Molecular features of sulfonic acids used for synthesis of overbased detergent additives

Overbased calcium sulfonates are used in many modern oil formulations to provide cleaning action and to neutralize the organic acids formed during combustion, preventing corrosion. The performance of detergents is related to their molecular structure, which is generally known only as a chemical category. In the present work, nuclear magnetic resonance (NMR) spectroscopy and electrospray ionization mass spectrometry are used to analyze the molecular structure of three alkyl‐benzene sulfonic acids in detail. Some important molecular features were obtained by elaborating the NMR signal intensities, such as the number and positions of alkyl substituents on the benzene ring, the distribution of alkyl chain lengths and the mole fraction of 1‐phenyl isomers (synthesized by alkylation of benzene with α‐olefin). Ion‐trap mass spectrometry is used to obtain the mass spectrometry/mass spectrometry (MS²) spectra of the principal molecular ions. By choosing suitable molecular ions, MS² spectra can ascertain the presence of different substituted benzene isomers within a mixture because the MS² spectra show specific fragments due to the number of alkyl substituents on the aromatic ring. Copyright © 2006 John Wiley & Sons, Ltd.     

An a posteriori error estimator for model adaptivity in electrocardiology

We introduce an a posteriori modeling error estimator for the effective computation of electric potential propagation in the heart. Starting from the Bidomain problem and an extended formulation of the simplified Monodomain system, we build a hybrid model, called Hybridomain, which is dynamically adapted to be either Bi- or Monodomain ones in different regions of the computational domain according to the error estimator. We show that accurate results can be obtained with the adaptive Hybridomain model with a reduced computational cost compared to the full Bidomain model. We discuss the effectivity of the estimator and the reliability of the results on simulations performed on real human left ventricle geometries retrieved from healthy subjects.     

CC-RANSAC: Fitting planes in the presence of multiple surfaces in range data

Range sensors, in particular time-of-flight and stereo cameras, are being increasingly used for applications such as robotics, automotive, human-machine interface and virtual reality. The ability to recover the geometrical structure of visible surfaces is critical for scene understanding. Typical structured indoor or urban scenes are often represented via compositional models comprising multiple planar surface patches. The RANSAC robust regression algorithm is the most popular technique to date for extracting individual planar patches from noisy data sets containing multiple surfaces. Unfortunately, RANSAC fails to produce reliable results in situations with two nearby patches of limited extent, where a single plane crossing through the two patches may contain more inliers than the “correct” models. This is the case of steps, curbs, or ramps, which represent the focus of our research for the impact they can have on cars’ safe parking systems or robot navigation. In an effort to improve the quality of regression in these cases, we propose a modification of the RANSAC algorithm, dubbed CC-RANSAC, that only considers the largest connected components of inliers to evaluate the fitness of a candidate plane. We provide experimental evidence that CC-RANSAC may recover the planar patches composing a typical step or ramp with substantially higher accuracy than the traditional RANSAC algorithm.     

Multiwall carbon nanotubes as MRI contrast agents for tracking stem cells

In this study we investigate the potential of multiwall carbon nanotubes (MWCNTs) with low metal impurities (2.57% iron) as magnetic resonance imaging (MRI) contrast agents. Taking into account probable aggregation at high MWCNTs concentration analysis shows that the r(2) relaxivity of MWCNTs in 1% agarose gels at 19?°C is 564 ± 41 s(-1) mM(-1); this is attributed to both the presence of iron oxide impurities and also to the carbon MWCNT structure itself. Stem cells were labelled with MWCNTs to demonstrate the effectiveness of MWCNTs as MRI contrast agents for cellular MRI. The MWCNTs did not impair cell viability or proliferation. These results suggest that the MRI contrast agent properties of the MWCNTs could be used in vivo for stem cell tracking/imaging and during MWCNT-mediated targeted electro-chemotherapy of tumours.     

Sputum metalloproteinase-9/tissue inhibitor of metalloproteinase-1 ratio correlates with airflow obstruction in asthma and chronic bronchitis

Asthma and chronic bronchitis are inflammatory diseases with extracellular matrix (ECM) remodeling and collagen deposition. Collagen homeostasis is controlled by metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). We evaluated MMP and TIMP balance in induced sputum of 10 control, 31 untreated asthmatic, and 16 chronic bronchitic subjects. We first performed zymographic analysis to identify the profile of MMPs. Zymography revealed a similar MMPs profile in all populations studied and that MMP-9 was the major enzyme released. We then measured, using enzyme immunoassay, the concentrations of MMP-9 and of its inhibitor TIMP-1 and evaluated whether airflow limitation may be associated with an imbalance between these enzymes. MMP-9 and TIMP-1 concentrations were greater in sputum of patients with asthma and chronic bronchitis than in control subjects. The molar ratio between MMP-9 and TIMP-1 was lower in asthmatics and chronic bronchitics than in control subjects, and positively correlated with FEV1 values. In asthma, MMP-9 levels were significantly correlated with the number of macrophages and neutrophils. This study shows that airway inflammation in asthma and chronic bronchitis is associated with an imbalance between MMP-9 and TIMP-1 which may have a role in the pathogenesis of ECM remodeling and airflow obstruction.     

