Microfluidic Synthesis of Multifunctional Micro-/Nanomaterials from Process Intensification: Structural Engineering to High Electrochemical Energy Storage.

Multifunctional micro-/nanomaterials featuring functional superiority and high value-added physicochemical nature have received immense attention in electrochemical energy storage. Microfluidic synthesis has become an emergent technology for massively producing multifunctional micro-/nanomaterials with tunable microstructure and morphology due to its rapid mass/heat transfer and precise fluid controllability. In this review, the latest progresses and achievements in microfluidic-synthesized multifunctional micro-/nanomaterials are summarized via reaction process intensification, multifunctional micro-/nanostructural engineering and electrochemical energy storage applications. The reaction process intensification mechanisms of various micro-/nanomaterials, including quantum dots (QDs), metal materials, conducting polymers, metallic oxides, polyanionic compounds, metal-organic frameworks (MOFs) and two-dimensional (2D) materials, are discussed. Especially, the multifunctional structural engineering principles of as-fabricated micro-/nanomaterials, such as vertically aligned structure, heterostructure, core-shell structure, and tunable microsphere, are introduced. Subsequently, the electrochemical energy storage application of as-prepared multifunctional micro-/nanomaterials is clarified in supercapacitors, lithium-ion batteries, sodium-ion batteries, all-vanadium redox flow batteries, and dielectric capacitors. Finally, the current problems and future forecasts are illustrated.

Microfluidic Printing of Vertically-Oriented Nanosheets/MOFs Hetero-Interface for Intensive Pseudocapacitive Storage.

Efficient manufacture of electroactive vertically-oriented nanosheets with enhanced electrolyte mass diffusion and strong interfacial redox dynamics is critical for realizing high energy density of miniature supercapacitor (SC), but still challenging. Herein, microfluidic droplet printing is developed to controllably construct vertically-oriented graphene/ZIF-67 hetero-microsphere (VAGS/ZIF-67), where the ZIF-67 is coordinately grown on vertically-oriented graphene framework via Co─O─C bonds. The VAGS/ZIF-67 shows ordered porous channel, high electroactivity and strong interfacial interaction, providing rapid electrolyte diffusion dynamics and high faradaic capacitance in KOH solution (1674 F g-1 , 1004 C g-1 ), which are verified by computational fluid dynamics (CFD) and density functional theory (DFT). Moreover, the VAGS/ZIF-67 based SC exhibits large energy density (100 Wh kg-1 ), excellent durability (10 000 cycles and high/low temperature), and robust power-supply applications in portable electronics.

Two-Dimensional Hybrid Nanosheet-Based Supercapacitors: From Building Block Architecture, Fiber Assembly, and Fabric Construction to Wearable Applications.

Fiber-based supercapacitors (F-SCs) have inspired widespread interest in the fields of wearable technology, energy, and carbon neutralization due to their highly deformable flexibility, fast charging/discharging capability, long-term stability, and energy conservation ability. In this review, we summarize the latest developments for fabricating fibrous electrodes of F-SCs where advanced micro two-dimensional (2D) building blocks (e.g., MXene and graphene) are chemically assembled and constructed into ordered mesofibers and multifunctional macrofabrics. Diverse fundamental principles of 2D hybrid nanosheets with respect to surface controls, pseudocapacitive modifications, and microstructural manipulations, promoting rapid electron transfer and charge conduction, are introduced. Additionally, various spinning methods for assembling and fabricating sophisticated fibers with advanced nano/microstructures, including hierarchical skeletons, anisotropic backbones, surface/entire porous frameworks, and vertical-aligned networks, for boosting ionic kinetic transport/storage are presented. Likewise, the structure-activity relationships between the porous structure and electrochemical performance are clarified. Moreover, multifunctional fabrics in terms of high flexibilities/strengths, superior electrical conductivities, and stabilized operations, which realize large energy density, deformable capability, and robust stability under harsh conditions, are emphasized. In particular, the potential power-supply applications, including flexible electronic devices, self-powered functions, and energy-sensor systems, are highlighted. Finally, a short conclusion and outlook, along with the current challenges and future opportunities of next-generation F-SCs, are proposed.

Interfacial Polymetallic Oxides and Hierarchical Porous Core-Shell Fibres for High Energy-Density Electrochemical Supercapacitors.

