bluuebunny/crossref_metadata_2025 huggingface dataset:
Protein tyrosine kinase 2 beta (PTK2B), but not focal adhesion kinase (FAK), is expressed in a sexually dimorphic pattern in developing mouse gonads
Authors: Beverdam Annemiek , Svingen Terje , Bagheri‐Fam Stefan , McClive Peter , Sinclair Andrew H. , Harley Vincent R. , Koopman Peter
Published: August 2010

Sexual reproduction is essential for the propagation and the maintenance of fitness of our species, and is dependent on the correct development of the bipotential genital ridges into testes and ovaries. Although several transcription factors, secreted signaling molecules, and their receptors have been found to be important for testis determination and early gonad development, comparatively little research has been carried out into intracellular signal transduction pathways activated during these processes. Focal adhesion kinase (FAK) and protein tyrosine kinase 2 beta (PTK2B) form one group of cytosolic tyrosine kinases that are known to be important for processes such as cell proliferation, differentiation, and motility. Here, we describe the temporal and spatial expression patterns of Fak and Ptk2b mRNA and protein during sex determination and early gonadogenesis in mouse embryos. Ptk2b mRNA and PTK2B protein were expressed in testes from 11.5 days post coitum onward, predominantly in developing Sertoli cells, in a SOX9‐dependent manner. Fak mRNA and FAK protein were expressed in gonads of both sexes at all stages examined. Our data suggest cell type‐ and stage‐specific roles for PTK2B during early testis development. Developmental Dynamics 239:2735–2741, 2010. © 2010 Wiley‐Liss, Inc.
Conservation, expression, and knockdown of zebrafish plxnb2a and plxnb2b
Authors: Perälä Nina , Peitsaro Nina , Sundvik Maria , Koivula Henri , Sainio Kirsi , Sariola Hannu , Panula Pertti , Immonen Tiina
Published: August 2010

In mice lacking Plexin B2, a receptor of the axon guidance molecules Semaphorin 4C and Semaphorin 4D, the closure of the neural tube and structural organization of the cerebellum are severely impaired. We cloned two Plexin B2 orthologs, plxnb2a and plxnb2b, in zebrafish, which is a widely used model for the development of the vertebrate central nervous system (CNS). The predicted proteins, Plexin B2a and Plexin B2b, contain all the conserved and functional domains of the plexin B‐subfamily. During embryonic development, plxnb2a is expressed, e.g., in pharyngeal arches while plxnb2b expression is more confined to neuronal structures like the cerebellum. However, both plxnb2a and plxnb2b are expressed at the midbrain–hindbrain boundary, in the otic vesicles, facial ganglia, and pectoral fins. Knockdown of both plxnb2a and plxnb2b simultaneously (>95% and 45%, respectively) resulted in normal CNS structure, axon guidance and swimming performance of the morphants. Developmental Dynamics 239:2722–2734, 2010. © 2010 Wiley‐Liss, Inc.
Zebrafish cx30.3: Identification and characterization of a gap junction gene highly expressed in the skin
Authors: Tao Liang , DeRosa Adam M. , White Thomas W. , Valdimarsson Gunnar
Published: August 2010

We have identified and characterized a zebrafish connexin, Cx30.3. Sequence similarity analyses suggested that Cx30.3 was orthologous to both mammalian Cx26 and Cx30, known to play important roles in the skin and inner ear of mammals. Analysis of mRNA expression showed that Cx30.3 was present in early embryos, and was highly abundant in skin, but also detected in other tissues including fins, inner ear, heart, and the retina. Injection of Cx30.3 cRNA into Xenopus oocytes elicited robust intercellular coupling with voltage gating sensitivity similar to mammalian Cx26 and Cx30. The similarities in functional properties and expression patterns suggest that Cx30.3, like mammalian Cx26 and Cx30, may play a significant role in skin development, hearing, and balance in zebrafish. Thus, zebrafish could potentially serve as an excellent model to study disorders of the skin and deafness that result from human connexin mutations. Developmental Dynamics 239:2627–2636, 2010. © 2010 Wiley‐Liss, Inc.
A transgenic zebrafish for monitoring in vivo microtubule structures
Authors: Asakawa Kazuhide , Kawakami Koichi
Published: August 2010

The microtubule (MT) cytoskeleton plays crucial roles in brain development by regulating the proliferation of neuronal progenitor cells, neuronal migration and axon guidance. Methods for monitoring MT in the intact brain, however, have been limited in vertebrates. Here, we report a transgenic zebrafish line for monitoring MT in vivo. This reporter line carries a transgene encoding the green fluorescent protein (GFP) ‐tagged tubulin gene linked to the upstream activating sequence (UAS), the recognition sequence of the yeast Gal4 transcriptional activator. By crossing this reporter line with appropriate transgenic Gal4 driver lines, we induced the GFP‐tagged tubulin in various cell types from the embryonic stages to the adult stage. In larvae expressing the modified tubulin, individual MT filaments and other MT structures, including the mitotic spindles in proliferating neuronal progenitor cells, were clearly visualized. Therefore, the transgenic UAS reporter line should be useful for directly monitoring MTs in the intact brain. Developmental Dynamics 239:2695–2699, 2010. © 2010 Wiley‐Liss, Inc.
Developmental expression of sideroflexin family genes in Xenopus embryos
Authors: Li Xiaojing , Han Dandan , Kin Ting Kam Richard , Guo Xiaogang , Chen Miao , Yang Yong , Zhao Hui , Chen Yonglong
Published: August 2010

