A GC–MS-based metabonomic investigation of blood serum from irritable bowel syndrome patients undergoing intervention with acidified milk products

In the present study, the use of gas chromatography mass spectrometry (GC–MS)-based metabonomics to characterize blood serum in an intervention study of patients suffering from the common gastrointestinal disorder irritable bowel syndrome (IBS) was investigated. The patients included in the study consumed an acidified milk product with (n = 30) or without probiotics (n = 31) (Lactobacillus paracasei F19, Lactobacillus acidophilus LA-5 and Bifidobacterium lactis BB-12) for an 8-week period, and blood serum samples were collected before and after the intervention. Acidified milk is commonly used as a delivering vector for probiotics in commercial consumer settings. The serum samples were extracted and derivatized using N-Methyl-N-(trimethylsilyl) trifluoroacetamide (MSTFA), and GC–MS analysis was carried out. Multivariate data analysis including principal component analysis (PCA), orthogonal partial least squares-discriminant analysis (OPLS-DA), and S-plot was applied on the obtained GC–MS data, which revealed higher serum lactate, glutamine, proline creatinine/creatine, and aspartic acid levels and lower serum glucose levels after the intervention period for both treatment groups. Consequently, the present study indicated an effect of acidified milk consumption on the plasma metabolite profile, which was independent of a concomitant intake of probiotics. In addition, the present study demonstrates that GC–MS is a useful analytical technique for metabonomics studies of blood serum.     

Fault handling for a wind farm with an internal DC collection grid

As a result of the increased wind power penetration, there are increased requirements for robustness of the wind farms during disturbances and faults. The wind farms are required to stay connected during short grid faults, and also, the disturbances as a result of internal faults should be minimized. In this paper, the fault ride‐through properties during external faults for a wind farm with an internal direct current (DC) grid are investigated. A safe detection of the fault is derived, as well as the reconnection procedure after the fault has been cleared. Also, the operation during internal faults has been investigated, focusing on the faults in the DC bus. It has been shown that the wind farm with an internal DC grid can operate through faults in the external grid and reconnect well within the requirements stated in the grid codes. Further, methods for detection of internal faults are derived, and it was shown that a faulted part can be disconnected and the non‐faulted parts can be back in operation within 100 ms using a DC breaker in each radial and within 300 ms without DC breakers. Copyright © 2011 John Wiley & Sons, Ltd.     

Students' conceptions of matter.

The aim of this study was to reveal how upper level compulsory school students (13 to 16 years old) conceptualize matter. Twenty individually administered interviews were carried out, transcribed word for word and analyzed in accordance with the phenomenographic approach adopted. Six distinctively different conceptions were found. Matter can be understood as (a) homogeneous substance, (b) substance units, (c) substance units with "small atoms," (d) aggregate of particles, (e) particle units, or (f) systems of particles. Differences in focus constitute a variation in the internal structure of each conception. There are also alternative forms of the same conception in some cases. The different conceptions, their varying internal structures, and the alternative forms of conceptions found are logically interrelated in a system, called the "outcome space," which depicts how thinking about matter may vary qualitatively between and within students. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Direct and indirect model reference adaptive control

The paper considers the control of an unknown linear time-invariant plant using Direct and Indirect Model Reference Adaptive Control. Employing a specific controller structure and the concept of positive realness, adaptive laws are derived using Indirect Control which are identical to those obtained in the case of Direct Control. The stability questions that arise are also shown to be the same. Simulation results using the new scheme are presented for the control of both stable and unstable plants.     

A study of sulfur bridges in filled natural rubber vulcanizates by pyrolysis gas chromatography with flame-photometric detection

Natural rubber vulcanizates of two formulations, with sulfur/N-cyclohexyl-2-benzothiazolesulfenamide (CBS) and tetramethylthiuram disulfide (TMTD), respectively, were analyzed by pyrolysis gas chromatography. A sulfur-selective flame-photometric detector was utilized. The main pyrolysis products were identified as CS₂ and some thiophenes. The yields of the pyrolysis products from the two types of rubber were very different. The yields also varied with the curing time of the rubbers.     

