Electret filters are widely used in HVAC systems to decrease particulate matter in indoor environments. The previous standard in Europe for testing air filters for general ventilation was EN 779. In ...July 2018, it was replaced by the new international standard ISO 16890. One major change is the discharging process: It is now performed by treating the filters with saturated isopropyl alcohol (IPA) vapor. The process is intended to simulate a worst‐case scenario of the filtration efficiency due to the reduction of the electret effect. These minimal efficiencies are a principal part of the filter classification. Therefore, two round robin tests with different filter classes (F9 and F7 according to EN 779) and up to eleven participants were carried out to evaluate the new test method by comparing the filtration efficiencies and pressure drops before and after the IPA treatment. Pressure drop measurements showed no mechanical altering of the material due to the discharging process. The calculated filter classes had a maximum deviation of 5%. Even with different equipment, the results indicate that the new ISO 16890 seems to be a viable test standard and a decent replacement for previous national standards.
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.
The role of bacteria in chronic rhinosinusitis (CRS) is still not well understood. Whole microbiome analysis adds new aspects to our current understanding that is mainly based on isolated bacteria. ...It is still unclear how the results of microbiome analysis and the classical culture based approaches interrelate. To address this, middle meatus swabs and tissue samples were obtained during sinus surgery in 5 patients with CRS with nasal polyps (CRSwNP), 5 patients with diffuse CRS without nasal polyps (CRSsNP), 5 patients with unilateral purulent maxillary CRS (upm CRS) and 3 patients with healthy sinus mucosa. Swabs were cultured, and associated bacteria were identified. Additionally, parts of each tissue sample also underwent culture approaches, and in parallel DNA was extracted for 16S rRNA gene amplicon-based microbiome analysis. From tissue samples 4.2 ± 1.2 distinct species per patient were cultured, from swabs 5.4 ± 1.6. The most frequently cultured species from the swabs were
spp. and
. The 16S-RNA gene analysis revealed no clear differentiation of the bacterial community of healthy compared to CRS samples of unilateral purulent maxillary CRS and CRSwNP. However, the bacterial community of CRSsNP differed significantly from the healthy controls. In the CRSsNP samples
, and
were significantly enriched compared to the healthy controls. Species isolated from culture did not generally correspond with the most abundant genera in microbiome analysis. Only
, and
found in 2 unilateral purulent maxillary CRS samples by the cultivation dependent approach were also found in the cultivation independent approach in high abundance, suggesting a classic infectious pathogenesis of odontogenic origin in these two specific cases. Alterations of the bacterial community might be a more crucial factor for the development of CRSsNP compared to CRSwNP. Further studies are needed to investigate the relation between bacterial community characteristics and the development of CRSsNP.
To assess positioning accuracy in otosurgery and to test the impact of the two-handed instrument holding technique and the instrument support technique on surgical precision. To test an otologic ...training model with optical tracking.
In total, 14 ENT surgeons in the same department with different levels of surgical experience performed static and dynamic tasks with otologic microinstruments under simulated otosurgical conditions.
Tip motion of the microinstrument was registered in three dimensions by optical tracking during 10 different tasks simulating surgical steps such as prosthesis crimping and dissection of the middle ear using formalin-fixed temporal bone. Instrument marker trajectories were compared within groups of experienced and less experienced surgeons performing uncompensated or compensated exercises.
Experienced surgeons have significantly better positioning accuracy than novice ear surgeons in terms of mean displacement values of marker trajectories. The instrument support and the two-handed instrument holding techniques significantly reduce surgeons' tremor. The laboratory set-up presented in this study provides precise feedback for otosurgeons about their surgical skills and proved to be a useful device for otosurgical training.
Simple tremor compensation techniques may offer trainees the potential to improve their positioning accuracy to the level of more experienced surgeons. Training in an experimental otologic environment with optical tracking may aid acquisition of technical skills in middle ear surgery and potentially shorten the learning curve. Thus, simulated exercises of surgical steps should be integrated into the training of otosurgeons.
Air quality measurements usually consist of ground-based instrumentation at fixed locations. However, vertical profiles of pollutants are of interest for understanding processes, distribution, ...dilution and concentration. Therefore, a multicopter system has been developed to investigate the vertical distribution of the concentration of aerosol particles, black carbon, ozone, nitrogen oxides (NOx) and carbon monoxide and the meteorological parameters of temperature and humidity. This article presents the requirements by different users, the setup of the quadrocopter system, the instrumentation and the results of first applications. The vertical distribution of particulate matter next to a highway was strongly related to atmospheric stratification, with different concentrations below and above the temperature inversion present in the morning. After the qualification phase described in this article, two identically equipped multicopters will be used upwind and downwind of line or diffuse sources such as highways or urban areas to quantify the influence of their emissions on the local air quality.
To assess long-term results and present experience with a high-porosity hydroxyapatite ceramic for obliterating large open mastoid cavities.
Cross-sectional cohort study.
Tertiary academic referral ...center.
All patients who underwent tympanomastoid surgery for chronic middle ear disease or revision surgery with reduction of an open mastoid cavity using a highly porous hydroxyapatite matrix material (HMM) between May 2005 and June 2013 were assessed for eligibility. Twenty three patients (56.9 ± 18.3 yr) were included.
Primary middle ear surgery or revision surgery using a HMM.
Pure-tone average, computed tomography (CT), and magnetic resonance imaging (MRI) to investigate osseoinduction, osseointegration and presence of cholesteatoma, current quality of life assessed by Zurich Chronic Middle Ear Inventory and change in quality of life post-intervention assessed by the Glasgow Benefit Inventory.
