bluuebunny/crossref_metadata_2025 huggingface dataset:
A Fast Method for pKa Determination by Capillary Electrophoresis
Authors: Fuguet Elisabet , Ràfols Clara , Bosch Elisabeth , Rosés Martí
Published: November 2009

In this article, we describe a recently developed capillary‐electrophoresis method for the determination of acidity constants and compare it with other existing methods. The new method is based on the use of an internal standard (compound similar in nature and pKa value to the analyte), and offers several benefits, since it has all the advantages of capillary electrophoresis. In addition, it is very fast, because the exact measure of the pH of the separation electrolytes is not needed, and only a few electrophoretic runs are required to perform a pKa determination. The acidity constants of some monoprotic weak acids and bases were determined by this fast method, yielding a very good agreement with literature values.
Kinetic and Thermodynamic Solubility Values of Some Bioactive Compounds
Authors: Shoghi Elham , Fuguet Elisabet , Ràfols Clara , Bosch Elisabeth
Published: November 2009

Thermodynamic solubility is a decisive physicochemical property in drug development. The Chasing Equilibrium method offers an alternative to the classical procedures to measure the solubility of compounds with acid–base properties. The method is fast and yields accurate results. In this work, the solubility of several compounds including acids and bases was determined through the Chasing Equilibrium approach. A study of experimental conditions in terms of sample weight was performed to measure solubilities. The study shows that only a limited range of weights, depending on the nature and solubility of the compounds, is adequate to obtain reliable results.
Transporters – The View from Industry
Authors: Kohl Christopher
Published: November 2009

The involvement of transport proteins in the disposition of drugs is receiving much attention of the scientific community. Recently, researchers from academia have surmised that drug transport rather than passive diffusion is the regular mechanism for molecules to cross cell membranes. On bare face value, however, sound evidence of the impact of transport proteins on clinical pharmacokinetics has been a trickle rather than a stream of convincing studies during the last decade, in stark contrast to the number of in vitro studies published. Progress in this area may have been impeded by a number of factors. Only a limited number of small‐molecule drugs fall within the physicochemical property space (i.e., high hydrophilicity and low passive permeability) that makes them predestined as transport protein substrates without other pharmacokinetic processes (e.g., passive diffusion, metabolism, nonspecific binding to tissue proteins) blurring the picture. The vast majority of drug molecules are lipophilic enough to be amenable to passive diffusion across cell membranes and to undergo metabolism to some extent. In these cases, clinical evidence relies heavily on the observation of pharmacokinetic drug–drug interactions not readily explained by the interference with drug metabolizing enzymes. Given the circumstances outlined above, it is not surprising that, based upon clinical observations, the final assessment as to the overall relevance of drug transport for clinical pharmacokinetics is still pending.
Influence of Ionization State on the Activation of Temocapril by hCES1: A Molecular‐Dynamics Study
Authors: Vistoli Giulio , Pedretti Alessandro , Mazzolari Angelica , Bolchi Cristiano , Testa Bernard
Published: November 2009

Temocapril is a prodrug whose hydrolysis by carboxylesterase 1 (CES1) yields the active ACE inhibitor temocaprilat. This molecular‐dynamics (MD) study uses a resolved structure of the human CES1 (hCES1) to investigate some mechanistic details of temocapril hydrolysis. The ionization constants of temocapril (pK1 and pK3) and temocaprilat (pK1, pK2, and pK3) were determined experimentally and computationally using commercial algorithms. The constants so obtained were in good agreement and revealed that temocapril exists mainly in three ionic forms (a cation, a zwitterion, and an anion), whereas temocaprilat exists in four major ionic forms (a cation, a zwitterion, an anion, and a dianion). All these ionic forms were used as ligands in 5‐ns MS simulations. While the cationic and zwitterionic forms of temocapril were involved in an ion‐pair bond with Glu255 suggestive of an inhibitor behavior, the anionic form remained in a productive interaction with the catalytic center. As for temocaprilat, its cation appeared trapped by Glu255, while its zwitterion and anion made a slow departure from the catalytic site and a partial egress from the protein. Only its dianion was effectively removed from the catalytic site and attracted to the protein surface by Lys residues. A detailed mechanism of product egress emerges from the simulations.
Engineering Allosteric Regulation into Biological Catalysts
Authors: Fastrez Jacques
Published: November 2009

Enzymes and ribozymes constitute two classes of biological catalysts. The activity of many natural enzymes is regulated by the binding of ligands that have different structures than their substrates; these ligands are consequently called allosteric effectors. In most allosteric enzymes, the allosteric binding site lies far away from the active site. This implies that communication pathways must exist between these sites. While mechanisms of allosteric regulation were developed more than forty years ago, they continue to be revisited regularly. The improved understanding of these mechanisms has led in the past two decades to projects to transform several unregulated enzymes into allosterically regulated ones either by rational design or directed evolution techniques. More recently, ribozymes have also been the object of similar successful engineering efforts. In this review, after briefly summarising recent progress in the theories of allosteric regulation, several strategies to engineer allosteric regulations in enzymes and ribozymes are described and compared. These redesigned biological catalysts find applications in a variety of areas.
Induced‐Fit Binding of π‐Electron‐Donor Substrates to Macrocyclic Aromatic Ether Imide Sulfones: A Versatile Approach to Molecular Assembly
Authors: Colquhoun Howard M. , Zhu Zhixue , Williams David J. , Drew Michael G. B. , Cardin Christine J. , Gan Yu , Crawford Andrew G. , Marder Todd B.
Published: November 2009