Evaluating the field bus data link layer by a Petri net-basedsimulation

The performance of the data link layer of the field bus, an emerging LAN architecture for control systems presently under standardization, is discussed and evaluated. Some aspects of the communication mechanism are presented, referring to the use of the two kinds of tokens of the protocol and pointing out their main features and the advantages and disadvantages offered by each one. The protocol was specified by extended timed Petri-nets and was evaluated by a suitable simulation tool. The results provide some criteria according to which the designer can choose, among the various mechanisms made available by the standard proposal, those which provide the most efficient solution for the scenario being considered     

Pressure-Driven Demand and Leakage Simulation for Water Distribution Networks

Increasingly, water loss via leakage is acknowledged as one of the main challenges facing water distribution system operations. The consideration of water loss over time, as systems age, physical networks grow, and consumption patterns mature, should form an integral part of effective asset management, rendering any simulation model capable of quantifying pressure-driven leakage indispensable. To this end, a novel steady-state network simulation model that fully integrates into a classical hydraulic representation, pressure-driven demand and leakage at the pipe level is developed and presented here. After presenting a brief literature review about leakage modeling, the importance of a more realistic simulation model allowing for leakage analysis is demonstrated. The algorithm is then tested from a numerical standpoint and subjected to a convergence analysis. These analyses are performed on a case study involving two networks derived from real systems. Experimentally observed convergence/error statistics demonstrate the high robustness of the proposed pressure-driven demand and leakage simulation model.     

Influence of the internal inertia of the building envelope on summertime comfort in buildings with high internal heat loads

The aim of this study was to assess the influence of thermal mass placed on the inner side of the building envelope, described as the dynamic internal areal heat capacity (International Standard ISO 13786), on the summertime thermal comfort in buildings characterised by high internal heat loads.To that aim, simultaneous monitoring was carried out on rooms with high internal heat loads (school classrooms), varying the internal inertia of the envelope through the introduction of an insulating panel on the interior side. Analytical assessment was performed in order to include different inertia values and combinations of both external and internal heat loads.The study allowed the threshold values of internal areal heat capacity to be determined with respect to the different periodic transmittance values of the walls, assessed according to the adaptive thermal comfort model described in Standard EN15251.These values could be adopted in energy saving regulations which, being based on semi-stationary calculation models, tend to consider the performance of building envelopes as analogous even if there is different thermal inertia.     

Influence of Heterogeneous Magnetism on Magneto-Optical Properties

The influence of inhomogeneity on magnetic materials is considered; in particular, we examine how it affects the magneto-optical (MO) response of films and multilayers. From ab initio calculations of the band structure, the optical conductivity tensor is derived, providing the basis for computing the MO spectra. The presence of magnetic nanoprecipitates is taken into account by modeling the system as an effective medium or as an infinitely thin layered structure. A possible depth concentration distribution of the magnetic species is also accounted for, by considering the structure as a sequence of layers. This formalism is applied to some real systems constituted by magnetic particles dispersed in a hosting nonmagnetic matrix. The agreement between theoretical and measured MO Kerr effect spectra supports the validity of the model and establishes its predictive power, suggesting that the analysis of experimental MO spectra can provide information not only on the magnetic, but also on the structural properties of heterogeneous magnetic systems.     

A Novel Genetic Variant in the WFS1 Gene in a Patient with Partial Uniparental Mero-Isodisomy of Chromosome 4

Wolfram syndrome is a rare autosomal recessive disorder characterized by optic atrophy and diabetes mellitus. Wolfram syndrome type 1 (WFS1) is caused by bi-allelic pathogenic variations in the wolframin gene. We described the first case of WFS1 due to a maternal inherited mutation with uniparental mero-isodisomy of chromosome 4. Diabetes mellitus was diagnosed at 11 years of age, with negative anti-beta cells antibodies. Blood glucose control was optimal with low insulin requirement. No pathogenic variations in the most frequent gene causative of maturity-onset diabetes of the young subtypes were detected. At 17.8 years old, a rapid reduction in visual acuity occurred. Genetic testing revealed the novel homozygous variant c.1369A>G; p.Arg457Gly in the exon 8 of wolframin gene. It was detected in a heterozygous state only in the mother while the father showed a wild type sequence. In silico disease causing predictions performed by Polyphen2 classified it as “likely damaging”, while Mutation Tester and Sift suggested it was “polymorphism” and “tolerated”, respectively. High resolution SNP-array analysis was suggestive of segmental uniparental disomy on chromosome 4. In conclusion, to the best of our knowledge, we describe the first patient with partial uniparental mero-isodisomy of chromosome 4 carrying a novel mutation in the wolframin gene. The clinical phenotype observed in the patient and the analysis performed suggest that the genetic variant detected is pathogenetic.