bluuebunny/crossref_metadata_2025 huggingface dataset:
Fractal Mapping of Pore and Solid Attributes
Authors: Zamora‐Castro S. A. , Oleschko K. , Flores L. , Ventura E. , Parrot J. F.
Published: May 2008

Soil structure depends on its genesis and consists of highly variable pore and solid networks. Several internal and external factors affect the attributes of these networks, with water being the most aggressive agent. In this study, we used selected fractal parameters (called descriptors) to quantify the basic topological attributes—compactness and connectedness—as well as lacunarity and roughness of porous materials, with special attention to sampling error and population variance dynamics. Four microhorizons were sampled from a 1.0‐ by 1.0‐ by 1.6‐m monolith during a long‐term drying period under controlled conditions. A comparative fractal analysis of selected multitemporal (11 mo) and multiscale (50×, 500×, 1000×, and 5000×) scanning electron microscopy (SEM) images was accomplished for the following layers with contrasting texture or structure: loam topsoil, pure basaltic compacted sand, and two amorphous lacustrine clays. The scale invariance (self‐similarity) of pore and solid networks was documented. A complex relationship was found between the descriptor mean values and corresponding variances. Simple power‐law relations were established between the standard deviation (and variance) and layer depth, as well as scale and sampling time. Pearson's r correlation criterion was applied to measure the degree of association between multiobjective fractal descriptors. Systematic and standardized fractal analysis of multiscale images is recommended for the statistical quantitative description of complex and dynamic pore and solid networks.
Modeling Local Scaling Properties for Multiscale Mapping
Authors: Cheng Qiuming
Published: May 2008

Mapping surface soil properties and estimating soil parameters with multiresolution data has been significantly advanced by newly developed multiscale mapping technologies, which incorporate the concept and models of scaling analysis in data processing. This study was conducted to develop a new multiscale mapping technique on the basis of a power‐law model characterizing local singularity of exploratory data for mapping surface soil properties. A field with singularity due to self‐organization or self‐similarity properties of the underlying processes can be modeled by multifractal models. These types of data may not have the statistical stationary property required by ordinary geostatistical mapping techniques. The new mapping technique utilizes a scaling property for data interpolation and for downscaling image processing. The inputs, either point data or an image, can be separated into a nonsingular background component for estimation purposes and an anomalous component of singularity for multiscale high‐pass filtering purposes. When used for the purpose of data interpolation, this new method assigns weights for data interpolation by taking into account not only the distance between neighborhood points but also local structures and singularity of the field. The results of application of the method to a data set of geochemical concentration values of Ag from 1172 lake sediments in the Gowganda area of Ontario, Canada, have delineated favorable target areas with strong singularity of Ag concentrations caused by mineralization in lake sediments.
A Numerical Procedure to Calculate Hydraulic Conductivity for an Arbitrary Pore Size Distribution
Authors: Blank L. Aaron , Hunt A. G. , Skinner T. E.
Published: May 2008

The ability to calculate soil hydraulic properties from soil physical data has been a dominant objective of soil physics research since the 1950s. The purpose of this study was to develop an approach based on modern physics to deal with an arbitrary porous medium. Some important advances resulted from applying critical path analysis from percolation theory and percolation scaling to a truncated random fractal model (Rieu and Sposito) of a soil. In fact, some of the perceived limitations of the fractal model at high and low saturations were reevaluated as strengths in the previous application. Nevertheless, it is not realistic to expect all media to be characterized accurately in such a simple fashion. We developed an appropriate generalization of the description of the medium to an arbitrary pore size distribution while maintaining the complications related to fluid connectivity at high and low saturations relating to percolation theory. It also maintains the relevance of the pore size distribution to the hydraulic conductivity through the application of critical path analysis. A numerical routine was constructed to apply these concepts to an arbitrary pore size distribution, which in our case was inferred from experimentally determined particle size data. Although more than 50 soils were investigated, our preliminary study does not indicate what the general relevance of fractal models is.
Modeling Coupled Surface–Subsurface Flow Processes: A Review
Authors: Furman Alex
Published: May 2008

Surface and subsurface flow systems are inherently unified systems that are often broken into sections for logical (e.g., time scales) and technical (e.g., analytical and computational solvability) reasons. While the basic physical laws are common to surface and subsurface systems, spatial and temporal dimensions as well as the continuum approach used for the subsurface lead to different formulations of the governing partial differential equations. While in most applications such decoupling of the systems works well and allows a very accurate and efficient description of the individual system by treating the adjacent system as a boundary condition, in the case of water flow over a porous medium, it does not. Therefore coupled models are in increasing use in this field, led mostly by watershed and surface irrigation modelers. The governing equations of each component of the coupled system and the coupling physics and mathematics are reviewed first. Three different coupling schemes are identified, namely the uncoupled (with the degenerated uncoupled scheme being a special case of the uncoupled), the iteratively coupled, and the fully coupled. Next, the different applications of the different coupling schemes, sorted by field of application, are reviewed. Finally, some research gaps are discussed, led by the need to include vertical momentum transfer and to expand the use of fully coupled models toward surface irrigation applications.
Modeling Colloid‐Facilitated Contaminant Transport in the Vadose Zone
Authors: Flury Markus , Qiu Hanxue
Published: May 2008

