Characteristics of Bovine Spermatozoa after Immobilization by Dehydration

Extension of storage time of living animal spermatozoa is of great scientific and economical interest for the breeding industry in Norway. The extension of storage time will leave room to maneuver due to the time limit of artificial insemination of the animals. The aim of this study was to dehydrate semen in order to immobilize the spermatozoa, due to the fact that removal of water molecules leads to higher concentrations of cells and thus might contribute to the physical limitation of motility.

Water was removed from diluted semen by air drying in a convection oven at approximately 33°C. The drying process was continued until there were less than 5% motile spermatozoa. The amount of total solids in the samples increased from approximately 14 to 35% during drying. After immobilization, experiments showed that with specific rehydration temperature (20°C), rehydration medium (skim milk diluents or Beltsville thawing solution), and rehydration rate, the spermatozoa recovered so that up to 70% motility was reestablished.

At the female reproductive organ temperature, motile bull spermatozoa, that was dried and rehydrated, was observed for up to 50% longer periods of time compared to the reference sample.

Membrane destruction caused by drying and/or rehydration of the spermatozoa was detected using plasma membrane integrity. The histograms of reference spermatozoa showed two limited populations, one living and one dead. For the dried and rehydrated samples a third population seemed to emerge. It is presumed that the cell membranes of these spermatozoa might be injured.

It has been demonstrated that spermatozoa immobilized by drying and subsequent rehydration before insemination can cause fertilization and normal embryonic development in cattle.     

NEW APPLICATIONS OF HEAT PUMPS IN DRYING PROCESSES

Heat pumps in combination with fluidized bed driers have been investigated extensively at The Norwegian Institute of Technology. A laboratory plant was constructed and a series of experiments on different types of temperature sensitive products were executed. By using heat pump, good temperature and humidity regulation is achieved. Drying temperatures can be regulated from -20°C to 50°C. This gives the possibility of freeze-drying at atmospheric pressure, and drying at temperatures above 0°C in the same plant. By using a temperature program, including an initial period of freeze drying, it is possible to regulate the products' physical properties. Examples are: the sinking velocity of fish fry feed, rehydration ability, colour and taste of dried fish, meat and vegetable products. Further, biotechnological products like bacterial cells and biomolecules/enzymes were dried with improved biological activity of the products compared to traditional drying methods like vacuum freeze drying or spray drying.     

Can Drying Be an Alternative Tissue Preservation Method in Cancer Research Biobanking?

The currently available methods for conservation of biobank material are mainly based on formalin fixation or the use of different freezing techniques. For molecular biological analysis, it is common to use quick freezing and low-temperature storage of the tissue materiel. This is a very energy-intensive and expensive method that requires advanced infrastructure, including monitoring and control procedures. The purpose of this work has been to study drying as an alternative process to cryogenic storage of undried biobank material, especially for use in cancer research groups.

Fast freezing has been shown to be suitable to preserve the integrity of RNAs, while traditional formalin fixation preserves proteins and thus morphology in a good way. Various fresh-harvested murine tissues, such as lung, heart, skeletal muscle, liver, and kidney, were quickly frozen in liquid nitrogen and then subsequently dried at +5°C and ?10°C, respectively, in a heat pump dryer. After drying, the RNA integrity was measured. The dried material was then stored for five months at +4°C and ?20°C in commercial refrigerators, with subsequent measurement of RNA integrity. Dried materials were also evaluated with light microscopy and by electron microscopy with respect to tissue and cell structure. The same pattern was found for all five murine tissues. We conclude that drying at temperatures below 0°C is most careful to preserve the RNA integrity, with approximately the same RIN score of dried and non-dried samples for all five tissues. What characterized the general pattern of stored samples is that drying leads to a preservation of RNA integrity. Moreover, architecture in tissue resembled normal sections prepared from fresh tissue. In some places in the rim of the tissue sample, the lung tissue revealed alveolar-like morphology. In the electron microscope, few organelles other than the nuclei could be identified. Drying of biological material is a promising and cost-effective method for biobanks that store tissue, compared to cryogenic storage of undried material. Degradation of RNA, measured by the RIN number, is a critical factor in storing biobank tissue. In low-temperature dried material, the RIN factor is at the same level as storage of undried material at cryogenic temperatures, which is the common way of storing biobank material today. In this study, a heat pump dryer was used successfully to establish drying temperatures below and above the freezing point of the material. Further work has to be done in order to study different drying methods, drying conditions, and drying costs.     

A Simulation Model for Heat Pump Dryer Plants for Fruits and Roots.

