bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the migration in PA6‐OMMT nanocomposites: effect of annealing on migration as evidenced by ARXPS (angle resolved X‐ray photoelectron spectroscopy)
Authors: Huang Nianhua , Lewin Menachem , Tang Yong , Fan Chou , Wang Jianqi 
Published: April 2008

AbstractThe present paper deals with experiments in which the angle resolved X‐ray photoelectron spectroscopy (ARXPS) technique was applied to investigate the phenomenon of migration in polyamide 6 with organically modified montmorillonite (PA6‐OMMT) nanocomposites. This is the first time ARXPS was used, to gain a more detailed insight into the migration process. Curve‐fitting analyses are reported which enable the differentiation between a manual mixture of PA6 with OMMT at room temperature from a nanocomposite structure. The ARXPS technique was applied to annealed samples at 250, 275, and 285°C, for 2 hr, and with three take of angles, α, of 90, 60, and 30°. The depth of the layer investigated is 9 nm in case the sample surface is well defined. By tilting the take‐off angle of the beam‐out electrons one can determine the intensity of the signals at various distances from the surface within the investigated layer. The concentration gradient of the Si signals is observed. The rate of migration is found to be more rapid in the layer closest to the surface. The intensity of the Si signals in the investigated layer is found to be 1.8 to 9.1 times that of the same composite sample at room temperature. This ratio determines the extent of migration. At temperatures higher than 250°C and times of annealing greater than 30 min a decrease in the extent of migration is observed. This decrease is explained by the gradual decomposition of the surfactant and the consequent removal of the polymeric matrix molecules from the migrating exfoliated units, culminating in denuded alumino‐silicate layers. These layers aggregate to noncolloidal microcomposite particles which do not migrate. The concentration of the exfoliated units decreases with consequent decrease in migration. A gradient of decreasing concentration of Si2p signals was observed after various times of annealing, where the gradient becomes more uniform with increase in time. Copyright © 2008 John Wiley & Sons, Ltd.
Potassium diperiodatonickelate‐initiated graft copolymerization of methyl acrylate onto organophilic montmorillonite
Authors: Deng Kuilin , Liu Jing , Zheng Xiangyang , Zhang Yaqin , Jia Na , Tian Hua , Liu Yinghai 
Published: April 2008

AbstractUsing potassium diperiodatonickelate (Ni (IV)) as an efficient initiator, the graft copolymerization of methyl acrylate (MA) onto organophilic montmorillonite (OMMT) was successfully performed in an alkaline medium. Three grafting parameters were systematically evaluated as functions of the temperature, the initiator concentration, reaction time, pH value, and the ratio of MA to OMMT substrate. The structure of the titled graft copolymers (OMMT‐g‐PMA) were confirmed by Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and thermo‐gravimetric analysis (TGA). It was found that Ni (IV) was a highly efficient initiator for graft copolymerization of the MA onto OMMT, i.e., grafting efficiency is as high as 95% and grafting percentage can be facilely controlled within 700% in this study. In addition, the highest grafting efficiency and grafting percentage were obtained when temperature adopted was over 40°C and pH was about 10.3. A single‐electron‐transfer mechanism was proposed to illustrate the formation of radicals and the initiation reaction. Copyright © 2008 John Wiley & Sons, Ltd.
Color tunability in non‐doped single‐layer PLEDs from a carbazole‐based electroluminescent polymer
Authors: Liu Yingliang , Cao Huayu , Xin Yuanrong , Li Jianghui , Chen Zhijian , Gong Qihuang , Cao Shaokui 
Published: April 2008

AbstractA conjugated polymer with a carbazole moiety, poly(3,6‐divinylene‐N‐octyl‐carbazole‐p‐phenylene), was synthesized by Wittig reaction. The polymer can be dissolved in common organic solvents such as THF, chloroform, etc. Using this polymer as an active layer, single‐layer non‐doped PLEDs with different thicknesses were fabricated by a spin‐coating approach. The results suggested that electroluminescence spectra are changed with the film thickness of the polymer emitter. Fortunately, CIE 1931 coordinate values are moved to the white‐light region only by changing the film thickness. Copyright © 2008 John Wiley & Sons, Ltd.
Microencapsulated ammonium polyphosphate with urea–melamine–formaldehyde shell: preparation, characterization, and its flame retardance in polypropylene
Authors: Wu Kun , Wang Zhengzhou , Hu Yuan 
Published: April 2008

