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Data on COVID-19 vaccine acceptability among parents of children with multisystem inflammatory syndrome (MIS-C) are limited. In this cohort of children with MIS-C, enrolled in the Swissped RECOVERY trial (NCT 04826588), comparing intravenous immunoglobulins or methylprednisolone, who, in accordance with Swiss guidelines, were recommended for SARS-CoV-2 vaccination, 65% (73/112) of parents reported being vaccinated against SARS-CoV-2 before the MIS-C, while 70% were vaccinated after the MIS-C episode of their child. None of the children were vaccinated before the occurrence of the MIS-C, and only 9% (5/56) received the COVID-19 vaccine after the MIS-C. The predominant barriers to COVID-19 vaccination were concerns over potential side effects and insufficient support from their doctors. This emphasizes the crucial role of health care providers in promoting COVID-19 vaccination among children.

The emergence of paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS) led to the widespread use of anti-inflammatory treatments in the absence of evidence from randomised controlled trials (RCTs). We aimed to assess the effectiveness of intravenous methylprednisolone compared with intravenous immunoglobulins.

Introduction: Assessing bowel viability can be challenging during acute surgical procedures, especially regarding mesenteric ischaemia. Intraoperative fluorescence angiography (FA) may be a valuable tool for the surgeon to determine whether bowel resection is necessary and to define the most appropriate resection margins. The aim of this study is to report on FA use in the acute setting and to judge its impact on intraoperative decision making. Materials and methods: This is a multi-centre, retrospective case series of patients undergoing emergency abdominal surgery between February 2016 and 2021 in three general/colorectal units where intraoperative FA was performed to assess bowel viability. Primary endpoint was change of management after the FA assessment. Results: A total of 93 patients (50 males, 66.6 ± 19.2 years, ASA score ≥ III in 85%) were identified and studied. Initial surgical approach was laparotomy in 66 (71%) patients and laparoscopy in 27 (29% and seven, 26% conversions). The most common aetiologies were mesenteric ischaemia (n= 42, 45%) and adhesional/herniae-related strangulation (n= 41, 44%). In 50 patients a bowel resection was performed. Overall rates of anastomosis after resection, reoperation and 30-day mortality were 48% (n= 24/50, one leak), 12% and 18%, respectively. FA changed management in 27 (29%) patients. In four patients (4% overall), resection was avoided and in 21 (23%) extra bowel length was preserved (median 50 cm of bowel saved, IQR 28–98) although three patients developed further ischaemia. FA prompted extended resection (median of 20 cm, IQR 10–50 extra bowel) in six (6%) patients. Conclusion: Intraoperative use of FA impacts surgical decisions regarding bowel resection for intestinal ischaemia, potentially enabling bowel preservation in approximately one out of four patients. Prospective studies are needed to optimize the best use of this technology for this indication and to determine standards for the interpretation of FA images and the potential subsequent need for second-look surgeries.

In a world of increased mobility and globalized business, many families face increasing complexity in the area of currency risk management. This article describes the sources of currency risks for [...]

Refractory cardiogenic and vasoplegic shock after congenital heart surgery is a threatening condition leading to high morbidity and mortality. Control of hemodynamic and inflammatory response is fundamental in medical strategy. We report the case of a newborn with cardiogenic and vasoplegic shock secondary to cardiopulmonary bypass for atrioseptostomy and prostaglandin treatment in the context of hypoplastic left heart syndrome, successfully treated with a combination of mechanical circulatory support and cytokine hemoadsorption column (CytoSorb®). Vasopressor support was weaned during the time of treatment without multiple organ failure occurrence. The use of CytoSorb®cartridge inserted in an extra-corporeal circuit even in a newborn is easy and feasible, as long as some precautions are considered. Routine monitoring of drugs levels is mandatory during the use of the cartridge and immediately after.

