Channeling is a distinct class of dissolution in complex porous media.

The traditional model of solid dissolution in porous media consists of three dissolution regimes (uniform, compact, wormhole)-or patterns-that are established depending on the relative dominance of reaction rate, flow, and diffusion. In this work, we investigate the evolution of pore structure using numerical simulations during acid injection on two models of increasing complexity. We investigate the boundaries between dissolution regimes and characterize the existence of a fourth dissolution regime called channeling, where initially fast flow pathways are preferentially widened by dissolution. Channeling occurs in cases where the distribution in pore throat size results in orders of magnitude differences in flow rate for different flow pathways. This focusing of dissolution along only dominant flow paths induces an immediate, large change in permeability with a comparatively small change in porosity, resulting in a porosity-permeability relationship unlike any that has been previously seen. This work suggests that the traditional conceptual model of dissolution regimes must be updated to incorporate the channeling regime for reliable forecasting of dissolution in applications like geothermal energy production and geologic carbon storage.

Results of endoscopic biliary drainage in patients with malignant hilar stricture.

In Malignant Hilar Biliary Stricture (MHBS) palliative biliary drainage is a frequent strategy, improving the quality of life, reducing pruritus, loss of appetite and relieving cholangitis. The endoscopic approach is an effective, although challenging procedure. This study aimed to evaluate technical and clinical success rates of biliary drainage by ERCP. This is a retrospective study including all patients with MHBS referred to Instituto do Cancer do Hospital de São Paulo (ICESP) submitted to biliary drainage by ERCP, between January 2010 and December 2017. Multivariable logistic regression was performed to evaluate predictors of clinical failure, as total bilirubin levels, Bismuth classification, number of hepatic sectors drained and presence of cholangitis. In total, 82 patients presenting unresectable MHBS were included in this study. 58.5% female and 41.5% male, with a mean age of 60±13 years. Bismuth classification grades II, IIIA, IIIB and IV were noted in 23.2%, 15.9%, 14.6% and 46.3%, respectively. Technical and clinical success was achieved in 92.7% and 53.7% respectively. At multivariable logistic-regression analyses, Bismuth IV strictures were related to higher clinical failure rates when compared to other strictures levels, with an Odds Ratio of 5.8 (95% CI 1.28‒20.88). In conclusion, endoscopic biliary drainage for malignant hilar biliary stricture had a high technical success but suboptimal clinical success rate. Proximal strictures (Bismuth IV) were associated with poor drainage outcomes.

Underwater versus conventional EMR for nonpedunculated colorectal lesions: a randomized clinical trial.

BACKGROUND AND AIMS: Conventional endoscopic mucosal resection (CEMR) is the standard modality for removing nonpedunculated colorectal lesions. Underwater endoscopic mucosal resection (UEMR) has emerged as an alternative method. There are few comparative studies between these techniques, especially evaluating recurrence. Therefore, the purpose of this trial was to compare CEMR and UEMR for the resection of colorectal lesions with respect to efficacy, safety, and recurrence rate. METHODS: This was a randomized controlled trial of UEMR versus CEMR for naïve and nonpedunculated lesions measuring between 10 and 40 mm. The primary outcome was adenoma recurrence at 6 months after the resection. Secondary outcomes were rates of technical success, en bloc resection, and adverse events. Block randomization was used to assign patients. Tattooing was performed to facilitate localization of the scars and eventual recurrences. Endoscopic follow-up was scheduled at 6 months after the procedure. The sites of resections were examined with white-light imaging, narrow-band imaging (NBI), and conventional chromoscopy with indigo carmine followed by biopsies. RESULTS: One hundred five patients with 120 lesions were included, with a mean size of 17.5 ± 7.1 (SD) mm. Sixty-one lesions were resected by UEMR and 59 by CEMR. The groups were similar at baseline regarding age, sex, average size, and histologic type. Lesions in the proximal colon in the CEMR group corresponded to 83% and in the UEMR group to 67.8% (P = .073). There was no difference between groups regarding success rate (1 failure in each group) and en bloc resection rate (60.6% UEMR vs 54.2% CEMR, P = .48). Intraprocedural bleeding was observed in 5 CEMRs (8.5%) and 2 UEMRs (3.3%) (P = .27). There was no perforation or delayed hemorrhage in either groups. Recurrence rate was higher in the CEMR arm (15%) than in the UEMR arm (2%) (P = .031). Therefore, the relative risk of 6-month recurrence rate in the CEMR group was 7.5-fold higher (95% CI, 0.98-58.20), with a number needed to treat of 7.7 (95% CI, 40.33-4.22). The higher recurrence rate in the CEMR group persisted only for lesions measuring 21 to 40 mm (35.7% vs 0%; P = .04). CONCLUSION: This study demonstrated that UEMR was associated with a lower adenoma recurrence rate than was CEMR. Both endoscopic techniques were effective and had similar rates of adverse events for the treatment of nonpedunculated colorectal lesions.

