scholarly journals Reductive Stress of Sulfur-Containing Amino Acids within Proteins and Implication of Tandem Protein–Lipid Damage

2021 ◽  
Vol 22 (23) ◽  
pp. 12863
Author(s):  
Chryssostomos Chatgilialoglu ◽  
Carla Ferreri
Keyword(s):  
The Other ◽  
Aminobutyric Acid ◽  
Chemical Transformations ◽  
Hydrogen Atoms ◽  
Unsaturated Lipids ◽  
Hydrated Electrons ◽  
Chemistry Modeling ◽  
Lipid Damages ◽  
The Stability ◽  
Sulfur Containing

Reductive radical stress represents the other side of the redox spectrum, less studied but equally important compared to oxidative stress. The reactivity of hydrogen atoms (H•) and hydrated electrons (e–aq) connected with peptides/proteins is summarized, focusing on the chemical transformations of methionine (Met) and cystine (CysS–SCys) residues into α-aminobutyric acid and alanine, respectively. Chemical and mechanistic aspects of desulfurization processes with formation of diffusible sulfur-centered radicals, such as methanethiyl (CH3S•) and sulfhydryl (HS•) radicals, are discussed. These findings are further applied to biomimetic radical chemistry, modeling the occurrence of tandem protein–lipid damages in proteo-liposomes and demonstrating that generation of sulfur-centered radicals from a variety of proteins is coupled with the cis–trans isomerization of unsaturated lipids in membranes. Recent applications to pharmaceutical and pharmacological contexts are described, evidencing novel perspectives in the stability of formulations and mode of action of drugs, respectively.

Uniformity of Magnification from Different Electron Microscopes

1967 ◽  
Vol 25 ◽  
pp. 32-33
Author(s):  
Godfrey C. Hoskins ◽  
V. Williams ◽  
V. Allison
Keyword(s):  
Diffraction Grating ◽  
The Other ◽  
Carbon Replica ◽  
Electron Microscopes ◽  
The Stability

The method demonstrated is an adaptation of a proven procedure for accurately determining the magnification of light photomicrographs. Because of the stability of modern electrical lenses, the method is shown to be directly applicable for providing precise reproducibility of magnification in various models of electron microscopes.A readily recognizable area of a carbon replica of a crossed-line diffraction grating is used as a standard. The same area of the standard was photographed in Phillips EM 200, Hitachi HU-11B2, and RCA EMU 3F electron microscopes at taps representative of the range of magnification of each. Negatives from one microscope were selected as guides and printed at convenient magnifications; then negatives from each of the other microscopes were projected to register with these prints. By deferring measurement to the print rather than comparing negatives, correspondence of magnification of the specimen in the three microscopes could be brought to within 2%.

scholarly journals Black Hole Algorithm for Sustainable Design of Counterfort Retaining Walls

2020 ◽  
Vol 12 (7) ◽  
pp. 2767 ◽  
Author(s):  
Víctor Yepes ◽  
José V. Martí ◽  
José García
Keyword(s):  
Black Hole ◽  
Sustainable Design ◽  
Retaining Walls ◽  
The Other ◽  
Trade Off ◽  
Construction Company ◽  
Geometric Variables ◽  
The Stability ◽  
The Cost ◽  
Black Hole Algorithm

The optimization of the cost and CO 2 emissions in earth-retaining walls is of relevance, since these structures are often used in civil engineering. The optimization of costs is essential for the competitiveness of the construction company, and the optimization of emissions is relevant in the environmental impact of construction. To address the optimization, black hole metaheuristics were used, along with a discretization mechanism based on min–max normalization. The stability of the algorithm was evaluated with respect to the solutions obtained; the steel and concrete values obtained in both optimizations were analyzed. Additionally, the geometric variables of the structure were compared. Finally, the results obtained were compared with another algorithm that solved the problem. The results show that there is a trade-off between the use of steel and concrete. The solutions that minimize CO 2 emissions prefer the use of concrete instead of those that optimize the cost. On the other hand, when comparing the geometric variables, it is seen that most remain similar in both optimizations except for the distance between buttresses. When comparing with another algorithm, the results show a good performance in optimization using the black hole algorithm.

scholarly journals A Fractional SAIDR Model in the Frame of Atangana–Baleanu Derivative

2021 ◽  
Vol 5 (2) ◽  
pp. 32
Author(s):  
Esmehan Uçar ◽  
Sümeyra Uçar ◽  
Fırat Evirgen ◽  
Necati Özdemir
Keyword(s):  
Existence And Uniqueness ◽  
Laplace Transformation ◽  
Cell Phones ◽  
Mobile Network ◽  
The Other ◽  
Banach Fixed Point Theorem ◽  
Propagation Models ◽  
Computer Worms ◽  
Computer Viruses ◽  
The Stability

