bluuebunny/crossref_metadata_2025 huggingface dataset:
Applied Ultrasonic Technology in Wellbore-Leak Detection and Case Histories in Alaska North Slope Wells
Authors: Johns J. E. , Blount C. G. , Dethlefs J. C. , Loveland M. J. , McConnell M. L. , Schwartz G. L. , Julian J. Y.
Published: July 2009

When operators are faced with well-integrity problems, a variety of methods may be used to detect the source of annular communication. Methods for detecting downhole leak points include spinners, temperature logs, downhole cameras, thermal-decay logs, and noise logs. However, many of these methods are ineffective when dealing with very small leaks and can result in collected data that require a significant amount of logging finesse to interpret.

Ultrasonic listening devices have been used for a number of years to detect leak sources effectively in surface production equipment. Ultrasonic energy has some properties that, when compared to audible-frequency energy, make it ideal for accurate leak detection (Beranek 1972; Povey 1997; Evans and Bass 1972). Like audible-frequency energy, ultrasonic energy can pass through steel. However, ultrasonic energy propagates relatively short distances through fluids when compared to equal-energy audible-frequency sound. Thus, when an ultrasonic signal of this nature is detected, the detection tool will be in close proximity to the energy source.

On this premise, an ultrasonic leak-detection tool was developed for downhole applications to take advantage of the unique properties of ultrasonic-energy propagation through various media. Data-acquisition equipment and filtering algorithms were developed to allow continuous logging conveyed on standard electric line at common logging speeds. Continuous logging has proved to be significantly more efficient in locating anomalies than static logging techniques commonly used in noise-logging operations.

During development, the tool was shown to be effective in locating leaks as small as 0.026 gal/min with an accuracy of 3 ft in production tubing, casing, and other pressure-containing completion equipment. Leaks also have been detected through multiple strings of tubing and casing. The tool has proved to be effective in locating leaks that other diagnostic methods were unable to locate.
Drilling and Completing High-Angle Wells in High-Density, Cesium Formate Brine—The Kvitebjørn Experience, 2004-2006
Authors: Berg Per Cato , Pedersen Erik Sandtorv , Lauritsen Åshild , Behjat Nader , Hagerup-Jenssen Siri , Howard Siv , Olsvik Gunnar , Downs John D. , Turner Jim , Harris Mike
Published: July 2009

Drilling and completion fluids based on cesium formate brines were selected by Statoil for use in the development of the high-pressure/high-temperature (HP/HT) Kvitebjørn field. CsFo brine was selected primarily to minimize well-control problems and maximize well productivity. These important benefits had been recognized by Statoil in previous HP/HT drilling and completion operations over the past 5 years. The use of the same fluid system for both drilling and completion gives the additional benefits of simplified operations, reduced waste, and elimination of fluid-incompatibility problems.

The challenge on the Kvitebjørn field was to drill long, deviated well paths through significant sequences of shales into reservoirs with pressures as great as 81 MPa (11,700 psi) and temperatures up to 155°C (311°F). So far, the CsFo brine has enabled the successful drilling and completion of seven high-angle, HP/HT production wells on Kvitebjørn, two completed with a cemented/perforated liner and five with sand screens.

Additionally, an extended-reach exploration well was drilled from the Kvitebjørn platform to the Valemon structure. The 705-m (2,313-ft) -long reservoir section of this 7380-m (24,213-ft) -long well with an inclination of 69° was drilled successfully with the same CsFo fluid system.

In all these wells, the CsFo-brine system once again demonstrated clear performance benefits such as very low equivalent circulating densities (ECDs), moderate-to-high rates of penetration (ROPs), good hole cleaning, and excellent wellbore stability while logging. Quick, trouble-free, safe, and robust completion operations were also accomplished, and the wells that have been put on production show high production rates with low skin.

Full openhole formation evaluation of the Kvitebjørn reservoir has been carried out successfully with logging-while-drilling (LWD) tools. The evaluation has been aided by the development of a novel logging-interpretation solution for a LWD density tool, in which the extremely high photoelectric effect of cesium-rich filtrate plays a vital role.

CsFo brine has helped Statoil to achieve a record of zero well-control incidents in all 15 HP/HT-drilling operations and 20 HP/ HT-completion operations in the Kvitebjørn, Kristin, and Huldra fields over a period of 5 years.
A Breakthrough Technology for Maximizing Water Injectivity and Asset Integrity
Authors: Horsup David I.
Published: July 2009

The importance of maintaining oil production has never been more critical than it is today. For many fields using water injection to maintain reservoir pressure, the injection rate can decline over time because of the blocking of pore throats in the near wellbore region. Remediation can be expensive, incur lost production, and expose operations personnel to hazardous chemicals. Additionally, the material that blocks the pore throats also deposits within the injection infrastructure, resulting in significant asset-integrity challenges. This paper describes a new technology that has been developed that can increase significantly water injectivity, potentially prevent well interventions, maximize production, and preserve the integrity of the injection infrastructure.

