bluuebunny/crossref_metadata_2025 huggingface dataset:
An Efficient Horizontal Cased Hole Multistage Stimulation Well: China Case Story
Authors: Liu Guang Hua , Cui Hui Kai , Fould Jeremie , Lee JS , Wang Hai Long , Zhang Xing Guo , Aviles Isaac , Baihly Jason
Published: March 2012

Drilling activity has been steadily ramping up in China to meet the countries energy demand and government production goals. This is moving some activity to previously unexploited ‘tight’ formations requiring hydraulic fracturing to produce economically. These formations have historically been producing with stimulated vertical wells and some horizontal un-stimulated wells. Many of these tight reservoirs exist in the Bohai Basin of Eastern China.

In order to quickly ramp up production to meet the governments’ goals, new drilling and completion techniques are being used including completing horizontal wells with multistage hydraulic fractures in some fields. In some low producing areas new methods of isolating and stimulating wells are being investigated by the operator. New stimulation isolation methods must be streamlined as much as possible in order to achieve the production goals quickly and economically.

One of the new completion systems that was developed for cemented wells requiring multistage stimulation us generically called the treat and produce (TAP) completion system. This high efficiency completion system has recently been used in China’s Dagang field to stimulate a horizontal well.

The TAP system was run by the operator in the Dagang field, where cased and cemented vertical completions are common and require artificial lift to produce. Horizontal cemented completions have been recently introduced as a means to increase field wide production. Although plug and perforating methods are applicable for these wells, the client turned to a more efficient solution. TAP systems permit continuous pumping operations to be performed while precisely placing multiple hydraulic fracture treatments along the horizontal section; immediate flowback is possible for further production and efficiency gains.

In order to efficiently complete the horizontal well, a treat and produce (TAP) system was used in order to complete the well. This completion system uses a series of sliding sleeve valves that are installed as part of the casing string. These valves are actuated by pressure and sliding sleeves with graduated ball seats.

This paper describes the TAP completion system and its application in the Dangang field in China. TAP completions enabled optimized fractures placement and propagation in cemented completions that resulted in efficiency and production gains for the client, proving the application for the field. By means of a case history, the specific design and operation of the TAP completions system are discussed.
Evolution of Production Logging Technologies and Capabilities: In Quest to Know the Unknown, A Brownfield Case Study, Mumbai High, ONGC Western Offshore
Authors: Chandra Yogesh , Ogra Konark , Verma Vibhor , Pandey Arun , Sinha Ravi , Kumar Ajit
Published: March 2012

Production logging traditionally has been used to describe the flow characteristic of a well. Over the years with the advancement of the technology, for the techno economic success, deviated and horizontal wells have been drilled. Application of highly deviated and horizontal wells for field development primary recovery is now a worldwide practice.

Diagnosing production problems in a near horizontal environment is a herculean task; complex flow regimes in highly deviated well aggravate complications. At the same time, with advancement in completion system design, it has become imperative to evaluate the effectiveness of the new completion design. Unfortunately traditional production logging techniques have not been successful in these conditions.

One of the key issues in diagnosing production problems is detecting and distinguishing hydrocarbons in high water cut wells with water phase flowing as continuous medium at the low side and dispersed hydrocarbon phase at the high side of wellbore. Technologies like the digital entry fluid imaging tool and gas holdup optical sensor tool have proven to provide accurate results. For horizontal and highly deviated wells where recirculation, crossflow, and phase segregation further complicate the flow behavior, complete imaging of the wellbore is needed to characterize the wells.

In brownfield scenario, the complications aggravate and may require real-time decision making and intensive data analysis. Some of the typical brownfield issues are scale buildup due to immense water injection for pressure support, which is required for efficient oil displacement, complex fluid flow regime, recirculation due to insufficient lift, and casing damage resulting in unwanted formation water entry.

The study provides the most prolific summary and guide for case studies, success stories and lessons learned from the Mumbai High field in the last decade; evolution of the production logging tool from the most standard unit to multipoint digital entry fluid imaging, gas holdup optical sensor tools to identify and distinguish between the three fluid phases. The paradigm shifts towards the key technologies like flow scan imager to evaluate the complex borehole fluid behavior, flow regimes identification is also presented in this paper. The results derived are indispensable for future well placement campaign
Innovative Subsea Intervention Plan to Avoid Production Loss-Case Study
Authors: Reddy Shiva , Rama Sumit
Published: March 2012

