bluuebunny/crossref_metadata_2025 huggingface dataset:
Modellierung des Wärmeübergangs beim Strahlsieden auf stark überhitzten Oberflächen
Authors: Timm W. , Weinzierl K. , Leipertz A.
Published: December 2003

No abstracts.
Wirbelschichtsprühgranulation – Neuartige Simulationssoftware zur Berechnung der Partikelgrößenverteilung, der Temperaturen und Gasbeladungen
Authors: Ihlow M. , Drechsler J. , Peglow M. , Henneberg M. , Heinrich S. , Mörl L.
Published: December 2003

No abstracts.
Kopplung zwischen Populationsbilanzen und CFD am Beispiel von Fällungsprozessen
Authors: Paschedag A.
Published: December 2003

No abstracts.
Integriertes Verfahren zur kontinuierlichen Hydrierung, Isolierung und Formgebung von Jojobaöl in überkritischem Kohlendioxid
Authors: Jourdan S. , Mohr T. , Vogel H.
Published: December 2003

No abstracts.
Visualisieren des Mikro‐ und Makromischens mit Hilfe zweier fluoreszierender und chemisch reagierender Farbstoffe
Authors: Kling K. , Mewes D.
Published: December 2003

No abstracts.
Aerosole und ihre technische Bedeutung
Authors: Heidenreich S. , Büttner H. , Ebert F.
Published: December 2003

Aerosole – gezielt erzeugt oder unerwünscht gebildet – treten in vielen technischen Prozessen auf. So werden zum Beispiel Aerosole gezielt erzeugt, wenn Produkte, die aus feindispersen Feststoffen bestehen, in einem Gasphasenprozess (im weitesten Sinn) hergestellt werden. Partikelbildung und ‐wachstum im Aerosolzustand prägen dabei die Größe, Form und Struktur der Partikel und damit entscheidend die Produkteigenschaften. Aerosole können sich auch unerwünscht in Prozessen bilden. Dies führt zur Verunreinigung von Prozessgasen oder Produkten beziehungsweise zu erhöhten Beladungen von Abluftströmen. Kann die unerwünschte Aerosolbildung nicht vermieden werden, müssen wirkungsvolle Abscheideverfahren eingesetzt werden. Effiziente Abscheider sind auch zur Gewinnung von Produktpartikeln aus der Gasphase notwendig. Ob gezielt erzeugt oder unerwünscht gebildet, Aerosole müssen hochauflösend erfasst und charakterisiert werden. Dies erfordert eine entsprechend leistungsfähige Aerosolmesstechnik. Der Beitrag vermittelt einen Überblick über die technische Bedeutung von Aerosolen.
Nassmahl‐Technologien mit Mahlkörpern und Lösungsansätze für Zentrifugenmühlen zur Herstellung nanoskaliger Suspensionspartikeln
Authors: Vock F.
Published: December 2003

Anhand der Entwicklung der Nassmahltechnologie mit Mahlkörpern in Rührwerksmühlen zum Zerkleinern und Dispergieren von organischen und anorganischen Feststoffpartikeln in Suspensionen mit Praxiserfahrung in der Chemie‐, Lackfarben‐ und Druckfarben‐Industrie wird gezeigt, dass ein weiterführender Entwicklungsschritt nötig ist, um die künftigen Anforderungen bei der Herstellung nanoskaliger Partikeln mit speziellen funktionalen Eigenschaften befriedigen zu können. Es werden Lösungsansätze beschrieben und erste Ergebnisse dargestellt.
MALDI‐TOF‐Massenspektrometrie: Risikoanalyse im Flug
Authors: Humeny Andreas
Published: December 2003

Durch ihre hohe Genauigkeit, molekulare Auflösung und Sensitivität ist die Matrix‐gestützte Laser Desorptions Ionisations Flugzeit Massenspektrometrie (MALDI‐TOF‐MS) eine sehr effiziente Methode zur Analyse von allen Biomolekülen wie Nukleinsäuren, Proteinen/Peptiden, Kohlenhydraten und Lipiden. Die MALDI‐TOF‐MS basierte Hochdurchsatz‐Genotypisierung von genetischen Heterogenitäten besitzt das Potential, eine Routinemethode zu werden. MALDI‐TOF‐MS kann für die Identifizierung von Proteinen und posttranslationalen Modifizierungen eingesetzt werden. Zusammenfassend ist die MAL‐DI‐TOF‐MS eine integrative Plattform‐Technologie in der Bioanalytik und Molekularen Medizin.
Die molekulare Welt des Lebensmittelgenusses: Auf den Geschmack gekommen
Authors: Schieberle Peter , Hofmann Thomas
Published: December 2003

Geruch und Geschmack sind stofflich objektivierbare Qualitätsparameter bei Lebensmitteln. Originär im Lebensmittel vorkommende bzw. beim Herstellungsprozess aus Vorläufern entstehende geruchs‐ bzw. geschmackaktive Verbindungen weisen z. T. extreme Unterschiede in ihrer Geruchs‐ bzw. Geschmackswirksamkeit auf. Anhand verschiedener Beispiele wird der Einsatz aktivitätsorientierter Screeningverfahren zur Entschlüsselung wichtiger originärer Geruchs‐ und Geschmacksstoffe von Lebensmitteln vorgestellt. Diese als „Molekulare Sensorik”︁ bezeichneten Techniken haben kürzlich zur Identifizierung sehr potenter Naturstoffe mit interessanten sensorischen Eigenschaften geführt. Solche sensorisch aktiven Biomoleküle sind zudem gute Marker zur gezielten Steuerung industrieller Lebensmittelproduktionsprozesse, um optimale Geschmacksprofile zu erhalten.
Membranständige Ionenkanäle
Authors: Koert Ulrich
Published: December 2003

