bluuebunny/crossref_metadata_2025 huggingface dataset:
Some Reactions of Magnesium Arylporphyrazines: Evidence of Dehydroporphyrazine Formation
Authors: Vagin Sergej , Hanack Michael , Kammerer Bernd , Frickenschmidt Antje
Published: September 2004

The reactivity of the 2,3‐dibromobenzo‐annulated 2,3,7,8,12,13‐hexakis(m‐trifluoromethylphenyl)porphyrazine magnesium complex 1 towards butyllithium and tert‐butylmagnesium chloride in the presence of metallic magnesium was studied. It was found that n‐butyllithium reacts mainly with the porphyrazine macrocycle to give tetraazachlorins and other reduction products, similarly to porphyrins. On treatment of 1 with tBuMgCl and Mg, dehydroporphyrazine 4 (arynoporphyrazine) was generated and trapped with furan, confirming the possibility of the formation of a dehydrophthalocyanine. The structures of the products were verified by UV/Vis and NMR spectroscopy, and also mass spectrometry (MALDI‐TOF). Utilization of the tetrapyrrolic macrocycle 1 for this type of reaction may become a new synthetic strategy for unsymmetrical peripheral derivatization of phthalocyanines and related compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Synthesis of two Conformationally Restricted Piperazine Scaffolds for Combinatorial Chemistry
Authors: Opatz Till
Published: September 2004

Piperazines are widely used as central elements in the construction of bioactive molecules. Herein, the short synthesis of two chiral 2,6‐bridged piperazines possessing orthogonally stable protecting groups from readily available starting materials is described. It is suggested that these molecules may be used as conformationally restricted scaffolds for the combinatorial synthesis of drug‐like compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Brominated 4‐(Trifluoromethyl)pyrimidines: A Convenient Access to Versatile Intermediates
Authors: Ondi Levente , Lefebvre Olivier , Schlosser Manfred
Published: September 2004

An expedient route to all three monobrominated and all three dibrominated isomers of 4‐(trifluoromethyl)pyrimidine, and to several other halogenated pyrimidines, is described. Key steps are the electrophilic introduction of the halogen in the 5‐position of 2‐ or 4‐pyrimidinones, the bromodeoxygenation of pyrimidinones or thiopyrimidinones using phosphorus tribromide, and the partial debromination of dibromo‐4‐(trifluoromethyl)pyrimidines. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Arthrobacter sp. JS443‐Based Whole Cell Amperometric Biosensor for p‐Nitrophenol
Authors: Lei Yu , Mulchandani Priti , Chen Wilfred , Wang Joseph , Mulchandani Ashok
Published: September 2004

An amperometric microbial biosensor for highly sensitive and selective determination of p‐nitrophenol (PNP) is reported. The biosensor consisted of PNP‐degrader Arthrobacter sp. JS443 immobilized by entrapment in Nafion polymer deposited on the top of the carbon paste electrode transducer. The biosensor was based on the measurement of the oxidation current of the intermediates 4‐nitrocatechol and 1,2,4‐benzenetriol formed by the highly selective oxidation of PNP by Arthrobacter sp. The sensor signal and response time were optimized with applied potential of +0.4 V (vs. Ag/AgCl reference electrode) and 0.03 mg of cells and operating in pH 7.5, 50 mM citrate‐phosphate buffer at room temperature. When operated at optimized conditions, the Arthrobacter sp.‐based biosensor measured as low as 5 nM (0.7 ppb) of PNP. The biosensor demonstrated excellent selectivity with no interference from phenolic compounds such as 2‐nitrophenol, phenol and 3‐chlorophenol but was interfered by 3‐nitrophenol and 3‐methyl‐4‐nitrophenol. It had good precision and intra‐ and inter‐day reproducibility, accuracy and was stable up to 3 days when stored in buffer at 4 °C. When applied for measurement in water from Lake Elsinore, CA, the results obtained were in excellent agreement with the amounts determined spectrophotometrically.
Frequent p16INK4a promoter hypermethylation in human papillomavirus‐infected female lung cancer in Taiwan
Authors: Wu Ming‐Fang , Cheng Ya‐Wen , Lai Ji‐Ching , Hsu Min‐Chih , Chen Jung‐Ta , Liu Wen‐Shan , Chiou Ming‐Chih , Chen Chih‐Yi , Lee Huei
Published: September 2004

Inactivation of p16INK4a gene through promoter hypermethylation has been frequently observed in non small cell lung cancer; however, various studies have shown a controversial correlation between p16INK4a hypermethylation and cigarette smoking. Our recent report showed that human papillomarvirus (HPV) 16/18 infections were associated with the development of nonsmoking female lung cancer in Taiwan and we further speculated that HPV infection may be linked with p16INK4a hypermethylation. To verify the influence of environmental exposure, including cigarette smoking, environmental carcinogen exposure and HPV infections on p16INK4a hypermethylation, tumors from 162 lung patients, including 67 smoking males, 41 nonsmoking males and 58 nonsmoking females, were subjected to p16INK4a hypermethylation analysis by methylation‐specific PCR. As the results showed, p16INK4a hypermethylation was detected in 40 (59.7%) of 67 smoking male, 15 (36.6%) of 41 nonsmoking male and 35 (60.3%) of 58 nonsmoking female lung tumors. This result seemed to reveal that gender and cigarette smoking both possess an equal influence on p16INK4a hypermethylation. This result also led to a speculation that HPV infection may promote p16INK4a hypermethylation in nonsmoking female lung cancer patients. From our data, p16INK4a hypermethylation frequency in nonsmoking female lung tumors with HPV infection was as high as 70% (30 of 43) compared to those without HPV infection (33%; 5 of 15). In fact, the correlation between HPV infection and p16INK4a hypermethylation was only observed in nonsmoking female lung tumors (p = 0.017), but not in smoking male or nonsmoking male lung tumors. Moreover, the reverse correlation between p16INK4a immunostaining and p16INK4a promoter hypermethylation was also only observed in nonsmoking female lung tumors. These results strongly suggested that the involvement of HPV infection in lung tumorigenesis of nonsmoking female cancer patients in Taiwan may be mediated at least in part through the increase of hypermethylation to cause p16INK4a inactivation.
Prospective study of risk factors for esophageal and gastric cancers in the Linxian general population trial cohort in China
Authors: Tran Gina D. , Sun Xiu‐Di , Abnet Christian C. , Fan Jin‐Hu , Dawsey Sanford M. , Dong Zhi‐Wei , Mark Steven D. , Qiao You‐Lin , Taylor Philip R.
Published: September 2004

