bluuebunny/crossref_metadata_2025_split huggingface dataset:
<i>In vitro</i> regeneration potentiality of <i>Brassica</i> genotypes in differential growth regulators
Authors: Khan MMA , Robin ABM Arif Hasan Khan , Nazim-Ud-Dowla MAN , Talukder SK , Hassan L 
Published: August 2010

Petiole of six genotypes of oilseed Brassica viz. Tori-7, Sampad, Kallyania, BARI Sarisha-7, BARI Sarisha-8, and MM 20-3 were cultured in MS medium with different concentrations of BAP, NAA, and AgNO3 for callus induction and subsequent plant regeneration. The highest percentage of callus induction (91.43%) was observed in Tori-7 in the media supplemented with 2 mg/L BAP, 0.1 mg/L NAA and 2.0 mg/L AgNO3. Calli were maintained in order to get sufficient number of regenerants. With the increased concentration of BAP, the highest percentage (57.14) of regenerants were found in Tori-7 followed by Sampad (33.13%) and BARI Sarisha-8 (31.42%) in MS media supplemented with 2.5 mg/L BAP, 0.1 mg/L NAA and 2.0 mg/L AgNO3. Root formation from the regenerants was found best in half MS medium supplemented with 0.5 mg/L NAA in genotype Tori-7. Regenerated plantlets of four genotypes (Tori-7, BARI Sarisha-8, Kallyania, BARI Sarisha-7) were successfully established in the field.Keywords: AgNO3; BAP; Brassica; NAA; regeneration. DOI: 10.3329/bjar.v35i2.5881Bangladesh J. Agril. Res. 35(2) : 189-199, June 2010
Kinetic studies and predictions on the hydrolysis and aminolysis of esters of 2-S-phosphorylacetates
Authors: Trmčić Milena , Hodgson David R W 
Published: August 2010

Background: Heterobifunctional cross-linking agents are useful in both protein science and organic synthesis. Aminolysis of reactive esters in aqueous systems is often used in bioconjugation chemistry, but it must compete against hydrolysis processes. Here we study the kinetics of aminolysis and hydrolysis of 2-S-phosphorylacetate ester intermediates that result from displacement of bromide by a thiophosphate nucleophile from commonly used bromoacetate ester cross-linking agents.Results: We found cross-linking between uridine-5′-monophosphorothioate and D-glucosamine using N-hydroxybenzotriazole and N-hydroxysuccinimde bromoacetates to be ineffective. In order to gain insight into these shortfalls, 2-S-(5′-thiophosphoryluridine)acetic acid esters were prepared using p-nitrophenyl bromoacetate or m-nitrophenyl bromoacetate in combination with uridine-5′-monophosphorothioate. Kinetics of hydrolysis and aminolysis of the resulting p- and m-nitrophenyl 2-S-(5′-thiophosphoryluridine)acetates were determined by monitoring the formation of phenolate ions spectrophotometrically as a function of pH. The p- and m-nitrophenyl 2-S-(5′-thiophosphoryluridine)acetates showed similar reactivity profiles despite the significant difference in the pKaH values of their nitrophenolate leaving groups. Both were more reactive with respect to hydrolysis and aminolysis in comparison to their simple acetate progenitors, but their calculated selectivity towards aminolysis vs hydrolysis, while reasonable, would not lead to clean reactions that do not require purification. Extrapolations of the kinetic data were used to predict leaving group pKa values that could lead to improved selectivity towards aminolysis while retaining reasonable reaction times.Conclusions: Both p- and m-nitrophenyl 2-S-(5′-thiophosphoryluridine)acetates show some selectivity towards aminolysis over hydrolysis, with the m-nitrophenolate system displaying slightly better selectivity. Extrapolation of the data for hydrolysis and aminolysis of these esters suggests that the use of readily accessible trifluoroethyl 2-S-(5′-thiophosphoryluridine)acetate with a leaving group pKaH of 12.4 should afford better selectivity while maintaining reasonable reaction times. Kinetically, p- and m-nitrophenyl 2-S-(5′-thiophosphoryluridine)acetates show similar properties to o-nitrophenyl 2-S-ethylacetate, and show no evidence for intramolecular catalysis of hydrolysis or aminolysis by the phosphoryl groups.
Hot‐Pressed ZrB2 Ceramics With Composite Additives of Zr and B4C
Authors: Wang Xin‐Gang , Guo Wei‐Ming , Kan Yan‐Mei , Zhang Guo‐Jun 
Published: August 2010

