Electronic Structure Mapping of Branching States in Poly[methyl(phenyl)silane] Upon Exposure to UV Radiation

Frantiˇsek Schauer,Luk´aˇs Tk´aˇ,Miroslava Oˇzvoldov´,Vojtech Nad´aˇzdy,Katar´ana Gmucov´a,Karol V´egs¨,Miroslava Tk´aˇcov´,Juraj Chlp´ık 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.4

The origin of white photoluminescence in polysilanes has long been disputed, and this emission is closely connected with information recording in nanotechnologies. We elucidated UV degradation of an archetypal model polymer poly[methyl(phenyl)silane] by using a new method for electronic structure mapping of organic semiconductors, energy-resolved electrochemical impedance spectroscopy (ER-EIS) and photoluminescence spectroscopy. UV exposure at 345 nm resulted in two defect bands above the highest occupied molecular orbital (HOMO) in the energy region from −5.5 eV to −3.5 eV with respect to the zero vacuum energy level. The respective density of states was 1016 − 1017 cm−3eV−1, and the total integrated concentration was 0 − 1017 cm−3. The photoluminescence in the long-wavelength region gave wide bands with photon energies from 2.2 eV to 3.2 eV (corresponding to wavelengths from 600 nm to 390 nm). The observed bands were interpreted by assuming the formation of energetically distributed Si branching radiative states, whose distribution in the HOMO − lowest unoccupied molecular orbital (LUMO) gap was observed by using ER-EIS. The quantum efficiency of defect state formation increased from (x)345 nm = 0.0045 to (x)290 nm = 0.053. The obtained results may contribute to the production of effective polysilane nanomasks and to information recording.

Estimating Probability for Esophageal Obstruction: A Diagnostic Decision Support Tool Applying Machine Learning to Functional Lumen Imaging Probe Panometry

Jacob M Schauer,Wenjun Kou,Jacqueline E Prescott,Peter J Kahrilas,John E Pandolfino,Dustin A Carlson 대한소화기 기능성질환∙운동학회 2022 Journal of Neurogastroenterology and Motility (JNM Vol.28 No.4

Background/Aims This study aimed to develop a diagnostic tool using machine learning to apply functional luminal imaging probe (FLIP) panometry data to determine the probability of esophagogastric junction (EGJ) obstruction as determined using the Chicago Classification version 4.0 (CCv4.0) and high-resolution manometry (HRM). Methods Five hundred and fifty-seven adult patients that completed FLIP and HRM (with a conclusive CCv4.0 assessment of EGJ outflow) and 35 asymptomatic volunteers (“controls”) were included. EGJ opening was evaluated with 16-cm FLIP performed during sedated endoscopy via EGJ-distensibility index and maximum EGJ diameter. HRM was classified according to the CCv4.0 as conclusive disorders of EGJ outflow or normal EGJ outflow (timed barium esophagram applied when required and available). The probability tool utilized Bayesian additive regression treesBART, which were evaluated using a leave-one-out approach and a holdout test set. Results Per HRM and CCv4.0, 243 patients had a conclusive disorder of EGJ outflow while 314 patients (and all 35 controls) had normal EGJ outflow. The model accuracy to predict EGJ obstruction (based on leave-one-out/holdout test set, respectively) was 89%/90%, with 87%/85% sensitivity, 92%/97% specificity, and an area under the receiver operating characteristic curve of 0.95/0.97. A free, open-source tool to calculate probability for EGJ obstruction using FLIP metrics is available at https://www.wklytics.com/nmgi/prob_flip.html. Conclusions Application of FLIP metrics utilizing a probabilistic approach incorporates the diagnostic confidence (or uncertainty) into the clinical interpretation of EGJ obstruction. This tool can provide clinical decision support during application of FLIP Panometry for evaluation of esophageal motility disorders.

