bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of fruit juice drinks in aseptic packages
Authors: Alves Rosa M. Vercelino , Sarantópoulos Claire I. G. L. , Saron Elisabete Segantini , Bordin Maurício R.
Published: September 2002

Cashew and passion fruit juice drinks were aseptically filled in cartons and in three types of plastic packages (with oxygen transmission rate‐OTR of 1,40; 2,96 and 13,74 cm3 (STP)/m2/day at 25 °C, 75% RH and 1 atm), with nitrogen gas flushing. No adverse effect on product sterility was found, neither were any significant changes in pH and acidity detected during storage at 25 ± 2°C. A decrease of the oxygen concentration in the headspace of the cashew juice drink plastic packs was observed, which appears to be caused by consumption of that gas in oxidation reactions. The shelf‐life of the cashew juice drink was limited to 45–70 days, after which period sensory changes attained objectionable levels (development of dark colours and deterioration of the typical fruit flavour). Passion fruit juice drink proved to be less sensitive to oxygen than cashew, since an increase of the oxygen concentration was detected in the headspace of the three plastic packs. The shelf‐life of passion fruit juice drink was limited to 70–90 days, due to deterioration of the typical passion fruit flavour and colour. Copyright © 2001 John Wiley & Sons, Ltd.
Ab initio study of reactions of hydroxyl radicals with chloro‐ and fluoro‐substituted methanes
Authors: El‐Taher S.
Published: September 2002

Ab initio calculations at the unrestricted Hartree–Fock (UHF) level have been performed to investigate the hydrogen abstraction reactions of ⋅OH radicals with methane and nine halogen‐substituted methanes (F, Cl). Geometry optimization and vibrational frequency calculations have been performed on all reactants, adducts, products, and transition states at the UHF/6‐31G* level. Single‐point energy calculations at the MP2/6‐31++G* level using the UHF/6‐31G* optimized geometries have also been carried out on all species. Pre‐ and postreaction adducts have been detected on the UHF/6‐31G* potential energy surfaces of the studied reactions. Energy barriers, ΔE‡, reaction energies, ΔEr, reaction enthalpies, ΔHr, and activation energies, Ea, have been determined for all reactions and corrected for zero‐point energy effects. Both Ea and ΔHr come into reasonable agreement with the experiment when correlation energy is taken into account and when more polarized and diffuse basis sets are used. The Ea values, estimated at the PMP2/6‐31++G* level, are found to be in good agreement with the experimental ones and correctly reproduce the experimentally observed trends in fluorine and chlorine substitution effects. A linear correlation between Ea and ΔHr is obtained, suggesting the presence of an Evans–Polanyi type of relationship. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 426–440, 2001
Accurate mass measurement of synthetic analogues of prazosine by matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry
Authors: Andalò Christian , Bocchini Paola , Pozzi Romina , Galletti Guido C.
Published: September 2002

Matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry (MALDI‐TOFMS) has been investigated as a tool for accurate determination of the molecular mass of synthetic analogues of prazosine, a molecule used for the treatment of hypertension. Samples were dissolved in methanol, mixed with mass calibration standards, and crystallised on the target with α‐cyano‐4‐hydroxycinnamic acid as matrix. Acquisition of spectra was rapidly completed in reflectron mode, allowing high resolution (6000–10000) and sensitive (about 1–10 pmol of sample on target) determination of the synthetic products. The results show the effectiveness of MALDI‐TOFMS for accurate mass determination of these fairly large molecules, which are otherwise difficult to analyse by other high‐resolution mass spectrometric techniques. Copyright © 2001 John Wiley & Sons, Ltd.
An experimental comparison of electrospray ion‐trap and matrix‐assisted laser desorption/ionization post‐source decay mass spectra for the characterization of small drug molecules
Authors: LeRiche Tammy , Osterodt Jens , Volmer Dietrich A.
Published: September 2002

An experimental comparison of product ion spectra produced by matrix‐assisted laser desorption/ionization (MALDI) and electrospray ion‐trap MS
n for a group of small drug molecules is presented in this paper. The goal of the study was to demonstrate the usefulness of MALDI‐MS with post‐source decay (PSD) and collision‐induced dissociation (CID) for the structural analysis of small drug molecules in the drug discovery process, where traditionally electrospray LC/MS methods are used. PSD and PSD/CID gave diverse product ions that were highly indicative of the structure of the drugs investigated (a group of 4‐quinolone antibiotics and oleandomycin). In addition, the number of different product ions generated with MALDI‐MS was always higher than with electrospray ion‐trap MS
n (with n ≤4) for the drug molecules studied. This investigation also showed that the choice of a suitable MALDI matrix for the analysis of low molecular weight compounds is quite important. It was found that of the three matrices examined, α‐cyano‐4‐hydroxycinnamic acid (α‐CHCA) produced the most intense fragmentation levels while TiO2, with its advantage of virtually no low mass background signals, did not generate quite the same amount of information. Copyright © 2001 John Wiley & Sons, Ltd.
The generalized Rice lognormal channel model—first and second order statistical characterization and simulation
Authors: Vatalaro F. , Mazzenga F. , De Maio G. , Forcella A.
Published: September 2002

