bluuebunny/crossref_metadata_2025 huggingface dataset:
Microwave‐Promoted Esterification Reactions: Optimization and Scale‐Up
Authors: Amore Kristen M. , Leadbeater Nicholas E.
Published: February 2007

Microwave heating is becoming a widely accepted tool for synthetic chemists. While many reactions have been performed on a small scale using microwave heating, few have been further developed into larger‐scale syntheses. Here, a microwave‐promoted esterification reaction protocol is presented. The apparatus used allows for the removal of water generated during the course of the reaction and as a result the process can be driven toward completion. Reactions have been run on scales up to 3 mol.

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CpG site hypermethylation of E‐cadherin and Connexin26 genes in hepatocellular carcinomas induced by a choline‐deficient L‐Amino Acid‐defined diet in rats
Authors: Tsujiuchi Toshifumi , Shimizu Kyoko , Itsuzaki Yumi , Onishi Mariko , Sugata Eriko , Fujii Hiromasa , Honoki Kanya
Published: February 2007

We investigated DNA methylation patterns of E‐cadherin and Connexin26 (Cx26) genes in rat hepatocellular carcinomas (HCCs) induced by a choline‐deficient L‐Amino Acid‐defined (CDAA) diet. Six‐wks‐old F344 male rats were continuously fed with a CDAA diet for 75 wks, and were then killed. A total of five HCCs were obtained, and genomic DNA was extracted from each HCC for assessment of methylation status in the 5′ upstream regions of E‐cadherin and Cx26 genes by bisulfite sequencing, comparing to two normal liver tissues. The five HCCs showed highly methylated E‐cadherin and Cx26 genes, while these genes in two normal liver tissues were all unmethylated. For analysis of gene expression, real‐time quantitative reverse transcription (RT)‐polymerase chain reaction (PCR) was performed. Expressions of E‐cadherin and Cx26 genes were significantly reduced in the five HCCs (P < 0.0001 and P < 0.001, respectively) compared to normal liver tissues, correlating with their methylation statuses. These results suggested that hypermethylation of E‐cadherin and Cx26 genes may be involved in the development of HCCs induced by a CDAA diet in rats. © 2007 Wiley‐Liss, Inc.
Involvement of Ras/Raf‐1/ERK actions in the magnolol‐induced upregulation of p21 and cell‐cycle arrest in colon cancer cells
Authors: Hsu Yi‐Fan , Lee Tong‐Sheng , Lin Shyr‐Yi , Hsu Sung‐Po , Juan Shu‐Hui , Hsu Yuan‐Hsun , Zhong Wen‐Bin , Lee Wen‐Sen
Published: February 2007

Previously, we showed that magnolol induces cell‐cycle arrest in cultured colon and liver cancer cells through an upregulation of the p21 protein [1]. The aim of this study was to delineate the molecular mechanism underlying this magnolol‐induced increase of p21 protein. Thus our RT‐PCR analysis demonstrated that the mRNA levels of p21 were increased at 1 h after magnolol treatment and sustained for at least 24 h. The p21 promoter activity was also increased by magnolol treatment. Western blot analysis demonstrated that treatment of COLO‐205 cells with magnolol increased the levels of phosphorylation of extracellular signal‐regulated kinase (ERK). Pretreatment of the cells with PD98059 abolished the magnolol‐induced upregulation of p21 protein, suggesting the involvement of an ERK pathway in the magnolol‐induced upregulation of p21 in COLO‐205 cells. Ras inhibitor peptide abolished the magnolol‐induced increase of phosphorylated ERK protein levels, increase of p21 protein, and decrease of thymidine incorporation. Moreover, treatment of COLO‐205 with magnolol increased the phosphorylated Raf‐1 protein (the Ras target molecule). Pretreatment of the cells with Raf‐1 inhibitor reversed the magnolol‐induced decrease in thymidine incorporation. Treatment of the cells with CaM kinase inhibitor, but not protein kinase A (PKA) inhibitor or phosphatidylinosital 3‐kinase (PI3K) inhibitor, abolished the magnolol‐induced activation of ERK and decrease of thymidine incorporation. Taken together, our results suggest that magnolol activates ERK phosphorylation through a Ras/Raf‐1‐mediated pathway. Subsequently, p21 expression is increased, and finally thymidine incorporation is decreased. © 2007 Wiley‐Liss, Inc.
Adenovirus E1A requires c‐Ras for full neoplastic transformation or suppression of differentiation of murine preadipocytes
Authors: Cao J. , Arulanandam R. , Vultur A. , Anagnostopoulou A. , Raptis L.
Published: February 2007

