bluuebunny/crossref_metadata_2025_split huggingface dataset:
Temperature dependence of thermally‐carbonized porous silicon humidity sensor
Authors: Björkqvist M. , Paski J. , Salonen J. , Lehto V.‐P. 
Published: May 2005

AbstractThermal carbonization of porous silicon (PS) at 820 °C under acetylene atmosphere is an appropriate method for humidity sensing purposes. It produces stable and hydrophilic surface still maintaining originally large specific surface area of PS. We report the temperature dependence of various electrical param‐ eters measured for the thermally‐carbonized PS humidity sensor. Capacitance of the sensor in dry air (6 RH%) is almost constant at various temperatures, whereas in higher relative humidity values, the temperature dependence becomes evident. The resistance variation of the sensor is less dependent on RH as the temperature increases. While the capacitance showed linear behavior as a function of temperature, the resistance had a clear non‐linear temperature dependence. In order to get information about the effects of frequency on capacitance values, we measured a phase angle and admittance of the sensor as a function of frequency at three different temperatures in low and high humidity. According to these results, it is preferable to operate this sensor construction using low frequency (<1 kHz). (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Properties of cubic GaN films obtained by nitridation of porous GaAs(001)
Authors: Kidalov V. V. , Sukach G. A. , Revenko A. S. , Bayda A. D. 
Published: May 2005

AbstractWith the help of nitridation of porous GaAs(001) in nitrogen plasma thin films of cubic‐GaN were obtained. The conclusion was made that the quality of the GaN films is dependent on the degree of porosity of the GaAs substrate. XPS spectra were used to investigate the chemical composition of porous GaAs substrates, obtained by electrochemical etching. Porous GaAs substrate at first was annealed in a H2 flow at a temperature of 550 °C (with the aim of removing oxygen from the surface of the porous GaAs). Then, the porous GaAs substrate was annealed in atomic nitrogen at a temperature of 400 °C, and then annealed in vacuum at 600 °C. From XPS measurement we determined that the annealing in atomic nitrogen leads to the formation of GaN films. X‐ray diffraction measurements show that cubic GaN on porous GaAs substrate has no tensile strain. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pictorial markings and labels for safe transport and handling of packaged goods
Authors: Singh S. Paul , Singh Jagjit 
Published: May 2005

AbstractThis paper presents the various sources of pictorial markings and warning labels that can be used on packaged goods. Lack of appropriate warnings or markings can result in severe hazards that can affect the safety of individuals and the work environment. The paper shows examples of good and poor applications of warnings and also discusses the various standards that assist in developing appropriate package markings for your goods. New markings recently being developed will also be discussed. Copyright © 2005 John Wiley & Sons, Ltd.
Discrimination of diastereoisomers by electron ionization mass spectrometry in the 1,3‐dioxane series
Authors: Loutelier‐Bourhis C. , Balog M. , Grosu I. , Ramondenc Y. , Plé G. , Lange C. M. 
Published: May 2005

AbstractImportant differences in the electron ionization (EI) mass spectra of cis,cis and trans,trans isomers of some 2(r)‐R‐2,4(R),6(S)‐trimethyl‐1,3‐dioxanes are recorded and the significant preference for the fragmentation with the cleavage of the axial substituents at C(2) position is revealed. The fragmentation pattern is elucidated by high‐resolution mass measurements, metastable ion spectra and linked‐scan mass spectrometry. Copyright © 2005 John Wiley & Sons, Ltd.
Serum protein profiling by miniaturized solid‐phase extraction and matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Callesen Anne K. , Mohammed Shabaz , Bunkenborg Jakob , Kruse Torben A. , Cold Søren , Mogensen Ole , Christensen Rene dePont , Vach Werner , Jørgensen Per E. , Jensen Ole N. 
Published: May 2005

