Forbidden Zone Research Articles

Forbidden Protein Angles: Triosephosphate Isomerase as a Model for Studying Peripheral Residue Contribution to Catalysis.

Over the past 3.5 billion years of evolution, enzymes have adopted a seemingly infinite number of conformations to suit life on earth. However, torsional angles of proteins have settled into limited zones of energetically favorable dihedrals observed in Ramachandran plots. Areas outside said zones are believed to be forbidden to all amino acids, save glycine, due to steric hindrance. Triosephosphate Isomerase (TIM), a homodimer with a catalytic rate approaching the diffusion limit, contains an active site Lysine 13 (K13) with a dihedral within the forbidden zone (phi=69/psi=−139). Both the amino acid and the dihedral angle are conserved across all species of TIM and known crystal structures regardless of ligand. Only crystal structures of the engineered monomeric version (1MSS) show accepted β‐sheet dihedral values of phi=−135/psi=170 but experiments show a 1,000‐fold loss in activity. Based on these results, we hypothesized that adopting the forbidden torsion angle for K13 contributes to catalysis. Using a combination of computational and experimental approaches, four residues that interact with K13 (N11, M14, E97, and Q64) were mutated to alanine from single to quadruple mutants. In Silico Molecular Dynamic (MD) simulations of 5×200ns per mutant species were made using 2JK2 unliganded Human TIM as a starting structure. Heat Maps, containing 400,000 K13 dihedral values per run reveal full or partial loss of forbidden zone angles depending on mutant combination. Initial experimental results with E97A single mutant showed a three‐fold decrease in kcat with little change in the KM value suggesting a modest catalytic role for this residue. For this mutant the heatmaps revealed the K13 angle spends less than 30% of its time in the forbidden zone compared to over 50% occupation in the wildtype suggesting the rate decrease may be due to the mutation affecting the positioning of K13. In addition to ongoing In Vivo characterization of the remaining mutants, double mutant cycles will be used to evaluate their energetic connections with K13. As modern protein design relies on naturally occurring protein folds, understanding how to recreate forbidden angles may enhance catalytic rates in unnatural enzymes and achieve chemical reactions not yet envisioned by nature nor organic chemistry.Support or Funding InformationWe would like to thank California State University Long Beach and the Carl E. Riley Endowed STEM scholarship for their generous funding.Heat map of where K13 dihedral occupies space on Ramachandran Plot over 200ns of MD simulation using Wild Type Human Triosephosphate Isomerase (RCSB:2JK2).Figure 1

Effect of short-pulsed 200 keV C+ ion beam and continuous 350 keV He2+ ion beam irradiation on optical properties of Al-Si-N coatings with a various Si content

The article reports on the irradiation effects of 350 keV helium ions in the continuous mode and 200 keV carbon ions in the mode of short-pulsed implantation with doses of 20 MGy, 200 MGy and 600 MGy on the optical properties of crystalline aluminum nitride films and nanocomposite coatings based on Al-Si-N triple compound deposited by reactive magnetron sputtering onto a steel substrate. The energy and kinetic characteristics of the absorption spectra due to radiation defects and their simplest complexes are determined. Short-pulsed ion implantation is accompanied by intense radiation and thermal annealing of unstable radiation defects, along with their complexes and the formation of thermostable defect complexes. The influence of the interaction between the states of defects with the growth and/or radiation nature localized in the forbidden zone with the depth on the properties is established. Dose dependences of the optical characteristics indicate a high radiation resistance of the coatings. The radiation resistance of the coatings is due to the limiting effect of high concentration of growth defects on the accumulation of radiation defects, the wide band gap of nitrides, and the interaction of defects through the exchange of charge carriers between their levels.

Statistical Forbidden Zone Data Hiding Technique to Secure Various Data File

Video Steganography is a method where we can hide a wide range of documents with any extension into a carrying Video document. Right now exposition we are utilizing Forbidden Zone Data Hiding system where no adjustment is required in have signal range during information concealing procedure. Approach of this paper depends on the idea of message taking cover behind the video record that utilizations Forbidden Zone Data Hiding technique strategy. RA codes are utilizing with Forbidden zone information hiding to give robustness.

