bluuebunny/crossref_metadata_2025 huggingface dataset:
Non‐Inferiority Testing with a Variable Margin
Authors: Zhang Zhiwei
Published: August 2006

There has been growing interest, when comparing an experimental treatment with an active control with respect to a binary outcome, in allowing the non‐inferiority margin to depend on the unknown success rate in the control group. It does not seem universally recognized, however, that the statistical test should appropriately adjust for the uncertainty surrounding the non‐inferiority margin. In this paper, we inspect a naive procedure that treats an “observed margin” as if it were fixed a priori, and explain why it might not be valid. We then derive a class of tests based on the delta method, including the Wald test and the score test, for a smooth margin. An alternative derivation is given for the asymptotic distribution of the likelihood ratio statistic, again for a smooth margin. We discuss the asymptotic behavior of these tests when applied to a piecewise smooth margin. A simple condition on the margin function is given which allows the likelihood ratio test to carry over to a piecewise smooth margin using the same critical value as for a smooth margin. Simulation experiments are conducted, under a smooth margin and a piecewise linear margin, to evaluate the finite‐sample performance of the asymptotic tests studied. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prospective use of electrospun ultra‐fine silicate fibers for bone tissue engineering
Authors: Sakai Shinji , Yamada Yusuke , Yamaguchi Tetsu , Kawakami Koei
Published: August 2006

Electrospinning involves the generation of a jet of viscous solution, and results in the formation of ultra‐fine fibers. Silicate fibers prepared using this technology and via the sol‐gel process were evaluated as scaffolds for bone tissue engineering. We found that human osteoblastic MG63 cells successfully adhered on individual silicate fibers, and proliferated on them. In an apatite‐formation ability study, spherical particles covered the fibers after soaking in simulated body fluid for 7 days. Energy dispersive X‐ray analysis revealed that Ca/P atomic ratio of the particles was similar to that of human bone. In addition, X‐ray diffraction analysis revealed that crystalline structure of the particles agreed with that of apatite. These results suggest that electrospun silicate fibers are a potential candidate for scaffolding material in bone tissue engineering.
Melt electrospinning of poly‐(ethylene glycol‐block‐ϵ‐caprolactone)
Authors: Dalton Paul D. , Lleixà Calvet Júlia , Mourran Ahmed , Klee Doris , Möller Martin
Published: August 2006

Various block copolymers of poly(ethylene glycol) and poly(ϵ‐caprolactone) (PEG‐b‐PCL) with molecular weights between 7000 and 26 900 g/mol were synthesized, and melt electrospun at temperatures between 60°C and 90°C. Two types of fibers were collected, including excellent quality fibers – highly coiled and continuous, with a constant diameter and relatively defect free. Such fibers, termed “solid fibers”, were sufficiently cooled during their path between the spinneret and the collector that the symmetric fiber shape is maintained after landing on the collector. The second type of melt electrospun fiber were poor quality, large diameter fibers, flattened on the collector – termed “molten fibers”. The solid and molten fibers were morphologically distinct from each other as determined from scanning electron microscopy (SEM). Using an SEM imaging method to assess the regional variations of collected electrospun material, we found the spinneret pump rate largely influenced the fiber quality. The polymer flow rate to the spinneret and the molecular weight of PEG‐b‐PCL had the greatest effect on the electrospun fibers collected, with an optimum rate of 0.05–0.1 mL/h for the highest molecular weight copolymers. The lowest molecular weight PEG‐b‐PCL tended to electrospray, while the material collected from higher molecular weight copolymers were conducive to fiber formation. The highest quality fibers were PEG‐b‐PCL block copolymers (22 000 and 26 900 g/mol) melt electrospun at temperatures of 85°C and 90°C, corresponding to shear viscosities of the polymer of between 28.1 and 39.4 Pa.S.
The potential of differential mobility analysis coupled to MS for the study of very large singly and multiply charged proteins and protein complexes in the gas phase
Authors: de la Mora Juan Fernández , Ude Sven , Thomson Bruce A.
Published: August 2006

As previously demonstrated by the technique of gas‐phase electrophoretic mobility molecular analyzer (GEMMA) introduced by Kaufman and colleagues, differential mobility analysis (DMA) of charge‐reduced electrospray ions in the gas phase is a useful complement to MS for studying large proteins and their weakly bound complexes. Several limitations of GEMMA, the solutions for which have the potential to greatly improve its performance, are discussed here, including DMA resolution and transmission. A quantitative theory of charge reduction kinetics for dried multiply charged globular proteins at atmospheric pressures is also presented, showing that the charge reduction time must be carefully chosen to maximize a singly charged ion signal, while avoiding survival of contaminating multiply charged species. Because charge reduction limits the range of masses analyzable by MS, we also consider the potential of a parallel‐plate DMA coupled in series to an MS for DMA‐MS studies without charge reduction.
Application of inkjet printing to tissue engineering
Authors: Boland Thomas , Xu Tao , Damon Brook , Cui Xiaofeng
Published: August 2006

Recent advances in organ printing technology for applications relating to medical interventions and organ replacement are described. Organ printing refers to the placement of various cell types into a soft scaffold fabricated according to a computer‐aided design template using a single device. Computer aided scaffold topology design has recently gained attention as a viable option to achieve function and mass transport requirements within tissue engineering scaffolds. An exciting advance pioneered in our laboratory is that of simultaneous printing of cells and biomaterials, which allows precise placement of cells and proteins within 3‐D hydrogel structures. This advance raises the possibility of spatially controlling not only the scaffold structure, but also the type of tissue that can be grown within the scaffold and the thickness of the tissue as capillaries and vessels could be constructed within the scaffolds. Here we summarize recent advances in printing cells and materials using the same device.
Encapsulation and suspension of hydrophobic liquids via electro‐hydrodynamics
Authors: Díaz Gómez Juan E. , Marín Álvaro G. , Marquez Manuel , Barrero Antonio , Loscertales Ignacio G.
Published: August 2006

