bluuebunny/crossref_metadata_2025 huggingface dataset:
Familial orofaciodigital syndrome type I revealed by ultrasound prenatal diagnosis of porencephaly
Authors: Thauvin‐Robinet Christel , Rousseau Thierry , Durand Christine , Laurent Nicole , Maingueneau Catherine , Faivre Laurence , Sagot Paul , Nivelon‐Chevallier Annie
Published: September 2002

Porencephaly is a rare central nervous system (CNS) abnormality that can be caused by an intraparenchymal destructive process or a developmental defect. Here we report on a prenatal ultrasound diagnosis of complex CNS abnormalities including agenesis of the corpus callosum, agenesis of the cerebellar vermis, bilateral hydrocephaly, and bilateral porencephaly in fetus at 33 weeks' gestation. The diagnosis of familial orofaciodigital syndrome type I (OFD I) was raised after fetal autopsy, clinical examination of the family, and the X‐linked dominant inheritance pattern. This is the fourth report of porencephaly in association with OFD I. We discuss the difficulties in genetic counselling since OFD I shows variable expressivity of the phenotypic features. Furthermore, we emphasize the importance of a detailed ultrasound examination after a prenatal diagnosis of porencephaly. Copyright © 2001 John Wiley & Sons, Ltd.
Between pregnancy biological variability of first trimester markers of Down syndrome: implications for screening in subsequent pregnancies
Authors: Spencer Kevin
Published: September 2002

In a group of 149 women who had undergone routine first trimester screening using fetal nuchal translucency thickness (NT) and maternal serum free β‐hCG and pregnancy associated plasma protein‐A (PAPP‐A) in two consecutive pregnancies the within person between pregnancy biological variability of these markers has been assessed. For fetal NT there was no correlation between NT MoM in the first and second pregnancy (r=0.0800). For maternal serum free β‐hCG MoM a significant correlation was observed (r=0.4174) as was also found for PAPP‐A MoM (r=0.3270). The implications for such between pregnancy marker association is that women who have an increased risk of Down syndrome in their first pregnancy are 1.5–2 times more likely to repeat this event in their next pregnancy. This observation may be useful in counselling women in the first trimester screening of a subsequent pregnancy. Copyright © 2001 John Wiley & Sons, Ltd.
A survey of diabetes management in nursing homes: the need for whole systems of care
Authors: Douek Isabelle F. , Bowman Clive , Croxson Simon
Published: September 2002

A structured questionnaire survey of nurse managers of the 40 nursing homes in the catchment of a district hospital revealed inconsistencies in diabetes care and unsafe capillary blood testing practice. Seven homes had diabetes management policies; in the 33 homes that did not, management was based on information received at admission being incorporated into the care plan. Regarding the management of ill insulin‐dependent residents, nine homes stated that insulin should be withheld although all homes indicated that they would increase the frequency of blood glucose monitoring and seek advice. 18/40 homes had a policy for the management of a hypoglycaemic episode; those without a policy relied on the knowledge of the trained staff present. Sharing of blood sampling equipment within homes, a risk to infection control, was identified as commonplace. A lack of guidance appeared a major cause of inconsistency in patterns of ongoing care for residents with diabetes. Specific guidelines and training are required to assure diabetes care and clinical governance in care homes. Copyright © 2001 John Wiley & Sons, Ltd.
Self‐monitoring of blood glucose; frequency, determinants and self‐adjustment of treatment in an adult Swedish diabetic population
Authors: Hjelm Katarina , Nyberg Per , Apelqvist Jan
Published: September 2002

Objective

To analyse the utilisation of self‐monitoring of blood glucose (SMBG) among adult diabetic subjects.

Methods

A cross‐sectional study with a standardized interview, a physical examination, and an evaluation of medical records comprising all known diabetic subjects living in six defined primary health care districts in southern Sweden. Of 1861 identified subjects aged >25 years, 90.1% participated. Mean age was 66±0.4 yrs; 94% were diagnosed ≥30 yrs, and 70.4% were not gainfully employed.

Results

SMBG was used by 36.3% of all subjects (20.5% regularly, 15.8% sporadically). In 51.8% of cases regularly performing SMBG the results were used for self‐adjustment of treatment (SAT). In multiple logistic regression analysis SMBG was related to awareness of illness (OR [95% CI]; 2.64[1.59–4.40]), treatment with insulin (2.52 [1.92–3.29]), and inversely related to age (50–69 yrs; 0.70[0.50–0.99], >70 yrs; 0.40[0.28–0.59]). The strongest independent influence on SAT based on SMBG results was awareness of illness (3.42[1.74–6.74]), followed by duration >10 yrs (1.74[1.28–2.38]), and there was an inverse relation to a multiple disease pattern in terms of cardiocerebrovascular disease and age. Living conditions, social position, or treatment location were not evidently related to SMBG or SAT.

Conclusions

A large proportion of adult individuals does not use SMBG regularly. Regular SMBG performers do not use it for SAT, and thus the use is not optimized for achieving good glycaemic control and especially with regard to awareness of illness. Copyright © 2001 John Wiley & Sons, Ltd.
Electron‐ and X‐ray‐induced electron emissions from insulators
Authors: Cazaux Jacques
Published: September 2002

The electron emission yields of insulators irradiated with ultra‐short pulsed X‐ray and electron beams differ significantly from those of metals. The main experimental results are reviewed and it is shown that the use of simple models for the transport and for the escape of the generated secondary electrons accounts for the role of the temperature and of the crystalline state on these yields (besides the role of the chemical composition of the insulator of interest).

