bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of poly(methyl methacrylate) nanoparticles prepared by nanoprecipitation using analytical ultracentrifugation, dynamic light scattering, and scanning electron microscopy
Authors: Perevyazko Igor , Vollrath Antje , Hornig Stephanie , Pavlov Georges M. , Schubert Ulrich S. 
Published: August 2010

AbstractNanoprecipitation represents an effective method for the production of polymeric nanoparticles. This technique was used to prepare nanoparticles from solutions of poly(methyl methacrylate) and its copolymers. Since the regulation of main parameters like particle size, particle size distribution, and molar particle mass is very important for future applications, the stable nanoparticle dispersions were examined by scanning electron microscopy, velocity sedimentation, and dynamic light scattering, whereby advantages and disadvantages of each characterization techniques are discussed. Polydispersities of particle size distributions are determined by the ratio of dw/dn, where dw and dn are weight‐ and number‐average diameters, respectively. The particle characteristics strongly depend on the chemical structure of the polymers and the way of preparation and, therefore, vary in the studied cases in the range of 6 < dw < 680 nm, whereas the polydispersity index dw/dn changes in the range of 1.02 to 1.40. It is shown that nanoparticles in a desirable size range can be prepared by solvent–nonsolvent methods (dialysis technique or dropping technique). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3924–3931, 2010
Synthesis of polyoxazolines using glycerol carbonate derivative and end chains functionalization via carbonate and isocyanate routes
Authors: Giardi Chloe , Lapinte Vincent , Nielloud Françoise , Devoisselle Jean‐Marie , Robin Jean‐Jacques 
Published: August 2010

AbstractWe report the cationic ring‐opening polymerization of 2‐methyl‐2‐oxazoline (MOx) using bio‐based initiator (GCTs). The functional initiator GCTs was prepared by tosylation of the corresponding alcohol: glycerol carbonate (GC). The termination stage of the polymerization was achieved in presence of KOH and the telechelic polyoxazoline carrying five‐membered cyclic carbonate and oxazolium end groups (GC‐POxium) was converted to ((HO)2‐POx‐OH) carrying α‐diol and ω‐hydroxyl groups. End‐functionalized polyoxazolines (HO)2‐POx‐OH with Mn ranging from 4200 to 8400 g mol−1 were synthesized. According to GPC results, the polymerizations of MOx using GCTs and other initiator coming from 1,2‐isopropylidene‐glycerol (Solk‐Ts) were compared. On the basis of FTIR and NMR spectroscopies, the chemical modification of end chains of polyoxazolines was investigated by two alternative synthetic routes. The isocyanate route is a postpolymerization urethanization. The nucleophilic reactivity of the α‐diol and ω‐hydroxyl groups of (HO)2‐POx‐OH was studied with functional isocyanate (TESPI). In the carbonate route, the electrophilic reactivity of α‐ and ω‐end groups of GC‐POxium were explored with amine. It was demonstrated that during the termination stage of the polymerization in presence of allylamine both urethane linker in α‐end chain was synthesized and the ω‐oxazolium group was converted into terminal amine. The carbonate route is an alternative to synthesize urethane without isocyanate. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4027–4035, 2010
Kinetics of bulk azide/alkyne “click” polymerization
Authors: Sheng Xia , Mauldin Timothy C. , Kessler Michael R. 
Published: August 2010

AbstractA bulk step‐growth polymerization of multifunctional azides and alkynes through the copper (I)‐catalyzed azide‐alkyne cycloaddition (CuAAC) reaction is described. The polymerization kinetics of two systems containing different diynes, bisphenol E diyne (BE‐diyne)/bisphenol A bisazide (BA‐bisazide) and tetraethylene glycol diyne (TeEG‐diyne)/BA‐bisazide, are evaluated by differential scanning calorimetry (DSC), shear rheology, and thermogravimetric analysis. The effects of catalyst concentration on reaction kinetics are investigated in detail, as are the thermal properties (glass transition and decomposition temperatures) of the formed polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4093–4102, 2010
Single‐molecule imaging of photodegradation reaction in a chiral helical π‐conjugated polymer chain
Authors: Shinohara Ken‐ichi , Kodera Noriyuki , Oohashi Takashi 
Published: August 2010