Realizing high energy-density and actual applications of fibre-based electrochemical supercapacitors (FESCs) are pivotal but challenging, as the ability to construct advanced fibres for accelerating charges kinetic diffusion and Faradaic storage remain key bottlenecks. Here, we demonstrate high-performance FESCs based on hetero-structured polymetallic oxides/porous graphene core-sheath fibres, where the large pseudo-active polymetallic oxide (PMO) sheath is uniformly loaded on a hierarchical porous graphene fibre (PGF) core. Due to the abundant micro-/mesoporous pathways, large accessible surface, excellent redox activity and good interface electron conduction, the PMO-PGF possesses high areal capacitance (2959.78 mF cm-2 ) and manageable Faradaic reversibility in a 6 M KOH electrolyte. Furthermore, the PMO-PGF-based solid-state FESCs present high energy-density (187.22 µ Wh cm-2 ), long-life cycles (95.8 % capacitive retention after 20 000 cycles), diverse-powered capabilities and actual energy-supply applications.

Armored colloidal photonic crystals for solar evaporation.

Colloidal photonic crystals (CPCs) with a highly ordered crystal structure have attracted great attention in displays, colorimetric sensors and solar energy utilization fields. However, the easily cracking microstructure, inferior assembly efficiency and low refractive index contrast result in poor structural colors. Herein, we develop core-shell poly(styrene-acrylic)@polypyrrole (P(St-AA)@PPy) colloidal nanoparticles by the in situ chemical coupling reaction via droplet microfluidic technology. By membrane separation-assisted assembly (MSAA) and electrostatic spraying strategies, the P(St-AA)@PPy colloidal nanoparticles are assembled into the CPC film, which presents high assembly efficiency and saturated angle-independent structural colors, due to the light-absorbing PPy shell and hydrogen-bond interaction between nanoparticles. Benefitting from these outstanding performances, the P(St-AA)@PPy film shows excellent photothermal properties, which can realize a solar vaporization rate of 1.5825 kg m-2 h-1, corresponding to a light-to-vapor efficiency of 94.20%, under 1.0 sun solar irradiance conditions. Our findings open a path for the design of functional CPCs and new-generation photothermal applications.

Covalently Aligned Molybdenum Disulfide-Carbon Nanotubes Heteroarchitecture for High-Performance Electrochemical Capacitors.

Advanced two-dimensional nanosheets that promote the dynamic transportation and storage capacity of ions are significant for high-performance electrochemical capacitors (ECs). However, such materials often possess a low energy density. We have developed an ordered heteroarchitecture of molybdenum disulfide-carbon nanotubes (MoS2 -CNTs) in which CNTs are vertically grafted within a MoS2 framework by C-Mo covalent bonds. Benefiting from this in situ vertical bridge, high-speed interlaminar conductivity, unimpeded ion-diffusion channels and sufficient pseudocapacitive reactivity, the MoS2 -CNTs presents ultralarge capacitance (5485 F g-1 ) and good structural stability in potassium hydroxide electrolyte. Moreover, the all-unified solid-state flexible ECs obtained through direct-write printing construction deliver high energy density (226 mWh g-1 ), good capacitance (723 F g-1 ) and stable high/low-temperature operating ability, which can power a wearable health-monitoring device.

A Covalent Black Phosphorus/Metal-Organic Framework Hetero-nanostructure for High-Performance Flexible Supercapacitors.

We develop hetero-nanostructured black phosphorus/metal-organic framework hybrids formed by P-O-Co covalent bonding based on a designed droplet microfluidic strategy consisting of confined and ultrafast microdroplet reactions. The resulting hybrid exhibits large capacitance (1347 F g-1 ) in KOH electrolytes due to its large specific-surface-area (632.47 m2 g-1 ), well-developed micro-porosity (0.38 cm3 g-1 ), and engineered electroactivity. Furthermore, the proposed 3D printing method allows to construct all-integrated solid-state supercapacitor, which maintains interconnected porous network, good interfacial adhesion, and robust flexibility for short-path diffusion and excessive accommodation of ions. Consequently, the fabricated flexible supercapacitor delivers ultrahigh volumetric energy density of 109.8 mWh cm-3 , large capacitance of 506 F cm-3 , and good long-term stability of 12000 cycles.

Anisotropic Boron-Carbon Hetero-Nanosheets for Ultrahigh Energy Density Supercapacitors.

