bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biodegradable Thermogelling Poly(D,L‐lactide‐co‐p‐dioxanone)‐Poly(ethylene glycol)‐Poly(D,L‐lactide‐co‐p‐dioxanone) Triblock Copolymer
Authors: Chen Rui , Hao Jianyuan , Xiong Chengdong , Deng Xianmo 
Published: September 2010

AbstractThermogelling poly(D,L‐lactide‐co‐p‐dioxanone)–poly(ethylene glycol)–poly (D,L‐ lactide‐co‐p‐dioxanone) [P(LA‐PDO)–PEG–P(LA‐PDO)] triblock copolymers were successfully prepared by ring‐opening copolymerization of D,L‐lactide and p‐dioxanone in the presence of PEG as a macromolecular initiator and stannous octoate as a catalyst. The aqueous solutions of the copolymers underwent clear double sol–gel and then gel–sol transitions with increasing temperature from 0 to 50 °C. It was found that the lower critical solution transition (LCST) temperature could be effectively controlled by adjusting the molar ratio of LA/PDO or PEG length in the copolymers. The introduction of PDO units into the hydrophobic block has greatly accelerated the water dissolution rate of the copolymers and facilitated the drug formulation. The developed thermosensitive hydrogel has suitable sol–gel transition temperature and is a promising injectable material for drug delivery depot and tissue engineering scaffold.
Biomimetic Composites: Protein Localization in Silica Nanospheres Derived via Biomimetic Mineralization (Adv. Funct. Mater. 18/2010)
Authors: Cardoso Mateus B. , Luckarift Heather R. , Urban Volker S. , O'Neill Hugh , Johnson Glenn R. 
Published: September 2010

AbstractLysozyme‐templated precipitation of silica synthesized by sol‐gel chemistry produces a composite material with antimicrobial properties. This study investigates the structural properties of the composite material that allow for retention of the antimicrobial activity of lysozyme. Scanning (SEM) and transmission (TEM) electron microscopy reveal that the composite has a hierarchical structure composed of quasi‐spherical structures (∼450 nm diameter), which are in turn composed of closely packed spherical structures of ∼8–10 nm in diameter. Using small‐angle neutron scattering (SANS) with contrast variation, the scattering signatures of the lysozyme and silica within the composite were separated. It was determined that the lysozyme molecules are spatially correlated in the material and form clusters with colloidal silica particles. The size of the clusters determined by SANS agrees well with the structural architecture observed by TEM. BET analysis revealed that the surface area of the composite is relatively low (4.73 m2/g). However, after removal of the protein by heating to 200 °C, the surface area is increased by ∼20%. In addition to demonstrating a well organized sol‐gel synthesis which generates a functional material with antimicrobial applications, the analysis and modeling approaches described herein can be used for characterizing a wide range of mesoporous and ultrastructural materials.
Hydrothermal Growth: Polymer‐Templated Hydrothermal Growth of Vertically Aligned Single‐Crystal ZnO Nanorods and Morphological Transformations Using Structural Polarity (Adv. Funct. Mater. 18/2010)
Authors: Kim Ki Seok , Jeong Hyun , Jeong Mun Seok , Jung Gun Young 
Published: September 2010

AbstractPosition‐configurable, vertical, single‐crystalline ZnO nanorod arrays are fabricated via a polymer‐templated hydrothermal growth method at a low temperature of 93 °C. A sol‐gel processed dense c‐oriented ZnO seed layer film is employed to grow nanorods along the c‐axis direction [0001] regardless of any substrate crystal mismatches. Here, one‐beam laser‐interference lithography is utilized to fabricate nanoscale holes over an entire 2‐in. wafer during the preparation of the polymer template. As such, vertically aligned ZnO nanorods can be grown from the seed layer exposed at the bottom of each hole. Furthermore, morphological transformations of the ZnO nanorods into pencil‐like, needle‐like, tubular, tree‐like, and spherical shapes are obtained by controlling the growth conditions and utilizing the structural polarity of the ZnO nanorods.
Immobilization of a Modified Tethered Rhodium(III)‐p‐Toluenesulfonyl‐1,2‐diphenylethylenediamine Catalyst on Soluble and Solid Polymeric Supports and Successful Application to Asymmetric Transfer Hydrogenation of Ketones
Authors: Dimroth Jonas , Keilitz Juliane , Schedler Uwe , Schomäcker Reinhard , Haag Rainer 
Published: September 2010