AbstractMicroencapsulated ammonium polyphosphate (MCU‐APP) with urea–melamine–formaldehyde (UMF) resin is prepared by in situ polymerization, and is characterized by FTIR and XPS. The microencapsulation of APP with the UMF resin leads to a decrease in the particle's water solubility. The flame retardant actions of MCU‐APP and APP in PP are studied using limiting oxygen index (LOI) and UL‐94 test, and their thermal stability is evaluated by thermogravimetric analysis. It is found that the LOI value of the PP/MCU‐APP composite is higher than the value of the PP/APP composite. In comparison with the PP/MCU‐APP composites, the LOI values of the PP/MCU‐APP/DPER ternary composites at the same additive loading increase, and UL‐94 ratings of most ternary composites are raised to V‐0. The water‐resistant properties of the PP composites containing APP and MCU‐APP are studied. Moreover, the combustion behavior of the PP composites is investigated by the cone calorimeter. Copyright © 2008 John Wiley & Sons, Ltd.
The proteome of gastric lymph in normal and nematode infected sheep
Authors: Goldfinch Gillian M. , Smith W. David , Imrie Lisa , McLean Kevin , Inglis Neil F. , Pemberton Alan D. 
Published: April 2008

AbstractLymph node cannulation allows the collection of lymph draining from a defined anatomical region. Proteomic analysis of that lymph offers a potentially valuable insight into the immunoinflammatory response of that particular region. In this study, ovine gastric lymph has been used to monitor the proteomic changes occurring in the tissue fluid of the abomasum, in response to infection with the parasitic nematode, Teladorsagia circumcincta. Lymph, collected temporally over an experimental infection period, was analysed by means of 2‐DE and subsequent gel analysis using densitometry software. In addition, the composition of the lymphatic proteome was further explored by means of MALDI‐TOF and MS/MS analyses. The concentration of gelsolin, α‐1 β glycoprotein and haemopexin were altered significantly (p<0.05) with infection.
Predicting left ventricular remodeling after a first myocardial infarction by plasma proteome analysis
Authors: Pinet Florence , Beseme Olivia , Cieniewski‐Bernard Caroline , Drobecq Hervé , Jourdain Sabine , Lamblin Nicolas , Amouyel Philippe , Bauters Christophe 
Published: April 2008

AbstractRecent improvements in therapeutic strategies did not prevent left ventricular remodeling (LVR), which remains a common event (30%) after acute myocardial infarction (AMI). We report the use of a systematic approach, based on comparative proteomics, to select circulating biomarkers that may be associated with LVR. We selected 93 patients enrolled in a prospective study. These patients with anterior wall Q‐wave AMI underwent echocardiographic follow‐up at hospitalization, 3 months and 1 year after AMI. They were divided into three groups (no, low, or high remodeling). Plasma samples of these patients (day 5 of hospitalization) were processed and stored at −80°C within 2 h and analyzed using SELDI‐TOF protein chip technology. This systematic approach allowed to select candidate proteins modulated by LVR: post‐translational variants of α1‐chain of haptoglobin (Hpα1) corresponding to m/z 9493, 9565, and 9623, which were more elevated in remodeling patients. The peak 9493 m/z was shown having a receiving‐operating characteristic (ROC) value of 0.71 between non‐ and remodeling patients. SELDI‐TOF approach may lead to the identification of circulating proteins associated with LVR. Whether these candidate proteins will help to identify patients who are at high risk of heart failure after AMI will have to be tested in future studies.
Enhanced nuclear proteomics
Authors: Barthéléry Miguel , Salli Ugur , Vrana Kent E. 
Published: April 2008

