A single‐step laser scribing process is used to pattern nanostructured electrodes on paper‐based devices. The facile and low‐cost technique eliminates the need for chemical reagents or controlled ...conditions. This process involves the use of a CO2 laser to pyrolyze the surface of the paperboard, producing a conductive porous non‐graphitizing carbon material composed of graphene sheets and composites with aluminosilicate nanoparticles. The new electrode material was extensively characterized, and it exhibits high conductivity and an enhanced active/geometric area ratio; it is thus well‐suited for electrochemical purposes. As a proof‐of‐concept, the devices were successfully employed for different analytical applications in the clinical, pharmaceutical, food, and forensic fields. The scalable and green fabrication method associated with the features of the new material is highly promising for the development of portable electrochemical devices.
Electrochemistry on paperboard: A simple, scalable fabrication of nanostructured electrochemical paper‐based analytical devices using a CO2 laser and paperboard is presented. The method does not require additional reagents or control of the fabrication environment.
Space‐borne instruments can measure river water surface elevation, slope, and width. Remote sensing of river discharge in ungauged basins is far more challenging, however. This work investigates the ...estimation of river discharge from simulated observations of the forthcoming Surface Water and Ocean Topography (SWOT) satellite mission using a variant of the classical variational data assimilation method “4D‐Var.” The variational assimilation scheme simultaneously estimates discharge, river bathymetry, and bed roughness in the context of a 1.5 D full Saint‐Venant hydraulic model. Algorithms and procedures are developed to apply the method to fully ungauged basins. The method was tested on the Po and Sacramento Rivers. The SWOT hydrology simulator was used to produce synthetic SWOT observations at each overpass time by simulating the interaction of SWOT radar measurements with the river water surface and nearby land surface topography at a scale of approximately 1 m, thus accounting for layover, thermal noise, and other effects. SWOT data products were synthesized by vectorizing the simulated radar returns, leading to height and width estimates at 200 m increments along the river centerlines. The ingestion of simulated SWOT data generally led to local improvements on prior bathymetry and roughness estimates which allowed the prediction of river discharge at the overpass times with relative root mean squared errors of 12.1% and 11.2% for the Po and Sacramento Rivers, respectively. Nevertheless, equifinality issues that arise from the simultaneous estimation of bed elevation and roughness may prevent their use for different applications, other than discharge estimation through the presented framework.
Key Points
River discharge is estimated using synthetic remote sensing measurements from the forthcoming SWOT mission without any in situ observation
2D SWOT radar measurements are simulated and mapped onto river centerlines, producing realistic errors, temporal, and spatial sampling
Discharge accuracy was 12.1% and 11.2% on the Po and Sacramento Rivers, respectively, illustrating potential for ungauged basins
Introduction
There are no definitive data concerning the ideal configuration of ileocolic anastomosis. Aim of this study was to identify perioperative risk factors for anastomotic leak and for 60-day ...morbidity and mortality after ileocolic anastomoses (stapled vs handsewn).
Materials and methods
This is a STROBE-compliant study. Demographic and surgical data were gathered from patients with an ileocolic anastomosis performed between November 2010 and September 2016 at a tertiary hospital. Anastomoses were performed using standardised techniques. Independent risk factors for anastomotic leak, complications and mortality were assessed.
Results
We included 477 patients: 53.7% of the anastomoses were hand sewn and 46.3% stapled. Laterolateral anastomosis was the most common configuration (93.3%). Anastomotic leak was diagnosed in 8.8% of patients and 36 were classified as major anastomotic leak (7.5%). In the multivariate analysis, male sex (P = 0.014, odds ratio, OR, 2.9), arterial hypertension (P = 0.048, OR 2.29) and perioperative transfusions (P < 0.001, OR 2.4 per litre) were independent risk factors for major anastomotic leak. The overall 60-day complication rate was 27.3%. Male sex (31.3% vs female 22.3%, P = 0.02, OR 1.7), diabetes (P = 0.03 OR 2.0), smoking habit (P = 0.04, OR 1.8) and perioperative transfusions (P < 0.001, OR 3.3 per litre) were independent risk factors for postoperative morbidity. The 60-day-mortality rate was 3.1% and no significant risk factors were identified.
Conclusion
Anastomotic leak after ileocolic anastomosis is a relevant problem. Male sex, arterial hypertension and perioperative transfusions were associated with major anastomotic leak. Conversion to open surgery was more frequently associated with perioperative death.
Aim
Many surgical techniques are available for the treatment of rectovaginal fistula (RVF). There is hitherto little information on its treatment by biological mesh interposition. The aim of the ...present study was to analyse our results of RVF treatment using biological mesh interposition.
Method
Patients with RVF undergoing biological mesh interposition were identified. Success was defined by the absence of a diverting stoma and/or any vaginal discharge of faeces, flatus or mucous discharge.
Results
Ten women median age 39 (24.5–65) years were included. Nine (90%) had recurrent RVF, and the median number of previous attempts at closure was 2.5 (0−8). The main cause of RVF was Crohn's disease (40%). All patients had faecal diversion. No intra‐operative complications occurred from mesh interposition. Seven (70%) patients developed postoperative morbidity which was major (Dindo III) in two (20%). The primary success rate was 20% (2/10) but final success rate was achieved in 70% after reoperation with other procedures at 11.1 (2.7−13.1) months of follow‐up.
Conclusion
The study has shown disappointing results with biological mesh interposition for RVF with a healing rate lower than achieved by gracilis muscle interposition.
