bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiation model of a TiO2‐coated, quartz wool, packed‐bed photocatalytic reactor
Authors: Imoberdorf G. E. , Vella G. , Sclafani A. , Rizzuti L. , Alfano O. M. , Cassano A. E.
Published: December 2009

The radiation field of a packed‐bed photocatalytic reactor filled with quartz wool coated with titanium dioxide was modeled using the Monte Carlo technique and the following information: the radiation flux emitted by the lamps, the diameter size distribution of the quartz fiber cloth, the mass of quartz fibers and of TiO2 that was immobilized on the fiber surface as well as the refractive index, and the spectral absorption coefficient of the materials of the system. Modeling predictions were validated with radiometer measurements of the transmitted radiation through the reactor, the root mean square error being <9.7%. Finally, by means of a parametric study, the validated model was used to analyze the effect of the design variables, such as the radii of the quartz fibers, thickness of the TiO2 coatings, and amount of TiO2‐coated quartz wool, on the distribution and nonuniformity of the radiative energy distribution inside the reactor. © 2009 American Institute of Chemical Engineers AIChE J, 2010
Hedgehog signaling: Endocrine gland development and function
Authors: Cohen M. Michael
Published: December 2009

The role of hedgehog signaling is analyzed in relation to the developing endocrine glands: pituitary, ovary, testis, adrenal cortex, pancreas, prostate, and epiphyseal growth. Experimental and pathological correlates of these organs are also discussed. The second section addresses a number of topics. First, the pituitary gland, no matter how hypoplastic, is present in most cases of human holoprosencephaly, unlike animals in which it is always said to be absent. The difference appears to be that animal mutations and teratogenic models involve both copies of the gene in question, whereas in humans the condition is most commonly heterozygous. Second, tests of endocrine function are not reported with great frequency, and an early demise in severe cases of holoprosencephaly accounts for this trend. Reported tests of endocrine function are reviewed. Third, diabetes insipidus has been recorded in a number of cases of holoprosencephaly. Its frequency is unknown because it could be masked by adrenal insufficiency in some cases and may not be recognized in others. Because of the abnormal hypothalamic‐infundibular region in holoprosencephaly, diabetes insipidus could be caused by a defect in the supra‐optic or paraventricular hypothalamic nuclei or in release of ADH via the infundibulum and posterior pituitary. © 2009 Wiley‐Liss, Inc.
Drug loading onto and release from wheat gluten fibers
Authors: Xu Weijie , Yang Yiqi
Published: December 2009

Drug release and its relationship with kinetic and thermodynamic parameters of drug sorption onto wheat gluten (WG) fibers have been studied using Diclofenac, 5‐Fluorouracil (5‐Fu), and Metformin as model drugs. Both sorption and dissolution methods were used to examine the drug release rates in phosphate buffered saline (PBS pH 7.4) and artificial gastric juice (AGJ pH 1.2). To understand drug release of WG fibers using the sorption loading method, kinetic, and apparent thermodynamic parameters, such as diffusion coefficient, activation energy for diffusion, affinity, and sorption enthalpy and entropy, have been investigated. It has been found that the sorption method at high temperatures has a lower initial burst and more constant release than the dissolution method for Diclofenac on WG fibers. Quantitative relationship between drug release and drug loading concentration, affinity, and activation energy for diffusion was established to predict initial bursts and later release of the drugs. The study showed that the Diclofenac had high initial bursts in PBS but more constant release in AGJ because the ionic force between the drug and WG fibers was readily broken in a high pH solution. It also has been found that drugs with higher activation energy for diffusion, lower diffusion coefficients, and higher affinity (especially van der Waals force) on WG fiber, are more suitable for sorption loading at elevated temperatures to achieve higher loading capacity and more constant releasing rate. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Influence of polyurethane properties on mechanical performances of magnetorheological elastomers
Authors: Wei Bing , Gong Xinglong , Jiang Wanquan
Published: December 2009

Magnetorheological elastomers (MREs) are mainly composed of magnetizable particles and elastic polymer. The polymer matrix plays an important role in mechanical performances of MREs. In this study, the polyurethane (PU), which is synthesized by using toluene diisocyanate (TDI) and poly (propylene glycol) (PPG‐220), is selected as a matrix because it has better degradation stability than natural rubber and higher mechanical stability than silicone rubber. Four different MRE samples were fabricated by adjusting the reaction molar ratio of TDI to PPG to change the property of PU matrix. Structural characterization of the PU matrix was described by Fourier transform infrared analysis. The microstructures of samples were observed by using an environmental scanning electron microscope. The mechanical performances of samples, including shear modulus, magnetorheological effect (MR) effect, loss factor, and glass transition temperature (Tg), were characterized with dynamic mechanical analyzer. The results show that the shear modulus, the relative magnetic residual shear modulus and glass transition temperatures of samples increase with the increment of toluene diisocyanate, while the relative MR effects and loss factors decrease steadily. The experimental results indicate that optimal molar ratio (TDI : PPG) is 3 : 1. The field‐induced shear modulus of sample with molar ratio 3 : 1 is 4.9 MPa, and the relative MR effect is 121% under an external magnetic field of 800 mT at room temperature. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Influence of the solvent evaporation rate on the crystalline phases of solution‐cast poly(vinylidene fluoride) films
Authors: Chinaglia Dante Luis , Gregorio Rinaldo , Stefanello Josiani Cristina , Pisani Altafim Ruy Alberto , Wirges Werner , Wang Feipeng , Gerhard Reimund
Published: December 2009