AbstractNuclear proteomics provides an opportunity to examine protein effectors that contribute to cellular phenotype. Both the quality and sensitivity of gel‐based nuclear proteomics are limited, however, by the over‐representation of histones in the protein mixture. These highly charged proteins overshadow rare species and interfere with IEF. A nuclear isolation and protein extraction procedure, tested on human embryonic stem cells, is reported that effectively isolates intact nuclei and then depletes the sample of histones by taking advantage of their ability to form an insoluble complex with DNA at lower pH (even under denaturing conditions). Ubiquitous histones and abundant nuclear actin, are depleted up to 99 ± 0.02 and 42 ± 5%, respectively. This technique greatly improves electrofocusing efficacy and nearly doubles the number of detected protein spots. This approach to nuclear protein isolation for 2‐D PAGE opens the door to better investigation of nuclear protein dynamics.
Investigating copper‐regulated protein expression in Menkes fibroblasts using antibody microarrays
Authors: Du Tai , La Fontaine Sharon L. , Abdo Michael , Bellingham Shayne A. , Greenough Mark , Volitakis Irene , Cherny Robert A. , Bush Ashley I. , Hudson Peter J. , Camakaris James , Mercer Julian F. , Crouch Peter J. , Masters Colin L. , Perreau Victoria M. , White Anthony R. 
Published: April 2008

AbstractNeurodegenerative illnesses are characterized by aberrant metabolism of biometals such as copper (Cu), zinc (Zn) and iron (Fe). However, little is known about the metabolic effects associated with altered metal homeostasis. In this study, we used an in vitro model of altered Cu homeostasis to investigate how Cu regulates cellular protein expression. Human fibroblasts containing a natural deletion mutation of the Menkes (MNK) ATP7A Cu transporter (MNK deleted) were compared to fibroblasts overexpressing ATP7A (MNK transfected). Cultures of MNK‐transfected (Low‐Cu) cells exhibited 95% less intracellular Cu than MNK‐deleted (High‐Cu) cells. Comparative proteomic analysis of the two cell‐lines was performed using antibody microarrays, and significant differential protein expression was observed between Low‐Cu and High‐Cu cell‐lines. Western blot analysis confirmed the altered protein expression of Ku80, nexilin, L‐caldesmon, MAP4, Inhibitor 2 and DNA topoisomerase I. The top 50 altered proteins were analysed using the software program Pathway Studio (Ariadne Genomics) and revealed a significant over‐representation of proteins involved in DNA repair and maintenance. Further analysis confirmed that expression of the DNA repair protein Ku80 was dependent on cellular Cu homeostasis and that Low‐Cu levels in fibroblasts resulted in elevated susceptibility to DNA oxidation.
A simple and inexpensive on‐column frit fabrication method for fused‐silica capillaries for increased capacity and versatility in LC‐MS/MS applications
Authors: Wang Ling‐Chi , Okitsu Cindy Yen , Kochounian Harold , Rodriguez Anthony , Hsieh Chih‐Lin , Zandi Ebrahim 
Published: April 2008

AbstractA modified sol–gel method for a one‐step on‐column frit preparation for fused‐silica capillaries and its utility for peptide separation in LC‐MS/MS is described. This method is inexpensive, reproducible, and does not require specialized equipments. Because the frit fabrication process does not damage polyimide coating, the frit‐fabricated column can be tightly connected on‐line for high pressure LC. These columns can replace any capillary liquid transfer tubing without any specialized connections up‐stream of a spray tip column. Therefore multiple columns with different phases can be connected in series for one‐ or multiple‐dimensional chromatography.
Applications in Brain Proteomics: 8th HUPO Brain Proteome Project Workshop 7 October 2007, Seoul, Korea
Authors: Hamacher Michael , Stephan Christian , Hardt Tanja , Eisenacher Martin , Henkel Andreas , Wiltfang Jens , Jimenez Connie R. , Park Young Mok , Marcus Katrin , Meyer Helmut E. 
Published: April 2008

AbstractWhat are the current approaches in brain proteomics? Can we combine different, but complementary study designs to obtain better results concerning brain diseases? What are the neuro‐hotspots, especially in Korea? These were some of the questions the participants of the 8th HUPO Brain Proteome Project Workshop tried to answer prior to the 6th HUPO World Congress in Seoul, Korea. Around 100 scientists came together during the afternoon of 7 October, 2007, to discuss and to catch up on the latest results and strategies concerning Huntington's disease, glioblastoma and standardization.
Clinical assessment of the cancer diagnostic value of prostatic zinc: A comprehensive needle‐biopsy study
Authors: Cortesi M. , Fridman E. , Volkov A. , Shilstein S. Sh. , Chechik R. , Breskin A. , Vartsky D. , Kleinman N. , Kogan G. , Moriel E. , Gladysh V. , Huszar M. , Ramon J. , Raviv G. 
Published: April 2008