Subsurface colloids can enhance the movement of strongly sorbing contaminants, a phenomenon called colloid‐facilitated contaminant transport. In the presence of mobile subsurface colloids, contaminants may move faster and farther than in the absence of colloids, thereby bypassing the filter and buffer capacity of soils and sediments. Fate and transport models neglecting colloid‐facilitated transport therefore often underpredict contaminant movement. Long‐term predictions of contaminant fate and transport as well as risk assessment rely on an accurate representation of subsurface processes, and in the case of strongly sorbing contaminants, need to consider mobile colloids as potential contaminant carriers. The purpose of this review is to discuss the current knowledge and recent developments of modeling colloid‐facilitated contaminant transport in the vadose zone. The main part of this review is devoted to the discussion of conceptual models used to describe colloid‐facilitated contaminant transport in the vadose zone and their mathematical implementation. Modeling of colloid‐facilitated contaminant transport involves various interactions, including colloid attachment to and detachment from the solid matrix and the air–water interface, contaminant adsorption to and desorption from colloids and transport with mobile colloids, and contaminant adsorption to and desorption from the solid matrix. Most of these processes in colloid‐facilitated contaminant transport models have been described by first‐ or second‐order kinetics. The unique feature of the vadose zone is the presence of an air phase, which affects colloid and contaminant transport in several ways. Colloids can be trapped in immobile water, strained in thin water films and in the smallest regions of the pore space, or attached to the air–water interface itself. The modeling of colloid‐facilitated contaminant transport in the vadose zone has mostly been theoretical, and tested only with column experiments; field applications are still lacking.
Scalable Modeling of Carbon Tetrachloride Migration at the Hanford Site Using the STOMP Simulator
Authors: White M. D. , Oostrom M. , Rockhold M. L. , Rosing M.
Published: May 2008

Numerical simulation has been applied in support of the U.S. Department of Energy's efforts to characterize the nature and distribution of CCl4 contamination in the deep vadose zone at the Hanford site, near Richland, WA. Three‐dimensional simulations were executed using layered and heterogeneous distributions of soil properties to investigate the vertical and lateral distribution of CCl4 beneath its release point (216‐Z‐9 trench) and the effects of soil vapor extraction. The complexity of the modeled physical processes—namely, the nonlinearities associated with multifluid subsurface flow, including phase transitions and hysteresis in the relative permeability–saturation–capillary pressure functions—limits the grid resolution when executed using single‐processor computers. To achieve higher grid resolutions and acceptable detail in the simulation results for subsurface distribution and remediation of CCl4, execution on multiple processors was required. We have developed a scalable implementation of a multifluid subsurface flow and transport simulator, STOMP, with capabilities for volatile organic compounds. Developing scientific software for execution on parallel computers has unique challenges. The guiding objectives for developing this scalable code were to keep the source coding readable and modifiable by subsurface scientists, to allow for both sequential and scalable processing, and to depend on domain scientists for code parallelization and scalable linear system solvers.
Evaluating Interactions between Groundwater and Vadose Zone Using the HYDRUS‐Based Flow Package for MODFLOW
Authors: Twarakavi Navin Kumar C. , Šimůnek Jirka , Seo Sophia
Published: May 2008

In the past, vadose zone processes in groundwater flow models were dramatically simplified (or even neglected) due to constraints on computational resources. The one‐dimensional unsaturated flow package HYDRUS, recently developed for the groundwater model MODFLOW, was evaluated and compared with other contemporary modeling approaches used to characterize vadose zone effects in groundwater models. Being fully incorporated into the MODFLOW program, the HYDRUS package provides MODFLOW with recharge fluxes at the water table, while MODFLOW provides HYDRUS with the position of the groundwater table that is used as the bottom boundary condition in the package. The performance of the HYDRUS package was analyzed for three case studies of increasing complexity: (i) a one‐dimensional infiltration experiment; (ii) a two‐dimensional water table recharge experiment; and (iii) a hypothetical regional‐scale groundwater flow problem. The computational need and modeling efficiency of the HYDRUS package was compared with other relevant MODFLOW packages (VSF, UZF1, and REC‐ET). For smaller scale problems (up to two dimensions), the VSF process and the HYDRUS and UZF1 packages performed comparably well in terms of modeling efficiency and simulation times. Because of the high computational demand, it was not feasible to use the VSF process on a typical personal computer for the hypothetical large‐scale groundwater problem. The HYDRUS package provided a much more efficient alternative to VSF for this large‐scale groundwater problem and could better account for vadose zone processes than the UZF1 and REC‐ET packages. For large‐scale groundwater problems, the HYDRUS package provides an optimal tradeoff between computational effort and accuracy of model simulations for coupled vadose zone–groundwater problems.
Colloid Transport and Retention in Unsaturated Porous Media: A Review of Interface‐, Collector‐, and Pore‐Scale Processes and Models
Authors: Bradford Scott A. , Torkzaban Saeed
Published: May 2008