The D1D3 gas field in Krishna Godavari basin has deep water Subsea structures namely well, manifold, Subsea Distribution Assembly (SDA), Deep Water Pipeline end manifold (DWPLEM). These structures will be monitored and controlled by a Subsea Control Module (SCM) installed on each particular structure and the top side Subsea control system "iconSCU" supplied by Aker Kvaerner Subsea, Aberdeen. All SCMs have redundant Subsea Electronic modules (SEMs) with Fiber Optic communications (FO) & back up combined power signal (CPS) links connected to the top side monitoring system. SCM is a critical part of each subsea structure and if required may need to be replaced as and when failures are evident. For changing the Manifold SCM the associated flowing well to the specific manifold requires to be shut-in because the power supply to the associated well SCM is through manifold SCM via Electrical Distribution Box and hence causing production loss. To avoid this production loss, an innovative approach has been developed. The highlight of this approach is SCM change-out without taking any shutdown of the flowing wells or interrupting the production by using redundancy of communication and power to the manifold and well SCM in real time. While design was such that shut in of all wells for each associated manifold would be required to replace a manifold SCM, the approach described in this paper will illustrate how use of redundant power paths are used to keep all production online, while changing the manifold SCM. This necessitates designing and subsea installation of electrical distribution box/EFLs on a Deep Water Manifold while maintaining production.
Multi-dimensional NMR Technique for Wireline Formation Tester Sampling Optimization and Perforation Strategy Determination in a Brown Field, India
Authors: Ghosh Arnab , Klimentos Theodore , Singh R. K. , Nangia Viraj , Malik Sonia , Ghosh Krishnendu , Bhattacharya Shyamal , Chadha H. K.
Published: March 2012

The Neelam field is situated in south-east of the giant Mumbai High oilfield in western offshore basin of India. This field was discovered in 1987 and has been put under production since 1990. The field is presently under active water injection and the average oil production from the study area is approximately around 100 BOPD with 95 percent water-cut.

Perforation strategy determination in a brownfield carbonate reservoir under extensive water injection is very challenging. Fluid identification is critical in these reservoirs. Wireline formation tester sampling at defined depths can be very useful for downhole fluid identification. However, the sampling is a stationary measurement and depends on successful communication with the formation fluids. Multi-dimensional nuclear magnetic resonance (NMR) data can efficiently optimize the wireline formation tester operations in such critical wells by using continuous porosity and permeability at various depths of investigations. Additionally, resistivity independent fluid typing and saturation results from NMR analysis at different depths of investigation can be used to optimize the perforation strategy.

Our study established a workflow for designing an efficient completion plan and perforation strategy by integration of multi-dimensional NMR and formation tester wireline logging technologies in a single acquisition run in the Neelam field. However, the workflow is applicable to similar reservoirs elsewhere in the world. The objective was to enhance oil recovery and reduce water-cut and rig-time. NMR data were used to optimize the formation tester operations by identifying possible tight zones. Moreover, the NMR saturation profiling results provided continuous fluid typing and fluid saturations at different depths of investigations. Formation tester fluid sampling was carried out at discrete station depths in the same run after NMR acquisition; the formation tester station measurements of reservoir mobility and in-situ fluid analysis were then used to validate the continuous NMR log derived fluid characterization and permeability. Based on all this integrated workflow and timely analysis the best possible completion strategy was decided and perforation intervals were optimized. The well is presently producing around 270 BOPD with a 30 percent water-cut.
Advances in Invert Emulsion Performance through Novel Emulsifier Chemistry
Authors: Young Steve , De Stefano Guido , Lee John
Published: March 2012

As wellbores continue to be drilled deeper and farther than ever before, the need for improved drilling fluid systems that optimize fluid performance in harsh and challenging environments is at its highest demand.

Invert emulsion fluids are frequently chosen due to their high performance and low risk in various applications. Invert fluids are a particularly good choice when dealing with extreme environments, such as those with surface temperatures as low as - 26C (-15F) or those wells having bottom hole temperatures in excess of 250C (485F). Invert fluids are typically the preferred choice over water-based alternatives in deepwater and extended reach wells because of their inherently better lubricity and improved wellbore stability. The most important component of the invert fluid is the surfactant package, which maintains the solids in an oil-wet state, assists in filtration control, and stabilizes the internal phase of the fluid.

The latest developments in surfactant chemistries designed for invert emulsion fluids has resulted in a significant improvement in the performance of these fluid systems. Newly developed systems allow for simplified engineering due to formulation flexibility across temperature and density, high internal phase ratios with low viscosity, emulsion stability at temperature extremes, and a greener chemical profile. Each of these has a positive effect on drilling economics, environmental compliance, logistics, and health and safety.

This paper will review the new surfactant technologies, describing both their advantages and drawbacks from the standpoints of drilling performance and applicability, showing example data leading to these conclusions. The authors will also review the recent field usage of the surfactants described.
Flow Assurance Challenges - FPSO Based Development of MA Deep Water Field
Authors: Singh Sunil Kumar
Published: March 2012

MA (D-26) field in KG DWN 98/3 (KG D6) block is located on East Coast of India, about 60 km away from the Onshore Terminal (OT). This is India’s first deep water oil and gas field developed and being operated by Reliance Industries Limited (RIL). The water depth in this field varies from 1100m to 1400m. This field was put on production through FPSO in September 2008 and production was gradually ramped up to 35,000 BOPD and 8.5 MMSCMD gas.

MA field had major flow assurance challenges of hydrate formation, wax and scale deposition and slug flow. This paper describes the strategy adopted to address the flow assurance challenges and the lessons learnt from practical field experiences related to three distinct areas of MA field operations:Field start up and production from wells through the subsea manifold and risers.Changeover of gas injector well into a producer.Gas export from FPSO to Onshore terminal.

The initial startup of the field highlights the importance of having a suitable fluid in the production tubing to minimize the J-T effect across the subsea choke to prevent hydrate formation. Startup of a well also posed slug handling challenge which was mitigated by using topside chokes and adequate slug handling capacity of separators. The hydrate management strategy developed for successfully managing the shutdown and start ups within the available cool down period of 4-5 hours for MA field is discussed.

Changeover of gas injector into gas producer had its challenge of understanding the well bore temperature dynamics. Continuous injection of methanol at the well head of the changeover well was resulting in carryover of methanol in the crude oil/gas at the FPSO which called for a relook at the hydrate management strategy.

Comparison of the options of flowing the dehydrated gas in trunk pipe line containing pre commissioning fluid (MEG-Water) vis a vis vacuum drying of the trunk pipeline for gas export from FPSO to Onshore Terminal is discussed and the field experience is presented.
Use of Amplitude Inversion in Facies Characterization and Appraisal of a Deep-water Gas Discovery: A case study
Authors: Arsalan Syed. I. , Sharma Sandeep
Published: March 2012

Deep water reservoirs, in general, exhibit wide variation in facies characteristics because of their complex depositional processes and sedimentation pattern. Characterization of these reservoir facies with respect to their spatial extension and property distribution, during the appraisal phase particularly when the well control is sparse, is quite challenging and difficult.

This paper, through a case study, discusses about an approach where amplitude inversion and the inverted data volumes are used in the characterization and appraisal of a gas discovery in the lower slope deep-water Miocene channel-lobe complex in the east-coast of India that has only four drilled wells in 150 sq.km area. A combined inversion of three seismic angle stacks into P-impedance, S-impedance and Vp/Vs is performed and a Gas Indicator Index (GII) volume is generated which proves to be a reliable attribute for identification and mapping of reservoir facies. Using the GII and S-Impedance volumes in combination, the reservoir facies geometry and quality are mapped, that are observed to be consistent with the geological interpretation.
CBM Prediction: A Case Study of Field Scale Development in Bokaro Basin, India
Authors: Roy Kalyan Kumar , Parulkar S N
Published: March 2012

CBM is likely to address in a limited way the world's growing energy needs. In India the epicenter of such a process is geographically active in the east, predominantly known for conventional coal mining. Devoid of any known natural gas resource, the area though conducive for CBM production, commercial prediction needs utmost care and caution, as supply commitment is never equipped with fall back option. The geological model thus for Barakar Formation of Bokaro Field is defined with reasonable confidence for three potential CBM seams assessed through 3 vertical wells with a deliverability 10,000 m3/d for the first tested well. Proven CBM potential volumes estimated thus needs to be translated into a way forward programme of monetization firmed up through simulation based profile.

A comprehensive full field dual porosity/permeability simulation model, incorporating Langmuir isotherm and GC data generated across the geographical spread is built to understand the process intricacy. Effort to history match the initial Qw with time in all CBM simulation as a depressurization event is a difficult proposition as interruption in Qw, coupled with Wp bookkeeping are often very subjective. However, permeability/volume modifiers within acceptable limits led to replicating near history of Qg and Gp. The prediction was QC'd on single well forecasting basis through other commercial software, and the profiles though identical was in substantial variation in gas breakthrough timing, the possible reasons identified as a learning for the future.

Field scale development with an optimized variant of 38 vertical wells at 60 acres well spacing envisages peak Qg of 1.3 LCMD and RF being 32% after 15 years. The criticality is however well scheduling designed to cater to the industry needs of a reasonable plateau period.

This paper assimilates the lessons learnt from the applications of simulation to be used for devising field scale CBM development strategy and is suggestive of the Do's and Don'ts of initial data generation and lists caution in the prediction specially the depressurization process, well spacing criteria, drilling schedule for plateau generation.
Advanced Application of Borehole Images and Acoustic Logs in Building Robust Geomechanical Model for Tapti-Daman Field, Western Offshore India
Authors: Kumar Rajeev , Rao Dhiresh Govind , Parashar Sarvagya , Swain Saraswat , Sikdar Koushik , Majithia P P , Suresh G. V
Published: March 2012

