Portable single-sided NMR measurements at variable temperatures: Implementation of a thermo-controlled device and application to the heating of bread dough

A temperature control unit was implemented to vary the temperature of samples studied on a commercial Mobile Universal Surface Explorer nuclear magnetic resonance (MOUSE-NMR) apparatus. The device was miniaturized to fit the maximum MOUSE sampling depth (25 mm). It was constituted by a sample holder sandwiched between two heat exchangers placed below and above the sample. Air was chosen as the fluid to control the temperature at the bottom of the sample, at the interface between the NMR probe and the sample holder, in order to gain space. The upper surface of the sample was regulated by the circulation of water inside a second heat exchanger placed above the sample holder. The feasibility of using such a device was demonstrated first on pure water and then on several samples of bread dough with different water contents. For this, T1 relaxation times were measured at various temperatures and depths and were then compared with those acquired with a conventional compact closed-magnet spectrometer. Discussion of results was based on biochemical transformations in bread dough (starch gelatinization and gluten heat denaturation). It was demonstrated that, within a certain water level range, and because of the low magnetic field strength of the MOUSE, a linear relationship could be established between T1 relaxation times and the local temperature in the dough sample.     

Thermal conductivity modeling of nanofluids with ZnO particles by using approaches based on artificial neural network and MARS

Journal of Thermal Analysis and Calorimetry - Nanofluids are attractive alternatives for the current heat transfer fluids due to their remarkably higher thermal conductivity which leads to the...     

Effect of pH on the electrochemical properties of polyaniline nanoparticle suspension in strongly acidic solution: an experimental and theoretical study

Journal of Solid State Electrochemistry - A stable suspension of nanopolyaniline (nPANI) particles can be used in various applications instead of a polyaniline film. The electrochemical behavior of...     

Modified lattice Boltzmann solution for non-isothermal rarefied gas flow through microchannel utilizing BSR and second-order implicit schemes

Journal of Thermal Analysis and Calorimetry - Thermal microscale gas flow was simulated into a coplanar microchannel was simulated at a broad range of Knudsen numbers. Attempts were made to improve...     

New suggestion for electronic structure of the ground state of ozone

Determination of electronic structure of ozone related geometry is the main subject in this research. The proposed electronic structure must satisfy the experimental geometry, explain the excellent oxidizing properties of ozone, and can also explain the capability of additional reaction with unsaturated hydrocarbons. The potential energy surface of singlet and triplet state of ozone has been studied in order to check the correctness of the proposed structure. The proposed electronic structure of ozone is capable of explaining the oxidizing behavior of ozone in visible wavelength (daylight) 430–700 nm. For comparison, the other proposed structure of ozone in literature such as Pauling, Linnett and Weinhold has also been discussed. The main method used in this research is well-known density functional procedure, B3LYP, which takes the electron correlation aspect into consideration. The polarization and diffused functions are included in the basis set, 6-311++G**. The obtained geometry is a bent and cumulated double bond with inter-bond angle 118.42° (1.39%), and bond length 1.256 Å (1.72%). The obtained results revealed that frontier orbital theory is a proper tool for explaining the addition reaction.     

Highly selective PVC-membrane electrodes based on Co(II)-Salen for determination of nitrite ion.

A cobalt(II) derivative was used as a suitable ionophore for the preparation of a polymeric membrane nitrite-selective electrode. The electrode reveals a Nemstian behavior over a very wide NO2- ion concentration range (1.0 x 10(-6)-1.0 x 10(-1) M) and a very low detection limit (5.0 x 10(-7) M). The potentiometric response is independent of the pH of solution in the pH range 4.0-9.5. The electrode shows advantages such as low resistance, fast response and, most importantly, good selectivity relative to a wide variety of inorganic and organic anions. In fact, the selectivity behavior of the proposed NO2- ion-selective electrode shows great improvements compared to the previously reported electrodes for nitrite ion. The proposed electrodes could be used for at least 2 months without any significant changes in potentials. The electrode was successfully applied to the determination of nitrate ion concentrations in sausage and milk samples.     

Iodine‐Catalyzed Friedlander Quinoline Synthesis under Solvent‐Free Conditions

Polyfunctional quinolines were synthesized using Friedlander method catalyzed by molecular iodine in high yields at 60 °C under solvent‐free conditions.     

Kinetic Spectrophotometric Determination of Trace Amounts of Nitrite by Catalytic Reaction between Methylthymol Blue and Bromate

A kinetic spectrophotometric method for determination of trace nitrite in two dynamic ranges (2–100 and 100–500 ng/mL) based on its catalytic effect on the reaction between methylthymol blue and potassium bromate in acidic (sulfuric acid) media is described. The reaction was monitored spectrophotometrically by measuring the decreasing color of methylthymol blue at 437 nm by the fixed‐time method of 4.0 min at 30°C. The detection limit is 0.6 ng/mL, and the relative standard deviations for 50.0 and 250.0 ng/mL nitrite are 1.6% and 1.3%, respectively. The method was used for the determination of nitrite in water samples.