Abnormal Optoelectric Properties of Two-Dimensional Protonic Ruthenium Oxide with a Hexagonal Structure

Two-dimensional structures can potentially lead to not only modulation of electron transport but also the variations of optical property. Protonic ruthenium oxide, a two-dimensional atomic sheet material, has been synthesized, and its optoelectric properties have been investigated. The results indicate that protonic ruthenium oxide is an excellent candidate for use as a flexible, transparent conducting material. A hydrated-ruthenium-oxide sheet has been first prepared via the chemical exfoliation of sodium intercalated ruthenium oxide (NaRuO₂) and, subsequently, converted into a protonic ruthenium oxide sheet using thermal treatment. A thermally activated transport mechanism is dominant in hydrated ruthenium oxide but diminishes in protonic ruthenium oxide; this resulted in a high electrical conductivity of ∼200 S/cm of the protonic sheet. Because of the unique interband and intraband structure, protonic ruthenium oxide has a small optical absorption coefficient of ∼1.62%/L. Consequently, such high conductivity and low absorption coefficient of protonic ruthenium oxide results in excellent transparent conducting properties

Clinical Characteristics and Outcomes of Gastric Cancer Patients Aged over 80 Years: A Retrospective Case-Control Study

<div><p>Background and Aims</p><p>The average human life expectancy is increasing worldwide, thus the proportion of elderly gastric cancer patients is also increasing. In this case-control study, we investigated the clinical and oncologic outcomes of gastric cancer in patients over 80 years old.</p><p>Methods</p><p>From January 2004 to December 2010, 291 patients aged over 80 years old (case group) were diagnosed and treated with gastric cancer at Asan Medical Center, Seoul, Korea. From the same period, 291 patients aged 18 to 80 years old were selected as the control group. The clinical findings and clinical outcomes of gastric cancer were retrospectively reviewed and compared between the two groups.</p><p>Results</p><p>There were significant differences in the overall 5-year survival rate between the case and control groups (30.9% vs. 73.8%, respectively; P<0.001). In patients who received the curative treatment, overall 3- and 5-year survival rates showed 74.3% and 57.9% in case group and 91.6% and 86.5% in the control group. When analysis was confined to resectable elderly patients with a favorable performance, the curative resection group showed significantly better overall 3- and 5-year survival rates than the conservative treatment group (73.7% and 58.8% vs. 29.8% and 0%, respectively).</p><p>Conclusions</p><p>Although elderly gastric cancer patients show an advanced stage at diagnosis and poor prognosis compared with non-elderly patients, elderly patients with good performance could benefit from curative resection. Thus, the clinical decision whether to undergo curative resection or conservative management should be made on an individualized basis.</p></div

Flow chart of patients included in this study.

<p>A total of 291 patients aged over 80 years were included, and another 291 patients aged 80 years or younger were randomly selected as a control group. Op, operation; ER, endoscopic resection; CTx, chemotherapy; BSC, best supportive care.</p

Baseline clinical and pathologic characteristics of gastric cancer in the case and control groups.

<p>Baseline clinical and pathologic characteristics of gastric cancer in the case and control groups.</p

Kaplan–Meier estimates of survival rates in resectable elderly patients with a favorable performance (ASA score 1 or 2) according to the treatment modality.

<p>The curative resection group showed better survival than the conservative treatment group (<i>P</i><0.001).</p

Univariate and multivariate analyses of prognostic factors of overall mortality in gastric cancer patients aged over 80 years.

<p>Univariate and multivariate analyses of prognostic factors of overall mortality in gastric cancer patients aged over 80 years.</p

Cumulative survival rates between case and control groups.

<p><b>(A)</b> Kaplan–Meier survival curve showing a significant difference in overall survival between the control and case groups (<i>P</i><0.001). <b>(B)</b> Kaplan–Meier estimates of overall survival rates in patients of the control and case groups according to the tumor stage. The case group showed significantly lower survival rates at each stage than the control group (stage I, <i>P</i><0.001; stage II, <i>P</i> = 0.006; stage III, <i>P</i><0.001; and stage IV, <i>P</i><0.001).</p

Oncologic outcomes according to the treatment modality.

<p>Oncologic outcomes according to the treatment modality.</p

Oncologic outcomes of gastric cancer in the case and control groups.

<p>Oncologic outcomes of gastric cancer in the case and control groups.</p