bluuebunny/crossref_metadata_2025_split huggingface dataset:
Collective Synthesis of Cladiellins Based on the Gold‐Catalyzed Cascade Reaction of 1,7‐Diynes
Authors: Yue Guozong , Zhang Yun , Fang Lichao , Li Chuang‐chuang , Luo Tuoping , Yang Zhen 
Published: January 2014

AbstractThe cladiellin family of natural products, which includes molecules with various biological activities, continues to invite new synthetic studies. A gold‐catalyzed tandem reaction of 1,7‐diynes to construct the 6‐5‐bicyclic ring systems that are present in a number of natural products was developed. This reaction was applied as the key step to realize the formal and total syntheses of nine members of the cladiellin family in an enantio‐ and diastereoselective manner. This modular and efficient approach could also be used for the construction of other cladiellins, as well as their analogues, for follow‐up studies.
Turning Regioselectivity into Stereoselectivity: Efficient Dual Resolution of P‐Stereogenic Phosphine Oxides through Bifurcation of the Reaction Pathway of a Common Intermediate
Authors: Nikitin Kirill , Rajendran Kamalraj V. , Müller‐Bunz Helge , Gilheany Declan G. 
Published: January 2014

AbstractSynthetic routes that provide facile access to either enantiomeric form of a target compound are particularly valuable. The crystallization‐free dual resolution of phosphine oxides that gives highly enantioenriched materials (up to 94 % ee) in excellent yields is reported. Both enantiomeric oxides have been prepared from a single intermediate, (RP)‐alkoxyphosphonium chloride, which is formed in the course of a selective dynamic kinetic resolution using a single enantiomer of menthol as the chiral auxiliary. The origin of the dual stereoselectivity lies in bifurcation of the reaction pathway of this intermediate, which works as a stereochemical railroad switch. Under controlled conditions, Arbuzov‐type collapse of this intermediate proceeds through CO bond fission with retention of the configuration at the phosphorus center. Conversely, alkaline hydrolysis of the PO bond leads to the opposite SP enantiomer.
Iridium‐Catalyzed Intermolecular Azide–Alkyne Cycloaddition of Internal Thioalkynes under Mild Conditions
Authors: Ding Shengtao , Jia Guochen , Sun Jianwei 
Published: January 2014

AbstractAn iridium‐catalyzed azide–alkyne cycloaddition reaction (IrAAC) of electron‐rich internal alkynes is described. It is the first efficient intermolecular AAC of internal thioalkynes. The reaction exhibits remarkable features, such as high efficiency and regioselectivity, mild reaction conditions, easy operation, and excellent compatibility with air and a broad spectrum of organic and aqueous solvents. It complements the well‐known CuAAC and RuAAC click reactions.
Mesenchymal‐Mode Migration Assay and Antimetastatic Drug Screening with High‐Throughput Microfluidic Channel Networks
Authors: Zhang Yuanqing , Zhang Weijia , Qin Lidong 
Published: January 2014

AbstractIncreasing evidence shows that activated mesenchymal migration is a key process of the metastatic cascade. Cancer cells usually gain such migratory capability through an epithelial‐to‐mesenchymal transition. Herein we present a high‐throughput microfluidic device with 3120 microchambers to specifically monitor mesenchymal migration. Through imaging of the whole chip and statistical analysis, we can evaluate the two key factors of velocity and percentage related to cell migratory capacity at different cell densities in culture. We also used the device to screen antimetastatic drugs for their inhibition of mesenchymal migration and prevention of metastatic malignancy. This device will provide an excellent platform for biologists to gain a better understanding of cancer metastasis.
Quantitative Analysis of Location‐ and Sequence‐Dependent Deamination by APOBEC3G Using Real‐Time NMR Spectroscopy
Authors: Furukawa Ayako , Sugase Kenji , Morishita Ryo , Nagata Takashi , Kodaki Tsutomu , Takaori‐Kondo Akifumi , Ryo Akihide , Katahira Masato 
Published: January 2014