Esophageal cancer incidence and mortality rates in Linxian, China are among the highest in the world. We examined risk factors for esophageal squamous cell carcinoma (ESCC), gastric cardia cancer (GCC), and gastric noncardia cancer (GNCC) in a population‐based, prospective study of 29,584 adults who participated in the Linxian General Population Trial. All study participants completed a baseline questionnaire that included questions on demographic characteristics, personal and family history of disease, and lifestyle factors. After 15 years of follow‐up, a total of 3,410 incident upper gastrointestinal cancers were identified, including 1,958 ESCC, 1,089 GCC and 363 GNCC. Cox proportional hazard models were used to estimate risks. Increased age and a positive family history of esophageal cancer (including ESCC or GCC) were significantly associated with risk at all 3 cancer sites. Additional risk factors for ESCC included being born in Linxian, increased height, cigarette smoking and pipe smoking; for GCC, male gender, consumption of moldy breads and pipe smoking; and for GNCC, male gender and cigarette smoking. Protective factors for ESCC included formal education, water piped into the home, increased consumption of meat, eggs and fresh fruits and increased BMI; for GCC, formal education, water piped into the home, increased consumption of eggs and fresh fruits and alcohol consumption; and for GNCC, increased weight and BMI. General socioeconomic status (SES) is a common denominator in many of these factors and improving SES is a promising approach for reducing the tremendous burden of upper gastrointestinal cancers in Linxian.
Tensile properties and biological response of poly(L‐lactic acid) felt graft: An experimental trial for rotator‐cuff reconstruction
Authors: Aoki Mitsuhiro , Miyamoto Shigenori , Okamura Kenji , Yamashita Toshihiko , Ikada Yoshito , Matsuda Shojiro
Published: September 2004

Poly(L‐lactic acid) felt (PLLA felt) was prepared for reconstruction of the rotator cuff in animal models. Small changes were found in the tensile strength of both the cultured PLLA felt and the PLLA felt implanted on the paravertebral muscle of rabbits up to 16 postoperative weeks. The stiffness of the felt implanted on the muscle from 6 to 16 weeks showed a statistically significant increase. When the infraspinatus tendons of beagle dog were reconstructed with the PLLA felt, the ultimate strength of PLLA felt increased threefold, and the stiffness increased fivefold by 16 postoperative weeks compared to that of the initial PLLA felt. They were statistically significant (p < 0.01). All the implanted specimens ruptured at the junction between the bone and the PLLA felt. Histological examination demonstrated infiltration of fibrous tissue into the interstices of the PLLA felt fibers. Connection between the infraspinatus tendon and the PLLA felt was tight with the formed scar tissue, but the connective tissue between the bone and PLLA felt fibers was sparse even at 16 and 32 postoperative weeks. A few deteriorated PLLA felt fibers were observed at 32 postoperative weeks. It was concluded that the degradation rate of PLLA felt was low and the tensile recovery of the PLLA felt graft in beagle dogs was excellent. Thus, PLLA felt might be a useful bioabsorbable material for rotator‐cuff reconstruction. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 252–259, 2004
Exudation of organic anions by roots of cabbage, carrot, and potato as influenced by environmental factors and plant age
Authors: Dechassa Nigussie , Schenk Manfred K.
Published: September 2004

A previous study demonstrated that cabbage was P efficient compared to carrot and potato. However, calculating plant P uptake by a mechanistic simulation model based on P transport by diffusion and mass flow, P uptake of roots according to the Michaelis‐Menten kinetics, and morphological root characteristics including root hairs, revealed that these parameters could explain only 2/5 of the total P uptake of cabbage, but 4/5 of that of carrot and potato (Dechassa et al., 2003). Therefore, it was hypothesized that a higher root exudation of organic anions may enhance P mobilization and hence P uptake of cabbage. The objective of this research was to determine root exudation of organic anions by the three species, and to investigate the influence of plant age and dark/light period on organic‐anion exudation by cabbage. Experiments were conducted in a growth chamber in nutrient solution with or without P. Organic anions were determined in root exudates and in root tissue. With cabbage and potato, P deficiency induced exudation of citrate and succinate, respectively. Citrate‐exudation rate of P‐deficient cabbage plants was correlated with accumulation of citrate in root tissue. In contrast, high succinate‐exudation rates in potato were not correlated with an increased concentration in root tissue. For carrot, no change was observed in the exudation of any of the organic anions in response to P deficiency. The results also showed that succinate‐ and citrate‐exudation rates of cabbage roots increased with increased plant age. There was also a significant increase in exudation rates of organic anions of cabbage roots during the light period of the day. It was concluded that cabbage had the ability to exude large amounts of citrate in response to P deficiency by which it can additionally enhance its P‐uptake efficiency, whereas carrot and potato showed little evidence of possessing such a mechanism.
Microbial biomass and activity in composts of different composition and age
Authors: Gattinger Andreas , Bausenwein Ursula , Bruns Christian
Published: September 2004