Our ability to accurately simulate the transport and retention of colloids in the vadose zone is currently limited by our lack of basic understanding of colloid retention processes that occur at the pore scale. This review discusses our current knowledge of physical and chemical mechanisms, factors, and models of colloid transport and retention at the interface, collector, and pore scales. The interface scale is well suited for studying the interaction energy and hydrodynamic forces and torques that act on colloids near interfaces. Solid surface roughness is reported to have a significant influence on both adhesive and applied hydrodynamic forces and torques, whereas non‐Derjaguin–Landau–Verwey–Overbeek (DLVO) forces such as hydrophobic and capillary forces are likely to play a significant role in colloid interactions with the air–water interface. The flow field can be solved and mass transfer processes can be quantified at the collector scale. Here the potential for colloid attachment in the presence of hydrodynamic forces is determined from a balance of applied and adhesive torques. The fraction of the collector surface that contributes to attachment has been demonstrated to depend on both physical and chemical conditions. Processes of colloid mass transfer and retention can also be calculated at the pore scale. Differences in collector‐ and pore‐scale studies occur as a result of the presence of small pore spaces that are associated with multiple interfaces and zones of relative flow stagnation. Here a variety of straining processes may occur in saturated and unsaturated systems, as well as colloid size exclusion. Our current knowledge of straining processes is still incomplete, but recent research indicates a strong coupling of hydrodynamics, solution chemistry, and colloid concentration on these processes, as well as a dependency on the size of the colloid, the solid grain, and the water content.
A new electromagnetic exposure metric: High frequency voltage transients associated with increased cancer incidence in teachers in a california school
Authors: Milham Samuel , Morgan L. Lloyd
Published: May 2008

Background

In 2003 the teachers at La Quinta, California middle school complained that they had more cancers than would be expected. A consultant for the school district denied that there was a problem.

Objectives

To investigate the cancer incidence in the teachers, and its cause.

Method

We conducted a retrospective study of cancer incidence in the teachers' cohort in relationship to the school's electrical environment.

Results

Sixteen school teachers in a cohort of 137 teachers hired in 1988 through 2005 were diagnosed with 18 cancers. The observed to expected (O/E) risk ratio for all cancers was 2.78 (P = 0.000098), while the O/E risk ratio for malignant melanoma was 9.8 (P = 0.0008). Thyroid cancer had a risk ratio of 13.3 (P = 0.0098), and uterine cancer had a risk ratio of 9.2 (P = 0.019). Sixty Hertz magnetic fields showed no association with cancer incidence. A new exposure metric, high frequency voltage transients, did show a positive correlation to cancer incidence. A cohort cancer incidence analysis of the teacher population showed a positive trend (P = 7.1 × 10−10) of increasing cancer risk with increasing cumulative exposure to high frequency voltage transients on the classroom's electrical wiring measured with a Graham/Stetzer (G/S) meter. The attributable risk of cancer associated with this exposure was 64%. A single year of employment at this school increased a teacher's cancer risk by 21%.

Conclusion

The cancer incidence in the teachers at this school is unusually high and is strongly associated with high frequency voltage transients, which may be a universal carcinogen, similar to ionizing radiation. Am. J. Ind. Med. 51:579–586, 2008. © 2008 Wiley‐Liss, Inc.
A further example of a distinctive autosomal recessive syndrome comprising neonatal diabetes mellitus, intestinal atresias and gall bladder agenesis
Authors: Chappell Louise , Gorman Shaun , Campbell Fiona , Ellard Sian , Rice Gillian , Dobbie Angus , Crow Yanick
Published: May 2008

We report a patient born to consanguineous parents as a further example of a recently described phenotype comprising neonatal diabetes, intestinal atresias and gall bladder agenesis. Other reports have described cases with overlapping patterns including malrotation, biliary atresia and pancreatic hypoplasia (e.g. as described by Martínez‐Frías). We propose that these cases may represent variations of the same syndrome. It is likely that this disorder is inherited as an autosomal recessive trait. Our case is the first to have neonatal diabetes without a demonstrable structural pancreatic abnormality, showing that a deficit in pancreatic function is involved. We sequenced genes with a recognized role in monogenic forms of diabetes, including KCNJ11, ABCC8, GCK, IPF1, HNF1β, NeuroD1 and TCF7L2, as well as a novel candidate gene, HNF6, known to be involved in hepatobiliary and pancreatic development, but did not identify mutations. © 2008 Wiley‐Liss, Inc.
Association of syndromic mental retardation with an Xq12q13.1 duplication encompassing the oligophrenin 1 gene
Authors: Bedeschi Maria Francesca , Novelli Antonio , Bernardini Laura , Parazzini Cecilia , Bianchi Vera , Torres Barbara , Natacci Federica , Giuffrida Maria Grazia , Ficarazzi Paola , Dallapiccola Bruno , Lalatta Faustina
Published: May 2008

OPHN1 mutations cause a syndromic form of mental retardation (MR) characterized by cerebellar hypoplasia, early hypotonia, motor and speech delay, with occasional seizures and strabismus. Here we report on a familial chromosome duplication spanning about 800 Kb of Xq12q13.1, associated with MR and a distinctive phenotype in the affected male, but not in his heterozygous mother. The parents were healthy and non‐consanguineous with a history of three pregnancies. The first resulted in the birth of a boy with MR, motor impairment and seizures. The second pregnancy was terminated because of trisomy 18. At the time of the third, the first affected boy was analyzed by array‐CGH, which revealed a 800 Kb duplication at Xq12q13.1, encompassing three genes, including OPHN1. This mutation was inherited from his healthy mother and was not present in any of the three maternal brothers. To our knowledge this is the first report of a clinical phenotype associated with duplication of Xq12q13. © 2008 Wiley‐Liss, Inc.
22q11.2 deletion syndrome in patients admitted to a cardiac pediatric intensive care unit in Brazil
Authors: Rosa Rafael F.M. , Pilla Carlo B. , Pereira Vera L.B. , Flores José A.M. , Golendziner Eliete , Koshiyama Dayane B. , Hertz Michele T. , Ricachinevsky Cláudia P. , Roman Tatiana , Varella‐Garcia Marileila , Paskulin Giorgio A.
Published: May 2008

