bluuebunny/crossref_metadata_2025 huggingface dataset:
Good Practices in Progressing a Smart Well Portfolio
Authors: Lau Hon-Chung
Published: November 2008

Although smart wells have gained acceptance in the industry1–3, the integrated workflow needed to progress a portfolio of smart well opportunities requires systematic attention. In some cases, smart wells fail to materialize not because technologies are not ready but because of lack of participation and integration of relevant disciplines in a timely fashion.

This paper summarizes the good practices used by one operator to progress a portfolio of smart well opportunities in a number of major projects. The smart well workflow is divided into six phases: Identify, Assess, Select, Define, Execute and Operate. The objectives, technical considerations, contribution from various disciplines, key success factors and good practices of these phases are defined and detailed.

A key to successfully progressing smart well opportunities in a project is to identify and work the interfaces between the relevant disciplines. In the first three phases, the project team identifies the opportunities and assesses the feasibility of various smart well options. The optimum smart well solution is then selected through quantification of both the risks and benefits of these options using a multi-disciplinary approach. Quite often smart wells are advocated by one discipline without sufficient buy-in from other disciplines. This often leads to a weak business case and failure to adopt smart wells by the project team. In the Define Phase, attention should be placed on ensuring that smart wells components are compatible with other components in the well, subsea and surface systems. In the Execute Phase, a rigorous QA/QC program is key to successful installation. In the Operate Phase, a Collaborative Work Environment is recommended to bring data, information and people from different locations together to facilitate timely decision making to optimize the value of the asset.

Introduction

In this paper, a smart well is defined as one that consists of both downhole sensing and flow control. Typical downhole sensing devices include permanent pressure and temperature gauges, flowmeter, and distributed temperature sensing (DTS). Other devices include cableless communication and downhole geophones for detecting microseism. Typical downhole controls include interval control valves (ICV) and auto gas-lift valves. Interval control valves can be on/off, multi-positioned, or infinitely variable. They may be actuated by hydraulic or electrical control lines or both. The degree of smartness should be fit-for-purpose and defined in the early stages of a project.

A smart field4–6 usually consists of one or more of the following: smart wells, smart facilities, and an aerial reservoir surveillance program, e.g. 4D seismic. A field becomes smart when information from these technologies can be assessed, evaluated and analyzed by relevant disciplines to make timely decisions to optimize the productivity and recovery of the field. While this paper focuses on smart wells, how smart wells fit into the overall smart field implementation will be discussed.
A New Approach for Optimizing Cement Design to Eliminate Microannulus in Steam Injection Wells
Authors: Shakirah Saidin
Published: November 2008

Over the past few years, several papers have been published discussing the long-term mechanical durability of the cement sheath in steam injection well. Looking at this, the research is continued to find the right process flow in optimizing cement design as a new approach to eliminate microannulus in steam injection well. This process flow is based on previous experiences cementing in steam well. Duri Steam Flood is located in Sumatra, Indonesia was taken as a case study in this research. As we known, changes in downhole stress conditions that occur during the life of a steam injection well are extreme. The stresses in the cement sheath induced by the extreme temperature cycling could result in severe mechanical damage and ultimate failure of the cement sheath, potentially leading to microannulus.

From well life analysis, the result found that the steam well in Duri Steam Flood has 6% risk of cement sheath failure in less than 5 year. Because of this, the research is carried out to find the reason and solution of this failure. Firstly cemented annulus stress simulation is proposed to verify this cement sheath condition. Expanding cement is one of the proposed solutions in this study based on simulation recommendation. The behavior of the cement sheath with recently developed annulus and linear experiment is proposed. Three parts of testing for linear expanding test were conducted. Firstly, test at bottom hole static condition temperature (120 degF) and pressure (1000 psi) curing for 30 days. Then, test at bottom hole static temperature condition curing for 2 days with variation of pressure (1000 psi to 3000 psi) and test at bottom hole static pressure condition curing for 2 days with variation of temperature (100 degF to 300 degF). Magnesium Oxide (MgO) is used as an expansion additive with conventional cement slurry (Class G and 35% BWOC Silica). The concentration used is 2.7% BWOC to 7.0% BWOC. Finally compressive strength tested at bottom hole static pressure with variation of temperature (150 degF to 280 degF) at 24 hours. Therefore, a process guideline is finalized based on last cementing experiences, experiment results and cost analysis to find the most optimize cement slurry in steam injection well.

Introduction

Cementing is a part of well completion process before the well is ready for production for oil or gas from reservoir. It is very important process to make sure the cement job has to fulfill multiple conditions, but its main function is to prevent fluid and gas flow through the annulus by ensuring an impermeable bond and exhibiting sufficient compressive and shear bond strength. The sealing can be affected by various factors: poor mud removal, bad slurry properties and borehole conditions (expose to the change in temperature and pressure as always happen in steam injection well). It is also recognized that the volumetric changes of cement during hydration substantially contribute to these problems.
Preparing a Gas Field Development Plan : Tangga Barat Cluster Gas Project
Authors: Teh Yat Hong , Theseira Keith , Abdul Karim Abdul Hamid , Hashim Naqzatul Shima , Yakob A. Razak , Musa Ahmad Syrhan , Borhan Nor Aisyah , Muhamad Suhana , Sykahar M. Wakif
Published: November 2008

Field development planning is one of the core business processes in the upstream oil and gas industry. Before a discovered field can be developed and its hydrocarbon produced, proper evaluation and planning of the subsurface reservoirs and surface facilities are necessary to ensure that the field development plan is not only economical to undertake, but also flexible enough to cater for any deviation from the original plan during implementation as a result of inherent uncertainties in the reservoirs over the production life span of the field.

This paper describes the approach taken to prepare a Field Development Plan (FDP) for a cluster of gas fields located offshore Peninsular Malaysia. The four gas fields namely Melor, Laho, Tangga and Tangga Barat ("Tangga Barat Cluster" in short) are located within a 25 km radius of each other at a common centre. One common denominator among these fields is the presence of carbon dioxide (CO2) in its reservoirs. The Tangga Barat Cluster fields will be developed with Tangga Barat as the central processing complex, designed for a peak capacity of 440 MMscf/d of raw gas with an initial blended CO2 level of 37 mol % prior to CO2 removal. The raw gas will be processed, pre-treated and CO2 content reduced to below 8 mol % for evacuation to Peninsular Malaysia via an existing infrastructure. The key areas emphasized in the preparation of the field development plan include the business driver, resource assessment, depletion strategy, development concept and selection, managing uncertainties, appraisal requirements, reservoir management, anticipating production problems and disposal of the excess CO2.

Introduction

The Tangga Barat Cluster fields are located about 150 to 170 km northeast of Kertih, Terengganu offshore Peninsular Malaysia (Figure 1). The Tangga Barat Cluster consists of four gas fields; Melor, Laho, Tangga and Tangga Barat. In the vicinity are two producing fields, Resak which is a gas development located about 51 km southwest of the Tangga Barat field and Dulang, an oil development situated about 20 km south of Tangga Barat. The Tangga Barat Cluster fields were discovered from 1980 to 1993; they remain undeveloped due to the presence of CO2 in its reservoirs, the content level of which is beyond the gas specification required for gas sales. Since then, a total of 10 exploration and appraisal wells have been drilled before the final FDP was submitted and approved by PETRONAS, the host authority for upstream oil and gas business in Malaysia.
From Shallow Hazard to Productive Opportunity: Opening a New Gas Play in the North Malay Basin
Authors: Mohd Nasir Mohamed Azlin , Shamsuddin Seri'ainatrah , Bakri Mohd Shah Reza
Published: November 2008

Lawit field operated by ExxonMobil E&P Malaysia (EMEPMI) in the Malay Basin was discovered in 1979. Due to the shallow and unconsolidated nature of the Group-B sands, the sands were considered a potential shallow hazard, thus the initial field development plan implemented in 1997 only targeted the deeper, and major gas bearing Group-D and E reservoirs. After 9 years of production, the major producing reservoirs, particularly the aquifer supported reservoirs, indicated signs of depletion.

As a result of a Lawit full-field study conducted in 2005, the asset level technical team appraised the development opportunity in Group-B reservoirs by re-completion of existing wells that were originally completed in the deeper Group-D and E reservoirs, now depleted, in order to sustain gas production from the field and utilize existing facilities capacity.

This paper will describe the multi-disciplinary Geoscience, Reservoir, and Subsurface Engineering technical work flow and strategies used in the successful development of the first Lawit shallow gas Group-B reservoirs in EMEPMI offshore operations. The assessment included estimates of in-place gas, gas deliverability and recovery, and thorough consideration of completion strategies to mitigate the potential for high sand production. The collaborative effort also resulted in the first successful application of Frac-Pack completion in EMEPMI operations, yielding sustainable and prolific gas production.

Key implications of this successful venture include potential development of the Group-B reservoirs in other EMEPMI operated fields in the Malay Basin.

INTRODUCTION

The Lawit field is a non-associated gas (NAG) producing field in the Malay Basin located offshore Peninsular Malaysia in an average water depth of 60 meters. The field was discovered in May 1979 by the Well 1 wildcat well which encountered multiple gas-bearing reservoirs.

The Lawit structure is a domal anticline with an aerial extent of about 30 square kilometers at its major reservoir level. The field is separated from neighboring Bintang field to the west by a major north - south trending normal fault.

Malay Basin production is primarily from Early to Late Miocene-age clastic reservoirs. These reservoirs often occur in stacked stratigraphic sequences which are grouped and labeled alphabetically. Lawit field accumulations are normally pressured and contain non-associated, lean wet-gases.

Lawit-A is a large manned production, compression and quarters platform. Lawit-A is also a mother platform to two unmanned Satellite Field Development (SFD) platforms, Bintang-A and Bintang-B. These platforms accommodate production from the Bintang field where the gas produced is sent to Lawit-A for processing, then transported to shore.
Long Term Evaluation of an Innovative Acid System for Fracture Stimulation of Carbonate Reservoirs in Saudi Arabia.
Authors: Garzon Francisco Orlando , Solares Jose Ricardo , Ramanathan Venkateshwaran , Franco Carlos Alberto , Al-Marri Hamad Mohammed , Hakami Ibrahim Mohammed
Published: November 2008

Acid Fracturing has been a successful method to stimulate the Khuff Carbonate wells of Saudi Arabia since the beginning of the gas development program. Various types of acid systems including conventional, emulsified and surfactant-based have been used in an attempt to achieve optimum fracture length and conductivity. Acids used for these treatments have been typically formulated with 28-wt% HCl and have been used successfully to increase production from the Khuff carbonates.

Although acid fracture treatments create significant conductivity enhancement in treated wells, their etched fracture length is typically short because of the high speed at which acid spends upon contact with the high temperature reservoir. The quest to increase the effective half-length of the fracture and enhance production led to the search for novel effective technologies capable of achieving this goal. One such technology is the solid acid system which was field tested for the first time in the world in a Saudi Aramco gas producer. The material is pumped as an inert solid, which hydrolyzes and converts to acid when exposed to water and heat resulting in heterogeneous etching and increased conductivity. Among the key factors supporting a field trial of the product was the fact that it offered the prospect of overcoming the traditional challenges that are always associated with acid fracturing such as excessive acid leak-off, shallow acid penetration, fast spending due to the temperature effect and corrosion. However, a solid acid system also reduces the health, safety and environmental (HSE) risk caused by conventional acid exposure to both personnel and production equipment. Placement of this material in the Khuff was a significant challenge due to the high fracture gradients encountered in this complex reservoir. Previous attempts to place proppant in other wells with similar reservoir characteristics resulted in premature screenout. Nevertheless, the first worldwide field trial of the new technology was successfully implemented.

This paper will discuss in detail the design, execution, post-stimulation and the long term results from this first trial. It will also provide conclusions and recommendations on the effectiveness of this novel technology and suggest areas of improvement that will help in promoting a step change in acid fracturing industry worldwide.
Progress towards lightning control using lasers
Authors: Kasparian Jérôme , Ackermann Roland , André Yves-Bernard , Méchain Grégoire , Méjean Guillaume , Prade Bernard , Rohwetter Philipp , Salmon Estelle , Stelmaszczyk Kamil , Yu Jin , Mysyrowicz André , Sauerbrey Roland , Wöste Ludger , Wolf Jean-Pierre
Published: November 2008

Lightning research needs on-demand lightning strikes, because of the random character of natural lightning. Lasers have been proposed as alternatives to the current technique using rocket-pulled wires, because they would expectedly provide more flexibility. However, high-energy, nanosecond lasers cannot provide long connected plasma channels. In contrast, we recently reported the triggering of electric events in thunderclouds using ultrashort laser pulses. Further improvements of the laser pulse sequence and experimental geometry are discussed.
Cost-effectiveness analysis of mechanical thrombectomy in acute ischemic stroke
Authors: Patil Chirag G. , Long Elisa F. , Lansberg Maarten G.
Published: November 2008

Object

Mechanical thrombectomy is increasingly being used for the treatment of large-vessel ischemic stroke in patients who arrive outside of the 3-hour tissue plasminogen activator time window. In this study, the authors evaluated the cost and effectiveness of mechanical thrombectomy compared with standard medical therapy in patients who are ineligible to receive tissue plasminogen activator.

Methods

Clinical outcomes of an open-label study of mechanical thrombectomy were compared with a hypothetical control group with a lower recanalization rate (18 vs 60%) and a lower rate of symptomatic intracranial hemorrhage (0.6 vs 7.8%) than the active treatment group. A Markov cost-effectiveness model was built to compare the health benefits and costs associated with mechanical thrombectomy compared with standard medical therapy. All probabilities, quality-of-life factors, and costs were estimated from the published literature. Univariate sensitivity analyses were performed to assess how variations in model parameters affect health and economic outcomes.

Results

Treatment of acute ischemic stroke with mechanical thrombectomy increased survival time by 0.54 quality-adjusted life years (QALYs), compared with standard medical therapy (2.37 vs 1.83 QALYs), at an increased cost of $6600. This yielded an incremental cost-effectiveness ratio (ICER) of $12,120 per QALY gained, a value generally considered cost-effective. Sensitivity analysis showed that mechanical thrombectomy remained cost-effective (ICER < $50,000 per QALY gained) for all model inputs varied over a reasonable range, except for age at stroke treatment. For patients older than 82 years of age, the treatment was only borderline cost-effective (ICER of $50,000–100,000 per QALY gained).

Conclusions

The treatment of large-vessel ischemic stroke with mechanical thrombectomy appears to be costeffective. These results require validation when data from a randomized, controlled trial of mechanical thrombectomy become available.
Balamuthia mandrillaris meningoencephalitis in an immunocompromised patient
Authors: Kansagra Akash P. , Menon Jayant P. , Yarbrough Chester K. , Urbaniak Klaudia , Waters J. Dawn , Borys Ewa , Jandial Rahul
Published: November 2008

Balamuthia mandrillaris is a rare but increasingly recognized cause of amebic encephalitis, yet it remains poorly understood. The condition is almost universally fatal, and due to diagnostic difficulty, most cases are identified postmortem. The authors report a case of Balamuthia amebic encephalitis in a patient with combined variable immunodeficiency in which a rare antemortem diagnosis was made via brain biopsy. Despite broad-spectrum antimicrobial therapy, the outcome was fatal. Such presentations are challenging, and definitive diagnosis may require biopsy in consultation with a skilled neuropathologist.
Degradation Studies of Polyurethanes Based on Vegetable Oils. Part 1. Photodegradation
Authors: Rus Anika Z. Mohd , Kemp Terence J. , Clark Andrew J.
Published: November 2008

UV-induced photodegradation has been studied of films of polyurethanes synthesised from (renewable) vegetable materials, namely rapeseed and sunflower oils. The techniques utilised were principally IR and UV-visible spectroscopy. UV(B)-photolysis of the cured films gave rise to IR bands in the carbonyl region at ca 1706 cm-1 and a UV band at 310 nm attributed to formation of a quinone methide, an assignment supported by the development of new IR bands at 1595, 1650, and 1695 cm-1 which are typical of this chromophore. In addition, intensification of a band at 1171 cm-1 is attributed to cross-linking of the soft segments in the polymer.

Plots of the growth of the 1706 cm-1 band on irradiation over time showed the usual profile for conversion of CH2 groups to carbonyl: these were normalised against the band at 2900 cm-1 of the polymer to give the carbonyl index (CI). The effect of adding the pigment TiO2 on the CI was monitored. The effect depended strongly on the nature of the TiO2; thus the Degussa P-25 pigment greatly accelerated photodegradation whereas TiO2 coated with a thin layer of silica or alumina, as in Kronos 2220 pigment, conferred photostability on the polymer.

Doping the TiO2 with metal ions markedly affected its behaviour; addition of Mo(VI) made the TiO2 more aggressive while doping with Cr(III) reduced its activity. Addition of the photostabiliser Tinuvin 770 had a dramatic effect in reducing the photo-oxidation of the polyurethanes.
Kinetics and Mechanism of the Oxidation of Some α-Hydroxyacids by Morpholinium Chlorochromate
Authors: Malani Neha , Baghmar Manju , Swami Preeti , Sharma Pradeep Kumar
Published: November 2008

The oxidation of glycollic, lactic, malic and a few substituted mandelic acids by morpholinium chlorochromate (MCC) in dimethylsulfoxide (DMSO) leads to the corresponding oxoacids. The reaction is first order each in MCC and hydroxyacid. The reaction failed to induce the polymerisation of acrylonitrile. The oxidation of α–deuteriomandelic acid shows a primary kinetic isotope effect ( kH/ kD = 5.63 at 298 K) but does not exhibit a solvent isotope effect. The reaction is catalysed by hydrogen ions according to: kobs = a + b[H+]. The oxidation of p-methyl mandelic acid has been studied in 19 different organic solvents and the solvent effect analysed using Kamlet's and Swain's multiparametric equations. A mechanism involving a hydride ion transfer via a chromate ester is proposed.
Vitrification Successfully Preserves Hepatocyte Spheroids
Authors: Magalhães R. , Wang X. W. , Gouk S. S. , Lee K. H. , Ten C. M. , Yu H. , Kuleshova L. L.
Published: November 2008

This is the first report on low-temperature preservation of self-assembled cell aggregates by vitrification, which is both a time- and cost-effective technology. We developed an effective protocol for vitrification (ice-free cryopreservation) of hepatocyte spheroids that employs rapid stepwise exposure to cryoprotectants (10.5 min) at room temperature and direct immersion into liquid nitrogen (-196°C). For this, three vitrification solutions (VS) were formulated and their effects on vitrified-warmed spheroids were examined. Cryopreservation using ethylene glycol (EG)-sucrose VS showed excellent preservation capability whereby highly preserved cell viability and integrity of vitrified spheroids were observed, through confocal and scanning electron microscopy imaging, when compared to untreated control. The metabolic functions of EG-sucrose VS-cryopreserved spheroids, as assessed by urea production and albumin secretion, were not significantly different from those of control within the same day of observation. In both the vitrification and control groups, albumin secretion was consistently high, ranging from 47.57 ± 14.39 to 70.38 ± 11.29 μg/106 cells and from 56.84 ± 14.48 to 71.79 ± 16.65 μg/106 cells, respectively, and urea production gradually increased through the culture period. The efficacy of vitrification procedure in preserving the functional ability of hepatocyte spheroids was not improved by introduction of a second penetrating cryoprotectant, 1,2-propanediol (PD). Spheroids cryopreserved with EG-PD-sucrose VS showed maintained cell viability; however, in continuous culture, levels of both metabolic functions were lower than those cryopreserved with EG-sucrose VS. EG-PD VS, in which nonpenetrating cryoprotectant (sucrose) was excluded, provided poor protection to spheroids during cryopreservation. This study demonstrated that sucrose plays an important role in the effective vitrification of self-assembled cell aggregates. In a broad view, the excellent results obtained suggest that the developed vitrification strategy, which is an alternative to freezing, may be effectively used as a platform technology in the field of cell transplantation.
Ascorbic Acid Increases the Number of Dopamine Neurons In Vitro and in Transplants to the 6-OHDA-Lesioned Rat Brain
Authors: Bagga V. , Dunnett S. B. , Fricker-Gates R. A.
Published: November 2008