It is possible to produce mobile phone worms, which are computer viruses with the ability to command the running of cell phones by taking advantage of their flaws, to be transmitted from one device to the other with increasing numbers. In our day, one of the services to gain currency for circulating these malignant worms is SMS. The distinctions of computers from mobile devices render the existing propagation models of computer worms unable to start operating instantaneously in the mobile network, and this is particularly valid for the SMS framework. The susceptible–affected–infectious–suspended–recovered model with a classical derivative (abbreviated as SAIDR) was coined by Xiao et al., (2017) in order to correctly estimate the spread of worms by means of SMS. This study is the first to implement an Atangana–Baleanu (AB) derivative in association with the fractional SAIDR model, depending upon the SAIDR model. The existence and uniqueness of the drinking model solutions together with the stability analysis are shown through the Banach fixed point theorem. The special solution of the model is investigated using the Laplace transformation and then we present a set of numeric graphics by varying the fractional-order θ with the intention of showing the effectiveness of the fractional derivative.

scholarly journals Competing Conventions with Costly Information Acquisition

Games ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 53
Author(s):  
Roberto Rozzi
Keyword(s):  
Information Acquisition ◽  
Evolutionary Model ◽  
Equilibrium Selection ◽  
The Other ◽  
Group Interactions ◽  
Social Coordination ◽  
Long Run ◽  
Stochastic Stability Analysis ◽  
The Stability ◽  
The Cost

We consider an evolutionary model of social coordination in a 2 × 2 game where two groups of players prefer to coordinate on different actions. Players can pay a cost to learn their opponent’s group: if they pay it, they can condition their actions concerning the groups. We assess the stability of outcomes in the long run using stochastic stability analysis. We find that three elements matter for the equilibrium selection: the group size, the strength of preferences, and the information’s cost. If the cost is too high, players never learn the group of their opponents in the long run. If one group is stronger in preferences for its favorite action than the other, or its size is sufficiently large compared to the other group, every player plays that group’s favorite action. If both groups are strong enough in preferences, or if none of the groups’ sizes is large enough, players play their favorite actions and miscoordinate in inter-group interactions. Lower levels of the cost favor coordination. Indeed, when the cost is low, in inside-group interactions, players always coordinate on their favorite action, while in inter-group interactions, they coordinate on the favorite action of the group that is stronger in preferences or large enough.

A Biomechanical Evaluation of Three Forms of Internal Fixation Used in Ankle Arthrodesis

1994 ◽  
Vol 15 (6) ◽  
pp. 297-300 ◽  
Author(s):  
Michael P. Dohm ◽  
James B. Benjamin ◽  
Jeffrey Harrison ◽  
John A. Szivek
Keyword(s):  
Internal Fixation ◽  
Plate Fixation ◽  
Ankle Arthrodesis ◽  
Biomechanical Study ◽  
The Other ◽  
Fixation Failure ◽  
Plate Group ◽  
Biomechanical Evaluation ◽  
The Stability ◽  
Fibular Strut

A biomechanical study was undertaken to evaluate the relative stability of three types of internal fixation used for ankle arthrodesis. Crossed screw fixation, RAF fibular strut fixation, and T-plate fixation were tested in 30 cadaver ankles using an MTS machine. T-plate fixation consistantly provided the stiffest construct when compared with the other types of fixation. Failure occurred by distraction of bony surfaces, posterior to the plane of fixation, in the crossed screw and RAF groups. In contrast, failure in the T-plate group occurred through compression of bone anterior to the midcoronal plane of the tibia. Although the stability of fixation is only one factor in determining the success or failure of ankle arthrodesis, the results of this study would support T-plate fixation over the other forms tested.

scholarly journals Tetracycline Induces Stabilization of mRNA in Bacillus subtilis

2002 ◽  
Vol 184 (4) ◽  
pp. 889-894 ◽  
Author(s):  
Yi Wei ◽  
David H. Bechhofer
Keyword(s):  
Bacillus Subtilis ◽  
Mrna Stability ◽  
The Other ◽  
Leader Region ◽  
Subinhibitory Concentration ◽  
Coding Sequence ◽  
Mrna Stabilization ◽  
Threefold Increase ◽  
The Stability

ABSTRACT The tet(L) gene of Bacillus subtilis confers low-level tetracycline (Tc) resistance. Previous work examining the >20-fold-inducible expression of tet(L) by Tc demonstrated a 12-fold translational induction. Here we show that the other component of tet(L) induction is at the level of mRNA stabilization. Addition of a subinhibitory concentration of Tc results in a two- to threefold increase in tet(L) mRNA stability. Using a plasmid-borne derivative of tet(L) with a large in-frame deletion of the coding sequence, the mechanism of Tc-induced stability was explored by measuring the decay of tet(L) mRNAs carrying specific mutations in the leader region. The results of these experiments, as well as experiments with a B. subtilis strain that is resistant to Tc due to a mutation in the ribosomal S10 protein, suggest different mechanisms for the effects of Tc on translation and on mRNA stability. The key role of the 5" end in determining mRNA stability was confirmed in these experiments. Surprisingly, the stability of several other B. subtilis mRNAs was also induced by Tc, which indicates that addition of Tc may result in a general stabilization of mRNA.

