bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of sea ice loss on sea salt aerosol concentrations and the radiative balance in the Arctic
Authors: Struthers H. , Ekman A. M. L. , Glantz P. , Iversen T. , Kirkevåg A. , Mårtensson E. M. , Seland Ø. , Nilsson E. D.
Published: April 2011

Abstract. Understanding Arctic climate change requires knowledge of both the external and the local drivers of Arctic climate as well as local feedbacks within the system. An Arctic feedback mechanism relating changes in sea ice extent to an alteration of the emission of sea salt aerosol and the consequent change in radiative balance is examined. A set of idealized climate model simulations were performed to quantify the radiative effects of changes in sea salt aerosol emissions induced by prescribed changes in sea ice extent. The model was forced using sea ice concentrations consistent with present day conditions and projections of sea ice extent for 2100. Sea salt aerosol emissions increase in response to a decrease in sea ice, the model results showing an annual average increase in number emission over the polar cap (70–90° N) of 86 × 106 m−2 s−1 (mass emission increase of 23 μg m−2 s−1). This in turn leads to an increase in the natural aerosol optical depth of approximately 23%. In response to changes in aerosol optical depth, the natural component of the aerosol direct forcing over the Arctic polar cap is estimated to be between −0.2 and −0.4 W m−2 for the summer months, which results in a negative feedback on the system. The model predicts that the change in first indirect aerosol effect (cloud albedo effect) is approximately a factor of ten greater than the change in direct aerosol forcing although this result is highly uncertain due to the crude representation of Arctic clouds and aerosol-cloud interactions in the model. This study shows that both the natural aerosol direct and first indirect effects are strongly dependent on the surface albedo, highlighting the strong coupling between sea ice, aerosols, Arctic clouds and their radiative effects.
Diurnal variations of residential particulate wood burning emissions and their contribution to the concentration of Polycyclic Aromatic Hydrocarbons (PAHs)
Authors: Poulain L. , Iinuma Y. , Müller K. , Birmili W. , Weinhold K. , Brüggemann E. , Gnauk T. , Hausmann A. , Löschau G. , Wiedensohler A. , Herrmann H.
Published: April 2011

Abstract. Residential wood burning is becoming an increasingly important cause of air quality problems since it has become a popular source of alternative energy to fossil fuel. In order to characterize the contribution of residential wood burning to local particle pollution a field campaign was organized at the village of Seiffen (Saxony, Germany). During this campaign, an Aerosol Mass Spectrometer (AMS) was deployed in parallel to a PM1 high volume filter sampler. The AMS mass spectra were analyzed using Positive Matrix Factorization (PMF) to obtain detailed information about the organic aerosol (OA). Biomass-burning organic aerosol (BBOA), Hydrocarbon-like organic aerosol (HOA), Low-volatility oxygenated organic aerosol (LV-OOA) and Semi-volatile oxygenated organic aerosol (SV-OOA) were identified. Additionally, Polycyclic Aromatic Hydrocarbons (PAH) were measured by the AMS and short term events of extremely high PAH concentration compared to the mean PAH value were observed during the whole measurement period. A comparison with the results from PM1 filter samples showed that the BBOA factor and the AMS PAH are good indicators of the total concentration of the different monosaccharide anhydrides and PAH measured on the filter samples. Based on its correlation with CO and the low car traffic, the HOA factor was considered to be related to residential heating using liquid fuel. A clear impact of the week and weekend days on the diurnal profiles of the different OA components was observed. The weekdays were characterized by two maxima; a first one early in the morning and a stronger one in the evening; during the weekend days, the different OA components principally reached one maxima early in the afternoon. Finally, the PAH emitted directly from residential wood combustion was estimated to represent 1.5% of the total mass of BBOA factor and around 62% of the total PAH concentration measured at Seiffen. This result highlights the important contribution of residential wood combustion to air quality and PAH emissions at the sampling place which might have a significant impact on human health. Moreover, it also emphasizes the need for a better time resolution of the chemical characterization of toxic particulate compounds in order to provide more information about variations of the different sources through the days as well as to better estimate the real human exposure.
Glacial marine carbon cycle sensitivities to Atlantic ocean circulation reorganization by coupled climate model simulations
Authors: Chikamoto M. O. , Abe-Ouchi A. , Oka A. , Ohgaito R. , Timmermann A.
Published: April 2011

Abstract. A series of Last Glacial Maximum (LGM) marine carbon cycle sensitivity experiments is conducted to test the effect of different physical processes, as simulated by two atmosphere-ocean general circulation model (AOGCM) experiments, on the atmospheric pCO2. One AOGCM solution exhibits an increase in North Atlantic Deep Water (NADW) formation, whereas the other mimics an increase in Antarctic Bottom Water (AABW) associated with a weaker NADW. Due to enhanced gas solubility associated with lower sea surface temperature, both experiments generate a reduction of atmospheric pCO2 by about 20–23 ppm. However, neither a weakening of NADW nor an increase of AABW formation causes a large atmospheric pCO2 change. A marked enhancement in AABW formation is required to represent the reconstructed vertical gradient of dissolved inorganic carbon (DIC) during LGM conditions. The efficiency of Southern Ocean nutrient utilization reduces in response to an enhanced AABW formation, which counteracts the circulation-induced ocean carbon uptake.
Data assimilation using a hybrid ice flow model
Authors: Goldberg D. N. , Sergienko O. V.
Published: April 2011

