bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation and Optimization of Low-Density Cement: Laboratory Studies and Field Applications
Authors: Al-Yami A. S. , Nasr-El-Din H. A. , Al-Arfaj M. K. , Al-Saleh S. H. , Al-Humaidi A. S. , Al-Shuker N. A.
Published: March 2008

Cementing a string in one stage is a challenging task, especially in the presence of weak formations. Cement slurry losses during placement is highly possible if the equivalent circulating density (ECD) exceeds 82 pcf during placement. A conventional method to overcome this challenge is to use multi-stage cementing by setting the stage tool above the loss circulation zone. However, field data indicate that the tool can fail, thus causing serious delay and economic loss. In addition, stage tools are considered weak point and not good for long term seal. A second method for zonal isolation is to use low density cement. In this study, we considered cementing the intermediate and production casings in S-1 (sandstone) and S-2 (carbonate) shallow formations and BJD (dolomite) deep formation in a single stage using lower density cement based on hollow microspheres at 70 pcf. The shallow conditions simulated in the lab tests were 150 °F curing temperature, 2,400 psi conditioning pressure and 1,800 psi confining pressure for 3 months. The deep conditions were 260 °F curing temperature, 5,000 psi conditioning pressure and 3,000 psi confining pressure; also for 3 months.

Hollow microspheres cement was used in oil and gas wells without encountering any operational problems. However, the high cost of microspheres cement was a limitation for potential field applications. In this study, we present extensive lab work to optimize hollow microspheres low density cement (LDC) by elimination of micro fine cement from the blend. Experimental studies (shrinkage, compressive strength, porosity, gas and brine permeability, and chemical analysis cement) were conducted to determine the effect of this optimization on the properties of cement. The testing was performed in Saudi Aramco facilities to reduce the cost of hollow microspheres systems.

Data generated during three months supported the use of the optimized system to cement casings at the shallow conditions tested. The removal of micro fine cement did not reduce the compressive strength with an average of 2,013psi; neither shrinkage nor liquid permeability was observed during the three months of testing. The use of the optimized system will help to bring cement to surface in one stage. The optimized blend price is 40% less than conventional hollow microspheres low density cement.

This paper will discuss case histories that include job design, execution, and evaluation of the LDC. Field treatments were conducted without encountering any operational problems. The treatment was successful and maintained isolation for more than three years.
Design of an ASP Pilot for the Mangala Field: Laboratory Evaluations and Simulation Studies
Authors: Pandey Amitabh , Beliveau Dennis , Corbishley Douglas W. , Kumar M Suresh
Published: March 2008

Mangala is the largest discovered oil field in the Barmer Basin of Rajasthan, India having a STOIIP of over 1 billion barrels in multiple stacked fluvial clastic reservoirs. It contains medium gravity (20-28°API), waxy, viscous crude (9-17 cp) in high permeability (1-25 Darcy) clean sandstone reservoirs. Initial development plans for the field are based on waterflooding, with at least the initial volumes of water heated to minimize any issues with wax dropout in the reservoir. Owing to the relatively high oil viscosity and adverse mobility displacement for waterflooding, the desirability of implementing an appropriate EOR process was identified shortly after the field discovery. Screening studies identified aqueous-based chemical flooding processes as the most favorable for Mangala.

Detailed laboratory studies have now identified the potential of alkaline-surfactant-polymer (ASP) processes in significantly improving the sweep and displacement efficiency. The laboratory studies involved screening and optimization of the ASP slug formulation based on IFT measurements, adsorption measurements, polymer rheological and thermal stability studies; followed by a series of linear and radial corefloods. Experiments indicate the ASP process is the most effective chemical EOR process for Mangala, with improvement in recovery efficiency above the waterflood recovery of over 30% STOIIP.

Chemical EOR simulations with STARSTM have been used extensively to understand the process mechanisms via matching of the coreflood experiments. Simulation parameters tuned to the laboratory data were used to evaluate the process performance under field conditions. A closely spaced five-spot pilot with 100m well spacing has been designed to evaluate the process. The pilot consists of four injectors, the central producer, three saturation monitoring wells and two post-pilot core holes. An ASP pilot will be implemented in the field shortly after startup of the waterflood.
High-Speed Wired Drillstring Telemetry Network Delivers Increased Safety, Efficiency, Reliability and Productivity to the Drilling Industry
Authors: Hernandez M. , MacNeill D. , Reeves M. , Kirkwood A. , Lemke S. , Ruszka J. , Zaeper R.
Published: March 2008

High-speed wired drill strings enable two way wireline communications between drilling and evaluation service provider's bottom-hole-assemblies (BHA) and surface systems. Compared to even the most advanced mud pulse telemetry, this new capability allows reliable communication with Rotary Steerable Systems (RSS), Measurement While Drilling (MWD) systems and Logging While Drilling (LWD) systems at data rates tens of thousands of times faster than ever before.

This paper describes the system development and discusses in detail the advantages immediately attainable when complete, memory quality, drilling and evaluation data is provided instantaneously at surface while drilling. These advantages include:

increased safety by continuous downhole pressure, drill string dynamics and high rate drill string energy transmission data monitoring regardless of flow or rig state; increased efficiency by optimizing RSS and bit performance, reducing hidden NPT, and monitoring wellbore conditions while drilling; increase reliability by providing a redundant telemetry system and enabling the user to identify damaging drill string dynamics; maximized productivity from more accurate wellbore placement.

