bluuebunny/crossref_metadata_2025 huggingface dataset:
Hello ADIOS: the challenges and lessons of developing leadership class I/O frameworks
Authors: Liu Qing , Logan Jeremy , Tian Yuan , Abbasi Hasan , Podhorszki Norbert , Choi Jong Youl , Klasky Scott , Tchoua Roselyne , Lofstead Jay , Oldfield Ron , Parashar Manish , Samatova Nagiza , Schwan Karsten , Shoshani Arie , Wolf Matthew , Wu Kesheng , Yu Weikuan
Published: August 2013

Applications running on leadership platforms are more and more bottlenecked by storage input/output (I/O). In an effort to combat the increasing disparity between I/O throughput and compute capability, we created Adaptable IO System (ADIOS) in 2005. Focusing on putting users first with a service oriented architecture, we combined cutting edge research into new I/O techniques with a design effort to create near optimal I/O methods. As a result, ADIOS provides the highest level of synchronous I/O performance for a number of mission critical applications at various Department of Energy Leadership Computing Facilities. Meanwhile ADIOS is leading the push for next generation techniques including staging and data processing pipelines. In this paper, we describe the startling observations we have made in the last half decade of I/O research and development, and elaborate the lessons we have learned along this journey. We also detail some of the challenges that remain as we look toward the coming Exascale era. Copyright © 2013 John Wiley & Sons, Ltd.
Homogeneous versus Heterogeneous Catalysts in Water Oxidation
Authors: Fukuzumi Shunichi , Hong Dachao
Published: August 2013

Recent developments in thermal and photochemical water oxidation by using homogeneous and heterogeneous catalysts is described together with the conversion of the homogeneous catalysts into heterogeneous catalysts during the course of water oxidation. The use of homogeneous catalysts is advantageous in the elucidation of detailed catalytic mechanisms including the detection of active intermediates for water oxidation. In contrast, heterogeneous catalysts are advantageous for practical applications, because of their high catalytic activity and the ease with which they can be separated by filtration. However, it is quite difficult to identify the active intermediates on the surfaces of heterogeneous catalysts, and therefore, the heterogeneous catalytic mechanism of water oxidation has not been clarified. Although investigations on homogeneous and heterogeneous catalysts for water oxidation have been performed rather independently, the link between homogeneous and heterogeneous catalysts is becoming more important for the development of efficient WOCs. This microreview focuses on factors to determine if the actual catalysts for water oxidation are homogeneous or heterogeneous depending on the conditions under which the catalysts are used. Ligand oxidation of homogeneous catalysts sometimes results in dissociation of the ligands to form nanoparticles, which act as much more efficient catalysts for water oxidation.
K‐Oxyma: a Strong Acylation‐Promoting, 2‐CTC Resin‐Friendly Coupling Additive
Authors: Cherkupally Prabhakar , Acosta Gerardo A. , Nieto‐Rodriguez Lidia , Spengler Jan , Rodriguez Hortensia , Khattab Sherine N. , El‐Faham Ayman , Shamis Marina , Luxembourg Yoav , Prohens Rafel , Subiros‐Funosas Ramon , Albericio Fernando
Published: August 2013

Here we present a new formulation of the recently introduced OxymaPure additive for peptide bond formation, in which the N‐hydroxylamine group is replaced by a potassium salt. The complete suppression of its acidity converts K‐Oxyma into the most suitable coupling choice when peptides are assembled on highly acid‐labile solid‐supports. The coupling efficiency and diminished prospects for epimerization are conserved relative to OxymaPure. In addition, K‐Oxyma displays excellent solubility in a variety of organic solvents and undergoes safer decomposition than classical 1‐hydroxybenzotriazole additives.
Recent advances and future prospects for increased butanol production by acetone‐butanol‐ethanol fermentation
Authors: Tashiro Yukihiro , Yoshida Tsuyoshi , Noguchi Takuya , Sonomoto Kenji
Published: August 2013

Presently, several researchers are increasingly focusing on producing butanol as the next‐generation fuel by acetone‐butanol‐ethanol (ABE) fermentation. Butanol has many superior characteristics compared to other biofuels, such as ethanol. However, its production by ABE fermentation faces the challenges of low productivity and yield because of product inhibition and heterofermentation, respectively, and thereby, high costs. Until date, molecular biological techniques and fermentation engineering methods have been applied for high butanol production. Although glucose remains the substrate of choice since traditional research, it is now necessary to substitute glucose derived from edible starch to other substrates from low‐cost feedstock, such as agricultural residue. In addition, ABE‐producing clostridia cannot directly produce butanol from lignocelluloses. Therefore, recent research is focusing on pretreatment and enzymatic saccharification of the complex molecules derived from agricultural residue for use as feedstock in butanol production. This article reviews traditional research, including the metabolism patterns and characteristics of ABE‐producing clostridia. Furthermore, this article describes developments in ABE fermentation with respect to the establishment of highly efficient butanol production processes, such as batch, fed‐batch, and continuous cultures, with the introduction of butanol removal, as well as butanol production from lignocellulosic biomasses or alternative substrates to sugars.
The stream power river incision model: evidence, theory and beyond
Authors: Lague Dimitri
Published: August 2013