Die schwedische königliche Akademie der Wissenschaften hat den Nobelpreis des Jahres 2003 in Chemie zu gleichen Teilen an Peter Agre und Roderick MacKinnon vergeben. Sie wurden für ihre Entdeckungen bezüglich der Kanäle in Zellmembranen ausgezeichnet.
Supraleiter‐ und Supraflüssigkeiten
Authors: Huebener Rudolf
Published: December 2003

Die Königlich Schwedische Akademie der Wissenschaften vergab in diesem Jahr den Physik‐Nobelpreis zu gleichen Teilen an Aleksej Abrikossow, Witalij Ginsburg und Anthony Leggett für ihre „pionierhaften Beiträge zur Theorie der Supraleiter und Supraflüssigkeiten.”︁
Chemische Kampfstoffe, Vergangenheitsbewältigung und aktuelle Aufgabe, Teil 1
Authors: Hildebrandt Henry
Published: December 2003

Chemische Kampfstoffe sollten der Vergangenheit angehören [1], doch ihre Entsorgung gestaltet sich schwierig [2], zumal moderne Kampfgase seit dem ersten Weltkrieg häufig benutzt wurden — und leicht herzustellen sind [3].
Lithium‐Ionen‐Akkus
Authors: Borchard‐Tuch Claudia
Published: December 2003

Beweglichkeit benötigt Energie. Kein Handy, Laptop oder Walkman kommt ohne leistungsfähige Batterien aus. Der Höhepunkt der Entwicklung zeigt sich derzeit in den Lithium‐Ionen‐Akkus, die pro Zelle bis zu 5 Volt liefern und über 1000 Mal wieder aufladbar sind.
Chemie — Augen — Blicke
Authors: Hirche Christina , Kreysa Gerhard
Published: December 2003

Vom 18. bis 24. Mai 2003 wurde anlässlich der ACHEMA und des Jahres der Chemie auf dem Frankfurter Messegelände auf etwa einem Kilometer Länge die größte Schülergalerie der Welt mit etwa 1.000 Bildern zum Thema Chemie präsentiert.
Dynamics of Photoinduced Electron‐Transfer Processes in Fullerene‐Based Dyads: Effects of Varying the Donor Strength
Authors: Thomas K. George , Biju V. , Kamat Prashant V. , George M. V. , Guldi Dirk M.
Published: December 2003

Two classes of fullerene‐based donor–bridge–acceptor (D–B–A) systems containing donors of varying oxidation potentials have been synthesized. These systems include fullerenes linked to heteroaromatic donor groups (phenothiazine/phenoxazine) as well as substituted anilines (p‐anisidine/p‐toluidine). In contrast to the model compound, an efficient intramolecular electron transfer is observed from the fullerene singlet excited state in polar solvents. An increase in the rate constant and quantum yield of charge separation (kcs and Φcs) has been observed for both classes of dyads, with decrease in the oxidation potentials of the donor groups. This observation indicates that the rates of the forward electron transfer fall in the normal region of the Marcus curve. The long‐lived charge separation enabled the characterization of electron transfer products, namely, the radical cation of the donor and radical anion of the pyrrolidinofullerene, by using nanosecond transient absorption spectroscopy. The small reorganization energy (λ) of C60 coupled with large negative free energy changes (‐ΔG°) for the back electron transfer places the back electron process in the inverted region of Marcus curve, thereby stabilizing the electron transfer products.
Experimental and Computational Investigations of the Properties of Fluorinated Single‐Walled Carbon Nanotubes
Authors: Bettinger Holger F.
Published: December 2003

Fluorination of single‐walled carbon nanotubes by reaction with elemental fluorine at elevated temperatures provides fluorinated single‐walled carbon nanotubes (F‐SWNT), which have the highest degree of functionalization (up to F/C=1/2) of any derivatized carbon‐nanotube material reported to date. Also, F‐SWNTs have received more scrutiny than any other functionalized carbon nanotubes. This Minireview covers experimental and computational investigations of F‐SWNTs with a focus on the nature and the strength of the C–F linkage.
Stability of surface waves at magnetized plasma – metal interface
Authors: Akimov Yu. A. , Azarenkov N. A. , Olefir V. P.
Published: December 2003

The stability of high‐frequency potential surface waves at a dense magnetized plasma – metal interface with respect to a low‐frequency plasma density modulation is studied in the point of view of the surface waves control. The discussion is addressed to the situation, when an external steady magnetic field is directed perpendicularly to the interface. The nonlinear interaction process of the high‐frequency surface wave, its satellites and the low‐frequency plasma density perturbation is investigated. It is shown that the low‐frequency plasma density perturbation can be represented as a superposition of forced waves of surface and volume types and can lead to an additional attenuation of the surface waves. This attenuation arises when the surface wave amplitude exceeds the threshold value. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Distributed location estimation method for mobile terminals based on SOM algorithm
Authors: Asakura Shigeru , Umehara Daisuke , Kawai Makoto
Published: December 2003