ELECTRON ENERGY SPECTRA IN QUANTIZED STRUCTURES

In this paper we study the Electron Energy Spectra (EES) in quantum wells (QWs) of heavily doped (HD) non-linear optical, III-V, II-VI, IV-VI and stressed Kane type compounds by formulating HDEES in each case respectively considering all the specialties of the energy band constants of the said materials. It is noted that the complex EES in many cases in HDS, instead of real one, occurs from the existence of the essential poles in the corresponding EES in the absence of band tails. The EES in QWs is Quantized 2D closed surfaces. As a collateral study we have also investigated the effective mass (EM), Density-of-states (DOS) function and the electron statistics in this context for the purpose of comprehensive understanding. The EM exists in the forbidden zone, which is impossible without the effect of band tailing. In the absence of band tails, the EM in the band gap of semiconductors is infinity. Besides, depending on the type of unperturbed carrier energy spectrum, the new forbidden zone will appear within the normal energy band gap for HDS. Under certain limiting conditions all the results for all the models get simplified the well-known results of an isotropic parabolic energy bands which exhibit the mathematical compatibility of our present generalized analysis.

Time-optimal trajectories for a trolley-like system with state constraint

We consider a time-optimal problem for trolley-like system (matherial point with inertia) passage from start to zero position (i.e. origin) under bounded control (acceleration) and linear state constraint. We solve it with Pontryagin maximum principle for state-constrained problems usage. We construct optimal trajectories synthesis and show that it is not simple “cut” of classical trolleyplike problem synthesis. State constraint generates “forbidden zone” bounded by state constraint boundary and half of parabola. We also shows that optimal trajectory (for selected range of state constraint line coefficient) has no more than three switching points (for the classical case, there is no more than one switching point). We analyse synthesis for different cases of parameters and demonstrates its evolution.

Optimal Offering Strategy of a Price-Maker Hydro Producer Considering the Effects of Crossing the Forbidden Zones

The phenomenon of crossing the forbidden zone is unavoidable and wasteful when scheduling the hydro units. In this paper, the effect of crossing the forbidden zone is taken into account using the strategic offering model to help the price-maker hydro producers (PMHPs) devise more economic offering strategies in this paper. This effect is economically quantified and formulated in the form of the mixed integer linear program (MILP) with the use of the big M method and the piecewise linear technique. Therefore, the effect of crossing the forbidden zone therefore can easily be incorporated into the strategic offering model. Based on the residual demand curve (RDC) scenarios, the strategic offering model, which consists of offering and self-scheduling models, is established according to the real-world data from the Three Gorges Project (TGP). The whole optimization model is then converted into the form of MILP formulations by properly discretizing the net head. A test case based on the TGP is presented, in which the strategic offering model is set as a comparable test while ignoring the effect of crossing the forbidden zone. The results provide insight on the offering strategy and physical system operations during a single day. The outcomes indicate that the model that incorporates the effect of crossing the forbidden zone will effectively prevent the crossing phenomenon from happening and that the proposed strategic offering model is more useful for assisting a PMHP in developing profitable offering strategy.

Фотолюминесценция квантовых точек Zn-=SUB=-1-x-y-=/SUB=-Cu-=SUB=-x-=/SUB=-Eu-=SUB=-y-=/SUB=-S/EuL-=SUB=-3-=/SUB=- в полиакрилатной матрице

Zinc sulfide is one of the most popular luminescent semiconductors of group A(II)B(VI). Doping ZnS quantum dots with Ln3+ ions makes it possible to form nanoscale structures in a semiconductor matrix containing isolated centers of narrow-band luminescence. The introduction of quantum dots into the acrylate matrix further stabilizes the particles and allows them to form their morphology. Nanoscale structures of Zn1-x-yCuxEuyS/EuL3, where L − trifluoroacetate are anions, were synthesized by the method of emerging reagents in situ in the medium of methyl methacrylate (MMA). ZnS doping was performed by simultaneous introduction of soluble precursors of zinc sulfide, as well as copper and europium trifluoroacetates into the acrylate reaction mixture. Polymer optically transparent compositions of PMMA/Zn1-x-yCuxEuyS/EuL3 were obtained by radical polymerization of MMA in the block. The excitation of luminescence of compositions is associated with Interzone electron transitions in ZnS, with a system of levels that form alloying ions in the forbidden zone of ZnS, as well as with their own energy absorption by Eu3+ ions. Broadband luminescence of compositions is caused by intracrystalline defects formed in ZnS during doping. Narrow-band luminescence occurs as a result OF 5D0→7Fj electronic transitions in Eu3+ ions associated with quantum dots, as well as being in the polymer matrix independently of them. The transfer of energy from the donor levels of the semiconductor matrix to the levels of Eu3+ ions, followed by its release in the form of luminescence, was confirmed by the imposition of absorption bands doped with ZnS and excitation bands of luminescence compositions, as well as an increase in the intensity of narrow-band luminescence of Eu3+ ions while reducing the intensity of a wide band of recombination luminescence of doped ZnS. A decrease in the intensity of the ZnS recombination luminescence band with an increase in the concentration of Eu3+ >1.0∙10-3 mol/L ions is also associated with the formation of a layer of complex europium compounds on the particle surface that prevent the passage of exciting radiation to the particle core.

