bluuebunny/crossref_metadata_2025 huggingface dataset:
Exact Fixed‐node Quantum Monte Carlo: Differential Approach
Authors: Huang Hong‐Xin
Published: November 2005

A differential approach for exact fixed‐node quantum Monte Carlo calculation was proposed in this paper. This new algorithm can be used to directly compute the energy differential between two systems in exact fixed‐node quantum Monte Carlo process, making the statistical error of calculation reduce to order of 10−2 kJ/mol and recover about more than 90% of the correlation energy. The approach was employed to set up a potential energy surface of a molecule, through a model of rigid move, and Jacobi transformation utilized to make energy calculation for two configurations of a molecule having good positive correlation. So, an accurate energy differential could be obtained, and the potential energy surface with good quality depicted. This novel algorithm was used to study the potential energy curve of the ground state of BH and the potential energy surface of H3, and could be also applied to study other related fields such as molecular spectroscopy and the energy variation of chemical reactions.
Heat Capacity and Thermodynamic Properties of Crystalline 2‐Chloro‐N,N‐dimethylnicotinamide
Authors: Sun Xiao‐Hong , Liu Yuan‐Fa , Tan Zhi‐Cheng , Ji Peng‐Ju , Wang Mei‐Han
Published: November 2005

Low‐temperature heat capacities of 2‐chloro‐N,N‐dimethylnicotinamide were precisely measured with a high‐precision automated adiabatic calorimeter over the temperature range from 82 K to 380 K. The compoundwas observed to melt at (342.15±0.04) K. The molar enthalpy ΔfusionHm, and entropy of fusion, ΔfusionSm, as well as the chemical purity of the compound were determined to be (21387±7) J·mol−1, (62.51±0.01) J·mol−1·K−1, (0.9946±0.0005) mass fraction, respectively. The extrapolated melting temperature for the pure compound obtained from fractional melting experiments was (342.25±0.024) K. The thermodynamic function data relative to the reference temperature 298.15 K were calculated based on the heat capacity measurements in the temperature range from 82 to 325 K. The thermal behavior of the compound was also investigated by different scanning calorimetry.
Synthesis of Novel Binuclear Samarium Thiolate Complexes [(THF)3I2Sm(μ‐SAr)]2 (Ar=Ph, 4‐Me2NC6H4) and Crystal Structure of [(THF) 3I2Sm(μ‐S‐4‐Me2NC6H4)]2
Authors: Li Hong‐Xi , Zhang Yong , Ren Zhi‐Gang , Cheng Mei‐Ling , Wang Jing , Lang Jian‐Ping
Published: November 2005

Reactions of SmI2 in THF with ArSSAr produced two binuclear samarium thiolate complexes [(THF)3I2‐ Sm(μ‐SAr)]2 [Ar=Ph (1), 4‐Me2NC6H4 (2)] in high yields. The structure of 2 was characterized by single crystal X‐ray crystallography. The crystal of 2 belongs to the triclinic system with space group $ P {\bar 1} $ and a=0.95705(13) nm, b=1.22287(14) nm, c=1.26450(14) nm, α=64.194(11)°, B=78.491(13)°, γ=76.176(12)°, V=1.2860(3) nm3, Z=1, μ=4.783 mm−1, Dc=1.964 Mg/m3, M=1521.19, S=1.046, R1=0.0358, wR2=0.0910. X‐ray analysis revealed that 2 is a thiolate‐bridged dimer in which each Sm atom adopts a distorted pentagonal bipyramidal coordination geometry.
Theoretical Study on Efficiency of Anti‐explosion and Fireproof Agents
Authors: Huang Chao , Yang Xu‐Jie , Lu Lu‐De , Wang Xin
Published: November 2005

Multi‐protection is a principle in security management, and the use of anti‐explosion and fireproof agents is a crucial part of it. In this paper, the properties of nano‐oxide particles in the field of anti‐explosion and fireproof were analyzed. The sedimentation velocity of nanometer particles was calculated. CH4 was taken as an example, and its combustion mechanism of the initial stages was concluded. The effects of 15 oxides on molecular energies of the reaction system were calculated with program Hyperchem 6, and the possible contact manner between radicals and oxides was got. It was concluded that oxides, such as ZrO2, could combine with radicals, and thus prevent the combustion reaction. It was found that the nano‐ZrO2 eruptively generated aerosol is superior to other counterparts in serving as the anti‐explosion and fireproof agent, and therefore, will play an increasingly important role in the security management.
An Efficient Enantioselective Synthesis of Blastmycinone
Authors: Yang Yong‐Qing , Wu Yi‐Kang
Published: November 2005

Blastmycinone, a degradation product of the antibiotic antimycin A, was synthesized with a TiCl4‐mediated asymmetric aldolization as the key step. Some unexpected yet interesting chemistry was also observed.
Seven New Sesquiterpene Lactones from Eupatorium chinense
Authors: Yang Sheng‐Ping , Cheng Jia‐Gao , Huo Jun , Jiang Hua‐Liang , Chen Kai‐Xian , Yue Jian‐Min
Published: November 2005

Seven new sesquiterpenoids, namely eupatochinilides I–VII (1–7), together with eight known compounds, euponin (8), mollisorin A (9), niveusin B (10), 8β‐(4′,‐acetoxy‐tiglyloxy)‐3β ‐hydroxy‐6Hβ,7Hα‐germacra‐1(10)E,4E,11(13)‐trien‐6,12‐olide (11), eupalinilide B (12), 8β‐(4′‐hydroxytigloyloxy)‐5‐desoxy‐8‐desacyleuparotin (13), 3‐deacetyeupalinin A (14), and 15‐hydroxyleptocarpin (15), were isolated from the ethanolic extract of the whole plant of Eupatorium chinense L. Their structures and stereochemistry were established by spectroscopic methods and GIAO based 13C NMR chemical shift calculations.
An Insight of S‐Nitrosylation of Human GIF
Authors: Teng Xin‐Chen , Zheng Qi , Cai Bin , Ni Feng‐Yun , Xie Yi , Sun Hong‐Zhe , Zhang Ming‐Jie , Huang Zhong‐Xian
Published: November 2005