Novel macrocyclic receptors that bind electron‐donor aromatic substrates through π‐stacking donor–acceptor interactions are obtained by cycloimidisation of an amine‐functionalised aryl ether sulfone with pyromellitic and 1,4,5,8‐naphthalenetetracarboxylic dianhydrides. These macrocycles can form complexes with a wide variety of π‐donor substrates, including tetrathiafulvalene, naphthalene, anthracene, pyrene, perylene and functional derivatives of these polycyclic hydrocarbons. The resulting supramolecular assemblies range from simple 1:1 complexes to [2]‐ and [3]pseudorotaxanes and even (as a result of crystallographic disorder) an apparent polyrotaxane. Direct five‐component self‐assembly of a metal‐centred [3]pseudorotaxane is also observed on complexation of a macrocyclic ether imide with 8‐hydroxyquinoline in the presence of palladium(II) ions. Binding studies in solution were carried out by using 1H NMR and UV/Vis spectroscopy, and the stoichiometries of binding were confirmed by Job plots based on the charge‐transfer absorption bands. The highest association constants were found for strong π‐donor guests with large surface areas, notably perylene and 1‐hydroxypyrene, for which Ka values of 1.4×103 and 2.3×103 M−1, respectively, were found. Single‐crystal X‐ray analyses of the receptors and their derived complexes reveal large induced‐fit distortions of the macrocyclic frameworks as a result of complexation. These structures provide compelling evidence for the existence of strong attractive forces between the electronically complementary aromatic π systems of host and guest.
Expanding the Scope of Enantioselective FerroPHANE‐Promoted [3+2] Annulations with α,β‐Unsaturated Ketones
Authors: Pinto Nathalie , Neel Mathilde , Panossian Armen , Retailleau Pascal , Frison Gilles , Voituriez Arnaud , Marinetti Angela
Published: November 2009

The planar chiral 2‐phospha[3]ferrocenophane I has been shown to be the first efficient nucleophilic organocatalyst for the enantioselective synthesis of cyclopentenylphosphonates, through [3+2] cyclizations between diethyl allenylphosphonate and α,β‐unsaturated ketones. The same catalyst has also been applied to the highly enantioselective [3+2] cyclizations of allenic esters with dibenzylideneacetone and analogous bis‐enones, leading to functionalised cyclopentenes with either monocyclic or spirocyclic structures (ee 84–95 %). It has been shown that the residual enone functions in the resulting cyclopentenes can be involved in subsequent cyclization steps to afford unprecedented C2‐symmetric bis‐cyclopentenylketones. In order to provide insight into the behaviour of FerroPHANE I as a chiral catalyst in [3+2] cyclisations, the energetically most favoured isomers of the key phosphine‐allene adduct have been calculated by DFT methods. Factors likely to control the chiral induction process are highlighted.
Macrocyclic DNA‐Mismatch‐Binding Ligands: Structural Determinants of Selectivity
Authors: Granzhan Anton , Largy Eric , Saettel Nicolas , Teulade‐Fichou Marie‐Paule
Published: November 2009

A collection of 15 homodimeric and 5 heterodimeric macrocyclic bisintercalators was prepared by one‐ or two‐step condensation of aromatic dialdehydes with aliphatic diamines; notably, the heterodimeric scaffolds were synthesized for the first time. The binding of these macrocycles to DNA duplexes containing a mispaired thymine residue (TX), as well as to the fully paired control (TA), was investigated by thermal denaturation and fluorescent‐intercalator‐displacement experiments. The bisnaphthalene derivatives, in particular, the 2,7‐disubstituted ones, have the highest selectivity for the TX mismatches, as these macrocycles show no apparent binding to the fully paired DNA. By contrast, other macrocyclic ligands, as well as seven conventional DNA binders, show lesser or no selectivity for the mismatch sites. The study demonstrates that the topology of the ligands plays a crucial role in determining the mismatch‐binding affinity and selectivity of the macrocyclic bisintercalators.
Quinoidal Oligothiophenes: Towards Biradical Ground‐State Species
Authors: Ponce Ortiz Rocío , Casado Juan , Rodríguez González Sandra , Hernández Víctor , López Navarrete Juan T. , Viruela Pedro M. , Ortí Enrique , Takimiya Kazuo , Otsubo Tetsuo
Published: November 2009

A family of quinoidal oligothiophenes, from the dimer to the hexamer, with fused bis(butoxymethyl)cyclopentane groups has been extensively investigated by means of electronic and vibrational spectroscopy, electrochemical measurements, and density functional calculations. The latter predict that the electronic ground state always corresponds to a singlet state and that, for the longest oligomers, this state has biradical character that increases with increasing oligomer length. The shortest oligomers display closed‐shell quinoidal structures. Calculations also predict the existence of very low energy excited triplet states that can be populated at room temperature. Aromatization of the conjugated carbon backbone is the driving force that determines the increasing biradical character of the ground state and the appearance of low‐lying triplet states. UV/Vis, Raman, IR, and electrochemical experiments support the aromatic biradical structures predicted for the ground state of the longest oligomers and reveal that population of the low‐lying triplet state accounts for the magnetic activity displayed by these compounds.
Cross‐Reactive Sensor Arrays for the Detection of Peptides in Aqueous Solution by Fluorescence Spectroscopy
Authors: Rochat Sébastien , Gao Jie , Qian Xuhong , Zaubitzer Friederike , Severin Kay
Published: November 2009

A simple but powerful method for the sensing of peptides in aqueous solution has been developed. The transition‐metal complexes [PdCl2(en)], [{RhCl2Cp*}2], and [{RuCl2(p‐cymene)}2] were combined with six different fluorescent dyes to build a cross‐reactive sensor array. The fluorescence response of the individual sensor units was based on competitive complexation reactions between the peptide analytes and the fluorescent dyes. The collective response of the sensor array in a time‐resolved fashion was used as an input for multivariate analyses. A sensor array comprised of only six metal–dye combinations was able to differentiate ten different dipeptides in buffered aqueous solution at a concentration of 50 μM. Furthermore, the cross‐reactive sensor could be used to obtain information about the identity and the quantity of the pharmacologically interesting dipeptides carnosine and homocarnosine in a complex biological matrix, such as deproteinized human blood serum. The sensor array was also able to sense longer peptides, which was demonstrated by differentiating mixtures of the nonapeptide bradykinin and the decapeptide kallidin.
Shifting Paradigms: Electrostatic Interactions and Covalent Bonding
Authors: Jacobsen Heiko
Published: November 2009

