bluuebunny/crossref_metadata_2025 huggingface dataset:
Are Oxazolidinones Really Unproductive, Parasitic Species in Proline Catalysis? – Thoughts and Experiments Pointing to an Alternative View
Authors: Seebach Dieter , Beck Albert K. , Badine D. Michael , Limbach Michael , Eschenmoser Albert , Treasurywala Adi M. , Hobi Reinhard , Prikoszovich Walter , Linder Bernard
Published: March 2007

The N,O‐acetal and N,O‐ketal derivatives (oxazolidinones) formed from proline, and aldehydes or ketones are well‐known today, and they are detectable in reaction mixtures involving proline catalysis, where they have been considered ‘parasitic dead ends’. We disclose results of experiments performed in the early 1970's, and we describe more recent findings about the isolation, characterization, and reactions of the oxazolidinone derived from proline and cyclohexanone. This oxazolidinone reacts (THF, room temperature) with the electrophiles β‐nitrostyrene and chloral (=trichloroacetaldehyde), to give the Michael and aldol adduct, respectively, after aqueous workup (Scheme 5). The reactions occur even at −75° when catalyzed with bases such as 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) or EtN(i‐Pr)2 (DIPEA) (10%; Table 1). It is shown by NMR (Figs. 1 and 3) and IR analysis (Figs. 2 and 4) that the primarily detectable product (before hydrolysis) of the reaction with the nitro‐olefin is again an oxazolidinone. When dissolved in hydroxylic solvents such as MeOH, ‘hexafluoroisopropanol’ ((CF3)2CHOH; HFIP), AcOH, CF3COOH, or in LiBr‐saturated THF, the ring of the oxazolidinone from cyclohexanone and proline opens up to the corresponding iminium ion (Tables 2–4), and when treated with strong bases such as DBU (in (D8)THF) the enamino‐carboxylate derived from proline and cyclohexanone is formed (Scheme 8). Thus, the two hitherto putative participants (iminium ion and enamine) of the catalytic cycle (Scheme 9) have been characterized for the first time. The commonly accepted mechanism of the stereoselective C,C‐ or C,X‐bond‐forming step (i.e., A–D) of this cycle is discussed and challenged by thoughts about an alternative model with a pivotal role of oxazolidinones in the regio‐ and diastereoselective formation of the intermediate enamino acid (by elimination) and in the subsequent reaction with an electrophile (by trans‐addition with lactonization; Schemes 11–14). The stereochemical bias between endo‐ and exo‐space of the bicyclo[3.3.0]octane‐type oxazolidinone structure (Figs. 5 and 6) is considered to possibly be decisive for the stereochemical course of events. Finally, the remarkable consistency, with which the diastereotopic Re‐face of the double bond of pyrrolidino‐enamines (derived from proline) is attacked by electrophiles (Schemes 1 and 15), and the likewise consistent reversal to the Si‐face with bulky (Aryl)2C‐substituents on the pyrrolidine ring (Scheme 16) are discussed by invoking stereoelectronic assistance from the lone pair of pyramidalized enamine N‐atoms.
The Stereostructure of Porphyra‐334: An Experimental and Calculational NMR Investigation. Evidence for an Efficient ‘Proton Sponge’
Authors: Klisch Manfred , Richter Peter , Puchta Ralph , Häder Donat‐P. , Bauer Walter
Published: March 2007

The mycosporine‐like amino acid (MAA) porphyra‐334 (1) is subjected to extensive 1H‐ and 13C‐NMR analysis as well as to density‐functional‐theory (DFT) calculations. All 1H‐ and 13C‐NMR signals of 1 are assigned, as well as the resonances of prochiral proton pairs. This is achieved by 500‐MHz standard COSY, HMQC, and HMBC experiments, as well as by one‐dimensional (DPFGSE‐NOE) and two‐dimensional (NOESY) NOE experiments. Diffusion measurements (DOSY) confirm that 1 is monomeric in D2O solution. DFT Calculations yield 13C‐NMR chemical shifts which are in good agreement for species 6 which is the imino N‐protonated form of 1. An exceptionally high proton affinity of 265.7 kcal/mol is calculated for 1, indicating that 1 may behave as a very powerful ‘proton sponge’ of comparable strength as synthetic systems studied so far. Predictions of 13C‐NMR chemical shifts by the ‘NMRPredict’ software are in agreement with the DFT data. The absolute configuration at the ring stereogenic center of 1 is concluded to be (S) from NOE data as well as from similarities with the absolute configuration (S) found in mycosporine‐glycine 16. This supports the assumption that 1 is biochemically derived from 3,3‐O‐didehydroquinic acid (17). The data obtained question the results recently published by a different research group claiming that the configuration at the imino moiety of 1 is (Z), rather than (E) as established by the here presented study.
5‐Morpholino‐1,2,3,4‐thiatriazole as a Sulfur‐Transfer Reagent in the Reactions with Thioketones
Authors: Mlostoń Grzegorz , Woźnicka Marta , Heimgartner Heinz
Published: March 2007

The thermal decomposition of 5‐morpholino‐1,2,3,4‐thiatriazole (7), which leads to the extrusion of an active form of sulfur, in the presence of different thioketones is described. The interception of the S‐atom by the CS bond leads to in situ formation of an elusive thiocarbonyl S‐sulfide of type 5. This intermediate is a prone 1,3‐dipole, which undergoes effectively [2+3] cycloadditions with thioketones to yield 1,2,4‐trithiolane derivatives in a regioselective manner. Unexpectedly, 3,3‐dichloro‐2,2,4,4‐tetramethyl‐3‐thioxocyclobutanone (1c) does not lead to the expected symmetrical 1,2,4‐trithiolane. This result can be explained by the reduced stability of the corresponding thiosulfine 5c. Three‐component reactions, which were carried out in the presence of equimolar amounts of two different thioketones, result in the formation of ‘mixed’ 1,2,4‐trithiolanes of type 8.
At‐a‐station hydraulic geometry relations, 1: theoretical development
Authors: Singh Vijay P. , Zhang L.
Published: March 2007

