bluuebunny/crossref_metadata_2025 huggingface dataset:
Long‐term assessment of seed provenance effect on the establishment of the perennial grass Bromus erectus
Authors: Zeiter Michaela , Stampfli Andreas
Published: May 2008

Questions:

Do short‐term seed‐addition experiments reliably tell us about seed limitation of perennial species? Does seed provenance affect recruitment success?

Location:

Three dry grassland sites (Negrentino, Poma, San Giorgio), southern Switzerland.

Methods:

18 000 seeds of Bromus erectus of three provenances were sown in a reciprocal design with temporal replication. Frequent checks were made of all emerged individuals of two seed cohorts over three years and continued annual checks of one cohort until year eight. Performance was determined by number and size of emerging and surviving individuals and a combined measure of population vigour.

Results:

From a three‐year perspective, all sites appeared to be seed limited, and differences due to seed provenance were small. Over five years, two sites showed an increasingly superior performance of the local over the foreign populations. At one of these two sites, average individuals remained small and a decrease in number and individual phytomass since the fifth year suggested complete microsite limitation. Reproductive individuals only occurred at the other sites and confirmed seed limitation after eight years. The best performing site had the first reproductive individuals in the fourth year.

Conclusions:

B. erectus showed a long pre‐reproductive phase during which the prediction of establishment success by individual counts can be misleading if plant size is not also measured. The effect of seed provenance was clearly indicated where populations established most successfully and local‐over‐foreign superiority increased with time.
Caffeine Induces Cell Death via Activation of Apoptotic Signal and Inactivation of Survival Signal in Human Osteoblasts
Authors: Lu Pin-Zhen , Lai Ching-Yu , Chan Wen-Hsiung
Published: May 2008

Caffeine consumption is a risk factor for osteoporosis, but the precise regulatory mechanisms are currently unknown. Here, we show that cell viability decreases in osteoblasts treated with caffeine in a dose-dependent manner. This cell death is attributed primarily to apoptosis and to a smaller extent, necrosis. Moreover, caffeine directly stimulates intracellular oxidative stress. Our data support caffeine-induced apoptosis in osteoblasts via a mitochondria-dependent pathway. The apoptotic biochemical changes were effectively prevented upon pretreatment with ROS scavengers, indicating that ROS plays a critical role as an upstream controller in the caffeine-induced apoptotic cascade. Additionally, p21-activated protein kinase 2 (PAK2) and c-Jun N-terminal kinase (JNK) were activated in caffeine-treated osteoblasts. Experiments further found that PAK2 activity is required for caffeine-induced JNK activation and apoptosis. Importantly, our data also show that caffeine triggers cell death via inactivation of the survival signal, including the ERK- and Akt-mediated anti-apoptotic pathways. Finally, exposure of rats to dietary water containing 10~20 μM caffeine led to bone mineral density loss. These results demonstrate for the first time that caffeine triggers apoptosis in osteoblasts via activation of mitochondria-dependent cell death signaling and inactivation of the survival signal, and causes bone mineral density loss in vivo.
Metabolic Compartmentation – A System Level Property of Muscle Cells
Authors: Saks Valdur , Beraud Nathalie , Wallimann Theo
Published: May 2008

Problems of quantitative investigation of intracellular diffusion and compartmentation of metabolites are analyzed. Principal controversies in recently published analyses of these problems for the living cells are discussed. It is shown that the formal theoretical analysis of diffusion of metabolites based on Fick’s equation and using fixed diffusion coefficients for diluted homogenous aqueous solutions, but applied for biological systems in vivo without any comparison with experimental results, may lead to misleading conclusions, which are contradictory to most biological observations. However, if the same theoretical methods are used for analysis of actual experimental data, the apparent diffusion constants obtained are orders of magnitude lower than those in diluted aqueous solutions. Thus, it can be concluded that local restrictions of diffusion of metabolites in a cell are a system-level properties caused by complex structural organization of the cells, macromolecular crowding, cytoskeletal networks and organization of metabolic pathways into multienzyme complexes and metabolons. This results in microcompartmentation of metabolites, their channeling between enzymes and in modular organization of cellular metabolic networks. The perspectives of further studies of these complex intracellular interactions in the framework of Systems Biology are discussed.
Enantioselective Synthesis of cis‐4‐Formyl‐β‐lactams via Chiral N‐Heterocyclic Carbene‐Catalyzed Kinetic Resolution
Authors: Li Gong‐Qiang , Li Yi , Dai Li‐Xin , You Shu‐Li
Published: May 2008

An efficient synthesis of optically pure cis‐4‐formyl‐β‐lactams (up to 99% ee) by a chiral NHC‐catalyzed ring expansion reaction has been realized, featuring the ready availability of both the substrate and the catalyst, and the mild reaction conditions. The current method is also suitable for the synthesis of enantioenriched 4‐formyl‐β‐lactams and succinimides containing quaternary carbon centers.
Preparation of (R)‐Amines from Racemic Amines with an (S)‐Amine Transaminase from Bacillus megaterium
Authors: Hanson Ronald L. , Davis Brian L. , Chen Yijun , Goldberg Steven L. , Parker William L. , Tully Thomas P. , Montana Michael A. , Patel Ramesh N.
Published: May 2008