When permanent irradiation is used, charging and damaging effects occur and correlated mechanisms are then considered. The present analysis concerns a wide variety of insulators (from oxides and halides to polymers) investigated with a wide variety of techniques (XPS, AES, SEM, etc.) and various practical consequences are also deduced.

© 2001 Society of Chemical Industry
Characterization of non‐conducting materials: a promise of quality and productivity improvements in various industrial fields
Authors: Gressus C Le
Published: September 2002

An increase in reliability and a decrease in production cost of systems that include insulators require a better knowledge of the origins of friction, wear, adhesion, fracture and electric breakdown. By doing this, for example, a manufacturer could adapt his fabrication to the user's operational conditions whereas, at present, he only can offer a catalogue of standard specified products.

The macroscopic behaviour of a material depends on the defects therein; these in turn determine the electric charge distribution and the internal energy of the material. Seen in this light, many pioneering results can be understood and used to clarify the experiments required for validating new theories of breakdown or wear.

Several laboratories have worked together to demonstrate the direct relationships that exist between the microscopic parameters of charge and energy localization or relaxation and macroscopic behaviour. One essential point was to find how to carry out experiments whilst preserving the material's intrinsic defect state during sample preparation and how to characterize defects related to stresses applied to the material. Another point was to investigate the phenomena that occur at the early stage of wear, fracture and breakdown before catastrophic failure. Therefore the use of time‐ and spatially‐resolved measurements has been essential.

This work reviews some pioneering results, pointing out the importance of polarization and conduction on apparently different behaviour (wear, adhesion and breakdown). These results have been explained from classical solid state physics and electrostatics backgrounds. When the experiments were carried out, however, characterization techniques for interpretating the results were missing, so that they did not receive the attention they deserved. Surprisingly, and as discussed in the second part, because these new characterization techniques have not been sufficiently disseminated in industry, these pioneering results and theories have not been practically applied. As a consequence, standard insulator specifications still do not reflect our actual knowledge. In the third part, some examples illustrate technological progress that can be made by combining some new characterization techniques with the standard ones.

© 2001 Society of Chemical Industry
Succinoylation of wheat straw hemicelluloses in N,N‐dimethylformamide/lithium chloride systems
Authors: Sun Runcang , Sun X F , Zhang F Y
Published: September 2002

The chemical modification of native wheat straw hemicelluloses with succinic anhydride using N,N‐dimethylformamide/lithium chloride system as solvent and pyridine and/or 4‐dimethyaminopyridine as catalyst has been examined. In particular, the progress of the succinoylation reaction is studied as a function of the molar ratio of succinic anhydride/anhydroxylose unit in native hemicelluloses from 1:1 to 5:1, DMAP concentration 0.025–0.20 g, reaction temperature 40–140 °C, and reaction time 2–12 h with succinic anhydride. The degree of substitution of succinylated hemicelluloses ranges between 0.4 and 1.5 depending on the experimental conditions. FTIR and 1H NMR spectroscopic characterization of the esterified polymers indicates a monoester substitution. The thermal stability of the esterified polymer decreases slightly upon chemical modification, but no significant further decrease in thermal stability is observed for DS ≥ 0.7.

© 2001 Society of Chemical Industry
Lead–yeast hexokinase interaction: modifications to protein structure caused by the metal
Authors: Teijón C , Olmo R , Socorro J M , Blanco M D , Romero A , Teijón J M
Published: September 2002

The interaction between lead and yeast hexokinase has been studied. Lead provokes a large variation in the aggregation state of the protein, forming bigger structures of high molecular mass. This phenomenon is characterized by a small modification in the tridimensional structure and a great variation in the secondary structure. There is a loss in α‐helix which is compensated by an enhancement in β‐sheet. The polypeptide chain is more stable in the β‐sheet structure corresponding to the aggregate forms. During this change the enzyme maintains a high level of activity in the monomer and also in the aggregate form. This implies that the enzyme function is not greatly affected by the change, and active sites are retained without important modifications. According to kinetic measurements the ATP site is more affected than the glucose site. There is a mixed type inhibition with a main competitive component when glucose acts as a variable substrate.

© 2001 Society of Chemical Industry
Characteristics of bifacial solar cells under bifacial illumination with various intensity levels
Authors: Ohtsuka H. , Sakamoto M. , Koyama M. , Tsutsui K. , Uematsu T. , Yazawa Y.
Published: September 2002

The characteristics of bifacial solar cells with different rear structures were investigated under front, rear and bifacial illumination with an intensity of 0.4–4.2 suns. Five kinds of solar cells, rear flat local‐BSF cells, rear textured local‐BSF cells (textured RLB cells), rear total‐BSF cells, rear floating‐emitter cells, and triode cells with double‐sided junctions, were tested. The I–V characteristics of the cells under bifacial illumination were measured with a newly designed measurement system that simultaneously illuminated both surfaces of the cells. In the short‐circuit current (JSC) and the saturation current evaluations, the bifacial illumination effect, which means that the power output of the cell is intrinsically improved by adding rear illumination, was not observed. Although the RLB cells showed a nonlinear increase inJSCand enhancedVOC, these increases did not make a practical contribution to extra output because of the low levels of these characteristics. When we evaluated the maximum output power, the bifacial illumination effect was only observed in the triode cell. A triode cell can decrease resistive loss by introducing light from both surfaces, compared with a conventional cell with one junction. Copyright © 2001 John Wiley & Sons, Ltd.
Manufacturing tolerances of terrestrial concentrator p‐on‐n GaAs solar cells
Authors: Algora Carlos , Díaz Vicente
Published: September 2002