The influence of the solvent‐evaporation rate on the formation of α and β crystalline phases in solution‐cast poly(vinylidene fluoride) (PVDF) films was systematically investigated. Films were crystallized from PVDF/N,N‐dimethylformamide solutions with concentrations of 2.5, 5.0, 10, and 20 wt % at different temperatures. During crystallization, the solvent evaporation rate was monitored in situ by means of a semianalytic balance. With this system, it was possible to determine the evaporation rate for different concentrations and temperatures of the solution under specific ambient conditions (pressure, temperature, and humidity). Fourier‐Transform InfraRed spectroscopy with Attenuated Total Reflectance revealed the β‐phase content in the PVDF films and its dependence on previous evaporation rates. Based on the relation between the evaporation rate and the PVDF phase composition, a consistent explanation for the different amounts of β phase observed at the upper and lower sample surfaces is achieved. Furthermore, the role of the sample thickness has also been studied. The experimental results show that not only the temperature but also the evaporation rate have to be controlled to obtain the desired crystalline phases in solution‐cast PVDF films. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Cyclic dithia/diaza with dual Schiff base linkage functionalized polymers for heavy metal adsorption
Authors: Nutthanara Pradit , Ngeontae Wittaya , Imyim Apichat , Kreethadumrongdat Thanapong
Published: December 2009

Three new types of functionalized polystyrene‐divinylbenzene resins containing two sulfur and two nitrogen atoms and four nitrogen atoms in cyclic form were prepared by using two lab‐synthesized ligands; 2‐[3‐(2‐amino ethylsulfanyl)‐propylsulfanyl]‐ethylamine (AEPE) and 2‐[2‐(2‐amino‐ethylsulfanyl)‐ethylsulfanyl]‐ethylamine (AEEE), and a commercial one; triethylenetetramine (TETA). Chloromethylated polystyrene‐divinylbenzene copolymer (Cl‐PS‐DVB) was initially oxidized to aldehydic polystyrene‐divinylbenzene (CHO‐PS‐DVB) with approximately 57% yield. CHO‐PS‐DVB was subsequently reacted with the ligands through dual Schiff base linkage. The products were named AEPE‐PS‐DVB, AEEE‐PS‐DVB and TETA‐PS‐DVB, respectively. The optimum coupling reaction times and temperatures were 6 h at 50°C for AEPE‐PS‐DVB, AEEE‐PS‐DVB and 6 h at room temperature for TETA‐PS‐DVB. The appropriate amount of the three ligands was 2.65 mmol/g CHO‐PS‐DVB corresponding to the mole ratio between the chelating ligand and aldehyde group of 1 : 2. All derivative resins were characterized by elemental analysis, thermogravimetry, FT‐IR and FT‐Raman spectroscopy and Ninhydrin test. The adsorption properties of the synthesized resins towards Pb(II), Cu(II), Cd(II), Zn(II), Ni(II), Co(II) and Cr(III) ions in aqueous solution were preliminarily investigated by batch method. AEPE‐PS‐DVB and AEEE‐PS‐DVB showed the same sorption behavior. Their selectivity order was Pb(II) > Zn(II) > Cu(II) > Cd(II) and no significant adsorption for Co(II), Ni(II), Cr(III) was observed. In addition, TETA‐PS‐DVB showed a selectivity toward only Pb(II). © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation and characterization of poly(vinylidene fluoride)/sulfonated poly(phthalazinone ether sulfone ketone) blends for proton exchange membrane
Authors: Gu Shuang , He Gaohong , Wu Xuemei , Hu Zhengwen , Wang Leilei , Xiao Gongkui , Peng Lin
Published: December 2009

Poly(vinylidene fluoride)/sulfonated poly(phthalazinone ether sulfone ketone) (PVdF/SPPESK) blend membranes are successfully prepared by solution blending method for novel proton exchange membrane (PEM). PVdF crystallinity, FTIR‐ATR spectroscopy, thermal stability, morphology, water uptake, dimension stability, and proton conductivity are investigated on PVdF/SPPESK blends with different PVdF contents. XRD and DSC analysis reveal that the PVdF crystallinity in the blends depends on PVdF content. The FTIR‐ATR spectra indicate that SPPESK remains proton‐conducting function in the blends due to the intactness of SO3H group. Thermal analysis results show a very high thermal stability (Td1 = 246–261°C) of the blends. PVdF crystallinity and morphology study demonstrate that with lower PVdF content, PVdF are very compatible with SPPESK. Also, with lower PVdF content, PVdF/SPPESK blends possess high water uptake, e.g., P/S 10/90 and P/S 15/85 have water uptake of 135 and 99% at 95°C, respectively. The blend membranes also have good dimension stability because the swelling ratios are at a fairly low level (e.g., 8–22%, 80°C). PVdF/SPPESK blends with low PVdF content exhibit very high proton conductivity, e.g., at 80°C, P/S 15/85 and P/S 10/90 reach 2.6 × 10−2 and 3.6 × 10−2 S cm−1, respectively, which are close to or even higher than that (3.4 × 10−2 S cm−1) of Nafion115 under the same test condition. All above properties indicate that the PVdF/SPPESK blend membranes (particularly, with 10–20% of PVdF content) are very promising for use in PEM field. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Positive temperature coefficient properties of multiwall carbon nanotubes/poly(vinylidene fluoride) nanocomposites
Authors: Jiang S. L. , Yu Y. , Xie J. J. , Wang L. P. , Zeng Y. K. , Fu M. , Li T.
Published: December 2009

