Chemical Cleaning of Oil Refinery Heat Exchangers -- The Need for a Joint Effort

One component of the high cost of fouling to oil refineries is the maintenance money spent to clean fouled heat exchangers and the associated lost production while the exchanger is out of service. This presentation will highlight some specific fouling situations in oil refineries which can benefit from chemical cleaning. Cooperative efforts are needed between refinery operators, researchers, and chemical suppliers to develop the proper solvents and to find the optimum procedures to use them for cleaning

Grundfos: Chlorination of Swimming Pools

In this report a model is developed for describing the mixing of chemicals in water systems. We construct a three-variable ODE system describing the concentration of chlorine, bacteria, and organic molecules. We show that a pump strategy is effective in regulating the chlorine concentration

New dynamics in cerebellar Purkinje cells: torus canards

We describe a transition from bursting to rapid spiking in a reduced mathematical model of a cerebellar Purkinje cell. We perform a slow-fast analysis of the system and find that -- after a saddle node bifurcation of limit cycles -- the full model dynamics follow temporarily a repelling branch of limit cycles. We propose that the system exhibits a dynamical phenomenon new to realistic, biophysical applications: torus canards.Comment: 4 pages; 4 figures (low resolution); updated following peer-review: language and definitions updated, Figures 1 and 4 updated, typos corrected, references added and remove

Turbulence-induced melting of a nonequilibrium vortex crystal in a forced thin fluid film

To develop an understanding of recent experiments on the turbulence-induced melting of a periodic array of vortices in a thin fluid film, we perform a direct numerical simulation of the two-dimensional Navier-Stokes equations forced such that, at low Reynolds numbers, the steady state of the film is a square lattice of vortices. We find that, as we increase the Reynolds number, this lattice undergoes a series of nonequilibrium phase transitions, first to a crystal with a different reciprocal lattice and then to a sequence of crystals that oscillate in time. Initially the temporal oscillations are periodic; this periodic behaviour becomes more and more complicated, with increasing Reynolds number, until the film enters a spatially disordered nonequilibrium statistical steady that is turbulent. We study this sequence of transitions by using fluid-dynamics measures, such as the Okubo-Weiss parameter that distinguishes between vortical and extensional regions in the flow, ideas from nonlinear dynamics, e.g., \Poincare maps, and theoretical methods that have been developed to study the melting of an equilibrium crystal or the freezing of a liquid and which lead to a natural set of order parameters for the crystalline phases and spatial autocorrelation functions that characterise short- and long-range order in the turbulent and crystalline phases, respectively.Comment: 31 pages, 56 figures, movie files not include

Disease management with home telemonitoring aimed at substitution of usual care in the Netherlands: Post-hoc analyses of the e-Vita HF study

BACKGROUND: Home telemonitoring in heart failure (HF) patients may reduce workload of HF nurses by reducing face-to-face contacts. The aim of this study is to assess whether telemonitoring as a substitution could have negative effects as expressed by less reduction in circulating natriuretic peptide levels between baseline and one-year of follow up compared to usual care. METHODS: A post-hoc analysis of the e-Vita HF trial, a three-arm parallel randomized trial conducted in stable HF patients. Patients were randomized into three arms: (i) usual HF outpatient care, (ii) usual care combined with the use of the website heartfailurematters.org, and (iii) telemonitoring (e-Vita HF platform) instead of face-to-face consultations. Mixed linear model analyses were applied to assess differences in the N-terminal prohormone of brain natriuretic peptide (NT-proBNP) levels between the three arms over a year. RESULTS: A total of 223 participants could be included (mean age 67.1 ± 10.1 years, 27% women, New York Heart Association class I–IV; 39%, 38%, 14%, and 9%). The mean left ventricular ejection fraction was 35 ± 10%. The median of routine face-to-face contacts over a year was 1.0 lower (2.0 vs. 3.0) in the third arm compared with usual care. Median NT-proBNP levels did not significantly differ between the three arms. CONCLUSION: In stable and optimally treated HF patients, telemonitoring causing a reduction of routine face-to-face contacts seems not to negatively affect hemodynamic status as measured by NT-proBNP levels over time

Antibiotic reduction on farms in the United Kingdom, as a result of the introduction of PCV2 vaccination in piglets

Porcine Circovirus Disease (PCVD) was first described in the UK in 1997\u27. Since 1999 it has been a major cause of mortality in the pig industry and has been estimated to cost the British pig industry £30M per year (2004)2 The introduction of PCV2 vaccines has allowed greater control of PCVD, a significant reduction in mortality and an improvement in production parameters in herds throughout the UK3 Sporadic Porcine Dermatitis and Nephropathy Syndrome (PDNS) has been observed as an early indicator of PCVD on some farms and may also be a reflection of post-PMWS in the British national herd. This study looks at the improvement in mortality, performance and the reduction in antibiotics in pigs sourced from a 900 sow unit in East Anglia, England, (Farm A) following the introduction of lngelvac CircoFLEX®. \u27Farm A\u27 is one of 28 breeding units belonging to a large commercial pig business (comprising 26,000 sows in total). This study also analyses the reduction in overall medication costs for all the pigs reared in this company in 2007 compared to 2008, following the introduction of lngelvac CircoFLEX®

Acrophyseal growth arrest in a long-term survivor of acute lymphoblastic leukemia

Growth arrest at the secondary growth plate, also known as the acrophysis, is a rare phenomenon with only very few known published case reports. We report on a case of formation of ghost secondary ossification centers at the acrophyses of the knee joint in a 14-year-old female, who survived early childhood acute lymphoblastic leukemia. The patient suffered from severe side effects from both disease and subsequent treatment strategies with a 10-month immobilization period as a consequence at the age of 3 years. The ghost secondary ossification centers were encountered on radiographs and MRI 10 years later, when she presented for evaluation of chronic pain in her left knee related to sports activities, due to a meniscal cyst. Awareness of this phenomenon is nevertheless important, because it seems that endochondral bone growth recovery at the acrophyses might be different from recovery in physes, because we found no concomitant sequelae of growth arrest in the metaphyses