Study of projectile fragmentation in the reaction (158 A GeV) Pb + Pb using CR-39

The fragmentation of Pb ions at 158 A GeV energy produced in the interaction with Pb target has been studied using a CR-39 track detector. A stack comprising of 64 detectors was prepared such that a target of 1 cm thickness was sandwiched between the sheets of CR-39. The purpose of this exposure geometry was to calibrate CR-39 with respect to relativistic heavy ions as well as to study the fragmentation of Pb ions at 158 A GeV energy. The exposure was carried out at the SPS beam facility of CERN at normal incidence with a fluence of . Two detectors from the exposed stack have been selected for this study: one before and the other after the target material. After etching, the detectors were scanned using an optical microscope and the etched track lengths and the diameters of the track openings were measured manually. Considering that the lengths of tracks provide the best charge resolution for Z>65, we have measured track lengths for a sufficiently large number of fragments to identify individual charge states for 65<Z<83. The total charge-changing cross section has also been determined.     

Stability of localized solutions under rigid loading in a heuristic buckling model

The stability of static localized buckling solutions which bifurcatefrom the critical load for a strut on an elastic foundationis analysed under conditions of rigid loading (i.e. with prescribedend shortening) using a non-periodic modal analysis. The characteristicof such deflection patterns is in marked contrast with stabilityunder the more straightforward case of dead loading (behaviourunder prescribed load). The model presented incorporates initialdestabilization and subsequent restabilization of the responseat the lowest order.     

An application of a fixed point theorem to best simultaneous approximation

Using a recent result regarding the fixed points of multivalued mappings, the existence of invariant best simultaneous approximation in chainable metric space is proved.     

High throughput synthesis of diverse 2,5-disubstituted indoles using titanium carbenoids bearing boronate functionality

A titanium benzylidene complex bearing a boronate group converted resin-bound esters into enol ethers. Suzuki cross-coupling with aryl iodides followed by cleavage with acid completed the solid-phase synthesis of 2,5-disubstituted N-Boc-indoles. Also reported is the use of tert-butyllithium and 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane to convert an aryl bromide into an arylboronate in the presence of a dithiane, with simultaneous reduction of an aryl azide to an amine.     

Simultaneous determination of potassium clavulanate and cefixime in synthetic mixtures by high-performance liquid chromatography

A simple, precise, and sensitive high-performance liquid chromatographic method was developed and validated for the simultaneous determination of potassium clavulanate and cefixime in synthetic mixture form. The analytes were separated on a C18 column by using 0.03 M disodium hydrogen phosphate buffer (pH 6.5)-methanol (84 + 16, v/v) as the mobile phase with detection at 220 nm. The method exhibited high sensitivity and good linearity in the concentration ranges of 12.5-62.5 and 20-100 microg/mL for potassium clavulanate and cefixime, respectively. The total run time for the 2 components was <8 min, and the average recovery was >101.5% with a relative standard deviation of <1.0%. The proposed method was validated according to guidelines of the International Conference on Harmonization by evaluation of linearity, recovery, selectivity, robustness, limits of detection and quantitation, and within- and between-day precision. The results obtained for the synthetic mixture show that the method is highly precise and accurate for the simultaneous determination of potassium clavulanate and cefixime.     

Fixed points for generalized contractions and applications to control theory

The concepts of “weak/strong topological contraction” and a generalization of Banach contraction mappings called “p$p$-contraction” are introduced and used to prove fixed point theorems for self-mappings from a topological/metric space into itself satisfying topological contraction/metric p$p$-contraction, respectively. Certain non-linear integral equations defined on C[a,b]$C[a,b]$ satisfying generalized Lipschitzian conditions can easily be solved by applying these theorems. In the sequel, we shall study the possibility of optimally controlling the solution of the ordinary differential equation via dynamic programming.     

Deterioration of the Strong sp2 Carbon Network in Carbon Nanotubes during the Mechanical Dispersion Processing—A Review

The unique mechanical, thermal, and electrical properties of carbon nanotubes (CNTs) make them an ideal reinforcement for the metal matrix composites (MMCs). The successful incorporation of CNTs as reinforcement in MMCs can result in the development of lightweight and high-strength structures which can eventually result in weight savings for the automobile and aerospace industries. In the last two decades extensive research has been carried out to improve the dispersion of CNTs in metal and polymer matrices. Challenges remain to effectively disperse CNTs within the matrix materials with minimal damage during the composite processing stages. The ultra-high Young's modulus and other superior mechanical and thermal properties of CNTs have been attributed to the strong sp² A. M. Esawi and M. A. El Borady, Carbon nanotube-reinforced aluminium strips. Compos. Sci. Technol. 68, 486 (2008).[Crossref], [Web of Science ®] , [Google Scholar] carbon-carbon (C-C) bonds present in their structures. In order to fully utilize the unique properties of CNTs as reinforcement, damages to CNTs in the form of damaging these sp²C-C bonds have to be minimized. A variety of processing techniques have been developed to fabricate CNTs reinforced MMCs but mechanical alloying (MA) via powder metallurgy (PM) is most widely used process to develop the nano-composites. The role of processing variables during PM and their effects on the structural integrity of CNTs have been reviewed in this work. Governing principles to predict the mechanical properties of CNTs with incorporating the key process variables are deduced. With the help of these governing equations, critical study of the processes parameters and their effects on the structural integrity of CNTs, it is possible to optimize the processing methodologies of CNTs reinforced MMCs and get the maximum benefit from the unique properties of CNTs. It is assumed that better dispersion of CNTs in the metal matrices, retaining the structural integrity of CNTs and optimization of process parameters would result in better mechanical and tribological properties of CNTs reinforced MMCs.     

Structural and Magnetic Properties of Chemically Synthesized Pd-Modified NiFe2O4 Nanoparticles

Magnetic nanoparticles of NiFe₂O₄-Pd composites have been synthesized using a simple, low cost, sol-gel auto-combustion method. As-prepared samples were sintered at 800 ℃ for 6 h in order to develop the crystalline phase. X-ray diffraction confirmed the spinel structure of the ferrite samples. Structural morphology and size of the nanoparticles were evaluated using a field emission scanning electron microscope. Magnetic hysteresis loops were obtained at 300 and 100 K using a physical properties measurement system. The value of saturation magnetization was observed to decrease at the temperatures with the increase of Pd contents up to 5% but then a sudden rise in saturation magnetization was observed for the addition of 10% Pd in NiFe₂O₄.     

Synthesis and characterization of room temperature sol–gel-assisted transparent tin-doped magnesium oxide nanoparticles’ protective coating

Journal of Sol-Gel Science and Technology - Using in-situ sol–gel processing, Sn-doped MgO2 nanofilm has been fabricated by spin-coating technique. Cracked and uneven distribution of...     

Structural Properties of Cubic Sets in Regular LA-semihypergroups

In this article we characterize the regular LA-semihypergroups in terms of $({\in }_{\Gamma },{\in }_{\Gamma }\vee q_{\Delta })$-cubic (left, right, two sided, bi, generalized bi, interior, quasi)-hyperideals of LA-semihypergroups. Meanwhile, some illustrative examples are given to show the rationality of the definitions popularized in the present paper.