Favorable positive temperature coefficient (PTC) properties of multiwall carbon nanotubes (MWCNT)/poly(vinylidene fluoride) (PVDF) nanocomposites were obtained. The results showed that such composites presented high PTC intensity, as well as eliminated negative temperature coefficient effect and high thermal stability, which indicated that the MWCNT/PVDF nanocomposites could overcome the main shortages of the current polymer‐based PTC composites. By comparing with other contrastive nanocomposites through similar procedure, the mechanisms for the MWCNT/PVDF composite to overcome the shortages were studied and discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Biophysical studies on bone cement composites based on polyester fumarate
Authors: Kamel N. A. , Abou‐Aiaad T. H. , Iskander B. A. , Khalil S. K. H. , Mansour S. H. , Abd‐El‐Messieh S. L. , Abd‐El‐Nour K. N.
Published: December 2009

Polypropylene fumarate (PPF) as unsaturated linear polyester crosslinked with three different monomers namely N‐vinyl pyrrolidone (NVP), methyl methacrylate (MMA), and a mixture of NVP/MMA (1 : 1 weight ratio) were prepared. The chemical structure of the PPF was characterized by means of 1H‐NMR, FTIR, as well as GPC. The mixture of PPF resin with the crosslinking monomers filled with (60, 65, and 70 wt %) of gypsum were also prepared as bone cement composites. The dielectric measurements carried out on these prepared samples at frequency range from 100 Hz–100 kHz indicate that the permittivity ε′ and dielectric loss ε″ follow the order NVP > NVP/MMA > MMA. Both parameters were found to decrease by increasing the percentage of gypsum. According to Fröhlich and Havriliak Nagami functions, the relaxation times obtained could be attributed, respectively, to Maxwell‐Wagner effect and to the relaxation process related to carboxyl, hydroxyl, and ester functions associated with main chain. The latter relaxation time was found to increase by increasing gypsum content, whereas the electrical conductivity was found to decrease. The mechanical data of the investigated samples containing 60 wt % gypsum is characterized by the best properties and the behavior of the composites follows the order found in the case of dielectric properties (NVP > NVP/MMA > MMA). Formation of carbonate apatite of composite samples loaded with 60 wt % gypsum after immersing the samples for 4 weeks in simulated body fluid (SBF) was confirmed by the dielectric measurements and FTIR spectroscopy. In addition, the weight loss and the mechanical properties for such systems were also studied. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Preparation and properties of highly branched waterborne poly(urethane‐urea) via A2 + B3 approach
Authors: Hu Qian , Liu Dan , Zeng Shaomin , Yi Changfeng , Xu Zushun
Published: December 2009

A series of highly branched waterborne poly(urethane‐urea)s (HBWPUs) containing pendant carboxylate anion as the hydrophilic groups were prepared via A2 + B3 approach using isocyanate end‐capped polycarbonatediols as an A2 oligomeric monomer and triamine as a B3 monomer. The structure of the products were characterized by FTIR and 13C‐NMR. The particle size, solution viscosity, thermal and mechanical properties were measured by photon correlation spectroscopy (PCS), rotational rheometer, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA) and tensile tests, respectively. It was found that the particles size mainly depended on the molar ratio of nNCO/nOH and the content of hydrophilic groups; the HBWPUs showed lower viscosity but higher Tg compared with linear waterborne polyurethane. The tensile testing, DMA measurements and rehological measurements revealed that the molar ratio of [B3]/[A2] had significant influence on the viscosity and tensile strength. With increasing the molar ratio of [B3]/[A2], both the viscosity and the tensile strength decreased. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Electrospinning of antibacterial poly(vinylidene fluoride) nanofibers containing silver nanoparticles
Authors: Yuan Jiang , Geng Jia , Xing Zhicai , Shen Jian , Kang Inn‐Kyu , Byun Hongsik
Published: December 2009

Poly(vinylidene fluoride) (PVDF) nanofibrous mats containing silver nanoparticles were prepared by electrospinning. The diameter of the nanofibers ranged between 100 and 300 nm, as revealed by scanning electron microscopy. The silver nanoparticles were dispersed, but some aggregation was observed with transmission electron microscopy. The content of silver nanoparticles incorporated into the PVDF nanofibrous mats was determined by inductively coupled plasma and X‐ray photoelectron spectroscopy. The antibacterial activities of the samples were evaluated with the colony‐counting method against Staphylococcus aureus (Gram‐positive) and Klebsiella pneumoniae (Gram‐negative) bacteria. The results indicate that the PVDF nanofibrous mats containing silver nanoparticles showed good antibacterial activity compared to the PVDF nanofiber control. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Comparative delivery of Diltiazem hydrochloride through synthesized polymer: Hydrogel and hydrogel microspheres
Authors: Ray Debajyoti , Gils P. Sunny , Mohanta Guru P. , Manavalan R. , Sahoo Prafulla K.
Published: December 2009

