bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cancer-chemopreventive effects of natural sweeteners and related compounds
Authors: Konoshima Takao , Takasaki Midori 
Published: October 2007

Abstract
To search for possible cancer-chemopreventive agents from natural resources, several natural sweeteners were screened by the in vitro assay indicated by the inhibitory effects of Epstein-Barr virus early antigen (EBV-EA) induction. Of active compounds that showed the remarkable inhibitory effects on the EBV-EA induction, stevioside, from the leaves of Stevia rebaudiana, and mogroside V, from the fruits of Momordica grosvenori, exhibited significant inhibitory effects on the two-stage mouse skin carcinogenesis in vivo induced by 7,12-dimethylbenz[a]anthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA). The inhibitory effect of stevioside is stronger than that of glycyrrhizin, which had been known as an antitumor-promoter in chemical carcinogenesis. Furthermore, stevioside also inhibited mouse skin carcinogenesis initiated by peroxynitrite. These results suggest that stevioside and mogroside V might be valuable as chemopreventive agents for chemical carcinogenesis.
Alkaloid synthesis via [3+2] cycloadditions
Authors: Pearson William H. 
Published: October 2007

Abstract
Tin-lithium exchange on (2-azaallyl)stannanes affords nonstabilized 2-azaallyllithiums (2-azaallyl anions) that undergo [π4s+π2s] cycloadditions with alkenes to afford pyrrolidines. The scope of this method has been expanded to include 2-azapentadienyllithiums and heteroatom-substituted 2-azaallyllithiums. Alternatively, the (2-azaallyl)stannanes may also be used to generate nonstabilized azomethine ylides via N-alkylation/destannylation or N-protonation/destannylation, and these ylides were also found to be useful for the synthesis of pyrrolidines by [π4s+π2s] cycloadditions with alkenes. Applications of both methods to the total synthesis of alkaloids such as (+)-coccinine, lepadiformine stereoisomers, lapidilectine B, and indolizidine 239CD have been accomplished.
Recent advances in industrial carotenoid synthesis
Authors: Ernst Hansgeorg 
Published: October 2007

Abstract
Symmetrical C40-carotenoids are efficiently produced by double Wittig olefination of the corrresponding C15-phosphonium salts with C10-dialdehyde. Industrial syntheses of lycopene-, astaxanthin-, and (3R,3'R)-zeaxanthin-C15-phosphonium salts are discussed. An efficient route to a monoprotected C10-dialdehyde for the synthesis of unsymmetrical
C40-carotenoids is presented. Primary polyene allyl alcohols can be converted to the corresponding aldehydes by "TEMPO" oxidation. A high-yield synthesis of meso-zeaxanthin as an example for syntheses of unsymmetrical carotenoids is presented.
Oxidative cleavage of carotenoids catalyzed by enzyme models and beta-carotene 15,15´-monooxygenase
Authors: Woggon Wolf-D. 
Published: October 2007

Abstract
The enzyme that catalyzes the central cleavage of β-carotene is an iron monooxygenase. The protein was isolated from chicken intestinal mucosa and overexpressed in two different cell lines. Inductively coupled plasma (ICP) emission analysis revealed that the hydrophobic 60.3-kDa enzyme contains one iron/mole protein. The substrate specificity was investigated, and the reaction mechanism elucidated incubating α-carotene in the presence of highly enriched 17O2 and H2
18O. A supramolecular enzyme model was synthesized, binding carotenoids Ka > 106 mol-1, which mimics the regiospecific enzymatic cleavage of carotenoids.
Regulation of carotenoid synthesis and accumulation in plants
Authors: Cunningham Francis X. 
Published: October 2007

Abstract
Although genes that encode most enzymes of the carotenoid pathway in higher plants have been identified, the regulatory mechanisms that govern the synthesis and accumulation of carotenoid pigments are still obscure. Recent findings relevant to two aspects of carotenoid pathway control are reviewed: availability of substrate and pathway branching. Experimental approaches that are likely to enhance our understanding of carotenoid pathway regulation are also described.
Lycopene, tomato products, and prostate cancer prevention. Have we established causality?
Authors: Miller Elizabeth C. , Hadley Craig W. , Schwartz Steven J. , Erdman John W. , Boileau Thomas W.-M. , Clinton Steven K. 
Published: October 2007

