Development and Evaluation of a Highly Effective Gas Particle Partitioner with Minimal Effect on the Gas Composition

Particle free air is required in a wide range of scientific and technical applications such as pre-filtering for gas analysers or for the artefact correction of particle mass concentration measurements. Most common processes for the removal of particles from a gas stream are filtration and electrostatic precipitation. However, both mechanisms introduce changes to the thermodynamic conditions and/or the composition of the gas, which might be detrimental to the downstream measurement of gas or particle concentrations. For highly efficient separation of gas and particles with no changes of the thermodynamic conditions and substantially no changes to the gas phase, a coaxial Gas Particle Partitioner (GPP) has been developed and intensively tested. The GPP utilizes corona charging to electrically charge the particles and a strong electric field in a separate unit to take them out of the sample flow when switched on. The corona was optimised with respect to gas formation, i.e. a gold wire of only 25 µm is used as corona electrode along with positive corona polarity. Additionally, the vicinity of the corona wire gets continuously flushed by means of a wash flow, which is spatially separated from the sample flow, to prevent gases formed by the corona, such as ozone and oxides of nitrogen from reaching the sample aerosol flow. Inside the GPP, the total aerosol flow is split into a sample flow and an excess gas flow. The splitting of the flow ensures that evaporation or release of particles, deposited on the outer wall does not affect the sample flow but only the excess gas flow. The flow splitter is designed such that the particle size distribution in the sample flow is identical to the ambient distribution, when the GPP is switched off. When switched on, the sample flow is particle free. The laboratory investigations have shown that the GPP is able to separate gas and particles with an efficiency of near 100% in the particle size range of 25 nm < dp < 10.7 µm. For particle sizes below 25 nm, the separation efficiency decreased with decreasing particle size. The measures for a minimization of the influence of the corona on the gas composition have led to substantially reduced O3 and NOx concentrations in the sample flow. Compared to the worst case (100 µm gold wire, negative polarity, no wash flow) the additional ozone concentration could be reduced by 98.5% and the nitrogen dioxide concentration by approx. 90%

Nanoparticle exposure at nanotechnology workplaces: A review

Risk, associated with nanomaterial use, is determined by exposure and hazard potential of these materials. Both topics cannot be evaluated absolutely independently. Realistic dose concentrations should be tested based on stringent exposure assessments for the corresponding nanomaterial taking into account also the environmental and product matrix. This review focuses on current available information from peer reviewed publications related to airborne nanomaterial exposure. Two approaches to derive realistic exposure values are differentiated and independently presented; those based on workplace measurements and the others based on simulations in laboratories. An assessment of the current available workplace measurement data using a matrix, which is related to nanomaterials and work processes, shows, that data are available on the likelihood of release and possible exposure. Laboratory studies are seen as an important complementary source of information on particle release processes and hence for possible exposure. In both cases, whether workplace measurements or laboratories studies, the issue of background particles is a major problem. From this review, major areas for future activities and focal points are identified

How can nanobiotechnology oversight advance science and industry: examples from environmental, health, and safety studies of nanoparticles (nano-EHS)

Nanotechnology has great potential to transform science and industry in the fields of energy, material, environment, and medicine. At the same time, more concerns are being raised about the occupational health and safety of nanomaterials in the workplace and the implications of nanotechnology on the environment and living systems. Studies on environmental, health, and safety (EHS) issues of nanomaterials have a strong influence on public acceptance of nanotechnology and, eventually, affect its sustainability. Oversight and regulation by government agencies and non-governmental organizations (NGOs) play significant roles in ensuring responsible and environmentally friendly development of nanotechnology. The EHS studies of nanomaterials can provide data and information to help the development of regulations and guidelines. We present research results on three aspects of EHS studies: physico-chemical characterization and measurement of nanomaterials; emission, exposure, and toxicity of nanomaterials; and control and abatement of nanomaterial releases using filtration technology. Measurement of nanoparticle agglomerates using a newly developed instrument, the Universal NanoParticle Analyzer (UNPA), is discussed. Exposure measurement results for silicon nanoparticles in a pilot scale production plant are presented, as well as exposure measurement and toxicity study of carbon nanotubes (CNTs). Filtration studies of nanoparticle agglomerates are also presented as an example of emission control method

Emission measurement and safety assessment for the production process of silicon nanoparticles in a pilot-scale facility

Emission into the workplace was measured for the production process of silicon nanoparticles in a pilot-scale facility at the Institute of Energy and Environmental Technology e.V. (IUTA). The silicon nanoparticles were produced in a hot-wall reactor and consisted of primary particles around 60nm in diameter. We employed real-time aerosol instruments to measure particle number and lung-deposited surface area concentrations and size distribution; airborne particles were also collected for off-line electron microscopic analysis. Emission of silicon nanoparticles was not detected during the processes of synthesis, collection, and bagging. This was attributed to the completely closed production system and other safety measures against particle release which will be discussed briefly. Emission of silicon nanoparticles significantly above the detection limit was only observed during the cleaning process when the production system was open and manually cleaned. The majority of the detected particles was in the size range of 100-400nm and were silicon nanoparticle agglomerates first deposited in the tubing then re-suspended during the cleaning process. Appropriate personal protection equipment is recommended for safety protection of the workers during cleanin

