bluuebunny/crossref_metadata_2025 huggingface dataset:
Sex differences in vocal patterns in the northern muriqui (Brachyteles hypoxanthus)
Authors: Arnedo Luisa F. , Mendes Francisco D.C. , Strier Karen B.
Published: November 2009

We investigated whether sex differences in spatial dynamics correlate with rates of staccato and neigh vocalizations in northern muriquis (Brachyteles hypoxanthus) at the Reserva Particular do Patrimônio Natural–Feliciano Miguel Abdala, Minas Gerais, Brazil. A total of 2,727 10 min focal subject samples were collected on 32 adult females and 31 adult males between April 2007 and March 2008. Compared with males, females spent a significantly lower proportion of their time in proximity to other group members and gave staccatos at significantly higher rates while feeding, resting, and traveling. Conversely, males emitted neigh vocalizations at significantly higher rates than females when feeding and resting only. Both sexes gave significantly more staccatos when feeding than when they were engaged in other activities, but their respective rates of neighs did not vary across activities. Both females and males emitted staccato vocalizations at significantly higher rates during times of the year when preferred foods were scarce, but no seasonal differences in the rates of neigh vocalizations were observed in either sex. Females and males showed a reduction in the number of neighbors following staccato vocalizations and an increase in the number of neighbors following neigh vocalizations. Our findings of sex differences in the rates of staccato and neigh vocalizations and the effects of these vocalizations on interindividual spacing are consistent with sex differences in spatial dynamics, and confirm the role of vocal communication in mediating spatial associations in this species. Am. J. Primatol. 72:122–128, 2010. © 2009 Wiley‐Liss, Inc.
Activated sludge dewatering in a filtration compression cell: deviations in comparison to the classical theory
Authors: Raynaud M. , Vaxelaire J. , Heritier P. , Baudez J.‐C.
Published: November 2009

Wastewater treatment plants produce a residue that must be usually dewatered to reduce volume before handling and disposal, but operating parameters may impact activated sludge dewatering. On the one hand, the results obtained from tests conducted in the filtration–compression cell (FCC) show an impact of the initial slurry concentration and its amount on filtration kinetic. However, a scaling with respect to the initial amount enables an interesting representation of these data. On the other hand, the working pressure does not modify filtration kinetics, but it has a significant effect on the expression stage. Larger amount of filtrate is extracted when a higher pressure is applied for the expression stage. Moreover, the squeezing ability of the filter cake greatly depends on the time when the pressure step is applied. All these results are not fully modelled by the current theories, and Ruth's equation, which is commonly used, has its limitations in being able to properly describe activated sludge filtration. Because the visco‐elastic behaviour of filter cake is generally not considered by classical dewatering models, further work is needed to take into account this phenomenon. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
Effect of fiber orientation on Mode I fracture toughness of CFRP
Authors: Miyagawa Hiroaki , Sato Chiaki , Ikegami Kozo
Published: November 2009

The effect of fiber orientations on fracture toughness of carbon fiber reinforced plastics (CFRP) in Mode I loading was investigated using double cantilever beam (DCB) specimens, based on mesoscopic mechanics. Mesoscopic interlaminar fracture toughness of 0//0 interphase of CFRP was evaluated with mesoscopic finite element models using experimental data. The fracture surface roughness was observed by confocal laser scanning microscopy. Then the mesoscopic interlaminar fracture toughness of CFRP was correlated with the fracture surface roughness. Additionally, the change of the Mode I macroscopic fracture toughness of CFRP was experimentally measured with changing the numbers of 0 and ±θ layers of DCB specimens. The correlation between the fracture toughness of 0//0 and θ//−θ interphases was discussed and a novel procedure was proposed to predict the macroscopic fracture toughness of θ//−θ interphase using finite element method (FEM). The fracture toughness of θ//−θ interphase analyzed by FEM was finally compared with the experimental results to verify the proposed prediction procedure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Studies on synthesis and characterization of N‐alkyl terephthalamides using different amines from polyethylene terephthalate waste
Authors: Soni R. K. , Singh Swati , Dutt Krishna
Published: November 2009

This study deals with the degradation of polyethylene terephthalate (PET) waste through aminolysis with various amines. All of these degradation experiments were carried out at ambient temperature and at normal pressure. Although PET is known to be recycled in many ways, but still there is a need of development of other environment friendly recycling techniques. The amines used to study the degradation of PET waste were namely methylamine, ethylamine, and n‐butyl amine, respectively where the degradation of PET waste completes in 45 days. The aminolyzed products so obtained were characterized by using various conventional techniques such as spectroscopic techniques namely IR, NMR, and simultaneous differential scanning calorimeter (DSC). In the present research work, a useful method of PET recycling by using various amines was successfully established. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
A reactive polymer for toughening epoxy resin
Authors: Kuan Hsu‐Chiang , Dai Jia‐Bin , Ma Jun
Published: November 2009

Epoxy resins are hardly toughened by low weight content of tougheners. In this study, 5 wt % polyurea was adopted to significantly toughen piperidine‐cured epoxy, as fracture toughness improved from 0.78 to 1.98 MPa m1/2. We focused on the reactions and morphology evolution of epoxy/polyurea mixture. The polyurea molecular weight was reduced by the exchange reactions of polyurea with epoxy during mixing, as evidenced by gel permeation chromatograph and Fourier transform infrared spectroscopy. As a result, epoxy molecules were chemically bonded with polyurea, improving particle content and interface thickness. Transmission electron microscope observation shows that (a) polyurea in situ formed nanoparticles in matrix which subsequently aggregate into micron‐sized particles of thick interface with matrix; and (b) the particles became less stainable with increasing the mixing time, because the reactions promoted high levels of crosslink density of the particles which were thus more resistant to the diffusion of staining chemicals. Longer mixing time improved, obviously, the fracture toughness of epoxy/polyurea composite. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis of a novel series of propargyloxyphenyl maleimides and their characterization as thermal‐resistance resins
Authors: Liu Feng , Liu Jinge , Zhao Tong
Published: November 2009

