bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analyte‐Induced Aggregation of a Water‐Soluble Conjugated Polymer for Fluorescent Assay of Oxalic Acid
Authors: Sun Huan , Feng Fude , Yu Minghui , Wang Shu 
Published: August 2007

AbstractAn assay method has been developed to detect oxalic acid from other structurally similar dicarboxylic acids using a cationic polythiophene derivative (PFT). Upon adding oxalic acid, the PFT can be cross‐linked through the bifunctional diacids of oxalic acid to form tense interpolymer π‐stacking aggregation, which results in the fluorescence self‐quenching of the PFT. Upon adding other dicarboxylic acids with a longer tether, loose interpolymer π‐stacking aggregation forms and the PFT fluorescence is less quenched. The fluorescence analysis was carried out in solution for the aggregates prior to precipitation. As a result of the short tether of oxalic acid, the unique fluorescent response from the PFT/oxalic acid assembly can be used to detect oxalic acid.magnified image
Prediction of the Bivariate Molecular Weight‐Long Chain Branching Distribution in High‐Pressure Low‐Density Polyethylene Autoclaves
Authors: Krallis Apostolos , Pladis Prokopis , Kiparissides Costas 
Published: August 2007

AbstractIn the present study a population balance approach is described to follow the time evolution of bivariate molecular weight‐long chain branching (MW‐LCB) distributions in high pressure low density polyethylene autoclaves. The model formulation is based on a sectional grid method, the so‐called fixed pivot technique (FPT). According to this method, the ‘live’ and ‘dead’ polymer chain populations are assigned to a selected number of discrete points. Then, the resulting dynamic discrete‐continuous molar species equations for ‘live’ and ‘dead’ polymer chains are solved at the specified grid points. It is shown that a very good agreement exists between theoretical results and experimental data which proves the capability of the FPT method in calculating the joint MW‐LCB distribution for branched polymers.magnified image
Spinodal Decomposition in Ternary Systems with Significantly Different Component Diffusivities
Authors: Alfarraj Abdulrahman A. , Nauman E. Bruce 
Published: August 2007

AbstractA numerical method for simulating spinodal decomposition in ternary systems with order‐of‐magnitude differences in diffusion coefficients is presented. The method has been partially verified by molecular dynamic simulations and gives results equivalent to the standard technique when the diffusivities are equal. A two‐dimensional simulation of an asymmetric polymer/polymer/polymer system reproduces an experimentally observed bimodal distribution of dispersed‐phase particle sizes. The ripening exponent for the larger particles is near the expected value of 0.33, but that for the smaller particles is only about 0.1. The method was also used for a polymer/polymer/solvent system.magnified image
Uncertainty and choice: the challenges of pharmaceutical efficacy, safety, and cost
Authors: Scherer F.M. 
Published: August 2007

AbstractThis paper addresses the role of uncertainty in challenges confronting the US pharmaceutical industry and its regulators. It begins with a macroeconomic overview, showing how rising health care costs, including rising ethical drug costs, squeeze the wage and salary share of national income. It addresses the claim that pharmaceutical companies' new drug pipelines are drying up. Taking a stochastic approach, it shows that both the trend of new medical entity approvals and the trend of pharmaceutical company gross margins can be explained as random walks—the latter as a result of sampling from a highly skew distribution. It then focuses on problems of ascertaining efficacy and especially low‐probability adverse effects from clinical trial samples of acceptable size. Noting the need for post‐NDA surveillance of adverse effects and observing the incentive failures that occur at that stage, it proposes two new approaches to identifying adverse reactions. Copyright © 2007 John Wiley & Sons, Ltd.
Entry and competition in generic biologics
Authors: Grabowski Henry G. , Ridley David B. , Schulman Kevin A. 
Published: August 2007

