Using line acceleration to measure false killer whale (Pseudorca crassidens) click and whistle source levels during pelagic longline depredation

False killer whales (Pseudorca crassidens) depredate pelagic longlines in offshore Hawaiian waters. On January 28, 2015 a depredation event was recorded 14m from an integrated GoPro camera, hydrophone, and accelerometer, revealing that false killer whales depredate bait and generate clicks and whistles under good visibility conditions. The act of plucking bait off a hook generated a distinctive 15 Hz line vibration. Two similar line vibrations detected at earlier times permitted the animal’s range and thus signal source levels to be estimated over a 25-min window. Peak power spectral density source levels for whistles (4–8 kHz) were estimated to be between 115 and 130 dB re 1 lPa2/Hz @ 1 m. Echolocation click source levels over 17–32 kHz bandwidth reached 205 dB re 1lPa @ 1 m pk-pk, or 190 dB re 1lPa @ 1 m (root-meansquare). Predicted detection ranges of the most intense whistles are 10 to 25 km at respective sea states of 4 and 1, with click detection ranges being 5 times smaller than whistles. These detection range analyses provide insight into how passive acoustic monitoring might be used to both quantify and avoid depredation encounters.The authors are indebted to Captain Jerry Ray and the rest of the F/V Katy Mary crew for permitting the camera gear to be deployed during their longline fishing trip. Robert Glatts designed the custom GoPro circuit board, and Will Cerf assisted with video footage analysis. This research was sponsored by Derek Orner under the Bycatch Reduction Engineering Program (BREP) at the National Oceanic and Atmospheric Administration (NOAA).Ye

Functional polymeric assembly materials via non-transition metal iodide catalyzed controlled radical polymerization

Chapter 1 introduces the advantages and disadvantages of the well-known living radical polymerization (LRP) systems. The advantages of reversible complexation mediated polymerization (RCMP) over other LRPs have been discussed. The self-assembly methods of block copolymers for generating self-assemblies and their influencing parameters have been discussed in brief. The motivations and aims for the works in this Thesis are discussed. In Chapter 2, Alkali metal iodides, NaI, KI, and CsI, and alkaline earth metal iodides, MgI2 and CaI2, were systematically studied as catalysts. Among the five catalysts, NaI exhibited a particularly high reactivity. NaI is also amenable to styrene, acrylonitrile, and functional methacrylates. In addition to homopolymers, NaI also afforded well-defined block copolymers, telechelic polymers, and a star polymer. The high monomer versatility and accessibility to a wide range of polymer architectural designs are desirable features of this polymerization system. In Chapter 3, NaI-catalyzed RCMP was combined with polymerization induced self-assembly (PISA) to generate self-assemblies. Poly(methacrylic acid) (PMAA) and poly(methyl methacrylate) (PMMA) were used as hydrophilic and hydrophobic segments, respectively, to generate self-assemblies. Micelles (nano-particles), worms (nano-cylinders), and vesicles (nano-capsules) were generated in ethanol at 5-9 wt% solid content. In Chapter 4, biocompatible polymer nano-capsules (or vesicles) were prepared using aqueous emulsion PISA (polymerization induced self-assembly) catalyzed by NaI. The hydrophilic and hydrophobic monomers used in this study were poly(ethylene glycol) methyl ether methacrylate (PEGMA) and methyl methacrylate (MMA), respectively. Spheres and vesicles were generated depending on the degrees of polymerization (DPs) of the hydrophilic and hydrophobic segments in the block copolymers. The nano-capsules (or vesicles) were successfully obtained with relatively high (8-9%) solid concentrations. The encapsulation property of the obtained vesicles was studied using a hydrophilic dye, i.e., Rhodamine-B. In a typical example loading capacity was 0.28% and the encapsulation efficiency 48%. In Chapter 5, we carried out RCMP of a macromonomer, i.e., poly(dimethylsiloxane) methacrylate (PDMSM), and prepared a bottlebrush polymer via a grafting-through approach. The obtained bottlebrush polymer (PPDMSM-I) was further used as a macroinitiator in the polymerization of a divinyl crosslinkable monomer, i.e., ethylene glycol dimethacrylate (EGDMA), yielding a bottlebrush particle. For comparison, we also synthesized particle whose shell consisted of a linear (non-bottlebrush) polymer, i.e., poly(methyl methacrylate) (PMMA). In tetrahydrofuran (THF), above a critical overlapping concentration (5 wt%) of the particle, the viscosity of the PMMA particle significantly increased because of the entanglement of the linear shell polymers, and the viscosity of the PPDMSM particle became much lower than that of the PMMA particle, demonstrating a better lubrication property of the bottlebrush particle. The observed lower viscosity of the PPDMSM particle is ascribed to the entropic repulsion of the sterically hindered bottlebrush polymer shell.Doctor of Philosoph