Pore-scale visualization of hydrogen storage in a sandstone at subsurface pressure and temperature conditions: Trapping, dissolution and wettability.

HYPOTHESIS: Underground hydrogen (H2) storage is a potentially viable solution for large-scale cyclic H2 storage; however, the behavior of H2 at subsurface pressure and temperature conditions is poorly known. This work investigates if the pore-scale displacement processes in H2-brine systems in a porous sandstone can be sufficiently well defined to enable effective and economic storage operations. In particular, this study investigates trapping, dissolution, and wettability of H2-brine systems at the pore-scale, at conditions that are realistic for subsurface H2 storage. EXPERIMENTS: We have performed in situ X-ray imaging during a flow experiment to investigate pore-scale processes during H2 injection and displacement in a brine saturated Bentheimer sandstone sample at temperature and pressure conditions representative of underground reservoirs. Two injection schemes were followed for imbibition: displacement of H2 with H2-equilibrated brine and with non-H2-equilibrated brine. The results from the two cycles were compared with each other. FINDINGS: The sandstone was found to be wetting to the brine and non-wetting to H2 after both displacement cycles, with average contact angles of 54° and 53° for H2-equilibrated and non-H2-equilibrated brine respectively. We also found a higher recovery of H2 (43.1%) when displaced with non-H2-equilibrated brine compared to that of H2-equilibrated brine (31.6%), indicating potential dissolution of H2 in the unequilibrated imbibing brine at reservoir conditions. Our results suggest that underground H2 storage may indeed be a suitable strategy for energy storage, but considerable further research is needed to fully comprehend the pore-scale interactions at reservoir conditions.

Results of endoscopic biliary drainage in patients with malignant hilar stricture

Abstract In Malignant Hilar Biliary Stricture (MHBS) palliative biliary drainage is a frequent strategy, improving the quality of life, reducing pruritus, loss of appetite and relieving cholangitis. The endoscopic approach is an effective, although challenging procedure. This study aimed to evaluate technical and clinical success rates of biliary drainage by ERCP. This is a retrospective study including all patients with MHBS referred to Instituto do Cancer do Hospital de São Paulo (ICESP) submitted to biliary drainage by ERCP, between January 2010 and December 2017. Multivariable logistic regression was performed to evaluate predictors of clinical failure, as total bilirubin levels, Bismuth classification, number of hepatic sectors drained and presence of cholangitis. In total, 82 patients presenting unresectable MHBS were included in this study. 58.5% female and 41.5% male, with a mean age of 60±13 years. Bismuth classification grades II, IIIA, IIIB and IV were noted in 23.2%, 15.9%, 14.6% and 46.3%, respectively. Technical and clinical success was achieved in 92.7% and 53.7% respectively. At multivariable logistic-regression analyses, Bismuth IV strictures were related to higher clinical failure rates when compared to other strictures levels, with an Odds Ratio of 5.8 (95% CI 1.28‒20.88). In conclusion, endoscopic biliary drainage for malignant hilar biliary stricture had a high technical success but suboptimal clinical success rate. Proximal strictures (Bismuth IV) were associated with poor drainage outcomes.

TC-325 hemostatic powder in the management of upper gastrointestinal malignant bleeding: a randomized controlled trial.