Screening was carried out to identify strains useful for the preparation of (R)‐1‐cyclopropylethylamine and (R)‐sec‐butylamine by resolution of the racemic amines with an (S)‐specific transaminase. Several Bacillus megaterium strains from our culture collection as well as several soil isolates were found to have the desired activity for the resolution of the racemic amines to give the (R)‐enantiomers. Using an extract of the best strain, Bacillus megaterium SC6394, the reaction was shown to be a transamination requiring pyruvate as amino acceptor and pyridoxal phosphate as a cofactor. Initial batches of both amines were produced using whole cells of Bacillus megaterium SC6394. The transaminase was purified to homogeneity to obtain N‐terminal as well as internal amino acid sequences. The sequences were used to design polymerase chain reaction (PCR) primers to enable cloning and expression of the transaminase in E. coli SC16578. In contrast to the original B. megaterium process, pH control and aeration were not required for the resolution of sec‐butylamine and an excess of pyruvate was not consumed by the recombinant cells. The resolution of sec‐butylamine (0.68 M) using whole cells of E. coli SC16578 was scaled up to give (R)‐sec‐butylamine⋅1/2 H2SO4 in 46.6% isolated yield with 99.2% ee. An alternative isolation procedure was also used to isolate (R)‐sec‐butylamine as the free base.
Highly Efficient Metal‐Free Cross‐Coupling by CH Activation between Allylic and Active Methylenic Compounds Promoted by DDQ
Authors: Cheng Dongping , Bao Weiliang
Published: May 2008

A metal‐free very highly efficient and concise oxidative‐coupling reaction promoted by 2,3‐dichloro‐5,6‐dicyanoquinone (DDQ) between diarylallylic sp3 CH and active methylenic sp3 CH bonds is reported. The corresponding products are obtained in good to excellent yields.
Polystyryl‐BEMP as an Efficient Recyclable Catalyst for the Nucleophilic Addition of Nitroalkanes to α,β‐Unsaturated Carbonyl Compounds under Solvent‐Free Conditions
Authors: Ballini R. , Barboni L. , Castrica L. , Fringuelli F. , Lanari D. , Pizzo F. , Vaccaro L.
Published: May 2008

2‐tert‐Butylimino‐2‐diethylamino‐1,3‐dimethylperhydro‐1,3,2‐diazaphosphorine supported on polystyrene (PS‐BEMP) is an efficient catalyst for the addition of nitroalkanes (1–1.5 equiv.) to α,β‐unsaturated carbonyl compounds (1.0 equiv.) in the absence of a reaction medium (solvent‐free conditions). The corresponding γ‐nitro carbonyl compounds have been isolated in excellent yields but the catalyst can be satisfactorily recovered and used for only 3 times due to the magnetic stirring which caused crunching of the catalyst beads thus hampering its complete recovery. To optimize the catalyst’s reuse and improve the environmental efficacy of solvent‐free conditions, the first solvent‐free cyclic continuous‐flow reactor has been set up. This reactor has allowed the product to be isolated in an almost quantitative yield by using a very small amount of organic solvent, making the recovery and reuse of the catalyst efficient and reproducible.
Multimode process monitoring with Bayesian inference‐based finite Gaussian mixture models
Authors: Yu Jie , Qin S. Joe
Published: May 2008

For complex industrial processes with multiple operating conditions, the traditional multivariate process monitoring techniques such as principal component analysis (PCA) and partial least squares (PLS) are ill‐suited because the fundamental assumption that the operating data follow a unimodal Gaussian distribution usually becomes invalid. In this article, a novel multimode process monitoring approach based on finite Gaussian mixture model (FGMM) and Bayesian inference strategy is proposed. First, the process data are assumed to be from a number of different clusters, each of which corresponds to an operating mode and can be characterized by a Gaussian component. In the absence of a priori process knowledge, the Figueiredo–Jain (F–J) algorithm is then adopted to automatically optimize the number of Gaussian components and estimate their statistical distribution parameters. With the obtained FGMM, a Bayesian inference strategy is further utilized to compute the posterior probabilities of each monitored sample belonging to the multiple components and derive an integrated global probabilistic index for fault detection of multimode processes. The validity and effectiveness of the proposed monitoring approach are illustrated through three examples: (1) a simple multivariate linear system, (2) a simulated continuous stirred tank heater (CSTH) process, and (3) the Tennessee Eastman challenge problem. The comparison of monitoring results demonstrates that the proposed approach is superior to the conventional PCA method and can achieve accurate and early detection of various types of faults in multimode processes. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Clinical and prognostic features of plasmacytomas: A multicenter study of Turkish Oncology Group‐Sarcoma Working Party
Authors: Kilciksiz Sevil , Celik Omur Karakoyun , Pak Yucel , Demiral Ayse Nur , Pehlivan Mustafa , Orhan Okan , Tokatli Fusun , Agaoglu Fulya , Zincircioglu Burhanedtin , Atasoy Beste Melek , Ozseker Naciye , Yersal Ozlem , Niang Umar , Haydaroglu Ayfer
Published: May 2008

