bluuebunny/crossref_metadata_2025 huggingface dataset:
A binary‐based on‐chip CNN solution for pixel‐level snakes
Authors: Brea V. M. , Laiho M. , Vilariño D. L. , Paasio A. , Cabello D.
Published: June 2006

This paper introduces a binary‐based on‐chip cellular neural network (CNN) solution for pixel‐level snakes. Every cell in the array comprises circuitry for B/W and grey‐scale processing. The B/W processing is performed with a positive range high‐gain discrete‐time (DT)CNN model with 1‐bit of programmability. The grey‐scale processing is executed on a dedicated sub‐cell. The design efforts are mainly focused on area consumption and processing speed. The result is a chip with a resolution of 9 × 9 cells in a 0.18 µm CMOS technology process and a density of more than 700cells/mm2. Simulations at schematic level lead to a time of less than 100ns for every DTCNN step. The peak power dissipation is kept at a few watts in a hypothetical chip of 128 × 128 cells. Copyright © 2006 John Wiley & Sons, Ltd.
Digital implementation of cellular sensor‐computers
Authors: Földesy Péter , Zarándy Ákos , Rekeczky Csaba , Roska Tamás
Published: June 2006

A bit‐sliced digital implementation method of the cellular sensor‐computer is proposed. The proposed sensor‐computer architecture is analysed, and an implementation example is introduced. The analogue and the digital implementation methods are compared. It is found that on or below 0.18 µm technology the digital implementation of the cellular sensor‐computer is a viable alternative to the analogue versions in general‐purpose designs. Copyright © 2006 John Wiley & Sons, Ltd.
Cellular non‐linear networks for microcirculation applications
Authors: Sapuppo F. , Bucolo M. , Intaglietta M. , Fortuna L. , Arena P.
Published: June 2006

Cellular nonlinear network methodology and related technology was used for the implementation of a real‐time image processing system for the study of structural and functional parameters in the microcirculation. The observation of these parameters is basic in the description and characterization of the physiological phenomena occurring in the peripheral vascular network at a micrometric scale. They contribute to the understanding of the global cardiovascular regulatory system for both experimental and clinical applications. The aim of this new CNN‐based approach is to implement a real‐time system that is based on automated image processing algorithms that overcome the limits of the conventional invasive, manual, and operator dependant methods. It would also allow an objective protocol in thein vivoexperiments. These conditions are necessary in biological studies in order to make the experimental results reproducible and comparable. An algorithm was implemented, by exploiting the CNN structure potentiality, in order to characterize the morphology of the capillary maps, to determine the red blood cells density in blood (Hematocrit), and to calculate red blood cells velocity (RBCV) in capillaries from image sequences captured duringin vivoexperiments by intravital microscopy. The algorithm was designed and tested using a CNN simulator and then optimized and implemented via hardware on the ACE16k CNN chip. The final results of the image processing were furthermore compared with measurements obtained with conventional, manual methods used in microvascular studies. Copyright © 2006 John Wiley & Sons, Ltd.
Formation of three‐dimensional fetal myocardial tissue cultures from rat for long‐term cultivation
Authors: Just Lothar , Kürsten Anne , Borth‐Bruhns Thomas , Lindenmaier Werner , Rohde Manfred , Dittmar Kurt , Bader Augustinus
Published: June 2006

Three‐dimensional cardiomyocyte cultures offer new possibilities for the analysis of cardiac cell differentiation, spatial cellular arrangement, and time‐specific gene expression in a tissue‐like environment. We present a new method for generating homogenous and robust cardiomyocyte tissue cultures with good long‐term viability. Ventricular heart cells prepared from fetal rats at embryonic day 13 were cultured in a scaffold‐free two‐step process. To optimize the cell culture model, several digestion protocols and culture conditions were tested. After digestion of fetal cardiac ventricles, the resultant cell suspension of isolated cardiocytes was shaken to initialize cell aggregate formation. In the second step, these three‐dimensional cell aggregates were transferred onto a microporous membrane to allow further microstructure formation. Autonomously beating cultures possessed more than 25 cell layers and a homogenous distribution of cardiomyocytes without central necrosis after 8 weeks in vitro. The cardiomyocytes showed contractile elements, desmosomes, and gap junctions analyzed by immunohistochemistry and electron microscopy. The beat frequency could be modulated by adrenergic agonist and antagonist. Adenoviral green fluorescent protein transfer into cardiomyocytes was possible and highly effective. This three‐dimensional tissue model proved to be useful for studying cell–cell interactions and cell differentiation processes in a three‐dimensional cell arrangement. Developmental Dynamics 235:2200–2209, 2006. © 2006 Wiley‐Liss, Inc.
Isolation of essential oil and supercritical carbon dioxide extract of Juniperus communis L. fruits from Montenegro
Authors: Damjanović Biljana , Skala Dejan , Baras Josip , Petrović‐Djakov Dušanka
Published: June 2006

Ripe fruits (berries) of common juniper (Juniperus communis L.) from northern Montenegro were extracted by hydrodistillation and by supercritical carbon dioxide (SC‐CO2) in a single‐stage separation system. The composition of the extracts was evaluated by GC‐FID and GC‐MS. A total of 38 different compounds were identified and significant differences (qualitative and quantitative) were observed between the hydrodistilled oil and the SC‐CO2 extracts. In the hydrodistilled oil, major compounds were: α‐pinene (28.6–38.2%), sabinene (15.7–20.5%) and myrcene (7.2–18.2%). In the SC‐CO2 extracts, major compounds were: α‐pinene (7.7–30.3%), myrcene (4.5–20.5%) and germacrene B and D (∼6%). The analysis of the results has shown that the grinding process has a significant influence on the yield and chemical composition of essential oil. In SC‐CO2 extraction different pressures were applied and the best process performance regarding chemical composition of the extract and its organoleptic quality was obtained at 90 bar and 40 C in the extraction vessel. Copyright © 2006 John Wiley & Sons, Ltd.
The reaction mechanism of iron and manganese superoxide dismutases studied by theoretical calculations
Authors: Rulíšek Lubomír , Jensen Kasper P. , Lundgren Kristoffer , Ryde Ulf
Published: June 2006