Panton-Valentine leucocidin producing methicillin-resistant Staphylococcus aureusinfections are rare but associated with very high mortality rates. We report the case of a 14-year-old patient with Panton-Valentine leucocidin producing methicillin-resistant Staphylococcus aureusinfection and Influenza B pneumonia requiring veno-arterial extra-corporeal membrane oxygenator for refractory shock. In the absence of response to conventional therapy, we have inserted a Cytosorb® cartridge within the extra-corporeal membrane oxygenator circuit. A spectacular decrease in vasopressor requirements followed. Since clindamycin, a key component of Panton-Valentine leucocidin producing methicillin-resistant Staphylococcus aureustreatment, might be removed by Cytosorb® hemoadsorption, we have performed serial plasma concentrations measurements of the drug. Based on these measurements, we were able to develop a pharmacokinetic model incorporating variable plasma clearance. Patient’s exposure was estimated before, during and after Cytosorb® hemoadsorption. According to this model, Cytosorb® hemoadsorption did not seem to result in significant clindamycin removal. Cytosorb® hemoadsorption during Panton-Valentine leucocidin producing methicillin-resistant Staphylococcus aureusinfection appears safe and feasible and no adaptation of clindamycin dosage seems necessary

French TGV high-speed train technology 14 is currently making rapid inroads into northern Europe, particularly in Belgium and the Netherlands. The line linking Rotterdam and Amsterdam crosses a stretch about [...]

Congenital cardiac malformations with high pulmonary blood flow and pressure due to left‐to‐right shunts are usually repaired in early infancy for both the benefits of early relief of heart failure and the fear that the concomitant pulmonary hypertension may become irreversible unless these defects are corrected at an early age. Age, however, has been a poor predictor of irreversibility of pulmonary hypertension in our experience, which is presented here. A retrospective observational study. We defined “late” as age ≥2 years. We examined clinical, echocardiographic, and hemodynamic data from all patients aged ≥2 years with such malformations referred to us from 2004 untill 2015. Department of Pediatric Cardiology and Cardiac Surgery, University Hospital of Vaud, Lausanne, Switzerland. There were 39 patients, aged 2–35 years (median: 5 years), without chromosomal abnormalities. All had malformations amenable to biventricular repair, and all had high systolic right ventricular pressures by echocardiography prior to referral. All patients underwent catheterization for assessment of pulmonary hypertension. If this was reversible, surgical correction was offered. (1) Operability based on reversibility of pulmonary hypertension. (2) When surgery was offered, mortality and evidence of persisting postoperative pulmonary hypertension were examined. Eighteen patients had no pulmonary hypertension, 5 of variable ages were inoperable due to irreversible pulmonary hypertension, and 16 had reversible pulmonary hypertension. Therefore, 34 patients underwent corrective surgery, with no immediate or late mortality. Pulmonary arterial and right ventricular pressures decreased noticeably in all operated patients. This is sustained to date; they are all asymptomatic with no echocardiographic evidence of pulmonary hypertension at a median follow‐up of 7 years (range 2–13 years). Pulmonary hypertension may still be reversible in many surprisingly old patients with left‐to‐right shunt lesions, who may therefore still be operable.