The Rice‐lognormal (RLN) channel model was recently generalized to include an additive scattering component having constant average power. The generalized Rice‐lognormal (GRLN) model includes as limiting cases many well‐known narrowband models such as, e.g. Rice, lognormal (and combinations), and Loo's. The paper provides the GRLN first‐order statistical description of envelope and phase, and the second‐order statistics in terms of level crossing rate. The paper then provides a fitting procedure to extract model parameters from experimental data. Finally, it presents a new simulation procedure and validates it through comparison with theoretical results. Copyright © 2002 John Wiley & Sons, Ltd.
Structuring financial empowerment for localized development within Joint Forest Management (JFM): examples from Madhya Pradesh, India1
Authors: Sethi Pia , Khan Hilaluddin
Published: September 2002

Joint Forest Management (JFM) in India provides local communities with forest usufructs such as fuelwood, fodder, non‐timber forest produce and a share in the final timber harvest in lieu of their forest protection and regeneration activities. Such usufructs, alone, are unlikely to sustain interest in the JFM programme. Instead, village resource development activities may provide a potent mechanism for reducing dependence on forests, for enhancing participation in the JFM programme and for leading to improvements in people's livelihood status. Through case studies on the experiences with village development in the Indian state of Madhya Pradesh, this paper attempts to make a case for using JFM as a medium for localized development and for diversifying and encouraging fund sources for this purpose, particularly village common funds. Copyright © 2001 John Wiley & Sons, Ltd and ERP Environment.
Direct visualization of telomeric DNA loops in cells by AFM
Authors: Chen Ai , Cao En‐Hua , Sun Xue‐Guang , Qin Jing‐Fen , Liu Dage , Wang Chen , Bai Chun‐li
Published: September 2002

Telomeres are an essential nucleoprotein structure at the ends of all eukaryotic chromosomes. Studies on the structure and function of telomeres have received particular attention owing to their possible significance to ageing and cancer. In this work, human telomere from HeLa cells were isolated and purification by bio‐gel P‐2 column. Large duplex loops with a tail were first observed directly in the purified telomeric DNA species by atomic force microscopy (AFM). The lengths of the loop and tail are ∼2.5 ± 0.5 and 2.0 ± 1.5 kb, respectively. The AFM images also showed that the circular portion of loops is assumed to be a double‐stranded structure according to its apparent height, but to be a triplex or tetraplex structure for the loop–tail junction. These results indicate that telomeres in human cells may end in large loops, which is an advantage in further studies on the structure and function of telomeres in cells and provides a new procedure for the study of telomere structure. Copyright © 2001 John Wiley & Sons, Ltd.
Room‐temperature surface structure of 4‐aminobenzoic acid on Cu(110) surfaces
Authors: Chen Q. , Frankel D. J. , Richardson N. V.
Published: September 2002

The room‐temperature adsorption of 4‐aminobenzoic acid on a Cu(110) surface is studied with high‐resolution electron energy‐loss spectroscopy (HREELS), low‐energy electron diffraction (LEED), temperature‐programmed desorption and scanning tunnelling microscopy. Initially, the molecule adsorbs in a flat‐lying geometry and forms domains with a periodicity of (3 × 4)g. Increasing the coverage, the surface is saturated with this flat‐lying structure at a coverage of 0.167 ML. Further increasing the surface coverage, the HREEL spectrum shows some additional upright species without any change in LEED pattern. Scanning tunnelling microscopy shows that this upright species is present along domain boundaries that are preferentially aligned along the (3, ±4) directions. Copyright © 2001 John Wiley & Sons, Ltd.
In situ STM studies on underpotential deposition of Sn on Au(100)
Authors: Yan J. W. , Tang J. , Yang Y. Y. , Wu J. M. , Xie Z. X. , Sun S. G. , Mao B. W.
Published: September 2002

We present in situ STM studies on Sn electrodeposition on Au(100) surfaces at underpotentials. The Sn under potential deposition (UPD) on Au(100) proceeds in three stages: the reversible submonolayer UPD; surface alloying; and alloying that extends to the bulk. The formation of the reversible submonolayer UPD proceeds in the form of clusters of ∼2 nm at potentials as early as 0.04 V. The surface alloying takes place at −0.04 V, which is evidenced by sudden immersion of the Sn clusters as well as significant changes of steps on the surface. The bulk alloying sets in at −0.3 V, which leads to rapid change of the surface morphology. The earlier set in of the surface and bulk alloying process is considered the result of enhanced interdiffusion of Sn and Au atoms upon decreasing the potential. It has been shown that Sn UPD on Au(100) is much more complex than that of other metal UPD systems studied previously by electrochemical scanning tunnelling microscopy, but it serves as a good system for all‐sided studies of the UPD processes. Copyright © 2001 John Wiley & Sons, Ltd.
Characteristics of Au/Ti/p‐diamond ohmic contacts prepared by r.f. sputtering
Authors: Zhen Congmian , Liu Xueqin , Yan Zhijun , Gong Hengxiang , Wang Yinyue
Published: September 2002

Low‐resistance ohmic contacts were fabricated on diamond films by boron ion implantation and subsequent Ti/Au bilayer metallization. The I–V measurements showed that the as‐deposited contacts were ohmic. After annealing at 500 °C for 10 min in a vacuum of 10−4Pa, the I–V characteristics were improved significantly. As a result of annealing, the specific contact resistance (ρC) value, measured by the circular transmission line model (CTLM), decreased from 6.2 × 10−3 to 1.2 × 10−6 Ω·cm2. Compared with the value calculated by the transmission line model (TLM), the ρC value was reduced by more than two orders of magnitude for the annealed contacts. The CTLM should be more accurate in measurement than the TLM. The changes of the ρC value with the operating temperature indicated that the ρC value decreased with increasing operating temperature at low temperatures. Tunnelling was suggested to be the dominant transport mechanism at the metal/diamond interface. The band model was quantified. Copyright © 2001 John Wiley & Sons, Ltd.
Influence of sulphonation on polymer and polymer blend surfaces studied by atomic force microscopy
Authors: Berlinger A. , Gliemann H. , Barczewski M. , Durigon P. E. R. , Siqueira Petri D. F. , Schimmel Th.
Published: September 2002

