bluuebunny/crossref_metadata_2025_split huggingface dataset:
Detection of Biomechanical Changes After Corneal Cross-Linking Using Ocular Response Analyzer Software
Authors: Spoerl Eberhard , Terai Naim , Scholz Freia , Raiskup Frederik , Pillunat Lutz E. 
Published: January 2011

Purpose:
To investigate biomechanical changes after corneal cross-linking (CXL) with riboflavin/ultraviolet-A (UVA) in keratoconus using the recently developed Ocular Response Analyzer (ORA, Reichert Technologies) software.

Methods:
Through use of the new ORA software (version 2.04), 37 new parameters derived from the best measurement signal with the highest wavescore of 4 measurements from 50 eyes of 46 patients with keratoconus were obtained before and 1 year after CXL. The parameters of 96 eyes from 96 age-matched, healthy individuals with a spherical equivalent refraction <3.00 diopters served as controls.

Results:

Corneal hysteresis (CH) and corneal resistance factor (CRF) before CXL were 7.38±1.42 mmHg and 6.16±1.42 mmHg, respectively, compared to 7.37±1.26 mmHg (
P
=.971) and 6.16±1.50 mmHg after CXL (
P
=.997), respectively. Based on these 37 new parameters, the area under peak 2 (p2area) showed a statistically significant increase from 1262.3±623.1 before CXL to 1704.3±732.3 1 year after CXL (35%;
P
=.001). The related value for the p2area of the healthy control group was 3374.9±1099.9. A significant negative correlation was observed between the p2area and the difference in CH-CRF values (r=−0.29,
P
=.001).

Conclusions:
The area under peak 2 appears to be a more sensitive parameter to detect biomechanical changes after CXL than CH or CRF alone. After CXL, keratoconic corneas display altered biomechanical properties, which remain different to those observed in healthy corneas.
Bioptics in Sutureless Intrascleral Multifocal Posterior Chamber Intraocular Lens Fixation
Authors: Pavlidis Mitrofanis , de Ortueta Diego , Scharioth Gabor B. 
Published: January 2011

Purpose:
To present a technique for sutureless fixation of a three-piece, multifocal, posterior chamber intraocular lens (IOL) in the ciliary sulcus.

Methods:
A 24-year-old woman presented with bilateral subluxation of the crystalline lens. Two straight sclerotomies were prepared with a 24-gauge cannula 2.0 mm from the limbus 180° apart from each other. The cannula was used to create a 2.0- to 3.0-mm tunnel parallel to the limbus starting from the sclerotomies. The leading haptic of the multifocal IOL was grasped at its tip with end-gripping, 25-gauge forceps and pulled through the sclerotomy. The forceps was used to introduce the IOL haptic into the scleral tunnel parallel to the limbus.

Results:
Multifocal posterior chamber IOLs were stable and well centered. No postoperative complications occurred in the 16-month follow-up period. Preoperative astigmatism was corrected after IOL implantation with corneal wavefront-guided laser epithelial keratomileusis.

Conclusions:
Sutureless fixation of multifocal posterior chamber IOL haptics in a scleral tunnel parallel to the limbus can be successful, resulting in long-term centration and three-dimensional axial stability for optimal refractive results. If necessary, postoperative wavefront-guided refractive correction can be performed to optimize final refraction.
Hydrogen Production from Renewables
Authors: Navarro Rufino M. , Sanchez‐Sanchez M. Cruz , Alvarez‐Galvan M. Consuelo , Fierro Jose Luis G. , Al‐Zaharani Saeed M. 
Published: January 2011

