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The purpose of the present study was the development of an accurate method to determine the degree of substitution (DS) of modified hyaluronic acid (HA) by proton nuclear magnetic resonance (H NMR) spectroscopy. The influence of the effect of ionic strength and pH on H NMR spectra of HA was studied. The results showed a correlation between the conformation of HA in solution and the quality of the H NMR spectra. The best spectra with full proton mobility are obtained when HA is dissolved in DO with 2 M NaCl or DO with 0.1 M NaOD with a maximum concentration of 5 mg/ml. Under those conditions the size of the polymer coils is reduced below the concentration of chain overlap point, all the protons show the same response and a correct degree of substitution can be determined.
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http://dx.doi.org/10.1016/j.carbpol.2018.10.003 | DOI Listing |
Chem Biodivers
September 2025
Department of Chemistry, Govt. Raza P.G. College, Rampur, India.
Parasitic diseases continue to be a major public health burden, particularly in low- and middle-income countries. With the emergence of drug-resistant strains and limitations of current therapies, there is a growing interest in natural products as alternative treatment options. Coumarins, a diverse class of plant-derived secondary metabolites, have shown significant potential as antiparasitic agents.
View Article and Find Full Text PDFOrg Lett
September 2025
Department of Chemistry, University of Calcutta, 92 A. P. C. Road, Kolkata-700009, India.
This study introduces microwave-assisted, Fe(III)-catalyzed ring-opening annulations of isoxazoles, enabling the rapid and selective synthesis of 1,4-diacyl pyrroles and substituted pyridines. By leveraging microwave irradiation and transition metal catalysis, this approach enhances the reaction efficiency, reduces reaction times, and promotes high regioselectivity under mild conditions. Under thermal conditions, the Ru(II) catalyst led to the synthesis of nicotinamide derivatives.
View Article and Find Full Text PDFFront Vet Sci
August 2025
Immunology Unit, Department of Physiology, Faculty of Veterinary, Universidad de Extremadura, Cáceres, Spain.
Virtual laboratories provide a risk-free environment for students to conduct experiments, particularly those involving hazardous materials or complex procedures. Previous studies have shown that gamified elements and interactive tools enhance the interest of students and promote active participation. In the case of Immunology in the veterinary degree, our prior observations indicate that veterinary students experience learning difficulties with topics related to molecules and effector functions of the immune system.
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September 2025
Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana 47907, United States.
Alzheimer's disease (AD) and Parkinson's disease (PD) are the most prevalent neurodegenerative disorders characterized by continuous loss of functional neurons. The numbers of AD and PD patients will likely double by 2060 and 2040, reaching 13.9 and 1.
View Article and Find Full Text PDFCarbohydr Polym
November 2025
Department of Food Science and Engineering, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China. Electronic address: