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A common problem in motion control is the onset of vibrations due to the inertial forces when a compliant load is being displaced. It is the case of the vibration of large machine tools, but also the vibration of slender loads in pick&place. The main goal of the present work is to predict and minimise the overshoot that a compliant load moved by a servodrive suffers when it reaches the final position. Instead of modifying the control algorithm or adding dampers, the authors propose an optimal path planning based on the selection of a square sine velocity profile, a standard in machine tools NCs. Thus, a 3 degrees of freedom mechatronic model that integrates the dynamics of the drive-transmission-compliant load system and the control has been developed to predict the overshoot. Analysing the velocity profile, it has been possible to determine several values of the commanded jerk that minimize the overshoot and are related to the natural frequency of the compliant load. The prediction of the overshoot magnitude as well as the optimal jerk values have been experimentally validated in a workbench with a single axis with a ball screw transmission and a compliant load where a laser interferometer has been used to measure the overshoot.

Parallel continuum mechanisms are closed, kinematic, chained compliant mechanisms that are mobile due to flexible and slender elements. Large deformations and the force-moment equilibrium require a more complex modeling of the kinematic analysis than in their rigid-link counterparts. Although real-time solutions to the position problem using numerical iterative methods are available, a comprehensive kinematic analysis of such mechanisms has not yet been conducted. The first step to this end is a procedure that solves the full forward and inverse kinematic problems, and is proposed in this paper for planar systems to allow for an easier interpretation of their kinematic characteristics. This procedure provides the means to obtain multiple solutions arising from the closed-loop structure and the multiplicity of the buckling mode of slender links.

It is important for the mechatronic design of robotic systems to rely on accurate models. To that end, system identification methods are a convenient tool to obtain the values of the unknown dynamic parameters which play a key role. In this paper, it is investigated the application of the principle of energy equivalence to easily obtain a suitable model for identification of the inertial parameters and friction of planar mechanisms. The methodology here proposed is then applied to the prototype RePlaLink, a 5R haptic mechanism. Experimental data was obtained to carry out the identification, and the results were then validated by using a different trajectory than the one used for the identification of the unknown parameters. It was found that the identified model developed for the mechanism using the herein described methodology, was able to predict the dynamic behavior of the mechanism.

Summary: Some patients with cancer never develop metastasis, and their host response might provide cues for innovative treatment strategies. We previously reported an association between autoantibodies against complement factor H (CFH) and early-stage lung cancer. CFH prevents complement-mediated cytotoxicity (CDC) by inhibiting formation of cell-lytic membrane attack complexes on self-surfaces. In an effort to translate these findings into a biologic therapy for cancer, we isolated and expressed DNA sequences encoding high-affinity human CFH antibodies directly from single, sorted B cells obtained from patients with the antibody. The co-crystal structure of a CFH antibody-target complex shows a conformational change in the target relative to the native structure. This recombinant CFH antibody causes complement activation and release of anaphylatoxins, promotes CDC of tumor cell lines, and inhibits tumor growth in vivo. The isolation of anti-tumor antibodies derived from single human B cells represents an alternative paradigm in antibody drug discovery. : Bushey et al. clone antibodies against complement factor H (CFH) from single human B cells. CFH protects tumor cells from complement-dependent cytotoxicity (CDC). The authors demonstrate that a recombinant CFH antibody induces CDC of tumor cells, inhibits tumor growth in vivo, and stimulates infiltration of the tumor by lymphocytes.

Productivity and surface finish are typical user manufacturer requirements that are restrained by chatter vibrations sooner or later in every machining operation. Thus, manufacturers are interested in knowing, before building the machine, the dynamic behaviour of each machine structure with respect to another. Stability lobe graphs are the most reliable approach to analyse the dynamic performance. During heavy rough turning operations a model containing (a) several modes, or (b) modes with non-conventional (Cartesian) orientations is necessary. This work proposes two methods which are combined with multimode analysis to predict chatter in big horizontal lathes. First, a traditional single frequency model (SFM) is used. Secondly, the modern collocation method based on the Chebyshev polynomials (CCM) is alternatively studied. The models can be used to identify the machine design features limiting lathe productivity, as well as the threshold values for choosing good cutting parameters. The results have been compared with experimental tests in a horizontal turning centre. Besides the model and approach, this work offers real worthy values for big lathes, difficult to be got from literature. Basque Country Government, GAITEK program.

The stability of a thin wall workpiece milling process is investigated through a single degree of freedom system that mimics the milling machine operation. The stability lobes were computed by using the Enhanced Multistage Homotopy Perturbation Method (EMHPM), the Chebyshev Collocation, the Semi-Discretization and Full-Discretization methods. A comparison of these methods with respect to experimental data and computational time was made to identify the method with the best performance in terms of accuracy and computational time in order to optimize the material removal rate by using the Simulated Annealing algorithm (SA). Then, we have used the EMHPM with the SA algorithm to establish the optimal cutting conditions. Based on numerical simulation computed by combining the SA algorithm with the EMHPM and experimental data, we have determined the optimum cutting condition in less than 400 ms which is 100 times faster than the off-line methods used to find the stability lobes.

Aeronautics is a business in a continuous growing sector and aircraft manufacturing is without any doubt a high-priced process. Each part of the aircraft and particularly engine parts represent the most expensive elements due to the difficulty of manufacturing their complex geometry. In this case, the test piece to carry out the study has been the Blisk. The predicted lead time for one of these components is so long that any progress related to the manufacturing process implies a considerable amount of saving. Due to the critical nature of the parts common defects such as chatter marks, smearings or pickups originated during the manufacturing process that will reduce the part life are not allowed. In this article, considering the existing demand of better manufacturing technologies a study case based on an Inconel 718 Blisk finishing operations study is developed. A static model for machining forces prediction is developed to finally validate it with the real machining forces measured during the machining process.

This work deals with the characterization of a three stage multivariable tool used for high-performance milling and the modelling of its dynamic behaviour to predict the stability against chatter. The influence of the variable pitch, variable helix and variable rake angle on each cutting edge of the tool is modeled to calculate the stability lobes diagrams. The proposed approach includes a mechanistic milling forces model and a cutting coefficients characterization procedure along with a modification of the Enhanced Multistage Homotopy Perturbation Method (EMHPM) to capture the multivariable phenomena of the tool in stability prediction, resulting in an accurate method to reproduce the regenerative vibration problem in end milling. Experimental data is provided to validate the followed approach for this new tool concept.

Chatter vibrations produced during turning of slender parts or boring with flexible tools lead to a wavy work surface, and reduce the spindle headstock life span as well. This study deals with the problem of chatter prediction in straight turning of non-rigid parts, making use of round inserts. A stability model for straight turning has been developed using the Chebyshev collocation method for the first. This algorithm allows the introduction of an accurate round insert edge geometry, discretising the lead position angle and the variable cutting coefficients of the forces model along the edge. The method is applied to a SDOF system by means of a specially designed testpart and demonstrates its usefulness to determine chatter-free conditions.

This paper provides an integrated approach for designing large milling machines, taking both mass reduction of mobile structural components and the maximum material removal rate into account. This approach considers a representative milling operation and a productivity target as a starting point, and then deals with the design of the machine to achieve the targeted productivity with structural components of minimum mass. The procedure is based on modeling the interactions between process and machine by means of a stability model of the milling process in modal coordinates. The model allows the identification of the mechanical design parameters that limit the productivity as well as the threshold values that must be met to ensure the targeted productivity. Those values are reached in an iterative procedure that minimizes the mass of the critical structural components of the machine. This approach has been applied to the re-design of an actual milling machine, on which, once built and adjusted, the machining tests conducted have shown increases above 100% in productivity, consuming at the same time 13% less energy due to mass reduction above 20% in mobile structural components. In this way, an eco-efficient milling machine that performs highly productive machining processes has been designed and built.