In this study, interpenetrating polymer network (IPN) hydrogel based on polyvinyl alcohol (PVA) networking with polyacrylic acid (PAA) were prepared by a non‐conventional emulsion method without any added crosslinker, using benzoyl peroxide as initiator and sodium chloride (NaCl) as additive. The IPN hydrogel was characterized by using Fourier transformed infrared (FTIR) spectrophotometry, Thermo gravimetric analysis (TGA), and Scanning electron microscopy (SEM). (PVA‐co‐PAA)/NaCl normal IPN hydrogel (H) were fabricated into hydrogel microspheres (HM) by modified emulsion crosslinking method using glutaraldehyde‐saturated toluene as crosslinker and were loaded with Diltiazem hydrochloride (DL). The IPN hydrogel showed more swelling in simulated intestinal fluid (SIF). (PVA‐co‐PAA)/NaCl HM formulation A1 showed comparatively higher DL entrapment (79%) and better control over DL release up to 24 h. By comparing antihypertensive activity of DL loaded two formulations in normotensive rats, HM formulation A1 found more effective in reducing blood pressure to 40.1%. The experimental results demonstrated that (PVA‐co‐PAA)/NaCl HM had the greater potential than normal hydrogel to be used as a drug carrier. A single use of the prepared hydrogel microsphere system of DL can effectively control hypertension in rats. The system holds promise for clinical studies. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Hans Peter Luhn and Herbert M. Ohlman: Their roles in the origins of keyword‐in‐context/permutation automatic indexing
Authors: Williams Robert V.
Published: December 2009

The invention of automatic indexing using a keyword‐in‐context approach has generally been attributed solely to Hans Peter Luhn of IBM. This article shows that credit for this invention belongs equally to Luhn and Herbert Ohlman of the System Development Corporation. It also traces the origins of title derivative automatic indexing, its development and implementation, and current status.
User‐producer interaction in Web site development: Motives, modes, and misfits
Authors: van Rijnsoever Frank J. , Faber Jan , Brinkman Marnix L.J. , van Weele Marijn A.
Published: December 2009

This paper studies the role and effects of user‐producer interaction (UPI) in the production of Web sites. The results of two empirical studies, one from a producer perspective and one from a user perspective, are presented. It is concluded that using UPI in the development of informative Web sites for a large public is a risky process, because it is hard to identify and define the most targeted users and their particular needs. The implications of these results are discussed.
Requirements for the design of a personal document‐management system
Authors: Bondarenko Olha , Janssen Ruud , Driessen Samuël
Published: December 2009

In this article a set of requirements for the design of a personal document management system is presented, based on the results of three research studies (Bondarenko, 2006; Bondarenko & Janssen, 2005; Bondarenko & Janssen, 2009). We propose a framework, based on layers of task decomposition, that helps to understand the needs of information workers with regard to personal document and task management. Relevant user processes are described and requirements for a document‐management system are derived for each layer. The derived requirements are compared to related studies, and implications for system design are discussed.
Human spleen tyrosine kinase (Syk) recombinant expression systems for high‐throughput assays
Authors: Singh Deepika , Rani Reema , Rajendran Resmi , Kaur Namrata Jit , Pandey Abhinav , Chopra Puneet , Jain Tarun , Jain Manish Kumar , Grover Sonam , Arya Ranjana , Saini Kulvinder Singh
Published: December 2009

Spleen tyrosine kinase (Syk) is an important non‐receptor tyrosine kinase and its aberrant regulation is associated with a variety of allergic disorders and autoimmune diseases. To identify small molecule inhibitors of Syk in high‐throughput assays, recombinant Syk protein is needed in bulk quantity. We studied the expression of recombinant human Syk in three heterologous systems: E. coli, baculovirus expression vector system (BEVS), and the cellular slime mold Dictyostelium discoideum (Dd). Syk activity was higher in the BEVS as compared to the Dd expression host, whereas in E. coli, no activity was observed under our assay conditions. Purified Syk kinase domain protein from BEVS showed concentration dependent inhibition with OXSI‐2, a known Syk inhibitor. Molecular modeling and docking studies were performed to understand the binding mode and critical interactions of the inhibitor with catalytic domain of Syk. The BEVS generated Syk kinase domain showed stability upon multiple freeze‐thaw cycles and exhibited significantly higher levels of tyrosine phosphorylation at pTyr525/Tyr526 in the Syk activation loop. Based on our data, we conclude that BEVS is the ideal host to produce an active and stable enzyme, which can be successfully employed for screening of Syk inhibitors in a high‐throughput system.
Siebengebirge – im Saum der Großlandschaften. Die Exkursion
Authors: Kremer Bruno P.
Published: December 2009

Das rechtsrheinisch gegenüber Bonn gelegene Siebengebirge weist zwar nur eine Fläche von etwa 4800 ha auf, stellt aber als Landschaft ebenso wie als Naturraum ein recht ungewöhnliches Gefüge dar. Über kaum eine zweite Teillandschaft Deutschlands liegen vergleichbar zahlreiche Einzeluntersuchungen und Gesamtdarstellungen vor. Ein Exkursionsvorschlag entführt in diese faszinierende Teilregion am Ende des Unteren Mittelrheintals.
Gedanken‐Gang: Neue Ausstellung zum Gehirn im Weltkulturerbe Völklinger Hütte
Authors: Högermann Christiane
Published: December 2009

In der 1994 zum UNESCO‐Weltkulturerbe erklärten Völklinger Hütte lassen sich alle Phasen der Roheisenerzeugung an Originalschauplätzen nacherleben. Doch zunehmend treten auch multimediale Ausstellungsformen in den Vordergrund, so im 2004 eröffneten “Ferrodrom”, dem ersten Science‐Center im Saarland. Die Erzhalle der Völklinger Hütte ist das ideale Szenario für die spektakuläre Ausstellung “Dein Gehirn: denken, fühlen, handeln”.
Growth rates of small abdominal aortic aneurysms correlate with clinical events
Authors: Thompson A R , Cooper J A , Ashton H A , Hafez H
Published: December 2009

Background

This retrospective analysis of prospectively collected abdominal aortic aneurysm (AAA) screening data aimed to identify predictors of AAA-related events (surgery or death) with a view to better targeting of screening.