System Identification Method for Brake Particle Emission Measurements of Passenger Car Disc Brakes on a Dynamometer

Besides particulate emissions from engine exhausts, which are already regulated by emission standards, passenger car disc brakes are a source of particulate matter. With the current car fleet it is estimated that up to 21% of the total traffic related PM10 emissions in urban environments originate from brake wear and reduction of brake dust emissions is subject of current research. For the purpose of reducing brake dust emissions by choosing low-emission operating points of the disc brake, the knowledge of the emission behavior depending on brake pressure, wheel speed, temperature and friction history is of interest. According to the current state of research, theoretical white box modeling of the emission behavior is complicated due to the complexity of tribological contact between pad and disc. Thus experimental black box modeling is supposed to describe emission behavior. In order to minimize the influence of disturbances and therefore to improve prediction accuracy of such empirical models, system identification methods based on periodical test signals, such as brake pressure sine, are used for this application. To adopt these test signals, which are established in transfer function measurements, to the application of brake particle measurements and to develop an experimental design, system theoretical quantities, such as cutoff frequency, signal to noise ratio and hysteresis, are determined in dynamometer tests. Therefore measurements of the system’s response to step and sine test signals are analyzed. System identification is executed and the applicability of periodical test signals to brake particle measurements is proven

ICD Shock, Not Ventricular Fibrillation, Causes Elevation of High Sensitive Troponin T after Defibrillation Threshold Testing-The Prospective, Randomized, Multicentre TropShock-Trial

Background The placement of an implantable cardioverter defibrillator (ICD) has become routine practice to protect high risk patients from sudden cardiac death. However, implantation-related myocardial micro-damage and its relation to different implantation strategies are poorly characterized. Methods A total of 194 ICD recipients (64 +/- 12 years, 83% male, 95% primary prevention of sudden cardiac death, 35% cardiac resynchronization therapy) were randomly assigned to one of three implantation strategies: (1) ICD implantation without any defibrillation threshold (DFT) testing,(2) estimation of the DFT without arrhythmia induction (modified "upper limit of vulnerability (ULV) testing") or (3) traditional safety margin testing including ventricular arrhythmia induction. High-sensitive Troponin T (hsTnT) levels were determined prior to the implantation and 6 hours after. Results All three groups showed a postoperative increase of hsTnT. The mean delta was 0.031 +/- 0.032 ng/ml for patients without DFT testing, 0.080 +/- 0.067 ng/ml for the modified ULV-testing and 0.064 +/- 0.056 ng/ml for patients with traditional safety margin testing. Delta hsTnT was significantly larger in both of the groups with intraoperative ICD testing compared to the non-testing strategy (p<0.001 each). There was no statistical difference in delta hsTnT between the two groups with intraoperative ICD testing (p = 0.179). Conclusion High-sensitive Troponin T release during ICD implantation is significantly higher in patients with intraoperative ICD testing using shock applications compared to those without testing. Shock applications, with or without arrhythmia induction, did not result in a significantly different delta hsTnT. Hence, the ICD shock itself and not ventricular fibrillation seems to cause myocardial micro-damage

Measurement Methods for Nanoparticles in Indoor and Outdoor Air

International audienceA large variety of measurement methods for the characterization of airborne nanoparticles in indoor or outdoor air exist. The choice of an appropriate method depends strongly on the questions to be tackled. If the aerosol is to be characterized only for a single location, one may use stationary equipment that is rather bulky but provides the most details and is most accurate. Spatially resolved measurements can only be conducted with portable or personal measurement equipment which provide a limited dataset with lower accuracy. Furthermore, the metrics to be measured (e.g., number, surface area of mass concentration, chemical composition, etc.) determine the choice of measurement methods as no single method can do it all. Another determining factor is the time resolution of the instruments. While direct-reading monitors deliver the information with high time resolution (often 1 s) and hence allow for linking the measured concentration to certain activities, samplers collect the particles for subsequent analyses and therefore provide an average over the sampling time. Consequently, the choice of a measurement instrument for the characterization of airborne nanoparticles remains a compromise. In many practical applications, the combination of different techniques may be required

Development of a Method to Determine the Fractional Deposition Efficiency of Full-Scale HVAC and HEPA Filter Cassettes for Nanoparticles ≥3.5 nm

Novel methods have been developed to measure the fractional deposition efficiency for nanoparticles of full-scale HVAC and HEPA filter cassettes down to a particle size of 3.5 nm. The methods use a flame spray nanoparticle generator to produce NaCl test aerosols with narrow size distributions and very high concentrations. While the efficiency curves of lower efficiency filters of classes F7 and E10 were still able to be determined by measuring the size distributions of the polydisperse test aerosols upstream and downstream of the filter, two new testing procedures were developed for high efficiency filters of class H13. One considers the narrow size distributions of the test aerosols as quasi-monodisperse and follows a similar approach like EN 1822 for flat sheet media. The second one evaluates mobility classified fractions of the quasi-monodisperse test aerosols. A dedicated multiple charge correction scheme was developed to account for the effect of multiply charged particles. While the latter procedure allows to extend the particle size range, the prior significantly reduces the measurement time. All tests delivered meaningful results, which were very comparable with the results from flat sheet media tests