Ad hoc networks have excellent capabilities for data transmission in an environment with an incomplete communications infrastructure, and in mobility and portability of terminals. Routing protocols between terminals in an ad hoc network can be broadly divided into location‐aware routing, based on location information on the terminals, and non‐location‐aware routing, which is not based on location information. In the former, routing can be made accurate and easy by effectively utilizing location information. Hitherto, the use of the global positioning system (GPS) has been most often treated as the means of acquiring terminal location information. However, in location estimation by GPS, electromagnetic waves from multiple location estimation satellites must be received, and the method cannot be applied effectively in an environment in which that condition is not satisfied. This paper proposes the following method of location estimation. Fixed access points whose absolute locations are already known are placed in the network. Then, by using self‐organizing maps (SOM), the mutual location information among the terminals is organized, and the location of the home terminal is successively inferred. The feasibility and accuracy of estimation in the proposed method are examined by a computer simulation. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(4): 73–81, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10098
Fast fading compensation schemes for OFDM transmission
Authors: Yoshida Haruhito , Maehara Fumiaki , Sasamori Fumihito , Takahata Fumio
Published: December 2003

A decision feedback compensation scheme that successively updates the channel estimate based on the decision values of the channel estimate (CE) symbols inserted in the frame header and the symbols in the data section is an effective fading compensation scheme for orthogonal frequency‐division multiplexing (OFDM). However, when rapid phase fluctuations are produced as the received signal level drops in the frame, errors are propagated in successive symbols, and the accuracy of the fading compensation severely degrades. In this paper, we propose a fading compensation scheme for information symbols that places CE symbols in the last section in addition to those in the header section in one frame, which should lessen the error propagation effect. Specifically, we propose a direction‐controlled unidirectional fading compensation scheme that adaptively controls the compensation direction based on the instantaneous signal‐to‐noise ratio (SNR) estimated from the CE symbols on both ends for each subcarrier and a bidirectional fading compensation scheme that detects drops in the received signal level in a frame and switches the direction of the fading compensation. The results of the performance evaluation showed that the performance was improved by the former scheme in a fast fading environment, and a significant improvement in the transmission performance was possible by applying the latter scheme. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(4): 35–44, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10130
A proposal of geographical routing protocols for location‐aware services
Authors: Yamazaki Kosuke , Sezaki Kaoru
Published: December 2003

Rapid advances in recent device technologies continue to create ubiquitous computing environments that have wireless devices everywhere in the surroundings. Positioning devices such as the Global Positioning System (GPS) and pseudolite continue to decrease in price and wireless devices containing them can determine the location of the device itself. Given this background, providing services based on the location information of a device group, in other words, location‐aware services, is currently an active topic. The location‐aware services being widely researched today provide guide systems to users. A typical service is Intelligent Transport Systems (ITS). However, these services are not available in an environment where special positioning devices cannot be used, and the user must switch to another service. Existing services have the drawback of architectures that are greatly affected by the user's environment. Thus, in this paper, we propose seamless location‐aware services that will improve on these conventional services. We present the problems of using existing methods as the routing protocol, which is an element technology of these services; propose and evaluate a method better suited to these services; and verify its effects by a computer simulation. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(4): 26–34, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10138
A multichannel media access control protocol for multihop wireless networks with guaranteed functions
Authors: Mizuno Kohei , Katayama Minoru , Nakayama Masayoshi , Suda Hirohito
Published: December 2003

In this paper, we propose a multichannel Medium Access Control (MAC) protocol based on the Point Coordination Function (PCF) stipulated in the IEEE 802.11 standard in order to guarantee the end‐to‐end bandwidth in a multihop wireless network. In the proposed protocol, each wireless terminal is equipped with multiple wireless interfaces and assigns a wireless channel to each wireless interface. Each wireless interface autonomously determines whether to operate in the master mode as the parent terminal, in the slave mode as a child terminal, or in the silent mode as a transmission disabled terminal, and builds a parent‐child relationship with each wireless link. Since this enables the use of the PCF at each wireless link and guarantees the bandwidth, the end‐to‐end bandwidth can be guaranteed in a multihop wireless network. We evaluate the performance of the proposed protocol in computer simulations and demonstrate improved throughput, delay, and packet loss rate compared to the conventional Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol. We also demonstrate that the bandwidths for bandwidth‐guaranteed packets are guaranteed even when traffic mixing conventional bandwidth‐guaranteed packets and best‐effort packets are present on the network. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(4): 16–25, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10139
Biodiesel stability under commercial storage conditions over one year
Authors: Bondioli Paolo , Gasparoli Ada , Della Bella Laura , Tagliabue Silvia , Toso Guido
Published: December 2003

Results obtained from a long‐term storage study using eleven different biodiesel samples are presented. Samples prepared from several feedstocks using different manufacturing technologies (with or without biodiesel distillation), some containing an antioxidant additive, were stored in 200 l drums. These were periodically monitored during the complete storage period by analysis of fifteen different properties.

Several properties do not show any significant change during storage, while others such as viscosity, peroxide value and more dramatically, Rancimat Induction Period demonstrated changes related to the nature of the starting product.