Tapti-Daman is one of the established prolific gas producing clastic sub-basin in offshore Mumbai, India. Paleo-Miocene shallow sands are the dominant reservoir in this area. Drilling surprises have been observed frequently in this area due to geomechanics-related wellbore instability. We present a case study showcasing detailed analysis and integration of multi-well advanced acoustic and borehole image data set. Considering the uncertainty with the variation in stress regime on well basis as compared to regional geological setting, it becomes critical to identify stress regime in order to optimize mud weight programme to drill high inclined wells where safe mud weight window becomes narrow. The borehole image analysis leads to identification of breakouts and drilling induced fractures which reveal horizontal stress directions whilst sonic anisotropy analysis provides more robust insight on maximum horizontal stress direction based on fast shear azimuth. In addition, radial profiles of fast shear and slow shear were used to invert and determine absolute values of maximum and minimum horizontal stress magnitudes. Integration of the high resolution data set reveals the present day stress regime of the study area is strike slip (σH>σV>σh) regime. Using the quantitative values of horizontal stresses determined at different depth intervals, a post-drill Mechanical Earth Model (MEM) was developed to perform history matching of predicted failure with observed drilling events. This model was then validated with another well in the field which clearly demonstrated the value addition of the sonic answer products and image analysis. Similar workflow can be adopted to address sanding propensity to optimize completion design to mitigate or manage sand production.
A New Generation of Flat Rheology Invert Drilling Fluids
Authors: Young Steve , Friedheim Jim , Lee John , Prebensen Ole Iacob
Published: March 2012

Flat Rheology Invert Drilling Fluid (FRIDF) has been successfully used for deepwater drilling due to its outstanding performance in providing excellent hole cleaning, temperature-independent rheology profile, good barite sag control and good ECD control. The high performance is achieved by using correct combinations of emulsifier, wetting agent, rheology modifiers and supplementary viscosifiers. Because of the multiple products used, the FRIDF can be complex to engineer and manage. An improved and simplified flat rheology system has been developed to aid in the field engineering and ease of system maintenance without sacrificing fluid performance.

The newly developed flat rheology system utilizes a single emulsifier component to provide dual functions of emulsification and surface wetting. This helps to improve emulsion stability and enhance thermal stability and fluid lubricity. The system can be formulated for deepwater applications with mud weights up to 18.0 lb/gal and temperatures up to 350°F. In addition, the system uses a new rheology modifier that provides a temperature-independent rheology profile for hole cleaning, barite suspension, ECD management and lost circulation control.

Recent field trials indicated that the new system is easy to maintain and provides good fluid performance in terms of drilling rate, ECD management, lost circulation control and hole cleaning. Even when the system was contaminated with a severe saltwater flow, there were no fluid-related problems before the synthetic/water ratio was restored. The new fluid system exhibited flat rheology profiles and non-progressive gel structures. Hydraulic modeling showed excellent hole cleaning with low ECDs and breaking-circulation pressure. This resulted in a noticeable reduction of lost circulation potential in lost circulation prone areas. The performance of the new flat rheology system (NFRS) also will be compared to the current system to demonstrate some advantages of the new system.
The Evolution of Completion Designs Using Alternate Path (Shunt-Tubes) Technology
Authors: Saebi Shahryar
Published: March 2012

Alternate Path* (shunt-tubes) technology has been available to the petroleum industry for well more than a decade. Its applications have expanded over time around the world ranging from single-zone cased-hole gravel packs to multizone gravel packs or frac packs and openhole gravel packs. The recent advances have expanded applicability from specialty gravel packing to a general, all-purpose technology with huge benefits. Its flexibility permits use in extremely challenging environments, allowing completions previously considered difficult or impossible.

Development of multizone packers (cup type or swellable) has helped to push the envelope for Alternate Path technology both for cased-hole and openhole applications. This technology has enabled operators to not only perform multizone gravel-pack and frac-pack completions, but also provide solutions for gravel packing in exceptional conditions such as gravel packing a new zone in presence of open perforations in the zone above, isolating unwanted zones while completing new intervals, or gravel packing in exceptional well geometry.

This paper provides a review of the recent unique completions using a shunt-tube system to overcome complicated well completion challenges and expand the limits of using this technology further.
Quick Drilling Decision Based on LWD and Downhole Fluid Profiling in a Horizontal Well - A Case Study in a Mature Carbonate Field
Authors: Kumar Ajay , Shanker Vivek , Tellapaneni Prasanna
Published: March 2012

Realtime formation evaluation is critical not only for various geomechanical applications but also for quick drilling decision making in both exploration and development scenarios. The study focuses on a horizontal development well in a carbonate field which has a thin oil column overlain by a large gas cap. Large exposure multi-lateral development wells are used to improve drainage of the oil column by reducing the tendency for gas coning.

The real time formation evaluation proved formation fluid in the landing section as gas, and as a result a quick decision was made to change the well trajectory. The well was drilled 20m down in TVD as a pilot well to perform down hole fluid profiling using the Modular Formation Dynamics Tester (MDT), however, MDT could not be carried out due to heavy mud losses and the well was plugged. Finally, it was decided to sidetrack the well.

