bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a general process for the synthesis of highly substituted imidazoles
Authors: Sisko Joseph , Mellinger Mark 
Published: October 2007

Abstract
Several highly substituted imidazoles have been under investigation at GlaxoSmithKline as potential therapies for the treatment of rheumatoid arthritis and have spawned the need for a general synthetic method for their preparation on a multikilogram scale. We describe herein the optimization of a general method for the preparation of aryl-substituted TosMIC reagents and the ease with which they undergo [3+2] cycloadditions with a host of imines, prepared in situ, to generate densely functionalized imidazoles with various substitution patterns in a completely regioselective manner.
Development of a practical synthesis of sumanirole
Authors: Wuts Peter G. M. , Gu Rui Lin , Northuis Jill M. , Kwan Tricia A. , Beck Doris M. , White Michael J. 
Published: October 2007

Abstract
A new synthesis of sumanirole that is being developed to treat Parkinson's disease is described. The basic skeleton is constructed from 8-hydroxyquinoline and elaborated to the key tricylic intermediate 14. Further elaboration affords a 1,2-amino alcohol, which is converted to an aziridine by a new process. Finally, dissolving metal reduction to open the aziridine and protecting group removal affords sumanirole.
Chemical synthesis project. A new yellow carotenoid
Authors: Giger Alfred 
Published: October 2007

Abstract
Naturally occurring colorants have been used in food processing for centuries to give meals an appealing color. In the first half of the 20th century, the newly discovered brilliant azo dyes, amongst other artificial colorants (indol, triphenylmethane, and methine dyes), were used as pigments for food coloration. The toxicity and/or allergenic potential of some of these colorants were discovered much later. One of these pigments with a critical safety profile is the azo dye tartrazine, which exhibits a nicely fresh greenish-yellow color. The use of tartrazine is now banned in several countries and restricted in others due to its unfavorable safety profile.
With the aim of extending the color fan of nature-identical food colorants offered by Roche and therefore offering a less critical colorant to the food industry, a project was initiated at Roche. The goal was to find a safer, naturally occurring pigment with a color hue similar to tartrazine.
This paper discusses the process of how such a project is addressed in industry, as well as how promising candidates were selected from the wide variety of the naturally occurring carotenoids. The syntheses of some of these carotenoids will also be described.
Photoisomerization by Hula-twist. Photoactive biopigments
Authors: Liu Robert S. H. 
Published: October 2007

Abstract
A review of literature on photoisomerization of bilirubin and photoactive yellow protein suggests possible involvement of the volume-conserving Hula-twist (HT) reaction mechanism in their primary photochemical processes. Additional definitive experiments to verify their involvement are proposed. Information related to photoproducts of bacteriorhodopsin, rhodopsin, and phytochrome are reviewed. For carotenoids, because of participation of the longer lived triplet state in, for example, the photosynthetic apparatus, the involvement of HT is probably less likely.
With the aim of extending the color fan of nature-identical food colorants offered by Roche and therefore offering a less critical colorant to the food industry, a project was initiated at Roche. The goal was to find a safer, naturally occurring pigment with a color hue similar to tartrazine.
This paper discusses the process of how such a project is addressed in industry, as well as how promising candidates were selected from the wide variety of the naturally occurring carotenoids. The syntheses of some of these carotenoids will also be described.
New insights into the role of the macular carotenoids in age-related macular degeneration. Resonance Raman studies
Authors: Bernstein Paul S. 
Published: October 2007

Abstract
The human macula uniquely concentrates extraordinarily high levels of two xanthophyll carotenoids, lutein and zeaxanthin. The function, metabolism, and physiology of these yellow pigments are incompletely understood, but they are likely to prevent age-related damage to the foveal region by virtue of their ability to act as free-radical quenching antioxidants and to absorb phototoxic blue light with high efficiency. A wealth of circumstantial evidence suggests that high macular levels of these two carotenoids may protect against age-related macular degeneration (AMD), but definitive prospective clinical studies still remain to be conducted. It is imperative to gain a greater knowledge of the basic biochemical and physiological mechanisms underlying the specific uptake and metabolism of lutein and zea-xanthin in the macula and to develop improved methods of quantifying macular carotenoid levels noninvasively in order to facilitate the rational design of successful interventions against the leading cause of irreversible blindness in the elderly in the developed world. The development of resonance Raman spectroscopic methods for the objective measurement of macular carotenoid levels in living humans with and without AMD will be reviewed.
Lycopene and prostate cancer risk. Methodological considerations in the epidemiologic literature
Authors: Giovannucci Edward 
Published: October 2007