The increasing interest in the manufacturing of terrestrial concentrator GaAs solar cells calls for the need to establish the guidelines, assessments and tolerances of the production process. Accordingly, this paper analyses, for the first time, the tolerances of this process. The influence of the entire solar cell (antireflecting coatings, semiconductor structure and series resistance) is considered. More specifically, the parameters analysed are: the thickness of the double antireflecting coating, window thickness, emitter thickness, base thickness, emitter doping level, base doping level, shadowing factor and specific front contact resistance. The results are presented in the form of iso‐efficiency plots as a function of the aforementioned parameters. Therefore, besides the conclusions extracted in this paper, numerous others may be formed according to particular necessities. Copyright © 2001 John Wiley & Sons, Ltd.
Limiting efficiency for current‐constrained two‐terminal tandem cell stacks
Authors: Brown Andrew S. , Green Martin A.
Published: September 2002

Tandem stacks of solar cells have clearly shown their ability to increase the efficiency of solar energy conversion. In the past, the challenge in making these devices often has been in the materials science area, working around the constraints imposed by different materials to meet requirements imposed by lattice constant and bandgap. However, developments in the field of low‐dimensional structures; particularly superlattices, may allow generic approaches to developing tandem stacks of large numbers of cells. The current flowing through such devices will have to be constrained so that it is the same through all the cells within the stack since separately contacting such large numbers of cells is impractical. The series‐constrained two‐terminal tandem solar cell is compared with the unconstrained tandem solar cell for stacks containing both small and large numbers of cells. As expected, we find that the detailed balance limiting efficiencies for the two‐terminal cell are less than those for the unconstrained device involving the same number of cells, due to the constraint imposed by current matching. However the difference is always less than 1.5% relative under the design spectrum. However, the two‐terminal case shows much greater variation in efficiency if the spectrum varies from that for which the design was optimised. A relationship is derived between the performance of a two‐terminal stack of a finite number of cells and the performance of an unconstrained stack of an infinite number of cells. This shows that the performance of the two‐terminal device approaches that of the unconstrained device as the number of cells in the stack approaches infinity. Copyright © 2002 John Wiley & Sons, Ltd.
Ideal efficiency of monolithic, series‐connected multijunction solar cells
Authors: Tobías I. , Luque A.
Published: September 2002

Two‐terminal, monolithic tandem solar cells represent the most interesting implementation of tThe multijunction photovoltaic array capable of very high efficiency. Radiative coupling among the cells, and between the cells and the substrate, along with series interconnection are features present in this approach. Their effect on efficiency is quantified for arrays with a small number of cells in the radiative limit and compared with the best experimental cells to assess their potential improvement. Finally, it is shown that they do not lower the limiting efficiency of the infinite tandem array, which is determined by the emission losses through the illuminated face. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis, characterization, and electrical properties of nanostructural polyaniline doped with novel sulfonic acids (4‐{n‐[4‐(4‐nitrophenylazo)phenyloxy]alkyl}aminobenzene sulfonic acid)
Authors: Qiu Hongjin , Wan Meixiang
Published: September 2002

4‐{n‐[4‐(4‐Nitrophenylazo)phenyloxy]alkyl}aminobenzene sulfonic acid (Cn‐ABSA, where n = 2, 4, 6, 8, or 10) as a novel dopant for conducting polymers of polyaniline (PANI) was designed and synthesized. The molecular structure of Cn‐ABSA was characterized with 1H NMR, Fourier transform infrared, and secondary‐ion mass spectrometry. Nanostructures (nanotubes or nanorods) of PANI–(Cn‐ABSA) were successfully synthesized with a self‐assembly process in the presence of Cn‐ABSA as the dopant. The morphology (shape and size) and conductivity of the resulting nanostructures strongly depended on the number of alkyl groups (n) and, in particular, the addition of water before polymerization. The formed micelles of aniline/Cn‐ABSA/water were proposed to be templatelike in forming PANI–(Cn‐ABSA) nanostructures on the basis of the emulsion properties measured by dynamic light scattering. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3485–3497, 2001
Graft copolymers from star‐shaped and hyperbranched polystyrene macromonomers
Authors: Al‐Muallem Hasan A. , Knauss Daniel M.
Published: September 2002

Branched polystyrene macromonomers were synthesized by the slow addition of a stoichiometric amount of either 4‐(chlorodimethylsilyl)styrene or vinylbenzyl chloride as a coupling agent to living polystyryllithium. Star‐shaped macromonomers were produced by the addition of the coupling agent alone, and hyperbranched macromonomers resulted from the addition of the coupling agent along with styrene monomer. Star and hyperbranched graft copolymers were produced by the copolymerization of the macromonomers with styrene and methyl methacrylate. The copolymers were characterized by gel permeation chromatography coupled with multi‐angle laser light scattering, 1H NMR spectroscopy, and Soxhlet extraction to determine that the macromonomers were incorporated in high yields into the copolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3547–3555, 2001
Viscosity effects in cobaloxime‐mediated catalytic chain‐transfer polymerization of methacrylates
Authors: Roberts G. Evan , Davis Thomas P. , Heuts Johan P. A. , Russell Gregory T.
Published: September 2002