γ-Al 2 O 3 modified supports with bimodal pore-size distributions were prepared by the addition of different types of natural sepiolites (α or β) into alumina. The supports were characterized by nitrogen physisorption, mercury porosimetry, X-ray diffraction, HRTEM and DTA techniques. A wide range of S BET (94–238 m 2 g − 1 ), pore volumes (0.3–0.82 cm 3 g − 1 ), and pore sizes were obtained in the supports depending on the type of sepiolite and its concentration added into alumina. The pore sizes were distributed as follows: mesopores around 1.8 nm in radius, mesopores in the radius range 3.0–25 nm and macropores between 25 and 300 nm in radius. The shape of the pore-size distributions depended on the type of sepiolite: the modal peak for pores larger than 3.0 nm was broad with β-type sepiolites and narrow with α-type sepiolites. The mesopore and macropore sizes can be controlled by the type of sepiolite as well as its concentration added to alumina.

This paper presents a model for the prediction of surface topography in peripheral milling operations taking into account that the tool vibrates during the cutting process. The model includes the effect of tool vibrations in the equations of the cutting edge paths, which are transformed into equivalent polynomial equations and solved for discrete positions along the feed direction by applying a standard root finder. Through this procedure, surface topography generation is simplified with respect to other models in literature. The model allows the topography, the roughness values and the form errors of the milled surface to be predicted. Cutting test results show good agreement with model predictions.

This paper presents a model for the topography prediction of ball-end milled surfaces, considering the tool parallel axis offset. First, the equations of cutting edge trajectories and the envelope equation of the material swept by the tool are derived. Later, the trajectories are cut by planes perpendicular to the feed direction obtaining a set of transcendental equations that are solved by transforming them to polynomial equations through Chebyshev expansions. This procedure presents the advantage on previous models in literature of not requiring any starting point to achieve the solution. Finally, experimental results are presented and compared to the model predictions.

In this paper, a three-dimensional dynamic model for the calculation of the stability lobes of low rigidity parts is applied for the prediction of chatter vibrations during the finish milling of aeronautical parts that include thin walls and thin floors. Hence, an accurate selection of both axial depth of cut and spindle speed can be done. The following methodology is applied: first, a modal analysis of the test device is performed; second, stability lobes are calculated; finally milling tests validate the approach. In the example included in this work, the lobes diagrams obtained for the thin floors are accurate, defining an approximate borderline of stability.

The structural properties of La 2 O 3 and Al 2 O 3 –La 2 O 3 binary oxides prepared by sol–gel were studied by XRD, HRTEM and UV–vis. The binary oxides with high lanthana contents show an amorphous structure after calcination at 650 °C. At calcination temperatures higher than 1000 °C there is a phase transformation from the amorphous state to the crystalline LaAlO 3 with a perovskite structure. The structure of La 2 O 3 is consistent with the hexagonal system; however, some crystalline microdomains with a monoclinic structure were detected by HRTEM. Islands of La 2 O 3 and LaAl 11 O 18 phases were detected at high lanthana concentration in the binary oxide. The modification in the coordination shell of the Al 3+ cations due to the interaction with La 3+ cations confirms the formation of phases with a perovskite structure and the presence of islands of the LaAl 11 O 18 phase.

High speed machining of low rigidity structures is a widely used process in the aeronautical industry. Along the machining of this type of structures, the so-called monolithic components, large quantities of material are removed using high removal rate conditions, with the risk of the instability of the process. Very thin walls will also be milled, with the possibility of lateral vibration of them in some cutting conditions and at some stages of machining. Chatter is an undesirable phenomenon in all machining processes, causing a reduction in productivity, low quality of the finished workpieces, and a reduction of the machine-spindle's working life. In this study, a method for obtaining the instability or stability lobes, applicable when both the machine structure and the machined workpiece have similar dynamic behaviours, is presented. Thus, a 3-dimensional lobe diagram has been developed based on the relative movement of both systems, to cover all the intermediate stages of the machining of the walls. This diagram is different and more exact than the one that arises out of the mere superposition of the machine and the workpiece lobe diagrams. A previous step of rejecting resonance modes that are not involved in the milling at the bottom zones of the thin walls must be previously performed. Finally, the proposed method has been validated, by machining a series of thin walls, applying cutting conditions contrasted with the limits previously obtained in the three-dimensional lobe diagram.