To identify the outcomes of prognostic factors of solitary plasmacytoma mainly treated with local radiotherapy (RT). The data were collected from 80 patients with solitary plasmacytoma (SP). Forty patients (50.0%) received radiotherapy (RT) alone while 38 of them (47.5%) were treated with surgery (S) and RT. The median radiation dose was 46 Gy (range 30–64). The median follow up was 2.41 years (range 0.33–12.33). Ten‐year overall survival (OS) and local relapse‐free survival (LRFS) were 73% and 94%, respectively. The median progression‐free survival (PFS) and multiple myeloma‐free survival (MMFS) were 3.5 years and 4.8 years, respectively. On multivariate analyses, the favorable factors were radiotherapy dose of ≥50 Gy and RT + S for PFS and younger age for MMFS. For the patients with medullary plasmacytoma, the favorable factor was younger age for MMFS. RT at ≥50 Gy and RT + S may be favorable prognostic factors on PFS. Younger patients, especially with head‐neck lesion and without pre‐RT macroscopic tumor, seem to have the best outcome when treated with RT ± S. Progression to MM remains as the main problem especially for older patients. Am. J. Hematol., 2008. © 2008 Wiley‐Liss, Inc.
Pilot study of continuous co‐infusion of morphine and naloxone in children with sickle cell pain crisis
Authors: Koch Josh , Manworren Renee , Clark Lynn , Quinn Charles T. , Buchanan George R. , Rogers Zora R.
Published: May 2008

Patients with sickle cell disease experience painful crises that often require hospitalization for a continuous infusion of morphine that may cause significant pruritus. We conducted a pilot study to determine the feasibility of simultaneous continuous co‐infusion of naloxone with morphine, test novel assessment instruments for pruritus, and explore whether pruritus could be reduced while maintaining effective analgesia. Patients with sickle cell disease and painful crisis requiring continuous infusion morphine received continuous co‐infusion of naloxone at 0.25 (low dose) or 1.0 mcg/kg·hr (high dose). Pain scores were obtained using the FACES scale and a 100‐mm visual analog scale (VAS). Itching was quantified by a modified VAS score. Evaluable data were obtained on 16 patients. Simultaneous co‐infusion of naloxone and morphine was feasible, did not seem to reduce the analgesic efficacy of morphine, and was associated with no adverse effects. The high dose group reported a lower median “VAS worst itch” score than the low dose group (4.8 vs. 7.3, P = 0.08). Simultaneous continuous infusion of naloxone with morphine in pediatric patients with sickle cell disease and pain crisis was feasible and well tolerated. A quantitative pruritus score allowed us to systematically measure pruritus. Further evaluation by randomized, placebo‐controlled study of 1 mcg/kg·hr naloxone in this setting is required. Am. J. Hematol., 2008. © 2008 Wiley‐Liss, Inc.
Impact of alemtuzumab as conditioning regimen component on transplantation outcomes in case of CMV‐seropositive recipients and donors
Authors: Chae Yee Soo , Sohn Sang Kyun , Kim Jong Gwang , Cho Yoon Young , Moon Joon Ho , Yang Deok Hwan , Lee Je‐Jung , Kim Yeo‐Kyeoung , Kim Hyeoung‐Joon , Shin Ho Jin , Chung Joo Seop , Cho Goon Jae
Published: May 2008

We studied the incidence of cytomegalovirus (CMV) infection, clinical outcomes, and complications in 39 recipients of alemtuzumab‐containing conditioning‐stem cell transplantation, who were classified into two groups based on the median dose (35 mg) of alemtuzumab. All the recipients and donors were CMV‐seropositive before transplantation. The median survival duration was 321 days (range, 46–1098 days) and the 2‐year survival rate was 47.8%. The probability of nonrelapse mortality at 100 days and 2 years was 14.6% and 31.2%, respectively. The cumulative incidence of Grade II‐IV acute graft‐versus‐host disease (GVHD) at Day 100 was 21.8%. The overall incidence of chronic GVHD (cGVHD) was 28.6%, including a 17.9% incidence of extensive cGVHD. The cumulative incidence of CMV antigenemia was 68.0%. There were no statistical differences in the engraftment, acute and cGVHD, relapse, CMV antigenemia, and overall survival (OS) between the two groups. Yet, the nonrelapse mortality (NRM) was significantly lower for the low‐dose group (5.9% vs. 51.7%, P = 0.010). The present study showed that alemtuzumab was effective for GVHD prevention, yet caused a relatively high incidence of CMV antigenemia, regardless of the dose. Thus, a low dose of alemtuzumab (≤ 35 mg) would seem to be preferable in an allogeneic SCT setting when both the recipient and the donor are CMV seropositive. Am. J. Hematol., 2008. © 2008 Wiley‐Liss, Inc.
Evolution of ADAMTS13 antibodies in a fatal case of thrombotic thrombocytopenic purpura
Authors: Dong Lingli , Chandrasekaran Visalam , Zhou Wenhua , Tsai Han‐Mou
Published: May 2008

In a patient with fatal thrombotic thrombocytopenic purpura, the inhibitory activity of antibodies against ADAMTS13 rapidly escalated to extremely high levels despite daily plasma exchange and corticosteroid therapy. This increase was found to be because of a combination of higher antibody concentration and potency. Furthermore, during her course of the disease, the percentage of IgG1 antibody progressively decreased whereas that of IgG2 antibody increased, suggesting Th1‐type cytokine response. These changes suggest that the course of TTP may be exacerbated by complex immune reactions. Further characterization of the factors contributing to this exacerbation may have important pathogenetic and therapeutic implications. Am. J. Hematol., 2008. © 2008 Wiley‐Liss, Inc.
Young–Simpson syndrome (YSS), a variant of del(1)(p36) syndrome?
Authors: Robinson Deanne Mraz , Meagher Cecilia C. , Orlowski Craig C. , Lagoe Erin Caine , Fong Chin‐To
Published: May 2008