AbstractSerum profiling by matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) holds promise as a clinical tool for early diagnosis of cancer and other human diseases. Sample preparation is key to achieving reproducible and well‐resolved signals in MALDI‐MS; a prerequisite for translation of MALDI‐MS based diagnostic methods to clinical applications. We have investigated a number of MALDI matrices and several miniaturized solid‐phase extraction (SPE) methods for serum protein concentration and desalting with the aim of generating reproducible, high‐quality protein profiles by MALDI‐MS. We developed a simple protocol for serum profiling that combines a matrix mixture of 2,5‐dihydroxybenzoic acid and α‐cyano‐4‐hydroxycinnamic acid with miniaturized SPE and MALDI‐MS. Functionalized membrane discs with hydrophobic, ion‐exchange or chelating properties allowed reproducible MALDI mass spectra (m/z 1000–12 000) to be obtained from serum. In a proof‐of‐principle application, SPE with chelating material and MALDI‐MS identified protein peaks in serum that had been previously reported for distinguishing a person diagnosed with breast cancer from a control. These preliminary results indicate that this simple SPE/MALDI‐MS method for serum profiling provides a versatile and scalable platform for clinical proteomics. Copyright © 2005 John Wiley & Sons, Ltd.
Diagnostic protein discovery using liquid chromatography/mass spectrometry for proteolytic peptide targeting
Authors: Koomen John M. , Zhao Haitao , Li Donghui , Nasser Waleed , Hawke David H. , Abbruzzese James L. , Baggerly Keith A. , Kobayashi Ryuji 
Published: May 2005

AbstractA peptide targeting method has been developed for diagnostic protein discovery, which combines proteolytic digestion of fractionated plasma proteins and liquid chromatography coupled to electrospray time‐of‐flight mass spectrometry (LC/ESI‐TOFMS) profiling. Proteolysis prior to profiling overcomes molecular weight limitations and compensates for the poor sensitivity of matrix‐assisted laser desorption/ionization (MALDI) protein profiling. LC/MS increases the peak capacity compared to crude fractionation techniques or single sample MALDI analysis. Differentially expressed peptides are targeted in the mass chromatograms using bioinformatic techniques and subsequently sequenced with MALDI tandem MS. In a model study comparing pancreatic cancer patients to controls, 74% of the peptide targets were successfully sequenced. This profiling method was superior to previous experiments using single sample MALDI analysis for protein profiling or proteolytic peptide profiling, because more potential protein markers were identified. Copyright © 2005 John Wiley & Sons, Ltd.
Use of a five‐channel multiplexed electrospray quadrupole time‐of‐flight hybrid mass spectrometer for metabolite identification
Authors: Leclercq Laurent , Delatour Claude , Hoes Ilse , Brunelle Françoise , Labrique Xavier , Castro‐Perez José 
Published: May 2005

AbstractMetabolism data provided with reduced cycle time has become of increasing importance for the early evaluation of DMPK properties of drugs in discovery. In this regard, quadrupole time‐of‐flight hybrid mass spectrometers (Q‐TOF) can provide very reliable metabolite identification via accurate mass measurement of ions and the consequent access to the elemental composition of the metabolite. However, due to their cost, they are often used for drug metabolism studies on later stage drug candidates or to address challenging metabolism questions. A new prototype, consisting of a five‐channel multiplexed electrospray ionization (ESI) source on a Q‐TOF with one channel used for lock‐mass compound infusion, was evaluated for metabolite identification. The goal was to increase the sample throughput of a single ESI‐MS system by a factor of 4, while maintaining efficient metabolite separation in high‐performance liquid chromatography (HPLC) as well as adequate sensitivity and mass accuracy, and ultimately improve the speed and quality of metabolism studies supporting drug discovery. The analytical performance of the system was assessed by evaluating the sensitivity and mass accuracy (using real in vitro and in vivo samples), inter‐channel differences in retention times, MS/UV response, and cross‐talk among channels. The sensitivity using the multiplexed ESI source was on average 2‐fold lower than with single ESI, correlating well with previous literature data. The mass accuracy was comparable to that obtained using single ESI in both MS and MS/MS modes, making the metabolite identification process using the multiplexed ESI source as reliable as with single ESI. Compound‐dependent differences in ionization efficiencies were observed among channels, and were minimized by analyzing related samples on the same channel. Finally, the level of cross‐talk among channels was acceptable (around 0.3%) and comparable to levels previously published for quantitative applications using multiplexed ESI. The paper also focuses on the advantages and disadvantages of this new approach compared to other approaches in the literature in the field of metabolite identification. Copyright © 2005 John Wiley & Sons, Ltd.
Electrospray ionization mass spectrometry as a tool for determination of drug binding sites to human serum albumin by noncovalent interaction
Authors: Benkestock Kurt , Edlund Per‐Olof , Roeraade Johan 
Published: May 2005