AbstractBackgroundThe correlation between Zinc concentration in the prostate's peripheral zone to the onset or presence of malignant process needs to be evaluated in detail.MethodsZinc concentration was measured in ∼1–4 mm3 segments of fresh needle‐biopsy cores, with X‐ray fluorescence, and correlated with the histological findings of these tissue segments.ResultsLocal Zinc concentration is correlated with the presence of cancer (PCa); the higher the Gleason score the greater the Local Zinc depletion. The Zinc value averaged over the entire extracted tissue is specific only to Gleason score 8–9 PCa. The results refer to patients avoiding Zinc‐rich supplements since those show elevated prostatic Zinc concentration in identified cancer tissue. A computer simulation analysis of randomly located 0.03–3.3 cm3 lesions, with particular Gleason score and the measured Local Zinc concentration, revealed a potential diagnostic approach definitely superior to PSA, with sensitivity to the tumor grade and with excellent detection capability for Gleason score >6. Further clinical studies have been designed, both on full prostates after radical prostatectomy as well as on biopsy cores at higher resolution, to establish the accuracy of the method for Gleason score = 6.ConclusionsThe PCa diagnostic potential of Local Zinc concentration is confirmed and there is indication that the amount of Zinc depletion could be used as a measure of the Gleason score of the tumor. Local Zinc concentration mapping has the potential to improve patient selection for biopsy, biopsy site selection and local therapy (e.g., Cryotherapy, Brachytherapy) site selection. Prostate 68:994–1006, 2008. © 2008 Wiley‐Liss, Inc.
Functional annotation by sequence‐weighted structure alignments: Statistical analysis and case studies from the Protein 3000 structural genomics project in Japan
Authors: Standley Daron M. , Toh Hiroyuki , Nakamura Haruki 
Published: April 2008

AbstractA method to functionally annotate structural genomics targets, based on a novel structural alignment scoring function, is proposed. In the proposed score, position‐specific scoring matrices are used to weight structurally aligned residue pairs to highlight evolutionarily conserved motifs. The functional form of the score is first optimized for discriminating domains belonging to the same Pfam family from domains belonging to different families but the same CATH or SCOP superfamily. In the optimization stage, we consider four standard weighting functions as well as our own, the “maximum substitution probability,” and combinations of these functions. The optimized score achieves an area of 0.87 under the receiver‐operating characteristic curve with respect to identifying Pfam families within a sequence‐unique benchmark set of domain pairs. Confidence measures are then derived from the benchmark distribution of true‐positive scores. The alignment method is next applied to the task of functionally annotating 230 query proteins released to the public as part of the Protein 3000 structural genomics project in Japan. Of these queries, 78 were found to align to templates with the same Pfam family as the query or had sequence identities ≥30%. Another 49 queries were found to match more distantly related templates. Within this group, the template predicted by our method to be the closest functional relative was often not the most structurally similar. Several nontrivial cases are discussed in detail. Finally, 103 queries matched templates at the fold level, but not the family or superfamily level, and remain functionally uncharacterized. Proteins 2008. © 2008 Wiley‐Liss, Inc.
Refinement of noncalorimetric determination of the change in heat capacity, ΔCp, of protein unfolding and validation across a wide temperature range
Authors: Talla‐Singh Deepika , Stites Wesley E. 
Published: April 2008

