bluuebunny/crossref_metadata_2025 huggingface dataset:
Gene conjugation of molecular adjuvant C3d3 to hCGβ increased the anti‐hCGβ Th2 and humoral immune response in DNA immunization
Authors: Wang Xiu‐Li , Zhao Xin‐Rong , Yu Min , Yuan Min‐Min , Yao Xiao‐Ying , Li Da‐Jin
Published: January 2006

Human chorionic gonadotropin (hCG) has been used as an anti‐fertility vaccine and as a target for cancer immunotherapy. We have explored the use of three copies of C3d in DNA vaccine as molecular adjuvant to improve the immunogenicity of this hormone in previous work and found that the immune response induced by pcDNA3‐hCGβ‐C3d3 has been enhanced 243‐fold compared with pcDNA3‐hCGβ following DNA immunization in BALB/c mice. In the present study, a new functionally active DNA vaccine of hCGβ‐C3d3 chimera based on pCMV4 vector has been described. We compared the expression efficiency of pCMV4 and pcDNA3 eukaryotic vectors for hCGβ and hCGβ‐C3d3 fusion protein and the immune response of mice immunized with pcDNA3‐hCGβ, pCMV4‐hCGβ, pcDNA3‐hCGβ‐C3d3 and pCMV4‐hCGβ‐C3d3, respectively, at 25, 50 and 100 pmol dose, and further analyzed the levels of Th1 and Th2 cytokines produced by spleen lymphocytes of the immunized mice upon hCG restimulation in vitro. It was found that pCMV4 vector achieved 1.3–1.5‐fold higher protein expression and raised 1.1–1.2 (primary) and 1.2–1.3 (booster) logs higher titer of anti‐hCGβ IgG than pcDNA3. Mice vaccinated with 50 pmol of hCGβ‐C3d3‐DNAs elicited the highest titer of hCGβ‐specific antibody among the serial doses and the immune response induced by pCMV4‐hCGβ‐C3d3 were, respectively, 1.3, 1.3 and 1.2 logs higher than that of pcDNA3‐hCGβ‐C3d3 and 2.2, 2.9 and 2.4 logs higher than that of pCMV4‐hCGβ at week 2 following the booster immunization. Moreover, we observed that the production of IL‐4 and IL‐10 increased in mice vaccinated with hCGβ‐C3d3‐DNAs and the ratio of IL‐4/IFN‐γ showed a Th2 bias of immune response in the mice immunized with hCGβ‐C3d3‐DNAs. These findings indicated that gene fusion of C3d3 to hCGβ, as a means of harnessing the adjuvant potential of the innate immune system, may improve the antigen‐specific Th2 humoral immune response of the hCGβ DNA vaccine and the pCMV4 vector is a more ideal eukaryotic vector for DNA vaccine than pcDNA3. Copyright © 2006 John Wiley & Sons, Ltd.
Domination in a graph with a 2‐factor
Authors: Kawarabayashi Ken‐ichi , Plummer Michael D. , Saito Akira
Published: January 2006

Let γ(G) be the domination number of a graph G. Reed 6 proved that every graph G of minimum degree at least three satisfies γ(G) ≤ (3/8)|G|, and conjectured that a better upper bound can be obtained for cubic graphs. In this paper, we prove that a 2‐edge‐connected cubic graph G of girth at least 3k satisfies $\gamma (G)\le (({3k+2}))/({9k+3})|G|$. For $k\ge 3$, this gives $\gamma (G)\le ({11}/{30})|G|$, which is better than Reed's bound. In order to obtain this bound, we actually prove a more general theorem for graphs with a 2‐factor. © 2006 Wiley Periodicals, Inc. J Graph Theory 52: 1–6, 2006
On connectivity in graphs with given clique number
Authors: Hellwig Angelika , Volkmann Lutz
Published: January 2006

We consider finite, undirected, and simple graphs G of order n(G) and minimum degree δ(G). The connectivity κ(G) for a connected graph G is defined as the minimum cardinality over all vertex‐cuts.

If κ(G) < δ(G), then Topp and Volkmann 7 showed in 1993 for p‐partite graphs G that

As a simple consequence, Topp and Volkmann obtained for p‐partite graphs G the identity κ(G) = δ(G), if

In this article, we will show that these results remain true for graphs G with ω(G) ≤ p, where ω(G) denotes the clique number of G. Since each p‐partite graph G satisfies ω(G) ≤ p, this generalizes the results of Topp and Volkmann. © 2006 Wiley Periodicals, Inc. J Graph Theory 52: 7–14, 2006
Signed graph factors and degree sequences
Authors: Hoffman Dean , Jordon Heather
Published: January 2006

For a signed graph G and function $f: V(G) \rightarrow Z$, a signed f‐factor of G is a spanning subgraph F such that sdegF(υ) = f(υ) for every vertex υ of G, where sdeg(υ) is the number of positive edges incident with v less the number of negative edges incident with υ, with loops counting twice in either case. For a given vertex‐function f, we provide necessary and sufficient conditions for a signed graph G to have a signed f‐factor. As a consequence of this result, an Erdős‐Gallai‐type result is given for a sequence of integers to be the degree sequence of a signed r‐graph, the graph with at most r positive and r negative edges between a given pair of distinct vertices. We discuss how the theory can be altered when mixed edges (i.e., edges with one positive and one negative end) are allowed, and how it applies to bidirected graphs. © 2006 Wiley Periodicals, Inc. J Graph Theory 52: 27–36, 2006
Sodium tungstate decreases the phosphorylation of tau through GSK3 inactivation
Authors: Gómez‐Ramos Alberto , Domínguez Jorge , Zafra Delia , Corominola Helena , Gomis Ramon , Guinovart Joan J. , Avila Jesús
Published: January 2006