Background and study aims Upper gastrointestinal bleeding (UGIB) from malignancy is associated with high rebleeding and mortality rates. Recently, TC-325 powder has shown promising results in the treatment of UGIB, including malignant bleeding. The aim of this study was to compare the efficacy of TC-325 versus best clinical management. Patients and methods From August 2016 to February 2020, all patients with evidence of UGIB from malignancy were randomized to receive TC-325 therapy or control group, in which endoscopic treatment was not mandatory. Exclusion criteria were hemoglobin drop without overt bleeding and UGIB from non-tumor origin. The primary outcome was 30-day mortality. Secondary outcomes were 30-day rebleeding, blood transfusion and length of hospital stay. Results Sixty-two patients were randomized, three were excluded and 59 were included in the final analysis (TC-325 group = 28; control = 31). Groups were similar at baseline. Active bleeding was observed in 22 patients in the TC-325 group and 19 in the control group ( P  = 0.15). Successful initial hemostasis with TC-325 was achieved in all cases. Additional therapy (radiotherapy, surgery or arterial embolization) was equally performed in both groups (42.9 % vs 58.1 %; P  = 0.243). There were no differences in 30-day mortality (28.6 % vs. 19.4 %, P  = 0.406) or 30-day rebleeding rates (32.1 % vs. 19.4 %, P  = 0.26). Logistic regression identified no significant predictors of rebleeding. Age, Eastern Cooperative Oncology Group (ECOG) score 3 to 4 and AIMS65 score > 1 predicted greater mortality. Conclusions TC-325 was effective in achieving immediate hemostasis in malignant gastrointestinal bleeding but did not reduce 30-day mortality, 30-day rebleeding, blood transfusion or length of hospital stay. Age, ECOG 3-4, and AIMS65 > 1 were predictive factors of mortality.

Endoscopy infection control strategy during the COVID-19 pandemic: experience from a tertiary cancer center in Brazil.

OBJECTIVES: Strategic planning for coronavirus disease (COVID-19) care has dominated the agenda of medical services, which have been further restricted by the need for minimizing viral transmission. Risk is particularly relevant in relation to endoscopy procedures. This study aimed to describe a contingency plan for a tertiary academic cancer center, define a strategy to prioritize and postpone examinations, and evaluate the infection rate among healthcare workers (HCWs) in the endoscopy unit of the Cancer Institute of the State of São Paulo (ICESP). METHODS: We created a strategy to balance the risk of acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and to mitigate the effects of postponing endoscopic procedures in oncological patients. A retrospective analysis of prospectively collected data on all endoscopies between March and June 2020 compared with those during the same period in 2019 was carried out. All HCWs were interviewed to obtain clinical data and SARS-CoV-2 test results. RESULTS: During the COVID-19 outbreak, there was a reduction of 55% in endoscopy cases in total. Colonoscopy was the most affected modality. The total infection rate among all HCWs was 38%. None of the senior digestive endoscopists had COVID-19. However, all bronchoscopists had been infected. One of three fellows had a serological diagnosis of COVID-19. Two-thirds of all nurses were infected, whereas half of all technicians were infected. CONCLUSIONS: In this pandemic scenario, all endoscopy services must prioritize the procedures that will be performed. It was possible to maintain some endoscopic procedures, including those meant to provide nutritional access, tissue diagnosis, and endoscopic resection. Personal protective equipment (PPE) seems effective in preventing transmission of COVID-19 from patients to digestive endoscopists. These measures can be useful in planning, even for pandemics in the future.

Poromechanical controls on spontaneous imbibition in earth materials.