Patients were reexamined after a mean follow-up period of 88.3 months (SD 21.4 mo) after obliteration of the open mastoid cavity with HMM. Compared with visit 1, patients showed a significantly reduced ABG at visit 2 (29.22 dB ± 2.71 dB versus 12.77 dB ± 3.46 dB).CT scan was carried out in 21 patients (91%) patients and 17 patients (74%) underwent MRI.Revision surgery was required in a total of 17 cases (74%). In four patients recurrent cholesteatoma was found at follow up.
Poor cavity obliteration, a high rate of revision surgery and difficult differentiation between recurrent cholesteatoma and granulation tissue in CT scan was observed.
Zusammenfassung
Hintergrund
Durch die Entwicklung technologischer Innovationen haben sich nicht nur das gesellschaftliche Leben und das Gesundheitssystem verändert, sondern auch die Anforderungen an ...die Lehre. Ziel dieser Pilotstudie war es zu evaluieren, ob Studierende bei der Observation eines mikrochirurgischen Eingriffs am Schläfenbein mit Annotation chirurgischer Landmarken ein zusätzliches Verständnis anatomischer Strukturen erlangen, wenn eine Visualisierung verwendet wird, die für Chirurg und Betrachter gleiche 3‑D-Ansichten bietet.
Material und Methoden
Während regulärer Anwesenheitspraktika wurden Studierende drei Gruppen randomisiert zugewiesen: Kontroll‑, 2‑D‑ oder 3‑D-Gruppe. Mithilfe von Evaluationsbögen/intraoperativer Annotation chirurgischer Landmarken des Operationssitus erfolgte die Beurteilung des subjektiv didaktischen Werts verschiedener Visualisierungsformate und daraus resultierender Lernerfahrungen.
Ergebnisse
47 Studierende konnten in die Studie einbezogen werden. Die Mehrheit der Studierenden gab einen sehr hohen Mehrwert der 3‑D-Visualisierung bezüglich der Methode (70 %) und der Anschaulichkeit (80 %) im Vergleich zur 2‑D‑ und Kontrollgruppe an. 69 % der Studierenden stimmten der Aussage voll und ganz zu, dass die 2‑D- und 3‑D-Visualisierung die Lernmotivation erhöht und sehr gut geeignet ist, Topographie/und Strukturen besser zu erkennen.
Schlussfolgerung
Die Verwendung interaktiver Visualisierungsmöglichkeiten in der Lehre unterstützt die Lerneffizienz und ‑motivation der Studierenden. Besonders die 3‑D-Visualisierung und die intraoperative Annotation des Operationssitus ist ein nützliches Werkzeug in der Lehre und erhöht die Qualität dieser. Sie unterstützt die Wahrnehmung der anatomischen Topographie und ermöglicht eine gezieltere chirurgische Ausbildung.
The development of technological innovations has not only changed social life and the healthcare system, but also affects medical education. The aim of this pilot study was to evaluate whether ...students, when observing a microsurgical procedure of the temporal bone, gain an additional understanding of the anatomical structures and surgical site when visualization is used that provides identical views for the surgeon and viewer in 3D.
During regular attendance tutorials, students were randomly assigned to three different groups: control group, 2D group, or 3D group. Evaluation questionnaires and intraoperative student annotation of the surgical view were used to assess the subjective didactic value of different visualization formats and resultant learning experiences for the students.
A total of 47 students were included in the investigations during conventional attendance tutorials. The majority indicated a high added value of the 3D visualization in terms of method (70%) and vividness (80%) compared to the 2D group and self-study; 69% of the students fully agreed with the statement that 2D and 3D visualization increases learning motivation and is a very good way to improve recognition of anatomical topography and structures.
New interactive visualization options in teaching promote learning efficiency and motivation among students. Especially 3D visualization and intraoperative annotation of the surgical view by the student is a useful didactic tool and increases the quality of clinical teaching. It supports the perception of anatomical topography and enables more focused surgical training.
In this work, we used a Zeppelin NT equipped with six sensor setups, each composed of four different low-cost electrochemical sensors (ECSs) to measure nitrogen oxides (NO and NO2), carbon monoxide, ...and Ox (NO2+O3) in Germany. Additionally, a MIRO MGA laser absorption spectrometer was installed as a reference device for in-flight evaluation of the ECSs. We report not only the influence of temperature on the NO and NO2 sensor outputs but also find a shorter timescale (1 s) dependence of the sensors on the relative humidity gradient. To account for these dependencies, we developed a correction method that is independent of the reference instrument. After applying this correction to all individual sensors, we compare the sensor setups with each other and to the reference device. For the intercomparison of all six setups, we find good agreements with R2≥0.8 but different precisions for each sensor in the range from 1.45 to 6.32 ppb (parts per billion). The comparison to the reference device results in an R2 of 0.88 and a slope of 0.92 for NOx (NO+NO2). Furthermore, the average noise (1σ) of the NO and NO2 sensors reduces significantly from 6.25 and 7.1 to 1.95 and 3.32 ppb, respectively. Finally, we highlight the potential use of ECSs in airborne applications by identifying different pollution sources related to industrial and traffic emissions during multiple commercial and targeted Zeppelin flights in spring 2020. These results are a first milestone towards the quality-assured use of low-cost sensors in airborne settings without a reference device, e.g., on unmanned aerial vehicles (UAVs).
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