Tungstate treatment increases the phosphorylation of glycogen synthase kinase‐3β (GSK3β) at serine 9, which triggers its inactivation both in cultured neural cells and in vivo. GSK3 phosphorylation is dependent on the activation of extracellular signal‐regulated kinases 1/2 (ERK1/2) induced by tungstate. As a consequence of GSK3 inactivation, the phosphorylation of several GSK3‐dependent sites of the microtubule‐associated protein tau decreases. Tungstate reduces tau phosphorylation only in primed sequences, namely, those prephosphorylated by other kinases before GSK3β modification, which are serines 198, 199, or 202 and threonine 231. The phosphorylation at these sites is involved in reduction of the interaction of tau with microtubules that occurs in Alzheimer's disease. © 2006 Wiley‐Liss, Inc.
Preconditioning with thrombin can be protective or worsen damage after endothelin‐1‐induced focal ischemia in rats
Authors: Henrich‐Noack Petra , Striggow Frank , Reiser Georg , Reymann Klaus G.
Published: January 2006

The serine protease thrombin has shown direct neuroprotective and neurotoxic effects on brain tissue in cerebral ischemia. Previous data suggested that thrombin‐induced protection in vivo can be achieved by preconditioning rather than by acute treatment. In the current work, we used a model of mild ischemia to investigate the effects of preischemic intracerebral thrombin injection on neural damage. By intracerebral injection of endothelin‐1 in freely moving animals, we achieved middle cerebral artery occlusion (MCAO), and 7 days postischemia we performed histological quantification of the infarct areas. Thrombin was injected as a preconditioning stimulus intracerebrally 7 days or 2 and 3 days before ischemia. For acute treatment, thrombin was injected 20 min before MCAO. Thrombin induced significant neuroprotection when given 7 days before endothelin‐1‐induced MCAO but was deleterious when given 2 and 3 days before the insult. The deleterious effect was not seen when thrombin was given acutely before ischemia. Our data demonstrate that preconditioning with thrombin can protect against damage or worsen ischemic damage. Its effect depended on the time interval between thrombin injection and insult. A low dose of thrombin did not induce a major deleterious effect in the acute phase of the infarct development after mild transient ischemia. © 2006 Wiley‐Liss, Inc.
Efficiency of nutrient utilization and reproductive performance of pre‐pubertal anestrous dairy heifers supplemented with inorganic and organic chromium compounds
Authors: Biswas Partha , Haldar Sudipto , Pakhira Manik C , Ghosh Tapan K , Biswas Chinmoy
Published: January 2006

An on‐farm trial was conducted to ascertain the effects of chromium supplementation on the nutrient utilization and reproductive performance of cross‐bred (Bos taurus × Bos indicus) pre‐pubertal anestrous dairy heifers. Chromium was supplemented (0, 0.25, 0.5 and 1.0 mg kg−1 diet dry matter) as chromium chloride hexahydrate or chromium–yeast complex. The intake of the total digestible nutrients (P < 0.01) and body weight gain (P < 0.05) increased with supplementation of chromium. Chromium–yeast supplementation resulted in a dose‐dependent increment (P < 0.01) in the total digestible nutrient intake. Intake and apparent absorption of chromium increased linearly (P < 0.001) with the dose. Chromium chloride tended to be better absorbed (P < 0.10) than the chromium–yeast complex. The source of supplemental chromium did not affect the plasma concentrations of glucose, cholesterol, total protein and albumin. The postprandial plasma glucose concentration in the control group increased by 38% versus 0.27 and 1.1% in the heifers supplemented with 1.0 mg Cr kg−1 dry matter as chromium chloride and chromium–yeast complex, respectively. The postprandial increment in the plasma cholesterol was also generally lower in the supplemented heifers. The plasma chromium concentration varied (P < 0.05) between the groups, although it was difficult to correlate these changes with the sources and doses of supplemental chromium. Chromium chloride and chromium–yeast supplementation resulted in similar changes in the plasma concentrations of copper, zinc, iron and manganese (P > 0.05). Plasma concentrations of copper and zinc, which increased (P < 0.001) with chromium supplementation, declined quadratically (P < 0.05) as the dose of supplemental chromium increased. At the end of the supplementation, two, four and three heifers fed with 0.25, 0.5 and 1.0 mg Cr kg−1 dry matter (as chromium chloride), respectively, developed Graffian follicles and showed estrus; the numbers were one, three and four in the corresponding groups fed with chromium–yeast complex and one, two and three heifers amongst them showed estrus. All the supplemented animals showing estrus conceived and no abortion was reported during the first trimester of their pregnancy. It was concluded that chromium supplementation could appreciably enhance the nutrient utilization and the reproductive performance in anestrous dairy heifers and inorganic trivalent chromium (CrCl3.6H2O) supplementation might be as useful as a chromium–yeast complex for this purpose. Copyright © 2006 Society of Chemical Industry
The effects of travel activities and seasons on expenditure
Authors: Jang SooCheong (Shawn) , Cai Liping A. , Morrison Alastair M. , O'Leary Joseph T.
Published: January 2006

The primary objective of this research was to improve the understanding of the relationships among travel activities, seasons and expenditure after controlling for income. Path analysis was used to test all hypothesised causal relationships. In addition to its conceptual contributions, the findings of the study revealed how international travellers spend during travel in response to changes in activity preferences and season of travel. To maximise travellers' expenditure and to generate greater tourism revenues, destination policy‐makers and marketers need to identify what types of activities and which season contribute most to their destination. Copyright © 2005 John Wiley & Sons, Ltd.
Endorsement advertising in aboriginal tourism: an experiment in Taiwan
Authors: Chang Janet , Wall Geoffrey , Tsai Chen‐Tsang (Simon)
Published: January 2006