Over the last century, the state of stress in the earth's upper crust has undergone rapid changes because of human activities associated with fluid withdrawal and injection in subsurface formations. The stress dependency of multiphase flow mechanisms in earth materials is a substantial challenge to understand, quantify, and model for many applications in groundwater hydrology, applied geophysics, CO2 subsurface storage, and the wider geoenergy field (e.g., geothermal energy, hydrogen storage, hydrocarbon recovery). Here, we conduct core-scale experiments using N2/water phases to study primary drainage followed by spontaneous imbibition in a carbonate specimen under increasing isotropic effective stress and isothermal conditions. Using X-ray computed micro-tomography images of the unconfined specimen, we introduce a novel coupling approach to reconstruct pore-deformation and simulate multiphase flow inside the deformed pore-space followed by a semi-analytical calculation of spontaneous imbibition. We show that the irreducible water saturation increases while the normalized volume of spontaneously imbibed water into the specimen decreases (46-25%) in response to an increase in effective stress (0-30 MPa), leading to higher residual gas saturations. Furthermore, the imbibition rate decreases with effective stress, which is also predicted by a numerical model, due to a decrease in water relative permeability as the pore-space becomes more confined and tortuous. This fundamental study provides new insights into the physics of multiphase fluid transport, CO2 storage capacity, and recovery of subsurface resources incorporating the impact of poromechanics.

Endoscopy infection control strategy during the COVID-19 pandemic: experience from a tertiary cancer center in Brazil

OBJECTIVES: Strategic planning for coronavirus disease (COVID-19) care has dominated the agenda of medical services, which have been further restricted by the need for minimizing viral transmission. Risk is particularly relevant in relation to endoscopy procedures. This study aimed to describe a contingency plan for a tertiary academic cancer center, define a strategy to prioritize and postpone examinations, and evaluate the infection rate among healthcare workers (HCWs) in the endoscopy unit of the Cancer Institute of the State of São Paulo (ICESP). METHODS: We created a strategy to balance the risk of acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and to mitigate the effects of postponing endoscopic procedures in oncological patients. A retrospective analysis of prospectively collected data on all endoscopies between March and June 2020 compared with those during the same period in 2019 was carried out. All HCWs were interviewed to obtain clinical data and SARS-CoV-2 test results. RESULTS: During the COVID-19 outbreak, there was a reduction of 55% in endoscopy cases in total. Colonoscopy was the most affected modality. The total infection rate among all HCWs was 38%. None of the senior digestive endoscopists had COVID-19. However, all bronchoscopists had been infected. One of three fellows had a serological diagnosis of COVID-19. Two-thirds of all nurses were infected, whereas half of all technicians were infected. CONCLUSIONS: In this pandemic scenario, all endoscopy services must prioritize the procedures that will be performed. It was possible to maintain some endoscopic procedures, including those meant to provide nutritional access, tissue diagnosis, and endoscopic resection. Personal protective equipment (PPE) seems effective in preventing transmission of COVID-19 from patients to digestive endoscopists. These measures can be useful in planning, even for pandemics in the future.

UNDERWATER ENDOSCOPIC MUCOSAL RESECTION FOR NON-PEDUNCULATED COLORECTAL LESIONS. A PROSPECTIVE SINGLE-ARM STUDY.

BACKGROUND: Underwater endoscopic mucosal resection (UEMR) has emerged as a revolutionary method allowing resection of colorectal lesions without submucosal injection. Brazilian literature about this technique is sparse. OBJECTIVE: The aim of this study was evaluate the efficacy and safety of UEMR technique for removing non-pedunculated colorectal lesions in two Brazilian tertiary centers. METHODS: This prospective study was conducted between June 2016 and May 2017. Naïve and non-pedunculated lesions without signs of submucosal invasion were resected using UEMR technique. RESULTS: A total of 55 patients with 65 lesions were included. All lesions, except one, were successfully and completely removed by UEMR (success rate 98.5%). During UEMR, two cases of bleeding were observed (3.0%). One patient had abdominal pain on the day after resection without pneumoperitoneum. There was no perforation or delayed bleeding. CONCLUSION: This study supports the existing data indicating acceptable rates of technical success, and low incidence of adverse events with UEMR. The results of this Brazilian study were consistent with previous abroad studies.

