bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ortho Effects in Quantitative Structure Activity Relationships for Lipase Inhibition by Aryl Carbamates
Authors: Lin Gialih , Liu Yue‐Chen , Wu Yon‐Gi , Lee Yu‐Ru 
Published: December 2003

AbstractOrtho‐substituted phenyl‐N‐butyl carbamates (1–11) are synthesized and evaluated for their inhibition effects on Pseudomonas species lipase. Carbamates 1–11 are characterized as pseudo‐substrate inhibitors of the enzyme. The logarithms of dissociation constant (Ki), carbamylation constant (k2), and bimolecular inhibition constant (ki) multiply linearly correlate with Hammett substituent constant (σ), Taft‐Kutter‐Hansch ortho steric constant (ES), and Swan‐Lupton field constant (F). For −logKi‐, logk2‐, and logki‐correlations, values of ϱ, δ, f, ρXR are 0.2, −0.06, −1.7, 0.8; 0.0, 0.0, 1.0, −0.07; and −1.8, 7, 0.6, 5; respectively. The enzyme inhibition mechanism is composed of four steps: 1) the first step which is protonation of carbamates 1–11, 2) the second step (Ki1) which involves in the proton 1,3‐shift of protonated carbamates 1–11 then the pseudo‐trans to cis conformational change, 3) the third step (Ki2) which is formation of a negative charged enzyme‐inhibitor tetrahedral intermediate, and 4) the fourth step (k2) which is the carbamylation step. The former three steps are likely composed of the Ki step. There is little ortho steric enhancement effect in the Ki step. From cross‐interaction correlations, distance between carbamate and phenyl substituents in transition state for the Ki step is relatively short due to a large ρXR value of 7. The k2 step is insensitive to ortho steric effect. The k2 step involves in departure of leaving group, substituted phenol in which is protonated from the proton 1,3‐shift but not from the active site histidine of the enzyme. From cross‐interaction correlations, the distance between carbamate and phenyl substituents in transition state for the k2 step is relatively long due to a small ρXR value of 0.6.
DFT Based Atomic Softness and Its Application in Site Selectivity
Authors: Singh P. P. , Pasha F. A. , Srivastava H. K. 
Published: December 2003

AbstractActive site of a complex molecule and mechanism of chemical reaction has been studied with the help of atomic softness values derived from calculation based on Density functional theory. The quantum mechanical equation of Klopman has been solved with the help of AM1 calculation by using Win MOPAC7.21 software. On the basis of chemical potential equalization principle, and Koopmans theorem for frontier orbitals a formalism has been developed for the calculation of electron affinity of an atom in a molecule EA. The reliability of the EA values have been tested with electron density (obtained from AM1 calculation) and Fukui function values taken from literature.
Artemisinin Derivatives with Antimalarial Activity against Plasmodium falciparum Designed with the Aid of Quantum Chemical and Partial Least Squares Methods
Authors: Pinheiro José C. , Kiralj Rudolf , Ferreira Márcia M. C. , Romero Oscar A. S. 
Published: December 2003

AbstractArtemisinin derivatives with antimalarial activity against Plasmodium falciparum resistant to mefloquine are designed with the aid of Quantum Chemical and Partial Least Squares Methods. The PLS model with three principal components explaining 89.55% of total variance, Q2=0.83 and R2=0.92 was obtained for 14/5 molecules in the training/external validation set. The most important descriptors for the design of the model were one level above the lowest unoccupied molecular orbital energy (LUMO+1), atomic charges in atoms C9 and C11 (Q9) and (Q11) respectively, the maximum number of hydrogen atoms that might make contact with heme (NH) and RDF030 m (a radial distribution function centered at 3.0 Å interatomic distance and weighted by atomic masses). From a set of ten proposed artemisinin derivatives, a new compound (26), was predicted with antimalarial activity higher than the compounds reported in literature. Molecular graphics and modeling supported the PLS results and revealed heme‐ligand and protein‐ligand stereoelectronic relationships as important for antimalarial activity. The most active 26 and 29 in the prediction set possess substituents at C9 able to extend to hemoglobin exterior, what determines the high activity of these compounds.
Effect of aluminium content on the coating structure and dross formation in the hot‐dip galvanizing process
Authors: Shawki Saher , Hamid Z. Abdel 
Published: December 2003

