bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical strengthening of fiberoptic microneedles using an elastomeric support
Authors: Kosoglu Mehmet A. , Hood R. Lyle , Rylander Christopher G. 
Published: April 2012

AbstractBackground and ObjectivesMicroneedles made from silica fiberoptics permit transmission and collection of light, which is an important functional advantage over metal or silicon microneedles. This added functionality may enhance or even enable new percutaneous light‐based clinical diagnostic and therapeutic procedures. Micron‐diameter fiberoptic microneedles, created from solid fibers capable of light emission and detection, are designed to penetrate several millimeters into tissue while minimizing tissue invasion and disruption. The mechanical strength (critical buckling force) of high aspect ratio (length to diameter) microneedles is a potential problem, which has motivated our invention of an elastomeric support device. In this study, we have tested our hypothesis that embedding the microneedles in an elastomeric support medium may increase microneedle critical buckling force.Materials and MethodsThe critical buckling force of silica microneedles with 55, 70, and 110 µm diameters and 3 mm lengths were measured with and without a surrounding elastomeric support (PDMS, polydimethylsiloxane). These experimental results were compared to theoretical calculations generated by the Rayleigh–Ritz buckling model. The insertion force required to penetrate ex vivo porcine skin was measured for microneedles with 55 and 70 µm diameters.ResultsUse of the PDMS support increased critical buckling force for microneedles of 55, 70, and 110 µm diameters by an average of 610%, 290%, and 33%, respectively. Theoretical calculations by the Rayleigh–Ritz model consistently overestimated the experimentally determined strengthening, but correlated highly with the greater enhancement offered to thinner microneedles. Aided by mechanical strengthening, microneedles 55 µm in diameter were able to repeatedly penetrate.ConclusionsThe critical buckling force of microneedles can be increased substantially to allow extremely high‐aspect ratio microneedles, 55–110 µm in diameter and 3 mm in length, to penetrate ex vivo porcine skin. By this strengthening method, the safety and reliability of microneedles in potential clinical applications can be considerably enhanced. Lasers Surg. Med. 44: 421–428, 2012. © 2012 Wiley Periodicals, Inc.
Magnetically Responsive Inorganic/Polydiacetylene Nanohybrids
Authors: Lee Joosub , Yoon Bora , Ham Dae‐Young , Yarimaga Oktay , Lee Chan Woo , Jaworski Justyn , Kim Jong‐Man 
Published: April 2012

AbstractA direct method for the generation of magnetically responsive conjugated polymer supramolecules is described. By immobilizing magnetite nanoparticles (MNP) on the surface of polydiacetylene (PDA) supramolecules, an inorganic/conjugated polymer hybrid system results that enables the incorporation of an important property (magnetism) to an attractive class of colorimetric PDA sensors. Benefits of this new system include: (1) ease of preparation, (2) variability in diacetylene labeling of MNPs, (3) diversity in conjugated PDA morphologies, (4) facile isolation process, and (5) immobilization of the PDA without altering the colorimetric (sensory) properties. It is demonstrated that PDA/MNP systems offer advantages in applications including film formation, separation, and sensing.
Combining Modular Ligation and Supramolecular Self‐Assembly for the Construction of Star‐Shaped Macromolecules
Authors: Altintas Ozcan , Muller Thierry , Lejeune Elise , Plietzsch Oliver , Bräse Stefan , Barner‐Kowollik Christopher 
Published: April 2012

AbstractA well‐defined random copolymer of styrene (S) and chloromethylstyrene (CMS) featuring lateral chlorine moieties with an alkyne terminal group is prepared (P(S‐co‐CMS), = 5500 Da, PDI = 1.13). The chloromethyl groups are converted into Hamilton wedge (HW) entities (P(S‐co‐HWS), = 6200 Da, PDI = 1.13). The P(S‐co‐HWS) polymer is subsequently ligated with tetrakis(4‐azidophenyl)methane to give HW‐functional star‐shaped macromolecules (P(S‐co‐HWS))4, = 25 100 Da, PDI = 1.08). Supramolecular star‐shaped copolymers are then prepared via self‐assembly between the HW‐functionalized four‐arm star‐shaped macromolecules (P(S‐co‐HW))4 and cyanuric acid (CA) end‐functionalized PS (PS–CA, = 3700 Da, PDI = 1.04), CA end‐functionalized poly(methyl methacrylate) (PMMA–CA, = 8500 Da, PDI = 1.13) and CA end‐functionalized polyethylene glycol (PEG–CA, = 1700 Da, PDI = 1.05). The self‐assembly is monitored by 1H NMR spectroscopy and light scattering analyses.
Synthesis and Thermal Behavior of Polyamide 12,T Random and Block Copolymers
Authors: Novitsky Theodore F. , Mathias Lon J. , Osborn Scott , Ayotte Roger , Manning Steven 
Published: April 2012

