The Open Physical Chemistry Journal最新文献

{"title":"Charge-Transfer Patterns for [Ru(NH3)6]3+/2+ at SAM Modified Gold Electrodes: Impact of the Permeability of a Redox Probe","authors":"T. Dolidze, S. Rondinini, A. Vertova, M. Longhi, D. Khoshtariya","doi":"10.2174/1874067700802010017","DOIUrl":"https://doi.org/10.2174/1874067700802010017","url":null,"abstract":"Electrochemical performance of a (Ru(NH3)6) 3+/2+ redox couple at gold electrodes modified by alkanethiol self assembled monolayer (SAM) films of the type (-SH -(CH2)n - CH3) with different number of methylene units (n = 2 to 10) in the presence and absence of glucose additives has been studied using fast scan cyclic and steady-state voltammetry. Specific scatter of measured rate constants caused by enhanced sensitivity of this probe to minor defects of SAMs has been observed in a general agreement with the published data for thicker SAMs (n = 9 to 18). In addition, we have disclo- sed the anomalous viscosity-imposed drop of the heterogeneous rate constant for the case of Au electrodes modified by thinner n-alkanethiol SAMs (n = 2, 4). Taking into the account the fact of (Ru(NH3)6) 3+/2+ couple's capability to penetrate into the SAM interior, we ascribe the obtained results to the manifestation of the solvent-friction mechanism under the condition where the redox species presumably together with a few of solvating water molecules reside in a SAM's peri- pheral interior marked by much higher local viscosity (slower dielectric relaxation) compared to the electrolyte solution.","PeriodicalId":250297,"journal":{"name":"The Open Physical Chemistry Journal","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115030894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Raman Spectroscopic Studies of Polyfluorenes","authors":"S. Guha","doi":"10.2174/1874067700802010006","DOIUrl":"https://doi.org/10.2174/1874067700802010006","url":null,"abstract":"Polyfluorenes reveal a complex interplay between emissive properties and intra- and intermolecular structure. Vibrational frequencies and intensities determined by Raman spectroscopy are strongly influenced by variations in the backbone as well as side chain conformations. Changes in the structural and electronic properties of two side group substi- tuted polyfluorenes (PF): ethyl-hexyl substituted PF (PF2/6) and dioctyl substituted PF (PF8) as a function of solvent, thermal cycling, and hydrostatic pressure via Raman scattering are presented. The vibrational frequencies and intensities of fluorene oligomers with various alkyl side chain conformations are calculated using hybrid density-functional theory. A comparison of the computed vibrational spectra of single chain fluorene oligomers with our experimental data shows that the conformational isomers in PF8 are a direct consequence of the side chain conformation.","PeriodicalId":250297,"journal":{"name":"The Open Physical Chemistry Journal","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128712583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Genetic Code via Gödel Encoding","authors":"T. Négadi","doi":"10.2174/1874067700802010001","DOIUrl":"https://doi.org/10.2174/1874067700802010001","url":null,"abstract":"The genetic code structure into distinct multiplet-classes as well as the numeric degeneracies of the latter are revealed by a two-step process. First, an empirical inventory of the degeneracies (of the shuffled multiplets) in two speci- fic equal moieties of the experimental genetic code table is made and transcribed in the form of a sequence of integers. Second, a Godel Encoding procedure is applied to the latter sequence delivering, as an output, a Godel Number the digits of which, from the decimal representation, could remarkably describe the amino acids and the stops and allow us also to compute the exact degeneracies, class by class. The standard and the vertebrate mitochondrial genetic codes are conside- red and their multiplet structure is fully established.","PeriodicalId":250297,"journal":{"name":"The Open Physical Chemistry Journal","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128116931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dynamics in Ultrathin Films: Particle Tracking Microrheology of Langmuir Monolayers","authors":"L. J. Bonales, Hernán Ritacco, J. E. F. Rubio, R. Rubio, F. Monroy, F. Ortega","doi":"10.2174/1874067700701010025","DOIUrl":"https://doi.org/10.2174/1874067700701010025","url":null,"abstract":"Particle tracking has been shown to be a powerful technique for measuring bulk and interfacial rheology of flu- ids. The Brownian motion of microparticles trapped at interfaces is very sensitive to the viscosity of the subphase, and to the contact angle of the particles. The Stokes-Einstein relation is fulfilled if the friction factor is properly taken into ac- count. The diffusion coefficient of the latex microparticles spread on surfactant monolayers allows one to calculate the shear viscosity of the monolayer using Danov's theory. Good agreement was found with previous results for monolayers of pentadecanoic acid. The method has also been used to study monolayers of n-dodecanol. Moreover, the shear viscosity of a polymer monolayer has been calculated by particle tracking, and the results show good agreement with data obtained by canal viscosimetry. The temperature dependence of the shear viscosity shows the existence of a glass transition for monolayers of poly(4-hydroxystyrene).","PeriodicalId":250297,"journal":{"name":"The Open Physical Chemistry Journal","volume":"67 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124894651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Crystallization Behavior of Acetaminophen in Nanopores","authors":"G. T. Rengarajan, D. Enke, M. Beiner","doi":"10.2174/1874067700701010018","DOIUrl":"https://doi.org/10.2174/1874067700701010018","url":null,"abstract":"The influence of nanoconfinement on the crystallization behavior of acetaminophen, a polymorphic drug occur- ring in three different crystalline forms, is investigated. Differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS) data for a series of controlled porous glasses (CPGs) filled with acetaminophen are presented. The re- sults show clearly that (i) the usually inaccessible crystalline form III of acetaminophen can be produced in pores with di- ameters between 22 and 103 nm and that (ii) the life time of amorphous acetaminophen