bluuebunny/crossref_metadata_2025 huggingface dataset:
Suicide Note Sentiment Classification: A Supervised Approach Augmented by Web Data
Authors: Xu Yan , Wang Yue , Liu Jiahua , Tu Zhuowen , Sun Jian-Tao , Tsujii Junichi , Chang Eric
Published: January 2012

Objective

To create a sentiment classification system for the Fifth i2b2/VA Challenge Track 2, which can identify thirteen subjective categories and two objective categories.

Design

We developed a hybrid system using Support Vector Machine (SVM) classifiers with augmented training data from the Internet. Our system consists of three types of classification-based systems: the first system uses spanning n-gram features for subjective categories, the second one uses bag-of-n-gram features for objective categories, and the third one uses pattern matching for infrequent or subtle emotion categories. The spanning n-gram features are selected by a feature selection algorithm that leverages emotional corpus from weblogs. Special normalization of objective sentences is generalized with shallow parsing and external web knowledge. We utilize three sources of web data: the weblog of LiveJournal which helps to improve the feature selection, the eBay List which assists in special normalization of information and instructions categories, and the suicide project web which provides unlabeled data with similar properties as suicide notes.

Measurements

The performance is evaluated by the overall micro-averaged precision, recall and F-measure.

Result

Our system achieved an overall micro-averaged F-measure of 0.59. Happiness_peacefulness had the highest F-measure of 0.81. We were ranked as the second best out of 26 competing teams.

Conclusion

Our results indicated that classifying fine-grained sentiments at sentence level is a non-trivial task. It is effective to divide categories into different groups according to their semantic properties. In addition, our system performance benefits from external knowledge extracted from publically available web data of other purposes; performance can be further enhanced when more training data is available.
Statistical and Similarity Methods for Classifying Emotion in Suicide Notes
Authors: Roberts Kirk , Harabagiu Sanda M.
Published: January 2012

In this paper we report on the approaches that we developed for the 2011 i2b2 Shared Task on Sentiment Analysis of Suicide Notes. We have cast the problem of detecting emotions in suicide notes as a supervised multi-label classification problem. Our classifiers use a variety of features based on (a) lexical indicators, (b) topic scores, and (c) similarity measures. Our best submission has a precision of 0.551, a recall of 0.485, and a F-measure of 0.516.
Three Hybrid Classifiers for the Detection of Emotions in Suicide Notes
Authors: Liakata Maria , Kim Jee-Hyub , Saha Shyamasree , Hastings Janna , Rebholz-Schuhmann Dietrich
Published: January 2012

We describe our approach for creating a system able to detect emotions in suicide notes. Motivated by the sparse and imbalanced data as well as the complex annotation scheme, we have considered three hybrid approaches for distinguishing between the different categories. Each of the three approaches combines machine learning with manually derived rules, where the latter target very sparse emotion categories. The first approach considers the task as single label multi-class classification, where an SVM and a CRF classifier are trained to recognise fifteen different categories and their results are combined. Our second approach trains individual binary classifiers (SVM and CRF) for each of the fifteen sentence categories and returns the union of the classifiers as the final result. Finally, our third approach is a combination of binary and multi-class classifiers (SVM and CRF) trained on different subsets of the training data. We considered a number of different feature configurations. All three systems were tested on 300 unseen messages. Our second system had the best performance of the three, yielding an F1 score of 45.6% and a Precision of 60.1% whereas our best Recall (43.6%) was obtained using the third system.
Oceanographic forcing of nutrient uptake and release over a fringing coral reef
Authors: Wyatt Alex S. J. , Falter James L. , Lowe Ryan J. , Humphries Stuart , Waite Anya M.
Published: January 2012

Nitrate and nitrite (NOx) and phosphate (PO4) dynamics over Ningaloo Reef, Western Australia, are shown to depend on oceanographic forcing of coupled mass transfer limited (MTL) gross uptake and gross release from remineralized oceanic particulate organic matter (POM). Estimates of gross release rates increased significantly with increasing POM uptake and were of the same order as gross uptake rates. Gross uptake rates increased significantly with increasing oceanic concentrations and wave energy dissipation, were 35–80% higher over the reef crest (7–9 mmol NOx m−2 d−1 and 4–5 mmol PO4 m−2 d−1), and were significantly correlated with independent estimates of POM‐mediated gross NOx uptake, supporting both MTL uptake and the strong role of oceanic POM supply. The relative supply of NOx and POM was linked to the seasonal dynamics of a regional current system. In late spring, upwelling associated with seasonally strong equator‐ward winds led to increased NOx concentrations (0.71 ± 0.2 µmol L−1), POM < NOx and the reef was a net nutrient sink (5390 mmol NOx m−1 d−1 and 270 mmol PO4 m−1 d−1). In contrast, during the autumn, NOx was low (0.16 ± 0.06 µmol L−1), but POM > NOx and the reef was a net nutrient source (−7060 mmol NOx m−1 d−1 and −730 mmol PO4 m−1 d−1). The autumn enhancement of oceanic POM supply to the reef can be attributed to a regional phytoplankton bloom associated with acceleration of the oligotrophic Leeuwin Current, which may result in a significant supply of dissolved nutrients to downstream communities.
Improving semiautomated zooplankton classification using an internal control and different imaging devices
Authors: Bachiller Eneko , Fernandes Jose Antonio , Irigoien Xabier
Published: January 2012

