bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of the post‐translational modification of recombinant human BMP‐15 mature protein
Authors: Saito Seiji , Yano Keiichi , Sharma Shweta , McMahon Heather E. , Shimasaki Shunichi 
Published: January 2008

AbstractBone morphogenetic protein‐15 (BMP‐15) is an oocyte‐secreted factor critical for the regulation of ovarian physiology. When recombinant human BMP‐15 (rhBMP‐15) produced in human embryonic kidney 293 cells was subjected to SDS‐PAGE analysis, two mature protein forms corresponding to 16 kDa (P16) and 17 kDa (P17) were observed. Despite the physiological relevance and critical function of BMP‐15 in female reproduction, little is known about the structure of rhBMP‐15. Here, we have analyzed the structure of the rhBMP‐15 mature proteins (P16 and P17) using state‐of‐the‐art proteomics technology. Our findings are as follows: (1) the N‐terminal amino acid of P16 and P17 is pyroglutamic acid; (2) the Ser residue at the sixth position of P16 is phosphorylated; (3) P17 is O‐glycosylated at Thr10; and (4) the C‐terminal amino acid of P16 and P17 is truncated. These findings are the first knowledge of the structure of rhBMP‐15 mature protein toward understanding the molecular basis of BMP‐15 function and could provide an important contribution to the rapidly progressing research area involving oocyte‐specific growth factors in modulation of female fertility.
Solution NMR structure of the N‐terminal domain of the human DEK protein
Authors: Devany Matthew , Kappes Ferdinand , Chen Kuan‐Ming , Markovitz David M. , Matsuo Hiroshi 
Published: January 2008

AbstractThe human DEK protein has a long‐standing association with carcinogenesis since the DEK gene was originally identified in the t(6:9) chromosomal translocation in a subtype of patients with acute myelogenous leukemia (AML). Recent studies have partly unveiled DEK's cellular functions including apoptosis inhibition in primary cells as well as cancer cells, determination of 3′ splice site of transcribed RNA, and suppression of transcription initiation by polymerase II. It has been previously shown that the N‐terminal region of DEK, spanning residues 68–226, confers important in vitro and in vivo functions of DEK, which include double‐stranded DNA (ds‐DNA) binding, introduction of constrained positive supercoils into closed dsDNA, and apoptosis inhibition. In this paper, we describe the three‐dimensional structure of the N‐terminal domain of DEK (DEKntd) as determined using solution NMR. The C‐terminal part of DEKntd, which contains a putative DNA‐binding motif (SAF/SAP motif), folds into a helix‐loop‐helix structure. Interestingly, the N‐terminal part of DEKntd shows a very similar structure to the C‐terminal part, although the N‐terminal and the C‐terminal part differ distinctively in their amino acid sequences. As a consequence, the structure of DEKntd has a pseudo twofold plane symmetry. In addition, we tested dsDNA binding of DEKntd by monitoring changes of NMR chemical shifts upon addition of dsDNAs. We found that not only the C‐terminal part containing the SAF/SAP motif but the N‐terminal part is also involved in DEKntd's dsDNA binding. Our study illustrates a new structural variant and reveals novel dsDNA‐binding properties for proteins containing the SAP/SAF motif.
Effects of Couple Stress on Elastohydrodynamic Lubrication at Impact
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Authors: Chu Hsiao-Ming , Li Wang-Long , Chang Yuh-Ping , Huang Huan-Chang 
Published: January 2008

Abstract
In this paper, pure squeeze elastohydrodynamic lubrication motion of circular contacts with couple stress lubricant is explored at impact loading. On the basis of microcontinuum theory, the transient modified Reynolds equation is derived. Then it is solved simultaneously with the elasticity deformation equation and ball motion equation, thus obtaining the transient pressure profiles, film shapes, normal squeeze velocities, and accelerations. The simulation results reveal that the effect of the couple stress is equivalent to enhancing the lubricant viscosity, which would also enlarge the damper effect. Therefore, as the characteristic length of the couple stress fluid increases, the pressure spike and the dimple form earlier, the maximum pressure and the film thickness increase, and the diameter of the dimple, the rebounding velocity, the maximum value of the relative impact force, and the acceleration decrease. Furthermore, the fact that the contact central pressure for a ball impacting and rebounding from a lubricated surface reached two peaks during the total impact period is proved numerically in this analysis. As the effect of couple stress increases, the first and second peaks form earlier; as the total impact time decreases, the pressure of the first peak increases and that of the second peak decreases. Moreover, the phase shift between the time of the peak value of the squeeze acceleration and the zero value of the squeeze velocity increases with increasing the characteristic length of the couple stress fluid.
Iron oxides in tropical soils on various parent materials
Authors: Wiriyakitnateekul W. , Suddhiprakarn A. , Kheoruenromne I. , Smirk M. N. , Gilkes R. J. 
Published: January 2008

AbstractTwenty nine Fe oxide concentrates of Thai soils formed on basalt, sandstone, shale/limestone and granite were investigated. Goethite and hematite are relatively more abundant in granitic and basaltic soils, respectively. Values of Feo/Fedrange from 0.01 to 0.28 indicating that free Fe oxides are mostly crystalline.There are no systematic differences in unit-cell dimensions for goethite and hematite in soils on different parent materials. Mean crystallite dimensions calculated from the 110 reflections are greater for hematite than for goethite. Aluminium substitution varies from 8 to 24 mole% for goethite and from 4 to 17 mole% for hematite. The dehydroxylation temperature for goethite ranges from 285ºC to 320ºC. The goethite in basaltic soils has a smaller crystal size and Al substitution, as well as a lower dehydroxylation temperature, compared to soils on other parent materials. The dehydroxylation temperature of goethite is positively related to Al substitution (R= +0.58), MCD110 (R= +0.49) and Ald (R= +0.53). The Mn, Ni, Cr, V and P in these soils occur in Fe oxides rather than as discrete minerals.
Crystallochemistry of Fe-rich palygorskite from eastern China
Authors: Li Z. , He K. , Yin L. , Xiong F. , Zheng Y. C. 
Published: January 2008

AbstractIron cations in the octahedral sheet are a disadvantage to the industrial application of palygorskite clays. In this study, a palygorskite sample from eastern China (Mayaoshan deposit, Jiangsu Province) is shown to have an Fe content that is much greater than usual. The structural formula of the Fe-rich palygorskite sample was established as (Si7.48Al0.52) (Al1.24Fe0.94Mg1.77Ti0.03⁏1.02)O20(OH)2(OH2)4. The palygorskite is seen to be dioctahedral according to the structural formula, consistent with Fourier transform infrared data. Occurrences of AlFe3+ɏOH and Fe3+Fe3+ɏOH vibrations in the OH-stretching and -bending regions show that Fe atoms occupy inner sites of octahedral sheets. A Mössbauer spectrum confirmed that Fe ions occupy inner octahedral sites as trivalent Fe cations (Fe3+).
Characterization of products obtained by acid leaching of Fe-bentonite
Authors: Madejová J. , Andrejkovičová S. , Bujdák J. , Čeklovský A. , Hrachová J. , Valúchová J. , Komadel P. 
Published: January 2008

AbstractThis study focused on the structure and physical properties of acid-treated bentonite L45 from the Lieskovec deposit (Slovakia). New applications of near infrared and visible spectroscopies were used to follow Fe-montmorillonite dissolution and layer-charge reduction. Progressive dissolution of L45 results in the formation of a protonated amorphous silica phase. The OH overtone at 7312 cm–1 revealed the creation of Si–OH groups in the mildly treated samples. The area of the Si–O–Moct band, as obtained by a peak-fitting procedure, is a sensitive indicator of the changes in the octahedral sheets. Ultraviolet-visible (UV-VIS) spectroscopy of the smectite dispersions with methylene blue (MB) is an efficient method for controlling the acid activation process of bentonites. The results reveal that acid treatment causes a substantial layer-charge reduction, probably due to prevailing dissolution of MgO4(OH)2 polyhedra in the octahedral sheets. The layer-charge reduction is proportional to the structural changes and to the extent of mineral decomposition upon acid treatment.
Surface modification of bentonites. VI. Sol-gel transitions of sodium and calcium montmorillonite dispersions in the presence of anionic end-capped poly(ethylene oxides)
Authors: Ziesmer S. , Lagaly G. 
Published: January 2008

