Multiple Plastic Research Articles

Adaptation of vestibulo-ocular and optokinetic reflexes after massed and spaced vestibulo-ocular motor learning

Although the superiority of spaced training over massed training has been established in many forms of learning, the learning efficacy between the two with respect to time efficiency may not be simply compared because a longer total duration of learning is required in spaced training than massed training due to spacing intervals intervening between training sessions in the former. The purpose of the present study was to evaluate the differences in the adaptation of the vestibulo-ocular reflex (VOR) and optokinetic reflex (OKR) after visuo-vestibular training, and to investigate the efficacy of spaced and massed training in mice. Associative visuo-vestibular stimulation was applied to induce VOR and OKR motor learning. Training paradigms were categorized into five groups according to the duration of the spacing interval, keeping the total training time including spacing equal in all training paradigms. Both gain-up VOR training, which increased VOR gain and gain-down VOR training, which decreased VOR gain, increased OKR gain in the massed and spaced learning paradigms. While the increment in OKR gain after gain-up and gain-down training was maintained at 48 h after the end of the last training session, the change in VOR gain by gain-up or gain-down training recovered gradually after training. The OKR adaptation was still in progress during the spacing interval, and the amount of gain increase was greater with longer spacing interval. On the other hand, the VOR gain change after gain-up and gain-down training substantially recovered during the spacing interval. In conclusion, the present study, using learning paradigms with same total duration of training, demonstrated that the spacing effect was more robust in the adaptation of OKR than that of VOR, and the learning effect was maintained longer in OKR than in VOR. These differences in the adaptation of VOR and OKR following identical training conditions suggest that multiple plasticity mechanisms may be differentially involved in the gaze stabilization circuitry.

Trash-to-fuel: Converting municipal waste into transportation fuels by pyrolysis

SummaryIn daily life humankind is producing a significant amount of garbage, creating a great environmental concern. However, garbage consists of high amounts of carbon based materials, making it a very useful resource. An easy way to use it is to produce transport fuels obtained through pyrolysis. Multiple plastic waste materials were investigated here. Thermogravimetric analysis (TGA) of individual polymers shows that almost complete conversion could be achieved. More than 70% liquid fuels were derived from pyrolysis of polypropylene, polystyrene at 450°C, and low-/high-density polyethylene at 500°C. Using gas chromatography/high-resolution mass spectrometry (GC/HR-MS) allows studying the thermal transformation and proposing a mechanism. An examination of carbon number distribution reveals the potential of plastic liquid fuels, which can be used as an alternative to partial substitution of fossil-fuel-derived gasoline and diesel fuel and also provides a final use of polymer materials, which otherwise would be deposited on waste dumps.

Efficacy and Safety of Peroral Pancreatoscopy Through the Fistula Created by Endoscopic Ultrasound-Guided Pancreaticogastrostomy.

Endoscopic ultrasound/endosonography-guided pancreaticogastrostomy (EUS-PGS) is a useful alternative when endoscopic retrograde pancreatography is difficult. Recently, many procedures, including peroral pancreatoscopy (POPS), have been performed through the mature fistula (MF) created by EUS-PGS. We evaluate the efficacy and safety of POPS to diagnose and treat pancreatic ductal stricture/pancreato-jejunal anastomotic stricture (PDS/PJAS) through the MF. Twenty patients underwent EUS-PGS; 13 of these underwent POPS through the MF at Juntendo University Hospital. All patients were studied retrospectively in terms of technical and clinical success rates and adverse events (AEs). The technical and clinical success rates of EUS-PGS were 95% and 100%. The early and late AEs rates were 20% and 15%. The technical success rate of POPS was 100%, with one AE. Biopsy of PDS/PJAS under POPS guidance revealed recurrent/residual intrapapillary mucinous adenoma (3 patients) and benign fibrotic stricture (10 patients). In the latter patients, multiple plastic stents were placed to dilate PDS/PJAS. Four patients with improvement of PDS/PJAS were stent free, but the remaining patients were not yet. Endoscopic ultrasound/endosonography-guided pancreaticogastrostomy and various procedures (including POPS) performed through the MF are feasible and effective and can diagnose and treat PDS/PJAS with acceptable AEs rates.