The Young–Simpson syndrome (YSS) and 1p36 deletion syndrome are both characterized by facial and heart abnormalities, congenital hypothyroidism, and severe growth and developmental retardation. However, the YSS is characterized by the presence of blepharophimosis and epicanthus inversus, findings not described in monosomy 1p36 patients. We describe a girl with YSS, who presented with the typical facial findings, global retardation, congenital hypothyroidism, and congenital dilated cardiomyopathy. Comparative genomic hybridization chromosomal microarray analysis showed a 1p36.3 deletion, a finding not previously reported in other YSS cases. We propose that YSS is a variant of the 1p36 deletion syndrome. © 2008 Wiley‐Liss, Inc.
Tetralogy of Fallot associated with pulmonary atresia and major aortopulmonary collateral arteries in a patient with interstitial deletion of 16q21–q22.1
Authors: Yamamoto Toshiyuki , Dowa Yuri , Ueda Hideaki , Kawataki Motoyoshi , Asou Toshihide , Sasaki Yuki , Harada Naoki , Matsumoto Naomichi , Matsuoka Rumiko , Kurosawa Kenji
Published: May 2008

A newborn male had an interstitial deletion of 16q21–q22.1 accompanying tetralogy of Fallot associated with pulmonary atresia and major aortopulmonary collateral arteries (MAPCA), dysmorphic craniofacial features, failure to thrive, and severe psychomotor developmental delay. When the deletion in this patient and other reported patients are compared, the 16q22 region appears to be the smallest region for 16q deletion syndrome. Since over 50% of patients with the deletion of 16q22 region have congenital heart disease, there may be a responsible gene in this region. © 2008 Wiley‐Liss, Inc.
Autosomal dominant spondylocarpotarsal synostosis syndrome: Phenotypic homogeneity and genetic heterogeneity
Authors: Isidor B. , Cormier‐Daire V. , Le Merrer M. , Lefrancois T. , Hamel A. , Le Caignec C. , David A. , Jacquemont S.
Published: May 2008

Spondylocarpotarsal synostosis syndrome (SCT) (OMIM 272460), originally thought to be a failure of normal spine segmentation, is characterized by progressive fusion of vertebras and associates unsegmented bars, scoliosis, short stature, carpal and tarsal synostosis. Cleft palate, sensorineural or mixed hearing loss, joint limitation, clinodactyly, and dental enamel hypoplasia are variable manifestations. Twenty‐five patients have been reported. Thirteen affected individuals were siblings from six families and four of these families were consanguineous. In four of those families, Krakow et al. [Krakow et al. (2004) Nat Genet 36:405–410] found homozygosity or compound heterozygosity for mutations in the gene encoding FLNB. This confirmed autosomal recessive inheritance of the disorder. We report on two new patients (a mother and her son) representing the first case of autosomal dominant inheritance. These patients met the clinical and radiological criteria for SCT and did not present any features which could exclude this diagnosis. Molecular analysis failed to identify mutations in NOG and FLNB. SCT is therefore, genetically heterogeneous. Both dominant and autosomal recessive forms of inheritance should be considered during genetic counseling. © 2008 Wiley‐Liss, Inc.
Boundaries and clines in the West Eurasian Y‐chromosome landscape: Insights from the European part of Russia
Authors: Fechner Angela , Quinque Dominique , Rychkov Sergey , Morozowa Irina , Naumova Oksana , Schneider Yuriy , Willuweit Sascha , Zhukova Olga , Roewer Lutz , Stoneking Mark , Nasidze Ivan
Published: May 2008

Previous studies of Y chromosome variation have revealed that western Europe, the Volga‐Ural region, and the Caucasus differ dramatically with respect to Y‐SNP haplogroup composition. The European part of Russia is situated in between these three regions; to determine if these differences reflect clines or boundaries in the Y‐chromosome landscape, we analyzed 12 Y‐SNPs in 545 males from 12 populations from the European part of Russia. The majority of Russian Y chromosomes (from 74% to 94%) belong to three Y chromosomal lineages [I‐M170, R1a1‐M17, and N3‐TAT] that are also frequent in the rest of east Europe, north Europe, and/or in the Volga‐Ural region. We find significant but low correlations between haplogroup frequencies and the geographic location of populations, suggesting gradual change in the Y chromosome gene pool across western Eurasia. However, we also find some significant boundaries between populations, suggesting that both isolation and migration have influenced the Y chromosome landscape. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.
Placental efficiency and intrauterine resource allocation strategies in the common marmoset pregnancy
Authors: Rutherford Julienne N. , Tardif Suzette D.
Published: May 2008

Mothers and fetuses are expected to be in some degree of conflict over the allocation of maternal resources to fetal growth in the intrauterine environment. Variation in placental structure and function may be one way a fetus can communicate need and quality to its mother, potentially manipulating maternal investment in its favor. Whereas common marmosets typically produce twin litters, they regularly give birth to triplet litters in captivity. The addition of another fetus is a potential drain on maternal resource availability and thus a source of elevated conflict over resource allocation. Marmoset littermates share a single placental mass, so that differences in the ratio of fetal to placental weight across litter categories suggest the presence of differential intrauterine strategies of resource allocation. The fetal/placental weight ratio was calculated for 26 marmoset pregnancies, representing both twin and triplet litters, to test the hypothesis that triplet fetuses respond to intrauterine conflict by soliciting placental overgrowth as a means of accessing maternal resources. In fact, relative to fetal mass, the triplet marmoset placenta is significantly undergrown, with individual triplets associated with less placental mass than their twin counterparts, suggesting that the triplet placenta is relatively more efficient in its support of fetal growth. There still may be an important role for maternal‐fetal conflict in the programming of placental structure and function. Placental adaptations that solicit potential increases of maternal investment may occur at the microscopic or metabolic level, and thus may not be reflected in the size of the placenta as a whole. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.
Manual lateralization in early primates: A comparison of two mouse lemur species
Authors: Leliveld Lisette M.C. , Scheumann Marina , Zimmermann Elke
Published: May 2008