We have studied the detailed reaction mechanism of iron and manganese superoxide dismutase with density functional calculations on realistic active‐site models, with large basis sets and including solvation, zero‐point, and thermal effects. The results indicate that the conversion of O to O2 follows an associative mechanism, with O directly binding to the metal, followed by the protonation of the metal‐bound hydroxide ion, and the dissociation of 3O2. All these reaction steps are exergonic. Likewise, we suggest that the conversion of O to H2O2 follows an at least a partly second‐sphere pathway. There are small differences in the preferred oxidation and spin states, as well as in the geometries, of Fe and Mn, but these differences have little influence on the energetics, and therefore on the reaction mechanism of the two types of superoxide dismutases. For example, the two metals have very similar reduction potentials in the active‐site models, although they differ by 0.7 V in water solution. The reaction mechanisms and spin states seem to have been designed to avoid spin conversions or to facilitate them by employing nearly degenerate spin states. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 1398–1414, 2006
Optimisation of anaerobic/anoxic/oxic process to improve performance and reduce operating costs
Authors: Peng Yongzhen , Wang Xiaolian , Wu Weimin , Li Jun , Fan Jie
Published: June 2006

A laboratory‐scale anaerobic/anoxic/oxic reactor system was used to treat synthetic brewery wastewater for 1 year. The objectives were to enhance denitrifying phosphorus removal, improve biological nutrient removal and reduce operating costs. Three operational strategies were tested: (1) controlling nitrate recirculation to stimulate the growth of denitrifying phosphate‐accumulating organisms; (2) adjusting the volume ratio of the anaerobic/anoxic/oxic zones to enhance anoxic P uptake; (3) bypassing a part of the influent flow into the anoxic zone to maximise anoxic P uptake and denitrification. The results showed that not only was anoxic P uptake enhanced but also energy consumption for aeration could be reduced when the anoxic effluent NO3−‐N concentration was controlled between 1 and 3 mg L−1. The optimal volume ratio of the anaerobic/anoxic/aerobic zones in this system was found to be 1:1:2. The optimal bypass flow ratio was 0.32. The results indicated that the optimal strategies could improve treatment performance and reduce operational costs, but there was still a challenge to treat wastewater with low C/N ratio. Copyright © 2006 Society of Chemical Industry
Apomorphine protects against 6‐hydroxydopamine‐induced neuronal cell death through activation of the Nrf2‐ARE pathway
Authors: Hara Hirokazu , Ohta Mitsuhiro , Adachi Tetsuo
Published: June 2006

NF‐E2‐related factor‐2 (Nrf2), a basic leucine zipper transcription factor, is involved in the expression of numerous detoxifying and antioxidant genes via the antioxidant response element (ARE). Apomorphine (Apo), a dopamine D1/D2 receptor agonist, is used for clinical therapy of Parkinson's disease. On the other hand, Apo is a potent radical scavenger and has protective effects on oxidative stress‐induced cell death. Previously, we have reported that pretreatment of human neuroblastoma SH‐SY5Y cells with Apo enhances protection against 6‐hydroxydopamine (6‐OHDA)‐induced cell death. In this study, we investigated whether the Nrf2‐ARE system is involved in the protection by Apo. Pretreatment of SH‐SY5Y cells with Apo suppressed 6‐OHDA‐induced cell death in a dose‐dependent manner. However, neither SCH23390, a dopamine D1 receptor antagonist, nor sulpiride, a dopamine D2 receptor antagonist, prevented the protective effect of Apo. Apo stimulated the translocation of Nrf2 into the nucleus and the transactivation of the ARE. The expression of heme oxygenase‐1 (HO‐1) was dose dependently induced by Apo. Moreover, we found that the activation of the ARE and the induction of HO‐1 mRNA caused by Apo were suppressed in the presence of the antioxidant N‐acetylcysteine and also that Apo produced intracellular reactive oxygen species (ROS), indicating that the low level of ROS produced by Apo may play a critical role in this phenomenon. Taken together, our findings suggest that not only the function as a radical scavenger but also the function as an Nrf2‐ARE pathway activator may be involved in the neuroprotective effects of Apo. © 2006 Wiley‐Liss, Inc.
Enhanced activation of Ca2+/Calmodulin‐dependent protein kinase II upon downregulation of cyclin‐dependent kinase 5‐p35
Authors: Hosokawa Tomohisa , Saito Taro , Asada Akiko , Ohshima Toshio , Itakura Makoto , Takahashi Masami , Fukunaga Kohji , Hisanaga Shin‐ichi
Published: June 2006

