The Comparison of Two Versus More Than Two Tracts Percutaneous Nephrolithotomy for the Management of Staghorn Calculi

Objective:In this study, we evaluated the outcomes of two tracts and more than two tracts for percutaneous nephrolithotomy (PCNL) performed in patients with staghorn calculus.Method:We performed multi-tract PCNL on 132 patients with staghorn calculi, whose stone burdens varied between 7 and 28.2 cm2 in our clinics between March 2015 and August 2019. We compared the outcomes and complications of multi-tract PCNL in two groups of patients. Group 1 included patients with two percutaneous tracts, while the patients in group 2 had more than two percutaneous tracts. Stone surface areas and locations were preoperatively recorded. Intraoperative data included number of tracts, blood transfusion rates and operative times. Postoperative stone-free rates (SFR) were also investigated.Results:Group 1 included 93 patients, while group 2 included 39. The mean stone burden (MBS) was 10.4 cm2 in group 1 and 11.3 cm2 in group 2, with no statistical difference. Blood transfusion rates were 22.5% (21/93) in group 1 and 46.1% (18/39) in group 2 (p<0.05). The mean operative times were 135 min in group 1 and 168 min in group 2. SFR were 74.1% (69/93) and 74.3% (29/39), respectively, and there was no significant difference (p=0.93). Major complications were recorded in 4 patients (3.4%). In group 2, two patients had undergone angioembolization due to A-V fistula, and intubated thoracostomy was performed on 1 patient due to the development of hydropneumothorax.Conclusion:Our study has demonstrated that performing more than 2 tracts for complete clearance of stones does not significantly increase SFR. In addition, increasing number of tracts is associated with higher blood transfusion rates, prolonged operative times and enhanced complication rates

Theoretical evaluation of the melting efficiency for the single-screw micro-extrusion process : the case of 3D printing of ABS

One of the challenges for single-screw micro-extrusion or additive manufacturing (AM), thus 3D printing, of polymers is controlling the melting efficiency so that energy and equipment costs can be minimized. Here, a numerical model is presented for AM process design, selecting acrylonitrile-butadiene-styrene (ABS) as viscoelastic reference polymer. It is demonstrated that AM melting is different compared to conventional melting due to variation in extrusion dimensions, leading to a different balance in heating by conduction and viscous heat dissipation as caused by the shearing between the melt layers in the associated film layer near the barrel. The thickness of this melt film layer is variable along the screw length, and it is shown that simplified models assuming an overall average value are too approximate. It is highlighted that the screw frequency, pitch angle and compression ratio are important process parameters to control the point of melt finalization. In addition, the power-law index reflecting the shear thinning nature of the polymer melt is showcased as a key parameter. Moreover, AM process results assuming constant and temperature dependent specific heat capacities and thermal conductivities are compared. The current work opens the door for on-line AM process control, addressing all relevant operating and material parameters

Segregation formation, thermal and electronic properties of ternary cubic CdZnTe clusters: MD simulations and DFT calculations

Surface and core formation, thermal and electronic properties of ternary cubic CdZnTe clusters are investigated by using classical molecular dynamics (MD) simulations and density functional theory (DFT.) calculations. In this work, MD simulations of the CdZnTe clusters are performed by means of LAMMPS by using bond order potential (BOP). MD simulations are carried out at different temperatures to study the segregation phenomena of Cd, Zn and Te atoms, and deviation of clusters and heat capacity. After that, using optimized geometries obtained, excess charge on atoms, dipole moments, highest occupied molecular orbitals, lowest unoccupied molecular orbitals, HOMO-LUMO gaps (E-g), total energies, spin density and the density of states (DOS) have been calculated with DFT. Simulation results such as heat capacity and segregation formation are compared with experimental bulk and theoretical results

Mechanical properties of CdZnTe nanowires under uniaxial stretching and compression: A molecular dynamics simulation study

