bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hierarchical Structure‐Within‐Structure Morphologies in A2‐star‐(B‐alt‐C) Molecules
Authors: Huang Ching‐I , Chen Chih‐Ming 
Published: October 2007

AbstractWe employ dissipative particle dynamics (DPD) to examine the self‐assembly behavior of A2‐star‐(B‐alt‐C) molecules. We successfully observe various types of hierarchical structure‐within‐structures, such as A‐formed spheres in the matrix formed by B and C alternating layers, hexagonally packed A‐formed cylinders in the matrix with B and C segregated layers, B and C alternating layers‐within‐lamellae, coaxial B and C alternating domains within hexagonally packed BC‐formed cylinders in the A‐matrix, and co‐centric BC‐alternating domains within BC‐formed spheres in the A‐matrix, by increasing the A composition. Generally speaking, the small length‐scale B and C segregated domains are in parallel to the large length‐scale structures. This hierarchical periodicity along the same axis as well as the various characteristic structures, that the A2‐star‐(B‐alt‐C) copolymers display, are quite different from those in A‐block‐(B‐graft‐C) coil‐comb copolymers. Moreover, it is interesting to find that when the copolymer chain length increases, though the hierarchical structure type is maintained, the number of small length‐scale lamellae that can form within the large length‐scale structure increases. These hierarchical structures under various compositions are reported theoretically for the first time in the copolymer systems consisting of the alternating blocks, and are in good agreement with the most recent experimental work by Matsushita and co‐workers (Macromolecules 2007, 40, 4023).
Different Protonation Equilibria of 4‐Methylimidazole and Acetic Acid
Authors: Gu Wei , Helms Volkhard 
Published: October 2007

AbstractDynamic protonation equilibria in water of one 4‐methylimidazole molecule as well as for pairs and groups consisting of 4‐methylimidazole, acetic acid and bridging water molecules are studied using Q‐HOP molecular dynamics simulation. We find a qualitatively different protonation behavior of 4‐methylimidazole compared to that of acetic acid. On one hand, deprotonated, neutral 4‐methylimidazole cannot as easily attract a freely diffusing extra proton from solution. Once the proton is bound, however, it remains tightly bound on a time scale of tens of nanoseconds. In a linear chain composed of acetic acid, a separating water molecule and 4‐methylimidazole, an excess proton is equally shared between 4‐methylimidazole and water. When a water molecule is linearly placed between two acetic acid molecules, the excess proton is always found on the central water. On the other hand, an excess proton in a 4‐methylimidazole‐water‐4‐methylimidazole chain is always localized on one of the two 4‐methylimidazoles. These findings are of interest to the discussion of proton transfer along chains of amino acids and water molecules in biomolecules.
Orientation and Arrangement of Octaruthenium Supramolecules with Alkyl Chains on Graphite
Authors: Shieh Dong‐Lin , Lin Yi‐Shiue , Shiu Kom‐Bei , Lin Jong‐Liang 
Published: October 2007

AbstractThe self‐assemblies of octaruthenium grid‐type supramolecules, {[Ru2(CO)4(NH2C16H33)2](μ‐O2CCO2)}4, on highly oriented pyrolytic graphite (HOPG) in air and in 1‐phenyloctane were studied by scanning tunneling microscopy (STM). The surface supramolecules are arranged into rows in which the metal cores are linearly packed and the alkyl chains are parallel to the surface. With the aid of theoretical calculations in the framework of density functional theory, the electronic origin of the tunneling in the measured STM images is discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Aldehyde N,N‐Dialkylhydrazones as Neutral Acyl Anion Equivalents: Umpolung of the Imine Reactivity
Authors: Brehme Rainer , Enders Dieter , Fernandez Rosario , Lassaletta José M. 
Published: October 2007

