Home About us Contact
|
Home About us Contact | ||
|
|
||
Useful Methods (useful + methods)
Selected AbstractsReactive chemicals emergency response and post-event calorimetric testingPROCESS SAFETY PROGRESS, Issue 1 2010David Frurip Abstract A serious upset in process conditions may result in a Reactive Chemicals incident. In such an emergency, procedures must be implemented to prevent injuries, mitigate the event and minimize property loss and/or environmental release as dictated by the required facility Emergency Plan. This article describes the process the Dow Chemical Company uses for engaging Reactive Chemicals experts in an emergency situation. In order to be effective, the Reactive Chemicals expert must have or be provided with in-depth knowledge of the process streams and raw materials involved. The information is crucial for understanding what is happening, what might happen in the immediate future, and what can be done to successfully mitigate the Reactive Chemicals incident. Following the incident, calorimetric experiments are typically performed to confirm or refute the hypotheses of what caused the event; additionally, the experiments provide information as to reactive chemicals hazards that may potentially still exist in the process streams. The aforementioned process will be illustrated by describing an actual event. Useful methods are described and recommended for (a) characterizing and storing reactive chemicals, and (b) responding and mitigating safety incidents with reactive chemicals. The role of a reactive chemicals "expert" during and after a plant emergency is important and potentially critical to the safe handling of an ongoing event and also in determining the root cause of the incident. © 2009 American Institute of Chemical Engineers Process Saf Prog, 2010 [source] Serotonergic dysregulation in bipolar disorders: a literature review of serotonergic challenge studiesBIPOLAR DISORDERS, Issue 6 2002S Sobczak Objectives:, Serotonin (5-hydroxytryptamine; 5-HT) and endocrine abnormalities have been repeatedly reported in bipolar disorders (BD). Useful methods to investigate 5-HT responsivity, and the interaction with neuroendocrine functioning, are provided by acute 5-HT challenge and depletion paradigms. In this review 5-HT challenges are limited to paradigms that stimulate 5-HT activity in BD. Methods:, Literature was searched for in electronic libraries: MEDLINE and PSYCHLIT, period 1966,2001. Papers describing effects of an acute 5-HT challenge on neuroendocrine functioning in BD patients were selected. Results:, Review of the literature revealed 15 studies: five papers described the effects of 5-HT challenges in manic BD patients, four papers in euthymic BD and seven in depressed BD patients. The reviewed 5-HT challenge paradigms are acute administration of oral and intravenous (i.v.) dosage of d,l-fenfluramine, tryptophan, 5-hydroxytryptophan, ipsapirone and buspirone. There were no papers which investigated neuroendocrine effects of m-chlorophenylpiperazine, clomipramine and citalopram in BD patients and were therefore not reviewed. Conclusions:, The literature on 5-HT challenge procedures in BD shows evidence for a blunted prolactin (PRL) in mania and depression as well as a blunted cortisol in euthymic BD patients. This suggests that in both mania and depression similar changes in the 5-HT system are involved. It is speculated that blunting of cortisol responses in euthymic BD patients may be a result of chronically altered 5-HT functioning, whereas changes in PRL release following 5-HT challenges reflect more state-dependent changes in 5-HT activity. The 5-HT responsivity in BD patients has also been associated with pharmacological treatment, suicidal behaviour, weight loss and age. Recommendations for future research are given. [source] Diagnosis of ophthalmic tumoursACTA OPHTHALMOLOGICA, Issue 2009T KIVELÄ Purpose To summarise clinical methods used to diagnose ophthalmic tumours. Methods Personal experience of the author as a member of the European Ophthalmic Oncology Group. Results Conjunctival tumours are excised based on provisional clinical diagnosis or, if they are extensive, atypical or part of systemic disease such as lymphoma, first biopsied to obtain a histopathologic diagnosis. Useful methods to diagnose and stage conjunctival tumours are high frequency ultrasonography (US) or ultrasound biomicroscopy (UBM) to measure their thickness, in vivo confocal microscopy or impression cytology to chart their extent, and exfoliative cytology to get a provisional diagnosis. Ciliary body tumours are visualised by radical biomicroscopy, transillumination and indirect ophthalmoscopy with scleral indentation, supplemented with high frequency US or UBM. Binocular indirect ophthalmoscopy and US form the basis or diagnosing choroidal tumours. In addition to fluorescein and indocyanine green angiography in atypical cases, optical coherence tomography to detect subretinal fluid and autofluorescence to detect orange pigment are useful adjuncts in telling a small