AbstractHot dipping of steel in aluminium–zinc baths of varying composition (5–90% Al) has been undertaken with the aim of elucidating the mechanism of coating formation. On the basis of these experiments, it has been possible to define a range of aluminium content over which there is a change from a normal galvanizing process to a typical aluminizing process. Alternatively, the coating structure and properties were markedly affected by the aluminium content of the dipping bath. The kinetics of such coatings acquires the character of the activation energy Ea. The effect of various silicon levels as an inhibitor to iron dissolution during hot dipping at different aluminium percentages was studied. The structure of dross formation in 55 wt.% Al–Zn was identified. The adverse effect of heavy accumulation of dross in the dipping pot on the coating structure also was shown. Copyright © 2003 John Wiley & Sons, Ltd.
Influence of substrate morphology on the cohesion and adhesion of thin PECVD oxide films on semi‐crystalline polymers
Authors: Rochat G. , Delachaux A. , Leterrier Y. , Månson J.‐A. E. , Fayet P. 
Published: December 2003

AbstractThe influence of the surface morphology of semi‐crystalline poly(ethylene terephthalate) (PET) and polyamide 12 (PA12) films on the adhesion and cohesion of thin oxide coatings is analysed, with attention paid to the role of spherulites and processing additives. The failure mechanisms of the coating are determined by means of fragmentation tests and the results are modelled using a constant interfacial strength approach with a Weibull‐type probability of fracture. Coating failure is shown to be initiated at defect sites such as pinholes and, in the case of PET, the presence of additives in the superficial layers of the polymer leads to a decrease of the crack onset strain by a factor of 20%. Large spherulitic structures found at the surface of PA12 films are shown to lead to preferential delamination at spherulites boundaries. For the two types of semi‐crystalline polymers, the interfacial shear strength is found to be comparable to the bulk shear strength of the polymer. Copyright © 2003 John Wiley & Sons, Ltd.
Parametric analysis of the extraction of depth profile information from ARXPS data obtained on a silicon wafer sample
Authors: Paynter R. W. , Nolet D. 
Published: December 2003

AbstractIn this study a silicon wafer was analysed by angle‐resolved x‐ray photoelectron spectroscopy and the data compared with a calculation based upon a simple model of the sample surface. The parameters in the mathematical model were varied in groups of three and the sum‐squared difference between the calculation and the experimental results was plotted as an error surface. Most of the error surfaces were found to exhibit a well‐constrained minimum, indicating an optimum set of values for the parameters in question, but important examples of co‐dependency were also noted. Copyright © 2003 John Wiley & Sons, Ltd.
Determination of amount of substance for nanometre‐thin deposits: consistency between XPS, RBS and XRF quantification
Authors: Martin‐Concepción A. I. , Yubero F. , Espinos J. P. , Garcia‐Lopez J. , Tougaard S. 
Published: December 2003

AbstractQuantification on the nanometre scale is a key task in quality control and for the development of new materials in nanotechnology. In this paper we have studied the consistency in the determination of the amount of substance found by XPS peak shape analysis, Rutherford backscattering spectroscopy (RBS) and x‐ray fluorescence spectrometry (XRF). To this end, ZnO was deposited by plasma‐enhanced chemical vapour deposition on the three substrates. Four different sets of samples were produced, with the amount of ZnO deposited in the range 1–10 nm. From XPS analysis it is found that ZnO grows in the form of islands on all three substrates. For each system, the analysis was done independently with two XPS peaks from the overlayer with widely different kinetic energy and one XPS peak from the substrate. The growth mechanism found from analysis of each of the three peaks was consistent and the total amount of determined ZnO material was identical to within 15%. The root‐mean‐square deviation from the XPS quantification of the relative AOS was 20% for XRF and 16% for RBS. Because the absolute amount of substance determined from analysis of the three XPS peaks for each sample was consistent, it is concluded that the energy dependence of the applied inelastic mean free paths (taken here from the empirical TPP‐2M formula) is correct. It was found that the absolute amounts of substance determined by RBS and XRF are consistently factors of 2.1 and 1.5 lower than the that determined by XPS peak shape analysis. It is suggested that the main reason for this large discrepancy is inaccuracy in the applied ‘effective’ inelastic electron mean free path. Copyright © 2003 John Wiley & Sons, Ltd.
Structure of Cooked Spaghetti of Durum and Bread Wheats
Authors: Heneen Waheeb K. , Brismar Kerstin 
Published: December 2003