Methods

For the interval 1984–2007, data for 1649 subjects with an AAA were collected prospectively as part of the Chichester AAA screening programme. This included serial aortic size measurements, blood pressure, risk factors for arterial disease and concurrent medications. AAA growth rates were adjusted for risk factor confounders using flexible hierarchical modelling. AAA growth distribution was analysed using Silverman's test of multimodality.

Results

Some 1231 subjects met the inclusion criteria of having more than one scan and a surveillance interval of over 3 months. AAA growth showed a bimodal pattern with nearly 50 per cent of all aneurysms never progressing to surgery or rupture. Adjusted annual AAA growth rates of at least 2 mm significantly predicted AAA-related events.

Conclusion

This analysis identified a bimodal growth pattern for AAA, with a significant association between annual AAA growth rate of at least 2 mm and AAA-related events.
Clinical outcomes of ileorectal anastomosis for ulcerative colitis
Authors: da Luz Moreira A , Kiran R P , Lavery I
Published: December 2009

Background

The aim of this study was to determine the fate of the rectum, functional results and quality of life after ileorectal anastomosis (IRA) in ulcerative colitis.

Methods

Patients with ulcerative colitis and indeterminate colitis who underwent IRA from 1971 to 2006 were evaluated retrospectively. Twenty-two patients with an IRA were matched by age, sex and follow-up duration with 66 patients with an ileal pouch–anal anastomosis (IPAA) and compared for functional outcomes and quality of life.

Results

Eighty-six patients with an IRA were included. Median follow-up was 9 (range 1–36) years. Rectal dysplasia and cancer rates were 17 and 8 per cent respectively. The rectum was resected in 46 patients (53 per cent) because of refractory proctitis in 24, rectal dysplasia in 15 and rectal cancer in seven. The cumulative probability of having a functioning IRA at 10 and 20 years was 74 and 46 per cent respectively. Patients with an IRA had fewer bowel movements (P = 0·020) and less night-time seepage (P = 0·020) but increased urgency (P < 0·001) compared with patients with an IPAA, whereas quality of life was similar.

Conclusion

In selected patients with ulcerative colitis IRA gives an acceptable quality of life and functional outcome that are comparable to those in patients with an IPAA. Owing to the risk of cancer, surveillance of the rectum is mandatory.
Biomimetic Formation of 2‐Tropolones by Dioxygenase‐Catalysed Ring Expansion of Substituted 2,4‐Cyclohexadienones
Authors: Xin Meite , Bugg Timothy D. H.
Published: December 2009

Substituted 2‐tropolone natural products are found in plants and fungi. Their biosynthesis is thought to occur by ring expansion from a cyclohexadienone precursor, but this reaction has not previously been demonstrated experimentally. Treatment of 6‐hydroxy‐6‐hydroxymethylcyclohexa‐2,4‐dienone with the non‐haem iron(II)‐dependent extradiol catechol dioxygenase MhpB from Escherichia coli results in the formation of the 2‐tropolone ring‐expansion product through a pinacol‐type rearrangement. Three further substituted cyclohexa‐2,4‐dienone analogues were prepared, and treatment of each analogue was found to give the substituted 2‐tropolone ring‐expansion product. This ring expansion could also be effected nonenzymatically by treatment with 1,4,7‐triazacyclononane and FeCl2. This is a novel transformation for non‐haem iron‐dependent enzymes, and this is the first experimental demonstration of the proposed ring‐expansion reaction in tropolone biosynthesis.
Efficient Aerobic Wacker Oxidation of Styrenes Using Palladium Bis(isonitrile) Catalysts
Authors: Naik Anu , Meina Liu , Zabel Manfred , Reiser Oliver
Published: December 2009

The palladium‐catalyzed aerobic oxidation of alkenes and especially styrenes (Wacker oxidation) by using chiral pseudo C2‐symmetrical bis(isonitrile) ligands in the absence of further cocatalysts gives rise to methyl ketones in a highly chemoselective manner. The palladium bis(isonitrile) catalyst was characterized by NMR spectroscopy and X‐ray structure analysis, revealing a dissymmetric coordination of palladium by the two isonitrile moieties.
Highly Enantioselective Synthesis of β‐Heteroaryl‐Substituted Dihydrochalcones Through Friedel–Crafts Alkylation of Indoles and Pyrrole
Authors: Wang Wentao , Liu Xiaohua , Cao Weidi , Wang Jun , Lin Lili , Feng Xiaoming
Published: December 2009

A highly enantioselective Friedel–Crafts (F–C) alkylation of indoles and pyrrole with chalcone derivatives catalyzed by a chiral N,N′‐dioxide–Sc(OTf)3 complex has been developed that tolerates a wide range of substrates. The reaction proceeds in moderate to excellent yields and high enantioselectivities (85–92 % enantiomeric excess) using 2 mol % (for indole) or 0.5 mol % (for pyrrole) catalyst loading, which showed the potential value of the catalyst system. Meanwhile, a strong positive nonlinear effect was observed. On the basis of the experimental results and previous reports, a possible working model is proposed to explain the origin of the activation and asymmetric induction.
Axially chiral N‐(o‐aryl)‐4‐hydroxy‐2‐oxazolidinone derivatives from diastereoselective reduction of N‐(o‐aryl)‐2,4‐oxazolidinediones: Thermally interconvertible atropisomers via ring‐chain‐ring tautomerization
Authors: Demir‐Ordu Öznur , Doǧan İlknur
Published: December 2009

