Instrumentation and Computer Interface of an Automated Experimental Cryopreservation Apparatus

ABSTRACT

A process suitable for cooling and warming the isolated rat heart by a perfusion technique was designed, built, automated and tested in the areas of normothermia, hypothermia, cryopro-tectant (CPA) administration and cooling to -22°C. The major benefits were in the application of computer control technology to a complex field like cryopreservation with promising results.     

An econometric analysis of energy input–output in Turkish agriculture

This study analyzes energy use and investigates influences of energy inputs and energy forms on output levels in Turkish agriculture during the period 1975–2000. The output level was calculated in the form of annual grain equivalent at aggregate level for 104 agricultural commodities except livestock products. Output level was specified as a function of total physical, fertilizer and seed energy, and ordinary least squares was employed to estimate equation parameters. The results show that total energy input has increased from 19.6 GJ/ha in 1975 to 45.7 GJ/ha in 2000, whereas total output energy has risen from 27.1 GJ/ha to a level of 39.1 GJ/ha. Energy efficiency indicators, input–output ratio, energy productivity and net energy have declined over the examined period. Total physical and fertilizer energy, particularly nitrogen, significantly contributed to output level with elasticities of 0.24 and 0.14, respectively. The results also revealed that non-renewable, direct and indirect energy forms had a positive impact on output level. Moreover, Turkish agriculture has experienced a substantial increase in non-renewable energy use. This inefficient energy use pattern in the Turkish agriculture can create some environmental problems such as increase in global warming, CO₂ emissions, and non-sustainability. Thus, policy makers should undertake new policy tools to ensure sustainability and efficient energy use.     

Abundance of the longer A beta 42 in neocortical and cerebrovascular amyloid beta deposits in Swedish familial Alzheimer's disease and Down's syndrome

Recent studies have demonstrated the deposition of amyloid beta (A beta) protein with carboxyl- and aminoterminal heterogeneity in cortical and cerebrovascular deposits of Alzheimer's disease (AD). Using carboxyl end-terminal specific antibodies to A beta peptides, we examined the immunocytochemical distribution of A beta 40 and A beta 42 species in brain tissue from a Swedish subject with familial AD (FAD) bearing the double mutation at codons 670/671 in the amyloid beta precursor protein (A beta PP), and from subjects with Down's syndrome and sporadic AD. In the Swedish subject, we found profound parenchymal A beta deposits and cerebral amyloid angiopathy in all four cortical lobes and cerebellum. A beta 42 was evident in almost all parenchymal deposits as well as many vascular deposits. Although A beta 40 was present in meningeal and intraparenchymal vessels, deposits containing this shorter peptide reactivity were sparse. Surprisingly, our observations in Swedish FAD showing a remarkable abundance of A beta 42 in both parenchymal and vascular deposits were qualitatively similar to the Down's syndrome and most sporadic AD cases, and to previously published A beta PP717 FAD. While previous transfection studies in different cell cultures indicate substantially increased soluble A beta production and A beta 40 species to be predominant, it would appear that the double A beta PP mutations in Swedish FAD largely result in the deposition of the longer A beta 42 in vivo.     

Handoff effect on packet reservation multiple access (PRMA) in microcellular system

Packet reservation multiple access (PRMA) has been proposed for third-generation wireless information networks by D.J. Goodman and S.X. Wei (see ibid., vol.40, p.170-6, 1991). The mobile-initiated handoff has been proposed to disperse the base station (BS) burden, which is increased by the small microcell radius. However, increased contentions, due to handoff, affect the overall performance of PRMA, even though these frequent handoffs do not burden the BS. We analyze the handoff effect on PRMA performance under a microcellular system, both voice-only and combined voice-and-data systems. A steady state voice-terminal model with handoff is proposed. System-equilibrium equations are derived using the proposed model. The system performance is evaluated, using a Markov analysis method, in terms of packet-dropping probability, data-packet delay, and throughput. The change of performance under handoff show the impact of handoff on PRMA.     

Review of methods for predicting in situ volume change movement of expansive soil over time

The soil movement information over time is required for the design of foundations placed in expansive soils. This information is also helpful for the assessment of pre-wetting and controlled wetting mitigation alternatives for expansive soils. Several researchers during the past fifteen years have proposed different methods for the prediction of the soil movements over time. The available methods can be categorized into(i) consolidation theory-based methods,(ii) water content-based methods, and(iii) suction-based methods. In this paper, a state-of-the-art of the prediction methods is succinctly summarized. The methods are critically reviewed in terms of their predictive capacity along with their strengths and limitations. The review highlights the need for prediction methods that are conceptually simple yet efficient for use in conventional engineering practice for different types of expansive soils.     