AbstractThe human antiretroviral factor APOBEC3G (A3G) deaminates the newly synthesized minus strand of the human immunodeficiency virus 1 (HIV‐1), which results in the abolition of the infectivity of virus‐infectivity‐factor (Vif)‐deficient HIV‐1 strains.1–6 A unique property of A3G is that it deaminates a CCC hot spot that is located close to the 5′ end more effectively than one that is less close to the 5′ end. However, the mechanism of this process is elusive as it includes nonspecific binding of A3G to DNA and sliding of A3G along the DNA strand. Therefore, this process cannot be analyzed by existing methods using the Michaelis–Menten theory. A new real‐time NMR method has been developed to examine the nonspecific binding and the sliding processes explicitly, and it was applied to the analysis of the deamination by A3G. As a result, the location‐dependent deamination can be explained by a difference in the catalytic rates that depend on the direction of the approach of A3G to the target cytidine. Real‐time NMR experiments also showed that A3G deaminates CCCC tandem hotspots with little redundancy, which suggests that A3G efficiently mutates many CCC hotspots that are scattered throughout the HIV‐1 genome.
Substrate‐Directed Hydroacylation: Rhodium‐Catalyzed Coupling of Vinylphenols and Nonchelating Aldehydes
Authors: Murphy Stephen K. , Bruch Achim , Dong Vy M. 
Published: January 2014

AbstractWe report a protocol for the hydroacylation of vinylphenols with aryl, alkenyl, and alkyl aldehydes to form branched products with high selectivity. This cross‐coupling yields α‐aryl ketones that can be cyclized to benzofurans, and it enables access to eupomatenoid natural products in four steps or less from eugenol. Excellent reactivity and high levels of regioselectivity for the formation of the branched products were observed. We propose that aldehyde decarbonylation is avoided by the use of an anionic directing group on the alkene and a diphosphine ligand with a small bite angle.
A Core‐Expanded Subphthalocyanine Analogue with a Significantly Distorted Conjugated Surface and Unprecedented Properties
Authors: Shimizu Soji , Nakano Shota , Kojima Ayaka , Kobayashi Nagao 
Published: January 2014

AbstractThe introduction of a seven‐membered‐ring unit in the place of a five‐membered‐ring unit in the structure of subphthalocyanine resulted in significant distortion of the bowl‐shaped structure of the conjugated molecule as well as the following unprecedented properties: the preferential formation of the axially fluoro substituted species, the fluttering‐dynamic‐motion‐induced rapid exchange of P and M enantiomers, markedly split Q‐band absorption, and a clear difference in the ring‐current effects arising from the convex and concave surfaces.
Vibrational Spectroscopy of the Dehydrogenated Uracil Radical by Autodetachment of Dipole‐Bound Excited States of Cold Anions
Authors: Liu Hong‐Tao , Ning Chuan‐Gang , Huang Dao‐Ling , Wang Lai‐Sheng 
Published: January 2014

AbstractMolecules with large enough dipole moments can bind an electron by the dipole field, which has little effect on the molecular core. A molecular anion can be excited to a dipole‐bound state, which can autodetach by vibronic coupling. Autodetachment spectroscopy of a complex anion cooled in a cryogenic ion trap is reported. Vibrational spectroscopy of the dehydrogenated uracil radical is obtained by a dipole‐bound state with partial rotational resolution. Fundamental frequencies for 21 vibrational modes of the uracil radical are reported. The electron affinity of the uracil radical is measured accurately to be 3.4810±0.0006 eV and the binding energy of the dipole‐bound state is measured to be 146±5 cm−1. The rotational temperature of the trapped uracil anion is evaluated to be 35 K.
A 1D/2D Helical CdS/ZnIn2S4 Nano‐Heterostructure
Authors: Xu Biao , He Peilei , Liu Huiling , Wang Pengpeng , Zhou Gang , Wang Xun 
Published: January 2014

AbstractMultidimensional nano‐heterostructures (NHSs) that have unique dimensionality‐dependent integrative and synergic effects are intriguing but still underdeveloped. Here, we report the first helical 1D/2D epitaxial NHS between CdS and ZnIn2S4. Experimental and theoretical studies reveal that the mismatches in lattice and dangling bonds between 1D and 2D units govern the growth procedure. The resulting well‐defined interface induces the delocalized interface states, thus facilitate the charge transfer and enhance the performance in the photoelectrochemical cells. We foresee that the mechanistic insights gained and the electronic structures revealed would inspire the design of more complex 1D/2D NHSs with outstanding functionalities.
Stereospecific Nickel‐Catalyzed Cross‐Coupling Reactions of Alkyl Grignard Reagents and Identification of Selective Anti‐Breast‐Cancer Agents
Authors: Yonova Ivelina M. , Johnson A. George , Osborne Charlotte A. , Moore Curtis E. , Morrissette Naomi S. , Jarvo Elizabeth R. 
Published: January 2014