There are situations in which bioactive products of interest in biotechnology turn out to be hydrophobic. To reach high uniform levels of such products in water‐based host fluids, such as those existing in many biological environments, one strategy consists on dividing the bioactive product into tiny micrometer (or sub‐micrometer) pieces, since these are much more amenable of being uniformly dispersed and stabilized in the host fluid. On the other hand, if the bioactive product must act at specific locations, these micrometer pieces need to be hold in place, an objective that may be achieved by encapsulating them in mats of fibers. Here we demonstrate how these tasks may be accomplished by resorting to the generation and control of electrified coaxial jets of a hydrophilic liquid surrounding the hydrophobic liquid carrying the bioactive substance. When the process is carried out inside a dielectric liquid, double oil/water/oil and simple oil/water emulsions may be formed. On the other hand, when the process runs in air and a biopolymer is added to the hydrophilic liquid, then non woven mats of beaded nanofibers, encapsulating the bioactive product in the beads, are generated.
Dielectrophoresis based‐cell patterning for tissue engineering
Authors: Lin Ruei‐Zeng , Ho Chen‐Ta , Liu Cheng‐Hsien , Chang Hwan‐You
Published: August 2006

Engineering functional tissues and organs in vitro is considered integral to regenerative medicine. Many recent cell patterning technique developments position cells at a pre‐designated pattern to improve tissue engineering efficiency and quality and to facilitate 3‐D cell‐cell interaction exploration. Among these techniques, dielectrophoresis (DEP)‐based cell patterning advantageously offers speed, ease of operation, low degree of cell damage, and precision. This article reviews recent advances in DEP‐based patterning techniques, including electrode design, suitable buffer and hydrogel, effects of the electric current to cells, combination potential with other techniques, as well as efforts to generate 3‐D tissues.
Unzipping the cuticle of the human hair shaft to obtain micron/nano keratin filaments
Authors: Cao Jinan , Wijaya Ratna , Leroy Frédéric
Published: August 2006

An attempt has been made to obtain intact individual keratin filaments of various levels from micron cortical, micron macrofibril to nano intermediate filament and polypeptide α‐helix from the human hair shaft. The feasibility of this initiative has been largely demonstrated by finding that there is a longitudinal seam/zipper on the cuticle of the human hair shaft, which can be unzipped by certain solvents such as performic acid and urea, allowing one to use an anatomical approach to separate intact individual micron/nano filaments. Micron cortical and macrofibril filaments have been obtained. It is also found that the cortical filaments are twisted together to form a yarn, giving rise to the strength for the hair shaft; and that individual cortical filaments are often 2‐2 paired in a similar structure to the double helix. © 2006 Wiley Periodicals, Inc. Biopolymers 83: 614–618, 2006

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Radiographic method to assess the prevalence of sacral spina bifida occulta
Authors: Albrecht T.L. , Scutter S.D. , Henneberg M.
Published: August 2006

Spina bifida occulta of the sacrum is the most common type of spinal deformity. Many authors have published data on the frequency of spina bifida occulta, with varying results. Some possible reasons for this variability could include the differing methods used to gather data and differing ways of classifying the condition. This study attempts to develop an X‐ray method to study sacral spina bifida occulta in a standardized fashion, using an angulated antero‐posterior technique. This technique is then used to estimate the frequency of sacral spina bifida occulta in an Australian sample. The sacra of 53 cadavers were X‐rayed and the level of closure of the sacral spinal canal recorded. The X‐ray technique was validated by open dissection of six of the cadavers studied and was shown to be accurate to half a sacral segment. No sacra with a completely open sacral canal were found, two sacra (4%) were open from S2 down to S5 and ten sacra (19%) were open from S3 down to S5. The most common condition (43%) recorded was where S4 and S5 only were open. Eighteen cadavers (34%) showed only S5 open, and interestingly, no sacra were recorded as having the dorsal sacral arch completely closed. A study of a larger sample will follow using the validated X‐ray technique. Clin. Anat. 20:170–174, 2007. © 2006 Wiley‐Liss, Inc.
Overview of Multiphase Flow Phenomena in Moving Time‐Averaged Space
Authors: Ueyama K. , Saito M.
Published: August 2006

An overview of multiphase flow phenomena is described on the basis of three relations; a relation between an interaction force and time‐averaged physical quantities, a relation between an interaction force and the surrounding flow field, and a relation between time‐averaged physical quantities and multiphase flow. The three relations used to theoretically derive the parabolic radial distribution of gas holdup for recirculating turbulent flow in a bubble column are in good agreement with experimental data. General applicability of the three relations for a variety of multiphase flows is also discussed.
VOF‐Simulation of the Lift Force for Single Bubbles in a Simple Shear Flow
Authors: Bothe D. , Schmidtke M. , Warnecke H.‐J.
Published: August 2006

