Long-range entanglement in quantum spin liquids (QSLs) leads to novel low-energy excitations with fractionalized quantum numbers and (in two dimensions) statistics. Experimental detection and manipulation of these excitations present a challenge particularly in view of diverse candidate magnets. A promising probe of fractionalization is their coupling to phonons. Here, we present Raman scattering results for the S = 1/2 honeycomb iridate Cu 2 IrO 3 , a candidate Kitaev QSL with fractionalized Majorana fermions and Ising flux excitations. We observe anomalous low-temperature frequency shift and linewidth broadening of the Raman intensities in addition to a broad magnetic continuum, both of which, as we derive, are naturally attributed to the phonon decaying into itinerant Majoranas. The dynamic Raman susceptibility marks a crossover from the QSL to a thermal paramagnet at ∼120 K. The phonon anomalies below this temperature demonstrate a strong phonon-Majorana coupling. These results provide evidence of spin fractionalization in Cu 2 IrO 3 .
Over the past few decades, chitosan (CS) has gained the attention of researchers investigating newer biomaterial-based carriers for drugs in pharmaceutical and biomedical research. Combined with its nontoxic behavior, biodegradability, and biocompatibility, chitosan has found widespread applications in the fields of drug delivery, tissue engineering, and cosmetics. As a novel drug carrier, chitosan is regarded as one of the promising biomaterials in the pharmaceutical industry. The extensive use of this cationic biopolysaccharide in the delivery of therapeutic agents has brought a few limitations of chitosan into the limelight. Various chemical modifications of chitosan can minimize these limitations and improve the efficacy of chitosan as a drug carrier. The effectiveness of several chemically modified chitosan derivatives, including trimethyl chitosan, thiolated chitosan, PEGylated chitosan, and other chitosan derivatives, has been investigated by many researchers for the controlled and target specific delivery of therapeutics. The chemically modified chitosan derivatives exhibited greater importance in the current scenario on drug delivery due to their solubility in wide range of media along with their interaction with pharmaceutically active ingredients. Chitosan derivatives have also attracted attention in several biomedical fields, including wound healing, hyperthermia therapy, tissue engineering, and bioadhesives. The present review narrates the sources and common physicochemical properties of chitosan, including several important synthetic modifications to obtain chemically modified chitosans and their applications in targetspecific drug delivery, along with several biomedical applications.
In formulations or medicinal preparation the Active Pharmaceutical Ingredient are the substances, which are responsible for therapeutic activity. The quality of a medicinal preparation is related to all the factors, which contribute directly or indirectly to the safety, stability effectiveness & acceptability of the products. These molecules are obtained from various sources like naturally occurring substances, semi synthetic and synthetic routes. Therefore the quality must be built in the products during the research and development stage of the product itself. A large number of appropriate reagents solvents and synthetic routes are used to bring about the reaction of a pharmaceutically active molecule. As a result during the preparation of the molecule many unwanted but related compounds and byproducts may form along with the required molecule. Appropriate methods are developed to purify the reaction product to obtain the Active Pharmaceutical Ingredient to maximum purity. These impurities are also termed as related substance in the Pharmacopoeia or official texts. These impurities when they are present within the limits prescribed in the pharmacopoeia are harmless. Thus it is necessary to have these impurities in a pure form, so that we can compare the purity of the drug. In the present study related substance of cephalexin an antibiotic drug were synthesized, and the impurities are then compared identified and quantified using analytical methods such as HPLC.
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