bluuebunny/crossref_metadata_2025 huggingface dataset:
Intensity modulated radiation therapy provides excellent local control in high‐risk abdominal neuroblastoma
Authors: Pai Panandiker Atmaram S. , Beltran Chris , Billups Catherine A. , McGregor Lisa M. , Furman Wayne L. , Davidoff Andrew M.
Published: September 2012

Background

Locoregional failure is a significant concern in patients with high‐risk abdominal neuroblastoma (NB) receiving radiotherapy. Locoregional control outcomes were studied in children with NB receiving intensity modulated radiotherapy (IMRT).

Procedure

Twenty children (11 females, 9 males) with NB (median age at diagnosis 3.4 years) receiving IMRT were analyzed for locoregional failure, outcomes, and toxicities. IMRT doses were 23.4 Gy (n = 12), 30 Gy (n = 1), 30.6 Gy (n = 5), and 36.0 Gy (n = 2) based on extent of resection. Five patients had tumors with MYCN amplification, and 19 had metastatic disease. All patients were treated consistently using reproducible immobilization techniques; physiological motion was assessed by 4D‐CT, and target localization by cone‐beam computed tomography. ICRU 62 volumetric conventions were employed based on institutional data for pediatric target volume and organ motion.

Results

No patient developed primary site infield or locoregional failure at a median follow‐up of 2.2 years. Distant failure (median time to distant failure 1.6 years) occurred in the brain, lungs, or skeletal sites in eight patients, five of whom died. The 2‐year event‐free survival was 58.5 ± 13.3% and cumulative incidence of local and distant failures was 0% and 41.5 ± 11.9%, respectively. Asymptomatic loose stool during RT occurred in nearly all patients, but required no intervention.

Conclusions

IMRT is feasible, safe in the short term, and yields excellent locoregional control. Despite subtotal resection in some cases, locoregional control appeared to be increased by conformal radiotherapy with ICRU 62‐compliant volumes. Dose escalation beyond 30.6 Gy may be unnecessary with improved target volume coverage. Pediatr Blood Cancer 2013; 60: 761–765. © 2012 Wiley Periodicals, Inc.
The thirteenth international childhood acute lymphoblastic leukemia workshop report: La Jolla, CA, USA, December 7–9, 2011
Authors: Hunger Stephen P. , Baruchel Andre , Biondi Andrea , Evans William E. , Jeha Sima , Loh Mignon , Moericke Anja , Pieters Rob , Relling Mary V. , Schmiegelow Kjeld , Schrappe Martin , Silverman Lewis B. , Stanulla Martin , Valsecchi Maria Grazia , Vora Ajay , Pui Ching‐Hon
Published: September 2012

XXX. Pediatr Blood Cancer
Intra‐arterial chemotherapy is more effective than sequential periocular and intravenous chemotherapy as salvage treatment for relapsed retinoblastoma
Authors: Schaiquevich Paula , Ceciliano Alejandro , Millan Natalia , Taich Paula , Villasante Francisco , Fandino Adriana C. , Dominguez Julieta , Chantada Guillermo L.
Published: September 2012

Background

Treatment of eyes with retinoblastoma failing systemic chemoreduction and external beam radiotherapy is seldom efficacious. This study compares the efficacy and toxicity of intra‐arterial ophthalmic artery chemotherapy (IAO) to our historical cohort of sequential periocular and systemic chemotherapy in such patients.

Patients and Methods

Eighteen eyes (15 consecutive patients) were retrospectively evaluated. Eight eyes received IAO for a median of four cycles (range: 2–9) including melphalan alone (n = 3) or after topotecan and carboplatin (n = 4) or topotecan and carboplatin without melphalan (n = 1). Ten eyes received a median of two cycles (range: 1–3) of periocular topotecan (n = 9) or carboplatin (n = 1) followed by intravenous topotecan and cyclophosphamide in three patients if at least stable disease was achieved. Both groups were comparable for disease extension and prior therapy.

Results

No extraocular dissemination or second malignancy occurred and all patients are alive. The probability of enucleation‐free eye survival at 12 months was 0.87 (95% CI: 0.42–0.97) for the IAO group, compared to 0.1 (95% CI: 0.06–0.35) for the periocular group (P < 0.01). Ocular toxicity was mild and similar in both groups (mostly mild orbital edema). Systemic toxicity was low for IAO and periocular injection, but children who received sequentially intravenous chemotherapy (n = 12 cycles) had five episodes of grade 4 neutropenia, three of which resulted in hospitalizations. No case in the IAO group presented these complications.

Conclusions

IAO is significantly superior to sequential periocular‐intravenous topotecan‐containing regimens in eyes with relapsed intraocular retinoblastoma with a more favorable toxicity profile. Pediatr Blood Cancer 2013; 60: 766–770. © 2012 Wiley Periodicals, Inc.
Race matters: Perceptions of race and racism in a sickle cell center
Authors: Nelson Stephen C. , Hackman Heather W.
Published: September 2012

Background

Health care disparities based on race have been reported in the management of many diseases. Our goal was to identify perceptions of race and racism among both staff and patients/families with particular attention to provider attitudes as a potential contributor to racial healthcare disparities.

Procedure

A confidential survey addressing issues of race and health care was given to all patients with sickle cell disease and their families upon arrival to clinic. The survey was made available online to all staff in the hematology/oncology program. Free text comments were obtained.