A 2D boron nanosheet that exhibits high theoretical capacitance, around four times that of graphene, is a significant supercapacitor electrode. However, its bulk structure with low interlaminar conduction and porosity restricts the charge transfer, ion diffusion, and energy density. Herein, we develop a new 2D hetero-nanosheet made of anisotropic boron-carbon nanosheets (ABCNs) by B-C chemical bonds via gas-phase exfoliation and condensation bottom-up strategy. The ABCNs are constructed into high flexible supercapacitor electrode by microfluidic electrospinning. The ABCN electrode greatly promotes smooth migration and excessive storage of electrolyte ions due to large interlayer conductivity, ionic pathways, and accessible surfaces. The flexible supercapacitor delivers ultrahigh volumetric energy density of 167.05 mWh cm-3 and capacitance of 534.5 F cm-3 . A wearable energy-sensor system is designed to stably monitor physiological signals.

Robust hydrophobic veova10-based colloidal photonic crystals towards fluorescence enhancement of quantum dots.

Hydrophobic photonic crystals (PCs) has been increasingly appreciated as a promising functional material due to their distinct surface characteristic of structural color and hydrophobicity. However, it remains a challenge to fabricate hydrophobic PCs via a one-step process. Inspired by the development of high-performance waterborne coatings, we propose an easy-to-perform and high-efficiency strategy to construct hydrophobic building blocks (diameter of 221, 247, 276 and 305 nm), where the umbelli-form hydrophobic long chain (veova10 Cn > 9) was loaded onto polystyrene (PS) colloidal particles in situ. Taking advantage of the hydrophobic driving force between the colloidal particles, large-scale colloidal photonic crystals (CPCs) film with crack-free morphology was obtained efficiently. The derived CPCs exhibit robust mechanical stability, prominent hydrophobicity and excellent optical properties. In addition, the colloidal latex holds great potential toward PCs coatings on a variety of substrates (glass, plastic and steel) with excellent adhesiveness. Furthermore, we contrive to construct angle-independent structural color films and supraballs, and explore their application in quantum dots (QDs) fluorescence enhancement, which achieved an enhancement effect by more than eight times. From the standpoint of practical applications, we achieved the flexible high-brightness wearable light-emitting diode (LED) displays. This work will lay a foundation for the development of high-efficiency PCs building blocks, and indicate the direction for the meaningful application of CPCs.

Microfluidic-Architected Nanoarrays/Porous Core-Shell Fibers toward Robust Micro-Energy-Storage.

Methods enabling the controllable fabrication of orderly structural and active nanomaterials, along with high-speed ionic pathways for charge migration and storage are highly fundamental in fiber-shaped micro-supercapacitors (MSCs). However, due to fiber-electrodes with compact internal microstructure and less porosity, MSCs usually display a low energy density. Here, an innovative microfluidic strategy is proposed to design ordered porous and anisotropic core-shell fibers based on nickel oxide arrays/graphene nanomaterials. Owing to the homogeneous microchannels reaction, the graphene core maintains a uniformly anisotropic porous structure, and the nickel oxide shell keeps steadily vertically aligned nanosheets. The MSC presents an ultrahigh energy density (120.3 µWh cm-2) and large specific capacitance (605.9 mF cm-2). This higher performance originates from the microfluidic-architected core-shell fiber with abundant ionic channels (plentiful micro-/mesopores), large specific-surface-area (425.6 m2 g-1), higher electrical conductivity (176.6 S cm-1), and sufficient redox activity, facilitating ions with quicker diffusion and greater accumulation. Considering those outstanding properties, a wearable self-powered system, converting and storing solar energy into electric energy, is designed to light up displays. This microfluidic strategy offers an effective way to design new structural materials, which will advance the development of next-generation wearable/smart industries.

Evaluation of Endovascular Therapy Combined with Bowel Resection Treatment on Patients with Acute Mesenteric Venous Thrombosis.