Films of immiscible blends of polystyrene (PS) and poly(methyl methacrylate) (PMMA) on silicon wafers were prepared by spin‐coating and subsequently modified by sulphonation with sulfuric acid. The weight ratios of the polymer blends were 1 : 3 and 3 : 1. The increase of the PS fraction combined with chemical treatment of the blends with sulfuric acid results in an increase in surface wettability by water. This correlation can be understood by investigating the influence of these parameters on the surface of the polymer blends by atomic force microscopy. To determine the distribution of PS and PMMA within the polymer blends we used cyclohexane and acetic acid as selective solvents for PS and PMMA, respectively, and compared the coating topography before and after treatment with the solvents. Copyright © 2001 John Wiley & Sons, Ltd.
Plasma modification of PTFE surfaces. Part II: Plasma‐treated surfaces following storage in air or PBS
Authors: Wilson D. J. , Williams R. L. , Pond R. C.
Published: September 2002

The mechanisms and kinetics of the ageing process of polytetrafluoroethylene (PTFE) samples stored in either phosphate‐buffered saline (PBS) or air for periods of up to 1 month have been investigated. Changes of surface chemistry and wettability were studied as a function of ageing time using the complementary techniques of x‐ray photoelectron spectroscopy, static secondary ion mass spectroscopy and dynamic contact angle measurements. Specimens were aged either in the as‐received condition or after treatment by O2, Ar, N2 and NH3 plasma as described in Part I. Evidence was obtained for two ageing mechanisms, namely chemical reaction with the storage medium and relaxation in the surface region of the polymer. The extent of these mechanisms depended on the initial plasma treatment and the nature of the storage medium. These issues are discussed in a framework that correlates wettability with surface chemistry in a semiquantitative manner. This analysis facilitates comparison of the changes induced on virgin material by plasma treatment and ageing in storage environments relevant to the biomedical application of PTFE. Copyright © 2001 John Wiley & Sons, Ltd.
ToF‐SIMS and XPS study of photoactivatable reagents designed for surface glycoengineering. Part III. 5‐Carboxamidopentyl‐N‐[m‐[3‐(trifluoromethyl)diazirin‐3‐yl]phenyl‐β‐D‐galactopyranosyl]‐(1‐>4)‐1‐thio‐β‐D‐glucopyranoside (lactose aryl diazirine) on diamond
Authors: Léonard D. , Chevolot Y. , Heger F. , Martins J. , Crout D. H. G. , Sigrist H. , Mathieu H. J.
Published: September 2002

Time‐of‐flight Secondary Ion Mass Spectrometry (ToF‐SIMS) and x‐ray photoelectron spectroscopy (XPS) are used to characterize a newly synthesized glycosylated photoactivatable reagent designed for surface glycoengineering. The immobilization on diamond surfaces of the glycoaryldiazirine reagent lactose aryl diazirine (5‐carboxamidopentyl‐N‐[m‐[3‐(trifluoromethyl)diazirin‐3‐yl]phenyl‐β‐D‐galactopyranosyl]‐(1‐>4)‐1‐thio‐β‐D‐glucopyranoside) is compared to a previously studied monoglycosylated photoactivatable reagent (MAD‐Gal). The XPS atomic constituents and chemical shifts, as well as ToF‐SIMS specific characteristic fragments and molecular peaks of the new photoimmobilized molecule are recorded. Spectral differences are identified in XPS C 1s spectra and in the high mass range of positive ion ToF‐SIMS spectra for the surface immobilized disaccharide. The ToF‐SIMS characteristic high‐mass ions involve both cationization with Na+ and loss of the diazirine function. The results can be related to differences observed in biological assays with each of the surface immobilized saccharides. Copyright © 2001 John Wiley & Sons, Ltd.
Surface‐related investigations to characterize different preparation techniques of Sb‐doped SnO2 powders
Authors: Szczuko D. , Werner J. , Behr G. , Oswald S. , Wetzig K.
Published: September 2002

Antimony‐doped tin oxide powders were prepared using different routes and annealing conditions. The influence of preparation on the distribution of antimony in the powders was studied and correlated with the electrical properties of the powders. A model of doped SnO2 powder that allows the bulk concentration of the doping element to be calculated from the XPS results is proposed. The doping after crystallization of SnO2 leads to a very strong surface segregation that is proved by x‐ray photoelectron spectroscopy. Antimony is incorporated at the largest concentration in the tin oxide lattice when it is added during the formation of stannic acid. The annealing temperature plays an important role in the antimony distribution. The lower the temperature, the smaller the crystallite size and the lower the incorporation of antimony in the lattice of SnO2. A strong correlation between bulk concentration and electrical and morphological properties was found. Copyright © 2001 John Wiley & Sons, Ltd.
Comment on ‘AES and SAM microanalysis of structure ceramics by thinning and coating the backside. Yu and Jin’
Authors: Paparazzo E.
Published: September 2002

A paper by Yu and Jin (Surf. Interface Anal. 2001; 31: 338) describing Auger microanalysis of ceramic insulating materials is commented upon. The major criticism regards the authors' claim that reliable scanning Auger microscopy (SAM) analysis can be performed on the (Y,La)‐doped α‐Si3N4 sample when this is made thinner by dimpling and Ar+ ion etching, two procedures that prevent surface charging phenomena. In fact, this comment shows that: Ar+ ion bombardment produces insurgence of Si–Si bonding states as a result of chemical reduction of surface SixNyOz species, so that no chemical‐state information actually can be derived from the Si LVV and Si KLL spectra of this sample because the layers probed by Auger analysis are not very reminiscent of the genuine chemical composition of this material; and SAM imaging results obtained from the same material are heavily affected by topographical artefacts and no reliable information thus can be derived from its true microchemical surface lateral heterogeneity.