AbstractHow does the chemical reaction of a single polymer chain progress? This question is not proven, as long as it is studied the data of the ensemble average from the large number of molecules. In this study, we succeeded for the first time in the direct measurement of when, where, and how the chemical reaction of a polymer chain proceeds on a nanometer scale. That is, single‐molecule imaging of the photodegradation reaction of a chiral helical π‐conjugated polymer following laser irradiation of 405 nm was conducted. Analysis of the chemical kinetics showed that the photodegradation of the single polymer chain proceeded stepwise as a quantum phenomenon. When the motility of the chain‐end increased, reactivity of the photodegradation increased. It was also discovered that the photodegradation of the polymer chain proceeded continuously in one direction, like the “domino effect.” Our method allowed dynamic imaging of single polymer chains at a solid/liquid interface, and hence can be applied to the study of many types of polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4103–4107, 2010
Mesophase structure of low‐wetting liquid crystalline polyacrylates with new perfluoroalkyl benzoate side groups
Authors: Martinelli Elisa , Paoli Francesca , Gallot Bernard , Galli Giancarlo 
Published: August 2010

AbstractThe synthesis, thermal behavior, bulk microstructure, and wettability of new polyacrylates carrying spaced 4‐perfluorohexylpropyl benzoate and 4‐perfluorooctylpropyl benzoate units in the side groups were investigated. X‐ray diffraction analysis proved the formation of different smectic mesophases (SmI2, SmF2, and SmC2) and the evolution of their structures and lattice parameters with temperature. The mesophase polymorphic behavior depended on the length of the perfluorinated chain segment in the repeat unit. The electron density profiles along the smectic layer normal were drawn and provided a deeper insight into the packing of the side chains in a tilted, double layer structure. Thin polymer films were cast from solution, and their low wettability was established by measurements of contact angles with different probing liquids. We suggest that the hydrophobicity and lipophobicity of the films are enhanced by the mesophase surface structure which is mediated by the high‐order, mesophase bulk structure. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4128–4139, 2010
Effect of poly(ethylene oxide) on the structure and properties of poly(vinyl alcohol)
Authors: Li Li , Chen Ning , Wang Qi 
Published: August 2010

AbstractTo improve the drawability of poly(vinyl alcohol) (PVA) thermal products, poly(ethylene oxide) (PEO), a special resin with good flexibility, excellent lubricity, and compatibility with many resins, was applied, and the Fourier transform infrared spectroscopy, dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and wide‐angle X‐ray diffraction (WXRD) were adopted to study the hydrogen bonds, water states, thermal properties, crystal structure, and nonisothermal crystallization of modified PVA. It was found that PEO formed strong hydrogen bonds with water and PVA, thus weakened the intra‐ and inter‐hydrogen bonds of PVA, changed the aggregation states of PVA chains, and decreased its melting point and crystallinity. Moreover, the interactions among PVA, water, and PEO retarded the water evaporation and made more water remain in the system to plasticize PVA. The existence of PEO also slowed down the melt crystallization process of PVA, however, increased the nucleation points of system, thus made more and smaller spherulites formed. The weakened crystallization capability of PVA and the lubrication of PEO made PVA chains to have more mobility under the outside force and obtain high mechanical properties. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1946–1954, 2010
Toughening of polycarbonate by core‐shell latex particles: Influence of particle size and spatial distribution on brittle‐ductile transition
Authors: Xu Huijun , Tang Songchao , Yang Long , Hou Wenting 
Published: August 2010

AbstractThe impact toughness of polycarbonate modified with acrylic core‐shell latex particles was investigated. Addition of impact modifiers with size ranging from 115.7 to 231.4 nm can result in maximum impact strength. Equations for spatial distribution of modified particles were proposed to associate the interparticle distance with particle size and modifier volume fraction in terms of two possible morphologies, given by T = d[0.91/(φ)1/3 − 1] or T = d[0.88/(φ)1/3 − 1]. The influence of particle size on brittle‐ductile transition was also studied. The results indicated that critical interparticle distance was not a definitive value and had a narrow region. Moreover, there existed a linear relationship between critical interparticle distance and modifier size, that is, critical interparticle distance would enlarge with the increasing of core‐shell particle size. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1970–1977, 2010
Swelling behavior of chemically crosslinked PVA gels in mixed solvents
Authors: Kudo Shuhei , Otsuka Emiko , Suzuki Atsushi 
Published: August 2010

