bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel polymorphic purine complex at the 1.5 kb upstream region of the human caveolin‐1 gene and risk of Alzheimer's disease; Extra‐short alleles and accumulated allele homozygosity
Authors: Heshmati Y. , Mirabzadeh A. , Feizzade G. , Gilanipour M. , Etminan M.R. , Khoram Khorshid H.R. , Kamali K. , Fakhri M. , Moghimi N. , Najmabadi H. , Ohadi M.
Published: February 2009

Crucial interaction of caveolin‐1 (CAV1) with β‐ and γ‐secretases, and aberrant expression of the gene encoding this protein in Alzheimer's disease (AD) support a role for CAV1 in the pathophysiology of this disease. We report a novel polymorphic purine complex stretching ∼150 bp of genomic DNA at the 1.5 kb upstream region of the human CAV1 gene, alleles and genotypes of which are associated with sporadic late‐onset AD. Extra‐short alleles were observed in the case group that were absent in the control subjects. Remarkably, 63% of these alleles were observed to be homozygous in length, forming 23.7% of the homozygote length compartment in the AD cases (χ2 = 19.08, df = 1, P < 0.000007). Increased homozygosity for length was also observed at this region in the Alzheimer's cases, for the allele lengths shared by the case and control groups [(χ2 = 30.75, df = 1, P < 0.0000000, OR = 4.54, CI 95% (2.56–8.3)]. This region contains GGAA and GAAA motifs, the consensus binding sites for the Ets and IRF family transcription factors, respectively, and is highly conserved in distantly related non‐human primates in respect with location and motif sequence. The effect of this complex sequence on the expression of CAV1, and the related mechanisms in the pathophysiology of AD remain to be clarified. © 2008 Wiley‐Liss, Inc.
How Neandertals inform human variation
Authors: Wolpoff Milford H.
Published: February 2009

Since their first discovery, Neandertals have served as an out‐group for interpreting human variation. Their out‐group role has changed over the years because in spite of the fact that Neandertals are the most abundant of all fossil remains (or perhaps because of this) their interpretation is the most controversial of all human fossils. Many believe them to be a different, albeit human‐like species, but recent genetic evidence supports anatomical interpretations indicating that interbreeding with other humans was an important aspect of human evolution. The combination of anatomical difference and restricted gene flow between populations suggests the possibility that Neandertals may have been a true human race. Am J Phys Anthropol 2009. © 2009 Wiley‐Liss, Inc.
Beyond Reppe: Building Substituted Arenes by [2+2+2] Cycloadditions of Alkynes
Authors: Galan Brandon R. , Rovis Tomislav
Published: February 2009

Synthetic sequel: The transition‐metal‐catalyzed [2+2+2] cycloaddition is an established method for the construction of carbocyclic frameworks but is often plagued by poor selectivity. Recent literature paints a promising picture—a more general metal‐catalyzed [2+2+2] cycloaddition can be accomplished intermolecularly using three separate alkynes to furnish highly substituted arenas (see scheme).

magnified image
A Method for the Positioning and Tracking of Small Moving Particles
Authors: Rees Neil V. , Matthews Sinéad M. , Yunus Kamran , Fisher Adrian C. , Compton Richard G.
Published: February 2009

On the move: Electrochemistry has been used to detect and monitor the motion of a single 330 μm sphere in both time and space (see picture). The motion was recorded simultaneously by video and chronoamperometry, which showed an excellent correlation. The ability to fabricate electrode arrays capable of spatial resolution at the sub‐micrometer scale opens the possibility of using this technique to monitor considerably smaller particles.

magnified image
Epimerization‐Free Block Synthesis of Peptides from Thioacids and Amines with the Sanger and Mukaiyama Reagents
Authors: Crich David , Sharma Indrajeet
Published: February 2009

Highly activated thioesters formed by the rapid reaction of C‐terminal thioacids derived from protected amino acids and peptides with the Sanger reagent and other electron‐deficient aryl halides in the presence of a free amine immediately form a peptide bond with the amine. This essentially epimerization‐free method was used for the 4+4 block synthesis of a hindered octapeptide (see scheme; Boc, Pbf, and Trt are protecting groups).

magnified image
Fluorescent Color Readout of DNA Hybridization with Thiazole Orange as an Artificial DNA Base
Authors: Berndl Sina , Wagenknecht Hans‐Achim
Published: February 2009

A fluorescent chameleon: A single thiazole orange (TO) dye, when used as an artificial DNA base shows the typical green emission, whereas the interstrand TO dimer exhibits an orange excimer‐type emission inside duplex DNA (see picture).

magnified image
The effect of carbon nanotube on the physical properties of poly(butylene terephthalate) nanocomposite by simple melt blending
Authors: Kim Jun Young
Published: February 2009

