Fast estimation of RL‐loaded microelectronic interconnections delay for the signal integrity prediction

This article presents a modelling method of the signal delays induced by microelectronic interconnections regarding RL impedance load. The method proposed is based on the RLC model of the transmission lines (TL) extracted from the equivalent S parameters. Formulation for estimating the interconnection propagation delay is established according to the behaviour of the TL unit step responses. The second order model is validated with a microstrip interconnect prototype with simulations and measurements in frequency and time domains. The developed propagation delay model was validated with SPICE computations. For that, a transient simulation was performed by considering input signals corresponding to high‐speed data of some Gbits/s. Then, accurate results were found for interconnections with different lengths in order of millimetre and also by varying the load values. It was shown that the computed 50% propagation delays present of relative errors about 5%. Copyright © 2011 John Wiley & Sons, Ltd.     

Active Microwave Circuit With Negative Group Delay

In this letter, we report on the design, simulation and implementation of an active negative group delay circuit that operates at 1 GHz with a group delay and a gain, respectively, around 2 ns and 2 dB. Analytical formulas are proposed to demonstrate that the adopted topology is able to simultaneously achieve negative group delay (NGD) and gain while fulfilling active device constraints. The theoretical and simulated results are both validated by frequency measurements of a two-stage active microwave circuit.     

Dynamic interface velocity for junction characterization

A dynamic velocity at the n-p junction interface has been introduced. Solar cell structures have been used as diode models. The relationship of the dynamic velocity with the technological parameters of solar cells and with the junction operating conditions has been considered. The variations of this dynamic velocity with the potential at the junction point out the influence of the base doping level and of the base width, and allow to differentiate the nature of the cell back contact.     

Heat capacity studies of ThP and UP0.5As0.5 solid solution. Reanalyzing UP data

The specific heats of ThP and the solid solution UP_0.5As_0.5 have been measured in the temperature range 5–300 K. While ThP has a regularC _p (T) behavior, the mixed compound exhibits several low-temperature anomalies. An analysis of the experimental data for UP_0.5As_0.5 and reanalysis of previously published heat capacity results for UP have been performed. The temperature dependence of the magnetic entropy, which at 300 K reaches a value close toR ln 4 for both species, confirms the U³⁺ state for uranium atoms in these compounds. The value of the electronic heat capacity coefficient _p in the paramagnetic state has also been extracted from the experimental data. It is far smaller than the respective low-temperature value (0).     

The effects of pharmaceuticals on the regeneration of the cnidarian, Hydra attenuata

The Hydra attenuata regeneration assay was used to identify the teratogenic potential of 10 pharmaceuticals identified in effluent from a large city wastewater treatment plant (WWTP). Three types of solvents were used to solubilise the pharmaceuticals (DMSO, acetone and ethanol), at concentrations determined to have no significant effect on measured endpoints. On the one hand, regeneration was significantly inhibited at (nominal) concentrations of 1, 5 and 1 mg/L for gemfibrozil, ibuprofen and naproxen respectively and at the higher concentration of 50 mg/L for bezafibrate and trimethoprim. On the other hand, carbamazepine and the antibiotics sulfapyridine, oxytetracycline and novobiocin significantly increased regeneration at 25, 5, 50 and 50 mg/L respectively. Relatively high IC50 values of 0.9, 3.84, 4.9 and 22.5 mg/L were calculated for gemfibrozil, ibuprofen, naproxen and bezafibrate, respectively. However when subjected to tier two toxicity assessment under EU regulatory guidance using environmentally relevant concentrations a MEC/PNEC value>1 was calculated for gemfibrozil, ibuprofen and naproxen indicating teratogenic potential and the necessity for further tier three assessment. A toxicity index (TI) was also calculated using three different techniques, with TI values>3 (indicating teratogenic potential) found for gemfibrozil, ibuprofen, naproxen and bezafibrate and >1 (indicating a weak teratogenic potential) found for carbamazepine. These results are discussed in the context of their environmental relevance and toxic potential.     

Prospects use of hybrid layered double hydroxides‐polyacrylamide as controlled release media for antibiotic molecules

Some controlled‐release media containing two commercial antibiotic molecules, viz. Amoxicillin (AMX) and Ampicillin (AMP), were prepared using layered double hydroxides (LDH) intercalated and extended by polyacrylamide. The polycarylamide was prepared in situ by polymerization of acrylamide monomer intercalated in the interlayers of LDH. The LDH‐polyacrylamide‐antibiotic hybrid nanocomposites were characterized by various techniques like Fourier transform infrared (FT‐IR), powder X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FE‐SEM). The results from these characterizations have shown the successful incorporation of the antibiotics in the interlayers and provided important information regarding their interlayer structure. The nanocomposites showed increased thermal stability in TGA. The loading of antibiotic in the PAM/Mg‐Al nanocomposite was found to be 36.33% for AMX and 52.38% for AMP. The improved antibacterial activity of hybrid nanocomposite was evaluated against Escherichia coli using the wells diffusion technique. The aliquot samples in agar media drug release study were found to be highly effective against microorganisms. The sustained release of antibiotic drug from the hybrid nanocomposite was also verified. The release rate at pH 7.4 phosphate buffer was found slower than that at pH 4.6. It can be concluded that hybrid nanocomposites of LDH extended by in situ polymerized acrylamide are very suitable materials to host different antibiotics and their controlled release. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45442.     

