Deviations Induced by Tool Sharpening in the Profile of Three Screw Pump Rotors

Three screw pumps represent an important family of positive displacement rotary pumps. They are quite easy to construct, even if the use of a shaped milling cutter for the rotor machining can cause some problems when the tool is not new. In fact the sharpening of the tool modifies the total geometry of the milling cutter by reducing its diameter. The shape of the single cutter does not change, but the cutter radial position is shifted towards the tool center. This causes deviations in the profile cut and the screws consequently need a long breaking in. In this paper the problem is analyzed from a quantitative point of view, using a method that allows us to determine the machining error as a function of the tool geometry variation. Moreover some alternative solutions to this problem are suggested

Non Undercutting Conditions in Internal Gears

Many contributions regarding internal gear theory exist in literature. They mainly consider the problem of undercutting by means of analytical methods applied to specific and limited cases. The present paper deals with a general method showing the analytical condition for avoiding undercutting by the use of the concept of the limit curve. In particular the analytical determination of the limit curve allows the designer to obtain significant graphical representations of the design limits

Analytical Model of a Particular Type of Positive Displacement Blower

Many papers exist in literature which deal with the twin screw compressor; this usually has two different rotors, a male and a female, and is commonly used to produce compressed gas for industrial uses. However, a different type of positive displacement rotary compressor with two screws is sometimes used; one of its typical applications is in car engine supercharging. Present paper deals with the latter type, which is defined as a two screw blower. This blower has two identical helical rotors, each with three lobes. The kinematics and the geometry of the rotors are analysed here, and a complete mathematical model for the rotor is defined. Moreover different possible shapes of the rotors, depending on the design parameters, are analysed and the limitations in the choice of the design parameters are presented. Finally an analysis of the theoretical specific slipping of the rotors is presented, showing which zones of the profile are the most stressed. This model will be useful for further studies on rotor pressure loads and blower dynamics

Pre-shaping motion input for a rotating flexible link

The interest in the design of manipulators for space operations with a light structure has grown meaningfully in comparison with rigid manipulators, even if these flexible manipulators are unavoidably characterized by a not negligible structural flexibility. This paper deals with the first phase of a project financed by a grant from the Italian Space Agency (ASI) which is concerned with the setting up of an open loop control for a planar manipulator with flexible linkages. In this phase, the project is subdivided into two parts: on one hand, different command inputs have been proposed for point to point operations; on the other hand, dynamic simulations have been carried out by using a multibody model with flexible parts, in order to evaluate the residual vibrations due to the selected command input at the end of the motion. These command inputs will be applied to the actual manipulator, which is already available, in a future phase of the project. The command inputs, which are described here, are based on both the convolution of special impulse inputs suitably chosen on the basis of the system natural frequencies and the reduction of impulsive inertia forces by means of a suitable algorithm proposed here and derived from cam design. The simulations are carried out by commercial software for the study of multibody systems and custom programs for the command input implementation. The results obtained for the residual vibrations are compared to those obtained by conventional command inputs in the simulations on the same model

Biomechanical analysis of pedalling for rehabilition purposes: experimental results on two pathological subjects and comparison with non-pathological findings

In this paper the experimental results obtained by means of a prototype measuring device dedicated to the evaluation of the rehabilitation level of the lower limb are presented. The analysis of the experimental data collected on non-pathological subjects allows the identification of the characteristic meaning of the most significant parameters typical of healthy subjects. These data have been employed for a systematic comparison with the same parameters measured on two pathological subjects, in order to define quantitative indicators of the rehabilitation degree of the lower limbs and indicators of the “quality” of the movement

Altered Metabolic Profile in Congenital Lung Lesions Revealed by1H Nuclear Magnetic Resonance Spectroscopy

Congenital lung lesions are highly complex with respect to pathogenesis and treatment. Large-scale analytical methods, like metabolomics, are now available to identify biomarkers of pathological phenotypes and to facilitate clinical management. Nuclear magnetic resonance (NMR) is a unique tool for translational research, as in vitro results can be potentially translated into in vivo magnetic resonance protocols. Three surgical biopsies, from congenital lung malformations, were analyzed in comparison with one control sample. Extracted hydrophilic metabolites were submitted to high resolution 1H NMR spectroscopy and the relative concentration of 12 metabolites was estimated. In addition, two-dimensional NMR measurements were performed to complement the results obtained from standard monodimensional experiments. This is one of the first reports of in vitro metabolic profiling of congenital lung malformation. Preliminary data on a small set of samples highlights some altered metabolic ratios, dealing with the glucose conversion to lactate, to the relative concentration of phosphatidylcholine precursors, and to the presence of myoinositol. Interestingly some relations between congenital lung lesions and cancer metabolic alterations are found