The effect of bulk viscosity on the cobaloxime‐mediated catalytic chain‐transfer polymerization of methacrylates at 60 °C was investigated by both the addition of high molecular weight poly(methyl methacrylate) to methyl methacrylate polymerization and the dilution of benzyl methacrylate polymerization by toluene. The results indicate that the bulk viscosity is not directly linked to the chain‐transfer activity. The previously measured relationship between chain‐transfer‐rate coefficient and monomer viscosity therefore probably reflects changes at the molecular level. However, the results in this article do not necessarily disprove a diffusion‐controlled reaction rate because cobaloxime diffusion is expected to scale with the monomer friction coefficient rather than bulk viscosity. Considering the published data, to date we are not able to distinguish between a diffusion‐controlled reaction rate or a mechanism directly affected by the methacrylate substituent. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 782–792, 2002; DOI 10.1002/pola.10152
Discovery of dendrimers and dendritic polymers: A brief historical perspective*
Authors: Tomalia Donald A. , Fréchet Jean M. J.
Published: September 2002

A brief historical perspective relating the discovery of dendrimers and other dendritic polymers is presented. Dendritic polymers are recognized as the fourth major class of macromolecular architecture consisting of four sub‐ classes, namely, (1) random hyperbranched, (2) dendrigrafts, (3) dendrons, and (4) dendrimers. The previous literature is reviewed with anecdotal events leading to implications for dendrimers in the emerging science of nanotechnology. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2719–2728, 2002
Polyolefin graft copolymers via living polymerization techniques: Preparation of poly(n‐butyl acrylate)‐graft‐polyethylene through the combination of Pd‐mediated living olefin polymerization and atom transfer radical polymerization
Authors: Hong Sung Chul , Jia Shijun , Teodorescu Mircea , Kowalewski Tomasz , Matyjaszewski Krzysztof , Gottfried Amy C. , Brookhart Maurice
Published: September 2002

Poly(n‐butyl acrylate)‐graft‐branched polyethylene was successfully prepared by the combination of two living polymerization techniques. First, a branched polyethylene macromonomer with a methacrylate‐functionalized end group was prepared by Pd‐mediated living olefin polymerization. The macromonomer was then copolymerized with n‐butyl acrylate by atom transfer radical polymerization. Gel permeation chromatography traces of the graft copolymers showed narrow molecular weight distributions indicative of a controlled reaction. At low macromonomer concentrations corresponding to low viscosities, the reactivity ratios of the macromonomer to n‐butyl acrylate were similar to those for methyl methacrylate to n‐butyl acrylate. However, the increased viscosity of the reaction solution resulting from increased macromonomer concentrations caused a lowering of the apparent reactivity ratio of the macromonomer to n‐butyl acrylate, indicating an incompatibility between nonpolar polyethylene segments and a polar poly(n‐butyl acrylate) backbone. The incompatibility was more pronounced in the solid state, exhibiting cylindrical nanoscale morphology as a result of microphase separation, as observed by atomic force microscopy. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2736–2749, 2002
Synthesis and characterization of novel soluble triphenylamine‐containing aromatic polyamides based on N,N′‐bis(4‐aminophenyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine
Authors: Liou Guey‐Sheng , Hsiao Sheng‐Huei , Ishida Mina , Kakimoto Masaaki , Imai Yoshio
Published: September 2002

A new triphenylamine‐containing aromatic diamine, N, N′‐bis(4‐aminophenyl)‐N, N′‐diphenyl‐1,4‐phenylenediamine, was prepared by the condensation of N,N′‐diphenyl‐1,4‐phenylenediamine with 4‐fluoronitrobenzene, followed by catalytic reduction. A series of novel aromatic polyamides with triphenylamine units were prepared from the diamine and various aromatic dicarboxylic acids or their diacid chlorides via the direct phosphorylation polycondensation or low‐temperature solution polycondensation. All the polyamides were amorphous and readily soluble in many organic solvents such as N, N‐dimethylacetamide and N‐methyl‐2‐pyrrolidone. These polymers could be solution cast into transparent, tough, and flexible films with good mechanical properties. They had useful levels of thermal stability associated with relatively high glass‐transition temperatures (257–287 °C), 10% weight‐loss temperatures in excess of 550 °C, and char yields at 800 °C in nitrogen higher than 72%. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2810–2818, 2002
Linear functionalized polyethylene prepared with highly active neutral Ni(II) complexes
Authors: Connor Eric F. , Younkin Todd R. , Henderson Jason I. , Hwang Sonjong , Grubbs Robert H. , Roberts William P. , Litzau Johnathan J.
Published: September 2002

