bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glacial modification of granite tors in the Cairngorms, Scotland
Authors: Hall A. M. , Phillips W. M. 
Published: August 2006

AbstractA range of evidence indicates that many granite tors in the Cairngorms have been modified by the flow of glacier ice during the Pleistocene. Comparisons with SW England and the use of a space–time transformation across 38 tor groups in the Cairngorms allow a model to be developed for progressive glacial modification. Tors with deeply etched surfaces and no, or limited, block removal imply an absence of significant glacial modification. The removal of superstructure and blocks, locally forming boulder trains, and the progressive reduction of tors to stumps and basal slabs represent the more advanced stages of modification. Recognition of some slabs as tor stumps from which glacial erosion has removed all superstructure allows the original distribution of tors to be reconstructed for large areas of the Cairngorms. Unmodified tors require covers of non‐erosive, cold‐based ice during all of the cold stages of the Middle and Late Pleistocene. Deformation beneath cold‐based glacier ice is capable of the removal of blocks but advanced glacial modification requires former wet‐based glacier ice. The depth of glacial erosion at former tor sites remains limited largely to the partial or total elimination of the upstanding tor form. Cosmogenic nuclide exposure ages (Phillips et al., 2006) together with data from weathering pit depths (Hall and Phillips, 2006), from the surfaces of tors and large erratic blocks require that the glacial entrainment of blocks from tors occurred in Marine Isotope Stages (MIS) 4–2, 6 and, probably, at least one earlier phase. The occurrence of glacially modified tors on or close to, the main summits of the Cairngorms requires full ice cover over the mountains during these Stages. Evidence from the Cairngorms indicates that tor morphology can be regarded as an important indicator of former ice cover in many formerly glaciated areas, particularly where other evidence of ice cover is sparse. Recognition of the glacial modification of tors is important for debates about the former existence of nunataks and refugia. Copyright © 2006 John Wiley & Sons, Ltd.
RNA Interference as a tool to study the function of MAD2 in mouse oocyte meiotic maturation
Authors: Wang Jian‐Ying , Lei Zi‐Li , Nan Chang‐Long , Yin Shen , Liu Jinghe , Hou Yi , Li Yun‐Long , Chen Da‐Yuan , Sun Qing‐Yuan 
Published: August 2006

AbstractSpindle checkpoint proteins control entry into anaphase and chromosome segregation. As a member of spindle checkpoint proteins, MAD2 takes a central role in the regulation of anaphase onset and genome integrity. Here, we used MAD2 siRNA transfection approach to study MAD2 functions during mouse oocyte meiotic maturation in vitro. Real‐time PCR and laser scanning confocal microscopy showed that we successfully downregulated MAD2 transcript and protein expression. We further demonstrated that MAD2 downregulation resulted in a shortened duration of meiosis I and meiotic spindle abnormality, suggesting the function of MAD2 in mouse oocyte meiotic maturation. We also showed that MAD2 interference to some extent decreased GVBD rate, but increased apoptosis in mouse oocytes. In conclusion, our study shows that siRNA transfection is an effective tool to study MAD2 functions, and our results provide further evidence for the role of MAD2 as a spindle checkpoint protein in mouse oocytes. Mol. Reprod. Dev. 74: 116–124, 2007. © 2006 Wiley‐Liss, Inc.
Evidence for blood chimerism in dizygotic spontaneous twin pregnancy discordant for Down syndrome
Authors: Shalev S. A. , Shalev E. , Pras E. , Shneor Y. , Gazit E. , Yaron Y. , Loewenthal R. 
Published: August 2006

AbstractBackgroundA monochorionic‐diamniotic placenta (MCDAP) is rare in dizygotic (DZ) twinning. All reported cases have been documented in pregnancies achieved by the induction of ovulation alone or during the IVF cycle.Methods and ResultsWe report a spontaneous pregnancy in a 39‐year‐old patient with evidence of MCDAP in DZ twins, discordant for trisomy 21. The first and second‐trimester sonographic scans indicated male twins with MCDAP. Amniocentesis, performed because of advanced maternal age, revealed a normal karyotype in one fetus, and trisomy 21 in the other. Molecular studies, performed in order to confirm the zygosity and chorionicity, demonstrated that the fetuses were DZ. In order to identity the affected twin, a detailed sonographic examination was repeated, but no abnormal findings associated with Down syndrome were demonstrated in any of the fetuses. Therefore, umbilical cord blood samples were obtained from both fetuses. Chromosomal analysis revealed in both fetuses two cell lines: a normal cell line of 46,XY and a 47,XY,+ 21 cell line, in 65 and 80% of the cells, respectively. This result was independently confirmed by both FISH and G‐banding. DNA extracted from both cord blood samples demonstrated an admixture of two distinct genotypes in each sample.ConclusionsWe propose that this case represents a monochorionic‐dizygotic twin pregnancy with blood chimerism. The most plausible mechanism underlying this phenomenon is placental fusion early in pregnancy, resulting in an architecturally single placenta originating from two distinct zygotes. The newly formed blood vessels created anastomoses between the DZ twins and allowed reciprocal blood chimerism between the normal and the trisomic twin. Copyright © 2006 John Wiley & Sons, Ltd.
The influence of faith and religion and the role of religious and community leaders in prenatal decisions for sickle cell disorders and thalassaemia major
Authors: Ahmed Shenaz , Atkin Karl , Hewison Jenny , Green Josephine 
Published: August 2006

