A comparison of the shake test, optical density, L/S ratio (planimetric and stechiometric) and PG for the assessment of fetal lung maturity

Our aim was to determine the diagnostic accuracy and reliability of four tests for the assessment of fetal lung maturity (FLM): shake test, optical density at 650 nm (OD650), lecithin to sphingomyelin ratio (L/S) by planimetry and stechiometry, and presence of phosphatydylglycerol. Amniotic fluid was obtained from 74 patients at various gestational ages. The shake test and the OD650 were performed according to published methods L/S was determined by TLC (thin-layer chromatography) and the ratio assessed by planimetry and stechiometrically by measurement of organic phosphorus from the chromatographic spots. PG was assessed similarly by TLC. When correlated with gestational age at amniocentesis, all tests correlated positively: shake test (r = 0.46, p < 0.005); OD650 (r = 0.31, p < 0.005); planimetric L/S (r = 0.77, p < 0.005); stechiometric L/S (r = 0.52, p < 0.005) and PG (r = 0.54, p < 0.005). The diagnostic accuracy of each test was as follows: the shake test and the OD650 had a sensitivity of 50%, while the steciometric L/S had a sensitivity of 75%, the planimetric L/S and the presence of PG were 100%. All four tests demonstrated a specificity greater than 64%, the highest for the PG presence being (83%) and the shake test (86%). Predictive negative values for lung maturity were > 93% for all tests, with the highest for the planimetric L/S and presence of PG being (100%). The study confirms that the determination of L/S ratio is still superior to other tests in terms of overall diagnostic accuracy. In addition, it was found that presence of PG was highly associated with the absence of respiratory complications in the newborn.     

A parallel evolutionary algorithm to optimize dynamic memory managers in embedded systems

For the last 30 years, several dynamic memory managers (DMMs) have been proposed. Such DMMs include first fit, best fit, segregated fit and buddy systems. Since the performance, memory usage and energy consumption of each DMM differs, software engineers often face difficult choices in selecting the most suitable approach for their applications. This issue has special impact in the field of portable consumer embedded systems, that must execute a limited amount of multimedia applications (e.g., 3D games, video players, signal processing software, etc.), demanding high performance and extensive memory usage at a low energy consumption. Recently, we have developed a novel methodology based on genetic programming to automatically design custom DMMs, optimizing performance, memory usage and energy consumption. However, although this process is automatic and faster than state-of-the-art optimizations, it demands intensive computation, resulting in a time-consuming process. Thus, parallel processing can be very useful to enable to explore more solutions spending the same time, as well as to implement new algorithms. In this paper we present a novel parallel evolutionary algorithm for DMMs optimization in embedded systems, based on the Discrete Event Specification (DEVS) formalism over a Service Oriented Architecture (SOA) framework. Parallelism significantly improves the performance of the sequential exploration algorithm. On the one hand, when the number of generations are the same in both approaches, our parallel optimization framework is able to reach a speed-up of 86.40× when compared with other state-of-the-art approaches. On the other, it improves the global quality (i.e., level of performance, low memory usage and low energy consumption) of the final DMM obtained in a 36.36% with respect to two well-known general-purpose DMMs and two state-of-the-art optimization methodologies.     

Influence of the processing parameters and composition on the thermal stability of PLA/nanoclay bio‐nanocomposites

Poly(lactic acid) (PLA) is one the most promising bio‐based and biodegradable polymer. However, its low thermal stability limits the range of applications and complicates its transformation via the most industrial common processes. The novelty of this work is studying the thermal stability of PLA and PLA/clay nanocomposites during use, as a function of the composition and using a wide range of extrusion and injection moulding processing parameters. To improve the thermal stability of the PLA, laminar silicates containing different organomodifications have been added (Cloisite 20A and Cloisite 30B). The results show that the processing conditions and composition define the morphology of the bio‐nanocomposites, which plays key role in defining final thermal properties of the material. In general, clays improve the thermal stability of the processed material, increasing the degradation temperature and decreasing the degradation rate under a wide range of processing conditions. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40747.     