Emerging evidence indicates that mitochondrial carriers are not only crucial for metabolism, but also important for embryonic development. Sideroflexin is a novel family of mitochondrial tricarboxylate carrier proteins, of which the in vivo function is largely unknown. Here, we report on the expression patterns of five sideroflexin genes in Xenopus embryos. Whole‐mount in situ hybridization analysis reveals that while sideroflexin2 is expressed in the pancreas, sideroflexin1 and 3 display a complex expression in the central nervous system, somites, pronephros, liver, and pancreas. In contrast, only a weak expression of sideroflexin4 and 5 was detected in embryonic brain. Taken together, the five sideroflexin genes show both overlapping and nonoverlapping expression during Xenopus embryogenesis. As the primary structures of the five sideroflexin proteins are also quite similar, their functional redundancy should be taken into consideration for gene targeting studies. Developmental Dynamics 239:2742–2747, 2010. © 2010 Wiley‐Liss, Inc.
Analysis of a Hand1 hypomorphic allele reveals a critical threshold for embryonic viability
Authors: Firulli Beth A. , McConville David P. , Byers III James S. , Vincentz Joshua W. , Barnes Ralston M. , Firulli Anthony B.
Published: August 2010

Loss‐of‐function analysis of the basic helix–loop–helix (bHLH) transcription factor Hand1 indicates critical roles in development. In an effort to generate a Hand1 cDNA knock‐in reporter mouse, we generated two hypomorphic alleles, which extend embryonic survival to between embryonic day (E) 10.5 and E12.5. Heart morphogenesis appears largely normal; however, hypomorphic mice display thin left ventricular myocardium and reduction in pharyngeal mesoderm. Caudal defects, large allantois, and thickened yolk sac are observed and consistent with systemic Hand1 gene deletion. Hand1 mRNA is expressed at 30% of wild‐type littermates and known Hand1‐dependent genes show intermediate expression compared with wild‐type and Hand1 null mice. Interestingly, putative bHLH partners, Hand2 and Twist1, show altered expression in both Hand1 null and hypomorphic backgrounds and intercrossing the Hand1 hypomorphic mice onto the Hand2 systemic null background exacerbates the cardiac and lateral mesoderm phenotypes. Together, these data define a critical threshold of Hand1 expression that is necessary for embryonic survival. Developmental Dynamics 239:2748–2760, 2010. © 2010 Wiley‐Liss, Inc.
Autotaxin controls caudal diencephalon‐mesencephalon development in the chick
Authors: Ohuchi Hideyo , Fukui Hitomi , Matsuyo Akane , Tomonari Sayuri , Tanaka Masayuki , Arai Hiroyuki , Noji Sumihare , Aoki Junken
Published: August 2010

The diencephalon is the embryonic anlagen of the higher integration centers of the brain. Recent studies have elucidated how the cells in the rostral diencephalon acquire their regional identities. However, the understanding of the mechanisms under which the caudal diencephalon is formed is still limited. Here we focus on the role of Autotaxin (ATX), a lysophospholipid‐generating exoenzyme, whose mRNA is detected in the caudal diencephalon. RNA interference against ATX altered the expression pattern of Pax6‐regualted genes, Tcf4, Lim1, and En1, implying that ATX is required for the maintenance of the regional identity of the caudal diencephalon and the diencephalon‐mesencephalon boundary (DMB). Furthermore, ATX‐RNAi inhibited neuroepithelial cell proliferation on both sides of the DMB. We propose a dual role of ATX in chick brain development, in which ATX not only contributes to the formation of caudal diencephalon as a short‐range signal, but also regulates the growth of mesencephalon as a long‐range signal. Developmental Dynamics 239:2647–2658, 2010. © 2010 Wiley‐Liss, Inc.
The ziwi promoter drives germline‐specific gene expression in zebrafish
Authors: Leu David H. , Draper Bruce W.
Published: August 2010

We describe here the characterization of the promoter activity of a 4.8‐kb sequence isolated from the 5′ end of the zebrafish germ cell‐specific ziwi gene. We show that this fragment is sufficient to drive heterologous gene expression specifically in germ cell starting as early as 7 days post‐fertilization, a time point when only mitotic germ cells are present in the gonad. In adult animals, we find that this fragment is sufficient to drive gene expression in all germ cells with stage‐specific differences in expression levels. In females, EGFP expression is highest in stage IB oocytes, but appreciable expression is detected in both pre‐meiotic germ cells, as well stage II–IV oocytes and mature eggs. In males, EGFP expression is highest in spermatogonial stem cells, but low levels are detected in all stages, including spermatozoa. Developmental Dynamics 239:2714–2721, 2010. © 2010 Wiley‐Liss, Inc.
Eating disorder symptomatology and substance use disorders: Prevalence and shared risk in a population based twin sample
Authors: Baker Jessica H. , Mitchell Karen S. , Neale Michael C. , Kendler Kenneth S.
Published: August 2010

Objective:

Research shows a significant association between eating disorders (ED) and substance use disorders (SUD). The objective of this study is to examine the prevalence, chronology, and possibility of shared familial risk between SUD and ED symptomatology.

Method:

Subjects included 1,206 monozygotic and 877 dizygotic adult female twins. ED symptomatology included anorexia (AN) and bulimia nervosa (BN) diagnosis, symptoms associated with diagnostic criteria, and BN symptom count. SUD included alcohol, illicit drug, and caffeine abuse/dependence. Generalized estimated equation modeling was used to examine phenotypic associations, and Choleksy decompositions were used to delineate the contribution of genes and environment to comorbidity.

Results:

There were no significant differences between SUD prevalence in women with AN and BN. Women with BN reported BN preceded SUD development while the reverse was true for AN. Twin analyses showed possible familial overlap between BN symptomatology and all SUD examined.

