bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemistry with [18F]Fluoride Ion
Authors: Cai Lisheng , Lu Shuiyu , Pike Victor W. 
Published: May 2008

AbstractThe success of molecular imaging with positron‐emission tomography (PET) depends on the availability of selective molecular probes labeled with positron‐emitters, such asfluorine‐18 (t1/2 = 109.7 min). No‐carrier‐added (NCA) [18F]fluoride ion (18F–) is the primary reagent for the preparation of 18F‐labeled tracers in high specific activity. In this microreview, we survey current and advancing radiochemical methods and technologies for the use of NCA [18F]fluoride ion in the preparation of 18F‐labeled radiotracers for applications with PET. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Naphthyl‐Substituted Carbocations: From peri Interaction to Cyclization
Authors: Dyker Gerald , Hagel Marcel , Henkel Gerald , Köckerling Martin 
Published: May 2008

AbstractThe peri interaction of 1‐functionalized naphthalenes equipped with a triarylmethyl cation at the 8‐position has been studied because of the reversibility of the ring‐closing reaction, which was monitored closely by NMR spectroscopy in the case of the cyclic ammonium salt 5b. Carbocycle 4a and N‐heterocycle 5b did not exhibit any tendency for ring cleavage under various conditions, whereas the naphtho‐annulated furan 4c underwent reversible ring cleavage under strongly acidic conditions.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Isoflavone Glycosides: Synthesis and Evaluation as α‐Glucosidase Inhibitors
Authors: Wei Guo , Yu Biao 
Published: May 2008

AbstractOn the basis of the structure of 4′,7,8‐trihydroxyisoflavone 7‐O‐α‐D‐arabinofuranoside (namely A‐76202, 1), a Rhodococcus metabolite showing potent inhibitory activities againstthe α‐glucosidases of rat liver microsome (IC50 = 0.46 ng/mL), 26 analogs, each with minor variations at the sugar moiety and the isoflavone A and B rings, were readily synthesized. Notably, a new and efficient method was developed for the divergent synthesis of the B‐ring congeners of the isoflavone glycosides by using Suzuki–Miyaura coupling as the final step. Modifications at the sugar moiety and the isoflavone A ring significantly diminish the activity, whereas variations at the B ring are largely tolerated for retaining the potent α‐glucosidase inhibitory activity.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis of Oligophenylenevinylene Heptamers Substituted with Fullerene Moieties
Authors: Gégout Aline , Holler Michel , Figueira‐Duarte Teresa M. , Nierengarten Jean‐François 
Published: May 2008

AbstractOligophenylenevinylene (OPV) derivatives substituted with one or two fullerene subunits have been prepared starting from a fullerene carboxylic acid derivative and OPV heptamers bearing one or two alcohol functions. The electrochemical properties of the resulting C60‐OPV derivatives have been investigated by cyclic voltammetry. Whereas the fist reduction of both C60–OPV conjugates is centered on the C60 unit, the oxidation is centered on the OPV rod. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Association of depressive symptoms with bone mineral density in older men: a population‐based study
Authors: Laudisio Alice , Marzetti Emanuele , Cocchi Alberto , Bernabei Roberto , Zuccalà Giuseppe 
Published: May 2008

AbstractObjectiveThirty percent of hip fractures occur in men; nevertheless, the determinants of osteoporosis in men are unclear.MethodsWe assessed the association of ultrasound‐derived bone mineral density (UD‐BMD) with depressive symptoms in a population‐based study. We assessed the association of 30‐item Geriatric Depression Scale (GDS) score with the ultrasound‐derived T‐score, Z‐score, and Stiffness index in all 306 subjects aged 75 + living in Tuscania (Italy).ResultsIn multivariable linear regression analysis, GDS was associated among men with the ultrasound‐derived T‐score (β = −0.09; 95% CI = −0.15 to −0.03; p = 0.003), Z‐score (β = −0.07; 95% CI = −0.13 to −0.01; p = 0.032), and the Stiffness index (β = −0.90; 95% CI = −1.64 to −0.16; p = 0.018) after adjusting for potential confounders. No significant associations were observed in women. In linear discriminant analysis, the GDS score cutoff that best predicted osteoporosis was ≥19. Participants with mild to severe depressive symptoms had threefold increased probability of having an ultrasound‐derived T‐score < −2.5.ConclusionsDepressive symptoms are independently associated with all UD‐BMD parameters. As depression is a common feature among older populations, and because subjects with depression are infrequent users of preventive services, older men with depression should be prompted to undergo screening for osteoporosis. Conversely, assessment for depression should be performed in older men with diagnosis of osteoporosis. Copyright © 2008 John Wiley & Sons, Ltd.
Prevalence of depression and anxiety symptoms in elderly patients admitted in post‐acute intermediate care
Authors: Yohannes A. M. , Baldwin R. C. , Connolly M. J. 
Published: May 2008