AbstractPA‐12,T was synthesized by melt condensation of 1,12‐diaminododecane (DA) and terephthalic acid salt and by solution polymerization of biscaprolactam terephthalamide (BCT) and DA in molten caprolactam. Stoichiometry of both methods were varied from 10 mol‐% excess terephthalic acid (or BCT) and 10 mol‐% excess DA and the impact on intrinsic viscosity, end group concentration and end group functionality was examined. PA‐12,T salt was then copolymerized with PA‐6,T salt and melting behavior was determined to examine the effect of random comonomers. Block copolymers were synthesized by anionic polymerization of PA‐6 with PA‐12,T macro‐coinitiators formed from the solution step‐growth reaction. The melting and solubility properties of the block copolymers were then correlated with the PA‐12,T block size and compared to randomly formed copolymers.
Surface Modification of Clay and Use as Stabilizer in Miniemulsion Polymerization
Authors: van den Dungen Eric T. A. , Galineau Jeremy , Hartmann Patrice C. 
Published: April 2012

AbstractPoly(styrene‐co‐butyl acrylate) latexes were successfully synthesized via Pickering miniemulsion polymerization, using modified Montmorillonite clay as the exclusive stabilizer. The latexes were stable to relatively high concentration of electrolyte due to the presence of the clay at the interface, providing both a physical barrier and electrostatic stabilization. Film formation could be done at room temperature, but the barrier properties to water and oil were poor. This was attributed to compartmentalization of the film, where the morphology of the latex particles was retained.
Characterization of Polystyrene‐block‐Polyethylene Oxide Diblock Copolymers and Blends of Homopolymers by Liquid Chromatography at Critical Conditions (LCCC)
Authors: Sinha Pritish , Grabowsky Monika , Malik Muhammad Imran , Harding Gareth William , Pasch Harald 
Published: April 2012

AbstractIn the present study, diblock copolymers of PS‐b‐PEO synthesized by sequential living anionic polymerization as well as the blends of PS, PEO homopolymers will be investigated by using liquid chromatography at critical conditions. Critical conditions will be established for the PS block of the copolymer. At these conditions, the PS block is chromatographically invisible and does not contribute to retention so the block copolymer is separated according to the block length of the PEO block. At the critical conditions of PS, it is also possible to separate the PS homopolymer formed. The critical conditions will be established in such a way that the non‐critical PEO block elutes in size exclusion chromatography (SEC) mode.
Small‐tip fast recovery imaging using non‐slice‐selective tailored tip‐up pulses and radiofrequency‐spoiling
Authors: Nielsen Jon‐Fredrik , Yoon Daehyun , Noll Douglas C. 
Published: April 2012

AbstractSmall‐tip fast recovery (STFR) imaging is a new steady‐state imaging sequence that is a potential alternative to balanced steady‐state free precession. Under ideal imaging conditions, STFR may provide comparable signal‐to‐noise ratio and image contrast as balanced steady‐state free precession, but without signal variations due to resonance offset. STFR relies on a tailored “tip‐up,” or “fast recovery,” radiofrequency pulse to align the spins with the longitudinal axis after each data readout segment. The design of the tip‐up pulse is based on the acquisition of a separate off‐resonance (B0) map. Unfortunately, the design of fast (a few ms) slice‐ or slab‐selective radiofrequency pulses that accurately tailor the excitation pattern to the local B0 inhomogeneity over the entire imaging volume remains a challenging and unsolved problem. We introduce a novel implementation of STFR imaging based on “non‐slice‐selective” tip‐up pulses, which simplifies the radiofrequency pulse design problem significantly. Out‐of‐slice magnetization pathways are suppressed using radiofrequency‐spoiling. Brain images obtained with this technique show excellent gray/white matter contrast, and point to the possibility of rapid steady‐state T2/T1‐weighted imaging with intrinsic suppression of cerebrospinal fluid, through‐plane vessel signal, and off‐resonance artifacts. In the future, we expect STFR imaging to benefit significantly from parallel excitation hardware and high‐order gradient shim systems. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Synthesis of shape memory polyurethane/clay nanocomposites and analysis of shape memory, thermal, and mechanical properties
Authors: Haghayegh M. , Mir Mohamad Sadeghi G. 
Published: April 2012