The reduction of the axially chiral N‐(o‐aryl)‐5,5‐dimethyl‐2,4‐oxazolidinediones by NaBH4 yielded axially chiral N‐(o‐aryl)‐4‐hydroxy‐5,5‐dimethyl‐2‐oxazolidinone enantiomers having a chiral center at C‐4, with 100% diastereoselectivity as has been shown by their 1H and 13C NMR spectra and by enantioselective HPLC analysis. The resolved enantiomeric isomers were found to interconvert thermally through an aldehyde intermediate formed upon ring cleavage via a latent ring‐chain‐ring tautomerization. It was found that the rate of enantiomerization depended on the size and the electronic effect of the ortho substituent present on the aryl ring bonded to the nitrogen of the heterocycle. Chirality 2010. © 2009 Wiley‐Liss, Inc.
Alignment of Carbon Nanotubes in Thermotropic and Lyotropic Liquid Crystals
Authors: Scalia Giusy
Published: December 2009

The organization of carbon nanotubes is an important but challenging issue. This Minireview focuses on a novel approach based on the use of liquid crystals as host for nanotube dispersion and ordering. With these self‐organizing fluids it is possible to control the nanotube orientation on a macroscopic scale, as the orientational order of the liquid crystal, the direction of which can easily be selected and dynamically modulated, is transferred onto embedded carbon nanotubes. Both main classes of liquid crystals, thermotropics and lyotropics, have been used successfully. This reveals an aligning mechanism resulting from the liquid crystallinity per se, independent of specific molecular structures, although these can affect the degree of order and the quality of the tube dispersion. The enormous variety of systems that form liquid crystalline phases provides additional strength and potentialities to the liquid‐crystal‐based route towards nanotube alignment. The exploration of this new use of liquid crystals has just started, hence we can expect exciting developments in the years to come.
Neuroanatomical basis for therapeutic applications of cannabinoid receptor 1 antagonists
Authors: Thomas Brian F.
Published: December 2009

The CB1 receptor is a Class A G‐protein coupled receptor that has a high density and widespread distribution within the central nervous system. Because of its neuroanatomical distribution, the endocannabinoid system can modulate a wide variety of psychological and physiological functions. For example, CB1 receptors are found in brain regions regulating motor activity, cognitive processes, pain, satiety, appetitive behaviors and reward. In correspondence with this distribution, modulation of the endocannabinoid system has been shown to produce changes in coordination, executive function, memory, mood, perception, wakefulness, nociception and appetite. Administration of cannabinoid agonists has also been therapeutically used to reduce nausea, and is also known to decrease body temperature and neuronal excitability, pointing to additional roles for endocannabinoids in these and other physiological/neurological processes. The ongoing elucidation and characterization of the neuroanatomical circuitry within which the CB1 cannabinoid receptor and endocannabinoids are localized to modulate these psychological and physiological processes continues to suggest therapeutic applications for cannabinoid antagonists and inverse agonists. Drug Dev Res 70:527–554, 2009. © 2009 Wiley‐Liss, Inc.
Construction of simulation model for spray flash desalination system
Authors: Goto Satoru , Yamamoto Yuji , Sugi Takenao , Yasunaga Takeshi , Ikegami Yasuyuki , Nakamura Masatoshi
Published: December 2009

This paper describes a simulation model for a spray flash desalination system which makes fresh water from sea water by using the temperature difference between warm surface sea water and cool deep sea water. The spray flash desalination system can be modeled by using the energy conservation law and the mass conservation law. Simulation results of the model are compared with the experimental results and show the accuracy of the proposed simulation model. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(4): 9–17, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20975
1‐D‐Tin(II) Phenylchalcogenolato Complexes ∞1[Sn(EPh)2] (E = S, Se, Te) – Synthesis, Structures, Quantum Chemical Studies and Thermal Behaviour
Authors: Eichhöfer Andreas , Jiang Ji‐Jun , Sommer Heino , Weigend Florian , Fuhr Olaf , Fenske Dieter , Su Cheng‐Yong , Buth Gernot
Published: December 2009

A series of three 1‐D‐tin(II) phenylchalcogenolato complexes ∞1[Sn(EPh)2] (E = S, Se, Te) were synthesized in yields > 80 % by reaction of SnCl2 with two equivalents of PhESiMe3 in organic solvents. In the crystal the molecules form two different types of one‐dimensional chains. In ∞1[Sn(SPh)2] the tin atoms are distorted trigonal pyramidal coordinated by sulfur atoms (two bonds within a monomer and one longer bond between neighbored monomers), while in ∞1[Sn(EPh)2] (E = Se, Te) the tin atoms show contacts to two neighbored monomers leading to a fourfold coordination of the tin atoms by either selenium or tellurium atoms. The bond situation is discussed on the basis of density functional calculations. Thermal treatment mostly leads to the formation of the corresponding phase pure tin(II) chalcogenides however sublimation plays an increasing role ongoing from the tellurolato to the thiolato complex especially for the use of vacuum conditions. The investigation of the volatile cleavage products reveals the occurence of more complex reactions in the gas phase than the formal stoichiometric cleavage of EPh2 (E = S, Se, Te) with formation of SnE.
Hydrogen and Halogen Bonding in the Crystal Structure of a 1,3,5‐Substituted 2,4,6‐Triethylbenzene Consisting of Three Phenanthroline Units
Authors: Mazik Monika , Hartmann Andrè , Jones Peter G.
Published: December 2009