melanoma from a naevus. The mnemonic "To Find Small Ocular Melanomas" (from Thickness >2mm, subretinal Fluid, Symptoms, Orange pigment, Margin touching disc) is also useful in this respect. Clinical diagnosis of medium-sized to large melanomas is 99% accurate, whereas a fine needle or vitrectomy biopsy may be necessary to diagnose atypical tumours and is also used for cytogenetic analysis of uveal melanomas. Conclusion Conjunctival tumours are mostly diagnosed histopathologically, whereas diagnosis of uveal tumours is usually based on clinical examination. While clinical diagnosis is usually reliable, biopsy of uveal tumours is increasingly used for prognostic purposes. [source] Stability and accuracy analysis of a discrete model reference adaptive controller without and with time delayINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 9 2010Oreste S. Bursi Abstract Adaptive control techniques can be applied to dynamical systems whose parameters are unknown. We propose a technique based on control and numerical analysis approaches to the study of the stability and accuracy of adaptive control algorithms affected by time delay. In particular, we consider the adaptive minimal control synthesis (MCS) algorithm applied to linear time-invariant plants, due to which, the whole controlled system generated from state and control equations discretized by the zero-order-hold (ZOH) sampling is nonlinear. Hence, we propose two linearization procedures for it: the first is via what we term as physical insight and the second is via Taylor series expansion. The physical insight scheme results in useful methods for a priori selection of the controller parameters and of the discrete-time step. As there is an inherent sampling delay in the process, a fixed one-step delay in the discrete-time MCS controller is introduced. This results in a reduction of both the absolute stability regions and the controller performance. Owing to the shortcomings of ZOH sampling in coping with high-frequency disturbances, a linearly implicit L-stable integrator is also used within a two degree-of-freedom controlled system. The effectiveness of the methodology is confirmed both by simulations and by experimental tests. Copyright © 2009 John Wiley & Sons, Ltd. [source] Relational mountain (density) clustering method and web log analysisINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 3 2005Kuhu Pal The mountain clustering method and the subtractive clustering method are useful methods for finding cluster centers based on local density in object data. These methods have been extended to shell clustering. In this article, we propose a relational mountain clustering method (RMCM), which produces a set of (proto) typical objects as well as a crisp partition of the objects generating the relation, using a new concept that we call relational density. We exemplify RMCM by clustering several relational data sets that come from object data. Finally, RMCM is applied to web log analysis, where it produces useful user profiles from web log data. © 2005 Wiley Periodicals, Inc. Int J Int Syst 20: 375,392, 2005. [source] Primary Pulmonary Artery Sarcoma: Surgical Management and Differential Diagnosis with Pulmonary Embolism and Pulmonary Valve StenosisJOURNAL OF CARDIAC SURGERY, Issue 6 2009Xiao-Peng Hu M.D. We present six cases of primary pulmonary artery sarcomas and discuss clinical features, differential diagnosis, surgical treatment, and outcome of the tumors. Methods: Between January 1994 and July 2008, six patients were identified with the disease during operation. Three patients were initially diagnosed with pulmonary valve stenosis, and two patients had a presumptive diagnosis of chronic pulmonary embolism. Two patients had simple or partial tumor resection. Four patients had radical tumor resection and homograft reconstruction of the pulmonary arteries. Results: Histological examinations showed five malignant mesenchymomas and one fibrosarcoma. One patient died of refractory pulmonary hypertension during operation. Two patients died 4 months postoperatively because of brain metastases. Two patients were alive for 3 and 9 months, respectively after the operation with recurrent tumor. One patient is alive even 2 years after resection with no signs of recurrence or metastasis. Conclusions: Because of similar clinical features, pulmonary artery sarcomas are often confused with other pulmonary vascular obstructive diseases. Computed tomography scanning and gadolinium-enhanced magnetic resonance imaging could be useful methods for differential diagnosis. The prognosis is very poor. The survival time after resection varies from several months to several years depending on the presence of recurrence or metastasis. Early diagnosis and radical surgical resection presents the only opportunity for a potential cure. [source] Self-evaluation and peer review , an example of action research in promoting self-determination of patients with rheumatoid arthritisJOURNAL OF CLINICAL NURSING, Issue 3a 2007LicNSc, Päivi Löfman RN