Nitrate formation mechanisms causing high concentration of PM2.5 in a residential city with low anthropogenic emissions during cold season.

During the cold season in South Korea, NO3- concentrations are known to significantly increase, often causing PM2.5 to exceed air quality standards. This study investigated the formation mechanisms of NO3- in a suburban area with low anthropogenic emissions. The average PM2.5 was 25.3 µg m-3, with NO3- identified as the largest contributor. Ammonium-rich conditions prevailed throughout the study period, coupled with low atmospheric temperature facilitating the transfer of gaseous HNO3 into the particulate phase. This result indicates that the formation of HNO3 played a crucial role in determining particulate NO3- concentration. Nocturnal increases in NO3- were observed alongside increasing ozone (O3) and relative humidity (RH), emphasizing the significance of heterogeneous reactions involving N2O5. NO3- concentrations at the study site were notably higher than in Seoul, the upwind metropolitan area, during a high concentration episode. This difference could potentially attributed to lower local NO concentrations, which enhanced the reaction between O3 and NO2, to produce NO3 radicals. High concentrations of Cl- and dust were also identified as contributors to the elevated NO3- concentrations.

Optimizing an airborne mass-balance methodology for accurate emission rate quantification of industrial facilities: A case study of industrial facilities in South Korea.

Accurate estimation of emissions from industrial point sources is crucial in understanding the effectiveness of reduction efforts and establishing reliable emission inventories. In this study, we employ an airborne Chemical Ionization Mass Spectrometry (CIMS) instrument to quantify sulfur dioxide (SO2) emissions from prominent industrial facilities in South Korea, including power plants, a steel mill, and a petrochemical facility. Our analysis utilizes the box mass balance technique to derive SO2 emissions and associated uncertainty. We evaluate the interpolation methods between 2D kriging and 3D radial basis function. The results demonstrate that the total uncertainty of the box mass balance technique ranges from 5 % to 28 %, with an average of 20 %. Mixing ratio ground extrapolation from the lowest altitude of the airborne sampling to the ground emerges as the dominant source of uncertainty, followed by the determination of the boundary layer height. Adequate sampling at multiple altitudes is found to be essential in reducing the overall uncertainty by capturing the full extent of the plume. Furthermore, we assess the uncertainty of the single-height transect mass balance method commonly employed in previous studies. Our findings reveal an average precision of 47 % for this method, with the potential for overestimating emissions by up to 206 %. Samplings at fewer altitudes or with larger altitude gaps increase the risk of under-sampling and elevate method uncertainties. Therefore, this study provides a quantitative basis to evaluate previously airborne observational emission constraints.

Airborne estimation of SO2 emissions rates from a coal-fired power plant using two top-down methods: A mass balance model and Gaussian footprint approach.

In this study, two top-down methods-mass balance and Gaussian footprint-were used to determine SO2 emissions rates via three airborne sampling studies over Korea's largest coal power plant in October 2019 and 2020. During the first two flights in October 2019, mass balance approaches significantly underestimated the SO2 emissions rates by 75 % and 28 %, respectively, as obtained from the real-time stack monitoring system. Notably, this large discrepancy accounted for the insufficient number of transects altitudes and high levels of background SO2 along the upwind side. Alternatively, the estimated SO2 emissions rates of the third flight (October 2020) displayed a difference of <10 % from rea-time monitoring data (630 vs. 690 kg·hr-1), owing to the enhanced vertical resolution with increased transects and lower background SO2 levels. In contrast to the mass balance method, Gaussian footprints offered significantly improved accuracy (relative error: 41 %, 32 %, and 2 % for Flights 1, 2, and 3, respectively). This relatively good performance was attributed to prior emissions knowledge via the Clean Air Policy Support System (CAPSS) emissions inventory and its unique ability to accurately estimate stack-level SO2 emissions rates. Theoretically, the Gaussian footprint was less prone to sparse transects and upwind background levels. However, it can be substantially influenced by atmospheric stability and consequently by effective stack heights and dispersion parameters; basically, all factors with minimal-to-no influence on the mass balance approach. Conversely, the mass balance method was the only plausible approach to estimate unidentified source emissions rates when well-defined prior emission information was unknown. Here, the footprint approach supplemented the mass balance method when the emission inventories were known, and employing both strategies approaches greatly enhanced the integrity of top-down emissions inventories from the power plant sources, thus, supporting their potential for ensuring operational compliance with SO2 emissions regulation.