Novel thermosetting monomers possessing both maleimide and propargyl groups were first designed and synthesized. The monomers included N‐(2‐propargyloxyphenyl) maleimide (2‐PPM), N‐(3‐propargyloxyphenyl) maleimide (3‐PPM), and N‐(4‐propargyloxyphenyl) maleimide (4‐PPM), and their structures were confirmed with Fourier transform infrared (FTIR) spectroscopy, 1H‐NMR, and elemental analysis. The cure behaviors of these monomers were characterized with differential scanning calorimetry and FTIR spectroscopy, and the results indicated that the monomers had a broader processing window than normal bismaleimide (BMI) resins. The thermal properties of the cured monomers were characterized with thermogravimetric analysis and dynamic mechanical analysis. The 5% mass loss temperatures of the cured monomers were high (ca. 400°C), and the glass‐transition temperatures of cured 2‐PPM, 3‐PPM, and 4‐PPM were 386, 373, and 387°C, respectively, which were much higher than those of typical commercial blended BMI resins. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation and thermal characterization of films containing liquid crystals in a cellulose acetate substrate for externally regulated applications
Authors: Martínez‐Felipe Alfonso , Ballester‐Sarrias Enrique , Imrie Corrie T. , Ribes‐Greus Amparo
Published: November 2009

Two different series of polymer dispersed liquid crystal (PDLC) films were prepared for their future use as externally controlled electrolytes in direct methanol fuel cells (DMFC). The liquid crystals used in this work were commercial cholesteryl oleyl carbonate (COC) and n‐(4‐methoxybencylidine)‐4‐butylanilyne (MBBA); cellulose acetate (CA) was used as the polymer substrate. All the films were characterized by differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA) to analyze the existence of interactions between the components, the modification of the liquid crystal behavior and the thermal stability of the films. The two series of films exhibited very different behaviors. While the films containing CA and COC maintained most of the properties characteristic of the pure components, including the COC mesomorphism, the analysis of films containing CA and MBBA revealed the existence of strong interactions between the components that promoted the inhibition of the MBBA mesomorphic behavior. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Nanocomposites of poly(vinylidene fluoride) with multiwalled carbon nanotubes
Authors: Huang Wenwen , Edenzon Kyle , Fernandez Luis , Razmpour Shabnam , Woodburn Jenna , Cebe Peggy
Published: November 2009

The preparation and characterization of nanocomposites of poly(vinylidene fluoride), PVDF, with acid treated multiwalled carbon nanotubes (MWCNT) with a wide composition range, from 0.1 to 5.0% MWCNT by weight, is reported. Effect of uniaxial orientation by zone drawing on these nanocomposites is discussed and compared with unoriented compression molded films. Static room temperature two‐dimensional wide angle X‐ray scattering and Fourier transform infrared spectroscopy were used for phase identification. Differential scanning calorimetry, polarizing optical microscopy, dynamic mechanical analysis (DMA), and thermogravimetic analysis (TGA) were used to study the thermal and mechanical properties. Incorporation of MWCNT into PVDF has no obvious effect in forming beta phase crystal in the PVDF/MWCNT bulk films, while zone drawing cause a significant alpha to beta transition in PVDF/MWCNT. Results indicate that MWCNTs act as nucleation agent during crystallization and slightly increase the degree of crystallinity of PVDF/MWCNT bulk films. TGA indicates the thermal stability is improved when MWCNT concentration increases for unoriented PVDF/MWCNT film. The modulus also increases significantly when MWCNT concentration increases. The glass transition temperature measured by the peak position of tanδ from DMA does not change with MWCNT concentration, but a slightly higher glass transition can be obtained by zone drawing. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Chain extension reaction in solid‐state polymerization of recycled PET: The influence of 2,2′‐bis‐2‐oxazoline and pyromellitic anhydride
Authors: Nascimento Christine R. , Azuma Chiaki , Bretas Rosário , Farah Marcelo , Dias Marcos L.
Published: November 2009

Conventional and chain extended‐modified solid‐state polymerization (SSP) of postconsumer poly(ethylene terephthalate) (PET) from beverage bottles was investigated. SSP was carried out at several temperatures, reaction times, and 2,2′‐bis‐2‐oxazoline (OXZ) or pyromellitic anhydride (ANP) concentrations. The OXZ was added by impregnation with chloroform or acetone solution. Higher molecular weights were reached when the reaction was carried out with OXZ, resulting in bimodal distribution. The molecular weights of the flakes reacted at 230°C for 4 h were 85,000, 95,000, and 100,000 for samples impregnated with 0, 0.5, and 1.25 wt % OXZ solution, respectively. In the case of reactions with ANP, branched chains were obtained. The thermal and thermal‐mechanical‐dynamic properties of these high‐molecular‐weight recycled PET were determined. For OXZ‐reacted samples, the reduction of crystallinity was observed as the reaction time was increased, becoming evident the destruction of the crystalline phase. The chain extended samples did not show changes in thermal relaxations or thermal degradation behavior. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Processing and mechanical behavior of carbon black graded rubber compounds
Authors: Ahankari Sandeep S. , Kar Kamal K.
Published: November 2009