Aboriginal cultures have become important tourism attractions worldwide. Cultural villages provide ready access to selected aspects of these cultures in a staged format. They package and promote culture to tourists. Advertising is one component of the promotional mix. Using brochures as the advertising media, the objective of this research is to ascertain the types of advertising endorsers and advertising appeals that are most likely to be successful in attracting visitors to such cultural villages. Adopting an experimental approach, a two‐factor experimental design is manipulated. The causal effect is obtained by using MANOVA and Scheffe tests. The findings are twofold:

the advertising effectiveness of using an aboriginal employee is better than using other types of endorsers;

an emotional advertising appeal elicits a better response than a rational advertising appeal. Copyright © 2005 John Wiley & Sons, Ltd.
Khaosan Road: an evolving backpacker tourist enclave being partially reclaimed by the locals
Authors: Howard Robert W.
Published: January 2006

Backpacker tourist enclaves dot the globe but have been little studied. The present study examined the structure and functioning of Khaosan Road; Bangkok's large archetypal backpacker bubble. It gauged basic dimensions such as tourist area spread, guesthouse and business numbers, and tourist economic and social impact. It surveyed tourist demographics, travel motives, behaviour, and reactions to and uses of the area, and characteristics and reactions of Thai visitors and street vendors. The area is a complex, evolving system with mixed ownership and functions. It is expanding, going up‐market and becoming a key nightlife area for young Thais. Overdevelopment may alter its appeal to backpackers. The data give a detailed picture of one backpacker enclave, which may partly generalise to others. Copyright © 2005 John Wiley & Sons, Ltd.
Kinetics of propane oxydehydrogenation on metals oxides and metals phosphates catalysts: Evidence of compensation effects
Authors: Jibril B. Y.
Published: January 2006

Kinetics of oxidative dehydrogenation of propane has been tested on three groups of catalysts; alumina‐supported metal oxides (MO) (where metal is V, Cr, Ni, Zr, Mo, or Ba), alumina‐supported rare earth metal oxides (RO) (where metal is Ce, Tb, Dy, Ho, Tm, or Yb), and metal phosphates (MP) (where metal is V, Cr, Mn, Ni, Zr, Mg, Ba, or Ce). They were found to be active and exhibited different selectivities to propylene, ethylene, and COx (CO and CO2). The Arrhenius parameters—apparent pre‐exponential factor (lnAapp) and activation energy Eapp)—were evaluated. Evidence of compensation effects was established through statistically significant linear relationship between ln Aapp and Eapp. The rates of propane conversions and COx productions on MO and MP showed common compensation line different from that of RO. When the data for rates of production of propylene and ethylene were plotted, the line for the ethylene rate on MO appeared above that of propylene rate, contrary to the observation on MP and RO. An attempt was made to associate the differences in the behaviors of the catalysts with differences in the ensembles of chemisorbed species that form the respective active centers. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 176–183, 2006
Perception of tactile massage as a complement to other forms of pain relief in rheumatic disease
Authors: Bergsten Ulrika , Petersson Ingemar F. , Arvidsson Barbro
Published: January 2006

Objective. To investigate how patients with rheumatic disease perceive tactile massage as a complement to other pain alleviation methods.

Methods. A phenomenographic approach with semi‐structured interviews was employed on a strategic sample of 14 patients with various rheumatic diseases, both inflammatory and non‐inflammatory, who had been admitted to Spenshult Rheumatic Hospital.

Results. Three descriptive categories with a total of nine conceptions emerged. The descriptive categories were: experiencing alleviation, experiencing trust, and gaining insight. Experiencing alleviation described how patients experience relaxation, pleasure and respite. Experiencing trust described how patients experience a sense of security, confirmation and inner peace. Gaining insight described how patients get to know themselves, see possibilities, and experience wholeness.

Conclusions. When caring for patients who have a chronic illness involving considerable changes to their lives, it is important for health professionals not only to be aware of their physical needs but also to take account of the whole person. This study demonstrates the importance of offering patients a complement to conventional treatment. Tactile massage is a method that promotes a holistic view of patients with chronic pain as well as allowing them to find a new focus in terms of the disease and how they cope with it in their daily lives. Copyright © 2005 John Wiley & Sons, Ltd.
The dominantly inherited motor and sensory neuropathies: Clinical and molecular advances
Authors: Nicholson Garth A.
Published: January 2006

The rapid advances in the molecular genetics and cell biology of hereditary neuropathy have revealed great genetic complexity. It is a challenge for physicians and laboratories to keep pace with new discoveries. Classification of hereditary neuropathies has evolved from a simple clinical to a detailed molecular classification. However, the molecular classification is not simple to use, as different mutations of the same gene produce a range of phenotypes. The logistics of testing for multiple gene mutations are considerable. This review gives a clinical overview of molecular and clinical advances in the dominant hereditary motor and sensory neuropathies [HMSNs, Charcot–Marie–Tooth (CMT) neuropathy], which account for some 60%–70% of families with CMT. The dominant forms of CMT have cellular mechanisms different from those of recessive forms and are a separate diagnostic challenge, so they are not included in this review. Diagnostic testing requires accurate clinical information and a selective approach to gene screening until the cost of multiple gene mutation screening falls. Accurate molecular diagnosis is critical to genetic counseling. This review concentrates on how molecular information can be used clinically, on how physicians can keep pace with new developments, and on the relevance of this new knowledge to patients. Muscle Nerve, 2006
Cutaneous silent period in carpal tunnel syndrome
Authors: Svilpauskaite Jovita , Truffert André , Vaiciene Nerija , Magistris Michel R.
Published: January 2006