In humans, 90% of the population is right handed. Although population hand preference has been found in some primate species, the evolution of manual lateralization in primates is not yet clear. To gain insight into manual lateralization of ancestral primates, we studied hand usage in unspecialized quadrupedal, nocturnal lemurs, using a large sample size. We compared two closely related mouse lemur species to explore the variation of hand preference within the same genus. We tested 44 gray mouse lemurs and 19 Goodman's mouse lemurs in a forced food grasping task. The tests were videotaped. Measures of hand preference (i.e. the hand that is spontaneously chosen for a specific task) and successful hand usage (i.e. the hand that is successful in completing a specific task) were taken to explore manual lateralization. Both species showed manual lateralization at an individual, but not at a population level. Goodman's mouse lemurs showed stronger individual hand preferences than gray mouse lemurs. This suggests that strength in hand preference is variable within the same genus. No sex and age effects were found. The hand preference of offspring was negatively correlated to that of their mothers, but not correlated to that of their fathers. Thus, no clear genetic effect can be derived from these results. In the Goodman's mouse lemurs, hand preference increased with increasing task experience. However, successful hand usage was not affected by task experience, suggesting that successful hand usage is a more stable measurement for manual lateralization than hand preference. Am J Phys Anthropol, 2008. © 2008 Wiley‐Liss, Inc.
Fractal analysis of morphology of PE/PA blends: Composition
Authors: Chen Xu‐Huang , Shi Wen‐Xiong , Yang Shi‐Hai , Li Yun‐Yan , Ma Gui‐Qiu , Sheng Jing
Published: May 2008

Composition effect on the phase morphology in polyethylene (PE) with polyamide (PA) blends was investigated by pattern analysis of scanning electron micrographs. The average diameter denoted as dg is defined to discuss the morphology of the blends and further, different fractal dimensions, DM and DN, were introduced to characterize the phase morphology. Scale function SN(r) and SM(r) are defined to study the selfsimilarity of the phase morphology. The plots of SN(r)/SN(r)m (the maximum of SN(r)) versus r/rm (the maximum of r) and SM(r)/SM(r)m (the maximum of SM(r)) versus r/rm showed the selfsimilar formation of the phase pattern. Furthermore, we calculated the fractal dimension D of different PE/PA blends. The results showed that the fractal dimension was an effective parameter to describe the spacial distribution of dispersed particles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Polyethylene/boron nitride composites for space radiation shielding
Authors: Harrison Courtney , Weaver Sean , Bertelsen Craig , Burgett Eric , Hertel Nolan , Grulke Eric
Published: May 2008

Composites made with boron might be absorbers of low energy neutrons, and could be used for structural materials for spacecraft. Polyethylene/boron nitride composites were fabricated using conventional polymer processing techniques, and were evaluated for mechanical and radiation shielding properties. The boron nitride powder surfaces were also functionalized to improve interfacial adhesion. Addition of neat boron nitride to an injection molding grade HDPE increased the tensile modulus from 588 to 735 MPa with 15 vol % filler. The bonding of a trifunctional alkoxysilane to the powder surface prior to processing increases the composite modulus to 856 MPa at the same loading. Scanning electron microscopy of fracture surfaces verified that the silane‐treated powders had improved adhesion at the filler/polymer interface. Radiation shielding measurements of a 2 wt % boron nitride composite were improved over those of the neat polyethylene. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis, characterization, and adsorption capacity of crosslinked starch microspheres with N,N′‐methylene bisacrylamide
Authors: Zhao Xin‐Fa , Li Zhong‐Jin , Wang Lei , Lai Xiao‐Juan
Published: May 2008

Crosslinked starch microspheres (CSMs) were prepared in an inverse suspension system. Scanning electron microscopy observation indicated that the CSMs were uniform in granularity with a smooth spherical particulate surface. The particle size analysis revealed that the average diameter was 18.2 μm and that 85.8% of the microspheres were of a diameter below 30 μm. The structural characteristics of the carbonyl group and the second acrylamide by Fourier transform infrared spectroscopy of the CSMs showed that the soluble starch obviously crosslinked with N,N′‐methylene bisacrylamide. The physical properties of the CSMs were analyzed by way of X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The results show that the crosslinking resulted in an increase in thermal stability and a decrease in crystallinity of the CSMs compared with soluble starch. The adsorption capacity of the CSMs increased with increasing concentration of methylene blue. The lower temperature was in favor of the adsorption capacity of the CSMs. The adsorption mode of methylene blue by the CSMs agreed more with the Langmuir isothermal equation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and characterization of organically modified attapulgite/polyurethane nanocomposites
Authors: Wang Chia‐Hao , Auad Maria L. , Marcovich Norma E. , Nutt Steven
Published: May 2008