Abstract
Prostate cancer is the most common cancer in U.S. males. Among potentially beneficial natural compounds is lycopene, which is derived largely from tomato-based products. Recent epidemiologic studies have suggested a potential benefit of this carotenoid against risk of prostate cancer, but not all of the studies have been supportive. The largest prospective dietary study, the Health Professionals Follow-Up Study (HPFS), had found that 2-4 servings of tomato sauce per week were associated with about a 35 % risk reduction of total prostate cancer and a 50 % reduction of advanced prostate cancer in follow-up from 1986 to 1992. Tomato sauce was by far the strongest predictor of plasma lycopene levels in this study. In the largest plasma-based study, high lycopene levels were associated with similar risk reductions for total and advanced prostate cancer. Results from other studies, mostly dietary case-control studies, have been mixed. The reasons for these inconsistencies are unclear. Because lycopene may come from a number of sources, and the bioavailability of lycopene may vary profoundly across these sources, dietary questionnaires are likely to vary markedly in their utility to estimate true variation in body lycopene stores across individuals. With further follow-up in the HPFS, we addressed some possibilities for apparently conflicting results. We confirmed our initial findings with the independent 1992­1998 follow-up period. Our results also indicated various factors may contribute to some of the inconsistencies, including insufficient sample size, low intake of lycopene, failure to account for bioavailability, reliance on a single dietary assessment, and heterogeneity of prostate cancer.
Carotenoids and cervical, breast, ovarian, and colorectal cancer. Epidemiology and clinical trials
Authors: Rock Cheryl L. 
Published: October 2007

Abstract
Recent observational studies and clinical trials that have investigated the relationship between carotenoids (or diets rich in these compounds) and cervical, breast, ovarian, and colorectal cancer have increased knowledge in this area. Although epidemiological studies suggest a protective association, five randomized controlled trials testing the effect of beta-carotene supplementation on regression of cervical dysplasia, a preneoplastic lesion, did not find an effect on rate of regression. In the Women's Healthy Eating and Living (WHEL) Study, the effects of a high-vegetable carotenoid-rich diet on disease-free survival following treatment for breast cancer is being examined in a randomized multicenter diet intervention trial. Few epidemiological studies of dietary factors and risk for ovarian cancer have been conducted, with mixed results. Early case-control and cohort studies of colorectal cancer have generally suggested a protective effect of vegetable consumption, although a recent large cohort study did not confirm this relationship. In two randomized trials, beta-carotene supplementation was not observed to reduce risk of adenoma recurrence. The Polyp Prevention Trial (PPT), which tested the effect of prescribing increased fruit, vegetable, and fiber intake, and reduced dietary fat, revealed no effect of these efforts on adenoma recurrence in the intent to treat analysis. However, serum carotenoid concentrations were associated with decreased risk of recurrence in that study. To move this area of study forward, more research on mechanisms, surrogate biomarkers, and diet­gene interactions is needed.
Nanostructured advanced materials. Perspectives and directions
Authors: Jortner Joshua , Rao C. N. R. 
Published: October 2007