The cutaneous silent period (CuSP), a transient suppression of electromyographic activity that follows painful stimuli, allows an indirect study of the small‐diameter A‐δ fibers. To assess the function of these fibers in peripheral nerve disorders, we compared the CuSP of 40 controls to that of 40 patients with carpal tunnel syndrome (CTS) and one patient with a traumatic transection of the median nerve. Patients with CTS were divided into three severity groups, based on electrophysiological data. In CTS, digit 2 evoked CuSP onset latency was increased in all groups, and CuSP duration from abductor digiti minimi was reduced in all groups. In our series, although some parameters of the CuSP were altered, only transection of the nerve abolished it. A‐δ fibers are robust, probably due to their less vulnerable small diameter. This characteristic may be useful to study various conditions and essential for patients to retain some sensation within the median nerve territory. Muscle Nerve, 2006
Reliability and validity of the fine motor scale of the Peabody Developmental Motor Scales–2
Authors: van Hartingsveldt Margo J , Cup Edith HC , Oostendorp Rob AB
Published: January 2006

This study examined the test–retest reliability, inter‐rater reliability, convergent validity and discriminant validity of the Fine Motor Scale of the Peabody Developmental Motor Scales–second edition (PDMS‐FM‐2). Participants included two groups of 18 children between the ages of 4 and 5 years with and without mild fine motor problems. The PDMS‐FM‐2 was administered twice to 12 children and rated by two occupational therapists. The PDMS‐FM‐2 results were compared with scores on the Movement Assessment Battery for Children (M‐ABC). In addition, the scores of the children with and without fine motor problems were compared. For the test–retest reliability and the inter‐rater reliability, correlation coefficients varied from r = 0.84 to r = 0.99. These results suggest that PDMS‐FM‐2 has excellent test–retest and inter‐rater reliability. Convergent validity with the fine motor section of the M‐ABC and discriminant validity have been confirmed. Only 39% of the children in the group with problems in fine motor activities had fine motor problems according to the PDMS‐FM‐2. This finding seems to indicate that the PDMS‐FM‐2 may not be sensitive enough for this population. Copyright © 2005 Whurr Publishers Ltd.
Preparation and characterization of core–shell polystyrene and polymethylsilsesquioxane structure latex particles by seeded polymerization
Authors: Zou Mingxuan , Wang Shijie , Huang Fangzhi , Zhang Zhicheng , Ge Xuewu
Published: January 2006

Composite polystyrene and polymethylsilsesquioxane (PS‐PMSSQ) latices were prepared by hydrolysis and polycondensation of triethoxylmethylsilane (TEOMS) in the presence of PS seed latices, obtained by gamma ray induced polymerization. Morphology of the composite latex particles was observed by transmission electronic microscopy and their size distribution was measured by dynamic laser light scattering. It was found that if 1 wt% silicon‐containing surfactant (SCS) and 0.4 wt% dodecylbenzene sulphonic acid (DBSA) were both used, core–shell/PS‐PMSSQ latex particles could be prepared at 30 °C. The core–shell structure was further characterized by X‐ray photoelectron spectrometry. With 0.5 wt% SCS or 0.2 wt% DBSA, the capsulation was incomplete. At 0 and 90 °C, the PMSSQ phase penetrated into the seed particles. No core–shell structure was observed when DBSA was replaced by hydrochloric acid or SCS was replaced by poly(ethylene glycol) monooctylphenyl ether. Copyright © 2006 Society of Chemical Industry
Photopolymerization of acrylate derivatives initiated by hexaarylbiimidazole with ether groups
Authors: Shi Yongtao , Yin Jie , Kaji Makoto , Yori Hanako
Published: January 2006

A novel hexaarylbiimidazole derivative 2,2′‐bis‐(2‐chlorophenyl)‐4,4′,5,5′‐tetra‐[3‐(2‐hydroxyl‐3‐ethylene glycol monoethylene ether‐propane‐1‐oxy)‐phenyl]‐1,2′‐biimidazole (BCTE‐HABI) was synthesized from 3,3′‐dihydroxyl benzil. Ultraviolet spectra, fluorescence spectra, ESR measurements, photo‐dilatometer experiments and photo‐DSC measurements indicated its good UV‐visible absorption ability, high photolysis efficiency and efficient photo‐initiation for acrylates. Copyright © 2006 Society of Chemical Industry
Synthesis and characterization of urethane vinyl ether crystalline monomers
Authors: Zeng Zhaohua , Yang Jianwen , Pang Laixing , Chen Yonglie
Published: January 2006

UV powder coatings combine the advantages of both conventional thermoset powder coatings and liquid UV‐curing coatings. In this paper, a series of crystalline monomers based on urethane vinyl ether have been synthesized by reaction of hexamethylene diisocyanate (HDI) with hydroxybutyl vinyl ether (HBVE) or together with a saturated alcohol such as 1‐octanol, 2‐butoxy ethanol and 2‐ethoxy ethanol. The crystallinity of the monomers was characterized by DSC, WAXD and polarizing microscopy. It was found that the melting point of the monomer can be expediently adjusted to an adequately low level by changing the type and/or the amount of the saturated alcohol added during the synthesis procedure. Thus, when 20–40 mol% of HBVE was replaced by a saturated alcohol, the melting point decreased to around 75–90 °C, which is suitable for UV‐curing powder coating formulations. Copyright © 2006 Society of Chemical Industry
Study of a potential inhibitor of acetylcholinesterase using UV spectrophotometry, NMR spectroscopy and molecular modeling
Authors: Correia Isabelle , Ronzani Nello , Platzer Nicole , Doan Bich‐Thuy , Beloeil Jean‐Claude
Published: January 2006

