Analysis of microorganisms with nonlinear electrokinetic microsystems

Nonlinear electrokinetics (EK), specifically electrophoresis of the second kind, dielectrophoresis (DEP) and electrorotation (EROT), have gained significant interest recently for their flexibility and labeless discriminant manner of operation. The current applications of these technologies are a clear advancement from what they were when first discovered, but also still show strong signs of future growth. The present review article presents a discussion of the current uses of microscale nonlinear EK technologies as analytical, sensing, and purification tools for microorganisms. The discussion is focused on some of the latest discoveries with various nonlinear EK microfluidic techniques, such as DEP particle trapping and EROT for particle assessments, for the analysis of microorganisms ranging from viruses to parasites. Along the way, special focus was given to key research articles from within the past two years to provide the most up-to-date knowledge on the current state-of-the-art within the field of microscale EK, and from there, an outlook on where the future of the field is headed is also included.     

Propagation of Lamb waves in an immersed periodically grooved plate: Experimental detection of the scattered converted backward waves

Guided waves propagation in immersed plates with irregular surfaces has potential application to detection and assessment of the extent, depth and pattern of the irregularity. The complexity of the problem, due to the large number of involved parameters, has limited the number of existing studies. The simplest case of irregularities of practical interest is the two-dimensional corrosion profile. Even this case is in general so complex, that one can extract several amplitude dominant periodic surfaces only by using a Fourier spectrum of the surface. Guided waves in plates, with one or both free surfaces having periodic perturbations of different shapes, have been presented in specialized literature.     

Higher temperature order–disorder transition,electrical and optical properties of [N(C2H5)4]2Pd2Cl6 compound

[N(C₂H₅)₄]₂Pd₂Cl₆ hybrid compound with semiconducting character was synthetized and characterized by X-ray diffraction, the thermal, optical and electrical properties. X-ray diffraction indicates that the compound crystallize at room temperature in the orthorhombic system and (Immm) space group. Two endothermic peaks at, 343 K and 440 K were observed in the DSC measurements corresponding to the evaporation of water molecules and order-disorder transition, respectively. The optical band gap (E_g = 4.34 eV) was deduced by the Tauc relation. The electrical properties was studied using the impedance spectroscopy in the frequency range of 0.1 Hz to 1 MHz and over the temperature range of 270 K to 480 K. The analysis of Nyquist plots revealed the presence of grains, grain boundaries and the electrode effects. The equivalent circuit was determined. The Ac conductivity was analyzed by the Jonsher low and the conduction mechanism was deduced based in the Elliot theory and indicate that the correlated barrier hopping model (CBH) was described the two regions II and IV and the overlapping polaron model (OLPT) the right model described the conduction in the regions I and III.     

Optical and electrical properties and conduction mechanism of [(CH3)2NH2]2CoCl4

Monoclinic crystals of [(CH₃)₂NH₂]₂CoCl₄ are of the space group P2₁/n. Unit cell dimensions are as follows: a = 8.5393 Å, b = 11.3905 Å, c = 13.4069 Å and β = 91.02°. This compound undergoes several phase transitions. The optical properties were measured by means of UV–visible absorption spectroscopy in the range 200–800 nm. Analysis of the data revealed the existence of direct allowed optical transition mechanisms with bandgap energy equal to 3.84 eV. The electrical conductivity of [(CH₃)₂NH₂]₂CoCl₄ was studied in the frequency range 10⁻¹–10⁶ Hz and in the temperature range 411–449 K by means of impedance spectroscopy. Impedance and modulus analyses indicated temperature-independent distribution of relaxation times and non-Debye behavior in this material. A super-linear power law was observed for the AC conductivity, which was analyzed based on the jump relaxation model σ_ac = σ_dc + A₁ω^s1 + A₂ω^s2. Accordingly, the first AC term A₁ω^s1 corresponds to translational hopping motion and the second term A₂ω^s2 to well-localized hopping and/or reorientational motion. Conduction takes place via correlated barrier hopping in phases I and II.     

Tailoring of Polarizing Agents in the bTurea Series for Cross‐Effect Dynamic Nuclear Polarization in Aqueous Media

A series of 18 nitroxide biradicals derived from bTurea has been prepared, and their enhancement factors ? (¹H) in cross‐effect dynamic nuclear polarization (CE DNP) NMR experiments at 9.4 and 14.1 T and 100 K in a DNP‐optimized glycerol/water matrix (“DNP juice”) have been studied. We observe that ? (¹H) is strongly correlated with the substituents on the polarizing agents, and its trend is discussed in terms of different molecular parameters: solubility, average e–e distance, relative orientation of the nitroxide moieties, and electron spin relaxation times. We show that too short an e–e distance or too long a T_1e can dramatically limit ? (¹H). Our study also shows that the molecular structure of AMUPol is not optimal and its ? (¹H) could be further improved through stronger interaction with the glassy matrix and a better orientation of the TEMPO moieties. A new AMUPol derivative introduced here provides a better ? (¹H) than AMUPol itself (by a factor of ca. 1.2).     

A note on Hermite polynomials of several variables

The present paper deals with an extension of certain results obtained by Burchnall for Hermite polynomials to similar results for Hermite polynomials of several variables.     

Properties of amorphous carbon nitride prepared by RF reactive sputtering

The local microstructure and optical and electrical properties were investigated of amorphous carbon nitride (a-CN) films deposited by reactive radio-frequency (RF) sputtering. Two series prepared in nitrogen or in a nitrogen and argon mixture were studied. The optical properties were investigated by transmittance/reflectance and photothermal deflection spectroscopies. Combined infrared measurements and Raman scattering spectroscopies were used to investigate the microstructure of a-CN films in terms of nitrogen incorporation within the films and C sp ² content. These experiments were completed by dark electrical conductivity measurements performed in coplanar configuration in the temperature range 50–450?K. The films exhibit semiconductor behaviour and the temperature dependence suggests two types of conduction. An increase in nitrogen incorporation induces an increase with clustering of sp ² phase replacing C=C olefinic groups with aromatic groups.     

VCl3 catalyzed imine-based multicomponent reactions for the facile access of functionalized tetrahydropyridines and β-amino carbonyls

Abstract  

A simple, mild, and highly efficient method has been developed for the preparation of functionalized tetrahydropyridines and β-amino carbonyls from the multicomponent reactions involving in situ imines and vanadium (III) chloride as a Lewis acid. The multicomponent reaction of two equivalents of aromatic aldehyde, two equivalents of amine, and one equivalent β-keto ester in the presence of catalytic amount of VCl₃ provides highly atom economic five-component tetrahydropyridines in very good yields. The same catalyst was found useful for the efficient synthesis of a wide variety of β-amino ketones using direct-type Mannich reaction of aromatic aldehyde, amine, and aromatic ketones. The notable advantages of this method are simple procedure, short reaction time and good yields, and applicable to broad range of substrates.