Soot Monitoring of Gasoline Particulate Filters Using a Radio-Frequency-Based Sensor.

Owing to increasingly stringent emission limits, particulate filters have become mandatory for gasoline-engine vehicles. Monitoring their soot loading is necessary for error-free operation. The state-of-the-art differential pressure sensors suffer from inaccuracies due to small amounts of stored soot combined with exhaust gas conditions that lead to partial regeneration. As an alternative approach, radio-frequency-based (RF) sensors can accurately measure the soot loading, even under these conditions, by detecting soot through its dielectric properties. However, they face a different challenge as their sensitivity may depend on the engine operation conditions during soot formation. In this article, this influence is evaluated in more detail. Various soot samples were generated on an engine test bench. Their dielectric properties were measured using the microwave cavity perturbation (MCP) method and compared with the corresponding sensitivity of the RF sensor determined on a lab test bench. Both showed similar behavior. The values for the soot samples themselves, however, differed significantly from each other. A way to correct for this cross-sensitivity was found in the influence of exhaust gas humidity on the RF sensor, which can be correlated with the engine load. By evaluating this influence during significant humidity changes, such as fuel cuts, it could be used to correct the influence of the engineon the RF sensor.

Mixing Rules for an Exact Determination of the Dielectric Properties of Engine Soot Using the Microwave Cavity Perturbation Method and Its Application in Gasoline Particulate Filters.

In recent years, particulate filters have become mandatory in almost all gasoline-powered vehicles to comply with emission standards regarding particulate number. In contrast to diesel applications, monitoring gasoline particulate filters (GPFs) by differential pressure sensors is challenging due to lower soot masses to be deposited in the GPFs. A different approach to determine the soot loading of GPFs is a radio frequency-based sensor (RF sensor). To facilitate sensor development, in previous work, a simulation model was created to determine the RF signal at arbitrary engine operating points. To ensure accuracy, the exact dielectric properties of the soot need to be known. This work has shown how small samples of soot-loaded filter are sufficient to determine the dielectric properties of soot itself using the microwave cavity perturbation method. For this purpose, mixing rules were determined through simulation and measurement, allowing the air and substrate fraction of the sample to be considered. Due to the different geometry of filter substrates compared to crushed soot samples, a different mixing rule had to be derived to calculate the effective filter properties required for the simulation model. The accuracy of the determined mixing rules and the underlying simulation model could be verified by comparative measurements on an engine test bench.

Quality of life in uncomplicated recurrent diverticulitis: surgical vs. conservative treatment.

Elective sigmoid colectomy for recurrent uncomplicated diverticulitis remains controversial and is decided on an individual basis. Eighty patients treated conservatively (44 patients) or by elective surgery (36 patients) for recurrent uncomplicated diverticulitis were contacted and assessed for quality of life. The mean difference in quality of life scores was greater after surgery (overall + 2.14%, laparoscopic resection +4.95%, p = 0.36 and p = 0.11, respectively) as compared to conservative management. Female patients undergoing laparoscopic resection had statistically significantly higher quality of life scores than women treated conservatively (+8.98%; p = 0.049). Twenty-eight of 29 responding patients stated that they were highly satisfied and would have the operation done again. Elective sigmoidectomy is a valid treatment option for recurrent uncomplicated diverticulitis in terms of quality of life. Quality of life improved most if surgery was performed laparoscopically, especially in women.

Modelling the Influence of Different Soot Types on the Radio-Frequency-Based Load Detection of Gasoline Particulate Filters.

Gasoline particulate filters (GPFs) are an appropriate means to meet today's emission standards. As for diesel applications, GPFs can be monitored via differential pressure sensors or using a radio-frequency approach (RF sensor). Due to largely differing soot properties and engine operating modes of gasoline compared to diesel engines (e.g., the possibility of incomplete regenerations), the behavior of both sensor systems must be investigated in detail. For this purpose, extensive measurements on engine test benches are usually required. To simplify the sensor development, a simulation model was developed using COMSOL Multiphysics® that not only allowed for calculating the loading and regeneration process of GPFs under different engine operating conditions but also determined the impact on both sensor systems. To simulate the regeneration behavior of gasoline soot accurately, an oxidation model was developed. To identify the influence of different engine operating points on the sensor behavior, various samples generated at an engine test bench were examined regarding their kinetic parameters using thermogravimetric analysis. Thus, this compared the accuracy of soot mass determination using the RF sensor with the differential pressure method. By simulating a typical driving condition with incomplete regenerations, the effects of the soot kinetics on sensor accuracy was demonstrated exemplarily. Thereby, the RF sensor showed an overall smaller mass determination error, as well as a lower dependence on the soot kinetics.

Neoadjuvant FOLFIRINOX in Patients With Borderline Resectable Pancreatic Cancer: A Systematic Review and Patient-Level Meta-Analysis.

