Experimental study of foam propagation and stability in highly permeable porous media under lateral water flow: Diverting groundwater for application to soil remediation.

Foam propagation and stability in highly permeable porous media, encountered in soil pollution applications, are still challenging. Here, we investigated the application of foam for blocking the aquifer to divert the flow from a contaminated zone and, therefore, ease the remediation treatments. The main aim was to better understand the critical parameters when the foam is injected into a highly permeable aquifer with high groundwater flow velocity (up to 10 m/day). A decimetric-scale 2D tank experimental setup filled with 1 mm glass beads was used. The front part of the 2D tank was made of transparent glass to photograph the foam flow using the light-reflected method. The water flow was generated horizontally through injection and pumping points on the sides of the tank. The pre-generated foam was injected at the bottom center of the tank. Water streamlines (using dye tracing) and water saturation were investigated using image interpretation. Results show that 100% of the water flow was diverted during the injection of the foam. Foam stability in porous media depends significantly on the horizontal water flow rate. Recirculating water containing the surfactant increases foam stability. The main mechanism of destruction was identified as the dilution of the surfactant in water. However, the head-loss measurements showed that despite foam destruction, the relative permeability of the water phase in the media remained quite low. Injection of foam increases the radius of gas propagation, thanks to foam's high viscosity, compared to a pure gas injection case. These results are new highlights on the efficiency of foam as a blocking agent, showing that it can also serve as a means for gas transport more efficiently in porous media, especially for soil remediation applications.

Controlled treatment of a high velocity anisotropic aquifer model contaminated by hexachlorocyclohexanes.

Xanthan gels were assessed to control the reductive dechlorination of hexachlorocyclohexanes (HCHs) and trichlorobenzenes (TCBs) in a strong permeability contrast and high velocity sedimentary aquifer. An alkaline degradation was selected because of the low cost of NaOH and Ca(OH)2. The rheology of alkaline xanthan gels and their ability to deliver alkalinity homogeneously, while maintaining the latter, were studied. Whereas the xanthan gels behaved like non-Newtonian shear-thinning fluids, alkalinity and Ca(OH)2 microparticles had detrimental effects, yet, the latter decreased with the shear-rate. Breakthrough curves for the NaOH and Ca(OH)2 in xanthan solutions, carried out in the lowest permeability soil (9.9 µm2), demonstrated the excellent transmission of alkalinity, while moderate pressure gradients were applied. Injection velocities ranging from 1.8 to 3.8 m h-1 are anticipated in the field, given the permeability range from 9.9 to 848.7 µm2. Despite a permeability contrast of 8.7 in an anisotropic aquifer model, the NaOH and the Ca(OH)2 both in xanthan gels spread only 5- and 7-times faster in the higher permeability zone, demonstrating that the delivery was enhanced. Moreover, the alkaline gels which were injected into a high permeability layer under lateral water flow, showed a persistent blocking effect and longevity (timescale of weeks), in contrast to the alkaline solution in absence of xanthan. Kinetics of alkaline dechlorination carried out on the historically contaminated soil, using the Ca(OH)2 suspension in xanthan solution, showed that HCHs were converted in TCBs by dehydrodechlorination, whereas the latter were then degraded by reductive hydrogenolysis. Degradation kinetics were achieved within 30 h for the major and most reactive fraction of HCHs.

Adenoma detection with blue-water infusion colonoscopy: a randomized trial.

Background and aims Colonoscopy is currently the reference method to detect colorectal neoplasia, yet some adenomas remain undetected. The water infusion technique and dying with indigo carmine has shown interesting results for reducing this miss rate. The aim of this study was to compare the adenoma detection rate (adenoma and adenocarcinoma; ADR) and the mean number of adenomas per patient (MAP) for blue-water infusion colonoscopy (BWIC) versus standard colonoscopy. Methods We performed a multicenter, randomized controlled trial in eight units, including patients with a validated indication for colonoscopy (symptoms, familial or personal history, fecal occult blood test positive). Consenting patients were randomized 1:1 to BWIC or standard colonoscopy. All colonoscopies were performed by experienced colonoscopists. All colonoscopy quality indicators were prospectively recorded. Results Among the 1065 patients included, colonoscopies were performed completely for 983 patients (514 men; mean age 59.1). The ADR was not significantly different between the groups; 40.4 % in the BWIC group versus 37.5 % in the standard colonoscopy group (odds ratio [OR] 1.13; 95 % confidence interval [CI] 0.87 - 1.48; P = 0.35). MAP was significantly greater in the BWIC group (0.79) than in the standard colonoscopy group (0.64; P = 0.005). For advanced adenomas, the results were 50 (10.2 %) and 36 (7.3 %), respectively (P = 0.10). The cecal intubation rate was not different but the time to cecal intubation was significantly longer in BWIC group (9.9 versus 6.2 minutes; P < 0.001). Conclusion Despite the higher MAP with BWIC, the routine use of BWIC does not translate to a higher ADR. Whether increased detection ultimately results in a lower rate of interval carcinoma is not yet known. CLINICAL TRIALS REGISTRATION: EudraCT 2012-A00548 - 35; NCT01937429.

PAH oxidation in aged and spiked soils investigated by column experiments.