A physical mechanism of heterogeneity and micro-metastasis in stem cells, cancer cells, and cancer stem cells.

Heterogeneity is ubiquitous in stem cells (SC), cancer cells (CS), and cancer SC (CSC). This heterogeneity manifests in the form of diverse sub-populations of SC, CS, and CSC with self-renewal and unique regeneration capacity. Moreover, the progeny of CSC possess multiple plasticity and cancerous characteristics. Many studies have demonstrated that cancer heterogeneity is among the greatest obstacles to successful anti-cancer therapy. This leads to incomplete therapy and transitory efficacy. Furthermore, numerous micro-metastases lead to the spread of tumor cells widely across the body; this is the beginning of metastasis. Epigenetic processes (DNA methylation and histone remodification) represent sources of heterogeneity. In this study, we develop a mathematical model to quantify the heterogeneity of SC, CS, and CSC, taking into consideration both genetic and epigenetic effects. We reveal the roles and physical mechanisms of heterogeneity in SC, CSC, and cancer cells. Under the adiabatic regime (relatively fast regulatory binding and effective coupling among genes), seven native states (SC, CSC, cancer, premalignant, normal, lesion, and hyperplasia) emerge. Under the non-adiabatic regime (relatively slow regulatory binding and effective weak coupling among genes), SC, CS, CSC, and differentiated states emerge and become diffusive, partially explaining the origin of heterogeneity. In other words, slow regulatory binding that mimics epigenetic effects can give rise to heterogeneity. Moreover, we calculated the entropy production rate and Fano factor, which can be used to quantify the thermodynamic cost and the degrees of the variations or the fluctuations as the parameter ω (representing the speed of regulatory binding/unbinding relative to the synthesis/degradation) changes. Elucidating the origins of heterogeneity and the dynamical relationships between intra-tumoral cells has a clear clinical significance and will improve the understanding of the cellular basis of treatment response, therapeutic resistance, and cancer metastasis.

Fully Covered Self-expanding Stents are Cost-effective at Remediating Biliary Strictures in Patients With Chronic Pancreatitis

Benign biliary strictures (BBS) develop in up to 10% to 30% of patients with chronic pancreatitis (CP).1 Endoscopic endoprosthetics via endoscopic retrograde cholangiopancreatography (ERCP) has become the standard of care for remediating these strictures. Seventy percent to eighty percent of these strictures resolve with sequential or concurrent placement of multiple plastic stents (MPS).1,2 More recently, placement of fully covered self-expanding metal stents (FCSEMS) have been shown to have similar outcomes as MPS.3-6 FCSEMS provide a larger radial diameter and require fewer procedures, but may have drawbacks, including a higher risk of migration, cholecystitis, delamination, and tissue ingrowth. A recent study demonstrated that FCSEMS with a 12-month indwell had similar outcomes to MPS with fewer ERCP needed.7 However, the cost-effectiveness of either strategy for managing BBS has not been assessed previously nor has the impact of additional reimbursement to cover the cost of FCSEMS on the cost-effectiveness of FCSEMS utilization.

Metal versus plastic stents in the management of benign biliary strictures: systematic review and meta-analysis of randomized controlled trials.

Benign biliary strictures (BBS) are usually treated with endoscopic retrograde cholangiopancreatography (ERCP) with the placement of multiple plastic stents (MPS) or a covered self-expandable metal stent (CSEMS). In this meta-analysis, we compared the efficacy and safety of MPS and CSEMS in the management of BBS. We reviewed several databases from inception to 28 April 2021 to identify RCTs that compared MPS with CSEMS in the management of BBS. Our outcomes of interest were stricture resolution, stricture recurrence, adverse events, stent migration and mean number of ERCPs to achieve stricture resolution. Data were analyzed using a random-effects model. We included eight RCTs with 524 patients. We found no significant difference in the rate of stricture resolution (risk ratio, 1.02; 95% CI, 0.96-1.10), stricture recurrence (risk ratio, 1.68; 95% CI, 0.72-3.88) or adverse events (risk ratio, 1.17; 95% CI, 0.73-1.87) between groups. Mean number of ERCPs was significantly lower in the CSEMS group (SMD, -1.99; 95% CI, -3.35 to -0.64). The rate of stent migration was significantly higher in the CSEMS group. CSEMS are comparable in efficacy and safety to MPS in the management of BBS but require fewer ERCPs to achieve stricture resolution.

