Estimating weak ratiometric signals in imaging data. II. Meta-analysis with multiple, dual-channel datasets

Ratiometric fluorescent indicators are used for making quantitative measurements of a variety of physiological variables. Their utility is often limited by noise. This is the second in a series of papers describing statistical methods for denoising ratiometric data with the aim of obtaining improved quantitative estimates of variables of interest. Here, we outline a statistical optimization method that is designed for the analysis of ratiometric imaging data in which multiple measurements have been taken of systems responding to the same stimulation protocol. This method takes advantage of correlated information across multiple datasets for objectively detecting and estimating ratiometric signals. We demonstrate our method by showing results of its application on multiple, ratiometric calcium imaging experiments.     

Structure–property relationship of electron‐beam‐modified EPDM rubber

Electron‐beam‐initiated grafting of trimethylolpropane triacrylate (TMPTA) onto the bulk ethylene propylene diene monomer (EPDM) was carried out with varying concentrations of TMPTA at a constant irradiation dose of 100 kGy and over a wide range of irradiation doses (0–500 kGy) at a fixed concentration (10%) of TMPTA. The rubber was also modified in the bulk by tripropylene glycol diacrylate (TPGDA, 10%) and tetramethylol methane tetraacrylate (TMMT, 10%) at an irradiation dose of 100 kGy. The modified rubbers were characterized by IR spectroscopy, crosslinking density measurements, and mechanical, dynamic mechanical, and electrical properties. The IR studies indicated increased peak absorbances at 1730, 1260, and 1019 cm⁻¹ due to increased 〉CO and C O C concentrations up to certain levels of TMPTA and irradiation dose. These are accompanied by an increase in the crosslinking density. The tensile strength of the samples increases gradually with increasing both the concentration of the monomer and radiation dose up to a certain level. The values of the modulus also increase at the expense of the elongation at break. An increase in the number of double bonds from two in the case of the diacrylate to four in the case of the tetraacrylate also brings about an increase in the tensile strength and moduli values. The elongation at break, however, decreases. The DMTA measurements indicate changes in the glass transition temperature, T_g, and tan δ_max on modification. The T_g shifts to a higher temperature with a simultaneous lowering of the tan δ_max values as the TMPTA level is increased. A similar trend is observed when the irradiation dose is increased and the nature of the monomer changes from di‐ to tetraacrylate. The dielectric loss tangent registers an increase on modification by irradiation of TMPTA while the permittivity is decreased. All the results could be explained on the basis of the structural modification and crosslinking density. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 323–337, 2000     

Performance optimisation of laminar fully developed flow through square ducts with rounded corners

A study on combined first and second law based optimisation of thermal-hydraulic performance of laminar fully developed flow through square ducts with rounded corners has been presented in this paper. The objective functions have been considered according to suggestions of Webb and Bergles [7]. Four specific geometric constraints have been imposed on the shape of the ducts and these ducts have also been subjected to three different thermal and (or) hydraulic constraints. Two different thermal boundary conditions have been considered and the correlations for friction factor and Nusselt numbers have been adopted from the study of Ray and Misra [21]. The results obtained from the present study clearly show that the optimal duct geometry strongly depends on geometric and thermal-hydraulic constraints, as well as, the objective functions and hence, no general comment can be made with respect to the superiority of a particular geometry of the ducts. Nevertheless, the present study also shows that although entropy generation minimisation may be considered to be an important tool, one requires being careful in using it for thermal-hydraulic optimisation since it may lead to contradictory results for some of the performance evaluation criteria.     

Effect of Cryogenic Pre-Treatment on Breakage Characteristics of Rocks

Improvement of energy efficiency in comminution of rocks using various pretreatment methods is being explored worldwide. This paper presents experimental data on breakage characteristics of granite and sandstone using cryogenic pre-treatment. The samples were treated with varying duration of immersion in liquid nitrogen. Combined pretreatment using oven heating followed by quenching in liquid nitrogen were also explored. The results indicate that using cryogenic pretreatment uniaxial tensile strength of granite can be decreased by more than 40% while in uniaxial compressive strength about 28% reduction is possible. For sandstone as much as 33% reduction in uniaxial compressive strength was observed.

