bluuebunny/crossref_metadata_2025 huggingface dataset:
Remote Sensing and Wetland Ecology: a South African Case Study
Authors: De Roeck Els R. , Verhoest Niko E.C. , Miya Mtemi H. , Lievens Hans , Batelaan Okke , Thomas Abraham , Brendonck Luc
Published: May 2008

Remote sensing offers a cost efficient means for identifying and monitoring wetlands over a large area and at different moments in time. In this study, we aim at providing ecologically relevant information on characteristics of temporary and permanent isolated open water wetlands, obtained by standard techniques and relatively cheap imagery. The number, surface area, nearest distance, and dynamics of isolated temporary and permanent wetlands were determined for the Western Cape, South Africa. Open water bodies (wetlands) were mapped from seven Landsat images (acquired during 1987 – 2002) using supervised maximum likelihood classification. The number of wetlands fluctuated over time. Most wetlands were detected in the winter of 2000 and 2002, probably related to road constructions. Imagery acquired in summer contained fewer wetlands than in winter. Most wetlands identified from Landsat images were smaller than one hectare. The average distance to the nearest wetland was larger in summer. In comparison to temporary wetlands, fewer, but larger permanent wetlands were detected. In addition, classification of non-vegetated wetlands on an Envisat ASAR radar image (acquired in June 2005) was evaluated. The number of detected small wetlands was lower for radar imagery than optical imagery (acquired in June 2002), probably because of deterioration of the spatial information content due the extensive pre-processing requirements of the radar image. Both optical and radar classifications allow to assess wetland characteristics that potentially influence plant and animal metacommunity structure. Envisat imagery, however, was less suitable than Landsat imagery for the extraction of detailed ecological information, as only large wetlands can be detected. This study has indicated that ecologically relevant data can be generated for the larger wetlands through relatively cheap imagery and standard techniques, despite the relatively low resolution of Landsat and Envisat imagery. For the characterisation of very small wetlands, high spatial resolution optical or radar images are needed. This study exemplifies the benefits of integrating remote sensing and ecology and hence stimulates interdisciplinary research of isolated wetlands.
Carta al editor 1
Authors: Astudillo Machuca Adelina
Published: May 2008

Apreciados Editores:

En primer lugar deseo felicitar la iniciativa de editar esta revista, que se constituye en una ventana abierta para la intercomunicación y puesta en común del trabajo científico...
Carta No. 2
Authors: Benavides Olga Lucía
Published: May 2008

Apreciados Editores:

Permítanme felicitarlos por la Revista de Productos Naturales...
COMPOSICIÓN QUÍMICA DEL ACEITE ESENCIAL DE LOS FRUTOS DE Piper hispidum Kunth
Authors: Delgado Avila Wilman A. , Cuca Suárez Luis E.
Published: May 2008

Se analizó el aceite esencial de frutos de P. hispidum Kunth obtenido por el método de hidrodestilación con un rendimiento del 0,8%. Empleando cromatografía de gases espectrometría de masas se identificaron y cuantificaron cerca de 70 compuestos que representan aproximadamente el 99% del aceite obtenido. De acuerdo con la composición relativa, el 49,7% corresponde a monoterpenos, el 37,5% a monoterpenoides, el 3,7% a compuestos aromáticos y un 9,1% a sesquiterpenos. Como compuestos mayoritarios se identificaron limoneno (16,3%), β-pineno (14,5%), α-pineno (13,5%), linalool (9,6%), α-terpineol (8,5%), 1,8-cineol (5,1%), alcanfor (4,4%), camfeno (4,2%), endoborneol (4,0%), trans-pulegol (2,2%), p-cimeno (2,2%), dibencilo (1,2%) y óxido de cariofileno (1,1%). Los demás componentes identificados se encuentran en una concentración relativa menor al 1%.
Performance of Bilingual Speakers on the English and Spanish Versions of the Hearing in Noise Test (HINT)
Authors: Weiss Deborah , Dempsey James J.
Published: May 2008

This study compared the performance of bilingual participants on the English and Spanish versions of the Hearing in Noise Test (HINT). The participants were divided into an early bilingual (EB) group and a late bilingual (LB) group based on age of second-language acquisition. All participants
acquired Spanish as their first language (L1) and English as a second language (L2). Care was taken to ensure that all participants demonstrated at least a "good competence level" for self-rated speaking, understanding, reading, and writing skills in both English and Spanish. Results
revealed superior performance on the Spanish HINT versus the English HINT in both quiet and in noise for both groups of participants. Significant differences in performance were noted for the EB versus the LB participants. A number of possible explanations for superior performance in L1 are
provided, and implications for educating students in their L2 are discussed. Este estudio compara el desempeño de participantes bilingües en las versiones en inglés y en español de la Prueba de Audición en Ruido (HINT). Se dividieron los participantes en un
grupo bilingüe temprano (EB) y un grupo bilingüe tardío, con base en la edad de adquisición de la segunda lengua. Todos los participantes adquirieron el español como su primera lengua (L1) y el inglés como su segunda lengua. Se tuvo cuidado que todos los
participantes demostraran al menos un "buen nivel de aptitud" auto-calificado, en las habilidades para hablar, entender, leer y escribir tanto el inglés como el español. Los resultados revelaron desempeños superiores en el HINT en español versus el HINT
en inglés, tanto en silencio como en ruido, para ambos grupos de participantes. Se observaron diferencias significativas en el desempeño para los participantes del EB versus el LB. Se aporta un número de posibles explicaciones para un desempeño superior en L1, y
se discuten las implicaciones para educar estudiantes en su L2.
Distribution of ThetaY226 in a Clinical Population
Authors: Bishop Richard , Church Gerald T.
Published: May 2008

