NUMERICAL SIMULATION OF ECCENTRICITY CREATION IN THE PRODUCTION OF HOT ROLLED TUBES

The paper deals with the issue of eccentricity in the technological node of the piercing press, under selected conditions, which result from the possibilities of production in the conditions of ŽP a.s. These conditions were verified and adapted to the rolling process. This process consisting of individual technological nodes on the rolling mill, in which eccentricity is created on the piercing press and the following steps eliminate it in other technological nodes. For quality analysis of manufacturing tubes using numerical simulation, it is necessary to know the actual state of eccentricity creation on the rolling mill. A numerical simulation of piercing under different input conditions was used (software DEFORM-3D) and was performed for several different charge states before entering onto the piercing press. The eccentricity itself has a significant effect on the resulting geometric quality of the tubes.

An Easily Synthesized Covalent Nanocage that Hosts Fullerenes in Multiple Charge States and Selectively Binds C70

Discrete nanocages provide a way to solubilize, separate, and tune the properties of molecular guests, including fullerenes and other aromatics. However, few such nanocages can be synthesized efficiently from inexpensive starting materials, limiting their practical utility. To address this limitation, we developed a new pyridinium-linked cofacial porphyrin nanocage (Cage4+) that can be prepared efficiently on a gram scale. NMR studies in CD3CN reveal that Cage4+ binds C60 and C70 with association constants >108 M-1 and complete selectivity for extracting C70 from mixtures of both fullerenes. The solubility of Cage4+ in polar solvents enabled electrochemical characterization of the host-guest complexes C60@Cage4+ and C70@Cage4+, finding that the redox properties of the encapsulated fullerenes are minimally affected despite the positive charge of the host. Complexes of the −1 and −2 charge states of the fullerenes bound in Cage4+ were subsequently characterized by UV-vis-NIR and NMR spectroscopies. The relatively easy preparation of Cage4+ and its ability to bind fullerenes without substantially affecting their redox properties suggests that C60@Cage4+ and C70@Cage4+ may be directly useful as solubilized fullerene derivatives.

The use of aluminum oxide as a sensor

The comes about of optical and photoluminescence properties of anodic alumina shaped within the acidic electrolyte and subjected to high-temperature warm treatment are depicted in article. It was found that the photoluminescence properties of anodic alumina decided by the oxygen opportunities with diverse values of the charge states and pollutions within the frame of corrosive buildups. As a premise of limit finders in terms of the mechanical quality the substrates shaped within the oxalic electrolyte and altered by warm treatment at 800 °C are preferred. Variations of plans dilatometric microrelays sensors of temperature based on anodic alumina are advertised. For different ranges of temperatures and working conditions ideal plans are chosen.

Marcus inverted region of charge transfer from low-dimensional semiconductor materials

A key process underlying the application of low-dimensional, quantum-confined semiconductors in energy conversion is charge transfer from these materials, which, however, has not been fully understood yet. Extensive studies of charge transfer from colloidal quantum dots reported rates increasing monotonically with driving forces, never displaying an inverted region predicted by the Marcus theory. The inverted region is likely bypassed by an Auger-like process whereby the excessive driving force is used to excite another Coulomb-coupled charge. Herein, instead of measuring charge transfer from excitonic states (coupled electron-hole pairs), we build a unique model system using zero-dimensional quantum dots or two-dimensional nanoplatelets and surface-adsorbed molecules that allows for measuring charge transfer from transiently-populated, single-charge states. The Marcus inverted region is clearly revealed in these systems. Thus, charge transfer from excitonic and single-charge states follows the Auger-assisted and conventional Marcus charge transfer models, respectively. This knowledge should enable rational design of energetics for efficient charge extraction from low-dimensional semiconductor materials as well as suppression of the associated energy-wasting charge recombination.

Low-Frequency Admittance of Capacitor with Working Substance “Insulator–Partially Disordered Semiconductor– Insulator”

The study of the electrophysical characteristics of crystalline semiconductors with structural defects is of practical interest in the development of radiation-resistant varactors. The capacitance-voltage characteristics of a disordered semiconductor can be used to determine the concentration of point defects in its crystal matrix. The purpose of this work is to calculate the low-frequency admittance of a capacitor with the working substance “insulator–crystalline semiconductor with point t-defects in charge states (−1), (0) and (+1)–insulator”. A layer of a partially disordered semiconductor with a thickness of 150 μm is separated from the metal plates of the capacitor by insulating layers of polyimide with a thickness of 3 μm. The partially disordered semiconductor of the working substance of the capacitor can be, for example, a highly defective crystalline silicon containing point t-defects randomly (Poissonian) distributed over the crystal in charge states (−1), (0), and (+1), between which single electrons migrate in a hopping manner. It is assumed that the electron hops occur only from t-defects in the charge state (−1) to t-defects in the charge state (0) and from t-defects in the charge state (0) to t-defects in the charge state (+1).In this work, for the first time, the averaging of the hopping diffusion coefficients over all probable electron hopping lengths via t-defects in the charge states (−1), (0) and (0), (+1) in the covalent crystal matrix was carried out. For such an element, the low-frequency admittance and phase shift angle between current and voltage as the functions on the voltage applied to the capacitor electrodes were calculated at the t-defect concentration of 3∙1019 cm−3 for temperatures of 250, 300, and 350 K and at temperature of 300 K for the t-defect concentrations of 1∙1019, 3∙1019, and 1∙1020 cm−3.

Electron Ionization of Size-Selected Positively and Negatively Charged Helium Droplets

A beam of size-selected charged helium droplets was crossed with an electron beam, and the ion efficiency curves for the product droplets in all different charge states were recorded. We estimate that the selected helium droplets on their passage through the electron beam are hit by several hundred electrons which can interact with the individual He atoms of the droplets. Reaction channels corresponding to the removal or capture of up to eight electrons were identified, and in all cases, inelastic scattering and the formation of metastable helium played a significant role.

Quantifying charge state heterogeneity for proteins with multiple ionizable residues

For proteins with multiple ionizable residues, the canonical assumption is that ionization states of residues are fixed by their intrinsic pKa values. However, several studies have shown that protonation / deprotonation of acidic vs. basic sidechains is realizable even when the solution pH is kept fixed at values that are far away from the intrinsic pKa values. Indeed, protein solutions are best described as ensembles of charge microstates, with each member of the ensemble being a distinct charge microstate defined by differences in charge states for ionizable residues. Accordingly, for a given set of solution conditions, the true partition function is sum over all charge microstates and all the Boltzmann weights of all conformations associated with each of the charge microstates. Here, we leverage the advantages afforded by potentiometric titrations to measure global net charge as a function of pH, independent of considerations of conformational preferences. The systems studied are fragments of proteins with repetitive patterns of Lys and Glu. We analyze the potentiometry data using the recently introduced formalism of the q-canonical ensemble. In this ensemble, charge microstates can be grouped into mesostates. Each mesostate is a collection of microstates of the same net charge. We analyze data for global charge vs. pH to extract mesostate populations as a function of pH. Our findings reveal that the heterogeneity of charge states makes significant contributions to measured charge profiles. This has significant implications for the types of species that are present in solution, even for a fixed pH. Measurements of net charge, decoupled from measurements of conformational equilibria, and analyzed to extract the pH-dependent populations of different mesostates, will be significant for accurate understanding of how charge state heterogeneity contributes to conformational, binding, and phase equilibria of proteins, especially those that are intrinsically disordered.