The aim of this study was to perform a comparison of microbial activity and biomass in biowaste (BWC), yard waste (YWC), and cattle‐manure composts (CMC) of different age. Two different methods for either biomass (microbial C following fumigation‐extraction and microbial lipid phosphate) or activity measurements (CO2‐production rate and fluorescein diacetate hydrolysis) provided comparable information, as judged from their strong correlation. Microbial biomass and activity declined with time in all composts. Microbial biomass C was strongly correlated with microbial activity but was even stronger correlated with pH. CMC proved to be very distinct from the two other compost types by having the highest biomass and the lowest specific activity (i.e., activity per unit biomass). The microbiological properties analyzed allow us to discriminate among different compost types, helping to assign their potential applications.
A Novel Approach to High Performance Elastomer by Using Clay
Authors: Ma Jun , Xiang Ping , Mai Yiu‐Wing , Zhang Li‐Qun
Published: September 2004

Summary: A novel method was developed to prepare an exfoliated styrene butadiene rubber (SBR)/clay nanocomposite with a strong interface between the clay layers and the rubber. An exfoliation mechanism was proposed and verified based on X‐ray diffraction (XRD)/transmission electron microscopy (TEM) analyses of the intercalation/exfoliation phenomena after each step of the process. The significant improvements of mechanical properties may give the first evidence that both exfoliation and a strong interface play critical roles in nanoreinforcement.

TEM image of a SBR/AA‐clay nanocomposite.

image

TEM image of a SBR/AA‐clay nanocomposite.
Sporadic rapid‐onset dystonia–parkinsonism syndrome: Failure of bilateral pallidal stimulation
Authors: Deutschländer Angela , Asmus Friedrich , Gasser Thomas , Steude Ulrich , Bötzel Kai
Published: September 2004

We report on a woman who had a severe sporadic nonprogressive dystonia–parkinsonism syndrome with rapid onset of symptoms at age 21. Secondary causes for dystonia were ruled out. No response to levodopa/carbidopa was seen. The patient fulfilled all diagnostic criteria of rapid‐onset dystonia–parkinsonism, except for autosomal‐dominant inheritance. Bilateral deep brain stimulation of the globus pallidus failed to alleviate her symptoms. © 2004 Movement Disorder Society
Bounding vertex coloring by truncated multistage branch and bound
Authors: Caramia Massimiliano , Dell'Olmo Paolo
Published: September 2004

In this article we design a truncated enumerative algorithm based on branch and bound rules embedded in a multistage scheme that allows iterative visits of subgraphs. The algorithm is designed to find lower bounds on the chromatic number of graphs, and, by means of simple coloring extension rules, it is often capable of finding optimal solutions. In this issue we obtain a very promising result: our algorithm was able to solve benchmarks DSJC125_5, DSJC125_9, DSJC250_1, DSJR500_1c, and DSJR500_5, which had not previously been solved. Furthermore, we show how our method can be employed in finding upper bounds on the chromatic number, and thus, we compare the upper bound–lower bound gaps so obtained with those achieved by known exact algorithms. The comparison highlights that in more than half of the tested benchmarks the gap obtained by our algorithm was lower than that obtained by a recent branch and cut method and by the well‐known DSATUR algorithm. To provide a deeper analysis we finally compare the upper bounds found by the proposed algorithm on the same benchmarks with the best heuristic solutions known in the open literature. Also, in this case, the proposed truncated branch and bound was often able to outperform these heuristic solutions. © 2004 Wiley Periodicals, Inc. NETWORKS, Vol. 44(4), 231–242 2004
Impact fracture toughness of polyethylene/polypropylene multilayers
Authors: Moreno Luisa , Leevers Patrick
Published: September 2004

In a number of applications, a brittle polymeric surface layer is deliberately molded onto a tough substrate for decorative or protective purposes. This can increase the susceptibility of the tough polymer to premature failure. Similar problems arise when a surface layer becomes embrittled by environmental effects. Choosing a surface material that has good mechanical properties without having this effect can be difficult. In this work the fracture resistances of two polyethylenes and an ethylene/propylene copolymer, and of symmetrical two‐component multilayers of these polymers, were determined as a function of temperature, using instrumented impact tests. The law of mixtures accounts adequately for the fracture resistance of multilayer structures where there is no mechanical interaction between skin and core. However, it gave misleading results for a structure in which high skin modulus at low temperatures appeared to influence the fracture resistance of the core through a constraint effect. Polym. Eng. Sci. 44:1627–1635, 2004. © 2004 Society of Plastics Engineers.
Rheo‐kinetic measurement of thermoplastic polyurethane polymerization in a measurement kneader
Authors: Verhoeven V. W. A. , Van Vondel M. P. Y. , Ganzeveld K. J. , Janssen L. P. B. M.
Published: September 2004