Polyester nanocomposites based on poly(butylene terephthalate) (PBT) and carbon nanotube (CNT) were prepared by simple melt blending using a twin‐screw extruder. There is significant dependence of the thermal, rheological, and mechanical properties of the PBT nanocomposites on the concentration and dispersion state of CNT. The storage and loss moduli of the PBT nanocomposites increased with increasing frequency, and this enhancing effect was more pronounced at lower frequency region. The nonterminal behavior for the PBT nanocomposites was attributed to the nanotube–nanotube or polymer–nanotube interactions, and the dominant nanotube–nanotube interactions at high CNT content resulted in the formation of the interconnected network‐like structures of CNT in the PBT nanocomposites. The incorporation of a small quantity of CNT into the PBT matrix can substantially improve the mechanical properties, the heat distortion temperature, and the thermal stability of the PBT nanocomposites. The unique character of CNT dispersed in the PBT matrix resulted in the physical barrier effect against the thermal decomposition, leading to the improvement in the thermal stability of the PBT nanocomposites. This study also provides a design guide of CNT‐reinforced PBT nanocomposites with a great potential for industrial uses. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
A new adaptive backstepping Coulomb friction compensator for servo control systems
Authors: Yu Jen‐te
Published: February 2009

A new Coulomb friction compensator is proposed for servo control systems in this paper. The novelty of the new approach lies in its capability of assigning the eigenvalues of the resulting closed loop system while attacking the problem. First, based on the standard backstepping methodology, an implicit Lyapunov function, with part of the components being only symbolically constructed at the very beginning, is utilized. To increase the robustness of the system against disturbance and model inaccuracy, an integral term is employed in the design. Using part of the variable gradient method, we are able to turn the implicit Lyapunov function into an explicit one, which is positive definite, and whose time‐derivative is negative definite. Second, it will be shown that the resulting closed loop error system is a switched linear system with two possible active modes that share the same set of eigenvalues, which is at our disposal. Unlike the common adaptive control design methods, such as the Control Lyapunov Function approach, in which the gains are typically positive but otherwise arbitrary, and are hence difficult to choose and have a lack of connection with the system's performance, our new scheme imposes two further constraints on the gains. It turns out that we can then match these gains with the coefficients of the desired characteristic equation of the closed loop system. In this respect, the gains are linked to the system's overall performance, which is a new and very appealing feature for such a scheme. Finally, a procedure of constructing a common Lyapunov function is provided to prove exponential stability of the aforementioned switched linear system. In addition, using the invariance principle, we will show the convergence of the estimated Coulomb friction coefficient to its real value. Numerical simulations are given to validate the effectiveness of the design and its robustness against friction time‐variations. Compared to existing results, the proposed scheme is much simpler, hence, much more advantageous computationally. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Energy absorption capacity; a new concept for stability analysis of nonlinear dynamic systems
Authors: Jamshidifar Ali Akbar , Afshar Ahmad
Published: February 2009

Stability is the main concern considered for every system. Generally the well‐known Lyapunov and input‐output stability methods are utilized for the stability analysis of nonlinear systems. These methods face serious difficulties as the size and complexity of the systems increases. In this paper a new approach is presented to overcome this problem by introducing a new concept “Energy Absorption Capacity” (EAC) for every component. The EAC of the system can be derived from its component EACs considering their interaction. It is shown that the stability of every individual component is assured if its EAC has a positive value. The proposed approach is less conservative compared to a Lyapunov‐based approach. This is due to its reliance on EAC as the extreme value of energy function rather than the function itself. Some examples are given to support the proposed approach. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
State feedback control synthesis for networked control systems with packet dropout
Authors: Wang Yu‐Long , Yang Guang‐Hong
Published: February 2009

This paper is concerned with the problem ofH∞controller design for networked control systems (NCSs) with time delay and packet dropout. A combined switching and parameter uncertainty‐based method is proposed to deal with time‐varying delay. The proposed method can avoid the high computational complexity of the delay switching‐based method and introduce less conservatism than the parameter uncertainty‐based method. An active varying sampling period method is proposed to make full use of network bandwidth, and a multi‐objective optimization methodology in terms of linear matrix inequalities is used to deal withH∞controller design for NCSs with active varying sampling period. The simulation results illustrate the effectiveness of the proposed active varying sampling period method and the less conservatism of the combined switching and parameter uncertainty‐based method. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
A matrix gradient algorithm for identification of parameterized time‐varying parameters
Authors: Chen Min‐Shin , Li Jyun‐Sian , Wu Po‐Ching
Published: February 2009

This paper considers the problem of estimating time‐varying parameters which can be parameterized by a series of arbitrary known basis functions. It is shown that this problem is equivalent to the observer design problem for a “matrix” dynamic system. A “matrix” gradient algorithm, which mimics the well‐known “vector” gradient algorithm, is proposed to estimate the unknown matrix. The contribution of this paper is to show that convergence of the proposed matrix algorithm is guaranteed by the persistent excitations of both the regressor and the basis functions. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
H∞ fuzzy static output feedback control of T‐S fuzzy systems based on fuzzy Lyapunov approach
Authors: Chang Xiao‐Heng , Yang Guang‐Hong , Liu Xiao‐Ping
Published: February 2009

