Shrinking boreal lakes as agents of change: untangling structure and function in hydrologically-coupled lakes and wetlands

Thesis (Ph.D.) University of Alaska Fairbanks, 2018Widespread lake shrinkage has occurred over the last 30 years throughout interior Alaska and other boreal regions. This trend has been broadly linked to climate change, via multiple proximate drivers including permafrost thaw, shifting water balance, and terrestrialization caused by peat growth. The ecological effects of shrinking boreal lakes are still poorly understood. I used space-for-time substitution based on field surveys from a spatially balanced random sample of lakes (n=130) to examine the implications of shrinking lakes in the lowland floodplain of the Yukon River within the Yukon Flats National Wildlife Refuge in northern Alaska. Historical lake shrinkage over the last 30 years increased plant functional diversity, woodiness and aboveground biomass in lake-margin wetlands, despite a significant loss of wetland and lake area. Shrinking lakes appeared to have decreased hydrological connectivity with surrounding wetlands, and reduced organic carbon and nitrogen inputs from the surrounding landscape. However, land cover and bathymetry were better predictors of water chemistry than lake shrinkage. Continued reductions in lake surface area, combined with terrestrial succession, may reduce wetland area and increase the relative abundance of woody wetland vegetation compared to herbaceous plants. Lake shrinkage could also reduce below-ground C stocks, because lake sediments contain more organic C per m² than terrestrial soils, and lake sediment C appears vulnerable to aerobic decomposition. Overall, lake shrinkage will most likely affect plant and animal biodiversity, waterfowl and wildlife habitat quality, and C storage in contrasting ways, and management of drying landscapes may require difficult tradeoffs to be made as a result. These decisions would be aided by process-based modeling that accounts for the role of plant functional traits and explicitly represents hydrological interaction between terrestrial and freshwater ecosystems

Novel Ophthalmic Formulations For Improved Natamycin Delivery In Fungal Infections Of The Eye.

Natamycin (NT) is a front-line drug in the management of ocular fungal infections (OFI). An ophthalmic marketed NT suspension (Natacyn®) is currently the only FDA approved medication prescribed in the pharmacotherapy of OFI. Current NT pharmacotherapy requires frequent topical administration (every hour or 2-hours over 6-8 times in a day) due to it being instilled as eye-drops. This leads to higher precorneal losses and subsequent poor permeation and bioavailability. Therefore, in this research study, alternative ocular formulations of NT were investigated with an intent to improve precorneal retention and corneal permeation in comparison to Natacyn®. Chapter 1 discusses various aspects of NT such as its chemistry and pharmacology, antifungal spectrum and potential for development of resistance, ocular clinical evaluations, and specifics on Natacyn® to obtain a perspective of NT use in OFI. Chapter 2 reports the preparation and optimization of NT loaded surface coated PEGylated NLC (NT-PEG-NLC) using Box-Behnken Design. The optimized NT-PEG-NLC were found to have desirable physicochemical characteristics and exhibited significantly higher transcorneal permeation than Natacyn®, in vitro. In vivo ocular biodistribution of NT-PEG-NLC indicated that, despite NT load in NT-PEG-NLC (0.3%) being 1/16th of Natacyn® (5%), NT-PEG-NLC permeated the intact cornea to reach the inner tissues. To further improve ocular delivery of NT, chapter 3 reports on the development of a gelling system using a full factorial design in which the optimized NT-PEG-NLCs were loaded. This gelling system at a lower NT concentration (0.3%) compared to Natacyn® (5%), displayed superior pharmacokinetic parameters in the tear film and comparable NT concentrations in the inner ocular tissues (in vivo) at a 16-fold lower dose; indicating its potential ocular applications. Chapter 4 reports on the design of Eudragit™ RLPO based ocular films for ocular delivery of NT using central composite design. An optimized film formulation was selected on the bases of the interaction plots between the independent factors and dependent variables; and, it exhibited significantly higher transcorneal permeation (ex vivo) and superior pharmacokinetic parameters (in vivo) compared to Natacyn®. These observations imply that, NT-loaded films could also be explored as alternative dosage forms in the management of OFI