AbstractAlkyl Grignard reagents that contain β‐hydrogen atoms were used in a stereospecific nickel‐catalyzed cross‐coupling reaction to form C(sp3)C(sp3) bonds. Aryl Grignard reagents were also utilized to synthesize 1,1‐diarylalkanes. Several compounds synthesized by this method exhibited selective inhibition of proliferation of MCF‐7 breast cancer cells.
Highly Efficient Electrocatalysts for Oxygen Reduction Based on 2D Covalent Organic Polymers Complexed with Non‐precious Metals
Authors: Xiang Zhonghua , Xue Yuhua , Cao Dapeng , Huang Ling , Chen Jian‐Feng , Dai Liming 
Published: January 2014

AbstractA class of 2D covalent organic polymers (COPs) incorporating a metal (such as Fe, Co, Mn) with precisely controlled locations of nitrogen heteroatoms and holes were synthesized from various N‐containing metal–organic complexes (for example, metal–porphyrin complexes) by a nickel‐catalyzed Yamamoto reaction. Subsequent carbonization of the metal‐incorporated COPs led to the formation of COP‐derived graphene analogues, which acted as efficient electrocatalysts for oxygen reduction in both alkaline and acid media with a good stability and free from any methanol‐crossover/CO‐poisoning effects.
Poly(HEMA)/cyclodextrin‐based hydrogels for subconjunctival delivery of cyclosporin A
Authors: Başbağ A. Berna , Gümüşderelioğlu Menemşe , Şimşek Murat , Güner Ali 
Published: January 2014

ABSTRACTTo enhance the solubility and ocular permeability of immunosuppressive agent, cyclosporine A (CsA), three types of delivery systems were prepared using (2‐hydroxypropyl)‐β‐cyclodextrin (HPβCD), and 2‐hydroxyethyl methacrylate (HEMA). Those systems are (i) hydrogels of HPβCD with crosslinking agent ethylene glycol diglycidylether, (ii) poly(HEMA) hydrogels, and (iii) different amounts of HPβCD‐containing poly(HEMA) hydrogels indicated as poly(HEMA‐co‐HPβCD). In the presence of HEMA, hydrogels have desired mechanical integrity with lower equilibrium content than that of hydrogels without HEMA. CsA was loaded into the HPβCD‐based hydrogels by embedding from its aqueous suspensions in higher amounts than that of the poly(HEMA) hydrogels that were loaded by CsA–HPβCD complex solution. Although the poly(HEMA) hydrogels are releasing total CsA in 3 days, long‐term release was realized from HPβCD‐based hydrogels. For subconjunctival administration, regarding to the amounts of loaded CsA, release profiles, and mechanical integrity, the most suitable system is poly(HEMA‐co‐HPβCD) hydrogels in high HPβCD content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40397.
Thermotropic systems with fixed domains exhibiting enhanced overheating protection performance
Authors: Weber Andreas , Resch Katharina 
Published: January 2014

ABSTRACTWithin this study, a time saving photo‐initiated miniemulsion polymerization process (duration of polymerization was 15 min) was established in order to encapsulate a paraffin wax with an acrylate polymer shell. The obtained freeze‐dried latex was an off‐white powder exhibiting spherical particles with mean diameters around 400 nm and a concentration of paraffin wax around 56%. Mixing the reaction product with a UV‐curable resin matrix resulted in thermotropic overheating protection glazings with high light‐shielding efficiency. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2014,131, 40417.
Cellulose nanofibers prepared from TEMPO‐oxidation of kraft pulp and its flocculation effect on kaolin clay
Authors: Jin Liqiang , Wei Yanwei , Xu Qinghua , Yao Wenrun , Cheng Zhengliang 
Published: January 2014

ABSTRACTCellulose nanofibers were prepared using TEMPO/NaBr/NaClO oxidation of kraft pulp and successive ultrasonic treatment, and the properties were characterized by conductimetric titration, X‐ray diffraction, and atomic force microscopy. The resulting product was then applied as an anionic microparticle to constitute a microparticulate system with cationic polyacrylamide (CPAM), to induce the flocculation of the kaolin clay suspension. The flocculation effect was evaluated by determining the relative turbidity of clay suspension. The results showed that the obtained cellulose nanofibers had cellulose I structure with higher crystallinity than that of the kraft pulp, and their cross‐sectional dimension was in the range of 3–5 nm. They had more negative zeta potential at neutral and alkaline conditions. It was found that the microparticulate system showed high flocculation effect on kaolin clay at a very low level of nanofiber addition, and a high shear level after CPAM addition was helpful for the flocculation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40450.
Thieno[3,4‐c]pyrrole‐4,6‐dione‐Based Small Molecules for Highly Efficient Solution‐Processed Organic Solar Cells
Authors: Ha Jong‐jin , Kim Yu Jin , Park Jong‐gwang , An Tae Kyu , Kwon Soon‐Ki , Park Chan Eon , Kim Yun‐Hi 
Published: January 2014