This paper is concerned with the problem of H∞ fuzzy static output feedback control for discrete‐time Takagi‐Sugeno (T‐S) fuzzy systems, and new design methods are presented. By defining a fuzzy Lyapunov function, a new sufficient condition guaranteeing the H∞ performance of the T‐S fuzzy systems is derived, and the condition is expressed by a set of linear matrix inequalities. In comparison with the existing literature, the proposed approach may provide more relaxed condition while ensuring better H∞ performance. The simulation results illustrate the effectiveness of the proposed approach. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Network‐based robust control of stochastic systems with nonlinear perturbations
Authors: Zhang Xiaomei , Zheng Yufan , Lu Guoping
Published: February 2009

Network‐based robust control of stochastic systems with nonlinear perturbations is investigated in this paper. State and static output feedback controllers are designed, respectively, for stochastic networked control systems subject to the presence of network‐induced delay, transmitted data dropout and nonlinear perturbations. Using the Lyapunov‐Krasovskii functional and descriptor system approach, a state feedback controller and a static output feedback controller are constructed in terms of linear matrix inequalities, respectively. With the controllers, the corresponding closed‐loop systems are stochastically ultimately bounded in the mean square. Two examples are provided to demonstrate the effectiveness of the proposed methods. Copyright © 2009 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Bayesian estimation of finite time ruin probabilities
Authors: Ausin M. Concepcion , Wiper Michael P. , Lillo Rosa E.
Published: February 2009

In this paper, we consider Bayesian inference and estimation of finite time ruin probabilities for the Sparre Andersen risk model. The dense family of Coxian distributions is considered for the approximation of both the inter‐claim time and claim size distributions. We illustrate that the Coxian model can be well fitted to real, long‐tailed claims data and that this compares well with the generalized Pareto model. The main advantage of using the Coxian model for inter‐claim times and claim sizes is that it is possible to compute finite time ruin probabilities making use of recent results from queueing theory. In practice, finite time ruin probabilities are much more useful than infinite time ruin probabilities as insurance companies are usually interested in predictions for short periods of future time and not just in the limit. We show how to obtain predictive distributions of these finite time ruin probabilities, which are more informative than simple point estimations and take account of model and parameter uncertainty. We illustrate the procedure with simulated data and the well‐known Danish fire loss data set. Copyright © 2009 John Wiley & Sons, Ltd.
Biliary clearance of bromosulfophthalein in anesthetized and freely moving conscious rat
Authors: Oh Ju‐Hee , Park Se‐Eun , Shim Chang‐Koo , Lee Young‐Joo
Published: February 2009

The aim of this study was to investigate the effect of anesthesia on the pharmacokinetics of bromosulfophthalein (BSP) with focus on biliary clearance. The plasma concentration profile and biliary clearance of intravenously administered BSP was compared in conscious freely moving bile duct catheterized rats and rats anesthetized with ketamine or Zoletil. The plasma concentration of BSP in conscious rats was similar to that of anesthetized rats, irrespective of the anesthetic used. There was no significant difference in the volume of distribution, total body clearance and mean residence time of BSP between the groups. The biliary clearance of BSP in rats anesthetized using ketamine or Zoletil was also similar to that of conscious rats. Only bile flow was increased under anesthetization compared with conscious rats. These results demonstrate that the pharmacokinetics of BSP, including biliary clearance, in ketamine or Zoletil anesthetized rats is virtually identical to that in conscious rats and it may be related to blood flow limited hepatic disposition of BSP. Furthermore, they suggest the conscious rat model does not offer methodological advantage and the anesthesia model is suitable for a realistic approximation of the hepatobiliary transport of BSP. Copyright © 2009 John Wiley & Sons, Ltd.
Investigation of some factors contributing to negative food effects
Authors: Marasanapalle Venugopal P. , Crison John R. , Ma Jingwen , Li Xiaoling , Jasti Bhaskara R.
Published: February 2009

A drug is defined as exhibiting negative food effects, if the co‐administration of food statistically decreases its area under the curve, AUC, when compared with its administration on a fasted stomach. In this study, the role of biopharmaceutical factors that contribute to negative food effects was studied using furosemide, nadolol, tacrine and atenolol (as model compounds exhibiting negative food effects), and prednisolone, hydrochlorothiazide and ibuprofen (as model compounds that do not show any food effects). The physiological pH of the upper intestinal tract is lower, at pH 5, in the postprandial state when compared with the preprandial state, pH 6.5. Drugs that exhibited negative food effects had low apical to basolateral Caco‐2 permeabilities, low pKa/pKb and Log P values of less than 1. The drugs exhibiting negative food effects had low distribution coefficients at the pH conditions of the fed and fasted states. Furosemide, being a hydrophilic, poorly soluble acidic drug showed lower solubility in the fed state when compared with the fasted state. Basic drugs, atenolol, nadolol and tacrine, are ionized to a higher extent in the fed state and exhibit lower permeability and lower absorption when compared with the fasted state. Thus, drugs were found to exhibit negative food effects owing to their decrease in solubility or permeability in the upper intestinal tract of the fed state when compared with the fasted state. Copyright © 2009 John Wiley & Sons, Ltd.
Establishing stimulus control of vocal stereotypy displayed by young children with Autism
Authors: Rapp John T. , Patel Meeta R. , Ghezzi Patrick M. , O'Flaherty Christine H. , Titterington Craig J.
Published: February 2009

