PVC membrane potentiometric sensor based on 5-pyridino-2,8-dithia[9](2,9)-1,10-phenanthroline-phane for selective determination of neodymium(III)

Spectrofluorometric studies on the binding properties of 5-pyridino-2,8-dithia[9](2,9)-1,10-phenanthrolinephane (L) toward La3+, Sm3+, Gd3+, Yb3+, and Nd3+ in methanol solution revealed the occurrence of both 1:1 and 2:1 (ligand/metal) complexation with a stability order of Nd3+ > Yb3+ > Gd3+ > Sm3+ > La3+. Consequently, L was used as a suitable neutral ionophore for the preparation of a novel polymeric membrane-selective electrode for Nd3+ ion. The electrode exhibited a Nernstian response over a wide concentration range (1.0 x 10(-6)-1.0 x 10(-2) M) with a low limit of detection of 7.9 x 10(-7) M. The electrode possesses a fast response time of <5 s and can be used for at least 9 weeks without observing any considerable deviation. The proposed electrode revealed a very good selectivity for Nd3+ over a wide variety of alkali, alkaline earth, transition, and heavy metal ions, including members of the lanthanide family other than Nd3+. The potentiometric response of the electrode is independent of the pH of test solution in the pH range 4.0-6.5. The proposed electrode was successfully applied to the recovery of Nd3+ ion from tap water samples and, also, as an indicator electrode, in potentiometric titration of neodymium(III) ions.     

Near-Term Travel Speed Prediction Utilizing Hilbert–Huang Transform

Abstract:  Accurate short-term prediction of travel speed as a proxy for time is central to many Intelligent Transportation Systems, especially for Advanced Traveler Information Systems and Advanced Traffic Management Systems. In this study, we propose an innovative methodology for such prediction. Because of the inherently direct derivation of travel time from speed data, the study was limited to the use of speed only as a single predictor. The proposed method is a hybrid one that combines the use of the empirical mode decomposition (EMD) and a multilayer feedforward neural network with backpropagation. The EMD is the key part of the Hilbert–Huang transform, which is a newly developed method at NASA for the analysis of nonstationary, nonlinear time series. The rationale for using the EMD is that because of the highly nonlinear and nonstationary nature of link speed series, by decomposing the time series into its basic components, more accurate forecasts would be obtained. We demonstrated the effectiveness of the proposed method by applying it to real-life loop detector data obtained from I-66 in Fairfax, Virginia. The prediction performance of the proposed method was found to be superior to previous forecasting techniques. Rigorous testing of the distribution of prediction errors revealed that the model produced unbiased predictions of speeds. The superiority of the proposed model was also verified during peak periods, midday, and night. In general, the method was accurate, computationally efficient, easy to implement in a field environment, and applicable to forecasting other traffic parameters.     

Kinetic modeling and thermodynamic study to remove Pb(II), Cd(II), Ni(II) and Zn(II) from aqueous solution using dead and living Azolla filiculoides

Dead Azolla filiculoides can remove Pb(2+),Cd(2+), Ni(2+) and Zn(2+) corresponding to second-order kinetic model. The maximum adsorption capacity (Q(max)) to remove these metal ions by the alkali and CaCl(2)/MgCl(2)/NaCl (2:1:1, molar ratio) activated Azolla from 283 to 313K was 1.431-1.272, 1.173-0.990, 1.365-1.198 and 1.291-0.981mmol/g dry biomass, respectively. Q(max) to remove these heavy metals by the non-activated Azolla at the mentioned temperature range was obtained 1.131-0.977, 1.092-0.921, 1.212-0.931 and 1.103-0.923mmol/g dry biomass, respectively. In order to remove these metal ions by the activated Azolla, the enthalpy change (DeltaH) was -4.403, -4.495, -4.557 and -4.365kcal/mol and the entropy change (DeltaS) was 2.290, 1.268, 1.745 and 1.006cal/molK, respectively. While, to remove these metal ions by the non-activated Azolla, DeltaH was -3.685, -3.766, -3.967 and -3.731kcal/mol and DeltaS was 2.440, 1.265, 1.036 and 0.933cal/molK, respectively. On the other hand, the living Azolla removed these heavy metals corresponding to first-order kinetic model. It was also shown that pH, temperature and photoperiod were effective both on the rate of Azolla growth and the rate of heavy metals uptake during 10 days. It was appeared the use of Ca(NO(3))(2) increased both Azolla growth rate and the rate of heavy metals uptake while the using KNO(3) although increased Azolla growth rate but decreased the rate of heavy metals uptake.     

Image-based gating of intravascular ultrasound pullback sequences

Intravascularultrasound (IVUS) sequences recorded in vivo are subject to a wide array of motion artifacts as the majority of these studies are performed within the coronary arteries of a beating heart. To eliminate these artifacts, an electrocardiogram (ECG) signal is typically used to gate (collect) those frames recorded at the points in time associated with a particular fraction of the cardiac cycle. However, this technique may be suboptimal for a number of reasons, among which is the difficulty of determining the optimal fraction at which to gate. This value is generally nonobvious. To circumvent this problem, we introduce a frame-gating method for IVUS pullbacks that mimics ECG (i.e., in the sense that it selects only one frame per cardiac cycle), but will automatically choose the fraction of the cycle that renders the most stable gated frame set. Stability here is gauged by measuring interframe similarity. Our method operates exclusively on the imagery data and does not require ECG or any form of image segmentation or other high-level image analysis. To validate our algorithm, we compare its behavior versus true ECG gating.     

