bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and characterization of novel hyperbranched poly(amido amine)s from Michael addition polymerizations of trifunctional amines with diacrylamides
Authors: Wang Ding , Liu Ye , Hong Chun‐Yan , Pan Cai‐Yuan 
Published: September 2005

AbstractNovel hyperbranched poly(amido amine)s containing tertiary amines in the backbones and acryl as terminal groups were synthesized via the Michael addition polymerizations of trifunctional amines with twofold molar diacrylamide. The hyperbranched structures of these poly(amido amine)s were verified by 13C NMR (INVGATE). The polymerization mechanisms were clarified by following the polymerization process with NMR method, and the results show that the reactivity of secondary amine formed in situ is much lower than that of the secondary amine in 1‐(2‐aminoethyl) piperazine (AEPZ) ring and the primary amine. The secondary amine formed in situ was almost kept out of the reaction before the primary and secondary amines in AEPZ were consumed, leading to the formation of the AB2 intermediate, and the further reaction of the AB2 yielded the hyperbranched polymers. The molecular weights and properties of poly(amindo amine)s obtained were characterized by GPC, DSC, and TGA, respectively. Based on the reaction of active acryl groups in the polymers obtained with glucosamine, hyperbranched polymers containing sugar were formed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5127–5137, 2005
Exit surface dependence of the wavefunction measured and corrected by means of off‐axis electron holography
Authors: Lehmann Michael 
Published: September 2005

AbstractIn high‐resolution transmission electron microscopy (HRTEM), the recorded image intensity of a crystal, oriented on a low‐index zone‐axis, strongly depends on aberrations, in particular on defocus. However, already slight deviations of the exit surface from the incident plane electron wave causes a strong position‐dependent defocus, which, in the past, has rarely been considered in the analysis of HRTEM micrographs. Using off‐axis electron holography, the complete electron wave is available in both real space and Fourier space so that the reconstructed electron wave can be back‐propagated to the corresponding exit plane. Based on the thorough analysis of amplitude and phase of partial waves stemming from single reflections, a novel correction procedure is outlined yielding the object exit‐wave directly at the exit surface of the object. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kernel energy method: Basis functions and quantum methods
Authors: Huang Lulu , Massa Lou , Karle Jerome 
Published: September 2005

AbstractThe kernel energy method (KEM) has been illustrated with peptides and has been shown to reduce the computational difficulty associated with obtaining ab initio quality quantum chemistry results for large biological compounds. In a recent paper, the method was illustrated by application to 15 different peptides, ranging in size from 4 to 19 amino acid residues, and was found to deliver accurate Hartree–Fock (HF) molecular energies within the model, using Slater‐type orbital (STO)‐3G basis functions. A question arises concerning whether the results obtained from the use of KEM are wholly dependent on the STO‐3G basis functions that were employed, because of their relative simplicity, in the first applications. In the present work, it is shown that the accuracy of KEM does not depend on a particular choice of basis functions. This is done by calculating the ground‐state energy of a representative peptide, ADPGV7B, containing seven amino acid residues, using seven different commonly employed basis function sets, ranging in size from small to medium to large. It is shown that the accuracy of the KEM does not vary in any systematic way with the size or mathematical completeness of the basis set used, and good accuracy is maintained over the entire variety of basis sets that have been tested. Both approximate HF and density functional theory (DFT) calculations are made. We conclude that the accuracy inherent in the KEM is not dependent on a particular choice of basis functions. The first application, to 15 different peptides mentioned above, employed only HF calculations. A second question that arises is whether the results obtained with the use of KEM will be accurate only within the HF approximation. Therefore, in the present work we also study whether KEM is applicable across a variety of quantum computational methods, characterized by differing levels of accuracy. The peptide, Zaib4, containing 74 atoms, was used to calculate its energy at seven different levels of accuracy. These include the semi‐empirical methods, AM1 and PM5, a DFT B3LYP model, and ab initio HF, MP2, CID, and CCSD calculations. KEM was found to be widely applicable across the spectrum of quantum methods tested. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Theoretical study of multiphoton processes in diatomic molecules
Authors: Sugimori Kimikazu , Ito Tomoya , Nagao Hidemi , Nishikawa Kiyoshi 
Published: September 2005

