bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mathematical Modeling of Size Exclusion Chromatography
Authors: Zelic B. , Nesek B. 
Published: March 2006

AbstractA mathematical model of the size exclusion chromatography (SEC) process in chromatographic columns has been developed. It considers the following three mass transfer processes in the SEC column: axial dispersion in the bulk‐fluid phase, interfacial film mass‐transfer between the stationary and mobile phases, and diffusion of solutes within the macro pores of the packing particles. Differential equations of the process model were solved by the finite difference method. Characteristics of the column and the packing particles (bed void volume fraction, particle porosity, accessible particle porosity) were obtained experimentally, as well as retention times of different molecules with known molecular weights. Experiments were performed with two different columns containing two different packing materials, Superdex 75 HR 10/30 and BioSep SEC S2000, respectively. The model has been validated by comparing theoretical and experimental retention times for the different columns.
Comparison of the power of the tests in one‐way ANOVA type model with Poisson distributed variables
Authors: Hrdličková Zuzana 
Published: March 2006

AbstractThis article deals with the one‐way ANOVA type generalized linear model, the method most often used if the assumptions of the classical one‐way ANOVA are not satisfied. In particular, the model with Poisson distributed response variables is considered. The article aims at the powers of tests based on the most frequent statistics—deviance, Pearson and score statistic. The asymptotic powers of the considered tests are obtained either analytically or by means of simulation. Afterwards, these powers are compared with powers of the tests obtained by an alternative method—a variance‐stabilizing transformation followed by the classical linear model with known or unknown variance. Finally, a power analysis is carried out on biometrical data to find an experimental design suitable for detecting a priory given differences in expected values. Copyright © 2006 John Wiley & Sons, Ltd.
A Web‐based rainfall atlas for Southern Africa
Authors: Zucchini Walter , Nenadić Oleg 
Published: March 2006

AbstractWe describe the development of a Web‐based rainfall atlas for southern Africa, a decision support system for the management of water resources. The rainfall atlas, which is accessible online at the URIhttp://134.76.173.220/rainfall/index.html, was constructed in a number of phases over some 20 years. In the first phase, a 16 parameter model was developed, validated for representative sites, and then fitted to daily rainfall data from 2550 sites. Eight years later the estimates of the model parameters were updated, extended to 5070 sites, and interpolated on a grid of 1 minute of a degree of latitude and longitude over the entire region of southern Africa, namely South Africa, Lesotho and Swaziland. The method of kriging with external drift was used for the interpolation. The interpolated estimates were used to generate long artificial daily rainfall sequences at a spatial resolution of 1 minute of degree square. The sequences were used to compute rainfall‐related statistics, such as percentiles of annual and monthly rainfall distributions, probabilities associated with droughts, and additional measures relating to the timing and intensity of rainfall. The final phase, information transfer, was the construction of the Atlas website, which offers online access to a wide range of rainfall‐related statistics and some 5000 maps. To facilitate the computation of statistics that are not available in the database, the Atlas enables users to generate, and then import, artificial sequences online, for any grid point in southern Africa. These sequences are designed to mirror the properties of real rainfall records (seasonality, serial dependence, distributional properties, etc.) at the required grid point and can be used to compute quantities of interest empirically. Copyright © 2006 John Wiley & Sons, Ltd.
Pattern analysis of dune‐field parameters
Authors: Ewing Ryan C. , Kocurek Gary , Lake Larry W. 
Published: March 2006