MDT with Live Fluid Analyzer (LFA) and Compositional Fluid Analyzer (CFA) was deployed to perform downhole fluid profiling in the side tracked well to identify the hydrocarbon type and composition at 3 stations. With the help of inclinometry information well trajectory and probe orientation were monitored so that sampling points were selected with probe on the high side of hole and outside of sumps if present. Fluid scanning stations using CFA/LFA clearly indicated the fluid type as gas. Fluorescence was monitored in real time to ensure that gas samples were collected above dew point. Samples collected at 3 depths were examined at surface and to confirm the CFA result. The CFA provided the C1, C2-C5, C6+ weight fractions, GOR and apparent hydrocarbon density in real-time. The fluid analysis recorded by the CFA matched well with the known gas composition and fluid density after corrections for mud filtrate were applied.

This paper shows the importance of LWD in terms of quick real-time decision making over wire line logs which are recorded after the well is drilled up to target depth. The downhole fluid profiling in sidetracked well helped in taking quick decision as not to drill further.
Estimating Well Deliverability in Deepwater Wells With Interval Pressure Transient Testing (IPTT): A Case Study
Authors: Sundaram K. M , Kumar Nitish , Nangia Viraj , Desphande Vaibhav , Nahar Siddhartha , Jackson Richard
Published: March 2012

Deepwater is an extremely cost-intensive exploration frontier representing a high-risk/high-reward scenario. After the world’s largest deepwater gas discovery in on the east coast of India, the area has attracted several operators and activity has picked up considerably in recent years. Currently, five deepwater rigs and drillships are operating in water depths ranging from 1500 m to 3000 m. This cost-intensive scenario dictates the use of techniques which maximize quality information while minimizing rig time. Interval pressure transient testing (IPTT) on wireline and conventional testing acquire essentially the same data and use the same analytical tools. Conventional well testing methods obtain the average properties of multiple layer systems but turn out to be time-consuming and hence expensive, especially if the fluid is only water. However, wireline acquisition is much more appropriate for accessing multiple layers and is far less time consuming; additionally, it can be carried out in open holes as well. The radius of investigation identified by the progressive pressure transient is sufficiently large to determine essential reservoir properties. With IPTT, the evaluation can be made layer-wise, and these evaluations are very critical for both the exploration and appraisal stages of the field development.

IPTT has been performed in deepwater wells in India using the dual-packer configuration of wireline formation testers. IPTT is used to evaluate reservoir parameters, capture representative fluid samples, and assess commercial viability and flow potential for multiple reservoir intervals. This potentially eliminates the need for conventional well testing on expensive deepwater rigs, thus significantly reducing operating cost by use of state-of-the-art technology. This paper showcases the workflow and process involved in the impact area of formation evaluation from a reservoir dynamics perspective and use of a calibrated, continuous permeability curve in calculations of full well deliverability in case of gas discovery.
Integrated Static and Dynamic Data Analysis for Characterizing the Brown Complex Carbonate Reservoir and Applying the Findings for Water Flood Management: Case Study of Mumbai High South Field
Authors: Singh Raman Kumar , Muralidharan K , Rathor Anil Kumar , Lohar Babu Lal , Verma Shailendra Kumar , Ram Binay , Patel S K
Published: March 2012

Understanding the complexity and characterizing a carbonate reservoir with complex heterogeneity is a daunting task that various operators of the E&P industry are facing today. Though the most perfect and quantitative answer of the complexity of dynamics of the carbonates comes from full field dynamic simulation, the simulation approach is often time consuming and expensive. A quick and less expensive approach is qualitatively looking at the petrophysical and production data in an integrated way for reservoir characterization and applying the findings in further field development.

Often in the brown fields, a large amount of petrophysical and dynamic data in terms of production and pressure are available. Especially in the brown fields under extensive and prolonged water flood, studying the varying level of interaction of producer-injector pairs in the field combined with the variation in the static properties can give very useful insight in the reservoir heterogeneity and identification of preferentially water flooded areas. This interpretation can be used to improve efficiency of water flood by adding and/or relocating injectors. The above concept of integrated static and dynamic data analysis has been applied for the multilayered carbonate reservoir of Mumbai High South field.

The integrated approach of static properties validated with production-pressure data helped in identifying the in-homogeneity, interlayer communication, nature of seismic picked faults and existence of flow barriers. Also the production-injection interaction analysis helped in identifying the likely pathways of water flood and the areas lacking water injection support. The findings have been successfully validated with subsequent pressure surveys. The above study under taken for the first time for Mumbai High South field has helped in improving the water injection plan with confirmation of the planned injectors and identification of areas needing more injection support.

