A direct method to quantify methanol-soluble organic carbon for brown carbon absorption studies

The current research provides a newly developed method to quantify methanol-soluble organic carbon (MeS_OC) in aerosol samples. This analytical procedure allows an accurate separation of MeS-OC component, which is critical for the calculation of mass absorption efficiency (MAE) of ambient Brown Carbon (BrC) and consequently its climate relevant potential. The method includes extraction, filtering and condensation stages, leading to the preparation of a highly concentrated product in which MeS-OC can be precisely quantified by a Sunset Carbon Analyzer in a single analysis step. This method can be applied on aerosol collected using either high or low volume samplers, since a relatively small filter area is required for the determination. Furthermore, it eliminates any misestimation of the MeS-OC mass that may appear in other reported techniques that don't seem to include the precise separation of methanol-soluble fraction in their quantification process.•The mass quantification of methanol-soluble organic carbon is essential, contributing up to 50% to the absorptivity of organic aerosol (BrC) at shorter wavelengths.•The method provides a direct measurement of methanol-soluble aerosol components, resolving any potential uncertainties of previously applied methods.•The adoption of this direct quantification approach leads to a rationalization of past MAE estimates for BrC with implications for radiative transfer models.

Brown carbon absorption and radiative effects under intense residential wood burning conditions in Southeastern Europe: New insights into the abundance and absorptivity of methanol-soluble organic aerosols

Biomass burning is a major source of Brown Carbon (BrC), strongly contributing to radiative forcing. In urban areas of the climate-sensitive Southeastern European region, where strong emissions from residential wood burning (RWB) are reported, radiative impacts of carbonaceous aerosols remain largely unknown. This study examines the absorption properties of water- and methanol-soluble organic carbon (WSOC, MeS_OC) in a city (Ioannina, Greece) heavily impacted by RWB. Measurements were performed during winter (December 2019 - February 2020) and summer (July - August 2019) periods, characterized by RWB and photochemical processing of organic aerosol (OA), respectively. PM_2.5 filter extracts were analyzed spectrophotometrically for water- and methanol-soluble BrC (WS_BrC, MeS_BrC) absorption. WSOC concentrations were quantified using TOC analysis, while those of MeS_OC were determined using a newly developed direct quantification protocol, applied for the first time to an extended series of ambient samples. The direct method led to a mean MeS_OC/OC of 0.68 and a more accurate subsequent estimation of absorption efficiencies. The mean winter WS_BrC and MeS_BrC absorptions at 365 nm were 13.9 Mm^-1 and 21.9 Mm^-1, respectively, suggesting an important fraction of water-insoluble OA. Mean winter WS_BrC and MeS_BrC absorptions were over 10 times those observed in summer. MeS_OC was more absorptive than WSOC in winter (mean mass absorption efficiencies - MAE₃₆₅: 1.81 vs 1.15 m² gC^-1) and especially in summer (MAE: 1.12 vs 0.27 m² gC^-1) due to photo-dissociation and volatilization of BrC chromophores. The winter radiative forcing (RF) of WS_BrC and MeS_BrC relative to elemental carbon (EC) was estimated at 8.7 % and 16.7 %, respectively, in the 300-2500 nm band. However, those values increased to 48.5 % and 60.2 % at 300-400 nm, indicating that, under intense RWB, BrC forcing becomes comparable to that of soot. The results highlight the consideration of urban BrC emissions in radiative transfer models, as a considerable climate forcing factor.

Ablation techniques in non-small cell lung cancer patients: experience of a single center

BACKGROUND

Percutaneous radiofrequency ablation (RFA) and microwave ablation (MWA) are well-established treatments for patients with non-small cell lung cancer (NSCLC). This study assessed the efficacy and safety of RFA and MWA performed on NSCLC patients.