We recently demonstrated that the Adenovirus‐5 E1A gene products (E1A), known E2F activators, can block the differentiation of murine preadipocytes and that differentiation suppression occurs at lower levels than required for full neoplastic transformation. Progressively higher levels were accompanied by apoptosis induction. To examine the role of the cellular Ras protooncogene product (Ras) in E1A function, E1A was expressed in C3H10T½ (10T½)‐derived preadipocytes rendered deficient in Ras activity by transfection with inducible or constitutive antisense ras gene constructs (Ras‐knockdowns). The results showed that, although even low amounts of E1A could block the differentiation of 10T½ preadipocytes with normal Ras levels, even the highest E1A levels were unable to block the differentiation or induce transformation of Ras‐knockdown preadipocytes. Ras downregulation did not affect E2F activation by E1A. Interestingly, our results further demonstrated a dramatic reduction in the levels of the E1A protein itself as differentiation progressed, with a concomitant reduction in E1A's ability to induce apoptosis as a result. These findings suggest for the first time that Ras, although cytoplasmic, is an integral component of the pathway whereby E1A, an oncoprotein believed to have primarily nuclear targets, suppresses differentiation or induces neoplastic conversion of murine preadipocytes. © 2007 Wiley‐Liss, Inc.
2‐amino‐1‐methyl‐6‐phenylimidazo [4,5‐b] pyridine‐induced DNA adducts and genotoxicity in chinese hamster ovary (CHO) cells expressing human CYP1A2 and rapid or slow acetylator N‐acetyltransferase 2
Authors: Metry Kristin J. , Zhao Shuang , Neale Jason R. , Doll Mark A. , States J. Christopher , McGregor W. Glenn , Pierce William M. , Hein David W.
Published: February 2007

Heterocyclic amine carcinogens such as 2‐amino‐1‐methyl‐6‐phenylimidazo [4,5‐b] pyridine (PhIP) are present in diet and cigarette smoke. Bioactivation in humans includes N‐hydroxylation catalyzed by cytochrome P4501A2 possibly followed by O‐acetylation catalyzed by N‐acetyltransferase 2 (NAT2). Nucleotide excision repair‐deficient Chinese hamster ovary (CHO) cells were stably transfected with humanCYP1A2and eitherNAT2*4(rapid acetylator) orNAT2*5B(slow acetylator) alleles. CYP1A2 and NAT2 catalytic activities were undetectable in untransfected CHO cell lines. CYP1A2 catalytic activity levels did not differ significantly (P > 0.05) among theCYP1A2‐transfected cell lines. Cells transfected withNAT2*4had significantly higher levels of N‐acetyltransferase (P = 0.0001) and N‐hydroxy‐PhIP O‐acetyltransferase (P = 0.0170) catalytic activity than cells transfected withNAT2*5B. PhIP caused dose‐dependent decreases in cell survival and significant (P < 0.001) increases in mutagenesis measured at thehypoxanthine phosphoribosyl transferase(hprt) locus in all theCYP1A2‐transfected cell lines. Transfection withNAT2*4orNAT2*5Bdid not further increasehprtmutagenesis. PhIP‐inducedhprtmutant cDNAs were sequenced, and 80% of the mutations were single base substitutions at G:C base pairs. dG‐C8‐PhIP DNA adduct levels were dose‐dependent in the order: untransfected < transfected withCYP1A2 < transfected withCYP1A2andNAT2*5B < transfected withCYP1A2andNAT2*4. Following incubation with 1.2 µM PhIP, DNA adduct levels were significantly (P < 0.05) higher in CHO cells transfected withCYP1A2/NAT2*4versusCYP1A2/NAT2*5B. These results strongly support an activation role for CYP1A2 in PhIP‐induced mutagenesis and DNA damage and suggest a modest effect of human NAT2 and its genetic polymorphism on PhIP DNA adduct levels. © 2007 Wiley‐Liss, Inc.
Radiation‐induced posttranscriptional control of M6P/IGF2r expression in breast cancer cell lines
Authors: Iwamoto Keisuke S. , Barber Chad L.
Published: February 2007

The mannose 6‐phosphate/insulin‐like growth factor 2 receptor (M6P/IGF2r), a member of the IGF axis of growth factors, is a negative regulator of cell growth and a putative tumor suppressor gene. Regulation of M6P/IGF2r levels is critical in breast physiology; low expression is associated with various aspects of breast cancer. We have found that ionizing radiation induces the rapid expression of M6P/IGF2r in a dose‐dependent manner in MCF7 human breast cancer cells. We show that this increase is mediated, at least in part, by a stabilization of M6P/IGF2r transcripts by radiation in both ER positive (MCF7 and T47D) and ER negative (MDA‐MB‐231) breast cancer cell lines. It is probable, therefore, that posttranscriptional dysregulation of M6P/IGF2r is a contributing mechanism in breast cancer development and breast cancer response to therapy. This is a novel find that underscores the importance of posttranscriptional control of radiation‐induced gene expression—a phenomenon that has often been paradigmatically attributed to transcriptional control. © 2007 Wiley‐Liss, Inc.
Aesthetic reconstruction of thumb or finger partial defect with trimmed toe‐flap transfer
Authors: Cheng Guoliang , Fang Guangrong , Hou Shujian , Pan Dade , Yuan Guanghai , Wang Zhenjun , Zhang Yunfei , Ding Xiaoheng , Tang Haiping , Yang Zhixian
Published: February 2007

A new concept of esthetic reconstruction for partial loss of distal finger segment was introduced. In a series of 77 patients, 80 thumb or finger partial defects of lateral, dorsal, or volar half, or composite tissue defect of the finger body were reconstructed with lateral skin‐nail flap, dorsal skin‐nail flap, pulp flap, or composite tissue transplant taken from corresponding part of the toes. The blood circulations were reestablished by anastomosing digit arteries of the toe transplants and fingers. Seventy‐eight fingers in 75 patients of this series were successfully reconstructed. The overall survival rate was 97.5%. Follow‐up examinations made half to 12 years postoperatively showed normal length, outward appearance, and function of the reconstructed digits. Their nails are preserved or reconstructed. The pulps are full. Sweating is present. 2‐PD was 4−6 mm. Esthetic reconstruction can achieve the goal of mending any part of tissue loss precisely with good result. © 2007 Wiley‐Liss, Inc. Microsurgery, 2007.
Free functional muscle transfer failure and thrombophilic gene mutations as a potential risk factor: A case report
Authors: Vekris Marios D. , Ovrenovits Maria , Dova Lefkothea , Beris Alexandros E. , Soucacos Panayiotis N. , Kolaitis Nikolaos , Vartholomatos George
Published: February 2007

