Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Chemistry

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 11761 - 11790 of 15551

Full-Text Articles in Entire DC Network

Azocalixarenes.7: Synthesis And Study Of The Absorption Properties Of Novel Mono-Azo Substituted Chromogenic Calix[4]Arenes, Hasaletti̇n Deli̇göz, Özlem Özen Karakuş Jan 2011

Azocalixarenes.7: Synthesis And Study Of The Absorption Properties Of Novel Mono-Azo Substituted Chromogenic Calix[4]Arenes, Hasaletti̇n Deli̇göz, Özlem Özen Karakuş

Turkish Journal of Chemistry

Eight new mono-azo substituted chromogenic calix[4]arenes (1-8) were synthesized by diazo-coupling reactions in which 25,26,27-tribenzoyloxy-28-hydroxy-5,11,17-tri-(tert-butyl)calix[4]arene and diazonium salts (2-, 3-, and 4-nitroaniline; 4-phenyl azoaniline; 3- and 4-chloroaniline; or 2- and 4-methylaniline) formed the corresponding mono-azo substituted derivatives in high yields. The mono-azo substituted calix[4]arenes were characterized by UV-Vis, FT-IR, and ^1H-NMR spectroscopic techniques. Elemental analysis was also carried out. In addition, the effects of varying pH levels and solvents upon the absorption ability of azocalix[4]arenes substituted with electron-donating and electron-withdrawing groups at their o-, m-, and p- positions were studied. The results proved that the absorption maxima of the prepared …


Antimicrobial Activity And Volatile Constituents Of The Flower, Leaf, And Stem Of Paeonia Daurica Grown In Turkey, Gonca Tosun, Nuran Kahri̇man, Canan Albay, Şengül Alpay Karaoğlu, Nuretti̇n Yayli Jan 2011

Antimicrobial Activity And Volatile Constituents Of The Flower, Leaf, And Stem Of Paeonia Daurica Grown In Turkey, Gonca Tosun, Nuran Kahri̇man, Canan Albay, Şengül Alpay Karaoğlu, Nuretti̇n Yayli

Turkish Journal of Chemistry

The volatile constituents of the essential oils from the flower, leaf, and stem of Paeonia daurica Andrews were analyzed by GC and GC-MS. A total of 74 compounds were identified, constituting over 95.0%, 80.8%, and 98.2% of the oil composition of the flower, leaf, and stem of P. daurica, respectively. Aldehydes were shown to be the main group of constituents of the flower and stem parts, at 39.1% and 79.8%, respectively. However, the major group in the leaf oil was found to be oxygenated monoterpenes (43.5%). Salicylaldehyde (20.7% and 79.5%) was the major component of the flower and stem oils …


Determination Of Stability Constants Of 5-(2-Hydroxybenzylidene)-2-Thioxodihydropyrimidine-4,6(1h,5h)-Dione With Copper(Ii) And Mercury(Ii) Ions, Morteza Bahram, Nader Noroozi Pesyan, Abdolhossein Naseri, Masomeh Tasbihforosh Jan 2011

Determination Of Stability Constants Of 5-(2-Hydroxybenzylidene)-2-Thioxodihydropyrimidine-4,6(1h,5h)-Dione With Copper(Ii) And Mercury(Ii) Ions, Morteza Bahram, Nader Noroozi Pesyan, Abdolhossein Naseri, Masomeh Tasbihforosh

Turkish Journal of Chemistry

In this work, a hard model chemometric method was used to determine the stability constants of copper(II) and mercury(II) complexes with the newly synthesized ligand 5-(2-hydroxybenzylidene)- 2-thioxodihydropyrimidine-4,6(1H,5H)-dione in acetonitrile by UV-Vis spectrophotometry. The ligand forms stable complexes with both metal cations. The protonation constants of the ligand were also measured in an ethanol-water (1:1) mixture.


