RESUMEN
We demonstrate a refined way to extract the frequency noise (FN) spectrum of lasers by tailoring the delay in a conventional delayed self-heterodyne setup to sub-coherence lengths. The method achieves direct proportionality between electrical spectrum analyzer traces and the FN spectrum, which provide the intrinsic linewidth of the lasers. This proposed method is validated by comparing the FN spectrum with that obtained from a commercial frequency noise analyzer. The method provides a cost-effective alternative for FN measurements, which also requires minimal post-processing as compared to the state-of-the-art.
RESUMEN
There are several metal ions that are vital for the growth of the environmental field as well as for the biological field but only up to the maximum limit. If they are present in excess, it could be hazardous for the human health. With the growing technology, a series of various detection techniques are employed in order to recognize those metal ions, some of them include voltammetry, electrochemical methods, inductively couples, etc. However, these techniques are expensive, time consuming, requires large storage, advanced instrumentation, and a skilled person to operate. So, here comes the need of a sensor and it is defined as a miniature device which detects the substance of interest by giving response in the form of energy change. So, from past few decades, many sensors have been formulated for detecting metal ions with some basic characteristics like selectivity, specificity, sensitivity, high accuracy, lower detection limit, and response time. Detecting various metal ions by employing chemosensors involves different techniques such as fluorescence, phosphorescence, chemiluminescence, electrochemical, and colorimetry. The fluorescence technique has certain advantages over the other techniques. This review mainly focuses on the chemosensors that show a signal in the form of fluorescence to detect Al+3, Zn+2, Cu+2, and Fe+3 ions.
RESUMEN
Over the past few years, amino acids (AA) have emerged as promising biomaterials for the synthesis of functional polymers. Owing to the diversity of functional groups in amino acids, various polymerization methods may be used to make a wide range of well-defined functional amino-acid/peptide-based optically active polymers with varying polymer lengths, compositions, and designs. When incorporated with chirality and self-assembly, they offer a wide range of applications and are particularly appealing in the field of drug delivery, tissue engineering, and biosensing. There are several classes of these polymers that include polyamides (PA), polyesters (PE), poly(ester-amide)s (PEA)s, polyurethanes (PU)s, poly(depsipeptide)s (PDP)s, etc. They offer the ability to control functionality, conjugation, crosslinking, stimuli responsiveness, and tuneable mechanical/thermal properties. In this review, we present the recent advancements in the synthesis strategies for obtaining these amino acid-derived bio-macromolecules, their self-assembly properties, and the wealth of prevalent applications.