ABSTRACT

Dryer design requires food properties, drying rate and mass-heat transfer coefficients. These values change continuously during drying due to changes in food fractions, particularly the water fraction. The high energy demand and costs allied to inefficient devices, creates a great need for new processing equipment. Along these guide-lines, several heat pump drying research projects were established at the Norwegian University of Science and Technology. The heat pump dryer provides high quality final product as its drying conditions can be controlled. Its efficiency and non-polluting operation come from closed air-refrigerant circuits and from its ability to fully recover the latent heat of moist air as it exits the drying chamber. Most of the above features are quite the opposite of the conventional dryer characteristics. Several experiments were made on heat pump drying of fruits and roots at temperatures from -22.5 to 40°C to obtain data and correlations on thermophysical properties, specific enthalpy and rehydration. Also, tests were done on drying rate, moisture content, drying constant, effective mass diffusivity and heat and mass transfer equations. The next important phase is the development of a simulation model to predict the performance and characteristics of the heat pump dryer plant. The objectives of the present work are to develop and lo test a heat pump dryer simulation model. The simulation provides results on the characteristics of both plant and components which are integrated by heat and mass transfer equations. The program has menus with click-on icons, input and output pop-up dialogue boxes. The usual commands such as, file-open, file-save, edit-delete are available in this program simply called Hpdryer. The model contains moist air psychrometric. natural and conventional refrigerant property libraries. Ammonia is a time-tested, self-alarming and natural refrigerant. It has been used extensively in the past, and it has better thermodynamic and transport properties than halocarbons. Safety is easily attained by design and its restrictive standards have helped increase its use in several countries. There are 36 ammonia installations in Norway and in the United Kingdom, including a drying plant. Ammonia has zero Odp, zero Gwp and the recent R&D has led to viable small-sale heat pump plants. Ammonia and dichlarodifluoromethane refrigerants were used in the test cases simulated by Hpdryer madel.     

A Simulation Model for Heat Pump Dryer Plants for Fruits and Roots.

Dryer design requires food properties, drying rate and mass-heat transfer coefficients. These values change continuously during drying due to changes in food fractions, particularly the water fraction. The high energy demand and costs allied to inefficient devices, creates a great need for new processing equipment. Along these guide-lines, several heat pump drying research projects were established at the Norwegian University of Science and Technology. The heat pump dryer provides high quality final product as its drying conditions can be controlled. Its efficiency and non-polluting operation come from closed air-refrigerant circuits and from its ability to fully recover the latent heat of moist air as it exits the drying chamber. Most of the above features are quite the opposite of the conventional dryer characteristics. Several experiments were made on heat pump drying of fruits and roots at temperatures from -22.5 to 40°C to obtain data and correlations on thermophysical properties, specific enthalpy and rehydration. Also, tests were done on drying rate, moisture content, drying constant, effective mass diffusivity and heat and mass transfer equations. The next important phase is the development of a simulation model to predict the performance and characteristics of the heat pump dryer plant. The objectives of the present work are to develop and lo test a heat pump dryer simulation model. The simulation provides results on the characteristics of both plant and components which are integrated by heat and mass transfer equations. The program has menus with click-on icons, input and output pop-up dialogue boxes. The usual commands such as, file-open, file-save, edit-delete are available in this program simply called Hpdryer. The model contains moist air psychrometric. natural and conventional refrigerant property libraries. Ammonia is a time-tested, self-alarming and natural refrigerant. It has been used extensively in the past, and it has better thermodynamic and transport properties than halocarbons. Safety is easily attained by design and its restrictive standards have helped increase its use in several countries. There are 36 ammonia installations in Norway and in the United Kingdom, including a drying plant. Ammonia has zero Odp, zero Gwp and the recent R&D has led to viable small-sale heat pump plants. Ammonia and dichlarodifluoromethane refrigerants were used in the test cases simulated by Hpdryer madel.     

The entire compound autosomes of Drosophila melanogaster

Three new unusual compound chromosomes have been synthesized in Drosophila melanogaster. They consist of two homologous autosomes joined together in the new order: right arm, left arm, centromere, left arm, right arm, for each of the two major autosomes, and one in which chromosomes 2 and 3 have been combined in the order: right arm of 2, left arm of 2, centromere, left arm of 3, right arm of 3. The attachments of the autosomal arms were accomplished by obtaining chromosome breaks at or very close to the ends of the left arms of the autosomes such that no essential chromosome material has been removed; the compounds derived from them are therefore referred to as entire compounds. These large chromosomes are recovered in progeny with frequencies lower than expectation partly because of zygote mortality associated with these chromosomes, and partly because of a failure of spermiogenesis.     

