Metal complexes of sulphur-nitrogen chelating agents. Part 14. Nickel(II), palladium(II), copper(II), cobalt(II), and cobalt(III) complexes of the tetradentate schiff bases having ONNS donor sites

Summary Complexes of nickel(II), palladium(II), copper(II), cobalt(II), and cobalt(III) with methyl-2-(-salicylaldiminoethyl)-cyclopent-1-en-dithiocarboxylate (H₂L¹) and methyl-2-(-salicylaldiminoisopropyl)cyclopent-1-en-dithiocarboxylate (H₂L²) have been prepared. They contain the donor sites ONNS. The metal(II) ions from neutral, monomeric square planar chelate complexes. The cobalt(III) complexes [CoL¹-(H₂O)₂]X (X=Cl or ClO₄) appear to betrans-diaqua-species. All compounds have been characterized by a number of physico-chemical methods.     

E.p.r. spectra and bonding parameters of copper(ii) complexes of 2-methyl-4,6-diacylphenols,of the dibenzoyl analogues and of some of their derivatives

Summary The e.p.r. spectra of mononuclear copper(II) complexes of 2-methyl-4,6-diacylphenols and dibenzoylphenols, and their condensation products with 1,3-diaminopropane have been examined. The MO coefficients evaluated from e.p.r. spectral parameters indicate that the in-plane-, in-plane- and out-of-plane- bondings are significantly covalent. The e.p.r. spectra of the macrocyclic dicopper(II) complexes derived from 2-methyl-4,6-diacyl(benzoyl)phenols and 1,3-diaminopropane measured at 77 K reveal the presence of mononuclear species of axial symmetry.     

Thermal noise in Hg0.795Cd0.205Te detectors for large biasing fields

Thermal noise in Hg_0.795Cd_0.205Te detectors is estimated for large biasing fields at a lattice temperature of 77 K, by computing the correlation functions of the velocity fluctuations with the Monte Carlo technique. The noise temperature for current components transverse to the field is almost independent of the field, but that corresponding to the parallel component increases by a factor of about 1.3 at 50 V/cm and by a factor of 3.0 at 300V/cm. The thermal noise voltage for a detector of 85 resistance increases from 0.6nV/Hz^1/2 at low biasing fields to about 3nV/Hz^1/2 at a field of 300 V/cm. The noise power is also found to remain constant up to about 75 GHz, and it decreases thereafter by a factor of 0.25 for doubling of the frequency.     

The k-essence scalar field in the context of Supernova Ia observations

We study a framework where the hypothesis of a minimum length in space-time is complemented with the notion of reference frame invariance. It turns out natural to interpret the action of the obtained reference frame transformations in the context of doubly special relativity. As a consequence of this formalism we find interesting connections between the minimum length properties and the modified velocity-energy relation for ultra-relativistic particles. For example, we can predict the ratio between the minimum lengths in space and time using the results from OPERA on superluminal neutrinos.     

H2-release from alcohols,diols, and compounds with amino functionality promoted by titanium(II) sandwich complex, [Cp2Ti]: a theoretical approach

Structural Chemistry - The role of Ti(II) sandwich complex, [Cp2Ti], generated by the combination of [Cp2TiCl2] and two equivalents of nBuLi, in situ, in toluene has been investigated theoretically...     

Artificial neural network‐based modeling of snow properties using field data and hyperspectral imagery

This study attempts to model snow wetness and snow density of Himalayan snow cover using a combination of Hyperspectral image processing and Artificial Neural Network (ANN). Initially, a total of 300 spectral signature measurements, synchronized with snow wetness and snow density, were collected in the field. The spectral reflectance of snow was then modeled as a function of snow properties using ANN. Four snow wetness and three snow density models were developed. A strong correlation was observed in near‐infrared and shortwave‐infrared region. The correlation analysis of ANN modeled snow density and snow wetness showed a strong linear relationship with field‐based data values ranging from 0.87–0.90 and 0.88–0.91, respectively. Our results indicate that an Artificial Intelligence (AI) approach, using a combination of Hyperspectral image processing and ANN, can be efficiently used to predict snow properties (wetness and density) in the Himalayan region. Recommendations for resource managers

• Snow properties, such as snow wetness and snow density are mainly investigated through field‐based survey but rugged terrains, difficult weather conditions, and logistics management issues establish remote sensing as an efficient alternative to monitor snow properties, especially in the mountain environment.
• Although Hyperspectral remote sensing is a powerful tool to conduct the quantitative analysis of the physical properties of snow, only a few studies have used hyperspectral data for the estimation of snow density and wetness in the Himalayan region. This could be because of the lack of synchronized snow properties data with field‐based spectral acquisitions.
• In combination with Hyperspectral image processing, Artificial Neural Network (ANN) can be a useful tool for effective snow modeling because of its ability to capture and represent complex input‐output relationships.
• Further research into understanding the applicability of neural networks to determine snow properties is required to obtain results from large snow cover areas of the Himalayan region.

     

MWCNTs-ZrO2 as a reusable heterogeneous catalyst for the synthesis of N-heterocyclic scaffolds under green reaction medium

A simple, efficient, and facile heterogeneous multi-walled carbon nanotubes-zirconia nanocomposite (MWCNTs-ZrO₂) has been synthesized using natural feedstock coconut juice (água-de-coco do Ceará). The synthesized catalyst was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy analysis. The heterogeneous nanocomposite has been used for one-pot synthesis of various N-heterocyclic compounds like pyrazoles, 1,2-disubstituted benzimidazoles, 2-arylbenzazoles, and 2,3-dihydroquinazolin-4(1H)-ones under green reaction medium at room temperature. This novel method has several advantages, such as short reaction time, simple work-up, excellent yield, and green reaction conditions. The catalyst was recycled up to four times without significant loss in catalytic activity.     

Thermo and mechanoluminescence studies of BZT phosphor

Mechanoluminescence (ML) and thermoluminescence (TL) in barium zirconium titanate (BZT) is reported for the first time. The BZT powder sample, belonging to perovskite category is synthesized using solid state reaction technique. The sample is prepared at a temperature of 1200 °C. The obtained specimen is thoroughly characterized paying particular attention to their structure, composition, morphology and optical properties. The surface morphology and structural properties are analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD patterns confirm the formation of crystalline perovskite type cubic structure. Also, highly agglomerated, porous and regular shaped particles are seen by SEM. The optical properties of as prepared sample is presented and discussed in terms of ML and TL. The ML intensity is found to be maximum for the sample irradiated for 10 min. More than one maxima in TL glow curve reveals that the traps are distributed in separate groups at different depths and corresponding values are calculated using initial rise method.