An important aspect of perioperative care in pediatric cardiac surgery is maintenance of optimal hemodynamic status using vasoactive/inotropic agents. Conventionally, this has focused on maintenance of cardiac output rather than perfusion pressure. However, this approach has been abandoned in our center in favor of one focusing primarily on perfusion pressure, which is presented here and compared to the conventional approach. A retrospective study. Regional center for congenital heart disease. University Hospital of Lausanne, Switzerland. All patients with Aristotle risk score ≥8 that underwent surgery from 1996 to 2012 were included. Patients operated between 1996 and 2005 (Group 1: 206 patients) were treated according to the conventional approach. Patients operated between 2006 and 2012 (Group 2: 217 patients) were treated according to our new approach. All patients had undergone surgery for correction or palliation of congenital cardiac defects. Mortality, duration of ventilation and inotropic treatment, use of ECMO, and complications of poor peripheral perfusion (need for hemofiltration, laparotomy for enterocolitis, amputation). The two groups were similar in age and complexity. Mortality was lower in group 2 (7.3% in group 1 vs 1.4% in group 2, P< .005). Ventilation times (hours) and number of days on inotropic/vasoactive treatment (all agents), expressed as median and interquartile range [Q1–Q3] were shorter in group 2: 69 [24–163] hours in group 1 vs 35 [22–120] hours in group 2 (P< .01) for ventilation, and 9 [3–5] days in group 1 vs 7 [2–5] days in group 2 (P< .05) for inotropic/vasoactive agents. There were no differences in ECMO usage or complications of peripheral perfusion. Results in pediatric cardiac surgery may be improved by shifting the primary focus of perioperative care from cardiac output to perfusion pressure.

Given the current severe shortage of available livers for transplantation, there is an urgent need to maximize the utilization of donor organs. One of the strategies to increase the number of available livers for transplantation is to improve organ utilization through the use of elderly, overweight, or organs donated after circulatory death (DCD). However, the utilization of these “marginal” organs was associated with an increased risk of early allograft dysfunction, primary non-function, ischemic biliary complications or even re-transplantation. Ischemia–reperfusion (IR) injury is a key mechanism in the pathogenesis of these complication. Although conventional static cold preservation provides some protection against IR injury, more-advanced preservation methods are needed to improve outcomes after transplantation of marginal livers or obtained after circulatory death. Among the most promising strategies is the utilization of ex-vivo machine perfusion. Recently, a variety of perfusion machines have received approval for clinical use, each differing in terms of perfusion temperature and oxygenation capabilities. Overall, clinical trials have demonstrated that these devices have resulted in superior posttransplant outcomes and increased utilization of marginal livers, leading to their widespread adoption. In this review, we aim to provide both the rationale and up-to-date clinical evidence for machine perfusion, along with its potential future applications.

Growth of thin Si films deposited on the 5-fold symmetry surface of the icosahedral Al-Pd-Mn quasicrystal is monitored by low-energy electron diffraction, secondary-electron imaging, and Auger electron spectroscopy. We observe that below a sample temperature of 370 K, Si grows in an amorphous structure. Above 370 K, a new Al-Pd-Mn-Si quasicrystalline phase, which exhibits the same icosahedral symmetry as the substrate, is formed at the surface by substitutionally replacing Al by absorbed Si.

ABSTRACTThe adipose organ, which comprises brown, white and beige adipocytes, possesses remarkable plasticity in response to feeding and cold exposure. The development of beige adipocytes in white adipose tissue (WAT), a process called browning, represents a promising route to treat metabolic disorders. While surgical procedures constantly traumatize adipose tissue, its impact on adipocyte phenotype remains to be established. Herein, we studied the effect of trauma on adipocyte phenotype one day after sham, incision control, or surgical injury to the left inguinal adipose compartment. Caloric restriction was used to control for surgery-associated body temperature changes and weight loss. We characterized the trauma-induced cellular and molecular changes in subcutaneous, visceral, interscapular, and perivascular adipose tissue using histology, immunohistochemistry, gene expression, and flow cytometry analysis. After one day, surgical trauma stimulated adipose tissue browning at the site of injury and, importantly, in the contralateral inguinal depot. Browning was not present after incision only, and was largely independent of surgery-associated body temperature and weight loss. Adipose trauma rapidly recruited monocytes to the injured site and promoted alternatively activated macrophages. Conversely, PDGF receptor-positive beige progenitors were reduced. In this study, we identify adipose trauma as an unexpected driver of selected local and remote adipose tissue browning, holding important implications for the biologic response to surgical injury.

Recent symptoms stand as a major determinant of stroke risk in patients with carotid stenosis, likely reflective of atherosclerotic plaque destabilization. In view of emerging links between vascular and adipose biology, we hypothesized that human perivascular adipose characteristics associate with carotid disease symptom status.