AbstractMost proteins in blood plasma bind ligands. Human serum albumin (HSA) is the main transport protein with a very high capacity for binding of endogenous and exogenous compounds in plasma. Many pharmacokinetic properties of a drug depend on the level of binding to plasma proteins. This work reports studies of noncovalent interactions by means of nanoelectrospray ionization mass spectrometry (nanoESI‐MS) for determination of the specific binding of selected drug candidates to HSA. Warfarin, iopanoic acid and digitoxin were chosen as site‐specific probes that bind to the main sites of HSA. Two drug candidates and two known binders to HSA were analyzed using a competitive approach. The drugs were incubated with the target protein followed by addition of site‐specific probes, one at a time. The drug candidates showed predominant affinity to site I (warfarin site). Naproxen and glyburide showed affinity to both sites I and II. The advantages of nanoESI‐MS for these studies are the sensitivity, the absence of labeled molecules and the short method development time. Copyright © 2005 John Wiley & Sons, Ltd.
Quantification of the plant‐derived hallucinogen Salvinorin A in conventional and non‐conventional biological fluids by gas chromatography/mass spectrometry after Salvia divinorum smoking
Authors: Pichini Simona , Abanades Sergio , Farré Magí , Pellegrini Manuela , Marchei Emilia , Pacifici Roberta , Torre Rafael de la , Zuccaro Piergiorgio 
Published: May 2005

AbstractA gas chromatography method with mass spectrometric detection is described for the determination of Salvinorin A, the main active ingredient of the hallucinogenic mint Salvia divinorum. The method was validated in plasma, urine, saliva and sweat using 17‐α‐methyltestosterone as internal standard. The analytes were extracted from biological matrices with chloroform/isopropanol (9:1, v/v). Chromatography was performed on a 5% phenyl methyl silicone capillary column and analytes were determined in the selected ion monitoring mode. The method was validated over the concentration range 0.015–5 μg/mL plasma, urine and saliva and 0.01–5 μg/patch in the case of sweat. Mean recoveries ranged between 77.1 and 92.7% for Salvinorin A in different biological matrices, with precision and accuracy always better than 15%. The method was applied to the analysis of urine, saliva and sweat from two consumers after smoking 75 mg plant leaves to verify the presence of the active ingredient of S. divinorum in human biological fluids as a biomarker of plant consumption. Salvinorin A was detected in urine (2.4 and 10.9 ng/mL) and saliva (11.1 and 25.0 ng/mL), but not in sweat patches from consumers. Copyright © 2005 John Wiley & Sons, Ltd.
Elucidation of the molecular structure of lipid A isolated from both a rough mutant and a wild strain of Aeromonas salmonicida lipopolysaccharides using electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry
Authors: El‐Aneed Anas , Banoub Joseph 
Published: May 2005

AbstractThe chemical structure of lipid A, isolated by mild acid hydrolysis from a rough mutant and a wild strain of Aeromonas salmonicida lipopolysaccharide, was investigated using electrospray ionization quadrupole time‐of‐flight (QqToF) hybrid tandem mass spectrometry and showed a great degree of microheterogeneity. The chemical structure of the main constituent of this heterogeneous mixture was identified as a β‐D‐(1 → 6) linked D‐glucosamine disaccharide substituted by two phosphate groups, one being bound to the non‐reducing end at position O‐4′ and the other to the position O‐1 of the reducing end of the D‐glucosamine disaccharide. The location of the fatty acids linked to the disaccharide backbone was established by identifying diagnostic ions in the conventional QqToF‐MS scan. Low‐energy collision tandem mass spectrometry analysis of the selected precursor diagnostic ions confirmed, unambiguously, their proposed molecular structures. We have established that myristyloxylauric (C14:0(3‐O(12:0))) acid residues were both N‐2′ and O‐3′ linked to the non‐reducing end of the D‐GlcN residue, and that two 3‐hydroxymyristic (C14:0(3‐OH)) acid chains acylated the remaining positions of the reducing end. The MS and MS/MS data obtained allowed us to determine the complex molecular structure of lipid A. The QqToF‐MS/MS instrument has shown excellent superiority over a conventional quadrupole‐hexapole‐quadrupole tandem instrument which failed to fragment the selected precursor ion. Copyright © 2005 John Wiley & Sons, Ltd.
Liquid chromatography/electrospray mass spectrometric analysis of metabolites from an inhibitory RNA duplex
Authors: Beverly Michael , Hartsough Kim , Machemer Lynn 
Published: May 2005