is significantly increased in 10 nm pores. Bulk melting temperature and heat of melting of form III are estimated based on the Gibbs-Thomson equation. The experimental findings are confronted with the predictions of theoretical approaches aimed to describe thermodynamics and crystallization kinetics in nano-sized systems in order to understand the physical background of the observed changes.","PeriodicalId":250297,"journal":{"name":"The Open Physical Chemistry Journal","volume":"24 8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128791070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Alternative Masks for Nanolithography","authors":"D. Ingert","doi":"10.2174/1874067700701010010","DOIUrl":"https://doi.org/10.2174/1874067700701010010","url":null,"abstract":"The use of masks coming from research field as different as colloids, polymers or nanomaterials is a recently emerging field. Recent advances in this area have developed a variety of practical routes which have a great potential to overcome or at least complete the high-cost lithographic techniques. This review focuses on three techniques that try to reduce to the nanometer range, the size of the mask. The major difference between these procedures is related to the type of mask used. The first technique is called colloidal lithography, the mask is a monodispersed-beads template. The second is the block copolymer lithography and the third technique is the nanocrystal lithography, the mask used is a nano-object. For these three parts, the synthetic routes, the improvements and the applications as well as the limitations will be pre- sented. I. INTRODUCTION Nanotechnology research is led by the demand for ever smaller device features that are required to improve perform- ance and decrease costs in microelectronics, communication and data storage. Lithographic methods are in the centre of this nanotechnology. Rapid replication of features below 50nm is currently a significantly unsolved problem. Generat- ing patterned surfaces at the nanoscale is beyond the limits of standard photolithography techniques. The wavelengths of photons limit the minimum feature sizes in the sub-100nm scale. Thus it appears that whatever technologies are used for fabrication in this region it does not represent simple engi- neering extensions of conventional photolithography. There exists an opportunity to introduce news ideas in replication of meso and nanostructures. Indeed, very few methods pro- vide the ability to work in the sub-50-nm scale (1-3). The well-established methods for the fabrication of nanometer- scale structures (2), such as scanning probe, electron and ion beam lithography provide resolution and integration density required for the industrials demands but the level of throughput rate is far below the requirement. There is a need for alternative simple techniques in order to save processing time and costs (4,5). This need has given rise to different kinds of approaches like, for example, nanoimprint lithogra- phy and soft lithography with the use of self-assembly monolayers (SAMs) (3,6,7). However, for both the mold fabrication problems remain unsolved. In this review we will focus on three techniques that try to reduce to the nanometer range, the size of the mask keep- ing a large surface coverage. The major difference between these procedures is related to the type of mask used while the standard techniques to pattern the substrate like metal depo- sition or ion-plasma etching are kept similar. The main re- quirements present in an efficient method for replication are flexibility in the engraved substrate, fidelity in the replica- tion, low density of defects and large patterned surface. Be- cause all of these characteristics are never present in a sin","PeriodicalId":250297,"journal":{"name":"The Open Physical Chemistry Journal","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124405000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A New Intrinsic Magnetic Property Due to the Mesoscopic Ordering of Cobalt Nanocrystals in Supra-Crystals","authors":"D. Parker, C. Salzemann, I. Lisiecki","doi":"10.2174/1874067700701010005","DOIUrl":"https://doi.org/10.2174/1874067700701010005","url":null,"abstract":"Recently, it has been shown that nanoparticles with a narrow size distribution can self-organize into highly or- dered fcc supra-crystals. This new generation of materials have been found to exhibit unique collective properties, which arise from the periodic ordering of the nanoparticles. Using the expertise we have to control the ordering of cobalt nanoparticles in 3D assemblies, we have been able to carry out a carefully controlled comparative investigation of the magnetic properties of a supracrystal and a disordered assembly. In this letter, we report for the first time a new intrinsic effect of supra-crystal order on the magnetic behavior which we attribute to a decrease in the distribution of energy barri- ers, arising from nanoparticle ordering. We also show that these assemblies can be annealed at 350°C to give a structural transition of the Co nanoparticles from an fcc to hcp phase. This annealing does not induce either coalescence or oxidation of the nanocrystals.","PeriodicalId":250297,"journal":{"name":"The Open Physical Chemistry Journal","volume":"113 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134202679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Highly Dispersed Gold Particles on Polyaniline – A New Nanocatalyst for Selective Hydrogenation","authors":"Florian Klasovsky, M. Steffan, J. Arras, J. Radnik, P. Claus","doi":"10.2174/1874067700701010001","DOIUrl":"https://doi.org/10.2174/1874067700701010001","url":null,"abstract":"A new nanocatalyst which comprises gold particles (average size = (2.5±1.3) nm) supported on intrinsically conductive polyaniline (PANI) was prepared via a sol-method. This Au/PANI catalyst was used for the first time in hydrogenation of the α,β-unsaturated aldehyde citral exhibiting high activity (93% conversion) and selectivity (76%) towards the products of C=O group hydrogenation, geraniol and nerol, whereas the selectivity towards the product of the hydrogenation of the conjugated C=C bond (citronellal) is rather low (23%).","PeriodicalId":250297,"journal":{"name":"The Open Physical Chemistry Journal","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132053236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}