AbstractWe report the swelling behavior of chemically crosslinked polyvinyl alcohol (PVA) gels with different degrees of hydrolysis in water, several organic solvents, and their mixed solvents. The gels were dried after gelation and were put into their respective solvents. The gel volume in pure water decreased with increasing temperatures, and the total changes increased with decreasing degrees of hydrolysis. The swelling ratio depends on the solvent and its concentration. In the cases of mixed solvents of methanol–water, ethanol–water, and acetone–water, the gels shrank continuously with increasing concentrations of solvents and reached the collapsed state in the pure organic solvent. In the case of dimethyl sulfoxide (DMSO), on the other hand, the gels shrunk, swelled, and finally reached the swollen state in pure DMSO. Results of measurements using Fourier Transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD) suggested that crosslinks and microcrystallites were formed due to hydrogen bonds during the drying process after gelation. The hydrogen bonds were partly destroyed in a rich solvent, but the residual hydrogen bonds had an essential role in determining the swelling behavior in a poor solvent. The swelling behavior and the possible phase transition of the present system are discussed in terms of the solubility of polymers with different degrees of hydrolysis in given mixed solvents and in terms of the formation and destruction of physical crosslinks in the chemical PVA gels. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1978–1986, 2010
Flow‐induced particle orientation and rheological properties of suspensions of organoclays in thermoplastic resins
Authors: Rajabian Mahmoud , Naderi Ghasem , Carreau Pierre J. , Dubois Charles 
Published: August 2010

AbstractThe influence of nano‐scale particles on the viscoelastic properties of polymer suspensions is investigated. We have developed a simulation technique for the particle orientation and polymer conformation tensors to study various features of the suspensions. The nano‐particles are modeled as thin rigid oblate spheroid particles and the polymers as FENE‐P type viscoelastic and Newtonian fluid. Both interparticle and polymer‐particle interactions have been taken into account in our numerical computations. The nonlinear viscoelastic properties of nanocomposites of layered silicate particles in non‐Newtonian fluids are examined at the start‐up of shear flow and are interpreted using the model to examine the effects of model parameters as well as flow conditions on particle orientation, viscosity, and first normal stress difference of the suspensions. We have studied the microstructure of polymer‐clay nanocomposites using X‐ray diffraction (XRD) scattering and transmission electron microscopy (TEM). The rheology of these nanocomposites in step‐shear is shown to be fairly well predicted by the model. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 2003–2011, 2010
Identification and Imaging of 15N labeled cells with ToF‐SIMS
Authors: Tyler Bonnie J. , Takeno Marc M. , Hauch Kip D. 
Published: August 2010

AbstractStable isotope labeling may provide a novel method for tracking stem cells once they have been injected into a human or animal host. Here, we present a simple pilot study to determine the potential for using ToF‐SIMS to detect and localize 15N labeled cells in tissue biopsies for use in cell therapy studies. For this pilot study, 3T3 fibroblasts were grown in normal media and in two different media containing 15N labeled amino acids. Samples containing a mixture of 15N labeled and unlabeled cells were prepared, fixed and dried for analysis and were then imaged using a bunched Bi3+ primary ion source. The cells containing 15N labeled amino acids could be readily distinguished using nitrogen‐containing peaks which have been previously associated with the labeled amino acids. Contrast was sufficient to allow easy identification of labeled cells in both sparsely and densely plated cultures. Multivariate analysis showed that the image contrast could be improved by including peaks originating from characteristic fragments of the labeled amino acids as well as lower mass NH4+ and CH4N+ peaks. Additional work is being pursued to determine and improve the longevity of the label. Copyright © 2010 John Wiley & Sons, Ltd.
The Retinoid Signaling Pathway Inhibits Hematopoiesis and Uncouples from the Hox Genes During Hematopoietic Development
Authors: Szatmari Istvan , Iacovino Michelina , Kyba Michael 
Published: August 2010