AbstractThe structure of cooked spaghetti of durum and bread wheats was studied using low voltage scanning electron microscopy, and light microscopy applying different staining methods. Central, intermediate and external regions, and four zones along the external region of cooked spaghetti strands, were characterized in unprecedented detail. Changes in structure of starch granules from core to surface portrayed the successive stages in starch gelatinization, and possible starch retrogradation in the external region. Pronounced changes in shape of starch granules commenced in the intermediate region, while apparent internal changes dominated in the external region. Spaghetti of bread wheats differed from that of durum wheats by the larger size and higher extent of fusions and retrogradation of starch, and less amounts and continuity of intervening proteins. The significance of a high protein concentration for pasta production from bread wheats was emphasized. Furthermore, the relevance of a small size of the large starch granules was inferred.
Phase and Gelation Behavior of 2‐Hydroxy‐3‐(N, N‐dimethyl‐N‐dodecylammonium)propyloxy Starches
Authors: Jonhed Anna , Järnström Lars 
Published: December 2003

AbstractSome starches containing quaternary dimethylalkylammonium groups exhibit an unique phase behavior. A solid phase or gel phase is formed upon cooling, i.e. they are temperature‐responsive polymers. The aim of this study was to investigate the phase and gelation behavior of hydrophobically modified quaternary ammonium starch ethers in aqueous solutions. The mechanisms behind the phase behavior and hydrophobic character were investigated by light scattering (turbidity) and rheological measurements. A relatively large increase in the complex viscosity at higher concentrations was observed when the solutions were cooled to room temperature. The phase angle decreased drastically at a certain critical temperature. The decrease in the phase angle depended on the concentration of starch in solution, higher concentrations showing the greatest decrease and lower concentrations showing no significant change. Turbidity measurements indicated that a solid‐like highly concentrated phase was precipitated. The starch with zero net charge showed a larger increase in turbidity than the starch with a positive net charge, which indicates that particular precipitation is favored by a zero net charge and that the formation of a gel network is favored by charged starch molecules.
Resistant Starch and Health — Himalaya 292, a Novel Barley Cultivar to Deliver Benefits to Consumers
Authors: Topping David L. , Morell Matthew K. , King Roger A. , Li Zhongyi , Bird Anthony R. , Noakes Manny 
Published: December 2003

AbstractDietary and lifestyle change is a recognised strategy for the management and prevention of socio‐economically important non‐infectious diseases. Dietary fibre is composed largely of non‐starch polysaccharides (NSP), and greater consumption of NSP‐rich foods relieves simple constipation very effectively. Starch (as resistant starch, RS) is also receiving attention for its potential role in promoting colonic function. Resistant starch is that fraction of starch which escapes human small intestinal digestion and enters the large bowel where (together with a variable fraction of NSP) it is fermented by the resident microflora. The resulting short chain fatty acids (SCFA) are taken up by the large bowel and metabolised. SCFA mediate many of the health benefits ascribed to NSP and RS. Starch consumption is low in affluent westernised countries, despite recommendations by health agencies. In Australia, foods enriched in RS as a high amylose maize starch have gained consumer acceptance. However, scope remains for additional products and ingredients and a company, Ascentia Pty Ltd, has been established to develop a novel barley cultivar (Hordeum vulgare var. himalaya 292) for this purpose. This cultivar has a specific gene alteration leading to a loss of starch synthetase lla activity resulting in a grain which is low in starch but disproportionately higher in amylose and also NSP. Animal and human studies have shown that Himalaya 292 is high in RS relative to existing products and has a low glycaemic index and the cultivar offers promise as a vehicle to deliver health benefits to consumers.
Pain and PTSD symptoms in female veterans⋆,⋆⋆
Authors: Asmundson Gordon J.G , Wright Kristi D , Stein Murray B 
Published: December 2003