ThetaY (Y) is the phase angle between the admittance vector and the conductance component in an acoustical system. It is determined by the relative contributions of the system's conductance and susceptance. The magnitude of the admittance vector has received almost
exclusive attention in clinical admittance measurements. The phase angle, providing information on the relative contribution of energy-dissipating and energy-storing components, has been largely overlooked. One hundred and ninety-five clinical records obtained over a five-year period were
used to investigate the distribution of Y and its relationship to other tympanometric variables. The results show that Y has a reasonably symmetrical distribution and is not strongly related to other tympanometric variables. The data suggest that Y
may account for a different subset of the total variance than more commonly measured variables. Y appears to meet the criteria of independence and distribution, justifying further study to evaluate its clinical utility. ThetaY (Y) es el ángulo de
fase entre el vector de admitancia y el componente de conductancia en un sistema acústico. Está determinado por las contribuciones relativas de la conductancia y la susceptancia del sistema. La magnitud del vector de admitancia ha recibido una atención casi exclusiva en
las mediciones clínicas de admitancia. El ángulo de fase, que proporciona información sobre la contribución relativa de los componentes de disipación de energía y de almacenamiento de energía, ha sido despreciado. Se utilizaron ciento noventa
y cinco registros clínicos obtenidos durante un período de cinco años para investigar la distribución del (Y) y su relación con otras variables timpanométricas. Los resultados muestran que el (Y) tiene una distribución
razonablemente simétrica y no está fuertemente relacionada con otras variables timpanométricas. Los datos sugieren que el (Y) puede ser responsable de un subgrupo diferente de la variancia total, más que otras variables más comúnmente
medidas. El (Y) parece llenar los criterios de independencia y distribución, justificando estudios ulteriores para evaluar su utilidad clínica.
Observations on Mastoid versus Ear Canal Recorded Cochlear Microphonic in Newborns and Adults
Authors: Riazi Mariam , Ferraro John A.
Published: May 2008

The cochlear microphonic (CM) may play an important role in the diagnosis of auditory neuropathy (AN) in newborns. However, since the CM tends to mirror the waveform of the acoustic stimulus, conscientious recording methodology must be applied to separate true response from artifact.
The difficulty in achieving this separation has limited the clinical usefulness of the CM. In an effort to call attention to the importance of recording protocol when measuring the CM, the present study was designed to optimize CM recordings in humans by investigating the following parameters:
(1) secondary minus electrode recording site (mastoid versus ear canal [EC]), (2) stimulus parameters, and (3) grounding and shielding conditions. Normative data were collected in full-term newborns (n = 7) and adults (n = 4) with no known risk factors for cochlear or retrocochlear pathology.
Results suggest that the CM is easier to separate from stimulus artifact using an EC electrode and toneburst stimuli. In addition, electromagnetic shielding and grounding of the electrode cables and the acoustic transducer were effective in reducing and/or eliminating stimulus artifact. Results
from this normative study may be helpful in improving the diagnostic utility of the CM in AN and other hearing-related disorders. La microfónica coclear (CM) puede jugar un papel importante en el diagnóstico de la neuropatía auditiva (AN) en recién nacidos. Sin
embargo, dado que la CM tiende a reflejar la forma de onda del estímulo acústico, debe aplicarse una metodología concienzuda de registro de estímulos para separar la verdadera respuesta del artefacto. La dificultad para lograr esta separación ha limitado
la utilidad clínica de la CM. En un esfuerzo por llamar la atención respecto de la importancia del protocolo de registro cuando se mide la CM, el estudio presente fue diseñado para optimizar los registros de la CM en humanos, por medio de la investigación de los
siguientes parámetros: (1) sitio secundario menor del electrodo de registro (mastoides vs. canal auditivo [EC], (2) parámetros del estímulo, y (3) condiciones de aterrizaje y de escudo protector. Se colectaron datos normativos en recién nacidos de término
(n = 7) y adultos (n = 4), sin factores de riesgo para patología coclear o retro-coclear. Los resultados sugieren que la CM es fácil de separar de los artefactos del estímulo utilizando un electrodo EC y un estímulo de tipo burst tonal. Además, el aterrizaje
de los cabes de los electrodos y del transductor acústico, así como un escudo electromagnético fueron efectivos para reducir y/o eliminar los artefactos del estímulo. Los resultados de este estudio normativo pueden ser útiles para mejorar la utilidad diagnóstica
de la CM en la AN y otros trastornos relacionados con la audición.
Development of a Clinical Test of Musical Perception: Appreciation of Music in Cochlear Implantees (AMICI)
Authors: Spitzer Jaclyn B. , Mancuso Dean , Cheng Min-Yu
Published: May 2008