Results

We received completed surveys from 112 patients/families. Surveys were completed by 135 of 158 staff members (85% return rate). The majority (92.6%) of patients/families identified as black, while 94.1% of staff identified as white (P < 0.001). More patients/families felt that race affects the quality of health care for sickle cell patients (50% vs. 31.6%, P = 0.003). More staff perceived unequal treatment of patients, especially in the inpatient setting (20.9% vs. 10.9%, P = 0.03).

Conclusions

Provider attitudes contribute to continued racial health care disparities. We propose training health care providers on issues of race and racism. Training should provide critical thinking tools for improving medical providers' comfort and skills in caring for patients who are of a different race than their own. Pediatr Blood Cancer 2013; 60: 451–454. © 2012 Wiley Periodicals, Inc.
Experimental study of preform reheat temperature in two‐stage injection stretch blow molding
Authors: Demirel B. , Daver F.
Published: September 2012

Plastic bottles used for carbonated soft drink (CSD) packages are most commonly made from poly(ethylene terephthalate) (PET) by injection stretch blow molding (ISBM). The required bottle performance criteria vary with its application but typically include top‐load strength, burst strength, optical clarity, thermal stability, and barrier properties. An experimental study of the preform reheat temperature was carried out for a 1.5‐l PET bottle produced by a two‐stage ISBM machine. The overall temperature of the preform was changed by controlling the reheat temperature of the preform; all the other process variables and preform dimensions were kept constant. Performance of the PET bottles for differing preform reheat temperatures was measured experimentally in terms of top‐load strength, burst pressure resistance, environmental stress cracking resistance (ESCR), and thermal stability. It was observed that the ESCR values and the burst strength decreased with the increasing reheat temperature, whereas the top‐load strength increased. Thermal stability tests confirmed that high‐preform reheat temperatures had a detrimental effect on the self‐standing feature of the bottles. Decreasing the reheat temperature as low as possible, while maintaining a certain preform temperature profile, ensured high ESCR and burst strength values and prevented the concaveness at the bottom of the bottle. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Study of morphology, mechanical properties, and thermal behavior of green aliphatic–aromatic copolyester/bamboo flour composites
Authors: Adhikari Rameshwar , Bhandari Netra Lal , Causin Valerio , Le Hai H. , Radusch Hans‐Joachim , Michler Goerg H. , Saiter Jean Marc
Published: September 2012

Aiming at development of completely biodegradable composite materials based on locally available low‐cost bamboo flour (BF) as filler, structure properties correlations in aliphatic–aromatic copolyester/BF composites fabricated by melt mixing have been studied by means of different techniques such as electron microscopy, X‐ray diffraction, tensile testing, and thermogravimetric analysis (TGA). It has been demonstrated that the BF can be successfully incorporated homogeneously into the biodegradable polymeric matrix up to high content. The filler weakly adheres to the matrix as demonstrated by the pulling up of bamboo fibers on the electron micrographs and further attested by TGA. At high filler concentration, the polymer acts merely as binding material. The semicrystalline framework of the matrix polymer is hindered by the presence of the fibers, the structural changes being more pronounced at the surfaces than in the bulk, which indicates preferential segregation of the fibers toward the specimen surface. This opens new possibilities for a more detailed engineering of materials surfaces. The mechanical properties of the composites are suited for low‐load‐bearing applications. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers
Dielectric and mechanical properties of natural nanofibers‐reinforced ethylene propylene diene rubber: Carrot foliage and corn gluten
Authors: Rozik Nehad N. , Abd‐El Messieh Salwa L. , Yaseen Attia A. , Shouk Abd‐El‐Hafiz A.
Published: September 2012

A study has been carried out to investigate the dielectric and mechanical properties of composites based on reinforcing carrot foliage (CF) and corn gluten meal (CGM) as by‐products of food processing units into ethylene propylene diene rubber matrix. Transmission electron microscope micrographs indicate that both types of fillers are in the nanoscale. The permittivity ε′ and dielectric loss ε″ were measured in the frequency domain and at room temperature ∼ 25°C. The increase in ε′ and ε″ by increasing filler content is due to its reinforcing nature which was found to be more pronounced in case of CF than CGM. The mechanical properties are found to increase in the same manner. The values obtained for ε′ and ε″recommend such composites to be used in the electrical insulation purposes. The analysis of composite morphology indicated that at low concentration both types of fillers are fine distributed in the EPDM matrix, whereas at higher filler loading aggregation of filler is clearly appeared. The composites under investigation are found to be highly thermal aging resistant as both electrical and mechanical properties are slightly affected by such aging. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Contribution of organomodified clay on hybrid microstructures and properties of epoxidized natural rubber‐based nanocomposites
Authors: Chattopadhyay Pijush Kanti , Praveen Srinivasan , Chandra Das Narayan , Chattopadhyay Santanu
Published: September 2012