Ressecção da mucosa endoscópica sob imersão dágua para lesões colorretais não pediculadas. Um estudo prospectivo de braço único / Underwater endoscopic mucosal resection for non-pedunculated colorectal lesions. a prospective single-arm study

ABSTRACT BACKGROUND: Underwater endoscopic mucosal resection (UEMR) has emerged as a revolutionary method allowing resection of colorectal lesions without submucosal injection. Brazilian literature about this technique is sparse. OBJECTIVE: The aim of this study was evaluate the efficacy and safety of UEMR technique for removing non-pedunculated colorectal lesions in two Brazilian tertiary centers. METHODS: This prospective study was conducted between June 2016 and May 2017. Naïve and non-pedunculated lesions without signs of submucosal invasion were resected using UEMR technique. RESULTS: A total of 55 patients with 65 lesions were included. All lesions, except one, were successfully and completely removed by UEMR (success rate 98.5%). During UEMR, two cases of bleeding were observed (3.0%). One patient had abdominal pain on the day after resection without pneumoperitoneum. There was no perforation or delayed bleeding. CONCLUSION: This study supports the existing data indicating acceptable rates of technical success, and low incidence of adverse events with UEMR. The results of this Brazilian study were consistent with previous abroad studies.

RESUMO CONTEXTO: A ressecção endoscópica da mucosa sob imersão d'água (REMS) surgiu como um método revolucionário que permite a ressecção de lesões colorretais sem injeção submucosa. A literatura brasileira sobre essa técnica é escassa. OBJETIVO: A finalidade deste estudo foi avaliar a eficácia e segurança da técnica REMS na remoção de lesões colorretais não pediculadas em dois centros terciários brasileiros. MÉTODOS: Este estudo prospectivo foi realizado entre junho de 2016 e maio de 2017. As lesões sem tentativa de ressecção prévia, não pediculadas e sem sinais de invasão submucosa foram ressecadas pela técnica REMS. RESULTADOS: Um total de 55 pacientes com 65 lesões foram incluídos. Todas as lesões, exceto uma, foram removidas com sucesso e completamente por REMS (taxa de sucesso de 98,5%). Durante a REMS, foram observados dois casos de sangramento (3,0%). Uma paciente apresentou dor abdominal no dia seguinte à ressecção sem pneumoperitônio. Não houve perfuração ou sangramento tardio. CONCLUSÃO: Este estudo apoia os dados existentes, indicando taxas aceitáveis de sucesso técnico e baixa incidência de eventos adversos com a REMS. Os resultados deste estudo brasileiro foram consistentes com estudos internacionais prévios.

Effects of dietary menthol-rich bioactive lipid compounds on zootechnical traits, blood variables and gastrointestinal function in growing sheep.

BACKGROUND: The present study aimed at investigating the influence of 90% menthol-containing plant bioactive lipid compounds (PBLC, essential oils) on growth performance, blood haematological and biochemical profile, and nutrient absorption in sheep. Twenty-four growing Suffolk sheep were allotted into three dietary treatments: Control (without PBLC), lower dose of PBLC (PBLC-L; 80 mg/d) and higher dose of PBLC (PBLC-H; 160 mg/d). Sheep in all groups were fed meadow hay ad libitum plus 600 g/d of concentrate pellets for 28 d. RESULTS: Average daily gain was not affected by treatment. Feeding of PBLC increased hay and total feed intake per kg body weight (P < 0.05). Counts of total leucocytes, lymphocytes and monocytes were not different among treatments. However, neutrophil count decreased (P < 0.05) in PBLC-H with a similar trend in PBLC-L (P < 0.10). Concentrations of glucose, bilirubin, triglycerides, cholesterol, urea and magnesium in serum were not different among sheep fed different doses of PBLC. However, serum calcium concentration tended to increase in PBLC-H (P < 0.10) and serum concentrations of aspartate & asparagine (P < 0.01) and glutamate & glutamine (P < 0.05) increased linearly with increasing PBLC dose. In ruminal epithelia isolated from the rumen after killing, baseline conductance (G t; P < 0.05) and short-circuit current (I sc; P < 0.01) increased in both PBLC groups. Ruminal uptakes of glucose and methionine in the presence of Na+ were not affected by the dietary PBLC supplementation. In the absence of Na+, however, glucose and methionine uptakes increased (P < 0.05) in PBLC-H. In the jejunum, I sc tended to increase in PBLC-H (P < 0.10), but baseline G t was not affected. Intestinal uptakes of glucose and methionine were not influenced by PBLC in the presence or absence of Na+. CONCLUSION: The results suggest that menthol-rich PBLC increase feed intake, and passive ion and nutrient transport, the latter specifically in the rumen. They also increased serum concentrations of urea precursor amino acids and tended to increase serum calcium concentrations. Future studies will have to show whether some of these findings might be commonly linked to a stimulation of transient receptor potential (TRP) channels in the gastrointestinal tract.