The inadequate survival of dopamine neurons following intracerebral transplantation is in part attributed to the generation of reactive oxygen species and subsequent oxidative stress. To address this, we investigated whether the antioxidant ascorbic acid (vitamin C) had any effect on the yields of dopamine neurons derived from E14 rat ventral mesencephalic cells in vitro and in grafts. Following in vitro differentiation in medium containing ascorbic acid at concentrations ranging from 20 to 100 μM, significantly more neurons were immunopositive for the marker of mesencephalic dopamine neurons, tyrosine hydroxylase (TH), when compared to standard differentiation conditions containing no ascorbic acid. Mesencephalic cell suspensions supplemented with 100 μM ascorbic acid were also transplanted into unilateral 6-OHDA-lesioned rats and behavioral rotation was assessed at 2, 4, and 6 weeks posttransplantation. Grafts pretreated with ascorbic acid contained significantly more surviving dopamine neurons compared to nontreated grafts. However, no significant difference in rotation score was observed, with both groups showing a reversal and overcompensation of rotational bias. In addition, no evidence of neurogenesis of nigral dopamine neurons was observed in transplant groups. While the increased number of dopamine neurons observed in our study following ascorbic acid treatment may reflect a selective survival effect, our in vitro results suggest that ascorbic acid may act to increase the number dopamine neurons, both in culture and following transplantation, by stimulating dopaminergic differentiation of neural precursors from the fetal ventral mesencephalon.
Xenotransplantation of Human Umbilical Cord Blood Mononuclear Cells to Rats with D-Galactosamine-Induced Hepatitis
Authors: Álvarez-Mercado Ana I. , Sáez-Lara María J. , García-Mediavilla María V. , Sánchez-Campos Sonia , Abadía Francisco , Cabello-Donayre María , Gil Ángel , Gonzalez-Gallego Javier , Fontana Luis
Published: November 2008

Cord blood is an attractive cell source in regenerative medicine and represents an alternative to bone marrow. The aim of this study was to investigate whether human umbilical cord blood mononuclear (HUCBM) cells might be valuable in hepatic regenerative medicine. HUCBM cells differentiated in vitro into hepatocytes, as suggested by expression of albumin, cytokeratin-18, glutamine synthetase, α-fetoprotein, and cytochrome P450 3A4 at both mRNA and protein levels in a time-dependent fashion. In contrast, the hematopoietic phenotype was gradually lost, as demonstrated by disappearance of CD45 expression. The regenerative potential of HUCBM cells was tested by using a human-to-rat xenotransplant model in which HUCBM cells were intraportally injected into rats with D-galactosamine-induced hepatitis. Liver histology and biochemical markers of hepatic damage were determined. Presence of human cells was detected in blood and liver of both control and D-galactosamine-treated animals. Cell transplantation produced an improvement in both the histological damage and liver function, as demonstrated by plasma values of alkaline phosphatase, γ-glutamyl transferase, lactate dehydrogenase, and total and direct bilirubins. Results obtained suggest that HUCBM cells are capable of hepatic engraftment in this human-to-rat xenotransplant model and that transplantation of HUCBM cells may be a suitable therapy for liver disease.
Core–Shell PbI2@WS2 Inorganic Nanotubes from Capillary Wetting
Authors: Kreizman Ronen , Hong Sung You , Sloan Jeremy , Popovitz‐Biro Ronit , Albu‐Yaron Ana , Tobias Gerard , Ballesteros Belén , Davis Benjamin G. , Green Malcolm L. H. , Tenne Reshef
Published: November 2008

Multiwall WS2 nanotube templates were used as hosts to prepare core–shell PbI2@WS2 nanotubes by a capillary‐wetting method. Conformal growth of PbI2 layers on the inner wall of the relatively wide WS2 nanotubes (i.d. ca. 10 nm) leads to nanotubular structures which were not previously observed in narrow carbon nanotube templates. Image simulation after structural modeling (see picture) showed good agreement with the experimental HRTEM image.

magnified image
Dehydration of THF‐water mixtures using zeolite‐incorporated polymeric membranes
Authors: Varghese J. G. , Kittur A. A. , Kariduraganavar M. Y.
Published: November 2008

Using a solution technique, polymeric composite membranes were prepared by the incorporation of NaY zeolite into chitosan. The resulting membranes were tested for pervaporation separation of water–tetrahydrofuran mixtures in a temperature range of 30–50°C. The effect of membrane swelling on the separation performance was studied by varying the water composition in the feed from 5 to 30 mass %. Pervaporation data demonstrated that both flux and selectivity increased simultaneously with increasing zeolite content in the membrane. This was explained on the basis of enhancement of hydrophilicity, selective adsorption, and establishment of molecular sieving action. It was found that both total flux and flux of water are close to each other, suggesting that the developed membranes are highly selective toward water. The membrane containing the highest loading of zeolite exhibited the highest separation selectivity of 2140 with a substantial water flux of 16.88 × 10−2 kg/(m2 h) at 30°C for 5 mass % of water in the feed. From the temperature dependency of diffusion and permeation data, the Arrhenius activation parameters were estimated. A significant difference was noticed between Epw and EpTHF, EDw and EDTHF values, signifying that membranes developed with higher loading of zeolite exhibited remarkable separation selectivity toward water. The Ep and ED values ranged between 11.69 and 21.23, and 11.21 and 20.72 kJ/mol, respectively. All the membranes exhibited positive ΔHs values, suggesting that the heat of sorption is still dominated by Henry's mode of sorption. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Comparison between the self‐assembling behaviors of PLLA‐PEO‐PLLA triblock copolymers and PLLA‐PEO‐PPO‐PEO‐PLLA pentablock copolymers
Authors: Xiong Xiang Yuan , Li Zi Ling , Tam Kam Chiu , Li Yu Ping , Leng Jin Quan , Chen Hai Qin , Wang Yong
Published: November 2008