Cyclin‐dependent kinase 5 (Cdk5)‐p35 is downregulated in cultured neurons by N‐methyl‐d‐aspartate (NMDA) via the proteasomal degradation of p35. However, it is not known where in neurons this downregulation occurs or the physiologic meaning of the reaction. We show the enrichment of Cdk5 and p35 in the postsynaptic density and the NMDA‐induced degradation of postsynaptic p35 using brain slices and cultured neurons. To evaluate the role of this downregulation, we examined the relationship between Ca2+/calmodulin‐dependent protein kinase II (CaMKII) activation and Cdk5 downregulation, as events downstream from NMDA stimulation. Glutamate or NMDA stimulation induced CaMKII autophosphorylation over a time course that mirrored the time course of p35 degradation. To simulate the downregulation of postsynaptic Cdk5 in invitro experiments, we used the Cdk5 inhibitor roscovitine. The inhibition of Cdk5 activity by roscovitine enhanced CaMKII autophosphorylation and activation in cultured neurons, and in an isolated postsynaptic‐density‐enriched fraction. These results suggest that Cdk5 activity suppresses CaMKII activation, and that the downregulation of Cdk5 activity after treatment withNMDA facilitates CaMKII activation, leading to the easier induction of long‐term potentiation. © 2006 Wiley‐Liss, Inc.
Differentiation of a human neuroblastoma into neuron‐like cells increases their susceptibility to transduction by herpesviral vectors
Authors: Gimenez‐Cassina Alfredo , Lim Filip , Diaz‐Nido Javier
Published: June 2006

Gene transfer is a powerful tool for functional gene analysis in human cells. In this respect, there is a need to develop experimental models that involve homogeneous cultures of human neuron‐like cells susceptible to gene transduction and that are easy to handle. Here we describe an optimized and reproducible procedure to differentiate human SH‐SY5Y neuroblastoma cells into a homogeneous population of neuron‐like cells. The fully differentiated cells are postmitotic and resemble primary cultured neurons in terms of their cytoskeletal polarity. Notably, differentiated SH‐SY5Y cells are far more susceptible to transduction by herpes simplex virus (HSV‐1)‐based vectors than proliferating SH‐SY5Y cells. This increase in transduction efficiency after neuronal differentiation may be due to the up‐regulation of cell surface receptors for herpesvirus entry. In summary, we propose that fully differentiated human neuron‐like cells obtained from the SH‐SY5Y neuroblastoma may constitute an excellent and versatile experimental tool for gene transfer and functional genomic studies with HSV‐1 vectors. © 2006 Wiley‐Liss, Inc.
Neurovascular and neuronal protection by E64d after focal cerebral ischemia in rats
Authors: Tsubokawa Tamiji , Yamaguchi‐Okada Mitsuo , Calvert John W. , Solaroglu Ihsan , Shimamura Norihito , Yata Kenichiro , Zhang John H.
Published: June 2006

Calpains and cathepsins are two families of proteases that play an important role in ischemic cell death. In this study, we investigated the effect of E64d, a μ‐calpain and cathepsin B inhibitor, in the prevention of neuronal and endothelial apoptotic cell death after focal cerebral ischemia in rats. Rats underwent 2 hr of transient focal ischemia from middle cerebral artery occlusion (MCAO) and were sacrificed 24 hr later. E64d (5 mg/ kg intraperitoneally) was administered 30 min before MCAO. Assessment included neurological function, infarction volume, brain water content, blood–brain barrier permeability, histology, and immunohistochemistry. The E64d‐treated rats had significant brain protection against ischemic damage. We observed a reduction of infarction volume, brain edema, and improved neurological scores in E64d‐treated rats compared with the nontreated control. Furthermore, there was a remarkable reduction in both proteases and caspase‐3 activation and apoptotic changes in both neurons and endothelial cells in E64d‐treated rats. These results suggest that E64d protects the brain against ischemic/reperfusion injury by attenuating neuronal and endothelial apoptosis. © 2006 Wiley‐Liss, Inc.
Effect of valine on the efficiency and precision at S4 cleavage of the Notch‐1 transmembrane domain
Authors: Tanii Hisashi , Jiang Jingwei , Fukumori Akio , Tagami Shinji , Okazaki Yuji , Okochi Masayasu , Takeda Masatoshi
Published: June 2006

Presenilin‐dependent intramembranous proteolysis mediates the dual cleavage of the Notch‐1 protein (S4 and S3) as well as the β amyloid precursor protein (βAPP) (γ40 and ϵ‐site). βAPP has a valine residue just before the γ40 (amyloid β [Aβ] numbering) site and after the ϵ‐site. Both γ40 and ϵ have multiple cleavage sites, and the varieties of γ40 cleavage are associated with Alzheimer's disease (AD). These lines of evidence suggest that valine plays a role in the intramembranous proteolysis. S4 cleavage in the middle of the Notch‐1 transmembrane domain (TMD) corresponds to the γ40 cleavage of βAPP. The cleavage site is in the center of four sequential alanine residues between Ala1731 and Ala1732, neither of which has a valine residue. To investigate the effects of valine on presenilin‐dependent intramembranous proteolysis, we replaced the transmembrane domain residue of Notch‐1 with valine and analyzed the efficiency and precision at S4 and S3. We observed that all valine‐mutated Notch‐1 proteins have a dominant cleavage site (S4) between Ala1731 and Ala1732 with some variations of cleavage precision, suggesting that valine is not indispensable for determining the cleavage site of the Notch‐1 transmembrane domain, but affects the efficiency and precision at S4 cleavage of the Notch‐1 transmembrane domain. © 2006 Wiley‐Liss, Inc.
Spatial and temporal daily rainfall regime in Catalonia (NE Spain) derived from four precipitation indices, years 1950–2000
Authors: Martínez M. D. , Lana X. , Burgueño A. , Serra C.
Published: June 2006