The paper will then further discuss how application of the system may further develop to maximize the value in accessing memory quality LWD data instantaneously via the wired pipe network while drilling.
Talent Retention in Multinational Coming to India: A Fresher's Perspective
Authors: Chatterjee Soubhik
Published: March 2008

Now that it has been accepted all over the world, that India is the current seat of world class talent, that is available in great numbers and at a fraction of the cost of that of western countries, major international oil companies are pouring in to hire young Indian engineering graduates. To be in the race, even the national oil companies are striving hard to make their offers more lucrative for the young and ambitious Indian graduate. The real problem, however, lies not in attracting talent but to retain them. Indian graduates, especially from top tier institutes such as the Indian Institutes of Technology or Regional Engineering colleges, have a proven record of being highly opportunistic and ambitious. As such, they always on a look for a more challenging, more lucrative and faster paced career. The companies hiring them should, therefore, ensure that, during the initial few years, they adopt specific strategies to retain this vast skill pool. The author, a fresh graduate and into a major oil company, analyses the situation from an insider's perspective and offers some solutions for the same.
Interference Testing: A Significant Part of the Mangala Appraisal and Reservoir Characterization Programs
Authors: Tandon Rohit , Beliveau Dennis
Published: March 2008

Mangala is currently the largest discovered oil field in the Barmer Basin of Rajasthan, India, with a STOIIP of over 1 billion barrels contained in the stacked clastic fluvial reservoirs of the Fatehgarh Group. The field was discovered in January 2004 and a fast-track appraisal program followed, involving the drilling of eight more wells and a host of data acquisition activities in 2004-2007. Production startup under waterflood is planned for 2009, with an initial plateau production rate of ~100,000 bopd. As there is no analog Fatehgarh production anywhere else in the country, multi-well and single-well interference tests provided essential large-scale areal and vertical reservoir connectivity data that helped to ground the geologic and reservoir models that were the basis of the field development plan.

Areal interference tests were conducted by recording a baseline MDT pressure trace throughout the entire reservoir section in the observation wells. After production/injection began in the source well, additional MDTs were conducted in the observation wells to monitor pressure changes throughout the reservoir section, thus providing both an areal and a vertical measurement as to how the pressure response spread. An important test was carried out by producing Mangala-1 and monitoring pressure responses in three adjacent wells that were 300 - 1,500m distant. This test demonstrated excellent areal communication and a fair degree of vertical communication through the reservoir.

A second key areal interference test was carried out in conjunction with a water injectivity test in Mangala-2 while observing the pressure response in Mangala-1 and Mangala-4. Although a response was observed in Mangala-1 at a distance of 2,700m, no response was observed 700m away in Mangala-4, confirming that the shale correlated between Mangala-2 and Mangala-4 is a barrier to fluid flow. Finally, a single-well vertical interference test was carried out in Mangala-5; this demonstrated that a typical shale layer that occurred between the producing and observation zones in the well was actually of limited areal extent, and provided a "match point" for the geologic model.

This paper explains the design, operations and results interpreted from each test and how these results were key factors in geological modeling of the field and planning the initial development concept.
Magnetic Shielding During MWD Azimuth Measurements and Wellbore Positioning
Authors: Amundsen P. A. , Ding S. , Datta B. K. , Torkildsen T. , Saasen A.
Published: March 2008

Magnetic contamination of the drilling fluid may contribute significantly to errors in directional surveying of wellbores. Such contaminations shields the field measured by the magnetic sensors in MWD directional tools. The resulting error often exceeds typical sensor uncertainties, and so the accuracy of the inferred wellbore position is severely degraded. Although the magnetic interference can be reduced by careful attention to procedures for transport, pumping and handling of drilling fluids and their associated additives, the problem has not yet been eliminated.

In order to understand the magnetic shielding effect in a well-defined setting, we have initiated a series of laboratory measurements, where magnetic material of known properties are added to a well defined non-magnetic drilling fluid, and measuring the resulting magnetic shielding with a fluxgate magnetometer immersed in the fluid.

In our experiments, powdered magnetite was added to a mixture of xanthan gum in water to obtain a mixture of nominal magnetic susceptibility typical of drilling fluids containing metal from pipe wear and erosion. Immediately after stirring, the vertical component of the Earth's magnetic field inside the liquid was measured and found to be significantly damped. Without touching the system, the field was subsequently logged. It was found to continue to decay for the next hour, or so, reaching a fairly sharp minimum. The magnetic field then started to increase slowly and irregularly again over the next few days. The observed effect, combined with analysis of directional data, can explain errors encountered in directional surveying.
Analyzing Geomechanical Effects while Drilling Sub Salt Wells through Numerical Modeling
Authors: Mackay F. , Inoue N. , da Fontoura S. A. B. , Botelho F.
Published: March 2008