A REMPI method for the ultrasensitive detection of NO and NO2 using atmospheric pressure laser ionization mass spectrometry

We report on the development of a quasi-simultaneous highly selective method for NO and NO2 detection at the ultratrace level. Atmospheric pressure laser ionization (APLI), recently introduced by our group, is used to detect both compounds at low parts per trillion by volume (pptv) mixing ratios. APLI is based on resonance-enhanced multiphoton ionization mass spectrometry. Two-color pump-probe experiments employing a single excimer pumped dye laser combination allow for the ultrasensitive measurement of NO and NO2 within a narrow range of maximum pumping efficiency of the laser dye Coumarin 120. NO is detected via excitation of the long-lived A 2sigma+ (nu' = 1) level at 215.36 nm and subsequently ionized with 308-nm radiation provided by the excimer pump laser. NO2 is ionized after double resonant excitation of the A2B1 and 3psigma manifolds in a (1 + 1' + 1(')) process using 431.65 + 308 nm. The selectivity of the NO measurement exceeds 2,000 with respect to NO2 and N2O5. For NO2, a selectivity of >3,000 with respect to N2O5 and organic nitrates is observed. The current APLI detection limit of NO and NO2 is 0.5 and 5 pptv, respectively, with a 20-s integration time.     

Lithium Phosphonate Functionalized Polymer Coating for High-Energy Li[Ni0.8Co0.1Mn0.1]O2 with Superior Performance at Ambient and Elevated Temperatures

High-energy Ni-rich lithium transition metal oxides such as Li[Ni_0.8Co_0.1Mn_0.1]O₂ (NCM₈₁₁) are appealing positive electrode materials for next-generation lithium batteries. However, the high sensitivity toward moist air during storage and the high reactivity with common organic electrolytes, especially at elevated temperatures, are hindering their commercial use. Herein, an effective strategy is reported to overcome these issues by coating the NCM₈₁₁ particles with a lithium phosphonate functionalized poly(aryl ether sulfone). The application of this coating allows for a substantial reduction of lithium-based surface impurities (e.g., LiOH, Li₂CO₃) and, generally, the suppression of detrimental side reactions upon both storage and cycling. As a result, the coated NCM₈₁₁-based cathodes reveal superior Coulombic efficiency and cycling stability at ambient and, particularly, at elevated temperatures up to 60 ° C (a temperature at which the non-coated NCM₈₁₁ electrodes rapidly fail) owing to the formation of a stable cathode electrolyte interphase with enhanced Li⁺ transport kinetics and the well-retained layered crystal structure. These results render the herein presented coating strategy generally applicable for high-performance lithium battery cathodes.     

Teaching model-driven engineering from a relational database perspective

We reinterpret MDE from the viewpoint of relational databases to provide an alternative way to understand, demonstrate, and teach MDE using concepts and technologies that should be familiar to undergraduates. We use (1) relational database schemas to express metamodels, (2) relational databases to express models, (3) Prolog to express constraints and M2M transformations, (4) Java tools to implement M2T and T2M transformations, and (5) Java to execute transformations. Application case studies and a user study illuminate the viability and benefits of our approach.     

Surface functionalization of polyolefin films via the ultraviolet‐induced photografting of acrylic acid: Topographical characterization and ability for binding antifungal agents

The photoinduced graft copolymerization of acrylic acid with ultraviolet radiation onto films of poly(vinyl chloride), polypropylene, and polyethylene was studied. Benzophenone was used as the initiator for most of the experiments performed. The percentage of grafting was determined by gravimetric measurements, and the characterization of the grafted films was carried out by chemical analysis (Fourier transform infrared spectroscopy, volumetric titration, and dye adsorption). In all samples, the grafted yield increased with the ultraviolet exposure time. High levels of grafting were obtained at room temperature. In addition, optical and atomic force microscopy allowed the topography of the modified films to be studied as a function of the reaction time. The pendant functional groups that were grafted were then used to bind antifungal agents, such as natamycin and crystal violet, and the antifungal properties of the films were demonstrated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:2254–2263, 2006