bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vibrational spectroscopy and DFT calculations of di‐amino acid cyclic peptides. Part I: cyclo(Gly‐Gly), cyclo(L‐Ala‐L‐Ala) and cyclo(L‐Ala‐Gly) in the solid state and in aqueous solution
Authors: Mendham Andrew P. , Dines Trevor J. , Snowden Martin J. , Chowdhry Babur Z. , Withnall Robert 
Published: May 2009

AbstractInvestigations of the vibrational spectra of cyclo(Gly‐Gly), cyclo(L‐Ala‐L‐Ala) and cyclo(L‐Ala‐Gly) are reported. Raman scattering and Fourier transform infrared (FTIR) spectra of solid‐state and aqueous protonated samples, as well as their corresponding N‐deuterated isotopomers, have been examined. In addition, density functional theory (DFT) (B3‐LYP/cc‐pVDZ) calculations of molecular structures and their associated vibrational modes were carried out. In each case, the calculated structures of lowest energy for the isolated gas‐phase molecules have boat conformations. Assignments have been made for the observed Raman and FTIR vibrational bands of the cyclic di‐amino acid peptides (CDAPs) examined. Raman polarization studies of aqueous phase samples are consistent with C2 and C1 symmetries for the six‐membered rings of cyclo(L‐Ala‐L‐Ala) and cyclo(L‐Ala‐Gly), respectively. There is a good correlation between experimental and calculated vibrational bands for the three CDAPs. These data are in keeping with boat conformations for cyclo(L‐Ala‐L‐Ala) and cyclo(L‐Ala‐Gly) molecules, predicted by the ab initio calculations, in both the solid and aqueous solution states. However, Raman spectroscopic results might infer that cyclo(L‐Ala‐Gly) deviates only slightly from planarity in the solid state. The potential energy distributions of the amide I and II modes of a cis‐peptide linkage are shown to be significantly different from those of the trans‐peptides. For example, deuterium shifts have shown that the cis‐amide I vibrations found in cyclo(Gly‐Gly), cyclo(L‐Ala‐L‐Ala), and cyclo(L‐Ala‐Gly) have larger N‐H contributions compared to their trans‐amide counterparts. Compared to trans‐amide II vibrations, cis‐amide II vibrations show a considerable decrease in NH character. Copyright © 2009 John Wiley & Sons, Ltd.
Quantitative Raman spectroscopy: speciation of cesium silicate glasses
Authors: Malfait Wim J. 
Published: May 2009

AbstractThe silicate speciation forms an important aspect of the structure of silicate melts, a subject of interest to both the earth‐ and materials science communities. In this study, the Qn speciation of binary cesium silicate glasses was studied by Raman spectroscopy. A method to extract the equilibrium constant from a set of Raman spectra is presented, and the least‐squares optimization algorithm is given (in Supporting Information). Log(K), the equilibrium constant of the speciation reaction, 2Q3 = Q4 + Q2, equals −2.72 ± 0.11 at the glass transition. This extends the previously established correlation between log(K) and the inverse of the ionic radius of the network modifier to cesium. Copyright © 2009 John Wiley & Sons, Ltd.
The content and distribution of condensed tannins in different species of the genus sorghum (Sorghum Moench) and their effect on seed protein electrophoresis
Authors: Liu Min‐Xuan , Wang Yun‐Wen , Han Jian‐Guo , Mao Pei‐Sheng 
Published: May 2009

AbstractBACKGROUND: The interaction between condensed tannins (CTs) and seed protein in varieties of sorghum interferes with protein extraction and the separation by electrophoresis, so electrophoresis can not be used widely for determining seed purity and identifying a variety. The objective of this research was to classify the effect of CTs on the extraction of seed storage proteins and on their analysis by SDS–PAGE, and to search for a promising solution to reduce the negative effect of CTs in sorghum.RESULTS: The vanillin–HCl test confirmed that CTs were localised mainly in the glumes of grain sorghum, but distributed in every fraction of sudangrass. Samples with high CT content did not produce any bands in the gel after electrophoresis. Removal of the glumes and pericarp/testa prevented the influence of CTs on electrophoresis for grain sorghum but had little effect for sudangrass. Adding tannin/catechin to the protein extraction of sorghum kernel decreased the number of bands in the gel. Adding polyvinylpyrrolidine to the protein extraction of sudangrass increased the bands.CONCLUSION: Tannin–protein interactions are responsible for the absence of bands in varieties with high CT content. For grain sorghum, decortication can prevent the influence. Adding polyvinylpyrrolidine during the extraction of seed protein could solve the problem of tannin–protein interactions for varieties of sudangrass. Copyright © 2009 Society of Chemical Industry
Development and validation of UPLC for the determination of phenolic compounds and furanic derivatives in Brandy de Jerez
Authors: Schwarz Mónica , Rodríguez M. Carmen , Guillén Dominico A. , Barroso Carmelo G. 
Published: May 2009