Influence of organic modifying agent of clay on dispersion, distribution, hybrid microstructure formation, and associated performance properties of epoxidized natural rubber‐based composites was evaluated. Binary and ternary composites of carbon black (CB) and two organomodified layered silicates (i.e., nanomer I30E and Cloisite 30B) were prepared and characterized based on small angle X‐ray scattering, transmission electron microscopy, hydrodynamic swelling, tensile measurement, and dynamic mechanical analyses. Greater extent of exfoliation and “nanounit” formation was noted in ternary composites containing nanomer I30E, which was reflected in higher interfacial roughness (ds = 2.82) and lower radius of gyration (Rg = 205 Å). Morphological observations suggested higher nanomer I30E–CB interactions than that of Cloisite 30B–CB. The interplatelet distance in Cloisite 30B (d = 1.83 nm) stacks was lower than that of nanomer I30E (d = 2.26 nm). These two factors jointly contributed in higher breakdown of nanomer I30E stacks by CB than that of Cloisite 30B stacks. Greater exfoliation and nanounit formation in I30E–CB‐filled nanocomposite was also reflected in increased degree of crosslinking (n = 20 × 10−5%), tensile modulus/strength, half height width of damping peak (20.3°C), and filler effectiveness (C = 0.33). POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Time‐dependent response of polypropylene/clay nanocomposites under tension and retraction
Authors: Drozdov Aleksey D. , Christiansen Jesper deC.
Published: September 2012

Observations are reported in relaxation tests under tension and retraction on polypropylene/clay nanocomposites with various contents of filler. A two‐phase constitutive model is developed in cyclic viscoelasticity and viscoplasticity of nanocomposites. Adjustable parameters in the stress–strain relations are found by fitting the observations. Ability of the constitutive equations to describe characteristic features of the time‐dependent behavior of nanocomposites under cyclic deformation is confirmed by numerical simulation. POLYM. ENG. SCI., 2013 © 2012 Society of Plastics Engineers
Synthesis and characterization of copolymer grafted magnetic nanoparticles via surface‐initiated nitroxide‐mediated radical polymerization
Authors: Chen Fang , Cai Zhengwang , Huang Yong , Luo Wenqian , Chen Jiucun
Published: September 2012

“Grafting from” surface‐initiated nitroxide‐mediated radical polymerization (SI‐NMRP) techniques were used to synthesize poly[styrene‐co‐(maleic anhydride)] copolymer brushes from the Fe3O4 surfaces. Well‐defined polymer chains were grown from the Fe3O4 surfaces to yield particles with a Fe3O4 core and a polymer outer layer. The observed narrow molecular weight distributions (Mw/Mn), linear kinetic plots and linear plots of molecular weight (Mn) versus conversion for the free polymer indicated that the chain growth from the Fe3O4 surface was a controlled process by adding an excess of 2,2,6,6‐tetramethylpiperidinyloxy (TEMPO). The modified nanoparticles were subjected to detailed characterization using XRD, TEM, FT‐IR, and TGA. The analyses of vibration sample magnetometer (VSM) verified that the nanoparticles owned good magnetic property. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Fabrication and characterization of boron doped yttria‐stabilized zirconia nanofibers
Authors: Tunç Tuncay , Uslu İbrahim
Published: September 2012

Boron doped and undoped poly(vinyl) alcohol/zirconium‐yttrium acetate (PVA/Zr‐Y) nanofibers were prepared by electrospinning using PVA as a precursor. The effect of boron doping was investigated in terms of solution properties, morphological changes and thermal properties. The effect of boron doping on calcined yttria stabilized zirconia (YSZ) fibers was evaluated by X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy analysis. XRD analysis revealed varying amounts of monoclinic and tetragonal zirconia present in the undoped fibers calcined at 800°C. The average crystallite sizes of the undoped YSZ were increased from 9.28 to 22.79 nm with calcining temperature increasing from 250 to 800°C. The crystallite size was enhanced with boron doping. The systematic evolution of morphological features in the spun and the processed fibers were employed by scanning electron microscopy. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Mechanical, thermal, barrier, and rheological properties of poly(ether‐block‐amide) elastomer/organoclay nanocomposite prepared by melt blending
Authors: Choi Myung‐Chan , Jung Ji‐Yoen , Yeom Hyun‐Sik , Chang Young‐Wook
Published: September 2012

Polyether block amide (PEBA) elastomer‐organoclay nanocomposites were prepared by a melt mixing technique. The X‐ray diffraction and transmission electron microscope analysis indicated that the nanocomposite formed a partially exfoliated nanostructure in which the organoclay was dispersed uniformly throughout the matrix at the nanometer scale. The effect of organoclay on the melting temperature (Tm), glass transition temperature (Tg), crystallization temperature (Tc), and heat of fusion (ΔHm) of the PEBA was determined by differential scanning calorimetry. Enhanced mechanical properties of the nanocomposites were observed from tensile and dynamic mechanical analysis. Thermal gravimetric analysis showed that the clay nanoparticles caused an increase in the thermal stability of the PEBA. Measurement of oxygen permeability and the degree of swelling in ASTM #3 oil indicated that the gas barrier properties and solvent resistance were greatly improved by the clay nanoparticles. Melt rheological studies revealed that the nanocomposites exhibited strong shear thinning behavior and a percolated network of the clay particles was formed. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
The Role of Relationships in Understanding the Alexithymia–Depression Link
Authors: Foran Heather M. , O'Leary K. Daniel
Published: September 2012