The rheo‐kinetics of thermoplastic polyurethane (TPU) formation was investigated in a measurement kneader at high temperatures. The TPU was made of a polyester polyol, methyl‐propane‐diol and a 50/50 mixture of 2,4′‐ and 4,4′‐diphenylmethane diisocyanate (MDI). The reaction proceeded according to a second order reaction for which the kinetic constants were determined by size exclusion chromatography (SEC) analysis. The activation energy was found to be equal to 61.3 kJ/mol, and the pre‐exponential factor was equal to 2.18e6 mol/kg K. For the temperature range under investigation, the flow activation energy was equal to 42.7 kJ/mol, which is comparable to that of a linear polymer. This indicates that the hard segments are completely dissolved at the temperatures investigated. The initial part of the reaction was much faster than anticipated from the kinetic measurements. Diffusion limitations at higher conversions probably cause this decrease in reaction velocity. At longer reaction times, the molecular weight leveled off because of depolymerization. Therefore, additional experiments are necessary to describe the complete polymerization of thermoplastic polyurethane. Polym. Eng. Sci. 44:1648–1655, 2004. © 2004 Society of Plastics Engineers.
Flow‐induced morphology of cast polypropylene
Authors: Yin Bo , Yang Wei , Yu Qing‐shun , Yang Ming‐bo
Published: September 2004

The crystal structures of different grades of cast polypropylene (CPP) extrudates were characterized by Differential Scanning Calorimetry (DSC) and Wide Angle X‐ray Diffraction (WAXD). The effects of the crystallization temperature, draw ratio, and cooling rate on crystal structure are discussed in detail. The results demonstrate that stretching cannot induce the formation of the γ crystal, but the crystallization temperature and the cooling rate do affect the formation of the γ crystal. The slower the cooling rate, the more easily the γ crystal develops. It was found that at the optimum crystallization temperature (Tc) of about 110°C, the γ crystal developed distinctly, and a slower cooling rate made the formation of γ crystal easier. Also, the crystal structures of different resins at the same conditions were discriminative, suggesting that the formation of the γ crystal was due to interruptions of comonomer units in the isotactic propylene sequences, which prevented the PP chain segment from entering the crystal lattice of the α crystal in some degree. If the length of the comonomer sequences was shorter and the distribution of the comonomer units more symmetrical, the formation of the γ crystal would be more distinct. Polym. Eng. Sci. 44:1656–1661, 2004. © 2004 Society of Plastics Engineers.
Injection moldability and properties of compatibilized PA6/LDPE blends
Authors: Canfora L. , Filippi S. , La Mantia F. P.
Published: September 2004

An ethylene‐acrylic acid copolymer (EAA), either alone or combined with a low molar mass bis‐oxazoline compound (PBO), has been used as a compatibilization promoter for blends of polyamide‐6 (PA6) with low‐density polyethylene (LDPE). The effect of compatibilization on blend processability in injection molding operations and on the properties of the molded specimens has been studied. In the absence of compatibilization, the injection molded articles were shown to have low‐quality surface appearance and poor mechanical properties. Both these characteristics were appreciably improved as a result of reactive compatibilization of the blends with EAA and, even more, with the EAA‐PBO couple. In fact, the finished articles prepared by injection molding of the quaternary blends were shown to possess good surface appearance, fine and stable morphology and satisfactory mechanical properties. The results confirm the conclusion of a previous study, i.e., that the PBO fourth component may promote the in situ formation of PA6‐g‐EAA copolymers, by reaction with both the functional groups of PA6 and the carboxyl groups of EAA. Polym. Eng. Sci. 44:1732–1737, 2004. © 2004 Society of Plastics Engineers.
A low‐cost, low‐fiber‐breakage, injection molding process for long sisal fiber reinforced polypropylene
Authors: Arzondo L. M. , Vazquez A. , Carella J. M. , Pastor J. M.
Published: September 2004

Composites of polypropylene (PP) and non‐treated sisal fiber (SF) were prepared in a non‐conventional two‐step process that offers significant advantages. Maleic anhydride–grafted polypropylene (MA‐g‐PP) was used as a coupling agent, to improve adhesion between the polar sisal fiber and the non‐polar polypropylene continuous matrix. At a first step, SF/MA‐g‐PP pellets with large aspect ratio and very high fiber content are prepared by extrusion impregnation and coating of a continuous SF yarn, followed by cooling and cutting. The composite pellets are thus dry blended with regular PP pellets in the injection machine hopper, and injected to obtain composite tensile specimens with a minimum quantity of expensive MA‐g‐PP, minimum fiber breakage and thermal degradation, and excellent mechanical properties. The SF/MA‐g‐PP pellets have a fiber content of 70% (w/w). The composite tensile specimens have final fiber contents ranging from about 3.5% to 24.5% (w/w). The PP tensile strength rises by about 44%. The tensile modulus increases by 126%, and the heat distortion temperature (HDT) is raised by about 35 K. FT‐IR spectroscopy and SEM micrographic observation show that the MA‐g‐PP is covalently bonded to SF through esterification. Besides the improvement in mechanical and thermal properties, costs are reduced because of the lower content of very expensive MA‐g‐PP, and the use of a single‐screw extruder at high production rates. Polym. Eng. Sci. 44:1766–1772, 2004. © 2004 Society of Plastics Engineers.
Impact strength and elongation‐to‐break of compatibilized ternary blends of polypropylene, nylon 66, and polystyrene
Authors: Debolt Michael A. , Robertson Richard E.
Published: September 2004

