Aromatization of [1-14C]heptane over “nonacidic” platinum-alumina catalyst

[1-¹⁴C]Heptane was aromatized under 5 atm pressure over a “nonacidic” 3% platinum on alumina catalyst maintained at 500 °C. The reactant was pumped in at a HLSV of 0.88, and the hydrogen-to-heptane mole ratio was 5.1. The samples of product were collected (one during the first 90 min and another during the next 90 min), the toluene was separated from the respective samples, and the radioactivity in each position of the toluene was determined by a degradation sequence. The distribution of radioactivity in sample 1 was as follows: in position 1–2.6%, 2–38.6%; 3–14.5%; 4–4.2%, and in the methyl group—40.1%. Approximately similar distribution of radioactivity was found in sample 2. 1,6-Ring closure is the most important pathway leading to the formation of toluene from [1-¹⁴C]heptane; lesser amounts of repetitive, 1,5-ring closure and hydrogenolysis, and bond shift reactions followed by 1,6-ring closure and dehydration can explain the distribution of radioactivity. The participation of 1,7-ring closure in the reaction is also indicated.     

A novel electromyographic signal simulator for muscle contraction studies

Mathematical simulation has been widely used in biomedical and biological sciences. In the case of the surface electromyographic (SEMG) activity, some models have been proposed aiming to study muscle contraction strategies that are used during different tasks and conditions. Most of SEMG simulators are based on energy modulation of a Gaussian noise. This work proposes a novel simulator in which the user-defined parameters are associated with the motor units (MUs) recruitment and their firing rate. Comparison between the mean spectrum of real SEMG signals collected in isometric contraction of the muscle biceps brachii and the mean spectrum obtained from simulated SEMG signals showed a good agreement, pointing the proposed simulator seems to be capable to generate consistent electromyographic signals in time and frequency domains and that can be used in many studies, in particular in the evaluation of automatic methods aimed to detect muscular contraction.     

Lagrangean relaxation with clusters for point-feature cartographic label placement problems

This paper presents two new mathematical formulations for the point-feature cartographic label placement problem (PFCLP) and a new Lagrangean relaxation with clusters (LagClus) to provide bounds to these formulations. The PFCLP can be represented by a conflict graph and the relaxation divides the graph in small subproblems (clusters) that are easily solved. The edges connecting clusters are relaxed in a Lagrangean way and a subgradient algorithm improves the bounds. The LagClus was successfully applied to a set of instances up to 1000 points providing the best results of those reported in the literature.     

Higher incidence of Gastrospirillum sp. in swine with gastric ulcer of the pars oesophagea

Gastric ulcer in swine is characterized by an area of acid-peptic digestion, occurs usually in the pars oesophagea of the stomach, and has unknown etiopathogenesis. The present work was carried out to investigate the prevalence of the newly described spiral-shaped microorganism Gastrospirillum sp. ("Gastrospirillum suis") in stomachs of abattoir pigs with and without gastric ulcer. Stomachs were removed from 32 consecutive pigs presenting apparently normal mucosa and from 32 additional consecutive pigs presenting frank, chronic gastric ulcer of the pars oesophagea. Fragments of antral, oxyntic, cardiac and pars oesophagea regions were taken from each stomach and processed for histology and for identification of Gastrospirillum sp. in tissue sections. The microorganisms were identified mainly in the mucous layer and in gastric foveolas of the antral and oxyntic mucosa. Forty pigs (62.5%) were positive for Gastrospirillum sp.; among them, 27 (67.5%) had gastric ulcer, and 13 (32.5%) had no ulcer. Twenty-four pigs (37.5%) were negative for Gastrospirillum sp.; among them, five (20.8%) presented with gastric ulcer, and 19 (79.2%) had no ulcer. There was a significant difference between pigs with and without gastric ulcer in regard to the presence of Gastrospirillum sp. (P < 0.01). The spiral-shaped microorganism Gastrospirillum sp. that inhabits the stomach of pigs should be considered a possible factor connected with the etiopathogenesis of swine gastric ulcer.     

Transmission power and data rate aware routing on wireless networks

Wireless networks can vary both the transmission power and modulation of links. Existing routing protocols do not take transmission power control (TPC) and modulation adaptation (also known as rate adaptation – RA) into account at the same time, even though the performance of wireless networks can be significantly improved when routing algorithms use link characteristics to build their routes. This article proposes and evaluates extensions to routing protocols to cope with TPC and RA. The enhancements can be applied to any link state or distance vector routing protocols. An evaluation considering node density, node mobility and link error show that TPC- and RA-aware routing algorithms improve the average latency and the end-to-end throughput, while consuming less energy than traditional protocols.     