We examined the vocal stereotypy of three boys who were diagnosed with an Autism Spectrum Disorder (ASD). Results of functional analyses indicated that each participant's vocal stereotypy was maintained by non‐social consequences. For two participants, verbal reprimands were provided contingent on vocal stereotypy in the presence of a red card (RC). For the third participant, after verbal reprimands alone did not decrease vocal stereotypy, toys were withdrawn contingent on vocal stereotypy in the presence of the RC. For all three participants, vocal stereotypy was permitted without programmed consequences the presence of a green card (GC). The results showed that vocal stereotypy decreased in the presence of the RC for all three participants; however, vocal stereotypy came under inhibitory control of the RC for only one of the three participants. The potential utility of using punishment to develop stimulus control of automatically reinforced problem behavior in academic settings is briefly discussed. Copyright © 2009 John Wiley & Sons, Ltd.
Gastrin‐releasing peptide: Different forms, different functions
Authors: Ischia Joseph , Patel Oneel , Shulkes Arthur , Baldwin Graham S.
Published: February 2009

All forms of the neuropeptide gastrin‐releasing peptide (GRP) are derived from the precursor proGRP1‐125. Amidated GRP18‐27, which together with amidated GRP1‐27 was long thought to be the only biologically relevant product of the GRP gene, is involved in a multitude of physiological functions and acts as a mitogen, morphogen, and proangiogenic factor in certain cancers. Recently, GRP has been implicated in several psychiatric conditions, in the maintenance of circadian rhythm, in spinal transmission of the itch sensation, and in inflammation and wound repair. The actions of GRP are mediated by the GRP receptor. Over the last decade, nonamidated peptides derived from proGRP, such as the glycine‐extended form GRP18‐28 and recombinant and synthetic fragments from proGRP31‐125, have been shown to be biologically active in a range of tissues and in cancer cell lines. While GRP18‐28 acts via the GRP receptor, the identity of the receptor for proGRP31‐125 and its fragments has not yet been established. Nonamidated fragments are also present in normal tissues and in various cancers. In fact, proGRP31‐98 is the most sensitive serum biomarker in patients with small cell lung cancer and is a significant predictor of poor survival in patients with advanced prostate cancer. © 2009 International Union of Biochemistry and Molecular Biology, Inc.
Conjugated linoleic acid isomers: Differences in metabolism and biological effects
Authors: Churruca Itziar , Fernández‐Quintela Alfredo , Portillo Maria Puy
Published: February 2009

The term conjugated linoleic acid (CLA) refers to a mixture of linoleic acid positional and geometric isomers, characterized by having conjugated double bonds, not separated by a methylene group as in linoleic acid. CLA isomers appear as a minor component of the lipid fraction, found mainly in meat and dairy products from cows and sheep. The most abundant isomer is cis‐9,trans‐11, which represents up to 80% of total CLA in food. These isomers are metabolized in the body through different metabolic pathways, but important differences, that can have physiological consequences, are observed between the two main isomers. The trans‐10,cis‐12 isomer is more efficiently oxidized than the cis‐9,trans‐11 isomer, due to the position of its double bounds. Interest in CLA arose in its anticarcinogenic action but there is an increasing amount of specific scientific literature concerning the biological effects and properties of CLA. Numerous biological effects of CLA are due to the separate action of the most studied isomers, cis‐9,trans‐11 and trans‐10,cis‐12. It is also likely that some effects are induced and/or enhanced by these isomers acting synergistically. Although the cis‐9,trans‐11 isomer is mainly responsible for the anticarcinogenic effect, the trans‐10,cis‐12 isomer reduces body fat and it is referred as the most effective isomer affecting blood lipids. As far as insulin function is concerned, both isomers seem to be responsible for insulin resistance in humans. Finally, with regard to the immune system it is not clear whether individual isomers of CLA could act similarly or differently. © 2009 International Union of Biochemistry and Molecular Biology, Inc.
Insulin‐like growth factor‐I receptor signal transduction and the Janus Kinase/Signal Transducer and Activator of Transcription (JAK‐STAT) pathway
Authors: Himpe Eddy , Kooijman Ron
Published: February 2009