AbstractCatalyst immobilization through covalent attachment onto a support is one strategy to provide recyclable systems. Here, soluble and surface‐functionalized solid polymers were used as supports for a modified tethered rhodium(III)‐p‐toluenesulfonyl‐1,2‐diphenylethylenediamine [Rh(III)‐TsDPEN] complex. The supported catalysts were applied to the asymmetric transfer hydrogenation of phenyl ketones in aqueous solution of sodium formate. High ee values (up to 99%) and good activities were achieved. It was discovered that the solid polymer‐supported catalyst could be recycled at least four times without a significant decrease of the activity when a mixture of sodium formate and formic acid was used as the hydrogen source. This catalytic system provides a promising approach towards an ecologically and economically rational production of enantioenriched building blocks.
Multi‐objective state feedback control for linear delay systems
Authors: Xie Wei , Eisaka Toshio 
Published: September 2010

AbstractThis paper provides new linear matrix inequalities (LMI)‐based formulae for mixed H2/H∞state‐feedback synthesis of linear continuous‐time systems with state delays of any size. The proposed delay‐independent LMI‐based conditions enable us to parameterize a memoryless state‐feedback controller without involving the Lyapunov variables in the formula. Compared with previous results based on a common Lyapunov variable, the proposed formula provides less conservative results.Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Communicating bioenergy: a growing challenge
Authors: McCormick Kes 
Published: September 2010

AbstractBioenergy is rapidly growing in many parts of the world. But continued investments in bioenergy do not depend entirely on technological advances, feedstock availability, and economic conditions. The social acceptance of bioenergy by the general public appears to be essential to the political legitimacy of the bioenergy industry, and the willingness of policy‐makers to introduce or maintain supportive policy schemes for bioenergy. In the context of Europe, this perspective argues that communication strategies will become increasingly important for the bioenergy industry as it continues to expand. In short, this perspective discusses four main questions, including: What is the current social acceptance of bioenergy among citizens in Europe? What are the key lessons from experiences with communication on bioenergy? What are the emerging ‘hot’ topics for the bioenergy industry? What international efforts are underway to inform the general public about bioenergy? Overall, this perspective aims to provide insights into the linkages between the social acceptance and the political legitimacy of bioenergy, and the role of communication strategies. © 2010 Society of Chemical Industry and John Wiley & Sons, Ltd
Bringing the excitement and motivation of research to students; Using inquiry and research‐based learning in a year‐long biochemistry laboratory
Authors: Knutson Kristopher , Smith Jennifer , Wallert Mark A. , Provost Joseph J. 
Published: September 2010

AbstractA successful laboratory experience provides the foundation for student success, creating active participation in the learning process. Here, we describe a new approach that emphasizes research, inquiry and problem solving in a year‐long biochemistry experience. The first semester centers on the purification, characterization, and analysis of a novel fusion protein within a guided research experience. Throughout the semester, students gradually acquire skills as they are allowed to work independently. A fusion protein, malate dehydrogenase‐green fluorescent protein with a histidine affinity tag (MGH), is used throughout the semester. The fusion protein allows for a high throughput analysis and is stable for duration of the semester. Students start with the purification and analysis of the plasmid DNA and end with an enzymatic analysis of MGH. As students take ownership of their experiments and choose two different chromatographic resins, they make many choices throughout the semester. Skills, motivation, confidence levels, and attitudes were assessed before and after the semester. Students achieved high levels of critical biochemical laboratory skills and critical thinking while increasing their confidence and motivation for working in a biochemical research setting.
Bringing the excitement and motivation of research to students; Using inquiry and research‐based learning in a year‐long biochemistry laboratory
Authors: Knutson Kristopher , Smith Jennifer , Nichols Paul , Wallert Mark A. , Provost Joseph J. 
Published: September 2010