Bubbles in shear flows experience a lift force, causing them to migrate sideways while they are rising. This lateral migration is investigated in numerical simulations, which are carried out with an extended version of the highly parallelized code FS3D, employing an advanced Volume‐of‐Fluid method. The movement of single bubbles in linear shear flows is simulated to obtain the magnitude of the lift force – expressed by the lift force coefficient CL – for various bubble diameters and material data. Simulation results are in good agreement with experiments for medium liquid phase viscosities. An investigation of the dynamic pressure on the bubble surface explains why large bubbles migrate in the opposite direction compared to small bubbles.
Synthesis, Multiphase Characterization, and Helicity Control in Chiral DACH‐Linked Oligothiophenes
Authors: Melucci Manuela , Barbarella Giovanna , Gazzano Massimo , Cavallini Massimiliano , Biscarini Fabio , Bongini Alessandro , Piccinelli Fabio , Monari Magda , Bandini Marco , Umani‐Ronchi Achille , Biscarini Paolo
Published: August 2006

A new class of chiral oligothiophenes is described. Mono‐, bi‐, ter‐, and quarterthiophenes have been linked to enantiopure trans‐1,2‐cyclohexanediamine (DACH) via diamino or diimino moieties. The stereochemistry of DACH, the type of linker, and oligothiophene size determine the conformational flexibility of these molecules and consequently their molecular and supramolecular helicity in solution and in the solid state. The case of diaminobis(bithiophene), which inverts helicity and shows chiral amplification in the transition from solution to film, is described in detail. Based on the combined use of circular dichroism in solution and in the solid state, single‐crystal/thin‐film X‐ray diffraction, and polarized optical microscopy, a working mechanism has been proposed to explain this unexpected behavior.
Surgical pathology stage by American Joint Commission on Cancer criteria predicts patient survival after preoperative chemoradiation for localized gastric carcinoma
Authors: Rohatgi Pooja R. , Mansfield Paul F. , Crane Christopher H. , Wu Tsung‐Teh , Sunder Punita K. , Ross William A. , Morris Jeffrey S. , Pisters Peter W. , Feig Barry W. , Gunderson Leonard L. , Ajani Jaffer A.
Published: August 2006

BACKGROUND.

Preoperative chemoradiation for localized gastric cancer can modify baseline stage, as determined by surgical pathology stage. Therefore, the authors hypothesized that surgical pathology stage would be a better prognosticator of overall survival (OS) than baseline stage.

METHODS.

Patient populations were combined from 2 prospectively conducted, preoperative chemoradiation trials that used the same therapeutic strategy. Patients must have had localized gastric adenocarcinoma and were staged extensively, including endoscopic ultrasonography and laparoscopy. Patients had to be fit for surgery medically with a technically resectable cancer. All patients provided written informed consent. Patients first received induction chemotherapy for up to 2 months followed by chemoradiation (45 grays) and an attempted surgery. OS was correlated with pretreatment and posttreatment parameters, including surgical pathology stage according to American Joint Commission on Cancer criteria.

RESULTS.

Of 74 patients who were registered, 69 patients (93%) had undergone surgery. Nineteen patients (26%) had a pathologic complete response (pathCR), and 55 patients (81%) had a curative (R0) resection. None of the pretreatment parameters correlated with OS; however, longer OS correlated with lower pathologic stage (P < .0001), R0 resection (P < .001), clinical response noted prior to surgery (P = .002), pathCR (P = .004), lower pathologic lymph node classification (P = .006), and lower pathologic tumor classification (P = .03). Pathologic stage and R0 resection were independent prognostic factors for OS (multivariate Cox model; both P = .05).

CONCLUSIONS.

When preoperative chemoradiation strategy was employed for gastric cancer, the surgical pathology stage, a reflection of cancer's biologic heterogeneity, was a better prognosticator of OS than the baseline clinical stage. Surgical pathology stage, in this setting, may serve as an intermediate endpoint for Phase II/III trials. Cancer 2006. © 2006 American Cancer Society.
Predictors of outcome in patients undergoing postchemotherapy retroperitoneal lymph node dissection for testicular cancer
Authors: Spiess Philippe E. , Brown Gordon A. , Liu Ping , Tannir Nizar M. , Tu Shi‐Ming , Evans James G. , Czerniak Bogdan , Kamat Ashish M. , Pisters Louis L.
Published: August 2006

BACKGROUND

The management of metastatic nonseminomatous germ cell tumors (NSGCT) frequently consists of systemic chemotherapy followed by retroperitoneal lymph node dissection (PC‐RPLND). The aim of the present study was to evaluate the authors' PC‐RPLND experience and identify predictors of outcome in these patients.

METHODS

Between 1980 and 2003, 236 patients with clinical Stage IIA‐III NSGCT underwent PC‐RPLND. Their medical records were retrospectively reviewed for pertinent clinical and treatment‐related outcomes. The 5‐year disease‐specific and recurrence‐free survival was 85% and 75%, respectively, with the median length of follow‐up after RPLND 45 months (6–250 months).

RESULTS

The median age of patients at diagnosis was 28 years, with all patients receiving systemic chemotherapy (median of 5 cycles) before RPLND. On multivariate analysis, predictors of poorer disease‐specific survival (DSS) included systemic symptoms at presentation (P= .05), elevated pre‐RPLND serum alpha fetoprotein (AFP,P= .006) and β‐human chorionic gonadotropin (HCG,P= .004), postoperative complications (P= .03), and recurrence (P< .0001). Predictors of poorer recurrence‐free survival (RFS) included advanced clinical stage (IIC‐III,P= .001) and presence of viable tumor in the RPLND specimen (P= .03). A pre‐RPLND serum AFP > 9 ng/mL and HCG > 4.1 mIU/mL were found to predict a worse DSS (P= .03 and .03, respectively).