AbstractObjectivesDepression and anxiety symptoms are common in medically ill older patients. We investigated the prevalence and predictors of depression and anxiety symptoms in older patients admitted for further rehabilitation in post acute intermediate care.DesignObservational cohort study.SettingAn intermediate care unit, North West of England.ParticipantsOne hundred and seventy‐three older patients (60 male), aged mean (SD) 80 (8.1) years, referred for further rehabilitation to intermediate care.MeasurementsDepression and anxiety symptoms were assessed by the Hospital Anxiety and Depression Scale, and severity of depression examined by the Montgomery Asberg Depression Rating Scale. Physical disability was assessed by the Nottingham Extended ADL Scale and quality of life by the SF‐36.ResultsSixty‐five patients (38%) were identified with depressive symptoms, 29 (17%) with clinical depression, 73 (43%) with anxiety symptoms, and 43 (25%) with clinical anxiety. 15 (35%) of the latter did not have elevated depression scores (9% of the sample). Of those with clinical depression, 14 (48%) were mildly depressed and 15 (52%) moderately depressed. Longer stay in the unit was predicted by severity of depression, physical disability, low cognition and living alone (total adjusted R2 = 0.24).ConclusionsClinical depression and anxiety are common in older patients admitted in intermediate care. Anxiety is often but not invariably secondary to depression and both should be screened for. Depression is an important modifiable factor affecting length of stay. The benefits of structured management programmes for anxiety and depression in patients admitted in intermediate care are worthy of evaluation. Copyright © 2008 John Wiley & Sons, Ltd.
A meta‐analytic study of changes in brain activation in depression
Authors: Fitzgerald Paul B. , Laird Angela R. , Maller Jerome , Daskalakis Zafiris J. 
Published: May 2008

AbstractThe article to which this erratum refers is published in this issue, Hum Brain Mapp (2008) 29:683–695. © 2008 Wiley‐Liss, Inc.
Optofluidic stretching of RBCs using single optical tweezers
Authors: Mohanty S. K. , Uppal A. , Gupta P. K. 
Published: May 2008

AbstractOur previous studies demonstrated a huge difference in rotational speed of trapped red blood cells under diseased condition, which was presumably attributed to change in viscoelastic properties. Here, we report use of single optical tweezers combined with viscous drag for stretching of the trapped cell. Significant differences were observed in the measured viscoelastic parameters of fresh and aged/malaria‐infected RBCs under hypotonic condition. The technique was also found to provide information about adhesion properties of RBCs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Oxidized low‐density lipoprotein acts synergistically with β‐glycerophosphate to induce osteoblast differentiation in primary cultures of vascular smooth muscle cells
Authors: Bear Mackenzie , Butcher Martin , Shaughnessy Stephen G. 
Published: May 2008

AbstractPrevious studies have localized osteoblast specific markers to sites of calcified atherosclerotic lesions. We therefore decided to use an established in vitro model of vascular calcification in order to confirm earlier reports of oxidized low‐density lipoprotein (oxLDL) promoting the osteogenic differentiation of vascular smooth muscle cells. Treatment of primary bovine aortic smooth muscle cells (BASMCs) with β‐glycerophosphate was found to induce a time‐dependent increase in osteoblast differentiation. In contrast, no effect was seen when BASMCs were cultured in the presence of oxLDL alone. However, when the BASMCs were cultured in the presence of both β‐glycerophosphate and oxLDL, β‐glycerophosphate's ability to induce osteoblast differentiation was significantly enhanced. In an attempt to resolve the mechanism by which this effect was occurring, we examined the effect of β‐glycerophosphate and oxLDL on several pathways known to be critical to the differentiation of osteoblasts. Surprisingly, β‐glycerophosphate alone was found to enhance Osterix (Osx) expression by inducing both Smad 1/5/8 activation and Runx2 expression. In contrast, oxLDL did not affect either Smad 1/5/8 activation or Runx2 activation but rather, it enhanced both β‐glycerophosphate‐induced Osx expression and osteoblast differentiation in an extracellular signal‐regulated kinase 1 and 2 (Erk 1 and 2) ‐dependent manner. When taken together, these findings suggest a plausible mechanism by which oxLDL may promote osteogenic differentiation and vascular calcification in vivo. J. Cell. Biochem. 105: 185–193, 2008. © 2008 Wiley‐Liss, Inc.
Mass transfer kinetics of neodymium(III) extraction by calix[4]arene carboxylic acid using a constant interfacial area cell with laminar flow
Authors: He Wenwei , Liao Wuping , Wang Weiwei , Li Deqian , Niu Chunji 
Published: May 2008

