bluuebunny/crossref_metadata_2025 huggingface dataset:
The superficial temporal artery trunk as a donor vessel in cerebral revascularization: benefits and pitfalls
Authors: Alaraj Ali , Ashley William W. , Charbel Fady T. , Amin-Hanjani Sepideh
Published: February 2008

Object

The superficial temporal artery (STA) is the mainstay of donor vessels for extracranial–intracranial bypass in cerebral revascularization. However, the typically used STA anterior or posterior branch is not always adequate in its flow-carrying capacity. In this report the authors describe the use of the STA trunk at the level of the zygoma as an alternative donor and highlight the benefits and pitfalls of this revascularization option.

Methods

The authors reviewed the cases of 4 patients in whom the STA trunk was used as a donor site for anastomosis of a short interposition vein graft. The graft was implanted into the middle cerebral artery to trap a cartoid aneurysm in 2 patients, and the posterior cerebral artery for vertebrobasilar insufficiency in the other 2. Discrepancies in size between the interposition vein and STA trunk were compensated for by a beveled end-to-end anastomosis or by implanting the STA trunk into the vein graft in an end-to-side fashion.

Results

Intraoperative flow measurements confirmed the significantly higher flow-carrying capacity of the STA trunk (54–100 ml/minute) compared with its branches (10–28 ml/minute). The STA trunk interposition graft has several advantages compared with an interposition graft to the cervical carotid, including a shorter graft and no need for a neck incision. However, in the setting of ruptured aneurysm trapping, with the risk of subsequent vasospasm, it is a poor conduit for endovascular therapies.

Conclusions

The STA trunk is a valuable donor option for cerebral revascularization, but should be avoided in the setting of subarachnoid hemorrhage.
Catalysis of Salicylaldehydes and Two Different CH Acids with Electricity: First Example of an Efficient Multicomponent Approach to the Design of Functionalized Medicinally Privileged 2‐Amino‐4H‐Chromene Scaffold
Authors: Elinson Michail N. , Dorofeev Alexander S. , Miloserdov Fedor M. , Ilovaisky Alexey I. , Feducovich Sergey K. , Belyakov Pavel A. , Nikishin Gennady I.
Published: February 2008

Electrochemically induced multicomponent transformation of salicylaldehydes and two different CH acids in alcohols in an undivided cell in the presence of sodium bromide as an electrolyte results in the efficient and selective formation of diversely functionalized, medicinally privileged 2‐amino‐4H‐chromene scaffolds in 65–86% yields. The developed electrocatalytic system affords the distinction between two CH acids according to their reactivity, and offers an efficient approach to the 2‐amino‐4H‐chromene scaffold with a predefined arrangement of desired substituents. The electrocatalytic multicomponent reaction smoothly proceeds with salicylaldehydes bearing both electron‐donating and electron‐withdrawing groups. Thus, fifteen previously inaccessible, close structural analogues of the tumor antagonists HA14‐1 and MX58151 have been synthesized. The electrocatalytic process was found to be advantageous in terms of selectivity and yields compared to classic chemical base catalysis, and includes a remarkable mechanistic feature that is promising for the further development of 2‐amino‐4H‐chromene chemistry. The application of this convenient electrocatalytic multicomponent method to the formation of medicinally relevant 2‐amino‐4H‐chromenes is also beneficial from the viewpoint of diversity‐oriented large‐scale processes and represents a novel, facile and environmentally benign synthetic concept for multicomponent reaction strategy.
Graft rejection after hematopoietic cell transplantation with nonmyeloablative conditioning
Authors: Masmas Tania N. , Petersen Søren L. , Madsen Hans O. , Ryder Lars P. , Kornblit Brian , Svejgaard Arne , Andersen Pernille , Dickmeiss Ebbe , Vindeløv Lars L.
Published: February 2008

Graft rejection after hematopoietic cell transplantation (HCT) with nonmyeloablative conditioning is a rare but serious clinical problem. Graft rejection and salvage therapy in eight patients in a retrospective analysis of 124 consecutive patients is reported. The patients were conditioned with low‐dose fludarabine and total body irradiation (TBI). The association of pretransplantation risk factors with rejection and the effect of chimerism and graft‐versus‐host disease on rejection were analyzed. Overall survival (OS) and progression free survival (PFS) were compared between patients with and without rejection. Retransplantation was performed with increased TBI conditioning for all patients, and with increased mycophenolate mofetil doses for recipients with HLA‐identical sibling donors. No known pretransplantation risk factors were confirmed in this study. Rejection episodes were unevenly distributed over time. The storage temperature of the apheresis products was identified as a risk factor for rejection. Storage of the apheresis products at 5°C diminished the risk of rejection. Low donor T cell chimerism at Day +14 significantly increased the risk of rejection. Seven patients were retransplanted. All but one engrafted successfully, but with decreased OS and PFS. Two patients received pentostatin infusion prior to donor lymphocyte infusions in unsuccessful attempts at reversing rejection. Storage temperature and donor chimerism had a significant effect on rejection. Following rejection, patients are at greater risk of dying from infections and progression/relapse of their malignancy. Retransplantation is feasible and well tolerated after HCT with nonmyeloablative conditioning and should be performed without delay in patients with imminent and manifest graft rejection. Am. J. Hematol. 2008. © 2008 Wiley‐Liss, Inc.
Identification of inflammatory and proresolving lipid mediators in bone marrow and their lipidomic profiles with ovariectomy and omega‐3 intake
Authors: Poulsen Raewyn C. , Gotlinger Katherine H. , Serhan Charles N. , Kruger Marlena C.
Published: February 2008

