Formation of Nanostructured Epoxy Networks Containing Polyhedral Oligomeric Silsesquioxane (POSS) and Silica Nanoparticles

This dissertation is focused on structure-property-processing relationship studies based on well-defined polyhedral oligomeric silsesquioxane (POSS) modified epoxy networks to present a comprehensive understanding of hybrid network behavior. In this research, a monoamine functional POSS molecule is incorporated into the epoxy monomer as pendant unit to mimic common epoxy structures and then crosslinked to form well-defined epoxy hybrid networks. The POSS cages behave as nanosized pendant unit in the epoxy matrices, while the mass fraction of POSS cages is varied and the effects on physical properties are examined with respect to changes in network architecture. A novel continuous reactor method is developed to synthesize POSS-DGEBA precursor with the aim of improving prereaction efficiency between aminopropyl isobutyl POSS and DGEBA. Studies suggest that by using a continuous reactor, full conversion of aminopropyl isobutyl POSS into the precursor was achieved in less than a minute, compared to several hours in a batch process. Fabricating transparent networks with large mass fractions of pendant POSS by the continuous reactor method demonstrates the concept of network modification by molecular level dispersion of pendant POSS. Physical and thermal properties of hybrid networks demonstrate structure property relationships with respect to POSS content, which appears to be true network behavior, given that a molecular level dispersion of pendant POSS in crosslinked epoxy networks has been achieved. Studies of nanostructured epoxy networks containing pendant POSS and non-functionalized silica nanoparticles (SNP) prepared using the continuous reactor method suggest that favorable interactions between pendant POSS and SNP surfaces enhance matrix nanoparticle interactions. Results suggest better dispersion of SNP and improved load bearing properties of these networks due to the favorable interaction between pendant POSS cage and SNP. This research reveals a unique strategy for molecular level dispersion of pendant POSS into epoxy networks with excellent control over nanostructure formation and properties, leading to increased strength through plasticization of glassy polymer networks

Structural insights into global mutations in the ligand-binding domain of VAR2CSA and its implications on placental malaria vaccine.

Abstract Placental malaria is a public health burden particularly in Africa as it causes severe symptoms and results in stillbirths or maternal deaths. Plasmodium falciparum protein VAR2CSA drives placental malaria (PM) in pregnant women by adhering to chondroitin sulfate A (CSA) on the placenta. VAR2CSA is a primary vaccine candidate for PM with two vaccines based on it already under clinical trials. The first cryo-EM three-dimensional structure of Pf CSA-VAR2CSA complex revealed crucial interacting residues considered to be highly conserved across P. falciparum strains. In the current study, we have conducted a global sequence analysis of 1,114 VAR2CSA field isolate sequences from more than nine countries across three continents revealing numerous mutations in CSA-binding residues. Further, structural mapping has revealed significant polymorphisms on the ligand binding surfaces. The variants from this limited set of 1,114 sequences highlight the concerns that are vital in current considerations for development of vaccines based on VAR2CSA for placental malaria

Character association studies in grape accessions selected from Leh district of Jammu and Kashmir

Characters association and path analysis was studied in fifty genotypically diverse grape (Vitis vinifera L.) accessions for 20 important quantitative characters. The genotypic and phenotypic association of yield was signifi-cantly positive with most of the studied characters except yield efficiency, berry weight and chemical characters. Yield was positively and significantly correlated (r) with bunch length (0.652), bunch breadth (0.584), bunch weight (0.946), number of bunches per vine (0.289), number of berries per bunch (0.672), berry length (0.337), berry breadth (0.363) and number of seeds per berry (0.612). Direct and positive effect was observed between yield and bunch and berry characters. Bunch breadth (1.538), number of bunches per vine (0.708), berry weight (1.112) ex-hibited a good amount of direct effect on yield and its correlation with yield was also positive. Hence it is clear from the present study that for selection of any accession in the crop due emphasis must be given on the yield and the associated characters which have direct and positive effect on the yield

Recent Advancements in Electrochemical Conversion of Carbon Dioxide

Electrochemical reduction of carbon dioxide into eco-friendly and clean products is a promising approach to eradicate pollution. Although carbon dioxide emission is inhibited by the advent of renewable sources of energy, it is present in the atmosphere and needs to be cleaned. The reduction of carbon dioxide from atmospheric gases can be accomplished by its adsorption and subsequent transportation to electrolytic chambers, where it is reduced to hydrocarbons, organic acids or carbonates. This review focuses on developing a three compartment electrochemical cell to reduce carbon dioxide used as a catholyte. Various factors affecting the electrochemical reduction of carbon dioxide and recent advancements in this field are deliberated

Waddling Gait: A complication of valproate therapy and a thought beyond vitamin D deficiency

Proximal muscle weakness is a common presentation in paediatric-orthopaedic clinics and is frequently paired with a vitamin D deficiency diagnosis. Recently, side effects of the extensive use of antiepileptic and antipsychotic drugs such as sodium valproate in childhood disorders are being documented. Sodium valproate causes a time-dependent, drug-induced proximal myopathy. We report a 13-year-old female patient who presented at the Orthopaedic Outpatient Department at Lady Hardinge Medical College, New Delhi, India, in 2019 with an abnormal gait. The patient was taking a combination therapy of sodium valproate, risperidone and trihexyphenidyl for absence seizures and a mood disorder. Following clinical investigations, the patient was diagnosed with proximal myopathy. As a result of elevated serum alkaline phosphatase and creatine kinase myocardial band levels, sodium valproate was replaced with ethosuximide and a carnitine supplementation was prescribed. The patient fully recovered and regained full mobility. Proximal myopathy had been incorrectly managed and assumed to be caused by a vitamin D deficiency.Keywords: Muscle Weakness; Carnitine; Myopathy; Valproic Acid; Vitamin D Deficiency; Gait; Case Report; India

Stability Analysis of Integrated Pest Management with Impulsive Biological Control

The aim of the present work is to study the dynamics of stage-structured pest control model including biological control, i.e. by releasing of natural enemies and infected pests periodically. It is assumed that only immature susceptible pests are attacked by natural enemies admitting Beddington DeAngelis functional response and mature susceptible pests are contacted by infected pests with bilinear incidence rate and become exposed. The sufficient condition for local stability of pest extinction periodic solution is derived by making use of Floquet’s theory and small amplitude perturbation technique. The global attractivity of pest extinction periodic solution is also established by applying comparison principle of impulsive differential equations

Pre-monsoon physico - chemical analysis of surface and ground water of Abhanpur block in district Raipur, (C.G.)

A segment of this investigation was carried out for pre-monsoon study of ground water as well as surface water physicochemical characteristics of Abhanpur block, district Raipur of Chhattisgarh. The geographical area at study is situated between 2103’N to 21035’4”N altitude and 81043’ E to 49.64’5” E longitude. The present work has been conducted by monitoring of ground and surface water i.e. well water and bore well water of 8 wards of Abhanpur Block as well as pond and tap water of the Abhanpur. Attempts were made to study and analyze the physico-chemical characteristics of water i.e. Temperature, pH, total dissolved solids, alkalinity, hardness and chloride

A rare case report of hysterotomy for retained placenta accreta in bicornuate uterus

Retained placenta is a common third stage complication. Placenta accreta is due to abnormal invasive placental implantation. Many cases of Post-partum haemorrhage (PPH) are caused by placenta accreta and may lead to peripartum hysterectomy. We here report a case of placenta accreta in a patient following two failed attempts of manual removal of retained placenta followed by conservative management with methotrexate in stable patient. Both attempts were unsuccessful and led to septicaemia, requiring delivery of placenta by hysterotomy