Santos Basin is one of the most promising basins of Brazil, recently it was discovered light crude oil of 30° API (American Petroleum Institute), this reservoir of high productivity is located below a salt layer of two thousand meters (6561,7 ft) of thickness. Salt also known as an evaporite rock is found in many hydrocarbon basins around the world. Evaporites are sediments formed initially from minerals dissolved in water, the most common are: halite, gypsum, and anhydrite. These minerals are found in areas that passed by a geological time of high evaporation or precipitation. Evaporites in general have the structure of a dome, formed when a thick layer of salt found in the bottom begins to crossover superior layers vertically; this process takes millions of years. The presence of saline structures takes into favorable conditions for creating a trap for hydrocarbons, increasing the success of probability in oil and gas exploration. In salt drilling the main problem is the closing of the well or known as squeeze or salt pinch, this phenomenon provokes the imprisonment of the drillstring also known as stuck pipe. Evaporite rock behavior is defined through a creep model. The creep model is the term used in the bibliography to define the tendency that a material has to move or to deform permanently to relieve stresses. Strains take place due to extended levels of stress; this stress is less than the rupture stress. In this matter it was chosen a numeric tool to simulate the behavior of salt drilling and the effects that this will have due to the overburden stress and drilling fluid pressure. This tool is a commercial program of finite elements in 3D (three dimensions). The objective of this work is to determine the effect of the fluency (creep) in salt during and after the drilling of the well, through numeric simulation. At first it is shown a validation of the commercial finite element program comparing results from literature and then it is shown a simulation of a 3D vertical salt wellbore.
Highly Flexible Mud-Pulse Telemetry: A New System
Authors: Klotz C , Wassermann I , Hahn D
Published: March 2008

Mud Pulse Telemetry (MPT) systems enable the MWD/LWD companies to transmit to surface valuable directional and formation data during the drilling process. This data is used to optimize the drilling process, making drilling operations more cost efficient and allowing the drilling of more complex wells.

The major factors limiting MPT data rates include maximum downhole signal strength, signal attenuation, surface induced noise and surface piping induced signal reflections. Most of these are not predictable, not arbitrarily adjustable and potentially change their properties during the course of data transmission. To achieve maximum possible data rates under those challenges, telemetry systems must be highly flexible, both downhole and at the surface receiver. Downhole, the transmission tool should be able to support different signal types and different signal frequencies to optimally use the transmission channel (the mud filled pipe bore).These signaling parameters should be changeable during operation. On surface, sophisticated noise processing should be employed to increase the overall system Signal-to-Noise Ratio (SNR).

This paper describes a new system for mud pulse telemetry that supports two signaling types, different signal modulations and various signal frequencies. The new system comprises a novel mud pulser and a digitally controlled, automatically adjusted surface system. With the downhole mud pulser in the borehole, the new system allows the optimization of the mud pulse telemetry process for maximum MWD/LWD information at surface while drilling the well.

This paper introduces the system and gives details on how the achieved high speed data rates of the new telemetry system have helped to deliver real time answers while drilling.
New Generation Rotary Steerable System and Pressure While Drilling Tool Extends the Benefits of Managed Pressure Drilling in the Gulf of Mexico
Authors: Njoku Johnson Chydi , Husser Alex , Clyde Robert
Published: March 2008

As hydrocarbon basins mature, reservoir pressure depletion caused by hydrocarbon production leads to severe pore pressure/fracture gradient anomalies that can reduce an otherwise sufficient mud weight window significantly. At the same time, reentries involving slim-hole sidetracks incur high annular losses that further widen the gap between equivalent static and circulating densities - ESD and ECD. In this situation, it is not possible to drill using normal overbalanced methods. The risk of formation fracturing and fluid losses, fluid influxes, and wellbore collapse would far outweigh the reward of increased production. The effective variation of static and circulating densities must be minimized. A major project in the Gulf of Mexico posed such a problem. Managed pressure drilling (MPD) was adopted as the solution to manage a tight hydraulic window and effectively drill reservoirs which would have been extremely challenging using conventional drilling methods.

Traditional directional drilling with a positive displacement motor would normally create more pressure balance complications under a MPD environment due to the continuous fluctuations to the ECD when the motor is in sliding or steering mode.

This paper outlines how new generation rotary steerable systems coupled with the interpretation from a downhole real time pressure while drilling sensor was engineered to maximize drilling performance for a directionally drilled well in MPD environment.

This paper will also discuss the case histories and lessons learned and thoroughly review the range of opportunities these technologies have created in the maturing areas of the Gulf of Mexico.
Cased-Hole Sonic Technique for Stress Determination and Optimization of Oriented Hydraulic Fracturing Operations
Authors: Klimentos T. , Ghosh A. , Sagar R. , Nayak J. P. , Hotta A. , Jantasuwanna P. , Singh R. N
Published: March 2008

Shear-wave anisotropy gives a measure of stress anisotropy intensity and the associated fast-shear azimuth gives the maximum horizontal stress direction. This information is very useful in optimizing oriented hydraulic fracturing operations, wellbore stability, sand management, well placement and other applications.

In open holes, this fracture or stress induced anisotropy can be effectively measured using cross-dipole sonic logging.

However, determining shear-wave anisotropy in cased holes has been hindered by two factors. The first is the concern of the effect of casing and cement on the cross-dipole measurement, and the second is the lack of an effective device to measure the tool's orientation inside casing.