Although non-predictive, the technique has immense value in validation of ongoing water injection scheme, providing understanding of inter-well communication and quickly bringing out areas requiring review of the injection plan for improving its effectiveness.
Oxidation of hydroxide ions at platinum modified zeolite electrode
Authors: Mudrinic Tihana , Mojovic Zorica , Rabi-Stankovic Abu , Ivanovic-Sasic Ana , Milutinovic-Nikolic Aleksandra , Jovanovic Dusan
Published: March 2012

NaX zeolite was modified by platinum via impregnation/thermal decomposition
technique, using Pt(II)-acetylacetonate in acetone as an impregnating
solution. The samples were characterized by scanning electron microscopy
(SEM) and cyclic voltammetry methods. The mixture of modified zeolite and 10
wt % of carbon black, in a form of thin layer, was pasted to a glassy carbon
surface. With this mixture as the electrode material hydroxide ions oxidation
was studied by cyclic voltammetry. The response of modified zeolite
electrodes was compared with bare platinum electrode and platinum electrode
covered with Nafion film.
HPLC analysis, antimicrobial and antioxidant activities of Daphne cneorum L.
Authors: Manojlovic Nedeljko , Maskovic Pavle , Vasiljevic Perica , Jelic Ratomir , Juskovic Marina , Sovrlic Miroslav , Mandic Leka , Radojkovic Marija
Published: March 2012

The present study describes in vitro antimicrobial and antioxidant activities
of the methanol extracts which were obtained from the leaves and twigs of the
plant Daphne cneorum L. The antimicrobial activity of these extracts was
tested against human pathogenic microorganisms using a minimum inhibitory
concentration (MIC) values. Total phenolics and flavonoids, as well as the
antioxidant activity of the extracts were determined. The two tested extracts
showed good antimicrobial and antioxidant activities. The results of a high
performance liquid chromatographic (HPLC) method showed that
7,8-dihydroxycoumarin is one of the most abundant secondary metabolite in the
tested extracts. The results of this study clearly indicated that the
extracts of D. cneorum could be used as a potential source of natural
antioxidant and antimicrobial agents.
Development of Karl Fischer titration method using quality by design concept
Authors: Jancic-Stojanovic Biljana , Vemic Ana , Rakic Tijana , Kostic Nadja , Malenovic Andjelija
Published: March 2012

Modern trends in drug quality control are moving toward incorporating quality
into the method during its development. That course is in accordance with
Quality by Design (QbD) concept defined by ICH Q 8 (R2) guideline. This
implies that the method development begins by defining the method goals and
collecting the relevant data, i.e. analyzing the properties of a given active
pharmaceutical ingredient and evaluating the optimal experimental conditions.
It is followed by a risk assessment defined by systematic robustness testing
with the application of experimental design, while the final confirmation of
the method reliability is done through the complete validation tests. In this
paper, development of Karl Fischer titration for water determination in
active pharmaceutical substance clindamycin phosphate is presented. Karl
Fischer titration (KFT) is a widely used method in the pharmaceutical
industry for determination of water content. For the analyzed substance, the
European Pharmacopoeia suggests a relatively large amount of samples for the
determination of water, so the objective of this study is to confirm the
applicability of the developed method for the determination of water in small
amount of samples applying QbD approach. According to QbD rules, detail
development of coulometric Karl Fischer titration for water determination in
clindamycin phosphate was done. For robustness testing fractional factorial
design 24-1 was successful applied and confirmed that method was robust.
Robustness was evaluated using statistical and graphical methods. Also,
design space was defined so the region, in which factors could be changed
without significant changes in water content, was defined. At the end, other
validation parameters were determined and it was proved that analytical test
system was capable of providing useful and valid analytical data.
Enzymatic kinetic method for determination of propranolol hydrochloride in pharmaceuticals based on its inhibitory effect on cholinesterase
Authors: Stankov-Jovanovic Vesna , Mitic Violeta , Ilic Marija , Mandic Ljuba , Nikolic-Mandic Snezana
Published: March 2012

Propranolol, a widely used beta-blocker, inhibits the reaction of enzyme
cholinesterase hydrolysis. Measurements of the hydrolysis rate differences
between and inhibited reactions, allows the development of a kinetic method
for its determination. Both systems, enzyme-substrate-chromogen and
enzyme-substrate-chromogen-inhibitor, were characterized through biochemical
kinetic parameters (KM = 0.326-0.330 mmol/L; Vmax = 40-42.99 ?mol/Lmin),
inhibition type was recognized as competitive, and inhibition constant, Ki,
was determined to be 22.60 ?mol/L. The detection and quantification limits
were calculated as 0.004 and 0.0136 ?mol/L, respectively. Accuracy and
precision of proposed methods were tested. Proposed method is characterized
with good sensitivity, selectivity, simplicity and rapidity, thus it is
convenient for clinical applications.
Relaxation of quasi-stationary states in long range interacting systems and a classification of the range of pair interactions
Authors: Marcos Bruno , Gabrielli Andrea , Joyce Michael
Published: March 2012

