Structure of Se–Te glasses by Raman spectroscopy and DFT modeling

For the first time, the Raman spectra of bulk Se_xTe_1‐x glasses, 0.5 ≤ x ≤ 1.0, have been measured over the entire glass‐forming range. The spectra exhibit three broad spectral features between 150 and 300 cm^?1, attributed to Te–Te, Se–Te, and Se–Se stretching modes according to DFT simulations. The observed weak chemical ordering in the glasses is discussed on the basis of heteropolar and homopolar bond fractions derived from integrated intensity of the Raman modes and DFT cross‐sections. The underlying structural model of the glasses suggests a random distribution of the Se–Se, Se–Te, and Te–Te chemical bonds with some preference for heteropolar bonding within Se–Te–Se structural units.     

Self‐assembled amphiphilic poly‐N‐vinylpyrrolidone nanoparticles as carriers for hydrophobic drugs: Stability aspects

Nanoparticles can experience numerous impacts during storage or after intravenous administration resulting in disassembly and/or drug leakage and affecting their efficiency as drug delivery systems. In this study, this crucial issue was addressed by investigating the stability of amphiphilic poly‐N‐vinylpyrrolidone derivative nanocarriers in blood serum, against destabilizing agents and during long‐term storage. All amphiphilic poly‐N‐vinylpyrrolidone derivative nanoparticles prepared in this study were found to possess sizes less than 150 nm, narrow size distribution, spherical morphology, and a slightly negative surface charge. These nanoparticles could efficiently entrap hydrophobic substances (pyrene and curcumin) while retaining excellent compatibility with red blood cells. Moreover, our studies demonstrate the stability of the nanoparticles during long‐term storage and upon dilution with body liquids enhancing their potential as stable in vivo carriers, which is critically important for intravenous drug delivery applications. All properties were found to strongly depend on the ratio between the hydrophobic and the hydrophilic moiety of the polymers under study. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45637.     

Benzotriazinyl‐mediated controlled radical polymerization of styrene

The stable free radical polymerization (SFRP) process based on (1,3‐diphenyl‐1,4‐dihydro‐1,2,4‐benzotriazin‐4‐yl), the so‐called ‘Blatter radical’, and several C‐7 substituted derivatives is introduced for the first time for the polymerization of styrene. Polystyrenes characterized by polydispersity indices in the 1.05 ? 1.27 range were obtained in the presence of the Blatter radical and its derivatives containing CF₃, Ph, Fur‐2‐yl and 4‐PhC₆H₄ substituents, while polymerization proceeded either in a non‐controlled manner or in very low polymerization yields in the presence of derivatives containing halogen (Cl, Br, I) substituents. This preliminary investigation, demonstrating the potential use of the Blatter radical and its derivatives in mediated SFRP, creates new opportunities to design and develop radicals to optimize performance in such polymerization processes. © 2013 Society of Chemical Industry     

Malignant Ascites Promote Adhesion of Ovarian Cancer Cells to Peritoneal Mesothelium and Fibroblasts

Although malignant ascites (MAs) are known to contribute to various aspects of ovarian cancer progression, knowledge regarding their role in the adhesion of cancer cells to normal peritoneal cells is incomplete. Here, we compared the effect of MAs and benign ascites (BAs) on the adhesion of A2780 and OVCAR-3 cancer cells to omentum-derived peritoneal mesothelial cells (PMCs) and peritoneal fibroblasts (PFBs). The results showed that MAs stimulated the adhesion of A2780 and OVCAR-3 cells to PMCs and PFBs more efficiently than did BAs, and the strongest binding occurred when both cancer and normal cells were exposed to the fluid. Intervention studies showed that MAs-driven adhesion of A2780 cells to PMCs/PFBs depends on the presence of TGF-β1 and HGF, whereas binding of OVCAR-3 cells was mediated by TGF-β1, GRO-1, and IGF-1. Moreover, MAs upregulated α5β1 integrin expression on PFBs but not on PMCs or cancer cells, vimentin expression in all cells tested, and ICAM-1 only in cancer cells. When integrin-linked kinase was neutralized in PMCs or PFBs, cancer cell adhesion to PMCs and PFBs decreased. Collectively, our report shows that MAs may contribute to the early stages of ovarian cancer metastasis by modulating the proadhesive interplay between normal and cancer cells.     