The stream power incision model (SPIM) is a cornerstone of quantitative geomorphology. It states that river incision rate is the product of drainage area and channel slope raised to the power exponents m and n, respectively. It is widely used to predict patterns of deformation from channel long profile inversion or to model knickpoint migration and landscape evolution. Numerous studies have attempted to test its applicability with mixed results prompting the question of its validity. This paper synthesizes these results, highlights the SPIM deficiencies, and offers new insights into the role of incision thresholds and channel width. By reviewing quantitative data on incising rivers, I first propose six sets of field evidence that any long‐term incision model should be able to predict. This analysis highlights several inconsistencies of the standard SPIM. Next, I discuss the methods used to construct physics‐based long‐term incision laws. I demonstrate that all published incising river datasets away from knickpoints or knickzones are in a regime dominated by threshold effects requiring an explicit upscaling of flood stochasticity neglected in the standard SPIM and other incision models. Using threshold‐stochastic simulations with dynamic width, I document the existence of composite transient dynamics where knickpoint propagation locally obeys a linear SPIM (n=1) while other part of the river obey a non‐linear SPIM (n>1). The threshold‐stochastic SPIM resolves some inconsistencies of the standard SPIM and matches steady‐state field evidence when width is not sensitive to incision rate. However it fails to predict the scaling of slope with incision rate for cases where width decreases with incision rate. Recent proposed models of dynamic width cannot resolve these deficiencies. An explicit upscaling of sediment flux and threshold‐stochastic effects combined with dynamic width should take us beyond the SPIM which is shown here to have a narrow range of validity. Copyright © 2013 John Wiley & Sons, Ltd.
The geomorphological context and impact of the linear emergent macrophyte, Sparganium erectum L.: a statistical analysis of observations from British rivers
Authors: Gurnell Angela M. , O'Hare Matthew T. , O'Hare Judith M. , Scarlett Peter , Liffen Thomas M.R.
Published: August 2013

This paper explores the geomorphological context and impact of the widely‐occurring, linear emergent macrophyte, Sparganium erectum.

Forty‐seven sites across Britain were selected for field investigation, spanning the range of environmental conditions within which Sparganium erectum had been found to be present in previous analyses of national data sets. A combination of descriptive graphs and statistics, principal components analysis, and Kruskal–Wallis tests were used to explore the large multivariate data set collected at the 47 sites.

The analyses showed that Sparganium erectum is present in significant quantities in relatively narrow and shallow (< 18 m wide and < 0.9 m deep to the limit of terrestrial vegetation), low gradient (maximum 0.004) channels of varying bed sediment calibre (cobble to silt). Within these environments, S. erectum stands (features) were associated with fine sediment retention, aggradation and submerged landform construction, leading to bench development and so, potentially, to adjustments in channel form and position. Sediment retention and landform construction within S. erectum features was most strongly apparent within reaches with a relatively high S. erectum cover and the presence of large area S. erectum features. It was also associated more weakly with S. erectum features that were comprised of relatively higher densities of plants with relatively smaller inter‐plant spacing and fewer leaves. The sediment retained in S. erectum features and associated bench and bank toe deposits showed larger numbers and species of viable seeds, indicating the potential for colonization and growth of other species on S. erectum features once they aggrade above the low flow water level and are no longer a suitable habitat for S. erectum. Copyright © 2013 John Wiley & Sons, Ltd.
High Frequency Trading in the Korean Index Futures Market
Authors: Lee Eun Jung
Published: August 2013

We investigate the trading behavior of high frequency trading (HFT), the impact of HFT on market quality, its role in the price discovery process, and its profitability, using a very detailed data set of the KOSPI 200 index futures market. We find that high frequency traders (HFTs) do not provide liquidity in the futures market, nor does HFT have any role in enhancing market quality. Indeed, HFT is detrimental to the price discovery process. This finding is contrary to those in the existing literature on HFT in equity markets. We also find that profitable opportunities for HFTs are rare after transaction costs are considered, with the notable exception that foreign HFTs can earn a profit in the index futures market. © 2013 Wiley Periodicals, Inc. Jrl Fut Mark 35:31–51, 2015
The Giant Pacific Oyster (Crassostrea gigas) as a modern analog for fossil ostreoids: Isotopic (Ca, O, C) and elemental (Mg/Ca, Sr/Ca, Mn/Ca) proxies
Authors: Ullmann Clemens V. , Böhm Florian , Rickaby Rosalind E.M. , Wiechert Uwe , Korte Christoph
Published: August 2013

Modern analogs are an essential part of palaeoclimate studies, because they provide the basis for the understanding of geochemical signatures of fossils. Ostreoids are common in many sedimentary sequences and because of their fast growth, high temporal resolution sampling of past seasonal variability is possible. Here, two shell structures of modern Giant Pacific Oysters (Crassostrea gigas), the chalky substance and foliate layers, have been sampled for trace element distributions (Mg, Sr, Mn) and stable isotope variability (C, O, Ca). Oxygen isotopes exhibit a clear seasonal signature. Mean carbon isotope values of different oysters agree within 0.1‰, but ontogenic variability is complicated by shell growth patterns and potential small vital effects. The calcium isotope ratios are found to be constant throughout ontogeny within analytical precision at a value of δ44/40Ca = 0.68 ± 0.16‰ (2 sd) SRM–915a which is consistent with other bivalve species. Calcium isotope ratios in oyster shell material might thus be a possible proxy for palaeo seawater calcium isotope ratios. Element/Ca ratios are significantly higher in the chalky substance than in the foliate layers and especially high Sr/Ca and Mn/Ca ratios are observed for the first growth season of the oysters. Mg/Ca ratios in the chalky substance show a negative correlation with δ18O values, compatible with a temperature dependence, whereas this correlation is absent in the foliate layers. Seasonal changes of Sr/Ca are controlled by metabolic processes, whereas for Mn/Ca an additional environmental control is evident.
Eruptive fracture location forecasts from high‐frequency events on Piton de la Fournaise Volcano
Authors: De Barros Louis , Bean Christopher J. , Zecevic Megan , Brenguier Florent , Peltier Aline
Published: August 2013

