Removal and recovery of lead(II) from single and multimetal (Cd, Cu, Ni, Zn) solutions by crop milling waste (black gram husk)

The study reports removal of heavy metals when present singly or in binary and ternary systems by the milling agrowaste of Cicer arientinum (chickpea var. black gram) as the biosorbent. The biosorbent removed heavy metal ions efficiently from aqueous solutions with the selectivity order of Pb>Cd>Zn>Cu>Ni. The biosorption of metal ions by black gram husk (BGH) increased as the initial metal concentration increased. Biosorption equilibrium was established within 30 min, which was well described by the Langmuir and Freundlich adsorption isotherms. The maximum amount of heavy metals (qmax) adsorbed at equilibrium was 49.97, 39.99, 33.81, 25.73 and 19.56 mg/g BGH biomass for Pb, Cd, Zn, Cu and Ni, respectively. The biosorption capacities were found to be pH dependent and the maximum adsorption occurred at the solution pH 5. Efficiency of the biosorbent to remove Pb from binary and ternary solutions with Cd, Cu, Ni and Zn was the same level as it was when present singly. The presence of Pb in the binary and ternary solutions also did not significantly affect the sorption of other metals. Breakthrough curves for continuous removal of Pb from single, binary and ternary metal solutions are reported for inlet-effluent equilibrium. Complete desorption of Pb and other metals in single and multimetal solutions was achieved with 0.1 M HCl in both shake flask and fixed bed column studies. This is the first report of removal of the highly toxic Pb, Cd, and other heavy metals in binary and ternary systems based on the biosorption by an agrowaste. The potential of application for the treatment of solutions containing these heavy metals in multimetal solutions is indicated.     

Linear State Space Feedforward and Feedback Structures for Blind Source Recovery in Dynamic Environments

Blind Source Recovery (BSR) denotes recovery of original sources or signals from environments, which may include convolution, temporal variation, and even non-linearity—without necessarily performing explicit environment identification. This paper presents two separate multiple-input multiple-output (MIMO) structures for dynamic linear Blind Source Recovery (BSR) of multiple stochastically independent source signals. We propose linear state space models for both the mixing environment and the demixing (or the recovering) adaptive network. The demixing network may assume either the feedforward or the feedback state space configuration. Separate algorithms have been derived for the adaptive estimation of the feedforward and the feedback demixing/recovering network’s parameters. These algorithms are based on the multivariable optimization theory and utilize the Riemannian contra-variant gradient (or the natural gradient) search under the constraints of a state space representation. Auxiliary conditions for the convergence of these algorithms have also been derived and discussed. Illustrative simulation examples have been included to demonstrate the successful adaptation results for both proposed demixing network structures in the case of an infinite impulse response (IIR)-type mixing environment for example source statistical distributions.     

Eu3+, Sm3+ Deep‐Red Phosphors as Novel Materials for White Light‐Emitting Diodes and Simultaneous Performance Enhancement of Organic–Inorganic Perovskite Solar Cells

The luminous efficiency of inorganic white light‐emitting diodes, to be used by the next generation as light initiators, is continuously progressing and is an emerging interest for researchers. However, low color‐rendering index (Ra), high correlated color temperature (CCT), and poor stability limit its wider application. Herein, it is reported that Sm³⁺‐ and Eu³⁺‐doped calcium scandate (CaSc₂O₄ (CSO)) are an emerging deep‐red‐emitting material with promising light absorption, enhanced emission properties, and excellent thermal stability that make it a promising candidate with potential applications in emission display, solid‐state white lighting, and the device performance of perovskite solar cells (PSCs). The average crystal structures of Sm³⁺‐doped CSO are studied by synchrotron X‐ray data that correspond to an extremely rigid host structure. Samarium ion is incorporated as a sensitizer that enhances the emission intensity up to 30%, with a high color purity of 88.9% with a 6% increment. The impacts of hosting the sensitizer are studied by quantifying the lifetime curves. The CaSc₂O₄:0.15Eu³⁺,0.03Sm³⁺ phosphor offers significant resistance to thermal quenching. The incorporation of lanthanide ion‐doped phosphors CSOE into PSCs is investigated along with their potential applications. The CSOE‐coated PSCs devices exhibit a high current density and a high power conversion efficiency (15.96%) when compared to the uncoated control devices.     