1‐[6‐(Acridine‐9‐carbonyloxy)hexyl]pyridinium chloride (1) was synthesized and studied as a potential inhibitor of acetylcholinesterase (AChE), which is frequently involved in Alzheimer's disease. UV spectrophotometry showed that 1 is a reversible and competitive inhibitor of AChE (Ki ≈ 2 × 10−7 M). NMR (TrNOESY) showed that 1, bonded to AChE, maintains an extended form that allows hydrophobic interactions to occur between the aliphatic chain and the deep and narrow gorge of AchE and favors interactions between the acridine group and the catalytic and anionic subsites situated at the bottom of the gorge, and also between the pyridinium ring and the peripheral site. A more detailed picture of the structure of the complex was obtained by combining NMR structural data and molecular modeling (docking, dynamics simulation and energy calculations). Copyright © 2006 John Wiley & Sons, Ltd.
Solvent effect and proton inventory in the hydrolysis of p‐methylphenyl trichloroacetate
Authors: Frasson Cléa M. L. , Brandão Tiago A. S. , Zucco César , Nome Faruk
Published: January 2006

Hydrolysis of p‐methylphenyl trichloroacetate in water–acetonitrile mixtures was studied as a function of water concentration in the range 5.5–55.5 M. The proton inventory technique, in H2O–D2O mixtures, shows, for a value of D atom fraction in the solvent n = 0.5, deviations from the expected value (for a reaction with one proton being transferred) of 7.5 and 12.3%, for experiments in the presence of 16.6 and 33.3 M L2O (L = H or D), respectively. Theoretical treatment of the data obtained at [L2O] = 16.6 M using the Gross–Butler equation are consistent with a cyclic transition‐state structure with three protons involved. Conversely, similar experiments in the presence of [L2O] = 33.3 M show that multiple water molecules are involved in the transition state of the reaction. Copyright © 2006 John Wiley & Sons, Ltd.
Kinetic study on the prooxidative effect of vitamin C on the autoxidation of glycerol trioleate in micelles
Authors: Liu Zai‐Qun
Published: January 2006

Vitamin C (L‐ascorbic acid) protects human health by scavenging toxic free radicals and other reactive oxygen species formed in cell metabolism. The surplus supplementation of vitamin C, however, may be harmful to health because the level of 8‐oxoguanine and 8‐oxoadenine in lymphocyte DNA varies remarkably. In the process of the kinetic investigation on the 2,2′‐azobis(2‐amidinopropane dihydrochloride) (AAPH)‐induced autoxidation of glycerol trioleate (GtH) in the micelles of cetyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and Triton X‐100, the addition of vitamin C accelerates the autoxidation of GtH even in the absence of the free radical initiator, AAPH. The initiating rate, Ri, of vitamin C (VC)‐induced autoxidation of GtH is related to the micelle charge, i.e. Ri = 14.4 × 10−6 [VC] s−1 in SDS (anionic micelle), Ri = 1961 × 10−6 [VC] s−1 in Triton X‐100 (neutral micelle) and Ri is a maximum in CTAB (cationic micelle) when the vitamin C concentration is ∼300 µM. Thus, vitamin C can initiate autoxidation of GtH in micelles, especially in the neutral one. Moreover, the attempt to explore whether α‐tocopherol (TocH) could rectify vitamin C‐induced autoxidation of GtH leads us to find that the rate constant of TocH reacting with the anionic radical of vitamin C (VC.−), k−inh, is ∼103M−1 s−1, which is less than that of the α‐tocopherol radical (Toc.) with vitamin C (kinh = ∼105 M−1 s−1). Thus, the equilibrium constant of the reaction Toc.+VC−⇌TocH+VC.− is prone strongly to the regeneration of Toc. by vitamin C rather than the reverse reaction. Copyright © 2006 John Wiley & Sons, Ltd.
Gradient graft copolymers derived from PEO‐based macromonomers
Authors: Neugebauer Dorota , Zhang Ying , Pakula Tadeusz
Published: January 2006

Atom transfer radical polymerization (ATRP) of two poly(ethylene oxide) (PEO) macromonomers, with different polymerization degrees (DPn) and different end groups, was conducted in solution via the grafting through method. Selection of a PEO methacrylate with a methyl end‐group (PEOMeMA, DPPEO = 23) and a PEO acrylate end‐capped by a phenyl ring (PEOPhA, DPPEO = 4) for the copolymerization led to a spontaneous gradient of PEO grafts along the copolymer backbone. Such a composition was formed because of significantly different reactivities of the two PEO macromonomers. The resulting copolymer has PEOMeMA at one end of the polymer chain, gradually changing through hetero‐sequences of PEOPhA at the other chain end. An increase in the initial feed ratio of PEO acrylate reduced the rate of change in the shape of the gradient. Amorphous–crystalline structure in the copolymers was demonstrated by DSC and WAXS. The mechanical measurements of copolymers consisting of an amorphous PEOPhA and crystallizable PEOMeMA segments indicated elastomeric properties in the range of a soft rubber (G′ ∼ 104 Pa, G′ ≫ G″). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1347–1356, 2006
Spherically propagating thermal polymerization fronts
Authors: Binici Burcu , Fortenberry Dionne I. , Leard Kayce C. , Molden Marcus , Olten Nesrin , Popwell Sam , Pojman John A.
Published: January 2006

We demonstrate for the first time spherically propagating frontal polymerization that also exhibits spin modes. We have developed an interesting system using the amine‐catalyzed Michael addition of a trithiol to a triacrylate to create a rubbery gel. The gel suppresses convection and bubble formation during front propagation. A peroxide is also present to act as a thermal initiator. The front propagates via free‐radical polymerization of the remaining triacrylate after being initiated photochemically in the center of the reactor. It is possible to prepare the rubbery gel in any shape and then initiate thermal frontal polymerization. So‐called spin modes have been observed for the first time in spherically propagating fronts in which waves of polymerization propagate on the expanding spherical front. A system using a diacrylate dissolved in dimethyl sulfoxide with added silica gel and with persulfate as the initiator supports spherical fronts but does not exhibit spin modes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1387–1395, 2006
Integrated surface modification of fully polymeric microfluidic devices using living radical photopolymerization chemistry
Authors: Sebra Robert P. , Anseth Kristi S. , Bowman Christopher N.
Published: January 2006