Through extensive research, a new, patented, multifunctional product has been developed that, when injected into the water injection system, cleans away deposits, prevents new deposits from forming, and provides corrosion inhibition to the injection infrastructure. This paper discusses the research that was performed to develop this new technology and the results of several field applications.
Horizontal Wells in Tight Gas Sands— A Method for Risk Management To Maximize Success
Authors: Baihly Jason , Grant Dee , Fan Li , Bodwadkar Suhas
Published: July 2009

In general, successful applications of horizontal wells have been limited to high-permeability reservoirs and unconventional formations such as coal, chalk, and shale. Conversely, few tight-gas-sandstone reservoirs that require stimulation have realized sustained success with horizontal completions. One example of such success is the Cleveland Sand of north Texas and the Oklahoma Panhandle. Very recently, some success with horizontals has been observed in the Bossier and Cotton Valley Sands of East Texas and north Louisiana. Horizontal wells are commonly two to four times more expensive to drill and complete than offset vertical wells, yet they are theoretically capable of up to three to five times the production. Higher gas prices have lead to potentially better economics for horizontal wells (Mulder et al. 1992). However, research shows that in practice, many of these wells typically produce only 10 to 30% more than offset vertical wells. With costs more than double those of vertical wells, the economics is obviously unfavorable.

This paper discusses ways to identify and manage risks when planning, drilling, and completing horizontal wells in tight-sandstone formations to improve success.

Evidence has shown that shortcuts and blanket approaches do not work usually in these completion environments. A multitude of lithological and depletion possibilities exist as risks that need to be identified and managed through appropriate application of integrated drilling and completion technologies. Each risk may require different drilling and completion considerations in order to succeed. There is simply no recipe for repeat success.

A detailed method is presented to identify, understand, and manage risk associated with horizontal wells drilled in tight-gas-sandstone reservoirs. The method will address all of the complex subjects that need to be considered for the successful placement and completion of a horizontal well, including reservoir description (both static and dynamic), well design, drilling, stimulation, and production. It will also illustrate consequences of what may happen if these issues are not considered properly. Through this method, horizontal-well feasibility and economic results can be determined. If a horizontal well has been determined to be viable economically, this method can consistently provide a solution as to what the best completion type (vertical or horizontal) is to recover reserves and enhance recovery efficiency in tight-gas-sandstone reservoirs.
A Sensitivity Analysis for Effective Parameters on 2D Fracture-Network Permeability
Authors: Jafari A. , Babadagli T.
Published: July 2009

Fracture-network mapping and estimation of its permeability constitute two major steps in static-model preparation of naturally fractured reservoirs. Although several different analytical methods were proposed in the past for calculating fracture-network permeability (FNP), different approaches are still needed for practical use. We propose a new and practical approach to estimate FNP using statistical and fractal characteristics of fracture networks. We also provide a detailed sensitivity analysis to determine the relative importance of fracture-network parameters on the FNP in comparison to single-fracture conductivity using an experimental-design approach.

The FNP is controlled by many different fracture-network parameters such as fracture length, density, orientation, aperture, and single-fracture connectivity. Five different 2D fracture data sets were generated for random and systematic orientations. In each data set, 20 different combinations of fracture density and length for different orientations were tested. For each combination, 10 different realizations were generated. The length was considered as constant and variable. This yielded a total of 1,000 trials. The FNPs were computed through a commercial discrete-fracture-network (DFN) modeling simulator for all cases. Then, we correlated different statistical and fractal characteristics of the networks to the measured FNPs using multivariable-regression analysis. Twelve fractal (sandbox, box counting, and scanline fractal dimensions) and statistical (average length, density, orientation, and connectivity index) parameters were tested against the measured FNP for synthetically generated fracture networks for a wide range of fracture properties. All cases were above the percolation threshold to obtain a percolating network, and the matrix effect was neglected.

The correlation obtained through this analysis using four data sets was tested on the fifth one with known permeability for verification. High-quality match was obtained.

Finally, we adopted an experimental-design approach to identify the most-critical parameters on the FNP for different fracture-network types. The results are presented as Pareto charts.

It is believed that the new method and results presented in this paper will be useful for practitioners in static-model development of naturally fractured reservoirs and will shed light on further studies on modeling and understanding the transmissibility characteristics of fracture networks. It should be emphasized that this study was conducted on 2D fracture networks and could be extended to 3D models. This, however, requires further algorithm development to use 2D fractal characteristics for 3D systems and/ or development of fractal measurement techniques for a 3D system. This study will provide a guideline for this type of research.
Design and Life-Cycle Considerations for Unconventional-Reservoir Wells
Authors: Miskimins Jennifer L.
Published: July 2009

This paper provides an overview of design and life-cycle considerations for certain unconventional-reservoir wells. An overview of unconventional-reservoir definitions is provided. Well design and life-cycle considerations are addressed from three aspects: upfront reservoir development, initial well completion, and welllife and long-term considerations.

Upfront-reservoir-development issues discussed include well spacing, well orientation, reservoir stress orientations, and tubular metallurgy. Initial-well-completion issues include maximum treatment pressures and rates, treatment diversion, treatment staging, flowback and cleanup, and dewatering needs. Well-life and longterm discussions include liquid loading, corrosion, refracturing and associated fracture reorientation, and the cost of abandonment.