A parallel test, carried out in simulated wrong storage conditions (occasional shaking promoting intimate contact between biodiesel and air oxygen) lead to some strong changes in biodiesel composition and can be used as a guide for devising biodiesel production set‐up, storage and distribution chain.
Enzymatic production of fatty acid alkyl esters with a lipase preparation from Candida sp. 99‐125
Authors: Deng Li , Tan Tianwei , Wang Fang , Xu Xuebing
Published: December 2003

A lipase preparation developed from Candida sp. 99‐125 was used for fatty acid alkyl ester synthesis by both enzymatic esterification of fatty acids, and transesterification of oils and fats. The lipase preparation was chosen based on screening of lipases from commercial sources as well as those produced in the laboratory. The effects of enzyme dosage, solvent types, water absorbent additions, inhibition of short‐chain alcohols, alcohol and acid types, molar ratio of substrates, and reusability of the lipase preparation in esterification were studied. Degree of esterification between oleic acid and methanol under optimal conditions reached 92%. Purity of the methyl ester after washing with water and distillation was 98%. Half‐life of the lipase preparation was calculated to be approximately 340 h. For transesterification of rapeseed oil with the same lipase preparation, the amount of methanol and mode of methanol addition to the reaction were also conducted. Transesterification of the oil with stepwise methanol addition reached 83% after 36 h reaction time.
13‐Phenyltridec‐9‐enoic and 15‐phenylpentadec‐9‐enoic acids in Arum maculatum seed oil
Authors: Christie William W.
Published: December 2003

The seed oil of Arum maculatum has been found to contain 13‐phenyltridec‐9‐enoic (0.4%) and 15‐phenyl‐pentadec‐9‐enoic (1%) acids, detected by gas chromatographymass spectrometry of the picolinyl ester and related derivatives.
The development and application of novel vegetable oils tailor‐made for specific human dietary needs
Authors: Sakurai Hidetoshi , Pokorný Jan
Published: December 2003

Conventional edible oils, such as sunflower, safflower, soya bean, rapeseed (canola) oils, were modified to obtain high‐oleic, low‐linoleic or even low‐linolenic oils. The aim was to develop salad, cooking and frying oils, that are very stable against lipid peroxidation. They are also suitable for margarine blends, as additives to cheeses and sausages, or even as feed components. Oils containing higher amounts of medium‐chain length or long‐chain polyunsaturated fish oil fatty acids are suitable as special dietetic oils or as nutraceuticals. High‐stearic oils are designed as trans‐fatty acid‐free substitutes for hydrogenated oils. New tailor‐made (designer) oils are thus a new series of vegetable oils suitable for edible purposes, where conventional oils are not suitable.
Georgetown University Fuel Cell Transit Bus Program
Authors: Romano S. , Larkins J.T.
Published: December 2003

Georgetown University (GU) has been at the forefront in the development of transportation fuel cells for over eighteen years. GU has been involved in the development, demonstration and testing of several fuel cell power plants and vehicles, including three 30‐foot transit buses and two 40‐foot transit buses. All of these vehicles are still operational. GU rolled out a 40‐foot fuel cell powered transit bus May 1998. This electric bus is powered by a 100 kW Phosphoric Acid Fuel Cell (PAFC) manufactured by UTC Fuel Cells, LLC. A second 100 kW Proton Exchange Membrane Fuel Cell (PEMFC) power plant has been fabricated by Ballard Transportation Business Unit and has been integrated into a second 40‐foot transit bus platform. This is the world′s largest PEMFC power plant capable of operating on liquid methanol; it rolled out in December, 2001. The GU program is the only one of its kind that is addressing the commercialization of the easily refueled and longer‐range, liquid‐fueled fuel cell buses. As a hydrogen carrier, methanol greatly exceeds the vehicular weight percent storage targets for hydrogen set by the US Department of Energy (DOE). Coal, an abundant US domestic fuel, can be used to produce methanol. The potential to make domestic coal the feedstock for transportation fuel cannot be ignored. This offers a realistic approach to true energy independence. The GU Fuel Cell Powered Transit Bus Program is supported by a grant from the Federal Transit Administration (FTA).
Fuel Cell Vehicle Simulation – Part 2: Methodology and Structure of a New Fuel Cell Simulation Tool
Authors: Hauer K.H. , Moore R.M.
Published: December 2003

This paper is the second part of a three part series. In Part I existing publicly available models for fuel cell vehicle (FCV) analysis and simulation were analyzed and the strengths and weaknesses of these models were identified. In this paper a fuel cell vehicle simulation program (and the methodology behind it) is introduced that overcomes the shortcomings of the previously benchmarked models. Specifically this new fuel cell model: (i)explicitly recognizes the dynamic interaction between the fuel cell system, drive train and optional additional energy storage via electrical and mechanical feedback; (ii) separates the controls from the physical component models (allowing for rapid prototyping techniques); (iii) is strictly modular and follows the vehicle physics as close as possible. Every block can be assigned to a single piece of hardware or control software in the vehicle). The third paper of this series will describe the modeling of individual fuel cell system components and how they are integrated into the overall vehicle model described in this paper.
A longitudinal study of neuropsychological change in individuals with Parkinson's disease
Authors: Azuma Tamiko , Cruz Robyn F. , Bayles Kathryn A. , Tomoeda Cheryl K. , Montgomery E. B.
Published: December 2003

Objectives

Neuropsychological changes in individuals with Parkinson's disease (PD) were studied longitudinally.

Methods

Sixty‐nine idiopathic PD patients, with Mini‐Mental State Examination (MMSE) scores falling within normal range, and 37 elderly control participants were given neuropsychological tests twice approximately two years apart.

