Radiographic appearance and clinical implications of the presence of radix entomolaris and radix paramolaris

Background: The variation in mandibular molars’ anatomy is not as rare as it might appear to be. Depending on the location of the additional root found in a mandibular molar, it may be referred to as either radix entomolaris (RE) or radix paramolaris (RP). The aim of the study was to present radiographic appearance of RE and RP and indicate the clinical implications of its presence. Materials and methods: The material consisted of 3,000 panoramic and 300 periapical radiographs of first and second mandibular molars taken in the Department of Dental and Maxillofacial Radiodiagnostics of the Medical University in Lublin which were screened for RE and RP. Results: Among panoramic and periapical radiographs only 14 cases of additional roots were found: 11 teeth with RE/RP in the Polish population and 3 in Taiwanese. Only 2 panoramic radiographs revealed the presence of RE and surprisingly the occurrence was bilateral. Conclusions: Dentists should not be taken by surprise at finding an additional root in mandibular molars. They should be aware of the anatomical diversity of these teeth and know how to recognise possible extra roots during radiograph reading.

Early postnatal development of the lumbar vertebrae in male Wistar rats: double staining and digital radiological studies

The aim of the study was to evaluate the physiological developmental changes of male rats’ lumbar vertebrae during the first 22 days after birth. Morphology and mineralisation of lumbar vertebrae were evaluated using double-staining and digital radiography system, which allowed vertebral width and optical density to be determined. Pup weight, crown-rump length, body mass index and vertebral width increased during postnatal period and significantly correlated with their age. Bone mineralisation, as measured by optical density, did not show any significant differences. The complete fusion of the primary ossification centres had a cranio- -caudal direction and started on day 19 after parturition but was incomplete by day 22. It could be concluded that, unlike significant age-related increase of vertebral size, mineralisation was only slightly elevated during evaluated postnatal period. The method described is supplementary to alizarin red S staining as it provides both qualitative and quantitative data on mineralisation in a similar manner to micro computed tomography but does not allow 3 dimensional and microarchitecture examination

Anatomical classification of the shape and topography of the operated stomach

The aim of the study was to present the classification of anatomical variances of the operated stomach, based on the radiological and historical data. Different anatomical variations of the operated organ were revealed in 431 out of 2034 patients examined in years 2006-2010. Four primary groups were established: abnormal position along longitudinal (I) and horizontal axis (II), as well as abnormal shape (III) and stomach connections (IV). An additional group (V) encloses mixed forms that connect features of two or more primary groups. The first group contains the partial and total translocation of the stomach into the thoracic cavity after the partial or total esophagectomy. Depends on the applied surgical techniques used during the total esophagectomy, the stomach could be located in the front or back to the pericardial sac. An elongated and gestrectatical form often with signs of pylorostenosis is visible in patients treated by the vagotomy. The consequences of fundoplication included: lack or narrow cardiac angle, and often mild form of the stomach cascade. The most common abnormal shape of the stomach was secondary to the gastrectomy and gastric bending. The final organ shape depends on the type of applied surgical procedure that maintains physiological connection with the duodenum or un-anatomical one, mostly with the jejunal loop. In banding, the body of the stomach forms hourglass on the level of the artificial adjustable band, typically fitted for the surgical slim purpose

Numerical analysis of the state of the effort of the screw connection

Celem badawczym było określenie stopnia wytężenia zachodzącego w połączeniu śrubowym po przekroczeniu granicy plastyczności materiału. Model trójwymiarowy przygotowano w oprogramowaniu CatiaV5R21, natomiast gotową geometrię zaimportowano do środowiska Abaqus 6.14, celem wykonania analizy MES. Zakres pracy obejmował analizę numeryczną w stanie ustalonym, przy odpowiednio zdefiniowanych warunkach brzegowych zgodnych ze stanem rzeczywistym połączenia. Przeprowadzona analiza miała na celu odwzorowanie rzeczywistego procesu dokręcania śruby poprzez siłę przyłożoną do klucza. Badanie numeryczne pozwoliło na dokładne określenie miejsc newralgicznych układu, przy jednoczesnej konfrontacji z dopuszczalnymi granicami wytrzymałości materiału.The aim of the test was to determine the effort of setting the screw connection beyond the yield strength of the material. 3D model prepared in the software CatiaV5R21, while ready geometry imported into Abaqus 6.14 environment. The scope of work included numerical analysis in steady state, when properly defined boundary conditions reflect the current real connection. The analysis was aimed at mapping the actual process of tightening by the force applied to the key. Numerical study enabled the precise locations of critical system in addition to the confrontation with the permissible limits of material strength