AbstractAs a basic form of pattern analysis, the parameters of dune spacing, defect density, crest orientation and crest length are measured from remote images and treated statistically for dunes at White Sands in New Mexico, the Algodones in California, the Agneitir in Mauritania, and the Namib in Namibia. Statistical populations are identified from frequency plots of dune spacing and crest length, field‐scale calculations of defect density, and rose diagrams of crest orientation. Single populations characterize simple dune fields (White Sands), whereas multiple populations characterize compound/complex dunes (Algodones, Namib), and complex dune fields (Agneitir). As time increases, dune fields show an increase in dune spacing and crest length, a decrease in defect density, more tightly clustered crest orientation, and a reduction in the variance associated with measurements of these parameters. The results are consistent with models of dune fields as self‐organizing complex systems in which a characteristic pattern emerges as a function of constructional time. Because pattern evolution is a function of time, it may be possible to use pattern analysis to augment current methods of age determination. Statistically defined populations can be used in geomorphic backstripping to unstack generations of simple patterns that give rise to complex patterns, and to reconstruct each generation in terms of construction time and palaeo‐wind regime. Copyright © 2006 John Wiley & Sons, Ltd.
Ten Years (1994–2004) of ‘potential’ weathering in Kärkevagge, Swedish Lapland
Authors: Thorn Colin E. , Dixon John C. , Darmody Robert G. , Allen Charles E. 
Published: March 2006

AbstractThis paper reports the findings of a ten‐year study of ‘potential’ weathering of machine‐polished dolomite, granite and limestone discs buried in shallow pits beneath a variety of vegetation cover types in Kärkevagge and on an adjoining ridge in Swedish Lapland. The paper extends a previously published five‐year (1994–1999) record by adding the period 1999–2004, comparing the two periods, and integrating results to provide a decadal record. The field and laboratory procedures of the first period were faithfully replicated during the second period with the notable modification that only a segment of each original disc was replaced in the field for the second portion of the study. A total of 48 dolomite, 36 granite and 19 limestone discs were buried at shallow depths (≤60 cm) beneath alpine tundra, birch forest, Dryas heath, heath, meadow, solifluction meadow and willow cover types. With the exception of the willow, which had only two, each cover type had three replicated pits.Relationships identified during Period 1 were generally repeated during Period 2. Salient results are the expected weathering rate order of limestone > dolomite > granite, and statistically distinguishable differences in weathering rate by vegetation cover type. Differentiation of the two heath categories from the other vegetation cover types is the most important spatial distinction in weathering rate. Statistical distinctions among other measures were variable, with soil horizon and burial depth being non‐significant, pH variability being weakly distinguishable, and drainage variability being important. Granite mass losses were generally too low to be useful for statistical separation. Dolomite discs experienced a statically higher loss rate during Period 2 which had both a warmer and wetter air climate than Period 1. Minimum and maximum total decadal percentage losses from the discs were 0·2 and 25·7 for dolomite, 0·07 and 0·57 for granite, and 0·2 and 32·1 for limestone. In general, dolomite was the most useful material for monitoring mass loss, with limestone weathering tending to be too rapid and granite weathering being too slow. Copyright © 2006 John Wiley & Sons, Ltd.
Contribution to understanding the historical evolution of meandering rivers using dendrochronological methods: example of the Mała Panew River in southern Poland
Authors: Malik Ireneusz 
Published: March 2006

AbstractThe Mała Panew is a meandering river that flows 20 km through a closed forest. During times of high discharge the riverbed and floodplain are transformed under the influence of riparian trees. The changes provide the opportunity to measure the intensity of erosion and sediment accumulation based on tree ages, the dating of coarse woody debris (CWD) in the riverbed, and the dating of eccentric growth of tilting trees and exposed roots.The bed and floodplain in reaches of the Mała Panew River with low banks were greatly altered as a result of long periods of flooding between 1960 and 1975. Banks were undercut during these floods and black alders tilted. Those parts of alder crowns or stems which tilt and sink generate small sand shadows. When erosion is intensive alder clumps are undercut from concave banks and become mid‐channel islands, while on the other side of the channel meandering bar levels are created.The reaches with higher banks were altered by large floods, especially in 1985 and 1997. The concave banks are undercut and sediment with CWD is deposited within the riverbed, forming sand shadows behind the CWD. Copyright © 2006 John Wiley & Sons, Ltd.
An educative, values‐engaged approach to evaluating STEM educational programs
Authors: Greene Jennifer C. , DeStefano Lizanne , Burgon Holli , Hall Jori 
Published: March 2006

