A continuous-time delta-sigma modulator for 802.11a/b/g WLAN implemented with a hierarchical bottom-up optimization methodology

This paper presents a 3rd-order continuous-time Delta-Sigma modulator with a resolution of 10 bits for a 10 MHz signal bandwidth. It is designed in a standard 0.18 μm CMOS technology and consumes only 6 mW. After the design/selection of the topologies for the integrators, comparator and D/A converters, optimal sizing of the complete modulator was ensured by using a hierarchical bottom-up, multi-objective evolutionary design methodology. With this methodology, a set of Pareto-optimal modulator designs is generated by using Pareto-optimal performance solutions of the hierarchically decomposed lower-level subblocks. From the generated Pareto-optimal design set, a final optimal design is chosen that complies with the specifications for the 802.11a/b/g WLAN standard and has minimal power consumption.     

Pre-Omicron Vaccine Breakthrough Infection Induces Superior Cross-Neutralization against SARS-CoV-2 Omicron BA.1 Compared to Infection Alone

SARS-CoV-2 variants raise concern because of their high transmissibility and their ability to evade neutralizing antibodies elicited by prior infection or by vaccination. Here, we compared the neutralizing abilities of sera from 70 unvaccinated COVID-19 patients infected before the emergence of variants of concern (VOCs) and of 16 vaccine breakthrough infection (BTI) cases infected with Gamma or Delta against the ancestral B.1 strain, the Gamma, Delta and Omicron BA.1 VOCs using live virus. We further determined antibody levels against the Nucleocapsid (N) and full Spike proteins, the receptor-binding domain (RBD) and the N-terminal domain (NTD) of the Spike protein. Convalescent sera featured considerable variability in the neutralization of B.1 and in the cross-neutralization of different strains. Their neutralizing capacity moderately correlated with antibody levels against the Spike protein and the RBD. All but one convalescent serum failed to neutralize Omicron BA.1. Overall, convalescent sera from patients with moderate disease had higher antibody levels and displayed a higher neutralizing ability against all strains than patients with mild or severe forms of the disease. The sera from BTI cases fell into one of two categories: half the sera had a high neutralizing activity against the ancestral B.1 strain as well as against the infecting strain, while the other half had no or a very low neutralizing activity against all strains. Although antibody levels against the spike protein and the RBD were lower in BTI sera than in unvaccinated convalescent sera, most neutralizing sera also retained partial neutralizing activity against Omicron BA.1, suggestive of a better cross-neutralization and higher affinity of vaccine-elicited antibodies over virus-induced antibodies. Accordingly, the IC50: antibody level ratios were comparable for BTI and convalescent sera, but remained lower in the neutralizing convalescent sera from patients with moderate disease than in BTI sera. The neutralizing activity of BTI sera was strongly correlated with antibodies against the Spike protein and the RBD. Together, these findings highlight qualitative differences in antibody responses elicited by infection in vaccinated and unvaccinated individuals. They further indicate that breakthrough infection with a pre-Omicron variant boosts immunity and induces cross-neutralizing antibodies against different strains, including Omicron BA.1.     

Chelating Polymers for Targeted Decontamination of Actinides: Application of PEI-MP to Hydroxyapatite-Th(IV)

In case of an incident in the nuclear industry or an act of war or terrorism, the dissemination of plutonium could contaminate the environment and, hence, humans. Human contamination mainly occurs via inhalation and/or wounding (and, less likely, ingestion). In such cases, plutonium, if soluble, reaches circulation, whereas the poorly soluble fraction (such as small colloids) is trapped in alveolar macrophages or remains at the site of wounding. Once in the blood, the plutonium is delivered to the liver and/or to the bone, particularly into its mineral part, mostly composed of hydroxyapatite. Countermeasures against plutonium exist and consist of intravenous injections or inhalation of diethylenetetraminepentaacetate salts. Their effectiveness is, however, mainly confined to the circulating soluble forms of plutonium. Furthermore, the short bioavailability of diethylenetetraminepentaacetate results in its rapid elimination. To overcome these limitations and to provide a complementary approach to this common therapy, we developed polymeric analogs to indirectly target the problematic retention sites. We present herein a first study regarding the decontamination abilities of polyethyleneimine methylcarboxylate (structural diethylenetetraminepentaacetate polymer analog) and polyethyleneimine methylphosphonate (phosphonate polymeric analog) directed against Th(IV), used here as a Pu(IV) surrogate, which was incorporated into hydroxyapatite used as a bone model. Our results suggest that polyethylenimine methylphosphonate could be a good candidate for powerful bone decontamination action.     

Ripening conditions: A tool for the control of Listeria monocytogenes in uncooked pressed type cheese

The effect of ripening conditions (two temperatures, 9 °C and 13 °C, and two relative humidities 93% and 97%) on the growth of Listeria monocytogenes and other microbial populations was evaluated in the cores and rinds of uncooked pressed type cheeses prepared with pasteurised milk and inoculated either with Streptococcus thermophilus only or with an anti-listerial consortium. Regardless of temperature and relative humidity (RH), inhibition by the anti-listerial consortium was stronger in the cheese cores than in the rinds. Temperature had no significant effect on L. monocytogenes counts in cores or rinds. However, at the beginning of ripening in the consortium cheese, L. monocytogenes growth was more strongly inhibited at 13 °C than at 9 °C. Regardless of inoculation type and ripening temperature, counts of L. monocytogenes were significantly lower in the cores and rinds of cheeses ripened at 93% than at 97% RH. Lactobacilli counts were higher at 13 °C than at 9 °C and at 93% than at 97% RH. Lactobacilli can help to inhibit L. monocytogenes by catabolising galactose and producing lactate. Further investigations will be needed to evaluate the effect of ripening at 13 °C and 93% RH on the sensorial properties of cheese.     