Abstract
Retinoic acid (RA) is a well-established inducer of Hox genes during development of neurectoderm, however effects of RA on Hox expression are poorly defined in mesoderm and not defined in the hematopoietic compartment. Both Hox genes and retinoid signaling have been suggested to modulate hematopoietic stem cell (HSC) self-renewal, supporting the notion that RA signaling might drive HSC self-renewal through Hox gene induction. Here, we investigate this possibility by comprehensively evaluating Hox gene expression using mouse embryonic stem cells differentiated in vitro. In unspecified mesoderm, we find that RA coordinately upregulates anterior 3′ Hox genes from clusters A, B, and C, and downregulates posterior 5′ Hox genes from clusters A–D. However, hematopoietic development of mesoderm was inhibited by RA, and we find further that retinoids are entirely dispensable for hematopoiesis in vitro. More surprisingly, in fully specified hematopoietic progenitors, Hox genes are refractory to regulation by RA, although other RA targets are normally regulated. Pulses of RA exposure demonstrate that the Hox complexes are decoupled from RA regulation progressively in lateral plate mesoderm as it undergoes hematopoietic specification. Thus, Hox genes are targets of the RA pathway only in selected cell types, and are clearly not regulated by RA in the earliest hematopoietic progenitors. We propose that the developmental uncoupling of the Hox complexes protects the Hox code from potential RA signaling centers as HSCs migrate or circulate during development.
Notch Activation Differentially Regulates Renal Progenitors Proliferation and Differentiation Toward the Podocyte Lineage in Glomerular Disorders
Authors: Lasagni Laura , Ballerini Lara , Angelotti Maria Lucia , Parente Eliana , Sagrinati Costanza , Mazzinghi Benedetta , Peired Anna , Ronconi Elisa , Becherucci Francesca , Bani Daniele , Gacci Mauro , Carini Marco , Lazzeri Elena , Romagnani Paola 
Published: August 2010

Abstract
Glomerular diseases account for 90% of end-stage kidney disease. Podocyte loss is a common determining factor for the progression toward glomerulosclerosis. Mature podocytes cannot proliferate, but recent evidence suggests that they can be replaced by renal progenitors localized within the Bowman's capsule. Here, we demonstrate that Notch activation in human renal progenitors stimulates entry into the S-phase of the cell cycle and cell division, whereas its downregulation is required for differentiation toward the podocyte lineage. Indeed, a persistent activation of the Notch pathway induced podocytes to cross the G2/M checkpoint, resulting in cytoskeleton disruption and death by mitotic catastrophe. Notch expression was virtually absent in the glomeruli of healthy adult kidneys, while a strong upregulation was observed in renal progenitors and podocytes in patients affected by glomerular disorders. Accordingly, inhibition of the Notch pathway in mouse models of focal segmental glomerulosclerosis ameliorated proteinuria and reduced podocyte loss during the initial phases of glomerular injury, while inducing reduction of progenitor proliferation during the regenerative phases of glomerular injury with worsening of proteinuria and glomerulosclerosis. Taken altogether, these results suggest that the severity of glomerular disorders depends on the Notch-regulated balance between podocyte death and regeneration provided by renal progenitors.
The efficacy of laparoscopic uterosacral nerve ablation (LUNA) in the treatment of unexplained chronic pelvic pain: a randomized controlled trial
Authors: El-Din Shawki Hossam 
Published: August 2010