Piton de la Fournaise (La Réunion island) is a very active basaltic volcano, with five eruptions between Nov 2009 and Dec 2010. Pre‐eruptive seismic crises usually last for a few hours and mainly consist of a volcano‐tectonic swarm. During the quiescent period between the volcano‐tectonic swarm and the eruptive tremor, we identify another swarm of events with a very high frequency content. These events are shallow and are located close to the future eruption site. They seem associated with the opening of the path for the magma propagating laterally at shallow depth. As these events start to occur while the magma is still in a vertical propagation phase, this seismicity seems to be related with the generic response of the volcano to the stress perturbation and not directly induced by the magma pressure. This new observation brings new insights to short‐term forecasting of the eruption location.
Sediment eddy diffusivity in meandering turbulent jets: Implications for levee formation at river mouths
Authors: Mariotti G. , Falcini F. , Geleynse N. , Guala M. , Sun T. , Fagherazzi S.
Published: August 2013

Depositional patterns characteristic of river mouths are controlled by the sediment‐laden turbulent jet exiting from rivers. Here we show that jet instability, developing at river mouths with small width‐to‐depth ratio, can affect these patterns. Numerical simulations indicate that sediment eddy diffusivity, which is a measure of the spreading of sediments out of the jet core, depends on the interplay between sediment settling and large coherent flow structures, which are associated with unstable jets. Our results suggest that optimal conditions for eddy diffusivity are met when the time scale of sediment settling is equal to the characteristic eddy time scale. In this condition, sediments are deposited at the farthest distance from the jet centerline, thus promoting the formation of lateral deposits. Settling time scales much greater or much smaller than the eddy time scale is associated with low eddy diffusivity, which promotes the formation of a central deposit. Such eddy‐mediated sediment transport is more evident in the Zone Of Established Flow than in the Zone Of Flow Establishment, since the former is characterized by fully developed vortices. A simplified model is proposed to estimate the settling and eddy time scales and to predict the optimal condition for levee formation.
Identification of inferior pancreaticoduodenal artery during pancreaticoduodenectomy using augmented reality‐based navigation system
Authors: Onda Shinji , Okamoto Tomoyoshi , Kanehira Masaru , Suzuki Fumitake , Ito Ryusuke , Fujioka Shuichi , Suzuki Naoki , Hattori Asaki , Yanaga Katsuhiko
Published: August 2013

Background

In pancreaticoduodenectomy (PD), early ligation of the inferior pancreaticoduodenal artery (IPDA) before efferent veins has been advocated to decrease blood loss by congestion of the pancreatic head to be resected. In this study, we herein report the utility of early identification of the IPDA using an augmented reality (AR)‐based navigation system (NS).

Methods

Seven nonconsecutive patients underwent PD using AR‐based NS. After paired‐point matching registration, the reconstructed image obtained by preoperative computed tomography (CT) was fused with a real‐time operative field image and displayed on 3D monitors. The vascular reconstructed images, including the superior mesenteric artery, jejunal artery, and IPDA were visualized to facilitate image‐guided surgical procedures. We compared operating time and intraoperative blood loss of six patients who successfully underwent identification of IPDA using AR‐based NS (group A) with nine patients who underwent early ligation of IPDA without using AR (group B) and 18 patients who underwent a conventional PD (group C).

Results

The IPDA or the jejunal artery was rapidly identified and ligated in six patients. The mean operating time and intraoperative blood loss in group A was 415 min and 901 ml, respectively. There was no significant difference in operating time and intraoperative blood loss among the groups.

Conclusions

The AR‐based NS provided precise anatomical information, which allowed the surgeons to rapidly identify and perform early ligation of IPDA in PD.
In vivo and in vitro evaluation of the effect of 2‐(4‐morpholinethyl)1‐phenylcyclohexanecarboxylate on inflammation‐sensitized hyperoxia‐induced developing brain injury
Authors: Posod Anna , Krepp Yvonne , Urbanek Martina , Stock Katharina , Kiechl‐Kohlendorfer Ursula , Griesmaier Elke
Published: August 2013