The evolution of microsurgery popularized the free functioning muscle transfers as secondary procedures to reanimate paralyzed extremities after severance of the brachial plexus, especially when the surgeon deals with late cases. Studies considering transplantation, describe thrombophilic factors as a cause of severe complications after transplantation, such as acute or early rejection episodes, delayed graft function, or chronic graft dysfunction. It is the first time that thrombophilia associated with free muscle‐graft rejection is reported. A young man who had two free functional muscle transfers for brachial plexus reconstruction in the same forearm within an interval of 6 months. The free functional muscle transfer was failed in both cases because of vein thrombosis and subsequent arterial clot. The possibility of thrombophilia was investigated and during the genetic investigation it was discovered that he was heterozygous for the mutations of factor V, G1691A‐Leiden, A4070G and homozygous for the MTHFR C677T mutation. © 2007 Wiley‐Liss, Inc. Microsurgery, 2007.
Ankle position and voluntary contraction alter maximal M waves in soleus and tibialis anterior
Authors: Frigon Alain , Carroll Timothy J. , Jones Kelvin E. , Zehr E. Paul , Collins David F.
Published: February 2007

Compound muscle action potentials (CMAPs) recorded using surface electrodes are often used to assess the excitability of neural pathways to skeletal muscle. However, the amplitude of CMAPs can be influenced by changes at the recording site, independent of mechanisms within the central nervous system. We quantified how joint angle and background contraction influenced CMAP amplitude. In seven subjects CMAPs evoked by supramaximal transcutaneous electrical stimulation of motor axons (Mmax) were recorded using surface electrodes from soleus and tibialis anterior (TA) at static positions over the full range of ankle movement at 5° intervals. Across subjects the peak‐to‐peak amplitude of Mmax was 155% and 159% larger at the shortest than longest muscle lengths for soleus and TA, respectively. In five subjects the effect of ankle position and voluntary contraction on M‐wave/H‐reflex recruitment curves was assessed in the soleus. Both ankle position and level of contraction significantly influenced Mmax, Hmax, and the Hmax to Mmax ratio, but there were no interactions between the two parameters. These peripheral changes that influence Mmax will also impact other CMAPs such as submaximal M‐waves, H‐reflexes, and responses to transcranial magnetic stimulation. As such, during experimental studies CMAPs evoked at a given joint angle and contraction level should be normalized to Mmax recorded at similar joint angle and contraction strength. Muscle Nerve, 2007
Sufficient conditions for graphs to be λ′‐optimal and super‐λ′
Authors: Shang Li , Zhang Heping
Published: February 2007

An edge‐cut S of a connected graph G is called a restricted edge‐cut if G‐S contains no isolated vertices. The minimum cardinality of all restricted edge‐cuts is called the restricted edge‐connectivity λ′(G) of G. A graph G is said to be λ′‐optimal if λ′(G) = ξ(G), where ξ(G) is the minimum edge‐degree of G. A graph is said to be super‐λ′ if every minimum restricted edge‐cut isolates an edge. In this paper, first, we improve and generalize the sufficient conditions for λ′‐optimality in arbitrary graphs, bipartite graphs, and graphs with diameter 2, which were given by Hellwig and Volkmann, and show using examples that our results are best possible. Second, we provide a simple proof with less restrictive conditions than in Hellwig and Volkmann's theorem that gives sufficient conditions for λ′‐optimality in bipartite graphs. We conclude by presenting sufficient conditions for arbitrary, bipartite, and triangle‐free graphs, and for graphs with diameter 2, to be super‐λ′ respectively, and demonstrate that these conditions are best possible. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 49(3), 234–242 2007
A multiscale projection method for macro/microcrack simulations
Authors: Loehnert Stefan , Belytschko Ted
Published: February 2007

We present a new multiscale method for crack simulations. This approach is based on a two‐scale decomposition of the displacements and a projection to the coarse scale by using coarse scale test functions. The extended finite element method (XFEM) is used to take into account macrocracks as well as microcracks accurately. The transition of the field variables between the different scales and the role of the microfield in the coarse scale formulation are emphasized. The method is designed so that the fine scale computation can be done independently of the coarse scale computation, which is very efficient and ideal for parallelization. Several examples involving microcracks and macrocracks are given. It is shown that the effect of crack shielding and amplification for crack growth analyses can be captured efficiently. Copyright © 2007 John Wiley & Sons, Ltd.
The radial basis functions method for identifying an unknown parameter in a parabolic equation with overspecified data
Authors: Dehghan Mehdi , Tatari Mehdi
Published: February 2007