AbstractThis work pointed out a new approach to get dense ZrB2 ceramics by forming refractory second phases through adding reactive composite additives. With the combination of Zr and B4C additives at a 3:1 molar ratio, the densification, microstructure, and mechanical properties of hot‐pressed ZrB2 ceramics were investigated. The Zr reacted with B4C at relatively low temperature of 1400 °C to form the secondary ultra‐high‐temperature ZrB2 and ZrC phases with high sinterability, which would be beneficial to improve the densification and maintain the high‐temperature properties of ZrB2 ceramics. For comparison, the separate effects of B4C or Zr additive on densification and microstructures of ZrB2 ceramics were also investigated.
Failure of Alumina in Torsion Tests
Authors: Schwind Thomas , Fünfschilling Stefan , Kerscher Eberhard , Lang Karl‐Heinz , Oberacker Rainer , Hoffmann Michael J. , Fett Theo 
Published: August 2010

AbstractFatigue behavior under cyclic torsion loading shows a complicated dependency between the number of cycles to failure Nf and the height of the applied load σappl. A recently published result is chosen for which three clearly different regions are observed in which the normally straight log(Nf)‐log(σ) plot shows different slopes. Whereas the high‐stress region near the torsion strength can be interpreted as normal mode‐I failure of randomly oriented surface cracks, the steep part may be understood as the consequence of friction degradation at grinding cracks which are under pure mode‐II and mode‐III loading. At lowest loads, quasi‐static subcritical crack growth support has to be expected with its commonly higher load exponents.
Formation of Aluminum Nitride Coatings at Low Temperature
Authors: Adaszko Andrew , Sercombe Timothy 
Published: August 2010

AbstractA method has been developed that produces an AlN coating on an aluminum substrate at 540 °C. It builds on the techniques previously reported (D. Kent, G. B. Schaffer, T. B. Sercombe, J. Drennan, Scripta Mater. 2006, 54, 2125), but uses aluminum powder which reduced the reaction time and required less stringent atmosphere control. Initially, the nitride formed as a shell round the particles and was accompanied by the filling of the interstitial pores by a secondary aluminum. At longer times, both the powder and the secondary aluminum nitrided, resulting in a relatively dense coating.
Nucleation Kinetics and Microstructure Evolution of Traveling ASTM F75 Droplets
Authors: Roy Sudesna , Ando Teiichi 
Published: August 2010

AbstractA method is devised for the prediction and control of the nucleation kinetics and solidification microstructure of traveling droplets of a cobalt‐base biocompatible alloy ASTM F75. Mono‐size droplets produced by the uniform‐droplet spray (UDS) process (a capillary jet breakup process) are quenched on substrates at different flight distances to determine nucleation distance from the splat morphology. Using the nucleation temperatures estimated from the splat morphology as references, the nucleation kinetics of F75 droplets is predicted and presented in the form of a continuous‐cooling transformation diagram. Cooling 300 µm F75 UDS droplets in argon gas resulted in an estimated supercooling of 132 K and formation of a well‐defined dendritic microstructure, whereas cooling the same droplets in helium gas produced a larger supercooling of 377 K and a microcrystalline structure indicative of dendrite fragmentation. This process, with stringent control of nucleation kinetics, can produce F75 balls with a rapid solidification microstructure suitable for bio‐implant applications.
Nanoindentation, Modeling, and Toughening Effects of Zirconia/Organic Nanolaminates
Authors: Zlotnikov Igor , Dorogoy Avraham , Shilo Doron , Gotman Irena , Gutmanas Elazar Y. 
Published: August 2010