Synthesis And Antimicrobial Activity Of Methoxy Azachalcones And N-Alkyl Substituted Methoxy Azachalconium Bromides, Canan Albay, Nuran Kahri̇man, Nagi̇han Yilmaz İskender, Şengül Alpay Karaoğlu, Nuretti̇n Yayli Jan 2011

Synthesis And Antimicrobial Activity Of Methoxy Azachalcones And N-Alkyl Substituted Methoxy Azachalconium Bromides, Canan Albay, Nuran Kahri̇man, Nagi̇han Yilmaz İskender, Şengül Alpay Karaoğlu, Nuretti̇n Yayli

Turkish Journal of Chemistry

In this study, 18 new N-octyl, N-decyl, and N-dodecyl substituted o-, m-, and p-methoxy (E)-3- and 4-azachalcones, {4- or 3-[(1E)-3-(4-, 3-, or 2-methoxyphenyl)-3-oxoprop-1-en-1-yl]-1-alkyl (C_{8,10,12}) pyridinium bromides} (1a-6a, 1b-1b, and 1c-6c), and 4 new o-, and m-methoxy (E)-3- and 4-azachalcones (2, 3, 5, and 6) were synthesized and tested for antimicrobial activities against Escherichia coli, Yersinia pseudotuberculosis, Enterobacter aerogenes, Pseudomonas aeruginosa, Staphylococcus aureus, Enterococcus faecalis, Bacillus cereus, and Candida albicans. N-Alkyl substituted azachalconium bromides showed good antimicrobial activity against all tested microorganisms with minimal inhibitory concentration (MIC) values in the range of 0.42-58.7 \mu g/mL in most cases. Nonalkylated compounds 1-9 …


Microwave Synthesis Of Some New Antimicrobial And Antiproliferative Butenamides And Pyrrolidine-2,5-Diones, Shadia Mahmoud Abdallah, Halima Aly Hefny Jan 2011

Microwave Synthesis Of Some New Antimicrobial And Antiproliferative Butenamides And Pyrrolidine-2,5-Diones, Shadia Mahmoud Abdallah, Halima Aly Hefny

Turkish Journal of Chemistry

Microwave irradiation, comparable to conventional thermal heating, proves to be a convenient method in assisting the synthesis of some butenamides, pyrrolidine-2,5-diones, and their benzenesulfonamido derivatives, which are known to have biological activities and wide medical and industrial applications. Both procedures were used to compare their efficiency in synthesizing butenamides and pyrrolidine-2,5-diones (2-25), which have important and wide applications, from condensation of \alpha,\beta-unsaturated anhydride (1) with the corresponding amines. Some of the products showed biological or cytotoxic (antiproliferative) activity.


Chemical Composition And Antimicrobial Activity Of The Essential Oils Of Geranium Columbinum L. And G. Lucidum L. (Geraniaceae), Niko Radulovic, Milan Dekic, Zorica Stojanovic-Radic, Radosav Palic Jan 2011

Chemical Composition And Antimicrobial Activity Of The Essential Oils Of Geranium Columbinum L. And G. Lucidum L. (Geraniaceae), Niko Radulovic, Milan Dekic, Zorica Stojanovic-Radic, Radosav Palic

Turkish Journal of Chemistry

The chemistry of Geranium columbinum and G. lucidum volatiles has been studied here for the first time. The essential oils were obtained by hydrodistillation, analyzed by GC and GC-MS, and screened for their in vitro antibacterial and antifungal activity in a microdilution assay. In total, 172 constituents were identified, accounting for 88.1%-96.7% of the detected GC peak areas. The essential oils consisted mainly of fatty acids and fatty acid-derived compounds (65.0%-86.3%). The major compounds of the essential oils were hexadecanoic acid, hexahydrofarnesyl acetone, and tetracosane. The antimicrobial assay showed a strong activity of the oil from aerial parts of G. …


Kinetic Spectrophotometric Determination Of Trace Copper(Ii) Ions By Their Catalytic Effect On The Reduction Of Brilliant Cresyl Blue By Ascorbic Acid, Hali̇l İbrahi̇m Ulusoy, Ramazan Gürkan, Mehmet Akçay Jan 2011

Kinetic Spectrophotometric Determination Of Trace Copper(Ii) Ions By Their Catalytic Effect On The Reduction Of Brilliant Cresyl Blue By Ascorbic Acid, Hali̇l İbrahi̇m Ulusoy, Ramazan Gürkan, Mehmet Akçay