These design considerations are evaluated with case studies for five unconventional-reservoir types: shale gas (Barnett shale), tight gas (Jonah feld), tight oil (Bakken play), coalbed methane (CBM) (San Juan basin), and tight heavy oil (Lost Hills field). In evaluating the life cycle and design of unconventional-reservoir wells, "one size" does not fit all and valuable knowledge and a shortening of the learning curve can be achieved for new developments by studying similar, more-mature fields.
Miscible-Type Waterflooding: Oil Recovery with Micellar Solutions
Authors: Gogarty W.B. , Tosch W.C.
Published: July 2009

A new recovery process for producing oil under both secondary and tertiary conditions utilizes the unique properties of micellar solutions (also known as microemulsions, swollen micelles, and soluble oils). These solutions, which displace 100 percent of the oil in the reservoir contacted, can be driven through the reservoir with water and are stable in the presence of reservoir water and rock. Basic components of micellar solutions are surfactant, hydrocarbon and water. They may also contain small amounts of electrolytes and co-surfactants such as alcohols. The specific reservoir application dictates the type and concentration of each component. A salient feature of the process is the capability for mobility control. Micellar solution slug mobility, by way of viscosity control, is made equal to or less than the combined oil and water mobility. Mobility control continues with a mobility buffer that prevents drive water from contacting the micellar solution. Laboratory and field flooding have proven that the process is technically feasible and that surfactant losses by adsorption on porous media are small.

Introduction

Projects are under way to recover the maximum amount of oil under the most favorable economic conditions.

New techniques are being developed to increase oil recovery. Polymer solutions are becoming an important means of controlling mobility in a waterflood. Thermal methods such as in-situ combustion and steam injection are being used in reservoirs containing highly viscous crudes. Surfactant flooding is receiving attention as a method of reducing interfacial tension to increase recovery. Exotic recovery processes have been considered primarily for secondary operations. Economics are unfavorable in most cases for tertiary recovery.

Studies at the Denver Research Center of the Marathon Oil Co. have led to a new oil recovery method. Micellar solutions (sometimes called microemulsions, swollen micelles, and soluble oils) are used to recover oil by miscible-type waterflooding. Basically, these solutions contain surfactant, hydrocarbon, and water. The method can be used in either secondary or tertiary operations.
Adipose Tissue Plasticity During Catch-Up Fat Driven by Thrifty Metabolism
Authors: Summermatter Serge , Marcelino Helena , Arsenijevic Denis , Buchala Antony , Aprikian Olivier , Assimacopoulos-Jeannet Françoise , Seydoux Josiane , Montani Jean-Pierre , Solinas Giovanni , Dulloo Abdul G.
Published: July 2009

OBJECTIVE

Catch-up growth, a risk factor for later type 2 diabetes, is characterized by hyperinsulinemia, accelerated body-fat recovery (catch-up fat), and enhanced glucose utilization in adipose tissue. Our objective was to characterize the determinants of enhanced glucose utilization in adipose tissue during catch-up fat.

RESEARCH DESIGN AND METHODS

White adipose tissue morphometry, lipogenic capacity, fatty acid composition, insulin signaling, in vivo glucose homeostasis, and insulinemic response to glucose were assessed in a rat model of semistarvation-refeeding. This model is characterized by glucose redistribution from skeletal muscle to adipose tissue during catch-up fat that results solely from suppressed thermogenesis (i.e., without hyperphagia).

RESULTS

Adipose tissue recovery during the dynamic phase of catch-up fat is accompanied by increased adipocyte number with smaller diameter, increased expression of genes for adipogenesis and de novo lipogenesis, increased fatty acid synthase activity, increased proportion of saturated fatty acids in triglyceride (storage) fraction but not in phospholipid (membrane) fraction, and no impairment in insulin signaling. Furthermore, it is shown that hyperinsulinemia and enhanced adipose tissue de novo lipogenesis occur concomitantly and are very early events in catch-up fat.

CONCLUSIONS

These findings suggest that increased adipose tissue insulin stimulation and consequential increase in intracellular glucose flux play an important role in initiating catch-up fat. Once activated, the machinery for lipogenesis and adipogenesis contribute to sustain an increased insulin-stimulated glucose flux toward fat storage. Such adipose tissue plasticity could play an active role in the thrifty metabolism that underlies glucose redistribution from skeletal muscle to adipose tissue.
Severe polymyositis and neuritis in a cat
Authors: Ginman Adam A. , Kline Karen L. , Shelton G. Diane
Published: July 2009

Case Description—A 4-year-old domestic shorthair cat was evaluated for a 1-week history of shifting limb lameness that progressed to tetraparesis.

Clinical Findings—Physical examination revealed generalized muscle atrophy and signs of discomfort when the muscles of the appendicular skeleton were palpated. Neurologic examination revealed diminished myotatic and withdrawal reflexes in all 4 limbs. Results of a CBC indicated mild neutrophilia, and serum biochemical analysis revealed mild hyperalbuminemia and high creatine kinase activity. The cat was anesthetized, and an electromyogram (EMG), CSF sample, and nerve and muscle biopsy specimens were obtained. The EMG revealed positive sharp waves and fibrillation potentials, CSF analysis revealed albuminocytologic dissociation, and histologic examination of muscle and nerve specimens revealed severe myositis and neuritis. Immune-mediated polymyositis and neuritis were suspected.

Treatment and Outcome—With physical therapy and long-term corticosteroid drug treatment, the cat recovered complete motor nerve function.

