Optimization and characterization of silver nanoparticle synthesis from the microalgae, Isochrysis galbana

The present study was aimed to carry out a green synthesis of Silver Nano Particless by using marine micro algae and its characterization by SEM, EDAX, Particle analyzer and Zeta potential. Microalgae samples (Isochrysis galbana and Nannochloropsis sp.) were collected from phytoplankton laboratory, Tuticorin Research Centre of ICAR-Central Marine Fisheries Research Institute. The culture media of I. galbana and Nannochloropsis sp. were taken for the preliminary synthesis of SNPs. Hence, Nannochloropsis sp. was not synthesized for its SNPs, I. galbana was selected for further study. Culture media, cell filtrate and supernatant of I. galbana were subjected to the SNPs synthesis in order to find out the maximum yield of silver with low chloride content. Among these, the supernatant of I. galbana showed maximum yield with low chloride content. It was confirmed by colorimetric reading at 450 nm. Synthesized SNPs from I. galbana contained 80.68% of silver and 15.25% of chloride as detected by EDAX analysis. Size of the SNPs was analyzed by particle analyzer and ranged from 16.6 to 205.3 nm and average size was 40.6 nm. Zeta potential of SNPs from I. galbana was -44.0 mV, which reveals the high stability of SNPs. This is the first authenticated work of I. galbana with respect to complete characterization of its SNPs

The Next Generation: Creating New Peace Processes in the Middle East

This essay describes how Israeli students in a course on mediation and consensus building taught in an Israeli university law department by and American law professor and an Israeli instructor analyzed and studied the conflict in the Middle East. It describes the suggestions they made for process design for the next stages of whatever peace process might emerge for the region. In light of the students\u27 suggestions, the authors present some ideas as to how different approaches to reconciliation and peace might be used, managed, and coordinated

Laminar heat transfer for small Prandtl number fluids including step change in wall temperature

The object of this investigation is to provide a simple means of determining the heat transfer from a flat plate which has an unheated leading length x₀. The case of steady, two-dimensional, laminar flow of an incompressible fluid with a Prandtl number of less than one is considered. Since there exists an unheated length and the Prandtl number of the fluid is less than one, the thermal boundary layer intersects the flow boundary layer. Thus, the solution of the problem divides into two regions. In this study, the problem is solved analytically by employing the energy integral equation. The temperature profile and velocity profile of the fluid are expressed using both linear and cubic polynomials. When the thermal boundary layer is outside the hydrodynamic boundary layer, the integration is performed in two operations. The result obtained from the energy integral equation by substituting both the temperature and velocity profiles is a first order, non-linear differential equation. The solution of this differential equation for the cubic profile case is rather complicated and tedious. However, curves are provided which give the appropriate parameters of the final results. The local and average convective coefficients can then be deduced based on the solution of this differential equation. The results from this investigation are compared with those of other investigators for several special cases. An excellent agreement is obtained between the two sets of results. It is found that significant errors may occur if previous solutions for special cases are employed for the general situation --Abstract, page ii

Examining the Relationship Between Sleep and Obesity Using Subjective and Objective Methods

The increasing prevalence of overweight and obese individuals in the United States makes it imperative to study the various causal factors of obesity. Overweight and obesity are typically thought to be caused by an energy imbalance and a majority of research efforts today focus on studying strategies using diet and physical activity to reduce obesity. Unfortunately, despite decades of effort the struggle with obesity continues for many. Other putative causes of obesity such as sleep quantity and quality need to be further explored. With the causes of obesity being multifaceted, it is important to look beyond energy imbalance and find new clues for solving the obesity puzzle. In order to explore the relationship between obesity and sleep, we have designed two studies and will explore this relationship in both prospective and retrospective ways. In the first prospective study, we compare sleep, body weight, and physical activity in children and adults using both objective and subjective tools. There is extensive evidence showing familial relationships with obesity. Sleep patterns and habits may also have ties to the family. Our first objective of the study is to compare sleep amounts in children and adults using these methods. Our second objective is to explore the relationship between sleep amount and body adiposity in the families. We will compare two new objective measures of sleep with a subjective method (sleep log). We hypothesized that the sleep assessment tools will report similar sleep amounts in children and adults. In our second study, we retrospectively examined sleep across the life cycle in females including women who are pregnant. This was a cross-sectional study. We used an objective measure to compare bed times, wake times, and sleep amounts in pregnant compared to non-pregnant women. We hypothesize, that pregnant females will have shorter sleep duration, especially at the later measurement period of 35 weeks gestation, compared to non-pregnant females due the added physical discomfort of pregnancy. This thesis will begin with a literature review focused on obesity, sleep, body composition assessment, physical activity assessment, and sleep assessment. The following sections include the family study manuscript and the female study manuscript each of which includes an abstract, introduction, methods, data analysis, results, and discussion for each manuscript. Following the manuscripts are the conclusions, appendices, references, and acknowledgements