Aims and objectives., The aim of this paper was to describe the areas that have been performed well and the areas in need of further development of rheumatoid arthritis patients. Background., Nurses' self-evaluation and peer review are important methods for ascertaining the changes and success in the development of nursing practice. To date, there has been minimal research regarding the use of those evaluation methods in nursing practice. Design., The findings of self-evaluation and peer review of nurses are described in a participatory action research study aimed at promotion of self-determination for patients with rheumatoid arthritis. Methods., In self-evaluation, the collection of data was accomplished using a self-evaluation instrument with the permanent nursing staff (n = 18), then analysed through quantitative methods. For peer review, the data were gathered through focus groups (n = 21) using a tool similar to the one used for self-evaluation. The participants included many of the same nurses as in self-evaluation. The data were analysed using qualitative content analysis. Results., Well-performed areas in nursing of rheumatoid arthritis patients were found to be promoting patient participation, supporting self-determination, performing patient-centred nursing and raising patient self-respect. The areas in need of development were connected to the nursing staff themselves: increasing collaboration of nursing staff, decreasing authoritarianism in nursing care and developing nursing practice with colleagues. Conclusions., Self-evaluation and peer review are complementary and support one another, especially since nurses were found to be more critical in their self-evaluations than in peer review. Relevance to clinical practice., Both evaluation tools proved to be useful methods in the evaluation phase of the action research process as a means of professional development. Also assisting in the development of clinical nursing practice. [source] On the neglecting of higher-order cumulants in EXAFS data analysisJOURNAL OF SYNCHROTRON RADIATION, Issue 6 2009A. Sanson The cumulant expansion is one of the most powerful and useful methods for EXAFS data analysis, in which the higher-order cumulants allow to consider deviations from a simple Gaussian distribution. In this work, analytical expressions have been derived to show the effects of neglecting higher-order cumulants in EXAFS analysis by the ratio method. The errors in the best-fitting procedure owing to the omission of the higher-order cumulants, as well as of the coordination number, can be determined. [source] Liposome/water lipophilicity: Methods, information content, and pharmaceutical applicationsMEDICINAL RESEARCH REVIEWS, Issue 3 2004Georgette Plemper van Balen Abstract This review discusses liposome/water lipophilicity in terms of the structure of liposomes, experimental methods, and information content. In a first part, the structural properties of the hydrophobic core and polar surface of liposomes are examined in the light of potential interactions with solute molecules. Particular emphasis is placed on the physicochemical properties of polar headgroups of lipids in liposomes. A second part is dedicated to three useful methods to study liposome/water partitioning, namely potentiometry, equilibrium dialysis, and 1H-NMR relaxation rates. In each case, the principle and limitations of the method are discussed. The next part presents the structural information encoded in liposome/water lipophilicity, in other words the solutes' structural and physicochemical properties that determine their behavior and hence their partitioning in such systems. This presentation is based on a comparison between isotropic (i.e., solvent/water) and anisotropic (e.g., liposome/water) systems. An important factor to be considered is whether the anisotropic lipid phase is ionized or not. Three examples taken from the authors' laboratories are discussed to illustrate the factors or combinations thereof that govern liposome/water lipophilicity, namely (a) hydrophobic interactions alone, (b) hydrophobic and polar interactions, and (c) conformational effects plus hydrophobic and ionic interactions. The next part presents two studies taken from the field of QSAR to exemplify the use of liposome/water lipophilicity in structure,disposition and structure,activity relationships. In the conclusion, we summarize the interests and limitations of this technology and point to promising developments. