Coconut husk-lignin derived carbon dots incorporated carrageenan based functional film for intelligent food packaging.

Carbon dots (CDs) derived from sustainable natural feed-stocks like lignin have gained wide acceptance by virtue of their renewability and promising potential in intelligent sensing applications. The precursor lignin is isolated from agro-biomass waste, coconut husk through sodium hydroxide based extraction process. CDs are synthesised from amine functionalized lignin through solvothermal process and integrated into carrageenan biopolymer matrix (1, 2 and 3 wt%). The composite film with 2 wt% CDs (CARR2CD) showed optimum fluorescent emission intensity, excellent pH dependent fluorescent color change in the food pH range, reasonable tensile strength (46.50 ± 1.32 MPa) and 27 % increase in elongation at break. CDs imparted UV-light blocking properties (70 % UV-light) and enhanced hydrophobicity of the carrageenan matrix. CARR2CD film showed 84 % visible light transparency, 79 % reduction in oxygen transmittance rate (OTR), 81 % reduction in CO2 gas permeability and excellent antioxidant and antibacterial properties (against E. coli and S. aureus). As a practical application, the developed responsive packaging material is used to track pH change associated with milk spoilage via noticeable color change in fluorescent emission of the composite film. Thus, the developed responsive composite film paves a way for use as green and sustainable transparent intelligent food packaging material.

Methacrylated alkali lignin grafted P(Nipam-Co-AAc) copolymeric hydrogels: Tuning the mechanical and stimuli-responsive properties.

The current study reports the preparation of lignin grafted temperature and pH responsive hydrogels through copolymerization of N-isopropylacrylamide, acrylic acid and varying amount of lignin methacrylate (LMA = 50, 100, 150 and 200 mg) as crosslinker adopting radical polymerization technique. Functional group and structural characterizations were carried out to confirm hydrogels synthesis and their network structure. The variation in pore size on addition of lignin revealed the tuning of pores as well as swelling capacity of the hydrogels by suitable amount of LMA. All LMA grafted hydrogels showed temperature responsive behavior and pH dependent sensitivity in swelling, with reduced equilibrium swelling capacity values compared to sample without lignin. In alkali medium at room temperature, the maximum swelling capacity with 48% higher retention was noticed, while a significant reduction in swelling was observed at 40 °C in all media. The addition of lignin still preserved the tensile strength up to 100 kPa and compressive load bearing ability up to 30 kPa in freeze dried state with adequate interfacial stress transfer. An increase in lignin concentration showed enhanced storage modulus (~two-fold increase), adequate loss modulus values and improved cell viability, which paves the way for possible biomedical applications.

Fluorescence quenching based detection of nitroaromatics using luminescent triphenylamine carboxylic acids.

Detection of nitroaromatics employing greener techniques has been one of the most active research fields in chemistry. A series of triphenylamine (TPA) functionalized carboxylic acids were synthesized and characterized using various spectroscopic techniques including single-crystal X-ray diffraction analysis. The interaction of carboxylic acid-decorated TPAs with nitroaromatic compounds was photophysically explored using absorption and emission spectroscopy. Stern-Volmer plot accounts for the appreciable quenching constant of the TPA-acids. Density functional theory calculations were carried out to study the new compounds' frontier molecular orbital energy levels and the possible interactions with picrate anion and revealed an unusual charge transfer interaction between acids and picrate anion. The contact mode detection shows the TPA-acids can be used as dip-strip sensors for picric acid detection.

Strategies for COVID-19 control among migrant labourers in a developing country setting: Pathanamthitta model from Kerala.

BACKGROUND: The ongoing pandemic of Covid-19 is a public health emergency with serious implications world-wide including India. Vulnerable population like migrants are often left out of epidemic preparedness planning and reaching out these marginalized population is a challenge. OBJECTIVE: To describe different strategies implemented for control and prevention of Covid-19 among migrants in Pathanamthitta. RESULTS: Strategies for Covid-19 control among migrant labourers were planned and implemented with intersectoral coordination and community participation. Line listing and risk stratification, mobilisation of community volunteers, contactless active symptomatic surveillance using technology, IEC activities for awareness generation in multiple languages, sample collection, testing and distribution of personal protective equipment's were initially implemented. Setting up of a call centre facility assisted with M health technology exclusively for addressing concerns of migrants was first and one of its kind in the country. In addition to that special measures were taken to improve adherence and wellbeing of migrants which included addressing medical needs of migrants including psychological needs, ensuring food security, migrant hostels for the providing shelter, basic health care, isolation facilities and arranging transportation facilities for more than 10,000 stranded migrants. The success of these strategies was evident from the fact that not even a single migrant labourer was tested positive in the district during this period. CONCLUSION: Pathanamthitta district being in a resource constraint setting showed a very effective model by implementing technology assisted strategies tailored to the needs of population.The success of these highly effective and replicable strategy underlines the need to incorporate principles of primary health care in crisis management.