Numerical analysis of the repair performance of Notched Cracked Composite Structure repaired by composite patch

In this article we analytically examined by three-dimensional finite element method the repair performance of a plate made of different composite materials (Boron/epoxy, Graphite/epoxy and Glass/epoxy), notched on V-shape by a composite patch of different shapes (Total, Normal and V-shaped). The damaged area ratio of the adhesive layer, the stress distribution and the stress intensity factor at the crack tip were calculated in order to evaluate the performance of the composite materials in repairing this damage and to determine which shapes and types are most efficient in repair. At the end of the study, the results obtained showed that boron/epoxy is more resistant to fracture than other materials and that the total shape of the composite patch is the good shape for our repair because it gives good performance and is more efficient compared to other shapes (normal, V-shaped).

Numerical analysis of the repair performance of Notched Cracked Composite Structure repaired by composite patch

In this article we analytically examined by three-dimensional finite element method the repair performance of a plate made of different composite materials (Boron/epoxy, Graphite/epoxy and Glass/epoxy), notched on V-shape by a composite patch of different shapes (Total, Normal and V-shaped). The damaged area ratio of the adhesive layer, the stress distribution and the stress intensity factor at the crack tip were calculated in order to evaluate the performance of the composite materials in repairing this damage and to determine which shapes and types are most efficient in repair. At the end of the study, the results obtained showed that boron/epoxy is more resistant to fracture than other materials and that the total shape of the composite patch is the good shape for our repair because it gives good performance and is more efficient compared to other shapes (normal, V-shaped).

6-Methyl-7,7,9-tripropargyl-7H-1,2,4-triazolo[4,3-b][1,2,4]triazepin-8(9H)-one

The title compound, C15H13N5O, features a triazolyl ring fused with a seven-membered triazepinyl ring; the latter ring adopts a boat conformation (with the propargyl-bearing C atom as the prow and the fused-ring C/N atoms as the stern)

7,9-Diallyl-6-methyl-7H-1,2,4-triazolo[4,3-b][1,2,4]triazepin-8(9H)-one

The title compound, C12H15N5O, features a triazolyl ring fused with a seven-membered triazepinyl ring; the latter ring adopts a boat conformation with the allyl-bearing C atom as the prow and the C and N fused-ring atoms as the stern

1-Benzyl-3-[(dimethyl­amino)methyl­ene]-4-phenyl-1H-1,4-benzodiazepin-2(3H)-one

The title compound, C25H23N3O, features a benzene ring fused with a seven-membered 1,4-diazepine ring; the latter ring adopts a boat conformation with the (dimethyl­amino)methyl-bearing C atom as the prow and the fused-ring C atoms as the stern. There are two independent mol­ecules in the asymmetric unit with similar conformations

Properties and performance of mesoporous activated carbons from scrap tyres, bituminous wastes and coal

Tyre wastes and their blends with coal and a bituminous waste material obtained from the benzol distillation column of a by-product section of a coking plant were employed as a precursor for the production of activated carbons (ACs). Pyrolysis up to 850 °C followed by physical activation with CO2 produced mesoporous carbons with different pore size distributions and surface areas. The surface chemistry of the samples was studied by measuring the point of zero charge (pHpzc) and by temperature programmed desorption (TPD). The activated carbons obtained contained higher amounts of basic functional groups. Their textural and surface chemistry characteristics make them highly suitable for adsorbing anionic dyes of large molecular size, such as Congo red. The adsorption kinetics was found to conform closely to the pseudo-second-order kinetic model. To determine the adsorption mechanism, the kinetic data were also analyzed using the Weber and Morris intraparticle diffusion model and the Boyd model to distinguish between the pore and film diffusion steps. The equilibrium isotherms were of the Langmuir isotherm type. The efficiency of the low-cost ACs prepared for the removal of Congo red dye was similar to that reported in the literature for coal-based ACs and greater than that of other low-cost ACs

Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy

Background A reliable system for grading operative difficulty of laparoscopic cholecystectomy would standardise description of findings and reporting of outcomes. The aim of this study was to validate a difficulty grading system (Nassar scale), testing its applicability and consistency in two large prospective datasets. Methods Patient and disease-related variables and 30-day outcomes were identified in two prospective cholecystectomy databases: the multi-centre prospective cohort of 8820 patients from the recent CholeS Study and the single-surgeon series containing 4089 patients. Operative data and patient outcomes were correlated with Nassar operative difficultly scale, using Kendall’s tau for dichotomous variables, or Jonckheere–Terpstra tests for continuous variables. A ROC curve analysis was performed, to quantify the predictive accuracy of the scale for each outcome, with continuous outcomes dichotomised, prior to analysis. Results A higher operative difficulty grade was consistently associated with worse outcomes for the patients in both the reference and CholeS cohorts. The median length of stay increased from 0 to 4 days, and the 30-day complication rate from 7.6 to 24.4% as the difficulty grade increased from 1 to 4/5 (both p < 0.001). In the CholeS cohort, a higher difficulty grade was found to be most strongly associated with conversion to open and 30-day mortality (AUROC = 0.903, 0.822, respectively). On multivariable analysis, the Nassar operative difficultly scale was found to be a significant independent predictor of operative duration, conversion to open surgery, 30-day complications and 30-day reintervention (all p < 0.001). Conclusion We have shown that an operative difficulty scale can standardise the description of operative findings by multiple grades of surgeons to facilitate audit, training assessment and research. It provides a tool for reporting operative findings, disease severity and technical difficulty and can be utilised in future research to reliably compare outcomes according to case mix and intra-operative difficulty