Abstract
A focus of frontline interdisciplinary research today is the development of the conceptual framework and the experimental background of the science of nanostructured materials and the perspectives of its technological applications. We consider some current directions in the preparation, characterization, manipulation, and interrogation of nanomaterials, in conjunction with the modeling of the unique structure­dynamics­function relations of nanostructures and their assemblies. The implications of quantum size and shape effects on the energetics, nuclear­electronic level structure, electric-optical response and dynamics, reveal new unique physical phenomena that qualitatively differ from those of the bulk matter and provide avenues for the control of the function of nanostructures. Current applications in the realm of nanoelectronics, nanooptoelectronics, and information nanoprocessing are addressed, and other directions highlighted. Chemical sciences make a central contribution to this novel and exciting scientific­technological area.
Synthesis of monodispersed model catalysts using softlanding cluster deposition
Authors: Abbet Stéphane , Judai Ken , Klinger Laurent , Heiz Ueli 
Published: October 2007

Abstract
In nanocatalysis, clusters deposited on solid, well-defined surfaces play an important role. For the detection of size effects it is, however, important to prepare samples consisting of deposited clusters of a single size, as their chemical properties change with the exact number of atoms in the cluster. In this paper, the experimental tools are presented to prepare such model systems. The existence of monodispersed clusters is confirmed by various experimental findings. First, the carbonyl formation of deposited Nin clusters shows no change in the nuclearity when comparing the size of the deposited clusters with one of the formed carbonyls. Second, scanning tunneling microscopy (STM) studies show that fragmentation of Sin clusters upon deposition can be excluded. In addition, the adsorption behavior of CO on deposited Pd atoms points to the existence of single atoms on the surface. Furthermore, CO oxidation results on Aun clusters confirm the existence of monodispersed clusters trapped on well-defined adsorption sites. Finally, we use Monte-Carlo simulations to define the range of clusters and defect densities, for which monodispersed clusters can be expected.
Nanophase materials by a novel microwave-hydrothermal process
Authors: Komarneni Sridhar , Katsuki Hiroaki 
Published: October 2007

Abstract
While there are many techniques for the production of nanophase materials, we have been using a hydrothermal process because it is a low-temperature method that can lead to energy savings. A recent innovation is the introduction of microwaves in the hydrothermal system, and we named this process the microwave-hydrothermal (M-H) process. M-H synthesis is a novel processing technology for the production of a variety of nanophase ceramic oxide and metal powders under closed-system conditions. This closed-system technology not only prevents pollution at its source, but also saves energy and, thus, could substantially reduce the cost of producing nanophase powders of all kinds. With several examples, the value of this technique is reviewed here. The M-H technique leads to (a) rapid heating to temperature of treatment, which can save energy and time; (b) increased reaction kinetics by one to two orders of magnitude, which also saves time and energy; (c) formation of novel phases; and (d) selective crystallization.
Morphology of nanostructured materials
Authors: Sanyal M. K. , Datta A. , Hazra S. 
Published: October 2007

Abstract
Here we shall discuss the importance of grazing incidence X-ray scattering techniques in studying morphology of nanostructured materials confined in thin films and multilayers. In these studies, the shapes, sizes, and structures of nanostructured materials and their distribution in composites are investigated. These studies are important for understanding properties that may deviate considerably from the known bulk properties. We shall first outline basics of three X-ray scattering techniques, namely X-ray reflectivity, grazing incidence small-angle X-ray scattering, and grazing incidence diffraction, used for these studies. We shall then demonstrate the utility of these techniques using some known results.
Self-assembled molecular films of tetraamino metal (Co, Cu, Fe) phthalocyanines on gold and silver. Electrochemical and spectroscopic characterization
Authors: Somashekarappa M. P. , Keshavayya J. , Sampath S. 
Published: October 2007

Abstract
The formation of molecular films of 2,9,16,23-tetraamino metal phthalocyanines [TAM(II)Pc; M (II) = Co, Cu, and TAM(III)Pc; M = Fe] by spontaneous adsorption on gold and silver surfaces is described. The properties of these films have been investigated by cyclic voltammetry, impedance, and FT-Raman spectroscopy. The charge associated with Co(II) and Co(I) redox couple in voltammetric data leads to a coverage of (0.35 ± 0.05) x 10-10 mol cm-2, suggesting that the tetraamino cobalt phthalocyanine is adsorbed as a monolayer with an almost complete coverage. The blocking behavior of the films toward oxygen and Fe(CN)6
3-/4- redox couple have been followed by cyclic voltammetry and impedance measurements. This leads to an estimate of the coverage of about 85% in the case of copper and the iron analogs. FT-Raman studies show characteristic bands around 236 cm-1 revealing the interaction between the metal substrate and the nitrogen of the -NH2 group on the phthalocyanine molecules.
Formation of interfacial phases in the epitaxial growth of Sb on Si(111)-7 ¥ 7 reconstructed surface
Authors: Paliwal Vinod Kumar , Vedeshwar A. G. , Shivaprasad S. M. 
Published: October 2007