Polyurethane-SAPO-34 mixed matrix membrane for CO2/CH4 and CO2/N2 separation

SAPO-34 nanocrystals (inorganic filler) were incorporated in polyurethane membranes and the permeation properties of CO₂, CH_4, and N₂ gases were explored. In this regard, the synthesized PU-SAPO-34 mixed matrix membranes (MMMs) were characterized via SEM, AFM, TGA, XRD and FTIR analyses. Gas permeation properties of PU-SAPO-34 MMMs with SAPO-34 contents of 5 wt%, 10 wt% and 20 wt% were investigated. The permeation results revealed that the presence of 20 wt% SAPO-34 resulted in 4.45%, 18.24% and 40.2% reductions in permeability of CO_2, CH_4, and N₂, respectively, as compared to the permeability of neat polyurethane membrane. Also, the findings showed that at the pressure of 1.2 MPa, the incorporation of 20 wt% SAPO-34 into the polyurethane membranes enhanced the selectivity of CO₂/CH₄ and CO₂/N₂, 14.43 and 37.46%, respectively. In this research, PU containing 20 wt% SAPO-34 showed the best separation performance. For the first time, polynomial regression (PR) as a simple yet accurate tool yielded a mathematical equation for the prediction of permeabilities with high accuracy (R² > 99%).     

Facile Synthesis of 7-Aryl-benzo[h]tetrazolo[5,1-b]quinazoline-5,6-dione Fused Polycyclic Compounds by Using a Novel Magnetic Polyurethane Catalyst

Novel Brönsted acid functionalized magnetic polymeric nanocomposite, Ba_0.5Sr_0.5Fe₁₂O₁₉@PU-SO₃H, has been successfully synthesized and characterized by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) techniques. The catalytic activity of the nanocomposite was tested in the regioselective synthesis of 7-aryl-benzo[h]tetrazolo [5,1-b] quinazoline-5,6-diones in an eco-friendly and recyclable media, deep eutectic solvent (DES), based on choline chloride and urea. This novel method offers several advantages, such as high yields, short reaction time, environmentally friendly reaction media, easy isolation of the product, and also offers an easy method for the synthesis of nanocatalysts. The catalyst was readily recycled by the use of an external magnetic field and could be reused 6 times without significant loss of activity or mass. DES as one of the most promising environmentally benign and cost-effective alternatives to conventional ionic liquids and volatile organic solvents was recovered from the aqueous filtrate by evaporating the water under vacuum. The recycled DES was used up to 4 runs without any loss in activity.     

Stress fissuring and process duration during rough rice convective drying affected by continuous and stepwise changes in air temperature

During rough rice drying, gradients of moisture content and glass transition temperature cause thermal and mechanical stresses inside the kernel. These stresses eventuate to kernel fissuring during the milling process. In this study, convective drying of Hashemi (long grain) rough rice was applied to investigate the effect of continuous and stepwise changes in air temperature on stress cracking index and process duration. Toward this objective, the concepts of glass transition and analysis of moisture contents distributions within the rice kernel were determined through a numerical modeling of mass transfer. For stepwise temperature change, the drying experiments were conducted at temperatures above the glass transition temperature. Results indicated that the stress cracking index under stepwise temperature change conditions (i.e., within the rubbery state) was reduced compared to the continuous mode probably due to a drip in the moisture content gradients created inside the kernels during the drying process. Moreover, the drying duration significantly was shortened when the kernel was dried within the rubbery state due to faster diffusion moisture within the kernel.     

Treatability of U.S. Environmental Protection Agency contaminant candidate list viruses: removal of coxsackievirus and echovirus using enhanced coagulation

Enhanced coagulation was evaluated for removal efficacy of coxsackievirus and echovirus (Contaminant Candidate List [CCL] enteroviruses), poliovirus, four potential surrogate bacteriophages, and dissolved organic carbon (DOC). Viruses and DOC were effectively removed using enhanced coagulation, with removals generally improving as dose increased and pH decreased. Optimal enhanced coagulation conditions of 40 mg/L FeCl3 and pH between 5 and 6.5 resulted in a maximum removal of 3.0 logs of coxsackievirus B6, 1.75 logs of echovirus 12, 2.5 logs of poliovirus 1, 1.8 logs of fr, 1.3 logs of phi-X174, 0.36 logs of MS2, 0.29 logs of PRD1, and 41% DOC. Bacteriophages fr and phi-X174 appear to be the most representative surrogates for the physical removal of coxsackievirus, while MS2 and PRD1 are more conservative. For echovirus, MS2 and PRD1 appearto bethe most appropriate surrogates. The relative removal profiles of the enteroviruses (greatest removal of coxsackievirus followed by poliovirus and then echovirus) suggest that studies of the physical removal of poliovirus may be extended to the CCL enteroviruses. These results contribute to evaluations of the CCL and regulatory status of coxsackievirus and echovirus and aid in building a database of the treatment efficiencies of enteroviruses and their surrogates.     

The Role of Welding Parameters on Achieving a Combination of High Strength and Ductility in Gas Tungsten Arc Welding of Cu–7Al–3Fe Aluminum Bronze

The weldability of aluminum bronze alloys lends it to fabrication of items such as pipes and pressure vessels. Thus, obtaining high strength along with good ductility is necessary. Gas tungsten arc welding of Cu–7Al–3Fe aluminum bronze alloy was performed by variation of some parameters such as shielding gas flow rate, preheat and post weld heat treatment. Optical and scanning electron microscopy along with EDX analysis was applied for different samples. Microhardness measurements and tensile tests were performed to see the effect of these parameters on ultimate tensile strength and ductility of samples.