Annual rainfall amount, P, number of rainy days per year, N, average daily intensity in a year, I, and relevance, R, of the contribution of a rainfall class interval to the annual amount are used as pluviometric indices to deeply analyse the description of the complex behaviour of the daily rainfall regime of Catalonia (NE Spain). For this analysis, daily amounts of rainfall from 75 rain gauges for the period 1950–2000 have been considered. Indices N and I are analysed by distinguishing five percentiles (25th, 50th, 75th, 90th and 95th) of the daily rainfall amounts. Index R is evaluated taking into account <25%, 25–50%, 50–75%, 75–90%, ≥90% and ≥95% class intervals. All these indices are described by their mean annual values, standard deviations and consecutive temporal irregularities. Besides the complex orography of the country, effects of the influence of the Mediterranean regime and remoteness of the Iberian Peninsula to the Atlantic coast are detected in the diversity of spatial patterns of the indices. The influence of the Atlantic regime is also found at some places in the Pyrenees, especially those that faced north. All these features are described through a Principal Component Analysis (PCA), which is applied to average annual values of the pluviometric indices, and the subsequent clustering process. Additionally, time trends of the annual indices are analysed for a selected set of 39 rain gauges with an optimum recording continuity. Trends are derived from linear regression, and local statistical significances at the 95% confidence level are established using the Mann–Kendall test. Field significant trends are investigated by means of Monte Carlo simulations. It is worthy of mention that field significant trends have been detected in the number of rainy days for percentiles up to the 75th, all local trends being negative. Field significant trends are also detected in daily intensity, whatever the threshold level, with positive and negative local trends. The relevance index R depicts field significant trends for the first three class intervals, with a predominance of positive local trends in the first two, thus indicating an increasing contribution of light and moderate daily episodes to the annual amounts. Copyright © 2006 Royal Meteorological Society
Volume‐Resolved Nanostructure Survey of a Polymer Part by Means of SAXS Microtomography
Authors: Stribeck Norbert , Camarillo Armando Almendarez , Nöchel Ulrich , Schroer Christian , Kuhlmann Marion , Roth Stephan V. , Gehrke Rainer , Bayer Rüdiger K.
Published: June 2006

Summary: Small‐angle X‐ray scattering (SAXS) microto‐ mography (micro‐CT) resolves structure variation in an anisotropic polyethylene (PE) gradient material with fiber symmetry. 4 900 reconstructed SAXS patterns describe the nanostructure as a function of volume element position in the scanned fiber cross‐section. Reconstruction errors were observed. Their first‐order effect was eliminated by transformation of the SAXS into a multidimensional chord distribution function (CDF). Its analysis shows oriented lamellae stacks in a shell layer and extended chains in the central core of the fiber. We document zones of uni‐ and bimodal structure, variation of long periods, stack heights, and lateral domain extension.

Original SAXS patterns (pseudocolor and 3D plot) from different voxels obtained by micro‐CT reconstruction from measured SAXS projection patterns of a PE rod.

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Original SAXS patterns (pseudocolor and 3D plot) from different voxels obtained by micro‐CT reconstruction from measured SAXS projection patterns of a PE rod.
Apparent diffusion coefficients from high angular resolution diffusion imaging: Estimation and applications
Authors: Descoteaux Maxime , Angelino Elaine , Fitzgibbons Shaun , Deriche Rachid
Published: June 2006

High angular resolution diffusion imaging has recently been of great interest in characterizing non‐Gaussian diffusion processes. One important goal is to obtain more accurate fits of the apparent diffusion processes in these non‐Gaussian regions, thus overcoming the limitations of classical diffusion tensor imaging. This paper presents an extensive study of high‐order models for apparent diffusion coefficient estimation and illustrates some of their applications. Using a meaningful modified spherical harmonics basis to capture the physical constraints of the problem, a new regularization algorithm is proposed. The new smoothing term is based on the Laplace–Beltrami operator and its closed form implementation is used in the fitting procedure. Next, the linear transformation between the coefficients of a spherical harmonic series of order ℓ and independent elements of a rank‐ℓ high‐order diffusion tensor is explicitly derived. This relation allows comparison of the state‐of‐the‐art anisotropy measures computed from spherical harmonics and tensor coefficients. Published results are reproduced accurately and it is also possible to recover voxels with isotropic, single fiber anisotropic, and multiple fiber anisotropic diffusion. Validation is performed on apparent diffusion coefficients from synthetic data, from a biological phantom, and from a human brain dataset. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Rapid cardiac‐output measurement with ungated spiral phase contrast
Authors: Park Jong B. , Hu Bob S. , Conolly Steven M. , Nayak Krishna S. , Nishimura Dwight G.
Published: June 2006

An ungated spiral phase‐contrast (USPC) method was used to measure cardiac output (CO) rapidly and conveniently. The USPC method, which was originally designed for small peripheral vessels, was modified to assess CO by measuring flow in the ascending aorta (AA). The modified USPC used a 12‐interleaf spiral trajectory to acquire full‐image data every 283 ms with 2‐mm spatial resolution. The total scan time was 5 s. For comparison, a triggered real‐time (TRT) method was used to indirectly calculate CO by measuring left‐ventricular (LV) volume. The USPC and TRT measurements from all normal volunteers agreed. In a patient with patent ductus arteriosus (PDA), high CO was measured with USPC, which agreed well with the invasive cardiac‐catheterized measurement. In normal volunteers, CO dropped about 20–30% with Valsalva maneuvering, and increased about 100% after exercise. Continuous 28‐s cycling between Valsalva maneuvering and free‐breathing showed that USPC can temporally resolve physiological CO changes. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Characterization of Mineral Building Materials by Mercury‐Intrusion Porosimetry
Authors: Rübner Katrin , Hoffmann Dirk
Published: June 2006