BACKGROUND: This retrospective study aims to investigate the effects of the endovascular and surgical strategy for treating patients with acute mesenteric venous thrombosis (AMVT). METHODS: We retrospectively studied 68 patients with AMVT who underwent treatment in Jinling Hospital during the period from January 2009 to December 2014. The mean age was 45 ± 12 years (range 20-72 years). All patients were treated by using the combined treatment that included endovascular treatment, damage control surgery, surgical intensive care, and intestinal rehabilitation treatment. Clinical outcomes and complications were compared during the follow-up period. RESULTS: All the 68 cases received anticoagulant treatment. However, only 24 received the endovascular intervention, 19 received surgical resection, and 25 patients received endovascular treatment combined with bowel resection. The overall mortality rate was 2.94% (2 cases). Bowel resection range significantly decreased (92 ± 14 cm vs. 162 ± 27 cm, t = -2.377, P = 0.022) in the combination therapy group, when compared with the surgery group. During the 1-year follow-up period, 4 cases suffered from short bowel syndrome. CONCLUSIONS: Our study indicates that AMVT can be successfully treated with the early improvement of intestinal blood circulation. Further, our applied combined approach showed a favorable outcome in mesenteric thrombosis patients and reduced the mortality rate by improving the prognosis significantly.

Microfluidics-Assisted Assembly of Injectable Photonic Hydrogels toward Reflective Cooling.

Development of fast curing and easy modeling of colloidal photonic crystals is highly desirable for various applications. Here, a novel type of injectable photonic hydrogel (IPH) is proposed to achieve self-healable structural color by integrating microfluidics-derived photonic supraballs with supramolecular hydrogels. The supramolecular hydrogel is engineered via incorporating ß-cyclodextrin/poly(2-hydroxypropyl acrylate-co-N-vinylimidazole) (CD/poly(HPA-co-VI)) with methacrylated gelatin (GelMA), and serves as a scaffold for colloidal crystal arrays. The photonic supraballs derived from the microfluidics techniques, exhibit excellent compatibility with the hydrogel scaffolds, leading to enhanced assembly efficiency. By virtue of hydrogen bonds and host-guest interactions, a series of self-healable photonic hydrogels (linear, planar, and spiral assemblies) can be facilely assembled. It is demonstrated that the spherical symmetry of the photonic supraballs endows them with identical optical responses independent of viewing angles. In addition, by taking the advantage of angle independent spectrum characteristics, the IPH presents beneficial effects in reflective cooling, which can achieve up to 17.4 °C in passive solar reflective cooling. The strategy represents an easy-to-perform platform for the construction of IPH, providing novel insights into macroscopic self-assembly toward thermal management applications.

Hydrophobic Poly(tert-butyl acrylate) Photonic Crystals towards Robust Energy-Saving Performance.

Photonic crystals (PCs) have been widely applied in optical, energy, and biological fields owing to their periodic crystal structure. However, the major challenges are easy cracking and poor structural color, seriously hindering their practical applications. Now, hydrophobic poly(tert-butyl acrylate) (P(t-BA)) PCs have been developed with relatively lower glass transition temperature (Tg ), large crack-free area, excellent hydrophobic properties, and brilliant structure color. This method based on hydrophobic groups (tertiary butyl groups) provides a reference for designing new kinds of PCs via the monomers with relatively lower Tg . Moreover, the P(t-BA) PCs film were applied as the photoluminescence (PL) enhanced film to enhance the PL intensity of CdSe@ZnS QDs by 10-fold in a liquid-crystal display (LCD) device. The new-type hydrophobic force assembled PCs may open an innovative avenue toward new-generation energy-saving devices.

Outcomes and clinical characteristics of transmural intestinal necrosis in acute mesenteric ischemia.

Background: Acute mesenteric ischemia (AMI) is a rare life-threatening condition, especially for the patients with transmural intestinal necrosis (TIN). However, the optimal time for surgical intervention is controversial. As a series study, this study aimed to identify the outcomes and clinical characteristic of patients with TIN. Methods: Clinical data of 158 patients with AMI from January 2010 to December 2017 were retrospectively analyzed in a national gastrointestinal referral center in China to confirm the outcomes and identify predictors for TIN. Results: According to the results of pathological assessment and follow-up, 62 patients were TIN and 96 were non-TIN. Patients with TIN have a higher mortality and incidence of severe complications. The significant independent predictors for TIN were arterial lactate level (OR: 4.76 [2.29 ∼ 9.89]), free intraperitoneal fluid (OR: 9.49 [2.56 ∼ 35.24]) and pneumatosis intestinalis (OR: 7.08 [1.68 ∼ 29.82]) in computed tomography (CT) scan imaging. The overall area under the receiver operating characteristics (ROC) curve of the model was 0.934 (95% confidence interval: 0.893 ∼ 0.974). Using ROC curve, the cutoff value of arterial lactate level predicting the onset of TIN was 2.65 mmol/L. Conclusions: Patients concomitant with TIN manifest a higher risk of poor prognosis. The three predictors for TIN were arterial lactate level >2.65 mmol/L, free intraperitoneal fluid and pneumatosis intestinalis. Close monitoring these predictors would help identify AMI patients developed TIN and in urgent need for bowel resection.

