Transition region ignition characteristics of n-heptane fuel sprays

Ignition studies were perferred on monodisperse n-heptane sprays at atmospheric pressure over a range of equivalence ratios and droplet diameters. A capacitive discharge spark ignition system was used as the ignition source, providing independent control of spark energy and duration. Preliminary measurements were made to optimize spark duration and spark gap, optimum conditions being those at which the maximum frequency or probability of ignition was observed. The effect of spark duration on ignition frequency for several spark energies was determined for equivalence ratios of 0.5 and 1.0 and initial droplet diameters of 28 and 68 microns. Spark duration had little effect on ignition frequency over the entire 15 to 170 mu s range examined. Spark durations of 70 to 80 mu s were used for all subsequent work. The spark gap was optimized at equivalence ratios of 0.6, 0.8 and 1.0 and initial droplet diameters of 30, 40, 50, 60 and 70 microns by varying the electrode spacing from 0.5 to 5.0 mm while maintaining a constant spark energy. The optimum gap was determined to be 3.0 mm for nearly all conditions

Combustion characteristics in the transition region of liquid fuel sprays

A number of important effects were observed in the droplet size transition region in spray combustion systems. In this region, where the mechanism of flame propagation is transformed from diffusive to premixed dominated combustion, the following effects have been observed: (1) maxima in burning velocity; (2) extension of flammability limits; (3) minima in ignition energy; and (4) minima in NO(x) formation. Unfortunately, because of differences in experimental facilities and limitations in the ranges of experimental data, a unified description of these transition region effects is not available at this time. Consequently, a fundamental experimental investigation was initiated to study the effect of droplet size, size distribution, and operating parameters on these transition region phenomena in a single well controlled spray combustion facility

Combustion characteristics in the transition region of liquid fuel sprays

A number of important effects have been observed in the droplet size transition region in spray combustion systems. In this region, where the mechanism of flame propagation is transformed from diffusive to premixed dominated combustion, the following effects have been observed: (1) maxima in burning velocity; (2) extension of flammability limits; (3) minima in ignition energy; and (4) minima in NOx formation. A monodisperse aerosol generator has been used to form and deliver a well controlled liquid fuel spray to the combustion test section where measurements of ignition energy have been made. The ignition studies were performed on monodisperse n-heptane sprays at atmospheric pressure over a range of equivalence ratios and droplet diameters. A capacitive discharge spark ignition system was used as the ignition source, providing independent control of spark energy and duration. Preliminary measurements were made to optimize spark duration and spark gap, optimum conditions being those at which the maximum frequency or probability of ignition was observed. Using the optimum electrode spacing and spark duration, the frequency of ignition was determined as a function of spark energy for three overall equivalence ratios (0.6, 0.8, and 1.0) and for initial droplet diameters of 25, 40, 50, 60, and 70 micro m

Robust similarity metrics for the registration of 3D multimodal medical images

In this paper, we develop data driven registration algorithms, relying on pixel similarity metrics, that enable an accurate rigid registration of dissimilar single or multimodal 2D/3D medical images . Gross dissimilarities are handled by considering similarity measures related to robust M-estimators . Fast stochastic multigrid optimization algorithms are used to minimize these similarity metrics . The proposed robust similarity metrics are compared to the most popular standard similarity metrics on real MRI/MRI and MRI/SPECT image pairs showing gross dissimilarities . A blinded evaluation of the algorithm was performed, using as gold standard a prospective, marker-based registration method, by participating in a registration evaluation project (Vanderbilt University) . Our robust similarity measures compare favourably with all standard (non robust) techniques .Le recalage non supervisé d'images médicales volumiques reste un problème difficile en raison de l'importante variabilité et des grandes différences d'information pouvant apparaître dans des séquences d'images de même modalité ou dans des couples d'images multimodales. Nous présentons dans cet article des méthodes robustes de recalage rigide d'images 2D et 3D monomodales et multimodales, reposant sur la minimisation de mesures de similarité inter-images. Les méthodes proposées s'appuient sur la théorie de l'estimation robuste et mettent en oeuvre des M-estimateurs associés à des techniques d'optimisation stochastique multigrilles rapides. Ces estimateurs robustes sont évalués à travers le recalage d'images médicales volumiques monomodales (IRM/IRM) et multimodales (IRM/TEMP). Ils sont comparés aux autres fonctions de similarité classiques, proposées dans la littérature. Les méthodes de recalage robustes ont, en particulier, été validées dans le cadre d'un protocole comparatif mis en place par l'Université de Vanderbilt. Elles sont actuellement utilisées en routine clinique et conduisent, tant pour les images de même modalité que pour les images multimodales à une précision sous-voxel, comparable aux meilleures méthodes actuelles. Elles permettent de plus de recaler des couples d'images sur lesquels les méthodes classiques échouent