Supraphysiological oxygen concentrations are toxic to the developing brain. Inflammatory processes increase the risk for brain injury. Sigma‐1 receptor agonists are potent suppressors of inflammation‐related events and are powerful immunomodulatory and antioxidative agents. Neuroprotective effects of sigma‐1 receptor agonists have been described previously for neonatal and adult models of brain injury. The aim of this study was to assess the selective sigma‐1 receptor agonist 2‐(4‐morpholinethyl)1‐phenylcyclohexanecarboxylate (PRE‐084) in models of inflammation‐sensitized hyperoxia‐induced developing brain injury. For in vivo studies, rat pups were randomly presensitized with 1) lipopolysaccharide or 2) vehicle on postnatal day 3. On day 6, pups received either 1) PRE‐084 or 2) vehicle and were subsequently exposed to hyperoxic conditions for 6, 12, or 24 hr. At the end of exposure, animals were sacrificed and brains were processed for caspase‐3 analysis using immunohistochemistry and Western blotting. For in vitro studies, oligodendroglial cells were subjected to hyperoxic conditions in the presence or absence of proinflammatory cytokines and PRE‐084. Cell membrane integrity and cell viability were assessed by means of lactate dehydrogenase and 2,3‐bis‐(2‐methoxy‐4‐nitro‐5‐sulfophenyl)‐2H‐tetrazolium‐5‐carboxanilide (XTT) assays. Inflammatory presensitization significantly increased hyperoxia‐induced injury both in vivo and in vitro. PRE‐084 administration did not attenuate damage. Sigma‐1 receptor agonists have been described as a promising therapeutic strategy for brain injury. We were not able to confirm this in the present model. The exact mechanisms of action of sigma‐1 receptor agonists as well as the pathophysiologic pathways involved in hyperoxia‐induced injury in the developing brain remain to be elucidated. © 2013 Wiley Periodicals, Inc.
The resonance and pre‐resonance Raman scattering in the low energy 11B2u and 11B3u states of 1,4,5,8‐naphthalenetetracarboxy dianhydride in terms of DFT methods. The aggregation of NTCDA molecules in the ethanol and methanol solutions
Authors: Makowski M. , Zazakowny P. , Pawlikowski M. T.
Published: August 2013

The absorption, pre‐resonance, and resonance Raman spectra of 1,4,5,8‐naphthalenetetracarboxy dianhydride (NTCDA) molecule are examined in terms of time‐dependent density functional theory at TD‐B3LYP/aug‐cc‐pVDZ and TD‐SVWN/aug‐cc‐pVDZ levels. The Franck–Condon analysis performed for two 11Ag → 11B2u and 11Ag → 11B3u overlapping transitions leads to an excellent agreement between the theoretical predictions and experimental data providing that the calculated absorption is confronted with that measured in chloroform or acetonitrile but not in the ethanol (methanol) solution. We argue that absorption spectra measured in ethanol solution already known in literature do not characterize NTCDA molecule. On the basis of the absorption and resonance scattering spectra, we may deliberate that the dimerization of NTCDA is responsible for utterly different absorption observed in ethanol (methanol) comparing with less active solvents (chloroform and acetonitrile). That conclusion is supported by the dimer vibronic theory and by the TD‐B97d computations at the aug‐cc‐pVDZ basis set level. Copyright © 2013 John Wiley & Sons, Ltd.
A standardized mean difference effect size for multiple baseline designs across individuals
Authors: Hedges Larry V. , Pustejovsky James E. , Shadish William R.
Published: August 2013

Single‐case designs are a class of research methods for evaluating treatment effects by measuring outcomes repeatedly over time while systematically introducing different condition (e.g., treatment and control) to the same individual. The designs are used across fields such as behavior analysis, clinical psychology, special education, and medicine. Emerging standards for single‐case designs have focused attention on methods for summarizing and meta‐analyzing findings and on the need for effect sizes indices that are comparable to those used in between‐subjects designs. In the previous work, we discussed how to define and estimate an effect size that is directly comparable to the standardized mean difference often used in between‐subjects research based on the data from a particular type of single‐case design, the treatment reversal or (AB)k design. This paper extends the effect size measure to another type of single‐case study, the multiple baseline design. We propose estimation methods for the effect size and its variance, study the estimators using simulation, and demonstrate the approach in two applications. Copyright © 2013 John Wiley & Sons, Ltd.
Physicochemical and biochemical characterization of transgenic papaya modified for protection against Papaya ringspot virus
Authors: Roberts Madeen , Minott Donna A , Pinnock Simone , Tennant Paula F , Jackson Jose C
Published: August 2013

BACKGROUND

Papaya, a nutritious tropical fruit, is consumed both in its fresh form and as a processed product worldwide. Major quality indices which include firmness, acidity, pH, colour and size, are cultivar dependent. Transgenic papayas engineered for resistance to Papaya ringspot virus were evaluated over the ripening period to address physicochemical quality attributes and food safety concerns.

RESULTS

With the exception of one transgenic line, no significant differences (P > 0.05) were observed in firmness, acidity and pH. Lightness (L*) and redness (a*) of the pulps of non‐transgenic and transgenic papaya were similar but varied over the ripening period (P < 0.05). Fruit mass, though non‐uniform (P < 0.05) for some lines, was within the range reported for similar papaya cultivars, as were shape indices of female fruits. Transgene proteins, CP and NPTII, were not detected in fruit pulp at the table‐ready stage.

CONCLUSION

The findings suggest that transformation did not produce any major unintended alterations in the physicochemical attributes of the transgenic papayas. Transgene proteins in the edible fruit pulp were low or undetectable. © 2013 Society of Chemical Industry
Three‐dimensional interaction and autostereoscopic display system using gesture recognition
Authors: Zhang Jie , Xu Xiao‐Qing , Liu Jun , Li Lei , Wang Qiong‐Hua
Published: August 2013

We propose a 3D interaction and autostereoscopic display system that use gesture recognition, which can manipulate virtual objects in the scene directly by hand gestures and can display objects in 3D stereoscopy. The system consists of a gesture recognition and manipulation part as well as an autostereoscopic display as an interactive display part. To manipulate the 3D virtual scene, a gesture recognition algorithm is proposed, which use spatial‐temporal sequences of feature vectors to match predefined gestures. To get smooth 3D visualization, we utilize the programmable graphics pipeline in graphic processing unit to accelerate data processing. We develop a prototype system for 3D virtual exhibition. The prototype system reaches frame rates of 60 fps and operates efficiently with a mean recognition accuracy of 90%.
Molecularly imprinted SPE coupled with HPLC for the selective separation and enrichment of alkyl imidazolium ionic liquids in environmental water samples
Authors: Xia Gao , Jing Fan , Guifen Zhu , Xiaolong Wang , Jianji Wang
Published: August 2013