A cis-directing effect towards diols by an exocyclic P-NHR moiety in cyclotriphosphazenes

Cyclophosphazenes containing the P-NHR moiety in an exocyclic spiro ring, N₃P₃Cl₄[NH(CH₂)₃O], (1), and N₃P₃Cl₄[NH(CH₂)₃NMe], (2), were used to investigate a possible directing effect of the P-NHR moiety on the formation of products in the nucleophilic substitution reactions with diols such as tetraethyleneglycol, 1,3-propanediol and 2,2-dimethyl-1,3-propanediol. The ³¹P NMR spectra of the reaction mixtures showed that only one kind of ansa product is formed in each of these reactions. X-ray crystallographic studies of the ansa products [(4a), (5a), (6a) and (7a)] have provided definitive proof of the cis-directing effect of the P-NHR moiety in cyclotriphosphazenes. It is likely that hydrogen-bond interaction between the incoming nucleophile and the P-NHR moiety of the reactant accounts for the preference for products with the substituents cis to the NH group.     

Importance of geothermal energy and its environmental effects in Turkey

Geothermal energy, a relatively benign energy source when compared with other energy sources due to reduction in greenhouse gas emissions, is used for electricity generation and direct utilization. Turkey has a place among the first seven countries in the world in the abundance of geothermal resources, but it has only used about 4% of its potential. The paper presents the status of energy needs and renewables, potential, utilization and the importance of geothermal energy in Turkey. It also gives a comparison between geothermal energy and other energy sources regarding environmental issues. It is estimated that if the geothermal heating potential alone in Turkey is used, 5 million residences will be heated and as a result, releases of 48 million ton/year CO₂ emissions into the atmosphere will be prevented. In addition to this, if the other geothermal potential (i.e. electricity) is used it will provide considerable environmental benefits. Therefore, it is expected that geothermal energy development will significantly speed up in the future.     

A measurement-based prioritization scheme for handovers in mobilecellular networks

A method of improving the quality of service in mobile cellular systems based on prioritization of handover requests is presented. The objective is to improve perceived quality of cellular service by minimizing both the probability of forced termination of ongoing calls due to handover failures and the degradation in spectrum utilization. A model based on a multiple-priority nonpreemptive queuing discipline is developed. New calls are blocked if all channels are occupied. Handover requests are queued such that as soon as a channel is available, it is offered to the mobile subscriber with the measurement results closest to the minimum acceptable power level for communication. Service rate is given by channel occupancy time distribution and is assumed to be exponential. The performance of a cellular system employing the proposed handover policy is evaluated analytically and by simulation, and results are compared to those obtained when the cellular system employs nonprioritized call handling and first-in/first-out queuing discipline. This provides lower probability of forced termination and less call blocking, less reduction in traffic, and less delay     

Effect of the infestation by Prostephanus truncatus Horn, Sitophilus zeamais Mots, or Sitotroga cerealella Oliver, on the concentration of amino acids in corn proteins

The amino acid concentration in the protein of batches of corn kernel subjected to infestation by P. truncatus, S. zeamais or S. cerealella was measured. For each insect species three development stages were studied, larvae, at the emergence of the first generation, and longer. Differences between the control and each of the nine infested batches were observed for most of the amino acids. The only pattern of differences consistent in magnitude, significance and sign, was a fall in leucine and isoleucine and a raise in tryptophan concentration. The chemical scores of all samples were similar to the control, except in the case of infestation by larvae of S. cerealella in which it decreased 15%.     

Optimization of cutting parameters on drill bit temperature in drilling by Taguchi method

In this study, the optimization of the cutting parameters on drill bit temperature in drilling was performed. Al 7075 work piece and the uncoated and Firex® coated carbide drills in the experimental were used. The optimization of the cutting parameters was evaluated by Taguchi method. The control factors were considered as the cutting speed, feed rate and cutting tool. Taguchi method was used to determining the settings of cutting parameters. The L₁₈ orthogonal array was used in experimental planning. The most significant control factors affected on drill bit temperature measurements was obtained by using analysis of variance (ANOVA). Taguchi design method exhibit a good performance in the optimization of cutting parameters on drill bit temperature measurements. In addition, the empirical equations of drill bit temperatures were derived by using regression analysis. The obtained equations results compared with the drill bit temperature measurement results. The empirical equations results indicated a good agreement with experimental results.