This paper, the first of two, hypothesizes that: (1) the temporal variation of stream power of a river channel at a given station with varying discharge is accomplished by the temporal variation in channel form (flow depth and channel width) and hydraulic variables, including energy slope, flow velocity and friction; (2) the change in stream power is distributed among the changes in flow depth, channel width, flow velocity, slope, and friction, depending on the boundary conditions that the channels has to satisfy. The second hypothesis is a result of the principle of maximum entropy and the theory of minimum energy dissipation or its simplified minimum stream power. These two hypotheses lead to families of at‐a‐station hydraulic geometry relations. The conditions under which these families of relations can occur in the field are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Investigating hydrologic connectivity and its association with threshold change in runoff response in a temperate forested watershed
Authors: James April L. , Roulet Nigel T.
Published: March 2007

Hydrological studies across varied climatic and physiographic regions have observed small changes in the ‘states of wetness’; based on average soil moisture, can lead to dramatic changes in the amount of water delivered to the stream channel. This non‐linear behaviour of the storm response has been attributed to a critical switching in spatial organization of shallow soil moisture and hydrologic connectivity. However, much of the analysis of the role of soil moisture organization and connectivity has been performed in small rangeland catchments. Therefore, we examined the relationship between hydrologic connectivity and runoff response within a temperate forested watershed of moderate relief. We have undertaken spatial surveys of shallow soil moisture over a sequence of storms with varying antecedent moisture conditions. We analyse each survey for evidence of hydrologic connectivity and we monitor the storm response from the catchment outlet. Our results show evidence of a non‐linear response in runoff generation over small changes in measures of antecedent moisture conditions; yet, unlike the previous studies of rangeland catchments, in this forested landscape we do not observe a significant change in geostatistical hydrologic connectivity with variations in antecedent moisture conditions. These results suggest that a priori spatial patterns in shallow soil moisture in forested terrains may not always be a good predictor of critical hydrologic connectivity that leads to threshold change in runoff generation, as has been the case in rangeland catchments. Copyright © 2007 John Wiley & Sons, Ltd.
C620R mutation of the murine ret proto‐oncogene: Loss of function effect in homozygotes and possible gain of function effect in heterozygotes
Authors: Yin Luo , Puliti Aldamaria , Bonora Elena , Evangelisti Cecilia , Conti Valerio , Tong Wei‐Min , Medard Jean‐Jacques , Lavoué Marie‐France , Forey Nathalie , Wang Lily C. , Manié Serge , Morel Gérard , Raccurt Mireille , Wang Zhao‐Qi , Romeo Giovanni
Published: March 2007

Germline RET mutations are responsible for different inherited disorders: Hirschsprung disease (congenital aganglionic megacolon), caused by loss of function mutations, familial medullary thyroid carcinoma and multiple endocrine neoplasia type 2, caused by gain of function mutations. Intriguingly, some RET mutations, including C620R, are associated with both types of diseases. To investigate the dual role of such RET mutations, a mouse model with a targeted mutation retC620R was generated. retC620R/C620R offspring die during the first postnatal day, and show kidney agenesis and intestinal aganglionosis. Decreased outgrowth of the Ret‐positive cells was observed in retC620R/C620R neuronal cell cultures, which is suggestive of an impaired migration, proliferation or survival of the Ret‐expressing cells. Electronmicroscopy revealed the absence of membrane‐bound Ret in retC620R/C620R cells as compared to ret+/+ and ret+/C620R cells. On the other hand, aged ret+/C620R mice develop precancerous lesions in the adrenal gland or in the thyroid. Our results suggest that the retC620R mutation has a loss of function effect in homozygotes and exhibits a dominant gain of function effect with low penetrance causing hyperplasia in heterozygotes. © 2007 Wiley‐Liss, Inc.
Absence of measles virus genome and transcripts in Hodgkin‐Reed/Sternberg cells of a cohort of Hodgkin lymphoma patients
Authors: Maggio Ewerton , Benharroch Daniel , Gopas Jacob , Dittmer Ulf , Hansmann Martin‐Leo , Küppers Ralf
Published: March 2007

In the search for viruses in Hodgkin lymphoma (HL), it was reported that the measles virus (MV) can be detected in the Hodgkin‐Reed/Sternberg (HRS) cells of a large fraction of cases from Israel by immunohistochemistry or in situ hybridisation, suggesting a potential role of this virus in HL. To extend and validate this report, we studied HL‐derived cell lines and HRS cells microdissected from German and Israeli HL cases for the presence of MV RNA genome and transcripts, analysing three MV genes (nucleoprotein, matrix, haemaglutinin). A cell line infected with MV was used as a positive control for MV RNA detection. MV RNA was detectable down to 1 infected cell in a nested RT‐PCR. Pools of microdissected HRS cells from 18 German and 7 Israeli classical HL (the latter reported to be positive for MV proteins in the previous study) were analysed for MV genome and transcripts. None of the viral genes was obtained in independent replicate experiments in any of the 25 HL cases. A Southern blot hybridisation performed with the second round PCR products further confirmed the negative results. Whole HL tissue sections were analysed to exclude MV in non‐HRS cells, also yielding negative results. We also analysed four HL cell lines and showed that these are MV‐negative, too. In this cohort of German and Israeli HL patients—including cases previously typed as MV‐positive—and HL‐derived cell lines, there was no evidence of MV genome in the HRS cells. © 2007 Wiley‐Liss, Inc.
Medical radiation exposure and breast cancer risk: Findings from the Breast Cancer Family Registry
Authors: John Esther M. , Phipps Amanda I. , Knight Julia A. , Milne Roger L. , Dite Gillian S. , Hopper John L. , Andrulis Irene L. , Southey Melissa , Giles Graham G. , West Dee W. , Whittemore Alice S.
Published: March 2007