AbstractThe isoelectronic replacement of the α‐carbon of enamines by nitrogen leads to the corresponding hydrazones, and thus, they can be termed “aza‐enamines”. Hence, aldehyde N,N‐dialkylhydrazones enable analogous electrophilic substitutions at the imine carbon that corresponds to the β‐carbon of enamines. In addition, after hydrolysis of the product hydrazones to the parent ketones or aldehydes, these reactions constitute an umpolung of the classical carbonyl reactivity and overall a nucleophilic acylation or formylation. This review covers the aza‐enamine chemistry from its very beginning in the late 1960s up to this year. In the first part, reactions of aromatic, aliphatic, and heterocyclic aldehyde N,N‐dialkylhydrazones with highly reactive substrates such as the Vilsmeier and Mannich reagents, sulfonyl isocyanates, perfluoroacetic anhydride, and inorganic electrophiles such as halogens and phosphorus tribromide are described. The hydrazones of α,β‐unsaturated aldehydes react as vinylogous aza‐enamines at the terminal carbon providing unsaturated aldehydes. As electron‐rich dienes and dienophiles, they also form Diels–Alder adducts and thus interesting N‐heterocycles. The second part covers carbon–carbon bond formations of the sterically less‐demanding formaldehyde N,N‐dialkylhydrazones with synthetically very useful electrophiles such as various Michael acceptors and carbonyl compounds. Formaldehyde SAMP‐hydrazone and related derivatives generally give excellent asymmetric inductions. Finally, first organocatalytic versions of the aza‐enamine chemistry are presented. In summary, the rich chemistry of aldehyde N,N‐dialkylhydrazones as neutral acyl anion, formyl anion, and cyanide equivalents is demonstrated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Stereoselective Formation of a Chiral Ether by Intramolecular O–H Insertion Reaction of a Metal Carbenoid Generated from Diazoacetoacetate
Authors: Im Chun Young , Okuyama Tadashi , Sugimura Takashi 
Published: October 2007

AbstractIntermolecular O–H insertion reactions of rhodium carbenoids generated from chiral diazoacetoacetates are less efficient and less stereoselective than the reactions of those generated from the corresponding phenyldiazoacetates. Nevertheless, when the diazoacetoacetate is connected to a phenolic moiety through a 2,4‐pentanediol tether, the carbenoid generated shows a high potential in both efficiency and stereoselectivity during the intramolecular O–H insertion reaction to give a cyclic ether in up to 88 % diastereomeric excess (de) in quantitative yield. The de value depends on the structure of the tether, but is independent of the catalyst employed. The isomerization of the cyclic ether has been studied under the conditions of equilibrium and kinetic protonation of the corresponding enolate. The similarity between the de values obtained by insertion and those obtained under equilibrium suggests that the rhodium catalyst is eliminated during the early stages of the O–H insertion reaction and that proton transfer, which determines thestereoselectivity, occurs after the elimination of the rhodium metal, independent of the stereochemistry of the initial addition.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Quaternary ammonium chitosan derivative dynamic coating for the separation of veterinary sulfonamide residues by CE with field‐amplified sample injection
Authors: Ma Ming , Zhang Hua‐Shan , Xiao Ling‐Yan , Xiao Ling , Wang Peng , Cui Hai‐Rong , Wang Hong 
Published: October 2007

AbstractA quaternary ammonium chitosan, 2‐hydroxypropyltrimethylammonium chloride chitosan (HACC), has been developed for the dynamic coating material in CE for the first time. It presented many advantages such as favorable water solubility, satisfactory coating efficiency, and EOF toward the anode at pH >7.0. Using the modified fused‐silica capillary, sulfonamides (SAs), an important group of veterinary drugs, were separated and detected by CE combined with field‐amplified sample injection (FASI). The LODs of sulfonamides with UV detection were less than 0.5 ng/mL. The proposed method has been applied to the determination of veterinary sulfonamide residues in samples such as chicken, beef, and honey with fast separation (15 sulfonamides within 20 min), low LODs (0.1–0.5 ng/mL), and good reliability compared to the criteria of China (GB/T 18932.17‐2003).
NACE for the analysis of acrylamide in food
Authors: Başkan Selda , Erim F. Bedia 
Published: October 2007