A Novel Expert Coaching Model in Urology, Aimed at Accelerating the Learning Curve in Robotic Prostatectomy.

INTRODUCTION/BACKGROUND: The surgical residency model assumes that upon completion, a surgeon is ready to practice and grow independently. However, many surgeons fail to improve after reaching proficiency, which in certain instances has correlated with worse clinical outcomes. Coaching addresses this problem and furthers surgeons' education post-residency. Currently, surgical coaching programs focus on medical students and residents, and have been shown to improve residents' and medical students' technical and non-technical abilities. Coaching programs also increase the accuracy of residents, fellows, and attendings in self-assessing their surgical ability. Despite the potential benefits, coaching remains underutilized and poorly studied. We developed an expert-led, face-to-face, video-based surgical coaching program at a tertiary medical center among specialized attending surgeons. Our goal was to evaluate the feasibility of such a program, measure surgeons' attitudes towards internal peer coaching, determine whether surgeons found the sessions valuable and educational, and to subjectively self-assess changes in operative technique. METHODS/MATERIALS: Surgeons who perform robot-assisted laparoscopic prostatectomies were chosen and grouped by number of cases completed: junior (<100 cases), intermediate (100-500 cases), and senior (>500 cases). Surgeons were scheduled for 3 1-hour coaching sessions 1-2 months apart (February-October 2019), meeting individually with the coach (PS), an expert Urologic Oncologist with thousands of cases of experience performing radical prostatectomy. He received training on coaching methodology prior to beginning the coaching program. Before each session, surgeons selected 1 of their recent intraoperative videos to review. During sessions, the coach led discussion on topics chosen by the surgeon (i.e. neurovascular bundle dissection, apical dissection, bladder neck); together, they developed goals to achieve before the next session. Subsequent sessions included presentation and discussion of a case occurring subsequent to the prior session. Sessions were coded by discussion topics and analyzed based on level of experience. Surgeons completed a survey evaluating the experience. RESULTS: All 6 surgeons completed 3 sessions. Five surgeons completed the survey; most respondents evaluated themselves as having improved in desired areas and feeling more confident performing the discussed steps of the operation. Discussed surgical principles varied by experience group; when subjectively quantifying the difficulty of surgical steps, the more difficult steps were discussed by the higher experience groups compared to the junior surgeons. The senior surgeons also focused more on oncologic potency, continence outcomes, and more theory-driven questions while the junior surgeons tended to focus more on anatomic and technique-based questions such as tissue handling and the use of cautery and clips. Overall, the surgeons thought this program provoked critical discussion and subsequently modified their technique, and "agreed" or "strongly agreed" that they would seek further sessions. CONCLUSIONS: Surgical coaching at a large medical center is not only feasible but was rated positively by surgeons across all levels of experience. Coaching led to subjective self-improvement and increased self-confidence among most surgeons. Surgeons also felt that this program offered a safe space to acquire new skills and think critically after finishing residency/fellowship. Themes discussed and takeaways from the sessions varied based on surgeon experience level. While further research is needed to more objectively quantify the impact coaching has on surgeon metrics and patient outcomes, the results of this study supports the initial "proof-of-concept" of peer-based surgical coaching and its potential benefits in accelerating the learning curve for surgeons' post-residency.

The Korea-United States Air Quality (KORUS-AQ) field study.

The Korea-United States Air Quality (KORUS-AQ) field study was conducted during May-June 2016. The effort was jointly sponsored by the National Institute of Environmental Research of South Korea and the National Aeronautics and Space Administration of the United States. KORUS-AQ offered an unprecedented, multi-perspective view of air quality conditions in South Korea by employing observations from three aircraft, an extensive ground-based network, and three ships along with an array of air quality forecast models. Information gathered during the study is contributing to an improved understanding of the factors controlling air quality in South Korea. The study also provided a valuable test bed for future air quality-observing strategies involving geostationary satellite instruments being launched by both countries to examine air quality throughout the day over Asia and North America. This article presents details on the KORUS-AQ observational assets, study execution, data products, and air quality conditions observed during the study. High-level findings from companion papers in this special issue are also summarized and discussed in relation to the factors controlling fine particle and ozone pollution, current emissions and source apportionment, and expectations for the role of satellite observations in the future. Resulting policy recommendations and advice regarding plans going forward are summarized. These results provide an important update to early feedback previously provided in a Rapid Science Synthesis Report produced for South Korean policy makers in 2017 and form the basis for the Final Science Synthesis Report delivered in 2020.