Metabolomic Characterization of Ovarian Epithelial Carcinomas by HRMAS-NMR Spectroscopy

Objectives. The objectives of the present study are to determine if a metabolomic study by HRMAS-NMR can (i) discriminate between different histological types of epithelial ovarian carcinomas and healthy ovarian tissue, (ii) generate statistical models capable of classifying borderline tumors and (iii) establish a potential relationship with patient's survival or response to chemotherapy. Methods. 36 human epithelial ovarian tumor biopsies and 3 healthy ovarian tissues were studied using 1H HRMAS NMR spectroscopy and multivariate statistical analysis. Results. The results presented in this study demonstrate that the three histological types of epithelial ovarian carcinomas present an effective metabolic pattern difference. Furthermore, a metabolic signature specific of serous (N-acetyl-aspartate) and mucinous (N-acetyl-lysine) carcinomas was found. The statistical models generated in this study are able to predict borderline tumors characterized by an intermediate metabolic pattern similar to the normal ovarian tissue. Finally and importantly, the statistical model of serous carcinomas provided good predictions of both patient's survival rates and the patient's response to chemotherapy. Conclusions. Despite the small number of samples used in this study, the results indicate that metabolomic analysis of intact tissues by HRMAS-NMR is a promising technique which might be applicable to the therapeutic management of patients

A phase II study in advanced breast cancer: ZD1694 ('Tomudex') a novel direct and specific thymidylate synthase inhibitor.

ZD1694 ('Tomudex'), a novel, direct and specific thymidylate synthase (TS) inhibitor, was developed in a collaborative research programme between Zeneca Pharmaceuticals and the Institute of Cancer Research (UK) and entered clinical trials in 1991; phase II studies began in 1992, using 3.0 mg m-2 every 3 weeks as a short 15 min infusion. Forty-six patients entered a phase II study of ZD1694 in advanced breast cancer. A total of 74% of patients had received prior systemic therapy (either as adjuvant cytotoxic or hormonal therapy or hormone therapy for advanced disease); 39% had received prior adjuvant cytotoxic chemotherapy. All patients had measurable disease and 50% had liver metastases. In all 43 patients were evaluable for response. Of these patients 26% achieved complete (CR) or partial response (PR) (95% Cl 14-42%). A response rate of 44% was seen in liver metastases. Two patients achieved CR of 265 and 301 days' duration respectively, one in locoregional disease, and one in liver metastases. The most common grade 3/4 adverse events were nausea and vomiting (11%), diarrhoea (11%) and leucopenia (20%). Grade 3/4, self-limited and reversible increases in transaminases were seen in 22% of patients. ZD1694 has useful single agent activity in patients with hormone-refractory advanced breast cancer, comparable with that reported for other anti-metabolites, with acceptable tolerability

Application of an original RT-PCR–ELISA multiplex assay for MDR1 and MRP, along with p53 determination in node-positive breast cancer patients

The long-term prognostic value of tumoural MDR1 and MRP, along with p53 and other classical parameters, was analysed on 85 node-positive breast cancer patients receiving anthracycline-based adjuvant therapy. All patients underwent tumour resection plus irradiation and adjuvant chemotherapy (the majority receiving fluorouracil–epirubicin–cyclophosphamide). Median follow-up for the 54 alive patients was 7.8 years. Mean age was 53.7 years (range 28–79) and 54 patients were post-menopausal. MDR1 and MRP expression were quantified according to an original reverse transcription polymerase chain reaction multiplex assay with colourimetric enzyme-linked immunosorbent assay detection(β2-microglobulin as control). P53 protein was analysed using an immunoluminometric assay (Sangtec). MDR1 expression varied within an 11-fold range (mean 94, median 83), MRP within a 45-fold range (mean 315, median 242) and p53 protein from the limit of detection (0.002 ng mg−1) up to 35.71 ng mg−1(mean 1.18, median 0.13 ng mg−1). P53 protein was significantly higher in oestrogen receptor (ER)-negative than in ER-positive tumours (P = 0.039). The higher the p53, the lower the MDR1 expression (P = 0.015, r = –0.27). P53 was not linked to progesterone receptor (PR) status, S phase fraction, or MRP. Significantly greater MDR1 expression was observed in grade I tumours (P = 0.029). No relationship was observed between MDR1 and MRP. Neither MDR1 nor MRP was linked to ER or PR status. Unlike MDR1, MRP was correlated with the S phase: the greater the MRP, the lower the S phase (P = 0.006, r = –0.42). Univariate Cox analyses revealed that MDR1, MRP, p53 and S phase had no significant influence on progression-free or specific survival. A tendency suggested that the greater the p53, the shorter the progression-free survival (P = 0.076 as continuous and 0.069 as dichotomous). © 2000 Cancer Research Campaig

