Density and Diversity of Rotifers from Shore of a Flood Plain, Balloki Head Works Density & Diversity of Rotifers in Balloki Head Works

The present research work is an investigation of Rotifers from flood plains of Balloki Head Works using diversity indices. Objective: To study the density and diversity of rotifers of flood plain. Methods: collection of rotifers was done from the shore of flood plains from September to July. In total, 15 different species were identified. Rotifers were extracted from soil sample by a customized Baermann Funnel method. A moderate diversity of rotifers was explored by Shannon – Weaver. Simpson index of dominance supported this result. Analysis of variance (ANOVA) showed that there was no significant difference in population density of rotifers among months as the p-value was greater than 5% (α= 0.05). Population density of rotifers was negatively correlated with water temperature and pH whereas a positive correlation was observed with electrical conductivityResults: Overall a moderate diversity was observed. Rotifer density and distribution was under the influence of physico-chemical parameters.

Synthesis and Characterization of Biodegradable Amphiphilic Block Copolymer Containing Polycarbonates

Aliphatic polycarbonates are a newly emerging class of synthetic biodegradable polymers which are gaining attention due to their applications in biomedical fields including bond fixation, artificial skin, suture filaments, ligature clamps, devices for controlled drug release, bioresorbable prostheses, etc. Aliphatic polycarbonates possess several advantages compared to polyesters (other synthetic biodegradable polymers) that includes their resistance to acidic hydrolysis, thermal and hydrolytic stability, slow degradation rate and non-acidic degradation products. Most widely employed monomer for synthesis of aliphatic polycarbonate is trimethylene carbonate, a six membered cyclic carbonate, and its derivatives. Five-membered cyclic carbonates are not given much attention despite their huge potential as building blocks of biodegradable polymers. Polymerization of five-membered cyclic carbonates is associated with fractional decarboxylation during polymerization that leads to presence of ether linkages alongside targeted carbonate linkages. The demand of polycarbonates is significantly increasing due to their applications in various fields that inspired the improvement of synthesis methods. In this context, ethylene carbonate and propylene carbonate (five-membered cyclic carbonates) are polymerized in this study by ring-opening polymerization in the presence of sodium stannate trihydrate as a catalyst. Comprehensive microstructural analysis of the polymers was conducted by advanced one-dimensional (1H, 13C, DEPT-135o, & DEPT-90o) and two-dimensional nuclear magnetic resonance (NMR) techniques (COSY, TOCSY, HSQC & HMBC). The analysis revealed the co-existence of carbonate and ether units in polymer chain. Conversion and average ratio of carbonate to ether linkages of the polymer chains is quantified by 1H-NMR. Molar mass progression was evaluated by size exclusion chromatography. Selectivity of polymerization of both monomers with regard to polymerization speed, molar mass augmentation and relative ether to carbonate content as a function of polymerization conditions (such as temperature, monomer to initiator ratio, polymerization time and catalyst concentration) are evaluated. The polymers synthesized by ROP of ethylene carbonate and propylene carbonate are named as poly(ethylene ether-carbonate) and poly(propylene ether-carbonate), respectively. Furthermore, novel amphiphilic biodegradable di- and tri-block copolymers based on ethylene carbonate and propylene carbonate as hydrophobic segment while using methoxy poly(ethylene glycol)s and poly(ethylene glycol)s of varying molar masses as macro-initiator, were synthesized. Earlier elution of block copolymer from macro-initiator in size exclusion chromatography (SEC) indicated the successful synthesis of the block copolymers. Ratios of both types of blocks are varied systematically. Liquid chromatography at critical conditions for both hydrophilic and hydrophobic blocks are established to analyze the individual block length of non-critical blocks, and presence or absence of free critical blocks in the samples. Liquid chromatographic critical conditions of polymer synthesized by ROP of ethylene carbonate and propylene carbonate, poly (ethylene ether-carbonate) and poly(propylene ether-carbonate) respectively, were established for the first time. The established chromatographic critical points of PEG, PEEC and PPEC successfully tracked presence of homopolymers along with estimation of individual block lengths of the block copolymers. The synthesized biodegradable block copolymers can open new possibilities for modern drug delivery systems due to slow degradation rate and non-acid biodegradation products of polycarbonates.