Parabolic partial differential equations with overspecified data play a crucial role in applied mathematics and engineering, as they appear in various engineering models. In this work, the radial basis functions method is used for finding an unknown parameter p(t) in the inverse linear parabolic partial differential equation ut = uxx + p(t)u + φ, in [0,1] × (0,T], where u is unknown while the initial condition and boundary conditions are given. Also an additional condition ∫01k(x)u(x,t)dx = E(t), 0 ≤ t ≤ T, for known functions E(t), k(x), is given as the integral overspecification over the spatial domain. The main approach is using the radial basis functions method. In this technique the exact solution is found without any mesh generation on the domain of the problem. We also discuss on the case that the overspecified condition is in the form ∫0s(t) u(x,t)dx = E(t), 0 < t ≤ T, 0 < s(t) < 1, where s and E are known functions. Some illustrative examples are presented to show efficiency of the proposed method. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
Double Sobolev gradient preconditioning for nonlinear elliptic problems
Authors: Axelsson O. , Karátson J.
Published: February 2007

A mixed variable formulation of a second‐order nonlinear diffusion problem leads to a finite element matrix in a product form. This form enables the efficient updating of the nonlinearity in a Picard type iteration method, in which the preconditioner involves twice a discrete Laplacian. The article gives a conditioning analysis of this method, based on analytic investigations in the corresponding Sobolev function space that reveal the behaviour of this preconditioning. The further generalization of the preconditioner can produce arbitrarily low condition numbers by proper subdivisions of Ω, while still no differentiability of the nonlinear diffusion coefficient is required. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
The upwind finite difference fractional steps method for nonlinear coupled systems
Authors: Yuan Yirang
Published: February 2007

For nonlinear coupled system of multilayer dynamics of fluids in porous media, a second‐order upwind finite‐difference fractional‐steps scheme applicable to parallel arithmetic are put forward, and two‐ and three‐dimensional schemes are used to form a complete set. Some techniques, such as calculus of variations, multiplicative commutation rule of difference operators, decomposition of high‐order difference operators, and prior estimates are adopted. Optimal order estimates in l2 norm are derived to determine the error in the approximate solution. This method has already been applied to the numerical simulation of migration‐accumulation of oil resources. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
The use of cubic B‐spline scaling functions for solving the one‐dimensional hyperbolic equation with a nonlocal conservation condition
Authors: Dehghan Mehdi , Lakestani Mehrdad
Published: February 2007

Problems for parabolic partial differential equations with nonlocal boundary conditions have been studied in many articles, but boundary value problems for hyperbolic partial differential equations have so far remained nearly uninvestigated. In this article a numerical technique is presented for the solution of a nonclassical problem for the one‐dimensional wave equation. This method uses the cubic B‐spline scaling functions. Some numerical results are reported to support our study. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
Exact integration formulas for the finite volume element method on simplicial meshes
Authors: Voitovich T.V. , Vandewalle S.
Published: February 2007

This article considers the technological aspects of the finite volume element method for the numerical solution of partial differential equations on simplicial grids in two and three dimensions. We derive new classes of integration formulas for the exact integration of generic monomials of barycentric coordinates over different types of fundamental shapes corresponding to a barycentric dual mesh. These integration formulas constitute an essential component for the development of high‐order accurate finite volume element schemes. Numerical examples are presented that illustrate the validity of the technology. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
An almost L‐stable BDF‐type method for the numerical solution of stiff ODEs arising from the method of lines
Authors: Ramos Higinio , Vigo‐Aguiar Jesús
Published: February 2007

A new BDF‐type scheme is proposed for the numerical integration of the system of ordinary differential equations that arises in the Method of Lines solution of time‐dependent partial differential equations. This system is usually stiff, so it is desirable for the numerical method to solve it to have good properties concerning stability. The method proposed in this article is almost L‐stable and of algebraic order three. Numerical experiments illustrate the performance of the new method on different stiff systems of ODEs after discretizing in the space variable some PDE problems. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
A mixed finite volume method for elliptic problems
Authors: Mishev Ilya D. , Chen Qian‐Yong
Published: February 2007

We derive a novel finite volume method for the elliptic equation, using the framework of mixed finite element methods to discretize the pressure and velocities on two different grids (covolumes), triangular (tetrahedral) mesh and control volume mesh. The new discretization is defined for tensor diffusion coefficient and well suited for heterogeneous media. When the control volumes are created by connecting the center of gravity of each triangle to the midpoints of its edges, we show that the discretization is stable and first order accurate for both scalar and vector unknowns. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
A Cartesian‐grid collocation method based on radial‐basis‐function networks for solving PDEs in irregular domains
Authors: Mai‐Duy N. , Tran‐Cong T.
Published: February 2007

This paper reports a new Cartesian‐grid collocation method based on radial‐basis‐function networks (RBFNs) for numerically solving elliptic partial differential equations in irregular domains. The domain of interest is embedded in a Cartesian grid, and the governing equation is discretized by using a collocation approach. The new features here are (a) one‐dimensional integrated RBFNs are employed to represent the variable along each line of the grid, resulting in a significant improvement of computational efficiency, (b) the present method does not require complicated interpolation techniques for the treatment of Dirichlet boundary conditions in order to achieve a high level of accuracy, and (c) normal derivative boundary conditions are imposed by means of integration constants. The method is verified through the solution of second‐ and fourth‐order PDEs; accurate results and fast convergence rates are obtained. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
The Decomposition of some RDX and HMX Based Materials in the One Dimensional Time to Explosion Apparatus. Part 2. Estimating the Violence of the Cook‐Off Event
Authors: Williams Michael Robert , Matei Mariana Violetta
Published: February 2007

