bluuebunny/crossref_metadata_2025 huggingface dataset:
New thallium diphosphates Tl2
Me(H2P2O7)2 · 2 H2O, Me = Mg, Mn, Co, Ni and Zn. Synthesis, single crystal X-ray structures and powder X-ray structure of the Mg phase
Authors: El Bali Brahim , Capitelli Francesco , Alaoui Aziz Tahiri , Lachkar Mohammed , da Silva Iván , Alvarez-Larena Angel , Piniella Juan F.
Published: August 2008

Crystals of thallium dihydrogendiphosphate Tl2
Me(H2P2O7)2 · 2 H2O (Me = Mg (1), Mn (2), Co (3), Ni (4) and Zn (5)), have been synthesized and analyzed by powder X-ray diffractometry (Mg phase) and single crystal X-ray diffractometry (other phases). They resulted to be isostructural within triclinic group P-1, with the following unit-cell parameters: a = 6.9620(1), b = 7.3635(1), c = 7.7713(1) Å, α = 81.8014(5), β = 70.8597(6), γ = 86.1373(7)°, V = 372.44(8) Å3
(1); a = 6.9577(6), b = 7.4745(6), c = 7.8248(7) Å, α = 80.723(2), β = 71.912(1), γ = 85.661(1)°, V = 381.62(6) Å3
(2); a = 6.9767(7), b = 7.3634(7), c = 7.7690(7) Å, α = 81.421(2), β = 71.114(2), γ = 86.424(2)°, V = 373.36(6) Å3
(3); a = 6.9658(7), b = 7.3079(7), c = 7.7016(7) Å, α = 81.801(2), β = 71.185(2), γ = 86.528(2)°, V = 367.27(6) Å3
(4) and a = 6.9628(7), b = 7.3625(7), c = 7.7401(8) Å, α = 81.590(2), β = 71.441(2), γ = 86.323(2)°, V = 372.04(6) Å3
(5).

Me is octahedrally coordinated by two water molecules and four oxygen atoms belonging to two different diphos phate groups. Thallium cations make up interactions with oxygen atoms within Van der Waals coordination sphere, making up irregular coordination polyhedra. The framework of the present compounds can be described as a three-dimensional framework made from vertex-sharing polyhedra. The basic unit is the [Me(H2P2O7)2 · 2 H2O] moiety, which displays a crystallographic Ci symmetry, with the Me cation on the inversion centre. Such units are held together by an intricate scheme of Tl…O interactions; hydrogen bonds complete the network.
The crystal structure of “bis(trimethyltin)-1,3,4-thiadiazole-2,5-dithiolate” – different bonding of the two trimethyltin groups
Authors: Engel Günther , Mattern Günter
Published: August 2008

[(CH3)3Sn]2S2(C2N2S) is monoclinic, space group P21
/c, a = 10.492(5), b = 12.257(6), c = 12.691(6) Å, β
= 95.86(1)°. The zigzag chain structure of the coordination polymer can be derived by the structure correlation method. The starting point is a monomolecular symmetric bis(trimethyltin)-1,3,4-thiadiazole-2,5-dithiolate (Me3SnS)2 (C2N2S): The first of the Me3SnS moieties, bound to the atom C5 of the heterocyclus, remains tetrahedral, whereas the other, bound to C2, is transformed through the N3 atom of the neighbouring ring to a trigonal bipyramid S···(Me3Sn)···N. The three C atoms and the Sn atom of this Me3Sn group are nearly coplanar and form the equatorial plane. With the N3 atom of the starting molecule, an equivalent linking to the other neighbour takes place. The resultant plane ribbons run parallel to the crystallographic b-axis. The analysis of the bond distances and angles reveals that the regular trigonal bipyramid almost exactly represents the transition state along a chemical reaction pathway for a nucleophilic SN2 displacement at tetrahedrally coordinated tin.
Crystal and molecular structures of three 2-substituted 4-methyloxan-4-ol derivatives studied by X-ray crystallography and by PM6 calculations
Authors: Zukerman-Schpector Julio , Dos Santos Alcindo A. , Macedo Alexandra , Wendler Edison P. , Brito Gilmar A. , Tiekink Edward R. T.
Published: August 2008

The conformational features of three 2-substituted 4-methyloxan-4-ol (tetrahydropyran) derivatives were investigated by single crystal X-ray crystallographic studies and the geometries were optimized using semi-empirical PM6 methods. The tetrahydropyran ring in each of (I)–(III) adopts a chair conformation with their hydroxyl groups occupying equatorial, axial and axial positions, respectively. The strongest hydrogen bonding interactions apparent in each of the respective crystal structures, as judged from distance and angle considerations, involve the ring-bound O2-hydroxyl group and tetrahydropyran ring oxygen atom. These hydrogen bonds lead to a supramolecular chain with a linear topology in each case but generated by glide symmetry in (I) and (II), and 21-screw symmetry in (III). In the latter, a two dimensional array constructed by O—H…O bonding is found leading to undulating layers. Despite the absence of additional O—H…O hydrogen bonding sites, two dimensional arrays are also generated in each of (I) and (II), but this time mediated by C—H…O contacts that lead to flat layers. The theoretical structures for each of (I) and (III) differ from their respective experimental structures in terms of the relative orientation of the aromatic substituent. By contrast, for (II), there is close agreement between the experimental and theoretical structures. (I) C12H16O2, monoclinic, Cc, a = 18.7887(8), b = 6.0634(2), c = 10.4178(4) Å, β = 116.945(7)°, V = 1057.99(10) Å3, Z = 4, R
1 = 0.029; (II) C13H18O3, orthorhombic Pc21n, a = 9.3664(17), b = 10.0472(18), c = 12.240(2) Å, V = 1151.9(3) Å3, Z = 4, R
1 = 0.037; (III) C13H18O4, orthorhombic P212121, a = 9.814(3), b = 9.966(2), c = 11.845(2) Å; V = 1158.5(5) Å3, Z = 4, R
1 = 0.079.
A comparative study of crystal structure of a Cu(II) dicyanamide compound determined independently from X-ray powder- and single-crystal analyses
Authors: Chakraborty Santu , Ghosh Soumen , Mal Dasarath , Koner Subratanath , Mukherjee Alok Kamur
Published: August 2008