Observations on additive plasticity in the logarithmic strain space at excessive strains

Additive plasticity in the logarithmic strain space is compared to multiplicative plasticity for various loading cases including coaxial and non-coaxial plastic deformations. Even though both finite plasticity approaches are based on total Lagrangian descriptions, the former is popular due to its inherent similarity to the infinitesimal theory and its easy extensibility. However, since its introduction several limitations of additive plasticity in the logarithmic strain space have been discovered. In this study, these problems such as stress rotation and softening are considered, revealing that fundamental differences compared to multiplicative plasticity occur for non-coaxial plastic deformations. We focus in particular on the observed softer response of the additive based approach, which is analysed in depth using three numerical examples including two well-known benchmarks for finite plasticity. By means of these finite element simulations the softer and possibly even localising response of additive plasticity in the logarithmic strain space is confirmed.

A review of biodegradable thermoplastic starches, their blends and composites: recent developments and opportunities for single-use plastic packaging alternatives

This review article effectively analyses the effect of multiple plasticizers, compatibilizers, and essential oils on plasticized starch in the preparation of thermoplastic starch-based biodegradable blends and composites.

Intrinsically stretchable carbon nanotube synaptic transistors with associative learning ability and mechanical deformation response

Stretchable synaptic transistors with the ability to emulate multiplexed neural signal transmission is an important step toward mimicking complex brain activities in bionic memory sensors, intelligent soft robots, and skin electronics. The reports about stretchable artificial synaptic transistors are very limited and further exploration is urgently required. In this work, intrinsically stretchable carbon nanotube synaptic transistors (IS-CNT-STs) with poly (urea-urethane) dielectric have been realized. The synaptic characteristics and the synaptic mechanism have been analysed. Synaptic functions of the biological synapses including excitatory and inhibitory behaviours, short-term plasticity, and filtering characteristic are successfully emulated in the IS-CNT-STs. Moreover, the IS-CNT-STs have exhibited excellent mechanical stretchability even after experiencing large stretching deformation. After stretched by 50% strain, and even after 400 stretching cycles by 25% strain, both the transistor characteristics and the synaptic functions remain correctly. The realized IS-CNT-STs possess low operating voltage, multiple synaptic plasticity, and mechanical deformation response. The demonstrations indicate their capability to work in the stretchable artificial neuromorphic systems.

Fishing line assisted endoscopic placement of multiple plastic biliary stents for unresectable malignant hilar biliary obstruction: a retrospective study

Background and aimsStent migration is one of the most common complications during the placement of multiple plastic biliary stents (MPBS) under endoscopy. This study aims to evaluate the feasibility and efficiency of the fishing line assisted (FLA) method for preventing the complication.Methods Patients with unresectable malignant hilar biliary obstruction (MHBO) who undergone endoscopic placement of MPBS using the FLA or conventional method from May 2018 to April 2021 in our center were enrolled in the study. The endpoints of this study were the stent migration rate, technical success rates, adverse events rates, times of stent migration, and the procedure time.ResultsFLA group (N = 19) and conventional group (N = 22) had similar baseline characteristics of the patients. The technical success rates (100% vs. 95.5%; P > 0.05), ERCP-related adverse events rates (5.3% vs. 4.5%; P > 0.05), and the stent-related adverse events rates (0% vs. 4.5%; P > 0.05) were no significant differences between the FLA and conventional groups. MPBS inserted using the conventional method consumed more time (median, 33.9 min vs. 15.6 min; P < 0.05) method and increased the times of stent migration (median, 3 times vs. 0 times; P < 0.05) than using the FLA method. Even if no statistical difference was detected in the stent migration rate between groups, this rate was lower in the FLA group than the conventional group (0% vs. 13.6%; P > 0.05).ConclusionsFLA method is an effective technique for MPBS implantation to prevent stent migration during endoscopic retrograde cholangiography (ERCP). The method should be applied to patients with unresectable MHBO who need to place MPBS.