AbstractThe present research is motivated by the remarkable toughness of natural nanostructured composites, specifically nacre, whose highly regular “brick‐and‐mortar” structure is composed of alternating layers of aragonite sheets separated by thin layers of organic material. Robust multilayer zirconium oxide (ZrO2)‐organic nanolaminates are deposited on Si wafers. Organic layers are synthesized employing layer‐by‐layer (LbL) deposition of alternating polyanion (PSS) and polycation (PAH) sublayers. Zirconia layers are deposited on LbL organic films employing magnetron sputtering from ZrO2 target and characterized employing TEM and XRD. Hardness and elastic modulus of the obtained nanostructures are measured employing nanoindentation technique. Yield stress of both constituents is obtained by fitting finite element (FE) nanoindentation simulations to nanoindentation measurements. Using the obtained mechanical data, the toughening of multilayered nanostructure relative to bulk zirconia is shown numerically by crack shielding mechanism that is demonstrated employing FE simulations. The higher toughness of the nanolaminates is also demonstrated by controlled scratch test.
Hierarchical ZnS‐In2S3‐CuS Nanospheres with Nanoporous Structure: Facile Synthesis, Growth Mechanism, and Excellent Photocatalytic Activity
Authors: Li Yingxuan , Chen Gang , Wang Qun , Wang Xu , Zhou Ankun , Shen Zaoyu 
Published: August 2010

AbstractWithout using any templates or surfactants, hierarchical ZnS‐In2S3‐CuS nanospheres with nanoporous structure are successfully synthesized via a simple and convenient process. The nanospheres are aggregations of densely packed nanoparticles and nanorods. Different to the oriented attachment (OA) mechanism reported in the literature, the formation of these nanorods is believed to follow a lateral OA mechanism (nanoparticles attach along the direction perpendicular to the crystallographic axes with lateral planes as the juncture) based on the experimental data. This process could be a general phenomenon and would provide a new insight into the OA mechanism. A detailed time‐resolved TEM kinetic study of the formation of the complex structure is shown. The dipole mechanism and electric field‐induced growth are found to be responsible for the final architecture. Photocatalytic activities for water splitting are investigated under visible‐light irradiation (λ > 400 nm) and an especially high photocatalytic activity (apparent yield of 22.6% at 420 nm) is achieved by unloaded ZnIn0.25Cu0.02S1.395 prepared at 180 °C for 18 h because of their high crystallinity, large pore volume, and the presence of nanorods with special microstructures.
Silver Surface Iodination for Enhancing the Conductivity of Conductive Composites
Authors: Yang Cheng , Xie Yu‐Tao , Yuen Matthew Ming‐Fai , Xu Bing , Gao Bo , Xiong Xiaomin , Wong C. P. 
Published: August 2010

AbstractThe electrical conductivity of a silver microflake‐filled conductive composites is dramatically improved after a filler surface treatment. By a simple iodine solution treatment, nonstoichiometric silver/silver iodide nanoislands form on the silver filler surface. Evidence of the decrease of surface silver oxide species is provided by TOF‐SIMS and the redox property of the nanoclusters is studied using cyclic voltammetry and TOF‐SIMS depth profile analyses. The redox property of the nanoclusters on silver flakes helps enhance the electrical conductivity of the conductive composites. The electrical resistivity of the improved conductive composites is measured by four‐point probe method; the reliability of the printed thin film resistors is evaluated by both the 85 °C/85% relative humidity moisture exposure and the −40 ∼ 125 °C thermal cycling exposure. The conductive composite printed radio frequency identification (RFID) antennas with 27.5 wt% of the modified silver flake content show comparable performance in the RFID tag read range versus copper foil antennas, and better than those commercial conductive adhesives that require much higher silver content (i.e., 80 wt%). This work suggests that a surface chemistry method can significantly reduce the percolation threshold of the loading level of the silver flakes and improve the electrical conductivity of an important printed electronic passive component.
n‐Type Organic Semiconductors in Organic Electronics
Authors: Anthony John E. , Facchetti Antonio , Heeney Martin , Marder Seth R. , Zhan Xiaowei 
Published: August 2010