Primary and secondary aerosols in small passenger vehicle emissions: Evaluation of engine technology, driving conditions, and regulatory standards.

The characteristics of primary gas/aerosol and secondary aerosol emissions were identified for small passenger vehicles using typical fuel types in South Korea (gasoline, liquefied petroleum gas (LPG), and diesel). The generation of secondary organic aerosol (SOA) was explored using the potential aerosol mass (PAM) oxidation flow reactor. The primary emissions did not vary significantly between fuel types, combustion technologies, or aftertreatment systems, while the amount of NH3 was higher in gasoline and LPG vehicle emissions than that in diesel vehicle emissions. The SOA emission factor was 11.7-66 mg kg-fuel-1 for gasoline vehicles, 2.4-50 mg kg-fuel-1 for non-diesel particulate filter (non-DPF) diesel vehicles (EURO 2-3), 0.4-40 mg kg-fuel-1 for DPF diesel vehicles (EURO 4-6), and 3-11 mg kg-fuel-1 for LPG vehicles (lowest). The carbonaceous aerosols (equivalent black carbon (eBC) + primary organic aerosol + SOA) of diesel vehicles in EURO 4-6 were reduced by up to 95% compared to those in EURO 2-3. The expected SOA yield increased through the hot-condition combustion section of a vehicle, over the SOA range of 0.2-155 µg m-3. These results provide the necessary data to analyze all types of SOA generated by the gas-phase oxidation in vehicle emissions in metropolitan areas.

Defining the index lesion for potential salvage partial or hemi-gland ablation after radiation therapy for localized prostate cancer.

BACKGROUND: Salvage partial gland ablation (sPGA) has been proposed to treat some localized radiorecurrent prostate cancer. The role of prostate biopsy and magnetic resonance imaging (MRI) characteristics to identify patients eligible for sPGA is unknown. OBJECTIVE: To evaluate the ability of MRI and prostate biopsy characteristics to identify an index lesion suitable for sPGA and validate this selection using detailed tumor maps created from whole-mount slides from salvage radical prostatectomy (sRP) specimens. DESIGN, SETTING, AND PARTICIPANTS: Men who underwent sRP for recurrent prostate cancer following primary radiotherapy with external beam radiotherapy (EBRT) and/or brachytherapy between 2000 and 2014 at a single high-volume cancer center were eligible. Those with tumor maps, MRI and biopsy data were included in analysis. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Primary outcome was the ability of clinicopathologic and imaging criteria to identify patients who may be eligible for sPGA based on detailed tumor map from whole-mount sRP slides. RESULTS AND LIMITATIONS: Of 216 men who underwent sRP following whole gland radiotherapy, tumor maps, MRI, and biopsy data were available for 77. Of these, 15 (19%) were determined to be eligible for sPGA based on biopsy-proven unilateral disease in contiguous sextant segments, a dominant lesion on MRI concordant with biopsy location or no focal region of interest, and no imaging evidence of extraprostatic disease. Review of tumor maps identified 6 additional men who would have met criteria for sPGA, resulting in sensitivity of 71% (95% C.I. 48%-89%) and specificity of 100% (lower bound of 95% C.I. 94%). None of the 15 men who met the criteria for sPGA on clinical data were identified incorrectly on tumor maps to require full gland surgery (upper bound of 95% C.I. 22%). Median tumor volume of the index lesion was 0.4 cc and recurrent cancer was noted in the apex, mid-gland, and base in 81%, 100%, and 29% of men. CONCLUSIONS: In men with recurrent prostate cancer after radiotherapy, biopsy findings and MRI can be used to select index lesions potentially amenable for sPGA and can guide patient evaluation for inclusion in clinical trials of sPGA following radiation failure. Larger, prospective studies are required to evaluate both the role of MRI and clinical criteria in guiding focal salvage therapy and the effectiveness of this modality for radiorecurrent prostate cancer.