Abstract. Hybrid models, or depth-integrated flow models that include the effect of both longitudinal stresses and vertical shearing, are becoming more prevalent in dynamical ice modeling. Under a wide range of conditions they closely approximate the well-known First Order stress balance, yet are of computationally lower dimension, and thus require less intensive resources. Concomitant with the development and use of these models is the need to perform inversions of observed data. Here, an inverse control method is extended to use a hybrid flow model as a forward model. We derive an adjoint of a hybrid model and use it for inversion of ice-stream basal traction from observed surface velocities. A novel aspect of the adjoint derivation is a retention of non-linearities in Glen's flow law. Experiments show that in some cases, including those nonlinearities is advantageous in minimization of the cost function, yielding a more efficient inversion procedure.
SD-OCT Pattern of Retinal Venous Occlusion with Cystoid Macular Edema Treated with Ozurdex®
Authors: Coscas Gabriel , Coscas Florence , Zucchiatti Ilaria , lacet-Bernard Agnes G , Soubrane Gisele , Souïed Eric
Published: April 2011

Purpose

To report our experience with sustained-release dexamethasone 0.7 mg intravitreal implant (Ozurdex®; Allergan, Inc., Irvine, CA) in retinal vein occlusion with macular edema.

Methods

A prospective study of a series of 9 patients with recent retinal vein occlusion with macular edema treated with sustained-release dexamethasone 0.7 mg intravitreal implant was performed. Complete ophthalmic examination including visual acuity, fundus biomicroscopy, fundus photography, fluorescein angiography, and spectral domain optical coherence tomography (Spectralis SD-OCT; Heidelberg Engineering, Heidelberg, Germany) was performed at baseline and follow-up (1 week, 1 month, and 3 months), and tolerability of the implant was assessed.

Results

Nine eyes of 9 consecutive patients treated with a total of 9 sustained-release dexamethasone 0.7 mg intravitreal implants for macular edema associated with retinal vein occlusion were included. Five patients had central retinal vein occlusion and 4 patients had branch retinal vein occlusion. Accentuated ischemia was associated in 2/5 patients with central retinal vein occlusion. All eyes showed SD-OCT evidence of decreased edema following implant placement (mean decrease in central retinal thickness 320 μm). All eyes showed decrease of serous detachment of the neurosensory retina (not present in 7/9 cases at 1 month). Intraretinal central cyst resolved in 7/9 cases; small peripheral cysts were persistent in only 2/9 cases. Spectral domain optical coherence tomography demonstrated the presence and the integrity of external limiting membrane and inner and outer segments (IS/OS) of the photoreceptors in 6/9 cases at month 3. Forty percent of patients gained ≥10 letters of best-corrected visual acuity at 3 months. The safety profile was consistent with the results of a previous phase III trial of Ozurdex®, and no serious ocular or systemic adverse events were observed during the follow-up period.

Conclusions

In patients with macular edema in retinal vein occlusion, sustained-release dexamethasone 0.7 mg intravitreal implant may be an effective treatment option to control macular edema. At the final visit, foveal thickness was decreased to physiologic levels in all eyes. In parallel with resolution of the macular edema, visual acuity was significantly improved at the final visit. However, final visual acuity in eyes with still interrupted or thickened IS/OS interface was significantly poorer than that in eyes with a normal IS/OS line.
Remission and Dropout Rate of Anti-VEGF Therapy for Age-Related Macular Degeneration
Authors: Oishi Akio , Mandai Michiko , Nishida Akihiro , Hata Masayuki , Matsuki Takaaki , Kurimoto Yasuo
Published: April 2011

Purpose.

Anti-vascular endothelial growth factor (VEGF) therapy is a first-line treatment for age-related macular degeneration (AMD) but frequent visits and injections can be a burden for patients. The purpose of this study is to estimate the remission rate and tolerability of anti-VEGF therapy for AMD in a clinical setting.

Methods.

We investigated 90 eyes of 87 patients with AMD who underwent anti-VEGF therapy and were followed for more than 6 months. Ranibizumab and pegaptanib were used as anti-VEGF agents. Initial therapy was any of the following: a single injection, 3 consecutive monthly injections, or combination therapy with verteporfin. Additional injections were given as-needed during follow-up. An injection-free period greater than 6 months at the final observation was regarded as cessation; the reason for cessation was studied for each patient. Clinical characteristics were compared between patents with and without cessation.

Results.

The mean follow-up period was 12.8 months. Mean logMAR before and 6 months after the treatment was 0.89 and 0.83, respectively. Cessation was noted in 32 eyes of 31 patients (35.6%). Remission was achieved in 13 (40.6%) of these eyes. The other cases either did not wish to undergo further treatment or dropped out. Poor baseline visual acuity (VA) was associated with cessation.

Conclusions.

With current anti-VEGF therapy, remission was achieved in a limited number of AMD cases. The high frequency of voluntary cessation warrants consideration of an alternative treatment and/or supportive care for those with poor baseline VA.
Benthic Ecology of Bahia de San Quintin, Baja California
Authors: Barnard J. Laurens
Published: April 2011

