Synthesis of Fluorinated ZDDP Compounds

Volatile degradation products of zinc dialkyl dithio phosphate (ZDDP) composed of phosphorus and sulfur compounds reduce the efficiency of catalytic converters resulting in harmful emissions. A unique way of reducing ZDDP level while maintaining good antiwear performance has been achieved by reacting a novel additive FeF₃ with ZDDP. The objective of this research is to examine the chemical interactions between ZDDP and FeF₃ that yield the new chemical species responsible for the improved wear performance. The approach adopted involves studies of thermal degradation products of ZDDP that are formed in presence and absence of FeF₃. These intermediate products are responsible for the formation of protective tribofilms on the surface. Nuclear Magnetic Resonance Spectroscopy (³¹P and ¹⁹F) has been principally used to identify these products. Results have indicated the formation of new fluorinated phosphorus compounds formed as ‘early intermediate’ products in the reaction between ZDDP and FeF₃. The chemical differences observed were used to justify the improved tribological behavior of the new fluorinated ZDDP compounds in comparison to ZDDP. Paper was presented at the STLE/ASME International Joint Tribology Conference, October 23–25, 2006, San Antonio, TX. Paper Number IJTC2006-12053.     

Synthesis of cross-linked graft copolymer from [2-(methacryloyloxy)ethyl] trimethylammonium chloride and poly(vinyl alcohol) for removing chromium(VI) from aqueous solution

A novel graft copolymer of [2-(methacryloyloxy)ethyl] trimethylammonium chloride onto poly(vinyl alcohol) has been synthesized and it is cross-linked by glutaraldehyde for the investigation of its efficiency in removing Cr(VI) from aqueous solution. The chemical nature of the ion-exchange resin has been elucidated with the help of chemical test, Fourier transform infrared, thermo gravimetric analysis and DTA. Particle size, surface area, ion-exchange capacity, optimum pH, reaction time and temperature for Cr(VI) extraction were determined. Chromium(VI) adsorption kinetics, isotherm and thermodynamics have been studied. A plausible mechanism for chromium ion-exchange has been suggested.     

Impression creep of monolithic and composite lead free solders

Even though several EMS (Electronic manufacturing services) companies are currently producing “lead free” products, a general notion of apprehension still exists in the industry, primarily due to the lack of sufficient mechanical reliability data supporting the use of lead free alloys. The current study was an effort to generate an understanding of the mechanisms of creep deformation in monolithic and composite (Ag and Cu reinforced) Sn–3.5Ag and Sn–3.0Ag–0.5Cu lead free alloys in the high stress high temperature regime. Small volume solder samples were reflowed using a custom built computer controlled resistance furnace. Impression creep testing was employed to determine the activation energy and stress exponent. A careful analysis of the collected data revealed the underlying creep mechanisms and the following conclusions could be made. Both Sn–3.5Ag and Sn–3.0Ag–0.5Cu exhibited higher creep resistance as compared to the eutectic tin–lead solder under all tested conditions, with the ternary lead free alloy marginally outperforming the binary lead free alloy. Composite solders performed better as compared to monolithic solders. Furthermore, Cu reinforced solders demonstrated higher creep resistance as compared to Ag reinforced solders.     

XANES analysis of calcium and sodium phosphates and silicates and hydroxyapatite–Bioglass®45S5 co-sintered bioceramics