A systematic review of outcomes after thermal and nonthermal partial prostate ablation.

We sought to compare oncologic and functional outcomes between thermal and nonthermal energy partial gland ablation (PGA) modalities. We conducted comprehensive, structured literature searches, and 39 papers, abstracts, and presentations met the inclusion criteria of pre-PGA magnetic resonance imaging, oncologic outcomes of at least 6 months, and systematic biopsies after PGA. Twenty-six studies used thermal ablation: high-intensity focused ultrasound (HIFU), cryotherapy, focal laser ablation, or radiofrequency ablation. In-field recurrence rates ranged from 0 to 36% for HIFU, 6 to 24% for cryotherapy, 4 to 50% for focal laser ablation, and 20 to 25% for radiofrequency ablation. Twelve studies used nonthermal technologies of focal brachytherapy, vascular-targeted photodynamic therapy, or irreversible electroporation. Focal brachytherapy had the lowest reported failure rate of 8%, vascular-targeted photodynamic therapy had >30% positive in-field biopsies, and irreversible electroporation had in-field recurrence rates of 12-35%. PGA was well tolerated, and nearly all patients returned to baseline urinary function 12 months later. Most modalities caused transient decreases in erectile function. Persistent erectile dysfunction was highest in patients who underwent HIFU. Although oncologic outcomes vary between treatment modalities, systematic review of existing data demonstrates that PGA is a safe treatment option for patients with localized prostate cancer.

Boundary layer versus free tropospheric submicron particle formation: A case study from NASA DC-8 observations in the Asian continental outflow during the KORUS-AQ campaign.

In this study, we contrasted major secondary inorganic species and processes responsible for submicron particle formation (SPF) events in the boundary layer (BL) and free troposphere (FT) over the Korean Peninsula during Korea-United States Air Quality (KORUS-AQ) campaign (May-June, 2016) using aircraft observations. The number concentration of ultrafine particles with diameters between 3 nm and 10 nm (NCN3-10) during the entire KORUS-AQ period reached a peak (7,606 ± 12,003 cm -3) at below 1 km altitude, implying that the particle formation around the Korean Peninsula primarily occurred in the daytime BL. During the BL SPF case (7 May, 2016), the SPF over Seoul metropolitan area was more attributable to oxidation of NO2 rather than SO2-to-sulfate conversion. From the analysis of the relationship between nitrogen oxidation ratio (NOR) and temperature or relative humidity (RH), NOR showed a positive correlation only with temperature. This suggests that homogeneous gas-phase reactions of NO2 with OH or O3 contributed to nitrate formation. From the relationship between NCN3-10 (> 10,000 cm-3) and the NOR (or sulfur oxidation ratio) at Olympic Park in Seoul during the entire KORUS-AQ period, it was regarded that the relative importance of nitrogen oxidation was grown as the NCN3-10 increased. During the FT SPF case (31 May, 2016) over the yellow sea, the SO2-to-sulfate conversion seemed to influence SPF highly. The sulfate/CO ratio had a positive correlation with both the temperature and RH, suggesting that aqueous-phase pathways as well as gas-phase reactions might be attributable to sulfate formation in the FT. In particular, FT SPF event on 31 May was possibly caused by the direct transport of SO2 precursors from the continent above the shallow marine boundary layer under favorable conditions for FT SPF events, such as decreased aerosol surface area and increased solar radiation.

Investigation of factors controlling PM2.5 variability across the South Korean Peninsula during KORUS-AQ.

