bluuebunny/crossref_metadata_2025 huggingface dataset:
Solutions to the Percus-Yevick Equation
Authors: Broyles A. A.
Published: July 2004

The radial distribution function for a classical fluid of particles interacting with the Lennard-Jones potential has been computed by solving the Percus-Yevick integral equation numerically. The solutions and the quantities, p/nkT and E/NkT, are compared with those obtained by Wood and Parker using Monte Carlo techniques. The radial distribution functions agree to better than 15% beyond the first points where they are unity while the thermodynamic quantities differ by, at most, 3% from the range of Monte Carlo values for cases where the system is believed to be in a liquid state. The quantity K=−(1/V)(∂V/∂p)N,T,has also_been computed.
Mass Spectra and Metastable Transitions in Isotopic Nitrous Oxides
Authors: Begun G. M. , Landau L.
Published: July 2004

The mass spectra of the four species N14N14O, N14N15O, N15N14O, and N15N15O have been recorded. The (NO)+ fragment produced was found to be formed by rearrangement, as well as by loss of the end nitrogen. The mass spectrum of each of the nitrous oxides contained ions corresponding to metastable transitions. These ions were shown to arise from both spontaneous and collision induced dissociation of the parent molecule ion (N2O)+. The electron impact dissociation of nitrous oxide is discussed.
Absorption and Fluorescence Spectra with Magnetic Properties of ErCl3
Authors: Dieke G. H. , Singh Shobha
Published: July 2004

The absorption and fluorescence spectra of ErCl3 diluted by LaCl3 are given with the Zeeman effects of many of the lines. All expected electronic levels to 30 000 cm—1 above the ground state are found, and their interpretation fits into the theoretically expected scheme. Examples are also given of the absorption and fluorescence spectrum of pure ErCl3 which show that the pure salt must have a structure quite different from that of LaCl3.
A Paramagnetic Species in Irradiated NaNO2
Authors: Zeldes Henry , Livingston Ralph
Published: July 2004

Single crystals of sodium nitrite were irradiated with Co60 gamma rays at 77°K and studied by the paramagnetic resonance method. An anisotropic three-line hyperfine spectrum associated with a single paramagnetic species was observed. The hyperfine structure arises from a nitrogen nucleus in the paramagnetic species at a position of mm point symmetry. The principal values of the g tensor and the hyperfine tensor were deduced as well as the directions of their principal axes. The paramagnetic species is believed to be NO2.
Homopolar Dipole
Authors: Coulson C. A. , Rogers Max T.
Published: July 2004

Numerical tables for the homopolar dipole or overlap moment μh.d. associated with various molecular orbitals (MO's) are presented. The present tables include values of μh.d./R for the common MO's constructed from linear combinations of atomic orbitals (the LCAO approximation), one of which is an 1s, 2s, 2pσ, 2pπ, 3s, or 3pσ orbital. The calculations employ approximate atomic orbitals of the Slater type. Formulas for x̄AB, the x coordinate of the centroid of negative charge for an electron in an MO, are given as functions of the parameters p=12R(ζA+ζB) and t=(ζA−ζB)/(ζA+ζB), where R is the internuclear distance, ζ (n—δ) is the effective nuclear charge found by the Slater rules, and (n—δ) is an effective quantum number. Values of μh.d./R are also given for some MO's in which one AO is a hybrid. The variation of μh.d. with the parameters p and t is shown graphically for certain MO's. The overlap moment μh.d. has been computed for various chemical bonds by use of the tables.

Overlap integrals for the AO combinations 1s—3dσ, 2s—5s, 2s—5pσ, 2pπ—3dπ, and 3s—3s were computed since these were not available in the literature over the necessary range of the variables.
Substituent Effects on the C13 and H1 Chemical Shifts in Monosubstituted Benzenes
Authors: Spiesecke H. , Schneider W. G.
Published: July 2004

The origin of the relative nuclear resonance shifts in monosubstituted benzenes has been investigated. In order to obtain more complete experimental information both C13 and H1 resonance shifts in a variety of aryl-X compounds were measured. The H1 resonances were measured on 5 mole % solutions in cyclohexane to minimize solvent effects; the carbon shifts were obtained from natural abundance C13 resonance measurements in the neat liquid. Unambiguous assignments of both H1 and C13 resonance spectra were made possible with the aid of deuterated compounds. The largest resonance shifts were observed for the carbon atom directly bonded to X. As in the corresponding CH3X compounds, these shifts arise primarily from the inductive and magnetic anisotropy effects of X. Magnetic anisotropy effects of X are also observable in both the C13 and H1 resonances at the ortho position. A very close correspondence between C13 and H1 resonances is observed at the para position, where the primary contribution to the relative shifts arises from resonance effects of X. This implies that the proton resonance responds to the π-electron density on the carbon to which it is bonded, and that under favorable conditions, both H1 and C13 resonance shifts might be employed to obtain information about the π-electron density distribution in aromatic systems. At the meta position the C13 resonance shifts are surprisingly small and uniform, indicating small or negligible inductive effects due to X, and there is no evident correlation with the meta-proton shifts. Both the C13 and H1 shifts at the para position show an approximate correlation with chemical reactivity parameters (Hammett σ constants) but no such correlation exists for the meta-carbon or meta-hydrogen shifts.
Value-Based Property Taxation: Options for Hungary
Authors: Szalai Ákos , Tassonyi Álmos T
Published: July 2004