The rapid development of image‐based methods for counting and classifying zooplankton has made it possible to analyze large numbers of samples in a semiautomated way. However, using semiautomated methods to deal with hundreds of samples increases the risk of propagating errors during the procedure. Furthermore, classification methods based on training sets require constant validation to ensure that systematic errors do not affect the results. In this study, we propose using an internal control to check the quality of the procedure for counting and classifying zooplankton. We also evaluate the advantages and disadvantages of two different laboratory imaging devices (scanner and photographic camera) at two resolutions (4800 dpi and 8500 dpi).
Free‐water lake metabolism: addressing noisy time series with a Kalman filter
Authors: Batt Ryan D. , Carpenter Stephen R.
Published: January 2012

Whole‐ecosystem metabolism is often estimated in lakes using high frequency free‐water measurements of dissolved oxygen (DO) taken in the upper mixed layer. DO dynamics in the metalimnion are not adequately captured by measurements made in the upper mixed layer, which could reduce the accuracy of whole‐lake metabolism estimates made from such data. However, estimating metabolism from metalimnetic DO time series can be challenging because of high variability (noise). This study used simulated and field data to determine if metabolism estimates from metalimnetic data containing noise can be improved by accounting for both process and observation error in models. When DO time series exhibited high variability, free‐water metabolism estimates obtained using a Kalman filter (which accounts for both process and observation error) were substantially more accurate than estimates obtained from models that did not account for error or accounted for process error only.
Assessing marine plankton community structure from long‐term monitoring data with multivariate autoregressive (MAR) models: a comparison of fixed station versus spatially distributed sampling data
Authors: Scheef Lindsay P. , Pendleton Daniel E. , Hampton Stephanie E. , Katz Stephen L. , Holmes Elizabeth E. , Scheuerell Mark D. , Johns David G.
Published: January 2012

We examined how marine plankton interaction networks, as inferred by multivariate autoregressive (MAR) analysis of time‐series, differ based on data collected at a fixed sampling location (L4 station in the Western English Channel) and four similar time‐series prepared by averaging Continuous Plankton Recorder (CPR) datapoints in the region surrounding the fixed station. None of the plankton community structures suggested by the MAR models generated from the CPR datasets were well correlated with the MAR model for L4, but of the four CPR models, the one most closely resembling the L4 model was that for the CPR region nearest to L4. We infer that observation error and spatial variation in plankton community dynamics influenced the model performance for the CPR datasets. A modified MAR framework in which observation error and spatial variation are explicitly incorporated could allow the analysis to better handle the diverse time‐series data collected in marine environments.
Link between local scale BC emissions in the Indo-Gangetic Plains and large scale atmospheric solar absorption
Authors: Praveen P. S. , Ahmed T. , Kar A. , Rehman I. H. , Ramanathan V.
Published: January 2012

Abstract. Project Surya has documented indoor and outdoor concentrations of black carbon (BC) from traditional biomass burning cook stoves in a rural village located in the Indo-Gangetic Plains (IGP) region of N. India from November 2009–September 2010. In this paper, we systematically document the link between local scale aerosol properties and column averaged regional aerosol optical properties and atmospheric radiative forcing. We document observations from the first phase of Project Surya and estimate the source dependent (biomass and fossil fuels) aerosol optical properties from local to regional scale. Data were collected using surface based observations of BC, organic carbon (OC), aerosol light absorption, scattering coefficient at the Surya village (SVI_1) located in IGP region and integrated with satellite and AERONET observations at the regional scale (IGP). The daily mean BC concentrations at SVI_1 showed a large increase of BC during the dry season (December to February) with values reaching 35 μg m−3. Space based LIDAR data revealed how the biomass smoke was trapped within the first kilometer during the dry season and extended to above 5 km during the pre-monsoon season. As a result, during the dry season, the variance in the daily mean single scattering albedo (SSA), the ratio of scattering to extinction coefficient, and column aerosol optical properties at the local IGP site correlated (with slopes in the range of 0.85 to 1.06 and R2>0.4) well with the "IGP_AERONET" (mean of six AERONET sites). The statistically significant correlation suggested that in-situ observations can be used to derive spatial mean forcing, at least for the dry season. The atmospheric forcing due to BC and OC exceeded 20 Wm−2 during all months from November to May, supporting the deduction that elimination of cook stove smoke emissions through clean cooking technologies will likely have a major positive impact not only on human health but also on regional climate.
Bridging the Faraoni and Selli oceanic anoxic events: late Hauterivian to early Aptian dysaerobic to anaerobic phases in the Tethys
Authors: Föllmi K. B. , Bôle M. , Jammet N. , Froidevaux P. , Godet A. , Bodin S. , Adatte T. , Matera V. , Fleitmann D. , Spangenberg J. E.
Published: January 2012

