Properties and principles of mycelial flow: a tube rheometer system for fermentation fluids

A tube rheometer system has been constructed for aseptic study of the rheology and fundamental flow properties of mycelial fermentation fluids. The rheometer consists of a U-formed tube circuit starting and ending inside the fermentor. The mash is pumped through the tubes with a lobe rotor pump. The flow is measured by an electromagnetic flow meter. Pressure drops have been measured with a system of differential membrane transducers for different flow rates. The rheometer system was tested with Newtonian and non-Newtonian fluids.     

Heat balance of the human body: influence of variations of locally distributed parameters

Human body temperature control is characterized by a local dependence of system variables and parameters. Essential properties regarding inhomogeneity of the passive system have been investigated using mathematical methods. The general diffusion-equation has been solved using implicit finite difference methods with nonlinear boundary conditions. In order to allow comparison with experimental results, a simple ideal controller has been defined. On the basis of an inhomogeneous cylinder model with four concentric layers, influences of variations due to differences between tissues and individuals or measurements of parameters such as basal metabolism and conductivity have been studied. Stationary temperature profiles calculated for homogeneous and inhomogeneous conditions have been compared. Finally, the influence of blood flow has been discussed, as well as the stationary behaviour of profiles due to blood flow and blood flow control. The change of sign of curvature of temperature profile is possible only if blood flow mechanisms and the local distribution of metabolism are taken into account.     

Imaging in flow.

Imaging in flow has been valuable in investigating discrepancies in flow cell measurements due to cell orientation and flow dynamics. This paper discusses optical consideration in flow imaging, slit and full field imaging systems and various cell motion arresting techniques from the standpoint of image plane exposure and suitable detector choices. It concludes with an explanation of the slit-imaging techniques employed in a multidimensional slit-scan flow system and slit-scan correlation system.     

Laser impact assessment in a biofilm-forming bacterium Pseudoalteromonas carrageenovora using a flow cytometric system

Impact by pulsed laser irradiations from an Nd:YAG laser on the marine biofilm-forming bacterium Pseudoalteromonas carrageenovora has been studied using a flow cytometric system. The biofilm-forming bacteria in the planktonic state have been irradiated while flowing, and the mortality and bacterial attachment have been determined by exposing TiN coupons in the system. Coupons suspended in the non-irradiated bacterial flow were treated as the control. The fluence used in the study was 0.1 J/cm(2). Three flow rates (14, 28, and 42 cm/min) and two exposure durations (15 and 30 min) were tested. The results showed the increase in bacterial mortality with the decrease in flow rate. The maximum mortality of 27.5% was observed when the flow rate was 14 cm/min. The bacterial attachment increased with the increase in flow rate and exposure duration. The area of bacterial attachment on the experimental coupons exposed to the irradiated sample was significantly lesser than that for the nonirradiated sample. The results thus show in a flowing system, low power pulsed laser irradiations could reduce the bacterial attachment even though it did not cause significant mortality.     

An airlift pump device for low pressure perfusion storage of the isolated heart

A portable apparatus for the continuous hypothermic perfusion of the isolated heart is described. The system has been used successfully to store pig and baboon hearts for periods of up to 48 hr, and to store human donor hearts for periods of 7 to 17 hr before being transplanted. The perfusate is both oxygenated and circulated by gas flow from a pressurized oxygen cylinder, using the air-lift pump principle. The apparatus has no moving parts and requires no electrical energy supply; malfunction is, therefore, extremely unlikely. A regulator has been incorporated which can be adjusted to increase or decrease the myocardial perfusion pressure. The system and environmental variables which can affect flow and pressure within the apparatus are discussed. The storage time allowed by this system will enable transportation of donor hearts between most of the world's major cities.     

Design and oxygen-transfer potential of a pulsed continuous tubular fermentor

A new type of continuous fermentor has been developed which features an agitation-aeration system based on pulsed flow across perforated plates the use of plug flow to achieve a concentration gradient. The influence of the agitation-aeration parameters (in this case the pulsed speed) has been measured, and mathematical models have been produced for the gas hold-up, the power dissipated in agitation and aeration, the oxygen-transfer rate, and efficiency. The oxygen transfer is high, up to 600 mmol/liter hr with a transfer efficiency much higher than that published for any other technique.     