AbstractTwo small molecules named BT‐TPD and TBDT‐TTPD with a thieno[3,4‐c]pyrrole‐4,6‐dione (TPD) unit were designed and synthesized for solution‐processed bulk‐heterojunction solar cells. Their thermal, electrochemical, optical, charge‐transport, and photovoltaic characteristics were investigated. These compounds exhibit strong absorption at 460–560 nm and low highest occupied molecular orbital levels (−5.36 eV). Field‐effect hole mobilities of these compounds are 1.7–7.7×10−3 cm2 V−1 s−1. Small‐molecule organic solar cells based on blends of these donor molecules and a acceptor display power conversion efficiencies as high as 4.62 % under the illumination of AM 1.5G, 100 mW cm−2.
Synthetic biology of avermectin for production improvement and structure diversification
Authors: Zhuo Ying , Zhang Tao , Wang Qi , Cruz‐Morales Pablo , Zhang Buchang , Liu Mei , Barona‐Gómez Francisco , Zhang Lixin 
Published: January 2014

AbstractNatural products are still key sources of current clinical drugs and innovative therapeutic agents. Since wild‐type microorganisms only produce natural products in very small quantities, yields of production strains need to be improved by breaking down the precise genetic and biochemical circuitry. Herein, we use avermectins as an example of production improvement and chemical structure diversification by synthetic biology. Avermectins are macrocyclic lactones produced by Streptomyces avermitilis and are well known and widely used for antiparasitic therapy. Given the importance of this molecule and its derivatives, many efforts and strategies were employed to improve avermectin production and generate new active analogues. This review describes the current status of synthetic strategies successfully applied for developing natural‐product‐producing strains and discusses future prospects for the application of enhanced avermectin production.
The human anti‐HIV antibodies 2F5, 2G12, and PG9 differ in their susceptibility to proteolytic degradation: Down‐regulation of endogenous serine and cysteine proteinase activities could improve antibody production in plant‐based expression platforms
Authors: Niemer Melanie , Mehofer Ulrich , Torres Acosta Juan Antonio , Verdianz Maria , Henkel Theresa , Loos Andreas , Strasser Richard , Maresch Daniel , Rademacher Thomas , Steinkellner Herta , Mach Lukas 
Published: January 2014

AbstractThe tobacco‐related speciesNicotiana benthamianahas recently emerged as a promising host for the manufacturing of protein therapeutics. However, the production of recombinant proteins inN. benthamianais frequently hampered by undesired proteolysis. Here, we show that the expression of the human anti‐HIV antibodies 2F5, 2G12, and PG9 inN. benthamianaleaves leads to the accumulation of discrete heavy chain‐derived degradation products of 30–40 kDa. Incubation of purified 2F5 withN. benthamianaintercellular fluid resulted in rapid conversion into the 40‐kDa fragment, whereas 2G12 proved largely resistant to degradation. Such a differential susceptibility to proteolytic attack was also observed when these two antibodies were exposed to various types of proteinases in vitro. While serine and cysteine proteinases are both capable of generating the 40‐kDa 2F5 fragment, the 30‐kDa polypeptide is most readily obtained by treatment with the latter class of enzymes. The principal cleavage sites reside within the antigen‐binding domain, the VH–CH1 linker segment and the hinge region of the antibodies. Collectively, these results indicate that down‐regulation of endogenous serine and cysteine proteinase activities could be used to improve the performance of plant‐based expression platforms destined for the production of biopharmaceuticals.
Introducing basic molecular biology to Turkish rural and urban primary school children via hands‐on PCR and gel electrophoresis activities
Authors: Selli Cigdem , Yıldırım Gokce , Kaymak Aysegul , Karacicek Bilge , Ogut Deniz , Gungor Turkan , Erem Erdem , Ege Mehmet , Bümen Nilay , Tosun Metiner 
Published: January 2014