Tessellation of Chiral‐Nematic Cellulose Nanocrystal Films by Microtemplating

In biological architectures, material properties are optimized by the hierarchical structuring of components with a multiscaled order, from the nano‐ to the macroscales. Such designs enable, for instance, programmed yield points that maximize toughness. However, research efforts in biomimetic materials have focused on the assembly of nano‐ or macrostructures individually. In this study, high strength cellulose nanocrystals (CNCs), assembled into chiral‐nematically ordered structures, are tiled into a higher level, macro‐sized, architecture by topographical templating. As templates, two meshed architectures with distinct feature sizes are evaluated, and the optomechanical properties of the resulting films are compared to featureless, flat, CNC films. Controlling capillary stresses arising during CNC assembly is shown to enable control over the orientation of the chiral‐nematic director across the topography of the template. Tuning the specific reflections and multiscaled fracture propagation is demonstrated for the microtemplated CNC films. The latter phenomenon contributed to enhancing the toughness of the material through a high tortuosity of fracture propagation in all (x, y, z) directions. The presented findings are expected to pave the way towards the incorporation of current research in cellular metamaterials with the research focusing on the generation of nanoscaled biomimetic constructs.     

Effects of supplemental source of magnesium and inclusion of buffer on ruminal microbial fermentation in continuous culture

Magnesium oxide (MgO) is the most common supplemental source of Mg for dairy cows and a proven ruminal alkalizer when supplemented above NRC (2001) recommendations. However, overfeeding MgO may increase feeding costs, whereas the effects of alternative sources of Mg on ruminal fermentation are not well known. Moreover, it is still unclear if Mg supplementation influences the effects of bicarbonate-based buffers on ruminal fermentation. We aimed to evaluate the effect of Mg source on ruminal fermentation with diets formulated to a final concentration of 0.25% Mg, and to determine if the effect of sodium sesquicarbonate as a buffer varies with the source of Mg. We used 8 fermentors in a duplicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments, by combining 2 factors: (1) Mg source: using either MgO or an alternative source consisting of a blend of CaMg(OH)₄ and CaMg(CO₃)₂ (BLN) and (2) sodium sesquicarbonate buffer inclusion, at 0 or 0.6% of dry matter intake. Based on preliminary tests of reactivity, we hypothesized that BLN plus buffer would allow for greater ruminal pH, acetate molar proportion, and NDF digestibility than diets with MgO or without buffer. Four 10-d periods were completed, where the last 3 d were used for pH measurements and collection of samples for volatile fatty acids (VFA), ammonia (NH₃-N), Mg solubility, N metabolism, and nutrient digestibility. Effects of Mg source (source), sodium sesquicarbonate inclusion (buffer), and their interaction (source × buffer) were tested with the MIXED procedure of SAS (SAS Institute Inc.). We did not find an effect of Mg source on ruminal fermentation variables; however, concentration of soluble Mg in ruminal fluid was greater for MgO compared with BLN. On the other hand, buffer supplementation increased average ruminal pH, acetate molar proportion, and branched-chain VFA molar proportion; tended to increase NDF digestibility; and decreased both area under the curve and time below pH 6.0. An interaction of source × buffer was found for propionate, butyrate, and NH₃-N, the first one decreasing and the 2 others increasing only when buffer was supplemented to the BLN diet. Our results indicate that supplementing Mg with either MgO or BLN promotes similar ruminal fermentation in diets with total concentration of 0.25% Mg. Further evaluations are needed to assess Mg availability and animal performance in dairy cows fed BLN.     

Modeling representative Gen‐IV molten fuel reactivity effects in the ZEPHYR ZPR ‐ LFR analysis

Studies related to severe core accidents constitute a crucial element in the safety design of Gen‐IV systems. A new experimental program, related to severe core accidents studies, is proposed for the zero‐power experimental physics reactor (ZEPHYR) future reactor. The innovative program aims at studying reactivity effects at high temperature during degradation of Gen‐IV cores by using critical facilities and surrogate models. The current study introduces the European lead‐cooled system (ELSY) as an additional Gen‐IV system into the representativity arsenal of the ZEPHYR, in addition to the sodium‐cooled fast reactors. Furthermore, this study constitutes yet another step towards the ultimate goal of studying severe core accidents on a full core scale. The representation of the various systems is enabled by optimizing the content of plutonium oxide in the ZEPHYR fuel assembly. The study focuses on representing reactivity variation from 900°C at nominal state to 3000°C at a degraded state in both ELSY and Advanced Sodium Technological Reactor for Industrial Demonstration (ASTRID) cores. The study utilizes the previously developed calculation scheme, which is based on the coupling of stochastic optimization process and Serpent 2 code for sensitivity analysis. Two covariance data are used: the ENDF 175 groups for ELSY and the Covariance Matrix Cadarache (COMAC) 33 groups for ASTRID. The effect of the energy group structure of the covariance data on the representativity process is found to be significant. The results for single degraded ELSY fuel assembly demonstrate high representativity factor (>0.95) for reactivity variation and for the criticality level. Also, it is shown that the finer energy group structure of the covariance matrices results in dramatic improvement in the representation level of reactivity variations.