The Comparison of Endoscopic Biliary Drainage in Malignant Hilar Obstruction by Cholangiocarcinoma: Bilateral Metal Stents versus Multiple Plastic Stents.

Background/AimsFor the management of hilar malignant biliary obstruction (HMBO), endoscopic biliary drainage (EBD) is preferred over percutaneous transhepatic biliary drainage (PTBD) because of its convenience. However, there is no established guideline for malignant hilar obstruction that requires multiple stenting. In this study, we compared the efficacy of bilateral metal stents (BMS) versus multiple plastic stents (MPS).MethodsIn this retrospective study, we analyzed 102 patients who underwent EBD with either BMS or MPS due to HMBO caused by hilar cholangiocarcinoma between 1996 and 2018 at Samsung Medical Center. We compared the successful drainage rates, cholangitis events, overall complications, mortality, and conversion rates to PTBD between the two groups.ResultsThe successful drainage rates in the BMS group and the MPS group were 71.4% (25/35) and 65.6% (44/67), respectively, with no significant difference. The MPS group had a higher cholangitis risk (hazard ratio [HR], 2.08; 95% confidence interval [CI], 1.21 to 3.58) and higher 6-month mortality (HR, 2.91; 95% CI, 1.26 to 6.71) than the BMS group. There were no significant differences in overall complications or the conversion rate to PTBD between the groups.ConclusionsIn patients with malignant HMBO, the BMS group showed better outcomes in terms of the cholangitis rate and 6-month mortality than the MPS group. Therefore, if possible, bilateral metal stenting is recommended for HMBO caused by hilar cholangiocarcinoma.

Effects of stacking fault energy on the deformation behavior of CoNiCrFeMn high-entropy alloys: A molecular dynamics study

Tailoring stacking fault energy (SFE) is an effective way for enhancing mechanical properties of certain high entropy alloys (HEAs) such as the prototype Cantor alloy. However, the underlying mechanism, especially the atomistic origins for the enhanced plasticity and strength, is still unclear. In this work, we performed molecular dynamics simulations to investigate the mechanical behavior of CoxNi40−xCr20Fe20Mn20 (x = 10, 20, and 30 at. %) HEAs under tensile loading. The results show that the SFE decreases with the increase in Co concentration and favors the formation of continuous stacking fault networks on which multiple plastic deformation carriers including stacking faults, dislocations, twins, and martensitic transformation were sequentially activated. The activation and complex interaction of these multiple carriers mainly contribute to the improved plasticity, and the increased stair-rod dislocations result in the enhanced strength in Co30Ni10Cr20Fe20Mn20 HEA. The current findings may be important for the understanding of SFE effects at the atomistic scale and also shed light on designing of high-performance HEAs.

Complex Skull Fracture in a Toddler.

Complex Skull Fracture in a Toddler.

Comparison of Shifts in Skeletal Muscle Plasticity Parameters in Horses in Three Different Muscles, in Answer to 8 Weeks of Harness Training.