AbstractHydrogen is considered to be critical for energy and environmental sustainability. However, as hydrogen is currently produced from fossil fuels, it emits large amounts of carbon dioxide along the reforming steps. The technical challenges to achieve a stable hydrogen economy include improving process efficiencies, lowering the cost of production, and harnessing renewable sources for hydrogen production. Lignocellulosic biomass is one of the most abundant forms of renewable resources. When this precursor is used, virtually no net greenhouse gas emissions result because a natural cycle is maintained, in which carbon is extracted from the atmosphere during plant growth and is released during hydrogen production. This article focuses on recent developments in biomass and biomass‐derived product conversion to H2. The second option explored here is the conversion of solar energy into hydrogen via water‐splitting processes assisted by two‐step metal‐oxide thermochemical cycles or by photosemiconductor catalysts. The conversion of solar energy into a clean fuel (H2) is the most promising technology for the future because large quantities of hydrogen can potentially be generated in a clean and sustainable manner. Undoubtedly, the conversion of solar energy into H2is one of the greatest challenges scientists are facing in the twenty first century. A survey is presented of the advances made in the development of metal oxide redox pairs since the pioneering work by Nakamura in 1977 and in the development of photocatalysts for water splitting under visible light since the first work of Fujishima and Honda in 1972. The very high thermal reduction temperature used for the metal oxide redox pairs developed until now leads to severe sintering, melting, and vaporization of materials, decreasing the efficiency and durability in the cyclic operation. Consequently, the application of material science and engineering to the development of materials with lower reduction temperature and high water‐splitting ability is still a challenge in this scientific area and an overview of the progress is provided in this article. On the other hand, there are still major challenges in the development of photocatalysts with improved efficiencies for hydrogen production from water using solar energy. An overview is provided in this article of research strategies and approaches adopted in the search for photocatalysts for water splitting under visible light (new photocatalyst materials and the control of the synthesis of materials for customizing the crystallinity, electronic structure, and morphology of catalysts at nanometric scale).
Fuel Cells: Enzymes and Microbes for Energy Production
Authors: Barrière Frédéric 
Published: January 2011

Abstract
The use of redox enzymes and bacteria as catalysts at the electrodes of fuel cells is reviewed with an emphasis on some inorganic aspects of the research. In biofuel cells, redox enzymes catalyze the oxidation of organic substrates like glucose at the anode or the reduction of electron acceptors like dioxygen at the cathode. Many of the redox enzymes have metal‐active sites that are of interest to the bioinorganic chemist. Moreover, efficient electrical linking between a redox enzyme and an electrode requires the mediation of a small electroactive molecule, capable of diffusing and shuttling electrons between the core of the enzyme and the electrode surface. These redox mediators may be coordination or organometallic complexes. In microbial fuel cells, the biocatalysts are living microorganisms, most often bacteria. At the anode, the bacteria metabolize organic substrates like sugars or acetate. In the absence of dioxygen or other natural electron acceptors, some species of bacteria may transfer electrons to the anode of a fuel cell. Different mechanisms for bacterial anodic electron transfer are proposed and discussed in this article. One common feature of these processes is the direct or indirect linking of the electrode surface to the outer‐membrane‐bound electron‐transfer chain of the respiratory system of bacteria. This system contains a chain of redox enzymes containing cytochrome‐type active sites that may be directly electrochemically addressed in some cases. At the cathode of microbial fuel cell, some bacteria may also accept electrons and catalyze the reduction of electron acceptors like nitrate, sulfate, and dioxygen. Given the importance of dioxygen reduction in most fuel cells, a perspective is given on the way inorganic chemistry may contribute to the design of efficient electrode catalysts through molecular, material, enzymatic, or biological approaches. Finally, the prospect of self‐sustained biological fuel cell is discussed with integration of plants with their anolyte as an in situ fuel provider in the form of root exudates, or enrichment of dioxygen in their catholyte with photosynthetic activity of algae. Although the emphasis is on the inorganic themes of biological fuel cell research, the important multidisciplinary approaches of the topic are put forward. This article also contains discussions on the relative performances and applications of both types of biological fuel cells.
Fuel Cells: Proton Exchange Membranes
Authors: Devanathan Ram 
Published: January 2011