Dietary protein restriction (PR) has rapid effects on metabolism including improved glucose and lipid homeostasis, via multiple mechanisms. Here, we investigate responses of fecal microbiome, hepatic transcriptome, and hepatic metabolome to six diets with protein from 18% to 0% of energy in mice. PR alters fecal microbial composition, but metabolic effects are not transferable via fecal transplantation. Hepatic transcriptome and metabolome are significantly altered in diets with lower than 10% energy from protein. Changes upon PR correlate with calorie restriction but with a larger magnitude and specific changes in amino acid (AA) metabolism. PR increases steady-state aspartate, serine, and glutamate and decreases glucose and gluconeogenic intermediates. 13C6 glucose and glycerol tracing reveal increased fractional enrichment in aspartate, serine, and glutamate. Changes remain intact in hepatic ATF4 knockout mice. Together, this demonstrates an ATF4-independent shift in gluconeogenic substrate utilization toward specific AAs, with compensation from glycerol to promote a protein-sparing response.

Children with cyanotic congenital heart diseases have a higher risk of bleeding or thrombosis. Rotational thromboelastometry, using tissue factor (EXTEM), a contact activator (INTEM), or cytochalasin (FIBTEM), assesses coagulation by determining the time to initiation of clotting (CT) and clot firmness (MCF), including platelet-fibrin-interaction. This study aimed to evaluate rotational thromboelastometry and whole blood impedance aggregometry in cyanotic congenital heart diseases (CCHD) compared with a control group without chronic cyanosis (NCHD) in a pediatric cohort. We prospectively included 200 patients (60 CCHD, 140 NCHD). Oxygen saturation in CCHD was 76% [70–85], and 98% [97−100] in NCHD (p < 0.00001). Hemoglobin and hematocrit were significantly higher in CCHD; platelet count was significantly lower in the same group. Platelet aggregation was under normal range in 77% of CCHD after triggering with thrombin-receptor activating protein. Rotational thromboelastometry showed significantly longer clotting times and reduced clot firmness in both EXTEM and INTEM tests. FIBTEM clot firmness was also significantly reduced. In children with CCHD, a moderate inverse correlation was found between platelet count and hematocrit, with a stronger correlation after one year of age (r = - 0.58, p < 0.00001). Significant correlations were found between hematocrit, rotational thromboelastometry parameters, and impedance aggregometry parameters, so as for platelet count—the strongest correlation in CCHD after one year of age. In conclusion, according to rotational thromboelastometry and impedance aggregometry, children with CCHD present relevant hypocoagulable disorders related to cyanosis duration, but no data demonstrate hypercoagulability.

A new robust fixed-order RST controller design approach by convex optimization is proposed in this paper. Only frequency-domain data are considered in the approach for linear time-invariant single-input single-output systems. It is shown that performance specifications given as the infinity norm of the weighted sensitivity functions can be represented as convex constraints in the Nyquist diagram. One of the advantage of the proposed method is that it can deal directly with multi-model uncertainty. Moreover, a solution to a real industrial problem is given showing the effectiveness of the method.

This paper describes interactive applications used to illustrate an advanced course on multivariable contrssol. The direct manipulation of features in graphics, such as eigenvectors in the phase plane or observer eigenvalues in the complex plane, gives the student the means to explore not only the effect of parameters in the ranges usually considered as realistic, but also to observe the consequences of more extreme choices and get a better understanding of the design methods. The applications are implemented in Sysquake to provide a simple user interface, consistent across a wide range of examples from classical to advanced control.