Abstract. A detailed geochemical analysis was performed on the upper part of the Maiolica Formation in the Breggia (southern Switzerland) and Capriolo sections (northern Italy). The analysed sediments consist of well-bedded, partly siliceous, pelagic carbonate, which lodges numerous thin, dark and organic-rich layers. Stable-isotope, phosphorus, organic-carbon and a suite of redox-sensitive trace-element contents (RSTE: Mo, U, Co, V and As) were measured. The RSTE pattern and Corg:Ptot ratios indicate that most organic-rich layers were deposited under dysaerobic rather than anaerobic conditions and that latter conditions were likely restricted to short intervals in the latest Hauterivian, the early Barremian and the pre-Selli early Aptian. Correlations are both possible with organic-rich intervals in central Italy (the Gorgo a Cerbara section) and the Boreal Lower Saxony Basin, as well as with the facies and drowning pattern in the Helvetic segment of the northern Tethyan carbonate platform. Our data and correlations suggest that the latest Hauterivian witnessed the progressive installation of dysaerobic conditions in the Tethys, which went along with the onset in sediment condensation, phosphogenesis and platform drowning on the northern Tethyan margin, and which culminated in the Faraoni anoxic episode. This episode is followed by further episodes of dysaerobic conditions in the Tethys and the Lower Saxony Basin, which became more frequent and progressively stronger in the late early Barremian. Platform drowning persisted and did not halt before the latest early Barremian. The late Barremian witnessed diminishing frequencies and intensities in dysaerobic conditions, which went along with the progressive installation of the Urgonian carbonate platform. Near the Barremian-Aptian boundary, the increasing density in dysaerobic episodes in the Tethyan and Lower Saxony Basins is paralleled by a change towards heterozoan carbonate production on the northern Tethyan shelf. The following return to more oxygenated conditions is correlated with the second phase of Urgonian platform growth and the period immediately preceding and corresponding to the Selli anoxic episode is characterised by renewed platform drowning and the change to heterozoan carbonate production. Changes towards more humid climate conditions were the likely cause for the repetitive installation of dys- to anaerobic conditions in the Tethyan and Boreal basins and the accompanying changes in the evolution of the carbonate platform towards heterozoan carbonate-producing ecosystems and platform drowning.
Climate forcing reconstructions for use in PMIP simulations of the Last Millennium (v1.1)
Authors: Schmidt G. A. , Jungclaus J. H. , Ammann C. M. , Bard E. , Braconnot P. , Crowley T. J. , Delaygue G. , Joos F. , Krivova N. A. , Muscheler R. , Otto-Bliesner B. L. , Pongratz J. , Shindell D. T. , Solanki S. K. , Steinhilber F. , Vieira L. E. A.
Published: January 2012

Abstract. We update the forcings for the PMIP3 experiments for the Last Millennium to include new assessments of historical land use changes and discuss new suggestions for calibrating solar activity proxies to total solar irradiance.
Estimation of future groundwater recharge using climatic analogues and Hydrus-1D
Authors: Leterme B. , Mallants D. , Jacques D.
Published: January 2012

Abstract. The impact of climate change on groundwater recharge is simulated using climatic analogue stations, i.e. stations presently under climatic conditions corresponding to a given climate state. The study was conducted in the context of a safety assessment of a future near-surface disposal facility for low and intermediate level short-lived radioactive waste in Belgium; this includes estimating groundwater recharge for the next millennia. Groundwater recharge was simulated using the Richard's based soil water balance model Hydrus-1D and meteorological time series from analogue stations. Water balance calculations showed that transition from a temperate oceanic to a warmer subtropical climate without rainfall seasonality is expected to yield a decrease in groundwater recharge (−12% for the chosen representative analogue station of Gijon, Northern Spain). Based on a time series of 24 yr of daily climate data, the long-term average annual recharge decreased from 314 to 276 mm, although total rainfall was higher (947 mm) in the warmer climate compared to the current temperate climate (899 mm). This is due to a higher soil evaporation (233 mm versus 206 mm) and higher plant transpiration (350 versus 285 mm) under the warmer climate.
Comparative Analysis of Free Optical Vibration of Lamination Composite Optical Beams Using the Boubaker Polynomials Expansion Scheme and the Differential Quadrature Method
Authors: Yücel Ugur , Gargouri-Ellouze Emna , Boubaker Karem , Atlihan Gökmen , Çallioglu Hasan , Conkur E. Sahin , Gökdogan Ahmet , Merdan Mehmet , Topcu Muzaffer , Akbar N. Sher , Nadeem S. , Yildirim Ahmet
Published: January 2012

The effects of stacking sequences of composite laminated optical beams on free vibration frequencies are investigated using two methods: the Boubaker Polynomials Expansion Scheme (pbes) and the Differential Quadrature Method (dqm). In the last decades, these two techniques have been separately performed for obtaining accurate numerical solutions to several initial boundary value problems (Vo et al. 2010, Li et al. 2008, Chen 2003, Hu et al. 2008, Karami et al. 2003, Malekzadeh et al. 2004, Khare et al. 2004, Della and Shu 2005, Ramtekkar et al. 2002, Adam 2003). Conjointly yielded results are compared and discussed.
Modeling to Study the Effect of Environmental Parameters on Corrosion of Mild Steel in Seawater Using Neural Network
Authors: Paul Subir
Published: January 2012