Hungary is a small country with a very fragmented system of local government. Since 1990 the role of these governments has changed radically as has their level of responsibility. By contrast, the local taxation system still reflects the residue of the previous system. In the context of accession to the European Union, and decentralization initiatives being advocated by international agencies, there is a need to introduce different forms of local taxation. A value-based property tax would serve this purpose. Drawing upon North American experience, we analyze the issues involved in implementing such a system. The local capacity and the legislative parameters to make such a system work are also discussed.
Corporate Community Involvement in European and US Cities
Authors: van den Berg Leo , Braun Erik , Otgaar Alexander H J
Published: July 2004

We aim to identify the implications of corporate citizenship in general, and of collaboration between public and private actors in particular, for the development of cities. We analyse the changing behaviour of proactive firms in the field of community involvement, the spatial dimension of corporate citizenship, the added value of cross-sector partnerships, and the barriers to partnerships. We conclude that the trend of corporate community involvement provides new opportunities for the development of partnerships between proactive corporate citizens, city government, and other (public or private) organisations. However, the results suggest that the actual number of such partnerships is lower than expected. This lack of partnerships can be explained by looking at the internal organisation of companies and their potential partners, and the barriers in the coalition-forming process itself.
Regulating Food Risks: Rebuilding Confidence in Europe's Food?
Authors: Smith Everard , Marsden Terry , Flynn Andrew , Percival Alice
Published: July 2004

How can contemporary governments and regulation respond effectively to the growth of food risks at the same time as encouraging the further economic development of the European internal market? Taking the case of European food regulation during the ‘post-BSE’ period, this paper explores the changing dynamics of food regulation and accountability, and the interplay of influences that are shaping the new regulatory terrain. In examining three critical dimensions of change: (1) the maturing Europeanisation of UK policy; (2) the consumerisation and new institutionalisation of food policy and the wider participation of interest groups; and (3) the development of a more complex private-interest model of food regulation; the paper outlines a new conceptual model of contested regulation which incorporates the state, corporate and noncorporate private interests, consumers, and a variety of other social interests.
Oxidative stress and male reproductive biology
Authors: Aitken R. John , Baker Mark A.
Published: July 2004

Spermatozoa were the first cell type in which the cellular generation of reactive oxygen was demonstrated. This activity has now been confirmed in spermatozoa from all mammalian species examined including the rat, mouse, rabbit, horse, bull and human being. Under physiological circumstances, cellular redox activity is thought to drive the cAMP-mediated, tyrosine phosphorylation events associated with sperm capacitation. In addition to this biological role, human spermatozoa also appear to suffer from oxidative stress, with impacts on the normality of their function and the integrity of their nuclear and mitochondrial DNA. Recent studies have helped to clarify the molecular basis for the intense redox activity observed in defective human spermatozoa, the nature of the subcellular structures responsible for this activity and possible mechanisms by which oxidative stress impacts on these cells. Given the importance of oxidative damage in the male germ line to the origins of male infertility, early pregnancy loss and childhood disease, this area of sperm biochemistry deserves attention from all those interested in improved methods for the diagnosis, management and prevention of male-mediated reproductive failure.
The degenerate Y chromosome – can conversion save it?
Authors: Graves Jennifer A. Marshall
Published: July 2004

The human Y chromosome is running out of time. In the last 300 million years, it has lost 1393 of its original 1438 genes, and at this rate it will lose the last 45 in a mere 10 million years. But there has been a proposal that perhaps rescue is at hand in the form of recently discovered gene conversion within palindromes. However, I argue here that although conversion will increase the frequency of variation of the Y (particularly amplification) between Y chromosomes in a population, it will not lead to a drive towards a more functional Y. The forces of evolution have made the Y a genetically isolated, non-recombining entity, vulnerable to genetic drift and selection for favourable new variants sharing the Y with damaging mutations. Perhaps it will even speed up the decline of the Y chromosome and the onset of a new round of sex-chromosome differentiation. The struggle to preserve males may perhaps lead to hominid speciation.
Formation and characterization of an all-ferrous Rieske cluster and stabilization of the [2Fe-2S]
0
core by protonation
Authors: Leggate Ellen J. , Bill Eckhard , Essigke Timm , Ullmann G. Matthias , Hirst Judy
Published: July 2004

The all-ferrous Rieske cluster, [2Fe-2S]
0
, has been produced in solution and characterized by protein-film voltammetry and UV–visible, EPR, and Mössbauer spectroscopies. The [2Fe-2S]
0
cluster, in the overexpressed soluble domain of the Rieske protein from the bovine cytochrome
bc
1
complex, is formed at –0.73 V at pH 7. Therefore, at pH 7, the [2Fe-2S]
1+/0
couple is 1.0 V below the [2Fe-2S]
2+/1+
couple. The two cluster-bound ferrous irons are both high spin (S = 2), and they are coupled antiferromagnetically (–
J
≥ 30 cm
–1
,
H
=–2
J
S1·S2) to give a diamagnetic (S = 0) ground state. The ability of the Rieske cluster to exist in three oxidation states (2+, 1+, and 0) without an accompanying coupled reaction, such as a conformational change or protonation, is highly unusual. However, uncoupled reduction to the [2Fe-2S]
0
state occurs at pH > 9.8 only, and at high pH the intact cluster persists in solution for <1 min. At pH < 9.8, the all-ferrous cluster is stabilized significantly by protonation. A combination of experimental data and calculations based on density functional theory suggests strongly that the proton binds to one of the cluster μ
2
-sulfides, consistent with observations that reduced [3Fe-4S] clusters are protonated also. The implications for our understanding of coupled reactions at iron–sulfur clusters and of the factors that determine the relative stabilities of their different oxidation states are discussed.
Transparallel processing by hyperstrings
Authors: van der Helm Peter A.
Published: July 2004

