Serum amyloid P aids complement-mediated immunity to Streptococcus pneumoniae

The physiological functions of the acute phase protein serum amyloid P (SAP) component are not well defined, although they are likely to be important, as no natural state of SAP deficiency has been reported. We have investigated the role of SAP for innate immunity to the important human pathogen Streptococcus pneumoniae. Using flow cytometry assays, we show that SAP binds to S. pneumoniae, increases classical pathway–dependent deposition of complement on the bacteria, and improves the efficiency of phagocytosis. As a consequence, in mouse models of infection, mice genetically engineered to be SAP-deficient had an impaired early inflammatory response to S. pneumoniae pneumonia and were unable to control bacterial replication, leading to the rapid development of fatal infection. Complement deposition, phagocytosis, and control of S. pneumoniae pneumonia were all improved by complementation with human SAP. These results demonstrate a novel and physiologically significant role for SAP for complement-mediated immunity against an important bacterial pathogen, and provide further evidence for the importance of the classical complement pathway for innate immunity

Model and Design of a Power Driver for Piezoelectric Stack Actuators

A power driver has been developed to control piezoelectric stack actuators used in automotive application. A FEM model of the actuator has been implemented starting from experimental characterization of the stack and mechanical and piezoelectric parameters. Experimental results are reported to show a correct piezoelectric actuator driving method and the possibility to obtain a sensor-less positioning contro

Fretting wear of alloy steels at the blade tip of steam turbines

In order to reduce blade resonant vibration amplitude in turbomachinery, blades are assembled with a mutual interlocking at the tip. The aim of this study is to investigate the wear mechanism at the contact interface of the blade shroud in steam turbines. Experimental data are available concerning the wear mechanism at interfaces of aircraft engines blades, while the literature regarding the same effect on steam turbines is less rich. Moreover, the transposition of the results from the aero-engine to the steam turbine is difficult, because materials and working conditions are different. To overcome this lack of knowledge an experimental campaign was set up to investigate this wear mechanism under the specific conditions and with the distinctive materials used in steam turbines. Two base materials (alloy steels) were tested under different conditions: surface treatment (with and without laser quenching), temperature and normal load. Dissipated energies were determined from the hysteresis loops measured during the tests and were correlated to the test conditions. Profiles of worn surfaces were measured, and volume losses were accurately computed with a procedure that takes into account the roughness of the surfaces. Experiments were conducted both at room and low temperature (150 °C). At room temperature the surface temperature increased to 60-70 °C, due to the heat generated in the wear process. Comparison of volume losses at room and low temperature showed that at 150°C the volume losses decreased dramatically. This behavior was explained with a brittle-ductile transition. In other words, the same wear mechanism, adhesion and abrasion respectively in stick and gross slip condition, give very different results for a small softening effect of the material. Moreover, experimental results showed much more sensitive wear rates to the heat treatment than to the steel type

Experimental and numerical investigation of contact parameters in a dovetail type of blade root joints

This paper focuses on the contact characteristics of the blade root joints subjected to the dry friction damping under periodic excitation. The numerical method and experimental procedure are combined to trace the contact behavior in the nonlinear vibration conditions. In experimental procedure, a novel excitation method alongside the accurate measurements is used to determine the frequencies of the blade under different axial loads. In numerical simulations, local behavior of contact areas is investigated using the reduction method as a reliable and fast solver. Subsequently, by using both experimental measurements and numerical outcomes in a developed code, the global stiffness matrix is calculated. This leads to find the normal and tangential stiffness in the contact areas of a dovetail blade root joints. The results indicate that the proposed method can provide an accurate quantitative assessment for investigation the dynamic response of the joints with focusing the contact areas

Unbalanced Langmuir kinetics affects TASEP dynamical transitions: mean-field theory