1,3,5‐Tris‐[N‐(1,10‐phenanthrolin‐2‐yl‐carbonyl)aminomethyl]‐2,4,6‐triethylbenzene (1) was synthesized and its crystal structure was examined. X‐ray structural analysis revealed the presence of hydrogen‐bonded water molecules as well as hydrogen‐ and halogen‐bonded chloroform molecules in the crystal structure of 1. The 1·H2O·CHCl3 associate is stabilized by N–H···O, O–H···N, O–H···O, C–H···O, and C–H···Cl hydrogen bonds as well as C–Cl···O, C–Cl···π, and C–Cl···Cl interactions. Particularly short C–H···O hydrogen bonds with H···O and C···O distances of 1.89 and 2.94 Å, respectively, are observed in the crystal structure. The H···O distance is approximately 30 % shorter than the sum of the van der Waals radii of involved atoms.
New Colours for Carotenoids – Synthesis of Pyran Polyenes
Authors: Øpstad Christer L. , Sliwka Hans‐Richard , Partali Vassilia
Published: December 2009

A new type of carotenoid has been synthesized with a 2H‐pyran ring placed in the polyene chain. This compound was successively elongated by Wittig reactions. The pyran‐carotenoids obtained show a significant increased λmax compared with carotenoids lacking the pyran ring. A further remarkable bathochromic shift was observed upon protonation to pyranium‐carotenoids. The pyranium ring is the distinctive feature of anthocyanidin dyes and has now become an internal part of carotenoids.
Graft linker immobilization for spatial control of protein immobilization inside fused microchips
Authors: Shirai Kentaro , Renberg Björn , Sato Kae , Mawatari Kazuma , Konno Tomohiro , Ishihara Kazuhiko , Kitamori Takehiko
Published: December 2009

Fused silica glass microchips have several attractive features for lab‐on‐a‐chip applications; they can be machined with excellent precision down to nanospace; are stable; transparent and can be modified with a range of silanization agents to change channel surface properties. For immobilization, however, ligands must be added after bonding, since the harsh bonding conditions using heat or hydrofluoric acid would remove all prior immobilized ligands. For spatial control over immobilization, UV‐mediated immobilization offers several advantages; spots can be created in parallel, the feature size can be made small, and spatial control over patterns and positions is excellent. However, UV sensitive groups are often based on hydrophobic chemical moieties, which unfortunately result in greater non‐specific binding of biomolecules, especially proteins. Here, we present techniques in which any –CHx (x=1,2,3) containing surface coating can be used as foundation for grafting a hydrophilic linker with a chemical anchor, a carboxyl group, to which proteins and amine containing molecules can be covalently coupled. Hence, the attractive features of many well‐known protein and biomolecule repelling polymer coatings can be utilized while achieving site‐specific immobilization only to pre‐determined areas within the bonded microchips.
Dry film microchips for miniaturised separations
Authors: Guijt Rosanne M. , Candish Esme , Breadmore Michael C.
Published: December 2009

In this work microfluidic devices were made from the dry film photoresist Ordyl SY330, characterised by optical and electron microscopy and used for electrophoretic separations. A simple and fast microfabrication process was developed for the fabrication of channels that are 50 μm wide and 30 μm in height, requiring only the use of an office laminator, a hot plate, an exposure source and mask and an electric drill to make four microdevices in less than 1 h. The optical properties of the photoresist were studied and the resist showed significant absorbance below 370 nm and 570–630 nm, and had an optical transmission of 80% between 400 and 550 nm. Fluorescence emission over the region of maximum transmission was low allowing these devices to be used for fluorescence detection at 488/512 nm. Electrophoretic separation of APTS and three derivatised sugars was performed in 20 mM phosphate buffer, pH 2.5 with efficiencies of the three sugars of 40 000 plates (2 100 000 plates/m) within 30 s at a field strength of 500 V/cm. The simple fabrication process also allowed microchannels to be easily filled with chromatography particles before sealing, avoiding the challenging task of slurry packing, and the potential of these devices for liquid chromatography was demonstrated by the extraction of fluorescein onto anion exchange particles.
Evaluation of microchip material and surface treatment options for IEF of allergenic milk proteins on microchips
Authors: Poitevin Martine , Shakalisava Yuliya , Miserere Sandrine , Peltre Gabriel , Viovy Jean‐Louis , Descroix Stephanie
Published: December 2009

The use of glass and PDMS microchips has been investigated to perform rapid and efficient separation of allergenic whey proteins by IEF. To decrease EOF and to limit protein adsorption, two coating procedures have been compared. The first one consists in immobilizing hydroxypropyl cellulose (HPC) and the second one poly(dimethylacrylamide‐co‐allyl glycidyl ether) (PDMA‐AGE). EOF limitation has been evaluated using frontal electrophoresis of a fluorescent marker of known effective mobility. EOF velocity was decreased by a factor about 100 and 30, respectively. pH gradient formation has been evaluated for each microchip using fluorescent pI markers. It was demonstrated that as expected a coating was essential to avoid pH gradient drift. Both coatings were efficient on glass microchips, but only PDMA‐AGE allowed satisfying focusing of pI markers on PDMS microchips. Fluorescent covalent and noncovalent labelings of milk proteins have been compared by IEF on slab‐gels. IEF separation of three major allergenic whey proteins [β‐lactoglobulin A (pI 5.25) and B (pI 5.35) and α‐lactalbumin (pI 4.2–4.5)] was performed in both microchips. Milk proteins were separated with better resolution and shorter analysis time than by classical CIEF. Finally, better resolutions for milk allergens separation were obtained on glass microchips.
A microfluidic device for characterizing the invasion of cancer cells in 3‐D matrix
Authors: Liu Tingjiao , Li Chunyu , Li Hongjing , Zeng Shaojiang , Qin Jianhua , Lin Bingcheng
Published: December 2009