Dietary supplementation of menthol-rich bioactive lipid compounds alters circadian eating behaviour of sheep.

BACKGROUND: Plant bioactive lipid compounds (PBLC), commonly known as essential oils, are increasingly evaluated as feed additives in ruminants due to beneficial effects on animal performance and health; however, there is no study evaluating circadian eating behaviour in ruminants. Altered eating behaviour may be implicated in changes of feed intake in ruminants. Therefore, the present study investigated the influence of menthol-rich PBLC on circadian eating behaviour in 24 growing sheep that were equally divided into three treatments, control (without PBLC), a lower dose (80 mg/d) or a higher dose (160 mg/d) of PBLC. Daily doses of PBLC were supplied with 600 g/d of concentrates fed in three equal portions at 07:00, 11:00 and 15:00 h for 4 weeks, whereas, meadow hay was fed ad libitum. RESULTS: The eating behaviour recorded by an automatic transponder-operated feeding system revealed that daily eating time and feeder visits increased with increasing doses of PBLC. The circadian distribution of eating time and feeder visits (with 1-h resolution) was influenced by the treatment. Eating time during concentrate-offering hours and between concentrate-offering hours increased or tended to increase linearly with greater concentrations of PBLC. Feeder visits did not change significantly during concentrate-offering hours, but were greater in the PBLC groups compared with the control between concentrate-feeding hours. Average length of the longest meals (5th percentile) decreased due to PBLC feeding. Daily feed intake was greater in the PBLC groups than the control. CONCLUSIONS: Menthol-rich PBLC in the applied dose range stimulate circadian eating behaviour, which cannot only be attributed to their presence during concentrate feeding hours, but persist during post-concentrate feeding hours.

Dietary Bioactive Lipid Compounds Rich in Menthol Alter Interactions Among Members of Ruminal Microbiota in Sheep.

This study aimed to investigate the effects of two practically relevant doses of menthol-rich plant bioactive lipid compounds (PBLC) on fermentation, microbial community composition, and their interactions in sheep rumen. Twenty-four growing Suffolk sheep were divided into three treatments and were fed hay ad libitum plus 600 g/d of concentrate containing no PBLC (Control) or PBLC at low dose (80 mg/d; PBLC-L) or high dose (160 mg/d; PBLC-H). After 4 weeks on the diets, samples of ruminal digesta were collected and analyzed for short-chain fatty acid (SCFA), ammonia, and microbiota; microbiota being analyzed in the solid and the liquid digesta fractions separately. Ruminal SCFA and ammonia concentrations were not affected by the PBLC treatments. The microbiota in the solid fraction was more diverse than that in the liquid fraction, and the relative abundance of most taxa differed between these two fractions. In the solid fraction, phylogenetic diversity increased linearly with increased PBLC doses, whereas evenness (lowest in PBLC-L) and Simpson diversity index (greatest in PBLC-H) changed quadratically. In the liquid fraction, however, the PBLC supplementation did not affect any of the microbial diversity measurements. Among phyla, Chloroflexi (highest in PBLC-L) and unclassified_bacteria (lowest in PBLC-L) were altered quadratically by PBLC. Lachnospiraceae, Bacteroidaceae (increased linearly), BS11 (increased in PBLC-L), Christensenellaceae (decreased in PBLC treatments), and Porphyromonadaceae (increased in PBLC treatments) were affected at the family level. Among genera, Butyrivibrio increased linearly in the solid fraction, YRC22 increased linearly in the liquid fraction, whereas Paludibacter increased and BF311 increased linearly with increasing doses of PBLC in both fractions. The PBLC treatments also lowered methanogens within the classes Thermoplasmata and Euryarchaeota. Correlation network analysis revealed positive and negative correlations among many microbial taxa. Differential network analysis showed that PBLC supplementation changed the correlation between some microbial taxa and SCFA. The majority of the predicted functional features were different between the solid and the liquid digesta fractions, whereas the PBLC treatments altered few of the predicted functional gene categories. Overall, dietary PBLC treatments had little influence on the ruminal fermentation and microbiota but affected the associations among some microbial taxa and SCFA.

