Mixture Of Different States Research Articles

The Multiple States of Environmental DNA and What Is Known about Their Persistence in Aquatic Environments.

Increased use of environmental DNA (eDNA) analysis for indirect species detection has spurred the need to understand eDNA persistence in the environment. Understanding the persistence of eDNA is complex because it exists in a mixture of different states (e.g., dissolved, particle adsorbed, intracellular, and intraorganellar), and each state is expected to have a specific decay rate that depends on environmental parameters. Thus, improving knowledge about eDNA conversion rates between states and the reactions that degrade eDNA in different states is needed. Here, we focus on eukaryotic extraorganismal eDNA, outline how water chemistry and suspended mineral particles likely affect conversion among each eDNA state, and indicate how environmental parameters affect persistence of states in the water column. On the basis of deducing these controlling parameters, we synthesized the eDNA literature to assess whether we could already derive a general understanding of eDNA states persisting in the environment. However, we found that these parameters are often not being measured or reported when measured, and in many cases very few experimental data exist from which to draw conclusions. Therefore, further study of how environmental parameters affect eDNA state conversion and eDNA decay in aquatic environments is needed. We recommend analytic controls that can be used during the processing of water to assess potential losses of different eDNA states if all were present in a water sample, and we outline future experimental work that would help determine the dominant eDNA states in water.

Investigation of the minimum ignition temperature and lower explosion limit of multi-components hybrid mixtures in the Godbert-Greenwald furnace

Abstract Explosion hazards involving mixtures of different states of aggregation continue to occur in facilities where dusts, gases or solvents are handled or processed. In order to prevent or mitigate the risk associated with these mixtures, more knowledge of the explosion behavior of hybrid mixtures is required. An experimental investigation of the minimum ignition temperature (MIT) and the lower explosion limit/minimum explosion concentration (LEL/MEC) of three component hybrid mixtures of combustible dusts, gases and vapors in air were performed in a modified Godbert-Greenwald (GG) furnace. The study comprised three dusts, two gases and two solvents vapors. For the dusts alone, the experimental protocol was in accordance with the European standard EN 50281-2-1, whereas for the gases, solvent vapors and mixtures of these with dusts, this protocol had to be modified slightly. It was found that the MITs of the gases and solvent vapors decreased significantly when a combustible dust at a concentration below the MEC of the dust alone, was added. A significant decrease in the MIT was also found if the gas/vapor atmosphere was mixed with a dispersed combustible dust that could not be ignited alone at the given temperature in the GG furnace. For example, the MIT of methane decrease from 600 °C to 585 °C when a small amount of starch was added. This hybrid MIT further decreased to 490 °C when a non-explosible third component, ethanol, was added. It was also found that a hybrid cloud of a combustible dust at a concentration less than the MEC and a combustible gas at a concentration less than the LEL could be ignited in the GG furnace. For example, the MEC of starch decreased from about 145 g/m3 to 40 g/m3 when methane at a concentration below the LEL was added. This explosible concentration of starch– methane mixture further decreased to 25 g/m3 when a small fraction of a third component, hexane, was added.

Structural study of the X-ray-induced enzymatic reduction of molecular oxygen to water by Steccherinum murashkinskyi laccase: insights into the reaction mechanism.

The laccase from Steccherinum murashkinskyi is a member of the large family of multicopper oxidases that catalyze the oxidation of a wide range of organic and inorganic substrates, accompanied by the reduction of dioxygen to water. The reducing properties of X-ray radiation and the high quality of the laccase crystals allow the study of the catalytic reduction of dioxygen to water directly in a crystal. A series of diffraction data sets with increasing absorbed radiation dose were collected from a single crystal of Steccherinum murashkinskyi laccase at 1.35 Å resolution. Changes in the active-site structure associated with the reduction of molecular oxygen to water on increasing the absorbed dose of ionizing radiation were detected. The structures in the series are mixtures of different states of the enzyme-substrate complex. Nevertheless, it was possible to interpret these structures as complexes of various oxygen ligands with copper ions in different oxidation states. The results allowed the mechanism of oxygen reduction catalyzed by laccases to be refined.