Prediction of corrosion rate of steel structure in seawater is a challenging task for design and corrosion engineers for existing as well as new structures, due to wide variation of its composition across the global marine environment. The major parameters influencing the rate are salinity, sulphate, dissolved oxygen, pH, and temperature. While the individual effects of these parameters on corrosion are known, the conjoint effect of the parameters together is complex and unpredictable. Endeavors have been made to model the corrosion rate from laboratory experimental data, using Artificial Neural Network to predict corrosion rate at any combinations of the above five parameters and to better understand the effects of these parameters jointly on corrosion behavior. 3D mappings clearly reveal the complex interrelationship between the variables and importance of conjoint effect of the variables rather than single variable on the corrosion rate of steel in seawater.
Functional Characterization of a Small-Molecule Inhibitor of the DKK1-LRP6 Interaction
Authors: Iozzi Sara , Remelli Rosaria , Lelli Barbara , Diamanti Daniela , Pileri Silvia , Bracci Luisa , Roncarati Renza , Caricasole Andrea , Bernocco Simonetta
Published: January 2012

Background. DKK1 antagonizes canonical Wnt signalling through high-affinity binding to LRP5/6, an essential component of the Wnt receptor complex responsible for mediating downstream canonical Wnt signalling. DKK1 overexpression is known for its pathological implications in osteoporosis, cancer, and neurodegeneration, suggesting the interaction with LRP5/6 as a potential therapeutic target. Results. We show that the small-molecule NCI8642 can efficiently displace DKK1 from LRP6 and block DKK1 inhibitory activity on canonical Wnt signalling, as shown in binding and cellular assays, respectively. We further characterize NCI8642 binding activity on LRP6 by Surface Plasmon Resonance (SPR) technology. Conclusions. This study demonstrates that the DKK1-LRP6 interaction can be the target of small molecules and unlocks the possibility of new therapeutic tools for diseases associated with DKK1 dysregulation.
Staffing Benchmarks for Clinical Laboratories: A College of American Pathologists Q-Probes Study of Laboratory Staffing at 98 Institutions
Authors: Jones Bruce A. , Darcy Teresa , Souers Rhona J. , Meier Frederick A.
Published: January 2012

Context.—Publicly available information concerning laboratory staffing benchmarks is scarce. One of the few publications on this topic summarized the findings of a Q-Probes study performed in 2004. This publication reports a similar survey with data collected in 2010.

Objective.—To assess the relationship between staffing levels in specified laboratory sections and test volumes in these sections and quantify management span of control.

Design.—The study defined 4 laboratory sections: anatomic pathology (including cytology), chemistry/hematology/immunology, microbiology, and transfusion medicine. It divided staff into 3 categories: management, nonmanagement (operational or bench staff), and doctoral (MD, PhD) supervisory staff. People in these categories were tabulated as full-time equivalents and exclusions specified. Tests were counted in uniform formats, specified for each laboratory section, according to Medicare rules for the bundling and unbundling of tests.

Results.—Ninety-eight participating institutions provided data that showed significant associations between test volumes and staffing for all 4 sections. There was wide variation in productivity based on volume. There was no relationship between testing volume per laboratory section and management span of control. Higher productivity in chemistry/hematology/immunology was associated with a higher fraction of tests coming from nonacute care patients. In both the 2004 and 2010 studies, productivity was inseparably linked to test volume.

Conclusions.—Higher test volume was associated with higher productivity ratios in chemistry/hematology/immunology and transfusion medicine sections. The impact of various testing services on productivity is section-specific.
The Three Stooges Meet the Conic Sections
Authors: Gardner Robert , Davidson Robert
Published: January 2012

Students analyze a photograph to solve mathematical questions related to the images captured in the photograph. This month, a still from a Three Stooges movie is analyzed. The mathematics involves conic sections, implicit differentiation, similar triangle geometry, and scaling factors
Geometry in Medias Res
Authors: Cukier Mimi , Asdourian Tony , Thakker Anand
Published: January 2012

Plunking students down in the middle of a geometry course—in medias res—helps them appreciate the axiomatic structure of geometry.
Teaching through Problem Solving
Authors: Fi Cos D. , Degner Katherine M.
Published: January 2012

TtPS is an approach to teaching mathematics that provides students with a way to learn mathematics with understanding.
Connecting Research to Teaching: My Answers Don't Match! Using the Graphing Calculator to Check
Authors: McCulloch Allison W. , Kenney Rachael H. , Keene Karen A.
Published: January 2012

This article reports findings from a study on what students trust and why when checking their written work with a graphing calculator results in conflicting solutions. Based on these findings, suggestions for promoting good checking practices are provided.
Technology Tips: Exploring Three-Dimensional Worlds Using Google SketchUp
Authors: Livingstone Jenny , Fleron Julian F.
Published: January 2012

Google SketchUp is free, powerful and widely used Computer Aided Design (CAD) software that can have a transformative impact on the teaching of geometry. This article introduces Google SketchUp to readers through lessons that can be integrated into geometry classrooms and also provides additional resources for readers interested in learning more.
Beryllium
Authors: Welch Laura S.
Published: January 2012