Performance Optimization Over Wireless Links With Operating Constraints

Wireless communication is one of the most active areas of technological innovations and groundbreaking research ranging from simple cellular phones to highly complex military monitoring devices. The emergence of radios with cognitive capabilities like software defined radios has revolutionized modern communication systems by providing transceivers which can vary their output waveforms as well as their demodulation methods. This adaptability plays a pivotal role in efficient utilization of radio spectrum in an intelligent way while simultaneously not interfering with other radio devices operating on the same frequency band. Thus, it is safe to say that current and future wireless systems and networks depend on their adaptation capability which in turn presents many new technical challenges in hardware and protocol design, power management, interference metrics, distributed algorithms, Quality of Service (QoS) requirements arid security issues. Transmitter adaptation methods have gained importance, and numerous transmitter optimization algorithms have been proposed in recent years. The main idea behind these algorithms is to optimize the transmitted signals according to the patterns of interference in the operating environment such that some specific criterion is optimized. In this context, the objective of this dissertation is to propose transmitter adaptation algorithms in conjunction with power control for wireless systems focusing on performance optimization based on operating constraints. Specifically, this dissertation achieves joint transmitter adaptation and power control in the uplink and downlink of wireless systems with applications to Multiple-Input-Multiple-Output (MIMO) wireless systems and cognitive radio networks. In addition, performance of the proposed algorithms are evaluated in the context of fading channels, taking into consideration the time-varying nature of wireless channels

Is Financial Performance of Airline Companies Conditional to the Financial Education and Relevant Experience of Board of Directors?

Numerous variables, particularly the members of the board of directors (BOD), affect the financial results of airline corporations. This study looks how the financial education and relevant work experience of board members, if any, affect the operating results of airline corporations in terms of accounting and stock market performance. The study based on quantitative information from 20 international airlines for seven years. The study utilized multivariate OLS regression approach for analyzing the impact of board attributes on the corporation's key financial performance indicators: Return on Capital Employed (ROCE), Return on Assets (ROA), Earnings Per Share (EPS), stock price appreciation, total risk, and systematic risk. The results indicate positive impact of financial education on ROCE, however, the impacts on other performance measures such as ROA, and EPS were minimal. It was also found that board size and board experience negatively impacted financial performance because bigger and more experienced boards may restrict flexibility and decisiveness in a dynamic setting, such as aviation. The analysis indicates that although financial training helps in capital resource distribution and utilization, there are diminishing returns due to superfluous experience, or size of the board, which may harm firm outcomes. These pieces of advice are useful for crafting policies around board construction in the airline sector, proving that financial knowledge is just as important as industry knowledge