Functionally graded rubber compounds (FGRCs) were prepared by construction based method. The matrix used was natural rubber (NR). Amorphous carbon black (N‐330) was used as grading material. The gradation of nanoparticles in a rectangular geometry comprised the variation of particle volume fraction along thickness direction. Its performance was evaluated for structural application through various mechanical and surface properties like tensile strength, modulus, tear strength, elongation at break, hardness, fracture surface by scanning electron microscopy, etc. At the same percentage of nanofiller loading, FGRCs show enhanced properties, i.e., modulus and tear strength (in some grades) compared to uniformly dispersed rubber compounds (UDRCs). Modulus of FGRCs, for a given particular stacking sequence of the layers, increases as much as by 275% compared to UDRCs. The ultimate properties like tensile strength and elongation at break made up for the modulus enhancement that decreases to as minimum as 50 and 80%, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Synthesis of reactive soybean oils for use as a biobased thermoset resins in structural natural fiber composites
Authors: Adekunle Kayode , Åkesson Dan , Skrifvars Mikael
Published: November 2009

Biobased thermosets resins were synthesized by functionalizing the triglycerides of epoxidized soybean oil with methacrylic acid, acetyl anhydride, and methacrylic anhydride. The obtained resins were characterized with FTIR, 1H‐NMR, and 13C‐NMR spectroscopy to confirm the functionalization reactions and the extent of epoxy conversion. The viscosities of the methacrylated soybean oil resins were also measured for the purpose of being used as a matrix in composite applications. The cross‐linking capability was estimated by UV and thermally initiated curing experiments, and by DSC analysis regarding the degree of crosslinking. The modifications were successful because up to 97% conversion of epoxy group were achieved leaving only 2.2% of unreacted epoxy groups, which was confirmed by 1H‐NMR. The 13C‐NMR confirms the ratio of acetate to methacrylate methyl group to be 1 : 1. The viscosities of the methacrylated soybean oil (MSO) and methacrylic anhydride modified soybean oil (MMSO) were 0.2 and 0.48 Pas, respectively, which indicates that they can be used in resin transfer molding process. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Evidence for a Rapid Degenerate Hetero‐Cope‐Type Rearrangement in [Cp*W(S)2S‐CH2‐CHCH2]
Authors: Eweiner Florian , Senda Shunsuke , Bergander Klaus , Mück‐Lichtenfeld Christian , Grimme Stefan , Fröhlich Roland , Aoyama Michiko , Kawaguchi Hiroyuki , Ohki Yasuhiro , Matsumoto Tsuyoshi , Kehr Gerald , Tatsumi Kazuyuki , Erker Gerhard
Published: November 2009

Treatment of the salt [PPh4]+[Cp*W(S)3]− (6) with allyl bromide gave the neutral complex [Cp*W(S)2S‐CH2‐CHCH2] (7). The product 7 was characterized by an X‐ray crystal structure analysis. Complex 7 features dynamic NMR spectra that indicate a rapid allyl automerization process. From the analysis of the temperature‐dependent NMR spectra a Gibbs activation energy of ΔG≠ (278 K)≈13.7±0.1 kcal mol−1 was obtained [ΔH≠≈10.4±0.1 kcal mol−1; ΔS≠≈−11.4 cal mol−1 K−1]. The DFT calculation identified an energetically unfavorable four‐membered transition state of the “forbidden” reaction and a favorable six‐membered transition state of the “Cope‐type” allyl rearrangement process at this transition‐metal complex core.
Poly‐quadratic stability of discrete‐time nonlinear systems in Takagi‐Sugeno's form
Authors: Ding Baocang
Published: November 2009

This paper studies poly‐quadratic stability of nonlinear systems represented by a Takagi‐Sugeno (T‐S) discrete fuzzy model. A system is poly‐quadratically stable when its stability can be verified by a parameter dependent Lyapunov function. There are already some results in this area. This paper, however, presents less conservative results by adopting more slack‐matrix‐variables in the linear matrix inequalities (LMIs). The parallel distributed compensation (PDC) law is utilized in both the analysis and the synthesis problems. The effectiveness of the new results in this paper is validated by a simulation example. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Observers for a class of nonlinear systems with time‐delay
Authors: Zhou Lei , Xiao Xiaoqing , Lu Guoping
Published: November 2009

In this paper, the issue of observer designs for a class of nonlinear continuous‐time systems with time‐delay is addressed, where the nonlinear function is not necessarily Lipschitz. It is shown that both full‐order and reduced‐order observers can be obtained by means of the same linear matrix inequality. A numerical example is presented to show the effectiveness of the proposed approach. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
The effect of behavioral skills training with general‐case training on staff chaining of child vocalizations within natural language paradigm
Authors: Seiverling Laura , Pantelides Maria , Ruiz Henry H. , Sturmey Peter
Published: November 2009

This study used behavioral skills training (BST) and general‐case training (GCT) in which the experimenter simulated child performance to teach three staff to conduct NLP and response chaining to increase three‐link vocal chains in three children with autism. Staff increased their correct NLP performance during post‐training in comparison to baseline. Two of three children emitted more vocal chains following training. This study demonstrated that BST and GCT were effective in training NLP and response chaining. When assessing social validity, both Board Certified Behavior Analysts (BCBAs) and teachers did not indicate an increase in staff members' teaching skills. Future research should develop effective technologies to chain vocal behavior and to teach staff and parents to implement response chaining. Copyright © 2009 John Wiley & Sons, Ltd.
New techniques to detect oxidative stress markers: Mass spectrometry‐based methods to detect isoprostanes as the gold standard for oxidative stress in vivo
Authors: Yin Huiyong
Published: November 2009