AbstractPatents for several blockbuster biological products are expected to expire soon. The Food and Drug Administration is examining whether biologics can and should be treated like pharmaceuticals with regard to generics. In contrast with pharmaceuticals, which are manufactured through chemical synthesis, biologics are manufactured through fermentation, a process that is more variable and costly. Regulators might require extensive clinical testing of generic biologics to demonstrate equivalence to the branded product. The focus of the debate on generic biologics has been on legal and health concerns, but there are important economic implications. We combine a theoretical model of generic biologics with regression estimates from generic pharmaceuticals to estimate market entry and prices in the generic biologic market. We find that generic biologics will have high fixed costs from clinical testing and from manufacturing, so there will be less entry than would be expected for generic pharmaceuticals. With fewer generic competitors, generic biologics will be relatively close in price to branded biologics. Policy makers should be prudent in estimating financial benefits of generic biologics for consumers and payers. We also examine possible government strategies to promote generic competition. Copyright © 2007 John Wiley & Sons, Ltd.
Benefits and costs of newer drugs: an update
Authors: Lichtenberg Frank R. 
Published: August 2007

AbstractIn previous work, we found strong evidence to support the hypothesis that the replacement of older drugs by new drugs resulted in reductions in total medical expenditures. In this study, we update and extend our previous study of the effect of drug age—years since FDA approval—on total medical expenditure, in several respects: (1) the unit of analysis is a medical condition, rather than a prescription; (2) the sample is much larger, including data for 3 years, rather than 1 year; (3) we obtain estimates for the Medicare population as well as for the entire population; and (4) within the Medicare population, we examine the effect of drug age on Medicare expenditure as well as on expenditure by all payers.The estimates indicate that, in the entire population, a reduction in the age of drugs utilized reduces non‐drug expenditure 7.2 times as much as it increases drug expenditure. For example, reducing the mean age of drugs used to treat a condition from 15 years to 5.5 years is estimated to increase prescription drug spending by $18 but reduce other medical spending by $129, yielding a $111 net reduction in total health spending. Most of the savings are due to reductions in hospital expenditure ($80) and in physician office‐visit expenditures ($24).In the Medicare population, a reduction in the age of drugs utilized reduces non‐drug expenditure by all payers (i.e. Medicare and various forms of Medicare supplemental insurance, Medicare for dually eligible individuals and Medicare beneficiaries' out of pocket payments) 8.3 times as much as it increases drug expenditure; it reduces Medicare non‐drug expenditure 6.0 times as much as it increases drug expenditure. About two‐thirds of the non‐drug Medicare cost reduction is due to reduced hospital costs. The remaining third is approximately evenly divided between reduced Medicare home health care cost and reduced Medicare office‐visit cost.We also show that Medicare enrollees with private prescription drug coverage tend to use newer drugs than those without such coverage: the mean age of drugs used by Medicare enrollees with private Rx insurance is about 9% lower than the mean age of drugs used by Medicare enrollees without either private or public Rx insurance. Copyright © 2007 John Wiley & Sons, Ltd.
Rx Roulette: combatting counterfeit pharmaceuticals in developing nations
Authors: Lybecker Kristina M. 
Published: August 2007

AbstractThe debate over access to medicines has principally centered on pharmaceutical patents and prohibitively high drug prices. Although a less recognized problem, counterfeit pharmaceuticals are certainly a more insidious barrier to access. Pharmaceutical counterfeiting is an invisible threat, not only by nature, but also because the industry has historically downplayed it. However, that has changed. Pharmaceutical firms now not only readily concede counterfeiting is a threat to their business, but in some cases publicly address their strategies and the anticounterfeiting technologies in use and development. Acknowledging the problem has benefited the industry because it alters the ways in which firms are able to combat counterfeiting, allowing them to more overtly confront the problem. In addition, it allows them to better partner with governments and health advocates since their incentives are aligned in efforts to prevent counterfeiting. In light of the more public and more aggressive campaign against counterfeiting, it is important to examine the variety of strategies firms may utilize to prevent their sale. Through a theoretical model of the market in a representative developing country, several anticounterfeiting strategies are considered. Some strategies appear to be more effective than others in the battle against fake drugs. Copyright © 2007 John Wiley & Sons, Ltd.
The cost of biopharmaceutical R&D: is biotech different?
Authors: DiMasi Joseph A. , Grabowski Henry G. 
Published: August 2007