The purpose of this study was to develop a test to assess the ability of persons with cochlear implants (CIs) to interpret musical signals. Up to this time, the main direction in outcomes studies of cochlear implantation has been in relation to speech recognition abilities. With improvement
in CI hardware and processing strategies, there has been a growing interest in musical perception as a dimension that could improve greatly users' quality of life. The Appreciation of Music in Cochlear Implantees (AMICI) test was designed to measure the following abilities: discrimination
of music versus noise; identification of musical instruments (from a closed set); identification of musical styles (from a closed set); and recognition of individual musical pieces (open set). The first phase of the study was test development and recording. The second phase entailed presentation
of a large set of stimuli to normal listeners. Based on phase 2 findings, an item analysis was performed to eliminate stimuli that were confusing or resulted in high error rates in normals. In phase 3, hearing-impaired participants, using cochlear Implants, were assessed using the beta version
of the AMICI test. El propósito de este estudio fue desarrollar una prueba para evaluar la capacidad de las personas con implantes cocleares (CI) para interpretar señales musicales. Hasta ahora, el enfoque principal en estudios de desempeño de implantación coclear
se ha concentrado las habilidades de reconocimiento del lenguaje. Con el mejoramiento del hardware y de las estrategias de procesamiento de los CI, ha existido un interés creciente en la percepción de la música, como una dimensión que podría incrementar importantemente
la calidad de vida de los usuarios. La Prueba de Apreciación Musical en Implantados Cocleares (AMICI) fue diseñado para medir las siguientes aptitudes: discriminación de la música vs. ruido; identificación de instrumentos musicales (de un grupo cerrado);
identificación de estilos musicales (de un grupo cerrado); y reconocimiento de piezas musicales independientes (grupo abierto). La primera fase de la prueba fue evaluar desarrollo y registro. La segunda fase involucró la presentación de un amplio grupo de estímulos
a oyentes normales. Con base en los hallazgos de la fase 2, se realizó un análisis de ítems para eliminar estímulos que eran confusos o producían una alta tasa de errores en los normales. En la fase 3, los participantes hipoacúsicos, usando sus implantes
cocleares, fueron evaluados usando la versión beta de la Prueba AMICI.
Differential correlates of reactive and proactive aggression in Asian adolescents: relations to narcissism, anxiety, schizotypal traits, and peer relations
Authors: Seah Suzanne L. , Ang Rebecca P.
Published: May 2008

This study investigated relationship between reactive and proactive aggression, and narcissism, anxiety, schizotypal traits, and interpersonal relations in a sample of 698 Asian adolescents from Grades 7 to 9. Proactive aggression was found to be significantly associated with narcissism, whereas reactive aggression was significantly associated with anxiety, schizotypal traits, and poor interpersonal relations. Study findings provide support from a cross‐cultural standpoint for differential correlates of reactive and proactive aggression and represent an initial attempt to illustrate the generalizability of existing findings on the distinction between the two subtypes in an Asian context. Implications for theory building of the reactive–proactive aggression typology are discussed. Aggr. Behav. 34:553–562. 2008. © 2008 Wiley‐Liss, Inc.
Solvent‐etching preparation and enhanced emission of acetylferrocene organometallic nanoparticles
Authors: Yuan Pin‐Shi , Wu Qing‐Sheng
Published: May 2008

A new type of acetylferrocene organometallic nanoparticles with the diameter of about 70 nm was prepared by a simple solvent‐etching method and characterized by scanning electron microscope, transmission electron microscope and X‐ray diffractometer. Their optical properties were presently studied by FT‐IR, UV–visible absorption spectra and fluorescence spectra. The fluorescence intensity was increased in the nanoparticles compared with that of bulk materials in solid state. The formation mechanism of the nanoparticles along with their optical properties is discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Copper perchlorate hexahydrate: a highly efficient catalyst for the cyanosilylation of aldehydes
Authors: Majhi Anjoy , Kim Sung Soo , Kim Ho Sub
Published: May 2008

Cu(ClO4)2·6H2O has been found to be an efficient catalyst for cyanosilylation reaction of aldehydes in THF at room temperature with low catalytic loading (1.0 mol%) in short reaction time (mostly within 10 min). Copyright © 2008 John Wiley & Sons, Ltd.
Kinetic study of methacrylate copolymerization systems by thermoanalysis methods
Authors: Habibi Ali , Vasheghani‐Farahani Ebrahim
Published: May 2008

The free‐radical solution copolymerization of isobutyl methacrylate with lauryl methacrylate in the presence of an inhibitor was studied with thermoanalysis methods. A set of inhibited polymerization experiments was designed. Four different levels of initial inhibitor/initiator molar ratios were considered. In situ polymerization experiments were carried out with differential scanning calorimetry. Furthermore, to determine the impact of the polymerization media on the rate of initiation, the kinetics of the initiator decomposition were followed with nonisothermal thermoanalysis methods, and the results were compared with in situ polymerization counterparts. The robust M‐estimation method was used to retrieve the kinetic parameters of the copolymerization system. This estimation method led to a reasonable prediction error for the dataset with strong multicollinearity. The model‐free isoconversional method was employed to find the variation of the Arrhenius activation energy with the conversion. It was found that robust M‐estimation outperformed existing methods of estimation in terms of statistical precision and computational speed, while maintaining good robustness. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008
Photocrosslinked electrospun chitosan‐based biocompatible nanofibers
Authors: Jin Yu , Yang Dongzhi , Zhou Yingshan , Ma Guiping , Nie Jun
Published: May 2008