Abstract
The relationship between tomato products and prostate cancer prevention has been the subject of increasingly intense research activity over the past decade. The hypothesis that tomato products contain phytochemicals, perhaps lycopene and others, that modify prostate carcinogenesis warrants investigation. However, scientists, regulatory agencies, marketers of products, and those defining public health policy have differing opinions regarding the strength of the data when applied to criteria for inference and causality. It is useful to briefly review these criteria and discuss the relative strengths and weaknesses of the published data in order to better define future directions for research. Accepted categories of criteria include: consistency, strength of association, biological gradient, temporality, specificity, biological mechanisms and coherence, and experimental evidence. We believe that continued support for research regarding tomato products, lycopene and other phytochemicals, and prostate cancer risk is warranted and may ultimately serve as the basis for more consistent public health recommendations for the consumer. But, what do we say to the public when the data is still inconclusive? The authors support the recommendation that a minimum of five servings of fruit and vegetables should be consumed daily from a variety of sources. We believe that the hypothesized benefits of tomato products for prostate cancer prevention may be achieved with approximately five servings of tomato products per week. The consumption of lycopene supplements is not currently recommended for prostate cancer prevention or therapy. Future research will allow us to provide more definitive guidelines.
Lycopene in the treatment of prostate cancer
Authors: Kucuk Omer , Sarkar Fazlul H. , Sakr Wael , Khachik Fred , Djuric Zora , Banerjee Mousumi , Pollak Michael N. , Bertram John S. , Wood David P. 
Published: October 2007

Abstract
Dietary intake of lycopene is associated with reduced risk of prostate cancer (PCa). We conducted a clinical trial in men with prostate cancer to investigate the biological and clinical effects of lycopene supplementation. Twenty-six men with prostate cancer were randomly assigned to receive a lycopene supplement or no supplement for three weeks before radical prostatectomy. Subjects in the intervention group (n = 15) were instructed to take a tomato oleoresin extract soft gel capsule (Lyc-O-Mato®, LycoRed Company, Beer Sheva, Israel) containing 15 mg lycopene, 1.5 mg phytoene, 1.5 mg phytofluene, and 5 mg tocopherol twice daily with meals. Prostatectomy specimens were evaluated for pathologic stage, Gleason score, volume of cancer, and extent of high-grade prostatic intraepithelial neoplasia (HGPIN). Biomarkers of cell proliferation and apoptosis were assessed by Western blot analysis in benign and cancerous tissue samples obtained from the prostatectomy specimens. Oxidative stress was assessed by measuring the peripheral blood lymphocyte DNA oxidation product 5-hydroxymethyl-deoxyuridine (5-OH-mdU). Plasma levels of lycopene, insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), and prostate-specific antigen (PSA) were measured at baseline and after three weeks of study period. After the intervention, more men in the intervention group had smaller (<4 cc) tumors, organ-confined disease without involvement of surgical margins or extra-prostatic tissues, and focal involvement of the prostate with HGPIN compared to the control group. Mean plasma PSA levels were lower in the intervention group compared to the control group. This pilot study suggests that a tomato extract containing lycopene and other tomato carotenoids and phytochemicals may have a potential role in the treatment of prostate cancer. Larger clinical trials are necessary to definitively address potential uses of lycopene or tomato extract in the prevention or treatment of prostate cancer.
Role of gene regulation in the anticancer activity of carotenoids
Authors: Sharoni Yoav , Danilenko Michael , Walfisch Shlomo , Amir Hadar , Nahum Amit , Ben-Dor Anat , Hirsch Keren , Khanin Marina , Steiner Michael , Agemy Lilach , Zango Gabriel , Levy Joseph 
Published: October 2007