Neutral Ni(II) salicylaldimine catalysts (pendant ligand = NCMe or PPh3) were used to copolymerize ethylene with monomers containing esters, alcohols, anhydrides, and amides and yielded linear functionalized polyethylene in a single step. α‐Olefins and polycyclic olefin comonomers carrying functionality were directly incorporated into the polyethylene backbone by the catalysts without any cocatalyst, catalyst initiator, or other disturber compounds. The degree of comonomer incorporation was related to the monomer structure: tricyclononenes > norbornenes > α‐olefins. A wide range of comonomer incorporation, up to 30 mol %, was achieved while a linear polyethylene structure was maintained under mild conditions (40 °C, 100 psi ethylene). Results from the characterization of the copolymers by solution and solid‐state NMR techniques, thermal analysis, and molecular weight demonstrated that the materials contained a relatively pure microstructure for a functionalized polyethylene that was prepared in one step with no catalyst additive. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2842–2854, 2002
Acid chloride‐functionalized hyperbranched polyester for facile and quantitative chain‐end modification: One‐pot synthesis and structure characterization
Authors: Yamaguchi Nori , Wang Jin‐Shan , Hewitt J. Michael , Lenhart William C. , Mourey Thomas H.
Published: September 2002

Carboxylic acid chloride end‐functionalized all‐aromatic hyperbranched polyesters were prepared from the bulk polycondensation of the AB2 monomer 5‐(trimethylsiloxy)isophthaloyl dichloride. The acid chloride end functionality of the hyperbranched polyester was modified in situ with methanol and yielded methyl ester ends in a one‐pot process. Chain‐end functionalization and esterification were quantitative according to both potentiometric titration and 1H NMR analysis. The signals of 1H and 13C NMR spectra of the esterified hyperbranched polyester were fully assigned from model compounds of the focal, linear, dendritic, and terminal units. The degree of branching and molecular weight averages measured by 1H and 13C NMR spectroscopy and multidetector size exclusion chromatography increased systematically with increasing polymerization temperatures between 80 and 200 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2855–2867, 2002
Transesterification reaction of the BaSO4‐filled PBT/poly(ethylene terephthalate) blend
Authors: Lee Sang‐Soo , Kim Junkyung , Park Min , Lim Soonho , Choe Chul Rim
Published: September 2002

For the poly(butylene terephthalate) (PBT)/poly(ethylene terephthalate) blend system, the addition of a barium sulfate (BaSO4) particle, the surface of which was modified with a titanate coupling agent, suppressed the transesterification reaction. The polyester chain ends, considered one of the main sites of transesterification reactions, were blocked through a chemical reaction with the surface hydroxyl groups of the BaSO4 particle; a block copolymer‐like architecture was obtained with a BaSO4 linkage. The formation of the block copolymer‐like structure for the polyesters stuck to the BaSO4 particle facilitated crystallization by providing a crystallization nucleus without a significant transesterification reaction, resulting in higher mechanical properties. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2589–2597, 2001
Melt rheology of polypropylene containing small amounts of high molecular weight chain. I. Shear flow
Authors: Sugimoto M. , Masubuchi Y. , Takimoto J. , Koyama K.
Published: September 2002

Large enhancements of the melt strength of polypropylene (PP) were achieved by the introduction of high molecular weight polyethylene (PE) into PP. The viscoelastic properties of the high‐melt‐strength PP melts under shear flow were investigated. It was found that the rheological properties of the high‐melt‐strength PP were distinctly different from those of conventional PP. The elastic response at low frequencies was significantly enhanced in comparison with the conventional PP, implying a presence of a long relaxation time mode that was not revealed in conventional PP. In step‐shear measurements, the fast and slow relaxation processes that characterized the linear viscoelastic properties were observed also for nonlinear relaxation moduli. The dependence of the damping for the slow process of the high‐melt‐strength PP on shear strain was much weaker than that of the fast process. These rheological behaviors characterizing the long relaxation time mode were further enhanced with the increasing concentration of high molecular mass PE. The unusual shear rheological behaviors were discussed in view of the role of high molecular weight PE as a long relaxation time mode within PP. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2692–2704, 2001
Scattering properties of a single semiflexible polyelectrolyte
Authors: Ghosh K. , Muthukumar M.
Published: September 2002

The structure factor of a single semiflexible polyelectrolyte has been calculated as a function of chain length, intrinsic backbone stiffness, and salt concentration. Because of the insignificant coupling of the intrinsic stiffness and electrostatic persistence length, we carry out our calculations in the flexible limit. Within the variational scheme adopted here, we obtain fractal dimensions consistent with our earlier calculations of the configurational properties. As the chain length is increased, the electrostatic interaction is progressively screened, leading to the crossover regions. In the first crossover, the effective fractal dimension, Deff, is as low as 1, and in the second crossover Deff is 5/3, although the radius of gyration exponent is 2/5. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2644–2652, 2001
Sub‐glass‐transition temperature interface formation between an immiscible glass rubber pair
Authors: Forrest J. A. , Dalnoki‐Veress K.
Published: September 2002

We used neutron reflectivity to measure the interfacial width in the immiscible system polystyrene/poly(n‐butyl methacrylate) (PS/PnBMA). Measurements were made on the same samples at temperatures ranging from below the glass‐transition temperature (Tg) of PS to slightly above. We observed significant broadening of the interface at temperatures below the Tg of PS, indicating chain mobility below the bulk Tg value. The interfacial width exhibited a plateau at a value of 20 Å in the temperature range of 365 K < T < 377 K. A control experiment involving hydrogenated and deuterated PS films (hPS/dPS) showed no such broadening over the same temperature region. The results are consistent with a reduction of the Tg of PS in the interfacial region of ∼20 K. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2664–2670, 2001
Why protein R‐factors are so large: A self‐consistent analysis
Authors: Vitkup Dennis , Ringe Dagmar , Karplus Martin , Petsko Gregory A.
Published: September 2002