Structural and mechanical properties of ternary CdZnTe nanowires have been investigated by performing molecular dynamics simulations using an atomistic potential. The simulation procedures are carried out as uniaxial stretching and compression at 1 K and 300 K. The results demonstrate that the mechanical properties of CdZnTe ternary nanowires show significantly a dependence on size and temperature under uniaxial stretching and compression

Antik dönemde eğitim ve okul yapıları üzerine

The education and instruction of children and young people has been an important topic that families, various communities, and societies have been closely involved in throughout the history. One of the most important places of education and instruction, especially until the modern age, was undoubtedly the home and the close environment, where children live with their families. The instructor/teacher would come home and teach there. Another important place has been the temple, as seen in many different religions today. The temple architectures of various religions included sections that were specifically created for that purpose. But through the human history there also appeared educational/instructional institutions featuring a certain architecture, besides residences and temples. Undoubtedly, one of the most notable of the above was the ancient Hellenic gymnasium, which beyond being an eponym for modern western educational institutions, also proved to be an ideal model (for example, in today's Germany, the name of the institution that corresponds to the high school in Turkey is "Gymnasium"). Over time, gymnasions were transformed from places, where mostly physical training was conducted and warfare were taught, to places, where the literacy skills were acquired and where intellectual development was attained. Essentially, the blended education system, if the term is appropriate, determined the architecture of gymnasions. Especially after the end of the 4th century BC, the gymnasions, which started to take shape in architectural terms, gained almost a standard structure appearance in the following centuries and turned into institutions that each of the ancient cities of the Eastern Mediterranean had at least one. In addition, as an indication of their importance gymnasions became the representation areas of kings and city elites. The architectural reflections of the said importance and the desire to create representation can still be observed after 2000 years, especially in many gymnasion buildings in Anatolia.No sponso

Antik dönemde eğitim ve okul yapıları üzerine

The education and instruction of children and young people has been an important topic that families, various communities, and societies have been closely involved in throughout the history. One of the most important places of education and instruction, especially until the modern age, was undoubtedly the home and the close environment, where children live with their families. The instructor/teacher would come home and teach there. Another important place has been the temple, as seen in many different religions today. The temple architectures of various religions included sections that were specifically created for that purpose. But through the human history there also appeared educational/instructional institutions featuring a certain architecture, besides residences and temples. Undoubtedly, one of the most notable of the above was the ancient Hellenic gymnasium, which beyond being an eponym for modern western educational institutions, also proved to be an ideal model (for example, in today's Germany, the name of the institution that corresponds to the high school in Turkey is "Gymnasium"). Over time, gymnasions were transformed from places, where mostly physical training was conducted and warfare were taught, to places, where the literacy skills were acquired and where intellectual development was attained. Essentially, the blended education system, if the term is appropriate, determined the architecture of gymnasions. Especially after the end of the 4th century BC, the gymnasions, which started to take shape in architectural terms, gained almost a standard structure appearance in the following centuries and turned into institutions that each of the ancient cities of the Eastern Mediterranean had at least one. In addition, as an indication of their importance gymnasions became the representation areas of kings and city elites. The architectural reflections of the said importance and the desire to create representation can still be observed after 2000 years, especially in many gymnasion buildings in Anatolia.No sponso

Structural and Electronic Properties of ZnmCdn,Te-k (m plus n plus k=2-4) Clusters: DFT Calculations

The structural and electronic properties of isolated neutral Zn-m,Cd-n Te-k, clusters for m + n+ k = (2 - 4) have been investigated by performing density functional theory calculations at B3LYP/CEP-121G level. The electronic ground state has been found to be spin triplet for the clusters Te-2, CdTe, ZnTe2, and CdTe2, the rest have been found to have a spin singlet state. The optimum geometries, charge density, spin density, electrostatic potential, excess charge on atoms, dipole moments, vibration frequencies, highest occupied molecular orbitals, lowest unoccupied molecular orbitals, HOMOLUMO gaps (E-g), the possible dissociation channels and the corresponding dissociation energies of the clusters considered have been obtained. The energy gap (E-g) decreases with increasing number of atoms in the clusters