Various methods of assessment have been applied to the One Dimensional Time to Explosion (ODTX) apparatus and experiments with the aim of allowing an estimate of the comparative violence of the explosion event to be made. Non‐mechanical methods used were a simple visual inspection, measuring the increase in the void volume of the anvils following an explosion and measuring the velocity of the sound produced by the explosion over 1 metre. Mechanical methods used included monitoring piezo‐electric devices inserted in the frame of the machine and measuring the rotational velocity of a rotating bar placed on the top of the anvils after it had been displaced by the shock wave. This last method, which resembles original Hopkinson Bar experiments, seemed the easiest to apply and analyse, giving relative rankings of violence and the possibility of the calculation of a “detonation” pressure.
Synthesis, Thermal Decomposition and Sensitivity Study of CsDNBF
Authors: Wang Shaozong , Zhang Tonglai , Yang Li , Zhang Jianguo , Sun Yuanhua
Published: February 2007

CsDNBF (cesium 7‐hydroxy‐4,6‐dinitro‐5,7‐dihydrobenzofuroxanide) was synthesized from the sodium salt of DNBF and cesium nitrate. The thermal decomposition process has been investigated and the results show that the solid residues at 240 °C are RCOOCs, CsNCO, RNO2 and CsNO3. The sensitivity results demonstrate that CsDNBF has better properties than KDNBF, which has been widely used.
The Use of Trifluoroacetyl as an N‐ and O‐Protecting Group during the Synthesis of Energetic Compounds containing Nitramine and/or Nitrate Ester Groups
Authors: Bellamy Anthony J. , MacCuish Alistair , Golding Peter , Mahon Mary F.
Published: February 2007

N‐ and O‐Trifluoroacetylation has been used to protect secondary amine groups and hydroxyl groups respectively under nitrolysis/nitration conditions. The trifluoroacetyl protecting group may be readily removed from the nitrated products by solvolysis under mild conditions. The energetic molecules that have been produced by this methodology include 2,6,8,12‐tetranitro‐ and 2,4,6,8,12‐pentanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane, 2‐hydroxymethyl‐2‐methyl‐1,3‐dinitratopropane [2,2‐bis(nitratomethyl)‐propan‐1‐ol] and N‐nitroazetidin‐3‐ol.
Ways to Create Fuels for Stoichiometric Gas‐Generating CHNO‐Compositions with Low Ammonium Nitrate Fraction
Authors: Zyuzin Igor N. , Lempert David B.
Published: February 2007

The investigation is aimed to study the possibility of the creation of new CHNO‐fuels for smokeless stoichiometric gas‐generating compositions for airbag inflators. New fuels must have a rather high content of oxygen (to decrease the ammonium nitrate content) as well as a moderate enthalpy of formation in order to prevent an increase of the combustion temperature and of the amount of toxic gases (CO and nitrogen oxides) in the combustion products. Ways to create such new fuels are examined, mainly by introducing low‐enthalpy oxygen containing groups together with oxidizing groups (such as NO2, ONO2, NNO2) into molecules. For several hypothetic substances, the enthalpy of formation has been calculated, thermal stability has been qualitatively estimated, combustion temperatures of stoichiometric compositions have been calculated, and possible ways of their synthesis have been considered.
A Dynamic Calibration Method for Crusher Gauges Based on Material Testing
Authors: Nyberg Heli , Kuokkala Veli‐Tapani , Rämö Jari , Järviniemi Aulis
Published: February 2007

This paper presents a new dynamic calibration method for crusher pressure gauges used in artillery test firings. The calibration method is based on the measurement of the plastic deformation behavior of the crusher elements in the laboratory completely isolated from test firings and measurements by reference pressure transducers. The validity of the calibration model developed is verified by comparison with the pressure records measured in artillery test firings. It was found that the calibration method developed is also suitable for the high load levels and strain rates present in tank firings.
On the Unreacted Hugoniots of Three Plastic Bonded Explosives
Authors: Milne Alec , Longbottom Aaron , Bourne Neil , Millett Jeremy
Published: February 2007

There is a continuing interest in determining the detonation characteristics of loaded plastic‐bonded explosives (PBXs). Within the UK, the relevant government agencies wish to better understand the response of insensitive high explosives. This has required more detailed investigation of the transit of reaction from the unreacted state to products. The starting condition for shock to detonation transition (SDT), before application of a kinetic scheme to describe reaction, is thus the unreacted Hugoniot for the material. In this work, three PBXs, manufactured by BAE Land Systems, are investigated and modelled. All contain RDX in differing quantities in an HTPB binder. One of them contains aluminium. Two of the materials have the same weight percentage of filler and binder but differ in the grain size distribution entrained. The experimental Hugoniots are presented, and a composite equation of state is derived using an engineering model, and a model based on continuum mixture theory. Both are shown to describe the measurements well. Further applications of the technique are described and future uses are outlined.
Fragment Velocities from Thermobaric Explosives in Metal Cylinders
Authors: Jaansalu Kevin M. , Dunning Michael R. , Andrews William S.
Published: February 2007