The 22q11.2 deletion syndrome (22q11DS) is one of the most recognizable causes of congenital heart defects (CHDs), but the frequency varies in non‐selected populations. The purpose of this study was to determine the incidence and clinical features of patients with CHD and 22q11DS admitted to a pediatric cardiology intensive care unit in Brazil. In a prospective study, we evaluated a consecutive series of 207 patients with a CHD following a clinical protocol and cytogenetic analysis by high resolution karyotype and fluorescent in situ hybridization (FISH). 22q11DS was identified in four patients (2%), a frequency similar to studies that evaluated subjects with major CHDs in other countries. Despite this similarity, we believe that the low rate of prenatal identification of CHDs and the limited access of these patients to appropriate diagnosis and care, which occur in our region, could have had an influence on this frequency. It is possible that 22q11DS patients with a severe CHD could have died before having a chance to access a tertiary hospital, leading to an underestimate of its frequency. © 2008 Wiley‐Liss, Inc.
Ermittlung der Tragfähigkeit und insbesondere der Belastbarkeit einer Spannbeton‐Straßenbrücke mittels Dynamischem Bauwerksmonitoring
Authors: Veit‐Egerer Robert , Wenzel Helmut
Published: May 2008

Bei der Straßenbrücke Komořany, Tschechien handelt es sich um eine 2‐spurige Querung einer mehrgleisigen Verbindung, die als Spannbetonbrücke ausgeführt ist. Das Haupttragwerk besteht aus zwei Feldern mit einer Gesamtlänge von rund 63 m. Im Hauptfeld ist dann ein aus neun vorgespannten Betonfertigteilen (I‐Träger) gefertigter Einhängeträger über zwei Gerbergelenke in das Brückentragwerk eingefügt. Diese Fertigteile werden quer zur Brückenachse über Zugstangen zusammengehalten, welche durch deren Ober‐ und Untergurte geführt werden, um eine kraftschlüssige Lastableitung als Gesamtquerschnitt zu gewährleisten. Gegenstand der vorliegenden Untersuchung ist eine dynamische Analyse an der Straßenbrücke Komořany mit BRIMOS®, wodurch der globale Erhaltungszustand des Tragwerks analysiert werden soll, wobei insbesondere die Tragfähigkeit bzw. die Belastbarkeit der Tragstruktur festgelegt und damit Empfehlungen für die weitere Betriebsdauer gegeben werden. Das Hauptaugenmerk liegt dabei auf dem Einhängeträger, der a priori sowohl global (Gerbergelenke) als auch lokal (Quervorspannung) besondere Aufmerksamkeit erfordert.
Modellbildung zur Simulation von Stahlfaserbeton unter hochdynamischer Belastung
Authors: Gebbeken Norbert , Greulich Stefan , Pietzsch Achim , Hartmann Thomas
Published: May 2008

Für den baulichen Schutz vor außergewöhnlichen Beanspruchungen werden Werkstoffe mit problemangepassten Eigenschaften benötigt. Einer dieser Werkstoffe ist Stahlfaserbeton. Für hochdynamische Lasten aus Impakt oder Explosion ist der Werkstoff Stahlfaserbeton jedoch noch nicht hinreichend erforscht.

Dieser Beitrag beschreibt ein neues, auf empirischen Zusammenhängen basierendes Materialmodell zur Simulation von Stahlfaserbeton mit unterschiedlichen Stahlfasergehalten unter hochdynamischer Beanspruchung. Es beinhaltet auch ein Schädigungsmodell, das die Verringerung der Steifigkeit und der Festigkeit des Stahlfaserbetons infolge plastischer Verformungen (Kompaktion und Gestaltänderung) beschreibt.

Das Modell ist in eine Hydrocode‐Umgebung implementiert und wurde anhand einer Vielzahl von Ansprengversuchen validiert. Dabei konnte gezeigt werden, dass numerische Simulationen mit dem neuen Stahlfaserbetonmodell geeignet sind, aufwändige und teure Versuche zu ergänzen bzw. zu reduzieren.
Replicon‐free and markerless methods for genomic insertion of DNAs in phage attachment sites and controlled expression of chromosomal genes in Escherichia coli
Authors: Chiang Chung‐Jen , Chen Po Ting , Chao Yun‐Peng
Published: May 2008

Genetic manipulation of cells for desired traits is the most appreciable strategy implemented in the field of bioengineering. However, this approach closely relies on the use of plasmids and is commonly afflicted by the potential problem of plasmid instability and safety caution. Meanwhile, it may also lead to the spread of antibiotic‐resistant markers with replicons of plasmids to the environment. However, this issue has long been neglected. In this study, we have addressed these subjects by developing replicon‐free and markerless methods for chromosomal insertion of genes and controlled expression of genomic genes in Escherichia coli. For the former application, the integration vectors of conditional replication were incorporated with the prophage attachment site and duplicated FRT sites. Their utility was illustrated by site‐specific insertion of target genes, the endogenous dxs gene and three heterologous genes consisting of gps, crtI, and crtB, fused to T7 promoter into E. coli genome. For the latter application, the template vectors for promoter replacement were constructed to carry a DNA cassette containing the T7 promoter linked to a selective marker flanked with the FRT site. Subsequently, it was illustrated by replacement of the native promoter of chromosomal pckA by the T7 promoter. Finally, with the aid of FLP recombinase supplied from a helper plasmid, the regions containing replicon and/or selective markers in inserted DNAs were eliminated from integrants for both approaches. As a consequence, the expression of these five genes was subject to control by one response regulator, T7 RNA polymerase, in a regulon way, resulting in a high and stable production of lycopene in the cell. This result indicates the promise of developed methods for genome engineering in E. coli. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc.
Modeling of Xanthophyllomyces dendrorhous growth on glucose and overflow metabolism in batch and fed‐batch cultures for astaxanthin production
Authors: Liu Yuan‐Shuai , Wu Jian‐Yong
Published: May 2008

