Application of split pancreatic duct stent in laparoscopic pancreaticoduodenectomy.

Laparoscopic pancreaticoduodenectomy (LPD) is a classic surgical method for diseases, such as tumors at the lower end of the common bile duct, pancreatic head, and benign and malignant tumors of the duodenum. Postoperative pancreatic fistula (POPF) is one of the most serious complications of LPD. To reduce the incidence of grade B or C POPF and other complications after LPD, we applied a split pancreatic duct stent combined with the characteristics of internal and external stent drainage. Between September 2020 and September 2022,12 patients underwent placement of the Split pancreatic duct stent during LPD. Data on basic characteristics of patients, surgical related indicators and postoperative POPF incidence were collected and analyzed. The results showed that the average operation time was 294.2 ± 36 minutes, average time for pancreaticojejunostomy was 35.9 ± 4.1 minutes, and average estimated blood loss was 204.2 ± 58.2 mL. Biochemical leakage occurred in 2 patients (16.7%), whereas no grade B or C POPF, 1 case (8.3%) had postoperative bleeding, and no death occurred within 30 days after the operation. Preliminary experience shows that the split pancreatic duct stent can effectively reduce the incidence of complications after LPD, especially grade B or C POPF.

Controlling Diels-Alder reactions in catalytic pyrolysis of sawdust and polypropylene by coupling CO2 atmosphere and Fe-modified zeolite for enhanced light aromatics production.

Producing value-added light aromatics (BTEX) from solid waste streams holds excellent promise for resource recovery. Here we present a thermochemical conversion approach that enhanced BTEX production by coupling CO2 atmosphere and Fe-modified HZSM-5 zeolite to facilitate the Diels-Alder reactions in catalytic pyrolysis of sawdust and polypropylene. The Diels-Alder reactions between sawdust-derived furans and polypropylene-derived olefins could be controlled by tuning CO2 concentration and Fe loading amount. Sufficient CO2 (≥50%) with moderate Fe loading (10 wt%) were observed to produce more BTEX and fewer heavy fractions (C9+aromatics). To deepen the mechanistic understanding, quantification of polycyclic aromatic hydrocarbons (PAHs) and catalyst coke was further conducted. The co-use of CO2 atmosphere and Fe modification suppressed the appearance of low-, medium-, and high-membered ring PAHs by over 40%, decreased pyrolysis oil toxicity from 42.1 to 12.8 µg/goil TEQ, and transformed coke from "hard" to "soft". Based on the characterization of CO2 adsorption behavior, it was deduced that the introduced CO2 was activated by loaded Fe and reacted in situ with H2 generated during aromatization to expedite H-transfer. Meanwhile, BTEX recondensation was prevented through the Boudouard reactions of CO2 and water-gas reactions between the resulting water and carbon deposits. These synergistically enhanced the production of BTEX and suppressed the formation of heavy species, including PAHs and catalyst coke.

Entropy, Graph Homomorphisms, and Dissociation Sets.

Given two graphs G and H, the mapping of f:V(G)→V(H) is called a graph homomorphism from G to H if it maps the adjacent vertices of G to the adjacent vertices of H. For the graph G, a subset of vertices is called a dissociation set of G if it induces a subgraph of G containing no paths of order three, i.e., a subgraph of a maximum degree, which is at most one. Graph homomorphisms and dissociation sets are two generalizations of the concept of independent sets. In this paper, by utilizing an entropy approach, we provide upper bounds on the number of graph homomorphisms from the bipartite graph G to the graph H and the number of dissociation sets in a bipartite graph G.