607 research outputs found
Proceedings of the 4th International Conference and Exhibition: World Congress on Superconductivity, Volume 2
This document contains papers presented at the 4th International Conference Exhibition: World Congress on Superconductivity held June 27-July 1, 1994 in Orlando, Florida. These documents encompass research, technology, applications, funding, political, and social aspects of superconductivity. The areas covered included: high-temperature materials; thin films; C-60 based superconductors; persistent magnetic fields and shielding; fabrication methodology; space applications; physical applications; performance characterization; device applications; weak link effects and flux motion; accelerator technology; superconductivity energy; storage; future research and development directions; medical applications; granular superconductors; wire fabrication technology; computer applications; technical and commercial challenges; and power and energy applications
Proceedings of the 4th International Conference and Exhibition: World Congress on Superconductivity, volume 1
The papers presented at the 4th International Conference Exhibition: World Congress on Superconductivity held at the Marriott Orlando World Center, Orlando, Florida, are contained in this document and encompass the research, technology, applications, funding, political, and social aspects of superconductivity. Specifically, the areas covered included: high-temperature materials; thin films; C-60 based superconductors; persistent magnetic fields and shielding; fabrication methodology; space applications; physical applications; performance characterization; device applications; weak link effects and flux motion; accelerator technology; superconductivity energy; storage; future research and development directions; medical applications; granular superconductors; wire fabrication technology; computer applications; technical and commercial challenges, and power and energy applications
Penalty-free feasibility boundary convergent multi-objective evolutionary algorithm for the optimization of water distribution systems
This paper presents a new penalty-free multi-objective evolutionary approach (PFMOEA) for the optimization of water distribution systems (WDSs). The proposed approach utilizes pressure dependent analysis (PDA) to develop a multi-objective evolutionary search. PDA is able to simulate both normal and pressure deficient networks and provides the means to accurately and rapidly identify the feasible region of the solution space, effectively locating global or near global optimal solutions along its active constraint boundary. The significant advantage of this method over previous methods is that it eliminates the need for ad-hoc penalty functions, additional “boundary search” parameters, or special constraint handling procedures. Conceptually, the approach is downright straightforward and probably the simplest hitherto. The PFMOEA has been applied to several WDS benchmarks and its performance examined. It is demonstrated that the approach is highly robust and efficient in locating optimal solutions. Superior results in terms of the initial network construction cost and number of hydraulic simulations required were obtained. The improvements are demonstrated through comparisons with previously published solutions from the literature
Centrifugal Pump Operation, Maintenance, and Reliability
Discussion GroupRepair Specs, use, in house repair specs
Lube oil storage and usage
Mechanical seals and bearings issues
Pump monitoring how are we doing this and how do we want to do this
Craft training precision maintenance
Best practices for pump maintenance; Back pullout vs. pulling entire pump:
Open bearing housings vs sealed wet sump
Seal plan which was not expected wrong for the application
Preventive/predictive technologies
Off design operation
Mean time between failure (MTBF), other KPIs how do we measure, and how do we use the metrics
How to create pump reliability in an unreliable plant
Seal-less versus sealed pump reliability, canned motor pumps versus mag drive pump reliability
Mechanical Integrity Inspections of VS 6 pumps in hydrocarbon service
Seals in light hydrocarbon service operations, risk, leak response, maintenance
Pump predictive/preventive maintenance program elements philosophy, frequencies.
Measures of effectiveness of preventive and predictive programs for pumps
Roles of operations and maintenance/reliability in improvements and data collection
Reliability experience with liquid versus non contacting gas seals applications
Maintenance philosophy for pumps what constitutes best practices
Spare parts OEM versus non-OEM
Repairs OEM versus non-OEM service facilities
Pump foundation, alignment and pipe strain influence of reliability
Impact of corporate purchasing alliances on pump reliability
a. Repair facilities alliances
b. New equipment purchasing alliances
Repair techniques and material improvements
Portable and on-line monitoring impact on reliability
Wireless monitoring impact on reliability and risk of failure
Optimization of thrust bearings configuratio
Sudden Cardiac Death: Epidemiology, Pathogenesis and Management
Sudden cardiac death (SCD) is an unexpected sudden death due to a heart condition, that occurs within one hour of symptoms onset. SCD is a leading cause of death in western countries, and is responsible for the majority of deaths from cardiovascular disease. Moreover, SCD accounts for mortality in approximately half of all coronary heart disease patients. Nevertheless, the recent advancements made in screening, prevention, treatment, and management of the underlying causes has decreased this number. In this article, we sought to review established and new modes of screening patients at risk for SCD, treatment and prevention of SCD, and the role of new technologies in the field. Further, we delineate the current epidemiologic trends and pathogenesis. In particular, we describe the advancement in molecular autopsy and genetic testing, the role of target temperature management, extracorporeal membrane oxygenation (ECMO), cardiopulmonary resuscitation (CPR), and transvenous and subcutaneous implantable cardioverter devices (ICDs)
Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study
Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world.
Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231.
Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001).
Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication
Dramatic rate-enhancement of oxygen atom transfer by an iron(iv)-oxo species by equatorial ligand field perturbations
Nonheme iron dioxygenases are efficient enzymes with relevance for human health that regio- and stereospecifically transfer an oxygen atom to substrates. How they perform this task with such selectivity remains unknown, but may have to do with substrate binding, positioning and oxidant approach. To understand substrate approach on a catalytic reaction centre, we investigated the structure and reactivity of a biomimetic oxidant with ligand features that affect the interactions between oxidant and substrate. Thus, we report here the synthesis and characterization of an iron(IV)-oxo complex with pentadentate nonheme ligand, where structurally induced perturbations in the equatorial ligand field affect the spectroscopy and reactivity of the complex. We tested the activity of the complex with respect to oxygen atom transfer to and hydrogen atom abstraction from substrates. This oxidant shows improved reaction rates toward heteroatom oxidation with respect to the nonsubstituted ligand complex by ∼104 fold. The origin of the enhanced reactivity is explained with a series of density functional theory studies that show an enhanced electron affinity of the oxidant through equatorial ligand perturbations
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