An astaxanthin‐producing yeast Xanthophyllomyces dendrorhous ENM5 was cultivated in a liquid medium containing 50 g/L glucose as the major carbon source in stirred fermentors (1.5‐L working volume) in fully aerobic conditions. Ethanol was produced during the exponential growth phase as a result of overflow metabolism or fermentative catabolism of glucose by yeast cells. After accumulating to a peak of 3.5 g/L, the ethanol was consumed by yeast cells as a carbon source when glucose in the culture was nearly exhausted. High initial glucose concentrations and ethanol accumulation in the culture had inhibitory effects on cell growth. Astaxanthin production was partially associated with cell growth. Based on these culture characteristics, we constructed a modified Monod kinetic model incorporating substrate (glucose) and product (ethanol) inhibition to describe the relationship of cell growth rate with glucose and ethanol concentrations. This kinetic model, coupled with the Luedeking–Piret equation for the astaxanthin production, gave satisfactory prediction of the biomass production, glucose consumption, ethanol formation and consumption, and astaxanthin production in batch cultures over 25–75 g/L glucose concentration ranges. The model was also applied to fed‐batch cultures to predict the optimum feeding scheme (feeding glucose and corn steep liquor) for astaxanthin production, leading to a high volumetric yield (28.6 mg/L) and a high productivity (5.36 mg/L/day). © 2008 Wiley Periodicals, Inc.
Silent mutations result in HlyA hypersecretion by reducing intracellular HlyA protein aggregates
Authors: Gupta Prateek , Lee Kelvin H.
Published: May 2008

Escherichia coli is one of the most widely used hosts for the production of recombinant proteins. Extracellular protein secretion has the advantage of reducing protein aggregation and simplifying downstream purification. The introduction of five rare codons in a specific region of the α‐hemolysin (hlyA) gene previously was shown to result in eightfold improvement in secretion of HlyA via the hemolysin (Type‐I) pathway. Here we investigate the biological basis for the observed phenomenon that translation rate of HlyA protein may be related to the ability to secrete higher levels of HlyA via the Type‐I pathway. A detailed comparative analysis between a hypersecreter mutant strain (hly‐slow) and a control strain (hly‐parent) shows a significant decrease (by ∼50%) in the intracellular level of HlyA protein in the hly‐slow strain relative to the hly‐parent strain. Nearly 100% of the intracellular HlyA protein exists in the inclusion body fraction in both the strains. These results demonstrate the importance of synonymous codon changes in the context of improving HlyA secretion yield via Type‐I pathway and further illustrate that production of high levels of secreted proteins appears to require a balance between translation and secretion rate. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc.
Cell inactivation and membrane damage after long‐term treatments at sub‐zero temperature in the supercooled and frozen states
Authors: Moussa Marwen , Dumont Frédéric , Perrier‐Cornet Jean‐Marie , Gervais Patrick
Published: May 2008

The survival of cells subjected to cooling at sub‐zero temperature is of paramount concern in cryobiology. The susceptibility of cells to cryopreservation processes, especially freeze‐thawing, stimulated considerable interest in better understanding the mechanisms leading to cell injury and inactivation. In this study, we assessed the viability of cells subjected to cold stress, through long‐term supercooling experiments, versus freeze‐thawing stress. The viability of Escherichia coli, Saccharomyces cerevisiae, and leukemia cells were assessed over time. Supercooled conditions were maintained for 71 days at −10°C, and for 4 h at −15°C, and −20°C, without additives or emulsification. Results showed that cells could be inactivated by the only action of sub‐zero temperature, that is, without any water crystallization. The loss of cell viability upon exposure to sub‐zero temperatures is suggested to be caused by exposure to cold shock which induced membrane damage. During holding time in the supercooled state, elevated membrane permeability results in uncontrolled mass transfer to and from the cell maintained at cold conditions and thus leads to a loss of viability. With water crystallization, cells shrink suddenly and thus are exposed to cold osmotic shock, which is suggested to induce abrupt loss of cell viability. During holding time in the frozen state, cells remain suspended in the residual unfrozen fraction of the liquid and are exposed to cold stress that would cause membrane damage and loss of viability over time. However, the severity of such a stress seems to be moderated by the cell type and the increased solute concentration in the unfrozen fraction of the cell suspension. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc.
Evaluation of CO2‐based cold sterilization of a model hydrogel
Authors: Jiménez A. , Zhang J. , Matthews M.A.
Published: May 2008

The purpose of the present work is to evaluate a novel CO2‐based cold sterilization process in terms of both its killing efficiency and its effects on the physical properties of a model hydrogel, poly(acrylic acid‐co‐acrylamide) potassium salt. Suspensions of Staphylococcus aureus and Escherichia coli were prepared for hydration and inoculation of the gel. The hydrogels were treated with supercritical CO2 (40°C, 27.6 MPa). The amount of bacteria was quantified before and after treatment. With pure CO2, complete killing of S. aureus and E. coli was achieved for treatment times as low as 60 min. After treatment with CO2 plus trace amounts of H2O2 at the same experimental conditions, complete bacteria kill was also achieved. For times less than 30 min, incomplete kill was noted. Several physical properties of the gel were evaluated before and after SC‐CO2 treatment. These were largely unaffected by the CO2 process. Drying curves showed no significant change between treated (pure CO2 and CO2 plus 30% H2O2) and untreated samples. The average equilibrium swelling ratios were also very similar. No changes in the dry hydrogel particle structure were evident from SEM micrographs. Biotechnol. Bioeng. 2008;101: 1344–1352. © 2008 Wiley Periodicals, Inc.
Preparation of human immune effector T cells containing iron‐oxide nanoparticles
Authors: Iida Hironori , Takayanagi Kosuke , Nakanishi Takuya , Kume Akiko , Muramatsu Kouji , Kiyohara Yoshio , Akiyama Yasuto , Osaka Tetsuya
Published: May 2008