Fine Particle Air Pollution and Mortality: Importance of Specific Sources and Chemical Species

Heo, Jongbae,Schauer, James J.,Yi, Okhee,Paek, Domyung,Kim, Ho,Yi, Seung-Muk by Lippincott Williams Wilkins, Inc 2014 Epidemiology Vol.25 No.3

BACKGROUND:: While exposure to ambient fine particles <2.5 μm in aerodynamic diameter (PM2.5) has well-established health effects, there is limited quantitative evidence that links specific sources of PM2.5 with those effects. This study was designed to examine the risks of exposure to chemical species and source-specific PM2.5 mass on mortality in Seoul, Korea, a highly populated city. METHODS:: We compare daily mortality counts with PM2.5 chemical speciation data collected every 3 days, as well as nine sources of PM2.5 mass resolved by a positive matrix factorization receptor model, from March 2003 through November 2007. A Poisson generalized linear model incorporating natural splines was used to evaluate associations of PM2.5 chemical species and sources with mortality. RESULTS:: PM2.5 mass and several chemical species were associated with mortality. Organic carbon, elemental carbon, and lead were associated with mortality outcomes when using multipollutant models adjusted for other chemical species levels. Source-apportioned PM2.5 derived from mobile sources (ie, gasoline and diesel emissions) and biomass burning was associated with respiratory mortality and cardiovascular mortality, respectively. There were moderate associations of industry and of roadway emissions with cardiovascular mortality. CONCLUSIONS:: Local combustion sources may be particularly important contributors to PM2.5, leading to adverse health effects.

Chemical Characteristics of Size-Resolved Aerosols in Coastal Areas during KORUS-AQ Campaign; Comparison of Ion Neutralization Model

배민석,이태형,James J. Schauer,박규태,손영백,김기현,Seung-Sik Cho,Seung Shik Park,박기홍,Zang-HoShon 한국기상학회 2019 Asia-Pacific Journal of Atmospheric Sciences Vol.55 No.3

Measurements for size-resolved chemical composition were made at the Anmyeon Island station on the western coast of the Republic of Korea between May 28 and June 20, 2016. This study determined the main chemical compositions of size-resolved particulate matter (i.e., organic carbon, elemental carbon, water-soluble organic carbon, water-soluble ions, and benzene carboxylic acids) from a total of eight chemically size-resolved sets using micro-orifice uniform deposit impactors. The sum of the species presents a prominent accumulation mode peak at a diameter of 0.56 μm without the coarse mode peak. In the accumulation mode, SO4 2− (49.3%) was the dominant particle component in the size range of 0.1–1.8 μm. Organic carbon and elemental carbon accounted for 13.5% and 0.4%, respectively. Benzene carboxylic acids indicate the accumulation mode peak at the diameter of 0.56 μm. The size-resolved equivalent ion concentration ratios between all measured cations and anions and the ion neutralization model, which uses four major ions, were compared. As a result, the concentration of Na+ is of importance in the accumulation mode for the equivalent ion concentration.

Relationship between reactive oxygen species and water-soluble organic compounds: Time-resolved benzene carboxylic acids measurement in the coastal area during the KORUS-AQ campaign

Bae, Min-Suk,Schauer, James J.,Lee, Taehyoung,Jeong, Ju-Hee,Kim, Yoo-Keun,Ro, Chul-Un,Song, Sang-Keun,Shon, Zang-Ho Elsevier 2017 Environmental pollution Vol.231 No.1