Free radical‐induced lipid oxidation under oxidative stress has been implicated in a number of human diseases. Isoprostanes (IsoPs), isomers of prostaglandins, are one of the major classes of oxidation products derived from this oxidation process. Measurement of the levels of IsoPs by Mass Spectrometry‐based methods has become the “gold standard” biomarker of oxidative stress in vivo. Significant advances have been made in understanding this important pathway of lipid peroxidation since the discovery of IsoP formation in vivo 18 years ago. Studies from our laboratory and others are discussed that have provided insights into the mechanism of formation. Furthermore, new independent studies have demonstrated that IsoPs are the most reliable available marker of lipid peroxidation in vivo, and recent work examining IsoP formation has provided valuable information about the pathogenesis of numerous human diseases. Thus, the complexity of the IsoP pathway has expanded, providing novel insights into mechanisms of lipid peroxidation in vivo and allowing investigators to explore the role of oxidative stress in human disease.
Clinical relevance of plasma homocysteine levels in Taiwanese patients with coronary artery disease
Authors: Cheng Mei‐Ling , Ho Hung‐Yao , Lin Jui‐Fen , Chan Err‐Cheng , Chiu Daniel Tsun‐Yee , Chen Yo‐Cheng
Published: November 2009

Homocysteine (Hcy) has recently been considered as a risk factor for cardiovascular disease. Coronary artery disease (CAD) is the third most common cause of mortality in Taiwan. The objective of our present study is to delineate the relationship between the plasma Hcy level and CAD in Taiwanese using an improved enzymatic method. Blood samples were collected from 86 CAD patients, which include 38 patients with acute coronary syndrome (ACS) and 48 patients with stable CAD, and 89 controls. Plasma Hcy levels were measured by HPLC and enzymatic methods. Plasma Hcy levels were 8.27 ± 1.74, 8.50 ± 1.88 and 11.76 ± 4.58 μM in normal controls, patients with stable CAD and those with ACS, respectively. Plasma Hcy levels were elevated in the cohort of ACS patients, as compared with those of normal controls or patients with stable CAD. Within the CAD group, patients with the highest quartile Hcy level (10.18‐23.73 μM) had a significantly higher odd ratio for ACS, as compared with those with the lowest quartile Hcy level after multivariate adjustment. Plasma Hcy concentration can be used as an independent risk factor of ACS, particularly for those with a history of CAD. Moreover, our improved enzymatic assay can be automated for large‐scale screening of high‐risk cohorts.
Functional expression and characterization of human 101F6 protein, a homologue of cytochrome b561 and a candidate tumor suppressor gene product
Authors: Recuenco Mariam C. , Fujito Masamitsu , Sakamoto Yoichi , Tsubaki Motonari , Rahman M. D. Motiur , Takeuchi Fusako
Published: November 2009

A highly hydrophobic protein with six transmembrane structure that is coded by the candidate tumor suppressor gene 101F6 located in the human chromosome 3p.21.3 and a possible member of the cytochrome b 561 protein family was expressed, purified, and characterized in its functional form for the first time. The protein was heterologously expressed in methylotrophic yeast Pichia pastoris as a fusion protein containing a C‐terminal thrombin‐specific sequence and an 8‐His residue tag. Purification was achieved by ion exchange chromatography on DEAE‐Sepharose and affinity chromatography on Ni‐NTA‐Sepharose. SDS‐PAGE analysis revealed a single protein band with an estimated molecular weight of 26 kDa, while Western blot and MALDI‐TOF‐MS analysis confirmed the presence of the cytochrome b561 specific sequence in the protein. The 101F6 protein was found to be reducible by ascorbate efficiently and to have two midpoint potentials at +89.5 and +13.1 mV, slightly lower than the corresponding values of +155 and +62 mV, respectively, of bovine adrenal cytochrome b 561, despite a lower conservation of the putative ascorbate binding site sequence in the 101F6 protein. The “modified motif 1” sequence unique in 101F6 protein may be responsible for other molecular functions, such as protein‐protein interactions, in the endoplasmic membranes.
ECTO‐NOX (ENOX) proteins of the cell surface lack thioredoxin reductase activity
Authors: Bosneaga Elena , Kim Chinpal , Shen Bernard , Watanabe Takahiro , Morré D. James , Morre Dorothy M.
Published: November 2009

This study was to determine if ENOX proteins of the cell surface act as cell surface thioredoxin reductases. To measure formation of thiols a turbimetric insulin assay was used. No turbidity was observed with insulin alone or with insulin plus DTT. However, the combination of insulin + DTT + recombinant his‐tagged ENOX2 (tNOX) did result in increased turbidity. An ENOX1 (CNOX) preparation also resulted in turbidity changes. In contrast, we were unable to demonstrate ENOX2‐dependent insulin reduction by high density SDS‐PAGE. Inclusion of reduced serum albumin as a source of free thiols for the protein disulfide interchange activity catalyzed by ENOX2 failed to result in insulin reduction in the presence of ENOX2. A direct effect of ENOX2 on thioredoxin reduction in the presence of NADPH also was not observed. The DTNB assay for thioredoxin reductase activity also failed to reveal activity. Thus, ENOX proteins appear not to function as thioredoxin reductases at the cell surface nor do they appear to recognize reduced insulin as a substrate for protein disulfide‐thiol interchange. The enhanced turbidity of insulin solutions resulting from ENOX presence was traced to ENOX‐catalyzed insulin fibrillation either through nucleation enhancement or some other mechanism. Fibrillation was determined using Thioflavin T fluorescence which paralleled the turbimetric results and the formation of multimers (polymerization) observed on SDS‐PAGE.
Effects of hydrophobicity and anions on self‐assembly of the peptide EMK16‐II
Authors: Zou Dawei , Tie Zuoxiu , Lu Chunmei , Qin Meng , Lu Xiaomei , Wang Mu , Wang Wei , Chen P.
Published: November 2009

