Solving interval linear least squares problems by PPS-methods

Numerical Algorithms - In our work, we consider the linear least squares problem for m × n-systems of linear equations Ax = b, m ≥ n, such that the matrix A and right-hand side vector b...     

Characterization of Approximate Solutions of Vector Optimization Problems with a Variable Order Structure

In this paper, we deal with approximate solutions in vector-optimization problems with respect to a variable order structure. In the case of exact solutions of a vector optimization problem, especially in the variable order case, authors use a cone or a pointed convex cone-valued map in order to describe the solution concepts but in this paper, we use a set-valued map and this map is not a (pointed convex) cone-valued map necessarily. We characterize these solution concepts by a general scalarization method by means of nonlinear functionals. In the last section, an extension of Ekeland’s variational principle for a vector optimization problem with a variable order structure is given.     

Reparametrization of the Relativistic Infinitely Extended Charged Particle Action

In this letter, relativistic infinitely extended particles formulated. Correct form of action with possibility of reparametrization obtained and effect of electric field considered. It may be one of the first step to re-introduce theory of every things given by Nakano and Hessaby many years ago.     

Phenylglycine racemization in Fmoc-based solid-phase peptide synthesis: Stereochemical stability is achieved by choice of reaction conditions

Phenylglycine-containing peptides have broad applications in medicinal chemistry, but their synthetic accessibility is complicated by the risk of epimerization during solid-phase peptide synthesis (SPPS). Phenylglycine is therefore often considered a troublesome residue. This work studies the extent of Phg racemization under different Fmoc-SPPS reaction conditions. It is shown that the base-catalyzed coupling of Fmoc-Phg is the critical step for racemization. However, racemization can be reduced to a negligible level if DEPBT or COMU combined with TMP or DMP are employed during this step. Resin-bound peptides are remarkably resistant against epimerization during extended incubation under basic conditions and the free peptides were stable in buffer solutions used for biological assays.     

Synthesis of aryl-substituted or aryl-fused N-hydroxyethyl and N-hydroxymethypyrazole derivatives as potential ligands for the estrogen receptor

A new series of N-hydroxyethylpyrazole (12a–f) and N-hydroxymethylpyrazole derivatives (15a–f) were designed for their estrogenic activities, having a 11.0 ± 0.5 Å distance between their two hydroxyl groups, aliphatic–OH and phenolic–OH similar to 17β-estradiol (E2) as an endogenous hormone. To synthesize the title compounds, the key intermediate 1,3-dicarbonyl derivatives (2 and 8), were treated with hydrazine hydrate to produce the pyrazole ring 5 and 9. Further hydroxyalkylation of the latter produced the title pyrazoles. The position of hydroxyethyl or hydroxymethyl substituents in the products was determined through 2D NOE NMR spectroscopy.     

Synthesis and characterization of silver/lithium cobalt oxide (Ag/LiCoO2) nanofibers via sol–gel electrospinning

We report on the preparation and characterization of Ag/LiCoO₂ nanofibers (NFs) via the sol–gel electrospinning (ES) technique. Ag nanoparticles (NPs) were produced in an aqueous polyvinyl pyrrolidone (PVP) solution by using AgNO₃ precursor. A viscous lithium acetate/cobalt acetate/polyvinylalcohol/water (LiAc/(CoAc)₂/PVA/water) solution was prepared separately. A Ag NPs/PVP/water solution was prepared and added to this viscous solution and magnetically stirred to obtain the final homogeneous electrospinning solution. After establishing the proper electrospinning conditions, as-spun precursor Ag/LiAc/Co(Ac)₂/PVA/PVP NFs were formed and calcined in air at a temperature of 600 °C for 3 h to form well-crystallized porous Ag/LiCoO₂ NFs. Various analytical characterization techniques such as UV–vis, SEM, TEM, TGA, XRD, and XPS were performed to analyze Ag NPs, as-spun and calcined NFs. It was established that Ag NPs in the precursor Ag/LiAc/Co(Ac)₂/PVA/PVP NFs are highly self-aligned as a result of the behavior of Ag in the electric field of the electrospinning setup and the interaction of Ag ions with Li and Co ions in the NF. Ag/LiCoO₂ NFs exhibit a nanoporous structure compared with un-doped LiCoO₂ NFs because the atomic radius of Ag is larger than the radius of Co and Li ion; thus, no substitution between Ag and Li or Ag and Co atoms occurs, and Ag NPs are located at the interlayer of LiCoO₂ while some are left in the fiber.     

Automatic segmentation of brain MRI in high-dimensional local and non-local feature space based on sparse representation

Automatic extraction of the varying regions of magnetic resonance images is required as a prior step in a diagnostic intelligent system. The sparsest representation and high-dimensional feature are provided based on learned dictionary. The classification is done by employing the technique that computes the reconstruction error locally and non-locally of each pixel. The acquired results from the real and simulated images are superior to the best MRI segmentation method with regard to the stability advantages. In addition, it is segmented exactly through a formula taken from the distance and sparse factors. Also, it is done automatically taking sparse factor in unsupervised clustering methods whose results have been improved.     

Reaction Between Isocyanides and Dialkyl Acetylenedicarboxylates in the Presence of Hydantoins – A One-pot Synthesis of Stable Ketenimines

Summary. The reactive 1:1 intermediate produced in the reaction between isocyanides and dialkyl acetylenedicarboxylates was trapped by hydantoins to yield highly functionalized stable ketenimines in fairly good yields.     

Calculating mass transfer from vertical wet fabrics using a free convection heat transfer correlation

In this note, the evaporation rate from a vertical wet fabric sheet is calculated using a free convection heat transfer correlation. Chilton–Colburn analogy is used to derive a mass transfer correlation from a heat transfer correlation proposed by Churchill and Chu for free convection from a vertical isothermal plate. The mass transfer rate obtained from this expression has shown excellent agreement with experimental data.     

Poly(aminohippuric acid)–sodium dodecyl sulfate/functionalized graphene oxide nanocomposite for amplified electrochemical sensing of gallic acid

Gallic acid (GA), as a main phenolic acid, has been considered the main player on the human health, including the effects of reduction of cholesterol, depression of hypertension, anti-oxidation, anti-microbial, protection against cardiovascular disease and cancer. This study describes the development, electrochemical characterization and utilization of a novel functionalized graphene oxide/poly(p-aminohippuric acid)–sodium dodecyl sulfate nanocomposite modified glassy carbon electrode (APTS@GO/PPAH-SDS/GCE) for the electrocatalytic determination of GA. The synthesized nanocomposite was characterized by different techniques such as Fourier-transform infrared spectroscopy, thermo-gravimetric analysis and transmission electron microscopy. The electrochemical oxidation of GA was investigated by cyclic voltammetry, differential pulse voltammetry and amperometry. The modified electrode showed a potent and persistent electron mediating behavior followed by well-defined oxidation peak of GA and the linear range of 0.006–2000 µmol L^?1 with a detection limit of 1.7 nmol L^?1 for GA (S/N?=?3) using amperometric method. Also, it was successfully used for the GA determination in the black tea and tab water as real samples. Additionally, this electrode exhibited good stability and reproducibility. The results imply that the APTS@GO/PPAH-SDS nanocomposite might be a promising candidate for practical applications in GA electrochemical detection.