Linseed and Complex Rosin Ester Oils Additivated with MWCNTs and Nanopearls for Gears/Wheel‐Rail Systems

An innovative biolubricant for gears/wheel‐rail systems is formulated; it is produced inexpensively using high‐viscosity vegetable oils modified with additives of unpurified carbon nanopearls (CNPs) and MWCNTs produced via carbon‐vapor deposition. Traditional lubricants made from non‐renewable sources can be replaced with such additive‐based oils. The addition of both unpurified carbon nanopearls and nanotubes containing nanoparticles of Fe, Ni, Co, or SiO₂ is a simple way to improve the tribological properties of biolubricants. Therefore, carbon nanostructures used as additives are not required to be purified or functionalized, thus reducing production costs. Tribological testing is performed with ball‐on‐disc, four‐ball, and twin‐disc machines for two high‐viscosity biolubricants. A complex rosin ester and linseed oil additivated with commercial and raw CNPs/MWCNTs are tested. Scanning electron microscope characterization is used to assess the morphology and structure of both the carbon nanopearls and the multiwalled carbon nanotube particles in addition to the worn metal surfaces. Additionally, X‐ray diffraction, FTIR spectroscopy, and inductively coupled plasma atomic emission spectroscopy are used to characterize the MWCNTs additives. Practical Applications: Biolubricant additivation with raw unpurified MWCNTs and CNPs for enhanced tribological performance. Presence of Fe, Ni, Co, and Si nanoparticles helps fine‐tune the friction coefficient and anti‐wear rates. The proposed method may prove useful in biolubricant formulation for applications in gears/wheel‐rail and metal machining systems.     

CW laser-initiated formation of nano-Si crystals in glass-metal nanostructures

Local and controllable growth of nanocrystalline silicon (nano-Si) in a commercial borosilicate glass is demonstrated. The nano-Si was formed in the subsurface region of the glass via aluminothermic reaction in the course of the irradiation of a 2D array of aluminum nanodisks fabricated on the glass surface with CW low-power 633 and 532 nm lasers. The thermoplasmonic nature of the nanodisks heating is demonstrated: at low incident intensity, the phenomenon takes place only if the plasmon resonance of the array and the laser wavelength is close enough. However, when the laser beam intensity at the sample surface exceeds 8 MW/cm² mutual position of the plasmon resonance and the laser wavelength weakly influences the phenomenon. The nano-Si formation is studied with Raman scattering technique, and the average size of the silicon nanocrystals is evaluated.     

An affordable modular mobile robotic platform with fuzzy logic control and evolutionary artificial neural networks

Autonomous robotics projects encompass the rich nature of integrated systems that includes mechanical, electrical, and computational software components. The availability of smaller and cheaper hardware components has helped make possible a new dimension in operational autonomy. This paper describes a mobile robotic platform consisting of several integrated modules including a laptop computer that serves as the main control module, microcontroller‐based motion control module, a vision processing module, a sensor interface module, and a navigation module. The laptop computer module contains the main software development environment with a user interface to access and control all other modules. Programming language independence is achieved by using standard input/output computer interfaces including RS‐232 serial port, USB, networking, audio input and output, and parallel port devices. However, with the same hardware technology available to all, the distinguishing factor in most cases for intelligent systems becomes the software design. The software for autonomous robots must intelligently control the hardware so that it functions in unstructured, dynamic, and uncertain environments while maintaining an autonomous adaptability. This paper describes how we introduced fuzzy logic control to one robot platform in order to solve the 2003 Intelligent Ground Vehicle Competition (IGVC) Autonomous Challenge problem. This paper also describes the introduction of hybrid software design that utilizes Fuzzy Evolutionary Artificial Neural Network techniques. In this design, rather than using a control program that is directly coded, the robot's artificial neural net is first trained with a training data set using evolutionary optimization techniques to adjust weight values between neurons. The trained neural network with a weight average defuzzification method was able to make correct decisions to unseen vision patterns for the IGVC Autonomous Challenge. A comparison of the Lawrence Technological University robot designs and the design of the other competing schools shows that our platforms were the most affordable robot systems to use as tools for computer science and engineering education. © 2004 Wiley Periodicals, Inc.     