Antibacterial activity of fullerene water suspensions (nC60) is not due to ROS-mediated damage

The cytotoxic and antibacterial properties of nC 60, a buckminsterfullerene water suspension, have been attributed to photocatalytically generated reactive oxygen species (ROS). However, in this work, neither ROS production nor ROS-mediated damage is found in nC 60-exposed bacteria. Furthermore, the colorimetric methods used to evaluate ROS production and damage are confounded by interactions between nC 60 and the reagents, yielding false positives. Instead, we propose that nC 60 exerts ROS-independent oxidative stress, thus reconciling conflicting results in the literature.     

Field assessment of lead immobilization in a contaminated soil after phosphate application

A pilot-scale field demonstration was conducted at a Pb-contaminated site to assess the effectiveness of Pb immobilization using P amendments. The test site was contaminated by past battery recycling activities, with average soil Pb concentration of 1.16%. Phosphate amendments were applied at a 4.0 molar ratio of P/Pb with three treatments: T1, 100% P from H(3)PO(4); T2, 50% from H(3)PO(4)+50% from Ca(H(2)PO(4))(2); and T3, 50% from H(3)PO(4)+5% phosphate rock. Soil samples were collected and characterized 220 days after P application. Surface soil pH was reduced from 6.45 to 5.05 in T1, to 5.22 in T2, and to 5.71 in T3. Phosphate treatments effectively transformed up to 60% of total soil Pb from the non-residual fraction (sum of water soluble and exchangeable, carbonate, Fe-Mn oxide, and organic fractions) to the residual fraction relative to the control. In addition, P treatments reduced Toxicity Characteristic Leaching Procedure (TCLP) Pb from 82 mg l(-1) to below EPA's regulatory level of 5 mg l(-1) in the surface soil. Scanning electron microscopy-energy dispersive X-ray elemental analysis and X-ray diffraction analysis indicated formation of insoluble chloropyromorphite [Pb(5)(PO(4))(3)Cl] mineral in the P-treated soils. Although H(3)PO(4) is necessary to dissolve meta-stable Pb in soil for further lead immobilization, it should be used with caution due to its potential secondary contamination. A mixture of H(3)PO(4) and Ca(H(2)PO(4))(2) or phosphate rock was effective in immobilizing Pb with minimum adverse impacts associated with pH reduction.     

Salivary theophylline estimation in the management of asthma in children

Simultaneous sampling was performed to determine whether saliva could replace plasma in the monitoring of theophylline dosages. Forty-eight children with moderate to severe asthma received oral theophylline preparation (usually sustained release) on a daily basis. They provided simultaneous saliva and plasma samples at routine out-patient visits. Saliva and plasma theophylline concentrations showed a wide variation between individuals, and their ratios also differed. Saliva theophylline concentrations below 7 micrograms/ml reflect plasma concentrations below 10 micrograms/ml, i.e. sub-therapeutic, while saliva concentrations above 7 micrograms/ml are consistent with therapeutic dosage. Estimation of saliva theophylline concentration on routine visits avoids the discomfort of blood sampling. It reflects whether daily oral theophylline dosage in childhood asthma is below or within the therapeutic range. The need for changes in dosage and the degree of patient-compliance with therapy can be usefully indicated.     

Burden of self-care in seriously ill patients: Impact on adjustment.

Perceived, but not actual, control over treatment has been consistently related to better adjustment in chronic illness. This study examined the relationship between actual control over treatment and severity of illness and their influence on depression in a chronically ill population of end-stage renal disease (ESRD) patients. The authors hypothesized that as severity of illness increases, the burden of control over treatment would increase depression. Severity of illness and depression was assessed for 98 ESRD patients. Control over treatment was represented by whether dialysis patients were self-administering treatment (high control) or were receiving treatment from the medical staff (low control). Results indicated that for the most severely ill patients, high control over treatment resulted in poorer adjustment. Furthermore, this effect was due in part to how illness interferes with social relationships in seriously ill, self-care patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Esistenza e stabilità degli stati di equilibrio degli schemi Runge-Kutta

In this paper we investigate the boundaries of applicability of the theory of the equilibrium states of Runge-Kutta schemes developed in [1], [2].

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Lavoro svolto nell’ambito del Centro interuniversitario di Analisi Numerica e Matematica Computazionale. Classificazione AMS 65L05.