Newly described lipoxygenase (LOX)‐generated lipid mediators, that is, resolvins and protectins as well as lipoxins, are both anti‐inflammatory and proresolving. We aimed to determine whether these lipid mediators are present in bone marrow and whether their lipidomic profiles are altered following ovariectomy or dietary supplementation with eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) ethyl esters. Female rats were ovariectomised or sham‐operated. Shams and one ovariectomised group received a diet devoid of omega‐3 long‐chain polyunsaturated fatty acids. The remaining ovariectomised rats received either 0.5 g EPA or DHA ethyl ester/kg body weight/day for 4 months. Bone marrow was analyzed using both GC to determine fatty acid composition and mediator lipidomics by LC/MS/MS profiling for the presence of LOX‐pathway lipid mediators derived from arachidonic acid (AA), EPA, and DHA. LOX‐derived products including lipoxins, resolvin D1, resolvin E1, and protectin D1 were identified in bone marrow by the presence of diagnostic ions in their corresponding MS‐MS spectra. The proportion of AA relative to DHA and of AA‐derived relative to DHA‐derived mediators in bone marrow was higher in ovariectomised compared to sham‐operated rats. DHA or EPA ethyl ester supplementation increased the percentage of DHA and EPA in bone marrow and increased the proportion of LOX mediators biosynthesized from DHA or EPA, respectively. Given the potent bioactivities of the lipoxins, resolvins, and protectins, the presence and changes in profile postovariectomy and with EPA and DHA ethyl ester supplementation may be of interest in bone marrow function and as a potential source of these mediators in vivo. Am. J. Hematol., 2008. © 2008 Wiley‐Liss, Inc.
Polymorphisms of the human platelet alloantigens HPA‐1, HPA‐2, HPA‐3, and HPA‐4 in ischemic stroke
Authors: Saidi Sarra , Mahjoub Touhami , Slamia Lamia B. , Ammou Sofyan B. , Al‐Subaie Abeer M. , Almawi Wassim Y.
Published: February 2008

Polymorphism in human platelet antigen (HPA)‐1 and HPA‐3 (GPIIb/IIIa), HPA‐2 (GPIb/IX), HPA‐4 (GPIIIa), and HPA‐5 (GPIa/IIa) was investigated in 329 stroke patients and 444 matched control subjects. HPA genotyping was done by PCR‐SSP method. Lower HPA‐1a (P< 0.001) and higher HPA‐1b (P< 0.001) allele frequencies were seen in patients than control subjects, and homozygosity for HPA‐1b (P< 0.001) alleles was more prevalent in stroke cases than in controls. The allele and genotype distributions of the other HPA polymorphic variants were similar between cases and controls. Select HPA combined genotypes comprising the 2121 (Pc= 0.008) and 2221 (Pc= 0.018) genotypes, which were positively associated, and the 1111 (Pc< 0.001), which was negatively associated with stroke, thereby conferred a disease susceptibility and protective nature to these genotype combinations. Multivariate analysis confirmed the negative association of the 1111 (P< 0.001) and the positive association of the 2121 (P= 0.017) combined genotypes with stroke, after adjustment for a number of covariates. This is the first evidence demonstrating differential association of the common 4 HPA gene variants and specific HPA genotype combinations with stroke. Am. J. Hematol. 2008. © 2008 Wiley‐Liss, Inc.
Archaeological prospecting at the Double Ditch State Historic Site, North Dakota, USA
Authors: Kvamme Kenneth L.
Published: February 2008

A four‐year programme of remote sensing at the Double Ditch State Historic Site, a fortified earthlodge village in the Great Plains of North Dakota, USA, demonstrates the importance of combined prospecting methods for understanding the multidimensional nature of complex settlements. Aerial survey from a powered parachute acquired high‐resolution digital colour and thermal infrared imagery. The former distinguishes houses, borrow pits and ditches from middens and fill areas by changes in vegetation; the latter does the same through temperature variations that also highlight substantial village deposits and century‐old excavations. Magnetic gradiometry reveals two previously unknown fortification systems that vastly increase the settlement's area and projected population to perhaps 2000 individuals. Vast numbers of food storage pits that supported that population are also indicated. Vertical soundings and area surveys of magnetic susceptibility aid in the understanding of storage pit magnetism and anthropogenic soil mounding and removal. A high‐resolution digital model of topography documents surface expressions caused by ditches, houses, borrow pits and mounds; when combined with overlays of geophysical data understanding of remote sensing responses is improved and relationships between large mounds with village defenses are made clear. Ground‐penetrating radar gives insights into mounded midden interior forms and yields details about house interior components, while electrical resistance results improve definition of middens, other depositional areas, houses and borrow pits. This multisensor remote sensing programme reduced excavation costs by allowing a wide variety of archaeological features of interest to be targeted accurately. Excavations confirmed anomaly identifications and established a chronology that documents late fifteenth century origins to an ultimate abandonment about AD 1782. Copyright © 2008 John Wiley & Sons, Ltd.
Searching for the missing baryons in theWarm‐Hot Intergalactic Medium
Authors: Barcons X.
Published: February 2008