BACKGROUND: FOLFIRINOX is a standard treatment for metastatic pancreatic cancer patients. The effectiveness of neoadjuvant FOLFIRINOX in patients with borderline resectable pancreatic cancer (BRPC) remains debated. METHODS: We performed a systematic review and patient-level meta-analysis on neoadjuvant FOLFIRINOX in patients with BRPC. Studies with BRPC patients who received FOLFIRINOX as first-line neoadjuvant treatment were included. The primary endpoint was overall survival (OS), and secondary endpoints were progression-free survival, resection rate, R0 resection rate, and grade III-IV adverse events. Patient-level survival outcomes were obtained from authors of the included studies and analyzed using the Kaplan-Meier method. RESULTS: We included 24 studies (8 prospective, 16 retrospective), comprising 313 (38.1%) BRPC patients treated with FOLFIRINOX. Most studies (n = 20) presented intention-to-treat results. The median number of administered neoadjuvant FOLFIRINOX cycles ranged from 4 to 9. The resection rate was 67.8% (95% confidence interval [CI] = 60.1% to 74.6%), and the R0-resection rate was 83.9% (95% CI = 76.8% to 89.1%). The median OS varied from 11.0 to 34.2 months across studies. Patient-level survival data were obtained for 20 studies representing 283 BRPC patients. The patient-level median OS was 22.2 months (95% CI = 18.8 to 25.6 months), and patient-level median progression-free survival was 18.0 months (95% CI = 14.5 to 21.5 months). Pooled event rates for grade III-IV adverse events were highest for neutropenia (17.5 per 100 patients, 95% CI = 10.3% to 28.3%), diarrhea (11.1 per 100 patients, 95% CI = 8.6 to 14.3), and fatigue (10.8 per 100 patients, 95% CI = 8.1 to 14.2). No deaths were attributed to FOLFIRINOX. CONCLUSIONS: This patient-level meta-analysis of BRPC patients treated with neoadjuvant FOLFIRINOX showed a favorable median OS, resection rate, and R0-resection rate. These results need to be assessed in a randomized trial.

Preoperative treatment with capecitabine, cetuximab and radiotherapy for primary locally advanced rectal cancer--a phase II clinical trial.

BACKGROUND/AIM: To investigate the feasibility and safety of preoperative capecitabine, cetuximab and radiation in patients with MRI-defined locally advanced rectal cancer (LARC, cT3/T4). PATIENTS AND METHODS: 31 patients with LARC were treated with cetuximab and capecitabine concomitantly with 45 Gy radiotherapy and resected by total mesorectal excision. Histopathological response and association with KRAS status was evaluated. RESULTS: R0-resection was possible in 27 of 31 (86%) patients. No complete pathological remission was observed. Radiochemotherapy with capecitabine and cetuximab was safe to administer and diarrhea was the main toxicity. KRAS-status did not correlate to down-staging or pathological response concerning T- or N-stage. CONCLUSION: Neoadjuvant therapy with capecitabine and cetuximab in combination with radiotherapy did not lead to complete pathological remission. Treatment tolerability was excellent and toxicity remained low. KRAS status did not influence treatment outcomes. Capecitabine in combination with radiotherapy remains a standard therapy for locally advanced rectal cancer.

Preoperative treatment with capecitabine, bevacizumab and radiotherapy for primary locally advanced rectal cancer--a two stage phase II clinical trial.

BACKGROUND AND PURPOSE: The aim of this single-arm multicenter phase II clinical trial was to assess the feasibility and tolerability of preoperative radiotherapy and simultaneous capecitabine and bevacizumab. Secondary endpoints were downstaging-rate and induction of complete pathological response. MATERIAL AND METHODS: Patients with cT3 rectal cancer were eligible. Capecitabine (825 mg/sqm twice daily on radiotherapy-days weeks 1-4) and bevacizumab (5 mg/kg on days 1, 15 and 29) were administered concurrently to pelvic radiotherapy (1.8 Gy daily up to 45 Gy in 5 weeks). Surgery followed 6-8 weeks later. A two-stage trial was designed with early termination at eight patients if more than three patients had experienced a common toxicity criteria ≥grade 3 according to the NCI CTC guidelines. RESULTS: In the first stage eight patients were enrolled. Median age was 70 years (range 55-76) and ECOG PS 0/1 (%) was 87.5/12.5. Major side effects were mostly intestinal bleeding (grade 3, 25%), diarrhea (grade 3, 25%), perianal and abdominal pain (grades 3 and 4, 25%) followed by anemia (grade 3, 12.5%). Tumor downstaging was observed in 37.5% of patients with complete pathological response in two patients (25%). CONCLUSIONS: After interim analysis of feasibility and tolerability, accrual was terminated according to protocol due to ≥grade 3 toxicities in 50% of patients. Complete pathological response was seen in 25% of patients but was accompanied by considerable toxicity. Further clinical trials are needed to clarify the role of bevacizumab in this setting.

Preoperative oxaliplatin, capecitabine, and external beam radiotherapy in patients with newly diagnosed, primary operable, cT3NxM0, low rectal cancer: a phase II study.

PURPOSE: In patients with locally advanced rectal cancer (LARC), preoperative chemoradiation is known to improve local control, and down-staging of the tumor serves as a surrogate for survival. Intensification of the systemic therapy may lead to higher downstaging rates and, thus, enhance survival. This phase II study investigated the efficacy and safety of preoperative capecitabine and oxaliplatin in combination with radiotherapy. PATIENTS AND METHODS: Patients with LARC of the mid and lower rectum, T3NxM0 staged by MRI received radiotherapy (total dose 45 Gy) in combination with oral capecitabine (825 mg/m² twice a day on radiotherapy days; weeks 1-4) and oxaliplatin 50 mg/m² intravenously (days 1, 8, 15, and 22). Efficacy was evaluated as rate of tumor down-categorization at the T level. RESULTS: A total of 59 patients were enrolled (19 women, 40 men; median age of 61 years) and all were evaluable for efficacy and toxicity. Down-categorization at the T level was observed in 53% with pathological complete response in 6 patients (10%). Actual total radiotherapy, oxaliplatin and capecitabine doses received were 97%, 90%, and 93% of the protocol-specified preplanned doses, respectively. Grade 3/4 toxicity was observed in 15 patients (25%). The most frequent was diarrhea (12%). CONCLUSIONS: Preoperative chemoradiation with capecitabine and oxaliplatin is feasible in patients with MRI-proven cT3 LARC. The only clinically relevant toxicity was diarrhea. Overall, efficacy of the multimodality treatment was good, but not markedly exceeding that of 5-FU- or capecitabine-based chemoradiation approaches.