Convex parameterization of fixed-order robust stabilizing controllers for systems with polytopic uncertainty is represented as a linear matrix inequality (LMI) using the Kalman-Yakubovich-Popov (KYP) lemma. This parameterization is a convex inner approximation of the whole nonconvex set of stabilizing controllers, and depends on the choice of a central polynomial. It is shown that, with an appropriate choice of the central polynomial, the set of all stabilizing fixed-order controllers that place the closed-loop poles of a polytopic system in a disk centered on the real axis can be outbounded with some LMIs. These LMIs can be used for robust pole placement of polytopic systems. [ABSTRACT FROM AUTHOR]

This paper presents an overview of our recent work on a model-free proportional−integral−derivative (PID) controller tuning procedure. The method can handle different stability and performance indicators in the frequency domain. The phase margin, gain margin, crossover frequency, and more-advanced indicators, which are the infinity-norm of the sensitivity functions, can be considered for the design. The actual values of the design parameters are measured directly on the system, thanks to closed-loop experiments. A frequency criterion is then defined as the weighted sum of squared errors between the measured and desired values of the design parameters. The minimization is done iteratively using the Gauss−Newton algorithm. The approach presented does not require any parametric model of the plant and can be applied to a wide range of industrial applications. Simulation examples show the rapid convergence of the algorithm and the effectiveness of the method for PID controller tuning.

Growth of thin Si films deposited on the 5-fold symmetry surface of the icosahedral Al-Pd-Mn quasicrystal is monitored by low-energy electron diffraction, secondary-electron imaging, and Auger electron spectroscopy. We observe that below a sample temperature of 370?K, Si grows in an amorphous structure. Above 370?K, a new Al-Pd-Mn-Si quasicrystalline phase, which exhibits the same icosahedral symmetry as the substrate, is formed at the surface by substitutionally replacing Al by absorbed Si.

In diesem Aufsatz wird der gegenwärtige Stand der Biokatalyse in der chemischen Industrie beschrieben. Obwohl uns die Vorteile chemischer Methoden bekannt sind, gehen wir davon aus, dass der Einsatz biologischer Katalyseverfahren durch die jüngsten Fortschritte bei der künstlichen Evolution von Genen, die für Enzyme codieren, drastisch zunehmen wird. Erstmals ist es möglich, die schnelle Entwicklung eines Enzyms für eine spezifische chemische Reaktion zu verfolgen. Durch diese Technik kann das Enzym an die Bedingungen des Verfahrens angepasst werden. Wir beschreiben hier die Entwicklung einer Technologie für die künstliche Evolution von Enzymen und speziell das zugrunde liegende DNA-Shuffling. Dabei gehen wir auf verschiedene Enzymklassen, ihre gegenwärtigen Einsatzmöglichkeiten und die Einschränkungen, die überwunden werden sollten, ein. In einem Aufsatz dieses Umfangs ist es unmöglich, auf alle Enzyme mit einem Potential für eine industrielle Nutzung einzugehen; es gibt weitere Enzymklassen, die bei entsprechender Aktivität, Selektivität und Stabilität nützlich für Industriechemiker werden können. Die Biokatalyse befindet sich in einer aufregenden Ära, und wir erwarten große Fortschritte in der nahen Zukunft.

This review describes the current state of biocatalysis in the chemical industry. Although we recognize the advantages of chemical approaches, we suggest that the use of biological catalysis is about to expand dramatically because of the recent developments in the artificial evolution of genes that code for enzymes. For the first time it is possible to consider the rapid development of an enzyme that is designed for a specific chemical reaction. This technology offers the opportunity to adapt the enzyme to the needs of the process. We describe herein the development of enzyme evolution technology and particularly DNA shuffling. We also consider several classes of enzymes, their current applications, and the limitations that should be addressed. In a review of this length it is impossible to describe all the enzymes with potential for industrial exploitation; there are other classes, which given appropriate activity, selectivity, and robustness, could become useful tools for the industrial chemist. This is an exciting era for biocatalysis and we expect great progress in the future.