Abstract

Proton exchange membrane, also known as polymer electrolyte membrane, fuel cells (PEMFCs) offer the promise of efficient conversion of chemical energy of fuel, such as hydrogen or methanol, into electricity with minimal pollution. Their widespread use to power zero‐emission automobiles as part of a hydrogen economy can contribute to enhanced energy security and reduction in greenhouse gas emissions. However, the commercial viability of PEMFC technology is hindered by high cost associated with the membrane‐electrode assembly (MEA) and poor membrane durability under prolonged operation at elevated temperature. Membranes for automotive fuel cell applications need to perform well over a period comparable to the life of an automotive engine and under heavy load cycling including start‐stop cycling under subfreezing conditions. The combination of elevated temperature, changes in humidity levels, physical stresses, and harsh chemical environment contribute to membrane degradation. Perfluorinated sulfonic acid (PFSA)‐based membranes, such as Nafion
®
, have been the mainstay of PEMFC technology. Their limitations, in terms of cost and poor conductivity at low hydration, have led to continuing research into membranes that have good proton conductivity at elevated temperatures above 120 °C and under low‐humidity conditions. Such membranes have the potential to avoid catalyst poisoning, simplify fuel cell design, and reduce the cost of fuel cells. Hydrocarbon‐based membranes are being developed as alternatives to PFSA membranes, but concerns about chemical and mechanical stability and durability remain. Novel anhydrous membranes based on polymer gels infused with protic ionic liquids have also been recently proposed, but considerable fundamental research is needed to understand proton transport in novel membranes and evaluate durability under fuel cell operating conditions. In order to advance this promising technology, it is essential to rationally design the next generation of PEMs on the basis of an understanding of chemistry, membrane morphology, and proton transport obtained from experiment, theory, and computer simulation.
Oxygen Production from Water: Molecular Catalysts
Authors: Llobet Antoni , Romain Sophie 
Published: January 2011

Abstract
This article presents an overview of the established basis needed for the oxidation of water to dioxygen, and thus the demands a catalyst needs to fulfill to be able to perform this reaction. It further describes the structure, redox properties, and performance of selected molecular catalysts that have been reported to be able to perform this difficult reaction and that can be considered as references in the field. The scarce reaction mechanism studies that have been described are also summarized and discussed. The article mainly deals with Ru complexes, because they constitute most of the available literature at the moment, and are classified as a function of their nuclearity. Other transition metal complexes of relevance based on Ir, Co, and Mn are also described. Finally, a few conclusions are drawn from the global description of all of the catalysts presented here, and the challenges and opportunities in the field are also discussed.
Photosynthesis: Energy Conversion
Authors: Ulas Gözde , Brudvig Gary W. 
Published: January 2011

AbstractThe process of water oxidation and carbon dioxide reduction in oxygenic photosynthesis involves a complex series of events that start with light energy capture and end with its storage in the form of the chemical energy in glucose. These reactions provide a solution to efficient solar energy conversion into high‐energy chemicals. The principles revealed by study of natural photosynthetic systems may be used to design artificial systems for solar fuel production. Understanding the light‐driven oxidation of water, in particular, is of high interest, as this half reaction could be used in sustainable solar fuel production by processes of artificial photosynthesis to meet the world's growing energy demand. In this article, we look into the intricate photosynthetic machinery and the various processes that it performs in order to efficiently capture, convert, and store light energy. Our main focus is on the so‐called “light” reactions, where specific processes are driven by direct light absorption. As a result, reducing equivalents are extracted from water and transferred to NADP+, to be used in the carbon‐fixing reactions, which are not directly modulated by sunlight. We describe the characteristic features of each protein in the photosynthetic electron‐transport machinery, and specifically focus on the water‐oxidation catalysis performed as the first step of oxygenic photosynthesis by the metalloenzyme photosystem II, due to its relevance to synthetic biomimetic water‐oxidation catalysts. Several processes that photosystem II employs to couple light energy absorption to catalytic turnover are discussed, including proton and electron transfers, redox leveling, charge accumulation, and proposed catalytic mechanisms.
Fuel Cells: Intermediate Temperature Solid Oxides
Authors: Atkinson Alan , Kilner John , Skinner Stephen , Brandon Nigel P. , Brett Dan J. L. 
Published: January 2011