AbstractThe costs of developing the types of new drugs that have been pursued by traditional pharmaceutical firms have been estimated in a number of studies. However, similar analyses have not been published on the costs of developing the types of molecules on which biotech firms have focused. This study represents a first attempt to get a sense for the magnitude of the R&D costs associated with the discovery and development of new therapeutic biopharmaceuticals (specifically, recombinant proteins and monoclonal antibodies [mAbs]).We utilize drug‐specific data on cash outlays, development times, and success in obtaining regulatory marketing approval to estimate the average pre‐tax R&D resource cost for biopharmaceuticals up to the point of initial US marketing approval (in year 2005 dollars). We found average out‐of‐pocket (cash outlay) cost estimates per approved biopharmaceutical of $198 million, $361 million, and $559 million for the preclinical period, the clinical period, and in total, respectively. Including the time costs associated with biopharmaceutical R&D, we found average capitalized cost estimates per approved biopharmaceutical of $615 million, $626 million, and $1241 million for the preclinical period, the clinical period, and in total, respectively. Adjusting previously published estimates of R&D costs for traditional pharmaceutical firms by using past growth rates for pharmaceutical company costs to correspond to the more recent period to which our biopharmaceutical data apply, we found that total out‐of‐pocket cost per approved biopharmaceutical was somewhat lower than for the pharmaceutical company data ($559 million vs $672 million). However, estimated total capitalized cost per approved new molecule was nearly the same for biopharmaceuticals as for the adjusted pharmaceutical company data ($1241 million versus $1318 million). The results should be viewed with some caution for now given a limited number of biopharmaceutical molecules with data on cash outlays, different therapeutic class distributions for biopharmaceuticals and for pharmaceutical company drugs, and uncertainty about whether recent growth rates in pharmaceutical company costs are different from immediate past growth rates. Copyright © 2007 John Wiley & Sons, Ltd.
Nostalgia and giving to charity: a conceptual framework for discussion and research
Authors: Merchant Altaf , Ford John 
Published: August 2007

AbstractAcademic work involving nostalgia has shown it to evoke a basket of emotions. This paper proposes a conceptual model that links nostalgia to charitable giving. We argue that the nostalgia evoked by certain NPOs (not‐for‐profit organizations) is likely to have a bearing on both emotional and familial utility derived by the donor. This in turn is likely to drive the donor commitment to the NPO. Thus by evoking nostalgia, certain NPOs are likely to emotionally engage their current and potential donors, which could facilitate the creation of long‐term intimate relationships between them and their donors. However, the extent to which the NPO can evoke nostalgia is likely to depend upon the nostalgia proneness of the donor, the emotional importance of the past experiences evoked by the NPO, and the characteristics of the NPO such as the extent to which the NPO can alleviate the feelings of alienation, discontinuity, and the need for authenticity experienced by the donor. The paper provides a series of research propositions and proposes a research agenda.Copyright © 2007 John Wiley & Sons, Ltd.
Preconceptional and prenatal screening for fragile X syndrome: Experience with 40 000 tests
Authors: Berkenstadt Michal , Ries‐Levavi Liat , Cuckle Howard , Peleg Leah , Barkai Gad 
Published: August 2007

AbstractObjectivesTo determine the carrier frequency of fragile X syndrome, and the rate of expansion from premutation (PM) carrier to full mutation (FM) fetus.MethodsResults were analyzed on women with no family history of fragile X syndrome, or who were PM/FM carriers, who were tested between January 1994 and June 2004.PM was defined 55–199 repeats, FM above 200.ResultsOut of 40 079 women screened, 5 FM and 255 PM carriers were detected. There was no significant difference in carrier frequency between those with versus those without family history of mental retardation or developmental abnormalities: 1 in 128 (28/3596) versus 1 in 157 (232/36 483). However, the median of repeats differed significantly: 58 and 66 repeats, respectively, (P < 0.0001). Invasive prenatal diagnosis was carried out in 370 pregnancies (7 FM and 363 PM). Thirty FM fetuses were detected. There was a lower expansion rate in cases without a family history: 10% (17/169 PMs) compared to 50% (11/22 PMs) in those with a history, but this could be accounted for by the difference in allele size.ConclusionThere is now sufficient information on screening parameters and prenatal diagnosis of fragile X syndrome to offer testing to women of reproductive age. Copyright © 2007 John Wiley & Sons, Ltd.
Methods, algorithms and tools in computational proteomics: A practical point of view
Authors: Matthiesen Rune 
Published: August 2007