AbstractOrganic semiconductors have been the subject of intensive academic and commercial interest over the past two decades, and successful commercial devices incorporating them are slowly beginning to enter the market. Much of the focus has been on the development of hole transporting, or p‐type, semiconductors that have seen a dramatic rise in performance over the last decade. Much less attention has been devoted to electron transporting, or so called n‐type, materials, and in this paper we focus upon recent developments in several classes of n‐type materials and the design guidelines used to develop them.
Iron(III) Chloride‐Catalyzed Direct Sulfonylation of Alcohols with Sodium Arenesulfinates
Authors: Reddy M. Amarnath , Reddy P. Surendra , Sreedhar B. 
Published: August 2010

AbstractA new protocol for the direct sulfonylation of benzylic, allylic and homoallylic alcohols with sodium arenesulfinates is described by using iron(III) chloride as a catalyst and chlorotrimethylsilane as an additive. This method requires no preactivation of alcohols. Surprisingly in the reaction with homoallyl alcohols nucleophilic addition of sulfinate anion, occurs at the terminal double bond instead of nucleophic substitution at the alcohol.
Enantioselective Carbonyl‐Ene Reactions of Trifluoropyruvate in Ionic Liquid via a Recyclable Indium(III)‐Pybox Complex
Authors: Zhao Jun Feng , Tan Boon Hong , Zhu Ming Kui , Tjan Teguh Budiono W. , Loh Teck Peng 
Published: August 2010

AbstractA highly enantioselective carbonyl‐ene reaction of trifluoropyruvate catalyzed by a recyclable indium(III)‐pybox complex in ionic liquid afforded trifluoromethyl‐containing tertiary homoallylic alcohols with excellent yields (up to 98%) and enantioselectivities (up to 98% ee). Notably, this catalytic system can be recycled up to seven cycles.
Zinc‐Catalyzed Domino Hydroamination–Alkyne Addition
Authors: Biyikal Mustafa , Porta Marta , Roesky Peter W. , Blechert Siegfried 
Published: August 2010

AbstractThe first zinc‐catalyzed one‐step synthesis of quaternary propargylamines with four different substituents is described. The domino hydroamination–alkyne addition reaction gives access to functionalized propargylamines under mild conditions.
2,2′‐Bis[bis(3,5‐di‐tert‐butyl‐4‐methoxyphenyl)phosphino]‐6,6′‐dimethoxy‐1,1′‐biphenyl in Intramolecular Rhodium(I)‐Catalyzed Asymmetric Pauson–Khand‐Type Reactions
Authors: Kim Dong Eun , Ratovelomanana‐Vidal Virginie , Jeong Nakcheol 
Published: August 2010

AbstractA cationic rhodium(I)/2,2′‐bis[bis(3,5‐di‐tert‐butyl‐4‐methoxyphenyl)phosphino]‐6,6′‐dimethoxy‐1,1′‐biphenyl (DTBM‐MeO‐BIPHEP) catalyst was highly efficient for the asymmetric catalytic Pauson–Khand reaction, especially for those substrates containing aryl group‐substituted alkynes. The formation of the products that were derived from a β‐hydride eliminated intermediate 5 was completely suppressed over a wide range of substrates. This reaction was a serious process competing reaction with the migratory CO insertion that led to the Pauson–Khand reaction product and often substantially ruined the chemical yield of the Pauson–Khand reaction. The advantages of this system were clearly demonstrated for previously troublesome substrates, N‐tosyl‐ (1b) and malonate‐tethered 1,6‐enynes (1c), that exhibited a higher enantioselectivity without a loss in the chemical yields. The obvious beneficial effects were attributed to the synergic effect of various factors, such as the electron density of the phosphorus of the ligand, the dihedral angles of the atropisomeric ligand, and the substitution on the phosphine aryl rings which play a crucial role in the stereochemical outcome of Rh‐catalyzed Pauson–Khand reaction.
Novel Palladium‐Catalysed Hydroamination of Myrcene and Catalyst Separation by Thermomorphic Solvent Systems
Authors: Behr Arno , Johnen Leif , Rentmeister Nils 
Published: August 2010