Abstract
Understanding the evolution of the Sb/Si(111) interface is of great interest in the formation of devices of nanodimensions. We have undertaken in situ (∼10-11 torr) studies of Sb adsorption (at room temperature) and its desorption on the 7 X 7 reconstructed Si(111) surface, by complementary techniques such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and electron energy loss spectroscopy (EELS). For room-temperature (RT) Sb adsorption, the overlayer grows in the Frank van der Merwe mode, forming an interface state of δ(7 X 7) in the submonolayer Sb coverage regime. Adsorption of 1.0 monolayer (ML) Sb at RT shows an abrupt shift of 0.8 eV in the peak position of the Sb 3d5/2 transition owing to band-bending caused by a metallic (7 X 7) to a semiconducting (1 X 1) surface phase transformation. Changes observed in full width at half-maximum (fwhm) and Sb 3d3/2 and 3d5/2 branching ratio are discussed. Thermal annealing experiments provide evidence for agglomeration of Sb islands, before the multilayer and monolayer desorption. During this desorption process, we have observed two novel surface phases of (5 X 5) at 0.4 ML and (5√3 X 5√3­R30°) at 0.2 ML, stable at higher temperatures.
Some properties of spherical and rod-shaped semiconductor and metal nanocrystals
Authors: Landes Christy F. , Link Stephan , Mohamed Mona B. , Nikoobakht Babak , El-Sayed Mostafa A. 
Published: October 2007

Abstract
In this paper, we summarize our results on the effect of changing size and shape of semiconductor and metallic nanocrystals. The change in size (from 3.5 to 1.1 nm) and shape (from spherical to rod) of CdSe nanocrystals is found to affect both their optical and nonradiative properties. In gold quasi-spherical nanocrystals, results on the dependence of the electron-phonon relaxation of the surrounding medium are presented. For gold nanorods, results and conclusions on the mechanism of their self-assembly are presented. Enhanced Raman scattering on their surfaces is studied and compared with that on spherical particle surfaces.
Photoinduced transformations in semiconductor­metal nanocomposite assemblies
Authors: Kamat Prashant V. 
Published: October 2007

Abstract
Semiconductor­metal nanocomposites provide a simple and convenient way to tailor the properties of photocatalysts. Modification of semiconductor surface improves charge separation and promotes interfacial charge-transfer processes in nanocomposite systems. Charge accumulation in the metal layer results in Fermi-level equilibration raising the quasi-Fermi level of the composite close to the conduction band level of the oxide semiconductor. Phototransformations of such compositesincluding morphological changes, interfacial charge-transfer processes and photocurrent generation of TiO2-capped gold colloidsare presented in this review article.
Photochemistry of chromophore-functionalized gold nanoparticles
Authors: Thomas K. George , Ipe Binil Itty , Sudeep P. K. 
Published: October 2007

Abstract
It is generally believed that metal nanoparticles strongly quench the singlet-excited states of chromophores when attached to nanoparticle surfaces, through an energy-transfer mechanism, which limits their application in optoelectronic devices and photonic materials. Recent studies of fluorophore-linked metal nanoparticles reveal that there is a dramatic suppression in the quenching of the singlet-excited state of these molecules and they possess unusual photophysical properties. A summary of our work on the photophysical and excited-state properties of chromophore-functionalized gold nanoparticles is presented in this article. Pyrene-capped gold nanoparticles showed normal fluorescence in nonpolar solvents and an intermolecular excimer formation at higher loadings. The quenching of the emission, observed in pyrene-labeled gold nanoparticles in polar solvents, is attributed to the formation of pyrene radical cation through a photoinduced electron-transfer process. We have also functionalized gold nanoparticles using a thiol derivative of fullerene. The quenching of fluorescence and decreased yields of triplet-excited state, observed in these systems, are attributed to an energy-transfer process.
Functional nanoparticle architectures for sensoric, optoelectronic, and bioelectronic applications
Authors: Willner Itamar , Willner Bilha 
Published: October 2007

