A Prompt Study on Recent Advances in the Development Of Colorimetric and Fluorescent Chemosensors for "Nanomolar Detection" of Biologically Important Analytes

Fluorescent and colorimetric chemosensors for selective detection of various biologically important analytes have been widely applied in different areas such as biology, physiology, pharmacology, and environmental sciences. The research area based on fluorescent chemosensors has been in existence for about 150 years with the development of large number of fluorescent chemosensors for selective detection of cations as metal ions, anions, reactive species, neutral molecules and different gases etc. Despite the progress made in this field, several problems and challenges still exist. The most important part of sensing is limit of detection (LOD) which is the lowest concentration that can be measured (detected) with statistical significance by means of a given analytical procedure. Although there are so many reports available for detection of millimolar to micromolar range but the development of chemosensors for the detection of analytes in nanomolar range is still a challenging task. Therefore, in our current review we have focused the history and a general overview of the development in the research of fluorescent sensors for selective detection of various analytes at nanomolar level only. The basic principles involved in the design of chemosensors for specific analytes, binding mode, photophysical properties and various directions are also covered here. Summary of physiochemical properties, mechanistic view and type of different chemosensors has been demonstrated concisely in the tabular forms.

Synergistic Dual-Atom Molecular Catalyst Derived from Low-Temperature Pyrolyzed Heterobimetallic Macrocycle-N4 Corrole Complex for Oxygen Reduction

A heterobimetallic corrole complex, comprising oxygen reduction reaction (ORR) active non-precious metals Co and Fe with a corrole-N4 center (PhFCC), is successfully synthesized and used to prepare a dual-atom molecular catalyst (DAMC) through subsequent low-temperature pyrolysis. This low-temperature pyrolyzed electrocatalyst exhibited impressive ORR performance, with onset potentials of 0.86 and 0.94 V, and half-wave potentials of 0.75 and 0.85 V, under acidic and basic conditions, respectively. During potential cycling, this DAMC displayed half-wave potential losses of only 25 and 5 mV under acidic and alkaline conditions after 3000 cycles, respectively, demonstrating its excellent stability. Single-cell Nafion-based proton exchange membrane fuel cell performance using this DAMC as the cathode catalyst showed a maximum power density of 225 mW cm^-2 , almost close to that of most metal-N4 macrocycle-based catalysts. The present study showed that preservation of the defined CoN4 structure along with the cocatalytic Fe-Cx site synergistically acted as a dual ORR active center to boost overall ORR performance. The development of DAMC from a heterobimetallic CoN4-macrocyclic system using low-temperature pyrolysis is also advantageous for practical applications.

Assessing the Attitude of Parents Towards Various Behaviour Management Techniques Used during Paediatric Dental Treatment: A Cross-sectional Study

Introduction: Every child who enters the dental clinic is different. Some of them are anxious, some are scared, some are angry, and some are confused. Rarely, children exhibit a positive behaviour, most of them being uncooperative. The child’s behaviour in turn influences the efficiency and outcome of the dental treatment. Aim: To assess parents or caregivers’ acceptance of various Behaviour Management Techniques (BMT) through direct observation and feedback received. materials and methods: A cross-sectional study was planned to assess the most preferred BMT. The study was conducted from November 1st, 2018 to October 31st, 2019 for a period of one year. Parents of children between the ages of four to nine years were included in the study using non random convenience sampling with 675 participants. Every parent was given an explanation about the study and briefed about nine major BMTs in regional language. Audiovisual aid for each technique in their own mother tongue was displayed via a projector and sound systems and parents were asked to watch it. Later they were given a Visual Analog Scale (VAS) of 10 mm length with markings, printed on a sheet of paper to assess the preference for each technique. Collected data was entered in an excel sheet and analysis was done using median test. Results: The results showed that 32.4% i.e., the highest percentage of people opted for Tell Show Do (TSD), indicating that TSD is the best BMT. Professional status of parent showed a significant impact on BMT selection. Conclusion: This study reveals that amongst all the behaviour management methods, ‘Tell-Show-Do’ was the most accepted BMT by the parents and the professional background of the parent has a statistically significant role in the selection of BMT.