Bioglass®45S5 was co-sintered with hydroxyapatite at 1200 °C. When small amounts (< 5 wt.%) of Bioglass®45S5 was added it behaved as a sintering aid and also enhanced the decomposition of hydroxyapatite to β-tricalcium phosphate. However when 10 wt.% and 25 wt.% Bioglass®45S5 was used it resulted in the formation of Ca₅(PO₄)₂SiO₄ and Na₃Ca₆(PO₄)₅ in an amorphous silicate matrix respectively. These chemistries show improved bioactivity compared to hydroxyapatite and are the subject of this study. The structure of several crystalline calcium and sodium phosphates and silicates as well as the co-sintered hydroxyapatite–Bioglass®45S5 bioceramics were examined using XANES spectroscopy. The nature of the crystalline and amorphous phases were studied using silicon (Si) and phosphorus (P) K- and L_2,3-edge and calcium (Ca) K-edge XANES.Si L_2,3-edge spectra of sintered bioceramic compositions indicates that the primary silicates present in these compositions are sodium silicates in the amorphous state. From Si K-edge spectra, it is shown that the silicates are in a similar structural environment in all the sintered bioceramic compositions with 4-fold coordination.Using P L_2,3-edge it is clearly shown that there is no evidence of sodium phosphate present in the sintered bioceramic compositions. In the P K-edge spectra, the post-edge shoulder peak at around 2155 eV indicates that this shoulder to be more defined for calcium phosphate compounds with decreasing solubility and increasing thermodynamic stability. This shoulder peak is more noticeable in hydroxyapatite and β-TCP indicating greater stability of the phosphate phase. The only spectra that does not show a noticeable peak is the composition with Na₃Ca₆(PO₄)₅ in a silicate matrix indicating that it is more soluble compared to the other compositions.     

Profiling hot isostatically pressed canister–wasteform interaction for Pu-bearing zirconolite-rich wasteforms

Zirconolite-rich full ceramic wasteforms designed to immobilize Pu-bearing wastes were produced via hot isostatic pressing (HIP) using stainless steel (SS) and nickel (Ni) HIP canisters. A detailed profiling of the elemental compositions of the major and minor phases over the canister–wasteform interaction zone was performed using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS) characterization. Bulk sample analyses from regions near the center of the HIP canister were also conducted for both samples using X-ray diffraction and SEM-EDS. The sample with the Ni HIP canister showed almost no interaction zone with only minor diffusion of Ni from the inner wall of the canister into the near-surface region of the wasteform. The sample with the SS HIP canister showed ∼100–120 μm of interaction zone dominated by high-temperature Cr diffusion from canister materials to the wasteform with the Cr predominantly incorporated into the durable zirconolite phase. We also examined, for the first time, changes to the HIP canister wall thickness caused by HIPing and demonstrated that no canister wall thinning occurred. Instead, in the areas examined, the canister wall thickness was observed to increase (up to ∼20%) due to the compression occurring during the HIP cycle. Further, only sparse formation of (Cr, Mn)-rich oxide particles were noted within the HIP canister inner wall area immediately adjacent to the ceramic material, with no evidence for reverse diffusion of ceramic materials. Though the HIP canister–wasteform interaction extends to ∼120 μm when using an SS HIP canister for the system investigated, this translates to <<1 vol.% for an industrial scale HIPed wasteform. Importantly, the HIP canister–wasteform interactions did not produce any obviously less durable phases in the wasteform or had any detrimental impact on the HIP canister properties.     

Synroc technology: Perspectives and current status (Review)

Dr Eric (Lou) Vance spent 32 years at the Australian Nuclear Science and Technology Organisation (ANSTO), where he was dedicated to the development of Synroc technology, a waste treatment solution for intractable nuclear wastes. The original form of Synroc, a multiphase ceramic wasteform based on stable and leach resistant titanate minerals, was invented by Australian scientists in the late 1970s. This formulation was directed toward the immobilization of PUREX wastes from the reprocessing of nuclear fuels. Synroc at ANSTO under the scientific leadership of Dr Vance since evolved beyond these original titanate ceramics into a waste treatment technology platform. This platform can be applied to produce glass, glass-ceramic and ceramic wasteforms and offers distinct advantages in terms of waste loading and suppressing volatile losses. The platform therefore provides an opportunity to treat those waste streams that are problematic for glass matrices alone or existing vitrification process technologies. Such wastes include, for example, actinide-bearing wastes, those that contain large proportions of refractory elements, those with significant fission product or corrosive volatile emissions and those wastes resulting from radiopharmaceutical production. The implementation of the latter will see the industrialization of Synroc technology via a first-of-a-kind Synroc Waste Treatment Facility that is currently under construction at ANSTO. This paper will review Synroc technology, particularly noting the substantial and essential contributions from the late Dr Vance. The review will also provide some perspective on the development of the technology for nuclear waste immobilization and describe the significant recent advancements at ANSTO.     