The role of electrostatic interactions in covalent bonding of heavier main group elements has been evaluated for the exemplary set of molecules X2H2(X=C, Si, Ge, Sn, Pb). Density functional calculations at PBE/QZ4P combined with energy decomposition procedures and kinetic energy density analyses have been carried out for a variety of different structures, and two factors are responsible for the fact that the heavier homologues of acetylene exhibit doubly hydrogen‐bridged local minimum geometries. For one, the extended electronic core with at least one set of p orbitals of the Group 14 elements beyond the first long period is responsible for favorable electrostatic E–H interactions. This electrostatic interaction is the strongest for the isomer with two bridging hydrogen atoms. Secondly, the H substituent does not posses an electronic core or any bonding‐inactive electrons, which would give rise to a significant amount of Pauli repulsion, disfavoring the doubly bridged isomer. When one of two criteria is not met the unusual doubly bridged structure no longer constitutes the energetically preferred geometry. The bonding model is validated in calculations of different structures of Si2(CH3)2.
Dynamic capabilities and e‐service
Authors: Rolland Erik , Patterson Raymond A. , Ward Keith F.
Published: November 2009

The rapid, pervasive growth of Internet use for business purposes has had a noticeable effect on numerous firms' business strategies. This type of perturbation among competitors results in a more dynamic market. To be successful in such a market often requires a firm to reexamine how it competes. In recent years, two strategic management theories—the resource‐based view (RBV) and the dynamic capabilities theory (DCT)—have been advanced by proponents as being the key to developing successful competitive advantage. We argue that the DCT is a logical extension of the RBV. Operationalization has been a critical issue for both theories, and this paper fills a gap in the literature by offering a method of operationalizing dynamic capabilities. Copyright © 2009 ASAC. Published by John Wiley & Sons, Ltd.
Droplet size and viscosity of tackifier emulsions formed via phase inversion
Authors: Song Daoyun , Zhang Wu , Gupta Rakesh K. , Melby Earl G.
Published: November 2009

Tackifier dispersions used in pressure‐sensitive adhesives are made by phase inverting an aqueous rosin ester emulsion. The recipe also includes rosin acid and potassium hydroxide which react to form a surfactant. The amount of surfactant available plays a key role in determining dispersion properties. As the surfactant concentration increases, the point of phase inversion is delayed to larger dispersed phase concentrations. This also results in excess dispersant in the liquid phase and a narrower particle size distribution, even though the droplet size remains relatively unchanged.
Stability of hydrolase enzymes in ionic liquids
Authors: Hernández‐Fernández F. J. , Ríos A. P. de los , Tomás‐Alonso F. , Gómez D. , Víllora G.
Published: November 2009

In this work we attempted to evaluate the stability of penicillin G acylase (PGA) from Escherichia coli in their native form and free Candida antarctica lipase B (CaLB) in ionic liquids (ILs) at low water content. The hydrolysis of penicillin G to 6‐aminopenicillanic acid (6‐APA), and phenyl acetic acid (PAA) catalysed by PGA and the synthesis of butyl butyrate from vinyl butyrate and 1‐butanol catalysed by CaLB were chosen as activity tests. The influence of these new solvents on enzyme stability was studied by incubating the enzyme (PGA or CaLB) in ILs based on dialkylimidazolium cations associated with perfluorinated and dicyanamide anions at a given temperature. Stability studies indicate that CaLB and PGA exhibited greater stability in water‐immiscible ILs than in water‐miscible ILs. Specifically, native PGA shows greater stability in IL media than in organic solvents. For example, a half‐life time of 23 h was obtained in 1‐ethyl‐3‐methylimidazolium bis{(trifluoromethyl)sulfonyl}imide, $[{\rm emim}^ + ][{\rm NTf}_2^ - ]$, which was about 2000‐fold higher than that in 2‐propanol. The higher half‐life time of CaLB was observed in $[{\rm omim}^ + ][{\rm PF}_6^ - ]$ (t1/2 = 84 h).
Effect of weathering on oil sands processability
Authors: Ren Sili , Zhao Hongying , Dang‐Vu Trong , Xu Zhenghe , Masliyah Jacob H.
Published: November 2009

Effect of weathering on oil sand processability was studied using a good processing ore, a laboratory weathered ore and a naturally weathered ore. The laboratory weathered ore was prepared by weathering the good processing ore in an oven under controlled conditions to study the nature of ore weathering. It was found that the bitumen recovery, bitumen flotation rate, and bitumen froth quality were greatly reduced due to ore weathering. It was also observed that the fresh bitumen coating on a silicon surface could recede and liberate from the silicon surface easily even in a warm water of 35°C. However, after weathering of the bitumen coating, its liberation became more difficult and effective liberation of bitumen from the silicon surface could only occur at higher temperature of 65°C. The current study further confirms that weathering enhanced adhesion of bitumen with solids, causing difficulties for bitumen liberation from sand grains and hence poor processability of weathered ores.
Adsorption kinetics of cadmium ions onto powdered corn cobs
Authors: Ismail A. , Adie D. B. , Oke I. A. , Otun J. A. , Olarinoye N. O. , Lukman S. , Okuofu C. A.
Published: November 2009

Environmental pollution caused by the presence of toxic materials such as cadmium is becoming global problem and concern. This paper presents a report on kinetics of Cd2+ removal from aqueous solutions through adsorption using powdered corn cobs (PCC). Corn cobs were collected from a selected location, washed to remove sand, air dried, ground and sieved into different particle sizes. The selected properties of PCC were determined using acid digestion method. Adsorption capacities through kinetics of Cd2+ removal from synthetic solutions, typical raw water and domestic‐institutional wastewater were studied. Effects of pH, PCC particle size, initial concentration of Cd2+ and temperature on adsorption capacities were monitored through pseudo first‐ and second‐order models, Elovich and intraparticle diffusion models to present adsorption rate parameters.

