Enhancing Single Walled Carbon Nanotube Deposition For The Study Of Extracellular Analytes

Extracellular signaling is a dynamic process responsible for coordinating large scale biological processes. As such, understanding extracellular signaling is important to our determination of normal function and pathophysiological development. High resolution spatial and temporal information are critical to completely understanding these processes. Unfortunately, current methods of detection are lacking in either spatial or temporal resolution of extracellular products, limiting researchers’ ability to understand complex biological processes. A new group of sensors based on fluorescent single walled carbon nanotubes (SWNT) have shown the potential to provide both high quality spatial and temporal resolution for the sensing of analytes. However, while SWNT has already been used extensively as an intracellular probe, it has seldom been used for intercellular monitoring. In the few instances that SWNT has been used to form extracellular sensor arrays the deposition method has relied on electrostatic or non-specific interactions and is not well characterized. Herein a new method of SWNT deposition based on the avidin-biotin bond was developed, where biotin activity was imparted to SWNT via coupling to its DNA wrapping and avidin was covalently immobilized on the surface of a glass slide. The method of SWNT immobilization produced a twofold enhancement in SWNT deposition over the current standard without negatively impacting SWNT spectral properties, distribution, response time, or degradation rates. These results indicate the effectiveness of this method for increasing SWNT deposition and provide a simple pathway for enhancing the deposition of DNA-SWNT complexes. Advisor: Nicole M. Iverso

Enhancing Single Walled Carbon Nanotube Deposition For The Study Of Extracellular Analytes

Extracellular signaling is a dynamic process responsible for coordinating large scale biological processes. As such, understanding extracellular signaling is important to our determination of normal function and pathophysiological development. High resolution spatial and temporal information are critical to completely understanding these processes. Unfortunately, current methods of detection are lacking in either spatial or temporal resolution of extracellular products, limiting researchers’ ability to understand complex biological processes. A new group of sensors based on fluorescent single walled carbon nanotubes (SWNT) have shown the potential to provide both high quality spatial and temporal resolution for the sensing of analytes. However, while SWNT has already been used extensively as an intracellular probe, it has seldom been used for intercellular monitoring. In the few instances that SWNT has been used to form extracellular sensor arrays the deposition method has relied on electrostatic or non-specific interactions and is not well characterized. Herein a new method of SWNT deposition based on the avidin-biotin bond was developed, where biotin activity was imparted to SWNT via coupling to its DNA wrapping and avidin was covalently immobilized on the surface of a glass slide. The method of SWNT immobilization produced a twofold enhancement in SWNT deposition over the current standard without negatively impacting SWNT spectral properties, distribution, response time, or degradation rates. These results indicate the effectiveness of this method for increasing SWNT deposition and provide a simple pathway for enhancing the deposition of DNA-SWNT complexes. Advisor: Nicole M. Iverso

Preliminary design of two Space Shuttle fluid physics experiments

The mid-deck lockers of the STS and the requirements for operating an experiment in this region are described. The design of the surface tension induced convection and the free surface phenomenon experiments use a two locker volume with an experiment unique structure as a housing. A manual mode is developed for the Surface Tension Induced Convection experiment. The fluid is maintained in an accumulator pre-flight. To begin the experiment, a pressurized gas drives the fluid into the experiment container. The fluid is an inert silicone oil and the container material is selected to be comparable. A wound wire heater, located axisymmetrically above the fluid can deliver three wattages to a spot on the fluid surface. These wattages vary from 1-15 watts. Fluid flow is observed through the motion of particles in the fluid. A 5 mw He/Ne laser illuminates the container. Scattered light is recorded by a 35mm camera. The free surface phenomena experiment consists of a trapezoidal cell which is filled from the bottom. The fluid is photographed at high speed using a 35mm camera which incorporated the entire cell length in the field of view. The assembly can incorporate four cells in one flight. For each experiment, an electronics block diagram is provided. A control panel concept is given for the surface induced convection. Both experiments are within the mid-deck locker weight and c-g limits

Ground‐based measurements of NOx and total reactive oxidized nitrogen (NOy) at Sable Island, Nova Scotia, during the NARE 1993 summer intensive