Human vision research aims at understanding the brain processes that enable us to see the world as a structured whole consisting of separate objects. To explain how humans organize a visual pattern, structural information theory starts from the idea that our visual system prefers the organization with the simplest descriptive code, that is, the code that captures a maximum of visual regularity. Empirically, structural information theory gained support from psychological data on a wide variety of perceptual phenomena, but theoretically, the computation of guaranteed simplest codes remained a troubling problem. Here, the graph-theoretical concept of “hyperstrings” is presented as a key to the solution of this problem. A hyperstring is a distributed data structure that allows a search for regularity inO(2N) strings as if only one string of lengthNwere concerned. Thereby, hyperstrings enable transparallel processing, a previously uncharacterized form of processing that might also be a form of cognitive processing.
Therapeutic effects of PKC activators in Alzheimer's disease transgenic mice
Authors: Etcheberrigaray René , Tan Mathew , Dewachter Ilse , Kuipéri Cuno , Van der Auwera Ingrid , Wera Stefaan , Qiao Lixin , Bank Barry , Nelson Thomas J. , Kozikowski Alan P. , Van Leuven Fred , Alkon Daniel L.
Published: July 2004

Alzheimer's disease (AD) characteristically presents with early memory loss. Regulation of K+channels, calcium homeostasis, and protein kinase C (PKC) activation are molecular events that have been implicated during associative memory which are also altered or defective in AD. PKC is also involved in the processing of the amyloid precursor protein (APP), a central element in AD pathophysiology. In previous studies, we demonstrated that benzolactam (BL), a novel PKC activator, reversed K+channels defects and enhanced secretion of APPα in AD cells. In this study we present data showing that another PKC activator, bryostatin 1, at subnanomolar concentrations dramatically enhances the secretion of the α-secretase product sAPPα in fibroblasts from AD patients. We also show that BL significantly increased the amount of sAPPα and reduced Aβ40 in the brains of APP[V717I] transgenic mice. In a more recently developed AD double-transgenic mouse, bryostatin was effective in reducing both brain Aβ40 and Aβ42. In addition, bryostatin ameliorated the rate of premature death and improved behavioral outcomes. Collectively, these data corroborate PKC and its activation as a potentially important means of ameliorating AD pathophysiology and perhaps cognitive impairment, thus offering a promising target for drug development. Because bryostatin 1 is devoid of tumor-promoting activity and is undergoing numerous clinical studies for cancer treatment in humans, it might be readily tested in patients as a potential therapeutic agent for Alzheimer's disease.
Mpl Baltimore: A thrombopoietin receptor polymorphism associated with thrombocytosis
Authors: Moliterno Alison R. , Williams Donna M. , Gutierrez-Alamillo Laura I. , Salvatori Roberto , Ingersoll Roxann G. , Spivak Jerry L.
Published: July 2004

The chronic myeloproliferative disorders (MPD) are clonal hematopoietic stem cell disorders of unknown etiology. We have reported defective thrombopoietin receptor (Mpl) protein expression in MPD patients. To determine whether the basis of abnormal Mpl protein expression was due to mutations in the
Mpl
gene, we sequenced Mpl cDNA from MPD patients. We found a single nucleotide substitution (G1238T) that results in a change from lysine to asparagine at amino acid 39 (K39N) in three African-American women referred for an evaluation of an MPD. We subsequently screened more than 400 patients and controls and found that the K39N substitution is a polymorphism restricted to African Americans and that ≈7% of African Americans are heterozygous for K39N. African Americans with the K39N polymorphism had a significantly higher platelet count than controls without the polymorphism (
P
< 0.001) and reduced platelet protein Mpl expression. Expression of an Mpl cDNA containing the K39N substitution in cell lines was associated with incomplete processing and a reduction in Mpl protein, recapitulating the Mpl protein defect observed in platelets from individuals with K39N. K39N represents an identified functional
Mpl
polymorphism and is associated with altered protein expression of Mpl and a clinical phenotype of thrombocytosis.
Effects of group and situational factors on pre-adolescent children’s attitudes to school bullying
Authors: Nesdale Drew , Scarlett Michael
Published: July 2004

This study examined the effect on pre-adolescent children’s attitudes to bullying of one group-based variable (group status) and two situational variables (rule legitimacy and rule consistency). Pre-adolescent boys ( n 1/4 229) read a story about a group of boys who had high or low (handball) status. The legitimacy (high versus low) of the rules governing the use of a handball court, and the extent to which the group’s claim to the court was consistent with the rules (high versus low), were also manipulated. The participants’ liking, causal attribution, deservingness, and punishment responses to an intergroup bullying episode instigated by the group of boys against children from another class indicated that the participants recognised the import of the situational variables and, at least to some extent, took them into account. Nevertheless, the results indicated that the children favoured the bully group, and that their responses systematically reflected this bias. Possible bases for understanding these effects are discussed.
The Essential Role of PP1β inDrosophilaIs to Regulate Nonmuscle Myosin
Authors: Vereshchagina Natalia , Bennett Daimark , Szöőr Balázs , Kirchner Jasmin , Gross Sascha , Vissi Emese , White-Cooper Helen , Alphey Luke
Published: July 2004

