On unitary analogs of GCD reciprocal LCM matrices

A divisor d ∈ ?₊ of n ∈ ?₊ is said to be a unitary divisor of n if (d, n/d) = 1. In this article we examine the greatest common unitary divisor (GCUD) reciprocal least common unitary multiple (LCUM) matrices. At first we concentrate on the difficulty of the non-existence of the LCUM and we present three different ways to overcome this difficulty. After that we calculate the determinant of the three GCUD reciprocal LCUM matrices with respect to certain types of functions arising from the LCUM problematics. We also analyse these classes of functions, which may be referred to as unitary analogs of the class of semimultiplicative functions, and find their connections to rational arithmetical functions. Our study shows that it does make a difference how to extend the concept of LCUM.     

X-ray diffraction study of molybdenum diselenide to 35.9 GPa

In situ high-pressure angle dispersive synchrotron X-ray diffraction studies of molybdenum diselenide (MoSe₂) were carried out in a diamond-anvil cell to 35.9 GPa. No evidence of a phase transformation was observed in the pressure range. By fitting the pressure-volume data to the third-order Birch-Murnaghan equation of state, the bulk modulus, K_0T, was determined to be 45.7±0.3 GPa with its pressure derivative, K′_0T, being 11.6±0.1. It was found that the c-axis decreased linearly with pressure at a slope of −0.1593 when pressures were lower than 10 GPa. It showed different linear decrease with the slope of a −0.0236 at pressures higher than 10 GPa.     

Diffusion-weighted imaging features of brain in obesity

PURPOSE: Obesity is characterized by an altered distribution of body fluid. However, distribution of fluid (extracellular/intracellular) in brain tissues has not been studied in obese subjects yet. The purpose of this study was to detect possible brain diffusion changes especially in satiety and hunger related centers in obese subjects by diffusion weighted imaging (DWI). METHODS: Conventional MRI and DWI of the brain was obtained from 81 obese patients (obese=68, morbid obese=13) and 29 age-matched, nonobese. The apparent diffusion coefficient (ADC) values were calculated in hypothalamus; amygdala; hippocampal gyrus; thalamus; insula; cingulate gyrus; orbitofrontal, dorsomedial and dorsolateral frontal, middle temporal and occipital cortex; cerebellum; midbrain and corpus striatum. RESULTS: The ADC values of hypothalamus, hippocampal gyrus, amygdala, insula, cerebellum and midbrain were significantly increased in patients (n:81) when compared to nonobese subjects. The ADC values of thalamus, hippocampal gyrus, amygdala, orbitofrontal, occipital, dorsolateral and middle temporal cortex, insula and midbrain were significantly increased in morbid obese when compared to nonobese subjects. The ADC values of orbitofrontal and occipital cortex were significantly higher in morbid obese than the values in the obese. The body mass index positively correlated with ADC values of amygdala, insula, orbitofrontal and middle temporal cortex. CONCLUSION: We observed increased ADC values of distinct locations related to satiety and hunger that suggest altered fluid distribution and/or vasogenic edema in obese subjects. Awareness of this abnormalities in brain tissue composition/function in obesity may contribute to better understanding of the underlying mechanisms.     

Effect of Operating Conditions in Production of Diagnostic Salmonella Enteritidis O-Antigen-Specific Monoclonal Antibody in Different Bioreactor Systems

In this study, different cultivation systems such as roller bottles (RB), 5-L stirred-tank bioreactor (STR), and disposable bioreactors were used to cultivate hybridoma for lab-scale production of Salmonella Enteritidis O-antigen-specific monoclonal antibody (MAb). Hybridoma cell line was cultivated in either serum-containing or serum-free medium (SFM) culture conditions. In STR, MAb production scaled up to 4 L, and production capabilities of the cells were also evaluated in different featured production systems. Moreover, the growth parameters of the cells in all production systems such as glucose consumption, lactate and ammonia production, and also MAb productivities were determined. Collected supernatants from the reactors were concentrated by a cross-flow filtration system. In conclusion, cells were not adapted to SFM in RB and STR. Therefore, less MAb titer in both STR and RB systems with SFM was observed compared to the cultures containing fetal bovine serum-supplemented medium. A higher MAb titer was gained in the membrane-aerated system compared to those in STR and RB. Although the highest MAb titer was obtained in the static membrane bioreactor system, the highest productivity was obtained in STR operated in semicontinuous mode with overlay aeration.     