AbstractPoly(ethylene oxides) (PEOs) with sulphonate groups attached at both chain ends (S-PEOs) were strongly adsorbed by dispersed Na- and Ca-montmorillonite particles. The amounts adsorbed were very similar to those of cationic end-capped poly(ethylene oxides). In both cases bilayers of PEO chains were intercalated so that the basal spacing of the particles reached the same plateau values of ~1.73 nm. In contrast, the influence of anionic PEOs on the colloidal behaviour of the Na- and Ca-montmorillonite dispersions was very different from the effect of the cationic PEOs. The shorter chain S-PEOs (S-PEO 1500, 4000) destabilized the Na-montmorillonite dispersions by coagulation due to the Na+ ions introduced as counterions to the S-PEOs. The longer chain S-PEO 20000 and S-PEO 35000 did not coagulate the Na-montmorillonite sols because the corresponding Na+ concentration did not reach the critical coagulation value. The slightly enhanced salt tolerance indicated that the long-chain PEOs exerted a weak steric stabilization. In contrast, bridging of the particles by S-PEO molecules and Ca2+ ions played an important role in destabilizing the Ca-montmorillonite dispersions in the form of flocs and formation of gels.
The NF-κB subunit Rel A is associated with in vitro survival and clinical disease progression in chronic lymphocytic leukemia and represents a promising therapeutic target
Authors: Hewamana Saman , Alghazal Suhair , Lin Thet Thet , Clement Matthew , Jenkins Chris , Guzman Monica L. , Jordan Craig T. , Neelakantan Sundar , Crooks Peter A. , Burnett Alan K. , Pratt Guy , Fegan Chris , Rowntree Clare , Brennan Paul , Pepper Chris 
Published: January 2008

Abstract
In this study, we characterized nuclear factor κB (NF-κB) subunit DNA binding in chronic lymphocytic leukemia (CLL) samples and demonstrated heterogeneity in basal and inducible NF-κB. However, all cases showed higher basal NF-κB than normal B cells. Subunit analysis revealed DNA binding of p50, Rel A, and c-Rel in primary CLL cells, and Rel A DNA binding was associated with in vitro survival (P = .01) with high white cell count (P = .01) and shorter lymphocyte doubling time (P = .01). NF-κB induction after in vitro stimulation with anti-IgM was associated with increased in vitro survival (P < .001) and expression of the signaling molecule ZAP-70 (P = .003). Prompted by these data, we evaluated the novel parthenolide analog, LC-1, in 54 CLL patient samples. LC-1 induced apoptosis in all the samples tested with a mean LD50 of 2.8 μM after 24 hours; normal B and T cells were significantly more resistant to its apoptotic effects (P < .001). Apoptosis was preceded by a marked loss of NF-κB DNA binding and sensitivity to LC-1 correlated with basal Rel A DNA binding (P = .03, r2 = 0.15). Furthermore, Rel A DNA binding was inversely correlated with sensitivity to fludarabine (P = .001, r2 = 0.3), implicating Rel A in fludarabine resistance. Taken together, these data indicate that Rel A represents an excellent therapeutic target for this incurable disease.
Effects of a Waiting Period After Clopidogrel Treatment Before Performing Coronary Artery Bypass Grafting
Authors: Reichert Marc G. , Robinson Amanda H. , Travis Jeffrey A. , Hammon John W. , Kon Neal D. , Kincaid Edward H. 
Published: January 2008