Alexithymia is associated with increased depressive symptoms in both clinical and community samples. One way that alexithymia may lead to depression is through its impact on interpersonal relationships. Individuals with alexithymia report lower perceived social support, intimacy, and relationship satisfaction. Furthermore, poor relationship functioning is a clear risk factor for depressive symptoms. Given the established alexithymia–depression link and marital dysfunction–depression link, a logical next step is to examine whether relationship dysfunction (low social support, intimacy, negative relationship behaviours, and relationship dissatisfaction) mediates the association between alexithymia and depressive symptoms. The hypothesized mediation model was assessed in a sample of 104 community couples with two analytical approaches—first with cross–sectional measures using path analysis and second with daily diary measures collected over a seven–day period using a multilevel modelling approach. Poor relationship functioning mediated the association between alexithymia and depressed mood in the daily diary data and partially mediated that association with the cross–sectional measures. These results identify alexithymia as an important variable in understanding the marital functioning–depression association, and this finding has implications for treatment. Copyright © 2012 European Association of Personality Psychology
Deciphering Subjective Trajectories for Life Satisfaction Using Self–Versus–Normative Other Discrepancies, Self–Esteem and Hope
Authors: Choma Becky L. , Busseri Michael A. , Sadava Stan W.
Published: September 2012

Drawing on temporal and social comparison perspectives, we examined sources of the widespread belief that life gets better and better over time by determining how young adults evaluate their past, present and anticipated future life satisfaction (LS) relative to beliefs about normative others. We assessed whether patterns of subjective LS trajectories based on self–versus–normative other discrepancies varied as a function of self–esteem and whether such patterns were accounted for by hope, encompassing goal–related cognitions and motivations. University participants (n = 394) completed measures of their own and normative others’ past, present and anticipated future LS, as well as self–esteem and hope scales. Results from latent growth curve analyses demonstrated that high–self–esteem and low–self–esteem individuals perceived normative others’ LS as progressing on a similar upward subjective temporal trajectory; however, high–self–esteem individuals perceived self–improvement from past to present LS and self–consistency from present to future LS relative to others. Low–self–esteem individuals perceived self–consistency from past to present LS and self–improvement from present to future LS relative to others. These associations were accounted for by hope. This research highlights the utility of combining temporal and social comparison perspectives for understanding how people envision their LS unfolding over time. Copyright © 2012 John Wiley & Sons, Ltd.
Supramolecular structure and anomer‐selective formation of polyglucuronic acid
Authors: Stetco I. Alina , Merschrod S Erika F
Published: September 2012

Polyglucuronic acids provide a biocompatible matrix for industries ranging from pharmaceuticals to agriculture. Here we provide a method for selectively producing α‐polyglucuronic acid, a simple alternative to the oxidation of cellulose or amylose with 2,2,6,6‐tetramethylpiperidine‐1‐oxyl radical (TEMPO) or isolation from bacterial cultures. Atomic force micrographs show the pH‐dependent formation and persistence of polyglucuronic acid fibrils, while NMR studies demonstrate the selectivity of the glycosidic linkage. By controlling pH, oligoglucuronate chains are created, with both NMR and AFM data showing the preservation of this linkage in basic medium after formation under acid. Clear evidence for the formation of the C–O–C glycosidic bond comes from peaks in the 13C NMR spectra, revealing a linkage through the anomeric carbon atom and also a linkage with a ring carbon atom.
Preparation of O‐diallylammonium chitosan with antibacterial activity and cytocompatibility
Authors: Jou Chi‐Hsiung , Yang Ming‐Chien , Suen Maw‐Cherng , Yen Chien‐Kuo , Hung Chia‐Chun , Hwang Mou‐Chuan
Published: September 2012

In this study, a derivative of chitosan, O‐hydroxy‐2,3‐propyl‐N‐methyl‐N,N‐diallylammonium chitosan methyl sulfate (O‐MDAACS), was synthesized by reacting chitosan with methyl diallyl ammonium. The O‐MDAACS was confirmed by Fourier transform infrared spectroscopy and 1H NMR. Characterization was conducted including X‐ray diffraction, differential scanning calorimetry and thermogravimetry. The antibacterial activities of O‐MDAACS against Staphylococcus aureus and Klebsiella pneumoniae were evaluated. The minimum inhibitory concentrations on O‐MDAACS were 3.7% and 23% of those on chitosan against S. aureus and K. pneumonia, respectively. The minimum bactericidal concentrations on O‐MDAACS were 7% and 36% of those on chitosan against S. aureus and K. pneumonia, respectively. Thus the antibacterial activity of O‐MDAACS was higher than that of chitosan. The cytocompatibility was evaluated in vitro with L929 fibroblasts. The results showed that after 72 h incubation the cell viability on O‐MDAACS was about 12% and 59% higher than those on chitosan and on control, respectively. © 2012 Society of Chemical Industry
Grafting of titanium dioxide microspheres with a temperature‐responsive polymer via surface‐initiated atom transfer radical polymerization without the use of silane coupling agents
Authors: Smirnov Eugene A , Meledina Maria A , Garshev Alexey V , Chelpanov Vitaly I , Frost Sven , Wieneke Jan U , Ulbricht Mathias
Published: September 2012

Titania microspheres with narrow size distribution and diameters of about 1 µm were prepared and subsequently functionalized using surface‐initiated atom transfer radical polymerization (ATRP) of N‐isopropylacrylamide. The ATRP initiator was immobilized on the particle surface via acylation of surface hydroxyl groups with α‐bromoisobutyryl bromide. Subsequently, an established ATRP reaction system was used for the preparation of titania surface‐grafted poly(N‐isopropylacrylamide) (PNiPAAm). Characterization was performed with electron microscopies, X‐ray diffraction, infrared spectroscopy and dynamic light scattering. It was found that the particle size in aqueous dispersions changed reversibly with temperature as expected for a shell of PNiPAAm, a polymer with a lower critical solution temperature at 32 °C. This confirmed the successful preparation of functional, stimuli‐responsive TiO2 microparticles via a straightforward controlled surface‐initiated polymerization method.
Morphology and property changes of immiscible polycarbonate/poly(L‐lactide) blends induced by carbon nanotubes
Authors: Wang Yong‐hong , Shi Yun‐yun , Dai Jian , Yang Jing‐hui , Huang Ting , Zhang Nan , Peng Ya , Wang Yong
Published: September 2012