Turkish Journal of Chemistry

In the present study, a novel catalytic-kinetic spectrophotometric method was developed for the determination of trace amounts of copper. It is based on the catalytic effect of Cu(II) on the reduction of brilliant cresyl blue (BCB) by ascorbic acid in pH 5.0 acetate buffer medium. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of BCB at 624 nm. The operating conditions regarding concentration of reagents, pH, time, and temperature were established and optimized in detail. The working curve was linear in the concentration range of 0.1-5.0 \mu g L^{-1}. The maximum percentage error and standard deviation for …


Synthesis Of Novel Tetraoxime Derivative With Hydrazone Side Groups And Its Metal Complexes, İlknur Babahan, Hüseyi̇n Anil, Nursabah Sarikavakli Jan 2011

Synthesis Of Novel Tetraoxime Derivative With Hydrazone Side Groups And Its Metal Complexes, İlknur Babahan, Hüseyi̇n Anil, Nursabah Sarikavakli

Turkish Journal of Chemistry

In this study, the synthesis of a novel tetraoxime (LH_4) derivative containing hydrazone side groups, and its transition metal complexes with Ni(II), Cu(II), Co(II), and Zn(II) ions, were reported. The ligand was synthesized by reacting anti-glyoximehydrazine (GH_2) with terephthaldialdehyde. Polymeric complexes with Ni(II) and Co(II) and binuclear complexes with Cu(II) and Zn(II) of this tetraoxime were isolated. Structural assignments were supported by a combination of ^1H-NMR, ^{13}C-NMR, HMQC, FT-IR, UV-Vis, thermogravimetric analysis (TGA), molar conductances, elemental analyses, and magnetic susceptibility.


A New And Simple Procedure For The Polarographic Speciation And Determination Of Trace Inorganic As(Iii) And As(V) Species, Ülkü Ünal, Güler Somer Jan 2011

A New And Simple Procedure For The Polarographic Speciation And Determination Of Trace Inorganic As(Iii) And As(V) Species, Ülkü Ünal, Güler Somer

Turkish Journal of Chemistry

A new and simple differential pulse polarographic method was developed for the trace determination of As(III) and As(V) species in the same sample. Among several electrolytes, 0.1 M HCl was found to be the most suitable. As(III) had 3 peaks in this medium, and the peak at --0.82 V was chosen because of its peak shape and response to standard additions. In this medium, the limit of detection for As(III) was found to be 1.5 \times 10^{-7} M. Since As(V) is not electroactive, it had to be reduced first into As(III). For this purpose, KI in an acidic and hot …


Chemistry Of 2-Aminothiophene-3-Carboxamide And Related Compounds, Moustafa A. Gouda, Moged A. Berghot, Ghada E. Abd El-Ghani, Khaled M. Elattar, Abd El Galil M. Khalil Jan 2011

Chemistry Of 2-Aminothiophene-3-Carboxamide And Related Compounds, Moustafa A. Gouda, Moged A. Berghot, Ghada E. Abd El-Ghani, Khaled M. Elattar, Abd El Galil M. Khalil

Turkish Journal of Chemistry

This review describes the synthesis and reactions of 2-aminothiophene-3-carboxamides as building blocks for the syntheses of polyfunctionalized heterocyclic compounds.


Facile And Convenient Synthesis Of Pyrimidine, 4h-3,1-Benzoxazin-4-One, Pyrazolo[5,1-B]Quinazoline, Pyrido[1,2-A]Quinazoline, And Chromeno[3' ,4' :4,5]Pyrido[1,2-A]Quinazoline Derivatives, Yousry A. Ammar, Samir Bondock, Abdallah G. El-Sehmi, Mohamed S.A El_Gaby, Ahmed M. Fouda, Hamdy Kh. Thabet Jan 2011

Facile And Convenient Synthesis Of Pyrimidine, 4h-3,1-Benzoxazin-4-One, Pyrazolo[5,1-B]Quinazoline, Pyrido[1,2-A]Quinazoline, And Chromeno[3' ,4' :4,5]Pyrido[1,2-A]Quinazoline Derivatives, Yousry A. Ammar, Samir Bondock, Abdallah G. El-Sehmi, Mohamed S.A El_Gaby, Ahmed M. Fouda, Hamdy Kh. Thabet

Turkish Journal of Chemistry

A convenient synthesis of a series of pyrimidine, 4H-3,1-benzoxazin-4-one, pyrazolo[5,1-b]quinazoline, pyrido[1,2-a]quinazoline, and chromeno[3' ,4' :4,5]pyrido[1,2-a]quinazoline derivatives, via the reactions of versatile and readily accessible methyl 2-(2-cyanoacetamido)benzoate (1) with the appropriate reagents, is described here.