FireStem2D, a software tool for predicting tree stem heating and injury in forest fires, is a physically-based, two-dimensional model of stem thermodynamics that results from heating at the bark ...surface. It builds on an earlier one-dimensional model (FireStem) and provides improved capabilities for predicting fire-induced mortality and injury before a fire occurs by resolving stem moisture loss, temperatures through the stem, degree of bark charring, and necrotic depth around the stem. We present the results of numerical parameterization and model evaluation experiments for FireStem2D that simulate laboratory stem-heating experiments of 52 tree sections from 25 trees. We also conducted a set of virtual sensitivity analysis experiments to test the effects of unevenness of heating around the stem and with aboveground height using data from two studies: a low-intensity surface fire and a more intense crown fire. The model allows for improved understanding and prediction of the effects of wildland fire on injury and mortality of trees of different species and sizes.
The Surface Water and Ocean Topography (SWOT) satellite mission planned for launch in 2020 will map river elevations and inundated area globally for rivers >100 m wide. In advance of this launch, we ...here evaluated the possibility of estimating discharge in ungauged rivers using synthetic, daily “remote sensing” measurements derived from hydraulic models corrupted with minimal observational errors. Five discharge algorithms were evaluated, as well as the median of the five, for 19 rivers spanning a range of hydraulic and geomorphic conditions. Reliance upon a priori information, and thus applicability to truly ungauged reaches, varied among algorithms: one algorithm employed only global limits on velocity and depth, while the other algorithms relied on globally available prior estimates of discharge. We found at least one algorithm able to estimate instantaneous discharge to within 35% relative root‐mean‐squared error (RRMSE) on 14/16 nonbraided rivers despite out‐of‐bank flows, multichannel planforms, and backwater effects. Moreover, we found RRMSE was often dominated by bias; the median standard deviation of relative residuals across the 16 nonbraided rivers was only 12.5%. SWOT discharge algorithm progress is therefore encouraging, yet future efforts should consider incorporating ancillary data or multialgorithm synergy to improve results.
Key Points:
SWOT discharge algorithms were tested on synthetic observations for 19 rivers
Algorithms accurately characterized temporal dynamics of river discharge
At least one algorithm estimated discharge to <35% relative RMSE on 14/16 of nonbraided rivers
Background
Assessment of the entire small bowel is advocated during Crohn’s disease (CD) surgery, as intraoperative detection of new lesions may lead to change in the planned procedure. The aim of ...this study was to evaluate the inter-observer variability in the assessment of extent and severity of CD at the small bowel laparoscopic “walkthrough”.
Methods
A survey on laparoscopic assessment of the small bowel in patients with CD, including items adapted from the MREnterography or ultrasound in Crohn's disease (METRIC) study and from the classification of severity of mesenteric disease was developed by an invited committee of colorectal surgeons. Anonymous laparoscopic videos demonstrating the small bowel “walkthrough” in ileocolonic resection for primary and recurrent CD were distributed to the committee members together with the anonymous survey. The primary outcome was the rate of inter-observer variability on assessment of strictures, dilatations, complications and severity of mesenteric inflammation.
Results
12 assessors completed the survey on 8 small bowel walkthrough videos. The evaluation of the small bowel thickening and of the mesenteric fat wrapping were the most reliable assessments with an overall agreement of 87.1% (
k
= 0.31; 95% CI − 0.22, 0.84) and 82.7% (
k
= 0.35; 95% CI − 0.04, 0.73), respectively. The presence of strictures and pre-stenotic dilatation demonstrated agreement of 75.2% (
k
= 0.06: 95% CI − 0.33, 0.45) and 71.2% (
k
= 0.33; 95% CI 0.15, 0.51), respectively. Evaluation of fistulae had an overall agreement of 75.3%, while there was a significant variation in the evaluation of mild, moderate and severe mesenteric disease with overall agreement ranging from 33.3 to 100%.
Conclusion
Laparoscopic assessment of the small bowel thickening and of the presence of mesenteric fat wrapping is reliable for the intraoperative evaluation of CD with high inter-rater agreement. There is significant heterogeneity in the assessment of the severity of the mesenteric disease involvement.
Introduction
To explore the reported variability in the surgical management of ileocolonic Crohn’ s disease and identify areas of standard practice, we present this study which aims to assess how ...different colorectal surgeons with a subspecialty interest in inflammatory bowel disease (IBD) surgery may act in different clinical scenarios of ileocolonic Crohn’s disease.
Methods
Anonymous videos demonstrating the small bowel walkthrough and anonymised patients’ clinical data, imaging and pathological findings were distributed to the surgeons using an electronic tool. Surgeons answered on operative strategy, bowel resections, management of small bowel mesentery, type of anastomosis and use of stomas.
Results
Eight small bowel walkthrough videos were registered and 12 assessors completed the survey with a questionnaire completion rate of 87.5%. There was 87.7% agreement in the need to perform an ileocolonic resection. However, the agreement for the need to perform associated surgical procedures such as strictureplasties or further bowel resections was only 57.4%. When an anastomosis was fashioned, the side to side configuration was the most commonly used. The preferred management of the mesentery was dissection close to the bowel.
Conclusions
The decision on the main procedure to be performed had a high agreement amongst the different assessors, but the treatment of multifocal disease was highly controversial, with low agreement on the need for associated procedures to treat internal fistulae and the use of strictureplasties. At the same time, there was significant heterogeneity in the decision on when to anastomose and when to fashion an ileostomy.
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