The dicyanamido diethelenetriamine copper (II) compound, C8H13CuN9 (I), has been synthesized, and structurally characterized independently using X-ray powder- and single-crystal diffraction data. The direct methods program package EXPO-2004 has been used for structure solution from laboratory powder diffraction data. Intermolecular N—H···N hydrogen bonds in (I) generate R2
2(16) rings, which are fused forming molecular columns propagating along the [100] direction. Further linking of parallel columns through N—H···N hydrogen bonds results into a three-dimensional supramolecular network.
Metrical Subdivision Results in Subjective Slowing of the Beat
Authors: Repp Bruno H.
Published: August 2008

FOUR EXPERIMENTS INVESTIGATED whether metrical subdivision affects perceived beat tempo. In Experiment 1, musically trained participants tapped in synchrony with the beat of an isochronous pacing sequence and continued tapping the beat after the sequence stopped. Continuation tapping was slower when the pacing beat was subdivided than when it was not. Experiment 2 found the same effect when the subdivisions during synchronization were self-generated. The effect was neutralized, however, when subdivisions were tapped during continuation. In Experiment 3, an effect of subdivision was found in a purely perceptual tempo judgment task. Experiment 4 tested musicians and nonmusicians in matched perception and reproduction tasks. Musicians showed the expected effect of subdivision in both tasks, whereas nonmusicians showed a larger effect in reproduction but a smaller effect in perception. Overall, the findings suggest that subdivided inter-beat intervals are subjectively longer than empty intervals, in agreement with the "filled duration illusion" in psychophysics.
Memory for Verbal and Visual Material in Highly Trained Musicians
Authors: Jakobson Lorna S. , Lewycky Samantha T. , Kilgour Andrea R. , Stoesz Brenda M.
Published: August 2008

INTEREST IN STUDYING THE EFFECTS of extensive music training on nonmusical perceptual and cognitive abilities has grown in recent years. Here, we present evidence that formal music instruction is associated with superior verbal and visual memory. Participants included 15 highly trained pianists and 21 individuals with little or no formal music training. The groups were comparable in terms of age, gender distribution, and socioeconomic status. Musicians showed superior immediate and delayed recall of word lists and greater use of a semantic clustering strategy during initial list-learning than nonmusicians. They also exhibited superior learning, delayed recall, and delayed recognition for visual designs. Group differences in delayed free recall of both words and designs persisted after controlling statistically for estimated Full Scale IQ. These results suggest that extensive music training is associated with a generalized enhancement of auditory and visual memory functions.
Hypocortisolemic clamp unmasks jointly feedforward- and feedback-dependent control of overnight ACTH secretion
Authors: Iranmanesh Ali , Veldhuis Johannes D
Published: August 2008

Background

ACTH secretion is under hypothalamic stimulatory (feedforward) and adrenal inhibitory (feedback) control.

Hypothesis

Assessment of overnight ACTH secretion during a hypocortisolemic clamp will permit the estimation of changing feedforward and feedback.

Subjects

Seven healthy men.

Interventions

An oral dose of placebo (PLAC), metyrapone (METY, 3 g), or ketoconazole (KTCZ, 1.2 g) was given at midnight (MN) to block glucocorticoid synthesis. Plasma ACTH was sampled every 10 min (MN to 0800 h).

Analysis

Variable-waveform deconvolution analysis of ACTH secretion and approximate entropy (ApEn) analysis of pattern regularity.

Results

Compared with PLAC, administration of METY and KTCZ reduced morning cortisol concentrations by ≥77 and 54% respectively (P<0.001). Hypocortisolemia elevated pulsatile ACTH secretion by 8.2- (METY) and 5.3-fold (KTCZ; both P<0.001). Basal ACTH secretion rose by 3.4-fold under METY-induced cortisol depletion (P=0.020). ACTH secretory-burst shape and half-life were stable. ApEn of ACTH release declined overnight (P=0.021) and with the drug (P=0.001), denoting enhanced feedforward coordination.

Conclusion

The combined data predict overnight amplification and coordination of hypothalamic feedforward drive onto ACTH release. Therefore, disruption of either mechanism might contribute to clinical pathophysiology, such as late-day elevations of cortisol output in fasting, alcoholism, depression, or aging.
The first 12 years of history of Hungarian lung transplantations
Authors: Czebe Krisztina , Csiszér Eszter , Lang György , Jaksch Peter , Klepetko Walter
Published: August 2008

