Development of New PM Iron-Based Materials for Self-Lubricating Bearings

Using PM technologies, new antifriction materials based on iron powder with different addition elements were developed in order to obtain self-lubricated bearings with improved tribological features. The elemental powder mixtures were blended for 2 hours in a 3D homogenization device, were compacted at a pressure of 500 MPa, and then sintered in dry hydrogen atmosphere at different temperatures for different maintaining times. The effect of technological parameters on physical properties (density and dimensional changes) was presented in this study. The mechanical and tribological properties (tensile strength, hardness, impact energy, friction coefficient, and wear rate) related to addition elements were evaluated. The tribological behaviour of the selected iron-based alloys was analysed by pin on disc tests without lubrication. Also, the wear surface scars and the microstructure of the wear surfaces were investigated

Isolation and functional analysis of cellular components of the bronchiolar stem cell hierarchy

Mouse bronchiolar stem cells have been identified in vivo based on functional characteristics including naphthalene resistance, long-term retention of labeled DNA precursors, and dual expression of markers for airway (CCSP) and alveolar (pro-SPC) epithelium. Further characterization would benefit from establishment of rigorous enrichment strategies allowing analysis of their behavior in vitro and following transplantation, and the establishment of a defining gene expression signature. We have determined that Epithelial Cell Adhesion Molecule (EpCAM) and Integrin α6 are expressed on the cell surface of both alveolar and bronchiolar epithelial cells and that low levels of Sca-1 expression characterize the bronchiolar epithelium. Within the Sca-1low EpCAMpos Integrinα6pos population of bronchiolar epithelial cells, autofluorescence (AF) levels distinguish the facultative transit-amplifying population which is AFhi from bronchiolar stem cells which are AFlow. Use of transgenic animal models allowing expansion or depletion of the stem cell compartment and use of lineage tracing strategies have allowed us to determine the identity of cells isolated based on their cell surface phenotype and autofluorescence characteristics. Injury models associated with depletion of terminally differentiated ciliated cells (ozone) or facultative transit amplifying population (naphthalene) were used to validate the functional characteristics of the two fractions of bronchiolar progenitors. In conclusion, we have developed and validated a fractionation approach for the generation of highly purified preparations of bronchiolar stem and Clara cells from the mouse lung. These data enable establishment of robust in vitro and transplantation assays to further validate the functional behavior of stem and facultative TA (Clara) cells and allows analysis of gene expression profile of the two populations towards a better understanding of unique characteristics of the bronchiolar stem cell compartment

A Cellular Pathway Involved in Clara Cell to Alveolar Type II Cell Differentiation after Severe Lung Injury

Regeneration of alveolar epithelia following severe pulmonary damage is critical for lung function. We and others have previously shown that Scgb1a1-expressing cells, most likely Clara cells, can give rise to newly generated alveolar type 2 cells (AT2s) in response to severe lung damage induced by either influenza virus infection or bleomycin treatment. In this study, we have investigated cellular pathway underlying the Clara cell to AT2 differentiation. We show that the initial intermediates are bronchiolar epithelial cells that exhibit Clara cell morphology and express Clara cell marker, Scgb1a1, as well as the AT2 cell marker, pro-surfactant protein C (pro-SPC). These cells, referred to as pro-SPC[superscript +] bronchiolar epithelial cells (or SBECs), gradually lose Scgb1a1 expression and give rise to pro-SPC[superscript +] cells in the ring structures in the damaged parenchyma, which appear to differentiate into AT2s via a process sharing some features with that observed during alveolar epithelial development in the embryonic lung. These findings suggest that SBECs are intermediates of Clara cell to AT2 differentiation during the repair of alveolar epithelia following severe pulmonary injury.Singapore-MIT Alliance for Research and Technology Center. Infectious Disease Research Grou

The Foaming Window – A New Concept and Mechanism for Biocomposite Foams Processing by Two-Step Sintering

 The two steps sintering process provide economical, technological and innovative advantageous aspects to produce biocomposite foams for alloplastic bone grafts applications. The kinetic window mechanism, working during the 2nd TSS step, provides the nanostructured ceramic matrix, respectively improved biocompatibility. Simultaneously, the high porous structure, fitting the trabecular bone tissue, remained an important technical request of such applications up to this research. The porous biocomposite scaffold could be designed using specific foaming agents, like titanium hydride, calcium carbonate and ammonium bicarbonate, by controlling the foaming reactions depending on the foaming agents’ type and content into the chemical composition of the initial biocomposite powder mixture. The new concept of foaming window, working during the 1st TSS step, includes these factors able to provide the specific foam structure fitting the required biocomposite foams porosity. Both windows may work for the benefit of the nanostructured highly porous biocomposite manufacturing by TSS process, in advantageous technical and economical terms

The Foaming Window – A New Concept and Mechanism for Biocomposite Foams Processing by Two-Step Sintering

