Homogenity Study of Bauxite Reference Materials

Laboratories involved in chemical analysis are becoming more aware of the need to implement some kind of quality system. In order to ensure that correct level of accuracy is achieved, it is imperative that quality policies must be based on use of Certified Reference materials.Homogen-eity and stability are two crucial characteristics of any Certified Reference materials (CRM). Utmost care must be taken during preparation of materials as homogeneous and stable possible. However, careful preparation by itself is not enough. Positive demonstration of homogeneity is essential from the perspective of implementing uncertainty calculation. In many cases, homogeneity studies fail to give sufficient quantitative information, mainly because of a lack of measurement repeatability and insufficient number of replicates. In this work a systematic approach has been followed for preparation of Bauxite Certified Reference Materials

Thin layer chromatographic study of Indian bauxites

65-73Thin layer chromatography (TLC) has been used for the detection and separation of Al³⁺, Fe²⁺, Si⁴⁺ and Ti⁴⁺ in bauxite. Thirty bauxite samples of different geological origin have been studied to identify the optimized chromatographic systems capable of selective separations of the constituents. Binary and ternary separations of Al³⁺, Fe²⁺, Ti⁴⁺ and Si⁴⁺ in bauxite were realized with chromatographic systems comprising various combinations of silica gel G, silica gel H and microcrystalline cellulose coated plates and aqueous mobile phases consisting alkali salt solutions, formic acid and hydrochloric acid etc. The chromatographic system consisting of silica gel H and mixture of 10% aqueous solutions of sodium chloride and formic acid in 8:2 (v/v) ratio was found to be the ideal combination for the analogous separation of Al³⁺, Fe²⁺ and Ti⁴⁺ in bauxites. The efficacy of optimized chromatographic system has been investigated by monitoring reproducibility of RF values and spot compactness with respect to change in bauxite geology, sample concentration and change of mobile phase composition. Chromatograms of the cations were quantitatively evaluated by scanning densitometry in comparison with wet analysis method

Single-cell expression profiling reveals dynamic flux of cardiac stromal, vascular and immune cells in health and injury

Besides cardiomyocytes (CM), the heart contains numerous interstitial cell types which play key roles in heart repair, regeneration and disease, including fibroblast, vascular and immune cells. However, a comprehensive understanding of this interactive cell community is lacking. We performed single-cell RNA-sequencing of the total non-CM fraction and enriched (Pdgfra-GFP+) fibroblast lineage cells from murine hearts at days 3 and 7 post-sham or myocardial infarction (MI) surgery. Clustering of >30,000 single cells identified >30 populations representing nine cell lineages, including a previously undescribed fibroblast lineage trajectory present in both sham and MI hearts leading to a uniquely activated cell state defined in part by a strong anti-WNT transcriptome signature. We also uncovered novel myofibroblast subtypes expressing either pro- fibrotic or anti-fibrotic signatures. Our data highlight non-linear dynamics in myeloid and fibroblast lineages after cardiac injury, and provide an entry point for deeper analysis of cardiac homeostasis, inflammation, fibrosis, repair and regeneration