AbstractLiquid chromatography/mass spectrometry (LC/MS) was used as a method for analyzing the metabolites of a model short interfering RNA (siRNA) duplex. The model siRNA duplex incorporated oligonucleotide stabilizing and protecting chemistries as these have been shown to increase the half‐life of oligonucleotides. Two complementary 23 nucleotide single strands were joined to form the duplex. The intact duplex was analyzed using ion‐pair reversed‐phase chromatography coupled to electrospray ionization mass spectrometry (ESI‐MS). The method used a hexafluoroisopropanol/triethylamine ion‐pairing buffer with a methanol gradient to separate single‐stranded oligonucleotide components from the duplex. This buffer system with ESI also preserved the duplex in the gas phase for analysis by a triple quadrupole mass spectrometer. Using this methodology, in vitro and in vivo metabolites from urine and rabbit ocular vitreous humor were determined and a pattern of duplex siRNA degradation was established. The masses of the metabolites were determined by ESI‐MS and used with the known sequence of the siRNA duplex to identify the metabolites. Over the time course of the metabolism experiments it was shown that the breakdown products of the siRNA are consistent with the nuclease protection given by chemical modifications and that the duplex structure adds additional stability compared to the single strands alone. This study demonstrates that the ability of LC/MS to analyze duplex oligonucleotides has unique benefits for the study of siRNA metabolism. Copyright © 2005 John Wiley & Sons, Ltd.
Fast analysis of low molecular mass compounds present in snake venom: identification of ten new pyroglutamate‐containing peptides
Authors: Wermelinger Luciana Serrão , Dutra Denis L. S. , Oliveira‐Carvalho Ana L. , Soares Márcia Regina , Bloch Carlos , Zingali Russolina B. 
Published: May 2005

AbstractCharacterization of the peptide content in snake venoms can be an important tool for the investigation of new pharmacological lead compounds. For this purpose, single‐step analysis of crude venoms has recently been demonstrated using mass spectrometry (MS) techniques. Reproducible profiles of ions in MS and MS/MS spectra may also be used to compare venoms from different species. In this work matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) was used to obtain mass patterns of the major peptides (<8 kDa) found in pooled venoms from the genera Bothrops and Crotalus. Venoms from five different Bothrops species (B. jararaca, B. insularis, B. alternatus, B. jararacussu, and B. neuwiedi) and three Crotalus species (C. viridis, C. adamanteus and C. durissus terrificus) were analyzed. In agreement with other reports, venoms from Bothrops species contained a variety of peptides in the range m/z 1000–1500, and in some samples larger components (m/z 7000–8000) were detected. In the Crotalus species venoms were rich in peptides ranging from m/z 1000–1500 and 4000–5500. MS/MS experiments on the low molecular mass peptides (m/z 1000–1500) confirmed the presence of ten new bradykinin‐potentiating peptides among venoms from genera Bothrops and Crotalus. In order to determine whether additional peptides could be identified after partial purification, B. jararaca venom was subjected to size‐exclusion chromatography on Sephacryl S‐200, and two distinct low molecular mass pools were analyzed further by MALDI‐TOFMS. No additional peptides were detected from the pool with masses below 2000 Da but a substantial improvement with better resolution was observed for the pool with masses above 7000 Da, indicating that complex samples such as crude snake venoms can be analyzed for low molecular mass peptides using a single‐step procedure. Copyright © 2005 John Wiley & Sons, Ltd.
The synthesis of internal standards for the quantitative determination of sphingolipids by tandem mass spectrometry
Authors: Mills Kevin , Eaton Simon , Ledger Victoria , Young Elisabeth , Winchester Bryan 
Published: May 2005

