Metalloporphyrins inactivate caspase-3 and -8

Activation of caspases represents one of the earliest biochemical indicators for apoptotic cell death. Therefore, measurement of caspase activity is a widely used and generally accepted method to determine apoptosis in a wide range of in vivo and in vitro settings. Numerous publications characterize the role of the heme-catabolizing enzyme heme oxygenase-1 (HO-1) in regulating apoptotic processes. Different metalloporphyrins representing inducers and inhibitors of this enzyme are often used, followed by assessment of apoptotic cell death. In the present work, we found that caspase-3-like activity, as well as activity of caspase-8 measured in either Fas (CD95) ligand-treated Jurkat T-lymphocytes or by the use of recombinant caspase-3 or -8, was inhibited by different metalloporphyrins (cobalt(III) protoporphyrin IX, tin and zinc II) protoporphyrin-IX). Moreover, employing the mouse model of Fas-induced liver apoptosis these properties of porphyrins could also be demonstrated in vivo. The metalloporphyrins were shown to inhibit caspase-3-mediated PARP cleavage. Molecular modeling studies demonstrated that porphyrins can occupy the active site of caspase-3 in an energetically favorable manner and in a binding mode similar to that of known inhibitors. The data shown here introduce metalloporphyrins as direct inhibitors of caspase activity. This finding points to the need for careful employment of metalloporphyrins as modulators of HO-1

High-Speed LIF Imaging for Cycle-Resolved Formaldehyde Visualization in HCCI Combustion

High-speed laser diagnostics was utilized for singlecycle resolved studies of the formaldehyde distribution in the combustion chamber of an HCCI engine. A multi- YAG laser system consisting of four individual Qswitched, flash lamp-pumped Nd:YAG lasers has previously been developed in order to obtain laser pulses at 355 nm suitable for performing LIF measurements of the formaldehyde molecule. Bursts of up to eight pulses with very short time separation can be produced, allowing capturing of LIF image series with high temporal resolution. The system was used together with a high-speed framing camera employing eight intensified CCD modules, with a frame-rate matching the laser pulse repetition rate. The diagnostic system was used to study the combustion in a truck-size HCCI engine, running at 1200 rpm using n-heptane as fuel. By using laser pulses with time separations as short as 7

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Laser Spectroscopic Techniques for Combustion Diagnostics Directed Towards Industrial Applications

In the work presented in the thesis, different laser spectroscopic techniques were utilized for measurement of species concentrations, as well as for surface thermometry. Experiments were conducted in various combustion environments, ranging from laboratory burners to truck-sized internal combustion (IC) engines, gas turbine combustors and a full-size aircraft turbofan engine. A multiple Nd:YAG laser system generating rapid bursts of laser pulses, and a high-speed framing camera capable of recording sequences of up to eight images, were used to study flame species and fuel distributions with a high temporal resolution in flames, combustion cells and IC engines. The spatial and temporal evolution of the ignition process of a jet of hot gases impinging upon an initially quiescent hydrogen/air mixture was investigated by means of high-speed planar laser-induced fluorescence (PLIF) of the OH radical. In addition, high-speed OH PLIF was employed for tracking flame-front movements in a low-swirl methane/air flame. Simultaneous measurements of the velocity fields, as well as temperature-field imaging were also conducted. A multiple dye-laser system that was set up was employed for the OH PLIF experiments in the low-swirl flame. Each of the four dye lasers was pumped by an individual laser from the Nd:YAG cluster, producing tunable laser radiation without losses in laser-pulse energy or deterioration of the beam intensity profiles, which can occur when only a single dye laser is employed. The multiple Nd:YAG laser system and the high-speed framing camera were used for single-cycle-resolved studies of combustion processes in a homogeneous charge compression ignition (HCCI) engine. In-cylinder fuel distributions were investigated by means of fuel tracer PLIF in order to study the effects of combustion chamber geometry on combustion. Two different piston geometries were compared, clear differences between them in the onset and development of combustion being revealed. High-speed formaldehyde PLIF was also used to study the HCCI combustion. The low-temperature reactions and the early phase of the main combustion event were investigated by monitoring the formation and the consumption of formaldehyde, respectively. The experiments showed the possibilities of using formaldehyde as a naturally occurring fuel marker in HCCI combustion. In addition, studies of laser-spark- and spark-plug-assisted HCCI were carried out, the results being compared with those for conventional HCCI operation. Different optical and laser-based techniques were utilized for characterization of the afterburner of an aircraft turbofan engine. Fuel PLIF measurements were performed in the burning jet stream, close to the afterburner outlet, to investigate the extent to which unburned fuel exits from the engine. Laser-induced phosphorescence from thermographic phosphors was used for assessing surface temperatures at various locations in the afterburner. Since measurements were conducted over the entire load augmentation of the engine, temperature variations during full load transients could be studied. The laser spectroscopic techniques proved to be applicable in the extremely harsh environment prevailing inside and next to a jet engine operating at high afterburner loads. Additional work, related to gas turbine diagnostics included two-phase fuel visualization using simultaneous Mie scattering and LIF for characterizing a Jet-A fueled pilot burner. PLIF imaging for the visualization of flame-front regions (OH) and of fuel distribution in an industrial gas turbine burner operating on natural gas was also performed. The spatial resolution of a chemiluminescence sensor designed for monitoring spatial and temporal fluctuations in the equivalence ratio in industrial gas turbine combustors was investigated as well, the sensor being evaluated in terms of its capability, as compared with OH PLIF, of resolving flame fronts (OH*)