Setting up and running a microscope-based flow cytometer

A noncommercial flow cytometry system was set up in a laboratory with no engineering staff attached. The system is based upon a conventional fluorescence microscope and a new flow principle reported by H. Steen and T. Lindmo (Science 204:403, 1979). A few modifications and additions have been introduced. The instrument has proven to be a high-resolution system, easy to adjust and control, giving coefficients of variation of cellular DNA down to 0.8% and of fluorescent polyethylene microspheres down to 0.9%.     

A protocol for Papanicolaou staining of cytologic specimens following flow analysis

A protocol has been developed for restaining cytologic specimens that have been analyzed on a multidimensional slit-scan flow system. The technique involves Papanicolaou staining of cells on a membrane filter that has been previously stained with acridine orange and fixed with glutaraldehyde buffer. The specimen and staining solutions were sequentially added to a 5-micrometers pore size, 47-mm diameter Gelman "Metricel" filter while it remained in a glass filtration apparatus. The practice of retaining the filter in the filtration apparatus throughout the staining procedure minimizes cell loss and eliminates specimen cross contamination when compared with conventional filter dip staining. The availability of this postflow specimen Papanicolaou staining protocol permits accurate determination of the performance characteristics of a multidimensional slit-scan flow system and should be useful whenever staining of a limited number of cells with minimal cell loss is desired.     

A cross-flow reactor with immobilized pectolytic enzymes for juice clarification

Summary A new system for continuous juices clarification is presented. The bioreactor combines microporous plates commercially available and industrial pectinases immobilized on nylon membranes in a cross-flow configuration. The kinetic behaviour of the reactor for different recirculation flow rates has been determined. Fresh apricot juice has been continuously clarified in the bioreactor with excellent results.     

Can Flow Cytometry Reduce the Workload For Cervical Screening? the Results of A Series of 622 Specimens

A simple method permitting the flow cytometric examination of cervical specimens has been developed and an assessment made of the feasibility of relying on this method to screen women for cervical neoplasia. Examination of four flow cytometric parameters showed differences between morphologically normal and abnormal specimens and allowed identification of a proportion of the normal specimens. The system had a false negative rate of 8%. Our experience with cervical specimens has revealed a number of problems associated with their examination by flow cytometry and these are discussed.     

Continuous Synthesis of (R)-(+)-Benzaldehydecyanohydrin Using (R)-Oxynitrilase in Lyotropic Liquid Crystals

The possibility of using the enzyme (R)-Oxynitrilase in a biphasic lyotropic liquid crystal/dibutylether system has been demonstrated. This reaction system is applicable for the continuous production of (R)-benzaldehydecyanohydrin in a fixed bed reactor. The optical purity was between 94 and 96% ee and independent of the flow rate. The space time yield was maximal (2650 g/(1*d)) at a flow rate of 1.6 ml/min.     

Mechanics of blood flow

The historical development of the mechanics of blood flow can be traced from ancient times, to Leonardo da Vinci and Leonhard Euler and up to the present times with increasing biological knowledge and mathematical analysis. In the last two decades, quantitative and numerical methods have steadily given more complete and precise understanding. In the arterial system wave propagation computations based on nonlinear one-dimensional modeling have given the best representation of pulse wave propagation. In the veins, the theory of unsteady flow in collapsible tubes has recently been extensively developed. In the last decade, progress has been made in describing the blood flow at junctions, through stenoses, in bends and in capillary blood vessels. The rheological behavior of individual red blood cells has been explored. A working model consists of an elastic membrane filled with viscous fluid. This model forms a basis for understanding the viscous and viscoelastic behavior of blood.     

A system for storage and retrieval of individual cells following flow cytometry.

