In this study, the Dufour and Soret effects on natural double-diffusion convection in a horizontal porous layer was studied numerically using FORTRAN 90 programming and analytically near various convection onset thresholds. The porous layer was subject to a uniform heat and mass fluxes on the horizontal walls while the vertical walls were impermeable and adiabatic. The Darcy model along with the Boussinesq approximation was assumed in the problem formulation. The governing parameters of the problem are the thermal Rayleigh number, R T , the buoyancy ratio, N, the Lewis number, Le, the aspect ratio of the cavity, A, and the Dufour, D u , andSoret, S r , numbers. For a shallow enclosure, the analytical solution was derived assuming zero convection wave number, which is valid near and above criticality. The onset of subcritical, supercritical and oscillatory convection was investigated. Two linear and nonlinear codimension-2 points were found to exist. Whether the system was subject to constant fluxes and heat and solute, regardless of the aspect ratio of the layer, the subcritical convection behavior remained the same with similarity in the thresholds expressions for subcritical bifurcation. K E Y W O R D S double diffusion, Lapwood convection, linear and nonlinear codimension-2 points, Soret and Dufour effects Heat Transfer-Asian Res. 2019;48:763-792.wileyonlinelibrary.com/journal/htj

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Introduction: Evaluate the role of neoadjuvant chemoradiotherapy (CRT) followed by an additional cycle of chemotherapy and total mesorectal excision (TME) in patients with locally advanced rectal cancer on the rate of pathologic complete response ( pCR) and tumor downstaging, their impact on survival and evaluation of treatment related toxicity and surgical complications. Methods: This prospective phase II trial included 73 patients with histopathologically proven non metastatic rectal adenocarcinoma referred from or admitted at Surgical Oncology Department, Radiotherapy Department, South Egypt Cancer Institute, and Clinical Oncology Department, Assiut University, Egypt, from March 2012 to September 2013. Radiotherapy (1.8 Gy, 5 days a week over 5 weeks, total dose 50.4 Gy, 3 D conformational technique) was given in combination with intravenous oxaliplatin 50 mg/m2 once weekly for 5 weeks and oral capecitabine 825 mg/m2 twice daily on each day of radiation. After completion of CRT, patients received an additional cycle of chemotherapy consisted of oxaliplatin (130 mg/m2 on day 1) and capecitabine (825 mg/m2, twice per day from day 1 to day 14). Surgery was performed 6-8 weeks after completion of chemoradiotherapy. Results: Seventy patients (95.9%) underwent surgery. Postoperative pathologic assessment showed an overall downstaging rate of 78.1%, while 16 patients (21.9%) had stationary disease. Complete pathologic response was achieved in 11 patients (15.1%). No tumor progression has been observed. After median follow up period of 26 months (7-30 months), the 2-year overall survival (OS) was 88%, recurrence free survival was 88.7% and distant metastasis free survival was 93.9%. Lower pathologic tumor stage was significantly associated with better OS (P = .002) and recurrence-free survival (P = .001), while pathologic nodal stage and TRG had no significant difference in overall survival, recurrence free survival or distant metastasis free survival. Forty-one patients (56.2%) experienced grade 1-2 toxicity and 5 patients (6.8%) experienced grade 3 toxicity. Conclusion: Neoadjuvant CRT and one cycle of chemotherapy followed by TME is effective with pCR of 15.1% and overall downstaging rate of 78.1%. In addition to favorable toxicity profile (lower grade 3 and 4 toxic effects as 3 patients developed grade 3 diarrhea and 2 patients developed grade 3 hematological toxicity and lower rate of Grade 1 -2 diarrhea; 28.8%) and outcome.