The electrospun fibers chitosan/polyvinyl alcohol (CS/PVA) were crosslinked by the incorporation of photocrosslinking agent poly(ethyleneglycol)‐600‐dimethacrylate (PEGDMA) and photoinitiator 2‐hydroxy‐1‐[4‐(2‐hydroxyethoxy)phenyl]‐2‐methyl‐1‐propanone (HEPK) into the spinning solutions and a subsequent irradiation by UV light. The photocrosslinking process of CS‐based nanofibers was studied by the Fourier transform infrared spectra, and the water resistance was investigated by scanning electron microscopy (SEM) and water swelling measurement. The results indicated that the water resistance of photocrosslinked CS‐based nanofibers was improved obviously and the swelling ratio decreased with the increasing content of PEGDMA/HEPK. When the concentration of crosslinking agent was 20 wt %, the swelling ratio value decreased to half of that in none crosslinking CS/PVA nanofiber membranes, further increasing the concentration of crosslinking agent to 50 wt %, the swelling ratio value was one eighth of the none crosslinking CS/PVA nanofiber membranes. Cytotoxicity evaluation by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay indicated that the photocrosslinked CS‐based fiber membranes were nontoxic to L929 cells. Results from cell culture SEM imaging showed that cells which exhibited the spindle shape could grow properly on the surface of nanofibrous structure of the CS/PVA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
μ‐Gels as support materials for dinuclear olefin polymerization catalysts
Authors: Schilling Marc , Görl Christian , Alt Helmut G.
Published: May 2008

μ‐Gels which consist of poly(organosilicon) networks can be employed as efficient support materials for ethylene polymerization catalyst precursors. Alkylaluminum cocatalysts can be fixed on the μ‐gel surfaces using the PHT (“partially hydrolyzed trimethylaluminum”) method. The influence of different aluminum/water ratios on the ethylene polymerization properties of these heterogeneous systems is investigated. Dinuclear silicon bridged zirconium complexes are used as catalyst precursors yielding polyethylenes with broad or bimodal molecular weight distributions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Mechanical behavior and microhardness of swollen natural rubber loaded with carbon black
Authors: Abu‐Abdeen M. , Almulhem Abdalaziz A. , Sedky A.
Published: May 2008

The mechanical behavior and microhardness characteristics of a natural rubber vulcanizate loaded with 40 phr high abrasion furnace carbon black swollen in kerosene were studied. The measured parameters (i.e., the Young's modulus, tensile strength, and elongation at break) varied with the swelling time in kerosene. The hardness degree decreased as the swelling time in kerosene increased. Different models were applied to describe this mechanical behavior. The Mooney–Rivilin relation agreed with the experimental data at low extension ratios, whereas the Blatz relation agreed at high extension ratios only. The strain rate sensitivity was taken into account to describe this mechanical behavior. The strain energy density as a function of the swelling time in kerosene was calculated with three different equations. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis and properties of organic/inorganic hybrid nanoparticles prepared using atom transfer radical polymerization
Authors: Wang Tzong‐Liu , Ou Chia‐Chih , Yang Chien‐Hsin
Published: May 2008

The synthesis of organic/inorganic hybrid materials was conducted by atom transfer radical polymerization (ATRP) of styrene and methyl methacrylate (MMA) from the surface of silica colloids. Colloidal initiators were prepared by the functionalization of silica nanoparticles with (3‐(2‐bromoisobutyryl)propyl) dimethylethoxysilane (BIDS). Well‐defined polymer chains were grown from the nanoparticle surfaces to yield individual particles composed of a silica core and a well‐defined outer polystyrene (PS) or poly(methyl methacrylate) (PMMA) layer. Fourier transform infrared (FTIR) and solid state 13C and 29Si‐NMR spectroscopy confirmed the successful modification of nanosilica surfaces. Subsequent grafting of polymers on silica surfaces by ATRP was also performed with success based on FTIR and NMR data. Scanning electron microscopy (SEM) and silicon mapping showed both hybrid materials were homogeneous dispersion systems. Energy dispersive X‐ray spectrometer (EDS) analysis indicated that the BIDS initiator was covalently attached on surfaces of silica nanoparticles and ATRP of styrene and MMA were accomplished. Thermogravimetric analysis (TGA) results displayed higher thermal stabilities for both nanohybrids in comparison with the linear‐type vinyl polymers. Contact angle measurements revealed the nanomaterials character for both silica‐based hybrid materials. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Modification induced by alpha particle irradiationin Makrofol polycarbonate
Authors: Nouh S. A. , Mohamed Amal , El Hussieny H. M. , Hegazy T. M.
Published: May 2008

Makrofol DE 1‐1 CC polycarbonate samples were exposed to alpha particles of initial energies at levels between 5.1 and 34 MeV. The modifications induced in polycarbonate samples due to the alpha particle irradiation have been studied through different characterization techniques such as X‐ray diffraction (XRD), infrared spectroscopy, intrinsic viscosity, and color difference studies. The infrared spectroscopy indicated that the intensities of the characteristic absorption bands decrease with increasing the deposited alpha energy in the range 5.1–8.4 MeV, indicating that the degradation is the dominant mechanism at this range. At the same time, an increase in the OH groups was observed at the same energy range 5.1–8.4 MeV due to the degradation of carbonate group and the H abstraction from the polymer backbone to form hydroxyl groups. The degradation reported by IR spectroscopy enhanced the degree of ordering in the degraded samples as revealed by XRD technique. Additionally, this degradation decreases the intrinsic viscosity from 0.56 to 0.43 at 35°C, indicating a decrease in the average molecular mass. The non irradiated Polycarbonate polymer is nearly colorless. It showed significant darkness sensitivity towards alpha particle irradiation, indicated by an increase in the color intercept L* from 33.6 to 36.7. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Citation counting, citation ranking, and h‐index of human‐computer interaction researchers: A comparison of Scopus and Web of Science
Authors: Meho Lokman I. , Rogers Yvonne
Published: May 2008