Clinical Relevance—The severity and rapid progression of clinical signs, combined with the EMG abnormalities and histologic findings, could have led to inappropriate euthanasia for this cat. Veterinarians should be aware that immune-mediated polymyositis and neuritis in cats can have an excellent prognosis with appropriate, long-term treatment.
Lebesgue's Convergence Theorem of Complex-Valued Function
Authors: Narita Keiko , Endou Noboru , Shidama Yasunari
Published: July 2009

Lebesgue's Convergence Theorem of Complex-Valued Function

In this article, we formalized Lebesgue's Convergence theorem of complex-valued function. We proved Lebesgue's Convergence Theorem of realvalued function using the theorem of extensional real-valued function. Then applying the former theorem to real part and imaginary part of complex-valued functional sequences, we proved Lebesgue's Convergence Theorem of complex-valued function. We also defined partial sums of real-valued functional sequences and complex-valued functional sequences and showed their properties. In addition, we proved properties of complex-valued simple functions.
Probability on Finite and Discrete Set and Uniform Distribution
Authors: Okazaki Hiroyuki
Published: July 2009

Probability on Finite and Discrete Set and Uniform Distribution

A pseudorandom number generator plays an important role in practice in computer science. For example: computer simulations, cryptology, and so on. A pseudorandom number generator is an algorithm to generate a sequence of numbers that is indistinguishable from the true random number sequence. In this article, we shall formalize the "Uniform Distribution" that is the idealized set of true random number sequences. The basic idea of our formalization is due to [15].
Riemann Integral of Functions from R into Rn
Authors: Miyajima Keiichi , Shidama Yasunari
Published: July 2009

Riemann Integral of Functions from R into Rn

In this article, we define the Riemann Integral of functions from R into Rn, and prove the linearity of this operator. The presented method is based on [21].
Effects of Dietary Selenium Source and Storage on Internal Quality of Eggs
Authors: Kralik Gordana , Gajčević Zlata , Suchý Pavel , Straková Eva , Hanžek Danica
Published: July 2009

A 4-week experiment was carried out on 360 laying hens of the Hy Line Brown hybrid. Laying hens were divided into three groups (C, E1 and E2) with 120 hens in each group and kept in 24 cages. Hens were fed layer diets containing 18% of crude protein and 11.60 MJ ME. Hens in the control group C were fed diets that contained 0.2 mg/kg of inorganic selenium (sodium selenite). Experimental groups E1 and E2 were given diets with increased concentrations of selenium as follows: E1 = 0.4 mg/kg of selenium (sodium selenite), E2 = 0.4 mg/kg of organic selenium (Sel-Plex). Selenium concentration in diets affected significantly the content of selenium in albumen (P < 0.001) and yolk (P < 0.05). The highest concentration of selenium was determined in albumen and yolk of eggs produced in group E2 (345 ng/g and 783 ng/g, respectively), then in eggs of group E1 (230 ng/g and 757 ng/g, respectively), and group C had the lowest concentration of selenium in albumen and yolk (181 ng/g and 573 ng/g, respectively). After 28 days of storage at 4 °C, the eggs containing organic selenium had more freshness (VN: C = 32.9, E1 = 2.60, E2 = 2.11). It was concluded that higher concentration of organic selenium in eggs was a limiting factor in metabolic processes, which positively affected the indicators of egg freshness.
Changes in the Rate of Lipid Peroxidation in Plasma and Selected Blood Antioxidants before and during Pregnancy in Ewes
Authors: Erişir Mine , Benzer Fulya , Kandemir Fatih M.
Published: July 2009

Pregnancy is a condition that favours oxidative stress. The aim of this study was to evaluate the oxidant and antioxidant status by measuring glutathione peroxidase (GSH-Px), catalase (CAT) activities and malondialdehyde (MDA) and glutathione (GSH) concentrations before and during pregnancy in ewes. Twelve healthy female and two healthy male Awassi sheep, aged 4-5 years, weighing approximately 50 - 55 kg each, were used in the study. The ewes’ blood samples were taken before synchronization and during pregnancy (on 25th days of each month of pregnancy). Plasma MDA concentrations in the 2nd and 3rd months of pregnancy in ewes were lower than in the 1st, 4th, 5th months of pregnancy and in the non-pregnant ewes. GSH concentrations and GSH-Px activities during pregnancy were increased (P < 0.01). GSH concentrations and GSH-Px activities were the highest in the 2nd and 3rd months of pregnancy. CAT activities were decreased after the 1st month of pregnancy in ewes (P < 0.001). They were the lowest in the 2nd and 3rd months of pregnancy. The findings of our study show decreased CAT activities and elevated GSH concentrations and GSH-Px activities after the 1st month of pregnancy in ewes. These changes in the indicators under study may indicate a predisposition to oxidative stress in the 2nd and 3rd month of pregnancy in ewes.
Subchronic Oral Exposure to Prometryne Changes Relations of Blood Biochemistry Indicators in Mice
Authors: Đikić Domagoj , Benković Vesna , Horvat-Knežević Anica , Brozović Gordana , Oršolić Nada , Springer Oscar P.
Published: July 2009