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 3, 299,324, 2004 [source] The clinical significance of food specific IgE/IgG4 in food specific atopic dermatitisPEDIATRIC ALLERGY AND IMMUNOLOGY, Issue 1 2007Geunwoong Noh Food is closely associated with the pathogenesis of atopic dermatitis. Food allergy is usually mediated by IgE antibody to specific food proteins and determination of specific IgE antibody is the basis of the common diagnostic test for food allergy. IgG4 have been reported as blocking antibody and the protective effects of blocking antibody may be clear in inhalant allergy. However, the role of IgG4 in food allergy is still a matter of debate. In this study, the clinical significance of food allergen-specific IgE/IgG4 in atopic dermatitis was investigated and compared with that of IgE. A total of 97 patients who fulfilled the diagnostic criteria for atopic dermatitis participated in this study. Skin prick test and allergy patch test were performed. Specific IgE and IgG4 concentration were measured using allergy protein chip, ,AllergyChip'. Double blinded placebo controlled food challenge test (DBPCFC) was performed for the diagnosis of allergy to milk, egg white, wheat, and soybean. DBPCFCs for milk, egg white, soybean, and wheat were performed. The positive rates were 31.7% (19/60) in milk, 36.7% (18/49) in egg white, 30.4% (7/23) in soybean, and 34.8% (8/23) in wheat. Mean IgE/IgG4 levels in DBPCFC (+) subjects is higher than those in DBPCFC (,) subjects in all food items studied. Of them, there were significantly different between two groups in egg white and wheat (Egg white in DBPCFC (+) vs. (,): 0.4 ± 0.3 vs. 0.2 ± 0.2, wheat in DBPCFC (+) vs. (,): 1.2 ± 1.2 vs. 0.3 ± 0.3, p < 0.05). Allergen-specific IgE/IgG4 may provide one of the clues to understand the mechanism of food allergy in atopic dermatitis. The present study suggests that protein microarray can be one of the useful methods to assess ongoing status of allergic diseases. [source] How do helix,helix interactions help determine the folds of membrane proteins?PROTEIN SCIENCE, Issue 4 2003Perspectives from the study of homo-oligomeric helical bundles FRET, fluorescence resonance energy transfer; NBD, 7-nitrobenz-2-oxa-1,3-diazole; C-14 betaine, N -tetradecyl- N,N -dimethyl-3-ammonio-1-propanesulfonate; MF, mole fraction Abstract The final, structure-determining step in the folding of membrane proteins involves the coalescence of preformed transmembrane helices to form the native tertiary structure. Here, we review recent studies on small peptide and protein systems that are providing quantitative data on the interactions that drive this process. Gel electrophoresis, analytical ultracentrifugation, and fluorescence resonance energy transfer (FRET) are useful methods for examining the assembly of homo-oligomeric transmembrane helical proteins. These methods have been used to study the assembly of the M2 proton channel from influenza A virus, glycophorin, phospholamban, and several designed membrane proteins,all of which have a single transmembrane helix that is sufficient for association into a transmembrane helical bundle. These systems are being studied to determine the relative thermodynamic contributions of van der Waals interactions, conformational entropy, and polar interactions in the stabilization of membrane proteins. Although the database of thermodynamic information is not yet large, a few generalities are beginning to emerge concerning the energetic differences between membrane and water-soluble proteins: the packing of apolar side chains in the interior of helical membrane proteins plays a smaller, but nevertheless significant, role in stabilizing their structure. Polar, hydrogen-bonded interactions occur less frequently, but, nevertheless, they often provide a strong driving force for folding helix,helix pairs in membrane proteins. These studies are laying the groundwork for the design of sequence motifs that dictate the association of membrane helices. [source] Fault isolation in nonlinear systems with structured partial principal component analysis and clustering analysisTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2000Yunbing Huang Abstract Partial principal component analysis (PCA) and parity relations are proven to be useful methods in fault isolation. To overcome the limitation of applying partial PCA to nonlinear problems, a new approach utilizing clustering analysis is proposed. By dividing a partial data set into smaller subsets, one can build more accurate PCA models with fewer principal components, and isolate faults with higher precision. Simulations on a 2 × 2 nonlinear system and the Tennessee Eastman (TE) process show the advantages of using the clustered partial PCA method over other nonlinear approaches. L'analyse des principaux constituants partielle et les relations de parité s'avèrent des méthodes utiles pour isoler les défaillances. Mais étant donné les limites d'application de l'analyse partielle des principaux constituants, on propose une nouvelle méthode reposant sur l'analyse de la formation des grappes. En divisant un jeu de données partielles en plusieurs sous-groupes plus petits, on peut créer des modèles d'analyse des principaux constituants plus précis avec un nombre de constituants moins importants et isoler les défaillances avec une meilleure précision. Les simulations sur un système non linéaire 2 × 2 et le procédé Tennessee Eastman (TE) montrent les avantages de la méthode d'analyse des principaux constituants partielle par grappes par rapport aux autres methodes non linéaires. [source] | |||||||||||||