AbstractBrandy and other aged distillates are a rich source of polyphenols. For brandies, contact with wood during ageing makes an important contribution to their polyphenols content. This paper describes the use of a previously devised ultra performance LC (UPLC) method to study the polyphenols content of Brandy de Jerez. UPLC is a new technique in LC offering several potential advantages, especially the reduction of time. Analyses of brandy performed by HPLC were repeated by UPLC. A special UPLC analytical column (Acquity UPLC BEH C18 column, 100×2.1 mm), with a particle size of 1.7 μm, forms part of this system. Using the UPLC system enabled the time needed for analysis to be reduced to one tenth of the time needed in the conventional HPLC system. In conclusion, the separation factor results of the UPLC were compared to those obtained using HPLC methods; this demonstrated that simple, high efficiency UPLC gradients are viable and advantageous substitutes for traditional analysis of polyphenols in brandy by HPLC. The method enabled 14 phenolic compounds to be identified and determined in 33 different commercial brandies, and this allowed them to be differentiated in function of quality.
GC‐MS/MS multi‐residue method for the determination of organochlorine pesticides, polychlorinated biphenyls and polybrominated diphenyl ethers in human breast tissues
Authors: Medina Cecilia M. , Pitarch Elena , Portolés Tania , López Franciso J. , Hernández Félix 
Published: May 2009

AbstractIn this work, a multiresidue method for the quantification and confirmation of around 30 organohalogenated compounds in human breast tissue samples has been developed. Analytes tested included organochlorine (OC) (pesticides and polychlorinated biphenyls) and organobromine (OBr) (polybrominated diphenyl ether) compounds. The approach is based on a simple extraction with hexane, followed by a SPE clean‐up using silica cartridges and final measurement by GC coupled to triple quadrupole MS. Analyses were performed in both ionizations, electron impact (EI) (selected reaction monitoring (SRM) mode) and negative chemical ionization (NCI) (selected ion recording (SIR) mode). Three isotopically labeled standards were added before extraction and used as surrogates: HCB‐13C6, lindane‐D6 and p,p′‐DDE‐D8. The method was validated in terms of accuracy, precision, LOQ and LOD and confirmation reliability, using breast tissue spiked at three concentration levels in the range 1–100 ng/g for OC compounds and at two levels 0.1 and 10 ng/g for OBr compounds (0.5 and 50 ng/g for BDE 209). The usefulness of the developed method was tested by the analysis of real human samples, giving as a result the detection of several OC and OBr compounds in different samples analyzed. The acquisition of at least two SRM transitions (in EI) or ions (in NCI) per analyte allowed positive findings to be confirmed by accomplishment of ion ratios between the quantification and the confirmation transitions or ions.
Separation of D‐psicose and D‐fructose using simulated moving bed chromatography
Authors: Van Duc Long Nguyen , Le Thai‐Hoang , Kim Jin‐Il , Lee Ju Weon , Koo Yoon‐Mo 
Published: May 2009

AbstractSimulated moving bed (SMB) processes have been widely used in the sugar industries with ion‐exchange resin as a stationary phase. D‐Psicose, a rare monosaccharide known as a valuable pharmaceutical substrate, was synthesized by the enzymatic conversion from D‐fructose. The SMB process was adopted to separate D‐psicose from D‐fructose. Before the SMB experiment, the reaction mixture including D‐psicose and D‐fructose was treated by a deashing process to remove contaminants, such as buffers, proteins, and other organic materials. Four columns packed with Dowex 50WX4‐Ca2+ (200–400 mesh) ion‐exchange resins were used in the four‐zone SMB. Single‐step frontal analysis was performed to estimate the isotherm parameters of each monosaccharide. The operating conditions of the SMB process were determined based on the Equilibrium Theory. According to the simulation of the SMB process, the purity and yield of extract product (D‐psicose) achieved were 99.04 and 97.46%, respectively and those of raffinate product (D‐fructose) were 99.06 and 99.53%, respectively. Under the optimized operating condition, complete separation (extract purity = 99.36%, raffinate purity = 99.67%) was achieved experimentally.
Ion‐exchanger synthesis using reversible addition‐fragmentation chain transfer polymerization
Authors: Unsal Ender , Uguzdogan Erdal , Patir Süleyman , Tuncel Ali 
Published: May 2009