Neural growth inhibitory factor (GIF), a member of metallothionein family (metallothionein‐3, MT3), was well known by its distinct neural growth inhibitory activity, which is not shown by other MT isoforms. However, till now, people still did not know clearly how GIF exerts its biological functions. Since it has been reported that GIF might serve as NO scavenger and was related to the release of zinc, our study was focused on the interaction of GIF and NO. By studying the reactions of human GIF and human MT1g with SNOC–a type of NO donor, it was found that GIF was more reactive than MT‐1g toward SNOC. In order to further figure out if the high reactivity of GIF in this reaction resulted from the acid‐base catalysis, several mutants were constructed: E23K, E41G/E43A, E23K/E41G/E43A. By studying their basic properties and the reactions toward SNOC, it was found that the S‐nitrosylation of GIF was not only related to the acid‐base catalysis, but also to the accessibility of metal‐thiolate clusters.
Deaggregation Behavior of the Phenol Derivatives
Authors: Xiao Qin , Chen Jian , Yang Hui , Shen Zheng‐Wu , Zhou Xiu‐Jia , Yang Fan , Ji Guo‐Zhen
Published: November 2005

Aggregation and deaggregation behaviors of the phenol derivatives with a branched hydrocarbon chain have been studied in the CH3OH and buffer solution. Combination with the aggregation number measurement and the cell adhesion experiment, the structure effect on the deaggregating abilities of the target molecules are discussed. The results indicate that 2‐phytyl‐4‐methoxylphenol (11) is the most effective deaggregator in the system studied.
Conversion of N‐Acyl‐4‐phenyl/benzyl‐oxazolidine‐2‐thiones into Thiol Esters in the Presence of EtSH‐K2CO3
Authors: Hu Qi , Sun Ya‐Ping , Wu Yi‐Kang
Published: November 2005

N‐Acyl‐β‐hydroxy‐4‐phenyl‐oxazolidinethiones could be rapidly converted into their ethyl thiol esters in high yields by treatment with EtSH at 0 °C in CH3CN or 9:1 (V:V) THF‐H2O in the presence of a catalytic amount of K2CO3.
Stereoselective Synthesis of Novel C‐Disaccharides via Suzuki Cross‐Coupling Reaction
Authors: Li Xiao‐Liu , Xu Xiao‐Ming , Tian Jun , Li Ying‐Xia
Published: November 2005

Novel β‐C‐disaccharides containing a three carbon linkage using exo‐glycal as the precursor were prepared stereoselectively. The synthesis was achieved by the tandem reactions of the stereoselective hydroboration of exo‐glycal and Suzuki cross‐coupling reaction with an iodovinyl sugar, and followed by hydrogenated deprotection under the catalysis of Pd(OH)2/C.
Microencapsulation of Fish Oil by Simple Coacervation of Hydroxypropyl Methylcellulose
Authors: Wu Ke‐Gang , Xiao Qin
Published: November 2005

To improve the oxidative stability and application of fish oil, it was microencapsulated by simple coacervation followed by spray drying. Simple coacervation took place by adding malt dextrin into the emulsion of fish oil and hydroxypropyl methylcellulose (HPMC) solution. Influences of several process parameters on the microencapsulation were evaluated and the oxidative stability and microstructure of microcapsules were analyzed. Results showed that the coacervation could be observed only when dextrose equivalent value (DE value) of malt dextrin, concentration of HPMC solution and fish oil percentage in microcapsules were no more than 20, 5% and 40%, respectively. Moreover, microencapsulation efficiency was higher at HPMC solution concentration of 4% and fish oil percentage of less than 30%. The oxidative stability of fish oil was improved by the microencapsulation and done best in the case of replacing malt dextrin by 40% with acacia. Scanning electronic microscopic photographs showed that the microcapsule obtained was a round, smooth and hollow microcapsule with its wall made up of innumerable small and solid submicrocapsules with the core of fish oil.
Current Developments in HIV Chemotherapy
Authors: Meadows D. Christopher , Gervay‐Hague Jacquelyn
Published: November 2005

HIV infection is the leading cause of death worldwide and despite major advances in treatment, more new cases were diagnosed in 2004 than any previous year. Current treatment regimens are based on the use of two or more drugs from two or more classes of inhibitors termed highly active antiretroviral therapy (HAART). Although HAART is capable of suppressing viral loads to undetectable levels, problems of toxicity, patient adherence, and particularly the emergence of drug‐resistant viruses continues to spur the development of new chemotherapeutics to combat HIV. Clinical candidates from the four existing classes of inhibitors are presented in this review along with lead compounds against new viral targets, with special emphasis on HIV integrase.
Relations between social status and the gonadotrophin‐releasing hormone system in females of two cooperatively breeding species of African mole‐rats, Cryptomys hottentotus hottentotus and Cryptomys hottentotus pretoriae: Neuroanatomical and neuroendocrinological studies
Authors: Du Toit Lydia , Bennett Nigel C. , Katz Arieh A. , Kalló Imre , Coen Clive W.
Published: November 2005