AbstractThe aim of this work is to explore the efficacy , safety, and patients' satisfaction of laparoscopic uterosacral nerve ablation (LUNA) in relief of pain in women with chronic pelvic pain in whom diagnostic laparoscopy reveals either no pathology or mild endometriosis (AFS score ≤5). The study was a prospective, single-blind, randomized trial with 12 months follow-up. It was conducted at the endoscopy unit of the Gynecology Department of El Minia University Hospital, Egypt. One hundred ninety Egyptian women consented to participate in the study. These eligible patients were randomized using computer-generated tables and were divided into two equal groups, including the control group (diagnostic laparoscopy with no pelvic denervation) and the study group (diagnostic laparoscopy plus LUNA). Diagnostic laparoscopy with or without laparoscopic uterosacral nerve ablation was done. There were no statistically significant difference between both groups regarding the efficacy and the overall success rate (between group I and group II, it was 77.64%, 76.47%, and 74.11% versus 79.06%, 75.58%, and 73.25% at 3, 6, and 12 months, respectively) and the cumulative patients' satisfaction rate (it was 74.11%, 74.11%, and 71.76% versus 75.58%, 75.58%, and 72.09% at 3, 6, and 12 months between group I and group II, respectively; P ≤ 0.05). There was no statistically significant difference between both groups as regards the effectiveness of LUNA in the treatment of primary (spasmodic) and secondary (congestive) dysmenorrhea (P ≤ 0.05), while there was a statistically significant difference between both groups in the treatment of dyspareunia (P ≥ 0.05). LUNA can be a last alternative option in well-selected patients for control of chronic pelvic pain without endometriosis; however, its effectiveness may not extend to other indications. Also, preliminary experience in the treatment of primary deep dyspareunia presents a promising perspective on the management of deep dyspareunia, especially if it will involve a team of social, psychological, and gynecological specialists.
Fertility preservation for boys with cancer
Authors: Fujita Kazutoshi , Tsujimura Akira 
Published: August 2010

AbstractChildhood cancer is a curable disease due to the development of chemo‐ and radiation therapies, but long‐term survivors suffer late side‐effects including infertility. Cytotoxic agents and radiation impair spermatogenesis and cause oligospermia or azoospermia as well as genetic damage in sperm. To date, the only established option to preserve fertility is cryopreservation of sperm before treatment and artificial reproduction techniques, if men with cancer can ejaculate, but only a quarter of men have banked sperm. Lack of information is the most common reason for failing to bank sperm. However, prepubertal patients who have only spermatogonia and spermatocytes in their testes do not benefit from cryopreservation of their sperm and assisted reproductive techniques. Thus, the only available option is to harvest testicular tissues before treatment for cryopreservation, from which immature germ cells can somehow be maturated. Autotransplantation of germ cells into the testis holds promise for fertility restoration, but contamination by malignant cells may induce relapse. Fluorescence‐activated cell sorting (FACS) with two surface markers could exclude contaminated leukemic cells from murine germ cells, and transplantation of sorted germ cells successfully restored fertility without transmission of leukemia. Human germ cells could be also isolated from human leukemia and lymphoma cell lines by FACS using surface markers. Before autotransplantation can be applied clinically, some issues, including the risk of contamination by malignant cells and in vitro propagation of spermatogonial stem cells, should be resolved.
Easier is not always better: The moderating role of processing type on preference fluency
Authors: Nielsen Jesper H. , Escalas Jennifer Edson 
Published: August 2010

AbstractPrior research has shown that preference fluency (i.e., the subjective feeling that forming a preference is easy or difficult) systematically influences consumer choices. When deciding on an option feels difficult, or requires effort, consumers are likely to select a different option or defer the decision. We find that under conditions of narrative processing, difficulty in processing can actually improve preferences because more effort leads to more transportation, or immersion, into the story, thus enhancing brand evaluations. Three experiments demonstrate that the effect of preference fluency reverses when consumers think about a brand as part of a story.
A globally important wild yak Bos mutus population in the Arjinshan Nature Reserve, Xinjiang, China
Authors: Buzzard Paul J. , Zhang Hui Bin , Xü Dong Hua , Wong How Man 
Published: August 2010

AbstractThe wild yak Bos mutus is one of the most charismatic members of the Tibet/Qinghai Plateau fauna, and 19th century explorers to the plateau described vast herds. Overhunting, in particular, has greatly reduced wild yak populations and forced them into remote areas. The species is categorized as Vulnerable on the IUCN Red List and as a Class 1 protected animal in China. Introgression with domestic yaks is another threat, and the wild yak population of the Arjinshan Nature Reserve is particularly important because Uigher herders in and around Arjinshan do not have the tradition of raising yaks. We provide information on the status of the wild yak in Arjinshan based on observations in 1993 and on vehicle surveys during 1998–2009 and point samples from 2009. The steppes of north-east Arjinshan are the most important area, and we saw c. 1,700 yaks there in winter 2008. We saw more yaks in the north-east on similar routes driven in winter 2008 compared to winter 2005, suggesting that the wild yak population in Arjinshan is stable or increasing.