Prometryne is a methylthio-s-triazine herbicide used for the control of annual broadleaf and grass weeds in many cultivated plants. Significant traces are documented in the environment, mainly waters, soil and plants used for human and domestic animal nutrition. The aim of this study was to investigate whether prometryne, administered orally, could induce changes in metabolic patterns and cause cell damage in specific organs of exposed mice. Three different doses of prometryne (185, 375, 555 mg kg-1) were given per os repeatedly every 48 h, in a subchronic in vivo experimental design. After 28 days (14 doses), the correlations between the basic blood biochemistry indicators were analyzed (LDH, GGT, AlP, creatinine, ALT, AST). The increase in GGT and decrease in creatinine were the most distinct effects. LDH and AlP were increased, but rather explicitly in different dosage groups. ALT and AST did not change significantly, indicating that liver damage was milder than expected. Significant correlations between specific enzymes in renal tissue were lost in exposed groups. The correlations between muscle tissue specific enzymes were significant as a result of prometryne toxicity. Disbalance in relations between the serum indicators under study indicates that prometryne might have a myotoxic and nephrotoxic potential and the potential to affect enzymes and molecules important in normal metabolic pathways of bioenergetic physiology.
Enterococci Isolated from Japanese Quails Exposed to Microgravity Conditions and Stability of their Properties
Authors: Lauková Andrea , Michlovičová Gabriela
Published: July 2009

Enterococci isolated from the crop and caecum of Japanese quails exposed to 7 day conditions of microgravity were re-vitalized after their dry-freezing long storage. Originally, the strains were isolated from Japanese quails after their landing from flight onboard the orbital station Mir during the experiment in August 1990. Because taxonomy as well as the studies concerning the bacteriocins, especially those produced by enterococci, have been continually developed for years, the aim of this study was to confirm species identification, stability of the properties of enterococci as well as to test new properties after their long storage. Genotyping allotted the strains to the species E. faecium. Lactic acid production was detected in similar amounts in the strains before and after their long-storage in dry-frozen form. The strains were vancomycinsensitive and kanamycin-resistant before as well as after their long-time storage. Variability in sensitivity to different antibiotics was found among the strains tested even before and after longtime storage. Each of the strains possessed at least one structural enterocin gene. The structural genes for enterocin A, P, B, L50B were detected in E. faecium EP7. E. faecium EP2, EEP4 have the genes for ent A, B, L50B. The gene for ent P was detected only in the strain EP7. The most often detected was ent A gene followed by ent genes B, L50B. All strains inhibited growth of at least 4 out of 15 indicators. The stability of the enterococcal properties determined before as well as after their dry-freezing was not influenced during their long-term storage; moreover, new properties were determined.
Titres of Specific Antibodies against Toxoplasma gondii in Goats and their Kids
Authors: Mišurová Ľubica , Svobodová Vlasta , Pavlata Leoš , Dvořák Rudolf
Published: July 2009

The aim of our study was to perform repeated determination of specific antibody levels in mothers and their kids in order to assess indirectly the possibility of vertical transmission of toxoplasmosis in goats. Twenty-eight goats with their kids were included in the study. The following variables were assessed: number of born kids in relation to antibody titres of goats; levels of specific antibodies in the blood of goats and kids; and concentrations of immunoglobulins (Ig), total protein (TP) and total globulins (G) in order to define the end of colostral immunity and the start of active production of antibodies in kids under 69 days of age. Specific antibodies against Toxoplasma gondii in goats were detected by IFAT in titres ranging from 0 to 1 280. Out of a total of 28 animals, 5 goats were negative (17.9%) and 23 goats were seropositive (82.1%). The goats delivered 42 kids. A total ratio of number of kids to number of mothers was 1.5. Partial evaluation of results in goats without positive titre against T. gondii before parturition and goats with positive titre showed that negative goats tended to have more kids (p < 0.1) (ratio 1.80) compared to positive goats (ratio 1.35). A significant decrease in levels of TP, Ig and G was observed between days 27 and 41. Samples taken on days 55 and 69 proved gradual increase of active production of antibody response, which was supported also by a significant increase (p < 0.01) of monitored non-specific immunity indicators. During this period, we observed increased titres of specific antibodies against toxoplasmosis in 20 kids (5 kids 41 days old, 5 kids 55 days old, and 10 kids 69 days old) and thus we could assume the possibility of vertical transmission of toxoplasmosis.
Effect of Leptin Gene Polymorphism on Fattening and Slaughter Value of Line 990 Gilts
Authors: Stępień-Poleszak Dorota , Pietruszka Arkadiusz , Kawęcka Maria
Published: July 2009

The study was aimed at defining leptin gene polymorphism and its potential association with values of particular features of fattening and slaughter value of gilts of Line 990. The study included a total of 208 gilts. The polymorphic locus in LEP gene was identified by the restriction enzyme HinfI in 3469 position, by using the polymerase chain reaction-restriction fragment-length polymorphism (PCR–RFLP) method. Two alleles of LEP gene were identified: T (0.94) and C (0.06), resulting in two genotypes: TC (0.12) and TT (0.88). We did not observe any gilts of CC genotype. The analysis of values of fattening and slaughter features, depending on LEP genotype did not reveal significant differences in body mass increase, daily gain from day 63 to 180, and daily gain from birth to day 180, feed conversion per 1 kg body mass and the loin-eye thickness. Significant differences between the LEP genotypes were present for such features as the backfat thickness at points P2 (p ⪬ 0.05) and P4 (p ⪬ 0.01) and average backfat thickness (p ⪬ 0.01) in favour of TT genotype. We noted higher average values of lean meat content in carcass in favour of TT homozygotes, compared to the heterozygotes (p ⪬ 0.05). The investigation contributes additonal information regarding LEP gene polymorphism in gilts of Line 990. Knowledge of LEP genotypes may be useful to improve the slaughter value in gilts primarily due to less fatness. Due to the lack of individuals representing CC genotype in our results, research should continue on a larger population.
Gastrointestinal Stromal Tumour in a Guinea Pig: a Case Report
Authors: Jelínek František , Hron Pavel , Hozmanová Františka
Published: July 2009