Polyurethane (PU) nanocomposites filled with attapulgite (ATT) nanorods were synthesized and characterized with thermal analysis, dynamic mechanical analysis (DMA), and mechanical testing. The formulations were based on 4,4′‐methylene bis(phenyl isocyanate) (MDI), polytetrahydrofuran, 1,4‐butanediol, and inorganic ATT premodified with MDI. The original and premodified ATT (ATT–OH and ATT–MDI) nanorods were characterized with thermogravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectroscopy. The analysis revealed that 17 wt % MDI was grafted/adsorbed onto the surface of ATT as a result of the modification. Pristine PU and ATT–MDI/PU nanocomposites were characterized with scanning electron microscopy, differential scanning calorimetry, and TGA. The mechanical tests and DMA showed an increase in the storage modulus and Young's modulus with increasing ATT–MDI content. The crystallinity of the hard and soft segments and thermal stability showed enhancements over those of the neat resin. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Network structure/mechanical property relationship in multimethacrylates—Derivatives of nadic anhydride
Authors: Podgórski Maciej , Matynia Tadeusz
Published: May 2008

In this article the syntheses of dimethacrylate and trimethacrylate esters as well as the mechanical and thermal properties of their copolymers with methyl methacrylate and styrene are investigated. The esters were obtained from acidic derivatives of nadic anhydride and glycidyl methacrylate. The addition reaction of glycidyl methacrylate and the acidic compound was carried out in the presence of basic catalyst—tetraethylammonium bromide. The monomers and resins were UV cured in the presence of a suitable photoinitiator which was 2,2‐dimethoxy‐2‐phenyloacetophenone. The prepared polymers were subjected to different studies concerning evaluation of their mechanical properties, thermal stability, dynamic mechanical behavior (DMA) as well as the estimation of the content of unreacted double bonds in the final product. The results proved their good thermal and mechanical properties. The degree of unsaturated bonds conversion was found to be growing with the amount of monovinyl monomer in the copolymer. Trimethacrylate‐based copolymers are characterized by a greater content of double bonds present in the obtained material compared to that of dimethacrylate‐based copolymers. As indicated by DMA the network structures of the copolymers seem to be more heterogeneous with the increasing weight fraction of trimethacrylate as well as dimethacrylate monomer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Study on the acidic hydrolysis process of poly(N‐vinylformamide/acrylonitrile) fiber
Authors: Chen Quan , Dong Liang , Ye Guangdou , Xu Jianjun
Published: May 2008

A convenient method of preparing chelating fiber with amine groups on the fiber surface was developed. The precursor polymer of Poly(N‐vinylformamide/acrylonitrile) (P(NVF/AN)) was synthesized via solution polymerization, using N‐vinylforaimde as a functional monomer. The solution of P(NVF/AN) was spun through a wet spinning method and the precursor fiber was hydrolyzed in the hydrochloric acid solution to convert formamide moieties to the corresponding amine. The influence of hydrolytic conditions on hydrolysis degree, such as hydrolysis temperature, hydrolysis time, and hydrochloric acid concentrations were examined experimentally. The hydrolysis degree of the precursor fiber was evaluated by potentiometric and conductometric titrations. The changes of the structure and properties of the fibers were characterized through infrared spectroscopy, scanning electron microscopy, and tensile strength tester. The results showed that the hydrolysis degree was limited in acidic hydrolysis because of the electrostatic repulsion among the cationic amine groups and proton. The hydrolysis degree of precursor fiber reached nearly 60%, and the chelating fiber remained the adequate mechanical properties under the suitable hydrolysis condition. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Influence of heat treatment on the properties of shape memory fibers. I. Crystallinity, hydrogen bonding, and shape memory effect
Authors: Meng Qinghao , Hu Jinlian
Published: May 2008

Shape memory fibers (SMFs) were prepared via melt spinning. The fibers underwent different heat treatments to eliminate internal stress and structure deficiency caused during melt spinning. The influences of heat treatments on the SMF crystallinity, molecular orientation, hydrogen bonding, and shape memory behavior were studied. It was found with increasing heat‐treatment temperature, the soft segment crystallinity, crystallite dimension, and microphase separation increased, and the hydrogen bonding in the hard segment phase increased. Low temperature heat treatments decreased the shape recovery ratios while increasing the shape fixity ratios as a result of internal stress releasing and molecules disorientation. High temperature heat treatments increased the hard segment stability. Increasing heat‐treatment temperature resulted in the improvement of both the shape recovery and fixity, because it promoted the phase separation. The results from DSC, DMA, XRD, and FTIR were used to illustrate the mechanism governing these properties difference. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Corrosion protective bi‐layered composites of polyaniline and poly(o‐anisidine) on low carbon steel
Authors: Chaudhari Sudeshna , Patil P. P.
Published: May 2008

Bi‐layered composites of polyaniline (PANI) and poly(o‐anisidine) (POA) were investigated for corrosion protection of low carbon steel (LCS). In this work, homopolymers and bi‐layers of PANI and POA were electropolymerized on LCS from an aqueous salicylate solution by using cyclic voltammetry. These coatings were characterized by cyclic voltammetry, Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). Corrosion tests were carried out in aqueous 3% NaCl solution for LCS coated with PANI, POA, bi‐layered POA/PANI (POA on top of the PANI) or PANI/POA (PANI on top of the POA) composites using open circuit potential (OCP) measurements, potentiodynamic polarization technique, and electrochemical impedance spectroscopy (EIS). The single layer of PANI and POA protected the LCS in 3% NaCl for 8 and 16 h, respectively. The bi‐layered composite coatings provide effective protection to LCS for a longer time than a single layered PANI or POA coating. However, the corrosion protection offered to LCS depends on the deposition order of polymer layers in the composite. The PANI/POA composite provides better protection to LCS against corrosion than POA/PANI coating. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis, characterization and swelling behavior of chitosan‐sucrose as a novel full‐polysaccharide superabsorbent hydrogel
Authors: Pourjavadi Ali , Aghajani Vagrik , Ghasemzadeh Hossein
Published: May 2008