 The two steps sintering process provide economical, technological and innovative advantageous aspects to produce biocomposite foams for alloplastic bone grafts applications. The kinetic window mechanism, working during the 2nd TSS step, provides the nanostructured ceramic matrix, respectively improved biocompatibility. Simultaneously, the high porous structure, fitting the trabecular bone tissue, remained an important technical request of such applications up to this research. The porous biocomposite scaffold could be designed using specific foaming agents, like titanium hydride, calcium carbonate and ammonium bicarbonate, by controlling the foaming reactions depending on the foaming agents’ type and content into the chemical composition of the initial biocomposite powder mixture. The new concept of foaming window, working during the 1st TSS step, includes these factors able to provide the specific foam structure fitting the required biocomposite foams porosity. Both windows may work for the benefit of the nanostructured highly porous biocomposite manufacturing by TSS process, in advantageous technical and economical terms

Poster session: Problem definition for effective workload management

The paper introduces the problem of designing dynamic workload management (WM) tools that are aware of the diversity of classes of users and their diverse access patterns. Our approach should be contrasted with the current WM tools and their ability of detecting performance degradations in accordance with the user’s preference goals. We define the problem and suggest a formal definition that allows the further development of algorithms and architectures that allow the implementation of effective on-line database tuning strategies. 1

Airway Epithelial Progenitors Are Region Specific and Show Differential Responses to Bleomycin-Induced Lung Injury

Mechanisms that regulate regional epithelial cell diversity and pathologic remodeling in airways are poorly understood. We hypothesized that regional differences in cell composition and injury-related tissue remodeling result from the type and composition of local progenitors. We used surface markers and the spatial expression pattern of an SFTPC-GFP transgene to subset epithelial progenitors by airway region. Green fluorescent protein (GFP) expression ranged from undetectable to high in a proximal-to-distal gradient. GFP(hi) cells were subdivided by CD24 staining into alveolar (CD24(neg)) and conducting airway (CD24(low)) populations. This allowed for the segregation of three types of progenitors displaying distinct clonal behavior in vitro. GFP(neg) and GFP(low) progenitors both yielded lumen containing colonies but displayed transcriptomes reflective of pseudostratified and distal conducting airways, respectively. CD24(low)GFP(hi) progenitors were present in an overlapping distribution with GFP(low) progenitors in distal airways, yet expressed lower levels of Sox2 and expanded in culture to yield undifferentiated self-renewing progeny. Colony-forming ability was reduced for each progenitor cell type after in vivo bleomycin exposure, but only CD24(low)GFP(hi) progenitors showed robust expansion during tissue remodeling. These data reveal intrinsic differences in the properties of regional progenitors and suggest that their unique responses to tissue damage drive local tissue remodeling. Disclosure of potential conflicts of interest is found at the end of this article

Functional Analysis of Two Distinct Bronchiolar Progenitors during Lung Injury and Repair

Air spaces of the mammalian lung are lined by a specialized epithelium that is maintained by endogenous progenitor cells. Within bronchioles, the abundance and distribution of progenitor cells that contribute to epithelial homeostasis change as a function of maintenance versus repair. It is unclear whether functionally distinct progenitor pools or a single progenitor cell type maintain the epithelium and how the behavior is regulated in normal or disease states. To address these questions, we applied fractionation methods for the enrichment of distal airway progenitors. We show that bronchiolar progenitor cells can be subdivided into two functionally distinct populations that differ in their susceptibility to injury and contribution to repair. The proliferative capacity of these progenitors is confirmed in a novel in vitro assay. We show that both populations give rise to colonies with a similar dependence on stromal cell interactions and regulation by TGF-β. These findings provide additional insights into mechanisms of epithelial remodeling in the setting of chronic lung disease and offer hope that pharmacologic interventions may be developed to mitigate tissue remodeling

β-Catenin Is Not Necessary for Maintenance or Repair of the Bronchiolar Epithelium

Signaling by Wnt/β-catenin regulates self-renewal of tissue stem cells in the gut and, when activated in the embryonic bronchiolar epithelium, leads to stem cell expansion. We have used transgenic and cell type–specific knockout strategies to determine roles for β-catenin–regulated gene expression in normal maintenance and repair of the bronchiolar epithelium. Analysis of TOPGal transgene activity detected β-catenin signaling in the steady-state and repairing bronchiolar epithelium. However, the broad distribution and phenotype of signaling cells precluded establishment of a clear role for β-catenin in the normal or repairing state. Necessity of β-catenin signaling was tested through Cre-mediated deletion of Catnb exons 2–6 in airway epithelial cells. Functional knockout of β-catenin had no impact on expression of Clara cell differentiation markers, mitotic index, or sensitivity of these cells to the Clara cell–specific toxicant, naphthalene. Repair of the naphthalene-injured airway proceeded with establishment of focal regions of β-catenin–null epithelium. The size of regenerative epithelial units, mitotic index, and restoration of the ciliated cell population did not vary between wild-type and genetically modified mice. Thus, β-catenin was not necessary for maintenance or efficient repair of the bronchiolar epithelium