AbstractThis study includes the results of a 2‐day education project titled “Molecular Biology Laboratory Summer School, MoBiLYO.” The project was held at a University Research Center by scientists from Department of Pharmacology and graduate students. The project was composed of introductory lectures, model construction, DNA isolation, polymerase chain reaction (PCR), and gel electrophoresis. The participants were 13‐year‐old eighth‐graders attending primary schools affiliated with Ministry of National Education in urban and rural areas of Izmir, Turkey. The purpose of this study was to introduce basic molecular biology concepts through individually performed experiments such as PCR and gel electrophoresis integrated with creative drama. The students were assessed at the beginning and the end of each project day via mini‐tests, experimental and presentation skills evaluation forms. Data showed that students' knowledge about DNA structure and basic molecular biology techniques significantly increased. On the basis of experimental and presentational skills, there was no significant difference between kids from urban and rural schools or between public and boarding public schools, whereas the average score of girls was significantly higher than that of boys. In conclusion, individually performed experiments integrated with creative drama significantly increased students' perception of complex experimental procedures on basic molecular biology concepts. Data suggests that integration of these concepts into the science and technology curriculum of Turkish primary education may support the recruitment of future scientists who can handle rapidly developing genomic techniques that will affect our everyday life. © 2014 by The International Union of Biochemistry and Molecular Biology, 42(2):114–120, 2014
Bacterial production of the fungus‐derived cholesterol‐lowering agent mevinolin
Authors: Bose Utpal , Hodson Mark P. , Shaw P. Nicholas , Fuerst John A. , Hewavitharana Amitha K. 
Published: January 2014

ABSTRACTForty‐five strains from two different species (Salinispora arenicola and Salinispora pacifica) were isolated from three different marine sponge species in the Great Barrier Reef region of Australia. We found that two of the strains of Salinispora arenicola (MV0335 and MV0029) produced mevinolin, a fungus‐derived cholesterol‐lowering agent. Compound structure was determined using an integrated approach: (a) high performance liquid chromatography‐quadrupole time‐of‐flight‐mass spectrometric analysis with multimode ionization (electrospray ionization and atmospheric pressure chemical ionization) and fast polarity switching; and (b) database searching and matching of monoisotopic masses, retention times and mass spectra of the precursor and product ions of the compounds of interest and the authentic reference standards thereof. Copyright © 2014 John Wiley & Sons, Ltd.
Identification of Pyrroloformamide as a Cytokinesis Modulator
Authors: Abreu Paula A. , Sousa Thiciana S. , Jimenez Paula C. , Wilke Diego V. , Rocha Danilo D. , Freitas Hozana P. S. , Pessoa Otília D. L. , La Clair James J. , Costa‐Lotufo Letícia V. 
Published: January 2014

AbstractDiscovered in the late 1940s, the pyrrolinonodithioles represent a family of potent disulfide‐containing natural products. Although they are understood in a synthetic and biosynthetic context, the biological role of these materials remains unresolved. To date, their activity has been suggested to arise through regulating RNA metabolism, and more recently they have been suggested to function as backup thiols for detoxification. Using materials identified through a natural products program, we now identify the biological function of one member of this family, pyrroloformamide, as an antimitotic agent acting, in part, by disrupting cytokinesis.
Adipose‐derived stromal cells grown on a hydroxyapatite scaffold can support hematopoiesis in regenerated bone marrow in vivo
Authors: Ueda Takahiro , Fujita Atsushi , Ogawa Rei , Itoh Yasuhiko , Fukunaga Yoshitaka , Shimada Takashi , Migita Makoto 
Published: January 2014

AbstractOsteoblastic cells are a key component of the bone marrow (BM) stem cell niche and help regulate hematopoietic stem cells (HSCs). We have previously demonstrated that adipose‐derived stromal cells (ADSCs) can differentiate into both osteogenic and chondrogenic cells in vitro. The current study examined whether the anatomical architecture of the BM could be regenerated in vivo by using ADSCs cultured on a hydroxyapatite (HA) scaffold. ADSCs from GFP transgenic mice were cultured in vitro on an HA scaffold. The scaffold with the attached cells was implanted subcutaneously onto the backs of C57/BL6 (Ly5.2) recipient mice. Lineage‐negative (Lin‐) Ly5.1 BM cells transduced with a lentiviral vector containing the luciferase (Luc) gene were intravenously administered to the recipient mice after lethal irradiation. Eight weeks after BM transplantation, the scaffolds were removed from the first recipient mice and subcutaneously implanted into lethally irradiated second recipient mice. The biodistribution and kinetics of Luc+ Ly5.1 cells were monitored by bioluminescence imaging and flow cytometry. Luc+ hematopoietic cells were present in the scaffolds of the secondary implanted mice for at least 8 months. Subcutaneous injection of G‐CSF resulted in wide distribution of bioluminescence signals from the original scaffolds to the whole body. Therefore, BM regenerated using ADSCs grown on an HA scaffold can support HSC populations in vivo, suggesting that a functional BM niche is reconstituted. These results may have a significant impact on the development of therapeutic strategies for various hematopoietic diseases.