Surface modification using living radical polymerization (LRP) chemistry is a powerful technique for surface modification of polymeric substrates. This research demonstrates the ability to use LRP as a polymer substrate surface‐modification platform for covalently grafting polymer chains in a spatially and temporally controlled fashion. Specifically, dithiocarbamate functionalities are introduced onto polymer surfaces using tetraethylthiuram disulfide. This technique enables integration of LRP‐based grafting for the development of an integrated, covalent surface‐modification method for microfluidic device construction. The unique photolithographic method enables construction of devices that are not substrate‐limited. To demonstrate the utility of this approach, both controlled fluid flow and cell patterning applications were demonstrated upon modification with various chemical functionalities. Specifically, poly(ethylene glycol) (375) monoacrylate and trifluoroethyl acrylate were grafted to control fluidic flow on a microfluidic device. Before patterning, surface‐functionalized samples were characterized with both goniometric and infrared spectroscopy to ensure that photografting was occurring through pendant dithiocarbamate functionalities. Near‐infrared results demonstrated conversion of grafted monomers when dithiocarbamate‐functionalized surfaces were used, as compared to dormant control surfaces. Furthermore, attenuated total reflectance/infrared spectroscopy results verified the presence of dithiocarbamate functionalities on the substrate surfaces, which were useful in grafting chains of various functionalities whose contact angles ranged from 7 to 86°. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1404–1413, 2006
Novel route to dendritic structures and their application for surface modification
Authors: Reemers Sandra , Mourran Ahmed , Keul Helmut , Möller Martin
Published: January 2006

Monodisperse branched polyurethanes containing long alkyl chains have been prepared by a new convergent synthesis. This synthesis comprises two steps, with hexamethylene diisocyanate uretdione as the starting molecule. The free isocyanate groups of this monomer are reacted with long‐chain alkanols. These diurethane uretdiones are then reacted with amines or amino alcohols under ring opening and the formation of a biuret group. Branching points are not, as usual, part of the monomer but are formed during preparation. The structure of these dendrons has been established with NMR spectroscopy, elemental analysis, mass spectroscopy, and gel permeation chromatography. The dendritic polyurethanes are thermally stable up to 200 °C. Surfaces coated with these materials are hydrophobic. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1372–1386, 2006
Photoresponsive poly(methyl methacrylate)2–(polystyrene)2 miktoarm star copolymer containing an azobenzene moiety at the core
Authors: Erdogan Tuba , Gungor Eda , Durmaz Hakan , Hizal Gurkan , Tunca Umit
Published: January 2006

We prepared a novel miktoarm star copolymer with an azobenzene unit at the core via combination of atom transfer radical polymerization (ATRP) and nitroxide‐mediated free radical polymerization (NMP) routes. For this purpose, first, mikto‐functional initiator, 3, with tertiary bromide (for ATRP) and 2,2,6,6‐tetramethylpiperidin‐1‐yloxy (TEMPO) (for NMP) functionalities and an azobenzene moiety at the core was synthesized. The initiator 3 thus obtained was used in the subsequent living radical polymerization routes such as ATRP of MMA and NMP of St, respectively, to give A2B2 type miktoarm star copolymer, (PMMA)2‐(PSt)2 with an azobenzene unit at the core with controlled molecular weight and low polydispersity (Mw/Mn < 1.15). The photoresponsive properties of 3 and (PMMA)2‐(PSt)2 miktoarm star copolymer were investigated. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1396–1403, 2006
Synthesis, characterization, and properties of new sequenced poly(ether amide)s based on 2‐(4‐aminophenyl)‐5‐aminobenzimidazole and 2‐(3‐aminophenyl)‐5‐aminobenzimidazole
Authors: Ayala Vanesa , Muñoz Dulce M. , Lozano Ángel E. , de la Campa José G. , de Abajo Javier
Published: January 2006

A set of new aromatic poly(ether amide)s containing benzimidazole groups and ethylene oxide sequences of different lengths were synthesized and characterized. The new polymers were prepared from two benzimidazole diamines, 2‐(4‐aminophenyl)‐5‐aminobenzimidazole and 2‐(3‐aminophenyl)‐5‐aminobenzimidazole, and various oligo(ethylene oxide)dibenzoyl chlorides. They exhibited good solubility in polar aprotic solvents and glass‐transition temperatures in the range of 125–300 °C (the longer the ethylene oxide spacer was, the lower the glass‐transition temperature was). The new polyamides were essentially amorphous, as observed by X‐ray diffraction measurements and confirmed by differential scanning calorimetry measurements, by means of which no melting endotherm was observed in any case. The decomposition temperatures, as revealed by thermogravimetric analysis in nitrogen, were about 400 °C for all of them, regardless of the length of the ethylene oxide content or the phenylene ring orientation (meta or para) of the diamine moiety. The number of ethylene oxide linkages per repeat unit also determined the water uptake. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1414–1423, 2006
Syntheses and self‐assembly of poly(benzyl ether)‐b‐poly(N‐isopropylacrylamide) dendritic–linear diblock copolymers
Authors: Ge Zhishen , Luo Shizhong , Liu Shiyong
Published: January 2006

