Synthesis,structure and biological activity of four new picolinohydrazonamide derivatives

Four new picolinohydrazonamide derivatives, namely, 6‐methyl‐N′‐(morpholine‐4‐carbonothioyl)picolinohydrazonamide, C₁₂H₁₇N₅OS, 6‐chloro‐N′‐(morpholine‐4‐carbonothioyl)picolinohydrazonamide methanol monosolvate, C₁₁H₁₄ClN₅OS·CH₃OH, 6‐chloro‐N′‐(4‐phenylpiperazine‐1‐carbonothioyl)picolinohydrazonamide, C₁₇H₁₉ClN₆S, and 6‐chloropicolinohydrazonamide, C₆H₇ClN₄, have been synthesized and characterized by NMR spectroscopy and single‐crystal low‐temperature X‐ray diffraction. In addition, their antibacterial and anti‐yeast activities have been determined. The first three compounds adopt the zwitterionic form in the crystal structure regardless of the presence or absence of solvent molecules in the structure. They also adopt the same symmetry, i.e. P2₁/c (P2₁/n), unlike the fourth structure which is chiral and has the space group P2₁2₁2₁. For all the studied cases, intermolecular N—H…O and N—H…N hydrogen bonds play an essential role in the formation of the structures.     

“What Doesn’t Kill You Makes You Stronger”: Future Applications of Amyloid Aggregates in Biomedicine

Amyloid proteins are linked to the pathogenesis of several diseases including Alzheimer’s disease, but at the same time a range of functional amyloids are physiologically important in humans. Although the disease pathogenies have been associated with protein aggregation, the mechanisms and factors that lead to protein aggregation are not completely understood. Paradoxically, unique characteristics of amyloids provide new opportunities for engineering innovative materials with biomedical applications. In this review, we discuss not only outstanding advances in biomedical applications of amyloid peptides, but also the mechanism of amyloid aggregation, factors affecting the process, and core sequences driving the aggregation. We aim with this review to provide a useful manual for those who engineer amyloids for innovative medicine solutions.     

Stannylation of unsaturated carbon-carbon bonds by tin tetrachloride

The reactions of tin tetrachloride and four terminal alkynes (PhCCH, ^tBuCCH, ⁿBuCCH, HOCH₂CCH), norbornene, and norbornadiene in dichloromethane or chloroform solution lead to the formation of stannylation products, which were characterized by ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy. Virtually complete α-regioselectivity was obtained in reaction of all four alkynes without any effect of the relative steric bulk of the substituent R at the triple bond of alkyne RC_βC_αH. The reaction of norbornene and norbornadiene with SnCl₄ is stereoselective, giving an exo stannylation product.     

The influence of crystalline structure of cellulose in chitosan-based biocomposites on removal of Ca(II), Mg(II), Fe(III) ion in aqueous solutions

Cellulose - In this work, the influence of the supermolecular structure of cellulosic fillers in chitosan matrix on the process of adsorption of calcium, magnesium and iron metal ion was analyzed,...     

Photopolymer diffractive optical elements in electronic speckle pattern shearing interferometry

In this paper we present an electronic speckle pattern shearing interferometer using a photopolymer diffractive optical element in the form of a holographic grating, in combination with a ground glass to shear the images. The sheared images on the ground glass are further imaged onto a CCD camera. The distance between the grating and the ground glass can be used to control the shear and to vary the sensitivity of the system. The direction of sensitivity is easily controlled by rotation of the diffraction grating around its normal.Introducing photopolymer holographic gratings in ESPSI gives the advantage of using high aperture optical elements at relatively low cost. The fact that the diffractive optical element is a photopolymer layer on glass substrate with thickness of 2 mm makes for a compact optical system.The system was successfully used for detection of the resonant frequencies of a vibrating object.Most of the published work on vibration analysis is analytical. Very few experimental results are available in the literature. The well known laser Doppler vibrometers (LDV) and accelerometers used for modal analysis are pointwise measurement techniques, although multipoint LDV is available at significant cost.Electronic speckle pattern techniques suitable for experimental detection of the resonant frequencies of vibrating objects are very promising for vibration analysis because they are whole field and non-contact.A finite element model is developed for prediction of the vibration modes of the object under test. Detection of vibrational modes of aluminium diaphragm is demonstrated and compared with the theoretical model. The results obtained are very promising for future application of ESPSI systems with HOEs, for modal analysis. A significant advantage of shearography over electronic speckle pattern interferometry is that ESPSI is relatively insensitive to external disturbances. Another advantage of the proposed system is that it could be easily converted to a phase-shifting electronic speckle shearing interferometer.     

Electronic structure and oxygen vacancies in PdO and ZnO: validation of DFT models

PdO is one of the most important catalytic materials currently used in the industry. In redox catalytic reactions involving PdO, the bulk phase is an additional source of oxygen. This leads to strong transformations not only at the surface of PdO but also in the near sub-surface and bulk regions. The redox process is, therefore, governed not only by the extent of PdO d-band filling, but also depends on the material properties of the PdO crystal--the ease with which its structure can be deformed. Methane oxidation is of key industrial interest, and therein the rate of CH(4) conversion depends strongly on the reversible oxygen defects formation on the surface and in the bulk of the catalyst. The present study gives a first insight into these complex phenomena at the atomistic level. Comparison of different density functional theory (DFT) approaches and their capacity to reproduce experimental values of the heat of formation as well as the band gap of the PdO are discussed in detail. Results from DFT calculations for an oxygen vacancy creation in the bulk and on the surface of PdO are presented and compared at the level of accuracy of the implemented approaches with defect calculations for ZnO. Many different modeling approaches based on functionals and pseudopotentials (non-modified PP and empirically tuned) have been evaluated in their aptness to capture key PdO properties. It was shown that simulations with the PP-115 pseudopotential gave the closest possible agreement to the relevant PdO thermodynamic data and energy of oxygen vacancy formation.     

Diffusion thermopower of (Ga,Mn)As/GaAs tunnel junctions

We report the observation of tunneling anisotropic magnetothermopower, a voltage response to a temperature difference across an interface between a normal and a magnetic semiconductor. The resulting voltage is related to the energy derivative of the density of states in the magnetic material, and thus has a strongly anisotropic response to the direction of magnetization in the material. The effect will have relevance to the operation of semiconductor spintronic devices, and may indeed already play a role in correctly interpreting the details of some earlier spin injection studies.     

Efficient image projection by Fourier electroholography

An improved efficient projection of color images is presented. It uses a phase spatial light modulator with three iteratively optimized Fourier holograms displayed simultaneously--each for one primary color. This spatial division instead of time division provides stable images. A pixelated structure of the modulator and fluctuations of liquid crystal molecules cause a zeroth-order peak, eliminated by additional wavelength-dependent phase factors shifting it before the image plane, where it is blocked with a matched filter. Speckles are suppressed by time integration of variable speckle patterns generated by additional randomizations of an initial phase and minor changes of the signal.