CONCLUSIONS

In patients undergoing PC‐RPLND, preoperative tumor markers and the occurrence of postoperative complications or recurrence are predictive of poorer DSS. Advanced clinical stage and viable tumor in the surgical specimen predict worse RFS. Cancer 2006. © 2006 American Cancer Society.
Lysophosphatidic acid acyltransferase‐β (LPAAT‐β) is highly expressed in advanced ovarian cancer and is associated with aggressive histology and poor survival
Authors: Diefenbach Catherine S.M. , Soslow Robert A. , Iasonos Alexia , Linkov Irina , Hedvat Cyrus , Bonham Lynn , Singer Jack , Barakat Richard R. , Aghajanian Carol , Dupont Jakob
Published: August 2006

BACKGROUND

Lysophosphatidic acid acyltransferase‐β (LPAAT‐β) tumor expression is an emerging prognostic, diagnostic, and therapeutic target in early epithelial ovarian cancer (EOC). The significance of tumor overexpression of LPAAT‐β was investigated in a large number of advanced‐ and early‐stage EOC patients.

METHODS

LPAAT‐β expression was analyzed by immunohistochemistry (IHC) in 158 ovarian tumors, including 68 advanced and 90 low‐stage tumors, representing all grades and histologies (including 33 borderline tumors). In advanced‐stage patients, tissue from multiple sites was evaluated to assess differential expression of LPAAT‐β in local tumor and distant metastases.

RESULTS

LPAAT‐β was overexpressed in 90 (57%) of all 158 ovarian tumors. Forty‐nine (72%) of 68 advanced tumors overexpressed LPAAT‐β. LPAAT‐β was associated with the presence of carcinoma versus borderline histology (67% vs. 18%, P < .0001), high histologic grade [according to the Silverberg Grading Scheme] (Grade 1, 25%; Grade 2, 21%; and Grade 3, 54%; P < .0001), and with papillary‐serous histology. In an analysis of the 125 carcinoma patients, LPAAT‐β increased with but was not significantly associated with advanced clinical stage (P = .1431). LPAAT‐β expression was associated with shortened progression‐free survival (PFS) (5‐year PFS, 32% for LPAAT‐β‐positive vs. 60% for LPAAT‐β‐negative; P = .0318) and decreased overall survival (OS) (5‐year OS, 54% for LPAAT‐β‐positive vs. 74% for LPAAT‐β‐negative; P = .0173).

CONCLUSIONS

LPAAT‐β is highly expressed in advanced ovarian tumors and is associated with aggressive histology and decreased PFS and OS. LPAAT‐β is an intriguing prognostic tool for the identification of high‐risk EOC and a potential target for directed therapy that warrants further study. Cancer 2006. © 2006 American Cancer Society.
Effect of obesity on survival in epithelial ovarian cancer
Authors: Pavelka James C. , Brown Rebecca S. , Karlan Beth Y. , Cass Ilana , Leuchter Ronald S. , Lagasse Leo D. , Li Andrew J.
Published: August 2006

BACKGROUND.

Epidemiologic studies suggest that obese women are more likely to die of ovarian cancer than those of ideal body weight, but it is not known whether increased incidence, comorbidities common to obese women, or altered tumor biology is responsible for this difference. The current study attempted to determine the influence of excess body weight on ovarian cancer survival, disease progression, and clinicopathologic factors.

METHODS.

The records of patients undergoing surgery for epithelial ovarian cancer at Cedars Sinai Medical Center between January 1, 1996 and June 30, 2003 were reviewed for height, weight, age, comorbidities, and treatment‐specific details. Statistical analyses included the Fisher exact test, Kaplan‐Meier survival, and Cox regression analyses.

RESULTS.

In all, 216 patients were identified. Eight percent were underweight (body mass index [BMI] < 18.5), 50% were ideal body weight (18.5 ≤ BMI < 25), 25% were overweight (25 ≤ BMI < 30), and 16% were obese (BMI ≥ 30). Age, comorbidities including coronary artery disease and venous thromboembolism, and rates of optimal surgical cytoreduction were similar among BMI strata. Diabetes and hypertension were more common in obese women. Ten (29%) of the obese patients had International Federation of Gynecology and Obstetrics (FIGO) Stage I disease, compared with 19 (10%) of the patients with BMI < 30 (P = .01). In a subcohort of 149 patients with Stage III or IV disease, a significant trend was identified favoring increased BMI as an independent negative factor for disease‐free (P = .02) and overall (P = .02) survival.

CONCLUSIONS.

Obese patients were more likely to have disease limited to the ovaries. For patients with advanced stage disease, obesity was independently associated with both shorter time to recurrence and shorter overall survival. These findings suggest an effect of excess body weight on tumor biology, and studies are under way to elucidate the molecular and hormonal mechanisms underlying these clinical observations. Cancer 2006. © 2006 American Cancer Society.
Nonequilibrium statistics of a reduced model for energy transfer in waves
Authors: DeVille R. E. Lee , Milewski Paul A. , Pignol Ricardo J. , Tabak Esteban G. , Vanden‐Eijnden Eric
Published: August 2006

We study energy transfer in a “resonant duet”—a resonant quartet where symmetries support a reduced subsystem with only 2 degrees of freedom—where one mode is forced by white noise and the other is damped. We consider a physically motivated family of nonlinear damping forms and investigate their effect on the dynamics of the system. A variety of statistical steady states arise in different parameter regimes, including intermittent bursting phases, states highly constrained by slaving among amplitudes and phases, and Gaussian and non‐Gaussian quasi‐equilibrium regimes. All of this can be understood analytically using asymptotic techniques for stochastic differential equations. © 2006 Wiley Periodicals, Inc.
Linear stability and instability of relativistic Vlasov‐Maxwell systems
Authors: Lin Zhiwu , Strauss Walter
Published: August 2006