Training-induced follow-up of multiple muscle plasticity parameters in postural stability vs. locomotion muscles provides an integrative physiological view on shifts in the muscular metabolic machinery. It can be expected that not all muscle plasticity parameters show the same expression time profile across muscles. This knowledge is important to underpin results of metabolomic studies. Twelve non-competing Standardbred mares were subjected to standardized harness training. Muscle biopsies were taken on a non-training day before and after 8 weeks. Shifts in muscle fiber type composition and muscle fiber cross-sectional area (CSA) were compared in the m. pectoralis, the m. vastus lateralis, and the m. semitendinosus. In the m. vastus lateralis, which showed most pronounced training-induced plasticity, two additional muscle plasticity parameters (capillarization and mitochondrial density) were assessed. In the m. semitendinosus, additionally the mean minimum Feret's diameter was assessed. There was a significant difference in baseline profiles. The m. semitendinosus contained less type I and more type IIX fibers compatible with the most pronounced anaerobic profile. Though no baseline fiber type-specific and overall mean CSA differences could be detected, there was a clear post-training decrease in fiber type specific CSA, most pronounced for the m. vastus lateralis, and this was accompanied by a clear increase in capillary supply. No shifts in mitochondrial density were detected. The m. semitendinosus showed a decrease in fiber type specific CSA of type IIAX fibers and a decrease of type I fiber Feret's diameter as well as mean minimum Feret's diameter. The training-induced increased capillary supply in conjunction with a significant decrease in muscle fiber CSA suggests that the muscular machinery models itself toward an optimal smaller individual muscle fiber structure to receive and process fuels that can be swiftly delivered by the circulatory system. These results are interesting in view of the recently identified important fuel candidates such as branched-chain amino acids, aromatic amino acids, and gut microbiome-related xenobiotics, which need a rapid gut–muscle gateway to reach these fibers and are less challenging for the mitochondrial system. More research is needed with that respect. Results also show important differences between muscle groups with respect to baseline and training-specific modulation.

Plastic deformation and strengthening mechanism of FCC/HCP nano-laminated dual-phase CoCrFeMnNi high entropy alloy

FCC-structured CoCrFeMnNi high entropy alloy (HEA) has attracted abroad interests for years because of its excellent mechanical properties, except for strength. Recent experiments have reported a kind of nano-laminated dual-phase (NLDP) FCC/HCP structure that can strengthen the HEA. However, it is still unknown why the HEA can be strengthened by this kind of NLDP structure. Here, we employ molecular dynamics simulations to study the atomistic strengthening mechanism of the NLDP HEA. Dislocation-assisted multiple plastic deformation mechanisms in both FCC and HCP single phase HEAs are observed, and amorphization is also found in the plasticity of HCP phase, which are consistent with the previous experimental characterizations. The HCP phase possesses higher strength because of its higher stacking fault energy, higher Peierls–Nabarro stress and less active dislocation slip systems. It is also found that the introduction of HCP phase can enhance the mechanical properties, including yield stress, yield strain and plastic flow stress, of the NLDP HEAs, which also show volume fraction dependence. And the phase boundary plays crucial roles in the deformation and strengthening of the NLDP HEAs. The plastic deformation of the NLDP HEAs can be divided into two stages, i.e. stage I (plasticity only appears in FCC lamella) and stage II (plasticity in both FCC and HCP lamellas). With the increase of volume fraction, the lamella thickness of FCC matrix phase decreases, leading to continuous strengthening of yield properties and flow stress of stage I because of suppressed dislocation nucleation and confined dislocation motion in FCC matrix phase by the phase boundary. While there is no monotonous relationship between the flow stresses of stage II and the increasing volume fraction of HCP phase, which can be attributed to the competitive mechanisms between strengthening effect of phase boundary on the dislocation motion in FCC phase and softening effect of phase boundary on the dislocation motion in HCP phase. The results should be helpful for understanding the underlying physical mechanism of strengthening of HEAs with NLDP structure.