AbstractNovel internal standards have been synthesised for the quantitative determination by tandem mass spectrometry (MS/MS) of the sphingolipids that accumulate in lysosomal storage diseases. The [d4]C16‐ and [d47]C24‐isoforms of galactosylceramide (CMH), lactosylceramide (CDH), globotriaosylceramide (CTH), cerebroside sulphate, sphingomyelin and GM1‐, GM2‐ and GM3‐gangliosides were synthesised by the reaction of their lyso‐forms with the acid chlorides of hexadecanoic 5,5,6,6‐d4 acid ([d4]‐palmitic acid) and tetracosanoic‐d47 acid ([d47]‐lignoceric acid), respectively. The acid chlorides were formed using oxalyl chloride. The structures of the internal standards were confirmed by MS/MS. The fragmentation pattern of each novel compound was similar to that of the corresponding natural form of the sphingolipid, making it a good internal standard for the quantitative determination of the natural sphingolipid by ESI‐MS/MS. Characteristic product ions were identified for each compound. Copyright © 2005 John Wiley & Sons, Ltd.
Sulfonamide bond cleavage in benzenesulfonamides and rearrangement of the resulting p‐aminophenylsulfonyl cations: application to a 2‐pyrimidinyloxybenzylaminobenzenesulfonamide herbicide
Authors: Wang Hao‐Yang , Zhang Xiang , Guo Yin‐Long , Dong Xi‐Cheng , Tang Qing‐Hong , Lu Long 
Published: May 2005

AbstractThe gas‐phase fragmentation/rearrangement reactions of compound 1, [2‐(4,6‐dimethoxypyrimidin‐2‐yloxy)‐benzyl]‐[4‐(piperidine‐1‐sulfonyl)phenyl]amine, have been examined by Fourier transform ion cyclotron resonance mass spectrometry (FTICR‐MS). The analyses reveal that under sustained off‐resonance irradiation collision‐induced dissociation (SORI‐CID) conditions in the FTICR cell, protonated 1 undergoes two competitive pathways initiated by different protonation positions. The first pathway is initiated by protonation on the amino group and yields only one fragment ion due to loss of the entire benzenesulfonamide moiety. In the second pathway, protonation of the sulfonamide group leads to cleavage of a sulfonamide bond with loss of the neutral piperidine, followed by loss of SO via a sulfonyl cation rearrangement. An intramolecular SNAr mechanism is proposed to rationalize the rearrangement of the p‐aminophenylsulfonyl cation and the resulting SO loss. To test the generality of this process, SORI‐CID spectra of protonated sulfamethoxazole and of the p‐aminophenylsulfonyl cation (SBN) were obtained. For the SBN ion, SORI‐CID experiments as well as density functional theory (B3LYP) calculations show that rearrangement, assigned as a SNAr reaction of the sulfonyl cation group, can account for the observed SO loss process. Candidate transition state structures were optimized at the B3LYP/6‐31+G (d, p) level of theory using the Gaussian98 molecular modeling package. The computational results show that the barrier for SO loss from SBN is much lower than that for SO2 loss, which satisfactorily rationalizes the SORI‐CID experimental results for SBN. Moreover, it is proposed that a fragment ion at m/z 196 in the MS/MS spectrum of protonated 1 is formed via the ion resulting from SO loss via a second intramolecular SNAr mechanism. Copyright © 2005 John Wiley & Sons, Ltd.
A monolithic PNGase F enzyme microreactor enabling glycan mass mapping of glycoproteins by mass spectrometry
Authors: Palm Anders K. , Novotny Milos V. 
Published: May 2005

AbstractWe demonstrate a simple and rapid single‐step method to fabricate an enzyme microreactor incorporating the N‐glycosidase PNGase F (peptide‐N‐glycosidase F) into a porous polymer‐based monolith. The monolith is contained in a capillary format, while the enzyme reactor is ready to use within 1 h of preparation. The monomers making up the monolith, including N‐acryloxysuccinimide for covalent immobilization of the enzyme, are mixed with PNGase F and introduced into the column by capillary force for polymerization/immobilization. Glycoproteins (ribonuclease B, asialofetuin, α1‐acid glycoprotein, and ovalbumin) perfused through the PNGase F reactor were shown to be effectively deglycosylated on a time‐scale of seconds/low minutes using low nanogram to microgram per microliter concentration (corresponding to a total sample consumption of 0.1–20 μg of a glycoprotein). The reactor enzyme activity was shown to be reproducible for at least 8 weeks when used and stored at room temperature. Evaluation was performed by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. Copyright © 2005 John Wiley & Sons, Ltd.