We consider the linear stability problem for a symmetric equilibrium of the relativistic Vlasov‐Maxwell (RVM) system. For an equilibrium whose distribution function depends monotonically on the particle energy, we obtain a sharp linear stability criterion. The growing mode is proved to be purely growing, and we get a sharp estimate of the maximal growth rate. In this paper we specifically treat the periodic 1½D case and the 3D whole‐space case with cylindrical symmetry. We explicitly illustrate, using the linear stability criterion in the 1½D case, several stable and unstable examples. © 2006 Wiley Periodicals, Inc.
On a micro‐macro model for polymeric fluids near equilibrium
Authors: Lin Fang‐Hua , Liu Chun , Zhang Ping
Published: August 2006

In this paper, we study a micro‐macro model for polymeric fluid. The system involves coupling between the macroscopic momentum equation and a microscopic evolution equation describing the combined effects of the microscopic potential and thermofluctuation. We employ an energetic variation procedure to explore the relation between the macroscopic transport of the particles and the induced elastic stress due to the microscopic structure. For the initial data not far from the equilibrium, we prove the global existence and uniqueness of classical solutions to the system. © 2006 Wiley Periodicals, Inc.
Development of a steroidogenic factor 1/Cre transgenic mouse line
Authors: Bingham Nathan C. , Verma‐Kurvari Sunita , Parada Luis F. , Parker Keith L.
Published: August 2006

The Cre‐loxP strategy provides an approach to disrupt genes in specific tissues and/or cell types, circumventing lethality associated with global knockouts or secondary effects due to gene inactivation at other sites. A critical component is the development of transgenes that target Cre expression to specific cell types. Here, we describe the use of bacterial artificial chromosome (BAC) transgenesis to target Cre expression to tissues that express steroidogenic factor 1 (SF‐1, officially designated Nr5a1). Consistent with the SF‐1 expression pattern, the SF‐1 BAC directed Cre expression to the somatic cells of the gonads, the adrenal cortex, the anterior pituitary, the spleen, and the ventromedial hypothalamic nucleus. This transgene provides a powerful tool to inactivate genes of interest in these tissues. genesis 44:419–424, 2006. Published 2006 Wiley‐Liss, Inc.
Preparation of ZnO Nanowires in a Neutral Aqueous System: Concentration Effect on the Orientation Attachment Process
Authors: Yang Ming , Pang Guangsheng , Li Jixue , Jiang Linfeng , Feng Shouhua
Published: August 2006

ZnO nanowires with diameters in the range of 10 to 30 nm and lengths of ca. several micrometers are prepared with the use of ZnO nanoparticles as building blocks. The length and diameter of the ZnO nanowires can be controlled by the variation of the concentration of the nanoparticles in the orientation attachment process. A plausible mechanism for the concentration‐controlled orientation attachment process is suggested. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Gold Catalysis: Alkylideneoxazolines and ‐oxazoles from Intramolecular Hydroamination of an Alkyne by a Trichloroacetimidate
Authors: Hashmi A. Stephen K. , Rudolph Matthias , Schymura Stefan , Visus Jorge , Frey Wolfgang
Published: August 2006

Several propargylic trichloroacetimidates have been prepared and their reactions with gold catalysts studied. Only with the propargyl and the 1‐methylpropargyl substituent was a selective cyclization observed; with gold(III) chloride in acetonitrile only the product of a fast hydroamination to 4‐methylene‐4,5‐dihydrooxazoles was obtained, in chloroform the slower subsequent aromatization could not be prevented which delivered the oxazoles after long reaction times. Up to 3333 turnovers could be reached. With gold(I) catalysts in chloroform or dichloromethane selective hydroamination to 4‐methylene‐4,5‐dihydrooxazoles without subsequent aromatization was exclusively observed. The gold(I) catalysts also allowed chemoselective cycloisomerization of N‐propargylcarboxamides to 5‐methylene‐4,5‐dihydrooxazoles. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Reactivity of 1‐Phenoxy‐2,7‐octadiene under Metathesis Conditions
Authors: Damez Céline , Bouquillon Sandrine , Hénin Françoise , Muzart Jacques
Published: August 2006

The metathesis of the internal double bond of 1‐phenoxy‐2,7‐octadiene was found to be mediated by Grubbs catalysts. In the presence of rhenium or tungsten‐based catalysts the reaction was found to afford o‐substituted phenols. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Optimization of capillary array electrophoresis single‐strand conformation polymorphism analysis for routine molecular diagnostics
Authors: Jespersgaard Cathrine , Larsen Lars Allan , Baba Shingo , Kukita Yoji , Tahira Tomoko , Christiansen Michael , Vuust Jens , Hayashi Kenshi , Andersen Paal Skytt
Published: August 2006

Mutation screening is widely used for molecular diagnostics of inherited disorders. Furthermore, it is anticipated that the present and future identification of genetic risk factors for complex disorders will increase the need for high‐throughput mutation screening technologies. Capillary array electrophoresis (CAE) SSCP analysis is a low‐cost, automated method with a high throughput and high reproducibility. Thus, the method fulfills many of the demands to be met for application in routine molecular diagnostics. However, the need for performing the electrophoresis at three temperatures between 18°C and 35°C for achievement of high sensitivity is a disadvantage of the method. Using a panel of 185 mutant samples, we have analyzed the effect of sample purification, sample medium and separation matrix on the sensitivity of CAE‐SSCP analysis to optimize the method for molecular diagnostic use. We observed different effects from sample purification and sample medium at different electrophoresis temperatures, probably reflecting the complex interplay between sequence composition, electrophoresis conditions and sensitivity in SSCP analysis. The effect on assay sensitivity from three different polymers was tested using a single electrophoresis temperature of 27°C. The data suggest that a sensitivity of 98–99% can be obtained using a 10% long chain poly‐N,N‐dimethylacrylamide polymer.
A comparative analysis of bleomycin‐induced incomplete chromosome elements in two mammalian cell lines using a telomeric PNA probe
Authors: Flaqué María C. Díaz , Bianchi Martha S. , Bolzán Alejandro D.
Published: August 2006

