Stability of Wheat Floret Metabolites during Untargeted Metabolomics Studies

A typical metabolomic analysis consists of a multi-step procedure. Variation can be introduced in any analysis segment if proper care in quality assurance is not taken, thus compromising the final results. Sample stability is one of those factors. Although sophisticated studies addressing sample decay over time have been performed in the medical field, they are emerging in plant metabolomics. Here, we focus on the stability of wheat floret extracts on queue inside an auto-injector held at 25 °C. The objective was to locate an analytical time window from extraction to injection with no significant difference occurring in the sample. Total ion current chromatograms, principal component analysis, and volcano plots were used to measure changes in the samples. Results indicate a maximum work window time of 7:45 h for Steele-ND wheat methanolic extractions in an auto-sampler at 25 °C. Comparisons showed a significant gradual increase in the number and intensity of compounds observed that may be caused by the degradation of other molecules in the sample extract. The approach can be applied as preliminary work in a metabolite profiling study, helping to set the appropriate workload to produce confident results.

Analytical time-dependent distributions for gene expression models with complex promoter switching mechanisms

Classical gene expression models assume exponential switching time distributions between the active and inactive promoter states. However, recent experiments have shown that many genes in mammalian cells may produce non-exponential switching time distributions, implying the existence of multiple promoter states and molecular memory in the promoter switching dynamics. Here we analytically solve a gene expression model with random bursting and complex promoter switching, and derive the time-dependent distributions of the mRNA and protein copy numbers, generalizing the steady-state solutions obtained in [SIAM J. Appl. Math. 72, 789-818 (2012)] and [SIAM J. Appl. Math. 79, 1007-1029 (2019)]. Using multiscale simplification techniques, we find that molecular memory has no influence on the time-dependent distribution when promoter switching is very fast or very slow, while it significantly affects the distribution when promoter switching is neither too fast nor too slow. By analyzing the dynamical phase diagram of the system, we also find that molecular memory in the inactive gene state weakens the transient and stationary bimodality of the copy number distribution, while molecular memory in the active gene state enhances such bimodality.

Combined Zircon/Apatite U-Pb and Fission-Track Dating by LA-ICP-MS and Its Geological Applications: An Example from the Egyptian Younger Granites

Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) is classically used in U-Pb dating to measure U and Pb isotopic concentrations. Recently, it has become frequently used in fission-track (FT) chronometry too. As an advantage, the U-Pb and FT double dating will enable efficiently determining the crystallization ages and the thermo-tectonic history concurrently as samples volume, analytical time, efforts, and cost will be greatly reduced. To demonstrate the validity of this approach, a Younger granite (Ediacaran age) sample from North Eastern Desert (NED), Egypt was analyzed for U-Pb and FT double dating. The integration of multiple geochronologic data yielded a zircon U-Pb crystallization age of 599 ± 30 Ma, after emplacement, the rock cooled /uplifted rapidly to depths of 9–14 km as response to the post-Pan African Orogeny erosional event as indicated by apatite U-Pb age of 474 ± 9 Ma. Afterwards, the area experienced a slow cooling/exhumation for a short period, most-likely as response to denudation effect. During the Devonian, the area was rapidly exhumed to reach depths of 1.5–3 km as response to the Hercynian tectonic event, as indicated by a zircon FT age of 347 ± 16 Ma. Then the studied sample has experienced a relatively long period of thermal stability between the Carboniferous and the Eocene. During the Oligocene-Miocene, the Gulf of Suez opening event affected the area by crustal uplift to its current elevation. This integration of Orogenic and thermo-tectonic information reveals the validity, efficiency, and importance of double dating of U-Pb and FT techniques using LA-ICP-MS methodology.

