A New Colorimetric Assay for Methionyl Aminopeptidases: Examination of the Binding of a New Class of Pseudopeptide Analog Inhibitors

A direct and convenient spectrophotometric assay has been developed for methionine aminopeptidases (MetAPs). The method employs the hydrolysis of a substrate that is a methionyl analogue of p-nitroaniline (l-Met-p-NA), which releases the chromogenic product p-nitroaniline. This chromogenic product can be monitored continuously using a UV–Vis spectrophotometer set at 405 nm. The assay was tested with the type I MetAP from Escherichia coli (EcMetAP-I) and the type II MetAP from Pyrococcus furiosus (PfMetAP-II). Using l-Met-p-NA, the kinetic constants kcat and Km were determined for EcMetAP-I and PfMetAP-II and were compared with those obtained with a “standard” high-performance liquid chromatography (HPLC) discontinuous assay. The assay has also been used to determine the temperature dependence of the kinetic constant kcat for PfMetAP-II as well as to screen two novel pseudopeptide inhibitors of MetAPs. The results demonstrate that l-Met-p-NA provides a fast, convenient, and effective substrate for both type I and type II MetAPs and that this substrate can be used to quickly screen inhibitors of MetAPs

Maxima and Octave in Development of Online Applications: Service Based Approach

The paper shows a way for fast development of interactive online applications that can be used in teaching process. It introduces the web service implemented in PHP programming language for two free computer algebra systems Maxima and Octave. It can be later used for building web applications that need to solve some mathematical tasks during their running. The example of such implementation is also shown

Nuclear charge radii of light isotopes based on frequency comb measurements

Optical frequency comb technology has been used in this work for the first time to investigate the nuclear structure of light radioactive isotopes. Therefore, three laser systems were stabilized with different techniques to accurately known optical frequencies and used in two specialized experiments. Absolute transition frequency measurements of lithium and beryllium isotopes were performed with accuracy on the order of 10^(−10). Such a high accuracy is required for the light elements since the nuclear volume effect has only a 10^(−9) contribution to the total transition frequency. For beryllium, the isotope shift was determined with an accuracy that is sufficient to extract information about the proton distribution inside the nucleus. A Doppler-free two-photon spectroscopy on the stable lithium isotopes (6,7)^Li was performed in order to determine the absolute frequency of the 2S → 3S transition. The achieved relative accuracy of 2×10^(−10) is improved by one order of magnitude compared to previous measurements. The results provide an opportunity to determine the nuclear charge radius of the stable and short-lived isotopes in a pure optical way but this requires an improvement of the theoretical calculations by two orders of magnitude. The second experiment presented here was performed at ISOLDE/CERN, where the absolute transition frequencies of the D1 and D2 lines in beryllium ions for the isotopes (7,9,10,11)^Be were measured with an accuracy of about 1 MHz. Therefore, an advanced collinear laser spectroscopy technique involving two counter-propagating frequency-stabilized laser beams with a known absolute frequency was developed. The extracted isotope shifts were combined with recent accurate mass shift calculations and the root-mean square nuclear charge radii of (7,10)^Be and the one-neutron halo nucleus 11^Be were determined. Obtained charge radii are decreasing from 7^Be to 10^Be and increasing again for 11^Be. While the monotone decrease can be explained by a nucleon clustering inside the nucleus, the pronounced increase between 10^Be and 11^Be can be interpreted as a combination of two contributions: the center-of-mass motion of the 10^Be core and a change of intrinsic structure of the core. To disentangle these two contributions, the results from nuclear reaction measurements were used and indicate that the center-of-mass motion is the dominant effect. Additionally, the splitting isotope shift, i.e. the difference in the isotope shifts between the D1 and D2 fine structure transitions, was determined. This shows a good consistency with the theoretical calculations and provides a valuable check of the beryllium experiment

Continuous dialysis of citric acid: Solubility and diffusivity in Neosepta-AMH membrane