AbstractHydroamination is an elegant and atom economical reaction to convert alkenes into amines. One of the few technical realisations of this reaction is the hydroamination of myrcene to diethylgeranylamine, an important precursor of (−)‐menthol. However, this so‐called “Takasago process” is catalysed by high amounts of alkali metals, especially lithium, which makes it a relatively expensive approach. In the present work, the hydroamination of myrcene with morpholine is catalysed by palladium complexes with bidentate ligands such as bis(diphenylphosphino)butane (DPPB) or bis(2‐diphenylphosphinophenyl) ether (DPEphos). The systematic optimisation of the reaction parameters under single‐phase conditions led to yields of the 1,4‐adducts of higher than 90%. The only side products proved to be the telomers of myrcene, whose formation could be decreased by using appropriate reaction conditions. The method of temperature‐dependent solvent systems was successfully applied to separate the palladium catalyst from the amines with a palladium leaching lower than 1.0%.
Highly Enantioselective One‐Pot Copper‐Catalyzed 1,4 Addition/Organocatalyzed α‐Substitution of Enals
Authors: Quintard Adrien , Alexakis Alexandre 
Published: August 2010

AbstractThe asymmetric copper‐catalyzed addition of dialkylzinc to enals followed by organocatalyzed one‐pot aldehyde α‐functionalization has been accomplished providing CC, CCl or CF bond formation. These simple procedures led to the creation of two contiguous stereocenters in excellent enantioselectivities (typical ee=99%). This methodology has been applied in the synthesis of (2S,3S) isomer of Valnoctamide®.
The Efficient and Enantiospecific Total Synthesis of Cyclopenta[b]phenanthrenes Structurally‐Related to Neurosteroids
Authors: Qian Mingxing , Covey Douglas F. 
Published: August 2010

AbstractWe report an efficient synthesis of cyclopenta[b]phenanthrenes functionalized at C‐3 and C‐8 from an optically pure Hajos–Parrish ketone. The key step is a neutral alumina‐catalyzed Michael addition of a Hajos–Parrish ketone derivative (4) to 1,7‐octadien‐3‐one (2) in 98% yield. This Michael addition product went through Krapcho decarbomethoxylation, aldol condensation, lithium liquid ammonia reduction, Wacker oxidation and acid‐catalyzed cyclization to form cyclopenta[b]phenanthrene (1a) in 37% overall yield for the 7 steps.
Gerichtete Evolution stereoselektiver Enzyme: Eine ergiebige Katalysator‐Quelle für asymmetrische Reaktionen
Authors: Reetz Manfred T. 
Published: August 2010

AbstractAsymmetrische Katalyse spielt eine Schlüsselrolle in der modernen synthetischen organischen Chemie, wobei künstliche Katalysatoren und Enzyme die zwei wichtigsten Optionen darstellen. Die Verwendung von Enzymen in der organischen Chemie und Biotechnologie hat in der zweiten Hälfte des vergangenen Jahrhunderts stark zugenommen, oft blieb jedoch der Anwendungsbereich aus mehreren Gründen eingeschränkt. Dazu gehören begrenzte Substratakzeptanz, geringe oder fehlende Stereoselektivität, unzureichende Stabilität und manchmal Produktinhibierung. Während der vergangenen 15 Jahre wurde die genetische Technik der gerichteten Evolution so weit entwickelt und verfeinert, dass all diese Probleme angegangen und in der Regel gelöst werden können. Sie basiert auf wiederholende Zyklen von Genmutagenese, Expression und Screening (oder Selektion). Der vorliegende Aufsatz fokussiert auf gerichtete Evolution stereoselektiver Enzyme, ein fundamental neuer Ansatz zur asymmetrischen Katalyse. Der Schwerpunkt liegt auf Methodenentwicklung in dem Bestreben, diese Art der Katalysator‐Optimierung einfacher, schneller und effizienter als in der Vergangenheit zu gestalten. Die neueren Methoden bescheren dem Chemiker und dem Biotechnologen robuste und selektive Katalysatoren für eine Vielzahl von nützlichen Anwendungen.
Exploiting Cavities in Supramolecular Gels
Authors: Foster Jonathan A. , Steed Jonathan W. 
Published: August 2010