Mineral building materials are generally heterogeneous and porous solids. Their engineering properties are closely associated with their porosity and pore‐size distribution, which can be studied by mercury intrusion. The entire pore‐size distribution curves are used to determine changes in the pore structure of a material class in a qualitative way. Certain parameters derived from pore‐size distributions can be correlated to engineering properties. These key values are applied as criteria to evaluate the quality and durability of a building material. However, because of the heterogeneity of natural and artificial building materials and the influence of moisture content on their pore structure the results are strongly affected by preparation conditions such as sampling and drying. A correct analysis requires a knowledge of these effects. The paper describes the use of mercury porosimetry to study mineral building materials such as cementitious materials, bricks, and renderings. Furthermore, the influence of preparation effects on the precision of measurements is discussed.
Domain Complexion Diagrams Related to Mercury Intrusion‐Extrusion in Monte Carlo‐Simulated Porous Networks
Authors: Felipe Carlos , Cordero Salomón , Kornhauser Isaac , Zgrablich Giorgio , López Raul , Rojas Fernando
Published: June 2006

Porous networks of sites (cavities) and bonds (throats) are simulated by a Monte Carlo procedure; the connectivity (C) being the mean number of bonds surrounding a site. For simulating Hg intrusion‐extrusion processes, canthotaxis at site‐bond joints and snap‐off of Hg threads are considered. Hg porosimetry is illustrated in terms of domain complexion diagrams (DCD), these being graphs that depict the sites and bonds of given sizes that are either Hg‐filled or not. DCD plots show that during Hg intrusion: (i) the capillary resistance to Hg access becomes smaller as C increases, the bond sizes get larger, and canthotaxis is absent; (ii) in highly pore size correlated networks, the Hg filling sequence of sites occurs from the larger to the smaller voids; (iii) in lowly pore size correlated networks, Hg intrusion occurs homogeneously with respect to the whole set of site sizes. During extrusion, Hg entrapment is more intense when: (i) C is low, (ii) the pore size correlation is small, and (iii) the snap‐off phenomenon is extensive. Hg extrusion DCD plots show that for high C: (i) Hg is trapped inside the largest sites if the pore size correlation is null or medium; and (ii) at higher pore size correlations, Hg is retained over a wide range of site sizes. For networks of low C, Hg is trapped over a wide variety of cavity sizes irrespective of the pore size correlation.
Liquid Expulsion Permporometry – a Tool for Obtaining the Distribution of Flow‐Through Pores
Authors: Šolcová Olga , Hejtmánek Vladimír , Šnajdaufová Hana , Schneider Petr
Published: June 2006

The permporometry technique, common in the fields of thin filters, membranes etc., was extended to porous solids with far larger thicknesses. The basic idea of permporometry is the controlled expulsion of a suitable liquid from pores of different sizes by increasing the gas pressure difference across the tested porous solid. The gas flow rate through liquid‐free pores then corresponds to the amount of pores with different sizes. Two modes of measurement were suggested and tested. The contribution of the Knudsen flow mechanism was taken into account in addition to the usually anticipated viscous gas flow mechanism.

It was confirmed that both measurement modes give consistent pore size distributions (PSD) of flow‐through pores. Permporometry PSDs were compared with results from mercury porosimetry and pseudo‐steady state permeation. It appears that permporometry should be considered as a standard textural characterization technique suitable for the prediction and simulation of gas flow through porous media in all processes where gas transport takes place.
The Physical Significance of Mercury Porosity Hysteresis in the Characterization of Calcined Precipitated Alumina
Authors: Carruthers J. Donald
Published: June 2006

Activated alumina, for application as a catalyst support or as an adsorbent, is often obtained industrially via calcination of precipitated aluminum oxide hydrate. Its preparation conditions depend on the ultimate application, which, in turn, dictates its target specifications, e.g., surface area (SA), total pore volume (PV), pore size distribution (PSD) and density. Invariably, some method of porosity characterization is required periodically during manufacture for process control and at the final stage of alumina certification. Although gas and vapor adsorption methods were common in the early days of alumina production, mercury porosimetry (MP) has become the technique of choice in the past 30 years. MP provides valuable information about the meso‐ and macro‐pore structure of the alumina but the hysteresis, seen in each analysis, has been difficult to interpret. In this work the MP porosity of a wide variety of calcined aluminas is contrasted with thermogravimetric (TGA) analyses of the source aluminum oxide hydrates and the precipitation and activation conditions, which generated the aluminas in an attempt to better understand the hysteresis phenomenon. The results imply a “connectivity”, or internal structure, explanation for MP hysteresis in calcined aluminas.
Defining the fold space of membrane proteins: The CAMPS database
Authors: Martin‐Galiano Antonio J. , Frishman Dmitrij
Published: June 2006

Recent progress in structure determination techniques has led to a significant growth in the number of known membrane protein structures, and the first structural genomics projects focusing on membrane proteins have been initiated, warranting an investigation of appropriate bioinformatics strategies for optimal structural target selection for these molecules. What determines a membrane protein fold? How many membrane structures need to be solved to provide sufficient structural coverage of the membrane protein sequence space? We present the CAMPS database (Computational Analysis of the Membrane Protein Space) containing almost 45,000 proteins with three or more predicted transmembrane helices (TMH) from 120 bacterial species. This large set of membrane proteins was subjected to single‐linkage clustering using only sequence alignments covering at least 40% of the TMH present in a given family. This process yielded 266 sequence clusters with at least 15 members, roughly corresponding to membrane structural folds, sufficiently structurally homogeneous in terms of the variation of TMH number between individual sequences. These clusters were further subdivided into functionally homogeneous subclusters according to the COG (Clusters of Orthologous Groups) system as well as more stringently defined families sharing at least 30% identity. The CAMPS sequence clusters are thus designed to reflect three main levels of interest for structural genomics: fold, function, and modeling distance. We present a library of Hidden Markov Models (HMM) derived from sequence alignments of TMH at these three levels of sequence similarity. Given that 24 out of 266 clusters corresponding to membrane folds already have associated known structures, we estimate that 242 additional new structures, one for each remaining cluster, would provide structural coverage at the fold level of roughly 70% of prokaryotic membrane proteins belonging to the currently most populated families. Proteins 2006. © 2006 Wiley‐Liss, Inc.
One‐electron approach to describe charge and orbital order in Mn2OBO3
Authors: Matos M. , Oliveira R. B.
Published: June 2006

