Applications In Fields Of Science Research Articles

Study of Degenerate Four-Wave Mixing in Disperse Orange Dye-Doped Polymer Film

Nonlinear optical phase conjugation by degenerate four-wave mixing (DFWM) is an important technique with applications in many fields of science and technology. Phase conjugation by Degenerate four-wave mixing is observed in Disperse Orange-25 dye doped in Polymethyl methacrylate – metacrylic acid (PMMA-MA) polymer film under low-power, continuous-wave laser irradiation. A maximum phase conjugate efficiency of 0.22% has been obtained for probe beam intensity at 0.11 W/cm2. Phase conjugation is observed for both parallel- and orthogonally-polarized probe and pump beams. The maximum PC reflectivity is achieved when the angle between probe and forward pump beam is 7 degrees. The effects of dye concentration, intensity of backward, forward pump and inter beam angle between probe and forward pump beam on phase conjugation reflectivity are also studied. PC signal strength first increases and then decreases. PC reflectivity is increased by increasing the intensity of the backward and forward pump beam. The polarization and intensity profile are verified to be preserved in the conjugate signal. The predominant phase conjugation signal is attributed to the facts that reverse saturable absorption and large third order susceptibility of the dye molecules.

High intensity positron source at HFR: Basic concept, scoring and design optimisation

Recent applications of positron beam techniques in various fields of research have led to an increasing demand for high intensity positron sources required for advanced applications, particularly in materials science. Considerable efforts are being made worldwide to design and set-up high intensity positron sources and beam systems that are based on several principles. Such positron sources could be used in fundamental and applied research experiments, as well as in industrial applications, especially in the field of condensed matter characterisation at the nanometre scale. Phenomena involving positrons are also important in other applied science fields such as medicine, biology, physics, energy, etc. However, such studies are often limited due to the relative lack of suitable positron sources. Results from the recently completed Exploratory Research Project called “HIPOS” are discussed in this paper, which describes the principles behind such a powerful very high intensity positron beam experimental facility that is based on a reactor source. Details of a proposed concept that uses nuclear reactions [(n, γ) and (γ, pair)] within a designed positron generator at the High Flux Reactor (HFR) in Petten are also discussed. The HIPOS source has been designed to produce slow positrons with intensity of the order of 10 10 e +/s.

Benoit Mandelbrot and Fractals in Art, Science and Technology

Benoit Mandelbrot, recently deceased French and American mathematician, was born in Warsaw in 1924. In 1936 he and his family fled the Nazis and in France joined his uncle Szolem Mandelbrojt, professor of mathematics at College de France. After attending Ecole Polytechnique, he studied linguistics and proved Zipf’s law. He was an extremely original scientist who with the invention of fractals created a new concept with applications in numerous fields of science and art. His unconventional approach was well accepted when he came to IBM in 1958. He was also a professor at Yale University (1999–2005). In 1981 he published an article in Leonardo [1]. The concept of fractals unites and gives a solid mathematical framework, as Mandelbrot liked to emphasize, to ideas that artists, scientists and philosophers of art have sometimes intuited more or less clearly. Let me start with this striking quotation from Eugene Delacroix’s Journal in 1857:

Progress and application of flow focusing

Flow focusing (FF) is one of capillary flows, which is first proposed in 1998, characterized by the formation of a steady meniscus in the core of an extensional high-speed fluid focused by a small hole when a fluid is injected through a capillary needle. A very thin jet is issued from the vertex of the meniscus, passes through the hole and breaks up into monodisperse droplets at a certain distance outside the hole. The FF technique is steady, controllable and does not require rigorous conditions in producing microparticles, such as droplets, bubbles, particles and capsules down to the micrometer dimension and below. It has important applications in fields of science, technology and engineering. This paper reviews the progress of flow focusing involving experiments, theories and numerical simulations. The applications are also briefly reviewed. Finally, some future issues are presented.

Peculiarities of the decoration of carbon nanotubes with transition metal atoms

Carbon nanotubes decorated with transition metal, in particular, scandium, titanium, and vanadium, atoms offer promise for use in various applied science fields. We report the results of quantum-chemical calculations of the structure of the metallic layer of atoms of these metals coating the surface of (9, 0) and (10, 0) carbon nanotubes. It was shown that uniform one-layer coating by scandium and titanium could form on nanotubes with diameters no less than the diameter of (10, 0) nanotubes. Vanadium atoms could not uniformly cover nanotubes irrespective of their diameters.