AbstractThe major principles and commitments of an educative, values‐engaged approach to STEM educational program evaluation are presented, justified, and illustrated. How this approach addresses key issues in STEM education and advances the field is also discussed.
Biomaterials and scaffolds for ligament tissue engineering
Authors: Ge Zigang , Yang Fang , Goh James C. H. , Ramakrishna Seeram , Lee Eng Hin 
Published: March 2006

AbstractTissue engineering has achieved much progress in an attempt to improve and recover impaired functions of tissues and organs. Although many studies have been done, progress for tissue‐engineered anterior cruciate ligaments (ACLs) has been slow due to their complex structures and mechanical properties. In this review, the ACL anatomical structure, progresses achieved, material selection, structure design, and future direction have been discussed, while the challenges and requirements from materials and scaffolds are highlighted. There is a considerably huge amount work that needs to be carried out; as such, future direction in ligament tissue engineering is proposed in hope that this review will give information on future ligament tissue engineering. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 2006
Repair of 20‐mm long rabbit radial bone defects using BMP‐derived peptide combined with an α‐tricalcium phosphate scaffold
Authors: Saito Atsuhiro , Suzuki Yoshihisa , Kitamura Makoto , Ogata Shin‐Ichi , Yoshihara Yusuke , Masuda Shingo , Ohtsuki Chikara , Tanihara Masao 
Published: March 2006

AbstractIn previous studies, we have reported that the BMP‐2‐derived peptide KIPKASSVPTELSAISTLYL, corresponding to BMP‐2 residues 73–92, binds to a BMP‐2‐specific receptor, and elevates both alkaline phosphatase activity and osteocalcin mRNA in the murine mesenchymal cell line, C3H10T1/2. This 73–92 peptide conjugated to a covalently crosslinked alginate gel induced ectopic bone formation in rat calf muscle, and activated osteoblasts to promote the repair of rat tibial bone defects. Here, we report repair of 20‐mm long rabbit radial bone defects using the 73–92 peptide combined with a porous α‐tricalcium phosphate (TCP) scaffold. In vitro, the 73–92 peptide was released from the porous α‐TCP scaffold over more than one week. In vivo, radiomorphometric analysis showed that the 73–92 peptide combined with the porous α‐TCP scaffold promoted calcification in the implanted area in a dose‐dependent manner, and that 5 mg of the 73–92 peptide induced connection of 20‐mm long defects, defects of critical size, 12 weeks after implantation. Histological examination revealed newly formed bone and a marrow cavity in the implanted area. The area of bone denser than 690 mg/cm3 induced by the 73–92 peptide was nearly equal to that of the contralateral radius. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Osteoinduction by biomaterials—Physicochemical and structural influences
Authors: Habibovic Pamela , Sees Tara M. , van den Doel Mirella A. , van Blitterswijk Clemens A. , de Groot Klaas 
Published: March 2006

AbstractOsteoinduction by biomaterials has been shown to be a real phenomenon by many investigators in the last decade. The exact mechanism of this phenomenon is, however, still largely unknown. This in vivo study in goats was performed to get insight into processes governing the phenomenon of osteoinduction by biomaterials and had four main goals: (i) to further investigate the influence of physicochemical properties and structure on biomaterial osteoinductive potential, (ii) to investigate the influence of implant size on the amount of induced bone, (iii) to investigate implantation site dependence, and (iv) to investigate changes occurring on the surface of the material after implantation. Intramuscular implantations of four different biphasic calcium phosphate ceramics, consisting of hydroxyapatite and β‐tricalcium phosphate and a carbonated apatite ceramic, indicated that, for a maximal osteoinductive potential, there is an optimal specific surface area for each material type. It was further shown that a decrease of the implant size with a half significantly decreased the relative amount of induced bone. In addition, subcutaneous implantation did not give rise to ectopic bone formation in any of the animals, while bone was induced in most animals intramuscularly. Analysis of the surfaces of the materials after subcutaneous implantation inside diffusion chambers indicated that the increased specific surface area leads to more surface reactivity, which is hypothesized to be essential for osteoinductivity by biomaterials. © 2006 Wiley Periodicals, Inc. J Biomed Master Res, 2006
Linear‐scaling molecular orbital calculations for the pKa values of ionizable residues in proteins
Authors: Ohno Kazuki , Sakurai Minoru 
Published: March 2006