The Izod impact strength and tensile elongation‐to‐break were measured for blends of nylon 66 and polystyrene in a polypropylene matrix with and without compatibilization by an ionomer resin (for nylon 66) and a styrene‐block‐ethylene‐co‐butylene‐block‐styrene copolymer (for polystyrene). With 20% nylon 66 and 20% polystyrene, about 5% of each compatibilizer was optimal. When used together for the ternary blend, there seemed to be little gross interference (or synergism) between the compatibilizers. A comparison between binary blends suggests that what interaction does exists may be synergistic. Polym. Eng. Sci. 44:1800–1809, 2004. © 2004 Society of Plastics Engineers.
Convergence and computation of describing functions using a recursive Volterra series
Authors: Glass J. W. , Franchek M. A.
Published: September 2004

Presented in this paper is a comparison of algorithms for computing an approximation to the sinusoidal input describing function (SIDF) for the nonlinear differential equation
ẏ(t)+b1y(t)+b2u2(t)y(t) = K(u̇(t)+b3u(t))
The importance of this nonlinear differential equation comes from the context of nonlinear feedback controller design. Specifically, this equation is either a linear lead or lag controller (depending on the coefficient values) augmented with a nonlinear, polynomial type term. Consequently, obtaining a SIDF representation of this nonlinear differential equation or creating a process to obtain SIDFs for other similar differential equations, will facilitate nonlinear controller design using classical loop shaping tools. The two SIDF approximations studied include the well‐established harmonic balance method and a Volterra series based algorithm. In applying the Volterra series, several theoretical issues were addressed including the development of a recursive solution that calculates high order Volterra transfer functions, and the guarantee of convergence to an arbitrary accuracy. Throughout the paper, case studies are presented. Copyright © 2004 John Wiley & Sons, Ltd.
High interannual variation in the hatching sex ratio of Tengmalm's owl broods during a vole cycle
Authors: Hipkiss Tim , Hörnfeldt Birger
Published: September 2004

The sex ratio at hatching in broods of Tengmalm's owl (Aegolius funereus) in northern Sweden was investigated for 3 years characterized by different phases of the vole and owl cycle. Previous work showed the sex ratio in this species to be male‐biased for 1 year with a favourable food supply, and that in feeding experiments male nestlings (but not females) suffered higher mortality when food was limited, but not otherwise. Here we present data from a complete 3‐year owl cycle, showing that mean brood sex ratio varied significantly among years, being male‐biased (65% males) in the first year of high owl breeding density, unbiased (49%) in the second year of high owl breeding density, and female‐biased (33% males) in the owls’ low year. Brood sex ratio did not vary significantly within years with laying date or parental age. Vole availability, and therefore the owls’ food supply, declined during the 3 years studied. Tengmalm's owl parents thus appear to adaptively adjust the sex ratio of their broods according to the expected annual mortality risk of sons.
Separation–individuation revisited: on the interplay of parent–adolescent relations, identity and emotional adjustment in adolescence☆
Authors: Meeus Wim , Iedema Jurjen , Maassen Gerard , Engels Rutger
Published: September 2004

The objective of this study was to test our alternative interpretation of the separation–individuation hypothesis. This interpretation states that separation from the parents is not a precondition for individuation, but rather separation and individuation are two parallel processes of development during adolescence. We investigated our interpretation in two ways. Firstly, we looked at descriptive age differences in parental support and development of relational and societal identity. Secondly, we investigated the variation with age of the associations between parental support and emotional adjustment, and identity and emotional adjustment. Data of a representative Dutch sample of 2814 adolescents, aged 12–24 were used. In both cases, the findings supported our interpretation of the separation–individuation hypothesis and similar results were found in the descriptive analyses and the structural equation models. Parental support decreased with age, and so too did its association with emotional adjustment. In other words, as adolescents become older, they experience less parental support, while its importance for their emotional adjustment also declines. The opposite pattern was observed with respect to identity development: as adolescents become older, their relational and societal identity commitments develop, and the degree to which these commitments are developed also becomes more important for their emotional adjustment.
N‐glycosylation is required for efficient secretion of a novel human secreted glycoprotein, hPAP21
Authors: Zhou Yu-Bo , Liu Feng , Zhu Zhi-Dong , Zhu Hong , Zhang Xin , Wang Zhi-Qin , Liu Jian-Hua , Han Ze-Guang
Published: September 2004

The present study reported the isolation and characterization of a novel human secreted protein, named as hPAP21 (human protease‐associated domain‐containing protein, 21 kDa), encoded by the hypothetical gene chromosome 2 open reading frame 7 (C2orf7) that contains signal peptide in its N‐terminus, without transmembrane domain, except for PA domain in its middle. Western blotting assay indicated that the c‐Myc tagged hPAP21 could be secreted into culture medium in the transfected Chinese hamster ovary cells. However, the molecular weights, whatever intracellular (28 kDa) or extracellular (30 kDa) forms, are larger than that of the prediction. To define whether the glycosylation was important process for its secretion, endoglycosidase H (Endo H) and PNGase F (PNG F) were employed to evaluate the effect of glycosylation types on secretion of hPAP21. Interestingly, the extracellular forms were primarily sensitive to PNG F, not Endo H, implying that complex N‐glycosylation could be required for the secretion of hPAP21. Furthermore, N‐glycosylation of Asn171 was confirmed as potential crucial process for the secretory protein via site‐directed mutagenesis assay. All data will be contributed to the understanding of molecular functions of hPAP21.
Small antisense RNA to cyclin D1 generated by pre‐tRNA splicing inhibits growth of human hepatoma cells
Authors: Lai Dazhi , Weng Shaojie , Wang Cui'e , Qi Lianquan , Yu Changming , Fu Ling , Chen Wei
Published: September 2004