AbstractWe investigate multiphoton processes in diatomic molecules. We adopt the Morse oscillator model for the vibrational state of molecules and simulate the population transfer between vibrational levels caused by molecule–laser interaction. The ground‐state energy is calculated by the quadratic configurational interaction (QCISD) level ab initio molecular orbital calculation, and the potential energy curve of the ground state is fitted by the Morse potential curve to evaluate the discrete vibrational levels. An intense laser field generally causes the nonlinear optical processes in molecules, such as multiphoton excitation and ionization. We investigate the 1‐, 2‐, 3‐, and 4‐photon absorption processes in H2 and OH molecules in relation to the laser intensity in the picosecond (ps) regime. We also apply the stimulated Raman adiabatic passage (STIRAP) method to the efficient generation of the highly vibrational excited state, using a couple of the simultaneous 2‐photon absorption processes as the Stokes and pump processes. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
A general modelling and control framework for electrostatically actuated mechanical systems
Authors: Maithripala D. H. S. , Kawade B. D. , Berg J. M. , Dayawansa W. P. 
Published: September 2005

AbstractThis paper presents a geometric framework for the stabilization and control of a general class of electrostatically actuated mechanical systems. Microelectromechanical systems (MEMS), such as micromirrors, are one motivating application for this work. There wavelengths of applications of interest lead to positioning requirements on the order of 40–100 nm. Furthermore, electrostatic actuation is poised to be the method of choice for the emerging field of nanoelectromechanical systems (NEMS), and the approach presented should be applicable there as well. The class of devices under study consists of a movable, rigid, grounded electrode, with a variety of allowable rotational and/or translational degrees of freedom, and a set of multiple, fixed, independently addressable, drive electrodes. A key contribution of this paper places general electrostatic forces in a framework suitable for passivity‐based control. The configuration space of the movable body is assumed to have the structure of a simple mechanical system on a Lie group, and stabilizing static and dynamic feedback control laws are derived in terms of co‐ordinate‐independent geometric formulas. To obtain controllers for a specific device it is then necessary only to evaluate these formulas. Appropriate approximations may be applied to make the computations more tractable. The static output feedback controller requires only measurement of the charge and voltage on each drive electrode to provide almost‐global stabilization of a desired feasible configuration, but performance is limited by the natural dynamics of the mechanical subsystem. Performance may be improved using dynamic output feedback, but additional information is needed, typically in the form of a model relating electrode capacitances to the system configuration. We demonstrate the controller computations on a representative MEMS, and validate performance using ANSYS simulations. Copyright © 2005 John Wiley & Sons, Ltd.
REPTILES WITH HOLES
Authors: Jordan Francis , Ngai Sze-Man 
Published: September 2005

AbstractCroft, Falconer and Guy asked: what is the smallest integer $n$ such that an $n$-reptile in the plane has a hole? Motivated by this question, we describe a geometric method of constructing reptiles in $\mathbb{R}^d$, especially reptiles with holes. In particular, we construct, for each even integer $n\ge4$, an $n$-reptile in $\mathbb{R}^2$ with holes. We also answer some questions concerning the topological properties of a reptile whose interior consists of infinitely many components.
THE RELATIVE PICARD GROUP OF A COMODULE ALGEBRA AND HARRISON COHOMOLOGY
Authors: Caenepeel S. , Guédénon T. 
Published: September 2005