Results

The PD group performed poorer than the control group on Semantic Fluency, Letter Fluency, Modified Wisconsin Card Sorting Task, and Block Design at test time 1. Two years later, the PD group showed significant decline in Semantic and Letter Fluency. A subset of 12 PD patients declined in mental status by second testing (>4 MMSE points). Cox proportional‐hazards models were used to see if any baseline measures were associated with relative risk of decline in mental status. In the final model, Repetition performance and Age were significantly associated with cognitive decline.

Conclusions

Consistent with previous studies, executive function tasks were those most susceptible to disease progression. Copyright © 2003 John Wiley & Sons, Ltd.
Use of psychotropics among home‐dwelling nondemented and demented elderly
Authors: Hartikainen Sirpa , Rahkonen Terhi , Kautiainen Hannu , Sulkava Raimo
Published: December 2003

Objective

To describe the use of psychotropics in the nondemented and demented elderly.

Participants

The home‐dwelling elderly (n=523) among the random sample of 700 subjects from the total population of individuals aged 75 years or more in 1998 and living in the city of Kuopio, Finland.

Methods

A trained nurse interviewed the participants about their health and current use of medicines. A geriatrician performed clinical examinations and diagnosed diseases. Dementia and depression were diagnosed according to the DSM‐IV criteria.

Results

The demented subjects used more medicines of all kinds (p<0.01), and especially more psychotropics than the nondemented (p<0.001). One in four demented subjects, compared to one in ten nondemented ones used at least two psychotropics (p<0.01). The demented subjects used antipsychotics six times more often than the nondemented ones (p<0.001). Among the nondemented subjects, one out of two antipsychotics users was suffering from depression according to DSM‐IV criteria. Three out of four persons who had dementia with Lewy bodies were using psychotropics. Persons with moderate dementia were more commonly using all kinds of psychotropic preparations especially, antipsychotics three times more commonly than persons with mild or severe dementia.

Conclusion

Psychotropics, especially antipsychotics, are commonly used in the treatment of both nondemented and demented elderly, even without proper indication. Physicians need more training about the appropriate use of psychotropics to minimize their adverse effects. Copyright © 2003 John Wiley & Sons, Ltd.
Characterization of two‐photon excitation fluorescence lifetime imaging microscopy for protein localization
Authors: Chen Ye , Periasamy Ammasi
Published: December 2003

Two‐photon excitation fluorescence resonance energy transfer (2P‐FRET) imaging microscopy can provide details of specific protein molecule interactions inside living cells. Fluorophore molecules used for 2P‐FRET imaging have characteristic absorption and emission spectra that introduce spectral cross‐talk (bleed‐through) in the FRET signal that should be removed in the 2P‐FRET images, to establish that FRET has actually occurred and to have a basis for distance estimations. These contaminations in the FRET signal can be corrected using a mathematical algorithm to extract the true FRET signal. Another approach is 2P‐FRET fluorescence lifetime imaging (FLIM). This methodology allows studying the dynamic behavior of protein‐protein interactions in living cells and tissues. 2P‐FRET‐FLIM was used to study the dimerization of the CAATT/enhancer binding protein α (C/EBPα). Results show that the reduction in donor lifetime in the presence of acceptor reveals the dimerization of the protein molecules and also determines more precisely the distance between the donor and acceptor. We describe the development and characterization of the 2P‐FRET‐FLIM imaging system with the Bio‐Rad Radiance2100 confocal/multiphoton microscopy system. Microsc. Res. Tech. 63:72–80, 2004. © 2003 Wiley‐Liss, Inc.
Performances of high numerical aperture water and oil immersion objective in deep‐tissue, multi‐photon microscopic imaging of excised human skin
Authors: Dong Chen‐Yuan , Yu Betty , Kaplan Peter D. , So Peter T.C.
Published: December 2003

Multi‐photon fluorescence microscopy (MPFM) is a powerful technique for imaging scattering, biological specimens in depth. In addition to the sectioning effect generated by the point‐like excitation volume, the near‐infrared wavelengths used for multi‐photon excitation allow deeper penetration into optically turbid specimens. In physiological specimens, the optical properties such as the scattering coefficients and refractive indices are often heterogeneous. In these specimens, it is not clear which type of immersion objective can provide optimized images in‐depth. In particular, in‐depth dermatological imaging applications using MPFM requires such optimization to obtain qualitative and quantitative information from the skin specimens. In this work, we address this issue by comparing the performances of two common types of high numerical aperture (NA) objectives: water‐immersion and oil‐immersion. A high‐quality water‐immersion objective (Zeiss, 40× C‐Apochromat, NA 1.2) and a comparable oil‐immersion objective (Zeiss, 40× Fluar, NA 1.25) were used for in‐depth imaging of autofuorescent excised human skin and sulforhodamine B treated human skin specimens. Our results show that in the epidermal layers, the two types of immersion objectives perform comparably. However, in the dermis, multi‐photon imaging using the oil immersion objective results in stronger fluorescence detection. These observations are most likely due to the degraded point‐spread‐function (PSF) caused by refractive index mismatch between the epidermis and the dermis. Microsc. Res. Tech. 63:81–86, 2004. © 2003 Wiley‐Liss, Inc.
Qualitative assessment of rhizodeposits in non‐sterile soil by analytical pyrolysis
Authors: Kuzyakov Yakov , Leinweber Peter , Sapronov Dmitri , Eckhardt Kai‐Uwe
Published: December 2003

