Toughening of isothermally polymerized cyclic butylene terephthalate for use in composites

Interest in thermoplastic composites is growing because of their advantages over thermosets in recyclability and in toughness. The melt viscosity of thermoplastic polymers is very high, which makes fibre impregnation difficult. This can be solved by using in-situ polymerization with cyclic butylene terephthalate (CBT). However this leads to a brittle PBT. To solve this problem physical and chemical modification of the polymerized CBT (pCBT) was performed, to disturb the crystallization. Chemical modification with PC and with PTHF has an embrittling effect because of a bad chemical interaction. When polycaprolactone is added to the CBT a copolymer is formed which leads to a lower crystallinity, resulting in a higher toughness of the pCBT. This tougher matrix material was used in composites and a two times tougher composite is produced when only 7 wt% PCL is added to the CBT. The physical modification evaluated was the addition of carbon nanotubes (CNT). Although an increase in stiffness and strength of the pCBT is seen when CNTs are added up to 0.1 wt%, the failure strain decreases.     

A new and sensitive method for the spectrophotometric determination of ethion in environmental and biological samples

A new and sensitive spectrophotometric method is described for the determination of sub ppm levels of the organophosphorus pesticide ethion based on the oxidation of ethion by potassium permanganate in phosphoric acid to sulphones and its hydrolysis under acidic condition at 100°C to release formaldehyde, which is then determined by a reaction with 1,3,5-trihydroxybenzene (phloroglucinol) in alkaline medium. Beer's law is obeyed in the range of 0.1–0.8 ppm of ethion at 460 nm. The analytical parameters have been optimized.     

Spectrophotometric determination of baygon and carbaryl in air

A spectrophotometric method for the determination of baygon and carbaryl in air is based on the coupling of their hydrolysation products with diazotised p-amino-acetophenone. The dyes formed are measured at 580 nm and 555 nm, respectively. Beer's law is obeyed in the range of 0.9–5.6 mg/m³ and 0.4–3.6 mg/m³.     

Physicochemical Studies on Cesium Soaps. I. Thermogravimetry and Infrared Absorption Spectra

The infrared absorption spectra of cesium stearate was compared with that of stearic acid, sodium stearate, and rubidium stearate. It is concluded that the fatty acids in the solid state exist with a dimeric structure through hydrogen bonding whereas the alkali metal soaps are ionic in nature. Thermogravimetric analysis shows that the decomposition reaction of the alkali metal soaps is kinetically of zero order and the activation energy for the process lies in the range of 2 to 6 kcal/mol.     

Synthetization and Functionalization of Natural,Polymer, and Quantum-Based Carbon Nanodots and Their Application in Biomedicine

Carbon nanodots (CNDs) are a developing branch of nanomaterials and nanoscience. This has generated much more interest in the field and class of biomedicine science by way of unique particular properties, such as high stability, great photoluminescence, easy green synthesis, and simple surface modification. Numerous applications, such as bioimaging, biosensing, and treatment, have made use of CNDs. This review describes the most recent developments in CND research and talks about major changes in the understanding of CNDs and their prospects as biomedical tools. The importance of this work lies in the ability of CNDs to overcome many of the limitations associated with traditional materials used in biomedicine, such as toxicity, poor biocompatibility, and limited functionality. Furthermore, the use of CNDs as drug carriers, imaging agents, and sensors has shown great potential in improving the diagnosis and treatment of various diseases. The novelty of this work lies in the diversity of approaches used in the synthesis and functionalization of CNDs, and the unique properties of CNDs that make them versatile tools for biomedicine. In particular, the ability to tune the size, shape, and surface chemistry of CNDs allows for the creation of tailored materials with specific biomedical applications. The review also discusses the challenges and future prospects of CNDs in biomedicine, including the need for standardization and optimization of CND synthesis, functionalization, and characterization protocols.