AbstractIn this study, shape memory polyurethane/clay nanocomposites were synthesized by using two‐step in situ polymerization. The effects of nanoparticle content on mechanical, thermal, and shape memory properties were studied. Soft and hard segments of polyurethanes were based on polycaprolactone (PCL) diol and 4,4′‐diphenylmethane diisocyanate/1,4‐butanediol molar ratio with 70/30, respectively. The differential scanning calorimetry, tensile test, dynamic mechanical thermal analysis, parallel plate rheometer, and X‐ray diffraction were used to evaluate the properties of the nanocomposites. To evaluate shape memory properties, a tensile device equipped with a thermal chamber was used. Glass transition temperature of soft segments has been increased by nanoclay loading. Addition of nanoclay to polyurethane matrix caused to disrupt ordering in hard domains, decrease in elongation and tensile strength. The results show that crystallinity of soft segments and dispersion of nanoparticles affect on the mechanical properties and shape memory behavior of nanocomposites, distinctly. Nanocomposite containing 1 wt% shows the best shape memory properties. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Effects of chemotherapy during pregnancy on the maternal and fetal heart
Authors: Gziri Mina Mhallem , Amant Frédéric , Debiève Frédéric , Van Calsteren Kristel , De Catte Luc , Mertens Luc 
Published: April 2012

ABSTRACTObjectiveThe co‐occurrence of cancer and pregnancy is more frequently diagnosed. The effects of cancer treatment on maternal and fetal outcomes are less well known. The cardiotoxic effects of chemotherapy are a specific concern for the mother and fetus. We wanted to review the existing literature, mainly consisting of case reports, case studies, and retrospective data.ResultsMaternal effectsOverall, the published data indicate that pregnancy is not an independent risk factor influencing cancer survival. There is no indirect evidence for an increased risk for maternal chemotherapy‐related cardiotoxicity.Fetal effectsDuring the first trimester chemotherapy needs to be avoided because of teratogenic risks. The risks of chemotherapy during the second and third trimester are more controversial. It has been associated with intrauterine growth restriction and preterm delivery in some studies, while others did not find the same effect. Cardiotoxic fetal effects have been reported despite the limited transplacental passage of chemotherapy. In most patients this was transient and long‐term data are generally reassuring.ConclusionA specific strategy for monitoring fetal and maternal chemotherapy‐induced cardiotoxicity is suggested. Prospective data are needed on the long‐term effects of chemotherapy in both mother and child. © 2012 John Wiley & Sons, Ltd.
Electron‐beam deposition of polyethylene composite coatings at various initiators and inhibitors
Authors: Liu Zhubo , Rogachev A.A. , Zhou Bing , Yarmolenko M.A. , Rogachev A.V. , Gorbachev D.L. , Jiang Xiaohong 
Published: April 2012

AbstractPolyethylene (PE) composite coatings were prepared on silicon substrate by electron‐beam deposition (EBD) using mixed powders of low‐density polyethylene and various dopants (i.e., initiator and inhibitor) as evaporated target. The structural and morphological behaviors of PE composite coatings were investigated in dependence of initiator and inhibitor by attenuated total reflectance‐Fourier transform infrared spectroscopy and atomic force microscope. Free‐radical polymerization and cationic polymerization could be observed in the formation process of PE composite coatings by EBD. The initiating system of AlCl3 and benzoyl peroxide as well as the inhibiting system of diphenylamine and hydroquinone used in EBD, in comparison with conventional synthesis methods, exhibited different effect on reaction mechanism of PE composite coatings. These results might contribute to the synthesis of polymer coatings with expectant molecule structure and controllable surface morphology. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers
Detecting impact toughness of polypropylene/poly(ethylene‐co‐octene) blends with various morphologies induced via chaotic and shear mixing
Authors: Li Ke , Huang Han‐Xiong 
Published: April 2012

AbstractBoth 80/20 and 60/40 polypropylene/poly(ethylene‐co‐octene) (PP/POE) blend samples were collected from four positions along a single‐screw extruder, which can induce chaotic and shear mixing, respectively. Results indicated that a wide range of impact strengths was obtained as the formation of series of phase morphologies. For the 80/20 blends, the impact strength increased gradually along the extruder with shear mixing due to gradual decrease of both diameter and size distribution coefficient of droplets. Whereas the impact strengths reached the highest value at about 2/3 length of the whole screw with chaotic mixing as the formation of lamellas, then decreased as their breakup. For the 60/40 blends, the impact strength reached the highest value as the formation of the thick fibrils with shear mixing; whereas the impact strength became higher at about 2/3 length of the whole screw as the formation of thin fibrils and the highest (69 times of that of pure PP) at the end of the screw due to the formation of cocontinuous structure with chaotic mixing. Observing the fractured surface of the tested sample with cocontinuous structure revealed that a distinct deformation of the PP matrix was induced by the shear yielding during impact testing. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers
An analysis of unsupported triple and quadruple metal–metal bonds between two homonuclear group 6 transition elements based on the combined natural orbitals for chemical valence and extended transition state method
Authors: Ndambuki Sylvester , Ziegler Tom 
Published: April 2012