This study examines the differences between Scopus and Web of Science in the citation counting, citation ranking, and h‐index of 22 top human‐computer interaction (HCI) researchers from EQUATOR—a large British Interdisciplinary Research Collaboration project. Results indicate that Scopus provides significantly more coverage of HCI literature than Web of Science, primarily due to coverage of relevant ACM and IEEE peer‐reviewed conference proceedings. No significant differences exist between the two databases if citations in journals only are compared. Although broader coverage of the literature does not significantly alter the relative citation ranking of individual researchers, Scopus helps distinguish between the researchers in a more nuanced fashion than Web of Science in both citation counting and h‐index. Scopus also generates significantly different maps of citation networks of individual scholars than those generated by Web of Science. The study also presents a comparison of h‐index scores based on Google Scholar with those based on the union of Scopus and Web of Science. The study concludes that Scopus can be used as a sole data source for citation‐based research and evaluation in HCI, especially when citations in conference proceedings are sought, and that researchers should manually calculate h scores instead of relying on system calculations.
Negative emotion does not enhance recall skills in adults with autistic spectrum disorders
Authors: Deruelle C. , Hubert B. , Santos A. , Wicker B.
Published: May 2008

Recent empirical findings suggest a significant influence of emotion on memory processes. Surprisingly, although emotion‐processing difficulties appear to be a hallmark feature in autism spectrum disorders (ASD), their impact on higher‐level cognitive functions, such as memory, has not been directly studied in this population. The aim of this study was to address this issue by assessing whether the emotional valence of visual scenes affects recall skills in high‐functioning individuals with ASD. To this purpose, their recall performance of neutral and emotional pictures was compared with that of typically developing adults (control group). Results revealed that while typically developing individuals showed enhanced recall skills for negative relative to positive and neutral pictures, individuals with ASD recalled the neutral pictures as well as the emotional ones. Findings of this study thus point to reduced influence of emotion on memory processes in ASD than in typically developing individuals, possibly owing to amygdala dysfunctions.
An investigation of the effects of dog visits on depression, mood, and social interaction in elderly individuals living in a nursing home
Authors: Phelps Kristin A. , Miltenberger Raymond G. , Jens Tess , Wadeson Heather
Published: May 2008

The present study investigated the effects of weekly dog visits on depression scores, mood, and social interaction in elderly individuals living in a nursing home. Five elderly residents participated in baseline assessments for 4–8 weeks and then received weekly dog visits for 6 weeks. Assessments, consisting of weekly observations of social interaction and paper and pencil measures of mood and depression, continued during the dog visits. The effect of dog visits was evaluated in a multiple baseline across participants design. Dog visits did not improve depression scores, mood (with the exception of one resident), or social interaction (with the exception of one resident). Residents did interact with the dog during the visits, however, and reported that they enjoyed the visits. These results show that dog visits do not always have therapeutic effects and suggest the need for further research in the area before the beneficial effects of dog visits can be substantiated. Copyright © 2008 John Wiley & Sons, Ltd.
Enhanced electrochemiluminescence of Ru(bpy)32+ by flavone compounds
Authors: Lin Zhenyu , Chen Jinhua , Chen Guonan
Published: May 2008

Flavones such as morin, rutin, quercitrin, quercetin and wogonin were found to be able to strongly enhance the electrochemiluminescence (ECL) of the Ru(bpy)32+ system. Based on this, a novel ECL method with good stability and reproducibility could be developed for determination of flavones. Under the optimum conditions, the enhanced ECL intensity was linear with the flavones concentration in a wide range. The detection limits (defined as S:N = 3) for morin, rutin, quercitrin, quercetin and wogonin were 3.2 × 10–7 mol/L, 4.3 × 10–7, 1.8 × 10–7, 8.0 × 10–8 and 1.0 × 10–7 mol/L, respectively. In addition, the possible mechanism for the Ru(bpy)32+ ECL system in the presence of flavones is also discussed. Copyright © 2008 John Wiley & Sons, Ltd.
Reduced adhesion formation following laparoscopic versus open colorectal surgery
Authors: Dowson H M , Bong J J , Lovell D P , Worthington T R , Karanjia N D , Rockall T A
Published: May 2008

Background

Adhesion formation is common after abdominal surgery. This study aimed to compare the extent of adhesion formation following laparoscopic and open colorectal surgery.

Methods

An observational study was undertaken to identify adhesions in patients undergoing laparoscopy after previous laparoscopic or open colectomy. Adhesions were scored according to a system validated for interobserver (median κ = 0·80) and intraobserver (κ = 0·82) agreement. The primary endpoint was the overall adhesion score (0–10); a secondary endpoint was the adhesion score at the main incision site (0–6).

Results

Forty-six patients were recruited (13 laparoscopic and 33 open colectomy). In most patients (n = 29), laparoscopy was performed for tumour staging before liver resection. The median (interquartile range) overall adhesion score was 7 (5–8) in the open group and 0 (0–3) in the laparoscopic group (P < 0·001). A similar difference was found for the main incision score: 6 (4–6) versus 0 (0–0) (P < 0·001).