AbstractComputational MS‐based proteomics is an emerging field arising from the demand of high throughput analysis in numerous large‐scale experimental proteomics projects. The review provides a broad overview of a number of computational tools available for data analysis of MS‐based proteomics data and gives appropriate literature references to detailed description of algorithms. The review provides, to some extent, discussion of algorithms and methods for peptide and protein identification using MS data, quantitative proteomics, and data storage. The hope is that it will stimulate discussion and further development in computational proteomics. Computational proteomics deserves more scientific attention. There are far fewer computational tools and methods available for proteomics compared to the number of microarray tools, despite the fact that data analysis in proteomics is much more complex than microarray analysis.
Surfactant‐assisted specific‐acid catalysis of Diels–Alder reactions in aqueous media
Authors: Mubofu Egid B. , Engberts Jan B.F.N. 
Published: August 2007

AbstractSurfactant‐assisted specific‐acid catalysis (SASAC) for Diels–Alder reactions of dienophiles 1 and 4 with cyclopentadiene 2 in aqueous media at 32 °C was studied. This study showed that acidified anionic surfactants (pH 2) such as sodium dodecyl sulfate (SDS) and linear alkylbenzene sulfonic acid (LAS) accelerate Diels—Alder reactions. Conversely, under similar reaction conditions (pH 2) these reactions are inhibited by (acidified) cationic surfactants such as dodecyltrimethylammonium bromide (DTAB), dodecyldimethylammonium bromide (DDAB), and dodecylmethylammonium bromide (DMAB). A modest rate acceleration resulting from the surfactant hydrogen‐bonding capacity is also recorded for the Diels–Alder reaction of naphthoquinones (6) with cyclopentadiene (2) in aqueous media at 32 °C. Copyright © 2007 John Wiley & Sons, Ltd.
The nature of the electronic factor governing diastereofacial selectivity in remotely substituted (X) 2‐adamantyl cations: 5‐X versus 4‐X substitution
Authors: Adcock William , Trout Neil A. 
Published: August 2007

AbstractA limited series of 4eq‐substituted (X) 2‐methyleneadamantanes (6, YCH2, XF, Cl, Br, I, and SnMe3) has been synthesized and diastereoselectivities for their hydrochlorination (HCl/CH2Cl2) have been determined. Diastereoselectivities for the fluorination (DAST/CH2Cl2) of secondary alcohol mixtures, obtained from the hydride reduction of the precursor ketones (6,YO) to the alkenes, have also been measured. A comparison of this selectivity data for nucleophilic trapping of 4eq‐substituted (X) 2‐adamantyl cations (4, RH and Me) with the corresponding information for 5‐substituted (X) 2‐adamantyl cations (1, RH and Me) has revealed important distinctions between the two series. In particular, whereas extended hyperconjugative effects appear to be the predominant electronic effect governing facial selectivity in the 5,2‐series, electrostatic influences prevail in the 4,2‐disposition. Copyright © 2007 John Wiley & Sons, Ltd.
Polymeric nanocomposites containing polyhedral oligomeric silsesquioxanes prepared via frontal polymerization
Authors: Mariani Alberto , Alzari Valeria , Monticelli Orietta , Pojman John A. , Caria Giuseppe 
Published: August 2007