Reversible phosphorylation of myosin regulatory light chain (MRLC) is a key regulatory mechanism controlling myosin activity and thus regulating the actin/myosin cytoskeleton. We show that Drosophila PP1β, a specific isoform of serine/threonine protein phosphatase 1 (PP1), regulates nonmuscle myosin and that this is the essential role of PP1β. Loss of PP1β leads to increased levels of phosphorylated nonmuscle MRLC (Sqh) and actin disorganisation; these phenotypes can be suppressed by reducing the amount of active myosin. Drosophila has two nonmuscle myosin targeting subunits, one of which (MYPT-75D) resembles MYPT3, binds specifically to PP1β, and activates PP1β's Sqh phosphatase activity. Expression of a mutant form of MYPT-75D that is unable to bind PP1 results in elevation of Sqh phosphorylation in vivo and leads to phenotypes that can also be suppressed by reducing the amount of active myosin. The similarity between fly and human PP1β and MYPT genes suggests this role may be conserved.
Gosha‐jinki‐gan (a Herbal Complex) Corrects Abnormal Insulin Signaling
Authors: Qin Bolin , Nagasaki Masaru , Ren Ming , Bajotto Gustavo , Oshida Yoshiharu , Sato Yuzo
Published: July 2004

Previous studies have shown that the traditional herbal complex Gosha‐jinki‐gan (GJG) improves diabetic neuropathy and insulin resistance. The present study was undertaken to elucidate the molecular mechanisms related with the long‐term effects of GJG administration on insulin action in vivo and the early steps of insulin signaling in skeletal muscle in streptozotocin (STZ) diabetes. Rats were randomized into five subgroups: (1) saline treated control, (2) GJG treated control, (3) 2‐unit insulin + saline treated diabetic, (4) saline + GJG treated diabetic and (5) 2‐unit insulin + GJG treated diabetic groups. After seven days of treatment, euglycemic clamp experiment at an insulin infusion rate of 6 mU/kg/min was performed in overnight fasted rats. Despite the 2‐unit insulin treatment, the metabolic clearance rates of glucose (MCR, ml/kg/min) in diabetic rats were significantly lower compared with the controls (11.4 ± 1.0 vs 44.1 ± 1.5; P < 0.001), and were significantly improved by insulin combined with GJG or GJG alone (26 ± 3.2 and 24.6 ± 2.2, P < 0.01, respectively). The increased insulin receptor (IR)‐β protein content in skeletal muscle of diabetic rats was not affected by insulin combined with GJG administration. However, the decreased insulin receptor substrate‐1 (IRS‐1) protein content was significantly improved by treatment with GJG. Additionally, the increased tyrosine phosphorylation levels of IR‐β and IRS‐1 were significantly inhibited in insulin combined with GJG treated diabetes. The present results suggest that the improvement of the impaired insulin sensitivity in STZ‐diabetic rats by administration of GJG may be due, at least in part, to correction in the abnormal early steps of insulin signaling in skeletal muscle.
Traditional and Modern Biomedical Prospecting: Part II—The Benefits
Authors: Müller Werner E. G. , Schröder Heinz C. , Wiens Matthias , Perovic-Ottstadt Sanja , Batel Renato , Müller Isabel M.
Published: July 2004

The progress in molecular and cell biology has enabled a rational exploitation of the natural resources of the secondary metabolites and biomaterials from sponges (phylum Porifera). It could be established that these natural substances are superior for biomedical application to those obtained by the traditional combinatorial chemical approach. It is now established that the basic structural and functional elements are highly conserved from sponges to the crown taxa within the Protostomia (Drosophila melanogaster and Caenorhabditis elegans) and Deuterostomia (human); therefore, it is obvious that the molecular etiology of diseases within the metazoan animals have a common basis. Hence, the major challenge for scientists studying natural product chemistry is to elucidate the target(s) of a given secondary metabolite, which is per se highly active and selective. After this step, the potential clinical application can be approached. The potential value of some selected secondary metabolites, all obtained from sponges and their associated microorganisms, is highlighted. Examples of compounds that are already in medical use (inhibition of tumor/virus growth [arabinofuranosyl cytosine and arabinofuranosyl adenine]), or are being considered as lead structures (acting as cytostatic and anti‐inflammatory secondary metabolites [avarol/avarone], causing induction of apoptosis [sorbicillactone]) or as prototypes for the interference with metabolic pathways common in organisms ranging from sponges to humans (modulation of pathways activated by fungal components [aeroplysinin], inhibition of angiogenesis [2‐methylthio‐1,4‐napthoquinone], immune modulating activity [FK506]) are discussed in this study. In addition, bioactive proteins from sponges are listed (antibacterial activity [pore‐forming protein and tachylectin]). Finally, it is outlined that the skeletal elements—the spicules—serve as blueprints for new biomaterials, especially those based on biosilica, which might be applied in biomedicine. These compounds and biomaterials have been isolated/studied by members of the German Center of Excellence BIOTECmarin. The goal for the future is to successfully introduce some of these compounds in the treatment of human diseases in order to raise the public awareness on the richness and diversity of natural products, which should be sustainably exploited for human benefit.
Green Light Stimulates Early Stem Elongation, Antagonizing Light-Mediated Growth Inhibition
Authors: Folta Kevin M.
Published: July 2004