In common (Cryptomys hottentotus hottentotus) and highveld (Cryptomys hottentotus pretoriae) mole‐rats, reproduction is subject to two forms of regulation in addition to incest avoidance. These are the only social bathyergids known to restrict breeding to a particular season; furthermore, subordinate members of their colonies show suppressed reproduction throughout the year. Females from both species were assessed and compared for social and seasonal effects on the gonadotrophin‐releasing hormone (GnRH) system. GnRH‐immunoreactive (ir) structures were visualized immunohistochemically; GnRH content was determined by radioimmunoassay. In both species, GnRH‐ir cell bodies and processes are loosely distributed along the septopreopticoinfundibular continuum, with dense fiber aggregations in the region of the organum vasculosum of the lamina terminalis and median eminence. The two species differ in the rostrocaudal distribution of their GnRH‐ir cell bodies. In highveld mole‐rats, most of these cells are in the septal/preoptic area; in common mole‐rats, more than half of them are in the mediobasal hypothalamus. Compared with common mole‐rats, highveld mole‐rats have a greater total number of GnRH‐ir cell bodies, higher GnRH content, and more intense GnRH immunoreactivity in the median eminence. Within highveld colonies, the nonreproductive females have larger GnRH‐ir cell bodies, more intense GnRH immunoreactivity in the median eminence, and higher GnRH content than the reproductive females; these findings suggest inhibited release of GnRH in the nonreproductive, subordinate females. In contrast, in common mole‐rat females, neither status nor season appears to affect the investigated parameters of the GnRH system; this suggests a predominantly behavioral basis to their suppressed reproduction. J. Comp. Neurol. 494:303–313, 2006. © 2005 Wiley‐Liss, Inc.
Synaptic connectivity in the midget‐parvocellular pathway of primate central retina
Authors: Jusuf Patricia R. , Martin Paul R. , Grünert Ulrike
Published: November 2005

The synaptic connectivity of OFF midget bipolar cells was investigated in the central retina of two primate species, the New World common marmoset monkey, Callithrix jacchus, and the Old World macaque monkey, Macaca fascicularis. In marmosets, dichromatic and trichromatic animals were compared. Bipolar output synapses were identified with antibodies against ribbon proteins (kinesin, C‐terminal binding protein 2) or with an antiserum that recognizes postsynaptic glutamate receptor clusters (GluR4). The midget bipolar cells were identified immunocytochemically with antibodies to CD15 (marmoset) or an antiserum to recoverin (macaque). In marmosets, midget ganglion cells were retrogradely labeled from the parvocellular layers of the dorsal lateral geniculate nucleus. Consistent with previous studies of Old World primates, in marmoset, midget bipolar cells contacted midget ganglion cells at a ratio of 1:1. The number of output synapses made by OFF midget bipolar cells was quantified for 104 cells in two dichromatic marmosets, 108 cells in one trichromatic marmoset, and 118 cells in one macaque. The number of output synapses was comparable for all animals, ranging from 10–71 in the dichromatic marmoset (average 29.7 ± 12.4 SD), 12–86 in the trichromatic marmoset (average 28.6 ± 11.7 SD) and 9–48 in the macaque (average 26.5 ± 9.3 SD) per axon terminal. In all animals the number of output synapses per axon terminal showed a unimodal distribution. Our results suggest that the midget circuitry is comparable in dichromatic and trichromatic animals. J. Comp. Neurol. 494:260–274, 2006. © 2005 Wiley‐Liss, Inc.
Mapping of serotonin, dopamine, and histamine in relation to different clock neurons in the brain of Drosophila
Authors: Hamasaka Yasutaka , Nässel Dick R.
Published: November 2005

Several sets of clock neurons cooperate to generate circadian activity rhythms in Drosophila melanogaster. To extend the knowledge on neurotransmitters in the clock circuitry, we analyzed the distribution of some biogenic amines in relation to identified clock neurons. This was accomplished by employing clock neuron‐specific GAL4 lines driving green fluorescent protein (GFP) expression, combined with immunocytochemistry with antisera against serotonin, histamine, and tyrosine hydroxylase (for dopamine). In the larval and adult brain, serotonin‐immunoreactive (‐IR) neuron processes are in close proximity of both the dendrites and the dorsal terminals of the major clock neurons, the s‐LNvs. Additionally, the terminals of the l‐LNv clock neurons and serotonergic processes converge in the distal medulla. No histamine (HA)‐IR processes contact the s‐LNvs in the larval brain, but possibly impinge on the dorsal clock neurons, DN2. In the adult brain, HA‐IR axons of the extraocular eyelet photoreceptors terminate on the dendritic branches of the LNvs. A few tyrosine hydroxylase (TH)‐IR processes were seen close to the dorsal terminals of the s‐LNvs, but not their dendrites, in the larval and adult brain. TH‐IR processes also converge with the distal medulla branches of the l‐LNvs in adults. None of the monoamines was detectable in the different clock neurons. By using an imaging system to monitor intracellular Ca2+ levels in dissociated GFP‐labeled larval s‐LNvs, loaded with Fura‐2, we demonstrated that application of serotonin induced dose‐dependent decreases in Ca2+. Thus, serotonergic neurons form functional inputs on the s‐LNvs in the larval brain and possibly also in adults. J. Comp. Neurol. 494:314–330, 2006. © 2005 Wiley‐Liss, Inc.
Characterization of central axon terminals of putative stretch receptors in leeches
Authors: Fan Ruey‐Jane , Friesen W. Otto
Published: November 2005

