National Chemical Laboratory

About: National Chemical Laboratory is a facility organization based out in Pune, Maharashtra, India. It is known for research contribution in the topics: Catalysis & Nanoparticle. The organization has 8891 authors who have published 14837 publications receiving 387600 citations.

Unsaturated Polyesters from PET Waste: Kinetics of Polycondensation

Abstract: PET waste was glycolyzed by propylene glycol at different weight ratios. The glycolyzed products were analyzed for hydroxyl value, number average molecular weight, and the amount of free glycol. The glycolyzed products were reacted with maleic anhydride at a hydroxyl to carboxyl ratio of 1.1. The control resin was a general purpose unsaturated polyester prepared by reacting phthalic anhydride, maleic anhydride, and propylene glycol. The heating schedule of the polyesterification was comparable to that normally employed in the industrial process, with two isothermal plateau of 3–4 h at 180 and 200°C. The rate of reactions and rate constants were determined separately at 180 and 200°C. The kinetics of the PET-based unsaturated polyesters was compared with that of the general purpose resin. It was found that the PET waste could be depolymerized by propylene glycol to a molecular weight range of 276–480. The polyesterification reactions followed a third-order kinetics. The rates of polyesterification of PET based systems were higher than that of the general purpose resin. PET-based systems were higher than that of the general purpose resin. PET-based systems took about 10 h to reach an acid value of 32 mg KOH/g whereas the general purpose resin took about 25 h to reach the same acid value.

Syntheses, Crystal Structures, and Magnetic Properties of Metal–Organic Hybrid Materials of Co(II) Using Flexible and Rigid Nitrogen-Based Ditopic Ligands as Spacers

Abstract: A carboxylate-based flexible ligand, 5-(4-carboxybenzyloxy)isophthalic acid (p-cbiaH3), readily reacts with Co(II) salts in the presence of different pyridine-based coligands such as 4-bis(4-pyridinylmethyl)piperazine (bpmp) or 1,2-di(4-pyridyl)ethylene (dpe) under hydrothermal conditions to afford two different three-dimensional (3D) coordination polymers, {[Co4(OH)2(p-cbia)2(bpmp)-(H2O)3]·2H2O}n (1) and {[Co4(OH)2(p-cbia)2(dpe)(H2O)4]·2H2O}n (2). Both compounds have been characterized by X-ray crystallography, IR spectroscopy, thermogravimetry, and elemental analysis. Single-crystal X-ray diffraction studies reveal that both compounds consist of a tetranuclear core [Co4(μ3-OH)2]6+. Compound 1 is a unprecedented 3D non-interpenetrated (3,4,9)-connected pkb3 net. On the other hand, compound 2 is a 2-fold interpenetrated (3,8)-connected tfz-d net. Variable temperature static and dynamic magnetic measurements show that both compounds exhibit ferromagnetic behavior associated with mixed hydroxyl/carboxylate-...

Dementia with Lewy bodies and Parkinson's disease with dementia: where two worlds collide.

Abstract: Parkinson's disease and dementia with Lewy bodies are two common presentations of a single, underlying disease process (Lewy body disease) which is thought to be related to dysregulation of the synaptic protein, alpha-synuclein. This article discusses the nature of the relations between Parkinson's disease and dementia with Lewy bodies, and what can be learned from them about the causes of dementia in patients with established Parkinson's disease. This is an area of clinical practice which is of increasing importance as greater numbers of ageing patients survive longer with good treatment of their motor symptoms. Precise use of terminology and a clear understanding of the biological substrates underlying symptom formation are particularly helpful to both clinicians and patients.