A Case-Matched Analysis of Laparoscopic Liver Resection for Hepatocellular Carcinoma Located in Posterosuperior Segments of the Liver According to Adaption of Developed Techniques.

Background and Objectives: Laparoscopic liver resection (LLR) for the hepatocellular carcinoma (HCC) located in posterosuperior (PS) segment is technically demanding, but has been overcome by accumulated experiences and technological improvements. We analyzed peri-and post-operative results before and after the adaptation of the enhanced techniques. Materials and Methods: We retrospectively reviewed 246 patients who underwent LLR for HCC in PS segments from September 2003 to December 2019. According to the introduction of advanced techniques including intercostal trocars, Pringle maneuver, and semi-lateral French position, the patients were divided into Group 1 (n = 43), who underwent LLR from September 2003 to December 2011, and Group 2 (n = 203), who underwent LLR from January 2012 to December 2019. Among these cases, 136 patients (Group 1 = 34, Group 2 = 102) were selected by case-matched analysis using perioperative variables. Results: Mean operation time (362 min vs. 291 min) and hospital stay (11 days vs. 8 days, p = 0.023) were significantly longer in Group 1 than Group 2. Otherwise, disease-free survival (DFS) rate was shorter and resection margin (1.3 mm vs. 0.7 mm, p = 0.034) were smaller in Group 2 than Group 1. However, there was no difference in type of complication (p = 0.084), severity of complication graded by the Clavien-Dindo grade system (p = 0.394), and 5-year overall survival (OS) rates (p = 0.986). In case-matched analysis, operation time (359 min vs. 266 min p = 0.002) and hospital stay (11.5 days vs. 8.0 days, p = 0.032) were significantly different, but there was no significant difference in resection margin, DFS, and OS. Conclusions: The adaptation of improved techniques has reduced the complexity of LLR in PS segments.

Analysis of structure and P-c-T curve of hydrogenated Ti53Zr27xNi20Pd(x) quasicrystals.

The potential application of TiZrNi quasicrystals was evaluated by measuring the pressure-composition-temperature curves after replacing Zr by Pd to the limit maintaining the host structure for the samples made with Ti53Zr27(-x)Ni20Pd(x), where 0 < or = x < or = 8. The results of X-ray diffraction data revealed that the samples keep the pure quasicrystal structure to the maximum value of x = 8. All diffracted peaks uniformly shifted to the low angle of 2 theta in X-ray diffraction pattern suggesting that hydrogen atoms homogeneously diffuse in the quasicrystals and uniformly expand the quasilattice constants without modification of the structure. After hydrogenation at elevated temperature, the quasi-lattice constants increased from 5.12 to 5.34 angstroms for the samples made with x = 0 without appearing an impurity phase. When Zr was replaced by 8 at.% of Pd, the equilibrium vapor pressures significantly increased to 3.41 from 0.41 Torr at 300 degrees C although the total amount of hydrogen decreased as increasing Pd concentration. These results demonstrate that Pd will play a critical role in application for the TiZrNi quasicrystals as hydrogen storage materials.

Magnetic properties of hydrogen-included TiZrNiPd quasicrystals.

Quasicrystals prepared by rapid quenching of Pd-added TiZrNi ingots were hydrogenated, and effects of hydrogen for magnetic properties were compared with the unhydrogenated ones under magnetic fields from -10000 to 10000 Oe. The magnetization values obtained from vibrating sample magnetometer (VSM) were analyzed with the combination of powder X-ray diffraction (XRD) data. While its contribution is larger than that of Pd, hydrogen decreases the magnetic moments of both Pd-doped and undoped quasicrystals. As increasing the amount of absorbed hydrogen which is represented by H/M (hydrogen to host metal atom ratio) values from 0 to 1.19, the magnetization values of Ti53Zr27Ni20 quasicrystals measured at 10000 Oe significantly decreased from 0.301 to 0.212 emu/g. A careful analysis of XRD data demonstrated that the reduced interactions of magnetic dipole moments between Ni atoms, as the product of the expansion of the quasilattice constants after hydrogenation, are responsible for the decreased magnetization values in hydrogenated TiZrNiPd quasicrystal samples.

Hydrogen absorption and structural analysis of TiZrNiV quasicrystals.

Ti-based quasicrystals are known to store a high capacity of hydrogen exceeding the density of liquid hydrogen. Because TiZrNi quasicrystals contain a large number of tetrahedral sites formed with Ti and Zr atoms that are chemically favorable to hydrogen, these materials retain strong advantages for hydrogen storage applications in structurally and chemically. In fact, TiZrNi quasicrystals are known to absorb hydrogen maximum of the hydrogen to host metal ratio (H/M) value of near 2.0. The critical disadvantage, however, is that the equilibrium vapor pressure of hydrogen is very low (less than 1 Torr). To overcome this engineering drawback, we added a small amount of vanadium (V) in Ti(53-x)Zr27Ni20V(x), alloys (where x = 0 to 15) and rapidly quenched the molten ingots to form quasicrystals, and investigated the effects of V in terms of changes of structure, the H/M values, and an equilibrium vapor pressure of hydrogen. As the results, an equilibrium vapor pressure significantly increased from 0.84 to 2.16 Torr while the maximum H/M value decreased from 1.32 to 1.11 as increasing x = 0 to 8. After hydrogenation, the main peaks shifted evenly to the lower angle of 20 in X-ray diffraction patterns with uniform expansion of the quasilattice constants which demonstrates that hydrogen atoms homogeneously diffused into the samples. A Laves phase starts to form at x = 13 and the samples completely transformed to the phase at x = 15 suggesting the similarity between the quasicrystal and the Laves phase.