Moderate to high‐dose radiotherapy is known to increase the risk of breast cancer. Uncertainties remain about the effects of low‐dose chest X‐rays, particularly in individuals at increased genetic risk. We analyzed case‐control data from the Breast Cancer Family Registry. Self‐reported data on therapeutic and diagnostic radiation exposures to the chest were available for 2,254 breast cancer cases and 3,431 controls (1,556 unaffected sisters and 1,875 unrelated population controls). We used unconditional logistic regression analyses to estimate odds ratios (OR) and 95% confidence intervals (CI) associated with radiation exposure, after adjusting for age, study center, country of birth, and education. Increased risks for breast cancer were found for women who had radiotherapy for a previous cancer (OR = 3.55, CI = 1.47–8.54) and diagnostic chest X‐rays for tuberculosis (OR = 2.49, CI = 1.82–3.40) or pneumonia (OR = 2.19, CI = 1.38–3.47). Risks were highest for women with a large number of exposures at a young age or exposed in earlier calendar years. There was no evidence of increased risk associated with other diagnostic chest X‐rays (not including tuberculosis or pneumonia), both in women with and without indicators of increased genetic risk (i.e., diagnosed at age <40 years or family history of breast cancer). Given the widespread and increasing use of medical diagnostic radiation, continued surveillance of breast cancer risk is warranted, particularly in women at specific genetic risk, such as those carrying mutations in BRCA1 or BRCA2. © 2007 Wiley‐Liss, Inc.
Cutaneous malignant melanoma in children and adolescents in Sweden, 1993–2002: The increasing trend is broken
Authors: Karlsson Pia M. , Fredrikson Mats
Published: March 2007

The incidence of cutaneous malignant melanoma rose rapidly in teenagers in Sweden during 1973–1992, while it remained low in younger children. To study the further trends and characteristics of melanoma in this young population, data on all cases in individuals under 20 years of age reported to the Swedish Cancer Registry during 1993–2002, and the corresponding pathology reports were examined. Seventy‐nine cases were reported to the Registry. There were 24 males and 55 females. Most melanomas occurred on the trunk followed by the legs in both genders. The median tumor thickness was 0.8 mm. Children under age 15 had thicker melanomas than individuals aged 15–19. Superficial spreading melanoma was the most common histological subtype (43/78, 55%). The melanoma‐specific 5‐year survival rate was 90%. During 1993–2002, the age‐standardized incidence fell to 3.6/million from 5.0/million in 1983–1992 (RR 0.74, 95% CI 0.58–0.92). The most pronounced decrease was for melanomas on the trunk in boys and on the legs in girls. The incidence for 15–19‐year‐old boys peaked for the cohort born between 1968 and 1972 and for girls between 1973 and 1977. The decrease in incidence may be a result of public health campaigns aiming at reducing sun exposure in childhood. A contributing effect from an increased immigration of individuals with darker complexions and at a lower melanoma risk is probable. © 2007 Wiley‐Liss, Inc.
Serum C‐peptide, IGFBP‐1 and IGFBP‐2 and risk of colon and rectal cancers in the European Prospective Investigation into Cancer and Nutrition
Authors: Jenab Mazda , Riboli Elio , Cleveland Rebecca J. , Norat Teresa , Rinaldi Sabina , Nieters Alexandra , Biessy Carine , Tjønneland Ann , Olsen Anja , Overvad Kim , Grønbæk Henning , Clavel‐Chapelon Françoise , Boutron‐Ruault Marie‐Christine , Linseisen Jakob , Boeing Heiner , Pischon Tobias , Trichopoulos Dimitrios , Oikonomou Eleni , Trichopoulou Antonia , Panico Salvatore , Vineis Paolo , Berrino Franco , Tumino Rosario , Masala Giovanna , Peters Petra H. , van Gils Carla H. , Bueno‐de‐Mesquita H. Bas , Ocké Marga C. , Lund Eiliv , Mendez Michelle A. , Tormo María José , Barricarte Aurelio , Martínez‐García Carmen , Dorronsoro Miren , Quirós José Ramón , Hallmans Göran , Palmqvist Richard , Berglund Göran , Manjer Jonas , Key Timothy , Allen Naomi E. , Bingham Sheila , Khaw Kay‐Tee , Cust Anne , Kaaks Rudolf
Published: March 2007