Thermobaric explosives (TBXs) have been primarily used for their blast, rather than for their fragmentation, characteristics. This work reports on an investigation, using a flash X‐ray imaging technique, of the ability of TBXs to shatter metal casings and to propel the resulting fragments. Three casing materials were used, AISI 1026 steel, ductile iron, and grey cast iron, while two different TBX compositions were used, with C4 serving as a benchmark. The fracture behavior of the casings, as a function of explosive fill and material characteristics, was as expected. One TBX formulation exhibited a run distance to detonation. The Gurney equation was used to correlate and compare the final fragment velocities. It was found that a larger fraction of the explosive energy was available to propel fragments in these two TBX compositions than a comparable amount of C4. This fraction of energy was influenced by the confinement of the detonation products and the ignition delay of the metal powders. These two factors had a greater influence on the fragment velocities than did material characteristics.
Low‐throughput model design of protein folding inhibitors
Authors: Broglia R.A. , Tiana G. , Sutto L. , Provasi D. , Perelli V.
Published: February 2007

The stabilization energy of proteins in their native conformation is not distributed uniformly among all the amino acids, but is concentrated in few (short) fragments, fragments which play a key role in the folding process and in the stability of the protein. Peptides displaying the same sequence as these key fragments can compete with the formation of the most important native contacts, destabilizing the protein and thus inhibiting its biological activity. We present an essentially automatic method to individuate such peptidic inhibitors based on a low‐throughput screening of the fragments which build the target protein. The efficiency and generality of the method is tested on proteins Src‐SH3, G, CI2, and HIV‐1‐PR with the help of a simplified computational model. In each of the cases studied, we find few peptides displaying strong inhibitory properties, properties which are quite robust with respect to point mutations. The possibility of implementing the method through low‐throughput experimental screening of the target protein is discussed. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Telephone calls reduce mortality
Authors: Schedlbauer Angela
Published: February 2007

Do most of our patients take their medication the way we want them to? The answer is most likely no. After three decades of adherence research we are aware of the scope of the problem, but understand little of its causes and lack reliable methods to improve medicine‐taking by patients.

A recent trial published in the BMJ and reviewed in this issue (see pages 16‐17) is a valuable addition to current adherence research showing that telephone counselling by a pharmacist was able to reduce death rates by 41 per cent. Copyright © 2007 Wiley Interface Ltd
Glaucoma: mode of action and properties of current treatments
Authors: McAllister FRCS James
Published: February 2007

Our Drug review of glaucoma management describes the concept of target intraocular pressures and the properties of the drugs employed in primary open‐angle glaucoma. This is followed by an analysis of prescription data, sources of further information and the Datafile. Copyright © 2006 Wiley Interface Ltd
Electrical properties of CuGaSe2 single crystals and polycrystalline coevaporated thin films
Authors: Amara A. , Rezaiki W. , Ferdi A. , Hendaoui A. , Drici A. , Guerioune M. , Bernède J. C. , Morsli M.
Published: February 2007

CuGaSe2 single crystals were grown by iodine vapour transport method, whereas polycrystalline thin films were obtained by coevaporation technique from three sources. The variation of the hole concentration with temperature of CuGaSe2 single crystal in the high temperature region is interpreted assuming thermal activation in the valence band. The density of states effective mass of the holes is deduced. Acceptor and donor concentrations as well as their compensation ratio are reported. The temperature dependence of the hole mobility in valence band is analysed by taking into account several scattering mechanisms of the charge carriers. To account for the temperature dependant conductivity of polycrystalline CuGaSe2 thin film, grain boundary conduction process was suggested. Quantitative values of the mean potential barrier height at grain boundaries and the standard deviation are reported. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comment on “Transport Properties of Tl5Te3 Single Crystals” [phys. stat. sol. (a) Vol. 191, No. 1, 322–329 (2002)]
Authors: Cankurtaran M. , Çelik H.
Published: February 2007

Recently, Gamal et al. [phys. stat. sol. (a) 191, 322 (2002)] reported the results of electrical conductivity, Hall effect and thermoelectric power (TEP) measurements on Tl5Te3 single crystals. The samples used in the study were p‐type semiconductors. From the experimental data for the temperature dependence of TEP, Gamal et al. determined the values of 1.6 × 10–41 kg and 1.5 × 10–40 kg, respectively, for the effective masses of electrons and holes in p‐type Tl5Te3, which are about ten orders of magnitude smaller than the free electron mass, 9.11 × 10–31 kg. We argue that the anomalously small values obtained for the effective mass of charge carriers in Tl5Te3 have no physical significance. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure‐induced ferroelectric to antiferroelectric phase transformation in porous PZT95/5 ceramics
Authors: Zeng T. , Dong X. L. , He H. L. , Chen X. F. , Yao C. H.
Published: February 2007

The hydrostatic pressure‐induced ferroelectric to antiferroelectric (FE–AFE) phase transformation of PZT95/5 ceramics was investigated as a function of porosity, pore shape and pore size. FE–AFE phase transformations were more diffuse and occurred at lower hydrostatic pressures with increasing porosity. The porous PZT95/5 ceramics with spherical pores exhibited higher transformation pressures than those with irregular pores. Moreover, FE–AFE phase transformations of porous PZT95/5 ceramics with polydisperse irregular pores were more diffuse than those of porous PZT95/5 ceramics with monodisperse irregular pores. The relation between pore structure and hydrostatic pressure‐induced FE–AFE transformation was established according to stress concentration theory. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multipole expansions for numerical orbital products
Authors: Talman James D.
Published: February 2007