Abstract
Fuel cells are electrochemical energy conversion devices that convert chemical energy in fuels directly into electrical energy, without the process of combustion. As a result, they are not constrained by the same thermodynamic limitations as those of heat engines and therefore have the potential to achieve higher efficiencies. High‐temperature solid oxide fuel cells (HT‐SOFCs) operate up to 1000 °C. These fuel cells achieve very high system efficiencies when integrated with gas turbines for large‐scale stationary applications. However, operation at such high temperatures means that the components of the stack need to be predominantly ceramic, in addition to expensive high‐temperature metal alloys. For smaller scale applications, there is a trend to move to lower operating temperatures, into the so‐called intermediate‐temperature (IT) range of 500–750 °C. In doing so, a wider range of construction materials can be used, offering reduced system cost and, in principle, improved performance durability. In this article, we introduce the IT‐SOFC and explain their main operational advantages. We also focus on the combination of inorganic materials and processing routes that go to make reduced temperature SOFC operation possible.
Energy Research: Computational Challenges
Authors: Batista Victor S. 
Published: January 2011

AbstractThe emergence of photocatalytic solar cells based on semiconductor materials functionalized with earth‐abundant transition metal complexes represent a promising development for the sustainable production of fuel from renewable resources (e.g., water). This article reviews recent advances in studies of nanoporous TiO2 thin films sensitized with manganese catalysts, with emphasis on recent computational work integrated with synthesis, electrochemistry, and spectroscopy. The resulting interdisciplinary approach addresses fundamental aspects that affect the overall efficiency of photocatalytic mechanisms, including proton‐coupled electron transfer, rectification of interfacial electron transfer, and visible light absorption, providing guidelines for the design of novel photocatalytic materials for fuel production.
Supercapacitors: Electrode Materials Aspects
Authors: Zhang Li Li , Lei Zhibin , Zhang Jintao , Tian Xiaoning , Zhao Xiu Song 
Published: January 2011

AbstractGlobal warming and the finite nature of fossil fuels have driven the world to adopt sustainable and renewable energies. Electrochemical energy conversion and storage systems are considered as such energy sources. As a bridge between high‐power‐output conventional capacitors and high‐energy‐density batteries, supercapacitors (also known as ultracapacitors or electrical double layer capacitors) are an ideal electrochemical energy‐storage system, suitable for rapid storage and release of energy. In comparison with that of batteries, the energy density of supercapacitors is much lower. Therefore, improving the energy density without sacrificing the high power density of supercapacitors has been a key research direction in developing high‐performance supercapacitor devices. The properties of the active electrode materials, including surface area, pore size, pore connectivity, electric conductivity, and surface chemistry, play a crucial role in determining the ultimate performance of the supercapacitor. This article presents an overview of literature data on supercapacitor electrode materials. With a brief description of the structure and energy‐storage mechanism of supercapacitors, recent advancements in electrode materials including carbon‐based materials (e.g., activated carbon, templated carbon, carbon nanotubes, graphene), transition‐metal oxides, and conducting polymers are summarized and discussed.
Anisotropy of Charge Transport in a Uniaxially Aligned and Chain‐Extended, High‐Mobility, Conjugated Polymer Semiconductor
Authors: Lee Mi Jung , Gupta Dhritiman , Zhao Ni , Heeney Martin , McCulloch Iain , Sirringhaus Henning 
Published: January 2011

AbstractCharge transport in the ribbon phase of poly(2,5‐bis(3‐alkylthiophen‐2‐yl)thieno[3,2‐b]thiophene) (PBTTT)—one of the most highly ordered, chain‐extended crystalline microstructures available in a conjugated polymer semiconductor—is studied. Ribbon‐phase PBTTT has previously been found not to exhibit high carrier mobilities, but it is shown here that field‐effect mobilities depend strongly on the device architecture and active interface. When devices are constructed such that the ribbon‐phase films are in contact with either a polymer gate dielectric or an SiO2 gate dielectric modified by a hydrophobic, self‐assembled monolayer, high mobilities of up to 0.4 cm2 V−1 s−1 can be achieved, which is comparable to those observed previously in terrace‐phase PBTTT. In uniaxially aligned, zone‐cast films of ribbon‐phase PBTTT the mobility anisotropy is measured for transport both parallel and perpendicular to the polymer chain direction. The mobility anisotropy is relatively small, with the mobility along the polymer chain direction being higher by a factor of 3–5, consistent with the grain size encountered in the two transport directions.
Equilibrium and kinetics of vancomycin adsorption on polymeric adsorbent
Authors: Likozar Blaž , Senica David , Pavko Aleksander 
Published: January 2011