At low redshift (z< 2), almost half of the baryons in the Universe are not found in bound structures like galaxies and clusters and therefore most likely reside in a Warm‐Hot Intergalactic Medium (WHIM), as predicted by simulations. Attempts to detect WHIM filaments at cosmological distances in absorption towards bright background sources have yielded controversial results that I review here. I argue that a secure detection of absorption features by the WHIM is at the limit of the XMM‐Newton capabilities, but feasible. A proper characterisation of the whole WHIM belongs to the realm of future X‐ray missions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Planned and serendipitous surveys with XMM‐Newton
Authors: Watson M.G.
Published: February 2008

This article compares and contrasts the virtues of planned (and normally contiguous) surveys with XMM‐Newton and the XMM‐Newton serendipitous sky survey and discusses various ways in which both the quality and efficiency of contiguous surveys with XMM‐Newton could potentially be improved. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Statistical properties of galaxy clusters
Authors: Böhringer H.
Published: February 2008

Galaxy clusters are important probes to test cosmological models and interesting large‐scale laboratories for astrophysical phenomena. For both applications a precise knowledge of global cluster properties, especially their mass is important. X‐ray observations provide still the best key for the evaluation of cluster properties and the description of cluster structure. X‐ray observable–cluster property scaling relations are thus reviewed and new systematic galaxy cluster structure surveys with representative cluster samples are described. For the future precision testing of cosmological models we also need established cluster scaling relations for redshifts above one. First results and possible future XMM‐Newton large programmes are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Suzaku observations of clusters of galaxies
Authors: Matsushita K. , Suzaku SWG team
Published: February 2008

We review results of Suzaku observations of the intracluster medium of clusters of galaxies whose O, Mg, Si, S and Fe abundances have been measured with good accuracy due to the good energy resolution and low background. Metal massto‐light ratios were derived and we will discuss the origin of the metals. We also review the results of the search for bulk motion and hard X‐ray emission. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
XMM‐Newton and broad iron lines
Authors: Fabian A.C.
Published: February 2008

Iron line emission is common in the X‐ray spectra of accreting black holes. When the line emission is broad or variable then it is likely to originate from close to the black hole. X‐ray irradiation of the accretion flow by the power‐law X‐ray continuum produces the X‐ray ‘reflection’ spectrum which includes the iron line. The shape and variability of the iron lines and reflection can be used as a diagnostic of the radius, velocity and nature of the flow. The inner radius of the dense flow corresponds to the innermost stable circular orbit and thus can be used to determine the spin of the black hole. Studies of broad iron lines and reflection spectra offer much promise for understanding how the inner parts of accretion flows (and outflows) around black holes operate. There remains great potential for XMM‐Newton to continue to make significant progress in this work. The need for high quality spectra and thus for long exposure times is paramount. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Toward an unbiased sample of X‐ray selected normal galaxies outside the local Universe
Authors: Georgakakis A.
Published: February 2008

This paper shows that our understanding of the statistical properties of X‐ray selected normal galaxies (e.g. X‐ray luminosity function) can be significantly improved by combining a wide‐area XMM‐Newton survey with the moderare resolution and high S/N optical spectroscopy of the SDSS. Such a combined dataset has the potential to minimise uncertainties that affect existing normal galaxy samples at X‐rays, such as small number statistics, cosmic variance, AGN contamination and incompleteness at bright X‐ray luminosities. It is demonstrated that a 100 deg2 XMM‐Newton survey in the SDSS area to the limit fX(0.5–2 keV) ≈ 5 × 10–15 erg cm–2 s–1 will detect over 400 X‐ray selected normal galaxies with excellent control over systematic biases, thereby providing tight contraints on the X‐ray luminosity function at z ≈ 0.1. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Supernova remnants, planetary nebulae and superbubbles: Prospects for new XMM‐Newton observations
Authors: Decourchelle A.
Published: February 2008

Important results achieved over the last years on supernova remnants, planetary nebulae and superbubbles are briefly reviewed in the context of X‐ray observations. I intend to review the important open scientific questions in these fields, and the specific contributions that can be made by XMM‐Newton. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Using X‐ray observations to identify the particle acceleration mechanisms in VHE SNRs and “dark” VHE sources
Authors: Pühlhofer G.
Published: February 2008

Very high energy (VHE) γ‐ray observations have proven to be very successful in localizing Galactic acceleration sites of VHE particles. Observations of shell‐type supernova remnants have confirmed that particles are accelerated to VHE energies in supernova blast waves; the interpretation of the γ‐ray data in terms of hadronic or leptonic particle components in these objects relies nevertheless strongly on input from X‐ray observations. The largest identified Galactic VHE source class consists of pulsar wind nebulae, as detected in X‐rays. Many of the remaining VHE sources remain however unidentified until now. With X‐ray observations of these enigmatic “dark” objects one hopes to solve the following questions: What is the astrophysical nature of these sources? Are they predominantly electron or hadron accelerators? And what is their contribution to the overall cosmic ray energy budget? The paper aims to provide an overview over the identification status of the Galactic VHE source population. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
>“Resolving” neutron stars physics and geometry
Authors: Caraveo P.A.
Published: February 2008