Sensory feedback from stretch receptors, neurons that detect position or tension, is crucial for generating normal, robust locomotion. Among the eight pairs of putative stretch receptors associated with longitudinal muscles in midbody segments of medicinal leeches, only the ventral stretch receptor has been characterized in detail. To achieve the identification of all such receptors, we penetrated large axons in the nerve roots of nerve cords from adult leeches with dye‐filled (Alexa Fluor hydrazide) electrodes. We identified the terminal arborizations of two additional putative stretch receptors with axons in anterior nerve roots and four more such receptors with axons in posterior roots of midbody ganglia. The axons are nonspiking and are individually identifiable by their entry point into the CNS; their projections within the neuropile; the pattern, extent, and orientation of their terminal branches; and the characteristics of small “spike‐like” events. At least two of these axons undergo membrane potential oscillations that are phase locked to the swimming rhythm expressed in nerve cord‐body wall preparations and, at a different phase angle, also in isolated nerve cords. Thus the membrane potentials of at least two axons are phasically modulated by the periphery and hence could provide cycle‐by‐cycle sensory input to coordinate swimming activity. One of these neurons has a soma associated with the dorsal body wall and hence is a putative stretch receptor in dorsal longitudinal muscle. Thus the traveling body wave expressed by swimming leeches may be regulated by sensory feedback from both ventral and dorsal longitudinal muscles. J. Comp. Neurol. 494:290–302, 2006. © 2005 Wiley‐Liss, Inc.
An Efficient Route to Pentasubstituted Phenols
Authors: Khan Faiz Ahmed , Choudhury Sumit
Published: November 2005

A simple and convenient three‐step protocol for the synthesis of pentasubstituted tribromophenols based on the acid‐catalyzed Grob‐type fragmentation of the bicyclic ketone precursors 8a–e in high overall yield is described. The bicyclic ketones 8a–e were obtained in two steps starting from the Diels–Alder cycloadducts 5a–e of β‐substituted vinyl acetates and tetrabromo‐5,5‐dimethoxycyclopentadiene. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Quantum Mechanical Calculation of Coupling Constants in the Configurational Analysis of Flexible Systems: Determination of the Configuration of Callipeltin A
Authors: Bassarello Carla , Zampella Angela , Monti Maria Chiara , Gomez‐Paloma Luigi , D’Auria Maria Valeria , Riccio Raffaele , Bifulco Giuseppe
Published: November 2005

An integrated NMR‐quantum mechanical (QM) approach, relying on the comparison between calculated and experimental J‐values, was applied to the analysis of the relative configuration of four amino acid units (known as AGDHE, D‐aThr1, D‐aThr2 and β‐OMeTyr) contained in callipeltin A, a cyclopeptide endowed with a powerful inhibitory activity on the cardiac sodium/calcium exchanger and also showing interesting antiviral and antifungal properties. In this paper we report the first example of the application of this method to a real case, which allowed the assignment of the relative configuration of the β‐OMeTyr residue and the revision of the configuration of the Thr2 unit in callipeltin A. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Multiple forms of genetic instability within a 2‐Mb chromosomal segment of 3q26.3–q27 are associated with development of esophageal adenocarcinoma
Authors: Lin Lin , Wang Zhuwen , Prescott Michael S. , van Dekken Herman , Thomas Dafydd G. , Giordano Thomas J. , Chang Andrew C. , Orringer Mark B. , Gruber Stephen B. , Moran John V. , Glover Thomas W. , Beer David G.
Published: November 2005

Gene amplification is one of the mechanisms to activate oncogenes in many cancers, including esophageal adenocarcinoma (EA). In the present study, we used two‐dimensional restriction landmark genome scanning to clone a NotI/DpnII fragment that showed increased genomic dosage in 1 of 44 EAs analyzed. This fragment maps to 3q26.3–q27, and subsequent experiments identified two intrachromosomal amplicons within a 10‐Mb DNA segment in 7 of 75 (9%) EAs. The distal amplified‐core region maps centromeric to the PIK3CA locus, and a microsatellite (D3S1754) within this region exhibited significant instability (MSI), in stark contrast to the genomewide microsatellite stability found in EA. D3S1754‐MSI arises in premalignant Barrett's dysplastic cells and preceded amplification of the nascent MSI allele in the corresponding EA. Seven ESTs within the amplified‐core were overexpressed in amplicon‐containing EAs. One of these, EST AW513672, represents a chimeric transcript that initiated from an antisense promoter sequence in the 5′UTR of a full‐length LINE‐1 element (L1‐5′ASP). Similar chimeric transcripts encoding portions of the MET oncogene and the BCAS3 gene also were overexpressed in EAs, suggesting that L1‐5′ASP activation may occur at a broad level in primary EAs. Thus, the fine dissection of a 2‐Mb amplified DNA segment in 3q26.3–q27 in EA revealed multiple genetic alterations that had occurred sequentially and/or concurrently during EA development. This article has supplementary material, available at http://www.interscience.wiley.com/jpages/1045‐2257/suppmat. © 2005 Wiley‐Liss, Inc.
Direct evidence that acutely enhancing serotonin with the selective serotonin reuptake inhibitor citalopram modulates the loudness dependence of the auditory evoked potential (LDAEP) marker of central serotonin function
Authors: Nathan Pradeep J. , Segrave Rebecca , Phan K. Luan , O'Neill Barry , Croft Rodney J.
Published: November 2005

The loudness dependence of the auditory evoked potential (LDAEP) has been suggested as a reliable measure of central serotonin function in humans. The most convincing evidence for a direct relationship between serotonergic function and LDAEP to date has come from animal studies, while evidence in humans has been circumstantial and inconsistent. In the current study, we examine the direct effect of serotonergic modulation with the selective serotonin reuptake inhibitor (SSRI) citalopram on the LDAEP. The study was a double‐blind placebo controlled design in which healthy participants were tested under two acute treatment conditions: placebo and citalopram (20 mg). Enhancement of serotonin function with citalopram in comparison to placebo decreased the slope of the LDAEP (i.e. weaker LDAEP). The findings provide direct evidence in humans, of a relationship between central serotonin function and the LDAEP, supporting findings previously observed in animals and clinical populations. Together the results provide further support for the validity of the LDAEP as a non‐invasive in vivo measure of central serotonin function in humans. Copyright © 2005 John Wiley & Sons, Ltd.
Analysis of 10B antitumoral compounds by means of flow‐injection into ESI‐MS/MS
Authors: Basilico F. , Sauerwein W. , Pozzi F. , Wittig A. , Moss R. , Mauri P. L.
Published: November 2005

