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Blockchain offers in 2021 a backbone for a new type of internet. As the use of blockchain technology becomes more and more captivating in online retail and much more, it is not surprising that more and more companies are investing in this technology and incorporating it and relying more and more on e-commerce. This article aims to structure the notions involved in blockchain technology and to highlight what the blockchain opportunity in e-commerce really looks like.

In this paper, methods and recommendations for an e-commerce web application of an online e-shop were explored, using various web technologies, such as Python. The approach used is described by analyzing the initial requirements, models and projects of the planned solution and the final implementation of the chosen method using a Model-View-Controller (MVC) framework. To achieve this goal, use case diagrams for specifications and implementation were developed, providing two levels of solutions: basic implementation using cookie functionality and advanced implementation based on the integration of machine learning algorithms. The adequacy and advantages / disadvantages of different methods, such as general recommendation systems and content-based recommendations, were analyzed and presented. This type of implementation is only a first step towards the explicable paradigm of artificial intelligence. Finally, the possibilities for future research are presented, taking into account several applications and other design aspects.

By setting clear targets for reducing pollutant emissions, the researchers in the field of combustion are pushed lately to find new alternatives for cleaner combustion. The partial or total transition to other types of fuels, such as hydrogen, involves substantial changes in the combustion process and possible necessary constructive changes. In the study of the combustion of CH4-H2 mixtures, both numerically and experimentally, preliminary calculations are required, which will help to easily establish the parameters and working regimes and then to use for verifying the results. This paper aims to find an easier method of calculating these parameters, depending on the percentage of gas in the fuel mixture. The calculated values resulted this way will lead to some logical estimates of important aspects of combustion, such as flame field and temperature variation, related to the variation of the amount of hydrogen in the mixture. The method can be a useful tool in the preliminary design of a combustion chamber for CH4-H2 mixtures.

The study focuses on the possible influences of intra (I) lobular (L) stromal compounds [intertubular spaces and seminiferous (S) tubule (T) wall (W)] morphologic changes on S epithelium (E) during ageing process. The material consisted of surgical samples of testicular tissue from 192 patients with orchidectomy for prostate carcinoma. Seven age groups were designed, from 50 to 80 years. Tissue samples were fixed in neutral buffered formalin, embedded in paraffin stained with HE, Goldner and Gömöri and immunomarked (in a subgroup of 28 cases) for smooth muscle actin, collagen IV, and CD34. SE had an uneven involution, both individually and inter-individually, but with normal spermatogenesis in many of ST. E degenerative changes were seen mainly in L periphery. Different stages of maturation arresting were more frequent in older patients. IL septae had changes with extremely variable intensity, dispersed mainly in L periphery, without significant spread and without extensive trend with ageing. Leydig cells showed focal hyperplasia without extensive trend related with ageing. STW presented strictly in the internal layer of lamina propria (apposed to basement membrane of ES) a focal sclerosis, with variable extension concerning its presence, thickness and T circumference (T without sclerosis, with focal sclerosis and with fibro-hyaline "collar" - FHyC) but not related with ageing. IL arteriolae showed focal areas of degeneration with a wide individual and inter-individual range of intensity and extension, but not related with age. Capillary network (CN), with both its peri-T and intramural segments, was present in all age groups, with no quantitative endothelial changes and decreasing only in very old cases. FHyC was often associated with E atrophy. STW focal sclerosis could explain focal degeneration of SE in senescence, although CN undergoes no significant changes.

Synchronous development of a second primary cancer in patients with esophageal squamous cell carcinoma was reported in 2.73%-11% of the cases. Although the synchronous association between esophageal and renal cancer is very rare, an increasingly number of cases is reported in medical literature. This study's aim is to report a case of synchronous esophageal squamous cell carcinoma and an urothelial carcinoma of the right kidney. Patient G.D. was admitted in our clinic with esophageal cancer diagnosis; during the preoperative work-up protocol, an asymptomatic right renal mass was discovered. A nephroureteroscopy with biopsy was performed and the urothelial renal cancer diagnosis was established. The patient is proposed for seriate surgery: nephroureterectomy on the first stage, then esophagectomy with gastric reconstruction was performed. Postoperative evolution was unfavourable, patient being finally discharged, on his request, with severely altered status.