AbstractBACKGROUND: Thermodynamics and kinetics data are both important to explain the extraction property. In order to develop a novel separation technology superior to current extraction systems, many promising extractants have been developed including calixarene carboxylic acids. The extraction thermodynamics behavior of calix[4]arene carboxylic acids has been reported extensively. In this study, the mass transfer kinetics of neodymium(III) and the interfacial behavior of calix[4]arene carboxylic acid were investigated.RESULTS: The rate constant (Kao) becomes constant when the stirring speed was controlled between 250 rpm and 400 rpm. The activation energy (Ea) was calculated to be 21·41 kJ mol−1 or 88·17 kJ mol−1 (dependent on temperature) from the slope of log Kao against 1000/T. The linear relationship between the specific area and the extraction rate is the characteristic of an interfacial reaction control. The minimum bulk concentration of the extractant necessary to saturate the interface (Cmin) is lower than 4·19 × 10−4 mol L−1.CONCLUSION: The effect of stirring speed, temperature, and species concentration on the extraction rate demonstrates that the extraction regime depends on the extraction conditions. The chemical reaction control governs the extraction regime at temperatures below 303 K and a mixed control regime occurs when the temperature is between 303 K and 318 K. The probable locale for the chemical reaction is at the liquid–liquid interface and the rate equation is deduced to be: − d[Nd3+](a)/dt = kf[Nd3+](a)[H4A](o)0·727[H+](a)−0·978. The rate‐controlling step was suggested by the analysis of the experimental results. Copyright © 2008 Society of Chemical Industry
Modeling and optimization of lipase‐catalyzed synthesis of dilauryl adipate ester by response surface methodology
Authors: Rahman Mohd Basyaruddin Abdul , Chaibakhsh Naz , Basri Mahiran , Rahman Raja Noor Zaliha Raja Abdul , Salleh Abu Bakar , Radzi Salina Md 
Published: May 2008

AbstractBACKGROUND: Adipate esters are used as low‐temperature and low‐viscosity plasticizers for polyvinyl chloride and its copolymers. In this work, optimization of lipase‐catalyzed production of dilauryl adipate was carried out using response surface methodology (RSM) based on a four‐factor‐five‐level central composite rotatable design (CCRD). Immobilized lipase from Candida antarctica (Novozym 435) was used as catalyst in this reaction. Various reaction parameters affecting the synthesis of adipate ester, including alcohol/acid molar ratio, amount of enzyme, temperature and reaction time, were investigated.RESULTS: Statistical analysis showed that the amount of enzyme was less significant than the other three factors. The optimal conditions for the enzymatic reaction were obtained at 5.7:1 substrate molar ratio using 0.18 g of enzyme at 53.1 °C for 282.2 min. Under these conditions the esterification percentage was 96.0%.CONCLUSIONS: The results demonstrated that response surface methodology can be applied effectively to optimize the lipase‐catalyzed synthesis of adipate ester. The optimum conditions can obtained be used to scale up the process. Copyright © 2008 Society of Chemical Industry
Mixed‐mode hydrophilic interaction/cation‐exchange chromatography: Separation of complex mixtures of peptides of varying charge and hydrophobicity
Authors: Mant Colin T. , Hodges Robert S. 
Published: May 2008

