Effect of Temperature on the Cyclic Fatigue Resistance and Phase Transformation Behavior of Three Different NiTi Endodontic Instruments.

Background This study aims to analyze the phase transformation behavior and evaluate the effect of different temperatures on the fracture strength of files. Methodology A total of 108 files were used, and cyclic fatigue tests were performed on HyFlex EDM, VDW.ROTATE, and TruNatomy at three different temperatures (+4°C, +35°C, and +60°C) The time to fracture of files was measured, and the number of cycles was calculated. In addition, the fractured fragment lengths were measured. The Kruskal-Wallis test was used to compare the data that were not normally distributed according to groups. The Mann-Whitney U test was performed for comparisons. P-values <0.05 were considered statistically significant. Results As the temperature increased for all files, the number of cycles to fracture (NCF) decreased. NCF was significantly higher for ROTATE at 4°C and 60°C and HyFlex EDM at 35°C. Conclusions The resistance to cyclic fatigue in all files decreased significantly as the temperature increased.

Investigation of (n,2n) reaction cross sections on Pd and Cd isotopes using equilibrium and pre-equilibrium models.

We have carried out calculations for cross sections of 102Pd(n,2n)101Pd, 110Pd(n,2n)109Pd, 106Cd(n,2n)105Cd, 108Cd(n,2n)107Cd, 110Cd(n,2n)109Cd, 114Cd(n,2n)113Cd and 116Cd(n,2n)115Cd reactions via nuclear models which are based on the equilibrium and pre-equilibrium emissions in the interactions of nuclei with neutron particles. The cross sections were determined by means of the model codes EMPIRE 3.2, ALICE/ASH and TALYS 1.8. Besides, the equilibrium and pre-equilibrium effects were performed using Weisskopf-Ewing model, Geometry Dependent Hybrid model, Exciton model and Two-component Exciton model at neutron energies from threshold to 20 MeV. Effects of different level density models on the equilibrium calculations have also been discussed. Furthermore, the empirical systematics, which were suggested in our previous study and in the literature, were used to calculate the (n,2n) cross sections at energies around 14.5 MeV. Thereby, the data obtained were discussed and compared with the measured data in the literature.

Microvascular proliferation of brain metastases mimics glioblastomas in squash cytology.

OBJECTIVE: Although microvascular proliferation is a key feature in the diagnosis of high-grade glioma, the characteristics of metastatic tumour vessels in smear preparations have not been documented. In this study, the vascular changes in metastatic brain tumours, using squash cytology to examine the vascular patterns in brain metastases, were reviewed. METHODS: One hundred and forty-three squash smears of brain tissue, including 25 normal or reactive tissue, 23 malignant lymphomas, 8 grade I glioma (pilocytic astrocytoma), 23 grade II glioma (diffuse astrocytoma and oligodendroglioma), 42 grade IV glioma (glioblastoma), and 22 metastasis, were assessed. Two vascular patterns were assessed: thick and branching, and glomeruloid. The vessel density, nuclear layer and the number of vessel branches were compared. Furthermore, tumour vessels of brain metastases were analysed by histology and for immunohistochemical expression of CD34, α-smooth muscle actin (SMA) and high-molecular-weight caldesmon (h-CD). RESULTS: Among 22 metastatic tumours, thick and branching vessels were found in 17 (77%) and glomeruloid vessels in 13 (59%). These incidences of microvascular proliferation patterns were similar to those of glioblastomas or pilocytic astrocytomas. Vessel density, nuclear layer and vessel wall branches were significantly higher in metastatic tumours than malignant lymphomas, grade II gliomas or normal brain tissues. Glomeruloid vessels consisted of CD34-positive cells and α-SMA-positive cells, and α-SMA-positive cells had a low h-CD expression. These immunohistochemical patterns were similar to those of high-grade gliomas. CONCLUSIONS: The vascular features of metastatic brain tumours are similar to those of glioblastomas, suggesting that these microvascular proliferations contribute to the progression of metastatic tumours.

Gross anatomy of the pancreatic lobes and ducts in six breeds of domestic ducks and six species of wild ducks in China.

A previously unreported pancreatic duct was found by Liu (1989) in Pekin ducks. This duct has now been consistently found in six breeds of domestic ducks and six species of wild ducks in China. For purposes of Nomina Anatomica Avium it is hereby called the 'first pancreatic duct' (Ductus pancreaticus primus) since it enters the duodenum at or near the flexure where the descending duodenum becomes the ascending duodenum. All other pancreatic ducts enter the duodenum later, closer to where it joins the jejunum. This first pancreatic duct drains the caudal extremity of the dorsal lobe of the pancreas and can be easily exteriorized for experimental purposes. Within the parenchyma of the dorsal lobe of the pancreas this duct communicates with the dorsal pancreatic duct. In the present study of the gross anatomy of the pancreatic lobes of domestic and wild Chinese ducks we describe and illustrate variations in position and number of all biliary and pancreatic ducts.