AbstractBackground: There has been growing empirical examination of the co‐occurrence of pain and post‐traumatic stress disorder (PTSD) symptoms, and existing evidence suggests that the symptoms associated with each have a close association. To date, however, the association has only been examined within samples of mostly male participants.Aim: In the present study, pain and PTSD symptoms were examined in a sample of 221 female veterans who utilised the VA Healthcare System between 1998 and 1999.Method: Women who visited the clinic between 1998 and 1999 were mailed a self‐report questionnaire package designed to elicit information regarding general health (including pain experiences), military and trauma history, childhood abuse and neglect, and PTSD symptoms. Analyses were conducted to identify differences in pain experience between those women classified as having PTSD, subsyndromal PTSD, and no PTSD. Analyses were also conducted to determine the degree to which pain‐related (e.g., current pain, interference with activity) variables predicted PTSD symptom cluster scores.Results: The three groups differed significantly on a number of pain‐related variables. Analyses suggested that pain‐related variables were significant predictors of PTSD symptom cluster scores.Conclusions: These results indicate that the association between pain and PTSD symptoms, previously observed in primarily male samples, is generalisable to females. Clinical implications and possible mechanisms of association are discussed.
Electroconvulsive therapy in patients with depression and fibromyalgia
Authors: Huuhka Martti J , Haanpää Maija L , Leinonen Esa V.J 
Published: December 2003

AbstractThe effect of electroconvulsive therapy (ECT) on depression and other symptoms of fibromyalgia was studied in a prospective 3‐month trial in 13 patients with fibromyalgia and concomitant depression. All the patients met the DSM‐IV diagnostic criteria for Major Depressive Disorder and fulfilled the American College of Rheumatology diagnostic criteria for fibromyalgia. The Montgomery and Åsberg Depression Rating Scale (MADRS) and the clinical global impression scale (CGI) were used to assess the severity of depression and the clinical change of the patients. The fibromyalgia impact questionnaire (FIQ) was used to evaluate the severity of the fibromyalgia symptoms. The intensity of pain was evaluated using a 6‐point scale (0=no pain, 5=very severe pain), and tender point palpation. All assessments were performed at baseline and at follow‐up visits, which took place one week, one month and three months after ECT. There was a significant improvement in depression after ECT according to MADRS. Using CGI, six patients were much or very much improved, while four patients were minimally improved and three patients had no change. There was significant improvement in four out of ten FIQ item scores, “feel good”, “fatigue”, “anxiety” and “depression”. No significant change was found in the FIQ item scores “physical function”, “pain”, “stiffness” and “morning tiredness” or number of tender points and self‐reported pain. We conclude that ECT is a safe and effective treatment for depression in fibromyalgia patients, but has no effect on the pain or other physical symptoms of these patients.
Low back pain, disability and back pain myths in a community sample: prevalence and interrelationships
Authors: Goubert Liesbet , Crombez Geert , De Bourdeaudhuij Ilse 
Published: December 2003

AbstractThis study investigated the prevalence of back pain, disability, and, of most importance, the presence of misconceptions about low back pain (LBP), its diagnosis and treatment in a bicultural community sample (Belgium). Using the Graded Chronic Pain Scale [Pain 50 (1992) 133] persons were classified according to pain intensity and disability in five subgroups. The interrelationship between LBP beliefs and these five subgroups was also investigated. In our sample (n=1624) the 6‐month prevalence of low back pain was 41.8%. Only in 8.2% back pain was disabling. Misconceptions about back pain were widespread, even in the group reporting no back pain. The least misconceptions were found to exist in participants with mild LBP without disability. It is suggested that recovery from an episode of acute low back pain is an active process that involves a correction of beliefs about harm, about the need to restrict physical activities and about medical diagnosis and cure. Finally, it is argued that community actions may be useful to correct LBP myths in order to prevent the development of long‐term disability due to LBP.
Connexin 43 expression in glial cells of developing rhombomeres of Xenopus laevis
Authors: Katbamna Bharti , Jelaso Anna M. , Ide Charles F. 
Published: December 2003