AbstractIn this report, we present a computational methodology for the pKa prediction of proteins, based on linear‐scaling molecular orbital calculations for their solution‐conformations obtained from NMR measurements. The method is used to predict the pKa values of five carboxylic acids (Asp7, Glu10, Glu19, Asp27, and Glu43) in turkey ovomucoid third domain (OMTKY3), and six aspartates residues (Asp 22, Asp 44, Asp 54, Asp 75, Asp 83, and Asp 93) in barnase. For OMTKY3, all the predicted pKa values are within 1 pH units from the available experimental ones, except for the case of Glu 43. For barnase, the root‐mean‐square deviation from experiment is 1.46 pH units. As a result, the proposed pKa calculation method correctly reproduces the relative order of the pKa values among the carboxylic acids located in different sites of the proteins. The calculated pKa values are decomposed into the contributions of short‐ and long‐range structural difference effects. The results indicate that in both proteins the pKa value of the given carboxylic acid is partially influenced by long‐range interactions with distant charged residues, which significantly contribute to determining the relative order of the pKa values. The current methodology based on LSMO provides us useful information about the titration behavior in a protein. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 906–916, 2006
Theoretical study on the mechanism of the CH2F + NO2 reaction
Authors: Zhang Jia‐Xu , Li Ze‐Sheng , Liu Jing‐Yao , Sun Chia‐Chung 
Published: March 2006

AbstractDespite the importance of the Fluoromethyl radicals in combustion chemistry, very little experimental information on their reactions toward stable molecules is available in the literature. Motivated by recent laboratory characterization about the reaction kinetics of Chloromethyl radicals with NO2, we carried out a detailed potential energy survey on the CH2F + NO2 reaction at the B3LYP/6‐311G(d,p) and MC‐QCISD (single‐point) levels as an attempt toward understanding the CH2F + NO2 reaction mechanism. It is shown that the CH2F radical can react with NO2 to barrierlessly generate adduct a (H2FCNO2), followed by isomerization to b1 (H2FCONO‐trans) which can easily interconvert to b2 (H2FCONO‐cis). Subsequently, Starting from b (b1, b2), the most feasible pathway is the CF and NO1 bonds cleavage along with NF bond formation of b (b1, b2) leading to P1 (CH2O + FNO), or the direct NO1 weak‐bond fission of b (b1, b2) to give P2 (CH2FO + NO), or the 1,3‐H‐shift associated with NO1 bond rupture of b1 to form P3 (CHFO + HNO), all of which may have comparable contribution to the reaction CH2F + NO2. Much less competitively, b2 either take the 1,4‐H‐shift and O1N bond cleavage to form product P4 (CHFO + HON) or undergo a concerted H‐shift to isomer c2 (HFCONOH), followed by dissociation to P4. Because the rate‐determining transition state (TSab1) in the most competitive channels is only 0.3 kcal/mol higher than the reactants in energy, the CH2F + NO2 reaction is expected to be rapid, and may thus be expected to significantly contribute to elimination of nitrogen dioxide pollutants. The similarities and discrepancies among the CH2X + NO2 (X = H, F, and Cl) reactions are discussed in terms of the electronegativity of halogen atom. The present article may assist in future experimental identification of the product distributions for the title reaction, and may be helpful for understanding the halogenated methyl chemistry. © 2006 Wiley Periodicals, Inc. J Comput Chem 27: 894–905, 2006
Ethylene glycol diglycidyl ether as a protein cross‐linker: a case study for cross‐linking of hemoglobin
Authors: Lu Xiuling , Xu Yuhong , Zheng Chunyang , Zhang Guifeng , Su Zhiguo 
Published: March 2006