Measurements of NO, NO2, and total reactive oxidized nitrogen (NOy) were added to ongoing measurements of aerosols, CO, and O3 at Sable Island (43°55′N, 60°01′W), Nova Scotia, during the North Atlantic Regional Experiment (NARE) 1993 summer intensive. Ambient levels of NOx and NOy were found to be highly variable, and elevated levels can be attributed to the transport of polluted continental air or presumably to relatively fresh emissions from sources upwind (e.g., ship traffic). The median values for NOx and NOy are 98 and 266 parts per trillion by volume (pptv), respectively. A multiday pollution episode occurred during which elevated NOx and NOy were observed with enhanced levels of O3, CO, and condensation nuclei. Air masses of recent tropical marine origin characterized by low and constant levels of O3 and CO were sampled after Hurricane Emily. The correlation between ozone and CO is reasonably good, although the relation is driven by the single pollution episode observed during the study. The correlation of O3 with NOy and with NOy‐NOx is complicated by the presumed NOy removal processes in the marine boundary layer. Examination of the radiosonde data and comparisons of the surface data with those obtained on the overflying aircraft provide clear indications of vertical stratification above the site

Special Libraries, April 1952

Volume 43, Issue 4https://scholarworks.sjsu.edu/sla_sl_1952/1003/thumbnail.jp

The doctoral research abstracts. Vol:6 2014 / Institute of Graduate Studies, UiTM

Congratulations to Institute of Graduate Studies on the continuous efforts to publish the 6th issue of the Doctoral Research Abstracts which ranged from the discipline of science and technology, business and administration to social science and humanities. This issue captures the novelty of research from 52 PhD doctorates receiving their scrolls in the UiTM’s 81st Convocation. This convocation is very significant especially for UiTM since we are celebrating the success of 52 PhD graduands – the highest number ever conferred at any one time. To the 52 doctorates, I would like it to be known that you have most certainly done UiTM proud by journeying through the scholastic path with its endless challenges and impediments, and by persevering right till the very end. This convocation should not be regarded as the end of your highest scholarly achievement and contribution to the body of knowledge but rather as the beginning of embarking into more innovative research from knowledge gained during this academic journey, for the community and country. As alumni of UiTM, we hold you dear to our hearts. The relationship that was once between a student and supervisor has now matured into comrades, forging and exploring together beyond the frontier of knowledge. We wish you all the best in your endeavour and may I offer my congratulations to all the graduands. ‘UiTM sentiasa dihati ku’ Tan Sri Dato’ Sri Prof Ir Dr Sahol Hamid Abu Bakar , FASc, PEng Vice Chancellor Universiti Teknologi MAR

Special Libraries, April 1952

Volume 43, Issue 4https://scholarworks.sjsu.edu/sla_sl_1952/1003/thumbnail.jp

Integration of microwave heating with continuously operated milli-reactors for fine chemical synthesis