During the transition from darkness to light, the rate of hypocotyl elongation is determined from the integration of light signals sensed through the phototropin, cryptochrome, and phytochrome signaling pathways. In all light conditions studied, from UV to far-red, early hypocotyl growth is rapidly and robustly suppressed within minutes of illumination in a manner dependent upon light quality and quantity. In this study, it is shown that green light (GL) irradiation leads to a rapid increase in the growth rate of etiolated Arabidopsis seedlings. GL-mediated growth promotion was detected in response to constant irradiation or a short, single pulse of light with a similar time course. The response has a threshold between 10−1 and 100  μmol m−2, is saturated before 102  μmol m−2 and obeys reciprocity. Genetic analyses indicate that the cryptochrome or phototropin photoreceptors do not participate in the response. The major phytochrome receptors influence the normal amplitude and timing of the GL response, yet the GL response is normal in seedlings grown for hours under constant dim-red light. Therefore, phytochrome activation enhances, but is not required for, the GL response. Seedlings grown under green, red, and blue light together are longer than those grown under red and blue alone. These data indicate that a novel GL-activated light sensor promotes early stem elongation that antagonizes growth inhibition.
Cloning and Characterization of Two NAD Kinases from Arabidopsis. Identification of a Calmodulin Binding Isoform
Authors: Turner William L. , Waller Jeffrey C. , Vanderbeld Barb , Snedden Wayne A.
Published: July 2004

NAD kinase (NADK; ATP:NAD 2′-phosphotransferase, EC 2.7.1.23), an enzyme found in both prokaryotes and eukaryotes, generates the important pyridine nucleotide NADP from substrates ATP and NAD. The role of NADKs in plants is poorly understood, and cDNAs encoding plant NADKs have not previously been described to our knowledge. We have cloned two cDNAs from Arabidopsis predicted to encode NADK isoforms, designated NADK1 and NADK2, respectively. Expressed as recombinant proteins in bacteria, both NADK1 and NADK2 were catalytically active, thereby confirming their identity as NADKs. Transcripts for both isoforms were detected in all tissues examined and throughout development. Although the predicted catalytic regions for NADK1 and NADK2 show sequence similarity to NADKs from other organisms, NADK2 possesses a large N-terminal extension that appears to be unique to plants. Using recombinant glutathione-S-transferase fusion proteins and calmodulin (CaM)-affinity chromatography, we delineated a Ca2+-dependent CaM-binding domain to a 45-residue region within the N-terminal extension of NADK2. Although recombinant NADK2 was not responsive to CaM in vitro, immunoblot analysis suggests that native NADK2 is a CaM-binding protein. In Arabidopsis crude extracts, CaM-dependent NADK activity was much greater than CaM-independent activity throughout development, particularly in young seedlings. A native CaM-dependent NADK was partially purified from Arabidopsis seedlings (K  m  NAD=0.20 mM, K  m  Mg2+−ATP=0.17 mM). The enzyme was fully activated by conserved CaM (S  0.5 = 2.2 nm) in the presence of calcium but displayed differential responsiveness to eight CaM-like Arabidopsis proteins. Possible roles for NADKs in plants are discussed in light of our observations.
Signal Peptide-Dependent Targeting of a Riceα-Amylase and Cargo Proteins to Plastids and Extracellular Compartments of Plant Cells
Authors: Chen Min-Huei , Huang Li-Fen , Li Hsou-min , Chen Yung-Reui , Yu Su-May
Published: July 2004

α-Amylases are important enzymes for starch degradation in plants. However, it has been a long-running debate as to whether α-amylases are localized in plastids where starch is stored. To study the subcellular localization of α-amylases in plant cells, a rice (Oryza sativa) α-amylase, αAmy3, with or without its own signal peptide (SP) was expressed in transgenic tobacco (Nicotiana tabacum) and analyzed. Loss-of-function analyses revealed that SP was required for targeting of αAmy3 to chloroplasts and/or amyloplasts and cell walls and/or extracellular compartments of leaves and suspension cells. SP was also required for in vitro transcribed and/or translated αAmy3 to be cotranslationally imported and processed in canine microsomes. αAmy3, present in chloroplasts of transgenic tobacco leaves, was processed to a product with M  r similar to αAmy3 minus its SP. Amino acid sequence analysis revealed that the SP of chloroplast localized αAmy3 was cleaved at a site only one amino acid preceding the predicted cleavage site. Function of the αAmy3 SP was further studied by gain-of-function analyses. β-Glucuronidase (GUS) and green fluorescence protein fused with or without the αAmy3 SP was expressed in transgenic tobacco or rice. The αAmy3 SP directed translocation of GUS and green fluorescence protein to chloroplasts and/or amyloplasts and cell walls in tobacco leaves and rice suspension cells. The SP of another rice α-amylase, αAmy8, similarly directed the dual localizations of GUS in transgenic tobacco leaves. This study is the first evidence of SP-dependent dual translocations of proteins to plastids and extracellular compartments, which provides new insights into the role of SP in protein targeting and the pathways of SP-dependent protein translocation in plants.
Critical Roles of Bacterioferritins in Iron Storage and Proliferation of Cyanobacteria
Authors: Keren Nir , Aurora Rajeev , Pakrasi Himadri B.
Published: July 2004