Effects of hydrophobic and electrostatic interactions on the self‐assembling process of the ionic‐complementary peptide EMK16‐II are investigated by atomic force microscopy imaging, circular dichroism spectra, light scattering, and chromatography. It is found that the hydrophobicity of the peptide promotes the aggregation in pure water even at a very low concentration, resulting in a much lower critical aggregation concentration than that of another peptide, EAK16‐II. The effect of anions in solution with different valences on electrostatic interactions is also important. Monovalent anions (Cl− and Ac−) with a proper concentration can facilitate the formation of peptide fibrils, with Cl− of smaller size being more effective than Ac− of larger size. However, only small amounts of fibrils, but plenty of large amorphous aggregates, are found when the peptide solution is incubated with multivalent anions, such as SO, C6H5O, and HPO. More importantly, by gel filtration chromatography, the citrate anion, which induces a similar effect on the self‐assembling process of EMK16‐II as that of SO and HPO, can interact with two or more positively charged residues of the peptide and reside in the amorphous aggregates. This implies a “salt bridge” effect of multivalent anions on the peptide self‐assembling process, which can interpret a previous puzzle why divalent cations inhibit the formation of ordered nanofibrils of the ionic‐complementary peptides. Thus, our results clarify the important effects of hydrophobic and electrostatic interactions on the self‐assembling process of the ionic‐complementary peptides. These are greatly helpful for us to understand the mechanism of peptides' self‐assembling process and protein folding and aggregation. © 2009 Wiley Periodicals, Inc. Biopolymers 93: 318–329, 2010.

This article was originally published online as an acceptedpreprint. The “Published Online” date corresponds to the preprintversion. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Conformational preferences and prolyl cis–trans isomerization of phosphorylated Ser/Thr‐Pro motifs
Authors: Byun Byung Jin , Kang Young Kee
Published: November 2009

The conformational study on Ac‐pSer‐Pro‐NHMe and Ac‐pThr‐Pro‐NHMe peptides has been carried out using hybrid density functional methods with the implicit solvation reaction field theory at the B3LYP/ 6‐311++G(d,p)//B3LYP/6‐31+G(d) level of theory in the gas phase and in solution (chloroform and water). For both pSer‐Pro and pThr‐Pro peptides in the gas phase and in chloroform, the most preferred conformation has the α‐helical structure for the pSer/pThr residue, the down‐puckered polyproline I structure for the Pro residue, and the cis prolyl peptide bond between the two residues, in which two hydrogen bonds between the phosphate oxygens with the backbone NH groups seem to play a role. However, the trans conformations that have a single hydrogen bond of the phosphate oxygen with either of two backbone NH groups become most preferred for both peptides in water. This is because the hydration free energy of the anionic oxygen of the phosphate group is expected to dramatically decrease for the cis conformation upon formation of the hydrogen bond with the backbone NH groups. These calculated results are consistent with the observations by NMR and IR experiments, suggesting the existence of hydrogen bonds between the charged phosphoryl group and the backbone amide protons in solution. The calculated cis populations of 14.7 and 14.2% and rotational barriers of 19.87 and 20.57 kcal/mol to the cis‐to‐trans isomerization for pSer‐Pro and pThr‐Pro peptides in water, respectively, are consistent with the observed values for pSer‐Pro and pThr‐Pro containing peptides from NMR experiments. However, the hydrogen bond between the prolyl nitrogen and the following amide NH group, which was suggested to be capable of catalyzing the prolyl isomerization, does not play a role in stabilizing the preferred transition state for the pSer/pThr‐Pro peptides in water. Instead, the amide hydrogen of the NHMe group is involved in a bifurcated hydrogen bond with the anionic oxygen and phosphoester oxygen of the phosphate group. © 2009 Wiley Periodicals, Inc. Biopolymers 93: 330–339, 2010.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Development and validation of a HPLC method for determination of levonorgestrel and quinestrol in rat plasma
Authors: Tang Tao , Li Pingliang , Luo Laixin , Shi Dazhao , Li Jianqiang , Cao Yongsong
Published: November 2009

Levonorgestrel and quinestrol, commonly known as EP‐1, has long been used in the control of wild rodents. Up to the present time, however, no method for simultaneous quantification of levonorgestrel and quinestrol in rat plasma has been reported. In the present study, a sensitive reverse‐phase high‐performance liquid chromatography with ultraviolet detection (RP‐HPLC‐UV) method for quantification of levonorgestrel and quinestrol in rat plasma has been developed. It uses a Kromasil ODS C18 column and acetonitrile‐0.1% formic acid (85 : 15, v/v) mobile phase at ambient temperature. The plasma sample was prepared by hexane–isoamyl alcohol extraction (90 : 10, v/v). The flow rate and detection wavelength were 1.0 mL/min and 230 nm. The correlation coefficients were greater than 0.9995 within 0.08–50 μg/mL for levonorgestrel and 0.12–50 μg/mL for quinestrol, and the limits of detection were 0.02 and 0.05 μg/mL for levonorgestrel and quinestrol, respectively. Average recovery ranged from 92.5 to 96.3% and inter‐day RSDs were less than 7.56%. This method can be applied to the further pharmacokinetic study of levonorgestrel and quinestrol in rat plasma. Copyright © 2009 John Wiley & Sons, Ltd.
In vitro and in vivo studies of androst‐4‐ene‐3,6,17‐trione in horses by gas chromatography–mass spectrometry
Authors: Leung Gary N. W. , Tang Francis P. W. , Wan Terence S. M. , Wong Colton H. F. , Lam Kenneth K. H. , Stewart Brian D.
Published: November 2009

