High‐resolution solid‐state NMR investigation of the filler–rubber interaction: 2. High‐speed [1H] magic‐angle spinning NMR spectroscopy in carbon‐black‐filled polybutadiene

This work investigates the behaviour of elastomeric chains (polybutadienes of identical molecular weight but different microstructures) in the close vicinity of carbon black surfaces in order to attain a better understanding of the structure and properties of interphases. Elastomer–filler interactions are assessed through the study of the thermal properties and NMR relaxation characteristics of the corresponding materials. Three series of samples were compared: pure polymers, raw polymer–filler blends (filler loading ratio: 50 phr) and solvent‐extracted blends (so as to get rid of any polymer which is not under the influence of the solid surface). While differential scanning calorimetry points to the existence of an elastomer fraction which is not detected as undergoing the glass transition, ie is strongly immobilized, [¹H] high‐resolution high‐speed magic‐angle spinning solid‐state NMR provides information on the effect exerted by polymer–filler interactions on the mobility of the various constitutive species of the macromolecular backbone. A systematic study of the evolution of the spectral lines yielded by the samples indicates that 1,2‐polybutadiene moieties have a particular affinity towards the carbon black surface which suggests the occurrence of specific interactions at the elastomer–filler interface. © 2001 Society of Chemical Industry     

Comparative proximal and mineral analysis of iguana,poultry and beef meats

Raw meat samples from iguana, poultry and beef cattle specimens were used to compare proximal (g/100 g) and mineral (mg/100 g) composition. Iguana meat was obtained by dissecting whole specimens (Iguana iguana) captured at a ranch (n = 20). Thighs and breasts were separated from broiler (either chilled or frozen) carcasses (n = 20), and deboned to represent chicken meat samples, whereas 2.5-cm-thick longissimus (ribeyes) steaks were removed from carcasses and frozen to represent beef of several breed types (n = 20). The one-way analysis of variance performed by the least squares method (LS Means) showed specie affected significantly (p > 0.05) all composition variables under study. Moisture content did not differ between iguana and chicken meats (74.7 y 74.9%, respectively) whereas beef samples had the lowest water content (73%) (p < 0.01). LS means for protein content showed beef samples (22.3%) were highest (p < 0.05) in this nutrient, iguana meat being intermediate (20.8%). Chicken meat presented the highest amount of total lipids (7.75 +/- 0.20 g/100 g) (p < 0.01) followed by iguana (3.49 +/- 0.12 g/100 g) and beef (2.57 +/- 0.20 g/100 g). Ash and most individual minerals were more concentrated in iguana meat, except for K and Zn that were more abundant in beef samples. Non-significant differences in Mg, Na, Cu or Mn contents were detected between chicken and beef samples. It was concluded that iguana meat could be an alternate source of protein and minerals as compared to those of traditional meat species.     

Meat quality of steers finished on autumn grass, grass silage or concentrate-based diets

The objective of this experiment was to determine the effect of varying the proportions of autumn grass and concentrates and grass silage and concentrates on the quality of meat from cattle with similar rates of carcass growth. Fifty continental crossbred steers were assigned to five treatments. The experimental diets offered were (1) grass silage ad libitum plus 4 kg concentrate (SC), (2) 1 kg hay plus 8 kg concentrate (CO), (3) 6 kg grass dry matter (DM) plus 5 kg concentrate (CG), (4) 12 kg grass DM plus 2.5 kg concentrate (GC) and (5) 22 kg grass DM (GO). The experiment lasted 85 days after which all animals were slaughtered. The right side m. longissmus dorsi was excised from all animals 24 h post slaughter for assessment of meat quality. Treatments SC and CO resulted in animals with whiter (P<0.05) subcutaneous and kidney/channel fat than all other treatments. There was an interaction (P<0.05) between ageing time and treatment with treatment GC having higher (P<0.05) tenderness, texture and acceptability values after 2 days ageing, but not after 7 or 14 days ageing. It is concluded that supplementing grass with low levels of concentrate produced the most tender and acceptable meat at 2 days post mortem, but that further ageing eliminated all treatment effects on eating quality of beef.     

Tenderisation of the dog cockle (Glycymeris glycymeris) meat by polyphosphates

Clams are widely used in the preparation of several seafood dishes but there are still a few bivalve species which have not been extensively used. Among these species is dog cockle (Glycymeris glycymeris), which is a major by-catch of surf clam (Spisula solida) fishing. However, dog cockle has a low commercial value because its texture is too tough after cooking. This study was initiated to find the best way of tenderising the meat of this species to make it suitable for human consumption. Based on preliminary trials using different tenderising products, a mixture of sodium tripolyphosphate and sodium chloride (3% and 1.5% respectively) was considered the most effective. The optimization of the processing parameters (time and temperature) was done by response surface methodology. According to the sensory analysis, objective texture evaluation and phosphate determinations the optimum conditions for the tenderisation process were an immersion time of 3 h at a temperature of 20  °C. The tenderised meat was used in the preparation of two types of canned products (light brine and a pickling sauce known as "escabeche"), which were evaluated by a taste panel and judged satisfactory.     

