scholarly journals Results and recommendations from an intercomparison of six Hygroscopicity-TDMA systems

2011 ◽  
Vol 4 (3) ◽  
pp. 485-497 ◽  
Author(s):  
A. Massling ◽  
N. Niedermeier ◽  
T. Hennig ◽  
E. O. Fors ◽  
E. Swietlicki ◽  
...  
Keyword(s):  
Ammonium Sulphate ◽  
Particle Diameter ◽  
Data Evaluation ◽  
Evaluation Procedure ◽  
Atmospheric Measurements ◽  
Size Dependent ◽  
Evaluation Procedures ◽  
Individual System ◽  
Correct Determination

Abstract. The performance of six custom-built Hygrocopicity-Tandem Differential Mobility Analyser (H-TDMA) systems was investigated in the frame of an international calibration and intercomparison workshop held in Leipzig, February 2006. The goal of the workshop was to harmonise H-TDMA measurements and develop recommendations for atmospheric measurements and their data evaluation. The H-TDMA systems were compared in terms of the sizing of dry particles, relative humidity (RH) uncertainty, and consistency in determination of number fractions of different hygroscopic particle groups. The experiments were performed in an air-conditioned laboratory using ammonium sulphate particles or an external mixture of ammonium sulphate and soot particles. The sizing of dry particles of the six H-TDMA systems was within 0.2 to 4.2% of the selected particle diameter depending on investigated size and individual system. Measurements of ammonium sulphate aerosol found deviations equivalent to 4.5% RH from the set point of 90% RH compared to results from previous experiments in the literature. Evaluation of the number fraction of particles within the clearly separated growth factor modes of a laboratory generated externally mixed aerosol was done. The data from the H-TDMAs was analysed with a single fitting routine to investigate differences caused by the different data evaluation procedures used for each H-TDMA. The differences between the H-TDMAs were reduced from +12/−13% to +8/−6% when the same analysis routine was applied. We conclude that a common data evaluation procedure to determine number fractions of externally mixed aerosols will improve the comparability of H-TDMA measurements. It is recommended to ensure proper calibration of all flow, temperature and RH sensors in the systems. It is most important to thermally insulate the aerosol humidification unit and the second DMA and to monitor these temperatures to an accuracy of 0.2 °C. For the correct determination of external mixtures, it is necessary to take into account size-dependent losses due to diffusion in the plumbing between the DMAs and in the aerosol humidification unit.

scholarly journals Results and recommendations from an intercomparison of six Hygroscopicity-TDMA systems

2010 ◽  
Vol 3 (1) ◽  
pp. 637-674
Author(s):  
A. Massling ◽  
N. Niedermaier ◽  
T. Hennig ◽  
E. Fors ◽  
E. Swietlicki ◽  
...  
Keyword(s):  
Ammonium Sulfate ◽  
Particle Diameter ◽  
Control Unit ◽  
Data Evaluation ◽  
Evaluation Procedure ◽  
Hygroscopic Growth ◽  
Atmospheric Measurements ◽  
Individual System ◽  
Correct Determination

Abstract. The performance of six custom-built Hygrocopicity-Tandem Differential Mobility Analyzers (H-TDMA) systems was investigated in the frame of an international calibration and intercomparison workshop held in Leipzig, February 2006. The goal of the workshop was to harmonize H-TDMA measurements and develop recommendations for atmospheric measurements and their data evaluation. The H-TDMA systems were compared in terms of the sizing of dry particles, relative humidity (RH) uncertainty and consistency in determination of number fractions of different hygroscopic particle groups. The experiments were performed in an air-conditioned laboratory using ammonium sulfate particles or an external mixture of ammonium sulfate and soot particles. The sizing of dry particles of the six H-TDMA systems was within 0.2 to 4.2% of the selected particle diameter depending on investigated size and individual system. With regard to RH uncertainties, the H-TDMA systems showed deviations up to 4.5% RH from the set point at RH=90% investigating the hygroscopic growth of ammonium sulfate particles and comparing the results with theory. The evaluation of number fractions investigating an externally mixed aerosol delivered differences up to +/−8% in calculated number fraction for one and the same aerosol type. We analysed the datasets of the different H-TDMAs with one fitting routine to investigate differences caused by the different data evaluation procedures. The results showed that the differences were reduced from +12/−13% to +8/−6%. We can conclude here that a common data evaluation procedure to determine the number fraction of externally mixed aerosols will improve the comparability of H-TDMA measurements. We finally recommend, to ensure a good calibration of all flow, temperature and RH sensors in the systems. It is most important to thermally insulate the RH control unit and the second DMA and to monitor those temperatures as accurately as 0.2 °C. For a correct determination of external mixtures, it is necessary to take into account size-dependent losses due to the diffusion in the pluming between the DMAs and in the aerosol humidification unit.