This paper describes the application of gas chromatography–mass spectrometry (GC‐MS) for in vitro and in vivo studies of 6‐OXO in horses, with a special aim to identify the most appropriate target metabolite to be monitored for controlling the administration of 6‐OXO in racehorses. In vitro studies of 6‐OXO were performed using horse liver microsomes. The major biotransformation observed was reduction of one keto group at the C3 or C6 positions. Three in vitro metabolites, namely 6α‐hydroxyandrost‐4‐ene‐3,17‐dione (M1), 3α‐hydroxyandrost‐4‐ene‐6,17‐dione (M2a) and 3β‐hydroxyandrost‐4‐ene‐6,17‐dione (M2b) were identified. For the in vivo studies, two thoroughbred geldings were each administered orally with 500 mg of androst‐4‐ene‐3,6,17‐trione (5 capsules of 6‐OXO®) by stomach tubing. The results revealed that 6‐OXO was extensively metabolized. The three in vitro metabolites (M1, M2a and M2b) identified earlier were all detected in post‐administration urine samples. In addition, seven other urinary metabolites, derived from a further reduction of either one of the remaining keto groups or one of the remaining keto groups and the olefin group, were identified. These metabolites included 6α,17β‐dihydroxyandrost‐4‐en‐3‐one (M3a), 6,17‐dihydroxyandrost‐4‐en‐3‐one (M3b and M3c), 3β,6β‐dihydroxyandrost‐4‐en‐17‐one (M4a), 3,6‐dihydroxyandrost‐4‐en‐17‐one (M4b), 3,6‐dihydroxyandrostan‐17‐one (M5) and 3,17‐dihydroxyandrostan‐6‐one (M6). The longest detection time observed in urine was up to 46 h for the M6 metabolite. For blood samples, the peak 6‐OXO plasma concentration was observed 1 h post administration. Plasma 6‐OXO decreased rapidly and was not detectable 12 h post administration. Copyright © 2009 John Wiley & Sons, Ltd.
Staying safe: strategies for qualitative child abuse researchers
Authors: Coles Jan , Mudaly Neerosh
Published: November 2009

Undertaking interview‐based research with victim/survivors of child abuse can be difficult and challenging for researchers. Much has been written about the impact of research on participants, but researcher effects are less explored. This paper reviews the literature on sensitive interview‐based research and child abuse research. The theoretical underpinnings of researcher trauma are outlined and challenges identified and related to child abuse research using researcher reflections from the authors' interview‐based research with children who have been abused and young mothers who were sexually abused in childhood. Strategies and recommendations are developed to minimise child abuse researcher trauma. Copyright © 2009 John Wiley & Sons, Ltd.
Effects of supplementation with free glutamine and the dipeptide alanyl‐glutamine on parameters of muscle damage and inflammation in rats submitted to prolonged exercise
Authors: Cruzat Vinicius Fernandes , Rogero Marcelo Macedo , Tirapegui Julio
Published: November 2009

In this study, we investigated the effect of the supplementation with the dipeptide L‐alanyl‐L‐glutamine (DIP) and a solution containing L‐glutamine and L‐alanine on plasma levels markers of muscle damage and levels of pro‐inflammatory cytokines and glutamine metabolism in rats submitted to prolonged exercise. Rats were submitted to sessions of swim training for 6 weeks. Twenty‐one days prior to euthanasia, the animals were supplemented with DIP (n = 8) (1.5 g.kg−1), a solution of free L‐glutamine (1 g.kg−1) and free L‐alanine (0.61 g.kg−1) (G&A, n = 8) or water (control (CON), n = 8). Animals were killed at rest before (R), after prolonged exercise (PE—2 h of exercise). Plasma concentrations of glutamine, glutamate, tumour necrosis factor‐α (TNF‐α), prostaglandin E2 (PGE2) and activity of creatine kinase (CK), lactate dehydrogenase (LDH) and muscle concentrations of glutamine and glutamate were measured. The concentrations of plasma TNF‐α, PGE2 and the activity of CK were lower in the G&A‐R and DIP‐R groups, compared to the CON‐R. Glutamine in plasma (p < 0.04) and soleus muscle (p < 0.001) was higher in the DIP‐R and G&A‐R groups relative to the CON‐R group. G&A‐PE and DIP‐PE groups exhibited lower concentrations of plasma PGE2 (p < 0.05) and TNF‐α (p < 0.05), and higher concentrations of glutamine and glutamate in soleus (p < 0.001) and gastrocnemius muscles (p < 0.05) relative to the CON‐PE group. We concluded that supplementation with free L‐glutamine and the dipeptide LL‐alanyl‐LL‐glutamine represents an effective source of glutamine, which may attenuate inflammation biomarkers after periods of training and plasma levels of CK and the inflammatory response induced by prolonged exercise. Copyright © 2009 John Wiley & Sons, Ltd.
Template‐Synthesized Porous Silicon Carbide as an Effective Host for Zeolite Catalysts
Authors: Gu Lijun , Ma Ding , Yao Songdong , Liu Xiumei , Han Xiuwen , Shen Wenjie , Bao Xinhe
Published: November 2009