Molecular Characterization of a Purified 5-HT4 Receptor: A STRUCTURAL BASIS FOR DRUG EFFICACY

Serotonin 5-HT(4(a)) receptor, a G-protein-coupled receptor (GPCR), was produced as a functional isolated protein using Escherichia coli as an expression system. The isolated receptor was characterized at the molecular level by circular dichroism (CD) and steady-state fluorescence. A specific change in the near-UV CD band associated with the GPCR disulfide bond connecting the third transmembrane domain to the second extracellular loop (e2) was observed upon agonist binding to the purified receptor. This is a direct experimental evidence for a change in the conformation of the e2 loop upon receptor activation. Different variations were obtained depending whether the ligand was an agonist (partial or full) or an inverse agonist. In contrast, antagonist binding did not induce any variation. These observations provide a first direct evidence for the fact that free (or antagonist-occupied), active (partial- or full agonist-occupied) and silent (inverse agonist-occupied) states of the receptor involve different arrangements of the e2 loop. Finally, ligand-induced changes in the fluorescence emission profile of the purified receptor confirmed that the partial agonist stabilized a single, well-defined, conformational state and not a mixture of different states. This result is of particular interest in a pharmacological perspective since it directly demonstrates that the efficacy of a drug is likely due to the stabilization of a ligand-specific state rather than selection of a mixture of different conformational states of the receptor.

COLLECTIVE PROPERTIES OF UNCONVENTIONAL SUPERCONDUCTORS

In light of recent experiments, the study of the collective excitations in unconventional superconductors (USC) becomes very important. We build by path integration technique 2D and 3D models of p- and d-pairing for superfluids and superconductors (SC). Within these models we calculate the collective excitations in different USC (high temperature superconductors (HTSC), heavy fermion superconductors (HFSC) etc.) under p- and d-pairing. We considered both bulk and 2D systems. Some recent ideas concerning realization in HTSC of the mixtures of different states are investigated. In particular, we consider the mixture of dx2-y2 and dxy states in HTSC. Obtained results could be used for interpretation of the sound and microwave absorption data as well as for identification of the type of pairing and order parameter in unconventional superconductors.

Collective properties of superconductors with nontrivial pairing

Three-and two-dimensional models of p-and d-pairing are constructed for superconductors and superfluid quantum liquids using the functional integration formalism. In these models, the collective excitation spectra are calculated for superconductors with nontrivial pairing (such as high-temperature superconductors (HTSC) and heavy-fermion superconductors (HFSC)) for p-and d-pairing. Both three-and two-dimensional systems are considered. Some of recent ideas concerning the realization of the mixture of different states in HTSC are considered. In particular, the mixture of states \(d_{x^2 - y^2 } + id_{xy} \) is analyzed. The obtained results of calculations of collective excitation spectra in superconductors with nontrivial pairing may be used for determining the type of pairing and the order parameter in HTSC and HFSC and also for interpreting the experimental results on ultrasound and microwave absorption in these system.

Some consequences of the strengthened interpretative rules of quantum mechanics

In this paper some consequences of the strengthened interpretative rules of quantum mechanics, which were proposed in an earlier paper, are obtained. It is also seen that, in general, the usual interpretative rules are too weak to obtain these results. For example, it is proved from the strengthened rules that if f:R → R is a Borel function which is also τ-definable, then for each observable A the procedure ``measure A and compute f(A outcome)'' is an f(A) measurement procedure. It is also shown that there exist Borel f and observables A such that the above procedure is not an f(A) measurement procedure. Two methods of measuring the sum A + B of two observables are then considered: The measurement of A and B on different systems followed by addition of the results and (if A and B commute) the simultaneous measurement of A and B on the same system followed by addition. It is proved from the strengthened rules that the first method is not a valid measurement procedure and the second is valid. Besides these, other processes such as procedures for preparing mixtures of different states, and the empirical generation of probability measures from outcome sequences are considered.