Application and Construction of Microbial Biosensors in Chemical Forensics

<p>Forensic toxicologists are often required to rapidly determine if a suspicious substance, such as a white powder, contain toxins. Preliminary tests usually include screens for a wide range of 'Potentially Toxic Chemicals' (PTCs) such as cyanide, pesticides, herbicides, medicinal and illicit drugs. Subsequent analyses are generally very time-consuming and costly. Any protocol screening for a range of PTC's, prior to more robust chemical analysis, could therefore save significant analytical time. Microbial biosensors are ideal biological tools that can be utilised for these purposes. In vivo bioassays were developed for a range of PTCs using a suite of microbial biosensors, in a variety of complex matrices including water, white powders, soils and vomit to determine the effect of matrix complexities on the biosensors, as well as the toxins. The lux biosensor, Escherichia coli HB101 pUCD607, showed an EC50, (where EC50 is the effective concentration of toxin causing 50% reduction in bioluminescence), of cyanide in water of 20 mg/L. This biosensor still detected cyanide, in talc and flour, at EC50 values of 589 mg/L and 700 mg/L respectively. Vibrio harveyi showed good sensitivity to cyanide in initial water bioassays with an EC50 of 9.66 mg/L. The V. harveyi biosensor did not detect cyanide spiked in talc or flour when tested up to a maximum concentration of 10,000 mg/L. The Mycena citricolor ATCC 34884 fungal biosensor, showed lower sensitivity levels however it detected the presence of sodium monofluoroacetate (1080) at a concentration 1000 mg/L. Preliminary investigation of a novel, faster, solid-phase sample preparation method was also undertaken and its potential proven, particularly in PTC spiked white powders. Here the biosensor showed sensitivity to arsenate, arsenite, copper, cyanide and PCP at 1000 mg/L.This project highlighted the inability of current biosensors to reliably detect 1080 and the difficulty in constructing a specific biosensor. The utilisation of a reliable vector and inducible promoter are pivotal in biosensor construction.</p>

Application and Construction of Microbial Biosensors in Chemical Forensics

<p>Forensic toxicologists are often required to rapidly determine if a suspicious substance, such as a white powder, contain toxins. Preliminary tests usually include screens for a wide range of 'Potentially Toxic Chemicals' (PTCs) such as cyanide, pesticides, herbicides, medicinal and illicit drugs. Subsequent analyses are generally very time-consuming and costly. Any protocol screening for a range of PTC's, prior to more robust chemical analysis, could therefore save significant analytical time. Microbial biosensors are ideal biological tools that can be utilised for these purposes. In vivo bioassays were developed for a range of PTCs using a suite of microbial biosensors, in a variety of complex matrices including water, white powders, soils and vomit to determine the effect of matrix complexities on the biosensors, as well as the toxins. The lux biosensor, Escherichia coli HB101 pUCD607, showed an EC50, (where EC50 is the effective concentration of toxin causing 50% reduction in bioluminescence), of cyanide in water of 20 mg/L. This biosensor still detected cyanide, in talc and flour, at EC50 values of 589 mg/L and 700 mg/L respectively. Vibrio harveyi showed good sensitivity to cyanide in initial water bioassays with an EC50 of 9.66 mg/L. The V. harveyi biosensor did not detect cyanide spiked in talc or flour when tested up to a maximum concentration of 10,000 mg/L. The Mycena citricolor ATCC 34884 fungal biosensor, showed lower sensitivity levels however it detected the presence of sodium monofluoroacetate (1080) at a concentration 1000 mg/L. Preliminary investigation of a novel, faster, solid-phase sample preparation method was also undertaken and its potential proven, particularly in PTC spiked white powders. Here the biosensor showed sensitivity to arsenate, arsenite, copper, cyanide and PCP at 1000 mg/L.This project highlighted the inability of current biosensors to reliably detect 1080 and the difficulty in constructing a specific biosensor. The utilisation of a reliable vector and inducible promoter are pivotal in biosensor construction.</p>

ABOUT THE ANALYTICAL SOLUTION OF THE EQUATION OF IMPACT FORCE OF TWO ELASTIC BODIES

A nonlinear differential equation of the force of direct central impact of elastic bodies of revolution, which have a singular point on the boundary contact surface, where its curvature is infinite, is compiled. To determine the coefficients of the equation and the order of its power nonlinearity, the well-known solution of the axisymmetric contact problem of the theory of elasticity, constructed by I. Ya. Shtaermann, is used. In the formulation of the dynamic problem, the classical assumptions of the theory of quasi-static impact proposed by H. Hertz were also used. The constituted equation of impact force is reduced to the Bernoulli equation and its closed analytical solution is constructed, which is expressed in terms of the Ateb-sine. Analytical time dependences of the impact force and the convergence of the centers of mass of elastic bodies are obtained. Compact formulas have been derived for calculating the maxima of these quantities, as well as the durations of the process of compression and impact of bodies. Compact approximations of Ateb-sine by elementary functions are proposed. Thanks to these approximations, it was possible to obtain a fairly simple analytical sweep in time of a fast-flowing mechanical process. Traditionally, in other works such a scan was obtained by numerical solution of the corresponding integral equations that determine the force of an impact. Examples of calculations are given in which the influence of various factors on the main characteristics of a body impact with a small initial velocity is investigated. The limitation on the collision rate is due to the elastic formulation of the problem, where the possibility of plastic deformations is excluded. As a result of this formulation, the need to determine the rate of recovery rate has disappeared, for it is equal to one. Comparison of numerical results is carried out, to which the obtained analytical solutions and the numerical integration of the impact force equation on a computer lead. Small divergences of the results confirmed the accuracy of the derived calculation formulas. Numerical results relate to the impact of a steel body on a fixed rubber half-space, the analogue of which is observed in practice when falling pieces of mineral raw materials on the rolls of a vibration classifier lined with rubber.