Az első magyar beteg tüdőtranszplantációja óta 12 év telt el. Magyarországon kicsiny, de lelkes orvoscsoport dolgozik azon, hogy a tüdőátültetés egyre több magyar állampolgár részére könnyen elérhető, evidens terápiás eljárássá váljék. A műtét indikációját végstádiumú, a tüdő vascularis rendszerét vagy parenchymáját érintő megbetegedések képezik, miután a konzervatív terápiás lehetőségek már kimerültek. Jelenleg hazánkban a tüdőtranszplantáció még nem bevezetett műtéti eljárás. Az elmúlt 12 év során (1996 és 2007 decembere között) 64 magyar betegnél végzett tüdőátültetést a Klepetko professzor által vezetett munkacsoport (Vienna Lung Transplant Group) a bécsi sebészeti klinikán. Betegeinknél a következő alapbetegségek miatt került sor transzplantációra: cisztás fibrosis (22), idiopathiás tüdőfibrosis (18), primer pulmonalis hypertonia (8), lymphangioleiomyomatosis (5), emphysema (4) és egyéb betegségek (7 esetben). A 64 betegnél összesen 68 transzplantáció történt. Négy esetben retranszplantációra került sor. A műtéti technika kétoldali teljes tüdő- (33), kétoldali lebenytranszplantáció (18), egyoldali tüdőtranszplantáció (13), szív-tüdő együttes átültetése (2) és split tüdőtranszplantáció (2) volt. Egy fiatal recipiens esetében élő donoros lebenytranszplantáció történt. A betegek átlagéletkora a műtét idején 33,3 év (14 és 58 év között) volt. A 64 transzplantált közül 48-an vannak jelenleg életben.
The use of Integra “artificial skin, dermal regeneration template” and the reverse radial forearm fasciocutaneous flap in the primary reconstruction of a septic hand injury
Authors: Halmy Csaba , Hábel Tamás , Pesthy Pál , Nádai Zoltán , Juhász Zsuzsanna , Deé Jolán , Tóth Márta
Published: August 2008

Elhanyagolt szeptikus kézsérülés következtében nekrotizált kézháti bőr és extensorapparátus miatt a szerzők reverz radiális lebennyel és egy szervezetbe beépülő, mesterséges bőrrel végeztek rekonstrukciót.
Esetbemutatás:
Az eset bemutatásával beszámolnak az Integra „mesterséges bőr, irha-újraképződési minta” első hazai alkalmazásáról. Az Integra mesterséges bőr a kézhát radiális lebeny által nem fedett területén, illetve az alkari adóterületen került alkalmazásra. Az Integra beépülését követően a külső szilikonréteget eltávolítva rácsplasztikára került sor.
Következtetés:
Az adóterületen az Integra 100%-ban, a mesh graft 99%-ban, a kézháton mindkettő 90%-ban tapadt meg, jó funkcionális és esztétikai eredményt biztosítva.
Hyperinsulinemic hypoglycemia in adults. Case reports and a short review
Authors: Kovács Erzsébet , Németh Hajnalka , Pásztor Éva , Pfliegler György
Published: August 2008

A nem insulinoma eredetű tartós (perzisztáló) hyperinsulinaemiával járó hypoglykaemia oka a felnőttek körében ritkán előforduló nesidioblastosis. A nesidioblastosis hátterében álló inzulinszekréciós zavar molekuláris eltéréseken alapul. Morfológiailag különböző pancreassziget-, illetve béta-sejt-eltérések jellemzik, az inzulinhiperszekréció hátterében azonban körülhatárolható térfoglalás nem mutatható ki. A diagnózis alappillére az alacsony vércukorszint, a normoglykaemia intravénásan alkalmazott glükóz adásával történő fenntarthatósága, illetve az emelkedett inzulin- és C-peptid-szint. A hormontermelő tumor kizárásához mind invazív, mind nem invazív képalkotó módszerek szükségesek. A tartós, illetve ismétlődő hypoglykaemia káros hatásai gyógyszeres és/vagy sebészi kezeléssel előzhetők meg.
Esetismertetés:
A szerzők két betegük esetét ismertetik, akiknél felnőttkorban jelentkeztek a súlyos tünetekkel járó hypoglykaemiás epizódok. Nőbetegük „klasszikus” hypoglykaemiás tünetei 34 éves korban léptek fel: izzadás, szédülés, remegés, idegesség, illetve életveszélyes neuroglycopeniás jelek. Második, férfi betegük 22 éves, akinek fő panasza a hypoglykaemia ritka és szokatlan tünete, a nagyfokú éhségérzet mellett jelentkező puffadás volt. Az éhezési próbák mindkét esetben pozitívak voltak, vagyis hypoglykaemiás tünetek miatt fel kellett azokat függeszteni. Az inzulin- és a C-peptid-szintek magasak voltak, vénás inzulinszint-meghatározás az a. lienalis több pontjából és a képalkotó eljárások (komputertomográfia, mágneses rezonancia, pozitronemissziós tomográfia, angiográfia) nem tudtak igazolni térfoglalást. Az adatok alapján – szövettan hiányában is – a legvalószínűbb a felnőttkori nesidioblastosis diagnózisa. Diazoxid adásával mindkét esetben majdnem teljes tünetmentességet értek el, és neuroglycopeniás esemény a kezelés kezdete óta nem fordult elő.
Következtetések:
Ismeretlen eredetű hypoglykaemia esetén, ha a képalkotó eljárásokkal nincs körülírt képlet, a laboratóriumi adatok viszont egyértelműen emelkedett inzulinszekrécióra utalnak, gondolni kell nesidioblastosis lehetőségére. A sebészi beavatkozás veszélye pancreaselégtelenség éppúgy lehet, mint a betegség fennmaradása a hasnyálmirigy reszekciója miatt. Diazoxid adásával viszont tartós tünetmentesség érhető el ezen ritka kórképben, ezért érdemes elsőként ezt megkísérelni.
Late Permian (Lopingian) gastropods from the Qubuerga Formation at the Qubu section in the Mt. Everest (Qomolangma) Region, Southern Tibet (Xizang), China
Authors: Hua-Zhang Pan , Shu-Zhong Shen
Published: August 2008