Abstract
There is extensive evidence that high intake of fruits and vegetables is associated with decreased risk of many types of cancers. Thus, it is widely accepted that diet changes are a powerful means to prevent cancer. Although there is a growing interest in the role of the tomato carotenoid lycopene in cancer prevention and treatment, we hypothesize that a single micronutrient cannot replace the power of the concerted action of multiple agents derived from a diet rich in fruits and vegetables. Indeed, we found that lycopene can synergize with other phytonutrients in the inhibition of cancer cell growth. The mechanism underlying the inhibitory effects of lycopene and other carotenoids involves interference in several pathways related to cancer cell proliferation and includes changes in the expression of many proteins participating in these processes, such as connexins, cyclins, cyclin-dependent kinases, and their inhibitors. These changes in protein expression suggest that the initial effect involves modulation of transcription by ligand-activated nuclear receptors or by other transcription factors. It is feasible to suggest that carotenoids and their oxidized derivatives interact with a network of transcription systems that are activated by different ligands at low affinity and specificity and that this activation leads to the synergistic inhibition of cell growth.
Concepts and applications of the term "dimensionality" in analytical chemistry (IUPAC Technical Report)
Authors: Danzer Klaus , van Staden Jacobus F. , Burns Duncan Thorburn 
Published: October 2007

Abstract
The term "dimensionality" has been used by the analytical chemistry community with several meanings. On different occasions, analysts speak about "two-dimensional" analytical methods, for example, 2D nuclear magnetic resonance spectroscopy, 2D thin-layer chromatography, "two-dimensional" or "three-dimensional" analytical information [1], "two-dimensional" or "three-dimensional" images in surface analytical chemistry, and of "m-dimensional" analytical data [2] obtained, for example, as a result of multicomponent analyses. These examples show that the use of the term "dimensionality" is at times contradictory. This confused position does not promote the unequivocal application of the term "dimensionality" in analytical chemistry. The aim of this document is to provide a concept for the use of the term "dimensionality" as it is related to analytical information.
Sonochemistry as a tool for preparation of porous metal oxides
Authors: Srivastava D. N. , Perkas N. , Zaban A. , Gedanken A. 
Published: October 2007

Abstract
The porous metal oxides are an important class of materials, because the surface area/volume ratio of a material is increased by many fold, making them very useful in surface-related applications. The mesoporous materials were discovered in the 1990s, and since then they have been excellent candidates for materials science research. These mesoporous materials are prepared by hydrolyzing the inorganic precursor (usually metal alkoxide) in an acid, basic, or neutral medium in the presence of an organic structure-directing agent, the surfactant, in a conventional method. Recently, we have demonstrated that the sonochemical technique can be employed for the synthesis of mesoporous metal oxides. The sonochemical method reduced the time period required for such synthesis by many fold, and also produced more stable structures. We got excellent results with silica, titania, yittria-stabilized zirconia (YSZ), and Fe2O3. We also used an inorganic precursor other than an alkoxide for the preparation of mesoporous metal oxides. In this article, we present some of the recent results on this topic.
Structural variations in nanocrystalline nickel films
Authors: Gai Pratibha L. , Mitra Rahul , Weertman Julia R. 
Published: October 2007

Abstract
Nanocrystalline nickel films of technological importance have been grown on various liquid nitrogen-cooled substrates by magnetron sputtering with and without a substrate bias. The atomic structural and chemical studies have unveiled variations in inter- and intragranular structures under the different process conditions. The origin and the development of the crystallization process with and without the substrate bias voltage have been inferred from the results.
Nanotubes of the disulfides of groups 4 and 5 metals
Authors: Nath Manashi , Rao C. N. R. 
Published: October 2007

Abstract
Nanotubes of HfS2, ZrS2, NbS2, and TaS2 have been obtained by the reduction of the corresponding metal trisulfides in a stream of H2 (mixed with an inert gas in some cases) at elevated temperatures. The nanotubes have been characterized by transmission electron microscopy (TEM) and other techniques. These disulfide nanotubes make an important addition to the growing family of nanotubes of inorganic layered materials.
Organometallic precursor route to carbon nanotubes
Authors: Govindaraj A. , Rao C. N. R. 
Published: October 2007

Abstract
Multi-walled as well as single-walled carbon nanotubes are conveniently prepared by the pyrolysis of organometallic precursors, such as metallocenes and phthalocyanines, in a reducing atmosphere. Pyrolysis of organometallics alone or in mixture with hydrocarbons also yields aligned nanotube bundles with useful field emission properties. By pyrolyzing organometallics in the presence of thiophene, Y-junction nanotubes are obtained in large quantities. The junction nanotubes have a good potential in nanoelectronics. Carbon nano-tubes prepared from organometallics are useful for preparing nanowires and nanotubes of materials such as BN, GaN, SiC, and Si3N4.
Mesoscale organization of metal nanocrystals
Authors: Kulkarni G. U. , Thomas P. John , Rao C. N. R. 
Published: October 2007