Fluorescence in situ hybridization (FISH) with a telomeric peptide nucleic acid probe was employed to analyze the induction of incomplete chromosome elements (ICE; i.e., incomplete chromosomes and terminal fragments) by bleomycin (BLM) in two mammalian cell lines. Chinese hamster embryo cells (CHE cell line, average 2n = 23) and domestic rabbit cells (CPC cell line, average 2n = 44) were treated with 2.5 μg/ml BLM; after 18 hr of incubation, first‐division metaphases were stained with the telomeric probe, and ICE and other unstable chromosomal aberrations were scored. BLM induced ICE, dicentrics, and interstitial acentric fragments in CHE cells, but only ICE in CPC cells. About 50% of the metaphases in BLM‐treated CHE cells contained one or more pairs of ICE, while only 20% of treated CPC cells contained ICE. Almost 100% of the BLM‐induced ICE in both cell lines consisted of pairs formed by an incomplete chromosome and a terminal fragment. Our results confirm that ICE are the most frequent type of unstable chromosomal aberration induced by BLM in mammalian cells. Moreover, the present study shows that an increase in the chromosome number does not necessarily result in an increase in the frequency of BLM‐induced ICE. The results also show that the difference in the chromosomal sensitivity to BLM in CHE and CPC cells is due to differences in the absolute frequency but not in the pattern (i.e., type and proportion) of ICE. Environ. Mol. Mutagen., 2006. © 2006 Wiley‐Liss, Inc.
Focal nodular hyperplasia: Lesion characteristics on state‐of‐the‐art MRI including dynamic gadolinium‐enhanced and superparamagnetic iron‐oxide‐uptake sequences in a prospective study
Authors: Terkivatan Türkan , van den Bos Indra C. , Hussain Shahid M. , Wielopolski Piotr A. , de Man Rob A. , IJzermans Jan N.M.
Published: August 2006

Purpose

To image a cohort of patients with pathology‐proven focal nodular hyperplasia (FNH) to assess which characteristics of state‐of‐the‐art magnetic resonance imaging (MRI) of the liver are the most useful for improving the detection and characterization of FNH.

Materials and Methods

In 14 patients, pathology‐proven FNH (N = 33) were prospectively examined using gadolinium (Gd) and superparamagnetic iron‐oxide (SPIO) contrast media. All lesions were evaluated for signal intensity (SI), fatty infiltration, central scar, mode of enhancement with Gd, and uptake of SPIO. The percentage of dynamic contrast enhancement in the arterial, portal, and delayed phases was assessed. The contrast‐to‐noise ratio (CNR) before and after administration of SPIO contrast was calculated.

Results

The SI of the lesions was low to isointense on T1‐weighted (T1W) images, and intermediate to isointense on T2W images. Fatty infiltration of the lesions was present in 6%. The percentages of enhancement in the liver and lesion were 110%, 115%, and 95%, and 151%, 182%, and 160%, respectively (P < 0.0001). All lesions showed uptake of SPIO with improved conspicuity of the central scar and septa. The CNR values precontrast and post‐Gd/SPIO were significantly different for T1 in‐ and opposed‐phase and black‐blood echo‐planar imaging (BBEPI).

Conclusion

Combining dynamic Gd‐enhanced imaging with T1W and T2W sequences after administration of SPIO facilitates comprehensive evaluation of FNH. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Medial collateral ligament healing in macrophage metalloelastase (MMP‐12)‐deficient mice
Authors: Wright Rick W. , Allen Tracy , El‐Zawawy Hossam B. , Brodt Michael D. , Silva Matthew J. , Gill Corey S. , Sandell Linda J.
Published: August 2006

Medial collateral ligament (MCL) injuries heal by a wound repair scar response controlled by a complex cellular and cytokine environment. Many enzymes participate in wound repair, particularly the matrix metalloproteinases. We hypothesize macrophage metalloelastase (MME/MMP‐12) deficiency results in impaired healing of MCL injury. One hundred fifty MME‐deficient and 150 WT (MME+/+) mice underwent knee MCL transection with the opposite knee as a sham operated control. Mice were sacrificed at 3, 7, 28, 42, and 56 days. At each of the five time points, 15 mice were utilized for biological and 15 were utilized for biomechanical testing. Outcome measures were the presence of macrophages to represent the inflammatory phase of wound healing, collagen synthesis to assay for matrix repair, and biomechanical testing for repair strength. Immunohistochemistry demonstrated significantly fewer macrophages in cut MCLs from MME‐deficient mice versus wild‐type (WT) mice at 3, 7, 28, and 42 days (all p ≤ 0.04). In situ hybridization to Col1a1 mRNA in the MME‐deficient cut MCLs at 7, 28, and 42 day time points showed a decreased level of type I pro‐collagen mRNA compared to the WT cut MCLs (p < 0.05). Biomechanical testing revealed cut ligaments from MME‐deficient mice had significantly lower ultimate force and stiffness compared to cut ligaments from WT mice (p < 0.001), with maximal differences of 40% at 7 days for ultimate force and 28 days for stiffness (p < 0.05 by Tukey post hoc test). We conclude MME is important in the multifactorial cascade of knee MCL injury healing, showing significant differences in both the early inflammatory and in the matrix tissue synthesis phases. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:2106–2113, 2006
Effects of frictional conditions on structural transformation of mesocarbon microbeads
Authors: Cui X. H. , Li S. H. , Jin Y. S. , Fu H. L. , Song H. H.
Published: August 2006