Western style diets and lifestyles are associated with increasing rates of obesity, diabetes and insulin resistance. Higher circulating insulin levels may modulate cell proliferation and apoptosis either directly or indirectly by increasing the bioactivity of IGF‐I and decreasing the bioactivity of some of its binding proteins. The objective of this study was to determine the association of increasing levels of serum C‐peptide, a biomarker of pancreatic insulin secretion, and IGF binding proteins (IGFBP) ‐1 and ‐2 with colorectal cancer risk in a case–control study nested within the European Prospective Investigation into Cancer and Nutrition (EPIC), a large cohort involving 10 Western European countries. A total of 1,078 colorectal cancer cases were matched (age, date of blood donation, fasting status, gender, study center) to an equal number of control subjects. Relative cancer risks were estimated using conditional logistic regression models. Serum C‐peptide concentration was positively associated with an increased colorectal cancer risk for the highest versus the lowest quintile (OR = 1.56, 95% CI = 1.16–2.09, ptrend < 0.01), which was slightly attenuated after adjustment for BMI and physical activity (OR = 1.37, 95% CI = 1.00–1.88, ptrend = 0.10). When stratified by anatomical site, the cancer risk was stronger in the colon (OR = 1.67, 95% CI = 1.14–2.46, ptrend < 0.01) than in the rectum (OR = 1.42, 95% CI = 0.90–2.25, ptrend = 0.35). The cancer risk estimates were not heterogeneous by gender or fasting status. No clear colorectal cancer risk associations were observed for IGFBP‐1 or ‐2. This large prospective study confirms that hyperinsulinemia, as determined by C‐peptide levels, is associated with an increased colorectal cancer risk. © 2007 Wiley‐Liss, Inc.
New paths to dramatically improve your planning and control processes
Authors: Player Steve
Published: March 2007

The Beyond Budgeting framework is a new approach for organizational planning and control. Depending on the people and the culture, an organization can take either a revolutionary or an evolutionary approach to implementation. Three common traits required by a move to continuous planning and adaptive controls are: (1) a degree of enlightened leadership that allows innovation; (2) commitment to change culture and behaviors as well as processes; and (3) utilization of fast, open information systems. The organizations taking these approaches are better prepared to create lean, ethical, and adaptive organizations. © 2007 Wiley Periodicals, Inc.
Global acquisitions: A seller's market?
Authors: Benet Bruce A. , Goldberg Stephen R.
Published: March 2007

Global acquisitions have rebounded recently. But what factors were responsible? Has it become a seller's market? And what does the future hold? © 2007 Wiley Periodicals, Inc.
Reversal of BCRP‐mediated multidrug resistance by stable expression of small interfering RNAs
Authors: Lv Hui , He Zhimin , Liu Xiaorong , Yuan Jianhui , Yu Yanhui , Chen Zhuchu
Published: March 2007

Breast cancer resistance protein (BCRP) is an ATP‐binding cassette multidrug transporter that confers resistance to various anticancer drugs like Mitoxantrone. Overexpression of BCRP confers multidrug resistance (MDR) in cancer cells and is a frequent impediment to successful chemotherapy. For stable reversal of BCRP‐depending MDR by RNA interference technology, a hU6‐RNA gene promoter‐driven expression vector encoding anti‐BCRP short hairpin RNA (shRNA) molecules was constructed. By treating endogenously and exogenously expresses high levels of BCRP cells with these constructs, expression of the targeted BCRP‐encoding mRNA, and transport protein was inhibited completely. Furthermore, the accumulation of mitoxantrone in the anti‐BCRP shRNA‐treated cells increased. And the sensitivity to mitoxantrone of anti‐BCRP shRNA‐treated cells is increased 14.6‐fold and 2.44‐fold respectively compared to their control (P < 0.05). These data indicated that stable shRNA‐mediated RNAi could be tremendously effective in reversing BCRP‐mediated MDR and showed promises in overcoming MDR by gene therapeutic applications. J. Cell. Biochem. 102: 75–81, 2007. © 2007 Wiley‐Liss, Inc.
Raman analysis of underglaze pigments on porcelain art
Authors: de Waal D.
Published: March 2007

A Raman analysis of the cobalt blue underglaze pigment on intact Ming porcelain plates from the Hongzhi (1488–1505) and Wanli (1573–1620) periods is presented. Copyright © 2007 John Wiley & Sons, Ltd.
Influence of fatty acid composition on the tribological performance of two vegetable‐based lubricants
Authors: Siniawski Matthew T. , Saniei Nader , Adhikari Bigyan , Doezema Lambert A.
Published: March 2007

In light of diminishing natural resources, global climatic change and increased environmental sensitivity, renewable‐based lubricants are being considered potential alternatives to petroleum‐based lubricants. Understanding the tribological performance of vegetable‐based lubricants in relation to their chemical composition is essential for their industrial implementation. This study focuses on the friction and abrasion rate characteristics of soybean and sunflower oils in comparison to a base mineral oil under sliding wear at ambient conditions for various applied loads. It was found that the abrasion rate and friction were the least severe for the soybean, followed by the sunflower oil. The observed trends were attributed to differences in their fatty acid compositions, in particular, a lower percentage of linoleic and oleic acids within the soybean oil. Copyright © 2007 John Wiley & Sons, Ltd.
Isolation and structural determination of sorbinols A and B, new triterpenes from Sorbus cashmariana, by 1D and 2D NMR spectroscopy
Authors: Kazmi Mehdi Hassan , Ahmed Ejaz , Hameed Saira , Malik Abdul , Ashraf Muhammad
Published: March 2007

Two new pentacyclic triterpenes, sorbinols A (1) and B (2) have been isolated from the ethyl acetate fraction of Sorbus cashmariana and their structures assigned from 1H and 13C NMR spectra, DEPT and by 2D COSY, NOE, HMQC and HMBC experiments. Both 1 and 2 showed moderate inhibitory potential against the enzyme lipoxygenase. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis and spectroscopic characterisation of a combinatorial library based on the fungal natural product 3‐chloro‐4‐hydroxyphenylacetamide
Authors: Davis Rohan A. , Pierens Gregory K. , Parsons Peter G.
Published: March 2007