Discussion:

Results suggest an important difference in the chronology of EDs and SUDs. Women with BN may be turning to substances to dampen bulimic urges. Women with AN may be engaging in substance use initially in an effort to lose weight. Results also suggest familial factors contribute to the comorbidity between BN and SUD. © 2010 by Wiley Periodicals, Inc. (Int J Eat Disord 2010;)
The resource coupling role of animal foraging pits in semi‐arid woodlands
Authors: Eldridge David J.
Published: August 2010

Water is a strong driver of ecosystem function and diversity in resource‐limited drylands. Structures that alter the redistribution of water have the potential to affect vegetation pattern and productivity and the maintenance of spatial heterogeneity. We examined the role of surface foraging pits and mounds constructed by the short‐beaked echidna (Tachyglossus aculeatus) on runoff generation, sediment detention and seed capture. We speculated that pits dug into biologically crusted interspace soils would reduce overland flow and act as sinks for seed, while mounds of ejected soil would increase sediment availability. Runoff and sediment yield were examined under simulated rainfall with five levels of disturbance representing the pits and mounds of echidnas. Increasing the level of disturbance up to 47% cover of mounds and pits had no effect on time to ponding, steady‐state runoff or the coefficient of runoff. However, time to initiation of runoff, sediment removal rates and sediment concentration in runoff water increased with increasing disturbance. Pit‐to‐pit and surface‐to‐pit movements of Dodonaea viscosa seed tended to increase, while pit‐to‐surface movements tended to remain unchanged with increasing disturbance. Surface‐resident seed generally moved shorter distances with increasing disturbance. The results highlight the importance of mounds and pits of soil foraging animals for generating and trapping eroded sediment. Runoff and erosion processes may therefore provide a mechanism for coupling critical resources such as seed, water and sediment in resource‐rich patches that will contribute to the development of small‐scale heterogeneity in woodlands. Copyright © 2010 New South Wales, Australia.
The role of groundwater pumping and drought in shaping ecological futures for stream fishes in a dryland river basin of the western Great Plains, USA
Authors: Falke Jeffrey A. , Fausch Kurt D. , Magelky Robin , Aldred Angela , Durnford Deanna S. , Riley Linda K. , Oad Ramchand
Published: August 2010

Across the western Great Plains of North America, groundwater pumping for irrigated agriculture is depleting regional aquifers that sustain streamflow for native fishes. We investigated linkages between groundwater pumping from the High Plains Aquifer and stream fish habitat loss at multiple spatial scales during spring and summer 2005–2007 in the Arikaree River, eastern Colorado, USA. Monthly low‐altitude flights showed that flowing reaches were reduced from about 65 to ⩽15 km by late summer, and long permanently dry segments in the lower basin prevent recolonization. Drying occurred rapidly during summer within three 6·4‐km river segments, and patterns in habitat connectivity varied among segments owing to hydraulic conductivity. Most refuge pool habitats dried completely or lost more than half their volume, disconnecting from other pools by late summer. On the basis of these empirical habitat data, and historical groundwater and streamflow data, we constructed a MODFLOW model to predict how groundwater pumping will affect water table levels and fish habitat under three future scenarios. Under the most conservative scenario, we predicted that only 57% of refuge pools will remain in 35 years (2045), nearly all isolated in a 1·7‐km fragment of river. A water balance model indicated that maintaining current water table levels and refuge pools for fishes would require a 75% reduction in groundwater pumping, which is not economically or politically feasible. Given widespread streamflow declines, ecological futures are bleak for stream fishes in the western Great Plains, and managers will be challenged to conserve native fishes under current groundwater pumping regimes. Copyright © 2010 John Wiley & Sons, Ltd.
Effects of exposure, scrub position, and soil surface components on the hydrological response in small plots in southern Spain
Authors: Ruiz‐Sinoga J. D. , Martínez‐Murillo J. F. , Gabarrón‐Galeote M. A. , García‐Marín R.
Published: August 2010

Rangelands are a major component of the Mediterranean landscape. These environments are commonly affected by grazing, which reduces vegetation cover. Consequently, patchy vegetation patterns occur on Mediterranean hillslopes, where the bare soil is characterized by a number of surface components that are controlled by climatic conditions and exposure. The aim of this study was to assess at a fine scale the effects of exposure, scrub, and soil surface components on the hydrological response under various Mediterranean climatic conditions. A set of closed plots (each of area 1·3 m2) were established in each of three Mediterranean rangeland environments that differ in climatic conditions (humid, dry, and semiarid), but were not affected by intensive grazing. Rainfall was recorded at a meteorological station installed at each field site, and topsoil moisture was measured after every rainfall event, when run‐off was collected. The results showed that (i) run‐off was generated when topsoil moisture was close to saturation in the case of humid sites, and close to the wilting point at dry and semi‐arid sites; (ii) run‐off did not follow the same trends as rainfall and topsoil moisture along the climatic gradient because of the effects of soil surface components; (iii) the hydrological response in the plots was not clearly controlled by exposure and the location of scrub, especially at the semi‐arid site; and (iv) the differences between field sites were small because of the influence of grazing on vegetation cover and the effects of soil water repellency, both of which require further investigation. Copyright © 2010 John Wiley & Sons, Ltd.
Ecohydrological adaptation of soils following land abandonment in a semi‐arid environment
Authors: Cammeraat Erik L. H. , Cerdà Artemi , Imeson Anton C.
Published: August 2010

Representative land use types were selected in southeast Spain to investigate the redistribution of soil water in relation to vegetation development and land abandonment.

Simulated rainfall experiments were performed during 2 days on each of the four selected surfaces: ploughed, a 3‐year fallow field, a 12‐year abandoned field with shrubs and a semi‐natural field withStipa tenacissimatussocks. Each experiment consisted of five runs of artificial rain. Soil moisture dynamics were measured by time domain reflectometry (TDR), as well as runoff and ponding on the plot surface. Also the movement of the wetting front was measured after each run.

On the ploughed field, ponding and local runoff were less important with shallow and homogeneous wetting fronts. The other land uses showed increased heterogeneity in wetting front development, with soil water pockets under the plants that moved down at greater velocities than under the bare inter‐spaces. It is hypothesized thatS. tenacissimaand possiblyArtemisia herba‐albaadapt their environment by capturing water through stem–root flow systems to divert water to deeper soil layers to reduce evaporation. Furthermore it is suggested that during vegetation development soil heterogeneity increases, as expressed by the water infiltration patterns observed, and that the bare inter‐patches are important in the infiltration process. Copyright © 2010 John Wiley & Sons, Ltd.
Effect of land cover change on runoff curve number estimation in Iowa, 1832–2001
Authors: Wehmeyer Loren L. , Weirich Frank H. , Cuffney Thomas F.
Published: August 2010