This paper presents a solution to this problem using recently developed sonic logging technology in conjunction with Gyro data acquisition.

Cased-hole Sonic and Gyro data were acquired in four wells for oriented fracturing optimization over zones with no or poor production. Gyro data was used as a reference for the sonic waveform rotation in order to determine the fast shear azimuth direction and maximum horizontal stress orientation. The cased-hole sonic monopole and dipole data quality was excellent, even over double casing sections. It was found that the reservoir sands are anisotropic; however, the shear-wave anisotropy magnitude is low.

This is the first ever cased-hole Sonic + Gyro acquisition survey in India. The results showed that we can now confidently determine shear-wave anisotropy behind casing with the new sonic technology, even in low anisotropic formations with accuracy down to ~1%.

The Sonic derived horizontal stress information was then used effectively to optimize the oriented fracturing operations. Low tortuosity while fracturing in the studied wells proved perfect direction for oriented fracturing. After fracturing, the production gain was substantial.

Therefore, such cased-hole sonic technique can be useful in generating stress-maps of the reservoirs, which can then be used in various applications, such as oriented fracturing, sand control, reservoir characterization, fracture evaluation behind casing, wellbore stability and well placement.
Utilizing Remote Collaboration and Visualization Technologies in a Collaborative Work Environment to Connect Indian Experts With Worldwide Operations
Authors: James Simon , Gullhav David
Published: March 2008

In a world where oil & gas technical expertise is in increasingly short supply companies which can tap pools of centrally located experts, to remotely and proactively support their distributed asset portfolio, will gain competitive advantage. Making maximum use of a diminishing technical skillpool is critical to ensuring sufficient expertise in assets where the workforce can not always include all the necessary specializations.

Shell Technology India plan to utilize advanced remote collaboration and visualization technologies as an enabler for ensuring connectivity between our Technology Centre in Bangalore and our operations globally, both upstream and downstream. These technologies will be housed in a purpose built Collaborative Work Environment, unique in India, which is linked to a network of such environments in our assets and other Technical centres worldwide. This close connectivity, with Shell Technology India forming part of a "virtual" asset team, is allowing us to develop new business models involving redistribution of key operational and project-based tasks to Bangalore.

The Collaborative Work Environment allows us to view real-time operational data from our worldwide production; drilling; refining and manufacturing operations, in surveillance rooms in Bangalore. Subject Matter Experts in Bangalore can then offer technical advice directly to asset teams during operational activities. Other functionality includes virtual reality viewing of subsurface & facilities 3D models, and "information walls" where multiple sources of information can be displayed simultaneously to support multidisciplinary decision-making.

Future developments are planned to include the offering of 24/7 Operational Support Services to assets in areas such as ensuring the availability of the technical infrastructure (communication networks, real-time data management systems), or routine surveillance tasks. Also "bringing operational work experience to Bangalore" by offer state-of-the-art experiential training in drilling, facilities and process control.
Cleat Characterization in CBM wells for completion Optimization
Authors: Ali Mohammad , Sarkar Arpana , Sagar Rajiv , Klimentos Theodore , Basu Indrajit
Published: March 2008

Fracture systems comprise the primary flow path within coal bed methane (CBM) reservoirs. These fractures, also called as cleats, define the reservoir character and fluid flow potential. Cleats are commonly mutually orthogonal and occur perpendicular or at very high angles to the bedding. The standard suites of logs, such as density/neutron, gamma ray and resistivity, define some of the petrophysical properties of the coal layers, but the nature and extent of cleating often remains poorly defined from these logs and by using standard log evaluation methods.

A CBM well may often penetrate multiple reservoir zones (seams) and properly characterizing the cleats will help in determining which of these seams should be completed to optimize the production. In addition, through better seam characterization, a technical basis for a preferred completion method (horizontal well, hydraulic fracture, open hole or cavity) can be ascertained.

High cleat density in coal seams is an essential requirement for better fluid flow in CBM reservoirs. The primary cleat direction and its relation with the in-situ horizontal stress directions define the fluid flow potential through the cleats and such information can be used to select the completion method.

In this study, full waveform sonic log with monopole and flexural waveform and high resolution electrical image log data from CBM wells in Jharkhand, India, have been integrated, in a bid to identify the ideal candidates for completion. Coal seams for best production potential are identified through cleat density characterization. In this paper, we show how compressional and shear slowness variation and Stoneley waveform transmission coefficient analysis are used to interpret the variation in cleat density. The cleat density is further validated from the fracture analysis using micro-resistivity image logs.

Cleat orientation can be determined from the detailed structural evaluation of the fractures seen in the high resolution resistivity image. Maximum horizontal stress direction has been computed from acoustic anisotropy evaluation. This maximum stress direction and cleat orientation have been integrated to identify seams that will have better deliverability of fluids.