Calcium Binds to Transthyretin with Low Affinity

The plasma protein transthyretin (TTR), a transporter for thyroid hormones and retinol in plasma and cerebrospinal fluid, is responsible for the second most common type of systemic (ATTR) amyloidosis either in its wild type form or as a result of destabilizing genetic mutations that increase its aggregation propensity. The association between free calcium ions (Ca2+) and TTR is still debated, although recent work seems to suggest that calcium induces structural destabilization of TTR and promotes its aggregation at non-physiological low pH in vitro. We apply high-resolution NMR spectroscopy to investigate calcium binding to TTR showing the formation of labile interactions, which leave the native structure of TTR substantially unaltered. The effect of calcium binding on TTR-enhanced aggregation is also assessed at physiological pH through the mechano-enzymatic mechanism. Our results indicate that, even if the binding is weak, about 7% of TTR is likely to be Ca2+-bound in vivo and therefore more aggregation prone as we have shown that this interaction is able to increase the protein susceptibility to the proteolytic cleavage that leads to aggregation at physiological pH. These events, even if involving a minority of circulating TTR, may be relevant for ATTR, a pathology that takes several decades to develop

Metabolomic profile of amniotic fluid to evaluate lung maturity: the diaphragmatic hernia lamb model

Background: Tracheal occlusion (TO) stimulates lung growth in fetuses affected with congenital diaphragmatic hernia (CDH) although the processes involved in lung maturation still remain unknown. The objective of this study was to evaluate the metabolomic profile of amniotic fluid (AF) following TO in fetal lamb model in order to obtain an indirect view of mechanisms involved in pulmonary reversal hypoplasia and biochemical maturity in response to fetal TO. Methods: Liquid Chromatography Mass Spectrometry was performed on lamb AF samples at: age I (70 days' gestation); age II (102 days' gestation); age III (136 days' gestation). CDH was induced at age I and TO at age II. Results: Betaine, choline, creatinine were found significantly increased during gestation in the control group. The CDH group showed choline (p =0.007) and creatinine (p =0.004) decreases during pregnancy. In the TO group choline and creatinine profiles were restored. Conclusions: Alveolar tissue and fetal global growth ameliorated after TO. Metabolomics provided usefu information on biochemical details during lung maturation. Metabolomic profiling would help to identify the best time to perform TO, in order to increase survival of CDH affected patients

IBtkα Activates the β‐Catenin‐Dependent Transcription of MYC through Ubiquitylation and Proteasomal Degradation of GSK3βin Cancerous B Cells

The IBTK gene encodes the IBtkα protein that is a substrate receptor of E3 ubiquitin ligase, Cullin 3. We have previously reported the pro‐tumorigenic activity of Ibtk in MYC‐dependent B‐ lymphomagenesis observed in Eμ‐myc transgenic mice. Here, we provide mechanistic evidence of the functional interplay between IBtkα and MYC. We show that IBtkα, albeit indirectly, activates the β‐catenin‐dependent transcription of the MYC gene. Of course, IBtkαassociates with GSK3β and promotes its ubiquitylation, which is associated with proteasomal degradation. This event increases the protein level of β‐catenin, a substrate of GSK3β, and results in the transcriptional activation of the MYC and CCND1 target genes of β‐catenin, which are involved in the control of cell division and apoptosis. In particular, we found that in Burkitt’s lymphoma cells, IBtkα silencing triggered the downregulation of both MYC mRNA and protein expression, as well as a strong decrease of cell survival, mainly through the induction of apoptotic events, as assessed by using flow cytometry‐based cell cycle and apoptosis analysis. Collectively, our results shed further light on the complex puzzle of IBtkα interactome and highlight IBtkα as a potential novel therapeutic target to be employed in the strategy for personalized therapy of B cell lymphoma

The expression of inhibitor of bruton's tyrosine kinase gene is progressively up regulated in the clinical course of chronic lymphocytic leukaemia conferring resistance to apoptosis.

Chronic lymphocytic leukaemia (CLL) is the most common B-cell malignancy with a variable clinical outcome. Biomarkers of CLL progression are required for optimising prognosis and therapy. The Inhibitor of Bruton's tyrosine kinase-isoform α (IBTKα) gene encodes a substrate receptor of Cullin 3-dependent E3 ubiquitin ligase, and promotes cell survival in response to the reticulum stress. Searching for novel markers of CLL progression, we analysed the expression of IBTKα in the peripheral blood B-cells of CLL patients, before and after first line therapy causing remission. The expression of IBTKα was significantly increased in disease progression, and decreased in remission after chemotherapy. Consistently with a pro-survival action, RNA interference of IBTKα increased the spontaneous and Fludarabine-induced apoptosis of MEC-1 CLL cells, and impaired the cell cycle of DeFew B-lymphoma cells by promoting the arrest in G0/G1 phase and apoptosis. Consistently, RNA interference of IBTKα up regulated the expression of pro-apoptotic genes, including TNF, CRADD, CASP7, BNIP3 and BIRC3. Our results indicate that IBTKα is a novel marker of CLL progression promoting cell growth and resistance to apoptosis. In this view, IBTKα may represent an attractive cancer drug target for counteracting the therapy-resistance of tumour cells