AbstractThe change in heat capacity, ΔCp, on protein unfolding has been usually determined by calorimetry. A noncalorimetric method which employs the Gibbs‐Helmholtz relationship to determine ΔCp has seen some use. Generally, in this method the free energy change on unfolding of the protein is determined at a variety of temperatures and the temperature at which ΔG is zero, Tm, and change in enthalpy at Tm are determined by thermal denaturation and ΔCp is then calculated using the Gibbs‐Helmholtz equation. We show here that an abbreviated method with stability determinations at just two temperatures gives values of ΔCp consistent with values from free energy change on unfolding determination at a much wider range of temperatures. Further, even the free energy change on unfolding from a single solvent denaturation at the proper temperature, when coupled with the melting temperature, Tm, and the van't Hoff enthalpy, ΔHvH, from a thermal denaturation, gives a reasonable estimate of ΔCp, albeit with greater uncertainty than solvent denaturations at two temperatures. We also find that nonlinear regression of the Gibbs‐Helmholtz equation as a function of stability and temperature while simultaneously fitting ΔCp, Tm, and ΔHvH gives values for the last two parameters that are in excellent agreement with experimental values. Proteins 2008. © 2008 Wiley‐Liss, Inc.
The complex structure of calmodulin bound to a calcineurin peptide
Authors: Ye Qilu , Wang Hailong , Zheng Jimin , Wei Qun , Jia Zongchao 
Published: April 2008

AbstractThe activity of the protein phosphatase calcineurin (CN) is regulated by an autoinhibition mechanism wherein several domains from its catalytic A subunit, including the calmodulin binding domain (CaMBD), block access to its active site. Upon binding of Ca2+ and calmodulin (Ca2+/CaM) to CaMBD, the autoinhibitory domains dissociate from the catalytic groove, thus activating the enzyme. To date, the structure of the CN/CaM/Ca2+ complex has not been determined in its entirety. Previously, we determined the structure of a fusion protein consisting of CaM and a 25‐residue peptide taken from the CaMBD, joined by a 5‐glycine linker. This structure revealed a novel CaM binding motif. However, the presence of the extraneous glycine linker cast doubt on the authenticity of this structure as an accurate representation of CN/CaM binding in vivo. Thus, here, we have determined the crystal structure of CaM complexed with the 25‐residue CaMBD peptide without the glycine linker at a resolution of 2.1 Å. The structure is essentially identical to the fusion construction which displays CaM bound to the CaMBD peptide as a dimer with an open, elongated conformation. The N‐lobe from one molecule and C‐lobe from another encompass and bind the CaMBD peptide. Thus, it validates the existence of this novel CaM binding motif. Our experiments suggest that the dimeric CaM/CaMBD complex exists in solution, which is unambiguously validated using a carefully‐designed CaM‐sepharose pull‐down experiment. We discuss structural features that produce this novel binding motif, including the role of the CaMBD peptide residues Arg‐408, Val‐409, and Phe‐410, which work to provide rigidity to the otherwise flexible central CaM helix joining the N‐ and C‐lobes, ultimately keeping these lobes apart and forcing “head‐to‐tail” dimerization to attain the requisite N‐ and C‐lobe pairing for CaMBD binding. Proteins 2008. © 2008 Wiley‐Liss, Inc.
Structure determination of discoidin II from Dictyostelium discoideum and carbohydrate binding properties of the lectin domain
Authors: Aragão Karoline Saboia , Satre Michel , Imberty Anne , Varrot Annabelle 
Published: April 2008

AbstractThe social amoeba Dictyostelium discoideum adopts a cohesive stage upon starvation and then produces Discoidin I and II, two proteins able to bind galactose and N‐acetyl‐galactosamine. The N‐terminal domain or discoidin domain (DS) is widely distributed in eukaryotes where it plays a role in extracellular matrix binding while the C‐terminal domain displays sequence similarities to invertebrate lectins. We present the first X‐ray structures of the wild‐type and recombinant Discoidin II in unliganded state and in complex with monosaccharides. The protein forms a homotrimer which presents two binding surfaces situated on the opposite boundaries of the structure. The binding sites of the N‐terminal domain contain PEG molecules that could mimics binding of natural ligand. The C‐terminal lectin domain interactions with N‐acetyl‐D‐galactosamine and methyl‐β‐galactoside are described. The carbohydrate binding sites are located at the interface between monomers. Specificity for galacto configuration can be rationalized since the axial O4 hydroxyl group is involved in several hydrogen bonds with protein side chains. Titration microcalorimetry allowed characterization of affinity and demonstrated the enthalpy‐driven character of the interaction. Those results highlight the structural differentiation of the DS domain involved in many cell‐adhesion processes from the lectin activity of Dictyostelium discoidins. Proteins 2008. © 2008 Wiley‐Liss, Inc.