387 Plastics Surgery and the COVID-19 Pandemic: How Our Practice Has Improved as A Consequence

AimPlastic trauma cases were impacted by the COVID-19 pandemic. Multiple plastic trauma theatres were lost due to redeployment and redistribution of staff and resources. Plastic surgery was essentially left with an emergency list to manage trauma cases. This retrospective study aims to highlight the pitfalls and solutions realised during COVID times and how different strategies can be implemented should a third national lock down occur.MethodPlastic surgery data (trauma, elective) was analysed from the first national lockdown due to COVID-19 in 2020. This data was compared against plastic surgery trauma data from 2019. Theatre time, the number of trauma surgeries, anaesthetic used and delay to theatre were all analysed.ResultsThere was a 47% reduction in plastic surgery trauma cases and a 42% reduction in delay to surgery during the national lockdown (2020) when compared with data from 2019. A significant increase in the use of Local Anaesthetic (LA) and Regional Anaesthetic (RA) during COVID times with a decrease in General Anaesthetic when compared with pre-COVID data of 2019 was also identified.ConclusionsThis study identified that the majority of plastic cases could be performed under RA/LA. This would lead to decreased aerosol generating procedures (GA) thus limiting the transmission of COVID, and decreased delay to surgery and theatre time. As a third national lockdown may be on the horizon, it would be prudent to implement these strategies into current practice and by doing so optimising theatre usage and assisting in curtailing the COVID-19 transmission rate.

S3374 Plastic vs Metal Stents for Anastomotic Biliary Strictures After Orthotopic Liver Transplant (OLT)

Introduction: Biliary anastomotic stricture is the most common complication of orthotopic liver transplantation (OLT) occurring in about 20% of cases. Endoscopic stent placement across the stricture with plastic or metal stents is the first-line treatment strategy. The aim of this study is to investigate the difference between plastic and metal stents in terms of anastomotic biliary stricture resolution and adverse events. Methods: This is a retrospective study of post OLT patients who underwent ERCP over a 3-year period between 2018-2020. Out of 178 post OLT patients who underwent ERCP, 108 were excluded because of only one ERCP performed and repeat ERCP was not indicated or because ERCP was performed for indications other than anastomotic biliary strictures. Data was collected up to 3 consecutive ERCP procedures during the studied period. Results: A total of 70 patients with anastomotic biliary strictures were included in the study. ERCP was performed on a native papilla in 32 (45.7%), advanced cannulation techniques were performed in 5 (7.1%), and prophylactic pancreatic stents were placed in 6 (8.6%) cases. Plastic stents (PS) were used in 53 (75.7%) of which multiple plastic stents were used in 27 cases, whereas 17 (24.3%) cases were treated with fully covered self-expanding metal stents (FCSEMS). Average follow up duration was 2.2 (1-3) months for PS and 3.7 (2-5) months for FCSEMS (P < 0.01). Biliary strictures resolved in 21 (30.0%) patients on repeat ERCP most of which from the FCSEMS group (58.8% vs 20.8%) (P = 0.009). Plastic stents were exchanged to FCSEMS in 11 (20.8%) patients during the second ERCP follow-up. On the third ERCP during the studied period, biliary strictures resolved in 71.4% of the FCSEMS group vs 33.3% of the PS group (P = 0.03). Using multiple plastic stents instead of a single plastic stent didn’t seem to improve biliary stricture resolution rate. Two patients (2.4%) developed post-ERCP pancreatitis, both patients had a native papilla and underwent FCSEMS placement with sphincterotomy and without pancreatic duct manipulation (P = 0.06). There was no difference between the stents used in terms of post-procedural cholangitis or stent migration rates. Conclusion: FCSEMS outperformed PS with respect to the anastomotic biliary stricture resolution rate over 3 endo-therapy sessions. Post-ERCP pancreatitis, although uncommon, occurred exclusively in the FCSEMS group.

A finite deformation multiplicative plasticity model with non–local hardening for bonded geomaterials