Blends of polycarbonate (PC)/poly(l‐lactide) (PLLA) have great potential in applications ranging from packaging materials to consumer electronics. However, research into these blends is relatively limited compared with that into other polyesters. In this work, different contents of functionalized multiwalled carbon nanotubes (FMWCNTs) were introduced into PC/PLLA blends. The crystallization and melting behaviors of the nanocomposites were investigated using differential scanning calorimetry. The morphology of the nanocomposites and the dispersion states of the FMWCNTs were investigated using scanning electron microscopy, transmission electron microscopy and rheological measurements. The results showed that all samples were in the amorphous state during the injection‐molding process. Although the co‐continuous morphology features of samples was not changed, the presence of the FMWCNTs noticeably induced an increase of phase domains of PC, which was suggested to be the result of the formation of a percolated FMWCNT network structure. The electrical resistivity of the nanocomposites was greatly reduced when the content of FMWCNTs was increased to 2 wt%. The determination of mechanical properties showed that the addition of FMWCNTs facilitated an improvement of the fracture resistance. Another exciting aspect of this research was that the hydrolytic degradation ability of the blends was further improved by adding the FMWCNTs.
‘Edge‐light’: combination of sensitive crack detection and luminescence measurements
Authors: Ortner A. , Gräff O. , Stelzl M. , Macherey F. , Neubecker R.
Published: September 2012

We present a measurement technique that we call ‘edge‐light’, which allows a very sensitive detection of cracks in solar wafers and cells. For polycrystalline material, we found to be able to detect much smaller cracks than possible with conventional equipment. The technique is based on dark‐field illumination with the illuminating light entering the wafer (or the cell) from the edges and being kept inside the wafer by total internal reflection. As detector, an infrared line‐scan camera is used, giving high resolution images. In this configuration, even small cracks appear with high contrast, whereas the grain structure is not visible. In the same setup, photoluminescence or electroluminescence can be recorded in the same run in order to gain information on electronic properties. For the case of photoluminescence, only the scan line needs to be irradiated by the optical excitation source. Consequently, the necessary optical power can be lower and/or exposure times can be shorter. The combination of several measurement channels (crack detection, luminescence) with different light/excitation sources and a single camera is achieved by a special application software for an field programmable gate array (FPGA) frame grabber. The integration of the two measurements principles in a single setup allows simultaneous determination of mechanical stability and electronic quality properties. The setup was proven to work under inline conditions. Copyright © 2012 John Wiley & Sons, Ltd.
A comparative analysis of computational approaches to relative protein quantification using peptide peak intensities in label‐free LC‐MS proteomics experiments
Authors: Matzke Melissa M. , Brown Joseph N. , Gritsenko Marina A. , Metz Thomas O. , Pounds Joel G. , Rodland Karin D. , Shukla Anil K. , Smith Richard D. , Waters Katrina M. , McDermott Jason E. , Webb‐Robertson Bobbie‐Jo
Published: September 2012

Liquid chromatography coupled with mass spectrometry (LC‐MS) is widely used to identify and quantify peptides in complex biological samples. In particular, label‐free shotgun proteomics is highly effective for the identification of peptides and subsequently obtaining a global protein profile of a sample. As a result, this approach is widely used for discovery studies. Typically, the objective of these discovery studies is to identify proteins that are affected by some condition of interest (e.g. disease, exposure). However, for complex biological samples, label‐free LC‐MS proteomics experiments measure peptides and do not directly yield protein quantities. Thus, protein quantification must be inferred from one or more measured peptides. In recent years, many computational approaches to relative protein quantification of label‐free LC‐MS data have been published. In this review, we examine the most commonly employed quantification approaches to relative protein abundance from peak intensity values, evaluate their individual merits, and discuss challenges in the use of the various computational approaches.
Mouse models of growth hormone action and aging: A proteomic perspective
Authors: Ding Juan , Sackmann‐Sala Lucila , Kopchick John J.
Published: September 2012

Growth hormone (GH) is a protein secreted by the anterior pituitary and circulates throughout the body to exert important actions on growth and metabolism.GHstimulates the secretion of insulin‐like growth factor‐I(IGF‐I) that mediates some of the growth promoting actions ofGH. TheGH/IGF‐Iaxis has recently been recognized as important in terms of longevity in organisms ranging fromCaenorhabditis elegansto mice. For example,GHtransgenic mice possess short lifespans whileGHreceptor null (GHR‒/‒) mice have extended longevity. Thus, the actions ofGH(orIGF‐I) or lack thereof impact the aging process. In this review, we summarize the proteomic analyses of plasma and white adipose tissue in these two mouse models ofGHaction, i.e.GHtransgenic andGHR‒/‒ mice. At the protein level, we wanted to establish novel plasma biomarkers ofGHaction as a function of age and to determine differences in adipose tissue depots. We have shown that these proteomic approaches have not only confirmed several known physiological actions ofGH, but also resulted in novel protein biomarkers and targets that may be indicative of the aging process and/or new functions ofGH. These results may generate new directions forGHand/or aging research.
Binding cellulose and chitosan via click chemistry: Synthesis, characterization, and formation of some hollow tubes
Authors: Peng Pai , Cao Xuefei , Peng Feng , Bian Jing , Xu Feng , Sun Runcang
Published: September 2012