Synthesis And Antimicrobial Activity Of Novel 2-(Pyridin-2-Yl)Thieno[2,3-D]Pyrimidin-4 (3h)-Ones, Nitin G. Haswani, Sanjaykumar B. Bari Jan 2011

Synthesis And Antimicrobial Activity Of Novel 2-(Pyridin-2-Yl)Thieno[2,3-D]Pyrimidin-4 (3h)-Ones, Nitin G. Haswani, Sanjaykumar B. Bari

Turkish Journal of Chemistry

In the present study, some new 2-(pyridin-2-yl)thieno[2,3-d] pyrimidin-4(3H)-ones derivatives (IIa-o) were synthesized. The target compounds (IIa-o) were synthesized through the acid catalyzed condensation of 2-cyano, 3-cyano, and 4-cyano-pyridines with various 2-amino-3-carbethoxythiophenes (Ia-e). All thiophene derivatives were synthesized by Gewald reaction. The structures of the newly synthesized compounds were confirmed by UV-Visible, FT-IR, ^1H-NMR, and mass spectral studies. All synthesized compounds were evaluated for their antimicrobial activity against various gram-positive and gram-negative bacterial and fungal strains. Amongst the synthesized compounds IIa, IIb, IId, IIe, and IIm were found to be active.


Design And Synthesis Of Novel Agrofungicides Based On Naturally Occurring Pbdes, Robert Alexander Smith Jan 2011

Design And Synthesis Of Novel Agrofungicides Based On Naturally Occurring Pbdes, Robert Alexander Smith

Electronic Theses and Dissertations

Cyanobacterial symbionts of Indo Pacific marine sponges, e.g. Dysidea sp., produce hydroxylated (OH-) polybrominated diphenyl ethers (PDBEs) which likely function as chemical deterrents owing to their antifungal and antibacterial properties. Limiting the therapeutic potential and agricultural use of these antimicrobial natural products are the negative connotations associated with non hydroxylated anthropogenic PBDEs. Anthropogenic PBDEs are pervasive global pollutants used as flame retardant additives in many household goods, e.g. furniture, textiles, and electronics. These molecules have a propensity to bioaccumulate in living organisms, they easily traverse the trophic food chains, they are readily passed from mother to offspring, and many of …


Voltammetric Behavior Of Indole-3-Acetic Acid And Kinetin At Pencil-Lead Graphite Electrode And Their Simultaneous Determination In The Presence Of Anionic Surfactant, Yavuz Yardim, Zühre Şentürk Jan 2011

Voltammetric Behavior Of Indole-3-Acetic Acid And Kinetin At Pencil-Lead Graphite Electrode And Their Simultaneous Determination In The Presence Of Anionic Surfactant, Yavuz Yardim, Zühre Şentürk

Turkish Journal of Chemistry

A method was developed for the simultaneous determination of indole-3-acetic acid (IAA) and kinetin, based on the oxidation of both phytohormones at a pencil-lead graphite electrode. The electrochemical behaviors were examined by cyclic, linear sweep, and square-wave voltammetry in the pH range of 2-12. In Britton-Robinson buffer solution (pH 6), the oxidation peaks of IAA and kinetin are well separated by square-wave voltammetry. By adding an anionic surfactant (sodium dodecylsulfate) in a concentration of 50 \mu M, the sensitivity of kinetin was increased significantly without reducing the resolution. The detection limits were 0.14 and 0.11 \mu M (24.53 and 23.67 …


Stable Ester And Amide Conjugates Of Some Nsaids As Analgesic And Antiinflammatory Compounds With Improved Biological Activity, Meci̇t Orhan Uludağ, Burcu Çalişkan Ergün, Duygu Asli Alkan, Ni̇lüfer Ercan, Güler Yağmur Özkan, Erden Banoğlu Jan 2011

Stable Ester And Amide Conjugates Of Some Nsaids As Analgesic And Antiinflammatory Compounds With Improved Biological Activity, Meci̇t Orhan Uludağ, Burcu Çalişkan Ergün, Duygu Asli Alkan, Ni̇lüfer Ercan, Güler Yağmur Özkan, Erden Banoğlu