Study of Doping Phenomena in Functional Materials

The disruptive technologies that are currently emerging across the semi-conductor and electronics industries demand the need for a continual focus on decreasing the size of integrated circuits and renewable energy technology devices. To support this demand requires comprehensive research into understanding the functional properties of materials at an atomic level across a three-dimensional space. These functional properties of materials originate from atomic level properties such as structural, optical and electronic properties, all of which can be modified to optimise the functionality of a material. This is the reason why these atomic level properties were comprehensively studied and reported in this thesis. The introduction of atomic level impurities, via the phenomena of doping, has helped to modify the structural, optical and electronic properties of the materials investigated in this thesis. An insight into the effect and potential that high temperature solid-state doping can bring towards improving the functional properties of three materials namely titania-rutile (single crystal substrates), titanates (powders) and Magnesium Silicon Nitrides MgSiN2 (powders), were gained from the experiments and results reported in this thesis. NB: titanates studied include sodium and potassium hexatitanates, sodium trititanate and caesium titanate. Chapters 3-8 of this thesis were written with a specific focus on the spatial arrangement of dopant atoms (such as B, C, S and N) introduced into photocatalytic titania-rutile and the associated influence it has on bonding, diffusion behaviours as well as structural and electronic properties. The insight gained about these properties of titania-rutile are essential when working on an industrial scale to optimise the performance of renewable energy devices, or to at least match with that of fossil fuels. The choice of anionic dopant introduced into the titania-rutile can help to vary the structural or electronic properties in titania-rutile. Additionally, the unit cell structure that determines the surface and bulk structure of the titania-rutile single crystal substrate that was chosen was observed to also help modify the structural or electronic properties. While the carbon, sulphur and nitrogen anions were predominantly incorporated as surface dopants in titania-rutile, this was not the case with boron anions, which also showed results that were dependent on the orientation of the titania-rutile. Boron incorporation in (110)-titania-rutile led to the formation of a TiBO3 surface layer, approximately 120 nm thick as per XPS data. This TiBO3 layer, as per XRD data, is epitaxially arranged on the rutile (110) surface along the (108), (118) and (018) planes. While this layer was also seen on the rutile (100) surface, no XRD evidence of TiBO3 was found with the rutile (001) surface. As well as observing a shift in the XPS valence band onset, the emergence of new states and O2p orbital mixing was also observed upon anion incorporation into rutile. This study, reporting the structural and electronic effects observed as a result of doping, will be crucial when working with photocatalysts that are widely studied for the water splitting process, used to produce hydrogen, which is a ‘clean’ energy fuel. The main insight gained from chapter 9 is about making use of the structure of titanate materials (e.g. in open layered and tunnelled titanates) as a scaffold, to control the spatial distribution of any given dopant. This is particularly relevant when the material being investigated is in its powdered form, with no well-defined surface or a bulk. Chapter 9 was written with a specific focus on the effect of doping temperature on the location of the incorporated nitrogen dopant (aka. structural properties), electronic and optical properties in the open layered and tunnelled titanates. While these relationships are widely reported in the literature already, the challenge that this study addresses are about carrying out nitrogen doping at three different temperatures in the same system to ensure the same ammonia flow rate, which is a parameter that is often very challenging to reproduce. This ensures reproducibility of results and therefore reliability in the conclusions. Also, this study is also more comprehensive than that reported in literature the and discusses samples that are fully characterised. The preferential incorporation of nitrogen into the Ti-O-Ti bonds than the Na-O-Ti bonds was observed in the tunnelled titanates, Na2Ti6O13 and K2Ti6O13, and (not in the open layered titanates Na2Ti3O7 and Cs0.68Ti1.825O4), is potentially what led to the creation of Ti3+ defects as observed in their optical absorption spectrum. The resulting Ti 3d and N 1s states observed in the XPS valence band spectrum is potentially what caused the observed band gap narrowing. The modification of the electronic, optical and structural properties of the titanates using nitrogen doping can be used to optimise the functionality of titanates e.g. when it is used as photocatalysts or as battery materials. The main insight gained from chapter 10 is about exploring the alternative material that can replace the expensive aluminium nitride, which is known to be a promising substrate material with ideal thermal conductivity and minimal dissipation of heat. This was done by studying the change in structural properties including associated unit cell volume. The effect of the addition of varying amounts of aluminium as a dopant into the MgSiN2 structure, helped to find that the phase transformation from MgSiN2 to AlN-wurtzite structure is observed between 30% and 50% aluminium dopant introduction, as per XPS and XRD. While the doubling of the magnesium reactant mass led to a single phase MgSiN2, it can potentially affect particle size properties, as hinted by the XRD peak broadening observed. Increasing the aluminium content to above 50% led to unit cell volume contraction as Al3+ ions are smaller than the lattice Mg2+ ions they are substituting. These findings can help gain an understanding of the fundamental chemistry underpinning the development of cheaper, alternative materials for any applications

ZraP is a periplasmic molecular chaperone and a repressor of the zinc-responsive two-component regulator ZraSR

The bacterial envelope is the interface with the surrounding environment and is consequently subjected to a barrage of noxious agents including a range of compounds with antimicrobial activity. The ESR (envelope stress response) pathways of enteric bacteria are critical for maintenance of the envelope against these antimicrobial agents. In the present study, we demonstrate that the periplasmic protein ZraP contributes to envelope homoeostasis and assign both chaperone and regulatory function to ZraP from Salmonella Typhimurium. The ZraP chaperone mechanism is catalytic and independent of ATP; the chaperone activity is dependent on the presence of zinc, which is shown to be responsible for the stabilization of an oligomeric ZraP complex. Furthermore, ZraP can act to repress the two-component regulatory system ZraSR, which itself is responsive to zinc concentrations. Through structural homology, ZraP is a member of the bacterial CpxP family of periplasmic proteins, which also consists of CpxP and Spy. We demonstrate environmental co-expression of the CpxP family and identify an important role for these proteins in Salmonella's defence against the cationic antimicrobial peptide polymyxin B