AbstractResearch‐based learning in a teaching environment is an effective way to help bring the excitement and experience of independent bench research to a large number of students. The program described here is the second of a two‐semester biochemistry laboratory series. Here, students are empowered to design, execute and analyze their own experiments for the entire semester. This style of laboratory replaces a variety of shorter labs in favor of an in depth research‐based learning experience. The concept is to allow students to function in independent research groups. The research projects are focused on a series of wild‐type and mutant clones of malate dehydrogenase. A common research theme for the laboratory helps instructors administer the course and is key to delivering a research opportunity to a large number of students. The outcome of this research‐based learning laboratory results in students who are much more confident and skilled in critical areas in biochemistry and molecular biology. Students with research experience have significantly higher confidence and motivation than those students without a previous research experience. We have also found that all students performed better in advanced courses and in the workplace.
Evaluation of software for introducing protein structure
Authors: White Brian , Kahriman Azmin , Luberice Lois , Idleh Farhia 
Published: September 2010

AbstractCommunicating an understanding of the forces and factors that determine a protein's structure is an important goal of many biology and biochemistry courses at a variety of levels. Many educators use computer software that allows visualization of these complex molecules for this purpose. Although visualization is in wide use and has been associated with student learning, it is quite challenging to develop visualizations that allow students to interactively observe the effects of altered amino acid sequence on protein structure. A software simulation, the protein investigator (PI), has been developed to specifically facilitate this type of exploration. When using the PI, students enter or edit an amino acid sequence; the software then simulates its folding in two dimensions using the major forces involved in protein structure. This study explores freshman undergraduate students' use of visualization and simulation when learning about protein structure. It also evaluates some of the learning outcomes from these two approaches. Our results show that simulation leads to similar learning outcomes as visualization. Because simulation allows a more interactive exploration, a combination of the two approaches may be an effective approach to introducing the basic principles of protein structure.
Calibrated peer review for computer‐assisted learning of biological research competencies
Authors: Clase Kari L. , Gundlach Ellen , Pelaez Nancy J. 
Published: September 2010

AbstractRecently, both science and technology faculty have been recognizing biological research competencies that are valued but rarely assessed. Some of these valued learning outcomes include scientific methods and thinking, critical assessment of primary papers, quantitative reasoning, communication, and putting biological research into a historical and broader social context. This article presents examples of Calibrated Peer Review (CPR) assignments that illustrate a computer‐assisted method to help students achieve biological research competencies. A new release of CPR is appropriate for engaging students online in reading and writing about investigations. A participant perception inventory was designed for use as a repeated measure to discriminate among beginning, middle, and ending student perceptions. Examples are provided to demonstrate how to assess student perceptions of what they gain from instruction related to science research competencies. Results suggest that students in a large enrollment class consider CPR to be useful for helping them learn about quantitative and categorical research variables; the use of the experimental method to test ideas; the use of controls; analysis, interpretation, and presentation of data; and how to critically read primary papers.
Quantification of nicotine in commercial brand cigarettes
Authors: Vieira Carlos A. , de Paiva Sabina A. A. , Funai Milena N. S. , Bergamaschi Mateus M. , Queiroz Regina H. C. , Giglio José R. 
Published: September 2010