Relationship between carotid plaque surface morphology and perfusion: a 3D DCE-MRI study

Objective

This study aims to explore the relationship between plaque surface morphology and neovascularization using a high temporal and spatial resolution 4D contrast-enhanced MRI/MRA sequence.

Materials and methods

Twenty one patients with either recent symptoms or a carotid artery stenosis ≥40% were recruited in this study. Plaque surface morphology and luminal stenosis were determined from the arterial phase MRA images. Carotid neovascularization was evaluated by a previously validated pharmacokinetic (PK) modeling approach. K ^trans (transfer constant) and v _p (partial plasma volume) were calculated in both the adventitia and plaque.

Results

Image acquisition and analysis was successfully performed in 28 arteries. Mean luminal stenosis was 44% (range 11–82%). Both adventitial and plaque K ^trans in ulcerated/irregular plaques were significantly higher than smooth plaques (0.079 ± 0.018 vs. 0.064 ± 0.011 min^?1, p = 0.02; 0.065 ± 0.013 vs. 0.055 ± 0.010 min^?1, p = 0.03, respectively). Positive correlations between adventitial K ^trans and v _p against stenosis were observed (r = 0.44, p = 0.02; r = 0.55, p = 0.01, respectively).

Conclusion

This study demonstrates the feasibility of using a single sequence to acquire both high resolution 4D CE-MRA and DCE-MRI to evaluate both plaque surface morphology and function. The results demonstrate significant relationships between lumen surface morphology and neovascularization.

     

A Secure Routing Protocol with Trust and Energy Awareness for Wireless Sensor Network

Nodes in most of the deployments of Wireless Sensor Networks (WSNs) remain un-administered and exposed to variety of security attacks. Characterized by constrained resources and dynamically changing behavior of sensor nodes, reliable data delivery in WSNs is nontrivial. To counter node misbehavior attacks, traditional cryptographic and authentication based solutions have proved to be inappropriate due to high cost and incapability factors. Recently, trust based solutions have appeared to be viable solutions to address nodes’ misbehavior attacks. However, the existing trust based solutions incur high cost in trust estimation and network-wide dissemination which significantly increases traffic congestion and undermines network lifetime. This paper presents a Trust and Energy aware Secure Routing Protocol (TESRP) for WSN that exploits a distributed trust model for discovering and isolating misbehaving nodes. TESRP employs a multi-facet routing strategy that takes into consideration the trust level, residual energy, and hop-counts of neighboring nodes while making routing decisions. This strategy not only ensures data dissemination via trusted nodes but also balances out energy consumption among trusted nodes while traversing through shorter paths. Demonstrated by simulation results in NS-2, TESRP achieves improved performance in terms of energy consumption, throughput and network lifetime as compared to existing solutions.     

Post-Processing of Phased-Array Ultrasonic Inspection Data with Parallel Computing for Nondestructive Evaluation

Phased-array ultrasonic nondestructive evaluation is an effective tool of safety assurance for key structural components. The paper presents a general post-processing methodology for phased-array ultrasonic inspection data. The methodology is developed to integrate three components: mapping of sampling points to structure model, re-sampling from non-uniformly distributed sampling points in phased-array to a uniform volume, and data fusion strategies for multiple channels. An adaptive method called spatially adaptive Gaussian splatting is proposed for data re-sampling and fusion considering the reconstruction resolution and local characteristics of ultrasonic sound paths. This adaptivity provides a viable approach to minimize the effects of under-sampling, over-sampling, and holes which are introduced by the non-uniformly distributed sampling points. The processing of large scale data through segmentation and parallelization techniques is discussed in detail. The effectiveness and performance of the proposed methodology are investigated using actual phased-array ultrasonic testing data.     