Boron neutron capture therapy (BNCT) is a promising binary treatment for cancer. BNCT is based on the ability of the nonradioactive isotope 10B to capture, with a very high probability, thermal neutrons. This nuclear reaction results in two particles (an alpha and a lithium nucleus). The particles have a high biological effectiveness, which is limited in tissue to approximately the diameter of one cell. If the reaction can be limited to a tumor cell, the physical characteristic opens up the possibility to selectively destroy cancer cells, while sparing the surrounding healthy tissue. Quality control of 10B‐containing compounds and their distribution at present are very important, and different analytical methods have been developed, such as time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS), electron energy loss spectrometry (EELS), prompt gamma analysis and inductively coupled plasma‐optical emission spectrometry (ICP‐OES). These methods allow the analyses of 10B, but it is not possible to characterize the specific molecular compounds containing 10B. For this reason, we propose a fast and quantitative method that permits the determination of closo‐undecahydro‐1‐mercaptododecaborate (BSH) and 10boron‐phenylalanine (BPA) and their eventual metabolites. In particular, 10B‐containing compounds are detected by means of flow‐injection electrospray tandem mass spectrometry (FI/ESI‐MS/MS). This approach allows the identification of Boron compounds, BSH and BPA, using tandem mass spectrometry, and quantitative analysis is also possible (c.v. ±4.7%; n = 5; linear range 10–10 000 ng/ml). Furthermore, 10B‐containing compounds were detected in actual biological sample (urine and plasma, diluted 10 000‐ and 1000‐fold, respectively) injecting a small volume (1 µl) of diluted samples. Copyright © 2005 John Wiley & Sons, Ltd.
The role of different phenomena in surface‐activated chemical ionization (SACI) performance
Authors: Cristoni Simone , Rossi Bernardi Luigi , Guidugli Federico , Tubaro Michela , Traldi Pietro
Published: November 2005

In previous studies, the production of ions in an APCI source without any corona discharge was observed, and the intensity of the ion signals showed significant increases on placing a metallic surface at 45° inside an orthogonal ion source. This method was named surface‐activated chemical ionization (SACI). The present study was performed to investigate the mechanisms of ion production with or without the presence of the metallic surface, by varying instrumental parameters and the geometrical configuration. Approximate calculations show that, in the absence of corona discharge and of any additional surfaces, ions cannot be produced by collisional phenomena, because of their low kinetic energy, in the 10−2 to 10−3 eV range. Two alternative possibilities have been considered: the first takes into account that ions may originate by collision of neutral clusters of polar solvent molecules with the APCI source surfaces through clusterelectric effect. The second takes into account that the water dissociation constant kw is temperature dependent, passing from 10−14.1669 at 20 °C to 10−12.4318 at 90 °C. It means that the [H+] varies from 8.3 × 10−8 to 6.1 × 10−7 M going from 20 to 90 °C. Hence, at the high temperatures experimented in the APCI vaporizer, H+ becomes available in solution in molar quantities analogous to those of analyte, and the protonation of the analyte itself can consequently occur. The activation of further ionization processes in the presence of the metallic surface can be reasonably attributed to interactions between gas‐phase analyte molecules and solvent molecules adsorbed on the surface. Experiments performed with a thin layer of deuterated glycerol on the surface led to unequivocal results, i.e. the production of [M + D]+ ions of the analyte. Copyright © 2005 John Wiley & Sons, Ltd.
Positive ion chemistry of esters of carboxylic acids in air plasma at atmospheric pressure
Authors: Marotta Ester , Paradisi Cristina
Published: November 2005

Ionization of esters of carboxylic acids RCOOR′ (R = H, alkyl; R′ = alkyl) within the air plasma of the Atmospheric Pressure Chemical Ionization (APCI) source occurs largely via H+‐transfer and, to a minor extent, via NO+ association. The protonated ester MH+ is normally observed as M2H+ and as higher aggregates (M3H+, M3H+(H2O)) also at high source temperature. The behavior of M2H+ upon collisional activation is consistent with the reported dissociation of proton‐bound dimers to MH+ species that, in turn, fragment according to the known paths of lowest energy. In addition, other important product ions form within the plasma, some in very high relative abundance, which are attributed to ion‐molecule condensation reactions between neutral M and either MH+ or M2H+ resulting in the elimination of CO, R′OH, alkene from the alkoxy moiety of the ester and HCOOH. A general scheme is proposed to account for the experimental observations, which suggest that the encounter complex formed between MH+ and M or between M2H+ and M may either collisionally relax to the protonated dimer or trimer, respectively, or react via covalent bond forming and cleaving steps to eliminate stable neutral molecules. The proposed scheme is supported by both the observed concentration dependence and the temperature dependence of the products relative abundances within the plasma. Such reactions can be the dominant process, as in the case of formate esters. A second significant ionization route involves addition of NO+ to form MnNO+ (n = 1, 2, 3). An additional product corresponding to [M2NO+ − CO2] is also observed with iso‐ and n‐butyl formate esters. Copyright © 2005 John Wiley & Sons, Ltd.
Identification and composition of cuticular hydrocarbons of the major Afrotropical malaria vector Anopheles gambiae s.s. (Diptera: Culicidae): analysis of sexual dimorphism and age‐related changes
Authors: Caputo Beniamino , Dani Francesca R. , Horne Gill L. , Petrarca Vincenzo , Turillazzi Stefano , Coluzzi Mario , Priestman Angela A. , della Torre Alessandra
Published: November 2005