Introns are present in some human pre‐tRNAs. They are spliced out during the maturation processes of pre‐tRNAs in a way that is irrelevant to their specific nucleotide sequences. This unique characteristic of tRNA splicing can be used for generation of small antisense RNAs by replacing the intron sequences with corresponding antisense sequences. In this work, the intron sequence of human pre‐tRNAtyr gene was replaced with a 20 bp antisense sequence targeted to the 5′ coding region of cyclin D1, a molecule that was over‐expressed in many malignant proliferating cells. Under the control of U6 SnRNA promoter to further enhance transcription efficiency of the modified pre‐tRNAtyr gene and subsequent antisense generation, the antisense RNA exhibited obvious suppression of cyclin D1 expression in H22 hepatoma cells. The growth of H22‐transplanted tumors in mice was significantly inhibited when treated with naked plasmid DNA harboring the cyclin D1 antisense RNA generating cassette. Such tumor growth inhibition might be due to apoptosis caused by reduced cyclin D1 expression as revealed by immunohistochemical analysis of tumor samples.
A Meeting with History
Authors: Carson Zosia
Published: September 2004

In 2003 I was one of the lucky recipients to be awarded a BIALL bursary to attend the 22nd Annual Course on International Law Librarianship from the 21st to 25th September held in Cape Town, South Africa. This is my personal report of my experiences which I would like to share with LIM readers. My report will focus on four aspects:

1. Robben Island

2. Ahmed Kathrada

3. A meeting with history

4. Final impressions
Joint Study Institute, Sydney, Australia – 20–23 February 2004
Authors: Bowl Catherine , Worley Loyita
Published: September 2004

Between us we have attended all the Joint Study Institutes (JSIs) and both had a particular interest in attending the one in Sydney, not least because it was the last in the present cycle. The location of Sydney itself was a great draw and most of the delegates made attendance at the JSI part of a holiday and took the opportunity to visit other parts of Australia at the same time.
Elevation of lung surfactant phosphatidylcholine in mouse models of Sandhoff and of Niemann–Pick A disease
Authors: Buccoliero R. , Ginzburg L. , Futerman> A. H.
Published: September 2004

Summary: Sandhoff disease is caused by the defective activity of the lysosomal enzyme β‐hexosaminidase, resulting in accumulation of the glycolipids, GA2 and GM2. Niemann–Pick A/B disease is caused by the defective activity of lysosomal acid sphingomyelinase resulting in sphingomyelin accumulation. Pulmonary complications have been observed in both diseases. We now demonstrate changes in phospholipid levels in pulmonary surfactant in mouse models of these diseases. In the Hexb mouse, a model of Sandhoff disease, lipid phosphate levels were elevated in surfactant from 3‐ and 4‐month‐old mice, which was mainly due to elevated levels of phosphatidylcholine. In the ASM mouse, a model of Niemann–Pick A disease, levels of the primary storage material, sphingomyelin, were elevated as expected, and levels of phosphatidylcholine and two other phospholipids were also significantly elevated in pulmonary surfactant and in lung tissue from 5‐, 6‐ and 7‐month‐old mice. These results suggest that changes in phospholipid levels and composition in lung surfactant might be a general feature of sphingolipid storage diseases, which may be in part responsible for the increased susceptibility of these patients to respiratory infections and lung pathology, often the main reason for the death of these patients.
Severe neonatal onset of glycogenosis type IV: Clinical and laboratory findings leading to diagnosis in two siblings
Authors: Giuffrè B. , Parini R. , Rizzuti T. , Morandi L. , van Diggelen O. P. , Bruno C. , Giuffrè M.
Published: September 2004

Summary: Glycogenosis type IV is an autosomal recessive disease, exceptionally diagnosed at birth: only very few reports of the fatal perinatal neuromuscular form have been described. We report on two sibling male newborns who died at 10 and 4 weeks of age with clinical signs of a systemic storage disease. Prenatal history included polyhydramnios, reduced fetal movements and fetal hydrops, Caesarean section was performed at 36 weeks of gestational age because of fetal distress. At birth, both babies showed severe hypotonia, hyporeflexia and no spontaneous breathing activity. They never showed active movements, sucking and swallowing and were respirator‐dependent until death. A muscle biopsy revealed, in both patients, the presence of PAS‐positive and partially diastase‐resistant cytoplasmic inclusions containing granular and filamentous amylopectin‐like material. This suggested that the stored material consisted of abnormal glycogen. At autopsy, ultrastructural examination of cardiac and skeletal muscle, liver, kidney and brain showed PAS‐positive diastase‐resistant eosinophilic cytoplasmic inclusions. Determination of branching enzyme activity, in cultured fibroblasts from the second patient, showed markedly reduced enzyme activity, confirming diagnosis of glycogenosis type IV. Our patients showed the full spectrum of both prenatal signs (hydrops, polyhydramnios) and postnatal signs (hypotonia, hyporeflexia, absence of active movements, cardiomegaly), which have been reported previously. They suffered from a very severe form of glycogenosis type IV with clinical and histological involvement of many tissues and organs. Diagnosis was accomplished on the second baby and required several biochemical and histological studies, in order to rule out both neuromuscular disorders and the most common storage diseases with neonatal onset. In our experience, the correct interpretation of the histological findings was essential in the search for the diagnosis.
Assessment of an electron‐impact GC‐MS method for organic acids and glycine conjugates in amniotic fluid
Authors: Kumps A. , Vamos E. , Mardens Y. , Abramowicz M. , Genin J. , Duez P.
Published: September 2004