Conclusion

There may be a reduction in adhesion formation following laparoscopic compared with open colectomy, although the small sample size limits this conclusion.
Identification of N,N‐dimethyltryptamine and β‐carbolines in psychotropic ayahuasca beverage
Authors: Gambelunghe Cristiana , Aroni Kyriaki , Rossi Riccardo , Moretti Luca , Bacci Mauro
Published: May 2008

Recently many people have shown great interest in traditional indigenous practices and popular medicine, involving the ingestion of natural psychotropic drugs. We received a request to analyze and determine the nature of a dark green liquid with a dark brown plant sediment, which the police had seized at an airport and inside the home of a person belonging to the ‘Santo Daime’ religious movement. Gas chromatography/mass spectrometry analysis of the extract identified N,N‐dimethyltryptamine, a potent hallucinogen, and the β‐carboline alkaloids harmine and harmaline, revealing monoamine oxidase A‐inhibiting properties. These substances are typical components of Ayahuasca, a South American psychotropic beverage obtained by boiling the bark of the liana Banisteriopsis caapi together with the leaves of various admixture plants, principally Psychotria viridis. Copyright © 2008 John Wiley & Sons, Ltd.
Direct TLC resolution of atenolol and propranolol into their enantiomers using three different chiral selectors as impregnating reagents
Authors: Bhushan Ravi , Tanwar Shivani
Published: May 2008

Direct resolution of racemic atenolol and propranolol into their enantiomers was achieved by normal phase TLC on silica gel plates impregnated with optically pure l‐tartaric acid, (R)‐mandelic acid and (–)‐erythromycin as chiral selectors. Different solvent systems were worked out to resolve the enantiomers. Spots were detected using iodine vapour. The TLC method was validated for linearity, limit of detection and limit of quantification. The influence of pH, temperature and concentration of chiral selector was studied. Copyright © 2008 John Wiley & Sons, Ltd.
Separation assay of histamine and its metabolites in biological specimens
Authors: Toyo'oka Toshimasa
Published: May 2008

This review summarizes the determination methods for histamine and the metabolites in biological specimens by separation techniques, such as gas chromatography, liquid chromatography and capillary electrophoresis. The typical applications using these methods are also described in this review together with the characteristics of the methods. Copyright © 2008 John Wiley & Sons, Ltd.
Rapid and sensitive liquid chromatography tandem mass spectrometry method for the quantification of ambroxol in human plasma
Authors: Hu Wanqun , Xu Yu , Liu Fei , Liu Aixiang , Guo Qingxiang
Published: May 2008

A sensitive, specific and rapid high‐performance liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method was described and validated for the quantification of ambroxol in human plasma using enalaprilat as the internal standard (IS). Chromatographic separation was performed on a Lichrospher CN column with a mobile phase of methanol and water (containing 0.1% formic acid) (70:30, v/v). The total run time was 5.0 min for each sample. The analytes was detected by mass spectrometry with electrospray ionization source in positive selected reaction monitoring mode. The precursor‐fragment ion reaction for ambroxol was m/z 378.9 → 263.8, and for IS was m/z 349.0 → 205.9. The linearity was established over the concentration range of 1.56–400.00 ng/mL. The inter‐day and the intra‐day precisions were all within 10%. A simple protein precipitation with methanol was adopted for sample preparation. The extraction recoveries of ambroxol and IS were higher than 90.80%. The validated method was successfully applied in pharmacokinetic study after oral administration of 90 mg ambroxol to 24 healthy volunteers. Copyright © 2008 John Wiley & Sons, Ltd.
An HPLC method for the determination and pharmacokinetic study of lehmannine in rat plasma
Authors: Zhao Gang , Du Wei , Wei Yuhui , Qin Hongyan , Wu Xinan
Published: May 2008

A high‐performance liquid chromatographic (HPLC) method for determining lehmannine (LMN) in rat plasma was developed for application in the pharmacokinetics study. The plasma was deproteinized with acetonitrile that contained an internal standard and was separated from the aqueous layer by adding sodium chloride. The HPLC assay was carried out using a VP‐ODS column at 40°C. The mobile phase was acetonitrile–0.02 mol/L ammonium acetate buffer–triethylamine (35:65:0.04, v/v/v). The flow rate was 1.0 mL/min. The detection wavelength was set at 220 nm. The method was used to determine the concentration–time profiles of LMN in the plasma following oral administration or bolus injection of LMN aqueous solution. The pharmacokinetic parameters of LMN were calculated for the first time by Drug and Statistics 1.0 program. Copyright © 2008 John Wiley & Sons, Ltd.
Determination of organic acids in urine by solid‐phase microextraction and gas chromatography–ion trap tandem mass spectrometry previous ‘in sample’ derivatization with trimethyloxonium tetrafluoroborate
Authors: Pacenti Marco , Dugheri Stefano , Villanelli Fabio , Bartolucci Gianluca , Calamai Luca , Boccalon Pierpaolo , Arcangeli Giulio , Vecchione Febe , Alessi Paolo , Kikic Ireneo , Cupelli Vincenzo
Published: May 2008