Ultrasonic Evaluation of "Silent Regions" in the Thyroid Scintiscan

1978 ◽  
Vol 17 (01) ◽  
pp. 16-23 ◽  
Author(s):  
Ch. L. Zollikofer ◽  
J. Wewerka ◽  
Th. Frank
Keyword(s):  
Needle Biopsy ◽  
Clinical Course ◽  
Stimulation Test ◽  
Evaluation Procedure ◽  
Sonographic Diagnosis ◽  
Non Invasive ◽  
Evaluation Procedures ◽  
Ultrasonic Evaluation ◽  
Invasive Evaluation ◽  
Autonomous Adenoma

35 patients with scintigraphically silent thyroid regions without palpable cold nodules were further evaluated by ultrasonography. In 33 cases the sonographic diagnosis was confirmed by other examinations or the clinical course. 2 cases were misinterpreted right at the beginning of our series.The use of ultrasonography in evaluating silent thyroid regions in the totally decompensated autonomous adenoma, in unilateral thyroid aplasia, thyroiditis and hyperthyroidism is shown to be a reliable and valuable supplement to the clinical and radioisotopic evaluation procedures. When differentiating the totally decompensated autonomous adenoma from unilateral thyroid aplasia a stimulation test need not be performed in most cases. Suspected thyroiditis can be confirmed in a simple way. Being a non-invasive evaluation procedure, ultrasonography should be used before performing a needle biopsy.

scholarly journals Manufacturing PLA/PCL Blends by Ultrasonic Molding Technology

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2412
Author(s):  
Inés Ferrer ◽  
Ariadna Manresa ◽  
José Alberto Méndez ◽  
Marc Delgado-Aguilar ◽  
Maria Luisa Garcia-Romeu
Keyword(s):  
Molecular Weight ◽  
Crystallization Rate ◽  
Raw Material ◽  
Small Particle Size ◽  
Polymer Mixtures ◽  
Crystallinity Degree ◽  
Correct Determination ◽  
Production Stages ◽  
Process Speed

Ultrasonic molding (USM) is a good candidate for studying the plasticization of polymer mixtures or other composite materials due to either the little amount of material needed for processing, low waste or the needed low pressure and residence time of the mold. Thus, the novelty of this research is the capability of USM technology to process PLA/PCL blends and their corresponding neat materials, encompassing all the production stages, from raw material to the final specimen. The major findings of the work revealed that the thermal properties of the blends were not affected by the USM process, although the crystallinity degree experienced variations, decreasing for PLA and increasing for PCL, which was attributed to the crystallization rate of each polymer, the high process speed, the short cooling time and the small particle size. The employed ultrasonic energy increased the molecular weight with low variations through the specimen. However, the degradation results aligned with the expected trend of these material blends. Moreover, this study also showed the effect pellet shape and dimensions have over the process parameters, as well as the effect of the blend composition. It can be concluded that USM is a technology suitable to successfully process PLA/PCL blends with the correct determination of process parameter windows.

Evaluation of methods for detection of β-lactamase production in MSSA

2021 ◽  
Author(s):  
Robert Skov ◽  
David R Lonsway ◽  
Jesper Larsen ◽  
Anders Rhod Larsen ◽  
Jurgita Samulioniené ◽  
...  
Keyword(s):  
Susceptibility Testing ◽  
Confirmatory Test ◽  
Disc Diffusion ◽  
Broth Microdilution ◽  
Confirmatory Tests ◽  
Correct Determination ◽  
Primary Test ◽  
Zone Edge ◽  
Evaluation Of Methods

Abstract Objectives Correct determination of penicillin susceptibility is pivotal for using penicillin in the treatment of Staphylococcus aureus infections. This study examines the performance of MIC determination, disc diffusion and a range of confirmatory tests for detection of penicillin susceptibility in S. aureus. Methods A total of 286 consecutive penicillin-susceptible S. aureus blood culture isolates as well as a challenge set of 62 MSSA isolates were investigated for the presence of the blaZ gene by PCR and subjected to penicillin-susceptibility testing using broth microdilution MIC determination, disc diffusion including reading of the zone edge, two nitrocefin tests and the cloverleaf test. Results Using PCR-based detection of blaZ as the gold standard, both broth microdilution MIC testing and disc diffusion testing resulted in a relatively low accuracy (82%–93%) with a sensitivity ranging from 49%–93%. Among the confirmatory tests, the cloverleaf test performed with 100% accuracy, while zone edge interpretation and nitrocefin-based tests increased the sensitivity of β-lactamase detection to 96%–98% and 82%–96% when using MIC determination or disc diffusion as primary test, respectively. Conclusions This investigation showed that reliable and accurate detection of β-lactamase production in S. aureus can be obtained by MIC determination or penicillin disc diffusion followed by interpretation of the zone edge as a confirmatory test for apparently penicillin-susceptible isolates. The more cumbersome cloverleaf test can also be used. Nitrocefin-based tests should not be used as the only test for confirmation of a presumptive β-lactamase-negative isolate.