High-Performance Hierarchical Black-Phosphorous-Based Soft Electrochemical Actuators in Bioinspired Applications.

Bioinspired methods allowing artificial actuators to perform controllably are potentially important for various principles and may offer fundamental insight into chemistry and engineering. To date, the main challenges persist regarding the achievement of large deformation in fast response-time and potential-engineering applications in which electrode materials and structures limit ion diffusion and accumulation processes. Herein, a novel electrochemical actuator is developed that presents both higher electromechanical performances and biomimetic applications based on hierachically structured covalently bridged black phosphorous/carbon nanotubes. The new actuator demonstrates astonishing actuation properties, including low power consumption/strain (0.04 W cm-2 %-1 ), a large peak-to-peak strain (1.67%), a controlled frequency response (0.1-20 Hz), faster strain and stress rates (11.57% s-1 ; 28.48 MPa s-1 ), high power (29.11 kW m-3 ), and energy (8.48 kJ m-3 ) densities, and excellent cycling stability (500 000 cycles). More importantly, bioinspired applications such as artificial-claw, wings-vibrating, bionic-flower, and hand actuators have been realized. The key to high performances stems from hierachically structured materials with an ordered lamellar structure, large redox activity, and electrochemical capacitance (321.4 F g-1 ) for ions with smooth diffusion and flooding accommodation, which will guide substantial progress of next-generation electrochemical actuators.

Endovascular stent placement for isolated superior mesenteric artery dissection with intestinal ischaemia.

BACKGROUND: Isolated superior mesenteric artery dissection (ISMAD) is rare, especially when associated with intestinal ischaemia. We report our clinical experience managing this condition. PATIENTS AND METHODS: Medical records from 22 patients with ISMAD and intestinal ischaemia were retrospectively analysed. Conservative treatment was given to all patients as first line therapy. Subsequently, 15 patients received endovascular stent placement and three patients received endovascular stent placement plus intestinal resection and anastomosis. RESULTS: After conservative treatment, the symptoms of three patients were remarkably relieved; however, a repeat contrast CT showed that stenosis was aggravated. Hence, endovascular stent placement was performed in all 15 patients. Enteral nutrition was successfully restored in 12 patients. Three patients showed signs of chronic intestinal ischaemia, including peritonitis and ileus. These patients underwent intestinal resection and anastomosis. Enteral nutrition was restored at postoperative week two. No signs of intestinal ischaemia recurred during two-years of follow-up. CONCLUSIONS: We recommend endovascular stent placement as a feasible, effective, and minimally invasive procedure in patients with ISMAD and symptoms of intestinal ischaemia.

Facile synthesis of carbon nanobranches towards cobalt ion sensing and high-performance micro-supercapacitors.

We present a facile strategy for fabricating a new type of one-dimensional (1D) carbon nanomaterial named carbon nanobranches (CNBs) covered with botryoidal carbon dots (CDs) by direct pyrolysis of a green precursor (starch). The resultant CNBs display both photoluminescence and electrical conductivity and can be assembled into chemical sensors and energy-storage devices. In terms of their bright photoluminescence, CNBs with a fabulous crystalline structure are utilized as fluorescent probes to sensitively and selectively detect Co2+ with a very low detection limit of 2.85 nM and a wide linear concentration range from 10 nM to 1 mM. Moreover, an efficient micro-supercapacitor (micro-SC) is constructed based on conductive CNB fibers produced via a customized microfluidic spinning technique. The micro-SCs exhibit a large specific capacitance of 201.4 mF cm-2, an energy density of 4.5 µW h cm-2 and high cycling stability, and can successfully power 19 light-emitting diodes (LEDs). The main purpose of this paper is to offer a perspective into simplifying the connecting of research and industry by starting from green carbon-based materials.