Turkish Journal of Chemistry

A set of ester and amide derivatives of some acidic NSAIDs, including ibuprofen, ketoprofen, and mefenamic acid (1-3), were synthesized and evaluated for their in vivo analgesic and antiinflammatory activity using the p-benzoquinone-induced writhing test and the carrageenan-induced paw edema model, respectively. Among the synthesized compounds, ester derivatives of ketoprofen showed especially potent analgesic and antiinflammatory activity as compared to the parent drug. In vitro chemical stability studies revealed that ester and amide derivatives were chemically stable in simulated gastric (pH 1.2) and intestinal fluids (pH 6.8). In 80\% human plasma, the ester derivatives were found to be relatively stable …


Mutational Analysis Of Hiv-1 Nucleocapsid Protein And Methods Development For Aptamer Discovery, Wei Ouyang Jan 2011

Mutational Analysis Of Hiv-1 Nucleocapsid Protein And Methods Development For Aptamer Discovery, Wei Ouyang

Chemistry - Dissertations

This dissertation focuses on structural and functional studies related to the interaction between proteins and nucleic acids and their applications. The work reported here includes two projects. The first part of the thesis is on the mutational and combinatorial analysis of HIV-1 nucleocapsid protein (NCp7). Sixteen mutants of NCp7 were constructed and over-expressed in E. coli . The dissociation constants (K d ) between the mutant proteins and the major packaging signal in HIV-1, SL3 RNA, were measured using tryptophan fluorescence titration assay and/or isothermal titration calorimetry (ITC) assay. Most mutants show tolerance of the mutation but some mutants, including …


Accumulation, Speciation, And Distribution Of Metal(Loids) In Plants: Applications Of Synchrotron Techniques In Environmental Sciences, Hiram Castillo-Michel Jan 2011

Accumulation, Speciation, And Distribution Of Metal(Loids) In Plants: Applications Of Synchrotron Techniques In Environmental Sciences, Hiram Castillo-Michel

Open Access Theses & Dissertations

In the last two decades, synchrotron based techniques have gained popularity and been increasingly used in environmental sciences. The present dissertation has relied significantly in the use of synchrotron based techniques to study the speciation, coordination, and distribution of toxic metal(loids) in plants. This study included three plant species: Parkinsonia florida, Prosopis juliflora, and Zea mays. P. florida is a plant species native to the semi-desert regions of North America. The cultivation characteristics of this shrub/tree suggest that it could be used for phytoremediation purposes in semiarid regions. P. florida plants were tested for their capacity to remove arsenic (As) …


I, An Improved Procedure For Alkene Ozonolysis. Ii, Exploring A New Structural Paradigm For Peroxide Antimalarials., Charles Edward Schiaffo Jan 2011

I, An Improved Procedure For Alkene Ozonolysis. Ii, Exploring A New Structural Paradigm For Peroxide Antimalarials., Charles Edward Schiaffo

Department of Chemistry: Dissertations, Theses, and Student Research

The use of ozone for the transformation of alkenes to carbonyls has been well established. The reaction of ozone with alkenes in this fashion generates either a 1,2,4-trioxolane (ozonide) or a hydroperoxyacetal, either of which must undergo a separate reduction step to provide the desired carbonyl compound. There is considerable interest in being able to perform a reductive ozonolysis to directly provide the carbonyl. Previous reports from the Dussault lab have shown that amine N-oxides are able to perform a reductive ozonolysis. In the course of efforts to expand this reaction to other oxyanions it was realized that water was …


Fabrication And Catalytic Property Of Cerium Oxide Nanomaterials, Keren Jiang Jan 2011

Fabrication And Catalytic Property Of Cerium Oxide Nanomaterials, Keren Jiang

Department of Chemistry: Dissertations, Theses, and Student Research

Cerium oxide, or ceria (CeOx: x = 1.5 to 2), has been widely used as a heterogeneous catalyst. Ceria has several properties make it high catalytic active: the fluctuating valence of cerium, the high oxygen storage capacity and high oxygen mobility in the nonstoichiometric ceria. With the high abundance of cerium on earth crust, ceria is a highly effective alternative of the noble metal catalysts. Research has been focused on designing nanostructured ceria and ceria related materials in recent years. The catalytic activity of ceria can be enhanced by the nanoscale effect which can be applied for various …