Study Objective. To assess the effects of a waiting period after clopidogrel treatment before coronary artery bypass grafting (CABG).Design. Single‐center, prospective, observational study.Setting. Cardiothoracic surgery intensive care unit at a university‐affiliated medical center.Patients. One hundred consecutive patients who received clopidogrel and were scheduled to undergo primary CABG. In 64 of these patients, CABG was delayed at least 5 days after clopidogrel treatment (group A). The other 36 patients received clopidogrel treatment within 5 days of undergoing CABG (group B).Measurements and Main Results. Data were collected on patient demographics, time of last clopidogrel dose, preoperative anticoagulant and/or antiplatelet agents administered, surgical characteristics, intraoperative transfusions, blood products transfused, and chest tube output for 24 hours after surgery. No significant differences in baseline characteristics or intraoperative variables (number of bypasses, aortic cross‐clamp time, and cardiopulmonary bypass time) were noted between the two groups. Mean ± SD number of packed red blood cell units/patient was 1.1 ± 1.4 in group A versus 2.1 ± 2.5 in group B (p=0.009). Mean ± SD number of platelet units/patient transfused was 0.5 ± 0.9 in group A versus 1.9 ± 1.6 in group B (p <0.001). When comparing a subset of 21 patients who received clopidogrel within 72 hours of surgery with the 64 whose CABG was delayed at least 5 days after clopidogrel treatment, the transfusion rates were significantly higher (95% vs 52%, p<0.05). Specifically, the mean ± SD number of transfused units/patient of red blood cells (3.1 ± 2.8 vs 1.1 ± 1.4, p<0.005) and platelets (2.6 ± 1.5 vs 0.5 ± 0.9, p<0.007) was greater in patients who received clopidogrel within 72 hours of surgery.Conclusion. A strategy to delay CABG after clopidogrel treatment led to reduced blood product administration. The optimal waiting period after clopidogrel treatment is not known but appears to be at least 5 days before CABG.
Managed Pressure Drilling Resolves Pressure Depletion Related Problems in the Development of the HPHT Kristin Field
Authors: Solvang S. A. , Leuchtenberg C. , Gil I. C. , Pinkstone H. 
Published: January 2008

Abstract
Depletion of the Kristin HPHT field (911 bar, 172° C / 13,213 psi, 342° F) is occurring, challenging the drilling of future increased recovery wells. The main concern is uncertainty of the reservoir pressures in development areas of the producing intervals. Initially, the operational window range for the bottomhole pressure (BHP) varied from a pore pressure of 1.97 SG to a fracture pressure of 2.14-2.16 SG. With depletion, the difference has become narrower since fracture pressure is decreasing.
This paper describes the need to implement managed pressure drilling (MPD) techniques in the Kristin field to overcome the problems related to a narrow drilling window. MPD is a technique that allows the use of lower-density drilling fluid, minimizing the overbalance pressure. Thus, BHP can be easily controlled and changed by applying surface-back pressure using a closed and pressurized circulation system and an automated choke. Circulating and static BHP can be increased rapidly, by applying back pressure at surface, if a higher than expected reservoir pressure is encountered. Conversely, BHP can rapidly be reduced, by reducing surface back pressure, should losses be seen down hole.
The paper will discuss the use of a drilling fluid with a density giving a hydrostatic pressure lower than the original pore pressure to facilitate drilling operations and allow better control of the BHP for drilling future wells in the Kristin Field.
The Kristin development wells may be the first wells globally to use MPD techniques in a harsh weather offshore environment on a floating drilling installation. The paper will also discuss some of the new equipment which has been designed to allow the implementation of MPD techniques in a harsh weather offshore environment from a semi submersible rig.
Successful Use of Underbalanced-Drilling in a Cluster of Fields, North Oman
Authors: Carrera Mariano , Al Hadhrami Hamed , Al Jabri Hamed 
Published: January 2008

Abstract
Under-Balance Drilling (UBD) has been used in several carbonate fields of the Cluster, North Oman at Petroleum Development Oman (PDO). The reasons have been to improve productivity and injectivity, real-time reservoir characterization and to reduce/eliminate acid clean out. By using UBD in several fields, a better picture of well candidate selection and benefits has been derived.
In this paper we will present the results of successful utilization of UBD that may be applied to other fields. The results include an improvement in productivity, real-time decision making and a better understanding of reservoir flow characteristics. In summary the success of UBD depends on the selection of the fields which we elaborate on using several examples. These examples will demonstrate in details the history, application and benefits of UBD. The presentation will also illustrate future work planned using UBD.
Constant Bottomhole Pressure: Managed-Pressure Drilling Technique Applied in an Exploratory Well in Saudi Arabia
Authors: Vieira P. , Arnone M. , Russel B. , Cook I. , Moyse K. , Torres F. , Qutob Hani , Yuesheng Chen , Qing Chen 
Published: January 2008