Report of Platythomisus octomaculatus (C. L. Koch, 1845) and Platythomisus sudeepi Biswas, 1977 from India (Araneae, Thomisidae)

The genus Platythomisus Doleschall, 1859 presently comprises 13 valid species, nine known from Africa and four from Asia. All Platythomisus species are known from females only, except P. jucundus Thorell, 1894 and P. sudeepi Biswas, 1977 from both sexes and P. quadrimaculatus from juvenile. Only, P. sudeepi was reported from India. Platythomisus octomaculatus (C. L. Koch, 1845) is recorded after 120 years of its last report; newly recorded from Assam, India which extends its distribution from the previously known localities, Java and Sumatra. Platythomisus sudeepi is newly recorded from the Maharashtra State. The variation in the number of abdominal spots on juvenile, sub-adult and adult of P. octomaculatus observed during rearing is reported. Although, the species name 'octomaculatus' suggests eight spots, we observed that the anterior pair of abdominal spots is fused in adults

A novel fluorescent "turn-on" chemosensor for nanomolar detection of Fe(III) from aqueous solution and its application in living cells imaging

An electronically active and spectral sensitive fluorescent “turn-on” chemosensor (BTP-1) based on the benzo-thiazolo-pyrimidine unit was designed and synthesized for the highly selective and sensitive detection of Fe³⁺ from aqueous medium. With Fe³⁺, the sensor BTP-1 showed a remarkable fluorescence enhancement at 554 nm (λex=314 nm) due to the inhibition of photo-induced electron transfer. The sensor formed a host-guest complex in 1:1 stoichiometry with the detection limit down to 0.74 nM. Further, the sensor was successfully utilized for the qualitative and quantitative intracellular detection of Fe³⁺ in two liver cell lines i.e., HepG2 cells (human hepatocellular liver carcinoma cell line) and HL-7701 cells (human normal liver cell line) by a confocal imaging technique

Performance Comparison of Twisted Tape and Screw Tape Inserts in Square Duct

Effects of insertion of a full length twisted tape and full length screw tape insert in a concentric double pipe heat exchanger ,square duct inner, and circular annulus on heat transfer and pressure drop characteristics were experimentally studied. Experiments were carried out under constant wall temperature using water as working fluid. Stainless steel twisted tape and screw tape inserts have equal twist ratio(y=4.0).Cold water flows through inner square duct, and hot water flows through circular annulus, in counter current fashion. Screw tape inserts found better over twisted tape from thermal performance point of view. Results of the Isothermal friction factor for the present twisted tape and helical screw-tape are higher than those for the plain duct around 7.7 times and 14 times respectively. Experiments were conducted well within laminar region. Over entire investigated laminar range, mean Nusselt number for the present twisted tape and helical screw tape are higher than those for the plain duct around 2.85 times and 5.3 times respectively. Further, Thermal performance ratio of twisted tape and screw tape inserts were found 2.81 and 3.52 times the plain square duct on constant pumping power respectively

Neuro-Fuzzy System based Handwritten Marathi Numerals Recognition System

Character Recognition is one of the important tasks in Pattern Recognition. The complexity of the character recognition problem depends on the character set to be recognized. In this paper it is developed 0ff-line strategies for the isolated handwritten Marathi numerical (0 to ९) with Neuro fuzzy logic has been provided. The neural fuzzy system is considered for soft computing.  This method improves the character recognition method. Neuro Fuzzy System is integration of Neural Network and Fuzzy logic. In that we are using neural fuzzy system for classification

Experimental & Finite element Analysis of Composite Mono Leaf Spring

In order to economize energy and conserve natural resources, weight reduction has been the main focus of automobile manufacturers in the present scenario. The increasing competition and innovations in automobile sector tends to modify the existing products or replacing old products by new and advanced materials. More efforts have taken in order to increase the comfort of user. The aim of this paper is to present a low cost fabrication of complete mono composite leaf spring. Single leaf, variable thickness, variable width spring of glass fiber reinforced plastic (GFRP) with similar mechanical and geometrical properties to the multi leaf steel spring, was designed, fabricated and tested. The finite element analysis of composite spring carried using ANSYS software. The experimental test is carried to verify the FEA result. Comparison between the performance of the GFRP and the multi leaf steel springs is presented