It is suggested that the use of reflected electron energy‐loss microscopy, i.e. a technique that is in itself immune to surface charging phenomena, would have been likely to assist better than SAM in the microchemical characterization of insulating materials. Copyright © 2001 John Wiley & Sons, Ltd.
Reply to “Comment on ‘AES and SAM microanalysis of structure ceramics by thinning and coating the backside. Yu and Jin’”
Authors: Yu Ling , Jin Deling
Published: September 2002

The comments by Paparazzo1 on our paper2 raise some interesting points that certainly deserve further comment. In the discussion below we address the two substantive points raised by Paparazzo and show that, in our opinion, our methodology is a valid approach to the type of analysis in question. Copyright © 2001 John Wiley & Sons, Ltd.
Reproducibility in r.f.‐GDOES depth profiling analysis of thin films
Authors: Shimizu K. , Habazaki H. , Skeldon P. , Thompson G. E.
Published: September 2002

The reproducibility in radiofrequency glow discharge optical emission spectroscopy (r.f.‐GDOES) depth profiling has been examined using a 360 nm thick anodic alumina film with a chromium‐containing delta‐function layer. The time required to sputter through the film was constant, to within 1%, whereas the signal intensities of film species agreed to within 3%. This level of reproducibility together with high depth resolution makes the technique ideal for on‐site quality control of various surface‐enhanced industrial products, embracing electronics and protective surface treatments. Copyright © 2001 John Wiley & Sons, Ltd.
Effect of rapid thermal annealing on the electrical properties of ion‐beam‐synthesized oxide layers using 12 keV O2+ bombardment of Si
Authors: Deenapanray Prakash N. K.
Published: September 2002

Surface layers of SiO2 were synthesized by bombarding n‐type Si samples with 12 keV O2+ ions at 10° incidence in a SIMS instrument. The oxide layers were annealed at 950 °C for 3, 6 or 8.5 min under Ar flow in a rapid thermal annealer. Temperature‐dependent current–voltage (I–V–T) measurements were used in order to establish both the dielectric quality and the current transport mechanisms across the dielectric layers. Annealing for 8.5 min doubled the breakdown voltage while decreasing the leakage current by a factor of ∼18. The ohmic quality of the layers for the low field strengths decreased with the increasing annealing time, which is related to the removal of implantation damage as observed by high‐resolution RBS measurements. For the high field strengths, the tunnelling effect was most dominant for the oxide annealed for 8.5 min. The breakdown voltage of oxide layers exhibited an Arrhenius‐like dependence on the sample temperature, with the activation energy for breakdown decreasing with the increasing annealing time. Deep‐level transient spectroscopy (DLTS) and capacitance–voltage (C–V) measurements also were used to characterize the samples. Copyright © 2001 John Wiley & Sons, Ltd.
AES quantification of intergranular film thickness in the Ni–Bi system with respect to the liquid metal embrittlement phenomenon
Authors: Wolski K. , Marié N. , Biscondi M.
Published: September 2002

Intergranular penetration of liquid bismuth‐rich alloy in solid polycrystalline nickel is investigated at 700° C. Short intergranular films of micrometric thickness with a very acute tip are observed by SEM. Intergranular penetration of Bi–Ni alloy induces strong intergranular brittleness that extends far ahead of the micrometric film tip. Very long intergranular films of nanometric thickness are identified by AES after in situ intergranular fracture. A quantitative model aimed at the determination of the actual thickness of these films is developed and described in detail. The measured bismuth/nickel intensity ratios (IBi/INi) are correlated to the thickness of the intergranular film. Detailed procedures related to the determination of the experimental IBi/INi ratio as well as all assumptions related to the quantification model are clearly stated. Atomic densities, attenuation lengths and retrodiffusion factors are calculated whereas effective cross‐sections, probabilities of de‐excitation by the Auger process and the transmission efficiency of the analyser are suppressed from the final formulae due to reference measurements on the bulk Bi–Ni embrittling alloy, which is used as a bicomponent standard of known composition. Numerical application gives a value of 2–4 nm for the thickness of the film formed during 8 h at 700° C. The uncertainty mainly comes from the difficulty in determination of the Auger electron collection angle, due to the use of polycrystals. Interest for the use of bicrystals is underlined. It is postulated that the mechanisms of liquid metal embrittlement (LME) should be analysed with respect to the tip of this nanometric film. Copyright © 2001 John Wiley & Sons, Ltd.
Auger electron appearance potential spectroscopy study of CrNx films
Authors: Chourasia A. R. , Hood S. J.
Published: September 2002