AbstractAn ion‐exchanger with polyanionic molecular brushes was synthesized by a “grafting from” route based on “surface‐controlled reversible addition‐fragmentation chain transfer polymerization” (RAFT). The RAFT agent, PhC(S)SMgBr was covalently attached to monodisperse‐porous poly(dihydroxypropyl methacrylate‐co‐ethylene dimethacrylate), poly(DHPM‐co‐EDM) particles 5.8 μm in size. The monomer, 3‐sulfopropyl methacrylate (SPM), was grafted from the surface of poly(DHPM‐co‐EDM) particles with an immobilized chain transfer agent by the proposed RAFT protocol. The degree of polymerization of SPM (i. e. the molecular length of the polyanionic ligand) on the particles was controlled by varying the molar ratio of monomer/RAFT agent. The particles carrying polyanionic molecular brushes with different lengths were tested as packing material in the separation of proteins by ion exchange chromatography. The columns packed with the particles carrying relatively longer polyanionic ligands exhibited higher separation efficiency in the separation of four proteins. Plate heights between 130–200 μm were obtained. The ion‐exchanger having poly‐(SPM) ligand with lower degree of polymerization provided better peak‐resolutions on applying a salt gradient with higher slope. The molecular length and the ion‐exchanger group content of polyionic ligand were adjusted by controlling the degree of polymerization and the grafting density, respectively. This property allowed control of the separation performance of the ion‐exchanger packing.
Simplifying the setup for vacuum‐outlet GC: Using a restriction inside the injection port
Authors: de Zeeuw Jaap , Reese Shawn , Cochran Jack , Grossman Scott , Kane Tom , English Chris 
Published: May 2009

AbstractThe application of vacuum GC has several advantages over pressurized GC. One of the key characteristics is that the optimal gas velocity is very high. Combined with short capillary columns of wide internal diameter, this results in short analysis times using standard GC‐MS equipment. To make vacuum GC possible using a GC‐MS system, a restriction must be positioned at the injection side of the column. This restriction is usually made of deactivated 0.1 mm i.d. fused‐silica tubing which is coupled to the analytical column. Such restrictions will work, but practical challenges are found in coupling, reducing dead volume and robustness. A new way of making restrictions is by incorporating the restriction into the injection port. Using well‐defined short pieces of fused silica with internal diameter of 0.025 mm, one can make a restriction using a Press‐Tight® type connector, and position this inside the injection port. By doing this, the restriction is very short and at high temperature all the time. Activity plays a minimal role, and also leaks will not be an issue as the coupling is in 100% inert gas. Data obtained using this concept is promising as vacuum GC becomes easier and more robust.
Evaluation of a generalized use of the log Sum(k+1)AA descriptor in a QSRR model to predict peptide retention on RPLC systems
Authors: Bodzioch Karolina , Dejaegher Bieke , Baczek Tomasz , Kaliszan Roman , Vander Heyden Yvan 
Published: May 2009

AbstractAt the current state of knowledge, the rational optimization of the chromatographic separation of peptides, as well as the identification of proteins in proteomics are challenges for analytical chemists. In this paper the generalized applicability of a recently derived descriptor log Sum(k+1)AA in a QSRR equation to model peptide retention in RP‐LC systems was evaluated. For that purpose, two sets of peptides analyzed on dissimilar RP‐LC systems were considered. A first set of 28 peptides was measured on 17 columns/systems, while a second of 70 peptides was eluted on four. The aim of this work was to confirm the usefulness of the partly experimental log Sum(k+1)AA descriptor for the prediction of peptides retention compared to the initially applied, fully experimental log SumAA descriptor. The verification of the predictive abilities of both QSRR models, applying either the initial or the alternative descriptor, was done by using the leave‐one‐out and leave‐three‐out cross‐validation procedures. The results seem to demonstrate that the QSRR model with log Sum(k+1)AA, for which the retention measurement of only seven out of 20 existing amino acids is necessary, possesses similar or in some cases even better predictive abilities than that containing log SumAA.
Determination of basic azaarenes in aviation kerosene by solid‐phase extraction and HPLC‐fluorescence detection
Authors: Rocha da Luz Elaine , Mota Gonsalves Thiago Fernando , Queiroz Aucélio Ricardo 
Published: May 2009