The R‐factor and R‐free are commonly used to measure the quality of protein models obtained in X‐ray crystallography. Well‐refined protein structures usually have R‐factors in the range of 20–25%, whereas intrinsic errors in the experimental data are usually around 5%. We use molecular dynamics simulations to perform a self‐consistent analysis by which we determine the major factors contributing to large values of protein R‐factors. The analysis shows that significant R‐factor values can arise from the use of isotropic B‐factors to model anisotropic protein motions and from coordinate errors. Even in the absence of coordinate errors, the use of isotropic B‐factors can cause the R‐factors to be around 10%; for coordinate errors smaller than 0.2 Å, the two errors types make similar contributions. The inaccuracy of the energy function used and multistate protein dynamics are unlikely to make significant contributions to the large R‐factors. Proteins 2002;46:345–354. © 2002 Wiley‐Liss, Inc.
Classification of the caspase–hemoglobinase fold: Detection of new families and implications for the origin of the eukaryotic separins
Authors: Aravind L. , Koonin Eugene V.
Published: September 2002

A comprehensive sequence and structural comparative analysis of the caspase–hemoglobinase protein fold resulted in the delineation of the minimal structural core of the protease domain and the identification of numerous, previously undetected members, including a new protease family typified by the HetF protein from the cyanobacterium Nostoc. The first bacterial homologs of legumains and hemoglobinases were also identified. Most proteins containing this fold are known or predicted to be active proteases, but multiple, independent inactivations were noticed in nearly all lineages. Together with the tendency of caspase‐related proteases to form intramolecular or intermolecular dimers, this suggests a widespread regulatory role for the inactive forms. A classification of the caspase–hemoglobinase fold was developed to reflect the inferred evolutionary relationships between the constituent protein families. Proteins containing this domain were so far detected almost exclusively in bacteria and eukaryotes. This analysis indicates that caspase–hemoglobinase‐fold proteases and their inactivated derivatives are widespread in diverse bacteria, particularly those with a complex development, such as Streptomyces, Anabaena, Mesorhizobium, and Myxococcus. The eukaryotic separin family was shown to be most closely related to the mainly prokaryotic HetF family. The phyletic patterns and evolutionary relationships between these proteins suggest that they probably were acquired by eukaryotes from bacteria during the primary, promitochondrial endosymbiosis. A similar scenario, supported by phylogenetic analysis, seems to apply to metacaspases and paracaspases, with the latter, perhaps, being acquired in an independent horizontal transfer to the eukaryotes. The acquisition of the caspase–hemoglobinase‐fold domains by eukaryotes might have been critical in the evolution of important eukaryotic processes, such as mitosis and programmed cell death. Proteins 2002;46:355–367. © 2002 Wiley‐Liss, Inc.
Interactions of Streptomyces griseus aminopeptidase with amino acid reaction products and their implications toward a catalytic mechanism
Authors: Gilboa R. , Spungin‐Bialik A. , Wohlfahrt G. , Schomburg D. , Blumberg S. , Shoham G.
Published: September 2002

Streptomyces griseus aminopeptidase (SGAP) is a double‐zinc exopeptidase with a high preference toward large hydrophobic amino‐terminus residues. It is a monomer of a relatively low molecular weight (30 kDa), it is heat stable, it displays a high and efficient catalytic turnover, and its activity is modulated by calcium ions. The small size, high activity, and heat stability make SGAP a very attractive enzyme for various biotechnological applications, among which is the processing of recombinant DNA proteins and fusion protein products. Several free amino acids, such as phenylalanine, leucine, and methionine, were found to act as weak inhibitors of SGAP and hence were chosen for structural studies. These inhibitors can potentially be regarded as product analogs because one of the products obtained in a normal enzymatic reaction is the cleaved amino terminal amino acid of the substrate. The current study includes the X‐ray crystallographic analysis of the SGAP complexes with methionine (1.53 Å resolution), leucine (1.70 Å resolution), and phenylalanine (1.80 Å resolution). These three high‐resolution structures have been used to fully characterize the SGAP active site and to identify some of the functional groups of the enzyme that are involved in enzyme‐substrate and enzyme‐product interactions. A unique binding site for the terminal amine group of the substrate (including the side chains of Glu131 and Asp160, as well as the carbonyl group of Arg202) is indicated to play an important role in the binding and orientation of both the substrate and the product of the catalytic reaction. These studies also suggest that Glu131 and Tyr246 are directly involved in the catalytic mechanism of the enzyme. Both of these residues seem to be important for substrate binding and orientation, as well as the stabilization of the tetrahedral transition state of the enzyme‐substrate complex. Glu131 is specifically suggested to function as a general base during catalysis by promoting the nucleophilic attack of the zinc‐bound water/hydroxide on the substrate carbonyl carbon. The structures of the three SGAP complexes are compared with recent structures of three related aminopeptidases: Aeromonas proteolytica aminopeptidase (AAP), leucine aminopeptidase (LAP), and methionine aminopeptidase (MAP) and their complexes with corresponding inhibitors and analogs. These structural results have been used for the simulation of several species along the reaction coordinate and for the suggestion of a general scheme for the proteolytic reaction catalyzed by SGAP. Proteins 2001;44:490–504. © 2001 Wiley‐Liss, Inc.
Automated assignment of SCOP and CATH protein structure classifications from FSSP scores
Authors: Getz Gad , Vendruscolo Michele , Sachs David , Domany Eytan
Published: September 2002

