Microgrippers to handle Organoids and pancreatic Islets for Precision Measurements of biological Function

The model of the cultured single cell is considered insufficient to explain the physiological regulation taking place at the organ level. The same is true for the prediction of drug action at the organ level or at the level of the intact organism. For these reasons 3D cell culture models are in increasing demand. It is thus necessary to develop the instruments to handle such cell aggregates and organoids in a controlled, precise and gentle manner. Here, a microgripper is presented which is able to work in aqueous solutions and which is compatible with electrophysiological recordings of the cells immobilized by it. It was successfully employed to position isolated pancreatic islets and a 3D cell culture model of insulin-secreting cells, the so-called MIN6-pseudoislet. As required it was possible to measure the membrane potential of cells within these aggregates without any interference from the microgripper

Determination of density and concentration from fluorescent images of a gas flow

A fluorescent image analysis procedure to determine the distribution of species concentration and density in a gas flow is proposed. The fluorescent emission is due to the excitation of atoms/molecules of a gas that is intercepted by an electron blade. The intensity of the fluorescent light is proportional to the local number density of the gas. When the gas flow is a mixture of different species, this proportionality can be exploited to extract the contribution associated to the species from the spectral superposition acquired by a digital camera. This yields a method that simultaneously reveals species concentrations and mass density of the mixture. The procedure is applied to two under-expanded sonic jets discharged into a different gas ambient - Helium into Argon and Argon into Helium - to measure the concentration and density distribution along the jet axis and across it. A comparison with experimental and numerical results obtained by other authors when observing under-expanded jets at different Mach numbers is made with the density distribution along the axis of the jet. This density distribution appears to be self-similar.Comment: New figures in portable .eps forma

A Disposable Pneumatic Microgripper for Cell Manipulation with Image-Based Force Sensing

A new design for a single-use disposable pneumatic microgripper is presented in this paper. It enables very cost-eective batch microfabrication in SU-8 with a single lithography mask by shifting manufacturing complexity into reusable components. An optically readable force sensor with potential to be used in a feedback loop has been integrated in order to enable gripping with a controlled force. The sensors are first examined separately from the gripper and exhibit good linearity. The gripper function utilizes the disposable gripper element together with a reusable gripper fixture. During experiments, the pneumatically actuated microgripper can vary the gripping force within a range of a few mN (up to 5.7 mN was observed). This microgripper is planned to be used in a liquid environment for gripping larger aggregates of cells in combination with the patch clamp technique. This approach will allow Langerhans islets suspended in an electrolyte solution to be grasped and held during electrophysiological measurements without cell damage

Исследование эколого-технологической эффективности водопользования Томского подземного водозабора

Объектом исследования являются железосодержащие осадки, образующиеся на станции обезжелезивания Томского подземного водозабора. Цель работы – изучение технологии образования железосодержащих осадков при водоподготовке, исследование вещественного состава осадков и рациональных путей их утилизации. В процессе исследования был проведен отбор проб железосодержащих осадков и исследования их вещественного состава в аккредитованных лабораториях ТПУ. В результате исследования выявлен морфологический и вещественный состав новообразований Томского подземного водозабора, а также разработаны рекомендации по их утилизации с учетом технико-экономических особенностей промышленности. Область применения – наиболее рациональные пути использования отходов станции обезжелезивания - использование осадка на химические реактивы – хлорид железа; для стекольной промышленности осадок сульфатов щелочно – земельных металлов; получение неорганических пигментов, в том числе и магнитных; получение строительных материалов, в частности окрашенного отделочного раствора и бетона.Das Untersuchungsobjekt sind eisenhaltige Ablagerungen, die sich in der Wasserenteisenungsanlage der Tomsker Grundwasserfassung bilden. Das Ziel der Studie besteht in der Untersuchung der Herausbildungstechnologie der eisenhaltigen Ablagerungen bei der Wasseraufbereitung, Untersuchung der stofflichen Zusammensetzung der Ablagerungen und Suche nach rationellen Verfahren für deren Verwertung. Im Zuge der Untersuchung wurden Probeentnahme der eisenhaltigen Ablagerungen und deren Untersuchung in den akkreditierten Laboratorien der Tomsker Polytechnischen Universität durchgeführt. Im Ergebnis der Untersuchung wurden stoffliche Zusammensetzung und morphologische Struktur der Neubildungen an der Tomsker Grundwasserfassung offengelegt und die Empfehlungen zu deren Verwertung unter der Berücksichtigung der wirtschaftstechnischen Spezifik der Industrie ausgearbeitet. Anwendungsbereich: effizienteste Verfahren zur Verwertung der Abfälle von der Wasserenteisenungsanlage – Verwendung der Ablagerungen für Chemikalien – Eisenchlorid; Verwendung der abgelagerten Sulfate der Erdalkalimetalle für Glasindustrie; Herstellung der nichtorganischen, inkl. magnetischen Farbpigmente; Verwendung für die Produktion der Baustoffe, insbesondere für die Produktion der gefärbten Nachbehandlungsflüssigkeit und des Betons