Summary: We assessed the reliability of a method designed for common electron‐impact GC‐MS systems to determine in a single run most organic acids and glycine conjugates of clinical interest in amniotic fluid. Suitable sensitivity was achieved by dividing the selected‐ion chromatogram into 12 time segments during which the monitoring dwelt on specific ions. Twelve metabolites were simultaneously quantified in amniotic fluid, with performances ranging from very good to clinically acceptable. The total coefficient of variation was 2.5–14.1% and the detection limit was well below the lower value of the physiological range. For five other metabolites, the precision was lower and/or the detection limit was near the physiological range. The method was clinically assessed by the prenatal detection of three cases of tyrosinaemia type I and one case of propionic acidaemia. Analytical and clinical evaluation of the method showed that GC‐MS with electron‐impact fragmentation can be an informative analytical approach for low‐level organic acids in physiological fluids. Apart from the case of glycine conjugates, the method shows a fair reliability for amniotic fluid analysis, which might warrant its use for prenatal diagnosis of organic acidurias. However, this method cannot replace procedures using isotopic internal standards, nor GC‐MS based on chemical ionization fragmentation, which remain confirmatory analytical methods of choice.
Improvement of CDG diagnosis by combined examination of several glycoproteins
Authors: Fang J. , Peters V. , Körner C. , Hoffmann G. F.
Published: September 2004

Summary: Congenital disorders of glycosylation (CDG) represent a family of genetic diseases with broad clinical presentation. Initial diagnosis is currently mainly based on the identification of hyposialylated serum transferrin (TF) by isoelectric focusing (IEF). To improve the diagnosis of known CDG types and to identify so far unknown CDG cases, additional glycoproteins, α1‐antitrypsin (α1‐AT) and α1‐antichymotrypsin (α1‐ACT), were studied. According to the patterns of transferrin, enzyme assays and mutation analysis, 16 patients with various clinical symptoms suspicious for CDG were divided into three groups: group A (n = 6) with confirmed CDG; group B (n = 4) with clear abnormal TF‐IEF patterns of unknown origin (all known CDG types were excluded) and group C (n = 6) with borderline TF‐IEF patterns; 164 samples served as a control group. Automated IEF of TF, α1‐AT and α1‐ACT was carried out using a PhastSystem. CDG patients with glycosylation defects of known origin (group A) and patients with abnormal TF‐IEF patterns due to glycosylation defects of as yet unknown origin (group B) showed abnormal IEF patterns of all three glycoproteins. These results confirmed generalized defects of glycosylation. Furthermore, the IEF pattern of α1‐ACT seems to allow a differentiation between CDG Ia and CDG Ic. However, patients with borderline TF‐IEF pattern (group C) showed a normal α1‐AT‐IEF pattern. Four of these six patients also showed a normal α1‐ACT‐IEF pattern; this constellation suggests that CDG can most likely be excluded. In the two remaining patients of group C with a borderline TF‐IEF pattern an abnormal pattern of α1‐ACT‐IEF was obtained which needs further investigations. We conclude that the combined investigation of three glycoproteins provides additional information in the diagnostic work‐up of patients with possible CDG. The suspicion of CDG in patients with apparent glycosylation defects of unknown origin or borderline TF‐IEF pattern can be either substantiated or weakened.
Mantle heterogeneity beneath eastern California from magnetotelluric measurements
Authors: Park Stephen K.
Published: September 2004

A 300 km long magnetotelluric profile across the Great Valley, Sierra Nevada, and California Basin and Range reveals minimum resistivity differences of 1 order of magnitude at depths from Moho at 30–35 km to depths greater than 200 km. Horizontal wavelengths of 25 km are seen for these changes at depths shallower than 100 km, and the Isabella high seismic wave speed anomaly is present in the section between depths of 100 and 200 km as a minimum tenfold resistivity increase. A transformation from electrical resistivity to temperature and melt fraction using a petrological model and laboratory measurements reveals that partial melt is relatively uncommon and confined primarily to depths between 30 and 100 km. The remainder of the observed resistivity variation is attributed to lateral variations in temperature. Predicted melt fractions match those inferred from Miocene‐Quaternary xenoliths, but modeled temperatures are ∼200°C higher than inferred from thermobarometric analyses of the xenoliths. Possible causes for this discrepancy include an incorrect starting material for the petrological model, exotic conductive phases, higher conductivity due to oxidation state and/or iron content, and diffusion of ions through the solid matrix. I show that hydrogen diffusion or higher oxygen concentrations are plausible explanation for the higher model temperatures. Less than 200 ppm H/106 Si in olivine would increase the conductivity of the matrix sufficiently to allow temperatures inferred from the resistivity section to match those from the xenoliths. A possible source of the hydrogen would be fragments of sinking, metasomatized mantle lithosphere that melted during Cenozoic delamination.
A multiple‐scale simulation of variations in atmospheric carbon dioxide using a coupled biosphere‐atmospheric model
Authors: Nicholls Melville E. , Denning A. Scott , Prihodko Lara , Vidale Pier‐Luigi , Baker Ian , Davis Kenneth , Bakwin Peter
Published: September 2004