The Korea - United States Air Quality Study (May - June 2016) deployed instrumented aircraft and ground-based measurements to elucidate causes of poor air quality related to high ozone and aerosol concentrations in South Korea. This work synthesizes data pertaining to aerosols (specifically, particulate matter with aerodynamic diameters <2.5 micrometers, PM2.5) and conditions leading to violations of South Korean air quality standards (24-hr mean PM2.5 < 35 µg m-3). PM2.5 variability from AirKorea monitors across South Korea is evaluated. Detailed data from the Seoul vicinity are used to interpret factors that contribute to elevated PM2.5. The interplay between meteorology and surface aerosols, contrasting synoptic-scale behavior vs. local influences, is presented. Transboundary transport from upwind sources, vertical mixing and containment of aerosols, and local production of secondary aerosols are discussed. Two meteorological periods are probed for drivers of elevated PM2.5. Clear, dry conditions, with limited transport (Stagnant period), promoted photochemical production of secondary organic aerosol from locally emitted precursors. Cloudy humid conditions fostered rapid heterogeneous secondary inorganic aerosol production from local and transported emissions (Transport/Haze period), likely driven by a positive feedback mechanism where water uptake by aerosols increased gas-to-particle partitioning that increased water uptake. Further, clouds reduced solar insolation, suppressing mixing, exacerbating PM2.5 accumulation in a shallow boundary layer. The combination of factors contributing to enhanced PM2.5 is challenging to model, complicating quantification of contributions to PM2.5 from local versus upwind precursors and production. We recommend co-locating additional continuous measurements at a few AirKorea sites across South Korea to help resolve this and other outstanding questions: carbon monoxide/carbon dioxide (transboundary transport tracer), boundary layer height (surface PM2.5 mixing depth), and aerosol composition with aerosol liquid water (meteorologically-dependent secondary production). These data would aid future research to refine emissions targets to further improve South Korean PM2.5 air quality.

Quality improvement initiative to reduce variability and improve stewardship of antimicrobial prophylaxis for transrectal prostate needle biopsy.

PURPOSE: To assess the impact of implementing the recommendations included in the 2014 American Urological Association (AUA) white paper on complications of transrectal prostate needle biopsy (PNB). METHODS: In the outpatient setting of a single tertiary-care institution, prophylactic antibiotic use and rate of infectious complications were compared before and after implementation by nursing of a standardized algorithm to select antibiotic prophylaxis (derived from the recommendations of the AUA white paper). The 584 patients in cohort A (January 2011-January 2012) received antimicrobial prophylaxis at the discretion of the treating physician; 654 patients in cohort B (January 2014-January 2015) received standardized risk-adapted antibiotic prophylaxis. Data on antibiotics administered and infectious complications were analyzed. RESULTS: Fluoroquinolone was the most common prophylactic regimen in both cohorts. In cohort A, 73% of men received a single-drug regimen, although 19 different regimens were utilized with duration of 72 h. In cohort B, 97% received 1 of 4 standardized single-drug antibiotic regimens for duration of 24 h. Infectious complications occurred in 19 men (3.3%) in cohort A, and in 18 men (2.8%) in cohort B (difference - 0.5%; one-sided 95% CI 1.1%). No clinically relevant increase in infectious complication rates was found after implementing this quality improvement initiative. CONCLUSIONS: Use of a standardized risk-adapted approach to select antibiotic prophylaxis for PNB by nursing staff reduced the duration of antimicrobial prophylaxis and number of antibiotic regimens used, without increasing the rate of infectious complications. Our findings validate the current AUA recommendations for antibiotic prophylaxis.

Patient-reported pain, discomfort, and anxiety during magnetic resonance imaging-targeted prostate biopsy.

INTRODUCTION: The addition of targeted prostate biopsy to systemic biopsy impacts patient experience. We examined patient-reported pain, discomfort, anxiety, and tolerability among men undergoing magnetic resonance imaging (MRI)-targeted prostate biopsy in addition to transrectal ultrasound-guided systematic biopsy compared to those undergoing systematic biopsy alone. METHODS: All patients underwent transrectal systematic 14-core biopsies. Patients with regions of interest on MRI underwent additional targeted biopsies. All patients received equivalent periprostatic nerve block. Four single-item, standard, 11-point numerical rating scales evaluating pain, discomfort, anxiety, and tolerability were completed immediately after biopsy. Differences in means were compared using t-tests. Correlation between rated domains was tested using Spearman's correlation coefficient. RESULTS: Of 273 consecutive patients, 195 (71%) underwent targeted biopsy and 188 (69%) had undergone prior biopsy. In all men, the median score for pain and tolerability was 3, while the median score for discomfort and anxiety was 4. Pain was rated at 7 or above by 15% of patients. Moderate correlation between pain, discomfort, anxiety, and tolerability of repeat biopsy was observed (Spearman's ρ between 0.48 and 0.76). Compared to patients undergoing systematic biopsy alone, men who received both targeted and systematic biopsies reported higher anxiety scores (difference 1.2; 95% confidence interval [CI] 0.4-2.0; p=0.004) and discomfort (difference 1.0; 95% CI 0.3-1.7; p<0.001). CONCLUSIONS: Patients undergoing targeted and systematic biopsies report more discomfort and anxiety than patients undergoing systematic biopsies alone. Absolute differences are small, and patients are willing to undergo repeat biopsy if advised. Interventions to reduce biopsy-related anxiety are needed.