AbstractSPE in combination with HPLC and fluorescence detection has been used for sensitive determination of six basic azaarenes (7,8‐benzoquinoline, 7,9‐dimethylbenz[c]acridine, 9‐amino‐1,2,3,4‐tetrahydroacridine, 9‐methylacridine, acridine, and dibenz[a,j]acridine) in aviation kerosene (jet fuel). SPE was performed in a single step using a strong cation exchange sorbent. The HPLC system consisted of C18 column with a selected detection program of optimal λexc and λem. A gradient elution with ACN and phosphate buffer (pH 6.5) at a flow rate of 1 mL/min allowed efficient and fast separation of azaarenes within 15 min. The LOD and LOQ values (S/N ratio 3:1 and 10:1, respectively) were between 0.0013 and 0.021 and from 0.0044 to 0.072 ng per injection. The calibration curves showed linear behavior from the LOQ to 250 μg/L (r2 >0.99). For the spiked concentration of 6.0 μg/L, recoveries were from 92 to 107% for jet fuel samples, except for 9‐amino‐1,2,3,4‐tetrahydroacridine, which presented 68% recovery. The proposed method was applied to the quantification of those six basic azaarenes in one commercial kerosene and in three aviation kerosene samples. The presence of 7,8‐benzoquinoline (up to 3.2 μg/L) and dibenzo[a,j]acridine (up to 6.3 μg/L) was confirmed in aviation kerosene.
Electrophoretic methods for separation of nanoparticles
Authors: Surugau Noumie , Urban Pawel L. 
Published: May 2009

AbstractThis article reviews progress in the application of electrophoretic techniques for the separation of nanoparticles. Numerous types of nanoparticles have recently been synthesised and integrated into different products and procedures. Consequently, analytical methods for the efficient characterisation of nanoparticles are now required. Several studies have revealed that gel electrophoresis can readily be used for separating nanoparticles according to their size or shape. However, many other studies focused on separation of nanoparticles by CE. In some cases nanoparticles could be separated by CZE, simply using pure buffer as the BGE. In other studies, buffer additives (most often SDS) were used, enabling fast separations of metallic nanoparticles by size. Other CE methods also allowed for separation of nanoparticle conjugates with biomolecules. Dielectrophoresis is yet another electrophoretic technique useful in separation and characterisation of nanoparticles; particularly nanotubes. Detection methods often used after electrophoretic separation include UV/Vis absorption and fluorescence spectroscopy. Examples of recent and relevant older reports are presented here. The authors conclude that electrophoretic methods for nanoanalysis can provide inexpensive and efficient tools for quality assurance and safety control; and as a consequence, they can augment transfer of nanotechnologies from research to industry.
Two‐dimensional coordination polymer matrix for solid‐phase extraction of pesticide residues from plant Cordia salicifolia
Authors: Viana de Carvalho Pedro Henrique , Santos Barreto Alysson , Rodrigues Marcelo O. , de Menezes Prata Vanessa , Barreto Alves Péricles , de Mesquita Maria Eliane , Alves Júnior Severino , Navickiene Sandro 
Published: May 2009

AbstractThe 2D coordination polymer (∞[Gd(DPA)(HDPA)]) was tested for extraction of acephate, chlorpropham, pirimicarb, bifenthrin, tetradifon, and phosalone from the medicinal plant Cordia salicifolia, whose extracts are commercialized in Brazil as diuretic, appetite suppressant, and weight loss products, using GC/MS, SIM. Considering that there are no Brazilian regulations concerning maximum permissible pesticide residue concentrations in medicinal herbs, recovery experiments were carried out (seven replicates), at two arbitrary fortification levels (0.5 and 1.0 mg/kg), resulting in recoveries in range of 20 to 107.7% and SDRSDs were between 5.6 and 29.1% for ∞[Gd(DPA)(HDPA)] sorbent. Detection and quantification limits for herb ranged from 0.10 to 0.15 mg/kg and from 0.15 to 0.25 mg/kg, respectively, for the different pesticides studied. The developed method is linear over the range assayed, 0.5–10.0 μg/mL, with correlation coefficients ranging from 0.9975 to 0.9986 for all pesticides. Comparison between ∞[Gd(DPA)(HDPA)] sorbent and conventional sorbent (neutral alumina) showed similar performance of ∞[Gd(DPA)(HDPA)] polymeric sorbent for three (bifenthrin, tetradifon, and phosalone) out of six pesticides tested.
Screening for generalized anxiety disorder symptoms in the wake of terrorist attacks: A study in primary care
Authors: Ghafoori Bita , Neria Yuval , Gameroff Marc J. , Olfson Mark , Lantigua Rafael , Shea Steven , Weissman Myrna M. 
Published: May 2009