The insulin‐like growth factor IGF‐I is an important fetal and postnatal growth factor, which is also involved in tissue homeostasis via regulation of proliferation, differentiation, and cell survival. To understand the role of IGF‐I in the pathophysiology of a variety of disorders, including growth disorders, cancer, and neurodegenerative diseases, a detailed knowledge of IGF‐I signal transduction is required. This knowledge may also contribute to the development of new therapies directed at the IGF‐I receptor or other signaling molecules. In this review, we will address IGF‐I receptor signaling through the JAK/STAT pathway in IGF‐I signaling and the role of cytokine‐induced inhibitors of signaling (CIS) and suppressors of cytokine signaling (SOCS). It appears that, in addition to the canonical IGF‐I signaling pathways through extracellular‐regulated kinase (ERK) and phosphatidylinositol‐3 kinase (PI3K)‐Akt, IGF‐I also signals through the JAK/STAT pathway. Activation of this pathway may lead to induction of SOCS molecules, well‐known feedback inhibitors of the JAK/STAT pathway, which also suppress of IGF‐I‐induced JAK/STAT signaling. Furthermore, other IGF‐I‐induced signaling pathways may also be modulated by SOCS. It is conceivable that the effect of these classical inhibitors of cytokine signaling directly affect IGF‐I receptor signaling, because they are able to associate to the intracellular part of the IGF‐I receptor. These observations indicate that CIS and SOCS molecules are key to cross‐talk between IGF‐I receptor signaling and signaling through receptors belonging to the hematopoietic/cytokine receptor superfamily. Theoretically, dysregulation of CIS or SOCS may affect IGF‐I‐mediated effects on body growth, cell differentiation, proliferation, and cell survival. © 2009 International Union of Biochemistry and Molecular Biology, Inc.
Sarcopenia of aging: Underlying cellular mechanisms and protection by calorie restriction
Authors: Marzetti Emanuele , Anne Lees Hazel , Eva Wohlgemuth Stephanie , Leeuwenburgh Christiaan
Published: February 2009

Sarcopenia, the loss of muscle mass and function, is a common feature of aging and impacts on individual health and quality of life. Several cellular mechanisms have been involved in the pathogenesis of this syndrome, including mitochondrial dysfunction, altered apoptotic and autophagic signaling, and, more recently, trace metal dyshomeostasis. Calorie restriction (CR) without malnutrition has been shown to ameliorate the age‐related loss of muscle mass in a variety a species. Mechanisms of protection span from preservation of mitochondrial functional and structural integrity to mitochondrial biogenesis, reduction of oxidative stress, and favorable modulation of apoptotic and autophagic signaling pathways. Importantly, preliminary evidence indicates that moderate CR may promote muscle mitochondrial biogenesis in middle‐aged human subjects. Further research is warranted to investigate whether CR may represent a safe and efficient strategy to delay the onset and mitigate the progression of sarcopenia in older adults. © 2009 International Union of Biochemistry and Molecular Biology, Inc.
Teaching undergraduate students to model use cases using tree diagram concepts
Authors: Juárez‐Ramírez Reyes , Licea Guillermo , Cristóbal‐Salas Alfredo
Published: February 2009

A new approach for use cases description is exposed. It is based on four mathematical concepts: sequential events, possible results, tree diagrams, and permutations. This approach pretends to encourage undergraduate students to use formal concepts in software engineering, in order to reduce the lack of formality that this discipline suffers. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 18: 77–86, 2010; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20190
The advantages of using Mind Map for learning web Dynpro
Authors: Cristea Ana Daniela , Berdie Adela Diana , Osaci Mihaela , Chirtoc Daniel
Published: February 2009

This article presents an easy study technique, based on a complex and modern informational technology, the Web programming on integrated systems, in particular Web Dynpro Java. The project developed for this learning technique is realised in Mind Map and combines an assembly of utilities, from the transparent presentation of complex concepts to comparative studies and tests used to verify the knowledge, all these being based on a rich collection of applications. Using this learning technique, it is possible to receive either an assembly image on the technology, or to deeply get into the subtlest details. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 19: 201–207, 2011
Experimental Validation of Thin‐layer Drying Models
Authors: Sander A. , Kardum J. P.
Published: February 2009

The present work was aimed at investigating the applicability of the proposed correlation equations that link the coefficients of the thin‐layer equations. Materials of different properties were chosen and dried in four types of laboratory dryers. The experimental data were approximated applying the commonest thin‐layer equations: the Lewis equation, the modified Page's model, and Fick's second law. The best match was achieved with the modified Page's model. The applicability of the stated literature correlations was confirmed. Irrespective of the match between measuring data (X = f(t)) and Lewis equation, the evaluated drying constant K allowed evaluation of the parameters of the employed two‐parameter models.
Quest for Environmentally Benign Ligands for Actinide Separations: Thermodynamic, Spectroscopic, and Structural Characterization of UVI Complexes with Oxa‐Diamide and Related Ligands
Authors: Tian Guoxin , Rao Linfeng , Teat Simon J. , Liu Guokui
Published: February 2009

Complexation of UVI with N,N,N′,N′‐tetramethyl‐3‐oxa‐glutaramide (TMOGA) and N,N‐dimethyl‐3‐oxa‐glutaramic acid (DMOGA; see picture) was studied in comparison with their dicarboxylate analogue, oxydiacetic acid (ODA). The stability constants, enthalpy, and entropy of complexation all decrease in the order ODA> DMOGA>TMOGA, showing that the complexation is entropy driven and the substitution of a carboxylate group with an amide group reduces the strength of complexation with UVI due to the decrease in the entropy of complexation (see figure).