Estimation of the amount of root exudates and simultaneous identification of their composition in non‐sterile soil is a challenging objective in rhizosphere research. We coupled 3 methods: (1) labeling of corn in 14CO2 atmosphere to separate root‐derived and soil‐derived organic substances in the rhizosphere, (2) a previously developed leaching method to collect rhizodeposits, and (3) pyrolysis field ionization mass spectrometry (Py‐FIMS) to investigate the molecular‐chemical composition of rhizodeposits. Eluted rhizodeposits accounted for 2.8 % (Loam) and 0.97 % (nutrient solution in quartz sand) of recovered 14C and showed clear differences in composition between the growth substrates. The 14CO2 evolved mostly by root respiration accounted for 3.5–4.0 % without significant differences according to growth substrate or diurnal dynamics. Principal component analysis of the Py‐FI mass spectra of leachates showed a clear diurnal dynamics of the amount and the composition of corn rhizodeposits collected during day‐time and night‐time. Differences originated mostly from signals assigned to carbohydrates, sterols, and peptides. This approach is recommended for forthcoming studies of rhizodeposition in different soil substrates, crops grown, and time‐series of exudate sampling.
Retention of dissolved organic matter by illitic soils and clay fractions: Influence of mineral phase properties
Authors: Kahle Maren , Kleber Markus , Jahn Reinhold
Published: December 2003

The dependency of the retention of dissolved organic carbon (DOC) on mineral phase properties in soils remains uncertain especially at neutral pH. To specifically elucidate the role of mineral surfaces and pedogenic oxides for DOC retention at pH 7, we sorbed DOC to bulk soil (illitic surface soils of a toposequence) and corresponding clay fraction (< 2 μm) samples after the removal of organic matter and after removal of organic matter and pedogenic oxides. The DOC retention was related to the content of dithionite‐extractable iron, specific surface area (SSA, BET‐N2 method) and cation exchange capacity (pH 7). The reversibility of DOC sorption was determined by a desorption experiment. All samples sorbed 20–40 % of the DOC added. The DOC sorption of the clay fractions explained the total sorption of the bulk soils. None of the mineral phase properties investigated was able to solely explain the DOC retention. A sorption of 9 to 24 μg DOC m–2 indicated that DOC interacted only with a fraction of the mineral surface, since loadings above 500 μg m–2 would be expected for a carbon monolayer. Under the experimental conditions used, the surface of the silicate clay minerals seemed to be more important for the DOC sorption than the surface of the iron oxides. The desorption experiment removed 11 to 31 % of the DOC sorbed. Most of the DOC was strongly sorbed.
Can ATP be measured in soils treated with industrial oily waste?
Authors: Wen Guang , Voroney R. Paul , McGonigle Terry P. , Inanaga Shinobu
Published: December 2003

Soil samples were collected from a field with a long‐term (10 yr) oily wastewater application history, containing 70 mg g–1 of oil and grease and an accumulation of heavy metals, and also from a short‐term (1 yr) wastewater application involving different rates of waste, tillage, and nitrogen (N) fertilization. Prior to ATP extraction, the soils were incubated at 22 °C and a water potential of –60 kPa for 21 d and 2 d for the long‐ and short‐term trials, respectively. The light emitted from the bioluminescence reaction was partly quenched in the extract of steam‐sterilized long‐term waste‐treated soil, and curvilinearly responded to the addition of ATP at concentrations higher than 4 ng ATP per assay in contrast to the linear response from the pure extractant and the extract of control soil. Calibration curves developed from the extracts of steam‐sterilized soils were used for calculating ATP in that given soil. ATP determined in the long‐term treated soil was as high as 3201 ng (g soil)–1. Still, residual oil to ATP concentration ratio was about an order of magnitude higher in the long‐ than in the short‐term waste‐treated soil, reflecting the accumulation of recalcitrant material. In the short‐term treated soils, ATP ranged from 355 to 760 ng (g soil)–1 and responded to the rate of waste application, tillage, and fertilization. The use of ATP measurement has potential for assessing land management effects and developing tillage and fertilization recommendations for enhanced biodegradation of the oil waste.
Minirhizotron quantification of soybean root growth as affected by reduced A horizon in soil
Authors: Yang John , Hammer R. David , Blanchar Robert W.
Published: December 2003

Shallow soil A horizon (topsoil) caused by soil erosion and soil movement from cultivation is known to reduce soil and crop productivity. The reduction may be related to limitation of root growth. A field study was conducted to investigate the effects of topsoil thickness on distributions of root density and growth. Soybeans [Glycine max (L.) Merr.] were grown on plots of Mexico silt loam (fine, montmorillonitic, mesic Mollic Endoaqualfs) with topsoil thicknesses of 0, 12.5, 25.0, and 37.5 cm above the Bt horizons. Root density was measured 60 and 90 days after planting using a minirhizotron video‐camera system. Root density was significantly reduced as topsoil thickness decreased from 37.5 to 0 cm. Mean density and net change of the density across profile between 30 and 60 days of growth had a linear function of topsoil thickness. The reduction and lower activity induced by shallow topsoil were attributed to detrimental properties in the Bt horizons. Root distribution pattern and rooting depth were not significantly affected by topsoil thickness. The roots appeared to be accumulated on the upper layers of the Bt horizons. Roots growing in thicker topsoil were more active than roots growing without topsoil. High soil moisture content during the growing season may mitigate the detrimental effects of shallow topsoil, inhibit root penetration, and enhance root activity.
Enzyme activities in semiarid soils under conservation reserve program, native rangeland, and cropland
Authors: Acosta‐Martínez Veronica , Klose Susanne , Zobeck Ted M.
Published: December 2003