A novel cellulose‐click‐chitosan polymer was prepared successfully in three steps: (1) propargyl cellulose with degrees of substitution (DS) from 0.25 to 1.24 was synthesized by etherification of bamboo Phyllostachys bambusoide cellulose with propargyl chloride in DMA/LiCl in the presence of NaH. The regioselectivity of propargylation on anhydrous glucose unit determined by GC‐MS was in the order of 2 >> 6 > 3; (2) the functional azide groups were introduced onto the chitosan chains by reacting chitosan with 4‐azidobenzoic acid in [Amim]Cl/DMF and the DS ranged from 0.02 to 0.46; (3) thus, the cellulose‐click‐chitosan polymer was obtained via click reaction, that is, the Cu(I)‐catalyzed Huisgen 1,3‐dipolar cycloaddition reaction, between the terminal alkyne groups of cellulose and the azide groups on the chitosan backbone at room temperature. The successful binding of cellulose and chitosan was confirmed and characterized by FTIR and CP/MAS 13C NMR spectroscopy. TGA analyses indicated that the cellulose‐click‐chitosan polymer had a higher thermal stability than that of cellulose and chitosan as well as cellulose–chitosan complex. More interestingly, some hollow tubes with near millimeter length were also observed by SEM. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Biodegradable poly(carbonate‐ether)s with thermoresponsive feature at body temperature
Authors: Gu Lin , Gao Yonggang , Qin Yusheng , Chen Xuesi , Wang Xianhong , Wang Fosong
Published: September 2012

Novel biodegradable poly(carbonate‐ether)s (PCEs) with lower critical solution temperature (LCST) at body temperature were synthesized by copolymerization of CO2 and ethylene oxide (EO) under double metal cyanide (DMC) catalyst. The PCEs showed carbonate unit (CU) content of 1.0–42.4 mol % and molecular weight of 2.7–247 kg/mol, which exhibited reversible thermoresponsive feature in deionized water with LCST in a broad window from 21.5 to 84.1 °C. The LCST was highly sensitive to the CU content and the molecular weight of PCEs, and it showed a linear relation with CU content for PCEs with similar molecular weight. In particular, aqueous solution of PCE with a 26.0 mol % of CU showed an LCST around 36.1 °C, which was very close to the body temperature. Interestingly, it was found that the phase transition behavior changed with PCE concentration. For PCE with Mn of 2.7 kg/mol and CU content of 30.0 mol %, the LCST increased from 21.5 to 36.7 °C when the PCE concentration changed from 10 to 1 g/L. Dynamic light scattering indicated that the phase transition was possibly due to a coil‐to‐globule transition. The thermoresponsive biodegradable PCE with LCST at body temperature is promising for biomedical applications, especially for in vivo applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Polypyrrole stretchable actuators
Authors: Zheng Wen , Alici Gursel , Clingan Philip R. , Munro Bridget J. , Spinks Geoffrey M. , Steele Julie R. , Wallace Gordon G.
Published: September 2012

Here, we report a simple way to prepare stretchable polypyrrole (PPy)‐based actuator materials that can be operated over a wide dynamic strain range and generate useable actuation displacements and pressures. The stretchable actuators were prepared as a laminated composite of PPy and a gold‐coated roughened rubber sheet. By manipulating the corrugated surface of the rubber substrate, the stretchability of PPy was greatly improved. Gold‐coated rubbers could be stretched to 30% without significant change in electrical resistance. The corrugated PPy/gold/rubber laminates successfully showed ∼1% of actuation strain even when prestretched to 24%. The actuation strains were smaller than for similar free‐standing PPy films and a detailed analysis of the effects of corrugation and of the rubber substrate are presented to predict actuation strain under various prestretch strains. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Plasma Etching of Poly(dimethylsiloxane): Roughness Formation, Mechanism, Control, and Application in the Fabrication of Microfluidic Structures
Authors: Vlachopoulou Maria‐Elena , Kokkoris George , Cardinaud Christophe , Gogolides Evangelos , Tserepi Angeliki
Published: September 2012

Etching of PDMS in SF6 plasmas is investigated as planar technology for the fabrication of microfluidic devices with simultaneous control of surface topography and wettability. Plasma conditions were optimized for high etch rate, which was achieved at high plasma powers and bias voltages, where PDMS microstructures exhibited good anisotropy. Depending on the etcher wall and the mask material, topography can be controlled from very rough to almost smooth. Independent control of the topography was achieved by treating the rough surfaces with wet etchants. Open microchannels of controlled surface roughness and wettability were fabricated. Subsequently, such microchannels were irreversibly sealed with a PDMS cover plate, for fabrication of enclosed microchannels. Plasma etching of PDMS is proven to be a reliable and indispensable method for the fabrication of microfluidic devices with desired wall roughness and wettability.

magnified image
Wood Protective Fungicidal Treatment: Quaternary Ammonium Molecules Grafting on Cellulose Assisted by Afterglows at Atmospheric Pressure
Authors: Lecoq Elodie , Desbrieres Jacques , Clement Franck , Leclaire Charlotte , Held Bernard
Published: September 2012