AbstractWe have applied a newly developed energy and density decomposition scheme to the study of unsupported multiple metal–metal bonds between two Group 6D transition elements. The new scheme combines the extended transition state (ETS) energy decomposition method (Ziegler and Rauk, Theor. Chim. Acta 1977, 46, 1) with the natural orbitals for chemical valence (NOCV) density decomposition theory (Michalak et al., J. Phys. Chem. A 2008, 112, 1933) within a single framework. The ETS–NOCV scheme is here applied to the quadruply metal–metal bonded complexes L2L′2MML2L′2(1σ2π4δ2) and L3MML3with a metal triple bond(1σ2π4). © 2012 Wiley Periodicals, Inc.
Local stability analysis and domain of attraction estimation for a class of uncertain nonlinear discrete‐time systems
Authors: Coutinho Daniel , de Souza Carlos E. 
Published: April 2012

SUMMARYThis paper proposes a linear matrix inequality based method for the estimation of domain of attraction for a class of discrete‐time nonlinear systems subject to uncertain constant parameters. Recursive algebraic representations of the system dynamics and of the Lyapunov stability conditions are applied to obtain convex conditions which guarantee the system robust local stability while providing an estimate of the domain of attraction. A large class of discrete‐time nonlinear systems and of Lyapunov functions can be embedded in the proposed methodology including the whole class of regular rational functions of the system state variable and uncertain parameters. Numerical examples illustrate the application of the proposed method. Copyright © 2012 John Wiley & Sons, Ltd.
Impaired Osteoblastogenesis in a Murine Model of Dominant Osteogenesis Imperfecta: A New Target for Osteogenesis Imperfecta Pharmacological Therapy
Authors: Gioia Roberta , Panaroni Cristina , Besio Roberta , Palladini Giovanni , Merlini Giampaolo , Giansanti Vincenzo , Scovassi Ivana A. , Villani Simona , Villa Isabella , Villa Anna , Vezzoni Paolo , Tenni Ruggero , Rossi Antonio , Marini Joan C. , Forlino Antonella 
Published: April 2012

Abstract
The molecular basis underlying the clinical phenotype in bone diseases is customarily associated with abnormal extracellular matrix structure and/or properties. More recently, cellular malfunction has been identified as a concomitant causative factor and increased attention has focused on stem cells differentiation. Classic osteogenesis imperfecta (OI) is a prototype for heritable bone dysplasias: it has dominant genetic transmission and is caused by mutations in the genes coding for collagen I, the most abundant protein in bone. Using the Brtl mouse, a well-characterized knockin model for moderately severe dominant OI, we demonstrated an impairment in the differentiation of bone marrow progenitor cells toward osteoblasts. In mutant mesenchymal stem cells (MSCs), the expression of early (Runx2 and Sp7) and late (Col1a1 and Ibsp) osteoblastic markers was significantly reduced with respect to wild type (WT). Conversely, mutant MSCs generated more colony-forming unit-adipocytes compared to WT, with more adipocytes per colony, and increased number and size of triglyceride drops per cell. Autophagy upregulation was also demonstrated in mutant adult MSCs differentiating toward osteogenic lineage as consequence of endoplasmic reticulum stress due to mutant collagen retention. Treatment of the Brtl mice with the proteasome inhibitor Bortezomib ameliorated both osteoblast differentiation in vitro and bone properties in vivo as demonstrated by colony-forming unit-osteoblasts assay and peripheral quantitative computed tomography analysis on long bones, respectively. This is the first report of impaired MSC differentiation to osteoblasts in OI, and it identifies a new potential target for the pharmacological treatment of the disorder.
Endocrine Surgeon‐Performed US Guided Thyroid FNAC is Accurate and Efficient
Authors: Al‐azawi Dhafir , Mann G. Bruce , Judson Rodney T. , Miller Julie A. 
Published: April 2012