MATERIAL AND METHODS

This retrospective study included one hundred twenty-four patients with NSCLC who underwent percutaneous ablation from November 2014 to November 2020 in the Department of Medical Imaging and Interventional Radiology of Sotiria General Hospital for Chest Diseases in Athens, Greece. Forty (stage IA) were treated with RFA, while 84 were treated with MWA (stages IA, IB, and IIA). All procedures were performed using the AMICA GEN radiofrequency and microwave generator. As a follow-up method, computed tomography was performed immediately after the procedure to evaluate the lesion's response and complications and one, three, six, and twelve months after the ablation.

RESULTS

All ablations were technically successful. The first-month follow-up revealed stage IIA residual tumors in eight patients. Local recurrence was detected one year after RFA in two of the 40 patients and thirteen of the 84 patients after MWA. Overall survival (OS) rates at one, two, and three years for stage IA NSCLC patients treated with ablation were 94 %, 73 %, 57 % for RFA, and 96 %, 75 %, and 62 % for MWA, respectively. In contrast, the OS for stages IB and IIA patients treated with MWA was 90 %, 66 %, and 51 % for the IB stage and 82 %, 62 %, and 48 % for the IIA stage, respectively. Fifteen percent of patients after RFA and 9.5 % after MWA experienced minor complications. Pneumothorax was documented in three patients after RFA and four after MWA. Post-ablation syndrome occurred in 15 % of RFA patients and 8.3 % of MWA patients. There were no major complications.

CONCLUSION

RFA and MWA have comparable efficacy and safety for patients in stage IA. MWA is an effective alternative treatment option for non-resectable IB or IIA stages NSCLC patients. HIPPOKRATIA 2022, 26 (3):105-109.

Contrast-enhanced ultrasound for imaging blunt abdominal trauma - indications, description of the technique and imaging review

Patients with blunt abdominal trauma are initially imaged with ultrasound (US) for the evaluation of free abdominal fluid. However, lacerations of solid organs can be overlooked. Although computed tomography (CT) is the gold standard technique for abdominal trauma imaging, overutilization, ionizing radiation, need to transport the patient and potential artifacts are well known disadvantages. Contrast-enhanced US (CEUS) can be used as an imaging tool between the two methods. It can easily and reliably reveal solid abdominal organ injuries in patients with low-energy localized trauma and decrease the number of CT scans performed. It can be rapidly performed at the patient's bedside with no need for transportation. There are only very few contraindications and anaphylactoid reactions are extremely rare. Altogether, CEUS has proved to be very helpful for the initial imaging of traumatic lesions of the liver, kidney and spleen, as well as for patient follow-up.

Hydatid hepatic cysts rupture into the biliary tract, the peritoneal cavity, the thoracic cavity and the hepatic subcapsular space: specific computed tomography findings

BACKGROUND

This study attempts to demonstrate the role of computed tomography in the diagnosis of hepatic hydatid cyst rupture based on specific imaging findings and to propose combinations of the imaging findings diagnostic for specific types of rupture.

METHODS

Eleven patients were studied with computed tomography of the abdomen, with 4-8 mm slice thickness, after the oral administration of contrast material and intravenous contrast material in 6 cases.

RESULTS

Based on a combination of imaging findings the types of hepatic hydatid cyst rupture were: intrabiliary rupture in 7 patients, intraperitoneal rupture in 1 patient, intrathoracic rupture in 1 patient, hepatic subcapsular rupture in 2 patients. Structural deformity of the cyst was present in all cases, combined with: dilatation of the intrahepatic bile ducts (intrabiliary rupture); intraperitoneal fluid collections with diffuse haziness and stranding of the mesenteric fat (intraperitoneal rupture); an inhomogeneous lesion in the thorax with ipsilateral pleural effusion (intrathoracic rupture); a hydatid cyst located peripherally, with discontinuity of its adjacent to the hepatic capsule wall and subcapsular fluid collection (subcapsular rupture). The imaging findings were surgically and pathologically confirmed.

CONCLUSIONS

Using combinations of specific imaging findings we correctly diagnosed the type of hepatic hydatid cyst rupture in all cases.