magnified image

Complexation of UVI with N,N,N′,N′‐tetramethyl‐3‐oxa‐glutaramide (TMOGA) and N,N‐dimethyl‐3‐oxa‐glutaramic acid (DMOGA) was studied in comparison with their dicarboxylate analogue, oxydiacetic acid (ODA). Thermodynamic parameters, including stability constants, enthalpy, and entropy of complexation, were determined by spectrophotometry, potentiometry, and calorimetry. Single‐crystal X‐ray diffraction, EXAFS spectroscopy, FT‐IR absorption spectroscopy, and laser‐induced luminescence spectroscopy were used to obtain structural information on the UVI complexes. Like ODA, TMOGA and DMOGA form tridentate UVI complexes, with three oxygen atoms (the amide, ether, and/or carboxylate oxygen) coordinating to the linear UO22+ ion through the equatorial plane. The stability constants, enthalpy, and entropy of complexation all decrease in the order ODA>DMOGA>TMOGA, showing that the complexation is entropy driven and the substitution of a carboxylate group with an amide group reduces the strength of complexation with UVI due to the decrease in the entropy of complexation. The trend in the thermodynamic stability of the complexes correlates very well with the structural and spectroscopic data obtained by single‐crystal X‐ray diffraction, FT‐IR spectroscopy, and laser‐induced luminescence spectroscopy.
The Nature and Sequence of the Amino Acid Aglycone Strongly Modulates the Conformation and Dynamics Effects of Tn Antigen's Clusters
Authors: Corzana Francisco , Busto Jesús H. , García de Luis Marisa , Jiménez‐Barbero Jesús , Avenoza Alberto , Peregrina Jesús M.
Published: February 2009

All in a cluster: The selected sequence has a crucial influence on both the orientation and flexibility of the carbohydrate moiety in mucin‐type glycopeptides (see picture). This feature can be explained through the varied conformational behavior of the glycosidic linkage of the Thr residue when compared with the Ser residue (see figure). On this basis, and taking into account that these carbohydrates presumably interact with components of the immune system, these findings could be helpful in the design of new cancer vaccines.

magnified image

Synthetic oligosaccharide vaccines based on carbohydrate epitopes are currently being evaluated as potential immunotherapeutics in the treatment of cancer. In an effort to study the role that the amino acid moiety (L‐serine and/or L‐threonine residues) plays on the global shape of the resulting glycopeptides and on the dynamics of the carbohydrate moiety, diverse glycopeptides based on the Tn antigen have been synthesized and studied in aqueous solution by combining NMR spectroscopic experiments and molecular dynamics simulations. Our results demonstrate that although the effect of the clustering of Tn on the peptide backbone is not remarkable, it substantially modifies the dynamics, and thus, the presentation features of the carbohydrate moiety. In fact, the selected sequence has a crucial influence on both the orientation and flexibility of the sugar region. Thus, although a serine–threonine pair shows a well‐defined spatial disposition of the Tn epitopes, its analogue sequence threonine–serine allows a certain degree of mobility that could favor the interaction with a diversity of receptors without a major energy penalty. These features can be explained by attending to the different conformational behavior of the glycosidic linkage of threonine‐containing glycopeptides when compared with those of the serine analogues. On this basis, and taking into account that these carbohydrates interact with components of the immune system, these findings could have implications for further design of new cancer vaccines.
Nickel Complexes of a Pincer Amidobis(amine) Ligand: Synthesis, Structure, and Activity in Stoichiometric and Catalytic CC Bond‐Forming Reactions of Alkyl Halides
Authors: Vechorkin Oleg , Csok Zsolt , Scopelliti Rosario , Hu Xile
Published: February 2009

Get a grip! NiII complexes of the new pincer amidobis(amine) ligand are described. The Ni chloride complex catalyzes Kumada–Corriu–Tamao coupling of unactivated alkyl halides with alkyl Grignard reagents, as well as double C–C coupling of CH2Cl2 with alkyl Grignard reagents (see schemes).