Abstract
Tailored sensoric, electronic, photoelectrochemical, and bioelectrocatalytic functions can be designed by organized molecular or biomolecular nanoparticle hybrid configurations on surfaces. Layered receptor-cross-linked Au nanoparticle assemblies on electrodes act as specific sensors of tunable sensitivities. Layered DNA-cross-linked CdS nanoparticles on electrode supports reveal organized assemblies of controlled electronic and photoelectrochemical properties. Au nanoparticle-FAD semisynthetic cofactor units are reconstituted into apo-glucose oxidase (GOx) and assembled onto electrodes. The resulting enzymes reveal effective electrical contacting with the electrodes, and exhibit bioelectrocatalytic functions toward the oxidation of glucose to gluconic acid. Magneto-switchable electrocatalysis and bioelectrocatalysis are accomplished by the surface modification of magnetic particles with redox-relay units. By the attraction of the modified magnetic particles to the electrode support, or their retraction from the electrode, by means of an external magnet, the electrochemical functions of the magnetic particle-tethered relays can be switched between "ON" and "OFF" states, respectively. The magneto-switchable redox functionalities of the modified particles activate electrocatalytic transformations, such as a biocatalytic chemoluminescence cascade that leads to magneto-switchable light emission or the activation of bioelectrocatalytic processes.
Sea-water solubility phase diagram. Application to an extractive process
Authors: Cohen-Adad R. , Balarew Chr. , Tepavitcharova S. , Rabadjieva D. 
Published: October 2007

Abstract
The main goal of this presentation is to tentatively forecast or improve an extractive process. The sea-water system is described using a graphical representation of the quinary ion-pair system Na+, K+, Mg2+/Cl−, SO4
2-//H2O. The operations required by extraction or purification of a sea-water component are simulated by a path through the solubility diagram.The procedure is applied to isothermal evaporation of Black Sea water at 25 °C, and the balance of the crystallization sequence is determined. In the same way, the cooling of residual brine, after precipitation of pure sodium chloride, is studied.
Predicting bioconcentration factors of highly hydrophobic chemicals. Effects of molecular size
Authors: Dimitrov S. D. , Dimitrova N. C. , Walker J. D. , Veith G. D. , Mekenyan O. G. 
Published: October 2007

Abstract
The bioconcentration factor (BCF) is a parameter that describes the ability of chemicals to concentrate in aquatic organisms. Traditionally, it is modeled by the log–log quantitative structure -activity relationship (QSAR) between the BCF and the octanol- water partition coefficient (Kow). A significant scatter in the parabolic log(BCF)/log(K
ow) curve has been observed for narcotics with log(K
ow) greater than 5.5. This study shows that the scatter in the log(BCF)/log(K
ow) relationship for highly hydrophobic chemicals can be explained by the molecular size. The significance of the maximal cross-sectional diameter on bioconcentration was compared with the traditionally accepted effective diameter. A threshold value of about 1.5 nm for this parameter has been found to discriminate chemicals with log(BCF) &gt; 3.3 from those with log(BCF) &lt; 3.3. This critical value for the maximum diameter is comparable with the architecture of the cell membrane. This threshold is half thickness of leaflet constituting the lipid bilayer. The existence of a size threshold governing bioconcentration is an indication of a possible switch in the uptake mechanism from passive diffusion to facilitated diffusion or active transport. The value of the transition point can be used as an additional parameter to hydrophobicity for predicting BCF variation. The effect of molecular size on bioconcentration has been studied by accounting for conformational flexibility of molecules.