A detailed study is performed on the band structure of the mixed‐valent Mn2OBO3 warwickite, by using the high‐spin filling (hsf) scheme in the extended Hückel approach. It is found that charge ordering, found experimentally to be adopted by the compound, is associated with orbital order, represented by the presence of x2 − y2 holes in Mn1. The hsf scheme provides considerable improvement in the calculation of charge distribution in the material, as compared with the usual band filling scheme, with both Mn1 and Mn2 cations exhibiting positive charge. In addition, the octahedral distortion around Mn1 is correctly described as a Jahn–Teller (JT) type‐distortion. The calculated electronic band structure provides evidence that the Mn warwickite is an insulator, in agreement with experimental data. O1, connected to the JT‐like distortion of Mn1, is found to be loosely bound to the structure, as compared with other O‐atoms in the lattice, showing a favorable condition in the structural stability of the compound. Comparison is made with the mixed‐valent Fe2OBO3 warwickite. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Quark–boson molecular orbital calculations
Authors: Pavão Antonio C. , Ferreira Joacy V.
Published: June 2006

Ab initio molecular orbital calculations are performed on the system composed of a static three u(+2/3) quark core coupled to a b− boson cloud. Using appropriated Gaussian basis set functions to describe interactions at Fermi distances, this quark–boson system can be used as a proton model. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Application of the equivalent‐core calculation to the Cl in core level on condensed SiCl4
Authors: Mota G. V. S. , Costa F. L. P.
Published: June 2006

Utilization of the equivalent core may be of great help in the determination of excitation energies for condensed systems. This method presents a small difference in the excitation potential in relation to the experimental values, thus, enabling a better symmetry assignment for the excitations involved in the process. With the help of (Z+1)‐core model, we estimated the absorption position and the symmetry for the discrete core‐excitation state of the Cl K edge on SiCl4 and were able to understand the process of selective fragmentation for condensed systems with good calculation approximation. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Theoretical study of cooperative effects in the homo‐ and heteromeric hydrogen bond chains (HCN)nHF withn= 1, 2, and 3
Authors: Araújo Regiane C. M. U. , Soares Verneck M. , Oliveira Boaz G. , Lopes Kelson C. , Ventura Elizete , Do Monte Silmar A. , Santana Otávio L. , Carvalho Antônio B. , Ramos Mozart N.
Published: June 2006

Theoretical investigations concerning the formation of hydrogen bonds in both homomeric, (HCN)n, and heteromeric clusters of the type (HCN)nHF (n= 1, 2, and 3) have been performed through ab initio molecular orbital calculations at the second‐order Møller–Plesset (MP2) and density functional theory (DFT)/B3LYP levels, with the 6‐311++G(d,p) basis set. The formation of hydrogen bonds is investigated in terms of changes in structural, electronic, and vibrational parameters of the free species. Important parameters include the increment in the distance of the HF proton donor species, the increment in the HC distance of HCN moiety, and the amount of intermolecular charge transfer between the HCN species in the (HCN)ngroup. It is interesting to point out the different behavior in the HC distance as HCN acts simultaneously as a proton acceptor, proton donor, and a proton donor and acceptor. Other important results concern the cooperative effect (CE) in terms of the stabilization energy and dipole moment. Both CEs increase with cluster size and are more pronounced for the heteroclusters. The HF stretching frequency is red‐shifted on going in the direction (HCN)HF → (HCN)2HF → (HCN)3HF. This trend is in agreement with the following order of stabilization energies: ΔEHCN…HF< ΔE< ΔE. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Beyond demographics: Understanding the college experience through television
Authors: Tobolowsky Barbara F.
Published: June 2006

Understanding the prime‐time television portrait of college helps educators better understand the expectations our entering students may hold of college life.
Who will we serve in the future? The new student in transition
Authors: Lester Jaime
Published: June 2006

Hispanics are the fastest‐growing ethnic population in the United States. This chapter presents demographic projections for higher education and discusses the role of the transfer function in community colleges. Two notable transfer programs are highlighted.
International students in transition: Changes in access to U.S. higher education
Authors: Starobin Soko S.
Published: June 2006

This chapter presents the changes in recent international student enrollment in American higher education and examines policy issues affecting international students' access to colleges and universities. Implications for student services are discussed.
Increasing retention and success of students of color at research‐extensive universities
Authors: Aragon Steven R. , Rios Perez Mario
Published: June 2006

The number of students of color transferring to and completing degrees at four‐year, non‐research‐extensive universities continues to increase. However, research‐extensive universities struggle with recruiting and retaining students of color. This chapter discusses one initiative developed by a research‐extensive university focused on increasing success and graduation rates of students of color.
Forced transitions: The impact of natural disasters and other events on college students
Authors: Schuh John H. , Santos Laanan Frankie
Published: June 2006

This chapter presents a hypothetical situation related to students who are displaced by Hurricane Katrina. It focuses on transition issues for the students as they are relocated to a new college for an undetermined length of time.
Thermal and Structural Studies of a 1D Zinc(II) Coordination Polymer – [Zn(μ‐4,4′‐bipy)(H2O)4]n(CCl3COO)2n·(4,4′‐bipy)2n (4,4′‐bipy = 4,4′‐bipyridine), with Shorted Cl···Cl Interactions
Authors: Amiri Maryam Ghoreishi , Morsali Ali
Published: June 2006