The objective of this contribution was to present a case report of gastrointestinal stromal tumour (GIST) in one guinea pig: a pet animal, male, 3.5 year of age, tricolour. Approximately for five weeks before death wasting, in spite of good appetite, decreased locomotor activity, soft and malodorous faeces were observed by the owner. The animal spontaneously died and at necropsy a grey-pink coloured tumour of walnut size located in the terminal segment of the ileum was observed. A solid malignant tumour of mesenchymal appearance was diagnosed histologically. One part of the sample consisted of tightly packed spindle cells arranged in interlacing fascicles, in the other part epithelioid cells predominated with slightly myxoid intercellular matrix. Lymphocytic sheaths were observed around some blood capillaries. Immunohistochemistry revealed positivity for actin, CD 117, neuron-specific enolase, glial fibrillary acidic protein, and p53 protein; however, desmin, S100 protein and synaptophysin were negative. On the basis of histological and immunohistochemical examinations GIST was diagnosed.
Comparison of Preventive and Therapeutic Transplantations of Allogeneic Mesenchymal Stem Cells in Healing of the Distal Femoral Growth Plate Cartilage Defects in Miniature Pigs
Authors: Plánka Ladislav , Starý David , Hlučilová Jana , Klíma Jiří , Jančář Josef , Křen Leoš , Lorenzová Jana , Urbanová Lucie , Crha Michal , Srnec Robert , Dvořák Milan , Gál Petr , Nečas Alois
Published: July 2009

The aim of the study was to verify whether there is a difference in the lengthwise growth of the femurs and in their angular deformity when comparing preventive vs. therapeutic transplantation of allogeneic mesenchymal stem cells (MSCs) to an iatrogenic defect in the distal physis of femur. Modified composite chitosan/collagen type I scaffold with MSCs was transplanted to an iatrogenically created defect of the growth cartilage in the lateral condyle of the left femur in 20 miniature male pigs. In Group A of animals (n = 10) allogeneic MSCs were transplanted immediately after creating the defect in the distal physis of femur (preventive transplantation). In Group B of animals (n = 10) the same defect of the growth cartilage was treated by transplantation of allogeneic MSCs four weeks after its creation (therapeutic transplantation), after the excision of the bone bridge that had formed in it. On average, left femurs with a damaged distal physis and preventively transplanted allogeneic MSCs (Group A) grew during 4 months from transplantation by 0.56 ± 0.44 cm more than right femurs without the transplantation of MSCs, whereas left femurs with physeal defects treated with a therapeutic transplantation of allogeneic MSCs (Group B) by 0.14 ± 0.72 cm only, compared to right femurs without transplanted MSCs. Four months after preventive transplantation of MSCs (Group A), valgus deformity of the distal part of left femur with the defect was 0.78 ± 0.82°; in the control group (right femur in the same animal without MSCs transplantation) it was 3.7 ± 0.82°. After therapeutic transplantation of MSCs (Group B) 0.6 ± 3.4°, in the control group (right femur in the same animal without MSCs transplantation) it was 2.1 ± 2.9°. In all the animals of Groups A and B, the presence of newly formed hyaline cartilage was confirmed histologically and immunohistochemically. In the distal physis of right femurs with an iatrogenic defect of the growth cartilage without the transplantation of MSCs (control) bone bridge was formed. Preventive transplantation of allogeneic MSCs into the defect of the distal growth zone of femur appears more suitable compared to the therapeutic transplantation, with regard to the more pronounced lengthwise bone growth. Differences found in the extent of valgus deformity were non-significant comparing preventive and therapeutic transplantations of MSCs.
Preconditioning as a Possible Protective Mechanism in the Spinal Cord Ischemia
Authors: Radoňak Jozef , Čížková Dáša , Lukáčová Nadežda , Kluchová Darina , Ostró Alexander , Gálik Ján
Published: July 2009

The present study deals with the problem of spinal cord protection. The aim of this study was to simulate conditions during surgery on aortic aneurysm and to consider their possible utilisation in clinical practice. Wistar albino rats of both sexes were used in the experiment. Surgery was performed on the thoracic part of aorta. The closure of aorta in duration of 12 min caused a neurological deficit in 81% of rats, 14 min of ischemia paralysed 90% of animals. Preconditioning with 3-min ischemia following 30 min recirculation improved the neurological score in the group with 12 min of ischemia after 48 h, in which only 27% of rats were paralysed. The same preconditioning was performed in the group of animals with 14 min of ischemia, and as a consequence, 33% of rats were paralysed in that group. Protection of the spinal cord during ischemia can be achieved by preconditioning. Thus the method of preconditioning appears to be a prospective technique for the improvement of the devastating neurological deficit after surgery on the aorta and has provided optimism that additional therapies will be possible in the future.
Influence of Propylparaben on Vitellogenesis and Sex Ratio in Juvenile Zebrafish (Danio rerio)
Authors: Mikula Přemysl , Kružíková Kamila , Dobšíková Radka , Haruštiaková Danka , Svobodová Zdeňka
Published: July 2009