Within the first few decades of European‐descended settlers arriving in Iowa, much of the land cover across the state was transformed from prairie and forest to farmland, patches of forest, and urbanized areas. Land cover change over the subsequent 126 years was minor in comparison. Between 1832 and 1859, the General Land Office conducted a survey of the State of Iowa to aid in the disbursement of land. In 1875, an illustrated atlas of the State of Iowa was published, and in 2001, the US Geological Survey National Land Cover Dataset was compiled. Using these three data resources for classifying land cover, the hydrologic impact of the land cover change at three points in time over a period of 132+ years is presented in terms of the effect on the area‐weighted average curve number, a term commonly used to predict peak runoff from rainstorms. In the four watersheds studied, the area‐weighted average curve number associated with the first 30 years of settlement increased from 61·4 to 77·8. State‐wide mapped forest area over this same period decreased 19%. Over the next 126 years, the area‐weighted average curve number decreased to 76·7, despite an additional forest area reduction of 60%. This suggests that degradation of aquatic resources (plants, fish, invertebrates, and habitat) arising from hydrologic alteration was likely to have been much higher during the 30 years of initial settlement than in the subsequent period of 126 years in which land cover changes resulted primarily from deforestation and urbanization. Published 2010. This article is a US Government work and is in the public domain in the USA.
Mono‐ and Dinuclear NiII and CoII Complexes that Feature Chelating Guanidine Ligands: Structural Characteristics and Molecular Magnetism
Authors: Roquette Pascal , König Carolin , Hübner Olaf , Wagner Arne , Kaifer Elisabeth , Enders Markus , Himmel Hans‐Jörg
Published: August 2010

Several new mono‐ and dinuclear complexes of CoII and NiII with chelating guanidine ligands were synthesized. The molecular structures for most of the complexes in the crystalline state were derived from single‐crystal X‐ray diffraction, and some characteristic structural details are discussed. The molecular magnetism was further studied by superconducting quantum interference device (SQUID) measurements. In addition to the experiments, quantum chemical calculations were carried out. Finally, the paramagnetic NMR spectra for one of the complexes are discussed, which shows that 1JC,H correlation experiments are possible.
Synthesis of AuNi/NiO Nanocables by Porous AAO Template Assisted Galvanic Deposition and Subsequent Oxidation
Authors: Xu Qiaoling , Meng Guowen , Chen Bensong , Li Xiangdong , Zhu Xiaoguang , Chu Zhaoqin , Kong Mingguang
Published: August 2010

A facile and economic approach has been developed for the synthesis of coaxial nanocables with AuNi alloy nanowires as inner solid cores and NiO as outer shells by infiltrating a gold‐coated anodic aluminum oxide (AAO) template, with ring‐shaped Al foil on its outer edge, with a mixed aqueous solution of NiCl2 and HAuCl4 to form AuNi/Ni nanocables, and subsequent immersion in an aqueous NaOH solution to oxidize the Ni sheath during template removal. The formation of the AuNi/Ni nanocables in the channels of the AAO template could be ascribed to the reduction of the Ni2+ ion complexes adhering on the AAO channel walls and the redox reactions of two galvanic cells in which the surrounding Al foil acts as the anode. The approach enables excellent control over the shell thickness and the chemical composition of the AuNi/NiO nanocable by tuning the composition of the mixed solution. The AuNi/NiO nanocables have potentials in nanodevices and nanosystems.
Tuning the Emission Colour of Triphenylamine‐Capped Cyclometallated Platinum(II) Complexes and Their Application in Luminescent Oxygen Sensing and Organic Light‐Emitting Diodes
Authors: Wu Wenting , Cheng Chuanhui , Wu Wanhua , Guo Huimin , Ji Shaomin , Song Peng , Han Keli , Zhao Jianzhang , Zhang Xin , Wu Yubo , Du Guotong
Published: August 2010

[(Aryl‐ppy)Pt(acac)] (ppy = 2‐phenylpyridine, acac = acetylacetonato) derivatives with triphenylamine (TPA) substituents on the ppy ligand have been prepared. The TPA fragment is either directly cyclometallated (Pt‐1) or attached to the ppy ligand through a C–C single bond (Pt‐2) or a novel α‐diketo group (Pt‐3). All the complexes show room‐temperature phosphorescence in fluid solution with emission bands in the range of 530–590 nm, which are red‐shifted relative to the model complex [ppyPt(acac)] (λem = 486 nm). This emission colour tuning effect is attributed to either an elevated HOMO energy caused by electron‐donating TPA substituents on the ppy ligand or a decreased LUMO energy caused by the electron‐trap effect of electron‐withdrawing substituents; both result in a smaller HOMO–LUMO energy gap and thus red‐shifted emission. The complexes show extended luminescence lifetimes (τ = 3.0–5.5 μs) relative to the parent complex [ppyPt(acac)] (τ = 2.6 μs). The luminescent oxygen‐sensing properties of the complexes were studied in solution and polymer films. White light emission was observed with an OLED device fabricated with complex Pt‐3 with CIE coordinates of (0.32, 0.32).
Application of DFT Methods in the Study of VIVO2+–Peptide Interactions
Authors: Micera Giovanni , Garribba Eugenio
Published: August 2010

VIVO2+ complexes formed by histidylglycylglycine (HisGlyGlyH), glycylglycylhistidine (GlyGlyHisH), glycylglycylcysteine (GlyGlyCysH2), N‐glycyl‐bis(imidazol‐2‐yl)methylamine (Gly–BIMA), N‐glycyl‐bis(pyridin‐2‐yl)methylamine (Gly–BPMA), salicylglycyl‐L‐alanine (SalGly‐L‐AlaH2) and 1,2‐bis(2‐hydroxybenzamido)benzene (H2hybeb) in their fully deprotonated form were studied by density functional theory (DFT) methods. They are characterised by different total electric charges, total equatorial charges and number of V–N–amide bonds. DFT calculations enable structural features, like V–donor bond lengths, and spectroscopic features, like electron paramagnetic resonance (EPR) and electronic absorption parameters, to be calculated. The results suggest that an amide group coordinates vanadium in the“amide‐” rather than the “imine‐like” form with the nitrogen atom negatively charged and with a double bond between the carbon and oxygen atoms of the carbonyl group, and that the equatorial charge is delocalised among all the donors bound to vanadium (Ooxido included). The analysis of the molecular orbital composition reveals that the dxy orbital is the vanadium orbital at lower energy, that it can participate in a π bond with the nitrogen pz orbital of the amide groups, that the vanadium dxz and dyz orbitals are involved in a large π interaction with the oxido px and py orbitals and that differences in the donor strengths of the ligands and deviations from the ideal square‐pyramidal symmetry can result in the separation of the energies of the vanadium dxz and dyz orbitals.
Mononuclear Bis(imino)arylcopper(I) N‐Heterocyclic Carbene Complex: Synthesis, Structure, and Reaction with Organic Azide
Authors: An Dongli , Wang Juanjuan , Dong Ting , Yang Ying , Wen Tingbin , Zhu Hongping , Lu Xin , Wang Ye
Published: August 2010

