The main objective of this report is to demonstrate novel engineering technologies to investigate regulatory mechanisms of systems immunology in a time-dependent and high-throughput manner. Understanding of immune system behavior is crucial for accurate prognosis of infections and identification of diseases at early stage. An ultimate goal of biomedical engineering is to develop predictive models of immune system behavior in tissue, which necessitates a comprehensive map of dynamic (time-dependent) input-output relationships at the individual cell level. Traditionally, biochemical analysis on the cell signaling is obtained from bulky cell ensembles which average over relevant individual cell response. The response consists firstly of signaling protein (cytokine) secretions which are released during a disease state and which are used to activate the immune system to respond to the disease. We investigate the cytokine secretion dynamics of a single immune cell in response to the stimulant using automated and comprehensive optofluidic platforms. These platforms enable survival and manipulation of single cells in compartments having compatible sizes with cells as well as provide precise control over the type, dose and time-course of the stimulant. The cytokine secretion dynamics of single cell are typically explained by measuring the types, rates, frequencies and concentrations of various cytokines. For the quantitative measurements, label free localized surface plasmon resonance (LSPR) based biosensor can be integrated within the microfluidic device. Microfluidic channels can confine secreted cytokines in compartments, minimize dilution effects and increase detection sensitivity for label free plasmonic biosensing. The direct application of LSPR to in-situ live cell function analysis is still in its infancy and use of such in-situ, real time, and label free biodetection will effortlessly provide high-throughput quantitative bioanalysis for understanding immune system behavior.

The paper describes a novel method of exfoliated graphite synthesis. The method includes synthesis of graphite intercalation compound in liquid ammonia medium and subsequent intercalate decomposition with graphite exfoliation. Influence of the experimental parameters on the morphology and structure of the exfoliated graphite is shown. Comparison of the developed exfoliation method to the high-temperature oxidation-reduction method used in industrial scale nowadays is presented. A number of application areas for the synthesized exfoliated graphite are described.

There is pressing need in computation of a universal phase change memory consolidating the speed of RAM with the permanency of hard disk storage. A potentiated scanning tunneling microscope tip traversing the soliton separating a metallic, ABA-stacked phase and a semiconducting ABC-stacked phase in trilayer graphene has been shown to permanently transform ABA-stacked regions to ABC-stacked regions. In this study, we used density functional theory (DFT) calculations to assess the energetics of this phase-change and explore the possibility of organic functionalization using s-triazine to facilitate a reverse phase-change from rhombohedral back to Bernal in graphene trilayers. A significant deviation in the energy per simulated atom arises when s-triazine is adsorbed, favoring the transformation of the ABC phase to the ABA phase once more. A phase change memory device utilizing rapid, energy-efficient, reversible, field-induced phase-change in graphene trilayers could potentially revolutionize digital memory industry.

Pellets made of pure sodalite blended with commercial glass frit and pellets made of sodalite, glass frit and a mixture of chloride salts, synthesized through dry pressing and subsequent thermal treatment, were evaluated as a potential matrix for confinement of spent chloride salts coming from pyroprocesses. The sodalite pellets were leached at 23°C and 90°C for 28 days, according to the ASTM C1220-10 procedure. Normalized release rates were estimated for the following elements: Li, Na, Al, Si, K, Rb, Cs, Sr, Ba, La, Nd and compared with literature results. SEM investigations, carried out before and after the leaching tests, show dissolution and re-precipitation phenomena at 90°C.

Measurements of the induced acoustoelectric (IAEC) current in graphene subjected to a surface acoustic wave (SAW) discovered a quantisized character of acoustoelectric current at low bias voltage (Vbias) . The quantisized nature of IAEC has been obtained in all measurements as a result of interaction of SAW and an applied an external electric field. The acoustoelectric currents were studied near the point of electrical neutrality at room temperature. Raman spectra of graphene under the in-situ SAW influence and at an external electric field bias are presented.