Variations of atmospheric CO2 at regional scales are becoming increasingly important in understanding regional carbon budgets, yet the processes that drive them remain relatively unexplored. A simulation was conducted to test a coupled biosphere‐atmospheric model (SiB2‐RAMS), by comparing with measurements made at the WLEF‐TV tower in Wisconsin, and to investigate some of the mechanisms leading to CO2 variability, both on local and regional scales. The simulation was run for a 5‐day period from 26 to 30 July 1997. Multiple nested grids were employed, which enabled mesoscale features to be simulated and which resolved small‐scale features in the vicinity of the WLEF tower. In many respects the model was successful at simulating observed meteorological variables and CO2 fluxes and concentrations. The two most significant deficiencies were that excessive nighttime cooling occurred on two of the nights and that late afternoon uptake of CO2 was larger than observed. Results of the simulation suggest that in addition to biological processes causing variations in CO2 concentrations at the WLEF site other factors, such as small nearby lakes, turbulence induced by vertical wind shear, boundary layer thermals, and clouds, also had significant impacts. These factors add to the difficulty of interpreting CO2 measurements. Regional‐scale patterns of CO2 variability caused by meteorological processes were also identified. Katabatic winds had a significant effect by causing respired CO2 to pool in valleys and along the shores of the Great Lakes during the night. Furthermore, a large diurnal cycle of CO2 concentration occurred over the lakes, which appeared to be mainly due to the combined action of katabatic winds, ambient winds, and the lake breeze circulation. These results suggest that meteorological processes associated with the complex terrain in this region leads to substantial CO2 advection. Therefore meteorological as well as biological processes are likely to be important causes of regional‐scale CO2 variability in the Great Lakes region. A sensitivity test conducted to examine the differences between using a turbulent kinetic energy based subgrid‐scale scheme versus a deformation‐type subgrid‐scale scheme showed advantages and disadvantages to both approaches. Our results suggest that continuous records of CO2 variability measured over heterogeneous continental regions must be interpreted with caution because of the impact of mesoscale circulations on the concentration time series.
Interface disorder and inhomogeneous broadening of quantum well excitons: Do narrow lines always imply high-quality interfaces?
Authors: Ponomarev I. V. , Deych L. I. , Lisyansky A. A.
Published: September 2004

It is a commonly assumed that narrow lines in absorption or luminescence of quantum well excitons at low temperatures indicates high quality of quantum well interfaces. We show, that at least for narrow quantum wells, this is not always the case. Correlations between morphological fluctuations of two interfaces confining a quantum well, which were neglected in previous studies of exciton line shape, strongly suppress an inhomogeneous broadening due to interface disorder.
Direct observation of magnetically induced phase separation in Co-W sputtered thin films
Authors: Oikawa K. , Qin G. W. , Sato M. , Okamoto S. , Kitakami O. , Shimada Y. , Fukamichi K. , Ishida K. , Koyama T.
Published: September 2004

Phase separation of Co-W sputtered thin films having a large magnetocrystalline anisotropy energy have been investigated. A nanoscale compositional fluctuation caused by magnetically induced phase separation was directly confirmed in the films deposited on a heated substrate in analogy with Co-Cr-based alloys. The difference between the phase separation features in Co-W and Co-Cr is attributed to the difference in their elastic energy. It is expected that the phase separation is enhanced by selecting optimum sputtering conditions. The Co-W system, therefore, is considered to be a promising candidate as a base alloy system for high-density recording media.
Virus detection using nanoelectromechanical devices
Authors: Ilic B. , Yang Y. , Craighead H. G.
Published: September 2004

We have used a resonating mechanical cantilever to detect immunospecific binding of viruses, captured from liquid. As a model virus, we used a nonpathogenic insect baculovirus to test the ability to specifically bind and detect small numbers of virus particles. Arrays of surface micromachined, antibody-coated polycrystalline silicon nanomechanical cantilever beams were used to detect binding from various concentrations of baculoviruses in a buffer solution. Because of their small mass, the 0.5μm×6μm cantilevers have mass sensitivities on the order of 10−19g∕Hz, enabling the detection of an immobilized AcV1 antibody monolayer corresponding to a mass of about 3×10−15g. With these devices, we can detect the mass of single-virus particles bound to the cantilever. Resonant frequency shift resulting from the adsorbed mass of the virus particles distinguished solutions of virus concentrations varying between 105 and 107pfu∕ml. Control experiments using buffer solutions without baculovirus showed small amounts (<50attograms) of nonspecific adsorption to the antibody layer.
Spin interferometry with electrons in nanostructures: A road to spintronic devices
Authors: Zülicke U.
Published: September 2004

The wave nature of electrons in semiconductor nanostructures results in spatial interference effects similar to those exhibited by coherent light. The presence of spin–orbit coupling renders interference in spin space and in real space interdependent, making it possible to manipulate the electron’s spin state by addressing its orbital degree of freedom. This suggests the utility of electronic analogs of optical interferometers as blueprints for new spintronics devices. We demonstrate the usefulness of this concept using the Mach–Zehnder interferometer as an example. Its spin-dependent analog realizes a spin-controlled field-effect transistor without magnetic contacts and may be used as a quantum logical gate.
Observation of stacking faults in strained Si layers
Authors: Bedell S. W. , Fogel K. , Sadana D. K. , Chen H. , Domenicucci A.
Published: September 2004

Defects in strained Si layers grown on relaxed SiGe layers were studied using chemical etching and transmission electron microscopy. Defect densities were measured in strained Si layers formed on SiGe buffer layers grown on bulk Si, as well as silicon–germanium-on-insulator substrates. It is found that, in addition to threading dislocations and dislocation pile ups, stacking faults are present in nearly all of the materials studied. The stacking faults are shown to originate in the relaxed SiGe alloy suggesting that they form during the relaxation of the SiGe layer.