Preparation of human immune T cells containing iron‐oxide nanoparticles was carried out for the development of magnetically mediated immunotherapy. Peripheral blood lymphocytes (PBLs) after the incubation with magnetite nanoparticles were found to contain measurable ferric ions, which suggested the incorporation of magnetite nanoparticles. Transmission electron microscopic (TEM) study indicated that the incorporation of magnetite nanoparticles was mediated by endocytosis of PBLs. Furthermore, the effects of dosages and diameter of magnetite nanoparticles on the magnetite incorporation were investigated, and it was demonstrated that the increase in dosage promoted the incorporation of nanoparticles and the uptake into PBLs was more effective for magnetite nanoparticles, which formed smaller aggregations in medium. Finally, the demonstration of magnetite incorporation into enriched T cells and tumor antigen‐specific cytotoxic T lymphocyte (CTL) line promises the achievement of magnetically mediated immunotherapy with tumor‐specific CTLs containing magnetic nanoparticles. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc.
A population analysis of VEGF transgene expression and secretion
Authors: Karoubi Golnaz , Stewart Duncan J. , Courtman David W.
Published: May 2008

The induction of therapeutic angiogenesis with gene therapy approaches has received considerable interest and some limited clinical success. A major drawback to this approach is a lack of understanding of the pharmacokinetics of therapeutic protein delivery. This has become increasingly more relevant as recent studies have illustrated a defined therapeutic window for angiogenic protein secretion into the local microenvironment. For cell based gene therapies, with cells widely distributed throughout the tissue, this implies that any individual cell must attain a specific secretion rate to produce a local angiogenic response. Here we report a reproducible technique enabling the study of growth factor secretion from individual cells following transient plasmid transfection. We demonstrate significant variability in single cell vascular endothelial growth factor (VEGF) secretion with the majority of total protein secretion arising from a small subpopulation of transfected cells. We demonstrate that VEGF secretion is linearly correlated to intracellular plasmid copy number and protein secretion does not appear to reach saturation within the cell population. The selection of gene therapy approaches that optimize individual cell secretion profiles may be essential for the development of effective gene therapies. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc.
Catabolic pathways and cellular responses of Pseudomonas putida P8 during growth on benzoate with a proteomics approach
Authors: Cao Bin , Loh Kai‐Chee
Published: May 2008

The catabolic pathways and cellular responses of Pseudomonas putida P8 during growth on benzoate were studied through proteomics approach. Two‐dimensional gel electrophoresis (2‐DE) gel profiles of P. putida cells grown on 100 and 800 mg/L benzoate were quantitatively compared using threshold criteria and statistical tools. Protein spots of interest were identified through database searching based on peptide mass fingerprints (PMFs) obtained using matrix assisted laser desorption/ionization‐time of flight mass spectrometry (MALDI‐TOF MS). Eight catabolic enzymes involved in both the ortho‐cleavage (CatB, PcaI, and PcaF) and the meta‐cleavage (DmpC, DmpD, DmpE, DmpF, and DmpG) pathways for benzoate biodegradation were identified in P. putida grown on 800 mg/L of benzoate while no meta‐cleavage pathway enzymes were observed in the 2‐DE gel profiles of P. putida grown on 100 mg/L of benzoate. The activation of both the ortho‐ and the meta‐cleavage pathways in P. putida P8 grown on high benzoate concentration was confirmed directly at the protein level. In addition, another 28 differentially expressed proteins were also identified, including proteins involved in (i) detoxification and stress response (AhpC, ATPase‐like ATP‐binding region, putative DNA‐binding stress protein, SodB and catalase/peroxidase HPI); (ii) carbohydrate, amino acid/protein and energy metabolism (isocitrate dehydrogenase, SucC, SucD, AcnB, GabD, ArcA, ArgI, Efp and periplasmic binding proteins of several ABC‐transporters); and (iii) cell envelope and cell division (bacterial surface antigen family protein and MinD). Based on the data obtained, physiological changes of P. putida in response to growth on benzoate at different concentrations were discussed. Biotechnol. Bioeng. 2008;101: 1297–1312. © 2008 Wiley Periodicals, Inc.
Market mavenism and consumer self‐confidence
Authors: Clark Ronald A. , Goldsmith Ronald E. , Goldsmith Elizabeth B.
Published: May 2008

The purpose of this study was to test hypothesized associations between market mavenism and consumer self‐confidence (CSC). A survey of 190 US consumers provided the data. The results showed significant relationships between mavenism and several dimensions of CSC, and regression analysis emphasized the relationships with two of these: information acquisition (confidence in the ability to obtain and use marketplace information) and social outcomes decision making (confidence in obtaining positive reactions from others). These findings both enrich our knowledge of the psychology of market mavenism by suggesting some motivations for these behaviors and suggest marketing strategies can be fine‐tuned to appeal more effectively to this important segment of consumers.