Three important biotic assemblages and several minor associations occur on the soft bottoms of San Quintin Bay. The most obvious assemblage is characterized by the eelgrass, Zostera marina, that covers approximately 20 percent of the study area. A second densely populated assemblage occurs in tidal channels and on their margins and is dominated by a globular ascidian, Eugyra glutinans, and a tube-forming amphipod, Ampelisca compressa. That community merges with a poorly populated Prionospio (polychaete) community occupying sand flats in shallow, quiet water; the two are asymmetrically connected by a facies (or ecotone) characterized especially by two genera of amphipods, Acuminodeutopus and Rudilemboides. A less widespread fourth assemblage, dominated by a polychaete genus Fabricia, occurs primarily adjacent to marshes, especially in the inner reaches of the lagoon. Three phases of the Prionospio community occur, the typical phase and phases dominated by the polychaetes Scoloplos acmeceps and Cossura Candida. The Ampelisca-Eugyra community also exists in extreme phases dominated by either of the principal members. The Prionospio community is interpreted as a base community representing a penetration from the open sea of an analogous community in shallow waters on which is imposed the Zostera community where suitable banks are elevated above the surrounding fiats. The Zostera community has few elements in common with the Phyllospadix (surfgrass) community of the open sea. The Eugyra-Ampelisca community occurs mainly in channels and at the feet of banks where water motion is highest in the bay. The Eugyra-Ampelisca community is unique to the literature but has affinities with open-sea Tellina communities. San Quintin has few of the cosmopolitan taxa usually introduced into bays by humans. The warm-temperate lagoons of California and Baja California have few common denominators probably because of changes imposed by man. Very few species in San Quintin are obligatory inhabitants of lagoons. San Quintin is unusual in being controlled physiographically by cinder cones; the west arm is a typical lagoon, whereas the east arm has characteristics of a drowned river valley. A hypothetical system of lagoonal maturation and senescence is proposed in which the depositional influences are accelerated by soft-bodied benthic biota.
Overview on the Use of NMR to Examine Protein Structure
Authors: Breukels Vincent , Konijnenberg Albert , Nabuurs Sanne M. , Doreleijers Jurgen F. , Kovalevskaya Nadezda V. , Vuister Geerten W.
Published: April 2011

Any protein structure determination process contains several steps, starting from obtaining a suitable sample, then moving on to acquiring data and spectral assignment, and lastly to the final steps of structure determination and validation. This unit describes all of these steps, starting with the basic physical principles behind NMR and some of the most commonly measured and observed phenomena such as chemical shift, scalar and residual coupling, and the nuclear Overhauser effect. Then, in somewhat more detail, the process of spectral assignment and structure elucidation is explained. Furthermore, the use of NMR to study protein‐ligand interaction, protein dynamics, or protein folding is described. Curr. Protoc. Protein Sci. 64:17.5.1‐17.5.44. © 2011 by John Wiley & Sons, Inc.
Tailoring the Separation Behavior of Hybrid Organosilica Membranes by Adjusting the Structure of the Organic Bridging Group
Authors: Castricum Hessel L. , Paradis Goulven G. , Mittelmeijer‐Hazeleger Marjo C. , Kreiter Robert , Vente Jaap F. , ten Elshof Johan E.
Published: April 2011

Hybrid organically linked silica is a highly promising class of materials for the application in energy‐efficient molecular separation membranes. Its high stability allows operation under aggressive working conditions. Herein is reported the tailoring of the separation performance of these hybrid silica membranes by adjusting the size, flexibility, shape, and electronic structure of the organic bridging group. A single generic procedure is applied to synthesize nanoporous membranes from bridged silsesquioxane precursors with different reactivities. Membranes with short alkylene (CH2 and C2H4) bridging groups show high H2/N2 permeance ratios, related to differences in molecular size. The highest CO2/H2 permeance ratios, related to the affinity of adsorption in the material, are obtained for longer (C8H16) alkylene and aryl bridges. Materials with long flexible alkylene bridges have a hydrophobic surface and show strongly temperature‐dependent molecular transport as well as a high n‐butanol flux in a pervaporation process, which is indicative of organic polymerlike properties. The versatility of the bridging group offers an extensive toolbox to tune the nanostructure and the affinity of hybrid silica membranes and by doing so to optimize the performance towards specific separation challenges. This provides excellent prospects for industrial applications such as carbon capture and biofuel production.
A Pyridine‐Containing Anthracene Derivative with High Electron and Hole Mobilities for Highly Efficient and Stable Fluorescent Organic Light‐Emitting Diodes
Authors: Sun Yongduo , Duan Lian , Zhang Deqiang , Qiao Juan , Dong Guifang , Wang Liduo , Qiu Yong
Published: April 2011

A pyridine‐containing anthracene derivative, 9,10‐bis(3‐(pyridin‐3‐yl)phenyl)anthracene (DPyPA), which comprehensively outperforms the widely used electron‐transport material (ETM), tris(8‐quinolinolato) aluminum (Alq3), is synthesized. DPyPA exhibits ambipolar transport properties, with both electron and hole mobilities of around 10−3 cm−2 V−1 s−1; about two orders of magnitude higher than that of Alq3. The nitrogen atom in the pyridine ring of DPyPA coordinates to lithium cations, which leads to efficient electron injection when LiF/Al is used as the cathode. Electrochemical measurements demonstrate that both the cations and anions of DPyPA are stable, which may improve the stability of devices based on DPyPA. Red‐emitting, green‐emitting, and blue‐emitting fluorescent organic light emitting diodes with DPyPA as the ETM display lower turn‐on voltages, higher efficiencies, and stronger luminance than the devices with Alq3 as the ETM. The power efficiencies of the devices based on DPyPA are greater by 80–140% relative to those of the Alq3‐based devices. The improved performance of these devices is attributed to the increased carrier balance. In addition, the device employing DPyPA as the ETM possesses excellent stability: the half‐life of the DPyPA‐based device is 67 000 h—seven times longer than that of the Alq3‐based device—for an initial luminance of 5000 cd m−2.
Simple and Efficient Copper(I)‐Catalyzed Access to Three Versatile Aminocoumarin‐Based Scaffolds using Isocyanoacetate
Authors: Meng Tao , Zou Yiquan , Khorev Oleg , Jin Yu , Zhou Huayong , Zhang Yongliang , Hu Dingyu , Ma Lanping , Wang Xin , Shen Jingkang
Published: April 2011