magnified image

The synthesis, properties, and reactivity of nickel(II) complexes of a newly developed pincer amidobis(amine) ligand (MeNN2) are described. Neutral or cationic complexes [(MeNN2)NiX] (X=OTf (6), OC(O)CH3 (7), CH3CN (8), OMe (9)) were prepared by salt metathesis or chloride abstraction from the previously reported [(MeNN2)NiCl] (1). The Lewis acidity of the {(MeNN2)Ni} fragment was measured by the 1H NMR chemical shift of the coordinated CH3CN molecule in 8. Electrochemical measurements on 1 and 8 indicate that the electron‐donating properties of NN2 are similar to those of the analogous amidobis(phosphine) (pnp) ligands. The solid‐state structures of 6–8 were determined and compared to those of 1 and [(MeNN2)NiEt] (3). In all complexes, the MeNN2 ligand coordinates to the NiII ion in a mer fashion, and the square‐planar coordination sphere of the metal is completed by an additional donor. The coordination chemistry of MeNN2 thus resembles that of other three‐dentate pincer ligands, for example, pnp and arylbis(amine) (ncn). Reactions of 2 with alkyl monohalides, dichlorides, and trichlorides were investigated. Selective CC bond formation was observed in many cases. Based on these reactions, efficient Kumada–Corriu–Tamao coupling of unactivated alkyl halides and alkyl Grignard reagents with 1 as the precatalyst was developed. Good yields were obtained for the coupling of primary and secondary iodides and bromides. Double C–C coupling of CH2Cl2 with alkyl Grignard reagents by 1 was also realized. The scope and limitations of these transformations were studied. Evidence was found for a radical pathway in Ni‐catalyzed C–C cross‐coupling reactions, which involves NiII alkyl intermediates.
Self‐Assembly of Bis(merocyanine) Tweezers into Discrete Bimolecular π‐Stacks
Authors: Lohr Andreas , Grüne Matthias , Würthner Frank
Published: February 2009

Dipolar aggregation: Examples of a novel class of tweezer molecules have been constructed through the tethering of two dipolar merocyanine chromophores. The electrostatic‐interaction‐directed self‐assembly of these tweezers affords centrosymmetric bimolecular complexes with a unique aggregate geometry of four π‐stacked chromophores (see picture) with an alternating arrangement of their dipole moments and very high dimerization constants, even in the good solvating solvent chloroform.

magnified image

Examples of a novel class of tweezer molecules have been constructed through the tethering of two dipolar merocyanine chromophores by a naphthalenedimethylene or dimethylenediphenylmethane spacer. The electrostatic‐interaction‐directed self‐assembly of these bis(merocyanine) tweezers affords centrosymmetric bimolecular complexes with very high dimerization constants of up to >109 M−1, even in the good solvating solvent chloroform. This pronounced self‐association of the bis(merocyanine) tweezers is attributed to the strongly dipolar nature of the merocyanine chromophores and a unique aggregate geometry of four π‐stacked chromophores with an alternating arrangement of their dipole moments. The structural assignment of the tetrachromophoric π‐stack has been accomplished by MALDI‐TOF mass spectrometry and ROESY NMR spectroscopy. Furthermore, molecular modeling studies have accounted for the relationships between the dimerization constants and optical properties of the bimolecular complexes of the present bis(merocyanine) dyes and the structure of the spacer and the positions at which the merocyanine chromophores are attached.
Rhodium(I)‐Catalyzed Reductive Cyclocarbonylation of Internal Alkynes: Atom‐Economic Process for Synthesis of 2‐Cyclopenten‐1‐ones, 5‐Alkylidenefuran‐2(5 H)‐ones and Indan‐1‐ones
Authors: Huang Qiufeng , Hua Ruimao
Published: February 2009

Economical atoms: 2‐Cyclopenten‐1‐ones, 5‐alkylidenefuran‐2(5 H)‐ones and indan‐1‐ones have been synthesized by atom‐economic reductive cyclocarbonylation of internal alkynes with carbon monoxide catalyzed by [{RhCl(CO)2}2]/CO(NH2)2 in the presence of water (see scheme).

magnified image

The reductive cyclocarbonylation of internal alkynes with carbon monoxide catalyzed by [{RhCl(CO)2}2]/CO(NH2)2 in the presence of water has been investigated. Dialkyl alkynes underwent a reductive [2+2+1] cyclocarbonylation to afford selectively cis‐2‐cyclopenten‐1‐ones in high yields. In the cases of diarylacetylenes used, both trans‐2‐cyclopenten‐1‐ones and 5‐alkylidenefuran‐2(5 H)‐ones were obtained, and the presence of electron‐withdrawing group on the benzene ring enhanced the formation of 5‐alkylidenefuran‐2(5 H)‐ones. On the other hand, ortho‐substituted diarylacetylenes underwent a reductive [4+1] cyclocarbonylation to produce selectively indan‐1‐ones in good yields.
Divalent Silicon(0) Compounds
Authors: Takagi Nozomi , Shimizu Takayasu , Frenking Gernot
Published: February 2009

Bridge of Si's: Quantum‐chemical calculations suggest that the bonding situation in the recently synthesized “trisilaallene” is better described in terms of donor–acceptor interactions between two silylene ligands L and a naked silicon atom Si, which carries two lone‐pair orbitals, yielding the silylone SiL2. Further silylones SiL2 with different donor ligands Si have also been calculated, which might be possible to synthesize.