Thin films of chromium nitride deposited with varying concentrations of nitrogen on stainless steel substrates have been studied using Auger electron appearance potential spectroscopy (AEAPS). This technique provides information on the density of states in the conduction band. The chromium L2,3 levels have been investigated. The normalized AEAPS chromium spectra in the films have been compared with the elemental chromium spectrum. The signal strength at the Fermi level (EF) is observed to be larger in the films. This represents an increase in the density of states at EF for the films as compared with that of elemental chromium. However, in the films, the density of states is found to decrease with increasing nitrogen concentration. The binding energy of the chromium L3 level for the films exhibits a positive chemical shift with respect to elemental chromium. These spectral data indicate a direction of charge transfer from chromium to nitrogen. In the films, the charge transfer is observed to decrease with increasing nitrogen content. We also present a scheme to estimate the Coulomb correlation energy using the chromium L3 core‐level binding energy data obtained from AEAPS and x‐ray photoelectron spectroscopy (XPS). A decrease in the correlation energy with increasing nitrogen content is observed for the films. We also have estimated the total density of unoccupied states above EF from the experimental data. This total density is observed to be more in the films than in elemental chromium. In the films, the total density of states decreases with nitrogen concentration. The AEAPS spectral results have been correlated with our earlier XPS results on these films. Copyright © 2001 John Wiley & Sons, Ltd.
Diabetes teratogenicity in mice is accompanied with distorted expression of TGF‐β2 in the uterus
Authors: Fein A. , Magid N. , Savion S. , Orenstein H. , Shepshelovich J. , Ornoy A. , Torchinsky A. , Toder V.
Published: September 2002

Early embryonic deaths as well as malformed newborns are among complications of the diabetic pregnancy. Cytokines and growth factors operating in the embryonic vicinity are found to be among factors that determine the sensitivity of embryos to external and internal detrimental stimuli, including diabetes. Transforming Growth Factor‐β2 (TGF‐β2) has been shown to be essential for embryonic development and survival. In the present work, we evaluated the pattern of TGF‐β2 expression in the uterus of streptozotocin‐induced diabetic mice, demonstrating a decreased reproductive performance and elevated percentage of litters with severely malformed fetuses. Since stimulation of the maternal immune system was found to increase the resistance of mouse embryos to the teratogenic effect of diabetes, the effect of immunopotentiation on the expression of the cytokine was also investigated. TGF‐β2 expression was studied at the mRNA level by using the in situ hybridization technique and at the protein level by using the immunohistochemical analysis. A clear decrease in TGF‐β2 mRNA expression in the uterus of diabetic mice was observed at examined time points: days 1, 5, and 9 of pregnancy. Also, an evident reduction in TGF‐β2, the protein expression in the uterus of diabetic mice, was demonstrated at these time points. Maternal immunopotentiation that improved the reproductive performance of diabetic mice and reduced the number of the litters with malformed fetuses was also accompanied by a clear increase in the level of TGF‐β2 mRNA expression in the pregnant uteri. The above results clearly demonstrate that the embryotoxic effect of diabetes is accompanied by an alteration of TGF‐β2 expression. Immunopotentiation that was shown to improve the reproductive performance of the diabetic mice was accompanied by a partial normalization of TGF‐β2 expression in embryonic vicinity. Teratogenesis Carcinog. Mutagen. 22:59–71, 2002. © 2002 Wiley‐Liss, Inc.
The role of radicals in enzymatic processes
Authors: Frey Perry A.
Published: September 2002

Research on the mechanism of action of coenzyme B12, adenosylcobalamin, as a graduate student introduced the author to the field of organic free radicals in enzymology. Twenty years later, related work on S‐adenosylmethionine (SAM) as a “poor man’s coenzyme B12” was initiated in a detailed analysis of the mechanism of action of lysine 2,3‐aminomutase (LAM). The interconversion of l‐lysine and l‐β‐lysine is catalyzed by LAM, which requires SAM, pyridoxal‐5′‐phosphate (PLP), and a [4Fe–4S] cluster as coenzymes. The mechanism of this reaction has been delineated as a radical isomerization, in which radical formation is initiated by the [4Fe–4S]‐dependent cleavage of the SAM into methionine and the 5′‐deoxyadenosyl radical. The mechanism of this process is discussed, together with the role of this radical in hydrogen abstraction from lysine to initiate the substrate radical isomerization. The chemistry underlying the functions of SAM, PLP, and [4Fe–4S] in the action of LAM is novel in all respects, except for the formation of a lysine‐PLP aldimine at the active site. Of the four free radicals in the mechanism, three have been characterized by EPR spectroscopy. In the suicide inactivation of adenosylcobalamin‐dependent dioldehydrase (DDH) by glycolaldehyde, the formation of cob(II)alamin and 5′‐deoxyadenosine is accompanied by the conversion of glycolaldehyde to cis‐ethanesemidione radical at the active site. The cis‐ethanesemidione radical has been characterized by EPR spectroscopy. Its exceptional stability at the active site is the basis for the inactivation of DDH by glycolaldehyde. © 2001 John Wiley & Sons, Inc. and The Japan Chemical Journal Forum Chem Rec 1:277–289, 2001
Selection bias in Teratology Information Service pregnancy outcome studies
Authors: Johnson K. A. , Weber P. A. , Jones K. L. , Chambers C. D.
Published: September 2002

Background

Pregnancy outcome studies conducted through Teratology Information Services (TIS) rely on volunteer subjects. If these subjects tend to have different risk profiles than the population from which they are drawn, the results of TIS studies may have limited generalizability.