AbstractLet $A$ be a commutative comodule algebra over a commutative bialgebra $H$. The group of invertible relative Hopf modules maps to the Picard group of $A$, and the kernel is described as a quotient group of the group of invertible group-like elements of the coring $A\otimes H$, or as a Harrison cohomology group. Our methods are based on elementary $K$-theory. The Hilbert 90 theorem follows as a corollary. The part of the Picard group of the coinvariants that becomes trivial after base extension embeds in the Harrison cohomology group, and the image is contained in a well-defined subgroup $E$. It equals $E$ if $H$ is a cosemisimple Hopf algebra over a field.
A CRITERION FOR ERDŐS SPACES
Authors: Dijkstra Jan J. 
Published: September 2005

AbstractIn 1940 Paul Erdős introduced the ‘rational Hilbert space’, which consists of all vectors in the real Hilbert space $\ell^2$ that have only rational coordinates. He showed that this space has topological dimension one, yet it is totally disconnected and homeomorphic to its square. In this note we generalize the construction of this peculiar space and we consider all subspaces $\mathcal{E}$ of the Banach spaces $\ell^p$ that are constructed as ‘products’ of zero-dimensional subsets $E_n$ of $\mathbb{R}$. We present an easily applied criterion for deciding whether a general space of this type is one dimensional. As an application we find that if such an $\mathcal{E}$ is closed in $\ell^p$, then it is homeomorphic to complete Erdős space if and only if $\dim\mathcal{E}>0$ and every $E_n$ is zero dimensional.
Undernutrition, infection and immune function
Authors: Calder Philip C. , Jackson Alan A. 
Published: September 2005

AbstractUndernutrition and infection are the major causes of morbidity and mortality in the developing world. These two problems are interrelated. Undernutrition compromises barrier function, allowing easier access by pathogens, and compromises immune function, decreasing the ability of the host to eliminate pathogens once they enter the body. Thus, malnutrition predisposes to infections. Infections can alter nutritional status mediated by changes in dietary intake, absorption and nutrient requirements and losses of endogenous nutrients. Thus, the presence of infections can contribute to the malnourished state. The global burden of malnutrition and infectious disease is immense, especially amongst children. Childhood infections impair growth and development. There is a role for breast-feeding in protection against infections. Key nutrients required for an efficient immune response include vitamin A, Fe, Zn and Cu. There is some evidence that provision of the first three of these nutrients does improve immune function in undernourished children and can reduce the morbidity and mortality of some infectious diseases including measles, diarrhoeal disease and upper and lower respiratory tract infections. Not all studies, however, show benefit of single nutrient supplementation and this might be because the subjects studied have multiple nutrient deficiencies. The situation regarding Fe supplementation is particularly complex. In addition to immunization programmes and improvement of nutrient status, there are important roles for maternal education, improved hygiene and sanitation and increased supply of quality water in the eradication of infectious diseases.
Herbal products: active constituents, modes of action and quality control
Authors: Wills Ron B.H. , Bone Kerry , Morgan Michelle 
Published: September 2005

AbstractAn overview is given of the current position of medicinal herbs in general in relation to usage, market and production, types of pharmacological activity and how they differ from conventional drugs. The increasing importance of quality and manufactured products is also discussed. A more detailed consideration of these issues is given in relation to echinacea, valerian and St John's wort as these herbs are well studied, are market leaders and have widespread community usage.
Plant polyphenols in cancer and heart disease: implications as nutritional antioxidants
Authors: Duthie Garry G. , Duthie Susan J. , Kyle Janet A. M. 
Published: September 2005

