Random solutions to a system of fractional differential equations via the Hadamard fractional derivative

In this work, we use a new random fixed point theorem in vector metric spaces due to Sinacer et al. [M.L. Sinacer et al., Random Oper. Stoch. Equ. 24, 93 (2016)] to prove the existence of solutions and the compactness of solution sets of a random system of fractional differential equations via the Hadamard-type derivative. The existence, modification and stochastically continuity of an M²-solution are also proved.     

Improvement of the Solubilization and Extraction of Curcumin in an Edible Ternary Solvent Mixture

A water-free, ternary solvent mixture consisting of a natural deep eutectic solvent (NADES), ethanol, and triacetin was investigated concerning its ability to dissolve and extract curcumin from Curcuma longa L. To this purpose, 11 NADES based on choline chloride, acetylcholine, and proline were screened using UV–vis measurements. A ternary phase diagram with a particularly promising NADES, based on choline chloride and levulinic acid was recorded and the solubility domains of the monophasic region were examined and correlated with the system’s structuring via light scattering experiments. At the optimum composition, close to the critical point, the solubility of curcumin could be enhanced by a factor of >1.5 with respect to acetone. In extraction experiments, conducted at the points of highest solubility and evaluated via HPLC, a total yield of ~84% curcuminoids per rhizome could be reached. Through multiple extraction cycles, reusing the extraction solvent, an enrichment of curcuminoids could be achieved while altering the solution. When counteracting the solvent change, even higher concentrated extracts can be obtained.     

Conducting Redoxpolymer-Based Reagentless Biosensors Using Modified PQQ-Dependent Glucose Dehydrogenase

Reagentless, oxygen-independent glucose biosensors based on an Os-complex-modified polypyrrole matrix and on soluble PQQ-dependent glucose dehydrogenase from Acinetobacter calcoaceticus are described.As the soluble form of glucose dehydrogenase from Acinetobacter calcoaceticus is a hydrophilic enzyme with a positive net charge, its entrapment into the positively charged hydrophobic polypyrrole film is much more complicated than that of the corresponding membrane enzyme or the negatively charged and very stable glucose oxidase. Possible ways for using soluble PQQ-dependent glucose dehydrogenase in combination with conducting polymer films are seen in the modulation of the enzyme properties by covalent binding of suitable compounds to the protein shell together with the adjustment of the properties of the conducting polymer film. This can be done by neutralising the net charge of the protein and/or optimising the electron-transfer pathway between enzyme and electrode surface by covalent binding of suitable redox relays to the protein surface.In addition, methods for increasing the hydrophilicity of the polymer film, such as the co-entrapment of high-molecular weight hydrophilic additives and copolymerisation of hydrophilic pyrrole derivatives are presented. It is demonstrated that the replacement of the parent monomer pyrrole by a suitable hydrophilic pyrrole derivative facilitates the entrapment of the modified soluble PQQ-dependent glucose dehydrogenase into the Os-complex-modified polymer and hence allows for the development of reagentless biosensors.     

Covalent coupling of unsaturated compounds to thiol agrarose using γ-Radiation

Unsaturated compounds can be attached to thiol polymers by means of ?-radiation. By this method several agarose conjugates have been synthesized from thiol agarose gel and different ligand derivatives (testosterone, estradiol, 3-octenoic acid, and hexa-2,4-dienoic acid). The amount of fixed ligand is about 60-120 μmol/g of dried conjugate. The method described is a valuable complement to the currently available procedures for the preparation of adsorbents for affinity chromatography.     

Preparation and Structure of A Novel Ethanolamine-occluding Aluminoarsenate

An aluminoarsenate, Al2As2O3.EAN, denoted as AlAsO4-1 was synthesized from EAN(EAN= ethanolamine), pyroarsenic acid and aluminium-iso-propylate systems. The crystal structure of AlAsO4-1 was determined by single crystal X-ray diffraction method. The compound crystallizes in orthorhombic space group Pcab with the unit cell constants:0 = 8.781(3), 6=10.261(3), c=20. 433(11) A .V = 1840.9 A3, 2=8. The final R and Rw factors are 0. 0401 and 0. 0344, respectively. The framework of AlAsO4-1 contains two types of Al atoms. It is interesting that in the asymmetric unit one of two Al atoms is strictly 4-coordinated and the other is 6-coordinated. The three-dimensional framework is built of two-dimensional nets which consist of 4-membered rings and 8-membered rings. The biggest open channel in the framework runs along [100], in which EAN template is located. Arsenic atoms can function as a component element for construction of three-dimensional net with topological novelty.     

Synthesis of 2-aminoquinazolines from ortho-fluorobenzaldehydes

The reaction of guanidine carbonate with various ortho-fluorobenzaldehydes in N,N-diinethylacetamide was investigated as a potential route for preparing 2-aminoquinazolines. Eleven new 2-aminoquinazolines were elaborated in this manner in low to moderate yields. In general the best results were obtained with ortho-fluorobenzaldehydes possessing an electron withdrawing substituent at the other ortho position. Complex mixtures were obtained using 2-fluorobenzaldehyde, 2,5-difluorobenzaldehyde and 2-fluoro-5-methoxybenzaldehyde which were not resolved.     

Determination of ultratrace quantities of uranium by laser-induced fluorescence spectrometry

Uranium (1.5–12 ng l^?1) is co-precipitated with calcium fluoride, the precipitate is ignited in air, and the uranium fluorescence induced by a pulsed nitrogen laser is measured. The detection limit is 0.5 ng l^?1 uranium. Iron(III) and lead interfere seriously.     

Synthesis of 2-aminoquinazolines from ortho-fluoroketones

The reactions of ten ortho-fluoroketones with guanidine carbonate in N,N-dimethylacetamide were investigated as a new synthetic approach to 2-amino-4-alkyl- and 2-amino-4-arylquinazolines. The yields obtained ranged from low to moderate and were highly dependent upon the nature of the substituents on the reactant. Eight new quinazolines were elaborated in this study.