Copyright © 2008 John Wiley & Sons, Ltd.
Effect of concanavalin A (Con‐A) on the hormone production of the unicellular Tetrahymena and the immune cells of the rat. A comparative study
Authors: Csaba György , Pállinger Éva
Published: May 2008

Tetrahymena populations were treated with 10−15 g ml−1 or 10−6 g ml−1 concanavalin‐A (Con‐A) in tryptone‐yeast medium for 1 h. Rat peritoneal immune cells (mast cells, lymphocytes, monocyte‐granulocyte group) were also treated with 10−6 g ml−1 Con‐A, for 1 h. The cells' hormone (ACTH, histamine, serotonin, endorphin, triiodothyronine (T3)) content was measured by using immunocytochemistry and flow cytometry. The extremely low dose of Con‐A universally and significantly elevated the hormone contents, while the result of higher dose was uncertain. In the immune cells, Con‐A significantly decreased the ACTH level in each cell type and histamine level in mast cells. The results demonstrate the very high sensitivity of Tetrahymena receptors for a non‐hormone (lectin) molecule, which can bind to the insulin receptors and mimics the effect of insulin. The results also show that Tetrahymena receptors are more sensitive to lower concentrations of molecules than to higher ones. The universal hormone‐production stimulating effect of Con‐A—which is observed in Tetrahymena—is specified in rat. Copyright © 2008 John Wiley & Sons, Ltd.
Mitochondria as the target for mildronate's protective effects in azidothymidine (AZT)‐induced toxicity of isolated rat liver mitochondria
Authors: Pupure Jolanta , Fernandes Maria A. S. , Santos Maria S. , Moreno António J. M. , Kalvinsh Ivars , Klusa Vija , Oliveira Catarina R.
Published: May 2008

Previously mildronate, an aza‐butyrobetaine derivative, was shown to be a cytoprotective drug, through its mechanism of action of inhibition of carnitine palmitoyltransferase‐1, thus protecting mitochondria from long‐chain fatty acid accumulation and subsequent damage. Recently in an azidothymidine (AZT)‐induced cardiotoxicity model in vivo (in mice), we have found mildronate's ability of protecting heart tissue from nuclear factor κB abnormal expression. Preliminary data also demonstrate cerebro‐ and hepatoprotecting properties of mildronate in AZT‐toxicity models. We suggest that mildronate may target its action predominantly to mitochondria. The present study in isolated rat liver mitochondria was designed to clarify mitochondrial targets for mildronate by using AZT as a model compound. The aim of this study was to investigate: (1) whether mildronate may protect mitochondria from AZT‐induced toxicity; and (2) which is the most critical target in mitochondrial processes that is responsible for mildronate's regulatory action. The results showed that mildronate protected mitochondria from AZT‐induced damage predominantly at the level of complex I, mainly by reducing hydrogen peroxide generation. Significant protection of AZT‐caused inhibition of uncoupled respiration, ADP to oxygen ratio, and transmembrane potential were also observed. Mildronate per se had no effect on the bioenergetics, oxidative stress, or permeability transition of rat liver mitochondria. Since mitochondrial complex I is the first enzyme of the respiratory electron transport chain and its damage is considered to be responsible for different mitochondrial diseases, we may account for mildronate's effectiveness in the prevention of pathologies associated with mitochondrial dysfunctions. Copyright © 2008 John Wiley & Sons, Ltd.
In vitro effects of 2‐methoxyestradiol on MCF‐12A and MCF‐7 cell growth, morphology and mitotic spindle formation
Authors: Van Zijl Catherina , Lottering Mona‐Liza , Steffens Francois , Joubert Annie
Published: May 2008

The influence of 2‐methoxyestradiol (2ME) was investigated on cell growth, morphology and spindle formation in a tumorigenic (MCF‐7) and non‐tumorigenic (MCF‐12A) epithelial breast cell line. Inhibition of cell growth was more pronounced in the MCF‐7 cells compared to the MCF‐12A cells following 2ME treatment. Dose‐dependent studies (10−5 – 10−9 M) revealed that 10−6 M 2ME inhibited cell growth by 44% in MCF‐12A cells and by 84% in MCF‐7 cells (p‐value < 0.05). 2ME‐treated MCF‐7 cells showed abnormal metaphase cells, membrane blebbing, apoptotic cells and disrupted spindle formation. These observations were either absent or less prominent in MCF‐12A cells. 2ME had no effect on the length of the cell cycle between S‐phase and the time a mitotic peak was reached in either cell line but MCF‐7 cells were blocked in mitosis with no statistically significant alterations in the phosphorylation status of Cdc25C. Nevertheless, Cdc2 activity was significantly increased in MCF‐7 cells compared to MCF‐12A cells (p‐value < 0.05). The results indicate that 2ME disrupts mitotic spindle formation and enhances Cdc2 kinase activity, leading to persistence of the spindle checkpoint and thus prolonged metaphase arrest that may result in the induction of apoptosis. The tumorigenic MCF‐7 cells were especially sensitive to 2ME treatment compared to the normal MCF‐12A cells. Therefore, differential mechanism(s) of growth inhibition are evident between the normal and tumorigenic cells. Copyright © 2008 John Wiley & Sons, Ltd.
Membranadsorbersysteme in der Proteinaufreinigung: Screening‐Möglichkeiten
Authors: Kökpinar Ö. , Walter J.‐G. , Anton F. , Mönster A. , Kasper C. , Stahl F. , Scheper T.
Published: May 2008