AbstractIsolation step of vancomycin, a glycopeptide antibiotic, is usually done from fermentation broth filtrate, while its adsorption directly from the whole broth could rationalize the process. The equilibrium and kinetics of vancomycin adsorption from broth supernatant, diluted and whole broth on polymeric adsorbent was studied in this work. Experimental equilibrium data was correlated with Sips, Langmuir, Freundlich, and linear adsorption isotherms. Agreement between measured and regressed data for the first three mentioned models did not vary much and was relatively high. The maximum adsorbed amount for supernatant was higher than for fermentation broths because mycelium particles blocked adsorbent surface. Liquid film mass transfer studies showed that external mass transfer resistance could have been neglected. Diffusion of vancomycin inside adsorbent particles was acknowledged using a nonstructural, homogenous surface diffusion and bidisperse pore models. Model simulations indicated that kinetics of the process could be improved by using smaller adsorbent particles. © 2011 American Institute of Chemical Engineers AIChE J, 2012
Power‐law polymer solution flow in a converging annular spinneret: Analytical approximation and numerical computation
Authors: Tung Kuo‐Lun , Li Yu‐Ling , Hu Che‐Chia , Chen Yu‐Shao 
Published: January 2011

AbstractA simplified analytical solution for the flow of power‐law liquids through a conical annulus was derived to estimate the flow profile, wall shear rate, and elongation rate in the spinneret during the spinning of hollow fiber membranes. The velocity profiles and shear and elongation rates of the power‐law fluid showed good agreement with those obtained from computational fluid dynamic simulations. Although the actual spinneret is characterized by an annulus with a converging cross section, most studies to date have used a geometrical concentric annulus for the sake of simplicity. The results of the current work indicate that neglecting the converging characteristics of the actual spinneret can lead to significant underestimation of the wall shear rate. Using the equations derived in our work, we were able to predict not only the velocity profile but also the wall shear rate and the elongation rate; the influence of the spinneret design on the membrane morphology and properties were also examined. © 2011 American Institute of Chemical Engineers AIChE J, 2012
The dining etiquette of desert baboons: the roles of social bonds, kinship, and dominance in co‐feeding networks
Authors: King Andrew J. , Clark Fay E. , Cowlishaw Guy 
Published: January 2011

AbstractTo better understand how individual relationships influence patterns of social foraging in primate groups, we explored networks of co‐feeding in wild desert baboons (Papio ursinus). To minimize the risk of aggression and injury associated with contest competition, we expected that individual group members would choose to co‐feed with those group‐mates that are most likely to show tolerance and a willingness to share food patches. We tested two alternative hypotheses about who those group‐mates might be: the “social bonds hypothesis” predicts that preferred foraging partners will be those with whom individuals share strong social bonds, indexed by grooming, whereas the “kinship hypothesis” predicts that preferred foraging partners will be relatives. We also investigated and controlled for the effects of dominance rank, given that competitive ability is known to shape foraging patterns. Social network analyses of over 5,000 foraging events for 14 adults in a single troop revealed that baboon co‐feeding was significantly correlated with grooming relationships but not genetic relatedness, and this finding was also true of the female‐only co‐feeding network. Dominant individuals were also found to be central to the co‐feeding network, frequently sharing food patches with multiple group‐mates. This polyadic analysis of foraging associations between individuals underlines the importance of dominance and affiliation to patterns of primate social foraging. Am. J. Primatol. 73:768–774, 2011. © 2011 Wiley‐Liss, Inc.