AbstractCertain dietary antioxidants such as vitamin E and vitamin C are important for maintaining optimum health. There is now much interest in polyphenolic products of the plant phenylpropanoid pathway as they have considerable antioxidant activityin vitroand are ubiquitous in our diet. Rich sources include tea, wine, fruits and vegetables although levels are affected by species, light, degree of ripeness, processing and storage. This confounds the formulation of databases for the estimation of dietary intakes. Most attention to date has focused on the flavonoids, a generic term which includes chalcones, flavones, flavanones, flavanols and anthocyanins. There is little convincing epidemiological evidence that intakes of polyphenols are inversely related to the incidence of cancer whereas a number of studies suggest that high intakes of flavonoids may be protective against CHD. In contrast, numerous cell culture and animal models indicate potent anticarcinogenic activity by certain polyphenols mediated through a range of mechanisms including antioxidant activity, enzyme modulation, gene expression, apoptosis, upregulation of gap junction communication and P-glycoprotein activation. Possible protective effects against heart disease may be due to the ability of some polyphenols to prevent the oxidation of LDL to an atherogenic form although anti-platelet aggregation activity and vasodilatory properties are also reported. However, some polyphenols are toxic in mammalian cells. Thus, until more is known about their bioavailability, metabolism and intracellular location, increasing intakes of polyphenols by supplements or food fortification may be unwise.
Phytate and phytase: consequences for protein utilisation
Authors: Selle P H , Ravindran V , Caldwell A , Bryden W. L 
Published: September 2005

AbstractThe excretion of large amounts of P in effluent from intensive pig and poultry units is indicative of the poor availability of phytate-bound P in plant-derived feed ingredients. This environmental problem prompted the development and acceptance of microbial phytase feed enzymes for single-stomached animals. Their introduction led to an increasing recognition that phytate may have adverse effects on protein utilisation in addition to P. Consequently, the nutritional relevance of protein–phytate interactions for pigs and poultry is considered in the present review. Since the current understanding of the effects of protein–phytate interactions comes mainly from responses obtained to added phytase, literature on the influence of microbial phytases on amino acid digestibility and utilisation is summarised, followed by a discussion of possible mechanisms contributing to the negative effects of phytate. However, the rationale for the protein responses to added phytase remains largely speculative, and several modes of action are probably involved. It may be that the release of protein from protein–phytate complexes occurring naturally in feed ingredients, the prevention of formation of binary and ternary protein–phytate complexes within the gut, the alleviation of the negative impact of phytate on digestive enzymes and the reduction in endogenous amino acid losses are all contributing factors. A better understanding of the mechanisms of protein–phytate interactions and the modes of action of exogenous phytase enzymes is clearly desirable. Studies are also needed to identify and quantify the factors that contribute to the variable amino acid responses to added phytase. It appears that the relative solubilities of phytate salts and proteins from different feed ingredients and their effects on the extent of protein–phytate complex formation, coupled with variations in the effectiveness of phytase in different dietary contexts, may be the major factors responsible.
Perspectives on ruminant nutrition and metabolism. II. Metabolism in ruminant tissues
Authors: Annison E. F , Bryden W. L 
Published: September 2005

AbstractThe discovery of the dominance of short-chain fatty acids as energy sources in the 1940s and 1950s, as discussed in part I of this review (Annison & Bryden, 1998) led to uncertainties concerning the interrelationships of glucose and acetate in ruminant metabolism. These were resolved in the following decade largely by use of14C-labelled substrates. Although only small amounts of glucose are absorbed in most dietary situations, glucose availability to ruminant tissues as measured by isotope dilution was shown to be substantial, indicating that gluconeogenesis is a major metabolic activity in both fed and fasted states. Studies with14C-labelled glucose and acetate revealed that in contrast to non-ruminants, acetate and not glucose is the major precursor of long-chain fatty acids in ruminant tissues. Interest in the measurement of energy metabolism in livestock grew rapidly from the 1950s. Most laboratories adopted indirect calorimetry and precise measurements of the energy expenditure of ruminants contributed to the development of new feeding systems. More recently, alternative approaches to the measurement of energy expenditure have included the use of NMR spectroscopy, isotope dilution and the application of the Fick principle to measure O2consumption in the whole animal and in defined tissues. The refinement of the classical arterio-venous difference procedure in the study of mammary gland metabolism in the 1960s, particularly when combined with isotope dilution, encouraged the use of these methods to generate quantitative data on the metabolism of a range of defined tissues. The recent introduction of new methods for the continuous monitoring of both blood flow and blood O2content has greatly increased the precision and scope of arterio-venous difference measurements. The impact of data produced by these and other quantitative procedures on current knowledge of the metabolism of glucose, short-chain fatty acids and lipids, and on N metabolism, is outlined. The role of the portal-drained viscera and liver in N metabolism is discussed in relation to data obtained by the use of multi-catheterized animals. Protein turnover, and the impact of stress (physical, social and disease related) on protein metabolism have been reviewed. The growth of knowledge of mammary gland metabolism and milk synthesis since the first quantitative studies in the 1960s has been charted. Recent findings on the regulation of amino acid uptake and utilization by the mammary gland, and on the control of milk secretion, are of particular interest and importance.
Understanding the nutritional chemistry of lupin (Lupinus spp.) seed to improve livestock production efficiency
Authors: van Barneveld Robert J. 
Published: September 2005