In-Situ Analyzing the Influence of Thermoelectromagnetic Convection on the Nucleation Ahead of the Advancing Interface During Directional Solidification

Sn-3wt%Pb alloy was directionally solidified without and with a 0.08T transverse magnetic field(TMF),and real-time recorded by in-situ synchrotron X-ray imaging.Results indicate that TMF shortened the distance from the location of nucleation to the advancing interface,and accelerated the growth rate of the equiaxed crystal,which caused the columnar-to-equiaxed transition(CET)finally.The thermoelectromagnetic convection(TEMC)in front of the interface and around the crystal’s dendritic branch should respond to changes of the distance and the growth rate.     

Cyclic invariance for discrete time-delay systems

This technical communique introduces a new concept of set invariance with respect to linear discrete time dynamics affected by delay. We are interested in the definition and characterization of sequences of cyclically invariant subsets in the state space. The algebraic conditions established in the late ’80s for linear dynamics are generalized to invariance analysis in the presence of delays for given sequences of polyhedral sets.     

Granulometry,cluster analysis and spatial distribution of manganese contaminated soils,Kgwakgwe, southeastern Botswana

The particle size distribution (PSD) of 400 Mn contaminated soil samples was established, and generated data were statistically analysed and spatially presented. The PSD for the 53 µm – 4 µm size fraction soil samples ranged from 11.05 to 100 wt %, whereas that for < 4 µm was from 0.3 to 30 wt %. Texturally, samples were dominantly silt loam, although silt and sandy loam were also present, as well as loam, loamy sand and clay classes. Six clusters were identified with cluster one being the most dominant occurring in sandy loam, silt loam and loamy sand. The < 53 µm fraction had three dominant areas, and the < 4 µm fraction had several unevenly presented populations as reflected in the maps. Because of its spatial distribution, the < 4 µm fraction may pose hazards to human health. Furthermore, predominance of Mn limits land use to subsistence agriculture with possibly low crop yield.     

Interpolymer complexes of poly(acrylamide) and poly(N-isopropylacrylamide) with poly(acrylic acid): a comparative study

The interpolymer complexation, through successive hydrogen bonding, between poly(acrylamide) (PAAm) and poly(N-isopropylacrylamide) (PNiPAAm) with poly(acrylic acid) (PAA) in aqueous solution has been viscometrically and potentiometrically investigated. The stoichiometry of the complexes formed was determined. By comparing the strength of the two complexes the very important contribution of the hydrophobic interaction in their formation has been indicated.     

Development of blown film linear low-density polyethylene–clay nanocomposites: Part A: Manufacturing process and morphology

In this study, linear low-density polyethylene (LLDPE)/clay nanocomposites with different clay contents were prepared by melt intercalation using two different compatibilizers: maleic anhydride grafted styrene–ethylene–butylene–styrene and maleic anhydride grafted polyethylene (PE-g-MA). Melt intercalation was achieved by twin extrusion and nanocomposite films were produced by blown film extrusion. Effects of clay and compatibilizer fractions and type of compatibilizer on the structure, permeability, and the barrier properties of the nanocomposite films were investigated. PE-g-MA was shown to notably improve the dispersion of clay layers in the polyethylene matrix, and this was examined by atomic force microscopy and X-ray diffraction. The latter tests have also highlighted the importance of the screw configuration: the presence of mixing elements favors the dispersion and distribution of nanoclay. Moreover, differential scanning calorimetry results have shown no significant effect of the clay on the crystallinity of the composite while thermogravimetric analysis tests have demonstrated a decrease of onset and peak of decomposition temperatures. Finally, barrier properties toward water vapor transmission were measured. It was proven that not also clay, but the compatibilizer participated in decreasing the permeability of the film. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48589.     

Microtribology,squeeze, and friction of the colloidal layer

Lubricant films containing colloidal overbased calcium salts have particular effects on detergency and on the wear process. The mechanical properties of such boundary films are very dependent on the process conditions, and are essentially a result of physico-chemical transformations of the colloid. Three types of films were compared: a film obtained by the drying of the base solvent, a film due to the compaction of the colloid between two steel surfaces, and a friction film obtained with this type of lubricant. Adsorption, compaction, and shear transformations induce a solid film. The pressure effect on the frictional behaviour of these colloidal films has been investigated using a surface force apparatus for low contact pressure (10⁴ to 10⁶ Pa), and using tribometers supporting heavy loads for the analysis of the high pressure domain. Above a critical pressure, evaluated at 10⁶ Pa, the colloidal film does not flow, but forms a compacted mattress sliding on the surface plane and squeezing a molecular layer of lubricant.