Numerical analysis of the level of stress in the car scissor jack

W artykule ukazano poziom krytycznych naprężeń występujących w podnośniku trapezowym BD-02B2. Model wstępny wykonano w Catii v5, natomiast badania MES przeprowadzono w środowisku Abaqus 6.10. Poziom naprężeń przedstawiono w większości elementów, a główna uwagę skupiono na podzespołach, których wartości na-prężeń przekroczyły granicę plastyczności pod zadanym obciążeniem. Naprężenia zostały wywołane siłą osiową działająca bezpośrednio na koronę podnośnika. Analiza numeryczna pozwoliła na wyodrębnienie newralgicznych obszarów w obrębie badanego modelu. Analizy MES stanowią potężne narzędzie służące obliczeniom wytrzymałościowym konstrukcji. Wyznaczone rozkładu napręęeń zredukowanych według hipotezy wytrzymałościowej Hubera-Misesa-Hencky’ego konfrontowano z właściwościami materiałowymi modelu. Obliczenia numeryczne stanowiły podstawę do określenia stanu wytrzymałości mechanizmu.In the article shown the critical stress level occurring in the scissor jack BD-02B2. Preliminary model performed in CATIA V5, while the MES tests carried out in an Abaqus 6.10. Stress levels are shown in most of the designed elements. the main attention is focused on components whose values of the stress exceed the yield strength at a given load. The stresses are induced by axial force acting directly on the crown of scissor jack. Numerical analysis allowed for isolating sensitive areas within the tested model. FEA provide a powerful tool for structural strength calculations . Reduced stress distribution determined by testing the hypothesis Huber-Mises-Hencky were compared with the material properties of the model. Numerical calculations were the basis to determine the strength of the mechanism

Fem and Experimental Analysis of Thin-Walled Composite Elements Under Compression

Thin-walled steel elements in the form of openwork columns with variable geometrical parameters of holes were studied. The samples of thin-walled composite columns were modelled numerically. They were subjected to axial compression to examine their behavior in the critical and post-critical state. The numerical models were articulately supported on the upper and lower edges of the cross-section of the profiles. The numerical analysis was conducted only with respect to the non-linear stability of the structure. The FEM analysis was performed until the material achieved its yield stress. This was done to force the loss of stability by the structures. The numerical analysis was performed using the ABAQUS® software. The numerical analysis was performed only for the elastic range to ensure the operating stability of the tested thin-walled structures

Badania stateczności i stanów pokrytycznych ściskanych cienkościennych profili kompozytowych

The object of this study is a thin-walled channel-section profile made of a carbon-epoxy composite subjected to axial compression. The study included analysis of the critical and weakly post-critical behaviour using experimental and numerical methods. As a result of the research conducted on a physical model of the structure, we determined a post-critical equilibrium path, which was then used to determine the critical load by approximation methods. Simultaneously, numerical calculations were performed by the finite element method. Their scope included a linear analysis of eigenvalue problems, the results of which led to determination of the critical load for the developed numerical model. The second step of the calculations consisted in performing a nonlinear analysis of the structure with geometrically initiated imperfection corresponding to the lowest buckling mode of the investigated profile. The numerical results were compared with the experimental findings, revealing that the developed numerical model of the structure was correct. The numerical simulations were performed using the ABAQUS® software.Przedmiotem badań jest cienkościenny profil o przekroju ceowym, wykonany z kompozytu węglowo-epoksydowego, poddany osiowemu ściskaniu. Zakres badań obejmował analizę stanu krytycznego i słabo pokrytycznego metodami doświadczalnymi i numerycznymi. W wyniku badań prowadzonych na fizycznym modelu konstrukcji wyznaczono pokrytyczną ścieżkę równowagi, na podstawie której z wykorzystaniem metod aproksymacyjnych określono wartość obciążenia krytycznego. Równolegle prowadzono obliczenia numeryczne z wykorzystaniem metody elementów skończonych. Zakres obliczeń obejmował liniowa analizę zagadnienia własnego, w wyniku której określono wartość obciążenia krytycznego modelu numerycznego konstrukcji. Drugi etap obliczeń obejmował nieliniową analizę stanu słabo pokrytycznego konstrukcji z zainicjowaną imperfekcją geometryczną, odpowiadającą najniższej postaci wyboczenia konstrukcji. Wyniki obliczeń numerycznych porównano z wynikami badań doświadczalnych, potwierdzając adekwatność opracowanego modelu numerycznego konstrukcji. Zastosowanym narzędziem numerycznym był program ABAQUS®

Experimental and numerical analysis of the compression thin-walled composite plate

The subject of research is a rectangular plate with a cut-out subjected to regular compression. The plate articulately supported on the short side edges, made of a composite with high strength properties. The study concerned the numerical finite element analysis linear and nonlinear stability of the structure and the experimental validation of the results. The instrument used was a numerical program ABAQUS®