Wood or cellulosic materials protection against fungi is possible by binding covalent molecules as quaternary ammonium compounds (QAC) on the hydroxyl reactive groups present in cellulose. This work firstly consists in the synthesis of a specific quaternary ammonium molecule containing a long aliphatic chain and an epoxide reactive group: Glycidyldimethyldodecylammonium chloride (GDDAC). Fungicidal properties of this molecule have been proven. Secondly, afterglows issued from atmospheric pressure Dielectric Barrier Discharges (DBDs), can assist QAC grafting on cellulose. The efficiency of the reaction is improved by adding a few percentage of oxygen in nitrogen DBD. Antifungal efficiency of GDDAC grafting on wood sawdust is finally shown demonstrating the great interest of such process.

magnified image
Understanding the Synthesis of Ethylene Glycol Pulsed Plasma Discharges
Authors: Wells Gabriel Padron , Estrada‐Raygoza Isabel Cristina , Thamban P. L. Stephan , Nelson Caleb T. , Chung Chin‐Wook , Overzet Lawrence J. , Goeckner Matthew J.
Published: September 2012

In the present work, an investigation of the gas and surface phase behavior of ethylene glycol (EG) pulsed discharges is presented. Infrared and optical emission spectroscopy along with time‐resolved electron temperature (Te) and electron density (ne) measurements were employed in these pulsed EG plasmas to study the dynamics of monomer fragmentation and effective chemical feedback from boundary walls. Maximized retention of monomer functionality, (CH2CH2O)n, were seen in polymer deposits when processed at low values of average power (<20 W). This preservation of monomer functionality is attributed to the increase in effective collision time between electrons and EG molecules. Presented results correlated well with proposed ethylene glycol dissociation pathways in the pulsed discharge.

magnified image
Neutral Polymeric Bonding Agents (NPBA) and Their Use in Smokeless Composite Rocket Propellants Based on HMX‐GAP‐BuNENA
Authors: Landsem Eva , Jensen Tomas L. , Hansen Finn K. , Unneberg Erik , Kristensen Tor E.
Published: September 2012

Very few efficient bonding agents for use in solid rocket propellants with nitramine filler materials and energetic binder systems are currently available. In this work, we report the synthesis, detailed characterization, and use of neutral polymeric bonding agents (NPBA) in isocyanate‐cured and smokeless composite rocket propellants based on the nitramine octogen (HMX), the energetic binder glycidyl azide polymer (GAP), and the energetic plasticizer N‐butyl‐2‐nitratoethylnitramine (BuNENA). These polymeric bonding agents clearly influenced the viscosity of the uncured propellant mixtures and provided significantly enhanced mechanical properties to the cured propellants, even at low NPBA concentrations (down to 0.001 wt‐% of propellant). A modified NPBA more or less free of hydroxyl functionalities for interactions with isocyanate curing agent provided the same level of mechanical improvement as regular NPBA containing a substantial number of reactive hydroxyl groups. However, some degree of reactivity towards isocyanate is essential for function.
Formation and Characterization of Nano‐sized RDX Particles Produced Using the RESS‐AS Process
Authors: Essel Jonathan T. , Cortopassi Andrew C. , Kuo Kenneth K. , Leh Christopher G. , Adair James H.
Published: September 2012

It has been shown that nano‐sized particles of secondary explosives are less sensitive to impact and can alter the energetic performance of a propellant or explosive. In this work the Rapid Expansion of a Supercritical Solution into an Aqueous Solution (RESS‐AS) process was used to produce nano‐sized RDX (cyclo‐1,3,5‐trimethylene‐2,4,6‐trinitramine) particles. When a saturated supercritical carbon dioxide/RDX solution was expanded into neat water, RDX particles produced from the RESS‐AS process agglomerated quickly and coarsened through Ostwald ripening. However, if the pH level of the suspension was changed to 7, particles were metastably dispersed with a diameter of 30 nm. When the supercritical solution was expanded into air under the same pre‐expansion conditions using the similar RESS process, RDX particles were agglomerated and had an average size of approximately 100 nm. Another advantage of using a liquid receiving solution is the possibility for coating energetic particles with a thin layer of polymer. Dispersed particles were formed by coating the RDX particles with the water soluble polymers polyvinylpyrrolidone (PVP) or polyethylenimine (PEI) in the RESS‐AS process. Both PVP and PEI were used because they have an affinity to the RDX surface. Small and well‐dispersed particles were created for both cases with both PVP and PEI‐coated RDX particles shown to be stable for a year afterward. Several benefits are expected from these small polymer coated RDX particles such as decreased sensitivity, controlled reactivity, and enhanced compatibility with other binders for fabrication of bulk‐sized propellants and/or explosives.
Correlation of Structure and Sensitivity in Inorganic Azides III. A Mechanistic Interpretation of Impact Sensitivity Dependency on Non‐bonded Nitrogen to Nitrogen Distance
Authors: Cartwright Michael
Published: September 2012