AbstractAn NACE method was developed for the quantitative determination of acrylamide in processed food. The method is premised on the modification of the aqueous acid–base character of acrylamide in an organic solution. Acrylamide, which is a polar molecule in aqueous solution, in a low‐pH environment in ACN acquires a proton, and thereby migrates under its own electrophoretic mobility in CE. Thus, nonaqueous separation of acrylamide was achieved by employing 30 mmol/L HClO4 in ACN as the running electrolyte. The detection limit of the method for acrylamide was found as 0.041 mg/L using UV detection at 200 nm. The run‐to‐run and day‐to‐day precisions for the corrected peak areas were calculated as 1.65 and 3.90%, respectively. The applicability of the method has been demonstrated by analyzing acrylamide in the samples of potato chips and French fries. The method is simple, rapid, inexpensive, and widely applicable for the determination of acrylamide in food samples.
Penalty formulation for postfilling analysis during injection molding
Authors: Kang Sung Yong , Kim Sun Kyoung , Lee Woo Il 
Published: October 2007

AbstractWe propose an approximate method that can simulate the packing stage during the injection molding using the penalty parameter method. In order to account for the compressibility effect, an update scheme based on similarity between the slightly compressible and the penalty formulations is proposed. The method allows for solving the entire injection molding process using a single algorithm with the penalty method in spite of the transition from the incompressible regime during the filling stage into the compressible regime for the packing stage. Several test cases have been presented to prove the validity of the method. It has been shown that the accuracy of the proposed method is identical to that of the mixed method. Copyright © 2007 John Wiley
& Sons, Ltd.
Emergence of NMDAR‐independent long‐term potentiation at hippocampal CA1 synapses following early adolescent exposure to chronic intermittent ethanol: Role for sigma‐receptors
Authors: Sabeti Jilla , Gruol Donna L. 
Published: October 2007

AbstractAdolescent humans who abuse alcohol are more vulnerable than adults to the development of memory impairments. Memory impairments often involve modifications in the ability of hippocampal neurons to establish long‐term potentiation (LTP) of excitatory neurotransmission; however, few studies have examined how chronic ethanol exposure during adolescence affects LTP mechanisms in hippocampus. We investigated changes in LTP mechanisms in hippocamal slices from rats exposed to intoxicating concentrations of chronic intermittent ethanol (CIE) vapors in their period of early‐adolescent (i.e., prepubescent) or late‐adolescent (i.e., postpubescent) development. LTP was evaluated at excitatory CA1 synapses in hippocampal slices at 24 h after the cessation of air (control) or CIE vapor treatments. CA1 synapses in control slices showed steady LTP following induction by high‐frequency stimulation, which was fully dependent on NMDAR function. By contrast, slices from early‐adolescent CIE exposed animals showed a compound form of LTP consisting of an NMDAR‐dependent component and a slow‐developing component independent of NMDARs. These components summated to yield LTP of robust magnitude above LTP levels in age‐matched control slices. Bath‐application of the σ‐receptor antagonist BD1047 and the neuroactive steroid pregnenolone sulfate, but not acute ethanol application, blocked NMDAR‐independent LTP, while leaving NMDAR‐dependent LTP intact. Analysis of presynaptic function during NMDAR‐independent LTP induction demonstrated increased presynaptic function via a σ‐receptor‐dependent mechanism in slices from early‐adolescent CIE‐exposed animals. By contrast, CIE exposure after puberty onset in late‐adolescent animals produced decrements in LTP levels. The identification of a role for σ‐receptors and neuroactive steroids in the development of NMDAR‐independent LTP suggests an important pathway by which hippocampal synaptic plasticity, and perhaps memory, may be uniquely altered by chronic ethanol exposure during the prepubescent phase of adolescent development. © 2007 Wiley‐Liss, Inc.
Pharmacotherapy in the community‐based treatment of children with bipolar I disorder
Authors: Jerrell Jeanette M. 
Published: October 2007