In this paper we provide a guideline for selecting a completion methodology in coal bed methane wells based on cleat density, stress direction, cleat orientation and wellbore stability.
Systematic Diagnostics and Real Time Reservoir Monitoring in a High GOR Horizontal Well To Detect the Source of Gas: A Case Study in Panna Field, Western Offshore, India
Authors: Mishra Gaurav , Prakash Swaminathan , Prakash Roshan
Published: March 2008

The Panna field, located offshore the western coast of India is a carbonate reservoir with a thin oil rim (~20m) sandwiched between a gas cap and a large bottom aquifer. The field comprises of two main layers – ‘A’ zone gas cap and ‘B’ zone which is the main oil producer, separated by an interface. As the vertical/horizontal permeability ratio is high (~1) this reservoir is highly susceptible to coning problems. Horizontal multilateral wells were drilled in ‘B’ zone to achieve maximum reservoir contact with minimized gas coning. These wells are equipped with permanent downhole gauge to monitor conditions downhole in real time and auto gas lift to use energy from the gas cap to lift fluids from the oil reservoir when required in future. However, in first such well unwanted high gas production raised doubt on the completion integrity and on the possible communication between two zones. This necessitated a thorough troubleshooting to detect the gas source for corrective action afterwards.

This case study presents the methodology applied in detecting the source of the abnormal high gas production using Production Logs & Permanent down hole gauge using auto gas lift diagnostics. The diagnosis, carried out in phases, enabled us to pinpoint a highly unlikely source by removing all other possibilities such as leaking Auto Gas Lift, communication between zones, seal bore integrity failure.

This was confirmed by production logs which indicated a leak in Full Bore Isolation Vale vent ports and confirmed that Auto Gas Lift is functioning properly.

These findings were significant as the well was saved from a possible workover or sidetrack and production was enhanced as well.
Cement Slurry Design to Prevent Destabilization of Hydrates in Deepwater Environment
Authors: Ravi Kris , Moore Seth
Published: March 2008

Hydrates present challenges to drilling, cementing, and producing in deepwater environments. If the hydrates are destabilized during well operations, gas or solids could rise to the surface and create problems. Therefore, there is a compelling need to prevent destabilization of hydrates from drilling to producing operations in the life of the well.

The volume of cement slurry in the surface casing is great because of the large annulus, and this slurry volume results in a great amount of heat generated during slurry hydration. Further, during production hydrocarbons could increase the temperature of the surrounding formation. These factors could destabilize the hydrates.

Cement slurries are designed to lower the heat of hydration while meeting or exceeding the other properties needed for successful deepwater cementing. Heat of hydration is reduced by a factor of more than two when compared to the conventional cement slurry design. The improved cement slurry designs lower considerably the thermal conductivity of the set cement sheath.

Laboratory tests designed to measure and optimize the heat of hydration are discussed and field implementation of these slurries and results are presented. Results presented in this paper should help the industry construct and produce wells without destabilizing the hydrates, thus promoting well safety and economics.
BP's Subsea Developments: Past Successes and Future Challenges
Authors: Botros Fikry , Noel Cornelia , Brookes David , Perry Robert
Published: March 2008

BP's successful track record in subsea developments dates back to the 1970's. Since that time, BP has developed about 180 subsea wells which are producing some 800,000 bpd of oil and gas. These developments have endowed BP with unique knowledge and experience in the development and operation of an eclectic mix of subsea installations worldwide. The envelope of our existing developments cover water depths exceeding 2500m, shut-in pressures of 1000 bars combined with 135°C temperatures, and tied back to all major types of floating hubs at offset distances of up to 90km.

The next wave of deepwater and subsea projects will require the development of reservoirs with compound issues: HPHT (1400 bars, 177°C), heavy crude, low permeability, low pressure among others. Some of these reservoirs are located in remote regions with few offshore host facilities and/or ecologically sensitive environments with extreme climatic swings.

This paper presents an overview of BP's many milestones in subsea projects over the years. The intent is to underscore our achievements and capabilities in project development and operations, enumerate the challenges facing the next generation of subsea developments, and outline the company's approach to technology development to ensure success.
Need for New a Recruitment Strategy
Authors: Parmesh Manoj
Published: March 2008

Recruitment has become the most challenging Human Resource function across all industries today. For a specialized vertical like Oil & Gas, the challenges are still enormous. Recruitment in Oil & gas industry is getting more and more complicated as the environment in which the upstream industry operates is very global.

Why do we find it difficult to attract new talent?

There are three main reasons for this. Firstly, the industrial activity across the world is at an all time high, which has in turn created more jobs thus making availability of personnel very difficult. Secondly, the industry has not exactly attracted a lot of people over the last twenty years for factors such as industry cyclicality, new technology, public perception etc to name a few. Thirdly the baby boomers generation is approaching retirement and the younger generation is not in enough numbers or experienced enough to fill the gap.

Need for a new strategy

Considering the above realities, there is a dire need for organizations in the industry to come up with a completely new recruiting strategy to ensure that its aggressive growth targets are not choked by the issues surrounding virtually all companies alike in the industry. The need of the hour is to shift from a traditional reactive recruiting towards a more proactive recruiting, clearly understanding the various factors of the job market. This recruiting strategy always revolves around four aspects.
AHSG Tag Single Nucleotide Polymorphisms Associate With Type 2 Diabetes and Dyslipidemia
Authors: Andersen Gitte , Burgdorf Kristoffer Sølvsten , Sparsø Thomas , Borch-Johnsen Knut , Jørgensen Torben , Hansen Torben , Pedersen Oluf
Published: March 2008

OBJECTIVE—The gene encoding the α2 Heremans-Schmid glycoprotein (AHSG) is a credible biological and positional candidate gene for type 2 diabetes and the metabolic syndrome, and previous attempts to relate AHSG variation with type 2 diabetes and obesity in Swedish and French Caucasians have been largely successful. We related seven frequent AHSG tag single nucleotide polymorphisms to a range of metabolic traits, including type 2 diabetes, obesity, and dyslipidemia.

