Contribution to Improvement of Fatigue Properties of Zr-4 Alloy: Gradient Nanostructured Surface Layer versus Compressive Residual Stress

The gradient nanostructured (GNS) layer forms beneath the surface of Zr-4 samples by the surface mechanical grinding treatment (SMGT) process, which increases the fatigue strength apparently due to the synergistic effect of the gradient nanostructured layer and compressive residual stress. The SMGTed Zr-4 samples are subjected to annealing to remove residual stress (A-SMGT) and the individual effect of the GNS layer and compressive residual stress can be clarified. The results show that the gradient nanostructure in the surface is stable after annealing at 400 °C for 2 h but residual stress is apparently removed. Both SMGTed and A-SMGTed Zr-4 samples exhibit higher fatigue strength than that of coarse-grained (CG) Zr-4 alloy. The fatigue fracture of Zr-4 alloy indicates that the hard GNS surface layer hinders fatigue cracks from approaching the surface and leads to a lower fatigue striation space than that of CG Zr-4 samples. The offset fatigue strength of 106 cycles is taken for SMRT-ed, A-SMRT-ed, and CG Zr-4 samples and the results indicate clearly that the GNS surface layer is a key factor for the improvement of fatigue strength of the Zr-4 alloy with surface mechanical grinding treatment.

Study of clinical outcome of patients undergoing intestinal anastomoses with single layer extramucosal technique and double layer anastomoses

Background: Intestinal anastomosis is one of the common surgeries for cases like bowel obstruction, incarcerated hernias, benign and malignant tumours of small and large bowel. The ideal intestinal anastomosis does not leak and allow normal function of the gastrointestinal tract. This study compared single layer versus double layer intestinal anastomosis in terms of duration, postoperative complications like anastomotic leak.Methods: A total of 100 patients admitted in Hamidia hospital, based on history and clinical examinations and radiological examinations, placed in two groups, group A (single layer anastomosis) and group B (double layer anastomosis) and were operated by a qualified surgical specialist. Data analysis of anastomotic time, anastomotic leak was done and statistical tests of significance were applied. A p value less than 0.05 is considered as significant.Results: In group A (single layer) the time required to perform in 30 (60%) patients is between 16-20 minutes. In double layer, maximum were done in between 26 to 30 minutes, 32 (64%). In our study of 100 patients, there were 6 anastomotic leaks, of which four of them were in group A (single layer) and 2 of them in group B (double layer).Conclusions: In our study, the duration required to perform a single layer intestinal anastomosis is significantly lesser when compared to double layer. There is no significant difference in anastomotic leak between two groups. Less time with no difference in complications, a move towards single layer anastomosis should be preferred.

Comparison of multiple-layer versus multiple-cavity microperforated panels for sound absorption at low frequency

Microperforated panels (MPPs) are recognized as suitable absorbers for noise control applications demanding special clean and health requirements.While it is relatively easy to design single-layer MPPs for sound absorption in one-to-two octave bands at medium-high frequencies, the performance for low frequencies (below 600 Hz) leads to a rather narrow-band absorption, similar to that of a Helmholtz resonator. However, multiple-layer MPPs can be designed as sound absorbers that yield low-frequency absorption in a wide frequency band. Recently, multiple-cavity perforated panels have been proposed to improve the performance of MPPs in the low-frequency range. In this article, the capability of multiple-layer and multiple-cavity MPPs to provide sound absorption at low frequencies is analyzed.

A COMPARATIVE STUDY BETWEEN SINGLE LAYER VERSUS DOUBLE LAYER INTESTINAL ANASTOMOSIS

A comparative study between Single Layer versus Double Layer Intestinal Anastomosis,was undertaken at Department of Surgery,Bankura Sammilani Medical College & Hospital,Bankura from April 2019 – September 2020,which included 74 patients, comprising 2 groups: Group A-Single layer and Group B- Double layer with equal number of patients randomly allotted in each group. More number of patients had anastomotic leak in Group B than Group A, though not statistically significant. Difference of Mean Duration of Anastomosis with both groups is statistically significant.Mean Duration of Hospital Stay with both groups is statistically insignificant. Although more number of patients had anastomotic leaks in Group B than Group A,it was statistically insignificant.

Ileo-colic intra-corporeal anastomosis during robotic right colectomy: a systematic literature review and meta-analysis of different techniques

Purpose Robotic assistance could increase the rate of ileo-colic intra-corporeal anastomosis (ICA) during robotic right colectomy (RRC). However, although robotic ICA can be accomplished with several different technical variants, it is not clear whether some of these technical details should be preferred. An evaluation of the possible advantage of one respect to another would be useful. Methods We conducted a systematic review of literature on technical details of robotic ileo-colic ICA, from which we performed a meta-analysis of clinical outcomes. The extracted data allowed a comparative analysis regarding the outcome of overall complication (OC), bleeding rate (BR) and leakage rate (LR), between (1) mechanical anastomosis with robotic stapler, versus laparoscopic stapler, versus totally hand-sewn anastomosis and (2) closure of enterocolotomy with manual double layer, versus single layer, versus stapled. Results A total of 30 studies including 2066 patients were selected. Globally, the side-to-side, isoperistaltic anastomosis, realized with laparoscopic staplers, and double-layer closure for enterocolotomy, is the most common technique used. According to the meta-analysis, the use of robotic stapler was significantly associated with a reduction of the BR with respect to mechanical anastomosis with laparoscopic stapler or totally hand-sewn anastomosis. None of the other technical aspects significantly influenced the outcomes. Conclusions ICA fashioning during RRC can be accomplished with several technical variants without evidence of a clear superiority of anyone of these techniques. Although the use of robotic staplers could be associated with some benefits, further studies are necessary to draw conclusions.