Methods

We selected all subjects who enrolled in the California Teratogen Information Service (CTIS) pregnancy outcome study for prenatal exposure to carbamazepine or valproic acid between 1990 and 1997 and who received prenatal care through Kaiser Permanente of Southern California (n = 13). We compared these subjects to Kaiser patients identified through the Maternal Serum Alpha Fetoprotein Program with exposure to carbamazepine or valproic acid but who had not enrolled in the CTIS project. The controls were matched by Kaiser location and pregnancy year using a 2:1 ratio (n = 26). Medical records were reviewed and the prevalence of 14 pregnancy risk factors was compared between the two groups.

Results

There were no significant differences between the groups on any one risk factor; however, a notably higher proportion of women who did not enroll in the CTIS study used tobacco or had a positive family history of congenital anomalies.

Conclusions

Although the sample was small, and results may not apply to other exposures in different health care environments, these data provide some evidence that women who enroll in TIS pregnancy outcome studies do not have a substantially different pregnancy risk profile than women who do not. Efforts to address possible selection bias should be incorporated in future TIS study design. Teratology 64:79–82, 2001. © 2001 Wiley‐Liss, Inc.
Predatory behavior of the snake Bothrops jararaca and its adaptation to captivity
Authors: Troncone Lanfranco R.P. , Silveira Paulo F.
Published: September 2002

Habituation to captivity is difficult for some species. Understanding the motivational elements involved in predation may ease this habituation. Seventy‐one Brazilian jararaca snakes (Bothrops jararaca [Wied, 1824], Viperidae, Crotalinae) recently captured and never fed in captivity were tested for predatory behavior on rodents. Lighting was adapted to allow predatory sessions to occur during the first hours of the night when these animals are more active. Up to three prey subjects were presented in a session. In the first experiment, the preference for prey size and color was assessed using albino and dark‐colored rodents. In a second experiment, a group of snakes was submitted to 12 sessions during a period of almost 2 years. The strike strategy was classified in one of two categories: envenomation (E) or seizing (S). Envenomation involved a bite delivered by the snake with prompt retrieval of the head; holding the rodent in the snake’s jaws since the first strike, without retrieving the fangs and holding the prey during venom action, characterized S strike. Trailing and swallowing the dead prey always followed E strike. Results suggest that snakes fed more often on larger subjects. The color of the prey was not a relevant factor. E strike was predominant in the first predatory event in captivity. After habituation, S strike was predominant. Snakes may have a poor perception of the prey objects in captivity and adopt a strike strategy that assures the control of the prey. Also, the use of small prey subjects to ease feeding during adaptation to captivity may be less effective. Zoo Biol 20:399–406, 2001. © 2001 Wiley‐Liss, Inc.
Efficacy of levonorgestrel when administered as an irradiated, slow‐release injectable matrix for feline contraception
Authors: Looper Sheri , Anderson Gary , Sun Yichun , Shukla Atul , Lasley Bill
Published: September 2002

Reliable and safe methods of reversible contraception are needed for use in zoo felids. The efficacy of levonorgestrel (LNG) as a contraceptive, when delivered as a cesium‐irradiated, slow‐release, injectable matrix, was tested in domestic cats as a model for exotic cats. An increase (P= 0.0017) in body weight was observed in treated but not control queens (P= 0.2146). All control queens (n = 6), which received injections of matrix only, but none of the LNG‐treated queens (n = 6) became pregnant during the trial. Levonorgestrel was effective in preventing pregnancy for at least 36 weeks after two injections of drug‐loaded formulations (40 mg/kg body weight), administered 68 days apart. Throughout the study, all control queens displayed luteal activity and fluctuating fecal estradiol concentrations, whereas the LNG‐treated queens displayed lower estradiol concentrations and no luteal activity after treatment. We conclude that LNG, when delivered as a cesium‐irradiated, slow‐release, injectable matrix, is an effective contraceptive in domestic cats, reducing follicular activity, and thus, preventing mating and luteal activity. Zoo Biol 20:407–421, 2001. © 2001 Wiley‐Liss, Inc.
Influence of group size and neonatal handling on growth rates, survival, and tameness of juvenile houbara bustards
Authors: van Heezik Yolanda , Seddon Philip J.
Published: September 2002

The influence of group size, sex, year, and environmental enrichment on growth of a large sample of captive‐bred houbara bustards was examined, as well as the influence of regular handling on survival. Growth rates of chicks kept in groups of eight were depressed compared with chicks in groups of five. Differences in growth rates between males and females were not significant at fledging (∼35 days), but were so by 80 days, although interindividual variation still precluded reliable sexing by body mass at this age. Growth rates varied between years, suggesting that management practices may affect growth, and potentially the reproductive performance of birds. Survival of birds receiving extra handling, mainly in the form of regular weighing, was significantly higher than that of birds receiving little handling. The effect of environmental enrichment on tameness was also assessed. Tameness is desirable in the captive flock, where stress is perceived as a major impediment to reproductive performance, preventing the successful collection of semen from males and insemination of females, delaying recruitment, and causing nonbreeding among both sexes. Extra handling and environmental enrichment was applied to a sample of chicks, and tameness of juveniles was assessed in a variety of ways (open field test, subjective assessments), but no significant difference was found between the enriched birds and a control group. The enrichment protocol might be improved by increasing the period of time during which birds were handled and associating handling with food rewards, although the time required to carry out such a protocol may be constrained when large numbers of chicks are produced. Zoo Biol 20:423–433, 2001. © 2001 Wiley‐Liss, Inc.
Nociceptor activation and protein extravasation induced by inflammatory mediators in human skin
Authors: Lischetzki Grischa , Rukwied Roman , Handwerker Hermann O. , Schmelz Martin
Published: September 2002

