ITN Energy Systems (United States)

SUMMARY & CONCLUSIONSAs part of the effort to decarbonize California’s energy infrastructure, there is ongoing research on the effects of hydrogen on the safety and performance of existing natural gas transmission, distribution, and end-use equipment. This paper presents an approach to system modeling for a distribution line and connected central power station based on a real system being tested for hydrogen compatibility. In total, this system covers about two miles of distribution pipe that connects to a central turbine which is expected to be blended with hydrogen. The system model examines the risk of loss-of-containment as well as the potential reduction or loss of functionality that could result from adverse effects of hydrogen on each component. This model is built using the hybrid causal logic method, which allows Bayesian networks to be mathematically related to fault trees and event sequence diagrams.For pipe segments, the increased risk of fatigue and fracture failures is modeled according to the API 579 Level 2 Assessment for crack acceptability. The initial flaw size is taken as an uncertain variable, allowing the probability of failure to be assessed according to the expected distribution of flaw size. The effect of hydrogen on the fracture resistance of the pipe was evaluated using a regression model based on historical experimental testing of commonly used pipeline steels in hydrogen environments. For discrete components, such as valves, the expected failure modes and the baseline failure rates for each mode are determined by published historical failure data. The change in each failure mode is modeled as a relative change in the underlying physical failure mechanisms that are most likely to cause that failure mode. These mechanisms are modeled using data driven or physics-based models, such as the one developed for the reduction in steel fracture toughness, where available. Where such models are not available, expert opinion is used to estimate the relative change in risk. The combination of differing information sources is accomplished using a Bayesian network where the operating conditions of individual components can be set as evidence to obtain the risk of all failure modes for that component.The distribution lines and central plant are each considered as a separate phase of the model, where a failure in the distribution line will result in a loss of functionality for the central plant.

This article discusses about how teaching listening class was implemented in the English practice program during covid-19 pandemic. Descriptive method was applied to find out whether selected material utilized by effective instructional media could meet the learning objective of the English practice program. The result showed that both the intensive and extensive material in listening class could be applied by using some media that can be used during online class by considering both students and instructors’ internet access. The selected online media platform that can replace face-to-face meeting is Google Meet application, while Google Classroom, YouTube, and WhatsApp application are selected to share and submit the class’s assignments. The teacher’s role in engaging the students with particular activities are highlighted.

The capacitance of conducting polymers represents one of the most important material parameters that in many cases determines the device and material performances. Despite a vast number of experimental studies, the theoretical understanding of the origin of the capacitance in conducting polymers remains unsatisfactory and appears even controversial. Here, we present a theoretical method, based on first principle capacitance calculations using density functional theory (DFT), and apply it to calculate the volumetric capacitance of two archetypical conducting polymers: poly(3,4-ethylene dioxythiophene) (PEDOT) and polypyrrole (PPy). Our aim is to achieve a quantitate description of the volumetric capacitance and to provide a qualitative understanding of its nature at the atomistic level. We find that the volumetric capacitance of PEDOT and PPy is ≈100 F cm−3 and ≈300 F cm−3, respectively, which is within the range of the corresponding reported experimental results. We demonstrate that the capacitance of conducting polymers originates from charges stored in atomistic Stern layers formed by counterions and doped polymeric chains. The Stern layers have a purely electrostatic origin, since the counterions do not form any bonds with the atoms of the polymeric chains, and no charge transfer between the counterions and conducting polymer takes place. This classifies the conducting polymers as double-layer supercapacitors rather than pseudo-capacitors. Further, we analyze contributions to the total capacitance originating from the classical capacitance CC and the quantum capacitance CQ, respectively, and find that the latter provides a dominant contribution. The method of calculations of the capacitance developed in the present paper is rather general and opens up the way for engineering and optimizing the capacitive response of the conducting polymers.

The performance of an all-organic paper supercapacitor based on nanocellulose and a conductive polymer was greatly enhanced by incorporating lignin.

Type 1 diabetes (T1D) results from destruction of pancreatic β cells by autoreactive effector T cells. We hypothesized that the immunomodulatory drug alefacept would result in targeted quantitative and qualitative changes in effector T cells and prolonged preservation of endogenous insulin secretion by the remaining β cells in patients with newly diagnosed T1D. In a multicenter, randomized, double-blind, placebo-controlled trial, we compared alefacept (two 12-week courses of 15 mg/wk i.m., separated by a 12-week pause) with placebo in patients with recent onset of T1D. Endpoints were assessed at 24 months and included meal-stimulated C-peptide AUC, insulin use, hypoglycemic events, and immunologic responses. A total of 49 patients were enrolled. At 24 months, or 15 months after the last dose of alefacept, both the 4-hour and the 2-hour C-peptide AUCs were significantly greater in the treatment group than in the control group (P = 0.002 and 0.015, respectively). Exogenous insulin requirements were lower (P = 0.002) and rates of major hypoglycemic events were about 50% reduced (P < 0.001) in the alefacept group compared with placebo at 24 months. There was no apparent between-group difference in glycemic control or adverse events. Alefacept treatment depleted CD4+ and CD8+ central memory T cells (Tcm) and effector memory T cells (Tem) (P < 0.01), preserved Tregs, increased the ratios of Treg to Tem and Tcm (P < 0.01), and increased the percentage of PD-1+CD4+ Tem and Tcm (P < 0.01). In patients with newly diagnosed T1D, two 12-week courses of alefacept preserved C-peptide secretion, reduced insulin use and hypoglycemic events, and induced favorable immunologic profiles at 24 months, well over 1 year after cessation of therapy. https://clinicaltrials.gov/ NCT00965458. NIH and Astellas.