Major efforts in the research field of microwave assisted organic synthesis have demonstrated the specific benefits associated with the use of microwave irradiation such as selective and rapid heating of the reaction mixture. In many case studies, these benefits eventually lead to a significant enhancement in the production rates. Therefore, microwave assisted flow synthesis can be an interesting alternative for fine chemical production in conventionally heated batch reactors. However, realization of microwave assisted flow synthesis at kilogram scale requires a proper design of tubular reactors integrated with the microwave heating source, i.e. the cavity. The design of these reactors should primarily be able to overcome the limitations by the penetration depth of the microwaves, i.e. ¿0.013 m. Moreover, operation based on microwave heating should allow accurate temperature control by precise tuning and quantification of the microwave energy distribution. Therefore, being case specific, design efforts are necessary for the microwave setup as well as for the reactor configuration. Heating in monomode microwave equipment is energy efficient and fast in comparison to heating in multimode microwave equipment. State-of-the-art microwave cavities, however, lack in providing important functionalities, such as a predictable electric field pattern, tuning facility, detailed energy distribution and possibilities for modular scale-up. A waveguide type monomode microwave cavity in combination with the short circuit, stub tuners, and isolators can provide the aforementioned functionalities for continuously operated reactors. This type of microwave setup allows an accurate elaboration of energy balances for efficient and uniform heating. Additionally the use of multiple cavities connected to a single microwave generator via a main waveguide permits modular scale-up. The dielectric properties (i.e. dielectric constant and dielectric loss) of a microwave absorbing load (e.g. reaction mixture/solvent) are significantly dependent on temperature. As a consequence, microwave absorption, which involves interaction of the electromagnetic field with the applied load, is a recurring process. Therefore, detailed understanding of the dielectric property change with temperature is a prerequisite for a proper design of the load to be used under stop-flow (batch) and continuous-flow conditions. For stop-flow conditions, the highest heating efficiency (70 %) is observed for a load diameter equal to and larger than half of the wavelength of the microwaves in the liquid medium. For continuous-flow conditions, the heating efficiency increases linearly with the load diameter. However, microwave leakage above the propagation diameter (i.e. half wavelength) limits further increase of the load diameter in continuous operation. The high energy intensity of the focused electromagnetic field in case of waveguide type microwave cavities makes an efficient and controlled continuous operation difficult, especially when a strong microwave absorbing load (e.g. ethanol) is present. In cases, such as the reaction of ethanol and acetic acid to produce ethyl acetate over a strong acid ion-exchange resin, a milli reactor-heat exchanger combination with a co-current flow of a microwave transparent solvent (coolant) can be a solution. Here, rapid volumetric heating to the reaction temperature can be achieved by microwaves before the reaction mixture enters into the catalyst bed. Additionally, the coolant not only limits overheating of the reaction mixture but also permits heat integration, resulting in extended reactor lengths and efficient heating (i.e. 96 %). However, stagnancy in the flow of the microwave absorbing load results in a poor convective heat transport. As a consequence, stagnant layer formation caused either by any insertion (of system components, such as fiber optic sensors) or at the reactor walls, yields higher temperatures and lower microwave energy dissipation regions. One of the promising approaches for scaling microwave assisted flow synthesis is numbering up. The numbering up approach is based on parallelization of tubular structured reactors with a channel diameter in the millimeter range. The performance of such a configuration is evaluated by a multi-tubular milli-reactor/heat exchanger system with a thin Cu film on the inner walls of the reactor tubes. The thin Cu film provides uniform microwave absorption and it improves the production rate by acting as a heated catalytically active surface, as demonstrated in the synthesis of 1,3-diphenyl-2-propynyl-piperidine from benzaldehyde, piperidine, and phenylacetylene. Controlled selective heating of the thin Cu film is achievable by using a counter-current flow of a microwave transparent coolant (toluene). The coolant flow avoids Cu burning and reduces leaching, consequently improving the steady state catalytic performance of the Cu coated reactor tubes. Higher temperatures, i.e. at least 100 K higher than the bulk liquid, are achievable at the locus of the reaction, i.e. the catalyst surface, purely due to selective microwave heating. Another approach to realize higher production rates is utilization of multiple microwave cavities in series. In this approach, the process stream is taken from one cavity to the next where the process efficiency is well optimized over each consecutive cavity. Transient operation through each optimized cavity and utilization of multiple cavities in series increases conversion and consequently results in higher production rate. Additionally, known kinetics allows estimation of the production rate for each additional cavity in the series. This approach of scale-up is possible at minimized grid to applicator losses by connecting multiple cavities to a single microwave generator via a main waveguide. Scale-up approaches based on parallelization of tubular structured reactors as well as on utilization of multiple microwave cavities in series were found to be successful. Application of microwaves as a process intensification tool, especially in the case of organic synthesis, is very attractive for liquid-solid reactions, where the solid is the selectively (microwave) heated catalyst

Merging storm water management with stream rehabilitation: Greensboro’s Lake Daniel pilot project

In spite of progress controlling discharges of industrial pollutants from discrete points, many urban drainage basins continue to suffer from heavy loads of sediment and pollutants in the form of storm water runoff from lawns, streets, driveways, parking lots, and other dispersed sources (Arnold et al., 1993; Riley, 1992; Ferguson 1991; Horak, 1988). Altered geomorphic and soil conditions, leaking or broken sewer lines, and structural responses to flooding also contribute to the degraded natural condition of many urban streams. City governments and local environmental groups are attempting to restore natural vitality to such streams and wetlands through cooperative, integrated efforts to reduce storm water borne pollution (DeWitt, 1994). Stream rehabilitation efforts can be merged with the National Pollutant Discharge Elimination System (NPDES). Under authority of the Water Quality Act of 1987 NPDES requires local governments to devise plans for -reducing sediment and pollutants carried by storm water runoff directly to streams or water treatment plants. State and local governments are also providing grants to fund community-based stream restoration projects that serve multiple goals, including storm water management (Riley, 1992). Greensboro, North Carolina, exemplifies the process of meeting the NPDES requirements to plan for storm water management with local public involvement. This article reviews the parallel histories of stream greenway rehabilitation and storm water management and describes the ongoing process of merging the two goals in a Southern Piedmont context