An efficient method has been developed for the one‐pot copper(I)‐catalyzed synthesis of 3‐aminocoumarin and its derivatives, such as 3‐substituted methylideneaminocoumarins and chromeno[3,4‐d]imidazol‐4(1H)‐ones. Significantly, the strategy presents a straightforward and efficient approach to constructing biologically useful molecular scaffolds.
Access to 2‐Aminopyridines – Compounds of Great Biological and Chemical Significance
Authors: Bolliger Jeanne L. , Oberholzer Miriam , Frech Christian M.
Published: April 2011

2‐Aminopyridines are key structural cores of bioactive natural products, medicinally important compounds, and organic materials and thus, extremely valuable synthetic targets. The few reported 6‐substituted 2‐aminopyridines and the lack of flexible, efficient and general applicable methods for their synthesis demonstrates the urgent need of new methods for their preparation. Reactions between 2,6‐dibromopyridine and primary or secondary, cyclic or acyclic, and aliphatic or aromatic amines were shown to selectively yield the respective 6‐bromopyridine‐2‐amines in very high yields which were successfully used as substrates for subsequent CC cross‐coupling reactions. The recently introduced dichloro‐bis[1‐(dicyclohexylphosphanyl)piperidine]palladium (1) was used as catalyst for the cross‐coupling of 6‐bromopyridine‐2‐amines with arylboronic acids, diaryl‐ and dialkylzinc reagents or olefins and hence, is also an excellent CC cross‐coupling catalyst for this type of substrate. Moreover, all the reaction protocols presented were in each of the catalyses uniformly applied. The scope of both the amination and the cross‐coupling reactions are well defined and allow one to simply adapt the reaction protocols directly to other amines and/or coupling partners and, thus, provide for the first time a very flexible and generally applicable reaction protocol to get access to 2‐aminopyridines.
Fellowship training in rhinology: American Rhinologic Society survey of U.S. graduates
Authors: Batra Pete S. , Kingdom Todd T. , Citardi Martin J. ,   for the American Rhinologic Society Fellowship Committee
Published: April 2011

Background:

The past 5 years have witnessed the introduction of numerous rhinology fellowships that may have altered the education of individuals electing to pursue postgraduate training. The objective of this study was to evaluate the rhinology fellowship experience and its possible impact on current practice patterns of U.S. fellowship‐trained rhinologists.

Methods:

A 27‐item web‐based survey (www.surveymonkey.com) was conducted under the purview of the American Rhinologic Society (ARS) Fellowship Committee between November 2009 and January 2010. The target group included 112 rhinologists who completed fellowship training between 1990 and 2009.

Results:

A total of 62 fellows (55.4%) completed the survey. The respondents represented all regions of the country, with most common being southeast (25%) and south central (18%). The most common type of clinical practice was academic in 68%, followed by single‐specialty group (19%), multispecialty (6.5%), and solo practice (6.5%). Rhinology entailed >75% and 50% to 75% of clinical practice for 61% and 24% of respondents, respectively. The primary reasons for selecting a rhinology fellowship were career in academics (64%) and interest in rhinologic procedures (31%). Overall fellowship experience was rated as excellent and good by 84% and 16%, respectively. The mean number of rhinologic procedures during fellowship were >200 in 59% and 151 to 200 in 27% of respondents. Allergy training exposure was reported by 59% during training. Clinical and basic science research exposure was rated as excellent or good by 90% and 44%, respectively.

Conclusion:

The rhinology fellowship experience to date appears to be well‐regarded by majority of respondents. Future dialogue should focus on identification of deficiencies in the current rhinology fellowship educational process. © 2011 ARS‐AAOA, LLC.
Expanded Porphyrins: Intriguing Structures, Electronic Properties, and Reactivities
Authors: Saito Shohei , Osuka Atsuhiro
Published: April 2011

The chemistry of expanded porphyrins, which are higher homologues of porphyrins, has been intensively explored for the last three decades. Expanded porphyrins exhibit structures, electronic properties, coordination chemistry, and reactivities that are entirely different from those of porphyrins. Through these studies, it has become increasingly apparent that expanded porphyrins are attractive in views of aromaticity and multimetal coordination, or as functional dyes, nonlinear optical materials, ion receptors, or stable organic radicals. As such, we have continuously witnessed the emergence of expanded porphyrins that exhibit unprecedented structures and properties, as is highlighted by the facile realization of Möbius aromatic and even antiaromatic systems with twisted molecular structures. In this Review, the recent progress of the chemistry of expanded porphyrins after the seminal Review by Sessler and Seidel in 2003 is presented.
Determining the elastic properties of modified polystyrenes by sound velocity measurements
Authors: Oral Imran , Guzel Hatice , Ahmetli Gulnare , Gur C. Hakan
Published: April 2011

The effect of the binding of various polyfunctional groups to polystyrene's (PS's) aromatic ring on the elastic properties of the PS were investigated by an ultrasonic method. Various sets of samples were prepared by chemical modification of pure PSs having different molecular weights with SA, maleic anhydride, and phthalic anhydride. The ultrasonic wave velocities of modified PSs were measured with the pulse‐echo method at room temperature by a computer‐controlled analyzer and a digital oscilloscope. The values of the acoustic impedance, Poisson's ratio, and elasticity constants of the samples were calculated by the measured values of the densities and sound velocities. The longitudinal and shear wave velocities and the values of all elastic constants increased with chemical modification of the pure PS. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Clozapine recognition via molecularly imprinted polymers; bulk polymerization versus precipitation method
Authors: Mohajeri Seyed Ahmad , Karimi Gholamreza , Aghamohammadian Javad , Khansari Mehdi Rajabnia
Published: April 2011

