Spectral priors improve near-infrared diffuse tomography more than spatial priors

We compare the benefits of spatial and spectral priors in near-infrared diffuse tomography image reconstruction. Although previous studies that incorporated anatomical spatial priors have shown improvement in algorithm convergence and resolution, our results indicate that functional parameter quantification by this approach can be suboptimal. The incorporation of a priori spectral information significantly improves the accuracy observed in recovered images. Specifically, phantom results show that the maximum total hemoglobin concentration ([Hb(T)]) in a region of heterogeneity reached 91% of the true value compared to 63% using spatial priors. The combination of both priors produced results accurate to 98% of the true [Hb(T)]. When both spatial and spectral priors were applied in a healthy volunteer, glandular tissue showed a higher [Hb(T)], water fraction, and scattering power compared to adipose tissue.     

Intensified electrochemical hydrogen storage capacity of multi-walled carbon nanotubes supported with Ni nanoparticles

The electrochemical hydrogen storage properties of Ni-supported multi-walled carbon nanotube (Ni/MWCNT) electrodes were investigated using charge/discharge (C&D) and cyclic voltammetry (CV) techniques. Nickel NPs were deposited on the MWCNT surface, which was first chemically oxidized by H₂SO₄ and HNO₃ (3:1, v/v). Hydrogen storage was carried out by using the Ni/MWCNT electrode as the working electrode in the electrochemical cell. A set of various current densities were applied to the cell to produce (C&D) cycles, and it became optimum corresponding to 1.5 mA current. According to the electrochemical test results, the highest electrochemical discharge capacity of 1625 mAh g^?1 was obtained for the electrode with ratio of 4:1 (MWCNTs to Ni) in the initial cycle, which corresponded to 6.07 wt% H₂. The storage capacity was increased and reached to 4909 mAh g^?1 (18.34 wt% H₂) after 20 cycles, and the electrode maintained the specific capacity as cycling continued. Thus, the Ni/MWCNT electrode displays an excellent cycle stability and a high capacity reversibility. CV measurements also showed that the electrochemical adsorption and desorption amount of hydrogen was increased by Ni loading onto the CNTs and indicated that the electrochemical hydrogen adsorption of the electrode has an activated period.     

A new colorimetric assay for amylase based on starch-supported Cu/Au nanocluster peroxidase-like activity

In this paper, we present a new colorimetric technique as a novel assay for the easy and direct detection of α-amylase activity. This detection system utilizes the interaction of α-amylase with starch that is supporting copper/gold (Cu/Au) nanoclusters. The Cu/Au nanoclusters are synthesized using starch as a stabilizing agent at room temperature. These nanoclusters show robust peroxidase-like activity and are able to catalyze the oxidation of TMB (3,3,5,5-tetramethylbenzidine) in the presence of hydrogen peroxide (H₂O₂), leading to the generation of a blue-colored solution. The α-amylase detection mechanism is based on the digestion of the starch by α-amylase, which results in nanocluster aggregation, leading to increased nanoparticle size and thus decreased peroxidase-like activity of the Cu/Au NCs. Experiments showed that the gradual addition of α-amylase causes the peroxidase activity to decrease step by step in a linear fashion. Using this method, colorimetric sensing of α-amylase was achieved with a detection limit (LOD) of 0.04 U/mL and a linear range of 0.1–10 U/mL. This method is significantly selective for α-amylase and could be affordably and conveniently applied to the detection of α-amylase in blood serum.

Graphical Abstract

     

[2+2]-Photocycloaddition of 2-Morpholinopropenenitrile to Monosubstituted Benzils

Summary. Triplet excited unsymmetrically substituted benzils react with 2-morpholinopropenenitrile to form oxetanes. Whereas the selectivity with respect to the site of addition (benzoyl vs. 4-substituted benzoyl) is generally low, the photoadditions observed are all unidirectional (regioselective) and of high stereoselectivity, as had also been found earlier for benzil itself and for symmetrically 4,4-disubstituted benzils. The relative configurations of two oxetanes have been unambiguously confirmed by single crystal X-ray structure determinations.     

Electro-optical Kerr effect of azo-dye-doped liquid crystals using nulled intensity method

ABSTRACT

The electro-optical Kerr effect and pre-transition behavior have been investigated for different concentration of dimethyl-aminoazobenzene dye-doped nematic liquid crystal by using the nulled intensity method. Measurement results have showed that the molecular reorientation of liquid crystals induced by photoisomerization of azo dyes come about to increase an amount of Kerr constant at low percentages of dye concentration. Additionally, the results of pre-transition temperature which were obtained by extrapolating the invers Kerr constant as a function of temperature have been found to be in good agreement with predictions of the Landau-De Gennes model.     