Forty‐eight cuticular hydrocarbons (CHCs) were characterized by gas chromatography‐mass spectrometry from the epicuticular surface of the major Afrotropical malaria vector Anopheles gambiae. The hydrocarbons identified were 14 n‐alkanes, 16 monomethyl alkanes, 13 dimethyl alkanes, 5 alkenes, with main‐chain lengths ranging from C17 to C47, and the results are consistent with those from other Culicidae species. Qualitative differences were not observed between laboratory pools of three females and males, between different age‐groups (0–16 days) and between single field specimens, whereas quantitative differences in CHC profiles were observed. Differences between sexes were more marked in individuals aged 0–2 days than in older ones. Both sexes undergo strong CHC profile changes with age, and individuals aged 0–2 days differ remarkably from the older ones. The possibility of exploiting these changes for estimating the age of mosquito was explored through multivariate analyses of the relative abundance of the compounds, using either the whole CHC profile or a subset of CHCs. Such a method allows us to assign more than 85% of females and 75% of males to the correct age‐group. Although preliminary, these results show that the method is promising, as it has already been shown in Aedes aegypti and An. stephensi. The correct determination of the vector age (particularly in the case of the An. gambiae complex of sibling species) provides valuable information in malaria epidemiology and in evaluation of the effectiveness of vector control strategies. Further efforts will be made to validate this method on single specimens reared in seminatural conditions before being proposed to medical entomologists working in the Afrotropical region. Copyright © 2005 John Wiley & Sons, Ltd.
Marine macroalgae analyzed by mass spectrometry are rich sources of polyunsaturated fatty acids
Authors: De Angelis L. , Risé P. , Giavarini F. , Galli C. , Bolis C. L. , Colombo M. L.
Published: November 2005

Algae from cold water (Canada) and warm water (China) were analyzed for their total lipid content, and for their fatty acid (FA) composition and content. The major findings are that FA from Canadian algae are generally richer in polyunsaturated FA (PUFA), with a higher n‐3/n‐6 FA ratio, and a higher degree of total unsaturation. The 18 C, 4 double bonds FA (18 : 4 stearidonic acid, morotic acid as synonym) was detected in greater amounts in cold water samples. The high levels of total PUFA, and especially of n‐3 FA in Canadian algae, suggests their possible utilizations for nutritional purposes. Copyright © 2005 John Wiley & Sons, Ltd.
Surfactant self‐assembling in gas phase: electrospray ionization‐ and matrix‐assisted laser desorption/ionization‐mass spectrometry of singly charged AOT clusters
Authors: Bongiorno D. , Ceraulo L. , Ruggirello A. , Turco Liveri V. , Basso E. , Seraglia R. , Traldi P.
Published: November 2005

The self‐assembling of sodium bis (2‐ethylhexyl) sulfosuccinate (AOT) in gas phase has been investigated by electrospray ionization‐ and matrix‐assisted laser desorption/ionization mass spectrometry. Large surfactant clusters with an aggregation number close to that found in apolar media have been observed either as positive or negative ions. Moreover, the marked predominance of singly charged species as well as preliminary theoretical calculations strongly suggest an aggregate structure characterized by an internal hydrophilic core hosting the extra charge surrounded by an apolar shell constituted by the surfactant alkyl chains. This structure is similar to that of the more familiar reversed micelles formed when an appropriate surfactant is solubilized in apolar solvents. Finally, similar trends are observed independently either on the ionization technique or the polarity of the solvent used. This, together with the large dependence of the aggregation number on the flow rates, strongly indicates that self‐assembling of the surfactant molecules occurs during the evaporation step. Copyright © 2005 John Wiley & Sons, Ltd.
Generation of high O2 (a1Δg) concentrations in O2/H2 mixtures
Authors: Du Kangyan , Krogh Ole , Setser D. W.
Published: November 2005

The effect of hydrogen on the concentration of singlet oxygen in the a1Δg and b1Σ states, generated from a microwave discharge in O2 and in an O2/Ar mixture, was studied in flow reactors. The addition of hydrogen, in a range of 0.01–1 of concentration of the O2, increased the yields of singlet oxygen by factor of 5–20. In addition to the higher O2 (a and b) concentrations, the addition of hydrogen removed the usual NO2 fluorescence, making observation of the O2(b → X) transition at 762 nm much easier in the flow reactor. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: 12–17, 2006
Delayed autocatalytic behavior of Mn(II) ions at a critical ratio: The effect of structural isomerism on permanganic oxidation of L‐norleucine
Authors: Bahrami Homayoon , Zahedi Mansour
Published: November 2005

The kinetics of the permanganic oxidation process of L‐norleucine, L‐leucine, L‐iso‐leucine, and L‐tert‐leucine in strong acid medium has been investigated using a spectrophotometric technique. Conclusive evidences have proven autocatalytic activity of Mn(II) for these reactions in strong acid medium analogous to weak acid medium, but in the former, ratio of Mn(II) to amino acid concentration must reach a certain amount for autocatalytic phenomenon to emerge, which we call “critical ratio.” This critical ratio depends on the nature of the amino acid employed. Thus considering “delayed autocatalytic behavior” of Mn(II) ions, rate equations satisfying observations for both catalytic and noncatalytic routes have been presented. Kinetic data in a noncatalytic pathway have been fitted to a biparametric equation including inductive, steric, and hyperconjugation correction effects, and it is determined that by shifting the side branch on a carbon chain toward an α‐carbon atom (adjacent to amino acid's functional group) and also adding branches to the α‐carbon atom, the reaction rate in the noncatalytic pathway decreases. Inductive and steric hindrance factors in amino acid's carbon chain are effective on processes' rate both in catalytic and noncatalytic pathways. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: 1–11, 2006
Classic and multivariate modeling treatment of the kinetics and mechanism of isomerization of 5‐cholesten‐3‐one catalyzed by sodium ethoxide
Authors: González‐Hernández J. L. , Canedo M. M. , Grande C.
Published: November 2005