A method for the determination of the organic acids directly in the urine employing derivatization with trimethyloxonium tetrafluoroborate as a methylating agent and sequential extraction by head space and direct immersion/solid phase microextraction is reported. Furoic acid, hippuric acid, methylhippuric acid, mandelic acid, phenylglyoxylic acid and trans, trans muconic acid contained in urine and proposed by the American Conference of Governmental Industrial Hygienists as biological exposure indices were determined after a fast and economically convenient preparation step and sensitive gas chromatography–ion trap–mass spectrometry/tandem mass spectrometry analysis. Urine is rather a complex sample and hence the acquisition method required specific GC‐MS instrumentation capable of supporting the changeover, fully automated during a single chromatographic separation, from mass to tandem mass spectrometry and both chemical and electron ionization modes. The automation of the analytical method provides a number of advantages, including reduced analysis time for both routine analysis and method development, and greater reproducibility. The equilibrium and kinetics of this substances vs head space/direct immersion‐solid phase microextraction were investigated and evaluated theoretically. Copyright © 2008 John Wiley & Sons, Ltd.
Changes in IL‐8 release and intracellular content in DMSO‐differentiated HL‐60 cells after treatment with 4‐hydroxynonenal
Authors: Maggiora Marina , Rossi Maria Armida
Published: May 2008

4‐Hydroxynonenal (HNE), a chemotactic aldehyde produced by lipid peroxidation, has been shown to trigger exocytosis in HL‐60 cells induced to differentiate toward the granulocytic cell line by DMSO. In this work we studied HNE effects on the intracellular content of IL‐8 and its release in DMSO‐differentiated HL‐60 cells. Cell incubation at 37°C in the presence of 0.1 µM HNE induced a significant increase of IL‐8 release after 30 min; the degree of HNE‐induced IL‐8 secretion became quite strong after 1 h, whereas the intracellular content showed no statistically significant changes. By contrast, 1 µM HNE induced a low decrease of the chemokine release; however, the used HNE concentrations failed to increase the release of lactate dehydrogenase (LDH), a test used to assay cell viability. The addition of 0.1 µM IL‐8 to DMSO‐differentiated HL‐60 cells induced a strong increase of exocytosis, measured by β‐glucuronidase secretion. Exocytosis stimulation by IL‐8 was much higher than that given by the aldehyde; the addition of various HNE concentrations to cells incubated in the presence of IL‐8 decreased the secretion given by the cytokine alone. However, HNE‐induced exocytosis was likely to be a direct action of the aldehyde and was not mediated through the stimulation of IL‐8 release since HNE was unable to modify IL‐8 secretion during the short time of 10 min used in the exocytosis assay. Copyright © 2008 John Wiley & Sons, Ltd.
Calix[n]arene‐Based Glycoclusters: Bioactivity of Thiourea‐Linked Galactose/Lactose Moieties as Inhibitors of Binding of Medically Relevant Lectins to a Glycoprotein and Cell‐Surface Glycoconjugates and Selectivity among Human Adhesion/Growth‐Regulatory Galectins
Authors: André Sabine , Sansone Francesco , Kaltner Herbert , Casnati Alessandro , Kopitz Jürgen , Gabius Hans‐Joachim , Ungaro Rocco
Published: May 2008

Growing insights into the functionality of lectin–carbohydrate interactions are identifying attractive new targets for drug design. As glycan recognition is regulated by the structure of the sugar epitope and also by topological aspects of its presentation, a suitable arrangement of ligands in synthetic glycoclusters has the potential to enhance their avidity and selectivity. If adequately realized, such compounds might find medical applications. This is why we focused on lectins of clinical interest, acting either as a potent biohazard (a toxin from Viscum album L. akin to ricin) or as a factor in tumor progression (human galectins‐1, ‐3, and ‐4). Using a set of 14 calix[n]arenes (n=4, 6, and 8) with thiourea‐linked galactose or lactose moieties, we first ascertained the lectin‐binding properties of the derivatized sugar head groups conjugated to the synthetic macrocycles. Despite their high degree of flexibility, the calix[6,8]arenes proved especially effective for the plant AB‐toxin, in the solid‐phase model system with a single glycoprotein (asialofetuin) and with human tumor cells in vitro. The bioactivity of the calix[n]arenes was also proven for human galectins. Notably, selectivity for the tested tandem‐repeat‐type galectin‐4 among the three subgroups was determined at the level of solid‐phase and cell assays, the large flexible macrocycles again figuring prominently as inhibitors. Alternate and cone versions of calix[4]arene with lactose units distinguished between galectins‐1 and ‐4 versus galectin‐3 in cell assays. The results thus revealed bioactivity of galactose‐/lactose‐presenting calix[n]arenes for medically relevant lectins and selectivity within the family of adhesion/growth‐regulatory human galectins.
Separation and Purification of β‐Carotene from Chlorophyll Factory Residues
Authors: Huang M. , Xu Y.‐J. , Lv Q.‐L. , Ren Q.‐L.
Published: May 2008

A process for the separation and purification of β‐carotene from chlorophyll factory residues has been developed. By use of three‐step extractions using ethanol, hexane‐NaCl aqueous solution and hexane‐95 % methanol, β‐carotene was enriched up to 0.23 % with a recovery of 79.6 %. The performance and separation characteristics relevant to β‐carotene were measured on HZ816, H103, D4006, HZ801, X5, S8, AB8 and D301 resins. It was found that the non‐polar macroporous X5 resin offers the largest adsorption capacity among the tested adsorbents. The Langmuir and Freundlich adsorption models were applied to describe the multicomponent isotherms of the crude residue, and the experimental data fits best to the Freundlich isotherm. Dynamic adsorption and desorption tests were performed to optimize the β‐carotene separation process on a packed‐bed X5 column. The parameters for dynamic adsorption include a β‐carotene sample solution concentration of 174.5 μg/mL, processing volume of 5 BV, flow rate of 0.5 BV/h, and a temperature of 25 °C. The β‐carotene was eluted entirely from the column following treatment with a gradient elution of ethanol‐ether. The content in the product increased from 0.23 % to 2.03 %, with a recovery yield of 76.6 %. It was then recrystallized in chloroform‐ethanol to obtain a final crystalline product with a purity of 95 %.
Extraction and Purification of Bioproducts and Nanoparticles using Aqueous Two‐Phase Systems Strategies
Authors: Benavides J. , Aguilar O. , Lapizco‐Encinas B. H. , Rito‐Palomares M.
Published: May 2008