Beryllium (Be) is one of the lightest of all metals and has one of the highest melting points of any light metal. Be metal is often used in aerospace and defense applications. Beryllium‐copper alloys are used in a wide variety of applications because of their electrical and thermal conductivity, high strength and hardness. Beryllium oxide acts as a good electrical insulator in some applications. Beryllium is associated with many different health effects in humans. At high levels it causes an acute form of lung disease. Among exposed individuals, a substantial fraction develop beryllium sensitization that can lead to a chronic lung disease known as berylliosis or chronic beryllium disease (CBD). Beryllium can cause skin disease and it has been classified as a human carcinogen. The chapter presents selected pulmonary and immunologic toxicity, inhalation‐carcinogenicity, exposure assessment and regulations of beryllium and beryllium compounds.
Magnesium, Calcium, Strontium, Barium, and Radium
Authors: Genter Mary Beth
Published: January 2012

Magnesium, calcium, strontium, barium, and radium are among the alkaline‐earth metals, found in group IIA of the periodic table. Sir Humphrey Davy first described the electrochemical isolation of barium, magnesium, calcium, and strontium in 1808, and the isolation of a radium salt from waste uranium ore was described by the Curies in 1898. These metals are being presented separately from other metals in this edition. Beryllium, the lightest of the alkaline‐earth metals, is also being handled separately from the alkaline earths covered in this chapter, as beryllium has a number of special immunological and pulmonary toxicology concerns that impact workplace practices and industrial hygiene concerns. Topics covered include chemical and physical properties, production and use, exposure assessments, toxic effects, standards regulations, and guidelines for each matter.
Zinc and Cadmium Compounds
Authors: Jakubowski Marek
Published: January 2012

Zinc is widely distributed in nature. The methods for the determination of zinc in different environmental media (air, soil, water, waste, plants) have been reviewed. Zinc screenings are widely applied in the clinical practice. Zinc is essential for humans and animals. It is necessary for the function of numerous enzymes. The toxic effects of zinc have been associated with excess exposure. Zinc acetate has been found to be the most toxic of the compounds tested so far. It has been noticed that excessive zinc addition to food or water has resulted in a variety of systemic effects in the hematological and gastrointestinal systems. Genotoxicity studies conducted in a variety of test systems have failed to provide evidence for the mutagenicity. Zinc is relatively nontoxic, particularly if taken orally, except for the corrosive properties of some salts. The present chapter discusses chemical and physical properties, exposure assessment, guidelines of exposure and clinical cases for various zinc and zinc compounds.
Gallium, Indium, and Thallium
Authors: Repetto Guillermo , del Peso Ana
Published: January 2012

The chemical elements gallium, indium, and thallium belong to group IIIA in the periodic table. Unlike other metals, such as lead and arsenic, which have been featured prominently in toxicological folklore since antiquity, these are relative newcomers, discovered from 1861 to 1876. Since then, thallium has developed a well‐deserved reputation for its toxic properties and is recognized as a potent accidental, occupational, and environmental poison, with incidence in cases of homicide and suicide. Although gallium and indium are not as toxic as thallium, their production and industrial use represent an important source of exposure, particularly in the increasing manufacture of semiconductor electronic devices. Gallium compounds particularly produce pulmonary toxicity. Indium compounds induce pulmonary toxicity and also nephrotoxicity, hepatotoxicity, and developmental toxicity, whereas thallium compounds act as general poisons. Some compounds are also capable of altering various cellular defense mechanisms involved in carcinogenesis. However, many aspects of the toxicity of individual compounds in human beings, including toxicokinetics, mechanisms of action, teratogenic potential, and the best treatment, remain to be elucidated.
Titanium, Zirconium, and Hafnium
Authors: Malczewska‐Toth Barbara
Published: January 2012

Titanium, zirconium, and hafnium belong to the group IVB of the periodic table. A characteristic feature of these transition elements is the ease with which they form stable complex ions. Features that contribute to this ability are favorably high charge‐to‐radius ratios and the availability of unfilled d orbitals. The ability of forming metallic bonds is demonstrated by the existence of a wide variety of alloys among different transition metals. Other features of these metals are high densities, high melting points, and low vapor pressures. Within this group, these properties tend to increase with increasing atomic weight.

This chapter discusses the chemical and physical properties followed by the toxicity of each chemical and compound in three sections: the first section provides details on titanium, the second section on zirconium, and the third section on hafnium. Tables present the atomic number, atomic weight, and natural isotopes of titanium, zirconium, and hafnium.
Using Mean Field Theory to Guide Biofunctional Materials Design
Authors: Freudenberg Uwe , Sommer Jens‐Uwe , Levental Kandice R. , Welzel Petra B. , Zieris Andrea , Chwalek Karolina , Schneider Katja , Prokoph Silvana , Prewitz Marina , Dockhorn Ron , Werner Carsten
Published: January 2012