Abstract
Nanocrystals of metals covered by alkanethiols organize themselves in two-dimensional arrays. We discuss such arrays of metal nanocrystals at length, with focus on the dependence of the structure and the stability of the arrays on the particle diameter and the distance between the particles. Three-dimensional superstructures of metal nanocrystals obtained by the use of alkanedithiols are examined. These ordered two- and three-dimensional structures of thiolized metal nanocrystals are good examples of mesoscale self-assembly. The association of metal nanocrystals to give rise to giant clusters with magic nuclearity provides an even more graphic demonstration of mesoscale self-assembly.
Structure and dynamics of monolayers on planar and cluster surfaces
Authors: Pradeep T. , Sandhyarani N. 
Published: October 2007

Abstract
Organized molecular assemblies have been one of the intensely pursued areas of contemporary chemistry. Among the various methodologies used to make organized monolayer structures, self-assembled monolayers (SAMs) have been attractive to many materials chemists owing to the simplicity of the preparative method and high stability. Advances in various techniques and their application in the study of SAMs have significantly improved our understanding of these molecular systems. These studies have been further intensified since the successful preparation of stable metal clusters protected with monolayers. This article reviews the structure, temperature-induced phase transitions, and associated dynamics of monolayers, principally in the context of our own work in this area. Alkanethiols on Au(111) and Ag(111) are taken as archetypal systems to discuss the properties of 2D SAMs; studies from our laboratory have been on evaporated thin films. Alkanethiols on Au and Ag cluster surfaces are taken as examples of 3D SAMs. Although our principal focus will be on alkanethiols, we will touch upon a few other adsorbate systems as well.
Assembling nanoparticles and biomacromolecules using electrostatic interactions
Authors: Sastry Murali 
Published: October 2007

Abstract
Nanotechnology is witnessing impressive advances on many different fronts. One of the key areas with important commercial implications concerns the assembly of nanoparticles to form thin films and superstructures by what is commonly known as the "bottom-up" approach. This paper covers some of the more recent developments in this fascinating field with particular emphasis on the work from the author's laboratory on assembly of nanoparticles using electrostatic interactions. The use of electrostatic interactions enables extension of the assembly protocols to the immobilization of biomacromolecules such as proteins/enzymes and DNA with exciting application potential.
Nonequilibrium processes for generating silicon nanostructures in single-crystalline silicon
Authors: Sen P. , Akhtar J. 
Published: October 2007

Abstract
The possibility of modifying existing materials through technology has become the recipe for preparation of advanced materials. Nonequilibrium processing of silicon through MeV ion irradiation will be shown here to yield interesting properties. We propose localization of vibrational energy following an ion irradiation process and their transport (nonlinear transport of energy) through linear chains of a single-crystalline lattice. The localization of energy can involve 3­4 atoms, and, hence, nanometer-sized entities evolve, distinguishable from the remaining periodic lattice owing to their unique interatomic distances. The energy required to produce these structures is supplied by a single high-energy heavy ion, incident normal to a suitable crystal face so as to lose energy by the electronic energy loss mechanism. These entities can be trapped at a desired location that leads to silicon nanostructures with modified band-gaps.
Solvothermal routes to capped oxide and chalcogenide nanoparticles
Authors: Gautam Ujjal K. , Ghosh Moumita , Rajamathi Michael , Seshadri Ram 
Published: October 2007