A novel full‐polysaccharide hydrogel was prepared by crosslinking of chitosan with periodate‐oxidized sucrose. A tetraaldehyde molecule is synthesized via periodate oxidation of sucrose and then applied as a crosslinking agent to form a new hydrogel network. A mechanism for the superabsorbent hydrogel formation via reductive N‐alkylation was also suggested. The structure of the hydrogel was confirmed by FTIR spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). It is shown that crosslinking of chitosan can improve its thermal stability. The effects of crosslinker concentration, pH, and inorganic salt on the swelling behavior of the hydrogel were studied. The results indicate that the hydrogel has good pH sensitivity and pH reversible response. The smart hydrogels may have potential applications in the controlled delivery of bioactive agents and for wound‐dressing application © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Unsaturated Aldehydes as Alkene Equivalents in the Diels–Alder Reaction
Authors: Taarning Esben , Madsen Robert
Published: May 2008

A one‐pot procedure is described for using α,β‐unsaturated aldehydes as olefin equivalents in the Diels–Alder reaction. The method combines the normal electron demand cycloaddition with aldehyde dienophiles and the rhodium‐catalyzed decarbonylation of aldehydes to afford cyclohexenes with no electron‐withdrawing substituents. In this way, the aldehyde group serves as a traceless control element to direct the cycloaddition reaction. The Diels–Alder reactions are performed in a diglyme solution in the presence of a catalytic amount of boron trifluoride etherate. Subsequent quenching of the Lewis acid, addition of 0.3 % of [Rh(dppp)2Cl] and heating to reflux achieves the ensuing decarbonylation to afford the product cyclohexenes. Under these conditions, acrolein, crotonaldehyde and cinnamaldehyde have been reacted with a variety of 1,3‐dienes to afford cyclohexenes in overall yields between 53 and 88 %. In these transformations, the three aldehydes serve as equivalents of ethylene, propylene and styrene, respectively.
Studies of Finite Molecular Chains: Synthesis, Structural, Magnetic and Inelastic Neutron Scattering Studies of Hexa‐ and Heptanuclear Chromium Horseshoes
Authors: Ochsenbein Stefan T. , Tuna Floriana , Rancan Marzio , Davies Rachel S. G. , Muryn Christopher A. , Waldmann Oliver , Bircher Roland , Sieber Andreas , Carver Graham , Mutka Hannu , Fernandez‐Alonso Felix , Podlesnyak Andrew , Engelhardt Larry P. , Timco Grigore A. , Güdel Hans U. , Winpenny Richard E. P.
Published: May 2008

We report the synthesis and structural characterisation of a family of finite molecular chains, specifically [{[R2NH2]3[Cr6F11(O2CCMe3)10]}2] (in which R=nPr 1, Et 2, nBu 3), [{Et2NH}2{[Et2NH2]3[Cr7F12(O2CCMe3)12][HO2CCMe3]2}2] (4), [{[Me2NH2]3[Cr6F11(O2CCMe3)10]⋅2.5 H2O}4] (5) and [{[iPr2NH2]3[Cr7F12(O2CCMe3)12]}2] (6). The structures all contain horseshoes of chromium centres, with each Cr⋅⋅⋅Cr contact within the horseshoe bridged by a fluoride and two pivalates. The horseshoes are linked through hydrogen bonds to the secondary ammonium cations in the structure, leading to di‐ and tetra‐horseshoe structures. Through magnetic measurements and inelastic neutron scattering studies we have determined the exchange coupling constants in 1 and 6. In 1 it is possible to distinguish two exchange interactions, JA=−1.1 meV and JB=−1.4 meV; JA is the exchange interactions at the tips of the horseshoe and JB is the exchange within the body of the horseshoe (1 meV=8.066 cm−1). For 6 only one interaction was needed to model the data: J=−1.18 meV. The single‐ion anisotropy parameters for CrIII were also derived for the two compounds as: for 1, DCr=−0.028 meV and |ECr|=0.005 meV; for 6, DCr=−0.031 meV. Magnetic‐field‐dependent inelastic neutron scattering experiments on 1 allowed the Zeeman splitting of the first two excited states and level crossings to be observed. For the tetramer of horseshoes (5), quantum Monte Carlo calculations were used to fit the magnetic susceptibility behaviour, giving two exchange interactions within the horseshoe (−1.32 and −1.65 meV) and a weak inter‐horseshoe coupling of +0.12 meV. Multi‐frequency variable‐temperature EPR studies on 1, 2 and 6 have also been performed, allowing further characterisation of the spin Hamiltonian parameters of these chains.
Nitric Oxide Releasing Metal–Diazeniumdiolate Complexes Strongly Induce Vasorelaxation and Endothelial Cell Proliferation
Authors: Ziche Marina , Donnini Sandra , Morbidelli Lucia , Monzani Enrico , Roncone Raffaella , Gabbini Roberta , Casella Luigi
Published: May 2008