The Hydrodynamics of Astrophysical jets: Scaled Experiments and Numerical Simulations

Context. In this paper we study the propagation of hypersonic hydrodynamic jets (Mach number >5) in a laboratory vessel and make comparisons with numerical simulations of axially symmetric flows with the same initial and boundary conditions. The astrophysical context is that of the jets originating around young stellar objects (YSOs). Aims. In order to gain a deeper insight into the phenomenology of YSO jets, we performed a set of experiments and numerical simulations of hypersonic jets in the range of Mach numbers from 10 to 20 and for jet-to-ambient density ratios from 0.85 to 5.4, using different gas species and observing jet lengths of the order of 150 initial radii or more. Exploiting the scalability of the hydrodynamic equations, we intend to reproduce the YSO jet behaviour with respect to jet velocity and elapsed times. In addition, we can make comparisons between the simulated, the experimental, and the observed morphologies. Methods. In the experiments the gas pressure and temperature are increased by a fast, quasi-isentropic compression by means of a piston system operating on a time scale of tens of milliseconds, while the gas density is visualized and measured by means of an electron beam system. We used the PLUTO software for the numerical solution of mixed hyperbolic/parabolic conservation laws targeting high Mach number flows in astrophysical fluid dynamics. We considered axisymmetric initial conditions and carried out numerical simulations in cylindrical geometry. The code has a modular flexible structure whereby different numerical algorithms can be separately combined to solve systems of conservation laws using the finite volume or finite difference approach based on Godunov-type schemes. Results. The agreement between experiments and numerical simulations is fairly good in most of the comparisons. The resulting scaled flow velocities and elapsed times are close to the ones shown by observations. The morphologies of the density distributions agree with the observed ones as well. Conclusions. The laboratory and the simulated hypersonic jets are all pressure matched, i.e. their axial regions are almost isentropic at the nozzle exit. They maintain their collimation for long distances in terms of the initial jet radii, without including magnetic confinement effects. This yields a qualitatively good agreement with the observed YSO jet morphologies. It remains to be seen what happens when non-axially symmetric perturbations of the flow are imposed at the nozzle, both in the experiment and in the simulation

Principles of sensorimotor learning.

The exploits of Martina Navratilova and Roger Federer represent the pinnacle of motor learning. However, when considering the range and complexity of the processes that are involved in motor learning, even the mere mortals among us exhibit abilities that are impressive. We exercise these abilities when taking up new activities - whether it is snowboarding or ballroom dancing - but also engage in substantial motor learning on a daily basis as we adapt to changes in our environment, manipulate new objects and refine existing skills. Here we review recent research in human motor learning with an emphasis on the computational mechanisms that are involved

Human locomotor adaptive learning is proportional to depression of cerebellar excitability

Human locomotor adaptive learning is thought to involve the cerebellum, but the neurophysiological mechanisms underlying this process are not known. While animal research has pointed to depressive modulation of cerebellar outputs, a direct correlation between adaptive learning and cerebellar depression has never been demonstrated. Here, we used transcranial magnetic stimulation to assess excitability changes occurring in the cerebellum and primary motor cortex (M1) after individuals learned a new locomotor pattern on a split-belt treadmill. To control for potential changes associated to task performance complexity, the same group of subjects was also assessed after performing 2 other locomotor tasks that did not elicit learning. We found that only adaptive learning resulted in reduction of cerebellar inhibition. This effect was strongly correlated with the magnitude of learning (r = 0.78). In contrast, M1 excitability changes were not specific to learning but rather occurred in association with task complexity performance. Our results demonstrate that locomotor adaptive learning in humans is proportional to cerebellar excitability depression. This finding supports the theory that adaptive learning is mediated, at least in part, by long-term depression in Purkinje cells. This knowledge opens the opportunity to target cerebellar processes with noninvasive brain stimulation to enhance motor learning