AbstractObjectivesReligion is believed to have a significant impact on individuals from minority ethnic groups when making decisions about prenatal genetic screening, prenatal diagnosis and termination of pregnancy. This study aimed to explore the views of individuals from South‐Asian and African‐Caribbean communities towards termination of pregnancy for sickle cell disorders and thalassaemia major and the influence of (1) faith and religion, (2) perceived severity of the conditions, and (3) religious and community leaders.MethodsThe study explored the views of (1) individuals from four faith communities (Pakistani Muslims, Indian Hindus, Indian Sikhs, African‐Caribbean Christians), using eight focus groups, and (2) parents of children with sickle cell disorders and thalassaemia major, using two focus groups and three interviews.ResultsParticipants' accounts suggest that they generally considered religion and faith as an important factor in the decision‐making process, but the perceived severity of the condition would play a more important role. Religious and community leaders were believed to have little role to play in the decision‐making process.ConclusionThe findings emphasise the importance of recognising diversity within different faith groups and moving away from stereotypical views based on people's ethnicity or religion, and to consider the beliefs and preferences of individuals. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis and characterization of a helical step‐ladder polyarylene
Authors: Nehls Benjamin S. , Galbrecht Frank , Brauer David J. , Lehmann Christian W. , Scherf Ullrich , Farrell Tony 
Published: August 2006

AbstractA helical step‐ladder polyarylene incorporating chiral (R)‐2,2′‐dioctoxy‐1,1′‐binaphthyl units was synthesized for the first time. The first step involved the preparation of a precursor poly(arylene ketone) via a palladium‐mediated Suzuki‐type cross‐coupling reaction with the aid of microwave heating. Two polymer‐analog reaction steps, the reduction of the keto groups to tertiary alcohol functionalities and subsequent intramolecular Friedel–Crafts cyclization, gave a step‐ladder polymer (6) in good yields with reasonable mean average molecular weights greater than 13,000. The regioselective cyclization pattern in the α position of the naphthalene core was confirmed by a comparison of the NMR data of the polymer with those of the corresponding model ladder oligomers, 12 and 13, and also a single‐crystal structure of 13. The optical spectra of the oligomers and polymers indicated that there was little electronic interaction across the binaphthyl units. The circular dichroism spectrum of 6 exhibited a strong bisignate Cotton effect in the π–π* absorption region of the planar chromophores, which reflected the strong exciton coupling within the helical polymer chain. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5533–5545, 2006
Synthesis and characterization of a novel biodegradable, thermoplastic polyurethane elastomer
Authors: Wang Wenshou , Ping Peng , Yu Haijun , Chen Xuesi , Jing Xiabin 
Published: August 2006

AbstractA series of biodegradable, thermoplastic polyurethane elastomers poly(ϵ‐caprolactone‐co‐lactide(polyurethane [PCLA–PU] were synthesized from a random copolymer of L‐lactide (LA) and ϵ‐caprolactone (CL), hexamethylene diisocyanate, and 1,4‐butanediol. The effects of the LA/CL monomer ratio and hard‐segment content on the thermal and mechanical properties of PCLA–PUs were investigated. Gel permeation chromatography, IR, 13C NMR, and X‐ray diffraction were used to confirm the formation and structure of PCLA–PUs. Through differential scanning calorimetry, tensile testing, and tensile‐recovery testing, their thermal and mechanical properties were characterized. Their glass‐transition temperatures were below −8 °C, and their soft domains became amorphous as the LA content increased. They displayed excellent mechanical properties, such as a tensile strength as high as 38 MPa, a tensile modulus as low as 10 MPa, and an elongation at break of 1300%. Therefore, they could find applications in biomedical fields, such as soft‐tissue engineering and artificial skin. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5505–5512, 2006
Exfoliation of montmorillonite by the insertion of disklike micelles via the soap‐free emulsion polymerization of methyl methacrylate
Authors: Lin King‐Fu , Lin Shanq‐Chyang , Chien An‐Ting , Hsieh Chi‐Chun , Yen Ming‐Huei , Lee Chia‐Hsin , Lin Chao‐Sung , Chiu Wen‐Yen , Lee Yuan‐Hon 
Published: August 2006