A system has been developed to deposit cells in indexed locations on a gelatin-coated film following flow cytometry, allowing the measurements made of individual cells to be correlated with observed morphology or with subsequent microspectrophotometric measurements. Samples are deposited in a continuous track on the film by a deposition nib attached to the flow system below the observation point; laminar flow is preserved by adjusting the tape speed and the flow velocity. Locations of individual cells are indicated by etching the film with a spark triggered by the detection of a cell in the flow cytometer. After deposition, the film is dried by forced warm air. Cells on gelatin may be washed and restained with Papanicolaou and other stains with reasonable preservation of morphology. The system may be used for validation of automated cytodiagnostic procedures based on flow cytometry and for biomedical research.     

A flow system for the study of shear forces upon cultured endothelial cells

A parallel plate chamber in a flow system has been designed to study the effects of fluid shear stresses on cells. The system was applied to the study of cultured endothelial cells grown on cover slips which were accommodated in recessed wells in the base plate. Dye injection studies in the chamber indicated laminar flow over the cells. Shear rates measured over the cover slips by an electrochemical technique were found to be linear with flow rate. Laser doppler anemometry showed parabolic profiles between the plates. Endothelial cells subjected to flow showed a correlation between the time required for orientation and the magnitude of the shear stress.     

Microcomputer-assisted on-line measurement of breathing pattern and occlusion pressure

A flexible system has been developed for on-line breath-by-breath measurements of variables commonly included in studies of breathing pattern and mouth occlusion pressure (P0.1). The system, utilizing analog signals for mouth pressure and inspiratory flow as inputs, includes a breathing pattern monitor and a pneumatically driven occlusion device designed to be compatible with a low-cost microcomputer and analog and/or digital readout instruments. The design of the system permits accurate breathing pattern and P0.1 measurements even at the highest flow and breathing frequency encountered in muscular exercise studies.     

A mathematical model of the flow in the circle of Willis

A mathematical model of the flow in the circle of Willis has been designed and the effects of (a) the large anatomical variation of the communicating arteries and (b) physiological changes of the resistances of the vertebral arteries have been studied. The influence of the posterior perforating arteries on the flow in the posterior communicating arteries has been investigated as well, with special attention being paid to the possible occurrence of a 'dead point'. In the model, the influence of diameters of the communicating arteries on the flow in the afferent vessels and the segments of the circle turns out to be considerable, especially in the range of the anatomical variation of the diameters. Within this range flow reductions due to an increased resistance of the vertebral artery will be compensated for by the system. Assuming that the values and ratios of the peripheral resistances are within the physiological range, a dead point is not to be expected in the flow in the posterior communicating arteries.     

The effect of respiratory activity on brain blood flow during exposure to +Gz acceleration

The effect of respiratory activity on cardiovascular system during the exposure to +Gz acceleration was studied. For simultaneous, beat to beat evaluation of central and global cerebral blood flow, the system based on modified impedance cardiography method was used. The mechanism of modulation of the central and peripheral (cerebral) venous pressures and blood flow by intrathoracic pressure changes, has been shown. The data obtained from these studies suggest that reconsideration of the respiration technique during Anti-GSM seems indispensable.     

Pulsed Doppler ultrasound system for the measurement of velocity distributions and flow disturbances in arterial prostheses

For the investigation of flow through prosthetic arteries a pulsed Doppler ultrasound system has been characterized. Preliminary in vitro experiments using this system are described; they verify its suitability for making velocity profile and flow disturbance measurements. The output from a frequency tracker is compared with spectral analysis of Doppler signals for both laminar and turbulent flow regimes and the root mean square fluctuations on the tracker output signal are used to identify transition from laminar to turbulent flow. In addition, the turbulent itensity of poststenotic flow is quantified at several axial locations and for different rates of flow. Finally, we present velocity profile measurements which were obtained using a deconvolution technique to account for the finite size of the sample volume.     

Improved thermal method of continual recording the transpiration flow rate dynamics

The analysis of the dynamic properties of thermal methods of transpiration flow measurement was performed and the measuring system developed, capable of quantitative measurements of fast flow changes (in minutes). The system is specified with a constant automatically maintained temperature difference between the heated and reference points in the measured part of the plant. System’s output signal related to measured quantity is linear. The system has been under longterm testing in full grown trees using the method of heat balance with direct electric heating of the xylem. The results obtained so far may be considered very good.