IMPROVEMENT OF THE CAMERAL CHECKS PROCESS IN RUSSIA BASED ON FOREIGN EXPERIENCE

2020 ◽  
Author(s):  
Darya Sergeevna Kareva ◽  
◽  
Sevinj Mahmud kyzy Ismailova ◽  
Elena Evgenievna Dozhdva ◽  
◽  
...  
Keyword(s):  
United States ◽  
The United States ◽  
Foreign Experience ◽  
Correct Determination

The article substantiates the need to reform cameral tax control in Russia based on the experience of the United States. The necessity of introducing into the procedure of cameral control the mechanism of requesting all documents confirming the correct determination of tax obligations is determined. The aim of improving the process of desk audits of control is that the new procedure for conducting audits will reduce the likelihood of tax violations.

scholarly journals Size Dependent CO2 Reduction Activity of Ag Nanoparticle Electrocatalysts

2021 ◽  
Author(s):  
Xingyi Deng ◽  
Dominic Alfonso ◽  
Thuy-Duong Nguyen-Phan ◽  
Douglas Kauffman
Keyword(s):  
Active Sites ◽  
Density Functional ◽  
Particle Diameter ◽  
Small Diameter ◽  
Co2 Reduction ◽  
High Population ◽  
Structure Property ◽  
Size Dependent ◽  
Catalyst Utilization ◽  
Ag Catalysts

Abstract Coinage metals (Au, Cu and Ag) are state-of-the-art electrocatalysts for the CO2 reduction reaction (CO2RR). Size-dependent CO2RR activity of Au and Cu has been studied, and increased H2 evolution reaction (HER) activity is expected for small catalyst particles with high population of undercoordinated corner sites. A similar consensus is still lacking for Ag catalysts because the ligands and stabilizers typically used to control particle synthesis can block specific active sites and mask inherent structure-property trends. This knowledge gap is problematic because increased performance and catalyst utilization are still needed to improve economic viability. We combined density functional theory, microkinetic modeling, and experiment to demonstrate a strong size-dependence for pristine Ag particles in the sub-10 nm range. Small diameter particles with a high population of Ag edge sites were predicted to favor HER, whereas CO2RR selectivity increased towards that of bulk Ag for larger diameter particles as the population of Ag(100) surface sites grew. Experimental results validated these predictions and we identified an optimal particle diameter of 8-10 nm that balanced selectivity and activity. Particles below this diameter suffered from poor selectivity, while larger particles demonstrated bulk-like activity and reduced catalyst utilization. These results demonstrate the size-dependent CO2RR activity of pristine Ag catalysts and will help guide future development efforts.

scholarly journals Long-term observations of tropospheric particle number size distributions and equivalent black carbon mass concentrations in the German Ultrafine Aerosol Network (GUAN)

2016 ◽  
Vol 8 (2) ◽  
pp. 355-382 ◽  
Author(s):  
Wolfram Birmili ◽  
Kay Weinhold ◽  
Fabian Rasch ◽  
André Sonntag ◽  
Jia Sun ◽  
...  
Keyword(s):  
Black Carbon ◽  
Particle Number ◽  
Measurement Data ◽  
Urban Traffic ◽  
Data Evaluation ◽  
Size Distributions ◽  
Evaluation Procedures ◽  
Carbon Mass ◽  
Ultrafine Aerosol ◽  
Mass Concentrations

Abstract. The German Ultrafine Aerosol Network (GUAN) is a cooperative atmospheric observation network, which aims at improving the scientific understanding of aerosol-related effects in the troposphere. The network addresses research questions dedicated to both climate- and health-related effects. GUAN's core activity has been the continuous collection of tropospheric particle number size distributions and black carbon mass concentrations at 17 observation sites in Germany. These sites cover various environmental settings including urban traffic, urban background, rural background, and Alpine mountains. In association with partner projects, GUAN has implemented a high degree of harmonisation of instrumentation, operating procedures, and data evaluation procedures. The quality of the measurement data is assured by laboratory intercomparisons as well as on-site comparisons with reference instruments. This paper describes the measurement sites, instrumentation, quality assurance, and data evaluation procedures in the network as well as the EBAS repository, where the data sets can be obtained (doi:10.5072/guan).

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