The unprecedented harvest of X‐ray photons detected from dozens of isolated neutron stars has made it possible to glimpse at their emission mechanisms as well as at their emission geometry. Rotating hot spot(s), superimposed to the global thermal emission from the neutron star surface, are seen from several objects, allowing to probe the stars' external heating sources. Non‐thermal emission is also seen to vary as the stars rotate. Moreover, absorption features have been detected in the spectra of several objects, allowing to probe (tentatively) the stars' magnetic fields. Spectacular tails, trailing the stars' supersonic motion, trace the boundaries of the relativist winds streaming from the star's magnetosphere. Apart from classical radio pulsar and certified radio‐quiet neutron stars, XMM‐Newton has devoted significant observation time to the enigmatic central compact objects, presumably isolated neutron stars shining at the center of their supernova remnants. Far from showing a unifying behaviour, XMM‐Newton data have unveiled a surprising diversity. Understanding the reason(s) behind such diversity is the challenge for the next decade of X‐ray observations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Open questions on black hole binaries
Authors: Kaaret P.
Published: February 2008

I discuss open questions regarding accreting black holes in binary systems, focusing on two questions: can we measure the spins of black holes and what is the nature of the ultraluminous X‐ray sources. XMM‐Newton could make significant strides in answering these questions and others over the next ten years. I suggest two observational programs designed to help increase our understanding of accreting black holes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
XMM‐Newton: The next decade for cool star research
Authors: Schmitt J.H.M.M.
Published: February 2008

In this article I will highlight selected results from XMM‐Newton observations of stellar coronae, emphasizing the specific XMM‐Newton capabilities in terms of high‐resolution spectroscopy, its long‐look capability and its optical monitor. I will focus on results on “normal”, cool stars and present science areas hitherto largely unexploired by XMM‐Newton. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Results and perspectives of young stellar object long look programs
Authors: Sciortino S.
Published: February 2008

Both Chandra and XMM‐Newton have performed long look programs for studying the YSO physics. I will discuss recent results on the controversial issue of Class 0 YSO X‐ray emission, the observational evidence of magnetic funnels interconnecting the YSO with its circumstellar disk and the Fe 6.4 keV fluorescent line emission and its origin. While recent results of the XMM‐Newton DROXO program challenge the “standard” interpretation of the Fe 6.4 kev line origin as due to photoionized fluorescing disk material, the discovery of X‐ray excited Ne 12.81 μ m line is a clear evidence of the interaction between X‐rays and disk material. Future long look observations with XMM‐Newton are required to clarify the X‐ray effects on YSO disk. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
XMM‐Newton: The next decade
Authors: Schartel N.
Published: February 2008

Some key numbers about the XMM‐Newton users, usage of the mission and the scientific outcome are provided. The background for selecting the topic, the preparation work, the organization and the corresponding committees are briefly described. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
XMM‐Newton operations beyond the 10‐year design lifetime
Authors: Parmar A.N. , Heger D. , Metcalfe L. , Muñoz R. , Schartel N.
Published: February 2008

In preparation for XMM‐Newton operations beyond the 10‐year design lifetime ESA instigated an independent review of all aspects of the mission. Unsurprisingly, the review found that the scientific interest in extending the mission is very high and likely to remain so in the foreseeable future. Most importantly, all the elements of the XMM‐Newton mission were found to be stable and trouble free with sufficient consumables and life‐limited items to allow operations of the mission until at least 2018. The review endorsed the proposal to combine elements of the Flight Control Team with those from INTEGRAL and remove real‐time instrument monitoring from ESAC in order to reduce costs and improve efficiency. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Toward a biobased economy: examples from the UK
Authors: Jenkins Tom
Published: February 2008

The security and cost of fossil reserves and the negative environmental impacts associated with their use are driving the replacement of our current economy, based on fossil reserves, with a new economy, based on renewable biological resources. The emerging bioeconomy offers a sustainable alternative for the production of energy, chemicals, materials and transportation fuels from biorenewable feedstocks. In the bioeconomy, biorefineries will process biomass into a range of value‐added bioproducts. This is analogous to today's oil refineries which produce multiple fuels and products from mineral oil. Worldwide progress in biorefinery development is occurring rapidly with a number of countries providing well‐funded public/private programmes to help ensure development of a competitive bioeconomy. The Bioscience for Business Knowledge Transfer Network (KTN) has highlighted the current lack of a coordinated UK initiative in this area and is establishing a major new industry‐led programme, the Integrated Biorefining Technologies Initiative (IBTI). IBTI is a product development partnership consisting of leading industries working together and with the UK Government to define the research and development and demonstration needs of biorefineries for industrial production. Strategic problem‐solving research will focus on diverse renewable raw material feedstocks and the essential conversion technologies necessary to realize their full economic potential. IBTI will help to underpin UK progress in developing a competitive bioeconomy that will be a key to sustainable industrial progress and economic growth in the coming century. © 2008 Society of Chemical Industry and John Wiley & Sons, Ltd
Triple‐helical peptides: An approach to collagen conformation, stability, and self‐association
Authors: Brodsky Barbara , Thiagarajan Geetha , Madhan Balaraman , Kar Karunakar
Published: February 2008

