New 5-methylisatin including thiocarbohydrazones: preparation,structure elucidation and antimicrobial activity

Research on Chemical Intermediates - New 5-methylisatin including thiocarbohydrazones (1–5) have been synthesized. The chemical structure of synthesized compounds was elucidated with IR, 1H...     

Worst-case robust decisions for multi-period mean–variance portfolio optimization

In this paper, we extend the multi-period mean–variance optimization framework to worst-case design with multiple rival return and risk scenarios. Our approach involves a min–max algorithm and a multi-period mean–variance optimization framework for the stochastic aspects of the scenario tree. Multi-period portfolio optimization entails the construction of a scenario tree representing a discretised estimate of uncertainties and associated probabilities in future stages. The expected value of the portfolio return is maximized simultaneously with the minimization of its variance. There are two sources of further uncertainty that might require a strengthening of the robustness of the decision. The first is that some rival uncertainty scenarios may be too critical to consider in terms of probabilities. The second is that the return variance estimate is usually inaccurate and there are different rival estimates, or scenarios. In either case, the best decision has the additional property that, in terms of risk and return, performance is guaranteed in view of all the rival scenarios. The ex-ante performance of min–max models is tested using historical data and backtesting results are presented.     

Characterization and Comparative Studies on Conventional and Microwave Synthesis of Some Disulfides

Abstract

Some disulfide derivatives have been prepared by microwave assisted synthesis methodology from thiophthalimides(sulfenimides) and thiols in a modified microwave oven under reflux at 600 Watt in ethanol. Elucidation of the structures of the synthesized compounds has been performed by IR, ¹H NMR, and ¹³C NMR spectroscopic methods.

[Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental files: Additional figures]     

Multivariate Count Data Models for Time Series Forecasting

Count data appears in many research fields and exhibits certain features that make modeling difficult. Most popular approaches to modeling count data can be classified into observation and parameter-driven models. In this paper, we review two models from these classes: the log-linear multivariate conditional intensity model (also referred to as an integer-valued generalized autoregressive conditional heteroskedastic model) and the non-linear state-space model for count data. We compare these models in terms of forecasting performance on simulated data and two real datasets. In simulations, we consider the case of model misspecification. We find that both models have advantages in different situations, and we discuss the pros and cons of inference for both models in detail.     

Hit-And-Run enables efficient weight generation for simulation-based multiple criteria decision analysis

Models for Multiple Criteria Decision Analysis (MCDA) often separate per-criterion attractiveness evaluation from weighted aggregation of these evaluations across the different criteria. In simulation-based MCDA methods, such as Stochastic Multicriteria Acceptability Analysis, uncertainty in the weights is modeled through a uniform distribution on the feasible weight space defined by a set of linear constraints. Efficient sampling methods have been proposed for special cases, such as the unconstrained weight space or complete ordering of the weights. However, no efficient methods are available for other constraints such as imprecise trade-off ratios, and specialized sampling methods do not allow for flexibility in combining the different constraint types. In this paper, we explore how the Hit-And-Run sampler can be applied as a general approach for sampling from the convex weight space that results from an arbitrary combination of linear weight constraints. We present a technique for transforming the weight space to enable application of Hit-And-Run, and evaluate the sampler’s efficiency through computational tests. Our results show that the thinning factor required to obtain uniform samples can be expressed as a function of the number of criteria n as φ(n) = (n − 1)³. We also find that the technique is reasonably fast with problem sizes encountered in practice and that autocorrelation is an appropriate convergence metric.     

Hybrid nanoflowers bearing tetraphenylporphyrin assembled on copper(II) or cobalt(II) inorganic material: A green efficient catalyst for hydrogenation of nitrobenzenes in water