AbstractBackgroundUltrasound guided fine needle aspiration cytology (US‐FNAC) is a key diagnostic technique used to assess thyroid nodules. This procedure has been the domain of radiologists, but it is increasingly performed by endocrine surgeons. In the present study we aimed to assess the accuracy and clinical efficiency of US‐FNAC performed by endocrine surgeons.Patients and MethodsThis study was a retrospective review of consecutive patients in a 3‐year period who underwent US‐FNAC performed by endocrine surgeons and radiologists. Medical records, cytology results, and surgical pathology results were collected and analyzed.ResultsA total of 576 US‐FNAC were performed on 402 patients during the study period. The endocrine surgeons and radiologists performed 299 and 277 US‐FNAC, respectively. The FNAC inadequacy rate was 5.3 % for the endocrine surgeons and 9.3 % for the radiologists (p = 0.05). For thyroid cancer, the sensitivity, specificity, and false negatives of the US‐FNAC for the endocrine surgeons was 87 %, 98 %, and 3 %, respectively while that for the radiologists was 88 %, 95 %, and 3.5 %, respectively. Patients with thyroid cancer had a shorter time to surgery in the endocrine surgeons’ group (mean 15.3 days) compared to the radiologists’ group (mean: 53.3 days; p = 0.01).ConclusionsUS‐FNAC performed by an experienced endocrine surgeon is accurate and allows efficient surgical management for patients with thyroid cancer.
Improved trehalose production from biodiesel waste using parent and osmotically sensitive mutant of Propionibacterium freudenreichii subsp. shermanii under aerobic conditions
Authors: Ruhal Rohit , Choudhury Bijan 
Published: April 2012

Abstract
Trehalose is an important nutraceutical of wide commercial interest in the food processing industry. Recently, crude glycerol was reported to be suitable for the production of trehalose using a food microbe, Propionibacterium freudenreichii subsp. shermanii, under static flask conditions. Similarly, enhanced trehalose yield was reported in an osmotically sensitive mutant of the same strain under anaerobic conditions. In the present study, an effort was made to achieve higher production of trehalose, propionic acid, and lactic acid using the parent and an osmotically sensitive mutant of P. freudenreichii subsp. shermanii under aeration conditions. Under aeration conditions (200 rpm in shake flasks and 30 % air saturation in a batch reactor), biomass was increased and approximately 98 % of crude glycerol was consumed. In the parent strain, a trehalose titre of 361 mg/l was achieved, whereas in the mutant strain a trehalose titre of 1.3 g/l was produced in shake flask conditions (200 rpm). In the mutant strain, propionic and lactic acid yields of 0.53 and 0.21 g/g of substrate were also achieved with crude glycerol. Similarly, in controlled batch reactor culturing conditions a final trehalose titre of approximately 1.56 g/l was achieved with the mutant strain using crude glycerol as the substrate. Enhanced production of trehalose using P. freudenreichii subsp. shermanii from waste under aeration conditions is reported here. Higher production of trehalose was not due to a higher yield of trehalose but to a higher final biomass concentration.
A 1000-yr record of environmental change in NE China indicated by diatom assemblages from maar lake Erlongwan
Authors: Wang Luo , Rioual Patrick , Panizzo Virginia N. , Lu Houyuan , Gu Zhaoyan , Chu Guoqiang , Yang Deguang , Han Jingtai , Liu Jiaqi , Mackay Anson W. 
Published: April 2012

AbstractPast environmental changes based on diatom relative abundances have been inferred from the maar Lake Erlongwan in northeast China. The limnology of Lake Erlongwan is affected by the strongly seasonal regional climate. The composition of diatom assemblages, in turn, responds to changes in the seasonal duration of ice cover in winter, water-column turnover in spring and autumn, and thermal stratification in summer. Statistical analysis of the sedimentary diatom assemblages reveals three significant stratigraphic zones over the past 1000 yr. The highest abundance of the planktonic speciesDiscostellaspecies occurs between AD 1050 and 1400 and suggests an annual ice-free period of long duration and well-developed summer stratification of the water column. This planktonic diatom peak between ca. AD 1150 and 1200 suggests that this period was the warmest over the past 1000 yr. The interval between AD 1400 and 1800 is marked by a decline in planktonic diatoms and suggests shorter duration of the ice-free season, weaker water stratification and possibly generally cold conditions. After AD 1800 relative abundances of planktonic diatoms, includingPuncticulata praetermissaandAsterionella formosa, increase again, which indicates lengthening of the duration of the annual ice-free period and a stronger overturn of the water column. All these data imply that the pattern of the seasons is different between the MWP and the 20th century.