AbstractThe main objective of this experiment is to determine the amount of nicotine in commercial brand cigarettes by means of a nonaqueous acid‐base titration. A simple glass device simulating a smoker is proposed, which allows the determination of the volatilized, filter retained, and inhaled portions. Students will readily see that the amount of nicotine/cigarette stated on the label (∼0.5–1.0 mg) refers indeed to the inhaled portion only, rather than to the total amount/cigarette (usually more than 10 mg). Even so, values for inhaled nicotine may be significantly higher than those reported for several brands. Students will also be able to make a critical evaluation of the true content of nicotine in the inhaled portion and confront it with the reported value for a given brand. In addition, the theoretical approach, supported by HPLC data, provides an excellent experience on nonaqueous acid‐base volumetric analysis.
Bridging the educational research‐teaching practice gap
Authors: Schönborn Konrad J. , Anderson Trevor R. 
Published: September 2010

AbstractExternal representations (ERs), such as diagrams, animations, and dynamic models are vital tools for communicating and constructing knowledge in biochemistry. To build a meaningful understanding of structure, function, and process, it is essential that students become visually literate by mastering key cognitive skills that are essential for interpreting and visualizing ERs. In this article, first we describe a model of seven factors influencing students' ability to learn from ERs. Second, we use this model and relevant literature to identify eight cognitive skills central to visual literacy in biochemistry. Third, we present simple examples of tasks as a foundation for designing more sophisticated and complex items for assessing and developing students' visual literacy. We conclude that visual literacy is fundamental to the development of sound conceptual understanding and it is crucial to develop visual skills in parallel with meaningful learning outcomes in all biochemistry curricula.
Development and validation of an HPLC method for quantitation of BA‐TPQ, a novel iminoquinone anticancer agent, and an initial pharmacokinetic study in mice
Authors: Li Haibo , Ezell Scharri J. , Zhang Xiangrong , Wang Wei , Xu Hongxia , Rayburn Elizabeth R. , Zhang Xu , Gurpinar Evrim , Yang Xinyi , Sommers Charnell I. , Velu Sadanandan E. , Zhang Ruiwen 
Published: September 2010

AbstractWe herein describe the development and validation of an HPLC method for the quantitation of 7‐(benzylamino)‐1,3,4,8‐tetrahydropyrrolo [4,3,2‐de]quinolin‐8(1H)‐one (BA‐TPQ), a newly synthesized iminoquinone anticancer agent. BA‐TPQ was extracted from plasma and tissue samples by first precipitating proteins with acetonitrile followed by a liquid–liquid extraction with ethyl acetate. Chromatographic separation was carried out using a gradient flow rate on a Zorbax SB C18 column, and the effluent was monitored by UV detection at 346 nm. The method was found to be precise, accurate, and specific, with a linear range of 3.91–1955.0 ng/mL in plasma, 19.55–1955.0 ng/mL in spleen, brain, and liver homogenates and 19.55–3910.0 ng/mL in heart, lung and kidney homogenates. The method was stable under all relevant conditions. Using this method, we also carried out an initial study determining plasma pharmacokinetics and tissue distribution of BA‐TPQ in mice following intravenous administration. In summary, this simple and sensitive HPLC method can be used in future preclinical and clinical studies of BA‐TPQ.
Antibacterials from the Sea
Authors: Hughes Chambers C. , Fenical William 
Published: September 2010

AbstractThe ocean contains a host of macroscopic life in a great microbial soup. Unlike the terrestrial environment, an aqueous environment provides perpetual propinquity and blurs spatial distinctions. Marine organisms are under a persistent threat of infection by resident pathogenic microbes including bacteria, and in response they have engineered complex organic compounds with antibacterial activity from a diverse set of biological precursors. The diluting effect of the ocean drives the construction of potent molecules that are stable to harsh salty conditions. Members of each class of metabolite—ribosomal and non‐ribosomal peptides, alkaloids, polyketides, and terpenes—have been shown to exhibit antibacterial activity. The sophistication and diversity of these metabolites points to the ingenuity and flexibility of biosynthetic processes in Nature. Compared with their terrestrial counterparts, antibacterial marine natural products have received much less attention. Thus, a concerted effort to discover new antibacterials from marine sources has the potential to contribute significantly to the treatment of the ever increasing drug‐resistant infectious diseases.
A Useful, Reliable and Safer Protocol for Hydrogenation and the Hydrogenolysis ofO‐Benzyl Groups: The In Situ Preparation of an Active Pd0/C Catalyst with Well‐Defined Properties
Authors: Felpin François‐Xavier , Fouquet Eric 
Published: September 2010