High-resolution magic angle spinning 1H nuclear magnetic resonance spectroscopy metabolomics of hyperfunctioning parathyroid glands

Background Primary hyperparathyroidism (PHPT) may be related to a single gland disease or multiglandular disease, which requires specific treatments. At present, an operation is the only curative treatment for PHPT. Currently, there are no biomarkers available to identify these 2 entities (single vs. multiple gland disease). The aims of the present study were to compare (1) the tissue metabolomics profiles between PHPT and renal hyperparathyroidism (secondary and tertiary) and (2) single gland disease with multiglandular disease in PHPT using metabolomics analysis. Methods The method used was 1H high-resolution magic angle spinning nuclear magnetic resonance spectroscopy. Forty-three samples from 32 patients suffering from hyperparathyroidism were included in this study. Results Significant differences in the metabolomics profile were assessed according to PHPT and renal hyperparathyroidism. A bicomponent orthogonal partial least square-discriminant analysis showed a clear distinction between PHPT and renal hyperparathyroidism (R2Y = 0.85, Q2 = 0.63). Interestingly, the model also distinguished single gland disease from multiglandular disease (R2Y = 0.96, Q2 = 0.55). A network analysis was also performed using the Algorithm to Determine Expected Metabolite Level Alterations Using Mutual Information (ADEMA). Single gland disease was accurately predicted by ADEMA and was associated with higher levels of phosphorylcholine, choline, glycerophosphocholine, fumarate, succinate, lactate, glucose, glutamine, and ascorbate compared with multiglandular disease. Conclusion This study shows for the first time that 1H high-resolution magic angle spinning nuclear magnetic resonance spectroscopy is a reliable and fast technique to distinguish single gland disease from multiglandular disease in patients with PHPT. The potential use of this method as an intraoperative tool requires specific further studies. © 2016 Elsevier Inc

A new specific succinate-glutamate metabolomic hallmark in SDHx-related paragangliomas

Paragangliomas (PGLs) are frequently associated with germline mutations in genes involved in energy metabolism. The purpose of the present study was to assess whether the tumor metabolomic profile of patients with hereditary and apparently sporadic PGLs enables the distinction of different subtypes of tumors. Twenty-eight unrelated patients with a histological diagnosis of PGLs were included in the present study. Twelve had germline mutations in SDHx genes (5 SDHB, 7 SDHD), 6 VHL, and 10 were apparently sporadic. Intact tumor samples from these patients (one per patient) were evaluated with (1)H high-resolution magic angle spinning (HRMAS) NMR spectroscopy. SDHx-related tumors were characterized by an increase in succinate levels in comparison to other tumor subtypes (p = 0.0001 vs VHL and p = 0.000003 vs apparently sporadic). Furthermore, we found significantly lower values of glutamate in SDHx-related tumors compared to other subtypes (p = 0.0007 vs VHL and p = 0.003 vs apparently sporadic). Moreover, SDHx-tumors also exhibited lower values of ATP/ADP/AMP (p = 0.01) compared to VHL. VHL tumors were found to have the highest values of glutathione (GSH) compared to other tumors. Based on 4 metabolites (succinate, glutamate, GSH, and ATP/ADP/AMP), tumors were accurately distinguished from the other ones on both 3- and 2-class PLS-DA models. The present study shows that HRMAS NMR spectroscopy is a very promising method for investigating the metabolomic profile of various PGLs. The present data suggest the existence of a specific succinate-glutamate hallmark of SDHx PGLs. The relevance of such a metabolomic hallmark is expected to be very useful in designing novel treatment options as well as improving the diagnosis and follow-up of these tumors, including metastatic ones