DNase-1 Treatment Exerts Protective Effects in a Rat Model of Intestinal Ischemia-Reperfusion Injury.

A growing number of studies have recently revealed a potential role for neutrophil extracellular traps (NETs) in the development of inflammation, coagulation and cell death. Deleterious consequences of NETs have been identified in ischemia-reperfusion (I/R)-induced organ damage, thrombosis and sepsis. And exogenous DNase-I has been suggested as a therapeutic strategy to attenuate ischemia-reperfusion (I/R) injuries in the kidney, brain and myocardium. Herein, we designed a study to investigate whether NETs contribute to the pathogenesis of intestinal I/R injury and evaluated the therapeutic value of DNase-1 in a rat model of intestinal I/R injury. In this rat model of intestinal I/R injury, we found that extracellular DNA was readily detectable in rat serum after 1 h of ischemia and 2 h of reperfusion. Treatment with DNase-1 significantly reduced the inflammatory response, restored intestinal barrier integrity and increased the expression of tight junction proteins. Our results indicate the existence of NETs in I/R-challenged intestinal tissues and firstly provide more evidence that DNase-1 may be an effective treatment for attenuating intestinal I/R injury.

Microfluidic-spinning construction of black-phosphorus-hybrid microfibres for non-woven fabrics toward a high energy density flexible supercapacitor.

Flexible supercapacitors have recently attracted intense interest. However, achieving high energy density via practical materials and synthetic techniques is a major challenge. Here, we develop a hetero-structured material made of black phosphorous that is chemically bridged with carbon nanotubes. Using a microfluidic-spinning technique, the hybrid black phosphorous-carbon nanotubes are further assembled into non-woven fibre fabrics that deliver high performance as supercapacitor electrodes. The flexible supercapacitor exhibits high energy density (96.5 mW h cm-3), large volumetric capacitance (308.7 F cm-3), long cycle stability and durability upon deformation. The key to performance lies in the open two-dimensional structure of the black phosphorous/carbon nanotubes, plentiful channels (pores <1 nm), enhanced conduction, and mechanical stability as well as fast ion transport and ion flooding. Benefiting from this design, high-energy flexible supercapacitors can power various electronics (e.g., light emitting diodes, smart watches and displays). Such designs may guide the development of next-generation wearable electronics.

Open Abdomen Improves Survival in Patients With Peritonitis Secondary to Acute Superior Mesenteric Artery Occlusion.

BACKGROUND: Damage control surgery and open abdomen (OA) have been extensively used in the severe traumatic patients. However, there was little information when extended to a nontrauma setting. The purpose of this study was to evaluate whether the liberal use of OA as a damage control surgery adjunct improved the clinical outcome in acute superior mesenteric artery occlusion patients. STUDY DESIGN: A single-center, retrospective cohort review was performed in a national tertiary surgical referral center. RESULTS: Forty-four patients received OA (OA group) and 65 patients had a primary fascial closure (non-OA group) after diagnosed as peritonitis secondary to acute superior mesenteric artery occlusion from January, 2005 to June, 2016. Revascularization was achieved through endovascular aspiration embolectomy, open embolectomy, or percutaneous stent. No difference of bowel resection length was found between groups in the first emergency surgery. However, more non-OA patients (35.4%) required a second-look enterectomy to remove the residual bowel ischemia than OA patients (13.6%, P<0.05). OA was closed within a median of 7 days (4 to 15 d). There was a mean of 134 cm residual alive bowel in OA, whereas 96 cm in non-OA. More non-OA patients suffered from intra-abdominal sepsis (23.1% vs. 6.8%, P<0.01), intra-abdominal hypertension (31% vs. 0, P<0.01), and acute renal failure (53.8% vs. 31.8%, P<0.05) than OA group after surgery. Short-bowel syndrome occurred infrequently in OA than non-OA patients (9.1% vs. 36.9%, P<0.01). OA significantly decreased the 30-day (27.3% vs. 52.3%, P<0.01) and 1-year mortality rate (31.8 % vs. 61.5%, P<0.01) compared with non-OA group. CONCLUSIONS: Liberal use of OA, as a damage control adjunct avoided the development of intra-abdominal hypertension, reduced sepsis-related complication, and improved the clinical outcomes in peritonitis secondary to acute SMA occlusion.