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Essential oil from Artemisia herba alba (Art) was hydrodistilled and tested as corrosion inhibitor of steel in 0.5 M H₂SO₄ using weight loss measurements and electrochemical polarization methods. Results gathered show that this natural oil reduced the corrosion rate by the cathodic action. Its inhibition efficiency attains the maximum (74%) at 1 g/L. The inhibition efficiency of Arm oil increases with the rise of temperature. The adsorption isotherm of natural product on the steel has been determined. A. herba alba essential oil was obtained by hydrodistillation and its chemical composition oil was investigated by capillary GC and GC/MS. The major components were chrysanthenone (30.6%) and camphor (24.4%).

To enable an accurate recognition of neuronal excitability in an epileptic brain for modeling or localization of epileptic zone, here the brain response to single-pulse electrical stimulation (SPES) has been decomposed into its constituent components using adaptive singular spectrum analysis (SSA). Given the response at neuronal level, these components are expected to be the inhibitory and excitatory components. The prime objective is to thoroughly investigate the nature of delayed responses (elicited between 100ms–1 s after SPES) for localization of the epileptic zone. SSA is a powerful subspace signal analysis method for separation of single channel signals into their constituent uncorrelated components. The consistency in the results for both early and delayed brain responses verifies the usability of the approach.

Seizure activity leads to increases in extracellular potassium concentration ([K${}^{+}$]o), which can result in changes in neuronal passive and active membrane properties as well as in population activities. In this study, we examined how extracellular potassium modulates seizure activities using an acute 4-AP induced seizure model in the neocortex, both in vivo and in vitro. Moderately elevated [K${}^{+}$]o up to 9mM prolonged seizure durations and shortened interictal intervals as well as depolarized the neuronal resting membrane potential (RMP). However, when [K${}^{+}$]o reached higher than 9mM, seizure like events (SLEs) were blocked and neurons went into a depolarization-blocked state. Spreading depression was never observed as the blockade of ictal events could be reversed within 1–2min after the raised [K${}^{+}$]o was changed back to control levels. This concentration-dependent dual effect of [K${}^{+}$]o was observed using in vivo and in vitro mouse brain preparations as well as in human neocortical tissue resected during epilepsy surgery. Blocking the Ih current, mediated by hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, modulated the elevated [K${}^{+}$]o influence on SLEs by promoting the high [K${}^{+}$]o inhibitory actions. These results demonstrate biphasic actions of raised [K${}^{+}$]o on neuronal excitability and seizure activity.

The inhibition effect of synthesized N′-(phenylmethylidene)-2-(2-methyl-1H-benzimidazol-1-yl)acetohydrazides, N′-(4-methylphenylmethylidene)-2-(2-methyl-1H-benzimidazol-1-yl)acetohydrazides, and N′-(4-methoxyphenylmethylidene)-2-(2-methyl-1H-benzimidazol-1-yl)acetohydrazides on the corrosion behaviour of N80 steel in 15% hydrochloric acid solution was investigated using weight loss, potentiostatic polarization and electrochemical impedance spectroscopy methods. The inhibition efficiency increased as the concentration of the inhibitors was increased. The effect of temperature on corrosion inhibition was investigated by weight loss method and thermodynamic parameters were calculated. Potentiodynamic polarization measurements show that all the three studied inhibitors act as mixed inhibitor. The adsorption of inhibitors on N80 steel surface obeys Langmuir adsorption isotherm. The structure of inhibitors was optimized using semiemperical AM1 method. Theoretical parameters such as the highest occupied molecular orbital (E_HOMO), lowest unoccupied molecular orbital (E_LUMO) energy levels, energy gap (ΔE = E_LUMO - E_HOMO), dipole moment (μ), global hardness (γ), softness (σ), binding energy, molecular surface area and the fraction of electrons transferred (ΔN) were calculated and the adsorption mechanism was discussed. Scanning electron microscopy was used to characterize the surface marphology of the N80 steel.