The aim of the study was to evaluate the xeno-oestrogenic potential of propylparaben in vivo using zebrafish (Danio rerio). Experimental juvenile zebrafish (20 days post hatching) were fed a feed containing 500, 1000, or 2000 mg kg-1 of propylparaben, fish in a positive control group were given a feed treated with 20 mg kg-1 of 17β-oestradiol, and the control fish were given the feed free of either tested substance. The exposure of fish to propylparaben did not affect vitellogenesis after 20 days exposure but seemed to influence the sex differentiation processes, as evidenced by a sex ratio significantly skewed towards females in the group fed 500 mg kg-1 of propylparaben following 45 days of exposure. The potential of the fish to respond to oestrogenic stimulation was confirmed, since significantly higher vitellogenin concentrations were detected in the fish from the positive control group.
Pheno- and Genotyping of Staphylococcus aureus Isolates of Sheep Origin
Authors: Mašlanková Jana , Pilipčincová Ivana , Tkáčiková Ľudmila
Published: July 2009

The aim of the study was to determine the prevalence of genes encoding virulence factors in Staphylococcus aureus strains isolated from raw sheep milk, sheep cheese and Bryndza cheese. Genes encoding staphylococcal enterotoxin (sea, seb, sec, sed and see), toxic shock syndrome toxin-1 (tst), exfoliative toxins (eta and etb) and collagen-binding protein (cna) were detected. In a total of 79 S. aureus isolates all assessed toxins encoding genes were found, except for see, eta and etb. Overall, 75.9% of S. aureus isolates were found to be positive for one or more toxin genes. The sec gene was found most frequently (24.1%), followed by tst (22.8%), seb (13.9%), sed (10.1%) and sea (5.1%). The cna gene was detected in 55.7% of S. aureus isolates. Based on tandem repeats in coa gene, five coa types were observed, further divided into 16 subtypes based on their RFLP pattern. Similarly tandem repeats in spa gene divided S. aureus isolates into 7 types. In the parallel antibiotic resistance study, 69.6% isolates were resistant to at least one of the 11 tested antibiotics. The pheno- and genotyping of S. aureus isolates of sheep origin presented in this work update the epidemiological data in Slovakia.
Factors Affecting the Content of Ergosterol and Zearalenone in Selected Grass Species at the End of the Growing Season
Authors: Skládanka Jiří , Dohnal Vlastimil , Doležal Petr , Ježková Alena , Zeman Ladislav
Published: July 2009

The objective of the study was to assess the safety of forage prepared from selected grass species by means of the analysis of ergosterol and zearalenone. Graminaceous plants studied at the end of their growing season were Festulolium, Dactylis glomerata and Arrhenatherum elatius. Other indicators assessed were the content of ergosterol and zearalenone during the autumn and the intensity of grassland use in the summer season as related to the studied contents of metabolites. Grasslands were harvested either in October, November or December. The secondary metabolites were analyzed by means of high performance liquid chromatography. At the end of the growing season, the ergosterol content was the lowest in the Festulolium forage (110.04 mg kg-1), the highest contents were observed in the Dactylis glomerata and Arrhenatherum elatius forages (145.73 mg kg-1 and 139.55 mg kg-1, respectively). The safety of Festulolium was also corroborated by the low zearalenone content (0.357 mg kg-1). On the other hand, the high ergosterol content in Arrhenatherum elatius was combined with a high content of zearalenone (1.554 mg kg-1). Although Dactylis glomerata exhibited an ergosterol content comparable with that of Arrhenatherum elatius forage, its zearalenone content was comparable to the Festulolium forage. Among the three species under study we found a significant difference (P < 0.01) in the ergosterol and zearalenone contents. Changes in the ergosterol and zearalenone contents were also apparent from October to December. The highest (P < 0.01) content of ergosterol was found in December (254.26 mg kg-1). The higher (P < 0.01) zearalenone content in this month (1.588 mg kg-1) was caused by the Arrhenatherum elatius forage. Moreover, the contents of ergosterol and zearalenone were affected (P < 0.01) also by the number of cuts in summer. The higher ergosterol content indicated a higher forage infestation by fungi and the inherent risk of the occurrence of mycotoxins. However, the high ergosterol content not always correlated with the high content of zearalenone. When cattle is grazing in winter, a higher occurrence of mycotoxins in the feed may be expected and the related damage to animal metabolism may increase the number of diseased animals with consequent impact on animal production, performance and health and animal husbandry economics.
Creep properties from indentation tests by analytical and numerical techniques
Authors: Galli Matteo , Oyen Michelle L.
Published: July 2009

Analytical and numerical methods for the identification of creep properties of two polymers and indium from indentation tests are compared. Creep indentation experiments are performed at fixed peak force following ramp loading. The experiments are modeled both by analytical techniques and by finite elements and the models are integrated in an identification routine. The assumed mechanical behavior allows for a satisfactory fit of the experimental data. For the considered viscoelastic materials analytical and numerical modeling are equivalent whereas for indium finite element modeling is to be preferred since the analytical model is not representative at the large levels of plastic strain experimentally obtained.
Analysis of nanoindentation and nanoscratch experiments of thin amorphous carbon coatings and multilayers: friction, wear and elastic – plastic deformation
Authors: Paulkowski Dominik , Schiffmann Kirsten
Published: July 2009