A classic kinetic methodology including the treatment of the steady‐state method and a multivariate modeling kinetic treatment were applied to the kinetics and mechanism of the isomerization reaction of 5‐cholesten‐3‐one to 4‐cholesten‐3‐one catalyzed by EtO− in ethanol absolute. The rate constants, thermodynamic parameters of activation, equilibrium constant, and the isomerization enthalpy were determined. The multivariate modeling kinetic treatment allows us to calculate the concentrations of the species, in which the 3,5‐dienolate is included as a highly reactive intermediate species and was able to discriminate among several applicable mechanisms validating the one comprising two reversible steps. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: 38–47, 2006
Chloraminometric and bromaminometric oxidation of sulfanilic acid in alkaline medium: A comparative kinetic and mechanistic study
Authors: Puttaswamy  , Jagadeesh R. V.
Published: November 2005

The kinetics of oxidation of sulfanilic acid (SAA) by chloramine‐B (CAB) and bromamine‐B (BAB) has been investigated in alkaline medium at 35 ± 0.1°C. The oxidation reaction follows identical kinetics in the case of both the oxidants with first‐order dependence on each [oxidant]o and [SAA]o and an inverse first‐order dependence on [OH−]. The variation of ionic strength, dielectric constant of the medium, addition of the reaction product (benzenesulfonamide), and halide ions showed no significant influence on the reaction rate. Proton inventory studies made in H2O–D2O mixtures for CAB and BAB have been utilized to calculate the isotopic fractionation factor. The reaction has been studied at different temperatures, and activation parameters for the composite reaction have been computed from the Arrhenius plots. N‐Hydroxylaminobenzene‐4‐sulfonic acid was identified as the oxidation product of SAA from IR and GC‐MS analysis. A mechanism consistent with the kinetic results is proposed in which PhSO2NHX (X = Cl or Br) interact with the substrate in the rate‐limiting step. A suitable rate law is derived. The rate of oxidation of sulfanilic acid is about fourfold faster in BAB compared to CAB. The oxidation of SAA brought about by CAT and BAT was also investigated under identical experimental conditions, and the overall rate of oxidation of SAA increases in the order: BAB > BAT > CAB > CAT. This may be attributed to the difference in electrophilicities of Cl+ and Br+ ions and also the van der Waal's radii of chlorine and bromine. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: 48–56, 2006
Detect the sub-wavelength data by applying a
very-small-aperture laser
Authors: Gan Q , Song G , Yang G , Li Y , Chen L
Published: November 2005

We present a theoretical and experimental research
about applying a very-small-aperture laser (VSAL) to detect
sub-wavelength data. Near-field distribution of a VSAL, which is
essential for the application of such near-field devices, will be
affected by the sample or fiber posited in the near-field region
of the aperture. When the device is applied to detect the
sub-wavelength data, the real resolution depends on the near-field
spot size, the divergent angle of the beam and the distance from
the aperture to the sample. Experimental results, including the
near-field detection of the spot and detection of the
sub-wavelength data by using the VSAL, are presented in this
paper. We realize the two dimensional scanning about the
sub-wavelength data (with the width 600 nm) by employing a VSAL
with a 300 nm×300 nm aperture.
Use of the pig caecum model to mimic the human intestinal metabolism of hispidulin and related compounds
Authors: Labib Samira , Hummel Sylvia , Richling Elke , Humpf Hans‐Ulrich , Schreier Peter
Published: November 2005

Up to now, the metabolism of hispidulin (5,7,4′‐trihydroxy‐6‐methoxyflavone), a potent ligand of the central human benzodiazepine receptor, has not been investigated. To elucidate the metabolism of hispidulin in the large intestine, its biotransformation by the pig caecal microflora was studied. In addition, the efficiency of the pig caecal microflora to degrade galangin (3,5,7‐trihydroxyflavone), kaempferol (3,5,7,4′‐tetrahydroxyflavone), apigenin (5,7,4′‐trihydroxyflavone), and luteolin (5,7,3′,4′‐tetrahydroxyflavone) was investigated. Identification of the formed metabolites was performed by high‐performance liquid chromatography (HPLC)‐diode array detection, HPLC‐electrospray ionization‐tandem mass spectrometry, and high‐resolution gas chromatography‐mass spectrometry. The caecal microflora transformed hispidulin to scutellarein (5,6,7,4′‐tetrahydroxyflavone), an effective α‐glucosidase inhibitor, and 3‐(4‐hydroxyphenyl)‐propionic acid; galangin to phenylacetic acid and phloroglucinol; kaempferol to 4‐hydroxyphenylacetic acid, phloroglucinol, and 4‐methylphenol; apigenin to 3‐(4‐hydroxyphenyl)‐propionic acid and 3‐phenylpropionic acid, and luteolin to 3‐(3‐hydroxyphenyl)‐propionic acid, respectively. To elucidate to what extent different hydroxylation patterns on the B‐ring influence the degradation degree of flavonoids, the conversions of galangin and kaempferol as well as that of apigenin and luteolin were compared with those of quercetin (3,5,7,3′,4′‐pentahydroxyflavone) and chrysin (5,7‐dihydroxyflavone), respectively. Regardless of the flavonoid subclass, the presence of a hydroxy group at the 4′‐position seems to be a prerequisite for fast breakdown. An additional hydroxy group at the B‐ring did not affect the degradation degree.
Pyrolytic acrylamide formation from purified wheat gluten and gluten‐supplemented wheat bread rolls
Authors: Claus Achim , Weisz Georg M. , Schieber Andreas , Carle Reinhold
Published: November 2005