The effects of frictional conditions (temperature, loading, sliding velocity) on the tribological performance of mesocarbon microbeads (MCMB), which were manufactured from selected petroleum asphalts, were investigated on an Optimal SRV tribotester when blended as a special additive in a pentaerythritol baseline. The results of the friction tests showed that enhanced heating, increased loading and rapid sliding were beneficial in decreasing friction coefficient and able to shorten the time before the onset of this decrease. A working definition of frictional intensity was elaborated to elucidate the ease with which the MCMB were tribologically transformed into their more lubricious allotropes. The more severe the applied frictional conditions, the lower the calculated value of the defined frictional intensity. Raman spectroscopic analyses of the worn areas of carbon steel tribosurfaces and calculated values of the microcrystalline planar size of the MCMB tribo‐transformed carbonaceous microcrystallines indicated that the decrease in friction coefficient was related to the structural transformation of MCMB towards highly ordered, carbonaceous allotropes. More rigorous frictional conditions would yield highly ordered structures of carbonaceous microcrystallines of bigger planar sizes. Copyright © 2006 John Wiley & Sons, Ltd.
Redesigning alkylated diphenylamine antioxidants for modern lubricants
Authors: Gatto Vincent J. , Elnagar Hassan Y. , Moehle William E. , Schneller Emily R.
Published: August 2006

This paper describes a new alkylation technology that is very effective at synthesizing structurally different alkylated diphenylamine chemistries relative to those currently available to lubricant formulators. Examples are provided showing how this technology can be used in a practical way to produce a variety of chemically modified nonylated diphenylamine types. One example is also provided illustrating the preparation of a higher molecular weight dodecylated diphenylamine. Engine oil performance data utilizing pressurized differential scanning calorimetry (PDSC), the thermo‐oxidation engine oil simulation test, and a bulk oil oxidation test demonstrate that subtle changes in alkylated diphenylamine chemical composition can result in significant oxidation and deposit control performance enhancements or losses. Examples of similar performance responses in industrial oils are demonstrated utilizing PDSC and the rotating pressure vessel oxidation test. These performance changes are directly related to specific structural changes in the modified products. Copyright © 2006 John Wiley & Sons, Ltd.
Lyotropic Liquid Crystalline Polyamides Containing Aromatic, Heterocyclic Structures: Preparation and Properties
Authors: Liu Pengtao , Wang Jinyan , Liu Cheng , Jian Xigao
Published: August 2006

Summary: A series of novel lyotropic liquid crystalline polyamides derived from 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(4‐(aminophenoxyl)phenyl)]‐phthalazinone (DHPZ‐DA), p‐phenylene diamine (PPD) and terephthaloyl dichloride (TPC) have been successfully synthesized by the low temperature solution polycondensation method. The copolymers obtained with inherent viscosity of ≈1.21 to 3.29 dl · g−1, determined in NMP (1 wt.‐% LiCl) or concentrated H2SO4 at 25 °C, were confirmed to be amorphous by WAXD and differential scanning calorimetry (DSC). Their solubility was improved by the introduction of non‐coplanar, twisted phthalazinone moieties and ether linkages into the main chain with the result that they can be soluble in some polar solvents containing a small amount of LiCl. Their Tgs were all above 310 °C and 10% weight loss temperatures in nitrogen above 500 °C. Most of these polyamides can form an anisotropic phase in concentrated H2SO4, NMP (1 wt.‐% LiCl) and DMAc (1 wt.‐% LiCl) solutions, observed on a polarizing light microscope.

Optical micrograph (×40) of polyamide P‐4060 at 10 wt.‐% in NMP/LiCl (1% w/v) solution at room temperature.

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Optical micrograph (×40) of polyamide P‐4060 at 10 wt.‐% in NMP/LiCl (1% w/v) solution at room temperature.
Living Alternating Copolymerization of a Methylenecyclopropane Derivative with CO to Afford Polyketone with Dihydrophenanthrene‐1,10‐diyl Groups
Authors: Takeuchi Daisuke , Okada Takeshi , Kuwabara Junpei , Osakada Kohtaro
Published: August 2006

Summary: Pd complexes prepared from [PdCl(Me)(L)] (L = N‐ligands) and NaBARF catalyze the alternating copolymerization of 7‐methylenedibenzo[a,c]bicyclo[4.1.0]heptane with CO to produce the polyketone. Pd complexes with substituted 1,10‐phenanthroline ligands produce the polymer with narrow molecular weight distribution. Addition of 4‐tert‐butylstyrene to the growing polymer after consumption of the initially charged monomer, results in polymer growth to afford an AB‐type block copolyketone. A Pd complex with an optically active bisoxazoline ligand produces the optically active polymer with narrow polydispersity. The addition of DBU to a solution of polyketone converts the cis‐fused six‐membered rings into the trans‐fused rings via epimerization of the CH carbon attached to the carbonyl group.

Addition of I to cationic Pd complexes catalyzes the ring‐opening copolymerization of the monomer with CO to produce the polyketone, (C(CH2)C14H10CO)n (II).