The determination of mechanical properties of thin films is of crucial interest for applications of protective layers. Nanoindentation and nanoscratch experiments of diamond-like carbon coated (100) silicon surfaces under ambient conditions have been performed with a conical indenter on a Hysitron system, mounted on an atomic force microscope system. Single layers and multilayers with hard soft stacking were tested as well. Microhardness, friction and wear behaviour were determined with multi-indentations, single scratches and oscillating multicycles scratch. The indentation experiments revealed that critical force plastic deformation takes place. The oscillating multicycles scratch experiments determined the high wear resistance of the diamond-like carbon coatings. Multilayer systems were compared with single layer coatings.
Nanoindentation of pseudoelastic NiTi shape memory alloys: Thermomechanical and microstructural aspects
Authors: Pfetzing Janine , Schaefer Andreas , Somsen Christoph , Wagner Martin F.-X.
Published: July 2009

Nanoindentation allows local characterization of the microstructural processes associated with pseudoelastic recovery in NiTi shape memory alloys. We discuss nanoindentation and tensile testing results, both carried out at different temperatures on a NiTi alloy with three different microstructures (containing no, small and large Ni-rich precipitates). Maximum shape recovery in indentation experiments and during tensile testing occurs in microstructures with fine precipitates. Thermomechanical constraints affect pseudoelasticity differently in micro- and macro-scale testing: Indentation at temperatures as close as possible to the transformation start temperatures is associated with better shape recovery than testing at higher temperatures, whereas maximum shape recovery is only observed at slightly higher temperatures in macroscopic testing. These results are rationalized by considering the effect of temperature on stress-induced martensitic transformation and dislocation plasticity.
Effect of indenter shapes on inverse materials characterization based on the dual indenters method
Authors: Kong Xiaohang , Shi Yanguo , Li Bing , Rothwell Glynn , English Russell , Yang Qingxiang , Ren Xuejun
Published: July 2009

The indentation method is a useful tool for studying the onset of plastic flow and work hardening in small volumes. Several approaches based on either single and dual indenters have been reported to characterise a wide range of materials. In this work, the single and dual indenters approaches, with different indenter types, have been comparatively studied using an inverse finite element modelling program developed based on the Kalman filter method. The effect of indenter shapes on the accuracy and uniqueness of the predicted results, as well as convergence time of the program are systematically analysed by automatically mapping the results with a wide range of initial values.
Friction and adhesion of carbon nanotube brushes
Authors: Jarzabek Dariusz , Rymuza Zygmunt , Ohmae Nobuo
Published: July 2009

Brushes made of carbon nanotubes have been tested by use of atomic force microscopy. Two different cantilevers were used: a silicon cantilever with a spherical tip made of SiO2 and a beryllium bronze cantilever with a tip made of steel. Sliding in the lateral direction was studied to measure the friction coefficient and to examine nanotribological properties. Nanoindentation was used to measure the pull-off force. Finally, a model of adhesion was created and experimental results were compared with it.
UFG and nanocrystalline microstructures produced by hydrostatic extrusion of multifilament wires
Authors: Pachla Wacek , Kulczyk Mariusz , Mazur Andrzej , Sus-Ryszkowska Malgorzata
Published: July 2009

Aluminium, Al-4Cu-0.5Mg-1Mn aluminium alloy (AA2017), copper, iron and nickel in the form of a bundle of wires placed in appropriate capsules were subjected to cumulative hydrostatic extrusion to form 3 mm wires with total true strain above 10 in Al, the aluminium alloy and Cu and above 7 in Ni and Fe. The deformation was first induced in single wires which were then assembled and further deformed to form a multifilament wire. The final product had a nanocrystalline (grain size below 100 nm in Fe and the 2017 Al alloy) and ultra-fine grain (below 130 nm in Ni and below 270 nm in Cu and Al) microstructure. The grain refinement resulted in the microhardness being increased, with the greatest increase to 3.5 GPa being achieved in iron. During hydrostatic extrusion, the severe deformation was possible due to the high applied pressures of up to 1.7 GPa. The hydrostatic extrusion of multifilament wires broadens the application range of this process extending it to the fabrication of ultra-fine grain and nanocrystalline microstructures.
2,4‐Dicyano‐3‐diethylamino‐9,9‐diethylfluorene Based Blue Light‐emitting Star‐shaped Compounds: Synthesis and Properties
Authors: CHEN Xiaohang , CHEN Xiaopeng , ZHAO Zujin , LÜ Ping , WANG Yanguang
Published: July 2009

Two new star‐shaped molecules 1 and 2 containing a triphenylamine/benzene moiety as the central core and three 2,4‐dicyano‐3‐diethylamino‐9,9‐diethylfluorene moieties as the peripheral functional groups were synthesized and characterized. Charge transfer properties for these compounds were observed in photophysical experiments due to their D‐A molecular structure. Compound 1 presented dual fluorescence in high polar solvents. Moreover, these compounds exhibited moderate fluorescence and high thermal stabilities, indicating their potential application to blue light emitting materials.