A 1D ZnII(μ‐4,4′‐bipy) coordination polymer with trichloroacetate anions, [Zn(4,4′‐bipy)(H2O)4]n(CCl3COO)2n·(4,4′‐bipy)2n, has been synthesized, characterized and studied by thermal and X‐ray crystallography. The structural studies show the Zn atoms have a distorted octahedral environment. Self‐assembly of this compound in the solid state is likely caused by hydrogen boding, shorted Cl···Cl and π‐π stacking interactions.
The Binding Properties of Terminal and Bridging Fluoride and of Aqua Ligands – a Semiempirical Vibronic Coupling and DFT Study of Mixed‐Ligand Manganese(III) Complexes
Authors: Reinen Dirk , Atanasov Mihail , Massa Werner
Published: June 2006

A combined vibronic coupling and angular overlap analysis of MIIIL6 complexes, supplemented by basic DFT calculations, is performed where the 3d cations are CrIII, FeIII or the Jahn‐Teller unstable MnIII cation, and the ligands L fluoride – in terminal (Ft) or in bridging (Fb) function – or OH2. Our approach is mostly semiempirical and based on a novel ligand strain model, which utilises available structural and spectroscopic data and mostly deals with mixed‐ligand MnIII complexes, containing simultaneously Ft, Fb and H2O. Surveying the great number of published structural data, some interesting results concerning the differing binding properties are derived. While the total bond covalency is similar for the three ligands, the total bond strength – and hence also the ionic bond increment – follows the sequence: Ft ≫ OH2 > Fb. Partitioning the bond covalency into a part, which measures the ligand‐to‐metal charge flow (a), and an increment stemming from orbital (predominantly σ‐) overlap (b), one obtains: Ft ≫ Fb > OH2 for (a) and the reverse sequence for (b).

DFT model calculations on the [MIII(Ft)6]3− polyhedra in a solvent continuum were the basis for the elucidation of reliable ground state potential energy surfaces also for the further investigated complexes. The sometimes only very small energy difference between the involved three minima, generated via the interaction with the Jahn‐Teller active vibrational ϵg mode, led to various orthorhombic distortion conformers in the range between the tetragonal elongation and compression, depending on the strain magnitude imposed on the [Mn(Ft)6]3− parent polyhedron by a Ft‐by‐Fb (or OH2) substitution. It is further remarkable, that the average bond length of the Jahn‐Teller distorted octahedron varies significantly with the extent of the deformation and wether it is elongated or compressed – providing also computational evidence for the experimentally observed additional coupling to the totally symmetric α1g mode (Eg ⊗(ϵg + α1) vibronic interaction). The Jahn‐Teller stabilisation energy of the D4h‐elongated [MnIII(Ft)6]3− complex (absolute minimum) with respect to the regular octahedron can be defined as the difference between the non‐Jahn‐Teller restoring energy(≈ 0.3 eV) and the vibronic energy (≈ 0.65 eV). It is considerable (≈ −0.35 eV) in comparison to the stabilisation in regard to the compressed D4h‐conformer (≅ −0.075 eV).

DFT was not successful in calculating d‐d transition energies within the 5Eg ground state of MnIII complexes containing the aqua ligand. Apparently, hydrogen bonds of varying strength to the higher‐sphere chemical environment and with significant energetic retroaction on the MnIII‐OH2 bonds exist, which cannot be correctly simulated by non‐sophisticated DFT.
Synthesis, Spectral Properties and Crystal Structure of Calcium and Strontium Complexes of 1,10‐Phenanthroline
Authors: Neykov Mihail , van Almsick Tobias , Dimitrov Georgi
Published: June 2006

Three new complexes of 1,10‐Phenanthroline (phen), [Ca(phen)2(H2O)2(NO3)](NO3) (1), [Sr(phen)2(H2O)2(NO3)](NO3) (2) and [Ca(phen)2(H2O)2(NO3)][BF4] (3) were synthesized and characterized by UV, FT IR, Raman, and MS spectra. Their crystal structures were also determined. In 1 and 2 only one of the (NO3)− is coordinated to the central atom. The other (NO3)− is away from the metal ion and was replaced by [BF4]− under the conditions of a competitive reaction. The two phenanthroline molecules also occupy nonequivalent positions showing typical π – π interactions in their crystal packing.
The First Cadmium(II) Complex based on the 4‐Aminocinnamato Ligand with unusual 4.82 Topology
Authors: Zhang Qi‐Wei , Wen Yi‐Hang , Feng Yun‐Long
Published: June 2006

The first CdII complex based on the 4‐aminocinnamato ligand, [Cd3Cl2(OH)2(AC)2(H2O)2]n (1), (AC = 4‐aminocinnamato), has been synthesized by hydrothermal reaction and structurally determined. Complex 1 crystallizes in the monoclinic space group P21/c with cell parameters: a = 14.2599(10), b = 6.6329(5), c = 12.5568(10) Å, β = 95.069(4))°, V = 1183.03(15) Å3, Z = 2. Complex 1 consists of [Cd3Cl2(OH)2]n chains doubly bridged by AC ligands, forming a 2‐D network with unusual 4.82 topology. Hydrogen bonds between the layers result in the final 3D frameworks.
Synthesis and Structural Characterization of the Ammelinium Salts [C3H6N5O]Cl, [C3H6N5O]Br, and [C3H6N5O]NO3
Authors: Lotsch Bettina V. , Schnick Wolfgang
Published: June 2006