Abstract
We review our recent contributions to the use of solvothermal methods for the preparation of different oxide and chalcogenide nanoparticles. We have prepared sub 10-nm g-Fe2O3, ZnFe2O4, and CoFe2O4 particles by the decomposition of the corresponding cupferron complexes in the presence of n-octylamine or n-dodecylamine in solvothermal toluene. Similarly, dodecanethiol-capped chalcogenide nanoparticles of CdSe have been prepared by reacting cadmium stearates with H2Se under solvothermal conditions. The H2Se is generated in situ by the reduction of Se by tetralin. Using this latter technique, we have also been able to prepare PbSe and PbI2 in toluene under solvothermal conditions, albeit in bulk (rather than nanocrystalline) form. In the preparation of PbI2, HI is prepared by the in situ reduction of I2 by tetralin.
Stars and stripes. Nanoscale misfit dislocation patterns on surfaces
Authors: Pushpa Raghani , Narasimhan Shobhana 
Published: October 2007

Abstract
Close-packed metal surfaces and heteroepitaxial systems frequently display a structure consisting of regularly spaced misfit dislocations, with a network of domain walls separating face-centered cubic (fcc) and hexagonal close-packed (hcp) domains. These structures can serve as templates for growing regularly spaced arrays of nanoislands. We present a theoretical investigation of the factors controlling the size and shape of the domains, using Pt(111) as a model system. Upon varying the chemical potential, the surface structure changes from being unreconstructed to the honeycomb, wavy triangles, "bright stars", or Moiré patterns observed experimentally on Pt(111) and other systems. For the particular case of Pt(111), isotropically contracted star-like patterns are favored over uniaxially contracted stripes.
Mesoscopic domains of cobalt nanocrystals
Authors: Pileni M. P. 
Published: October 2007

Abstract
In this paper, various mesoscopic structures made of cobalt nanocrystals are presented. It is demonstrated that the evaporation time and the application of an external magnetic field during the evaporation process play a major role in the shape of mesostructure obtained. Their magnetic properties change with the shape of the mesostructure.
Electrochemical tuning and mechanical resilience of single-wall carbon nanotubes
Authors: Ghosh Shankar , Teredesai Pallavi V. , Sood A. K. 
Published: October 2007

Abstract
Single-wall carbon nanotubes (SWNTs) are fascinating systems exhibiting many novel physical properties. In this paper, we give a brief review of the structural, electronic, vibrational, and mechanical properties of carbon nanotubes. In situ resonance Raman scattering of SWNTs investigated under electrochemical biasing demonstrates that the intensity of the radial breathing mode varies significantly in a nonmonotonic manner as a function of the cathodic bias voltage, but does not change appreciably under anodic bias. These results can be quantitatively understood in terms of the changes in the energy gaps between the 1D van Hove singularities in the electron density of states, arising possibly due to the alterations in the overlap integral of π bonds between the π-orbitals of the adjacent carbon atoms. In the second part of this paper, we review our high-pressure X-ray diffraction results, which show that the triangular lattice of the carbon nanotube bundles continues to persist up to ∼10 GPa. The lattice is seen to relax just before the phase transformation, which is observed at ∼10 GPa. Further, our results display the reversibility of the 2D lattice symmetry even after compression up to 13 GPa well beyond the 5 GPa value observed recently. These experimental results explicitly validate the predicted remarkable mechanical resilience of the nanotubes.
Substrate temperature dependence of electrical conduction in nanocrystalline CdTe:TiO2 sputtered films
Authors: Sharma S. N. , Shivaprasad S. M. , Kohli Sandeep , Rastogi A. C. 
Published: October 2007

Abstract
TiO2 thin films with high volume fraction (∼50­70 %) of CdTe nanoparticles were prepared by radio frequency (rf) magnetron sputtering from a composite TiO2:CdTe target. With increase in substrate temperature Ts from room temperature (RT ∼300 K) to 373 K, a transition from an ordered structure exhibiting metallic-type conduction to a disordered structure exhibiting nonmetallic-type conduction was observed for annealed nanocrystalline CdTe:TiO2 films. The annealed RT-deposited films showed a large coalescence of distinct islands (size ∼0.3­0.7 µm) mainly of Cd and CdTe, and as result, a 3D network was realized. For metallic regime films, electrical conduction is essentially due to electrical percolation through Cd/CdTe crystallites embedded in an amorphous TiO2 matrix. However, the annealed high Ts films consisted of noncoalescent, small islands (size ∼0.15­0.3 µm) of Cd and CdTe embedded in amorphous TiO2 matrix. Here, the conduction is essentially by hopping mechanism via thermally activated tunneling.