The study revealed that PCC contained 86.89% volatile solids, had 4.56% acid solubility, 0.52 water solubility and 2.33% ash content. PCC removed Cd2+ from aqueous solutions (synthetic, raw water, and wastewater). The relationship between time and concentration of Cd2+ remaining in the solution followed exponential functions with squared correlation coefficient ranging from 0.9928 to 0.9993, 0.8701 to 0.9284, and 0.8514 to 0.9290 for synthetic solution, raw water, and typical domestic‐institutional wastewater, respectively. Mechanism of cadmium adsorption onto PCC was in two separate stages linear portions in the first parts, while the final parts are curves indicating intraparticle diffusion. It was concluded that PCC is an effective adsorbent for Cd2+ removal. The estimated production cost was 0.068 USD as against 0.50, 2.12, and 3.12 USD for producing adsorbents from empty fruit bunches; pencom shell and sugar cane based activated carbons, respectively.
Transient Cardiac Ballooning—The Syndrome
Authors: Gupta Raghav , Sech Candice , Lazzara Ralph
Published: November 2009

Transient cardiac ballooning is usually a reversible clinical entity. A patient typically presents with chest pain, electrocardiogram (ECG) abnormalities like ST‐segment elevation (most commonly reported) or depression, and elevated cardiac enzymes, but has no or nonobstructive coronary artery disease. Left ventriculography reveals transient akinesis of the involved portion of the myocardial wall with compensatory hyperkinesis of the remaining myocardium, leading to ballooning of the noncontracting myocardial wall during systole. Acute regional myocardial dysfunction ensues, which normalizes on average within 1 to 6 weeks. The hypotheses for these pathophysiologic changes range from direct cardiac myocyte injury to postischemic myocardial stunning to neurotransmitter actions. The objective of this article is to present a succinct description of a small case series accompanied with various recently reported presentations and morphology by left ventriculogram and a detailed review of available data on underlying pathophysiology. In addition, a discussion on current diagnostic guidelines, treatment, prognosis, and potential future investigations is included. Copyright © 2009 Wiley Periodicals, Inc.
Percutaneous Transluminal Angioplasty and Stenting for Pulmonary Stenosis Due to Takayasu's Arteritis: Clinical Outcome and Four‐year Follow‐up
Authors: Qin Luo , Hong‐Liang Zhang , Zhi‐Hong Liu , Chang‐Ming Xiong , Xin‐Hai Ni
Published: November 2009

Background

Percutaneous transluminal angioplasty and stent implantation for stenotic lesions of renal arteries and other branches of the aorta in Takayasu's arteritis have been reported to show good outcomes. However, this form of therapy has been reported in few cases with pulmonary artery involvement.

Hypothesis

The aim of this study was to evaluate the role of this interventional treatment for pulmonary stenosis due to Takayasu's arteritis.

Methods

A total of 4 patients (3 female and 1 male, ages 30–40 yrs) with Takayasu's pulmonary arteritis underwent percutaneous transluminal balloon angioplasty and stent implantation and were followed up for 1 to 4 years.

Results

One patient underwent balloon angioplasty alone, 3 patients underwent balloon angioplasty and stent implantation. The stenoses were relieved acutely, oxygen saturation improved immediately due to improvement in lung perfusion and relief of dyspnea. The pressure gradient fell from 58.3 ± 8.7 mm Hg to 14 ± 3.2 mm Hg and mean pulmonary arterial pressure decreased from 48.5 ± 12.0 mm Hg to 37.3 ± 6.0 mm Hg. At a follow‐up period of 34.5 ± 15.8 months, the patient with balloon angioplasty alone developed a recurrence of symptoms 18 months after the procedure. The other 3 patients continued to be asymptomatic and the stent remained patent without restenosis after the procedure.

Conclusion

Percutaneous transluminal angioplasty and stent implantation is a safe and effective treatment in patients with pulmonary stenosis caused by Takayasu's arteritis. Copyright © 2009 Wiley Periodicals, Inc.
Acute Coronary Syndromes: Selective vs Early Invasive Strategies
Authors: Boden William E. , Gupta Vipul
Published: November 2009

Recommendations in the 2007 update of the American College of Cardiology/American Heart Association guidelines for patients with non–ST‐elevation myocardial infarction (NSTEMI) provide considerable latitude regarding treatment choices and care pathways. Nevertheless, as accumulating evidence leads to increased recommendations for early invasive strategies, more patients are likely to receive care that falls short of recommendations. While tailoring pharmacotherapy to optimize the risk/benefit ratio for individual patients remains essential, it becomes increasingly important that care paradigms be prospectively defined. To facilitate this goal, we examined key differences between the 2002 and 2007 guidelines and explored data underlying changed recommendations for periprocedural pharmacotherapy. Copyright © 2009 Wiley Periodicals, Inc.
Clinical Prognostic Significance of Plasma Cystatin C Levels among Patients With Acute Coronary Syndrome
Authors: Ge Changjiang , Ren Fang , Lu Shuzheng , Ji Fengqing , Chen Xin , Wu Xiaofan
Published: November 2009

Background

This article aims to investigate the changes of plasma cystatin C concentration (PcyC), and to evaluate the relationship between PcyC and acute coronary syndrome.

Methods

A total of 126 consecutive patients with coronary artery disease (CAD) were enrolled in this study, consisting of 34 patients with stable angina pectoris (SAP), 56 patients with unstable angina pectoris (UAP), 36 patients with acute myocardial infarction (AMI), and 34 healthy subjects as controls. Plasma cystatin C, high sensitivity C‐reactive protein (hs‐CRP), total cholesterol (TC), low‐density lipoprotein cholesterol (LDL‐C), high‐density lipoprotein cholesterol (HDL‐C), triglycerides (TG), and uric acid (UA) in all subjects were determined. All patients were followed up for 6 months and adverse cardiovascular events were recorded.