We present an automated procedure to assign CATH and SCOP classifications to proteins whose FSSP score is available. CATH classification is assigned down to the topology level, and SCOP classification is assigned to the fold level. Because the FSSP database is updated weekly, this method makes it possible to update also CATH and SCOP with the same frequency. Our predictions have a nearly perfect success rate when ambiguous cases are discarded. These ambiguous cases are intrinsic in any protein structure classification that relies on structural information alone. Hence, we introduce the “twilight zone for structure classification.” We further suggest that to resolve these ambiguous cases, other criteria of classification, based also on information about sequence and function, must be used. Proteins 2002;46:405–415. © 2002 Wiley‐Liss, Inc.
Recombinant baculoviruses for insect control
Authors: Inceoglu Ahmet B , Kamita Shizuo G , Hinton Andrew C , Huang Qihong , Severson Tonya F , Kang Kyung‐don , Hammock Bruce D
Published: September 2002

Baculoviruses are double‐stranded DNA viruses which are highly selective for several insect groups. They are valuable natural control agents, but their utility in many agricultural applications has been limited by their slow speed of kill and narrow host specificity. Baculoviruses have been genetically modified to express foreign genes under powerful promoters in order to accelerate their speed of kill. In our and other laboratories, the expression of genes coding for insect juvenile hormone esterases and various peptide neurotoxins has resulted in recombinant baculoviruses with promise as biological insecticides. These viruses are efficacious in the laboratory, greenhouse and field and dramatically reduce damage caused by insect feeding. The recombinant viruses synergize and are synergized by classical pesticides such as pyrethroids. Since they are highly selective for pest insects, they can be used without disrupting biological control. Because the recombinant virus produces fewer progeny in infected larvae than the wild‐type virus, they are rapidly out‐competed in the ecosystem. The viruses can be used effectively with crops expressing endotoxins of Bacillus thuringiensis. They can be produced industrially but also by village industries, indicating that they have the potential to deliver sustainable pest control in developing countries. It remains to be seen, however, whether the current generation of recombinant baculoviruses will be competitive with the new generation of synthetic chemical pesticides. Current research clearly indicates, though, that the use of biological vectors of genes for insect control will find a place in agriculture. Baculoviruses will also prove valuable in testing the potential utility of proteins and peptides for insect control.

© 2001 Society of Chemical Industry
Toxicity of biorational insecticides: activity against the green peach aphid, Myzus persicae (Sulzer)
Authors: Edelson Jonathan V , Duthie J , Roberts W
Published: September 2002

The relationship between dose for each of four biorational insecticides (pyrethrins, neem extract, capsiacin extract, insecticidal soap) and mortality of the green peach aphid (Myzus persicae) was determined using a laboratory bioassay. These insecticides were toxic to aphids and paired mixtures of the insecticides provided synergistic activity as measured by aphid mortality under the laboratory bioassay conditions. Capsiacin extracts were found to provide low levels of mortality alone but acted synergistically in mixtures with the other insecticides and provided higher than expected levels of mortality. Activity as determined in the laboratory for each insecticide was not evident under field‐use conditions in five separate experiments. Under field conditions and using common application methods, these insecticides did not provide significant levels of control of aphids.

© 2002 Society of Chemical Industry
Insecticidal 2‐hydroxy‐3‐alkyl‐1,4‐naphthoquinones: correlation of inhibition of ubiquinol cytochrome c oxidoreductase (complex III) with insecticidal activity
Authors: Jewess Philip J , Chamberlain Keith , Boogaard Adrian B , Devonshire Alan L , Khambay Bhupinder P S
Published: September 2002

The insecticidal and in vitro activities of four homologous series of 2‐hydroxy and acetoxy‐3‐substituted‐1,4‐naphthoquinones have been measured and correlated with their (Log) octanol/water partition coefficients (Log Ko/w). In vitro activity against mitochondrial complex III was only exhibited by 2‐hydroxy‐3‐alkyl‐1,4‐naphthoquinones, indicating that the 2‐acetoxy compounds act as pro‐insecticides. Good correlation was observed between in vivo activity against the two‐spotted spider mite, Tetranychus urticae and inhibition of complex III isolated from blowfly flight muscle. Both hydroxy and acetoxy analogues of individual compounds exhibited similar levels of in vivo activity with optimum activity for analogues with Log Ko/w values of 7–8. In contrast, the acetoxy derivatives showed superior in vivo activity against the tobacco whitefly, Bemisia tabaci. Complex III isolated from whitefly was optimally inhibited by hydroxy analogues with lower Log Ko/w values (6.0–6.5) and was also more sensitive than the blowfly enzyme to all the compounds tested.