Cyanobacteria are key contributors to global photosynthetic productivity, and iron availability is essential for cyanobacterial proliferation. While iron is abundant in the earth's crust, its unique chemical properties render it a limiting factor for photoautotrophic growth. As compared to other nonphotosynthetic organisms, oxygenic photosynthetic organisms such as cyanobacteria, algae, and green plants need large amounts of iron to maintain functional PSI complexes in their photosynthetic apparatus. Ferritins and bacterioferritins are ubiquitously present iron-storage proteins. We have found that in the cyanobacterium Synechocystis sp. PCC 6803 (Synechocystis 6803), bacterioferritins are responsible for the storage of as much as 50% of cellular iron. Synechocystis 6803, as well as many other cyanobacterial species, have two bacterioferritins, BfrA and BfrB, in which either the heme binding or di-iron center ligating residues are absent. Purified bacterioferritin complex from Synechocystis 6803 has both BfrA and BfrB proteins. Targeted mutagenesis of each of the two bacterioferritin genes resulted in poor growth under iron-deprived conditions. Inactivation of both genes did not result in a more severe phenotype. These results support the presence of a heteromultimeric structure of Synechocystis bacterioferritin, in which one subunit ligates a di-iron center while the other accommodates heme binding. Notably, the reduced internal iron concentrations in the mutant cells resulted in a lower content of PSI. In addition, they triggered iron starvation responses even in the presence of normal levels of external iron, thus demonstrating a central role of bacterioferritins in iron homeostasis in these photosynthetic organisms.
Novel Biosynthetic Pathway of Castasterone from Cholesterol in Tomato
Authors: Kim Tae-Wuk , Chang Soo Chul , Lee June Seung , Takatsuto Suguru , Yokota Takao , Kim Seong-Ki
Published: July 2004

Endogenous brassinosteroids (BRs) in tomato (Lycopersicon esculentum) seedlings are known to be composed of C27- and C28-BRs. The biosynthetic pathways of C27-BRs were examined using a cell-free enzyme solution prepared from tomato seedlings that yielded the biosynthetic sequences cholesterol → cholestanol and 6-deoxo-28-norteasterone ↔ 6-deoxo-28-nor-3-dehydroteasterone ↔ 6-deoxo-28-nortyphasterol → 6-deoxo-28-norcastasterone → 28-norcastasterone (28-norCS). Arabidopsis CYP85A1 that was heterologously expressed in yeast mediated the conversion of 6-deoxo-28-norCS to 28-norCS. The same reaction was catalyzed by an enzyme solution from wild-type tomato but not by an extract derived from a tomato dwarf mutant with a defect in CYP85. Furthermore, exogenously applied 28-norCS restored the abnormal growth of the dwarf mutant. These findings indicate that the C-6 oxidation of 6-deoxo-28-norCS to 28-norCS in tomato seedlings is catalyzed by CYP85, just as in the conversion of 6-deoxoCS to CS. Additionally, the cell-free solution also catalyzed the C-24 methylation of 28-norCS to CS in the presence of NADPH and S-adenosylmethionine (SAM), a reaction that was clearly retarded in the absence of NADPH and SAM. Thus it seems that C27-BRs, in addition to C28-BRs, are important in the production of more active C28-BRs and CS, where a SAM-dependent sterol methyltransferase appears to biosynthetically connect C27-BRs to C28-BRs. Moreover, the tomato cell-free solution converted CS to 26-norCS and [2H6]CS to [2H3]28-norCS, suggesting that C-28 demethylation is an artifact due to an isotope effect. Although previous feeding experiments employing [2H6]CS suggested that 28-norCS was synthesized from CS in certain plant species, this is not supported in planta. Altogether, this study demonstrated for the first time, to our knowledge, that 28-norCS is not synthesized from CS but from cholesterol. In addition, CS and [2H6]CS were not converted into BL and [2H6]BL, respectively, confirming an earlier finding that the active BR in tomato seedlings is not BL but CS. In conclusion, the biosynthesis of 28-norBRs appears to play a physiologically important role in maintaining homeostatic levels of CS in tomato seedlings.
Strain Determination in Epitaxic Films of Materials of Orthorhombic Symmetry by High-Resolution X-ray Diffraction
Authors: Caro L. De , Tapfer L.
Published: July 2004

In this paper, we derive the most general expression of the X-ray incidence parameter. The new expression of the incidence parameter allows us to determine the lattice deformation of strained epitaxic films of materials of orthorhombic symmetry by high-resolution X-ray diffraction. The strain status of epilayers can be evaluated by using layer and substrate peaks of different reflections. In particular, the lattice mismatch (strain fields) between substrate and epilayers can be determined even if the heterostructure is made of materials of different crystallographic symmetry,e.g.high-Tcperov-skite superconductor thin films deposited on SrTiO3. In addition, the new expression of the incidence parameter takes into account the most general uniform lattice deformation of the epilayer crystal unit cell. Furthermore, it should be noted that the new expression is particularly useful if the angular separation Δθ between layer and substrate Bragg peaks is so large that the more conventional first- or second-order approximations in Δθ of the incidence parameter are not valid.
Cryocrystallography: effect of cooling medium on sample cooling rate
Authors: Walker Linda J. , Moreno Phillip O. , Hope Håkon
Published: July 2004