Results

Plasma cystatin C was elevated in CAD. Cystatin C levels were significantly higher in UAP patients than those in SAP patients and controls (2013.83 ± 633.85 ng/mL vs 1348.41 ± 369.62 ng/mL and 1509.99 ± 408.65 ng/mL, P < 0.05), but were much lower than those in AMI patients (2013.83 ± 633.85 ng/mL vs 2873.55 ± 1149.48 ng/mL, P < 0.05). Patients with AMI also exhibited significantly higher cystatin C levels than SAP patients and the control group (2873.55 ± 1149.48 ng/mL vs 1348.41 ± 369.62 ng/mL and 1509.99 ± 408.65 ng/mL, P < 0.01). Much higher hs‐CRP concentrations were found in UAP patients (1.58 ± 2.81 mg/L, P < 0.05) and AMI patients (20.68 ± 18.98 mg/L, P < 0.01). Cystatin C was positively and significantly correlated with age, hs‐CRP, white blood cells (WBC), creatinine, and UA (r > 0, P < 0.05), whereas a significantly negative correlation was observed with HDL‐C (r = − 0.227, P < 0.05). These coefficients were clearly high for creatinine (r = + 0.612) and WBC (r = + 0.459). During the 6 month follow‐up, 26 patients were found with adverse cardiovascular events and had significantly higher cystatin C levels than the 22 control patients at admission (2356.73 ± 897.64 ng/mL vs 1469.51 ± 574.83 ng/mL, P < 0.01).

Conclusions

Cystatin C plays an important role in the development of CAD and PcyC is a strong predictor for risk of cardiovascular events. Copyright © 2009 Wiley Periodicals, Inc.
Bandgap Modulation in Efficient n‐Thiophene Absorbers for Dye Solar Cell Sensitization
Authors: Barea Eva Mª , Caballero Rubén , Fabregat‐Santiago Francisco , De La Cruz Pilar , Langa Fernando , Bisquert Juan
Published: November 2009

Five new sensitizers for dye sensitized solar cells have been designed consisting of conjugated thienylenevinylene units threaded with alkyl chains to improve solubility and cyanoacetic acid as anchoring group. The conjugation length was increased from 2 to 6 thienylenevinylene units, which resulted in a red‐shift of the optical absorption of the dyes from 550 to 750 nm, improving the spectral overlap with the solar spectrum. The photovoltaic performance of these dyes as sensitizers in mesoporous TiO2 solar cells shows a clear correlation of increasing photocurrent with the extension of the conjugation up to an optimal length. Further extension of the conjugation increases the absorption but additional effects like self‐quenching or recombination processes reduce the photocurrent and photovoltages and consequently the overall efficiency of the DSC.
Ortho‐Dichlorobenzene Doped with Terrylene—a Highly Photo‐Stable Single‐Molecule System Promising for Photonics Applications
Authors: Gorshelev Alexey A. , Naumov Andrei V. , Eremchev Ivan Yu. , Vainer Yury G. , Kador Lothar , Köhler Jürgen
Published: November 2009

The study of a new dye‐matrix system—quickly frozen ortho‐dichlorobenzene weakly doped with terrylene—via single‐molecule (SM) spectroscopy is presented. The spectral and photo‐physical properties, dynamics, and temperature broadening of SM spectra at low temperatures are discussed. The data reveal a broad inhomogeneous distribution, which indicates a high degree of matrix inhomogeneities, but at the same time, huge fluorescence emission rates and extraordinary SM spectral and photochemical stability with almost complete absence of blinking and bleaching. These unusual properties render the new system a promising candidate for applications in photonics, for example, for delivering single photons on demand.
Initial cytoplasmic and phagosomal consequences of human neutrophil exposure to Staphylococcus epidermidis
Authors: Bernardo John , Long Heidi J. , Simons Elizabeth R.
Published: November 2009

Microorganisms are recognized by specific phagocyte surface receptors. Liganded receptors then signal a series of events leading to phagocytosis and destruction of the organism by oxidative, lytic, and associated processes. Some organisms, such as Mycobacterium tuberculosis (Mtb), Cryptococcus neoformans (Cf), and others, evade such destruction, surviving and sometimes multiplying within the phagosome to later cause disease. To study such evasion, we developed protocols which permit simultaneous kinetic measurement of early cytoplasmic signaling and of phagosomal pH (pHp) and oxidative burst, on a cell‐by‐cell basis, of polymorphonuclear (PMN) leukocytes exposed to fluorescently labeled, nonpathogenic Staphylococcus epidermidis (Se). The availability of a new, highly sensitive pH probe, pHrodo™, permits observation of increasing pHp. Simultaneous labeling of the organism, applicable to any phagocyte target, with a probe insensitive to pH and oxidative species, such as AlexaFluor350™, permits distinction between binding and functional responses to it by ratioing fluorescences. Addition of an extracellular‐specific quencher (Trypan blue) permits distinction between bound and phagosome‐enclosed targets, so that conditions within the closed phagosome can be studied. We found that opsonization is required for functional activation of PMN by Se, that the organism causes early alkalinization of the phagosome (in contrast to Cf which hyperacidifies it), and that extracellular Ca2+ is not required for cytoplasmic Ca2+ signaling but contributes markedly to binding of Se to PMN and to ensuant bactericidal functions. These findings lead to a new approach to the study of select organisms, like Cf and Mtb, which evade killing by manipulating the phagosomal environment. © 2009 International Society for Advancement of Cytometry
Comparison of p16INK4a and ProEx™ C immunostaining on cervical ThinPrep® cytology and biopsy specimens
Authors: Oberg Trynda N. , Kipp Benjamin R. , Vrana Julie A. , Bartholet Mary K. , Fales Colleen J. , Garcia Rocio , McDonald Ashley N. , Rosas Brittany L. , Henry Michael R. , Clayton Amy C.
Published: November 2009

