Sorption of Cadmium from Aqueous Solutions at Different Temperatures by Mexican HEU-type Zeolite Rich Tuff

Many factors may affect the heavy metals sorption on natural zeolites among them the temperature, for this reason in this paper the cadmium retention behavior on Mexican zeolitic rich tuff as a function of temperature is considered. The kinetic and the isotherms were determined at 303, 318, and 333 K, the remaining cadmium in the solution samples was analyzed by atomic absorption spectrometry. The pseudo-second order rate constant, k, as well as the apparent diffusion coefficients were calculated from the cadmium uptake by the zeolitic rock as a function of the contact time and temperature, the highest amounts were found for the experiments done at 333 K. The maximum cadmium adsorption capacity by the zeolitic material was 12.2 mg Cd²⁺/g at 318 K corresponding to 20% of the effective ion exchange capacity of the Chihuahua zeolitic rock. In order to explain the cadmium sorption behavior different kinetics and isotherm models were considered.     

Synthesis of novel spiro-[3H-indole-3,3′-[1,2,4]triazolidine]-2-ones via azomethine imines

Novel spiroindoles 5 are prepared easily via a one-pot, 1,3-dipolar cycloaddition reaction of azomethine imines with isatin imines under thermal conditions.     

Nontemplate Synthesis of Two Novel 23-Membered N3O4-Donor Macrocycles

Abstract

A novel 23-membered heptadentate N₃O₄ Schiff base ligand has been prepared by [1 + 1] cyclocondensation of 1,2-bis(2′-aminophenoxy)-4-t-butylbenzene with 2,6-bis(2-formylphenoxymethyl)pyridine by a nontemplate procedure. Treatment of L₁ with NaBH₄ in EtOH/CHCl₃ gave the di-amine macrocycle L_2.     

Effects of lipopolysaccharide-induced inflammation on expression of growth-associated genes by corticospinal neurons

Background  

Inflammation around cell bodies of primary sensory neurons and retinal ganglion cells enhances expression of neuronal growth-associated genes and stimulates axonal regeneration. We have asked if inflammation would have similar effects on corticospinal neurons, which normally show little response to spinal cord injury. Lipopolysaccharide (LPS) was applied onto the pial surface of the motor cortex of adult rats with or without concomitant injury of the corticospinal tract at C4. Inflammation around corticospinal tract cell bodies in the motor cortex was assessed by immunohistochemistry for OX42 (a microglia and macrophage marker). Expression of growth-associated genes c-jun, ATF3, SCG10 and GAP-43 was investigated by immunohistochemistry or in situ hybridisation.     

Microwave-Induced One - Pot Synthesis of some new Spiro [Indoline-3,2′-Thiazolidine]-2,4′(1H)-Diones and Bis [Spiro [Indoline -3,2′-Thiazolidine]-2,4′(1H)-Diones]

The title compounds have been obtained thermally and under microwave irradiation by condensation of isatin, aromatic amines and mercaptoacetic acid in good to excellent yields without isolating the imine intermediates.     

A pericyclic cascade to the stereocontrolled synthesis of 9-cis-retinoids

A domino reaction that is pericyclic in nature is thought to be triggered upon treatment of alkenynol 10 with arylsulfenyl chlorides. The process comprises an ordered sequence of sigmatropic rearrangements: a reversible [2,3]-allyl sulfenate to allyl sulfoxide shift, followed by a [2,3]-propargyl sulfenate to allenyl sulfoxide rearrangement, and last a stereodifferentiating [1,5]-sigmatropic hydrogen migration leading to polyene 13. The occurrence of the C7 to C11 hydrogen migration has been demonstrated by labeling experiments. The double diastereoselection of the [1,5]-sigmatropic hydrogen shift to afford a single isomer of the final polyene 13 is thought to arise from a combination of the electronic effect of the sulfoxide at one terminus, and the steric effect imparted by the bulky trimethylcyclohexenyl substituent at the other terminus. The overall process thus constitutes a stereoselective synthesis of an E,Z,Z-triene fragment from an alkenynol and, in particular, a retinoid with the 7E,9Z,11Z,13E configuration on the conjugated polyenic side chain. Application of this method to the synthesis of retinoids, including labeled analogues, is straightforward.