Recent studies have revealed different acrylamide formation mechanisms, e. g. from carnosine (N‐β‐alanyl‐L‐histidine) and aminopropionamide as additional precursors. The occurrence of acrylamide in food matrices devoid of common precursors such as meat supports an additional formation pathway. Gluten was recovered from wheat flour by water extraction. Starch, reducing sugars and amino acids were removed using α‐amylase and NaCl solution and were completely absent in the purified gluten fraction. The gluten was dry heated at temperatures ranging from 160 to 240°C for 8 to 12 min and analyzed for acrylamide and cinnamic amide using liquid chromatography‐tandem mass spectrometry. Acrylamide could be detected up to 3997 μg/kg gluten dry weight. Cinnamic amide was detected and unambiguously identified in the gluten samples, thus confirming the proposed formation of acrylamide from proteins. After gluten addition to bread roll dough, protein pyrolysis to form acrylamide in the complex food matrix was assessed. Contents of asparagine and reducing sugars were diminished due to the addition of the gluten. In contrast to the expectation with respect to the well‐established common formation mechanism of acrylamide, it increased from 53.4 to 63.9 μg/kg (+20%), which was in good correlation with the higher proportion of gluten. As demonstrated by the t‐test, the increase in acrylamide was significant when comparing 0 and 15% gluten addition. Additionally, cinnamic amide could be found in crusts of bread rolls. Thus, evidence for pyrolytic formation of acrylamide from wheat gluten was provided.
Natural flavonoids are potent inhibitors of glycogen phosphorylase
Authors: Jakobs Sandra , Fridrich Diana , Hofem Sabine , Pahlke Gudrun , Eisenbrand Gerhard
Published: November 2005

There is little known about effects to be expected from high intake of flavonoids with respect to regulation of glucose/glycogen homeostasis. Glucose/glycogen homeostasis is mainly regulated by glycogen synthase (GS) and glycogen phosphorylase (GP). We investigated effects of naturally occurring flavonoids with varying substitution pattern on the activity of isolated muscle GP. Almost all flavonoids tested inhibited phosphorylated, active GPa, as well as unphosphorylated, adenosine monophosphate‐activated GPb. However, inhibition of GPa was two‐to‐fourfold stronger than that of GPb. The flavonol quercetin and the anthocyanidins cyanidin and delphinidin turned out to be the most potent inhibitors of GPa, with concentration values where enzymatic activity is 50% of the respective control in the low micromolar range (< 5 μM). Furthermore, by comparing GPa inhibitory activity of typical representatives from all known flavonoid classes, structural elements of flavonoids required for effective GP inhibition could be identified.
Photodegradation mechanism and stabilization of polyphenylene oxide and rigid‐rod polymers
Authors: So Ying‐Hung
Published: November 2005

Poly(2,4‐dimethyl‐1,4‐phenylene oxide) (PPO), poly(benzo[1,2‐d:5,4‐d′]bisoxazole‐2,6‐diyl‐1,4‐phenylene) (PBO) and poly(benzo[1,2‐d:4,5‐d′]bisthiazole‐2,6‐diyl‐1,4‐phenylene) (PBZT), which are polymers with extended conjugated structures, undergo a self‐sensitized photo‐induced electron‐transfer reaction. A second component is not required. This article presents many similar observations on these polymers when they are exposed to light and evidence to support the proposed photo‐induced electron‐transfer mechanism. Methods to stabilize these polymers against photo‐oxidation are also described. Workers investigating other conjugated polymeric systems may find the experimental methods, observations and polymer stabilization approaches discussed in this review useful. Copyright © 2005 Society of Chemical Industry
Proteome analysis of combined effects of androgen and estrogen on the mouse mammary gland
Authors: Zhang Lijun , Liu Xin , Zhang Jian , Cao Rui , Lin Ying , Xie Jinyun , Chen Ping , Sun Yi , Li Daiqiang , Liang Songping
Published: November 2005

We and other investigators have previously shown that estrogen and androgen have synergistic effects on the growth of mammary epithelial ducts and alveoli in the Noble mouse. However, the molecular mechanisms behind the synergy are unknown. In the present study, we treated female FVB mice with 17‐estrodial (E2) and 5‐dihydrotestosterone‐bezonate (DHT‐B) using slow‐releasing hormone pellets for 7 months. Dissection showed that hormone treatment caused atypical hyperplasia of mammary ducts and alveoli. A functional proteomic approach was used to study the holistic protein changes in mammary glands. 2‐DE was used to separate proteins. Twenty‐five protein spots that were differentially expressed in hormone‐treated tissues compared to the control were identified by MALDI‐TOF‐MS, and ESI‐quadrupole‐TOF‐MS, which include some proteins that are correlative with response to estrogen and androgen stimulation, cells differentiation and growth, signal transduction, metabolism, etc. Real‐time RT‐PCR was carried out to verify the different expression. These results offered some clues to understand the function of E2 and DHT‐B.
Ligand‐independent orphan receptor TR2 activation by phosphorylation at the DNA‐binding domain
Authors: Khan Shaukat Ali , Park Sung Wook , Huq M. D. Mostaqul , Wei Li‐Na
Published: November 2005

In a previous report we demonstrated protein kinase C (PKC)‐mediated phosphorylation of the ligand‐binding domain (LBD) of orphan nuclear receptor TR2. In this report, we provide the evidence of PKC‐mediated phosphorylation of the DNA‐binding domain (DBD) of TR2. Two PKC target sites were predicted within the DBD, at Ser‐170 and Ser‐185, but only Ser‐185 was confirmed by MS. Phosphorylation of DBD facilitated DNA binding of the TR2 receptor and its recruiting of coactivator p300/CBP‐associated factor (P/CAF). Ser‐185 was required for DNA binding, whereas both Ser‐170 and Ser‐185 were necessary for receptor interaction with P/CAF. The P/CAF‐interacting domain of TR2 was located in its DBD. A double mutant (Ser‐170 and Ser‐185) of TR2 significantly lowered the activation of its target gene RARβ2. This study provides the first evidence for ligand‐independent activation of TR2 orphan receptor through PTM at the DBD, which enhanced its DNA‐binding ability and interaction with coactivator P/CAF.