Cell‐instructive characteristics of extracellular matrices (ECM) resulting from a subtle balance of biomolecular and biophysical signals must be recapitulated in engineered biomaterials to facilitate regenerative therapies. However, no material explored so far allows the independent tuning of the involved molecular and physical cues due to the inherent correlation between biopolymer concentration and material properties. Addressing the resulting challenge, a rational design strategy for ECM‐inspired biohybrid hydrogels based on multi‐armed poly(ethylene glycol) and heparin, adapting a mean field approach to identify conditions at which the balance of elastic, electrostatic, and excluded volume forces results in constant heparin concentrations within swollen polymer networks with gradually varied physical properties is introduced. Applying heparin‐based biofunctionalization schemes, multiple distinct combinations of matrix parameters could be identified to effectively stimulate the pro‐angiogenic state of human endothelial cells and the differentiation of human mesenchymal stem cells. The study demonstrates the power of joint theoretical and experimental efforts in creating bioactive materials with specifically and independently controllable characteristics.
The Effect of Ageing on Exciton Dynamics, Charge Separation, and Recombination in P3HT/PCBM Photovoltaic Blends
Authors: Deschler Felix , De Sio Antonietta , von Hauff Elizabeth , Kutka Peter , Sauermann Tobias , Egelhaaf Hans‐J. , Hauch Jens , Da Como Enrico
Published: January 2012

A study of how light‐induced degradation influences the fundamental photophysical processes in the active layer of poly(3‐hexylthiophene)/[6,6]‐phenyl C61‐butyric acid methyl ester (P3HT/PCBM) solar cells is presented. Non‐encapsulated samples are systematically aged by exposure to AM 1.5 illumination in the presence of dry air for different periods of time. The extent of degradation is quantified by the relative loss in the absorption maximum of the P3HT, which is varied in the range 0% to 20%. For degraded samples an increasing loss in the number of excitons within the P3HT domains is observed with longer ageing periods. This loss occurs rapidly, within the first 15 ps after photoexcitation. A more pronounced decrease in the population of polarons than excitons is observed, which also occurs on a timescale of a few picoseconds. These observations, complemented by a quantitative analysis of the polaron and exciton population dynamics, unravel two primary loss mechanisms for the performances of aged P3HT/PCBM solar cells. One is an initial ultrafast decrease in the polaron generation, apparently not related to the exciton diffusion to the polymer/fullerene interface; the second, less significant, is a loss in the exciton population within the photoexcited P3HT domains. The steady‐state photoinduced absorption spectra of degraded samples exhibits the appearance of a signal ascribed to triplet excitons, which is absent for non‐degraded samples. This latter observation is interpreted considering the formation of degraded sites where intersystem crossing and triplet exciton formation is more effective. The photovoltaic characteristics of same blends are also studied and discussed by comparing the decrease in the overall power conversion efficiency of solar cells.
Electrochemical Micromachining as an Enabling Technology for Advanced Silicon Microstructuring
Authors: Bassu Margherita , Surdo Salvatore , Strambini Lucanos Marsilio , Barillaro Giuseppe
Published: January 2012

Based on previous theoretical and experimental results on the electrochemical etching of silicon in HF‐based aqueous electrolytes, it is shown for the first time that silicon microstructures of various shapes and silicon microsystems of high complexity can be effectively fabricated in any research lab with sub‐micrometer accuracy and high aspect ratio values (about 100). This is well beyond any up‐to‐date wet or dry microstructuring approach and is achieved using a wet etching, low‐cost technology: silicon electrochemical micromachining (ECM). Dynamic control of the etching anisotropy (from 1 to 0) as the electrochemical etching progresses allows the silicon dissolution to be switched in real‐time from the anisotropic to the isotropic regime and enables advanced silicon microstructuring to be achieved through the use of high‐aspect‐ratio functional and sacrificial structures, the former being functional to the microsystem operation and the latter being sacrificed for accurate microsystem fabrication. World‐wide dissemination of the ECM technology for silicon microstructuring is envisaged in the near future, due to its low cost and high flexibility, with high‐potential impact on, though not limited to, the broad field of microelectronics and microfabrication.
Protein/Polymer‐Based Dual‐Responsive Gold Nanoparticles with pH‐Dependent Thermal Sensitivity
Authors: Strozyk Malte S. , Chanana Munish , Pastoriza‐Santos Isabel , Pérez‐Juste Jorge , Liz‐Marzán Luis M.
Published: January 2012

This article presents the synthesis and physicochemical behavior of dual‐responsive plasmonic nanoparticles with reversible optical properties based on protein‐coated gold nanoparticles grafted with thermosensitive polymer brushes by means of surface‐initiated atom transfer radical polymerization (SI‐ATRP) that exhibit pH‐dependent thermo‐responsive behavior. Spherical gold NPs of two different sizes (15 nm and 60 nm) and with different stabilizing agents (citrate and cetyltrimethylammonium bromide (CTAB), respectively) were first capped with bovine serum albumin (BSA). The resulting BSA‐capped NPs (Au@BSA NPs) exhibited not only extremely high colloidal stability under physiological conditions, but also a reversible U‐shaped pH‐responsive behavior, similar to pure BSA. The ϵ‐amine of the L‐lysine in the protein coating was then used to covalently bind an ATRP‐initiator, allowing for the SI‐ATRP of thermosensitive polymer brushes of oligo(ethylene glycol) methacrylates with an LCST of 42 °C in pure water and around 37 °C under physiological conditions. Such protein coated nanoparticles grafted with thermosensitive polymers exhibit a smart pH‐dependent thermosensitive behavior.
Auf der Suche nach neuen Materialien: Kristallzucht von quaternären und höherwertigen Oxiden in Flussmitteln
Authors: Bugaris Daniel E. , zur Loye Hans‐Conrad
Published: January 2012