Late Permian gastropod fauna in the Mt. Everest (Qomolangma) region, southern Tibet (Xizang), China is poorly known. This paper describes a small gastropod fauna collected by one of the authors (SSZ) from the upper part of the Qubuerga Formation at the Qubu section. The section is located at about 30 km north of Mt. Everest (Fig. 1). Although a limited number of specimens is available, the fauna is more diverse than all previously reported gastropod faunas (e.g., Yu, 1975) from southern Tibet. Description of the gastropod fauna in the Mt. Everest region adds significant data for understanding the distribution of gastropods during the Late Permian and the paleobiogeographic relationship between the Himalayan and Tethyan regions.
Permian colonial rugose corals from the Wrangellian Terrane in Alaska
Authors: Stevens Calvin H.
Published: August 2008

Wrangellia was one of the first described and probably the most widely known of the North American Cordilleran terranes. On the basis of Triassic stratigraphy (Jones et al., 1977) and paleomagnetism (Hillhouse, 1977), the name Wrangellia was proposed for large areas of outcrop in Alaska, British Columbia, and Oregon (Fig. 1).
New Eocene hydrocarbon seep decapod crustacean (Anomura: Galatheidae: Shinkaiinae) and its paleobiology
Authors: Schweitzer Carrie E. , Feldmann Rodney M.
Published: August 2008

A new decapod crustacean species,Shinkaia katapsyxis, is reported from the Eocene Humptulips Formation of western Washington, USA. The specimens were collected from a hydrocarbon seep deposit that has been well-documented and contains a well-described molluscan fauna. The new occurrence extends the geologic range of the genusShinkaiaBaba and Williams, 1998, and subfamily Shinkaiinae Baba and Williams, 1998, into the Eocene from its only other known occurrences in hydrothermal vent environments in the Pacific Ocean. The range extension of an extant decapod genus into the Eocene is not uncommon and adds to the evidence that the Decapoda may be unusually resistant to extinctions and are distinctly conservative evolutionarily.
The Texture of Acidized Fracture Surfaces: Implications for Acid Fracture Conductivity
Authors: Malagon C. , Pournik M. , Hill A. D.
Published: August 2008

In an acid-fracturing treatment, fracture conductivity is created by differential etching of the fracture surface by the acid; without nonuniform dissolution along the fracture face, the fracture will close after pumping ceases, and little lasting conductivity will be created. Despite this critical role of differential etching in the creation of fracture conductivity, little is known about the texture of the fracture surface created during acid fracturing or about the dependence of this texture on the acidizing conditions. To study this important aspect of the acid-fracturing process, we developed a new surface profilometer to measure the surface profile of a rock sample accurately and rapidly and used the instrument to characterize fracture surfaces after acidizing.

The profilometer measures the distance to the rock surface with a laser device that measures distance with an accuracy of 0.001 in. The rock sample is mounted on a servo-table that automatically moves the sample in selectable increments (typically, 0.025 in.). With this device, the surface of a standard API fracture-conductivity sample can be scanned in a few hours, and a digitized profile image can be obtained. This digital image is used to characterize the etched surface topography quantitatively.

We have measured the etched-fracture-surface profile for a wide range of acidizing conditions. The etched-surface characteristics depend strongly on the acidizing conditions, including acid type and strength, velocity in the fracture, leakoff rate, and rock type. Results for typical acid-fracturing fluids and conditions are presented along with recommendations for fluid systems that create the smallest-scale differential etching.
Application of Relative Permeability Modifiers To Control Water Cut Following Hydraulic Fracturing in Western Siberia Oilfields—Russian Case-History Study
Authors: Borodin E. G. , Vakhoureshev P. E. , Stolyarov S. M. , Kalfayan L. J.
Published: August 2008

Because of the geological characteristics and low permeability of Western Siberia hydrocarbon reservoirs, hydraulic fracturing is the most effective method for improving hydrocarbon production. During recent years, the massive fracturing treatments in this area have led to a reduction of well candidates for this type of production-enhancement technique. Currently, the majority of selected wells for fracture stimulation are considered risky because of significant water cut increase after stimulation. The question arises: How to reduce water production while enhancing oil production?

This paper reviews 26 case histories exemplifying the use of relatively permeability modifiers (RPMs) in hydraulic fracturing to enhance oil recovery and control water production. Also, results of laboratory studies are included to support the RPM-fracturing concept and -placement techniques.
A Field Study in Optimizing Completion Strategies for Fracture Initiation in Barnett Shale Horizontal Wells
Authors: Ketter A. A. , Heinze J. R. , Daniels J. L. , Waters G.
Published: August 2008

The Barnett shale is an unconventional gas reservoir that currently extends over an estimated 54,000 sq miles. In an effort to improve well economics and to reduce the number of surface locations in populated areas, the number of wells being drilled and completed has rapidly increased. With this change in development strategy, operators and service companies alike have had to search for innovative solutions to overcome challenges faced in horizontal completions.

Inefficient fracture initiation is the largest reoccurring problem encountered when completing horizontal Barnett shale wells. These difficulties have manifested themselves as high-fracture initiation and propagation pressures, which lead to low injection rates and high treating pressures. These losses reduce the efficiency of proppant placement and stimulation. As drilling activity has increased over the past couple of years, fracture-initiation problems are now a substantial source of expense and downtime.