Role of Changes in Magnetic Resonance Imaging or Clinical Stage in Evaluation of Disease Progression for Men with Prostate Cancer on Active Surveillance.

BACKGROUND: Active surveillance (AS) protocols rely on rectal examination, prostate-specific antigen, imaging, and biopsy to identify disease progression. OBJECTIVE: To evaluate whether an AS regimen based on magnetic resonance imaging (MRI) or clinical stage changes can detect reclassification to grade group (GG) ≥2 disease compared with scheduled systematic biopsies. DESIGN, SETTING, AND PARTICIPANTS: We identified a cohort of men initiated on AS between January 2013 and April 2016 at a single tertiary-care center. Patients completed confirmatory testing and prostate MRI prior to enrollment, then underwent laboratory and physical evaluation every 6 mo, MRI every 18 mo, and biopsy every 3yr. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: MRI results were evaluated using composite Likert/Prostate Imaging Reporting and Data System v2 scoring. MRI and clinical changes were assessed for association with disease progression. Univariable and multivariable regression models were used to predict upgrading on 3-yr biopsy. RESULTS AND LIMITATIONS: At 3yr, of 207 men, 66 (32%) had≥GG2 at biopsy: 55 (83%) with GG2, 10 (15%) with GG3, and one (1.5%) with GG4. Among patients with a 3-yr MRI score of ≥3, 41% had≥GG2 disease, compared with 15% with an MRI score of <3 (p=0.0002). The MRI score increased in 48 men (23%), decreased in 27 (13%), and was unchanged in 132 (64%) men. Increases in MRI score were not associated with reclassification after adjusting for the 3-yr MRI score (p=0.9). Biopsying only for an increased MRI score or clinical stage would avoid 681 biopsies per 1000 men, at the cost of missing ≥GG2 disease in 169 patients. CONCLUSIONS: An AS strategy that uses MRI or clinical changes to trigger prostate biopsy avoids many biopsies but misses an unacceptable amount of clinically significant disease. Prostate biopsy for men on AS should be performed at scheduled intervals, regardless of stable imaging or examination findings. PATIENT SUMMARY: An active surveillance strategy for biopsy based only on increases in magnetic resonance imaging score or clinical stage will avoid many biopsies; however, it will miss many patients with clinically significant prostate cancer.

Case: Spontaneous regression of post-radical prostatectomy prostate-specific antigen elevation without adjuvant therapy in a patient with lymph node metastasis.

Prostate cancer remains the most frequently diagnosed cancer among men. The combination of clinical stage, serum prostate-specific antigen (PSA), and Gleason score (biopsy) assists in predictive assessment of pathological stage and prognosis. Furthermore, pathological criteria, including Gleason score, surgical margin status, extracapsular extension, seminal vesicle invasion, and lymph node involvement, provide prognostication in patients undergoing radical prostatectomy (RP). In this paper, we present a case of a patient with high-risk prostate cancer with persistent PSA elevation post-RP who experiences a complete regression of PSA without any adjuvant therapy. To the authors' knowledge, such a finding has not been described in the literature previously.

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.

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 (r2 of 0.81), and 135-BCA and ROS (r2 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 PM2.5 particles collected during high ROS concentration events clearly indicate that water-soluble organic aerosols are major contributors to PM2.5 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.

Magnetically separable sulfur-doped SnFe2O4/graphene nanohybrids for effective photocatalytic purification of wastewater under visible light.