Dieser Aufsatz behandelt die explorative Kristallzucht in Hochtemperaturlösungen als eine Methode zur Entdeckung von komplexen Oxidmaterialien. Er gibt eine Übersicht über das Verfahren der Kristallzucht in der Schmelze (Flux‐ oder Flussmittelzüchtung) und kann als Leitfaden für die Anwendung dieser Technik dienen. Die am häufigsten eingesetzten Schmelzen werden hinsichtlich ihres Lösungsvermögens für spezifische Elemente diskutiert, und typische Reaktionsbedingungen werden zusammengestellt. Um das Leistungsvermögen der Fluxmethode zu demonstrieren, werden verschiedene kürzlich hergestellte quaternäre und höhere Oxide vorgestellt, die für das Züchten von Oxidkristallen aus spezifischen Elementen geeignet sind.
Single, binary and ternary metal adsorption using acid‐treated Aegle marmelos Correa shell: kinetic, mechanistic and thermodynamic study
Authors: Anandkumar J. , Mandal B.
Published: January 2012

In this study, adsorption of metals from aqueous solution using H2SO4‐treated Aegle marmelos Correa shell (AMCS) was carried out in single and multimetal system. The maximum BET surface area (34.28 m2/g) and conspicuous change in the adsorbent surface were achieved when absolute concentration (98%) of acid was used to activate the AMCS. The sorption capacity of Pb2+, Ni2+ and Sr2+ was increased from 21.48 to 81.6 mg/g, 6.37 to 52.89 mg/g and 19.57 to 69.95 mg/g, respectively, as the H2SO4 concentration increased from 24.5% to 98% to activate the AMCS. The maximum adsorption capacities of Pb2+, Ni2+ and Sr2+ were observed at pH 5.2 (82.9 mg/g), 5.8 (54.89 mg/g) and 6.8 (72.95 mg/g), respectively. Presence of other ions significantly reduces the metal uptake when they were present at high concentrations in the metal solution. The equilibrium data fitted satisfactorily with Langmuir model compared with other models. Monolayer sorption capacity was obtained as 122.7, 70.18 and 80.73 mg/g for Pb2+, Ni2+ and Sr2+ at 30 °C, respectively. The effect of binary and ternary metal ions on adsorption capacity was found to be antagonistic behavior. The sorption kinetics was found to follow the pseudo‐second‐order kinetic model. But, the positive values of ΔH° and the increase in metal uptake with increase in solution temperature indicate the endothermic reaction for Ni2+ adsorption. The intermolecular binding (ion–dipole) of Pb2+ and Sr2+ and intermolecular binding coupled with intramolecular binding of Ni2+ were responsible for metal binding with cellulosic and lignin function groups. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.
Response Surface Methodology, an effective strategy in the optimization of the generation of curcumin‐loaded micelles
Authors: Wei Tan Khang , Manickam Sivakumar
Published: January 2012

Curcumin, a yellow pigment extracted from the dried rhizome of Curcuma longa, found to have significant pharmaceutical activities. However, the bioavailability of curcumin after administration is always low because of its extremely poor solubility in water. To improve the absorption rate of curcumin in vivo, curcumin‐loaded micelles have been developed by using GRAS surfactants, namely Brij 56 and Span 20, and by the application of ultrasonic cavitation. To investigate the interaction between different factors and to optimize the formulation conditions, Response Surface Methodology has been adopted. Both Central Composite Design and Box–Behnken Design (BBD) have been attempted in this study, and a better fitted quadric polynomial equation has been obtained from BBD that resulted into the coefficient of determination (R2) of 0.9894 and 0.9574 for the zeta‐average and polydispersity index of the formulation, respectively. In contrast, Analysis of Variance suggested a coefficient of determination (R2) for Central Composite Design plots that is 0.9172 for particle size response surface and 0.8246 for the polydispersity response surface. Optimization based on BBD model suggested 28 possible solutions, for which the generated solution with the highest desirability (0.764) predicted the curcumin‐loaded micelle formulation with 19.99 nm particle size and with 0.267 polydispersity index, when the formulation hydrophilic–lipophilic balance number is 9.46, curcumin‐to‐water weight ratio is 0.7 and surfactant‐to‐water weight ratio is 0.11. The whole investigation clearly supports the potential of ultrasonic cavitation in the generation of curcumin‐loaded micelles. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.
Present and future climate change in the semi‐arid region of West Africa: a crucial input for practical adaptation in agriculture
Authors: Sarr Benoît
Published: January 2012

Climate change trends and projections based on observation and climate models were reviewed in West Africa (WA). Historically, the region has experienced decades of severe drought along with cycles of above average rainfall which have greatly affected agricultural production. Future projections indicate decreased rainfall over the Sahel coastline. Observations already indicate an average increase in temperature of between 0.2 and 0.8 °C; when projected, this increases further to between 3.0 and 4.0 °C. Of greater concern, however, is the late onset, early cessation dates of rainfall and reduction of length of growing period (LGP) which are now locally negatively impacting agriculture in the region. Furthermore, projections indicate a 20% reduction of LGP in 2050. These results represent essential input for accelerating agricultural adaptation to climate change. Copyright © 2012 Royal Meteorological Society
Visualizing and quantifying cell phenotype using soft X‐ray tomography
Authors: McDermott Gerry , Fox Douglas M. , Epperly Lindsay , Wetzler Modi , Barron Annelise E. , Le Gros Mark A. , Larabell Carolyn A.
Published: January 2012