AbstractMontmorillonites (MMTs) intercalating a potassium persulfate initiator were readily exfoliated in the presence of polymerizing methyl methacrylate during soap‐free emulsion polymerization. Because of the confined space, the polymerizing chains were aggregated into a disk form inside the clay interlayer regions for micellation. It was surprising to find from X‐ray diffraction analysis that the exfoliation of MMT was almost completed in the micellation stage. Further polymerization afforded latex particles of exfoliated poly(methyl methacrylate) (PMMA)–MMT nanocomposites. In addition, two kinds of MMT nanosheets were collected by the removal of PMMA with toluene: One was a single‐layer nanosheet with a thickness of 1.25 nm, and the other was a stacked sheet with an average thickness of 7.5 nm that may have consisted of six individual layers. Electron diffraction analysis revealed that if the individual layer of an MMT nanosheet were not a single crystal, it should contain an ultrathin layer of ice with a commonly occurring hexagonal phase. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5572–5579, 2006
Multicyclic polyethers by the polycondensation of 1,2‐ or 1,3‐dicyanotetrafluorobenzene with flexible diphenols
Authors: Kricheldorf Hans R. , Schellenberg Johann , Schwarz Gert 
Published: August 2006

Abstract1,2‐Dicyanotetrafluorobenzene (1,2‐DCTB) was polycondensed with various flexible diphenols in a molar ratio of 1:2, and experimental parameters such as the concentration and temperature were varied. Certain diphenols allowed a complete substitution of all CF bonds, so perfect multicyclic polyethers (BnCN, where B stands for bridge units, C represents cycles, and N is the degree of polymerization) were the main reaction products. Despite complete conversion, gelation was avoidable under optimized reaction conditions. However, in the case of 1,3‐dicyanotetrafluorobenzene (1,3‐DCTB), complete tetrasubstitution was not feasible with a feed ratio of 1:2. Yet, because of the inductive and mesomeric electronic interactions of all substituents in 1,3‐DCTB, the three CF groups in the ortho position with respect to the cyano groups were significantly more reactive than the fourth CF bond. Therefore, polycondensations with diphenols in a 3:2 feed ratio showed a relatively clean course, yielding soluble multicycles of structure Bn /2CN. All the multicyclic polyethers were amorphous and possessed molar mass distributions with polydispersities greater than 2. Heating with Cu2+ salts caused crosslinking of the multicycles derived from 1,2‐DCTB because of the formation of phthalocyanine complexes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5546–5556, 2006
Particle monolayer formation at the air–water interface by silica particle with well‐defined grafted polymer
Authors: Mouri Emiko , Okazaki Yoshitaka , Tatsuno Shintaro , Karakawa Hiroyuki , Yoshinaga Kohji 
Published: August 2006

AbstractParticle monolayer formation at the air–water interface by polymer‐grafted colloidal silica was investigated. Methyl methacrylate (MMA) was polymerized from initiative bromide groups at colloidal silica surface by atom transfer radical polymerization. We obtained polymer‐grafted silica particle (SiO2‐PMMA) with relative narrow polydispersity of PMMA. For the polymer‐grafted particle with high graft density, particle monolayer formation was confirmed by π‐A isotherm measurement and SEM observation. Interparticle distance was controllable by surface pressure. Furthermore, grafted polymer chains were suggested to be fairly extended at the air–water interface. However, for the polymer‐grafted particle with low graft density, monolayer structure on substrate showed aggregation and voids. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2789–2797, 2006
Thermal properties and crystalline structure of syndiotactic polystyrene‐based miscible blends
Authors: Chiu Fang‐Chyou , Lau Chun‐Saang 
Published: August 2006