Mononuclear bis(imino)arylcopper(I) N‐heterocyclic carbene compound [(IPM)CuL] {1, L = 2,6‐(RN=CH)2‐4‐tBuC6H2, R = 2,6‐iPr2C6H3, IPM = C[N(iPr)CMe]2} has been synthesized, structurally characterized, and its reaction with 1‐adamantyl azide investigated. The reaction of a less bulky arylcopper(I) compound [(IPM)CuPh] with the azide was also studied. The formation of the corresponding products [(IPM)CuN(1‐ad)NN(L)] (2) and [(IPM)CuN(Ph)NN(1‐ad)] (3) (1‐ad = 1‐adamantyl) reveals an aryl group transfer (L in 2 and Ph in 3) reactivity pattern mediated at CuI with the support of the N‐heterocyclic carbene. However, a Cu–N1‐ad σ‐bond and a Cu···NL weak bond were observed in the structure of 2, significantly different to the bonding in 3 in which a Cu–NPh σ‐bond and a Cu···N1‐ad weak bond were indicated. This may suggest an initial NT (NT, terminal N atom of the azide) coordination of the azide at the Cu center followed by aryl group transfer to NT. Complex 2 may undergo further bond rearrangement of the Cu···N bonds within a pseudo‐CuN3 four‐membered ring as a result of the large bulk of the ligand L.
Synthesis, Structures and Electrochemistry of New Carbonylnickel Octacarbide Clusters: The Distorting Action of Carbide Atoms in the Growth of Ni Cages and the First Example of the Inclusion of a Carbon Atom within a (Distorted) Ni Octahedral Cage
Authors: Bernardi Alessandro , Femoni Cristina , Iapalucci Maria Carmela , Longoni Giuliano , Zacchini Stefano , Fedi Serena , Zanello Piero
Published: August 2010

The reaction of [Ni10C2(CO)15]2– in thf with a large excess of CdCl2·2.5H2O (8–15 equiv.) resulted in the formation of the new carbonyl octacarbide clusters [H5–nNi36C8(CO)36(Cd2Cl3)]n– (n = 3–5), which undergo partial CO replacement to give [Ni36–yC8(CO)34–y(MeCN)3(Cd2Cl3)]3– (y = 0–2) after a prolonged time in MeCN. Treatment of the former with an excess of NaOH afforded the larger [H7–nNi42+yC8(CO)44+y(CdCl)]n– (n = 6, 7; y = 0, 1) octacarbides. Their structures (as well as those of the analogous Br‐containing clusters) have been fully elucidated by single‐crystal X‐ray analysis of their [Me4N]5[Ni36C8(CO)36(Cd2Cl3)]·(7–2y)MeCN·yC6H14 (y = 0.40), [Me4N]3[Ni36–yC8(CO)34–y(MeCN)3(Cd2Cl3)]·5MeCN(y = 0.61), [Me4N]7[Ni42+yC8(CO)44+y(CdCl)]·(5–y)MeCN (y = 0.19) and [Me4N]6[HNi42+yC8(CO)44+y(CdBr)]·(6–y)MeCN (y = 0.19) salts, which feature highly distorted metal cages (due to the inclusion of several carbide atoms), and the presence of partially vacant capping Ni(CO) fragments. This aspect, together with the fact that all these species undergo several protonation–deprotonation equilibria in solution as well as reversible redox processes under electrochemical control, indicates that a detailed description of molecular species containing a few dozen metal atoms might be sometimes rather troublesome and non‐trivial. A complete elucidation of these systems can be achieved only by combining structural, chemical, spectroscopic, electrochemical and spectroelectrochemical studies.
Dimetallic Activation of Dihydrogen Phosphate by Zn(salphen) Chromophores
Authors: Wezenberg Sander J. , Anselmo Daniele , Escudero‐Adán Eduardo C. , Benet‐Buchholz Jordi , Kleij Arjan W.
Published: August 2010

Among a large series of monoanions, dihydrogen phosphate gives an anion‐specific reaction with ZnII–salphen complexes based on a proton transfer to the chromophore. Detailed NMR and UV/Vis spectroscopic studies and mass spectrometric analyses point to initial activation of the phosphate anion upon coordination, followed by protonation of the phenolic positions of a second ZnII–salphen structure as supported by kinetic investigations. For a bis(ZnII–salphen) chromophore this process is accompanied by a considerable colour change.
Structure and Metal‐to‐Insulator Transition of VO2 Nanowires Grown on Sapphire Substrates
Authors: Cheng Yao , Zhang Ting , Cai Yuan , Ho Kin Ming , Fung Kwok Kwong , Wang Ning
Published: August 2010

Single‐crystalline VO2 nanowires exhibit interesting growth phenomena along three equivalent <1$\bar {1}$00> directions of the C‐planes of the sapphire substrates. Under certain growth conditions, VO2 nanowires form V‐shaped twining structures with uniform morphologies and interfaces. Due to the strong elastic stress at the interfaces, the metal‐to‐insulator transition (MIT) of individual VO2 nanowires grown directly on sapphire substrates were observed to display distinct electrical hysteresis loops relative to VO2 nanowires dispersed on sapphire substrates. The distinctive characteristics in the hysteresis loops, exhibited in the process of MIT, are shown to be correlated with the nucleation and growth of periodic/random domain structures in the nanowires during the heating and cooling processes. The periodic domain structures observed in the directly grown nanowires can be explained under the framework of a modified stress‐induced elastic energy model that was first developed for ferroelectric systems.
Ligand‐Controlled Regio‐ and Stereoselective Addition of Carboxylic Acids Onto Terminal Alkynes Catalyzed by Carbonylruthenium(0) Complexes
Authors: Tan Sze Tat , Fan Wai Yip
Published: August 2010