Soft X‐ray tomography (SXT) is an imaging technique capable of characterizing and quantifying the structural phenotype of cells. In particular, SXT is used to visualize the internal architecture of fully hydrated, intact eukaryotic and prokaryotic cells at high spatial resolution (50 nm or better). Image contrast in SXT is derived from the biochemical composition of the cell, and obtained without the need to use potentially damaging contrast‐enhancing agents, such as heavy metals. The cells are simply cryopreserved prior to imaging, and are therefore imaged in a near‐native state. As a complement to structural imaging by SXT, the same specimen can now be imaged by correlated cryo‐light microscopy. By combining data from these two modalities specific molecules can be localized directly within the framework of a high‐resolution, three‐dimensional reconstruction of the cell. This combination of data types allows sophisticated analyses to be carried out on the impact of environmental and/or genetic factors on cell phenotypes.
Spectrofluorimetric determination of aliskiren in dosage forms and urine
Authors: Aydoğmuş Zeynep
Published: January 2012

A new, simple and sensitive spectrofluorimetric method has been developed for the determination of aliskiren (ALS) in dosage forms and human urine. The method is based on the reaction between ALS and fluorescamine in borate buffer solution, pH 9, to give a highly fluorescent derivative which is measured at 482 nm after excitation at 382 nm. The factors affecting the reaction were carefully studied. The fluorescence intensity concentration plots were rectilinear over the range 140–1400 ng/mL with a limit of detection 13.47 ng/mL and limit of quantitation 40.81 ng/mL. The developed method was successfully applied to the analysis of the drug in tablets and human urine; the average recoveries (n = 6) were 99.88 ± 0.38% and 99.57 ± 0.44%, respectively. The analytical performance of the method was fully validated and the results were satisfactory. The stability of the drug was studied by subjecting it to acidic, basic, oxidative and thermal degradation. Copyright © 2012 John Wiley & Sons, Ltd.
Application of optimized chemiluminescence assay for determination of the antioxidant capacity of herbal extracts
Authors: Pogačnik Lea , Ulrih Nataša Poklar
Published: January 2012

A chemiluminescence (CL) assay for the determination of antioxidant capacity (AOC) has been optimized and applied to analyses of herbal extracts in the present study. The optimal concentrations of reagents (luminol, H2O2, horseradish peroxidase) have been determined, as well as the optimal reaction conditions (wavelength, pH, temperature, sample volume). All of the measurements were performed at the emission maximum of the oxidized form of luminol (425 nm). The optimal concentrations of the reagents were determined as follows: 1.6 mmol/L luminol, 7.5 mmol/L H2O2 and 0.14 U/mL horseradish peroxidase activity in the reaction mixture. Analyses were carried out in phosphate buffer, pH 7.4, at room temperature. With the optimized CL assay, the AOCs of various water and methanol herbal extracts were determined (dog rose hips, plantain leaves and coltsfoot and thyme flowers) and the results were compared to those obtained by other classical methods for the evaluation of antioxidants. Strong correlations (r > 0.9) with the Folin–Ciocalteau assay and the 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH)● assay are confirmed, although there is no correlation between AOC and the concentration of ascorbic acid in the samples analysed. This optimized CL assay is simple, rapid and reliable, and it represents a good alternative to classical methods (Folin–Ciocalteau, DPPH●) for the determination of AOC of herbal extracts and other food samples. Copyright © 2012 John Wiley & Sons, Ltd.
Adipokines, an adipose tissue and placental product with biological functions during pregnancy
Authors: D'Ippolito Silvia , Tersigni Chiara , Scambia Giovanni , Di Simone Nicoletta
Published: January 2012

Latter half of pregnancy is characterized by a “physiological diabetogenic state” since changes in insulin‐sensitivity have been well documented. These changes ensure continuous supply of nutrients to the growing fetus. In the last years the role of adipocyte‐derived signaling molecules, collectively known as adipokines has been object of different in vitro and in vivo studies. Of interest, adipokines and/or their receptors are expressed in the placental tissue which, therefore, can contribute to development of maternal insulin‐resistance and, as a consequence, fetal growth. Leptin, adiponectin, and resistin represent the most well studied adipokines and, with the exception of adiponectin, their serum and placental levels increase as pregnancy progresses. High levels of adipokines have also been detected in umbilical plasma hence suggesting a possible role on fetal development and metabolism; however, it remains still unclear if such adipokines can directly stimulate fetal tissues development acting as growth factors. In addition to their well known metabolic effects, we also reported studies describing the role of adipokines in promoting proliferation and invasiveness of trophoblast cells and affecting local angiogenic processes. These observations strongly suggest that adipokines, by alternatively interfering with placental development, may affect pregnancy outcome and fetal growth. However, further studies are needed to better understand the local regulation of their expression. © 2012 International Union of Biochemistry and Molecular Biology, Inc.