There is limited knowledge of biochemical processes in low carbon content soils of semiarid regions under different land use and management. This study investigated several enzyme activities of C, N, P, and S transformations in semiarid soils with different clay (10–21 %) and sand (59–85 %) contents that were under conservation reserve program (CRP), native rangeland (NR), and cropland (CL) under sunflowers (Eriophyllum ambiguum (Gray)), continuous cotton (Gossypium hirsutum L.), or in rotations with wheat (Triticum aestivum L.) or sorghum (Sorghum bicolor L.) in West Texas, USA. Soils under CRP and NR showed higher total C and N contents than cultivated soils under continuous cotton, but soil pH (6.7–8.4) was not affected by the management or land use studied. The activities of β‐glucosidase, β‐glucosaminidase, arylamidase, acid and alkaline phosphatase, phosphodiesterase, and arylsulfatase (mg product (kg soil)–1 h–1) were lower in CL under continuous cotton compared to cotton in rotation with other crops, CRP, and NR. The enzyme activities were also lower when compared to soils from other regions. Linear regression analyses indicated positive correlations between enzyme activities and total C (r values up to 0.96, P < 0.01). There was a positive relationship between enzyme activities and total N, but soil pH showed the opposite trend. Enzyme activities were significantly intercorrelated with r values up to 0.98 (P < 0.001). The specific enzyme activities (mg product (g organic C)–1) were lower in continuous cotton in comparison to the uncultivated soils (i.e., NR and CRP) reflecting differences in organic matter quantity and quality due to cultivation. Among the enzymes studied, the specific activities of β‐glucosidase and arylamidase showed a more pronounced decrease with increasing soil depth. In general, soils under CRP or wheat‐cotton rotations revealed higher enzyme activities than soils under the common agricultural practice for these regions, i.e., continuous cotton under conventional tillage.
Suitability of the ESS laboratory method to determine the equilibrium soil solution composition of agricultural soils, and suggestions for simplification of the experimental procedure
Authors: Matschonat Gunda , Ingwersen Joachim , Streck Thilo
Published: December 2003

The proper selection of the background electrolyte is of special importance studying element availability and mobility in the laboratory. The determination of the background solution composition can be done with the equilibrium soil solution method ESS (Matschonat and Vogt, 1997). The ESS method is a procedure to find out a salt solution of major cations and anions that does not undergo changes in its composition when brought into contact with a specific soil sample. This composition is experimentally approximated in an iterative procedure until certain quality criteria are fulfilled. We tested if the ESS method, which was developed for forest soils, can successfully be applied also to agricultural soils. The solution composition was confirmed by an independent method. We used samples of a glasshouse and an arable loess soil. Because the ESS method is relatively time and work consuming, we tested modifications which should simplify the procedure: the use of dried and frozen samples instead of field fresh soil, an approximation according to the solution's electric conductivity only, and the modeling of cation exchange to omit iteration steps. The ESS method caused slight overestimation (10–25 %) in cation concentrations, but in general, these were well met. Individual anion concentrations, however, were not buffered in this soil and could not unequivocally be determined. We recommend to adjust the anion concentrations in the ESS procedure according to their proportions in an initial water extract. As ion concentrations are functions of the soil : solution ratio, any method based on addition of water to the soil, like the so‐called soil saturation extract (Germany: Bodensättigungsextrakt), runs a risk to seriously underestimate ion concentrations at field conditions. The ESS method may therefore be especially well suited for soils with a low water content. The use of frozen soil gave good results and the omission of iteration steps by cation exchange modeling was promising and will be explored with the aim to operationalize it in forthcoming work.
Improved separation and quantitative determination of hydrocarbon types in gas oil by normal phase high‐performance TLC with UV and fluorescence scanning densitometry
Authors: Matt Muriel , Galvez Eva M. , Cebolla Vicente L. , Membrado Luis , Bacaud Robert , Pessayre Stephanie
Published: December 2003

Improved methods for separation and quantitative determination of hydrocarbon types from gas oil have been developed, which were based on high‐performance thin‐layer chromatography with ultraviolet and fluorescence scanning densitometry using horizontal elution. One of the methods allows the separation, detection, and determination of alkanes and naphthenes to be carried out, using berberine‐impregnated silica gel HPTLC plates, elution with n‐hexane, and berberine‐induced fluorescence detection at 365 nm. Another developed method allows total aromatics to be determined using silica gel HPTLC plates by elution with n‐hexane and acetone, and UV detection. In turn, PACs over three aromatic rings can be determined on either silica gel or caffeine‐impregnated silica gel HPTLC plates, elution with n‐hexane, and selective detection using native fluorescence at 365 nm. Concentrations lower than 5 wt% can be determined using this technique. In addition, a technique for an efficient, baseline‐resolved separation of a gas oil according to the number of aromatics rings (mono + di‐, tri‐, and polyaromatic compounds with more than three rings) is presented here. This technique involves a multistep elution on a mixed (silica gel and caffeine‐impregnated silica gel HPTLC plate) using a counter‐elution device, and UV detection.
Quantitative extraction of sulfonamides in meats by supercritical methanol‐modified carbon dioxide: A foray into real‐world sampling
Authors: Arancibia Verónica , Valderrama Mauricio , Rodriguez Pía , Hurtado Francisco , Segura Rodrigo
Published: December 2003