The addition of carboxylic acids onto terminal alkynes was catalyzed by mononuclear ruthenium(0) complexes to give enol esters in high yields. By using ligands with different electronic properties, product selectivity was achieved. E‐enol esters were preferentially produced when tricarbonyl(η4‐diene)ruthenium complexes were used; while geminal enol esters were produced when tricarbonylbis(phosphane)ruthenium complexes were used.
Recent Progress in the Heterogenization of Complexes for Single‐Site Epoxidation Catalysis
Authors: Shylesh Sankaranarayanapillai , Jia Mingjun , Thiel Werner R.
Published: August 2010

Epoxides are of central importance in organic synthesis since they provide access to a series of different 1,2‐difunctionalized intermediates starting from cheap olefins. Olefin epoxidation is catalyzed by a whole bunch of transition metal elements in high oxidation states, the most important are molybdenum, tungsten, rhenium and manganese. Organic peroxides, hydrogen peroxide bleach and even dioxygen have been used as the source of the oxygen atom that is transferred to the olefin. The present microreview summarizes the recent developments in terms of catalyst heterogenization for olefin epoxidation. Such strategies are requested for green synthesis protocols and are of special interest for expensive catalysts derived, e. g. from rhenium or complex chiral ligands.
The First Observation of theE,ZConfiguration Of Ar–X–N=S=N–X–Ar (X = S, Se) Chains in the Crystalline State
Authors: Makarov Arkady G. , Bagryanskaya Irina Yu. , Gatilov Yuri V. , Kuratieva Natalia V. , Makarov Alexander Yu. , Shakirov Makhmut M. , Alexeyev Alexey V. , Tersago Karla , Van Alsenoy Christian , Blockhuys Frank , Zibarev Andrey V.
Published: August 2010

New oligomeric analogues of poly(sulfur nitride), i.e. 3‐ClC6R4–X–N=S=N–X–C6R4Cl‐3 (5–8; R = H, F and X = S, Se), were synthesized and structurally characterized in the solid state by single‐crystal XRD, in solution by variable‐temperature NMR spectroscopy and in the gas phase with DFT/B3LYP calculations. In the crystal, compounds5–7display the well‐knownZ,Zconfiguration, whereas8(R = F, X = Se) is the first compound to display theE,Zconfiguration amongst twelve structurally defined Ar–X–N=S=N–X–Ar (X = S, Se) derivatives in the hydrocarbon and fluorocarbon series. Through a careful analysis of the packing schemes and the intermolecular interactions of the various compounds, an explanation of the abnormal behaviour of8is put forward.
A Novel One‐Step Approach to Synthesize Fluorescent Carbon Nanoparticles
Authors: Zhang Bing , Liu Chun‐yan , Liu Yun
Published: August 2010

Fluorescent carbon nanoparticles (CNPs) were prepared directly by a simple hydrothermal method by using L‐ascorbic acid as a carbon source. The synthesized CNPs with higher photoluminescence efficiencies (6.79 %) are monodisperse, and their diameter is about 2.0 nm. In contrast to previous methods, for this one‐step process, neither strong acid treatment nor further surface modification is necessary. Aqueous solutions of the CNPs are stable at room temperature for at least half a year. In particular, the fluorescence of the CNPs does not change over a wide pH range and even in solvents with strong ionic strengths (e.g. 2 M NaCl).
The Doubly Base‐Stabilized Diborane(4) [HB(μ‐hpp)]2 (hpp = 1,3,4,6,7,8‐hexahydro‐2H‐pyrimido[1,2‐a]pyrimidinate): Synthesis by Catalytic Dehydrogenation and Reactions with S8 and Disulfides
Authors: Schulenberg Nikola , Ciobanu Oxana , Kaifer Elisabeth , Wadepohl Hubert , Himmel Hans‐Jörg
Published: August 2010

In this work we report on new experiments on the catalytic dehydrogenation of [H2B(μ‐hpp)]2 leading to the doubly base‐stabilized diborane(4) [HB(μ‐hpp)]2 featuring two hpp bridges (hpp = 1,3,4,6,7,8‐hexahydro‐2H‐pyrimido[1,2‐a]pyrimidinate) under mild conditions. Several dehydrogenation (pre)catalysts were tested. The best one turned out to be Ru3(CO)12, allowing quantitative dehydrogenation already at 60 °C. Subsequently we subjected [HB(μ‐hpp)]2 to reactions with S8 and disulfides (Ph2S2 and Bn2S2, Bn = benzyl). Reaction with S8 leads to oxidative insertion of one sulfur atom into the B–B bond and formation of [HB(μ‐hpp)]2(μ‐S). In the case of disulfides, substitution reactions leading to the doubly base‐stabilized diborane(4) species [RSB(μ‐hpp)]2 and HB(μ‐hpp)2BSR (R = Ph or Bn) compete with sulfuration again leading to [HB(μ‐hpp)]2(μ‐S).
Acetylacetonato(phosphane)iridium Complexes: Synthesis and Catalytic Activity in the Cyclization of Alkynoic Acids
Authors: Geier Michael J. , Vogels Christopher M. , Decken Andreas , Westcott Stephen A.
Published: August 2010