<P><B>Abstract</B></P> <P>This study investigated the relationship between water-soluble organic compounds of ambient particulate matter (PM) and cellular redox activity collected from May 28 to June 20 of 2016 at the west coastal site in the Republic of Korea during the KORea-US Air Quality (KORUS-AQ) campaign. Automatic four-hour integrated samples operated at a flow rate of 92 L per minute for the analysis of organic carbon (OC), water-soluble organic carbon (WSOC), elemental carbon (EC), water-soluble ions (WSIs), and benzene carboxylic acids (BCAs) were collected on a 47 mm quartz fiber filter. The influence of atmospheric transport processes was assessed by the Weather Research and Forecasting (WRF) model. OC, EC, WSOC, and BCA were determined by SUNET carbon analyzer, total organic carbon (TOC) analyzer, and liquid chromatography-mass spectrometry mass spectrometry (LC-MSMS), respectively. Twenty-four-hour integrated samples were collected for reactive oxygen species (ROS) analysis using a fluorogenic cell-based method to investigate the main chemical classes of toxicity. The results illustrate that WSOC and specific water-soluble species are associated with the oxidative potential of particulate matter. Pairwise correlation scatterplots between the daily-averaged WSOC and ROS (r<SUP>2</SUP> of 0.81), and 135-BCA and ROS (r<SUP>2</SUP> of 0.84), indicate that secondary organic aerosol production was highly associated with ROS activity. In addition, X-ray spectral analysis together with secondary electron images (SEIs) of PM<SUB>2.5</SUB> particles collected during high ROS concentration events clearly indicate that water-soluble organic aerosols are major contributors to PM<SUB>2.5</SUB> mass. This study provides insight into the components of particulate matter that are drivers of the oxidative potential of atmospheric particulate matter and potential tracers for this activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sensitive Analysis of Underivatized Benzene Carboxylic Acids using Time-resolved PM2.5 Sequence Sampling. </LI> <LI> Toxicity intensities between reactive oxygen species and water-soluble compounds. </LI> <LI> Good coefficients of determination between reactive oxygen species and carboxylic acids. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Relationship between Reactive Oxygen Species and Benzene Carboxylic Acids Using LC/MSMS at the Anmyeon Site

배민석,James J. Schauer,이태형,정주희,김유근,노철언,송상근,손장호 한국대기환경학회 2017 한국대기환경학회 학술대회논문집 Vol.2017 No.11

Influence of Hydrophilic and Hydrophobic Water-soluble Organic Carbon Fractions on Light Extinction at an Urban Site

박승식,김경원,James J. Schauer 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.10

Until now, quantitative contributions of hydrophilic and hydrophobic water-soluble organic carbon (WSOC) fractions to aerosol light extinction have not been studied. In this study, concentrations of chemical species in PM2.5 (particulate matter with diameters less than 2.5 μm), including elemental carbon (EC), organic carbon (OC), total WSOC, two fractionated WSOCs, water-soluble inorganic species, and metal species, were measured twice a day between December 27, 2010 and January 20, 2011, at an urban site in Seoul, Korea. A macro-porous XAD7HP resin column was used to separate the liquid extracts into hydrophilic and hydrophobic WSOC (WSOCHPI and WSOCHPO) fractions. Water-insoluble OC (WIOC), WSOCHPI and WSOCHPO were used to estimate the aerosol light extinction from the original IMPROVE algorithm. Organic mass to organic carbon (OM/OC) ratios of 1.6, 2.0, and 1.8 were applied to the WIOC, WSOCHPI , and WSOCHPO, respectively. Light extinctions for ammonium sulfate, ammonium nitrate, POM (particulate organic matter = WIOM + WSOMHPI + WSOMHPO), and EC (which is light absorbing) were determined as 38.9 ± 34.0, 64.7 ± 70.6, 69.5 ± 27.7, and 27.1 ± 11.0 Mm^-1, respectively, and contributed 15.0% (range: 5.4 - 25.6), 22.2% (7.1 - 50.8), 30.8% (13.0 - 42.3) and 12.0% (5.1 - 21.3), respectively, to the total light extinction budgets. Light scattering due to the WIOM, WSOMHPI and WSOMHPO were 27.3 ± 13.1, 17.1 ± 8.7, and 24.1 ± 9.9 Mm^-1, respectively, and accounted for 12.5, 7.5, and 10.7% of the total light extinction budget. The results indicate WSOCHPO has a greater impact on visibility reduction in wintertime than WSOCHPI at this site. Light scattering by total OC concentration (POM=1.6 × OC) was 62.2 ± 25.1 Mm^-1, which was approximately 9.7% lower than the sum of light scattering due to each of the three OC components with different OM/OC ratios. As the relative humidity (RH) increased, light extinction was higher in the water-soluble inorganic components ((NH₄)₂SO₄ and NH₄NO3) than in the water-soluble organic fractions. In the IMPROVE algorithm, the hygroscopic growth factor for POM was assumed to be 1 (non-hygroscopic) due to a lack of evidence for water growth by ambient POM. However, the relationships between the RH and light scattering due to WSOMHPI (R²=0.49) and WSOMHPO (R² = 0.31) suggest that different hygroscopic growth factors should be applied to the hydrophilic and the hydrophobic WSOC fractions. Consequently, additional experimental work is needed to explore hygroscopic growth curves for the two fractionated WSOC components.