A novel 1‐butyl‐3‐methylimidazolium chloride ionic liquid surface imprinted solid‐phase sorbent was synthesized. The as‐prepared material was characterized by SEM, Brunauer–Emmett–Teller surface area analysis and Fourier Transform IR measurements. Then its adsorption properties for alkyl imidazolium ionic liquids, including adsorption capacities, adsorption kinetics, and properties of selective separation and enrichment were studied in detail. It was shown that the ionic liquid surface imprinted polymer exhibited high selective recognition characteristics for the imidazolium chloride ionic liquids with short alkyl chains (CnmimCl, n = 2, 4, 6, 8) and the adsorption equilibrium was achieved within 25 min. Various parameters were optimized for the 1‐butyl‐3‐methylimidazolium chloride ionic liquid surface imprinted polymer SPE column, such as flow rate, eluent solvent, selectivity, and reusability of the column. Then, the SPE column coupled with HPLC was used for the determination of alkyl imidazolium ionic liquids. Experimental results showed that the existence of their structural analogs and common concomitants in environmental matrices did not affect the enrichment of 1‐butyl‐3‐methyl imidazolium chloride ionic liquid. The average recoveries of 1‐butyl‐3‐methylimidazolium chloride ionic liquid in spiked water samples were in the range of 92.0–102.0% with the RSD lower than 5.8%.
The role of natural and UV‐induced skin pigmentation on low‐fluence IPL‐induced side effects: A randomized controlled trial
Authors: Thaysen‐Petersen Daniel , Lin Jennifer Y. , Nash JF. , Beerwerth Frank , Wulf Hans C. , Philipsen Peter A. , Haedersdal Merete
Published: August 2013

Background and Objectives

The risk of adverse skin effects following light‐based hair removal is greater in pigmented skin based on the theory of selective photothermolysis. Thus sunlight‐induced pigment i.e., facultative pigmentation, increases the risk of adverse skin effects, perhaps disproportionately. The aim of this study was to evaluate the influence of constitutive and facultative skin pigmentation on low‐fluence intense pulsed light (IPL)‐induced adverse skin effects.

Study Design/Materials and Methods

Twenty‐one subjects with Fitzpatrick skin type II–IV were enrolled. Two buttock blocks were randomized to receive 0 or 8 solar simulated ultraviolet radiation (UVR) exposures of consecutively increasing Standard Erythema Doses (2–4 SED). Each block was subdivided into four sites, randomized to receive IPL of 0, 7, 8, or 10 J/cm2, once a week for 3 weeks. Biopsies were taken 16–24 hours after the first IPL exposure and subjects were seen 1 and 4 weeks after the last IPL exposure. Outcome measures were: (i) skin reactions, (ii) pain, (iii) mRNA expression of pigment‐markers microphthalmia‐associated transcription factor (MITF) and pro‐opiomelanocortin (POMC), and (iv) clinical appearance of biopsy wounds.

Results

Skin pigmentation increased after UVR (baseline median 13.8%, after UVR 28.1%, P = 0.0001) in all skin types. Subjects reported low pain intensities (median 1.5, scale 0–10) and experienced transient erythema immediately after IPL exposure. No persistent erythema, blisters, crusting, textual, or pigment changes were observed. The risk of erythema and pain intensities increased with IPL dose and skin pigmentation (P < 0.03). There was no difference in pain or skin reactions in skin with similar degree of natural and facultative pigmentation (P ≥ 0.104). Expression of cellular pigment‐markers was not influenced by IPL exposure, neither in constitutive nor in facultative pigmented skin. Clinical appearance of biopsy wounds was unaffected by IPL exposure.

Conclusion

The prevalence and intensity of low‐fluence IPL‐induced adverse skin effects depended on IPL dose and skin pigmentation regardless of the origin, i.e., constitutive versus UV induced. Lasers Surg. Med. 46:104–111, 2014. © 2013 Wiley Periodicals, Inc.
Fabrication and Characterization of Novel High Modulus, Two‐Stage Reactive Thiol‐Acrylate Composite Polymer Systems
Authors: Nair Devatha P. , Cramer Neil B. , McBride Mathew K. , Gaipa John C. , Lee Nathan C. , Shandas Robin , Bowman Christopher N.
Published: August 2013

High modulus two‐stage reactive polymer systems are fabricated and characterized in regards to their thermomechanical properties and behavior. The polymer networks comprise thiol‐acrylate formulations in which a polymer matrix is initially formed via an amine catalyzed thiol‐Michael addition ‘click’ reaction, eventually followed by photoinitiated, free radical polymerization of the excess acrylic functional groups to result in formation of a highly crosslinked, high modulus polymer material. Composites were formed and evaluated using two distinct polymerizable thiol‐acrylate formulations, each with three different filler types. Here, the fillers were used primarily to improve the mechanical performance of the polymer material following the initial Michael addition reaction though improvements were also observed in some materials following the photopolymerization as well. The fillers used were 0.7 µm methacrylated silica particles, translucent Kevlar veil and PET mesh. Thermomechanical analysis showed that the fillers resulted in a significant increase in the modulus in both the polymer networks formed at the end of each of the orthogonal reactions without a significant change in the glass transition temperatures (Tg). The two‐stage matrix formed with a hexa‐acrylate matrix and 20 volume % silica particles showed a 125% increase in the modulus at the end of the Michael‐addition reaction and a 100% increase in the modulus after photopolymerization of the acrylates, when compared with the modulus of the unfilled polymer.
PEG‐Based Microgels to Modify Biomaterials Surfaces
Authors: Wu Yong , Wang Qichen , Libera Matthew
Published: August 2013