AbstractIn their raw, unprocessed form, lupins have many desirable characteristics for feeding both ruminants and single-stomached animals. An emphasis on these desirable characteristics when formulating diets, combined with an advanced knowledge of how components of lupins can influence nutritional value, will ensure they make a cost-effective contribution to livestock diets. The main lupin species used in livestock diets include Lupinus albus, L. angustifolius and L. luteus. Supplementation of ruminant diets with lupins has been shown to have many positive effects in terms of growth and reproductive efficiency, comparable with supplements of cereal grain. The true value of lupins in ruminants, however, can only be determined following a better definition of animal requirements and a closer match of ration specifications. Pigs can effectively utilize L. angustifolius and L. luteus, but detailed research has yet to reveal the reason for poor utilization of diets containing L. albus. Poultry can tolerate high levels of lupins in their diets but levels are often restricted to avoid problems associated with excess moisture in the excreta. Variable responses to enzymes have been observed when attempting to rectify this problem. Lupins have unique carbohydrate properties characterized by negligible levels of starch, high levels of soluble and insoluble NSP, and high levels of raffinose oligosaccharides, all of which can affect the utilization of energy and the digestion of other nutrients in the diet. In addition to carbohydrates, an understanding of lupin protein, lipid and mineral composition together with a knowledge of potential anti-nutritional compounds is required if the use of this legume is to be optimized.
Prevention of Toxoplasmosis in Pregnancy: Knowledge of Risk Factors
Authors: Kravetz Jeffrey D. , Federman Daniel G. 
Published: September 2005

Background. Infection with Toxoplasma gondii is common and usually asymptomatic, although it can have catastrophic
consequences in a pregnant woman if passed to her developing fetus. Counseling of pregnant women about risk factor reduction may reduce the risk of congenital toxoplasmosis. This study was undertaken to assess and compare the knowledge
of obstetricians and internists or family practitioners regarding well‐established risk factors for toxoplasmosis infection.Methods. The study surveyed 102 obstetricians, internists and family practitioners to assess their knowledge of risk factors for toxoplasmosis infection as well as their practices for primary prevention counseling of pregnant women. Responses were
analyzed for differences.Results. Obstetricians were more likely than internists or family practitioners to provide appropriate counseling on reducing the two most common risk factors for toxoplasmosis infection (undercooked meat consumption and gardening without
gloves). However, over one quarter of all participants inappropriately advised pregnant women to avoid all cat contact. Obstetricians, internists and family practitioners were all likely to fail to identify undercooked meat consumption as the primary risk factor for toxoplasmosis transmission.Conclusions. Obstetricians appear to provide more appropriate counseling for primary prevention of toxoplasmosis than internists and family practitioners, but both groups of physicians inappropriately advised avoidance of all cat contact. Education of obstetricians, internists and family practitioners on risk factors for toxoplasmosis transmission is needed and may lower the rate of congenital toxoplasmosis as well as decrease the frequency of cat abandonment during pregnancy.