Poly(L‐lactic acids) (PLLAs) were grafted to both ends of poly(ethylene oxide) (PEO) to produce biocompatible amphiphilic PLLA‐PEO‐PLLA triblock copolymers. The self‐assembling behaviors of two PLLA‐PEO‐PLLA copolymers in aqueous solutions were examined by Dynamic Light Scattering and Transmission Electron Microscopic techniques. PLLA‐PEO‐PLLA formed spherical micelles, whereas PLLA‐PEO‐PPO‐PEO‐PLLA pentablock copolymers were reported to produce vesicles. It is believed that the PPO segment within the PLLA‐PEO‐PPO‐PEO‐PLLA pentablock copolymers has a dominant role in the formation of vesicles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Regional scale prediction of the onset phase of the Indian southwest monsoon with a high‐resolution atmospheric model
Authors: Bhaskar Rao Dodla Venkata , Srinivas Desamsetti , Bishoyi Ratna Satyaban
Published: November 2008

A nonhydrostatic atmospheric model with a resolution of 30 km is used to make predictions of the rainfall during the onset phase of the southwest monsoon (SWM) of 2003. Model predictions of the pentad rainfall time series indicate good predictions up to lead time of 5 days. The correlation coefficients (CCs) between the model‐predicted and observed rainfall at different locations, representative of the five homogeneous regions of SWM rainfall, over the Indian subcontinent show correlations significant at 90% level up to 5 days lead time with values above 0.32. The spatial distribution of the model‐predicted pentad rainfall show an advancement of the Arabian Sea and the Bay of Bengal branches of SWM over the Indian subcontinent up to 5 days lead time. Copyright © 2008 Royal Meteorological Society
Species‐specificity of ethylene glycol‐induced developmental toxicity: toxicokinetic and whole embryo culture studies in the rabbit
Authors: Carney Edward W. , Tornesi Belen , Markham Daniel A. , Rasoulpour Reza J. , Moore Nigel
Published: November 2008

High‐dose gavage exposure to ethylene glycol (EG) is teratogenic in rats, but not rabbits. To investigate the reason for this species difference, toxicokinetic and whole embryo culture (WEC) studies were conducted in gestation day 9 New Zealand White rabbits, and the data compared to very similar data previously generated in pregnant rats. In the toxicokinetic study, maximal levels of unchanged EG in rabbits were comparable to those reported for rats. However, maximal levels of EG's teratogenic metabolite, glycolic acid (GA), in rabbit maternal blood and embryo were only 46% and 10% of the respective levels in rats. The toxicokinetic profile suggested that the lower GA levels in rabbits were due to a slower rate of maternal metabolism of EG to GA, slow uptake of GA into the yolk sac cavity fluid which surrounds the embryo, and negligible transfer via the visceral yolk sac (VYS) placenta. In the WEC study, exposure of rabbit conceptuses to high concentrations (≤12.5 mM) of GA was without effect, which contrasts with reported effects in rat WEC at ≥3 mM. Overall, these data implicate toxicokinetics as an important factor underlying the species difference, although intrinsic insensitivity of the rabbit embryo might also be involved. Integration of these findings with published human data suggest that the rabbit is the more relevant model for human EG exposure, based on the negligible role of the rabbit VYS in placental transfer (humans lack a VYS) and similar rates of EG metabolism and extraembryonic fluid turnover. Birth Defects Res (Part B) 2008. © 2008 Wiley‐Liss, Inc.
An evaluation of exposure metrics in an epidemiologic study on radio and television broadcast transmitters and the risk of childhood leukemia
Authors: Schmiedel Sven , Brüggemeyer Hauke , Philipp Johannes , Wendler Jost , Merzenich Hiltrud , Schüz Joachim
Published: November 2008

Electric field strength values calculated by wave propagation modeling were applied as an exposure metric in a case–control study conducted in Germany to investigate a possible association between radio frequency electromagnetic fields (RF‐EMF) emitted from television and radio broadcast transmitters and the risk of childhood leukemia. To validate this approach it was examined at 850 measurement sites whether calculated RF‐EMF are an improvement to an exposure proxy based on distance from the place of residence to a transmitter. Further, the agreement between measured and calculated RF‐EMF was explored. For dichotomization at the 90% quantiles of the exposure distributions it was found that distance agreed less with measured RF‐EMF (Kappa coefficient: 0.55) than did calculated RF‐EMF (Kappa coefficient: 0.74). Distance was a good exposure proxy for a single transmitter only which uses the frequency bands of amplitude modulated radio, whereas it appeared to be of limited informative value in studies involving several transmitters, particularly if these are operating in different frequency bands. The analysis of the agreement between calculated RF‐EMF and measured RF‐EMF showed a sensitivity of 76.6% and a specificity of 97.4%, leading to an exposure misclassification that still allows one to detect a true odds ratio as low as 1.4 with a statistical power of >80% at a two‐sided significance level of 5% in a study with 2,000 cases and 6,000 controls. Thus, calculated RF‐EMF is confirmed to be an appropriate exposure metric in large‐scale epidemiological studies on broadcast transmitters. Bioelectromagnetics 30:81–91, 2009. © 2008 Wiley‐Liss, Inc.
Diffusion in Confined Geometries
Authors: Burada P. Sekhar , Hänggi Peter , Marchesoni Fabio , Schmid Gerhard , Talkner Peter
Published: November 2008

