrifos oxon, paraoxon, and carbaryl. The bimolecular inhibitory rate constants (ki) were found to agree well with those obtained by a previously described spectrophotometric cutinase assay in the microtiter-plate format. Recoveries determined with the strip test from spiked samples compared well with those obtained by both the cutinase microtiter-plate assay and liquid chromatography/mass spectrometry.
A Capillary Zone Electrophoretic Method for Simultaneous Determination of Seven Drugs in Pharmaceuticals and in Human Urine
Authors: Solangi Amber R , Bhanger Muhammad I , Memon Saima Q , Khuhawar Muhammad Y , Mallah Arfana
Published: July 2020

A simple, sensitive, and novel method has been developed and validated for the separation and simultaneous quantitation of seven structurally different drugspipemidic acid and ofloxacin quinolone antibiotics, pseudoephedrine decongestant, piroxicam anti-inflammatory, thiamin, pyridoxine, and cobalaminin a mixture by capillary zone electrophoresis. Factors affecting the separation were pH, concentration of buffer, and applied voltage. Separation was carried out in <9 min with a 50 mM sodium tetraborate buffer, pH 10, and an applied voltage of 30 kV in an uncoated silica capillary tube. The carrier electrolyte gave baseline separation with good resolution, reproducibility, and accuracy. Calibration plots were linear over at least three orders of magnitude of analyte concentrations, and the lower LODs were within the range of 15 g/mL. Detection was performed by UV absorbance at 230 nm. The method was validated for the analysis of drugs in pharmaceutical preparations and in urine samples with RSD of 0.52.4 and recovery of >99.
The origins of nearly coplanar, non-resonant systems of close-in super-Earths
Authors: Esteves Leandro , Izidoro André , Raymond Sean N , Bitsch Bertram
Published: July 2020

Some systems of close-in ‘super-Earths’ contain five or more planets on non-resonant but compact and nearly coplanar orbits. The Kepler-11 system is an iconic representative of this class of system. It is challenging to explain their origins given that planet–disc interactions are thought to be essential to maintain such a high degree of coplanarity, yet these same interactions invariably cause planets to migrate into chains of mean motion resonances. Here, we mine a large data set of dynamical simulations of super-Earth formation by migration. These simulations match the observed period ratio distribution as long as the vast majority of planet pairs in resonance become dynamically unstable. When instabilities take place resonances are broken during a late phase of giant impacts, and typical surviving systems have planet pairs with significant mutual orbital inclinations. However, a subset of our unstable simulations matches the Kepler-11 system in terms of coplanarity, compactness, planet-multiplicity, and non-resonant state. This subset has dynamical instability phases typically much shorter than ordinary systems. Unstable systems may keep a high degree of coplanarity post-instability if planets collide at very low orbital inclinations (≲1○) or if collisions promote efficient damping of orbital inclinations. If planetary scattering during the instability takes place at low orbital inclinations (i ≲ 1○), orbital inclinations are barely increased by encounters before planets collide. When planetary scattering pumps orbital inclinations to higher values (≳1○) planets tend to collide at higher mutual orbital inclinations, but depending on the geometry of collisions mergers’ orbital inclinations may be efficiently damped. Each of these formation pathways can produce analogues to the Kepler-11 system.
Migrating low-mass planets in inviscid dusty protoplanetary discs
Authors: Hsieh He-Feng , Lin Min-Kai
Published: July 2020

Disc-driven planet migration is integral to the formation of planetary systems. In standard, gas-dominated protoplanetary discs, low-mass planets or planetary cores undergo rapid inwards migration and are lost to the central star. However, several recent studies indicate that the solid component in protoplanetary discs can have a significant dynamical effect on disc–planet interaction, especially when the solid-to-gas mass ratio approaches unity or larger and the dust-on-gas drag forces become significant. As there are several ways to raise the solid abundance in protoplanetary discs, for example through disc winds and dust trapping in pressure bumps, it is important to understand how planets migrate through a dusty environment. To this end, we study planet migration in dust-rich discs via a systematic set of high-resolution, two-dimensional numerical simulations. We show that the inwards migration of low-mass planets can be slowed down by dusty dynamical corotation torques. We also identify a new regime of stochastic migration applicable to discs with dust-to-gas mass ratios of ≳0.3 and particle Stokes numbers ≳0.03. In these cases, disc–planet interaction leads to the continuous development of small-scale, intense dust vortices that scatter the planet, which can potentially halt or even reverse the inwards planet migration. We briefly discuss the observational implications of our results and highlight directions for future work.