Collection of biological and non-biological particles by new and used filters made from glass and electrostatically charged synthetic fibers

Synthetic filters made from fibers carrying electrostatic charges and fiberglass filters that do not carry electrostatic charges are both utilized commonly in heating, ventilating, and air-conditioning (HVAC) systems. The pressure drop and efficiency of a bank of fiberglass filters and a bank of electrostatically charged synthetic filters were measured repeatedly for 13 weeks in operating HVAC systems at a hospital. Additionally, the efficiency with which new and used fiberglass and synthetic filters collected culturable biological particles was measured in a test apparatus. Pressure drop measurements adjusted to equivalent flows indicated that the synthetic filters operated with a pressure drop less than half that of the fiberglass filters throughout the test. When measured using total ambient particles, synthetic filter efficiency decreased during the test period for all particle diameters. For particles 0.7-1.0 mum in diameter, efficiency decreased from 92% to 44%. It is hypothesized that this reduction in collection efficiency may be due to charge shielding. Efficiency did not change significantly for the fiberglass filters during the test period. However, when measured using culturable biological particles in the ambient air, efficiency was essentially the same for new filters and filters used for 13 weeks in the hospital for both the synthetic and fiberglass filters. It is hypothesized that the lack of efficiency reduction for culturable particles may be due to their having higher charge than non-biological particles, allowing them to overcome the effects of charge shielding. The type of particles requiring capture may be an important consideration when comparing the relative performance of electrostatically charged synthetic and fiberglass filters. PRACTICAL IMPLICATIONS: Electrostatically charged synthetic filters with high initial efficiency can frequently replace traditional fiberglass filters with lower efficiency in HVAC systems because properly designed synthetic filters offer less resistance to air flow. Although the efficiency of charged synthetic filters at collecting non-biological particles declined substantially with use, the efficiency of these filters at collecting biological particles remained steady. These findings suggest that the merits of electrostatically charged synthetic HVAC filters relative to fiberglass filters may be more pronounced if collection of biological particles is of primary concern.     

Atmospheric Freeze Drying—Modeling and Simulation of a Tunnel Dryer

Drying is an important unit operation in processing of foods and other biotechnological products. Vacuum freeze drying is said to be the best drying technology regarding product quality of the end product, but the disadvantages are, among others, expensive operational costs and batch drying. Atmospheric freeze drying was introduced to lower the production costs of high-quality dried foods, and the need of simulation tools became important in estimations of the industrial drying processes.

A simplified mathematical model (AFDsim) is developed based on uniformly retreating ice front (URIF) considerations. The model is used to calculate theoretical drying curves of atmospheric freeze dried foods in a tunnel dryer. Studies of thermal and mass transfer properties during drying are essential for understanding the changes in product quality and for designing and dimensioning the drying process. The model can be used to simulate industrial atmospheric freeze drying of different foodstuff in a tunnel. The results from AFDsim modeling are in good accordance with the experimental results.     

Relationship of Product Structure,Sorption Characteristics,and Freezing Point of Atmospheric Freeze-Dried Foods

Drying is an important unit operation in processing of foods with a long shelf life. The drying process influences product properties and quality; the products may shrink, break, or undergo rheological, physical, and biochemical changes. Important parameters responsible for product quality changes during drying are temperature, relative humidity, and residence time. Studies of thermal and mass transfer properties during drying are essential for understanding the changes in product quality and for designing and dimensionalizing the drying process.

Drying kinetics, sorption properties, shrinkage, and freezing point depression were determined during atmospheric freeze drying (AFD) of pieces of apple, turnip cabbage, and cod. Adsorption rate and sorption isotherms were determined in the end product. The drying temperature affected the physical properties. Drying at ?5°C resulted in a larger shrinkage than drying at ?11°C. GAB modeling was used to characterize the sorption properties of the products. No typical sigmoidal shape was found of the moisture sorption isotherms of the products, which is in accordance with the Guggenheim constant found from the same results. Experimental data on freezing point depression were used to find product constants E and b in the Schwartzberg equation for the freezing point depression. Freezing point depression, as a function of the dry matter content, was determined using Schwartzberg's equation and a component composition model (CCM). The result indicates an influence of structural effects on freezing point depression.     

Slow and steady wins the race? Three-year-old children and pointing device use

While adult performance with different pointing devices has received extensive study in the human-computer interaction literature, there is little data on the performance of young children using any input devices at all. In the present study, 64 three-year-old children used a joystick, mouse, or trackball to perform a simple cursor placement task. Two substantive results were obtained. First, trackball users were the slowest, but also the most accurate in their cursor control. Second, characteristics of the children's performance suggest that adult standards for an optimal interface, which stress speed and efficiency, may not be appropriate when children are the intended users.