Peptides have been an integral part of the collagen triple‐helix structure story, and have continued to serve as useful models for biophysical studies and for establishing biologically important sequence‐structure‐function relationships. High resolution structures of triple‐helical peptides have confirmed the basic Ramachandran triple‐helix model and provided new insights into the hydration, hydrogen bonding, and sequence dependent helical parameters in collagen. The dependence of collagen triple‐helix stability on the residues in its (Gly‐X‐Y)n repeating sequence has been investigated by measuring melting temperatures of host‐guest peptides and an on‐line collagen stability calculator is now available. Although the presence of Gly as every third residue is essential for an undistorted structure, interruptions in the repeating (Gly‐X‐Y)n amino acid sequence pattern are found in the triple‐helical domains of all nonfibrillar collagens, and are likely to play a role in collagen binding and degradation. Peptide models indicate that small interruptions can be incorporated into a rod‐like triple‐helix with a highly localized effect, which perturbs hydrogen bonds and places the standard triple‐helices on both ends out of register. In contrast to natural interruptions, missense mutations which replace one Gly in a triple‐helix domain by a larger residue have pathological consequences, and studies on peptides containing such Gly substitutions clarify their effect on conformation, stability, and folding. Recent studies suggest peptides may also be useful in defining the basic principles of collagen self‐association to the supramolecular structures found in tissues. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 345–353, 2008.

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
Roles of β‐turns in protein folding: From peptide models to protein engineering
Authors: Marcelino Anna Marie C. , Gierasch Lila M.
Published: February 2008

Reverse turns are a major class of protein secondary structure; they represent sites of chain reversal and thus sites where the globular character of a protein is created. It has been speculated for many years that turns may nucleate the formation of structure in protein folding, as their propensity to occur will favor the approximation of their flanking regions and their general tendency to be hydrophilic will favor their disposition at the solvent‐accessible surface. Reverse turns are local features, and it is therefore not surprising that their structural properties have been extensively studied using peptide models. In this article, we review research on peptide models of turns to test the hypothesis that the propensities of turns to form in short peptides will relate to the roles of corresponding sequences in protein folding. Turns with significant stability as isolated entities should actively promote the folding of a protein, and by contrast, turn sequences that merely allow the chain to adopt conformations required for chain reversal are predicted to be passive in the folding mechanism. We discuss results of protein engineering studies of the roles of turn residues in folding mechanisms. Factors that correlate with the importance of turns in folding indeed include their intrinsic stability, as well as their topological context and their participation in hydrophobic networks within the protein's structure. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 380–391, 2008.

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
Physiologic mechanisms of sequential products synthesis in 1,3‐propanediol fed‐batch fermentation by Klebsiella pneumoniae
Authors: Zheng Zong‐Ming , Xu Yun‐Zhen , Liu Hong‐Juan , Guo Ni‐Ni , Cai Zhong‐Zhen , Liu De‐Hua
Published: February 2008

The glycerol fed‐batch fermentation by Klebsiella pneumoniae CGMCC 1.6366 exhibited the sequential synthesis of products, including acetate, 1,3‐propanediol (1,3‐PD), 2,3‐butanediol, ethanol, succinate, and lactate. The dominant flux distribution was shifted from acetate formation to 1,3‐PD formation in early‐ exponential growth phase and then to lactate synthesis in late‐exponential growth phase. The underlying physiological mechanism of the above observations has been investigated via the related enzymes, nucleotide, and intermediary metabolites analysis. The carbon flow shift is dictated by the intrinsic physiological state and enzymatic activity regulation. Especially, the internal redox state could serve as a rate‐controlling factor for 1,3‐PD production. The q1,3‐PD formation was the combined outcomes of regulations of glycerol dehydratase activity and internal redox balancing. The qethanol/qacetate ratios demonstrated the flexible adaptation mechanism of K. pneumoniae preferring ATP generation in early‐exponential growth phase. A low PEP to pyruvate ratio corresponded LDH activity increase, leading to lactate accumulation in stationary phase. Biotechnol. Bioeng. 2008;100: 923–932. © 2008 Wiley Periodicals, Inc.
Optimization of sylvite transformation into arcanite using experimental design methodology
Authors: Fezei R. , Hammi H. , M'nif A.
Published: February 2008

This study is an application of the experimental design methodology for optimizing a potassium sulfate synthesis reaction. The latter is a two‐stage reaction through an intermediate product (Schoenite: K2SO4.MgSO4·6H2O). To determine optimal experimental conditions of the first stage, we have conducted a fractional factorial design and a central composite one. The optimal conditions of the second stage were determined only by means of a fractional factorial design. Several physico‐chemical techniques were used to implement this study, namely potentiometry, complexometry, gravimetry and X‐ray diffraction. This work has showed that this double decomposition reaction, when performed under the determined optimal conditions, gives good quality potassium sulfate (purity more than 95%) with a maximal yield. Copyright © 2008 John Wiley & Sons, Ltd.
Resolving the sign ambiguity in the singular value decomposition
Authors: Bro R. , Acar E. , Kolda Tamara G.
Published: February 2008