The rates of cooling of small samples with cold N2gas (100 K), liquid N2(77 K) and liquid propane (100 K) have been measured. The samples were one bare Cu-constantan thermocouple and one coated with a 0.25 mm layer of silicone rubber cement. Gas cooling yielded the lowest rate, liquid N2the highest. With the gas, cooling of the centers of the samples from 295 to 140 K took 0.8 and 2 s for the bare and coated samples, respectively; with liquid N2the times were 0.15 and 0.6 s, and with liquid propane they were 0.15–0.18 and 1.2 s, respectively (time reproducibility is within ±10%).
Structure Analysis of Intercalated Zirconium Phosphate Using Molecular Simulation
Authors: Čapková Pavla , Beneš Ludvi´k , Melánová Klára , Schenk Henk
Published: July 2004

Molecular simulation supported by X-ray diffraction and IR spectroscopy has been used to analyse the structure of α-zirconium phosphate intercalated by ethanol, Zr(HPO4)2.2C2H5OH. Molecular-mechanics simulations using theCrystal Packermodule in theCerius2modelling environment revealed the crystal packing in the interlayer,i.e.the positions of ethanol with respect to the Zr(HPO4)2layers and the layer stacking in the intercalated structure. The average interlayer distanced\,=\,14.03 (13) Å obtained by modelling is in agreement with the experimentaldvalue of 14.05 (4) Å obtained from the X-ray diffraction analysis. The disorder in the Zr(HPO4)2.2C2H5OH structure found by molecular simulation has been confirmed by the character of the X-ray diffraction pattern.
Patterson-oriented automatic structure determination. Organic structures
Authors: Pavelcik F.
Published: July 2004

Automatic Patterson methods combined with Fourier recycling have been applied to the determination of organic structures. Test calculations showed that these methods can be useful alternatives to traditional direct methods.
Axial Divergence in a Conventional X-ray Powder Diffractometer. II. Realization and Evaluation in a Fundamental-Parameter Profile Fitting Procedure
Authors: Cheary R. W. , Coelho A. A.
Published: July 2004

An accurate model for the axial divergence aberration function has been implemented within a fundamental-parameters fitting procedure for diffraction profiles from a conventional X-ray powder diffractometer. The aberration function for axial divergence is derived from the geometrical dimensions of the diffractometer in the axial plane and the angular apertures of any Soller slits in the beam path. This function is then convoluted with other instrument and specimen aberration functions to form the final profile shape. As this process only requires a modest amount of computational effort, it has been incorporated into both a fundamental-parameters profile-analysis fitting program and a Rietveld refinement program. In these programs, the refinable parameters for the axial divergence contribution to the profile shape are the axial X-ray source length, the sample length, the receiving-slit length and the aperture angles of the primary and secondary Soller slits. The procedure developed has been evaluated by fitting diffraction patterns collected using two different X-ray diffractometers and a variety of Soller slits and sample configurations to introduce varying degrees of axial divergence in the incident and diffracted beams. The reference materials used for this work included Y2O3, LaB6(SRM 660), Cr2O3(SRM 674a) and CeO2(SRM 674a). In all cases, the refined instrumental parameters defining the axial divergence were in good agreement with the directly measured values. Rietveld refinement using the present axial divergence model resulted inRwpvalues that are significantly lower than those based on currently available models for this aberration function.
Simultaneous Rheology and Small-Angle Scattering Experiments on Block Copolymer Gels and Melts in Cubic Phases
Authors: Hamley I. W. , Pople J. A. , Gleeson A. J. , Komanschek B. U. , Towns-Andrews E.
Published: July 2004

A new instrument for simultaneous small-angle X-ray scattering and rheology experiments on soft solids is described. This device is based on a commercial rheometer with a shear sandwich geometry in which the sample is subjected to a planar oscillatory deformation. This instrument has been used for time-resolved small-angle X-ray scattering/rheology experiments at the Synchrotron Radiation Source, Daresbury Laboratory, England. The focus has been in particular on the effect of large-amplitude shearing on the orientation of cubic phases in gels of block copolymers formed in concentrated solutions, and on the bicontinuous cubic phase of a block copolymer melt. Representative results are presented for face-centred cubic (f.c.c.) and body-centred cubic (b.c.c.) phases in gels of poly(oxyethylene)–poly(oxybutylene) diblock copolymers, and for the bicontinuous cubic `gyroid' structure in a poly-(ethylene-alt-propylene)–poly(dimethylsiloxane) di-block copolymer melt. The orientations of the micellar b.c.c. phases in the gels and the gyroid structure (belonging to the b.c.c. space group Ia\bar 3d) following large-amplitude shearing are shown to be the same,i.e.directionally oriented crystals are produced in both cases, in which (111) directions are oriented along the shear direction.
Simulation and Measurement of X-ray Diffraction from Single Crystals and Evaluation of Optimized Data Collection
Authors: Sarvestani A. , Walenta A. H. , Busetto E. , Lausi A. , Fourme R.
Published: July 2004

In the case of macromolecular crystallography, the measurement of diffracted intensities with monochromatic X-ray radiation is generally performed by the rotation method. A simulation program has been designed and tested by comparison with experimental data to investigate the various factors that are involved in the measurement and to improve collection strategies and tools, especially when using radiation from a third-generation synchrotron source. This program takes into account the main source and detector parameters in a realistic way, together with the possibility of selecting the sample characteristics. This then allows one both to evaluate the performances of existing experimental set-ups and to tailor the characteristics of new instruments,e.g.when designing a new detector or a new source.
A New Structural Model for Nongraphitic Carbons
Authors: Azuma Hideto
Published: July 2004