In a previous study we developed a mean-field theory of dynamical transitions for the totally-asymmetric simple-exclusion process (TASEP) with open boundaries and Langmuir kinetics, in the so-called balanced regime, characterized by equal binding and unbinding rates. Here we show that simply including the possibility of unbalanced rates gives rise to an unexpectedly richer dynamical phase diagram. In particular, the current work predicts an unusual type of dynamical transition, which exhibits certain similarities with first-order phase transitions of equilibrium systems. We also point out that different types of dynamical transition are accompanied by different structural changes in the (mean-field) relaxation spectrum.Comment: 32 pages, 8 figure

Hysteresis-type electronic controlling device for fuel injectors and associated method

A hysteresis-type electronic controlling device is provided for fuel injectors that includes, but is not limited to a power driving unit for driving the fuel injectors with an electric signal, a control stage connected to the power driving unit and a sensing stage fed by the power driving unit and feeding the control stage, the device has a feedback frequency control stage for measuring a waveform period of the signal feeding the fuel injectors; the feedback frequency control stage is fed by the control stage with an electric signal. A fuel injector control method is also provided that includes, but is not limited to driving fuel injectors with an electric signal coming from a power driving unit fed by a control stage , sensing the signal with a sensing stage, and measuring a waveform period of the signal through the feedback frequency control stag

A C3(H20) recycling pathway is a component of the intracellular complement system

An intracellular complement system (ICS) has recently been described in immune and nonimmune human cells. This system can be activated in a convertase-independent manner from intracellular stores of the complement component C3. The source of these stores has not been rigorously investigated. In the present study, Western blotting identified a band corresponding to C3 in freshly isolated human peripheral blood cells that was absent in corresponding cell lines. One difference between native cells and cell lines was the time absent from a fluid-phase complement source; therefore, we hypothesized that loading C3 from plasma was a route of establishing intracellular C3 stores. We found that many types of human cells specifically internalized C3(H(2)O), the hydrolytic product of C3, and not native C3, from the extracellular milieu. Uptake was rapid, saturable, and sensitive to competition with unlabeled C3(H(2)O), indicating a specific mechanism of loading. Under steady-state conditions, approximately 80% of incorporated C3(H(2)O) was returned to the extracellular space. These studies identify an ICS recycling pathway for C3(H(2)O). The loaded C3(H(2)O) represents a source of C3a, and its uptake altered the cytokine profile of activated CD4(+) T cells. Importantly, these results indicate that the impact of soluble plasma factors should be considered when performing in vitro studies assessing cellular immune function

C1q acts in the tumour microenvironment as a cancer-promoting factor independently of complement activation

Complement C1q is the activator of the classical pathway. However, it is now recognized that C1q can exert functions unrelated to complement activation. Here we show that C1q, but not C4, is expressed in the stroma and vascular endothelium of several human malignant tumours. Compared with wild-type (WT) or C3- or C5-deficient mice, C1q-deficient (C1qa(-/-)) mice bearing a syngeneic B16 melanoma exhibit a slower tumour growth and prolonged survival. This effect is not attributable to differences in the tumour-infiltrating immune cells. Tumours developing in WT mice display early deposition of C1q, higher vascular density and an increase in the number of lung metastases compared with C1qa(-/-) mice. Bone marrow (BM) chimeras between C1qa(-/-) and WT mice identify non-BM-derived cells as the main local source of C1q that can promote cancer cell adhesion, migration and proliferation. Together these findings support a role for locally synthesized C1q in promoting tumour growth

Hysteresis-type electronic controlling device for fuel injectors and associated method

A hysteresis-type electronic controlling device is provided for fuel injectors that includes, but is not limited to a power driving unit for driving the fuel injectors with an electric signal, a control stage connected to the power driving unit and a sensing stage fed by the power driving unit and feeding the control stage, the device has a feedback frequency control stage for measuring a waveform period of the signal feeding the fuel injectors; the feedback frequency control stage is fed by the control stage with an electric signal. A fuel injector control method is also provided that includes, but is not limited to driving fuel injectors with an electric signal coming from a power driving unit fed by a control stage , sensing the signal with a sensing stage, and measuring a waveform period of the signal through the feedback frequency control stage