Foldover Conference Designs for Screening Experiments

A conference matrix is a square matrix C with zeros on the diagonal and ±1s off the diagonal, such that C T C = CC T = (n − 1)I, where I is the identity matrix. Conference matrices are an important class of combinatorial designs due to their many applications in several fields of science, including statistical-experimental designs, telecommunications, elliptic geometry, and more. In this article, conference matrices and their full foldover design are combined together to obtain an alternative method for screening active factors in complicated problems. This method provides a model-independent estimate of the set of active factors and also gives a linearity test for the underlying model.

Swelling and shrinking of porous materials: from colloid science to poromechanics

Electrochemical interaction between colloidal particles and an aqueous solution is a central subject in Colloid Science. Such interactions give rise to electrokinetic phenomena in electrically charged porous media, and have received considerable attention with a wide range of applications in different fields of science and engineering. Several porous materials composed of electrically charged macromolecules saturated by saline solutions may undergo swelling by fresh water uptake. Among this class of colloidal systems, we highlight 2-1 lattice clays, hydrophilic polymers, gels, shales, corneal endothelium and connective biological tissues. For example, the response of smectite 2:1 clay particles to changes in water content has been studied for decades. Such phenomenon plays a critical role in the quality of groundwater, in the effectiveness of some clean up technologies and in the distribution of plants and nutrients in the Earth’s crust. Clay swelling (or collapse) is of widespread relevance in geotechnical and geoenvironmental fields. Upon inundation, it may have undesired consequences, as they heave upward upon hydration (or shrink upon desiccation) causing damage to the foundations of buildings ranging from minor cracking to irreversible displacements of footings. Moreover, swelling and deterioration of shales are the major contributors to drilling problems and are key factors in the wellbore stability management. Finally, due to their low hydraulic conductivity, plasticity, swelling and adsorptive capacity for contaminants, bentonitic based compacted clays have been used as sealing materials to inhibit the migration of contaminants to the environment, and have been also considered to investigate the disposal of high-level radioactive waste in various countries. Beyond applications in natural geomaterials, swelling polymers/biopolymers have numerous technological applications, such as size exclusion chromatography, gel electrophoresis in filtration processes, development of efficient drug delivery substrates, in contact lenses, in semiconductor manufacturing and in food stuffs. In biomedical technology, electrical interactions between ions and negatively charged proteoglycans rule the deformation of cartilaginous soft hydrated tissues as load-bearing structures. The swelling property is tied-up to the physiological states of soft connective tissues (articular cartilage and intervertebral disk) and plays an important role in articulating joint lubrication and damping of dynamic forces in the human body. The fundamental thermodynamic processes underlying electrokinetic phenomena involve several couplings, such as: transport of mobile ions near charged surfaces (electro-migration), flow and motion of charged particles driven by an electric field (electro-osmosis and electrophoresis), dissolution/precipitation reactions, electrolysis of water, sorption, desorption and protonation/deprotonation chemical reactions. Owing to their complexity, it is imperative that any macroscopic model describing these electro-chemo-mechanical interactions inherent to this type of system contains accurate constitutive relations. During the past few decades, a significant amount of research has been developed towards the derivation of models capable of capturing coupled electro-chemo-hydro-mechanical effects in charged porous media. Owing to the aforementioned complex fine-scale electro-chemical interactions, the accuracy of purely macroscopic models

Optics of surface disordered systems

No surface is perfectly flat at every length scale. However, all natural and man-made surfaces show some degree of roughness. Therefore, it is imperative to know how surface disorder may affect physical process at, or in the immediate vicinity, of the surface. In this review, we focus on the long-standing problem of electromagnetic wave scattering from randomly rough surfaces. This topic has implications and practical applications in fields of science and engineering ranging from observational astronomy to the electronic and medical industry. How randomly rough surfaces can be described statistically is outlined, and we introduce the theoretical and computational methods most frequently used in the study of light scattering from randomly rough metal or dielectric surfaces. A large part of the review is devoted to the description and the discussion of the physical origin behind various multiple scattering phenomena that can exist when light interacts with a random surface. Some of the addressed phenomena are; the enhanced backscattering and satellite peak phenomena; forward scattering (specular peak) enhancement; coherent effects in the angular intensity correlation functions and the second harmonic generated light (nonlinear effect).