Aqueous Two‐Phase Systems (ATPS) is a primary recovery technique that has shown great potential for the efficient extraction and purification of high value biological compounds. The main advantages of this technique include scaling up feasibility, process integration capability and biocompatibility. In this review, the efficient use of ATPS for the extraction of proteins, genetic material, low molecular weight compounds, bioparticles, nanoparticles and cells is highlighted. The important role of ATPS in process integration, i.e., extractive conversion, extractive fermentation, cell disruption integrated with product recovery, and extractive purification, is discussed. A novel approach to protein molecular characterization combining ATPS and 2‐dimension electrophoresis (2‐DE) is introduced as a first step in the process development. Novel approaches for downstream processing using ATPS and dielectrophoresis are presented. Finally, trends concerning the application of ATPS strategies to address the future challenges of bioseparation are discussed.
Downstream Processing of Plasmid DNA for Gene Therapy and Genetic Vaccination
Authors: Voß C.
Published: May 2008

Plasmid DNA is used as a cloning vector to deliver recombinant genetic information into microorganisms. Since the 1990s, this principle has also been applied for the delivery of therapeutic genes in gene therapy and genetic vaccination. This non‐viral gene delivery is afflicted with fewer safety concerns in comparison to viral systems. Processes for the production of high‐quality plasmid DNA at multi‐ and kilogram scale are necessary to meet the needs of clinical trials as well as future therapeutics. Cell disruption, the separation of structurally‐related impurities and analytical techniques for process and quality control are the main challenges for bioengineering. This review summarizes the development in these fields over the past recent years.
Comment on Aspects of Chitosan Preparation
Authors: Leonhardt S. E. S. , Ondruschka B. , Ondruschka J.
Published: May 2008

The deacetylation of chitin was studied as a function of NaOH concentration, reaction time and temperature as determined by acid‐base titration. Deacetylation was performed by classical heating or under microwave irradiation. Microwave experiments were carried out to compare the results with selected examples from the Chinese literature. The maximum degree of deacetylation (88 %) was obtained after 30 min of classical heating (135 °C) in 50 wt % NaOH solution.
Chemical ant colony algorithm with supramolecular coefficient and multivariate calibration to calix[n]arenas(n = 4, 6, 8) supramolecular system
Authors: Ding Yaping , Wu Qingsheng , Su Qingde
Published: May 2008

A chemical ant colony algorithm (CACA) with supramolecular coefficient γ was put forward. It has successfully solved the multivariate calibration issue of the supramolecule analysis system, and realized the pure spectra fitting and the simultaneous determination of the calix[n]arenas(n = 4, 6, 8) in a multicomponent supramolecular system. The analyzing errors for calix[4, 6, 8]arenas through Chemical Ant Colony Algorithm with supramolecular coefficient γ are within ±3.75%. The errors by CACA are within ±7.50%. The former obviously excels the latter. Copyright © 2008 John Wiley & Sons, Ltd.
Application of QM simulations and multivariate analysis in the study of alkene reactivity in the zeolite H‐ZSM5
Authors: Gleeson Duangkamol
Published: May 2008

Reported herein are the results of an investigation into the effect of the extended framework of the zeolite ZSM‐5 on the reaction energetics and structures of (a) the physisorbed complex formed between the zeolite and six alkenes, (b) the corresponding chemisorbed alkoxide intermediate and (c) the transition states (TS) connecting the two. For this, quantum mechanical (QM) simulations of ZSM‐5 in the presence and absence of the zeolite framework have been employed. A 46T density functional theory (DFT) cluster model and a 3T:46T DFT:UFF ONIOM model are used to represent the former scenario and a simple 3T DFT cluster model for the latter. The structural implications of neglecting the zeolite framework have been rigorously compared using the multivariate statistical method principal components analysis (PCA). This method allows one to assess the correlated nature of the changes in structure along the reaction coordinate, for multiple different alkenes, in a facile, reliable way. Copyright © 2008 John Wiley & Sons, Ltd.
Fault detection and classification for a two‐stage batch process
Authors: Liu Jialin , Wong David Shan Hill
Published: May 2008

Multiway principal component analysis (MPCA) has been extensively applied to batch process monitoring. In the case of monitoring a two‐stage batch process, the inter‐stage variation is neglected if MPCA models for each individual stage are used. On the other hand, if two stages of reference data are combined into a large dataset that MPCA is applied to, the dimensions of the unfolded matrix will increase dramatically. In addition, when an abnormal event is detected, it is difficult to identify which stage's operation induced this alarm. In this paper, partial least squares (PLS) is applied to monitor the inter‐stage relation of a two‐stage batch process. In post‐analysis of abnormalities, PLS can clarify whether root causes are from previous stage operations or due to the changes of the inter‐stage correlations. This approach was successfully applied to a semiconductor manufacturing process. Copyright © 2008 John Wiley & Sons, Ltd.