Protein extravasation (PE) is known to play an important role in inflammatory conditions. In this study we used dermal microdialysis to apply inflammatory mediators (histamine, bradykinin, serotonin) to human skin. Locally induced PE was compared to pain ratings and axon reflex erythema measured simultaneously. Linear microdialysis capillaries (outer diameter 0.4 mm; cut‐off 3000 kDa) were inserted intracutaneously at a length of 1.5 cm in the volar forearm of healthy volunteers. The capillaries were perfused with Ringer's solution at a constant flow rate of 4 μ l/min. The perfusate was sampled at 15‐min intervals and was analysed for total protein concentration. After a baseline of 60 min, the perfusion was switched to inflammatory mediators for 30 min and then back to vehicle again. Sensations evoked by the stimulation were assessed on a visual analogue scale and visible axon reflex erythema was measured planimetrically.

Dose‐dependent increases in PE could be assessed for all inflammatory mediators tested. Bradykinin (10–7M) induced a significant PE, whereas serotonin was effective only at a concentration of 10–3M. While serotonin in lower concentrations induced moderate burning pain and an axon reflex flare but no PE, bradykinin provoked PE without pain or axon reflex flare at a concentration of 10–7M. Application of histamine similarly evoked PE at lower concentrations as compared to the induction of itch sensation and axon reflex flare.

It is concluded that there is no link between nociceptor activation and protein extravasation induced by inflammatory mediators in healthy human skin.
Outcome of surgery for cervical radiculopathy evaluated by determination of trapezius muscle microcirculation and electromyography
Authors: Löfgren Håkan , Larsson Romy , Larsson Sven‐Erik
Published: September 2002

Surgery for cervical radiculopathy was evaluated in 27 patients after anterior Cloward procedure (19 patients) or posterior decompression (eight patients). In addition, we examined 10 conservatively treated patients. Each patient was studied prospectively with regards to the effects on microcirculation in the local trapezius muscle during a fatiguing series of stepwise increased contractions. The right and left muscles were simultaneously examined pre‐operatively and postoperatively after 9 months using laser‐Doppler flowmetry and simultaneous surface electromyography (EMG). Preoperatively, a reduced microcirculation was found in the most painful side compared with the opposite side. This is in accordance with earlier reports on patients with chronic neurogenic neck pain, who also show reduced muscle tension on EMG. Postoperatively, the muscle blood flow became increased, but only in patients operated on via a posterior approach. A tendency at increased EMG‐amplitude and reduced mean power frequency of the EMG was noted. These EMG signs of muscle fatigue suggest increased ability to exhaust the trapezius muscle postoperatively. The observed postoperative changes were consistently more frequent in the less painful side. We conclude from these objective measurements showing only a tendency at increased microcirculation and muscle tension postoperatively, that the effect on the trapezius muscle is limited.
Energy saving by means of innovative building envelope systems
Authors: Meroni Italo , De Salvia Alba , Lollini Roberto , Pollastro M. Cristina
Published: September 2002

Nowadays, one of the main goals of the building industry and architecture is to exploit the solar source for the air‐conditioning of buildings. Over the last years many activities have started to develop new building and plant technologies oriented to energy saving by improving indoor comfort and reducing pollution emission. The guidelines deriving from various world conferences (Kyoto 1997, Buenos Aires 1998) are known. Industrial countries have committed themselves to try and carry out new strategies to reduce both energy consumption and air‐pollution. These aims have increased research works oriented to find materials, components and systems able to use energy gains from the environment, in particular from the sun. During the study carried out at ITC on the subject, two envelope technologies have been studied and realised. The paper describes such technologies and the methods used for their characterisation. It also reports on the most meaningful results obtained from the experiments carried out.
DEVELOPING CHAOS ON BASE OF TRAVELING WAVES IN A CHAIN OF COUPLED OSCILLATORS WITH PERIOD-DOUBLING: SYNCHRONIZATION AND HIERARCHY OF MULTISTABILITY FORMATION
Authors: SHABUNIN A. , ASTAKHOV V. , ANISHCHENKO V.
Published: September 2002

The work is devoted to the analysis of dynamics of traveling waves in a chain of self-oscillators with period-doubling route to chaos. As a model we use a ring of Chua's circuits symmetrically coupled via a resistor. We consider how complicated are temporal regimes with parameters changing influences on spatial structures in the chain. We demonstrate that spatial periodicity exists until transition to chaos through period-doubling and tori birth bifurcations of regular regimes. Temporal quasi-periodicity does not induce spatial quasi-periodicity in the ring. After transition to chaos exact spatial periodicity is changed by the spatial periodicity in the average. The periodic spatial structures in the chain are connected with synchronization of oscillations. For quantity researching of the synchronization we propose a measure of chaotic synchronization based on the coherence function and investigate the dependence of the level of synchronization on the strength of coupling and on the chaos developing in the system. We demonstrate that the spatial periodic structure is completely destroyed as a consequence of loss of coherence of oscillations on base frequencies.
Photo-oxygenation of meso-Tetraphenylporphyrin Derivatives: the Influence of the Substitution Pattern and Characterization of the Reaction Products
Authors: SILVA A. M. S. , NEVES M. G. P. M. S. , MARTINS R. R. L. , CAVALEIRO J. A. S. , BOSCHI T. , TAGLIATESTA P.
Published: September 2002

