Distribution of technetium in PUREX process streams

Extraction of technetium has been carried out from the aqueous medium containing nitric acid under different experimental conditions to investigate its extraction behaviour in 30% tri-n-butyl phosphate in n-dodecane. In order to study the distribution behaviour of technetium in different streams of PUREX process, experiments were carried out under process conditions. The distribution of technetium was also studied using anion-exchange resin. Based on these results, the path of technetium in the PUREX process streams has been established which will be useful in the development of an advanced PUREX flow-sheet for containment and isolation of technetium in an environmental friendly fuel cycle.     

Investigation of pad deformation and conditioning during the CMP of silicon dioxide films

An understanding of different aspects of chemical-mechanical polishing (CMP) is sought with emphasis on the polish pad degradation and conditioning during the polishing of silica films.In situ andex situ conditioning have been compared.In situ conditioning has proven to yield higher removal rates with improved, within wafer uniformities. Some of the factors contributing to the pad deterioration such as the conditioning tool down force, tool speed, and the type of solubilizing ions in the slurry is examined. The dependence on diamond particle sizes, nickel plated on to the conditioning discs, is discussed. The extent of pad wear caused by all of the above factors has been quantitatively determined and presented.     

A study of mechanisms of domain switching in a ferroelectric material via loading rate effect

A method to characterize the strain–electric field butterfly behavior based on the underlying domain switching mechanism is first presented. The effect of loading rate on the different characteristics of the strain–electric field butterfly behavior is then studied. By comparing the changes in these characteristics under different loading rates, it is established that the loading rate dependence of the strain–electric field butterfly behavior is mainly due to two factors: (i) the dependence of the switching of individual domains on the magnitude and duration of the loading time; and (ii) the variation of the transition electric field with the loading rate. Finally, the stability of switched domains is investigated by unloading and reloading the electric field at several predetermined values in the loading cycle. Several interesting attributes of the domain switching behavior that may shed further light on understanding the underlying mechanism of domain switching is illustrated in the present study. The present study also demonstrates that the proposed method of characterizing the strain–electric butterfly behavior based on the underlying domain switching mechanism is very effective for studying ferroelectric behavior under different loading conditions.     

Screening of Human Gut Bacterial Culture Collection Identifies Species That Biotransform Quercetin into Metabolites with Anticancer Properties

We previously demonstrated that flavonoid metabolites inhibit cancer cell proliferation through both CDK-dependent and -independent mechanisms. The existing evidence suggests that gut microbiota is capable of flavonoid biotransformation to generate bioactive metabolites including 2,4,6-trihydroxybenzoic acid (2,4,6-THBA), 3,4-dihydroxybenzoic acid (3,4-DHBA), 3,4,5-trihyroxybenzoic acid (3,4,5-THBA) and 3,4-dihydroxyphenylacetic acid (DOPAC). In this study, we screened 94 human gut bacterial species for their ability to biotransform flavonoid quercetin into different metabolites. We demonstrated that five of these species were able to degrade quercetin including Bacillus glycinifermentans, Flavonifractor plautii, Bacteroides eggerthii, Olsenella scatoligenes and Eubacterium eligens. Additional studies showed that B. glycinifermentans could generate 2,4,6-THBA and 3,4-DHBA from quercetin while F. plautii generates DOPAC. In addition to the differences in the metabolites produced, we also observed that the kinetics of quercetin degradation was different between B. glycinifermentans and F. plautii, suggesting that the pathways of degradation are likely different between these strains. Similar to the antiproliferative effects of 2,4,6-THBA and 3,4-DHBA demonstrated previously, DOPAC also inhibited colony formation ex vivo in the HCT-116 colon cancer cell line. Consistent with this, the bacterial culture supernatant of F. plautii also inhibited colony formation in this cell line. Thus, as F. plautii and B. glycinifermentans generate metabolites possessing antiproliferative activity, we suggest that these strains have the potential to be developed into probiotics to improve human gut health.     