Two clozapine (CLZ) imprinted polymers were prepared by bulk and precipitation methods. Methacrylic acid and ethylene glycol dimethacrylate (EDMA) were used as functional and crosslinker monomers, respectively. The mean diameter and particle size distribution of the imprinted (P‐MIP) and nonimprinted (P‐NIP) particles obtained in precipitation method were examined. A conventional batch‐adsorption test was applied for characterization of CLZ–polymer interaction. Dissociation constant (KD) and maximum binding sites (Bmax) were calculated using Scatchard analysis. To evaluate the recognition properties of polymers, phenytoin (PTN) binding to each polymer was also studied and compared to CLZ. The imprinting factor (IF) and selectivity factor (α) were also determined for each polymer. Average diameter and polydispersity of P‐MIP were 925 nm and 0.17, respectively. The data for P‐NIP were 1.05 μm and 0.18. The KD, IF, and α values calculated for P‐MIP were 0.45 μM, 3.26, and 17.43, respectively. The data for imprinted polymer, prepared by bulk polymerization (B‐MIP), were 14.5 μM, 1.95, and 3.67. These results demonstrated that precipitation polymerization is a more convenient, more effective, and more reproducible method than bulk polymerization for the synthesis of uniformly sized micron and submicron‐imprinted polymer particles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Tailoring the surface of magnetic microparticles for protein immobilization
Authors: Reichelt Senta , Elsner Christian , Pender Alya , Buchmeiser Michael R.
Published: April 2011

Magnetic, amine‐functionalized microparticles (dynabeads®) were surface‐modified with different polyamines to suppress the nonspecific protein adsorption to a maximum extent but to allow for the enhanced covalent attachment of selected biomolecules (proteins). The stepwise chemical modification entailed the consecutive reaction of amine‐functionalized dynabeads® with glutaric dialdehyde (GA) followed by the reaction with multifunctional, amine‐containing compounds such as poly(allyl amine), poly(ethylene imine), and bovine serum albumin. The model proteins trypsin and concanavalin A, respectively, were finally covalently bound to the polyamine‐functionalized dynabeads via GA‐mediated coupling. Matrix‐assisted laser‐desorption/ionization time of flight/time of flight mass spectrometry confirmed the successful protein attachment. Both the nonspecific protein adsorption to the different polyamine‐modified surfaces and the GA‐mediated covalent binding of the target proteins to the polyamine‐functionalized surfaces was quantified by standard bioassays. Compared to unmodified beads, the bioactivity of the polyamine‐functionalized ones was increased by a factor of seven while keeping the nonspecific protein adsorption of a selected cationic protein at a very low level. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Guanidinylation: A simple way to fabricate cell penetrating peptide analogue‐modified chitosan vector for enhanced gene delivery
Authors: Zhai Xinyun , Sun Peng , Luo Yongfeng , Ma Chaonan , Xu Jun , Liu Wenguang
Published: April 2011

In view of the analogous transmembrane function to cell penetrating peptides, guanidine group was incorporated into chitosan by chemical modification to enhance the transfection performance of chitosan vectors. Guanidinylated chitosan (GCS) was shown to be well soluble in neutral aqueous solution. The interaction between GCS with plasmid DNA was characterized by agarose retardation experiment and ethidium bromide displacement assay. GCS formed more stable complexes with DNA under physiological pH than chitosan. The transfection efficiency of GCS was evaluated employing COS‐7 cell line—GCS polyplexes demonstrated higher transfection efficiency and lower cytotoxicity relative to chitosan. The optimum efficiency of GCS was achieved in the vicinity of the critical complexing ratio. The results of flow cytometry indicated that guanidinylation promoted an eightfold increase in the cell uptake. The study revealed that guanidinylated chitosan is a promising candidate as an effective nonviral vector for in vivo gene delivery. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis and characterization of organo‐soluble poly(ether ether ketone)s and poly(ether ether ketone ketone)s containing pendant pentadecyl chains
Authors: More Arvind S. , Pasale Sharad K. , Honkhambe Pandurang N. , Wadgaonkar Prakash P.
Published: April 2011

Poly(ether ether ketone)s and poly(ether ether ketone ketone)s containing pendant pentadecyl chains were synthesized by polycondensation of each of the two bisphenol monomers viz, 1,1,1‐[bis(4‐hydroxyphenyl)‐4′‐pentadecylphenyl]ethane and 1,1‐bis(4‐hydroxyphenyl)‐3‐pentadecyl cyclohexane with activated aromatic dihalides namely, 4,4′‐difluorobenzophenone, and 1,3‐bis(4‐fluorobenzoyl)benzene in a solvent mixture of N,N‐dimethylacetamide and toluene, in the presence of anhydrous potassium carbonate. Polymers were isolated as white fibrous materials with inherent viscosities and number average molecular weights in the range 0.70–1.27 dL g−1 and 76,620–1,36,720, respectively. Poly(ether ether ketone)s and poly(ether ether ketone ketone)s were found to be soluble at room temperature in organic solvents such as chloroform, dichloromethane, tetrahydrofuran, and pyridine and could be cast into tough, transparent, and flexible films from their solutions in chloroform. Wide angle X‐ray diffraction patterns exhibited a broad halo at around 2θ = ∼ 19° indicating that the polymers containing pentadecyl chains were amorphous in nature. In the small‐angle region, diffuse reflections of a typically layered structures resulting from the packing of pentadecyl side chains were observed. The temperature at 10% weight loss, obtained from TG curves, for poly(ether ether ketone)s and poly(ether ether ketone ketone)s were in the range 416–459°C, indicating their good thermal stability. A substantial drop in glass transition temperatures (68–78°C) was observed for poly(ether ether ketone)s and poly(ether ether ketone ketone)s due to “internal plasticization” effect of flexible pendant pentadecyl chains. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Conservation of Mediterranean habitats and biodiversity countdowns: what information do we really need?
Authors: Fraschetti Simonetta , Guarnieri Giuseppe , Bevilacqua Stanislao , Terlizzi Antonio , Claudet Joachim , Russo Giovanni Fulvio , Boero Ferdinando
Published: April 2011