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Addition of I to cationic Pd complexes catalyzes the ring‐opening copolymerization of the monomer with CO to produce the polyketone, (C(CH2)C14H10CO)n (II).
A Novel Fabrication Method for Poly(propylene)/Clay Nanocomposites by Continuous Processing
Authors: Kim Do Hoon , Park Jun Uk , Cho Kwang Soo , Ahn Kyung Hyun , Lee Seung Jong
Published: August 2006

Summary: It is well known that poly(propylene)/clay (PP/clay) nanocomposite forms an exfoliated structure when mixed with maleic anhydride‐functionalized polypropylene (MAPP). This can be easily achieved by melt processing, however, the use of functionalized chemicals like MAPP costs a lot preventing its commercial application. Recently, it was reported that the exfoliated structure of PP/clay nanocomposite could be obtained without using any compatibilizer such as MAPP when exposed to the electric field. They could regulate the degree of dispersion and exfoliation by controlling the amount of clay loading, the strength of electric field, the time exposed to the electric field, etc. However, this was accomplished by applying the electric field on a rheometer for a long time. It will be practically attractive if we produce PP/clay nanocomposites via continuous processing like extrusion. A new design concept is required for this purpose. In this study, we present a novel method to continuously produce PP/clay nanocomposites using the electric melt pipe equipped with a twin‐screw extruder. Rheology, XRD, and SEM measurements confirm the formation of nanocomposites. Thermal‐ and dynamic‐mechanical analysis also shows the enhancement of the properties. Though, in this study, only a partial intercalation was achieved through continuous processing, it shows a possibility to produce nanocomposites by this approach. As this is a physical process that can be adapted to the conventional extrusion, the approach suggested in this study may be extended to other polymer/clay nanocomposite systems as well.

Schematic diagram of electric melt pipe equipped with a twin‐screw extruder.

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Schematic diagram of electric melt pipe equipped with a twin‐screw extruder.
The Effect of Silane Coupling Agents on the Viscoelastic Properties of Rubber Biocomposites
Authors: Jacob Maya , Francis Bejoy , Varughese K. T. , Thomas Sabu
Published: August 2006

Summary: This paper deals with the dynamic mechanical study of sisal/oil palm hybrid fiber reinforced natural rubber composites (at frequency 1 Hz) with reference to the role of silane coupling agents. Composites were prepared using sisal and oil palm fibers subjected to chemical modifications with different types of silane coupling agents. The silanes used were Silane F8261 [1,1,2,2‐perfluorooctyl triethoxy silane], Silane A1100 [γ‐aminopropyltriethoxy silane] and Silane A151 [vinyl triethoxy silane]. It was observed that for treated composites, storage modulus and loss modulus increased while the damping property was found to decrease. Maximum E' was exhibited by the composite prepared from fibers treated with silane F8261 and minimum by composites containing fibers treated with silane A151. This was attributed to the reduced moisture absorbing capacity of chemically modified fibers leading to improved wetting. This in turn produced a strong interfacial interface giving rise to a much stiffer composite with higher modulus. Surface characterization of treated and untreated sisal fibers by XPS showed the presence of numerous elements on the surface of the fiber. Scanning electron micrographs of tensile fracture surfaces of treated and untreated composites demonstrated better fiber–matrix bonding for the treated composites.

Scheme of interaction of silanes with cellulosic fibers.

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Scheme of interaction of silanes with cellulosic fibers.
Multi‐Morphological Complex Aggregates Formed from Amphiphilic Poly(ethylene oxide)‐block‐Polydimethylsiloxane‐block‐Poly(ethylene oxide) Triblock Copolymers
Authors: Zhang Yong , Zhang Zhijie , Wang Qian , Xu Caihong , Xie Zemin
Published: August 2006

Summary: Amphiphilic triblock copolymers (PEOx‐b‐PDMSy‐b‐PEOx) with different block lengths were synthesized and multi‐morphological complex crew‐cut, star‐like, and short‐chain aggregates were prepared by self‐assembly of the given copolymers. The morphologies and dimensions of the aggregates can be well controlled by variation of the preparation conditions. TEM, SEM, FFR‐TEM, and LLS studies show the resulting morphologies range from LCMs, unilamellar or multilayer vesicles, LCVs, porous spheres to nanorods.

TEM images of the vesicles formed from PEO‐b‐PDMS‐b‐PEO.

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TEM images of the vesicles formed from PEO‐b‐PDMS‐b‐PEO.
Gold Nanostructures Formed in Ionic Clusters of Perfluorinated Ionomer
Authors: Han Tai‐Hoon , Kim Dong‐Ouk , Lee Youngkwan , Suh Su‐Jeong , Jung Hyun‐Chul , Oh Yong‐Soo , Nam Jae‐Do
Published: August 2006

Summary: Gold nanoparticles and nanorods have been synthesized in the ionic cluster network of Nafion using a liquid‐phase chemical impregnation/reduction process seemingly visualizing the phase‐separated hydrated cluster network of Nafion. The spherical shape of the hydrated clusters is clearly seen by the replicated gold nanoparticles with diameters of 5–6 nm. The gold nanoparticles grow through the Nafion cluster network to form gold nanorods with diameters of 5–6 nm and a characteristic length of 12–15 nm, which compare well to the previously reported small‐angle X‐ray scattering results. Tiny channels between adjacent spherical clusters are also observed, which expand to form a rod structure by a reorganization of ion exchange sites and an elastic deformation of Nafion polymer chains. The gold nanorods become interconnected in a cascadic feature, and a tripod‐shaped nanorod structure is one of the most commonly observed structures of the replicated gold. Although further study should be performed, the synthesized gold may be used to visualize the hydrated cluster and the network structure of Nafion, which could be used as important information in identifying the morphology and ion transport phenomena of Nafion.

Gold nanoparticles and nanorods growing through a hydrated Nafion cluster network.

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Gold nanoparticles and nanorods growing through a hydrated Nafion cluster network.