AbstractMixed‐mode hydrophilic interaction/cation‐exchange chromatography (HILIC/CEX) was applied to the separation of two mixtures of synthetic peptide standards: (i) a 27‐peptide mixture containing three groups of peptides (each group containing nine peptides of the same net charge of +1, +2 or +3), where the hydrophilicity/hydrophobicity of adjacent peptides within the groups varied only subtly (generally by only a single carbon atom); and (ii) peptide pairs with the same composition but different sequences, where the sole difference between the peptides was the position of a single amino acid substitution. HILIC/CEX is essentially CEX chromatography in the presence of high levels of organic modifier (generally ACN). The present study demonstrated the dramatic effect of increasing ACN concentration (optimum levels of 60–80%, depending on the application) on the separation of both mixtures of peptides. The greater the charge on the peptides, the better the separation achievable by HILIC/CEX. In addition, HILIC/CEX separation of both the peptide mixtures used in the present study was shown to be superior to that of the more commonly applied RP‐HPLC mode. Our results highlight again the efficacy of HILIC/CEX as a peptide separation mode in its own right as well as an excellent complement to RP‐HPLC.
Method development for HILIC assays
Authors: Dejaegher Bieke , Mangelings Debby , Vander Heyden Yvan 
Published: May 2008

AbstractIn this review, method development for hydrophilic interaction LC (HILIC) is highlighted. HILIC is a chromatographic technique that uses aqueous‐organic solvent mobile phases with a high organic‐solvent fraction, and a hydrophilic stationary phase. It is mainly applied for the separation of polar and hydrophilic compounds. Method development, in general, can be done uni‐ or multivariately. In the univariate approach, the factors that are expected to potentially affect the separation of the compounds will be examined sequentially and one‐at‐a‐time. All HILIC methods found in the literature were developed in this way. For these methods, the analytes, the considered factors, the selected responses, and the finally chosen experimental conditions are discussed in this review. Where examined, the method validation and the comparison with other analytical assay methods is also described. For the multivariate method‐development approach, which is based on the use of experimental designs, only a possible strategy is presented, because of the lack of relevant publications in the literature.
Separation properties of novel and commercial polar stationary phases in hydrophilic interaction and reversed‐phase liquid chromatography mode
Authors: Wu JunYan , Bicker Wolfgang , Lindner Wolfgang 
Published: May 2008

AbstractFour novel nonionic polar stationary phases were synthesised by anchoring first 2‐mercaptoethanol and 1‐thioglycerol, respectively, onto vinylised silica (ME and TG packings) followed by an on‐phase oxidation with excess hydrogen peroxide in aqueous medium which yielded sulphoxide analogues of the embedded sulphide groups, i. e. oxidised 2‐mercaptoethanol (MEO) and oxidised 1‐thioglycerol (TGO) packings. Chromatographic characteristics of these stationary phases were evaluated comparatively to three commercial so‐called ‘diol’ columns. U‐shaped response curves of retention factors of adenosine and guanosine with hydro‐organic eluents containing 5–95% v/v ACN as well as noticeable CH2‐increment selectivity demonstrated multimodal separation capabilities of the developed amphiphilic materials, i. e. columns can be operated both in hydrophilic interaction chromatography (HILIC) and in RP mode. Although the selector ligands were physico‐chemically related, considerably differing retention and selectivity patterns were observed in the HILIC mode. Thereby the introduction of additional hydroxyl groups in the chromatographic ligand resulted in selectivity increments that were different from those obtained by sulphur oxidation. For example, a set of five vitamins delivered five different elution orders with the overall seven columns. A close examination of HILIC separations of nucleobases and nucleosides on the developed packings revealed that (i) the amount of ACN in the eluent adopts a pivotal role in adjusting retention, (ii) the linearity of the relationship log (retention factor) versus log (volume fraction of water in the eluent) increases with phase polarity in the range of 5–40% v/v water, (iii) the slopes are higher with solutes having more polar interactive sites, (iv) the van't Hoff plots are linear (range 15–45°C) with negative retention enthalpy values ΔH (–4.5 to –14.5 kJ/mol) and (v) the –ΔH values tend to be higher with more polar phases and more polar analytes. Based on these data the HILIC retention mechanism is described to be composed of both partitioning and adsorption processes. Distinct types of polar interactive sites in the chromatographic ligands may generate mixed‐mode HILIC separation conditions that may additionally be superimposed by surface silanol contributions.
Fast hydrophilic interaction liquid chromatographic separations on bonded zwitterionic stationary phase
Authors: Appelblad Patrik , Jonsson Tobias , Jiang Wen , Irgum Knut 
Published: May 2008