The iridium complex [Ir(acac)(η2‐coe)2] (1) has been easily prepared by the addition of Tl(acac) to a suspension of [Ir(μ‐Cl)(η2‐coe)2]2 in hexane. Complex 1 has been characterized fully including an X‐ray diffraction study. It is moderately stable and is a useful precursor to a number of different acetylacetonato(phosphane)iridium complexes via addition of monodentate and bidentate phosphanes. Reactions proceeded at room temperature to give high yields of the desired square planar phosphane complexes [Ir(acac)(P)] (2: P = 2 PPh3, 3: P = 2 PMePh2, 4: P = dppm, 5: P = dppe, 6: P = dppp, 7: P = dppb, 8: P = dppf, 9: P = dcpe) except for those involving dppe, which gave a complicated mixture of products. Complex [Ir(acac)(dppe)] (5) was prepared in a microwave reactor at 125 °C. All complexes prepared in this study were efficient in the intramolecular catalyzed cyclization of4‐pentynoic acid to give exclusive formation of the exocyclic γ‐methylene‐γ‐butyrolactone. Complex 1 was found to be the most active and selective catalyst precursor for the intramolecular cyclization of both 4‐pentynoic acid and 5‐hexynoic acid.
Synthesis and Characterization of Colloidal Core–Shell Semiconductor Nanowires
Authors: Li Zhen , Ma Xuedan , Sun Qiao , Wang Zhe , Liu Jian , Zhu Zhonghua , Qiao Shi Zhang , Smith Sean C. , Lu Gaoqing (Max) , Mews Alf
Published: August 2010

CdSe colloidal nanowires, generated from solution‐liquid‐solid approach, have been coated with CdS rods (or ribbons) by using cadmium hexadecyl xanthate (Cd‐HDX) as a single source precursor. The use of different solvents and ligands causes pronounced effects on the morphology of the nanowires. The coating process includes nucleation and growth of CdS nanorods onto the core CdSe nanowires, followed by ripening of the CdS nanorods to produce the desired core‐shell nanowire structure.
Stabilizing flaxseed oil with individual antioxidants and their mixtures
Authors: Omar Khamis Ali , Shan Liang , Wang Yan Ling , Wang Xingguo
Published: August 2010

In vitro reducing power tests of tea polyphenols (Tp), tert‐butylhydroquinone (TBHQ), and monoglyceride citrate (MGC) revealed that, at certain concentrations, Tp + TBHQ displayed a strong reductive capacity. Moreover, 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical‐scavenging activity tests showed that Tp + TBHQ was effective (p < 0.05) in quenching DPPH radicals. The effectiveness of Tp + TBHQ towards the radical‐scavenging activity was also found to be increased when their concentrations were increased. The oxidation stability of flaxseed oil (FO) was investigated as a function of time at high temperature, in the absence and presence of antioxidants; the peroxide value (PV) and p‐anisidine value of FO were determined as indicators of oxidation at 60°C during 20 days. The results revealed that Tp200 + TBHQ100 (subscripts refer to amounts in mg/kg) had noticeable reduction effects on the oxidation (PV and p‐anisidine) of FO compared with TBHQ200 regarding the PV, and when compared with the mixture of TBHQ100 + MGC100 regarding the p‐anisidine value. However, according to Rancimat tests, the ternary mixture (Tp200 + TBHQ100 + MGC100) was found to be more effective in controlling FO oxidation. The induction periods for FO containing Tp200 + TBHQ100 + MGC100, TBHQ100 + MGC100, and Tp200 + TBHQ100 were 8.305, 6.905, and 6.8020 h, respectively, whereby no significant differences were observed between TBHQ100 + MGC100 and Tp200 + TBHQ100 (p < 0.025).

Practical applications: Flaxseed oil is an unstable vegetable oil due to its high content of PUFA, which are mainly composed of α‐linolenic acid (ALA). One effective way to ensure a high quality of lipids and lipid‐containing products, and to prolong their storage time, is to stabilize them by addition of suitable antioxidants. The stabilization of FO will help to increase both its shelf life and to improve its use in different applications. According to recent studies, FO contains many components that are beneficial for human health, especially ALA which can contribute to increasing the DHA and EPA content in the body. FO is believed to provide benefits in the prevention and treatment of heart diseases, arthritis, inflammatory, and autoimmune diseases.
Vinylogous Mukaiyama–Michael Reactions between 2‐Silyloxyfurans and Cyclic Enones or Unsaturated Oxo Esters
Authors: Chabaud Laurent , Jousseaume Thierry , Retailleau Pascal , Guillou Catherine
Published: August 2010

Lewis acid catalyzed vinylogous Mukaiyama–Michael (VMM) reactions between 2‐(trialkylsilyloxy)furans 1 and α,β‐unsaturated cyclic enones 2 or oxo esters 4 have been investigated. Both substrates proved to be useful Michael acceptors in the title reaction, giving the butenolides 3 and 5 in good yields. A comparative study between the α,β‐unsaturated cyclic enones 2 and the oxo esters 4 as Michael acceptors showed better diasterecontrol with the latter class of compounds. In both series, crystal structures of the major isomers revealed anti relationships of newly formed stereogenic centers. From these data, two types of transition states could be proposed: an open TS with antiperiplanar orientation or a Diels–Alder‐like TS with exo approach.
Synthesis and Reactivity of 3‐Alkynyldihydroselenophene Derivatives
Authors: Rosário Alisson R. , Schumacher Ricardo F. , Gay Bibiana M. , Menezes Paulo H. , Zeni Gilson
Published: August 2010

We present herein our results on the synthesis of 3‐alkynyldihydroselenophenes by palladium‐catalyzed Sonogashira cross‐coupling of 3‐iododihydroselenophenes with different alkynes under mild conditions in good to excellent yields. The developed protocol tolerated a wide range of functional groups in the dihydroselenophenes and alkynes. These 3‐alkynyldihydroselenophenes, bearing the chalcogen group, underwent highly selective intramolecular cyclizations when treated with I2to afford fused dihydroselenophene[2,3,b]selenophene rings. In addition, 3‐alkynyldihydroselenophene obtained by this methodology was also submitted to an oxidative reaction by using DDQ to give the aromatic selenophene in moderated yields.
Application of Selective Palladium‐Mediated Functionalization of the Pyrido[3′,2′:4,5]pyrrolo[1,2‐c]pyrimidine Heterocyclic System for the Total Synthesis of Variolin B and Deoxyvariolin B
Authors: Baeza Alejandro , Mendiola Javier , Burgos Carolina , Alvarez‐Builla Julio , Vaquero Juan J.
Published: August 2010