AbstractObjectiveTo examine the services and medications received, and psychosocial functioning changes over time of children and adolescents with bipolar I disorder in a public mental health system.MethodMedical records were reviewed for 82 patients, 6–17 years of age, diagnosed with bipolar I disorder, and newly admitted to one public mental health system between 1 July 2003 and 30 June 2004. A retrospective cohort design was employed, with an 18‐month follow‐up period.ResultsOne‐third of the patients dropped out treatment within a few months. The psychosocial functioning ratings of patients who remained in treatment improved over time on several dimensions (total, school/work, behavior toward others). Children and adolescents prescribed both a mood stabilizer and an atypical antipsychotic medication regimen (35%) were rated as higher functioning on self‐harm behavior and mood/emotions by clinical staff, but their improvement could not be attributed directly to the pharmacotherapy in this small cohort.ConclusionCommunity‐based pharmacotherapy for children and adolescents with bipolar I disorder does not differ substantially from the extant literature, given the complexity and severity of these cases, and may lead to improvement for children and adolescents who remain in treatment. Copyright © 2007 John Wiley & Sons, Ltd.
MMTV‐EGF receptor transgene promotes preneoplastic conversion of multiple steroid hormone‐responsive tissues
Authors: Marozkina Nadzeya V. , Stiefel Steven M. , Frierson Henry F. , Parsons Sarah J. 
Published: October 2007

AbstractCorrelative analyses of tumors and patient‐derived cell lines of the human reproductive system suggest that overexpression of EGF contributes to the oncogenic phenotype. However, it is unclear at what stage in disease overexpression of the EGFR is most critical. To assess its role as an initiator of reproductive tissue tumor development, transgenic mice were derived with mouse mammary tumor virus (MMTV)‐regulated overexpression of the human EGFR. Although elevated expression of the EGFR in hormonally responsive tissues was observed, only one EGFR transgenic mouse developed a visible tumor over a 2‐year period. However, of 12 females monitored over the same time, hyperplasia, hypertrophy, or slight dysplasia was found in mammary glands of 55% of the animals examined, in the uterus or uterine horn of 89%, and in ovaries or oviducts of 100%. None of the reproductive tissues of the male transgenic animals or age‐matched, normal mice displayed these changes. These results revealed a role for the EGFR in the initiation of ovarian and uterine cancer and supported previous studies in breast cancer that the receptor can contribute to the neoplastic process in a significant albeit incremental way. J. Cell. Biochem. 103: 2010–2018, 2008. © 2007 Wiley‐Liss, Inc.
Opposing effects of curcuminoids on serum stimulated and unstimulated angiogenic response
Authors: Kiran M.S. , Kumar V.B. Sameer , Viji R.I. , Sherin G.T. , Rajasekharan K.N. , Sudhakaran P.R. 
Published: October 2007

AbstractCurcumin is known to be a potent wound healer. Despite this, studies on curcumin using certain model systems have shown it to be anti‐angiogenic. Results of the present investigations suggest that curcumin causes opposing effects on angiogenesis in serum stimulated and unstimulated conditions. The evidence in support of this are: (a) in serum free conditions, curcumin promoted sprouting in rat aortic ring, increased vascular density in CAM and induced morphological changes indicative of angiogenic phenotype in HUVECs and rat aortic endothelial cells in culture, (b) increased the expression of biochemical markers of angiogenesis such as CD 31, E‐selectin, VEGF and VEGFR‐2 in HUVECs on treatment with curcumin, and (c) supplementation of curcumin along with serum caused decrease in CD 31 and E‐selectin levels, downregulation of VEGF, angiopoietin‐1 and VEGFR‐2 and delayed formation of capillary network‐like structure. Proangiogenic effect of the individual components of the natural curcumin differed and the presence of the three components in the natural mixture has a synergistic effect. Effect of curcuminoids in the absence of serum appears to depend on VEGF as (a) anti‐VEGF antibody blocked the effect of curcuminoids (b) curcuminoids caused decrease in PAR modification of VEGF increasing its biological activity. Treatment with curcuminoids in serum‐free conditions resulted in activation of PI3K‐Akt pathway; but in serum‐supplemented condition, curcuminoids caused inhibition of the MAPK pathways thereby inhibiting the expression of angiogenic phenotype. These results suggest that PI3K‐Akt and MAPK pathways involved in the expression of angiogenic phenotype respond differently to the extracellular microenvironment. J. Cell. Physiol. 215: 251–264, 2008. © 2007 Wiley‐Liss, Inc.
Musculoskeletal underpinnings to differences in killing behavior between North American accipiters (Falconiformes: Accipitridae) and falcons (Falconidae)
Authors: Sustaita Diego 
Published: October 2007