Diffusive transport of particles or, more generally, small objects, is a ubiquitous feature of physical and chemical reaction systems. In configurations containing confining walls or constrictions, transport is controlled both by the fluctuation statistics of the jittering objects and the phase space available to their dynamics. Consequently, the study of transport at the macro‐ and nanoscales must address both Brownian motion and entropic effects. Herein we report on recent advances in the theoretical and numerical investigation of stochastic transport occurring either in microsized geometries of varying cross sections or in narrow channels wherein the diffusing particles are hindered from passing each other (single‐file diffusion). For particles undergoing biased diffusion in static suspension media enclosed by confining geometries, transport exhibits intriguing features such as 1) a decrease in nonlinear mobility with increasing temperature or also 2) a broad excess peak of the effective diffusion above the free diffusion limit. These paradoxical aspects can be understood in terms of entropic contributions resulting from the restricted dynamics in phase space. If, in addition, the suspension medium is subjected to external, time‐dependent forcing, rectification or segregation of the diffusing Brownian particles becomes possible. Likewise, the diffusion in very narrow, spatially modulated channels is modified via contact particle–particle interactions, which induce anomalous sub‐diffusion. The effective sub‐diffusion constant for a driven single file also develops a resonance‐like structure as a function of the confining coupling constant.
Dopamine's role in social modulation of infant isolation‐induced vocalization: II. Maternally modulated infant separation responses are regulated by D1‐ and D2‐family dopamine receptors
Authors: Muller Jeff M. , Moore Holly , Myers Michael M. , Shair Harry N.
Published: November 2008

Mammalian infant behavior directed toward caregivers is critical to survival and may play a role in establishing social bonds. Most mammalian infants vocalize when isolated. Rat pups vocalize at a higher rate when isolated following an interaction with an adult female than after an interaction with littermates, a phenomenon termed maternal potentiation. We previously reported that the D2 receptor family agonist quinpirole disrupts maternal potentiation at a dose that does not alter vocalization rate following contact with littermates. Here we further examine the role of dopamine in maternal potentiation by testing effects of both D1 and D2 receptor family ligands, alone and in combination, on maternal potentiation. We tested the drugs' effects on isolation vocalization subsequent to littermate contact and then another isolation preceded by a brief “reunion” period of exposure either to the anesthetized dam or a handling‐only “pickup” condition. D2 receptor stimulation blocked the increase in vocalizations following reunion with the dam. The D2 agonist effect in the dam‐reunion condition was much larger than its small effect in the pickup condition, providing further evidence that D2 receptors exert a selective modulation of maternal potentiation. On the other hand, systemic administration of the D1 agonist SKF81297 reduced isolation vocalizations nonspecifically, across all the experimental conditions. Finally, the D1 and D2 receptor dual antagonist, alpha‐flupenthixol, increased isolation vocalizations and disrupted potentiation, but at doses that also inhibited locomotion. We conclude that D2 receptor family activation has a more selective effect of disrupting maternal potentiation than D1 receptor family activation. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 51: 158–172, 2009
Chemospecific Allylation and Domino Metathesis of 7‐Oxanorbornenes for Skeletal and Appendage Diversity
Authors: Ikoma Minoru , Oikawa Masato , Sasaki Makoto
Published: November 2008

We report a synthetic strategy for skeletally diverse heterocycles featuring appendage diversity based on a tandem Ugi/Diels–Alder reaction followed by domino metathesis. An associating effect of the amide carbonyl functionality to the ruthenium metal center is proposed in order to account for the difference in the metathesis yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Aminophosphonic Acids and Aminobis(phosphonic acids) as Potential Inhibitors of Penicillin‐Binding Proteins
Authors: Beck Joséphine , Gharbi Sonia , Herteg‐Fernea Adriana , Vercheval Lionel , Bebrone Carine , Lassaux Patricia , Zervosen Astrid , Marchand‐Brynaert Jacqueline
Published: November 2008

Aminophosphonic acids and aminobis(phosphonic acids) have been prepared by the alkylation of Schiff bases with methyl bromoacetate or ethyl acrylate. Other pathways, like the modified Pudovik reaction and Kabachnik–Fields reaction, have been considered for the synthesis of the α‐phosphonic bioisoster of aminocitrate. Partial or complete deprotection of the phosphonate ester have been realised by either acidic hydrolysis or by treatment with trimethylsilyl bromide. Evaluation against penicillin‐binding proteins has shown that our compounds are modest inhibitors of class A β‐lactamases, but have an interesting activity against R39 (D,D‐peptidase/carboxypeptidase). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
On the Involvement of Palladium Nanoparticles in the Heck and Suzuki Reactions
Authors: Tsvelikhovsky Dmitry , Popov Inna , Gutkin Vitaly , Rozin Alina , Shvartsman Azariya , Blum Jochanan
Published: November 2008

We describe two different pathways by which palladium‐catalyzed Heck and Suzuki coupling reactions take place. When sol–gel entrapped palladium acetate was used as a catalyst, the reactions proceed by the formation of metallic nanoparticles. Such particles were already formed during the immobilization of the palladium salt. Upon application of palladium derivatives of proline, tyrosine, or alanine, either in their homogeneous or in their sol–gel entrapped version, no Pd0 particles could be detected, even when the couplings were carried out in boiling mesitylene (161 °C) or during prolonged reaction periods (48 h). The reactions in the presence of the amino acid derivatives proceeded at a higher rate than those by the entrapped palladium acetate. The existence of palladium nanoparticles was investigated with the aid of high‐resolution scanning transmission electron microscopy equipped with energy dispersive X‐ray spectroscopy, as well as by X‐ray photoelectron spectroscopy.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Effect of elevated temperatures and cooling regimes on normal strength concrete
Authors: Bingöl A. Ferhat , Gül Rüstem
Published: November 2008