A tritiated form of the non-peptide delta-opioid receptor agonist (+)-BW373U86 ((+)-4-((alpha-R)-alpha-((2S,5R)-4-allyl-2, 5-dimethyl-l-piperazinyl)-3-hydroxybenzyl)-N,N-diethylbenzamide) was synthesized and its binding characteristics studied. [3H](+)-BW373U86 bound with subnanomolar affinity to rat brain membranes and was displaced most effectively by ligands selective for delta-opioid receptors. Naltrindole, naltriben, and 7-benzylidenenaltrexone exhibited apparent inhibition constants of 0.06, 1.54, and 4.49 nM, respectively, while mu- or kappa-selective ligands showed little affinity for this site. [3H](+)-BW373U86 binding was sensitive to the presence of guanine nucleotides; GDP caused a 3-fold decrease and 5'-guanylyl-imidodiphosphate (Gpp[NH]p) caused a 25% increase in binding affinity.

Single crystals of Mn 3 B 7 O 13 Br (MnBr) boracite were studied between 300 and 550 K by means of thermal, dielectric, pyroelectric and ferroelectric characterization, under simultaneous visual control of the ferroelectric/ferroelastic domain state of the samples. We observe an unusual change of sign of the pyroelectric coefficient in MnBr at about 440 K which can be an indication of the existence of a new phase transition in this compound. A preliminary DSC study seems to confirm the presence of such a transition.

A cDNA clone (Krev-1) has recently been identified that possesses the ability to reverse the transformed phenotype when introduced into a K-ras-transformed NIH 3 T 3 cell line. The Krev-1 protein, also known as rap-1A, was found to share 50% homology with the ras proteins. The rap-1A protein has also been shown to block the interaction of ras with its GTPase activating protein in vitro, leading to speculation regarding its role in vivo. A closely related protein, rap-1B, has also been identified in platelets, human erythroleukemia cells, neutrophils, and aortic smooth muscle cells. Unlike rap-1A, rap-1B has been shown to be phosphorylated in platelets. Given the high degree of similarity between the amino acid sequences of rap-1A and rap-1B, we sought to investigate the effect of microinjected rap-1B on H-ras(Val12)-induced germinal vesicle breakdown in Xenopus laevis oocytes. In this assay system, equimolar concentrations of rap-1B were found to block germinal vesicle breakdown triggered by the oncogenic ras protein. However, in the presence of IGF-1, this inhibition was not observed. Moreover, rap-1B is readily phosphorylated in the oocyte.

In this report, we demonstrate the expression of the mammalian System A neutral amino acid transporter in Xenopus laevis oocytes following microinjection of mRNA from rat liver, Chinese hamster ovary (CHO) cells, and human placenta. Stage 6 oocytes were injected with poly(A+) mRNA from one of these three sources and incubated for 24 h prior to assaying Na(+)-dependent 2-aminoisobutyric acid transport to monitor the increase in System A activity. The endogenous 2-aminoisobutyric acid uptake rates in oocytes were sufficiently slow so as to provide a low background value that was subtracted to obtain transport rates for the mammalian carrier alone. The degree of expression of the mammalian System A activity in Xenopus oocytes corresponded to the known transport rates in the tissue from which the mRNA was prepared. For example, hepatic mRNA from glucagon-treated rats produced greater System A activity than mRNA from control animals, and the mRNA from the CHO transport mutant cell line alar4-H3.9, which overproduces System A, resulted in higher transport rates than mRNA from the parental cell line (CHO-K1). Fractionation of total mRNA poly(A+) by nondenaturing agarose gel electrophoresis revealed transport activity associated with a 2.0-2.5-kilobase mRNA fraction common to each of the three tissues tested.