A facile method has been developed for the fabrication of porous silicon carbide (SiC) by means of sintering a mixture of SiC powder and carbon pellets at a relatively lower temperature, that is, 1450 °C, in air. The pore density and the total pore volume of the resulting porous SiC could be tuned by changing the initial SiC/C weight ratio. The structure evolution and the associated property changes during the preparation were examined through X‐ray diffraction, scanning electron microscopy, thermogravimetric analysis, 29Si magic‐angle spinning (MAS) NMR spectroscopy, and mercury‐intrusion porosimetry analyses. Silica and SiOxCy ceramics formed in situ during the calcination process acted as binders of the porous SiC grains. The porous SiC can be used as a host for the growth of ZSM‐5 zeolite crystals to form the ZSM‐5/porous‐SiC composite material. After loading another catalytic active component of molybdenum, a novel catalytic material, Mo‐ZSM‐5/porous‐SiC, was obtained, which exhibited improved catalytic activity in the methane dehydroaromatization reaction.
Molecular tweezers for enantiodiscrimination in NMR: Di‐(R,R)‐1‐[10‐(1‐hydroxy‐2,2,2‐trifluoroethyl)‐9‐anthryl]‐2,2,2‐trifluoroethyl benzenedicarboxylates
Authors: Gil Sergio , Palomino‐Schätzlein Martina , Burusco Kepa Koldo , Jaime Carlos , Virgili Albert
Published: November 2009

A series of new chiral molecular tweezers, di‐(R,R)‐1‐[10‐(1‐hydroxy‐2,2,2‐trifluoroethyl)‐9‐anthryl]‐2,2,2‐trifluoroethyl phthalate (2), isophthalate (3) and terephthalate (4), were synthesized and their structure studied by NMR and molecular mechanics. Their effectiveness as chiral solvating agents for the determination of the enantiomeric purity of chiral compounds using NMR was demonstrated. Chirality 2010. © 2009 Wiley‐Liss, Inc.
Experimental and computational studies of enantioseparation of structurally similar chiral compounds on amylose tris(3,5‐dimethylphenylcarbamate)
Authors: Kasat Rahul B. , Franses Elias I. , Wang Nien‐Hwa Linda
Published: November 2009

The enantioseparation of 14 structurally similar chiral solutes, with one or two chiral centers, are studied for a commercially important polysaccharide‐based chiral stationary phase, amylose tris(3,5‐dimethylphenylcarbamate) (ADMPC). Among these solutes, only two solutes show significant enantioresolutions of 2 to 2.5 in n‐hexane/2‐propanol (90/10, v/v) at 298 K. The retention factors of the chiral solutes vary significantly from 0.7 to 7.0, and they are compared with those of simpler nonchiral solutes having similar but fewer functional groups. The sorbent–solute H‐bonding interactions between the solute functional groups and the polymer CO and NH functional groups are probed with attenuated total reflection infrared spectroscopy (ATR‐IR). The H‐bonding interactions of the polymer CO and NH groups with the solutes result in changes in the IR amide band wavenumbers of ADMPC upon solute adsorption. The nanostructure of an ADMPC cavity and the potential interactions with the chiral solutes are proposed based on the sorbent–solute–solvent HPLC data, the sorbent–solute IR data, and the sorbent–solute molecular dynamics (MD) simulations. The results are consistent with the three point attachment hypothesis and indicate that a significant enantioresolution in ADMPC requires at least three different interaction sites for simultaneous H‐bonds and phenyl–phenyl interactions for phenylpropylamine (PPA) and various structurally similar chiral solutes. Chirality 2010. © 2009 Wiley‐Liss, Inc.
Estimation methods for time‐dependent AUC models with survival data
Authors: Hung Hung , Chiang Chin‐Tsang
Published: November 2009

The performance of clinical tests for disease screening is often evaluated using the area under the receiver‐operating characteristic (ROC) curve (AUC). Recent developments have extended the traditional setting to the AUC with binary time‐varying failure status. Without considering covariates, our first theme is to propose a simple and easily computed nonparametric estimator for the time‐dependent AUC. Moreover, we use generalized linear models with time‐varying coefficients to characterize the time‐dependent AUC as a function of covariate values. The corresponding estimation procedures are proposed to estimate the parameter functions of interest. The derived limiting Gaussian processes and the estimated asymptotic variances enable us to construct the approximated confidence regions for the AUCs. The finite sample properties of our proposed estimators and inference procedures are examined through extensive simulations. An analysis of the AIDS Clinical Trials Group (ACTG) 175 data is further presented to show the applicability of the proposed methods. The Canadian Journal of Statistics 38:8–26; 2010 © 2009 Statistical Society of Canada
Die Publikumsfrage in der Chemie‐Vorlesung
Authors: Fels Gregor
Published: November 2009