The salts ammelinium chloride [C3H6N5O]Cl, ammelinium bromide [C3H6N5O]Br, and ammelinium nitrate [C3H6N5O]NO3 were obtained by hydrolysis of melam hydrate with the respective concentrated mineral acids. The structures of the molecular salts were elucidated by single–crystal X–ray diffraction and vibrational spectroscopy, thus representing the first examples of structurally characterized ammeline derivatives. All ammeline salts crystallize in the monoclinic space group P21/c with 4 formula units in the unit cell. The hydrochloride (a = 5.354(2), b = 14.673(3), c = 8.152(2) Å, β = 90.00(3)°, V = 640.4(2) Å3, T = 293 K), hydrobromide (a = 5.212(1), b = 8.831(2), c = 14.577(3) Å, β = 98.97(3)°, V = 662.7(2) Å3, T = 130 K), and nitrate salt (a = 9.332(2), b = 6.256(2), c = 13.511(3) Å, β = 108.05(3)°, V = 750.0(3) Å3, T = 130 K) all contain planar, mono–protonated ammelinium cations which are hydrogeñbonded to the respective halide or nitrate anions. The noñisotypic structures are composed of anion – cation arrays forming either planar (chloride) or corrugated (nitrate) layers, or strands with differing stacking sense (bromide), respectively. Notably, the keto tautomer with C2v symmetry is representing the actual proton distribution rather than the hydroxy tautomer, which based on ab initio calculations has recently been predicted to be the more stable one for the parent base ammeline.
The First Complex of Diallylpolysulfide: Synthesis and Crystal Structure of [Cu3Br3(CH2=CH‐CH2‐(S)4‐CH2‐CH=CH2)]
Authors: Salivon N. F. , Filinchuk Y. E. , Olijnyk V. V.
Published: June 2006

A crystalline π‐complex [Cu3Br3(CH2=CH‐CH2‐(S)4‐CH2‐CH=CH2)] has been obtained by an alternating‐current electrochemical synthesis starting from CuBr2 and diallyltetrasulfide (DATS). Its structure is orthorhombic, space group Pbca, a = 9.9911(6), b = 23.2792(16), c = 12.8005(9) Å, V = 2977.2(3) Å3 (at 293 K), Z = 8; R1 = 0.0377, wR2 = 0.0760. The DATS molecule behaves as a bichelate pentadentate ligand: Cu1 atom is chelated by one of the two olefin groups and a weakly bonded sulfur atom, Cu3 atoms is chelated by two sulfur atoms and Cu2 is coordinated to the second olefin group. Centrosymmetric and pseudo‐centrosymmetric Cu2Br2 units are associated into a finite Cu6Br6 fragment by Cu…Br contacts of 3.116(1) Å.
Synthesis and Crystal Structure of Cobalt(II) and Cadmium(II) Complexes with the Flexible Tripodal Ligand 1,3,5‐Tris(4‐pyridylmethoxyl)benzene
Authors: Wu Gang , Zhang Zheng‐Hua , Okamura Taka‐aki , Sun Wei‐Yin , Ueyama Norikazu
Published: June 2006

Three complexes [Co(L4)(DMF)(H2O)(NO3)]NO3· DMF·0.5H2O (1), [Co(L4)2(SCN)2]·4CH3OH·H2O (2) and [Cd(L4)(bipy)(H2O)2](ClO4)2·4H2O (3) (DMF = N, N‐dimethylformamide, bipy = 4,4′‐bipyridine) were synthesized by reactions of ligand 1,3,5‐tris(4‐pyridylmethoxyl)benzene (L4) with the corresponding metal salts and their structures were determined by X‐ray single‐crystal structure analysis. Complex 1 crystallizes in monoclinic space group C2/c with cell parameters a = 26.200(9) Å, b = 17.465(5) Å, c = 17.275(5) Å, β = 118.183(10)°, V = 6968(4) Å3, Z = 8, while complexes 2 and 3 crystallize in triclinic space group $P{\bar 1}$ with different cell parameters, complex 2: a = 9.3077(7) Å, b = 14.7251(7) Å, c = 21.4745(13) Å, α = 70.380(4)°, β = 83.161(4)°, γ = 82.350(4)°, V = 2738.9(3) Å3, Z = 2; complex 3: a = 9.797(6) Å, b = 11.807(6) Å, c = 13.970(11) Å, α = 88.03(6)°, β = 88.77(6)°, γ = 74.53(5)°, V = 1556.4(17) Å3, Z = 1. In complexes 1, 2 and 3, all the metal atoms adopt distorted octahedral coordination, however, the ligand L4 have different coordination modes. In complex 1, the ligand acts as a three‐connected node to coordinate with three CoII atoms, and generate a doubly interpenetrated (10, 3)‐b three‐dimensional framework. In complex 2, each ligand L4 uses two of three arms to link two CoII atoms to form an infinite one‐dimensional hinged chain structure, while in complex 3, the L4 only serves as a terminal monodentate ligand.
Synthesis, Structure and Spectral Properties of [Ni(TAMEN)](ClO4)2·DMF (TAMEN = N,N′‐Tetra(4‐antipyryl‐methyl)‐1,2‐diaminoethane), a Mannich Base Complex of Biological Relevance
Authors: Tudose Ramona , Mosoarca Elena‐Maria , Pantenburg Ingo , Costişor Otilia , Meyer Gerd
Published: June 2006

The new mononuclear complex [Ni(TAMEN)](ClO4)2·DMF (TAMEN = N,N′‐tetra‐(4‐antipyrylmethyl)‐1,2‐diaminoethane) has been synthesized and its crystal structure was determined by single‐crystal X‐ray diffraction. It crystallizes with monoclinic symmetry, space group P21/c (no. 14) and unit cell parameters of a = 10.8736(3), b = 10.9560(4), c = 45.820(2) Å, β = 90.23(1)°, Z = 4. The TAMEN molecule acts as a hexadentate ligand incorporating a 1,2‐diaminoethane bridge in the staggered conformational gauche isomer. The nickel(II) ion is octahedrally coordinated with metal‐ligand distances ranging from 2.023(2) to 2.145(3) Å. Electronic and vibrational spectroscopy data agree well with the crystal structure.