Microgels are hydrogel particles ∼0.1–10 microns in size which have been increasingly explored for biomaterials applications. They can be designed to sequester drugs based on both hydrophobic and electrostatic interactions, and different strategies exist to trigger drug release from them. Microgels based on poly(ethylene glycol) are particularly attractive because of their intrinsic antifouling properties, the flexibility they bring to microgel design and synthesis, and the regulatory precedents set by PEG's use in a number of FDA‐approved applications. This paper briefly reviews progress in the field of PEG‐based microgels. We give examples illustrating their electrostatic deposition onto biomaterial surfaces and their ability to sequester antimicrobials for applications involving biomaterials‐associated infection.
Field‐Structured Polymer Composites
Authors: Martin James E.
Published: August 2013

The use of multiaxial magnetic fields to create particle composites with controlled structures and properties is discussed. These field‐structured composites can have greatly enhanced isotropic or anisotropic properties, and have applications to sensing, actuation, and thermal transport. In this article the synthesis of these materials is discussed, and a variety of composite structures are shown. The magnetic permeability and thermal conductivity are given as specific examples of the utility of multiaxial field structuring.
Nanogels as a Basis for Network Construction
Authors: Dailing Eric , Liu JianCheng , Lewis Steven , Stansbury Jeffery
Published: August 2013

Reactive nanogels with diverse chemical and physical compositions were synthesized using solution free radical polymerization. Conventional monomer resins show a reduction in polymerization shrinkage and stress as well as improved bond strength when nanogels are used as a filler. Nanogels dispersed in inert solvent at appropriate concentrations form macroscopic networks with chemical compositions that are not directly available from the starting monomers.
Hydrolytically Degradable Thiol–ene Hydrogels for Protein Release
Authors: Rehmann Matthew S. , Garibian Andrew C. , Kloxin April M.
Published: August 2013

A new degradable PEG‐diester‐dinorbornene/PEG‐triester‐trithiol hydrogel was evaluated for protein release. The hydrogel polymerized rapidly with seconds of UV irradiation and subsequently hydrolytically degraded in aqueous buffer over the course of approximately 3 weeks. Further, the hydrogel enabled the encapsulation and release of a model protein, bovine serum albumin (BSA), over 7 days with ∼ 90% released at 48 h. This study serves as a proof‐of‐concept for the creation of hydrolytically degradable, PEG‐ester‐thiol‐based hydrogels by a photoinitiated step growth mechanism for protein release. With this approach, degradation and release rates could be tuned by varying the monomer molecular weight and functionality in future studies.
Preparative TREF ‐ HT‐HPLC ‐ HPer DSC: Linking Molecular Characteristics and Thermal Properties of an Impact Poly(propylene) Copolymer
Authors: Cheruthazhekatt Sadiqali , Pijpers Thijs F. J. , Mathot Vincent B. F. , Pasch Harald
Published: August 2013

The microstructure and thermal behaviour of complex polyolefins affect the product properties significantly. Therefore a thorough characterization of such semi‐crystalline materials is necessary to understand the relationship between molecular structure and melting and crystallization behaviour. In the present work, the correlation between the chain structure and thermal behaviour of various components in a complex midelution temperature TREF fraction (80 °C) of a commercial impact poly(propylene) copolymer were studied by using a combination of prep TREF and a highly selective separation method, HT HPLC, followed by thermal analysis of resulting dual fractions via a fast scanning DSC technique (HPer DSC). HT‐HPLC can separate polymer chains according to their microstructure (chemical composition, tacticity and chain branching) within in short analysis time. The ability to measure the thermal properties of minute amounts of materials by HPer DSC helps to correlate their chemical structure with the melting and crystallization behaviour. In this way, the present hyphenated technique (prep‐TREF‐HT‐HPLC‐HPer DSC) provides a powerful tool to separate and analyse complex mixtures of polymer components having different chemical structures and thermal properties.
Inhomogeneity Development During Slow, Irreversible Cross‐Linking of Gelatin
Authors: Souguir Hayfa , Baumberger Tristan
Published: August 2013

Gelatin gels, permanently cross‐linked following two different routes, exhibit the same phenomenology in which their turbidity builds‐up in concert with their elastic modulus. This is analyzed in terms of a minimal model for the chemo‐osmotic coupling mechanism first proposed by Bastide and Candau (in: “Physical Properties of Polymeric Gels”, J.‐P. Cohen Addad Ed., J. Wiley & Sons, New York 1996). The analysis points out the important role of labile counterions, which usually stiffen (osmotically) the gel, thereby hindering the coupling. This might be the reason why thisa priorigeneric mechanism was not observed earlier.
Stimuli‐Responsive Polymer Networks with β‐Cyclodextrin and Ferrocene Reversible Linkage Based on Linker Chemistry
Authors: Zhang Huijuan , Peng Liao , Xin Yan , Yan Qiang , Yuan Jinying
Published: August 2013

