Micro Injection-Molding of Cyclic Olefin Copolymer Using Metallic Glass Insert

There is shift in trend towards the use of high quality polymers as the base material in manufacturing microfluidic chips. In this paper, an amorphous metallic alloy mold insert was used in a micro injection-molding process to fabricate microfluidic features onto cyclic-olefin-copolymer (COC) material. The insert and fabricated samples were compared in terms of the geometry and surface roughness attained. Findings indicate that replication, in general, was possible but the microfeatures formed had significant flashing and tearing at the edges.Singapore-MIT Alliance (SMA

Superlattice Growth via MBE and Green’s Function Techniques

A model has been developed to simulate the growth of arrays consisting of a substrate on which alternating layers of quantum dots (QDs) and spacer layers are epitaxially grown. The substrate and spacer layers are modeled as an anisotropic elastic half-space, and the QDs are modeled as point inclusions buried within the half-space. In this model, the strain at the free surface of this half-space due to the buried point QDs is calculated, and a scalar measure of the strain at the surface is subsequently determined. New point QDs are placed on the surface where the previously calculated scalar strain measure is a minimum. Following available DFT results, this scalar strain measure is a weighted average of the in-plane strains. This model is constructed under the assumption that diffusional anisotropy can be neglected, and thus, the results are more in agreement with results from experiments of growth of SiGe QDs than experiments involving QDs of (In,Ga)As

Toward an internally consistent astronomical distance scale

Accurate astronomical distance determination is crucial for all fields in astrophysics, from Galactic to cosmological scales. Despite, or perhaps because of, significant efforts to determine accurate distances, using a wide range of methods, tracers, and techniques, an internally consistent astronomical distance framework has not yet been established. We review current efforts to homogenize the Local Group's distance framework, with particular emphasis on the potential of RR Lyrae stars as distance indicators, and attempt to extend this in an internally consistent manner to cosmological distances. Calibration based on Type Ia supernovae and distance determinations based on gravitational lensing represent particularly promising approaches. We provide a positive outlook to improvements to the status quo expected from future surveys, missions, and facilities. Astronomical distance determination has clearly reached maturity and near-consistency.Comment: Review article, 59 pages (4 figures); Space Science Reviews, in press (chapter 8 of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Age

First-principles calculation of the effect of strain on the diffusion of Ge adatoms on Si and Ge (001) surfaces

First-principles calculations are used to calculate the strain dependencies of the binding and diffusion-activation energies for Ge adatoms on both Si(001) and Ge(001) surfaces. Our calculations reveal that the binding and activation energies on a strained Ge(001) surface increase and decrease, respectively, by 0.21 eV and 0.12 eV per percent compressive strain. For a growth temperature of 600 degrees C, these strain-dependencies give rise to a 16-fold increase in adatom density and a 5-fold decrease in adatom diffusivity in the region of compressive strain surrounding a Ge island with a characteristic size of 10 nm.Comment: 4 pages, 4 figure

Benefits of vertical and horizontal seismic isolation for LMR (liquid metal reactor) nuclear reactor units

Seismic isolation has been shown to be able to reduce transmitted seismic force and lower response accelerations of a structure. When applied to nuclear reactors, it will minimize seismic influence on the reactor design and provide a design which is less site dependent. In liquid metal reactors where components are virtually at atmospheric pressure but under severe thermal conditions, thin-walled structures are generally used for primary systems. Thin-walled structures, however, have little inherent seismic resistance. The concept of seismic isolation therefore offers a viable and effective approach that permits the reactor structures to better withstand thermal and seismic loadings simultaneously. The majority of published work on seismic isolation deals with use of horizontal isolation system only. In this investigation, however, local vertical isolation is also provided for the primary system. Such local vertical isolation is found to result in significant benefits for major massive components, such as the reactor cover, designed to withstand vertical motions and loadings. Preliminary estimations on commodity savings of the primary system show that, with additional local vertical isolation, the savings could be twice that estimated for horizontal isolation only. The degree of effectiveness of vertical isolation depends on the diameter of the reactor vessel. As the reactor vessel diameter increases, the vertical seismic effects become more pronounced and vertical isolation can make a significant contribution

Lower Variability of Tacrolimus Trough Concentration After Conversion From Prograf to Advagraf in Stable Kidney Transplant Recipients