Spotlight influenza: Influenza surveillance before and after the introduction of point-of-care testing in Denmark, season 2014/15 to 2018/19

Background In Denmark, influenza surveillance is ensured by data capturing from existing population-based registers. Since 2017, point-of-care (POC) testing has been implemented outside the regional clinical microbiology departments (CMD). Aim We aimed to assess influenza laboratory results in view of the introduction of POC testing. Methods We retrospectively observed routine surveillance data on national influenza tests before and after the introduction of POC testing as available in the Danish Microbiological Database. Also, we conducted a questionnaire study among Danish CMD about influenza diagnostics. Results Between the seasons 2014/15 and 2018/19, 199,744 influenza tests were performed in Denmark of which 44,161 were positive (22%). After the introduction of POC testing, the overall percentage of positive influenza tests per season did not decrease. The seasonal influenza test incidence was higher in all observed age groups. The number of operating testing platforms placed outside a CMD and with an instrument analytical time ≤ 3 h increased after 2017. Regionally, the number of tests registered as POC in the Danish Microbiological Database and the number of tests performed with an instrument analytical time ≤ 3 h or outside a CMD partially differed. Where comparable (71% of tests), the relative proportion of POC tests out of all tests increased from season 2017/18 to 2018/19. In both seasons, the percentage of positive POC tests resulted slightly lower than for non-POC tests. Conclusion POC testing integrated seamlessly into national influenza surveillance. We propose the use of POC results in the routine surveillance of seasonal influenza.

Between Cooperation and/or Co-optation and Confrontation: Civil Society-State Relations in Ethiopia, Since 1991 up to 2018

By qualitatively drawing on relevant empirical and secondary data sources, the present study sought to investigate the relationship and the practice between the Ethiopian state and csos through the illustration of different relationship patterns, i.e. cooperation and/or co-optation and confrontation, between the two actors and the implications thereof for the imperative of democratization in the country. The study primarily analyzed two supplementary notions: the politico-legal changes in the governance of Ethiopian csos, between 1991 and 2018, on the one hand, and the strategies employed by cso actors to deal with such changes in the same period, on the other hand. The analysis could be further divided into two analytical time periods i.e., the first is from 1991 up to 2005 and the second is from 2005 up to 2018. In doing so, the study found out that the state-civil society relations in Ethiopia since 1991 was more complicated than implied by the liberal discourse, and reflected a continuum of accommodation and confrontation dynamics. The study concluded by arguing that the commonly held dichotomy which polarized the relation between the state and csos as a whole may have overlooked the nature of relationship between the two actors, which can range from overt and hidden tensions and active hostility to cooperation and collaboration, depending on various factors across time and space.

Ultra-fast, high throughput and inexpensive detection of SARS-CoV-2 seroconversion

ABSTRACTA technique allowing high throughput, fast and low-cost quantitative analysis of human IgG antibodies reacting to SARS-CoV-2 antigens will be required to understand the levels of protecting antibodies in the population raised in response to infections and/or to immunization. We described previously a fast, simple, and inexpensive Ni2+ magnetic bead immunoassay which allowed detection of human antibodies reacting against the SARS-CoV-2 nucleocapsid protein using a minimal amount of serum or blood. A major drawback of the previously described system was that it only processed 12 samples simultaneously. Here we describe a manually operating inexpensive 96 well plate magnetic extraction / homogenization process which allows high throughput analysis delivering results of 96 samples in chromogenic format in 12 minutes or in fluorescent ultrafast format which takes only 7 minutes. We also show that His tag antigen purification can be performed on the fly while loading antigens to the Ni2+ magnetic beads in a process which takes only 12 min reducing the pre analytical time and cost. Finally, we show that the magnetic bead immunoassay is antigen flexible and can be performed using either Nucleocapsid, Spike or Spike RBD. The method performed with low inter and intra assay variability using different antigens and detection modes and was able to deliver >99.5% specificity and >95% sensitivity for a cohort of 203 pre pandemic and 63 COVID-19 positive samples.