AbstractSeparation science is an art of obtaining adequate resolution of the desired compounds in minimum time, and with minimum effort in terms of sample preparation and data evaluation. In LC, where selectivity is a main driving force for separation, the availability of different separation modes capable of operating at high flow rates is a way to make combined optimal use of selectivity, efficiency, and speed. The separation of polar and hydrophilic compounds is problematic in RP LC due to the poor retention. Hydrophilic interaction liquid chromatography (HILIC) is a more straightforward separation mode to address this problem. Herein, it is shown that separations in HILIC mode are equally efficient as for RP, providing a potential for very fast separations on short columns. This is not only facilitated by the low viscosity of the mobile phase compositions used, compared to typical RP eluents, but also due to higher column permeability. To exemplify this, baseline separations of uracil and cytosine are shown in less than 4 s and of Tamiflu® and its main metabolite in less than 40 s, both under isocratic conditions. HILIC must therefore be considered having potential for high throughput purposes, and being an attractive candidate as the second separation dimension in 2‐D HPLC.
Phase Separation and Properties of UV‐Curable Polyurethane/Zirconia Nanocomposite Coatings
Authors: Zhou Shuxue , Wu Limin 
Published: May 2008

AbstractTransparent zirconia (ZrO2) nanocrystal dispersions in butyl acetate (BAc) or tetrahydrofuran (THF) were prepared by functionalizing zirconia nanocrystals, synthesized from a solvothermal reaction of zirconium (IV) isopropoxide isopropyl alcohol complex in benzyl alcohol, with 3‐methacryloxypropyltrimethoxysilane (MPS), and were embedded into UV‐curable polyurethane (PU) coatings. It was found that the ZrO2 concentration was the dominating factor influencing the transparency of the ZrO2 dispersion, while the molar ratio of MPS to ZrO2 was rather efficient in adjusting the amount of MPS attached. Phase separation of the ZrO2 nanocrystals in polyurethane coatings was observed, and was strongly related to the MPS‐modified ZrO2 (MPS‐ZrO2) content and the amount of MPS chemically bonded. The phase separation of the PU/ZrO2 nanocomposite coatings appeared more seriously for higher MPS‐ZrO2 content and higher amounts of MPS attached; thus the transparency of the nanocomposite coatings was lower. However, completely transparent PU/ZrO2 nanocomposite coatings could be still achieved even with a ZrO2 content up to 7.5 wt.‐% using a ZrO2/BAc dispersion. Improvements in pendulum hardness, microhardness and scratch resistance of the polyurethane coatings via addition of MPS‐ZrO2 were demonstrated, but were not remarkable because of the low cross‐linking efficiency of the MPS‐ZrO2 nanoparticles resulting from the poor compatibility of the MPS‐ZrO2 nanoparticles with the pure PU oligomers.magnified image
Characterizing PSPACE with pointers
Authors: Oitavem Isabel 
Published: May 2008

AbstractThis paper gives an implicit characterization of the class of functions computable in polynomial space by deterministic Turing machines – PSPACE. It gives an inductive characterization of PSPACE with no ad‐hoc initial functions and with only one recursion scheme. The main novelty of this characterization is the use of pointers (also called path information) to reach PSPACE. The presence of the pointers in the recursion on notation scheme is the main difference between this characterization of PSPACE and the well‐known Bellantoni‐Cook characterization of the polytime functions – PTIME. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ionized‐Air‐Treated Curaua Fibers as Reinforcement for Phenolic Matrices
Authors: Trindade Wanderson Gonçalves , de Paiva Jane Maria Faulstich , Leão Alcides Lopes , Frollini Elisabete 
Published: May 2008

AbstractCuraua fibers were treated with ionized air to improve the fiber/phenolic matrix adhesion. The treatment with ionized air did not change the thermal stability of the fibers. The impact strength increased with increase in the fiber treatment time. SEM micrographs of the fibers showed that the ionized air treatment led to separation of the fiber bundles. Treatment for 12 h also caused a partial degradation of the fibers, which prompted the matrix to transfer the load to a poorer reinforcing agent during impact, thereby decreasing the impact strength of the related composite. The composites reinforced with fibers treated with ionized air absorbed less water than those reinforced with untreated fibers.magnified image
Variational principles for symmetric bilinear forms
Authors: Danciger Jeffrey , Garcia Stephan Ramon , Putinar Mihai 
Published: May 2008

AbstractEvery compact symmetric bilinear form B on a complex Hilbert space produces, via an antilinear representing operator, a real spectrum consisting of a sequence decreasing to zero. We show that the most natural analog of Courant's minimax principle for B detects only the evenly indexed eigenvalues in this spectrum. We explain this phenomenon, analyze the extremal objects, and apply this general framework to the Friedrichs operator of a planar domain and to Toeplitz operators and their compressions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)