Comprehensive comparison of pore-scale models for multiphase flow in porous media.

Multiphase flows in porous media are important in many natural and industrial processes. Pore-scale models for multiphase flows have seen rapid development in recent years and are becoming increasingly useful as predictive tools in both academic and industrial applications. However, quantitative comparisons between different pore-scale models, and between these models and experimental data, are lacking. Here, we perform an objective comparison of a variety of state-of-the-art pore-scale models, including lattice Boltzmann, stochastic rotation dynamics, volume-of-fluid, level-set, phase-field, and pore-network models. As the basis for this comparison, we use a dataset from recent microfluidic experiments with precisely controlled pore geometry and wettability conditions, which offers an unprecedented benchmarking opportunity. We compare the results of the 14 participating teams both qualitatively and quantitatively using several standard metrics, such as fractal dimension, finger width, and displacement efficiency. We find that no single method excels across all conditions and that thin films and corner flow present substantial modeling and computational challenges.

Clinical and endoscopic aspects of metastases to the gastrointestinal tract.

BACKGROUND: Studies that describe metastases to the gastrointestinal (GI) tract are restricted to small case series. An increase in the frequency of this condition is expected, so it would be useful to better characterize the endoscopic aspects of metastasis to the GI tract. The aims of this study were to describe the frequency and endoscopic features of the lesions, and to analyze the survival rate after diagnosis of metastasis. METHODS: This was a retrospective, single-center, observational study, conducted between 2009 and 2017. Patients with metastasis to the GI tract were included. RESULTS: 95 patients were included. Melanoma (25.3 %), lung (15.8 %), and breast (14.7 %) were the most frequent primary tumors. The most common endoscopic presentation was a solitary, ulcerated lesion in the gastric body. Conventional biopsy was diagnostic in 98.9 % of the cases. The mean and median survival rates were 13.3 months (95 % confidence interval [CI] 8.2 - 18.3) and 4.7 months (95 %CI 3.7 - 5.6), respectively. Palliative treatment with chemo- and/or radiotherapy after the diagnosis of the metastasis was related to a higher survival rate. CONCLUSIONS: Melanoma, lung, and breast cancer were the most common primary tumors to metastasize to the GI tract. The endoscopic features could not predict the primary site of the tumor. The finding of metastasis in the GI tract is related to the final stage of the cancer disease but patients who received palliative treatment with chemo- and/or radiotherapy after diagnosis of GI metastasis had higher survival rates.

Comparison of the pull and introducer percutaneous endoscopic gastrostomy techniques in patients with head and neck cancer.

BACKGROUND AND STUDY AIMS: Percutaneous endoscopic gastrostomy (PEG) in head and neck cancer (HNC) patients is associated with higher complication and mortality rates when compared to a general patient population. The pull technique is still the preferred technique worldwide but it has some limitations. The aim of this study is to compare the pull and introducer PEG techniques in patients with HNC. PATIENTS AND METHODS: This study is based on a retrospective analysis of a prospectively collected database of 309 patients with HNC who underwent PEG in the Cancer Institute of São Paulo. RESULTS: The procedure was performed with the standard endoscope in 205 patients and the introducer technique was used in 137 patients. There was one procedure-related mortality. Age, sex and albumin level were similar in both groups. However in the introducer technique group, patients had a higher tumor stage, a lower Karnofsky status, and presented more frequently with tracheostomy and trismus. Overall, major, minor, immediate and late complications and 30-day mortality rates were similar but the introducer technique group presented more minor bleeding and tube dysfunctions. CONCLUSION: The push and introducer PEG techniques seem to be both safe and effective but present different complication profiles. The choice of PEG technique in patients with HNC should be made individually.

Adverse events of self-expandable esophageal metallic stents in patients with long-term survival from advanced malignant disease.