The product of two numerically defined atomic angular momentum orbitals at different centers is considered. The product can be expanded about a third center on the line segment joining the two centers. A numerical procedure for evaluating the expansion functions is developed. The application of the expansion to the evaluation of four‐center electron–electron repulsion integrals is discussed. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Multiplex target protein imaging in tissue sections by mass spectrometry – TAMSIM
Authors: Thiery Gwendoline , Shchepinov Mikhail S. , Southern Edwin M. , Audebourg Anne , Audard Virginie , Terris Benoît , Gut Ivo G.
Published: February 2007

Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐MS) is becoming a popular tool for imaging histological sections. Currently, this technology is used to image naturally occurring molecules. Here we report a novel development for multiplex imaging of candidate proteins. Rather than detecting whatever molecules happen to be present and above the detection threshold in the desorption pixel, we attach photocleavable mass tags to antibodies to target proteins. ‘Staining’ of histological sections is carried out similarly to common immunohistochemical procedures with chemiluminescent or fluorescent detection using all antibodies of a multiplex simultaneously. Mass tags with discrete masses are released from their respective antibodies by a laser pulse at 355 nm without added matrix. After scanning, mass spectrometry images are created for the mass of each tag. In contrast to fluorescent tags, mass tags do not exhibit mutual quenching. Sections of healthy human pancreatic tissue were imaged to visualize synaptophysin in neuroendocrine cells, and sections from human lymph node and liver invaded by metastatic melanoma to localize the cancer markers PS100 and HMB45 simultaneously. All these proteins are below the detection threshold of direct MALDI‐MS imaging. This method is termed TAMSIM for TArgeted multiplex Mass Spectrometry IMaging. Copyright © 2007 John Wiley & Sons, Ltd.
A modified peptide mapping strategy for quantifying site‐specific deamidation by electrospray time‐of‐flight mass spectrometry
Authors: Stroop Steven D.
Published: February 2007

A modified peptide mapping strategy using electrospray time‐of‐flight mass spectrometry with high‐performance liquid chromatography (HPLC/MS) provides an improved measure of deamidation by performing proteolytic digestion at low temperature (4°C), low pH (6.0) and in organic solvent (≥10% acetonitrile). HPLC resolution of the native (N) and deamidated (D) peptides is achieved, and the ratio of ion counts is converted into percent deamidation. The percent deamidation is established for a reference lot using a time course of digestion (24–120 h) and extrapolation to time zero. Test samples are compared against the reference lot to quantitate changes in site‐specific deamidation. A recombinant purified protein (antigen A) having a single labile Asn‐Gly site is analyzed using this strategy. The N and D peptides from an endoproteinase Lys C (Lys C) digestion (pH 6, 4°C) resolve to near homogeneity on HPLC which results in equivalent percent deamidation when calculated by either UV or ion counts. Deamidation increases with time and pH of proteolysis. Lys C peptide maps of antigen A and bovine serum albumin (BSA) digested at pH 5–8 are comparable. A Lys C digestion time course of a reference lot of antigen A extrapolates to 18% deamidation of the Asn‐Gly site at time zero. This strategy may be generally applicable to protease–protein combinations for improved accuracy in measuring site‐specific deamidation by peptide mapping LC/MS. Copyright © 2007 John Wiley & Sons, Ltd.
Rapid structural elucidation of composite bacterial hopanoids by atmospheric pressure chemical ionisation liquid chromatography/ion trap mass spectrometry
Authors: Talbot Helen M. , Rohmer Michel , Farrimond Paul
Published: February 2007

Bacteriohopanepolyols (BHPs) are membrane lipids produced by a wide range of eubacteria. Their use, however, as molecular markers of bacterial populations and processes has until recently been hampered by the lack of a suitable rapid method for fingerprinting their composition in complex environmental matrices. New analytical procedures employing ion trap mass spectrometry now allow us to investigate the occurrence of BHPs in diverse biological and environmental samples including bacterial cultures, soils, and recent and ancient sediments. Here, we describe the structural characterisation using atmospheric pressure chemical ionisation liquid chromatography/ion trap mass spectrometry (APCI‐LC/MSn) of a number of previously identified but less commonly occurring BHPs such as adenosylhopane and ribonylhopane. Many of the structures described here have previously only been reported in one or just a small number of cultured organisms having been isolated from large amounts of cellular mass (4–26 g) and identified by nuclear magnetic resonance (NMR) techniques after purification of individual compounds. Now, having established characteristic APCI fragmentation patterns, it is possible to rapidly screen many more bacterial cultures using only small amounts of material (<50 mg) as well as environmental samples for these atypical structures and a rapidly growing suite of novel structures. Copyright © 2007 John Wiley & Sons, Ltd.
Infusion mass spectrometry as a fingerprint to characterize varnishes in oil pictorial artworks
Authors: Peris‐Vicente J. , Garrido‐Medina R. , Simó‐Alfonso E. , Gimeno‐Adelantado J. V. , Doménech‐Carbó M. T.
Published: February 2007