Characterization Of Composite Broad Band Absorbing Conjugated Polymer Nanoparticles Using Steady-State, Time-Resolve And Single Particle Spectroscopy, Maxwell Scotland Bonner Jan 2011

Characterization Of Composite Broad Band Absorbing Conjugated Polymer Nanoparticles Using Steady-State, Time-Resolve And Single Particle Spectroscopy, Maxwell Scotland Bonner

Electronic Theses and Dissertations

As the global economy searches for reliable, inexpensive and environmentally friendly renewable energy resources, energy conservation by means of photovoltaics has seen near exponential growth in the last decade. Compared to state-of-the-art inorganic solar cells, organic photovoltaics (OPVs) composed of conjugated polymers are particularly interesting because of their processability, flexibility and the potential for large area devices at a reduced fabrication cost. It has been extensively documented that the interchain and intrachain interactions of conjugated polymers complicate the fundamental understanding of the optical and electronic properties in the solid-state (i.e. thin film active layer). These interactions are highly dependent on …


Table Of Contents Jan 2011

Table Of Contents

Journal of the South Carolina Academy of Science

No abstract provided.


President's Message, Justin K. Wyatt Jan 2011

President's Message, Justin K. Wyatt

Journal of the South Carolina Academy of Science

No abstract provided.


Scas Officers And Council Members 2010 - 2011 Jan 2011

Scas Officers And Council Members 2010 - 2011

Journal of the South Carolina Academy of Science

No abstract provided.


Properties And Uses Of Sodium Titanates And Peroxotitanates, David Hobbs Jan 2011

Properties And Uses Of Sodium Titanates And Peroxotitanates, David Hobbs

Journal of the South Carolina Academy of Science

No abstract provided.


Overview Of Hybrid Microwave Technology, Rebecca Schulz, George Wicks, Diane Folz, David Clark Jan 2011

Overview Of Hybrid Microwave Technology, Rebecca Schulz, George Wicks, Diane Folz, David Clark

Journal of the South Carolina Academy of Science

No abstract provided.


Applications Of Biotechnology In Development Of Biomaterials: Nanotechnology And Biofilms, Robin L. Brigmon, Christopher Berry, Raj N. Singh, Roger J. Narayan Jan 2011

Applications Of Biotechnology In Development Of Biomaterials: Nanotechnology And Biofilms, Robin L. Brigmon, Christopher Berry, Raj N. Singh, Roger J. Narayan

Journal of the South Carolina Academy of Science

No abstract provided.


Water Quality And Corrosion: Considerations For Nuclear Reactor Systems, Robert L. Sindelar, Greg T. Chandler, John L. Micalonis Jan 2011

Water Quality And Corrosion: Considerations For Nuclear Reactor Systems, Robert L. Sindelar, Greg T. Chandler, John L. Micalonis

Journal of the South Carolina Academy of Science

No abstract provided.


Nanocarriers For Biomedical Applications, Shuyi Li, Lynsa Nguyen, Hairong Xion, Meiyao Wang, Tom C.-C. Hu, Jin-Xiong She, Steven M. Serkiz, George G. Wicks, William S. Dynan Jan 2011

Nanocarriers For Biomedical Applications, Shuyi Li, Lynsa Nguyen, Hairong Xion, Meiyao Wang, Tom C.-C. Hu, Jin-Xiong She, Steven M. Serkiz, George G. Wicks, William S. Dynan

Journal of the South Carolina Academy of Science

No abstract provided.


Removal And Sequestration Of Iodide From Alkaline Solutions Using Silver-Doped Carbon Nanotubes, Adrian L. Pishko, Steven M. Serkiz, Apparao M. Rao Jan 2011

Removal And Sequestration Of Iodide From Alkaline Solutions Using Silver-Doped Carbon Nanotubes, Adrian L. Pishko, Steven M. Serkiz, Apparao M. Rao

Journal of the South Carolina Academy of Science

No abstract provided.


Table Of Contents Jan 2011

Table Of Contents

Journal of the South Carolina Academy of Science

No abstract provided.