The photo-oxidation reactions of several meso-tetraphenylporphyrins have been studied in order to ascertain the chemical stability of this class of compounds towards singlet oxygen. The 2,6-disubstituted ones showed an excellent stability, whilst this is not the case for other porphyrins with different substitution pattern on the phenyl rings. This parallels what has been previously found using mono-oxygenated donors. The steric effects in protecting the macrocycle seems to be predominant over the electronic ones; even with electron-donating groups in the 2,6-positions, e.g. methoxy groups, the porphyrin macrocycle was not degraded. The reaction on the β-tetrabrominated meso-tetraphenylporphyrin also proceeded easily and yielded a bilinone derivative. The structures of the final products were all elucidated by mass, 1 H and 13 C NMR spectroscopy.
Bactericidal Activities of Radical Species Generated by Catalytic Reaction of Iron(III) Octacarboxyphthalocyanine
Authors: ICHINOHE TAKASHI , MIYAJIMA MAKOTO , NOGUCHI YASUHISA , ITO MASAHIKO , KIMURA MUTSUMI , KOYAMA TOSHIKI , HANABUSA KENJI , HACHIMORI AKIRA , SHIRAI HIROFUSA
Published: September 2002

Strong bactericidal activities against various bacteria were observed in the reaction system of iron(III) octacarboxyphthalocyanine ( Fe III - oapc ) and tert-butyl hydroperoxide (tert-BuOOH). The kinetics of the decomposition of tert-BuOOH catalysed by Fe III -oapc were studied in buffered solutions between pH 5 to 12 using gas chromatography analysis. The rate of catalytic decomposition of tert-BuOOH followed second-order kinetics in tert-BuOOH concentrations. The second-order rate constant (k2) had a maximum value at pH 11. Oxygen evolution was observed at high tert-BuOOH concentration, while oxygen consumption was observed at low tert-BuOOH concentration. The former indicates plural radical chain reactions of the tert-butoxyl radical and the latter suggests decomposition of the tert-butoxyl radical to acetone and methyl radical. By the electron spin resonance spin trapping method using 5,5-dimethyl-1-pyrroline-N-oxide and α-phenyl-N-tert-butylnitrone it was found that the radical species generated in the reaction system is tert-butoxyl radical, which plays crucial roles in bactericidal activities.
Energy Transfer in a Supramolecular Complex Assembled via Sapphyrin Dimer-mediated Dicarboxylate Anion Chelation
Authors: SPRINGS STACY L. , ANDRIEVSKY ANDREI , KRÁL VLADINÍR , SESSLER JONATHAN L.
Published: September 2002

The synthesis of a new terephthalate-strapped porphyrin is described. This porphyrin, prepared in the form of the free base and corresponding zinc(II) complex, was designed to act as the photo-donor portion of a novel, non-covalent artificial light-harvesting complex, the other, acceptor component of which is comprised of a covalently linked sapphyrin dimer. UV-vis and 1 H NMR spectroscopic analyses were used to establish that strong complexes are formed between the porphyrin terephthalate and sapphyrin dimer components (affinity constants on the order of 105 M−1 in dichloromethane). In these complexes the dicarboxylate portion of the strapped porphyrin is sandwiched between two sapphyrins of an individual dimer. Steady state fluorescence studies of the resulting ensembles support the conclusion that, upon photoexcitation of the porphyrin subunit, energy transfer from the porphyrin to the sapphyrin dimer occurs efficiently. This intra-ensemble, anion-chelation-based energy transfer can be inhibited by the addition of fluoride anion.
Comparative Photodynamic Therapy of B16 Pigmented Melanoma with Different Generations of Sensitizers
Authors: PEEVA M. , SHOPOVA M. , STOICHKOVA N. , MICHAILOV N. , WÖHRLE D. , MÜLLER S.
Published: September 2002

In order to apply photodynamic therapy to pigmented neoplasms, comparative photosensitizing studies of B 16 pigmented melanoma in C 57 B 1/6 mice were carried out with haematoporphyrin derivative (HpD), zinc(II) phthalocyanine ( ZnPc ), zinc(II) naphthalocyanine ( ZnNc ) and tetrabenzamido-substituted zinc(II) naphthalocyanine ( ZnNcA ). By injection of the optimal drug concentration and application of the optimal dose of light irradiation (the emission of the laser dye corresponding to the λmax value of the respective sensitizer) a phototherapeutic effect was observed only after photosensitization with the longest-wavelength-absorbing sensitizer, namely ZnNcA . It is supposed that the detected, through different assessment criteria, promising phototherapeutic effect after ZnNcA photosensitization of B 16 pigmented melanoma in mice is due to suitable structural, photophysical and photochemical properties of this sensitizer, but not due to a hyperthermic effect. This assumption is supported by the results obtained after irradiation of B 16 pigmented melanoma-bearing mice with the same fluence rate and fluence but without the sensitizer. In this case the tumour temperature did not increase by more than 35 °C and no changes in the mean tumour diameter or in the malignant subcellular components were detected.
Approaches to the synthesis of triphenylmethyl-phthalo-cyanines and their analogues
Authors: ISLYAIKIN M. K. , KUDRIK E. V. , YELKIN I. A.
Published: September 2002

The synthetic pathways to obtain 4-triphenylmethylphthalodinitrile, complexes of tetra (4-triphenylmethyl)phthalocyanine with copper, nickel and cobalt, and di(4-triphenylmethyl)triazolehemiporphyrazine are described.