AbstractFrontal polymerization (FP) has been successfully applied, for the first time, to obtain polymeric nanocomposites containing polyhedral oligomeric silsesquioxanes (POSS) in an amine‐cured epoxy matrix. Variations of maximum temperature (Tmax) and front velocity (Vf) have been studied. A comparison of these products with the corresponding materials, obtained by the classical batch polymerization technique, demonstrated that FP allows a higher degree of conversion than batch polymerization. The products have been characterized in terms of their thermal behavior with DSC analysis. SEM and X‐ray analyses revealed the morphology and the structures of the nanocomposites. The nanocomposites obtained by FP have the same characteristics of those synthesized, in much longer times, by batch polymerization. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4514–4521, 2007
UV‐photodimerization in uracil‐substituted dendrimers for high density data storage
Authors: Lohse Brian , Vestberg Robert , Ivanov Mario T. , Hvilsted Søren , Berg Rolf H. , Ramanujam P. S. , Hawker Craig J. 
Published: August 2007

AbstractTwo series of uracil‐functionalized dendritic macromolecules based on poly (amidoamine) PAMAM and 2,2‐bis(hydroxymethylpropionic acid) bis‐MPA backbones were prepared and their photoinduced (2π+2π) cycloaddition reactions upon exposure to UV light at 257 nm examined. Dendrimers up to 4th generation were synthesized and investigated as potential materials for high capacity optical data storage with their dimerization efficiency compared to uracil as a reference compound. This allows the impact of increasing the generation number of the dendrimers, both the number of chromophores, as well as the different steric environments, on the performance of each series of dendrimers to be investigated. The (uracil)12‐[G‐2]‐bis‐MPA and (uracil)8‐[G‐1]‐PAMAM were observed to have high dimerization efficiency in solution with different behavior being observed for the PAMAM and bis‐MPA dendrimers. The dendrimers with the best dimerization efficiency in solution were then examined in the solid state as thin films cast on quartz plates, and their film qualities along with their photodimerization performance studied. High quality films with a transmission response of up to 70% in 55 s. when irradiated at 257 nm with an intensity of 70 mW/cm2 could be obtained suggesting future use as recording media for optical data storage. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4401–4412, 2007
Ozone Formation in a Coaxial DC Corona Discharge under Carbon Dioxide Gas Flow
Authors: Országh Juraj , Skalný Ján D. , Mason Nigel J. 
Published: August 2007

AbstractOzone formation has been monitored in DC corona discharges fed by pure carbon dioxide in a flowing regime. Ozone concentrations have been measured for both positive and negative polarities of the discharge. Several different electrical parameters of the discharge have been measured. The onset voltage in the positive corona is approximately 1 kV higher than in a similar negative discharge, however, the maximum ozone concentration and total discharge current were found to be higher in the negative corona discharge. The gas flow rate is shown to influence the CV characteristics within a negative corona but, in contrast, only a marginal effect of flow rate was observed in positive corona. The mobility of both negative and positive charge carriers in the drift region of the discharges have been derived from CV characteristics.
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Hazard assessment of potential periglacial debris flows based on GIS‐based spatial modelling and geophysical field surveys: a case study in the Swiss Alps
Authors: Kneisel C. , Rothenbühler C. , Keller F. , Haeberli W. 
Published: August 2007

AbstractCombined geomorphological and geophysical approaches were used to perform a hazard assessment of potential periglacial debris flow. Possible debris flow initiation zones were identified within a GIS‐based model and located based on geomorphic attributes which contribute the most to this type of instability. In permafrost‐affected alpine environments, these include the extent and location of ground ice and permafrost. In a potential debris flow‐starting zone in the Upper Engadine (moraine/debris rock glacier complex Boval) two‐dimensional electrical resistivity surveys were used to detect the presence/absence of permafrost and to estimate active‐layer depth. The results show that the moraine complex represents a periglacial debris reservoir which consists of frozen and unfrozen debris. The ice‐bonded part of the moraine is largely protected from sudden destabilisation and retrogressive erosion can be assumed to be limited. However, future degradation or loss of permafrost in the lower parts of the debris rock glacier would increase the amount of erodible debris and generally reduce mechanical stability. Copyright © 2007 John Wiley & Sons, Ltd.