AbstractEndowing supramolecular gelators with cavities opens up a number of opportunities not possible with other gel systems. The well‐established host–guest chemistry of cavitands can be utilized to build up and break down gel structures, introduce responsive functionalities, or enhance selectivity in applications such as catalysis and extraction. Cavity‐containing gelators provide an excellent case study for how different aspects of supramolecular chemistry can be used intelligently to create responsive materials.
What Kind of “Soft Materials” Can We Design from Molecular Gels?
Authors: Dawn Arnab , Shiraki Tomohiro , Haraguchi Shuichi , Tamaru Shun‐ichi , Shinkai Seiji 
Published: August 2010

AbstractSince their discovery, over the years, molecular gels have been constantly drawing the attention of chemists from various scientific fields. Their structural softness together with the orderliness at the molecular level provides such molecules immense potential for the amplification of their properties. Using this chemistry, one can easily realize a macroscopic outcome from a molecular level modulation. This phenomenon is governed by the principle of supramolecular interactions that introduce a unique “reversibility” to the system. The new generation of gel chemistry is now tending more towards the development of new attractive functions to create smart materials for achieving outstanding response or unprecedented selectivity over a process. However, for the successful implementation of this mission, it is really essential to correlate gel functions with their structures. This focus review is an attempt to find such a correlation, which can motivate and stimulate this existing field towards precisely designing molecular gels for the desired functions.
Two Robust Porous Metal–Organic Frameworks Sustained by Distinct Catenation: Selective Gas Sorption and Single‐Crystal‐to‐Single‐Crystal Guest Exchange
Authors: Yang Rui , Li Lei , Xiong Ying , Li Jian‐Rong , Zhou Hong‐Cai , Su Cheng‐Yong 
Published: August 2010

AbstractAssembly of copper(I) halide with a new tripodal ligand, benzene‐1,3,5‐triyl triisonicotinate (BTTP4), afforded two porous metal–organic frameworks, [Cu2I2(BTTP4)]⊃2 CH3CN (1⋅2 CH3CN) and [CuBr(BTTP4)]⊃(CH3CN⋅CHCl3⋅H2O) (2⋅solvents), which have been characterized by IR spectroscopy, thermogravimetry (TG), single‐crystal, and powder X‐ray diffraction (PXRD) methods. Compound 1.CH3CN is a polycatenated 3D framework that consists of 2D (6,3) networks through inclined catenation, whereas 2 is a doubly interpenetrated 3D framework possessing the ThSi2‐type (ths) (10,3)‐b topology. Both frameworks contain 1D channels of effective sizes 9×12 and 10×10 Å2, which amounts to 43 and 40 % space volume accessible for solvent molecules, respectively. The TG and variable‐temperature PXRD studies indicated that the frameworks can be completely evacuated while retaining the permanent porosity, which was further verified by measurement of the desolvated complex [Cu2I2(BTTP4)] (1′). The subsequent guest‐exchange study on the solvent‐free framework revealed that various solvent molecules can be adsorbed through a single‐crystal‐to‐single‐crystal manner, thus giving rise to the guest‐captured structures [Cu2I2(BTTP4)]⊃C6H6 (1.benzene), [Cu2I2(BTTP4)]⊃2 C7H8 (1.2toluene), and [Cu2I2(BTTP4)]⊃2 C8H10 (1.2ethyl benzene). The gas‐adsorption investigation disclosed that two kinds of frameworks exhibited comparable CO2 storage capacity (86–111 mL g−1 at 1 atm) but nearly none for N2 and H2, thereby implying its separation ability of CO2 over N2 and H2. The vapor‐adsorption study revealed the preferential inclusion of aromatic guests over nonaromatic solvents by the empty framework, which is indicative of selectivity toward benzene over cyclohexane.