The compressive strength of normal strength concrete at elevated temperatures up to 700∘C and the effect of cooling regimes were investigated and compared in this study. Thus, two different mixture groups with initial strengths of 20 and 35 MPa were produced by using river sand, normal aggregate and portland cement. Thirteen different temperature values were chosen from 50 to 700∘C. The specimens were heated for 3 h at each temperature. After heating, concretes were cooled to room temperature either in water rapidly or in laboratory conditions gradually. The residual strengths were determined by an axial compressive strength test. Strength and unit weight losses were compared with the initial values. Throughout this study, ASTM and Turkish Standards were used. It was observed that concrete properties deteriorated with the heat; however, a small increase in strength was observed from 50 to 100∘C. Strength loss was more significant on the specimens rapidly cooled in water. Both concrete mixtures lost a significant part of their initial strength when the temperature reached 700∘C. Copyright © 2008 John Wiley & Sons, Ltd.
Efficacy of diagnostic upper node evaluation during (salvage) laryngectomy for supraglottic carcinoma
Authors: Pennings Ronald J. E. , Marres Henri A. M. , den Heeten Annemarie , van den Hoogen Frank J. A.
Published: November 2008

Background.

The effectiveness of selective upper node dissection or inspection during laryngectomy for supraglottic squamous cell carcinoma was evaluated. These diagnostic procedures aimed to cause less morbidity than elective neck dissection in patients with a clinically N0 neck.

Methods.

In 93 patients, 166 clinically N0 necks (73 bilateral and 20 contralateral) were evaluated. Lymph nodes at levels II and III were inspected or dissected and directly sent in for frozen section histopathology. This way, occult neck metastases were identified and treated by neck dissection.

Results.

Occult neck metastases were identified in 19% of the examined necks (31/166). Regional recurrence rate in the postoperative N0 necks was 0%, and 10% in the postoperative N+ necks.

Conclusions.

Selective upper node dissection and inspection during laryngectomy reduced the need for an elective neck dissection with its morbidity in the clinically N0 neck. In addition, it selects the patients who need such extensive treatment. © 2008 Wiley Periodicals, Inc. Head Neck, 2009.
Phosphorus in groundwater—an overlooked contributor to eutrophication?
Authors: Holman I. P. , Whelan M. J. , Howden N. J. K. , Bellamy P. H. , Willby N. J. , Rivas‐Casado M. , McConvey P.
Published: November 2008

This paper presents the first international assessment of phosphorus concentrations in groundwater, using data from the Republic of Ireland, Northern Ireland, Scotland, England and Wales. Phosphorus is considered to be the main limiting nutrient in most freshwater ecosystems. Controlling phosphorus inputs is thus considered the key to reducing eutrophication and managing ecological quality. Very little attention has been paid to evaluating transfers via groundwater due to the long‐held belief that adsorption and metal complex formation retain the majority of potentially mobile phosphorus. In each country, ecologically‐important phosphorus thresholds are exceeded in a significant number of groundwater samples. The relative contributions of potential sources for these elevated concentrations are currently unclear but there is evidence to suggest that they are at least partly anthropogenic. The results suggest that groundwater P concentrations are such that they may be a more important contributor to surface water phosphorus than previously thought. Copyright © 2008 John Wiley & Sons, Ltd.
Core mutations in patients with acute episodes of chronic HBV infection are associated with the emergence of new immune recognition sites and the development of high IgM anti‐HBc index values
Authors: Alexopoulou Alexandra , Baltayiannis Gerassimos , Eroglu Cafer , Nastos Theodoros , Dourakis Spyros P. , Archimandritis Athanasios J. , Karayiannis Peter
Published: November 2008

Acute exacerbations in HBeAg negative patients with chronic hepatitis B virus (HBV) infection are invariably associated with concurrent increases in the index of IgM class antibodies against the core protein (anti‐HBc) of the virus. This study aimed to investigate whether this was related to the clearance of variants from the quasispecies pool and the appearance of new ones, with aminoacid substitutions in well recognized B‐cell epitopes. In this study, 5 HBeAg negative patients (A to E) with 13 sequential serum samples (A1‐A2, B1‐B2‐B3, C1‐C2, D1‐D2‐D3, E1‐E2‐E3) were investigated after amplification of the entire core encoding region followed by cloning/sequencing studies. The sequences at different time points were compared with those from a single HBeAg positive patient with no apparent acute exacerbations. The results from sequence comparison showed that virus variants emerged in all (A2, B3, C2, D3, E2, and E3) but two (B2 and D2) subsequent sera with amino‐acid substitutions affecting B‐cell epitopes. It is concluded that the rise in the values of IgM anti‐HBc may be attributed to the alteration of the antigenic epitopes leading to new antibody production in the majority of the cases. However, it appears that increases in IgM anti‐HBc indexes in a few cases may relate to other possible mechanisms which are discussed. J. Med. Virol. 81:34–41, 2009. © 2008 Wiley‐Liss, Inc.