The transport of citric acid through an anion-exchange membrane Neosepta-AMH in a two-compartment continuous dialyzer has been investigated. The basic data obtained were completed by the measurement of the sorption isotherm. Mass transfer rate has been quantified by diffusivity of citric acid in the membrane, which has been determined from the acid concentrations in the streams entering and leaving the dialyzer. For that purpose, a set of ordinary differential equations describing the concentrations profiles in both the compartments of the dialyzer has been numerically solved in the connection with an optimizing procedure. In the mathematical model used, mass transfer resistances in liquid films on both sides of the membrane have been taken into account. All the experiments carried out at steady state (temperature 25 °C) revealed that first diffusivity of citric acid in the Neosepta-AMH membrane gradually increases with an increasing acid concentration until reaching a weak maximum at an acid concentration of c = 0.464 kmol m–3, then it slightly decreases. In the concentration range of citric acid in the membrane from 0 to 0.558 kmol m–3, diffusivity of acid was in the limits from 1.79 ×10–12 to 3.33 ×10–12 m2 s–1

Continuous dialysis of citric acid: Solubility and diffusivity in Neosepta-AMH membrane

The transport of citric acid through an anion-exchange membrane Neosepta-AMH in a two-compartment continuous dialyzer has been investigated. The basic data obtained were completed by the measurement of the sorption isotherm. Mass transfer rate has been quantified by diffusivity of citric acid in the membrane, which has been determined from the acid concentrations in the streams entering and leaving the dialyzer. For that purpose, a set of ordinary differential equations describing the concentrations profiles in both the compartments of the dialyzer has been numerically solved in the connection with an optimizing procedure. In the mathematical model used, mass transfer resistances in liquid films on both sides of the membrane have been taken into account. All the experiments carried out at steady state (temperature 25 °C) revealed that first diffusivity of citric acid in the Neosepta-AMH membrane gradually increases with an increasing acid concentration until reaching a weak maximum at an acid concentration of c = 0.464 kmol m–3, then it slightly decreases. In the concentration range of citric acid in the membrane from 0 to 0.558 kmol m–3, diffusivity of acid was in the limits from 1.79 ×10–12 to 3.33 ×10–12 m2 s–1

Cryopreservation of Human Gametes and Embryos: Current State and Future Perspectives

Cryopreservation of human gametes and embryos is an important and widely used method in most embryology laboratories. During last years, the practice of single embryo transfer was a greater demand for reliable cryostorage of surplus embryos. Currently, there are two basic principally different methods usable for cryopreservation: slow freezing and vitrification. Vitrification is a very promising method with massive use in embryology. Nowadays, this method is also suitable for cryopreservation of human mature oocytes (one of the most problematic cell in cryobiology). This progress in the field of cryopreservation opens new perspectives in assisted reproduction. Recent effective oocyte vitrification systems have a significant impact on clinical practice. This chapter gives a view of human gametes (sperms, oocytes) and embryos cryopreservation application and possibilities. Indications and methods of cryopreservation and thawing are mentioned

A first course in feedback, dynamics and control: findings from an online pilot survey for the IFAC community

Undergraduate students in many engineering programs around the world take only one control course. The IFAC Educational Committee has developed and piloted to a limited audience a comprehensive survey for the topics to be included in such course. This issue is relevant to both academia and industry. The paper discusses the initial findings related to the design of the survey as well as the responses of the participants. The findings will be used to refine the survey and distribute it in the near future to the global control community

Cloud e-learning for mechatronics: CLEM

his paper describes results of the CLEM project, Cloud E-learning for Mechatronics. CLEM is an example of a domain-specific cloud that is especially tuned to the needs of VET (Vocational, Education and Training) teachers. An interesting development has been the creation of remote laboratories in the cloud. Learners can access such laboratories to support their practical learning of mechatronics without the need to set up laboratories at their own institutions. The cloud infrastructure enables multiple laboratories to come together virtually to create an ecosystem for educators and learners. From such a system, educators can pick and mix materials to create suitable courses for their students and the learners can experience different types of devices and laboratories through the cloud. The paper provides an overview of this new cloud-based e-learning approach and presents the results. The paper explains how the use of cloud computing has enabled the development of a new method, showing how a holistic e-learning experience can be obtained through use of static, dynamic and interactive material together with facilities for collaboration and innovation