Different from the chemical structure and self‐assembly behavior of traditional block copolymer, a homopolymer self‐assembly approach with reversible linkage based on linker chemistry has been developed. The strategy could be used for the preparation of stimuli‐responsive polymer networks with reversible linkers. A redox‐responsive supramolecular hydrogel was obtained by two hydrophilic copolymers (poly(N, N'‐dimethylacrylamide‐r‐glycidyl methacrylateglycidyl methacrylate) and poly(N, N'‐dimethylacrylamide‐r‐hydroxyethyl methacrylateglycidyl methacrylate)) with β‐CD and ferrocene pendent groups, respectively. The hydrogel exhibited gel‐sol transition after the addition of an oxidizing agent FeCl3 and returned to its gel state when a reducing agent ascorbic acid was added. SEM observation showed that the hydrogel had a porous network structure. The host‐guest interaction between β‐CD and ferrocene was a dominant driving force for the formation of the hydrogel.
Importance of Multi‐Angle Light Scattering in Polyolefin Characterization
Authors: Podzimek Stepan
Published: August 2013

The paper reviews basic principles and applications of multi‐angle light scattering (MALS) employed as a detector for high temperature size exclusion chromatography (SEC). The presented MALS data were acquired with state‐of‐the‐art MALS instrumentation. A special attention is paid to the specific elution behavior of branched polyolefins during their SEC separation, to the characterization of long chain branching, and to overcoming the limitations arising from abnormal SEC elution. The MALS detection is also presented as highly reproducible method of the determination of molar mass averages and extremely sensitive technique for the detection of high molar mass fractions.
Evidences of Long‐Chain Branching in Ziegler‐Natta Polyethylene Homopolymers as Studied via SEC‐MALS and Rheology
Authors: Yu Youlu , Rohlfing David C.
Published: August 2013

Comprehensive polymer architectural studies were carried out on a group of Ziegler‐Natta (Z‐N) polyethylene homopolymers via size‐exclusion chromatography coupled with multi‐angle light scattering (SEC‐MALS) and rheology. Although Z‐N resins are traditionally viewed as linear polymers, both SEC‐MALS and rheology results strongly indicate that there are topological variations, presumably long‐chain branching (LCB) or possibly hyper‐branches, in this group of supposedly linear Z‐N homopolymers. These Z‐N homopolymers exhibit very complex elution behavior that resulted in anomalous elution profiles in SEC. It appeared that some high molecular weight (MW) and long‐chain branched components followed a non‐size exclusion separation mechanism on SEC columns, co‐eluting with low MW and linear polyethylene components, causing a delayed elution. The possible origin of LCB in these Z‐N polymers is also discussed.
Preparation and Characterization of PE‐g‐AIt
Authors: da Silva Marco A. , Galland Griselda B.
Published: August 2013

The grafting of HDPE and LLDPE with itaconic acid (AIt) was made by reactive extrusion using the peroxide 2,5‐dimethyl‐2,5‐di(tert‐butyli) peroxy hexane (trigonox 101) as initiator. The graft efficiency was evaluated using FTIR to identify bands of carbonyl groups in the polymer. It is influence on the addition of itaconic acid in the structure of the polymer chain was evaluated using CRYSTAF and microcalorimetry, where it was show that the incorporated acid causes a narrow crystallization profile and the decrease of the percentage of the soluble fraction at 30 °C. The polymers were fractionated by molecular weight and chemical composition to check the distribution of the AIt incorporation, the percentage of AIt was quantified in each fraction by FTIR, and it was show that the incorporation of AIt occurred homogeneously in all the chains.
Ion Polymer Interactions in DNA Solutions and Gels
Authors: Horkay Ferenc
Published: August 2013

Systematic investigations using small angle neutron scattering (SANS) were made to reveal the effect of calcium ions on the structure of DNA gels and solutions in near‐physiological salt solutions. To describe the neutron scattering response two characteristic distances are required. The shorter length scale, R (≈10 Å), was found to be governed by the geometry of the DNA chain and is close to the cross‐sectional radius of the double helix. The longer length scale L corresponds to the mesh size of the network of overlapping polymer chains. L decreases with increasing DNA concentration as L ∝ cDNA−0.73. With increasing CaCl2 concentration both L and the scattering intensity increase. The increase in the scattering intensity reflects the reduction of the osmotic modulus as the calcium ion concentration increases. The values of the osmotic modulus derived from osmotic swelling pressure measurements are in reasonable agreement with those obtained from SANS.
Chemical Composition Distribution and Temperature Rising Elution Fractionation of Linear Olefin Block Copolymers
Authors: Anantawaraskul Siripon , Sottesakul Suwicha , Siriwongsarn Ekaphol , Soares João B.P.
Published: August 2013

Linear olefin block copolymers (OBCs) have statistical multi‐block structures and exhibit unique properties that are different from those of other polyolefin elastomers. In this work, the microstructure details of OBCs were investigated using a Monte Carlo model. Theoretical TREF profiles for these materials were simulated using a modified version of the TREF model previously developed in our group. Effects of polymerization parameters on OBC microstructures and TREF profiles were investigated. Distinctions among chemical composition distribution, longest ethylene sequence distribution, and TREF profiles were observed and discussed.
Optimum Cr(acac)3 Concentration for NMR Quantitative Analysis of Polyolefins
Authors: Zhou Zhe , He Yiyong , Qiu Xiaohua , Redwine David , Potter Janece , Cong Rongjuan , Miller Matthew
Published: August 2013