In this report, magnetically recoverable sulfur-doped SnFe2O4/graphene (S-SFO/GR) nanohybrids have been successfully developed via a facile solvothermal method. The characterizations on the structural, morphology, and optical properties of the nanohybrids indicate that S-SFO particles are successfully embedded on the GR nanosheets. The photocatalytic activity has been evaluated by photocatalytic degradation of chlorotetracycline under visible light irradiation. Among the composites with various mass ratios, the quasi-first-order rate constant of the nanohybrids formed with 9wt% S in SFO and 15wt% GR (9S-SFO/GR-15) can reach as high as 1.83min-1, which is much higher than that of SFO (0.68min-1) and SFO/GR (0.91min-1), confirming the important role of S and GR for the photocatalytic process. The combination of the three components of S, SFO, and GR has enhanced the visible light absorption capability and inhibited the recombination of photogenerated electron-hole. The 9S-SFO/GR-15 nanohybrids can be recovered easily by a magnet and reused for five times with remained photocatalytic efficiency about 70%. A possible catalytic mechanism explaining the efficient photocatalytic performances of the prepared nanohybrids has been proposed.

Utility of preoperative 3 Tesla pelvic phased-array multiparametric magnetic resonance imaging in prediction of extracapsular extension and seminal vesicle invasion of prostate cancer and its impact on surgical margin status: Experience at a Canadian academic tertiary care centre.

INTRODUCTION: To evaluate the utility of 3 Tesla (3T) pelvic phased-array (PPA) multiparametric magnetic resonance imaging (mpMRI) to predict extracapsular extension (ECE) and seminal vesicle invasion (SVI) and its subsequent effect on radical prostatectomy (RP) surgical margin status. METHODS: A retrospective evaluation was conducted of RP patients who underwent preoperative 3T PPA mpMRI (without endorectal coil) based on clinical probability of adverse pathological features. Frequencies, specificity, sensitivity, positive predictive value (PPV), and negative predictive value (NPV) of mpMRI in predicting the status of ECE and SVI were calculated. RESULTS: Forty-eight consecutive patients were included. Sensitivity, specificity, PPV, and NPV for 3T PPA mpMRI using T2-weighted sequences with diffusion-weighted imaging (DWI) and dynamic contrast enhanced (DCE) imaging to predict ECE was 39%, 56%, 45%, and 50%, respectively, while SVI prediction was 33%, 95%, 50%, and 91%, respectively. Twelve of the 28 cases predicted as being negative for ECE had positive margins, while two of the 20 cases predicted to be positive for ECE had positive margins. Imaging predicted four cases would have SVI, yet two had positive margins, while of the 44 cases predicted as being negative for SVI, four had positive margins. CONCLUSIONS: These findings at our centre suggest that the use of 3T PPA mpMRI using T2-weighted sequences with DWI and DCE in predicting pathological ECE and SVI is of questionable benefit. These mpMRI reports may result in closer dissection of neurovascular bundles and subsequent positive surgical margins. Caution should be exercised when basing intraoperative decisions on mpMRI findings.

Sea spray aerosol as a unique source of ice nucleating particles.

Ice nucleating particles (INPs) are vital for ice initiation in, and precipitation from, mixed-phase clouds. A source of INPs from oceans within sea spray aerosol (SSA) emissions has been suggested in previous studies but remained unconfirmed. Here, we show that INPs are emitted using real wave breaking in a laboratory flume to produce SSA. The number concentrations of INPs from laboratory-generated SSA, when normalized to typical total aerosol number concentrations in the marine boundary layer, agree well with measurements from diverse regions over the oceans. Data in the present study are also in accord with previously published INP measurements made over remote ocean regions. INP number concentrations active within liquid water droplets increase exponentially in number with a decrease in temperature below 0 °C, averaging an order of magnitude increase per 5 °C interval. The plausibility of a strong increase in SSA INP emissions in association with phytoplankton blooms is also shown in laboratory simulations. Nevertheless, INP number concentrations, or active site densities approximated using "dry" geometric SSA surface areas, are a few orders of magnitude lower than corresponding concentrations or site densities in the surface boundary layer over continental regions. These findings have important implications for cloud radiative forcing and precipitation within low-level and midlevel marine clouds unaffected by continental INP sources, such as may occur over the Southern Ocean.