Uses of Meta‐Analysis in Criminal Justice Research: A Quantitative Review

Meta‐analysis has been adopted in many scientific fields for synthesizing large bodies of research, for evidence‐based development of practical policies, and for empirical resolution of difficult questions. It provides a rigorous, objective, and quantitative strategy to make effective use of an existing body of research, even when the results seem inconsistent and inconclusive. This paper reviews usage of meta‐analysis in research on criminal justice‐related issues and problems over the past three decades, identifying 176 studies published between 1976 and 2006 using meta‐analysis methods on criminal justice topics. Characteristics of these 176 studies are coded and analyzed to identify trends in the use of meta‐analysis by criminal justice researchers, as well as to summarize distinctive variations in how it has been used. A comparison of criminal justice with meta‐analysis usage in other social and applied science fields suggests some hesitation in adopting the methodology.

Organic mass spectrometry at the beginning of the 21st century

Mass spectrometry in the last 15–20 years has become one of the first methods of the qualitative analysis and quantitative determination of various substances, from isotopes of chemical elements to synthetic polymers, proteins, and nucleic acids. This method allows analysts to work with both individual compounds and most complex mixtures that contain hundreds and thousands of compounds. It is the best in terms of the sensitivity, information content, and rapidity. This review covers the present-day achievements of mass spectrometry, including ionization and ion separation methods and different versions of its application in various fields of science and human activity.

MULTPATH: A Comprehensive Minitab Program for Computing Path Coefficients and Multiple Regression for Multivariate Analyses

ABSTRACT Path analysis has applications in various fields of science, including social science, economics, agriculture, and biology. While programs for path analysis written in other computer languages are available, no program for Minitab exists even though Minitab plays an important role in numerous branches of science for statistical analyses. The aim of this paper is to present a powerful Minitab program, MULTPATH, for path analysis. This program responds well to Minitab versions V10.5 and higher. To demonstrate its operation, an artificial data set is used. The macro yields results similar to those obtained using other statistical software, such as SAS. The macro should be useful to researchers from most fields of study, including biologists and agriculturists. A program copy is available free of charge from the corresponding author.

Formation of nanostructures during laser-induced melting of solid surfaces

In recent years, nanostructures in solids have begun to receive more attention from researchers as important objects having very promising applications in various fields of science and technology. Ordered and disordered ensembles of nanoparticles represent new artificial materials with a broad range of applications due to their unique properties. The nanostructured surfaces improve the electrical, thermal, and electron-emission properties of materials and lead to better compatibility of tissues with implants used in orthopedics and dentistry. They also find application in selective nanocatalysis, microelectronics, nanophotonics, spectroscopy, and high-power optics; ensure superhigh data recording density; and are used in developing light-emitting silicon-base devices. This implies a need for developing the physical foundations of new effective methods for the formation of two- and three-dimensional structures with characteristic sizes less than one micrometer both at the surface and in the bulk of solids and for studying the mechanisms of nanostructure formation, which can be of various natures. In this study, the possibility of forming nanostructures at solid surfaces by laser pulses leading to the melting of the material surface is evaluated. The action of a laser pulse with a certain energy density and duration on a solid surface can lead to the melting of the surface layer. Let us consider the process of its solidification due to subsequent heat removal in the depth of the solid phase. In this case, the liquid turns out to be in the supercooled state and a considerable temperature difference across the liquid‐solid interface is established. Depending on the degree of supercooling, the subsequent nucleation of the crystal phase can have either a fluctuational [1] or a spontaneous [2] character (Fig. 1). The variation of the thermodynamic potential during the formation of a new phase center (nucleus) consisting of n atoms can be described as follows:

Giant unilamellar vesicle formation under physiologically relevant conditions

We present an upgrade to the giant unilamellar vesicle (GUV) electroformation method allowing easy GUV production in different buffers and with various membrane compositions. Our experimental results reveal that lipid deposits obtained from aqueous liposome or proteoliposome dispersions are highly efficient for GUV electroformation. This is related to the ability of such dispersions to produce readily well-oriented membrane stacks. Furthermore, we present a protocol for GUV electroformation in various aqueous media, including electrolyte-containing buffers at characteristic concentrations of biological fluids. This work unlocks historical barriers to GUV applications in scientific fields like biology, biochemistry, or biophysics where membrane composition, as well as its aqueous environment, should be adapted to biological significance.

Significance of nanotechnology in medical sciences

Nanotechnology refers broadly to a field of applied science and technology whose unifying theme is the control of matter on the molecular level in scales smaller than 1 μm, normally 1-100 nm, and the fabrication of devices within that size range. Two main approaches are used in nanotechnology. In the “bottom-up” approach, materials and devices are built from molecular components, which assemble themselves chemically by principles of molecular recognition. In the “top-down” approach, nano-objects are constructed from larger entities without atomic-level control. In addition, as the need for the development of new medicines is pressing, and given the inherent nanoscale functions of the biological components of living cells, nanotechnology has been applied to diverse medical fields such as oncology, cardiovascular medicine, and in treatment of other chronic diseases. Indeed, nanotechnology is being used to refine discovery of biomarkers, molecular diagnostics, and drug discovery and drug delivery, which could be applicable to management of these patients. In this review, we will focus upon significance of nanotechnology in medical sciences, as well as the plausible side effects related to their use.