This field study examines 256 horizontal Barnett shale wells in an effort to identify the causes of these near-wellbore issues and to offer corrective solutions for future completions. The goal of this study is to recommend an optimized completion strategy to minimize these near-wellbore problems, increase stimulation coverage, and decrease unplanned completion expenses.

In 2005, 19% of the stages in horizontal wells examined encountered near-wellbore difficulties. This field study inspects the major contributors to fracture initiation, specifically focusing on cccemented vs. uncemented laterals, horizontal-stress anisotropy, perforation strategy, cementing strategy, and stimulation design.

The paper offers statistics on which changes have had the greatest effect on stimulation placement. These problems can cost operators an additional 25% per stage or more. Using these optimized strategies has reduced by 74% the number of stages in which fracture-initiation difficulties have been encountered.
Reaction of Gelled Acids With Calcite
Authors: Nasr-El-Din H. A. , Al-Mohammed A. M. , Al-Aamri A. D. , Al-Fuwaires O.
Published: August 2008

Hydrochloric (HCl) acid is used to stimulate carbonate formations in both matrix and fracturing treatments. However, the reaction rate of the acid with calcite is fast. In addition, the viscosity of regular HCl solutions is relatively low. Acid-soluble polymers are usually added to the acid to increase its viscosity, which is needed to enhance acid diversion during matrix acidizing and reduce acid leakoff rate during acid fracturing. Gelled acids are extensively used in matrix and acid-fracturing treatments performed in carbonate formations. However, a few studies examined the impact of these polymers on the reaction of HCl acids with calcite.

This paper used a rotating disk instrument to measure the dissolution rate of calcite by use of gelled acids. Measurements were conducted over a temperature range of 25 to 65°C, a pressure of 1,000 psi, and rotational speeds of 100 to 1,000 rpm. Acid formulations that are typically used in the field were examined. Polymer concentration was varied from 0.5 to 2 wt%. The apparent viscosity of the gelled acid was measured with a Brookfield viscometer. Measurements were done for the same solutions tested with the rotating disk instrument. The temperature was varied from 25 to 100°C, while the pressure was maintained at 300 psi. The shear rate was varied from 57 to 1,700 s−1.

Evidence of reverse and toroidal flows was noted for the first time by examining the etching patterns of the reacted disks. The etching pattern on the surface of the disk depended, among other factors, on the disk rotational speed and polymer concentration.

There was a significant increase in the apparent viscosity of gelled acids and a major decrease in the dissolution rate as the polymer concentration was increased from 0.5 to 1.5 wt%. The reaction of gelled acids with calcite was controlled by a surface reaction at 25°C, and by mass transfer at 65°C. Temperature increased the dissolution rate of calcite at all conditions examined. It did also reduce the viscosity of the gelled acid, which affected the way the acid reacted with calcite.
Squeeze Chemical for HT Applications—Have We Discarded Promising Products by Performing Unrepresentative Thermal-Aging Tests?
Authors: Wat Rex , Hauge Lars-Even , Solbakken Kåre , Wennberg Kjell Erik , Sivertsen Linda Merete , Gjersvold Berit
Published: August 2008

Selecting an effective scale inhibitor for squeeze application at 170°C is not a simple task. The traditional thermal-stability test of aging the chemical in bulk is often perceived to be too harsh. This results in many promising products being rejected because of their apparent degradation at temperature. The alternative of conducting the aging test inside core materials, which is more representative of the downhole conditions, is not a novel idea. However, to date, no definitive data are available to substantiate such a process and quantify the difference between the two methods. This is mainly because of the difficulties and complexity in conducting such an experiment at a high temperature over a long period of time. In this paper, the results from a recent investigation are presented. We describe the detailed procedures of the planning and execution stages, lessons learned, and pitfalls that must be avoided. A scale inhibitor was aged with two different methods: one in bulk, as commonly practiced in the industry, and one inside a sandstone core. The aging period varied between 45 days for the bulk and 110 days for the last desorbed sample from the core. The samples that were aged inside the core retained much of their inhibition efficiency, while those aged by the traditional method (bulk) lost nearly all their effectiveness. These results demonstrate clearly that the conventional method of thermal aging in bulk is unrepresentative and that the loss in performance can be quantified. A novel finding from this study is the evidence of an unexpected relationship between desorption and inhibition effectiveness. The findings from this study could have great impact on selecting chemicals for high-temperature (HT) applications, even more so in those environmentally sensitive regions where the use of "yellow" (biodegradable) squeeze chemicals is mandatory. Many of these chemicals have been rejected because of their apparent thermal degradation, which has now proved to be unrepresentative.
Production Optimization by Use of the Capillary Technology in the Loma La Lata Field
Authors: Cabral P. , Giérega C. R. , Costanza P. , Suriano A. A.
Published: August 2008

Ever since its discovery in 1977, the Loma La Lata field, located in the Neuquén basin, has been considered one of the most important gas fields in South America.

During the last decade, the progressive reduction in the reservoir pressure has led to successive changes in the field's operation conditions: from high to medium pressure, and, most recently, to low pressure.

As the reservoir pressure depletes, the subsequent reductions in the gas velocities bring about changes in the flow regimes and increasing liquid flow rates. These liquids produced at the wellbore and/or generated by vapor condensation through the production string contribute to increase the pressure drop along the tubing as well as the flowing bottomhole pressure, and will eventually reduce or prevent production.

In most cases, not only does liquid loading arise as a consequence of these changes in operation conditions, but also other production problems, such as mineral scales and organic deposits, and the difficulty to implement corrosion prevention conventional batch treatment programs aimed at extending the life of the production strings.