Laser-induced Phosphorescence for Surface Thermometry in the Afterburner of an Aircraft Engine

In the present work, surface thermometry using a method based on the spectroscopy of inorganic luminescent material was applied in the afterburner of a full-size aircraft jet engine. The technique uses laser-induced emission from thermographic phosphors for nonintrusive remote temperature diagnostics in combustion applications with high sensitivity and accuracy. A phosphor material having suitable temperature sensitivity in the expected temperature range was applied to the surface of interest in the engine afterburner. Phosphorescence radiation was generated using the forth harmonic (266 nm) from a pulsed Nd:YAG laser. The resulting signal was detected with a photomultiplier tube and phosphorescence lifetime decay curves were recorded for various engine loads, including operation of the afterburner. By analyzing the phosphorescence decay, temperature data were acquired through implementation of a regression equation extracted from well-defined calibration measurements on the phosphor used. Quantitative temperature data recorded with a repetition rate of 10 Hz are presented. The laser-induced phosphorescence technique for surface thermometry has proven its applicability in the extremely harsh environment prevailing inside and next to a jet engine operating at full load

Surface thermometry using laser-induced phosphorescence applied in the afterburner of an aircraft turbofan engine

In the present work surface thermometry using a method based on the spectroscopy of inorganic luminescent material has been applied in a full-size aircraft jet engine. The technique utilizes laser-induced emission from thermographic phosphors for, non-intrusive, remote temperature diagnostics in combustion applications with high sensitivity and accuracy. In the present application the laser-induced phosphorescence technique has proven its applicability even in the extremely harsh environment prevailing next to a jet engine operating at full load. The measurement object, Volvo RM12, is based on the General Electric F404 engine, from which it has been developed to meet single-engine operating criteria and achieve higher performance. A phosphor material having suitable temperature sensitivity in the expected temperature range was applied to the surface of interest on the flameholder of the engine afterburner. Phosphorescence radiation was generated using the forth harmonic (266 nm) from a pulsed Nd:YAG laser as an excitation source. The resulting signal was detected with a photo multiple tube (PMT). Phosphorescence lifetime decay curves were recorded at various load of the engine, including use of the afterburner. By analyzing the lifetime decay, the temperature data was acquired through implementation of a regression equation extracted from well-defined calibration measurements on the phosphor used

Optical diagnostics for characterization of a full-size fighter-jet afterburner

In the present work the feasibility of using various optical/laser based techniques for characterization of the afterburner of a full-size aircraft engine have been investigated. The tests have been performed on-site at Volvo Aero Corporation and were mainly directed towards surface thermometry using thermographic phosphors and fuel visualization. All applications were studied for different engine running conditions, including various use of the afterburner (A/B). Laser-Induced Fluorescence (LIF) was employed for fuel visualization to investigate to what extent unburned fuel exits the afterburner. Laser-Induced Phosphorescence (LIP) from thermographic phosphors was used to measure two-dimensional surface temperatures on the outlet nozzle of the afterburner. In addition, the spectral characteristics of the burning jet stream were investigated. Copyrigh

Optical Investigations of the Combustion Characteristics of a Gas Turbine Pilot Burner

This paper presents the application of several optical measurement techniques for the characterization of the combustion behavior of the pilot burner of a gas turbine combustor developed according to the lean premixed prevaporized concept. The vaporization of the kerosene fuel (Jet-A) injected by a pilot spray and its consequent mixing with air has been visualized using combined laser-induced fluorescence and Mie scattering measurements. The laser-induced fluorescence/Mie measurements can be used to estimate the length and time scales for evaporation and mixing with air of kerosene (Jet-A) for the lean, premixed, and prevaporized pilot burner. In addition, the feasibility of using laser-induced incandescence for soot characterization has been investigated. Finally, spontaneous flame emission (i.e., chemiluminescence and thermal radiation) have been measured providing information on the overall characteristics of the combustion.This work was supported by the European Union through the project entitled Low Pollutant Combustor Technology Program (LOPOCOTEP Contract G4RD-CT-2001-00447) and via the European Union (EU) Large Scale Facility in Combustion at Lund.Peer reviewe