ProEx™ C and p16INK4a staining of cytology/histology specimens have recently been explored to help distinguish high‐grade squamous intraepithelial lesions (HSIL) from benign mimics. The goal of this study was to evaluate the performance characteristics of p16 and ProEx C in tissue and patient matched ThinPrep® liquid‐based cytology specimens. Residual cervical ThinPrep cytology specimens and tissue blocks (N = 64) from 63 patients were stained with p16 and ProEx C. Review of immunostained material, Papanicolaou and H&E stained slides was performed by two cytopathologists. The cytology slides were evaluated for the presence or absence of squamous atypia as well as immunoreactivity. Histologic specimens were interpreted as negative, indeterminate, or positive for each immunostain. There was 86% agreement (55/64) between the p16 and ProEx C stains on tissue specimens. Eleven specimens were interpreted as positive for both stains. All had a low‐ or high‐grade squamous lesion on the corresponding H&E section. ProEx C was able to identify four low‐grade squamous intraepithelial lesion specimens that were interpreted as negative by p16. All four HSIL specimens demonstrated p16 and ProEx C staining. However, 84% of cytology negative specimens demonstrated false‐positive staining. Clinical utilization of both stains, combined with morphologic features, may be beneficial for confirming HSIL on histologic specimens. ProEx C and/or p16 immunostains may lead to a false‐positive result in cytology specimens due to staining of normal appearing cells. Diagn. Cytopathol. 2010;38:564–572. 2009 Wiley‐Liss, Inc.
A rare case of pulmonary cryptococcal inflammatory myofibroblastic tumor diagnosed by fine needle aspiration cytology
Authors: Kushner Yael B. , Brimo Fadi , Schwartzman Kevin , Auger Manon
Published: November 2009

In a recent outbreak in British Columbia (BC), Canada, Cryptococcus gattii, a rare species of Cryptococcus, was noted to affect primarily immunocompetent hosts and cause limited pulmonary or CNS disease. We herein report a rare case of a pulmonary inflammatory myofibroblastic tumor caused by a Cryptococcus infection, presumed to be of the gattii species, in a 20‐year‐old immunocompetent college student from Vancouver, BC who presented with a large lung mass. The diagnosis was first made on the fine needle aspirate (FNA) material and was confirmed on the concurrent histologic core biopsy. Cryptococcal inflammatory myofibroblastic tumors have been reported, but neither in the lung nor in the setting of an immunocompetent host. Pulmonary cryptococcosis should therefore be considered in the differential diagnosis of a lung mass, even in an immunocompetent host, especially if the clinical history reveals recent travel to British Columbia where Cryptococcus gattii is endemic. Diagn. Cytopathol. 2010. © 2009 Wiley‐Liss, Inc.
Inkjet Printing of Water “Soluble” Doped ZnS Quantum Dots
Authors: Small Aaron C. , Johnston James H. , Clark Noel
Published: November 2009

Water‐soluble‐doped ZnS quantum dots were synthesised and formulated for inkjet printing. The quantum dots were then inkjet‐printed onto a variety of substrates, including photo quality inkjet paper, cotton fabric, PET film, and glass. Of these substrates, only inkjet printing of doped ZnS quantum dots on photo‐quality inkjet paper and cotton fabric produced a photoluminescent print. The materials were characterised using a number of methods, including profilometer measurements, photoluminescence spectroscopy (PL), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and viscosity measurements. On excitation with UV light, a photoluminescence emission of approximately 600 nm was observed.
Neutral Trinuclear Palladium(II) Metallocycles with Mixed Phosphane/Pyridine‐4‐thiolato Ligands and Their Catalytic Tests in Suzuki–Miyaura Coupling Reactions
Authors: Wang Hui , Zhong Rui , Guo Xu‐Qing , Feng Xiao‐Yan , Hou Xiu‐Feng
Published: November 2009

Three neutral trinuclear palladium(II) complexes [Ph3PPdCl(μ‐4‐PyS)]3 (1), [Cy3PPdCl(μ‐4‐PyS)]3 (2) and [(PhO)3PPdCl(μ‐4‐PyS)]3 (3) (4‐PyS = pyridine‐4‐thiolate) were self‐assembled from corresponding metal fragments [R3PPdCl2]2 with lithium pyridine‐4‐thiolate (PySLi). The crystal structure reveals that complex 1 possesses a triangular macrocyclic structure in which the distances of Pd(1)···Pd(2), Pd(2)···Pd(3) and Pd(3)···Pd(1) are 7.764, 7.684 and 7.944 Å, respectively. An equilibrium between trinuclear complex 1 and mononuclear complex (Ph3P)2PdCl(4‐PyS) (4) in solution through coordination and de‐coordination of the PPh3 ligand is confirmed by 31P NMR spectroscopy. A comparative study on the Suzuki–Miyaura coupling reaction showed that complexes 1 and 2 are more active precatalysts than [R3PPdCl2]2 complexes without a PyS group.
Dye‐Sensitized Solar Cells Based on a Novel Fluorescent Dye with a Pyridine Ring and a Pyridinium Dye with the Pyridinium Ring Forming Strong Interactions with Nanocrystalline TiO2 Films
Authors: Ooyama Yousuke , Inoue Shogo , Asada Risa , Ito Genta , Kushimoto Kohei , Komaguchi Kenji , Imae Ichiro , Harima Yutaka
Published: November 2009