The occurrence of a thermally induced first-order transition affecting the amidolytic activity of plasmin adsorbed onto bare and protein-modified graphite and glassy carbon was demonstrated in the 10–45°C temperature range in the presence of a chromogenic substrate. Modification of the surfaces was achieved upon spontaneous adsorption of plasmin to surfaces bearing a coating of fibrinogen, whether electrochemically oxidized or not. The amount of fibrinogen adsorbed at graphite was determined by ELISA. The kinetics of the transition was characterized by its starting temperature (Tc), which was between 14 and 19°C, the first-order rate constant, and the activation energy Eadeduced from Arrhenius plots. Results showed the absence of a correlation between Tc, Ea, and contact angle variations. It is therefore likely that these variables address separate steps in a complex pathway of reactions undergone by plasmin under mild thermal constraints.

Western blotting methods have been used to assess the specificity of polyclonal antibodies raised against Bacillus globigiispore and vegetative cell preparations. None of the antibodies studied were completely species‐specific in their recognition of spore surface epitopes. One polyclonal serum recognized several spore surface epitopes and demonstrated limited cross‐reaction with the spore surface of the near‐neighbour species B. subtilis. A second polyclonal serum, raised against aged spore antigens, recognized damaged spore epitopes primarily. Both of these antibodies also cross‐reacted with vegetative cell epitopes present in all four Bacillusspecies (B. globigii, B. subtilis, B. cereus and B. anthracis) studied.

Designing a controller usually involves several iterations between the synthesis based on a set of parameters, the analysis of the robustness and performance obtained so far, and correction of the design parameters. An approach based on Computer-Aided Design is proposed, where the engineer manipulates the graphics with a mouse, sees immediately how the performance changes, and feels how the different objectives are linked. The instantaneous performance display enables understanding the problem better and obtaining a satisfactory compromise. Applications to research and education are described.

A cement rotary kiln is a nonlinear, multivarible, distrubted paramete system. Since a model describing the whole heating process iS not available, separate control Schemes are designed for the preheater process and kiln process. The fuel consumption minimization is achieved by determining appropriate heating set points. To reach desired production rate, we connected the two above mentioned controllers. we present experimental results using an industrial cement kiln and show that our approach resulted in excellent performance.

Automatic control is often taught simultaneously to students of various engineering disciplines. Since the course contents have to be accessible to all students, a highly interdisciplinary approach to the material is needed.

A new General Bounding Theorem for the number of extrema that may occur in the step-response of a stable linear discrete system is presented. The theorem is applicable to stable systems with real zeros and real poles. Upper and lower bounds on the number of extrema are easily computed from knowledge of the pole-zero configuration of the discrete transfer function. The lower bound reflects the fact that zeros in the region of convergence always cause extrema. A new result is that zeros of type M3, defined as those located between the fastest and the slowest poles, can also produce extrema which always appear in a waver pattern consisting of a pair of consecutive extrema. Sufficient conditions for extrema free response are established. The results are verified using a numerical example. It is shown that waver peaks can lead to overshoot. Based on simulation studies and analytical arguments, it is argued that waver extrema is more likely to be realized when M3zeros located are closer to the dominant pole

Many control specifications are simultaneously taken into account in a multiobjective approach where structured uncertainty is characterized by multiple models. Both frequency- and time-domain specifications are included for all models. A gradient-based optimization, in the weighted least-squares framework, is proposed. The worst cases are emphasized in order to enforce all the specifications to be satisfied. A benchmark example is used for illustration.

This paper presents the study of a servomechanism problem where the output of a nonlinear plant must follow a reference value. A suboptimal adaptive control procedure is developed and applied to the practical case of a continuous stirred tank reactor; it is shown that the results compare favourably with those obtained by use of classical or optimal techniques.