The relentless increase in both human activities and exploitation of marine resources is a threat to marine habitats and species.

For marine systems, several protection initiatives have been outlined over the past decade to significantly reduce the current rate of biodiversity loss at global, regional, and national levels, and to establish representative networks of marine protected areas with the aim of protecting 10–30% of marine habitats.

Reliable estimates of the total area occupied by each habitat are crucial to set adequate protection initiatives. Habitat mapping requires a sound habitat classification. Many classification schemes have been developed in different areas of the world, sometimes based on questionable criteria.

A critical analysis of the most recent marine habitat classification list produced for the Mediterranean Sea from the Regional Activity Centre for Specially Protected Areas (RAC/SPA) showed that (i) 39% of habitats and associated species considered in the list are scarcely covered by scientific knowledge from Web‐based resources; (ii) 62% of the species/genera included in the list are primary producers; (iii) quantitative information about the geographical distribution of selected habitats and associated species is scant; and (iv) when available, information is largely unbalanced and biased towards the shallow western Mediterranean Sea.

Improved inventories of marine habitats are needed to support accurate and consistent mapping activities. The combination of large‐scale mapping and sound habitat classifications will allow better estimates of biodiversity distribution, to reverse regional/global habitat loss rates through the achievement of conservation targets and deadlines that, for the moment, are systematically not met. Copyright © 2011 John Wiley & Sons, Ltd.
Videogame preservation and massively multiplayer online role‐playing games: A review of the literature
Authors: Winget Megan A.
Published: April 2011

Videogames are important cultural and economic artifacts. They also present challenges that anticipate the problems inherent in any complex digital interactive system. Not only are they digital and hence very difficult to preserve but they also are software systems that have significant hardware, peripheral, and network dependencies, which are difficult to collect and formally represent. This article reviews the literature related to videogame preservation. In addition to covering the traditional technology‐related issues inherent in all digital preservation endeavors, this review also attempts to describe the complexities and relationships between the traditional acts of technology preservation, representation, and collection development. Future work should include the identification of important user groups, an examination of games' context of use, and the development of representational models to describe interaction of players with the game and the interactions between players playing the game.
Self‐Assembly of Lead Chalcogenide Nanocrystals
Authors: Quan Zewei , Valentin‐Bromberg Loriana , Loc Welley Siu , Fang Jiye
Published: April 2011

This review focuses on recent developments in the self‐assembly of lead chalcogenide nanocrystals into two‐ and three‐dimensional superstructures. Self‐assembly is categorized by the shapes of building blocks, including nanospheres, nanocubes, nano‐octahedra, and nanostars. In the section on nanospheres, rapid assemblies of lead chalcogenide‐based multicomponent nanocrystals with additional components, such as semiconductors, noble metals, and magnetic nanocrystals, are further highlighted. In situ self‐assembly of lead chalcogenide nanocrystals into one‐dimensional nanostructures at elevated temperatures is also covered. Each section of this paper highlights examples extracted from recent publications. Finally, relatively novel properties and applications arising from lead chalcogenide superlattices as typical examples are also discussed.
From Electron‐Reservoir Complexes to Dendritic Molecular Nanobatteries
Authors: Astruc Didier
Published: April 2011

In this review, which is mostly focused on the concepts and work developed in the author’s laboratory, the access and properties of electron‐reservoir (redox‐robust) transition‐metal complexes with sufficiently negative redox potentials and their branching to the tethers of dendrimers and other related nanodevices are highlighted, with the idea of designing dendritic molecular batteries.
Bifurcation search via feedback loop breaking in biochemical signaling pathways with time delay
Authors: Waldherr Steffen , Dylus David , Allgöwer Frank
Published: April 2011

We develop a method to locate bifurcations in time delay systems with a potentially high‐dimensional parameter space. It is based on the feedback loop breaking approach that we developed and applied earlier for bifurcation search in ordinary differential equations. The method is particularly suited for the analysis of biological networks, for example to determine which parameters are relevant for complex dynamical behavior in such networks. To illustrate the benefits that this approach yields for biological network analysis, we apply it to study the effect of parameter variations on oscillations in a model of the MAP kinase cascade with a time delay.

Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Stability‐indicating micelle‐enhanced spectrofluorimetric method for determination of loratadine and desloratadine in dosage forms
Authors: Walash M. I. , Belal F. , El‐Enany N. , Eid M. , El‐Shaheny R. N.
Published: April 2011

A highly sensitive and simple spectrofluorimetric method was developed for the determination of loratadine (LRT) and desloratadine (DSL) in their pharmaceutical formulations. The proposed method is based on investigation of the fluorescence spectral behaviour of LRT and DSL in a sodium dodecyl sulphate (SDS) micellar system. In aqueous solution of acetate buffer of pH 4.5, the fluorescence intensities of both LRT and DSL were greatly enhanced (240%) in the presence of SDS. The fluorescence intensity was measured at 438 nm after excitation at 290 nm for both drugs. The fluorescence–concentration plots were rectilinear over the range 0.05–2.0 µg/mL for both LRT and DSL, with lower detection limits of 5.13 × 10−3 and 6.35 × 10−3 µg/mL for LRT and DSL, respectively. The method was successfully applied to the analysis of the two drugs in their commercial tablets, capsules and syrups, and the results were in good agreement with those obtained with the official or comparison methods. The proposed method is specific for the determination of LRT in the presence of other co‐formulated drugs, such as pseudoephedrine. The application of the proposed method was extended to stability studies of LRT and DSL after exposure to different forced degradation conditions, such as acidic, alkaline and oxidative conditions, according to ICH guidelines. Copyright © 2011 John Wiley & Sons, Ltd.
Post‐translational protein modification by carotenoid cleavage products
Authors: Kalariya Nilesh M. , Ramana Kota V. , Srivastava Satish K. , van Kuijk Frederik J.G.M.
Published: April 2011

Carotenoids are known to generate various aldehydes, known as carotenoid‐derived aldehydes (CDAs), which could efficiently react with protein or DNA. In this in vitro model study, interaction between CDA and protein has been studied. Various proteins were incubated with CDA, and protein modification and adduct formation were confirmed by using matrix‐assisted laser desorption and ionization time‐of‐flight, amino acid analysis, and measuring enzyme activity on modification with CDA. Using radiolabeled NaB(3H)H4 and Raney nickel as well as sulfhydryl assay (Ellman's reagent), we confirmed that CDA could conjugate with cysteine through a thioether linkage. The carbonyl assay using 2,4‐dinitrophenylhydrazine revealed the possible involvement of Schiff's base reaction between CDA and lysine. The adducts formed between β‐apo‐8‐carotenal (BA8C) and N‐acetylcysteine and BA8C and N‐acetyllysine were confirmed by HPLC and ESI‐MS. Our results suggest that CDA could alter protein function by post‐translational interaction with cysteine and lysine by thioether linkage and by schiff's based bonds, respectively. Thus, the formation of CDA adducts with proteins could alter functional properties of proteins responsible for maintaining cell homeostasis and thereby cause cellular toxicity. In view of these observations, further studies are required to understand the delicate balance between beneficial and/or harmful effects of carotenoids as a dietary supplement to slow age‐related macular degeneration progression.
Heizen mit Orchideen. Projekt “Prograss” nutzt artenreiche Wiesen zur Energieerzeugung
Authors: Sieg Birgit
Published: April 2011

Artenreiche Wiesen gehören in Deutschland und Europa inzwischen zu den stark gefährdeten Lebensräumen. Ihre Erhaltung erfordert eine regelmäßige Mahd, die eine Verbuschung und damit den Rückgang der lichtliebenden Wiesenpflanzen verhindert. Die geerntete Biomasse war bislang jedoch aufgrund ihres geringen Energiegehalts weder für die moderne Landwirtschaft noch zur Energieerzeugung verwertbar. Durch ein neues Verfahren gewinnen Wissenschaftler der Universität Kassel nun aus dem Pflanzenmaterial artenreicher Wiesen einen Festbrennstoff, der zur Wärmegewinnung eingesetzt werden kann. Dabei vergärt der extrahierte Pflanzensaft zu Biogas, während die festen Pflanzenbestandteile zu Pellets gepresst werden. So wollen die Wissenschaftler zum Schutz von Natur und Klima beitragen sowie zusätzliches Einkommen für Landwirte generieren.
Rätselhafte Lebensgemeinschaft im Reich der Archaea. Die Feuerkugel und ihr Urzwerg
Authors: Huber Harald , Rachel Reinhard
Published: April 2011

Nanoarchaeum equitans und Ignicoccus hospitalis sind anaerobe hyperthermophile Mikroorganismen. Sie repräsentieren eine einzigartige, rein archaeelle Lebensgemeinschaft, in der N. equitans zwingend auf seinen Wirt I. hospitalis angewiesen ist, da es alle seine Lipide und Aminosäuren von ihm bezieht. I. hospitalis lebt von der Reduktion elementaren Schwefels mit Wasserstoff. Er besitzt einen neuen CO2‐Fixierungsweg und eine für Archaeen einmalige Zellstruktur aus innerer und äußerer Membran, die zwei Zellkompartimente bilden, das Cytoplasma und einen großen Intermembranraum. Durch immunologische Analysen zeigten wir, dass bei I. hospitalis die ATP‐Synthase‐ und die H2:Schwefel‐Oxidoreduktase‐Komplexe in seiner äußeren Membran lokalisiert sind. Damit ist er der erste Prokaryot mit einer energetisierten äußeren Membran, ATP‐Synthese außerhalb des Cytoplasmas und der räumlichen Trennung von Energiekonservierung und Informationsübertragung oder Proteinbiosynthese. Daraus ergeben sich zahlreiche Fragen zur Funktion und Charakterisierung der beiden Membranen und Zellkompartimente sowie einem möglichen Energietransfer zu N. equitans.
Vegetarismus. Mehr als ein Ernährungsstil
Authors: Leitzmann Claus
Published: April 2011