AbstractA simple, highly reproducible protocol for the hydrogenation of alkenes and alkynes and for the hydrogenolysis ofO‐benzyl ethers has been developed. The method features the in situ preparation of an active Pd0/C catalyst from Pd(OAc)2and charcoal, in methanol. The mild reaction conditions (25 °C) and low catalyst loading required (0.025 mol %), as well as the absence of contamination of the product by palladium residues (<4 ppb), make this a sustainable, useful process for organic chemists. Alternatively, the protocol can be carried out under microwave activation, to shorten the reaction times, with cyclohexene as the hydrogen source.
Stereodynamics of tetramezine
Authors: Kamuf Matthias , Trapp Oliver 
Published: September 2010

AbstractThe antidepressant drug tetramezine [1,2‐bis‐(3,3‐dimethyldiaziridin‐1‐yl)ethane] consists of two bridged diaziridine moieties with four stereogenic nitrogen centers, which are stereolabile and, therefore, are prone to interconversion. The adjacent substituents at the nitrogen atoms of the diaziridines moieties exist only in an antiperiplanar conformation, which results in a coupled interconversion. Therefore, three stereoisomers exist (meso form and two enantiomeric forms), which epimerize when the diaziridine moieties are regarded as stereogenic units due to the coupled interconversion. Here, we have investigated the epimerization between the meso and enantiomeric forms by dynamic gas chromatography. Temperature‐dependent measurements were performed, and reaction rate constants were determined using the unified equation of chromatography implemented in the software DCXplorer. The activation barriers of the epimerization were found to be ΔG≠ = 100.7 kJ mol−1 at 25°C and ΔG≠ = 104.5 kJ mol−1 at 37°C, respectively. The activation enthalpy and entropy were determined to be ΔH≠ = 70.3 ± 0.4 kJ mol−1 and ΔS≠ = −102 ± 2 J mol−1 K−1. Chirality, 2011. © 2010 Wiley‐Liss, Inc.
Cytoskeletal dynamics in response to tensile loading of mammalian axons
Authors: Chetta Joshua , Kye Cecilia , Shah Sameer B. 
Published: September 2010

AbstractIn response to an applied tensile load, axons of cultured neurons exhibit a number of morphological responses. We designed and implemented a cell stretching device to study the cellular mechanisms governing these responses. Rat sensory neurons were seeded onto a flexible silicone substrate and imaged during substrate stretch. The positions of stationary mitochondria, docked to the axonal cytoskeleton, were determined before and after 10% stretch, and used to calculate the resulting “instantaneous” strain in regions of the axon. There was dramatic heterogeneity in strain along the length of the stretched axons, particularly in regions shorter than 20 μm. The substrate was then held at 10% strain and the axons imaged for 20 min during “relaxation.” Both strain magnitude and variability were larger at small lengths in stretched axons during the initial phase of relaxation, but after 14 min, decreased to levels smaller than those seen in unstretched axons. Mitochondrial pairs in stretched axons showed uncoordinated movement with each other at all lengths, suggesting that cytoskeletal cohesion is reduced after stretch. Collectively, these data present the axonal cytoskeleton as a dynamic structure, which responds to stretch rapidly and locally. Globally, the axon behaves as a viscoelastic continuum. Below a characteristic length, though, it appears to behave as a series of independent linked elements, each with unique mechanical properties which suggests a length scale within which cytoskeletal structural elements may be altered to modulate the biomechanical response of the axon. Finally, testable hypotheses of strain accomodation in the axon are suggested. © 2010 Wiley‐Liss, Inc.