This article describes the syntheses and solution behavior of model amphiphilic dendritic–linear diblock copolymers that self‐assemble in aqueous solutions into micelles with thermoresponsive shells. The investigated materials are constructed of poly(benzyl ether) monodendrons of the second generation ([G‐2]) or third generation ([G‐3]) and linear poly(N‐isopropylacrylamide) (PNIPAM). [G‐2]‐PNIPAM and [G‐3]‐PNIPAM dendritic–linear diblock copolymers have been prepared by reversible addition–fragmentation transfer (RAFT) polymerizations of N‐isopropylacrylamide with a [G‐2]‐ or [G‐3]‐based RAFT agent, respectively. The critical micelle concentration (cmc) of [G‐3]‐PNIPAM220, determined by surface tensiometry, is 6.3 × 10−6 g/mL, whereas [G‐2]‐PNIPAM235 has a cmc of 1.0 × 10−5 g/mL. Transmission electron microscopy results indicate the presence of spherical micelles in aqueous solutions. The thermoresponsive conformational changes of PNIPAM chains located at the shell of the dendritic–linear diblock copolymer micelles have been thoroughly investigated with a combination of dynamic and static laser light scattering and excimer fluorescence. The thermoresponsive collapse of the PNIPAM shell is a two‐stage process; the first one occurs gradually in the temperature range of 20–29 °C, which is much lower than the lower critical solution temperature of linear PNIPAM homopolymer, followed by the second process, in which the main collapse of PNIPAM chains takes place in the narrow temperature range of 29–31 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1357–1371, 2006
Morphology and Patterning Processes of Thin Organosilicon and Perfluorinated Bi‐Layer Plasma Polymer Films
Authors: Wang Xuemei , Grundmeier Guido
Published: January 2006

Summary: An audio‐frequency plasma polymerization set‐up with a planar plasma source was used to deposit thin bi‐layer plasma polymer films using heptadecafluoro‐1‐decene (HDFD) and hexamethyldisiloxane (HMDSO) as monomers. HDFD was used to deposit a thin Teflon‐like plasma polymer film with low surface energy. HMDSO was used to coat this layer with a highly cross‐linked SiCxOyHz film. The growth of the HMDSO plasma polymer illustrates the aspects of island formation at small film thickness (d < 10 nm) as a result of the low surface energy of the HDFD plasma polymer film surface and the buckling‐induced patterning by the compressive stress of the HMDSO plasma polymer film at higher film thickness (d > 10 nm). The film thickness was controlled by quartz crystal microbalance (QCM) and spectroscopic ellipsometry. The chemical structure of the films was measured by means of FT‐IR and XPS. The information about the surface morphology was provided by atomic force microscopy (AFM) measurements.

AFM image (50 × 50 µm2) of anisotropic patterning of bi‐layer plasma polymer films (30 nm HMDSO film on top of a 100 nm HDFD film) on Si wafers at a point defect (dust particle).

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AFM image (50 × 50 µm2) of anisotropic patterning of bi‐layer plasma polymer films (30 nm HMDSO film on top of a 100 nm HDFD film) on Si wafers at a point defect (dust particle).
PECVD of Nanocrystalline Si Layers on High‐Tg Polymer Substrates
Authors: MacQueen Luke A. , Zikovsky Janik , Dennler Gilles , Latreche Mohamed , Czeremuszkin Grzegorz , Wertheimer Michael R.
Published: January 2006

Summary: Hydrogenated nanocrystalline silicon (nc‐Si:H) was deposited by plasma‐enhanced chemical vapor deposition (PECVD) on transparent polymers in order to qualify these for possible use as electronic substrates. As a first step, plasma etch experiments in pure H2 revealed small etch rates for these materials. Thin films of nc‐Si:H were then deposited on samples placed on the grounded electrode of a “Reinberg”‐type parallel plate RF (13.56 MHz) PECVD reactor, at various substrate temperatures (25 °C ≤ Ts ≤ 250 °C), using SiH4 diluted in H2 as the feed‐gas. Thermally induced failure of the nc‐Si:H/polymer composite was avoided within a certain range of deposition conditions, permitting structural and electrical characterization of the deposits.

Temperature‐dependent conductivity, σ(T), for nanocrystalline silicon (nc‐Si:H) films on glass and three polymer substrates, all deposited at Ts = 175 °C.

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Temperature‐dependent conductivity, σ(T), for nanocrystalline silicon (nc‐Si:H) films on glass and three polymer substrates, all deposited at Ts = 175 °C.
Rapid identification of reactivity hazards in a multiuse facility
Authors: Leggett David J.
Published: January 2006

Multiuse pilot‐scale plants often run production campaigns in parallel, requiring frequent changes in the chemistry from campaign to campaign and modified procedures to match the new production needs within a short time span. Facilities must also match clients' product chemistry and process demands with their equipment capabilities.

These campaigns may occur several times a year with considerable overlap of projects. Several basic but important questions arise for the facility manager. For example, how do the facilities' personnel

pay adequate attention to all of the safety issues associated with the chemical reactivity?

ensure that a facility's equipment and the new process chemistry fit together safely, especially with respect to chemical reactivity?

verify emergency relief and vent sizing, estimate cooling duty needs, and implement the necessary process safety changes?

This paper introduces a new approach and procedure that assists plant personnel to assess the process and identify the potential hazards. The procedure also recommends a methodology to evaluate the nature and extent of the hazard. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2006
Carbon nanotube – molecular resonant tunneling diode
Authors: Pandey Rajeev R. , Bruque Nicolas , Alam Khairul , Lake Roger K.
Published: January 2006

Carbon nanotube (CNT) molecular resonant tunnel diodes (RTDs) are proposed to complement bio‐assembled CNT field effect transistors (CNTFETs). A model CNT–pseudopeptide–CNT device is shown to exhibit the current–voltage response of an RTD.