RESEARCH DESIGN AND METHODS—The polymorphisms were genotyped in 7,683 white Danish subjects using Taqman allelic discrimination or chip-based matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, providing a statistical power of >99% to replicate previous findings. Data were analyzed in case-control and haplotype settings, and quantitative metabolic traits were examined for association. Moreover, epistatic effects between AHSG variants and insulin receptor substrate-1 (IRS1) and β-2-adrenergic receptor polymorphisms were investigated.

RESULTS—The −469T>G (rs2077119) and IVS6+98C>T (rs2518136) polymorphisms were associated with type 2 diabetes (P = 0.007 and P = 0.006, respectively, or Pcorr = 0.04 and Pcorr = 0.03, respectively, following correction for multiple hypothesis testing), and in a combined analysis of the present and a previous study −469T>G remained significant (odds ratio 0.90 [95% CI 0.84–0.97]; P = 0.007). Furthermore, two AHSG haplotypes were associated with dyslipidemia (P = 0.003 and Pcorr = 0.009). Thr248Met (rs4917) tended to associate with lower fasting and post–oral glucose tolerance test serum insulin release (P = 0.02, Pcorr = 0.1 for fasting and P = 0.04, Pcorr = 0.2 for area under the insulin curve) and improved insulin sensitivity estimated by the homeostasis model assessment of insulin resistance (9.0 vs. 8.6 mmol · l−1 · pmol−1 · l−1; P = 0.01, Pcorr = 0.06). Indications of epistatic effects of AHSG variants with the IRS1 Gly971Arg polymorphism were observed for fasting serum triglyceride concentrations.

CONCLUSIONS—Based on present and previous findings, common variation in AHSG may contribute to the interindividual variation in metabolic traits.
Increased Expression and Activity of the Transcription Factor FOXO1 in Nonalcoholic Steatohepatitis
Authors: Valenti Luca , Rametta Raffaela , Dongiovanni Paola , Maggioni Marco , Ludovica Fracanzani Anna , Zappa Marco , Lattuada Enzo , Roviaro Giancarlo , Fargion Silvia
Published: March 2008

OBJECTIVE—Nonalcoholic fatty liver, affecting 34% of the U.S. population, is characterized by hepatic insulin resistance, which is more marked in the presence of steatohepatitis, and frequently precedes hyperglycemia. The molecular mechanisms underlying the relationship between fatty liver and insulin resistance are still undergoing definition and have not been evaluated in humans. Our aim was to evaluate the relationship between insulin resistance and the expression and regulation of forkhead box–containing protein O subfamily-1 (FOXO1), a transcription factor that mediates the effect of insulin on the gluconeogenic genes PEPCK and glucose-6-phosphatase catalytic subunit (G6PC).

RESEARCH DESIGN AND METHODS—FOXO1, PEPCK, and G6PC mRNA levels were evaluated in 84 subjects: 26 with steatohepatitis, 28 with steatosis alone, 14 with normal liver histology without metabolic alterations, and 16 with hepatitis C virus chronic hepatitis, of whom 8 were with and 8 were without steatosis. Protein expression and regulation of FOXO1 and upstream insulin signaling were analyzed in a subset.

RESULTS—Expression of PEPCK was higher in steatohepatitis compared with steatosis alone and normal liver, and it was correlated with the homeostasis model assessment of insulin resistance (HOMA-IR) index. FOXO1 mRNA levels were higher in steatohepatitis, correlated with PEPCK and G6PC mRNA and with HOMA-IR. FOXO1 upregulation was confirmed at protein levels in steatohepatitis and, in the presence of oxidative stress, was associated with decreased Ser256 phosphorylation, decreased Akt1, and increased Jun NH2-terminal kinase-1 activity. Consistently, immunohistochemistry showed increased FOXO1 expression and nuclear localization in steatohepatitis. FOXO1 mRNA levels correlated with nonalcoholic steatohepatitis activity score and were modulated by drugs counteracting hepatic lipogenesis.

CONCLUSIONS—FOXO1 expression and activity are increased in patients with steatohepatitis, and mRNA levels are correlated with hepatic insulin resistance.
Ultrasonic Measurements of Contact Area and Pressure Distribution of a Pneumatic Tire on a Rigid Surface
Authors: Pau Massimiliano , Leban Bruno , Baldi Antonio
Published: March 2008

Contact phenomena which occur at the tire-ground interface play a crucial role in most issues related to optimal performances of the vehicle, safety, comfort, and energy consumption. Thus, it is essential to have available experimental tools capable of supplying detailed information about the main contact parameters (size and shape of nominal contact area and contact pressure distribution), especially when unknown or unpredictable external conditions make it difficult to use numerical tools in assessing them. Although a number of laboratory techniques have been devised to address this problem, here we propose a novel approach that exploits the property of ultrasonic waves to be differently reflected by a contact interface depending on its stress state. This noninvasive method is capable of supplying in real-time detailed maps of contact conditions as well as quantitative information with regard to geometric features of the contact area and contact pressure distribution values after suitable postprocessing procedures.