Parallel solution‐phase chemistry has yielded a series of secondary amide analogues of the fungal natural product 3‐chloro‐4‐hydroxyphenylacetamide. 3‐Chloro‐4‐hydroxyphenylacetic acid was coupled to a variety of primary amines using 1‐ethyl‐3‐(3′‐dimethylamino‐ propyl)‐carbodiimide hydrochloride. The desired products were obtained in good yield and high purity following rapid silica purification. All analogues were spectroscopically characterised using NMR, UV, IR and MS data. One compound displayed moderate cytotoxicity against the human melanoma and prostate cell lines, MM96L and DU145. Copyright © 2007 John Wiley & Sons, Ltd.
Differences in perceived barriers to volunteering to formal organizations: Lack of time versus lack of interest
Authors: Sundeen Richard A. , Raskoff Sally A. , Garcia M. Cristina
Published: March 2007

This article reports the findings of a study of perceived barriers to volunteering to formal organizations by nonvolunteers. We examine the types of barriers, their frequencies, and their relationships with individual‐level sociodemographic characteristics of nonvolunteers. Data from a 2001–2002 national survey conducted by the U.S. Bureau of Labor Statistics are analyzed using multiple regression techniques. Contrary to general expectations, only three barriers—lack of time, lack of interest, and ill health—are fairly common. Furthermore, as expected, different social class groups identify different types of barriers. The article concludes with a discussion of the theoretical implications of the findings (for example, how indicators of social and cultural capital affect access to volunteer opportunities) and practical implications concerning recruitment of volunteers.
The power of relationships
Authors: Til Jon Van
Published: March 2007

The Deliberative Democracy Handbook: Strategies for Effective Civic Engagement in the 21st Century, edited by John Gastil and Peter Levine. San Francisco: Jossey‐Bass, 2005. 336 pp., $36.00 cloth.

Politics Is About Relationship: A Blueprint for the Citizens' Century, by Harold H. Saunders. New York: Palgrave Macmillan, 2005. 242 pp., $35.00 cloth.

Going Public: An Organizer's Guide to Citizen Action, by Michael Gecan. New York: Anchor, 2002. 224 pp., $12.00 paper.

The Civic Renewal Movement: Community‐Building and Democracy in the United States, by Carmen Sirianni and Lewis A. Friedland. Dayton, Ohio: Kettering Foundation Press, 2005. 260 pp., $9.95 paper.
Application of the theory of colloid stability to the problem of particle formation in aqueous solutions of vinyl acetate
Authors: Dunn A. S. , Chong L. C.‐H.
Published: March 2007

The problem of particle formation in aqueous solutions of vinyl acetate is treated according to the Deryaguin‐Landau‐Verwey‐Overbeek (D.L.V.O.) theory of the stability of lyophobic colloids.

In the absence of surfactants, polymer particles are stabilised by ionic end‐groups derived from persulphate initiator. Palit's dye partition method is used to determine the number of these end‐groups and the amount of adsorbed sodium dodecyl sulphate which was used as emulsifying agent in some experiments; this enables the electrical forces of repulsion between particles to be calculated. The Hamaker constant which defines the magnitude of the van der Waals' forces of attraction between particles has been estimated for polyvinyl acetate. The dependence of the stability of the polymer dispersion formed on the concentrations of initiator, emulsifier, etc. is investigated; the observations accord with expectations on the basis of D.L.V.O. theory. It is shown that small particles are unstable with respect to coalescence with larger particles. The processes of polymerisation and particle growth are essentially independent in this system.
Effect of hostile environments on adhesive joints III. Role of simple alcohols with unstressed epoxide adhesive
Authors: Kerr C. , Macdonald N. C. , Orman S.
Published: March 2007

Exposure of aluminium‐epoxide bonds to methanol, ethanol, ammonia and formamide has shown that the hydrogen bonding ability of the ‘solvent’ plays little part in determining the effect on bond strength. The strength of the bonds may be increased by short‐term exposures to the alcohols. A mechanism is proposed to explain the data.
Characterisation of latex particles produced by emulsion polymerisation
Authors: Hearn J. , Ottewill R. H. , Shaw J. N.
Published: March 2007

The emulsion polymerisation of styrene, using sodium dodecanoate as emulsifier and hydrogen peroxide as initiator, has been used to prepare a series of polystyrene latices of different sizes. The size range covered was from 600 Å to 4230 Å. After removal of the soap by dialysis, the surface groups on the particles were characterised by electrophoresis. The main surface groupings were found to be carboxyl groups. Number‐average molecular weight determinations were carried out using osmometry and it was found that the molecular weight decreased as the particle size increased. The evidence obtained suggests that the growth of a latex particle involves a surface‐phase polymerisation.
Inferences on the mechanism of emulsion polymerisation of styrene from characterisation of the polymer end‐groups
Authors: van den Hul H. J. , Vanderhoff J. W.
Published: March 2007

Solute electrolyte and adsorbed emulsifier can be removed by ion exchange from polystyrene latices prepared with persulphate initiator. Rigorous purification of the ion‐exchange resins is necessary to avoid contamination by leached polyelectrolytes. These ion‐exchanged latices are stabilised by strong acid surface groups ‐ sulphate end‐groups of the polymer molecules. The number of surface groups as determined by conductometric titration of the latex, plus the number buried within the particle as determined by conductometric titration of the polymer in solution (or by X‐ray fluorescence), is less than the expected value of two per polymer molecule. The other end‐groups are shown to be hydroxyl groups by oxidation to the carboxyl form followed by ion exchange and titration. The total number of end‐groups thus determined is close to two per molecule. As the pH of the polymerisation medium is decreased, the proportion of hydroxyl end‐groups increases and that of the sulphate end‐groups decreases. No carboxyl groups are detected in ion‐exchanged latices prepared in a nitrogen atmosphere, independent of the nature of the emulsifier. The dye partition method gives end‐group concentrations that are far lower than those determined by titration or X‐ray fluorescence, probably because the formation of the dye end‐group ion‐pair is not complete. Finally, for latices prepared at relatively low emulsifier concentrations, the contribution of the sulphate end‐groups to the surface charge density is significant and cannot be overlooked, as has been done in the past.
Effect of an elastomeric phase on the properties of rigid thermoplastics
Authors: Haward R. N.
Published: March 2007