DIRAC: A new version of computer algebra tools for studying the properties and behavior of hydrogen-like ions

During recent years, the Dirac package has proved to be an efficient tool for studying the structural properties and dynamic behavior of hydrogen-like ions. Originally designed as a set of Maple procedures, this package provides interactive access to the wave and Green's functions in the non-relativistic and relativistic frameworks and supports analytical evaluation of a large number of radial integrals that are required for the construction of transition amplitudes and interaction cross sections. We provide here a new version of the Dirac program which is developed within the framework of Mathematica (version 6.0). This new version aims to cater to a wider community of researchers that use the Mathematica platform and to take advantage of the generally faster processing times therein. Moreover, the addition of new procedures, a more convenient and detailed help system, as well as source code revisions to overcome identified shortcomings should ensure expanded use of the new Dirac program over its predecessor.

New version program summary

Program title: DIRACCatalogue identifier: ADUQ_v2_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADUQ_v2_0.htmlProgram obtainable from: CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions: Standard CPC license, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 45 073No. of bytes in distributed program, including test data, etc.: 285 828Distribution format: tar.gzProgramming language: Mathematica 6.0 or higherComputer: All computers with a license for the computer algebra package Mathematica (version 6.0 or higher)Operating system: Mathematica is O/S independentClassification: 2.1Catalogue identifier of previous version: ADUQ_v1_0Journal reference of previous version: Comput. Phys. Comm. 165 (2005) 139Does the new version supersede the previous version?: YesNature of problem: Since the early days of quantum mechanics, the “hydrogen atom” has served as one of the key models for studying the structure and dynamics of various quantum systems. Its analytic solutions are frequently used in case studies in atomic and molecular physics, quantum optics, plasma physics, or even in the field of quantum information and computation. Fast and reliable access to functions and properties of the hydrogenic systems are frequently required, in both the non-relativistic and relativistic frameworks. Despite all the knowledge about one-electron ions, providing such an access is not a simple task, owing to the rather complicated mathematical structure of the Schrödinger and especially Dirac equations. Moreover, for analyzing experimental results as well as for performing advanced theoretical studies one often needs (apart from the detailed information on atomic wave- and Green's functions) to be able to calculate a number of integrals involving these functions. Although for many types of transition operators these integrals can be evaluated analytically in terms of special mathematical functions, such an evaluation is usually rather involved and prone to mistakes.Solution method: A set of Mathematica procedures is developed which provides both the non-relativistic and relativistic solutions of the “Hydrogen atom model”. It facilitates, moreover, the symbolic evaluation of integrals involved in the calculations of cross sections and transition amplitudes. These procedures are based on a large number of relations among special mathematical functions, information about their integral representations, recurrence formulae and series expansions. Based on this knowledge, the DIRAC tools provide a fast and reliable algebraic (and if necessary, numeric) manipulation of functions and properties of one-electron systems, thus helping to obtain further insight into the behavior of quantum physical systems.Reasons for new version: The original version of the DIRAC program was developed as a toolbox of Maple procedures and was submitted to the CPC library in 2004 (cf. Ref. [1]). Since then DIRAC has found its niche in advanced theoretical studies carried out in realm of heavy ion physics. With the help of this program detailed analysis has been performed, in particular, for the various excitation and ionization processes occurring in relativistic ion-atom collisions [2], the polarization of the characteristic X-ray radiation following radiative electron capture [3], the correlation properties of the two-photon emission from few-electron heavy ions [4], the spin entanglement phenomena in atomic photoionization [5] and even for exploring the vibrational excitations of the heavy nuclei [6]. Although these studies have conclusively proven the potential of the program, they have also illuminated routes for its further enhancement. Apart from certain source code revisions, demand has grown for a new version of DIRAC compatible with the Mathematica platform. The version presented here includes a wider ranging and more user friendly interactive help system, a number of new procedures and reprogramming for greater computational efficiency.Summary of revisions: The most important new capabilities of the DIRAC program since the previous version are:

1.

The utilization of the Mathematica (version 6.0) platform.