In den vergangenen Jahrzehnten hat sich die gesellschaftliche Stellung der Vegetarier deutlich verbessert. Wissenschaftliche Studien konnten überzeugend nachweisen, dass eine ausgewogene lakto‐ovo‐vegetarische Ernährung eine optimale Versorgung mit allen Nährstoffen für alle sichern kann. Vegetarier praktizieren ihre Ernährung vorwiegend aus ethischen Gründen, gesundheitlichen Anliegen und ökologischen Motiven. Der Vegetarismus trägt zur globalen Ernährungssicherung und zum nachhaltigen Umgang mit natürlichen Ressourcen bei. Die Umstellung auf eine vegetarische Ernährung erfordert Überzeugung und verlangt Kenntnisse für die richtige Auswahl und Zubereitung der Kost. Vegetarier berichten über ihre hohe Lebensqualität – nicht nur, weil sie länger leben.
Wolfgang von Buddenbrock, Wegbereiter der vergleichenden Physiologie
Authors: Bückmann Detlef
Published: April 2011

Lange vor seinem Erfolg als Buchautor war von Buddenbrock als erfolgreicher Forscher bekannt. Als besonders guter Beobachter entdeckte er neue Lebensformen und trug insbesondere dazu bei, die Sinnesleistungen ganz unterschiedlicher Organismen besser zu verstehen. Trotz seiner Erfolge blieb er bescheiden und setzte sich sehr für seine Studenten ein – die dankten es ihm, indem sie ihn liebevoll als “Opa” bezeichneten.
Der fleischfressende Wasserschlauch saugt seine Beute ein
Authors: Wendler Silke
Published: April 2011

Schon seit Darwins ersten Versuchen an fleischfressenden Pflanzen sind die Forscher von der einzigartigen Fangmethode des Wasserschlauchs fasziniert. Sein Beutefang zählt zu den schnellsten Bewegungen im Pflanzenreich. Bisher konnte der blitzartige Fangmechanismus aufgrund mangelnder bildgebender Verfahren nicht genauer analysiert werden. Forschern der Universitäten Grenoble und Freiburg ist es nun mit Hilfe einer neuartigen High‐Speed‐Kamera gelungen, das Geheimnis zu lüften.
Bluthirnschranke: Bis hierher und nicht weiter
Authors: Kronberg Inge
Published: April 2011

Das Gehirn des Menschen entspricht zwar nur etwa 2% seines Körpergewichtes, benötigt aber 20% der Energie. Es muss durch das Blut mit entsprechend viel Sauerstoff und Nährstoffen versorgt werden, aber vor Krankheitserregern, Giftstoffen sowie Hormonen geschützt werden und Stoffwechselendprodukte abgeben können. Zu diesem Zweck trennen spezialisierte Zellen die Milieubedingungen des Gehirns von denen des Blutes und kontrollieren den selektiven Stoffaustausch. Diese Bluthirnschranke ist entscheidend für die neuronalen Funktionen und verhindert Schädigungen des Zentralnervensystems. Welche Zellen dafür verantwortlich sind und wann sie in der Embryogenese gebildet werden, konnte jetzt an Versuchen mit Mäusen und Ratten näher eingegrenzt werden.
Ein Zufallsfund schließt Lücken in der Florengeschichte
Authors: Högermann Christiane
Published: April 2011

Es war der buchstäbliche Schatz auf dem Dachboden: Zufällig entdeckt wurde ein vollständiges “Herbarium vivum” mit circa 1500 Pflanzen aus 727 Arten, darunter auch einige in Leder gebundene Folianten, einschließlich eines ausführlichen Manuskripts aus der Zeit um 1830. Heute befassen sich Wissenschaftler mit der Pflanzensammlung – und entdecken darin viel Spannendes über die Vegetationsgeschichte von Nordwestdeutschland.
Hundert Jahre Wissenschaftsbegriff “Ethologie”: eine kritische Bilanz
Authors: Schurig Volker
Published: April 2011

Das hundertjährige Bestehen des Begriffs “Ethologie” in der Biologie liefert ein Beispiel für die unentbehrliche Funktion hochrangiger biologischer Wissenschaftsbegriffe und die fatalen Folgen bei ihrem Ausfall für den Status des damit bezeichneten Wissenschaftssystems.
Explicit and implicit animation with fuzzy constraints of a versatile multi‐body system for virtual hand surgery
Authors: Gourret Jean‐Paul , Hariri Amir , Liverneaux Philippe
Published: April 2011

This work is designed to control the movement of hand structural agents under external action, using the implicit animation driven by explicit animation technique (AI‐CAE technique). Starting from the configuration of a hand at rest obtained by a 3D scanner and after meshing of the structural agents, we seek the configuration of the rigid agents under orthopaedic surgeon external action and interacting reliance of deformable and rigid agents. We have developed a model and software tools to answer this interactive application with adaptive execution. The first contribution comes from notations and definition of a versatile multi‐body system dedicated to the explicit and implicit animation. The second contribution comes from the implicit animation driven by explicit animation itself, and from its ability to mimic the role of cartilages and ligaments. The resulting technique is applied to the bone structure consistency of a specific human hand in the context of virtual hand orthopaedic surgery. The versatile specific multi‐body is made up of hierarchical interacting agents conceivable as a construction set of rigid bones with cartilages–ligaments and underlying links. The explicit animation produces a desired configuration from geometric command parameters of torsion, flexion, pivot and axis shifting, given in a scenario subdivided into temporal sequences. The implicit animation controls the movement by implementing a physics‐based model and fuzzy constraints of position and orientation. It gives better configuration than the explicit animation because it takes into account the interactions between agents, and it gives a neat solution without the problems of complexity due to geometric modelling. A methodology based on the AI‐CAE technique is discussed, medical expertise and validation tests are presented. Copyright © 2011 John Wiley & Sons, Ltd.