Wer kennt sie nicht, die Quizsendung „Wer wird Millionär”︁, bei der die Zuschauer im Studio über die Publikumsfrage aktiv am Quiz beteiligt werden? Technisch erfolgt das über ein „personal response system”︁ (PRS), mit dem sich registrieren und anzeigen lässt, wie viel Prozent der Zuschauer jeweils welche der vorgegebenen Antworten für die richtige Lösung hält. Da ist man auch als Zuschauer ganz bei der Sache, und sollte man einmal die Antwort nicht gewusst oder die Frage sogar falsch beantwortet haben, kann man trotzdem noch zufrieden sein, denn man hat ja nichts verloren, sondern im Gegenteil noch etwas dazu gelernt. So wie die Zuschauer über die Publikumsfrage in das Quiz einbezogen werden, können Dozenten die Studierenden mit Hilfe von PRS‐Verfahren aus ihrer traditionell passiven Rolle herausholen und aktiv an der Vorlesung beteiligen.
Rare incidence of congestive heart failure in gastrointestinal stromal tumor and other sarcoma patients receiving imatinib mesylate
Authors: Trent Jonathan C. , Patel Shalin S. , Zhang Jianhu , Araujo Dejka M. , Plana Juan‐Carlos , Lenihan Daniel J. , Fan Dominic , Patel Shreyaskumar R. , Benjamin Robert S. , Khakoo Aarif Y.
Published: November 2009

BACKGROUND:

The authors sought to determine the incidence and severity of cardiovascular toxicity caused by imatinib mesylate in gastrointestinal stromal tumor (GIST) and other sarcoma patients, and to explore cardiotoxicity caused by imatinib mesylate using cell culture and in vitro models.

METHODS:

To determine the incidence and significance of serious cardiac adverse events in GIST and other sarcoma patients receiving imatinib mesylate, the authors performed a retrospective analysis of 219 consecutive patients treated with imatinib mesylate. In vitro studies of imatinib mesylate on cultured cardiomyocytes and biochemical studies of cardiac lysates from mice treated with imatinib mesylate were performed to define the potential cardiotoxic effects of imatinib mesylate.

RESULTS:

Grade 3 or 4 potentially cardiotoxic adverse events (mostly edema or effusions) occurred in 8.2% of patients, were manageable with medical therapy, and infrequently required dose reduction or discontinuation of imatinib mesylate. Arrhythmias, acute coronary syndromes, or heart failure were uncommon, occurring in <1% of treated patients. However, administration of imatinib in a mouse model system resulted in inhibition of activation of protein kinases that are known to be important in the cardiac stress response.

CONCLUSIONS:

The authors concluded that imatinib is an uncommon cause of cardiotoxicity, and that the cardiovascular adverse events that occur are manageable when recognized and treated. Nevertheless, our preclinical findings suggest that imatinib remains a potential cardiotoxin. Furthermore, the cardiac consequences of long‐term imatinib therapy remain unknown. We therefore recommend treatment of risk factors for cardiovascular disease in imatinib‐treated patients in accord with the American Heart Association guidelines for the prevention and treatment of heart failure. Cancer 2010. © 2010 American Cancer Society.
Cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations and risk for pancreatic adenocarcinoma
Authors: McWilliams Robert R. , Petersen Gloria M. , Rabe Kari G. , Holtegaard Leonard M. , Lynch Pamela J. , Bishop Michele D. , Highsmith W. Edward
Published: November 2009

BACKGROUND:

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene are common in white persons and are associated with pancreatic disease. The purpose of this case‐control study was to determine whether CFTR mutations confer a higher risk of pancreatic cancer.

METHODS:

In a case‐control study, the authors compared the rates of 39 common cystic fibrosis‐associated CFTR mutations between 949 white patients with pancreatic adenocarcinoma and 13,340 white controls from a clinical laboratory database for prenatal testing for CFTR mutations. The main outcome measure was the CFTR mutation frequency in patients and controls.

RESULTS:

Overall, 50 (5.3%) of 949 patients with pancreatic cancer carried a common CFTR mutation versus 510 (3.8%) of 13,340 controls (odds ratio [OR], 1.40; 95% confidence interval [CI], 1.04‐1.89; P = .027). Among patients who were younger when their disease was diagnosed (<60 years), the carrier frequency was higher than in controls (OR, 1.82; 95% CI, 1.14‐2.94; P = .011). In patient‐only analyses, the presence of a mutation was associated with younger age (median 62 vs 67 years; P = .034). In subgroups, the difference was seen only among ever‐smokers (60 vs 65 years, P = .028). Subsequent sequencing analysis of the CFTR gene detected 8 (16%) compound heterozygotes among the 50 patients initially detected to have 1 mutation.

CONCLUSIONS:

Carrying a disease‐associated mutation in CFTR is associated with a modest increase in risk for pancreatic cancer. Those affected appear to be diagnosed at a younger age, especially among smokers. Clinical evidence of antecedent pancreatitis was uncommon among both carriers and noncarriers of CFTR mutations. Cancer 2010. © 2010 American Cancer Society.
One‐Step Hydrothermal Synthesis of Nitrogen‐Doped Nanocarbons: Albumine Directing the Carbonization of Glucose
Authors: Baccile Niki , Antonietti Markus , Titirici Maria‐Magdalena
Published: November 2009

We present a simple and green one‐step pathway towards nitrogen‐doped carbon nanostructures with controlled mesoporosity through hydrothermal treatment of glucose in the presence of model proteins. Performing the reaction with different amounts of egg white ovalbumin protein (OvA), carbonaceous nanoparticles or continuous nanosponges with high specific surface areas can be efficiently produced. The nitrogen content of the structures is rather high (up to 8 wt %) and can be kept constant up to 950 °C, while oxygen elimination and graphitization of the carbon material occurs. We demonstrate here that sustainable natural resources can be efficiently used in the synthesis of pure high‐potential nanomaterials.