Tensor and Torsion Products of Relative Injective Modules with Respect to a Semidualizing Module

Let R be a commutative Cohen–Macaulay ring, and let C be a semidualizing module of R. In this paper, we show that C is generically dualizing if and only if the tensor products of injective and C-injective R-modules are injective. This leads to a characterization of dualizing modules as well as generalizes a result of Enochs and Jenda.     

Intersection Matrices Revisited

Several intersection matrices of s‐subsets versus k‐subsets of a v‐set are introduced in the literature. We study these matrices systematically through counting arguments and generating function techniques. A number of new or known identities appear as natural consequences of this viewpoint; especially, use of the derivative operator and some related operators reveals some connections between intersection matrices and the “combinatorics of creation‐annihilation.” As application, the eigenvalues of several intersection matrices including some generalizations of the adjacency matrices of the Johnson scheme are derived; two new bases for the Bose–Mesner algebra of the Johnson scheme are introduced and the associated intersection numbers are obtained as well. Finally, we determine the rank of some intersection matrices. © 2012 Wiley Periodicals, Inc. J. Combin. Designs 20: 383–397, 2012     

Low irradiance background limited type-II superlattice MWIR M-barrier imager

We report a type-II superlattice mid-wave infrared 320×256 imager at 81 K with the M-barrier design that achieved background limited performance (BLIP) and ～99% operability. The 280 K blackbody's photon irradiance was limited by an aperture and a band-pass filter from 3.6 μm to 3.8 μm resulting in a total flux of ～5×10(12) ph.cm(-2).s(-1). Under these low-light conditions, and consequently the use of a 13.5 ms integration time, the imager was observed to be BLIP thanks to a ～5 pA dark current from the 27 μm wide pixels. The total noise was dominated by the photon flux and read-out circuit which gave the imager a noise equivalent input of ～5×10(10) ph.cm(-2).s(-1) and temperature sensitivity of 9 mK with F/2.3 optics. Excellent imagery obtained using a 1-point correction alludes to the array's uniform responsivity.     

Application of piezoelectric actuation to regularize the chaotic response of an electrostatically actuated micro-beam

The impetus of this study is to investigate the nonlinear chaotic dynamics of a clamped–clamped micro-beam exposed to simultaneous electrostatic and piezoelectric actuation. The micro-beam is sandwiched with piezoelectric layers throughout its length. The combined DC and AC electrostatic actuation is imposed on the micro-beam through two upper and lower electrodes. The piezoelectric layers are actuated via a DC electric voltage applied in the direction of the height of the piezoelectric layers, which produces an axial force proportional to the applied DC voltage. The governing differential equation of the motion is derived using Hamiltonian principle and discretized to a nonlinear Duffing type ODE using Galerkin method. The governing ODE is numerically integrated to get the response of the system in terms of the governing parameters. The results show that the response of the system is greatly affected by the amounts of DC and AC electrostatic voltages applied to the upper and lower electrodes. The results show that the response of the system can be highly nonlinear and in some regions chaotic. Evaluating the K–S entropy of the system, based on several initial conditions given to the system, the chaotic response is distinguished from the periodic or quasiperiodic ones. The main objective is to passively control the chaotic response by applying an appropriate DC voltage to the piezoelectric layers.     

Linear frequency-doubling in dual Mid-IR-wavelength quantum cascade laser active region

In this paper we have proposed a novel quantum cascade laser active region design to obtain a dual-mid-IR-wavelength laser which is capable of frequency-doubling (13.77–6.88 μm) without utilizing nonlinear processes in two coupled shallow and deep quantum well structures. Optimized design of the active region leads to higher dipole matrix elements and thus higher laser performances. This method can be used to design laser structures with different frequency ratios.     

Determination of 4‐Nitrobenzaldehyde in Water Samples by Combination of Switchable Solvent Based Microextraction and Electrochemical Detection on MWCNTs Modified Electrode

A novel approach is presented to determine 4‐nitrobenzaldehyde in water samples. The procedure is based on switchable solvent based liquid‐liquid microextraction (SS‐LLME) and then determination by differential pulse voltammetry at multi‐walled carbon nanotubes modified glassy carbon electrode. Dipropylamine, a solvent with switchable polarity, was used as an extraction solvent that can be miscible/immiscible upon the changes of pH of sample solution. Effects of experimental conditions on SS‐LLME were investigated using a one‐factor‐at‐a‐time methodology. Under optimized conditions, a calibration curve was linear in the concentration range of 1.0 and 350 μg L^?1. Limits of quantification and detection were empirically 1.0 μg L^?1 and 0.3 μg L^?1, respectively. Intraday and Interday RSDs%, calculated in three concentration levels, were in the range of 6.2–7.8 % confirm the proper precision of the method. Finally, the performance of the method was evaluated successfully in real samples including drinking water, tap water and river water.     

Upgrading the Iranian national laboratory standard to conform to ISO 15189:2012

Accreditation and Quality Assurance - The Reference Health Laboratory (RHL) of Iran is the national authority responsible for making policies and plans for providing quality laboratory services...     

Hamiltonian Ratchets with Ultra‐Cold Atoms

Quantum‐resonance ratchets have been realized over the last ten years for the production of directed currents of atoms. These non‐dissipative systems are based on the interaction of a Bose‐Einstein condensate with an optical standing wave potential to produce a current of atoms in momentum space. In this paper we provide a review of the important features of these ratchets with a particular emphasis on their optimization using more complex initial states. We also examine their stability close to resonance conditions of the kicking. Finally we discuss the way in which these ratchets may pave the way for applications in quantum (random) walks and matter‐wave interferometry.     

A palladium complex immobilized onto mesoporous silica: a highly efficient and reusable catalytic system for carbon–carbon bond formation and anilines synthesis

A palladium complex supported on functionalized mesoporous silica MCM-41 proved to be a highly efficient, recoverable catalyst for C–C coupling reactions and amination of aryl halides to afford anilines. The nanocatalyst was characterized by FT-IR spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis, N₂ adsorption–desorption isotherms and inductively coupled plasma analysis. The catalyst could be reused for several consecutive runs without significant loss of activity. The excellent yields of products, simple reaction procedures and short reaction times are the main advantages of this methodology.     

Determination of carbamazepine in formulation samples using dispersive liquid–liquid microextraction method followed by ion mobility spectrometry

A simple, sensitive, fast and efficient method based on dispersive liquid–liquid microextraction (DLLME) followed by ion mobility spectrometry (IMS) has been proposed for preconcentration and trace detection of carbamazepine (CBZ) in formulation samples. In this method, 1 mL of methanol (disperser solvent) containing 80 μL of chloroform (extraction solvent) was rapidly injected by a syringe into a sample. After 5 min centrifugation, the preconcentrated carbamazepine in the organic phase was determined by IMS. Development of DLLME procedure includes optimization of parameters influencing the extraction efficiencies such as kind and volume of extraction solvent, disperser solvent and salt addition, centrifugation time and pH of the sample solution. The proposed method presented good linearity in the range of 0.05–10 μg mL^?1 and the detection limit was 0.025 μg mL^?1. The repeatability of the method expressed as relative standard deviation was 6 % (n = 5). This method has been applied to the analysis of carbamazepine formulation samples with satisfactory relative recoveries ≤75 %.