Self-assembled nanoparticle spirals from two-dimensional compositional banding in thin films

A self-assembly process is reported in which spiral patterns of goldnanoparticles form on siliconsurfaces during the epitaxial crystallization of thin gold-silicon alloy layers. This behavior is observed only for gold concentrations above a critical value and is shown to result from two-dimensional compositional banding of a liquid alloy layer during the crystallization process. The compositional banding consists of alternate gold-rich and silicon-rich alloy bands, which are shown to be a direct consequence of free energy minimization, the band spacing being that which gives the maximum diffusive composition-separation rate. Goldnanoparticles subsequently form by Ostwald ripening on the surface of the gold-rich bands to give rise to the observed spiral patterns.We thank P. Evans and D. Button for MEVVA implantation at Australian Nuclear Science Technology Organization under an AINSE Grant No. AINGRA05155P. We thank S.K. Bhargava at RMIT University for the financial support to D.K.V. to carry out initial stages of this research

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

Characterization of sputtered SmCo thin films for light element contamination using RBS and HIERDA techniques

Samarium cobalt films were prepared on silicon substrates with and without a chromium buffer layer at room temperature and 600°C using direct current unbalanced magnetron sputtering. For obtaining ideal magnetic properties, the films should be free from impurities, such as O, Al and others. Rutherford backscattering spectrometry and heavy ion elastic recoil detection analysis were used to determine the composition and film thickness and to monitor the light element contamination across film thickness. X-ray diffractometer and superconducting quantum interference device were employed to characterize the structure and magnetic properties of the films, respectively. The results obtained led to an improved design of the ground shield and the use of a sorption pump to effectively minimize aluminium and oxygen concentration in the films, respectively

Effect of argon gas pressure and substrate temperature on magnetic properties of magnetron sputtered SmCo thin films

No abstract available

A classic case of tuberous sclerosis with multisystem involvement including giant bilateral renal angiomyolipomas presenting as massive hematuria

BACKGROUND: Tuberous Sclerosis (TSC) also known as Bourneville disease is a neurocutaneous syndrome having an autosomal dominant inheritance pattern, though the condition has a high rate of spontaneous mutation. It is the second most common neurocutaneous syndrome after neurofibromatosis. This disease demonstrates a widespread potential for hamartomatous growths in multiple organ systems. CASE REPORT: We report a case of a 36-year-old female with TSC presenting as massive hematuria with underlying giant bilateral renal angiomyolipomas (AML) with estimated total tumor burden of more than 8 kg which is to the best of our knowledge the highest ever reported. The patient also had lymphangioleiomyomatosis and lesions in the brain, skin, teeth and bones. CONCLUSIONS: TSC has a wide variety of clinical and radiologic manifestations. It should be suspected when some of the common radiological manifestations are found, including CNS involvement, renal and hepatic AMLs and LAM, even if clinical signs are not obvious. Renal AMLs in setting of TSC may reach giant proportions and may present with massive hematuria

Patterning of magnetron sputtered SmCo thin films by excimer laser ablation

This paper presents the results of our investigations on excimer laser micromachining of SmCo thin films. These films were prepared onto silicon substrate with a SiO2 layer and chromium film on the top. The ablation characteristics of the films were analysed by examining the surface topography using optical microscopy and Scanning Electron Spectroscopy (SEM). The quality of the etched patterns was evaluated in terms of sharpness of the edges, side wall profile and ratio of pattern mask size to feature size. The etch characteristics were studied over a wide range of laser parameters with the fluence in the range 0.25 J/cm2 and 1.6 J/cm2 and the number of shots varied from 1 to 50. The results showed that the precise nature of the resulting structure is a strong function of fluence and number of shots. These studies provide insight into the ablation behaviour of SmCo films and their potential applications in MEMS

Total leukocyte count-based predictor tool for calculating hematopoietic progenitor cell dose in bone-marrow harvest

Background: Hematopoietic progenitor cell transplantation is increasingly being used as the curative therapy in India for various clinical conditions. There are three main sources of hematopoietic progenitor cells; hematopoietic progenitor cell-apheresis (HPC-A), hematopoietic progenitor cell-bone marrow (HPC-M) and hematopoietic progenitor cell-Umbilical Cord (HPC-C). The number of CD34+ cells in HPC-C is fixed. In HPC-A, the number of CD34+ cells collected is based on the baseline peripheral blood counts and a second harvest can be easily performed. The trickiest calculation of CD34+ cells adequacy is in case of HPC-M harvest, where the end point of harvest cannot be predetermined. Aim: The aim was to study the accuracy of a total leukocyte count (TLC)-based predictor tool in predicting CD34+ dose in comparison to the actual CD34+ cell counts in the harvest. Materials and Methods: This was a prospective study to validate the tool. The data captured included patient and donor demographic data, disease condition, mobilization regimen of the donor, progenitor cell harvest data, dose collected, cryopreservation if any, progenitor cell infusion data, engraftment, and follow-up of the patient including day thirty and day hundred chimerism in a tertiary care hospital. Results: Five patients were included in the study. For each patient, the target dose and volume were collected in a single HPC-M harvest attempt, and no repeat harvests were required. The average volume of HPC-M harvest collected was 195 ml. The average CD-34+ cell dose in HPC-M harvest achieved was 4.3 × 106/kg (Range = 3.39–6.42). This was 85.7% of the targeted dose calculated on the basis of TLC-based predictor tool. Conclusion: This study reiterates the importance of a simple TLC-based predictor tool (formula) for estimation of HPC-M volume to be harvested