Error probability of 2DPSK with phase noise

A simple tight upper bound on the BEP of 2DPSK over the AWGN channel with phase noise in the received signal is obtained. The phase is modeled as a Gaussian random process which is slowly varying compared to the bit rate so that a piecewise-constant approximation can be made. The bound is verified by computer simulations, and it provides good estimates of the error probability. It shows that for high SNR the error probability decreases as the reciprocal of the square-root of the SNR. The results are applicable in particular to heterodyne optical communications     

Design and Implementation of Routing Algorithm to Enhance Network Lifetime in WBAN

Today’s era is the era of smart and remote applications exploiting advancement in sensors, cloud, Internet of things etc. Major application is in healthcare monitoring and support using wireless body area network (WBAN) in which sensor nodes sense vital physiological parameters and send to server through sink i.e. smart phone nowadays for seamless monitoring. The most significant issue in such applications is energy efficiency which leads to enhanced network life time that ensures uninterrupted seamless services. From source to sink data transmission may occur considering three different scenarios: source to sink single hop direct data transmission irrespective of in-between node distance, source to sink multi hop data transmission in which transmission range of source node is fixed at a threshold to find next forwarder node and transmission range of source node is incremented by affixed value until data gets transmitted to sink. In this work WBAN having different network configurations based on fixed or random positions of nodes have been simulated. Different scenarios with fixed and varying number of nodes are framed and simulated using MATLAB 2020a for performance evaluation of proposed algorithm in terms of energy consumption, network lifetime, path loss etc. due to data transmission from source to sink. Experimental results show that incremental approach is better than direct one in terms of energy consumption, path loss and network lifetime. While selecting transmission range of a source node, it is considered to keep Specific Absorption Rate (SAR) lower to reduce impact on human tissue.

     

Design and development of new reconfigurable architectures for LSB/multi-bit image steganography system

The most crucial task in real-time processing of steganography algorithms is to reduce the computational delay and increase the throughput of a system. This critical issue is effectively addressed by implementing steganography methods in reconfigurable hardware. In the proposed framework, a new high-speed reconfigurable architectures have been designed for Least Significant Bit (LSB) or multi-bit based image steganography algorithm that suits Field Programmable Gate Arrays (FPGAs) or Application Specific Integrated Circuits (ASICs) implementation. The architectures are designed and instantiated to implement the complete steganography system. The proposed system is competent enough to provide larger throughput, since high degrees of pipelining and parallel operations are incorporated at the module level. The evolved architectures are realized in Xilinx Virtex-II Pro XC2V500FG256-6 FPGA device using Register Transfer Level (RTL) compliant Verilog coding and has the capacity to work in real-time at the rate of 183.48 frames/second. Prior to the FPGA/ASIC implementation, the proposed steganography system is simulated in software to validate the concepts intended to implement. The hardware implemented algorithm is tested by varying embedding bit size as well as the resolution of a cover image. As it is clear from the results presented that the projected framework is superior in speed, area and power consumption compared to other researcher’s method.     

Hysteresis behavior of t-stub connections with superelastic shape memory fasteners

This study compares the energy dissipative characteristics of bolted t-stub connections using steel and shape memory alloy (SMA) fasteners. The initial phase of the study focused on the optimization of the SMA superelastic effect using two different heat treatment temperatures. The samples were then subjected to tensile testing to determine transformation stress, tensile strength, and fracture strain. In addition, low cycle fatigue tests were conducted to examine the energy dissipative characteristics of these superelastic SMAs heat treated at the two temperatures. The cycled samples were then tensile tested to determine the effect of fatigue cycling on transformation stress, tensile strength, and fracture strain. Results from the mechanical tests were analyzed to determine the preferred heat treatment temperature that resulted in the least residual strain and the largest energy dissipative characteristics. The second phase of the study involved t-stub connection testing using steel and SMA double-ended threaded rod fasteners. The optimum heat treatment determined in the first phase was used to develop the SMA fasteners for the t-stub connection tests. Experimental hysteresis results from the t-stub connection tests were used to compare the energy dissipation capacity of the connections with SMA and steel fasteners.