A microfluidic device was developed for the study of directed invasion of cancer cells in 3‐D matrix with concentration gradient. This device consists of two parallel perfusion channels connected by two cell culture chambers. To mimic extracellular matrix (ECM), gelled basement membrane extract (BME) was used to support 3‐D distribution of breast cancer cells (MCF7) in cell culture chambers. A stable linear concentration gradient of epidermal growth factor (EGF) was generated across the chambers by continuous perfusion. Using the device, we investigated MCF7 cell invasion induced by different concentrations of EGF in 3‐D matrix. It was found that cancer cells responded to EGF stimulation with forming cellular protrusions and migrating towards high EGF concentration. We further investigated the anti‐invasion effect of GM 6001, a matrix metalloproteinase inhibitor. We identified that matrix metalloproteinase inhibition repressed both cellular protrusion formation and cell migration in 3‐D matrix. These findings suggest that EGF is able to induce MCF7 cell invasion in 3‐D extracellular matrix and this effect is dependent on proteolytic activity. This device is relatively simple to construct and operate. It should be a useful platform for elucidating the mechanism of cancer invasion and screening anti‐invasion drugs for cancer therapy.
Microchip CGE linked to immunoprecipitation as an alternative to Western blotting
Authors: Wenz Christian , Rüfer Andreas
Published: December 2009

A novel approach for protein identification is presented, which combines the specificity of an immunoprecipitation approach with the sensitivity of protein detection in microchip CGE. This method involves derivatization of the sample proteins with a fluorescent dye, target protein isolation with specific antibodies and Protein A coated magnetic beads, and automated sizing and quantification of the eluted samples on microchips. The performance of the new technique was demonstrated with glutathion‐S‐transferase‐ and polyHistidine‐tagged target proteins in an Escherichia coli background. A specific detection of target proteins was possible down to 0.001% or 1 ng target protein in a background of 100 μg E. coli protein. With this approach, proteins ranging from 10 to 220 kDa could be identified with a panel of different target‐specific antibodies. The reproducibility of the method was very similar to standard microchip CGE methods. In a direct comparison to Western blotting, a similar sensitivity and specificity of both techniques was observed. However, the new approach compares favorably to Western blotting in terms of time‐to‐result, usability and labor intensity, antibody consumption and access to quantitative data.
DNA manipulation by means of insulator‐based dielectrophoresis employing direct current electric fields
Authors: Gallo‐Villanueva Roberto C. , Rodríguez‐López Carlos E. , Díaz‐de‐la‐Garza Rocío I. , Reyes‐Betanzo Claudia , Lapizco‐Encinas Blanca H.
Published: December 2009

Electrokinetic techniques offer a great potential for biological particle manipulation. Among these, dielectrophoresis (DEP) has been successfully utilized for the concentration of bioparticles. Traditionally, DEP is performed employing microelectrodes, an approach with attractive characteristics but expensive due to microelectrode fabrication costs. An alternative is insulator‐based DEP, a method where non‐uniform electric fields are created with arrays of insulating structures. This study presents the concentration of linear DNA particles (pET28b) employing a microchannel, with an array of cylindrical insulating structures and direct current electric fields. Results showed manipulation of DNA particles with a combination of electroosmotic, electrophoretic, and dielectrophoretic forces. Employing suspending media with conductivity of 104 μS/cm and pH of 11.15, under applied fields between 500 and 1500 V/cm, DNA particles were observed to be immobilized due to negative dielectrophoretic trapping. The observation of DNA aggregates that occurred at higher applied fields, and dispersed once the field was removed is also included. Finally, concentration factors varying from 8 to 24 times the feed concentration were measured at 2000 V/cm after concentration time‐periods of 20–40 s. The results presented here demonstrate the potential of insulator‐based DEP for DNA concentration, and open the possibility for fast DNA manipulation for laboratory and large‐scale applications.
Temperature gradient focusing in miniaturized free‐flow electrophoresis devices
Authors: Becker Marco , Mansouri Abraham , Beilein Cornelia , Janasek Dirk
Published: December 2009

Temperature gradient focusing is a method to separate and focus any charged analytes even without accessible isoelectric point, and has been already widely used in CE. In this paper, we demonstrate the application of temperature gradient focusing to free‐flow electrophoresis. Besides focusing and separation experiments of proteins, the stability of the temperature gradient under flow conditions and the temperature dependence of fluorescence dyes have also been investigated.
Comparing polyelectrolyte multilayer‐coated PMMA microfluidic devices and glass microchips for electrophoretic separations
Authors: Currie Christa A. , Shim Joon Sub , Lee Se Hwan , Ahn Chong , Limbach Patrick A. , Halsall H. Brian , Heineman William R.
Published: December 2009

There is a continuing drive in microfluidics to transfer microchip systems from the more expensive glass microchips to cheaper polymer microchips. Here, we investigate using polyelectrolyte multilayers (PEM) as a coating system for PMMA microchips to improve their functionality. The multilayer system was prepared by layer‐to‐layer deposition of poly(diallyldimethylammonium) chloride and polystyrene sulfonate. Practical aspects of coating PMMA microchips were explored. The multilayer buildup process was monitored using EOF measurements, and the stability of the PEM was investigated. The performance of the PEM‐PMMA microchip was compared with those of a standard glass microchip and a PEM‐glass microchip in terms of EOF and separating two fluorescent dyes. Several key findings in the development of the multilayer coating procedure for PMMA chips are also presented. It was found that, with careful preparation, a PEM‐PMMA microchip can be prepared that has properties comparable – and in some cases superior – to those of a standard glass microchip.