This study reports the results of the application of the ultrasonic method in the case of contact of a motor-bicycle tire on a rigid surface. A number of tests were carried out under different conditions with regard to inflation pressure and applied load. In each case, the raw reflection data were converted into graphic maps that display the contact area features and contain information about contact pressure. Moreover, to assess the quantitative reliability of the technique, ultrasonic data were compared with those obtained by means of a commercial pressure-sensitive film. The results are discussed to evaluate the capability of the ultrasonic method to correctly capture contact patch features.
Analytical Tire Forces and Moments with Physical Parameters
Authors: Salaani Mohamed Kamel
Published: March 2008

The pneumatic tire behaves as a highly nonlinear system. Its complexity has limited the development of a complete and reasonable theory governing its mechanics. Practical tire models used in vehicle dynamics simulation and tire-related research rely basically on curve-fitted experimental data and empirical adjustments of theoretical models. This paper introduces a validated analytical model based on the physical properties of the tire by formulating the shear contact phenomena with elliptical normal pressure distribution and planar stress-strain laws. Adjustments are introduced to current methods for estimating distributed stiffness, the use of friction, and the forces saturation phenomena. The analytical model is formulated and normalized to accept tire physical parameters that are easily estimated from force and moments measurements. These parameters are universal to all tires: lateral and longitudinal stiffnesses, aligning pneumatic trail, overturning effective moment arm, and frictional properties. The method of using fundamental mechanics for modeling contact patch forces and moments with tire physical parameters constitutes a significant advancement. The tire model is validated with experimental data.
Electrochemical determination of muscle relaxant drug tetrazepam in bulk form, pharmaceutical formulation, and human serum
Authors: Ghoneim Mohammed , El-Desoky Hanaa , El-Ries Mohammed , Abd-Elaziz Ashraf
Published: March 2008

Tetrazepam dissolved in the Britton-Robinson universal buffer of various pH values (2.5–11.5) containing 10 vol. % of ethanol was reduced at the mercury electrode in a single 2-electron irreversible step due to reduction of the 4,5 C=N double bond of the seven-membered ring. Differential pulse polarography (DPP) and adsorptive cathodic stripping voltammetry (AdCSV) techniques (Linear sweep LS, differential pulse DP and square-wave SW modes) for quantification of tetrazepam in bulk form and in myolastan tablets are presented. Moreover, the described linear sweep, differential pulse, and square-wave adsorptive cathodic stripping voltammetry was successfully applied in quantification of tetrazepam in spiked human serum without any prior extraction of the drug. The obtained results showed an increased sensitivity of the described electro-analytical procedures for the quantification of tetrazepam in the following order DPP, DP-AdCSV, LS-AdCSV, and SW-AdCSV, since the observed limits of tetrazepam quantitation by these electroanalytical techniques were 5 × 10−6 mol L−1, 3 × 10−7 mol L−1, 1 × 10−8 mol L−1, and 3 × 10−9 mol L−1, respectively.
Gas chromatography with ballistic heating and ultrafast cooling of column
Authors: Krkošová Žofia , Kubinec Róbert , Jurdáková Helena , Blaško Jaroslav , Ostrovský Ivan , Soják Ladislav , Ševčík Jiří
Published: March 2008

An overview of the existing methods for minimization of the analysis time in gas chromatography (GC) is presented and a new system for fast temperature programming and very fast cooling down is evaluated. In this study, a system of coaxial tubes, a heating/cooling module (HC-M), was developed and studied with a capillary column placed inside the HC-M. The module itself was heated by a GC oven and cooled down by an external cooling medium. The HC-M was heated at rates of up to 330 °C min−1 and cooled at the rate of 6000 °C min−1. The GC system was prepared for the next run within a few seconds. The HC-M permits good separation reproducibility, comparable with that of a conventional GC, expressed in terms of relative retention times and peak areas of analytes reproducibilities. The HC-M can be used within any commercial gas chromatograph.
Influence of process parameters on the epoxidation of 2-buten-1-ol over titanium silicalite TS-1 catalyst
Authors: Wróblewska Agnieszka , Ławro Ewelina , Milchert Eugeniusz
Published: March 2008

The influence of process parameters on the epoxidation of 2-buten-1-ol with 30 % hydrogen peroxide using the titanium silicalite TS-1 is presented. The studies were carried out under autogenic pressure (in autoclave). Methanol was used as a solvent in this process. The influence of temperature, 2-buten-1-ol to hydrogen peroxide mole ratio, amount of solvent used, TS-1 catalyst content, and reaction time on the reaction was studied. The major product of this reaction, 2,3-epoxybutan-1-ol (EB), has numerous applications in chemical industry.
Electrochemical behaviour of the LiF-(CaF2)-La2O3 system
Authors: Ambrová Marta , Jurišová Jana , Sýkorová Alexandra , Uher Dalibor , Danielik Vladimír , Híveš Ján
Published: March 2008