Electropolymerization of pyrrole and immobilization of glucose oxidase in a flow system: influence of the operating conditions on analytical performance

The in situ potentiostatic electropolymerization of pyrrole (Py) on a Pt electrode in a thin-layer amperometric cell and the entrapment of the enzyme glucose oxidase (GOx) for the determination of glucose are reported. Polypyrrole (PPy) is directly formed by continuous passage of a buffered solution of the monomer (0.4 M) and enzyme (250 U mL-1) at pH 7 at a flow rate of 0.05-0.1 mL min-1 under a constant applied potential of +0.85 V vs Ag/AgCl decreases. The electrosynthesis of PPy by injection of 500 microL of a Py + GOx solution in a carrier electrolyte consisting of 0.05 M phosphate buffer and 0.1 M KCl at pH 7.0 was also assayed. The influence of the electropolymerization conditions on the analytical response of the sensor to glucose was investigated. The analytical performance of the PPy/GOx sensor was also studied in terms of durability and storage life, as well as selectivity against electroactive species such as ascorbic acid and uric acid as a function of the thickness of the polymer film formed.     

Stroke: a stranger among the people

INTRODUCTION: Lack of awareness of warning signs of stroke is a factor that contribute to late patient arrival to the emergency department. OBJECTIVE: The goal of this pilot study was to determine the baseline knowledge of stroke among the population (terminology, signs-symptoms, risk factors and attitude) prior to educational campaigns. PATIENTS AND METHODS: A population-based interview using closed-ended questions was conducted by neurologists among 100 users of the Vall d'Hebron's Primary Health Center, randomly sampled. RESULTS: In our population a 9% unknowns totally the disease, of the remainder, 42% has a good knowledge of signs-symptoms and 46% of risk factors. Only 22% of the sample has good global knowledge of the disease. If suffering a stroke this population should seek medical attention through 911 (46.2%) or come directly to the emergency department (50.5%). If symptoms were gone away, transient ischemic attack (TIA), appears a trend to contact primary physicians (59.3%). Respondents aged > 65 years were less likely to recognize symptoms (p = 0.001) and to consider stroke as an emergency. Respondents with an affected relative (50.5%) tend to locate more exactly the disease at the brain (p = 0.05) and to arrive earlier to the emergency department (p = 0.045), than those with non-affected relatives. CONCLUSIONS: Less than a quarter of our population have a good knowledge of the disease. Stroke is considered an emergency unlike TIA. The information about stroke is theoretically associated with early presentation to the emergency department. These results permit a redesign of the questionnaire to conduct a second phase of the study and generalize them for the Spanish population.     

Development and validation of a high-performance liquid chromatography-mass spectrometry assay for determination of amphetamine, methamphetamine, and methylenedioxy derivatives in meconium

A procedure based on liquid chromatography-mass spectrometry (LC-MS) is described for determination of amphetamine, methamphetamine, and methylendioxy derivatives in meconium, using 3,4-methylendioxypropylamphetamine as internal standard. The analytes were initially extracted from the matrix by 17 mM methanolic HCl. Subsequently, a solid-phase extraction with Bondelut Certify columns was applied. Chromatography was performed on a C(18) reversed-phase column using a linear gradient of 10 mM ammonium bicarbonate, pH 9.0-methanol as a mobile phase. Analytes were determined in LC-MS single ion monitoring mode with an atmospheric pressure ionization-electrospray interface. The method was validated in the range 0.005-1.00 microg/g using 1 g of meconium per assay. Mean recoveries ranged between 61.1 and 87.2% for different analytes. The quantification limits were 0.005 microg/g meconium for amphetamine, methamphetamine, and 4-hydroxy-3-methoxymethamphetamine and 0.004 microg/g meconium for 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, 3,4-methylenedioxyethylamphetamine, and N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine. The method was applied to analysis of meconium in newborns to assess eventual fetal exposure to amphetamine derivatives.     

Silica-grafted polyisobutylene and butyl rubber

Summary Silica surfaces have been modified by reaction with ClSi(CH₃)₂CH₂-CH₂-C₆H₄CH₂Cl (I) and the solids were used in conjunction with Et₂AlCl to initiate the surface-graft polymerization of isobutylene. Experimental conditions have been defined to obtain respectable grafting rates, grafting ratios and grafting efficiencies.     

A high resolution workstation prototype for diagnosis of digital mammograms

The development of a total digital high resolution mammography display system must meet a number of requirements that remain a challenge nowadays, most probably because of the special nature of breast imaging. In this paper, we discuss our particular approach to address some problems concerning the complexity of soft-copy diagnosis in digital mammography, such as image quality and user interface evaluation. Based on the experience obtained in the previous implementation of a medical image browser, a more ambitious project is being developed at the Department of Radiology of the University of Santiago de Compostela (Spain) in collaboration with the Department of Medical Informatics of INTELSIS, an emerging software company in our country. This new system will provide complete support to display, store and analyze mammographic studies in digital format.