Processing and Characterization of In-Situ Generated Nanosilver and Er3+ Co-Doped Bromoborosilicate Glass Nanocomposites

In the present investigation, bromoborosilicate glass of composition 6Na(2)O-19K(2)O-10BaBr(2)- 2Al(2)O(3)-15B(2)O(3)-48SiO(2) (mole %) added with 0.2 wt% SnO, co-doped with 0.001 wt% Ag and 0.7 wt% Er2O3 in excess amount, was prepared by melt-quench technique. The metal-glass nanocomposites were derived involving a single-step in-situ thermochemical reduction of the precursor glass subjecting an isothermal heat-treatment protocol. The precursor glass and metal glass nanocomposites were characterized by dilatometer, differential scanning calorimeter, X-ray diffractometer, field emission scanning, electron microscope, transmission electron microscope, Fourier transform infrared spectrometer, UV-Vis-NIR spectrophotometer, fluorimeter etc. XRD spectra represent the amorphous nature of the samples and without having any sharp peaks of silver (Ag-0) and barium bromide (BaBr2). But the FESEM micrograph shows the presence of BaBr2 crystallites in clusters and the TEM micrograph shows the presence of Ag-0 nanoparticles of different shapes and sizes. The precursor glass sample shows sharp absorption peak at 378 nm and 521 nm due to the (4)G(11/2) and H-2(11/2) energy levels of Er3+ but glass nanocomposites exhibit another band at 410 nm due to the surface plasmon resonance of Ag-0 nanoparticles. They also show sharp emission peak at 1542 nm due to 4 vertical bar(15/2) -> (4)vertical bar(13/2) transition of Er3+ ions and prominent upconverted peaks at 630 nm (red, medium) and 645 nm (red, strong) due to F-4(9/2) -> (4)vertical bar(15/2) transition. The intensity of the absorption and upconverted peaks increases with the duration of heat treatment, having maximum intensity at 5 h and the intensity of the emission peak increases with heat treatment upto 1 h and then decreases for 5 h. Thus these metal-glass nanocomposites show enhanced photoluminescence upconversion and are promising material for different photonic applications

Networking of block copolymer nanoassemblies via digital light processing four-dimensional printing for programmable actuation

Controls over stimuli-responsive functional materials and programmable shape deformations are key features in the four-dimensional (4D) printing of soft actuators. Instead of using random copolymers, homopolymers, or natural polymers, this paper reports the first use of amphiphilic, photocurable, and pH-responsive block copolymer (BCP) nanoassemblies in digital light processing (DLP) 4D printing to fabricate smart and programmable soft actuators. Programmable actuation was studied via a bottom-up approach: (1) designed synthesis of pH-responsive BCPs, (2) nanoassembly structures of BCPs, and (3) networking of nanoassemblies via the photocuring process in DLP. As a proof-of-concept, bilayered grippers, ring-shaped actuators, and octopus-like actuators were programmed to produce a range of bending angles and actuation patterns. pH-responsive BCP nanoassemblies were also combined with commercially available three-dimensional printing liquid resin (PlasClear) to produce stimulus-responsive printing ink that was successfully used for 4D printing applications. Thus, smart and programmable materials were developed for 4D printing applications.National Research Foundation (NRF)Submitted/Accepted versionThis work was supported by National Research Foundation (NRF) Investigatorship in Singapore (NRF-NRFI05-2019-0001)

Synthesis of biologically decomposable terpolymer nanocapsules and higher-order nanoassemblies using RCMP-PISA

Terpolymers are used to generate bio-decomposable self-assemblies. PEG-PVL-PGMA terpolymers are synthesized via a combination of organocatalyzed living radical polymerization (RCMP) with polymerization-induced self-assembly (PISA), generating vesicle, multicompartment micelle (MCM), and core-compartmentalized worm (CCW), where PEG, PVL, and PGMA are poly(ethylene glycol) monomethyl ether, poly(δ-valerolactone), and poly(glycidyl methacrylate) and PGMA is grown during the PISA. MCM and CCW are uniquely obtainable using terpolymers. The PVL segment is biodegradable, and the obtained assemblies are bio-decomposable. Heavy metal-free and sulfur-free synthesis and bio-decomposability of the assemblies are attractive features.National Research Foundation (NRF)Accepted versionThis work was supported by the National Research Foundation (NRF) Investigatorship in Singapore (NRF-NRFI05-2019-0001)