magnified image

Quantum‐chemical calculations of the geometries and electronic structures of a series of dicoordinated silicon compounds SiL2, in which L is a five‐membered cyclic species suggest that the molecules are divalent silicon(0) compounds that possess two L→Si donor–acceptor bonds and two lone‐pair MOs with π and σ symmetry at silicon. The classification as a dicoordinate silicon compound with L→Si←L donor–acceptor bonds applies not only to molecules in which L is an N‐heterocyclic carbene but also when L is a cyclic silylene. The recently synthesized “trisilaallene” (S. Ishida, T. Iwamoto, C. Kabuto, M. Kira, Nature 2003, 421, 725), which has a bending angle of 136.5o for the central moiety, and which was written as SiSiSi, is probably better considered as a divalent silicon(0) compound. We suggest the name silylones for the latter species in analogy to silylenes which identify divalent SiII compounds. This bonding interpretation explains the theoretically predicted large values for the first and second proton affinities and for the large bond dissociation energies for one and two BH3 ligands. The calculations predict that the first protonation of the divalent silicon(0) compounds takes place at the π lone‐pair orbital, which yields protonated silylones that have a pyramidal arrangement of the ligands at the central tricoordinate silicon atom. Silylones SiL2 could be interesting ligands for transition‐metal compounds. The calculated structures and bonding situation of the analogous carbon compounds are also reported.
ChemInform Abstract: Structure and Bonding in Cyclic Isomers of B2AlHnm (n = 3—6, m = ‐2 to +1): A Comparative Study with B3Hnm, BAl2Hnm and Al3Hnm
Authors: Mallick Dibyendu , Parameswaran Pattiyil , Jemmis Eluvathingal D.
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Crystal Structure and Lattice Dynamics of Sr3Y(BO3)3.
Authors: Maczka M. , Waskowska A. , Majchrowski A. , Kisielewski J. , Szyrski W. , Hanuza J.
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: X‐Ray and Neutron Powder Diffraction Studies of Ba(NdxY2‐x)CuO5.
Authors: Liu G. , Huang Q. , Kaduk J. A. , Yang Z. , Lucas C. , Wong‐Ng W.
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthesis, Raman and Rietveld Analysis of Thorium Diphosphate.
Authors: Clavier Nicolas , Wallez Gilles , Dacheux Nicolas , Bregiroux Damien , Quarton Michel , Beaunier Patricia
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: General Synthesis and Structural Evolution of a Layered Family of Ln8(OH)20Cl4×nH2O (Ln: Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Y).
Authors: Geng Fengxia , Matsushita Yoshitaka , Ma Renzhi , Xin Hao , Tanaka Masahiko , Izumi Fujio , Iyi Nobuo , Sasaki Takayoshi
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Crystal and Electronic Structures, Luminescence Properties of Eu2+‐Doped Si6‐zAlzOzN8‐z and MySi6‐zAlz‐yOz+yN8‐z‐y (M: 2Li, Mg, Ca, Sr, Ba).
Authors: Li Y. Q. , Hirosaki N. , Xie R. J. , Takeda T. , Mitomo M.
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Unconventional Superconductivity in Ba0.6K0.4Fe2As2 from Inelastic Neutron Scattering.
Authors: Christianson A. D. , et al. et al.
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthesis, Crystal Structure and Magnetic Properties of a New Pillared Perovskite La5Mo2.75V1.25O16.
Authors: Ramezanipour Farshid , Derakhshan Shahab , Greedan John E. , Cranswick Lachlan M. D.
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: The Isothermal Section of the Dy—Fe—Ge Ternary System at 773 K.
Authors: Zhuang Y. H. , Ma C. H. , Li K. F. , Chen X.
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: The Isothermal Section of the Gd—Fe—Ge Ternary System at 773 K.
Authors: Zhuang Y. H. , Li K. F. , Ma C. H. , Chen X.
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthesis, Crystal Structure and NLO Property of a Nonmetal Pentaborate [C6H13N2] [B5O6(OH)4].
Authors: Liu Huan‐Xin , Liang Yun‐Xiao , Jiang Xiao
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Temperature Influence on the Formation of Selenidoantimonates: Solvothermal Syntheses, Crystal Structures and Thermal Properties of [Ni(dien)2]2Sb2Se6, [Mn(dien)2]2(SbSe4)(Cl), [Co(dien)2]2(SbSe4)(Br), and [Co(dien)2]3(SbSe4)2.
Authors: Jin Qin‐yan , Zhu Ai‐mei , Pan Ying‐li , Jia Ding‐xian , Zhang Yong , Gu Jian‐sheng
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Nitridogermanate Nitrides Sr7[GeN4]N2 and Ca7[GeN4]N2: Synthesis Employing Sodium Melts, Crystal Structure, and Density‐Functional Theory Calculations.
Authors: Junggeburth Sebastian C. , Oeckler Oliver , Johrendt Dirk , Schnick Wolfgang
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Syntheses, Structures, and Magnetic and Optical Properties of the Compounds [Hg3Te2][UCl6] and [Hg4As2][UCl6].
Authors: Bugaris Daniel E. , Ibers James A.
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: A Continuous Symmetry Measure of [4Fe—4S]+ Core Distortions and Analysis of Supramolecular Synthons in Crystal Structures of (Et4N)3 [Fe4S4Cl4]×Et4NCl at 100 and 295 K.
Authors: Hagen Karl S. , Uddin Mohammad
Published: February 2009

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.