In addition to these factors, the increasing hydrocarbon demand, Argentina's energy policy, and economic restrictions are also matters of relevance when it comes to implementing conventional solutions that imply several shutdown hours per treated well.

The aforementioned problems have encouraged the operating and services companies to search for technological alternatives providing not only technical solutions but also economical benefits.

After 1 year since a novel capillary string system that allows for the injection of chemical products, and/or the deployment of special devices such as memory gauges at the desired depth was introduced in the country, the results obtained in several tests show a very promising future.

This paper summarizes the first-year results achieved using the capillary string technology as a tool for production enhancement and optimization in the Loma La Lata field.
Lifting Liquids From Natural Gas Wells by Aggressive Formation of Small Droplets
Authors: Christiansen Richard L.
Published: August 2008

When initially completed, many natural gas wells are capable of lifting liquids to the surface. But, with depletion of the reservoir pressure, there comes a time when liquids can no longer be lifted to the surface and they begin to accumulate in the bottom of the well, dramatically inhibiting or stopping gas production. The cause of diminished liquid-lifting ability is the decline of liquid droplet production as gas flow rates pass below the Turner-Hubbard-Dukler critical velocity. In this research, a variety of devices were tested for enhancing droplet production and liquid lifting at low gas flow rates. The devices included vibrational, rotational, and two-fluid means for droplet production. Tests in a flow loop showed that the vibrational devices are most promising for commercial application. A correlation for droplet size as a function of frequency was extended for application at any frequency of interest. Tests with a flow loop show that 3 micron drops can be transported easily at low flow rates. Heuristics in the literature on droplet transport lead to the expectation that droplets with diameters less than 30 microns can be transported from the bottom of a well to the surface without significant difficulty. An energy analysis shows that a barrel of water can be converted to 30-micron droplets for 3 to 30 cents.
Extracting Forward-Looking Information from Security Prices: A New Approach
Authors: Weiss Dan , Naik Prasad A. , Tsai Chih-Ling
Published: August 2008

ABSTRACT: This paper proposes a new index to extract forward-looking information from security prices and infer market participants’ expectations of future earnings. The index, called market-adapted earnings (MAE), utilizes stock returns and fundamental accounting signals to estimate market expectations of future earnings at the firm level. MAE outperforms time-series models (e.g., random-walk) in predicting future earnings. Results demonstrate the usefulness of MAE for firms that have no analyst following.
The Effects of Perceived Fairness and Communication on Honesty and Collusion in a Multi-Agent Setting
Authors: Zhang Yue
Published: August 2008

ABSTRACT: This study examines how two factors, the agents’ perceptions regarding the fairness of the principal and inter-agent communication, affect agents’ behaviors under a peer reporting system. Analytical models show that when agents can observe each other’s actions and local signals, a peer reporting system with a verification mechanism (using one agent’s information to verify the other’s) and a reward for truthful whistleblowing can induce agents to report honestly and thereby help the principal achieve the first-best outcome. However, behavioral research suggests that the agents’ perception regarding the fairness of the principal, as well as communication among agents, may affect how honestly agents report. The results of my experiment show that, under a peer reporting system with a high reward for whistleblowing, the agents’ perception regarding the fairness of the principal positively affects the agents’ reporting honesty and negatively affects their explicit attempts at collusion. Communication between agents decreases their reporting honesty when the principal is perceived as unfair, but not when the principal is perceived as fair.
Morphology and Etiology Meet at the Maternal-Fetal Interface
Authors: Katzman Philip J.
Published: August 2008

Molecular diagnostic testing is leaving its mark in many areas of medicine; no less in perinatal pathology. This CONTEXT article uses the finding of Gogia and Machin in this issue of Pediatric and Developmental Pathology that genetic or acquired thrombophilias are associated with fetal thrombotic vasculopathy, massive perivillous fibrin deposition, and maternal floor infarction as an example of how molecular testing is providing possible etiologies for entities that heretofore have largely been only morphologic diagnoses.
Spectral confocal reflection microscopy using a white light source
Authors: Booth Martin J. , Juškaitis Rimas , Wilson Tony
Published: August 2008

We present a reflection confocal microscope incorporating a white light supercontinuum source and spectral detection. The microscope provides images resolved spatially in three-dimensions, in addition to spectral resolution covering the wavelength range 450-650 nm. Images and reflection spectra of artificial and natural specimens are presented, showing features that are not normally revealed in conventional microscopes or confocal microscopes using discrete-line lasers. The specimens include thin film structures on semiconductor chips, iridescent structures in Papilio blumei butterfly scales, nacre from abalone shells and opal gemstones. Quantitative size and refractive index measurements of transparent beads are derived from spectral interference bands.
Lifestyle incongruity, stress and immune function in indigenous Siberians: The health impacts of rapid social and economic change
Authors: Sorensen Mark V. , Snodgrass James J. , Leonard William R. , McDade Thomas W. , Tarskaya Larissa A. , Ivanov Kiundiul I. , Krivoshapkin Vadim G. , Alekseev Vladimir P.
Published: August 2008