A structural analysis using a new, simple model describing the stacking structure of nongraphitic carbons is presented. The model is based on the idea that there is only a nearest-neighbour interaction between carbon layers. The nearest-neighbour interaction is described by the distribution of interlayer dist-ances, which, assuming a linear conjugate of two independent Gaussian distributions, gives a good fit to the obtained X-ray diffraction profile of carbon. This model is applied to a heat-treated series of nongraphitizing carbons from phenolic resin. The result shows that the average interlayer distances are about 0.4 nm. The model allows the diffraction intensity from carbon layers and the scattering intensity due to the porous structure of the carbon samples to be differentiated.
Calculation of Single-Crystal Elastic Constants for Cubic Crystal Symmetry from Powder Diffraction Data
Authors: Gnäupel-Herold Thomas , Brand Paul C. , Prask Henry J.
Published: July 2004

In this work a method is developed that allows the computation of the single-crystal elastic constants for crystals of cubic symmetry from the diffraction elastic constants. The diffraction elastic constants can be obtained by measuring thehkl-dependent lattice strain response to an applied stress. Because of theirhkldependence they represent, partially, the anisotropic nature of the single-crystal elastic constants. The computation of the single-crystal elastic constants is carried out by a least-squares refinement which fits the calculated diffraction elastic constants to the measured ones.
Energy requirements for palm‐kernel oil processing operations
Authors: Jekayinfa S.O. , Bamgboye A.I.
Published: July 2004

Direct energy utilization in nine palm‐kernel oil (PKO) mills located in Southwestern Nigeria was analyzed. The mills were stratified into small, medium and large‐scale categories, based on their modes of operations and production capacities. Evaluation of energy usage was carried out in the seven readily defined unit operations namely: palm‐nut drying, palm‐nut cracking, palm‐kernel roasting, palm‐kernel crushing, PKO expression, PKO sifting and PKO bottling/pumping. PKO extraction rates in the three mill categories were evaluated. The average PKO extraction rate for small, medium and large mills were 48.45 percent, 42.68 percent and 36.24 percent, respectively. The total energy expenditure in small, medium and large‐scale PKO mills were 350.89MJ/tonne, 230.70MJ/tonne and 181.74MJ/tonne, respectively. This suggests that the unit energy requirement for PKO output decreases as mill capacity increases. The four most highly energy‐intensive operations identified were palm‐nut cracking, palm‐kernel roasting, palm‐kernel crushing and PKO expression, altogether accounting for 95.29, 92.14 and 93.65 percent of total energy used in small, medium and large‐scale mills, respectively.
Household consumption of stock cubes and stock powder in the Vaal Triangle of SA
Authors: Chen Zhengxing , Oldewage‐Theron Wilna
Published: July 2004

This is the pilot study of a larger project in which fortification was evaluated in a clinical intervention trial in the Vaal Triangle of South Africa. The main purpose is to determine the suitability of stock cubes and stock powder as possible vehicles for fortification. A questionnaire was developed to determine stock cube and stock powder consumption patterns and handed out to the 802 subjects in the randomly selected sample, after testing for reliability. The results showed that 97 per cent of respondents (n=802) used stock cubes or powder daily in cooking, mainly stews, with the total consumption being 26 per cent chicken, 24 per cent beef, 15 per cent oxtail, 12 per cent mutton, 12 per cent tomato and 11 per cent vegetable. Stock cubes (79 per cent) were more popular than stock powder (21 per cent). From a consumption point of view, compared with other staple foods such as wheat flour, sugar and maize meal, stock cubes and/or stock powder are consumed on a daily basis by 97 per cent respondents and might thus be suitable vehicles for delivering micronutrients to many population groups without major changes in food production or changes in customary diets.
Dietary patterns of smokers and non‐smokers in the United Arab Emirates
Authors: Musaiger Abdulrahman O. , Abdulraoof Nadia
Published: July 2004

Data on 203 Emirati men were taken to study the differences among smokers, ex‐smokers and non‐smokers in food intake. Results revealed that there was no statistically significant association between smoking and frequency intake of some common foods. However, smokers were less likely to consume fruits and vegetables, and more likely to consume tea and fish than other groups. Intervention programmes to control smoking should take into consideration the dietary habits and lifestyle of smokers to reduce the risk of chronic diseases among them.
Memetic engineering: a framework for organisational diagnosis and development
Authors: Pech Richard , Slade Bret
Published: July 2004

This paper examines the concept of memetic engineering as a means of facilitating organisational diagnosis and development. It draws lessons for managers and organisational development specialists from current and topical examples of powerful organisational memes. Using a process of memetic mapping through the three elements of meme fidelity, host susceptibility, and level of resonance, managers may develop a heuristic for diagnosis of memes and their impact upon organisational culture and execution of the mission. Potentially, using this dual memetic engineering framework, managers may be able to calculate both the fitness and effect of the meme against existing and desired organisational culture and mission. It is argued that memetic engineering is a practical process for protecting the organisation from toxic memes and as a means of heightening awareness of potential threats in the cultural environment or the mindscape of the organisation.
Propagation of an alternative enterprise service application adoption model
Authors: Fulford Richard , Love Peter E.D.
Published: July 2004

The much‐heralded provision of enterprise resource planning (ERP) and customer relationship management (CRM) applications via hosting houses has been deemed to have failed. Many investigations have taken place, most of which have analysed the failure from the customer perspective, trying to understand why the end‐user did not endorse the application service provision (ASP) model. This paper examines the ASP value chain and identifies the winners and risk takers within it. The supply side of ASPs is analysed and an alternative model for ASP adoption propagated.