Unterschiedlich funktionalisierte Membranen (Membranen für Ionenaustausch‐, Affinitäts‐ und Metallchelatchromatographie) wurden auf ihr Bindungs‐ bzw. Elutionsverhalten und auf ihre Eignung zur Isolierung und Reinigung von Modellproteinen aus einem Gemisch sowie aus Kulturüberständen und Zelllysaten untersucht. Hierzu werden zwei verschiedene Membranadsorbereinheiten als Screening‐Module verwendet, die das Arbeiten im Mikrolitermaßstab vereinfachen: spin columns und 8‐strips.
Industrielle Biotechnologie: Wirtschaftspolitische Bedeutung, Wettbewerbsfähigkeit und Standortattraktivität Deutschlands
Authors: Nusser M.
Published: May 2008

Deutschland ist in der industriellen Biotechnologie im internationalen Wettbewerb sehr gut positioniert. Zwar gibt es Schwächen und Risiken (z. B. unzureichende Politikkoordination und Verfügbarkeit von Risikokapital, zu wenige Demonstrationsanlagen, zukünftige Engpässe beim qualifizierten Personal), jedoch ergeben sich auf Grund der Stärken (u. a. starke technologische Wissensbasis, gut ausgebildete Arbeitskräfte, wettbewerbsfähige industrielle Basis in wichtigen Anwenderbranchen mit Zugang zu großen Exportmärkten) zukünftig enorme Innovations‐, Wachstums‐ und Beschäftigungspotenziale.
Aufarbeitung von Plasmid‐DNA für Gentherapie und genetische Impfung
Authors: Voß C.
Published: May 2008

Plasmid‐DNA wird als Klonierungsvektor zum Einbringen rekombinanter Gene in Mikroorganismen genutzt. Seit den 1990er Jahren wird dieses Prinzip auch zur Übertragung therapeutischer Gene in der Gentherapie und der genetischen Impfung verwendet. Diese Form der nicht viralen Gentherapie stellt eine deutlich risikoärmere Variante im Vergleich zur viralen Gentherapie dar. Zur Deckung des Bedarfs an Plasmid‐DNA in klinischen Studien und für in Zukunft zugelassene Therapeutika sind Produktionsverfahren erforderlich, die eine Herstellung im Multigramm‐ bis Kilogramm‐Maßstab möglich machen. Besondere Hersausforderungen werden hier im Bereich des Zellaufschlusses, der Abtrennung strukturell verwandter Verbindungen und der Prozess‐ und Produktanalytik gestellt. Dieser Übersichtsbeitrag fasst die Entwicklungen der letzten Jahre zusammen.
Verfahrens‐ und Katalysatordesign als Aufarbeitungsstrategie für die enzymatische Darstellung von Isomaltose
Authors: Jördening H.‐J. , Erhardt F. A. , Holtkamp M. , Buchholz K. , Scholl S.
Published: May 2008

Es wird die Optimierung der Isomaltoseproduktion durch ein System aus enzymkatalysierter Reaktion und Adsorption des Produkts untersucht. Dafür wurden die Reaktionsbedingungen, die Biokatalysatoreigenschaften sowie die reaktionsintegrierte Abtrennung des Produkts eingehend geprüft. Ausgehend von immobilisierter Dextransucrase als Biokatalysator konnte durch Entwicklung von Coimmobilisaten ein deutlicher Fortschritt erzielt werden. Das beste Ergebnis ließ sich mit einer genetisch modifizierten Dextransucrase (GTFR) erhalten, wodurch die integrierte Abtrennung des Produkts bedeutend erleichtert wird. Der Gesamtprozess aus Biokatalyse und Adsorption für die verschiedenen Modifikationen wurde durch Berechnung der Prozesseffizienzen evaluiert.
Neue Entwicklungen auf dem Gebiet der simulierten Gegenstromchromatographie
Authors: Seidel‐Morgenstern A. , Keßler L. C. , Kaspereit M.
Published: May 2008

Chromatographische Trennverfahren besitzen eine außerordentliche Bedeutung bei der Aufreinigung wertvoller Stoffe im Bereich der pharmazeutischen Industrie, der Biotechnologie und bei der Gewinnung von Feinchemikalien. Typischerweise basieren die Prozesse nach wie vor auf dem Einsatz einer chargenweisen periodischen Injektion der Rohgemische und einer entsprechenden periodischen Sammlung der Produktfraktionen. In den 1960er Jahren wurde als leistungsstarke Alternative die auf einer Reihenschaltung von mehreren Trennsäulen basierende und einen Gegenstrom zwischen stationärer und mobiler Phase ausnutzende kontinuierliche Chromatographie entwickelt, die zunächst mit großem Erfolg in der Petrochemie und in der Zuckerindustrie zum Einsatz kam. In den letzten Jahren hat die so genannte Simulated Moving Bed (SMB)‐Chromatographie zunehmend Eingang in die pharmazeutische Industrie gefunden. Insbesondere Enantiomerentrennungen unter Verwendung chiraler stationärer Phasen sind zurzeit eine starke Triebfeder für die Entwicklung neuer und noch leistungsfähigerer Prozessvarianten. Gegenwärtig wächst auch auf Grund des steigenden Interesses an effizienten Methoden zur Aufarbeitung von Biomolekülen der Bedarf an leistungsstarken chromatographischen Verfahren. In diesem Aufsatz wird ein Überblick über neue Vorschläge und Trends auf dem Gebiet der kontinuierlichen Gegenstromchromatographie gegeben.