Recent Progress on Squaric Acid Research in Bioorganic Fields

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Recent Progress on Squaric Acid Research in Bioorganic Fields

Squaric acid belongs to a class of oxocarbons and exhibits unique physicochemical properties, e.g., strong acidity, aromaticity, strained ring, electron deficiency, and metal chelating ability. Squaric acid has received considerable attention as a carboxylic acid mimic in medicinal chemistry, a novel chromophore in material science, a new chelator in inorganic chemistry, and a building block of quinones, triquinanes, cyclopentenones, and furanones in organic synthesis. Recently, squaric acid diesters are employed for a variety of applications in scientific fields as a linker to construct novel bioconjugate molecules. This review will describes recent progress on the use of squaric acid focused on bioorganic research.

Effect of Solvent Concentration to the Preparation of Polystyrene Nanoparticles Using Polyelectrolyte Block Copolymer

ABSTRACTParticles of sizes within the nano region have attracted many applications in different fields of science. In this study, the self assembly property in a selective solvent of block copolymers has been used for the preparation of polystyrene nanospheres. Sulfonated Styrene-Butadiene-Styrene (SSBS) tri block copolymer was used as a polymeric surfactant for synthesis of uniformly sized polystyrene nanoparticles using emulsion polymerization. The effects of initiator, monomer and block copolymer concentration to the molecular weight distribution and size distribution were investigated. Uniformly sized nanoparticles with a polydispersity index of 1.004 and diameter of 112.9nm was verified by Dynamic Light Scattering (DLS) and Scanning Electron Microscopy (SEM), respectively. Using a mixed continuous phase solution of water and methanol, it was found out that the particle size decreased relative to the increase of methanol added to the reaction solution. Associating behavior of the polyelectrolyte block copolymer in the binary solvent environment regarding size of micelle formed was reflected on the properties of the nanospheres. Nanoparticles prepared with greater methanol concentration were observed to be less than 100 nm. Size distribution was also observed to be narrower in proportion to MeOH concentration.

A note on the existence of solutions to some nonlinear functional integral equations

Substituting the usual growth condition by an assumption that a specific initial value problem has a maximal solution, we obtain existence results for functional nonlinear integral equations with variable delay. Appli- cation of the technique to initial value problems for differential equations as well as to integrodifferential equations are given. Nonlinear integral equations and nonlinear functional integral equations have been some topics of great interest in the field of nonlinear analysis for a long time. Since the pioneering work of Volterra up to our days, integral equations have attracted the interest of scientists not only because of their mathematical context but also because of their miscellaneous applications in various fields of science and technology. In particular, existence theory for nonlinear integral equations, strongly related with the evolution on fixed point theory, has been boosted ahead after the remarkable work of Krasnoselskii (6) which signaled a new era in the research of the subject. The present note is motivated by a recent paper by Dhage and Ntouyas (3) presenting some results on the existence of solutions to the nonlinear functional integral equation (E)

A hybrid algorithm for computing permanents of sparse matrices

The permanent of matrices has wide applications in many fields of science and engineering. It is, however, a #P-complete problem in counting. The best-known algorithm for computing the permanent, which is due to Ryser [Combinatorial Mathematics, The Carus Mathematical Monographs, vol. 14, Mathematical Association of America, Washington, DC, 1963], runs O(n2^n^-^1) in time. It is possible to speed up algorithms for matrices with special structures, which arise commonly in applications. Most algorithms discussed before focus on 0,1 matrix. In this paper, a hybrid algorithm is proposed. It is efficient for sparse matrices.

Tunable THz Sources and Their Applications

In this paper, the technology aspects of the THz laser and spectrometric devices, developed over the last decade are described and their applications in various fields of science and technology are explained. The THz sources of importance are the optically pumped lasers, solid state devices and the backward wave oscillator (BWO) based systems. The BWO system offers the electronic tuning and multiplexing facility like Fourier transform technology. The time resolved and frequency domain aspects with relative merits are discussed. Non-linear optical methods of production of monochromatic radiation using second harmonic generation (SHG) are also considered. The important areas of space applications are described in detail. Present status and future directions are indicated.