Previously established correlations between impact sensitivity and minimum, non‐bonded, nitrogen to nitrogen distances in inorganic azides, imply that there must be a mechanism in operation, which can predict the non reaction of alkali metal azides and the violent decomposition of copper, silver, and lead azides. This paper examines the molecular orbitals used for bonding in the azides. The orbital energy level diagram indicates that the highest occupied molecular orbital, HOMO, are two, π type, non‐bonded orbitals, each occupied by an electron pair. The electron density lobes for these π type orbitals protrude into the space beyond both ends of the azide ion. These orbitals can overlap with ‘p’ and ‘d’ type orbitals on the metal cation, facilitating the transfer of the electron back to the metal cation; an integral part of the decomposition reaction. If an exciton is generated on the azide ion, the electron can migrate, via the extended three center MO, to the metal cation, leaving the positive hole on the terminal nitrogen atom. A similar hole on an adjacent azide, would allow the non‐bonding orbitals on each azide to interact. As the distance between neighboring azide ions decreases, it is postulated that these, non‐bonding, π type orbitals start to overlap and become bonding orbitals between adjacent azide ions. This process forms an unstable N6 moiety, which leads to the formation of three nitrogen molecules from two original azide ions. Thus, a feasible mechanism for the reaction can explain the observation that azides with non‐bonded nitrogen to nitrogen distances of >300 nm do not show impact sensitivity but, as this distance decreases below 300 nm, the sensitivity increases. The non impact sensitive azides could respond to thermal stimulus, which increases the thermal motion, thus reducing the critical nitrogen to nitrogen non‐bonded distance and reducing the energy for exciton production. Further work is required on the energy changes for such a reaction.
The binding mechanism, multiple binding modes, and allosteric regulation of Staphylococcus aureus Sortase A probed by molecular dynamics simulations
Authors: Kappel Kalli , Wereszczynski Jeff , Clubb Robert T. , McCammon J. Andrew
Published: September 2012

Sortase enzymes are vitally important for the virulence of gram‐positive bacteria as they play a key role in the attachment of surface proteins to the cell wall. These enzymes recognize a specific sorting sequence in proteins destined to be displayed on the surface of the bacteria and catalyze the transpeptidation reaction that links it to a cell wall precursor molecule. Because of their role in establishing pathogenicity, and in light of the recent rise of antibiotic‐resistant bacterial strains, sortase enzymes are novel drug targets. Here, we present a study of the prototypical sortase protein Staphylococcus aureus Sortase A (SrtA). Both conventional and accelerated molecular dynamics simulations of S. aureus SrtA in its apo state and when bound to an LPATG sorting signal (SS) were performed. Results support a binding mechanism that may be characterized as conformational selection followed by induced fit. Additionally, the SS was found to adopt multiple metastable states, thus resolving discrepancies between binding conformations in previously reported experimental structures. Finally, correlation analysis reveals that the SS actively affects allosteric pathways throughout the protein that connect the first and the second substrate binding sites, which are proposed to be located on opposing faces of the protein. Overall, these calculations shed new light on the role of dynamics in the binding mechanism and function of sortase enzymes.
The crystal structure of samarosporin I at atomic resolution
Authors: Gessmann Renate , Axford Danny , Evans Gwyndaf , Brückner Hans , Petratos Kyriacos
Published: September 2012

The atomic resolution structures of samarosporin I have been determined at 100 and 293 K. This is the first crystal structure of a natural 15‐residue peptaibol. The amino acid sequence in samarosporin I is identical to emerimicin IV and stilbellin I. Samarosporin is a peptide antibiotic produced by the ascomycetous fungus Samarospora rostrup and belongs to peptaibol subfamily 2. The structures at both temperatures are very similar to each other adopting mainly a 310‐helical and a minor fraction of α‐helical conformation. The helices are significantly bent and packed in an antiparallel fashion in the centered monoclinic lattice leaving among them an approximately 10‐Å channel extending along the crystallographic twofold axis. Only two ordered water molecules per peptide molecule were located in the channel. Comparisons have been carried out with crystal structures of subfamily 2 16‐residue peptaibols antiamoebin and cephaibols. The repercussion of the structural analysis of samarosporin on membrane function is discussed. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.
Stem cell recovering effect of copper‐free GHK in skin
Authors: Choi Hye‐Ryung , Kang Youn‐A , Ryoo Sun‐Jong , Shin Jung‐Won , Na Jung‐Im , Huh Chang‐Hun , Park Kyoung‐Chan
Published: September 2012

The peptide Gly‐His‐Lys (GHK) is a naturally occurring copper(II)‐chelating motifs in human serum and cerebrospinal fluid. In industry, GHK (with or without copper) is used to make hair and skin care products. Copper‐GHK plays a physiological role in the process of wound healing and tissue repair by stimulating collagen synthesis in fibroblasts. We also reported that copper‐GHK promotes the survival of basal stem cells in the skin. However, the effects of copper‐free GHK (GHK) have not been investigated well. In this study, the effects of GHK were studied using cultured normal human keratinocytes and skin equivalent (SE) models. In monolayer cultured keratinocytes, GHK increased the proliferation of keratinocytes. When GHK was added during the culture of SE models, the basal cells became more cuboidal than control model. In addition, there was linear and intense staining of α6 and β1 integrin along the basement membrane. The number of p63 and proliferating cell nuclear antigen positive cells was also significantly increased in GHK‐treated SEs than in control SEs. Western blot and slide culture experiment showed that GHK increased the expression of integrin by keratinocytes. All these results showed that GHK increased the stemness and proliferative potential of epidermal basal cells, which is associated with increased expression of integrin. In conclusion, copper‐free GHK showed similar effects with copper‐GHK. Thus, it can be said that copper‐free GHK can be used in industry to obtain the effects of copper‐GHK in vivo. Further study is necessary to explore the relationship between copper‐free GHK and copper‐GHK. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.