AbstractThis work examined the effect of the pre‐melting temperature (Tmax) on the thermal properties and crystalline structure of four miscible syndiotactic polystyrene (sPS)‐based blends containing 80 wt % sPS. The counterparts for sPS included a high‐molecular‐weight atactic polystyrene [aPS(H)], a medium‐molecular‐weight atactic polystyrene [aPS(M)], a low‐molecular‐weight atactic polystyrene [aPS(L)], and a low‐molecular‐weight poly(styrene‐co‐α‐methyl styrene) [P(S‐co‐αMS)]. According to differential scanning calorimetry measurements, upon nonisothermal melt crystallization, the crystallization of sPS shifted to lower temperatures in the blends, and the shift followed this order of counterpart addition: P(S‐co‐αMS) > aPS(L) > aPS(M) > aPS(H). The change in Tmax (from 285 to 315 °C) influenced the crystallization of sPS in the blends to different degrees, depending on the counterpart's molecular weight and cooling rate. The change in Tmax also affected the complex melting behaviors of pure sPS and an sPS/aPS(H) blend, but it affected those of the other blends to a lesser extent. Microscopy investigations demonstrated that changing Tmax slightly affected the blends' crystalline morphology, but it apparently altered that of pure sPS. Furthermore, the X‐ray diffraction results revealed that the α‐form sPS crystal content in the blends generally decreased with an increase in Tmax, and it decreased with a decrease in the cooling rate as well. The blends showed a lower α‐form content than pure sPS; a counterpart of a lower molecular weight more effectively reduced the formation of α‐form crystals. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2798–2810, 2006
Study of the Daughter Products of Akardite‐II
Authors: Lussier Louis‐Simon , Bergeron Eric , Gagnon Hélène 
Published: August 2006

AbstractIn this work, five akardite‐II (AK‐II) daughter products were produced and isolated. Their respective MS, NMR, IR and UV spectra were recorded. These five products were positively identified as: N‐NO‐AK‐II, 2‐NO2‐AK‐II, 4‐NO2‐AK‐II, N‐NO‐2‐NO2‐AK‐II and N‐NO‐4‐NO2‐AK‐II. An HPLC method giving baseline separation of 6 AK‐II family products and 10 diphenylamine (DPA) family products is also described. Finally, preliminary results concerning the stability of AK‐II daughter products are discussed.
Alkali‐Dinitramide Salts Part 2: Oxidizers for Special Pyrotechnic Applications
Authors: Berger Beat P. , Mathieu Jörg , Folly Patrick 
Published: August 2006

AbstractAmmonium dinitramide is planned to be a substitute for commonly used oxidizers in rocket motor compositions. Different teams worldwide have already synthesized alkali salts of dinitramide and several times it was used as an oxidizer for pyrotechnic compositions containing boron as a reducing agent. In this paper the results of a systematic investigation to characterize the pyrotechnic redox systems titanium/potassium dinitramide and titanium/cesium dinitramide are presented and the data are compared. The heats of reaction as well as the burning rates of the redox system titanium/potassium dinitramide are higher than those of the redox system titanium/cesium dinitramide. Both systems show a moderate sensitivity to friction and electrostatic discharges. However the sensitivity of mixtures of both redox systems shows a very high sensitivity to impact. These sensitivities are in the range of pure HMX or pentaerythritol tetranitrate.
Radiative Ignition of Fine‐Ammonium Perchlorate Composite Propellants
Authors: Cain Jeremy , Brewster M. Quinn 
Published: August 2006

AbstractRadiative ignition of quasi‐homogeneous mixtures of ammonium perchlorate (AP) and hydroxyterminated polybutadiene (HTPB) binder has been investigated experimentally. Solid propellants consisting of fine AP (2 μm) and HTPB binder (~ 76/24% by mass) were ignited by CO2 laser radiation. The lower boundary of a go/no‐go ignition map (minimum ignition time vs. heat flux) was obtained. Opacity was varied by adding carbon black up to 1% by mass. Ignition times ranged from 0.78 s to 0.076 s for incident fluxes ranging from 60 W/cm2 to 400 W/cm2. It was found that AP and HTPB are sufficiently strongly absorbing of 10.6 μm CO2 laser radiation (absorption coefficient ≈250 cm−1) so that the addition of carbon black in amounts typical of catalysts or opacitymodifying agents (up to 1%) would have only a small influence on radiative ignition times at 10.6 μm. A simple theoretical analysis indicated that the ignition time‐flux data are consistent with in‐depth absorption effects. Furthermore, this analysis showed that the assumption of surface absorption is not appropriate, even for this relatively opaque system. For broadband visible/near‐infrared radiation, such as from burning metal/oxide particle systems, the effects of in‐depth absorption would probably be even stronger.
Crystal Structure, Thermal Decomposition and Properties of Cesium 3,5‐Dihydroxy‐2,4,6‐Trinitrophenolate
Authors: Chen Hongyan , Zhang Tonglai , Zhang Jianguo , Chen Chunchun 
Published: August 2006

