Robust topological designs for extreme metamaterial micro-structures.

We demonstrate that the consideration of material uncertainty can dramatically impact the optimal topological micro-structural configuration of mechanical metamaterials. The robust optimization problem is formulated in such a way that it facilitates the emergence of extreme mechanical properties of metamaterials. The algorithm is based on the bi-directional evolutionary topology optimization and energy-based homogenization approach. To simulate additive manufacturing uncertainty, combinations of spatial variation of the elastic modulus and/or, parametric variation of the Poisson's ratio at the unit cell level are considered. Computationally parallel Monte Carlo simulations are performed to quantify the effect of input material uncertainty to the mechanical properties of interest. Results are shown for four configurations of extreme mechanical properties: (1) maximum bulk modulus (2) maximum shear modulus (3) minimum negative Poisson's ratio (auxetic metamaterial) and (4) maximum equivalent elastic modulus. The study illustrates the importance of considering uncertainty for topology optimization of metamaterials with extreme mechanical performance. The results reveal that robust design leads to improvement in terms of (1) optimal mean performance (2) least sensitive design, and (3) elastic properties of the metamaterials compared to the corresponding deterministic design. Many interesting topological patterns have been obtained for guiding the extreme material robust design.

Isotope-specific breath analysis to track the end-stage renal disease during hemodialysis.

The underlying mechanisms towards the progression of end-stage renal disease (ESRD) in chronic kidney disease (CKD) are poorly understood and it still remains a major clinical stumbling block for early detection of CKD. Most patients with CKD pass through ESRD with the necessity of frequent hemodialysis (HD) treatment. At present, plasma urea and creatinine levels are examined in most CKD patients to monitor their health status after dialysis. But it is impossible to get immediate feedback on the patients' health as the conventional tests involve the collection of blood samples, laboratory processing for a prolonged period of time and, finally, analysis of those samples. However, the test results are very important in deciding the treatment plan for those ESRD patients. Here, we show that the enzymatic activity of carbonic anhydrase in erythrocytes is distinctly altered in ESRD subjects under HD. This, in turn, leads to the isotopic enrichments of oxygen-18 (18O) and carbon-13 (13C) of CO2 during respiration in HD treatment. High-resolution cavity-enhanced absorption spectroscopic measurements show that 18O and 13C-isotopic fractionations of breath CO2 are correlated with Kt/V values, suggesting a novel unifying strategy for ESRD patients that can be used as an isotope-specific methodology for non-invasive assessment of dialysis adequacy and hence 12C18O16O and 13C16O16O could be used as novel markers for tracking the physiological parameters of ESRD individuals. Our findings suggest that the monitoring of 18O and 13C isotopes of breath CO2 may facilitate the proper management of advanced CKD patients. The primary advantage of this isotopic breath test is that it may reduce the valuable time lag between the completion of dialysis and obtaining the clinical report on the status of patients' health.

Gestational trophoblastic tumor at a tertiary level cancer center: a retrospective study.

OBJECTIVE: To retrospectively analyze gestational trophoblastic disease at a tertiary level cancer center. STUDY DESIGN: Thirty-six cases of gestational trophoblastic tumor at a tertiary level cancer hospital during the period 1996-2004 were studied. Various epidemiologic features were studied, diagnosed an and patients were classified according to the International Federation of Gynecology and Obstetrics scoring system. Chemotherapy was the main mode of treatment. RESULTS: There was 100% success in low-risk cases and 90% success in high-risk cases. CONCLUSION: Gestational trophoblastic tumors have an excellent prognosis if diagnosed and treated in time, and the potential for childbearing can be maintained.