Adsorption ability of oxidized multiwalled carbon nanotubes towards aqueous Ce(III) and Sm(III)

The aim of the present work was to investigate the adsorption of Ce(III) and Sm(III) onto multiwalled carbon nanotubes (MWCNTs) oxidized with concentrate nitric acid. The effects of solution pH, adsorbent dosage, and contact time were studied by batch technique. Langmuir, Freundlich and D-R isotherms were used to describe the adsorption behavior of Ce(III) and Sm(III) by oxidized MWCNTs, and the experimental results fitted Freundlich model well. The maximum uptake capacities (q _m ) calculated by applying the Langmuir equation for samarium and cerium ions were found to be 89.28 and 92.59 (mg/g), respectively. A comparison of the kinetic models and the overall experimental data was best fitted by the pseudo second-order kinetic model. The calculated thermodynamic parameters (ΔG^o, ΔH^o, and ΔS^o) showed that the adsorption for Ce(III) and Sm(III) is feasible, spontaneous and exothermic at 30–60 °C. Moreover, more than 70% of Ce(III) and Sm(III) adsorbed onto Oxidized MWCNTs could be desorbed with HNO₃.     

Thermo-mechanical analysis in pulsed laser cladding of WC powder on Inconel 718

The increasing interest towards intelligent systems has led to a demand for the development of zero-defect strategies, with a paradigm shift from off-line and dedicated to in-line metrology with integrated robotic systems. However, a major barrier preventing the systematic uptake of in-line metrology is the lack of evaluation of system capability in terms of accuracy, repeatability and measurement time, when compared to the well-established coordinate measuring machine (CMM). In this study, a robotic Laser Radar (LR) solution is assessed in the context of automotive dimensional inspection of Body-In-White (BIW) applications. The objective is both to understand the effect of robot re-positioning error on measurement accuracy and repeatability and to compare measurement results against a CMM. Eighty-one surface points, six edge points, twenty-five holes and sixteen slots were selected from an industry standard measurement plan. Whilst LR exhibits a lower measurement accuracy than twin-column CMM, its repeatability is well within the specification limits for body shell quality inspection. Therefore, as a real-time in-line metrology tool, it is a genuine prospect to exploit. This research makes a significant contribution toward in-line metrology for dimensional inspection, for automotive application, for rapid detection and for correction of assembly defects in real time, with subsequent reduction of scrap and number of repairs/re-works.     

A comparison of omeprazole and placebo for bleeding peptic ulcer

BACKGROUND: The role of medical treatment for patients with bleeding peptic ulcers is uncertain. METHODS: We conducted a double-blind, placebo-controlled trial in 220 patients with duodenal, gastric, or stomal ulcers and signs of recent bleeding, as confirmed by endoscopy. In 26 patients the ulcers showed arterial spurting, in 34 there was active oozing, in 35 there were nonbleeding, visible vessels, and in 125 there were adherent clots. The patients were randomly assigned to receive omeprazole (40 mg given orally every 12 hours for five days) or placebo. The outcome measures studied were further bleeding, surgery, and death. RESULTS: Twelve of the 110 patients treated with omeprazole (10.9 percent) had continued bleeding or further bleeding, as compared with 40 of the 110 patients who received placebo (36.4 percent) (P<0.001). Eight patients in the omeprazole group and 26 in the placebo group required surgery to control their bleeding (P<0.001). Two patients in the omeprazole group and six in the placebo group died. Thirty-two patients in the omeprazole group (29.1 percent) and 78 in the placebo group (70.9 percent) received transfusions (P<0.001). A subgroup analysis showed that omeprazole was associated with significant reductions in recurrent bleeding and surgery in patients with nonbleeding, visible vessels or adherent clots, but not in those with arterial spurting or oozing. CONCLUSIONS: In patients with bleeding peptic ulcers and signs of recent bleeding, treatment with omeprazole decreases the rate of further bleeding and the need for surgery.     

Preparation of SAPO-34 catalyst and presentation of a kinetic model for methanol to olefin process (MTO)

Conversion of methanol to light olefins (MTO) using acidic SAPO-34 molecular-sieve as the reaction catalyst was studied in a differential fixed bed reactor within the temperature range of 375-425 °C and under 4 bar pressure. The importance of MTO process is due to the increasing demand for light olefins in recent years. SAPO-34 was synthesized by hydrothermal method, applying morpholine as the template. The latter compound was then changed into protonated form by ion exchange method with ammonium chloride at 80 °C. A simple stoichiometric scheme has been presented for MTO. In addition a mechanism for this process based on Langmuir-Hinshelwood formulation has been put forward and the kinetic parameters have been evaluated as functions of temperature.     

Power grid analysis and verification considering temperature variations

Process variations significantly impact leakage power, a pivotal parameter in designing a power grid. Because of the strong relationship between temperature and leakage power, the variations also impose statistical behavior on the operating temperature. In addition, the metal resistivity of a power grid increases with temperature. Therefore, ignoring the interdependency between leakage and temperature can introduce large errors in the power grid design. In this paper, a power grid analysis is proposed considering a statistical thermal profile across the grid. In addition, an efficient verification method is provided that ensures the robustness of the power grid in the presence of variations. A reliable estimation of the statistical thermal profile at the architecture level makes it possible to address any voltage violation early in the design process.     

Collision provoked failure sequencing in space reentry vehicles

This work underlines damage prognosis and crashworthiness verification studies aim to provide a fast methodology for investigation of complex and non-linear responses of future advanced reentry space vehicles. The output of the methodology can be broadcast over the internet almost instantaneously, depending on the area of damage and intricacy of the corresponding analysis, and accessed by mission control with no delay. To evaluate the methodology, the Space Shuttle Columbia damage scenario was considered. The response of the vehicle hybrid wing structures was assessed due to the high velocity dynamic loading caused by the impact of foams detached from the liquid hydrogen tank. In general, such high velocity to ballistic loading conditions can mostly be exerted by foreign object collisions during the vehicle atmospheric flight window, particularly, within the early launch phase. Coupled explicit finite element-micro mechanics constitutive impact damage evaluation models were constructed and compared to the test data provided by the Southwest Research Institute, San Antonio. The methodology developed provides the level of accuracy required with minimal dependency on rigorous calibration procedures otherwise deemed necessary by conventional modeling approaches.