Olefin copolymers are major industry products. 13C NMR is a critical analytical tool to characterize the composition as well as the monomer sequence distribution. Due to the low natural abundance, small magnetogyric ratio and long spin lattice relaxation time (T1) of 13C, a large number of scans are needed to obtain reasonable signal‐to‐noise (S/N) for quantitative analyses. This needs a significant amount of NMR time. A relaxation reagent, such as Cr(acac)3, can reduce the T1 and abolish unwanted NOE. Based on the effect of Cr(acac)3 on 13C T1 and line width of HDPE and an ethylene‐octene copolymer, 0.025M Cr(acac)3 is recommended for routine 13C NMR experiments and 0.05 M Cr(acac)3 can be used with less stringent resolution requirements. The end‐group and unsaturation analysis of polyolefins by 1H NMR is complicated by three factors: 1) Low signal level; 2) Significant and anomalous molecular weight and concentration dependences for the 1H T1; 3) Sample degradation induced by long acquisition time. To solve these problems, Cr(acac)3 can be added to reduce the 1H T1, hence NMR instrument time. By the systematic study of the effect of Cr(acac)3 on the 1H T1 and spectrum quality, the optimum Cr(acac)3 concentration was found to be 0.001 M, at which concentration, the longest 1H T1 of polyolefins is reduced by about a factor of 4, while retaining almost the same spectral quality. Sample degradation is also avoided due to much shorter acquisition time. This provides a robust and efficient procedure for characterizing parts‐per‐million level unsaturated structures and end‐groups in polyolefins.
Simultaneous Deconvolution of MWD and CCD of Ethylene/1‐Olefin Copolymers Using Genetic Algorithm
Authors: Nanthapoolsub Uthane , Anantawaraskul Siripon , Saengkhamkhom Khomwat
Published: August 2013

Multiple‐site‐type catalytic systems produce ethylene/1‐olefin copolymers with broad molecular weight distribution (MWD) and chemical composition distribution (CCD) because each active site type produces chains with distinct chain microstructures. Simultaneous deconvolution of the MWD and CCD can be used to identify the number of active site types and chain microstructures produced on each active site type by performing parameter estimation to minimize the sum of the squares of differences between experimental and model data. However, conventional optimization algorithms often rely on the adequate initial guess. In this work, a genetic algorithm, which is a stochastic optimization search heuristic that mimics the natural evolution process, was implemented during the simultaneous deconvolution. The proposed approach was validated with simulated data of model ethylene/1‐butene copolymers produced using a system with three active site types.
Advances in Thermal Gradient Interaction Chromatography and Crystallization Techniques for Composition Analysis in Polyolefins
Authors: Monrabal Benjamin , López Esther , Romero Loli
Published: August 2013

Since the introduction of high temperature interaction chromatography for the analysis of polyolefins the technique has demanded a particular interest in the analysis of elastomers where crystallization techniques will meet a limitation given the low crystallinity of these polymers. In this paper the introduction of non carbon adsorption supports such as molybdenum sulfide, boron nitride and tungsten sulfide with equivalent separation to graphitized carbon packing in TGIC analysis of polyolefins is presented. A mechanism for the separation of polyolefins by adsorption chromatography on layered substrates is proposed. The influence of solvent polarity in interaction chromatography is discussed.
Thermally induced process‐related contaminants: The example of acrolein and the comparison with acrylamide
Authors: Guth Sabine , Habermeyer Michael , Baum Matthias , Steinberg Pablo , Lampen Alfonso , Eisenbrand Gerhard
Published: August 2013

α,β‐Unsaturated aliphatic carbonyl compounds are naturally widespread in food, but are also formed during the thermal treatment of food. This applies, for example, to the genotoxic carcinogen acrylamide (AA), but also to acrolein (AC), the simplest α,β‐unsaturated aldehyde. First observations indicate that human exposure to AC may be higher than the exposure to AA. The DFG Senate Commission on Food Safety therefore compared data on AC and AA available in the scientific literature, evaluating current knowledge on formation, occurrence, exposure, metabolism, biological effects, toxicity, and carcinogenicity and defined knowledge gaps as well as research needs in an opinion on November 19, 2012, in German. The English version was agreed on April 17, 2013.
Correlation of substituted aromatic β‐diketones' characteristic protons chemical shifts with Hammett substituent constants
Authors: Zawadiak Jan , Mrzyczek Marek
Published: August 2013

Influence of dibenzoylmethane's substituents in meta and para positions on chemical shift values of tautomers' characteristic protons was investigated in four solvents with 1H NMR spectroscopy: acetone‐d6, benzene‐d6, CDCl3 and deuterated dimethyl sulfoxide (DMSO‐d6). It was proved that the influence of substituents on chemical shifts strongly depends on the kind of the solvent; the greatest changes were observed in benzene‐d6 and the smallest in CDCl3. In acetone‐d6 and DMSO‐d6, the influence of substituents on chemical shifts is similar and the most regular. It allowed a fair correlation of chemical shifts of para‐substituted dibenzoylmethane derivatives' characteristic protons with Hammett substituent constants in these solvents. In CDCl3, characteristic protons' chemical shifts were near 1H NMR spectroscopy measurement error limits, and, therefore, correlation with Hammett substituent constants in this solvent was unsatisfactory. In benzene, although the changes of chemical shifts are the most evident, the changes are also the most irregular, and, therefore, correlation in this solvent failed completely. Results of meta‐substituted derivatives were much more irregular, and their correlation with Hammett substituent constants was poor in all investigated solvents. Copyright © 2013 John Wiley & Sons, Ltd.