An Effective Statistics Approach to Secure Data File through Forbidden Zone Data Hiding Technique

Video Steganography is a strategy wherein we can conceal a wide range of documents with any extension into a carrying Video document. Right now, are utilizing two fundamental wording that is have host file and carrier file where host file is a hidden file (any sort of record like content document, picture document, and sound/video document) and carrier file must be a video record. The primary inspiration of this paper is to make sure about moving of information by utilizing steganography and cryptography system. It is worried about implanting data in a harmless spread media in a safe and hearty way. Right now expositions we are utilizing Forbidden Zone Data Hiding strategy where no modification is required in have signal range during information hidden procedure. To safely moving the information record, we use video information covering up and utilizing revision limit of rehash gather code with predominance of taboo zone information stowing away. Utilizing this methodology we can likewise stow away and move the enormous video record whose size is bigger than spread record in secure way. The principle favorable position of utilizing video record sequestered from everything data is the additional protection from of the outsider or unintended beneficiary because of the overall multifaceted nature of video contrasted with picture and sound document. I have effectively actualized the proposed system of video information hiding utilizing forbidden zone datahiding strategy (FZDH) on content document, picture record, sound record and video document. The exceptional element is that we can hide the bigger size video record behind the smaller size cover record.

Temperature Dependence of the Density of States and the Change in the Band Gap in Semiconductors

The temperature dependence of the density of energy states in semiconductors has been studied. Strong doping with impurities with deep levels broadens the conduction band and the valence band. This enhances the absorption of light below the red border. Consequently, a possible change in the width of the forbidden zone. In this paper, using the mathematical model, temperature dependence of the density spectrum of states, changes in the band gap are shown by analyzing the density spectrum of energy states, an explanation of the anomalous temperature dependence in acceleration semiconductors is proposed, the effects of doping with a high concentration on the band gap of the semiconductor are investigated. Explained absorption in the range of 0.6-0.9 eV for silicon.

Water, a Green Solvent for Fabrication of High-Quality CsPbBr3 Films for Efficient Solar Cells.

Water has been labeled as a devil in fabrication and stability of perovskite solar cells. The inherent cognition impels researchers to prepare perovskite films in water-controlled conditions. Herein, water is used as a green solvent to prepare CsPbBr3 films through a two-step spin-coating method. Due to the high solubility of CsBr but low solubility of PbBr2 in water, it provides a possibility to deposit CsBr onto PbBr2 from water solution without destroying the film. Here, high-quality CsPbBr3 films are fabricated by spin-coating concentrated CsBr/H2O solution onto the PbBr2 film followed by annealing. As a result, the solar cells basing on a configuration of FTO/TiO2/CsPbBr3/Carbon exhibit a power conversion efficiency of 6.12%. This work provides a simple and easy way to prepare high-quality CsPbBr3 films for efficient solar cells. It makes a solid step toward reducing the solvent toxicity in the fabrication process of perovskite solar cells. It also breaks the forbidden zone for fabricating perovskite films from water and updates the inherent understanding of water in the research study of perovskite solar cells.

Nonlinear high-amplitude excitations of the CuPt7 crystal lattice: a molecular dynamics study

This article analyzes the structure and properties of the CuPt7 crystal for the possible existence of non-linear high-amplitude oscillations of the light alloy component. The densities of the phonon states of a crystal are calculated and analyzed for its different structures. It is demonstrated that the phonon system of a crystal has a narrow forbidden zone. The dependences of the possibility of the existence of high-amplitude oscillations on the initial conditions are revealed. It is shown that such oscillations are possible with the initial deviation of the Cu atom from the equilibrium position by more than 0.95 Å for FCC CuPt7. For such oscillators, their lifetime, the amount of stored energy, and other characteristics were obtained, which make it possible to characterize nonlinear high-amplitude lattice vibrations.