This article argues that conscious attention exists not so much for selecting an immediate action as for using the current task to focus specialized learning for the action-selection mechanism(s) and predictive models on tasks and environmental contingencies likely to affect the conscious agent. It is perfectly possible to build this sort of a system into machine intelligence, but it would not be strictly necessary unless the intelligence needs to learn and is resource-bounded with respect to the rate of learning versus the rate of relevant environmental change. Support for this theory is drawn from scientific research and AI simulations. Consequences are discussed with respect to self-consciousness and ethical obligations to and for AI.

We study the synchronization of bursting cells that are coupled through both excitatory and inhibitory connections. We extend our recent results on networks of Hindmarsh–Rose bursting neurons [Belykh et al., 2014] to coupled Sherman β-cell models and show that the addition of repulsive inhibition to an excitatory network can induce synchronization. We discuss the mechanism of this purely synergenic phenomenon and demonstrate that the inhibition leads to the disappearance of a homoclinic bifurcation that governs the type of synchronized bursting. As a result, the inhibition causes the transition from square-wave to easier-to-synchronize plateau bursting, so that weaker excitation is sufficient to induce bursting synchrony. We dedicate this paper to the memory of Leonid P. Shilnikov, the pioneer of homoclinic bifurcation theory, and emphasize the importance of homoclinic bifurcations for understanding the emergence of synchronized rhythms in bursting networks.

Recently, upregulation of metabotropic glutamate receptors (mGluRs) on hippocampal astrocytes in epileptic tissues has become part of the etiology of epilepsy and suggests the involvement of astrocytes in the disease. Through computational modeling, we have shown in previous work that upregulated mGluRs on astrocytes can give rise to positive feedback in closed loop neuron-astrocyte circuits with epilepsy-type spontaneous neuronal spiking. In this paper we further quantify the necessary degree of upregulation of astrocytic mGluRs, relate it to recent clinical and experimental studies, and address through computational modeling the role of synaptic inhibition through interneurons in this form of hyperexcitability. We conclude that inhibitive circuitry cannot tame this form of hyperexcitability.

Much research has shown that phyllotactic patterns can be considered as resulting from a growth process. A simple inhibition mechanism is used to generate automatically the spiral patterns and the magic Fibonacci numbers. We constrain the mechanism by introducing the requirement of the threshold energy-rate in producing primordia. With this modification, we are able to generate not only spiral but also whorled patterns. Our model can yield various possibilities of the whorled patterns observed in plants.

Dodecylamine spontaneously adsorbs on carbon steel via its polar group (-NH₂) in hydrochloric acid solution. Furthermore, it forms a monolayer film on carbon steel surface. The inhibition mechanism of dodecylamine for carbon steel is geometric blocking effect. The adsorption of dodecylamine on carbon steel surface follows Arrhenius equation. The adsorption slightly increases activated energy, but greatly reduces pre-exponential factor value. Atomic force microscopy force curves indicate that at the area without adsorbed dodecylamine, no obvious adhere force occurs. At the area with adsorbed dodecylamine, however, an average 1.3 nN adhere force is observed.

Two experiments are reported in which participants perceived different physical quantities: size and speed. The perceptual tasks were performed in the context of motor performance problems. Participants perceived the size of objects in order to grasp the objects single handed or with both hands. Likewise, participants perceived the speed of a moving treadmill in order to control walking or running at that speed. In both experiments, the perceptual tasks were repeatedly performed by the participants while the to-be-perceived quantity was gradually varied from small to large objects (Experiment 1) and from low to high speeds (Experiment 2). Hysteresis with negative sign was found when participants were not allowed to execute the motor component, that is, when the execution stage was decoupled from the planning stage. No such effect was found in the control condition, when participants were allowed to execute the motor action. Using a Lotka–Volterra–Haken model for two competing neural populations, it is argued that the observations are consistent with the notion that the repetitions induce an adaptation effect of the perceptual system via top-down regulation. Moreover, the amount of synaptic modulation involved in the adaptation is estimated from participant data.