Systems of particles interacting with long range interactions present generically ”quasi-stationary states” (QSS), which are approximately time-independent out of equilibrium states. In this proceedings, we explore the generalization of the formation of such QSS and their relaxation from the much studied case of gravity to a generic pair interaction with the asymptotic form of the potential v(r) ∼ 1/r γ with γ > 0 in d dimensions. We compute analytic estimations of the relaxation time calculating the rate of two body collisionality in a virialized system approximated as homogeneous. We show that for γ < (d − 1/2), the collision integral is dominated by the size of the system, while for γ > (d − 1/2), it is dominated by small impact parameters. In addition, the lifetime of QSS increases with the number of particles if γ < d − 1 (i.e. the force is not integrable) and decreases if γ > d − 1. Using numerical simulations we confirm our analytic results. A corollary of our work gives a ”dynamical” classification of interactions: the dynamical properties of the system depend on whether the pair force is integrable or not.
Coronary artery bypass surgery in patients with low EuroSCORE preoperative risk
Authors: Zdravkovic Marija , Ristic Miljko , Krotin Mirjana , Milic Natasa , Soldatovic Ivan , Nedeljkovic Ivana , Peruničić Jovan , Zdravkovic Darko
Published: March 2012

Patients with EuroSCORE <2 are usually considered to have a low surgical risk and the lowest mortality. In our study preoperative factors in a group of 250 consecutive low-risk patients (EuroSCORE<2), who underwent first isolated coronary artery by-pass surgery during 1999 and 2000., were analyzed. Cumulative follow-up period was 1178.48 patient-years and the primary clinical outcome was all-cause mortality. Patients’ average age was 59.2±7.5 yr. The following preoperative risk factors of increased 5-year mortality were identified: older age (P<0.001), smoking, prior non-recent myocardial infarction and reinfarction, anteroseptal localization of myocardial infarction (P<0.001), poor ejection fraction<=35% (P<0.001), dilatative cardiomyopathy (P<0.001), wall motion systolic index 〉2 (P<0.001), left atrial dilatation (P<0.001), mitral regurgitation more than 2+ (P<0.001), presence of left main disease, triple vessel coronary artery disease (P<0.001), absence of collaterals (P<0.001) and presence of more than 3 distal anastomoses. Through the present study it has been shown that it is possible to identify a subgroup of patients with low operative mortality and excellent 5-year survival after surgical treatment for coronary artery bypass surgery using preoperative clinical, echocardiographic, coronarographic and intraoperative data, even in difficult conditions of the civil war in the region.
Tick Species (Acari: Ixodoidea) Distribution, Seasonality and Host Associations in Romania
Authors: Coipan Elena , Vladimirescu Alexandru , Ciolpan Octavian , Teodorescu Irina
Published: March 2012

Tick Species (Acari: Ixodoidea) Distribution, Seasonality and Host Associations in Romania

By integrating the literature data with those derived from personal investigations, the authors present the distribution of the 27 tick species (25 ixodids and 2 argasids) identified up to now in Romania, as well as some aspects regarding their abundance, seasonality and host associations. Altogether, 1439 tick records (of which 256, covering 25 counties, belong to the authors themselves) were georeferenced using EpiMap (an ArcView®-compatible GIS) from CDC's EpiInfo™ software package (v. 3.5.1), on a level 2 LAU (Local Administrative Units) shapefile. The resultant distribution maps and the data on seasonality and host associations may prove to be a useful reference system for subsequent studies on different tick species' distribution, ecology and biology, as well as a predictive tool for human and veterinary medicine, bearing in mind the vectorial role that ticks play in some dangerous diseases for man and livestock.
Leptochelia Vatulelensis (Crustacea: Tanaidacea), A New Species From Anchialine Caves of the South-Western Pacific
Authors: Guţu Modest , Iliffe Thomas
Published: March 2012

Leptochelia Vatulelensis(Crustacea: Tanaidacea), A New Species From Anchialine Caves of the South-Western Pacific

Leptochelia vatulelensisn. sp., discovered on the small islands of Vatulele (Fijian group) and Ouvéa (Loyalty Islands, New Caledonia), is described and illustrated. The new species is distinguished from the others of the"Leptochelia-dubiagroup" (to which it is generally similar) by the following combination of morphological characteristics: (1) the presence of three to four distal setae on the maxilliped basis; (2) merus of pereopods III and IV with only a distosternal seta; (3) endopod of the uropods formed of four (rarely three) articles; (4) males with two (sometimes three) relatively short aesthetascs on the first five articles of the antennular flagellum; (5) male cheliped with a diminished dimorphism; (6) males with a vertical comb-row of setae on the cheliped propodus. Although it inhabits inland, anchialine caves, the new species lacks morphological features that are characteristic of some cave species.
Observations on the Bat Fauna (Mammalia: Chiroptera) of Roşia Montană (Romania)
Authors: Murariu Dumitru , Pop Dorin
Published: March 2012

Observations on the Bat Fauna (Mammalia: Chiroptera) of Roşia Montană (Romania)

The observation and identification of some bat species of the families Rhinolophidae and Vespertilionidae from Roşia Montană led to the completion of the list of the bat fauna, known from this locality, to a number of 12 species. This fact proves a certain state of the ecosystem complex from Roşia Montană, knowing that the bats are good indicators of the biodiversity state of an area. The bat species identified by the authors and added to the species list for Roşia Montană are:Rhinolophus hipposideros, Myotis brandtiiandPipistrellus (=Hypsugo) savii. Rhinolophus hipposiderosis included in the Annex II of the Directive of Habitats, and it is a key species in the National Programme for Bat Monitoring.
“We Never Refer to Ourselves as a Lobby Group Because ‘Lobby Group’ Has a Different Connotation”: Voluntary Police Associations and the Framing of Their Interest Group Work
Authors: Huey Laura , Hryniewicz Danielle
Published: March 2012