The Tsiolkovskiy crater landslide, the moon: An LROC view

Evidence suggests that the lobate flow feature that extends ~72 km outward from the western rim of Tsiolkovskiy crater is a long runout landslide. This landslide exhibits three (possibly four) morphologically different parts, likely caused by local conditions. All of these, plus the ejecta of Tsiolkovskiy crater, and its mare fill are approximately of the same crater model age, i.e., ~3.55 ± 0.1 Ga. The enormous size of this landslide is unique on the Moon and is a result of a combination of several geometric factors (e.g., its location relative to Fermi crater), and that Tsiolkovskiy crater was an oblique impact that produced an ejecta forbidden zone on its western side (Schultz, 1976). The landslide formed in this ejecta free zone as the rim of Tsiolkovskiy collapsed and its debris flowed across the relatively smooth, flat floor of Fermi crater. In this location, it could be easily identified as a landslide and not ejecta. Its mobility and coefficient of friction are similar to landslides in Valles Marineris on Mars, but less than wet or even dry terrestrial natural flows. This suggests that the Mars landslides may have been emplaced dry. The high density of small craters on the landslide is likely an illusion caused by the effects of age related differences in regolith thickness on crater morphology, and the presence of the abundant young, circular secondary craters produce by debris ejected from distant fresh craters.

Nonlinear isotropic elastic reduced and full Cosserat media: waves and instabilities

We consider two types of the nonlinear elastic Cosserat media: a full one, in which the strain energy depends both on the Cosserat deformation tensor and wryness tensor, and the reduced one, in which the strain energy depends only on the Cosserat deformation tensor, thus excluding its dependence on the gradient of micro-rotation. For these media, we obtain the equations for small deviations for an arbitrary nonlinear equilibrium and any type of elastic energy, which can be expanded into the Taylor series near this equilibrium. Then we consider an isotropic material under isotropic tension or compression and show that the equations for small deviations coincide with the equations of motion for the corresponding linear elastic continuum. For a wide class of materials with convex energy, strong compression leads to the instability of the medium caused by shear perturbations, and strong tension—to the instability with respect to shear–rotational perturbations. The last mechanism of instability is absent in the classical elastic continuum. For the reduced medium in the stable domain, shear–rotational wave has a forbidden band of frequencies, demonstrates strong dispersion near this zone, and there is a resonant frequency corresponding to the independent rotational oscillations. Characteristic frequencies depend on the stress state. Thus, it is a single negative acoustic metamaterial with a tunable band gap, depending on the nonlinear stress state, with respect to the shear waves. In the forbidden zone, localization phenomena near heterogeneities are present.

Method of defining region of allowed configurations in multidimensional space of generalized coordinates using hypercube graph

The work is devoted to the development of a knowledge base on possible positions of an android arm mechanism with allowance for the position of the previously known forbidden zone. The knowledge base is used for intelligent control of the arm movement of an android robot that functions autonomously in an organized space without human-operator assistance. The specified knowledge base is determined by the region of allowed configurations in the multidimensional space of generalized coordinates. Based on the methods of geometrical modeling, a representation method of the allowable configuration region with the use of hypercube graph is proposed.

On Internal Waves Propagating across a Geostrophic Front

AbstractReflection and transmission of normally incident internal waves propagating across a geostrophic front, like the Kuroshio or Gulf Stream, are investigated using a modified linear internal wave equation. A transformation from depth to buoyancy coordinates converts the equation to a canonical partial differential equation, sharing properties with conventional internal wave theory in the absence of a front. The equation type is determined by a parameter Δ, which is a function of horizontal and vertical gradients of buoyancy, the intrinsic frequency of the wave, and the effective inertial frequency, which incorporates the horizontal shear of background geostrophic flow. In the Northern Hemisphere, positive vorticity of the front may produce Δ ≤ 0, that is, a “forbidden zone,” in which wave solutions are not permitted. Thus, Δ = 0 is a virtual boundary that causes wave reflection and refraction, although waves may tunnel through forbidden zones that are weak or narrow. The slope of the surface and bottom boundaries in buoyancy coordinates (or the slope of the virtual boundary if a forbidden zone is present) determine wave reflection and transmission. The reflection coefficient for normally incident internal waves depends on rotation, isopycnal slope, topographic slope, and incident mode number. The scattering rate to high vertical modes allows a bulk estimate of the mixing rate, although the impact of internal wave-driven mixing on the geostrophic front is neglected.