Two ubiquitin-like conjugation systems that mediate membrane formation during autophagy

2013 ◽  
Vol 55 ◽  
pp. 39-50 ◽  
Author(s):  
Hitoshi Nakatogawa
Keyword(s):  
Light Chain ◽  
Membrane Dynamics ◽  
The Other ◽  
Aminobutyric Acid ◽  
Amino Group ◽  
Autophagosome Formation ◽  
Acid Receptor ◽  
Receptor Associated Protein ◽  
Atg Proteins ◽  
C Terminus

In autophagy, the autophagosome, a transient organelle specialized for the sequestration and lysosomal or vacuolar transport of cellular constituents, is formed via unique membrane dynamics. This process requires concerted actions of a distinctive set of proteins named Atg (autophagy-related). Atg proteins include two ubiquitin-like proteins, Atg12 and Atg8 [LC3 (light-chain 3) and GABARAP (γ-aminobutyric acid receptor-associated protein) in mammals]. Sequential reactions by the E1 enzyme Atg7 and the E2 enzyme Atg10 conjugate Atg12 to the lysine residue in Atg5, and the resulting Atg12–Atg5 conjugate forms a complex with Atg16. On the other hand, Atg8 is first processed at the C-terminus by Atg4, which is related to ubiquitin-processing/deconjugating enzymes. Atg8 is then activated by Atg7 (shared with Atg12) and, via the E2 enzyme Atg3, finally conjugated to the amino group of the lipid PE (phosphatidylethanolamine). The Atg12–Atg5–Atg16 complex acts as an E3 enzyme for the conjugation reaction of Atg8; it enhances the E2 activity of Atg3 and specifies the site of Atg8–PE production to be autophagy-related membranes. Atg8–PE is suggested to be involved in autophagosome formation at multiple steps, including membrane expansion and closure. Moreover, Atg4 cleaves Atg8–PE to liberate Atg8 from membranes for reuse, and this reaction can also regulate autophagosome formation. Thus these two ubiquitin-like systems are intimately involved in driving the biogenesis of the autophagosomal membrane.

scholarly journals Bioinspired organometallic chemistry

2002 ◽  
Vol 74 (1) ◽  
pp. 115-122 ◽  
Author(s):  
Lanny S. Liebeskind ◽  
Jiri Srogl ◽  
Cecile Savarin ◽  
Concepcion Polanco
Keyword(s):  
Organometallic Chemistry ◽  
Refractory Metal ◽  
Redox Active ◽  
The Stability ◽  
New Procedures ◽  
Sulfur Containing ◽  
Insight Into

Given the stability of the bond between a mercaptide ligand and various redox-active metals, it is of interest that Nature has evolved significant metalloenzymatic processes that involve key interactions of sulfur-containing functionalities with metals such as Ni, Co, Cu, and Fe. From a chemical perspective, it is striking that these metals can function as robust biocatalysts in vivo, even though they are often "poisoned" as catalysts in vitro through formation of refractory metal thiolates. Insight into the nature of this chemical discrepancy is under study in order to open new procedures in synthetic organic and organometallic chemistry.

Existence of Periodic Solution for Equation of Motion of Simple Beams With Harmonically Variable Length

1995 ◽  
Author(s):  
Ebrahim Esmailzadeh ◽  
Gholamreza Nakhaie-Jazar ◽  
Bahman Mehri
Keyword(s):  
Periodic Solution ◽  
Fixed Point ◽  
Nonlinear Function ◽  
Axial Direction ◽  
Equation Of Motion ◽  
The Other ◽  
Sufficient Condition ◽  
Vibrating String ◽  
The Stability ◽  
Special Case

Abstract The transverse vibrating motion of a simple beam with one end fixed while driven harmonically along its axial direction from the other end is investigated. For a special case of zero value for the rigidity of the beam, the system reduces to that of a vibrating string with the corresponding equation of its motion. The sufficient condition for the periodic solution of the beam is then derived by means of the Green’s function and Schauder’s fixed point theorem. The criteria for the stability of the system is well defined and the condition for which the performance of the beam behaves as a nonlinear function is stated.

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