As new‐type donor–acceptor π‐conjugated dyes capable of forming a strong interaction between the electron‐acceptor moiety of the sensitizers and a TiO2 surface, fluorescent dye OH11 and pyridinum dye OH12 with a pyridine and pyridinium ring as the electron‐accepting group, respectively, have been designed and synthesized as photosensitizers for use in dye‐sensitized solar cells (DSSCs). The fluorescent dye OH11 exhibits an absorption band at around 410 nm and a fluorescence band at around 530 nm. On the other hand, the pyridinum dye OH12 shows an absorption maximum at around 560 nm, assigned to a strong intramolecular charge‐transfer excitation from the dibutylamino group to the pyridinium ring. The short‐circuit photocurrent densities of the DSSCs prepared by using OH11 and OH12 are 4.33 and 1.74mA cm–2, and the solar energy‐to‐electricity conversion yields are 1.33 and 0.51 %, respectively, under simulated solar light [AM (air mass) 1.5, 100 mW cm–2]. The open‐circuit photovoltage for OH11 (525 mV) is higher than that of OH12 (444 mV). The effects of the configuration of the dyes on the TiO2 surface and of their chemical structures on the photovoltaic performances are discussed on the basis of semi‐empirical molecular orbital calculations (AM1 and INDO/S), spectral analyses and cyclic voltammetry.
Spectroscopic Investigation of the Europium(3+) Ion in a New ZnY4W3O16 Matrix
Authors: Tomaszewicz Elżbieta , Guzik Malgorzata , Cybińska Joanna , Legendziewicz Janina
Published: November 2009

A new Zn and Eu tungstate was characterized by spectroscopic techniques. This tungstate, of the formula ZnEu4W3O16, crystallized in the orthorhombic system and was synthesized by a solid‐state reaction. It melts incongruently at 1330°. The luminescent properties, including excitation and emission processes, luminescent dynamics, and local environments of the Eu3+ ions in ZnEu4W3O16 and ZnY4W3O16 : Eu3+ diluted phases (1, 5, and 10 mol‐% of Eu3+ ion) were studied basing on the f6‐intraconfigurational transitions in the 250–720 nm spectral range. The excitation spectra of this system (λem 615 and 470 nm) show broad bands with maxima at 265 and 315 nm related to the ligand‐to‐metal charge‐transfer (LMCT) states. The emission spectra under excitation at the O→W (265 nm) and O→Eu3+ (315 nm) LMCT states present the blue‐green emission bands. The emission of tungstate groups mainly originate from the charge‐transfer state of excited 2p orbitals of O2− to the empty orbitals of the central W6+ ions. On the other hand, in the emission of the Eu3+ ions, both the charge transfer from O2− to Eu3+ and the energy transfer from W6+ ions to Eu3+ are involved. The emission spectra under excitation at the 7F0→5L6 transition of the Eu3+ ion (394 nm) of ZnY4W3O16 : Eu3+ diluted samples show narrow emission lines from the 5D3, 5D2, and 5D1 emitting states. The effect of the active‐ion (Eu3+) concentration on the colorimetric characteristic of the emissions of the compound under investigation are presented.
The Photochemical Behavior of the Uranyl Ion (UO$\rm{{_{2}^{2+}}}$): a Dimer Perspective and Outlook
Authors: Görller‐Walrand Christiane , Servaes Kelly
Published: November 2009

The complex formation of uranyl (UO$\rm{ {_{2}^{2+}}}$) with oxalic acid (HOOCCOOH) in acetone is studied by UV/VIS, absorption, luminescence, and excitation spectroscopy. Based on solid‐state crystallographic data, we propose a dimer structure with D2h symmetry for the complex in solution. This symmetry is vibrationally distorted to D2 by the out‐of‐plane equatorial‐ligand vibration. From the spectroscopic point of view, this vibration induces intensity in the transitions Πg←Σ$\rm{{_{g}^{+}}}$ and one component of Δg←Σ$\rm{ {_{g}^{+}}}$. From the photochemical point of view, this vibration induces a twisting mechanism that destroys the complex. From the theoretical point of view, it is worthwhile to notice that the symmetry of the odd out‐of‐plane vibration is the same as the symmetry of the odd LUMO (fxyz). By vibrating accordingly to the LUMO symmetry, the complex is self‐destroying by absorption of light, and the uranyl is regenerated. A small comment is devoted to a possible δ–δ interaction and the quintuple U2 bond distance proposed by Gagliardi and Ross [29].
NMR Characterization of Lanthanide(3+) Complexes of Tetraazatetrakisphosphinato and Tetraazatetra­kisphosphonato Ligands
Authors: Pereira Giovannia A. , Ball Laura , Sherry A. Dean , Peters Joop A. , Geraldes Carlos F. G. C.
Published: November 2009

The three‐dimensional structures in aqueous solution of the entire series of the Ln3+ complexes [Ln(DOTP*‐Et)]− (formed from the free ligand P,P′,P″,P′′′‐[1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetrayltetrakis(methylene)]tetrakis[P‐ethylphosphinic acid] (H4DOTP*‐Et) were studied by NMR techniques to rationalize the parameters governing the relaxivity of the Gd3+ complex and evaluate its potential as MRI contrast agent. From the 1H‐ and 31P‐NMR lanthanide‐induced‐shift (LIS) values, especially of the [Yb(DOTP*‐Et)]− complex, it was concluded that the [Ln(DOTP*‐Et)]− complexes adopt in solution twisted square antiprismatic coordination geometries which change gradually their coordination‐cage structure along the lanthanide series. These complexes have no inner‐sphere‐H2O coordination, and preferentially have the (R,R,R,R) configuration of the P‐atoms in the pendant arms. Self‐association was observed in aqueous solution for the tetraazatetrakisphosphonic acid ester complexes [Ln(DOTP*‐OEt)]− (=[Ln(DOTP‐Et)]−) and [Ln(DOTP*‐OBu)]− (=[Ln(DOTP‐Bu)]−) at and above 5 mM concentration, through analysis of 31P‐NMR, EPR, vapor‐pressure‐osmometry, and luminescence‐spectroscopic data. The presence of the cationic detergent cetylpyridinium chloride (CPC; but not of neutral surfactants) shifts the isomer equilibrium of [Eu(DOTP*‐OBu)]− to the (S,S,S,S) form which selectively binds to the cationic micelle surface.
A [Cyclentetrakis(methylene)]tetrakis[2‐hydroxybenzamide] Ligand That Complexes and Sensitizes Lanthanide(III) Ions
Authors: D'Aléo Anthony , Xu Jide , Do King , Muller Gilles , Raymond Kenneth N.
Published: November 2009