항공 요구조건에 따른 TruPrint 5000 에 대한 Ti6Al4V의 기계적 특성 평가

Simone Koummarasy,Jan Christian Schauer,Matthias Mueller 한국레이저가공학회 2021 Laser Solutions Vol.24 No.10

본 보고서는 Toolcraft와 TRUMPF가 TRUMPF에서 출시한 최신 설비 중 하나인 TruPrint 5000에서 Ti6Al4V시편의 초기 검증에 어떻게 접근했는지에 대한 방법을 소개하는 내용으로 구성되어 있다. Laser Powder Bed Fusion (LPBF) 기술을 사용하여 적층 제조된 부품에 대한 항공 요구 사항에 따라 Toolcraft에서 산업용 항공 우주 환경 내 TruPrint 5000에서 테스트 빌드 작업을 설계 및 생산했다. 본 자료의 주 내용인 재료 특성 관련 결과(CT 촬영, 미세구조 및 입자 크기, 인장시험, 피로시험, 파괴인성 등)는 정식 인가를 보유한 외부 시험 기관을 통하여 평가 및 확인하였다.

Visualization of Candidate Division OP3 Cocci in Limonene-Degrading Methanogenic Cultures

( Amelia Elena Rotaru ),( Regina Schauer ),( Christina Probian ),( Marc Mussmann ),( Jens Harder ) 한국미생물 · 생명공학회 2012 Journal of microbiology and biotechnology Vol.22 No.4

Members of candidate division OP3 were detected in 16S rRNA gene clone libraries from methanogenic enrichment cultures that utilized limonene as a carbon and energy source. We developed probes for the visualization of OP3 cells. In situ hybridization experiments with newly designed OP3-specific probes [OP3-565 and Eub-338(VI)] revealed abundant small OP3 cocci attached to larger cells. Syntrophic Deltaproteobacteria, OP3 cells, and methanogens affiliating with Methanoculleus and Methanosaeta formed the limonenedegrading community.

EEG-based BCI for the linear control of an upper-limb neuroprosthesis

Vidaurre, C.,Klauer, C.,Schauer, T.,Ramos-Murguialday, A.,Muller, K.R. Butterworth-Heinemann 2016 Medical engineering & physics Vol.38 No.11

Assistive technologies help patients to reacquire interacting capabilities with the environment and improve their quality of life. In this manuscript we present a feasibility study in which healthy users were able to use a non-invasive Motor Imagery (MI)-based brain computer interface (BCI) to achieve linear control of an upper-limb functional electrical stimulation (FES) controlled neuro-prosthesis. The linear control allowed the real-time computation of a continuous control signal that was used by the FES system to physically set the stimulation parameters to control the upper-limb position. Even if the nature of the task makes the operation very challenging, the participants achieved a mean selection accuracy of 82.5% in a target selection experiment. An analysis of limb kinematics as well as the positioning precision was performed, showing the viability of using a BCI-FES system to control upper-limb reaching movements. The results of this study constitute an accurate use of an online non-invasive BCI to operate a FES-neuroprosthesis setting a step toward the recovery of the control of an impaired limb with the sole use of brain activity.