AbstractLittle is known about the mental health impact of terrorism beyond posttraumatic stress disorder (PTSD) and depression. The associations between exposure to the September 11, 2001 (9/11) attacks in New York City and generalized anxiety disorder (GAD) symptoms were examined in a sample of 929 primary care patients. After controlling for PTSD, depression, panic and substance use disorders, and pre‐9/11 trauma, patients who screened positive (vs. negative) for GAD symptoms were roughly twice as likely to report having a loved one at the 9/11 disaster site, twice as likely to know someone who was killed by the attacks, and twice as likely to know someone who was involved with the rescue/recovery efforts after the disaster. Implications for treatment and future research are discussed.
Management of meningoencephalic herniation of the temporal bone: Personal experience and literature review
Authors: Sanna Mario , Paolo Fois , Russo Alessandra , Falcioni Maurizio 
Published: May 2009

AbstractObjectives/Hypothesis:Temporal bone meningoencephalic herniation is a rare condition with potentially dangerous complications. The aim of this study is to analyze the pathogenesis, clinical presentation, surgical treatment, and postoperative outcome of 133 cases of surgically confirmed temporal bone meningoencephalic herniations. A review of the literature is also presented.Study Design:Retrospective case series (quaternary referral otology and skull base center).Methods:This study is based on the analysis of the collected data of 133 cases of temporal bone meningoencephalic herniations surgically treated from 1984 to 2006. The follow‐up ranged from 12 to 204 months with a mean of 38.4 months.Results:Meningoencephalic herniations were divided into four etiologic groups: spontaneous (24.8%), secondary to chronic otitis media (21.8%), iatrogenic (45.9%), and posttraumatic (7.5%). Different surgical techniques were used for treatment: transmastoid approach (27.8%), middle cranial fossa approach (27.8%), combined technique (transmastoid plus minicraniotomy, 3%), and middle ear obliteration with blind sac closure of the external auditory canal (41.4%).Conclusions:Temporal bone meningoencephalic herniations are potentially life threatening, and surgery must take place expeditiously. The choice of the most appropriate surgical approach must be based on the localization and size of the herniated tissue, preoperative auditory function, the presence of active infection, intraoperative cerebrospinal fluid leak, and concomitant pathology. Laryngoscope, 2009
Brain‐derived nerve growth factor in the treatment of sensorineural hearing loss
Authors: Meen Eric , Blakley Brian , Quddusi Taeed 
Published: May 2009

AbstractObjectives/Hypothesis:A possible medical treatment for sensorineural hearing loss using brain‐derived nerve growth factor (BDNF) was explored. The hypothesis is that direct intracochlear application of BDNF will result in improved hearing.Study Design:Animal research study.Methods:Significant hearing loss was created using cisplatin in 11 guinea pigs. One month later, bilateral cochleostomies were performed placing 0.05 μg of BDNF in one cochlea of each animal prior to plugging with connective tissue. The other cochlea served as a control. Auditory brain‐stem response (ABR) testing was then carried out for three months at 6,000, 8,000, 12,000, and 24,000 Hz.Results:ABR thresholds were better in the treated ear for all frequencies. Threshold differences were statistically significantly better two months after treatment (general linear model, repeated measures P = .045).Conclusions:Intracochlear application of BDNF may prevent hearing loss. Laryngoscope, 2009
Advanced UV Lasers Enable Precision Processing
Authors: Rauch Torsten , Delmdahl Ralph 
Published: May 2009

AbstractLasers with ultraviolet (UV) output offer unique benefits for processing a wide range of materials. In particular, the short wavelength, high energy UV photons experience less diffraction than longer visible or infrared wavelengths, which enables materials processing at higher spatial resolution. In addition, UV lasers micromachine primarily by non‐thermal means, thus minimizing the heat affected zone due to processing. As a result, UV lasers are now employed for many demanding, high precision tasks in semiconductor fabrication, display manufacture, medical device production, therapeutic medical procedures and scientific research. This article explores some of these applications as well as recent advances in the laser technology that has been developed to service them.