ζ-potential characterization of collagen and bovine serum albumin modified silica nanoparticles: a comparative study

In this study, bovine serum albumin (BSA) and collagen (COLL) were adsorbed independent of one another, onto the surface of silica nanoparticles (SNPs) at pH’s where the ζ-potential of the proteins were equal in magnitude, but opposite to the SNP surface to ascertain the differences in surface coverage and conformation in the adsorbed layer. In both systems, increasing the concentration of free protein resulted in an increase in protein surface coverage and ζ values, with ζ values approaching that of native protein at high surface coverage. However, a lower critical charge reversal concentration range was measured for COLL relative to BSA (COLL: 0–25 μg/mL, BSA: 25–90 μg/mL). Additionally, a considerable difference in ζ for adsorbed protein versus free protein was observed. These results when interpreted in terms of the theory of Ottewill and Watanabe indicate a higher Gibbs energy of association for COLL versus BSA on SNP surfaces, accompanied by perturbation in protein structure.     

Performance analysis of burst-mode receivers with clock phase alignment and forward error correction for GPON

We experimentally demonstrate the performance analysis of burst-mode receivers (BMRx) in a 622 Mb/s 20-km gigabit-capable passive optical network (GPON) uplink. Our receiver features automatic phase acquisition using a clock phase aligner (CPA), and forward-error correction using (255, 239) Reed-Solomon (RS) codes. The BMRx provides instantaneous (0 preamble bit) phase acquisition and a packet-loss ratio (PLR) < 10^?6 for any phase step (±2π rads) between consecutive packets, while also supporting more than 600 consecutive identical digits (CIDs). The receiver also accomplishes a 3-dB coding gain at a bit-error rate (BER) of 10^?10. The CPA makes use of a phase picking algorithm and an oversampling clock-and-data recovery circuit operated at 2× the bit rate. The receiver meets the GPON physical media dependent layer specifications defined in the ITU-T recommendation G.984.2 standard. We investigate the PLR performance of the system and quantify it as a function of the phase step between consecutive packets, received signal power, CID immunity, and BER, while also assessing the tradeoffs in preamble length, power penalty, and pattern correlator error resistance. We also study the impact of mode-partition noise in the GPON uplink in terms of the effective PLR and BER coding gain performance of the system. In addition, we demonstrate how the CPA and the RS(255, 239) codes can be used in tandem for dynamic burst-error correction giving reliable BERs in bursty channels.     

In situ single-grain peak profile measurements on Ti–7Al during tensile deformation

High-energy three-dimensional X-ray diffraction with medium and high reciprocal space resolution was applied to study in situ tensile deformation of Ti–7Al specimens. Samples with planar and random dislocation microstructures were prepared and characterized by electron microscopy. Stress tensors of individual grains were obtained at several loads up to 2% deformation. The stress tensors were found to rotate, and resolved shear stresses were calculated. High-resolution reciprocal space maps of selected grains were recorded. Azimuthal and radial distributions were visualized and discussed in terms of idealized dislocation structures. Heterogeneous grain rotations were observed for the planar microstructure and found to be consistent with activation of the highest stressed basal slip system. Intra-granular strain gradients were detected in excess of the intrinsic radial dislocation peak broadening. The potential of combining the applied techniques with modeling to obtain multiple length-scale information during deformation of bulk specimens is discussed.     

Reduced graphene oxide wrapped sulfur nanocomposite as cathode material for lithium sulfur battery

Sulfur has been investigated as an active electrode material for secondary batteries due to theoretically specific capacity compared to the lithium-ion battery. In the present study, reduced graphene oxide (RGO) sheets wrapped Sulfur nanocomposite (S-RGO) synthesized by hydrothermal method and confirmed the wrapping of RGO sheets on Sulfur nanoparticles by various analytical techniques. The synthesized S-RGO nanocomposite demonstrated improved interaction of sulfur nanoparticles with RGO which is confirmed through XPS analysis. The synthesized S-RGO resulted in significantly improved reversible specific capacity and higher rate capability (823 mAh/g at 0.1C, 400 mAh/g at 1C) with 77 wt% of sulfur loading amount on the cathode of the Li–S battery. Therefore, the present study opens up new insights into sustainable development in the field of Li–S battery energy storage applications.     

The application of connectionism to query planning/scheduling in intelligent user interfaces

In the mid-1990s, the Earth Observing System (EOS) will generate an estimated 10 Terabytes of data per day. Making full use of this enormous amount of data will require sophisticated technologies from real-time distributed Artificial Intelligence (AI) and data management. Without regard to the overall problems in distributed AI, this paper focuses on developing efficient models for doing query planning/scheduling in intelligent user interfaces that reside in a network environment. Before intelligent query/planning can be done, a model for real-time AI planning/scheduling must be developed. As connectionist models (CM) have shown promise in decreasing run-times, this paper proposes a connectionist approach to AI planning/scheduling. The solution involves merging a CM rule-based system to a general spreading activation model for the generation and selection of plans. A system has been implemented in the Rochester Connectionist Simulator and runs on a Sun 3/260.