Abstract
The proposed well is an exploratory well where the formation pressures were estimated based on the experience in drilling offset wells in the area. The 8 3/8" and 5 7/8" hole sections, have a wide range of predicted pore pressure, indicating a considerable span of uncertainty in addition to other related conventional drilling problems as tight hole and gas influx. In previous wells drilled in the area, many drilling problems and wellbore stability issues were experienced. One of the possible cuases of the mechanical instability could be attributed to the large fluctuations in the bottom hole pressure that is intrinsic to conventional drilling practices. These fluctuations are originated from the stopping and starting of drilling fluid circulation during jointed pipe connections, specifically, they result from the fluctuation in the equivalent circulating density (ECD), which occurs when the pumps are turned on and off. This fluctuation could triger a kick-Loss scenario that increases the Non Productive Time (NPT). drilling-related flat time further indicate a necessity for a technology that enables more precise wellbore pressure management.
Constant Bottom Hole Pressure (CBHP) which is variation of MPD, is applicable to avoid changes in ECD by applying appropriate levels of surface backpressure, a technique that maintains constant bottom-hole pressure during the complete drilling operation. The primary objective of drilling this well using the Managed Pressured Drilling technology was to reach the target depth with minimum drilling complication, avoid uncontrolled event by maintaining a constant bottom hole pressure and properly managing the well in case an underbalanced condition occurs while drilling the 8 3/8" and 5 7/8" hole sections.
As with any advanced drilling technique, successful application of MPD technology required a detailed understanding of the potential benefits as well as limitations. This paper summarizes the process that was used to identify, plan, and implement MPD as a technology to drill the well to the target depth and prevent conventional. Planning and operational results are presented in this paper.
Combined Underbalanced/Coiled-Tubing Drilling Technologies Have Improved Oil Recovery and Activated Abandoned Wells in Hassi Messaoud Field, Algeria
Authors: Amor Bachir Ben , Ferhat Ali , Messas Rafik , Arnone Maurizio , Schoch Fritz , Vieira Paco , Chopty James , Qutob Hani 
Published: January 2008

Abstract
The combination of Underbalanced and Coiled Tubing Drilling technologies has proven to be a viable solution to successfully drill horizontal re-entry wells in mature fields where the reservoir pressure is adequate to induce underbalanced conditions using single phase or multiphase drilling fluid injection.
This is the first of its kind Underbalanced-Coiled Tubing Drilling project undertaken in Hassi Messaoud field. The candidate wells are from a pool of vertical abandoned wells drilled in the western area of the field and have seized to produce with varying completion string and production casing. The increase in the number of candidates for thru tubing re-entries in addition to the depletion of the reservoir, have raised the importance of using the combined Underbalanced-Coiled Tubing Drilling technologies in Hassi Messaoud field.
The experience in this field has validated the benefits of the combination of these technologies and has been attributed to the excellent balance between drilling cost and improved productivity. For example, the drilling cost in the short radius re-entry wells drilled with coiled tubing are highly reduced due to the elimination of pipe connection procedures, the increase in rate of penetration, prevention of conventional drilling problems such as fluid circulation loses and related differential sticking events, increase in the bit life and reduction in time and drilled distance to reach the profitable production level.
This paper describes the technical basis for the design of the Underbalanced-Coiled Tubing Drilling project in Hassi Messaoud field-Algeria, and highlights the operational results, key factors and challenges faced during three consecutive successful re-entry wells drilled in this field.
MPD Planning: How Much Is Enough?
Authors: Spriggs Paul , Frink Philip J. 
Published: January 2008

Abstract
The purpose of this paper is to address the key drivers and risks associated with the use of Applied Back Pressure Managed Pressure Drilling. One of the two key issues to understand early on is whether the well can be drilled statically overbalanced or needs to be drilled with a statically underbalanced fluid. The second issue to comprehend is the level of service needed to avoid compromising safety and well objectives. Answering these two questions defines the path to be followed for adequate planning.
Detailed planning aspects, such as flow modeling, crew training, operational procedures, process flow diagrams and HAZID / HAZOPs meetings are also described in this paper. By asking the ‘what if’ questions prior to operations, it should become apparent what additional surface equipment is required to safely and efficiently drill in MPD mode. Control of the ‘what if's should help to keep the planning and rig up both reasonable and cost effective.