Rationale: Benzylpiperazine (BZP) has been found to increase neural activation in the dorsal striatum when compared to placebo in response to a Stroop paradigm, in addition, subjective effects have been compared to dexamphetamine (DEX). Despite their similarities, the two have not been directly compared in respect to their effects on selective attention and inhibition. Objectives: To use a double-blind placebo-controlled crossover study to compare the acute effects of BZP and DEX on executive function using functional magnetic resonance imaging (fMRI) and an event-related Stroop task. Methods: Eleven healthy participants aged 18–40 years undertook the Stroop task 90min after taking an oral dose of either BZP (200mg), DEX (20mg) or placebo. Results: BZP induced a greater increase in activation than DEX in the inferior frontal gyrus (IFG) during the Stroop task. DEX increased BOLD signal in the thalamus and decreased it in the IFG in comparison to placebo. Conclusion: Despite BZP and DEX reportedly inducing similar subjective effects, there are different patterns of neural activation. We believe this differential activity is due to pharmacological differences in their receptor binding profiles and that subsequent inhibitory effects might be due to their direct effect on dopaminergic activity.

In the present work, using the interaction of tetra-(4-sulfophenyl)porphyrin with copper(II) chloride as an example, it has been shown how different amino acid additives (glycine, valine, leucine and tryptophan) catalyze or inhibit the formation of Cu-porphyrin as a function of the chemical environment (borate buffer (pH7.4), DMSO) and the concentration of the additive. It has been demonstrated that the type of amino acid affects the complexation reaction rate. Possible mechanisms of metalloporphyrin formation and the ways of their acceleration are discussed.

As multifunctional catalytic hemoglobins, dehaloperoxidase isoenzymes A and B (DHP A and B) are among the most versatile hemoproteins in terms of activities displayed. The ability of DHP to bind over twenty different substrates in the distal pocket might appear to resemble the promiscuousness of monooxygenase enzymes, yet there are identifiable substrate-specific interactions that can steer the type of oxidation (O-atom vs. electron transfer) that occurs inside the DHP distal pocket. Here, we have investigated the DHP A(V59W) mutant in order to probe the limits of conformational flexibility in the distal pocket as it relates to the genesis of this substrate-dependent activity differentiation. The X-ray crystal structure of the metaquo DHP A(V59W) mutant (PDB 3K3U) and the V59W mutant in complex with fluoride [denoted as DHP A(V59W-F)] (PDB 7MNH) show significant mobility of the tryptophan in the distal pocket, with two parallel conformations having W59-N${}^{𝜀1}$ H-bonded to a heme-bound ligand (H₂O or F${}^{-})$, and another conformation [observed only in DHP A(V59W-F)] that brings W59 sufficiently close to the heme as to preclude axial ligand binding. UV-vis and resonance Raman spectroscopic studies show that DHP A(V59W) is 5-coordinate high spin (5cHS) at pH 5 and 6-coordinate high spin (6cHS) at pH 7, whereas DHP A(V59W-F) is 6cHS from pH 5 to 7. Enzyme assays confirm robust peroxidase activity at pH 5, but complete loss of activity at pH 7. We find no evidence that tryptophan plays a role in the oxidation mechanism ($i.e$. radical formation). Instead, the data reveal a new mechanism of DHP inhibition, namely a shift towards a non-reactive form by OH${}^{-}$ ligation to the heme-Fe that is strongly stabilized (presumably through H-bonding interactions) by the presence of W59 in the distal cavity.

Bioleaching is the dissolution of metal sulfides like pyrite by bacterial oxidation processes. Beside desired heap or tank leaching for winning metals such as copper or gold, unwanted bioleaching causes acid mine drainage (AMD)/acid rock drainage (ARD) e.g. in during coal mining processes. Bioleaching can cause acidification of surface- and groundwater concomitant with pollution by high amounts of heavy metals. The addition of a surfactant to active leaching cultures decreases bacterial cell numbers and leaching. To investigate the inhibition effect of the surfactant in situ, a percolator system was used. Percolators were filled with pyrite containing material from a brown coal area where unwanted bacterial leaching occurs. The surfactant was added after bacterial leaching was established. The addition of the surfactant inhibited leaching within one week till the end of the experiment after 13 weeks. Based on these findings, applications for the inhibition of bacterial leaching in brown coal mining areas can be established.