Design of a tuned vibration absorber for a slender hollow cylindrical structure

Abstract

In this paper, details of the design work for a tuned vibration absorber to be used on a hollow cylindrical structure is presented. The vibration problem is of resonant type and the tuned vibration absorber is designed to suppress the displacement vibration response of the free end of the slender hollow structure dominated by the contribution of its lowest transverse vibration modes. The structure is modeled using a commercial finite element software. Finite element model of the structure is verified using experimentally obtained frequency response functions and modal parameters. Effective parameters of the tuned vibration absorber design are then determined based on finite element analysis simulations of the vibration suppression performance of the tuned vibration absorber as it is used on the structure. Details of the tuned vibration absorber design are determined and a prototype is fabricated. Prototype tuned vibration absorber is then characterized experimentally both as a standalone system and also as it is used on the main structure. Vibration reduction performance of the physical prototype of the tuned vibration absorber is also compared with its vibration reduction performance estimated from finite element analysis simulations so that the analysis based design process can be validated.

Communicated by Dumitru Caruntu.     

Highly enantioselective [4 + 2] cycloaddition reactions catalyzed by a chiral N-methyl-oxazaborolidinium cation

The reaction of lithium aryl borohydrides with salts of beta-amino alcohols provides a new route for the synthesis of oxazaborolidines. This method also leads to the first synthesis of hitherto elusive N-methyl oxazaborolidine cations, specifically the cationic proline derivative 3. Compound 3 is a strong chiral Lewis acid which is very effective for catalysis of [4 + 2]-cycloaddition reactions in good yield and with high enantioselectivity. Several diverse examples illustrate the scope of these catalytic reactions.     

An Electrochemical Sensor Fabricated by Sonochemical Approach for Determination of the Antipsychotic Drug Haloperidol

A nanocomposite (Ho₂O₃NPs/BNT) was synthesized by decorating holmium(III)oxide nanoparticles (H₂O₃NPs) on bentonite (BNT) through a realizable sonochemical approach for the electrochemical detection of haloperidol (Hlp). A glassy carbon electrode was modified with this nanocomposite. The Ho₂O₃NPs/BNT modified electrode outperformed bare and other modified electrodes in terms of electrochemical performance for Hlp detection in a pH 8.0 phosphate buffer. The proposed electrochemical platform showed a wide linear range (0.01 μM–24 μM), low detection limit (2.4 nM), and high sensitivity by square wave voltammetry. In addition, the proposed electrochemical sensor met the clinical criteria in terms of stability, selectivity, and repeatability.     

Electrochemical sensors for the simultaneous determination of zinc,cadmium and lead using a Nafion/ionic liquid/graphene composite modified screen-printed carbon electrode

A simple, low cost, and highly sensitive electrochemical sensor, based on a Nafion/ionic liquid/graphene composite modified screen-printed carbon electrode (N/IL/G/SPCE) was developed to determine zinc (Zn(II)), cadmium (Cd(II)), and lead (Pb(II)) simultaneously. This disposable electrode shows excellent conductivity and fast electron transfer kinetics. By in situ plating with a bismuth film (BiF), the developed electrode exhibited well-defined and separate peaks for Zn(II), Cd(II), and Pb(II) by square wave anodic stripping voltammetry (SWASV). Analytical characteristics of the BiF/N/IL/G/SPCE were explored with calibration curves which were found to be linear for Zn(II), Cd(II), and Pb(II) concentrations over the range from 0.1 to 100.0 ng L⁻¹. With an accumulation period of 120 s detection limits of 0.09 ng mL⁻¹, 0.06 ng L⁻¹ and 0.08 ng L⁻¹ were obtained for Zn(II), Cd(II) and Pb(II), respectively using the BiF/N/IL/G/SPCE sensor, calculated as 3σ value of the blank. In addition, the developed electrode displayed a good repeatability and reproducibility. The interference from other common ions associated with Zn(II), Cd(II) and Pb(II) detection could be effectively avoided. Finally, the proposed analytical procedure was applied to detect the trace metal ions in drinking water samples with satisfactory results which demonstrates the suitability of the BiF/N/IL/G/SPCE to detect heavy metals in water samples and the results agreed well with those obtained by inductively coupled plasma mass spectrometry.