The paper presents a finite deformation, isotropic hardening, non–associative elastic–plastic constitutive model (FD_Milan model) for describing the mechanical behavior of a wide range of bonded natural geomaterials such as stiff overconsonsolidated clays, porous soft rocks or bio–improved soils. The formulation of the model is based on the multiplicative split of the deformation gradient and on the assumption of hyperelastic behavior. To deal with the occurrence of strain localization, typically observed in this class of geomaterials, the model has been equipped with a non–local version of the hardening laws. This approach is capable of regularizing the pathological mesh dependence occurring in the post–localization regime when adopting classical plasticity models.In view of its application to practical geotechnical problems characterized by large displacements and deformations within a hydro-mechanical coupled environment, the model has been implemented in the recently developed Particle Finite Element code G–PFEM for geomechanics applications.To demonstrate the effectiveness of the numerical implementation, a series of numerical simulations has been performed considering two representative boundary value problems: the modeling of shear localization in plane strain biaxial tests and the simulation of CPTu tests in a saturated porous soil. The results of biaxial test simulations have highlighted the role of the characteristic length in controlling the thickness of the localized zone and the effect of the confining pressure in determining the pattern of shear band formation. An interesting feature emerging from the partially drained CPTu simulation results is the progressive formation of persistent shear bands, which originate from the cone tip and propagate outwards along the entire penetration depth.

Endoscopic transmural drainage tailored to quantity of necrotic debris versus laparoscopic transmural internal drainage for walled-off necrosis in acute pancreatitis: A randomized controlled trial

Background and aimsBoth endoscopic and laparoscopic transmural internal drainage are practiced for drainage of walled-off necrosis (WON) following acute pancreatitis (AP) but the superiority of either is not established. Our aim was to compare transperitoneal laparoscopic drainage with endoscopic drainage using either lumen apposing metal stents (LAMS) or plastic stents tailored to the amount of necrotic debris in WON. MethodsIn a randomized controlled trial, adequately powered to exclude the null hypothesis, patients with symptomatic WON were randomized to either endoscopic or laparoscopic drainage. In the endoscopy group, two plastic stents were placed if the WON contained <1/3rd necrotic debris and a LAMS was placed if it was >1/3rd. Primary outcome was resolution of WON within 4 weeks without re-intervention for secondary infection. Secondary outcome was overall success (resolution of WON at 6 months) and adverse events. ResultsForty patients were randomized: 20 to each group. Baseline characteristics were comparable between the groups. Primary outcome was similar between the groups [16 (80%) in laparoscopy and 15 (75%) in endoscopy group; p = 0.89]. The overall success was similar [18 (90%) in laparoscopy vs. 17 (85%) in endoscopy; p = 0.9]. Median duration of hospital stay was shorter in endoscopy group [4 (4–8) vs. 6 days (5–9); p = 0.03]. Adverse events were comparable between the groups. ConclusionLaparoscopic drainage was not superior to endoscopic transmural drainage with placement of multiple plastic stent or LAMS depending on the amount of necrotic debris for symptomatic WON in AP. The hospital stay was shorter with the endoscopic approach.

Comparing the environmental performance of distributed versus centralized plastic recycling systems: Applying hybrid simulation modeling to life cycle assessment

The plastic waste dilemma has gained international attention because of increased public awareness and the rise of waste import bans. Sorting and recycling technologies that deal with plastic waste streams exist but face challenges in highly dense urbanized regions such as Singapore because of high space requirements. Multiple small-scale plastic sorting and recycling facilities that are distributed closer to points of waste generation offer the possibility of increasing the recovery of plastic-waste streams in urbanized settings. To holistically quantify the environmental performance of this type of system, a life cycle assessment (LCA) is conducted to compare five different scenarios of distributed and centralized sorting and recycling of plastic bottles and takeaway containers in Singapore. A hybrid simulation model is used to simulate the complex dynamics of waste-processing systems which involves waste generation, collection scheduling, sorting, recycling, and disposal of residual materials. The results of the LCA showed that the life cycle environmental impacts to climate change, water depletion, and terrestrial ecotoxicity of the distributed scenarios were higher than the centralized scenarios by 7–30% depending on the impact category. Although the distributed scenarios had lower total travel distances, their reliance on commercial vans led to their higher environmental impacts than the centralized scenarios. The findings of this study provide motivation for future research in applying hybrid simulation models in LCAs of waste-to-resource exchange networks. The data used to carry out the hybrid simulations and the LCA are provided as Supporting Information. This article met the requirements for a Gold-Silver JIE data openness badge described at http://jie.click/badges.