Tracking controllers arc usually based on the principle that the reference signal is known beforehand. Thus all time delays of the process can be simply eliminated by feeding the desired reference to the controller in advance. In this paper, it is proposed to introduce the desired reference an extra time in advance. This can be done in a way so as to change the transients while leaving the steady state response unaffected. As opposed to other preview-based approaches, the simplicity of the proposed design is emphasized. Moreover, the obtained results can outperform those based on optimality considerations. It is also shown that the tracking error as well as the actuator effort can be reduced during the transients.

In this paper we derive a reduced model, that is a model in terms of independent generalized coordinates, for the equations of motion of constrained rigid bodies including closed-chain mechanisms. We characterize the domain of validity of the model in which the constrained mechanisin’ satisfies the constraints and is not in a singular configuration. We use our results to derive the equations of motion of a planar version of the Delta parallel robot.

A complete kinematics and inverse dynamics model in closed form of the Delta Parallel Robot is devel- opped. The modelling approach uses only inverse kinematics and Newton laws to obtain an inverse dynamics model called “in the two spaces” since it is parametrized by the robot’s state in both task space and joint space.The proposed modelling process can be applied to all fully parallel robot structures and it is shown that the number of computations required to evaluate the model is not larger than the standard case of a serial robot.

This paper presents an integrated solution to develop fast real-time applications in an academic environment. The solution is based on a framework which guides the user through all the necessary steps: from the selection of a control solution to its real-time implementation and validation. With the proposed framework, students can concentrate on the control concepts. The difficult implementation aspects, such as the real-time programming and the hardware interfacing, are completely managed by the framework and transparent for the user. The framework user interface is well adapted to meet didactic requirements, and its ease of use leads to a reduced learning period.

The information on the mechanism is in general available through the joint coordinates. Full control of the mechanism requires that the position and orientation of each solid be derivable from this information. Formally, this derivation amounts to solving a system of algebraic equations. The latter admits in general more than one solution, each corresponding to a different mechanism assembly mode. The control problem is thus to choose the right solution, i.e., the one corresponding to the mechanism posture. It is however vain to hope that a blindly launched numerical (yet converging) algorithm will end up in a correct posture. In this paper an algorithm converging globally to the right solution is proposed. This Kantorovitch theorem based algorithm is of a polynomial complexity, and is valid for an arbitrary mechanism. Its efficiency is tested on a reputed difficult example of a generalized Gough-Stewart platform.

We report the catalytic properties of plasmin irreversibly adsorbed to surfaces made of a mixture of graphite carbon with nujol (graphite carbon paste). The assay of the immobilized enzyme was achieved, under forced convection, with a specific and chromogenic substrate (S-2251) dissolved in the solution, under varying temperatures and pH conditions. Results showed that these two variables affected more critically the activity of the adsorbed enzyme than that of the free form. Also differences observed in the respective activity vs pH relationships suggested that the coated surface was able to discriminate between different isoelectric forms of plasmin. Time-varying activities observed in the temperature range 10-30°C were interpretated in terms of the first-ordered thermal denaturation reaction, which affected some of the adsorbed plasmin forms.

Sliding control is known to have excellent robustness properties against parametric uncertainty and non-linearities. However, if parameter changes are bigger than some limits, the sliding mode is destroyed and a bad transient behaviour is obtained.

A parameter-adaptive controller for fast processes is discussed in this paper. Its application to a hydraulic machine tool axis is presented. This nonlinear system is identified on-line with a reduced order model using a recursive least squares algorithm. The controller is based on self-tuning pole placement with feedforward control. An original supervision algorithm is designed to generate an on/off signal for the identification and to control the update of the controller parameters. The algorithms are implemented on a TMS32010 signal processor.

In this paper, an approach is proposed that allows to identify all the parameters of the friction model described by Canudas de Wit et al. (1995). Model properties are used to identify a reduced number of parameters in the convenient context of linear dynamic systems. In fact, two experiments, steady-state characteristics and analysis of system dynamics in the presliding regime, are sufficient to identify all parameters of the model. Experimental data are presented for the industrial application of an axis used for electro-discharge machining (EDM).