Effects of long-term in vitro exposure to phosphodiesterase type-3 inhibitors on follicle and oocyte development

Germinal vesicle (GV)-stage oocytes retrieved from antral follicles undergo nuclear maturation in vitro, which typically occurs prior to cytoplasmic maturation. Short-term culture with meiotic inhibitors has been applied to arrest oocytes at the GV stage aiming to synchronize nuclear and ooplasmic maturity. However, the results obtained are still far from the in vivo situation. In order to acquire competence, immature oocytes may require meiotic arrest in vitro for a more extended period. The phosphodiesterase type 3-inhibitor (PDE3-I) is a potent meiotic arrester. The effects of a prolonged culture with PDE3-I on oocyte quality prior to and after reversal from the inhibition are not known. This study tested the impact of long-term in vitro exposure of two PDE3-Is, org9935 and cilostamide, on oocytes using a mouse follicle culture model. The results showed that PDE3-I (maximum of 10 microM) during a 12-day culture of follicle-enclosed oocytes did not alter somatic cell proliferation, differentiation or follicle survival. In addition, the steroid production profile was not significantly modified by a 12-day exposure to PDE3-I. The recombinant human chorionic gonadotrophin/recombinant human epidermal growth factor stimulus induced a characteristic normal progesterone peak of luteinization and normal mucification of the cumulus cells, while the enclosed oocyte remained blocked at the GV stage. In vitro maturation of denuded or cumulus-enclosed oocytes derived from org9935- or cilostamide-exposed follicles progressed through meiosis and formed morphologically normal meiotic spindles with chromosomes properly aligned at the equator. In conclusion, long-term culture with PDE3-I was harmless to somatic cell function, differentiation, oocyte growth and maturation. Our results suggested that PDE3-I can be applied when extended oocyte culture is required to improve ooplasmic maturation.     

Wavelet-based analysis of ultrasonic longitudinal and transverse pulses in cement-based materials

Ultrasonic pulse velocity has been used for decades to detect localized damage and to estimate concrete properties. More recent applications aim at diffuse damage characterization, such as environmental and mechanical damage. In most applications the methodology to calculate pulse speed is a very important issue. This work, applying continuous wavelet transform (CWT) to construct time-frequency signal representations, calculates frequency-dependent velocity of longitudinal and transverse ultrasonic pulses using wavelet scales. The method is applied to a total of 14 specimens of 5 different mixes and frequency-dependent velocities are calculated using four wavelet families. The CWT capability to decompose the inquiring pulse spectrum and analyze phase velocities is discussed with regard to wavelet, pulse type, and mixture. Frequency-dependent velocity of longitudinal pulses at lower frequencies (from 100 kHz up to 250 kHz) was proven to be much more sensitive to mix proportions than transverse pulses.     

High resolution NMR study of tropical fruit seed starches

The nuclear magnetic resonance spectroscopy (NMR) studies of starches obtained by fruit seeds such as melon and watermelon were carried out as an analytical methodology to understand the molecular dynamic behavior. This study was also accompanied by the conventional X‐ray diffraction and thermal analysis. The NMR results give us a complete behavior of the samples at the molecular level. Thus, the information obtained from NMR will complement the data obtained from X‐ray and thermal analysis allowing us having responses on samples structure and dynamical behavior. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Controlling the phase stability of polymer blends through the introduction of impenetrable interfaces

In this work, the effect of the introduction of modified solid surfaces into polymer blends on the phase‐separation process was investigated. Glass fibers with surfaces having different chemistries were introduced into polystyrene–poly(methyl methacrylate) blends. The glass fibers used either had fully hydrated surfaces or had surfaces covered with a random copolymer, poly(styrene‐co‐methyl methacrylate). The copolymer was synthesized by free‐radical polymerization of styrene and methyl methacrylate in the presence of previously vinyl silane‐treated glass fibers. The copolymerization and grafting procedures were investigated by FTIR and thermal analysis. Blends containing the fibers were studied using FTIR microscopy and optical microscopy. FTIR microscopy results showed that the composition of the phases in the blends was shifted by using fibers with different surface chemistries. Fibers with grafted copolymers were capable of narrowing the immiscibility region in the phase diagram, while fully hydrated fibers were able to expand the gap. It was proposed that interfacial interactions regulated by a hydrophilic–hydrophobic type of forces were responsible for guiding the described phase‐separation process. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1619–1627, 2003     

Continuous polymerization in tubular reactors with prepolymerization: Analysis using two‐dimensional phenomenological model and hybrid model with neural networks

Continuous polymerization processes have advantages when large amounts of product are required; moreover, higher quality can be obtained because of the elimination of variability between batches. Tubular reactors are economically attractive because of their simple geometry and high heat exchange area; however, they are not commonly used for commercial purposes, mainly because of the large radial profiles. This study elucidates the operation of this kind of reactors in three different ways: first a detailed two‐dimensional mathematical model was developed, in which a complete visualization of all axial and radial profiles is possible, allowing a safe analysis at different operating conditions. In a second step a system composed of a continuously stirred tank reactor in series with a tubular reactor was used. A reduction in radial profiles can be clearly observed when prepolymerization is taken into account, improving both the homogeneity and the end properties of the polymer. In a third approach neural networks (NNs) were used in parallel with a one‐dimensional model. The objective of this study was to illustrate how NNs can improve the prediction capability when it is not possible to build a reliable model because of uncertainties in parameters and incomplete knowledge of the system. The NNs generated good results, showing that the hybrid model was able to accurately simulate the reactor, even when uncertainty in kinetic and diffusional parameters was imposed to the model. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 871–882, 2004