SDN/NFV security framework for fog-to-things computing infrastructure

Currently, core networking architectures are facing disruptive developments, due to emergence of paradigms such as Software-Defined-Networking (SDN) for control, Network Function Virtualization (NFV) for services, and so on. These are the key enabling technologies for future applications in 5G and locality-based Internet of things (IoT)/wireless sensor network services. The proliferation of IoT devices at the Edge networks is driving the growth of all-connected world of Internet traffic. In the Cloud-to-Things continuum, processing of information and data at the Edge mandates development of security best practices to arise within a fog computing environment. Service providers are transforming their business using NFV-based services and SDN-enabled networks. The SDN paradigm offers an easily programmable model, global view, and control for modern networks, which demand faster response to security incidents and dynamically enforce countermeasures to intrusions and cyberattacks. This article proposes an autonomic multilayer security framework called Distributed Threat Analytics and Response System (DTARS) for a converged architecture of Fog/Edge computing and SDN infrastructures, for emerging applications in IoT and 5G networks. The major detection scheme is deployed within the data plane, consisting of a coarse-grained behavioral, anti-spoofing, flow monitoring and fine-grained traffic multi-feature entropy-based algorithms. We developed exemplary defense applications under DTARS framework, on a malware testbed imitating the real-life DDoS/botnets such as Mirai. The experiments and analysis show that DTARS is capable of detecting attacks in real-time with accuracy more than 95% under attack intensities up to 50 000 packets/s. The benign traffic forwarding rate remains unaffected with DTARS, while it drops down to 65% with traditional NIDS for advanced DDoS attacks. Further, DTARS achieves this performance without incurring additional latency due to data plane overhead.     

Sol–Gel Synthesis of PZT–Glass Nanocomposites Using a Simple System and Characterization

A simple inorganic system has been developed for the sol–gel synthesis of piezoelectric PZT–glass nanocomposites. Nanocrystalline PZT are nucleated from the amorphous xerogel through controlled heat treatment at 600°C. The formation of the crystalline phase, particle size, morphology, kinetics, and mechanism of crystallization of PZT in the glass matrix have been studied using X-ray diffraction, scanning electron microscopy, and differential thermal analysis. The piezoelectric characteristics of the PZT–glass compositions have been determined, and are correlated with the microstructure and the crystalline phase of PZT.     

Domain-Switching Criteria for Ferroelectric Materials Subjected to Electrical and Mechanical Loads

In this paper, existing domain-switching criteria are briefly reviewed and the predictions based on these domain-switching criteria are compared with the available experimental data for 180° and 90° domain switchings in lead lanthanum zirconate titanate (PLZT) and lead zirconate titanate (PZT), respectively. It is found that the predictions do not match the experimental results. Motivated by this observation, a new domain-switching criterion in terms of internal-energy density is proposed for combined mechanical and electrical loads. Based on consideration of the atomic structure of ferroelectric materials, it is recognized that 180° and 90° domain switchings result from different mechanisms and, thus, require different critical internal-energy densities for switching. The new criterion is found to yield very good predictions for both 180° and 90° domain switchings.     

The effect of work-hardening and pile-up on nanoindentation measurements

Nanoindentation is performed on the cross-section of copper samples subjected to surface mechanical attrition treatment (SMAT). The cross-section of the SMAT samples provides a unique microstructure with varying amounts of work-hardening depending on the distance from the SMAT surface. Results show that for a given indentation load the pile-up height decreases and the indentation depth increases as the distance from the SMAT surface increases, both following a power law relationship. Based on image analysis of the indented surface this increase in the pile-up height and decrease in indentation depth is attributed to the localization of plastic strain due to the increased resistance to dislocation motion in the work-hardened region. For a given amount of work-hardening (in terms of distance from SMAT surface), the indentation depth increased with the indentation load obeying a power law relationship with the exponent ranging from 0.58 to 0.68. However, the pile-up height increased linearly with the load, with the rate (slope) increasing with the amount of work-hardening. The observed linear increase in pile-up height with indentation load would naturally introduce an indentation size effect (ISE) if the hardness is corrected for the pile-up. Interestingly, this ISE associated with pile-up increased with an increase in indentation depth, in contradiction to the ISE associated with strain gradient. Deviation of the hardness values corrected for pile-up from the bulk behavior due to surface effect is highlighted and a method to obtain a bulk-equivalent hardness quantity representing the bulk behavior is proposed.