BACKGROUND AND AIMS: Self-expandable metallic stents are considered the best palliative treatment of dysphagia for patients with advanced esophageal cancer. Adverse events (AEs) are a major concern, especially in patients with better prognosis and longer survival. The present study aimed to evaluate the AEs of patients who survived longer than 6 months with esophageal stents in place. METHODS: This is a retrospective analysis of a prospectively collected database including all patients submitted to esophageal stent placement for the palliation of malignant diseases during the period from February 2009 to February 2014 at a tertiary care academic center who had stents longer than 6 months. RESULTS: Sixty-three patients were included. Mean follow-up was 10.7 months. Clinical success was achieved in all patients, and the median stent patency was 7.1 months. AEs occurred in 40 patients (63.5%), totaling 62 AEs (mean, 1.5 AEs per patient). Endoscopic management of AEs was successful in 84.5% of cases, with a mean of 1.6 reinterventions per patient. The univariate analysis revealed that performance status, age, and post-stent radiotherapy presented a trend to higher risk of AEs. The multivariate analysis revealed that only performance status was associated with AEs (P = .025; hazard ratio, 4.1). CONCLUSIONS: AEs are common in patients with long-term esophageal stenting for malignancy. However, AEs were not related to higher mortality rate, and most AEs could be successfully managed by endoscopy. Only performance status was a risk factor for AEs. Our data suggest that metallic stenting is a valid option for the treatment of malignant esophageal conditions, even when survival longer than 6 months is expected.

Diagnostic accuracy of probe-based confocal laser endomicroscopy in Lugol-unstained esophageal superficial lesions of patients with head and neck cancer.

BACKGROUND AND AIMS: Surveillance programs of patients with head and neck cancer (HNC) detect synchronous or metachronous esophageal squamous cell carcinoma (ESCC) in up to 15% of patients. Noninvasive, probe-based confocal laser endomicroscopy (pCLE) technique may improve the diagnosis allowing acquisition of high-resolution in vivo images at the cellular and microvascular levels. The aim of this study was to evaluate the accuracy of pCLE for the differential diagnosis of nonneoplastic and neoplastic Lugol-unstained esophageal lesions in patients with HNC. METHODS: Twenty-seven patients with HNC who exhibited Lugol-unstained esophageal lesions at surveillance endoscopy were prospectively included for pCLE. Diagnostic pCLE was followed by subsequent biopsies or endoscopic resection of suspected lesions. A senior pathologist was blinded to the pCLE results. RESULTS: Patients mean age was 59 years (SD = 8.8) and 70.4% were men. All patients were smokers, and 22 patients (81.5%) had a history of alcohol consumption. The locations of HNC were oral cavity (n = 13), larynx (n = 10), and pharynx (n = 4). Thirty-seven lesions in 27 patients were studied. The final diagnoses were ESCC in 17 patients and benign lesions in 20 patients. Sensitivity, specificity, and accuracy of pCLE for the histologic diagnosis of ESCC in patients with HNC were 94.1%, 90.0%, and 91.9%, respectively. CONCLUSIONS: First, pCLE is highly accurate for real-time histology of Lugol-unstained esophageal lesions in patients with HNC. Second, pCLE may alter the management of patients under surveillance for ESCC, guiding biopsies and endoscopic resection, avoiding further diagnostic workup or therapy of benign lesions.

Droplet fragmentation: 3D imaging of a previously unidentified pore-scale process during multiphase flow in porous media.

Using X-ray computed microtomography, we have visualized and quantified the in situ structure of a trapped nonwetting phase (oil) in a highly heterogeneous carbonate rock after injecting a wetting phase (brine) at low and high capillary numbers. We imaged the process of capillary desaturation in 3D and demonstrated its impacts on the trapped nonwetting phase cluster size distribution. We have identified a previously unidentified pore-scale event during capillary desaturation. This pore-scale event, described as droplet fragmentation of the nonwetting phase, occurs in larger pores. It increases volumetric production of the nonwetting phase after capillary trapping and enlarges the fluid-fluid interface, which can enhance mass transfer between the phases. Droplet fragmentation therefore has implications for a range of multiphase flow processes in natural and engineered porous media with complex heterogeneous pore spaces.