Many modern data analysis methods involve computing a matrix singular value decomposition (SVD) or eigenvalue decomposition (EVD). Principal component analysis is the time‐honored example, but more recent applications include latent semantic indexing (LSI), hypertext induced topic selection (HITS), clustering, classification, etc. Though the SVD and EVD are well established and can be computed via state‐of‐the‐art algorithms, it is not commonly mentioned that there is an intrinsic sign indeterminacy that can significantly impact the conclusions and interpretations drawn from their results. Here we provide a solution to the sign ambiguity problem and show how it leads to more sensible solutions. Copyright © 2008 John Wiley & Sons, Ltd.
Chemistry of Bridging Phosphanes: CuI Dimers Bearing 2,5‐Bis(2‐pyridyl)phosphole Ligands
Authors: Nohra Brigitte , Rodriguez‐Sanz Elena , Lescop Christophe , Réau Régis
Published: February 2008

Bis(2‐pyridyl)phosphole 1 reacted with CuI sources giving rise to dicationic or neutral dimers 2,3. In these derivatives, 1 acts as a 1κN:1,2κP:2κN donor with a symmetrically bridging P centre. X‐ray diffraction studies of these species revealed no constraint due to the unusual coordination mode of the P donor. A comparative study with a monometallic CuI complex in which 1 acts as a P,N chelate is presented. The acetonitrile ligands of the dicationic complex 2 can be displaced by a variety of donors. Bipyridine (bipy) acts as a chelating donor, while 1,1′‐bis(diphenylphosphino)methane (dppm) and bis(2‐pyridyl)phosphole 1 behave as bridging ligands. By using dppm and 1, the complexes arising from the stepwise displacement of the acetonitrile ligands of complex 2 can be isolated. X‐ray diffraction studies performed on these novel complexes revealed that the P centre can easily switch from a bridging to a semibridging coordination mode. Of particular interest, within the same unit cell, complexes with P centres exhibiting bridging and semibridging coordination modes are observed. This switching can be induced by weak effects such as a different conformation of the incoming ligand. CuI dimers assembled by 1 are air‐stable derivatives that are not water sensitive. Hydrolysis of the PF6− counterion occurs under drastic conditions and results in the formation of a PO2F2 fragment coordinated to a CuI–1 fragment.
Herstellen von Emulsionen in einfachen und modifizierten Lochblenden: Einfluss der Geometrie auf die Effizienz der Zerkleinerung und Folgen für die Maßstabsvergrößerung
Authors: Aguilar F. , Köhler K. , Schubert H. , Schuchmann H. P.
Published: February 2008

Das Hochdruckhomogenisieren ist ein in der Technik weit verbreitetes Homogenisierverfahren. Tropfen einer Rohemulsion („Premix”︁) werden in der Homogenisierdüse aufgrund von Scher‐ oder Dehnspannungen sowie durch Trägheitskräfte vor allem in turbulenter oder in kavitierender Strömung zerkleinert. Die Geometrie der Homogenisierdüse sowie das Stoffsystem bestimmen wie die Tropfen zerkleinert werden (Zerkleinerungsmechanismus) und wie effizient dabei die eingebrachte Energie umgesetzt wird. Die Mechanismen der Zerkleinerung von Öltropfen unterschiedlicher Viskositäten in einfachen (geraden) Lochblenden unterschiedlicher Geometrie sind Inhalt des ersten Teils der im Rahmen dieses Beitrages dargestellten Untersuchungen. Diese Ergebnisse sind auch Basis für eine Maßstabvergrößerung, die durch ein Scale‐ bzw. Numbering up gelöst werden kann. Im zweiten Teil dieses Beitrages werden Ergebnisse zu konstruktiven Begrenzungen einer geometrischen Maßstabsvergrößerung und Randbedingungen für ein Numbering up aufgezeigt.
Indirect Determination of Trace Copper(II) by Adsorptive Stripping Voltammetry with Zincon at a Carbon Paste Electrode
Authors: Taher Mohammad Ali , Esfandyarpour Mohammad , Abbasi Shahryar , Mohadesi Alireza
Published: February 2008