Present knowledge of the properties of glassy thermoplastics in the solid state is briefly reviewed. Crazing and deformation processes are discussed together with their influence on the toughness of polymers. Toughness can be enhanced by introducing rubber, the properties of the reinforced polymer depending not only on the rubber involved but also on the matrix. It is shown that polyolefins, e.g. polyethylene and polypropylene, can be considered as rubber‐reinforced plastics. The effect of introducing rubber in the form of block copolymers is briefly considered.
Perfluoroalkylene‐linked aromatic polymers
Authors: Critchley J. P. , McLoughlin V. C. R. , Thrower J. , White I. M.
Published: March 2007

Polymers of the type (m‐C6H4·(CF2)m·m‐C6H4‐X))n have been synthesised and their properties are reported. They include polyesters and polycarbonates, polysiloxanes, polyimides and poly‐(1,3‐phenylenehexafluoro‐trimethylene. Preparation of the precursors was facilitated by the discovery of a direct fluoroalkylation process involving fluoroalkylcopper intermediates. In various instances, the effects of introducing m‐phenylene‐perfluoroalkylene units on the properties of these polymers, particularly their glass transition temperatures, are compared with the corresponding effects from m‐phenylene ether units.
Some new concepts in polymer stabilisation
Authors: Scott G.
Published: March 2007

The mechanisms of antioxidant activity are briefly reviewed. Antioxidant systems based on catalaseactive compounds, and the use of sulphur‐containing metal complexes and transition metal ions as antioxidants are discussed.
Spiking neurons, dopamine, and plasticity: Timing is everything, but concentration also matters
Authors: Thivierge Jean‐Philippe , Rivest François , Monchi Oury
Published: March 2007

While both dopamine (DA) fluctuations and spike‐timing‐dependent plasticity (STDP) are known to influence long‐term corticostriatal plasticity, little attention has been devoted to the interaction between these two fundamental mechanisms. Here, a theoretical framework is proposed to account for experimental results specifying the role of presynaptic activation, postsynaptic activation, and concentrations of extracellular DA in synaptic plasticity. Our starting point was an explicitly‐implemented multiplicative rule linking STDP to Michaelis‐Menton equations that models the dynamics of extracellular DA fluctuations. This rule captures a wide range of results on conditions leading to long‐term potentiation and depression in simulations that manipulate the frequency of induced corticostriatal stimulation and DA release. A well‐documented biphasic function relating DA concentrations to synaptic plasticity emerges naturally from simulations involving a multiplicative rule linking DA and neural activity. This biphasic function is found consistently across different neural coding schemes employed (voltage‐based vs. spike‐based models). By comparison, an additive rule fails to capture these results. The proposed framework is the first to generate testable predictions on the dual influence of DA concentrations and STDP on long‐term plasticity, suggesting a way in which the biphasic influence of DA concentrations can modulate the direction and magnitude of change induced by STDP, and raising the possibility that DA concentrations may inverse the LTP/LTD components of the STDP rule. Synapse 61:375‐390, 2007. © 2007 Wiley‐Liss, Inc.
Amyloid β‐peptide Aβ1–42 but not Aβ1–40 attenuates synaptic AMPA receptor function
Authors: Parameshwaran Kodeeswaran , Sims Catrina , Kanju Patrick , Vaithianathan Thirumalini , Shonesy Brian C. , Dhanasekaran Muralikrishnan , Bahr Ben A. , Suppiramaniam Vishnu
Published: March 2007

The brains of Alzheimer's disease (AD) patients have large numbers of plaques that contain amyloid beta (Aβ) peptides which are believed to play a pivotal role in AD pathology. Several lines of evidence have established the inhibitory role of Aβ peptides on hippocampal memory encoding, a process that relies heavily on α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) receptor function. In this study the modulatory effects of the two major Aβ peptides, Aβ1–40 and Aβ1–42, on synaptic AMPA receptor function was investigated utilizing the whole cell patch clamp technique and analyses of single channel properties of synaptic AMPA receptors. Bath application of Aβ1–42 but not Aβ1–40 reduced both the amplitude and frequency of AMPA receptor mediated excitatory postsynaptic currents in hippocampal CA1 pyramidal neurons by ∼60% and ∼45%, respectively, in hippocampal CA1 pyramidal neurons. Furthermore, experiments with single synaptic AMPA receptors reconstituted in artificial lipid bilayers showed that Aβ1–42 reduced the channel open probability by ∼42% and channel open time by ∼65% and increased the close times by several fold. Aβ1–40, however, did not show such inhibitory effects on single channel properties. Application of the reverse sequence peptide Aβ42–1 also did not alter the mEPSC or single channel properties. These results suggest that Aβ1–42 but not Aβ1–40 closely interacts with and exhibits inhibitory effects on synaptic AMPA receptors and may contribute to the memory impairment observed in AD. Synapse 61:367‐374, 2007. © 2007 Wiley‐Liss, Inc.
Legacies of the past in the present‐day forest biodiversity: a review of past land‐use effects on forest plant species composition and diversity
Authors: Hermy Martin , Verheyen Kris
Published: March 2007