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(© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and properties of InN, InGaN, and InN/InGaN quantum wells
Authors: Naoi H. , Kurouchi M. , Muto D. , Takado S. , Araki T. , Miyajima T. , Na H. , Nanishi and Y.
Published: January 2006

This paper describes our recent progress on InN, In‐rich InxGa1–xN, and InN/InxGa1–xN quantum wells (QWs) grown by radio‐frequency plasma‐assisted molecular‐beam epitaxy. Among the essential growth sequences to obtain high‐quality InN, the nitridation process of (0001) sapphire substrates was reexamined. It was found that the lower‐temperature and longer–period nitridation‐process was very effective in improving crystalline quality of InN films. We succeeded in dramatically improvingc‐axis orientation of InN films without deteriorating theira‐axis orientation by nitridating the substrates at a relatively low‐temperature of 300 °C for a relatively long period of 2 h. The full widths at half maximum (FWHMs) of (0002) X‐ray rocking curves as narrow as 1 arcmin were obtained from only 400 nm thick InN films. These FWHMs are the narrowest value ever reported for InN and moreover approximately a twentieth part of the values obtained from our conventional InN films with a similar thickness, which were grown via the conventional nitridation process carried out at 550 °C for 1 h. Furthermore interference fringes in X‐ray diffraction (ω–2θscan) were observed from these improved InN films. These high crystalline quality InN layers have been employed as a template for the growth of In‐rich InxGa1–xN layers (0.70 ≤x≤ 0.94). The resultant InxGa1–xN layers have shown dramatic improvements in not only the surface morphology but also both thea‐ andc‐axis orientations. By employing In0.8Ga0.2N layers of improved quality as the bottom barrier layer, InN/In0.8Ga0.2N multiple quantum well (MQW) and single quantum well (SQW) structures with different well widths were fabricated. Clear satellite peaks of X‐ray diffraction were observed from these MQW structures. Both of these SQW and MQW structures have exhibited a blue shift of the photoluminescence peak energy with decreasing well width. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Indium Nitride and Indium Rich Related Alloys: Challenges and Opportunities
Authors: Leszczynski M. , Ruterana P. , Stutzmann M. , Wood C.
Published: January 2006

The present issue of physica status solidi (a) contains recent advances in the physics, chemistry and applications of indium nitride. Its goal is to highlight new developments, and to assess the current re‐search status on this important material as well as novel applications that now appear possible. The pa‐pers were submitted to the last European Materials Research Society (E‐MRS) Fall Meeting, held in War‐saw on 5–8 September 2005.

The symposium dealt with the current controversial issues of the bandgap of InN and the composi‐tion fluctuation in InGaN heterostructures. A reasonable agreement seems to be coming up concerning the bandgap. When In nanocrystals can be avoided, the bandgap is converging to the lowest values below 1 eV. However, local measurements like valence electron energy loss spectroscopy still point out a band gap of 1.7 eV. For the InGaN quantum layers, indium composition fluctuation may be present, and the growth conditions could play a critical role.

The quality of the material has dramatically improved since 2000, the MBE grown InN layers have reached residual carrier concentrations in the low 1017 cm–3, and good quality heterostructures are now fabricated (InN/InGaN) by molecular beam epitaxy (MBE).

It was a particular concern of the organisers that the symposium should be in the form of a work‐shop so that enough time is allowed for the discussion of the controversial issues. We hoped that this format would promote a healthy and vigorous exchange of ideas. The lively debate in many of the ses‐sions, and the fact that the final session on Thursday evening was the best attended, suggests that we were at least partly successful in this.

The symposium contained over 60 contributions, both metal organic vapour phase epitaxy and MBE techniques of InN were covered, and special attention was given to the optical and structural quality of the thin films. Thirty invited speakers provided the current status of the research on this exciting mate‐rial. In addition to invited papers, fifteen oral presentations contributed to the eleven sessions ranging from heterostructures growth to band gap issues and devices. Moreover, a poster session, which pre‐sented some twenty interesting reports, provided a further forum for detailed discussions. From those papers that were submitted for publication, 26 were judged, each by two referees, to be highly rated and worthy of publication in physica status solidi (a).

This issue is organised in three sections corresponding to the topical sessions of the Symposium. The first deals with band gap issues, optical and electrical properties, the second with the growth of the InN thin films, whilst the last section is concerned with the structural properties of the layers and de‐vices.
Quantitative electron microscopy of InN–GaN alloys
Authors: Bartel T. , Jinschek J. R. , Freitag B. , Specht P. , Kisielowski C.
Published: January 2006

The local element distribution in quantum wells largely affects physical properties of devices made from such materials. In the past, quantitative electron microscopy was developed to access the stoichiometry on an atomic scale as shown on the cover page of this issue's Editor's Choice [1] for the GaN/InxGa1–xN/GaN and the GaAs/AlxGa1–xAs/GaAs system by the application of QUANTITEM and Chemical Imaging, respectively. In case of GaN/InxGa1–xN/GaN local strain mapping allows for extracting similar data and an unusual large indium fluctuation can be observed if compared with the aluminum distribution in GaAs/AlxGa1–xAs/GaAs quantum well structures. However, radiation damage, sample preparation and microscope stability affect the data analyses and it is of essence to monitor and control such effects as outlined in the related paper.

The first author Til Bartel is a PhD candidate in physics at the Technical University of Berlin, currently visiting LBNL in California to apply transmission electron microscopy to III‐nitride semiconductors. Christian Kisielowski is Staff Scientist and Principle Investigator at the National Center for Electron Microscopy (NCEM) and is responsible for the development and application of high resolution electron microscopy.

The present special issue of physica status solidi (a) is a compilation of presentations from the recent symposium on Indium Nitride and Indium Rich Related Alloys at the E‐MRS 2005 Fall Meeting in Warsaw.