The electrochemical behaviour of the LiF-La2O3 and LiF-CaF2-La2O3 systems was investigated by means of cyclic voltammetry. Several types of working electrodes (spectrographic pure graphite, W, Mo, Ni, Cu) were used. It was found that chemical reactions take place in the system during the dissolution of lanthanum oxide. The reduction of lithium cations occurred at the most positive potential from the species formed in the melt on ‘inert’ cathodes (W, Mo). The reactive cathodes (Cu, Ni) allowed the lanthanum deposition with depolarisation.
A new method of evaluation of element pollutant mobility in sediments
Authors: Vojteková Viera , Nováková Jarmila , Mackových Daniela , Blašková Jana
Published: March 2008

The application of a strong chelating agent for the screening test of element mobility in sedimentary systems was investigated. Single-step and sequential extraction procedures were applied to four sediment samples collected from an industrially polluted region of Eastern Slovakia. A sequential extraction procedure (SEP), recommended by the Institute for Reference Materials and Measurements (IRMM), was applied and used as a reference extraction method. A single-step extraction with 0.05 mol dm−3 ethylenediaminetetraacetic acid (EDTA) was adapted for sediments when extraction conditions were optimised. The extraction efficiency of the single-step procedure was compared with that of SEP. The contents of elements extracted by Na2EDTA were in good agreement with the sum of the first three steps of the SEP for Fe, Mn, and Co. Na2EDTA can therefore be considered capable to extract the majority of elements associated with the reducible sedimentary phase — bound to Fe and Mn oxides in the regional geological conditions of the monitored region. Thus, Na2EDTA extraction of Fe and Mn can serve as an economical, time-saving supplementary test for the IRMM procedure.
Thermooxidative stability of polymethyl methacrylate containing nanoparticles of silica/titania and silica/zirconia
Authors: Šimon Peter , Zhong Wei , Bakoš Dušan , Hynek David
Published: March 2008

The influence of silica/titania and silica/zirconia nanoparticles on thermooxidative degradation of PMMA was studied by non-isothermal thermogravimetry. Kinetic parameters describing the length of the oxidation induction periods were obtained from the treatment of the dependence of oxidation onset temperature on heating rate. Using these parameters, the protection factors of nanoparticles have been calculated. It was found that SiO2/TiO2 nanoparticles increase the thermooxidation stability of PMMA where the stabilizing effect, expressed as the protection factor, depends on temperature only slightly. The stabilizing effect of SiO2/ZrO2 is much stronger than that of SiO2/TiO2 and decreases with increasing temperature.
Polyaniline-coated cellulose fibers decorated with silver nanoparticles
Authors: Stejskal Jaroslav , Trchová Miroslava , Kovářová Jana , Prokeš Jan , Omastová Mária
Published: March 2008

Cellulose fibers of 20 μm in diameter and aspect ratio of 2 or 10 were coated with protonated polyaniline (PANI) during the oxidation of aniline hydrochloride with ammonium peroxydisulfate in an aqueous medium. The presence of PANI has been proved by FTIR spectroscopy. The conductivity increased from 4.0 × 10−14 S cm−1 to 0.41 S cm−1 after coating the fibers with PANI. The percolation threshold in the mixture of original uncoated and PANI-coated fibers was reduced from 10 mass % PANI to 6 mass % PANI, as the aspect ratio changed from 2 to 10. The subsequent reaction with silver nitrate results in the decoration of PANI-coated cellulose fibers with silver nanoparticles of about 50 nm average size. The content of silver of up to 10.6 mass % was determined as a residue in thermogravimetric analysis. FTIR spectra suggest that the protonated emeraldine coating changed to the pernigraniline form during the latter process and, consequently, the conductivity of the composite was reduced to 4.1 × 10−4 S cm−1, despite the presence of silver.
Effect of crown ethers on the solvent extraction and separation of lanthanide(III) ions with 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one
Authors: Petrova Maria , Dukov Ivan
Published: March 2008

Synergistic solvent extraction of 14 lanthanides with mixtures of 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one (HP) and the crown ethers (S), 18-crown-6, benzo-18-crown-6 or dibenzo-18-crown-6 from an aqueous chloride medium with the constant ionic strength of 0.1 mol dm−3 was investigated using benzene as a diluent. The composition of the species extracted was determined as LnP3 · S. The addition of a crown ether to the chelating extractant produced rather significant synergistic effects. On basis of experimental data, values of equilibrium constants, synergistic coefficients, and separation factors were calculated.
Rapid solidification processing in molten salts chemistry: X-ray analysis of deeply undercooled cryolite-alumina melts
Authors: Korenko Michal , Kucharík Marián , Janičkovič Dušan
Published: March 2008

Rapid solidification processing (cooling rate from the interval 105–106 K s−1) was used to prepare deeply undercooled cryolite-alumina melts. Such prepared samples were analyzed by the XRD method. Besides cryolite, XRD patterns belonging to ι-Al2O3 were recorded. The influence of annealing on the XRD patterns of deeply undercooled melts was also investigated.