Particularly in the temperate climate zone many forests have, at some moment in their history, been used as agriculture land. Forest cover is therefore often not as stable as it might look. How forest plant communities recovered after agriculture was abandoned allows us to explore some universal questions on how dispersal and environment limit plant species abundance and distribution. All studies looking at the effects of historical land use rely on adequate land use reconstruction. A variety of tools from maps, archival studies, and interviews to field evidence and soil analyses contribute to that. They allow us to distinguish ancient from recent forests and many studies found pronounced differences in forest plant species composition between them. A considerable percentage of our forest flora is associated with ancient forests. These ancient forest plant species (AFS) all have a low colonization capacity, suggesting that dispersal in space (distance related) and time (seed bank related) limit their distribution and abundance. However recent forests generally are suitable for the recruitment of AFS. There is clear evidence that dispersal limitation is more important than recruitment limitation in the distribution of AFS. Dispersal in time, through persistent seed banks, does not play a significant role. Ancient forests are not necessary more species‐rich than recent forest, but if diversity is limited to typical forest plant species then ancient forests do have the highest number of plant species, making them highly important for nature conservation. The use of molecular markers, integrated approaches and modelling are all part of the way forward in this field of historical ecology.
The price of novels in the late Qing Dynasty
Authors: Dakang CHEN
Published: March 2007

The introduction of advanced printing technology from the West and “the fiction revolution” accelerated fiction writing and printing into the modern mode. The book markets quickly expanded and the proportion of fiction publications solidly grew, which all led to a fiercer competition for the reading market. During this transition, the price of fictional literature fluctuated and was stabilized only through the fierce competition as well as the supervision from the mass media.
n‐3 Polyunsaturated Fatty Acids and Atopy in Korean Preschoolers
Authors: Hwang Inkyung , Cha Aeri , Lee Hyosun , Yoon Hyejung , Yoon Taeho , Cho Byungmann , Lee Suill , Park Yongsoon
Published: March 2007

Atopy is a growing problem for Korean children. Since eicosapentaenoic acid is a precursor of less active inflammatory eicosanoids, n‐3 polyunsaturated fatty acids (PUFA) may have a protective effect on atopy. This study was undertaken to determine whether n‐3 PUFA in red blood cells (RBC) is lower in atopic than in non‐atopic preschoolers. Three hundred and eight Korean children aged 4–6 years were enrolled. Total RBC fatty acid composition was measured by gas chromatography. The prevalence of atopic dermatitis, allergic rhinitis, or asthma was 29%. Total RBC n‐3 PUFA were lower in preschoolers with atopy than controls (9.8 ± 1.2 vs. 11.4 ± 1.6%; P < 0.05), while n‐6 PUFA (33.0 ± 1.4 vs. 32.2 ± 1.0%; P < 0.05) and n‐6/n‐3 PUFA ratio (3.4 ± 0.6 vs. 2.8 ± 0.5; P < 0.05) were greater. The following factors were also associated with an increase in atopy: higher saturated fatty acids (39.6 ± 1.4 vs. 40.6 ± 1.9; P < 0.05) and arachidonic acid (15.3 ± 1.6 vs. 16.0 ± 2.9; P < 0.05), and lower total PUFA (43.8 ± 0.7 vs. 42.8 ± 1.4; P < 0.05) and omega‐3 index (EPA + DHA; 9.1 ± 0.8 vs. 7.8 ± 0.5; P < 0.05) in RBC. Maternal history of atopy was a significant (P < 0.05) risk factor, while lactation was not. The results suggest that a reduced content of n‐3 PUFA in the RBC membrane could play a role in early children atopy.
The influence of maternal treadmill running during pregnancy on short‐term memory and hippocampal cell survival in rat pups
Authors: Kim Hong , Lee Sang‐Hak , Kim Sung‐Soo , Yoo Jae‐Hyun , Kim Chang‐Ju
Published: March 2007

Maternal exercise during pregnancy has been suggested to exert the beneficial effects on the brain functions of offspring. In the present study, we attempted to determine the effects of maternal treadmill running during pregnancy on short‐term memory ability, hippocampal cell survival, and the expression of brain‐derived neurotrophic factor (BDNF) mRNA in rat pups. After confirming pregnancy, the pregnant rats were divided into two groups: the control group and the running group (n = 6 in each group). Beginning on the 15th day of pregnancy, the pregnant rats in the running group were forced to run on a treadmill for 30 min at a mild‐intensity, once a day until delivery. After all the pregnant rats had given birth, there were rat pups available for use in this study in each group (n = 15 in each group). The latency of the step‐down avoidance task was used in order to evaluate the short‐term memory ability of the rat pups on the 28 days after birth. Immunohistochemistry for 5‐bromo‐2′‐deoxyuridine (BrdU) and reverse transcription‐polymerase chain reaction (RT‐PCR) for BDNF mRNA were performed to determine hippocampal neurogenesis and hippocampal BDNF mRNA expression of the rat pups on the 29 days after birth, respectively. Our results revealed that maternal running during pregnancy resulted in significant increase in the expression of BDNF mRNA, enhanced hippocampal cell survival, and improved the short‐term memory capability of rat pups, as compared to those measured in the control group. The findings of our study provide evidence that maternal running during gestational period may enhance the brain functions of offspring.
Body fat and fat-free mass inter-relationships: Forbes's theory revisited
Authors: Hall Kevin D.
Published: March 2007