Traces of copper(II) can be determined by adsorptive stripping voltammetry using 2‐carboxy‐2′‐hydroxy‐5′‐sulfoformazyl benzene (Zincon) as complex forming reagent. First in phosphate buffer pH 6.4, copper(II)‐Zincon complex was adsorbed on carbon paste electrode (CPE) with an accumulation potential of 0.6 V. Following this, adsorbed complex was oxidized and detected by differential pulse voltammetric (DPV) scan from 0.6 to 1.0 V. The effective parameters in sensor response were examined. The detection limit (DL) of copper(II) was 1.1 μg/L and relative standard deviations (RSDs) for 10 and 200 μg/L Cu(II) were 1.81 and 1.03%, respectively. The calibration curve was linear for 2–220 μg/L copper(II). The resulting CPE does not use mercury and therefore, has a positive environmental benefit. The method, which is reasonably sensitive and selective, has been successfully applied to the determination of trace amount of copper in water and human hair samples.
Compositional effects on electrophoretic and chromatographic figures of merit in electrokinetic chromatography with cetyltrimethylammonium bromide/sodium octyl sulfate vesicles as the pseudostationary phase. Part 1: Effect of the phase ratio
Authors: Foley Joe P. , Hong Mei , Polinko Michelle A. , Pascoe Robert J. , Ahuja Eric S.
Published: February 2008

The effect of the phase ratio on the electrophoretic and chromatographic properties of unilamellar vesicles comprised of cetyltrimethylammonium bromide (CTAB) and sodium octyl sulfate (SOS) was investigated in EKC. The surfactant concentration of the vesicles was 0.9, 1.2, 1.5, and 1.8% w/v, with a mole ratio of 1:3.66 (CTAB/SOS). Results were compared to those obtained using SDS micelles at concentrations of 1.0% (w/v, 35 mM) and 1.5% (52 mM). The CTAB/SOS vesicles (0.9–1.8% w/v) provided a significantly larger elution range (5.7 ≤ tves/t0 ≤ 8.7) and greater hydrophobic (methylene) selectivity (2.8 ≤ αCH2 ≤ 3.1) than SDS micelles (3.1 ≤ tmc/t0 ≤ 3.3; αCH2 = 2.2). Whereas the larger elution range can be attributed to the 25% reduction in EOF due to the interaction of unaggregated CTAB cations and the negatively charged capillary wall, the higher methylene selectivity is likely due to the lower concentration of water expected in the CTAB/SOS vesicle bilayer compared to the Palisades layer of SDS micelles. For a given phase ratio, CTAB/SOS vesicles are somewhat less retentive than SDS micelles, although retention factors comparable to those observed in 1.0–1.5% SDS can be obtained with 1.5–1.8% CTAB/SOS. A linear relationship was observed between phase ratio and retention factor, confirming the validity of the phase ratio model for these vesicles. Unique polar group selectivities and positional isomer shape selectivities were obtained with CTAB/SOS vesicles, with both types of selectivities being nearly independent of the phase ratio. For four sets of positional isomers, the elution order was always para < ortho < meta. Finally, the thermodynamics of solute retention was qualitatively similar to that reported for other surfactant aggregates (micelles and microemulsions); the enthalpic contribution to retention was consistently favorable for all compounds, whereas the entropic contribution was favorable only to hydrophobic solutes.
Development of Low‐Cost Advanced Composite Bipolar Plate for Proton Exchange Membrane Fuel Cell�
Authors: Kakati B. K. , Mohan V.
Published: February 2008

The bipolar plate is one of the most imperative components of proton exchange membrane fuel cells (PEMFC) which consumes up to 80% of weight and near about 50% of the total cost of the cell. Development of cost‐effective composite bipolar plate with high electrical conductivity and high mechanical strength is both technically and economically demanding. In this paper, a low‐cost advanced composite bipolar plate is developed by bulk moulding compression (BMC) technique. It is clear from the experiments that by increasing the matrix volume fraction, bulk density and electrical conductivity of a composite bipolar plate decrease but shore hardness increases. Test results clearly show that best overall properties are achieved when a constant volume fraction of polymer matrix and natural graphite is reinforced with synthetic graphite, carbon black and carbon fibre. This bipolar plate was found to have high conductivity, less porosity and high mechanical strength. The I–V characteristics in single cell test exhibited more uniform power density at both higher and lower current densities
Design of BaZr0.8Y0.2O3–δ Protonic Conductor to Improve the Electrochemical Performance in Intermediate Temperature Solid Oxide Fuel Cells (IT‐SOFCs)
Authors: D'Epifanio A. , Fabbri E. , Di Bartolomeo E. , Licoccia S. , Traversa E.
Published: February 2008

BaZr0.8Y0.2O3–δ, (BZY), a protonic conductor candidate as an electrolyte for intermediate temperature (500–700 °C) solid oxide fuel cells (IT‐SOFCs), was prepared using a sol–gel technique to control stoichiometry and microstructural properties. Several synthetic parameters were investigated: the metal cation precursors were dissolved in two solvents (water and ethylene glycol), and different molar ratios of citric acid with respect to the total metal content were used. A single phase was obtained at a temperature as low as 1,100 °C. The powders were sintered between 1,450 and 1,600 °C. The phase composition of the resulting specimens was investigated using X‐ray diffraction (XRD) analysis. Microstructural characterisation was performed using field emission scanning electron microscopy (FE‐SEM). Chemical stability of the BZY oxide was evaluated upon exposure to CO2 for 3 h at 900 °C, and BZY showed no degradation in the testing conditions. Fuel cell polarisation curves on symmetric Pt/BZY/Pt cells of different thicknesses were measured at 500–700 °C. Improvements in the electrochemical performance were obtained using alternative materials for electrodes, such as NiO‐BZY cermet and LSCF (La0.8Sr0.2Co0.8Fe0.2O3), and reducing the thickness of the BZY electrolyte, reaching a maximum value of power density of 7.0 mW cm–2 at 700 °C.
Hard Rock TBM Cutterhead Modeling for Design and Performance Prediction
Authors: Rostami Jamal
Published: February 2008