2.

The addition of a number of new procedures. Since the complete list of the new (and updated) procedures can be found in the interactive help library of the program, we mention here only the most important ones:

○

DiracGlobal[] - Displays a list of the current global settings which specify the framework, nuclear charge and the units which are to be used by the DIRAC program.

○

DiracRadialOrbitalMomentum[] - Returns a non-relativistic radial orbital in momentum space for both, the bound and free electron states.

○

DiracSlaterRadial[] - Evaluates the radial Slater integral both, with the non-relativistic and relativistic wavefunctions. In the previous version of the program this procedure was restricted to the non-relativistic framework only.

○

DiracGreensIntegralRadial[] - Evaluates the two-dimensional radial integrals with the wave- and Green's functions both in non-relativistic and relativistic frameworks.

○

DiracAngularMatrixElement[] - Calculates the angular matrix elements for various irreducible tensor operators.

3.

The elimination of some redundant procedures. In particular, the previous version supported evaluation of the spherical Bessel functions, Wigner 3j symbols, Clebsch-Gordan coefficients and spherical harmonics functions. These tools are now superseded by in-built procedures of Mathematica.

4.

The development of a full featured interactive help system which follows the style of the Mathematica Help Pages.

5.

Extensive revision of the source code in order to correct a number of bugs and inconsistencies that have been identified during use of the previous version of Dirac.

The DIRAC package is distributed as a compressed tar file from which the DIRAC root directory can be (re-)generated. The root directory contains the source code and help libraries, a “Readme” file, Dirac_Installation_Instructions, as well as the notebook DemonstrationNotebook.nb that includes a number of test cases to illustrate the use of the program. These test cases, which concern the theoretical analysis of wavefunctions and the fine-structure of hydrogen-like ions, has already been discussed in detail in Ref. [1] and are provided here in order to underline the continuity between the previous (Maple) and new (Mathematica) versions of the DIRAC program.Unusual features: Even though all basic features of the previous Maple version have been retained in as close to the original form as possible, some small syntax changes became necessary in the new version of DIRAC in order to follow Mathematica standards. First of all, these changes concern naming conventions for DIRAC's procedures. As was discussed in Ref. [1], previously rather long names were employed in which each word was separated by an underscore. For example, when running the Maple version of the program one had to call the procedure Dirac_Slater_radial() in order to evaluate the Slater integral. Such a naming convention however, cannot be used in the Mathematica framework where the underscore character is reserved to represent Blank, a built-in symbol. In the new version of DIRAC we therefore follow the Mathematica convention of delimiting each word in a procedure's name by capitalization. Evaluation of the Slater determinant can be accomplished now simply by entering DiracSlaterRadial[]. Besides procedure names, a new convention is introduced to represent fundamental physical constants. In this version of DIRAC the group of (preset) global variables has changed to resemble their conventional symbols, specifically α, a₀, ec, me, c and ?, being the fine structure constant, Bohr radius, electron charge, electron mass, speed of light and the Planck constant respectively. If the numerical evaluator N is wrapped around any of these constants, their numerical values are returned.Running time: Although the program replies promptly upon most requests, the running time also depends on the particular task. For example, computation of (radial) matrix elements involving components of relativistic wavefunctions might require a few seconds of a runtime. A number of test calculations performed regarding this and other tasks clearly indicate that the new version of Dirac requires up to 90% less evaluation time compared to its predecessor.References:

[1]

A. Surzhykov, P. Koval, S. Fritzsche, Comput. Phys. Comm. 165 (2005) 139.

[2]

H. Ogawa, et al., Phys. Rev. A 75 (2007) 1.

[3]

A.V. Maiorova, et al., J. Phys. B: At. Mol. Opt. Phys. 42 (2009) 125003.

[4]

L. Borowska, A. Surzhykov, Th. Stöhlker, S. Fritzsche, Phys. Rev. A 74 (2006) 062516.

[5]

T. Radtke, S. Fritzsche, A. Surzhykov, Phys. Rev. A 74 (2006) 032709.

[6]

A. Pálffy, Z. Harman, A. Surzhykov, U.D. Jentschura, Phys. Rev. A 75 (2007) 012712.