The police, like other groups in civil society, have a vested interest in the outcome of government policy deliberations. Collectively, they often attempt to advance policy agendas through several lobbying techniques that suggest that their voluntary associations could be properly understood as interest groups. And yet, there is often ambivalence or a deep reluctance on the part of police organizations to characterize their politicking as interest group work. In the present article, we draw on interviews, media reports and various other materials to elucidate some of the rhetorical strategies used to recast police interest-group work. Further, we explain the reluctance of police leader groups to be seen as overtly political and contrast this to attitudes held by police rank-and-file groups that more openly characterize their interest group work as “lobbying.” The overall goal of this article is to contribute to a surprisingly thin literature on the politics of the police.
Silicon-[18F]Fluorine Radiochemistry: Basics, Applications and Challenges
Authors: Wängler Carmen , Kostikov Alexey , Zhu Jun , Chin Joshua , Wängler Björn , Schirrmacher Ralf
Published: March 2012

Silicon-[18F]fluorine (Si-18F) radiochemistry has recently emerged alongside other unconventional approaches such as aluminum-18F and boron-18F based labeling strategies, reshaping the landscape of modern 18F-radiochemistry. All these novel methodologies are driven by the demand for more convenient 18F-labeling procedures to further disseminate one of the most sophisticated imaging technologies, Positron Emission Tomography (PET). The PET methodology requires special radionuclides such as 18F (one of the most prominent examples) to be introduced into bioactive molecules. Si-18F radiochemistry contributed greatly towards the development of new radiopharmaceuticals for PET imaging. Herein, we describe the radiochemical basics of Si-18F bond formation, the application of Si-18F tracers for PET imaging, and additionally, the inherent chemical intricacies of this methodology.
Response Surface Methodology to Optimize Enzymatic Preparation of Deapio-Platycodin D and Platycodin D from Radix Platycodi
Authors: Li Wei , Zhao Li-Chun , Wang Zi , Zheng Yi-Nan , Liang Jian , Wang Hui
Published: March 2012

In the present work, we reported the enzymatic preparation of deapio-platycodin D (dPD) and platycodin D (PD) optimized by response surface methodology (RSM) from Radix Platycodi. During investigation of the hydrolysis of crude platycosides by various glycoside hydrolases, snailase showed a strong ability to transform deapio-platycoside E (dPE) and platycoside E (PE) into dPD and PD with 100% conversion. RSM was used to optimize the effects of the reaction temperature (35–45 °C), enzyme load (5–20%), and reaction time (4–24 h) on the conversion process. Validation of the RSM model was verified by the good agreement between the experimental and the predicted values of dPD and PD conversion yield. The optimum preparation conditions were as follows: temperature, 43 °C; enzyme load, 15%; reaction time, 22 h. The biotransformation pathways were dPE→dPD3→dPD and PE→PD3→PD, respectively. The determined method may be highly applicable for the enzymatic preparation of dPD and PD for medicinal purposes and also for commercial use.
Subminimal Inhibitory Concentrations of the Disinfectant Benzalkonium Chloride Select for a Tolerant Subpopulation of Escherichia coli with Inheritable Characteristics
Authors: Moen Birgitte , Rudi Knut , Bore Erlend , Langsrud Solveig
Published: March 2012

Exposure of Escherichia coli to a subminimal inhibitory concentration (25% below MIC) of benzalkonium chloride (BC), an antimicrobial membrane-active agent commonly used in medical and food-processing environments, resulted in cell death and changes in cell morphology (filamentation). A small subpopulation (1–5% of the initial population) survived and regained similar morphology and growth rate as non-exposed cells. This subpopulation maintained tolerance to BC after serial transfers in medium without BC. To withstand BC during regrowth the cells up regulated a drug efflux associated gene (the acrB gene, member of the AcrAB-TolC efflux system) and changed expression of outer membrane porin genes (ompFW) and several genes involved in protecting the cell from the osmotic- and oxidative stress. Cells pre-exposed to osmotic- and oxidative stress (sodium chloride, salicylic acid and methyl viologen) showed higher tolerance to BC. A control and two selected isolates showing increased BC-tolerance after regrowth in BC was genome sequenced. No common point mutations were found in the BC- isolates but one point mutation in gene rpsA (Ribosomal protein S1) was observed in one of the isolates. The observed tolerance can therefore not solely be explained by the observed point mutation. The results indicate that there are several different mechanisms responsible for the regrowth of a tolerant subpopulation in BC, both BC-specific and general stress responses, and that sub-MIC of BC may select for phenotypic variants in a sensitive E. coli culture.