As the use of hard rock TBMs constantly continues to grow, so are the experiences gained in these projects and the challenges that need new solutions. Cutterhead modeling has been a successful tool used by the industry at various levels of sophistications relative to the end use. These models are based on the estimation of the cutting forces and can be used for cutterhead design optimization as well as performance estimates. While these models have proven to be useful in these areas, there is still room for improving their accuracy to account for different rock features and rock mass properties. New and emerging technologies in cutter and machine manufacturing can be assisted by the use of these models in optimizing their use or assessing their potentials. This paper reviews the state of the art of modeling used for design and performance prediction of hard rock TBMs. A brief overview of the available models will be offered and their strength and shortcomings will be discussed.
An Integrated Approach to Penetration, Advance Rates and Disc Cutter Wear for Hard Rock TBM Drives
Authors: Alber Michael
Published: February 2008

Tunnel boring machines (TBM) are increasingly used for excavating subsurface infrastructure such as road and railway, water supply and sewer tunnels, to name a few applications. When designing a hard rock TBM drive it is necessary to appreciate all interactions of the rock mass to be tunnelled with the TBM. This paper deals specifically with these interactions and suggests an integrated approach in estimating hard rock TBM performance, such as the penetration rate, the advance rate and the disc cutter wear.
Abrasiveness Assessment for Hard Rock Drilling
Authors: Plinninger Ralf J.
Published: February 2008

The wear of drilling tools in mining and tunnelling has always been a predominant factor for the costs of hard rock excavation. This fact is not only related to material and personnel costs arising from drill bit maintenance and replacement but also because of the direct and negative impact of a worn drill bit on the drilling performance. This paper presents typical machinery, tools and basic findings on wear and performance interactions as well as drilling tool wear mechanisms. Based on this theoretical background, methods and classifications for on‐site investigation of encountered tool wear rate and wear types are presented. The paper then summarises laboratory approaches for assessing of rock abrasiveness in order to predict drilling tool wear from geotechnical investigations.
Prediction of Wear of Roadheader Picks Using Numerical Simulations
Authors: Rojek Jerzy , Oñate Eugenio , Kargl Hubert , Labra Carlos , Akerman Jan , Restner Uwe , Lammer Egmont , Zarate Francisco
Published: February 2008

The paper presents prediction of wear of roadheader picks using numerical simulations. Estimation of wear has been included into the numerical model of rock cutting based on the discrete element method. The amount of wear is calculated using the classical formula of Archard. The wear model takes the influence of temperature by considering the hardness of the worn material as temperature dependent into account. The set of parameters for the discrete element model has been established by a calibration procedure based on numerical simulation of the unconfined compression and Brazilian tests, with the results of laboratory tests as reference data. After having established model parameters, numerical simulation of cutting process with a roadheader pick has been carried out. The simulation provides values and variation of cutting forces. Temperature increase due to frictional heat is obtained in the thermo‐mechanical simulation of cutting. Numerical analysis yields the wear profile as well as the tool shape evolution due to wear. The numerical model developed allows studying the wear intensity for different cutting process parameters. The developed method can be employed in the design of cutting heads and cutting operations in underground excavations with roadheaders.
Factors Influencing Disc Cutter Wear
Authors: Frenzel Christian , Käsling Heiko , Thuro Kurosch
Published: February 2008

Disc cutter wear in mechanised tunnelling has a strong influence on costs and performance in hard rock and soil materials. Wear is affected by several geological and technical factors. Several aspects have been considered in prediction models and case studies. In this paper the essential technical influences are presented in a systematic way and are further analysed based on jobsite experience. Modifications in the operation of a TBM like adjustments of the cutterhead rotation or thrust lead to less disc cutter wear at comparable advance. A geological mapping during the tunnelling process, regular cutterhead inspections and tool wear measurements in combination with penetration tests will improve the work and results in a more economic tunnelling process.
The Influence of the Parameter “Temperature” on the Abrasiveness of Rock
Authors: Eberl Stefan , Restner Uwe , Galler Robert , Mali Heinrich
Published: February 2008

The article deals with the influence of temperature produced in the cutting process on rock abrasiveness and tool wear. Basically it was to clarify which effects take place when quartz or rock with significant quartz content is heated up to a certain temperature. Does the quartz jump from low into high quartz happening at 573 °C cause an increase in abrasiveness of mineral and rock or not? To find out, a certain number of Cerchar abrasiveness index tests were done for a detailed investigation of this topic. Additionally, to get a better understanding what really happens inside rock structure additionally other rock parameters like unconfined compressive strength, Brazilian tensile strength, ultrasonic wave velocity and density were determined on untreated and heated and subsequently cooled down rock samples. The final output of the research work showed that rocks show a very specific and significant reaction to thermal stresses induced into their structure resulting in a different behaviour regarding abrasiveness and fracturing.