The purpose of this study was to investigate the impact of economic and cultural change on immune function and psychosocial stress in an indigenous Siberian population. We examined Epstein‐Barr virus antibodies (EBV), an indirect biomarker of cell‐mediated immune function, in venous whole blood samples collected from 143 Yakut (Sakha) herders (45 men and 98 women) in six communities using a cross‐sectional study design. We modeled economic change through the analysis of lifestyle incongruity (LI), calculated as the disparity between socioeconomic status and material lifestyle, computed with two orthogonal scales: market and subsistence lifestyle. EBV antibody level was significantly negatively associated with both a market and a subsistence lifestyle, indicating higher cell‐mediated immune function associated with higher material lifestyle scores. In contrast, LI was significantly positively associated with EBV antibodies indicating lower immune function, and suggesting higher psychosocial stress, among individuals with economic status in excess of material lifestyle. Individuals with lower incongruity scores (i.e., economic status at parity with material resources, or with material resources in excess of economic status) had significantly lower EBV antibodies. The findings suggest significant health impacts of changes in material well‐being and shifting status and prestige markers on health during the transition to a market economy in Siberia. The findings also suggest that relative, as opposed to absolute, level of economic status or material wealth is more strongly related to stress in the Siberian context. Am J Phys Anthropol, 2009. © 2008 Wiley‐Liss, Inc.
Behavioral adaptations to heat stress and water scarcity in white‐faced capuchins (Cebus capucinus) in Santa Rosa National Park, Costa Rica
Authors: Campos Fernando A. , Fedigan Linda M.
Published: August 2008

We examined thermoregulatory behaviors in a wild population of white‐faced capuchins (Cebus capucinus) inhabiting a highly seasonal dry forest in Santa Rosa National Park (SRNP), Costa Rica. The dry season in SRNP lasts ∼5 months and is characterized by high ambient temperatures regularly exceeding 37°C, low relative humidity, and the near absence of precipitation. This study demonstrates that capuchins rest more and travel shorter distances during the hottest and driest hours of the day, and suggests that they extend their tongues to lower body temperature via evaporative cooling. Seasonal weather patterns and group movement data reported here are based on 940 h of observations on three social groups of capuchins (wet season: 370 h, dry season: 570 h). In the dry season, the proportion of time spent resting increased at higher temperatures whereas the proportion of time spent traveling decreased. Distance traveled between location points taken at half‐hour intervals decreased significantly as temperature increased, although the correlation was not strong. Capuchins exposed their tongues during hot, dry, windy conditions, and this behavior was much more frequent in the dry season. Temperature was significantly higher and humidity significantly lower for “tongue‐out” events than expected for a random event in the dry season. Finally, as surface water became scarce, home‐range areas of heavy use became increasingly centered on the remaining permanent water sources. These results suggest that heat stress and water scarcity are significant influences on the behavior of capuchins in hot, dry conditions. Am J Phys Anthropol, 2009. © 2008 Wiley‐Liss, Inc.
Surnames in Siberia: A study of the population of Yakutia through isonymy
Authors: Tarskaia L. , El'chinova G.I. , Scapoli C. , Mamolini E. , Carrieri A. , Rodriguez‐Larralde A. , Barrai I.
Published: August 2008

We studied the isonymic structure of the Republic of Sakha (Yakutia), in the Russian Federation, using the surname distributions of 491,259 citizens above 18 years registered as residents in 2002. These were distributed in 35 districts and 497 towns and settlements of the Republic. The number of different surnames was 44,625. Matrices of isonymic distances between the 35 districts were tested for correlation with the geographic distance between the population centers of gravity of thedistricts. We found that, for the whole of Yakutia, Nei's distance was correlated with geographic distance (r = 0.693 ± 0.027). A dendrogram of the 35 districts was built from the distance matrix, using the UPGMA method. The clusters identified by the dendrogram correlate with the geographic position of the districts. The correlation of random inbreeding calculated from isonymy, FST, with latitude was positive and highly significant but weak (r = 0.23). So, inbreeding was highest in the Arctic districts, and lowest in the South. Average α for 497 towns was 107, for 35 districts it was 311, and for the Republic 433. The value of α was higher for Russian than for the local languages. The geographical distribution of α, high in the Center and South‐East and lower in the North‐West, is compatible with the settlement of groups of migrants moving from the South‐East toward the center and the North of Yakutia. It is proposed that low‐density demic diffusion of human populations results in high inbreeding and may have been a general phenomenon in the early phases of human radiations. Am J Phys Anthropol 2009. © 2008 Wiley‐Liss, Inc.
Adsorption for metal ions of chitosan coated cotton fiber
Authors: Zhang Guoyuan , Qu Rongjun , Sun Changmei , Ji Chunuan , Chen Hou , Wang Chunhua , Niu Yuzhong
Published: August 2008

A kind of adsorbent for metal ions, cotton fiber coated by high loading of chitosan (SCCH) was prepared. Its structure was characterized by elemental analysis, scanning electronic microscopy (SEM), Fourier transform infrared spectrum (FTIR), and wide‐angle X‐ray diffraction (WAXD). The adsorption properties of SCCH for Cu2+, Ni2+, Pb2+, Cd2+, such as saturated adsorption capacities, static kinetics, and isotherm were investigated. The adsorption for Ni2+, Pb2+, and Cd2+ was controlled by liquid film diffusion, but by particle diffusion for Cu2+. The adsorption process for Cu2+, Ni2+, Cd2+ could be described with Langmuir or Freundlich equation, but only with Freundlich equation for Pb2+. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Properties of a poly(L‐lactic acid)/poly(D‐lactic acid) stereocomplex and the stereocomplex crosslinked with triallyl isocyanurate by irradiation
Authors: Quynh Tran Minh , Mitomo Hiroshi , Zhao Long , Tamada Masao
Published: August 2008