First-principles investigations on the visible light photocatalytic activity of NaNbO3 by N and F doping

To enhance the photocatalytic activity of NaNbO3 (NNO) for hydrogen production through water splitting, monodoping with N or F atoms and codoping with (N, F) atom pairs are applied to modulate the electronic structures of NNO, which are calculated with hybrid functional HSE06 in VASP code. F doping into NNO crystals yields little band gap reduction of the system. Although N doping can significantly reduce band gap and enhance the visible light response of the system, presence of the localized unoccupied states above Fermi level in forbidden zone may promote the electron–hole recombination and possibly result in a poor photoconversion efficiency. A favorable improvement is achieved with N and F codoping, which yields not only an uncontaminated forbidden band but also the significantly narrowed band gap suitable for visible light absorption. Moreover, the band edge positions of various codoped systems are also suitable for the overall water splitting. The calculated formation energy indicates that N doping becomes more feasible in the presence of F due to charge balance. So, the (N, F) pairs codoping can be justified for improving the visible light driven photoactivity of NNO. The effects of concentration and separation of dopants on the photocatalytic performances are also investigated.

Investigation of defects in semiconductor structures based on AlInGaN solid solutions

Structures based on AlInGaN solid solutions were studied. The types of defects in them and the corresponding emission bands of photoluminescence (PL) spectra were identified. It is possible to determine the concentration of defects in the structure from the ratio of the intensities of the emission line, corresponding to the width of the forbidden zone in GaN, and the emission lines associated with defects.

A mathematical model of optical bistability and the multiplicity of its solutions

Abstract The problem of high-intensity laser pulse interaction with a semiconductor under the condition of the light energy nonlinear absorption is considered. Mathematical model of an optical bistability based on re-normalization of forbidden energy zone of a semiconductor because of the induced electric field is presented. The multiplicity of the problem solutions at the Neumann boundary conditions statement is discussed and ways of its overcoming are proposed. The effective method for the numerical solution of the problem is developed and computer simulation results are presented.

Optimization of critical speed of double spools with reverse rotation

Under the requirement of high speed, high pressure ratio and high thrust weight ratio, more and more aircraft engines adopt counter rotating technology. In this model, the F135 engine is used to research the dynamic characteristics of a dual rotor system with four supports supported by an intermediary. In this paper, the critical speed of the system is solved by the direct method. Compared with the Campell diagram, the eigenvalue problem of the required solution is greatly reduced. The critical speed is optimized by using genetic algorithm. Moreover, when the constraint of frequency forbidden zone is more severe, the elitist preserving genetic algorithm is used, which greatly reduces the required convergence algebra.

Spatial Suitability Evaluation of an Arid City Based on the Perspective of Major Function Oriented Zoning: A Case Study of Urumqi City in Xinjiang, China

The realization of regional sustainable development has been a popular research topic during the process of urbanization. To explore the coordination relationships between urban development and ecological security—taking Urumqi city, a representative arid city in Xinjiang, China, as a study area—this study has constructed a framework of spatial suitability evaluation based on the characteristics of a Mountain–Oasis–Desert System (MODS) in an arid area under the framework of major function oriented zoning (MFOZ). A spatial overlay analysis using Geographic Information System (GIS) with a 5 m × 5 m grid or towns and streets as the basic unit was applied to comprehensively evaluate spatial suitability. The results showed that the study area was zoned into a forbidden development zone (as patches set in towns and streets), an ecological protection zone (nine towns or streets), a moderate development zone (16 towns or streets), and a key development zone (82 towns or streets), accounting for 30.35%, 32.50%, 23.79%, and 13.36%, respectively. The zoning results provided a basis to pointedly put forward the development and protection strategies of each administrative unit; and the research framework can be applied to other arid areas for the decision-making related to the urban space layout and environmental management.