Effect of the substitutional groups on the electrochemistry,kinetic of thermal decomposition and kinetic of substitution of some uranyl Schiff base complexes

Uranyl(VI) complexes, [UO₂(X-saloph)(solvent)], where saloph denotes N,N’-bis(salicylidene)-1,2-phenylenediamine and X = NO₂, Cl, Me, H; were synthesized and characterized by ¹H NMR, IR, UV–Vis spectroscopy, thermal gravimetry (TG), cyclic voltammetry, elemental analysis (C.H.N) and X-ray crystallography. X-ray crystallography of [UO₂(4-nitro-saloph)(DMF)] revealed coordination of the uranyl by the tetradentate Schiff base ligand and one solvent molecule, resulting in seven-coordinated uranium. The complex of [UO₂(4-nitro-saloph)(DMF)] was also synthesized in nano form. Transmission electron microscopy image showed nano-particles with sizes between 30 and 35 nm. The TG method and analysis of Coats-Redfern plots revealed that the kinetics of thermal decomposition of the complexes is of the first-order in all stages. The kinetics and mechanism of the exchange reaction of the coordinated solvent with tributylphosphine was investigated by spectrophotometric method. The second-order rate constants at four temperatures and the activation parameters showed an associative mechanism for all corresponding complexes with the following trend: 4-Nitro > 4-Cl > H > 4-Me. It was concluded that the steric and electronic properties of the complexes were important for the reaction rate. For analysis of anticancer properties of uranyl Schiff base complexes, cell culture and MTT assay was carried out. These results showed a reduction of jurkat cell line concentration across the complexes.     

Novel sitting-atop complexation between uranyl and meso-tetraarylporphyrins under mild conditions

We have investigated the effect of uranyl nitrate hexahydrate on free base meso-tetraarylporphyrins under mild conditions, at room temperature and containing a few drops of chloroform. The characterization of the products by ¹H NMR, IR and UV–Vis spectroscopy, elemental analysis and electrical conductometry demonstrated sitting-atop complex structures. The sitting-atop complexes are metalloporphyrins in which the metal ion is bonded to fewer than four nitrogen atoms in the distorted porphyrin plane. Such complexes may be considered as models for the initial steps of metallation of the macrocycles. This attempt is the first report of the preparation of sitting-atop complexes for actinides.     

Size dependent surface energy of nanoplates: Molecular dynamics and nanoscale continuum theory correlations

A nanoscale gradient continuum theory along with molecular dynamics simulations are employed to investigate the size-dependent surface energy of nanoplates. Molecular dynamics simulations reveal that upon nanoplate thickness reduction, the redistribution of surface energy density along thickness direction causes the decrease of the surface energy of nanoplate free surfaces. Via introducing a calibration benchmark, the length scale model parameter of the gradient continuum theory is methodically determined. The calibrated continuum theory is shown to well predict the size-dependent surface energy and the associated redistribution of surface energy density within nanoplates.     

Taub–NUT black holes in third order Lovelock gravity

We consider the existence of Taub–NUT solutions in third order Lovelock gravity with cosmological constant, and obtain the general form of these solutions in eight dimensions. We find that, as in the case of Gauss–Bonnet gravity and in contrast with the Taub–NUT solutions of Einstein gravity, the metric function depends on the specific form of the base factors on which one constructs the circle fibration. Thus, one may say that the independence of the NUT solutions on the geometry of the base space is not a robust feature of all generally covariant theories of gravity and is peculiar to Einstein gravity. We find that when Einstein gravity admits non-extremal NUT solutions with no curvature singularity at r=N$r=N$, then there exists a non-extremal NUT solution in third order Lovelock gravity. In 8-dimensional spacetime, this happens when the metric of the base space is chosen to be CP³${\mathbb{CP}}^3$. Indeed, third order Lovelock gravity does not admit non-extreme NUT solutions with any other base space. This is another property which is peculiar to Einstein gravity. We also find that the third order Lovelock gravity admits extremal NUT solution when the base space is T²×T²×T²$T^2\times T^2\times T^2$ or S²×T²×T²$S^2\times T^2\times T^2$. We have extended these observations to two conjectures about the existence of NUT solutions in Lovelock gravity in any even-dimensional spacetime.     

Palladium particles from oxime-derived palladacycle supported on Fe3O4/oleic acid as a catalyst forthe copper-free Sonogashira cross-coupling reaction

An oxime-derived palladacycle was synthesized using4-bromobenzoxime and pyridine in CHCl3, and characterized by FT-IR and1H NMR spectroscopy. This Pd complex was supported on Fe3O4/oleic acid and shown to be an efficient catalyst for the copper-free Sonogashira cross-coupling reaction of various aryl halides with phenylacetylene in air and in ethanol or mixed aqueous medium. The oxime-derived palladacycle gave highly active palladium nanoparticles for the organicsynthesis. The coupling products were obtained in high yields with low Pd loading and theheterogeneous catalyst can be separated by an external magnet andreused six times without loss of its activity. The characterization of the catalyst wascarried out by XRD, SEM and TEM. Both TEM and XRD revealed that the palladium nanoparticles were well dispersed with diameters from 5 to 10 nm and average size 9.97 nm.