Optimizing operational parameters and obtaining the highest possible recovery are two of the major objectives to be attained when any extraction process is performed on a real sample in which the true analyte concentration is unknown. Sulfadiazine (SDZ), sulfamerazine (SMR), and sulfamethazine (SMZ) were extracted from real samples of chicken liver, beef liver, and pig kidney, using methanol‐modified supercritical CO2. The optimum extraction parameters were found to be 17.237 MPa and 160°C for two of the three analytes; SMZ, on the other hand, was completely extracted at 120°C. Under these conditions of high temperature, high amounts of modifier (3.0 mL of methanol in a 10‐mL extraction vessel) and low pressure, all three sulfonamides (SAs) were shown to be quantitatively extracted from spiked samples from domestic animals which had not been given sulfonamides. Under the same conditions, meat samples of commercial origin were analyzed. These results were compared with those obtained by conventional extraction methods. Almost all the meat samples contained sulfa drug residue levels far exceeding the current tolerance levels allowed for most sulfonamides. Eighteen of thirty samples contained at least one of the three sulfonamides, and seven of these samples contained from 1.1 to 4.2 mg kg–1 of SMZ. The SAs were quantified by HPLC with UV absorbance and amperometric detection.
Chromatographic characterization of high‐boiling petroleum fractions
Authors: Sharma Brajendra K. , Sarowha Sukh Lal S. , Bhagat Shib D.
Published: December 2003

Detailed investigation of solvent‐separated fractions of petroleum vacuum residues is necessary for understanding the separation mechanism using different solvents and to prepare better feedstocks for secondary conversion processes. The efficiency of different solvents to remove polars and insolubles from vacuum residues (of two Indian crude oils) has been studied. The solvents used were n‐heptane, n‐hexane, and n‐pentane (non‐polar) and ethyl acetate (polar). Soluble fractions were characterized for hydrocarbon group type analysis using high performance liquid chromatography (HPLC), average molecular weights using size exclusion chromatography (SEC), and boiling point distribution using high temperature gas chromatography (HTGC). Method development for HPLC analysis involved the study of parameters such as columns, solvent polarity, detectors, model compounds study, calibration, flow, and solvent gradient programming. The study demonstrated that ultimate soluble fractions have the least content of polar structures of the kind which can cause problems, during cracking and are least prone to cracking. The HPLC, SEC, and simulated distillation (SIMDIS) methods developed and standardized are simple, accurate, and suitable for the rapid assay needed for quick compositional surveys.
Performance of an aqueous two‐phase‐based countercurrent chromatographic system for horseradish peroxidase purification
Authors: Magri María L. , Cabrera Rosa B. , Miranda María V. , Fernández‐Lahore Héctor M. , Cascone Osvaldo
Published: December 2003

Countercurrent chromatography (CCC) purification of horseradish peroxidase (HRP) from Armoracia rusticana root extracts was achieved by employing polymer‐phosphate aqueous two‐phase systems (ATPS). By using preparative columns at 1000 rpm, a 25–30% retention of the top phase of an ATPS composed of 10% w/w PEG 1540 and 14.8% w/w phosphate – with added 2 mol/kg sodium chloride – was obtained. The retention level was stable during the standard separation running time (4 h). Horseradish root extract samples were injected into the system (10–25 mL; 200–250 U/mL peroxidase; 2.0–4.0 mg/mL total protein). Retention of HRP in the CCC “column” during the chromatographic run was attained in the selected ATPS, where the partition coefficient K for the enzyme was ≥ 8. Replacement of the mobile phase with a fresh one but in the absence of added salt brought about product elution. Recovery of HRP in this fraction accounts for ≥ 45% of the total activity loaded, with a purification factor of 6. Enzyme activity was also found in the pass‐through fraction and in the remaining liquid (stationary) phase, a fact that should be ascribed to the existence of multiple peroxidase isoforms. SDS‐PAGE of the active fraction showed a protein band at 44 kDa, compatible with the presence of HRP. Thus, the optimised CCC system allowed the separation of HRP directly from a complex biological material. These results open up the possibility of achieving protein separation with CCC/ATPS and of scaling‐up processes in industrial separators.
HPTLC analysis of Withaferine A from an herbal extract and polyherbal formulations
Authors: Mahadevan N. , Rahul P. Kasar , Subburaju T. , Suresh B.
Published: December 2003

Withania somnifera has been used in Ayurvedic medicine for treatment of depression and inflammation, and as an aphrodisiac. It contains many phytochemicals such as Withaferine A, withanine, anahygrine, tropine, and withanolides. Of these, withaferine A is considered to be the most active compound. Withaferine A was estimated in herbal extract and polyherbal formulations by high performance thin layer chromatography (HPTLC). As there is no official HPTLC protocol for quantitation of the above phytochemicals, an attempt was made to quantify withaferine A in herbal extract and polyherbal formulations produced from Withania somnifera. Precoated silica gel G (aluminium backed) plates were used as stationary phase and toluene:ethyl acetate: formic acid (50 : 15 : 5) was used as mobile phase. Detection and quantification were performed by densitometry at λ 213 nm. The linear range was 1 μg to 3 μg. This HPTLC method was found to be reproducible, accurate, and precise.