Backgrounds. Variability of blood trough concentration (C(o)) in immunosuppressant leads to rejection and graft loss after kidney transplantation. Methods. The aim of this study is to prospectively investigate the change of within-patient variability among stable kidney transplant recipients with conversion from twice-daily Prograf to the same milligram-for-milligram daily dose of once-daily Advagraf. Results. The mean age of 129 patients was 51.3 +/- 12.1 years. The conversion to Advagraf was administrated at 6.3 +/- 4.8 years after transplantation. The daily dose was changed from 4.7 +/- 2.0 mg to 4.9 +/- 2.1 mg after conversion. Only six patients increased daily dose by 16.7% to 25% to maintain target levels. The whole blood C(o) of tacrolimus before conversion was 5.9 +/- 1.7 ng/mL. The mean C(o) was significantly reduced after conversion to Advagraf; it was 4.9 +/- 1.5 ng/mL on the seventh day (P<0.001) and 5.4 to 5.5 ng/mL at 1 to 6 months (P<0.05). Forty-one (31.8%) patients have reduced C(o) of more than 25% on the seventh day. The percent coefficient of variation of tacrolimus C(o) more than 22.5% before conversion is associated with higher risk of reduced C(o) after conversion (P<0.05). Compared with before conversion, less kidney transplant recipients have percent coefficient of variation more than 22.5% after conversion (3.1% vs. 17.4% with P<0.01). Conclusions. The results support that conversion from Prograf to Advagraf among kidney transplant recipient leads to a significantly lower C(o) and within-patient variability of tacrolimus C(o). The within-patient variability of C(o) before conversion influences C(o) on the sevent day after conversion to Advagraf

High Risk of Renal Failure in Stage 3B Chronic Kidney Disease is Under-recognized in Standard Medical Screening

Background: The objective of this study was to determine the risk of renal failure in patients with under-recognized chronic kidney disease (CKD) in the self-pay standard medical screening program of health management centers. Methods: The abbreviated Modification of Diet in Renal Disease equation was used to calculate the estimated glomerular filtration rate (eGFR) of study subjects. Study subjects with eGFR less than 60 mL/min/1.73 m(2) but with normal results of routine assessment, including serum creatinine, blood urea nitrogen, urinalysis and kidney ultrasound, were defined as having under-recognized CKD. Episodes of renal failure requiring dialysis within 2 years in subjects with stage 3 to stage 5 CKD were evaluated. Results: A total of 15,817 subjects were recruited and 28.4% of subjects were identified by routine assessments as having a kidney problem. The prevalences of CKD 3A, 3B, 4 and 5 were 8.3%, 1.9%, 0.3% and 0.2%, respectively. All subjects with stages 4 and 5 CKD had abnormal serum creatinine levels, but 48.7% of 1,507 subjects with stage 3 CKD (stage 3A, n=713; stage 3B, n=21) had normal routine assessments. Subjects with under-recognized stage 3B CKD had the highest risk (20%) of developing renal failure compared to subjects with stages 3-5 CKD and abnormal results of routine assessments. Conclusion: Identifying subjects with CKD stage 3 by the eGFR equation, especially in stage 3B, is advantageous in detecting the risk of renal failure over the routine clinical assessment that is currently carried out by health management institutions in Taiwan. [J Chin Med Assoc 2010;73(10):515-522

Imaging Evaluation of Kidney Using Multidetector Computerized Tomography in Living-Related Renal Transplantation

Background. Multidetector computerized tomography (MDCT) is lesser invasive than conventional angiography and has the advantage of assessment of vessels and surrounding anatomic variants before laparoscopic nephrectomy. Methods. From May 2005 to March 2011, 62 consecutive living kidney donors of mean age 45.3 +/- 12.7 years (range 24-70 y, male:female 26:36) underwent laparoscopic nephrectomy to paired recipients of mean age 44.8 +/- 14.0 years (range 17-74 y, male:female 38:24). The clinical characteristics and laboratory data of donors and recipients were collected for analysis. Graft function as indicated by estimated glomerular filtration rate (eGFR) was obtained from the last stable visit of the donors and the best value displayed by the recipients. Results. There was no significant correlation between CT kidney volume and and eGFR. By univariate analysis, donor age was associated with worse graft function (-0.51 mL/min lower eGFR per 1 year of donor age; P 45 y showed significantly lower eGFR. There was no effect of CT kidney volume <100 mL. Conclusions. Our preliminary data suggest that CT kidney volume does not predict posttransplantation graft function, but MDCT is still important for analysis of anatomy before laparoscopic nephrectomy among living donors