Aiming to apply the multivalency concept to melanoma imaging, we have assessed the in vivo melanocortin type 1 receptor (MC1R)-targeting properties of (99m)Tc(I)-labeled homobivalent peptide conjugates which contain copies of the α-melanocyte-stimulating hormone (α-MSH) analog [Ac-Nle(4), Asp(5), D-Phe(7), Lys(11)]α-MSH4-11 separated by linkers of different length (L(2) nine atoms and L(3) 14 atoms). The MC1R-binding affinity of L(2) and L(3) is significantly higher than that of the monovalent conjugate L(1). Metallation of these conjugates yielded the complexes fac-[M(CO)(3)(k(3)-L)](+) (M is (99m)Tc/Re; 1/1a, L is L(1); 2/2a, L is L(2); 3/3a, L is L(3)), with IC(50) values in the subnanomolar and nanomolar range. The MC1R-mediated internalization of 2 and 3 is higher than that of 1 in B16F1 melanoma cells. Biodistribution studies in melanoma-bearing mice have shown low nonspecific accumulation with a tumor uptake that correlates with IC(50) values. However, no correlation between tumor uptake and valency was found. Nevertheless, 2 displayed the highest tumor retention, and the best tumor to nontarget organ ratios.

The design of a new type of plasmonic ultra-high extinction ratio micropolarizing transmission filter is presented along with an experimental demonstration. A pair of dielectric coated metal gratings couple incident TM polarized light into surface plasmons, which are fed into a central metal-insulator-metal (MIM) waveguide, followed by transmission through a sub-wavelength aperture. Extinction ratios exceeding 10¹¹ are predicted by finite element simulation. Good absolute agreement for both the spectral and polarization response is obtained between measurement and simulations using measured geometric parameters. The filters can be easily fabricated and sized to match the pixel pitch of current focal plane arrays.

An important application of thin-film hydrogenated amorphous silicon (α-Si:H) is infrared detection and imaging with microbolometer focal plane arrays. Key α-Si:H electrical transport properties that influence detector design and performance are resistivity and temperature coefficient of resistance (TCR). These properties have been measured over a wide temperature range for p- and n-type doped α-Si:H thin-films deposited by plasma enhanced chemical vapor deposition using silane as a precursor gas. Resistivity near and above room temperature follows an Arrhenius thermally activated dependence. At low temperatures, resistivity transitions from Arrhenius behavior to a variable range hopping mechanism described by the Mott relation and TCR changes at a slower rate than predicted by thermally activated transport alone. Resistivity and TCR are affected by doping and film growth parameters such as dilution of the silane precursor with hydrogen. Resistivity decreases with dopant concentration for both p-type and n-type dopants. Resistivity and TCR increase with hydrogen dilution of silane. TCR and resistivity are interrelated and optimization of thin-film preparation and processing is necessary to obtain high TCR with resistivity values compatible with readout integrated circuit designs. Such optimization of transport properties of α-Si:H films has been applied to the development of high performance ambient operating temperature (uncooled) microbolometer arrays.

Abstract An increasingly important application of thin film hydrogenated amorphous silicon (α-Si:H) is in infrared detection for microbolometer thermal imaging arrays. Such arrays consist of thin α-Si:H films that are integrated into a floating thermally isolated membrane structure. Among the α-Si:H material properties affecting the design and performance of microbolometers is the microstructure. In this work, Raman spectroscopy is used to study changes in the microstructure of protocrystalline p-type α-Si:H films grown by PECVD as substrate temperature, dopant concentration, and hydrogen dilution are varied. The films exhibit the four Raman spectral peaks corresponding to the TO, LO, LA, and TA modes. It is found that the TO Raman peak becomes increasingly well defined (decreasing line width and increasing intensity), and shifts towards the crystalline TO energy as substrate temperature is increased, H dilution of the reactants is increased, or as dopant concentration is decreased.

We have modeled plasmonic waveguides that support low-loss modes using configurations compatible with metal-oxide-semiconductor devices. Our experimental verification with visible wavelength analogs demonstrates that silicon-based plasmonic modulators are possible.