AbstractA coordination polymer, cesium 3,5‐dihydroxy‐2,4,6‐trinitrophenolate ([Cs(DHTNP)]n), has been synthesized and its crystal structure determined. This crystal belongs to the monoclinic system with space group Pc. Each Cs+ is coordinated to 12 oxygen atoms from 8 different 3,5‐dihydroxy‐2,4,6‐trinitrophenolate (DHTNP−) anions, and each DHTNP− anion is coordinated with 8 Cs+ cations. The oxygen atoms of the phenolic hydroxyl group and from all of the nitro groups of the DHTNP− anion simultaneously bind to neighboring Cs+ ions. These DHTNP− molecular chains are interlaced, with the cesium atoms acting as knots, to create an infinite three‐dimensional network structure. The molecules are linked by electrostatic interactions and weak van der Waals, forces and also display intramolecular hydrogen bonding, which all enhance the thermal stability of the title compound. The thermal decomposition was studied using DSC, TG‐DTG and IR techniques. The results exhibit characteristics of a highly energetic compound that undergoes two highly exothermic decomposition reaction processes from 166 °C to 300 °C under the condition of a linear heating rate. The experimental sensitivity results indicate that [Cs(DHTNP)]n is quite sensitive to impact and friction.
Air Gap Effects in LX‐17
Authors: Souers P. Clark , Ault Stan , Avara Rex , Bahl Kerry L. , Boat Ron , Cunningham Bruce , Gidding Doug , Janzen Jim , Kuklo Denise , Lee Ron , Lauderbach Lisa , Weingart Richard C. , Wu Ben , Winer Kris 
Published: August 2006

AbstractThree experiments done over twenty years on gaps in LX‐17 are described. For the detonation front moving parallel to the gaps, jets of gas products were seen coming from the gaps at velocities 2 to 3 times greater than the detonation velocity. A case can be made that the jet velocity increased with gap thickness but the data are scattered. For the detonation front moving transverse to the gap, time delays were seen. The delays roughly increase with gap width, going from 0–70 ns at “zero gap” to around 300 ns at 0.5–1 mm gap. Larger gaps of up to 6 mm width almost certainly stopped the detonation, but this was not proved. Real‐time resolution of the parallel jets and determination of the actual re‐detonation or failure in the transverse case needs to be achieved in future experiments.
Relationship between the Bond Dissociation Energies and Impact Sensitivities of Some Nitro‐Explosives
Authors: Song Xiao‐Shu , Cheng Xin‐Lu , Yang Xiang‐Dong , He Bi 
Published: August 2006

AbstractThe bond dissociation energy (BDE) for removal of the NO2 group for eleven CHNO nitro‐containing explosive molecules is studied to find its correlation with impact sensitivity. The BDE for removal of the NO2 group in nitroaromatic molecules with nitro alkyl, and esters with nitro alkyl, is calculated using the B3LYP method of Density Functional Theory with the 6‐31G* basis set. The relationship between the impact sensitivities and the weakest C‐NO2 bond dissociation energy values is examined. The results indicate a nearly linear correlation between the impact sensitivity and the ratio of the BDE value to the total molecular energy.
Studies on RDX Influence on Performance Increase of Triple Base Propellants
Authors: Sanghavi Rakesh R. , Khire V. H. , Chakraborthy T. K. , Singh Amarjit 
Published: August 2006

AbstractConventional triple base propellants are currently used for high performance tank and field gun ammunition. The aim of the present study was to improve the chemical energy of the triple base propellant by partial replacement of picrite by RDX to achieve higher force constant (F) and lower specific heat ratio (γ). Details of theoretical and experimental studies carried out on six triple base propellant formulations are discussed in this paper. It can be concluded that partial replacement of picrite by RDX in the triple base propellant formulations achieved higher chemical energy as well as improved ballistic performance.
Solubility and Diffusivity of Polyethyl Acrylate in Supercritical Carbon Dioxide
Authors: Wallace Julie A. , Bell David A. 
Published: August 2006

AbstractAn alternative plastic‐bonded molding powder production process would use a polymeric binder dissolved in supercritical carbon dioxide rather than the liquid organic solvents currently used. This research investigated the solubility and diffusion coefficients of polyethyl acrylate, a potential binder, in supercritical carbon dioxide. Over the range of solvent conditions investigated, the dissolved polymer concentration was 0.036 wt% or less. A practical molding powder production process is not likely with such a dilute binder solution.