Simple fabrication of organic–inorganic hybrid nanoflowers (TPP@CuhNfs and TPP@CohNfs) was achieved with tetraphenylporphyrin (TPP) as organic counterpart and Cu²⁺ or Co²⁺ ions as inorganic materials via a green route, with lower cost and controlled pH. The effect of pH levels and TPP concentrations on the morphology of the TPP@CuhNfs and TPP@CohNfs materials was examined by scanning electron microscopy (energy-dispersive X-ray [EDX]). The formation and chemical structures of TPP@CuhNfs and TPP@CohNfs were evaluated using Fourier transform infrared. Elemental analyses of these hybrid nanoflowers were carried out by EDX. The fabricated TPP@CuhNfs and TPP@CohNfs nanomaterials under optimum conditions act as effective reusable catalysts for the hydrogenation of nitroanilines in aqueous media at ambient temperature. The time-dependent hydrogenation can be easily monitored spectrophotometrically and verified by ¹H-nuclear magnetic resonance. These types of the catalytic reaction or system are recorded to be useful toward the hydrogenation of nitroanilines, regardless of the position and type of substrate. Moreover, TPP@CuhNfs and TPP@CohNfs catalysts demonstrated a type of metal ions-dependent catalytic efficiency toward hydrogenation of nitroanilines (organic pollutants), with TPP@CuhNfs found to be more effective than TPP@CohNfs. However, both catalysts containing Cu²⁺ and Co²⁺ ions showed good performance and can be reused at least five times without a significant decline in yield. The presented approach based on hybrid nanoflowers provides as a low cost and ecofriendly method (green route) for different catalytic hydrogenations.     

A Novel Fullerene‐Pyrrole‐Pyrrole‐3‐Carboxylic Acid Nanocomposite Modified Molecularly Imprinted Impedimetric Sensor for Dopamine Determination in Urine

In this study, we designed an electrochemical impedance based sensor by using molecularly imprinted fullerene modified pyrrole‐pyrrole‐3‐carboxylic acid copolymers on screen printed carbon electrode to monitor dopamine in real urine samples. All modifications were characterized by electrochemical impedance spectroscopy (EIS) and Scanning Electron Microscopy (SEM). Performance parameters of the developed sensor system were determined by calibration curve performed between 25 ng/mL and 250 ng/mL (R2= 0.9939). LOD and LOQ were 8.77 ng/mL and 26.6 ng/mL, respectively. The developed sensor method was compared with ELISA. The regression analysis between ELISA and the sensor analysis showed good correlation with R2= 0.979     

A new synthon for the synthesis of aminoinositol derivatives

The regio- and stereoselective synthesis of a new synthon, trans-3,8-dioxatricyclo[3.2.1.0^2,4]octane-6,7-diamine, from 7-oxabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate is reported. Transformation of the acid functionalities to acyl azides followed by Curtius rearrangement gave the corresponding trans-diisocyanate, which was reacted with HCl to produce a trans-diamino compound that is a potentially important synthon for the versatile synthesis of aminocyclitols.     

NOR expression increases in interphase lymphocytes of Down syndrome babies/children as AgNORs surface, according to the mitogen concentration in the culture medium

The extra chromosome 21 of Down syndrome (DS) or trisomy 21 patients contains an average of 40 extra copies of rRNA genes and the in vivo/in vitro regulation of the activity of these genes is not fully understood. The objective of this work was to compare the NORs expression pattern in interphase lymphocytes of DS patients with regular trisomy 21 and control individuals according to phytohemagglutinin (PHA) concentration (0.37, 0.75, 1.48 and 2.21 ml) per 100 ml of medium. Because the AgNOR staining is an indicator of the active rRNA genes, comparison of the image analysis values of the AgNOR area in 72 h cultivated lymphocytes for each concentration of PHA between DS patients (N=30) and controls (N=24) provided a plausible conclusion on the regulation of the extra rRNA genes in DS lymphocytes. The nucleolus organizer regions area/total nuclear area (NORa/TNa) was calculated using an in-house computer program. Fifty consecutive interphases per PHA concentration were analysed for each individual, for determination of the NORa/TNa. In contrast to healthy controls, NORa/TNa of lymphocytes from DS patient babies/children (0-8 years old) increased gradually in parallel with the PHA concentration in the culture medium: 10.44+/-1.72% for 0.37 ml of PHA, 11.74+/-1.93% for 0.75 ml of PHA, 13.25+/-2.03% for 1.48 ml of PHA and 13.43+/-2.08% for 2.21 ml of PHA per 100 ml of medium. Contrary to control cells (in which the NORa/TNa ratio according to PHA concentration in the culture medium remains constant), DS interphase lymphocytes in culture do not down-regulate their NOR expression. These results obtained from interphase NORs are consistent with the previous results obtained by evaluating the mean of AgNOR+ chromosome number in metaphase cells, also in relation to the mitogen concentration in the culture medium.