     

Factorial Design Approach to Investigate the Effects of Groundwater Cooccurring Solutes on Arsenic Removal by Electrocoagulation

Effects of groundwater cooccurring solutes such as phosphate (PO4), silicate (SiO3), bicarbonate (HCO3), calcium (Ca), and iron (Fe) on arsenic removal were investigated in this study. Investigation by two-level full-factorial designed experiments revealed that PO4 and SiO3 have negative effect on arsenic removal, whereas HCO3 has negligible positive effect. The effects of Ca and Fe present in groundwater have positive effect on arsenic removal by electrocoagulation (EC). Hypothesis testing at 5% significance level suggests that alkalinity (HCO3) is not an important parameter in arsenic removal by EC in naturally occurring pH range of water.     

Prediction of Arsenic Removal by Electrocoagulation: Model Development by Factorial Design

Model was developed by two-level five-factor full-factorial designed-experiment to predict arsenic removal from contaminated water by electrocoagulation. Five factors, namely arsenic concentration (As), solution volume (V); current (I), electrode area (A), and current processing time (t) were investigated. Among the factors, arsenic concentration (As) and volume (V) have negative effect, and area (A), time (t), and current (I) have positive effect on arsenic removal. Within the studied levels of the factors, variance analysis at 5% significance level indicated that electrode area is not significant in arsenic removal by electrocoagulation. The model predicted reasonably good arsenic removal (error<2%) from low (0.288 mg/L) and high (0.882 mg/L) initial arsenic concentrations in presence of naturally cooccurring solutes in the groundwater. For the range of operating variables studied, optimum removal of arsenic (98.56%) is obtained at higher arsenic concentration (1.18 mg/L), lower volume (1 L), higher current (3 A), and higher current processing time (120 s).     

Ethephon‐induced fractional changes of pectic polysaccharides in developing cape gooseberry (Physalis peruviana L) fruits

Pectic polysaccharides extracted from fruit tissue of cape gooseberry (Physalis peruviana L) at different maturity levels were fractionated and analyzed for galacturonic acid backbone molecules. Preharvest spray of the fruits at 7 days old with ethephon resulted in a higher accumulation of water‐soluble and oxalate‐soluble pectic fractions than non‐treated fruits, while this treatment effectively enhanced the polygalacturonase enzyme activity necessary for maintenance of pectin degradation. Treatment with ethephon not only enhanced the solubilization rate but also resulted in a net increase in total pectic polymer content in developing cape gooseberry fruits. Copyright © 2005 Society of Chemical Industry     

Room temperature ammonia sensor based on jaw like bis-porphyrin molecules

A jaw-like bis-porphyrin (bis-TPP) molecule was synthesized anchoring of two porphyrin molecules to a benzene ring at the meta positions through the ester linkage. The bis-TPP molecule and its zinc-derivative (Zn-bis-TPP) were spin-coated on glass surfaces to construct two chemiresistive room temperature NH₃ gas sensors. Both the films showed high selectivity, reproducibility and reversibility in sensing NH₃ gas (5–40 ppm) in air. The sensing characteristics of the Zn-bis-TPP films (response (2 s) and recovery (2.5 min) times; linear response (952%)) were better than that of the bis-TPP films (response (8 s) and recovery (7.5 min) times; linear response (131%)). This is attributed to the amorphous nature of the former.     

Investigation on the electrical characteristics of sol-gel derived Pb1.05(Zr0.53Ti0.47)O3 thin films

Abstract

Lead zirconate titanate (PZT) thin films with composition Zr/Ti ～ 0.53/0.47 were deposited by the sol-gel technique. The films were characterized in terms of its polarization relaxation, fatigue and imprint characteristics. We have found that the polarization relaxation is due to the presence of a depolarization field which increases dramatically with the rise in temperature. Improved fatigue performance was observed when the film was fatigued with higher frequency. The direction of imprint depends on the state of polarization. With the increase in net polarization, the trapped charge density at the film-electrode interface increases which leads to imprint characteristics. Also the imprint increases considerably with the rise in temperature. Finally, we have made an attempt to correlate simultaneously fatigue, polarization relaxation, and imprint characteristics with the presence of mobile charge defects (viz. V_o) and defect dipoles (viz. V_Pb – V_o) in the film.