© 2002 Society of Chemical Industry
The response of phosphine‐resistant lesser grain borer Rhyzopertha dominica and rice weevil Sitophilus oryzae in mixed‐age cultures to varying concentrations of phosphine
Authors: Rajendran Somiahnadar , Gunasekaran Nagamuthu
Published: September 2002

The response of Rhyzopertha dominica and Sitophilus oryzae (both phosphine‐resistant) in mixed‐age cultures to phosphine at fixed concentration–time products (CT) of 10 500 to 168 000 µl litre−1 h (ppm h) with either constant, rising or falling concentrations for 7 days was studied at 27(±2) °C. At lower CT products, rising concentrations of phosphine led to significantly fewer survivors of R dominica and S oryzae. Conversely, exposure to falling concentrations of phosphine resulted in significantly more survivors. The influence of changing concentrations of phosphine was more pronounced in S oryzae than in R dominica. In the latter, at the lower CT products of 21 000 and 42 000 µl litre−1 h, the adult stage proved to be most tolerant, contrary to the accepted belief that the egg or pupal stage are always more tolerant to phosphine. The results indicate that application of phosphine in rising concentrations is more effective than in constant or falling concentrations.

© 2002 Society of Chemical Industry
Potential of a novel antibiotic, 2‐methylheptyl isonicotinate, as a biocontrol agent against fusarial wilt of crucifers
Authors: Bordoloi Gojen N , Kumari Babita , Guha Arijit , Thakur Debajit , Bordoloi Manabjyoti , Roy Monoj K , Bora Tarun C
Published: September 2002

Screening for newer bioactive compounds from microbial metabolites resulted in the isolation of a novel antibiotic from the culture filtrate, Streptomyces sp 201, of a soil. The bioactive compound, with antifungal and antibacterial activity, was identified as 2‐methylheptyl isonicotinate. The antifungal activity of live culture, culture broth and the isolated bioactive compound showed marked inhibition against dominant soil‐borne phytopathogens such as Fusarium oxysporum Schlect, F moniliforme Sheldon, F semitectum Berkeley & Ravenel, F solani (Martius) Sacc and Rhizoctonia solani Kuehn. The compound had no effect on seed germination and seedling development as displayed by root and stem growth of the test plant species. In pot experiments with seedlings of cruciferous plants such as Raphanus sativus L (radish), Brassica campestris L (yellow mustard), Brassica oleracea var botrytis L (cauliflower), the antibiotic compound showed promising protective activity of 92% when seeds of the test plants were treated at a dose of 50 µgml−1 prior to sowing. Seed treatment with a spore suspension (3 × 108 spores ml−1) of the Streptomyces sp 201 displayed protective activity in the range of 56–60%. Seeds coated with 2.5% methyl cellulose‐amended spores of the antagonist showed protective activity in the range of 64–72%. Further, seed treatment with the culture filtrate of the antagonist also showed promising protective activity in the range of 64–84%.

© 2002 Society of Chemical Industry
In vivo and in vitro metabolism of fipronil by larvae of the European corn borer Ostrinia nubilalis
Authors: Durham Eric W , Siegfried Blair D , Scharf Michael E
Published: September 2002

In vivo and in vitro metabolism of [14C]fipronil was examined in a susceptible European corn borer (Ostrinia nubilalis, Hübner) laboratory strain. [14C]Fipronil penetrated the larval integument slowly, with 71.5% of the applied radioactivity recovered from surface rinses 24 h after topical application. Despite this slow penetration, radioactivity was detected in both the excrement and internal organo‐soluble fractions. Radioactivity in the internal aqueous fraction and tissue pellet accounted for less than 0.8% of total radioactivity. The in vivo studies suggest that fipronil oxidation to its sulfone metabolite is the major route of metabolic conversion. In vitro studies were performed using subcellular microsomal fractions isolated from European corn borer larval midguts. Cytochrome P450‐dependent monooxygenase activity (methoxyresorufin O‐demethylase) was consistently observed in midgut preparations, and formation and detection of the sulfone metabolite in the same midgut preparations was also NADPH‐dependent and inhibited by piperonyl butoxide. In vitro metabolism results indicate microsomal monooxygenases are responsible for the conversion of fipronil to its sulfone form in the European corn borer.

© 2002 Society of Chemical Industry
Assessment of relevant factors and relationships concerning human dermal exposure to pesticides in greenhouse applications
Authors: Martínez Vidal Jose L , González Francisco J Egea , Frenich Antonia Garrido , Galera María Martínez , Aguilera Pedro A , Carrique Enrique López
Published: September 2002

Principal component analysis (PCA) was applied to the gas chromatographic data obtained from 23 different greenhouse trials. This was used to establish which factors, including application technique (very small, small, medium and large drop‐size), crop characteristics (short/tall, thin/dense) and pattern application of the operator (walking towards or away from the treated area) are relevant to the dermal exposure levels of greenhouse applicators. The results showed that the highest exposure by pesticides during field applications in greenhouses, in the climatic conditions and in the crop conditions typical of a southern European country, occurs on the lower legs and front thighs of the applicators. Similar results were obtained by hierarchical cluster analysis (HCA). Drop‐size seems to be very important in determining total exposure, while height and density of crops have little influence on total exposure under the conditions of the present study. No pesticide type is a major factor in total exposure. The application of multiple regression analysis (MRA) allowed assessment of the relationships between the pesticide exposure of the less affected parts of the body with the most affected parts.

© 2002 Society of Chemical Industry