AbstractBeing widely applied in the chemical industry, ethylene glycol diglycidyl ether (EGDE) was tried as a protein cross‐linker for cross‐linking of bovine hemoglobin (Hb). The characteristics of the reaction and the products were studied using electrophoresis and multi‐angle laser light scattering coupled with HPLC. At pH 7.5, EGDE could react with the sulfhydryl group and the ε‐amino group, but reacted preferentially with the sulfhydryl group. As the pH increased from 7.5 to 9.5, the reaction took place mainly between the amino groups and EGDE. By controlling the pH and other conditions, intra‐ and inter‐molecularly cross‐linked products with narrow size distribution were obtained. The intramolecular product was about 90% of the reaction mixture. The intermolecularly cross‐linked Hb consisted of 74.7% of dimeric Hb with weight‐average molecular weights (Mw) of 146 kDa, 18.9% of trimeric Hb with Mw of 228 kDa, and 6.4% of oligomer with four to six Hb units, Mw of 375 kDa. The cross‐linking altered the oxygen affinity (P50) and the Hill coefficient of Hb but they are within the range of hemoglobin‐based red cell substitutes. The pI of intramolecularly and intermolecularly cross‐linked Hb increased from 6.7–7.4 to 6.9–7.6 and 8.2–8.8 respectively. The study demonstrated that EGDE could be an alternative to glutaraldehyde for cross‐linking of hemoglobin and other proteins on a large‐scale without significantly impairing the biological activity. Copyright © 2006 Society of Chemical Industry
Enhanced photodegradation of bisphenol A in the presence of β‐cyclodextrin under UV light
Authors: Wang Guanghui , Wu Feng , Zhang Xu , Luo Mingdao , Deng Nansheng 
Published: March 2006

AbstractEnhancement of the photodegradation of bisphenol A (BPA) by β‐cyclodextrin (β‐CD) was investigated under a 30 W UV disinfection lamp (λmax = 254 nm). The photodegradation rate of BPA in aqueous solutions with β‐CD was faster than that in aqueous solutions without β‐CD; for example, after 50 min of UV irradiation, β‐CD had increased the photodegradation efficiency by about 46.5% for 10 mg dm−3 BPA. The photodegradation of 2.5–20 mg dm−3 BPA in aqueous solutions was found to follow pseudo‐first‐order kinetics. The first‐order rate constant showed a 12‐fold increase in the presence of β‐CD. Factors such as β‐CD concentration, pH, BPA initial concentration and organic solvent influencing the photodegradation of BPA were studied and are described in detail. Variations in the pH and electrical conductivity of solutions were observed during the photodegradation process. The enhancement of photodegradation of BPA results mainly from the lower bond energy between some atoms in the BPA molecule after inclusion interaction with β‐CD. Copyright © 2006 Society of Chemical Industry
Multidecadal climate variability of global lands and oceans
Authors: McCabe Gregory J. , Palecki Michael A. 
Published: March 2006

AbstractPrincipal components analysis (PCA) and singular value decomposition (SVD) are used to identify the primary modes of decadal and multidecadal variability in annual global Palmer Drought Severity Index (PDSI) values and sea‐surface temperatures (SSTs). The PDSI and SST data for 1925–2003 were detrended and smoothed (with a 10‐year moving average) to isolate the decadal and multidecadal variability. The first two principal components (PCs) of the PDSI PCA explained almost 38% of the decadal and multidecadal variance in the detrended and smoothed global annual PDSI data. The first two PCs of detrended and smoothed global annual SSTs explained nearly 56% of the decadal variability in global SSTs. The PDSI PCs and the SST PCs are directly correlated in a pairwise fashion. The first PDSI and SST PCs reflect variability of the detrended and smoothed annual Pacific Decadal Oscillation (PDO), as well as detrended and smoothed annual Indian Ocean SSTs. The second set of PCs is strongly associated with the Atlantic Multidecadal Oscillation (AMO). The SVD analysis of the cross‐covariance of the PDSI and SST data confirmed the close link between the PDSI and SST modes of decadal and multidecadal variation and provided a verification of the PCA results. These findings indicate that the major modes of multidecadal variations in SSTs and land‐surface climate conditions are highly interrelated through a small number of spatially complex but slowly varying teleconnections. Therefore, these relations may be adaptable to providing improved baseline conditions for seasonal climate forecasting. Copyright © 2006 John Wiley & Sons, Ltd.