A theoretical equation was developed by Forbes that quantifies the fat-free proportion of a weight change as a function of the initial body fat. However, Forbes's equation was strictly valid only for infinitesimal weight changes. Here, I extended Forbes's equation to account for the magnitude and direction of macroscopic body weight changes. The new equation was also re-expressed in terms of an alternative representation of body composition change defined by an energy partitioning parameter called the P-ratio. The predictions of the resulting equations compared favourably with data from human underfeeding and overfeeding experiments and accounted for previously unexplained trends in the data. The magnitude of the body weight change had a relatively weak effect on the predicted body composition changes and the results were very similar to Forbes's original equation for modest weight changes. However, for large weight changes, such as the massive weight losses found in patients following bariatric surgery, Forbes's original equation consistently underestimated the fat-free mass loss, as expected. The new equation that accounts for the magnitude of the weight loss provides better predictions of body composition changes in such patients.
La question de la liberté d'expression dans les
démêlés judiciaires et les revers administratifs de
CHOI-FM
Authors: Gingras Anne-Marie
Published: March 2007

Résumé. Cet article porte sur
l'utilisation du concept de “ liberté d'expression
” par une station de radio de Québec, CHOI-FM, dans ses
démêlés avec le CRTC et dans le procès de
Sophie Chiasson contre la station en Cour supérieure du
Québec. Bien que les promoteurs de CHOI-FM aient fait de la
liberté d'expression leur argument principal en 2004 et 2005,
nous défendons l'hypothèse que cet argument
était purement instrumental. Cependant, le concept de
liberté d'expression mérite d'être
analysé, car il a un pouvoir d'évocation peu commun en
démocratie; il renvoie en effet à la nécessaire
effervescence du débat public et à l'individualisme.
D'autre part, la liberté d'expression a aussi
été associée au populisme et au discours illicite,
éléments auxquels elle confère un vernis de
respectabilité.

Abstract. This paper deals with the use of the concept of
freedom of expression by a Quebec City radio station, CHOI-FM, in its
dispute with the CRTC and in the court case of Sophie Chiasson before the
Quebec Cour supérieure. Although freedom of expression is
the main argument used by CHOI-FM in 2004 and 2005, our hypothesis is that
this argument is mainly instrumental. Nevertheless, freedom of expression
must be analyzed because it is a major symbol of democracy; it is linked
with lively public debate and individualism. In this case, freedom of
expression is also used in an attempt to lend respectability to populism
and illicit discourse.
Problems and Methods in the Study of Politics
Authors: Loewen Peter John
Published: March 2007

Problems and Methods in the Study of Politics, Ian Shapiro,
Rogers M. Smith and Tarek E. Masoud, eds., Cambridge: Cambridge University
Press, 2004, pp. xi., 419.

This important volume recounts a meeting of some the best minds in
political science, but, in the end, it is a meeting in the physical sense
(as the volume comes out of a conference held at Yale in 2002) and not
really in any intellectual sense. The ostensible goal of the volume is to
proffer answers to what the editors call “a fundamental question
about the proper place of problems and methods in the study of
politics…. Which should political scientists chose first, a problem
or a method?” (1). Unfortunately, a good many of the contributors to
the volume ask whether this is a question at all. Perhaps unsurprisingly,
most of those who reject the question do not have objections to the
increased technical and mathematical nature of modern political science.
And, equally unsurprising, those who suggest that method has too often
come before problem are those who have earlier, and often eloquently,
bemoaned the rise of rational choice theory and econometric applications.
As an intellectual rapprochement, the work fails. It rather resembles a
dinner of extended family, where long-held differences and grievances are
kept just under the breath, but as a collection of essays by leading
scholars which consider the methodologies and epistemologies of political
science, the volume is a smashing success.
The Essential Thomas Jefferson
Authors: Newman Stephen L.
Published: March 2007

The Essential Thomas Jefferson, Jean M. Yarbrough, ed.,
Indianapolis and Cambridge: Hackett Publishing Company, Inc., 2006, pp.
xxxvii, 287.

This is a useful collection of Jefferson's political writings
well suited to undergraduate and graduate courses in political theory and
especially in American political thought. There are twelve public papers
and addresses (including “A Summary View of the Rights of British
America” and, of course, the Declaration of Independence, excerpts
from the “Notes on Virginia,” and 44 letters to various
correspondents. This compares favourably with an older and larger
anthology edited by the distinguished Jefferson scholar Merrill Peterson
(The Portable Thomas Jefferson, New York: Viking, 1975), which
features roughly the same number of public papers and addresses but also
contains the “Notes on Virginia” in its entirety and some 75
letters. While the Peterson volume is more inclusive, Yarbrough's
decision to excerpt the “Notes” is understandable, given how
few chapters bear directly on political questions, and the selected
correspondence provides an ample survey of Jefferson's views on a
variety of topics.
Collective Dreams: Political Imagination and Community
Authors: Mooers Colin
Published: March 2007

Collective Dreams: Political Imagination and Community,
Keally D. McBride, University Park PA: Penn State University Press, 2005,
pp. 157.

Political imagination is greatly underrated, not least because there
is so little of it in what passes for “official” politics
these days. But it is also understudied by political theorists whose
domain encompasses the many imagined but rarely realized versions of the
“good society” handed down from the past. And yet political
imagination is arguably central to every vision of an alternative
political order. Plato never lived in his Republic; Hobbes never wandered
through the state of nature; and Marx never knew the rule of the
“associated producers.” But, all of them may have felt that
they had glimpsed elements of these alternate futures in their own time.
Hobbes, after all, lived through the English Revolution which he may have
thought resembled a “war of all against all” and Marx
witnessed the heady days of the Paris Commune. This is surely as true
today. Social conservatives may espy the glimmerings of a heavenly utopia
in their local church group. Progressive social activists may see a new
social order prefigured in their food co-op or trade union. Political
imagination, in other words, is just as much a part of the world we
inhabit as it is of those we dream of inhabiting. However, as Keally
McBride observes, “Imagination itself, as opposed to its products,
is generally not studied in political science. But it is our best tool for
changing the world” (1).