The synthesis of the cyclen derivative H4L1⋅2 HBr containing four 2‐hydroxybenzamide groups is described. The spectroscopic properties of the LnIII conplexes of L1 (Ln=Gd, Tb, Yb, and Eu) reveal changes of the UV/VIS‐absorption, circular‐dichroism‐absorption, luminescence, and circularly polarized luminescence spectra. It is shown that at least two metal‐complex species are present in solution, whose relative amounts are pH dependent. At pH>8.0, an intense long‐lived emission is observed (for [TbL1] and [YbL1]), while at pH<8.0, a weaker, shorter‐lived species predominates. Unconventional LnIII emitters (Pr, Nd, Sm, Dy, and Tm) were sensitized in basic solution, both in the VIS and in the near‐IR, to measure the emission of these ions.
Solution Chemistry of Europium(III) Aqua Ion at Micromolar Concentrations as Probed by Direct Excitation Luminescence Spectroscopy
Authors: Andolina Christopher M. , Mathews Ryan A. , Morrow Janet R.
Published: November 2009

Direct excitation europium(III) luminescence spectroscopy is used to study the speciation of aqueous europium(III) ions at micromolar concentrations and near neutral pH. The pH and concentration dependence of the europium(III) 7F0→5D0 excitation peak is consistent with the formation of both mononuclear and dinuclear europium(III) hydroxide complexes at pH 6.5. Luminescence intensity and lifetime quenching studies in the presence of NdIII at pH 5.0 and 6.5 support the formation of a dinuclear complex at pH 6.5. Steady state excitation and time‐resolved luminescence spectroscopy are consistent with the formation of innersphere nitrate and fluoride complexes, but outersphere perchlorate and chloride complexes at pH 6.5 and 5.0.
The Heterometallic Clusters of Trivalent Rare Earth Metals of [Ln(OPh)6{Li(dme)}3], with Ln=Eu and Sm
Authors: Maudez William , Fromm Katharina M.
Published: November 2009

Two new heterobimetallic phenoxide LnIII–Li complexes of formula [Ln(μ2‐OPh)6{Li(dme)}3] (Ln=Sm, Eu) have been synthesized and characterized using single‐crystal X‐ray diffraction. These two compounds are isostructural.
Lanthanide(III) Complexes of 2‐[4,7,10‐Tris(phosphonomethyl)‐1,4,7,10‐tetraazacyclododecan‐1‐yl]acetic Acid (H7DOA3P): Multinuclear‐NMR and Kinetic Studies
Authors: Campello Maria Paula , Balbina Marina , Santos Isabel , Lubal Přemysl , Ševčík Radek , Ševčíková Romana
Published: November 2009

The protonation constants of 2‐[4,7,10‐tris(phosphonomethyl)‐1,4,7,10‐tetraazacyclododecan‐1‐yl]acetic acid (H7DOA3P) and of the complexes [Ln(DOA3P)]4− (Ln=Ce, Pr, Sm, Eu, and Yb) have been determined by multinuclear NMR spectroscopy in the range pD 2–13.8, without control of ionic strength. Seven out of eleven protonation steps were detected (pK$\rm{{_{i}^{H}}}$=13.66, 12.11, 7.19, 6.15, 5.77, 2.99, and 1.99), and the values found compare well with the ones recently determined by potentiometry for H7DOA3P, and for other related ligands. The overall basicity of H7DOA3P is higher than that of H4DOTA and trans‐H6DO2A2P but lower than that of H8DOTP. Based on multinuclear‐NMR spectroscopy, the protonation sequence for H7DOA3P was also tentatively assigned. Three protonation constants (pKMHL, pKMH2L, and pKMH3L) were determined for the lanthanide complexes, and the values found are relatively high, although lower than the protonation constants of the related ligand (pK$\rm{{_{3}^{H}}}$, pK$\rm{{_{4}^{H}}}$, and pK$\rm{{_{5}^{H}}}$), indicating that the coordinated phosphonate groups in these complexes are protonated. The acid‐assisted dissociation of [Ln(DOA3P)]4− (Ln=Ce, Eu), in the region cH+=0.05–3.00 mol dm−3 and at different temperatures (25–60°), indicated that they have slightly the same kinetic inertness, being the [Eu(H2O)9]3+ aqua ion the final product for europium. The rates of complex formation for [Ln(DOA3P)]4− (Ln=Ce, Eu) were studied by UV/VIS spectroscopy in the pH range 5.6–6.8. The reaction intermediate [Eu(DOA3P)]* as ‘out‐of‐cage’ complex contains four H2O molecules, while the final product, [Eu(DOA3P)]4−, does not contain any H2O molecule, as proved by steady‐state/time‐resolved luminescence spectroscopy.
Self‐Assembly of Spheroidal Structures: The Coordination Chemistry of Pentacyanocyclopentadienide
Authors: da Silva Carlos , Bergamo Mirka , Černý Radovan , Williams Alan F.
Published: November 2009

Modelling studies show that the anion pentacyanocyclopentadienide, 1, can complex linearly coordinating cations such as silver(I) and copper(I) to form a spheroidal complex [M30(1)12]18+ with minimum distortion. The anion 1 complexes transition metal ions to give species which appear to be polymers in the solid state. The structure of Ag(1) was determined by powder diffraction and shows a one‐dimensional polymeric structure with three coordinate AgI and two CN functions of the ligand 1 non‐coordinated. No evidence for the formation of the spheroidal complex was found.