AbstractConnexin 43 is a gap junctional protein found predominantly in astrocytes. In the mammalian nervous system, it appears to play an organizational role during neural development. In the current study, conducted on the frog, Xenopus laevis, we found that connexin 43 occurs in glial cells during development of rhombomeres and that its expression is spatially and temporally regulated. We used neural (2G9) and cell proliferation (BrdU) markers to identify the overall organization of Xenopus rhombomeres and then tracked expression of connexin 43 and glial fibrillary acidic protein, an intermediate filament protein known to mark glia during rhombomeric development. 2G9 was expressed in rhombomeric centers (ventricular concavities) and outlying neuropil regions, whereas BrdU‐labeled cells marked boundary regions (ventricular convexities), as early as stage 35/36. These labeling patterns persisted through premetamorphic stages of hindbrain development. At stage 47, 2G9‐labeled profiles were highlighted by the presence of connexin 43, and at stage 49/50, connexin 43‐labeled profiles, i.e., rhombomeric centers and neuropil, as well as rhombomeric boundaries, not labeled by connexin 43, became immunoreactive to glial fibrillary acidic protein. Cells of rhombomeric center regions and their processes in the outlying neuropil co‐expressed glial fibrillary acidic protein and connexin 43 at a time that is characterized by the emergence of hindbrain auditory neural circuitry. Glial fibrillary acidic protein positive glial cells that appeared at rhombomeric boundaries never expressed connexin 43, but rather appeared to physically bisect ventricular convexities into adjacent rhombomeric regions. Thus, glial cells that express connexin 43 in developing rhombomeric centers may be similar to radial glia, assisting in formation of neural circuitry, while glial cells that do not express connexin 43, situated at rhombomeric boundaries, may be involved in demarcating adjacent rhombomeres.
Development of a polar morphology by identified embryonic motoneurons
Authors: Whitington Paul M. , Sink Helen 
Published: December 2003

AbstractMotoneuron morphology arises through the coordinated growth of the motor axon and dendrites. In the Drosophila embryo the RP motoneurons have a contralaterally‐extended motor axon, ipsilateral dendrites that extend a short distance in the ipsilateral connective, and a tuft of short dendrites in the contralateral connective. In the present study mechanical and genetic manipulations were utilized to test if (i) the ipsilateral dendrites can develop an axon morphology, (ii) the presence of the contralateral motor axon suppresses the development of an axon‐like morphology by the ipsilateral dendrites and (iii) whether establishment of a contralateral motor axon can be genetically suppressed. It was found that an ipsilateral motor axon could develop—but only at the expense of the contralateral motor axon. Axotomy could overturn the normal polarity of the RP motoneurons in favor of the development of an ipsilateral motor axon, and this reversed morphology was also observed when the motor axon could not extend across the midline in the commissureless mutant. These findings show that the RP motoneurons have the plasticity for an alternative polarity, but that the extension of an ipsilateral axon is normally suppressed by the presence of the contralateral axon. The RP motoneurons now represent a genetically amenable in vivo system for analyzing the basis of polarity formation in neurons.
Mosquito repellent (pyrethroid‐based) induced dysfunction of blood–brain barrier permeability in developing brain
Authors: Sinha C. , Agrawal A.K. , Islam F. , Seth K. , Chaturvedi R.K. , Shukla S. , Seth P.K. 
Published: December 2003

AbstractPyrethroid‐based mosquito repellents (MR) are commonly used to protect humans against mosquito vector. New born babies and children are often exposed to pyrethroids for long periods by the use of liquid vaporizers. Occupational and experimental studies indicate that pyrethroids can cause clinical, biochemical and neurological changes, and that exposure to pyrethroids during organogenesis and early developmental period is especially harmful. The neurotoxicity caused by MR has aroused concern among public regarding their use.In the present study, the effect of exposure of rat pups during early developmental stages to a pyrethroid‐based MR (allethrin, 3.6% w/v, 8 h per day through inhalation) on blood–brain barrier (BBB) permeability was investigated. Sodium fluororescein (SF) and Evan's blue (EB) were used as micromolecular and macromolecular tracers, respectively. Exposure during prenatal (gestation days 1–20), postnatal (PND1–30) and perinatal (gestation days 1–20+PND1–30) periods showed significant increase in the brain uptake index (BUI) of SF by 54% (P<0.01), 70% (P<0.001), 79% (P<0.001), respectively. This increase persisted (68%, P<0.01) even 1 week after withdrawal of exposure (as assessed on PND37). EB did not exhibit significant change in BBB permeability in any of the group. The results suggest that MR inhalation during early prenatal/postnatal/perinatal life may have adverse effects on infants leading to central nervous system (CNS) abnormalities, if a mechanism operates in humans similar to that in rat pups.