Soils of former steel-making or coking plants have been contaminated for decades by PAHs. These soils could be cleaned up by In situ chemical oxidation (ISCO) but the low PAH availability may be a drawback. The objective of the present contribution was to study the efficiency of PAH oxidation in two aged soils compared to a spiked soil in dynamic conditions. Column experiments were performed with two oxidants: hydrogen peroxide used in modified Fenton's reaction and activated persulfate. The oxidant doses were moderate to ensure the feasibility of process upscaling. Besides, the availability of PAHs in these soils was measured by extraction with a cyclodextrin. Our results showed that oxidation was limited: the higher PAH degradation rate was 30% with the aged soils and 55% with the spiked one. PAH availability was a parameter explaining these results but no direct correlation was found between PAH extractability by the cyclodextrin and oxidation efficiency. Other parameters were also involved, such as the organic carbon content, the calcite content and the pH. This study was a first achievement before studying the influence of a number of parameters on the efficiency of PAH oxidation in aged soils.

Persistence of Bacillus thuringiensis israelensis (Bti) in the environment induces resistance to multiple Bti toxins in mosquitoes.

BACKGROUND: The simultaneous production of six different toxins by Bacillus thuringiensis israelensis (Bti) is thought to delay the evolution of resistance in treated mosquito populations. Recent studies have shown that Bti can persist and proliferate in the environment, thereby imposing continuous selective pressure on mosquito populations, raising concerns about the long-term effectiveness of this bioinsecticide. In order to evaluate the effect of Bti persistence on the evolution of resistance, the authors selected a laboratory Aedes aegypti L. strain with field-collected leaf litter containing Bti toxins. RESULTS: It is shown that resistance to each individual Bti toxin (up to 30-fold) can be obtained after only a few generations of selection. However, the resistance to commercial Bti and to environmental Bti remains low (twofold and 3.4-fold respectively) in the selected strain. Furthermore, some selected individuals exhibited resistance to Cry4B but not to Cry4A, suggesting that two distinct resistance mechanisms are involved in the resistance to these two toxins. CONCLUSION: Considering that resistance to Cry toxins might act as a first step to resistance to a complete Bti toxin mixture, the present results highlight the importance of testing each toxin individually in order accurately to monitor Bti toxin resistance evolution in field populations.

Phase I study of daily irinotecan as a radiation sensitizer for locally advanced pancreatic cancer.

PURPOSE: The study aimed to determine the maximum tolerated dose of daily irinotecan given with concomitant radiotherapy in patients with locally advanced adenocarcinoma of the pancreas. METHODS AND MATERIALS: Between September 2000 and March 2008, 36 patients with histologically proven unresectable pancreas adenocarcinoma were studied prospectively. Irinotecan was administered daily, 1 to 2 h before irradiation. Doses were started at 6 mg/m(2) per day and then escalated by increments of 2 mg/m(2) every 3 patients. Radiotherapy was administered in 2-Gy fractions, 5 fractions per week, up to a total dose of 50 Gy to the tumor volume. Inoperability was confirmed by a surgeon involved in a multidisciplinary team. All images and responses were centrally reviewed by radiologists. RESULTS: Thirty-six patients were enrolled over a period of 8 years through eight dose levels (6 mg/m(2) to 20 mg/m(2) per day). The maximum tolerated dose was determined to be 18 mg/m(2) per day. The dose-limiting toxicities were nausea/vomiting, diarrhea, anorexia, dehydration, and hypokalemia. The median survival time was 12.6 months with a median follow-up of 53.8 months. The median progression-free survival time was 6.5 months, and 4 patients (11.4%) with very good responses could undergo surgery. CONCLUSIONS: The maximum tolerated dose of irinotecan is 18 mg/m(2) per day for 5 weeks. Dose-limiting toxicities are mainly gastrointestinal. Even though efficacy was not the aim of this study, the results are very promising, with a median survival time of 12.6 months.

[Subcapsular hepatic hematoma after endoscopic retrograde cholangiopancreatography: case report and literature review]. / Hématome sous-capsulaire hépatique après cholangiopancréatographie rétrograde endoscopique: description d'un cas clinique et revue de littérature.

Subcapsular hepatic hematoma is a rare complication of endoscopic retrograde cholangiopancreatography. The mechanism of this lesion has not been clearly established. The following observation clarifies the physiopathology, as well as providing a review of the various cases described in the literature.

Prospective evaluation of a new ultrathin one-plane bending videoendoscope for transnasal EGD: a comparative study on performance and tolerance.

BACKGROUND: EGD, with small-diameter endoscopes, is routinely performed via a nasal route in adults. OBJECTIVE: To evaluate a new ultrathin one-plane bending videoendoscope for transnasal EGD. DESIGN: Single center, prospective, randomized study. SETTING: Edouard Herriot University Hospital. PATIENTS: A total of 122 outpatients (median age, 49 years [18-81 years], 62 men and 60 women) were randomized into 2 groups (on a 2:1 basis) according to the endoscope used: (1) a standard 5.9-mm-diameter videoendoscope (80 patients) or (2) a one-plane bending high resolution 4.9-mm-diameter videoendoscope (42 patients). MAIN OUTCOME MEASUREMENTS: The operator assessed the quality of examination by using standard scores or a 100-mm visual scale. Patients quantified tolerance by using a 100-mm visual scale. RESULTS: The duration of the procedure was the same in each group. The feasibility of transnasal insertion was significantly higher when using the 4.9-mm-diameter endoscope (97.61% [41/42 patients] vs 88.75% [71/80 patients], P<.05). The tolerance of EGD was significantly better in the group with the small videoendoscope, for global discomfort, pain, belching, and bloating. Similarly, acceptation of a new EGD in similar conditions was higher in group 2 (92.9% vs 80%, P<.05). The quality of examination (global, lavage, inflation, suction) was not different between the 2 groups. LIMITATIONS: Evaluation of patient tolerance and quality of examination was based on subjective features. CONCLUSIONS: Availability of a new ultrathin one-plane bending videoendoscope represents a major technical improvement for transnasal EGD, which significantly improves both feasibility and patient tolerance, without affecting the quality of the examination.