A poly(L‐lactic acid) (PLLA)/poly(D‐lactic acid) (PDLA) stereocomplex was prepared from an equimolar mixture of commercial‐grade PLLA and PDLA by melt processing for the first time. Crosslinked samples were obtained by the radiation‐induced crosslinking of the poly(lactic acid) (PLA) stereocomplex mixed with triallyl isocyanurate (TAIC). The PLA stereocomplex and its crosslinked samples were characterized by their gel behavior, thermal and mechanical measurements, and enzymatic degradation. The crosslinking density of the crosslinked stereocomplex was described as the gel fraction, which increased with the TAIC content and radiation dose. The maximum crosslinking density was obtained in crosslinked samples of PLA/3% TAIC and PLA/5% TAIC irradiated at doses higher than 30 kGy. The stable crosslinking networks that formed in the irradiated PLA/TAIC substantially suppressed the segmental mobility for the crystallization of single crystals as well as stereocomplex crystals. The crosslinking network also significantly improved the mechanical properties and inhibited the enzymatic degradation of crosslinked PLA/3% TAIC. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
In situ encapsulation of tetradecane droplets in oil‐in‐water emulsions using amino resins
Authors: Sgraja Martin , Blömer Jan , Bertling Jürgen , Jansens Peter J.
Published: August 2008

Microcapsules of tetradecane enclosed by a polymeric wall of amino resin were synthesized by the in situ polymerization using melamine‐formaldehyde precondensates. It was found that resin concentrations of 60–240 g L‐1 for a phase volume fraction of 0.14 and 0.29 and concentrations of 50–240 g L‐1 for a phase volume fraction of 0.43 lead to stable microcapsules. Furthermore, the dependence of the shell thickness from the resin concentration for a phase volume fraction of 0.29 was investigated whereas the shell thickness was calculated from the density and the mean diameter of the capsules. It was found that below a concentration of 100 g L−1 the density and thus the shell thickness increases linear with the resin concentration whereas at higher concentrations it almost remains constant and only the amount of the resin precipitated in solution increases. Additionally, it was shown that the mean droplet size (which is almost equal to the capsule size) in dependence of the stirring speed can be derived from the theory of droplet disruption. Thereby the coherence beginning with the stirring speed and the mean diameter to the total surface and the shell thickness is described. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Preparation of Carmustine‐loaded PLA ultrasmall‐nanoparticles by adjusting micellar behavior of surfactants
Authors: Yan Cheng‐hu , Yuan Xu‐bo , Kang Chunsheng , Zhao Yun‐Hei , Liu Jie , Guo Yanshuang , Lu Jian , Pu Peiyu , Sheng Jing
Published: August 2008

Carmustine‐loaded poly(lactic acid) (PLA) nanoparticles were prepared with a spontaneous emulsification‐solvent diffusion method by using Pluroinc F68 as emulsifying agent, and the influence of micellar behavior of surfactant in aqueous solution on the sizes of the nanoparticles was studied. The results revealed that F68 dissolved as unimers in water or sodium acetate‐acetic acid buffer with pH value ranged from 5.0 to 5.5, resulting in larger PLA particles (226 nm) or clumps. In acidic media with pH of 4.0 and 4.5, however, F68 aggregated into micelles over the concentration of 3.7 and 4.8 mg/mL, as a result, ultrasmall nanoparticles with a size 50 and 80 nm could be obtained, respectively. The change in size had less effect on the drug content and entrapment efficiency, and the nanoparticles strongly enhanced the cytotoxic effect of the loaded drug in vitro, and this effect being more relevant for prolonged incubation times. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Stability studies on blends of a lactic acid‐based hot melt adhesive and starch
Authors: Inkinen Saara , Stolt Mikael , Södergård Anders
Published: August 2008

The stability of 70 : 24 : 6 w/w/w blends of a lactic acid‐based hot melt adhesive (LHM), oxidized potato starch (dried or nondried), and polyethylene glycol (PEG) was studied. Pure LHM was used as a reference material. The methods used included tensile testing, water absorption, and scanning electron microscopy (SEM). During the ageing period of 56 days at ambient conditions (23± 1°C and 42 ± 4% RH), the tensile properties of the blends were close to each other, and all of the studied materials had relatively low Young's moduli, compared to reported PLA‐starch blends. In the water absorption experiment (23 ± 1°C), the blends reached significantly higher maximum values than the LHM. The blends also started to disintegrate already after 3 days in water, while the water absorption of pure LHM could be studied for 49 days without detectable disintegration. The SEM images showed that the tensile testing fractures occurred via the continuous LHM matrix in the blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Encapsulation efficiency and release behaviors of bovine serum albumin loaded in alginate microspheres prepared by spraying
Authors: Zhang Jie , Li Xiaohui , Zhang Daijia , Xiu Zhilong
Published: August 2008

Spraying and spraying with an electrostatic field (SEF) were employed to prepare alginate microspheres for delivering proteins, especially for intestinal digestive enzymes and cytokines. The encapsulation efficiency (EE) of a model protein [bovine serum albumin (BSA)] at a pH value lower than the isoelectric point was 20% higher than that at a natural pH. Moreover, for the microspheres prepared by SEF, EE improved significantly with increasing electric voltage. The interactions between BSA and the alginate microspheres were identified with Fourier transform infrared spectroscopy. The release profiles in vitro showed a controlled and pH‐responsive release manner for the encapsulated BSA. A first‐order release equation was postulated and modified to describe the release kinetics with an obviously initial burst release related to the eroded porous matrix. The equation fit the release data well when the pH value and composition of the release media were changed. The analysis of the release kinetics indicated that the drug release rate was in an inverse ratio to the diameter of the microspheres. Increasing the gas flow rate or electric voltage decreased both the mean diameter and size distribution of the microspheres significantly and enhanced the release rate of loaded drugs from alginate microspheres. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis analysis revealed that BSA kept its structural integrity during the encapsulation and release process. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008