An experimental investigation to verify the suitability of MoOx as the hole collection layer for a-Si:H based thin film photovoltaic cell is carried out. The photovoltaic cell investigated has the structure of MoOx (hole collection layer) / intrinsic a-Si:H (photoactive layer) / phosphorus doped a-Si:H (electron collection layer) / Ag (back reflector electrode); all deposited in that order onto an Asahi glass (type U) substrate, which is also acting as the transparent front electrode for the cell. The effects of different post deposition annealing temperatures are investigated. The highest efficiency values are obtained for the cells annealed at 120°C. For the photovoltaic cell with 100 nm thick photoactive layer, the highest efficiency is measured to be 6.46 % with an open current voltage (Voc) of 827 mV and a short current density of (Jsc) of 10.44 mA/cm2. For the photovoltaic cell with 300 nm thick photoactive layer, the highest efficiency is measured to be 7.93 % with Voc of 818 mV and Jsc of 13.24 mA/cm2. The efficiency measurements are carried out under AM1.5 test conditions. Jsc values are corrected according to the external quantum efficiency measurements of the cells in the AM1.5 photovoltaic spectrum region between 270 nm and 800 nm. Compared to the reference cell with boron doped μ-SiOx layer acting as the hole collection layer, the cell with MoOx hole collection layer has similar FF, lower Voc, higher Jsc for wavelength up to the green light region of the AM1.5 spectrum and lower Jsc for the longer wavelengths.

Bandgap energies of the group III-V quaternary alloy semiconductor, cubic AlxGa1−x NyAs1−y , were calculated by means ofthe dielectric method. While only GaN and GaAs are considered to be directtransition type among the four constituent binary compounds of this quaternaryalloy system, the calculation results show that the bandgap energy range coveredin the direct transition regime of this alloy system was further extended to thehigher energy side of GaN as well as to the lower energy sides of GaAs. Theextension to the higher energy side was attributed to the larger direct bandgapof AlN. On the other hand, the extension to the lower energy side was caused bythe large bowing in the bandgap energy between group III nitrides and arsenides.Calculations under lattice matching to Si and GaAs are also presented.

Glass-ceramics were developed initially for the immobilization of miscellaneous Pu-residues at the UK’s Sellafield site from which it was uneconomic to recover Pu for reuse. Renewed interest in the immobilization of a portion of the UK PuO2 stockpile has led to glass-ceramics being evaluated for bulk Pu immobilization. The Nuclear Decommissioning Authority (NDA) in the UK have proposed hot isostatic pressing (HIP) as a potential consolidation technique for the processing of these wasteforms. In this study, zirconolite based glass-ceramics were investigated to determine an optimum formulation. The yield of zirconolite is shown to vary with glass composition and glass fraction, such that a higher Al content favours zirconolite formation. The sample preparation process is discussed to highlight the importance of a high temperature heat-treatment during sample preparation to achieve high quality HIPed wasteforms.

Pitting and localized corrosion can occur under various conditions and accelerate the subsequent cracking and the failure of a component. Pit-to-crack transition is considered a critical transition process and has a significant impact on the total lifetime of a component. In this study, an alternating current potential drop (ACPD) system is built and applied the detection of the pit-to-crack transition. The results show that the ACPD system is capable and sensitive to crack initiation and that the sensitivity increased with increased frequency. Crack initiation sites from pits are characterized and discussed.

GaN has emerged as the material of choice for advanced power amplifier devicesfor both industrial and defense applications but near-junction thermal barriersseverely limit the inherent capability of high-quality GaN materials. Recent“embedded cooling” efforts, funded by Defense AdvancedResearch Projects Agency Microsystems Technology Office (DARPA-MTO), havefocused on reduction of this near-junction thermal resistance, through the useof diamond substrates and efficient removal of the dissipated power withconvective and evaporative microfluidics. An overview of the accomplishments ofthe DARPA Near-Junction Thermal Transport (NJTT) program and recent results fromthe on-going DARPA Intra-Chip Embedded Cooling (ICECool) program are provided.It is shown that growth or bonding of diamond to GaN epitaxy has enabled a3-5× increase in power handling capability per transistor unit area,while use of microfluidic cooling has enabled heat fluxes of 30kW/cm2 at the transistor level and 1 kW/cm2 at thedie-level, for a 3-6× improvement in the total RF output power of GaNpower amplifiers. These demonstrations provide near-term validation of the largeimprovement in output power gained through embedded cooling and confirm thepotential for well above a 6× improvement in GaN power amplifier outputpower to the electrical, rather than thermal, limits of GaN.