The reaction of protected 3‐bromo‐2‐(bromomethyl)‐4‐methoxypyrrolo[2,3‐b]pyridine and tosylmethyl isocyanide (TosMIC) afforded a pyrido[3′,2′:4,5]pyrrolo[1,2‐c]pyrimidine derivative in good yield. This compound was transformed through installation of the pyrimidine moiety in the C5 position, hydrolysis, and decarboxylation in an advanced intermediate for the total or formal synthesis of the naturalalkaloid variolin B. Reaction of 3‐bromo‐2‐(bromomethyl)‐4‐chloropyrrolo[2,3‐b]pyridine with N‐tosylmethyl dichloroformimide as a synthetic TosMIC equivalent afforded trihalo‐substituted pyrido[3′,2′:4,5]pyrrolo[1,2‐c]pyrimidine. This compound was used in a new total synthesis of the alkaloid variolin B by selective and sequential C–N, C–C, and C–O palladium‐mediated functionalization at the C9, C5, and C4 positions of the pyrido[3′,2′:4,5]pyrrolo[1,2‐c]pyrimidine system. A formal synthesis of deoxyvariolin B is also described by using the same synthetic strategy.
1‐exo‐Alkylidene‐2,3‐anhydrofuranoses: Valuable Synthons in the Preparation of Furanose‐Based Templates
Authors: Gómez Ana M. , Pedregosa Ana , Uriel Clara , Valverde Serafín , López J. Cristóbal
Published: August 2010

Highly functionalized 1‐exo‐alkylidene‐2,3‐anhydro‐, and 1′‐halo‐1‐exo‐alkylidene‐2,3‐anhydrofuranoses can be prepared in four or five steps, respectively, from D‐mannose. These compounds feature a variety of functionalities, including a double bond, an oxirane, an allylic oxirane and (in the case of the 1′‐halo derivative) an alkenyl halide. The reactivity of each functionality in these derivatives has been explored, and the usefulness of these substrates has been demonstrated with the preparation of furanose‐based carbohydrate templates with up to four sites of molecular diversity.
Synthesis, Biological Evaluation and Docking Studies of Casuarine Analogues: Effects of Structural Modifications at Ring B on Inhibitory Activity Towards Glucoamylase
Authors: Bonaccini Claudia , Chioccioli Matteo , Parmeggiani Camilla , Cardona Francesca , Lo Re Daniele , Soldaini Gianluca , Vogel Pierre , Bello Claudia , Goti Andrea , Gratteri Paola
Published: August 2010

We report the total synthesis of a series of pyrrolizidine analogues of casuarine (1) and their 6‐O‐α‐glucoside derivatives. The synthetic strategy is based on a totally regio‐ and stereoselective 1,3‐dipolar cycloaddition of suitably substitutedalkenes and a carbohydrate‐based nitrone. We also report the evaluation of the biological activity of casuarine and its derivatives towards a wide range of glycosidases and a molecular modeling study focused on glucoamylase (GA) in which the binding modes of the newly synthesized compounds within the enzyme cavity are investigated. The results highlight the prominent structural features of casuarine and its derivatives that make them selective glucoamylase inhibitors.
PhI(OAc)2/KI‐Mediated Reaction of Aryl Sulfinates with Alkenes, Alkynes, and α,β‐Unsaturated Carbonyl Compounds: Synthesis of Vinyl Sulfones and β‐Iodovinyl Sulfones
Authors: Katrun Praewpan , Chiampanichayakul Supanimit , Korworapan Kanokwan , Pohmakotr Manat , Reutrakul Vichai , Jaipetch Thaworn , Kuhakarn Chutima
Published: August 2010

(Diacetoxyiodo)benzene [PhI(OAc)2, DIB] was able to promote the reaction of sodium aryl sulfinate and potassiumiodide (KI) with alkenes and alkynes to afford the corresponding vinyl sulfones and β‐iodovinyl sulfones, respectively, in good yields. The salient features of this reaction are that it employs a commercially available and environmentally benign hypervalent iodine(III) reagent, a one‐step reaction, a short reaction time, and mild reaction conditions.
Highly Efficient and Practical Pyrrolidine–Camphor‐Derived Organocatalysts for the Direct α‐Amination of Aldehydes
Authors: Liu Pang‐Min , Magar Dhananjay R. , Chen Kwunmin
Published: August 2010

A series of pyrrolidine–camphor‐derived organocatalysts (1–4) were designed and synthesised. These organocatalysts were used for direct α‐amination of aldehydes with dialkyl azodicarboxylates to give the desired α‐aminated products in high chemical yields (up to 92 %) and with high to excellent levels of stereoselectivity (up to >99 % ee). The reactions proceeded rapidly (within 5 min) with low catalyst loading (5 mol‐%) at ambient temperature. Enantioselective aminations of asymmetric α,α‐disubstituted aldehydes in the catalytic system were studied, with reasonable to high stereoselectivities (up to 75 % ee) being obtained. The utility of this methodology was demonstrated with the synthesis of derivatives of β‐amino‐γ‐butyrolactone and a tetrasubstitutedcyclohexane‐derived amino alcohol with high stereoselectivities. Transition models were proposed for the asymmetric α‐amination reactions; they involve hydrogen‐bond interactions between the nucleophilic enamine formed in situ and the nitrogen source.
Novel Dithienylethenes with Extended π‐Systems: Synthesis by Aldol Condensation and Photochromic Properties
Authors: Altenhöner Kai , Lamm Jan‐Hendrik , Mattay Jochen
Published: August 2010

A facile and stereoselective route to symmetric π‐extended dithienylethene derivatives is described. The key step of this route is an aldol condensation of 1,2‐bis(5‐formyl‐2‐methylthiophen‐3‐yl)cyclopentene with a large variety of acyl compounds. All synthesized photoswitches can be reversibly converted into the closed form by irradiation with visible light. The photochromic properties of nine new dithienylethenes are discussed.