Evaporation characteristics of kerosene droplets with dilute concentrations of ligand-protected aluminum nanoparticles at elevated temperatures

The evaporation characteristics of kerosene droplets containing dilute concentrations (0.1%, 0.5%, and 1.0% by weight) of ligand-protected aluminum (Al) nanoparticles (NPs) suspended on silicon carbide fiber were studied experimentally at different ambient temperatures (400–800 °C) under normal gravity. The evaporation behavior of pure and stabilized kerosene droplets was also examined for comparison. The results show that at relatively low temperatures (400–600 °C), the evaporation behavior of suspended kerosene droplets containing dilute concentrations of Al NPs was similar to that of pure kerosene droplets and exhibited two-stage evaporation following the classical d²-law. However, at relatively high temperatures (700–800 °C), bubble formation and micro-explosions were observed, which were not detected in pure or stabilized kerosene droplets. For all Al NP suspensions, regardless of the concentration, the evaporation rate remained higher than that of pure and stabilized kerosene droplets in the range 400–800 °C. At relatively low temperatures, the evaporation rate increased slightly. However, at relatively high temperatures (700–800 °C), the melting of Al NPs led to substantial enhancement of evaporation. The maximum increase in the evaporation rate (56.7%) was observed for the 0.5% Al NP suspension at 800 °C.     

Preparation of the chitosan containing nanofibers by electrospinning chitosan–gelatin complexes

Electrospinning is an interesting technique, which provides a facile and an effective mean in producing nonwoven fibrous materials; however, for producing nanofibers, investigation of the electrospinning conditions is very important. In this study, chitosan, gelatin, and their polyelectrolyte complexes (PECs) were electrospun to prepare nonwoven nanofibrous mats. The concentrations of chitosan and gelatin solutions and electric field (kV/cm) were optimized. The solutions were then blended in different ratios (0–100%) to get electrospun nanofibrous mats. Solution concentration and electric field showed pronounced effect on the electrospinnability and fiber diameter of these systems. Mostly large beads coexisted with the fibers were observed for chitosan at 1 wt% solution concentration, which then showed good electrospinnability at 2 wt% (nanofiber diameter was 145 and 122 nm at 15 and 20 kV/10 cm, respectively), whereas gelatin showed no electrospinnability below 15 wt% solution concentration and a homogenous fibers network at 15 wt% (149 nm at 20 kV/10 cm). The morphology and diameter of chitosan–gelatin PEC nanofibers varied with the chitosan/gelatin ratio. The crystallinity of chitosan was also observed to reduce with electrospinning and addition of gelatin. POLYM. ENG. SCI. 50:1887–1893, 2010. © 2010 Society of Plastics Engineers     

Preparation of grass-like GaN nanostructures: Its PL and excellent field emission properties

We here report highly pure and single crystalline grass-like gallium nitride (GaN) nanostructures obtained on silicon substrate via catalyst-assisted CVD route under NH₃ atmosphere inside horizontal tube furnace (HTF) by pre-treating the precursors with aqueous NH₃. The as-obtained GaN nanostructures were characterized by XRD, SEM, EDS, HRTEM and SAED. The field emission (FE) characteristics of grass-like GaN nanostructures exhibited a turn-on field of 7.82 V μm^− 1 and a threshold field of 8.96 V μm^− 1 which are quite reasonable for applications in electron emission devices, field emission displays and vacuum microelectronic devices. Room temperature photoluminescence (PL) measurements of grass-like GaN nanostructures exhibited a strong near-band-edge emission at 368.8 nm (3.36 eV) without any defects related emissions which shows its potential applications in optoelectronics.