AbstractAccipiters (Accipiter spp.) and falcons (Falco spp.) both use their feet to seize prey, but falcons kill primarily with their beaks, whereas accipiters kill with their feet. This study examines the mechanistic basis to differences in their modes of dispatching prey, by focusing on the myology and biomechanics of the jaws, digits, and distal hindlimb. Bite, grip, and distal hindlimb flexion forces were estimated from measurements of physiological cross‐sectional area (PCSA) and indices of mechanical advantage (MA) for the major jaw adductors, and digit and tarsometatarsal flexors. Estimated bite force, total jaw adductor PCSA, and jaw MA (averaged over adductors) tended to be relatively and absolutely greater in falcons, reflecting their emphasis on biting for dispatching their prey. Differences between genera in estimated grip force, total digit flexor PCSA, and digit MA (averaged over inter‐phalangeal joints and digits) were not as clear‐cut; each of these parameters scaled positively allometric in accipiters, which may reflect the scaling of both prey size, and the proportion of mammalian prey consumed by this lineage with increasing body size. Estimated tarsometatarsal force was greater in falcons than in accipiters, due to their greater MA, which may reflect selection for incurring greater forces during prey strikes. Conversely, the comparatively lower tarsometatarsal MA in accipiters reflects their capacity for greater foot speed potentially necessary for grasping elusive prey. Thus, this study elucidates how differences in jaw and hindlimb musculoskeletal morphology of accipiters and falcons are reflected in differences in their killing modes, and through differences in their force‐generating capacities. J. Morphol., 2008. © 2007 Wiley‐Liss, Inc.
The morphology and evolutionary significance of the ciliary fields and musculature among marine bryozoan larvae
Authors: Santagata Scott 
Published: October 2007

AbstractDespite the embryological and anatomical disparities present among lophotrochozoan phyla, there are morphological similarities in the cellular arrangements of ciliated cells used for propulsion among the nonfeeding larval forms of kamptozoans, nemerteans, annelids, mollusks, and bryozoans. Evaluating whether these similarities are the result of convergent selective pressures or a shared (deep) evolutionary history is hindered by the paucity of detailed cellular information from multiple systematic groups from lesser‐known, and perhaps, basal evolutionary phyla such as the Bryozoa. Here, I compare the ciliary fields and musculature among the major morphological grades of marine bryozoan larvae using light microscopy, SEM, and confocal imaging techniques. Sampling effort focused on six species from systematic groups with few published accounts, but an additional four well‐known species were also reevaluated. Review of the main larval types among species of bryozoans and these new data show that, within select systematic groups of marine bryozoans, there is some conservation of the cellular arrangement of ciliary fields and larval musculature. However, there is much more morphological diversity in these structures than previously documented, especially among nonfeeding ctenostome larval types. This structural and functional diversification reflects species differences in the orientation of the apical disc during swimming and crawling behaviors, modification of the presumptive juvenile tissues, elongation of larval forms in the aboral–oral axis, maximizing the surface area of cell types with propulsive cilia, and the simplification of ciliary fields and musculature within particular lineages due to evolutionary loss. Considering the embryological origins and functional plasticity of ciliated cells within bryozoan larvae, it is probable that the morphological similarities shared between the coronal cells of bryozoan larvae and the prototrochal cells of trochozoans are the result of convergent functional solutions to swimming in the plankton. However, this does not rule out cell specification pathways shared by more closely related spiralian phyla. Overall, among the morphological grades of larval bryozoans, the structural variation and arrangement of the main cell groups responsible for ciliary propulsion have been evolutionarily decoupled from the more divergent modifications of larval musculature. The structure of larval ciliary fields reflects the functional demands of swimming and substrate exploration behaviors before metamorphosis, but this is in contrast to the morphology of larval musculature and presumptive juvenile tissues that are linked to macroevolutionary differences in morphogenetic movements during metamorphosis. J. Morphol., 2008. © 2007 Wiley‐Liss, Inc.