The preparation, characterization, and NO‐releasing properties of metal complexes derived from N‐aminoethylpiperazine‐N‐diazeniumdiolate (HPipNONO), [Cu(PipNONO)Cl] and [Ni(PipNONO)Cl], and the NiII complex derived from the Schiff base between HPipNONO and salicylaldehyde, [Ni(SalPipNONO)], are described. Compounds [Cu(PipNONO)Cl] and [Ni(SalPipNONO)] release NO at a much slower rate than HPipNONO in aqueous buffer in the pH range between 6.8 and 8.0. The kinetics of NO release by [Ni(SalPipNONO)] is complex, with an apparent stepwise release of NO molecules. Both [Cu(PipNONO)Cl] and [Ni(SalPipNONO)] are effective vasorelaxant agents of precontracted rabbit aorta rings, and are active in the nM concentration range. In addition, these complexes promote the proliferation of endothelial cells. Both vascular activities were inhibited by a specific inhibitor of guanylate cyclase, suggesting the involvement of the cGMP pathway. In all biological assays, the reference agent sodium nitroprusside was shown to be 10–1000‐fold less potent than the two metal–NONOates.
Development of Benzophenone‐Based Farnesyltransferase Inhibitors as Novel Antimalarials
Authors: Kohring Katja , Wiesner Jochen , Altenkämper Mirko , Sakowski Jacek , Silber Katrin , Hillebrecht Alexander , Haebel Peter , Dahse Hans‐Martin , Ortmann Regina , Jomaa Hassan , Klebe Gerhard , Schlitzer Martin
Published: May 2008

The development of farnesyltransferase inhibitors directed against Plasmodium falciparum is a strategy towards new drugs against malaria. Previously, we described benzophenone‐based farnesyltransferase inhibitors with high in vitro antimalarial activity but no in vivo activity. Through the introduction of a methylpiperazinyl moiety, farnesyltransferase inhibitors with in vivo antimalarial activity were obtained. Subsequently, a structure‐based design approach was chosen to further improve the antimalarial activity of this type of inhibitor. As no crystal structure of the farnesyltransferase of the target organism is available, homology modeling was used to reveal differences between the active sites of the rat/human and the P. falciparum farnesyltransferase. Based on flexible docking data, the piperazinyl moiety was replaced by a N,N,N′‐trimethylethylenediamine moiety. This resulted in an inhibitor with significantly improved in vitro and in vivo antimalarial activity. Furthermore, this inhibitor displayed a notable increase in selectivity towards malaria parasites relative to human cells.
Studies Addressing the Importance of Charge in the Binding of Fosmidomycin‐Like Molecules to Deoxyxylulosephosphate Reductoisomerase
Authors: Perruchon Johann , Ortmann Regina , Altenkämper Mirko , Silber Katrin , Wiesner Jochen , Jomaa Hassan , Klebe Gerhard , Schlitzer Martin
Published: May 2008

Fosmidomycin and its homologue FR900098 are inhibitors of 1‐deoxy‐D‐xylulose‐5‐phosphate reductoisomerase, which is part of the mevalonate‐independent isoprenoid biosynthetic pathway. Replacement of the phosphonate moiety by uncharged sulfone or sulfonamide partial structures resulted in complete loss of activity. Dropping one of the two negative charges resulted in a marked decrease in activity. Through occupation of a hydrophobic binding site, some activity could be regained, leading to compounds with micromolar activity against cultured malaria parasites.
Supratentorial ependymomas: Prognostic factors and outcome analysis in a retrospective series of 46 adult patients
Authors: Metellus Philippe , Figarella‐Branger Dominique , Guyotat Jacques , Barrie Marylin , Giorgi Roch , Jouvet Anne , Chinot Olivier ,   for the Club de Neuro‐Oncologie de la Société Française de Neurochirurgie and the Association des Neuro‐Oncologues d'Expression Française
Published: May 2008

BACKGROUND.

Ependymomas account for 2% of all intracranial tumors in adults. Supratentorial ependymomas are less common than their infratentorial counterparts. To the authors' knowledge to date, the predictive values of surgery, histology, and patient‐related prognostic factors for these tumors remain unresolved. The authors report a series of adult patients with supratentorial ependymomas to characterize the roles of surgery and histology in tumor control.

METHODS.

The authors retrospectively studied a homogenous population of 46 adult patients who had supratentorial ependymomas from 24 French neurosurgical centers between 1990 and 2004. All clinicoradiologic and follow‐up data were analyzed, and a central pathologic review was performed by 2 certified neuropathologists.

RESULTS.

The mean (±standard error) 5‐ and 10‐year overall survival rates for the entire population were 57.1% ± 8.7% and 41.8% ± 9.9%, respectively. The 5‐ and 10‐year progression‐free survival rates for the entire cohort were of 33.8% ± 8.1% and 25.4 ± 8%, respectively. On both univariate and multivariate analysis, age <55 years, greater extent of surgery, and lower histologic grade were associated with longer overall and progression‐free survival. However, longer progression‐free survival but was not considered a candidate variable for the multivariate model, because data were available for only 34 of 46 patients.

CONCLUSIONS.

In association with age and extent of surgery, histologic grade was identified as a major prognostic factor in adult supratentorial ependymomas. The application of a simple and reproducible grading scheme using objective anaplastic criteria appeared to be both useful practically and clinically applicable. The role of adjuvant radiotherapy for patients with incompletely resected, low‐grade ependymomas needs to be investigated further. Cancer 2008. © 2008 American Cancer Society.