Mass spectrometry methodology to characterize drying oil used as binding media and varnishes in pictorial artworks, prior to conservation or restoration treatment, is proposed. The analytical treatment requires prior basic hydrolysis of the samples to release the fatty acids: caprylic, pelargonic, capric, sebacic, azelaic, suberic, eicosanoic, lauric, mirystic, palmitic, linolenic, linoleic, oleic and stearic, followed by separation from the matrix by a hexane/water extraction. After removing the solvent, the remaining solid is dissolved in potassium hydroxide, propanol and methanol. The mixture is directly infused into a mass spectrometer without any previous derivatization or separation steps. The detector is operated in electrospray negative ion mode and the [MH]− ions of the fatty acids enable identification of the acids. Obtained data for fatty acid ion abundances are analyzed by linear discriminant analysis. The drying oils studied (linseed, poppy seed and walnut) were satisfactorily distinguished. The analytical method shows adequate sensitivity, reproducibility, speed and ease. The proposed methodology has been successfully applied to samples from artistic samples belonging to the Cultural Heritage of Valencia (Spain). Copyright © 2007 John Wiley & Sons, Ltd.
Fractionation factors for stable isotopes of N and O during N2O reduction in soil depend on reaction rate constant
Authors: Vieten Beatrix , Blunier Thomas , Neftel Albrecht , Alewell Christine , Conen Franz
Published: February 2007

Nitrous oxide (N2O) is a major greenhouse gas that is mainly produced but also reduced by microorganisms in soils. We determined factors for N and O isotope fractionation during the reduction of N2O to N2 in soil in a flow‐through incubation experiment. The absolute value of the fractionation factors decreased with increasing reaction rate constant. Reaction rates constants ranged from 1.7 10−4 s−1 to 4.5 10−3 s−1. The minimum, maximum and median of the observed fractionation factors were for N −36.0‰, −1.0‰ and −9.3‰ and for O −74.0‰, −6.9‰ and −26.3‰, respectively. The ratio of O isotope fractionation to N isotope fractionation was 2.4 ± 0.3 and it was independent from the reaction rate constants. This leads us to conclude that fractionation factors are variables while their ratio in this particular reaction might be a constant. Copyright © 2007 John Wiley & Sons, Ltd.
Viral metagenomics
Authors: Delwart Eric L.
Published: February 2007

Characterisation of new viruses is often hindered by difficulties in amplifying them in cell culture, limited antigenic/serological cross‐reactivity or the lack of nucleic acid hybridisation to known viral sequences. Numerous molecular methods have been used to genetically characterise new viruses without prior in vitro replication or the use of virus‐specific reagents. In the recent metagenomic studies viral particles from uncultured environmental and clinical samples have been purified and their nucleic acids randomly amplified prior to subcloning and sequencing. Already known and novel viruses were then identified by comparing their translated sequence to those of viral proteins in public sequence databases. Metagenomic approaches to viral characterisation have been applied to seawater, near shore sediments, faeces, serum, plasma and respiratory secretions and have broadened the range of known viral diversity. Selection of samples with high viral loads, purification of viral particles, removal of cellular nucleic acids, efficient sequence‐independent amplification of viral RNA and DNA, recognisable sequence similarities to known viral sequences and deep sampling of the nucleic acid populations through large scale sequencing can all improve the yield of new viruses. This review lists some of the animal viruses recently identified using sequence‐independent methods, current laboratory and bioinformatics methods, together with their limitations and potential improvements. Viral metagenomic approaches provide novel opportunities to generate an unbiased characterisation of the viral populations in various organisms and environments. Copyright © 2007 John Wiley & Sons, Ltd.
Semicopositive linear complementarity systems
Authors: Shen Jinglai , Pang Jong‐Shi
Published: February 2007

Inspired by the dynamic complementarity problem introduced by Mandelbaum, we define several matrix classes in terms of some integral conditions and discuss their connection with the existing class of strictly semicopositive matrices in linear complementarity theory. Using a time‐stepping approximation scheme, we establish the existence of an integrable solution to a class of index‐one linear complementarity systems (LCSs) involving these matrices, and that such a solution is ‘short‐time’ unique if the initial state belongs to a semiobservable cone defined in the recent paper (IEEE Trans. Autom. Control2007, in press). In contrast to the existing well‐posedness theory for the LCS, our result is based on a well‐known matrix property that has not been used in the LCS literature before. Copyright © 2007 John Wiley & Sons, Ltd.
Phase transition of the minimum degree random multigraph process
Authors: Kang Mihyun , Seierstad Taral Guldahl
Published: February 2007

We study the phase transition of the minimum degree multigraph process. We prove that for a constant hg ≈︁ 0.8607, with probability tending to 1 as n → ∞, the graph consists of small components on O(log n) vertices when the number of edges of a graph generated so far is smaller than hgn, the largest component has order roughly n2/3 when the number of edges added is exactly hgn, and the graph consists of one giant component on Θ(n) vertices and small components on O(log n) vertices when the number of edges added is larger than hgn. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2007
ARXPS investigation of diffusion as a limiting process in the incorporation of adatoms into polystyrene surfaces treated by nitrogen plasmas
Authors: Paynter R. W. , Roy‐Guay D. , Parent G. , Ménard M.
Published: February 2007

Polystyrene films were exposed to nitrogen plasmas for periods up to 4 min. ARXPS measurements revealed the presence of oxygen and nitrogen in the surface because of the plasma treatment. The depth profiles of these adatoms were determined by fitting a Thomas–Windle model profile to the data. As found previously, the best‐fit depth profiles resembled a step function, consistent with case II diffusion. However, the depth of penetration of the adatom species into the polymer surface was not found to vary with plasma duration, which is inconsistent with Case II diffusion, and provides evidence that diffusion processes do not limit the loading of adatom species into the surface during nitrogen plasma treatment. A possible reason for the generation of erroneous step function depth profiles is discussed. Copyright © 2007 John Wiley & Sons, Ltd.